Science.gov

Sample records for biguanide derivatives chemical

  1. Copper-catalyzed arylation of biguanide derivatives via C-N cross-coupling reactions.

    PubMed

    Zhang, Chen; Huang, Bo; Bao, Ai-Qing; Li, Xiao; Guo, Shunna; Zhang, Jin-Quan; Xu, Jun-Zhi; Zhang, Rihao; Cui, Dong-Mei

    2015-12-21

    An efficient copper-catalyzed cross-coupling reaction of biguanide hydrochloride derivatives with both aryl iodides and bromides under mild conditions has been developed. The reaction occurred in good yields and tolerated aryl halides containing functionalities such as nitriles, sulfonamides, ethers, and halogens. Alkyl and cyclic substituted biguanidines were also well tolerated. PMID:26444146

  2. Optimization of biguanide derivatives as selective antitumor agents blocking adaptive stress responses in the tumor microenvironment

    PubMed Central

    Narise, Kosuke; Okuda, Kensuke; Enomoto, Yukihiro; Hirayama, Tasuku; Nagasawa, Hideko

    2014-01-01

    Adaptive cellular responses resulting from multiple microenvironmental stresses, such as hypoxia and nutrient deprivation, are potential novel drug targets for cancer treatment. Accordingly, we focused on developing anticancer agents targeting the tumor microenvironment (TME). In this study, to search for selective antitumor agents blocking adaptive responses in the TME, thirteen new compounds, designed and synthesized on the basis of the arylmethylbiguanide scaffold of phenformin, were used in structure activity relationship studies of inhibition of hypoxia inducible factor (HIF)-1 and unfolded protein response (UPR) activation and of selective cytotoxicity under glucose-deprived stress conditions, using HT29 cells. We conducted luciferase reporter assays using stable cell lines expressing either an HIF-1-responsive reporter gene or a glucose-regulated protein 78 promoter-reporter gene, which were induced by hypoxia and glucose deprivation stress, respectively, to screen for TME-targeting antitumor drugs. The guanidine analog (compound 2), obtained by bioisosteric replacement of the biguanide group, had activities comparable with those of phenformin (compound 1). Introduction of various substituents on the phenyl ring significantly affected the activities. In particular, the o-methylphenyl analog compound 7 and the o-chlorophenyl analog compound 12 showed considerably more potent inhibitory effects on HIF-1 and UPR activation than did phenformin, and excellent selective cytotoxicity under glucose deprivation. These compounds, therefore, represent an improvement over phenformin. They also suppressed HIF-1- and UPR-related protein expression and secretion of vascular endothelial growth factor-A. Moreover, these compounds exhibited significant antiangiogenic effects in the chick chorioallantoic membrane assay. Our structural development studies of biguanide derivatives provided promising candidates for a novel anticancer agent targeting the TME for selective cancer therapy, to be subjected to further in vivo study. PMID:24944508

  3. Environmental fate of polyhexamethylene biguanide.

    PubMed

    Lucas, Anne D

    2012-03-01

    Polyhexamethylene biguanide (PHMB) is used as a bacteriocidal agent in a variety of applications from medical devices to pools, but is highly toxic to some aquatic species. The stability of PHMB in various environmental matrices was examined. 80% of PHMB was present in fortified creek samples after 20 days, but bound immediately to soils with the exception of sandy soil. PHMB was absorbed to below detectable levels by weathered concrete within 12 h. In addition, one over the counter wound care product containing PHMB was evaluated to assess environmental leaching; detectable levels (20 ?g/mL) were still present after 1 week. PMID:22037631

  4. Phagocytosis Affects Biguanide Sensitivity of Acanthamoeba spp.

    PubMed Central

    Noble, Judith A.; Ahearn, Donald G.; Avery, Simon V.; Crow Jr., Sidney A.

    2002-01-01

    The incidence of Acanthamoeba keratitis, a disease associated with contact lens wear, has been in apparent decline with the advent of multipurpose contact lens solutions. The concentrations of the biguanides chlorhexidine digluconate (CHX) and particularly polyhexamethylene biguanide (PHMB) included in multipurpose solutions (MPSs) are sublethal for amoebae. We evaluated by flow cytometry the effects of these two biguanides on phagocytosis of particles and the survival of trophozoites of Acanthamoeba castellanii and A. polyphaga. Trophozoites of A. castellanii and A. polyphaga (106/ml) were exposed to solutions of 5 and 50 μg of PHMB and CHX per ml in the presence and absence of particles (i.e., heat-killed yeasts and bacteria and latex beads). In addition, trophozoites were exposed to particles treated with these concentrations of the two biguanides. In the absence of particles, trophozoites of A. polyphaga appeared to be more resistant to the biguanides than those of A. castellanii. In the presence of particles, the rates of survival of both species were decreased. In most instances, particles treated with sublethal concentrations of both biguanides that were adsorbed onto the particles reduced the incidence of phagocytosis. Particles present in MPSs in contact lens cases may be involved in the decreased incidence of Acanthamoeba keratitis. PMID:12069957

  5. Biguanide related compounds in traditional antidiabetic functional foods.

    PubMed

    Perla, Venu; Jayanty, Sastry S

    2013-06-01

    Biguanides such as metformin are widely used worldwide for the treatment of type-2 diabetes. The identification of guanidine and related compounds in French lilac plant (Galega officinalis L.) led to the development of biguanides. Despite of their plant origin, biguanides have not been reported in plants. The objective of this study was to quantify biguanide related compounds (BRCs) in experimentally or clinically substantiated antidiabetic functional plant foods and potatoes. The corrected results of the Voges-Proskauer (V-P) assay suggest that the highest amounts of BRCs are present in green curry leaves (Murraya koenigii (L.) Sprengel) followed by fenugreek seeds (Trigonella foenum-graecum L.), green bitter gourd (Momordica charantia Descourt.), and potato (Solanum tuberosum L.). Whereas, garlic (Allium sativum L.), and sweet potato (Ipomea batatas (L.) Lam.) contain negligible amounts of BRCs. In addition, the possible biosynthetic routes of biguanide in these plant foods are discussed. PMID:23411283

  6. Analysis of polyhexamethylene biguanide in multipurpose contact lens solutions.

    PubMed

    Lucas, Anne D; Gordon, Edward A; Stratmeyer, Melvin E

    2009-12-15

    The objective of this study was to establish a reasonably simple and reliable method to measure very low concentrations of polyhexamethylene biguanide (PHMB) in multipurpose contact lens solutions (MPSs). By using a weak cation exchange solid phase extraction cartridge to extract the PHMB from MPS, followed by HPLC analysis using an evaporative light scattering detector, low levels (0.1 ppm) of PHMB were detected. Application of this method to a series of off-the-shelf MPS with PHMB as the active ingredient demonstrated these solutions contain 1 ppm. The contact lens solution with hydrogen peroxide as the active ingredient gave no peak where the PHMB peak eluted. The Polyquad contact lens solution generated a peak close to the retention time of PHMB. Recovery of PHMB from fortified hydrogen peroxide contact lens solution was good at 0.25 ppm and above; 105% with a RSD of 17% or less. The repeatability of the HPLC system ranged from 4 to 11% RSD; the reproducibility of the entire method was less than 17.5% RSD. Storage and stability studies indicated that storage of MPS with PHMB for chemical analysis are not temperature dependent, but are affected by the composition of the container in which the contact lens solution is stored. PMID:19836589

  7. Metformin and Other Biguanides in Oncology: Advancing the Research Agenda

    PubMed Central

    Pollak, Michael

    2010-01-01

    Retrospective studies suggest that diabetics treated with metformin have a substantially reduced cancer burden compared with other diabetics, studies that may be impractical to confirm prospectively. It is unclear if this reflects a chemopreventive effect, an effect on transformed cells, or both. It also remains to be established if these data have relevance to people without diabetes. Laboratory models, however, provide independent impressive evidence for activity of metformin and other biguanides in both cancer treatment and chemoprevention. Investigations of biguanide mechanisms have revealed considerable complexity and have identified important gaps in knowledge that should be addressed to ensure the optimal design of clinical trials of these agents. Such trials may define important new indications of biguanides for the prevention and/or treatment of many common cancers. PMID:20810670

  8. Selective inhibition of deactivated mitochondrial complex I by biguanides.

    PubMed

    Matsuzaki, Satoshi; Humphries, Kenneth M

    2015-03-24

    Biguanides are widely used antihyperglycemic agents for diabetes mellitus and prediabetes treatment. Complex I is the rate-limiting step of the mitochondrial electron transport chain (ETC), a major source of mitochondrial free radical production, and a known target of biguanides. Complex I has two reversible conformational states, active and de-active. The deactivated state is promoted in the absence of substrates but is rapidly and fully reversed to the active state in the presence of NADH. The objective of this study was to determine the relative sensitivity of active/de-active complex I to biguanide-mediated inhibition and resulting superoxide radical (O?(?)) production. Using isolated rat heart mitochondria, we show that deactivation of complex I sensitizes it to metformin and phenformin (4- and 3-fold, respectively), but not to other known complex I inhibitors, such as rotenone. Mitochondrial O?(?) production by deactivated complex I was measured fluorescently by NADH-dependent 2-hydroxyethidium formation at alkaline pH to impede reactivation. Superoxide production was 260.4% higher than in active complex I at pH 9.4. However, phenformin treatment of de-active complex I decreased O?(?) production by 14.9%, while rotenone increased production by 42.9%. Mitochondria isolated from rat hearts subjected to cardiac ischemia, a condition known to induce complex I deactivation, were sensitized to phenformin-mediated complex I inhibition. This supports the idea that the effects of biguanides are likely to be influenced by the complex I state in vivo. These results demonstrate that the complex I active and de-active states are a determinant in biguanide-mediated inhibition. PMID:25719498

  9. Chemical Sensors Based on Cyclodextrin Derivatives

    PubMed Central

    Ogoshi, Tomoki; Harada, Akira

    2008-01-01

    This review focuses on chemical sensors based on cyclodextrin (CD) derivatives. This has been a field of classical interest, and is now of current interest for numerous scientists. First, typical chemical sensors using chromophore appended CDs are mentioned. Various “turn-off” and “turn-on” fluorescent chemical sensors, in which fluorescence intensity was decreased or increased by complexation with guest molecules, respectively, were synthesized. Dye modified CDs and photoactive metal ion-ligand complex appended CDs, metallocyclodextrins, were also applied for chemical sensors. Furthermore, recent novel approaches to chemical sensing systems using supramolecular structures such as CD dimers, trimers and cooperative binding systems of CDs with the other macrocycle [2]rotaxane and supramolecular polymers consisting of CD units are mentioned. New chemical sensors using hybrids of CDs with π-conjugated polymers, peptides, DNA, nanocarbons and nanoparticles are also described in this review.

  10. The response of Escherichia coli to exposure to the biocide polyhexamethylene biguanide.

    PubMed

    Allen, Michael J; White, Graham F; Morby, Andrew P

    2006-04-01

    The global response of Escherichia coli to the broad-spectrum biocide polyhexamethylene biguanide (PHMB) was investigated using transcriptional profiling. The transcriptional analyses were validated by direct determination of the PHMB-tolerance phenotypes of derivatives of E. coli MG1655 carrying either insertionally inactivated genes and/or plasmids expressing the cognate open reading frames from a heterologous promoter in the corresponding chromosomally inactivated strains. The results showed that a wide range of genes was altered in transcriptional activity and that all of the corresponding knockout strains subsequently challenged with biocide were altered in tolerance. Of particular interest was the induction of the rhs genes and the implication of enzymes involved in the repair/binding of nucleic acids in the generation of tolerance, suggesting a novel dimension in the mechanism of action of PHMB based on its interaction with nucleic acids. PMID:16549663

  11. Occupationally derived chemicals in breast milk

    SciTech Connect

    Wolff, M.S.

    1983-01-01

    Exogenously derived chemicals have been widely reported in breast milk. Chemicals typically found in occupational exposures, including trace metals, solvents, and halogenated hydrocarbons, are reviewed, in terms of milk partition factors, potential infant exposures, and possible infant health effects. In addition to ingestion of a chemical from breast milk, an infant incurs a neonatal body burden of a chemical due to transplacental migration from maternal blood. For trace metals, neonatal blood levels are similar to maternal blood levels. Partition of metals to milk is less efficient, but nevertheless can contribute significantly to an infant's body burden. For lipid-soluble pesticide residues and halogenated biphenyls, neonatal body burden is much less than that of the mother, but transfer to milk is efficient, due to the high proportion of milk fat. It is suggested that potential organic mercury toxicity can be estimated from concentration in maternal blood or milk. For other chemicals, available data are not sufficient to evaluate short- or long-term health effects. However, for many halogenated hydrocarbons, concentrations in normal human milk would permit infant exposure above guidelines for allowable daily intake set by the World Health organization.

  12. Polyhexamethylene biguanide functionalized cationic silver nanoparticles for enhanced antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Ashraf, Sumaira; Akhtar, Nasrin; Ghauri, Muhammad Afzal; Rajoka, Muhammad Ibrahim; Khalid, Zafar M.; Hussain, Irshad

    2012-05-01

    Polyhexamethylene biguanide (PHMB), a broad spectrum disinfectant against many pathogens, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles. The particles formed were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering, electrophoretic mobility, and TEM to measure their morphology and surface chemistry. PHMB-functionalized silver nanoparticles were then evaluated for their antimicrobial activity against a gram-negative bacterial strain, Escherichia coli. These silver nanoparticles were found to have about 100 times higher bacteriostatic and bactericidal activities, compared to the previous reports, due to the combined antibacterial effect of silver nanoparticles and PHMB. In addition to other applications, PHMB-functionalized silver nanoparticles would be extremely useful in textile industry due to the strong interaction of PHMB with cellulose fabrics.

  13. In Vitro and In Vivo Modulation of Alternative Splicing by the Biguanide Metformin.

    PubMed

    Laustriat, Delphine; Gide, Jacqueline; Barrault, Laetitia; Chautard, Emilie; Benoit, Clara; Auboeuf, Didier; Boland, Anne; Battail, Christophe; Artiguenave, François; Deleuze, Jean-François; Bénit, Paule; Rustin, Pierre; Franc, Sylvia; Charpentier, Guillaume; Furling, Denis; Bassez, Guillaume; Nissan, Xavier; Martinat, Cécile; Peschanski, Marc; Baghdoyan, Sandrine

    2015-01-01

    Major physiological changes are governed by alternative splicing of RNA, and its misregulation may lead to specific diseases. With the use of a genome-wide approach, we show here that this splicing step can be modified by medication and demonstrate the effects of the biguanide metformin, on alternative splicing. The mechanism of action involves AMPK activation and downregulation of the RBM3 RNA-binding protein. The effects of metformin treatment were tested on myotonic dystrophy type I (DM1), a multisystemic disease considered to be a spliceopathy. We show that this drug promotes a corrective effect on several splicing defects associated with DM1 in derivatives of human embryonic stem cells carrying the causal mutation of DM1 as well as in primary myoblasts derived from patients. The biological effects of metformin were shown to be compatible with typical therapeutic dosages in a clinical investigation involving diabetic patients. The drug appears to act as a modifier of alternative splicing of a subset of genes and may therefore have novel therapeutic potential for many more diseases besides those directly linked to defective alternative splicing. PMID:26528939

  14. [Preventing nosocomial infections. Dressings soaked in polyhexamethylene biguanide (PHMB)].

    PubMed

    Salas Campos, Luis; Gmez Ferrero, Ona; Estudillo Prez, Vanesa; Fernndez Mansilla, Marta

    2006-06-01

    Polyhexamethlene biguanide (PHMB) is an antibacterial agent included in the chlorhexidine group which is active against a wide number of microorganisms including Staphylococcus Aureus Methycilin Resistant (MRSA), Vancomycin Resistant Enterococcus Faecalis (VRE) and Acinetobacter baumannii which all cause antibiotic-resistant infections. Traditionally gauze dressings have been used to cover and protect wounds although their porous structure does not constitute an efficient barrier against bacterial penetration, especially when a dressing becomes wet due to the effects of a wound oozing and draining. Recently the use of a dressing soaked in a 0.2% PHMB solution which works as a biological barrier against pathogenic agents has been introduced in clinical practice. On the one hand, this PHMB soaked dressing inhibits bacterial growth in the areas where it is applied and, on the other hand, it prevents the penetration of microorganisms through the dressing itself. Simultaneously while a PHMB soaked dressing carries out these actions, it creates an environment favorable to the proliferation of the normal flora found in the epidermis. As opposed to porous gauze dressings, a PHMB dressing remains active during 72 hours even in wet environs. Its wide anti-micro-bacterial range prevents infections in surgical, acute or chronic wounds and in any type of intra-corporal access susceptible to infection, such as by means of intravascular catheters, tracheotomies, or thoracic tubes. A PHMB dressing can also be used as a primary covering to treat a chronic wound since it does not interfere in the process of tissue reepithelization. PMID:16875365

  15. Study of epigenetic properties of Poly(HexaMethylene Biguanide) hydrochloride (PHMB).

    PubMed

    Creppy, Edmond E; Diallo, Aboudoulatif; Moukha, Serge; Eklu-Gadegbeku, Christophe; Cros, Daniel

    2014-08-01

    Poly(HexaMethylene Biguanide) hydrochloride (PHMB) CAS No. [32289-58-0] is a particularly effective member of the biguanides antiseptic chemical group, and has been in use since the early fifties in numerous applications. It has been proposed that PHMB be classified as a category 3 carcinogen although PHMB is not genotoxic. It has been hypothesized that PHMB may have epigenetic properties effects, including non-genotoxic modifications of DNA bases, DNA methylation and mitogenic cytokine production. These properties have been assessed in vitro using 3 cell types: Caco-2 cells (from a human colon adenocarcinoma) with a non-functional p53 gene. (?p53: mut p53), N2-A (Neuro-2A cells, mouse neural cells), the brain being a possible target organ in rodents and HepG2 cells (human hepatocellular carcinoma) with functional p53 gene. From the concentration 1 g/mL up to 20 g/mL of PHMB, no effect was observed, either growth stimulation or inhibition. Viability testing using neutral red led to an IC 50 of 20-25 g/mL after treatment with PHMB for 3 h, whereas the MTT test led to IC50 values of 80 g/mL, 160 g/mL and 160 g/mL respectively for HepG2 cells, Neuro-2A cells and Caco-2 cells. PHMB does not induce significant oxidative stress (production of MDA or lipoperoxidation, nor does it induce hydroxylation of DNA (8-OH-dG) and/or its hypermethylation (m5dC), the latter being strongly implicated in DNA replication and regulation and cell division. PHMB does not induce significant production of mitogenic cytokines such as TNF-? (tumor necrosis factor), interleukins (IL-1 alpha), and the transcription factor nuclear factor kappa B (NF-?B) which can cause either apoptosis or stimulate the growth of transformed cells or tumors. Instead, from concentrations of 20 to 100 g/mL, PHMB kills cells of all types in less than 3 h. The expression of genes involved in the mechanisms of cell death induced by PHMB, including p53, the pro apoptotic gene bax and others, the anti-apoptotic bcl-2 and caspase-3 has been evaluated by RT-PCR. Finally, the status of GAP-junctions (GJIC) in the presence of PHMB has been determined and appeared to not be significantly affected. Taken together the data show that in vitro PHMB does not exhibit clear and remarkable epigenetic properties except a slight increase of some cytokines and transcription factor at higher concentrations at which cell lysis occurs rapidly. PMID:25111876

  16. Production of Chemical Derivatives from Renewables

    SciTech Connect

    Davison, Brian; Nghiem, John; Donnelly, Mark; Tsai, Shih-Perng; Frye, John; Landucci, Ron; Griffin, Michael

    1996-06-01

    The purpose of this Cooperative Research and Development Agreement (CRADA) between Lockheed Martin Energy Research Corp., (LMER), Argonne National Laboratory (ANL), National Renewable Energy Laboratory (NREL), and Battelle Memorial Institute, operator of Pacific Northwest National Laboratory (PNNL), (collectively referred to as the 'Contractor'), and Applied Carbochemicals, Inc. (Participant) was to scale-up from bench results an economically promising and competitive process for the production of chemical derivatives from biologically produced succinic acid. The products that were under consideration for production from the succinic acid platform included 1,4-butanediol, {gamma}y-butyrolactone, 2-pyrrolidinone and N-methyl pyrrolidinone. Preliminary economic analyses indicated that this platform was competitive with the most recent petrochemical routes. The Contractors and participant are hereinafter jointly referred to as the 'Parties.' Research to date in succinic acid fermentation, separation and genetic engineering resulted in a potentially economical process based on the use of an Escherichia coli strain AFP111 with suitable characteristics for the production of succinic acid from glucose. Economic analysis has shown that higher value commodity chemicals can be economically produced from succinic acid based on preliminary laboratory findings and predicted catalytic parameters. At the time, the current need was to provide the necessary laboratory follow-up information to properly optimize, design and operate a pilot scale process. The purpose of the pilot work was to validate the integrated process, assure 'robustness' of the process, define operating conditions, and provide samples for potential customer evaluation. The data from the pilot scale process was used in design and development of a full scale production facility. A new strain, AFP111 (patented), discovered at ANL was tested and developed for process use at the Oak Ridge National Laboratory (ORNL) and ANL. The operability and product formation are attractive for this strain and effort was being directed at process development and optimization. Key to the transition from the fermentative production unit operation to the chemical catalysis is the 'clean-up' of fermentation broth, succinic acid formation from the salt, and succinic acid concentration. These steps are accomplished by a two-stage membrane ED separation process developed at AWL. Although the current process is well developed, possible modifications and optimization may be called for as development work continues in both the fermentation and catalysis areas. Research to date performed at PNNL has demonstrated that succinic acid can be converted to value added chemicals such as 1,4-butanediol, {gamma}-butyrolactone, N-methyl pyrrolidinone, and 2 pyrrolidinone with high conversion and selectivities. Continued research will be performed in catalyst development and reaction condition optimization to move this work from the bench scale to the pilot scale. All development of the process was guided by the NREL technoeconomic model. The model showed that direct aqueous phase catalysis of succinic acid to 1,4-butanediol, {gamma}-butyrolactone, and N-methyl pyrrolidinone provided significant economical advantages in the market, the margin, and the return on capital investment over existing petrochemical processes for production of these compounds. The model also provided the baseline for evaluating current laboratory research. As data from the bench and pilot work were made available the model was modified and appropriate sensitivities ran to determine impact of the process changes and optimization. The report will present the planned CRADA tasks followed by the results. The results section has an overall project summary follwed by more detailed reports from the participants. This is a nonproprietary report; additional proprietary information may be made available subject to acceptance of the appropriate proprietary information agreements.

  17. Fucoxanthin Derivatives: Synthesis and their Chemical Properties.

    PubMed

    Komba, Shiro; Kotake-Nara, Eiichi; Machida, Sachiko

    2015-01-01

    Novel fucoxanthin derivatives that could change the size of mixed micelles were synthesized. The mixed micelles under consideration consist of a bile acid and some additives. To change the affinity against a bile acid, we designed the synthesis of a fucoxanthin-lithocholic acid complex. Lithocholic acid is one of the bile acids. The 3-OH on lithocholic acid was protected by a levulinyl group, and the protected lithocholic acid was selectively coupled via an ester linkage to the 3-OH on fucoxanthin to obtain levulinyl-protected lithocholyl fucoxanthin (LevLF). The levulinyl group was then selectively deprotected using hydrazine to obtain a lithocholyl fucoxanthin (LF). The average sizes of the micelles that contained these compounds (fucoxanthin, LevLF, and LF) with a bile acid (sodium taurocholate) were measured. The LevLF induced larger micelles than fucoxanthin or LF. Interestingly, the addition of 1-oleoyl-rac-glycerol induced a more efficient change in the micelle size. The large micelles grew larger, and the small micelles became smaller. Triple-mixed micelles with LevLF, sodium taurocholate, and 1-oleoyl-rac-glycerol formed the largest micelle with a diameter of 68 nm. On the other hand, triple-mixed micelles using LF, sodium taurocholate, and 1-oleoyl-rac-glycerol made the smallest micelles with diameters as low as 12 nm. We also investigated the hydrolysis of these compounds with enzymes (esterase from porcine liver, lipase from porcine pancreas, and cholesterol esterase from Pseudomonas sp.). The ester linkage between the lithocholic acid and fucoxanthin of LevLF was hydrolyzed with cholesterol esterase. In addition, the intestinal absorption was examined with Caco-2 cells, and no advantageous change in absorption efficiency was observed by chemically modifying the fucoxanthin unless different micelles sizes and increasing hydrophobicity are induced. PMID:26250423

  18. Relevance of the OCT1 transporter to the antineoplastic effect of biguanides

    SciTech Connect

    Segal, Eric D.; Yasmeen, Amber; Beauchamp, Marie-Claude; Rosenblatt, Joshua; Segal Cancer Center, Lady Davis Institute of Medical Research, McGill University, Montreal, Quebec ; Pollak, Michael; Department of Oncology, McGill University, Montreal, Quebec ; Gotlieb, Walter H.

    2011-11-04

    Highlights: Black-Right-Pointing-Pointer siRNA knockdown of OCT1 reduced sensitivity of EOC cells to metformin, but not to another biguanide, phenformin. Black-Right-Pointing-Pointer Suppression of OCT1 also affects the activation of AMP kinase in response to metformin, but not to phenformin. Black-Right-Pointing-Pointer Direct actions of metformin may be limited by low OCT1 expression in EOC tumors. Black-Right-Pointing-Pointer Phenformin could be used as an alternative biguanide. -- Abstract: Epidemiologic and laboratory data suggesting that metformin has antineoplastic activity have led to ongoing clinical trials. However, pharmacokinetic issues that may influence metformin activity have not been studied in detail. The organic cation transporter 1 (OCT1) is known to play an important role in cellular uptake of metformin in the liver. We show that siRNA knockdown of OCT1 reduced sensitivity of epithelial ovarian cancer cells to metformin, but interestingly not to another biguanide, phenformin, with respect to both activation of AMP kinase and inhibition of proliferation. We observed that there is heterogeneity between primary human tumors with respect to OCT1 expression. These results suggest that there may be settings where drug uptake limits direct action of metformin on neoplastic cells, raising the possibility that metformin may not be the optimal biguanide for clinical investigation.

  19. Prenatal risks deriving from environmental chemicals.

    PubMed

    Mantovani, A; Ricciardi, C; Macr, C; Stazi, A V

    1993-01-01

    Hundreds of environmental chemicals affect prenatal development in experimental animals. However, only methylmercury and PCBs have been connected with such effects in humans during localized outbreaks of high exposure. In addition growth and development might also be affected by long-term intake of lead, fluorides or PCBs. Several factors may explain the discrepancy between human and animal data: the actual exposure of the population is below threshold levels, unspecific or delayed effects can be difficult to identify, etc. When experimental data are used to assess the hazards for the conceptus, due consideration should be given to actual ability of the study to detect effects. Thus, the limitations in statistical power, the relevance of the parameters considered and low-dose extrapolation should be taken into account. Finally, understanding toxicokinetics and biological mechanisms is needed to perform interspecies comparisons. Three examples of environmental chemicals showing different prenatal hazards are presented: thiabendazole, a benzimidazole compound with a moderate teratogenic potential, but which could represent a good model for biological extrapolation; nitrofen, a diphenyl ether herbicide which may pose a significant hazard, because of its high potential, toxicokinetics, and specific, hormone-like, teratogenic mechanisms; PCBs, well-known, global, cumulative pollutants which are not teratogenic in the laboratory animals, but may affect the human conceptus at high intake levels. PMID:8129272

  20. Therapeutic effects of biguanide vs. statin in polycystic ovary syndrome: a randomized clinical trial.

    PubMed

    Navali, Nazli; Pourabolghasem, Shabnam; Fouladi, Rohollah Fadaei; Nikpour, Mehri Amiri

    2011-06-01

    Various classes of medication are currently being used in Polycystic Ovary Syndrome (PCOS) patients including the biguanides and the statins. However, their efficacies are rarely compared. This study aimed to compare efficacy ofa biguanide and a statin in treating PCOS. In a randomized double-blind clinical trial, 400 women with PCOS were recruited within 15 months in Taleghani Hospital. They randomly received either a biguanide (metformin 500 mg three times daily) or a statin (simvastatin 20 mg daily) for three consecutive months. Changes of clinical and laboratory variables were compared. In the biguanide group the serum glucose status (abnormal fasting and non-fasting sugar and insulin levels and percentage of hyperinsulinemic cases) and menstrual abnormalities improved significantly after treatment (p < 0.05). In the statin group the lipid profile status (abnormal total cholesterol, high and low density lipoproteins), C-Reactive Protein (CRP), serum dehydroepiandrosterone sulfate, hyperinsulinemia, severity of acne and menstrual abnormalities improved significantly after treatment (p < 0.05). Comparing the two groups, the improvements in fasting blood sugar and serum insulin levels were significantly better in the biguanide group (p = 0.04 for both parameters); whereas the improvements in serum total cholesterol (p < 0.001), low density lipoprotein (p < 0.001), CRP (p < 0.001) and acne status (p = 0.04) were significantly superior in the statin receivers. Based on these results, each medication is only effective on some aspects of the disease. Overall, the simvastatin was superior to metformin with regard to the number of beneficial effects. PMID:22235508

  1. Revisiting the chemical reactivity indices as the state function derivatives. The role of classical chemical hardness

    SciTech Connect

    Malek, Ali; Balawender, Robert

    2015-02-07

    The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor.

  2. Evaluation of novel lactone derivatives for chemically amplified EUV resists

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroyasu; Mizusaka, Tetsuhiko; Tanagi, Hiroyuki; Furukawa, Kikuo; Yamamoto, Hiroki; Kozawa, Takahiro

    2015-03-01

    EUV lithography is the most favorable process for high volume manufacturing of semiconductor devices beyond 1X nm half-pitch at present. Many efforts have revealed effective proton sources in acid generation in EUV resists, and the effective proton generation and the control of the generated acid diffusion are required to improve the breakthrough of the resolution ? line width roughness ? sensitivity(RLS) trade-off. To clarify the lithographic performance of these derivatives, we synthesized the acrylic ter/tetrapolymers containing novel lactone derivatives - LCHO and LAATB - as model photopolymers and exposed the resist samples based on these polymers to EUV and EB radiation. On the basis of the lithographic performances of these photoresists, we evaluated the characteristics of lactone derivatives upon exposure to EUV radiation. We discuss the relationship between the chemical structures of these derivatives and lithographic performance.

  3. Evaluation of novel hydrophilic derivatives for chemically amplified EUV resists

    NASA Astrophysics Data System (ADS)

    Tanagi, Hiroyuki; Tanaka, Hiroyasu; Hayakawa, Shoichi; Furukawa, Kikuo; Yamamoto, Hiroki; Kozawa, Takahiro

    2014-03-01

    EUV lithography is the most favorable process for high volume manufacturing of semiconductor devices beyond 1X nm half-pitch. Many efforts have revealed effective proton sources in acid generation in EUV resists, and the effective proton generation and the control of the generated acid diffusion are required to improve the breakthrough of the resolution ? line width roughness ? sensitivity(RLS) trade-off. To clarify the lithographic performance of these derivatives, we synthesized the acrylic terpolymers containing novel hydrophilic derivatives as model photopolymers and exposed the resist samples based on these polymers to EUV and EB radiation. On the basis of the lithographic performances of these resist samples, we evaluated the characteristics of hydrophilic derivatives upon exposure to EUV radiation. We discuss the relationship between the chemical structures of these derivatives and lithographic performance.

  4. Study on resist performance of chemically amplified molecular resist based on noria derivative and calixarene derivative

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hiroki; Kudo, Hiroto; Kozawa, Takahiro

    2014-03-01

    Novel resist materials are required for lithographic processing with ionization radiation such as extreme ultraviolet (EUV) and electron beam (EB) exposure tool. In this study, we developed positive-tone chemically amplified molecular resists based on noria derivatives and calixarene derivatives and evaluated the lithographic performance using EUV and EB. We make clear that a small change in modification of noria resists can cause a significant change of sensitivity. Especially, it is useful for the improvement of resist sensitivities to use protecting groups such as 2-acetyloxy-2-methyladamantyl ester (AD) groups and ethoxy groups. Also, novel calixarene derivative such as pillar[5]arene protected by AD showed a semi-isolated pattern with the line width of 40 nm (pitch: 100nm). Noria derivatives and calixarene derivative resists were promising candidates because of high sensitivity, high resolution and etch durability similar to conventional resist such as ZEP 520A and UVIII.

  5. Biological activity of oleanane triterpene derivatives obtained by chemical derivatization.

    PubMed

    Cheng, Shi-Yie; Wang, Chao-Min; Cheng, Hsueh-Ling; Chen, Hui-Jye; Hsu, Yuan-Man; Lin, Yu-Chi; Chou, Chang-Hung

    2013-01-01

    Nine new derivatives of oleanane triterpenoids isolated from Fatsia polycarpa Hayata were synthesized through chemical transformations. Acetylation was effected by reaction with acetic anhydride in pyridine to afford compounds 1-5, while compound 6 was obtained using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCHCl) in CH2Cl2. The others derivatives 7-9 were obtained in reactions of the corresponding triterpenoids with EDCHCl, 4-N,N-dimethylaminopyridine hydrochloride and 4-N,N-dimethylaminopyridine in CH2Cl2. The structures of 1-9 were elucidated from extensive spectroscopic and HRESIMS data, while the structure of 9 was further confirmed by X-ray diffraction analysis. The cytotoxic, anti-hepatitis B virus (HBV), antibacterial, hypoglycaemic and Wnt signaling activities of these derivatives were evaluated in vitro. PMID:24145793

  6. Analytical Derivation of Moment Equations in Stochastic Chemical Kinetics

    PubMed Central

    Sotiropoulos, Vassilios; Kaznessis, Yiannis N.

    2011-01-01

    The master probability equation captures the dynamic behavior of a variety of stochastic phenomena that can be modeled as Markov processes. Analytical solutions to the master equation are hard to come by though because they require the enumeration of all possible states and the determination of the transition probabilities between any two states. These two tasks quickly become intractable for all but the simplest of systems. Instead of determining how the probability distribution changes in time, we can express the master probability distribution as a function of its moments, and, we can then write transient equations for the probability distribution moments. In 1949, Moyal defined the derivative, or jump, moments of the master probability distribution. These are measures of the rate of change in the probability distribution moment values, i.e. what the impact is of any given transition between states on the moment values. In this paper we present a general scheme for deriving analytical moment equations for any N-dimensional Markov process as a function of the jump moments. Importantly, we propose a scheme to derive analytical expressions for the jump moments for any N-dimensional Markov process. To better illustrate the concepts, we focus on stochastic chemical kinetics models for which we derive analytical relations for jump moments of arbitrary order. Chemical kinetics models are widely used to capture the dynamic behavior of biological systems. The elements in the jump moment expressions are a function of the stoichiometric matrix and the reaction propensities, i.e the probabilistic reaction rates. We use two toy examples, a linear and a non-linear set of reactions, to demonstrate the applicability and limitations of the scheme. Finally, we provide an estimate on the minimum number of moments necessary to obtain statistical significant data that would uniquely determine the dynamics of the underlying stochastic chemical kinetic system. The first two moments only provide limited information, especially when complex, non-linear dynamics are involved. PMID:21949443

  7. Biguanide-functionalized mesoporous SBA-15 silica as an efficient solid catalyst for interesterification of vegetable oils.

    PubMed

    Xie, Wenlei; Hu, Libing

    2016-04-15

    The biguanide-functionalized SBA-15 materials were fabricated by grafting of organic biguanide onto the SBA-15 silica through covalent attachments, and then this organic-inorganic hybrid material was employed as solid catalysts for the interesterification of triacylglycerols for the modification of vegetable oils. The prepared catalyst was characterized by FTIR, XRD, SEM, TEM, nitrogen adsorption-desorption and elemental analysis. The biguanide base was successfully tethered onto the SBA-15 silica with no damage to the ordered mesoporous structure of the silica after the organo-functionalization. The solid catalyst had stronger base strength and could catalyze the interesterification of triacylglycerols. The fatty acid compositions and triacylglycerol profiles of the interesterified products were noticeably varied following the interesterification. The reaction parameters, namely substrate ratio, reaction temperature, catalyst loading and reaction time, were investigated for the interesterification of soybean oil with methyl decanoate. The catalyst could be reused for at least four cycles without significant loss of activity. PMID:26616928

  8. The biguanides metformin and phenformin inhibit angiogenesis, local and metastatic growth of breast cancer by targeting both neoplastic and microenvironment cells.

    PubMed

    Orecchioni, Stefania; Reggiani, Francesca; Talarico, Giovanna; Mancuso, Patrizia; Calleri, Angelica; Gregato, Giuliana; Labanca, Valentina; Noonan, Douglas M; Dallaglio, Katiuscia; Albini, Adriana; Bertolini, Francesco

    2015-03-15

    The human white adipose tissue (WAT) contains progenitors with cooperative roles in breast cancer (BC) angiogenesis, local and metastatic progression. The biguanide Metformin (Met), commonly used for Type 2 diabetes, might have activity against BC and was found to inhibit angiogenesis in vivo. We studied Met and another biguanide, phenformin (Phe), in vitro and in vivo in BC models. In vitro, biguanides activated AMPK, inhibited Complex 1 of the respiratory chain and induced apoptosis of BC and WAT endothelial cells. In coculture, biguanides inhibited the production of several angiogenic proteins. In vivo, biguanides inhibited local and metastatic growth of triple negative and HER2+ BC in immune-competent and immune-deficient mice orthotopically injected with BC. Biguanides inhibited local and metastatic BC growth in a genetically engineered murine model model of HER2+ BC. In vivo, biguanides increased pimonidazole binding (but not HIF-1 expression) of WAT progenitors, reduced tumor microvessel density and altered the vascular pericyte/endothelial cell ratio, so that cancer vessels displayed a dysplastic phenotype. Phe was significantly more active than Met both in vitro and in vivo. Considering their safety profile, biguanides deserve to be further investigated for BC prevention in high-risk subjects, in combination with chemo and/or targeted therapy and/or as post-therapy consolidation or maintenance therapy for the prevention of BC recurrence. PMID:25196138

  9. Metabolic determinants of cancer cell sensitivity to glucose limitation and biguanides

    NASA Astrophysics Data System (ADS)

    Birsoy, K?van; Possemato, Richard; Lorbeer, Franziska K.; Bayraktar, Erol C.; Thiru, Prathapan; Yucel, Burcu; Wang, Tim; Chen, Walter W.; Clish, Clary B.; Sabatini, David M.

    2014-04-01

    As the concentrations of highly consumed nutrients, particularly glucose, are generally lower in tumours than in normal tissues, cancer cells must adapt their metabolism to the tumour microenvironment. A better understanding of these adaptations might reveal cancer cell liabilities that can be exploited for therapeutic benefit. Here we developed a continuous-flow culture apparatus (Nutrostat) for maintaining proliferating cells in low-nutrient media for long periods of time, and used it to undertake competitive proliferation assays on a pooled collection of barcoded cancer cell lines cultured in low-glucose conditions. Sensitivity to low glucose varies amongst cell lines, and an RNA interference (RNAi) screen pinpointed mitochondrial oxidative phosphorylation (OXPHOS) as the major pathway required for optimal proliferation in low glucose. We found that cell lines most sensitive to low glucose are defective in the OXPHOS upregulation that is normally caused by glucose limitation as a result of either mitochondrial DNA (mtDNA) mutations in complex I genes or impaired glucose utilization. These defects predict sensitivity to biguanides, antidiabetic drugs that inhibit OXPHOS, when cancer cells are grown in low glucose or as tumour xenografts. Notably, the biguanide sensitivity of cancer cells with mtDNA mutations was reversed by ectopic expression of yeast NDI1, a ubiquinone oxidoreductase that allows bypass of complex I function. Thus, we conclude that mtDNA mutations and impaired glucose utilization are potential biomarkers for identifying tumours with increased sensitivity to OXPHOS inhibitors.

  10. Metabolic determinants of cancer cell sensitivity to glucose limitation and biguanides

    PubMed Central

    Birsoy, K?van; Possemato, Richard; Lorbeer, Franziska K.; Bayraktar, Erol C.; Thiru, Prathapan; Yucel, Burcu; Wang, Tim; Chen, Walter W.; Clish, Clary B.; Sabatini, David M.

    2014-01-01

    As the concentrations of highly consumed nutrients, particularly glucose, are generally lower in tumours than in normal tissues1,2, cancer cells must adapt their metabolism to the tumour microenvironment. A better understanding of these adaptations might reveal cancer cell liabilities that can be exploited for therapeutic benefit. Here, we developed a continuous flow culture apparatus (Nutrostat) for maintaining proliferating cells in low nutrient media for long periods of time and used it to undertake competitive proliferation assays on a pooled collection of barcoded cancer cell lines cultured in low glucose conditions. Sensitivity to low glucose varies amongst cell lines, and an RNAi screen pinpointed mitochondrial oxidative phosphorylation (OXPHOS) as the major pathway required for optimal proliferation in low glucose. We found that cell lines most sensitive to low glucose are defective in the upregulation of OXPHOS normally caused by glucose limitation as a result of either mtDNA mutations in Complex I genes or impaired glucose utilization. These defects predict sensitivity to biguanides, anti-diabetic drugs that inhibit OXPHOS3,4, when cancer cells are grown in low glucose or as tumour xenografts. Remarkably, the biguanide sensitivity of cancer cells with mtDNA mutations was reversed by ectopic expression of yeast NDI1, a ubiquinone oxidoreductase that allows bypass of Complex I function5. Thus, we conclude that mtDNA mutations and impaired glucose utilization are potential biomarkers for identifying tumours with increased sensitivity to OXPHOS inhibitors. PMID:24670634

  11. Deriving uncertainty factors for threshold chemical contaminants in drinking water.

    PubMed

    Ritter, Leonard; Totman, Céline; Krishnan, Kannan; Carrier, Richard; Vézina, Anne; Morisset, Véronique

    2007-10-01

    Uncertainty factors are used in the development of drinking-water guidelines to account for uncertainties in the database, including extrapolations of toxicity from animal studies and variability within humans, which result in some uncertainty about risk. The application of uncertainty factors is entrenched in toxicological risk assessment worldwide, but is not applied consistently. This report, prepared in collaboration with Health Canada, provides an assessment of the derivation of the uncertainty factor assumptions used in developing drinking-water quality guidelines for chemical contaminants. Assumptions used by Health Canada in the development of guidelines were compared to several other major regulatory jurisdictions. This assessment has revealed that uncertainty factor assumptions have been substantially influenced by historical practice. While the application of specific uncertainty factors appears to be well entrenched in regulatory practice, a well-documented and disciplined basis for the selection of these factors was not apparent in any of the literature supporting the default assumptions of Canada, the United States, Australia, or the World Health Organization. While there is a basic scheme used in most cases in developing drinking-water quality guidelines for nonthreshold contaminants by the jurisdictions included in this report, additional factors are sometimes included to account for other areas of uncertainty. These factors may include extrapolating subchronic data to anticipated chronic exposure, or use of a LOAEL instead of a NOAEL. The default value attributed to each uncertainty factor is generally a factor of 3 or 10; however, again, no comprehensive guidance to develop and apply these additional uncertainty factors was evident from the literature reviewed. A decision tree has been developed to provide guidance for selection of appropriate uncertainty factors, to account for the range of uncertainty encountered in the risk assessment process. Recent development of a series of "decision trees" by WHO to derive chemical specific adjustment factors for inter- and intraspecies variability may present an opportunity for a more systematic approach for the identification of evidence-based uncertainty factors. PMID:17934949

  12. Unique marine derived cyanobacterial biosynthetic genes for chemical diversity.

    PubMed

    Kleigrewe, Karin; Gerwick, Lena; Sherman, David H; Gerwick, William H

    2016-02-01

    Covering: 2010 to July 2015. Previous review: Nat. Prod. Rep., 2010, 27, 1048-1065Cyanobacteria are a prolific source of structurally unique and biologically active natural products that derive from intriguing biochemical pathways. Advancements in genome sequencing have accelerated the identification of unique modular biosynthetic gene clusters in cyanobacteria and reveal a wealth of unusual enzymatic reactions involved in their construction. This article examines several interesting mechanistic transformations involved in cyanobacterial secondary metabolite biosynthesis with a particular focus on marine derived modular polyketide synthases (PKS), nonribosomal peptide synthetases (NRPS) and combinations thereof to form hybrid natural products. Further, we focus on the cyanobacterial genus Moorea and the co-evolution of its enzyme cassettes that create metabolic diversity. Progress in the development of heterologous expression systems for cyanobacterial gene clusters along with chemoenzymatic synthesis makes it possible to create new analogs. Additionally, phylum-wide genome sequencing projects have enhanced the discovery rate of new natural products and their distinctive enzymatic reactions. Summarizing, cyanobacterial biosynthetic gene clusters encode for a large toolbox of novel enzymes that catalyze unique chemical reactions, some of which may be useful in synthetic biology. PMID:26758451

  13. Physical and chemical characterization of waste wood derived biochars.

    PubMed

    Yargicoglu, Erin N; Sadasivam, Bala Yamini; Reddy, Krishna R; Spokas, Kurt

    2015-02-01

    Biochar, a solid byproduct generated during waste biomass pyrolysis or gasification in the absence (or near-absence) of oxygen, has recently garnered interest for both agricultural and environmental management purposes owing to its unique physicochemical properties. Favorable properties of biochar include its high surface area and porosity, and ability to adsorb a variety of compounds, including nutrients, organic contaminants, and some gases. Physical and chemical properties of biochars are dictated by the feedstock and production processes (pyrolysis or gasification temperature, conversion technology and pre- and post-treatment processes, if any), which vary widely across commercially produced biochars. In this study, several commercially available biochars derived from waste wood are characterized for physical and chemical properties that can signify their relevant environmental applications. Parameters characterized include: physical properties (particle size distribution, specific gravity, density, porosity, surface area), hydraulic properties (hydraulic conductivity and water holding capacity), and chemical and electrochemical properties (organic matter and organic carbon contents, pH, oxidation-reduction potential and electrical conductivity, zeta potential, carbon, nitrogen and hydrogen (CHN) elemental composition, polycyclic aromatic hydrocarbons (PAHs), heavy metals, and leachable PAHs and heavy metals). A wide range of fixed carbon (0-47.8%), volatile matter (28-74.1%), and ash contents (1.5-65.7%) were observed among tested biochars. A high variability in surface area (0.1-155.1g/m(2)) and PAH and heavy metal contents of the solid phase among commercially available biochars was also observed (0.7-83 mg kg(-1)), underscoring the importance of pre-screening biochars prior to application. Production conditions appear to dictate PAH content--with the highest PAHs observed in biochar produced via fast pyrolysis and lowest among the gasification-produced biochars. PMID:25464942

  14. Mucoadhesive system formed by liquid crystals for buccal administration of poly(hexamethylene biguanide) hydrochloride.

    PubMed

    Souza, Carla; Watanabe, Evandro; Borgheti-Cardoso, Livia Neves; De Abreu Fantini, Márcia Carvalho; Lara, Marilisa Guimarães

    2014-12-01

    Antimicrobial approaches are valuable in controlling the development of buccal diseases, but some antibacterial agents have a short duration of activity. Therefore, the development of prolonged delivery systems would be advantageous. Liquid crystalline systems comprising monoolein (GMO)/water have been considered to be a potential vehicle to deliver drugs to the buccal mucosa because of the phase properties that allow for controlled drug release as well as its mucoadhesive properties. Therefore, the aim of this study was to develop a GMO/water system for the slow release of poly(hexamethylene biguanide) hydrochloride (PHMB) on the buccal mucosa and test the properties of this system with regard to swelling, release profile, antimicrobial activity, and strength of mucoadhesion, with the overall goal of treating buccal infections. The tested systems were capable of modulating drug release, which is controlled by diffusion of the drug throughout the system. Furthermore, PHMB appeared to improve the mucoadhesive properties of the system and may synergistically act with the drug to promote antimicrobial activity against S. mutas and C. albicans, indicating that liquid crystals may be suitable for the administration of PHMB on the buccal mucosa. Therefore, this system could be proposed as a novel system for mucoadhesive drug delivery. PMID:25336429

  15. Effects of Polyhexamethylene Biguanide and Polyquaternium-1 on Phospholipid Bilayer Structure and Dynamics.

    PubMed

    Horner, Ian J; Kraut, Nadine D; Hurst, Jerod J; Rook, Alyssa M; Collado, Crystal M; Atilla-Gokcumen, G Ekin; Maziarz, E Peter; Liu, X Michael; Merchea, Mohinder M; Bright, Frank V

    2015-08-20

    Multipurpose solutions (MPS) are a single solution that functions to simultaneously rinse, disinfect, clean, and store soft contact lenses. Several commercial MPS products contain polyhexamethylene biguanide (PHMB) and/or polyquaternium-1 (PQ-1) as antimicrobial agents. In this paper we have created an in vitro small unilamellar vesicle (SUV) model of the corneal epithelial surface, and we have assessed the interactions of PHMB and PQ-1 with several model biomembranes by using fluorescence spectroscopy, dynamic light scattering (DLS), and liquid chromatography-mass spectrometry (LC-MS). Steady-state and time-resolved fluorescence were used to assess the membrane acyl chain and polar headgroup region local microenvironment as a function of added PHMB or PQ-1. DLS was used to detect and quantify SUV aggregation induced by PHMB and PQ-1. LC-MS was used to determine the liposomal composition from any precipitated materials in comparison to the as-prepared SUVs. The results are consistent with PHMB adsorbing onto and PQ-1 intercalating into the biomembrane structure. The differences between the two interaction mechanisms have substantial impacts on the biomembrane dynamics and stability. PMID:26239890

  16. Antimicrobial electrospun membranes of chitosan/poly(ethylene oxide) incorporating poly(hexamethylene biguanide) hydrochloride.

    PubMed

    Dilamian, M; Montazer, M; Masoumi, J

    2013-04-15

    Here, antimicrobial nanofibrous membranes were produced by electrospinning of chitosan/poly(ethylene oxide) (PEO) solution in the presence of poly(hexamethylene biguanide) hydrochloride (PHMB). The influence of PHMB on the electrospinnability and antimicrobial properties of chitosan/PEO nanofibers were studied. Further, viscosity of the solutions as well as morphology of the nanofibrous structures were investigated. Results revealed that incorporation of PHMB in chitosan/PEO solutions led to decrease in the zero-shear rate viscosity up to 20%. Moreover, increasing PHMB from 0.5 mM to 1 mM led to formation of thinner fibers with diameters ranging from 240 nm to 60 nm, respectively. Fourier transform infrared (FT-IR) spectrums indicated the functional groups of chitosan, PEO and PHMB in nanofibrous structure. Differential scanning calorimetry (DSC) thermograms indicated interaction of PHMB with PEO and chitosan through alteration in the thermal behavior of the nanofibers. Inhibition of the bacteria growth for both Escherichia coli and Staphylococcus aureus were achieved on the PHMB loaded nanofibers. Also, a burst release of PHMB from mats has been observed in the first hour. These findings suggest that there is a great potential in fabrication of biomaterials with incorporation of PHMB using electrospinning. PMID:23544550

  17. Is it time to test biguanide metformin in the treatment of melanoma?

    PubMed

    Cerezo, Michael; Tomic, Tijana; Ballotti, Robert; Rocchi, Stphane

    2015-01-01

    Metformin is the most widely used antidiabetic drug that belongs to the biguanide class. It is very well tolerated and has the major clinical advantage of not inducing hypoglycemia. Metformin decreases hepatic glucose production via a mechanism requiring liver kinase B1, which controls the metabolic checkpoint, AMP-activated protein kinase-mammalian target of rapamycin and neoglucogenic genes. The effects of metformin on this pathway results in reduced protein synthesis and cell proliferation. These observations have given the impetus for many investigations on the role of metformin in the regulation of tumor cell proliferation, cell-cycle regulation, apoptosis, and autophagy. Encouraging results from these studies have shown that metformin could potentially be used as an efficient anticancer drug in various neoplasms such as prostate, breast, lung, pancreas cancers, and melanoma. These findings are strengthened by retrospective epidemiological studies that have found a decrease in cancer risk in diabetic patients treated with metformin. In this review, we have focused our discussion on recent molecular mechanisms of metformin that have been described in various solid tumors in general and in melanoma in particular. PMID:24862830

  18. Iodine derivatives of chemically modified gum Arabic microspheres.

    PubMed

    Ganie, Showkat A; Ali, Akbar; Mazumdar, Nasreen

    2015-09-20

    Acetylated gum Arabic (AGA) derivatives with different degrees of substitution (DS 0.97-2.74) were synthesized using acetyl chloride and a base under varying reaction conditions. The AGA derivatives were obtained in the form of microspheres and thereafter stable iodine products were prepared by doping the microspheres with an iodinating agent, iodine monochloride (ICl). The reaction between electrophilic iodine and polar carbonyl groups was studied by FT-IR, (1)H-NMR, and UV-VIS spectroscopies. The products were also characterized by DSC, TGA and SEM studies. The incorporated iodine was released in aqueous medium as iodide ions (I(-)). A reaction scheme has been proposed for the iodination and de-iodination of the gum derivatives. This work suggests that the iodine derivatives of modified gum Arabic could be used as a source of iodide ions which is the nutritional form of iodine. PMID:26050909

  19. Coumarin heterocyclic derivatives: chemical synthesis and biological activity.

    PubMed

    Medina, Fernanda G; Marrero, Joaqun G; Macas-Alonso, Mariana; Gonzlez, Magdalena C; Crdova-Guerrero, Ivn; Teissier Garca, Ariana G; Osegueda-Robles, Soraya

    2015-09-23

    This review highlights the broad range of science that has arisen from the synthesis of coumarin-linked and fused heterocycle derivatives. Specific topics include their synthesis and biological activity. PMID:26151411

  20. Opinion of the scientific committee on consumer safety (SCCS) - 2nd Revision of the safety of the use of poly(hexamethylene) biguanide hydrochloride or polyaminopropyl biguanide (PHMB) in cosmetic products.

    PubMed

    Bernauer, Ulrike

    2015-12-01

    Conclusion of the opinion: On the basis of the data available, the SCCS concludes that Polyaminopropyl Biguanide (PHMB) is not safe for consumers when used as a preservative in cosmetic spray formulations and in all cosmetic products up to the maximum concentration of 0.3%. The safe use could be based on a lower use concentration and/or restrictions with regard to cosmetic products' categories. Dermal absorption studies on additional representative cosmetic formulations are needed. PHMB is used in a variety of applications other than cosmetics. General exposure data from sources others than cosmetics should be submitted for the assessment of the aggregate exposure of PHMB. PMID:26456666

  1. The Evaluation of Polyhexamethylene Biguanide (PHMB) as a Disinfectant for Adenovirus

    PubMed Central

    Romanowski, Eric G.; Yates, Kathleen A.; O’Connor, Katherine E.; Mah, Francis S.; Shanks, Robert M. Q.; Kowalski, Regis P.

    2013-01-01

    Purpose Swimming pools can be a vector for transmission of adenovirus ocular infections. Polyhexamethylene biguanide (PHMB) is a disinfectant used in swimming pools and hot tubs. The current study determined whether PHMB is an effective disinfectant against ocular adenovirus serotypes at a concentration used to disinfect swimming pools and hot tubs. Methods The direct disinfecting activity of PHMB was determined in triplicate assays by incubating nine human adenovirus types (1, 2, 3, 4, 5, 7a, 8, 19, and 37) with 50 and 0 PPM (µg/ml) of PHMB for 24 hours at room temperature, to simulate swimming pool temperatures, or 40°C, to simulate hot tub temperatures. Plaque assays determined adenovirus titers after incubation. Titers were Log10 converted and mean ± standard deviation Log10 reductions from controls were calculated. Virucidal (greater than 99.9%) decreases in mean adenovirus titers after PHMB treatment were determined for each adenovirus type and temperature tested. Results At room temperature, 50 PPM of PHMB produced mean reductions in titers less than 1 Log10 for all adenovirus types tested. At 40°C, 50 PPM of PHMB produced mean reductions in titers less than 1 Log10 for two adenovirus types and greater than 1 Log10, but less than 3 Log10, for seven of nine adenovirus types. Conclusions 50 PPM of PHMB was not virucidal against adenovirus at temperatures consistent with swimming pools or hot tubs. Clinical Relevance Recreational water maintained and sanitized with PHMB has the potential to serve as a vector for the transmission of ocular adenovirus infections. PMID:23450376

  2. Microbial production of fatty acid-derived fuels and chemicals

    PubMed Central

    Lennen, Rebecca M; Pfleger, Brian F

    2013-01-01

    Fatty acid metabolism is an attractive route to produce liquid transportation fuels and commodity oleochemicals from renewable feedstocks. Recently, genes and enzymes, which comprise metabolic pathways for producing fatty acid-derived compounds (e.g. esters, alkanes, olefins, ketones, alcohols, polyesters) have been elucidated and used in engineered microbial hosts. The resulting strains often generate products at low percentages of maximum theoretical yields, leaving significant room for metabolic engineering. Economically viable processes will require strains to approach theoretical yields, particularly for replacement of petroleum-derived fuels. This review will describe recent progress toward this goal, highlighting the scientific discoveries of each pathway, ongoing biochemical studies to understand each enzyme, and metabolic engineering strategies that are being used to improve strain performance. PMID:23541503

  3. Chemical applications of neural networks: aromaticity of pyrimidine derivatives.

    PubMed

    Alonso, Mercedes; Miranda, Carlos; Martín, Nazario; Herradón, Bernardo

    2011-12-14

    Neural networks are computational tools able to apprehend non-linear relationships between different parameters, having the capacity to order a large amount of input data and transform them into a graphical pattern of output data. We have previously reported their use for the quantification of the aromaticity through the Euclidean distance between neurons. In this article, we apply the method to a variety of pyrimidine derivatives with electron-donor and electron-withdrawing groups as substituents, with capacity to produce push-pull compounds. We have calculated the aromaticity of benzene (as a reference molecule), parent pyrimidine and other 11 pyrimidine derivatives having amino, dimethylamino and tricyanovinyl substitution. The neural network has been generated using ASE, Λ, NICS(zz)(1) and HOMA as aromaticity descriptors, since our previous work showed that the combination of these indices provided the best performance of the network. On studying the influence of the substituent on the aromaticity of the molecule, we have found that, opposite to benzene derivatives, all the substituents decrease the aromaticity of the ring. The interplay between aromaticity, planarity and push-pull properties of all the substituted pyrimidines has also been addressed. An interesting feature of the neural network to quantify aromaticity is that the importance of the reference reaction used to evaluate energy stabilization and magnetic susceptibility exaltation is minimized. PMID:21879068

  4. Polo and Aurora kinases: lessons derived from chemical biology.

    PubMed

    Taylor, Stephen; Peters, Jan-Michael

    2008-02-01

    During the cell division cycle, mitotic entry, spindle assembly, chromosome segregation, and cytokinesis must all be carefully coordinated to ensure that the two daughter cells inherit all the genetic material required for further growth and development. Central to this coordination are several protein kinases including Aurora A, Aurora B, and the Polo-like kinase, Plk1. A number of small-molecule Aurora and Plk1 inhibitors have been developed because these kinases are seen as attractive anticancer drug targets. These inhibitors are now being widely used as chemical biology tools to understand how these kinases ensure faithful genome transmission. PMID:18249108

  5. Biological and chemical diversity of coral-derived microorganisms.

    PubMed

    Hou, Xue-Mei; Xu, Ru-Fang; Gu, Yu-Cheng; Wang, Chang-Yun; Shao, Chang-Lun

    2015-01-01

    Coral-derived microorganisms have been a major focus of many research efforts on marine ecology in recent decades. Importantly, research on bioactive compounds from these diverse microorganisms, which include fungi and bacteria, has experienced an explosive growth during the past five years. This has unveiled the ecological roles of these microorganisms, which prevent antifouling, inhibit pathogenic bacteria, and deter predators in ocean ecosystems. Moreover, the structural diversity and pharmacological activity of the compounds produced by these microorganisms have also been studied extensively, leading not only to an understanding their roles within ecosystems, but also the potential value of their use in human health. In this review, 258 marine natural products, including polyketides, terpenoids, meroterpenoids, alkaloids, peptides, shikimates and lipids, all discovered in the past 24 years, are presented. 146 references are cited. PMID:26438250

  6. Photovoltaic Study of Chemically Derived Titanium-Doped Polythiophene Composites

    NASA Astrophysics Data System (ADS)

    Takpire, S. R.; Waghuley, S. A.

    2015-08-01

    In the present work, titanium (Ti)-doped polythiophene (PTh) was synthesized by a chemical route using titanium chloride as oxidant. As-synthesized composites were further used for fabrication of photovoltaic (PV) cells with indium tin oxide/Ti-doped PTh/aluminum architecture. Structural, morphological, and optical analyses of as-synthesized composites were carried out through x-ray diffraction (XRD) analysis, Fourier-transform infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), ultraviolet-visible (UV-Vis) spectroscopy, and photoluminescence (PL) measurements. A broad peak was found in the PL spectra of the composites at around 480 nm, indicating high charge generation efficiency. Different PV parameters of the fabricated PV cells were measured at room temperature under incandescent light of 100 W/m2. The optimized PV cell exhibited short-circuit current ( I sc) and open-circuit voltage ( V oc) on the order of 176 ?A and 0.595 V, respectively. The values of I sc and V oc were used to compute the fill factor, which was found to be 0.521. The corresponding power conversion efficiency associated with the optimized cell was found to be 2.41%.

  7. Tendencies of 31P chemical shifts changes in NMR spectra of nucleotide derivatives.

    PubMed

    Lebedev, A V; Rezvukhin, A I

    1984-07-25

    31P NMR chemical shifts of the selected mono- and oligonucleotide derivatives, including the compounds with P-N, P-C, P-S bonds and phosphite nucleotide analogues have been presented. The influence of substituents upon 31P chemical shifts has been discussed. The concrete examples of 31P chemical shifts data application in the field of nucleotide chemistry have been considered. PMID:6087290

  8. Chemical equilibrium. [maximizing entropy of gas system to derive relations between thermodynamic variables

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The entropy of a gas system with the number of particles subject to external control is maximized to derive relations between the thermodynamic variables that obtain at equilibrium. These relations are described in terms of the chemical potential, defined as equivalent partial derivatives of entropy, energy, enthalpy, free energy, or free enthalpy. At equilibrium, the change in total chemical potential must vanish. This fact is used to derive the equilibrium constants for chemical reactions in terms of the partition functions of the species involved in the reaction. Thus the equilibrium constants can be determined accurately, just as other thermodynamic properties, from a knowledge of the energy levels and degeneracies for the gas species involved. These equilibrium constants permit one to calculate the equilibrium concentrations or partial pressures of chemically reacting species that occur in gas mixtures at any given condition of pressure and temperature or volume and temperature.

  9. Deriving chemical trends from thermal infrared spectra of weathered basalt: Implications for remotely determining chemical trends on Mars

    NASA Astrophysics Data System (ADS)

    Rampe, Elizabeth B.; Kraft, Michael D.; Sharp, Thomas G.

    2013-07-01

    Variations in chemical composition over a planetary surface can be used to study petrologic and aqueous alteration processes. The desire for such data on Mars has prompted investigators to derive chemistry from models of Thermal Emission Spectrometer data. Although chemistry derived from thermal infrared spectral models is reportedly reliable for unaltered igneous rocks, the martian surface has experienced chemical weathering, which can adversely affect models. Here, we examine weathered basalts from Baynton, Australia, for which chemical weathering trends have been previously characterized, to test how well chemistry and chemical trends can be determined from TIR spectra of weathered rocks. The mineralogy of variably weathered rocks was derived from TIR spectra by linear mixing, and major-element chemistry was calculated from those mineral models. Derived chemistries and trends were compared to those measured by X-ray fluorescence. TIR spectroscopy is sensitive to weathering products in weathering rinds because the products are present in a coating geometry, making it a useful technique for remotely detecting weathered surfaces on planetary surfaces such as Mars. This sensitivity results in significant modeled abundances of weathering products (>80% of all phases) from TIR spectra of weathered Baynton surfaces, despite evidence from microscopy and X-ray diffraction showing that igneous minerals dominate the weathering rind. Measured chemical weathering trends show loss of MgO, CaO, Na2O, and K2O and relative enrichment in Al2O3 and FeOT. The modeled trends are similar to the measured trends, but a closer look at the modeled oxide abundances demonstrates that most oxides (i.e., alkalis, SiO2, and FeOT) are not well modeled, especially for weathered surfaces. The reasons for this are: (1) non-linear mixing and the presence of secondary coatings causes the overestimation of secondary phases in spectral models, and (2) spectral libraries generally lack poorly crystalline and amorphous secondary phases that are common in weathering rinds so that crystalline phases such as phyllosilicates are selected. The martian surface has likely been weathered less pervasively than the Baynton rocks and, therefore, weathering products may be dominated by poorly crystalline and amorphous phases, rather than crystalline phyllosilicates. Adding these phases to spectral libraries could improve bulk chemistry derived from the martian surface; however, if the secondary phases are present in a coating geometry, the derived chemistry will reflect the composition of the coating, and it may be difficult to infer the chemistry of the parent rock.

  10. Development of novel protecting derivatives for chemically amplified extreme ultraviolet resist

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroyasu; Tanagi, Hiroyuki; Hayakawa, Shoichi; Furukawa, Kikuo; Yamamoto, Hiroki; Kozawa, Takahiro

    2014-03-01

    EUV lithography is the most favorable process for high volume manufacturing of semiconductor devices below 1X nm half-pitch. Many efforts have revealed that the effective proton generation and the control of the generated acid diffusion are required to improve the breakthrough of the RLS trade-off. For the development of EUV resists, the novel protecting derivatives were designed. To clarify the lithographic performance of these derivatives, we synthesized the acrylic polymers containing these derivatives as model photopolymers and exposed the resist samples based on these polymers to EUV/EB radiation. On the basis of the lithographic performances of these resist sample, we evaluated the characteristics of novel protecting derivatives upon exposure to EUV/EB radiation. We discuss the relationship between the chemical structures of these derivatives and lithographic performance.

  11. Gram-positive bacteria as biocatalysts to convert biomass derived sugars into biofuel and chemicals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The microbial fermentation of biomass derived sugar mixtures is one of the barriers to the overall economic conversion process from lignocellulosic biomass to fuels and chemicals. Although the supply and characteristics of feedstocks vary, biomass hydrolysates usually contain mixed sugars, organic ...

  12. Synthesis and applications of 2-aminopyrimidine derivatives as key intermediates in chemical synthesis of biomolecules

    NASA Astrophysics Data System (ADS)

    Koroleva, Elena V.; Gusak, K. N.; Ignatovich, Zh V.

    2010-10-01

    Published data on the main approaches to the formation of the heterocyclic 2-aminopyrimidine system, which is one of important pharmacophores responsible for the biological properties of its derivatives, are described systematically. Main chemical transformations of functionalized 2-aminopyrimidines and their application in the synthesis of modern pharmaceuticals are considered.

  13. Correlation between chemical structure and rodent repellency of benzoic acid derivatives

    USGS Publications Warehouse

    Fearn, J.E.; DeWitt, J.B.

    1965-01-01

    Sixty-five benzoic acid derivatives were either prepared or obtained from commercial concerns, tested for rat repellency, and their indices of repellency computed. The data from these tests were considered analytically for any correlation between chemical structure and rat repellency. The results suggest a qualitative relationship which is useful in deciding probability of repellency in other compounds.

  14. Production of Fatty Acid-Derived Valuable Chemicals in Synthetic Microbes

    PubMed Central

    Yu, Ai-Qun; Pratomo Juwono, Nina Kurniasih; Leong, Susanna Su Jan; Chang, Matthew Wook

    2014-01-01

    Fatty acid derivatives, such as hydroxy fatty acids, fatty alcohols, fatty acid methyl/ethyl esters, and fatty alka(e)nes, have a wide range of industrial applications including plastics, lubricants, and fuels. Currently, these chemicals are obtained mainly through chemical synthesis, which is complex and costly, and their availability from natural biological sources is extremely limited. Metabolic engineering of microorganisms has provided a platform for effective production of these valuable biochemicals. Notably, synthetic biology-based metabolic engineering strategies have been extensively applied to refactor microorganisms for improved biochemical production. Here, we reviewed: (i) the current status of metabolic engineering of microbes that produce fatty acid-derived valuable chemicals, and (ii) the recent progress of synthetic biology approaches that assist metabolic engineering, such as mRNA secondary structure engineering, sensor-regulator system, regulatable expression system, ultrasensitive input/output control system, and computer science-based design of complex gene circuits. Furthermore, key challenges and strategies were discussed. Finally, we concluded that synthetic biology provides useful metabolic engineering strategies for economically viable production of fatty acid-derived valuable chemicals in engineered microbes. PMID:25566540

  15. Special aspects of the temperature dependence of EPR absorption of chemically carbonized polyvinylidene fluoride derivatives

    NASA Astrophysics Data System (ADS)

    Zhivulin, V. E.; Pesin, L. A.; Ivanov, D. V.

    2016-01-01

    The temperature dependences of electron paramagnetic resonance (EPR) absorption of two samples of chemically carbonized derivatives of polyvinylidene fluoride (PVDF) synthesized under different conditions have been measured in the range of 100-300 K. It has been found that the temperature dependence of the integrated intensity of the EPR signal of both samples is nonmonotonic and does not obey the classical Curie dependence characteristic of free radicals. An analytical expression that is consistent with experimental data and suggests the presence of an activation component of paramagnetism in the test samples has been obtained. The presence of a term independent of temperature in this equation also indicates the paramagnetic contribution of free electrons. The magnitude of the activation energy of the singlet-triplet transitions has been evaluated: δ = 0.067 eV. The HYSCORE spectra of chemically carbonized PVDF derivatives have been obtained for the first time.

  16. Chemical Aspects of Astrophysically Observed Extraterrestrial Methanol, Hydrocarbon Derivatives, and Ions.

    PubMed

    Olah, George A; Mathew, Thomas; Prakash, G K Surya; Rasul, Golam

    2016-02-10

    Astrophysically observed extraterrestrial molecular matter contains, besides hydrogen and water, methane and methanol as the most abundant species. Feasible pathways and chemical aspects of their formation as well as of derived hydrocarbon homologues and their ions (carbocations and carbanions) are discussed on the basis of observed similarities with our studied terrestrial chemistry. The preferred pathway for converting extraterrestrial methane according to Ali et al. is based on CH5(+) and Olah's related nonclassical carbonium ion chemistry. On the basis of the observed higher reactivity of methanol compared with methane in various chemical reactions, a feasible new pathway is proposed for the conversion of extraterrestrial methanol to hydrocarbons, their derivatives, and carbocations together with a possible connection with methonium ion-based chemistry. PMID:26760052

  17. A chemically amplified fullerene-derivative molecular electron-beam resist.

    PubMed

    Gibbons, Francis; Zaid, Hasnah M; Manickam, Mayandithevar; Preece, Jon A; Palmer, Richard E; Robinson, Alex P G

    2007-12-01

    Current lithographic resists depend on large polymeric materials, which are starting to limit further improvements in line-width roughness and feature size. Fullerene molecular resists use much smaller molecules to avoid this problem. However, such resists have poor radiation sensitivity. Chemical amplification of a fullerene derivative using an epoxy crosslinker and a photoacid generator is demonstrated. The sensitivity of the material is increased by two orders of magnitude, and 20-nm line widths are patterned. PMID:18008296

  18. Cardiac chemical constant. Part I: Derivation of the characteristic phenomenological equation.

    PubMed

    Phillips, C A

    1990-01-01

    A physiochemical parameter is derived and defined as the cardiac chemical equilibrium dissociation constant (KD). KD is based upon a phenomenological model in which the cardiac muscle chemical reaction kinetics describe the interconversion between long and short units (i.e. the individual sarcomere is fully extended or fully contracted). KD is defined as the ratio of the number of units in the long state to the number of units in the short state. The mathematical development proceeds through four stages: derivation of the governing differential equation during cardiac systole; simplification of the differential equation to describe the cardiac model; determination of the upper and lower limits and average value of Nt (the total number of units in a hypothetical mid-wall circumferential fibre): definition and calculation of the cardiac chemical constant (KD). KD is shown to describe a series of equilibrium points throughout cardiac systole. This requires that each mechanical equilibrium state (a series of static, steady-state intervals over time) is also associated with its own specific chemical equilibrium state. PMID:2296165

  19. An overview on chemical derivatization and stability aspects of selected avermectin derivatives.

    PubMed

    Awasthi, Atul; Razzak, Majid; Al-Kassas, Raida; Harvey, Joanne; Garg, Sanjay

    2012-01-01

    Naturally occurring avermectins (AVMs) and its derivatives are potent endectocide compounds, well-known for their novel mode of action against a broad range of nematode and anthropod animal parasites. In this review, chemical and pharmaceutical aspects of AVM derivatives are described including stability, synthetic and purification processes, impurities and degradation pathways, and subsequent suggestions are made to improve the chemical stability. It has been found out that unique structure of AVM molecules and presence of labile groups facilitated the derivatization of AVM into various compounds showing strong anthelmintic activity. However, the same unique structure is also responsible for labile nature related to sensitive stability profile of molecules. AVMs are found to be unstable in acidic and alkaline conditions. In addition, these compounds are sensitive to strong light, and subsequently presence of photo-isomer in animals treated topically with AVM product is well known. The pharmacoepial recommendations for addition of antioxidant into drug substance, as well as its products, arises from the fact that AVM are very sensitive to oxidation. Formations of solvates, salts, epoxides, reduction of double bonds and developing liquid formulation around pH 6.2, were some chemical approaches used to retard the degradation in AVM. This coherent review will contribute towards the better understanding of the correlation of chemical processes, stability profile and biological activity; therefore, it will help to design the shelf-life stable formulations containing AVMs. PMID:22863694

  20. Inhibition of anthrax lethal factor by curcumin and chemically modified curcumin derivatives

    PubMed Central

    Zhang, Yu; Golub, Lorne M.; Johnson, Francis; Simon, Sanford R.

    2014-01-01

    Curcuma longa Curcumin (diferuloylmethane), the active ingredient in the eastern spice turmeric (Curcuma longa), has been shown to inhibit the activities of numerous enzymes and signaling molecules involved in cancer, bacterial and viral infections and inflammatory diseases. We have investigated the inhibitory activities of curcumin and chemically modified curcumin (CMC) derivatives toward lethal factor (LF), the proteolytic component of anthrax toxin produced by the bacterium Bacillus anthracis. Curcumin (Compound 1) appears to inhibit the catalytic activity of LF through a mixture of inhibitory mechanisms, without significant compromise to the binding of oligopeptide substrates, and one CMC derivative in particular, Compound 3 (4-phenylaminocarbonylbis-demethoxycurcumin), is capable of inhibiting LF with potency comparable with the parent compound, while also showing improved solubility and stability. The quantitative reduction in catalytic activity achieved by the different CMC derivatives appears to be a function of the proportion of the multiple mechanisms through which they inhibit the enzyme. PMID:24102525

  1. Use of chemical genomics in assessment of the UPR.

    PubMed

    Saito, Sakae; Tomida, Akihiro

    2011-01-01

    Glucose deprivation, one of the major physiological conditions in solid tumor, leads to activation of the unfolded protein response (UPR) in cancer cells. The UPR occurs through the transcriptional and translational regulatory mechanisms that improve the capacity of the endoplasmic reticulum (ER) to fold and traffic proteins and allows the cell to survive under stress conditions. We previously reported that the macrocyclic compound versipelostatin and the antidiabetic biguanides metformin, buformin, and phenformin could inhibit the UPR during glucose deprivation as well as induce the UPR by treatment of cells with 2-deoxy-d-glucose (2DG), a glycolysis inhibitor. Versipelostatin and biguanides show highly selective cytotoxicity to glucose-deprived tumor cells and exert in vivo antitumor activity; thus, these compounds would be interesting anticancer agent candidates. By microarray analysis, we demonstrated that cancer cells under glucose deprivation conditions caused activation of the UPR transcription program, which was suppressed broadly by versipelostatin and biguanides. We also identified the drug-driven gene signatures that can be used to discover pharmacologic UPR modulators. Indeed, we found several bioactive drugs, such as pyrvinium pamoate, valinomycin, and rottlerin, that selectively suppressed 2DG-induced GRP78 promoter activity as versipelostatin and biguanide did. Together with growing bioinformatics databases and analytical tools, our approach could provide a chemical genomic basis for developing UPR-targeting drugs against solid tumors. PMID:21329808

  2. Evaluation of Chemical Warfare Agent Percutaneous Vapor Toxicity: Derivation of Toxicity Guidelines for Assessing Chemical Protective Ensembles.

    SciTech Connect

    Watson, A.P.

    2003-07-24

    Percutaneous vapor toxicity guidelines are provided for assessment and selection of chemical protective ensembles (CPEs) to be used by civilian and military first responders operating in a chemical warfare agent vapor environment. The agents evaluated include the G-series and VX nerve agents, the vesicant sulfur mustard (agent HD) and, to a lesser extent, the vesicant Lewisite (agent L). The focus of this evaluation is percutaneous vapor permeation of CPEs and the resulting skin absorption, as inhalation and ocular exposures are assumed to be largely eliminated through use of SCBA and full-face protective masks. Selection of appropriately protective CPE designs and materials incorporates a variety of test parameters to ensure operability, practicality, and adequacy. One aspect of adequacy assessment should be based on systems tests, which focus on effective protection of the most vulnerable body regions (e.g., the groin area), as identified in this analysis. The toxicity range of agent-specific cumulative exposures (Cts) derived in this analysis can be used as decision guidelines for CPE acceptance, in conjunction with weighting consideration towards more susceptible body regions. This toxicity range is bounded by the percutaneous vapor estimated minimal effect (EME{sub pv}) Ct (as the lower end) and the 1% population threshold effect (ECt{sub 01}) estimate. Assumptions of exposure duration used in CPE certification should consider that each agent-specific percutaneous vapor cumulative exposure Ct for a given endpoint is a constant for exposure durations between 30 min and 2 hours.

  3. Tyrosine-Specific Chemical Modification with in Situ Hemin-Activated Luminol Derivatives.

    PubMed

    Sato, Shinichi; Nakamura, Kosuke; Nakamura, Hiroyuki

    2015-11-20

    Tyrosine-specific chemical modification was achieved using in situ hemin-activated luminol derivatives. Tyrosine residues in peptide and protein were modified effectively with N-methylated luminol derivatives under oxidative conditions in the presence of hemin and H2O2. Both single and double modifications of the tyrosine residue occurred in the reaction of angiotensin II with N-methylated luminol derivative 9. Tyrosine-specific chemical modification of the model protein bovine serum albumin (BSA) revealed that the surface-exposed tyrosine residues were selectively modified with 9. We succeeded in the functionalization of several proteins using azide-conjugated compound 18 using alkyne-conjugated probes by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) or dibenzocyclooctyne (DBCO)-mediated copper-free click chemistry. This tyrosine-specific modification was orthogonal to conventional lysine modification by N-hydroxysuccinimide (NHS) ester, and dual functionalization by fluorescence modification of tyrosine residues and PEG modification of lysine residues was achieved without affecting the modification efficiency. PMID:26356088

  4. Feasibility study of the natural derived chitosan dialdehyde for chemical modification of collagen.

    PubMed

    Liu, Xinhua; Dan, Nianhua; Dan, Weihua; Gong, Juxia

    2016-01-01

    The aim of this study is to evaluate the chemical crosslinking effects of the natural derived chitosan dialdehyde (OCS) on collagen. Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and circular dichroism (CD) measurements suggest that introducing OCS might not destroy the natural triple helix conformation of collagen but enhance the thermal-stability of collagen. Meanwhile, a denser fibrous network of cross-linked collagen is observed by atomic force microscopy. Further, scanning electron microscopy (SEM) and aggregation kinetics analysis confirm that the fibrillation process of collagen advances successfully and OCS could lengthen the completion time of collagen fibrillogenesis but raise the reconstitution rate of collagen fibrils or microfibrils. Besides, the cytocompatibility analysis implies that when the dosage of OCS is less than 15%, introducing OCS into collagen might be favorable for the cell's adhesion, growth and proliferation. Taken as a whole, the present study demonstrates that OCS might be an ideal crosslinker for the chemical fixation of collagen. PMID:26562557

  5. Literature-derived absorption coefficients for 39 chemicals via oral and inhalation routes of exposure.

    PubMed

    Owen, B A

    1990-06-01

    Absorption refers to the amount of a chemical or substance that is able to cross biological membranes and be taken up by the blood for subsequent distribution to target tissues. The term absorption coefficient, as used here, is a numerical descriptor characterizing that fractional uptake by the blood and represents an approximation of the biological "dose" ultimately responsible for toxicity or other effects following exposure or chemical administration. Regulatory agencies utilize absorption coefficients in deriving acceptable daily intake values and health advisory indices, as well as in quantifying radiological risk. However, absorption coefficients do not exist for many chemicals due to a paucity of appropriate toxicological data. As a result, regulatory policy must often provide default options that assume, for example, 100% absorption by all routes to permit evaluation of "data-gap" chemicals. This paper attempts to improve the situation by providing a discrete source of route-specific absorption coefficients that are based on experimental data reported in the open literature. The estimates presented here are the result of an extensive investigation of three data bases (TOXLINE, HSDB, and CIS), many agency documents, and nearly 200 articles from 30 scientific journals. Acknowledging that absorption efficiency varies with dietary status, age, and several other situation-specific factors, the estimates presented here are intended to reflect absorption by the average adult human. PMID:2196635

  6. Hydrodeoxygenation processes: advances on catalytic transformations of biomass-derived platform chemicals into hydrocarbon fuels.

    PubMed

    De, Sudipta; Saha, Basudeb; Luque, Rafael

    2015-02-01

    Lignocellulosic biomass provides an attractive source of renewable carbon that can be sustainably converted into chemicals and fuels. Hydrodeoxygenation (HDO) processes have recently received considerable attention to upgrade biomass-derived feedstocks into liquid transportation fuels. The selection and design of HDO catalysts plays an important role to determine the success of the process. This review has been aimed to emphasize recent developments on HDO catalysts in effective transformations of biomass-derived platform molecules into hydrocarbon fuels with reduced oxygen content and improved H/C ratios. Liquid hydrocarbon fuels can be obtained by combining oxygen removal processes (e.g. dehydration, hydrogenation, hydrogenolysis, decarbonylation etc.) as well as by increasing the molecular weight via C-C coupling reactions (e.g. aldol condensation, ketonization, oligomerization, hydroxyalkylation etc.). Fundamentals and mechanistic aspects of the use of HDO catalysts in deoxygenation reactions will also be discussed. PMID:25443804

  7. Expedited access to vinaxanthone and chemically edited derivatives possessing neuronal regenerative effects through ynone coupling reactions.

    PubMed

    Chin, Matthew R; Zlotkowski, Katherine; Han, Michelle; Patel, Saagar; Eliasen, Anders M; Axelrod, Abram; Siegel, Dionicio

    2015-04-15

    The natural product vinaxanthone has demonstrated a remarkable capability to promote nerve growth following injury or transplantation. In rats following total transection of the spinal cord delivery of vinaxanthone enhanced axonal regeneration, remyelination and angiogenesis at the site of injury all leading to an improved reinstatement of motor function. Through the development of a new ynone coupling reaction, chemically edited derivatives of vinaxanthone have been prepared and studied for improved activity. The coupling reaction allows rapid access to new derivatives, wherein n ynone precursors provide n(2) vinaxanthone analogues. These compounds have been tested for their ability to promote neuronal regrowth using laser axotomy, severing axonal connections in Caenorhabditis elegans. This precise microsurgery using C. elegans allows a new in vivo approach for medicinal chemistry based optimization of neuronal growth promoting compounds. PMID:25615693

  8. Hierarchy of Electronic Properties of Chemically Derived and Pristine Graphene Probed by Microwave Imaging

    SciTech Connect

    Kundhikanjana, W.

    2010-06-02

    Local electrical imaging using microwave impedance microscope is performed on graphene in different modalities, yielding a rich hierarchy of the local conductivity. The low-conductivity graphite oxide and its derivatives show significant electronic inhomogeneity. For the conductive chemical graphene, the residual defects lead to a systematic reduction of the microwave signals. In contrast, the signals on pristine graphene agree well with a lumped-element circuit model. The local impedance information can also be used to verify the electrical contact between overlapped graphene pieces.

  9. Accumulation of plastic-derived chemicals in tissues of seabirds ingesting marine plastics.

    PubMed

    Tanaka, Kosuke; Takada, Hideshige; Yamashita, Rei; Mizukawa, Kaoruko; Fukuwaka, Masa-aki; Watanuki, Yutaka

    2013-04-15

    We analyzed polybrominated diphenyl ethers (PBDEs) in abdominal adipose of oceanic seabirds (short-tailed shearwaters, Puffinus tenuirostris) collected in northern North Pacific Ocean. In 3 of 12 birds, we detected higher-brominated congeners (viz., BDE209 and BDE183), which are not present in the natural prey (pelagic fish) of the birds. The same compounds were present in plastic found in the stomachs of the 3 birds. These data suggested the transfer of plastic-derived chemicals from ingested plastics to the tissues of marine-based organisms. PMID:23298431

  10. Derivation of the chemical-equilibrium rate coefficient using scattering theory

    NASA Technical Reports Server (NTRS)

    Mickens, R. E.

    1977-01-01

    Scattering theory is applied to derive the equilibrium rate coefficient for a general homogeneous chemical reaction involving ideal gases. The reaction rate is expressed in terms of the product of a number of normalized momentum distribution functions, the product of the number of molecules with a given internal energy state, and the spin-averaged T-matrix elements. An expression for momentum distribution at equilibrium for an arbitrary molecule is presented, and the number of molecules with a given internal-energy state is represented by an expression which includes the partition function.

  11. Chemical constituents of marine mangrove-derived endophytic fungus Alternaria tenuissima EN-192

    NASA Astrophysics Data System (ADS)

    Sun, Hong; Gao, Shushan; Li, Xiaoming; Li, Chunshun; Wang, Bingui

    2013-03-01

    A chemical investigation of the ethyl acetate extract of the fermentation broth of Alternaria tenuissima EN-192, an endophytic fungus obtained from the stems of the marine mangrove plant Rhizophora stylosa, resulted in the isolation of nine known secondary metabolites, including four indole-diterpenoids: penijanthine A ( 1), paspaline ( 2), paspalinine ( 3), and penitrem A ( 4); three tricycloalternarene derivatives: tricycloalternarene 3a ( 5), tricycloalternarene 1b ( 6), and tricycloalternarene 2b ( 7); and two alternariol congeners: djalonensone ( 8) and alternariol ( 9). The chemical structures of these metabolites were characterized through a combination of detailed spectroscopic analyses and their comparison with reports from the literature. The inhibitory activities of each isolated compound against four bacteria were evaluated and compounds 5 and 8 displayed moderate activity against the aquaculture pathogenic bacterium Vibrio anguillarum, with inhibition zone diameters of 8 and 9 mm, respectively, at 100 μg/disk. To the best of our knowledge, this is the first report on the secondary metabolites of mangrove-derived A lternaria tenuissima and also the first report of the isolation of indole-diterpenoids from fungal genus A lternaria.

  12. Combined physical-chemical and aerobic biological treatments of wastewater derived from sauce manufacturing.

    PubMed

    Martn, M A; Gonzlez, I; Siles, J A; Berrios, M; Martn, A

    2013-04-01

    The viability of an integrated coagulation-flocculation and aerobic treatment for purifying wastewater derived from a sauce manufacturing industry was evaluated. The best coagulation-flocculation results were obtained at alkaline pH, showing the greatest turbidity removal efficiency (greater than 90%) and a total chemical oxygen demand (COD) removal of approximately 80%, Additionally, experiments at alkaline pH reduce the reagent requirements (coagulant concentration of 0.4 mL/L and flocculant concentration of 4.0 mL/L) providing a consequent economic benefit as compared to experiments at neutral and acidic pH. Another set of experiments was conducted in a sequencing batch reactor to evaluate the aerobic biodegradability of the remnant dissolved organic matter. The effluent from the physical-chemical pre-treatment at alkaline pH again showed the highest biodegradability (76%), with a global COD total removal of 98%. The results showed that the combination of both techniques could be a viable alternative to efficiently treat wastewater derived from sauce manufacturing. PMID:23697239

  13. Determination of the chemical structures of tandyukisins B-D, isolated from a marine sponge-derived fungus.

    PubMed

    Yamada, Takeshi; Umebayashi, Yoshihide; Kawashima, Maiko; Sugiura, Yuma; Kikuchi, Takashi; Tanaka, Reiko

    2015-05-01

    Tandyukisins B-D (1-3), novel decalin derivatives, have been isolated from a strain of Trichoderma harzianum OUPS-111D-4 originally derived from the marine sponge Halichondria okadai, and their structures have been elucidated on the basis of spectroscopic analyses using 1D and 2D NMR techniques. In addition, their chemical structures were established by chemical transformation. They exhibited weak cytotoxicity, but selective growth inhibition on panel screening using 39 human cancer cell lines. PMID:26006715

  14. Determination of the Chemical Structures of Tandyukisins B–D, Isolated from a Marine Sponge-Derived Fungus

    PubMed Central

    Yamada, Takeshi; Umebayashi, Yoshihide; Kawashima, Maiko; Sugiura, Yuma; Kikuchi, Takashi; Tanaka, Reiko

    2015-01-01

    Tandyukisins B–D (1–3), novel decalin derivatives, have been isolated from a strain of Trichoderma harzianum OUPS-111D-4 originally derived from the marine sponge Halichondria okadai, and their structures have been elucidated on the basis of spectroscopic analyses using 1D and 2D NMR techniques. In addition, their chemical structures were established by chemical transformation. They exhibited weak cytotoxicity, but selective growth inhibition on panel screening using 39 human cancer cell lines. PMID:26006715

  15. Biguanide-induced mitochondrial dysfunction yields increased lactate production and cytotoxicity of aerobically-poised HepG2 cells and human hepatocytes in vitro

    SciTech Connect

    Dykens, James A. Jamieson, Joseph; Marroquin, Lisa; Nadanaciva, Sashi; Billis, Puja A.; Will, Yvonne

    2008-12-01

    As a class, the biguanides induce lactic acidosis, a hallmark of mitochondrial impairment. To assess potential mitochondrial impairment, we evaluated the effects of metformin, buformin and phenformin on: 1) viability of HepG2 cells grown in galactose, 2) respiration by isolated mitochondria, 3) metabolic poise of HepG2 and primary human hepatocytes, 4) activities of immunocaptured respiratory complexes, and 5) mitochondrial membrane potential and redox status in primary human hepatocytes. Phenformin was the most cytotoxic of the three with buformin showing moderate toxicity, and metformin toxicity only at mM concentrations. Importantly, HepG2 cells grown in galactose are markedly more susceptible to biguanide toxicity compared to cells grown in glucose, indicating mitochondrial toxicity as a primary mode of action. The same rank order of potency was observed for isolated mitochondrial respiration where preincubation (40 min) exacerbated respiratory impairment, and was required to reveal inhibition by metformin, suggesting intramitochondrial bio-accumulation. Metabolic profiling of intact cells corroborated respiratory inhibition, but also revealed compensatory increases in lactate production from accelerated glycolysis. High (mM) concentrations of the drugs were needed to inhibit immunocaptured respiratory complexes, supporting the contention that bioaccumulation is involved. The same rank order was found when monitoring mitochondrial membrane potential, ROS production, and glutathione levels in primary human hepatocytes. In toto, these data indicate that biguanide-induced lactic acidosis can be attributed to acceleration of glycolysis in response to mitochondrial impairment. Indeed, the desired clinical outcome, viz., decreased blood glucose, could be due to increased glucose uptake and glycolytic flux in response to drug-induced mitochondrial dysfunction.

  16. Metabolic engineering of Saccharomyces cerevisiae for production of fatty acid-derived biofuels and chemicals.

    PubMed

    Runguphan, Weerawat; Keasling, Jay D

    2014-01-01

    As the serious effects of global climate change become apparent and access to fossil fuels becomes more limited, metabolic engineers and synthetic biologists are looking towards greener sources for transportation fuels. In recent years, microbial production of high-energy fuels by economically efficient bioprocesses has emerged as an attractive alternative to the traditional production of transportation fuels. Here, we engineered the budding yeast Saccharomyces cerevisiae to produce fatty acid-derived biofuels and chemicals from simple sugars. Specifically, we overexpressed all three fatty acid biosynthesis genes, namely acetyl-CoA carboxylase (ACC1), fatty acid synthase 1 (FAS1) and fatty acid synthase 2 (FAS2), in S. cerevisiae. When coupled to triacylglycerol (TAG) production, the engineered strain accumulated lipid to more than 17% of its dry cell weight, a four-fold improvement over the control strain. Understanding that TAG cannot be used directly as fuels, we also engineered S. cerevisiae to produce drop-in fuels and chemicals. Altering the terminal "converting enzyme" in the engineered strain led to the production of free fatty acids at a titer of approximately 400 mg/L, fatty alcohols at approximately 100mg/L and fatty acid ethyl esters (biodiesel) at approximately 5 mg/L directly from simple sugars. We envision that our approach will provide a scalable, controllable and economic route to this important class of chemicals. PMID:23899824

  17. Ag electrode modified with polyhexamethylene biguanide stabilized silver nanoparticles: a new type of SERS substrates for detection of enzymatically generated thiocholine

    NASA Astrophysics Data System (ADS)

    Tepanov, A. A.; Nechaeva, N. L.; Prokopkina, T. A.; Kudrinskiy, A. A.; Kurochkin, I. N.; Lisichkin, G. V.

    2015-11-01

    The detection of thiocholine is one of the most widespread techniques for estimation of the cholinesterase activity – acetylcholinesterase and butyrylcholinesterase. Both cholinesterases can be inhibited by organophosphates and carbamates and accordingly can be considered for estimation of these pollutants in the environment. In the current work, SERS spectroscopy was applied for the thiocholine detection. The Ag electrodes modified with silver nanoparticles stabilized by polyhexamethylene biguanide were for the first time suggested as SERS-substrates for that purpose. Such electrodes can be applicable for SERS detection of submicromolar concentrations of thiocholine.

  18. Biomass-derived Syngas Utilization for Fuels and Chemicals - Final Report

    SciTech Connect

    David C. Dayton

    2010-03-24

    Executive Summary The growing gap between petroleum production and demand, mounting environmental concerns, and increasing fuel prices have stimulated intense interest in research and development (R&D) of alternative fuels, both synthetic and bio-derived. Currently, the most technically defined thermochemical route for producing alternative fuels from lignocellulosic biomass involves gasification/reforming of biomass to produce syngas (carbon monoxide [CO] + hydrogen [H2]), followed by syngas cleaning, Fischer-Tropsch synthesis (FTS) or mixed alcohol synthesis, and some product upgrading via hydroprocessing or separation. A detailed techno-economic analysis of this type of process has recently been published [1] and it highlights the need for technical breakthroughs and technology demonstration for gas cleanup and fuel synthesis. The latter two technical barrier areas contribute 40% of the total thermochemical ethanol cost and 70% of the production cost, if feedstock costs are factored out. Developing and validating technologies that reduce the capital and operating costs of these unit operations will greatly reduce the risk for commercializing integrated biomass gasification/fuel synthesis processes for biofuel production. The objective of this project is to develop and demonstrate new catalysts and catalytic processes that can efficiently convert biomass-derived syngas into diesel fuel and C2-C4 alcohols. The goal is to improve the economics of the processes by improving the catalytic activity and product selectivity, which could lead to commercialization. The project was divided into 4 tasks: Task 1: Reactor Systems: Construction of three reactor systems was a project milestone. Construction of a fixed-bed microreactor (FBR), a continuous stirred tank reactor (CSTR), and a slurry bubble column reactor (SBCR) were completed to meet this milestone. Task 2: Iron Fischer-Tropsch (FT) Catalyst: An attrition resistant iron FT catalyst will be developed and tested. Task 3: Chemical Synthesis: Promising process routes will be identified for synthesis of selected chemicals from biomass-derived syngas. A project milestone was to select promising mixed alcohol catalysts and screen productivity and performance in a fixed bed micro-reactor using bottled syngas. This milestone was successfully completed in collaboration withour catalyst development partner. Task 4: Modeling, Engineering Evaluation, and Commercial Assessment: Mass and energy balances of conceptual commercial embodiment for FT and chemical synthesis were completed.

  19. Chemical Signals of Synthetic Disaccharide Derivatives Dominate Rhamnolipids at Controlling Multiple Bacterial Activities.

    PubMed

    Singh, Nischal; Shetye, Gauri S; Zheng, Hewen; Sun, Jiayue; Luk, Yan-Yeung

    2016-01-01

    Microbes secrete molecules that modify their environment. Here, we demonstrate a class of synthetic disaccharide derivatives (DSDs) that mimics and dominates the activity of naturally secreted rhamnolipids by Pseudomonas aeruginosa. The DSDs exhibit the dual function of activating and inhibiting the swarming motility through a concentration-dependent activity reversal that is characteristic of signaling molecules. Whereas DSDs tethered with a saturated farnesyl group exhibit inhibition of both biofilm formation and swarming motility, with higher activities than rhamnolipids, a saturated farnesyl tethered with a sulfonate group only inhibits swarming motility but promote biofilm formation. These results identified important structural elements for controlling swarming motility, biofilm formation, and bacterial adhesion and suggest an effective chemical approach to control intertwined signaling processes that are important for biofilm formation and motilities. PMID:26511780

  20. Fatty Acid-Derived Biofuels and Chemicals Production in Saccharomyces cerevisiae

    PubMed Central

    Zhou, Yongjin J.; Buijs, Nicolaas A.; Siewers, Verena; Nielsen, Jens

    2014-01-01

    Volatile energy costs and environmental concerns have spurred interest in the development of alternative, renewable, sustainable, and cost-effective energy resources. Environment-friendly processes involving microbes can be used to synthesize advanced biofuels. These fuels have the potential to replace fossil fuels in supporting high-power demanding machinery such as aircrafts and trucks. From an engineering perspective, the pathway for fatty acid biosynthesis is an attractive route for the production of advanced fuels such as fatty acid ethyl esters, fatty alcohols, and alkanes. The robustness and excellent accessibility to molecular genetics make the yeast Saccharomyces cerevisiae a suitable host for the purpose of bio-manufacturing. Recent advances in metabolic engineering, as well as systems and synthetic biology, have now provided the opportunity to engineer yeast metabolism for the production of fatty acid-derived fuels and chemicals. PMID:25225637

  1. Fatty Acid-Derived Biofuels and Chemicals Production in Saccharomyces cerevisiae.

    PubMed

    Zhou, Yongjin J; Buijs, Nicolaas A; Siewers, Verena; Nielsen, Jens

    2014-01-01

    Volatile energy costs and environmental concerns have spurred interest in the development of alternative, renewable, sustainable, and cost-effective energy resources. Environment-friendly processes involving microbes can be used to synthesize advanced biofuels. These fuels have the potential to replace fossil fuels in supporting high-power demanding machinery such as aircrafts and trucks. From an engineering perspective, the pathway for fatty acid biosynthesis is an attractive route for the production of advanced fuels such as fatty acid ethyl esters, fatty alcohols, and alkanes. The robustness and excellent accessibility to molecular genetics make the yeast Saccharomyces cerevisiae a suitable host for the purpose of bio-manufacturing. Recent advances in metabolic engineering, as well as systems and synthetic biology, have now provided the opportunity to engineer yeast metabolism for the production of fatty acid-derived fuels and chemicals. PMID:25225637

  2. Analytical characterization of plasma membrane-derived vesicles produced via osmotic and chemical vesiculation.

    PubMed

    Sarabipour, Sarvenaz; Chan, Robin B; Zhou, Bowen; Di Paolo, Gilbert; Hristova, Kalina

    2015-07-01

    Plasma membrane-derived vesicles are being used in biophysical and biochemical research as a simple, yet native-like model of the cellular membrane. Here we report on the characterization of vesicles produced via two different vesiculation methods from CHO and A431 cell lines. The first method is a recently developed method which utilizes chloride salts to induce osmotic vesiculation. The second is a well established chemical vesiculation method which uses DTT and formaldehyde. We show that both vesiculation methods produce vesicles which contain the lipid species previously reported in the plasma membrane of these cell lines. The two methods lead to small but statistically significant differences in two lipid species only; phosphatidylcholine (PC) and plasmalogen phosphatidylethanolamine (PEp). However, highly significant differences were observed in the degree of incorporation of a membrane receptor and in the degree of retention of soluble cytosolic proteins within the vesicles. PMID:25896659

  3. Physico-chemical characterization and biological response of Labeo rohita-derived hydroxyapatite scaffold.

    PubMed

    Mondal, S; Mondal, A; Mandal, N; Mondal, B; Mukhopadhyay, S S; Dey, A; Singh, S

    2014-07-01

    The chemically treated Labeo rohita scale is used for synthesizing hydroxyapatite (HAp) biomaterials. Thermogravimetric and differential thermal analyses of fish scale materials reveal the different phase changes with temperature and find out the suitable calcination temperatures. The composition and structures of wet ball-milled calcined HAp powders are characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis (EDX). The EDX as well as chemical analysis of fish scale-derived apatite materials confirms that the Ca/P ratio is 1.71. The compressive stress, hardness and porosity have been evaluated on sintered HAp biomaterials. The cell attachment on HAp surfaces, cytotoxicity evaluation and MTT assay, which are carried out in RAW macrophage-like cell line media demonstrate good biocompatibility. The histological analysis also supports the bioaffinity of processed HAp biomaterials in Wistar rat model for investigating the contact reaction and stability at the artificial or natural prosthesis interface. PMID:24288117

  4. Physical, morphological, and chemical studies of dusts derived from the machining of composite-epoxy materials.

    PubMed

    Boatman, E S; Covert, D; Kalman, D; Luchtel, D; Omenn, G S

    1988-04-01

    This work (in three parts) inquires into whether respirable dusts derived from the machining of six composite-epoxy materials (e.g., aircraft industry) may pose a health risk to the operators. Dust samples representative of a variety of composites and structural components were aerodynamically sized and fractionated. Bulk and fractionated samples were examined by light and electron microscopy and analyzed chemically by thermogravimetry (TGA), gas chromatography (GC) and mass spectrometry (MS). Relative fractions of respirable to total mass of bulk samples were less than 3%; aerodynamic diameters of fractionated particles ranged from 0.8 to 2.0 microns. By microscopy, bulk particles ranged from 7 to 11 microns in diameter, with mean aspect ratios from 4 to 8:1. Mean diameter of fractionated particles was 2.7 microns. By TGA, weight losses were negligible below 250 degrees C and variable but elevated at temperatures up to 860 degrees C. In assays of vapors released at 250 degrees C, GC/MS indicated a variety of compounds in different amounts for each sample. We conclude that under the present machining protocols, dusts at the tool face contained few particles of respirable size with no evidence of splitting of fibers longitudinally and were of a low volatilizable chemical content. Overall, composites were judged to be well cured and thermally stable. PMID:3349976

  5. Biodistribution profiling of the chemical modified hyaluronic acid derivatives used for oral delivery system.

    PubMed

    Hsieh, Chien-Ming; Huang, Yu-Wen; Sheu, Ming-Thau; Ho, Hsiu-O

    2014-03-01

    A series of adipic acid dihydrazide (ADH)-modified hyaluronic acid (HA-ADH) compounds were synthesized and conjugated with QDots (QDots-HA conjugates) to assess the effects of the molecular weight (MW) and extent of chemical modification of HA on its biodistribution. Their physicochemical structures were confirmed by complementary application of GPC, (1)H NMR, FTIR, and UV-vis spectroscopic methods. In vivo imaging of QDots-HA conjugates after oral administration was analyzed to investigate their biodistribution in nude mice. Simultaneously, real-time bioimaging was confirmed by an anatomical analysis to investigate the organ-specific accumulation of conjugates. QDot-HA conjugates with a higher MW of HA or high modification presented relatively slow clearance leading to an extension of the retention time for up to 10 days, whereas those with lower MWs of HA or a low modification extent exhibited quick absorption and elimination after oral administration. Taken together, HA derivatives with suitable MWs and chemical modification extents can be used to design new, more-sophisticated, and intelligent HA-based vehicles for oral delivery with diverse characteristics. PMID:24315950

  6. Investigation of reports of sexual dysfunction among male chemical workers manufacturing stilbene derivatives.

    PubMed

    Quinn, M M; Wegman, D H; Greaves, I A; Hammond, S K; Ellenbecker, M J; Spark, R F; Smith, E R

    1990-01-01

    A Health Hazard Evaluation was conducted by the National Institute for Occupational Safety and Health in an area of a large chemical plant that manufactured the stilbene derivative 4,4'-diaminostilbene-2,2'-disulfonic acid, an intermediate used for the production of optical brightening agents. Men employed in the area reported problems with impotence. The study population consisted of 44 men aged 20-57 years (mean age 37) employed in the area at the time of the evaluation. An industrial hygiene investigation, health and work history questionnaire survey, physical examinations, and blood chemistry and serum hormone evaluation were conducted. Fourteen percent of the men reported symptoms of impotence over the preceding 6 or more months, 7% had potency problems of shorter duration, and 7% were not currently impotent but had experienced impotence for 6 or more months in the past; 36% experienced decreased libido, all since beginning work in the production area. Low levels of serum testosterone (less than 350 ng/dl) were observed in 37% of the men. The low serum testosterone concentrations were not accounted for fully by diurnal variation or an effect of rotating shift work. It is suggested that exposures to chemicals possessing estrogenic activity may be related to the observed health effects in these workers. PMID:2378370

  7. Degree of polymerization of 5,6-dihydroxyindole-derived eumelanin from chemical degradation study.

    PubMed

    Okuda, Hidekazu; Yoshino, Kyoji; Wakamatsu, Kazumasa; Ito, Shosuke; Sota, Takayuki

    2014-07-01

    Eumelanin is a brown-black pigment comprising 5,6-dihydroxyindole (DHI) and its 2-carboxy derivative (DHICA), but the detailed structure of eumelanin is unclear. Chemical degradation is a powerful tool for analyzing melanin. H2 O2 oxidation degradation of eumelanin affords pyrrole-2,3,5-tricarboxylic acid (PTCA) and pyrrole-2,3-dicarboxylic acid (PDCA). The ratio of PDCA to PTCA provides information about the eumelanin structure. In this article, we propose simple equations on the basis of previous experimental results on dimer yields for evaluating the yields of PTCA and PDCA from any DHI oligomers. Assuming the chemical disorder model of DHI-melanin, we solve an equation where a theoretical expression for the ratio of PDCA to PTCA is set to the corresponding experimental value to obtain a plausible Poisson distribution of DHI oligomers. The results demonstrate that the main contributors to DHI-melanin are tetramers and pentamers as shown by the mass spectrometry. PMID:24750564

  8. Investigation of reports of sexual dysfunction among male chemical workers manufacturing stilbene derivatives

    SciTech Connect

    Quinn, M.M.; Wegman, D.H.; Greaves, I.A.; Hammond, S.K.; Ellenbecker, M.J.; Spark, R.F.; Smith, E.R. )

    1990-01-01

    A Health Hazard Evaluation was conducted by the National Institute for Occupational Safety and Health in an area of a large chemical plant that manufactured the stilbene derivative 4,4'-diaminostilbene-2,2'-disulfonic acid, an intermediate used for the production of optical brightening agents. Men employed in the area reported problems with impotence. The study population consisted of 44 men aged 20-57 years (mean age 37) employed in the area at the time of the evaluation. An industrial hygiene investigation, health and work history questionnaire survey, physical examinations, and blood chemistry and serum hormone evaluation were conducted. Fourteen percent of the men reported symptoms of impotence over the preceding 6 or more months, 7% had potency problems of shorter duration, and 7% were not currently impotent but had experienced impotence for 6 or more months in the past; 36% experienced decreased libido, all since beginning work in the production area. Low levels of serum testosterone (less than 350 ng/dl) were observed in 37% of the men. The low serum testosterone concentrations were not accounted for fully by diurnal variation or an effect of rotating shift work. It is suggested that exposures to chemicals possessing estrogenic activity may be related to the observed health effects in these workers.

  9. Plasmid-derived DNA Strand Displacement Gates for Implementing Chemical Reaction Networks

    PubMed Central

    Chen, Yuan-Jyue; Rao, Sundipta D.; Seelig, Georg

    2015-01-01

    DNA nanotechnology requires large amounts of highly pure DNA as an engineering material. Plasmid DNA could meet this need since it is replicated with high fidelity, is readily amplified through bacterial culture and can be stored indefinitely in the form of bacterial glycerol stocks. However, the double-stranded nature of plasmid DNA has so far hindered its efficient use for construction of DNA nanostructures or devices that typically contain single-stranded or branched domains. In recent work, it was found that nicked double stranded DNA (ndsDNA) strand displacement gates could be sourced from plasmid DNA. The following is a protocol that details how these ndsDNA gates can be efficiently encoded in plasmids and can be derived from the plasmids through a small number of enzymatic processing steps. Also given is a protocol for testing ndsDNA gates using fluorescence kinetics measurements. NdsDNA gates can be used to implement arbitrary chemical reaction networks (CRNs) and thus provide a pathway towards the use of the CRN formalism as a prescriptive molecular programming language. To demonstrate this technology, a multi-step reaction cascade with catalytic kinetics is constructed. Further it is shown that plasmid-derived components perform better than identical components assembled from synthetic DNA. PMID:26649734

  10. Optimizing Performance Parameters of Chemically-Derived Graphene/p-Si Heterojunction Solar Cell.

    PubMed

    Batra, Kamal; Nayak, Sasmita; Behura, Sanjay K; Jani, Omkar

    2015-07-01

    Chemically-derived graphene have been synthesized by modified Hummers method and reduced using sodium borohydride. To explore the potential for photovoltaic applications, graphene/p-silicon (Si) heterojunction devices were fabricated using a simple and cost effective technique called spin coating. The SEM analysis shows the formation of graphene oxide (GO) flakes which become smooth after reduction. The absence of oxygen containing functional groups, as observed in FT-IR spectra, reveals the reduction of GO, i.e., reduced graphene oxide (rGO). It was further confirmed by Raman analysis, which shows slight reduction in G-band intensity with respect to D-band. Hall effect measurement confirmed n-type nature of rGO. Therefore, an effort has been made to simu- late rGO/p-Si heterojunction device by using the one-dimensional solar cell capacitance software, considering the experimentally derived parameters. The detail analysis of the effects of Si thickness, graphene thickness and temperature on the performance of the device has been presented. PMID:26373050

  11. Role of environmental chemicals, processed food derivatives, and nutrients in the induction of carcinogenesis.

    PubMed

    Persano, Luca; Zagoura, Dimitra; Louisse, Jochem; Pistollato, Francesca

    2015-10-15

    In recent years it has been hypothesized that cancer stem cells (CSCs) are the actual driving force of tumor formation, highlighting the need to specifically target CSCs to successfully eradicate cancer growth and recurrence. Particularly, the deregulation of physiological signaling pathways controlling stem cell proliferation, self-renewal, differentiation, and metabolism is currently considered as one of the leading determinants of cancer formation. Given their peculiar, slow-dividing phenotype and their ability to respond to multiple microenvironmental stimuli, stem cells appear to be more susceptible to genetic and epigenetic carcinogens, possibly undergoing mutations resulting in tumor formation. In particular, some animal-derived bioactive nutrients and metabolites known to affect the hormonal milieu, and also chemicals derived from food processing and cooking, have been described as possible carcinogenic factors. Here, we review most recent literature in this field, highlighting how some environmental toxicants, some specific nutrients and their secondary products can induce carcinogenesis, possibly impacting stem cells and their niches, thus causing tumor growth. PMID:26176180

  12. Chemical looping combustion of biomass-derived syngas using ceria-supported oxygen carriers.

    PubMed

    Huang, H B; Aisyah, L; Ashman, P J; Leung, Y C; Kwong, C W

    2013-07-01

    Cu, Ni and Fe oxides supported on ceria were investigated for their performance as oxygen carriers during the chemical looping combustion of biomass-derived syngas. A complex gas mixture containing CO, H2, CO2, CH4 and other hydrocarbons was used to simulate the complex fuel gas environment derived from biomass gasification. Results show that the transfer of the stored oxygen into oxidants for the supported Cu and Ni oxides at 800°C for the combustion of syngas was effective (>85%). The unsupported Cu oxide showed high oxygen carrying capacity but particle sintering was observed at 800°C. A reaction temperature of 950°C was required for the supported Fe oxides to transfer the stored oxygen into oxidants effectively. Also, for the complex fuel gas environment, the supported Ni oxide was somewhat effective in reforming CH4 and other light hydrocarbons into CO, which may have benefits for the reduction of tar produced during biomass pyrolysis. PMID:23711944

  13. Poromechanics Parameters of Fluid-Saturated Chemically Active Fibrous Media Derived from a Micromechanical Approach

    PubMed Central

    Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette

    2014-01-01

    The authors have derived macroscale poromechanics parameters for chemically active saturated fibrous media by combining microstructure-based homogenization with Hill's volume averaging. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill's Lemmas. The advantage of this approach is that the resultant continuum model assumes a form suited to study porous materials, while retaining the effect of discrete fiber deformation. As a result, the model is able to predict the influence of microscale phenomena such as fiber buckling on the overall behavior, and in particular, on the poromechanics constants. The significance of the approach is demonstrated using the effect of drainage and fiber nonlinearity on monotonic compressive stress-strain behavior. The model predictions conform to the experimental observations for articular cartilage. The method can potentially be extended to other porous materials such as bone, clays, foams, and concrete. PMID:25419475

  14. Responses of human adipose-derived mesenchymal stem cells to chemical microenvironment of the intervertebral disc

    PubMed Central

    2012-01-01

    Background Human adipose-derived mesenchymal stem cells (ADMSCs) may be ideal source of cells for intervertebral disc (IVD) regeneration, but the harsh chemical microenvironment of IVD may significantly influence the biological and metabolic vitality of ADMSCs and impair their repair potential. This study aimed to investigate the viability, proliferation and the expression of main matrix proteins of ADMSCs in the chemical microenvironment of IVD under normal and degeneration conditions. Methods ADMSCs were harvested from young (aged 8-12 years, n = 6) and mature (aged 33-42 years, n = 6) male donors and cultured under standard condition and IVD-like conditions (low glucose, acidity, high osmolarity, and combined conditions) for 2 weeks. Cell viability was measured by annexin V-FITC and PI staining and cell proliferation was measured by MTT assay. The expression of aggrecan and collagen-I was detected by real-time quantitative polymerase chain reaction and Western blot analysis. Results IVD-like glucose condition slightly inhibited cell viability, but increased the expression of aggrecan. In contrast, IVD-like osmolarity, acidity and the combined conditions inhibited cell viability and proliferation and the expression of aggrecan and collagen-I. ADMSCs from young and mature donors exhibited similar responses to the chemical microenvironments of IVD. Conclusion IVD-like low glucose is a positive factor but IVD-like high osmolarity and low pH are deleterious factors that affect the survival and biological behaviors of ADMSCs. These findings may promote the translational research of ADMSCs in IVD regeneration for the treatment of low back pain. PMID:22424131

  15. Electrocatalytic processing of renewable biomass-derived compounds for production of chemicals, fuels and electricity

    NASA Astrophysics Data System (ADS)

    Xin, Le

    The dual problems of sustaining the fast growth of human society and preserving the environment for future generations urge us to shift our focus from exploiting fossil oils to researching and developing more affordable, reliable and clean energy sources. Human beings had a long history that depended on meeting our energy demands with plant biomass, and the modern biorefinery technologies realize the effective conversion of biomass to production of transportation fuels, bulk and fine chemicals so to alleviate our reliance on fossil fuel resources of declining supply. With the aim of replacing as much non-renewable carbon from fossil oils with renewable carbon from biomass as possible, innovative R&D activities must strive to enhance the current biorefinery process and secure our energy future. Much of my Ph.D. research effort is centered on the study of electrocatalytic conversion of biomass-derived compounds to produce value-added chemicals, biofuels and electrical energy on model electrocatalysts in AEM/PEM-based continuous flow electrolysis cell and fuel cell reactors. High electricity generation performance was obtained when glycerol or crude glycerol was employed as fuels in AEMFCs. The study on selective electrocatalytic oxidation of glycerol shows an electrode potential-regulated product distribution where tartronate and mesoxalate can be selectively produced with electrode potential switch. This finding then led to the development of AEMFCs with selective production of valuable tartronate or mesoxalate with high selectivity and yield and cogeneration of electricity. Reaction mechanisms of electrocatalytic oxidation of ethylene glycol and 1,2-propanediol were further elucidated by means of an on-line sample collection technique and DFT modeling. Besides electro-oxidation of biorenewable alcohols to chemicals and electricity, electrocatalytic reduction of keto acids (e.g. levulinic acid) was also studied for upgrading biomass-based feedstock to biofuels while achieving renewable electricity storage. Meanwhile, ORR that is often coupled in AEMFCs on the cathode was investigated on non-PGM electrocatalyst with comparable activity to commercial Pt/C. The electro-biorefinery process could be coupled with traditional biorefinery operation and will play a significant role in our energy and chemical landscape.

  16. Differential reconstructed gene interaction networks for deriving toxicity threshold in chemical risk assessment

    PubMed Central

    2013-01-01

    Background Pathway alterations reflected as changes in gene expression regulation and gene interaction can result from cellular exposure to toxicants. Such information is often used to elucidate toxicological modes of action. From a risk assessment perspective, alterations in biological pathways are a rich resource for setting toxicant thresholds, which may be more sensitive and mechanism-informed than traditional toxicity endpoints. Here we developed a novel differential networks (DNs) approach to connect pathway perturbation with toxicity threshold setting. Methods Our DNs approach consists of 6 steps: time-series gene expression data collection, identification of altered genes, gene interaction network reconstruction, differential edge inference, mapping of genes with differential edges to pathways, and establishment of causal relationships between chemical concentration and perturbed pathways. A one-sample Gaussian process model and a linear regression model were used to identify genes that exhibited significant profile changes across an entire time course and between treatments, respectively. Interaction networks of differentially expressed (DE) genes were reconstructed for different treatments using a state space model and then compared to infer differential edges/interactions. DE genes possessing differential edges were mapped to biological pathways in databases such as KEGG pathways. Results Using the DNs approach, we analyzed a time-series Escherichia coli live cell gene expression dataset consisting of 4 treatments (control, 10, 100, 1000 mg/L naphthenic acids, NAs) and 18 time points. Through comparison of reconstructed networks and construction of differential networks, 80 genes were identified as DE genes with a significant number of differential edges, and 22 KEGG pathways were altered in a concentration-dependent manner. Some of these pathways were perturbed to a degree as high as 70% even at the lowest exposure concentration, implying a high sensitivity of our DNs approach. Conclusions Findings from this proof-of-concept study suggest that our approach has a great potential in providing a novel and sensitive tool for threshold setting in chemical risk assessment. In future work, we plan to analyze more time-series datasets with a full spectrum of concentrations and sufficient replications per treatment. The pathway alteration-derived thresholds will also be compared with those derived from apical endpoints such as cell growth rate. PMID:24268022

  17. Chemical synthesis and formulation design of a PEGylated vasoactive intestinal peptide derivative with improved metabolic stability.

    PubMed

    Onoue, Satomi; Matsui, Takuya; Kato, Masashi; Mizumoto, Takahiro; Liu, Baosheng; Liu, Liang; Karaki, Shin-ichiro; Kuwahara, Atsukazu; Yamada, Shizuo

    2013-06-14

    The present study aimed to design a PEGylated VIP derivative, [Arg(15, 20, 21), Leu(17)]-VIP-GRR (IK312532), with improved metabolic stability, and develop its respirable powder (RP) formulation for inhalation therapy. IK312532 was chemically conjugated with PEG (5 kDa, P5K), the physicochemical and biochemical properties of which were characterized by CD spectral analysis, binding assays, and metabolic stability. CD spectral analysis demonstrated that PEG conjugation had no impact on the conformational structure of IK312532. Although the receptor-binding activity of IK312532/P5K (IC??: 82 nM) was estimated to be ca. 30-fold less than that of IK312532 (IC??: 2.8 nM), the metabolic stability of IK312532/P5K was highly improved. The IK312532/P5K was jet-milled and blended with lactose carrier particles to provide RP formulation of IK312532/P5K (IK312532/P5K-RP). In vitro inhalation performance and in vivo pharmacological effects of the IK312532/P5K-RP in antigen-sensitized rats were also evaluated. In cascade impactor analyses, fine particle fraction of IK312532/P5K-RP was calculated to be ca. 37%. Insufflation of IK312532/P5K-RP (150 ?g of IK312532/P5K) in antigen-sensitized rats resulted in marked attenuation of inflammatory events, as evidenced by significant decreases in inflammatory biomarkers and granulocyte recruitment in pulmonary tissue 24h after the antigen challenge. From these findings, PEGylation of a VIP derivative, as well as its strategic application to the RP formulation, may be a viable approach to improve its therapeutic potential for the treatment of airway inflammatory diseases. PMID:23608612

  18. Correlation of in Vitro Cytokine Responses with the Chemical Composition of Soil-Derived Particulate Matter

    PubMed Central

    Veranth, John M.; Moss, Tyler A.; Chow, Judith C.; Labban, Raed; Nichols, William K.; Walton, John C.; Watson, John G.; Yost, Garold S.

    2006-01-01

    We treated human lung epithelial cells, type BEAS-2B, with 10–80 μg/cm2 of dust from soils and road surfaces in the western United States that contained particulate matter (PM) < 2.5 μm aerodynamic diameter. Cell viability and cytokine secretion responses were measured at 24 hr. Each dust sample is a complex mixture containing particles from different minerals mixed with biogenic and anthropogenic materials. We determined the particle chemical composition using methods based on the U.S. Environmental Protection Agency Speciation Trends Network (STN) and the National Park Service Interagency Monitoring of Protected Visual Environments (IMPROVE) network. The functionally defined carbon fractions reported by the ambient monitoring networks have not been widely used for toxicology studies. The soil-derived PM2.5 from different sites showed a wide range of potency for inducing the release of the proinflammatory cytokines interleukin-6 (IL-6) and IL-8 in vitro. Univariate regression and multivariate redundancy analysis were used to test for correlation of viability and cytokine release with the concentrations of 40 elements, 7 ions, and 8 carbon fractions. The particles showed positive correlation between IL-6 release and the elemental and pyrolyzable carbon fractions, and the strongest correlation involving crustal elements was between IL-6 release and the aluminum:silicon ratio. The observed correlations between low-volatility organic components of soil- and road-derived dusts and the cytokine release by BEAS-2B cells are relevant for investigation of mechanisms linking specific air pollution particle types with the initiating events leading to airway inflammation in sensitive populations. PMID:16507455

  19. Correlation of in vitro cytokine responses with the chemical composition of soil-derived particulate matter.

    PubMed

    Veranth, John M; Moss, Tyler A; Chow, Judith C; Labban, Raed; Nichols, William K; Walton, John C; Watson, John G; Yost, Garold S

    2006-03-01

    We treated human lung epithelial cells, type BEAS-2B, with 10-80 microg/cm2 of dust from soils and road surfaces in the western United States that contained particulate matter (PM) < 2.5 microm aerodynamic diameter. Cell viability and cytokine secretion responses were measured at 24 hr. Each dust sample is a complex mixture containing particles from different minerals mixed with biogenic and anthropogenic materials. We determined the particle chemical composition using methods based on the U.S. Environmental Protection Agency Speciation Trends Network (STN) and the National Park Service Interagency Monitoring of Protected Visual Environments (IMPROVE) network. The functionally defined carbon fractions reported by the ambient monitoring networks have not been widely used for toxicology studies. The soil-derived PM2.5 from different sites showed a wide range of potency for inducing the release of the proinflammatory cytokines interleukin-6 (IL-6) and IL-8 in vitro. Univariate regression and multivariate redundancy analysis were used to test for correlation of viability and cytokine release with the concentrations of 40 elements, 7 ions, and 8 carbon fractions. The particles showed positive correlation between IL-6 release and the elemental and pyrolyzable carbon fractions, and the strongest correlation involving crustal elements was between IL-6 release and the aluminum:silicon ratio. The observed correlations between low-volatility organic components of soil- and road-derived dusts and the cytokine release by BEAS-2B cells are relevant for investigation of mechanisms linking specific air pollution particle types with the initiating events leading to airway inflammation in sensitive populations. PMID:16507455

  20. Chemical Solution Derived Planarization Layers for Highly Aligned IBAD MgO Templates

    SciTech Connect

    Paranthaman, Mariappan Parans; Aytug, Tolga; Stan, Liliana; Jia, Quanxi; Cantoni, Claudia; Wee, Sung Hun

    2014-01-01

    The main goal of this research is to develop a chemical solution derived planarization layer to fabricate highly aligned IBAD-MgO templates for the development of high temperature superconductor (HTS) based coated conductors. The standard IBAD-MgO template needs an additional electrochemical polishing step of the mechanically polished 50- m-thick Hastelloy C-276 substrates to ensure a flat and smooth surface for subsequent growth of multi-layer buffer architectures, which include: sputtered 80-nm Al2O3; sputtered 7-nm Y2O3; IBAD 10-nm MgO; sputtered 30-nm homo-epi MgO; and sputtered 30-nm LaMnO3 (LMO) layers. We have successfully developed a solution planarization layer that removes the electrochemical polishing step and also acts as a barrier layer. Crack-free, smooth Al2O3 layers were prepared on mechanically polished Hastelloy substrates using a chemical solution process. A nearly 10-15-nm thick Al2O3 layer was formed with each coating and the coating was repeated several times to achieve the desired film thickness with intermediate heat-treatments after each coating. The Al2O3 planarization layer significantly reduced the surface roughness of the substrate. The average surface roughness value, Ra for a starting substrate was 9-10 nm. After 8 coatings of Al2O3 layer, the Ra was reduced to 2 nm. Highly aligned IBAD-MgO layers with out-of-plane and in-plane textures comparable to the standard IBAD-MgO layers were successfully deposited on top of the solution planarization Al2O3 layers with an Y2O3 nucleation layer using a reel-to-reel ion-beam sputtering system. Both homo-epi MgO and LMO layers were subsequently deposited on the IBAD-MgO layers using rf sputtering to complete the buffer stack required for the growth of HTS films. YBa2Cu3O7- (YBCO) films with a thickness of 0.8 m deposited on these IBAD-MgO templates by pulsed laser deposition showed a high self-field critical current density, Jc of 3.04 MA/cm2 at 77 K and 6.05 MA/cm2 at 65 K. These results demonstrate that a low-cost chemical-solution-based, high-throughput Al2O3 planarization layer can remove the electro-polishing step and replace sputtered Al2O3 layers for the production of high Jc YBCO-coated conductors.

  1. Antioxidant capacity and chemical profiles of Satureja montana L. Honey: hotrienol and syringyl derivatives as biomarkers.

    PubMed

    Jerkovi?, Igor; Tuberoso, Carlo I G; Marijanovi?, Zvonimir; Kranjac, Marina; Malenica-Staver, M

    2015-07-01

    The present study is focused on the antioxidant capacity and chemical profiling of eight Croatian Satureja montana L. honey samples. Among the 20 compounds obtained by headspace solid-phase microextraction (HS-SPME) and identified by GC-FID and GC/MS analyses, hotrienol was predominant (75.9-81.7%). The honey matrix volatile/semivolatile profile was investigated by ultrasonic solvent extraction (USE) followed by GC-FID and GC/MS analyses. The major compounds identified by this latter method were the sinapic-acid derivatives methyl syringate (36.2-72.8%) and syringaldehyde (2.2-43.1%). Direct, targeted HPLC-DAD analyses of the native honey samples revealed the presence of methyl syringate (7.10-39.60?mg/kg) and syringic acid (0.10-1.70?mg/kg). In addition, the total phenolic content of the samples was determined by the Folin?Ciocalteu assay (311.0-465.9?mg GAE/kg), and the antioxidant capacity was evaluated by the DPPH radical-scavenging activity (0.5-1.0?mmol TEAC/kg) and the ferric reducing antioxidant power (2.5-5.1?mmol Fe(2+) /kg). PMID:26172325

  2. Chemical Compositional, Biological, and Safety Studies of a Novel Maple Syrup Derived Extract for Nutraceutical Applications

    PubMed Central

    2015-01-01

    Maple syrup has nutraceutical potential given the macronutrients (carbohydrates, primarily sucrose), micronutrients (minerals and vitamins), and phytochemicals (primarily phenolics) found in this natural sweetener. We conducted compositional (ash, fiber, carbohydrates, minerals, amino acids, organic acids, vitamins, phytochemicals), in vitro biological, and in vivo safety (animal toxicity) studies on maple syrup extracts (MSX-1 and MSX-2) derived from two declassified maple syrup samples. Along with macronutrient and micronutrient quantification, thirty-three phytochemicals were identified (by HPLC-DAD), and nine phytochemicals, including two new compounds, were isolated and identified (by NMR) from MSX. At doses of up to 1000 mg/kg/day, MSX was well tolerated with no signs of overt toxicity in rats. MSX showed antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH) assay) and anti-inflammatory (in RAW 264.7 macrophages) effects and inhibited glucose consumption (by HepG2 cells) in vitro. Thus, MSX should be further investigated for potential nutraceutical applications given its similarity in chemical composition to pure maple syrup. PMID:24983789

  3. Chemical Characterization of Beer Aging Products Derived from Hard Resin Components in Hops (Humulus lupulus L.).

    PubMed

    Taniguchi, Yoshimasa; Yamada, Makiko; Taniguchi, Harumi; Matsukura, Yasuko; Shindo, Kazutoshi

    2015-11-25

    The bitter taste of beer originates from resins in hops (Humulus lupulus L.), which are classified into two subtypes (soft and hard). Whereas the nature and reactivity of soft-resin-derived compounds, such as ?-, ?-, and iso-?-acids, are well studied, there is only a little information on the compounds in hard resin. For this work, hard resin was prepared from stored hops and investigated for its compositional changes in an experimental model of beer aging. The hard resin contained a series of ?-acid oxides. Among them, 4'-hydroxyallohumulinones were unstable under beer storage conditions, and their transformation induced primary compositional changes of the hard resin during beer aging. The chemical structures of the products, including novel polycyclic compounds scorpiohumulinols A and B and dicyclohumulinols A and B, were determined by HRMS and NMR analyses. These compounds were proposed to be produced via proton-catalyzed cyclization reactions of 4'-hydroxyallohumulinones. Furthermore, they were more stable than their precursor 4'-hydroxyallohumulinones during prolonged storage periods. PMID:26507444

  4. Two-dimensional carbon compounds derived from graphyne with chemical properties superior to those of graphene.

    PubMed

    Zheng, Jia-Jia; Zhao, Xiang; Zhao, Yuliang; Gao, Xingfa

    2013-01-01

    Computational studies considering both thermodynamic and kinetic aspects revealed that graphyne, a carbon material that has recently been of increasing interest, favours unprecedented homogeneous "in-plane" addition reactions. The addition of dichlorocarbene to the C(sp)-C(sp) bond, a site with outstanding regioselectivity in graphyne, proceeds via a stepwise mechanism. Due to their homogeneous nature, additions occurring at C(sp)-C(sp) bonds yield structurally ordered two-dimensional carbon compounds (2DCCs). 2DCCs have electronic band structures near the Fermi level that are similar to those of graphene and are either electrically semi-conductive or metallic depending on whether the reactions break the hexagonal symmetry. Notably, 2DCCs can be further functionalised through substitution reactions with little damage to the extended ?-electron conjugation system. These results suggest that 2DCCs derived from graphyne have physical properties comparable to those of graphene and chemical properties superior to those of graphene. Therefore, 2DCCs are expected to be better suited to practical applications. PMID:23429350

  5. Chemically modified, non-anticoagulant heparin derivatives are potent galectin-3 binding inhibitors and inhibit circulating galectin-3-promoted metastasis

    PubMed Central

    Sindrewicz, Paulina; Hughes, Ashley J.; French, Neil S.; Lian, Lu-Yun; Yates, Edwin A.; Pritchard, D. Mark; Rhodes, Jonathan M.; Turnbull, Jeremy E.; Yu, Lu-Gang

    2015-01-01

    Concentrations of circulating galectin-3, a metastasis promoter, are greatly increased in cancer patients. Here we show that 2- or 6-de-O-sulfated, N-acetylated heparin derivatives are galectin-3 binding inhibitors. These chemically modified heparin derivatives inhibited galectin-3-ligand binding and abolished galectin-3-mediated cancer cell-endothelial adhesion and angiogenesis. Unlike standard heparin, these modified heparin derivatives and their ultra-low molecular weight sub-fractions had neither anticoagulant activity nor effects on E-, L- or P-selectin binding to their ligands nor detectable cytotoxicity. Intravenous injection of such heparin derivatives (with cancer cells pre-treated with galectin-3 followed by 3 subcutaneous injections of the derivatives) abolished the circulating galectin-3-mediated increase in lung metastasis of human melanoma and colon cancer cells in nude mice. Structural analysis using nuclear magnetic resonance and synchrotron radiation circular dichroism spectroscopies showed that the modified heparin derivatives bind to the galectin-3 carbohydrate-recognition domain. Thus, these chemically modified, non-anticoagulant, low-sulfated heparin derivatives are potent galectin-3 binding inhibitors with substantial potential as anti-metastasis/cancer drugs. PMID:26160844

  6. Chemically Defined and Xeno-Free Cryopreservation of Human Adipose-Derived Stem Cells

    PubMed Central

    López, Melany; Bollag, Roni J.; Yu, Jack C.; Isales, Carlos M.; Eroglu, Ali

    2016-01-01

    The stromal compartment of adipose tissue harbors multipotent cells known as adipose-derived stem cells (ASCs). These cells can differentiate into various lineages including osteogenic, chrondrogenic, adipogenic, and neurogenic; this cellular fraction may be easily obtained in large quantities through a clinically safe liposuction procedure. Therefore, ASCs offer exceptional opportunities for tissue engineering and regenerative medicine. However, current practices involving ASCs typically use fetal bovine serum (FBS)-based cryopreservation solutions that are associated with risks of immunological reactions and of transmitting infectious diseases and prions. To realize clinical applications of ASCs, serum- and xeno-free defined cryopreservation methods are needed. To this end, an animal product-free chemically defined cryopreservation medium was formulated by adding two antioxidants (reduced glutathione and ascorbic acid 2-phosphate), two polymers (PVA and ficoll), two permeating cryoprotectants (ethylene glycol and dimethylsulfoxide), a disaccharide (trehalose), and a calcium chelator (EGTA) to HEPES-buffered DMEM/F12. To limit the number of experimental groups, the concentration of trehalose, both polymers, and EGTA was fixed while the presence of the permeating CPAs and antioxidants was varied. ASCs suspended either in different versions of the defined medium or in the conventional undefined cryopreservation medium (10% dimethylsulfoxide+10% DMEM/F12+80% serum) were cooled to -70°C at 1°C/min before being plunged into liquid nitrogen. Samples were thawed either in air or in a water bath at 37°C. The presence of antioxidants along with 3.5% concentration of each penetrating cryoprotectant improved the freezing outcome to the level of the undefined cryopreservation medium, but the plating efficiency was still lower than that of unfrozen controls. Subsequently, increasing the concentration of both permeating cryoprotectants to 5% further improved the plating efficiency to the level of unfrozen controls. Moreover, ASCs cryopreserved in this defined medium retained their multipotency and chromosomal normality. These results are of significance for tissue engineering and clinical applications of stem cells. PMID:27010403

  7. Chemically and biologically-mediated fertilizing value of manure-derived biochar.

    PubMed

    Subedi, R; Taupe, N; Ikoyi, I; Bertora, C; Zavattaro, L; Schmalenberger, A; Leahy, J J; Grignani, C

    2016-04-15

    This study evaluates the potential of manure-derived biochars in promoting plant growth and enhancing soil chemical and biological properties during a 150day pot experiment. Biochars from pyrolysis of poultry litter (PL) and swine manure (SM) at 400 and 600°C, and a commonly available wood chip (WC) biochar produced at high temperature (1000°C) were incorporated to silt-loam (SL) and sandy (SY) soils on a 2% dry soil weight basis. Ryegrass was sown and moisture was adjusted to 60% water filled pore space (WFPS). The PL400 and SM400 biochars significantly increased (p<0.05) shoot dry matter (DM) yields (SL soil) and enhanced nitrogen (N), phosphorus (P) and potassium (K) uptake by the plants in both soils, compared to the Control. All biochars significantly increased the soil carbon (C) contents compared to the Control. Total N contents were significantly greater for PL400 and PL600 treatments in both soils. The dehydrogenase activity (DA) significantly increased for PL400 and SM400 treatments and was positively correlated with the volatile matter (VM) contents of the biochars, while β-glucosidase activity (GA) decreased for the same treatments in both soils. All biochars significantly shifted (p≤0.05) the bacterial community structure compared to the Control. This study suggests that pyrolysis of animal manures can produce a biochar that acts as both soil amendment and an organic fertilizer as proven by increased NPK uptake, positive liming effect and high soil nutrient availability, while WC biochar could work only in combination with fertilizers (organic as well as mineral). PMID:26851878

  8. Chemical derivation to enhance the chemical/oxidative stability of resorcinol-formaldehyde (R-F) resin

    SciTech Connect

    Hubler, T.L.; Shaw, W.J.; Brown, G.N.; Linehan, J.C.; Franz, J.A.; Hart, T.R.; Hogan, M.O.

    1996-09-01

    Tank wastes at Hanford and SRS contain highly alkaline supernate solutions of conc. Na, K nitrates with large amounts of {sup 137}Cs. It is desirable to remove and concentrate the highly radioactive fraction for vitrification. One candidate ion exchange material for removing the radiocesium is R-F resin. This report summarizes studies into synthesis and characterization of 4-derivatized R-F resins prepared in pursuit of more chemically/oxidatively robust resin. 85% 4-fluororesorcinol/15% phenol formaldehyde resin appears to have good stability in alkaline solution, although there may be some nucleophilic displacement reaction during synthesis; further studies are needed.

  9. Nanochemistry-derived Bi2WO6 nanostructures: towards production of sustainable chemicals and fuels induced by visible light.

    PubMed

    Zhang, Nan; Ciriminna, Rosaria; Pagliaro, Mario; Xu, Yi-Jun

    2014-08-01

    Low cost and easily made bismuth tungstate (Bi2WO6) could be one of the key technologies to make chemicals and fuels from biomass, atmospheric carbon dioxide and water at low cost using solar radiation as an energy source. Its narrow band gap (2.8 eV) enables ideal visible light (? > 400 nm) absorption. Yet, it is the material's shape, namely the superstructure morphology wisely created via a nanochemistry approach, which leads to better electron-hole separation and much higher photoactivity. Recent results coupled to the versatile photochemistry of this readily available semiconductor suggest that the practical application of nanochemistry-derived Bi2WO6 nanostructures for the synthesis of value-added fine chemicals and fuel production is possible. We describe progress in this important field of chemical research from a nanochemistry viewpoint, and identify opportunities for further progress. PMID:24776966

  10. Mass production of chemicals from biomass-derived oil by directly atmospheric distillation coupled with co-pyrolysis

    PubMed Central

    Zhang, Xue-Song; Yang, Guang-Xi; Jiang, Hong; Liu, Wu-Jun; Ding, Hong-Sheng

    2013-01-01

    Production of renewable commodity chemicals from bio-oil derived from fast pyrolysis of biomass has received considerable interests, but hindered by the presence of innumerable components in bio-oil. In present work, we proposed and experimentally demonstrated an innovative approach combining atmospheric distillation of bio-oil with co-pyrolysis for mass production of renewable chemicals from biomass, in which no waste was produced. It was estimated that 51.86 wt.% of distillate just containing dozens of separable organic components could be recovered using this approach. Ten protogenetic and three epigenetic compounds in distillate were qualitatively identified by gas chromatography/mass spectrometry and quantified by gas chromatography. Among them, the recovery efficiencies of acetic acid, propanoic acid, and furfural were all higher than 80 wt.%. Formation pathways of the distillate components in this process were explored. This work opens up a fascinating prospect for mass production of chemical feedstock from waste biomass. PMID:23350028

  11. Atmospheric Chemical Transport Based on High Resolution Model- Derived Winds: A Case Study

    NASA Technical Reports Server (NTRS)

    Hannan, John R.; Fuelberg, Henry E.; Thompson, Anne M.; Bieberbach, George, Jr.; Knabb, Richard D.; Kondo, Yutaka; Anderson, Bruce E.; Browell, Edward V.; Gregory, Gerald L.; Sachse, Glen; Singh, Hanwant B.

    1999-01-01

    Flight 10 of NASA's Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) extended southwest of Lajes, Azores. A variety of chemical signatures were encountered. These signatures are examined in detail, relating them to meteorological data from a high resolution numerical model having horizontal grid spacing of 30 and 90 km and 26 vertical levels. The meteorological output at hourly intervals is used to create backward trajectories from the locations of the chemical signatures. Four major categories of chemical signatures are discussed-stratospheric, lightning, continental pollution, and a transition layer. The strong stratospheric signal is encountered just south of the Azores in a region of depressed tropopause height. Three chemical signatures at different altitudes in the upper troposphere are attributed to lightning. Backward trajectories arriving at locations of these signatures are related to locations of cloud-to-ground lightning. Results show that the trajectories pass through regions of lightning 1-2 days earlier over the eastern Gulf of Mexico and off the southeast coast of the United States. The lowest leg of the flight exhibits a chemical signature consistent with continental pollution. Trajectories arriving at this signature are found to pass over the highly populated Northeast Corridor of the United States. Surface based pollution apparently is lofted to the altitudes of the trajectories by convective clouds along the East Coast that did not contain lightning. Finally, a chemical transition layer is described. Its chemical signature is intermediate to those of lightning and continental pollution. Trajectories arriving in this layer pass between the trajectories of the lightning and pollution signatures. Thus, they probably are impacted by both sources.

  12. Chemical Synthesis and Biological Activities of Novel Pleuromutilin Derivatives with Substituted Amino Moiety

    PubMed Central

    Shang, Ruofeng; Wang, Shengyu; Xu, Ximing; Yi, Yunpeng; Guo, Wenzhu; YuLiu; Liang, Jianping

    2013-01-01

    Novel pleuromutilin derivatives designed based on the structure of valnemulin were synthesized and evaluated for their in vitro antibacterial activities. These pleuromutilin derivatives with substituted amino moiety exhibited excellent activities against methicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, Escherichia coli, and Streptococcus agalactiae. Compound 5b showed the highest antibacterial activities and even exceeded tiamulin. Moreover, the docking experiments provided information about the binding model between the synthesized compounds and peptidyl transferase center (PTC) of 23S rRNA. PMID:24376551

  13. Chemical synthesis and biological activities of novel pleuromutilin derivatives with substituted amino moiety.

    PubMed

    Shang, Ruofeng; Wang, Shengyu; Xu, Ximing; Yi, Yunpeng; Guo, Wenzhu; Yuliu; Liang, Jianping

    2013-01-01

    Novel pleuromutilin derivatives designed based on the structure of valnemulin were synthesized and evaluated for their in vitro antibacterial activities. These pleuromutilin derivatives with substituted amino moiety exhibited excellent activities against methicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, Escherichia coli, and Streptococcus agalactiae. Compound 5b showed the highest antibacterial activities and even exceeded tiamulin. Moreover, the docking experiments provided information about the binding model between the synthesized compounds and peptidyl transferase center (PTC) of 23S rRNA. PMID:24376551

  14. The applicability of in vitro-derived data in hazard identification and characterisation of chemicals.

    PubMed

    Blaauboer, Bas J

    2002-07-01

    Toxicological hazard and risk assessments for chemicals presently are mainly based on highly standardised protocols for animal experimentation and exposure assessment. In this paper the possibilities are being discussed of developing systems in which the systemic (acute and chronic) toxicity of chemicals can be quantified, without the heavy reliance on animal experiments. On the basis of a chemical's structure, in vitro data on its toxicity, and biokinetic modelling a decision/flow scheme is presented. Key elements are the evaluation of chemical functionalities representing structural alerts for toxic actions, the construction of biokinetic models on the basis of non-animal data (e.g. tissue-blood partition coefficients (PCs), in vitro biotransformation parameters), tests or batteries of tests for determining basal cytotoxicity and more specific tests for evaluating tissue- or organ toxicity. It is concluded that such a flow chart is a useful tool for different steps in the toxicological hazard and risk assessment, especially for those forms of toxicity for which validated in vitro and other non-animal tests have already been developed. PMID:21782605

  15. Influence of pecan-derived biochar on chemical properties of a Norfolk loamy sand soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sandy, Coastal Plain soils in the Southeastern USA are low (0.3 to 2%) in soil organic carbon contents (SOC) due to high soil temperatures, abundant rainfall, and a low physico-chemical protection of organic substances. Consequently, the soils have poor soil fertility characteristics. A strategy to ...

  16. Chemicals derived from pyrolysis bio-oils as antioxidants in fuels and lubricants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Softwood and hardwood lignins and hardwood were pyrolyzed to produce bio-oils to produce lignin-derived bio-oils of which phenols were the major component. These bio-oils were extracted with alkali to yield a range of lignin-related phenols having molecular weights (MWs) from 110 to 344. When tested...

  17. Transformations of biomass-derived platform molecules: from high added-value chemicals to fuels via aqueous-phase processing.

    PubMed

    Serrano-Ruiz, Juan Carlos; Luque, Rafael; Seplveda-Escribano, Antonio

    2011-11-01

    Global warming issues and the medium-term depletion of fossil fuel reserves are stimulating researchers around the world to find alternative sources of energy and organic carbon. Biomass is considered by experts the only sustainable source of energy and organic carbon for our industrial society, and it has the potential to displace petroleum in the production of chemicals and liquid transportation fuels. However, the transition from a petroleum-based economy to one based on biomass requires new strategies since the petrochemical technologies, well-developed over the last century, are not valid to process the biomass-derived compounds. Unlike petroleum feedstocks, biomass derived platform molecules possess a high oxygen content that gives them low volatility, high solubility in water, high reactivity and low thermal stability, properties that favour the processing of these resources by catalytic aqueous-phase technologies at moderate temperatures. This tutorial review is aimed at providing a general overview of processes, technologies and challenges that lie ahead for a range of different aqueous-phase transformations of some of the key biomass-derived platform molecules into liquid fuels for the transportation sector and related high added value chemicals. PMID:21713268

  18. Disruption of BASIGIN decreases lactic acid export and sensitizes non-small cell lung cancer to biguanides independently of the LKB1 status

    PubMed Central

    Floch, Renaud Le; Moura, Conceio Souto

    2015-01-01

    Most cancers rely on aerobic glycolysis to generate energy and metabolic intermediates. To maintain a high glycolytic rate, cells must efficiently export lactic acid through the proton-coupled monocarboxylate transporters (MCT1/4). These transporters require a chaperone, CD147/BASIGIN (BSG) for trafficking to the plasma membrane and function. To validate the key role of these transporters in lung cancer, we first analysed the expression of MCT1/4 and BSG in 50 non-small lung cancer (NSCLC) cases. These proteins were specifically upregulated in tumour tissues. We then disrupted BSG in three NSCLC cell lines (A549, H1975 and H292) via Zinc-Finger Nucleases. The three homozygous BSG?/? cell lines displayed a low MCT activity (10- to 5-fold reduction, for MCT1 and MCT4, respectively) compared to wild-type cells. Consequently, the rate of glycolysis, compared to the wild-type counterpart, was reduced by 2.0- to 3.5-fold, whereas the rate of respiration was stimulated in BSG?/? cell lines. Both wild-type and BSG-null cells were extremely sensitive to the mitochondria inhibitor metformin/phenformin in normoxia. However, only BSG-null cells, independently of their LKB1 status, remained sensitive to biguanides in hypoxia in vitro and tumour growth in nude mice. Our results demonstrate that inhibiting glycolysis by targeting lactic acid export sensitizes NSCLC to phenformin. PMID:25894929

  19. Disruption of BASIGIN decreases lactic acid export and sensitizes non-small cell lung cancer to biguanides independently of the LKB1 status.

    PubMed

    Granja, Sara; Marchiq, Ibtissam; Le Floch, Renaud; Moura, Conceição Souto; Baltazar, Fátima; Pouysségur, Jacques

    2015-03-30

    Most cancers rely on aerobic glycolysis to generate energy and metabolic intermediates. To maintain a high glycolytic rate, cells must efficiently export lactic acid through the proton-coupled monocarboxylate transporters (MCT1/4). These transporters require a chaperone, CD147/BASIGIN (BSG) for trafficking to the plasma membrane and function.To validate the key role of these transporters in lung cancer, we first analysed the expression of MCT1/4 and BSG in 50 non-small lung cancer (NSCLC) cases. These proteins were specifically upregulated in tumour tissues. We then disrupted BSG in three NSCLC cell lines (A549, H1975 and H292) via 'Zinc-Finger Nucleases'. The three homozygous BSG-/- cell lines displayed a low MCT activity (10- to 5-fold reduction, for MCT1 and MCT4, respectively) compared to wild-type cells. Consequently, the rate of glycolysis, compared to the wild-type counterpart, was reduced by 2.0- to 3.5-fold, whereas the rate of respiration was stimulated in BSG-/- cell lines. Both wild-type and BSG-null cells were extremely sensitive to the mitochondria inhibitor metformin/phenformin in normoxia. However, only BSG-null cells, independently of their LKB1 status, remained sensitive to biguanides in hypoxia in vitro and tumour growth in nude mice. Our results demonstrate that inhibiting glycolysis by targeting lactic acid export sensitizes NSCLC to phenformin. PMID:25894929

  20. Identification of human-derived volatile chemicals that interfere with attraction of Aedes aegypti mosquitoes.

    PubMed

    Logan, James G; Birkett, Michael A; Clark, Suzanne J; Powers, Stephen; Seal, Nicola J; Wadhams, Lester J; Mordue Luntz, A Jennifer; Pickett, John A

    2008-03-01

    It is known that human individuals show different levels of attractiveness to mosquitoes. In this study, we investigated the chemical basis for low attractiveness. We recorded behaviors of Aedes aegypti toward the hands of human volunteers and toward the volatile chemicals produced by their bodies. Some individuals, and their corresponding volatiles, elicited low upwind flight, relative attraction, and probing activity. Analyzing the components by gas chromatography coupled to electrophysiological recordings from the antennae of Aedes aegypti, enabled the location of 33 physiologically relevant compounds. The results indicated that higher levels of specific compounds may be responsible for decreased "attractiveness." In behavioral experiments, five of the compounds caused a significant reduction in upwind flight of Aedes aegypti to attractive human hands. Thus, unattractiveness of individuals may result from a repellent, or attractant "masking," mechanism. PMID:18306972

  1. Electron impact and chemical ionization mass spectral analysis of a volatile uranyl derivative

    SciTech Connect

    Reutter, D.J.; Hardy, D.R.

    1981-01-01

    Quadrupole mass spectral analysis of the volatile uranium ligand complex bis (1,1,1,5,5,5-hexafluoro-2,4-pentanedionato) dioxouranium-di-n-butyl sulfoxide is described utilizing electron impact (EI) and methane chemical ionization (CI) ion sources. All major ions are tentatively identified and the potential usefulness of this complex for determining uranium isotope /sup 235/U//sup 238/U abundance is demonstrated.

  2. Protein Structural Information Derived from NMR Chemical Shift with the Neural Network Program TALOS-N

    PubMed Central

    Shen, Yang; Bax, Ad

    2015-01-01

    Summary Chemical shifts are obtained at the first stage of any protein structural study by NMR spectroscopy. Chemical shifts are known to be impacted by a wide range of structural factors and the artificial neural network based TALOS-N program has been trained to extract backbone and sidechain torsion angles from 1H, 15N and 13C shifts. The program is quite robust, and typically yields backbone torsion angles for more than 90% of the residues, and sidechain χ1 rotamer information for about half of these, in addition to reliably predicting secondary structure. The use of TALOS-N is illustrated for the protein DinI, and torsion angles obtained by TALOS-N analysis from the measured chemical shifts of its backbone and 13Cβ nuclei are compared to those seen in a prior, experimentally determined structure. The program is also particularly useful for generating torsion angle restraints, which then can be used during standard NMR protein structure calculations. PMID:25502373

  3. Use of terrestrial field studies in the derivation of bioaccumulation potential of chemicals

    USGS Publications Warehouse

    van den Brink, Nico W.; Arblaster, Jennifer A.; Bowman, Sarah R.; Conder, Jason M.; Elliott, John E.; Johnson, Mark S.; Muir, Derek C.G.; Natal-da-Luz, Tiago; Rattner, Barnett A.; Sample, Bradley E.; Shore, Richard F.

    2016-01-01

    Field-based studies are an essential component of research addressing the behavior of organic chemicals, and a unique line of evidence that can be used to assess bioaccumulation potential in chemical registration programs and aid in development of associated laboratory and modeling efforts. To aid scientific and regulatory discourse on the application of terrestrial field data in this manner, this article provides practical recommendations regarding the generation and interpretation of terrestrial field data. Currently, biota-to-soil-accumulation factors (BSAFs), biomagnification factors (BMFs), and bioaccumulation factors (BAFs) are the most suitable bioaccumulation metrics that are applicable to bioaccumulation assessment evaluations and able to be generated from terrestrial field studies with relatively low uncertainty. Biomagnification factors calculated from field-collected samples of terrestrial carnivores and their prey appear to be particularly robust indicators of bioaccumulation potential. The use of stable isotope ratios for quantification of trophic relationships in terrestrial ecosystems needs to be further developed to resolve uncertainties associated with the calculation of terrestrial trophic magnification factors (TMFs). Sampling efforts for terrestrial field studies should strive for efficiency, and advice on optimization of study sample sizes, practical considerations for obtaining samples, selection of tissues for analysis, and data interpretation is provided. Although there is still much to be learned regarding terrestrial bioaccumulation, these recommendations provide some initial guidance to the present application of terrestrial field data as a line of evidence in the assessment of chemical bioaccumulation potential and a resource to inform laboratory and modeling efforts.

  4. Parameter estimation in stochastic chemical kinetic models using derivative free optimization and bootstrapping

    PubMed Central

    Srivastava, Rishi; Rawlings, James B.

    2014-01-01

    Recent years have seen increasing popularity of stochastic chemical kinetic models due to their ability to explain and model several critical biological phenomena. Several developments in high resolution fluorescence microscopy have enabled researchers to obtain protein and mRNA data on the single cell level. The availability of these data along with the knowledge that the system is governed by a stochastic chemical kinetic model leads to the problem of parameter estimation. This paper develops a new method of parameter estimation for stochastic chemical kinetic models. There are three components of the new method. First, we propose a new expression for likelihood of the experimental data. Second, we use sample path optimization along with UOBYQA-Fit, a variant of of Powells unconstrained optimization by quadratic approximation, for optimization. Third, we use a variant of Efrons percentile bootstrapping method to estimate the confidence regions for the parameter estimates. We apply the parameter estimation method in an RNA dynamics model of E. coli. We test the parameter estimates obtained and the confidence regions in this model. The testing of the parameter estimation method demonstrates the efficiency, reliability, and accuracy of the new method. PMID:24920866

  5. Efficiency of stepwise magnetic-chemical site assessment for fly ash derived heavy metal pollution

    NASA Astrophysics Data System (ADS)

    Cao, Liwan; Appel, Erwin; Rösler, Wolfgang; Magiera, Tadeusz

    2015-11-01

    Previous works revealed a close relationship between magnetic susceptibility (MS) and heavy metal (HM) contents originating from industrial sources. However, despite general statements on the usefulness of magnetic mapping, the benefit of this procedure for geochemistry was not quantified yet. We present a study on fly ash pollution in soil around a coal-burning power plant complex and simulate a stepwise approach of magnetic pre-screening and subsequent targeted sampling for chemical analysis. The aim of this study is not to discuss correlations between MS and HM, but to show that a combined stepwise magnetic-chemical approach is the most efficient way for outlining HM contamination. In order to provide quantitative evidence, we explored map similarities of spatial HM distributions based on magnetochemical data and chemical data only. We determined 3-D triangular planes defined by categorized HM values at the sampling coordinates and calculated the average dihedral angle of the normal vectors as a similarity result. The study shows that the `Targeted' HM map (selection of 30 sites based magnetic pre-screening) has a higher similarity with the `True' Pollution HM map (85 sites) than HM maps resulting from site selections (30 sites) without using magnetic pre-screening information.

  6. Physical and chemical characterization of biochars derived from different agricultural residues

    NASA Astrophysics Data System (ADS)

    Jindo, K.; Mizumoto, H.; Sawada, Y.; Sanchez-Monedero, M. A.; Sonoki, T.

    2014-12-01

    Biochar is widely recognized as an efficient tool for carbon sequestration and soil fertility. The understanding of its chemical and physical properties, which are strongly related to the type of the initial material used and pyrolysis conditions, is crucial to identify the most suitable application of biochar in soil. A selection of organic wastes with different characteristics (e.g., rice husk (RH), rice straw (RS), wood chips of apple tree (Malus pumila) (AB), and oak tree (Quercus serrata) (OB)) were pyrolyzed at different temperatures (400, 500, 600, 700, and 800 °C) in order to optimize the physicochemical properties of biochar as a soil amendment. Low-temperature pyrolysis produced high biochar yields; in contrast, high-temperature pyrolysis led to biochars with a high C content, large surface area, and high adsorption characteristics. Biochar obtained at 600 °C leads to a high recalcitrant character, whereas that obtained at 400 °C retains volatile and easily labile compounds. The biochar obtained from rice materials (RH and RS) showed a high yield and unique chemical properties because of the incorporation of silica elements into its chemical structure. The biochar obtained from wood materials (AB and OB) showed high carbon content and a high absorption character.

  7. Antibacterial activity of plumbagin derivative-rich Plumbago indica root extracts and chemical stability.

    PubMed

    Kaewbumrung, Sermwut; Panichayupakaranant, Pharkphoom

    2014-01-01

    The extraction studies and a one-step purification of the crude extract of Plumbago indica using silica-gel vacuum chromatography provided a plumbagin derivative-rich P. indica root extract (PPE). The PPE was standardised to contain total plumbagin derivatives not less than 13% w/w. Antibacterial activities of the standardised PPE and three naphthoquinones, plumbagin, elliptinone and 3,3'-biplumbagin, against Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis were evaluated by using the microdilution assay. The bactericidal activities of the PPE against these bacteria were much stronger than those of elliptinone and 3,3'-biplumbagin and almost equal to those of plumbagin. Stability of the PPE was determined under various conditions through a period of four months. The PPE was stable over a period of four months when stored as a dried powder but only in a well-closed container protected from light under 4 2C. PMID:24483166

  8. Spectroscopic and quantum chemical studies on the structure of 2-arylquinoline-4(1 H)-thione derivatives

    NASA Astrophysics Data System (ADS)

    Mphahlele, Malose J.; El-Nahas, Ahmed M.; El-Gogary, Tarek M.

    2004-03-01

    The geometries of the title compounds were probed in solution, solid and gas states using spectroscopic methods, X-ray crystallography and quantum chemical techniques. The exclusive existence of the NH-4-thiones in solution (NMR and PCM-B3LYP(MP2)/6-31+G(d) calculations) and solid state (FT-IR and X-ray) is also corroborated by comparison of their spectroscopic data with those of the corresponding 2-aryl-1-methylquinoline-4(1 H)-thione derivatives. The co-existence of the quinoline-4-thione and quinoline-4-thiol (4-mercaptoquinoline) isomers in the gas phase is confirmed by mass spectrometry and the preponderance of the 4-thiol is supported by quantum chemical techniques (PM3, MP2 and B3LYP).

  9. Tautomeric 2-arylquinolin-4(1 H)-one derivatives- spectroscopic, X-ray and quantum chemical structural studies

    NASA Astrophysics Data System (ADS)

    Mphahlele, Malose J.; El-Nahas, Ahmed M.

    2004-01-01

    A convenient method for the synthesis of 2-aryl-1-methylquinolin-4(1 H)-ones is described. Spectroscopic and X-ray crystallographic techniques as well as quantum chemical calculations have been used to probe the structure of potentially tautomeric 2-arylquinolin-4(1 H)-ones in solution phase, gas phase and solid state. The exclusive NH-4-oxo nature of the title compounds in solution phase (NMR) and solid state (IR and X-ray) is also corroborated by comparison of their spectroscopic data with those of the corresponding 2-aryl-1-methylquinolin-4(1 H)-one and 2-aryl-4-methoxyquinoline derivatives. Results from mass spectrometric analysis confirm the coexistence of the 4-quinolinone and 4-hydroxyquinoline isomers in the gas phase and this is supported by quantum chemical computations.

  10. Brain-derived neurotrophic factor as an indicator of chemical neurotoxicity: an animal-free CNS cell culture model.

    PubMed

    Woehrling, Elizabeth K; Hill, Eric J; Nagel, David; Coleman, Michael D

    2013-12-01

    Recent changes to the legislation on chemicals and cosmetics testing call for a change in the paradigm regarding the current 'whole animal' approach for identifying chemical hazards, including the assessment of potential neurotoxins. Accordingly, since 2004, we have worked on the development of the integrated co-culture of post-mitotic, human-derived neurons and astrocytes (NT2.N/A), for use as an in vitro functional central nervous system (CNS) model. We have used it successfully to investigate indicators of neurotoxicity. For this purpose, we used NT2.N/A cells to examine the effects of acute exposure to a range of test chemicals on the cellular release of brain-derived neurotrophic factor (BDNF). It was demonstrated that the release of this protective neurotrophin into the culture medium (above that of control levels) occurred consistently in response to sub-cytotoxic levels of known neurotoxic, but not non-neurotoxic, chemicals. These increases in BDNF release were quantifiable, statistically significant, and occurred at concentrations below those at which cell death was measureable, which potentially indicates specific neurotoxicity, as opposed to general cytotoxicity. The fact that the BDNF immunoassay is non-invasive, and that NT2.N/A cells retain their functionality for a period of months, may make this system useful for repeated-dose toxicity testing, which is of particular relevance to cosmetics testing without the use of laboratory animals. In addition, the production of NT2.N/A cells without the use of animal products, such as fetal bovine serum, is being explored, to produce a fully-humanised cellular model. PMID:24512234

  11. Characterization of Nitrogen-Containing Species in Coal and Petroleum-Derived Products by Ammonia Chemical Ionization-High Resolution Mass Spectrometry

    SciTech Connect

    Veloski, Garret A.; Lynn, Ronald J.; Sprecher, Richard F.

    1997-01-01

    A coal-derived light distillate and a petroleum-derived residuum have been studied by high resolution mass spectrometry using both low-pressure ammonia chemical ionization and low-voltage electron impact ionization. A mass calibration mixture for use with ammonia chemical ionization has been developed. Selective ionization of the basic nitrogen-containing compounds by ammonia chemical ionization and compound type characterization of the resulting quasi-molecular species has been demonstrated. Several homologous series of nitrogen-containing compounds were identified in a basic extract by electron impact ionization and compared with quasimolecular analogs identified by ammonia chemical ionization.

  12. Use of terrestrial field studies in the derivation of bioaccumulation potential of chemicals.

    PubMed

    van den Brink, Nico W; Arblaster, Jennifer A; Bowman, Sarah R; Conder, Jason M; Elliott, John E; Johnson, Mark S; Muir, Derek Cg; Natal-da-Luz, Tiago; Rattner, Barnett A; Sample, Bradley E; Shore, Richard F

    2016-01-01

    Field-based studies are an essential component of research addressing the behavior of organic chemicals, and a unique line of evidence that can be used to assess bioaccumulation potential in chemical registration programs and aid in development of associated laboratory and modeling efforts. To aid scientific and regulatory discourse on the application of terrestrial field data in this manner, this article provides practical recommendations regarding the generation and interpretation of terrestrial field data. Currently, biota-to-soil-accumulation factors (BSAFs), biomagnification factors (BMFs), and bioaccumulation factors (BAFs) are the most suitable bioaccumulation metrics that are applicable to bioaccumulation assessment evaluations and able to be generated from terrestrial field studies with relatively low uncertainty. Biomagnification factors calculated from field-collected samples of terrestrial carnivores and their prey appear to be particularly robust indicators of bioaccumulation potential. The use of stable isotope ratios for quantification of trophic relationships in terrestrial ecosystems needs to be further developed to resolve uncertainties associated with the calculation of terrestrial trophic magnification factors (TMFs). Sampling efforts for terrestrial field studies should strive for efficiency, and advice on optimization of study sample sizes, practical considerations for obtaining samples, selection of tissues for analysis, and data interpretation is provided. Although there is still much to be learned regarding terrestrial bioaccumulation, these recommendations provide some initial guidance to the present application of terrestrial field data as a line of evidence in the assessment of chemical bioaccumulation potential and a resource to inform laboratory and modeling efforts. Integr Environ Assess Manag 2016;12:135-145. © 2015 SETAC. PMID:26436822

  13. Chemical derivatives of a small molecule deubiquitinase inhibitor have antiviral activity against several RNA viruses.

    PubMed

    Gonzalez-Hernandez, Marta J; Pal, Anupama; Gyan, Kofi E; Charbonneau, Marie-Eve; Showalter, Hollis D; Donato, Nicholas J; O'Riordan, Mary; Wobus, Christiane E

    2014-01-01

    Most antiviral treatment options target the invading pathogen and unavoidably encounter loss of efficacy as the pathogen mutates to overcome replication restrictions. A good strategy for circumventing drug resistance, or for pathogens without treatment options, is to target host cell proteins that are utilized by viruses during infection. The small molecule WP1130 is a selective deubiquitinase inhibitor shown previously to successfully reduce replication of noroviruses and some other RNA viruses. In this study, we screened a library of 31 small molecule derivatives of WP1130 to identify compounds that retained the broad-spectrum antiviral activity of the parent compound in vitro but exhibited improved drug-like properties, particularly increased aqueous solubility. Seventeen compounds significantly reduced murine norovirus infection in murine macrophage RAW 264.7 cells, with four causing decreases in viral titers that were similar or slightly better than WP1130 (1.9 to 2.6 log scale). Antiviral activity was observed following pre-treatment and up to 1 hour postinfection in RAW 264.7 cells as well as in primary bone marrow-derived macrophages. Treatment of the human norovirus replicon system cell line with the same four compounds also decreased levels of Norwalk virus RNA. No significant cytotoxicity was observed at the working concentration of 5 M for all compounds tested. In addition, the WP1130 derivatives maintained their broad-spectrum antiviral activity against other RNA viruses, Sindbis virus, LaCrosse virus, encephalomyocarditis virus, and Tulane virus. Thus, altering structural characteristics of WP1130 can maintain effective broad-spectrum antiviral activity while increasing aqueous solubility. PMID:24722666

  14. Fabrication of large-area arrays of hybrid nanostructures on polymer-derived chemically patterned surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoying; Nepal, Dhriti; Biswas, Sushmita; Park, Kyoungweon; Vaia, Richard; Nealey, Paul; Air Force Research Laboratories Collaboration; University of Chicago Team

    2014-03-01

    The precise placement and assembly of nanoparticles (NPs) into large-area nanostructure arrays will allow for the design and implementation of advanced nanoscale devices for applications in fields such as quantum computing, optical sensing, superlenses, photocatalysis, photovoltaics, and non-linear optics. Our work is focused on using chemically nanopatterned surfaces to fabricate arrays of hybrid nanostructures with each component of the building block at well-defined positions. The precise chemical contrast patterns with densities and resolution of features created using standard tools of lithography, polymer self-assembly, and surface functionalization allow for control of position and interparticle spacing through selective surface-particle and particle-particle interactions. We have demonstrated the assembly of NPs, including metallic NPs and semiconductor quantum dots, into arrays of hybrid structures with various geometries, such as monomers, dimers, quatrefoils, stripes, and chains. We have developed protocols to fabricate NP arrays over a variety of substrates, which allows for the design and characterization of optical and electronic nanostructures and devices to meet the requirements of various technological applications.

  15. Chemical modeling of acid-base properties of soluble biopolymers derived from municipal waste treatment materials.

    PubMed

    Tabasso, Silvia; Berto, Silvia; Rosato, Roberta; Marinos, Janeth Alicia Tafur; Ginepro, Marco; Zelano, Vincenzo; Daniele, Pier Giuseppe; Montoneri, Enzo

    2015-01-01

    This work reports a study of the proton-binding capacity of biopolymers obtained from different materials supplied by a municipal biowaste treatment plant located in Northern Italy. One material was the anaerobic fermentation digestate of the urban wastes organic humid fraction. The others were the compost of home and public gardening residues and the compost of the mix of the above residues, digestate and sewage sludge. These materials were hydrolyzed under alkaline conditions to yield the biopolymers by saponification. The biopolymers were characterized by 13C NMR spectroscopy, elemental analysis and potentiometric titration. The titration data were elaborated to attain chemical models for interpretation of the proton-binding capacity of the biopolymers obtaining the acidic sites concentrations and their protonation constants. The results obtained with the models and by NMR spectroscopy were elaborated together in order to better characterize the nature of the macromolecules. The chemical nature of the biopolymers was found dependent upon the nature of the sourcing materials. PMID:25658795

  16. Biocomposites from waste derived biochars: Mechanical, thermal, chemical, and morphological properties.

    PubMed

    Das, Oisik; Sarmah, Ajit K; Bhattacharyya, Debes

    2016-03-01

    To identify a route for organic wastes utilisation, biochar made from various feedstocks (landfill pine saw dust, sewage sludge, and poultry litter) and at diverse pyrolysis conditions, were collected. These biochars were used to fabricate wood and polypropylene biocomposites with a loading level of 24 mass%. The composites were tested for their mechanical, chemical, thermal, morphological, and fire properties. The poultry litter biochar biocomposite, with highest ash content, was found to have high values of tensile/flexural strength, tensile/flexural modulus, and impact strength, compared to other composites. In general, addition of all the biochars enhanced the tensile/flexural moduli of the composites. The crystal structure of polypropylene in the composite was intact after the incorporation of all the biochars. The final chemical and crystal structure of the composite were an additive function of the individual components. The biochar particles along with wood acted as nucleating agents for the recrystallization of polypropylene in composite. Each component in the composites was found to decompose individually under thermal regime. The electron microscopy revealed the infiltration of polypropylene into the biochar pores and a general good dispersion in most composites. The poultry litter composite was found to have lower heat release rate under combustion regime. PMID:26724232

  17. Chemical Modeling of Acid-Base Properties of Soluble Biopolymers Derived from Municipal Waste Treatment Materials

    PubMed Central

    Tabasso, Silvia; Berto, Silvia; Rosato, Roberta; Tafur Marinos, Janeth Alicia; Ginepro, Marco; Zelano, Vincenzo; Daniele, Pier Giuseppe; Montoneri, Enzo

    2015-01-01

    This work reports a study of the proton-binding capacity of biopolymers obtained from different materials supplied by a municipal biowaste treatment plant located in Northern Italy. One material was the anaerobic fermentation digestate of the urban wastes organic humid fraction. The others were the compost of home and public gardening residues and the compost of the mix of the above residues, digestate and sewage sludge. These materials were hydrolyzed under alkaline conditions to yield the biopolymers by saponification. The biopolymers were characterized by 13C NMR spectroscopy, elemental analysis and potentiometric titration. The titration data were elaborated to attain chemical models for interpretation of the proton-binding capacity of the biopolymers obtaining the acidic sites concentrations and their protonation constants. The results obtained with the models and by NMR spectroscopy were elaborated together in order to better characterize the nature of the macromolecules. The chemical nature of the biopolymers was found dependent upon the nature of the sourcing materials. PMID:25658795

  18. Identification of persisten anionic surfactant-derived chemicals in sewage effluent and groundwater

    USGS Publications Warehouse

    Field, J.A.; Leenheer, J.A.; Thorn, K.A.; Barber, L.B., II; Rostad, C.; Macalady, D.L.; Daniel, S.R.

    1992-01-01

    Preparative isolation and fractionation procedures coupled with spectrometric analyses were used to identify surfactant-derived contaminants in sewage effluent and sewage-contaminated groundwater from a site located on Cape Cod, Massachusetts. Anionic surfactants and their biodegradation intermediates were isolated from field samples by ion exchange and fractionated by solvent extraction and adsorption chromatography. Fractions were analyzed by 13C nuclear magnetic resonance spectrometry and gas chromatography-mass spectrometry. Carboxylated residues of alkylphenol polyethoxylate surfactants were detected in sewage effluent and contaminated groundwater. Linear alkylbenzenesulfonates (LAS) were identified in sewage effluent and groundwater. Groundwater LAS composition suggested preferential removal of select isomers and homologs due to processes of biodegradation and partitioning. Tetralin and indane sulfonates (DATS), alicyclic analogs of LAS, were also identified in field samples. Although DATS are a minor portion of LAS formulations, equivalent concentrations of LAS and DATS in groundwater suggested persistence of alicyclic contaminant structures over those of linear structure. Sulfophenyl-carboxylated (SPC) LAS biodegradation intermediates were determined in sewage effluent and groundwater. Homolog distributions suggested that SPC containing 3-10 alkyl-chain carbons persist during infiltration and groundwater transport. Surfactant-derived residues detected in well F300-50 groundwater have a minimum residence time in the range of 2.7-4.6 yr. LAS detected in groundwater at 500 m from infiltration has been stable over an estimated 50-500 half lives.

  19. Chemical synthesis, in vitro acetohydroxyacid synthase (AHAS) inhibition, herbicidal activity, and computational studies of isatin derivatives.

    PubMed

    Wang, Jianguo; Tan, Haizhong; Li, Yonghong; Ma, Yi; Li, Zhengming; Guddat, Luke W

    2011-09-28

    Acetohydroxyacid synthase (AHAS) catalyzes the first common step in the biosynthesis of the branched-chain amino acids. As a result of its metabolic importance in plants, it is a target for many commercial herbicides. Virtual screening analysis inspired the evaluation of 19 commercially available isatin analogues and 13 newly synthesized isatin derivatives as novel AHAS inhibitors and for their herbicidal activity. The best compound demonstrated 95% inhibition of the activity of Arabidopsis thaliana AHAS at a concentration of 100 mg L(-1), whereas the herbicidal activities of three compounds reached 50% inhibition at a concentration of 10 mg L(-1) using the rape root growth test. CoMFA contour models were established to understand the structure-activity relationships for this class of AHAS inhibitor. The compounds were docked to the active site cavity of A. thaliana AHAS using FlexX, and the dominant binding mode was consistent with frontier molecular orbital from DFT calculations. This is the first comprehensive study of isatin derivatives as AHAS inhibitors and provides a valuable starting point for the design of new herbicides. PMID:21838297

  20. Oxygen carrier development for chemical looping combustion of coal derived synthesis gas

    SciTech Connect

    Siriwardane, R.V.; Chaudhari, K.; Zinn, A.N.; Simonyi, T.; Robinson, Clark; Poston, J.A.

    2006-09-01

    In the present work, NETL researchers have studied chemical looping combustion (CLC) with an oxygen carrier NiO/bentonite (60 wt.% NiO) for the IGCC systems utilizing simulated synthesis gas. Multi cycle CLC was conducted with NiO/Bentonite in TGA at atmospheric pressure and in a high pressure reactor in a temperature range between 700-900°C. Global reaction rates of reduction and oxidation as a function of conversion were calculated for all oxidation-reduction cycles utilizing the TGA data. The effect of particle size of the oxygen carrier on CLC was studied for the size between 20-200 mesh. The multi cycle CLC tests conducted in a high pressure packed bed flow reactor indicated constant total production of CO2 from fuel gas at 800°C and 900°C and full consumption of hydrogen during the reaction.

  1. Direct Chemical Vapor Deposition-Derived Graphene Glasses Targeting Wide Ranged Applications.

    PubMed

    Sun, Jingyu; Chen, Yubin; Priydarshi, Manish Kr; Chen, Zhang; Bachmatiuk, Alicja; Zou, Zhiyu; Chen, Zhaolong; Song, Xiuju; Gao, Yanfeng; Rümmeli, Mark H; Zhang, Yanfeng; Liu, Zhongfan

    2015-09-01

    Direct growth of graphene on traditional glasses is of great importance for various daily life applications. We report herein the catalyst-free atmospheric-pressure chemical vapor deposition approach to directly synthesizing large-area, uniform graphene films on solid glasses. The optical transparency and sheet resistance of such kinds of graphene glasses can be readily adjusted together with the experimentally tunable layer thickness of graphene. More significantly, these graphene glasses find a broad range of real applications by enabling the low-cost construction of heating devices, transparent electrodes, photocatalytic plates, and smart windows. With a practical scalability, the present work will stimulate various applications of transparent, electrically and thermally conductive graphene glasses in real-life scenarios. PMID:26305883

  2. Chemical Characteristics, Synthetic Methods, and Biological Potential of Quinazoline and Quinazolinone Derivatives

    PubMed Central

    2014-01-01

    The heterocyclic fused rings quinazoline and quinazolinone have drawn a huge consideration owing to their expanded applications in the field of pharmaceutical chemistry. Quinazoline and quinazolinone are reported for their diversified biological activities and compounds with different substitutions bring together to knowledge of a target with understanding of the molecule types that might interact with the target receptors. Quinazolines and quinazolinones are considered as an important chemical for the synthesis of various physiological significance and pharmacological utilized molecules. Quinazolines and quinazolinone are a large class of biologically active compounds that exhibited broad spectrum of biological activities such as anti-HIV, anticancer, antifungal, antibacterial, antimutagenic, anticoccidial, anticonvulsant, anti-inflammatory, antidepressant, antimalarial, antioxidant, antileukemic, and antileishmanial activities and other activities. Being considered as advantaged scaffold, the alteration is made with different substituent. PMID:25692041

  3. Assimilation of satellite-derived NO2 data into a chemical transport model

    NASA Astrophysics Data System (ADS)

    Silver, Jeremy; Brandt, Jrgen; Hvidberg, Martin; Frydendall, Jan

    2010-05-01

    The Danish Eulerian Hemispheric Model (DEHM) is a three-dimensional chemical transport model that can simulate emission, transport, diffusion, chemistry and deposition processes of air pollutant species in the atmosphere. A data assimilation (DA) module was added to DEHM, to assimilate estimates of tropospheric NO2 concentrations. The observations were obtained from the Ozone Monitoring Instrument (OMI) aboard the NASA satellite Aura. The assimilation schemed was based on statistical interpolation. We conducted several experiments, modifying the parameterisation of the background and observation error covariance matrices. Results from these experiments were compared with an independent data set: ground-based measurements of NO2 and O3 from the European Monitoring and Evaluation Programme. Despite the simplicity of the DA scheme, it substantially improved the accuracy of predicted ground-level concentrations compared to those calculated without DA. Furthermore, after applying the DA module, temporal variation in NO2 concentrations was more accurately modelled by DEHM.

  4. Fluid flow in the Rotorua geothermal field derived from isotopic and chemical data

    SciTech Connect

    Stewart, M.K.; Lyon, G.L.; Robinson, B.W. ); Glover, R.B. )

    1992-04-01

    A wide variety of isotopic and chemical measurements on geothermal fluids from shallow wells at Rotorua have given the following interpretations: The Rotorua field comprises one geothermal system; a primary upflow of (outgassed) alkali chloride water extends from northeast Whakarewarewa to Ngapuna and under Lake Rotorua (east side of the system). At the southern end a secondary upflow discharges dilute alkali chloride water; a second major upflow at Kuirau-Ohinmutu discharges chloride-bicarbonate waters formed by dilution of the primary water and reaction with rock; boiling primary water flows from the eastern upflow zone under confining sediments into aquifers in Rotorua Rhyolite containing chloride-bicarbonate waters in the central region; tritium-bearing groundwater penetrates from overlying aquifers in the sediment into the saddle area between the rhyolite domes or along the crest of the southern rhyolite dome and flows northeast into the northern dome.

  5. Physical and chemical characterizations of biochars derived from different agricultural residues

    NASA Astrophysics Data System (ADS)

    Jindo, K.; Mizumoto, H.; Sawada, Y.; Sanchez-Monedero, M. A.; Sonoki, T.

    2014-08-01

    Biochar has received large attention as a strategy to tackle against carbon emission. Not only carbon fixation has been carried out but also other merits for agricultural application due to unique physical and chemical character such as absorption of contaminated compounds in soil, trapping ammonia and methane emission from compost, and enhancement of fertilizer quality. In our study, different local waste feed stocks (rice husk, rice straw, wood chips of apple tree (Malus Pumila) and oak tree (Quercus serrata)), in Aomori, Japan, were utilized for creating biochar with different temperature (400-800 °C). Concerning to the biochar production, the pyrolysis of lower temperature had more biochar yield than higher temperature pyrolysis process. On the contrary, surface areas and adsorption characters have been increased as increasing temperature. The proportions of carbon content in the biochars also increased together with increased temperatures. Infrared-Fourier spectra (FT-IR) and 13C-NMR were used to understand carbon chemical compositions in our biochars, and it was observed that the numbers of the shoulders representing aromatic groups, considered as stable carbon structure appeared as the temperature came closer to 600 °C, as well as in FT-IR. In rice materials, the peak assigned to SiO2, was observed in all biochars (400-800 °C) in FT-IR. We suppose that the pyrolysis at 600 °C creates the most recalcitrant character for carbon sequestration, meanwhile the pyrolysis at 400 °C produces the superior properties as a fertilizer by retaining volatile and easily labile compounds which promotes soil microbial activities.

  6. Microbial production of amino acids and derived chemicals: synthetic biology approaches to strain development.

    PubMed

    Wendisch, Volker F

    2014-12-01

    Amino acids are produced at the multi-million-ton-scale with fermentative production of l-glutamate and l-lysine alone being estimated to amount to more than five million tons in the year 2013. Metabolic engineering constantly improves productivities of amino acid producing strains, mainly Corynebacterium glutamicum and Escherichia coli strains. Classical mutagenesis and screening have been accelerated by combination with intracellular metabolite sensing. Synthetic biology approaches have allowed access to new carbon sources to realize a flexible feedstock concept. Moreover, new pathways for amino acid production as well as fermentative production of non-native compounds derived from amino acids or their metabolic precursors were developed. These include dipeptides, ?,?-diamines, ?,?-diacids, keto acids, acetylated amino acids and ?-amino acids. PMID:24922334

  7. The optical properties and quantum chemical calculations of thienyl and furyl derivatives of pyrene.

    PubMed

    Idzik, Krzysztof R; Cywi?ski, Piotr J; Kuznik, Wojciech; Frydel, Jaroslaw; Licha, Tobias; Ratajczyk, Tomasz

    2015-09-21

    A detailed electrochemical, photophysical and theoretical study is presented for various new thienyl and furyl derivatives of pyrene. Their optical properties are described based on UV-VIS absorption and both steady-state and time-resolved fluorescence spectroscopy. DFT and TDDFT calculations are also presented to support experimental data. The calculations results show that HOMO-LUMO orbitals are delocalized uniformly between aromatic core and aryl substituents. Good electrochemical stability of thienyl and furyl hybrids of pyrene confirm their potential application for light emitting electrochemical cells or spintronics mainly due to their beneficial optical and charge transport properties in electrochromic devices. In order to demonstrate this potential, an OLED device is presented. Synthesized compounds included in this OLED device both facilitate electron transport and act as a light emitting layer. PMID:26257127

  8. Isolation and partial chemical characterization of macrophage-derived neutrophil chemotactic factor

    PubMed Central

    Dias-Baruffi, M.; Cunha, F. Q.; Ferreira, S. H.

    1995-01-01

    Macrophages stimulated with lipopolysaccharide (LPS) release a factor (MNCF; macrophage-derived neutrophil chemotactic factor) which induces neutrophil migration in vivo and in vitro. The in vivo chemotactic activity of crude MNCF is not affected by pretreating the animals with dexamethasone, an uncommon characteristic which discriminates MNCF from known chemotactic cytokines. We purified MNCF by affinity chromatography of the supernatant from LPS-stimulated macrophages on immobilized D-galactose, followed by gel filtration of the sugar-binding material on Superdex 75. The activity was eluted in the volume corresponding to a MW of 54 kDa. SDS–PAGE of this preparation revealed a single band, also corresponding to a 54 kDa protein. MNCF is an acidic protein (pI < 4) as shown by chromatofocussing. Like the crude MNCF, the homogeneous protein induced neutrophil migration in vitro as well as in vivo. This was not modified by dexamethasone pretreatment. PMID:18475648

  9. Surface Chemical Gradient Affects the Differentiation of Human Adipose-Derived Stem Cells via ERK1/2 Signaling Pathway.

    PubMed

    Liu, Xujie; Shi, Shengjun; Feng, Qingling; Bachhuka, Akash; He, Wei; Huang, Qianli; Zhang, Ranran; Yang, Xing; Vasilev, Krasimir

    2015-08-26

    To understand the role of surface chemistry on cell behavior and the associated molecular mechanisms, we developed and utilized a surface chemical gradient of amine functional groups by carefully adjusting the gas composition of 1,7-octadiene (OD) and allylamine (AA) of the plasma phase above a moving substrate. The chemical gradient surface used in the present work shows an increasing N/C ratio and wettability from the OD side toward the AA side with no change in surface topography. Under standard culture conditions (with serum), human adipose-derived stem cells (hASCs) adhesion and spreading area increased toward the AA side of the gradient. However, there were no differences in cell behavior in the absence of serum. These results, supported by the trends in proteins adsorption on the gradient surface, demonstrated that surface chemistry affects the response of hASCs through cell-adhesive serum proteins, rather than interacting directly with the cells. The expression of p-ERK and the osteogenic differentiation increased toward the AA side of the gradient, while adipogenic differentiation decreased in the same direction; however, when the activation of ERK1/2 was blocked by PD98059, the levels of osteogenic or adipogenic differentiation on different regions of the chemical gradient were the same. This indicates that ERK1/2 may be an important downstream signaling pathway of surface chemistry directed stem cell fate. PMID:26237746

  10. Textural and chemical properties of swine-manure-derived biochar pertinent to its potential use as a soil amendment.

    PubMed

    Tsai, Wen-Tien; Liu, Sii-Chew; Chen, Huei-Ru; Chang, Yuan-Ming; Tsai, Yi-Lin

    2012-09-01

    Biochars have received increasing attention in recent years because of their properties pertaining to soil fertility and contaminant immobilization as well as serving as carbon sinks. In this work, a series of biochars were produced from dried swine manure waste by slow pyrolysis at different temperatures (i.e., 673-1073 K). The characterization of the resulting biochars was examined for its relevance to its potential use as soil amendment. It was found that the pore properties, ash contents and pH values of all swine-manure-derived biochars basically increased as temperature increased, while the yield and nitrogen/oxygen contents decreased with increasing temperature as a result of pyrolytic volatilization during pyrolysis. From the organic and inorganic elements analyses, the manure-derived biochar was rich in soil nutrients such as N, P, Ca, Mg, and K. Furthermore, the pore, surface and chemical properties were also consistent with the observations of the SEM-EDS, XRD and FTIR. This result suggested that the mesoporous manure-derived biochar could be used as an excellent medium to soil environment. PMID:22743180

  11. Methylsilane derived silicon carbide particle coatings produced by fluid-bed chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Miller, James Henry

    This report describes the research effort that was undertaken to develop and understand processing techniques for the deposition of both low and high density SiC coatings from a non-halide precursor, in support of the Generation IV Gas-Cooled Fast Reactor (GFR) fuel development program. The research was conducted in two phases. In the first phase, the feasibility of producing both porous SiC coatings and dense SiC coatings on surrogate fuel particles by fluidized bed chemical vapor deposition (FBCVD) using gas mixtures of methylsilane and argon was demonstrated. In the second phase, a combined experimental and modeling effort was carried out in order to gain an understanding of the deposition mechanisms that result in either porous or dense SiC coatings, depending on the coating conditions. For this second phase effort, a simplified (compared to the fluid bed) single-substrate chemical vapor deposition (CVD) system was employed. Based on the experimental and modeling results, the deposition of SiC from methylsilane is controlled by the extent of gas-phase reaction, and is therefore highly sensitive to temperature. The results show that all SiC coatings are due to the surface adsorption of species that result from gas-phase reactions. The model terms these gas-borne species embryos, and while the model does not include a prediction of coating morphology, a comparison of the model and experimental results indicates that the morphology of the coatings is controlled by the nucleation and growth of the embryos. The coating that results from small embryos (embryos with only two Si-C pairs) appears relatively dense and continuous, while the coating that results from larger embryos becomes less continuous and more nodular as embryo size increases. At some point in the growth of embryos they cease to behave as molecular species and instead behave as particles that grow by either agglomeration or by incorporation of molecular species on their surface. As these particles adhere to the substrate surface and become fixed in place by surface deposition in the interstices between adjacent particles, a low density coating consisting of these particles results.

  12. Formulation and pharmacokinetics of lipid nanoparticles of a chemically sensitive nitrogen mustard derivative: Chlorambucil.

    PubMed

    Sharma, Puneet; Ganta, Srinivas; Denny, William A; Garg, Sanjay

    2009-02-01

    Lipid nanoparticles of the cancer drug Chlorambucil (CLB) were prepared by ultrasonication, using stearic acid as the core lipid. Four types of lipid nanoparticle formulations were studied: (i) stearic acid solid lipid nanoparticles (SLN); (ii) sterically stabilized SLN with pegylated phospholipids as stabilizer; (iii) nanostructured lipid complexes with oleic acid as adjunct lipid; (iv) lipid nanocomplexes with dimethyl dioctadecyl ammonium bromide (DDAB) as surface modifier (LN). Lipid nanoparticles were characterized for particle size, assay and encapsulation efficiency, particle morphology and physico-chemical stability over 90 days. All of the formulations were physically stable, with an average particle size of 147 (+/-10)nm. The drug encapsulation efficiency (DEE) of all the formulations except LN decreased significantly over time (p<0.05), probably due to the expulsion of CLB upon crystallization. This indicated that the presence of DDAB in stearic acid nanoparticles increases DEE, preventing CLB degradation in the aqueous disperse phase. Pharmacokinetic studies of the intravenous LN formulation revealed plasma clearance kinetics were comparable to that of CLB solution (p>0.01), indicating electrostatic charge mediated clearance, as reported earlier. In tissue and tumor distribution studies, lower AUC values of CLB were observed for LN compared to CLB solution in liver, kidneys, heart and lungs. However, higher AUC values of LN formulation as compared to CLB solution (p<0.01) in tumors suggested that the presence of DDAB on the lipid nanoparticles resulted in greater accumulation of the drug in tumors. PMID:18930127

  13. Production of levulinic acid and use as a platform chemical for derived products

    SciTech Connect

    Bozell, J.J.; Moens, L.; Elliott, D.C.; Wang, Y.; Neuenscwander, G.G.; Fitzpatrick, S.W.; Bilski, R.J.; Jarnefeld, J.L.

    1999-07-01

    Levulinic acid (LA) can be produced cost effectively and in high yield from renewable feedstocks in a new industrial process. The technology is being demonstrated on a one ton/day scale at a facility in South Glens Falls, New York. Low cost LA can be used as a platform chemical for the production of a wide range of value-added products. This research has demonstrated that LA can be converted to methyltetrahydrofuran (MTHF), a solvent and fuel extender. MTHF is produced in {gt}80% molar yield via a single stage catalytic hydrogenation process. A new preparation of {delta}-aminolevulinic acid (DALA), a broad spectrum herbicide from LA has also been developed. Each step in this new process proceeds in high ({gt}80%) yield and affords DALA (as the hydrochloride salt) in greater than 90% purity, giving a process that could be commercially viable. LA is also being investigated as a starting material for the production of diphenolic acid (DPA), a direct replacement for bisphenol A.

  14. Characterisation of waste derived biochar added biocomposites: chemical and thermal modifications.

    PubMed

    Das, Oisik; Sarmah, Ajit K; Zujovic, Zoran; Bhattacharyya, Debes

    2016-04-15

    A step towards sustainability was taken by incorporating waste based pyrolysed biochar in wood and polypropylene biocomposites. The effect of biochar particles on the chemistry and thermal makeup of the composites was determined by characterising them through an array of characterisation techniques such as 3D optical profiling, X-ray diffraction, transmission electron microscopy, electron spin/nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. It was observed that addition of biochar increased the presence of free radicals in the composite while also improving its thermal conductivity. Biochar particles did not interfere with the melting behaviour of polymer in the thermal regime. However, wood and biochar acted as nucleation agents consequently increasing the crystallisation temperature. The crystal structure of polypropylene was not disrupted by biochar inclusion in composite. Transmission electron microscopy images illustrated the aggregated nature of the biochar particles at higher loading levels. Nuclear magnetic resonance studies revealed the aromatic nature of biochar and the broadening of peak intensities of composites with increasing biochar levels due to its amorphous nature and presence of free radicals. Thus, this insight into the chemical and thermal modification of biochar added composites would allow effective engineering to optimise their properties while simultaneously utilising wastes. PMID:26808404

  15. The potential of synthetic indolylquinoline derivatives for Aβ aggregation reduction by chemical chaperone activity.

    PubMed

    Chang, Kuo-Hsuan; Chiu, Ya-Jen; Chen, Shu-Ling; Huang, Chen-Hsiang; Lin, Chih-Hsin; Lin, Te-Hsien; Lee, Chi-Mei; Ramesh, Chintakunta; Wu, Chung-Hsin; Huang, Chin-Chang; Fung, Hon-Chung; Chen, Yi-Chun; Lin, Jung-Yaw; Yao, Ching-Fa; Huang, Hei-Jen; Lee-Chen, Guey-Jen; Lee, Ming-Chung; Hsieh-Li, Hsiu Mei

    2016-02-01

    Alzheimer's disease (AD) is the most prevalent form of dementia associated with progressive cognitive decline and memory loss. Extracellular β-amyloid (Aβ) is a major constituent of senile plaques, one of the pathological hallmarks of AD. Aβ deposition causes neuronal death via a number of possible mechanisms such as increasing oxidative stress. Therefore therapeutic approaches to identify novel Aβ aggregate reducers could be effective for AD treatment. Using a Trx-His-Aβ biochemical assay, we screened 11 synthetic indolylquinoline compounds, and found NC009-1, -2, -6 and -7 displaying potential to reduce Aβ aggregation. Treating Tet-On Aβ-GFP 293 cells with these compounds reduced Aβ aggregation and reactive oxygen species. These compounds also promoted neurite outgrowth in Tet-On Aβ-GFP SH-SY5Y cells. Furthermore, treatment with above compounds improved neuronal cell viability, neurite outgrowth, and synaptophysin expression level in mouse hippocampal primary culture under oligomeric Aβ-induced cytotoxicity. Moreover, the tested NC009-1 significantly ameliorated Aβ-induced inhibition of hippocampal long-term potentiation in mouse hippocampal slices. Our results demonstrate how synthetic indolylquinoline compounds are likely to work as chemical chaperones in Aβ-aggregation reduction and neuroprotection, providing insight into the possible applications of indolylquinoline compounds in AD treatment. PMID:26362358

  16. Process related effects on the chemical and toxicologic characteristics of coal derived fuels

    SciTech Connect

    Wright, C.W.; Chess, E.K.; Bean, R.M.; Mahlum, D.D.; Stewart, D.L.; Wilson, B.W.

    1986-01-01

    As a component of an ongoing program to assess the potential health effects of coal conversion materials, we have recently completed chemical and toxicologic studies of a sample set collected on selected days of a 25-day demonstration run of a catalytic two stage direct coal liquefaction (CTSL) process. There was an increase in heteroatomic, nitrogen containing polycyclic aromatic compounds (NPAC) and hydroxy-substituted PAC, compounds as the operation time of the pilot plant increased. The proportion of material which boiled above 975/sup 0/F also increased in the solids-free portion of the recycle slurry oil as pilot plant operation time increased. As anticipated from the increase in NPAC concentration during the run, the microbial mutagenic activity of selected process materials also increased as a function of run time. Likewise, the tumorigenicity of the materials produced later in the demonstration run was higher than that of those produced initially. These results support the view that catalyst deactivation during the course of the run gives rise not only to lower coal conversion, but also to increased toxicologic activity. 9 refs., 3 figs., 3 tabs.

  17. Chemical Abundances of NGC 5461 and NGC 5471 Derived from Echelle Spectrophotometry

    NASA Astrophysics Data System (ADS)

    Luridiana, V.; Esteban, C.; Peimbert, M.; Peimbert, A.

    2002-04-01

    We present high resolution spectroscopic data of the two giant extragalactic H II regions NGC 5461 and NGC 5471 in M101, which have been obtained with the 2.1-m telescope of the Observatorio Astronómico Nacional in San Pedro Martir, Baja California. We measured the intensities of several H and He recombination lines, and of forbidden lines of a large number of ions. We calculate the physical conditions in the two nebulae with a large number of diagnostics and determine their chemical abundances by applying ionization correction factors ( icf's) to the observed ionic abundances. For NGC 5461, the icf's are based on a tailored photoionization model of the region (Luridiana & Peimbert 2001), while for NGC 5471 they are computed from those predicted by a photoionization model of NGC 2363 (Luridiana, Peimbert, & Leitherer 1999), a region which is similar to NGC 5471 in the ionization structure. For both regions, the icf's are compared to those computed following the prescriptions by Mathis & Rosa (1991). Such comparison shows large discrepancies for several elements, including nitrogen, neon, and chlorine.

  18. Bioprospecting Chemical Diversity and Bioactivity in a Marine Derived Aspergillus terreus.

    PubMed

    Adpressa, Donovon A; Loesgen, Sandra

    2016-02-01

    A comparative metabolomic study of a marine derived fungus (Aspergillus terreus) grown under various culture conditions is presented. The fungus was grown in eleven different culture conditions using solid agar, broth cultures, or grain based media (OSMAC). Multivariate analysis of LC/MS data from the organic extracts revealed drastic differences in the metabolic profiles and guided our subsequent isolation efforts. The compound 7-desmethylcitreoviridin was isolated and identified, and is fully described for the first time. In addition, 16 known fungal metabolites were also isolated and identified. All compounds were elucidated by detailed spectroscopic analysis and tested for antibacterial activities against five human pathogens and tested for cytotoxicity. This study demonstrates that LC/MS based multivariate analysis provides a simple yet powerful tool to analyze the metabolome of a single fungal strain grown under various conditions. This approach allows environmentally-induced changes in metabolite expression to be rapidly visualized, and uses these differences to guide the discovery of new bioactive molecules. PMID:26880440

  19. Chemical structure and pharmacological activity of some derivatives of digitoxigenin and digoxigenin

    PubMed Central

    Brown, B. T.; Stafford, Anne; Wright, S. E.

    1962-01-01

    A series of derivatives of digitoxigenin and digoxigenin were prepared and tested for toxicity in the cat and the guinea-pig and on the isolated heart of the 48-hr chick embryo, and for inotropic activity on the cat isolated papillary muscle and the guinea-pig Langendorff heart. The order of relative potency of the compounds remained the same whether they were tested for toxicity or for positive inotropic activity. There are three molecular centres in the cardiac aglycone that are linked closely with cardiac activity. These are: (a) an OH at carbon-3 which can be combined as a glycoside, thus enhancing activity, or esterified or oxidized, producing compounds of lower activity; the maximum intensity of the inotropic response was reduced in the less potent compounds; (b) a 14-β-OH associated with a cis C-D ring junction, alteration of which abolished activity; (c) an unsaturated cyclobutenolide ring which cannot be reduced without a great decrease in activity. PMID:13873586

  20. The safety and efficacy of bacterial nanocellulose wound dressing incorporating sericin and polyhexamethylene biguanide: in vitro, in vivo and clinical studies.

    PubMed

    Napavichayanun, Supamas; Yamdech, Rungnapha; Aramwit, Pornanong

    2016-03-01

    In our previous work, we have attempted to develop a novel bacterial nanocellulose wound dressing which composed of both polyhexamethylene biguanide (PHMB) as an antimicrobial agent and sericin as an accelerative wound healing component. The loading sequence and concentration of PHMB and sericin were optimized to provide the wound dressing with the most effective antimicrobial activity and enhanced collagen production. In this study, further in vitro, in vivo, and clinical studies of this novel wound dressing were performed to evaluate its safety, efficacy, and applicability. For the in vitro cytotoxic test with L929 mouse fibroblast cells, our novel dressing was not toxic to the cells and also promoted cell migration as good as the commercially available dressing, possibly due to the component of sericin released. When implanted subcutaneously in rats, the lower inflammation response was observed for the novel dressing implanted, comparing to the commercially available dressing. This might be that the antimicrobial PHMB component of the novel dressing played a role to reduce infection and inflammation reaction. The clinical trial patch test was performed on the normal skin of healthy volunteers to evaluate the irritation effect of the dressing. Our novel dressing did not irritate the skin of any volunteers, as characterized by the normal levels of erythema and melanin and the absence of edema, papule, vesicle, and bullae. Then, the novel dressing was applied for the treatment of full-thickness wounds in rats. The wounds treated with our novel dressing showed significantly lower percentage of wound size and higher extent of collagen formation mainly due to the activity of sericin. We concluded that our novel bacterial nanocellulose incorporating PHMB and sericin was a safe and efficient wound dressing material for further investigation in the wound healing efficacy in clinic. PMID:26796543

  1. The resistance of the yeast Saccharomyces cerevisiae to the biocide polyhexamethylene biguanide: involvement of cell wall integrity pathway and emerging role for YAP1

    PubMed Central

    2011-01-01

    Background Polyhexamethylene biguanide (PHMB) is an antiseptic polymer that is mainly used for cleaning hospitals and pools and combating Acantamoeba infection. Its fungicide activity was recently shown by its lethal effect on yeasts that contaminate the industrial ethanol process, and on the PE-2 strain of Saccharomyces cerevisiae, one of the main fermenting yeasts in Brazil. This pointed to the need to know the molecular mechanism that lay behind the cell resistance to this compound. In this study, we examined the factors involved in PHMB-cell interaction and the mechanisms that respond to the damage caused by this interaction. To achieve this, two research strategies were employed: the expression of some genes by RT-qPCR and the analysis of mutant strains. Results Cell Wall integrity (CWI) genes were induced in the PHMB-resistant Saccharomyces cerevisiae strain JP-1, although they are poorly expressed in the PHMB-sensitive Saccharomyces cerevisiae PE2 strain. This suggested that PHMB damages the glucan structure on the yeast cell wall. It was also confirmed by the observed sensitivity of the yeast deletion strains, ?slg1, ?rom2, ?mkk2, ?slt2, ?knr4, ?swi4 and ?swi4, which showed that the protein kinase C (PKC) regulatory mechanism is involved in the response and resistance to PHMB. The sensitivity of the ?hog1 mutant was also observed. Furthermore, the cytotoxicity assay and gene expression analysis showed that the part played by YAP1 and CTT1 genes in cell resistance to PHMB is unrelated to oxidative stress response. Thus, we suggested that Yap1p can play a role in cell wall maintenance by controlling the expression of the CWI genes. Conclusion The PHMB treatment of the yeast cells activates the PKC1/Slt2 (CWI) pathway. In addition, it is suggested that HOG1 and YAP1 can play a role in the regulation of CWI genes. PMID:21854579

  2. Chemical-looping combustion of coal-derived synthesis gas over copper oxide oxygen carriers

    SciTech Connect

    Tian, H.; Chaudhari, K.; Simonyi, T.; Poston, J.; Liu, T.; Sanders, T.; Veser, G.; Siriwardane, R.

    2008-01-01

    CuO/bentonite and CuO-BHA nanocomposites were studied as oxygen carriers in chemical-looping combustion (CLC) of simulated synthesis gas. Global reaction rates of reduction and oxidation, as the function of reaction conversion, were calculated from 10-cycle oxidation/reduction tests utilizing thermogravimetric analysis at atmospheric pressure between 700 and 900 °C. It was found that the reduction reactions are always faster than oxidation reactions; reaction temperature and particle size do not significantly affect the reaction performance of CuO/bentonite. Multicycle CLC tests conducted in a high-pressure flow reactor showed stable reactivity for production of CO2 from fuel gas at 800 and 900 °C and full consumption of hydrogen during the reaction. Results of the tapered element oscillating microbalance showed a negative effect of pressure on the global rates of reduction-oxidation reactions at higher fractional conversions. X-ray diffraction patterns confirmed the presence of CuO in the bulk phase of the oxidized sample. Electron microanalysis showed significant morphology changes of reacted CuO/bentonite samples after the 10 oxidation-reduction cycles above 700 °C in an atmospheric thermogravimetric analyzer. The nanostructured CuO-BHA carrier also showed excellent stability and, in comparison to the CuO/bentonite system, slightly accelerated redox kinetics albeit at the expense of significantly increased complexity of manufacturing. Overall, both types of CuO carriers exhibited excellent reaction performance and thermal stability for the CLC process at 700-900 °C.

  3. Chemical-looping Combustion of Coal-derived Synthesis Gas Over Copper Oxide Oxygen Carriers

    SciTech Connect

    Tian, Hanjing; Chaudhari, K P; Simonyi, Thomas; Poston, J A; Liu, Tengfei; Sanders, Tom; Veser, Goetz; Siriwardane, R V

    2008-11-01

    CuO/bentonite and CuO-BHA nanocomposites were studied as oxygen carriers in chemical-looping combustion (CLC) of simulated synthesis gas. Global reaction rates of reduction and oxidation, as the function of reaction conversion, were calculated from 10-cycle oxidation/reduction tests utilizing thermogravimetric analysis at atmospheric pressure between 700 and 900 °C. It was found that the reduction reactions are always faster than oxidation reactions; reaction temperature and particle size do not significantly affect the reaction performance of CuO/bentonite. Multicycle CLC tests conducted in a high-pressure flow reactor showed stable reactivity for production of CO2 from fuel gas at 800 and 900 °C and full consumption of hydrogen during the reaction. Results of the tapered element oscillating microbalance showed a negative effect of pressure on the global rates of reduction-oxidation reactions at higher fractional conversions. X-ray diffraction patterns confirmed the presence of CuO in the bulk phase of the oxidized sample. Electron microanalysis showed significant morphology changes of reacted CuO/bentonite samples after the 10 oxidation-reduction cycles above 700 °C in an atmospheric thermogravimetric analyzer. The nanostructured CuO-BHA carrier also showed excellent stability and, in comparison to the CuO/bentonite system, slightly accelerated redox kinetics albeit at the expense of significantly increased complexity of manufacturing. Overall, both types of CuO carriers exhibited excellent reaction performance and thermal stability for the CLC process at 700-900 °C.

  4. Chemical-looping combustion of coal-derived synthesis gas over copper oxide oxygen carriers

    SciTech Connect

    Hanjing Tian; Karuna Chaudhari; Thomas Simonyi; James Poston; Tengfei Liu; Tom Sanders; Goetz Veser; Ranjani Siriwardane

    2008-11-15

    CuO/bentonite and CuO-BHA nanocomposites were studied as oxygen carriers in chemical-looping combustion (CLC) of simulated synthesis gas. Global reaction rates of reduction and oxidation, as the function of reaction conversion, were calculated from 10-cycle oxidation/reduction tests utilizing thermogravimetric analysis at atmospheric pressure between 700 and 900{degree}C. It was found that the reduction reactions are always faster than oxidation reactions; reaction temperature and particle size do not significantly affect the reaction performance of CuO/bentonite. Multicycle CLC tests conducted in a high-pressure flow reactor showed stable reactivity for production of CO{sub 2} from fuel gas at 800 and 900{degree}C and full consumption of hydrogen during the reaction. Results of the tapered element oscillating microbalance showed a negative effect of pressure on the global rates of reduction-oxidation reactions at higher fractional conversions. X-ray diffraction patterns confirmed the presence of CuO in the bulk phase of the oxidized sample. Electron microanalysis showed significant morphology changes of reacted CuO/bentonite samples after the 10 oxidation-reduction cycles above 700{degree}C in an atmospheric thermogravimetric analyzer. The nanostructured CuO-BHA carrier also showed excellent stability and, in comparison to the CuO/bentonite system, slightly accelerated redox kinetics albeit at the expense of significantly increased complexity of manufacturing. Overall, both types of CuO carriers exhibited excellent reaction performance and thermal stability for the CLC process at 700-900{degree}C. 48 refs., 12 figs., 8 tabs.

  5. Practical silicon deposition rules derived from silane monitoring during plasma-enhanced chemical vapor deposition

    SciTech Connect

    Bartlome, Richard De Wolf, Stefaan; Demaurex, Bénédicte; Ballif, Christophe; Amanatides, Eleftherios; Mataras, Dimitrios

    2015-05-28

    We clarify the difference between the SiH{sub 4} consumption efficiency η and the SiH{sub 4} depletion fraction D, as measured in the pumping line and the actual reactor of an industrial plasma-enhanced chemical vapor deposition system. In the absence of significant polysilane and powder formation, η is proportional to the film growth rate. Above a certain powder formation threshold, any additional amount of SiH{sub 4} consumed translates into increased powder formation rather than into a faster growing Si film. In order to discuss a zero-dimensional analytical model and a two-dimensional numerical model, we measure η as a function of the radio frequency (RF) power density coupled into the plasma, the total gas flow rate, the input SiH{sub 4} concentration, and the reactor pressure. The adjunction of a small trimethylboron flow rate increases η and reduces the formation of powder, while the adjunction of a small disilane flow rate decreases η and favors the formation of powder. Unlike η, D is a location-dependent quantity. It is related to the SiH{sub 4} concentration in the plasma c{sub p}, and to the phase of the growing Si film, whether the substrate is glass or a c-Si wafer. In order to investigate transient effects due to the RF matching, the precoating of reactor walls, or the introduction of a purifier in the gas line, we measure the gas residence time and acquire time-resolved SiH{sub 4} density measurements throughout the ignition and the termination of a plasma.

  6. Practical silicon deposition rules derived from silane monitoring during plasma-enhanced chemical vapor depositiona)

    NASA Astrophysics Data System (ADS)

    Bartlome, Richard; De Wolf, Stefaan; Demaurex, Bénédicte; Ballif, Christophe; Amanatides, Eleftherios; Mataras, Dimitrios

    2015-05-01

    We clarify the difference between the SiH4 consumption efficiency η and the SiH4 depletion fraction D, as measured in the pumping line and the actual reactor of an industrial plasma-enhanced chemical vapor deposition system. In the absence of significant polysilane and powder formation, η is proportional to the film growth rate. Above a certain powder formation threshold, any additional amount of SiH4 consumed translates into increased powder formation rather than into a faster growing Si film. In order to discuss a zero-dimensional analytical model and a two-dimensional numerical model, we measure η as a function of the radio frequency (RF) power density coupled into the plasma, the total gas flow rate, the input SiH4 concentration, and the reactor pressure. The adjunction of a small trimethylboron flow rate increases η and reduces the formation of powder, while the adjunction of a small disilane flow rate decreases η and favors the formation of powder. Unlike η, D is a location-dependent quantity. It is related to the SiH4 concentration in the plasma cp, and to the phase of the growing Si film, whether the substrate is glass or a c-Si wafer. In order to investigate transient effects due to the RF matching, the precoating of reactor walls, or the introduction of a purifier in the gas line, we measure the gas residence time and acquire time-resolved SiH4 density measurements throughout the ignition and the termination of a plasma.

  7. Microstructural, Chemical and Mechanical Characterization of Polymer-Derived Hi-Nicalon Fibers with Surface Coatings

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Chen, Yuan L.

    1998-01-01

    Room temperature tensile strengths of as-received Hi-Nicalon fibers and those having BN/SiC, p-BN/SiC, and p-B(Si)N/SiC surface coatings, deposited by chemical vapor deposition, were measured using an average fiber diameter of 13.5 microns. The Weibull statistical parameters were determined for each fiber. The average tensile strength of uncoated Hi-Nicalon on was 3.19 +/- 0.73 GPa with a Weibull modulus of 5.41. Strength of fibers coated with BN/SiC did not change. However, coat with p-BN/SiC and p-B(Si)N/SiC surface layers showed strength loss of approx. 10 and 35 percent, respectively, compared with as-received fibers. The elemental compositions of the fibers and the coatings were analyzed using scanning Auger microprobe and energy dispersive x-ray spectroscopy. The BN coating was contaminated with a large concentration of carbon and some oxygen. In contrast, p-BN, p-B(Si)N, and SiC coatings did not show any contamination. Microstructural analyses of the fibers and the coatings were done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction. Hi-Nicalon fiber consists of the P-SIC nanocrystals ranging in size from 1 to 30 nm embedded in an amorphous matrix. TEM analysis of the BN coating revealed four distinct layers with turbostatic structure. The p-BN layer was turbostratic and showed considerable preferred orientation. The p-B(Si)N was glassy and the silicon and boron were uniformly distributed. The silicon carbide coating was polycrystalline with a columnar structure along the growth direction. The p-B(Si)N/SiC coatings were more uniform, less defective and of better quality than the BN/SiC or the p-BN/SiC coatings.

  8. Amphiphilic 1-deoxynojirimycin derivatives through click strategies for chemical chaperoning in N370S Gaucher cells.

    PubMed

    Diot, Jennifer D; Garcia Moreno, Isabel; Twigg, Gabriele; Ortiz Mellet, Carmen; Haupt, Karsten; Butters, Terry D; Kovensky, José; Gouin, Sébastien G

    2011-10-01

    In Gaucher disease (GD), mutant β-glucocerebrosidases (β-GCase) that are misfolded are recognized by the quality control machinery of the endoplasmic reticulum (ER) and degraded proteolytically. Hydrophobic iminosugars can be used as pharmacological chaperones to provide an improvement in the folding of the enzyme and promote trafficking from the ER. We have developed here an efficient click procedure to tether hydrophobic substituents to N-azidopropyl-1-deoxynojirimycin. A set of 14 original iminosugars was designed and evaluated for inhibition of commercially available glucosidases. Most of the compounds were micromolar inhibitors of those enzymes. In vitro inhibition assays with the N370S β-GCase revealed that the sublibrary containing the derivatives with aromatic aglycons displayed the highest inhibitory potency. Chaperone activity of the whole set of synthetic compounds was also explored in mutant Gaucher cells. The most active compound gave a nearly 2-fold increase in enzyme activity at 20 μM, a significantly higher value than the 1.33-fold recorded for the reference compound N-nonyl-1-deoxynojirimycin (N-nonyl-DNJ). As previously reported with bicyclic sp(2)-iminosugars (Luan, Z.; Higaki, K.; Aguilar-Moncayo, M.; Ninomiya, H.; Ohno, K.; García-Moreno, M. I.; Ortiz Mellet, C.; García Fernández, J. M.; Suzuki, Y. ChemBioChem 2009, 10, 2780), in vitro inhibition of β-GCase measured for the compounds did not correlate with the cellular chaperone activity. The potency of new iminosugar chaperones is therefore not predictable from structure-activity relationships studies based on the in vitro β-GCase inhibition. PMID:21830816

  9. Physical and Chemical Properties of Cometary Dust Derived from Modeling of Mid-Infrared Imaging Observations

    NASA Astrophysics Data System (ADS)

    Sarmecanic, James Richard

    1997-12-01

    Significant constraints are placed on the physical and chemical properties of cometary dust grains by analyzing mid-infrared imaging data obtained with the UCSD 'Golden Gopher' infrared camera at the 1.5-meter telescope at Mt. Lemmon Observatory. Dust grains are modeled as Mie spheres composed of either amorphous olivine (a silicate glass) or an organic residue mixture, and the results show that the optical characteristics of the two materials are quite different. The equilibrium temperatures of organic grains are much higher than for olivine grains (for the same size grains), and their respective mid-infrared emission properties are rather distinct. The results of these calculations are applied to multi-wavelength imaging of comets C/1996 B2 Hyakutake and C/1995 O1 Hale-Bopp, and it is found that the observed thermal emission from these comets can be duplicated by emission from a mixture of olivine and organic grains. For Hyakutake, the best fit to the data is achieved using 1 ?m olivine grains and 7 ?m organic grains, with an olivine mass fraction of 10%. For Hale-Bopp the predominant grain radii are 1 ?m for olivine and 2.5 ?m for organics, with a much higher olivine mass fraction of 40%. Dynamical simulations are performed using these grains in order to interpret 11.7 ?m images of comet 109P/Swift-Tuttle taken over a three week period in November 1992. The nucleus of the comet is found to be in a simple rotational state (at least over short time-scales), undergoing prograde rotation with an obliquity of 45o 10o relative to its orbital plane. At perihelion, the angle between the rotation axis and the Sun is 115o 10o, so that the 'Southern' hemisphere of the comet is generally sunward. Assuming a spherical nucleus rotating with a period of 67.5 hours, three major emission regions on the surface are identified from the recurring jet pattern. The observed dust morphology is best simulated using a grain size distribution of the form f(a)~ a-? for grain radii in the range 0.6 < a < 10/ ?m with ? = 2.5 0.5, and using jets whose opening angles are between 50o and 80o.

  10. Synthesis and Antidiabetic Evaluation of Benzenesulfonamide Derivatives

    PubMed Central

    Hosseinzadeh, Nouraddin; Seraj, Soodeh; Bakhshi-Dezffoli, Mohamad Ebrahim; Hasani, Mohammad; Khoshneviszadeh, Mehdi; Fallah-Bonekohal, Saeed; Abdollahi, Mohammad; Foroumadi, Alireza; Shafiee, Abbas

    2013-01-01

    The complex metabolic syndrome, diabetes mellitus, is a major human health concern in the world and is estimated to affect 300 million people by the year 2025. Several drugs such as sulfonylureas and biguanides are presently available to reduce hyperglycemia in diabetes mellitus. These drugs have side effects and thus searching for a new class of compounds is essential to overcome this problems. A series of seven novel N-(4-phenylthiazol-2-yl)benzenesulfonamides derivatives were synthesized and assayed in-vivo to investigate their antidiabetic activities by streptozotocin-induced model in rat. These derivatives showed considerable biological efficacy when compared to glibenclamide, a potent and well-known antidiabetic agent, as a reference drug. Four of the compounds were effective, amongst which 13 show more prominent activity at 100 mg/Kg p.o. The experimental results are statistically significant at p < 0.05 level. PMID:24250607

  11. Impact of climate and parent material on chemical weathering in Loess-derived soils of the Mississippi River valley

    USGS Publications Warehouse

    Muhs, D.R.; Bettis, E. Arthur, III; Been, J.; McGeehin, J.P.

    2001-01-01

    Peoria Loess-derived soils on uplands east of the Mississippi River valley were studied from Louisiana to Iowa, along a south-to-north gradient of decreasing precipitation and temperature. Major element analyses of deep loess in Mississippi and Illinois show that the composition of the parent material is similar in the northern and southern parts of the valley. We hypothesized that in the warmer, wetter parts of the transect, mineral weathering should be greater than in the cooler, drier parts of the transect. Profile average values of CaO/TiO2, MgO/ TiO2, K2O/TiO2, and Na2O/TiO2, Sr/Zr, Ba/Zr, and Rb/Zr represent proxies for depletion of loess minerals such as calcite, dolomite, hornblende, mica, and plagioclase. All ratios show increases from south to north, supporting the hypothesis of greater chemical weathering in the southern part of the valley. An unexpected result is that profile average values of Al2O3/TiO2 and Fe2O3/TiO2 (proxies for the relative abundance of clay minerals) show increases from south to north. This finding, while contrary to the evidence of greater chemical weathering in the southern part of the transect, is consistent with an earlier study which showed higher clay contents in Bt horizons of loess-derived soils in the northern part of the transect. We hypothesize that soils in the northern part of the valley received fine-grained loess from sources to the west of the Mississippi River valley either late in the last glacial period, during the Holocene or both. In contrast, soils in the southern part of the valley were unaffected by such additions.

  12. Chemical hydrogels based on a hyaluronic acid-graft-?-elastin derivative as potential scaffolds for tissue engineering.

    PubMed

    Palumbo, Fabio Salvatore; Pitarresi, Giovanna; Fiorica, Calogero; Rigogliuso, Salvatrice; Ghersi, Giulio; Giammona, Gaetano

    2013-07-01

    In this work hyaluronic acid (HA) functionalized with ethylenediamine (EDA) has been employed to graft ?-elastin. In particular a HA-EDA derivative bearing 50 mol% of pendant amino groups has been successfully employed to produce the copolymer HA-EDA-g-?-elastin containing 32% w/w of protein. After grafting with ?-elastin, remaining free amino groups reacted with ethylene glycol diglycidyl ether (EGDGE) for producing chemical hydrogels, proposed as scaffolds for tissue engineering. Swelling degree, resistance to chemical and enzymatic hydrolysis, as well as preliminary biological properties of HA-EDA-g-?-elastin/EGDGE scaffold have been evaluated and compared with a HA-EDA/EGDGE scaffold. The presence of ?-elastin grafted to HA-EDA improves attachment, viability and proliferation of primary rat dermal fibroblasts and human umbilical artery smooth muscle cells. Biological performance of HA-EDA-g-?-elastin/EGDGE scaffold resulted comparable to that of a commercial collagen type I sponge (Antema), chosen as a positive control. PMID:23623066

  13. Expanding the chemical diversity of natural esters by engineering a polyketide-derived pathway into Escherichia coli.

    PubMed

    Menendez-Bravo, Simn; Comba, Santiago; Sabatini, Martn; Arabolaza, Ana; Gramajo, Hugo

    2014-07-01

    Microbial fatty acid (FA)-derived molecules have emerged as promising alternatives to petroleum-based chemicals for reducing dependence on fossil hydrocarbons. However, native FA biosynthetic pathways often yield limited structural diversity, and therefore restricted physicochemical properties, of the end products by providing only a limited variety of usually linear hydrocarbons. Here we have engineered into Escherichia coli a mycocerosic polyketide synthase-based biosynthetic pathway from Mycobacterium tuberculosis and redefined its biological role towards the production of multi-methyl-branched-esters (MBEs) with novel chemical structures. Expression of FadD28, Mas and PapA5 enzymes enabled the biosynthesis of multi-methyl-branched-FA and their further esterification to an alcohol. The high substrate tolerance of these enzymes towards different FA and alcohol moieties resulted in the biosynthesis of a broad range of MBE. Further metabolic engineering of the MBE producer strain coupled this system to long-chain-alcohol biosynthetic pathways resulting in de novo production of branched wax esters following addition of only propionate. PMID:24831705

  14. Birth of common marmoset (Callithrix jacchus) offspring derived from in vitro-matured oocytes in chemically defined medium.

    PubMed

    Tomioka, I; Takahashi, T; Shimada, A; Yoshioka, K; Sasaki, E

    2012-10-15

    Optimization of oocyte culture conditions is a crucial aspect of reproductive biology and technology. In the present study, maturation of germinal vesicle-stage marmoset oocytes were evaluated in the following media: Waymouth medium, Waymouth medium containing porcine follicular fluid (pFF) (Waymouth-pFF medium), and porcine oocyte medium (POM). Oocytes cultured in Waymouth-pFF medium had higher maturation rates to the metaphase II stage than those cultured in Waymouth medium (36.1% vs. 24.8%, respectively, P < 0.05), indicating the suitability of this medium for culturing marmoset oocytes. Hence, maturation of marmoset oocytes cultured in POM was subsequently evaluated. The rate of maturation to the metaphase I stage was significantly higher and degradation rates were significantly lower in oocytes cultured in POM than those cultured in Waymouth medium. In addition, three offspring were successfully obtained after transfer of embryos matured in chemically defined medium. Therefore, we concluded that POM was suitable for marmoset oocyte culture. Furthermore, this was apparently the first report of marmoset offspring derived from oocytes cultured in chemically defined medium. PMID:22925648

  15. Chemical Reactivity of alpha-Pinene-derived Products in the Aqueous Phase: Implications on the Fate of Organic Nitrates

    NASA Astrophysics Data System (ADS)

    Rindelaub, J. D.; Hostetler, M. A.; Lipton, M. A.; Shepson, P. B.

    2014-12-01

    The production of organic nitrates has significant atmospheric importance due to the impact on regional air quality by influencing NOx lifetimes and ozone formation. Additionally, these low volatility compounds readily partition into the particle phase and are important contributors to secondary organic aerosol. Once in the aerosol phase, organic nitrates undergo further chemical reactions that govern their fate in the atmosphere and, consequently, their impact on air quality. Recent research indicates that the presence of water on aerosol particles has a major impact on the reactivity of organic nitrates and that condensed phase hydrolysis leads to the destruction of organic nitrate species, depending on structure. Despite this knowledge, the chemical mechanisms, products, product reactivity and volatility are still uncertain, negatively impacting our understanding of aerosol phase processing and the contribution to air quality. To further understand the atmospheric impact of aerosol phase hydrolysis, we analyzed both condensed phase hydrolysis reactions involving alpha-pinene-derived standards and alpha-pinene photochemical chamber reaction filter samples, using a suite of spectroscopic and mass spectrometric techniques. We were able to measure the pH-dependent hydrolysis rate constants for several types of organic nitrates and identify specific reaction products. The chemistry involved exhibits a strong dependence on pH, providing important mechanistic clues. The results of this study will significantly contribute to our knowledge of aerosol phase chemistry and the impact on regional air quality with respect to the fate of organic nitrate species.

  16. Molecular dynamics simulation and quantum chemical calculations for the adsorption of some Azo-azomethine derivatives on mild steel

    NASA Astrophysics Data System (ADS)

    Shokry, H.

    2014-02-01

    The adsorption mechanism and inhibition performance of some Azo-azomethine derivatives [2-hydroxyphenylazo-2‧,4‧-dihydroxy-3‧-formylbenzene(Azo-1), 2-carboxyphenylazo-2‧,4‧-dihydroxy-3‧-formylbenzene (Azo-II), 2-hydroxyphenylazo-2‧,4‧-dihydroxy-3‧-{2-hydroxyphenylazomethine}(Azo-I-azomethine I) and 2-carboxyphenylazo-2‧,4‧-dihydroxy-3‧-{2-hydroxyazo methane} (Azo-II-azomethine II) on mild steel at temperatures ranging from 298 K to 333 K have been studied using molecular dynamics (MD) simulation and quantum chemical computational methods. The results obtained revealed that these molecules could effectively adsorb on Fe (0 0 1) surface and the active adsorption sites of these molecules are the nitrogen, oxygen atoms and special negatively charged carbon atoms. All the inhibitors studied had unique corrosion inhibition performance with Azo-II-azomethine II showing the highest inhibition performance at lower temperature ranges from 298 K to 313 K and Azo-II displaying the highest inhibition performance at higher temperature ranges of 323 K and 333 K. Some quantum chemical parameters and the Mulliken charge densities on the optimized structure of inhibitors were calculated using the 6-31∗G basis set method to provide further insight into the mechanism of the corrosion inhibition process. The local reactivity was analyzed through the Fukui function and condensed softness indices in order to know the possible sites of nucleophillic and electrophillic attacks.

  17. Maternally derived chemical defences are an effective deterrent against some predators of poison frog tadpoles (Oophaga pumilio)

    PubMed Central

    Stynoski, Jennifer L.; Shelton, Georgia; Stynoski, Peter

    2014-01-01

    Parents defend their young in many ways, including provisioning chemical defences. Recent work in a poison frog system offers the first example of an animal that provisions its young with alkaloids after hatching or birth rather than before. But it is not yet known whether maternally derived alkaloids are an effective defence against offspring predators. We identified the predators of Oophaga pumilio tadpoles and conducted laboratory and field choice tests to determine whether predators are deterred by alkaloids in tadpoles. We found that snakes, spiders and beetle larvae are common predators of O. pumilio tadpoles. Snakes were not deterred by alkaloids in tadpoles. However, spiders were less likely to consume mother-fed O. pumilio tadpoles than either alkaloid-free tadpoles of the red-eyed treefrog, Agalychnis callidryas, or alkaloid-free O. pumilio tadpoles that had been hand-fed with A. callidryas eggs. Thus, maternally derived alkaloids reduce the risk of predation for tadpoles, but only against some predators. PMID:24850895

  18. Design, synthesis, and physico-chemical interactions of bile acid derived dimeric phospholipid amphiphiles with model membranes.

    PubMed

    Kumar, Sandeep; Bhargava, Priyanshu; Sreekanth, Vedagopuram; Bajaj, Avinash

    2015-06-15

    Understanding of amphiphile-membrane interactions is crucial in design and development of novel amphiphiles for drug delivery, gene therapy, and biomedical applications. Structure and physico-chemical properties of amphiphiles determine their interactions with biomembranes thereby influencing their drug delivery efficacies. Here, we unravel the interactions of bile acid derived dimeric phospholipid amphiphiles with model membranes using Laurdan-based hydration, DPH-based membrane fluidity, and differential scanning calorimetry studies. We synthesized three dimeric bile acid amphiphiles where lithocholic acid, deoxycholic acid, and cholic acid are conjugated to cholic acid phospholipid using click chemistry. Interactions of these dimeric amphiphiles with model membranes showed that these amphiphiles form different structural assemblies and molecular packing in model membranes depending on the number and position of free hydroxyl groups on bile acids. We discovered that cholic acid-cholic acid dimeric phospholipid form self-assembled aggregates in model membranes without changing membrane fluidity; whereas cholic acid-deoxycholic acid derived amphiphile induces membranes fluidity and hydration of model membranes. PMID:25746193

  19. Maternally derived chemical defences are an effective deterrent against some predators of poison frog tadpoles (Oophaga pumilio).

    PubMed

    Stynoski, Jennifer L; Shelton, Georgia; Stynoski, Peter

    2014-05-01

    Parents defend their young in many ways, including provisioning chemical defences. Recent work in a poison frog system offers the first example of an animal that provisions its young with alkaloids after hatching or birth rather than before. But it is not yet known whether maternally derived alkaloids are an effective defence against offspring predators. We identified the predators of Oophaga pumilio tadpoles and conducted laboratory and field choice tests to determine whether predators are deterred by alkaloids in tadpoles. We found that snakes, spiders and beetle larvae are common predators of O. pumilio tadpoles. Snakes were not deterred by alkaloids in tadpoles. However, spiders were less likely to consume mother-fed O. pumilio tadpoles than either alkaloid-free tadpoles of the red-eyed treefrog, Agalychnis callidryas, or alkaloid-free O. pumilio tadpoles that had been hand-fed with A. callidryas eggs. Thus, maternally derived alkaloids reduce the risk of predation for tadpoles, but only against some predators. PMID:24850895

  20. Cloned calves derived from somatic cell nuclear transfer embryos cultured in chemically defined medium or modified synthetic oviduct fluid

    PubMed Central

    Hong, So Gun

    2011-01-01

    Somatic cell nuclear transfer (SCNT) is considered to be a critical tool for propagating valuable animals. To determine the productivity calves resulting from embryos derived with different culture media, enucleated oocytes matured in vitro were reconstructed with fetal fibroblasts, fused, and activated. The cloned embryos were cultured in modified synthetic oviduct fluid (mSOF) or a chemically defined medium (CDM) and developmental competence was monitored. After 7 days of culturing, the blastocysts were transferred into the uterine horn of estrus-synchronized recipients. SCNT embryos that were cultured in mSOF or CDM developed to the blastocysts stages at similar rates (26.6% vs. 22.5%, respectively). A total of 67 preimplantational stage embryos were transferred into 34 recipients and six cloned calves were born by caesarean section, or assisted or natural delivery. Survival of transferred blastocysts to live cloned calves in the mSOF and the CDM was 18.5% (to recipients), 9.6% (to blastocysts) and 42.9% (to recipients), 20.0% (to blastocysts), respectively. DNA analysis showed that all cloned calves were genetically identical to the donor cells. These results demonstrate that SCNT embryos cultured in CDM showed higher viability as judged by survival of the calves that came to term compared to blastocysts derived from mSOF cultures. PMID:21368567

  1. Optical absorption measurements and quantum-chemical simulations on 1H-pyrazolo[3,4-b]quinoline derivatives

    NASA Astrophysics Data System (ADS)

    Ko?cie?, E.; Sanetra, J.; Gondek, E.; Danel, A.; Wis?a, A.; Kityk, A. V.

    2003-11-01

    We present the results of experimental studies and quantum chemical simulation (PM3 and AM1 methods) on a new synthesized pyrazolo[3,4-b]quinoline derivatives: 1,4-diphenyl-3-methyl-, 3,4-diphenyl-1-methyl-, 1,3,4-triphenyl-, 1,3-dimethyl-4-phenyl- and 1,3,4-trimethyl-1H-pyrazolo[3,4-b]quinoline. The quantum chemical analysis reveals similarity in the absorption spectra of 1H-pyrazolo[3,4-b]quinoline and 1,3,4-trimethyl-1H-pyrazolo[3,4-b]quinoline which are characterized by four strong absorption bands in the spectral range 200-500 nm. A substitution of the methyl groups by phenyl groups causes substantial changes of the absorption spectra mainly in the spectral range 240-370 nm. We attribute these differences to additional molecular double bounding segments C?C of the substituted phenyl groups i.e., to ??? * transitions. The comparison of measured and calculated absorption spectra by quantum-chemical AM1 method manifests rather good agreement for all compounds in the part regarding the spectral positions of the first oscillator (absorption threshold). At the same time, the measured spectra reveal the considerable broadening practically of all absorption bands. We attribute these discrepancies to a strong solvent effect. By analyzing the charge density distribution we have shown that the most strongest absorption bands in the spectral region 200-270 nm are related with double bonding segments C?N (n?? * transition).

  2. Chemical stability and in vitro and clinical efficacy of a novel hybrid retinoid derivative, bis-retinamido methylpentane.

    PubMed

    Kim, Ki Hyun; Lim, Dae Gon; Lim, Jun Yeul; Kim, Nam Ah; Park, So-Hyun; Cho, Jin Hun; Shin, Beom Soo; Jeong, Seong Hoon

    2015-11-10

    The anti-aging agent, retinol, has fewer side effects and similar biological activity compared to retinoic acid. However, retinol becomes unstable when exposed to light and heat. A novel hybrid retinoid derivative, bis-retinamido methylpentane (RS-2A), was newly developed to overcome the limitations. This study evaluated the chemical stability of RS-2A under thermal and light conditions by examining degradation profiles, and assessed the in vitro biological activity, cytotoxicity, and clinical efficacy. Chemical stability and degradation profiles were investigated with HPLC and LC-MS. Especially, photo-stability of RS-2A was analyzed under various conditions, such as change of physical state and concentration, different solvents, and various excipients. For analyses of cellular activity and cytotoxicity, human dermal fibroblasts were cultured with RS-2A. To evaluate the safety and efficacy of the compound with the cellular results, RS-2A was applied to women who had moderate to severe wrinkles at the periorbital region. All of the experiments were conducted with retinol as a reference. RS-2A was more stable than retinol to thermal conditions, especially in solution. Both RS-2A and retinol were unstable to light, but RS-2A showed enhanced photo-stability with regard to concentration, more polar solvent, and addition of proper excipients. RS-2A exhibited decreased cytotoxicity and enhanced effects on collagen synthesis compared with retinol. In a clinical study, a 4-week treatment with RS-2A significantly improved the appearance of periorbital wrinkles without any side effects. The results indicate that RS-2A might have potential as an anti-aging agent for cosmeceutical preparations because of its enhanced chemical stability, biological activity, safety, and clinical efficacy. PMID:26325317

  3. Quinoxaline derivatives as corrosion inhibitors for mild steel in hydrochloric acid medium: Electrochemical and quantum chemical studies

    NASA Astrophysics Data System (ADS)

    Olasunkanmi, Lukman O.; Kabanda, Mwadham M.; Ebenso, Eno E.

    2016-02-01

    The corrosion inhibition potential of four quinoxaline derivatives namely, 1-[3-(4-methylphenyl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl]butan-1-one (Me-4-PQPB), 1-(3-(4-methoxyphenyl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl)butan-1-one (Mt-4-PQPB), 1-[3-(3-methoxyphenyl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl]butan-1-one (Mt-3-PQPB) and 1-[3-(2H-1,3-benzodioxol-5-yl)-5-(quinoxalin-6-yl)-4,5-dihydropyrazol-1-yl]butan-1-one (Oxo-1,3-PQPB) was studied for mild steel corrosion in 1 M HCl solution using electrochemical, spectroscopic techniques and quantum chemical calculations. The results of both potentiodynamic polarization and electrochemical impedance spectroscopic studies revealed that the compounds are mixed-type inhibitors and the order of corrosion inhibition efficiency at 100 ppm is Me-4-PQPB>Mt-3-PQPB>Oxo-1,3-PQPB>Mt-4-PQPB. Fourier transform infrared (FTIR) and ultraviolet-visible (UV-vis) spectroscopic analyses confirmed the presence of chemical interactions between the inhibitors and mild steel surface. The adsorption of the inhibitor molecules on mild steel surface was found to be both physisorption and chemisorption but predominantly chemisorption. The experimental data obey Langmuir adsorption isotherm. Scanning electron microscopy studies revealed the formation of protective films of the inhibitors on mild steel surface. Quantum chemical parameters obtained from density functional theory (DFT) calculations support experimental results.

  4. Roles of Chemical Complexity and Evolutionary Theory in Some Hepatic and Intestinal Enzymatic Systems in Chemical Reproducibility and Clinical Efficiency of Herbal Derivatives

    PubMed Central

    2014-01-01

    Despite the great marketing success, most physicians attribute poor efficacy to herbals. This perception is due to two situations that are an integral part of the herbal topic. The first is the poor phytochemical reproducibility obtained during the production process of herbal extracts, as herbal extracts are not always standardized in the whole manufacturing process, but only in their titer. The second problem is linked to the evolution of important enzymatic systems: cytochromes and ABC proteins. They are both enzyme classes with detoxifying properties and seem to have evolved from the molecular mould provided by active plant substances. During the evolution, as still happens today, polyphenols, saponins, terpenes, and alkaloids were ingested together with food. They do not possess any nutritional value but seem to be provided with a potential pharmacological activity. Cytochromes and ABC proteins, which evolved over time to detoxify food from vegetable chemical “actives,” now seem to limit the action of herbal derivatives. The comprehension of these 2 events may explain the origin of the widespread scepticism of physicians about herbal medicine and suggests that, after correct herbal standardization, use of antagonists of cytochromes and ABC systems will make it possible to recover their pharmacological potential. PMID:24977222

  5. Seasonal cycles in radium and barium within a subterranean estuary: Implications for groundwater derived chemical fluxes to surface waters

    NASA Astrophysics Data System (ADS)

    Gonneea, Meagan Eagle; Mulligan, Ann E.; Charette, Matthew A.

    2013-10-01

    There is increasing evidence that submarine groundwater discharge (SGD) is an important source of water and dissolved materials to the ocean. One of the primary tracers of this process is the quartet of radium isotopes (223Ra, 224Ra, 226Ra and 228Ra), whereby excess activities in surface waters can often be attributed to an input supplied via SGD. This approach requires the radium end member activity to be well constrained, however, natural variability in groundwater radium may span several orders of magnitude. Therefore, this variability is usually the main driver of uncertainties in volumetric SGD estimates. To investigate the physical and biogeochemical controls on groundwater radium activities, we conducted a three-year time series of radium and barium, a chemical analogue for radium, within the subterranean estuary of a coastal aquifer (Waquoit Bay, MA, USA). Gonneea et al. (2013) demonstrated that movement of the salinity interface within the subterranean estuary is driven by changes in the hydraulic gradient between groundwater level and sea level height. For Waquoit Bay, seasonal scale sea level change, not groundwater level, was the main driver in hydraulic gradient fluctuations. Seasonal changes in groundwater chemistry can be attributed to the resulting movement of the salinity transition zone between terrestrial and marine groundwater. Landward movement of the interface results in a large release of radium isotopes (226Ra = 1400 dpm 100 L-1) and barium (3000 nmol kg-1) associated with an increase in groundwater salinity. The magnitude of these releases cannot be explained by in situ production or weathering alone, but is likely due to salinity driven desorption from surface-bound sediment inventory. The timing of these peak concentrations is not always in phase with model-derived estimates of SGD; as a result, the groundwater concentration rather than the water flux is the main driver of Ra and Ba inputs to Waquoit Bay surface waters. The behavior of the subterranean estuary as an ion exchange reservoir has important implications for the timing and flux of various nutrients and pollutants that transit this region prior to discharge. In addition to modulating chemical fluxes via submarine groundwater discharge on seasonal time scales, transgression of the subterranean estuary may alter the input of chemicals to the ocean on decadal and longer time scales. During this study, the observed excess flux of 226Ra and Ba from the subterranean estuary can be accounted for with sorbed sediment pools and accelerating rates of sea level rise in this region.

  6. Gene expression signatures in CD34+-progenitor-derived dendritic cells exposed to the chemical contact allergen nickel sulfate

    SciTech Connect

    Schoeters, Elke . E-mail: elke.schoeters@vito.be; Nuijten, Jean-Marie; Heuvel, Rosette L. van den; Nelissen, Inge; Witters, Hilda; Schoeters, Greet E.R.; Tendeloo, Vigor F.I. van; Berneman, Zwi N.; Verheyen, Geert R.

    2006-10-01

    The detection of the sensitizing potential of chemicals is of great importance to industry. A promising in vitro alternative to the currently applied animal assays for sensitization testing makes use of dendritic cells (DCs) that have the capability to process and present antigens to naive T cells and induce their proliferation. Here, we studied changes in gene expression profiles after exposing DCs to the contact allergen nickel sulfate. CD34+-progenitor-derived DCs, initiated from 3 different donors, were exposed to 60 {mu}M nickel sulfate, during 0.5, 1, 3, 6, 12 and 24 h. cDNA microarrays were used to assess the transcriptional activity of about 11,000 genes. Significant changes in the expression of 283 genes were observed; 178 genes were up-regulated and 93 down-regulated. These genes were involved in metabolism, cell structure, immune response, transcription, signal transduction, transport, and apoptosis. No functional information was found for 74 genes. Real-time RT-PCR was used to confirm the microarray results of 12 genes. In addition, 3 DC maturation markers not present on the microarrays (DEC205, DC LAMP and CCR7) were analyzed using real-time RT-PCR and found to be up-regulated at several time points. Our data indicate that a broad range of biological processes is influenced by nickel. Some processes are clearly linked to the immune response and DC maturation, others may indicate a toxic effect of nickel.

  7. Influence of oxide impurities on the chemical tuning of the thermoelectric properties of substitution derivatives of RuIn3

    NASA Astrophysics Data System (ADS)

    Wagner-Reetz, Maik; Cardoso-Gil, Raul; Schmidt, Marcus; Grin, Yuri

    2014-07-01

    A systematic investigation on tuning the charge carrier concentration by substitution of the Ru position in RuIn3 is performed. Samples with nominal composition Ru0.95T0.05In3 (T=Re, Rh, Ir) were synthesized via liquid-solid-reaction and subsequent spark plasma sintering treatment. The chemical composition was characterized by X-ray, metallographic and microstructure analysis revealing solid solutions in the samples with Rh and Ir, whereas Re cannot be incorporated in RuIn3. Minor oxide impurities in the commercially available starting elements, the homogeneity range of RuIn3 and the redox potentials of the participating elements are the key for interpreting the observed lattice parameters and the corresponding composition. Both, substitutions with Rh or Ir and Re inclusions in RuIn3 lead independently to a significant decrease of the total thermal conductivity down to approximately one half of the value observed for binary RuIn3, prepared with commercially available starting materials. The electrical resistivity was reduced by substitution and the temperature dependence changes from semiconductor-like, for RuIn3, to metal-like in the substitution derivatives. At the same time the sign change in the thermopower at high temperatures, characteristic for binary RuIn3, is suppressed, attaining only electrons as majority carriers.

  8. Spectrophotometric determination of aminomethylbenzoic acid using sodium 1,2-naphthoquinone-4-sulfonate as the chemical derivative chromogenic reagent

    NASA Astrophysics Data System (ADS)

    Li, Quan-Min; Yang, Zhan-Jun

    2007-03-01

    A new method has been established for the determination of aminomethylbenzoic acid using sodium 1,2-naphthoquinone-4-sulfonate as the chemical derivative chromogenic reagent. This method is based on the formation of a pink compound from the reaction of aminomethylbenzoic acid and sodium 1,2-naphthoquinone-4-sulfonate. The nucleophilic substitution reaction proceeds quantitatively in pH 12.0 buffer solution. The stoichiometric ratio of the reaction, maximum absorption wavelength and the value of ?430 were 1:1, 430 nm, and 2.87 10 3 L mol -1 cm -1, respectively. Beer's law was obeyed in the range of 0.80-80 mg/L of aminomethylbenzoic acid. The data have been filled to a linear regression equation A = 0.03183 + 0.01658 C (mg/L), with a correlation coefficient of 0.9996. The detection limit is 0.11 mg/L, R.S.D. is 0.54%, and average recovery is over 99.6%. This paper further improves the determination of aminomethylbenzoic acid compared to the previous methods. The kinetic property and reaction mechanism have also been discussed. This proposed method has been successfully applied to the determination of aminomethylbenzoic acid in injection of aminomethylbenzoic acid with satisfactory results.

  9. Syntheses, spectroscopic investigation and electronic properties of two sulfonamide derivatives: A combined experimental and quantum chemical approach

    NASA Astrophysics Data System (ADS)

    Mahmood, Ayyaz; Akram, Tehmina; de Lima, Edna Barboza

    2016-03-01

    Two sulfonamides derivatives, N-phenethyl-4-methylbenzenesulfonamide (1) and N-(4-hydroxyphenethyl)-4-methylbenzenesulfonamide (2), were successfully synthesized and fully characterized using 1H NMR, 13C NMR, FT-IR spectroscopies and elemental analysis. The molecular and electronic structures of the compounds were further investigated using density functional theory calculation at B3LYP and B3PW91 functionals using 6-311++G(d,p) basis set to provide structural and spectroscopic information and guide spectral assignments. The experimental and simulated 1H NMR, 13C NMR and FT-IR spectra were compared and the accuracy was discussed. The conformational analysis was performed in order to find the most stable molecular structure of the compounds. Molecular quantities such as ionization potential, electron affinity, electronegativity, electrophilicity index and chemical hardness and softness were calculated and used as an additional molecular characteristic to predict the stability of the molecules. Electronic properties such Mullikan atomic charges, HOMO, LUMO and HOMO-LUMO energy gaps and molecular electrostatic potential maps predict the large intramolecular charge transfer within the molecules and significant substitution effects.

  10. QUANTITATION OF MONOSACCHARIDE ISOTOPIC ENRICHMENT IN PHYSIOLOGIC FLUIDS BY ELECTRON IONIZATION OR NEGATIVE CHEMICAL IONIZATION GC/MS USING DI-O-ISOPROPYLIDENE DERIVATIVES.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aldonitrile pentaacetate and other derivatives lack ions in the electron ionization (EI) spectra possessing an intact hexose structure and thus must be analyzed by chemical ionization GC/MS in order to study multiple isotopomers. We report methods for quantitation of hexose di-O-isopropylidene a...

  11. Trends and interactions of physical and bio-geo-chemical features in the Adriatic Sea as derived from satellite observations.

    PubMed

    Barale, Vittorio; Schiller, Christian; Tacchi, Ruggero; Marechal, Cecile

    2005-12-15

    Time series of satellite data, generated by the AVHRR (1981-1999), CZCS (1979-1985) and SeaWiFS (1998-2002), have been used to assess trends and interactions of physical and bio-geo-chemical features in the Adriatic Sea. The images were processed to estimate Sea Surface Temperature (SST) and Chlorophyll-like Pigment Concentration (CPC). Long-term composites and climatologies were derived, using fixed geographical grids and projections. The AVHRR data show an apparent warming trend, when plotting the sequence of seasonal cycles (monthly mean SST, averaged over the whole basin) against time, due to a steady rise of summer values. Considering 3 regions (north, central and south), split into east and west sections, the northern Adriatic shows high SST fluctuations (possibly associated with the cycle of winter cooling and summer warming, typical of the relatively shallow sub-basin), while the southern Adriatic exhibits a lower variability (possibly influenced by the periodic water incoming from, and outflowing to the Ionian Sea). During summer, an east-west gradient prevails, while during winter only a general north-south gradient can be found. The SeaWiFS-derived CPC values, distributions and trends appear to be consistent with the historical CZCS record. Persistent differences in the quantitative assessment of CPC for coastal waters is due to the use of improved algorithms, less influenced by the presence of dissolved organics and suspended sediments in the water column, for the processing of SeaWiFS data. Apparent incongruities of the space and time patterns in the SeaWiFS record with respect to the reference climatology, obtained by CZCS more than a decade before, occur chiefly when considering the spring bloom in the southern Adriatic and the summer development of the north Adriatic front. The comparison of the long-term times series of satellite data shows that there is a high correlation between patterns in the thermal field and in the colour field. This suggests that different surface waters, identified by the SST index, are also traced by different ecological features, identified by the CPC index. Both indices also show a high correlation with the classical cyclonic circulation scheme of the Adriatic Sea, proposing once again an intimate relationship between the water dynamics and its bio-geo-chemistry. PMID:16271746

  12. Production of a refined biooil derived by fast pyrolysis of chicken manure with chemical and physical characteristics close to those of fossil fuels.

    PubMed

    Monreal, Carlos M; Schnitzer, Morris

    2011-01-01

    The chemical and physical properties of raw biooils prevent their direct use in combustion engines. We processed raw pyrolytic biooil derived from chicken manure to yield a colorless refined biooil with diesel qualities. Chemical characterization of the refined biooil involved elemental and several spectroscopic analyses. The physical measurements employed were viscosity, density and heat of combustion. The elemental composition (% wt/wt) of the refined biooil was 82.7 % C, 15.3 % H, 0.2 % N and 1.8 % O, no S. Its viscosity was 0.006 Pa.s and a heat of combustion of 43 MJ kg(-1). The refined biooil fraction contains n-alkanes, ranging from n-C(14) to n-C(27), alkenes varying from C(10:1) to C(22:1), and long-chain alcohols. The refined biooil makes a good diesel fuel due to its chemical and physical properties. PMID:21749251

  13. Organic reactions for the electrochemical and photochemical production of chemical fuels from CO2--The reduction chemistry of carboxylic acids and derivatives as bent CO2 surrogates.

    PubMed

    Luca, Oana R; Fenwick, Aidan Q

    2015-11-01

    The present review covers organic transformations involved in the reduction of CO2 to chemical fuels. In particular, we focus on reactions of CO2 with organic molecules to yield carboxylic acid derivatives as a first step in CO2 reduction reaction sequences. These biomimetic initial steps create opportunities for tandem electrochemical/chemical reductions. We draw parallels between long-standing knowledge of CO2 reactivity from organic chemistry, organocatalysis, surface science and electrocatalysis. We point out some possible non-faradaic chemical reactions that may contribute to product distributions in the production of solar fuels from CO2. These reactions may be accelerated by thermal effects such as resistive heating and illumination. PMID:26022364

  14. 1H NMR chemical shift studies of pregn-5-ene-3?,20( R)-diol and pregn-5-ene-3?-ol,20-one D-glucopyranoside derivatives

    NASA Astrophysics Data System (ADS)

    Warthen, J. D.; Waters, R. M.; Oliver, J. E.

    The 1H NMR chemical shift and J value data of a series of pregn-5-ene-3?,20( R)-diol/pregn-5-ene-3?-ol, 20-one D-glucopyranosides and D-glucopyranoside derivatives are reported because of their relevance to the structure determination of pregnenediol tri- and diglucosides on tobacco hornworm eggs. Effects of various substituents at the 3?- and 20( R)-positions of the pregn-5-ene nucleus upon chemical shifts of selected protons on the pregn-5-ene nucleus are discussed. Chemical shifts of selected protons on the D-glucopyranoside nucleus/nuclei are also discussed. Differentiation between the pregn-5-ene substitution points, between anomeric glucose configurations and between anomeric protons on ?- D-glucosides at 3? and 20( R) is demonstrated. A COSY NMR analysis of the Manduca peracetylated triglucoside is utilized to show the interaction of the three anomeric ?- D-glucoside protons and to distinguish the dissimilar one.

  15. Determination of oxygen and nitrogen derivatives of polycyclic aromatic hydrocarbons in fractions of asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization.

    PubMed

    Nascimento, Paulo Cicero; Gobo, Luciana Assis; Bohrer, Denise; Carvalho, Leandro Machado; Cravo, Margareth Coutinho; Leite, Leni Figueiredo Mathias

    2015-12-01

    Liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization was used for the determination of polycyclic aromatic hydrocarbon derivatives, the oxygenated polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons, formed in asphalt fractions. Two different methods have been developed for the determination of five oxygenated and seven nitrated polycyclic aromatic hydrocarbons that are characterized by having two or more condensed aromatic rings and present mutagenic and carcinogenic properties. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all compounds. The detection limits of the methods ranged from 0.1 to 57.3 μg/L for nitrated and from 0.1 to 6.6 μg/L for oxygenated derivatives. The limits of quantification were in the range of 4.6-191 μg/L for nitrated and 0.3-8.9 μg/L for oxygenated derivatives. The methods were validated against a diesel particulate extract standard reference material (National Institute of Standards and Technology SRM 1975), and the obtained concentrations (two nitrated derivatives) agreed with the certified values. The methods were applied in the analysis of asphalt samples after their fractionation into asphaltenes and maltenes, according to American Society for Testing and Material D4124, where the maltenic fraction was further separated into its basic, acidic, and neutral parts following the method of Green. Only two nitrated derivatives were found in the asphalt sample, quinoline and 2-nitrofluorene, with concentrations of 9.26 and 2146 mg/kg, respectively, whereas no oxygenated derivatives were detected. PMID:26446274

  16. Minocycline and doxycycline, but not other tetracycline-derived compounds, protect liver cells from chemical hypoxia and ischemia/reperfusion injury by inhibition of the mitochondrial calcium uniporter

    SciTech Connect

    Schwartz, Justin; Holmuhamedov, Ekhson; Zhang, Xun; Lovelace, Gregory L.; Smith, Charles D.; Lemasters, John J.

    2013-11-15

    Minocycline, a tetracycline-derived compound, mitigates damage caused by ischemia/reperfusion (I/R) injury. Here, 19 tetracycline-derived compounds were screened in comparison to minocycline for their ability to protect hepatocytes against damage from chemical hypoxia and I/R injury. Cultured rat hepatocytes were incubated with 50 μM of each tetracycline-derived compound 20 min prior to exposure to 500 μM iodoacetic acid plus 1 mM KCN (chemical hypoxia). In other experiments, hepatocytes were incubated in anoxic Krebs–Ringer–HEPES buffer at pH 6.2 for 4 h prior to reoxygenation at pH 7.4 (simulated I/R). Tetracycline-derived compounds were added 20 min prior to reperfusion. Ca{sup 2+} uptake was measured in isolated rat liver mitochondria incubated with Fluo-5N. Cell killing after 120 min of chemical hypoxia measured by propidium iodide (PI) fluorometry was 87%, which decreased to 28% and 42% with minocycline and doxycycline, respectively. After I/R, cell killing at 120 min decreased from 79% with vehicle to 43% and 49% with minocycline and doxycycline. No other tested compound decreased killing. Minocycline and doxycycline also inhibited mitochondrial Ca{sup 2+} uptake and suppressed the Ca{sup 2+}-induced mitochondrial permeability transition (MPT), the penultimate cause of cell death in reperfusion injury. Ru360, a specific inhibitor of the mitochondrial calcium uniporter (MCU), also decreased cell killing after hypoxia and I/R and blocked mitochondrial Ca{sup 2+} uptake and the MPT. Other proposed mechanisms, including mitochondrial depolarization and matrix metalloprotease inhibition, could not account for cytoprotection. Taken together, these results indicate that minocycline and doxycycline are cytoprotective by way of inhibition of MCU. - Highlights: • Minocycline and doxycycline are the only cytoprotective tetracyclines of those tested • Cytoprotective tetracyclines inhibit the MPT and mitochondrial calcium and iron uptake. • Cytoprotective tetracyclines protect by inhibiting the MCU.

  17. Design, synthesis, characterization, quantum-chemical calculations and anti-inflammatory activity of novel series of thiophene derivatives

    NASA Astrophysics Data System (ADS)

    Helal, M. H.; Salem, M. A.; Gouda, M. A.; Ahmed, N. S.; El-Sherif, A. A.

    2015-08-01

    Interaction of 1-(4-morpholinophenyl)ethanone 1 with either malononitrile or ethyl cyanoacetate 2 afforded Knoevenagel-Cope product 3. In subsequent treatment of 3 with sulfur, the 2-aminothiophene derivatives (4a, 4b) are formed under basic conditions. The solvent-free reaction of thiophene derivative 4a with ethyl cyanoacetate afforded thieno[2,3-d][1,3]oxazine derivative 6. The base catalyzed condensation of 2-aminothiophene derivative (4a) with ethyl cyanoacetate afforded N-(thieno-2-yl) cyanoacetamide derivative 7. The latter was used to synthesize different heterocyclic derivatives comprising, pyridine and coumarin rings. Also, several substituted thieno[2,3-d]pyrimidines have been prepared from reaction of 2-aminothiophene-3-carbonitrile 4b with some electrophilic reagents. The structure of the newly compounds were confirmed on the basis of elemental analysis and spectral data. The molecular modeling of the synthesized compounds has been drawn and their molecular parameters were calculated. Also, valuable information is obtained from calculation of the molecular parameters including electronegativity, net dipole moment of the compounds, total energy, electronic energy, binding energy, HOMO and LUMO energy. Evaluation of anti-inflammatory activity of the tested compounds was performed in albino rats by producing carrageenan induced paw oedema and measuring the zone of inflammation at different time intervals i.e. 1, 2, 3 and 4 h after carrageenan injection. Results indicated that most of the tested compounds showed moderate to good activity comparable to indomethacin. Also, compound 16 with additional morpholine ring beside the thiophene ring inhibits carrageenan induced paw oedema more than the standard indomethacin drug at all the time scales studied. Thus, compound 16 is considered as a promising compound for further modification to obtain clinically useful anti-inflammatory agent.

  18. INFLUENCE OF DECOMPOSITION ON CHEMICAL PROPERTIES OF PLANT-AND MANURE-DERIVED DISSOLVED ORGANIC MATTER AND SORPTION TO GOETHITE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sorption of dissolved organic matter (DOM) plays an important role in maintaining the fertility and quality of soils in agricultural ecosystems. Few studies have examined the effects of decomposition on DOM sorption and chemical characteristics. This study investigated the sorption to goethite of ...

  19. Derivation of Tissue-specific Functional Gene Sets to Aid Transcriptomic Analysis of Chemical Impacts on the Teleost Reproductive Axis.

    EPA Science Inventory

    Oligonucleotide microarrays are a powerful tool for unsupervised analysis of chemical impacts on biological systems. However, the lack of well annotated biological pathways for many aquatic organisms, including fish, and the poor power of microarray-based analyses to detect diffe...

  20. Total synthesis approaches to natural product derivatives based on the combination of chemical synthesis and metabolic engineering.

    PubMed

    Kirschning, Andreas; Taft, Florian; Knobloch, Tobias

    2007-10-21

    Secondary metabolites are an extremely diverse and important group of natural products with industrial and biomedical implications. Advances in metabolic engineering of both native and heterologous secondary metabolite producing organisms have allowed the directed synthesis of desired novel products by exploiting their biosynthetic potentials. Metabolic engineering utilises knowledge of cellular metabolism to alter biosynthetic pathways. An important technique that combines chemical synthesis with metabolic engineering is mutasynthesis (mutational biosynthesis; MBS), which advanced from precursor-directed biosynthesis (PDB). Both techniques are based on the cellular uptake of modified biosynthetic intermediates and their incorporation into complex secondary metabolites. Mutasynthesis utilises genetically engineered organisms in conjunction with feeding of chemically modified intermediates. From a synthetic chemist's point of view the concept of mutasynthesis is highly attractive, as the method combines chemical expertise with Nature's synthetic machinery and thus can be exploited to rapidly create small libraries of secondary metabolites. However, in each case, the method has to be critically compared with semi- and total synthesis in terms of practicability and efficiency. Recent developments in metabolic engineering promise to further broaden the scope of outsourcing chemically demanding steps to biological systems. PMID:17912378

  1. Dual photonic-bandgap optical films towards the generation of photonic crystal-derived 2-dimensional chemical codes.

    PubMed

    Zhang, Jing; Yang, Shengyang; Tian, Yu; Wang, Cai-Feng; Chen, Su

    2015-07-01

    Chemical-oriented 2-dimensional (2D) optical codes were constructed for the first time by integrating bi-layer or bistriate-structure responsive photonic crystals (RPCs), which not only presents high information capacity in encoding processes, but offers a facile route to the detection of high performance sensors along with accurate analysis and anti-jamming performances. PMID:26036800

  2. [New biological active derivatives of indomethacin and acetylsalicylic acid. Synthesis, physico-chemical characterisation and structure validation].

    PubMed

    Stan, Catalina; Stefanache, Alina; Dumitrache, M

    2006-01-01

    It is well known that niflumic acid glycinamide has a good antiinflammatory action useful in gum inflammatory diseases. The objective of this study was to obtain new glycinamides of acetylsalicylic acid and indomethacin, which could have a better antiinflammatory action than niflumic acid glycinamide. The study presents the synthesis, physico-chemical characterisation and structure validation of these glycinamides. PMID:17438920

  3. Identification of volatile/semivolatile products derived from chemical remediation of cis-1,3-dichloropropene by thiosulfate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The prevalent use of soil fumigants resulted in air pollution in some agricultural regions. Our previous research showed that application of thiosulfate fertilizers at the soil surface may offer an effective and economical approach to reduce the emission of halogenated fumigants via a chemical remed...

  4. Identification of Volatile/Semi-Volatile Products Derived from Chemical Remediation of cis-1,3-Dichloropropene by Thiosulfate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The prevalent use of soil fumigants has resulted in air pollution in some agricultural regions. Our previous research showed that amendment of thiosulfate fertilizers at the soil surface may offer an effective and economical approach to reduce the emission of halogenated fumigants via a chemical rem...

  5. Carcinogenicity predictions for a group of 30 chemicals undergoing rodent cancer bioassays based on rules derived from subchronic organ toxicities.

    PubMed Central

    Lee, Y; Buchanan, B G; Rosenkranz, H S

    1996-01-01

    Rodent carcinogenicities for a group of 30 chemicals which form the subject of the Second NIEHS Predictive-Toxicology Evaluation Experiment are predicted based on their subchronic organ toxicities. Predictions are made by rules learned by the rule learning (RL) induction program. PMID:8933055

  6. Development of a pluripotent stem cell derived neuronal model to identify chemically induced pathway perturbations in relation to neurotoxicity: effects of CREB pathway inhibition.

    PubMed

    Pistollato, Francesca; Louisse, Jochem; Scelfo, Bibiana; Mennecozzi, Milena; Accordi, Benedetta; Basso, Giuseppe; Gaspar, John Antonydas; Zagoura, Dimitra; Barilari, Manuela; Palosaari, Taina; Sachinidis, Agapios; Bremer-Hoffmann, Susanne

    2014-10-15

    According to the advocated paradigm shift in toxicology, acquisition of knowledge on the mechanisms underlying the toxicity of chemicals, such as perturbations of biological pathways, is of primary interest. Pluripotent stem cells (PSCs), such as human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), offer a unique opportunity to derive physiologically relevant human cell types to measure molecular and cellular effects of such pathway modulations. Here we compared the neuronal differentiation propensity of hESCs and hiPSCs with the aim to develop novel hiPSC-based tools for measuring pathway perturbation in relation to molecular and cellular effects in vitro. Among other fundamental pathways, also, the cAMP responsive element binding protein (CREB) pathway was activated in our neuronal models and gave us the opportunity to study time-dependent effects elicited by chemical perturbations of the CREB pathway in relation to cellular effects. We show that the inhibition of the CREB pathway, using 2-naphthol-AS-E-phosphate (KG-501), induced an inhibition of neurite outgrowth and synaptogenesis, as well as a decrease of MAP2(+) neuronal cells. These data indicate that a CREB pathway inhibition can be related to molecular and cellular effects that may be relevant for neurotoxicity testing, and, thus, qualify the use of our hiPSC-derived neuronal model for studying chemical-induced neurotoxicity resulting from pathway perturbations. PMID:25150140

  7. Genomic and chemical insights into biosurfactant production by the mangrove-derived strain Bacillus safensis CCMA-560.

    PubMed

    Domingos, Daniela Ferreira; de Faria, Andreia Fonseca; de Souza Galaverna, Renan; Eberlin, Marcos Nogueira; Greenfield, Paul; Zucchi, Tiago Domingues; Melo, Itamar Soares; Tran-Dinh, Nai; Midgley, David; de Oliveira, Valria Maia

    2015-04-01

    Many Bacillus species can produce biosurfactant, although most of the studies on lipopeptide production by this genus have been focused on Bacillus subtilis. Surfactants are broadly used in pharmaceutical, food and petroleum industry, and biological surfactant shows some advantages over the chemical surfactants, such as less toxicity, production from renewable, cheaper feedstocks and development of novel recombinant hyperproducer strains. This study is aimed to unveil the biosurfactant metabolic pathway and chemical composition in Bacillus safensis strain CCMA-560. The whole genome of the CCMA-560 strain was previously sequenced, and with the aid of bioinformatics tools, its biosurfactant metabolic pathway was compared to other pathways of closely related species. Fourier transform infrared (FTIR) and high-resolution TOF mass spectrometry (MS) were used to characterize the biosurfactant molecule. B. safensis CCMA-560 metabolic pathway is similar to other Bacillus species; however, some differences in amino acid incorporation were observed, and chemical analyses corroborated the genetic results. The strain CCMA-560 harbours two genes flanked by srfAC and srfAD not present in other Bacillus spp., which can be involved in the production of the analogue gramicidin. FTIR and MS showed that B. safensis CCMA-560 produces a mixture of at least four lipopeptides with seven amino acids incorporated and a fatty acid chain with 14 carbons, which makes this molecule similar to the biosurfactant of Bacillus pumilus, namely, pumilacidin. This is the first report on the biosurfactant production by B. safensis, encompassing the investigation of the metabolic pathway and chemical characterization of the biosurfactant molecule. PMID:25586584

  8. A new cytotoxic prenylated dihydrobenzofuran derivative and other chemical constituents from the rhizomes of Atractylodes lancea DC.

    PubMed

    Duan, Jin-ao; Wang, Liuying; Qian, Shihui; Su, Shulan; Tang, Yuping

    2008-08-01

    A new prenylated dihydrobenzofuran derivative (1), was isolated from the rhizomes of Atractylodes lancea DC (Asteraceae), along with ten known compounds, including atractylenolide II (2), phi-taraxasteryl acetate (3), taraxerol acetate (4), beta-sitosterol (5), stigmasterol (6), beta-eudesmol (7), atractylenolide III (8), atractylenolide IV (9), daucosterol (10), and stigmasterol 3-O-beta-D-glucopyranoside (11). The structure of the new compound (1) was elucidated as trans-2-hydroxyisoxypropyl-3-hydroxy-7-isopentene-2,3-dihydrobenzofuran-5-carboxylic acid by the combination of 1D, 2D NMR analysis and mass spectrometry, and it was the first reported 2,3-dihydrobenzofuran derivative having a carboxyl residue at C-5 and an isopentene moiety at C-7 contemporaneously. In addition, compound 1 exhibited significant cytotoxicity against cancer cell lines HCT-116 and MKN-45. PMID:18787781

  9. Development of a pluripotent stem cell derived neuronal model to identify chemically induced pathway perturbations in relation to neurotoxicity: Effects of CREB pathway inhibition

    SciTech Connect

    Pistollato, Francesca; Louisse, Jochem; Scelfo, Bibiana; Mennecozzi, Milena; Accordi, Benedetta; Basso, Giuseppe; Gaspar, John Antonydas; Zagoura, Dimitra; Barilari, Manuela; Palosaari, Taina; Sachinidis, Agapios; Bremer-Hoffmann, Susanne

    2014-10-15

    According to the advocated paradigm shift in toxicology, acquisition of knowledge on the mechanisms underlying the toxicity of chemicals, such as perturbations of biological pathways, is of primary interest. Pluripotent stem cells (PSCs), such as human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), offer a unique opportunity to derive physiologically relevant human cell types to measure molecular and cellular effects of such pathway modulations. Here we compared the neuronal differentiation propensity of hESCs and hiPSCs with the aim to develop novel hiPSC-based tools for measuring pathway perturbation in relation to molecular and cellular effects in vitro. Among other fundamental pathways, also, the cAMP responsive element binding protein (CREB) pathway was activated in our neuronal models and gave us the opportunity to study time-dependent effects elicited by chemical perturbations of the CREB pathway in relation to cellular effects. We show that the inhibition of the CREB pathway, using 2-naphthol-AS-E-phosphate (KG-501), induced an inhibition of neurite outgrowth and synaptogenesis, as well as a decrease of MAP2{sup +} neuronal cells. These data indicate that a CREB pathway inhibition can be related to molecular and cellular effects that may be relevant for neurotoxicity testing, and, thus, qualify the use of our hiPSC-derived neuronal model for studying chemical-induced neurotoxicity resulting from pathway perturbations. - Highlights: • HESCs derived neuronal cells serve as benchmark for iPSC based neuronal toxicity test development. • Comparisons between hESCs and hiPSCs demonstrated variability of the epigenetic state • CREB pathway modulation have been explored in relation to the neurotoxicant exposure KG-501 • hiPSC might be promising tools to translate theoretical AoPs into toxicological in vitro tests.

  10. Comparison between bioconcentration factor (BCF) data provided by industry to the European Chemicals Agency (ECHA) and data derived from QSAR models.

    PubMed

    Petoumenou, Maria I; Pizzo, Fabiola; Cester, Josep; Fernández, Alberto; Benfenati, Emilio

    2015-10-01

    The bioconcentration factor (BCF) is the ratio of the concentration of a chemical in an organism to the concentration in the surrounding environment at steady state. It is a valuable indicator of the bioaccumulation potential of a substance. BCF is an essential environmental property required for regulatory purposes within the Registration, Evaluation, Authorization and restriction of Chemicals (REACH) and Globally Harmonized System (GHS) regulations. In silico models for predicting BCF can facilitate the risk assessment for aquatic toxicology and reduce the cost and number of animals used. The aim of the present study was to examine the correlation of BCF data derived from the dossiers of registered chemicals submitted to the European Chemical Agency (ECHA) with the results of a battery of Quantitative Structure-Activity Relationship (QSAR). After data pruning, statistical analysis was performed using the predictions of the selected models. Results in terms of R(2) had low rating around 0.5 for the pruned dataset. The use of the model applicability domain index (ADI) led to an improvement of the performance for compounds falling within it. The variability of the experimental data and the use of different parameters to define the applicability domain can influence the performance of each model. All available information should be adapted to the requirements of the regulation to obtain a safe decision. PMID:26282223

  11. Chemical insight from density functional modeling of molecular adsorption: Tracking the bonding and diffusion of anthracene derivatives on Cu(111) with molecular orbitals

    SciTech Connect

    Wyrick, Jonathan; Bartels, Ludwig; Einstein, T. L.

    2015-03-14

    We present a method of analyzing the results of density functional modeling of molecular adsorption in terms of an analogue of molecular orbitals. This approach permits intuitive chemical insight into the adsorption process. Applied to a set of anthracene derivates (anthracene, 9,10-anthraquinone, 9,10-dithioanthracene, and 9,10-diselenonanthracene), we follow the electronic states of the molecules that are involved in the bonding process and correlate them to both the molecular adsorption geometry and the species’ diffusive behavior. We additionally provide computational code to easily repeat this analysis on any system.

  12. Chemical insight from density functional modeling of molecular adsorption: Tracking the bonding and diffusion of anthracene derivatives on Cu(111) with molecular orbitals.

    PubMed

    Wyrick, Jonathan; Einstein, T L; Bartels, Ludwig

    2015-03-14

    We present a method of analyzing the results of density functional modeling of molecular adsorption in terms of an analogue of molecular orbitals. This approach permits intuitive chemical insight into the adsorption process. Applied to a set of anthracene derivates (anthracene, 9,10-anthraquinone, 9,10-dithioanthracene, and 9,10-diselenonanthracene), we follow the electronic states of the molecules that are involved in the bonding process and correlate them to both the molecular adsorption geometry and the species' diffusive behavior. We additionally provide computational code to easily repeat this analysis on any system. PMID:25770496

  13. Spontaneous assembly of silylethane-thiol derivatives on Au(111): a chemically robust thiol protecting group as the precursor for the direct formation of aromatic gold thiolate monolayers.

    PubMed

    Niebel, Claude; Calard, Franois; Jarrosson, Thibaut; Lre-Porte, Jean-Pierre; Breton, Tony; Serein-Spirau, Franoise

    2015-05-01

    Self-assembled monolayers (SAMs) on gold were obtained by the direct absorption of a fully conjugated phenylenethienylene derivative () presenting robust silylethane-thiol protecting groups as anchoring agents. The thiol deprotection and SAM formation have been evidenced by quartz crystal microbalance (QCM) measurements and X-ray photoelectron spectroscopy (XPS), and have been compared to the SAM obtained from its thioacetate analog (5). The chemically robust silylethane-thiol protecting group appeared as a surprisingly effective anchoring agent for the preparation of aromatic SAMs on Au(111), suitable for subsequent post-functionalization. PMID:25848655

  14. Chemical insight from density functional modeling of molecular adsorption: Tracking the bonding and diffusion of anthracene derivatives on Cu(111) with molecular orbitals

    NASA Astrophysics Data System (ADS)

    Wyrick, Jonathan; Einstein, T. L.; Bartels, Ludwig

    2015-03-01

    We present a method of analyzing the results of density functional modeling of molecular adsorption in terms of an analogue of molecular orbitals. This approach permits intuitive chemical insight into the adsorption process. Applied to a set of anthracene derivates (anthracene, 9,10-anthraquinone, 9,10-dithioanthracene, and 9,10-diselenonanthracene), we follow the electronic states of the molecules that are involved in the bonding process and correlate them to both the molecular adsorption geometry and the species' diffusive behavior. We additionally provide computational code to easily repeat this analysis on any system.

  15. The Redox Chemistry and Chemical Biology of H2S, Hydropersulfides and Derived Species: Implications to Their Possible Biological Activity and Utility

    PubMed Central

    Ono, Katsuhiko; Akaike, Takaake; Sawa, Tomohiro; Kumagai, Yoshito; Wink, David A.; Tantillo, Dean J.; Hobbs, Adrian J.; Nagy, Peter; Xian, Ming; Lin, Joseph; Fukuto, Jon M.

    2014-01-01

    Hydrogen sulfide (H2S) is an endogenously generated and putative signaling/effector molecule. In spite of its numerous reported functions, the chemistry by which it elicits its functions is not understood. Moreover, recent studies allude to the existence of other sulfur species besides H2S that may play critical physiological roles. Herein, the basic chemical biology of H2S as well as other related or derived species is discussed and reviewed. A particular focus of this review are the per- and poly-sulfides which are likely in equilibrium with free H2S and which may be important biological effectors themselves. PMID:25229186

  16. Biotechnology of flavonoids and other phenylpropanoid-derived natural products. Part I: Chemical diversity, impacts on plant biology and human health.

    PubMed

    Ververidis, Filippos; Trantas, Emmanouil; Douglas, Carl; Vollmer, Guenter; Kretzschmar, Georg; Panopoulos, Nickolas

    2007-10-01

    Plant natural products derived from phenylalanine and the phenylpropanoid pathway are impressive in their chemical diversity and are the result of plant evolution, which has selected for the acquisition of large repertoires of pigments, structural and defensive compounds, all derived from a phenylpropanoid backbone via the plant-specific phenylpropanoid pathway. These compounds are important in plant growth, development and responses to environmental stresses and thus can have large impacts on agricultural productivity. While plant-based medicines containing phenylpropanoid-derived active components have long been used by humans, the benefits of specific flavonoids and other phenylpropanoid-derived compounds to human health and their potential for long-term health benefits have been only recognized more recently. In this part of the review, we discuss the diversity and biosynthetic origins of phenylpropanoids and particularly of the flavonoid and stilbenoid natural products. We then review data pertaining to the modes of action and biological properties of these compounds, referring on their effects on human health and physiology and their roles as plant defense and antimicrobial compounds. This review continues in Part II discussing the use of biotechnological tools targeting the rational reconstruction of multienzyme pathways in order to modify the production of such compounds in plants and model microbial systems for the benefit of agriculture and forestry. PMID:17935117

  17. Biogenic Synthesis, Purification, and Chemical Characterization of Anti-inflammatory Resolvins Derived from Docosapentaenoic Acid (DPAn-6)

    PubMed Central

    Dangi, Bindi; Obeng, Marcus; Nauroth, Julie M.; Teymourlouei, Mah; Needham, Micah; Raman, Krishna; Arterburn, Linda M.

    2009-01-01

    Enzymatically oxygenated derivatives of the ω-3 fatty acids cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) and cis-5,8,11,14,17-eicosapentaenoic acid, known as resolvins, have potent inflammation resolution activity (Serhan, C. N., Clish, C. B., Brannon, J., Colgan, S. P., Chiang, N., and Gronert, K. (2000) J. Exp. Med. 192, 1197–1204; Hong, S., Gronert, K., Devchand, P. R., Moussignac, R., and Serhan, C. N. (2003) J. Biol. Chem. 278, 14677–14687). Our objective was to determine whether similar derivatives are enzymatically synthesized from other C-22 fatty acids and whether these molecules possess inflammation resolution properties. The reaction of DHA, DPAn-3, and DPAn-6 with 5-, 12-, and 15-lipoxygenases produced oxylipins, which were identified and characterized by liquid chromatography coupled with tandem mass-spectrometry. DPAn-6 and DPAn-3 proved to be good substrates for 15-lipoxygenase. 15-Lipoxygenase proved to be the most efficient enzyme of the three tested for conversion of long chain polyunsaturated fatty acids to corresponding oxylipins. Since DPAn-6 is a major component of Martek DHA-S™ oil, we focused our attention on reaction products obtained from the DPAn-6 and 15-lipoxygenase reaction. (17S)-hydroxy-DPAn-6 and (10,17S)-dihydroxy-DPAn-6 were the main products of this reaction. These compounds were purified by preparatory high performance liquid chromatography techniques and further characterized by NMR, UV spectrophotometry, and tandem mass spectrometry. We tested both compounds in two animal models of acute inflammation and demonstrated that both compounds are potent anti-inflammatory agents that are active on local intravenous as well as oral administration. These oxygenated DPAn-6 compounds can thus be categorized as a new class of DPAn-6-derived resolvins. PMID:19324874

  18. Human Induced Pluripotent Stem Cell Derived Neuronal Cells Cultured on Chemically-Defined Hydrogels for Sensitive In Vitro Detection of Botulinum Neurotoxin.

    PubMed

    Pellett, Sabine; Schwartz, Michael P; Tepp, William H; Josephson, Richard; Scherf, Jacob M; Pier, Christina L; Thomson, James A; Murphy, William L; Johnson, Eric A

    2015-01-01

    Botulinum neurotoxin (BoNT) detection provides a useful model for validating cell-based neurotoxicity screening approaches, as sensitivity is dependent on functionally competent neurons and clear quantitative endpoints are available for correlating results to approved animal testing protocols. Here, human induced pluripotent stem cell (iPSC)-derived neuronal cells were cultured on chemically-defined poly(ethylene glycol) (PEG) hydrogels formed by "thiol-ene" photopolymerization and tested as a cell-based neurotoxicity assay by determining sensitivity to active BoNT/A1. BoNT/A1 sensitivity was comparable to the approved in vivo mouse bioassay for human iPSC-derived neurons and neural stem cells (iPSC-NSCs) cultured on PEG hydrogels or treated tissue culture polystyrene (TCP) surfaces. However, maximum sensitivity for BoNT detection was achieved two weeks earlier for iPSC-NSCs that were differentiated and matured on PEG hydrogels compared to TCP. Therefore, chemically-defined synthetic hydrogels offer benefits over standard platforms when optimizing culture conditions for cell-based screening and achieve sensitivities comparable to an approved animal testing protocol. PMID:26411797

  19. Human Induced Pluripotent Stem Cell Derived Neuronal Cells Cultured on Chemically-Defined Hydrogels for Sensitive In Vitro Detection of Botulinum Neurotoxin

    PubMed Central

    Pellett, Sabine; Schwartz, Michael P.; Tepp, William H.; Josephson, Richard; Scherf, Jacob M.; Pier, Christina L.; Thomson, James A.; Murphy, William L.; Johnson, Eric A.

    2015-01-01

    Botulinum neurotoxin (BoNT) detection provides a useful model for validating cell-based neurotoxicity screening approaches, as sensitivity is dependent on functionally competent neurons and clear quantitative endpoints are available for correlating results to approved animal testing protocols. Here, human induced pluripotent stem cell (iPSC)-derived neuronal cells were cultured on chemically-defined poly(ethylene glycol) (PEG) hydrogels formed by thiol-ene photopolymerization and tested as a cell-based neurotoxicity assay by determining sensitivity to active BoNT/A1. BoNT/A1 sensitivity was comparable to the approved in vivo mouse bioassay for human iPSC-derived neurons and neural stem cells (iPSC-NSCs) cultured on PEG hydrogels or treated tissue culture polystyrene (TCP) surfaces. However, maximum sensitivity for BoNT detection was achieved two weeks earlier for iPSC-NSCs that were differentiated and matured on PEG hydrogels compared to TCP. Therefore, chemically-defined synthetic hydrogels offer benefits over standard platforms when optimizing culture conditions for cell-based screening and achieve sensitivities comparable to an approved animal testing protocol. PMID:26411797

  20. Effect of ethylene glycol on the orientation and magnetic properties of barium ferrite thin films derived by chemical solution deposition

    NASA Astrophysics Data System (ADS)

    Meng, Siqin; Yue, Zhenxing; Li, Longtu

    2014-03-01

    M-type barium ferrite (BaM) film is a promising candidate for magnetic recording media and the next-generation high-frequency microwave material. BaM films were fabricated using a chemical solution spin-coating deposition method on (001) plane sapphire. The effect of ethylene glycol (EG) on precursor solution and annealing temperature on microstructure and magnetic properties were investigated. X-ray diffraction showed that strong out-of-plane (001) texture in BaM films can be achieved with adequate EG addition. Films fabricated without EG addition or annealed at lower temperatures showed partial hematite secondary phase. The epitaxial formation of hematite secondary phase on sapphire substrate was confirmed by the X-ray diffraction ?-scan technique. Magnetic measurements showed out-of-plane anisotropy in BaM films. The crystallographic texture and magnetic anisotropy of the films are related to the film microstructure.

  1. The effects of activation temperature on physico-chemical characteristics of activated carbons derived from biomass wastes

    NASA Astrophysics Data System (ADS)

    Sutrisno, Bachrun; Hidayat, Arif

    2015-12-01

    This research focused on investigating in the effect of activation temperature on the physico-chemical properties of palm empty fruit bunch (PEFB) based activated carbon prepared by physical activation with carbon dioxide. The activation temperature was studied in the range of 400-800°C by keeping the activation temperature at 800°C for 120 min. It was found that the porous properties of activated carbon decreased with an increase in carbonization temperature. The activated carbons prepared at the highest activation temperature at 800°C and activation time of 120 min gave the activated carbon with the highest of BET surface area and pore volume of 938 m2/g and 0.4502 cm3/g, respectively

  2. Coumarins from the Herb Cnidium monnieri and chemically modified derivatives as antifoulants against Balanus albicostatus and Bugula neritina larvae.

    PubMed

    Wang, Zhan-Chang; Feng, Dan-Qing; Ke, Cai-Huan

    2013-01-01

    In the search for new environmental friendly antifouling (AF) agents, four coumarins were isolated from the herbal plant Cnidium monnieri, known as osthole (1), imperatorin (2), isopimpinellin (3) and auraptenol (4). Furthermore, five coumarin derivatives, namely 8-epoxypentylcoumarin (5), meranzin hydrate (6), 2'-deoxymetranzin hydrate (7), 8-methylbutenalcoumarin (8), and micromarin-F (9) were synthesized from osthole. Compounds 1, 2, 4, 7 showed high inhibitory activities against larval settlement of Balanus albicostatus with EC(50) values of 4.64, 3.39, 3.38, 4.67 μg mL-1. Compound 8 could significantly inhibit larval settlement of Bugula neritina with an EC(50) value of 3.87 μg mL-1. The impact of functional groups on anti-larval settlement activities suggested that the groups on C-5' and C-2'/C-3' of isoamylene chian could affect the AF activities. PMID:23303279

  3. Coumarins from the Herb Cnidium monnieri and Chemically Modified Derivatives as Antifoulants against Balanus albicostatus and Bugula neritina Larvae

    PubMed Central

    Wang, Zhan-Chang; Feng, Dan-Qing; Ke, Cai-Huan

    2013-01-01

    In the search for new environmental friendly antifouling (AF) agents, four coumarins were isolated from the herbal plant Cnidium monnieri, known as osthole (1), imperatorin (2), isopimpinellin (3) and auraptenol (4). Furthermore, five coumarin derivatives, namely 8-epoxypentylcoumarin (5), meranzin hydrate (6), 2′-deoxymetranzin hydrate (7), 8-methylbutenalcoumarin (8), and micromarin-F (9) were synthesized from osthole. Compounds 1, 2, 4, 7 showed high inhibitory activities against larval settlement of Balanus albicostatus with EC50 values of 4.64, 3.39, 3.38, 4.67 μg mL−1. Compound 8 could significantly inhibit larval settlement of Bugula neritina with an EC50 value of 3.87 μg mL−1. The impact of functional groups on anti-larval settlement activities suggested that the groups on C-5′ and C-2′/C-3′ of isoamylene chian could affect the AF activities. PMID:23303279

  4. Chemical modification of silica gel with synthesized new Schiff base derivatives and sorption studies of cobalt (II) and nickel (II)

    NASA Astrophysics Data System (ADS)

    Kursunlu, Ahmed Nuri; Guler, Ersin; Dumrul, Hakan; Kocyigit, Ozcan; Gubbuk, Ilkay Hilal

    2009-08-01

    In this study, three Schiff base ligands and their complexes were synthesized and characterized by infrared spectroscopy (IR), thermogravimetric analyses (TGA), nuclear magnetic resonance (NMR), elemental analysis and magnetic susceptibility apparatuses. Silica gel was respectively modified with Schiff base derivatives, (E)-2-[(2-chloroethylimino)methyl]phenol, (E)-4-[(2-chloroethylimino)methyl]phenol and N, N'-[1,4-phenilendi(E)methylidene]bis(2-chloroethanamine), after silanization of silica gel by (3-aminopropyl)trimethoxysilane (APTS) by using a suitable method. Characterization of the surface modification was also performed with IR, TGA and elemental analysis. The immobilized surfaces were used for Co(II) and Ni(II) sorption from aqueous solutions and values of sorption were detected by atomic absorption spectrometer (AAS).

  5. Chemical Conjugation of Evans Blue Derivative: A Strategy to Develop Long-Acting Therapeutics through Albumin Binding

    PubMed Central

    Chen, Haojun; Wang, Guohao; Lang, Lixin; Jacobson, Orit; Kiesewetter, Dale O.; Liu, Yi; Ma, Ying; Zhang, Xianzhong; Wu, Hua; Zhu, Lei; Niu, Gang; Chen, Xiaoyuan

    2016-01-01

    The efficacy of therapeutic drugs is highly dependent on their optimal in vivo pharmacokinetics. Albumin conjugation is considered to be one of the most effective means of protracting the short lifespan of peptides and proteins. In this study, we proposed a novel platform for developing long lasting therapeutics by conjugating a small molecular albumin binding moiety, truncated Evans blue, to either peptides or proteins. Using the anti-diabetic peptide drug Exendin-4 as a model peptide, we synthesized a new long-acting Exendin-4 derivative (denoted as Abextide). Through complexation with albumin in situ, the biological half-life of Abextide was significantly extended. The hypoglycemic effect of Abextide was also improved remarkably over Exendin-4. Thus, Abextide has considerable potential to treat type 2 diabetes. This strategy as a general technology platform can be applied to other small molecules and biologics for the development of long-acting therapeutic drugs. PMID:26877782

  6. Chemical interaction of atmospheric mineral dust-derived nanoparticles with natural seawater--EPS and sunlight-mediated changes.

    PubMed

    Kadar, Enik; Cunliffe, Michael; Fisher, Andrew; Stolpe, Bjrn; Lead, Jamie; Shi, Zongbo

    2014-01-15

    Laboratory studies were conducted to investigate the interactions of nanoparticles (NPs) formed via simulated cloud processing of mineral dust with seawater under environmentally relevant conditions. The effect of sunlight and the presence of exopolymeric substances (EPS) were assessed on the: (1) colloidal stability of the nanoparticle aggregates (i.e. size distribution, zeta potential, polydispersity); (2) micromorphology and (3) Fe dissolution from particles. We have demonstrated that: (i) synthetic nano-ferrihydrite has distinct aggregation behaviour from NPs formed from mineral dusts in that the average hydrodynamic diameter remained unaltered upon dispersion in seawater (~1500 nm), whilst all dust derived NPs increased about three fold in aggregate size; (ii) relatively stable and monodisperse aggregates of NPs formed during simulated cloud processing of mineral dust become more polydisperse and unstable in contact with seawater; (iii) EPS forms stable aggregates with both the ferrihydrite and the dust derived NPs whose hydrodynamic diameter remains unchanged in seawater over 24h; (iv) dissolved Fe concentration from NPs, measured here as <3 kDa filter-fraction, is consistently >30% higher in seawater in the presence of EPS and the effect is even more pronounced in the absence of light; (v) micromorphology of nanoparticles from mineral dusts closely resemble that of synthetic ferrihydrite in MQ water, but in seawater with EPS they form less compact aggregates, highly variable in size, possibly due to EPS-mediated steric and electrostatic interactions. The larger scale implications on real systems of the EPS solubilising effect on Fe and other metals with the additional enhancement of colloidal stability of the resulting aggregates are discussed. PMID:24035844

  7. Optical Fiber Chemical Sensor with Sol-Gel Derived Refractive Material as Transducer for High Temperature Gas Sensing in Clean Coal Technology

    SciTech Connect

    Shiquan Tao

    2006-12-31

    The chemistry of sol-gel derived silica and refractive metal oxide has been systematically studied. Sol-gel processes have been developed for preparing porous silica and semiconductor metal oxide materials. Micelle/reversed micelle techniques have been developed for preparing nanometer sized semiconductor metal oxides and noble metal particles. Techniques for doping metal ions, metal oxides and nanosized metal particles into porous sol-gel material have also been developed. Optical properties of sol-gel derived materials in ambient and high temperature gases have been studied by using fiber optic spectroscopic techniques, such as fiber optic ultraviolet/visible absorption spectrometry, fiber optic near infrared absorption spectrometry and fiber optic fluorescence spectrometry. Fiber optic spectrometric techniques have been developed for investigating the optical properties of these sol-gel derived materials prepared as porous optical fibers or as coatings on the surface of silica optical fibers. Optical and electron microscopic techniques have been used to observe the microstructure, such as pore size, pore shape, sensing agent distribution, of sol-gel derived material, as well as the size and morphology of nanometer metal particle doped in sol-gel derived porous silica, the nature of coating of sol-gel derived materials on silica optical fiber surface. In addition, the chemical reactions of metal ion, nanostructured semiconductor metal oxides and nanometer sized metal particles with gas components at room temperature and high temperatures have also been investigated with fiber optic spectrometric methods. Three classes of fiber optic sensors have been developed based on the thorough investigation of sol-gel chemistry and sol-gel derived materials. The first group of fiber optic sensors uses porous silica optical fibers doped with metal ions or metal oxide as transducers for sensing trace NH{sub 3} and H{sub 2}S in high temperature gas samples. The second group of fiber optic sensors uses sol-gel derived porous silica materials doped with nanometer particles of noble metals in the form of fiber or coating for sensing trace H{sub 2}, NH{sub 3} and HCl in gas samples at for applications ambient temperature. The third classes of fiber optic sensors use sol-gel derived semiconductor metal oxide coating on the surface of silica optical fiber as transducers for selectively sensing H{sub 2}, CH{sub 4} and CO at high temperature. In addition, optical fiber temperature sensors use the fluorescence signal of rare-earth metal ions doped porous silica optical fiber or the optical absorption signal of thermochromic metal oxide materials coated on the surface of silica optical fibers have also been developed for monitoring gas temperature of corrosive gas. Based on the results obtained from this project, the principle of fiber optic sensor techniques for monitoring matrix gas components as well as trace components of coal gasification derived syngas has been established. Prototype sensors for sensing trace ammonia and hydrogen sulfide in gasification derived syngas have been built up in our laboratory and have been tested using gas samples with matrix gas composition similar to that of gasification derived fuel gas. Test results illustrated the feasibility of these sensors for applications in IGCC processes.

  8. Composite bound states and broken U(1) symmetry in the chemical-master-equation derivation of the Gray-Scott model.

    PubMed

    Cooper, Fred; Ghoshal, Gourab; Prez-Mercader, Juan

    2013-10-01

    We give a first principles derivation of the stochastic partial differential equations that describe the chemical reactions of the Gray-Scott model (GS): U+2V ?[?]3V and V ? [?]P, U ? [?]Q, with a constant feed rate for U. We find that the conservation of probability ensured by the chemical master equation leads to a modification of the usual differential equations for the GS model, which now involves two composite fields and also intrinsic noise terms. One of the composites is ?(1) = ?(v)(2), where {?(v)}(?) =v is the concentration of the species V and the averaging is over the internal noise ?(u,v,?(1)). The second composite field is the product of three fields ? = ??(u)?(v)(2) and requires a noise source to ensure probability conservation. A third composite ?(2) = ?(u)?(v) can also be identified from the noise-induced reactions. The Hamiltonian that governs the time evolution of the many-body wave function, associated with the master equation, has a broken U(1) symmetry related to particle number conservation. By expanding around the (broken symmetry) zero-energy solution of the Hamiltonian (by performing a Doi shift) one obtains from our path integral formulation the usual reaction diffusion equation, at the classical level. The Langevin equations that are derived from the chemical master equation have multiplicative noise sources for the density fields ?(u), ?(v),? that induce higher-order processes such as n ? n scattering for n>3. The amplitude of the noise acting on ?(v) is itself stochastic in nature. PMID:24229268

  9. Predicted no effect concentration derivation as a significant source of variability in environmental hazard assessments of chemicals in aquatic systems: an international analysis.

    PubMed

    Hahn, Thorsten; Diamond, Jerry; Dobson, Stuart; Howe, Paul; Kielhorn, Janet; Koennecker, Gustav; Lee-Steere, Chris; Mangelsdorf, Inge; Schneider, Uwe; Sugaya, Yoshio; Taylor, Ken; Dam, Rick Van; Stauber, Jenny L

    2014-01-01

    Environmental hazard assessments for chemicals are carried out to define an environmentally "safe" level at which, theoretically, the chemical will not negatively affect any exposed biota. Despite this common goal, the methodologies in use are very diverse across different countries and jurisdictions. This becomes particularly obvious when international scientists work together on documents with global scope, e.g., in the World Health Organization (WHO) International Program on Chemical Safety. In this article, we present a study that describes the extent of such variability and analyze the reasons that lead to different outcomes in deriving a "safe level" (termed the predicted no effect concentration [PNEC] throughout this article). For this purpose, we chose 5 chemicals to represent well-known substances for which sufficient high-quality aquatic effects data were available: ethylene glycol, trichloroethylene, nonylphenol, hexachlorobenzene, and copper (Cu). From these data, 2 data sets for each chemical were compiled: the full data set, that contained all information from selected peer-review sources, and the base data set, a subsample of the full set simulating limited data. Scientists from the European Union (EU), United States, Canada, Japan, and Australia independently carried out hazard assessments for each of these chemicals using the same data sets. Their reasoning for key study selection, use of assessment factors, or use of probabilistic methods was comprehensively documented. The observed variation in the PNECs for all chemicals was up to 3 orders of magnitude, and this was not simply due to obvious factors such as the size of the data set or the methodology used. Rather, this was due to individual decisions of the assessors within the scope of the methodology used, especially key study selection, acute versus chronic definitions, and size of assessment factors. Awareness of these factors, together with transparency of the decision-making process, would be necessary to minimize confusion and uncertainty related to different hazard assessment outcomes, particularly in international documents. The development of a "guideline on transparency in decision-making" ensuring the decision-making process is science-based, understandable, and transparent, may therefore be a promising way forward. PMID:23913910

  10. Derived no-effect levels (DNELs) under the European chemicals regulation REACH--an analysis of long-term inhalation worker-DNELs presented by industry.

    PubMed

    Schenk, Linda; Deng, Uriell; Johanson, Gunnar

    2015-05-01

    The European REACH regulation places responsibility for providing safety information, including derived no-effect levels (DNELs), on chemicals and chemical products on 'industry', i.e. manufacturers and importers. We compared long-term inhalation worker-DNELs (wDNELs) presented by industry with the corresponding Swedish occupational exposure limits (OELs), and for a subset, with wDNELs derived by us. Our wDNELs were derived using toxicological evaluations published by the Swedish Criteria Group and our interpretation of the REACH Guidance. On average, industry's wDNELs were the same as the Swedish OELs (median of wDNEL-OEL ratios: 0.98, n = 235). However, the variation was huge, the extremes being up to 450 times higher, and up to 230 times lower than the corresponding OEL. Nearly one-fifth of the wDNELs were ?2 times higher and one-third ?2 times lower than the OEL. No time trend was seen in the wDNEL/OEL ratios, suggesting that older OELs were not systematically higher than the more recent ones. Industry's wDNELs varied widely and were generally higher (median 4.2 times, up to 435 times higher, down to 13 times lower, n = 23) also compared to our wDNELs. Only five industry wDNELs were equal to or lower than ours. The choices of key studies, dose descriptors, and assessment factors all seemed to contribute to the discrepancies. We conclude that although the REACH guidance is detailed, many choices that will influence the wDNEL lack firm instructions. A major problem is that little advice is given on when and how to depart from default assessment factors. PMID:25471229

  11. Improved activity and stability of alkaline phosphatases from psychrophilic and mesophilic organisms by chemically modifying aliphatic or amino groups using tetracarboxy-benzophenone derivatives.

    PubMed

    Siddiqui, K S; Poljak, A; Cavicchioli, R

    2004-07-01

    The activity-stability-structure relationship of the cold-active alkaline phosphatase from Red Arctic shrimp, Pandalus borealis (SAP) was studied by chemically modifying aliphatic (C-H) or amino (NH2) groups using benzophenone tetracarboxylic derivatives in either a light (UV-A) or dark reaction. The response of the cold-adapted enzyme was compared to a similarly modified calf alkaline phosphatase (CAP). MALDI-TOF-MS was used to determine the extent and nature of the modifications in both SAP and CAP. On average 2 to 4 amino acid residues were linked to a BP-modifier, with up to 18 to 21 amino acids modified in a smaller portion of the material. The effect of the modifications on kinetic and thermodynamic properties varied with the enzyme and type of modification. The aliphatic-group modified SAP demonstrated typical characteristics of a mesophilic enzyme, consistent with an activity-stability trade-off where gain in thermostability was attained at the expense of decreased activity. In contrast, the activity of the amino-group modified SAP attained an even more psychrophilic character with respect to its kinetic (increase in kcat and Km) and thermodynamic (reduction in deltaH#) properties. Interestingly, the amino-group modified SAP also acquired higher thermostability, thus demonstrating that both activity and stability can be simultaneously enhanced using chemical modification. The study demonstrates the applicability of benzophenone chemical modification for improving the thermal properties of enzymes from psychrophiles and mesophiles. PMID:15559981

  12. Quantum-chemical calculations of the electronic structure of 2-amino-1,3-dicyano-5,6,7,8-tetrahydronaphthalene derivatives.

    PubMed

    Jzefowicz, M; Bajorek, A; Pietrzak, M; Heldt, J R

    2013-09-01

    The UV-Visible absorption spectra of six, newly synthesized donor-substituted 2-amino-1,3-dicyano-5,6,7,8-tetrahydronaphthalene have been measured in methylcyclohexane (MCH) and assigned with the help of quantum-chemical calculations. Our calculations have been performed to assess information regarding the electronic state energy values, corresponding oscillator strengths, x-, y-, z-components of the transition dipole moments and molecular orbitals involved in the main electronic transitions of the studied compounds. Additionally, the experimental absorption transition dipole moments were calculated, on the basis of spectroscopic data, and compared with results of our quantum-chemical calculations. On the basis of the experimental results and quantum-chemical calculations, it was shown that the long-wavelength absorption band involves an overlap of three electronic transitions of different character. For all studied donor-acceptor (D-A) compounds in vapour-phase, the long-wavelength transition (S0?S1) does not possess charge transfer character, whereas the S0?S2 transition possesses electron transfer character e.g., ?-electrons of the acceptor moiety are moved to the donor part. Moreover, it is found that the electronic structure of the studied biphenyl derivatives can be approximately described within composite-model of decoupled moieties: donor and acceptor. PMID:23719413

  13. UV-vis spectroscopy and semiempirical quantum chemical studies on methyl derivatives of annulated analogues of azafluoranthene and azulene dyes

    NASA Astrophysics Data System (ADS)

    Danel, K. S.; G?siorski, P.; Matusiewicz, M.; Ca?us, S.; Uchacz, T.; Kityk, A. V.

    2010-09-01

    Paper reports the measured optical absorption and fluorescence spectra of 4-(2-chlorophenyl)-7-methyl-1,3-diphenyl-1 H-pyrazolo[3,4-b]quinoline (MCPDPPQ), as well as 6-methyl-1,3-diphenyl-3 H-indeno[1,2,3- de]pyrazolo[3,4- b]quinoline (MDPIPQ) and 9-methyl-6-phenyl-6 H-5,6,7-triazadibenzo[ f,h]naphtho[3,2,1- cd]azulene (MPTNA) representing cyclized five- or seven-membered regioisomeric products of MCPDPPQ, respectively. The spectra has been recorded in solvents of different polarity and compared with the results of quantum chemical calculations performed by means of the semiempirical method PM3 in combination with molecular dynamics (MD) simulations. Cyclization of MCPDPPQ into MDPIPQ or MPTNA is accompanied by a significant red shift of the first optical absorption and fluorescence bands. While the solvent polarity rises all the dyes exhibit the blue shift of the first absorption band and the red shift of the fluorescence band. These trends have been reproduced within the semiempirical calculations in combination with the Lippert-Mataga dielectric polarization model and explained by specific orientations of the dipole moments in the ground and excited states. All dyes may be considered as candidates for the luminescent or electroluminescent applications. Depending on solvent polarity they emit light in the green-yellow range of the visible spectra.

  14. Optical absorption measurements and quantum-chemical simulations of optical properties of novel fluoro derivatives of pyrazoloquinoline

    NASA Astrophysics Data System (ADS)

    Brik, M. G.; Kuznik, W.; Gondek, E.; Kityk, I. V.; Uchacz, T.; Szlachcic, P.; Jarosz, B.; Plucinski, K. J.

    2010-05-01

    The results of experimental research and quantum-chemical simulations of the absorption spectra of 1-(4-fluorophenyl)-3,4-diphenyl, 3-(4-fluorophenyl)-1,4-diphenyl, and 4-(4-fluorophenyl)-1,3-diphenyl-pyrazolo[3,4- b] quinoline are presented. Although the fluorine atom is located on different phenyl rings in these molecules, the absorption spectra do not differ significantly. Semi-empirical AM1, PM3 and RM1 methods, as well as ab initio ADF code-based calculations were used to optimize geometry, calculate the infrared and visible spectra of the afore mentioned compounds and analyze the molecular orbitals schemes. The results of calculations are in good agreement with the experimental data. It was also demonstrated that the positions of the fluorescence maxima depend significantly on the solvent (contrary to the absorption spectra), in which the molecules are embedded, which allows for manipulating with fluorescence properties of the synthesized molecules by changing the solvent.

  15. Effects of lithium doping on microstructure, electrical properties, and chemical bonds of sol-gel derived NKN thin films

    SciTech Connect

    Lin, Chun-Cheng; Chen, Chan-Ching; Weng, Chung-Ming; Chu, Sheng-Yuan; Tsai, Cheng-Che

    2015-02-28

    Highly (100/110) oriented lead-free Li{sub x}(Na{sub 0.5}K{sub 0.5}){sub 1−x}NbO{sub 3} (LNKN, x = 0, 0.02, 0.04, and 0.06) thin films are fabricated on Pt/Ti/SiO{sub 2}/Si substrates via a sol-gel processing method. The lithium (Li) dopants modify the microstructure and chemical bonds of the LNKN films, and therefore improve their electrical properties. The optimal values of the remnant polarization (P{sub r} = 14.3 μC/cm{sup 2}), piezoelectric coefficient (d{sub 33} = 48.1 pm/V), and leakage current (<10{sup −5} A/cm{sup 2}) are obtained for a lithium addition of x = 0.04 (i.e., 4 at. %). The observation results suggest that the superior electrical properties are the result of an improved crystallization, a larger grain size, and a smoother surface morphology. It is shown that the ion transport mechanism is dominated by an Ohmic behavior under low electric fields and the Poole-Frenkel emission effect under high electric fields.

  16. An ionic liquid tolerant cellulase derived from chemically polluted microhabitats and its application in in situ saccharification of rice straw.

    PubMed

    Xu, Jiaxing; He, Bingfang; Wu, Bin; Wang, Bin; Wang, Chenghua; Hu, Lei

    2014-04-01

    A cellulase-producing fungus was isolated from chemically polluted microhabitats by [Amim][Cl] enrichment and identified as Aspergillus fumigatus. The maximum activity of the cellulase in 30% (v/v) ionic liquids (ILs) was detected in [Emim][DMP], [Amim][Cl] and [Emim][MA] as 127%, 111% and 109%, respectively, of its activity in buffer, suggesting its superior performance in high concentration ILs. Strikingly, although its initial activity varied in each IL, its half-life was longer in most ILs than in buffer, evidence of a high conformational stability of the enzyme that is essential for maintaining the remaining activity in relevant media. It noteworthy that 1-3M NaCl can activate the cellulase somewhat. More gratifyingly, a compatible IL-cellulase system based on the cellulase was developed, and its use significantly improved the saccharification rate of rice straw from 53% to 88% versus the control, demonstrating its potential for efficient transformation of lignocellulose to glucose in a single-step process. PMID:24549238

  17. Chemical characteristics and enhanced hepatoprotective activities of Maillard reaction products derived from milk protein-sugar system.

    PubMed

    Oh, Nam Su; Young Lee, Ji; Lee, Hyun Ah; Joung, Jae Yeon; Shin, Yong Kook; Kim, Sae Hun; Kim, Younghoon; Lee, Kwang Won

    2016-02-01

    The objective of this study was to investigate the characteristics, antioxidative properties, and hepatoprotective effects of Maillard reaction products (MRP) from milk protein reacted with sugars. The MRP were obtained from milk protein, whey protein concentrates and sodium caseinate, using 2 types of sugars, lactose and glucose, by heating the mixture at 55C for 7d in a sodium phosphate buffer (pH 7.4). Changes in the chemical modification of the milk protein were monitored by measuring the protein-bound carbonyls and PAGE protein profiles. The results showed that the amount of protein-bound carbonyls increased after Maillard reaction (MR). In addition, sodium dodecyl sulfate-PAGE analysis indicated a formation of high-molecular weight complexes through MR. The modification sites induced by MR of milk protein were monitored by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of tryptic-digested gel spots of MRP. As a result, modification and their localization in AA sequence of MRP was identified. Also, the MRP showed higher antioxidant activities than the intact milk protein, and they reduced intracellular reactive oxygen species production and inhibited the depletion of the reduced glutathione concentrations in the HepG2 cells. In particular, glucose-sodium caseinate MRP showed the highest biological activities among all MRP. Therefore, these results suggest that the MRP from milk protein reacting with sugars possess effective antioxidant activity and have a protective ability against oxidative damage. PMID:26627852

  18. Cytotoxicity of aflatoxin B1 and its chemically synthesised epoxide derivative on the A549 human epithelioid lung cell line.

    PubMed

    Palanee, T; Dutton, M F; Chuturgoon, A A

    2001-01-01

    Aflatoxin B1 (AFB1 ) is a carcinogenic mycotoxin found in feeds and in airborne grain dusts. Aflatoxin B1 requires biotransformation to the AFB1-8,9 epoxide (AFBO) by a bioactivation system and subsequent covalent binding to DNA or proteins, to exert its carcinogenic potential. The lung contains cytochrome P450, prostaglandin-H-synthase, lipoxygenase, epoxide hydrolase and other bioactivation enzymes, and is thus a potential target for the effects of AFB1 via the routes of inhalation and ingestion. The A549 human epithelioid lung cell line and the methylthiazol tetrazolium (MTT) bioassay were used to investigate the cytotoxicity of AFB1 and its chemically synthesised epoxide (AFBO) in vitro. Statistical analysis of the MTT results indicated that there were overall significant differences between the control and both the AFB1-treated (p < 0.0001) and AFBO-treated cells (p = 0.002). However, there was no significant difference between AFB1 and AFBO-treated cells, when the entire range of concentrations were assessed against each other (p = 0.2877). When analysed at each concentration, only at 0.01 mM was there a significant difference between the effects of AFB1 and AFBO (p = 0.0358). The results of this investigation show that AFB1 and AFBO are both cytotoxic in the A549 cell line. PMID:11678590

  19. Membranes as programmable matter: modulating physical-chemical behavior in lipid ensembles derived from archaea and eukaryotes

    NASA Astrophysics Data System (ADS)

    Gilmore, Sean Fitzpatrick

    Lipid membranes are of general interest to the scientific community due to their roles as cellular membranes, and because of their interesting material properties, such as tendencies to self-assemble into two- and three-dimensional structures. Further, there is interest in using lipid membranes as a self-assembling template or substrate for other materials, such as membrane proteins. The work presented here explores the physical-chemical interactions in and around artificial lipid membranes. In the first two chapters, lipid membranes are investigated as a form of programmable matter that responds to environmental changes. These responses manifest as two- and three-dimensional reorganization. In the subsequent chapters, the lipids of an extremophilic archaeon are examined in synthetic configurations to 1) identify how ensembles of lipids originating from organisms of different domains on the tree of life may behave in similar ways, and 2) to examine how the lipids of a desiccation-tolerant organism may be used to create robust lipid (bilayer) membranes that do not rely on liquid water to retain their structure. These collected findings expand how living membranes may be modulated or reorganized in vivo, and also suggest new ways to create programmable lipid-based materials.

  20. Influence of stoichiometry on the optical and electrical properties of chemical vapor deposition derived MoS2.

    PubMed

    Kim, In Soo; Sangwan, Vinod K; Jariwala, Deep; Wood, Joshua D; Park, Spencer; Chen, Kan-Sheng; Shi, Fengyuan; Ruiz-Zepeda, Francisco; Ponce, Arturo; Jose-Yacaman, Miguel; Dravid, Vinayak P; Marks, Tobin J; Hersam, Mark C; Lauhon, Lincoln J

    2014-10-28

    Ultrathin transition metal dichalcogenides (TMDCs) of Mo and W show great potential for digital electronics and optoelectronic applications. Whereas early studies were limited to mechanically exfoliated flakes, the large-area synthesis of 2D TMDCs has now been realized by chemical vapor deposition (CVD) based on a sulfurization reaction. The optoelectronic properties of CVD grown monolayer MoS2 have been intensively investigated, but the influence of stoichiometry on the electrical and optical properties has been largely overlooked. Here we systematically vary the stoichiometry of monolayer MoS2 during CVD via controlled sulfurization and investigate the associated changes in photoluminescence and electrical properties. X-ray photoelectron spectroscopy is employed to measure relative variations in stoichiometry and the persistence of MoOx species. As MoS2-? is reduced (increasing ?), the field-effect mobility of monolayer transistors increases while the photoluminescence yield becomes nonuniform. Devices fabricated from monolayers with the lowest sulfur content have negligible hysteresis and a threshold voltage of ? 0 V. We conclude that the electrical and optical properties of monolayer MoS2 crystals can be tuned via stoichiometry engineering to meet the requirements of various applications. PMID:25223821

  1. Dislocation substructure of mantle-derived olivine as revealed by selective chemical etching and transmission electron microscopy

    USGS Publications Warehouse

    Kirby, S.H.; Wegner, M.W.

    1978-01-01

    Cleaved and mechanically polished surfaces of olivine from peridotite xenoliths from San Carlos, Arizona, were chemically etched using the techniques of Wegner and Christie (1974). Dislocation etch pits are produced on all surface orientations and they tend to be preferentially aligned along the traces of subgrain boundaries, which are approximately parallel to (100), (010), and (001). Shallow channels were also produced on (010) surfaces and represent dislocations near the surface that are etched out along their lengths. The dislocation etch channel loops are often concentric, and emanate from (100) subgrain boundaries, which suggests that dislocation sources are in the boundaries. Data on subgrain misorientation and dislocation line orientation and arguments based on subgrain boundary energy minimization are used to characterize the dislocation structures of the subgrain boundaries. (010) subgrain boundaries are of the twist type, composed of networks of [100] and [001] screw dislocations. Both (100) and (001) subgrain boundaries are tilt walls composed of arrays of edge dislocation with Burgers vectors b=[100] and [001], respectively. The inferred slip systems are {001} ???100???, {100} ???001???, and {010} ???100??? in order of diminishing importance. Exploratory transmission electron microscopy is in accord with these identifications. The flow stresses associated with the development of the subgrain structure are estimated from the densities of free dislocations and from the subgrain dimensions. Inferred stresses range from 35 to 75 bars using the free dislocation densities and 20 to 100 bars using the subgrain sizes. ?? 1978 Springer-Verlag.

  2. Isolation and chemical identification of lipid derivatives from avocado (Persea americana) pulp with antiplatelet and antithrombotic activities.

    PubMed

    Rodriguez-Sanchez, Dariana Graciela; Flores-García, Mirthala; Silva-Platas, Christian; Rizzo, Sheryl; Torre-Amione, Guillermo; De la Peña-Diaz, Aurora; Hernández-Brenes, Carmen; García-Rivas, Gerardo

    2015-01-01

    Platelets play a pivotal role in physiological hemostasis. However, in coronary arteries damaged by atherosclerosis, enhanced platelet aggregation, with subsequent thrombus formation, is a precipitating factor in acute ischemic events. Avocado pulp (Persea americana) is a good source of bioactive compounds, and its inclusion in the diet as a source of fatty acid has been related to reduced platelet aggregability. Nevertheless, constituents of avocado pulp with antiplatelet activity remain unknown. The present study aims to characterize the chemical nature of avocado constituents with inhibitory effects on platelet aggregation. Centrifugal partition chromatography (CPC) was used as a fractionation and purification tool, guided by an in vitro adenosine diphosphate (ADP), arachidonic acid or collagen-platelet aggregation assay. Antiplatelet activity was initially linked to seven acetogenins that were further purified, and their dose-dependent effects in the presence of various agonists were contrasted. This process led to the identification of Persenone-C (3) as the most potent antiplatelet acetogenin (IC₅₀=3.4 mM) among the evaluated compounds. In vivo evaluations with Persenone A (4) demonstrated potential protective effects against arterial thrombosis (25 mg kg⁻¹ of body weight), as coagulation times increased (2-fold with respect to the vehicle) and thrombus formation was attenuated (71% versus vehicle). From these results, avocado may be referred to as a functional food containing acetogenin compounds that inhibit platelet aggregation with a potential preventive effect on thrombus formation, such as those that occur in ischaemic diseases. PMID:25319210

  3. Process related effects on the chemical and toxicologic characteristics of coal derived fuels. [Changes over 25 day run

    SciTech Connect

    Wright, C.W.; Chess, E.K.; Bean, R.M.; Mahlum, D.D.; Stewart, D.L.; Wilson, B.W.

    1986-04-01

    As a component of an ongoing program to assess the potential health effects of coal conversion materials, the authors have recently completed chemical and toxicologic studies of a sample set collected on selected days of a 25-day demonstration run of a catalytic two stage direct coal liquefaction (CTSL) process. There was an increase in heteroatomic, nitrogen containing polycyclic aromatic compounds (NPAC) and hydroxy-substituted PAC, compounds as the operation time of the pilot plant increased. The proportion of material which boiled above 975/sup 0/F also increased in the solids-free portion of the recycle slurry oil as pilot plant operation time increased. As anticipated from the increase in NPAC concentration during the run, the microbial mutagenic activity of selected process materials also increased as a function of run time. Likewise, the tumorigenicity of the materials produced later in the demonstration run was higher than that of those produced initially. These results support the view that catalyst deactivation during the course of the run gives rise not only to lower coal conversion, but also to increased toxicologic activity.

  4. Influence of Stoichiometry on the Optical and Electrical Properties of Chemical Vapor Deposition Derived MoS2

    PubMed Central

    2015-01-01

    Ultrathin transition metal dichalcogenides (TMDCs) of Mo and W show great potential for digital electronics and optoelectronic applications. Whereas early studies were limited to mechanically exfoliated flakes, the large-area synthesis of 2D TMDCs has now been realized by chemical vapor deposition (CVD) based on a sulfurization reaction. The optoelectronic properties of CVD grown monolayer MoS2 have been intensively investigated, but the influence of stoichiometry on the electrical and optical properties has been largely overlooked. Here we systematically vary the stoichiometry of monolayer MoS2 during CVD via controlled sulfurization and investigate the associated changes in photoluminescence and electrical properties. X-ray photoelectron spectroscopy is employed to measure relative variations in stoichiometry and the persistence of MoOx species. As MoS2?? is reduced (increasing ?), the field-effect mobility of monolayer transistors increases while the photoluminescence yield becomes nonuniform. Devices fabricated from monolayers with the lowest sulfur content have negligible hysteresis and a threshold voltage of ?0 V. We conclude that the electrical and optical properties of monolayer MoS2 crystals can be tuned via stoichiometry engineering to meet the requirements of various applications. PMID:25223821

  5. Application studies of activated carbon derived from rice husks produced by chemical-thermal process--a review.

    PubMed

    Chen, Yue; Zhu, Yanchao; Wang, Zichen; Li, Ying; Wang, Lili; Ding, Lili; Gao, Xiaoyan; Ma, Yuejia; Guo, Yupeng

    2011-03-15

    The production of functional activated carbon materials starting from cheap natural precursors using environmentally friendly processes is a highly attractive subject in material chemistry today. Recently, much attention has been focused on the use of plant biomass to produce functional carbonaceous materials, encompassing economic, environmental and social issues. Besides the classical route to produce activated carbons from fossil materials, rice husk shows clear advantages in that it can generate a variety of cheap and sustainable carbonaceous materials with attractive nanostructure and functional patterns for a wide range of applications. From a comprehensive literature review, it was found that porous carbon that derived from rice husks, in addition to having wide availability, has fast kinetics and appreciable adsorption capacities too. Porous carbon materials also play a significant role in new applications such as catalytic supports, battery electrodes, capacitors, and gas storage. In this review, an extensive list of rice husks literature has been compiled. Conclusions have been drawn from the literature reviewed, and suggestions for future research are proposed. PMID:21353192

  6. Receptor-specific scoring functions derived from quantum chemical models improve affinity estimates for in-silico drug discovery.

    PubMed

    Fischer, Bernhard; Fukuzawa, Kaori; Wenzel, Wolfgang

    2008-03-01

    The adaptation of forcefield-based scoring function to specific receptors remains an important challenge for in-silico drug discovery. Here we compare binding energies of forcefield-based scoring functions with models that are reparameterized on the basis of large-scale quantum calculations of the receptor. We compute binding energies of eleven ligands to the human estrogen receptor subtype alpha (ERalpha) and four ligands to the human retinoic acid receptor of isotype gamma (RARgamma). Using the FlexScreen all-atom receptor-ligand docking approach, we compare docking simulations parameterized by quantum-mechanical calculation of a large protein fragment with purely forcefield-based models. The use of receptor flexibility in the FlexScreen permits the treatment of all ligands in the same receptor model. We find a high correlation between the classical binding energy obtained in the docking simulation and quantum mechanical binding energies and a good correlation with experimental affinities R=0.81 for ERalpha and R=0.95 for RARgamma using the quantum derived scoring functions. A significant part of this improvement is retained, when only the receptor is treated with quantum-based parameters, while the ligands are parameterized with a purely classical model. PMID:17876816

  7. Study of chemical reactivity in relation to experimental parameters of efficiency in coumarin derivatives for dye sensitized solar cells using DFT.

    PubMed

    Soto-Rojo, Rody; Baldenebro-López, Jesús; Glossman-Mitnik, Daniel

    2015-06-01

    A group of dyes derived from coumarin was studied, which consisted of nine molecules using a very similar manufacturing process of dye sensitized solar cells (DSSCs). Optimized geometries, energy levels of the highest occupied molecular orbital and the lowest unoccupied molecular orbital, and ultraviolet-visible spectra were obtained using theoretical calculations, and they were also compared with experimental conversion efficiencies of the DSSC. The representation of an excited state in terms of natural transition orbitals (NTOs) was studied. Chemical reactivity parameters were calculated and correlated with the experimental data linked to the efficiency of the DSSC. A new proposal was obtained to design new molecular systems and to predict their potential use as a dye in DSSCs. PMID:25959071

  8. Microwave plasma enhanced chemical vapor deposition growth of few-walled carbon nanotubes using catalyst derived from an iron-containing block copolymer precursor.

    PubMed

    Wang, Peng; Lu, Jennifer; Zhou, Otto

    2008-05-01

    The microwave plasma enhanced chemical vapor deposition (MPECVD) method is now commonly used for directional and conformal growth of carbon nanotubes (CNTs) on supporting substrates. One of the shortcomings of the current process is the lack of control of the diameter and diameter distribution of the CNTs due to difficulties in synthesizing well-dispersed catalysts. Recently, block copolymer derived catalysts have been developed which offer the potential of fine control of both the size of and the spacing between the metal clusters. In this paper we report the successful growth of CNTs with narrow diameter distribution using polystyrene-block-polyferrocenylethylmethylsilane (PS-b-PFEMS) as the catalyst precursor. The study shows that higher growth pressure leads to better CNT growth. Besides the pressure, the effects on the growth of CNTs of the growth parameters, such as temperature and precursor gas ratio, are also studied. PMID:21825693

  9. Physico-chemical characteristics of coated silicone textured versus smooth breast implants differentially influence breast-derived fibroblast morphology and behaviour.

    PubMed

    Valencia-Lazcano, Anai A; Alonso-Rasgado, Teresa; Bayat, Ardeshir

    2014-12-01

    Capsule formation is an inevitable consequence of silicone breast implantation. Clinically challenging dense fibrocollagenous capsular contractures occur at different rates between smooth compared to textured surfaces. Host response is influenced by several factors including implant surface texture, chemistry and interactions between cells and the extracellular matrix (ECM). Specific coatings can modify the physico-chemical properties of implant surfaces eliciting specific cellular reactions. Therefore, we evaluated the physico-chemical characteristics of coated smooth versus textured silicone breast implants on breast-derived fibroblast morphology and behaviour using (a) confocal laser microscopy, (b) Raman spectroscopy and (c) the effect of four unique protein and glycosaminoglycan (GAG) coatings (aggrecan, collagen I, fibronectin and hyaluronic acid) on breast-derived fibroblast attachment, proliferation, morphology, spreading, cytotoxicity and gene expression. Collagen I, fibronectin and hyaluronic acid coatings exhibited satisfactory fibroblast adhesion (p<0.001) in comparison to uncoated surfaces. Cell adhesion was less on smooth surfaces compared to textured surfaces (p<0.001). Fibroblasts cultured on collagen I, fibronectin and hyaluronic acid coated implants demonstrated improved cell proliferation than uncoated surfaces (p<0.001). LDH assay showed that coating surfaces with collagen I, fibronectin and hyaluronic acid did not induce cytotoxicity. Alpha-actinin expression and fibroblast adhesion to the substrate were upregulated (p<0.001), in textured versus smooth surfaces. FAK, vinculin and paxillin expression were upregulated (p<0.001), in all surfaces coated with fibronectin and collagen I. In conclusion, we present original data for expression of adhesion-related genes, cell morphology and proliferation in breast fibroblasts following the application of specific coatings on breast implant surfaces. PMID:25238227

  10. Chemical solution deposition derived (001)-oriented epitaxial BiFeO{sub 3} thin films with robust ferroelectric properties using stoichiometric precursors (invited)

    SciTech Connect

    Zhang, Qi; Valanoor, Nagarajan; Standard, Owen

    2014-08-14

    Phase pure bismuth ferrite (BiFeO{sub 3}) thin films with (001)-oriented epitaxial structure are realized on lanthanum strontium manganite (La{sub 0.67}Sr{sub 0.33}MnO{sub 3}) buffered (001)-SrTiO{sub 3} substrates by chemical solution deposition. The annealing process is optimized such that a stoichiometric precursor can be used to accurately control the Bi:Fe ratio. Ferroelectric, dielectric, and resistive switching behaviours are investigated for 40?nm, 70?nm, and 150?nm BFO thin films. While the thinnest film (40?nm) shows very leaky loops, square and fully saturated polarization hysteresis loops are shown for the thicker films. The highest remanent polarization (2P{sub r}?=?100??C/cm{sup 2}) and relative dielectric constant (?{sub r}?=?613) are obtained in the 150?nm BFO thin film. High cycle fatigue tests show that the thick films are resistant to polarization fatigue. Piezoresponse force microscopy results show that the domain structure varies with thickness. Resistive switching and polarization mediated diode effects are also observed. These robust properties suggest that chemical solution deposition derived BiFeO{sub 3} thin films can offer a viable low cost alternative.

  11. Computational and Experimental Assessment of Benzene Cation Chemistry for the Measurement of Marine Derived Biogenic Volatile Organic Compounds with Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zoerb, M.; Kim, M.; Zimmermann, K.; Bertram, T. H.

    2013-12-01

    Chemical ionization mass spectrometry (CIMS) is a highly selective and sensitive technique for the measurement of trace gases in the atmosphere. However, competing side reactions and dependence on relative humidity (RH) can make the transition from the laboratory to the field challenging. Effective implementation of chemical ionization requires a thorough knowledge of the elementary steps leading to ionization of the analyte. We have recently investigated benzene cations for the detection of marine derived biogenic volatile organic compounds (BVOCs), such isoprene and terpene compounds, from algal bloom events. Our experimental results indicate that benzene ion chemistry is an attractive candidate for field measurements, and the RH dependence is weak. To further understand the advantages and limitations of this approach, we have also used electronic structure theory calculations to compliment the experimental work. These theoretical methods can provide valuable insight into the physical chemistry of ion molecule reactions including thermodynamical information, the stability of ions to fragmentation, and potential sources of interference such as dehydration to form isobaric ions. The combined experimental and computational approach also allows validation of the theoretical methods and will provide useful information towards gaining predictive power for the selection of appropriate reagent ions for future experiments.

  12. Quantum chemical investigation and statistical analysis of the relationship between corrosion inhibition efficiency and molecular structure of xanthene and its derivatives on mild steel in sulphuric acid

    NASA Astrophysics Data System (ADS)

    Obi-Egbedi, N. O.; Obot, I. B.; El-Khaiary, Mohammad I.

    2011-09-01

    A density functional theory (DFT) study of xanthene (XEN) and two of its derivatives namely xanthone (XAN) and xanthione (XION) recently used as corrosion inhibitors for mild steel in 0.5 M H 2SO 4 was undertaken at the B3LYP/631G (d) level. Inhibition efficiency obtained experimentally followed the order: XEN < XAN < XION. It was found that when the organic molecules adsorbed on the steel surface, molecular structure influences their interaction mechanism and by extension their inhibition efficiencies. The quantum chemical properties/descriptors most relevant to their potential action as corrosion inhibitors have been calculated in the neutral and protonated forms in aqueous phase for comparison. They include: Total energy (TE), EHOMO, ELUMO, energy gap (? E), dipole moment ( D), molecular area (MA), molecular volume (MV), hardness (?), softness ( ??), the fractions of electrons transferred (? N), electrophilicity index (?) and total energy change (? ET). The quantum chemical parameters/descriptors were correlated with inhibition effect of the three inhibitors and were further used to explain the electron transfer mechanism between the inhibitors and the steel surface. Furthermore, equations were proposed using the non-linear and the multiple-linear regression analysis. The theoretical obtained results were found to be consistent with the experimental data reported.

  13. Liquid chromatography tandem mass spectrometry determination of chemical markers and principal component analysis of Vitex agnus-castus L. fruits (Verbenaceae) and derived food supplements.

    PubMed

    Mari, Angela; Montoro, Paola; Pizza, Cosimo; Piacente, Sonia

    2012-11-01

    A validated analytical method for the quantitative determination of seven chemical markers occurring in a hydroalcoholic extract of Vitex agnus-castus fruits by liquid chromatography electrospray triple quadrupole tandem mass spectrometry (LC/ESI/(QqQ)MSMS) is reported. To carry out a comparative study, five commercial food supplements corresponding to hydroalcoholic extracts of V. agnus-castus fruits were analysed under the same chromatographic conditions of the crude extract. Principal component analysis (PCA), based only on the variation of the amount of the seven chemical markers, was applied in order to find similarities between the hydroalcoholic extract and the food supplements. A second PCA analysis was carried out considering the whole spectroscopic data deriving from liquid chromatography electrospray linear ion trap mass spectrometry (LC/ESI/(LIT)MS) analysis. High similarity between the two PCA was observed, showing the possibility to select one of these two approaches for future applications in the field of comparative analysis of food supplements and quality control procedures. PMID:22840980

  14. Common Host-Derived Chemicals Increase Catches of Disease-Transmitting Mosquitoes and Can Improve Early Warning Systems for Rift Valley Fever Virus

    PubMed Central

    Tchouassi, David P.; Sang, Rosemary; Sole, Catherine L.; Bastos, Armanda D. S.; Teal, Peter E. A.; Borgemeister, Christian; Torto, Baldwyn

    2013-01-01

    Rift Valley fever (RVF), a mosquito-borne zoonosis, is a major public health and veterinary problem in sub-Saharan Africa. Surveillance to monitor mosquito populations during the inter-epidemic period (IEP) and viral activity in these vectors is critical to informing public health decisions for early warning and control of the disease. Using a combination of field bioassays, electrophysiological and chemical analyses we demonstrated that skin-derived aldehydes (heptanal, octanal, nonanal, decanal) common to RVF virus (RVFV) hosts including sheep, cow, donkey, goat and human serve as potent attractants for RVFV mosquito vectors. Furthermore, a blend formulated from the four aldehydes and combined with CO2-baited CDC trap without a light bulb doubled to tripled trap captures compared to control traps baited with CO2 alone. Our results reveal that (a) because of the commonality of the host chemical signature required for attraction, the host-vector interaction appears to favor the mosquito vector allowing it to find and opportunistically feed on a wide range of mammalian hosts of the disease, and (b) the sensitivity, specificity and superiority of this trapping system offers the potential for its wider use in surveillance programs for RVFV mosquito vectors especially during the IEP. PMID:23326620

  15. Lead and copper immobilization in a shooting range soil using soybean stover- and pine needle-derived biochars: Chemical, microbial and spectroscopic assessments.

    PubMed

    Ahmad, Mahtab; Ok, Yong Sik; Rajapaksha, Anushka Upamali; Lim, Jung Eun; Kim, Byung-Yong; Ahn, Jae-Hyung; Lee, Young Han; Al-Wabel, Mohammad I; Lee, Sung-Eun; Lee, Sang Soo

    2016-01-15

    Biochar (BC) could be a potential candidate for the remediation of metal contaminated soil. Mechanistic understandings are needed for the appropriate selection of BC and investigating molecular microbial ecological interactions. The soybean stover-derived BCs were more effective in immobilizing Pb (88%) and Cu (87%) than the pine needle-derived BCs in a contaminated shooting range soil. The sequential chemical extractions indicated that BCs stimulated the geochemical transformation of metal species. Spectroscopic investigations using scanning electron microscopic elemental dot mapping and extended X-ray absorption fine structure spectroscopic measurements showed that Pb in the BCs amended soils was immobilized by the formation of stable chloropyromorphite. Soil organic C and microbial activity were also enhanced by BC. The non-labile C fraction in the soil amended with BCs produced at 700C was increased. Biochars showed less impact on the bacterial community than feedstock biomass as promulgated by the pyrosequencing of 16S rRNA gene. The feedstock type (namely soybean stover and pine needles) was the main factor influencing the BCs efficacy on metals' (im) mobilization and bacterial health in soils. PMID:26355413

  16. Structural determination of oligosaccharides derived from lipooligosaccharide of Neisseria gonorrhoeae F62 by chemical, enzymatic, and two-dimensional NMR methods

    SciTech Connect

    Yamasaki, Ryohei; Nasholds, W.; Griffiss, J.M. Veterans Administration Medical Center, San Francisco, CA ); Bacon, B.E. ); Schneider, H. )

    1991-10-29

    F62 LOS of Neisseria gonorrhoeae consists of two major LOS components; the higher and smaller molecular weight (MW) components were recognized by MAbs 1-1-M and 3F11 respectively. Base-line separation of the two major oligosaccharide (OS) components from F62 LOS was achieved by Bio-Gel P-4 chromatography after dephosphorylation of the OS mixture. The structures of the two major OSs were studied by chemical, enzymatic, and 2D NMR methods as well as methylation followed by GC/MS analysis. The OS component derived from the MAb 1-1-M defined LOS component was determined to have a V{sup 3}-({beta}-N-acetylgalactosaminyl)neolactotetraose structure at one of its nonreducing termini. The OS component derived from the MAb 3F11 defined LOS component did not have a GalNAc residue. The rest of its structure was identical to that of the OS-1, and a neolactotetraose is exposed at its nonreducing terminus.

  17. Topoisomerase II DNA cleavage stimulation, DNA binding activity, cytotoxicity, and physico-chemical properties of 2-aza- and 2-aza-oxide-anthracenedione derivatives.

    PubMed

    De Isabella, P; Palumbo, M; Sissi, C; Capranico, G; Carenini, N; Menta, E; Oliva, A; Spinelli, S; Krapcho, A P; Giuliani, F C

    1995-07-01

    The cytotoxic activity of mitoxantrone and related anthracenediones has been ascribed to the ability of these compounds to interfere with DNA topoisomerase II function, resulting in DNA cleavage stimulation. The molecular details of enzyme inhibition by these intercalating agents remain to be defined. In an attempt to identify the structural determinants for optimal activity, the molecular and cellular effects of a series of heteroanalogues bearing different side-chains were examined in relation to the physico-chemical and DNA binding properties of these compounds. The results indicated that substitution of a pyridine ring for the dihydroxyphenylene ring in the planar chromophore caused a marked reduction of cytotoxic activity and of the ability to stimulate topoisomerase II-mediated DNA damage in intact cells and with simian virus 40 DNA in vitro. Although all tested derivatives were shown to intercalate into DNA, their DNA binding affinities were appreciably lower than that of mitoxantrone. The behavior of 2-aza derivatives more closely resembled that of ametantrone, suggesting that the potency of agents of this class is influenced more by the presence of hydroxyl groups than by the phenylene ring. The observation that a dramatic reduction (or loss) of the ability of aza derivatives to stimulate DNA cleavage is associated with a marked reduction of cytotoxic potency supports a primary role of topoisomerase II-mediated effects in the mechanism of action of the effective agents of this class. Because appreciable cytotoxic activity and significant in vivo antitumor efficacy are retained by compounds inactive (or poorly active) in inhibition of topoisomerase II, these results are consistent with multiple effects of anthracenediones at the cellular level. PMID:7623772

  18. Sol-gel-derived NiO/NiAl{sub 2}O{sub 4} oxygen carriers for chemical-looping combustion by coal char

    SciTech Connect

    Haibo Zhao; Liming Liu; Baowen Wang; Di Xu; Linlin Jiang; Chuguang Zheng

    2008-03-15

    This paper focuses on the investigation of Ni-based oxygen carriers for CLC by coal char. First, Al(OC{sub 3}H{sub 7}){sub 3} and Ni(NO{sub 3}){sub 2} are selected as the main raw materials to prepare sol-gel-derived NiO/NiAl{sub 2}O{sub 4} oxygen carriers. The oxygen carrier with a mass content of 60% NiO, a sintering temperature of 1300{sup o}C, and a sintering time of 6 h performs comparatively well. Second, the reduction reaction of the NiO/NiAl{sub 2}O{sub 4} oxygen carriers with char and the circular reduction/oxidation reactions of the NiO/NiAl{sub 2}O{sub 4} oxygen carriers with char/air or hydrogen/air are carried out in a thermogravimetric analysis (TGA) instrument to investigate the reactivities and chemical life of the prepared NiO/NiAl{sub 2}O{sub 4} oxygen carriers. The experimental results show that (a) when the TGA temperature is higher than 850{sup o}C, NiO/NiAl{sub 2}O{sub 4} starts to react with coal char rapidly, which indicates that CLC of coal char using NiO/NiAl{sub 2}O{sub 4} as oxygen carriers is a feasible technology of energy utilization in principle; (b) NiO/NiAl{sub 2}O{sub 4}, which maintains its activity over single-cycle reduction/oxidation reactions with char/air or multiple-cycle reduction/oxidation reactions with hydrogen/air, exhibits extremely good recyclablity; (c) the porous beehive structure of the NiO/NiAl{sub 2}O{sub 4} particle is maintained, and the sintering behavior between different particles is not observed during cyclic studies. Those experimental results prove the sol-gel-derived oxygen carrier NiO/NiAl{sub 2}O{sub 4} is capable of being used in chemical-looping combustion fueled by coal char or H{sub 2}. 51 refs., 5 figs., 5 tabs.

  19. Cross-shelf and along-shelf nutrient fluxes derived from flow fields and chemical hydrography observed in the southern East China Sea off northern Taiwan

    NASA Astrophysics Data System (ADS)

    Liu, Kon-Kee; Yung Tang, Tswen; Gong, Gwo-Ching; Chen, Liang-Yu; Shiah, Fuh-Kwo

    2000-03-01

    Cross-shelf exchange of nutrients (N, P and Si) off northeastern Taiwan and along-shelf transports just north of the Taiwan Strait was assessed using chemical hydrography and velocity fields observed in August 1994 (summer) and March 1997 (winter). The summer survey was conducted along the periphery of a triangle. The velocity field was determined by phase-averaged current velocities measured with ship-borne ADCP on two rounds separated by 3.5 cycles of the dominant M 2 tide. Nutrient distributions were derived from phase-averaged hydrographic data. Although the inflowing and outflowing volume transports were mismatched by 14% largely due to poorly estimated surface flow that carried little nutrients, the inputs and outputs of nutrients agreed within 2-5%. Such consistency lends support to the adopted approach for estimating nutrient fluxes. The winter survey, which provided observations on two transects, one along-shelf and one cross-shelf, was conducted using two ships separated by 1/2 cycle of the M 2 tide. Results from the two ships allowed determination of the phase-averaged flow fields and chemical hydrography. The two surveys indicated that the Kuroshio upwelling provided rather constant nutrient fluxes to the shelf, which were comparable to the total nutrient influxes from slope waters to the Mid and South Atlantic Bight and considerably larger than the riverine sources. Significant amounts of nutrients from the shelf leaked back into the surface layer of the Kuroshio, replenishing its impoverished nutrient reserves. Along-shelf nutrient fluxes from the Taiwan Strait changed drastically between seasons, ranging from less than half to more than double the Kuroshio inputs. In the light of the variability of the shelf environment, more observations are needed to better determine the mean condition of this transport.

  20. The chemically synthesized ageladine A-derivative LysoGlow84 stains lysosomes in viable mammalian brain cells and specific structures in the marine flatworm Macrostomum lignano.

    PubMed

    Mordhorst, Thorsten; Awal, Sushil; Jordan, Sebastian; Petters, Charlotte; Sartoris, Linda; Dringen, Ralf; Bickmeyer, Ulf

    2015-02-01

    Based on the chemical structure and the known chemical synthesis of the marine sponge alkaloid ageladine A, we synthesized the ageladine A-derivative 4-(naphthalene-2-yl)-1H-imidazo[4,5-c]pyridine trifluoroacetate (LysoGlow84). The two-step synthesis started with the Pictet-Spengler reaction of histamine and naphthalene-2-carbaldehyde to a tetrahydropyridine intermediate, which was dehydrogenated with activated manganese (IV) oxide to LysoGlow84. Structure and purity of the synthesized LysoGlow84 were confirmed by NMR spectroscopy and mass spectrometry. The fluorescence intensity emitted by LysoGlow84 depended strongly on the pH of the solvent with highest fluorescence intensity recorded at pH 4. The fluorescence maximum (at 315 nm excitation) was observed at 440 nm. Biocompatibility of LysoGlow84 was investigated using cultured rat brain astrocytes and the marine flatworm Macrostomum lignano. Exposure of the astrocytes for up to 6 h to micromolar concentrations of LysoGlow84 did not compromise cell viability, as demonstrated by several viability assays, but revealed a promising property of this compound for staining of cellular vesicles. Conventional fluorescence microscopy as well as confocal scanning microscopy of LysoGlow84-treated astrocytes revealed co-localization of LysoGlow84 fluorescence with that of LysoTracker Red DND-99. LysoGlow84 stained unclear structures in Macrostomum lignano, which were identified as lysosomes by co-staining with LysoTracker. Strong fluorescence staining by LysoGlow84 was further observed around the worms' anterior gut and the female genital pore which were not counterstained by LysoTracker Red. Thus, LysoGlow84 is a new promising dye that stains lysosomes and other acidic compartments in cultured cells and in worms. PMID:25679913

  1. Chemical activation in Rhinella arenarum oocytes: effect of dehydroleucodine (DhL) and its hydrogenated derivative (2H-DhL).

    PubMed

    Medina, M F; Bühler, M I; Sánchez-Toranzo, G

    2015-12-01

    Mature oocytes are arrested in metaphase II due to the presence of high levels of active maturation promoting factor (MPF). After fertilization, active MPF levels decline abruptly, enabling oocytes to complete meiosis II. One of the first and universal events of oocyte activation is an increase in cytosolic Ca2+ that would be responsible for MPF inactivation. Mature oocytes can also be activated by parthenogenetic activation. The aims of this work are to test the ability of dehydroleucodine (DhL) and its hydrogenated derivative 11,13-dihydro-dehydroleucodine (2H-DhL) to induce chemical activation in amphibian oocytes and to study the participation of calcium in the process. Results indicated that DhL and 2H-DhL induced oocyte activation in a dose-dependent manner. After 90 min of treatment, DhL 36 μM was able to induce 95% activation, while 2H-DhL 36 μM was less active, with only 40% activation. Our results suggest that DhL induced the inhibition of MPF activity, probably by an increase in intracellular Ca2+ concentration. Extracellular Ca2+ would not be significant, although Ca2+ release from intracellular stores is critical. In this sense, IP3Rs and RyRs were involved in the Ca2+ transient induced by lactones. In this species, RyRs appears to be the largest contributor to Ca2+ release in DhL-induced activation. Although more studies are needed on the mechanism of action through which these lactones induce oocyte activation in Rhinella arenarum, the results of this research provide interesting perspectives for the use of these lactones as chemical activators in in vitro fertilization and cloning. PMID:25424172

  2. The Chemically Synthesized Ageladine A-Derivative LysoGlow84 Stains Lysosomes in Viable Mammalian Brain Cells and Specific Structures in the Marine Flatworm Macrostomum lignano

    PubMed Central

    Mordhorst, Thorsten; Awal, Sushil; Jordan, Sebastian; Petters, Charlotte; Sartoris, Linda; Dringen, Ralf; Bickmeyer, Ulf

    2015-01-01

    Based on the chemical structure and the known chemical synthesis of the marine sponge alkaloid ageladine A, we synthesized the ageladine A-derivative 4-(naphthalene-2-yl)-1H-imidazo[4,5-c]pyridine trifluoroacetate (LysoGlow84). The two-step synthesis started with the Pictet-Spengler reaction of histamine and naphthalene-2-carbaldehyde to a tetrahydropyridine intermediate, which was dehydrogenated with activated manganese (IV) oxide to LysoGlow84. Structure and purity of the synthesized LysoGlow84 were confirmed by NMR spectroscopy and mass spectrometry. The fluorescence intensity emitted by LysoGlow84 depended strongly on the pH of the solvent with highest fluorescence intensity recorded at pH 4. The fluorescence maximum (at 315 nm excitation) was observed at 440 nm. Biocompatibility of LysoGlow84 was investigated using cultured rat brain astrocytes and the marine flatworm Macrostomum lignano. Exposure of the astrocytes for up to 6 h to micromolar concentrations of LysoGlow84 did not compromise cell viability, as demonstrated by several viability assays, but revealed a promising property of this compound for staining of cellular vesicles. Conventional fluorescence microscopy as well as confocal scanning microscopy of LysoGlow84-treated astrocytes revealed co-localization of LysoGlow84 fluorescence with that of LysoTracker® Red DND-99. LysoGlow84 stained unclear structures in Macrostomum lignano, which were identified as lysosomes by co-staining with LysoTracker. Strong fluorescence staining by LysoGlow84 was further observed around the worms’ anterior gut and the female genital pore which were not counterstained by LysoTracker Red. Thus, LysoGlow84 is a new promising dye that stains lysosomes and other acidic compartments in cultured cells and in worms. PMID:25679913

  3. Chemical microsensors

    DOEpatents

    Li, DeQuan (Los Alamos, NM); Swanson, Basil I. (Los Alamos, NM)

    1995-01-01

    An article of manufacture is provided including a substrate having an oxide surface layer and a selective thin film of a cyclodextrin derivative chemically bound upon said substrate, said film is adapted for the inclusion of a selected organic compound therewith. Such an article can be either a chemical sensor capable of detecting a resultant mass change from inclusion of the selected organic compound or a chemical separator capable of reversibly selectively separating a selected organic compound.

  4. Effect of hydrogen sulfide on chemical looping of coal-derived synthesis gas over bentonite-supported metal---oxide oxygen carriers

    SciTech Connect

    Tian, H.; Simonyi, T.; Poston, J.; Siriwardane, R.

    2009-01-01

    The effect of hydrogen sulfide (H2S) on the chemical looping combustion of coal-derived synthesis gas with bentonite-supported metal oxidesssuch as iron oxide, nickel oxide, manganese oxide, and copper oxideswas investigated by thermogravimetric analysis, mass spectrometry, and X-ray photoelectron spectroscopy (XPS). During the reaction with synthesis gas containing H2S, metal-oxide oxygen carriers were first reduced by carbon monoxide and hydrogen, and then interacted with H2S to form metal sulfide, which resulted in a weight gain during the reduction/sulfidation step. The reduced/sulfurized compounds could be regenerated to form sulfur dioxide and oxides during the oxidation reaction with air. The reduction/oxidation capacities of iron oxide and nickel oxide were not affected by the presence of H2S, but both manganese oxide and copper oxide showed decreased reduction/oxidation capacities. However, the rates of reduction and oxidation decreased in the presence of H2S for all four metal oxides.

  5. Comparative investigation on chemical looping combustion of coal-derived synthesis gas containing H2S over supported NiO oxygen carriers

    SciTech Connect

    Ksepko, E.; Siriwardane, R.; Tian, H.; Simonyi, T.; Sciazko, M.

    2010-01-01

    Chemical looping combustion (CLC) of simulated coal-derived synthesis gas was conducted with NiO oxygen carriers supported on SiO2, ZrO2, TiO2, and sepiolite. The effect of H2S on the performance of these samples for the CLC process was also evaluated. Five-cycle thermogravimetric analysis (TGA) tests at 800 #1;C indicated that all oxygen carriers had a stable performance at 800 #1;C, except NiO/SiO2. Full reduction/oxidation reactions of the oxygen carrier were obtained during the five-cycle test. It was found that support had a significant effect on reaction performance of NiO both in reduction and oxidation rates. The reduction reaction was significantly faster than the oxidation reaction for all oxygen carriers, while the oxidation reaction is fairly slow due to oxygen diffusion on NiO layers. The reaction profile was greatly affected by the presence of H2S, but there was no effect on the capacity due to the presence of H2S in synthesis gas. The presence of H2S decreased reduction reaction rates significantly, but oxidation rates of reduced samples increased. X-ray diffraction (XRD) data of the oxidized samples after a five-cycle test showed stable crystalline phases without any formation of sulfides or sulfites/sulfates. Increase in reaction temperature to 900 #1;C had a positive effect on the performance.

  6. Upgrading oxygenated Fischer-Tropsch derivatives and one-step direct synthesis of ethyl acetate from ethanol - examples of the desirability of research on simple chemical compounds transformations.

    PubMed

    Klimkiewicz, Roman

    2014-01-01

    Oxygenates formed as by-products of Fischer-Tropsch syntheses can be transformed into other Fischer-Tropsch derived oxygenates instead of treating them as unwanted chemicals. One-step direct synthesis of ethyl acetate from ethanol is feasible with the use of some heterogeneous catalysts. Despite their apparent simplicity, both transformations are discussed as targeted fields of research. Furthermore, the two concepts are justified due to the environmental protection. Arguments regarding the Fischer-Tropsch process are focused on the opportunities of the utilization of undesirable by-products. The effective striving for their utilization can make the oxygenates the targeted products of this process. Arguments regarding the one-step direct synthesis of ethyl acetate underline the environmental protection and sustainability as a less waste-generating method but, above all, highlight the possibility of reducing the glycerol overproduction problem. The production of ethyl acetate from bioethanol and then transesterification of fats and oils with the use of ethyl acetate allows managing all the renewable raw materials. Thus, the process enables the biosynthesis of biodiesel without glycerine by-product and potentially would result in the increase in the demand for ethyl acetate. Graphical Abstract. PMID:25648719

  7. Effect of hydrogen sulfide on chemical looping combustion of coal-derived synthesis gas over bentonite-supported metal-oxide oxygen carriers

    SciTech Connect

    Tian, H.J.; Simonyi, T.; Poston, J.; Siriwardane, R.

    2009-09-15

    The effect of hydrogen sulfide (H{sub 2}S) on the chemical looping combustion of coal-derived synthesis gas with bentonite-supported metal oxides - such as iron oxide, nickel oxide, manganese oxide, and copper oxide - was investigated by thermogravimetric analysis, mass spectrometry, and X-ray photoelectron spectroscopy (XPS). During the reaction with synthesis gas containing H{sub 2}S, metal-oxide oxygen carriers were first reduced by carbon monoxide and hydrogen, and then interacted with H{sub 2}S to form metal sulfide, which resulted in a weight gain during the reduction/sulfidation step. The reduced/sulfurized compounds could be regenerated to form sulfur dioxide and oxides during the oxidation reaction with air. The reduction/oxidation capacities of iron oxide and nickel oxide were not affected by the presence of H{sub 2}S, but both manganese oxide and copper oxide showed decreased reduction/oxidation capacities. However, the rates of reduction and oxidation decreased in the presence of H{sub 2}S for all four metal oxides.

  8. Simplified molecular input-line entry system and International Chemical Identifier in the QSAR analysis of styrylquinoline derivatives as HIV-1 integrase inhibitors.

    PubMed

    Toropova, Alla P; Toropov, Andrey A; Benfenati, Emilio; Gini, Giuseppina

    2011-05-01

    The simplified molecular input-line entry system (SMILES) and IUPAC International Chemical Identifier (InChI) were examined as representations of the molecular structure for quantitative structure-activity relationships (QSAR), which can be used to predict the inhibitory activity of styrylquinoline derivatives against the human immunodeficiency virus type 1 (HIV-1). Optimal SMILES-based descriptors give a best model with n = 26, r(2) = 0.6330, q(2) = 0.5812, s = 0.502, F = 41 for the training set and n = 10, r(2) = 0.7493, r(pred)(2) = 0.6235, R(m)(2) = 0.537, s = 0.541, F = 24 for the validation set. Optimal InChI-based descriptors give a best model with n = 26, r(2) = 0.8673, q(2) = 0.8456, s = 0.302, F = 157 for the training set and n = 10, r(2) = 0.8562, r(pred)(2) = 0.7715, R(m)(2) = 0.819, s = 0.329, F = 48 for the validation set. Thus, the InChI-based model is preferable. The described SMILES-based and InChI-based approaches have been checked with five random splits into the training and test sets. PMID:21352501

  9. HL271, a novel chemical compound derived from metformin, differs from metformin in its effects on the circadian clock and metabolism.

    PubMed

    Row, Hansang; Jeong, Jaekap; Cho, Sehyung; Kim, Sungwuk; Kim, Kyungjin

    2016-01-15

    Metformin is a treatment of choice for patients with type 2 diabetes. Its action involves the phosphorylation of 5'-adenosine monophosphate activated protein kinase (AMPK), leading to inhibition of liver gluconeogenesis. The effects of a novel chemical compound derived from metformin, HL271, on molecular and physiological actions involving AMPK and rhythmically-expressed circadian clock genes were investigated. HL271 potently activated AMPK in a dose-dependent manner, and produced shortening of the circadian period and enhanced degradation of the clock genes PER2 and CRY1. Although the molecular effects of HL271 resembled those of metformin, it produced different physiological effects in mice with diet-induced obesity. HL271 did not elicit glucose-lowering or insulin-sensitizing effects, possibly because of altered regulation of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase 1. This indicated that, although HL271 acted on circadian clock machinery through a similar molecular mechanism to metformin, it differed in its systemic effect on glucose and lipid metabolite regulations. PMID:26707879

  10. Stabilization of asphaltenes in aliphatic solvents using alkylbenzene-derived amphiphiles. 1. Effect of the chemical structure of amphiphiles on asphaltene stabilization

    SciTech Connect

    Chang, C.L.; Fogler, H.S. )

    1994-06-01

    Stabilization of crude oil asphaltenes in apolar alkane solvents was investigated using a series of alkylbenzene-derived amphiphiles as the asphaltene stabilizers. In this paper (i.e., part I), we present the study on the influences of the chemical structure of these amphiphiles on the effectiveness of asphaltene solubilization and on the strength of asphaltene-amphiphile interaction using both UV/vis and FTIR spectroscopies. The results showed that the amphiphile's effectiveness of asphaltene stabilization was primarily controlled by the polarity of the amphiphile's head group and the length of the amphiphile's alkyl tail. Increasing the acidity of the amphiphile's head group could promote the amphiphile's ability to stabilize asphaltenes by increasing the acid-base attraction between asphaltenes and amphiphiles. On the other hand, although decreasing the amphiphile's tail length increased the asphaltene-amphiphile attraction slightly, it still required a minimum tail length (six carbons for p-alkylphenol amphiphiles) for amphiphiles to form stable steric layers around asphaltenes. We also found additional acidic side groups of amphiphiles could further improve the amphiphile's ability to stabilize asphaltenes. The effect of the molecular weight of alkane solvents on the amphiphile's ability to stabilize asphaltenes was also studied. 18 refs., 12 figs., 3 tabs.

  11. VITAL NMR: Using Chemical Shift Derived Secondary Structure Information for a Limited Set of Amino Acids to Assess Homology Model Accuracy

    SciTech Connect

    Brothers, Michael C; Nesbitt, Anna E; Hallock, Michael J; Rupasinghe, Sanjeewa; Tang, Ming; Harris, Jason B; Baudry, Jerome Y; Schuler, Mary A; Rienstra, Chad M

    2011-01-01

    Homology modeling is a powerful tool for predicting protein structures, whose success depends on obtaining a reasonable alignment between a given structural template and the protein sequence being analyzed. In order to leverage greater predictive power for proteins with few structural templates, we have developed a method to rank homology models based upon their compliance to secondary structure derived from experimental solid-state NMR (SSNMR) data. Such data is obtainable in a rapid manner by simple SSNMR experiments (e.g., (13)C-(13)C 2D correlation spectra). To test our homology model scoring procedure for various amino acid labeling schemes, we generated a library of 7,474 homology models for 22 protein targets culled from the TALOS+/SPARTA+ training set of protein structures. Using subsets of amino acids that are plausibly assigned by SSNMR, we discovered that pairs of the residues Val, Ile, Thr, Ala and Leu (VITAL) emulate an ideal dataset where all residues are site specifically assigned. Scoring the models with a predicted VITAL site-specific dataset and calculating secondary structure with the Chemical Shift Index resulted in a Pearson correlation coefficient (-0.75) commensurate to the control (-0.77), where secondary structure was scored site specifically for all amino acids (ALL 20) using STRIDE. This method promises to accelerate structure procurement by SSNMR for proteins with unknown folds through guiding the selection of remotely homologous protein templates and assessing model quality.

  12. Influence of the fullerene derivatives and cage polyhedral oligomeric silsesqiuoxanes on 3-aminopropyltrimethoxysilane based hybrid nanocomposites chemical, morphological and electrical properties

    NASA Astrophysics Data System (ADS)

    Klocek, Jolanta; Kolanek, Krzysztof; Henkel, Karsten; Zschech, Ehrenfried; Schmeisser, Dieter

    2013-01-01

    In this study we produced 3-aminopropyltrimethoxysilane based hybrid nanocomposites using fullerene derivative [6,6]?phenyl?C61?butyric acid methyl ester (PCBM) as nanodopants. Additionally, we modified obtained material with incompletely condensed cage polyhedral oligomeric silsesqiuoxanes (POSS) in order to improve its properties. Thin films were deposited by means of the spin-coating method. The films were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and capacitance-voltage (CV) measurements. We observed that a properly chosen PCBM concentration may be a crucial factor to obtain high quality APTMS based films by the spin-coating technique. XPS revealed the presence of the C-NH-C species within POSS containing films indicating chemical interaction between the amino group of APTMS and the POSS molecules. AFM results suggest that at high POSS monomer concentration in the range of 1% the creation of fractal-shaped aggregates takes place. The CV characterization of the samples exhibits a decrease of the APTMS based films dielectric constant due to the POSS and PCBM contribution. The combination of the applied methods delivers complementary information concerning the properties of the analyzed films.

  13. Adding liraglutide to the backbone therapy of biguanide in patients with coronary artery disease and newly diagnosed type-2 diabetes (the AddHope2 study): a randomised controlled study protocol

    PubMed Central

    Anholm, Christian; Kumarathurai, Preman; Klit, Malene S; Kristiansen, Ole P; Nielsen, Olav W; Ladelund, Steen; Madsbad, Sten; Sajadieh, Ahmad; Haugaard, Steen B

    2014-01-01

    Introduction Newly diagnosed type 2 diabetes mellitus (T2DM) in patients with coronary artery disease (CAD) more than doubles the risk of death compared with otherwise matched glucose tolerant patients. The biguanide metformin is the drug of choice in treatment of T2DM and has shown to ameliorate cardiovascular morbidity in patients with T2DM and myocardial infarction (MI). The incretin hormone, glucagon-like peptide-1 (GLP-1) improves ?-cell function, insulin sensitivity and causes weight loss and has been suggested to have beneficial effects on cardiac function. The GLP-1 receptor agonist (GLP-1RA), liraglutide, is currently used for treatment of T2DM but its potential effect on cardiac function has not been investigated in detail. We hypothesised that liraglutide added to metformin backbone therapy in patients with CAD and newly diagnosed T2DM will improve ?-cell function and left ventricular systolic function during dobutamine stress. Methods and analyses 40 patients with CAD and newly diagnosed T2DM will receive the intervention liraglutide+metformin and placebo+metformin in this investigator-initiated, double blind, randomised, placebo-controlled, cross-over 12 plus 12?weeks intervention study with a 2-week washout period. The primary cardiovascular end point is changes in left ventricular ejection fraction during stress echocardiography. The primary endocrine end point is ?-cell function evaluated during a frequently sampled intravenous glucose tolerance test. Secondary end points include heart rate variability, diurnal blood pressure, glucagon suppression and inflammatory response (urine, blood and adipose tissue). Ethics and dissemination This study is approved by the Danish Medicines Agency, the Danish Dataprotection Agency and the Regional Committee on Biomedical Research Ethics of the Capital Region of Denmark. The trial will be carried out under the guidance from the GCP unit at Copenhagen University Hospital of Bispebjerg and in accordance with the ICH-GCP guidelines and the Helsinki Declaration. Trial registrations number Clinicaltrials.gov ID: NCT01595789, EudraCT: 2011-005405-78. PMID:25031198

  14. Chemical and genetic blockade of HDACs enhances osteogenic differentiation of human adipose tissue-derived stem cells by oppositely affecting osteogenic and adipogenic transcription factors

    SciTech Connect

    Maroni, Paola; Brini, Anna Teresa; Dipartimento di Scienze Biomediche, Chirurgiche ed Odontoiatriche, Universita degli Studi di Milano, Milano ; Arrigoni, Elena; Girolamo, Laura de; Niada, Stefania; Dipartimento di Scienze Biomediche, Chirurgiche ed Odontoiatriche, Universita degli Studi di Milano, Milano ; Matteucci, Emanuela; Bendinelli, Paola; Desiderio, Maria Alfonsina

    2012-11-16

    Highlights: Black-Right-Pointing-Pointer Acetylation affected hASCs osteodifferentiation through Runx2-PPAR{gamma}. Black-Right-Pointing-Pointer HDACs knocking-down favoured the commitment effect of osteogenic medium. Black-Right-Pointing-Pointer HDACs silencing early activated Runx2 and ALP. Black-Right-Pointing-Pointer PPAR{gamma} reduction and calcium/collagen deposition occurred later. Black-Right-Pointing-Pointer Runx2/PPAR{gamma} target genes were modulated in line with HDACs role in osteo-commitment. -- Abstract: The human adipose-tissue derived stem/stromal cells (hASCs) are an interesting source for bone-tissue engineering applications. Our aim was to clarify in hASCs the role of acetylation in the control of Runt-related transcription factor 2 (Runx2) and Peroxisome proliferator activated receptor (PPAR) {gamma}. These key osteogenic and adipogenic transcription factors are oppositely involved in osteo-differentiation. The hASCs, committed or not towards bone lineage with osteoinductive medium, were exposed to HDACs chemical blockade with Trichostatin A (TSA) or were genetically silenced for HDACs. Alkaline phosphatase (ALP) and collagen/calcium deposition, considered as early and late osteogenic markers, were evaluated concomitantly as index of osteo-differentiation. TSA pretreatment, useful experimental protocol to analyse pan-HDAC-chemical inhibition, and switch to osteogenic medium induced early-osteoblast maturation gene Runx2, while transiently decreased PPAR{gamma} and scarcely affected late-differentiation markers. Time-dependent effects were observed after knocking-down of HDAC1 and 3: Runx2 and ALP underwent early activation, followed by late-osteogenic markers increase and by PPAR{gamma}/ALP activity diminutions mostly after HDAC3 silencing. HDAC1 and 3 genetic blockade increased and decreased Runx2 and PPAR{gamma} target genes, respectively. Noteworthy, HDACs knocking-down favoured the commitment effect of osteogenic medium. Our results reveal a role for HDACs in orchestrating osteo-differentiation of hASCs at transcriptional level, and might provide new insights into the modulation of hASCs-based regenerative therapy.

  15. Predicting biological effects of environmental mixtures using exposure:activity ratios (EAR) derived from US EPA’s ToxCast data: Retrospective application to chemical monitoring data

    EPA Science Inventory

    Chemical monitoring has been widely used in environmental surveillance to assess exposure to environmental contaminants which could represent potential hazards to exposed organisms. However, the ability to detect chemicals in the environment has rapidly outpaced assessment of pot...

  16. Predicting biological effects of environmental mixtures using exposure:activity ratios (EAR) derived from US EPAs ToxCast data: Retrospective application to chemical monitoring data

    EPA Science Inventory

    Chemical monitoring has been widely used in environmental surveillance to assess exposure to environmental contaminants which could represent potential hazards to exposed organisms. However, the ability to detect chemicals in the environment has rapidly outpaced assessment of pot...

  17. The effect of alterations in physical and chemical characteristics on TOBEC-derived body composition estimates: validation with non-human models.

    PubMed

    De Bruin, N C; Luijendijk, I H; Visser, H K; Degenhart, H J

    1994-07-01

    The measurement of total-body electrical conductivity (TOBEC) has become one of the standard methods for the estimation of body composition in infants. We investigated, using non-human models, the effect on the accuracy of TOBEC-derived body composition estimates of alterations in physical and chemical characteristics of the fat-free mass (FFM). The effect of electrolyte type, concentration and volume on TOBEC was determined using 2, 3 and 51 solutions of six different chlorides and sodium bicarbonate. Equimolar concentrations yielded TOBEC values in accordance with known ion conductivities: H+ > Ca2+ > Mg2+ > K+ > Na+ > Li+ and Cl- > HCO3-. The behaviour of these solutions was described very accurately over a wide range of concentrations (1-200 mM) by a simple exponential law. Dissolved egg-white protein, glycine and L-glutamine elicited no TOBEC signal. In vitro, using polyethylene bottles filled with physiologic saline, in the interval of 2-45 degrees C a linear relation was observed between temperature and TOBEC. Below the freezing point no TOBEC signal was elicited. The effect of tissue autolysis and body temperature on TOBEC was examined by repeated measurements of TOBEC and temperature in seven fresh infant minipig cadavers. Five minipigs were allowed to cool. Shortly after death TOBEC decreased by 2.5% per degrees C. Two animals were kept at constant temperature. The TOBEC signal showed a gradual increase of 9% after 7 h due to autolysis. We conclude that in vivo TOBEC measurements are affected by ion concentration (e.g. non-isotonic hydration changes), geometry (e.g. deviations in body shape), temperature (e.g. fever, skin cooling) and tissue autolysis (measurements after death). Proteins, molecules with strong dipole moments and ions trapped in crystalline structures do not significantly affect the TOBEC reading. PMID:15552103

  18. Constraints on the Origins of Along-Arc and Cross-Arc Chemical Variations in Arc Volcanic systems Derived from Global Systematics of Fluid-Mobile Elements

    NASA Astrophysics Data System (ADS)

    Ryan, Jeffrey

    2014-05-01

    The fluid-mobile element (FME) "clan" (B, Cs, As, Sb; conditionally Pb, Rb, Ba, Li, N, I: Leeman 1996; Noll et al 1996; Bebout et al 1999; Savov et al 2005) comprises a chemically disparate suite of trace elements that have in common evidence for low T°/low P mobility from subducting materials in H2O-dominated fluid species. The FME are highly variable in volcanic arc lavas, showing marked along-arc and across arc changes in nearly all of the arc volcanic systems that have been examined. Globally, along-arc variability of the FME can be explained as source mixing, with most arcs defining arrays between two predominant sources: the first a strongly FME-enriched endmember, showing enrichment patterns consistent with those observed in subduction-related serpentinites (Savov et al 2005; Hattori and Guillot 2007), and the second an FME-poor source with signatures for other large-ion lithophile elements (LIL) consistent with subducted slab (predominantly subducted sediment) derivation. The mantle is a negligible contributor to FME systematics in those arcs where the inferred thermal structures are cool at relatively shallow (30-40 km) depths (e.g., Syracuse, et al 2011). However, in the relatively few arcs that show hotter thermal structures at shallow depths, the FME-enriched component is absent, and the mixing components are the mantle and the FME-poor, LIL enriched component observed in all arcs. Regular across-arc declines in enrichments of boron and other FME are a diagnostic feature in volcanic arcs globally. B abundance and isotope systematics for across-arc transects point to a) anomalously high B and B isotope signals near the volcanic front, often some of the highest signatures in the arc, suggesting locally higher inputs of the FME-enriched endmember to mantle sources at that point along the volcanic front. These enrichments, as well as the positioning of the widest volcanic cross-chains, are often linked to physical phenomena (seamount or fracture zone subduction, or faults or grabens perpendicular to the strike of the arc). b) Along cross-arc arrays, there is FME evidence for three-component mixing, involving the two slab-derived FME components and the mantle, in which the FME-depleted slab endmember plays a greater role as subduction depths increase. In general, the overriding arc crust plays a minor role in the FME systematics of arcs, though in those cases where the crustal section is thick and slab-derived signatures are modest, the crustal contribution helps define a baseline level for FME abundance and isotopic signatures throughout the arc. References: Bebout, et al 1999, EPSL 177, 69; Hattori and Guillot, 2007, GCubed, http://dx.doi.org/10.1029/2007GC001594; Leeman. 1996, AGU Monograph 96, 269; Noll et al, 1996, GCA 60, 587; Savov et al, 2005; GCubed, Q04J15 DOI10.1029/2004GC000777; Syracuse et al. 2011, GCubed, http://dx.doi.org/10.1029/2005GC001045.

  19. Influence of oxide impurities on the chemical tuning of the thermoelectric properties of substitution derivatives of RuIn{sub 3}

    SciTech Connect

    Wagner-Reetz, Maik Cardoso-Gil, Raul; Schmidt, Marcus; Grin, Yuri

    2014-07-01

    A systematic investigation on tuning the charge carrier concentration by substitution of the Ru position in RuIn{sub 3} is performed. Samples with nominal composition Ru{sub 0.95}T{sub 0.05}In{sub 3} (T=Re, Rh, Ir) were synthesized via liquidsolid-reaction and subsequent spark plasma sintering treatment. The chemical composition was characterized by X-ray, metallographic and microstructure analysis revealing solid solutions in the samples with Rh and Ir, whereas Re cannot be incorporated in RuIn{sub 3}. Minor oxide impurities in the commercially available starting elements, the homogeneity range of RuIn{sub 3} and the redox potentials of the participating elements are the key for interpreting the observed lattice parameters and the corresponding composition. Both, substitutions with Rh or Ir and Re inclusions in RuIn{sub 3} lead independently to a significant decrease of the total thermal conductivity down to approximately one half of the value observed for binary RuIn{sub 3}, prepared with commercially available starting materials. The electrical resistivity was reduced by substitution and the temperature dependence changes from semiconductor-like, for RuIn{sub 3}, to metal-like in the substitution derivatives. At the same time the sign change in the thermopower at high temperatures, characteristic for binary RuIn{sub 3}, is suppressed, attaining only electrons as majority carriers. - Graphical abstract: Microstructure (perpendicular to the pressure axis; polarized light) of polycrystalline Ru{sub 0.95}Rh{sub 0.05}In{sub 3} (a), Ru{sub 0.95}Ir{sub 0.05}In{sub 3} (b) and Ru{sub 0.95}Re{sub 0.05}In{sub 3} (c) samples after SPS treatment. - Highlights: Substitution solid solutions of RuIn{sub 3} were prepared via liquidsolid-reaction. Chemistry of oxide impurities is crucial for explanation of experimental results. Thermodynamic calculations support the observation of In{sub 2}O{sub 3} or ZnO as impurities. Electrical resistivity is reduced by substitution. Temperature dependence of resistivity changes from semiconductor- to metal-like.

  20. Substituent effect study on experimental ¹³C NMR chemical shifts of (3-(substituted phenyl)-cis-4,5-dihydroisoxazole-4,5-diyl)bis(methylene)diacetate derivatives.

    PubMed

    Kara, Yesim S

    2015-12-01

    Eleven novel (3-(substituted phenyl)-cis-4,5-dihydroisoxazole-4,5-diyl)bis(methylene) diacetate derivatives were synthesized in the present study. These dihydroisoxazole derivatives were characterized by IR, (1)H NMR, (13)C NMR and elemental analyses. Their (13)C NMR spectra were measured in Deuterochloroform (CDCl3). The correlation analysis for the substituent-induced chemical shift (SCS) with Hammett substituent constant (σ), inductive substituent constant (σI), different of resonance substituent constants (σR, σR(o)) and Swain-Lupton substituent parameters (F, R) were performed using SSP (single substituent parameter), and DSP (dual substituent parameter) methods, as well as single and multiple regression analysis. From the result of regression analysis, the effect of substituent on the (13)C NMR chemical shifts was explained. PMID:26172459

  1. Synthesis and reactions of a nucleoside derivative of phosphoric sulfonic anhydride. Studies related to the mechanisms of coupling reactions in the chemical synthesis of oligodeoxyribonucleotides by phosphotriester procedures.

    PubMed Central

    Dabkowski, W; Skrzypczynski, Z; Michalski, J; Piel, N; McLaughlin, L W; Cramer, F

    1984-01-01

    The synthesis of a model compound, diphenylphosphoric toluene-p-sulfonic anhydride, an arylsubstituted phosphoric sulfonic mixed anhydride, is described. Using the same procedure a thymidyl substituted derivative was prepared. The phosphoric sulfonic anhydride is the presumed intermediate in oligonucleotide coupling reactions involving phosphodiester activation by arenesulfonyl derivatives. This mixed anhydride reacts with a variety of nucleophiles. It can be converted to phophotriester derivatives in the presence of simple alcohols. Phosphotriester formation using the 5'-hydroxyl of a thymidine derivative requires additionally a catalyst such as N-methylimidazole. The reactive intermediate produced upon the addition of N-methylimidazole to the phosphoric sulfonic anhydride has been observed spectroscopically using 31P-NMR. PMID:6549065

  2. Metabolomics based on liquid chromatography with mass spectrometry reveals the chemical difference in the stems and roots derived from Ephedra sinica.

    PubMed

    Lv, Mengying; Chen, Jiaqing; Gao, Yiqiao; Sun, Jianbo; Zhang, Qianqian; Zhang, Mohan; Xu, Fengguo; Zhang, Zunjian

    2015-10-01

    To better understand different traditional uses of the stems (known as Mahuang) and roots (known as Mahuanggen) of Ephedra sinica, their chemical difference should be investigated. In this study, an ultra-fast liquid chromatography coupled with ion trap time-of-flight mass spectrometry untargeted metabolomics approach was established to reveal global chemical difference between Mahuang and Mahuanggen. Clear separation was observed in scores plots of principal component analysis and orthogonal partial least squares-discriminant analysis. Twenty two chemical markers responsible for such separation were screened out and unambiguously/tentatively characterized. Then chemical markers of pharmacologically important ephedrine and pseudoephedrine were absolutely quantified using liquid chromatography coupled with tandem mass spectrometry under multiple reaction monitoring mode. The results showed that Mahuang was rich in ephedrine-type alkaloids, while Mahuanggen was rich in macrocyclic spermine alkaloids. Additionally, different types of flavan-3-ols and flavones exist in Mahuang and Mahuanggen extracts. This research facilitates a better understanding of different traditional uses of Mahuang and Mahuanggen and provides references for chemical analysis of other medicinal plants. PMID:26224607

  3. Synthesis, spectral analysis, X-ray crystal structures and evaluation of chemical reactivity of five new benzoindazole derivatives through experimental and theoretical studies

    NASA Astrophysics Data System (ADS)

    Taib, Layla A.; Faidallah, Hassan M.; ?ahin, Zarife Sibel; Asiri, Abdullah M.; ?ahin, Onur; Arshad, Muhammad Nadeem

    2014-11-01

    The main purpose of this study was synthesis, X-ray, DFT and spectroscopic investigations of the title compounds (I-V). Five new compounds were synthesized and the detailed experimental results are reported. The crystal and molecular structures of the title compounds have been determined by IR, 1H NMR, 13C NMR and single-crystal X-ray diffraction. Molecular geometries from X-ray experiment of I-V in the ground state have been compared using the Density Functional Theory (DFT) with B3LYP/6-31G(d,p) basis set. In addition, the molecular electrostatic potential maps and frontier molecular orbitals were performed at B3LYP/6-31G(d,p) level of theory. DFT global chemical reactivity descriptors (chemical hardness, total energy, electronic chemical potential and electrophilicity) are calculated for the title molecules and used to predict their relative stability and reactivity.

  4. Optical fiber chemical sensors with sol-gel derived nanomaterials for monitoring high temperature/high pressure reactions in clean energy technologies

    NASA Astrophysics Data System (ADS)

    Tao, Shiquan

    2010-04-01

    The development of sensor technologies for in situ, real time monitoring the high temperature/high pressure (HTP) chemical processes used in clean energy technologies is a tough challenge, due to the HTP, high dust and corrosive chemical environment of the reaction systems. A silica optical fiber is corrosive resistance, and can work in HTP conditions. This paper presents our effort in developing fiber optic sensors for in situ, real time monitoring the concentration of trace ammonia and hydrogen in high temperature gas samples. Preliminary test results illustrate the feasibility of using fiber optic sensor technologies for monitoring HTP processes for next generation energy industry.

  5. Assessment of the Ecological Risks of Endocrine-Disrupting Chemicals (EDCs): Derivation of WQC and Consideration of Concentrated Animal Feeding Operations as a Source

    EPA Science Inventory

    The occurrence of endocrine-disrupting chemicals (EDCs) in the environment has been associated with impacts on fish. Hence, there is a need for numerical water quality criteria (WQC) for the protection of aquatic life from adverse effects of EDCs. However, EDCs have some unique...

  6. The anisotropic effect of functional groups in 1H NMR spectra is the molecular response property of spatial nucleus independent chemical shifts (NICS)--conformational equilibria of exo/endo tetrahydrodicyclopentadiene derivatives.

    PubMed

    Kleinpeter, Erich; Lmmermann, Anica; Khn, Heiner

    2011-02-21

    The inversion of the flexible five-membered ring in tetrahydrodicyclopentadiene (TH-DCPD) derivatives remains fast on the NMR timescale even at 103 K. Since the intramolecular exchange process could not be sufficiently slowed for spectroscopic evaluation, the conformational equilibrium is thus inaccessible by dynamic NMR. Fortunately, the spatial magnetic properties of the aryl and carbonyl groups attached to the DCPD skeleton can be employed in order to evaluate the conformational state of the system. In this context, the anisotropic effects of the functional groups in the (1)H NMR spectra prove to be the molecular response property of spatial nucleus independent chemical shifts (NICS). PMID:21152640

  7. Optical poling effect and optical absorption of cyan, ethylcarboxyl and tert -buthyl derivatives of 1H-pyrazolo[3,4-b]quinoline: experiment and quantum-chemical simulations

    NASA Astrophysics Data System (ADS)

    Ko?cie?, E.; Sanetra, J.; Gondek, E.; Jarosz, B.; Kityk, I. V.; Ebothe, J.; Kityk, A. V.

    2005-06-01

    We present here results of experimental studies and quantum-chemical simulations of optical absorption and optical poling effects performed on a new synthesized cyan, ethylcarboxyl and tert -buthyl derivatives of 1H-pyrazolo[3,4-b]quinoline incorporated into polymer matrix or dissolved in organic solutions. The efficiency of second-order optical susceptibility d vs photoinduced power density I clearly saturates to certain magnitude d at sufficient power densities ( I? 1.3 GW cm -2). Comparing experimental data and results of semiempirical quantum-chemical simulations one can conclude that there exists generally a good correlation between the magnitude of saturated susceptibilities d and macroscopic hyperpolarizabilities for all compounds except the chromophore 1,3-dimethyl-6-cyano-[PQ] only. The discrepancy for this compound may reflect a specific contribution of surrounding polymer matrix. According to the quantum chemical analysis the methyl-containing cyan and ethylocarcoxyl derivatives reveal four/five strong absorption bands in the spectral range 200-500 nm. A substitution of the methyl groups by the phenyl group causes the substantial changes of the absorption spectra mainly in the spectral range 240-370 nm. Measured and calculated absorption spectra manifest rather good agreement mainly in the part regarding the spectral positions of the first oscillator (absorption threshold). The quantum-chemical PM3 method shows the best agreement with experiment. At the same time a considerable broadening almost of all absorption bands appears as a characteristic feature of all measured spectra. The discrepancies between the calculated and the measured spectra are attributed to electron-vibronic coupling as well as to a specific rotational dynamics of phenyl rings.

  8. Some Phthalocyanine and Naphthalocyanine Derivatives as Corrosion Inhibitors for Aluminium in Acidic Medium: Experimental, Quantum Chemical Calculations, QSAR Studies and Synergistic Effect of Iodide Ions.

    PubMed

    Dibetsoe, Masego; Olasunkanmi, Lukman O; Fayemi, Omolola E; Yesudass, Sasikumar; Ramaganthan, Baskar; Bahadur, Indra; Adekunle, Abolanle S; Kabanda, Mwadham M; Ebenso, Eno E

    2015-01-01

    The effects of seven macrocyclic compounds comprising four phthalocyanines (Pcs) namely 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (Pc1), 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (Pc2), 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (Pc3) and 29H,31H-phthalocyanine (Pc4), and three naphthalocyanines namely 5,9,14,18,23,27,32,36-octabutoxy-2,3-naphthalocyanine (nPc1), 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (nPc2) and 2,3-naphthalocyanine (nP3) were investigated on the corrosion of aluminium (Al) in 1 M HCl using a gravimetric method, potentiodynamic polarization technique, quantum chemical calculations and quantitative structure activity relationship (QSAR). Synergistic effects of KI on the corrosion inhibition properties of the compounds were also investigated. All the studied compounds showed appreciable inhibition efficiencies, which decrease with increasing temperature from 30 °C to 70 °C. At each concentration of the inhibitor, addition of 0.1% KI increased the inhibition efficiency compared to the absence of KI indicating the occurrence of synergistic interactions between the studied molecules and I(-) ions. From the potentiodynamic polarization studies, the studied Pcs and nPcs are mixed type corrosion inhibitors both without and with addition of KI. The adsorption of the studied molecules on Al surface obeys the Langmuir adsorption isotherm, while the thermodynamic and kinetic parameters revealed that the adsorption of the studied compounds on Al surface is spontaneous and involves competitive physisorption and chemisorption mechanisms. The experimental results revealed the aggregated interactions between the inhibitor molecules and the results further indicated that the peripheral groups on the compounds affect these interactions. The calculated quantum chemical parameters and the QSAR results revealed the possibility of strong interactions between the studied inhibitors and metal surface. QSAR analysis on the quantum chemical parameters obtained with B3LYP/6-31G (d,p) method show that a combination of two quantum chemical parameters to form a composite index provides the best correlation with the experimental data. PMID:26343626

  9. Aggregation-induced emissions of tetraphenylethene derivatives and their utilities as chemical vapor sensors and in organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Dong, Yongqiang; Lam, Jacky W. Y.; Qin, Anjun; Liu, Jianzhao; Li, Zhen; Tang, Ben Zhong; Sun, Jiaxin; Kwok, Hoi Sing

    2007-07-01

    Nonemissive tetraphenylethene (TPE) 1 and its diphenylated derivative 2 were induced to emit intensely by aggregate formation. Crystalline aggregates of the dyes emitted bluer lights than their amorphous counterparts. The emissions of the TPE dyes could be switched off and on continuously and reversibly by wetting and dewetting with solvent vapors, respectively, manifesting their ability to optically sense volatile organic compounds. The light-emitting diodes fabricated from 1 and 2 were turned on at 2.9 and 5V and emitted blue lights with maximum luminance of 1800 and 11000cd/m2, respectively.

  10. A three-dimensional chemical phase pharmacophore mapping, QSAR modelling and electronic feature analysis of benzofuran salicylic acid derivatives as LYP inhibitors.

    PubMed

    Suryanarayanan, V; Singh, S Kumar; Tripathi, S Kumar; Selvaraj, C; Reddy, K Konda; Karthiga, A

    2013-01-01

    Lymphoid tyrosine phosphatase (LYP), encoded by the PTPN22 gene, has a critical negative regulatory role in T-cell antigen receptor (TCR) and emerged as a promising drug target for human autoimmune diseases. A five-point pharmacophore with two hydrogen bond acceptors, one hydrogen bond donor and two aromatic ring features was generated for a series of benzofuran salicylic acid derivatives as LYP inhibitors in order to elucidate their anti-autoimmune activity. The generated pharmacophore yielded a significant 3D-QSAR model with r(2) of 0.9146 for a training set of 27 compounds. The model also showed excellent predictive power with Q(2) of 0.7068 for a test set of eight compounds. The investigation of the 3D-QSAR model has revealed the structural insights which could lead to more potent analogues. The most active and inactive compounds were further subjected to electronic structure analysis using density functional theory (DFT) at B3LYP/3-21(?)G level to support the 3D-QSAR predictions. The results obtained from this study are expected to be useful in the proficient design and development of benzofuran salicylic acid derivatives as inhibitors of LYP. PMID:23987088

  11. Identification of UV-protective Activators of Nuclear Factor Erythroid-derived 2-Related Factor 2 (Nrf2) by Combining a Chemical Library Screen with Computer-based Virtual Screening*

    PubMed Central

    Lieder, Franziska; Reisen, Felix; Geppert, Tim; Sollberger, Gabriel; Beer, Hans-Dietmar; auf dem Keller, Ulrich; Schfer, Matthias; Detmar, Michael; Schneider, Gisbert; Werner, Sabine

    2012-01-01

    Nuclear factor erythroid-derived 2-related factor 2 (Nrf2) is a master regulator of cellular antioxidant defense systems, and activation of this transcription factor is a promising strategy for protection of skin and other organs from environmental insults. To identify efficient Nrf2 activators in keratinocytes, we combined a chemical library screen with computer-based virtual screening. Among 14 novel Nrf2 activators, the most potent compound, a nitrophenyl derivative of 2-chloro-5-nitro-N-phenyl-benzamide, was characterized with regard to its molecular mechanism of action. This compound induced the expression of cytoprotective genes in keratinocytes isolated from wild-type but not from Nrf2-deficient mice. Most importantly, it showed low toxicity and protected primary human keratinocytes from UVB-induced cell death. Therefore, it represents a potential lead compound for the development of drugs for skin protection under stress conditions. Our study demonstrates that chemical library screening combined with advanced computational similarity searching is a powerful strategy for identification of bioactive compounds, and it points toward an innovative therapeutic approach against UVB-induced skin damage. PMID:22851183

  12. Identification of UV-protective activators of nuclear factor erythroid-derived 2-related factor 2 (Nrf2) by combining a chemical library screen with computer-based virtual screening.

    PubMed

    Lieder, Franziska; Reisen, Felix; Geppert, Tim; Sollberger, Gabriel; Beer, Hans-Dietmar; auf dem Keller, Ulrich; Schfer, Matthias; Detmar, Michael; Schneider, Gisbert; Werner, Sabine

    2012-09-21

    Nuclear factor erythroid-derived 2-related factor 2 (Nrf2) is a master regulator of cellular antioxidant defense systems, and activation of this transcription factor is a promising strategy for protection of skin and other organs from environmental insults. To identify efficient Nrf2 activators in keratinocytes, we combined a chemical library screen with computer-based virtual screening. Among 14 novel Nrf2 activators, the most potent compound, a nitrophenyl derivative of 2-chloro-5-nitro-N-phenyl-benzamide, was characterized with regard to its molecular mechanism of action. This compound induced the expression of cytoprotective genes in keratinocytes isolated from wild-type but not from Nrf2-deficient mice. Most importantly, it showed low toxicity and protected primary human keratinocytes from UVB-induced cell death. Therefore, it represents a potential lead compound for the development of drugs for skin protection under stress conditions. Our study demonstrates that chemical library screening combined with advanced computational similarity searching is a powerful strategy for identification of bioactive compounds, and it points toward an innovative therapeutic approach against UVB-induced skin damage. PMID:22851183

  13. Identification of dredged sediment-derived soils in the alluvial plains of the Leie and the Upper and Sea Scheldt rivers (Belgium) based on physico-chemical soil properties.

    PubMed

    Vandecasteele, Bart; De Vos, Bruno; Tack, Filip M G

    2002-04-01

    An approach was developed to identify surface soils affected by historical dredged sediment disposal in the alluvial plains of the Upper Scheldt, the Sea Scheldt and the Leie river. Dredged sediment-derived soils were identified based on field observations, comparative granulometric analyses and chemical analyses. Criteria developed were based on a comparison between reference data from 102 aerobic soil samples of areas known to be affected by dredged sediment disposal and 104 samples from undisturbed alluvial soils along the studied rivers. A comparative grain size analysis with optical laser diffractometry between the A and C horizon proved useful for the identification of levelled-up sites. The chemical soil characteristics that were most useful in identifying dredged sediment-derived soils were CaCO3, sulfur (S), organic carbon (OC) and phosphorus (P) contents, electrical conductivity (EC), and the C/P and C/S ratios. Criteria for concluding the origin of an investigated soil were specific for the studied area, but the approach presented may provide useful guidelines for developing criteria valid for different regions. PMID:11993775

  14. Effect of interface structure on the chemical composition and electrical properties of sol-gel-derived LaNiO3 films

    NASA Astrophysics Data System (ADS)

    Zhu, M. W.; Wang, H. L.; Han, H. J.; Wang, Z. J.; Zhang, Z. D.

    2015-06-01

    In the present work, lanthanum nickel oxide (LNO) thin films are prepared with the sol-gel multilayer coating method. Lattice-matched SrTiO3 (STO) buffer layer is introduced to tailor the film-substrate interface. The effect of interface structure on the electrical properties, microstructure and chemical composition of LNO films is investigated. The results show that the improvement in the interface structure minimizes the effect of interface on the electrical properties of LNO films and leads to a sharp decrease in room-temperature resistivity of LNO films to 570 ?? cm, comparable to that of the LNO films on single-crystal STO substrate. This is ascribed to the decrease in structural disorder and the concentration of oxygen vacancies in the LNO films.

  15. Analysis of Phenacylester Derivatives of Fatty Acids from Human Skin Surface Sebum by Reversed-Phase HPLC: Chromatographic Mobility as a Function of Physico-Chemical Properties

    PubMed Central

    Bodoprost, Juliana; Rosemeyer, Helmut

    2007-01-01

    A set of 13 fatty acids was transformed into their phenacyl esters by reaction with phenacyl bromide in acetonitrile using 18-crown-6 as phase-transfer catalyst. Conditions for the RP-18 HPL chromatographic separation of most of the esters has been worked out. Using this standard the fatty acid spectra from skin surface sebum lipids of 17 test persons was taken after microwave-assisted hydrolysis, neutralization and extraction with n-hexane. Quantitative evaluation of the chromatograms exhibits that oleic acid predominates in the sebum of all test persons. In the second part of the work the chromatographic mobility (RE values) of fatty acid phenacyl esters is correlated with calculated physico-chemical parameters of the corresponding acids. The best linear correlation was found between the RE and the logP values. This is helpful for the structural elucidation of un-identified fatty acids in a chromatogram.

  16. Study on the fate of petroleum-derived polycyclic aromatic hydrocarbons (PAHs) and the effect of chemical dispersant using an enclosed ecosystem, mesocosm.

    PubMed

    Yamada, Mihoko; Takada, Hideshige; Toyoda, Keita; Yoshida, Akihiro; Shibata, Akira; Nomura, Hideaki; Wada, Minoru; Nishimura, Masahiko; Okamoto, Ken; Ohwada, Kouichi

    2003-01-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are one of the components found in oil and are of interest because some are toxic. We studied the environmental fate of PAHs and the effects of chemical dispersants using experimental 500 l mesocosm tanks that mimic natural ecosystems. The tanks were filled with seawater spiked with the water-soluble fraction of heavy residual oil. Water samples and settling particles in the tanks were collected periodically and 38 PAH compounds were analyzed by gas chromatography-mass spectrometry (GC-MS). Low molecular weight (LMW) PAHs with less than three benzene rings disappeared rapidly, mostly within 2 days. On the other hand, high molecular weight (HMW) PAHs with more than four benzene rings remained in the water column for a longer time, up to 9 days. Also, significant portions (10-94%) of HMW PAHs settled to the bottom and were caught in the sediment trap. The addition of chemical dispersant accelerated dissolution and biodegradation of PAHs, especially HMW PAHs. The dispersant amplified the amounts of PAHs found in the water column. The amplification was the greater for the more hydrophobic PAHs, with an enrichment factor of up to six times. The increased PAHs resulting from dispersant use overwhelmed the normal degradation and, as a result, higher concentrations of PAHs were observed in water column throughout the experimental period. We conclude that the addition of the dispersant could increase the concentration of water column PAHs and thus increase the exposure and potential toxicity for organisms in the natural environment. By making more hydrocarbon material available to the water column, the application of dispersant reduced the settling of PAHs. For the tank with dispersant, only 6% of chrysene initially introduced was detected in the sediment trap whereas 70% was found in the trap in the tank without dispersant. PMID:12787605

  17. Physico-chemical characterization of SOA derived from catechol and guaiacol - a model substance for the aromatic fraction of atmospheric HULIS

    NASA Astrophysics Data System (ADS)

    Ofner, J.; Krüger, H.-U.; Grothe, H.; Schmitt-Kopplin, P.; Whitmore, K.; Zetzsch, C.

    2011-01-01

    Secondary organic aerosol (SOA) was produced from the aromatic precursors catechol and guaiacol by reaction with ozone in the presence and absence of simulated sunlight and humidity and investigated for its properties as a proxy for HUmic-LIke Substances (HULIS). Beside a small particle size, a relatively low molecular weight and typical optical features in the UV/VIS spectral range, HULIS contain a typical aromatic and/or olefinic chemical structure and highly oxidized functional groups within a high chemical diversity. Various methods were used to characterize the secondary organic aerosols obtained: Fourier transform infrared spectroscopy (FTIR) demonstrated the formation of several carbonyl containing functional groups as well as structural and functional differences between aerosols formed at different environmental conditions. UV/VIS spectroscopy of filter samples showed that the particulate matter absorbs far into the visible range up to more than 500 nm. Ultrahigh resolved mass spectroscopy (ICR-FT/MS) determined O/C-ratios between 0.3 and 1 and observed m/z ratios between 200 and 450 to be most abundant. Temperature-programmed-pyrolysis mass spectroscopy (TPP-MS) identified carboxylic acids and lactones/esters as major functional groups. Particle sizing using a condensation-nucleus-counter and differential-mobility-particle-sizer (CNC/DMPS) monitored the formation of small particles during the SOA formation process. Particle imaging, using field-emission-gun scanning electron microscopy (FEG-SEM), showed spherical particles, forming clusters and chains. We conclude that catechol and guaiacol are appropriate precursors for studies of the processing of aromatic SOA with atmospheric HULIS properties on the laboratory scale.

  18. Chemical composition and anti-mosquito potential of rhizome extract and volatile oil derived from Curcuma aromatica against Aedes aegypti (Diptera: Culicidae).

    PubMed

    Choochote, Wej; Chaiyasit, Dana; Kanjanapothi, Duangta; Rattanachanpichai, Eumporn; Jitpakdi, Atchariya; Tuetun, Benjawan; Pitasawat, Benjawan

    2005-12-01

    Crude rhizome extracts and volatile oils of Curcuma aromatica were evaluated for chemical composition and anti-mosquito potential, including larvicidal, adulticidal, and repellent activities against the Aedes aegypti mosquito. Chemical identification achieved by GC/MS analysis revealed that xanthorrhizol, 1H-3a, 7-methanoazulene and curcumene at 35.08 and 13.65%, 21.81 and 30.02%, and 13.75 and 25.71%, were the main constituents in hexane extracts and volatile oils, respectively. Volatile oil of Cu. aromatica possessed a significantly higher larvicidal activity against the 4th instar larvae of Ae. aegypti than that of hexane extracts, with LC50 values of 36.30 and 57.15 ppm, respectively. In testing for adulticidal activity, on the other hand, hexane-extracted Cu. aromatica (LC50: 1.60 microg/mg female) was found to be slightly more effective against female Ae. aegypti than volatile oil (LC50: 2.86 microg/mg female). However, the repellency of these two products against Ae. aegypti adult females differed significantly. The hexane-extracted Cu. aromatica, with a median complete protection time of 1 h (range = 1-1.5 h) when applied at a concentration of 25%, appeared to have significantly higher repellency than that of distillate oil (0.5 h, range = 0-0.5 h). The different results obtained from both products of Cu. aromatica were probably due to variety in quantity and type of active ingredients as well as the biological and physiological characteristics that differed between both developmental stages of mosquitoes, larvae, and adults. PMID:16599168

  19. Hydroxamic acids derived from 2-hydroxy-2H-1,4-benzoxazin-3(4H)-one: key defense chemicals of cereals.

    PubMed

    Niemeyer, Hermann M

    2009-03-11

    Many cereals accumulate hydroxamic acids derived from 2-hydroxy-2H-1,4-benzoxazin-3(4H)-one. These benzoxazinoid hydroxamic acids are involved in defense of maize against various lepidopteran pests, most notably the European corn borer, in defense of cereals against various aphid species, and in allelopathy affecting the growth of weeds associated with rye and wheat crops. The role of benzoxazinoid hydroxamic acids in defense against fungal infection is less clear and seems to depend on the nature of the interactions at the plant-fungus interface. Efficient use of benzoxazinoid hydroxamic acids as resistance factors has been limited by the inability to selectively increase their levels at the plant growth stage and the plant tissues where they are mostly needed for a given pest. Although the biosynthesis of benzoxazinoid hydroxamic acids has been elucidated, the genes and mechanisms controlling their differential expression in different plant tissues and along plant ontogeny remain to be unraveled. PMID:19199602

  20. Saturated amine oxides: Part 8. Hydroacridines: Part 27. Effects of N-oxidation and of N-quaternization on the 15N NMR chemical shifts of N-methylpiperidine-derived mono-, bi-, and tricycloaliphatic tertiary amines.

    PubMed

    Potmischil, Francisc; Duddeck, Helmut; Nicolescu, Alina; Deleanu, Calin

    2007-03-01

    The (15)N chemical shifts of 13 N-methylpiperidine-derived mono-, bi- and tricycloaliphatic tertiary amines, their methiodides and their N-epimeric pairs of N-oxides were measured, and the contributions of specific structural parameters to the chemical shifts were determined by multilinear regression analysis. Within the examined compounds, the effects of N-oxidation upon the (15)N chemical shifts of the amines vary from +56 ppm to +90 ppm (deshielding), of which approx. +67.7 ppm is due to the inductive effect of the incoming N(+)--O(-) oxygen atom, whereas the rest is due to the additive shift effects of the various C-alkyl substituents of the piperidine ring. The effects of quaternization vary from -3.1 ppm to +29.3 ppm, of which approx. +8.9 ppm is due to the inductive effect of the incoming N(+)--CH(3) methyl group, and the rest is due to the additive shift effects of the various C-alkyl substituents of the piperidine ring. The shift effects of the C-alkyl substituents in the amines, the N-oxides and the methiodides are discussed. PMID:17221923

  1. Sounding of the Atmosphere using Broadband Emission Radiometry observations of daytime mesospheric O2(1?) 1.27 ?m emission and derivation of ozone, atomic oxygen, and solar and chemical energy deposition rates

    NASA Astrophysics Data System (ADS)

    Mlynczak, Martin G.; Marshall, B. Thomas; Martin-Torres, F. Javier; Russell, James M.; Thompson, R. Earl; Remsberg, Ellis E.; Gordley, Larry L.

    2007-08-01

    We report observations of the daytime O2(1?) airglow emission at 1.27 ?m recorded by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite. The measured limb radiances are inverted to yield vertical profiles of the volume emission rate of energy from the O2 molecule. From these emission rates we subsequently derive the mesospheric ozone concentrations using a nonlocal thermodynamic equilibrium (non-LTE) radiative and kinetic model. Rates of energy deposition due to absorption of ultraviolet radiation in the Hartley band of ozone are also derived, independent of knowledge of the ozone abundance and solar irradiances. Atomic oxygen concentrations are obtained from the ozone abundance using photochemical steady state assumptions. Rates of energy deposition due to exothermic chemical reactions are also derived. The data products illustrated here are from a test day (4 July 2002) of SABER Version 1.07 data which are now becoming publicly available. This test day illustrates the high quality of the SABER O2(1?) airglow and ozone data and the variety of fundamental science questions to which they can be applied.

  2. Can Small Chemical Modifications of Natural Pan-inhibitors Modulate the Biological Selectivity? The Case of Curcumin Prenylated Derivatives Acting as HDAC or mPGES-1 Inhibitors.

    PubMed

    Iranshahi, Mehrdad; Chini, Maria Giovanna; Masullo, Milena; Sahebkar, Amirhossein; Javidnia, Azita; Chitsazian Yazdi, Mahsa; Pergola, Carlo; Koeberle, Andreas; Werz, Oliver; Pizza, Cosimo; Terracciano, Stefania; Piacente, Sonia; Bifulco, Giuseppe

    2015-12-24

    Curcumin, or diferuloylmethane, a polyphenolic molecule isolated from the rhizome of Curcuma longa, is reported to modulate multiple molecular targets involved in cancer and inflammatory processes. On the basis of its pan-inhibitory characteristics, here we show that simple chemical modifications of the curcumin scaffold can regulate its biological selectivity. In particular, the curcumin scaffold was modified with three types of substituents at positions C-1, C-8, and/or C-8' [C5 (isopentenyl, 5-8), C10 (geranyl, 9-12), and C15 (farnesyl, 13, 14)] in order to make these molecules more selective than the parent compound toward two specific targets: histone deacetylase (HDAC) and microsomal prostaglandin E2 synthase-1 (mPGES-1). From combined in silico and in vitro analyses, three selective inhibitors by proper substitution at position 8 were revealed. Compound 13 has improved HDAC inhibitory activity and selectivity with respect to the parent compound, while 5 and 9 block the mPGES-1 enzyme. We hypothesize about the covalent interaction of curcumin, 5, and 9 with the mPGES-1 binding site. PMID:26588603

  3. Fabrication and energy-storage performance of (Pb,La)(Zr,Ti)O3 antiferroelectric thick films derived from polyvinylpyrrolidone-modified chemical solution

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Hao, Xihong; Yang, Jichun; Xu, Jinbao; Zhao, Diyi

    2012-08-01

    In this work, Pb0.97La0.02(Zr0.98Ti0.02)O3 (PLZT 2/98/2) antiferroelectric (AFE) thick films were successfully deposited on LaNiO3/Si(100) substrates by polyvinylpyrrolidone (PVP)-modified chemical solution. Each wet layer was first dried at 300 C and then pyrolyzed at higher temperature B of 600, 650, or 700 C, respectively. The effects of the pyrolyzed temperature B on the microstructure and the energy-storage performance of the AFE films were investigated in detail. As the increasing of the pyrolyzed temperature, the crystallized PLZT 2/98/2 films displayed a more uniform and dense surface microstructure. As a result, the dielectric properties, AFE characterization, and energy-storage performance were remarkably improved for the AFE thick films pyrolyzed at higher temperature. The maximum energy-storage density of 58.1 J/cm3 and the corresponding energy-storage efficiency of 37.3% were obtained in the PLZT 2/98/2 films pyrolyzed at 700 C for every layer.

  4. Assessment and Applications of NASA Ozone Data Products Derived from Aura OMI-MLS Satellite Measurements in Context of the GMI Chemical Transport Model

    NASA Technical Reports Server (NTRS)

    Ziemke, J. R.; Olsen, M. A.; Witte, J. C.; Douglass, A. R.; Strahan, S. E.; Wargan, K.; Liu, X.; Schoeberl, M. R.; Yang, K.; Kaplan, T. B.; Pawson, S.; Duncan, B. N.; Newman, P. A.; Bhartia, K.; Heney, M. K.

    2013-01-01

    Measurements from the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS), both onboard the Aura spacecraft, have been used to produce daily global maps of column and profile ozone since August 2004. Here we compare and evaluate three strategies to obtain daily maps of tropospheric and stratospheric ozone from OMI and MLS measurements: trajectory mapping, direct profile retrieval, and data assimilation. Evaluation is based upon an assessment that includes validation using ozonesondes and comparisons with the Global Modeling Initiative (GMI) chemical transport model (CTM). We investigate applications of the three ozone data products from near-decadal and inter-annual timescales to day-to-day case studies. Zonally averaged inter-annual changes in tropospheric ozone from all of the products in any latitude range are of the order 1-2 Dobson Units while changes (increases) over the 8-year Aura record investigated http://eospso.gsfc.nasa.gov/atbd-category/49 vary approximately 2-4 Dobson Units. It is demonstrated that all of the ozone products can measure and monitor exceptional tropospheric ozone events including major forest fire and pollution transport events. Stratospheric ozone during the Aura record has several anomalous inter-annual events including stratospheric warming split events in the Northern Hemisphere extra-tropics that are well captured using the data assimilation ozone profile product. Data assimilation with continuous daily global coverage and vertical ozone profile information is the best of the three strategies at generating a global tropospheric and stratospheric ozone product for science applications.

  5. Chemical Composition and Biological Activity of Extracts Obtained by Supercritical Extraction and Ethanolic Extraction of Brown, Green and Red Propolis Derived from Different Geographic Regions in Brazil

    PubMed Central

    Machado, Bruna Aparecida Souza; Silva, Rejane Pina Dantas; Barreto, Gabriele de Abreu; Costa, Samantha Serra; da Silva, Danielle Figuerêdo; Brandão, Hugo Neves; da Rocha, José Luiz Carneiro; Dellagostin, Odir Antônio; Henriques, João Antônio Pegas; Umsza-Guez, Marcelo Andres; Padilha, Francine Ferreira

    2016-01-01

    The variations in the chemical composition, and consequently, on the biological activity of the propolis, are associated with its type and geographic origin. Considering this fact, this study evaluated propolis extracts obtained by supercritical extraction (SCO2) and ethanolic extraction (EtOH), in eight samples of different types of propolis (red, green and brown), collected from different regions in Brazil. The content of phenolic compounds, flavonoids, in vitro antioxidant activity (DPPH and ABTS), Artepillin C, p-coumaric acid and antimicrobial activity against two bacteria were determined for all extracts. For the EtOH extracts, the anti-proliferative activity regarding the cell lines of B16F10, were also evaluated. Amongst the samples evaluated, the red propolis from the Brazilian Northeast (states of Sergipe and Alagoas) showed the higher biological potential, as well as the larger content of antioxidant compounds. The best results were shown for the extracts obtained through the conventional extraction method (EtOH). However, the highest concentrations of Artepillin C and p-coumaric acid were identified in the extracts from SCO2, indicating a higher selectivity for the extraction of these compounds. It was verified that the composition and biological activity of the Brazilian propolis vary significantly, depending on the type of sample and geographical area of collection. PMID:26745799

  6. Chemical composition and larvicidal activity of edible plant-derived essential oils against the pyrethroid-susceptible and -resistant strains of Aedes aegypti (Diptera: Culicidae).

    PubMed

    Sutthanont, Nataya; Choochote, Wej; Tuetun, Benjawan; Junkum, Anuluck; Jitpakdi, Atchariya; Chaithong, Udom; Riyong, Doungrat; Pitasawat, Benjawan

    2010-06-01

    The chemical compositions and larvicidal potential against mosquito vectors of selected essential oils obtained from five edible plants were investigated in this study. Using a GC/MS, 24, 17, 20, 21, and 12 compounds were determined from essential oils of Citrus hystrix, Citrus reticulata, Zingiber zerumbet, Kaempferia galanga, and Syzygium aromaticum, respectively. The principal constituents found in peel oil of C. hystrix were beta-pinene (22.54%) and d-limonene (22.03%), followed by terpinene-4-ol (17.37%). Compounds in C. reticulata peel oil consisted mostly of d-limonene (62.39%) and gamma-terpinene (14.06%). The oils obtained from Z. zerumbet rhizome had alpha-humulene (31.93%) and zerumbone (31.67%) as major components. The most abundant compounds in K. galanga rhizome oil were 2-propeonic acid (35.54%), pentadecane (26.08%), and ethyl-p-methoxycinnamate (25.96%). The main component of S. aromaticum bud oil was eugenol (77.37%), with minor amounts of trans-caryophyllene (13.66%). Assessment of larvicidal efficacy demonstrated that all essential oils were toxic against both pyrethroid-susceptible and resistant Ae. aegypti laboratory strains at LC50, LC95, and LC99 levels. In conclusion, we have documented the promising larvicidal potential of essential oils from edible herbs, which could be considered as a potentially alternative source for developing novel larvicides to be used in controlling vectors of mosquito-borne disease. PMID:20618656

  7. An Intercomparison and Evaluation of Aircraft-Derived and Simulated CO from Seven Chemical Transport Models During the TRACE-P Experiment

    NASA Technical Reports Server (NTRS)

    Kiley, C. M.; Fuelberg, Henry E.; Palmer, P. I.; Allen, D. J.; Carmichael, G. R.; Jacob, D. J.; Mari, C.; Pierce, R. B.; Pickering, K. E.; Tang, Y.

    2002-01-01

    Four global scale and three regional scale chemical transport models are intercompared and evaluated during NASA's TRACE-P experiment. Model simulated and measured CO are statistically analyzed along aircraft flight tracks. Results for the combination of eleven flights show an overall negative bias in simulated CO. Biases are most pronounced during large CO events. Statistical agreements vary greatly among the individual flights. Those flights with the greatest range of CO values tend to be the worst simulated. However, for each given flight, the models generally provide similar relative results. The models exhibit difficulties simulating intense CO plumes. CO error is found to be greatest in the lower troposphere. Convective mass flux is shown to be very important, particularly near emissions source regions. Occasionally meteorological lift associated with excessive model-calculated mass fluxes leads to an overestimation of mid- and upper- tropospheric mixing ratios. Planetary Boundary Layer (PBL) depth is found to play an important role in simulating intense CO plumes. PBL depth is shown to cap plumes, confining heavy pollution to the very lowest levels.

  8. Chemical Composition and Biological Activity of Extracts Obtained by Supercritical Extraction and Ethanolic Extraction of Brown, Green and Red Propolis Derived from Different Geographic Regions in Brazil.

    PubMed

    Machado, Bruna Aparecida Souza; Silva, Rejane Pina Dantas; Barreto, Gabriele de Abreu; Costa, Samantha Serra; Silva, Danielle Figuerdo da; Brando, Hugo Neves; Rocha, Jos Luiz Carneiro da; Dellagostin, Odir Antnio; Henriques, Joo Antnio Pegas; Umsza-Guez, Marcelo Andres; Padilha, Francine Ferreira

    2016-01-01

    The variations in the chemical composition, and consequently, on the biological activity of the propolis, are associated with its type and geographic origin. Considering this fact, this study evaluated propolis extracts obtained by supercritical extraction (SCO2) and ethanolic extraction (EtOH), in eight samples of different types of propolis (red, green and brown), collected from different regions in Brazil. The content of phenolic compounds, flavonoids, in vitro antioxidant activity (DPPH and ABTS), Artepillin C, p-coumaric acid and antimicrobial activity against two bacteria were determined for all extracts. For the EtOH extracts, the anti-proliferative activity regarding the cell lines of B16F10, were also evaluated. Amongst the samples evaluated, the red propolis from the Brazilian Northeast (states of Sergipe and Alagoas) showed the higher biological potential, as well as the larger content of antioxidant compounds. The best results were shown for the extracts obtained through the conventional extraction method (EtOH). However, the highest concentrations of Artepillin C and p-coumaric acid were identified in the extracts from SCO2, indicating a higher selectivity for the extraction of these compounds. It was verified that the composition and biological activity of the Brazilian propolis vary significantly, depending on the type of sample and geographical area of collection. PMID:26745799

  9. Assessment and Applications of NASA Ozone Data Products Derived from Aura OMI/MLS Satellite Measurements in Context of the GMI Chemical Transport Model

    NASA Astrophysics Data System (ADS)

    Ziemke, J. R.; Olsen, M. A.; Witte, J. C.; Douglass, A. R.

    2014-12-01

    Measurements from the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS), both onboard the Aura spacecraft, have been used to produce daily global maps of column and profile ozone since August 2004. Here we compare and evaluate three strategies to obtain daily maps of tropospheric and stratospheric ozone from OMI and MLS measurements: trajectory mapping, direct profile retrieval, and data assimilation. Evaluation is based on an assessment that includes validation using ozonesondes and comparisons with the Global Modeling Initiative (GMI) chemical transport model (CTM). We investigate applications of the three ozone data products from near-decadal and inter-annual timescales to day-to-day case studies. Inter-annual changes in zonal mean tropospheric ozone from all of the products in any latitude range are of the order 1-2 Dobson Units while changes (increases) over the 8-year Aura record investigated vary by 2-4 Dobson Units. It is demonstrated that all of the ozone products can measure and monitor exceptional tropospheric ozone events including major forest fire and pollution transport events. Stratospheric ozone during the Aura record has several anomalous inter-annual events including split stratospheric warmings in the Northern Hemisphere extra-tropics that are well captured using the data assimilation ozone profile product. Data assimilation with continuous daily global coverage and vertical ozone profile information is the best of the three strategies at generating a global tropospheric and stratospheric ozone product for science applications.

  10. Growth of ferroelectric Ba0.8Sr0.2TiO3 epitaxial films by ultraviolet pulsed laser irradiation of chemical solution derived precursor layers

    NASA Astrophysics Data System (ADS)

    Queralt, A.; Prez del Pino, A.; de la Mata, M.; Arbiol, J.; Tristany, M.; Gmez, A.; Obradors, X.; Puig, T.

    2015-06-01

    Highly crystalline epitaxial Ba0.8Sr0.2TiO3 (BST) thin-films are grown on (001)-oriented LaNiO3-buffered LaAlO3 substrates by pulsed laser irradiation of solution derived barium-zirconium-titanium precursor layers using a UV Nd:YAG laser source at atmospheric conditions. The structural analyses of the obtained films, studied by X-ray diffractometry and transmission electron microscopy, demonstrate that laser processing allows the growth of tens of nm-thick BST epitaxial films with crystalline structure similar to that of films obtained through conventional thermal annealing methods. However, the fast pulsed nature of the laser employed leads to crystallization kinetic evolution orders of magnitude faster than in thermal treatments. The combination of specific photothermal and photochemical mechanisms is the main responsible for the ultrafast epitaxial laser-induced crystallization. Piezoresponse microscopy measurements demonstrate equivalent ferroelectric behavior in laser and thermally annealed films, being the piezoelectric constant 25 pm V-1.

  11. Part I. Naltrexone-derived conjugate addition ligands for opioid receptors. Part II. Chemical and enantioselective aspects of the metabolism of verapamil

    SciTech Connect

    Olsen, L.D.

    1987-01-01

    Selective chemoaffinity ligands to aid in identification and purification of opioid receptor subtypes were prepared from 6..cap alpha..- and 6..beta..-naltrexol, obtained stereoselectively from the ..mu..-receptor antagonist naltrexone. The targets were the 6..cap alpha..- and 6..beta..-methacrylate ethers and 6..cap alpha..- and 6..beta..-methacrylate esters prepared from reaction of 6..cap alpha..- and 6..beta..-naltrexol with methyl ..cap alpha..-(bromomethyl)acrylate or methacryloyl chloride. Of three methacrylate derivatives, the 6..cap alpha..-ether was the most potent in an opioid receptor binding assay with (/sup 3/H)-naltrexone. In the presence of sodium ion, preincubation of the 6..cap alpha..-ether resulted in recovery of about 60% of original (/sup 3/H)-naltrexone binding suggesting some irreversible effects. The methacrylate esters precipitated withdrawal in morphine dependent monkeys. The enantiomers of verapamil, a calcium channel antagonist, have different pharmacological and pharmacokinetic properties. The oxidative metabolism of verapamil was studied in rat and human liver microsomes and in man after a single oral dose.

  12. Synthesis, antimicrobial evaluation and theoretical prediction of NMR chemical shifts of thiazole and selenazole derivatives with high antifungal activity against Candida spp.

    NASA Astrophysics Data System (ADS)

    Łączkowski, Krzysztof Z.; Motylewska, Katarzyna; Baranowska-Łączkowska, Angelika; Biernasiuk, Anna; Misiura, Konrad; Malm, Anna; Fernández, Berta

    2016-03-01

    Synthesis and investigation of antimicrobial activities of novel thiazoles and selenazoles is presented. Their structures were determined using NMR, FAB(+)-MS, HRMS and elemental analyses. To support the experiment, theoretical calculations of the 1H NMR shifts were carried out for representative systems within the DFT B3LYP/6-311++G** approximation which additionally confirmed the structure of investigated compounds. Among the derivatives, compounds 4b, 4h, 4j and 4l had very strong activity against reference strains of Candida albicans ATCC and Candida parapsilosis ATCC 22019 with MIC = 0.49-7.81 μg/ml. In the case of compounds 4b, 4c, 4h - 4j and 4l, the activity was very strong against of Candida spp. isolated from clinical materials, i.e. C. albicans, Candida krusei, Candida inconspicua, Candida famata, Candida lusitaniae, Candida sake, C. parapsilosis and Candida dubliniensis with MIC = 0.24-15.62 μg/ml. The activity of several of these was similar to the activity of commonly used antifungal agent fluconazole. Additionally, compounds 4m - 4s were found to be active against Gram-positive bacteria, both pathogenic staphylococci Staphylococcus aureus ATCC with MIC = 31.25-125 μg/ml and opportunistic bacteria, such as Staphylococcus epidermidis ATCC 12228 and Micrococcus luteus ATCC 10240 with MIC = 7.81-31.25 μg/ml.

  13. The integration of data on physico-chemical properties, in vitro-derived toxicity data and physiologically based kinetic and dynamic as modelling a tool in hazard and risk assessment. A commentary.

    PubMed

    Blaauboer, B J

    2003-02-18

    Toxicity of a compound for an organism is dependent on the route of exposure, the amount (or concentration), the way in which the compound is taken up, distributes and is eliminated from the organism (ADME, kinetics) and the intrinsic properties (reactivity; mode of action, dynamics) of the compound towards the organism. These three elements: exposure, kinetics and dynamics form the basis of hazard and risk evaluations. Developments in our knowledge of the way in which physico-chemical properties of chemicals (on the one side) and physiological processes in the organism (on the other side) determine a compound's toxicity have greatly increased our understanding of toxicological processes and our ability to interpret experimental results. This has now resulted in the development of model systems in which the above-mentioned processes can be described mathematically. Biokinetic modelling is currently of great interest, but the further development of toxicodynamic modelling is equally important. The combination of both allows the estimation of a compound's critical amount/concentration on the critical site of action, which ideally would be the basis for hazard and risk assessments. In vitro systems have been extremely useful in studying the molecular basis of a chemical's biological activity, including its mechanism(s) of toxic action. Other achievements include the prediction of biological reactivity on the basis of a compound's physico-chemical properties and the construction of quantitative structure-activity relationships (QSARs). However, for the incorporation of in vitro-derived data as well as the results of QSARs, kinetic modelling is indispensable. Thus, biokinetic and toxicodynamic modelling are important (if not crucial) tools in toxicological research and there are increasing opportunities to incorporate the results of this work in hazard and risk assessments. Their implementation will allow a much more scientifically-based and a better structured risk assessment, which will be to a much lesser extent relying on animal experimentation. PMID:12559700

  14. Electrochemical and chemical oxidation of [Pt2(mu-pyrophosphite)4]4- revisited: characterization of a nitrosyl derivative, [Pt2(mu-pyrophosphite)4(NO)]3-.

    PubMed

    Bennett, Martin A; Bhargava, Suresh K; Bond, Alan M; Bansal, Vipul; Forsyth, Craig M; Guo, Si-Xuan; Privér, Steven H

    2009-03-16

    Electrochemical studies of the salts [cat](4)[Pt(2)(mu-pop)(4)] (cat(+) = Bu(4)N(+) or PPN(+) [Ph(3)P=N=PPh(3)](+); pop = pyrophosphite, [P(2)O(5)H(2)](2-)) have been carried out in dichloromethane. In agreement with published studies of K(4)[Pt(2)(mu-pop)(4)] in water and [Ph(4)As](4)[Pt(2)(mu-pop)(4)] in acetonitrile, the [Pt(2)(mu-pop)(4)](4-) anion is found to undergo an initial one-electron oxidation under conditions of cyclic voltammetry to a short-lived trianion, [Pt(2)(mu-pop)(4)](3-). However, in the more weakly coordinating solvent dichloromethane, [Pt(2)(mu-pop)(4)](3-) appears to undergo oligomerization instead of solvent-induced disproportionation; thus the overall process remains a one-electron reaction rather than an overall two-electron oxidative addition process, even under long time-scale, bulk electrolysis conditions. Chemical oxidation of [cat](4)[Pt(2)(mu-pop)(4)] with [NO][BF(4)] or AgBF(4) gives mainly a dark, insoluble, ill-defined solid that appears to contain Pt(III) according to X-ray photoelectron spectroscopy (XPS). In the case of [NO][BF(4)], a second reaction product, an orange solid, has been identified as a nitrosyl complex, [cat](3)[Pt(2)(mu-pop)(4)(NO)]. The X-ray structure of the PPN(+) salt shows the anion to consist of the usual lantern-shaped Pt(2)(mu-pop)(4) framework with an unusually large Pt-Pt separation [2.8375(6) A]; one of the platinum atoms carries a bent nitrosyl group [r(N-O) = 1.111(15) A; angle(Pt-N-O) = 118.1(12) degrees] occupying an axial position. The nitrosyl group migrates rapidly on the (31)P NMR time-scale between the metal atoms at room temperature but the motion is slow enough at 183 K that the expected two pairs of inequivalent phosphorus nuclei can be observed. The X-ray photoelectron (XP) spectrum of the nitrosyl-containing anion confirms the presence of two inequivalent platinum atoms whose 4f(7/2) binding energies are in the ranges expected for Pt(II) and Pt(III); an alternative interpretation is that the second platinum atom has a formal oxidation number of +4 and that its binding energy is modified by the strongly sigma-donating NO(-) ligand. Reduction of [Pt(2)(mu-pop)(4)X(2)](4-) (X = Cl, Br, I) in dichloromethane corresponds to a chemically reversible, electrochemically irreversible two-electron process involving loss of halide and formation of [Pt(2)(mu-pop)(4)](4-), as is the case in more strongly coordinating solvents. PMID:19226168

  15. History of the paired lunar meteorites MAC88104 and MAC88105 derived from noble gas isotopes, radionuclides, and some chemical abundances

    SciTech Connect

    Eugster, O.; Burger, M.; Kraehenbuehl, U.; Michel, T. ); Beer, J. ); Finkel, R.C. ); Hofmann, H.J.; Synal, H.A.; Woelfli, W. )

    1991-11-01

    Noble gas isotopes, radionuclides, and chemical abundances were studied in the lunar meteorites MAC88104 and MAC88105 collected in the MacAlpine Hills area of Antarctica. The concentrations of the noble gas isotopes and the radionuclide activities in the two meteorites are essentially identical, proving that the two meteorites are paired. From {sup 40}K-{sup 40}Ar dating the authors obtain a gas retention age of 3,550 {plus minus} 400 Ma, typical for lunar surface material. Probably before breccia compaction the MAC88104/5 material resided for 630 {plus minus} 200 Ma at an average shielding depth of 85 g/cm{sup 2}, that is, about 50 cm below the lunar surface in the lunar regolith, as judged from the concentration of cosmic-ray produced Kr and Xe isotopes. Although this duration of lunar regolith residence is relatively long, MAC88104/5 represent immature regolith material: the concentration of solar wind implanted noble gases are two orders of magnitude lower than those in mature lunar soil. The {sup 40}Ar/{sup 36}Ar ratio of the trapped component is 5.7 {plus minus} 1.0, indicating an intermediate antiquity of the material; the authors estimate that the solar wind and lunar atmospheric particles were implanted about 2,000 Ma ago. The radionuclide activities allow a determination of the exposure history of the MAC88104/5 material. The duration of the Moon-Earth transfer was {much lt} 0.24 Ma. The exposure histories of the lunar meteorites discussed in this work indicate that at least two impact events are required for their ejection from the Moon. The authors first noble gas results for lunar meteorite Yamato-793274 show that it represents mature lunar regolith material with relatively high concentrations of solar wind implanted noble gas and a duration of several hundred million years of exposure to cosmic rays.

  16. Spatiotemporal gradients in aerosol radiative forcing and heating rate over Bay of Bengal and Arabian Sea derived on the basis of optical, physical, and chemical properties

    NASA Astrophysics Data System (ADS)

    Kedia, Sumita; Ramachandran, S.; Kumar, Ashwini; Sarin, M. M.

    2010-04-01

    Spatiotemporal heterogeneity in aerosol radiative forcing and heating rate have been studied over Bay of Bengal and Arabian Sea during premonsoon (March-May 2006) using aerosol optical depth (AOD), total mass, aerosol chemical composition, and radiative transfer model. Mean 0.5 ?m AOD over Bay of Bengal and Arabian Sea is 0.36 and 0.25, respectively. Water-soluble aerosols, sea salt, and mineral dust constitute 98% of total aerosol mass while black carbon aerosols contribute ?2% over the two oceanic regions. Sensitivity tests reveal that (1) curvature effect in AOD spectra has insignificant impact in modifying the aerosol radiative forcing and heating rate and (2) the net Earth-atmosphere energy content shows minor differences when aerosol vertical profiles are used. Over Bay of Bengal the average aerosol forcing is estimated to be -12.0, -22.4, and 10.4 W m-2 at the top of the atmosphere (TOA), at the surface (SFC), and in atmosphere (ATM), respectively. The average aerosol radiative forcing is less negative over Arabian Sea and is -10.5, -15.8, and 5.3 W m-2 at TOA, SFC, and ATM, respectively. Aerosol radiative forcing decreases in magnitude from north to south over Bay of Bengal whereas an opposite trend is noteworthy over Arabian Sea. The average atmospheric heating rate over Bay of Bengal is 0.3 K/d, a factor of 2 higher than that over Arabian Sea. Furthermore, ATM warming and associated heating rate are the lowest compared to earlier results as scattering aerosols are dominant during premonsoon (March-May). These results have implications to the assessment of regional and seasonal climate impacts.

  17. Chemical characterization of ASTA Z 7557 (INN mafosfamide, CIS-4-sulfoethylthio-cyclophosphamide), a stable derivative of 4-hydroxy-cyclophosphamide.

    PubMed

    Niemeyer, U; Engel, J; Scheffler, G; Molge, K; Sauerbier, D; Weigert, W

    1984-01-01

    The primary metabolite of cyclophosphamide (CP, 1), i.e. 4-hydroxy-CP 2, has high pharmacological activity, but it is a very unstable compound. Chemical approaches to the stabilization involved in the substitution of the hydroxy group at the C 4-position, especially by a sulfoalkylthio-moiety. Within this new class of compounds ASTA Z 7557 (2-(bis-(2-chloroethyl]-amino-cis-4-[2-sulfoethyl)-thio)-tetrah ydr o-2H-1,3, 2-oxaza-phosphorine-r-2-oxide cyclohexylamine salt, i.e. cis-4-sulfoethylthio-CP, cis-13) was chosen for further evaluation. Cis-13 was synthesized by condensation of compound 2 and 2-mercapto-ethanesulfonic acid cyclohexylamine salt 14 in aqueous acetone yielding the cis-isomer with high stereoselectivity. It is a white crystalline powder, m.p. 126-134 degrees C, stable at room temperature, with a solubility of 16% in water. The stereochemistry was confirmed by NMR-data and X-ray diffraction. In 0.07 M phosphate buffer at pH 7 and 37 degrees C cis-13 isomerizes to the epimer trans-13, equilibrating at a cis-trans-ratio of 59 to 41 within less than 5 minutes. Simultaneously a rapid initial hydrolysis occurs to 2 and 14 followed by a time period with lower degradation due to the decomposition of 2. The rate of release of 2 increases with decreasing concentration and especially by addition of an oxidant. It could be retarded by addition of the corresponding thiol mesna, sodium 2-mercapto-ethanesulfonate 15, or of another thiol.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6469506

  18. Systemic approaches identify a garlic-derived chemical, Z-ajoene, as a glioblastoma multiforme cancer stem cell-specific targeting agent.

    PubMed

    Jung, Yuchae; Park, Heejoo; Zhao, Hui-Yuan; Jeon, Raok; Ryu, Jae-Ha; Kim, Woo-Young

    2014-07-01

    Glioblastoma multiforme (GBM) is one of the most common brain malignancies and has a very poor prognosis. Recent evidence suggests that the presence of cancer stem cells (CSC) in GBM and the rare CSC subpopulation that is resistant to chemotherapy may be responsible for the treatment failure and unfavorable prognosis of GBM. A garlic-derived compound, Z-ajoene, has shown a range of biological activities, including anti-proliferative effects on several cancers. Here, we demonstrated for the first time that Z-ajoene specifically inhibits the growth of the GBM CSC population. CSC sphere-forming inhibition was achieved at a concentration that did not exhibit a cytotoxic effect in regular cell culture conditions. The specificity of this inhibitory effect on the CSC population was confirmed by detecting CSC cell surface marker CD133 expression and biochemical marker ALDH activity. In addition, stem cell-related mRNA profiling and real-time PCR revealed the differential expression of CSC-specific genes, including Notch, Wnt, and Hedgehog, upon treatment with Z-ajoene. A proteomic approach, i.e., reverse-phase protein array (RPPA) and Western blot analysis, showed decreased SMAD4, p-AKT, 14.3.3 and FOXO3A expression. The protein interaction map (http://string-db.org/) of the identified molecules suggested that the AKT, ERK/p38 and TGF? signaling pathways are key mediators of Z-ajoene's action, which affects the transcriptional network that includes FOXO3A. These biological and bioinformatic analyses collectively demonstrate that Z-ajoene is a potential candidate for the treatment of GBM by specifically targeting GBM CSCs. We also show how this systemic approach strengthens the identification of new therapeutic agents that target CSCs. PMID:25078449

  19. Evaluating Whole Chemical Mixtures and Sufficient Similarity

    EPA Science Inventory

    This powerpoint presentation supports apresentation describing dose-response assessment for complex chemical mixtures including deriving reference doses for mixtures evaluating sufficient similarity among chemical mixtures.

  20. Quantitative NMR-derived interproton distances combined with quantum mechanical calculations of 13C chemical shifts in the stereochemical determination of conicasterol F, a nuclear receptor ligand from Theonella swinhoei.

    PubMed

    Chini, Maria Giovanna; Jones, Catharine R; Zampella, Angela; D'Auria, Maria Valeria; Renga, Barbara; Fiorucci, Stefano; Butts, Craig P; Bifulco, Giuseppe

    2012-02-01

    Here we report the first application of combined accurate ROE-distance analysis with DFT calculations of NMR chemical shifts to achieve the relative configuration assignment of a marine natural product, conicasterol F, a new polyhydroxylated steroid isolated from the marine sponge Theonella swinhoei. We demonstrate the substantial advantages of this combined approach as a tool for structural studies of natural products, providing a powerful alternative to, or information to underpin, total synthesis when more classical NMR data analysis fails to provide unequivocal results. In this paper, we also describe the isolation and structure elucidation of conicasterol F and its 24-ethyl derivative, theonellasterol I, and their pharmacological evaluation as human nuclear receptor modulators. PMID:22201476

  1. Optimization of water treatment methods for the purification of peat extraction derived runoff: Evaluation of chemical treatment response to variations in incoming water quality using a 2k factorial test design

    NASA Astrophysics Data System (ADS)

    Heiderscheidt, Elisangela; Ronkanen, Anna-Kaisa; Klöve, Björn

    2013-04-01

    The sustainable use of peatland areas requires measures to minimize and when possible eradicate the identified environmental impacts. The drainage of peatlands and other peat extraction, agriculture and forestry activities are known to increase the leaching of pollutant substances resulting in the eutrophication and siltation of receiving water bodies, causing water quality deterioration. Due to the geochemistry characteristics of peat soils the quality of peatland derived runoff water is known to oscillate with location and also with variations in runoff and peak discharge occurrences. Affordable, simple and reliable purification methods that can purify waters rich in particulates, nutrients and dissolved organic carbon while capable of coping with incoming water quality variations are therefore required. Chemical treatment is considered one of the best available technologies for the purification of peat extraction runoff water in Finland; however, until recently little research had been applied on the development of this treatment method for the purification of non-point source pollution. Chemical purification, using metal salts as coagulant agents, is currently applied in several treatment facilities in Finnish peat extraction sites. Nevertheless, variations in runoff water quality and the lack of development of field process parameters has led to the application of high chemical dosages, significant and undesirable fluctuations in purification efficiency and high metal concentration in the discharging waters. This work aims to develop and optimize the chemical purification method by using high level scientific methods to evaluate the response of the purification process to variations in water quality which are typical of peatland derived runoff. The evaluation of how the purification process responds to these variations is a critical step which will enable the development of preventive measures and optimization of relevant process parameters and thus reduce the environmental impacts related to this treatment method. The influence of variations in water quality parameters was accessed using a 2k factorial test design and a well-known chemical purification pilot test procedure (jar test). The k factors or parameters evaluated were: organic matter as chemical oxygen demand (COD 20mg/l and 80mg/l), suspended solids (SS 10mg/l and 60 mg/l), applied coagulant dosage (ferric sulphate 35mg/l and 100mg/l) as well as pH (4.5 and 7.0). Water samples were collected from different peat extraction sites and suitable samples were manipulated using techniques such as centrifugation, dilution and acid or base addition to produce samples with the combinations of high and low concentrations presented. The complete statistical analysis of obtained results will include evaluation of variability using the univariate repeated measures ANOVA as well as the multivariate repeated measures ANOVA methods. Preliminary results of the univariate analyses shows that the interaction between the concentration of a particular substance (COD, SS and pH) and the dosage applied impose significant higher influence on the overall purification efficiency than the substance concentration and applied dosage as individual factors.

  2. Seven New and Two Known Lipopeptides as well as Five Known Polyketides: The Activated Production of Silent Metabolites in a Marine-Derived Fungus by Chemical Mutagenesis Strategy Using Diethyl Sulphate

    PubMed Central

    Wu, Chang-Jing; Li, Chang-Wei; Cui, Cheng-Bin

    2014-01-01

    AD-2-1 is an antitumor fungal mutant obtained by diethyl sulfate mutagenesis of a marine-derived Penicillium purpurogenum G59. The G59 strain originally did not produce any metabolites with antitumor activities in MTT assays using K562 cells. Tracing newly produced metabolites under guidance of MTT assay and TLC analysis by direct comparison with control G59 extract, seven new (17) and two known (89) lipopeptides were isolated together with five known polyketides 1014 from the extract of mutant AD-2-1. Structures of the seven new compounds including their absolute configurations were determined by spectroscopic and chemical evidences and named as penicimutalides AG (17). Seven known compounds were identified as fellutamide B (8), fellutamide C (9), 1?-O-methylaverantin (10), averantin (11), averufin (12), nidurufin (13), and sterigmatocystin (14). In the MTT assay, 114 inhibited several human cancer cell lines to varying extents. All the bioassays and HPLC-photodiode array detector (PDAD)-UV and HPLC-electron spray ionization (ESI)-MS analyses demonstrated that the production of 114 in the mutant AD-2-1 was caused by the activated production of silent metabolites in the original G59 fungal strain. Present results provided additional examples for effectiveness of the chemical mutagenesis strategy using diethyl sulphate mutagenesis to discover new compounds by activating silent metabolites in fungal isolates. PMID:24686557

  3. Biotechnology and derived products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microorganisms able to infect and kill insect pests, metabolites from plants and microorganisms, and transgenic crops are biotechnologically derived products that are being promoted for use to control insect pests in lieu of chemical insecticides. Products based on these technologies effectively co...

  4. Oxygenated Derivatives of Hydrocarbons

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For the book entitled “Insect Hydrocarbons: Biology, Biochemistry and Chemical Ecology”, this chapter presents a comprehensive review of the occurrence, structure and function of oxygenated derivatives of hydrocarbons. The book chapter focuses on the occurrence, structural identification and functi...

  5. 40 CFR 721.1820 - Bisphenol derivative.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Bisphenol derivative. 721.1820 Section... Substances 721.1820 Bisphenol derivative. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as bisphenol derivative (PMN No. P-92-509)...

  6. 40 CFR 721.1820 - Bisphenol derivative.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Bisphenol derivative. 721.1820 Section... Substances 721.1820 Bisphenol derivative. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as bisphenol derivative (PMN No. P-92-509)...

  7. 40 CFR 721.1820 - Bisphenol derivative.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Bisphenol derivative. 721.1820 Section... Substances 721.1820 Bisphenol derivative. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as bisphenol derivative (PMN No. P-92-509)...

  8. 40 CFR 721.1820 - Bisphenol derivative.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Bisphenol derivative. 721.1820 Section... Substances 721.1820 Bisphenol derivative. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as bisphenol derivative (PMN No. P-92-509)...

  9. Radical-assisted chemical doping for chemically derived graphene

    PubMed Central

    2013-01-01

    Carrier doping of graphene is one of the most challenging issues that needs to be solved to enable its use in various applications. We developed a carrier doping method using radical-assisted conjugated organic molecules in the liquid phase and demonstrated all-wet fabrication process of doped graphene films without any vacuum process. Charge transfer interaction between graphene and dopant molecules was directly investigated by spectroscopic studies. The resistivity of the doped graphene films was drastically decreased by two orders of magnitude. The resistivity was improved by not only carrier doping but the improvement in adhesion of doped graphene flakes. First-principles calculation supported the model of our doping mechanism. PMID:24355062

  10. Inquiry of the electron density transfers in chemical reactions: a complete reaction path for the denitrogenation process of 2,3-diazabicyclo[2.2.1]hept-2-ene derivatives.

    PubMed

    Safont, Vicent S; González-Navarrete, Patricio; Oliva, Mónica; Andrés, Juan

    2015-12-28

    A detailed study on all stages associated with the reaction mechanisms for the denitrogenation of 2,3-diazabicyclo[2.2.1]hept-2-ene derivatives (DBX, with X substituents at the methano-bridge carbon atom, X = H and OH) is presented. In particular, we have characterized the processes leading to cycloalkene derivatives through migration-type mechanisms as well as the processes leading to cyclopentil-1,3-diradical species along concerted or stepwise pathways. The reaction mechanisms have been further analysed within the bonding evolution theory framework at B3LYP and M05-2X/6-311+G(2d,p) levels of theory. Analysis of the results allows us to obtain the intimate electronic mechanism for the studied processes, providing a new topological picture of processes underlying the correlation between the experimental measurements obtained by few-optical-cycle visible pulse radiation and the quantum topological analysis of the electron localization function (ELF) in terms of breaking/forming processes along this chemical rearrangement. The evolution of the population of the disynaptic basin V(N1,N2) can be related to the experimental observation associated with the N=N stretching mode evolution, relative to the N2 release, along the reaction process. This result allows us to determine why the N2 release is easier for the DBH case via a concerted mechanism compared to the stepwise mechanism found in the DBOH system. This holds the key to unprecedented insight into the mapping of the electrons making/breaking the bonds while the bonds change. PMID:26584857

  11. Chemical and biological characterisation of sapinopyridione, a phytotoxic 3,3,6-trisubstituted-2,4-pyridione produced by Sphaeropsis sapinea, a toxigenic pathogen of native and exotic conifers, and its derivatives.

    PubMed

    Evidente, Antonio; Fiore, Michele; Bruno, Giovanni; Sparapano, Lorenzo; Motta, Andrea

    2006-05-01

    A phytotoxic trisubstituted 2,4-pyridione, named sapinopyridione, was isolated from the culture filtrates of Sphaeropsis sapinea, a fungal pathogen of conifers occurring world-wide. Three strains were isolated from two cypress species. Strain D-55 isolated from Cupressus sempervirens resulted high producer of sapinopyridione (12.3 mg l(-1)), whereas strain D-54 isolated from the same cypress species was low producer (1.1 mg l(-1)); strain D-50 isolated from C. macrocarpa was intermediate producer (5.4 mg l(-1)). Sapinopyridione was characterised by spectroscopic and chemical methods, as the 6-methyl-2-(2-methyl-1-oxobutyl)-1-oxa-5-azaspiro[2.5]oct-6-ene-4,8-dione. The structure was supported by the preparation of three key derivatives, whose phytotoxic and antimycotic activities were also tested on host plants and on three Seiridium species, virulent fungal agents of cypress canker disease. Some structure-activity relationships were identified for both phytoxicity and antifungal activities. These activities appear related to the presence of both pyridione and oxiran rings. Also the carbonyl group of the side chain seems to play a role into impart activity. PMID:16712886

  12. Chemical Emergencies

    MedlinePLUS

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  13. Chemical Peels

    MedlinePLUS

    ... Z Diseases and treatments A - D Chemical peel Chemical peels Also called chemexfoliation , derma peeling Do you ... the cost of cosmetic treatments. Learn more about chemical peels: Is a chemical peel the right choice ...

  14. [Azoles. 18. Sulfonylindazole derivatives].

    PubMed

    Dudzińska-Usarewicz, J; Wrzeciono, U; Frankiewicz, A; Linkowska, E; Köhler, T; Nuhn, P

    1988-09-01

    The nucleophilic substitution of hydrogen to synthesize the sulphonyl indazole derivatives 9-16 is described. The structures of the substitution products are discussed using H-NMR spectra. Chemical structural proof was given by steric hindrance observed in the process of chorination of 9-16. The compounds 3, 4, 7, 8, 14, and 16 are studied to find an inhibition on phospholipase-A2 and lipoxygenase-I. PMID:3149748

  15. Derivative chameleons

    SciTech Connect

    Noller, Johannes

    2012-07-01

    We consider generalized chameleon models where the conformal coupling between matter and gravitational geometries is not only a function of the chameleon field φ, but also of its derivatives via higher order co-ordinate invariants (such as ∂{sub μ}φ∂{sup μ}φ,□φ,...). Specifically we consider the first such non-trivial conformal factor A(φ,∂{sub μ}φ∂{sup μ}φ). The associated phenomenology is investigated and we show that such theories have a new generic mass-altering mechanism, potentially assisting the generation of a sufficiently large chameleon mass in dense environments. The most general effective potential is derived for such derivative chameleon setups and explicit examples are given. Interestingly this points us to the existence of a purely derivative chameleon protected by a shift symmetry for φ → φ+c. We also discuss potential ghost-like instabilities associated with mass-lifting mechanisms and find another, mass-lowering and instability-free, branch of solutions. This suggests that, barring fine-tuning, stable derivative models are in fact typically anti-chameleons that suppress the field's mass in dense environments. Furthermore we investigate modifications to the thin-shell regime and prove a no-go theorem for chameleon effects in non-conformal geometries of the disformal type.

  16. 40 CFR 721.1820 - Bisphenol derivative.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Bisphenol derivative. 721.1820 Section 721.1820 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.1820 Bisphenol derivative....

  17. Complex derivatives

    NASA Astrophysics Data System (ADS)

    Battiston, Stefano; Caldarelli, Guido; Georg, Co-Pierre; May, Robert; Stiglitz, Joseph

    2013-03-01

    The intrinsic complexity of the financial derivatives market has emerged as both an incentive to engage in it, and a key source of its inherent instability. Regulators now faced with the challenge of taming this beast may find inspiration in the budding science of complex systems.

  18. LLNL Chemical Kinetics Modeling Group

    SciTech Connect

    Pitz, W J; Westbrook, C K; Mehl, M; Herbinet, O; Curran, H J; Silke, E J

    2008-09-24

    The LLNL chemical kinetics modeling group has been responsible for much progress in the development of chemical kinetic models for practical fuels. The group began its work in the early 1970s, developing chemical kinetic models for methane, ethane, ethanol and halogenated inhibitors. Most recently, it has been developing chemical kinetic models for large n-alkanes, cycloalkanes, hexenes, and large methyl esters. These component models are needed to represent gasoline, diesel, jet, and oil-sand-derived fuels.

  19. Semisynthetic Derivatives of Epothilones

    NASA Astrophysics Data System (ADS)

    Altmann, Karl-Heinz

    Semisynthetic derivatives of natural products traditionally occupy a prominent space in natural-product-based drug discovery (1, 2). As many biologically active natural products exhibit a high degree of structural complexity (3), the chemical derivatization of material isolated from natural sources often represents the only feasible means (or at least the only economically viable approach) to explore structure-activity-relationships (SAR) and to produce analogs with more favorable pharmacokinetic and pharmacological properties than the natural product lead. Examples of clinically important drugs that are semisynthetic derivatives of natural products exist in virtually all disease areas (1, 2); in the treatment of cancer this includes compounds such as etoposide or teniposide (derived from podophyllotoxin) (4-6), irinotecan and topotecan (derived from camptothecin) (7-9), or docetaxel (derived from 10-deacetylbaccatin III) (10, 11). Even for taxol (11), which is a natural product (12), the sustained supply of sufficient quantities of material for widespread clinical use could only be secured through the development of a semisynthetic production process from another natural product, namely, 10-deacetylbaccatin III (13). In light of these facts, it is not surprising that semisynthesis approaches have also featured prominently in the elucidation of the SAR for epothilones and in the discovery of a number of clinical development candidates.

  20. The chemical juggernaut.

    PubMed

    Cadbury, D

    1997-01-01

    Man-made chemicals pervade and support every aspect of modern living. The chemical industry has become such a powerful force in the global economy, sales of synthetic chemicals and products derived from them constitute well in excess of a third of the world's gross national product. But, these man-made chemicals are also 'elixirs of death,' the symbol of human destruction. Laboratory tests have shown that a number of chemicals in common use possess a remarkable property: they can weakly mimic or modify the action of human hormones. It has been proven that some chemicals found in plastics, pesticides, and industrial products are weakly estrogenic, modifying the action of the female hormone. In addition, other chemicals affect the male hormones, androgens, or anti-androgens; others are thought to target different hormone systems, such as thyroid and adrenal glands. Many research studies are being conducted to establish the impact of chemicals on human health. Of special concern are the rising incidence of testicular cancer, decline in human sperm counts, and the sharp rise of breast cancer. In conclusion, although there is a worldwide debate on the effects of chemical exposure on humans, the significance of findings for human health, concerning testicular and breast cancer, are still unknown. An international treaty is called for to control the use of the persistent hormonally active chemicals. PMID:12321044

  1. Biomass, Chemicals from

    SciTech Connect

    Elliott, Douglas C.

    2004-03-15

    This chapter describes the use and potential use of biomass resources for chemical production as a means to displace petroleum use. Therefore, the scope of the discussion is limited to large scale, commodity chemical products that can have an impact on the energy market by displacing petroleum conversion to chemical products. This article does not address in detail specialty chemical products whose limited market would have minimal impact on energy markets; nor does it describe in detail the use of biomass for material products such as cellulosic fiber for paper or lignocellulosic material for construction materials. The use of biomass for production of a vast array of specialty chemicals based on unique biochemical structures is another part of the overall concept of a sustainable economy, but is outside the scope of this article. Chemical production from biomass is an energy issue in that biomass-derived chemicals can result in a significant impact on the petroleum requirement for petrochemicals used in modern society. Petroleum thus displaced is available for use in the energy market. Petroleum utilization for chemicals production is reported at 14% of the petroleum market in the United States. Displacement of a significant fraction of this chemical synthesis from petroleum can provide an important impact on the overall market. In 1998 the U.S. Department of Energy stated as its goal the production of at least 10% of the basic chemical building blocks from plant-derived renewables by the year 2020 (a five-fold increase) and 50% by 2050 (another five-fold increase). In the long run, utilization of renewable carbon sources for the chemical requirements of society is the only option as fossil sources become more scarce.

  2. Fullerene Derivatives for Medical Applications

    NASA Astrophysics Data System (ADS)

    Hirsch, Andreas

    2005-09-01

    Water-soluble fullerene derivatives have a potential for a variety of medical applications. This is due to the unique structural-, electronic and chemical properties of the fullerene core. The biological properties of suitably functionalized fullerenes range from enzyme inhibition/receptor binding, anticancer and antiviral activity, cell signalling, DNA- and genomic applications, photodynamic activation and most importantly antioxidant properties. This review focusses on the anti-HIV and antioxidant properties of a couple of water soluble fullerene derivatives.

  3. Chemical Microsensors For Detection Of Explosives And Chemical Warfare Agents

    DOEpatents

    Yang, Xiaoguang (Los Alamos, NM); Swanson, Basil I. (Los Alamos, NM)

    2001-11-13

    An article of manufacture is provided including a substrate having an oxide surface layer and a layer of a cyclodextrin derivative chemically bonded to said substrate, said layer of a cyclodextrin derivative adapted for the inclusion of selected compounds, e.g., nitro-containing organic compounds, therewith. Such an article can be a chemical microsensor capable of detecting a resultant mass change from inclusion of the nitro-containing organic compound.

  4. An Elementary Discussion of Chemical Equilibrium.

    ERIC Educational Resources Information Center

    David, Carl W.

    1988-01-01

    This discussion uses a more difficult reaction as the prototype to derive the standard equation for chemical equilibrium. It can be used by students who can understand and use partial derivatives. (CW)

  5. Chemical Specific Adjustment factors Workshop

    EPA Science Inventory

    The World Health Organization, through the International Programme on Chemical Safety (IPCS), has established guidance on the use of mechanistic data to replace default uncertainty factors for interspecies extrapolation and intraspecies variability in deriving risk values such as...

  6. 40 CFR 721.10317 - Alkyl phosphate derivative (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkyl phosphate derivative (generic... Specific Chemical Substances § 721.10317 Alkyl phosphate derivative (generic). (a) Chemical substance and... phosphate derivative (PMN P-02-1040) is subject to reporting under this section for the significant new...

  7. 40 CFR 721.10317 - Alkyl phosphate derivative (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkyl phosphate derivative (generic... Specific Chemical Substances § 721.10317 Alkyl phosphate derivative (generic). (a) Chemical substance and... phosphate derivative (PMN P-02-1040) is subject to reporting under this section for the significant new...

  8. 40 CFR 721.10317 - Alkyl phosphate derivative (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkyl phosphate derivative (generic... Specific Chemical Substances § 721.10317 Alkyl phosphate derivative (generic). (a) Chemical substance and... phosphate derivative (PMN P-02-1040) is subject to reporting under this section for the significant new...

  9. Chemical Emergencies

    MedlinePLUS

    ... happen underground, on railways or highways, and at manufacturing plants. They may involve fire or explosion, or ... of chemicals as only those substances used in manufacturing processes. But chemicals are found everywhere–in our ...

  10. Chemical sensor

    NASA Technical Reports Server (NTRS)

    Rauh, R. David (Inventor)

    1990-01-01

    A sensor for detecting a chemical substance includes an insertion element having a structure which enables insertion of the chemical substance with a resulting change in the bulk electrical characteristics of the insertion element under conditions sufficient to permit effective insertion; the change in the bulk electrical characteristics of the insertion element is detected as an indication of the presence of the chemical substance.

  11. Chemical biology of abscisic acid.

    PubMed

    Kitahata, Nobutaka; Asami, Tadao

    2011-07-01

    Chemical biology is a discipline that utilizes chemicals to elucidate biological mechanisms and physiological functions. Various abscisic acid (ABA) derivatives have revealed the structural requirement for the perception by ABA receptors while biotin or caged derivatives of ABA have disclosed the localization of several ABA-binding proteins. Recently, selective ABA agonist has been used to identify ABA receptors. Furthermore, ABA biosynthesis and catabolic inhibitors have contributed to the identification of new ABA functions in plant growth and development. The physiological function of ABA in non-plant organisms has gradually been revealed. In this review, we discuss the development of small bioactive chemicals and their significance in ABA research. PMID:21461661

  12. Synthesis and characterization of lithium molybdenum selenide nanowires for chemical sensing applications and of nanosheets derived from potassium tetratitanate, potassium calcium niobate, and potassium niobate for photocatalytic water splitting

    NASA Astrophysics Data System (ADS)

    Allen, Mark Ryan

    This work describes both the fabrication of LiMo3Se3 nanowire films and assessment their ability to detect analytes in aqueous solution, and the construction of layered photocatalysts, including heterojunction multicomponent materials, from K2Ti4O9, KCa 2Nb3O10, and K4Nb6O 17 nanosheets, and the characterization of these for their photocatalytic water splitting properties. The LiMo3Se3 nanowire film sensors were conceived by drop-coating a 0.05% (mass) aqueous nanowire solution onto microfabricated indium tin oxide electrode pairs. According to scanning electron microscopy (SEM) and atomic force microscopy (AFM), the films are made of a dense network of 3-7 nm thick nanowire bundles. Immersion of the films in 1.0 M aqueous solutions of group 1 or 2 metal halides or of Zn(II), Mn(II), Fe(II), or Co(II) chlorides results in an increase of the electrical resistance of the films. The resistance change is always positive and reaches up to 9% of the base resistance of the films. It occurs over the course of 30-240 s, and it is reversible for monovalent ions and partially reversible for divalent ions. The signal depends on the concentration of the electrolyte and on the size and charge of the metal cation. Anions do not play a significant role, presumably because they are repelled by the negatively charged nanowire strands. The magnitude of the electrical response and its sign suggest that it is due to analyte-induced scattering of conduction electrons in the nanowires. An ion-induced field effect can be excluded based on gated conductance measurements of the nanowire films. The tetratitanate K2Ti4O9 has been known as a photocatalyst for the oxidation of methanol under UV irradiation. Here we study the evolution of the morphological, optical, and photocatalytic properties of this titanate as it is converted into H2Ti4O 9 and subsequently exfoliated into individual tetrabutylammonium (TBA)-supported [Ti4O9]-2 nanosheets. We find that proton exchange and exfoliation are accompanied by a red shift of the optical absorption edge and fluorescence maximum, suggesting a reduction of the bandgap in the series K2Ti4O9 (3.54 eV), H2Ti 4O9 (3.25 eV), (TBA)2[Ti4O9] (3.00 eV). Neither compound is active for photochemical water splitting, even after photochemical deposition of platinum nanoparticles. However, in aqueous methanol, all platinated compounds are moderately active for H2 evolution upon bandgap irradiation, and in 0.01 M AgNO3, they all produce moderate quantities of O2. From the onset potentials for photoelectrochemical methanol oxidation, the values for the valence band edges at pH 7 are deduced to be lie between -0.23 and -0.53 V (NHE) for the non-platinated compounds, and at +0.08 V and -0.30 V for the platinated compounds. This Pt-induced decrease of negative charge on the titanates is likely due to Fermi level equilibration of metal and semiconductor. Its effect can also be seen in a shift of the onset potentials for electrochemical water oxidation, as measured by cyclic voltammetry. Transient absorption data reveal that photogenerated electrons are trapped in mid band gap states, from which they decay exponentially with a time-constant of 43.67 +/- 0.28 ms, much slower than observed for 68 +/- 1 ns for TiO2 nanocrystals (Degussa, P25). Heterojunction multicomponent photocatalysts have been shown to possess enhanced charge separation upon photoexcitation. Nanostructured heterojunctions were prepared through soft chemical routes from nanosheets derived from the parent vi compounds K2Ti4O9, KCa2Nb 3O10, and K4Nb6O17. Five composites in total, consisting of either one or two types of nanosheets, were synthesized by precipitation of the precursor nanosheets with KOH. Resultant stacked materials were confirmed with transmission electron microscopy and characterized via powder x-ray diffraction. The layered catalysts were found to be inactive for photocatalytic water splitting under illumination of ultraviolet light. However, when irradiated in aqueous methanol, all five materials did yield substantial amounts of H2 gas. Photochem

  13. [Chemical weapons and chemical terrorism].

    PubMed

    Nakamura, Katsumi

    2005-10-01

    Chemical Weapons are kind of Weapons of Mass Destruction (WMD). They were used large quantities in WWI. Historically, large quantities usage like WWI was not recorded, but small usage has appeared now and then. Chemical weapons are so called "Nuclear weapon for poor countrys" because it's very easy to produce/possession being possible. They are categorized (1) Nerve Agents, (2) Blister Agents, (3) Cyanide (blood) Agents, (4) Pulmonary Agents, (5) Incapacitating Agents (6) Tear Agents from the viewpoint of human body interaction. In 1997 the Chemical Weapons Convention has taken effect. It prohibits chemical weapons development/production, and Organization for the Prohibition of Chemical Weapons (OPCW) verification regime contributes to the chemical weapons disposal. But possibility of possession/use of weapons of mass destruction by terrorist group represented in one by Matsumoto and Tokyo Subway Sarin Attack, So new chemical terrorism countermeasures are necessary. PMID:16296384

  14. Chemical sensors

    DOEpatents

    Lowell, Jr., James R. (Bend, OR); Edlund, David J. (Bend, OR); Friesen, Dwayne T. (Bend, OR); Rayfield, George W. (Bend, OR)

    1991-01-01

    Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising (a) a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, operatively coupled to (b) a transducer capable of directly converting said expansion or contraction to a measurable electrical response.

  15. Chemical preconcentrator

    DOEpatents

    Manginell, Ronald P.; Frye-Mason, Gregory C.

    2001-01-01

    A chemical preconcentrator is disclosed with applications to chemical sensing and analysis. The preconcentrator can be formed by depositing a resistive heating element (e.g. platinum) over a membrane (e.g. silicon nitride) suspended above a substrate. A coating of a sorptive material (e.g. a microporous hydrophobic sol-gel coating or a polymer coating) is formed on the suspended membrane proximate to the heating element to selective sorb one or more chemical species of interest over a time period, thereby concentrating the chemical species in the sorptive material. Upon heating the sorptive material with the resistive heating element, the sorbed chemical species are released for detection and analysis in a relatively high concentration and over a relatively short time period. The sorptive material can be made to selectively sorb particular chemical species of interest while not substantially sorbing other chemical species not of interest. The present invention has applications for use in forming high-sensitivity, rapid-response miniaturized chemical analysis systems (e.g. a "chem lab on a chip").

  16. Chemical sensors

    DOEpatents

    Lowell, J.R. Jr.; Edlund, D.J.; Friesen, D.T.; Rayfield, G.W.

    1991-07-02

    Sensors responsive to small changes in the concentration of chemical species are disclosed. The sensors comprise a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment. They are operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical response. 9 figures.

  17. Unnecessary Chemicals

    ERIC Educational Resources Information Center

    Johnson, Anita

    1978-01-01

    Discusses the health hazards resulting from chemical additions of many common products such as cough syrups, food dyes, and cosmetics. Steps being taken to protect consumers from these health hazards are included. (MDR)

  18. Chemical sensors

    DOEpatents

    Lowell, Jr., James R. (Bend, OR); Edlund, David J. (Bend, OR); Friesen, Dwayne T. (Bend, OR); Rayfield, George W. (Eugene, OR)

    1992-01-01

    Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising a mechanicochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, either operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical or optical response, or adhered to a second inert polymeric strip, or doped with a conductive material.

  19. Chemical sensors

    DOEpatents

    Lowell, J.R. Jr.; Edlund, D.J.; Friesen, D.T.; Rayfield, G.W.

    1992-06-09

    Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising a mechanicochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, either operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical or optical response, or adhered to a second inert polymeric strip, or doped with a conductive material. 12 figs.

  20. Drug laws and the 'derivative' problem.

    PubMed

    King, Leslie A; Ujváry, István; Brandt, Simon D

    2014-01-01

    The concept of a 'derivative' is used widely in chemistry, where its precise meaning depends on the circumstances. However, numerous examples of derivative also occur in domestic drugs legislation, some of which stem from the 1961 United Nations Single Convention on Narcotic Drugs. There is a commonly held view that only 'first-order' derivatives should be considered: substances that can be created from a parent structure in a single chemical reaction. In other words, 'derivatives of derivatives' are excluded. However, some substances related to ecgonine (e.g. 2-carbomethoxytropinone) are clearly convertible to cocaine, even though this may require more than one reaction step. It follows that 2-carbomethoxytropinone is a controlled drug, a situation that most chemists would regard as perverse. A more extreme example of the complexity of 'derivative' is shown by the conversion of thebaine to buprenorphine. Even though this requires six or more stages, the US Drug Enforcement Administration successfully argued in a 1986 case that for the purposes of the Controlled Substances Act, the number of steps required was irrelevant; buprenorphine was a derivative of thebaine. Because the term derivative is rarely defined in statutes, the legal status of some substances, such as 2-bromo-LSD, is uncertain. Although a number of definitions of derivative can be found in the chemical literature, no single definition is adequate to describe all situations where it occurs in legislation. Unless qualified, it is suggested that the term derivative should be avoided in any future legislation. PMID:23949903

  1. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid derivative (generic name). 721.6097 Section 721.6097 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical...

  2. 40 CFR 721.10328 - Salt of polyalkylenepolyamine derivative (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Salt of polyalkylenepolyamine... Specific Chemical Substances 721.10328 Salt of polyalkylenepolyamine derivative (generic). (a) Chemical... as salt of polyalkylenepolyamine derivative (PMN P-03-530) is subject to reporting under this...

  3. 40 CFR 721.10328 - Salt of polyalkylenepolyamine derivative (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Salt of polyalkylenepolyamine... Specific Chemical Substances 721.10328 Salt of polyalkylenepolyamine derivative (generic). (a) Chemical... as salt of polyalkylenepolyamine derivative (PMN P-03-530) is subject to reporting under this...

  4. 40 CFR 721.10328 - Salt of polyalkylenepolyamine derivative (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Salt of polyalkylenepolyamine... Specific Chemical Substances 721.10328 Salt of polyalkylenepolyamine derivative (generic). (a) Chemical... as salt of polyalkylenepolyamine derivative (PMN P-03-530) is subject to reporting under this...

  5. Chemical sensors

    SciTech Connect

    Hubbard, C.W.; Gordon, R.L.

    1987-05-01

    The revolution in analytical chemistry promised by recent developments in the field of chemical sensors has potential for significant positive impact on both research and production activities conducted by and for the Department of Energy. Analyses which were, in the past, performed only with a roomful of expensive equipment can now be performed with miniature solid-state electronic devices or small optical probes. Progress in the development of chemical sensors has been rapid, and the field is currently growing at a great rate. In accordance, Pacific Northwest Laboratory initiated a survey of recent literature so that contributors to active programs in research on analytical methods could be made aware of principles and applications of this new technology. This report presents the results of that survey. The sensors discussed here are divided into three types: micro solid-state devices, optical sensors, and piezoelectric crystal devices. The report is divided into three corresponding sections. The first section, ''Micro Solid-State Devices,'' discusses the design, operation, and application of electronic sensors that are produced in much the same way as standard solid-state electronic devices. The second section, ''Optrodes,'' covers the design and operation of chemical sensors that use fiber optics to detect chemically induced changes in optical properties. The final section, ''Piezoelectric Crystal Detectors,'' discusses two types of chemical sensors that depend on the changes in the properties of an oscillating piezoelectric crystal to detect the presence of certain materials. Advantages and disadvantages of each type of sensor are summarized in each section.

  6. Synthesis, vapor growth, polymerization, and characterization of thin films of novel diacetylene derivatives of pyrrole. The use of computer modeling to predict chemical and optical properties of these diacetylenes and poly(diacetylenes)

    NASA Technical Reports Server (NTRS)

    Paley, M. S.; Frazier, D. O.; Abeledeyem, H.; Mcmanus, S. P.; Zutaut, S. E.

    1992-01-01

    In the present work two diacetylene derivatives of pyrrole which are predicted by semiempirical AM1 calculations to have very different properties, are synthesized; the polymerizability of these diacetylenes in the solid state is determined, and the results are compared to the computer predictions. Diacetylene 1 is novel in that the monomer is a liquid at room temperature; this may allow for the possibility of polymerization in the liquid state as well as the solid state. Thin poly(diacetylene) films are obtained from compound 1 by growing films of the monomer using vapor deposition and polymerizing with UV light; these films are then characterized. Interestingly, while the poly(diacetylene) from 1 does not possess good nonlinear optical properties, the monomer exhibits very good third-order effects (phase conjugation) in solution. Dilute acetone solutions of the monomer 1 give intensity-dependent refractive indices on the order of 10 exp -6 esu; these are 10 exp 6 times better than for CS2.

  7. Chemical networks

    NASA Astrophysics Data System (ADS)

    Thi, Wing-Fai

    2015-09-01

    This chapter discusses the fundamental ideas of how chemical networks are build, their strengths and limitations. The chemical reactions that occur in disks combine the cold phase reactions used to model cold molecular clouds with the hot chemistry applied to planetary atmosphere models. With a general understanding of the different types of reactions that can occur, one can proceed in building a network of chemical reactions and use it to explain the abundance of species seen in disks. One on-going research subject is finding new paths to synthesize species either in the gas-phase or on grain surfaces. Specific formation routes for water or carbon monoxide are discussed in more details. 13th Lecture of the Summer School "Protoplanetary Disks: Theory and Modelling Meet Observations"

  8. Chemical lasers

    NASA Astrophysics Data System (ADS)

    Ablekov, V. K.; Denisov, Iu. N.; Proshkin, V. V.

    1983-08-01

    Recent developments in the theory and application of chemical lasers (CLs) are surveyed in a translation of a book published in Russian in 1980. The laws governing the gas-phase chemical reactions typical of CLs are introduced, the principles of quantum-mechanical description of molecular systems are reviewed, and the kinetics of CL processes are examined. The four general classes of CL are then presented in detail: static-gas, subsonic, supersonic, and detonation CLs. Graphs, diagrams, and drawings of experimental setups are provided.

  9. Chemical Mahjong

    ERIC Educational Resources Information Center

    Cossairt, Travis J.; Grubbs, W. Tandy

    2011-01-01

    An open-access, Web-based mnemonic game is described whereby introductory chemistry knowledge is tested using mahjong solitaire game play. Several tile sets and board layouts are included that are themed upon different chemical topics. Introductory tile sets can be selected that prompt the player to match element names to symbols and metric

  10. Chemical Mahjong

    ERIC Educational Resources Information Center

    Cossairt, Travis J.; Grubbs, W. Tandy

    2011-01-01

    An open-access, Web-based mnemonic game is described whereby introductory chemistry knowledge is tested using mahjong solitaire game play. Several tile sets and board layouts are included that are themed upon different chemical topics. Introductory tile sets can be selected that prompt the player to match element names to symbols and metric…

  11. Chemical Indicators.

    ERIC Educational Resources Information Center

    Prombain, Dorothy R.; And Others

    This science sourcebook was written for intermediate grade teachers to provide guidance in teaching a specially developed unit on chemical indicators. Directions and suggestions for guiding student science activities are given. Some of the activities concern soil testing, crystals, and household powders such as sugar and salt. A list of necessary

  12. Delicious Chemicals.

    ERIC Educational Resources Information Center

    Barry, Dana M.

    This paper presents an approach to chemistry and nutrition that focuses on food items that people consider delicious. Information is organized according to three categories of food chemicals that provide energy to the human body: (1) fats and oils; (2) carbohydrates; and (3) proteins. Minerals, vitamins, and additives are also discussed along with…

  13. Chemical Modification of Polysaccharides

    PubMed Central

    Cumpstey, Ian

    2013-01-01

    This review covers methods for modifying the structures of polysaccharides. The introduction of hydrophobic, acidic, basic, or other functionality into polysaccharide structures can alter the properties of materials based on these substances. The development of chemical methods to achieve this aim is an ongoing area of research that is expected to become more important as the emphasis on using renewable starting materials and sustainable processes increases in the future. The methods covered in this review include ester and ether formation using saccharide oxygen nucleophiles, including enzymatic reactions and aspects of regioselectivity; the introduction of heteroatomic nucleophiles into polysaccharide chains; the oxidation of polysaccharides, including oxidative glycol cleavage, chemical oxidation of primary alcohols to carboxylic acids, and enzymatic oxidation of primary alcohols to aldehydes; reactions of uronic-acid-based polysaccharides; nucleophilic reactions of the amines of chitosan; and the formation of unsaturated polysaccharide derivatives. PMID:24151557

  14. Thermodynamic Derivation of the Equilibrium Distribution Functions of Statistical Mechanics.

    ERIC Educational Resources Information Center

    Stoeckly, Beth

    1979-01-01

    Presents a simplified derivation of the equilibrium distribution functions. The derivation proceeds from the change in the Helmholtz free energy when a particle is added to a system of fixed temperature, volume, and chemical potential. The derivations show the relationship between statistical mechanics and macroscopic thermodynamics. (Author/GA)

  15. Skin permeation of acyl derivatives of stobadine.

    PubMed

    Mjekov, Magdalna; Koprda, Vasil; Bohcik, L'ubor; Bohov, Pavol; Hadgraft, Jonathan; Bezkov, Zelmra; Mjek, Pavol

    2006-01-01

    Stobadine is a model drug with pyridoindole structure with cardioprotective and antioxidant properties. Permeation properties of its acyl derivatives were studied to find a proper prodrug form. The experimental study of transdermal delivery of derivatives was combined with the theoretical approach in which the partition coefficients of substances were estimated by means of fragmentation or quantum chemical calculations. All modes applied showed differences in the transport properties of derivative S1 (N-acetyl stobadine). The experimental results obtained for the flux of S1 were higher by one order of magnitude than for the other derivatives and the parent drug. The results are discussed from the point of view of physicochemical properties of derivatives. We concluded that the exceptional permeation value of S1 derivative results from the concurrence of partitioning coefficient, dissociation constant, and arrangement of permeation set. PMID:16401593

  16. CHEMICALS INCORPORATED IN NEST MATERIAL BY RED IMPORTED FIRE ANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Red imported fire ants are believed to incorporate ant-derived chemicals in nesting material. However, only a few chemicals have been identified. One hurdle for such investigation is the interference in chemical analysis from soil-borne chemicals. Ants were found to be able to construct their nes...

  17. Weather Derivative Valuation

    NASA Astrophysics Data System (ADS)

    Jewson, Stephen; Brix, Anders

    2005-04-01

    Weather Derivative Valuation is the first book to cover all the meteorological, statistical, financial and mathematical issues that arise in the pricing and risk management of weather derivatives. There are chapters on meteorological data and data cleaning, the modelling and pricing of single weather derivatives, the modelling and valuation of portfolios, the use of weather and seasonal forecasts in the pricing of weather derivatives, arbitrage pricing for weather derivatives, risk management, and the modelling of temperature, wind and precipitation. Specific issues covered in detail include the analysis of uncertainty in weather derivative pricing, time-series modelling of daily temperatures, the creation and use of probabilistic meteorological forecasts and the derivation of the weather derivative version of the Black-Scholes equation of mathematical finance. Written by consultants who work within the weather derivative industry, this book is packed with practical information and theoretical insight into the world of weather derivative pricing.

  18. Chemical intolerance.

    PubMed

    Dantoft, Thomas M; Andersson, Linus; Nordin, Steven; Skovbjerg, Sine

    2015-01-01

    Chemical intolerance (CI) is a term used to describe a condition in which the sufferer experiences a complex array of recurrent unspecific symptoms attributed to low-level chemical exposure that most people regard as unproblematic. Severe CI constitutes the distinguishing feature of multiple chemical sensitivity (MCS). The symptoms reported by CI subjects are manifold, involving symptoms from multiple organs systems. In severe cases of CI, the condition can cause considerable life-style limitations with severe social, occupational and economic consequences. As no diagnostic tools for CI are available, the presence of the condition can only be established in accordance to criteria definitions. Numerous modes of action have been suggested to explain CI, with the most commonly discussed theories involving the immune system, central nervous system, olfactory and respiratory systems as well as altered metabolic capacity, behavioral conditioning and emotional regulation. However, in spite of more than 50 years of research, there is still a great deal of uncertainties regarding the event(s) and underlying mechanism( s) behind symptom elicitation. As a result, patients are often misdiagnosed or offered health care solutions with limited or no effect, and they experience being met with mistrust and doubt by health care professionals, the social care system and by friends and relatives. Evidence-based treatment options are currently unavailable, however, a person-centered care model based on a multidisciplinary treatment approach and individualized care plans have shown promising results. With this in mind, further research studies and health care solutions should be based on a multifactorial and interdisciplinary approach. PMID:26088215

  19. Inflation Rates, Car Devaluation, and Chemical Kinetics.

    ERIC Educational Resources Information Center

    Pogliani, Lionello; Berberan-Santos, Mario N.

    1996-01-01

    Describes the inflation rate problem and offers an interesting analogy with chemical kinetics. Presents and solves the car devaluation problem as a normal chemical kinetic problem where the order of the rate law and the value of the rate constant are derived. (JRH)

  20. Chemical durability

    SciTech Connect

    Kreuer, K.D.; Warhus, U.

    1986-03-01

    The chemical durability of NASICON (Na/sub 1+x/Zr/sub 2/Si/sub x/P/sub 3-x/O/sub 12/, x=0-3) versus molten sodium and sulfur at 600 K has been investigated. Degradation by molten sodium has been observed for phosphorus-containing compositions only. The pure silicate (x=3), however, appeared to be stable, because reduction of silicon demanded by thermodynamics did not occur at the given temperature for kinetic reasons. The latter composition has also been shown to have good durability against molten sulfur.

  1. ARIANE 5 light derivatives

    NASA Astrophysics Data System (ADS)

    Astorg, Jean-Marc

    1993-01-01

    The Ariane 5 light derivatives are studied in order to complete Ariane 5 launch services with regard to medium size Sun synchronous spacecrafts (S derivative) and small satellites (P derivative). The P derivative is a three stage launcher with two solid propellant motors and a bipropellant upper stage. It is capable of placing 1 ton in a 1000 km circular polar orbit or two 450 kg payloads in the same orbit. The light derivatives are mainly derived from the Ariane 5 solid propellant booster and upper stage. The payload volume is particulary large (2.8 m internal maximal diameter, 6 m height). The light derivatives will be launched from the Ariane spaceport in Guyana. They will use Ariane 5 facilities for payload preparation and launch operation with a specific building for launcher integration. The first flight of the P derivative is scheduled for 1998.

  2. 40 CFR 721.558 - Salt of a fatty alkylamine derivative (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Salt of a fatty alkylamine derivative... Specific Chemical Substances 721.558 Salt of a fatty alkylamine derivative (generic). (a) Chemical... as a salt of a fatty alkylamine derivative (PMN P-96-1426) is subject to reporting under this...

  3. 40 CFR 721.558 - Salt of a fatty alkylamine derivative (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Salt of a fatty alkylamine derivative... Specific Chemical Substances § 721.558 Salt of a fatty alkylamine derivative (generic). (a) Chemical... as a salt of a fatty alkylamine derivative (PMN P-96-1426) is subject to reporting under this...

  4. 40 CFR 721.558 - Salt of a fatty alkylamine derivative (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Salt of a fatty alkylamine derivative... Specific Chemical Substances 721.558 Salt of a fatty alkylamine derivative (generic). (a) Chemical... as a salt of a fatty alkylamine derivative (PMN P-96-1426) is subject to reporting under this...

  5. 40 CFR 721.558 - Salt of a fatty alkylamine derivative (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Salt of a fatty alkylamine derivative... Specific Chemical Substances 721.558 Salt of a fatty alkylamine derivative (generic). (a) Chemical... as a salt of a fatty alkylamine derivative (PMN P-96-1426) is subject to reporting under this...

  6. Deriving Verbs in English

    ERIC Educational Resources Information Center

    Dixon, R. M. W.

    2008-01-01

    Phonological and semantic principles which underlie the derivation of verbs from nouns and adjectives in English are examined. There is intricate phonological conditioning for suffix "-ize" and for suffix "-(i)fy"; a third major process is zero derivation. These derivational processes cover more than a score of semantic relations (some with…

  7. Deriving Verbs in English

    ERIC Educational Resources Information Center

    Dixon, R. M. W.

    2008-01-01

    Phonological and semantic principles which underlie the derivation of verbs from nouns and adjectives in English are examined. There is intricate phonological conditioning for suffix "-ize" and for suffix "-(i)fy"; a third major process is zero derivation. These derivational processes cover more than a score of semantic relations (some with

  8. Chemical Analyses

    NASA Technical Reports Server (NTRS)

    Bulluck, J. W.; Rushing, R. A.

    1994-01-01

    As a preliminary study on the effects of chemical aging of polymer materials MERL and TRI have examined two polymeric materials that are typically used for offshore umbilical applications. These two materials were Tefzel, a copolymer of ethylene and tetrafluoroethylene, and Coflon, polyvinylidene fluoride. The Coflon specimens were cut from pipe sections and exposed to H2S at various temperatures and pressures. One of these specimens was tested for methane permeation, and another for H2S permeation. The Tefzel specimens were cut from .05 mm sheet stock material and were exposed to methanol at elevated temperature and pressure. One of these specimens was exposed to methanol permeation for 2 days at 100 C and 2500 psi. An additional specimen was exposed to liquid methanol for 3 days at 150 C and 15 Bar. Virgin specimens of each material were similarly prepared and tested.

  9. Chemical factors affecting insolubles formation in shale derived diesel fuel

    SciTech Connect

    Beal, E.J.; Mushrush, G.W.; Cooney, J.V. ); Watkins, J.M. )

    1989-01-01

    Detrimental changes in fuel properties with time have been a continuing problem in the use of middle distillate fuels. Instability of diesel fuels is usually defined by the formation of insoluble sediments and gums. Gravimetric stability tests have been conducted at 43/sup 0/ and 80/sup 0/C, respectively, using three model nitrogen heterocycles, 2-methylpyridine, 2,6-di methyl quinoline, and dodecahydrocarbazole, as dopants in an otherwise stable shale diesel fuel. Potential interactive effects have been defined for these three model nitrogen heterocycles in the stable fuel in the presence of a second model dopant, t-butyl hydroperoxide. 2-Methyl pyridine and 2,6-dimethyl quinoline were inactive and only 2-methyl pyridine showed slight positive interactive effects. Dodecahydrocarbazole formed large amounts of insolubles by itself and exhibited positive interactive effects.

  10. Potassium niobate derived from a novel chemical solution

    NASA Astrophysics Data System (ADS)

    Cheng, Z. X.; Ozawa, K.; Miyazaki, A.; Kimura, H.

    2005-02-01

    Potassium niobate (KNbO 3) were successfully prepared by the solution processing through the reaction of aqueous H 2O 2 solution with niobium and potassium alkoxides. In this process, potassium and niobate peroxide formed as the precursor for KNbO 3. Precursor powder crystallized into KNbO 3 at a sintering temperature as low as 650 °C in oxygen. KNbO 3 thin films comprised of uniform grains with dimension of around 100 nm were fabricated.

  11. Quantum chemical assessment of benzimidazole derivatives as corrosion inhibitors

    PubMed Central

    2014-01-01

    Background The majority of well-known inhibitors are organic compounds containing multiple bonds and heteroatoms, such as O, N or S, which allow adsorption onto the metal surface. These compounds can adsorb onto the metal surface and block active surface sites, reducing the rate of corrosion. Results A comparative theoretical study of three benzimidazole isomers, benzimidazole (BI), 2-methylbenzimidazole (2-CH3-BI), and 2-mercaptobenzimidazole (2-SH-BI), as corrosion inhibitors was performed using density functional theory (DFT) with the B3LYP functional basis set. Conclusions Nitro and amino groups were selected for investigation as substituents of the three corrosion inhibitors. Nitration of the corrosion inhibitor molecules led to a decrease in inhibition efficiency, while reduction of the nitro group led to an increase in inhibition efficiency. These aminobenzimidazole isomers represent a significant improvement in the inhibition efficiency of corrosion inhibitor molecules. PMID:24674343

  12. Pyrazine-Derived Disulfide-Reducing Agent for Chemical Biology

    PubMed Central

    Lukesh, John C.; Wallin, Kelly K.

    2014-01-01

    For fifty years, dithiothreitol (DTT) has been the preferred reagent for the reduction of disulfide bonds in proteins and other biomolecules. Herein we report on the synthesis and characterization of 2,3-bis(mercaptomethyl)pyrazine (BMMP), a readily accessible disulfide-reducing agent with reactivity under biological conditions that is markedly superior to DTT and other known reagents. PMID:25014913

  13. Distillation of natural fatty acids and their chemical derivatives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Well over 1,000 different fatty acids are known which are natural components of fats, oils (triacylglycerols), and other related compounds. These fatty acids can have different alkyl chain lengths, 0-6 carbon-carbon double bonds possessing cis- or trans-geometry, and can contain a variety of functio...

  14. The kinetic chemical equilibrium regime

    NASA Astrophysics Data System (ADS)

    Ern, Alexandre; Giovangigli, Vincent

    We investigate reactive gas mixtures in the kinetic chemical equilibrium regime. Our starting point is a generalized Boltzmann equation with a chemical source term valid for arbitrary reaction mechanisms and yielding a positive entropy production. We first study the Enskog expansion in the kinetic chemical equilibrium regime. We derive a new set of macroscopic equations in the zeroth- and first-order regimes, expressing conservation of element densities, momentum and energy. The transport fluxes arising in the Navier-Stokes equilibrium regime are the element diffusion velocities, the heat flux vector and the pressure tensor and are written in terms of transport coefficients. Upon introducing species diffusion velocities, the kinetic equilibrium regime appears to be formally equivalent to the one obtained for gas mixtures in chemical nonequilibrium and then letting the chemical reactions approach equilibrium. The actual values of the transport coefficients are, however, different. Finally, we derive the entropy conservation equation in the Navier-Stokes equilibrium regime and show that the source term is positive and that it is compatible with Onsagers reciprocal relations.

  15. Absolute time derivatives

    NASA Astrophysics Data System (ADS)

    Matolcsi, T.; Vn, P.

    2007-05-01

    A four dimensional treatment of nonrelativistic spacetime gives a natural frame to deal with objective time derivatives. In this framework some well known objective time derivatives of continuum mechanics appear as Lie derivatives. Their coordinatized forms depend on the tensorial properties of the relevant physical quantities. We calculate the particular forms of objective time derivatives for scalars, vectors, covectors, and different second order tensors from the point of view of a rotating observer. The relation of substantial, material, and objective time derivatives is treated.

  16. ASSESSING BIOACCUMULATION FOR DERIVING NATIONAL HUMAN HEALTH WATER QUALITY CRITERIA

    EPA Science Inventory

    The United States Environmental Protection Agency is revising its methodology for deriving national ambient water quality criteria (AWQC) to protect human health. A component of this guidance involves assessing the potential for chemical bioaccumulation in commonly consumed fish ...

  17. Nonlinear response theory in chemical kinetics

    PubMed Central

    Kryvohuz, Maksym; Mukamel, Shaul

    2014-01-01

    A theory of nonlinear response of chemical kinetics, in which multiple perturbations are used to probe the time evolution of nonlinear chemical systems, is developed. Expressions for nonlinear chemical response functions and susceptibilities, which can serve as multidimensional measures of the kinetic pathways and rates, are derived. A new class of multidimensional measures that combine multiple perturbations and measurements is also introduced. Nonlinear fluctuation-dissipation relations for steady-state chemical systems, which replace operations of concentration measurement and perturbations, are proposed. Several applications to the analysis of complex reaction mechanisms are provided. PMID:25669367

  18. Endohedral Metallofullerene Derivatives

    NASA Technical Reports Server (NTRS)

    Dorn, Harry C. (Inventor); Iezzi, Erick B. (Inventor); Duchamp, James (Inventor)

    2008-01-01

    Trimetallic nitride endohedral metallofullerene derivatives and their preparation are described. The trimetallic nitride endohedral metallofullerene derivatives have the general formula A(sub 3-n)X(sub n)@C(sub m)(R) where n ranges from 0 to 3, A and X may be trivalent metals and may be either rare earth metal or group IIIB metals, m is between about 60 and about 200, and R is preferably an organic group. Derivatives where the R group forms cyclized derivatives with the fullerene cage are also described.

  19. [Chemical food contaminants].

    PubMed

    Schrenk, D

    2004-09-01

    Chemical food contaminants are substances which are neither present naturally in the usual raw material used for food production nor are added during the regular production process. Examples are environmental pollutants or contaminants derived from agricultural production of crops or livestock or from inadequate manufacturing of the food product itself. More difficult is the classification of those compounds formed during regular manufacturing such as products of thermal processes including flavoring substances. In these cases, it is common practice to call those compounds contaminants which are known for their adverse effects such as acrylamide, whereas constituents which add to the food-specific flavor such as Maillard products formed during roasting, baking etc. are not termed contaminants. From a toxicological viewpoint this distinction is not always clear-cut. Important groups of chemical contaminants are metals such as mercury or lead, persistent organic pollutants such as polychlorinated biphenyls and related pollutants, which are regularly found in certain types of food originating from background levels of these compounds in our environment. Furthermore, natural toxins form microorganisms or plants, and compounds formed during thermal treatment of food are of major interest. In general, a scientific risk assessment has to be carried out for any known contaminant. This comprises an exposure analysis and a toxicological and epidemiological assessment. On these grounds, regulatory and/or technological measures can often improve the situation. Major conditions for a scientific risk assessment and a successful implementation of regulations are highly developed food quality control, food toxicology and nutritional epidemiology. PMID:15378171

  20. The Chemical Potential

    NASA Astrophysics Data System (ADS)

    Kaplan, Thomas

    2005-03-01

    The definition of the fundamental quantity, the chemical potential (c.p.), is confused in the literature, there being at least three distinct definitions in various books and papers. Major differences among them can occur for finite systems. We resolve the situation by arguing that the chemical potential defined by the symbol μ conventionally appearing in the grand canonical density operator is the uniquely correct definition, the grand canonical ensemble being the only one of the various ensembles usually discussed (microcanonical, canonical, Gibbs, grand canonical) that is appropriate for statistical thermodynamics, whenever the c.p. is physically relevant. The derivation of the zero-temperature limit of this μ for rather general interacting-electron systems by Perdew et. al.,[1] is discussed and extended. The enormous finite-size corrections (in systems >> a cm^3) for one rather common definition of the c.p., found by Shegelski [2] within the standard effective mass model of an ideal intrinsic semiconductor, are discussed. The quantum dot is mentioned as a small-system application. 1. J. F. Perdew et. al., Phys. Rev. Lett. 23, 1691 (1982); J. F. Perdew, in Density-functional methods in Physics, edited by R. M. Dreizler and J. da Providencia, Plenum Press, 1985. 2. M. R. A. Shegelski, Solid State Commun. 38, 351 (1986); Am. J. Phys. 72, 676 (2004).

  1. Cytotoxic dibromotyrosine-derived metabolites from the sponge Aplysina gerardogreeni.

    PubMed

    Hernndez-Guerrero, Claudia J; Zuba, Eva; Ortega, Mara J; Carballo, J Luis

    2007-08-01

    The chemical study of the sponge Aplysina gerardogreeni collected at the Gulf of California has led to the isolation of four new dibromotyrosine-derived metabolites, aplysinones A-D, whose structures were determined by spectroscopic analysis and chemical methods. The new compounds and four semisynthetic analogues prepared in this study have shown cytotoxic activity against human tumor cell lines. PMID:17512741

  2. Azaphilone and Diphenyl Ether Derivatives from a Gorgonian-Derived Strain of the Fungus Penicillium pinophilum.

    PubMed

    Zhao, Dong-Lin; Shao, Chang-Lun; Zhang, Qiang; Wang, Kai-Ling; Guan, Fei-Fei; Shi, Ting; Wang, Chang-Yun

    2015-09-25

    Three new azaphilone derivatives, pinophilins D-F (1-3), and one new diphenyl ether derivative, hydroxypenicillide (10), together with nine known compounds (4-9, 11-13), were isolated from the gorgonian-derived fungus Penicillium pinophilum XS-20090E18. Their structures including absolute configurations were determined by spectroscopic data, chemical conversions, the ECD exciton chirality method, and ECD calculations. Compounds 10-13 exhibited inhibitory activity against the larval settlement of the barnacle Balanus amphitrite at nontoxic concentrations. Compounds 10 and 11 showed cytotoxicity against Hep-2, RD, and HeLa cell lines. PMID:26291474

  3. 40 CFR 721.646 - Aminofluoran derivative (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aminofluoran derivative (generic name). 721.646 Section 721.646 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.646 Aminofluoran derivative (generic name). (a) Chemical substance and significant new...

  4. 40 CFR 721.646 - Aminofluoran derivative (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aminofluoran derivative (generic name). 721.646 Section 721.646 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.646 Aminofluoran derivative (generic name). (a) Chemical substance and significant new...

  5. 40 CFR 721.646 - Aminofluoran derivative (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aminofluoran derivative (generic name). 721.646 Section 721.646 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.646 Aminofluoran derivative (generic name). (a) Chemical substance and significant new...

  6. 40 CFR 721.646 - Aminofluoran derivative (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aminofluoran derivative (generic name). 721.646 Section 721.646 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.646 Aminofluoran derivative (generic name). (a) Chemical substance and significant new...

  7. 40 CFR 721.646 - Aminofluoran derivative (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aminofluoran derivative (generic name). 721.646 Section 721.646 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC... Substances § 721.646 Aminofluoran derivative (generic name). (a) Chemical substance and significant new...

  8. Terpenes from Marine-Derived Fungi

    PubMed Central

    Ebel, Rainer

    2010-01-01

    Terpenes from marine-derived fungi show a pronounced degree of structural diversity, and due to their interesting biological and pharmacological properties many of them have aroused interest from synthetic chemists and the pharmaceutical industry alike. The aim of this paper is to give an overview of the structural diversity of terpenes from marine-derived fungi, highlighting individual examples of chemical structures and placing them in a context of other terpenes of fungal origin. Wherever possible, information regarding the biological activity is presented. PMID:20948911

  9. Renewable Chemicals: Dehydroxylation of Glycerol and Polyols

    PubMed Central

    ten Dam, Jeroen; Hanefeld, Ulf

    2011-01-01

    The production of renewable chemicals is gaining attention over the past few years. The natural resources from which they can be derived in a sustainable way are most abundant in sugars, cellulose and hemicellulose. These highly functionalized molecules need to be de-functionalized in order to be feedstocks for the chemical industry. A fundamentally different approach to chemistry thus becomes necessary, since the traditionally employed oil-based chemicals normally lack functionality. This new chemical toolbox needs to be designed to guarantee the demands of future generations at a reasonable price. The surplus of functionality in sugars and glycerol consists of alcohol groups. To yield suitable renewable chemicals these natural products need to be defunctionalized by means of dehydroxylation. Here we review the possible approaches and evaluate them from a fundamental chemical aspect. PMID:21887771

  10. Mixtures are not derivable

    NASA Astrophysics Data System (ADS)

    Alsina, C.; Schweizer, B.

    1988-06-01

    A binary operation on probability distribution functions is derivable from a binary operation on random variables if there exists a two-place function V such that, for any distribution functions F and G, there exist random variables X and Y, defined on a common probability space, such that F and G are the distribution functions of X and Y , respectively, and ( F, G) is the distribution function of V ( X, Y). We show that if ( F, G) = cF + (1 - c) G, 0 < c < 1, then is not derivable; similarly,? (F,G) = sqrt {FG} is not derivable.

  11. The Chemical Engineer in the Chemical Industry.

    ERIC Educational Resources Information Center

    Zabicky, Jacob

    1986-01-01

    Describes a course for third- or fourth-year chemical engineering students designed to acquaint them with the chemical industry. The course deals with productivity, characteristics of the chemical industry, sources of information, industrial intelligence, research and development, patent law, technology transfer, and quality control. (TW)

  12. The azobenzene derivatives

    NASA Astrophysics Data System (ADS)

    Ionita, Ionica; Radulescu, Cristiana; Poinescu, Aurora Anca; Anghelina, Florina Violeta; Bunghez, Raluca; Ion, Rodica-Mariana

    2015-02-01

    Azobenzene derivatives constitute a group of dyes which have photochromic properties and have been investigated as promising systems for diverse applications in the unconventional optic area, their properties can be moulded with help of light.

  13. Teaching Cournot without Derivatives.

    ERIC Educational Resources Information Center

    Dufwenberg, Martin

    2001-01-01

    Presents a simple technique for teaching the Cournot model to first-year microeconomic students. Involves demonstrating, without the use of derivatives, that out of all rectangles with a common perimeter, the square has the greatest area. (RLH)

  14. Exposure Levels for Chemical Threat Compounds; Information to Facilitate Chemical Incident Response

    SciTech Connect

    Hauschild, Veronique; Watson, Annetta Paule

    2013-01-01

    Exposure Standards, Limits and Guidelines for Chemical Threat Compunds ABSTRACT Exposure criteria for chemical warfare (CW) agents and certain toxic industrial chemicals (TICs) used as CW agents (such as chlorine fill in an improvised explosive device) have been developed for protection of the civilian general public, civilian employees in chemical agent processing facilities and deployed military populations. In addition, compound-specific concentrations have been developed to serve as how clean is clean enough clearance criteria guiding facility recovery following chemical terrorist or other hazardous release events. Such criteria are also useful to verify compound absence, identify containment boundaries and expedite facility recovery following chemical threat release. There is no single right value or concentration appropriate for all chemical hazard control applications. It is acknowledged that locating and comparing the many sources of CW agent and TIC exposure criteria has not been previously well-defined. This paper summarizes many of these estimates and assembles critical documentation regarding their derivation and use.

  15. Microfluidic chemical reaction circuits

    SciTech Connect

    Lee, Chung-cheng; Sui, Guodong; Elizarov, Arkadij; Kolb, Hartmuth C.; Huang, Jiang; Heath, James R.; Phelps, Michael E.; Quake, Stephen R.; Tseng, Hsian-rong; Wyatt, Paul; Daridon, Antoine

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  16. CHEMICAL SAFETY ALERTS-

    EPA Science Inventory

    Chemical Safety Alerts are short publications which explain specific hazards that have become evident through chemical accident investigation efforts. EPA has produced over a dozen Alerts to date. This year's Alert: Managing Chemical Reactivity Hazards

  17. Chemical Growth Regulators for Guayule Plants

    NASA Technical Reports Server (NTRS)

    Dastoor, M. N.; Schubert, W. W.; Petersen, G. R.

    1982-01-01

    Test Tubes containing Guayule - tissue cultures were used in experiments to test effects of chemical-growth regulators. The shoots grew in response to addition of 2-(3,4-dichlorophenoxy)-triethylamine (triethylamine (TEA) derivative) to agar medium. Preliminary results indicate that a class of compounds that promotes growth in soil may also promote growth in a culture medium. Further experiments are needed to define the effect of the TEA derivative.

  18. Chemical Management System

    Energy Science and Technology Software Center (ESTSC)

    1998-10-30

    CMS provides an inventory of all chemicals on order or being held in the laboratory, to provide a specific location for all chemical containers, to ensure that health and safety regulatory codes are being upheld, and to provide PNNL staff with hazardous chemical information to better manage their inventories. CMS is comprised of five major modules: 1) chemical purchasing, 2) chemical inventory, 3) chemical names, properties, and hazard groups, 4) reporting, and 5) system administration.

  19. Nature's chemicals and synthetic chemicals: Comparative toxicology

    SciTech Connect

    Ames, B.N.; Profet, M.; Gold, L.S. )

    1990-10-01

    The toxicology of synthetic chemicals is compared to that of natural chemicals, which represent the vast bulk of the chemicals to which humans are exposed. It is argued that animals have a broad array of inducible general defenses to combat the changing array of toxic chemicals in plant food (nature's pesticides) and that these defenses are effective against both natural and synthetic toxins. Synthetic toxins such as dioxin are compared to natural chemicals, such as indole carbinol (in broccoli) and ethanol. Trade-offs between synthetic and natural pesticides are discussed. The finding that in high-dose tests, a high proportion of both natural and synthetic chemicals are carcinogens, mutagens, teratogens, and clastogens (30-50{percent} for each group) undermines current regulatory efforts to protect public health from synthetic chemicals based on these tests.

  20. [A novel naphthalene derivative from Aloe barbadensis].

    PubMed

    Wu, Xiao-Fang; Wan, Jin-Zhi; Luo, Bing-Jun; Yang, Miao-Rong; Ding, Wen-Jing; Zhong, Jia-Sheng

    2013-05-01

    To investigate the chemical constituents of A. barbadensis, aqueous extract of the plant was subjected to preparative medium pressure liquid chromatography (MPLC). The chemical structures were mainly determined by spectroscopic evidences (UV, IR, HR-MS, 1H NMR, 13C NMR, HSQC, 1H-1H COSY and HMBC) and chemical methods. A new O, O, O-triglucosylated naphthalene derivative, together with two known 6-phenyl-2-pyrone derivatives and four 5-methylchromones, were isolated and identified as 1-((3-((4- O-beta-D-glucopyranosyl)-beta-D-xylopyranosyloxymethyl)-1-hydroxy-8-alpha-L-rhamnopyranosyloxy)naphthalene-2-y])-ethanone (1), 10-O-beta-D-glucopyranosyl aloenin (2), aloenin B (3), aloesin (4), 8-C-glucosyl-(R)-aloesol (5), 8-C-glucosyl-7-O-methyl-(S)-aloesol (6), and isoaloeresin D (7). Compound 1 is a novel naphthalene derivative and named as aloveroside B, compounds 2-3 are isolated from this Aloe species for the first time. PMID:23888696

  1. Dielectric transition of polyacrylonitrile derived carbon nanofibers

    NASA Astrophysics Data System (ADS)

    Li, Jiangling; Su, Shi; Zhou, Lei; Abbot, Andrew M.; Ye, Haitao

    2014-09-01

    The dielectric behavior of polyacrylonitrile derived carbon nanofibers formed at different carbonization temperatures was investigated using impedance spectroscopy. The impedance data are presented in the form of Cole-Cole plots and four equivalent electrical circuits are derived. It is found that by increasing carbonization temperature from 500 to 800 °C, a strong capacitive element in the parallel equivalent circuit is transformed into an inductive element, while the contact resistance and parallel resistance are significantly decreased. Along with the morphological and chemical structural evolution, respectively witnessed by scanning electron microscopy and Raman spectroscopy, the dielectric transition deduced from the transformation of electrical circuits can be correlated to the proposed microstructural changes of polyacrylonitrile derived carbon nanofibers and the interaction/interference among them.

  2. 40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Oxo-substituted amino-al-kanoic acid... Specific Chemical Substances § 721.430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical... as oxo-substituted amino al-kan-oic acid derivative (PMN No. P-92-692) is subject to reporting...

  3. 40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Oxo-substituted amino-al-kanoic acid... Specific Chemical Substances § 721.430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical... as oxo-substituted amino al-kan-oic acid derivative (PMN No. P-92-692) is subject to reporting...

  4. 40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Oxo-substituted amino-al-kanoic acid... Specific Chemical Substances § 721.430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical... as oxo-substituted amino al-kan-oic acid derivative (PMN No. P-92-692) is subject to reporting...

  5. 40 CFR 721.558 - Salt of a fatty alkylamine derivative (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Salt of a fatty alkylamine derivative... Specific Chemical Substances 721.558 Salt of a fatty alkylamine derivative (generic). Link to an... to reporting. (1) The chemical substance identified generically as a salt of a fatty...

  6. Graphene-Based Chemical Sensors.

    PubMed

    Yavari, Fazel; Koratkar, Nikhil

    2012-07-01

    Pioneering research in 2004 by Geim and Novoselov (2010 Nobel Prize winners in Physics) of the University of Manchester led to the isolation of a monolayer graphene sheet. Graphene is a single-atom-thick sheet of sp(2) hybridized carbon atoms that are packed in a hexagonal honeycomb crystalline structure. Graphene is the fundamental building block of all sp(2) carbon materials including single-walled carbon nanotubes, mutliwalled carbon nanotubes, and graphite and is therefore interesting from the fundamental standpoint as well as for practical applications. One of the most promising applications of graphene that has emerged so far is its utilization as an ultrasensitive chemical or gas sensor. In this article, we review some of the significant work performed with graphene and its derivatives for gas detection and provide a perspective on the challenges that need to be overcome to enable commercially viable graphene chemical sensor technologies. PMID:26291854

  7. Olefin recovery via chemical absorption

    SciTech Connect

    Barchas, R.

    1998-06-01

    The recovery of fight olefins in petrochemical plants has generally been accomplished through cryogenic distillation, a process which is very capital and energy intensive. In an effort to simplify the recovery process and reduce its cost, BP Chemicals has developed a chemical absorption technology based on an aqueous silver nitrate solution. Stone & Webster is now marketing, licensing, and engineering the technology. The process is commercially ready for recovering olefins from olefin derivative plant vent gases, such as vents from polyethylene, polypropylene, ethylene oxide, and synthetic ethanol units. The process can also be used to debottleneck C{sub 2} or C{sub 3} splinters, or to improve olefin product purity. This paper presents the olefin recovery imp technology, discusses its applications, and presents economics for the recovery of ethylene and propylene.

  8. CHEMICAL SYNTHESIS OF GLYCOSYLPHOSPHATIDYLINOSITOL ANCHORS

    PubMed Central

    Swarts, Benjamin M.; Guo, Zhongwu

    2013-01-01

    Many eukaryotic cell-surface proteins and glycoproteins are anchored to the plasma membrane by glycosylphosphatidylinositols (GPIs), a family of glycolipids that are post-translationally attached to proteins at their C-termini. GPIs and GPI-anchored proteins play important roles in many biological and pathological events, such as cell recognition and adhesion, signal transduction, host defense, and acting as receptors for viruses and toxins. Chemical synthesis of structurally defined GPI anchors and GPI derivatives is a necessary step toward understanding the properties and functions of these molecules in biological systems and exploring their potential therapeutic applications. In the first part of this comprehensive article on the chemical synthesis of GPIs, classic syntheses of naturally occurring GPI anchors from protozoan parasites, yeast, and mammals are covered. The second part of the article focuses on recent diversity-oriented strategies for the synthesis of GPI anchors containing unsaturated lipids, “click chemistry” tags, and highly branched and modified structures. PMID:22794184

  9. PINS chemical identification software

    DOEpatents

    Caffrey, Augustine J.; Krebs, Kennth M.

    2004-09-14

    An apparatus and method for identifying a chemical compound. A neutron source delivers neutrons into the chemical compound. The nuclei of chemical elements constituting the chemical compound emit gamma rays upon interaction with the neutrons. The gamma rays are characteristic of the chemical elements constituting the chemical compound. A spectrum of the gamma rays is generated having a detection count and an energy scale. The energy scale is calibrated by comparing peaks in the spectrum to energies of pre-selected chemical elements in the spectrum. A least-squares fit completes the calibration. The chemical elements constituting the chemical compound can be readily determined, which then allows for identification of the chemical compound.

  10. Beyond new chemical entities

    PubMed Central

    Caoili, Salvador Eugenio C; Caoili, Salvador Eugenio C

    2014-01-01

    Antibody-type agents (i.e., antibodies and derivatives thereof) may be produced as clinically valuable antidotes, which conceivably could be developed in tandem with prospective new pharmaceutical products so as to render the risks of clinical trials more acceptable from a regulatory standpoint. Yet, this is but a relatively narrow view of the full potential utility associated with antibody-type agents, the significance of which is appreciated upon reconsidering key aspects of early modern biomedical research (notably major contributions thereto by Nobel Laureate Paul Ehrlich) in light of much more recent advances (e.g., application of immunity-oriented approaches to diseases in general, epitope-specific targeting, abzyme-mediated catalysis, antibody-mediated sustained-release buffering of unbound-ligand concentrations, and enhanced thermal and metabolic stability of deuterated chemical species via the kinetic isotope effect), as conditioned by health-related concerns (e.g., current and anticipated epidemiologic transitions vis-a-vis environmental changes) especially with regard to sustainable development (e.g., emphasizing more efficient resource utilization toward increased global resilience based on greater independence from high-maintenance technological infrastructure). The broader view that thus emerges highlights the urgent need to rebalance the health-research agenda, which presently reflect an overemphasis on small-molecule candidate-drug discovery, in order to advance health based on a comprehensive fundamental synthesis of immunity and pharmacology. PMID:24632567

  11. Proton Chemical-Shift Spectra

    NASA Astrophysics Data System (ADS)

    Simova, Svetlana; Sengstschmid, Helmut; Freeman, Ray

    1997-01-01

    Three related methods are explored for obtaining high-resolution proton spectra without spin-spin splittings, termed "chemical-shift spectra." They are based on two-dimensionalJspectroscopy, where theF1dimension is derived by Fourier transformation of spin-echo modulation. The first technique superimposes theJspectrum on its reflection in theF1= 0 axis, creating multiplet patterns in the form of a St. Andrew's cross. The other two techniques purge certain antiphase product-operator terms, either by dispersal in an inhomogeneous effective radiofrequency field oriented at the magic angle (54.7°) or by means of azfilter. In all three cases, the two-dimensional multiplets are separated by means of a symmetry filter and their centers are taken as a measure of the respective chemical shifts. The 400 MHz proton chemical-shift spectrum of 4-androsten-3,17-dione is presented as an illustrative example. Good separation is achieved, even for interpenetrating spin multiplets with near degeneracies in their chemical shifts. Complications due to strong-coupling effects are discussed.

  12. 78 FR 32191 - Derivatives

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-29

    ... alternatives. \\5\\ 71 FR 5155 (February 2, 2012). C. 1998 IRPS This proposed rule is consistent with a 1998... promulgation of this proposed rule. \\7\\ 76 FR 37030 (June 24, 2011). First, the Board asked if it should... derivatives transactions independently. \\9\\ 77 FR 5416 (Feb. 3, 2012). Question One. The Board asked if...

  13. Treatment of biomass to obtain a target chemical

    DOEpatents

    Dunson, Jr., James B. (Newark, DE); Tucker, III, Melvin P. (Lakewood, CO); Elander, Richard T. (Evergreen, CO); Hennessey, Susan Marie (Avondale, PA)

    2010-08-24

    Target chemicals were produced using biocatalysts that are able to ferment sugars derived from treated biomass. Sugars were obtained by pretreating biomass under conditions of high solids and low ammonia concentration, followed by saccharification.

  14. PREDICTION OF OCTANOL/WATER PARTITION COEFFICIENT (KOW) WITH ALGORITHMICALLY DERIVED VARIABLES

    EPA Science Inventory

    A statistical model was developed with algorithmically derived independent variables based on chemical structure for prediction of octanol/water partition coefficients (Kow) measured for more than 4,000 chemicals. he procedure first classified the chemicals into 14 groups based o...

  15. Ionospheric chemical releases

    NASA Technical Reports Server (NTRS)

    Bernhardt, Paul A.; Scales, W. A.

    1990-01-01

    Ionospheric plasma density irregularities can be produced by chemical releases into the upper atmosphere. F-region plasma modification occurs by: (1) chemically enhancing the electron number density; (2) chemically reducing the electron population; or (3) physically convecting the plasma from one region to another. The three processes (production, loss, and transport) determine the effectiveness of ionospheric chemical releases in subtle and surprising ways. Initially, a chemical release produces a localized change in plasma density. Subsequent processes, however, can lead to enhanced transport in chemically modified regions. Ionospheric modifications by chemical releases excites artificial enhancements in airglow intensities by exothermic chemical reactions between the newly created plasma species. Numerical models were developed to describe the creation and evolution of large scale density irregularities and airglow clouds generated by artificial means. Experimental data compares favorably with theses models. It was found that chemical releases produce transient, large amplitude perturbations in electron density which can evolve into fine scale irregularities via nonlinear transport properties.

  16. Revisiting the definition of the electronic chemical potential, chemical hardness, and softness at finite temperatures

    NASA Astrophysics Data System (ADS)

    Franco-Pérez, Marco; Gázquez, José L.; Ayers, Paul W.; Vela, Alberto

    2015-10-01

    We extend the definition of the electronic chemical potential (μe) and chemical hardness (ηe) to finite temperatures by considering a reactive chemical species as a true open system to the exchange of electrons, working exclusively within the framework of the grand canonical ensemble. As in the zero temperature derivation of these descriptors, the response of a chemical reagent to electron-transfer is determined by the response of the (average) electronic energy of the system, and not by intrinsic thermodynamic properties like the chemical potential of the electron-reservoir which is, in general, different from the electronic chemical potential, μe. Although the dependence of the electronic energy on electron number qualitatively resembles the piecewise-continuous straight-line profile for low electronic temperatures (up to ca. 5000 K), the introduction of the temperature as a free variable smoothens this profile, so that derivatives (of all orders) of the average electronic energy with respect to the average electron number exist and can be evaluated analytically. Assuming a three-state ensemble, well-known results for the electronic chemical potential at negative (-I), positive (-A), and zero values of the fractional charge (-(I + A)/2) are recovered. Similarly, in the zero temperature limit, the chemical hardness is formally expressed as a Dirac delta function in the particle number and satisfies the well-known reciprocity relation with the global softness.

  17. Revisiting the definition of the electronic chemical potential, chemical hardness, and softness at finite temperatures.

    PubMed

    Franco-Prez, Marco; Gzquez, Jos L; Ayers, Paul W; Vela, Alberto

    2015-10-21

    We extend the definition of the electronic chemical potential (?e) and chemical hardness (?e) to finite temperatures by considering a reactive chemical species as a true open system to the exchange of electrons, working exclusively within the framework of the grand canonical ensemble. As in the zero temperature derivation of these descriptors, the response of a chemical reagent to electron-transfer is determined by the response of the (average) electronic energy of the system, and not by intrinsic thermodynamic properties like the chemical potential of the electron-reservoir which is, in general, different from the electronic chemical potential, ?e. Although the dependence of the electronic energy on electron number qualitatively resembles the piecewise-continuous straight-line profile for low electronic temperatures (up to ca. 5000 K), the introduction of the temperature as a free variable smoothens this profile, so that derivatives (of all orders) of the average electronic energy with respect to the average electron number exist and can be evaluated analytically. Assuming a three-state ensemble, well-known results for the electronic chemical potential at negative (-I), positive (-A), and zero values of the fractional charge (-(I + A)/2) are recovered. Similarly, in the zero temperature limit, the chemical hardness is formally expressed as a Dirac delta function in the particle number and satisfies the well-known reciprocity relation with the global softness. PMID:26493893

  18. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this...

  19. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this...

  20. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this...

  1. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this...

  2. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this...

  3. 40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (generic). 721.10045... derivative, nickel complex, alkaline salt (generic). (a) Chemical substance and significant new uses subject... heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (PMN P-02-737)...

  4. 40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (generic). 721.10045... derivative, nickel complex, alkaline salt (generic). (a) Chemical substance and significant new uses subject... heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (PMN P-02-737)...

  5. 40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (generic). 721.10045... derivative, nickel complex, alkaline salt (generic). (a) Chemical substance and significant new uses subject... heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (PMN P-02-737)...

  6. 40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (generic). 721.10045... derivative, nickel complex, alkaline salt (generic). (a) Chemical substance and significant new uses subject... heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (PMN P-02-737)...

  7. 40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (generic). 721.10045... derivative, nickel complex, alkaline salt (generic). (a) Chemical substance and significant new uses subject... heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (PMN P-02-737)...

  8. Insulin-derived amyloidosis

    PubMed Central

    Gupta, Yashdeep; Singla, Gaurav; Singla, Rajiv

    2015-01-01

    Amyloidosis is the term for diseases caused by the extracellular deposition of insoluble polymeric protein fibrils in tissues and organs. Insulin-derived amyloidosis is a rare, yet significant complication of insulin therapy. Insulin-derived amyloidosis at injection site can cause poor glycemic control and increased insulin dose requirements because of the impairment in insulin absorption, which reverse on change of injection site and/or excision of the mass. This entity should be considered and assessed by histopathology and immunohistochemistry, in patients with firm/hard local site reactions, which do not regress after cessation of insulin injection at the affected site. Search strategy: PubMed was searched with terms insulin amyloidosis. Full text of articles available in English was reviewed. Relevant cross references were also reviewed. Last search was made on October 15, 2014. PMID:25593849

  9. Derived enriched uranium market

    SciTech Connect

    Rutkowski, E.

    1996-12-01

    The potential impact on the uranium market of highly enriched uranium from nuclear weapons dismantling in the Russian Federation and the USA is analyzed. Uranium supply, conversion, and enrichment factors are outlined for each country; inventories are also listed. The enrichment component and conversion components are expected to cause little disruption to uranium markets. The uranium component of Russian derived enriched uranium hexafluoride is unresolved; US legislation places constraints on its introduction into the US market.

  10. Platform Chemicals from an Oilseed Biorefinery

    SciTech Connect

    Tupy, Mike; Schrodi Yann

    2006-11-06

    The US chemical industry is $460 billion in size where a $150 billion segment of which is non-oxygenated chemicals that is sourced today via petroleum but is addressable by a renewable feedstock if one considers a more chemically reduced feedstock such as vegetable oils. Vegetable oil, due to its chemical functionality, provides a largely untapped opportunity as a renewable chemical source to replace petroleum-derived chemicals and produce platform chemicals unavailable today. This project examined the fertile intersection between the rich building blocks provided by vegetable oils and the enhanced chemical modification capability provided by metathesis chemistry. The technology advanced in this study is the process of ethylene cross-metathesis (referred to as ethenolysis) with vegetable oil and vegetable oil derivatives to manufacture the platform-chemical 9-decenoic acid (or 9DA) and olefin co-products. The project team meet its goals of demonstrating improved catalyst efficiencies of several multiples, deepening the mechanistic understanding of metathesis, synthesis and screening of dozens of new catalysts, designing and modeling commercial processes, and estimating production costs. One demonstrable result of the study was a step change improvement in catalyst turnover number in the ethenolysis of methyl oleate as reported here. We met our key measurable of producing 100 lbs of 9DA at the pilot-scale, which demonstrated ability to scale-up ethenolysis. DOE Project funding had significant positive impact on development of metathetically modified vegetable oils more broadly as the Cargill/Materia partnership, that was able to initiate primarily due to DOE funding, has succeeded in commercializing products, validating metathesis as a platform technology, and expanding a diverse products portfolio in high value and in large volume markets. Opportunities have expanded and business development has gained considerable momentum and enabled further expansion of the Materia/Cargill relationship. This project exceeded expectations and is having immediate impact on DOE success by replacing petroleum products with renewables in a large volume application today.

  11. Satellite-Derived Management Zones

    NASA Technical Reports Server (NTRS)

    Lepoutre, Damien; Layrol, Laurent

    2005-01-01

    The term "satellite-derived management zones" (SAMZ) denotes agricultural management zones that are subdivisions of large fields and that are derived from images of the fields acquired by instruments aboard Earth-orbiting satellites during approximately the past 15 years. "SAMZ" also denotes the methodology and the software that implements the methodology for creating such zones. The SAMZ approach is one of several products of continuing efforts to realize a concept of precision agriculture, which involves optimal variations in seeding, in application of chemicals, and in irrigation, plus decisions to farm or not to farm certain portions of fields, all in an effort to maximize profitability in view of spatial and temporal variations in the growth and health of crops, and in the chemical and physical conditions of soils. As used here, "management zone" signifies, more precisely, a subdivision of a field within which the crop-production behavior is regarded as homogeneous. From the perspective of precision agriculture, management zones are the smallest subdivisions between which the seeding, application of chemicals, and other management parameters are to be varied. In the SAMZ approach, the main sources of data are the archives of satellite imagery that have been collected over the years for diverse purposes. One of the main advantages afforded by the SAMZ approach is that the data in these archives can be reused for purposes of precision agriculture at low cost. De facto, these archives contain information on all sources of variability within a field, including weather, crop types, crop management, soil types, and water drainage patterns. The SAMZ methodology involves the establishment of a Web-based interface based on an algorithm that generates management zones automatically and quickly from archival satellite image data in response to requests from farmers. A farmer can make a request by either uploading data describing a field boundary to the Web site or else drawing the boundary on a reference image. Hence, a farmer can start to engage in precision farming shortly after gaining access to the Web site, without the need for incurring the high costs of conventional precision-agriculture data-collection practices that include collecting soil samples, mapping electrical conductivity of soil, and compiling multiyear crop-yield data. Given the boundary of a field, a SAMZ server computes the zones within the field in a three-stage process. In the first stage, a vector-valued image of the field is constructed by assembling, from the archives, the equivalent of a stack of the available images of the field (see figure). In the second stage, the vector-valued image is analyzed by use of a wavelet transform that detects spatial variations considered significant for precision farming while suppressing small-scale heterogeneities that are regarded as insignificant. In the third stage, a segmentation algorithm assembles the zones from smaller regions that have been identified in the wavelet analysis.

  12. DTP - Chemical Biology Consortium

    Cancer.gov

    Chemical Biology Consortium Home Discovery Development Pathways Grants/Contracts Books/Publications Site Search Data Search What's New Chemical Biology Consortium (CBC) Division of Cancer Treatment and Diagnosis To download Adobe Reader for documents

  13. Chemicals Industry Vision

    SciTech Connect

    none,

    1996-12-01

    Chemical industry leaders articulated a long-term vision for the industry, its markets, and its technology in the groundbreaking 1996 document Technology Vision 2020 - The U.S. Chemical Industry. (PDF 310 KB).

  14. Chemical burn or reaction

    MedlinePLUS

    ... different products that contain toxic chemicals such as ammonia and bleach. The mixture can give off hazardous ... chemicals immediately after use. Use paints, petroleum products, ammonia, bleach, and other products that give off fumes ...

  15. Capacitive chemical sensor

    DOEpatents

    Manginell, Ronald P; Moorman, Matthew W; Wheeler, David R

    2014-05-27

    A microfabricated capacitive chemical sensor can be used as an autonomous chemical sensor or as an analyte-sensitive chemical preconcentrator in a larger microanalytical system. The capacitive chemical sensor detects changes in sensing film dielectric properties, such as the dielectric constant, conductivity, or dimensionality. These changes result from the interaction of a target analyte with the sensing film. This capability provides a low-power, self-heating chemical sensor suitable for remote and unattended sensing applications. The capacitive chemical sensor also enables a smart, analyte-sensitive chemical preconcentrator. After sorption of the sample by the sensing film, the film can be rapidly heated to release the sample for further analysis. Therefore, the capacitive chemical sensor can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

  16. Chemical Industry Bandwidth Study

    SciTech Connect

    none,

    2006-12-01

    The Chemical Bandwidth Study provides a snapshot of potentially recoverable energy losses during chemical manufacturing. The advantage of this study is the use of "exergy" analysis as a tool for pinpointing inefficiencies.

  17. Chemical Transformation Simulator

    EPA Science Inventory

    The Chemical Transformation Simulator (CTS) is a web-based, high-throughput screening tool that automates the calculation and collection of physicochemical properties for an organic chemical of interest and its predicted products resulting from transformations in environmental sy...

  18. Tobacco and chemicals (image)

    MedlinePLUS

    Some of the chemicals associated with tobacco smoke include ammonia, carbon dioxide, carbon monoxide, propane, methane, acetone, hydrogen cyanide and various carcinogens. Other chemicals that are associated with chewing ...

  19. Personal Chemical Exposure informatics

    EPA Science Inventory

    Chemical Exposure science is the study of human contact with chemicals (from manufacturing facilities, everyday products, waste) occurring in their environments and advances knowledge of the mechanisms and dynamics of events that cause or prevent adverse health outcomes. (adapted...

  20. Empirical NMR Chemical Shift Correlations for Methyl and Methylene Protons.

    ERIC Educational Resources Information Center

    Friedrich, Edwin C.; Runkle, Katherine Gates

    1984-01-01

    Presents an internally consistent set of 63 substituent constants developed for use with the Schoolery Relationship to predict the chemical shifts of methylene protons of acyclic compounds. Chemical shift data used in deriving the constants were taken mainly from primary sources of HNMR (nuclear magnetic resonance) spectra. (JN)

  1. 21 CFR 189.120 - Cobaltous salts and its derivatives.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Cobaltous salts and its derivatives. 189.120... Generally Prohibited From Direct Addition or Use as Human Food 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4H6O4, CoCl2, and CoSO4.They have been used in...

  2. 21 CFR 189.120 - Cobaltous salts and its derivatives.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Cobaltous salts and its derivatives. 189.120... Generally Prohibited From Direct Addition or Use as Human Food § 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4H6O4, CoCl2, and CoSO4.They have been used in...

  3. 21 CFR 189.120 - Cobaltous salts and its derivatives.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Cobaltous salts and its derivatives. 189.120... Generally Prohibited From Direct Addition or Use as Human Food 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4H6O4, CoCl2, and CoSO4.They have been used in...

  4. 21 CFR 189.120 - Cobaltous salts and its derivatives.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Cobaltous salts and its derivatives. 189.120... Generally Prohibited From Direct Addition or Use as Human Food 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4H6O4, CoCl2, and CoSO4.They have been used in...

  5. Chemicals: friends and foes.

    PubMed

    Singh, Kirpal

    2014-01-01

    There are many chemicals used in and around homes and workplaces that can result in accidents. Can it be said that the insecticides, drugs, polychlorinated biphenyls, DDT, asbestos, cleansers, cosmetics, and other chemicals are worth the price paid in terms of accidental poisonings? That is for the consumer to decide. Generally, it is the misuse of these chemicals that often leads to tragedy. Chemicals can be dangerous, but they can be advantageous when used with care. PMID:24622781

  6. Computing Equilibrium Chemical Compositions

    NASA Technical Reports Server (NTRS)

    Mcbride, Bonnie J.; Gordon, Sanford

    1995-01-01

    Chemical Equilibrium With Transport Properties, 1993 (CET93) computer program provides data on chemical-equilibrium compositions. Aids calculation of thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93/PC is version of CET93 specifically designed to run within 640K memory limit of MS-DOS operating system. CET93/PC written in FORTRAN.

  7. The elusive chemical potential

    NASA Astrophysics Data System (ADS)

    Baierlein, Ralph

    2001-04-01

    This paper offers some qualitative understanding of the chemical potential, a topic that students invariably find difficult. Three "meanings" for the chemical potential are stated and then supported by analytical development. Two substantial applicationsdepression of the melting point and batteriesillustrate the chemical potential in action. The origin of the term "chemical potential" has its surprises, and a sketch of the history concludes the paper.

  8. AGRICULTURAL CHEMICAL USAGE DATA

    EPA Science Inventory

    This report, which summarizes the use of agricultural chemicals is issued by the National Agricultural Statistics Service (NASS) as part of its series on Agricultural Chemical Usage. Other publications in the series present statistics for on-farm agricultural chemical usage for f...

  9. Chemicals for worldwide aquaculture

    USGS Publications Warehouse

    Schnick, R.A.

    1991-01-01

    Regulations and therapeutants or other safe chemicals that are approved or acceptable for use in the aquaculture industry in the US, Canada, Europe and Japan are presented, discussing also compounds that are unacceptable for aquaculture. Chemical use practices that could affect public health are considered and details given regarding efforts to increase the number of registered and acceptable chemicals.

  10. Toxicology and Chemical Safety.

    ERIC Educational Resources Information Center

    Hall, Stephen K.

    1983-01-01

    Topics addressed in this discussion of toxicology and chemical safety include routes of exposure, dose/response relationships, action of toxic substances, and effects of exposure to chemicals. Specific examples are used to illustrate the principles discussed. Suggests prudence in handling any chemicals, whether or not toxicity is known. (JN)

  11. Naturally occurring chemical carcinogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural products are chemicals found in nature which have unique pharmacological effects. Humans are exposed to many of these bioactive naturally occurring chemicals via the air breathed, the water drunk and the food eaten. Exposure also occurs in clinical settings. Naturally occurring chemicals ...

  12. Chemical and Environmental Technology.

    ERIC Educational Resources Information Center

    Sheather, Harry

    The two-year curriculum in chemical technology presented in the document is designed to prepare high school graduates for technical positions in the chemical industry. Course outlines are given for general chemistry, chemical calculations, quantitative analysis, environmental chemistry, organic chemistry 1 and 2, instrumental analysis, and…

  13. Microreactors for chemical synthesis.

    PubMed

    DeWitt, S H

    1999-06-01

    The advances of the past few years in microreactors have demonstrated that the miniaturization of chemistry has significant advantages with respect to cost, safety, throughput, kinetics and scale-up. The use of chemical microreactors for catalytic oxidations, heterocyclic syntheses and photochemical reactions has illustrated the utility and benefits for both chemical discovery and chemical development applications. PMID:10359719

  14. Thresholds in chemical respiratory sensitisation.

    PubMed

    Cochrane, Stella A; Arts, Josje H E; Ehnes, Colin; Hindle, Stuart; Hollnagel, Heli M; Poole, Alan; Suto, Hidenori; Kimber, Ian

    2015-07-01

    There is a continuing interest in determining whether it is possible to identify thresholds for chemical allergy. Here allergic sensitisation of the respiratory tract by chemicals is considered in this context. This is an important occupational health problem, being associated with rhinitis and asthma, and in addition provides toxicologists and risk assessors with a number of challenges. In common with all forms of allergic disease chemical respiratory allergy develops in two phases. In the first (induction) phase exposure to a chemical allergen (by an appropriate route of exposure) causes immunological priming and sensitisation of the respiratory tract. The second (elicitation) phase is triggered if a sensitised subject is exposed subsequently to the same chemical allergen via inhalation. A secondary immune response will be provoked in the respiratory tract resulting in inflammation and the signs and symptoms of a respiratory hypersensitivity reaction. In this article attention has focused on the identification of threshold values during the acquisition of sensitisation. Current mechanistic understanding of allergy is such that it can be assumed that the development of sensitisation (and also the elicitation of an allergic reaction) is a threshold phenomenon; there will be levels of exposure below which sensitisation will not be acquired. That is, all immune responses, including allergic sensitisation, have threshold requirement for the availability of antigen/allergen, below which a response will fail to develop. The issue addressed here is whether there are methods available or clinical/epidemiological data that permit the identification of such thresholds. This document reviews briefly relevant human studies of occupational asthma, and experimental models that have been developed (or are being developed) for the identification and characterisation of chemical respiratory allergens. The main conclusion drawn is that although there is evidence that the acquisition of sensitisation to chemical respiratory allergens is a dose-related phenomenon, and that thresholds exist, it is frequently difficult to define accurate numerical values for threshold exposure levels. Nevertheless, based on occupational exposure data it may sometimes be possible to derive levels of exposure in the workplace, which are safe. An additional observation is the lack currently of suitable experimental methods for both routine hazard characterisation and the measurement of thresholds, and that such methods are still some way off. Given the current trajectory of toxicology, and the move towards the use of non-animal in vitro and/or in silico) methods, there is a need to consider the development of alternative approaches for the identification and characterisation of respiratory sensitisation hazards, and for risk assessment. PMID:25963507

  15. Thermal luminescence spectroscopy chemical imaging sensor.

    PubMed

    Carrieri, Arthur H; Buican, Tudor N; Roese, Erik S; Sutter, James; Samuels, Alan C

    2012-10-01

    The authors present a pseudo-active chemical imaging sensor model embodying irradiative transient heating, temperature nonequilibrium thermal luminescence spectroscopy, differential hyperspectral imaging, and artificial neural network technologies integrated together. We elaborate on various optimizations, simulations, and animations of the integrated sensor design and apply it to the terrestrial chemical contamination problem, where the interstitial contaminant compounds of detection interest (analytes) comprise liquid chemical warfare agents, their various derivative condensed phase compounds, and other material of a life-threatening nature. The sensor must measure and process a dynamic pattern of absorptive-emissive middle infrared molecular signature spectra of subject analytes to perform its chemical imaging and standoff detection functions successfully. PMID:23033092

  16. Space Derived Air Monitor

    NASA Technical Reports Server (NTRS)

    1983-01-01

    COPAMS, Commonwealth of Pennsylvania Air Monitoring System, derives from technology involved in building unmanned spacecraft. The Nimbus spacecraft carried experimental sensors to measure temperature, pressure, ozone, and water vapor, and instruments for studying solar radiation and telemetry. The process which relayed these findings to Earth formed the basis for COPAMS. The COPAMS system consists of data acquisition units which measure and record pollution level, and sense wind speed and direction, etc. The findings are relayed to a central station where the information is computerized. The system is automatic and supplemented by PAQSS, PA Air Quality Surveillance System.

  17. Microbial chemical factories: recent advances in pathway engineering for synthesis of value added chemicals.

    PubMed

    Dhamankar, Himanshu; Prather, Kristala L J

    2011-08-01

    The dwindling nature of petroleum and other fossil reserves has provided impetus towards microbial synthesis of fuels and value added chemicals from biomass-derived sugars as a renewable resource. Microbes have naturally evolved enzymes and pathways that can convert biomass into hundreds of unique chemical structures, a property that can be effectively exploited for their engineering into Microbial Chemical Factories (MCFs). De novo pathway engineering facilitates expansion of the repertoire of microbially synthesized compounds beyond natural products. In this review, we visit some recent successes in such novel pathway engineering and optimization, with particular emphasis on the selection and engineering of pathway enzymes and balancing of their accessory cofactors. PMID:21601443

  18. Bacterial degradation of chlorophenols and their derivatives

    PubMed Central

    2014-01-01

    Chlorophenols (CPs) and their derivatives are persistent environmental pollutants which are used in the manufacture of dyes, drugs, pesticides and other industrial products. CPs, which include monochlorophenols, polychlorophenols, chloronitrophenols, chloroaminophenols and chloromethylphenols, are highly toxic to living beings due to their carcinogenic, mutagenic and cytotoxic properties. Several physico-chemical and biological methods have been used for removal of CPs from the environment. Bacterial degradation has been considered a cost-effective and eco-friendly method of removing CPs from the environment. Several bacteria that use CPs as their sole carbon and energy sources have been isolated and characterized. Additionally, the metabolic pathways for degradation of CPs have been studied in bacteria and the genes and enzymes involved in the degradation of various CPs have been identified and characterized. This review describes the biochemical and genetic basis of the degradation of CPs and their derivatives. PMID:24589366

  19. Halogenated coumarin derivatives as novel seed protectants.

    PubMed

    Brooker, N; Windorski, J; Bluml, E

    2008-01-01

    Development of new and improved antifungal compounds that are target-specific is backed by a strong Federal, public and commercial mandate. Many plant-derived chemicals have proven fungicidal properties, including the coumarins (1,2-Benzopyrone) found in a variety of plants such as clover, sweet woodruff and grasses. Preliminary research has shown the coumarins to be a highly active group of molecules with a wide range of antimicrobial activity against both fungi and bacteria. It is believed that these cyclic compounds behave as natural pesticidal defence molecules for plants and they represent a starting point for the exploration of new derivative compounds possessing a range of improved antifungal activity. Within this study, derivatives of coumarin that were modified with halogenated side groups were screened for their antifungal activity against a range of soil-borne plant pathogenic fungi. Fungi included in this in vitro screen included Macrophomina phaseolina (charcoal rot), Phytophthora spp. (damping off and seedling rot), Rhizoctonia spp. (damping off and root rot) and Pythium spp. (seedling blight), four phylogenetically diverse and economically important plant pathogens. Studies indicate that these halogenated coumarin derivatives work very effectively in vitro to inhibit fungal growth and some coumarin derivatives have higher antifungal activity and stability as compared to the original coumarin compound alone. The highly active coumarin derivatives are brominated, iodinated and chlorinated compounds and results suggest that besides being highly active, very small amounts can be used to achieve LD100 rates. In addition to the in vitro fungal inhibition assays, results of polymer seed coating compatibility and phytotoxicity testing using these compounds as seed treatments will also be reported. These results support additional research in this area of natural pesticide development. PMID:19226745

  20. Lignin-Derived Advanced Carbon Materials.

    PubMed

    Chatterjee, Sabornie; Saito, Tomonori

    2015-12-01

    Lignin is a highly abundant source of renewable carbon that can be considered as a valuable sustainable source of biobased materials. By applying specific pretreatments and manufacturing methods, lignin can be converted into a variety of value-added carbon materials. However, the physical and chemical heterogeneities of lignin complicate its use as a feedstock. Herein lignin manufacturing process, the effects of pretreatments and manufacturing methods on the properties of product lignin, and structure-property relationships in various applications of lignin-derived carbon materials, such as carbon fibers, carbon mats, activated carbons, carbon films, and templated carbon, are discussed. PMID:26568373

  1. Enveloped virus inactivation by fatty acid derivatives.

    PubMed

    Sands, J A; Auperin, L D; Reinhardt, A

    1979-01-01

    The enveloped bacteriophage phi6 has been shown to be a valuable model system for the preliminary screening of compounds that might be expected to inactivate herpes simplex virus and other enveloped mammalian viruses. A variety of fatty acid derivatives that form fluid micelles in aqueous media have been found to be potent inactivators of phi6. The chemical nature of the polar head group, the length of the alkyl chain(s), and the extent and geometry of unsaturation are all important parameters in determining the antiviral effectiveness of this class of compounds. PMID:218498

  2. Chemical Synthesis of Proteins

    PubMed Central

    Nilsson, Bradley L.; Soellner, Matthew B.; Raines, Ronald T.

    2010-01-01

    Proteins have become accessible targets for chemical synthesis. The basic strategy is to use native chemical ligation, Staudinger ligation, or other orthogonal chemical reactions to couple synthetic peptides. The ligation reactions are compatible with a variety of solvents and proceed in solution or on a solid support. Chemical synthesis enables a level of control on protein composition that greatly exceeds that attainable with ribosome-mediated biosynthesis. Accordingly, the chemical synthesis of proteins is providing previously unattainable insight into the structure and function of proteins. PMID:15869385

  3. Pharmacological characterization of tachykinin tetrabranched derivatives

    PubMed Central

    Ruzza, Chiara; Rizzi, Anna; Malfacini, Davide; Cerlesi, Maria Camilla; Ferrari, Federica; Marzola, Erika; Ambrosio, Caterina; Gro, Cristina; Severo, Salvadori; Costa, Tommaso; Calo, Girolamo; Guerrini, Remo

    2014-01-01

    Background and Purpose Peptide welding technology (PWT) is a novel chemical strategy that allows the synthesis of multibranched peptides with high yield, purity and reproducibility. Using this technique, we have synthesized and pharmacologically characterized the tetrabranched derivatives of the tachykinins, substance P (SP), neurokinin A (NKA) and B (NKB). Experimental Approach The following in vitro assays were used: calcium mobilization in cells expressing human recombinant NK receptors, BRET studies of G-protein NK1 receptor interaction, guinea pig ileum and rat urinary bladder bioassays. Nociceptive behavioural response experiments were performed in mice following intrathecal injection of PWT2-SP. Key Results In calcium mobilization studies, PWT tachykinin derivatives behaved as full agonists at NK receptors with a selectivity profile similar to that of the natural peptides. NK receptor antagonists display similar potency values when tested against PWT2 derivatives and natural peptides. In BRET and bioassay experiments PWT2-SP mimicked the effects of SP with similar potency, maximal effects and sensitivity to aprepitant. After intrathecal administration in mice, PWT2-SP mimicked the nociceptive effects of SP, but with higher potency and a longer-lasting action. Aprepitant counteracted the effects of PWT2-SP?in vivo. Conclusions and Implications The present study has shown that the PWT technology can be successfully applied to the peptide sequence of tachykinins to generate tetrabranched derivatives characterized with a pharmacological profile similar to the native peptides. In vivo, PWT2-SP displayed higher potency and a marked prolongation of action, compared with SP. PMID:24758475

  4. Chemical information based scaling of molecular descriptors: a universal chemical scale for library design and analysis.

    PubMed

    Tounge, Brett A; Pfahler, Lori B; Reynolds, Charles H

    2002-01-01

    Scaling is a difficult issue for any analysis of chemical properties or molecular topology when disparate descriptors are involved. To compare properties across different data sets, a common scale must be defined. Using several publicly available databases (ACD, CMC, MDDR, and NCI) as a basis, we propose to define chemically meaningful scales for a number of molecular properties and topology descriptors. These chemically derived scaling functions have several advantages. First, it is possible to define chemically relevant scales, greatly simplifying similarity and diversity analyses across data sets. Second, this approach provides a convenient method for setting descriptor boundaries that define chemically reasonable topology spaces. For example, descriptors can be scaled so that compounds with little potential for biological activity, bioavailability, or other drug-like characteristics are easily identified as outliers. We have compiled scaling values for 314 molecular descriptors. In addition the 10th and 90th percentile values for each descriptor have been calculated for use in outlier filtering. PMID:12132889

  5. Chemical exchange program analysis.

    SciTech Connect

    Waffelaert, Pascale

    2007-09-01

    As part of its EMS, Sandia performs an annual environmental aspects/impacts analysis. The purpose of this analysis is to identify the environmental aspects associated with Sandia's activities, products, and services and the potential environmental impacts associated with those aspects. Division and environmental programs established objectives and targets based on the environmental aspects associated with their operations. In 2007 the most significant aspect identified was Hazardous Materials (Use and Storage). The objective for Hazardous Materials (Use and Storage) was to improve chemical handling, storage, and on-site movement of hazardous materials. One of the targets supporting this objective was to develop an effective chemical exchange program, making a business case for it in FY07, and fully implementing a comprehensive chemical exchange program in FY08. A Chemical Exchange Program (CEP) team was formed to implement this target. The team consists of representatives from the Chemical Information System (CIS), Pollution Prevention (P2), the HWMF, Procurement and the Environmental Management System (EMS). The CEP Team performed benchmarking and conducted a life-cycle analysis of the current management of chemicals at SNL/NM and compared it to Chemical Exchange alternatives. Those alternatives are as follows: (1) Revive the 'Virtual' Chemical Exchange Program; (2) Re-implement a 'Physical' Chemical Exchange Program using a Chemical Information System; and (3) Transition to a Chemical Management Services System. The analysis and benchmarking study shows that the present management of chemicals at SNL/NM is significantly disjointed and a life-cycle or 'Cradle-to-Grave' approach to chemical management is needed. This approach must consider the purchasing and maintenance costs as well as the cost of ultimate disposal of the chemicals and materials. A chemical exchange is needed as a mechanism to re-apply chemicals on site. This will not only reduce the quantity of unneeded chemicals and the amount spent on new purchases, but will also avoid disposal costs. If SNL/NM were to realize a 5 percent reduction in chemical inventory and a 10 percent reduction in disposal of unused chemicals the total savings would be $189, 200 per year.

  6. Certain legal aspects of derivatives.

    PubMed

    Cloney, T J

    1994-01-01

    This article discusses legal characteristics of derivatives that a not-for-profit health care company may use in a conduit financing in which a governmental issuer issues bonds for the benefit of a health care company. This article also presents the Master Agreement promulgated by the International Swaps and Derivatives Association; discusses how to get out of a derivative; discusses the status of a derivative after insolvency of a counterparty; presents disclosure issues relating to documents prepared in connection with an issue of bonds; and describes the treatment of derivatives under commodities regulations. It concludes with a presentation of possible new regulations applying to derivatives. PMID:7614221

  7. Acquiring Knowledge of Derived Nominals and Derived Adjectives in Context

    ERIC Educational Resources Information Center

    Marinellie, Sally A.; Kneile, Lynn A.

    2012-01-01

    Purpose: This research investigated children's ability to acquire semantic and syntactic knowledge of derived nominals and derived adjectives in the context of short passages. The study also investigated the relation of morphological awareness and the ability to acquire knowledge of derived words in context. Method: A total of 106 children in

  8. Acquiring Knowledge of Derived Nominals and Derived Adjectives in Context

    ERIC Educational Resources Information Center

    Marinellie, Sally A.; Kneile, Lynn A.

    2012-01-01

    Purpose: This research investigated children's ability to acquire semantic and syntactic knowledge of derived nominals and derived adjectives in the context of short passages. The study also investigated the relation of morphological awareness and the ability to acquire knowledge of derived words in context. Method: A total of 106 children in…

  9. Chemical Kinetic Modeling of Advanced Transportation Fuels

    SciTech Connect

    PItz, W J; Westbrook, C K; Herbinet, O

    2009-01-20

    Development of detailed chemical kinetic models for advanced petroleum-based and nonpetroleum based fuels is a difficult challenge because of the hundreds to thousands of different components in these fuels and because some of these fuels contain components that have not been considered in the past. It is important to develop detailed chemical kinetic models for these fuels since the models can be put into engine simulation codes used for optimizing engine design for maximum efficiency and minimal pollutant emissions. For example, these chemistry-enabled engine codes can be used to optimize combustion chamber shape and fuel injection timing. They also allow insight into how the composition of advanced petroleum-based and non-petroleum based fuels affect engine performance characteristics. Additionally, chemical kinetic models can be used separately to interpret important in-cylinder experimental data and gain insight into advanced engine combustion processes such as HCCI and lean burn engines. The objectives are: (1) Develop detailed chemical kinetic reaction models for components of advanced petroleum-based and non-petroleum based fuels. These fuels models include components from vegetable-oil-derived biodiesel, oil-sand derived fuel, alcohol fuels and other advanced bio-based and alternative fuels. (2) Develop detailed chemical kinetic reaction models for mixtures of non-petroleum and petroleum-based components to represent real fuels and lead to efficient reduced combustion models needed for engine modeling codes. (3) Characterize the role of fuel composition on efficiency and pollutant emissions from practical automotive engines.

  10. 6-Bromocholesterol derivatives

    SciTech Connect

    Flanagan, R.J.

    1984-02-07

    Novel 6-bromo derivatives of cholesterol have the formula 3-(R-O-),6-BR,17-((H3C-)2-HC-H2C-H2C-H2C-HC(-CH3)-)-ESTR-5-ENE Such compounds are prepared from the known 6-iodocholesterol by treatment with cuprous bromide. These compounds, labelled with radioisotopes of Br-82 or Br-77, are localized in the adrenal, mammary and ovary tissue of female mammals and in the adrenal or prostate tissue of males when administered to such individuals. This provides a method for imaging adrenal, ovary or prostate tissue which is superior to use of the prior art 6-iodo-cholesterol.

  11. Chemically Prepared Lead Magnesium Niobate Dielectrics

    SciTech Connect

    Tuttle, B.A.; Voigt, J.A.; Sipola, D.L.; Olson, W.R.; Goy, D.M.

    1998-01-01

    A chemical solution powder synthesis technique has been developed that produces fine uniform powders of lead magnesium niobate (PMN) with 60 to 80 nm crystallite size. The synthesis technique was based on the dissolution of lead acetate and alkoxide precursors in acetic acid followed by precipitation with oxalic acid/propanol solutions. Lead magnesium niobate ceramics fabricated from these chemically derived powders had smaller, more uniform grain size and higher dielectric constants than ceramics fabricated from mixed oxide powders that were processed under similar thermal conditions.

  12. Derivative spectrophotometry applied to solutions of complex composition

    SciTech Connect

    Perfil'ev, V.A.

    1986-01-01

    The authors consider not only the basic principles of derivative spectrophotometry but also survey the data on its use in research on the properties of materials, the compositions of compounds, and the structures of complex chemical systems. Recording methods by which derivative spectra can be generated include descriptions of electronic differentiation, computer spectrum differentiation, wavelength modulation, and the two-way derivative method. A section on the advantages of derivative spectrophotometry presents a discussion on features enabling one to determine various substances from their characteristic absorption spectra without performing complicated operations to isolate or separate the components. Other topics include research on the structures of substances and metal-ion complexing in solutions, derivative spectrophotometry in gas analysis, gas determination, and determining organic and compounds.

  13. Pharmacology of endothelium-derived nitric oxide and nitrovasodilators.

    PubMed Central

    Ignarro, L. J.; Ross, G.; Tillisch, J.

    1991-01-01

    Nitric oxide is the active chemical species responsible for the vasodilator action of nitroglycerin, nitroprusside, and related nitrovasodilators. The most potent vasodilator and inhibitor of platelet aggregation known, nitric oxide was recently discovered to occur endogenously as the endothelium-derived relaxing factor. The pharmacology of endothelium-derived nitric oxide is virtually identical to that of the clinically used nitrovasodilators. Although endothelium-derived relaxing factor or endothelium-derived nitric oxide seems to be important in animals, its significance in humans still needs to be shown. We review the recent discoveries in the identification, biosynthesis, metabolism, and biologic actions of endothelium-derived nitric oxide, its significance in humans, and its relation to the clinically used nitrovasodilators. PMID:1902612

  14. Digital and analog chemical evolution.

    PubMed

    Goodwin, Jay T; Mehta, Anil K; Lynn, David G

    2012-12-18

    Living matter is the most elaborate, elegant, and complex hierarchical material known and is consequently the natural target for an ever-expanding scientific and technological effort to unlock and deconvolute its marvelous forms and functions. Our current understanding suggests that biological materials are derived from a bottom-up process, a spontaneous emergence of molecular networks in the course of chemical evolution. Polymer cooperation, so beautifully manifested in the ribosome, appeared in these dynamic networks, and the special physicochemical properties of the nucleic and amino acid polymers made possible the critical threshold for the emergence of extant cellular life. These properties include the precise and geometrically discrete hydrogen bonding patterns that dominate the complementary interactions of nucleic acid base-pairing that guide replication and ensure replication fidelity. In contrast, complex and highly context-dependent sets of intra- and intermolecular interactions guide protein folding. These diverse interactions allow the more analog environmental chemical potential fluctuations to dictate conformational template-directed propagation. When these two different strategies converged in the remarkable synergistic ribonucleoprotein that is the ribosome, this resulting molecular digital-to-analog converter achieved the capacity for both persistent information storage and adaptive responses to an ever-changing environment. The ancestral chemical networks that preceded the Central Dogma of Earth's biology must reflect the dynamic chemical evolutionary landscapes that allowed for selection, propagation, and diversification and ultimately the demarcation and specialization of function that modern biopolymers manifest. Not only should modern biopolymers contain molecular fossils of this earlier age, but it should be possible to use this information to reinvent these dynamic functional networks. In this Account, we review the first dynamic network created by modification of a nucleic acid backbone and show how it has exploited the digital-like base pairing for reversible polymer construction and information transfer. We further review how these lessons have been extended to the complex folding landscapes of templated peptide assembly. These insights have allowed for the construction of molecular hybrids of each biopolymer class and made possible the reimagining of chemical evolution. Such elaboration of biopolymer chimeras has already led to applications in therapeutics and diagnostics, to the construction of novel nanostructured materials, and toward orthogonal biochemical pathways that expand the evolution of existing biochemical systems. The ability to look beyond the primordial emergence of the ribosome may allow us to better define the origins of chemical evolution, to extend its horizons beyond the biology of today and ask whether evolution is an inherent property of matter unbounded by physical limitations imposed by our planet's diverse environments. PMID:23098254

  15. Thermoelastic constitutive equations for chemically hardening materials

    NASA Technical Reports Server (NTRS)

    Shaffer, B. W.; Levitsky, M.

    1974-01-01

    Thermoelastic constitutive equations are derived for a material undergoing solidification or hardening as the result of a chemical reaction. The derivation is based upon a two component model whose composition is determined by the degree of hardening, and makes use of strain-energy considerations. Constitutive equations take the form of stress rate-strain rate relations, in which the coefficients are time-dependent functions of the composition. Specific results are developed for the case of a material of constant bulk modulus which undergoes a transition from an initial liquidlike state into an isotropic elastic solid. Potential applications are discussed.

  16. Relative chemical abundances in different solar regions

    SciTech Connect

    Mariska, J.T.

    1980-01-01

    Intensities of extreme-ultraviolet emmision lines formed in quiet Sun regions, a coronal hole, an active region, and a prominence are used to derived chemical abundances of carbon, nitrogen, and oxygen relative to silicon in each region. For each element the relative abundance in each region agrees to within the estimated errors in the analysis. This means that the relative abundances are constant over a wide range of electron densities, emission measures, turbulent mass motions, and heights above the limb. Uncertainties in the atomic data appear to be the primary source of scatter in the derived abundances.

  17. Experts' understanding of partial derivatives using the partial derivative machine

    NASA Astrophysics Data System (ADS)

    Roundy, David; Weber, Eric; Dray, Tevian; Bajracharya, Rabindra R.; Dorko, Allison; Smith, Emily M.; Manogue, Corinne A.

    2015-12-01

    [This paper is part of the Focused Collection on Upper Division Physics Courses.] Partial derivatives are used in a variety of different ways within physics. Thermodynamics, in particular, uses partial derivatives in ways that students often find especially confusing. We are at the beginning of a study of the teaching of partial derivatives, with a goal of better aligning the teaching of multivariable calculus with the needs of students in STEM disciplines. In this paper, we report on an initial study of expert understanding of partial derivatives across three disciplines: physics, engineering, and mathematics. We report on the central research question of how disciplinary experts understand partial derivatives, and how their concept images of partial derivatives differ, with a focus on experimentally measured quantities. Using the partial derivative machine (PDM), we probed expert understanding of partial derivatives in an experimental context without a known functional form. In particular, we investigated which representations were cued by the experts' interactions with the PDM. Whereas the physicists and engineers were quick to use measurements to find a numeric approximation for a derivative, the mathematicians repeatedly returned to speculation as to the functional form; although they were comfortable drawing qualitative conclusions about the system from measurements, they were reluctant to approximate the derivative through measurement. On a theoretical front, we found ways in which existing frameworks for the concept of derivative could be expanded to include numerical approximation.

  18. Spectral Characterization of Plant-Derived Dissolved Organic Matter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved organic matter (DOM) derived from fresh or early-stage decomposing soil amendment materials may play an important role in the process of organic matter accumulation. The DOM can influence many chemical processes, due to its reactivity with both soil solution components and soil surfaces. W...

  19. 40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193 Protection of...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. (a) Chemical substance and...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts (PMN P-06-263, Chemical B; CAS......

  20. 40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193 Protection of...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. (a) Chemical substance and...-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts (PMN P-06-263, Chemical B; CAS......