Дисертації з теми "Ethylene Systems"
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Mastroianni, Sergio. "New catalytic systems for the polymerisation of ethylene." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343906.
Повний текст джерелаIemsam-Arng, J. "Poly(ethylene) glycol based delivery systems for nucleic acid therapies." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1381001/.
Повний текст джерелаCheung, Adolf S. F. "Phase behavior of two binary systems containing ethylene at supercritical conditions." Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/5719.
Повний текст джерелаBeigzadeh, Daryoosh. "Long-chain branching in ethylene polymerization using combined metallocene catalyst systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/NQ52024.pdf.
Повний текст джерелаAnantharaman, Bharthwaj. "Reaction mechanisms for catalytic partial oxidation systems : application to ethylene epoxidation." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32328.
Повний текст джерелаIncludes bibliographical references.
With the rapid advances in kinetic modeling, building elementary surface mechanisms have become vital to understand the complex chemistry for catalytic partial oxidation systems. Given that there is selected experimental knowledge on surface species and a large number of unknown thermochemical, rate parameters, the challenge is to integrate the knowledge to identify all the important species and accurately estimate the parameters to build a detailed surface mechanism. This thesis presents computational methodology for quickly calculating thermodynamically consistent temperature/coverage-dependent heats of formation, heat capacities and entropies, correction approach for improving accuracy in heats of formation predicted by composite G3- based quantum chemistry methods, and detailed surface mechanism for explaining selectivity in ethylene epoxidation. Basis of the computational methodology is the Unity Bond Index- Quadratic Exponential Potential (UBI-QEP) approach, which applies quadratic exponential potential to model interaction energies between atoms and additive pairwise energies to compute total energy of an adsorbed molecule. By minimizing the total energy subject to bond order constraint, formulas for chemisorption enthalpies have been derived for surface species bound to on-top, hollow and bridge coordination sites with symmetric, asymmetric and chelating coordination structures on transition metal catalysts. The UBI-QEP theory for diatomics has been extended for polyatomic adsorbates with empirical modifications to the theory.
(cont.) Formulas for activation energies have been derived for generic reaction types, including simple adsorption, dissociation-recombination, and disproportionation reactions. Basis of the correction approach is the Bond Additivity Correction (BAC) procedures, which apply atomic, molecular and bond- wise modifications to enthalpies of molecules predicted by G3B3 and G3MP2B3 composite quantum chemistry methods available in Gaussian® suite of programs. The new procedures have improved the accuracy of thermochemical properties for open and closed shell molecules containing various chemical moieties, multireference configurations, isomers and degrees of saturation involving elements from first 3 rows of the periodic table. The detailed mechanism explains the selectivity to ethylene oxide based on the parallel branching reactions of surface oxametallacycle to epoxide and acetaldehyde. Using Decomposition Tree Approach, surface reactions and species have been generated to develop a comprehensive mechanism for epoxidation. As a result of these developments in the thesis, chemisorption enthalpies can now be estimated within 3 kcal/mol of experimental values for transition metal catalysts and enthalpies predicted by G3B3 and G3MP2B3 Gaussian methods can be corrected within 0.5 kcal/mol. Examples of heterogeneous reaction systems involving silver-catalyzed ethylene epoxidation demonstrate the effectiveness of the methodologies developed in this work.
by Bharthwaj Anantharaman.
Ph.D.
Polverari, Marco. "Dynamic and evanescent wave light scattering of poly(ethylene oxide) - latex systems." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28515.
Повний текст джерелаThese studies allowed to ascertain the presence of PEO clusters in aqueous solution. The cluster size was found to be time dependent and to vary between 0.45 $ mu$m and 0.90 $ mu$m. The clusters were found to be in a thermodynamic equilibrium with the free polymer in solution and were found to reform spontaneously after a 30 minute period following filtration.
Adsorption studies indicated that the adsorption of PEO onto latex particles is kinetically controlled and that increased surface roughness and polarity of the latex particles decreases PEO adsorption. PEO clusters in solution were found to increase the value of the effective diffusion constant, D$ rm sb{eff}$ and thus decrease the calculated hydrodynamic layer thickness.
Evanescent wave light scattering was used in conjunction with a hydrodynamic impinging jet method for the study of depositing and non-depositing colloidal systems near interfaces. For non-depositing systems a comparison of the measured particle concentration profiles to the theoretically expected particle concentration profiles, calculated from DLVO theory, was made. The agreement was found to be very good.
The deposition of bare and PEO-coated latex particles onto glass interfaces was also investigated. From the data it was found that bare and smooth latex particles adsorb much more strongly onto collector surfaces than "hairy" latex particles which have long copolymer chains, such as itachonic acid, grafted onto their surfaces. The results indicated that the thicker the adsorbed polymer layer, the stronger the steric force preventing deposition of the polymer coated colloidal particles onto the collector surface. When the combined ellipsometric layer thickness of the particles and the collector surface exceeded a critical value, found to be about 15 nm, no particle deposition onto the collector surface was possible.
Nacerodien, Mogamat Thaabit. "Investigation of polymer grade blending in Ziegler-Natta Catalysed ethylene polymerisation systems." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9122.
Повний текст джерелаPolyethylene is one of the most widely used polymers to date and it is an important commodity in a variety of fields. Most existing polyethylene plants operate on technology involving heterogeneous Ziegler-Natta catalysts. Plants often change operating conditions to produce different polymer grades; this allows them to cater to a larger polymer market. A side-effect of this practice is the unwanted formation of off-spec polymer during the grade transition periods. Numerous studies have been conducted to address the issue of off-spec polymer formation. These studies involve applying optimal control theory to minimise the grade transition time or to minimise the amount of off-spec polymer generated during the transient period. This field of study is known as grade transition optimisation. The current study aims to provide an alternative approach to addressing the problem of offspec accumulation. It is proposed that stored off-spec polymer is blended with virgin polymer to provide a saleable and desirable product. The approach might be different, but the same techniques used in grade transition optimisation are applied. Polyethylene produced using Ziegler-Natta catalysts have relatively linear chains, thus a chain length distribution coefficient is sufficient to characterise the polymer product. The number average chain length and polydispersity index are adequate representatives of this distribution for reporting the properties of a polyethylene grade. For the purpose of applying optimal control theory, a polyethylene production process model was developed to calculate these average properties using a kinetic scheme based on fundamental principles. This process model is able to predict the polymer properties under both steady-state and unsteady-state behaviour. A key feature of the model is its ability to solve the system with low computational expense due to the use of the segregation approach to link particle properties to the overall bulk phase. This is especially useful since optimisation algorithms used in optimal control theory are iterative by nature. The Differential Evolution Algorithm (DEA) was used to minimise the objective functions that were developed for the optimisation schemes due to its ability to evaluate objective functions in parallel. A model of the blending aspect of the process was developed where it was derived that the polymer moments are additive on a mass basis. Pure grades were blended in a laboratory in various mass ratios and analysed using GPC to determine their molecular weight distribution curves. It was found that the model-predicted curves and the experimentally-determined curves were an excellent match, thus validating the model. In the current study, three procedures for blending off-spec material under standard industry conditions are proposed. The first method involves the introduction of off-spec polymer on a continuous basis to the virgin polymer stream during steady-state operation.
Radcliffe, James Edward. "Discovery and development of novel P,N ligands for selective ethylene oligomerisation systems." Thesis, Durham University, 2015. http://etheses.dur.ac.uk/11301/.
Повний текст джерелаAlzamly, Ahmed. "The Role of Aluminate in the Activation of Catalytic Systems for Ethylene Oligomerization." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31024.
Повний текст джерелаHagan, Susan Anne. "Poly(lactic acid)-poly(ethylene glycol) copolymers for use as drug delivery systems." Thesis, University of Nottingham, 1998. http://eprints.nottingham.ac.uk/30646/.
Повний текст джерелаGrigorian, V. "An investigation into the characterisation of the laser-induced incandescence method for the measurement of soot in practical systems." Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/10755.
Повний текст джерелаStanley, Nicholas. "Organic, metallic and mixed catalytic systems for the synthesis of poly(ethylene terephthalate-co-isosorbide terephthalate)." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10053.
Повний текст джерелаThe objective of this thesis, in partnership with the company Roquette Frères and the French Institute of Agro-Sourced Materials (IFMAS), is to develop catalytic systems which can efficiently catalyse the polyesterification of secondary alcohols. The particular aim is to simplify the incorporation of bio-sourced monomers such as isosorbide in to polyesters like poly(ethylene terephthalate) (PET). The use of this bio-sourced monomer allows access to new properties whilst also reducing the consummation of petro-sourced derivatives, much like in the case of cyclohexane dimethanol (CHDM) or cyclobutane diol (CBDO). Chapter 1 proposes a bibliographic study on the best performing catalysts currently used for the synthesis of PET. Organocatalysts, who have been rarely studied until now for this reaction, are applied to the synthesis of poly(ethylene terephthalate-co-isosorbide terephthalate) in Chapter 2. In Chapter 3, metallic catalysts known for their use in PET synthesis are applied to the reaction separately and in bimetallic combinations. In Chapter 4, these metallic catalysts are used in combinations with the best performing organocatalysts with the aim of optimising the properties whilst also reducing the metal quantities used
Rodriguez, Joel. "Investigation of transient plasma ignition for a Pulse Detonation Engine." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FRodriguez.pdf.
Повний текст джерелаChapman, Brian G. "Study of drag reduction by zwitterionic and non-Ionic surfactants in low temperature ethylene glycol/ water recirculation systems /." Connect to this title online, 2005. http://hdl.handle.net/1811/313.
Повний текст джерелаTitle from first page of PDF file. Document formattted into pages: contains vi, 78 p.; also includes graphics. Includes bibliographical references (p. 62-63). Available online via Ohio State University's Knowledge Bank.
Miles, William Clayton. "The Design of Stable, Well-Defined Polymer-Magnetite Nanoparticle Systems for Biomedical Applications." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/28725.
Повний текст джерелаPh. D.
Lucas, Bruce. "Fundamental Modeling of Solid-State Polymerization Process Systems for Polyesters and Polyamides." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29378.
Повний текст джерелаPh. D.
Junges, Fernando. "Novel catalyst systems based on Ni(II), Ti(IV), and Cr(III) complexes for oligo-and polymerization of ethylene." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2005. http://hdl.handle.net/10183/6358.
Повний текст джерелаThe complex of Brookhart Ni(α-diimine)Cl2 (1) (α-diimine = 1,4-bis(2,6- diisopropylphenyl)-acenaphthenediimine) has been characterized after impregnation on silica (S1) and MAO-modified silicas (4.0, 8.0 and 23.0 wts.% Al/SiO2 called S2, S3 and S4, respectively). The treatment of these heterogeneous systems with MAO produces some active catalysts for the polymerization of the ethylene. A high catalytic activity has been gotten while using the system supported 1/S3 (196 kg of PE/mol[Ni].h.atm; toluene, Al/Ni = 1000, 30ºC, 60 min and atmospheric pressure of ethylene). The effects of polymerization conditions have been tested with the catalyst supported in S2 and the best catalytic activity has been gotten with solvent hexane, MAO as cocatalyst, molar ratio Al/Ni of 1000 and to the temperature of 30°C (285 kg of PE/mol[Ni].h.atm). When the reaction has been driven according to the in situ methodology, the activity practically doubled and polymers showed some similar properties. Polymers products by the supported catalysts showed the absence of melting fusion, results similar to those gotten with the homogeneous systems by DSC analysis. But then, polymers gotten with the transplanted system present according to the GPC’s curves the polydispersity (MwD) varies between 1.7 and 7.0. A polyethylene blend (BPE/LPE) was prepared using the complex Ni(α-diimine)Cl2 (1) (α-diimine = 1,4-bis(2,6-diisopropylphenyl)-acenaphthenediimine) and {TpMs*}TiCl3 (2) (TpMs* = hydridobis(3-mesitylpyrazol-1-yl)(5-mesitylpyrazol-1-yl)) supported in situ on MAO-modified silica (4.0 wts. -% Al/SiO2, S2). Reactions of polymerization of ethylene have been executed in the toluene in two different temperatures (0 and 30°C), varying the molars fraction of nickel (xNi), and using MAO as external cocatalyst. To all temperatures, the activities show a linear variation tendency with xNi and indicate the absence of the effect synergic between the species of nickel and the titanium. The maximum of activity have been found at 0°C. The melting temperature for the blends of polyethylene produced at 0 °C decrease whereas xNi increases indicating a good compatibility between phases of the polyethylene gotten with the two catalysts. The melting temperature for the blends of polyethylene showed be depend on the order according to which catalysts have been supported on the MAO-modified silica. The initial immobilization of 1 on the support (2/1/S2) product of polymers with a melting temperature (Tm) lower to the one of the polymer gotten when the titanium has been supported inicially (1/2/S2). The observation of polyethylenes gotten with the two systems (2/1/S2 and 1/2/S2) by scanning electron microscopy (SEM) showed the spherical polymer formation showing that the spherical morphology of the support to been reproduced. Are described the synthesis, the characterization and the catalytic properties for the oligomerization of the ethylene of four organometallics compounds of CrIII with ligands ([bis[2-(3,5-dimethyl-1-pyrazolyl)ethyl]amine] chromium (III) chloride (3a), [bis[2-(3,5- dimethyl-l-pyrazolyl)ethyl]benzylamine] chromium (III) chloride (3b), [bis[2-(3,5-dimethyl-lpyrazolyl) ethyl]ether] chromiun(III)chloride (3c), [bis[2-(3-phenyl-lpyrazolyl) ethyl]ether]chromiun(III)chloride (3d)). In relation of the oligomerization, at exception made of the compounds 3a, all complex of the chromium showed be active after activation with MAO and the TOF gotten have one effect differentiated to those formed with CrCl3(thf)3. The coordination of a tridentate ligand on the metallic center doesn't provoke any considerable changes on the formation of the C4 and C6, but the amount of C8 are decrease and the C10 and C12+ have increased. The Polymers produced by the catalyst 3a to 3 and 20 bar of ethylene have, according to analyses by DSC, the temperatures of fusion of 133,8 and 136ºC respectively. It indicates that in the two cases the production of high density polyethylene. The molar mass, gotten by GPC, is 46647 g/mols with MwD = 2,4 (3 bar). The system 3c/MAO showed values of TOF, activity and selectivity to different α-olefins according to the pressure of ethylene uses. Himself that shown a big sensibility to the concentration of ethylene solubilized.
Travelet, Christophe. "Supramolecular systems based on α-cyclodextrins and poly(ethylene oxide) : structure and properties of pseudo-polyrotaxanes, polyrotaxanes and sliding gels". Strasbourg, 2009. http://www.theses.fr/2009STRA6033.
Повний текст джерелаWe studied the threading process between α-cyclodextrins (α-CDs) and poly(ethylene oxide) (PEO° in water, thus leading to the formation of inclusion complexes called pseudo-polyrotaxanes (PPRs). At 30°C, we established that, in a first step, α-CDs thread onto PEO chains, forming PPR molecules. At a higher length-scale, rapid aggregation of the PPR molecules occurs and threaded α-CD-based nano-cylinders form. A higher length-scale, α-CD_based nano-cylinders associate in a Gaussian way engendering the formation of precited domains. Then, in a second step, the system undergoes its reorganization characterized by a compacity increase of the precipitated domains and forms a physical gel. Then, we studied chemical gels obtained by cross-linking PRs via their α-CDs. The chemical cross-linking reaction with divinym sulfone (DVS) does not occur in soft conditions so that highly cross-linked domains cohabit with less cross-linked ones
Huang, Chien-Chang. "The application of tetrakis(dimethylamino)ethylene chemiluminescence in characterization of the surface properties of metal oxides and reversed microemulsion systems." Diss., Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1609.
Повний текст джерелаNguyen, Ngoc Linh. "Toward Realistic DFT Description of Complex Systems: Ethylene Epoxidation on Ag-Cu Alloys and RPA Correlation in van der Waals Molecules." Doctoral thesis, SISSA, 2012. http://hdl.handle.net/20.500.11767/4699.
Повний текст джерелаPrasetyo, Eko [Verfasser], and Elias [Akademischer Betreuer] Klemm. "Development of heterogenized catalyst systems for the synthesis of acrylic acid derivatives from carbon dioxide and ethylene / Eko Prasetyo. Betreuer: Elias Klemm." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2015. http://d-nb.info/1074139712/34.
Повний текст джерелаZahouani, Sarah. "Development of new types of mechanocatalytic systems." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE037/document.
Повний текст джерелаThe fascinating process by which mechanical signals are transformed into biochemical reactions in Nature is called mechanotransduction. The goal of my PhD was to mimic Nature by elaborating new types of mechanocatalytic materials, i.e materials able to modulate a catalytic activity when mechanically stimulated. We first aimed at understanding the impact of stretching on the structural properties of polyelectrolyte multilayers films, polymeric matrices often used for the design of smart biomaterials. Within the framework of a new strategy essentially relying on mechanically induced conformational changes, we then developed stretchable polymeric matrices based on poly(ethylene glycol)s. We more particularly designed new types of covalent coatings, called nanogels. We showed that these architectures were buildable on stretchable silicone and that they could be functionalized with different types of biomacromolecules; thus opening new biomimetic routes
Kanjickal, Deenu George. "Perivascular Drug Delivery Systems for the Inhibition of Intimal Hyperplasia." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1133715441.
Повний текст джерелаSimmons, Stephanie. "Influence of processing on the structure and properties of semi-crystalline polymer systems : 1) biodegradable starch/poly(ethylene-vinyl alcohol) blends and 2) polyolefinic thermoplastics." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11379.
Повний текст джерелаWheeler, Nicholas Robert. "Lifetime and Degradation Science of Polymeric Encapsulant in Photovoltaic Systems: Investigating the Role of Ethylene Vinyl Acetate in Photovoltaic Module Performance Loss with Semi-gSEM Analytics." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1473440287427776.
Повний текст джерелаBavarian, Neda. "Investigation of ethylene/propylene and ethylene/propylene/diene polymerization by Cp*TiMe3/B(C6F5)3 catalyst system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/MQ52971.pdf.
Повний текст джерелаMahajan, Vishal Khomdeo. "Study of chalcopyrite oxidation in hydrogen peroxide-ethylene glycol system." abstract and full text PDF (free order & download UNR users only), 2005. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1433392.
Повний текст джерелаIlett, Stephen Mark. "A physico-chemical study of the poly(ethylene oxide) water system." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334498.
Повний текст джерелаPloetz, Christopher Daniel. "Micelles of polybutadiene-b-poly(ethylene oxide) in a binary solvent system." College Park, Md. : University of Maryland, 2008. http://hdl.handle.net/1903/8310.
Повний текст джерелаThesis research directed by: Dept. of Chemical and Biomolecular Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Cantu, Karina Arcaute. "Stereolithography of poly (ethylene glycol) hydrogels with application in tissue engineering as peripheral nerve regeneration scaffolds." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Повний текст джерелаAtilgan, Nurdan. "Design, Synthesis And Electropolymerization Of A New Chemiluminescent Terthienyl System." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609858/index.pdf.
Повний текст джерелаnal Co-Supervisor: Assist. Prof. Dr. Atilla Cihaner September 2008, 57 pages A novel monomer, possessing chemiluminescence properties, 5,7-di-ethylenedioxythiophen-2-yl-2,3-dihydro-thieno[3,4-d]pyridazine-1,4-dione (ETE-Lum) was synthesized. Chemiluminescence properties of ETE-Lum were investigated in alkaline water solution in the presence of H2O2 and this reaction was catalyzed by Fe+3 ion and blood. This study submits a new opportunity to investigate forensic and analytical application instead of 5-amino-2,3-dihydro-1,4-phthalazine-dione (luminol). Response of other metalic cations was also investigated under the same reaction conditions. Electrochemical properties of ETE-Lum were studied in 0.1 M acetonitrile/tetrabutylammonium perchlorate solvent system containing BF3-Et2O and also in neat BF3-Et2O solution. In addition, the corresponding polymer film of ETE-Lum (PETE-Lum) was synthesized successfully via repetitive cycling by cyclic voltammetry and its electrochemical properties were investigated in a monomer-free electrolyte solution. Spectroelectrochemical behavior of the polymer film on indium tin oxide working electrode was also investigated by recording the electronic absorption spectra, in-situ, in monomer-free electrolyte solution at different potentials. Furthermore, spectroelectrochemical studies revealed that PETE-Lum had an electronic band gap of 1.66 eV. The results of electrochemical and electroluminesence measurements indicated that chemiluminecent unit of monomer was protected during polymerization. In addition, PETE-Lum film was found to be electrochemiluminescence active, maintaining its activitiy over 1000 cycles.
CHAPMAN, DONALD RIVERS. "DETERMINING EMPLOYEE EXPOSURE TO ETHYLENE GLYCOL WHILE PERFORMING MAINTENANCE ON AN AIRCRAFT DEICING FLUID COLLECTION SYSTEM." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1187020385.
Повний текст джерелаScheele, Iris. "Hochauflösende Infrarot-Spektroskopie an schwach gebundenen Van-der-Waals-Systemen." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963558668.
Повний текст джерелаHyllestad, Ketil. "Scaling of Calcium Carbonate on a Heated Surface in a Flow Through System with Mono Ethylene Glycol." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemisk prosessteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22335.
Повний текст джерелаFreitas, ValdinÃia Soares. "Polyamines and ethylene metabolisms and antioxidative defense system induction in two maize genotypes contrasting in salinity tolerance." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15060.
Повний текст джерелаPolyamines and ethylene have been cited as important regulators of plant growth and development, and may be involved in plant defense against several abiotic stresses, such as salinity. To withstand with salt harmful effects, plants respond through a coordinated set of physiological and molecular responses to improve their performance under salinity. In order to test the hypothesis that salt tolerance degree in maize genotypes is related to changes in polyamine metabolism associated with ethylene production, two experiments were performed. In the first one, BR5033 (salt-tolerant) and BR5011 (salt-sensitive) maize genotypes were subjected to 80 mM NaCl stress to identify the pattern of ethylene production in leaves and roots. Two peaks of ethylene production at 5.5 h (phase I) and 12.5 h (phase II) after onset the salinity treatment were registered in salt-sensitive leaves; whereas only the first peak of ethylene synthesis was detected in salt-tolerant leaves. Surprisingly, the biphasic ethylene production in roots was much less pronounced than in leaves. In the second experiment, we sought to investigate whether the phases I and II of ethylene production alter the polyamine metabolism in the leaves of maize genotypes. In salt-tolerant genotype, the phase I of ethylene synthesis was associated with signaling events, as evidenced by increased H2O2 levels, which were generated by putrescine (Put) catabolism. An early signaling (at 5.5 h) in the salt-tolerant genotype seemed to be effective to suppress the second peak of ethylene production, known as âstress ethyleneâ. Yet, in the salt-sensitive genotype, the decreased H2O2 concentration during the phase I was associated with a marked increase in ethylene production, which was resulted from upregulation of acid 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) activity and ZmACO5 gene expression. At the phase I, the total polyamine content was increased by salinity in the salt-tolerant, whereas it was decreased in the salt-sensitive one. In the salt-tolerant genotype, the increased total polyamine was sustained by high spermine (Spm) and spermidine (Spd) contents, while the decay in the salt-sensitive genotype was due to the reductions of Put and Spd forms. Otherwise, in the phase II, no significant changes in the total polyamines in salt-tolerant genotype (it was likely due to conversion of Put to Spm/Spd), and decreases in salt-sensitive genotype were registered. Under stress conditions, the salinity-induced improvement of Spd and Spm (free and soluble conjugated forms) in salt-tolerant genotype was bigger than in salt-sensitive one, thus suggesting a key role of polyamines in the maize salt stress acclimation processes. Finally, we investigated if the lack of ethylene production during phase II in salt-tolerant genotype was correlated to improved antioxidant capacity. Salt stress dramatically increased the superoxide levels, the electrolyte leakage and lipid peroxidation, it being more pronounced in both leaves and roots of salt-sensitive genotype. On the other hand, under salinity, salt-tolerant genotype displayed a better performance of enzymatic and non-enzymatic antioxidant system, evidenced by a higher ascorbate and glutathione content and upregulation of superoxide dismutase, ascorbate peroxidase and guaiacol peroxidase activity. In conclusion, our results suggest that the ethylene is intimately involved in salt stress acclimation through activation of intricate signaling pathways mediated by H2O2 that is originated from polyamine catabolism. An efficient signal network raises the polyamine content and antioxidant capacity and is responsible, at least in part, for greater tolerance to salinity of BR5033 maize genotype.
Poliaminas e etileno sÃo reguladores do crescimento e desenvolvimento vegetal, que tambÃm estÃo envolvidos nas respostas de defesa das plantas contra estresses abiÃticos, dentre eles a salinidade. Para lidar com o estresse salino, as plantas realizam ajustes fisiolÃgicos, bioquÃmicos e moleculares, que podem resultar em sua aclimataÃÃo diante dessa condiÃÃo adversa, tornando o indivÃduo mais tolerante ao estresse, em comparaÃÃo Ãqueles que nÃo se encontram aclimatados. Essa pesquisa foi desenvolvida para testar à hipÃtese de que o grau de tolerÃncia à salinidade entre genÃtipos de milho envolve alteraÃÃes no metabolismo das poliaminas associadas à produÃÃo de etileno. Para isso, foram realizados dois experimentos. No primeiro, plantas de milho dos genÃtipos BR5011 (sensÃvel) e BR5033 (tolerante) foram submetidas ao estresse salino (NaCl a 80 mM) para identificar o padrÃo de produÃÃo de etileno em folhas e raÃzes. Nas folhas do genÃtipo sensÃvel, a salinidade intensificou a produÃÃo de etileno apÃs 5,5 h (fase I) e 12,5 h (fase II) apÃs o inÃcio do estresse, enquanto no tolerante isso aconteceu somente com 5,5 h. Nas raÃzes, embora tenha sido observada a produÃÃo bifÃsica de etileno no genÃtipo sensÃvel, esse processo foi muito menos intenso que nas folhas. O segundo experimento teve como objetivo principal investigar se a produÃÃo de etileno pela salinidade nas fases I e II resultava em alteraÃÃes no metabolismo das poliaminas nas folhas dos genÃtipos de milho. No genÃtipo tolerante, a fase I de produÃÃo de etileno foi associada à eventos de sinalizaÃÃo, dado o aumento dos teores de H2O2, mediado pelo catabolismo da putrescina (Put). Essa sinalizaÃÃo pareceu ser eficiente para suprimir a produÃÃo do etileno em condiÃÃes de estresse (fase II ou âetileno do estresseâ) nesse genÃtipo. Jà no sensÃvel, a diminuiÃÃo dos teores de H2O2 na fase I foi acompanhada por um aumento acentuado na produÃÃo do etileno, decorrente de acrÃscimos na atividade da enzima oxidase do Ãcido 1-carboxÃlico-1-aminociclopropano (ACO) e na expressÃo de transcritos do gene ZmACO5 (principal membro expresso). Em geral, a salinidade aumentou os teores de poliaminas totais no genÃtipo tolerante, enquanto reduziu no sensÃvel. Na fase I, na condiÃÃo salina quando comparada com o controle, os teores de poliaminas totais foram aumentados no genÃtipo tolerante enquanto no sensÃvel esses teores foram reduzidos. No genÃtipo tolerante, o aumento nos teores de poliaminas totais foi sustentado principalmente pelo aumento nos teores de espermina (Spm) e espermidina (Spd), enquanto a diminuiÃÃo observada no genÃtipo sensÃvel foi devida, sobretudo, Ãs reduÃÃes nas formas de Put e Spd. Jà na fase II, no genÃtipo tolerante nÃo houve alteraÃÃes nos teores totais de poliaminas (provavelmente, devido a utilizaÃÃo de Put para a sÃntese de Spm e Spd), enquanto no sensÃvel esses teores foram reduzidos. Sob condiÃÃes de salinidade, o aumento nas formas livre e conjugada solÃvel de Spm e Spd foi mais pronunciado no genÃtipo tolerante do que no sensÃvel, sugerindo assim importante papel para essas duas poliaminas nos processos de aclimataÃÃo ao estresse salino em plantas de milho. Por fim, foi investigado se a ausÃncia de produÃÃo do etileno na fase II, causado pela salinidade no genÃtipo tolerante, foi relacionada com uma melhor capacidade antioxidante. O estresse salino aumentou drasticamente os teores do radical superÃxido, o vazamento de eletrÃlitos e a peroxidaÃÃo lipÃdica, sendo isso mais pronunciado nas folhas e raÃzes do genÃtipo sensÃvel. De modo geral, o genÃtipo tolerante teve melhor desempenho do sistema antioxidante enzimÃtico e nÃo enzimÃtico, sob condiÃÃes de estresse salino, evidenciado pelos maiores incrementos nos teores de ascorbato e glutationa e na atividade das enzimas dismutase do superÃxido, peroxidase do ascorbato e peroxidase do guaiacol. Em conclusÃo, os resultados aqui apresentados sugerem que o etileno està intimamente envolvido na aclimataÃÃo ao estresse salino, por meio da ativaÃÃo de vias de sinalizaÃÃo mediadas pelo H2O2 produzido a partir do catabolismo de poliaminas. AlÃm disso, sugere-se que essa sinalizaÃÃo induz o aumento nos teores de poliaminas e melhor capacidade antioxidante no genÃtipo BR5033, sendo isto, pelo menos em parte, responsÃvel por sua maior tolerÃncia ao estresse salino, quando comparado ao BR5011.
Thorpe, Sandra Denise. "Preparation and characterization of sodium poly(aL-glutamate)/poly(pyrrole)/poly(ethylene oxide) polymeric blends for a responsive peptide drug delivery system." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2004. http://digitalcommons.auctr.edu/dissertations/1703.
Повний текст джерелаCanaveze, Yve. "Diferenciação de laticíferos articulados em plantas de Tabernaemontana catharinensis (Apocynaceae)." Botucatu, 2016. http://hdl.handle.net/11449/138104.
Повний текст джерелаResumo: Neste estudo buscamos avaliar diferentes aspectos da diferenciação de laticíferos. O crescimento intrusivo (capacidade de crescer penetrando a lamela média de células adjacentes) e a ação indutora dos laticíferos (capacidade de induzir uma célula vizinha a adquirir características de laticíferos) são mecanismos de crescimento interessantes que podem ocorrer nos laticíferos, mas que são mal compreendidos. O etileno e o ácido jasmônico são hormônios vegetais liberados durante a herbivoria e podem afetar a diferenciação de estruturas secretoras relacionadas à defesa, como laticíferos e ductos resiníferos. Utilizando métodos convencionais em microscopia eletrônica de transmissão, para caracterização da ultraestrutura celular, e imunocitoquímicos, para a detecção de componentes de parede celular, exploramos o desenvolvimento de laticíferos articulados anastomosados com crescimento intrusivo e a ação indutora dos laticíferos no embrião maduro e na planta de Tabernaemontana catharinensis A.DC. (Apocynaceae). Além disso, pulverizamos soluções de etileno 2%, ácido jasmônico 0,1% ou água deionizada em plantas (n = 33) de T. catharinensis cultivadas em condições controladas e avaliamos a influência destes reguladores vegetais sobre a diferenciação dos laticíferos nos tecidos primários e floema secundário. Ultraestruturalmente, verificamos que o processo de incorporação de células ao sistema laticífero é distinto no embrião e na planta. Entretanto, em ambos os casos, o protoplasto da cél... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In this study, we evaluated different aspects of the laticifer differentiation. The intrusive growth (the capacity of grow penetrating the middle lamella that cements adjacent cells) and the inducing action of laticifers (the capacity of induced an adjacent cell to acquirer laticifer features) are exciting growth mechanisms that may occur in laticifers, but they are poorly understood. Ethylene and jasmonic acid are plant hormones released during the herbivory and may affect the differentiation of secretory structures related with plant defense, as laticifers and resin ducts. Using transmission electron microcopy conventional methods (for characterization of the cell ultrastructure), and immunocytochemistry (for detection of the cell wall compounds), we explored the development of the articulated anastomosing laticifers with intrusive growth and the induction action of laticifer in the mature embryo and plant of Tabernaemontana catharinensis A.DC. (Apocynaceae). Additionally, we sprayed solutions of the 2% ethephon, 0.1% jasmonic acid and deonized water in plants of T. catharinensis (n = 33) growing under controlled conditions and evaluated the influence of these plant regulators on laticifer differentiation in the primary tissues and secondary phloem. In the ultrastructure, we verified that the process of cell incorporation within the laticifer system is distinct in the embryo and plant. However, in both the cases the protoplast of the incorporated cells acquires similar feat... (Complete abstract click electronic access below)
Doutor
Eysholdt-Derzsó, Emese [Verfasser], Margret [Akademischer Betreuer] Sauter, and Dietrich [Gutachter] Ober. "Ethylene Response Factor VII transcription factors control the reshaping of the root system architecture in response to hypoxia / Emese Eysholdt-Derzsó ; Gutachter: Dietrich Ober ; Betreuer: Margret Sauter." Kiel : Universitätsbibliothek Kiel, 2018. http://d-nb.info/1236287878/34.
Повний текст джерелаMahagamasekera, Mahagamage Gesha Patalee. "Daylily (Hemerocallis) as a model system for the study of ethylene-insensitive flower senescence : tissue culture and aspects of the development of proteolytic enzyme activities, with special emphasis on leucine aminopeptidase." Thesis, University of Canterbury. Plant and Microbial Sciences, 2000. http://hdl.handle.net/10092/5669.
Повний текст джерелаMyint, Myo. "Production d'antibiotiques par des techniques non conventionnelles de fermentation." Toulouse, INSA, 1989. http://www.theses.fr/1989ISAT0033.
Повний текст джерелаAIDO, LAETITIA. "Optimisation de la fabrication de l'indole-2 carboxylate d'ethyle : automatisation de la reaction de wislicenus et thoma et de la reaction d'hydrogenation de brehm, etude de differents systemes de commande : correlateur logique (...) microprocesseur." Paris 6, 1986. http://www.theses.fr/1986PA066370.
Повний текст джерелаThomas, Joshua Brock. "Lightly crosslinked poly(ethylene glycol)-tethered, pH-responsive biomaterials." Thesis, 2006. http://hdl.handle.net/2152/2940.
Повний текст джерелаChen, Tzu-Ying, and 陳姿穎. "Isothermal Vapor-Liquid Equilibrium for Binary Mixtures of Ethylene Glycol Purification Related Systems." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/p6wqwn.
Повний текст джерела國立臺灣科技大學
化學工程系
103
A static-type apparatus with a liquid-phase circulation loop was used to measure isothermal vapor-liquid equilibrium (VLE) data for the binary systems of solvent A + 1,2-butanediol and solvent A + ethylene glycol at 393.15 K, 423.15 K, and 453.15 K. And also measured the binary systems of solvent B + 1,2-butanediol at 353.15 K, 393.15 K, 433.15 K, and 473.15 K, and solvent B + ethylene glycol at 393.15 K, 433.15 K, and 473.15 K. The experimental results exhibit no azeotropic behavior and positive deviations from Raoult’s law for each binary system. The thermodynamic consistency of the new binary VLE data has been confirmed by the point, area, and infinite dilution tests. The Wilson-HOC, the NRTL-HOC, and the UNIQUAC-HOC models were used to correlate each binary system measured in this work. Each model yielded satisfactory results.
Lin, Chia-Ying, and 林佳穎. "The study of thermal stability and fire retardant systems of ethylene-vinyl acetate copolymer/montmorillonite nanocomposites." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/18297844281976192973.
Повний текст джерела國立雲林科技大學
環境與安全衛生工程系碩士班
99
To achieve the purpose of safety equipment and development of fire retardant and wire cable materials has trended to low smoke and halogen-free flame retardant technology in the business. However, many polymer flame retardant materials required a very high proportion of the metal hydrate filler within the polymer matrix(60 wt%)to achieve a suitable level of flame retardant, which may lead to a lack of flexibility, poor mechanical properties and problems during compounding. In this study, the aluminum hydroxide added montmorillonite(MMT)as the halogen-free flame retardant of EVA, according to the different EVA/ATH/MMT(0, 1, 2, 3 wt%)weight percentage of the preparation of nanocomposite material formulation. And through the XRD test, tensile test, DSC analysis, TGA analysis, LOI test and FE-SEM analysis to explore the addition of organic modified clay(OMMT)and researched the layer-distance, thermal properties, mechanical properties and flame retardant properties. In addition, use XRD to make the characterization analysis, it is found that increasing the polymers into the MMT, layer-distance increased from 1.27 nm to 1.96 nm when used the octadecylamine modified the MMT. For the tensile test, it is found that the montmorillonite weight percentage 3 wt% has the best tensile strength. In addition, the halogen-free flame retardant grade of EVA are added the OMMT in 3 wt%, the composition of nanocomposites was 47 wt% of the ATH filler has the best elongation and fire retardant (LOI was 28). Improvements in tensile and flame retardant properties were observed in nanocomposites.
PIZZI, ELISA. "Synthesis, characterization and functionalization of PEDOT conducting systems on ethylene vinyl alcohol copolymer supports and derivatives." Doctoral thesis, 2014. http://hdl.handle.net/11573/647627.
Повний текст джерелаPIZZI, ELISA. "Synthesis, characterization and functionalization of PEDOT conducting systems on ethylene vinyl alcohol copolymer supports and derivatives." Doctoral thesis, 2014. http://hdl.handle.net/11573/917285.
Повний текст джерелаKavimandan, Nikhil Jayant Peppas Nicholas A. "In vitro and in vivo behavior of insulin delivery systems based on poly(ethylene glycol)-grafted poly(methacrylic acid) hydrogels." 2005. http://repositories.lib.utexas.edu/bitstream/handle/2152/1588/kavimandann71672.pdf.
Повний текст джерелаHuynh, KN. "Extending the shelf life of fresh horticultural produce under industrial settings by modified atmosphere packaging systems." Thesis, 2021. https://eprints.utas.edu.au/39109/1/Huynh_whole_thesis.pdf.
Повний текст джерелаKavimandan, Nikhil Jayant. "In vitro and in vivo behavior of insulin delivery systems based on poly(ethylene glycol)-grafted poly(methacrylic acid) hydrogels." Thesis, 2005. http://hdl.handle.net/2152/1588.
Повний текст джерелаKhan, Isaac John. "The utility of L-tyrosine based polycarbonate copolymers containing poly(ethylene glycol) as a degradable carrier for the release of a hydrophobic peptide molecule." 2009. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.000051844.
Повний текст джерела