Rozprawy doktorskie: „Synthetic Modification”

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Keenan, Luke. "Post-synthetic modification of metal-organic frameworks". Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619226.

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Post-synthetic modification (PSM) of metal-organic frameworks (MOFs) has increased in importance in the last decade, as a pathway to access more complex surfaces in the pores and channels of porous coordination polymers. This thesis will describe new examples of tandem PSM processes leading to new functionalised MOFs that are inaccessible by direct synthesis. Chapter 1 introduces metal-organic frameworks (MOFs) and reviews the literature ranging from the basic building blocks to 3-D infinite networks. Post-synthetic modification (PSM) is introduced and a review of recent literature given. The aims of this report are also detailed at the close of the chapter. Chapter 2 contains an investigation into the conversion of primary amino to secondary amino groups in the pores of MOFs via a tandem PSM reaction. The pendent amino groups of [Zn4O(BDC-NH2)3] (IRMOF-3) and [Cr3O(OH)(OH2)2(BDC)3] (MIL-101(Cr)-NH2) were modified to produce secondary amino functionalised groups protruding into the void space. Several crystal structures are described including two obtained for the products of the PSM reaction on IRMOF-3. Nitrogen and carbon dioxide absorption was carried and high selectivity for CO2 over N2 was observed. Chapter 3 describes a new hydrothermal synthetic method of MIL-101(Cr)-NH2 and the modification, post-synthesis, to form halo- and azo dye-functionalised pore surfaces by a tandem diazotisation reaction. Quantitative yields are reported for the conversion to the halogenated frameworks inaccessible by direct synthesis with the analogous dicarboxylic acid. Gas adsorption studies demonstrated increased selectivity for CO2 over N2. Chapter 4 details the synthesis of new MOFs, with the potential for PSM, and crystallographic information is supplied for each new extended structure. The linkers, based on isophthalic acid, (1,3-benzenedicarboxylic acid) functionalised at the 5- position, were investigated with a range of metal salts and the resulting frameworks exposed to PSM reaction conditions where appropriate. By using a mixed ligand stoichiometry in the MOF synthesis reaction, 4,4’-bipy and BPDC have been incorporated into new extended frameworks. A new, simpler, synthetic route to the amino functionalised honeycomb framework [Zn4(BDC-NH2)3(NO3)2(H2O)2] (PNMOF-3) is also reported.

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Abdelhameed, Reda Mohamed. "Post-synthetic modification of metal–organic frameworks". Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/15516.

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Doutoramento em Química
Post-synthetic modification (PSM) of metal-organic frameworks encompassing the chemical transformation of the linker present is a promising new route for engineering optical centres and tuning the light emission properties of materials, both in the visible and in the near infrared (NIR) spectral regions. Here, PSM of isoreticular metal-organic framework-3 (IRMOF-3) with ethyl oxalyl monochloride, ethyl acetoacetate, pentane-2,4-dione, 3-(2- hydroxyphenyl)-3-oxopropanal, 2-chloroacetic acid, glyoxylic acid, methyl vinyl ketone and diethyl (ethoxymethylene)malonate followed by chelation of trivalent lanthanide ions afforded intriguing near infrared (Nd3+) and visible (Eu3+, Tb3+) light emitters. IRMOF-3 was used as a case in point due to both its highly porous crystalline structure and the presence of non-coordinating amino groups on the benzenedicarboxylate (bdc) linker amenable to modification. The materials were characterised by elemental analysis, powder X-ray diffraction, optical, scanning and transmission electron microscopy, Fourier transform infrared spectroscopy, and liquid and solid-state nuclear magnetic resonance. The solid-state luminescence properties of Ln-modified-IRMOF-3 were investigated at room temperature. The presence of the bdc aromatic ring, β– diketonate and oxalate enhanced the Ln3+ sensitization via ligand-to-metal energy transfer (anthena effect). As far as photocalysis is concerned, we have synthesized metal−organic frameworks (Cr-MIL-125-AC, Ag-MIL-125-AC) by a green method (solid–vapors reactions). The resulting functionalized materials show a photocatalytic activity for methylene blue degradation up to 6.52 times larger than that of the commercial photocatalyst hombikat UV-100. These findings open the door for further research for improving the photocatalytic performance of metal-organic frameworks.
A modificação pós-síntese de estruturas metalo-orgânicas compreendendo na transformação do ligando orgânico presente é uma nova e promissora via para a engenharia de centros ópticos, permitido sintonizar as propriedades de emissão de luz de materiais na região do visível e do infravermelho próximo. Nesta dissertação, procedeu-se à modificação pós-sintética da estrutura isorreticular metal-orgânica-3 (IRMOF-3) com 2-cloro-2-oxoacetato de etilo, acetoacetato de etilo, pentano-2,4-diona, 3-(2-hidroxifenil)-3-oxopropanal, ácido 2-cloroacético, ácido glioxílico, metilvinil cetona e (etoximetileno)malonato de dietilo, seguida da quelação com iões lantanídeos trivalentes, a qual originou interessantes emissores de luz na região do infravermelho próximo (Nd3+) e do visível (Eu3+, Tb3+). O IRMOF-3 foi usado como um caso de estudo devido quer à sua a estrutura cristalina que apresenta considerável microporosidade, quer à presença de grupos amino livres no ligando benzenodicarboxilato (bdc), que são passíveis de modificação. Os materiais foram caracterizados por análise elementar, difracção de raios X de pós, microscopias óptica, electrónica de varrimento e de transmissão, espetroscopias de infravermelho com transformadas de Fourier e de ressonância magnética nuclear (estados líquido e sólido). As propriedades de luminescência dos materiais Ln-IRMOF-3-modificados foram estudadas à temperatura ambiente. A presença do anel aromático bdc, β- dicetonato e oxalato reforça a sensibilização do Ln3+ através da transferência de energia do ligando para o metal (efeito antena). No que respeita à fotocatálise, sintetizaram-se novos materiais metal-orgânicos (Cr-MIL-125-AC, Ag-MIL-125-AC) através de uma reação sólido-vapor. Estes materiais apresentam uma excelente atividade fotocatalítica para a degradação de azul de metileno até 6,52 vezes maior que o fotocatalisador comercial hombikat UV- 100. Estes resultados abrem a porta a novos estudos que visam melhorar a actividade fotocatalítica de materiais metalo-orgânicos.

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Skrifvars, Mikael. "Synthetic modification and characterisation of unsaturated polyesters". Helsinki : University of Helsinki, 2000. http://ethesis.helsinki.fi/julkaisut/mat/kemia/vk/skrifvars/.

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Argyle, Iain. "Synthetic membrane performance modification by selective species adsorption". Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665413.

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Zhang, Zhenjie. "Template-Directed Synthesis and Post-Synthetic Modification of Porphyrin-Encapsulating Metal-Organic Materials". Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5162.

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Metal-organic materials (MOMs) represent an emerging class of materials comprised of molecular building blocks (MBBs) linked by organic linker ligands. MOMs recently attract great attention because of their ability to exhibit permanent porosity, thereby enabling study of properties in the context of gas storage, gas separation, solid supports for sensors, catalysis and so on. Although MOMs have been studied for over 60 years, the porous nature of MOMs was not systematically and widely explored until the early 1990's. This may be one of the reasons why template-directed synthesis of MOMs remains relatively underexplored, especially when compared to other classes of porous material (e.g. zeolite and mesoporous silicates). However, the study of template-directed synthesis exhibits great significance to the research field of MOMs as these considerations: (i) to access analogues of prototypal MOM platforms that cannot be prepared directly; (2) to create porous materials with new topologies; (3) to transfer the functionality of templates to MOMs; (4) to exert fine control over structural features. In this dissertation, I chose a functional organic material, porphyrin, as templates and succeeded to synthesize a series of porphyrin-encapsulating MOMs, (porph@MOMs), in which the porphyrins were encapsulated inside the cavities as guests. Porphyrins molecules can template the formation cavities with different shapes and sizes (e.g. triangle, square or hexagon) to accommodate the porphyrins molecules when organic ligands with different size and symmetry were utilized during the synthesis. On the other hand, the porphyrins molecules can also template the formation of octahemioctahedral cages or hexahedron cages with porphyrins trapped inside, which further built the tbo, pcu, rtl, zzz, mzz networks. By selecting templated porph@MOMs as platforms, post-synthetic modifications (PSMs) of porph@MOMs were further studied. A cadmium MOM, porph@MOM-10, can undergo PSM by Mn(II) or Cu(II) via single-crystal-to-single-crystal processes. The Mn- and Cu- exchanged PSM variants exhibit catalytic activity for epoxidation of trans-stilbene. Porph@MOM-11 can serve as a platform to undergo a new PSM process involving cooperative addition of metal salts via single-crystal-to-single-crystal processes. The incorporation of the salts leads to higher H2 and CO2 volumetric uptake and higher CO2 vs CH4 selectivity. Porph@MOM-11 was also found to be a versatile platform that can undergo metal ion exchange with Cu2+ in single-crystal-to-single-crystal fashion. The use of mixed metal salt solutions (Cu2+/Cd2+) with varying ratios of metal salts enabled systematic study of the metal exchange process in porph@MOM-11 in such a manner that, at one extreme, only the Cd porphyrin moieties undergo metal ion exchange, whereas at the other extreme both the framework and the porphyrin moiety are fully exchanged. It is also observed that a concerted PSMs approach of metal ion exchange and ligand addition towards a porphyrin-walled MOM, porphMOM-1 affords a porphyrin-encapsulating MOM, porph@MOM-14, in which porphyrin anions are encapsulated in the octahemioctahedral polyhedral cage via weak interactions. Beside of the template-directed synthesis and post-synthetic modification of porph@MOMs, pre-synthetic control of metal-organic materials' structures was also studied in this dissertation. Due to the partial flexibility of 1,3-benzenedicarboxylate linkers, kagom[eacute] lattice and NbO supramolecular isomers were observed from a complexation of bulky 1,3-benzenedicarboxylate ligand to Cu(II) paddlewheel moieties. In addition, a new family of hybrid nanoball vanadium MOM structures (Hyballs) was prepared by the self-assemble of trimesic acid with tetranuclear and pentanuclear vanadium polyoxometalates. These hyballs are robust, permanently porous and their exterior surfaces facilitate cross-linking via hydrogen bonds or coordination bonds to generate pcu networks.

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Amer, Hamzah Harina. "Functionalisation of metal-organic frameworks via post-synthetic modification". Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.723333.

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This thesis is built upon two areas of research concerning metal-organic frameworks (MOFs). The first focuses on the functionalisation of MOFs via post-synthetic modification (PSM). The second involves the investigation on the potential of MOFs as hosts for insect pheromones. Chapter 1 introduces the field of MOF chemistry, and covers their properties along with a brief description of their applications. The concept of PSM is introduced and a review of recent literature given. The aims of the thesis are also detailed at the end of this chapter. Chapter 2 describes the PSM of [Zr6O4(OH)4(BDC-NH2)6], UiO-66-NH2, via Aza-Michael reactions. Different functionalities were successfully introduced into its pores and the degrees of conversion were determined via 1H NMR spectroscopy. Gas sorption measurements (CO2 and N2) of the PSM products were carried out and compared. In particular, two PSM products were shown to exhibit higher CO2 over N2 selectivity than that for the starting MOF, UiO-66-NH2. Chapter 3 describes a new PSM route in obtaining azole-functionalised MOFs via Mannich reactions. The amino groups in three different MOFs were converted into a range of azole-functionalised MOFs with conversions up to 100%. In particular, one of the PSM reactions afforded a new material, formulated as [Zn3(BDC-NH2)1.32(BDC-NHCH2N2C3H3)1.68(C6H12N2)], based on single crystal X-ray crystallography, 1H NMR and TGA analyses. Gas sorption studies demonstrate increased selectivity for CO2 over N2 for the PSM products. One of the modified MOFs was shown to exhibit a high Hg(II) uptake from aqueous solutions. Chapter 4 introduces the concept of using MOFs as hosts for ant pheromones. The factors which influenced the pheromone loading in zinc and zirconium based MOFs were investigated. The MOFs containing the linker BDC-NHPr (2-(propylamino)benzene-1,4-dicarboxylate) were found to be effective at hosting two types of ant pheromones, 3-octanone and (S)-4-methyl-3-heptanone.

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Quader, Sabina, i N/A. "Selective Synthetic Modification of Aminoglycosides for Drug Targeting to Tuberculosis". Griffith University. School of Biomolecular and Physical Sciences, 2007. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20071024.151619.

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The work presented in this thesis details the synthetic modification of the clinically important aminoglycoside antibiotics, neomycin B, paromomycin and tobramycin. We sought to modify aminoglycosides by attaching lipophilic groups, including fatty acids and steroids, with a view to improving the bacterial membrane permeability of these species, and ultimately their efficacy in the treatment of tuberculosis. Our initial synthetic strategy involved direct and specific functionalization of the singular primary hydroxyl group of the aminoglycoside antibiotic neomycin B, with lipophilic groups containing carboxylic acid functions via Mitsunobu esterification. Although, direct and selective Mitsunobu acylation of the primary hydroxyl group proved unsuccessful in the case of the pseudo tetrasaccharide neomycin B, the Mitsunobu reaction did however result in selective chemistry elsewhere in the molecule and this has been exploited for modification of the ido (ring IV) and streptamine (ring II) ring systems. Under carefully controlled conditions, the Mitsunobu reaction has been used for the selective dehydration of the ido ring, to give the talo epoxide, and, under more forcing Mitsunobu dehydration conditions, an aziridine function has been introduced into the streptamine moiety. Both the epoxide and the epoxide-aziridine neomycin building blocks were utilized as synthons in subsequent chemical transformations. Seventeen novel neomycin derivatives featuring modification of ring IV and/or ring II were obtained using this approach. Explicit structural elucidation of all the synthetic intermediates and the final products was achieved using high temperature NMR spectroscopy. Direct and specific functionalization of the singular primary hydroxyl group at the C5 position of the ribose ring (ring III) of neomycin B was achieved, via a procedure based in part on selective tripsylation of the C5III primary hydroxyl group of neomycin B reported previously, followed by subsequent displacement of the tripsyl group by azide. Terminal alkyne containing lipophilic esters were then successfully attached to the ribose residue of neomycin B via Cu(I)-mediated azide-alkyne coupling reaction. In addition to the isolation of two fortuitous, new and versatile synthons i.e. monoanhydro neomycin and bis-anhydro neomycin for modification of ring IV and ring II of neomycin, a third synthon based on neomycin framework, allowing stepwise modification of ring III and ring IV was designed and synthesized. This synthon features an epoxide function in the ido ring, and a protected amine function at the C5 position of the ribose ring. Examples of the stepwise use of this synthon for further synthetic modification of the neomycin framework were demonstrated. Fourteen novel neomycin derivatives featuring modification of ring III and /or ring IV were obtained and characterized. Regioselective Mitsunobu esterification of the single primary hydroxyl group of the pseudo trisaccharide tobramycin was utilized successfully to link a variety of hydrophobic esters with tobramycin. Nine lipophilic tobramycin derivatives with significant structural diversity were synthesised and characterized. In a preliminary study, the applicability of the Mitsunobu dehydration reaction for the regioselective formation of an epoxide ring in the ido moiety of the pseudo tetrasaccharide aminoglycoside antibiotic paromomycin system was confirmed. The regioselective ring-opening of the derived epoxide with azide at C3IV of paromomycin was also successfully demonstrated. In total, forty-two new potential aminoglycoside antibiotics have been synthesized and characterized.

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Washington, Benny Jr. "Enzymatic modification of synthetic mRNA's and their interaction with proteins". DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 1985. http://digitalcommons.auctr.edu/dissertations/1244.

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All eukaryotic mRNAs analyzed to date contain, at their 5' end, a cap structure consisting of a reversed 7-methyl guanosine residue linked at the 5' position of the ribose by a triphosphate to the 5'- position of the terminal residue. Since its discovery, the cap structure has been shown to play an important role in the control of initiation of protein synthesis. Further characterization of mRNAs has revealed other unique properties. Its 3' terminus in most eukaryotes is enriched with a sequence of adenylic acid residues called the poly(A) tail. Photoaffinity binding studies, using photoaffinity capped mRNAs and mRNAs polyadenylated with a photoaffinity label translated in a rabbit reticulocyte lysate system, suggest that proteins or initiation factors are associated with both the 5' and 3' ends. The ability for ribosomes to form complexes in a rabbit reticulocyte lysate system was tested by modi fying mRNAs using 8-azido-[32P]GTP and 8-azido-[32P]ATP. The extent of binding was measured by the total amount of photoaffinity label recovered from a 12% SDS-polyacrylamide gel cut into 1 mm stripes and counted in a LS 7000 scintillation counter. Several proteins labeled both at the 5' and 3' ends with the photoaffinity probe appear to be ribonuclear proteins.

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Quader, Sabina. "Selective Synthetic Modification of Aminoglycosides for Drug Targeting to Tuberculosis". Thesis, Griffith University, 2007. http://hdl.handle.net/10072/367086.

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The work presented in this thesis details the synthetic modification of the clinically important aminoglycoside antibiotics, neomycin B, paromomycin and tobramycin. We sought to modify aminoglycosides by attaching lipophilic groups, including fatty acids and steroids, with a view to improving the bacterial membrane permeability of these species, and ultimately their efficacy in the treatment of tuberculosis. Our initial synthetic strategy involved direct and specific functionalization of the singular primary hydroxyl group of the aminoglycoside antibiotic neomycin B, with lipophilic groups containing carboxylic acid functions via Mitsunobu esterification. Although, direct and selective Mitsunobu acylation of the primary hydroxyl group proved unsuccessful in the case of the pseudo tetrasaccharide neomycin B, the Mitsunobu reaction did however result in selective chemistry elsewhere in the molecule and this has been exploited for modification of the ido (ring IV) and streptamine (ring II) ring systems. Under carefully controlled conditions, the Mitsunobu reaction has been used for the selective dehydration of the ido ring, to give the talo epoxide, and, under more forcing Mitsunobu dehydration conditions, an aziridine function has been introduced into the streptamine moiety. Both the epoxide and the epoxide-aziridine neomycin building blocks were utilized as synthons in subsequent chemical transformations. Seventeen novel neomycin derivatives featuring modification of ring IV and/or ring II were obtained using this approach. Explicit structural elucidation of all the synthetic intermediates and the final products was achieved using high temperature NMR spectroscopy. Direct and specific functionalization of the singular primary hydroxyl group at the C5 position of the ribose ring (ring III) of neomycin B was achieved, via a procedure based in part on selective tripsylation of the C5III primary hydroxyl group of neomycin B reported previously, followed by subsequent displacement of the tripsyl group by azide. Terminal alkyne containing lipophilic esters were then successfully attached to the ribose residue of neomycin B via Cu(I)-mediated azide-alkyne coupling reaction. In addition to the isolation of two fortuitous, new and versatile synthons i.e. monoanhydro neomycin and bis-anhydro neomycin for modification of ring IV and ring II of neomycin, a third synthon based on neomycin framework, allowing stepwise modification of ring III and ring IV was designed and synthesized. This synthon features an epoxide function in the ido ring, and a protected amine function at the C5 position of the ribose ring. Examples of the stepwise use of this synthon for further synthetic modification of the neomycin framework were demonstrated. Fourteen novel neomycin derivatives featuring modification of ring III and /or ring IV were obtained and characterized. Regioselective Mitsunobu esterification of the single primary hydroxyl group of the pseudo trisaccharide tobramycin was utilized successfully to link a variety of hydrophobic esters with tobramycin. Nine lipophilic tobramycin derivatives with significant structural diversity were synthesised and characterized. In a preliminary study, the applicability of the Mitsunobu dehydration reaction for the regioselective formation of an epoxide ring in the ido moiety of the pseudo tetrasaccharide aminoglycoside antibiotic paromomycin system was confirmed. The regioselective ring-opening of the derived epoxide with azide at C3IV of paromomycin was also successfully demonstrated. In total, forty-two new potential aminoglycoside antibiotics have been synthesized and characterized.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Faculty of Science, Environment, Engineering and Technology
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Xu, Heng. "Post-Synthetic Modification of Metal-Organic Frameworks by Solid-Gas Ozonolysis". Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667135.

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Aquesta Tesi doctoral està dedicada a la investigació i l’estudi de l’ozonòlisi en fase solid-gas com un mètode ràpid, simple i versàtil per a la modificació post-sintètica de xarxes metalorgàniques (MOFs). El primer Capítol inclou una breu introducció a l’origen dels MOFs i els conceptes per al disseny i síntesi de materials porosos. Després, fem èmfasi a les actuals metodologies utilitzades en les modificacions post-sintètiques de MOFs il·lustrant els principals avenços i exemples, amb l’objectiu de centrar al lector en el context d’aquesta Tesi. També s’hi expliquen les principals aplicacions de MOFs funcionalitzats post-sintèticament. En el Capítol 2 s’hi exposen els objectius generals i específics d’aquesta Tesi. En el Capítol 3 es desenvolupa la nova metodologia per a realitzar funcionalitzacions post-sintètiques de MOFs basades en l’ozonòlisi sòlid-gas. Els anells ozònids generats s’identifiquen per ressonància magnètica nuclear (RMN). Cal remarcar que aquest nou mètode s’ha demostrat mitjançant transformacions dins d’un mateix cristall, com s’ha confirmat per difracció de raigs X de monocristall conjuntament amb càlculs de teoria del funcional de la densitat (DFT). Finalment, la disposició de la funcionalitat ozònid és demostrada mitjançant un tractament selectiu posterior. En el Capítol 4 s’estén l’ús de l’ozonòlisi sòlid-gas per a la modificació post-sintètica de la porositat de MOFs. Demostrem que, a través de la selecció de MOFs Zr-fcu amb mescla de lligands que consisteixen en parelles on un dels lligands conté enllaços olefina capaços de ser trencats per ozonòlisi i l’altre lligand és resistent a l’ozó, podem realitzar el trencament selectiu dels lligands mitjançant l’ozonòlisi per aconseguir la fusió de microporus en mesoporus en la mateixa estructura del MOF. Així, els MOFs mesoporosos es generen eliminant els fragments de lligand a través de rentats o sublimació, com ho evidencien les seves noves propietats d’adsorció.
This present PhD Thesis has been dedicated to the exploration and study the solid-gas phase ozonolysis as a quick, simple and versatile method for post-synthetic modification of metal-organic frameworks (MOFs). In the first Chapter, a brief introduction to the origin of MOFs is given, followed by typical concepts for design and synthesis of the porous materials. We then pay special attention to the current methodologies that used for post-synthesic modifications of MOFs with state-of-the-art advancements and selected examples, aiming to place the reader in the context of the thesis. Additionally, the main applications of post-synthetically functionalized MOFs are provided. In Chapter 2, the general and specific objectives of the Thesis are introduced. In Chapter 3, we develop a new post-synthetic methodology for functionalization of MOFs based on the solid-gas ozonolysis. The generated ozonide rings are identified by nuclear magnetic resonance (NMR) technique. Moreover, the generality of this method has been proven by a single-crystal-to-single-crystal transformation, as confirmed by single-crystal X-Ray diffraction together with density functional theory (DFT) calculation. Finally, the amenability of ozonide functionality is demonstrated by selectively workup treatment. Chapter 4 extends the use of the solid-gas ozonolysis to post-synthetic modification of MOF porosity. We show that, by carefully selecting mixed-ligand Zr-fcu-MOFs based on organic ligand pairs in which one ligand has ozone-cleavable olefin bonds and the other ligand is ozone-resistant, we were able to selectively break the cleavable ligand via ozonolysis to trigger fusion of micropores into mesopores within MOF framework. Thus, the mesoporous MOFs are subsequently created through removal of ligand fragments by washing or sublimation, as evidenced by their distinct gas sorption properties.

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Albalad, Alcalá Jorge. "Post-Synthetic Modification of Metal-Organic Frameworks (MOFs) and Polyhedra (MOPs)". Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/670090.

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Aquesta Tesi ha estat dedicada al disseny i implementació de noves tècniques de modificació post-sintètica (PSM) aplicades a material metal·loorgànics, principalment polímers de coordinació (CPs), xarxes metal·loorgàniques (MOFs) i políedres metal·loorgànics (MOPs), per tal de modificar les seves propietats fisicoquímiques a nivells inaccessibles a través de metodologies comuns de síntesi directa. La Tesi comença oferint una breu recapitulació bibliogràfica del camp dels materials metal·loorgànics, des dels seus inicis fins a la seva aplicació actual i perspectives de futur. Aquest capítol engloba els conceptes més importants sobre la seva síntesi i modificació post-sintètica, tant en els seus nodes metàl·lics com en els lligands orgànics que construeixen les xarxes; amb un particular èmfasi en les tècniques post-sintètiques desenvolupades fins avui. Seguidament, la tesi és dividida en quatre capítols extra, on cadascun d´ells s´enfoca en un procés de modificació post-sintètica concret. Inicialment, la Tesi es centra en la modificació post-sintètica de les subunitats metàl·liques de polímers de coordinació basats en lligand macrocíclics. La presència d´una font d´ions metàl·lics quelatats dins de la cavitat macrocíclica dels lligands indueix una transició de fase de monocristall a monocristall en contacte amb aigua, obtenint una distribució regular de subunitats; roda de paletes (paddlewheel); bimetàl·liques en la xarxa. Aquesta transició de fase és seguida a través de difracció de monocristall, així com a través de tècniques de caracterització espectroscòpiques i magnètiques. Al següent capítol es postula una tècnica de modificació post-sintètica fins ara inexplorada en el camp dels materials metal·loorgànics. Gràcies a la seva microporositat intrínseca, els MOF poden difondre gasos altament reactius a través de la seva xarxa, el que pot induir potencialment una modificació post-sintètica a través de reaccions sòlid-gas en qüestió de minuts. Per tal de provar aquesta hipòtesi, un MOF decorat amb funcionalitats olefina es va fer reaccionar difonent ozó a través de la seva xarxa. El producte de reacció obtingut presenta clara evidència de tenir dins dels seus canals de reacció l´esperat intermedi de reacció per a la reacció d´ozonòlisi, teòricament inestable. Aquest intermedi pot ser convertit en un pas posterior a grups aldehid o àcid carboxílic de forma quimiselectiva. Tot el procés és caracteritzat per tècniques de ressonància magnètica nuclear (RMN) i difracció de monocristall. Finalment, el coneixement adquirit en la modificació post-sintètica de CPs i MOFs es trasllada al camp dels materials zero-dimensionals. Concretament, aquesta Tesi demostra com políedres metal·loorgànics (MOPs) de rodi poden ser modificats en la seva perifèria a través de química de coordinació i covalent, modificant així les seves propietats fisicoquímiques (solubilitat) sense afectar a la seva integritat estructural. Aquesta modificació post-sintètica obra nous camins cap a l´explotació pràctica d´aquests materials, ja que degut a la seva estructura finita els MOPs poden ser vistos com nanopartícules estequiomètricament funcionalitzades amb solubilitat tuneable. Aquesta modificació post-sintètica permet a més introduït grups funcionals a la perifèria dels MOPs que no poden ser incorporats en síntesi directa. Així, a través d´un procés en dos passos, MOPs amb 24 grups amino o àcid carboxílic són sintetitzats. Ambdós grups presenten objectivament una de les químiques més riques en química covalent o de coordinació, respectivament, el que obra noves fronteres per a l´aplicació d´aquestes nanoplataformes.
Esta Tesis ha sido dedicada al diseño e implementación de nuevas técnicas de modificación post-sintética (PSM) aplicadas a material metalorgánicos, principalmente polímeros de coordinación (CPs), redes metalorgánicas (MOFs) y poliedros metalorgánicos (MOPS) , a fin de modificar sus propiedades fisicoquímicas a niveles inaccesibles a través de metodologías comunes de síntesis directa. La Tesis comienza ofreciendo una breve recapitulación bibliográfica del campo de los materiales metalorgánicos, desde sus inicios hasta su aplicación actual y perspectivas de futuro. Este capítulo engloba los conceptos más importantes sobre su síntesis y modificación post-sintética, tanto en sus nodos metálicos como en los ligandos orgánicos que construyen las redes; con un particular énfasis en las técnicas post-sintéticas desarrolladas hasta la fecha. Seguidamente, la Tesis es dividida en cuatro capítulos extra, donde cada uno de ellos se enfoca en un proceso de modificación post-sintética concreto. Inicialmente, la Tesis se centra en la modificación post-sintética de las subunidades metálicas de polímeros de coordinación basados en ligando macrocíclicos. La presencia de una fuente de iones metálicos quelatados dentro de la cavidad macrocíclicos los ligandos induce una transición de fase de monocristal monocristal en contacto con agua, obteniendo una distribución regular de subunidades; rueda de paletas (paddlewheel) bimetálica en la red. Esta transición de fase es seguida a través de difracción de monocristal, así como a través de técnicas de caracterización espectroscópicas y magnéticas. En el siguiente capítulo se postula una técnica de modificación post-sintética hasta ahora inexplorada en el campo de los materiales metalorgánicos. Gracias a su microporosidad intrínseca, los MOF pueden difundir gases altamente reactivos a través de su red, lo que puede inducir potencialmente una modificación post-sintética a través de reacciones sólido-gas en cuestión de minutos. Para probar esta hipótesis, un MOF decorado con funcionalidades olefina se hizo reaccionar difundiendo ozono a través de su red. El producto de reacción obtenido presenta clara evidencia de tener dentro de sus canales de reacción del esperado intermedio de reacción para la reacción de ozonólisis, teóricamente inestable. Este intermedio puede ser convertido en un paso posterior a grupos aldehído o ácido carboxílico de forma quimiselectiva. Todo el proceso es caracterizado por técnicas de resonancia magnética nuclear (RMN) y difracción de monocristal. Finalmente, el conocimiento adquirido en la modificación post-sintética de CPs y MOFs se traslada al campo de los materiales cero-dimensionales. Concretamente, esta Tesis demuestra cómo poliedros metalorgánicos (MOPS) de rodio pueden ser modificados en su periferia a través de química de coordinación y covalente, modificando así sus propiedades fisicoquímicas (solubilidad) sin afectar a su integridad estructural. Esta modificación post-sintética obra nuevos caminos hacia la explotación práctica de estos materiales, ya que debido a su estructura finita los MOPS pueden ser vistos como nanopartículas estequiométricamente funcionalizadas con solubilidad tuneable. Esta modificación post-sintética permite además introducido grupos funcionales en la periferia de los MOPS que no pueden ser incorporados en síntesis directa. Así, a través de un proceso en dos pasos, MOPS con 24 grupos amino o ácido carboxílico son sintetizados. Ambos grupos presentan objetivamente una de las químicas más ricas en química covalente o de coordinación, respectivamente, lo que abre nuevas fronteras para la aplicación de estas nanoplataformas.
The disserted Ph.D. Thesis was dedicated to the design and implementation of new post-synthetic modification (PSM) techniques to porous metal-organic materials, namely Coordination Polymers (CPs), Metal-Organic Frameworks (MOFs) and Metal-Organic Polyhedra (MOPs), in order to modify their physicochemical properties to inaccessible levels by common direct synthesis methodologies. The Thesis starts offering a brief bibliographic review of the evolution of metal-organic materials field, from their beginnings up to their actual applications and future perspectives. This chapter presents the most relevant concepts in their synthesis and their potential PSM, both in the metallic nodes or in the organic linkers that assemble the framework; with particular emphasis on the post-synthetic methodologies exploited up to date. Next, the Thesis is divided in four extra Chapters, each of them corresponding to a specific post-synthetic modification process. Initially, the Thesis focuses on the post-synthetic modification of the metallic subunits of macrocycle-based CPs. The presence of a second source of metal ions quelated inside the macrocyclic cavity induces a single-crystal-to-single-crystal phase transition in contact with water, obtaining a regular distribution of bimetallic paddlewheel subunits within the framework. Such transition was studied by single-crystal X-Ray diffraction techniques, as well as spectroscopic and magnetic characterization techniques. Next, an unexplored pathway for the PSM of MOFs is postulated. Thanks to their nanoporous structure, MOFs can diffuse highly-reactive gases through their framework in order to modify their structure through solid-gas reactions in a matter of minutes. To this end, an olefin-tagged MOF is post-synthetically modified by diffusing ozone gas through the porous channels of the material. The as-obtained reaction intermediate can be chemoselectively converted to either aldehyde or carboxylic acid groups without affecting the crystalline integrity of the material. The whole two-step process is characterized by Nuclear Magnetic Resonance (NMR) techniques, as well as single-crystal X-Ray diffraction. Afterwards, the post-synthetic modification of metal-organic architectures is extended to zero-dimensional materials. Concretely, it is demonstrated how the surface functionalization of Rhodium (II)-based Metal-Organic Polyhedra, both through coordination or covalent chemistries, is able to tune their solubility within a wide range of solvents, without affecting the scaffold’s integrity. This post-modification opens up new pathways for exploiting these materials. Because of their finite structure, MOPs can be seen as stoichiometrically-functionalized nanoparticles with tunable solubility. Such acquired knowledge is then applied to expand the available roster of Rh(II)-based MOPs. Through a two-step protection/deprotection strategy, two unprecedented Rh-MOPs with 24 free carboxylate or amino groups on their periphery are synthesized, unobtainable by direct synthesis methodologies. Both groups arguably present one of the richest chemistries in coordination and covalent chemistry, respectively, thus opening new pathways and frontiers towards the application of these materials.

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Searle, R. J. "Modification of the mechanical properties of synthetic hydrogels by various techniques". Thesis, London Metropolitan University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254981.

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Azzawi, Itimad Dawood Jumaah. "Application of synthetic jet actuators for modification of separated boundary layers". Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15542/.

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Thompson, Kimberlee Fay. "Modification of polymeric substrates using surface grafted nanoscaffolds". Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-05162005-165302/.

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Thesis (Ph. D.)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2006.
Carter, W. Brent, Committee Member ; Cook, Fred, Committee Member ; Griffin, Anselm, Committee Member ; Michielsen, Stephen, Committee Chair ; Beckham, Haskell, Committee Member ; Bottomley, Lawrence, Committee Member.

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Crawford, Lisa Ann. "Investigating Chemical Modifications in a Complex Proteome". Thesis, Boston College, 2017. http://hdl.handle.net/2345/bc-ir:107651.

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Thesis advisor: Eranthie Weerapana
Thesis advisor: Jianmin Gao
Proteins are composed of the 20 naturally occurring amino acids and are further modified by a variety of post-translational modifications (PTMS). Naturally occurring amino acids are diverse in structure and function. Catalytic amino acids, or nucleophilic amino acids, are of particular interest because of their contribution to chemical transformations in the cell. Synthetic covalent modification is a means to further functionalize or diversify proteins. These modifications, or enhancements, allow for improved understanding of protein structure, function and activity. For instance, isotope labeling of amino acid side chains in NMR studies enable investigators to study protein dynamics upon substrate or ligand binding. Fluorescence labeling is particularly useful to investigate protein cellular localization. Covalent modification is a useful tool to investigate the relative level of activity for protein known to be regulated by PTMs. An important feature of covalent modification reactions is site specificity, as this dictates the location, number of modifications, and protein targets. Tyrosine is of particular interest because it is both nucleophilic and aromatic. These characteristics contribute to the existence of tyrosine residues in both the protein surface and hydrophobic cores. Tyrosine is incorporated into proteins at a relatively low frequency. Unlike lysine, which is ubiquitous on protein surfaces, the low number of potential sites for general tyrosine modifications makes it an attractive site for surface bioconjugation modifications. A low number of surface modifications is less likely to perturb native protein function. Bioconjugation reactions give access to functionalizing the surface of proteins with moieties such as fluorophores, PEG, peptides, or drugs. Tyrosine is an attractive target for modifications because it is found in the active sites of a variety of enzymes such as sialidases, glutathione-S transferases, corticosteroid 11-beta-dehydrogensase, DNA topoisomerase, and ferredoxin-NADP+ reductase. Provided here is a survey of the known non-selective and selective synthetic chemical modification reactions for tyrosine. To investigate nucleophilic amino acids, Activity Based Protein Profiling (ABPP) may be implemented to investigate the role of these residues. ABPP utilizes small molecule covalent probes as a tool to selectively target enzymes in their active state. To investigate a protein of interest (POI) (or class of proteins) by ABPP, it is necessary to use a small molecule covalent probe that selectively reacts with the POI over other proteins within the proteome. Due to this requirement, it is necessary to expand the current ABPP probe toolbox to increase the coverage of what proteins in the proteome may be studied. Inspired by findings in the literature, our lab sought to explore the utility of various aryl halides for implementation in ABPP probes to overcome this limitation. This study revealed dichlorotriazine as a biologically relevant and reactive electrophile. A focus was placed on a dichlorotriazine containing probe library (LAS1-LAS20). LAS17 was discovered to be a potent and selective inhibitor of human glutathione S-transferase pi (GSTP1). Further studies revealed GSTP1 as a novel therapeutic target for the treatment of triple negative breast cancer. Other studies revealed several members of the dichlorotriazine library were found to covalently modify purified recombinant human aldolase A (ALDOA) in the presence of a complex cellular background. Additionally, LAS9 was identified as an inhibitor of ALDOA retro aldol condensation activity in vitro. Lastly, the final chapter highlights two collaborations in which tandem mass spectrometry experiments aid in the characterization of experimental data. In the first collaboration, a quantitative cysteine reactivity profiling method was used to characterize the selectivity of a cysteine reactive covalent NRF2-inducing small molecule, MIND4-17. In the second collaboration, analysis of tryptic mass spectrometry data enabled high resolution characterization of peptide sequencing for superfolder green fluorescent protein (sfGFP) expressed from observed internal nonsense suppression. Identification of the misincorporated amino acid facilitated the elucidation of the cross-talk mechanism
Thesis (PhD) — Boston College, 2017
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry

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Runacres, Selwyn Mark. "The modification of natural occuring polymers for the removal of heavy metal ions". Thesis, Bangor University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340955.

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Matsunaga, Masashi. "Development of physico-chemical pretreatments to enhance the biodegradability of synthetic low-density polyethylene film". Thesis, University of Surrey, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343487.

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Munedzimwe, Tatenda Carol. "The isolation, quantification and synthetic modification of antiplasmodial natural products from sargassum heterophyllum". Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1018252.

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Malaria is one of the most deadly parasitic diseases known to man. Although the number of malaria cases reported each year is decreasing, this disease continues to pose health and economic problems mainly in developing countries. Significant progress has been made in the fight against this disease. This includes the discovery and development of potent antimalarial agents. However, the development of resistance to most of these potent antimalarials has made the development of new antiplasmodial agents of paramount importance. Several promising antiplasmodial agents have been found from the marine environment. Amongst these are the tetraprenylated toluquinols from the brown alga: Sargassum heterophyllum. These metabolites have been reported to exhibit a range of antiplasmodial activity; however, the mechanisms by which these compounds bring about their antiplasmodial activity and the pharmacophoric groups responsible for such activity are unknown. Two species of Sargassum algae were encountered during the course of this project. From the investigation of the geographical and seasonal variation of metabolites of S. heterophyllum and S. elegans we established that there were no significant intra and inter site variations amongst metabolite profiles of both species both within and between the sampled seasons. These results enabled us to establish that the collection of both species from three different sites on the eastern coast of South Africa namely; Kenton on Sea, Port Alfred and Noordhoek in autumn, winter or spring would qualitatively yield the same metabolites. A comparison of metabolite profiles of both species also revealed no qualitative differences between metabolites of S. heterophyllum and S. elegans. The quantities of selected prenylated metabolites extracted from S. heterophyllum using four different extraction techniques was also assessed using qNMR as the method of quantification. This led to the identification of optimal extraction techniques and conditions for the extraction of sargahydroquinoic acid (1.38), sargaquinoic aid (1.39) and sargachromenol (2.10) from S. heterophyllum. From this study, the extraction of algae by soxhlet extraction using EtOH as the extraction solvent led to the extraction of the highest quantities of sargahydroquinoic acid. The potential of other extraction techniques such as microwave assisted extraction, to yield high quantities of the selected metabolites were also identified. With gram quantities of sargahydroquinoic acid (1.38) in hand, this compound was modified by oxidation, reduction, acetylation, methylation and cyclization reactions to yield nine derivatives. The derivatives and four naturally occurring prenylated toluquinols were assessed for antiplasmodial and cytotoxic activity against the FCR-3 Gambian Chloroquine resistant strain of P. falciparum and the MDA-MB-231 breast carcinoma cell line respectively. Comparison of antiplasmodial data for all twelve compounds showed that the hydroquinone moeity of sargahydroquinoic acid (1.38) is important for antiplasmodial activity while esterification of the carboxylic acid group in 1.38 resulted in more potent antiplasmodial compounds. Of all twelve compounds, compound 5.2, the hydroquinone methyl ester of 1.38 was found to be the most potent antiplasmodial compound with an IC₅₀ value of 1.94 μM and a selectivity index of 22.68.

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Das, Lopamudra. "Surface Modification of Synthetic and Natural Polymers using Deep Uv (172 Nm) Irradiation". W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1530192366.

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The ability to modify the surfaces of polymers and impart desirable functionalities without affecting the bulk-mediated physical properties is vital for advanced materials development. Photochemical approaches to surface modification are particularly attractive as they minimize the need for use of hazardous materials used in conventional wet chemical technologies, and are relatively faster, efficient and convenient to use. In this research, we undertook a combined experimental and computational approach to understand the effect of deep UV irradiation on a broad range of polymeric materials, and develop a scalable and deployable surface modification strategy that could be extended to all. Four polyesters, polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate(PBT) and polyethylene napthalate (PEN), Kapton polyimide, a polyolefin and cellulose were the polymers investigated. Technical grades of the material were used in order to understand the fundamental science as well as develop a scalable deployable technology. Surface analysis was done using the X-Ray Photoelectron Spectroscopy (XPS), Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy(ATR-FTIR), Atomic Force Microscopy (AFM) and contact angle measurements. The experiments were carried out using a high intensity 172 nm xenon microplasma lamp, and the effect of varying doses of UV irradiation, 0, 8, 16, and 32 J/cm2 on the polymer surfaces were characterized. The effect of using two different intensity levels was also compared. In case of the polyesters and polyimide, calculated UV/VIS absorption spectra using the ZINDO//B3LYP/321-G method or the AM1/ZINDO approach were used to give an indication of which orbitals were involved in transitions near 172 nm, a valuable tool for predicting future research and development. It was found that 172 nm excimer UV lamp was successful in creating active surface radicals in all the polymers investigated. The AFM results did not indicate any significant surface roughening at 16 J/cm2 total irradiation dose, which was also found to be the radiation level at which a reaction set point was reached in all the polymers. Vapor phase photo-assisted grafting of an alkane and alkene onto to the polyester surfaces indicated a common trend in the surface chemistry changes. to develop a potentially useful low energy surface that would impart anti soil and cleanibility properties, a fluorocarbon was successfully grafted on each material. Water and light mineral oil contact angle measurements confirmed a marked increase in hydrophobicity and oleophobicity, in some cases reaching that close to pure polytetrafluoroethylene. The grafted surface was found to be significantly wash durable. This is a valuable development as the process is minimally hazardous, relatively simple, fast, efficient, economic, and easily scalable and deployable. Particularly in the case of some polymers, such as polyolefins and cellulose, this method bypasses the challenges of complex processing routes and harmful chemicals that are currently used to achieve the same goal.

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Shimko, John C. "Synthetic Tools for the Preparation of Modified Histones". The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1322664987.

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Honohan, Andrew M. "The interaction of synthetic jets with cross flow and the modification of aerodynamic surfaces". Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/20836.

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Lim, Zi-Yian. "Preparation, modification, and characterisation of Yolk-shell structure based catalysts for synthetic gas production". Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/41666/.

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Hydrogen is an emerging energy carrier for oil refining and fuel cell applications. The development of an efficient and stable catalyst to produce hydrogen gas is required for industrial applications. However critical issues in the catalyst that lead to the deactivation of reactions include active metal particle growth and carbon fouling. Industrial catalysts that are frequently overwhelmed by such issues are substituted or re-treated, which is not time and cost efficient. Therefore, developing durable catalysts that are resistant to sintering and carbon fouling remains an area of interest. A novel and anti-agglomeration Ni@yolk-ZrO2 catalyst is first reported in this thesis. A specific study of the ZrO2 hollow shell showed that the varied porosity of the hollow shell contributed to the catalyst’s ability to inhibit the agglomeration of active Ni particles. The steam reforming of methane was selected as the probe study for this catalyst in this research. Before a thorough analysis of the Ni@yolk-ZrO2 catalyst was performed, the systematic synthesis of Ni@SiO2 was studied. The analysis showed that the Ni particle size can be controlled by tuning the synthesis temperature. Water-to-surfactant ratio in the microemulsion was shown to influence the morphology of the Ni@SiO2 particle. The tetraethyl orthosilicate (TEOS) amount added with fractionated dispensing and the amount of NiCl2 were found to have affected the size and morphology of the Ni@SiO2. For the Ni@yolk-ZrO2 sample, the catalyst was characterised by Transmission Electron Microscopy (TEM) and X-Ray Diffraction. TEM was used for morphology analysis, while X-ray Diffraction was performed for phase analysis and crystallite size measurements. Nitrogen adsorption-desorption isotherm was done to measure specific surface area, total pore volume, and the t-plot micropore volume of the samples. Reducibility analysis of the Nickel species of the Ni@yolk-ZrO2 catalyst was carried out using Temperature Programmed Reduction. The anti-agglomeration property of the Ni@yolk-ZrO2 was established from the TEM and X-ray Photoelectron Spectroscopy analysis. Results showed that the active Ni particles were inside the yolk-shell structured framework, which deterred Ni particles from moving onto the surface of the catalyst. Ni particles were found to be stabilised by the abundant volume of pores in the ZrO2 hollow shell. This result indicates that the Ni particles were anchored by the pores and remained stable during the steam reforming of methane. The Ni@yolk-ZrO2 catalyst was tested by varying the volumes of feed (GHSV) and the steam-to-carbon ratio. This catalyst was also subjected to a recyclability test and proved to be better than conventional impregnated Ni/ZrO2 catalysts. The Temperature Programmed Hydrogenation analysis also proofed that the yolk-shell structure framework inhibited higher order of carbon deposits on the Ni@yolk-ZrO2 catalyst. Varying the porosity of the ZrO2 hollow shell was found to affect the performance of the steam reforming of methane. This varied porosity can be achieved by varying the amount of surfactant during the synthesis of Ni@SiO2@ZrO2. X-ray Photoelectron Spectroscopy analysis results showed that the porosity of the ZrO2 hollow shell contributed to the moderately strong hydrothermal stability of the catalyst for the steam reforming of methane. The hollow shell of the ZrO2 was influenced by the instability of the SiO2. TEM analysis of used BrNi-4.8 catalysts showed that the yolk-shell structure framework of the catalyst collapsed. This result suggests that the shell has weak integrity, and proves that the SiO2 was not able to maintain the yolk-shell framework. The results also suggest that the varied porosity of the ZrO2 hollow shell influences the catalysts’ efficiency even though they share the same yolk-shell structure framework. This is likely due to the differences in the pores of each catalyst configuration, which directly affects the Nickel species involved in the catalytic reaction. Finally, it was demonstrated that the Ni@yolk-ZrO2 catalyst exhibits excellent catalytic performance in comparison to conventional catalysts for the steam reforming of methane. Catalytic activity remained stable and achieved a methane conversion of more than 90 % for 150 hours under operating conditions of GHSV of 50400 mL gcat-1h-1 and S/C = 2.5 at 750 oC.

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Issa, Hussein. "Toolbox of post-synthetic mordenite modification strategies : Impact on textural, acidic, and catalytic properties". Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2268.

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Les zéolithes sont des catalyseurs hétérogènes extrêmement utiles et trouvent des applications industrielles répandues. Cependant, leur système microporeux étendu conduit à des facteurs d'efficacité plutôt faibles et favorise le développement de réactions secondaires pouvant réduire considérablement la sélectivité et la stabilité catalytique. La hiérarchisation des zéolithes a été proposée comme stratégie permettant de réduire efficacement la longueur du trajet de diffusion, permettant ainsi d'augmenter le facteur d'efficacité en catalyse. Parmi la multitude de stratégies de hiérarchisation divulguées, l'impact réel des modifications structurelles et chimiques sur les paramètres clés catalytiques est souvent négligé. Le but de cette contribution est donc de faire la lumière sur la qualité effective de la hiérarchisation des zéolites à travers l'étude rationnelle de la dépendance structure / propriété catalytique. Notre étude s'est concentrée sur la mordénite, cette zéolite revêtant une importance particulière en raison de sa forte acidité et de son système de canaux monodimensionnel, ce qui explique pourquoi la mordénite est largement utilisée industriellement dans divers procédés, notamment l'alkylation d'aromatiques, les isomérisations d'alcanes, et les déshydratations d'alcools. Des stratégies de hiérarchisation post-synthétiques sur les mordénites riches et pauvres en aluminium ont été développés sur la base de traitements de basique assisté par CTAB, pyridine à différentes températures (en chauffage conventionnel et par micro-ondes), et par attaque chimique HF en milieu aqueux et organique. Une étude systématique de plus de 50 mordénites post-synthétiquement modifiées a été menée, ce qui nous a permis d'évaluer l'impact de chacune des stratégies de hiérarchisation sur les propriétés texturales, morphologiques, chimiques et catalytiques. Des corrélations majeures entre les caractéristiques structurelles et l'activité catalytique, la sélectivité et la stabilité dans le craquage du n-hexane et dismutation du toluène ont été déduites. Une feuille de route sur la qualité de chaque stratégie de hiérarchisation a ainsi été élaborée
Zeolites are extremely useful heterogeneous catalysts and find widespread industrial applications. Yet, their extended microporous system leads to rather low efficiency factors and favors the development of secondary reactions that can substantially reduce catalytic selectivity and stability. Hierarchization of zeolites has been proposed as strategy for efficiently reducing the diffusion path length, hence allowing to increase the efficiency factor in catalysis. Among the plethora of disclosed hierarchization strategies, the real impact of the structural and chemical modifications on the catalytic key parameters is oftentimes neglected. The aim of this contribution is thus to shed light on the effective quality of zeolite hierarchization through the rational study of structure/catalytic property dependency. Our study focused on mordenite, as this zeolite is of particular importance due to its strong acidity and monodimensional channel system, which explains why mordenite is industrially extensively employed in a variety of processes including alkylations, isomerizations, dehydrations and aminations. A toolbox of post-synthetic hierarchization strategies on aluminium rich and poor mordenites have been developed based on basic treatments assisted by CTAB and pyridine at various temperatures (in conventional and microwave heating) and acid HF etching in aqueous and organic medium. A systematic study of over 50 post-synthetically modified mordenites was conducted, which allowed us to assess the impact of each of the hierarchization strategy on textural, morphological, chemical and catalytic properties. Major correlations between structural features and catalytic activity, selectivity and stability in n-hexane cracking and toluene disproportionation were deduced. A roadmap on the quality of each hierarchization strategy was thus developed

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24

Albrecht, Delphine. "Etude des mutants synthétiques létaux avec l'AICAR chez la levure et conservation chez l'Homme". Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0134/document.

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L’identification d’interactions synthétiques létales (SL) apparait aujourd’hui comme une approche prometteuse, qui permet de cibler directement les cellules cancéreuses. Dans cette étude, nous avons utilisé la levure Saccharomyces cerevisiae en tant qu’organisme modèle simple pour cribler des mutations SL avec une drogue, l’AICAR (5-Amino-4-Imidazole CArboxamide Ribonucleoside). L’AICAR est une molécule connue pour inhiber spécifiquement la prolifération de multiples lignées cancéreuses. Ici, nous montrons que la perte d’ubiquitination de l’histone H2B ou de méthylation de l’histone H3K4 est SL avec l’AICAR. Nos résultats pointent sur l’AICAR causant une accumulation de cellules en G1 due à ses effets sur la localisation subcellulaire de la cycline Cln3, tandis que la perte d’ubiquitination d’H2B ou de méthylation de H3K4 affectent l’expression des deux autres cyclines deG1, CLN1 et CLN2. Ainsi, l’AICAR et la perte d’ubiquitination de l’histone H2B ou de méthylation del’histone H3K4 affectent les trois cyclines simultanément, conduisant à une condition connue pourêtre SL. De plus, cette interaction chemo-genetique s’est révélée être conservée chez les cellules humaines HCT116. En effet, le knock down de RNF40, ASH2L ou MLL2 conduit à une sensibilité àl’AICAR exacerbée. Or, on sait que MLL2 est muté dans de nombreux cancers, ce qui rend cette interaction SL très intéressante dans le cadre d’une approche thérapeutique
Identifying synthetic lethal interactions has emerged as a promising new therapeutic approach that aims to directly target the cancer cells. Here, we used the yeast Saccharomyces cerevisiae as a simple eukaryotic model to screen for mutations resulting in a synthetic lethality with 5-Amino-4-ImidazoleCArboxamide Ribonucleoside (AICAR) treatment. Indeed, AICAR has been reported to specifically inhibit the proliferation of multiple cancer cell lines. Here, we found that loss of two several histone modifying enzymes, including Bre1 (histone H2B ubiquitination) and Set1 (histone H3 lysine 4methylation), greatly enhanced AICAR inhibitory effects on growth. Our results point to AICAR causing a significant accumulation of G1 cells due to its impact on Cln3 subcellular localization, whilebre1 or set1 deletion impacts on the two other G1 cyclins, by affecting CLN1 and CLN2 expression .As a consequence, AICAR and bre1/set1 deletions jointly affect all three G1 cyclins, leading to a condition that is known to result in synthetic lethality. Most importantly, these chemo-genetic synthetic interactions were conserved in human HCT116 cells. Knock-down of RNF40, ASH2L orKMT2D induced a highly significant increased sensitivity to AICAR. As KMT2D is mutated at high frequency in a variety of cancers, this synthetic lethal interaction has an interesting therapeutic potential

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Chalker, Justin M. "Reaction engineering for protein modification : tools for chemistry and biology". Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:52d92917-5c7f-4223-b554-2e1b4fc0b2ea.

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Chemical modification of proteins is critical for many areas of biochemistry and medicine. Several methods for site-selective protein modification are reported in this Thesis that are useful in accessing both natural and artificial protein architectures. Multiple, complementary methods for the conversion of cysteine to dehydroalanine are described. Dehydroalanine is used as a general precursor to several post-translational modifications and glycosylation, polyprenylation, phosphorylation, and lysine methylation and acetylation are all accessible. These modifications and their mimics were explored on multiple proteins, including histone proteins. Unnatural modifications were also explored. The first examples of olefin metathesis and Suzuki-Miyaura cross-coupling on protein substrates are reported. Allyl sulfides were discovered to be remarkably reactive substrates in olefin metathesis, allowing use of this reaction in water and on proteins. For Suzuki-Miyaura cross-coupling, a new catalyst is described that is fully compatible with proteins. Both olefin metathesis and cross-coupling allow the formation of carbon-carbon bonds on proteins. The prospects of these transformations in chemical biology are discussed. Finally, a novel strategy is reported for the installation of natural, unnatural, and post-translationally modified amino acid residues on proteins. This technology relies on addition of carbon radicals to dehydroalanine. This method of "chemical mutagenesis" is anticipated to complement standard genetic manipulation of protein structure.

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26

Chooi, Kok Phin. "Synthetic phosphorylation of kinases for functional studies in vitro". Thesis, University of Oxford, 2014. https://ora.ox.ac.uk/objects/uuid:2adc517a-2876-4a0b-8ead-e9bf164ebc6f.

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The activity of protein kinases is heavily dependent on the phosphorylation state of the protein. Kinase phosphorylation states have been prepared through biological or enzymatic means for biochemical evaluation, but the use of protein chemical modification as an investigative tool has not been addressed. By chemically reacting a genetically encoded cysteine, phosphocysteine was installed via dehydroalanine as a reactive intermediate. The installed phosphocysteine was intended as a surrogate to the naturally occurring phosphothreonine or phosphoserine of a phosphorylated protein kinase. Two model protein kinases were investigated on: MEK1 and p38α. The development of suitable protein variants and suitable reaction conditions on these two proteins is discussed in turn and in detail, resulting in p38α-pCys180 and MEK1-pCys222. Designed to be mimics of the naturally occurring p38α-pThr180 and MEK1-pSer222, these two chemically modified proteins were studied for their biological function. The core biological studies entailed the determination of enzymatic activity of both modified proteins, and included the necessary controls against their active counterparts. In addition, the studies on p38α-pCys180 also included a more detailed quantification of enzymatic activity, and the behaviour of this modified protein against known inhibitors of p38α was also investigated. Both modified proteins were shown to be enzymatically active and behave similarly to corresponding active species. The adaptation of mass spectrometry methods to handle the majority of project's analytical requirements, from monitoring chemical transformations to following enzyme kinetics was instrumental in making these studies feasible. The details of these technical developments are interwoven into the scientific discussion. Also included in this thesis is an introduction to the mechanism and function of protein kinases, and on the protein chemistry methods employed. The work is concluded with a projection of implications that this protein chemical modification technique has on kinase biomedical research.

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27

Rideau, Fabien. "Clonage et modification du génome de Mycoplasma hominis dans la levure Saccharomyces cerevisiae". Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0227/document.

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Mycoplasma hominis est un pathogène humain opportuniste responsable d’infections génitales et néo-natales. Modifier génétiquement cette bactérie est nécessaire afin de comprendre les mécanismes de virulence et d’infection de ce pathogène. Il n’existe à ce jour aucun outil moléculaire efficace permettant de manipuler le génome de M. hominis, limitant les recherches sur sa pathogénicité et son métabolisme particulier reposant sur l’arginine. De nouvelles technologies rassemblées sous le terme de Biologie de Synthèse (BS) ont récemment émergé, offrant des perspectives inédites pour l’étude des mycoplasmes en permettant de modifier leurs génomes à grande échelle et de produire des souches mutantes. Ces travaux menés au J. Craig Venter Institute (JCVI, USA) ont montré que le génome de mycoplasmes apparentés pouvait être cloné et manipulé dans la levure avant d’être transplanté dans une cellule receveuse. La levure sert d’hôte d’accueil temporaire pour modifier le génome de la bactérie. Cette approche novatrice ouvre de nombreuses perspectives dans le cadre du développement de la génomique fonctionnelle chez les mycoplasmes pour lesquels les outils génétiques efficaces sont peu nombreux. Le but de cette thèse a été d’adapter pour la première fois certains outils de BS à M. hominis dans le but de créer des mutants déficients pour une fonction donnée. Pour cela, le génome de la souche type de M. hominis PG21 (665 kb) a été cloné dans la levure Saccharomyces cerevisiae par « Transformation-Associated Recombination cloning » (TAR-cloning). Deux clones (B3-2 et B3-4) de levure possédant le génome complet de M. hominis ont été validés par analyse en PCR simplex, PCR multiplex et électrophorèse en champs pulsé (PFGE). Ces clones levures ont ensuite été propagés en milieu sélectif durant 180 générations (30 passages), afin d’évaluer la stabilité du génome bactérien dans son hôte. Cette expérience a montré que (i) si la taille du génome de M. hominis ne variait pas au cours des premiers passages, elle diminuait progressivement à partir du dixième passage (≈60 générations), et que (ii) les zones du génome enrichies en séquence répétées étaient préférentiellement perdues. En tenant compte de ces résultats, le génome de M. hominis a été modifié chez le clone B3-4 par la technique « Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 » (CRISPR/Cas9) lors de passages précoces. Des clones de S. cerevisiae possédant un génome de M. hominis PG21 complet délété du gène vaa, codant une protéine d’adhésion majeure, ont été ainsi produits. La dernière étape de cette approche consistait à transplanter le génome modifié dans une cellule receveuse de M. hominis ou de Mycoplasma arthritidis, espèce phylogénétiquement la plus proche de M. hominis. Aucun protocole de transformation de M. hominis n’étant disponible au début de nos travaux, cette étape constituait un verrou majeur dans la mise en place des outils de BS chez cette espèce. Ce verrou a été en partie levé puisqu’une méthode de transformation de M. hominis basée sur du polyéthylène glycol (PEG) et mettant en jeu le plasposon pMT85 (plasmide contenant un transposon conférant la résistance à la tétracycline) a été mise au point au laboratoire. Cette technique de transformation, développée pour la souche de référence M. hominis M132 (745 kb) reste encore peu efficace ; elle est néanmoins reproductible et a permis d’obtenir des mutants d’intérêt de M. hominis. Le transformant n°28-2 a, ainsi, été muté dans le gène Mhom132_2390, codant le précurseur de la protéine P75, une adhésine putative de M. hominis. Le séquençage des génomes complets d’autres transformants a révélé l’insertion de multiples copies du transposon et la présence d’évènements de duplication et d’inversion de larges fragments d’ADN dans au moins deux génomes de M. hominis
Mycoplasma hominis is an opportunistic human pathogen responsible for genital and neonatal infections. Genetically modifying this bacterium is necessary to understand the virulence and infection mechanisms of this pathogen. There is currently no effective molecular tool to engineer the genome of this bacterium, limiting research on its pathogenicity and its peculiar metabolism based on arginine.New technologies have recently emerged in the field of Synthetic Biology (BS), offering new perspectives for the study of mycoplasmas by allowing large scale genome modifications and the production of mutant strains. Work at the J. Craig Venter Institute (JCVI, USA) has shown that the genome of related mycoplasmas can be cloned and manipulated in yeast before being transplanted into a recipient cell. The yeast serves as a temporary host to modify the genome of the bacterium. This innovative approach opens many perspectives in the development of functional genomics in mycoplasmas for which there are few effective genetic tools. The goal of this thesis was to adapt a number of BS tools to M. hominis for the first time, in order to create mutants deficient for a given function. To achieve this goal, the genome of the M. hominis type strain PG21 (665 kb) was cloned into the yeast Saccharomyces cerevisiae by Transformation-Associated Recombination cloning (TAR-cloning). Two yeast clones (B3-2 and B3-4) possessing the complete genome of M. hominis were validated by simplex PCR, multiplex PCR and Pulsed Field Gel Electrophoresis (PFGE) analyses. These yeast clones were then propagated in a selective medium for 180 generations (30 passages) to evaluate the stability of the bacterial genome in its host. This experiment showed that (i) the size of the genome of M. hominis did not change during the first passages, it decreased progressively from the tenth passage (≈60 generations), and (ii) the enriched genome areas in repeated sequence were preferentially lost. Thus, the genome of M. hominis was modified in the B3-4 clone at early passages using the Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 (CRISPR/Cas9) technology. Yeast clones with a complete M. hominis PG21 genome with a deleted vaa gene, encoding a major adhesion protein, were produced using this approach. The final step of this approach was to transplant the modified genome into a recipient cell of M. hominis or Mycoplasma arthritidis, the species phylogenetically closest to M. hominis. As no M. hominis transformation protocol was available at the beginning of our work, this step constituted a major obstacle in the implementation of BS tools in this species. This barrier has been partially lifted since a method of transformation of M. hominis based on polyethylene glycol (PEG) and involving the plasposon pMT85 (plasmid carrying a transposon conferring resistance to tetracycline) has been developed in the laboratory. This transformation technique, developed for the reference strain M. hominis M132 (745 kb) still remains not very efficient; it is nevertheless reproducible and allowed to obtain M. hominis mutants of interest. The Mhom132_2390 gene, encoding the precursor of the P75 protein, a putative adhesin of M. hominis, was effectively mutated in transformant No. 28-2. Complete genome sequencing of other transformants revealed the insertion of multiple copies of the transposon and the presence of duplication and inversion of large DNA fragments within at least two M. hominis genomes.In conclusion, this data has opened the way for the development and transposition of existing genetic modification approaches to M. hominis, previously considered as a genetically intractable bacterium

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Mitchell, Laura. "Metal organic frameworks as Lewis acid catalysts". Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/6392.

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Lewis acids are widely used in the pharmaceutical industry, generally homogeneously, to perform reactions such as C-C or C=N bond formation and acetalisation. Typically, metal salts such as those of Ti, Fe and especially Sc are used, the last typically as the triflate. Metal organic frameworks (MOFs) containing such metals should act as heterogeneous, removable and reusable catalysts for similar reactions if they can be prepared in stable forms and with large, open pores and metal cation sites that can be rendered coordinatively unsaturated. Families of novel MOFs with different structure types and cations have therefore been prepared and their activity has been examined in carbonyl ene C-C bond forming reactions, Friedel-Crafts-Michael additions and in imine formation reactions. Their activities have been compared with those of the well-known HKUST-1(Cu), MIL-100(Fe) and MIL-101(Cr) solids examined as catalysts previously. In particular, divalent transition metal bisphosphonates and dicarboxylates with pore sizes from 10 – 20 Å and scandium carboxylates (MIL-68(Sc), MIL-88D(Sc), MIL-100(Sc), MIL-101(Sc)) have been tested. Synthetic procedures were optimised according to commercial constraints for the known MOFs STA-12(Ni) and MIL-100(Sc). While good activities are observed for Ni-based MOFs and in a number of the scandium-based solids, MIL-100(Sc) is by far the best Lewis acid catalyst for a range of reactions. In particular, MIL-100(Sc) is very active even when used without pre-dehydration, is readily recyclable with minor loss of activity and shows fully heterogeneous activity. It outperforms both MIL-100(Fe) and MIL-101(Cr), each commonly reported as versatile catalysts in the literature. Careful synthesis of bulky substrates shows that the activity is derived from reactions within the internal pore system. Furthermore, MIL-100(Sc) is able to perform tandem reactions - such as dehydration followed by carbonyl ene reaction - in which the Lewis acid sites catalyse two steps. The Lewis acidic sites of the excellent Lewis acid catalyst MIL-100(Sc) has been examined in detail by in situ IR using adsorption of CO and CD₃CN as probe molecules and compared with other MIL-100 materials. The work has been extended to the examination of MOFs containing two different metals, by substitutional approaches within the metal nodes (e.g. Sc-Al, Sc-Fe, Sc-Cr, Sc-Ni, Sc-Co within the trimeric M₃O(O₂C-)₆ nodes of MIL-100). In addition, series of Sc-Fe MIL-100 materials have been prepared that contain α-Fe₂O₃ nanoparticles in the pores of the structure. These composites show higher specific catalytic activity for Lewis acid catalysis than MIL-100(Sc), even though some scandium has been replaced with iron: the origin of this behaviour is discussed. MIL-100(Sc/Fe) has also been explored as a bifunctional catalyst in tandem Friedel-Crafts-oxidation reactions. MIL-100(Sc₆₀/Fe₄₀) was found to give exceptionally high conversions in the Friedel-Crafts-oxidation tandem reaction of 2-methyl indole and ethyl trifluoropyruvate to form a ketone, outperforming the many other materials tested and giving the best balance of the two different types of catalytic sites required to catalyse the reaction. MIL-100(Sc) has also been prepared containing 50% of mono-fluorinated trimesate ligands in the framework for the first time. This fluorinated MIL-100(Sc) has been post-synthetically modified by addition of a di-phenylphosphino group as confirmed by solid state NMR. This can act as a starting point for the future generation of MOF-supported metal phosphine catalysts.

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Dempster, Nicola M. "Synthetic modification and characterisation of poly(styrene-co-divinylbenzene) resins and their possible application in environmental analysis". Thesis, Liverpool John Moores University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590096.

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Chromatographic micro-beads of the hypercrosslinked poly(styrene-co-divinylbenzene) (PS-OV8) chromatographic adsorbent Amberchrom CG161m, were modified by introduction of polar functional groups using Friedel-Crafts acylation and Bronsted-Lowry nitrating reactions. The Amberchrom CG161m™ microbeads were functionalised by attachment of acetyl, chloroacetyl, dichloroacetyJ, methoxyacetyl, bromoacetyl, nitro and amino groups. Introduction of polar moieties enhances the etridency of the solid phase extraction (SPE) resins by improving surface contact with aqueous samples, increasing capacity and extraction of polar compounds and facilitating greater recovery of strongly held hydrophobic contaminants due to the hydrophilic-lipophilic balance of the adsorbent surface. Fourier-transform infrared spectroscopy (FT-IR), micro-elemental analysis (CHN), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), x-ray fluorescence (XRF), scanning electron microscopy (SEM) and nitrogen adsorption analyses (BET/BJI-I/DFT) were used to characterise the physico-chemical parameters of the novel functionalised resins and confirm success of the chemical reactions. The pristine Amberchrom microbeads, chemically modified PS-DVB adsorbents and bulk commercial resins (Biotage 1ST Env+TM , 1ST C18 EC and Waters Oasis HLB) were packed into analytical columns and solute-sorbent interactions evaluated from retention parameters of interrogative analytes using HPLC. Differences in physical and chemical characteristics of the SPE packing materials were identified and their influences on solute retention parameters and capacities assessed. An objective assessment of solute retention mechanisms on funclionalised sorbents was conducted in sifica using data reduction techniques and chemometric models from HPLC evaluation of solutes based on substituted benzenes. Data reduction techniques included Genetic Factor Approximation (GFA), Principal Component Analysis (PCA) and Factor Analysis (FA), with quantitative structure retention relationships (QSRR) and stepwise multi-linear regression analysis (Stepwise-MLRA) employed for computational modelling. The chemometric elucidation of sorption and elution mechanisms provided further insight into the chromatographic system and clarified perspectives and benefits of the polar functionalised resins and their potential as SPE resins. Chloroacetylated, dichloroacetyJated and methoxyacetylated PS-OVB resins were identified as adsorbents with favourable characteristics for extraction of polar analytes. Chloroacetylated and dichloroacetylated-PS-OVB sorbents also demonstrated a chemical flexibility that could be manipulated to enable mixed-mode retention for multi-residue extraction methods

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Thenna, Hewa Kosala R. S. "Applications Focused Synthetic Modification on Photoremovable Protecting Groups (PRPG) & Photochemical Analysis on Organic Azides and Isoxazoles". University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511858669354976.

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Bellancini, Michele. "Engineering the synthesis of lantibiotics in e. Coli by combining the cynnamicin and nisin modification systems". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8625/.

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I lantibiotici sono molecole peptidiche prodotte da un gran numero di batteri Gram-positivi, posseggono attività antibatterica contro un ampio spettro di germi, e rappresentano una potenziale soluzione alla crescente problematica dei patogeni multi-resistenti. La loro attività consiste nel legame alla membrana del bersaglio, che viene quindi destabilizzata mediante l’induzione di pori che determinano la morte del patogeno. Tipicamente i lantibiotici sono formati da un “leader-peptide” e da un “core-peptide”. Il primo è necessario per il riconoscimento della molecola da parte di enzimi che effettuano modifiche post-traduzionali del secondo - che sarà la regione con attività battericida una volta scissa dal “leader-peptide”. Le modifiche post-traduzionali anticipate determinano il contenuto di amminoacidi lantionina (Lan) e metil-lantionina (MeLan), caratterizzati dalla presenza di ponti-tioetere che conferiscono maggior resistenza contro le proteasi, e permettono di aggirare la principale limitazione all’uso dei peptidi in ambito terapeutico. La nisina è il lantibiotico più studiato e caratterizzato, prodotto dal batterio L. lactis che è stato utilizzato per oltre venti anni nell’industria alimentare. La nisina è un peptide lungo 34 amminoacidi, che contiene anelli di lantionina e metil-lantionina, introdotti dall’azione degli enzimi nisB e nisC, mentre il taglio del “leader-peptide” è svolto dall’enzima nisP. Questo elaborato affronta l’ingegnerizzazione della sintesi e della modifica di lantibiotici nel batterio E.coli. In particolare si affronta l’implementazione dell’espressione eterologa in E.coli del lantibiotico cinnamicina, prodotto in natura dal batterio Streptomyces cinnamoneus. Questo particolare lantibiotico, lungo diciannove amminoacidi dopo il taglio del leader, subisce modifiche da parte dell’enzima CinM, responsabile dell’introduzione degli aminoacidi Lan e MeLan, dell’enzima CinX responsabile dell’idrossilazione dell’acido aspartico (Asp), e infine dell’enzima cinorf7 deputato all’introduzione del ponte di lisinoalanina (Lal). Una volta confermata l’attività della cinnamicina e di conseguenza quella dell’enzima CinM, si è deciso di tentare la modifica della nisina da parte di CinM. A tal proposito è stato necessario progettare un gene sintetico che codifica nisina con un leader chimerico, formato cioè dalla fusione del leader della cinnamicina e del leader della nisina. Il prodotto finale, dopo il taglio del leader da parte di nisP, è una nisina completamente modificata. Questo risultato ne permette però la modifica utilizzando un solo enzima invece di due, riducendo il carico metabolico sul batterio che la produce, e inoltre apre la strada all’utilizzo di CinM per la modifica di altri lantibiotici seguendo lo stesso approccio, nonché all’introduzione del ponte di lisinoalanina, in quanto l’enzima cinorf7 necessita della presenza di CinM per svolgere la sua funzione.

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Mohamed, Nasser Hassan [Verfasser], Jochen Stefan [Akademischer Betreuer] Gutmann i Mathias [Akademischer Betreuer] Ulbricht. "Surface Modification of Synthetic Fibers for Antibacterial Applications / Nasser Hassan Mohamed. Gutachter: Mathias Ulbricht. Betreuer: Jochen Stefan Gutmann". Duisburg, 2013. http://d-nb.info/1030475466/34.

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33

Knaggs, Jonathan David. "The modulation of Transient Receptor Potential A1 channel by natural and novel semi-synthetic compounds via non-covalent modification". Thesis, University of Hull, 2016. http://hydra.hull.ac.uk/resources/hull:15136.

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Transient Receptor Potential A1 (TRPA1) is commonly known as the detector of a broad range of noxious chemical agents both exogenous and endogenous. TRPA1 detects these chemicals through a reversible covalent modification mechanism that allows most electrophilic compounds to activate the channel; hence one of the channel’s key roles is to protect the respiratory system from harmful irritants by activating the cough reflex. It has been proposed that TRPA1 is involved in chronic inflammatory diseases of the respiratory system and has been highlighted as a potential drug target for this as well as general pain and inflammation. TRPA1 is also activated by non-covalent mechanisms, which are less well understood. I therefore aimed to gain a further understanding of non-covalent mechanisms of TRPA1 modulation via structure-activity relationship studies using several groups of diverse compounds based on existing TRPA1 agonists. The results reported have shown that compounds based on thymol, carvacrol and fenamic acid have a diverse effect on TRPA1 dependent on small alterations in structure. This highlights the delicate nature of the TRPA1 non-covalent binding sites. The derivatives tested all share one common structural feature; they all have two phenyl rings which are linked via different functional groups and different lengths. It was found that the length of the linker had an effect on the potency of the modulation of TRPA1. In addition to these results NDGA and its semi-synthetic derivative M4N were potent TRPA1 agonists, yet unlike other similar compounds do not desensitise TRPA1, possibly due to their folded structure. Throughout the results, the importance of hydrogen bonding was shown with different functional groups capable of acting as donors or acceptors. Overall the results reported expand the group of non-covalent modulators of TRPA1 and indicated important structural features that must be considered in any future TRPA1 drug development projects.

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Catli, Candan. "Novel synthetic approaches for fabrication of polymer brushes on gold surfaces via Raft polymerization: A new era for gold modification". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://hdl.handle.net/11858/00-1735-0000-002E-E353-2.

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Ågren, Jonas. "Regional Geoid Determination Methods for the Era of Satellite Gravimetry : Numerical Investigations Using Synthetic Earth Gravity Models". Doctoral thesis, KTH, Infrastructure, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-55.

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It is the purpose of this thesis to investigate different regional geoid determination methods with respect to their feasibility for use with a future GOCE satellite-only Earth Gravity Model (EGM). This includes investigations of various techniques, which involve different approximations, as well as the expected accuracy. Many, but not all, of these tasks are tested by means of Synthetic Earth Gravity Models (SEGMs). The study is limited to remove-compute-restore methods using Helmert condensation and to Sjöberg's combined approach (method with additive corrections).

First, a number of modifications of Stokes' formula are tested with respect to their compatibility with a GOCE EGM having negligible commission error. It is concluded that the least squares modification method should be preferred.

Next, two new point-mass SEGMs are constructed in such a way that the resulting models have degree variances representative for the full and topographically reduced gravity fields, respectively. These SEGMs are then used to test different methods for modified Stokes' integration and downward continuation. It is concluded that the combined method requires dense observations, obtained from the given surface anomalies by interpolation using a reduction for all known density anomalies, most notably the topography. Examples of other conclusions are that the downward continuation method of Sjöberg (2003a) performs well numerically.

To be able to test topographic corrections, another SEGM is constructed starting from the reduced point-mass model, to which the topography, bathymetry and isostatic compensation are added. This model, which is called the Nordic SEGM, is then applied to test one strict and one more approximate approach to Helmert's condensation. One conclusion here is that Helmert's 1st method with the condensation layer 21 km below sea level should be preferred to Helmert's 2nd condensation strategy.

The thesis ends with a number of investigations of Sjöberg's combined approach to geoid determination, which include tests using the Nordic SEGM. It is concluded that the method works well in practice for a region like Scandinavia. It is finally shown how the combined strategy may preferably be used to estimate height anomalies directly.

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Reyna, González Emmanuel [Verfasser], i Elke [Akademischer Betreuer] Dittmann. "Engineering of the microviridin post-translational modification enzymes for the production of synthetic protease inhibitors / Emmanuel Reyna González ; Betreuer: Elke Dittmann-Thünemann". Potsdam : Universität Potsdam, 2017. http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-406979.

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Hughes, David. "The local free volume and other properties of synthetic and biopolymers : the effect of chemical and modification, matrix composition and environmental conditions". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702746.

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The focus of this thesis is the investigation of changes in the local free volume and related properties in complex polymeric systems of immediate interest to industry using positron annihilation lifetime spectroscopy (PALS) in conjunction with a number of complementary techniques. PALS and differential scanning calorimetry (DSC) were used to investigate the temperature dependence of the local free volume hole size distribution parameters and the thermal transitions in a series of poly( dimethylsiloxane) based elastomers where meta-carborane was incorporated into the elastomer network via two methods. The presence of significant phase separation in the so-called hybrid elastomers is confirmed by DSC and PALS, suggesting that this is not a suitable method for the production of elastomers for industrial application. By cross-linking a single component system, amorphous monomodal elastomers can be prepared that are not susceptible to crystallisation, making them ideal candidates for high-performance elastomers. The features observed in the local free volume distribution parameters from PALS agree well with the transitions measured by DSC, and are shown to be sensitive to the presence of crystallinity due to the coexistence of the rigid and mobile amorphous fractions. Incorporating ortho-carborane in to the hard segment of a model polyurethane as a chain extender is seen to reduce the level of hard segment - soft segment phase separation and promote the evolution of a mixed amorphous phase. The carborane is seen to reduce the level of hard segment ordering via disruption of the formation of hard segment hydrogen bonds, ultimately converting a bimodal/highly heterogeneous free volume environment into a more uniform amorphous phase with reduced local free volume properties. This study suggests that the micro structure, and thus the macroscopic physical properties, of these polyurethanes can be "tuned" via the level of carborane inclusion. The morphology, phase behaviour and local free volume of complex microencapsulation formulations consisting of hydrophobically modified food starch (MFS) and sucrose were studied as formulation composition and water content was varied. Significant phase separation was observed between the MFS and the sucrose, the compositions of the phases were observed to change significantly when part of the blend passes into the rubbery state. The local free volume from PALS, the first such study in a real and multi-component encapsulation matrix, exhibits features seen for much simpler model carbohydrate systems, displaying a complex dependence of blend water content and a reduction in the average hole volume as the sucrose content is increased. It is predicted that the encapsulation performance of these blends will be dictated and limited by the presence of phase separation.

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Reyna, González Emmanuel [Verfasser], i Elke [Akademischer Betreuer] Dittmann-Thünemann. "Engineering of the microviridin post-translational modification enzymes for the production of synthetic protease inhibitors / Emmanuel Reyna González ; Betreuer: Elke Dittmann-Thünemann". Potsdam : Universität Potsdam, 2017. http://d-nb.info/1218403276/34.

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Wang, Zhengbang [Verfasser], i P. [Akademischer Betreuer] Roesky. "Liquid-Phase Epitaxial Growth of Highly Oriented and Crystalline MOF Thin Films: Post-Synthetic Modification and Different Applications / Zhengbang Wang. Betreuer: P. Roesky". Karlsruhe : KIT-Bibliothek, 2015. http://d-nb.info/1067497005/34.

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Epley, Charity Cherie. "Developing Photo-responsive Metal-Organic Frameworks towards Controlled Drug Delivery". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/78346.

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The development of therapeutic drugs or drug systems that enhance a cancer patient's quality of life during treatment is a primary goal for many researchers across a wide range of disciplines. Many investigators turn to nanoparticles (~50-200 nm in size) that tend to accumulate in tumor tissues in order to deliver active drug compounds to specific sites in the body. This targeted delivery approach would reduce the total body effects of current cancer drugs that result in unwanted (sometimes painful and even fatal) side effects. One of the main obstacles however, is ensuring that drugs incorporated into the nanoparticles are anchored such that premature drug release is prohibited. Also, while it is important to ensure strong drug-nanocarrier interactions, the nanocarrier must be able to release the drug when it has reached its biological target. We have developed a nanocarrier that provides a platform for drug systems that could achieve this drug release via the use of a light "trigger". Metal-Organic Frameworks (MOFs) are a relatively new class of often highly porous materials that act as "sponges" for the absorption of various small molecules. MOFs are so named because they consist of metal clusters that are linked by organic compounds to form networked solids that are easily tuned based on the choice of metal and organic "linker". We have developed a MOF nanocarrier incorporating benign zirconium (IV) metal clusters bridged by an organic component that changes shape when illuminated with a light source. The resulting material is therefore not stable upon irradiation due to the organic linker shape change that disturbs the MOF structure and causes it to degrade. When loaded with drugs, this photo-enhanced degradation results in the release of the cargo thereby, providing a handle on controlling drug release with the use of a light trigger. We have demonstrated that in the presence of the MOF nanocarrier incorporating 5-fluorouracil (a clinically available cancer drug), very low toxicity to human breast cancer cells is observed in the dark, however, cell death occurs in the presence of a light source. These reports offer a model MOF nanocarrier system that could be used to incorporate various drugs and therefore tune the system to an individual patient's needs. Furthermore, we also developed a material that is capable of providing magnetic resonance imaging (MRI) contrast by changing the metal to manganese (II). MRI contrast agents are compounds that serve to either darken or brighten an MRI image based on the agent used and therefore they aid in clinical diagnosis by making internal abnormalities easier to spot. Currently gadolinium (III) complexes are the most widely used contrast agents; however, the toxicity of gadolinium (III) has been shown to be responsible for the development of nephrogenic systemic fibrosis in some patients. This manganese material has also shown useful for the attachment of fluorescent dyes that can aid in the benchtop optical diagnosis of biopsies. These reports provide a basis for developing ways to offer controlled drug delivery in cancer patients and to aid in cancer diagnosis using MOF materials, in an effort to reach the goals of comfortable cancer treatment.
Ph. D.

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Wyss, Sarah Christine. "Design of a Cross-Domain Quorum Sensing Pathway for Algae Biofuel Applications". Ohio University Honors Tutorial College / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1367239424.

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42

Islamoglu, Timur. "SYSTEMATIC POSTSYNTHETIC MODIFICATION OF NANOPOROUS ORGANIC FRAMEWORKS AND THEIR PERFORMANCE EVALUATION FOR SELECTIVE CO2 CAPTURE". VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4264.

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Porous organic polymers (POPs) with high physicochemical stability have attracted significant attention from the scientific community as promising platforms for small gas separation adsorbents. Although POPs have amorphous morphology in general, with the help of organic chemistry toolbox, ultrahigh surface area materials can be synthesized. In particular, nitrogen-rich POPs have been studied intensively due to their enhanced framework-CO2 interactions. Postsynthetic modification (PSM) of POPs has been instrumental for incorporating different functional groups into the pores of POPs which would increase the CO2 capture properties. We have shown that functionalizing the surface of POPs with nitro and amine groups increases the CO/N2 and CO2/CH4 selectivity significantly due to selective polarization of CO2 molecule. In addition, controlled postsynthetic nitration of NPOF-1, a nanoporous organic framework constructed by nickel(0)-catalyzed Yamamoto coupling of 1,3,5-tris(4-bromophenyl)benzene, has been performed and is proven to be a promising route to introduce nitro groups and to convert mesopores to micropores without compromising surface area. Reduction of the nitro groups yields aniline-like amine-functionalized NPOF-1-NH2. Adequate basicity of the amine functionalities leads to modest isosteric heats of adsorption for CO2, which allow for high regenerability. The unique combination of high surface area, microporous structure, and amine-functionalized pore walls enables NPOF-1-NH2 to have remarkable CO2 working capacity values for removal from landfill gas and flue gas. Benzimidazole-linked polymers have also been shown to have promising CO2 capture properties. Here, an amine functionalized benzimidazole-linked polymer (BILP-6-NH2) was synthesized via a combination of pre- and postsynthetic modification techniques in two steps. Experimental studies confirm enhanced CO2 uptake in BILP-6-NH2 compared to BILP-6, and DFT calculations were used to understand the interaction modes of CO2 with BILP-6-NH2. Using BILP-6-NH2, higher CO2 uptake and CO2/CH4 selectivity was achieved compared to BILP-6 showing that this material has a very promising working capacity and sorbent selection parameter for landfill gas separation under VSA settings. Additionally, the sorbent evaluation criteria of different classes of organic polymers have been compared in order to reveal structure-property relationships in those materials as solid CO2 adsorbents.

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Somero, John Ryan. "Structure and Persistence of Surface Ship Wakes". Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/101989.

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It has long been known that ship wakes are observable by synthetic aperture radar. However, incomplete physical understanding has prevented the development of simulation tools that can predict both the structure and persistence of wakes in the ocean environment. It is the focus of this work to develop an end-to-end multi-scale modeling-and-simulation methodology that captures the known physics between the source of disturbance and the sensor. This includes turbulent hydrodynamics, free-surface effects, environmental forcing through Langmuir-type circulations, generation of surface currents and redistribution of surface-active substances, surface-roughness modification, and simulation of the signature generated by reflection and scattering of electromagnetic waves from the ocean surface. The end-to-end methodology is based upon several customized computational fluid dynamics solvers and empirical models which are linked together. The unsteady Reynolds-averaged Navier-Stokes equations, including models for the Craik-Leibovich vortex force and near surface Reynolds-stress anisotropy, are solved at full-scale Reynolds and Froude numbers on domains that extend tens of kilometers behind the ship. A parametric study is undertaken to explore the effects of ship heading, ship propulsion, ocean-wave amplitude and wavelength, and the relative importance of Langmuir-type circulations vs. near-surface Reynolds-stress anisotropy on the generation of surface currents that are transverse to the wake centerline. Due to the vortex force, the structure of the persistent wake is shown to be a function of the relative angle between the ambient long-wavelength swell and the ship heading. Ships operating in head seas observe 1-3 streaks, while ships operating in following seas observe 2 symmetric streaks. Ships operating in calm seas generate similar wakes to those in following seas, but with reduced wake width and persistence. In addition to the structure of the persistent wake, the far wake is shown to be dominated by ship-induced turbulence and surface-current gradients generating a wide center wake. The redistribution of surface-active substances by surface currents is simulated using a scalar-transport model on the ocean surface. Simulation of surface-roughness modification is accomplished by solving a wave-action balance model which accounts for the relative change in the ambient wave-spectrum by the surface currents and the damping-effects of surface-active substances and turbulence. Simulated returns from synthetic aperture radar are generated with two methods implemented. The first method generates a perfect SAR image where the instrument and platform based errors are neglected, but the impact of a randomized ocean field on the radar cross section is considered. The second method simulates the full SAR process including signal detection and processing. Comparisons are made to full-scale field experiments with good agreement between the structure of the persistent wake and observed SAR imagery.
1
It has long been known that ship wakes are observable by synthetic aperture radar. However, incomplete physical understanding has prevented the development of simulation tools that can predict both the structure and persistence of wakes in the ocean environment, which is critical to understanding both the design and operation of maritime remote sensors as well as providing tactically relevant operational guidance and awareness of the maritime domain. It is the focus of this work to develop an end-to-end multi-scale modeling-and simulation methodology that captures the known physics between the source of disturbance and the sensor. This includes turbulent hydrodynamics, free-surface effects, environmental forcing, generation of surface currents and redistribution of surface-active substances, surface-roughness modification, and simulation of the signature from the ocean surface. The end-to-end methodology is based upon several customized computational fluid dynamics solvers and empirical models. The unsteady Reynolds-averaged Navier-Stokes equations, including models to account for environmental effects and near-surface turbulence, are solved at full-scale on domains that extend tens of kilometers behind the ship. A parametric study is undertaken to explore the effects of ship heading, ship propulsion, ocean-wave amplitude and wavelength, and the relative importance of environmental forcing vs. near-surface turbulence on the generation of surface currents that are transverse to the wake centerline. Due to the environmental forcing, the structure of the persistent wake is shown to be a function of the relative angle between the ambient long-wavelength swell and the ship heading. Ships operating in head seas observe 1-3 streaks, while ships operating in following seas observe 2 symmetric streaks. Ships operating in calm seas generate similar wakes to those in following seas, but with reduced wake width and persistence. In addition to the structure of the persistent wake, the far wake is shown to be dominated by ship-induced turbulence and surface-current gradients generating a wide center wake. The redistribution of surface films by surface currents is simulated using a scalar-transport model on the ocean surface. Simulation of surface-roughness modification is accomplished by solving a wave-action-balance model which accounts for the relative change in the ambient surface profile by the surface currents and the damping-effects of surface-active substances and turbulence. Simulated returns from synthetic aperture radar are generated with two methods implemented. The first method generates a perfect SAR image where the instrument and platform based errors are neglected, but the impact of a randomized ocean field on the radar cross section is considered. The second method simulates the full SAR process including signal detection and processing. Comparisons are made to full-scale field experiments with good agreement between the structure of the persistent wake and observed SAR imagery.

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Joly, Jean-Patrick. "Conception, synthèse et étude de nouvelles molécules bioactives. Propriétés antivirales et antimélanome". Thesis, Nice, 2013. http://www.theses.fr/2013NICE4129.

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Malgré des progrès importants réalisés ces dernières années, la lutte contre les infections virales (SIDA, hépatites etc.) et les cancers demeurent un problème de santé mondiale. Ce bref bilan met en évidence la nécessité de développer de nouvelles molécules pour contourner les limites des traitements disponibles actuellement. Cette thèse, articulée autour de trois grands thèmes, s’inscrit dans ce contexte. Nous avons d’abord mis au point de manière rationnelle de nouveaux ligands d’ARN capables de se lier sélectivement à certaines structures secondaires de type tige-boucle ou tige-renflement de l’ARN TAR du VIH-1. Ces ligands interagissent avec l’ARN grâce à l’action coopérative de deux motifs de reconnaissance : (i) une nucléobase modifiée qui peut reconnaitre spécifiquement une paire de base de l’ARN et (ii) des acides aminés qui agissent avec les bases non appariées de l’ARN. Ces deux motifs sont reliés grâce à une matrice aliphatique (ligands non nucléosidiques) ou une matrice 2-désoxyribose (ligands nucléosidiques). Des études biophysiques et biologiques ont été menés en collaboration avec l’équipe du Dr. L. Briant (CEAPBS, UMR5236-CNRS) pour connaitre leur activité antivirale et leur site d’interaction sur la cible. Nous avons ensuite développé des molécules de type benzènesulfonamide thiazoles pour cibler le mélanome résistant aux inhibiteurs de B-Raf. Des modulations effectuées sur ce squelette nous ont permis d’établir des relations structure/activité, en collaboration avec l’équipe de Dr. S. Rocchi (C3M, INSERM U895). Enfin, nous avons développé une stratégie de modification post-synthétique d’oligonucléotides en position anomérique par réaction clic
Despite significant progress made in recent years, the fight against viral infections (AIDS, Hepatitis, etc.) and cancer remains a global health problem. This brief summary underlines the need for new compounds in order to overcome the limitations of currently available drugs. To this end, the main objective of this thesis is to address these issues by the investigation of three major research projects. We first developed new RNA ligands that selectively bind to RNA secondary structures such as the stem-loop or the stem-bulge of HIV-1 TAR RNA. These ligands interact with RNA thanks to the presence of two RNA binding domains acting in a cooperative manner: (i) a modified nucleobase that can specifically recognize an RNA base pair and (ii) basic amino acids that interact with strong affinity with surrounding free RNA nucleobases. These two patterns are connected by an aliphatic matrix (non-nucleoside ligands) or a 2-desoxyribose matrix (nucleoside-based ligands). Biophysical and biological studies were conducted in collaboration with the team of Dr. L. Briant (CEAPBS, UMR5236-CNRS) in order to study their antiviral activity and their mode of action. We next developed new bioactive molecules featuring a thiazole benzenesulfonamide scaffold to target melanoma cells resistant to B-Raf inhibitors. The modular synthesis of a large number of analogs allowed us to establish the structure/activity relationships, in collaboration with the team of Dr. S. Rocchi (C3M, INSERM U895). Finally, we developed a straightforward and convenient strategy for post-synthetic modification of oligonucleotides at the anomeric position using click chemistry

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Muwonge, Abubaker. "Detection Of Genetically Modified Potatoes By The Polymerase Chain Reaction". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605783/index.pdf.

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Quite a number of important crops have been genetically modified with genes for agronomically important traits, such as insect and viral resistance. As the numbers of genetically modified foods continue to increase on the market, the need for rapid development of GMO detection methods is indispensable. This study was carried out to detect if genetically modified potatoes exist on food market in Turkey. Thirty samples from different places were collected. Using a DNA based PCR method, potato samples were examined for the presence of 35S promoter, Nos terminator, neomycin phosphotransferase (nptII) genes, and synthetic cry3A gene which is the general transgene in all approved Newleaf transgenic potato lines. The experimental design of this study was to detect Newleaf insect resistant lines. In 11 samples at least one genetic element was detected. Sample R from Ankara has shown to be belonging to Newleaf insect resistant lines. Since 35S promoter was not detected in samples M3, 14 and F1, it is proposed that they are belonging to Newleaf virus and insect resistant lines (Newleaf plus or Newleaf Y). Although Nos terminator was not detected in samples H2, Z2 and D, cry3A fragments amplified in those samples have been verified that they are from the synthetic cry3A regions of Newleaf lines. The detected synthetic cry3A gene in GM potatoes was amplified by specific primers, which cannot amplify Bacillus thuringiensis tenebrionis natural cry3A gene. In addition, the authenticity of the synthetic cry3A PCR products were confirmed by both sequencing and restriction digestions. Our results showed that genetically modified Newleaf potatoes exist in food market in Turkey. Further studies by accredited laboratories are strongly recommended.

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Monneau, Yoan. "Etude des modifications post-traductionnelles des histones : l’analyse structuro-fonctionnelle d'une peptidyl-prolyl isomérase et la production semi-synthétique d’une protéine acétylée". Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21900/document.

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L'unité structurale de la chromatine, nommée nucléosome, est composée d'un double brin d'ADN enroulé autour d'un octamère d'histone, et subit une pléthore de modifications post-traductionnelles. Les conséquences biologiques de l’acétylation des lysines et de l’isomérisation des liaisons peptidyl-prolyl ont été étudiées à travers une analyse à l’échelle atomique par RMN de systèmes d'intérêt reconstitués in vitro. Les liaisons peptidyl-prolyl du domaine N-terminal de l'histone H3 sont substrats in vitro d’une isomérase chez S. cerevisiae nommée Fpr4p, laquelle exerce un contrôle catalyse-dépendant de la transcription. La résolution de la structure du domaine catalytique de Fpr4p, à partir de contraintes géométriques mesurées par RMN, révéla un domaine canonique de la famille FKBP (FK506-binding protein). Grâce à l'analyse de la séquence primaire et aux expériences RMN, nous proposons un modèle structural préliminaire de Fpr4p entière. L'analyse fonctionnelle est réalisée grâce à trois décapeptides construits à partir de la séquence primaire de H3 chez S. cerevisiae. Ils sont tous substrats de Fpr4p et la catalyse est équivalente pour Pro16 et Pro30. La proportion à l'équilibre du conformère cis fut déterminée pour les trois peptides et celle-ci n'est pas affectée par l'activité catalytique de Fpr4p. Les structures en solution des substrats en conformation trans ont été résolues par spectroscopie RMN, et seront utilisées pour des appariements moléculaires in silico sur le domaine catalytique de Fpr4p. Pour étudier le rôle biologique de l'acétylation des histones, une méthodologie de production de protéines acétylées a été développée. Le protocole repose sur la mutation d'une lysine en cystéine d'une protéine recombinante, suivie d'une alkylation contrôlée exploitant la nucléophilie du groupe thiol préalablement introduit. La production de l'agent alkylant adéquat est simple, rapide, réalisable dans un laboratoire de biologie et permet différents marquages isotopiques du groupe acétyle. L'alkylation d'une protéine repliée fut réalisée avec succès en conditions natives. Le dimère d'histone H2A-H2B, un intermédiaire de l'assemblage du nucléosome et siège d'acétylation in vivo, fut reconstruit in vitro. Les déplacements chimiques des domaines N et C-terminaux de H2A sont cohérents avec un état intrinsèquement déstructuré bien que leurs dynamiques moléculaires ne soient pas équivalentes
The structural unit of chromatin, the nucleosome, is composed of double-stranded DNA wrapped around a histone octamer and is subject to a plethora of post-translational modifications. The biological consequences of peptidyl-prolyl isomerization and lysine acetylation were investigated at atomic scale through analysis of in vitro reconstituted systems by NMR. Peptidyl-prolyl bonds of histone H3 N-terminal domain are substrates in vitro of an isomerase from S. cerevisiae named Fpr4p, which underlies transcriptional control dependent on its catalytic activity. The solution structure of the catalytic domain of Fpr4p was calculated based on restraints from NMR spectroscopy, and reveals a canonical catalytic domain belonging to the FK506-binding protein (FKBP) family. Based on primary sequence analysis and NMR experiments, a preliminary structural model of full length Fpr4p is also presented. Functional analyses were performed with three decapeptides designed from the primary sequence from the N-terminal tail of S. cerevisiae histone H3. All three constitute substrates of Fpr4p, with equivalent catalysis observed for Pro16 and Pro30. The equilibrium proportion of the cis-proline conformer has been determined for all three decapeptides, and these populations are unaffected by Fpr4p catalytic activity. Structural ensembles of the substrates with proline in the trans conformation were determined by using NMR spectroscopy, and will be subsequently used for in silico molecular docking onto Fpr4p. To study a second form of histone regulation, a semi-synthetic method to produce acetylated protein was developed. The protocol relies on the site-specific mutation of lysine to cysteine in recombinant proteins followed by controlled alkylation thanks to nucleophilicity of the introduced thiol. The production of the required alkylation reagent is easy, quick, and suitable for biology laboratory and allows diverse isotopic labeling within the acetyl group. Alkylation of folded proteins has also been achieved in native conditions. As one target of acetylation in vivo, the histone H2A-H2B dimer is an intermediate of nucleosome assembly and was reconstituted in vitro. Chemical shift values of the N- and C-terminal domains of H2A are in agreement with an intrinsically disordered state although they display differences in dynamic mobility

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47

Calzada, Defez Àngel. "Conveying expressivity and vocal effort transformation in synthetic speech with Harmonic plus Noise Models". Doctoral thesis, Universitat Ramon Llull, 2016. http://hdl.handle.net/10803/360587.

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Aquesta tesi s'ha dut a terme dins del Grup en de Tecnologies Mèdia (GTM) de l'Escola d'Enginyeria i Arquitectura la Salle. El grup te una llarga trajectòria dins del cap de la síntesi de veu i fins i tot disposa d'un sistema propi de síntesi per concatenació d'unitats (US-TTS) que permet sintetitzar diferents estils expressius usant múltiples corpus. De forma que per a realitzar una síntesi agressiva, el sistema usa el corpus de l'estil agressiu, i per a realitzar una síntesi sensual, usa el corpus de l'estil corresponent. Aquesta tesi pretén proposar modificacions del esquema del US-TTS que permetin millorar la flexibilitat del sistema per sintetitzar múltiples expressivitats usant només un únic corpus d'estil neutre. L'enfoc seguit en aquesta tesi es basa en l'ús de tècniques de processament digital del senyal (DSP) per aplicar modificacions de senyal a la veu sintetitzada per tal que aquesta expressi l'estil de parla desitjat. Per tal de dur a terme aquestes modificacions de senyal s'han usat els models harmònic més soroll per la seva flexibilitat a l'hora de realitzar modificacions de senyal. La qualitat de la veu (VoQ) juga un paper important en els diferents estils expressius. És per això que es va estudiar la síntesi de diferents emocions mitjançant la modificació de paràmetres de VoQ de baix nivell. D'aquest estudi es van identificar un conjunt de limitacions que van donar lloc als objectius d'aquesta tesi, entre ells el trobar un paràmetre amb gran impacte sobre els estils expressius. Per aquest fet l'esforç vocal (VE) es va escollir per el seu paper important en la parla expressiva. Primer es va estudiar la possibilitat de transferir l'VE entre dues realitzacions amb diferent VE de la mateixa paraula basant-se en la tècnica de predicció lineal adaptativa del filtre de pre-èmfasi (APLP). La proposta va permetre transferir l'VE correctament però presentava limitacions per a poder generar nivells intermitjos d'VE. Amb la finalitat de millorar la flexibilitat i control de l'VE expressat a la veu sintetitzada, es va proposar un nou model d'VE basat en polinomis lineals. Aquesta proposta va permetre transferir l'VE entre dues paraules qualsevols i sintetitzar nous nivells d'VE diferents dels disponibles al corpus. Aquesta flexibilitat esta alineada amb l'objectiu general d'aquesta tesi, permetre als sistemes US-TTS sintetitzar diferents estils expressius a partir d'un únic corpus d'estil neutre. La proposta realitzada també inclou un paràmetre que permet controlar fàcilment el nivell d'VE sintetitzat. Això obre moltes possibilitats per controlar fàcilment el procés de síntesi tal i com es va fer al projecte CreaVeu usant interfícies gràfiques simples i intuïtives, també realitzat dins del grup GTM. Aquesta memòria conclou presentant el treball realitzat en aquesta tesi i amb una proposta de modificació de l'esquema d'un sistema US-TTS per incloure els blocs de DSP desenvolupats en aquesta tesi que permetin al sistema sintetitzar múltiple nivells d'VE a partir d'un corpus d'estil neutre. Això obre moltes possibilitats per generar interfícies d'usuari que permetin controlar fàcilment el procés de síntesi, tal i com es va fer al projecte CreaVeu, també realitzat dins del grup GTM. Aquesta memòria conclou presentant el treball realitzat en aquesta tesi i amb una proposta de modificació de l'esquema del sistema US-TTS per incloure els blocs de DSP desenvolupats en aquesta tesi que permetin al sistema sintetitzar múltiple nivells d'VE a partir d'un corpus d'estil neutre.
Esta tesis se llevó a cabo en el Grup en Tecnologies Mèdia de la Escuela de Ingeniería y Arquitectura la Salle. El grupo lleva una larga trayectoria dentro del campo de la síntesis de voz y cuenta con su propio sistema de síntesis por concatenación de unidades (US-TTS). El sistema permite sintetizar múltiples estilos expresivos mediante el uso de corpus específicos para cada estilo expresivo. De este modo, para realizar una síntesis agresiva, el sistema usa el corpus de este estilo, y para un estilo sensual, usa otro corpus específico para ese estilo. La presente tesis aborda el problema con un enfoque distinto proponiendo cambios en el esquema del sistema con el fin de mejorar la flexibilidad para sintetizar múltiples estilos expresivos a partir de un único corpus de estilo de habla neutro. El planteamiento seguido en esta tesis esta basado en el uso de técnicas de procesamiento de señales (DSP) para llevar a cabo modificaciones del señal de voz para que este exprese el estilo de habla deseado. Para llevar acabo las modificaciones de la señal de voz se han usado los modelos harmónico más ruido (HNM) por su flexibilidad para efectuar modificaciones de señales. La cualidad de la voz (VoQ) juega un papel importante en diferentes estilos expresivos. Por ello se exploró la síntesis expresiva basada en modificaciones de parámetros de bajo nivel de la VoQ. Durante este estudio se detectaron diferentes problemas que dieron pié a los objetivos planteados en esta tesis, entre ellos el encontrar un único parámetro con fuerte influencia en la expresividad. El parámetro seleccionado fue el esfuerzo vocal (VE) por su importante papel a la hora de expresar diferentes emociones. Las primeras pruebas se realizaron con el fin de transferir el VE entre dos realizaciones con diferente grado de VE de la misma palabra usando una metodología basada en un proceso filtrado de pre-émfasis adaptativo con coeficientes de predicción lineales (APLP). Esta primera aproximación logró transferir el nivel de VE entre dos realizaciones de la misma palabra, sin embargo el proceso presentaba limitaciones para generar niveles de esfuerzo vocal intermedios. A fin de mejorar la flexibilidad y el control del sistema para expresar diferentes niveles de VE, se planteó un nuevo modelo de VE basado en polinomios lineales. Este modelo permitió transferir el VE entre dos palabras diferentes e incluso generar nuevos niveles no presentes en el corpus usado para la síntesis. Esta flexibilidad está alineada con el objetivo general de esta tesis de permitir a un sistema US-TTS expresar múltiples estilos de habla expresivos a partir de un único corpus de estilo neutro. Además, la metodología propuesta incorpora un parámetro que permite de forma sencilla controlar el nivel de VE expresado en la voz sintetizada. Esto abre la posibilidad de controlar fácilmente el proceso de síntesis tal y como se hizo en el proyecto CreaVeu usando interfaces simples e intuitivas, también realizado dentro del grupo GTM. Esta memoria concluye con una revisión del trabajo realizado en esta tesis y con una propuesta de modificación de un esquema de US-TTS para expresar diferentes niveles de VE a partir de un único corpus neutro.
This thesis was conducted in the Grup en Tecnologies M`edia (GTM) from Escola d’Enginyeria i Arquitectura la Salle. The group has a long trajectory in the speech synthesis field and has developed their own Unit-Selection Text-To-Speech (US-TTS) which is able to convey multiple expressive styles using multiple expressive corpora, one for each expressive style. Thus, in order to convey aggressive speech, the US-TTS uses an aggressive corpus, whereas for a sensual speech style, the system uses a sensual corpus. Unlike that approach, this dissertation aims to present a new schema for enhancing the flexibility of the US-TTS system for performing multiple expressive styles using a single neutral corpus. The approach followed in this dissertation is based on applying Digital Signal Processing (DSP) techniques for carrying out speech modifications in order to synthesize the desired expressive style. For conducting the speech modifications the Harmonics plus Noise Model (HNM) was chosen for its flexibility in conducting signal modifications. Voice Quality (VoQ) has been proven to play an important role in different expressive styles. Thus, low-level VoQ acoustic parameters were explored for conveying multiple emotions. This raised several problems setting new objectives for the rest of the thesis, among them finding a single parameter with strong impact on the expressive style conveyed. Vocal Effort (VE) was selected for conducting expressive speech style modifications due to its salient role in expressive speech. The first approach working with VE was based on transferring VE between two parallel utterances based on the Adaptive Pre-emphasis Linear Prediction (APLP) technique. This approach allowed transferring VE but the model presented certain restrictions regarding its flexibility for generating new intermediate VE levels. Aiming to improve the flexibility and control of the conveyed VE, a new approach using polynomial model for modelling VE was presented. This model not only allowed transferring VE levels between two different utterances, but also allowed to generate other VE levels than those present in the speech corpus. This is aligned with the general goal of this thesis, allowing US-TTS systems to convey multiple expressive styles with a single neutral corpus. Moreover, the proposed methodology introduces a parameter for controlling the degree of VE in the synthesized speech signal. This opens new possibilities for controlling the synthesis process such as the one in the CreaVeu project using a simple and intuitive graphical interfaces, also conducted in the GTM group. The dissertation concludes with a review of the conducted work and a proposal for schema modifications within a US-TTS system for introducing the VE modification blocks designed in this dissertation.

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Yildiz, Ceylan [Verfasser], i W. [Akademischer Betreuer] Kleist. "Post-synthetic modification of mixed-linker metal-organic frameworks for the design of heterogeneous single-site catalyst materials and their application in liquid phase oxidation reactions / Ceylan Yildiz ; Betreuer: W. Kleist". Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1209199149/34.

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Nouar, Farid. "Design, Synthesis and Post-Synthetic Modifications of Functional Metal-Organic Materials". Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1725.

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Porous solids are a class of materials of high scientific and technological significance. Indeed, they have the ability to interact with atoms, ions or molecules not only at their surface but also throughout the bulk of the solid. This ability places these materials as a major class involved in many applications such as gas storage and separation, catalysis, drug delivery and sensor technology. Metal-Organic Materials (MOMs) or coordination polymers (CPs) are crystalline compounds constructed from metal ions or clusters and organic components that are linked via coordination bonds to form zero-, one-, two or three-periodic structures. Porous Metal-Organic Materials (MOMs) or Metal-Organic Frameworks (MOFs) are a relatively new class of nanoporous materials that typically possess regular micropores stable upon removal of guests. An extraordinary academic and industrial interests was witnessed over the past two decades and is evidenced by a fantastic grow of these new materials. Indeed, due to a self-assembly process and readily available metals and organic linkers, an almost infinite number of materials can, in principle, be synthesized. However, a rational design is very challenging but not impossible. In theory, MOMs could be designed and synthesized with tuned functionalities toward specific properties that will determine their potential applications. The present research involves the design and synthesis of functional porous Metal-Organic Materials that can be used as platforms for specific studies related to many applications such as for example gas storage and particularly hydrogen storage. In this manuscript, I will discuss the studies performed on existing major Metal-Organic Frameworks, namely Zeolite-like Metal-Organic Frameworks (ZMOFs) that were designed and synthesized in my research group. My research was also focused on the design and the synthesis of new highly porous isoreticular materials based on Metal-Organic Polyhedra (MOP) where desirable functionality and unique features can be introduced in the final material prior and/or after the assembly process. The use of hetero-functional ligands for a rational design toward binary or ternary net will also be discussed in this dissertation.

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Catli, Candan [Verfasser], Philipp [Akademischer Betreuer] Vana, Jörg [Gutachter] Enderlein, Konrad [Gutachter] Samwer i Annette [Gutachter] Zippelius. "Novel synthetic approaches for fabrication of polymer brushes on gold surfaces via Raft polymerization: A new era for gold modification / Candan Catli ; Gutachter: Jörg Enderlein, Konrad Samwer, Annette Zippelius ; Betreuer: Philipp Vana". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://d-nb.info/1152437712/34.

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