Littérature scientifique sur le sujet « Inhibitors, Robustness »
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Articles de revues sur le sujet "Inhibitors, Robustness"
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Fuentes, Miguel A., et David C. Krakauer. « The evolution of developmental patterning under genetic duplication constraints ». Journal of The Royal Society Interface 5, no 19 (26 juin 2007) : 237–45. http://dx.doi.org/10.1098/rsif.2007.1074.
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Of considerable interest are the evolutionary and developmental origins of complex, adaptive structures and the mechanisms that stabilize these structures. We consider the relationship between the evolutionary process of gene duplication and deletion and the stability of morphogenetic patterns produced by interacting activators and inhibitors. We compare the relative stability of patterns with a single activator and inhibitor (two-dimensional system) against a ‘redundant’ system with two activators or two inhibitors (three-dimensional system). We find that duplication events can both expand and contract the space of patterns. We study developmental robustness in terms of stochastic escape times from this space, also known as a ‘canalization potential’. We embed the output of pattern formation into an explicit evolutionary model of gene duplication, gene loss and variation in the steepness of the canalization potential. We find that under all constant conditions, the system evolves towards a preference for steep potentials associated with low phenotypic variability and longer lifespans. This preference leads to an overall decrease in the density of redundant genotypes as developmental robustness neutralizes the advantages of genetic robustness.
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Teixeira, Vanessa S., Suéllen P. H. Azambuja, Priscila H. Carvalho, Fátima A. A. Costa, Patricia R. Kitaka, Claudia Stekelgerb, Silvio R. Andrietta, Maria G. S. Andrietta et Rosana Goldbeck. « Robustness and Ethanol Production of Industrial Strains of Saccharomyces cerevisiae Using Different Sugarcane Bagasse Hydrolysates ». Journal of Applied Biotechnology 7, no 1 (7 mai 2019) : 23. http://dx.doi.org/10.5296/jab.v7i1.14599.
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Sugarcane bagasse is one of the main lignocellulosic raw materials used for the production of second-generation ethanol. Technological studies on fermentation processes have focused on the search for and development of more robust microorganisms that are able to produce bioethanol efficiently and are resistant to the main fermentation inhibitors. The purpose of this study was to evaluate the robustness and ethanol production of industrial strains of Saccharomyces cerevisiae using acid, alkaline, and enzymatic sugarcane bagasse hydrolysates. Hydrolysis was carried out to release fermentable sugars from sugarcane bagasse. Fermentations were performed in shake flasks containing sugarcane hydrolysates supplemented with 150 g L−1 glucose to evaluate the kinetic parameters of the reaction. Inhibitor tolerance was evaluated by incubating cells with different concentrations of inhibitors in 96-well plates. The biomass yield on substrate, ethanol yield on substrate, and ethanol productivity of the six strains were higher in 0.5% acid, 0.5% alkaline, and enzymatic hydrolysates (i.e., under milder conditions). The SA-1 (Santa Adélia-1) strain had a better performance in comparison with the other strains for its ability to produce ethanol in a very severe condition (7% acid hydrolysis) and for its robustness in growing at several inhibitor concentrations.
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Meeks, Shannon L., Alexander M. Sevy, John F. Healey, Wei Deng, P. Clint Spiegel et Renhao Li. « Cooperative Binding Of Anti-Factor VIII Inhibitors and Induced Conformational Change Detected By Hydrogen-Deuterium Exchange Mass Spectrometry ». Blood 122, no 21 (15 novembre 2013) : 1088. http://dx.doi.org/10.1182/blood.v122.21.1088.1088.
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Abstract The development of anti-factor VIII (fVIII) antibodies (inhibitors) is a significant complication in the management of patients with hemophilia A leading to significant increases in morbidity and treatment cost. Using a panel of anti-fVIII monoclonal antibodies to different epitopes on fVIII, we recently have shown that epitope specificity, inhibitor kinetics, and time to maximum inhibition are more important than inhibitor titer in predicting response to fVIII and the combination of fVIII and recombinant factor VIIa. Thus the ability to quickly map the epitope spectrum of patient plasma using a clinically feasible assay may fundamentally change how clinicians approach the treatment of high-titer inhibitor patients. To this end, we have characterized the binding epitopes of 4 monoclonal antibodies (MAbs) targeted against fVIII C2 domain by hydrogen-deuterium exchange coupled with liquid chromatography-mass spectrometry (HDX-MS). MAbs included both classical (inhibiting binding of fVIII to von Willebrand factor and phospholipid) and non-classical inhibitors (inhibiting activation of fVIII), which target separate regions of fVIII C2 domain and have distinct inhibitory mechanisms. HDX-MS analysis showed clear differences in binding patterns between classical and non-classical inhibitors, centering on the protruding hydrophobic loop at Met2199. The binding epitopes of classical and non-classical inhibitors mapped by HDX-MS agree well with previously reported ones characterized by structural studies and mutagenesis analysis. Classical and non-classical inhibitors could be distinguished by a limited subset of C2-derived peptides, simplifying analysis significantly. In addition, HDX-MS was able to detect subtle differences in binding patterns of various classical inhibitors, based on the HDX protection pattern around the hydrophobic loop at Leu2251. Interestingly, two MAbs, G99 and 3E6, exhibited an observable shift in HDX protection when bound to C2 as a ternary complex, as opposed to when bound individually, thus providing evidence for cooperative binding of these two MAbs (Figure 1). In summary, our results demonstrate the effectiveness and robustness of the HDX-MS method in the rapid epitope mapping of fVIII inhibitors. This method can be expanded to map epitopes of inhibitors against other domains of fVIII, potentially leading to a more personalized treatment of hemophilia A patients.Figure 1Figure 1. Disclosures: No relevant conflicts of interest to declare.
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Zhao, Junnan, Lu Zhu, Weineng Zhou, Lingfeng Yin, Yuchen Wang, Yuanrong Fan, Yadong Chen et Haichun Liu. « In silico Prediction of Inhibitory Constant of Thrombin Inhibitors Using Machine Learning ». Combinatorial Chemistry & ; High Throughput Screening 21, no 9 (21 janvier 2019) : 662–69. http://dx.doi.org/10.2174/1386207322666181220130232.
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Background: Thrombin is the central protease of the vertebrate blood coagulation cascade, which is closely related to cardiovascular diseases. The inhibitory constant Ki is the most significant property of thrombin inhibitors. Method: This study was carried out to predict Ki values of thrombin inhibitors based on a large data set by using machine learning methods. Taking advantage of finding non-intuitive regularities on high-dimensional datasets, machine learning can be used to build effective predictive models. A total of 6554 descriptors for each compound were collected and an efficient descriptor selection method was chosen to find the appropriate descriptors. Four different methods including multiple linear regression (MLR), K Nearest Neighbors (KNN), Gradient Boosting Regression Tree (GBRT) and Support Vector Machine (SVM) were implemented to build prediction models with these selected descriptors. Results: The SVM model was the best one among these methods with R2=0.84, MSE=0.55 for the training set and R2=0.83, MSE=0.56 for the test set. Several validation methods such as yrandomization test and applicability domain evaluation, were adopted to assess the robustness and generalization ability of the model. The final model shows excellent stability and predictive ability and can be employed for rapid estimation of the inhibitory constant, which is full of help for designing novel thrombin inhibitors.
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Avval, Zhila, Eslam Pourbashir, Mohammad Ganjali et Parviz Norouzi. « Application of genetic algorithm - multiple linear regressions to predict the activity of RSK inhibitors ». Journal of the Serbian Chemical Society 80, no 2 (2015) : 187–96. http://dx.doi.org/10.2298/jsc140523064a.
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This paper deals with developing a linear quantitative structure-activity relationship (QSAR) model for predicting the RSK inhibition activity of some new compounds. A dataset consisting of 62 pyrazino [1,2-?] indole, diazepino [1,2-?] indole, and imidazole derivatives with known inhibitory activities was used. Multiple linear regressions (MLR) technique combined with the stepwise (SW) and the genetic algorithm (GA) methods as variable selection tools was employed. For more checking stability, robustness and predictability of the proposed models, internal and external validation techniques were used. Comparison of the results obtained, indicate that the GA-MLR model is superior to the SW-MLR model and that it isapplicable for designing novel RSK inhibitors.
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Green, Keith D., Ankita Punetha, Caixia Hou, Sylvie Garneau-Tsodikova et Oleg V. Tsodikov. « Probing the Robustness of Inhibitors of Tuberculosis Aminoglycoside Resistance Enzyme Eis by Mutagenesis ». ACS Infectious Diseases 5, no 10 (21 août 2019) : 1772–78. http://dx.doi.org/10.1021/acsinfecdis.9b00228.
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Kremb, Stephan, Markus Helfer, Werner Heller, Dieter Hoffmann, Horst Wolff, Andrea Kleinschmidt, Sabine Cepok, Bernhard Hemmer, Jörg Durner et Ruth Brack-Werner. « EASY-HIT : HIV Full-Replication Technology for Broad Discovery of Multiple Classes of HIV Inhibitors ». Antimicrobial Agents and Chemotherapy 54, no 12 (27 septembre 2010) : 5257–68. http://dx.doi.org/10.1128/aac.00515-10.
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ABSTRACT HIV replication assays are important tools for HIV drug discovery efforts. Here, we present a full HIV replication system (EASY-HIT) for the identification and analysis of HIV inhibitors. This technology is based on adherently growing HIV-susceptible cells, with a stable fluorescent reporter gene activated by HIV Tat and Rev. A fluorescence-based assay was designed that measures HIV infection by two parameters relating to the early and the late phases of HIV replication, respectively. Validation of the assay with a panel of nine reference inhibitors yielded effective inhibitory concentrations consistent with published data and allowed discrimination between inhibitors of early and late phases of HIV replication. Finer resolution of the effects of reference drugs on different steps of HIV replication was achieved in secondary time-of-addition assays. The EASY-HIT assay yielded high Z′ scores (>0.9) and signal stabilities, confirming its robustness. Screening of the LOPAC1280 library identified 10 compounds (0.8%), of which eight were known to inhibit HIV, validating the suitability of this assay for screening applications. Studies evaluating anti-HIV activities of natural products with the EASY-HIT technology led to the identification of three novel inhibitory compounds that apparently act at different steps of HIV-1 replication. Furthermore, we demonstrate successful evaluation of plant extracts for HIV-inhibitory activities, suggesting application of this technology for the surveillance of biological extracts with anti-HIV activities. We conclude that the EASY-HIT technology is a versatile tool for the discovery and characterization of HIV inhibitors.
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Halim, Sobia Ahsan, Sumaira Jabeen, Ajmal Khan et Ahmed Al-Harrasi. « Rational Design of Novel Inhibitors of α-Glucosidase : An Application of Quantitative Structure Activity Relationship and Structure-Based Virtual Screening ». Pharmaceuticals 14, no 5 (19 mai 2021) : 482. http://dx.doi.org/10.3390/ph14050482.
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α-Glucosidase is considered a prime drug target for Diabetes Mellitus and its inhibitors are used to delay carbohydrate digestion for the treatment of diabetes mellitus. With the aim to design α-glucosidase inhibitors with novel chemical scaffolds, three folds ligand and structure based virtual screening was applied. Initially linear quantitative structure activity relationship (QSAR) model was developed by a molecular operating environment (MOE) using a training set of thirty-two known inhibitors, which showed good correlation coefficient (r2 = 0.88), low root mean square error (RMSE = 0.23), and cross-validated correlation coefficient r2 (q2 = 0.71 and RMSE = 0.31). The model was validated by predicting the biological activities of the test set which depicted r2 value of 0.82, indicating the robustness of the model. For virtual screening, compounds were retrieved from zinc is not commercial (ZINC) database and screened by molecular docking. The best docked compounds were chosen to assess their pharmacokinetic behavior. Later, the α-glucosidase inhibitory potential of the selected compounds was predicted by their mode of binding interactions. The predicted pharmacokinetic profile, docking scores and protein-ligand interactions revealed that eight compounds preferentially target the catalytic site of α-glucosidase thus exhibit potential α-glucosidase inhibition in silico. The α-glucosidase inhibitory activities of those Hits were predicted by QSAR model, which reflect good inhibitory activities of these compounds. These results serve as a guidelines for the rational drug design and development of potential novel anti-diabetic agents.
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Zhang, Meng, Yiwei Lai, Vladislav Krupalnik, Pengcheng Guo, Xiangpeng Guo, Jianguo Zhou, Yan Xu et al. « β-Catenin safeguards the ground state of mousepluripotency by strengthening the robustness of the transcriptional apparatus ». Science Advances 6, no 29 (juillet 2020) : eaba1593. http://dx.doi.org/10.1126/sciadv.aba1593.
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Mouse embryonic stem cells cultured with MEK (mitogen-activated protein kinase kinase) and GSK3 (glycogen synthase kinase 3) inhibitors (2i) more closely resemble the inner cell mass of preimplantation blastocysts than those cultured with SL [serum/leukemia inhibitory factor (LIF)]. The transcriptional mechanisms governing this pluripotent ground state are unresolved. Release of promoter-proximal paused RNA polymerase II (Pol2) is a multistep process necessary for pluripotency and cell cycle gene transcription in SL. We show that β-catenin, stabilized by GSK3 inhibition in medium with 2i, supplies transcriptional coregulators at pluripotency loci. This selectively strengthens pluripotency loci and renders them addicted to transcription initiation for productive gene body elongation in detriment to Pol2 pause release. By contrast, cell cycle genes are not bound by β-catenin, and proliferation/self-renewal remains tightly controlled by Pol2 pause release under 2i conditions. Our findings explain how pluripotency is reinforced in the ground state and also provide a general model for transcriptional resilience/adaptation upon network perturbation in other contexts.
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Ask, Magnus, Valeria Mapelli, Heidi Höck, Lisbeth Olsson et Maurizio Bettiga. « Engineering glutathione biosynthesis of Saccharomyces cerevisiae increases robustness to inhibitors in pretreated lignocellulosic materials ». Microbial Cell Factories 12, no 1 (2013) : 87. http://dx.doi.org/10.1186/1475-2859-12-87.
Texte intégralThèses sur le sujet "Inhibitors, Robustness"
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SIGNORI, LORENZO. « Biofuels And Chemicals Production From Renewable Raw-Materials. Exploiting yeasts diversity to bridge the gap between the proof-of-concept and industrial success ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2016. http://hdl.handle.net/10281/101998.
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The success of the biorefinery concept will require efficient, robust and versatile cell factories. Currently, the major part of industrial microorganisms are used because of historical grounds, rather than being selected for a specific application. Additionally, demands for increased productivity, wider substrate range utilization, and production of nonconventional compounds lead to a great interest in further improving the currently used industrial workhorses (hosts) and the selection or development of strains with novel properties.
The model yeast Saccharomyces cerevisiae is the main microorganism used for first generation ethanol production. When moving from first to second generation of production, one of the major obstacles for a viable development is the toxic effect of compounds released during the pre-treatment of lignocellulosic biomasses, which are the more sustainable feedstock utilized.
In the first part of this work, two different approaches to improve S. cerevisiae tolerance to compounds deriving from biomass pre-treatment are described.
Firstly, the effects of overexpressing genes encoding the transcription factor (YAP1) and the mitochondrial NADH-cytochrome b5 reductase (MCR1) was evaluated in an industrial xylose-consuming S. cerevisiae strain. During batch fermentation on undiluted and undetoxified spruce hydrolysate overexpression of either genes resulted in faster hexose catabolism. The second approach revealed that acetic acid tolerance of S. cerevisiae can be increased by engineering it to endogenously produce L-ascorbic acid (L-AA).
In the second part of the work, since the currently used industrial yeasts represent only the tip of the proverbial iceberg of the genetic diversity present in nature, different non-saccharomyces yeasts were investigated for their potential industrial applications: Kluyveromyces marxianus (CBS 712), the oleaginous yeasts Rhodosporidium toruloides (DSM 4444), Lipomyces starkeyi (DSM 70295) and Cryptococcus curvatus (DSM 70022), Zygosacchromyces bailii and finally, Candida lignohabitans.
Overall, the work performed resulted in the development of industrial S. cerevisiae strains with improved traits that can match the requirements of lignocellulosic hydrolysate fermentation. The work also contributed to a better understanding of the metabolism and physiology of different non-saccharomyces yeasts with a great industrial potential.
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BERTAGNOLI, STEFANO. « Improving robustness and metabolic profile of saccharomyces cerevisiae for industrial bioprocesses ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28926.
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The fossil energy resources decrease and climate changes, caused by carbon dioxide (CO2) emissions, have led most industrialized countries to undertake policies aimed at the development and use of renewable energy sources. Among the renewable energies, vegetal biomasses play a key role because widely available and potentially able to cover up to 200% of the global energy demand. Vegetal biomasses can be used mainly as raw materials for the production of chemicals, biofuels and energy, in the increasingly important green economy concept based on biorefineries creation. Although the vegetal biomasses result widely available, rising costs of food raw material such as wheat, corn and sugar beet have raised a serious ethical problem using these resources. To avoid the use of such raw materials, the exploitation of lignocellulosic biomasses plays a fundamental role in the industry. However, for an efficient utilization of lignocellulosic biomasses, new technologies are required in order to transform the starting biomass into simple molecules, such as pentoses and hexoses sugars, more easily to use by the microrganism, which will have the task of producing both fine chemicals and bulk chemicals in an economically and environmentally sustainable processes. In this regard, industrial biotechnologies should be able to develop new microrganisms capable to face the harsh environmental conditions that occur during an industrial production process. For many of these productions the yeast Saccharomyces cerevisiae is largely used, not only because of its naturally ability to produce large ethanol amount, but also is widely known both at genetic and metabolic level, outlining a good starting point for the development of producers strains with high tolerance against different stresses occur during an industrial process. This is the view adopted by NEMO project (Novel high performance Enzymes and Microrganisms for conversion of lignocellulosic biomass to ethanol), belonging to the European Union seventh framework program, where it become of primary importance the development of microrganisms, especially S.cerevisiae, for the second generation ethanol production. Microrganisms must be, on the one hand able to efficiently utilize all the sugars released from lignocellulosic biomass pre-treatment, on the other hand should be more tolerant against process conditons, such as inhibitory compounds and environmental stresses.
A point of relevant importance is the ability to utilize pentose sugars, like D-xylose, released in large amount after lignocellulose pre-treatment. Currently, worldwide researches are focused on the development of yeast strains engineered with xylose degradation pathways involving the pentose phosphate pathway. In fact the fungal pathway exploits xylose reductase and the xylitol dehydrogenase while the bacterial pathway exploits xylose isomerase; both pathways degrade D-xylose into D-xylulose, which will enter into pentose phosphate pathway.
In addition to these two pathways studied since the ‘80s of the last century, there also two other poorly known metabolisms, described for the first time in the ‘70s, which produce alpha-ketoglutarate or pyruvate and glycolaldehyde through an oxidative xylose degradation. These pathways are composed of 5 enzymatic reactions by the Weimberg’s pathway and of 4 enzymatic reactions by the Dahms’ pathway, however they share the first 3 enzymatic reactions. After bioinformatics we were identified the presence of Weimberg’s pathway into Burkholderia xenovorans, while the reaction that characterizes the Dahms’ pathway has been identified in Escherichia coli. The encoding genes for these enzymatic activities were expressed in S.cerevisiae, and the capacity to grow on D-xylose as carbon source are evaluated. The reconstruction of these two pathways showed a poorly growth capacity on xylose. Such growth limitation seems to be related to several factors: the presence of bottlenecks associated to enzymes functionality, like D-xylonate dehydratase activity; the yeast ability to internalize xylose efficiently; the involved genes optimization.
Another important aspect is the yeast ability to face and overcome environmental stresses encountered during an industrial process. The cytoplasmic membrane plays a key role in cellular homeostasis, being at the interface between the cell and the external environment, and reacting at environmental changes. The plant membrane protein TIL gives particular strength to the yeast cells when these are subjected to environmental stresses of industrial relevance, such as the presence of oxidative agents or during temperature changes. However, when TIL is expressed in an industrial and/or in an engineered laboratory strains, for industrial use, the protective effect against prolonged stress exposure and process conditions disappear.
Finally, a further important aspect during an industrial process is the S.cerevisiae ability to tolerate the growth inhibitory compounds presence into pre-treated lignocellulose. In fact has been largely described how chemical compounds like aldehydes, organic acids and phenolic compounds, released during lignocellulose pre-treatment process, are toxic at certain concentration, inhibiting S.cerevisiae growth or causing yeast death. The growth performance of different wild type or engineered yeast strains are evaluated on spruce and giant cane lignocellulose pre-treated: in addition the same strains were tested on minimal formulated medium according to the spruce pre-treated composition. The results showed that the combination of low pH and the presence of organic acids, especially acetic acid and formic acid, are dramatically harmful for growth of both industrial strain, naturally more tolerant, and engineered strain, for the production and recycle of L-ascorbic acid. However, the behavior of engineered strain for production and recycle of L-ascorbic acid is interesting at low pH, because showed higher tolerance than other strains in terms of growth rate and ethanol production and productivity.
Despite the positive results obtained by engineering microrganisms, especially S.cerevisiae, in laboratory, their industrial uses still remain limited. Therefore, appears extremely important the construction of more robustness strains, able to withstand different environmental conditions along an entire industrial process, with consequent influence on yields, production and productivity. For these reasons, the research is aimed to combine these aspects to provide the best microrganism possible to industry productions.
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Besnard, Fabrice. « Etude du rôle de AHP6 dans le contrôle de la phyllotaxie chez la plante modèle Arabidopsis thaliana : robustesse et coordination spatio-temporelle au cours du développement de structures auto-organisées ». Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2011. http://tel.archives-ouvertes.fr/tel-00769405.
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En se développant, les plantes produisent des organes le long des tiges suivant des organisations stéréotypées, appelées phyllotaxies. Ces structures se forment dans les méristèmes, qui abritent une niche de cellules souches : les organes y sont produits successivement et leur positionnement dépendrait d'interactions dynamiques avec les organes pré-existants. Ces interactions seraient notamment dues à des champs inhibiteurs générés par le transport polaire de l'hormone végétale auxine. Afin de rechercher si d'autres facteurs que l'auxine contrôlent la phyllotaxie chez Arabidopsis thaliana, nous nous sommes intéressés au rôle possible des cytokinines, une autre hormone végétale. Nous avons développé des nouvelles méthodes statistiques pour analyser la structure de la phyllotaxie. Cette approche nous a permis d'identifier des anomalies de phyllotaxie chez des plantes mutantes pour le gène AHP6 (ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER protein 6), un inhibiteur de la signalisation des cytokinines. Notre analyse suggérait des possibles perturbations du plastochrone, la période de temps séparant l'initiation de deux organes, ce que nous avons alors confirmé par imagerie confocale en temps réel. Nos données montrent que AHP6 contrôle la régularité du plastochrone, et suggèrent que les perturbations de phyllotaxies sont dues à l'initiation simultanée de deux à trois organes dans le méristème. De plus, AHP6 est exprimé dans les organes et sa protéine établit des champs qui inhibent la signalisation des cytokinines au delà des organes. Pour mieux comprendre les rôles possibles de ces champs, nous avons généré un modèle numérique théorique de la phyllotaxie. Notre étude suggère que le plastochrone pourrait être déstabilisé par du bruit affectant le seuil d'activation nécessaire aux cellules méristématiques pour se différencier en organe. Des champs inhibiteurs pourraient filtrer les effets de ce bruit en influant sur la cinétique d'émergence des organes. Les propriétés observées des champs de AHP6 sont en accord avec ce modèle et nos données expérimentales suggèrent en effet que AHP6 et les cytokinines peuvent moduler la signalisation auxine lors de l'émergence des organes. Nous proposons comme modèle que le transport et la signalisation de l'auxine positionnent de manière robuste les organes mais génèrent un plastochrone irrégulier en présence de bruit. Des champs inhibiteurs de cytokinines stabiliseraient le plastochrone, assurant un couplage plus robuste entre le temps et l'espace lors de l'établissement de la phyllotaxie.
Chapitres de livres sur le sujet "Inhibitors, Robustness"
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Royce, Liam, et Laura R. Jarboe. « Metabolic Engineering for Biocatalyst Robustness to Organic Inhibitors ». Dans Bioprocessing Technology for Production of Biopharmaceuticals and Bioproducts, 239–65. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2018. http://dx.doi.org/10.1002/9781119378341.ch7.
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André, Étienne, Giuseppe Pellegrino et Laure Petrucci. « Precise Robustness Analysis of Time Petri Nets with Inhibitor Arcs ». Dans Lecture Notes in Computer Science, 1–15. Berlin, Heidelberg : Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-40229-6_1.
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Yamamoto, Lidia, et Daniele Miorandi. « Evaluating the Robustness of Activator-Inhibitor Models for Cluster Head Computation ». Dans Lecture Notes in Computer Science, 143–54. Berlin, Heidelberg : Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-15461-4_13.
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Shi, Haibo, Zhijie Wang, Jinli Xie et Chongbin Guo. « Robustness of Gamma-Oscillation in Networks of Excitatory and Inhibitory Neurons with Conductance-Based Synapse ». Dans Advances in Neural Networks – ISNN 2011, 10–16. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-21105-8_2.
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Sharma, R. « Sources of Active Ingredients for Sustainable Corrosion Inhibitors ». Dans Sustainable Corrosion Inhibitors, 30–45. Materials Research Forum LLC, 2021. http://dx.doi.org/10.21741/9781644901496-2.
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Metal corrosion is a grave problem, having deleterious effects on human health, the economy, the environment, and many engineering schemes, for example, automobiles, aircraft, naval vessels, and pipelines. For the confirmation of enduring reliability and stability of alloys and metals, corrosion-protective surfaces are of the greatest significance, for example, ions and water, through restraining their interactions with corrosive species. Though, their applied submissions are frequently bounded whichever through deprived mechanical robustness or else through the incapability to resist low surface tension liquids, for example, alcohols and oil. In this chapter, we have focused on diverse materials as sustainable corrosion inhibitors such as organic corrosion inhibitors, green corrosion inhibitors, and polymer-based corrosion inhibitors to protect materials from being corroded. Amongst them, we especially focus on green corrosion inhibitors as a consequence of simple manufacturing, easy availability, cost-effectiveness, and biodegradable nature.
Actes de conférences sur le sujet "Inhibitors, Robustness"
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Punase, Abhishek, Claudia Mazzeo, Ron Garan et Jonathan Wylde. « Novel In-Field Technique to Monitor and Optimize Asphaltene Inhibitor Performance : A Case Study from Gulf of Mexico ». Dans SPE Annual Technical Conference and Exhibition. SPE, 2022. http://dx.doi.org/10.2118/210278-ms.
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Abstract Asphaltene precipitation and deposition is a major flow assurance issue faced by the oil and gas industry. The complex nature and non-uniform molecular structure of asphaltenes complicates efforts to accurately assess their stability. Moreover, developing test methodologies with strong laboratory-to-field correlation presents additional challenges. The focus of this study is to discuss the successful validation and application of a novel test method for monitoring and optimizing the performance of an asphaltene inhibitor over incumbent product in a Gulf of Mexico deep-water field leading to approximately 40% reduction in operating dosage requirement. Application of a newly developed asphaltene inhibitor was performed on a deep-water field in the Gulf of Mexico region experiencing severe asphaltene deposition problems. This study evaluates the correlation between the thermo-electric properties and dispersion tendencies of asphaltenes in treated (with incumbent and new inhibitors) and untreated crude oil samples at both laboratory and field environments. The switching of inhibitor was conducted through multi-step process involving a solvent flush followed by new AI injected through the umbilical tubing. The pre-treatment and solvent flushed flow-back samples were collected, and thermo-electric values were measured to establish the base condition. Performance monitoring of the new inhibitor at various AI dosages was carried out in the field over a duration of 3 months to validate the direct laboratory-to-field relationship. Higher readings of the thermo-electric property are indicative of a better dispersion state of the polar asphaltene fraction within the test sample. Hence, the pre-treatment samples were observed to have lower thermo-electric values as compared to the flow-back samples collected after the solvent flush stage. Stabilized higher readings were recorded for the samples analyzed in the next three months and a step- down trend was observed with reduction in AI dosage to the lower optimized level. Add itionally, the amount of asphaltene that can be precipitated from the field samples were also measured and it followed an inverse relationship with the thermo-electric values, corroborating the expected asphaltene stability behavior. Furthermore, differential pressure across the flowline was also monitored for this well to confirm the absence of asphaltene deposition throughout the assessment period. A strong correlation between the laboratory and field results obtained from this thermo-electric technique and its validation with other industry standard methods highlight the reliability and high degree of accuracy of the novel method. With this study, an innovative method of assessing and monitoring the stability of asphaltenes and efficiency of an AI within the native crude oil medium is presented. The effectiveness of the technique to decipher and record variations during different stages of an asphaltene remediation job demonstrates its robustness and applicability as an efficient monitoring tool with great laboratory-to-field correlation.
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Boboriko, Natalia, He Liying et Yaraslau Dzichenka. « THE EXPLORATION OF CYP17A1 LIGAND SPACE BY THE QSAR MODEL ». Dans 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.439b.
Texte intégralRésumé :
Cytochrome P450 17A1 (CYP17A1) is a critically important enzyme in humans that catalyzes the formation of all endogenous androgens. This enzyme is often considered a molecular target for the development of novel high efficient drugs against prostate cancer. In the present work, the random forest algorithm was used to conduct a QSAR study on 370 CYP17A1 ligands with different structures that were collected from the literature and databases, and a QSAR model was created based on the five important descriptors screened out – 2D adjacency and distance matrix descriptors, 2D atom counts and bond counts and 3D surface area, volume and shape descriptors. The model was verified by the test set (accuracy, specificity, sensitivity, F-measure, MCC, and AUC were calculated). It was revealed that the hydrophobic properties of the vdW surface of the ligand have a significant contribution to the activity prediction. The hydrophobic effect of the molecules may be aroused by the presence of the hydrophobic groups or aromatic rings in the molecules. The created QSAR model shows that the molecules with more aromatic rings have better activity. The accuracy of the model on the test set was 84%, precision – 81%, sensitivity – 93%, specificity – 72%, F-measure – 0.87, MCC – 0.67, AUC – 0.88. The model has good robustness and predictive ability and can be used to screen and discover new highly active CYP17A1 inhibitors.
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Anres, Stephane, Sadia Shaiek, Fabrice Bacati, Riccardo Giolo, Walid Zid, Enrico La Sorda, Marianna Rondon et al. « How Subsea Produced Water Management Can Reduce Overall Carbon Footprint of Subsea-to-Shore Oil Developments ». Dans Offshore Technology Conference. OTC, 2022. http://dx.doi.org/10.4043/31822-ms.
Texte intégralRésumé :
Abstract A new subsea-to-shore oil field architecture is presented where produced water is separated, treated and re-injected locally. This solution reduces the overall power consumption and the global CO2e footprint of the development compared to an architecture where the whole production is sent to shore. The paper will present the results of a study for the development of a 200 000 bpd oil field requiring 300 000 bpd water injection located 150 km from shore in 1500 m water depth and with a field life of 15 years. Preliminary design work performed covers flow assurance, subsea process, subsea equipment, subsea layout as well as CO2e footprint comparison with a scenario where all the production is sent to shore. The system incorporates a gravity-based liquid-liquid separator for bulk oil-water separation, produced water is then treated, mixed with desulfated seawater and re-injected. Oil, gas and residual produced water are sent to shore via a single wet insulated line with continuous injection of low-dosage hydrate inhibitors. This scenario has two main advantages compared to a subsea-to-shore without subsea processing. The first is that the power required to boost production is significantly reduced. The second is that the volume of produced water to be treated onshore is also significantly reduced, which is advantageous, not only in terms of cost, but also in terms of reducing the shore operations’ footprint. Particular focus will be made on the produced water treatment design which is a two-stage design using two different technologies for increased robustness in order to reach a specification of 30 ppm oil-in-water for injection water.
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Yang, Xiang Y., Taiwei Lu et Francis T. S. Yu. « Generalized interpattern association neural network ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.mn6.
Texte intégralRésumé :
The interpattem-association (IPA) neuralnetwork model emphasizes the effect of the special features,1 which makes it particularly suitable for application to reference patterns that are similar to one another. To achieve robustness of the neural network, some interconnection redundancy must be introduced. The IPA algorithm proposed in our previous publication is based on logic rules that determine the excitory and inhibitory interconnection. However, the interconnections were excessively redundant, and common features were not effectively suppressed.
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Du, Zhenjiao, et Yonghui Li. « Quantitative Structure-activity Relationship Study on Antioxidant Dipeptides ». Dans 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/cpyc1755.
Texte intégralRésumé :
Antioxidative peptides have attracted increasing interest of researchers and consumers. Compared to wet chemistry methods, quantitative structure-activity relationship (QSAR) analysis as a in silicon method can be more efficient and cost effective and has been successfully applied to activity prediction of angiotensin I-converting enzyme inhibitory activity and bitterness of peptides. However, there are only few QSAR studies on antioxidative activity, particularly for dipeptides which have demonstrated ideal absorption ability in intestinal compared to larger peptides. This study aimed to conduct a comprehensive QSAR analysis between simple structure dipeptides and their antioxidative activity based on available results. 16 common amino acid descriptors were adopted and combined with partial least squares regression (PLSR) for modelling of ABTS and ORAC antioxidant activities of 75 dipeptides from literatures. Two descriptors, namely G-scale and VSW, were selected for further optimization of PLSR models for ABTS activity and ORAC activity, respectively. The two models resulted in R2 of 0.846 and 0.865 and Q2 of 0.737 and 0.756, respectively. With 20 times permutation, the R2 intercepts were 0.142 and 0.198, demonstrating the robustness of the models. Further, based on the two established models, the ABTS and ORAC activities of totally 400 dipeptides were predicted for screening. Overall, only a few descriptors can achieve acceptable performance in antioxidative activity modeling of dipeptides. The N-terminal residues have greater contribution to both ABTS and ORAC activity. Specifically, hydrophobicity played an important role in ABTS activity. The W, Y, E and L amino acid in the N-terminal of a dipeptide are likely to result in higher ABTS activity and the W and Y in the N-terminal of a dipeptide are likely to lead to higher ORAC activity. This study provides important guidance for future protein hydrolysis for antioxidant peptides, design, and selection of physicochemical properties and regression methods for model development.