Letteratura scientifica selezionata sul tema "Non-natural reactions"
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Articoli di riviste sul tema "Non-natural reactions":
1
SAIGO, Kazuhiko, Atsushi SUDO e Yukihiko HASHIMOTO. "Asymmetric Reactions Using Non-natural Chiral Auxiliaries." Journal of Synthetic Organic Chemistry, Japan 56, n. 5 (1998): 386–94. http://dx.doi.org/10.5059/yukigoseikyokaishi.56.386.
2
Harms, Vanessa, Andreas Kirschning e Jeroen S. Dickschat. "Nature-driven approaches to non-natural terpene analogues". Natural Product Reports 37, n. 8 (2020): 1080–97. http://dx.doi.org/10.1039/c9np00055k.
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Hyster, Todd K. "Radical Biocatalysis: Using Non-Natural Single Electron Transfer Mechanisms to Access New Enzymatic Functions". Synlett 31, n. 03 (7 maggio 2019): 248–54. http://dx.doi.org/10.1055/s-0037-1611818.
Abstract (sommario):
Exploiting non-natural reaction mechanisms within native enzymes is an emerging strategy for expanding the synthetic capabilities of biocatalysts. When coupled with modern protein engineering techniques, this approach holds great promise for biocatalysis to address long-standing selectivity and reactivity challenges in chemical synthesis. Controlling the stereochemical outcome of reactions involving radical intermediates, for instance, could benefit from biocatalytic solutions because these reactions are often difficult to control by using existing small molecule catalysts. General strategies for catalyzing non-natural radical reactions within enzyme active sites are, however, undeveloped. In this account, we highlight three distinct strategies developed in our group that exploit non-natural single electron transfer mechanisms to unveil previously unknown radical biocatalytic functions. These strategies allow common oxidoreductases to be used to address the enduring synthetic challenge of asymmetric hydrogen atom transfer.1 Introduction2 Photoinduced Electron Transfer from NADPH3 Ground State Electron Transfer from Flavin Hydroquinone4 Enzymatic Redox Activation in NADPH-Dependent Oxidoreductases5 Conclusion
4
Hyster, Todd K., e Thomas R. Ward. "Genetic Optimization of Metalloenzymes: Enhancing Enzymes for Non-Natural Reactions". Angewandte Chemie International Edition 55, n. 26 (11 marzo 2016): 7344–57. http://dx.doi.org/10.1002/anie.201508816.
5
Gober, Joshua G., e Eric M. Brustad. "Non-natural carbenoid and nitrenoid insertion reactions catalyzed by heme proteins". Current Opinion in Chemical Biology 35 (dicembre 2016): 124–32. http://dx.doi.org/10.1016/j.cbpa.2016.09.004.
6
Wang, Zhipeng A., Yan-Yu Liang e Ji-Shen Zheng. "Reductive Amination/Alkylation Reactions: The Recent Developments, Progresses, and Applications in Protein Chemical Biology Studies". Current Organic Synthesis 15, n. 6 (29 agosto 2018): 755–61. http://dx.doi.org/10.2174/1570179415666180522093905.
Abstract (sommario):
The chemical modifications of proteins or protein complexes have been a challenging but fruitful task in the post-genomic era. Bioorthogonal reactions play an important role for the purpose of selective functionalization, localization, and labeling of proteins with natural or non-natural structures. Among these reactions, reductive amination stands out as one of the typical bioorthogonal reactions with high efficiency, good biocompatibility, and versatile applications. However, not many specific reviews exist to discuss the mechanism, kinetics, and their applications in a detailed manner. In this manuscript, we aim to summarize some current developments and mechanistic studies of reductive amination reaction and its applications. We hope reductive amination reaction can contribute to a wider scope of protein chemistry research en route in the chemical biology frontier as one of the well-known bioorthogonal reactions.
7
Taylor, James S., e Yung-Hian Leow. "Cutaneous Reactions to Rubber". Rubber Chemistry and Technology 73, n. 3 (1 luglio 2000): 427–85. http://dx.doi.org/10.5254/1.3547600.
Abstract (sommario):
Abstract The three major adverse cutaneous reactions to rubber include natural rubber latex allergy, irritant contact dermatitis and allergic contact dermatitis. An overview of relevant aspects of the types of natural and synthetic rubber, rubber production, and specific chemicals used in compounding and vulcanization, as well as latex proteins is essential to an understanding of these reactions. Natural rubber latex allergy is a type I, IgE mediated, immediate hypersensitivity reaction to one or more proteins present in natural rubber latex with clinical manifestations ranging from contact urticaria to allergic rhinitis, asthma, and anaphylaxis. Over the past decade, natural rubber latex allergy has become a major medical, occupational health, and medicolegal problem. Individuals at highest risk are patients with spina bifida and health care workers. Diagnosis is based largely on clinical history and examination, and serologic and intracutaneous testing. Irritant contact dermatitis is non-immunologic and is the most common cutaneous reaction to rubber. Cumulative exposure to low-grade irritants impairs the barrier function of the skin and allows penetration of potential irritants and allergens. Diagnosis is based on history of exposure to known irritants, cutaneous examination, and exclusion of allergy. Allergic contact dermatitis is a type IV cell mediated, delayed hypersensitivity reaction which occurs primarily from exposure to rubber chemicals either directly or from residual amounts present in rubber products. Most cases present with an eczematous dermatitis, but purpura, lichenoid dermatitis, and depigmentation occasionally occur. Diagnosis is made on the basis of history, examination, and epicutaneous patch testing with rubber chemicals and rubber products. Treatment is with allergen and irritant avoidance and substitution, environmental control, personal protective equipment and topical and systemic pharmacologic therapy. A unified approach is needed in the diagnosis and treatment of adverse cutaneous reactions to rubber and it is important to remember that some patients may have both contact dermatitis and natural latex allergy. Determining the bioavailability and elicitation threshold of rubber allergens may be helpful in reducing allergic reactions from consumer and industrial rubber products.
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Xu, Guangcai, Michele Crotti, Thangavelu Saravanan, Kim M. Kataja e Gerrit J. Poelarends. "Enantiocomplementary Epoxidation Reactions Catalyzed by an Engineered Cofactor‐Independent Non‐natural Peroxygenase". Angewandte Chemie 132, n. 26 (14 aprile 2020): 10460–64. http://dx.doi.org/10.1002/ange.202001373.
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Xu, Guangcai, Michele Crotti, Thangavelu Saravanan, Kim M. Kataja e Gerrit J. Poelarends. "Enantiocomplementary Epoxidation Reactions Catalyzed by an Engineered Cofactor‐Independent Non‐natural Peroxygenase". Angewandte Chemie International Edition 59, n. 26 (14 aprile 2020): 10374–78. http://dx.doi.org/10.1002/anie.202001373.
10
Fu, Peng, e John B. MacMillan. "Carpatizine, a novel bridged oxazine derivative generated by non-enzymatic reactions". Organic & Biomolecular Chemistry 15, n. 25 (2017): 5275–78. http://dx.doi.org/10.1039/c7ob01178d.
Tesi sul tema "Non-natural reactions":
1
Lee, Albert. "Synthesis of polyurethane from one hundred percent sustainable natural materials through non-isocyanate reactions". Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53038.
Abstract (sommario):
The synthesis route for the preparation of polyurethane using 100% sustainable materials was proposed. Lignin, one of the most abundance biomass on Earth, was used as one raw material, while the other one used is soybean oil. The reaction occurs in 3 steps, and is done in 2 different pot reactions. Briefly, purchased epoxidized soybean oil is carbonated to synthesize carbonated soybean oil. Then carbonated soybean oil was reacted with coupling agent, 3-aminopropyltriethoxysilane to produce urethane monomers. Finally, prepared urethane monomers were polymerized with lignin to produce sustainable polyurethane. Molecular structures were intensively analyzed using Fourier-Transform Infrared Spectroscopy and Nuclear Magnetic Resonance Spectroscopy. In addition, mechanical properties of prepared polyurethane were analyzed in order to evaluate its performance and compare with the polyurethanes available commercially. Our results indicated that the highest tensile strength achieved was 1.4 MPa, which is slightly below the typical tensile strengths of processible polyurethane. Chemical properties of all the intermediates and products and implications for future research are discussed.
2
ZAMBERLAN, Francesco. "Synthesis and biological applications of non natural α-amino acids". Doctoral thesis, Università degli studi di Ferrara, 2013. http://hdl.handle.net/11392/2388868.
Abstract (sommario):
In this PhD Thesis work, the synthesis and the biomedical application of non natural
a-amino acids was accomplished in three different projects.
A “one-pot” procedure for the synthesis of optically active and pure methyl
N-acetamido acrylate starting from cheap and commercial sources was developed
and fine-tuned, obtaining the target compound in good yields and identifying the
major reaction by product. This acrylate was used as acceptor in Michael reaction
conditions for the formation of new C-C and C-S bonds, evaluating the asymmetry
induced by the (-)-menthol.Different nucleophiles were used and different bases
were tested in order to obtain a full conversion. After that, reaction of the aforementioned
molecule with opportune nucleophiles to synthesise five-membered tetrahydrothiophene
rings and other intermediates with a bicyclo[3.1.0]hexane and bicyclo[
4.1.0]heptane structure was investigated. The project was undertaken in order
to find new synthetic ways obtain constrained glutamate analogues, which have
been identified by Eli Lilly as potent, selective and active agonists of mGluR receptors.
The second project, developed in the laboratory of Professor Matteo Zanda at
the Univesity of Aberdeen, is focused on the synthesis of small arginine-containing
peptides and arginine analogues. The small peptides are obtained by simple coupling
of the amino acid residue with different picolyl amines, while analogues of
the parent amino acid will contain a triple bond and a methyl or trifluoromethyl
substituent on the a-carbon of the amino acid skeleton. Interest in these two type
of compounds was risen because arginine is a substrate for Nitric Oxide Synthase,
a class of enzymes involved in the regulation of muscular relax and blood pressure
through nitric oxide synthesis starting from the aforementioned amino acid. The
designed and synthesised substrates result being able to polarise their signal under
specific NMR conditions in the presence of parahydrogen. In this way, a possibility
towards the synthesis of of specific and target-focused tracers for Magnetic Resonance
Imaging would be achieved, allowing for a simple and secure detection of
illness via a simple and quick MRI scan. Indeed, some of the synthesised compounds
polarise and are substrates for the Enzyme. On the last note, a method for
the determination of the amount of trifluoroacetic counter-ion was developed.
The third project is focused on the development of an alternative synthetic route
for the cheap synthesis of 2,6-dimethyl-L-tyrosine, a potent amino acid analogue to
tyrosine and employed in peptides which target opioid receptors. An analogue of
Hagemann’s ester ’s was used as starting point for the entire process and it was
used in two synthetic pathways. The first one is stereoselective in the fact that
involves alkylation of the chiral synthon 2,5-diketopiperazine, while in the second
one the key-step involves a Michael addition for the introduction of the amino
acidic residue.
3
Stafford, Petra M. "Approaches to the synthesis of non-natural carbohydrates via silicon tethered ene and allyl transfer reactions". Thesis, University of Oxford, 2004. http://ora.ox.ac.uk/objects/uuid:b1ea3f8b-6a69-443d-8171-0ffd1cc37b45.
Abstract (sommario):
The efficiency of an intermolecular synthetic transformation can be improved by temporarily linking reaction components together. The addition of a tether leads to enhanced regio- and stereocontrol by restraining the mobility of the reacting partners, effectively transforming an intermolecular reaction into its intramolecular counterpart. Silicon tethers are associated with an expanding range of applications, including hydrosilylations, cycloadditions and radical reactions. This project has continued work pioneered by the Robertson group into silicon tethered Type I ene cyclisations, extending the methodology to incorporate O-linked ene precursors with the intention of applying this chemistry to the stereoselective synthesis of non-natural carbohydrates. This investigation encompassed advances in the area made concurrently within the Robertson group and extended the scope of the ene protocol by successfully incorporating latent functionality into the R-group side chain. In addition, a new route to the O-linked ene precursors was established employing silylcyanohydrin chemistry. In general, the ene reactions proceeded stereoselectively to generate the expected oxasilacyclohexanols, which could be cleaved oxidatively to afford 1,2,4-triols. The formation of the major diastereomer was consistent with ene cyclisation proceeding through a trans-decalin type transition state (e.g. leading to compound 1). During our attempts to effect ene cyclisation in the O-linked prenyl systems we observed an unexpected side reaction, resulting from intramolecular allylic transfer. Further studies revealed that this novel process could be initiated thermally to generate 1,2-homoallylic diols with excellent levels of stereoselectivity. Tethered E- and Z-crotylsilanes were found to be equally receptive to this process. Although attempts to apply the silicon tethered allyl transfer chemistry to aldimines and glycosides failed, an extension of the methodology to incorporate cyclohexadienylsilanes was successful and provided interesting synthetic intermediates for elaboration to carbasugars.
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Larsen, Catharine Hoang-Mai MacMillan David W. C. Barton Jacqueline K. "Investigating imidazolidinone catalysts : enantioselective organocatalytic Diels-Alder reactions, conjugate additions to access non-natural alpha-amino acids, and bimodal catalyst activation for the development of organo-cascade reactions /". Diss., Pasadena, Calif. : California Institute of Technology, 2006. http://resolver.caltech.edu/CaltechETD:etd-10142005-105810.
5
Pujol, Manon. "Ingénierie de métalloenzymes pour la catalyse abiologique". Electronic Thesis or Diss., Aix-Marseille, 2023. http://theses.univ-amu.fr.lama.univ-amu.fr/230310_PUJOL_718skm30lico606bv439mbsvs_TH.pdf.
Abstract (sommario):
Dans un contexte de développement durable, l’industrie se tourne vers des procédés qui respectent les principes de la chimie verte (ex: remplacement des catalyseurs chimiques par des enzymes). Cependant, beaucoup de réactions industrielles n’existent pas dans la nature et plusieurs protéines héminiques ont alors été modifiées pour les catalyser. A côté, seules quelques enzymes non héminiques dépendantes du fer et une protéine à cobalt ont été décrites pour les transferts de carbènes et nitrènes alors que d'autres métaux les catalysent. Nous avons cherché à réorienter l'activité d'une classe de métalloenzymes à cuivre, les lytic polysaccharide monooxygenases (LPMOs), afin de développer des biocatalyseurs les réactivités abiologiques. Pour cela, la sphère de coordination du cuivre de la LPMO SmAA10 a été modulée par mutagenèse pour créer de nouveaux motifs de coordination. Les mutants ont été caractérisés puis évalués sur leur capacité à catalyser des réactions non-naturelles. De bonnes activités ont été obtenues pour certaines transformations (ex : réarrangement de Doyle-Kirmse). Ces activités étant similaires à celle du cuivre en solution, nous nous sommes demandé si les réactions étaient catalysées au site actif des enzymes. En nous concentrant sur le réarrangement de Doyle-Kirmse, nous avons montré que la LPMO ne perdait pas de manière significative son cuivre. En revanche, nous mettons en évidence l’addition d’un carbène sur un résidu du site actif d'un mutant, entraînant la libération du cuivre. Nous avons ensuite étendu la gamme des réactions non naturelles catalysées par les hémoprotéines en réalisant un réarrangement de Sommelet-Hauser avec une myoglobine évoluéeIn the context of sustainable development, chemical industries turn progressively towards processes respecting the criteria of green chemistry, via for example the replacement of chemical catalysts by enzymes. However, lots of industrial reactions do not exist in nature. To over come this limitation, several hemoproteins have been engineered to catalyze abiological reactions. Besides, only few non-heme iron-dependent enzymes and one cobalt protein were also reported for carbene and nitrene transfers whereas other metals catalyze them. We first aimed to repurpose the activity of a class of copper metalloenzymes, the lytic polysaccharide monooxygenases (LPMOs), to develop new biocatalysts for new-to-nature reactivities. To repurpose the LPMO activity, the copper coordination sphere within the SmAA10 LPMO was modulated by site directed mutagenesis to create new metal coordination motifs. The mutants were characterized and were then assessed for their capacity to catalyze non-natural reactions. Good activities were obtained for some abiological transformations (i.e. : the Doyle-Kirmse rearrangement). These activities being similar to that of copper in solution, we wondered if the reactions were really catalyzed at the enzyme active site. Focusing on the Doyle-Kirmse rearrangement, we found no evidence that the wild-type LPMO significantly loses some copper. In contrast, we high light the carbene addition to an active site residue to a specific LPMO mutant, resulting in its copper release. Next, we extended the non-natural reactions range catalyzed by hemoproteins by performing for a Sommelet-Hauser rearrangement with an evolved myoglobin
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Bull, Joseph. "The application of hydrolytic enzymes for biotransformations of natural products in non-aqueous reaction conditions". Thesis, University of Exeter, 2009. http://hdl.handle.net/10036/76873.
Abstract (sommario):
Flavonoids are naturally occurring compounds that are consumed regularly in the diet. The property of flavonoids, which they are most commonly known for, is their antioxidant activity. Other potential pharmaceutical applications of flavonoids can be related to their enzyme inhibition, anti-allergic, anti-inflammatory, anti-microbial and anti-cancer properties. Lipases have been used effectively in the production of flavonoid ester derivatives that have shown both increased antioxidant and antimicrobial activity. Enzymatic esterifications of flavonoids are performed in organic solvents that increase substrate solubility of complex organic molecules. For the esterification of compounds in non-aqueous reaction conditions, vinyl esters are often preferred as substrates compared to carboxylic acids (which can be involved in reversible reactions, due to the formation of the by-product, water). In this study a group of vinyl esters of tert-butoxycarbonylated amino acid derivatives were synthesized to study alongside a range of commercially available vinyl esters. The synthesis of ester derivatives of naringin using a range of hydrolytic enzymes has been studied. A range of small to medium sized commercially available vinyl esters (C2- C10), as well as amino acid vinyl esters were selected for the biotransformations. For the esterification of naringin, small-scale reactions were carried out for 72 hrs and the reaction mixtures were analysed by HPLC. Lipases from the species Pseudomonas stutzeri, Candida antarctica and Alcaligenes spp. performed more than 80% conversion of naringin with some of the selected acylating agents. Reactions carried out with P. stutzeri lipase were scaled up to isolate the product of the biotransformation. None of the screened enzymes were successful in the acylation of naringin with the amino acid vinyl esters. Assays were carried out to compare the antioxidant activity of naringin and the synthesized derivatives. Two of the acyl derivatives showed a greater antioxidant activity in the reduction of Cu2+, compared to naringin. Aminoglycosides are antibiotics that have anti-bacterial properties. As well as their anti-bacterial properties some have been employed for their ability to suppress stop codons, which is a useful property in reducing symptoms of some hereditary disorders. In the present work attempts were made to derivatise an aminoglycoside by acylating it with the amino acid vinyl esters, using hydrolytic enzymes. Despite screening with various proteases in different solvents, the acylation of amikacin was not succesful during this investigation.
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ILLUMINATI, Davide. "Exploring the potential of Pd-catalyzed C-H activation reaction for the synthesis of non-natural amino acid 2,6-dimethyl tyrosine-like (Dmt-like) analogues". Doctoral thesis, Università degli studi di Ferrara, 2022. http://hdl.handle.net/11392/2478825.
Abstract (sommario):
Il sistema oppioide è coinvolto in molteplici funzioni biologiche, tra queste la principale è la modulazione del dolore.
Il sistema oppioide si compone di quattro diverse famiglie di recettori: MOP, KOP, DOP e NOP. Tutti i recettori oppioidi appartengono alla famiglia delle proteine G accoppiate a recettore, Gi/G0.
I ligandi endogeni dei recettori sono i peptidi oppioidi endogeni, che legatisi ai recettori, inducono iperpolarizzazione cellulare e apertura di canali ionici, e regolando il rilascio di secondi messaggeri, promuovono cascate di segnalazione volte allo spegnimento del firing cellulare.
L’attivazione dei recettori MOP comporta l’espressione del maggiore effetto analgesico, associato però all’insorgenza di una serie di effetti collaterali, tra i quali costipazione, tosse, depressione respiratoria, dipendenza e tolleranza, che ne limitano l’uso in ambito clinico. Sebbene l’attivazione del solo recettore MOP sia accompagnata dal manifestarsi dei suddetti effetti collaterali, la co-attivazione di diversi recettori tende a ridimensionare l’insorgenza degli effetti indesiderati. In particolare, l’attivazione dei recettori MOP/NOP sembra rappresentare al meglio tale profilo terapeutico. Ligandi bivalenti, a target MOP/NOP sono stati ottenuti modificando il peptide endogeno Nocicettina (N/OFQ), effettuando delle sostituzioni nella porzione N-terminale.
La modifica più significativa, è rappresentata dalla sostituzione del residuo Phe1 con il derivato amminoacidico non-naturale 2,6-dimetil tirosina (Dmt). Alcuni peptidi aventi il residuo Dmt incorporato in struttura, mostrano maggiore attività biologica, tempo di emivita, e particolari caratteristiche di affinità e selettività recettoriali rispetto ai peptidi di riferimento.
Questo lavoro di tesi, si propone di sviluppare diverse strategie di sintesi per ottenere derivati amminoacidici Dmt-like. In particolare, tramite reazioni di C(sp2)-H attivazione Pd-catalizzate, è stato possibile ottenere lo scaffold Dmt-like desiderato, funzionalizzando successivamente la posizione 4 dell’anello aromatico. Alcuni di questi analoghi sono stati inseriti con successo nel message domain di N/OFQ(1-13)-NH2, tramite sintesi peptidica in fase solida (SPPS).
Una simile strategia sintetica ha permesso di ottenere il derivato noto come monometil-tirosina (Mmt), partendo dalla 3-nitro-L-tirosina, tramite controllo regio-selettivo della reazione di C(sp2)-H attivazione Pd-catalizzata.
Inoltre, per reazioni di C(sp3)-H attivazione Pd-catalizzate, è stato possibile arilare L-Ala in posizione beta, ottenendo 3,5-Dmt (isomero costituzionale di Dmt) e i derivati di bis-arilazione di Tyr e di 3,5-Dmt.
In questo lavoro di tesi è riportato anche l’ottenimento di un ligando bivalente MOP/NOP eterotetramerizzato. La sintesi di peptidi tetramerizzati si propone come strategia innovativa per migliorare il profilo farmacocinetico dei peptidi ad uso terapeutico, aumentandone il tempo di emivita. Viene qui riportata la sintesi del derivato eterotetramerizzato H-PWT1- N/OFQ-[Dmt1]dermorfina selettivo per i recettori NOP e MOP, in grado di espletare un simile profilo agonista, rispetto ai peptidi di riferimento.
Questa strategia sintetica si è dimostrata versatile e potenzialmente applicabile a qualsiasi sequenza peptidica, volta all’ottenimento di profili farmacologici eterotetramerizzati bivalenti.
Con l’obiettivo di identificare nuovi profili peptidici con attività agonista, a target misto MOP/NOP, è stata utilizzato il residuo non-naturale Dmt, Fmoc-protetto, per sintetizzare una serie di peptidi di sequenza generica [Tyr/Dmt1,Xaa5]N/OFQ(1-13)-NH2. Il miglior risultato, in termini di potenza, espressa per entrambi i recettori, si è dimostrato essere il derivato caratterizzato dalla sostituzione con Dmt in ambedue i residui Tyr1 e Thr5, [Dmt1,5]N/OFQ(1-13)-NH2, ad oggi agonista, a target MOP/NOP, con maggiore attività biologica, in letteratura.The opioid system is involved in the modulation of multiple biological functions, above all pain behavior. It consists of four different families of opioid receptors known as MOP, KOP, DOP and NOP. All of these are Gi/G0 protein coupled receptors expressed throughout the spinal axis and pain related pathways. The activation of these receptors induces cell hyperpolarization and ion channels opening, regulating the release of second messengers and promoting signaling cascades which converge to cell desensitization, analgesia. The most potent analgesic effect is known to be exerted by the activation of MOP receptor, unfortunately it is associated to important side effects which represent the major limitation for their clinical use, such as constipation, cough, itch, respiratory depression, tolerance and addiction. While the co-activation of different receptor subtypes is emerging as a safer therapeutic strategy to promote analgesia. The simultaneous activation of MOP and NOP receptors has been suggested as an interesting pharmacological approach to treat pain with potentially reduced side effects. Dual MOP/NOP ligands have been obtained through subtle changes of the N-terminal part of Nociceptin/Orphanin FQ (N/OFQ). The most important substitution which confers such interesting behavior is the replacement of the phenylalanine residue at the N-terminal position (Phe1) of N/OFQ with the non-canonical amino acid 2,6-dimethyl tyrosine (Dmt). Of note, some Dmt-modified opioid peptides exhibited increased biological activity and extended half-life with unexpected affinity and selectivity patterns. This thesis has been focused on the development of different synthetic strategies for the synthesis of Dmt-like analogues. In particular, we were able to functionalize the 4-position of the phenyl ring of the target residues after an ortho-ortho C(sp2)-H alkylation reaction. Some of these analogues were successfully employed as building blocks in solid phase peptide synthesis (SPPS) for the synthesis of N/OFQ(1-13)-NH2 derivatives modified at the message domain. Moreover, Pd-catalyzed C(sp2)-H activation was successfully applied for the synthesis of the non-natural amino acid mono methyl tyrosine (Mmt) in which 3-nitro-L-tyrosine was employed as starting material. Another Pd-catalyzed synthesis here described is focused on a beta C(sp3)-H activation of a properly functionalized alanine precursor which led to the obtainment of 3,5-Dmt, as well as bis-arylated analogues of Tyr and 3,5-Dmt. This thesis work includes a strategy for assembling bifunctional (NOP/MOP) heterotetrabranched ligands. Peptide clustering is emerging as an innovative tool to enhance the pharmacokinetic profile of therapeutic peptides, particularly by increasing their half-life. Specifically, we synthesized the heteromultimeric peptide conjugate H-PWT1-N/OFQ-[Dmt1]dermorphin (Scheme 4) to target NOP and MOP opioid receptors, observing similar and high agonist potency compared to the parent peptides. The synthetic approach is extremely versatile and virtually applicable to different peptide sequences whose pharmacological activity could be combined to generate dual acting multimeric compounds. Finally, with the aim to identify novel mixed NOP/opioid receptor peptide agonists, Dmt was employed as Fmoc-precursor in SPPS to build a series of linear peptides with the general sequence [Tyr/Dmt1,Xaa5]N/OFQ(1-13)-NH2. The best results in terms of NOP versus MOP opioid receptor potency were obtained by substituting both Tyr1 and Thr5 at the N-terminal portion of N/OFQ(1-13)-NH2 with Dmt. [Dmt1,5]N/OFQ(1-13)-NH2 has been identified as the most potent dual NOP/MOP receptor peptide agonist so far described in literature.
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Mould, Katy M. "Studies towards the total synthesis and structure elucidation of leiodolide A". Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/4113.
Abstract (sommario):
Leiodolide A is a unique natural product isolated from Pacific marine sponges which has provided an interesting target for total synthesis due to its complex structure and undefined stereochemistry. Although synthetic work towards the synthesis of sister compound leiodolide B has been published, the total synthesis of leiodolide A is yet to be achieved but remains an important target due to high potency against leukaemia, non-small lung and ovarian cancers. The convergent strategy towards the synthesis of leiodolide A involved the synthesis of three subunits; a synthetic route to the C21-C25 vinyl stannane is described, and efforts towards the synthesis of the bidirectional C11-C20 subunit are detailed. Asymmetric vinylogous aldol methodology was developed for the installation of the 1,2-syn propionate motif found in the C1-C10 subunit and in other polypropionate natural products, and was shown to be applicable to a range of substrates in moderate diastereoselectivity and excellent enantioselectivity.
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Mohammad, Shabbair. "Vers la synthèse totale du FR225654 inhibiteur de la gluconéogenèse". Phd thesis, Université René Descartes - Paris V, 2013. http://tel.archives-ouvertes.fr/tel-00932775.
Abstract (sommario):
Le diabète de type 2 est aujourd'hui une maladie de plus en plus répandu. En ce sens il est nécessaire de mettre au point de nouveau composé permettant d'inhiber la gluconéogenèse. C'est pourquoi nous nous sommes intéressé à la synthèse du FR225654 1, décaline présentant une activité hypoglycémiante in vivo après administration par voie orale et inhibiteur de la néoglucogenèse in vitro (IC50 = 1,1.10-7 M). Ce composé, isolé en 2005 du champignon Phoma sp N°00144 et jamais encore synthétisé à ce jour, possède un mécanisme d'action inconnu. La nécessité d'une synthèse par voie chimique convergente et flexible, permettant l'accès à des analogues, est donc évidente. La stratégie consistait à préparer une trans-décaline par le biais d'une réaction de Diels-Alder intramoléculaire à partir d'un triène précurseur. La combinaison de ces travaux a constitué une avancée importante dans le cadre de la synthèse du FR225654, un hypoglycémiant potentiel. La mise au point d'une synthèse convergente du précurseur de la réaction de Diels-Alder permettra notamment d'effectuer par la suite des modifications aisées en vue de la préparation d'une vaste gamme d'analogues simplifiés. A ce jour, le produit de cyclo-addition a été isolé et caractérisé, validant ainsi l'étape clé de la stratégie de synthèse. Ainsi, l'accès rapide au FR225654 est rendu possible et la synthèse d'analogues est maintenant envisageable. Les produits synthétisés feront l'objet d'une évaluation biologique, l'objectif ultime étant d'accéder à de nouveaux médicaments pour le traitement du diabète de type 2.
10
Larsen, Catharine Hoàng-Mai. "Investigating Imidazolidinone Catalysts: Enantioselective Organocatalytic Diels-Alder Reactions, Conjugate Additions to Access Non-Natural ∝-Amino Acids, and Bimodal Catalyst Activation for the Development of Organo-Cascade Reactions". Thesis, 2006. https://thesis.library.caltech.edu/5254/1/THallpages.pdf.
Abstract (sommario):
The MacMillan group focuses on the development of new strategies that harness the power of simple organic compounds to catalyze asymmetric reactions. To this end, we have designed amine catalysts which activate alpha,beta-unsaturated aldehydes via the reversible formation of chiral iminium ions (in analogy to LUMO-lowering activation by reversible metal-substrate complexation). Kinetic studies highlight the importance of the acid co-catalyst and identified a more reactive imidazolidinone catalyst complex, which improved enantioselectivities and vastly expanded the substrate scope of the first highly enantioselective organocatalytic Diels–Alder reaction. Exploration of the crucial components of catalyst architecture led to the development of the second-generation imidazolidinone that not only catalyzes cycloadditions, but a variety of other reactions of aldehydes with excellent selectivity.
Complementary to the 1,2-addition observed with Lewis acids, the alternative mode of activation offered by iminium catalysis allows for 1,4-addition of heterocycles to alpha,beta-unsaturated aldehydes. Using a chiral amine catalyst, the first asymmetric conjugate addition of oxazoles generates protected quaternary alpha-amino acids with an adjacent tertiary stereocenter, a widely applicable motif in biology, materials science, and medicine. Finally, having demonstrated that imidazolidinones can activate both electrophiles (LUMO-lowering) and nucleophiles (HOMO-raising), these iminium and enamine catalysis cycles can be linked for tandem nucleophilic addition/electrophilic trapping of enals. In a single synthetic operation, this enantioselective conjugate addition/alpha-halogenation sequence takes achiral starting materials and selectively connects them, creating multiple stereocenters across the newly formed bonds.
Libri sul tema "Non-natural reactions":
1
Garshin, Anatoliy. General and inorganic chemistry in diagrams, figures, tables, and chemical reactions. ru: INFRA-M Academic Publishing LLC., 2020. http://dx.doi.org/10.12737/1070937.
Abstract (sommario):
The textbook in the form of definitions, drawings, diagrams, tables, formulas and chemical reactions outlines the main provisions of General and inorganic chemistry.
It is intended for students of non-chemical specialties of higher education institutions. It can be used by students of secondary vocational schools of chemical and medical-biological profiles, secondary school teachers, applicants, foreign students studying in Russian technical universities and natural science faculties of universities, as well as in the system of pre-University training of foreign students. Each Chapter of the manual contains questions for self-control of the knowledge received by the student and checking the depth of assimilation of the studied material.
2
Ufimtseva, Nataliya V., Iosif A. Sternin e Elena Yu Myagkova. Russian psycholinguistics: results and prospects (1966–2021): a research monograph. Institute of Linguistics, Russian Academy of Sciences, 2021. http://dx.doi.org/10.30982/978-5-6045633-7-3.
Abstract (sommario):
The monograph reflects the problems of Russian psycholinguistics from the moment of its inception in Russia to the present day and presents its main directions that are currently developing. In addition, theoretical developments and practical results obtained in the framework of different directions and research centers are described in a concise form. The task of the book is to reflect, as far as it is possible in one edition, firstly, the history of the formation of Russian psycholinguistics; secondly, its methodology and developed methods; thirdly, the results obtained in different research centers and directions in different regions of Russia; fourthly, to outline the main directions of the further development of Russian psycholinguistics. There is no doubt that in the theoretical, methodological and applied aspects, the main problems and the results of their development by Russian psycholinguistics have no analogues in world linguistics and psycholinguistics, or are represented by completely original concepts and methods. We have tried to show this uniqueness of the problematics and the methodological equipment of Russian psycholinguistics in this book. The main role in the formation of Russian psycholinguistics was played by the Moscow psycholinguistic school of A.A. Leontyev. It still defines the main directions of Russian psycholinguistics. Russian psycholinguistics (the theory of speech activity - TSA) is based on the achievements of Russian psychology: a cultural-historical approach to the analysis of mental phenomena L.S. Vygotsky and the system-activity approach of A.N. Leontyev. Moscow is the most "psycholinguistic region" of Russia - INL RAS, Moscow State University, Moscow State Linguistic University, RUDN, Moscow State Pedagogical University, Moscow State Pedagogical University, Sechenov University, Moscow State University and other Moscow universities. Saint Petersburg psycholinguists have significant achievements, especially in the study of neurolinguistic problems, ontolinguistics. The most important feature of Russian psycholinguistics is the widespread development of psycholinguistics in the regions, the emergence of recognized psycholinguistic research centers - St. Petersburg, Tver, Saratov, Perm, Ufa, Omsk, Novosibirsk, Voronezh, Yekaterinburg, Kursk, Chelyabinsk; psycholinguistics is represented in Cherepovets, Ivanovo, Volgograd, Vyatka, Kaluga, Krasnoyarsk, Irkutsk, Vladivostok, Abakan, Maikop, Barnaul, Ulan-Ude, Yakutsk, Syktyvkar, Armavir and other cities; in Belarus - Minsk, in Ukraine - Lvov, Chernivtsi, Kharkov, in the DPR - Donetsk, in Kazakhstan - Alma-Ata, Chimkent. Our researchers work in Bulgaria, Hungary, Vietnam, China, France, Switzerland. There are Russian psycholinguists in Canada, USA, Israel, Austria and a number of other countries. All scientists from these regions and countries have contributed to the development of Russian psycholinguistics, to the development of psycholinguistic theory and methods of psycholinguistic research. Their participation has not been forgotten. We tried to present the main Russian psycholinguists in the Appendix - in the sections "Scientometrics", "Monographs and Manuals" and "Dissertations", even if there is no information about them in the Electronic Library and RSCI. The principles of including scientists in the scientometric list are presented in the Appendix. Our analysis of the content of the resulting monograph on psycholinguistic research in Russia allows us to draw preliminary conclusions about some of the distinctive features of Russian psycholinguistics: 1. cultural-historical approach to the analysis of mental phenomena of L.S.Vygotsky and the system-activity approach of A.N. Leontiev as methodological basis of Russian psycholinguistics; 2. theoretical nature of psycholinguistic research as a characteristic feature of Russian psycholinguistics. Our psycholinguistics has always built a general theory of the generation and perception of speech, mental vocabulary, linked specific research with the problems of ontogenesis, the relationship between language and thinking; 3. psycholinguistic studies of speech communication as an important subject of psycholinguistics; 4. attention to the psycholinguistic analysis of the text and the development of methods for such analysis; 5. active research into the ontogenesis of linguistic ability; 6. investigation of linguistic consciousness as one of the important subjects of psycholinguistics; 7. understanding the need to create associative dictionaries of different types as the most important practical task of psycholinguistics; 8. widespread use of psycholinguistic methods for applied purposes, active development of applied psycholinguistics. The review of the main directions of development of Russian psycholinguistics, carried out in this monograph, clearly shows that the direction associated with the study of linguistic consciousness is currently being most intensively developed in modern Russian psycholinguistics. As the practice of many years of psycholinguistic research in our country shows, the subject of study of psycholinguists is precisely linguistic consciousness - this is a part of human consciousness that is responsible for generating, understanding speech and keeping language in consciousness. Associative experiments are the core of most psycholinguistic techniques and are important both theoretically and practically. The following main areas of practical application of the results of associative experiments can be outlined. 1. Education. Associative experiments are the basis for constructing Mind Maps, one of the most promising tools for systematizing knowledge, assessing the quality, volume and nature of declarative knowledge (and using special techniques and skills). Methods based on smart maps are already widely used in teaching foreign languages, fast and deep immersion in various subject areas. 2. Information search, search optimization. The results of associative experiments can significantly improve the quality of information retrieval, its efficiency, as well as adaptability for a specific person (social group). When promoting sites (promoting them in search results), an associative experiment allows you to increase and improve the quality of the audience reached. 3. Translation studies, translation automation. An associative experiment can significantly improve the quality of translation, take into account intercultural and other social characteristics of native speakers. 4. Computational linguistics and automatic word processing. The results of associative experiments make it possible to reveal the features of a person's linguistic consciousness and contribute to the development of automatic text processing systems in a wide range of applications of natural language interfaces of computer programs and robotic solutions. 5. Advertising. The use of data on associations for specific words, slogans and texts allows you to predict and improve advertising texts. 6. Social relationships. The analysis of texts using the data of associative experiments makes it possible to assess the tonality of messages (negative / positive moods, aggression and other characteristics) based on user comments on the Internet and social networks, in the press in various projections (by individuals, events, organizations, etc.) from various social angles, to diagnose the formation of extremist ideas. 7. Content control and protection of personal data. Associative experiments improve the quality of content detection and filtering by identifying associative fields in areas subject to age restrictions, personal information, tobacco and alcohol advertising, incitement to ethnic hatred, etc. 8. Gender and individual differences. The data of associative experiments can be used to compare the reactions (and, in general, other features of thinking) between men and women, different social and age groups, representatives of different regions. The directions for the further development of Russian psycholinguistics from the standpoint of the current state of psycholinguistic science in the country are seen by us, first of all: in the development of research in various areas of linguistic consciousness, which will contribute to the development of an important concept of speech as a verbal model of non-linguistic consciousness, in which knowledge revealed by social practice and assigned by each member of society during its inculturation is consolidated for society and on its behalf; in the expansion of the problematics, which is formed under the influence of the growing intercultural communication in the world community, which inevitably involves the speech behavior of natural and artificial bilinguals in the new object area of psycholinguistics; in using the capabilities of national linguistic corpora in the interests of researchers studying the functioning of non-linguistic and linguistic consciousness in speech processes; in expanding research on the semantic perception of multimodal texts, the scope of which has greatly expanded in connection with the spread of the Internet as a means of communication in the life of modern society; in the inclusion of the problems of professional communication and professional activity in the object area of psycholinguistics in connection with the introduction of information technologies into public practice, entailing the emergence of new professions and new features of the professional ethos; in the further development of the theory of the mental lexicon (identifying the role of different types of knowledge in its formation and functioning, the role of the word as a unit of the mental lexicon in the formation of the image of the world, as well as the role of the natural / internal metalanguage and its specificity in speech activity); in the broad development of associative lexicography, which will meet the most diverse needs of society and cognitive sciences. The development of associative lexicography may lead to the emergence of such disciplines as associative typology, associative variantology, associative axiology; in expanding the spheres of applied use of psycholinguistics in social sciences, sociology, semasiology, lexicography, in the study of the brain, linguodidactics, medicine, etc. This book is a kind of summarizing result of the development of Russian psycholinguistics today. Each section provides a bibliography of studies on the relevant issue. The Appendix contains the scientometrics of leading Russian psycholinguists, basic monographs, psycholinguistic textbooks and dissertations defended in psycholinguistics. The content of the publications presented here is convincing evidence of the relevance of psycholinguistic topics and the effectiveness of the development of psycholinguistic problems in Russia.
Capitoli di libri sul tema "Non-natural reactions":
1
Stöckigt, Joachim, Zhong Chen e Martin Ruppert. "Enzymatic and Chemo-Enzymatic Approaches Towards Natural and Non-Natural Alkaloids: Indoles, Isoquinolines, and Others". In Natural Products via Enzymatic Reactions, 67–103. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/128_2010_80.
2
Lindsay, David M. "The Synthesis of Cyclic Ether-Containing Natural and Non-natural Products by Metathesis Reactions". In Topics in Heterocyclic Chemistry, 33–55. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/7081_2015_197.
3
Kadokawa, Jun-ichi. "α-Glucan Phosphorylase-Catalyzed Enzymatic Reactions to Precisely Synthesize Non-natural Polysaccharides". In ACS Symposium Series, 31–46. Washington, DC: American Chemical Society, 2020. http://dx.doi.org/10.1021/bk-2020-1373.ch002.
4
Alima, N., R. Snooks e J. McCormack. "Bio Scaffolds". In Proceedings of the 2021 DigitalFUTURES, 316–29. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-5983-6_29.
Abstract (sommario):
Abstract‘Bio Scaffolds’ explores a series of design tectonics that emerge from a co-creation between human, machine and natural intelligences. This research establishes an integral connection between form and materiality by enabling biological materials to become a co-creator within the design and fabrication process. In this research paper, we explore a hybrid between architectural aesthetics and biological agency by choreographing natural growth through form. ‘Bio Scaffolds’ explores a series of 3D printed biodegradable scaffolds that orchestrate both Mycelia growth and degradation through form. A robotic arm is introduced into the system that can respond to the organism’s natural behavior by injecting additional Mycelium culture into a series of sacrificial frameworks. Equipped with computer vision systems, feedback controls, scanning processes and a multi-functional end-effector, the machine tends to nature by reacting to its patterns of growth, moisture, and color variation. Using this cybernetic intelligence, developed between human, machine, and Mycelium, our intention is to generate unexpected structural and morphological forms that are represented via a series of 3D printed Mycelium enclosures. ‘Bio Scaffolds’ explores an interplay between biological and computational complexity through non anthropocentric micro habitats.
5
Morin, Olivier, Alberto Acerbi e Oleg Sobchuk. "Perché si muore nei romanzi: l’ipotesi della simulazione dell’ordalia". In La narrazione come incontro, 59–80. Florence: Firenze University Press, 2022. http://dx.doi.org/10.36253/979-12-215-0045-5.06.
Abstract (sommario):
What is fiction about, and what is it good for? An influential family of theories sees fiction as rooted in adaptive simulation mechanisms. In this view, our propensity to create and enjoy narrative fictions was selected and maintained due to the training that we get from mentally simulating situations relevant to our survival and reproduction. We put forward and test a precise version of this claim, the “ordeal simulation hypothesis”. It states that fictional narrative primarily simulates “ordeals”: situations where a person’s reaction might dramatically improve or decrease her fitness, such as deadly aggressions, or decisions on long-term matrimonial commitments. We study mortality in fictional and non-fictional texts as a partial test for this view. Based on an analysis of 744 extensive summaries of twentieth century American novels of various genres, we show that the odds of dying (in a given year) are vastly exaggerated in fiction compared to reality, but specifically more exaggerated for homicides as compared to suicides, accidents, war-related, or natural deaths. This evidence supports the ordeal simulation hypothesis but is also compatible with other accounts.
6
Gray, Peter, e Stephen K. Scott. "Thermokinetic Oscillations In A Closed System". In Chemical Oscillations and Instabilities, 83–111. Oxford University PressOxford, 1990. http://dx.doi.org/10.1093/oso/9780198556466.003.0004.
Abstract (sommario):
Abstract This chapter and chapter 5 study the prototypical thermokinetic oscillator. Thermal feedback replaces autocatalysis, and the Arrhenius temperature dependence of rate coefficients supplies non-linearity in the scheme In the preceding chapters we investigated the basic patterns of behaviour which might be exhibited by a reaction scheme which involved a certain form of chemical feedback under isothermal conditions. Here we make a similar analysis for systems with purely first-order chemical reactions but under conditions in which the heat produced by the natural exothermicity can lead to departures from isothermal operation. Feedback is then provided from thermal coupling as the increase in temperature of the reacting mixture leads to an increase in the local value of the reaction rate constant.
7
Scott, Stephen K. "Heterogeneous catalysis". In Chemical Chaos, 353–87. Oxford University PressOxford, 1991. http://dx.doi.org/10.1093/oso/9780198556510.003.0010.
Abstract (sommario):
Abstract Heterogeneous catalytic systems have seemed a natural and fertile field for non-linear behaviour and only solution-phase reactions have been more widely studied. The oxidation of carbon monoxide over many metal surfaces in particular seems to have been the subject of deep investigations perhaps because of its technological as well as fundamental significance. Heterogeneous catalysis is widely applied in the chemical industry as a whole-the petrochemical industry in particular-and so there has been both motivation and support for any increase in understanding and control of such reactions. It might also be added that many theoreticians have also taken advantage of the ‘grey areas’ of uncertainty in the form of appropriate reaction rate laws, using putative surface reactions (and their enzyme equivalents) as an excuse for almost any otherwise unbelievable but convenient polynomial or transcendental form.
8
Symons, M. C. R., e J. M. C. Gutteridge. "Natural iron ligands". In Free Radicals and Iron: Chemistry, Biology, and Medicine, 63–97. Oxford University PressOxford, 1998. http://dx.doi.org/10.1093/oso/9780198558927.003.0006.
Abstract (sommario):
Abstract Chapter 6 considers some of the naturally occurring iron ligands that are important in human biology and medicine. The body takes great care to sequester iron in non- or poorly reactive forms and, therefore, much of the discussion is focused on how safely sequestered iron can become biologically available to drive oxidative reactions. Here we define ‘natural’ iron chelators and complexing agents as those that occur in biological systems as well as those that are synthesized by microorganisms and subsequently isolated and purified for use in biological studies.
9
Brezonik, Patrick L., e William A. Arnold. "Complexation Reactions and Metal Ion Speciation". In Water Chemistry, 333–88. 2a ed. Oxford University PressNew York, 2022. http://dx.doi.org/10.1093/oso/9780197604700.003.0009.
Abstract (sommario):
Abstract This chapter deals with the second associative reaction type in ionic equilibria: complexation. After presenting definitions, the chapter describes ways to express equilibria of complexes and their components: metal ions and ligands. The chemical and ecological significance of complexes is summarized, along with the two types of complexes—inner and outer sphere. Factors affecting binding strengths of complexes are described, with attention to predictive relationships. Methods to solve and display complexation equilibria are explained, including simple examples solvable manually and computer methods for complicated situations in many natural waters. The roles of inorganic and organic ligands in metal ion speciation are described using examples ranging from soft to hard waters and high-ionic-strength seawater. The kinetics of complex formation and dissociation is treated. Although most formation reactions are fast, dissociation can be slow for strong complexes. Some metal-ligand exchange processes are slow enough to maintain non-equilibrium conditions for extended periods.
10
Kageyama, Hakuto. "Biological Activities of MAAs and their Applications 4: Anti-glycative Properties". In An Introduction to Mycosporine-Like Amino Acids, 94–101. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815136081123010010.
Abstract (sommario):
Advanced glycation end products (AGEs) are formed by a series of chemical reactions initiated by non-enzymatic glycation reactions. In this process, the reducing sugar binds to the free amino group of the protein. The formation of AGEs that accompany the aging process is thought to be associated with various diseases such as diabetes and Alzheimer's disease. A number of inhibitors derived from synthetic compounds and natural products have been developed and evaluated to prevent the formation of AGEs. Compared to synthetic compounds, natural products are considered to be relatively safe for human consumption, so there is an increasing demand for compounds derived from natural products. From this perspective, this chapter focuses on mycosporine-like amino acids as naturally occurring inhibitors against AGEs formation.
Atti di convegni sul tema "Non-natural reactions":
1
Shahsavan, Martia, Mohammadrasool Morovatiyan e J. Hunter Mack. "A Computational Investigation of Non-Premixed Combustion of Natural Gas Injected Into Mixture of Argon and Oxygen". In ASME 2018 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icef2018-9618.
Abstract (sommario):
Natural gas is traditionally considered as a promising fuel in comparison to gasoline due to the potential of lower emissions and significant domestic reserves. These emissions can be further diminished by using noble gases, such as argon, instead of nitrogen as the working fluid in internal combustion engines. Furthermore, the use of argon as the working fluid can increase the thermodynamic efficiency due to its higher specific heat ratio. In comparison to pre-mixed operation, the direct injection of natural gas enables the engine to reach higher compression ratios while avoiding knock. Using argon as the working fluid increases the in-cylinder temperature at top dead center and enables the compression ignition of natural gas. In this numerical study, the combustion quality and ignition behavior of methane injected into a mixture of oxygen and argon has been investigated using a three-dimensional transient model of a constant volume combustion chamber. A dynamic structure large eddy simulation model has been utilized to capture the behavior of the non-premixed turbulent gaseous jet. A reduced mechanism consists of 22-species and 104-reactions were coupled with the CFD solver. The simulation results show that the methane jet ignites at engine-relevant conditions when nitrogen is replaced by argon as the working fluid. Ignition delay times are compared across a variety of operating conditions to show how mixing affects jet development and flame characteristics.
2
Dalle Vacche, Sara. "Biobased composites from renewable monomers and cellulosic reinforcements by photoinduced processes". In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/ingy4050.
Abstract (sommario):
Polymeric materials are under tremendous pressure for improving their greenness: despite their important role in several essential aspects of human life, in public opinion they are mostly associated with single-use plastics pollution and use of fossil resources. Sustainable polymer-based materials may be prepared from biobased monomers and polymers, through photoinduced processes. Owing to low energy requirements, high reaction rates at room temperature, and low VOC emissions, photoinduced polymerization is recognized as a green technology. Among the biobased monomers explored in this field, those derived from cardanol (a natural phenolic lipid obtained from cashew nutshell liquid) and from unsaturated vegetable oils, such as soybean oil, are interesting for industrial applications, being commercially available.However, polymers obtained by photoinduced polymerization of biobased monomers often have low thermomechanical properties; biobased monomers are thus typically used as co-monomers to increase the biobased content of fossil-based polymers, in non-structural applications, such as coating or adhesives, or are added with reinforcements to obtain composite materials. The latter option is particularly interesting when natural fillers, such as cellulosic fibers, are used, thus obtaining fully biobased composites.
In our group we exploited photoinduced reactions to produce composites from biobased monomers, using wood-based microfibrillated cellulose and nanocellulose from hemp waste fibers as reinforcements. Two routes were explored: (i) epoxidized and (meth)acrylated monomers derived from cardanol and from soybean oil, were polymerized by photoinduced radical or cationic chain growth reactions; (ii) copolymer latexes obtained from derivatives of eugenol and coumarin were crosslinked through a photocycloaddition reaction. In the latter case, the potential reversibility of the crosslinking was explored in view of recyclability.
The photoinduced polymerization and crosslinking reactions were studied by Fourier Transform Infrared (FTIR) and UV-visible spectroscopies; high degrees of conversion were obtained. The thermal, mechanical, and functional properties of these composites make them interesting for e.g packaging applications.
3
Dalle Vacche, Sara. "Bio-based cationic waterborne polyurethane dispersions from high oleic soybean oil". In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/xdga8424.
Abstract (sommario):
Polymeric materials are under tremendous pressure for improving their greenness: despite their important role in several essential aspects of human life, in public opinion they are mostly associated with single-use plastics pollution and use of fossil resources. Sustainable polymer-based materials may be prepared from biobased monomers and polymers, through photoinduced processes. Owing to low energy requirements, high reaction rates at room temperature, and low VOC emissions, photoinduced polymerization is recognized as a green technology. Among the biobased monomers explored in this field, those derived from cardanol (a natural phenolic lipid obtained from cashew nutshell liquid) and from unsaturated vegetable oils, such as soybean oil, are interesting for industrial applications, being commercially available. However, polymers obtained by photoinduced polymerization of biobased monomers often have low thermomechanical properties; biobased monomers are thus typically used as co-monomers to increase the biobased content of fossil-based polymers, in non-structural applications, such as coating or adhesives, or are added with reinforcements to obtain composite materials. The latter option is particularly interesting when natural fillers, such as cellulosic fibers, are used, thus obtaining fully biobased composites. In our group we exploited photoinduced reactions to produce composites from biobased monomers, using wood-based microfibrillated cellulose and nanocellulose from hemp waste fibers as reinforcements. Two routes were explored: (i) epoxidized and (meth)acrylated monomers derived from cardanol and from soybean oil, were polymerized by photoinduced radical or cationic chain growth reactions; (ii) copolymer latexes obtained from derivatives of eugenol and coumarin were crosslinked through a photocycloaddition reaction. In the latter case, the potential reversibility of the crosslinking was explored in view of recyclability. The photoinduced polymerization and crosslinking reactions were studied by Fourier Transform Infrared (FTIR) and UV-visible spectroscopies; high degrees of conversion were obtained. The thermal, mechanical, and functional properties of these composites make them interesting for e.g., packaging applications.
4
Lu, Xijia, e Ting Wang. "Review of Coal-to-Synthetic Natural Gas (SNG) Production Methods and Modeling of SNG Production in an Entrained-Flow Gasifer". In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57857.
Abstract (sommario):
In this paper, the coal-to-synthetic natural gas (SNG) technologies have been reviewed. Steam-oxygen gasification, hydrogasification, and catalytic steam gasification are the three major gasification processes used in coal-to-SNG production. So far, only the steam-oxygen gasification process is commercially proven by installing a catalytic methanation reactor downstream of the gasification process after syngas is produced, cleaned, and shifted to achieve an appropriate H2/CO ratio for methanation reaction. This process is expensive, less efficient, and time consuming. Ideally, it will be more effective and economic if methanation could be completed in an once-through entrained-flow gasifier. Technically, this idea is challenging because an effective gasification process is typically operated in a high-pressure and high-temperature condition, which is not favorable for methanation reaction, which is exothermic. To investigate this idea, a computational model is established and a sensitivity study of methanation reactions with and without catalysts are conducted in this study. In modeling the methanation process in a gasifier, correct information of the reaction rates is extremely important. Most of known methanation reaction rates are tightly linked to the catalysts used. Since the non-catalytic reaction rates for methanation are not known in a gasifer and the issues are compounded by the fact that inherent minerals in coal ashes can also affect the methanation kinetics, modeling of methanation in an entrained-flow gasifier becomes very challenging. Considering these issues, instead of trying to obtain the correct methnation reaction rate, this study attempts to use computational model as a convenient tool to investigate the sensitivity of methane production under a wide range methanation reaction rates with and without catalysts. From this sensitivity study, it can be learned that the concept of implementing direct methanation in a once-through entrained-flow gasifier may not be attractive due to competitions of other reactions in a high-temperature environment. The production of SNG is limited to about 18% (vol) with catalytic reaction with a pre-exponential factor A in the order of 107. A further increase of the value of A to 1011 doesn’t result in more production of SNG. This SNG production limit could be caused by the high-temperature and short residence time (3–4 seconds) in the entraind-flow gasifier.
5
Toema, Mohamed, e Kirby S. Chapman. "Modeling of Lambda Sensor Output With Exhaust Gas Mixtures From Natural Gas-Fueled Engines". In ASME 2011 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/icef2011-60188.
Abstract (sommario):
The increasingly strict emission regulations may require implementing Non-Selective Catalytic Reduction (NSCR) system as a promising emission control technology for stationary rich burn spark ignition engines. Many recent investigations used NSCR systems for stationary natural gas fueled engines showed that NSCR systems were unable to consistently control the emissions level below the compliance limits. Modeling of NSCR components to better understand, and then exploit, the underlying physical processes that occur in the lambda sensor and the catalyst media is now considered an essential step toward the required NSCR system performance. This paper presents the work done to date on a modeling of lambda sensor that provides feedback to the air-to-fuel controller. Several recent experimental studies indicate that the voltage signal from the lambda sensor may not be interpreted correctly because of the physical nature in the way the sensor senses the exhaust gas concentration. Correct interpretation of the sensor output signal is necessary to achieve consistently low emissions level. The goal of this modeling study is to improve the understanding of the physical processes that occur within the sensor, investigate the cross-sensitivity of various exhaust gas species on the sensor performance, and finally this model serves as a tool to improve NSCR control strategies. This model simulates the output from a planar switch type lambda sensor. The model consists of three modules. The first module models the multi-component mass transport through the sensor protective layer. Diffusion fluxes are calculated using the Maxwell-Stefan equation. The second module includes all the surface catalytic reactions that take place on the sensor platinum electrodes. All kinetic reactions are modeled based on the Langmuir-Hinshelwood kinetic mechanism. The model incorporates for the first time methane catalytic reactions on the sensor platinum electrode. The third module is responsible for simulating the reactions that occur on the electrolyte material and determine the sensor output voltage. The model results are validated using field test data obtained from a mapping study of a natural gas-fueled engine equipped with NSCR system. The data showed that the lambda sensor output voltage is influenced by the reducing species concentration, such as carbon monoxide (CO) and hydrogen (H2). The results from the developed model and the experimental data showed strong correlations between CO and H2 with the sensor output voltage within the lambda operating range between 0.994 to 1.007 (catalytic converter operating window). This model also showed that methane does not significantly influence the lambda sensor performance compared to the effect of CO and H2.
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Piestrzyński, Adam, Jadwiga Pieczonka e Edward Chruściel. "Model for Long-Term Stabilization and Isolation of Low Level Uranium Waste". In ASME 2001 8th International Conference on Radioactive Waste Management and Environmental Remediation. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/icem2001-1261.
Abstract (sommario):
Abstract Problems arising from uranium dispersion from mines and mine tailings, and the remediation of uranium contaminated areas, are discussed in this paper. In an experimental remediation study, a mixture of 70 vol.% of uraniferous mining wastes and 30 vol.% of a natural ceramic were used. The preliminary observations are discussed, and a model is proposed for the long term stabilization of mining tailings. Observations and monitoring of contaminated sites carried out during the last 25 years have revealed local impacts of uranium on the environment in Lower Silesia, Poland. Uranium pollution is limited to waste dumps, mine tailings, and their close vicinities at Kowary Podgórze, Radoniów, Kopaniec and Kletno. Uranium dispersion takes place mechanically due to transport by river waters, chemically by rain and ground waters, and anthropogenically when the wastes are utilized in construction. Floods are an additional mechanism responsible for the mechanical dispersion of uranium. As a result of these uranium transport mechanisms, in order to minimize the impacts of uranium on the environment, the covering of dumps with non-radioactive material is suitable only for sites located away from populated areas. Redox reactions have been observed at the Kowary tailings. During these reactions, iron hydroxide (goethite), hematite, and gypsum, are precipitated as solids. These observations provide a good prognosis for the long-term stabilization of radionuclides which can be incorporated into proposals for the construction of tailings sites. Using Eh-pH diagrams (system U-C-O-H, 25°C, 1 bar), UO2 is stable over the whole range of naturally occurring pHs, and is affected by Eh only in the range −0.4 to +0.1 volts in acidic environments, and below −0.4v in basal environments. BaSO4 and RaSO4 are stable under almost the same conditions as UO2. An environmentally significant redox boundary (FeS2 versus Fe2O3) occurs in the middle of the UO2 stability field. The geochemical and environmental behaviour of the elements discussed above suggest a mechanism for stabilizing radionuclides within stored wastes. The solidification of wastes should occur concurrently with naturally occurring redox reactions. During oxidation, an active iron-hydroxide gel is produced. This gel is then dehydrated and converted into limonite (a mixed compound), a monohydrate (goethite), hydro-hematite (Fe2O3·1/2H2O) and hematite (Fe2O3). This reaction occurs in neutral or weakly acidic environments. A key problem in the proposed remediation project, therefore, is pH stabilization in order to maintain the required environment for oxidation and cementation reactions. In order to achieve such an environment and to stabilize the reactions, a construction method is proposed for new waste storage systems, based on mixed layers of waste and barrier components composed of natural materials. The presence of CaO or Ca(OH)2 and anhydrite in the proposed internal membrane will reduce the vertical migration of sulphates. Redox reactions will be responsible for the secondary precipitation (reduction) of uranyl. These same reactions occur naturally during the precipitation of uranium ores. Iron oxidation is the other process in the redox pair required to reduce [UO2]+2 to UO2. The resultant pitchblende is insoluble in normal oxidizing environments. To minimize the dissolution of UO2 by sulphuric acid generated during the iron oxidation reaction, the construction of pH active membranes containing calcium oxide or hydroxide are recommended. These compounds will react with the free acid to precipitate gypsum. Although several elements can be mobilized as a result of oxidation, radium remains in insoluble solid phases such as the common Ca, Ba and Sr sulphates.
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Toema, Mohamed, e Kirby S. Chapman. "Interpreting the Lambda Sensor Output Signal to Control Emissions From Natural Gas Fueled Engines". In ASME 2010 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/icef2010-35164.
Abstract (sommario):
This paper presents the work done to date on a modeling study of the Non-Selective Catalytic Reduction (NSCR) system. Several recent experimental studies indicate that the voltage signal from the heated exhaust gas oxygen sensor commonly used to control these emission reduction systems may not be interpreted correctly because of the physical nature in the way the sensor senses the exhaust gas concentration. While the current signal interpretation may be satisfactory for modest NOX and CO reduction, an improved understanding of the signal is necessary to achieve consistently low NOX and CO emission levels. The increasingly strict emission regulations may require implementing NSCR as a promising emission control technology for stationary spark ignition engines. Many recent experimental investigations that used NSCR systems for stationary natural gas fueled engines showed that NSCR systems were unable to consistently control the emissions level below the compliance limits. Modeling of NSCR components to better understand, and then exploit, the underlying physical processes that occur in the lambda sensor and the catalyst media is now considered an essential step toward improving NSCR system performance. This paper focuses only on the lambda sensor that provides feedback to the air-to-fuel ratio controller. The goals of this modeling study are: • Improve the understanding of the transport phenomena and electrochemical processes that occur within the sensor. • Investigate the cross-sensitivity of exhaust gases from natural gas fueled engines on the sensor performance. • Serve as a tool for improving NSCR control strategies. This model simulates the output from a planar switch type lambda sensor. The model consists of three modules. The first module models the multi-component mass transport through the sensor protective layer. A one dimensional mass conservation equation is used for each exhaust gas species. Diffusion fluxes are calculated using the Maxwell-Stefan equation. The second module includes all the surface catalytic reactions that take place on the sensor platinum electrodes. All kinetic reactions are modeled based on the Langmuir-Hinshelwood kinetic mechanism. The third module is responsible for simulating the reactions that occur on the electrolyte material and determining the sensor output voltage. The details of these three modules as well as a parametric study that investigates the sensitivity of the output voltage signal to various exhaust gas parameters is provided in the paper.
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Lu, Dennis Y., e Edward J. Anthony. "Combustion Characteristics of Natural Gas in a Circulating Fluidized Bed". In 17th International Conference on Fluidized Bed Combustion. ASMEDC, 2003. http://dx.doi.org/10.1115/fbc2003-053.
Abstract (sommario):
Recently there has been interest in extending the application of fluidized bed combustors (FBCs) to fuels with difficult handling properties or ones that are associated with non-conventional air pollutant problems. These fuels, such as biomass, plastic wastes, black liquors and heavy liquid fuels, have very high volatiles contents and, because they are often treated as easily-burned materials, they have received much less attention than has been given say to the combustion processes for char in FBCs. Understanding their gas-phase chemistry is helpful in optimizing their combustion. This paper describes the study of natural gas combustion in a fluidized bed as a simple model for studying gas-phase reactions involving C/H/N/O chemistry in the absence of char. The experimental work was conducted using a pilot-scale CFBC unit. Combustion characteristics and emissions were investigated by varying the operating conditions and in particular the combustion temperature, fluidizing velocity and bed material. The results indicated that fluidized bed combustion chemistry is associated with superequilibrium free radical processes, similar to high-temperature flame systems. In this system, prompt-NO mechanisms are the only routes for NO formation and this work shows that they can lead to significant NOx production.
9
Li, Rui, e Shichang Liu. "Study on Selection Method of Shielding Nuclides in Nuclear Reactor Based on Non-Dominated Sorting". In 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-90902.
Abstract (sommario):
Abstract In the reactor, the main purpose of radial shielding was to protect the internal structure and staff from radiation damage. The good shielding material must have both a high elastic scattering cross-section and a high absorption cross-section to reduce the radiation level outside the reactor core and ensure the safety of workers and equipment outside the reactor. In this paper, a new type selection scheme of shielding material was proposed, which read the reaction cross-sections of all-natural stable nuclides in the ENDF/B-VII database, calculated the single group cross-sections of various reactions of all nuclides by the integral method according to the neutron energy spectrum. Then ranked the nuclides with different cross-sections as the target, to screen the nuclides with the best neutron and photon shielding effect. In this paper, a typical Monte Carlo particle transport program was used for preliminary verification, which was applied to the energy spectrum of the pressurized water reactor and sodium-cooled fast reactor. The results show that for neutron shielding, photon shielding, and neutron-photon shielding, in the thermal neutron spectrum, the coincidence rates between the non-dominated sorting scheme and the Monte Carlo method were 95 %, 98.95 %, and 94.87 % respectively, and in the fast neutron spectrum, the coincidence rates between the non-dominated sorting scheme and the Monte Carlo method were 72.5 %, 95.79 %, and 82.5 % respectively. The calculation time of non-dominated sorting was less than 3% of that of the Monte Carlo method. It provided an efficient method for the selection of shielding nuclides in advanced reactors and had engineering application significance.
10
Strasser, Wayne. "Can Naturally Pulsating Prefilming Slurry Atomization Be Enhanced by Artificial External Modulation?" In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-4882.
Abstract (sommario):
Abstract Under certain conditions in preferred three-stream geometries, a non-Newtonian airblast atomization flowfield violently pulses (axially and radially) by self-generating and self-sustaining interfacial instability mechanisms. The pulsing is severe enough to send acoustic waves throughout feed piping networks. The most recent work on this system instructed that exothermic chemical reactions enhance this moderate Mach number atomization. Explored herein is the potential to further enhance reaction-assisted disintegration by independently superimposing both sinusoidal and randomized mass flow fluctuations of +/− 50% of the mean onto otherwise constant gas feed streams. Two nozzle geometries (low versus high prefilming distance) and multiple superimposed feed frequencies (ranging from below to above the naturally dominant tone) are considered for each gas stream, making twenty-one total long-running unsteady PLIC-VOF CFD models. Droplet size, plus nine other temporal measures, were considered for assessing atomizer performance in our energy production process. Results indicate that superimposed frequencies have potential to enhance chaotic atomization in a statistically significant manner. Depending on the geometry, the largest effect was about a 10% reduction in droplet size; however, some combinations experienced a droplet size increase. Only marginal differences were seen in the nine other measures, such as injector face heat exposure. In addition to the immediate industrial benefit from modulation, dramatic changes in acoustics were produced by imposed feed perturbations at frequencies lower than the natural tone. A detailed study of start-up flow reveals new mechanisms which explain performance differences.
Rapporti di organizzazioni sul tema "Non-natural reactions":
1
Chapman e Toema. PR-266-09211-R01 Physics-Based Characterization of Lambda Sensor from Natural Gas Fueled Engines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), novembre 2012. http://dx.doi.org/10.55274/r0010022.
Abstract (sommario):
The increasingly strict air emission regulations may require implementing Non-Selective Catalytic Reduction (NSCR) systems as a promising emission control technology for stationary rich burn spark ignition engines. Many recent experimental investigations that used NSCR systems for stationary natural gas fueled engines showed that NSCR systems were unable to consistently control the exhaust emissions level below the compliance limits. Modeling of NSCR components to better understand, and then exploit, the underlying physical processes that occur in the lambda sensor and the catalyst media is now considered an essential step toward improving NSCR system performance. This report focuses on modeling the lambda sensor that provides feedback to the air-to-fuel ratio controller. Correct interpretation of the sensor output signal is necessary to achieve consistently low emissions level. The goal of this modeling study is to improve the understanding of the physical processes that occur within the sensor, investigate the cross-sensitivity of various exhaust gas species on the sensor performance, and finally this model serves as a tool to improve NSCR control strategies. This model simulates the output from a planar switch type lambda sensor. The model consists of three modules. The first module models the multi-component mass transport through the sensor protective layer. The second module includes all the surface catalytic reactions that take place on the sensor platinum electrodes. The third module is responsible for simulating the reactions that occur on the electrolyte material and determine the sensor output voltage.
2
Rouseff, Russell L., e Michael Naim. Characterization of Unidentified Potent Flavor Changes during Processing and Storage of Orange and Grapefruit Juices. United States Department of Agriculture, settembre 2002. http://dx.doi.org/10.32747/2002.7585191.bard.
Abstract (sommario):
Citrus juice flavor quality traditionally diminishes after thermal processing and continuously during storage. Our prior studies found that four of the five most potent off-aromas formed during orange juice storage had not been identified. The primary emphasis of this project was to characterize and identify those potent flavor degrading aroma volatiles so that methods to control them could be developed and final flavor quality improved. Our original objectives included: 1 Isolate and characterize the most important unidentified aroma impact compounds formed or lost during pasteurization and storage. 2. Determination of thiamine and carotenoid thermal decomposition and Strecker degradation pathways in model solutions as possible precursors for the unidentified off-flavors. 3. Evaluate the effectiveness of an "electronic nose" to differentiate the headspace aromas of from untreated and heat pasteurized orange and grapefruit juices. 4. Use model systems of citrus juices to investigate the three possible precursor pathways (from 2) for flavor impact compounds formed or lost during pasteurization or storage. RESULTS - The components responsible for citrus storage off flavors and their putative precursors have now been identified. Certain carotenoids (b-carotene) can thermally degrade to produce b-ionone and b-damascenone which are floral and tobacco smelling respectively. Our GC-O and sensory experiments indicated that b-damascenone is a potential storage off-flavor in orange juice. Thiamine (Vitamin B1) degradation produces 2-methyl-3-furan thiol, MFT, and its dimer bis(2- methyl-3-furyl) disulfide which both produce meaty, savory aromas. GC-O and sensory studies indicated that MFT is another storage off-flavor. Methional (potato aroma) is another off flavor produced primarily from the reaction of the native amino acid, methionine, and oxidized ascorbic acid (vitamin C). This is a newly discovered pathway for the production of methional and is more dominant in juices than the classic Maillard reaction. These newly identified off flavors diminish the flavor quality of citrus juices as they distort the flavor balance and introduce non-typical aromas to the juice flavor profile. In addition, we have demonstrated that some of the poor flavor quality citrus juice found in the market place is not only from the production of these and other off flavors but also due to the absence of desirable flavor components including several potent aldehydes and a few esters. The absence of these compounds appears to be due to incomplete flavor volatile restoration after the making of juice concentrates. We are the first to demonstrate that not all flavor volatiles are removed along with water in the production of juice concentrate. In the case of grapefruit juice we have documented which flavor volatiles are completely removed, which are partially removed and which actually increase because of the thermal process. Since more that half of all citrus juices is made into concentrate, this information will allow producers to more accurately restore the original flavor components and produce a juice with a more natural flavor. IMPLICATIONS - We have shown that the aroma of citrus juices is controlled by only 1-2% of the total volatiles. The vast majority of other volatiles have little to no direct aroma activity. The critical volatiles have now been identified. The ability to produce high quality citrus juices requires that manufacturers know which chemical components control aroma and flavor. In addition to identifying the critical flavor components (both positive and negative), we have also identified several precursors. The behavior of these key aroma compounds and their precursors during common manufacturing and storage conditions has been documented so manufacturers in Israel and the US can alter production practices to minimize the negative ones and maximize the positive ones.
3
Moghimi, Gholamreza, e Nicos Makris. Response Modification of Structures with Supplemental Rotational Inertia. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, gennaio 2024. http://dx.doi.org/10.55461/tihv1701.
Abstract (sommario):
Tall, multistory, buildings are becoming increasingly popular in large cities as a result of growing urbanization trends (United Nations Department of Economic and Social Affairs 2018). As cities continue to grow, many of them along the coasts of continents which are prone to natural hazards, the performance of tall, flexible buildings when subjected to natural hazards is a pressing issue with engineering relevance. The performance of structures when subjected to dynamic loads can be enhanced with various response modification strategies which have been traditionally achieved with added stiffness, flexibility, damping and strength (Kelly et al. 1972; Skinner et al. 1973, 1974; Clough and Penzien 1975; Zhang et al. 1989; Aiken 1990; Whittaker et al. 1991; Makris et al. 1993a,b; Skinner et al. 1993; Inaudi and Makris 1996; Kelly 1997; Soong and Dargush 1997; Constantinou et al. 1998; Makris and Chang 2000a; Chang and Makris 2000; Black et al. 2002, 2003; Symans et al. 2008; Sarlis et al. 2013; Tena-Colunga 1997). Together with the elastic spring that produces a force proportional to the relative displacement of its end-nodes and the viscous dashpot that produces a force proportional to the relative velocity of its end-nodes; the inerter produces a force proportional to the relative acceleration of its end-nodes and emerges as the third elementary mechanical element (in addition to the spring and dashpot) capable for modifying structural response. Accordingly, in this report we examine the seismic performance of multistory and seismically isolated structures when equipped with inerters. In view that the inerter emerges as the third elementary mechanical element for the synthesis of mechanical networks, in Chapter 2 we derive the basic frequency- and time-response functions of the inerter together with these of the two-parameter inertoelastic and inertoviscous mechanical networks. Chapter 3 examines the response of a two-degree-of-freedom (2DOF) structure where the first story is equipped with inerters. Both cases of a stiff and a compliant support of the inerters are examined. The case of two parallel clutching inerters is investigated and the study concludes that as the compliance of the frame that supports the inerters increases, the use of a single inerter offers more favorable response other than increasing the force transferred to the support frame. Chapter 4 examines the seismic response analysis of the classical two-degree-of-freedom isolated structure with supplemental rotational inertia (inerter) in its isolation system. The analysis shows that for the “critical” amount of rotational inertia which eliminates the participation of the second mode, the effect of this elimination is marginal on the structural response since the participation of the second mode is invariably small even when isolation systems without inerters are used. Our study, upon showing that the reaction force at the support of the inerter is appreciable, proceeds with a non-linear response analysis that implements a state-space formulation which accounts for the bilinear behavior of practical isolation system (single concave sliding bearings or lead-rubber bearings) in association with the compliance of the support of the inerter. Our study concludes that supplemental rotational inertia aggravates the displacement and acceleration response of the elastic superstructure and as a result, for larger isolation periods (Tb > 2.5s) the use of inerters in isolation systems is not recommended. Chapter 5 first examines the response analysis of a SDOF elastoplastic and bilinear structure and reveals that when the yielding structure is equipped with supplemental rotational inertia, the equal- displacement rule is valid starting from lower values of the pre-yielding period given that the presence of inerters lengthens the apparent pre-yielding period. The analysis concludes that sup- plemental rotational inertia emerges as an attractive response modification strategy for elastoplastic and bilinear SDOF structures with pre-yielding periods up to T1 = 1.5sec. For larger pre-yielding periods (say T1 > 2.0sec), the effectiveness of inerters to suppress the inelastic response of 2DOF yielding structures reduces; and for very flexible first stories; as in the case of isolated structures examined in chapter 4, the use of inerter at the first level (isolation system) is not recommended. Finally, chapter 6 shows that, in spite of the reduced role of inerters when placed at floor levels other than the first level (they no-longer suppress the induced ground acceleration nor they can eliminate the participation of higher modes), they still manifest a unique role since it is not possible to replace a structure with solitary inerters at higher levels with an equivalent traditional structure without inerters.