Academic literature on the topic 'Chemical inhibitors'
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Journal articles on the topic "Chemical inhibitors"
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Osadchuk, T. V., O. V. Shybyryn, and V. K. Kibirev. "Chemical structure and properties of low-molecular furin inhibitors." Ukrainian Biochemical Journal 88, no. 6 (December 14, 2016): 5–25. http://dx.doi.org/10.15407/ubj88.06.005.
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Grant, Karen M., Morag H. Dunion, Vanessa Yardley, Alexios-Leandros Skaltsounis, Doris Marko, Gerhard Eisenbrand, Simon L. Croft, Laurent Meijer, and Jeremy C. Mottram. "Inhibitors of Leishmania mexicana CRK3 Cyclin-Dependent Kinase: Chemical Library Screen and Antileishmanial Activity." Antimicrobial Agents and Chemotherapy 48, no. 8 (August 2004): 3033–42. http://dx.doi.org/10.1128/aac.48.8.3033-3042.2004.
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ABSTRACT The CRK3 cyclin-dependent kinase of Leishmania has been shown by genetic manipulation of the parasite to be essential for proliferation. We present data which demonstrate that chemical inhibition of CRK3 impairs the parasite's viability within macrophages, thus further validating CRK3 as a potential drug target. A microtiter plate-based histone H1 kinase assay was developed to screen CRK3 against a chemical library enriched for protein kinase inhibitors. Twenty-seven potent CRK3 inhibitors were discovered and screened against Leishmania donovani amastigotes in vitro. Sixteen of the CRK3 inhibitors displayed antileishmanial activity, with a 50% effective dose (ED50) of less than 10 μM. These compounds fell into four chemical classes: the 2,6,9-trisubstituted purines, including the C-2-alkynylated purines; the indirubins; the paullones; and derivatives of the nonspecific kinase inhibitor staurosporine. The paullones and staurosporine derivatives were toxic to macrophages. The 2,6,9-trisubstituted purines inhibited CRK3 in vitro, with 50% inhibitory concentrations ranging from high nanomolar to low micromolar concentrations. The most potent inhibitors of CRK3 (compounds 98/516 and 97/344) belonged to the indirubin class; the 50% inhibitory concentrations for these inhibitors were 16 and 47 nM, respectively, and the ED50s for these inhibitors were 5.8 and 7.6 μM, respectively. In culture, the indirubins caused growth arrest, a change in DNA content, and aberrant cell types, all consistent with the intracellular inhibition of a cyclin-dependent kinase and disruption of cell cycle control. Thus, use of chemical inhibitors supports genetic studies to confirm CRK3 as a validated drug target in Leishmania and provides pharmacophores for further drug development.
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Kumar Dokka, Muni, Hemalatha K. P. J, and Siva Prasad Davuluri. "CHARACTERIZATION OF MONOHEADED TRYPSIN INHIBITORS FROM THE SEEDS OF ABELMOSCHUS MOSCHATUS L." Asian Journal of Pharmaceutical and Clinical Research 11, no. 12 (December 7, 2018): 459. http://dx.doi.org/10.22159/ajpcr.2018.v11i12.28735.
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Objective: The objective of the present study was to characterize the monoheaded trypsin inhibitors, Abelmoschus moschatus trypsin inhibitor-I (AMTI-I) and AMTI-II from the seeds of A. moschatus with respect to their specificity, mode of action, and active site residues.Methods: Standard methods were followed in determining inhibitory activities of monoheaded inhibitors. IC50 values and inhibitory constants (Ki) of AMTI-I and AMTI-II were determined. Studies on complex formation and chemical modification of inhibitors were performed.Results: AMTI-I and AMTI-II were found to be serpins, strongly active against trypsin, moderately active against porcine elastase, Staphylococcus aureus protease, and Aspergillus oryzae protease. AMTI-I and AMTI-II have shown non-competitive type of inhibition toward bovine trypsin with Ki values of inhibitors for trypsin found to be 0.25±0.02 nM and 0.22±0.06 nM, respectively. Complex studies revealed the formation of stable 1:1 complex of trypsin with both AMTI-I and AMTI-II. Chemical modification of the functional groups of the inhibitors by selective reagents indicated that arginine residues are essential for their trypsin inhibitory activities.Conclusion: Investigations on the specificity of protease inhibitors are important for understanding their physiological role, control mechanisms involved in the regulation of proteolysis in biological systems and mode of action.
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Li, Wenchao, Bowen Pan, Yang Shi, Meiying Wang, Tianjiao Han, Qing Wang, Guifang Duan, and Hongzheng Fu. "Identification of poly(ADP-ribose)polymerase 1 and 2 (PARP1/2) as targets of andrographolide using an integrated chemical biology approach." Chemical Communications 57, no. 51 (2021): 6308–11. http://dx.doi.org/10.1039/d1cc02272e.
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Andrographolide is the first PARP natural product inhibitor that does not contain an amide structure and has an inhibitory activity in the nanomolar range. This chemical structure is significant for expanding the structural type of PARP inhibitors.
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Sharma, Manish Kumar, Anil Kumar Sharma, and S. P. Mathur. "Solanum surrattence as Potential Corrosion Inhibitor." ISRN Corrosion 2012 (August 28, 2012): 1–5. http://dx.doi.org/10.5402/2012/907676.
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Developping chip and ecofriendlly corrosion inhibitors can replace toxic chemicals which are currently used in industries. Plant extract of Solanum surrattence in acetone, petroleum ether, and methanol has been tasted using mass loss and thermometric measurements for corrosion of aluminium in acid solutions. The plant extract of Solanum surrattence is a good corrosion inhibitor for aluminium. The inhibition efficiency depends upon the concentration of inhibitors, it inhibits the metal of 97.60% at its maximum value. This inhibitor shows efficiency at 25°C. At higher temperature the inhibition efficiency decreases. These types of inhibitors can be used to replace the toxic chemicals which are currently used in industries. We find out cheap and ecofriendlly corrosion inhibitors which can be used by acid, petrochemical, and chemical industries.
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Ernawati, Teni, Maksum Radji, Muhammad Hanafi, Abdul Mun’im, and Arry Yanuar. "Cinnamic Acid Derivatives as α-Glucosidase Inhibitor Agents." Indonesian Journal of Chemistry 17, no. 1 (April 1, 2017): 151. http://dx.doi.org/10.22146/ijc.23572.
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This paper reviews biological activity of some cinnamic acid derivative compounds which are isolated from natural materials and synthesized from the chemical compounds as an agent of α-glucosidase inhibitors for the antidiabetic drug. Aegeline, anhydroaegeline and aeglinoside B are natural products isolated compounds that have potential as an α-glucosidase inhibitor. Meanwhile, α-glucosidase inhibitor class of derivatives of cinnamic acid synthesized compounds are p-methoxy cinnamic acid and p-methoxyethyl cinnamate. Chemically, cinnamic acid has three main functional groups: first is the substitution of the phenyl group, second is the additive reaction into the α-β unsaturated, and third is the chemical reaction with carboxylic acid functional groups. The synthesis and modification of the structure of cinnamic acid are very influential in inhibitory activity against α-glucosidase.
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Juárez-Mercado, K. Eurídice, Fernando D. Prieto-Martínez, Norberto Sánchez-Cruz, Andrea Peña-Castillo, Diego Prada-Gracia, and José L. Medina-Franco. "Expanding the Structural Diversity of DNA Methyltransferase Inhibitors." Pharmaceuticals 14, no. 1 (December 27, 2020): 17. http://dx.doi.org/10.3390/ph14010017.
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Inhibitors of DNA methyltransferases (DNMTs) are attractive compounds for epigenetic drug discovery. They are also chemical tools to understand the biochemistry of epigenetic processes. Herein, we report five distinct inhibitors of DNMT1 characterized in enzymatic inhibition assays that did not show activity with DNMT3B. It was concluded that the dietary component theaflavin is an inhibitor of DNMT1. Two additional novel inhibitors of DNMT1 are the approved drugs glyburide and panobinostat. The DNMT1 enzymatic inhibitory activity of panobinostat, a known pan inhibitor of histone deacetylases, agrees with experimental reports of its ability to reduce DNMT1 activity in liver cancer cell lines. Molecular docking of the active compounds with DNMT1, and re-scoring with the recently developed extended connectivity interaction features approach, led to an excellent agreement between the experimental IC50 values and docking scores.
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Umezawa, Koji, and Isao Kii. "Druggable Transient Pockets in Protein Kinases." Molecules 26, no. 3 (January 27, 2021): 651. http://dx.doi.org/10.3390/molecules26030651.
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Drug discovery using small molecule inhibitors is reaching a stalemate due to low selectivity, adverse off-target effects and inevitable failures in clinical trials. Conventional chemical screening methods may miss potent small molecules because of their use of simple but outdated kits composed of recombinant enzyme proteins. Non-canonical inhibitors targeting a hidden pocket in a protein have received considerable research attention. Kii and colleagues identified an inhibitor targeting a transient pocket in the kinase DYRK1A during its folding process and termed it FINDY. FINDY exhibits a unique inhibitory profile; that is, FINDY does not inhibit the fully folded form of DYRK1A, indicating that the FINDY-binding pocket is hidden in the folded form. This intriguing pocket opens during the folding process and then closes upon completion of folding. In this review, we discuss previously established kinase inhibitors and their inhibitory mechanisms in comparison with FINDY. We also compare the inhibitory mechanisms with the growing concept of “cryptic inhibitor-binding sites.” These sites are buried on the inhibitor-unbound surface but become apparent when the inhibitor is bound. In addition, an alternative method based on cell-free protein synthesis of protein kinases may allow the discovery of small molecules that occupy these mysterious binding sites. Transitional folding intermediates would become alternative targets in drug discovery, enabling the efficient development of potent kinase inhibitors.
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Mohyaldinn, Mysara Eissa, Wai Lin, Ola Gawi, Mokhtar Che Ismail, Quosay A. Ahmed, Mohammed A. Ayoub, and Anas Hasan. "Experimental Investigation of a New Derived Oleochemical Corrosion Inhibitor." Key Engineering Materials 796 (March 2019): 112–20. http://dx.doi.org/10.4028/www.scientific.net/kem.796.112.
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Most of the corrosion inhibitors that are used in industry contain chemicals that are harmful to health and environment. Corrosion inhibitors derived from green sources are, therefore, believed to be a good option for replacing the chemical corrosion inhibitors. In this work, a green oleochemical corrosion inhibitor derived from Jatropha Curcas is introduced. The paper discusses the methodology of deriving the corrosion inhibitor as well as the experimental test conducted for evaluating its corrosion inhibition efficiency. The new oleochemical corrosion inhibitor was derived via two reactions. Jatropha oil was firstly saponified with sodium hydroxide to yield gras acid and glycerol, which was then esterified with boron fluoride in presence of excess methanol to produce the oil methyl esters, which is used as oleo-chemical corrosion inhibitor. To evaluate the oleo-chemical corrosion inhibitor, the corrosion rate of mild steel in NaCl corrosive medium with CO2 is tested at static condition and two dynamic conditions, namely 500 and 1500 rpm. This is to simulate the transitional and turbulent flow in a pipeline. At each dynamic condition, the proposed corrosion inhibitor was tested at concentration dosages of 0, 50, 100, and 150 ppm. The experiments results revealed a good performance of the new oleochemical corrosion inhibitor. The inhibition efficiency was found to be highly affected by the concentration of corrosion inhibitor. Total corrosion inhibition of the mild steel was noticed by using 150 ppm at dynamic condition of 500 rpm.
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Nasser, Rabab M., and Nora M. Masmali. "The effectiveness of Tamarindus Indica extracts as a metal corrosion inhibitor in various circumstances." Anti-Corrosion Methods and Materials 69, no. 3 (March 3, 2022): 224–33. http://dx.doi.org/10.1108/acmm-06-2021-2490.
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Purpose Plant development and use as green corrosion inhibitors are already recognized as one of the most environmentally friendly and effective protocols. In recent years, efforts have been made to find green corrosion inhibitors as an alternative to synthetic inhibitors for metals in acid medium. This paper aims to report the investigation of use of aqueous extracts of Tamarindus Indica as green inhibitors for corrosion of metals within different circumstances. Design/methodology/approach The use of Tamarindus Indica extracts (leaves, stem, fruit pulp and fruit husk) as corrosion inhibitors for mild steel and aluminum in different mediums (HCl, H2SO4, formic acid and citric acid) at different temperatures was investigated. Findings The inhibitory efficiency of Tamarindus Indica extracts increases with increasing concentration and decreases with increasing temperature. Langmuir is the adsorption isotherm, and the extract (inhibitor) is a mixed-type inhibitor (physisorption and chemisorption). Practical implications Tamarindus extracts (leaves, stem, fruit pulp and fruit husk) are effective inhibitors and can be used to protect metals from corrosion at different circumstances. Originality/value To the best of the authors’ knowledge, this is the first review that discusses the use of Tamarindus Indica extracts as corrosion inhibitors for metals.
Dissertations / Theses on the topic "Chemical inhibitors"
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Thornton, Stephen S. "Design, synthesis, and kinetics of novel acetylcholinesterase inhibitors." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/26964.
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Matheson, Christopher. "Chemical and biological studies with Nek2 kinase inhibitors." Thesis, University of Newcastle upon Tyne, 2012. http://hdl.handle.net/10443/2024.
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The aim of modern cancer chemotherapy is to develop targeted drugs designed to exploit pharmacological differences between tumour cells and healthy tissues. One focus of this effort has been the identification of protein kinases that are expressed at elevated levels or in mutated forms, indicating a reliance of the tumour on specific kinase function. Nek2 is a human serine/threonine protein kinase related to the fungal protein NIMA, a critical mediator of mitosis. Interestingly, Nek2 is found to be upregulated in a variety of tumour cell lines derived from breast, cervical and prostate carcinomas, as well as lymphomas. Human Nek2 is implicated in the regulation of the centrosome and formation of a bipolar spindle, a framework that is vital for correct separation of sister chromatids during mitosis. It is proposed that Nek2 may complex with, and phosphorylate, proteins accumulated at the centrosome, possibly playing a role in intercentriolar linker cleavage during the centrosome cycle. Abnormalities in centrosome number and function are common in many cancers, indicating that loss of centrosome cycle regulation may be a major contributing factor in tumour progression. Overexpression of Nek2 may result in premature centrosome disjunction, and deregulation of this tightly controlled mitotic machinery leads to chromatid segregation errors, aneuploidy and chromosomal instability, common genetic abnormalities observed in tumour cells. This indicates a role for abnormal Nek2 function in tumourigenesis, and Nek2 depletion in a number of tumour cell lines has been shown to cause growth suppression and apoptosis. Nek2 is thus a potentially attractive cancer therapeutic target for small-molecule kinase inhibitors. Previous studies identified substituted purine derivatives as modest inhibitors of Nek2, leading to the discovery of two distinct inhibitor classes, exhibiting ATP-competitive and irreversible inhibition of the kinase, respectively. Purine-based compounds bearing substituents at the 8-position have emerged as modest competitive inhibitors of Nek2 that occupy the kinase ATP-domain through an unusual binding orientation (45; IC = 51.8 M). Additional possible interactions within the ATP- 50 binding site available to inhibitors of this class were explored, with the objective of developing tight-binding type II reversible inhibitors of Nek2. Structure-activity relationship studies resulted in a 10-fold improvement in activity over the initial hit compounds and a substantial improvement in drug-like properties (e.g. 129; IC = 5.1 M)). However, all 50 efforts to improve the potency of this series were unsuccessful. 6-Ethynylpurines have been identified as irreversible inhibitors of Nek2 through covalent modification of an active-site cysteine residue. The initial hit compound (147; IC = 0.14 50 M) was found to be a potent and selective inhibitor of the kinase in vitro, but with poor cellular activity attributed to limited permeability. Extensive structural modification of the 2- arylamino side-chain of this series afforded cell permeable analogues with improved potency, both in vitro and in vivo (e.g. 177; IC = 0.062 ± 0.01 M). 50 Biochemical studies using 177 suggested that inhibition of Nek2 resulted in an increase in mitotic abnormalities and a delay in mitotic progression, despite poor cellular growth inhibition being observed in initial tumour cell lines. Further cellular growth inhibition and cytotoxicity studies with selected compounds identified several sensitive tumour cell lines. However, kinase-inactive control compounds essentially devoid of Nek-inhibitory activity (e.g. 425; IC > 100 M) retained growth-inhibitory activity, indicating an alternative locus 50 of activity for the 6-ethynylpurine chemotype.
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Wong, Lai Hong. "Chemical genetic screen for inhibitors of human telomerase." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/9524.
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There remains a pressing need for the development of effective drugs that meet the clinical needs for cancer treatment, and inhibition of telomere length maintenance by disrupting human telomerase is a proven and tractable target for suppression of cancer cell growth. In response to the lack of currently available small molecules with efficacy against human telomerase, we developed a genetically and chemically tractable cell-based system in which S. cerevisiae is used to streamline the search for novel human telomerase inhibitors. Our results confirmed that yeast cell growth was rapidly inhibited upon induction of functional human telomerase at the telomere. This inducible growth arrest was used as a read-out for a high-throughput chemical screen for human telomerase inhibitors based on their ability to restore growth in the yeast system. From a library consisting of small, bioactive and cell-permeable compounds of diverse structure, we identified three novel “drug-like” compounds that inhibited the activity of native and recombinant telomerase complexes in vitro. “Validation assays” also confirmed the novel inhibitors were free of uncharacterized adverse effects against yeast and human cell models, thus confirming the specificity of these novel inhibitors against human telomerase target. This surrogate yeast model has therefore proven to be a cost-effective alternative to accelerate the search for human telomerase inhibitors, which we hope will serve to streamline the identification of further lead compounds effective against human cancer.
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Shirazi, Mehdi. "Surface application of yellowing inhibitors into paper." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38281.
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Papermakers are highly interested in upgrading mechanical paper by retarding or inhibiting the lignin color reversion. Yellowing can be prevented by screening UV light on the surface and adding yellowing inhibitors into papers. Surface treatment of paper in a size press by an inhibitor-starch mixture has more advantages compared to other methods. A novel microscopy technique using scanning electron microscopy is developed to identify and measure the polymer penetration into sized sheets.The kinetics of starch adsorption on wood fibers was elucidated. An initial high adsorption of cationic starch on pulp fibers is off set by high desorption rates. Furthermore the adsorption of hydroxyethyl ether starch increases smoothly with time due to polymer penetration into the macropores. At high salt concentrations, cationic starch does not make strong bonds with negatively charged fibers and as a result the desorption rate increases and the maximum adsorption approaches zero. The presence of salt has little effect on the adsorption of non-ionic hydroxyethyl ether starch.
Preferential adsorption of amyIose compared to amylopectin on cellulosic fibers is related to the size exclusion mechanism involved in polymer penetration into macropores.
The presence of cationic starch clusters is confirmed. The clusters initially adsorb on the fiber surface; however due to a higher desorption rate they are gradually replaced by individual polymers. The cluster size decreases with increasing shear in the presence of salt in cationic starch solutions. The cluster desorption rate for pulp fibers is higher than that for glass substrates. This might be due to different surface chemistry or roughness between pulp fibers and glass substrates. The maximum adsorption on glass substrates increases by increasing the cluster size. Hydroxyethyl ether starch does not form clusters and shear and the presence of salt have a minor effect on the polymer size.
Starch pickup by paper during surface sizing depends on the liquid absorption at the puddle and counter pressure of the trapped air in the pores. Starch viscosity, paper velocity and nip load have no effect on the thickness of the starch layer across the sized paper. However, for thick boards penetration increases by increasing the nip load due to lower sheet thickness at higher nip load. For sized board, the starch penetration is less for cationic starch than for hydroxyethyl ether starch due to higher viscosity and adsorption.
For the sized sheets with yellowing inhibitor/starch mixtures, the paper brightness after aging is affected by inhibitor concentration in the solution, since operating conditions have little effect on pickup. Using cationic starch slightly increases the brightness for boards, while it has little effect on paper brightness.
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Starks, Kenneth Maurice. "Novel pyridinium salts which inhibit acetylcholinesterase." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/26950.
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Wilson, Jeanne E. "Deacylation rates of ortho-substituted derivatives of acylated HL elastase and PP elastase : electronically or sterically dependent." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/27051.
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Corredor, Sánchez Miriam. "Chemical Modulation of Identified Hit Compounds as Apoptosis Inhibitors." Doctoral thesis, Universitat Ramon Llull, 2013. http://hdl.handle.net/10803/117361.
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L’apoptosi és un procés biològic rellevant en moltes malalties. Un punt de regulació d’aquest procés és la formació d’un complex multiproteic anomenat apoptosoma; per tant, aquest complex té un gran interès per al desenvolupament de moduladors apoptòtics. El nostre grup ha descrit prèviament una piperazina-2,5-diona substituïda en posició 3 com a potent modulador apoptòtic. Estudis estructurals d’aquest compost han permès veure la presència dels isòmers cis / trans de l’enllaç de l’amida terciària exocíclica en un procés d’intercanvi lent, fet que pot ser important per a la interacció amb la diana biològica. Aquesta informació ens va animar a mimetitzar aquests isòmers a través d’una substitució isostèrica de l’enllaç amida amb unitats de 1,2,3-triazoles. La síntesi d’aquests anàlegs restringits es va dur a terme utilitzant una reacció Ugi multicomponent seguida d’una ciclació intramolecular. L’anàlisi completa per RMN (incloent les correlacions 1H-15N en abundància natural) d’aquests compostos han permès la caracterització inequívoca dels patrons de substitució corresponents. Finalment, l’increment de l’activitat inhibitòria d’aquests nous compostos en comparació amb el compost de partida ha proporcionat nova informació sobre la unió dels compostos a la diana terapèutica i ha fet possible la identificació de nous moduladors. Cal destacar que per a una de les estructures proposades, es va formar inesperadament una β-lactama que va resultar el compost amb una activitat inhibidora més alta. Els estudis computacionals realitzats també donen suport a la hipòtesi que el mecanisme d’inhibició de tots aquests nous derivats és a través de la unió amb la proteïna Apaf-1.
Degut a la formació d’aquest cicle, es va realitzar un estudi de reactivitat per explicar la manera de ciclació dels adductes de la reacció de Ugi. Per tal de modular aquesta reacció, s’ha sintetitzat una quimioteca de compostos que contenen els dos nuclis (β-lactama o dicetopiperazina) havent-se assajat les seves activitats com a inhibidores de l’apoptosis.
Finalment, per intentar millorar les propietats dels nostres compostos com a possibles candidats a fàrmac, s’han dut a terme uns acoblaments amb alguns dels inhibidors i glicodendrímers.
Com a conclusió, s’ha sintetitzat una nova família d’inhibidors de l’apoptosi amb una llibertat conformacional menor aconseguint mantenir valors d’activitat similars. Es confia que aquests compostos mostrin una selectivitat més gran, condició fonamental per regular un procés tan delicat.La apoptosis es un proceso biológico relevante en muchas enfermedades. Uno de los puntos de regulación de este proceso es la formación del complejo multiproteico llamado apoptosoma; por tanto, este complejo reviste gran interés para el desarrollo de moduladores apoptóticos. Previamente en nuestro grupo se ha descrito una piperazina-2,5-diona sustituida en posición 3 como potente inhibidor apoptótico. Estudios estructurales de este compuesto han permitido determinar la presencia de isómeros cis / trans del enlace de la amida terciaria exocíclica en un proceso de intercambio lento, hecho que puede ser importante en la interacción con la diana biológica. Ésta información nos animó a mimetizar éstos isómeros a través de una sustitución isostérica del enlace amida con unidades 1,2,3-triazólicas. La síntesis de éstos análogos restringidos se llevó a cabo usando una reacción Ugi multicomponente seguida de una ciclación intramolecular. El análisis completo por RMN (incluyendo las correlaciones 1H-15N en abundancia natural) de estos compuestos ha permitido la caracterización inequívoca de los patrones de sustitución correspondientes. Además, el aumento de la actividad inhibitoria de los nuevos compuestos ha proporcionado nueva información sobre el tipo de interacción de los compuestos con la diana terapéutica. La formación inesperada de una β-lactama en lugar de la dicetopiperazina para una de las estructuras propuestas y el hecho que este último compuesto fuera el que mostrara mayor actividad inhibidora, fueron hechos muy interesantes que dieron lugar a estudiar en mayor profundidad la reacción de ciclación intramolecular. Se realizó un estudio de la reactividad para explicar la ciclación de los aductos de la reacción de Ugi y para modular esta reacción, se sintetizó una quimioteca con los dos tipos de ciclo (β-lactama y dicetopiperazina), habiéndose ensayado sus actividades como inhibidores de la apoptosis. Finalmente, para intentar mejorar las propiedades de nuestros compuestos como posibles candidatos a fármaco, se llevaron a cabo acoplamientos entre algunos inhibidores y diferentes tipos de glicodendrímeros. Como conclusión, se ha sintetizado una nueva familia de inhibidores de la apoptosis con una libertad conformacional menor consiguiendo mantener valores de actividad similares. Se confía que estos compuestos muestren una selectividad mayor, condición fundamental para regular un proceso tan delicado.
Apoptosis is a biological process relevant to different human diseases stated that is regulated through protein-protein interactions and complex formation. In this context, one point of regulation is the formation of the multiprotein complex known as apoptosome. Consequently, this complex is of interest for the development of apoptosis modulators. In our group, it has been previously reported a peptidomimetic compound bearing a 3-substituted-piperazine-2,5-dione moiety as a potent apoptotic inhibitor. Structural studies of this compound showed the presence of cis/trans isomers of the exocyclic tertiary amide bond in slow exchange, which should be of high relevance for off-target interaction in front of the biological target. This information encouraged us to perform an isosteric replacement of the amide bond by a 1,2,3-triazole moiety, where different substitution patterns would mimic different amide rotamers. The syntheses of these restricted analogs have been carried out using the Ugi multicomponent reaction followed by an intramolecular cyclization. Unexpectedly, for one of the proposed structures, a novel β-lactam compound was formed. All synthesized compounds showed to efficiently inhibit apoptosis, in vitro and in cellular extracts, with slight differences for the corresponding regioisomers. Noticeably, the compound bearing the new β-lactam scaffold showed the highest inhibitory activity. On the other hand, computational studies also support the hypothesis that these new families of inhibitors exert their action by binding to Apaf-1, one of the components of the apoptosome complex. Due to the formation of the unexpected β-lactam scaffold, a reactivity study has been carried out to explain the course of the intramolecular cyclization of the Ugi adducts. In order to be able to modulate this cyclization, a small library of compounds bearing both heterocyclic scaffolds has been synthesized and their activities as apoptosis inhibitors have been evaluated. Moreover, couplings between some of the apoptosome inhibitors and different glycodendrimer moieties have been carried out to improve the properties of our compounds as drug candidates. As a conclusion, a new family of compounds has been designed, synthesized and characterized, and most of them showed good apoptosis inhibitory activities in vitro and in cellular extracts. We deem that the reduction of the conformational freedom achieved in this new family of inhibitors could be fundamental to increase the selectivity, which is a highly important condition when regulating such a delicate process.
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Mayhew, Maxine Eleanor. "Chemical inhibitors for biomass yield reduction in activated sludge." Thesis, Cranfield University, 1999. http://dspace.lib.cranfield.ac.uk/handle/1826/4547.
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Increasing legislation and rising treatment and disposal costs have promoted optimisation of the activated sludge process to encompass reduction of waste biomass. Manipulation of process control such as increasing sludge age and decreasing food to microorganism ratio can lower waste sludge production, but capital works as well as increased operating costs in the form of power requirement for oxygen supply may be required. The need for a cost effective method of biomass reduction without capital expenditure has prompted research into methods beyond process control. The use of chemicals capable of disrupting microorganism metabolic pathways can theoretically allow continuation of catabolic (degradative) paths whilst halting some or all of the anabolic (growth) pathways. This project explored the use of metabolic inhibitors (uncouplers, tricarboxylic acid cycle inhibitors and antibiotics) to reduce the yield of the activated sludge process. Initial respirometric studies identified many chemicals capable of interacting with the activated sludge microorganisms. Increased oxygen uptake rate was taken as an indication of a good uncoupler, and tests highlighted 4 chemicals with significant potential for achieving biomass reduction (trypan blue, rotenone, 2,4 DNP and 4 NP). These chemicals were then tested at a laboratory scale and at bench scale in both batch and continuous simulations. Simulations were carried out using activated sludge and settled sewage feed to obtain as realistic conditions as possible. In batch tests, trypan blue, rotenone and 2,4 DNP successfully reduced mixed liquor suspended solids accumulation with little effect on COD removal compared to controls. In continuous simulations, 2,4 DNP and 4 NP both lowered yield with respect to their relative controls. Rotenone addition did not result in lowered yield. In all cases, any yield reduction was not at the expense of process efficiency in terms of COD and BOD removal. At pilot scale, 2,4 DNP almost halved the observed yield compared to the control whilst having no significant effect on BOD, COD or ammonia removal, nitrite and nitrate production, SVI or CST. Addition of chemical uncouplers had little effect on the species diversity of the activated sludge though a reduction in the floc size was observed in treated samples. Selection of a suitable chemical can result in reduced yield without detrimental effect to process efficiency in the activated sludge process. An increase in oxygen consumption occurred which has an associated cost implication, but this was not found to be significant compared to the savings made by reducing the yield.
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Zhou, Linna. "Chemical biology studies on 5-nitrofurans and sirtuin inhibitors." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3407.
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Part I: Target identification studies are one of the most difficult but rewarding challenges in chemical biology. Part I of this thesis describes target identification studies for 5-nitrofuran containing hits. The 5-nitrofurans used in this study were identified in a phenotypic screen for compounds that induced melanocyte cells death in zebrafish. Chapter 1 provides brief overviews on three related areas of the project: 1) the use of zebrafish as a model organism in drug discovery; 2) phenotypic screening using zebrafish and 3) the strategies used in target identification studies. Chapter 2 describes the synthesis of and SAR studies on two series of 5-nitrofuran containing analogues. The design and preparation of biotinylated chemical probes based on the SAR data is also described. These chemical tools are then used in affinity chromatography studies and genetic validation of a potential target (zebrafish Aldh2) of the 5-nitrofuran compounds is reported. Chapter 3 provides a review of the biological and chemical processes that human ALDHs are known to mediate. In addition, small molecules that modulate ALDH2 activity are reviewed. A detailed study of the interaction between 5-nitrofurans and human ALDH2 including in vitro enzymatic assays is described leading to the conclusion that the 5- nitrofurans under study are substrates of human ALDH2. Further mechanism of action investigations using model reactions are also presented. Chapter 4 introduces the use of 5-nitrofuran containing drugs in the clinic and highlights the reported side-effects. Further investigation of the interaction between ALDH2 and 5- nitrofurans in zebrafish and yeast using ALDH2 inhibitors is described. Based on these results, a combination therapy strategy is proposed. Finally, the trypanocidal activity of the newly synthesised 5-nitrofurans is discussed. Experimental details and future work for Part I are presented in Chapters 5 and 6 respectively. Part II: Human sirtuins are associated with various biological functions and diseases, including cancer and neurodegeneration. Previous work from the Westwood Lab has led to the discovery of the tenovins that act as inhibitors of SIRT1 and SIRT2. Part II of the thesis reports the development of potent fixed ring tenovin analogues with high SIRT2 selectivity. Chapter 7 provides a brief review of the biology of human SIRT2 and the reported SIRT2 inhibitors available to date. This is followed by a short summary of the previous work on the tenovins in the Westwood Lab and the design of the fixed ring tenovin analogues. Chapter 8 describes the synthesis of three series of fixed ring tenovin analogues. SAR data is generated based on in vitro enzymatic assays against both SIRT1 and SIRT2 and the prepared analogues showed relatively high potency and selectivity against SIRT2. Further cell-based deacetylation assay are also discussed. All the experimental details are reported in Chapter 9 and Chapter 10 provides with conclusions and proposed future work.
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Fraser, Rebecca Dawn. "Isolation of natural product inhibitors and synthesis of inhibitors of signal transduction : Part II structure-activity relationship for a series of glycosidase inhibitors." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/30508.
Full textBooks on the topic "Chemical inhibitors"
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Iqbal, Choudhary Muhammad, ed. Biological inhibitors. Amsterdam: Harwood Academic Publishers, 1996.
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Hayes, Teresa L. Corrosion inhibitors. Cleveland, Ohio: Freedonia Group, 2002.
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Baumgartner, William G. Corrosion inhibitors. Cleveland, Ohio: Freedonia Group, 1997.
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Innes, George L. Corrosion inhibitors. Norwalk, CT: Business Communications Co., 1999.
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Irene, Ash, ed. Handbook of corrosion inhibitors. 2nd ed. Endicott, N.Y: Synapse Information Resources, 2011.
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Bacanovic, Alicia. Chemical design of inhibitors of ERK1/2 dephosphorylation. Sudbury, Ont: Laurentian University, 2006.
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Evans, K. B. Summary of JAYGO mixing and FSM-1 application of castable inhibitor and liner: Final report. Brigham City, UT: Thiokol Corporation, Space Operations, 1990.
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Dicke, Marcel. Infochemicals in tritrophic interactions: Origin and function in a system consisting of predatory mites, phytophagous mites and their host plants. [S.l: s.n., 1988.
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Kovtun, G. A. Metallokompleksnye ingibitory okislenii͡a︡. Kiev: Nauk. dumka, 1993.
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Carlsson, Åse. Detection of inhibitory substances in milk. Uppsala: Swedish University of Agricultural Sciences, Department of Food Science, 1991.
Find full textBook chapters on the topic "Chemical inhibitors"
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Bartlett, Paul A. "Design of Enzyme Inhibitors." In Chemical Synthesis, 137–73. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0255-8_6.
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Lundblad, Roger L. "Inhibitors of Thrombin." In The Chemical Biology of Thrombin, 223–65. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/b22204-8.
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Teicher, Beverly A. "Topoisomerase I Inhibitors: Chemical Biology." In Cancer Drug Discovery and Development, 185–210. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-0323-4_10.
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Rogojina, Anna, Stefan Gajewski, Karim Bahmed, Neil Osheroff, and John L. Nitiss. "Topoisomerase II Inhibitors: Chemical Biology." In Cancer Drug Discovery and Development, 211–43. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-0323-4_11.
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Che, Jianwei, Yi Liu, and Nathanael S. Gray. "Design and Selection of Small Molecule Inhibitors." In Chemical Biology, 41–63. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118435762.ch3.
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Meijer, Laurent. "Chemical inhibitors of cyclin-dependent kinases." In Progress in Cell Cycle Research, 351–63. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1809-9_29.
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Adesunloye, Bamidele A., Fatima H. Karzai, and William L. Dahut. "Angiogenesis Inhibitors in the Treatment of Prostate Cancer." In Chemical Immunology and Allergy, 197–215. Basel: S. KARGER AG, 2013. http://dx.doi.org/10.1159/000353255.
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Alvira, Daniel, and Laura Mondragón. "Drug Delivery Strategies of Chemical CDK Inhibitors." In Methods in Molecular Biology, 141–54. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-2926-9_12.
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Okubo-Kurihara, Emiko, Wen-Dee Ong, Yukio Kurihara, Natsumaro Kutsuna, and Minami Matsui. "Method for Phenotypic Chemical to Identify Inhibitors." In Methods in Molecular Biology, 17–27. New York, NY: Springer US, 2020. http://dx.doi.org/10.1007/978-1-0716-0954-5_2.
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Furrer, Julien, Gregory S. Smith, and Bruno Therrien. "Metal Complexes as Enzyme Inhibitors and Catalysts in Living Cells." In Inorganic Chemical Biology, 341–71. Chichester, UK: John Wiley & Sons, Ltd, 2014. http://dx.doi.org/10.1002/9781118682975.ch11.
Full textConference papers on the topic "Chemical inhibitors"
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Løge, Isaac A., Benaiah U. Anabaraonye, and Philip L. Fosbøl. "Characterizing the Effect of Scale Inhibitors on Surfaces." In SPE International Conference on Oilfield Chemistry. SPE, 2023. http://dx.doi.org/10.2118/213830-ms.
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Abstract Inorganic scaling imposes a significant economic burden on the oil industry. Scale management protocols typically involve the use of chemical inhibitors. Most traditional methods of investigating scale formation and inhibitor performance do not provide insights into the exact mechanisms at play. However, understanding these mechanisms is critical to designing optimal mitigation interventions. We investigate BaSO4 scale formation in flow and batch experiments in the presence of a commercial inhibitor. For the first time, we apply sensitive texture parameters to characterize scale formation in the presence of chemical inhibitors. We analyzed effluent concentrations in the bulk phase using an inductively coupled plasma (ICP) technique, performed high-resolution X-ray CT scans of the surface deposits, and applied scanning electron microscopy (SEM) imaging. We used advanced image analysis to characterize how chemical inhibitors affect the overall deposition rate. We show the impact of time and inhibitor concentrations on corrosion processes.
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Beretz, A., F. Lanza, A. Stierlé, and J.-P. Cazenave. "CYCLIC NUCLEOTIDE PHOSPHODIESTERASE INHIBITORS PREVENT AGGREGATION AND SECRETION OF HUMAN PLATELETS BY RAISING CYCLIC AMP AND REDUCING CYTOPLASMIC FREE CALCIUM MOBILIZATION." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643586.
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Drugs that raise platelet cyclic AMP (cAMP) are potent inhibitors of platelet activation. We have studied the effects of 5 inhibitors of cyclic nucleotide phosphodiesterase (PDE) of different chemical structures (quercetin, Ro 15-2041, HL-725, cilostamide and MY-5445), which are all potent inhibitors of platelet function. The concentrations that inhibit by 50 % crude cAMP-PDE activity (IC50) from human platelets are: 0.06 μM(HL-725), 0.15 μM(Ro 15-2041 ), 0.23 μM(cilostamide), 6.9 μM(MY-5445) and 44.4 μM(quercetin). We measured on the same preparation of washed human platelets loaded with quin2, the aggregation and the increase in intracellular Ca2+ ([Ca2+]i) induced by 5 μM ADP alone or in the presence of PDE inhibitors.PGE1 (2 nM) potentiates significantly (1.6 to 3.3 fold) the inhibitory effects of PDE inhibitors on [Ca2+]i rises and platelet aggregation. Adrenaline, an inhibitor of adenylate cylase, prevents the effect of PDE inhibitors on ADP-induced [Ca2+]i rise and platelet aggregation. These results suggest that these compounds inhibit [Ca2+]i mobilization and subsequent ADP-induced aggregation through a rise in cAMP, because both effects are potentiated by PGE1 and inhibited by adrenaline. The inhibitor concentrations which potentiate the action of PGE1, on [ Ca2+]i levels also potentiate the rise in platelet cAMP induced by PGE-<. These results suggest that PDE inhibitors inhibit platelet aggregation Ly raising cAMP levels and subsequently inhibiting [Ca2+]i mobilization.
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Obeyesekere, Nihal U., and Jonathan J. Wylde. "Development of New Corrosion Inhibitors Using Robotics with High Throughput Experimentation Methods." In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207336-ms.
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Abstract Critical micelle concentration (CMC) is a known indicator for surfactants such as corrosion inhibitors ability to partition from two phase systems such as oil and water. Most corrosion inhibitors are surface active and at critical micelle concentration, the chemical is partitioned to water, physadsorb on metallic surfaces and form a physical barrier between steel and water. This protective barrier thus prevents corrosion from taking place on the metal surface When the applied chemical concentration is equal or higher than the CMC, the chemical is available in aqueous phase, thus preventing corrosion. Therefore, it was suggested that CMC can be used as an indicator of optimal chemical dose for corrosion control1. The lower the CMC of a corrosion inhibitor product, the better is this chemical for corrosion control as the availability of the chemical in the aqueous phase increase and therefore, can achieve corrosion control with less amount of chemical. In this work, this physical property (CMC) was used as an indicator to differentiate corrosion inhibitor performance. The corrosion inhibitor formulations were built out by using combinatorial chemical methods and the arrays of chemical formulations were screened by utilizing high throughput robotics 2-4, using CMC as the selection guide. To validate the concept, several known corrosion inhibitor formulas were selected to optimize their efficacy. Each formula contained several active ingredients and a solvent package. These raw materials were blended in random but in a control, manner using combinatorial methodologies. Instead of rapidly blending a large number of formulations using robotics, the design of control (DOE) methods were utilized to constrain the number of blends. Once the formulations were generated by DOE method, using Design Expert software that can effectively explore a desired space. The development of an equally robust prescreening analysis was also developed. This was done by using the measurements of CMC with a high-throughput screening methodology. After formulation of a vast array of formulation by using Design Expert software, the products were screened for by CMC using automated surface tension workstation. Several formulations with lower CMC than the reference products were selected. The selected corrosion inhibitor formulations were identified and blended in larger scales. The efficacy of these products was tested by classical laboratory testing methods such as rotating cylinder electrode (RCE) and rotating cage autoclave (RCA) to determine their performance as anti-corrosion agents. These tests were performed against the original reference corrosion inhibitor. The testing indicated that several corrosion inhibitor formulations outperform the original blend thus validating the proof of concept.
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Weghorn, S. J., and D. W. Stegmann. "Enhancing Chemical Efficiency Using Slow-Release Corrosion Inhibitors." In SPE International Symposium on Oilfield Chemistry. Society of Petroleum Engineers, 2005. http://dx.doi.org/10.2118/93169-ms.
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Da Silva de Aguiar, Janaina Izabel, Amir Mahmoudkhani, and Samal Ibragimova. "Ultra-Low Dose Asphaltene Inhibitors for Offshore Applications: Myth or Reality." In SPE International Conference on Oilfield Chemistry. SPE, 2021. http://dx.doi.org/10.2118/204357-ms.
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Abstract In recent years, long-distance subsea tiebacks have become a preferred field development option for deep and ultra-deepwater production. However, conditions such as lengthy umbilical systems, high pressures and variable temperatures conditions pose challenges for the continuous injection of various flow assurance chemicals. Severe operating conditions often require relatively high volumes of diluted inhibitors to be stored and injected offshore, resulting in high CAPEX costs for the installation of large topsides chemical storage tanks and their associated weight increases. Alliance Engineering estimates a deepwater platform's topsides installed costs are within the range of $35,000-$50,000/ton. It is possible to achieve significant capital cost savings on new platform designs if the dosage rates and subsequently offshore storage volumes of the highest usage production chemicals such as asphaltene inhibitors could be significantly reduced. This paper presents information on a new class of biosurfactants that are bio-based and eco-acceptable with potentials for development of ultra-low dose asphaltene inhibitors for offshore applications. Asphaltenes were extracted from chemical free crude oil samples and a curve of solubility with different ratios of heptane was obtained for each sample in order to determine the best conditions to perform the screening tests. A new class of glycolipid biosurfactants (GLP-U) was developed as an asphaltene dispersants effective at low concentrations for use in offshore applications. The new GLP-U biosurfactants are eco-acceptable and soluble in the organic solvents commonly used in offshore production chemicals. GLP-U were proved to be effective in dispersing and preventing precipitation of isolated asphaltenes at dosage rates as low as 25 mg/L (active substance), while for comparison a dodecylbenzesulfonic acid-based inhibitor provided inhibition at significantly higher concentrations (at least 40 times more).
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Ouled Ameur, Zied, Abdulla AlThawadi, and Borislav Grbic. "Selection, Implementation and Monitoring of Corrosion Inhibitors for Downhole Chemical Treatment on Rod/Beam Pump Wells Bahrain Fields." In International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-22329-ms.
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Abstract Corrosion is a naturally occurring phenomenon commonly defined as the destructive attack of a metal that results from a chemical or electrochemical reaction with its environment. The effect of corrosion in the oil and gas industry leads to economic loss, a loss of containment and associated impact on HSE and asset integrity. There are many technologies to bring the oil to the surface. Rod or Beam pumps are the most common form of artificial lift for oil wells in onshore oilfields. They are simple machines that have a long and well documented history in the industry and are economically inexpensive. Corrosion inhibitors are commonly used to mitigate electrochemical corrosion in the oilfield. When added in small quantities to an aggressive medium, these chemicals inhibit corrosion by changing the surface conditions of the metal surface. In downhole systems, the prevailing conditions may be very severe, resulting in high corrosion rates. Corrosion inhibitors can be applied downhole, however, the selection and application of a corrosion inhibitor for downhole is typically more challenging than for a surface application. The paper gives a brief view on the selection of the suitable corrosion inhibitor that meets the well condition. It will explain how to select the best application methods for downhole corrosion on Rod Wells. The paper also demonstrates how the downhole treatment for rod wells is carried out giving in depth details of the method that has been used. It will present the results of a downhole treatment case and make recommendations for a performance monitoring program to optimize a treatment program ensuring its success. Finally, the paper concludes with a case history of downhole corrosion inhibitor application from an onshore field in the Middle East with 550 producing wells, where downhole corrosion inhibitor was successfully applied to 165 wells, leading to a major reduction in tubing corrosion failures
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Radulescu, Victorita. "New Solution With Syntheses Inhibitors for the Chemical Cleaning of Organic Pollutants From the Water Supply System Of Generators." In ASME 2021 Power Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/power2021-64314.
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Abstract In thermal power plants, during the boilers functioning, heterogeneous deposits of substances must often be removed in order to prolong their operation and avoid their deterioration. The nature, type and quantity of deposits depend on the characteristics of the water supply systems and the chemical operating regime. For boilers with high deposits of copper and iron, the utilization of mineral acids for chemical cleaning is not quite effective, because their surfaces may be covered with a metal copper film. Organic impurities in the water supply affect the operation of steam generators, increasing electrical conductivity and lowering the pH. The heterogeneous composition of the deposits is unevenly distributed in the combustion system, making its cleaning a complex problem. For efficient chemical cleaning, the agents must have a minimal corrosive action on the metal surfaces, ensuring only the dissolution of the compounds on the surface of the boilers. To prevent corrosion of metals, inhibitors are introduced to diminish the reactions on the metal surface or at least to delay the kinetics of the reaction. This paper analyzes the implications of organic pollutants in the corrosion phenomena and chemical processes where they are involved. As an example, the power plant Borzesti affiliated to the Petrochemical Platform, Bacau County, Romania is presented. The adopted solution uses as an inhibitor, a synthesis between amino alcohol and a thiazole, in the presence of water. This inhibitor has been tested in the laboratory on different steels used in energy pipes, in different areas of the thermal circuits in the boiler, as pure steel or with different alloys. The methods used to reduce the effects of corrosion are briefly presented. Four classes of organic substances with properties of corrosion inhibitors in the organic acid environment were analyzed. The experimental results obtained, associated with a comparative analysis of corrosion rates, for different concentrations of inhibitors for a time interval of 4 hours are mentioned. In the second stage, the inhibitor behavior was analyzed for 6h and 8h. Corrosion rates are estimated by measuring the weight loss of the tested probes. Finally, the most suitable types of inhibitors, adapted at different metal compositions are presented, with a result in the cleaning of more than 98% of the surface of the boilers.
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Tan, Bee Chea, Ismail Mohd Saaid, Siti Qurratu’ Aini Mahat, Suzalina Zainal, Astriyana Anuar, and Petrus Tri Bhaskoro. "Adsorption and Squeeze Performance of PAMAM-PGLU Inhibitors for Silicate Scale Mitigation Due to ASP Flooding." In SPE International Conference on Oilfield Chemistry. SPE, 2023. http://dx.doi.org/10.2118/213866-ms.
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Abstract The dissolution of quartz mineral in sandstone reservoir due to chemical enhanced oil recovery (cEOR) processes, such as alkaline surfactant polymer (ASP) flooding has resulted in the scaling of silica and silicates around the wellbore formation and in the production wells. These scales can block and hinder the flow of producing fluids if left untreated. This will lead to reduced production rates as well as equipment damages eventually. The adsorption and squeeze performance of developed scale inhibitors that made up of polyamidoamine (PAMAM) dendrimers and pteroyl–L–glutamic acid (PGLU) was assessed in this paper. The results were compared to diethylenetriamine penta(methylene phosphonic acid), a commercial phosphonate scale inhibitor known as DETPMP. The crushed Berea sandstone core was soaked in scale inhibitor solutions for static adsorption test. Core flooding was performed to investigate the adsorption and retention of scale inhibitors in sandstone formation. The prediction of scale inhibitor squeeze performance was simulated based on core flooding data obtained. Laboratory results reveal PAMAM–2–PGLU scale inhibitor that comprises second generation PAMAM dendrimer exhibits the highest adsorption and retention in sandstone core. On top of that, the permeability of sandstone core was also increased with the treatment of PAMAM–PGLU scale inhibitors. SQUEEZE IV software also predicted that PAMAM–PGLU scale inhibitors yielded longer squeeze lifetime than DETPMP scale inhibitor. Both experimental and modelling results showed a good fit in terms of adsorption and squeeze lifetime. In this paper, the tested PAMAM–PGLU scale inhibitors demonstrate better adsorption, retention, and squeeze lifetime in sandstone formation. Although commercial scale inhibitors are effective at a wide range of reservoir conditions, the disposal of phosphonate scale inhibitors has raised concern due to their toxicity and low biodegradability. Hence, these developed PAMAM–PGLU scale inhibitors could be offered as environment–friendly and effective alternatives.
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Obeyesekere, Nihal U., Jonathan J. Wylde, Thusitha Wickramarachchi, and Lucious Kemp. "Formulation of High-Performance Corrosion Inhibitors in the 21St Century: Robotic High Throughput Experimentation and Design of Experiments." In SPE International Conference on Oilfield Chemistry. SPE, 2021. http://dx.doi.org/10.2118/204353-ms.
Full textAbstract:
Abstract Critical micelle concentration (CMC) is a known indicator for surfactants such as corrosion inhibitors’ ability to partition to water from two phase systems such as oil and water. Most corrosion inhibitors are surface active. At critical micelle concentration, the chemical is partitioned to water from the interface, physisorption on metallic surfaces and forms a physical barrier between steel and corrosive water. This protective barrier thus prevents corrosion initiating on the metal surface. When the applied chemical concentration is equal or higher than the CMC, the surfactant is partitioned to aqueous phase from the oil-water interface. This would lead to higher chemical availability of the inhibitor in water, preventing corrosion. Therefore, it was suggested that CMC can be used as an indicator to optimal chemical dose for corrosion control1-5. The lower the CMC of a corrosion inhibitor product, the better is this chemical for corrosion control as the availability of the chemical in the aqueous phase increases. This can achieve corrosion control with lesser amount of corrosion inhibitor product. Thus, increasing the performance of corrosion inhibitor product. In this work, the physical property, CMC, was used as an indicator to differentiate corrosion inhibitor performance. A vast array of corrosion inhibitor formulations was achieved by combinatorial chemical methods using Design of Experiment (DoE) methodologies and these arrays of chemical formulations were screened by utilizing high throughput screening (HTE)6-8, using CMC as the selection guide. To validate the concept, a known corrosion inhibitor formulation (Inhibitor Abz) was selected to optimize its efficacy. This formula contains several active ingredients and a solvent package. Three raw materials of this formulation were selected and varied in combinatorial fashion, keeping the solvents and other raw materials constant9. These three raw materials were blended in a random but in a controled manner utizing DoE and using combinatorial techniques. Instead of rapidly blending a large amount of formulations using robotics, the design of experiment (DoE) methods were utilized to constrain the number of blends. When attempting to discover the important factors, DoE gives a powerful suite of statistical methodologies10. In this work, Design Expert software utilizes DoE methods and this prediction model was used to explore a desired design space. The more relevant (not entirely random) formulations were generated by DoE methods, using Design Expert software that can effectively explore a desired design space. The Design of Experiment software mathematically analyzes the space in which fundamental properties are being measured. The development of an equally robust prescreening analysis was also developed. After blending a vast array of formulations by using automated workstation, these products were screened for CMC by utilizing an automated surface tension workstation. Several formulations with lower CMCs than the reference product (Inhibitor Abz) were discovered and identified for further study. The selected corrosion inhibitor formulations were blended in larger scales. The efficacy of these products was tested by classical laboratory testing methods such as rotating cylinder electrode (RCE) and rotating cage autoclave (RCA) to determine their performance as anti-corrosion agents. As the focus of this project was to optimize the corrosion Inhibitor Abz, this chemical was used as the reference product throughout of this work. The testing indicated that several new corrosion inhibitor formulations discovered from this work outperformed the original blend, thus validating the proof of concept.
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Wartenberg, Nicolas, Margaux Kerdraon, Mathieu Salaun, Lena Brunet-Errard, Christophe Fejean, and David Rousseau. "Evaluation and Optimization of Adsorption Reduction Strategies on Chemical EOR Economics." In International Petroleum Technology Conference. IPTC, 2021. http://dx.doi.org/10.2523/iptc-21810-ms.
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Abstract This paper is dedicated to the selection of the most effective way of mitigating surfactant adsorption in chemical EOR flooding. Mitigation strategies based on either water treatment or adsorption inhibitors were benchmarked for a sea water injection brine, on both performances and economics aspects. Performances in surfactant adsorption reduction were evaluated by applying salinity and/or hardness gradient strategies through dedicated water softening techniques, such as reverse osmosis or nanofiltration. Adsorption inhibitor addition, which does not require any water treatment, was also assessed and optimized for comparison. For each scenario, a suitable surfactant formulation was designed and evaluated through phase diagrams, static adsorption and diphasic coreflood experiments. Then the real benefit of surfactant adsorption reduction on the overall EOR process economics (including the costs of chemicals and water treatment) was assessed depending on the selected strategy. Sea water was considered as the injection brine for this study as it is widely used in chemical EOR process and often suffers high surfactant adsorption level. It was found that residual oil saturation after chemical flooding (SORc) dropped from 29% to 7% by applying a hardness gradient through nanofiltration process while 4% was reached with reverse osmosis. Regarding costs and footprint however, nanofiltration was found to be more advantageous. Adsorption inhibitors addition met similar performances to nanofiltration-based process (SORc=7%) and could be a valuable option depending on injected volume (pilot or small deployment) or field location (off-shore) as they do not require water treatment plant investment. Overall, this study provides useful practical insights on both performances and economics for selecting the most adapted strategy depending on the considered field case.
Reports on the topic "Chemical inhibitors"
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Chamovitz, Daniel A., and Zhenbiao Yang. Chemical Genetics of the COP9 Signalosome: Identification of Novel Regulators of Plant Development. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7699844.bard.
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This was an exploratory one-year study to identify chemical regulators of the COP9 signalosome. Chemical Genetics uses small molecules to modify or disrupt the function of specific genes/proteins. This is in contrast to classical genetics, in which mutations disrupt the function of genes. The underlying concept is that the functions of most proteins can be altered by the binding of a chemical, which can be found by screening large libraries for compounds that specifically affect a biological, molecular or biochemical process. In addition to screens for chemicals which inhibit specific biological processes, chemical genetics can also be employed to find inhibitors of specific protein-protein interactions. Small molecules altering protein-protein interactions are valuable tools in probing protein-protein interactions. In this project, we aimed to identify chemicals that disrupt the COP9 signalosome. The CSN is an evolutionarily conserved eight-subunit protein complex whose most studied role is regulation of E3 ubiquitinligase activity. Mutants in subunits of the CSN undergo photomorphogenesis in darkness and accumulate high levels of pigments in both dark- and light-grown seedlings, and are defective in a wide range of important developmental and environmental-response pathways. Our working hypothesis was that specific molecules will interact with the CSN7 protein such that binding to its various interacting proteins will be inhibited. Such a molecule would inhibit either CSN assembly, or binding of CSN-interacting proteins, and thus specifically inhibit CSN function. We used an advanced chemical genetic screen for small-molecule-inhibitors of CSN7 protein-protein interactions. In our pilot study, following the screening of ~1200 unique compounds, we isolated four chemicals which reproducibly interfere with CSN7 binding to either CSN8 or CSN6.
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Mirica, Liviu M., and Barbara Casella. Specific Inhibitors of Histone Demethylases: Novel Chemical Agents for Breast Cancer Therapy. Fort Belvoir, VA: Defense Technical Information Center, August 2012. http://dx.doi.org/10.21236/ada576183.
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Perrimon, Norbert. Parallel Genomic and Chemical Screens to Identify Both Therapeutic Targets and Inhibitors of These Targets in the Treatment of Neurofibromatosis. Fort Belvoir, VA: Defense Technical Information Center, December 2006. http://dx.doi.org/10.21236/ada465264.
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Weiss. PR-318-06701-R01 Predicting and Mitigating Salt Precipitation. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), February 2009. http://dx.doi.org/10.55274/r0010976.
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Brine solutions are often produced during gas storage operations, and when these solutions encounter changing temperature or pressure, salt can precipitate. This salt (NaCl) can impair productivity and may even result in abandonment of wells. Dilution with fresh water is the preferred method of mitigating the salt buildup. Existing salt deposits are dissolved with fresh water. Additionally, fresh water is used as a produced water diluent to reduce supersaturation with respect to NaCl. However, this can be expensive depending on the method of application, and as fresh water becomes scarcer, the method will become more expensive. A number of chemicals are reported to reduce or prevent salt deposition. Among them are ferrocyanide and some organic molecules such as nitrilotriacetic acid and nitrilotriacetamide (NTAm). These inhibitors are thought to prevent salt precipitation by crystal modification or by interfering with crystal growth. Their effectiveness, however, varies with their concentration and the chemistry of the brines. For example, ferrocyanide is a very effective salt inhibitor; however, at low pH or in the presence of large amounts of iron it decomposes rendering it ineffective. As shown in Figs. 1 and 2 where supersaturated solutions of NaCl are cooled to room temperature, the performance of both chemicals is reduced as the reservoir water increases in calcium and/or magnesium, eventually becoming ineffective. But even when precipitate is formed, both inhibitors affect the properties of the precipitate so that there is no caking with no tendency to form large crystals associated with sodium chloride scale. The questions concerning the environmental issues associated with ferrocyanide that arose during Phase I are addressed in this report.
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Pound, B. G. GRI-99-0000 Gap Analysis of the GRI Research Program on Internal Corrosion. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), December 1999. http://dx.doi.org/10.55274/r0010720.
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Extensive information on the corrosion of steel in aqueous CO2 systems is now available from this program and numerous other sources. This information was reviewed to identify what research has been performed and what research remains to be undertaken to develop a expert system/risk management program. Four areas were examined: corrosion mechanisms, mitigation strategies, monitoring techniques, and models/risk assessment. There were five gaps in mechanisms (two for bacteria and one each for flow rate/chloride concentration, hydrocarbons, and organic acids) and four gaps in mitigation (antibiofilm additives, antibacterial corrosion inhibitors, antibiofilm coatings, and UV light). Monitoring techniques have one principal gap, which is the lack of a single sensor that can indicate the type of corrosion and whether bacteria are involved. Various gaps were found in the approaches used for modeling and risk assessment: semiempirical and mechanistic models (deficient in their ability to treat films, H2S, and bacteria); thermodynamic models (incomplete range of key chemical species); statistical models (limited testing); probabilistic risk assessment (lack of usable data); and ranking risk assessment (lack of appropriate algorithms for internal corrosion).
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Vera, Jose, and Ken Evans. PR186-203600-Z01 Impact of Drag Reducing Agents on Corrosion Management. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), October 2021. http://dx.doi.org/10.55274/r0012177.
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The purpose of this research was to understand the potential impact of drag reducing agents (DRA) on internal corrosion of liquid hydrocarbon pipelines. The first task of this project included a comprehensive review of literature and knowledge, both in public domain and from industry experience, on the effect of DRA on water and solid transport in liquid hydrocarbons, and possible interactions with other performance chemicals typically used in the oil and gas industry. This was the basis for defining the final bench test methodology and test matrix to be performed in the second task. A novel bench-top apparatus was designed based on a vertical Couette cell approach, and a test methodology was successfully implemented to evaluate the potential effect(s) of DRA on water accumulation and localized corrosion at the oil/water interface. A test matrix was conducted with two DRAs (a water based and an oil based) and two corrosion inhibitors (a water soluble and an oil soluble) at a given test condition (3.5% NaCl saturated with 97%CO2/3%O2, pH ~6 at 80 oF). There is a related webinar.
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Shoseyov, Oded, Steven A. Weinbaum, Raphael Goren, and Abhaya M. Dandekar. Biological Thinning of Fruit Set by RNAase in Deciduous Fruit Trees. United States Department of Agriculture, August 1993. http://dx.doi.org/10.32747/1993.7568110.bard.
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Fruit thinning is a common and necessary practice for commercial fruit production in many deciduous tree fruit species. Fruit thinning in apple may be accomplished with a variety of chemical thinning agents, but the use of these chemicals is a subject of environmental concern. It has been shown recently that RNase enzyme, secreted from the stigma and the style, inhibits pollen germination and pollen tube elongation. In this study we have been able to show that Aspergillus niger B-1 RNase can effectively inhibit peach and apple pollen germination, and tube elongation in-vitro, as well as thin fruit in peach and apple, and reduce the number of seeds in citrus. The objectives of the research were to detrmine the conditions for effective thinning of (USA and Israel), develop fermentation process for cost effective production of RNase from A. niger. (Israel), and clone apple S-RNase cDNA (USA). All the objectives of the research were addressed. We have determined the optimal fermentation conditions for cost effective production of the A. niger at a 20,000 liters scale. TheA. niger B1 RNase was isolated to homogeneity and its kinetic and biochemical properties including its N-terminal sequence were fully characterized. The field test results both in Israel and California have shown variability in effectiveness and more work is needed to define the RNase concentration necessary to completely inhibit pollen development. Plant transformation vectors expressing anti-sense apple S-RNase genes were constructed (USA) with an attempt to produce self compatible transgenic apple trees. Bovine S-Protein cDNA was cloned and successfully expressed in E. coli (Israel). Plant transformation vector expressing the S-Protein gene was constructed (USA) with an attempt to produce transgenic plants expressing S-protein in the style. Exogenous application of S-peptide to these plants will result in active RNase and consequently prevention of fertilization.
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Pesis, Edna, Elizabeth J. Mitcham, Susan E. Ebeler, and Amnon Lers. Application of Pre-storage Short Anaerobiosis to Alleviate Superficial Scald and Bitter Pit in Granny Smith Apples. United States Department of Agriculture, January 2013. http://dx.doi.org/10.32747/2013.7593394.bard.
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There is increased demand for high quality fruit produced and marketed with reduced chemical inputs to minimize toxic effects on human health and the environment. Granny Smith (GS) apple quality is reduced by two major physiological disorders, superficial scald and bitter pit (BP). These disorders cause great loss to apple growers worldwide. Superficial scald is commonly controlled by chemical treatments, mainly the antioxidant diphenylamine (DPA) and/or the ethylene action inhibitor, 1-methylcyclopropene (1–MCP). Both chemicals are ineffective in controlling bitter pit incidence. We proposed to investigate the beneficial use of non-chemical, abiotic stress with low O2 (LO2) applied for 10d at 20°C on GS apple fruit. During the project we expanded the treatment to more apple cultivars, Golden Delicious (GD) and Starking Delicious (SD) and another pome fruit, the pear. Apple and pear have similar physiological disorders that develop during cold storage and we examined if the LO2 treatment would also be effective on pear. Application of 0.5% LO2 atmosphere for 10d at 20°C or 500ppb 1-MCP at 20°C prior to cold storage at 0°C, was effective in reducing superficial scald in GS apple. Moreover, LO2 pretreatment was also effective in reducing bitter pit (BP) development in California GS and Israeli GD and SD apples The BP symptoms in GS from California were much more prominent, so the effect of LO2 was more dramatic than the effect on the Israeli cvs. GD and SD, nevertheless the LO2 treatment showed the same trend in all cultivars in reducing BP. The LO2 and 1-MCP -treated fruit exhibited lower levels of ethylene, - farnesene and its oxidation product, 6-methyl-5-hepten-2-one (MHO), as determined by SPME/GC-MS analysis. In addition, LO2 pretreatment applied to California Bartlett or Israeli Spadona pears was effective in reducing superficial scald, senescent scald and internal breakdown after 4 m of cold storage at 0°C. For GS apple, low-temperature storage resulted in oxidative stress and chilling injury, caused by increased production of superoxide anions which in turn led to the generation of other dangerous reactive oxygen species (ROS). Using confocal laser-scanning microscopy and H2O2 measurements of apple peel, we observed ROS accumulation in control fruit, while negligible amounts were found in LO2 and 1-MCP treated fruit. Gene-expression levels of ROS-scavenging enzymes were induced by the various pretreatments: catalase was induced by LO2 treatment, whereas Mn superoxide dismutase was induced by 1-MCP treatment. We assume that LO2 and 1-MCP pretreated fruit remained healthier due to reduced production of ethylene and reactive oxygen substances, such as MHO, during cold storage. The LO2-treated apple exhibited greener peel and firmer fruit after 6 m of cold storage, and the fruit had high crispiness leading to high taste preference. In both pear cultivars, the LO2 treatment led to a reduction in internal breakdown and browning around the seed cavity. We tested the LO2 pre-storage treatment on a semi-commercial scale that would be applicable to a small organic grower by sealing the fruit within the plastic field bins. The treatment was most effective with a continuous flow of nitrogen through the bins; however, a single 6 hour flush of nitrogen was also fairly effective. In addition, we determined that it was very important to have the oxygen levels below 0.5% for approximately 10 days to achieve good scald control, not counting the time required to reduce the oxygen concentration. Our LO2 technology has been proven in this project to be effective in reducing several physiological disorders developed in pome fruit during cold storage. We hope that our non-chemical treatment which is friendly to the environment will be used in the near future for the organic apple and pear industry. The next step should be an analysis of the cost-benefits and commercial feasibility.
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Jasbir Gill. A Synergistic Combination of Advanced Separation and Chemical Scale Inhibitor Technologies for Efficient Use of Imparied Water As Cooling Water in Coal-based Power Plants. Office of Scientific and Technical Information (OSTI), August 2010. http://dx.doi.org/10.2172/1011486.
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Rafaeli, Ada, Wendell Roelofs, and Anat Zada Byers. Identification and gene regulation of the desaturase enzymes involved in sex-pheromone biosynthesis of pest moths infesting grain. United States Department of Agriculture, March 2008. http://dx.doi.org/10.32747/2008.7613880.bard.
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The original objectives of the approved proposal included: 1. Establishment of the biosynthetic pathways for pheromone production using labeled precursors and GC-MS. 2. The elucidation of a circadian regulation of key enzymes in the biosynthetic pathway. 3. The identification, characterization and confirmation of functional expression of the delta-desaturases. 4. The identification of gene regulatory processes involved in the expression of the key enzymes in the biosynthetic pathway. Background to the topic: Moths constitute one of the major groups of pest insects in agriculture and their reproductive behavior is dependent on chemical communication. Sex-pheromone blends are utilized by a variety of moth species to attract conspecific mates. The sex pheromones used are commonly composed of blends of aliphatic molecules that vary in chain length, geometry, degree and position of double bonds and functional groups. They are formed by various actions of specific delta-desaturases to which chain shortening, elongation, reduction, acetylation, and oxidation of a common fatty acyl precursor is coupled. In most of the moth species sex-pheromone biosynthesis is under circadian control by the neurohormone, PBAN (pheromone-biosynthesis-activating neuropeptide). The development of specific and safe insect control strategies utilizing pheromone systems depends on a clear knowledge of the molecular mechanisms involved. In this proposal we aimed at identifying and characterizing specific desaturases involved in the biosynthetic pathway of two moth pest-speciesof stored products, P. interpunctella and S. cerealella, and to elucidate the regulation of the enzymes involved in pheromone biosynthesis. Due to technical difficulties the second stored product pest was excluded from the study at an early phase of the research project. Major conclusions: Within the framework of the planned objectives we confirmed the pheromone biosynthetic pathway of P. interpunctella and H. armigera by using labeled precursor molecules. In addition, in conjunction with various inhibitors we determined the PBAN-stimulated rate-limiting step for these biosynthetic pathways. We thereby present conclusive evidence that the enzyme Acetyl Coenzyme A Carboxylase is activated as a result of PBAN stimulation. We also found that P. interpunctella produce the main pheromone component Z9, E12 Tetradecenyl acetate through the action of a D11 desaturase working on the 16:Acid precursor. This is evidenced by the high amount of incorporation of ²H-labeled 16:Acid into pheromone when compared to the incorporation of ²H-labeled 14:Acid. However, in contrast to reports on other moth species, P. interpunctella is also capable of utilizing the 14:Acid precursor, although to a much lesser extent than the 16:Acid precursor. Despite the discovery of nine different desaturase gene transcripts in this species, from the present study it is evident that although PCR detected all nine gene transcripts, specific to female pheromone glands, only two are highly expressed whereas the other 7 are expressed at levels of at least 10⁵ fold lower showing very low abundance. These two genes correspond to D11-like desaturases strengthening the hypothesis that the main biosynthetic pathway involves a D11 desaturase.