These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Potential applications for biguanides in oncology  

PubMed Central

Metformin is widely prescribed for the treatment of type II diabetes. Recently, it has been proposed that this compound or related biguanides may have antineoplastic activity. Biguanides may exploit specific metabolic vulnerabilities of transformed cells by acting on them directly, or may act by indirect mechanisms that involve alterations of the host environment. Preclinical data suggest that drug exposure levels are a key determinant of proposed direct actions. With respect to indirect mechanisms, it will be important to determine whether recently demonstrated metformin-induced changes in levels of candidate systemic mediators such as insulin or inflammatory cytokines are of sufficient magnitude to achieve therapeutic benefit. Results of the first generation of clinical trials now in progress are eagerly anticipated. Ongoing investigations may justify a second generation of trials that explore pharmacokinetic optimization, rational drug combinations, synthetic lethality strategies, novel biguanides, and the use of predictive biomarkers. PMID:23999444

Pollak, Michael

2013-01-01

2

The effects of biguanides on thrombokinase, thrombin and trypsin.  

PubMed

A purified preparation of bovine thrombokinase (activated Factor X) loses the ability to hydrolyze TAME (p-toluenesulfonyl-L-arginine methyl ester) when it is incubated at 37 degrees in 0.25 M Tris. HCl buffer, pH 7.4 with lauroxypropyl biguanide, N1, N5-dimethyl, N1-lauroxypropyl biguanide, N1-p-chlorophenethyl, N5-phenethyl biguanide, or N1-methyl, N1-p-chlorobenzyl, N5-o,p-dichlorobenzyl biguanide. Activity is lost much more slowly when 0.15 M NaCl is also present. Lauroxypropyl biguanide is the most potent of the compounds tested, 0.22 mM causing thrombokinase to lose almost all of its activity in about 30 minutes at 37 degrees in pH 7.4 buffered saline. Topical bovine thrombin also loses activity when incubated with either of the lauroxypropyl biguanides but not with the diphenethyl or the dibenzyl compound. Instead, the latter biguanides accelerate thrombin's hydrolysis of TAME. The percent acceleration is not affected or only slightly decreased by the presence of 0.15 M NaCl or KCl, and it is also unaffected by incubating the enzyme with the compounds in buffered saline for 4 to 120 minutes. Purified bovine trypsin is stabilized by both lauroxypropyl and the diphenethyl biguanide when incubated at 37 degrees in pH 7.4 buffered saline for the 60 minute test period but neither compounds has any effect on its rate of hydrolysis of TAME. It is postulated that the enzymes first react rapidly and reversibly with all of the test biguanides and, depending upon the enzyme and the substrate, the rate of hydrolysis of the substrate is unaffected, accelerated or inhibited. The lauroxypropyl biguanides also undergo a second, slower reaction with both thrombokinase and thrombin that produces loss of enzymatic activity. The dibenzyl and diphenethyl biguanides also undergo this second slow reaction with thrombokinase but not with thrombin, and none of the biguanides undergo this second reaction with trypsin. PMID:242090

Roberts, P S; Fleming, P B

1975-09-30

3

Effects of metformin and other biguanides on oxidative phosphorylation in mitochondria.  

PubMed

The biguanide metformin is widely prescribed for Type II diabetes and has anti-neoplastic activity in laboratory models. Despite evidence that inhibition of mitochondrial respiratory complex I by metformin is the primary cause of its cell-lineage-specific actions and therapeutic effects, the molecular interaction(s) between metformin and complex I remain uncharacterized. In the present paper, we describe the effects of five pharmacologically relevant biguanides on oxidative phosphorylation in mammalian mitochondria. We report that biguanides inhibit complex I by inhibiting ubiquinone reduction (but not competitively) and, independently, stimulate reactive oxygen species production by the complex I flavin. Biguanides also inhibit mitochondrial ATP synthase, and two of them inhibit only ATP hydrolysis, not synthesis. Thus we identify biguanides as a new class of complex I and ATP synthase inhibitor. By comparing biguanide effects on isolated complex I and cultured cells, we distinguish three anti-diabetic and potentially anti-neoplastic biguanides (metformin, buformin and phenformin) from two anti-malarial biguanides (cycloguanil and proguanil): the former are accumulated into mammalian mitochondria and affect oxidative phosphorylation, whereas the latter are excluded so act only on the parasite. Our mechanistic and pharmacokinetic insights are relevant to understanding and developing the role of biguanides in new and existing therapeutic applications, including cancer, diabetes and malaria. PMID:25017630

Bridges, Hannah R; Jones, Andrew J Y; Pollak, Michael N; Hirst, Judy

2014-09-15

4

Incidence of severe sideeffects during therapy with sulfonylureas and biguanides.  

PubMed

The most important side-effect of sulfonylureas is hypoglycaemia. According to surveys in Switzerland and in Sweden it occurs at a frequency of about 2 cases per 10,000 treatment years. Mortality is high, about 10%. The syndrome of inappropriate ADH-secretion has been observed almost exclusively during treatment with chlorpropamide. Asymptomatic cases of SIADH-syndrome are quite frequent, hyponatraemia has been observed in 6-10% of diabetics treated with chlorpropamide. The most dangerous side-effect of biguanides is lactic acidosis. It occurs significantly more frequent during treatment with phenformin compared to metformin. Metformin has been reported to lead to lactic acidosis in 0.4 cases per 10,000 treatment years; mortality is about 30%. Mortality of phenformin-associated lactic acidosis is even higher, 70%. Both biguanides, phenformin and metformin, cause relatively frequently vitamin B12-malabsorption (in about 1/3 of the cases). However, symptomatic vitamin B12-deficiency is extremely rare. PMID:3865878

Berger, W

1985-01-01

5

Double-Biguanide Therapy for Resistant Acanthamoeba Keratitis  

PubMed Central

Aims To report the clinical and diagnostic findings of a patient with Acanthamoeba keratitis resistant to both polyhexamethylene biguanide (PHMB)-hexamidine and chlorhexidine-hexamidine treatment. Methods Slit-lamp biomicroscopy, corneal cell scraping and histopathology were performed on a 39-year-old woman presenting with corneal ulcer in her left eye. Results The patient was successfully treated with PHMB-chlorhexidine association therapy. Subsequent perforating keratoplasty remained clear at the last follow-up visit after 7 months and increased visual acuity to 20/20 with correction. Conclusions This case emphasizes the proteiform aspects of Acanthamoeba drug resistance, and suggests that PHMB-chlorhexidine association might represent an additional option for cases resistant to standard therapy. PMID:22174703

Ferrari, Giulio; Matuska, Stanislav; Rama, Paolo

2011-01-01

6

Polyhexamethylene biguanide functionalized cationic silver nanoparticles for enhanced antimicrobial activity  

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

7

Production of Chemical Derivatives from Renewables  

SciTech Connect

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.

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

1996-06-01

8

Malabsorption of vitamin B12 and intrinsic factor secretion during biguanide therapy.  

PubMed

In a survey of 46 randomly selected diabetic patients on biguanide therapy, 30% had malabsorption of vitamin B12. Withdrawal of the drug resulted in normal absorption in only half of those with malabsorption. In most patients with persistent malabsorption, the results of absorption tests with exogenous intrinsic factor suggested the diagnosis of coincidental intrinsic factor deficiency. Further considerations, however, led to the concept that biguanides can induce malabsorption by two different mechanisms. One of these is temporary and unrelated to intrinsic factor secretion and the other is permanent and mediated by depression of intrinsic factor secretion. PMID:6825978

Adams, J F; Clark, J S; Ireland, J T; Kesson, C M; Watson, W S

1983-01-01

9

Successful use of locally applied polyhexamethylene biguanide as an adjunct to the treatment of fungal osteomyelitis  

PubMed Central

Fungal osteomyelitis is rare in immunocompetent patients and is often difficult to cure, even with optimal medical and surgical management. The authors present two cases of fungal osteomyelitis in which the common swimming pool cleaner, polyhexamethylene biguanide, was used successfully as an adjunct to standard surgical and medical treatment. Also presented is a literature review on the use of polyhexamethylene biguanide for this indication. The authors recommend that this safe and well-tolerated compound be considered as part of the treatment for fungal osteomyelitis. PMID:24421812

Walls, Genevieve; Noonan, Lisa; Wilson, Elizabeth; Holland, David; Briggs, Simon

2013-01-01

10

Chemicals from coal. Utilization of coal-derived phenolic compounds  

SciTech Connect

This article provides an overview for possible utilization of coal-derived phenolic compounds. Phenolic compounds are abundant in coal-derived liquids. Coal-derived phenolic compounds include phenol, cresol, catechol, methylcatechol, naphthol, and their derivatives. Liquids from coal liquefaction, pyrolysis, gasification, and carbonization are potential sources of phenolic chemicals, although certain processing and separation are needed. There are opportunities for coal-based phenolic chemicals, because there are existing industrial applications and potential new applications. Currently the petrochemical industry produces phenol in multi-step processes, and new research and development has resulted in a one-step process. Selective methylation of phenol can produce a precursor for aromatic engineering plastics. Catalytic oxidation of phenol has been commercialized recently for catechol production. There are potential new uses of phenol that could replace large-volume multi-step chemical processes that are based on benzene as the starting material. New chemical research on coal and coal-derived liquids can pave the way for their non-fuel uses for making chemicals and materials.

Song, C.; Schobert, H.H.

1999-07-01

11

Relevance of the OCT1 transporter to the antineoplastic effect of biguanides  

SciTech Connect

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.

Segal, Eric D.; Yasmeen, Amber; Beauchamp, Marie-Claude; Rosenblatt, Joshua [Division of Gynecologic Oncology, Jewish General Hospital, McGill University, Montreal, Quebec (Canada) [Division of Gynecologic Oncology, Jewish General Hospital, McGill University, Montreal, Quebec (Canada); Segal Cancer Center, Lady Davis Institute of Medical Research, McGill University, Montreal, Quebec (Canada); Pollak, Michael [Segal Cancer Center, Lady Davis Institute of Medical Research, McGill University, Montreal, Quebec (Canada) [Segal Cancer Center, Lady Davis Institute of Medical Research, McGill University, Montreal, Quebec (Canada); Department of Oncology, McGill University, Montreal, Quebec (Canada); Gotlieb, Walter H., E-mail: walter.gotlieb@mcgill.ca [Division of Gynecologic Oncology, Jewish General Hospital, McGill University, Montreal, Quebec (Canada); Segal Cancer Center, Lady Davis Institute of Medical Research, McGill University, Montreal, Quebec (Canada); Department of Oncology, McGill University, Montreal, Quebec (Canada)

2011-11-04

12

Evaluation of novel hydrophilic derivatives for chemically amplified EUV resists  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

13

CHEMICAL AND FUNCTIONAL CHARACTERIZATION OF CHICKPEA PROTEIN DERIVATES  

Microsoft Academic Search

Whole flour, defatted flour and freeze dried protein concentrate were obtained from chickpea. Protein solubility, water and oil absorption capacity, emulsifying capacity and emulsion stability, foaming capacity and foam stability were used to evaluate the chickpea protein derivates from a chemical and functional standpoint. The chickpea protein concentrate, obtained by alkaline solubilization (pH 10.5) followed by isoelectric precipitation at pH=

IONESCU AURELIA; APRODU IULIANA; BACIU CRISTINA; NICHITA ANDREI

14

Analytical Derivation of Moment Equations in Stochastic Chemical Kinetics  

PubMed Central

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

Sotiropoulos, Vassilios; Kaznessis, Yiannis N.

2011-01-01

15

Marine derived polysaccharides for biomedical applications: chemical modification approaches.  

PubMed

Polysaccharide-based biomaterials are an emerging class in several biomedical fields such as tissue regeneration, particularly for cartilage, drug delivery devices and gelentrapment systems for the immobilization of cells. Important properties of the polysaccharides include controllable biological activity, biodegradability, and their ability to form hydrogels. Most of the polysaccharides used derive from natural sources; particularly, alginate and chitin, two polysaccharides which have an extensive history of use in medicine, pharmacy and basic sciences, and can be easily extracted from marine plants (algae kelp) and crab shells, respectively. The recent rediscovery of poly-saccharidebased materials is also attributable to new synthetic routes for their chemical modification, with the aim of promoting new biological activities and/or to modify the final properties of the biomaterials for specific purposes. These synthetic strategies also involve the combination of polysaccharides with other polymers. A review of the more recent research in the field of chemical modification of alginate, chitin and its derivative chitosan is presented. Moreover, we report as case studies the results of our recent work concerning various different approaches and applications of polysaccharide-based biomaterials, such as the realization of novel composites based on calcium sulphate blended with alginate and with a chemically modified chitosan, the synthesis of novel alginate-poly(ethylene glycol) copolymers and the development of a family of materials based on alginate and acrylic polymers of potential interest as drug delivery systems. PMID:18830142

d'Ayala, Giovanna Gomez; Malinconico, Mario; Laurienzo, Paola

2008-01-01

16

Soybean Oil Derivatives for Fuel and Chemical Feedstocks  

SciTech Connect

Plant based sources of hydrocarbons are being considered as alternatives to petrochemicals because of the need to conserve petroleum resources for reasons of national security and climate change. Changes in fuel formulations to include ethanol from corn sugar and methyl esters from soybean oil are examples of this policy in the United States and elsewhere. Replacements for commodity chemicals are also being considered, as this value stream represents much of the profit for the oil industry and one that would be affected by shortages in oil or other fossil fuels. While the discovery of large amounts of natural gas associated with oil shale deposits has abated this concern, research into bio-based feedstock materials continues. In particular, this chapter reviews a literature on the conversion of bio-based extracts to hydrocarbons for fuels and for building block commodity chemicals, with a focus on soybean derived products. Conversion of methyl esters from soybean triglycerides for replacement of diesel fuel is an active area of research; however, the focus of this chapter will not reside with esterification or transesterification, except has a means to provide materials for the production of hydrocarbons for fuels or chemical feedstocks. Methyl ester content in vehicle fuel is limited by a number of factors, including the performance in cold weather, the effect of oxygen content on engine components particularly in the case of older engines, shelf-life, and higher NOx emissions from engines that are not tuned to handle the handle the enhanced pre-ignition conditions of methyl ester combustion [1]. These factors have led to interest in synthesizing a hydrocarbon fuel from methyl esters, one that will maintain the cetane number but will achieve better performance in an automobile: enhanced mixing, injection, and combustion, and reduce downstream issues such as emissions and upstream issues such as fuel preparation and transportation. Various catalytic pathways from oxygenated precursor to hydrocarbon will be considered in the review: pyrolysis [2], deoxygenation and hydrogenation [3, 4], and hydrotreatment [5]. The focus of many of these studies has been production of fuels that are miscible or fungible with petroleum products, e.g., the work published by the group of Daniel Resasco at U. Oklahoma [6]. Much of the published literature focuses on simpler chemical representatives of the methyl esters form soybean oil; but these results are directly applicable to the production of chemical feedstocks, such as ethylbenzene that can be used for a variety of products: polymers, solvent, and reagent [3]. Although many chemical pathways have been demonstrated in the laboratory, the scale-up to handle quantities of bio-derived material presents a number of challenges in comparison with petroleum refining. These range from additional transportation costs because of distributed feedstock production to catalyst cost and regeneration. Other chapters in the book appear to address the cultivation and harvesting of soybeans and production of oil, so these areas will not be dealt with directly in this chapter except as they may relate to chemical changes in the feedstock material. However, the feasibility of the production of hydrocarbons from soybean triglycerides or methyl esters derived from these triglycerides will be considered, along with remaining technical hurdles before soybeans can make a significant contribution to the hydrocarbon economy.

McFarlane, Joanna [ORNL

2013-01-01

17

Regulation of the Proliferation of Colon Cancer Cells by Compounds that Affect Glycolysis, Including 3-Bromopyruvate, 2-Deoxyglucose and Biguanides  

PubMed Central

In previous studies we observed that 2-deoxyglucose blocked the acidification of the medium used for culture of colon cancer cells caused by incubation with biguanides and had an additive inhibitory effect on growth. In the present work, we found that 3-bromopyruvate can also prevent the lowering of pH caused by biguanide treatment. 3-Bromopyruvate inhibited colonic cancer cell proliferation but the effect was not always additive to that of biguanides and an additive effect was more notable in combined treatment with 3-bromopyruvate and 2-deoxyglucose. The induction of alkaline phosphatase activity by butyrate was not consistently affected by combination with other agents that modified glucose metabolism. The drug combinations that were examined inhibited proliferation of wild-type and P53 null cells and affected colonic cancer lines with different growth rates. PMID:23393330

Lea, Michael A.; Qureshi, Mehreen S.; Buxhoeveden, Michael; Gengel, Nicolette; Kleinschmit, Jessica; desBordes, Charles

2013-01-01

18

Regulation of the proliferation of colon cancer cells by compounds that affect glycolysis, including 3-bromopyruvate, 2-deoxyglucose and biguanides.  

PubMed

In previous studies performed by our group, we observed that 2-deoxyglucose blocked the acidification of the medium used for culture of colon cancer cells caused by incubation with biguanides and it had an additive inhibitory effect on growth. In the present work, we found that 3-bromopyruvate can also prevent the lowering of pH caused by biguanide treatment. 3-Bromopyruvate inhibited colonic cancer cell proliferation, but the effect was not always additive to that of biguanides and an additive effect was more notable in combined treatment with 3-bromopyruvate and 2-deoxyglucose. The induction of alkaline phosphatase activity by butyrate was not consistently affected by combination with other agents that modified glucose metabolism. The drug combinations that were examined inhibited proliferation of wild-type and p53-null cells and affected colonic cancer lines with different growth rates. PMID:23393330

Lea, Michael A; Qureshi, Mehreen S; Buxhoeveden, Michael; Gengel, Nicolette; Kleinschmit, Jessica; Desbordes, Charles

2013-02-01

19

Blockade of the antinociception induced by diclofenac, but not of indomethacin, by sulfonylureas and biguanides.  

PubMed

There is evidence that administration of sulfonylureas, such as glibenclamide and tolbutamide, blocks diclofenac-induced antinociception, suggesting that diclofenac activates ATP-sensitive K(+) channels. However, there is no evidence for the interaction between diclofenac and other hypoglycemic drugs, such as the biguanides metformin or phenformin. Therefore, this work was undertaken to determine whether two sulfonylureas, glibenclamide and glipizide, as well as two biguanides, metformin and phenformin, have any effect on the systemic antinociception that is induced by diclofenac and indomethacin using the rat formalin test as an animal model. Systemic injections of diclofenac (10 to 30mg/kg) and indomethacin (10 to 30mg/kg) produced dose-dependent antinociception during the second phase of the test. Systemic pretreatment with glibenclamide (3 and 10mg/kg), glipizide (3 and 10mg/kg), metformin (100 and 180mg/kg) or phenformin (100 and 180mg/kg) blocked diclofenac-induced systemic antinociception in the second phase of the test (P<0.05). In contrast, pretreatment with glibenclamide, glipizide, metformin or phenformin did not block indomethacin-induced systemic antinociception (P>0.05). These data suggest that diclofenac, but not indomethacin, activated K(+) channels and metformin and phenformin-dependent mechanisms, which resulted in systemic antinociceptive effects in the rat formalin test. PMID:21397627

Ortiz, Mario I

2011-07-01

20

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

PubMed

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. PMID:24670634

Birsoy, K?vanç; 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

21

Metabolic determinants of cancer cell sensitivity to glucose limitation and biguanides  

PubMed Central

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

Birsoy, K?vanc; 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

22

Biologically significant physico-chemical properties of antioxidative prostaglandin derivatives.  

PubMed

A monomeric derivative and several oligomeric derivatives were synthesized from prostaglandin B2. Their lipid solubility was studied by measuring their octanol-water partition coefficients. With EPR spectroscopy, the oligomeric derivatives were shown to have g = 2 signal, indicating these compounds have intrinsic free radicals. Measuring the rate of adenochrome formation, it was shown that these derivatives could scavenge superoxide anions. Using a spin-trapping technique employing DMPO, we found that these oligomers could also scavenge hydroxyl radicals. The calcium chelating activity of these compounds were also studied. In an in vitro rat model, these compounds inhibited lipid peroxidation as measured by the production of thiobarbituric acid reacting substances. Other prostaglandin oligomeric derivatives synthesized from PGE1 were also studied, and their properties were compared with these new compounds. Results suggest that both the water solubility and the chelating activity for calcium ions may not be related to their protective effects in ischemic or traumatic injury. PMID:1667725

Ohnishi, S T; Ohnishi, T

1991-12-01

23

Microbial production of fatty acid-derived fuels and chemicals  

PubMed Central

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

Lennen, Rebecca M; Pfleger, Brian F

2013-01-01

24

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

PubMed

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. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:3914-3923, 2014. PMID:25336429

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

2014-12-01

25

Toxicological Actions of Plant-Derived and Anthropogenic Methylenedioxyphenyl-Substituted Chemicals in Mammals and Insects  

Microsoft Academic Search

The methylenedioxyphenyl (MDP) substituent is a structural feature present in many plant chemicals that deter foraging by predatory insects and herbivores. With increasing use of herbal extracts in alternative medicine, human exposure to MDP-derived plant chemicals may also be significant. Early studies found that most MDP agents themselves possess relatively low intrinsic toxicity, but strongly influence the actions of other

Michael Murray

2012-01-01

26

Photophysical properties of multiply phenylated C70 derivatives: Spectroscopic and quantum-chemical investigations  

Microsoft Academic Search

The photophysics of six multiply phenylated C70 derivatives [C70Ph2, C70Ph4, C70Ph6 (two regioisomers), C70Ph8 and C70Ph10] have been investigated by means of steady state spectroscopy in cyclohexane solution and quantum-chemical calculations derived from semiempirical Hartree-Fock approaches. There is good agreement between the measured absorption spectra and the INDO\\/SCI calculated excitation energies for each derivative. The foregoing results and some additional

P.-F. Coheur; J. Cornil; D. A. Dos Santos; P. R. Birkett; J. Liévin; J. L. Brédas; D. R. M. Walton; R. Taylor; H. W. Kroto; R. Colin

2000-01-01

27

[Synthesis, chemical and toxicological study of a new benzimidazol derivative].  

PubMed

Hydatidosis is a cosmopolitan parasitic disease that remains a real public health problem in highly endemic countries. Surgery is the mainstay treatment, but with significant morbidity and mortality. In addition, contraindications for surgery emphasize the importance of developing effective medications. Currently, albendazole is the main anti-hydatid agent used worldwide. It has proven efficacy but limited bioavailability due to weak absorption. In order to improve the bioavailability of this molecule we synthesized an ester of albendazole, which exhibits a totally modified solubility compared with the princeps compound. This synthesis was achieved with an output of 75%. The structure of the synthetic product was established by IR spectrometry and by proton nuclear magnetic resonance. A careful toxicity study revealed that this product has little toxicity when administered intraperitoneally and orally in mice, with a lethal dose 50 of 2,500 mg/kg per os and 2,250 mg/kg intraperitoneally, values comparable to those of albendazole. This in vitro parasitological study demonstrated that the chemical changes introduced on the albendazole molecule had no effect on its antiparasitic activity. PMID:19298890

Ansar, M; Zellou, A; Faouzi, M E A; Zahidi, A; Serroukh, S; Lmimouni, B E; Cherrah, Y; Taoufik, J

2009-03-01

28

Conical intersection seams in polyenes derived from their chemical composition  

SciTech Connect

The knowledge of conical intersection seams is important to predict and explain the outcome of ultrafast reactions in photochemistry and photobiology. They define the energetic low-lying reachable regions that allow for the ultrafast non-radiative transitions. In complex molecules it is not straightforward to locate them. We present a systematic approach to predict conical intersection seams in multifunctionalized polyenes and their sensitivity to substituent effects. Included are seams that facilitate the photoreaction of interest as well as seams that open competing loss channels. The method is based on the extended two-electron two-orbital method [A. Nenov and R. de Vivie-Riedle, J. Chem. Phys. 135, 034304 (2011)]. It allows to extract the low-lying regions for non-radiative transitions, which are then divided into small linear segments. Rules of thumb are introduced to find the support points for these segments, which are then used in a linear interpolation scheme for a first estimation of the intersection seams. Quantum chemical optimization of the linear interpolated structures yields the final energetic position. We demonstrate our method for the example of the electrocyclic isomerization of trifluoromethyl-pyrrolylfulgide.

Nenov, Artur; Vivie-Riedle, Regina de [Department Chemie, Ludwig-Maximilians-Univerisitaet, Muenchen Butenandtstr. 11, 81377 Muenchen (Germany)

2012-08-21

29

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

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

30

Inorganic salts of biguanide Searching for new materials for second harmonic generation  

NASA Astrophysics Data System (ADS)

Five inorganic salts of biguanide with carbonic, nitric, phosphoric and phosphorous acids were prepared and X-ray structural analysis has been performed for three novel compounds. Biguanidium(1+) phosphite trihydrate crystallizes in the triclinic space group P1¯, a = 7.1470(1) Å, b = 9.6530(2) Å, c = 11.3140(2) Å, ? = 70.094(1)°, ? = 75.688(1)°, ? = 86.099(1)°, V = 713.71(2) Å 3, Z = 2, R = 0.0350 for 3031 observed reflections. The crystal structure is based on a network of phosphite anions and water molecules. Biguanidium(1+) cations form pairs through two intermolecular hydrogen bonds of the N-H…N type and fill the network with anions and water molecules. Biguanidium(2+) phosphite monohydrate crystallizes in the triclinic space group P1¯, a = 6.9690(2) Å, b = 7.3500(3) Å, c = 8.1730(3) Å, ? = 82.518(2)°, ? = 83.015(2)°, ? = 82.811(2)°, V = 409.44(3) Å 3, Z = 2, R = 0.0308 for 1779 observed reflections. The structure is formed of a network of alternating biguanidium(2+) cations, phosphite anions and pairs of water molecules interconnected by a system of intermolecular hydrogen bonds. Biguanidium(2+) hydrogen phosphate monohydrate crystallizes in the triclinic space group P1¯, a = 7.0630(2) Å, b = 7.8740(3) Å, c = 8.1120(3) Å, ? = 102.706(2)°, ? = 104.976(2)°, ? = 92.632(3)°, V = 422.61(3) Å 3, Z = 2, R = 0.0337 for 1827 observed reflections. The crystal structure is formed by pairs of anions that are mutually connected in chains through two water molecules. These chains are interconnected by biguanidium(2+) cations to form a three-dimensional network. The FTIR and FT Raman spectra of all five compounds were recorded, calculated (HF, B3LYP and MP2 methods) and discussed. Quantitative measurements of second harmonic generation of powdered biguanidium(2+) nitrate and novel biguanidium(2+) carbonate monohydrate at 800 nm were performed and a relative efficiency (compared to KDP) of 87% and 20% was observed, respectively.

Matulková, Irena; N?mec, Ivan; Císa?ová, Ivana; N?mec, Petr; Mi?ka, Zden?k

2008-08-01

31

Development of novel protecting derivatives for chemically amplified extreme ultraviolet resist  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

32

Effects of disorder on the transport properties of chemically derived graphene  

Microsoft Academic Search

Transport properties of chemically derived graphene (CDG) are strongly influenced by the concentration of defects that are introduced during synthesis. We present a comprehensive transport study on a range of CDG films with varying degrees of disorder. The electric properties of CDG were found to be tunable over several orders of magnitude via controlled oxidation and reduction. The structural properties

Goki Eda; James Ball; Ye Xiao; Robert Maher; Lesley Cohen; Thomas Anthopoulos; Manish Chhowalla

2011-01-01

33

Chemical Vapor Deposition-Derived Graphene with Electrical Performance of Exfoliated Graphene  

E-print Network

a scalable method to produce large-area graphene, CVD-grown graphene has heretofore exhibited inferior deposition (CVD) offers a promising method to produce large-area films of graphene, crucialChemical Vapor Deposition-Derived Graphene with Electrical Performance of Exfoliated Graphene

Hone, James

34

Higher derivative effects on {eta}/s at finite chemical potential  

SciTech Connect

We examine the effects of higher derivative corrections on {eta}/s, the ratio of shear viscosity to entropy density, in the case of a finite R-charge chemical potential. In particular, we work in the framework of five-dimensional N=2 gauged supergravity, and include terms up to four derivatives, representing the supersymmetric completion of the Chern-Simons term A and Tr(R and R). The addition of the four-derivative terms yields a correction which is a 1/N effect, and in general gives rise to a violation of the {eta}/s bound. Furthermore, we find that, once the bound is violated, turning on the chemical potential only leads to an even larger violation of the bound.

Cremonini, Sera; Hanaki, Kentaro; Liu, James T.; Szepietowski, Phillip [Michigan Center for Theoretical Physics, Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

2009-07-15

35

Photophysical properties of multiply phenylated C70 derivatives: Spectroscopic and quantum-chemical investigations  

NASA Astrophysics Data System (ADS)

The photophysics of six multiply phenylated C70 derivatives [C70Ph2, C70Ph4, C70Ph6 (two regioisomers), C70Ph8 and C70Ph10] have been investigated by means of steady state spectroscopy in cyclohexane solution and quantum-chemical calculations derived from semiempirical Hartree-Fock approaches. There is good agreement between the measured absorption spectra and the INDO/SCI calculated excitation energies for each derivative. The foregoing results and some additional ground state properties calculated at the AM1 level have been used to predict that the perturbation of the ? electronic system of the cage results in significant changes in the photophysics of the fullerene derivatives. The effects of conjugation and spatial localization of the HOMO and LUMO orbitals on the energy of the first electronic transition are discussed in greater detail.

Coheur, P.-F.; Cornil, J.; Dos Santos, D. A.; Birkett, P. R.; Liévin, J.; Brédas, J. L.; Walton, D. R. M.; Taylor, R.; Kroto, H. W.; Colin, R.

2000-04-01

36

Structures, electrochemical and spectroscopic properties of ternary ruthenium(II)-polypyridyl complexes with additional carboxylate, biguanide or sulfonamide donors  

Microsoft Academic Search

The following complexes have been prepared: [Ru(bipy)2(pic)][PF6] (bipy=2,2?-bipyridine; Hpic= picolinic acid); [Ru(terpy)(dipic)] (terpy=2,2?:6?,2?-terpyridine; H2dipic=dipicolinic acid); [Ru(bipy)2 (Hbig)][PF6]2 (Hbig=biguanide); and [Ru(bipy)2(apps)][PF6] [where Happs is the p-tolylsulfonamide of 2-(2-aminophenyl)-pyridine]. The latter three have been characterised by X-ray crystallography and are all mononuclear pseudo-octachedral complexes. Electrochemical studies reveal the relationship between the potential of the metal-based Ru(II)\\\\Ru(III) couple, with the potential values being

Samantha M Couchman; José M Dominguez-Vera; John C Jeffery; Colin A McKee; Simon Nevitt; Matthias Pohlman; Claire M White; Michael D Ward

1998-01-01

37

Quantum-mechanics-derived 13Calpha chemical shift server (CheShift) for protein structure validation.  

PubMed

A server (CheShift) has been developed to predict (13)C(alpha) chemical shifts of protein structures. It is based on the generation of 696,916 conformations as a function of the phi, psi, omega, chi1 and chi2 torsional angles for all 20 naturally occurring amino acids. Their (13)C(alpha) chemical shifts were computed at the DFT level of theory with a small basis set and extrapolated, with an empirically-determined linear regression formula, to reproduce the values obtained with a larger basis set. Analysis of the accuracy and sensitivity of the CheShift predictions, in terms of both the correlation coefficient R and the conformational-averaged rmsd between the observed and predicted (13)C(alpha) chemical shifts, was carried out for 3 sets of conformations: (i) 36 x-ray-derived protein structures solved at 2.3 A or better resolution, for which sets of (13)C(alpha) chemical shifts were available; (ii) 15 pairs of x-ray and NMR-derived sets of protein conformations; and (iii) a set of decoys for 3 proteins showing an rmsd with respect to the x-ray structure from which they were derived of up to 3 A. Comparative analysis carried out with 4 popular servers, namely SHIFTS, SHIFTX, SPARTA, and PROSHIFT, for these 3 sets of conformations demonstrated that CheShift is the most sensitive server with which to detect subtle differences between protein models and, hence, to validate protein structures determined by either x-ray or NMR methods, if the observed (13)C(alpha) chemical shifts are available. CheShift is available as a web server. PMID:19805131

Vila, Jorge A; Arnautova, Yelena A; Martin, Osvaldo A; Scheraga, Harold A

2009-10-01

38

Xenobiotic responsiveness of Arabidopsis thaliana to a chemical series derived from a herbicide safener.  

PubMed

Plants respond to synthetic chemicals by eliciting a xenobiotic response (XR) that enhances the expression of detoxifying enzymes such as glutathione transferases (GSTs). In agrochemistry, the ability of safeners to induce an XR is used to increase herbicide detoxification in cereal crops. Based on the responsiveness of the model plant Arabidopsis thaliana to the rice safener fenclorim (4,6-dichloro-2-phenylpyrimidine), a series of related derivatives was prepared and tested for the ability to induce GSTs in cell suspension cultures. The XR in Arabidopsis could be divided into rapid and slow types depending on subtle variations in the reactivity (electrophilicity) and chemical structure of the derivatives. In a comparative microarray study, Arabidopsis cultures were treated with closely related compounds that elicited rapid (fenclorim) and slow (4-chloro-6-methyl-2-phenylpyrimidine) XRs. Both chemicals induced major changes in gene expression, including a coordinated suppression in cell wall biosynthesis and an up-regulation in detoxification pathways, whereas only fenclorim selectively induced sulfur and phenolic metabolism. These transcriptome studies suggested several linkages between the XR and oxidative and oxylipin signaling. Confirming links with abiotic stress signaling, suppression of glutathione content enhanced GST induction by fenclorim, whereas fatty acid desaturase mutants, which were unable to synthesize oxylipins, showed an attenuated XR. Examining the significance of these studies to agrochemistry, only those fenclorim derivatives that elicited a rapid XR proved effective in increasing herbicide tolerance (safening) in rice. PMID:21778235

Skipsey, Mark; Knight, Kathryn M; Brazier-Hicks, Melissa; Dixon, David P; Steel, Patrick G; Edwards, Robert

2011-09-16

39

Surface chemical functionalities affect the behavior of human adipose-derived stem cells in vitro  

NASA Astrophysics Data System (ADS)

This study examines the effect of surface chemical functionalities on the behavior of human adipose-derived stem cells (hASCs) in vitro. Plasma polymerized films rich in amine (sbnd NH2), carboxyl (sbnd COOH) and methyl (sbnd CH3), were generated on hydroxyapatite (HAp) substrates. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy (XPS). The ability of different substrates to absorb proteins was evaluated. The results showed that substrates modified with hydrophilic functional group (sbnd COOH and sbnd NH2) can absorb more proteins than these modified with more hydrophobic functional group (sbnd CH3). The behavior of human adipose-derived stem cells (hASCs) cultured on different substrates was investigated in vitro: cell counting kit-8 (CCK-8) analysis was used to characterize cell proliferation, scanning electronic microscopy (SEM) analysis was used to characterize cell morphology and alkaline phosphatase (ALP) activity analysis was used to account for differentiation. The results of this study demonstrated that the sbnd NH2 modified surfaces encourage osteogenic differentiation; the sbnd COOH modified surfaces promote cell adhesion and spreading and the sbnd CH3 modified surfaces have the lowest ability to induce osteogenic differentiation. These findings confirmed that the surface chemical states of biomaterials can affect the behavior of hASCs in vitro.

Liu, Xujie; Feng, Qingling; Bachhuka, Akash; Vasilev, Krasimir

2013-04-01

40

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

SciTech Connect

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.

Watson, A.P.

2003-07-24

41

A pathwise derivative approach to the computation of parameter sensitivities in discrete stochastic chemical systems.  

PubMed

Characterizing the sensitivity to infinitesimally small perturbations in parameters is a powerful tool for the analysis, modeling, and design of chemical reaction networks. Sensitivity analysis of networks modeled using stochastic chemical kinetics, in which a probabilistic description is used to characterize the inherent randomness of the system, is commonly performed using Monte Carlo methods. Monte Carlo methods require large numbers of stochastic simulations in order to generate accurate statistics, which is usually computationally demanding or in some cases altogether impractical due to the overwhelming computational cost. In this work, we address this problem by presenting the regularized pathwise derivative method for efficient sensitivity analysis. By considering a regularized sensitivity problem and using the random time change description for Markov processes, we are able to construct a sensitivity estimator based on pathwise differentiation (also known as infinitesimal perturbation analysis) that is valid for many problems in stochastic chemical kinetics. The theoretical justification for the method is discussed, and a numerical algorithm is provided to permit straightforward implementation of the method. We show using numerical examples that the new regularized pathwise derivative method (1) is able to accurately estimate the sensitivities for many realistic problems and path functionals, and (2) in many cases outperforms alternative sensitivity methods, including the Girsanov likelihood ratio estimator and common reaction path finite difference method. In fact, we observe that the variance reduction using the regularized pathwise derivative method can be as large as ten orders of magnitude in certain cases, permitting much more efficient sensitivity analysis than is possible using other methods. PMID:22280752

Sheppard, Patrick W; Rathinam, Muruhan; Khammash, Mustafa

2012-01-21

42

Chemical control of photochromism and a multiresponsive molecular switch based on a diarylethene derivative containing naphthol.  

PubMed

A photochemically inactive diarylethene derivative with a naphthol group bridging through the imidazole unit (DIN) was synthesized to characterize a multifunctional switch. Upon stimulation by radiation (UV and visible light), the target diarylethene derivative DIN was not photochemically inactive but photo-active, it could be photo-converted into a keto compound. Moreover, the photochromic reaction of DIN was observed when it was stimulated by the addition of acid or methylation. Fluorescence quenching and the bathochromic effect occurred when DIN was stimulated by the addition of copper ions and a base, respectively. Its optical properties could be regulated by various chemical stimuli. Thus, it can potentially be utilized as a multiresponsive molecular switch. PMID:25341073

Liu, Wenju; Li, Ziyong; Hu, Fang; Yin, Jun; Yu, Guang-Ao; Liu, Sheng Hua

2014-12-12

43

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

PubMed

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

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

2013-07-01

44

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

SciTech Connect

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.

Kundhikanjana, W.

2010-06-02

45

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

PubMed

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

Martín, M A; González, I; Siles, J A; Berrios, M; Martín, A

2013-04-01

46

[Spectral analysis of dissolved organic matter derived from rice straw after chemical treatment].  

PubMed

Fourier transform infrared spectroscopy (FTIR), ultraviolet spectroscopy (UV), and nuclear magnetic resonance spectroscopy (NMR) were used to study the chemical composition of Dissolved Organic Matter (DOM) derived from rice straw in the hydrolysis process with a dilute complex acid solution. The results obtained are as follows. FTIR spectra could indicate the changes of DOM during the hydrolysis process of rice straw. With the progress of rice straw hydrolysis, methyl, methylene, aromatic compounds and carbohydrates decreased, most of aliphatic compounds were oxidized to CO2 and H2O, and others were turned into carbonates. Most of the organic silicon was hydrolyzed into inorganic silicon. The proteins, amino acids and other nitrogen were hydrolyzed to NH4+. All the recalcitrant fractions of rice straw, such as hemi-cellulose, cellulose and silicon sharply decreased during the process of chemical treatment. The results obtained in this paper proposed that the changes of DOM of rice straw in the hydrolysis could be an indication in the changes of chemical composition of rice straw during the hydrolyzation, and FTIR, UV and NMR were good methods to study the changes in the structure of organic compounds. PMID:15856553

Shen, Qi-Rong; Xu, Yong; Yang, Hong; Zhou, Li-Xiang; Yu, Qing; Zhou, Zhi-Ping

2005-02-01

47

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

PubMed

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

Runguphan, Weerawat; Keasling, Jay D

2014-01-01

48

Effect of chemical structure on the release of certain propionic acid derivatives from their dosage forms.  

PubMed

The aim of this study was to investigate the relationship between the chemical structure and release properties of certain drug products. Propionic acid derivatives were used as a model. These include ibuprofen (I), ketoprofen (K), tiaprofenic acid (T), flurbiprofen (F), and naproxen (N). They are all aryl derivatives of propionic acid and differ only in the aryl group. Such an aryl group may be either isobutylphenyl, benzoylphenyl, benzoylthienyl, fluorobiphenyl, or methoxynaphthyl group in I, K, T, F, and N, respectively. Three dosage forms were selected for this study: capsules, suppositories, and creams. The release of propionic acid derivatives from the capsules and suppositories decreased in the order ibuprofen > tiaprofenic acid > ketoprofen > flurbiprofen > naproxen, and for the creams the release decreased in the order ibuprofen > tiaprofenic acid > flurbiprofen > ketoprofen > naproxen. The difference in drug release in the first case was attributed to the difference in the chain length, and in the creams which are composed of two phases, the partition coefficient was found to affect the drug release. The molecular weight of the drug had no effect on the release. The drug release from different dosage forms was not affected after 1 month storage. PMID:9876606

el-Bary, A A; el-Nabarawi, M A; Mohamed, M I

1998-05-01

49

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

SciTech Connect

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.

David C. Dayton

2010-03-24

50

An overview on chemical aspects and potential health benefits of limonoids and their derivatives.  

PubMed

Limonoids are heavily oxygenated, modified triterpenes dominant in Meliaceae and Rutaceae plant families. The term 'limonoid' is derived from limonin, which was first identified as the bitter constituent of Citrus seeds in 1841. This group of secondary metabolites exhibits a wide range of biological properties, including anticancer, antibacterial, antifungal, antimalarial, and antiviral activities. Significant progress on the role of limonoids as promising candidates for cancer chemoprevention and/or therapy has been achieved in particular in recent years. The aim of this review article is to discuss the recent developments on limonoids chemical aspects and biological activities with the relationship between structure and activity, supporting the new possibilities for the medicinal and/or nutraceutical use of these compounds. PMID:24188270

Tundis, Rosa; Loizzo, Monica Rosa; Menichini, Francesco

2014-01-01

51

Engineering catalyst microenvironments for metal-catalyzed hydrogenation of biologically derived platform chemicals.  

PubMed

It is shown that microenvironments formed around catalytically active sites mitigate catalyst deactivation by biogenic impurities that are present during the production of biorenewable chemicals from biologically derived species. Palladium and ruthenium catalysts are inhibited by the presence of sulfur-containing amino acids; however, these supported metal catalysts are stabilized by overcoating with poly(vinyl alcohol) (PVA), which creates a microenvironment unfavorable for biogenic impurities. Moreover, deactivation of Pd catalysts by carbon deposition from the decomposition of highly reactive species is suppressed by the formation of bimetallic PdAu nanoparticles. Thus, a PVA-overcoated PdAu catalyst was an order of magnitude more stable than a simple Pd catalyst in the hydrogenation of triacetic acid lactone, which is the first step in the production of biobased sorbic acid. A PVA-overcoated Ru catalyst showed a similar improvement in stability during lactic acid hydrogenation to propylene glycol in the presence of methionine. PMID:25196504

Schwartz, Thomas J; Johnson, Robert L; Cardenas, Javier; Okerlund, Adam; Da Silva, Nancy A; Schmidt-Rohr, Klaus; Dumesic, James A

2014-11-17

52

Formation and characterization of wrinkle structures of chemically-derived graphene thin films and micropatterns.  

PubMed

In this study, we report a simple and effective process for the fabrication of wrinkle structures of chemically derived graphene thin films and patterns. Reduced graphene oxide (rGO) thin films/patterns formed on glass substrates are transferred to pre-strained elastomeric layers by improving adhesion strength at the rGO/PDMS interface with the assistance of oxygen plasma treatment. The morphology of rGO wrinkle structures is investigated in the various applied strains and film thicknesses. The experimental results were interpreted by theoretical models and well fitted to the estimated values. The techniques for such well-defined rGO wrinkle structures could be used for flexible and stretchable graphene-based electronic devices. PMID:24734632

Kim, Nam Hee; Ko, Yeongun; Cho, Sung-Rheb; Chang, Suk Tai

2014-05-01

53

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

PubMed

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

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

2014-01-01

54

Fatty Acid-Derived Biofuels and Chemicals Production in Saccharomyces cerevisiae  

PubMed Central

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.

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

2014-01-01

55

Development and application of sol-gel-derived platforms for chemical and biological sensing  

NASA Astrophysics Data System (ADS)

The sol-gel process allows the production of controlled pore glasses under ambient temperature and pressure conditions. The low temperature processing conditions allows the incorporation of organic and even biological species within these glass composites. Thus, the tunable physical characteristics of the final sol-gel composite (e.g., porosity, refractive index) coupled with the ability to "immobilize" chemical and biological recognition elements within these matrices, make them attractive as chemical sensing platforms. The successful inclusion of a recognition element within these matrices requires a detailed understanding of how the sol-gel-processed materials affects the dopant species. Toward this end, we have investigated the behavior of a series of model dopants (organic fluorophores and proteins) entrapped within sol-gel-derived composites as a means to determine the sol-gel-processed composite affects the dopant. We also present new methods for producing stable, sol-gel-based thin films. Finally, we used these thin-film formats to produce a prototypical immunosensor, and tunable pressure-sensitive coatings.

Jordan, Jeffrey David

56

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

PubMed

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

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

2014-03-01

57

Iodinated derivatives of vasoactive intestinal peptide (VIP), PHI and PHM: purification, chemical characterization and biological activity  

SciTech Connect

The iodination of vasoactive intestinal peptide (VIP) was studied, using a variety of enzymatic and chemical iodination methods. Reversed phase high performance liquid chromatography (HPLC) was used to purify the reaction products. The lactoperoxidase-glucose oxidase method gave excellent results in terms of reproducibility, iodine incorporation, and yield of the non-oxidized products (Tyr(I)10)VIP and (Tyr(I)22)VIP, and was used to prepare both /sup 125/I and /sup 127/I labelled derivatives. In both cases, direct application to HPLC and a single column system were used. Although the oxidized peptides (Tyr(I)10,Met(O)17)VIP and (Tyr(I)22,Met(O)17)VIP could be generated to varying degrees directly by iodination of VIP, these were most conveniently prepared by iodination of (Met(O)17)VIP. Iodinated derivatives of the homologous peptides PHI and PHM were likewise prepared by rapid, one-step HPLC procedures. The site and degree of iodination were determined by HPLC peptide mapping of tryptic digests and amino acid analyses, and in the case of (Tyr(I)10)VIP also by sequencing. The vasorelaxant activities of the iodinated peptides in bovine cerebral artery preparations did not differ significantly from those of the corresponding noniodinated peptides, with the exception of (Tyr(I)10,Met(O)17)VIP and (Tyr(I)22,Met(O)17)VIP which, unlike (Met(O)17)VIP itself, had slightly lower potency than VIP.

McMaster, D.; Suzuki, Y.; Rorstad, O.; Lederis, K.

1987-07-01

58

Derivate  

NSDL National Science Digital Library

In this activity, students input functions in order to calculate the derivative and tangent line of that function. This activity allows students to explore tangent lines of various functions. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2010-01-01

59

On accuracy of the 13C NMR chemical shift GIAO calculations of fullerene C 60 derivatives at PBE\\/3? approach  

Microsoft Academic Search

The correlation analysis of the calculated by means of GIAO PBE\\/3? method and experimental (2D NMR INADEQUATE) 13C NMR chemical shifts of C60 derivatives was performed. It was shown that the computational method with sufficient accuracy (r.m.s.?5ppm) reproduces the experimental 13C NMR chemical shifts of the sp2-fullerene carbon atoms uncoupled with the sp3-fullerene carbons. By quality description the GIAO method

Arthur R. Tulyabaev; Leonard M. Khalilov

2011-01-01

60

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

PubMed

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

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

2013-06-14

61

Chemical Solution Derived Planarization Layers for Highly Aligned IBAD MgO Templates  

SciTech Connect

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.

Paranthaman, Mariappan Parans [ORNL] [ORNL; Aytug, Tolga [ORNL] [ORNL; Stan, Liliana [Los Alamos National Laboratory (LANL)] [Los Alamos National Laboratory (LANL); Jia, Quanxi [Los Alamos National Laboratory (LANL)] [Los Alamos National Laboratory (LANL); Cantoni, Claudia [ORNL] [ORNL; Wee, Sung Hun [ORNL] [ORNL

2014-01-01

62

Amphiphilic lauryl ester derivatives from aromatic amino acids: significance of chemical architecture in aqueous aggregation properties.  

PubMed

Lauryl esters of L-tyrosine (LET) and L-phenylalanine (LEP) were, in a previous interface adsorption study, found to adopt very different interfacial conformations. The present study is an investigation of their aqueous aggregation properties with the goal of elucidating the effects of the presence in LET and absence in LEP of the phenolic OH group on their aqueous aggregate structures and micellar conformations of the surfactant monomers. The measured properties included aggregation numbers from time-resolved fluorescence quenching (TRFQ), interface hydration index and microviscosity by electron spin resonance (ESR), chemical shifts of (1)H resonance lines by NMR, and Krafft temperatures and enthalpies of structural transitions by differential scanning calorimetry (DSC). The TRFQ, ESR, and NMR experiments were conducted at various temperatures from 23 to 70 degrees C for various surfactant concentrations from 0.050 to 0.200 M. Markedly different temperature dependences of aggregation number and (1)H NMR chemical shifts are exhibited by LET and LEP micelles. LET and LEP form ionic micelles. The aggregation number of LEP decreases as is characteristic of ionic micelles, but that of LET increases slightly with temperature. The changes with temperature in the NMR chemical shifts and width of the resonance lines are significantly greater for the various LEP protons than for those of LET. The differences in these properties and other fluorescence decay characteristics of fluorophores incorporated into the micelles could be attributed to the difference in the micellar conformations of LET and LEP which are postulated to be similar to that at oil-water interfaces. The phenolic group is hypothesized to be in the micelle-water interface as part of the headgroup in LET micelles, and its location does not change with temperature. On the other hand, in LEP micelles, the phenyl ring is folded into the core overlapping with the flexible hydrophobic chains. The resulting closer proximity between the phenyl ring and the flexible hydrocarbon chain causes interdependence of the phenyl ring and chain proton resonances, leading to the observed temperature dependence of the chemical shifts in LEP. The TRFQ and ESR data are combined together in a molecular space-filling model, referred to as the polar shell model, to derive the geometrical properties of the micelle. The DSC scans in the temperature range 10-55 degrees C showed the presence of distinctly different endotherms for LET and LEP. The Krafft temperatures, K(T), and the enthalpies were determined. The higher K(T) and broader peak of the DSC endotherm of LET as compared to LEP are attributed to the stabilization of fiberlike structures below the Krafft temperature due to its chirality and the hydrogen bonding capability of the phenolic OH and also to the ion-dipole interactions. Thus, all of the observed differences between LET and LEP could be attributed to the difference in their chemical architecture. PMID:19778004

Vijay, R; Singh, Jasmeet; Baskar, Geetha; Ranganathan, Radha

2009-10-22

63

Chemical compositional, biological, and safety studies of a novel maple syrup derived extract for nutraceutical applications.  

PubMed

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

Zhang, Yan; Yuan, Tao; Li, Liya; Nahar, Pragati; Slitt, Angela; Seeram, Navindra P

2014-07-16

64

Determination of chemical components derived from 2% chlorhexidine gel degradation using gas chromatography-mass spectrometry.  

PubMed

Abstract Objective. This study determined the chemical components derived from degradation of 2% chlorhexidine (CHX) gel and solution by using gas chromatography-mass spectrometry. Materials and methods. Three 2% CHX gels were used to identify the products of CHX gel degradation using gas chromatography-mass spectrometry. A solution of CHX was also evaluated to compare the degradation between gel and solution. Degradation was evaluated in four storage situations (on the worktable with light: on the worktable without light; in the Pasteur oven at 36.5°C without light; and in the refrigerator at 8°C without light). Measurements were made at four time points: initial analysis and 1, 3 and 6 months after. The conversion of CHX into para-chloroaniline in storage situations and in different periods was analyzed statistically using chi-square test (? = 5%). Results. The 2% CHX gel or solution had already degraded vial found within the period of validity, at all time points and for all storage conditions. The amount of para-chloroaniline (pCA) was directly proportional to time in the case of CHX solution, but not in CHX gel due to lack of homogeneity. CHX homogeneity in hydroxyethylcellulose gel was directly dependent on compounding mode. Conclusions. Degradation products, such as para-chloroaniline (pCA), orto- chloroaniline (oCA), meta-chloroaniline (mCA), reactive oxygen species (ROS) and organochlorines (ortho-chlorophenyl isocyanate and 2-amino-5-clorobenzonitrila) were found in 2% CHX gel and solution, regardless of storage conditions or time. In relationship to gel homogenization an alternative to produce 2% CHX gel and a new homogenization method have been developed. PMID:24850506

Câmara De Bem, Samuel Henrique; Estrela, Carlos; Guedes, Débora Fernandes Costa; Sousa-Neto, Manoel Damião; Pécora, Jesus Djalma

2014-11-01

65

Quantum-chemical study of the CH acidities of methyl derivatives of five-membered aromatic heterocycles  

Microsoft Academic Search

The CNDO\\/2 (complete neglect of differential overlap) method was used for the study of the possibility of the quantum-chemical description of the electronic effects of substituents and heteroatoms on the CH acid properties of an extensive series of methyl derivatives of five-membered aromatic heterocycles. It is shown that the trend of the change in the relative rate constants of deuterium

N. N. Zatsepina; I. F. Tupitsyn; A. A. Kane; G. N. Sudakova

1977-01-01

66

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

67

Chemical ozone depletion during Arctic winter 1997/98 derived from ground based millimeter-wave observations  

NASA Astrophysics Data System (ADS)

We present ground based millimeter-wave measurements of Arctic stratospheric ozone at Ny-Ålesund, Spitsbergen (79N, 12E), for winter 1997/98. Vortex averaged chemical ozone depletion rates around the 475 K isentropic level were derived from our observations using measured ozone trends for 20 day periods and calculations of diabatic descent inside the vortex. Back trajectory calculations for air-parcels crossing Ny-Ålesund show that measurements at Ny-Ålesund were representative for vortex air-masses. Significant chemical ozone depletion was observed during one period at the end of February 1998 with loss rates of 32 ppb/day around the 475 K isentropic level. During this period the loss rate was higher than in February 1997. Due to the early breakup of the polar vortex, the chemical ozone depletion stopped in March and the accumulated loss is found to be 0.64±0.2 ppm in 1997/98.

Langer, J.; Barry, B.; Klein, U.; Sinnhuber, B.-M.; Wohltmann, I.; Künzi, K. F.

68

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

PubMed Central

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

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

2013-01-01

69

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

PubMed

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

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

2014-08-01

70

Chemical synthesis, NMR analysis and evaluation on a cancer xenograft model (HL-60) of the aminosteroid derivative RM-133.  

PubMed

The aminosteroid derivative RM-133 has been reported to be a promising pro-apoptotic agent showing activity on various cancer cell lines. Following the development of solid-phase synthesis that generated a series of libraries of aminosteroid derivatives, we now report the development of a convenient liquid phase chemical synthesis of RM-133, the most promising candidate, in order to obtain sufficient quantities to proceed with the first preclinical assays. A simple and convergent six-step synthesis was designed and allowed the preparation of a gram-quantity scale of RM-133. This aminosteroid derivative was also fully characterized by NMR experiments which revealed an interesting mixture of conformers. Finally, the in vivo potency of RM-133 was evaluated on a xenograft model in nude mice with HL-60 tumors, which has resulted in the blocking of tumor progression by 57%. PMID:24486462

Maltais, René; Hospital, Audrey; Delhomme, Audrey; Roy, Jenny; Poirier, Donald

2014-04-01

71

Quantum chemical calculations to reveal the relationship between the chemical structure and the fluorescence characteristics of phenylquinolinylethynes and phenylisoquinolinylethynes derivatives, and to predict their relative fluorescence intensity  

NASA Astrophysics Data System (ADS)

In this paper the relationship between the chemical structure and fluorescence characteristics of 30 phenylquinolinylethyne (PhQE), and phenylisoquinolinylethyne (PhIE) derivatives compounds employing ab initio calculations have been elucidated. Quantum chemical calculations (6-31G) were carried out to obtain: the optimized geometry, energy levels, charges and dipole moments of these compounds, in the singlet (steady and excited states) and triplet states. The relationship between quantum chemical descriptors, and wavelength of maximum excitation and emission indicated that these two parameters have the most correlation with quantum chemical hardness ( ?). Also, stokes shift has the most correlation with the square of difference between the maximum of positive charges in the singlet steady and singlet excited states. The quantitative structure-property relationship (QSPR) of PhQE and PhIE was studied for relative fluorescence intensity (RFI). The genetic algorithm (GA) was applied to select the variables that resulted in the best-fit models. After the variable selection, multiple linear regression (MLR) and support vector machine (SVM) were both utilized to construct linear and non-linear QSPR models, respectively. The SVM model demonstrated a better performance than that of the MLR model. The route mean square error (RMSE) in the training and the test sets for the SVM model was 0.195 and 0.324, and the correlation coefficients were 0.965 and 0.960, respectively, thus revealing the reliability of this model. The resulting data indicated that SVM could be used as a powerful modeling tool for QSPR studies. According to the best of our knowledge, this is the first research on QSPR studies to predict RFI for a series of PhQE and PhIE derivative compounds using SVM.

Riahi, Siavash; Beheshti, Abolghasem; Ganjali, Mohammad Reza; Norouzi, Parviz

2009-12-01

72

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

NASA Technical Reports Server (NTRS)

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.

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

73

Protein Structure Validation and Refinement Using Amide Proton Chemical Shifts Derived from Quantum Mechanics  

PubMed Central

We present the ProCS method for the rapid and accurate prediction of protein backbone amide proton chemical shifts - sensitive probes of the geometry of key hydrogen bonds that determine protein structure. ProCS is parameterized against quantum mechanical (QM) calculations and reproduces high level QM results obtained for a small protein with an RMSD of 0.25 ppm (r?=?0.94). ProCS is interfaced with the PHAISTOS protein simulation program and is used to infer statistical protein ensembles that reflect experimentally measured amide proton chemical shift values. Such chemical shift-based structural refinements, starting from high-resolution X-ray structures of Protein G, ubiquitin, and SMN Tudor Domain, result in average chemical shifts, hydrogen bond geometries, and trans-hydrogen bond (h3JNC') spin-spin coupling constants that are in excellent agreement with experiment. We show that the structural sensitivity of the QM-based amide proton chemical shift predictions is needed to obtain this agreement. The ProCS method thus offers a powerful new tool for refining the structures of hydrogen bonding networks to high accuracy with many potential applications such as protein flexibility in ligand binding. PMID:24391900

Christensen, Anders S.; Linnet, Troels E.; Borg, Mikael; Boomsma, Wouter; Lindorff-Larsen, Kresten; Hamelryck, Thomas; Jensen, Jan H.

2013-01-01

74

Chemical investigation of commercial grape seed derived products to assess quality and detect adulteration.  

PubMed

Fundamental concerns in quality control arise due to increasing use of grape seed extract (GSE) and the complex chemical composition of GSE. Proanthocyanidin monomers and oligomers are the major bioactive compounds in GSE. Given no standardized criteria for quality, large variation exists in the composition of commercial GSE supplements. Using HPLC/UV/MS, 21 commercial GSE containing products were purchased and chemically profiled, major compounds quantitated, and compared against authenticated grape seed extract, peanut skin extract, and pine bark extract. The antioxidant capacity and total polyphenol content for each sample was also determined and compared using standard techniques. Nine products were adulterated, found to contain peanut skin extract. A wide degree of variability in chemical composition was detected in commercial products, demonstrating the need for development of quality control standards for GSE. A TLC method was developed to allow for rapid and inexpensive detection of adulteration in GSE by peanut skin. PMID:25306345

Villani, Tom S; Reichert, William; Ferruzzi, Mario G; Pasinetti, Giulio M; Simon, James E; Wu, Qingli

2015-03-01

75

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

PubMed Central

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

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

2013-01-01

76

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

PubMed

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

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

2011-11-01

77

N-coco acyl derivatives, inner salt (betaine) SUBCATEGORY II: ALKYL AMINIUM AMPHOTERICS SPONSORED CHEMICAL  

E-print Network

inner salt The High Production Volume (HPV) Challenge Program 1 was conceived as a voluntary initiative aimed at developing and making publicly available screening-level health and environmental effects information on chemicals manufactured in or imported into the United States in quantities greater than one million pounds per year. In the Challenge Program, producers and importers of HPV chemicals voluntarily sponsored chemicals; sponsorship entailed the identification and initial assessment of the adequacy of existing toxicity data/information, conducting new testing if adequate data did not exist, and making both new and existing data and information available to the public. Each complete data submission contains data on 18 internationally agreed to “SIDS” (Screening Information Data Set 1,2) endpoints that are screening-level indicators of potential hazards (toxicity) for humans or the environment. The Environmental Protection Agency’s Office of Pollution Prevention and Toxics (OPPT) is evaluating the data submitted in the HPV Challenge Program on approximately 1400 sponsored chemicals by developing hazard characterizations (HCs). These HCs consist of an evaluation of the quality and completeness of the data set provided in the Challenge Program submissions.

unknown authors

78

Chemical changes due to acid precipitation in a loess-derived soil in central Europe  

Microsoft Academic Search

In a stand of Fagus silvatica in the Solling highlands, Federal Republic of Germany, we followed the effect of acid precipitation on chemical soil state and the ion fluxes in the ecosystem between 1966 and 1979. As indicated by increasing aluminum concentration in the soil solution and an increase in organic matter storage in the forest floor, for example, the

B. Ulrich; R. Mayer; P. K. Khanna

1980-01-01

79

A mathematical basis for plant patterning derived from physico-chemical phenomena.  

PubMed

The position of leaves and flowers along the stem axis generates a specific pattern, known as phyllotaxis. A growing body of evidence emerging from recent computational modeling and experimental studies suggests that regulators controlling phyllotaxis are chemical, e.g. the plant growth hormone auxin and its dynamic accumulation pattern by polar auxin transport, and physical, e.g. mechanical properties of the cell. Here we present comprehensive views on how chemical and physical properties of cells regulate the pattern of leaf initiation. We further compare different computational modeling studies to understand their scope in reproducing the observed patterns. Despite a plethora of experimental studies on phyllotaxis, understanding of molecular mechanisms of pattern initiation in plants remains fragmentary. Live imaging of growth dynamics and physicochemical properties at the shoot apex of mutants displaying stable changes from one pattern to another should provide mechanistic insights into organ initiation patterns. PMID:23386477

Beleyur, Thejasvi; Abdul Kareem, Valiya Kadavu; Shaji, Anil; Prasad, Kalika

2013-04-01

80

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

SciTech Connect

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.

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

1981-01-01

81

Sorption of heavy metal ions on new metal-ligand complexes chemically derived from Lycopodium clavatum  

SciTech Connect

Sorption of heavy metal ions from aqueous solution has been investigated as a function of pH using a novel exchanger system whereby Lycopodium clavatum is functionalized with carboxylate and glyoxime metal-ligand complexes. The new ligand exchangers were prepared using a reaction of diaminosporopollenin with various metal-ligand complexes of glyoxime and monocarboxylic acid. The sorptive behavior of these metal-ligand exchangers and the possibilities to remove and to recover selectively heavy metal cations using these systems are discussed on the basis of their chemical natures and their complexing properties.

Pehlivan, E.; Ersoz, M.; Yildiz, S. [Univ. of Selcuk, Konya (Turkey); Duncan, H.J. [Univ. of Glasgow, Scotland (United Kingdom)

1994-08-01

82

Chemically authentic surrogate mixture model for the thermophysical properties of a coal-derived liquid fuel  

SciTech Connect

We developed a surrogate mixture model to represent the physical properties of a coal-derived liquid fuel using only information obtained from a gas chromatography-mass spectrometry analysis of the fuel and a recently developed 'advanced distillation curve'. We then predicted the density, speed of sound, and viscosity of the fuel and compared them to limited experimental data. The surrogate contains five components (n-propylcyclohexane, trans-decalin, {alpha}-methyldecalin, bicyclohexane, and n-hexadecane), yet comparisons to limited experimental data demonstrate that the model is able to represent the density, sound speed, and viscosity to within 1, 4, and 5%, respectively. 102 refs., 2 figs., 5 tabs.

M.L. Huber; E.W. Lemmon; V. Diky; B.L. Smith; T.J. Bruno [National Institute of Standards and Technology (NIST), Boulder, CO (United States). Physical and Chemical Properties Division

2008-09-15

83

Physico-chemical studies of fused phenanthrimidazole derivative as sensitive NLO material  

NASA Astrophysics Data System (ADS)

Heterocyclic phenanthrimidazole derivative, 2-(4-fluorophenyl)-1-p-tolyl-1H-imidazo[4,5-f] [1,10] phenanthroline (FPTIP) has been synthesized and characterised by NMR, mass and CHN analysis. The FPTIP was evaluated concerning their solvatochromic properties and molecular optical nonlinearities. Their electric dipole moment (?), polarizability (?) and hyperpolarizability (?) have been calculated theoretically and the results indicate that the extension of the ?-framework of the ligands has an effect on the NLO properties. The energies of the HOMO and LUMO levels and the molecular electrostatic potential (MEP) energy surface studies have exploited the existence of intramolecular charge transfer (ICT) within the molecule.

Jayabharathi, Jayaraman; Thanikachalam, Venugopal; Sathishkumar, Ramalingam; Jayamoorthy, Karunamoorthy

2013-01-01

84

Activation of the germ-cell potential of human bone marrow-derived cells by a chemical carcinogen  

PubMed Central

Embryonic/germ cell traits are common in malignant tumors and are thought to be involved in malignant tumor behaviors. The reasons why tumors show strong embryonic/germline traits (displaced germ cells or gametogenic programming reactivation) are controversial. Here, we show that a chemical carcinogen, 3-methyl-cholanthrene (3-MCA), can trigger the germ-cell potential of human bone marrow-derived cells (hBMDCs). 3-MCA promoted the generation of germ cell-like cells from induced hBMDCs that had undergone malignant transformation, whereas similar results were not observed in the parallel hBMDC culture at the same time point. The malignant transformed hBMDCs spontaneously and more efficiently generated into germ cell-like cells even at the single-cell level. The germ cell-like cells from induced hBMDCs were similar to natural germ cells in many aspects, including morphology, gene expression, proliferation, migration, further development, and teratocarcinoma formation. Therefore, our results demonstrate that a chemical carcinogen can reactivate the germline phenotypes of human somatic tissue-derived cells, which might provide a novel idea to tumor biology and therapy. PMID:24998261

Liu, Chunfang; Ma, Zhan; Xu, Songtao; Hou, Jun; Hu, Yao; Yu, Yinglu; Liu, Ruilai; Chen, Zhihong; Lu, Yuan

2014-01-01

85

Chemical constituents of marine algal-derived endophytic fungus Exophiala oligosperma EN-21  

NASA Astrophysics Data System (ADS)

Seven compounds (1-7) were identified from the cultivation of the endophytic fungus Exophiala oligosperma (EN-21) that was isolated from the inner tissue of the marine red alga Laurencia similis. Their structures were identified with spectroscopic and chemical methods as 2-phenoxynaphthalene ( 1), (2 S, 3 R, 4 E, 8 E)-1- O-?-D-glucopyranosyl-3-hydroxy-2-[( R)-2'-hydroxyoctadecanoyl] amino-9-methyl-4, 8-octadeca-diene ( 2), (22 E,24 R)-ergosta-7,22-dien-3?,5?,6?-triol ( 3), (22 E, 24 R)-3?, 5?, 9?-trihydroxy-ergosta-7, 22-dien-6-one ( 4), (22 E, 24 R)-5?, 6?-epoxy-ergosta-8, 22-dien-3?, 7?-diol ( 5), (22 E, 24 R)-ergosta-4, 6, 8(14), 22-tetraen-3-one ( 6), and euphorbol ( 7). This paper reports for the first time the chemical constituents of fungus Exophiala oligosperma and the discovery of compound 1 as a natural product from the fungus.

Li, Fang; Li, Ke; Li, Xiaoming; Wang, Bingui

2011-01-01

86

NMR chemical shift as analytical derivative of the Helmholtz free energy.  

PubMed

We present a theory for the temperature-dependent nuclear magnetic shielding tensor of molecules with arbitrary electronic structure. The theory is a generalization of Ramsey's theory for closed-shell molecules. The shielding tensor is defined as a second derivative of the Helmholtz free energy of the electron system in equilibrium with the applied magnetic field and the nuclear magnetic moments. This derivative is analytically evaluated and expressed as a sum over states formula. Special consideration is given to a system with an isolated degenerate ground state for which the size of the degeneracy and the composition of the wave functions are arbitrary. In this case, the paramagnetic part of the shielding tensor is expressed in terms of the g and A tensors of the electron paramagnetic resonance spin Hamiltonian of the degenerate state. As an illustration of the proposed theory, we provide an explicit formula for the paramagnetic shift of the central lanthanide ion in endofullerenes Ln@C(60), with Ln = Ce(3+), Nd(3+), Sm(3+), Dy(3+), Er(3+), and Yb(3+), where the ground state can be a strongly spin-orbit coupled icosahedral sextet for which the paramagnetic shift cannot be described by previous theories. PMID:23406104

Van den Heuvel, Willem; Soncini, Alessandro

2013-02-01

87

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

USGS Publications Warehouse

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.

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

1992-01-01

88

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

Microsoft Academic Search

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 (%

Carlos M. Monreal; Morris Schnitzer

2011-01-01

89

Physical and chemical characterizations of biochars derived from different agricultural residues  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

90

Laboratory and field evaluations of chemical and plant-derived potential repellents against Culicoides biting midges in northern Spain.  

PubMed

The efficacy of 23 compounds in repelling Culicoides biting midges (Diptera: Ceratopogonidae), particularly Culicoides obsoletus (Meigen) females, was determined by means of a Y-tube olfactometer. The 10 most effective compounds were further evaluated in landing bioassays. The six most promising compounds (including chemical and plant-derived repellents) were evaluated at 10% and 25% concentrations in field assays using Centers for Disease Control (CDC) light traps. At least three compounds showed promising results against Culicoides biting midges with the methodologies used. Whereas olfactometer assays indicated DEET at 1?µg/µL to be the most effective repellent, filter paper landing bioassays showed plant-derived oils to be better. Light traps fitted with polyester mesh impregnated with a mixture of octanoic, decanoic and nonanoic fatty acids at 10% and 25% concentrations collected 2.2 and 3.6 times fewer midges than control traps and were as effective as DEET, which is presently considered the reference standard insect repellent. The best plant-derived product was lemon eucalyptus oil. Although these have been reported as safe potential repellents, the present results indicate DEET and the mixture of organic fatty acids to be superior and longer lasting. PMID:25079042

González, M; Venter, G J; López, S; Iturrondobeitia, J C; Goldarazena, A

2014-12-01

91

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

PubMed

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

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

2012-09-01

92

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

NASA Astrophysics Data System (ADS)

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.

Miller, James Henry

93

Synthesis and Antidiabetic Evaluation of Benzenesulfonamide Derivatives  

PubMed Central

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

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

2013-01-01

94

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

SciTech Connect

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.

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

95

Chemical library subset selection algorithms: a unified derivation using spatial statistics.  

PubMed

If similar compounds have similar activity, rational subset selection becomes superior to random selection in screening for pharmacological lead discovery programs. Traditional approaches to this experimental design problem fall into two classes: (i) a linear or quadratic response function is assumed (ii) some space filling criterion is optimized. The assumptions underlying the first approach are clear but not always defendable; the second approach yields more intuitive designs but lacks a clear theoretical foundation. We model activity in a bioassay as realization of a stochastic process and use the best linear unbiased estimator to construct spatial sampling designs that optimize the integrated mean square prediction error, the maximum mean square prediction error, or the entropy. We argue that our approach constitutes a unifying framework encompassing most proposed techniques as limiting cases and sheds light on their underlying assumptions. In particular, vector quantization is obtained, in dimensions up to eight, in the limiting case of very smooth response surfaces for the integrated mean square error criterion. Closest packing is obtained for very rough surfaces under the integrated mean square error and entropy criteria. We suggest to use either the integrated mean square prediction error or the entropy as optimization criteria rather than approximations thereof and propose a scheme for direct iterative minimization of the integrated mean square prediction error. Finally, we discuss how the quality of chemical descriptors manifests itself and clarify the assumptions underlying the selection of diverse or representative subsets. PMID:11911712

Hamprecht, Fred A; Thiel, Walter; van Gunsteren, Wilfred F

2002-01-01

96

Chemical composition and cytotoxicity evaluation of essential oil from leaves of Casearia sylvestris, its main compound ?-zingiberene and derivatives.  

PubMed

Casearia sylvestris (Salicaceae), popularly known as "guaçatonga", is a plant widely used in folk medicine to treat various diseases, including cancer. The present work deals with the chemical composition as well as the cytotoxic evaluation of its essential oil, its main constituent and derivatives. Thus, the crude essential oil from leaves of C. sylvestris was obtained using a Clevenger type apparatus and analyzed by GC/MS. This analysis afforded the identification of 23 substances, 13 of which corresponded to 98.73% of the total oil composition, with sesquiterpene a-zingiberene accounting for 50% of the oil. The essential oil was evaluated for cytotoxic activity against several tumor cell lines, giving IC50 values ranging from 12 to 153 mg/mL. Pure a-zingiberene, isolated from essential oil, was also evaluated against the tumor cell lines showing activity for HeLa, U-87, Siha and HL60 cell lines, but with IC50 values higher than those determined for the crude essential oil. Aiming to evaluate the effect of the double bonds of a-zingiberene on the cytotoxic activity, partially hydrogenated a-zingiberene (PHZ) and fully hydrogenated a-zingiberene (THZ) derivatives were obtained. For the partially hydrogenated derivative only cytotoxic activity to the B16F10-Nex2 cell line (IC50 65 mg/mL) was detected, while totally hydrogenated derivative showed cytotoxic activity for almost all cell lines, with B16F10-Nex2 and MCF-7 as exceptions and with IC50 values ranging from 34 to 65 mg/mL. These results indicate that cytotoxic activity is related with the state of oxidation of compound. PMID:23966073

Bou, Diego Dinis; Lago, João Henrique G; Figueiredo, Carlos R; Matsuo, Alisson L; Guadagnin, Rafael C; Soares, Marisi G; Sartorelli, Patricia

2013-01-01

97

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

PubMed Central

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-?-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

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

1962-01-01

98

Synthesis and evaluation of resveratrol derivatives as new chemical entities for cancer.  

PubMed

Resveratrol has been shown to be active in inhibiting multistage carcinogenesis. The potential use of resveratrol in cancer chemoprevention or chemotherapy settings has been hindered by its short half-life and low bioavailability. Considering the above remarks, using resveratrol as a prototype, we have synthesized two derivatives of resveratrol. Their activity was evaluated using in vitro and in silico analysis. Biological evaluation of resveratrol analogues on U937 cells had shown that two synthesized analogues of resveratrol had higher rates of inhibition than the parental molecule at 10?M concentration. EMSA conducted for NF-kB revealed that these molecules significantly interfered in the DNA binding ability of NF-kB. It was found that these molecules suppressed the expression of TNF?, TNFR, IL-8, actin and activated the expression of FasL, FasR genes. To understand possible molecular mechanism of the action we performed docking and dynamic studies, using NF-kB as a receptor. Results showed that resveratrol, RA1 and RA2 interacted with the residues involved in DNA binding. Resveratrol analogues by interacting NF-kB might have prevented its translocation and also by interacting with the residues involved in DNA binding might have prevented the binding of NF-kB to DNA. This may be the reason for suppression of NF-kB binding to DNA. PMID:23500626

Mulakayala, Chaitanya; Babajan, B; Madhusudana, P; Anuradha, C M; Rao, Raja Mohan; Nune, Ravi Prakash; Manna, Sunil Kumar; Mulakayala, Naveen; Kumar, Chitta Suresh

2013-04-01

99

Birth of piglets derived from porcine zygotes cultured in a chemically defined medium.  

PubMed

We evaluated the in vitro development of porcine zygotes that were cultured in a novel culture medium, porcine zygote medium (PZM), under different conditions and compared to in vivo development. The viability of these zygotes to full term after culture was also evaluated by embryo transfer to recipients. Porcine single-cell zygotes were collected from gilts on Day 2 after hCG injection. Culture of zygotes in PZM containing 3 mg/ml of BSA (PZM-3) produced better results in terms of proportion of Day 6 blastocysts, Day 8 hatching rate, and numbers of inner cell mass (ICM) cells and total cells in Day 8 embryos than that in North Carolina State University (NCSU)-23 medium. In culture with PZM-3, embryo development was optimized in an atmosphere of 5% CO2:5% O2:90% N2 compared to 5% CO2 in air. The ICM and total cell numbers in Day 6 embryos cultured in PZM-3 or in PZM-3 in which BSA was replaced with 3 mg/ml of polyvinyl alcohol (PZM-4) were also greater than those of NCSU-23 but less than those developed in vivo. However, no difference was found in the ratio of ICM to total cells among embryos developed in PZM-3, PZM-4, or in vivo. When the Day 6 embryos that developed in PZM-4 (99 embryos) or in vivo (100 embryos) were each transferred into six recipients, no difference was found in the farrowing rate (83.3% for both treatments) and in the number of piglets born (33 and 42 piglets, respectively). Our results indicate that porcine zygotes can develop into blastocysts in a chemically defined medium and to full term by transfer to recipients after culture. PMID:11751272

Yoshioka, Koji; Suzuki, Chie; Tanaka, Atsushi; Anas, Idris M-K; Iwamura, Shokichi

2002-01-01

100

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

NASA Technical Reports Server (NTRS)

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.

Bansal, Narottam P.; Chen, Yuan L.

1998-01-01

101

Chemical evolution of amphiphiles: glycerol monoacyl derivatives stabilize plausible prebiotic membranes.  

PubMed

The self-assembly of simple amphiphiles like fatty acids into cell-like membranous structures suggests that such structures were available on prebiotic Earth to support the origin of cellular life. However, the composition of primitive membranes remains unclear because the physical properties of the aqueous environment in which they assembled are relatively unconstrained in terms of temperature, pH, and ionic concentrations. It seems likely that early membranes were composed of mixtures of various amphiphiles in an aqueous medium warmed by geothermal activity prevalent in the Archean era. To better understand the properties of mixed bilayers formed by binary mixtures of single-chain amphiphiles under these conditions, we conducted stability experiments, using membranes composed of various fatty acids having hydrocarbon chain length between 8 and 18 carbons, in mixtures with their glycerol monoacyl amphiphile derivatives (GMAs). The parameters investigated were critical vesicle concentration (CVC), encapsulation, and temperature-dependent stability. We found that hydrocarbon chain length and the presence of GMAs were major factors related to membrane stability. As chain length increased, GMA additions decreased the CVC of the mixtures 4- to 9-fold. Encapsulation ability also increased significantly as a function of chain length, which reduced permeation of small marker molecules. However, long exposures to temperatures in excess of 60 degrees C resulted in a total release of encapsulated solutes and extensive mixing of the membrane components between vesicles. We conclude that GMAs can significantly increase the stability of mixed amphiphile membranes, but further studies are required to establish model membranes that are stable at elevated temperatures. PMID:20041750

Maurer, S E; Deamer, D W; Boncella, J M; Monnard, P-A

2009-12-01

102

Comparison of models to analyze mortality data and derive concentration-time response relationship of inhaled chemicals.  

PubMed

The derivation of thresholds for lethal effects for inhaled chemicals is a key issue in accidental risk management because they largely determine the outcome of land use planning, among which localization of habitations in the vicinity of a factory. This derivation is generally performed on the basis of rodent lethality data analyzed by statistical models able to extrapolate effects for different times and concentrations of exposure. A model commonly used in France is the standard probit model. In this model, effects is related to exposure concentration and duration according to the Haber's law and considers that individual thresholds, corresponding to the maximum tolerated effects before dying, are log-normally distributed among the population. This approach has been criticized for its lack of biological parameters and its inability to treat data characterized by only one time of exposure. In order to improve the current state of modeling, we proposed three alternative models. Two of them (DEBtox and Haber-TKTD models) incorporate the kinetics of the chemicals. The third one (Loguniform model) is a linearization of the standard probit model. We evaluated their performance by analyzing real data and simulated data generated with each model. For data characterized by several times of exposure, the standard probit model outperformed all other models in terms of goodness of fits and estimation of parameters. For data characterized by only one time of exposure, only DEBtox model was able to fit the data and estimate parameters, provided we dispose of several observation times, typically just after exposure and a long period afterwards. PMID:20172012

Péry, Alexandre R R; Troise, A; Tissot, S; Vincent, J M

2010-06-01

103

Chemical modulation of peptoids: synthesis and conformational studies on partially constrained derivatives.  

PubMed

The high conformational flexibility of peptoids can generate problems in biomolecular selectivity as a result of undesired off-target interactions. This drawback can be counterbalanced by restricting the original flexibility to a certain extent, thus leading to new peptidomimetics. By starting from the structure of an active peptoid as an apoptosis inhibitor, we designed two families of peptidomimetics that bear either 7-substituted perhydro-1,4-diazepine-2,5-dione 2 or 3-substituted 1,4-piperazine-2,5-dione 3 moieties. We report an efficient, solid-phase-based synthesis for both peptidomimetic families 2 and 3 from a common intermediate. An NMR spectroscopic study of 2a,b and 3a,b showed two species in solution in different solvents that interconvert slowly on the NMR timescale. The cis/trans isomerization around the exocyclic tertiary amide bond is responsible for this conformational behavior. The cis isomers are more favored in nonpolar environments, and this preference is higher for the six-membered-ring derivative 3a,b. We propose that the hydrogen-bonding pattern could play an important role in the cis/trans equilibrium process. These hydrogen bonds were characterized in solution, in the solid state (i.e., by using X-ray studies), and by molecular modeling of simplified systems. A comparative study of a model peptoid 10 containing the isolated tertiary amide bond under study outlined the importance of the heterocyclic moiety for the prevalence of the cis configuration in 2a and 3a. The kinetics of the cis/trans interconversion in 2a, 3a, and 10 was also studied by variable-temperature NMR spectroscopic analysis. The full line-shape analysis of the NMR spectra of 10 revealed negligible entropic contribution to the energetic barrier in this conformational process. A theoretical analysis of 10 supported the results observed by NMR spectroscopic analysis. Overall, these results are relevant for the study of the peptidomimetic/biological-target interactions. PMID:21611988

Moure, Alejandra; Sanclimens, Glòria; Bujons, Jordi; Masip, Isabel; Alvarez-Larena, Angel; Pérez-Payá, Enrique; Alfonso, Ignacio; Messeguer, Angel

2011-07-01

104

Remediation of lignin and its derivatives from pulp and paper industry wastewater by the combination of chemical precipitation and ozonation.  

PubMed

In the present work the degradation of the lignin and its derivatives in the residual water of a paper industry by simple ozonation was investigated. The remediation of lignin was realized using the combination of the pre-treatment with chemical precipitation, using concentrated sulfuric acid (97.1%) at the pH 1 and 3, and of the simple ozonation of the filtered residual water at the pH 1, 3, 8 and 12. Since the high residues content (the initial chemical oxygen demand (COD) is 70,000 mg/L) in the experiments the diluted samples (1:10) were used. The previous precipitation has showed a significant effect on the reduction of the COD (77%) and color (96.1%). The sludge precipitated contents sulfolignin, which in the reaction with sulfuric acid was formed. In ozonation of the filtered residual water during 25 min at the pH 1, 3, 8 and 12 the follows by-products were formed: fumaric, maleic, malonic and formic acids. The biodegradability of the treated water in ozonation increases up 0.067-0.29. The effect of the precipitation and the ozonation conditions on the decolorization kinetics was evaluated. PMID:19464112

De los Santos Ramos, W; Poznyak, T; Chairez, I; Córdova R, I

2009-09-30

105

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

PubMed

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

Menendez-Bravo, Simón; Comba, Santiago; Sabatini, Martín; Arabolaza, Ana; Gramajo, Hugo

2014-07-01

106

Local electronic and chemical structure of oligo-acetylene derivatives formed through radical cyclizations at a surface.  

PubMed

Semiconducting ?-conjugated polymers have attracted significant interest for applications in light-emitting diodes, field-effect transistors, photovoltaics, and nonlinear optoelectronic devices. Central to the success of these functional organic materials is the facile tunability of their electrical, optical, and magnetic properties along with easy processability and the outstanding mechanical properties associated with polymeric structures. In this work we characterize the chemical and electronic structure of individual chains of oligo-(E)-1,1'-bi(indenylidene), a polyacetylene derivative that we have obtained through cooperative C1-C5 thermal enediyne cyclizations on Au(111) surfaces followed by a step-growth polymerization of the (E)-1,1'-bi(indenylidene) diradical intermediates. We have determined the combined structural and electronic properties of this class of oligomers by characterizing the atomically precise chemical structure of individual monomer building blocks and oligomer chains (via noncontact atomic force microscopy (nc-AFM)), as well as by imaging their localized and extended molecular orbitals (via scanning tunneling microscopy and spectroscopy (STM/STS)). Our combined structural and electronic measurements reveal that the energy associated with extended ?-conjugated states in these oligomers is significantly lower than the energy of the corresponding localized monomer orbitals, consistent with theoretical predictions. PMID:24387223

Riss, Alexander; Wickenburg, Sebastian; Gorman, Patrick; Tan, Liang Z; Tsai, Hsin-Zon; de Oteyza, Dimas G; Chen, Yen-Chia; Bradley, Aaron J; Ugeda, Miguel M; Etkin, Grisha; Louie, Steven G; Fischer, Felix R; Crommie, Michael F

2014-05-14

107

Lattice-matched bimetallic CuPd-graphene nanocatalysts for facile conversion of biomass-derived polyols to chemicals.  

PubMed

A bimetallic nanocatalyst with unique surface configuration displays extraordinary performance for converting biomass-derived polyols to chemicals, with potentially much broader applications in the design of novel catalysts for several reactions of industrial relevance. The synthesis of nanostructured metal catalysts containing a large population of active surface facets is critical to achieve high activity and selectivity in catalytic reactions. Here, we describe a new strategy for synthesizing copper-based nanocatalysts on reduced graphene oxide support in which the catalytically active {111} facet is achieved as the dominant surface by lattice-match engineering. This method yields highly active Cu-graphene catalysts (turnover frequency = 33-114 mol/g atom Cu/h) for converting biopolyols (glycerol, xylitol, and sorbitol) to value-added chemicals, such as lactic acid and other useful co-products consisting of diols and linear alcohols. Palladium incorporation in the Cu-graphene system in trace amounts results in a tandem synergistic system in which the hydrogen generated in situ from polyols is used for sequential hydrogenolysis of the feedstock itself. Furthermore, the Pd addition remarkably enhances the overall stability of the nanocatalysts. The insights gained from this synthetic methodology open new vistas for exploiting graphene-based supports to develop novel and improved metal-based catalysts for a variety of heterogeneous catalytic reactions. PMID:23297693

Jin, Xin; Dang, Lianna; Lohrman, Jessica; Subramaniam, Bala; Ren, Shenqiang; Chaudhari, Raghunath V

2013-02-26

108

Synthesis and evaluation of the aldolase antibody-derived chemical-antibodies targeting alpha(5)beta(1) integrin  

PubMed Central

Integrin ?5?1 is an important therapeutic target that can be inhibited using an aldolase antibody (Ab)-derived chemical-Ab (chem-Ab) for the treatment of multiple human diseases, including cancers. A fairly optimized anti-integrin ?5?1 chem-Ab 38C2-4e was obtained using an in situ convergent chemical programming (CP) approach, which minimized the time and efforts needed to develop a chem-Ab. Multiple Ab-programming agents (PAs) 4a-e could be prepared rapidly using the Cu-catalyzed alkyne-azide coupling (Cu-AAC) reaction of an ?5?1 inhibitor 2 with multiple linkers 3a-e, either before or after conjugating the linkers into Ab 38C2 binding sites. In these two-steps processes, the products after step 1 can be used in next step without performing an extensive purification or analysis of the Ab-PAs or Ab-linker conjugates affording chem-Abs 38C2-(4a-e). Flow cytometry assay was used to determine binding of the chem-Abs to U87 human glioblastoma cells expressing ?5?1 integrin, and identify 38C2-3e as the strongest binder. Further studies revealed that 38C2-3e strongly inhibited proliferation of U87 cells and tube formation of HUVEC in matrigel assay, as well as tumor growth and metastasis of 4T1 cells in vivo. PMID:23102054

Goswami, Rajib K.; Liu, Yuan; Liu, Cheng; Lerner, Richard A.; Sinha, Subhash C.

2013-01-01

109

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

NASA Astrophysics Data System (ADS)

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.

Shokry, H.

2014-02-01

110

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

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

2011-01-01

111

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

112

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

SciTech Connect

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.

Schoeters, Elke [Centre of Expertise in Environmental Toxicology, Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium)]. E-mail: elke.schoeters@vito.be; Nuijten, Jean-Marie [Centre of Expertise in Environmental Toxicology, Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Heuvel, Rosette L. van den [Centre of Expertise in Environmental Toxicology, Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Nelissen, Inge [Centre of Expertise in Environmental Toxicology, Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Witters, Hilda [Centre of Expertise in Environmental Toxicology, Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Schoeters, Greet E.R. [Centre of Expertise in Environmental Toxicology, Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Tendeloo, Vigor F.I. van [Laboratory of Experimental Hematology, Antwerp University Hospital (UZA), Wilrijkstraat 10, 2650 Edegem (Belgium); Berneman, Zwi N. [Laboratory of Experimental Hematology, Antwerp University Hospital (UZA), Wilrijkstraat 10, 2650 Edegem (Belgium); Verheyen, Geert R. [Centre of Expertise in Environmental Toxicology, Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium)

2006-10-01

113

Toxic inhibition of smooth muscle contractility by plant-derived sesquiterpenes caused by their chemically reactive alpha-methylenebutyrolactone functions.  

PubMed Central

1. Previous studies have shown that extracts of feverfew (Tanacetum parthenium) and parthenolide, a sesquiterpene alpha-methylenebutyrolactone obtained from it, inhibit smooth muscle contractility in a time-dependent, non-specific and irreversible manner. 2. The hypothesis that this toxic effect is due specifically to the presence in the sesquiterpene lactone of the potentially reactive alpha-methylene function was tested on rabbit isolated aortic ring preparations. This was done (a) by comparing the effects of two plant-derived sesquiterpene lactones purified from yellow star thistle (Centaurea solstitialis): cynaropicrin (an alpha-methylenebutyrolactone) and solstitialin 13-acetate (lacking the alpha-methylene function), and (b) by chemically inactivating the alpha-methylene functions in cynaropicrin and parthenolide by reaction with cysteine. 3. The results show that the characteristic smooth muscle inhibitory profile is demonstrated by the two alpha-methylenebutyrolactones (parthenolide and cynaropicrin), but not by the compound lacking this functional group (solstitialin 13-acetate), or by those previously active compounds in which it has been inactivated with cysteine. 4. Thus the alpha-methylene function is critical for this aspect of the toxic pharmacological profile of the sesquiterpene butyrolactones, which are natural products widely distributed in the Compositae family of flowering plants. PMID:8032668

Hay, A. J.; Hamburger, M.; Hostettmann, K.; Hoult, J. R.

1994-01-01

114

Toxic inhibition of smooth muscle contractility by plant-derived sesquiterpenes caused by their chemically reactive alpha-methylenebutyrolactone functions.  

PubMed

1. Previous studies have shown that extracts of feverfew (Tanacetum parthenium) and parthenolide, a sesquiterpene alpha-methylenebutyrolactone obtained from it, inhibit smooth muscle contractility in a time-dependent, non-specific and irreversible manner. 2. The hypothesis that this toxic effect is due specifically to the presence in the sesquiterpene lactone of the potentially reactive alpha-methylene function was tested on rabbit isolated aortic ring preparations. This was done (a) by comparing the effects of two plant-derived sesquiterpene lactones purified from yellow star thistle (Centaurea solstitialis): cynaropicrin (an alpha-methylenebutyrolactone) and solstitialin 13-acetate (lacking the alpha-methylene function), and (b) by chemically inactivating the alpha-methylene functions in cynaropicrin and parthenolide by reaction with cysteine. 3. The results show that the characteristic smooth muscle inhibitory profile is demonstrated by the two alpha-methylenebutyrolactones (parthenolide and cynaropicrin), but not by the compound lacking this functional group (solstitialin 13-acetate), or by those previously active compounds in which it has been inactivated with cysteine. 4. Thus the alpha-methylene function is critical for this aspect of the toxic pharmacological profile of the sesquiterpene butyrolactones, which are natural products widely distributed in the Compositae family of flowering plants. PMID:8032668

Hay, A J; Hamburger, M; Hostettmann, K; Hoult, J R

1994-05-01

115

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

PubMed

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 microM 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. PMID:16780908

Schoeters, Elke; Nuijten, Jean-Marie; Van Den Heuvel, Rosette L; Nelissen, Inge; Witters, Hilda; Schoeters, Greet E R; Van Tendeloo, Vigor F I; Berneman, Zwi N; Verheyen, Geert R

2006-10-01

116

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

117

Toxic chemicals, including aromatic and chlorinated hydrocarbons and their derivatives, and liver lesions in white croaker (Genyonemus lineatus) from the vicinity of Los Angeles  

SciTech Connect

High concentrations of toxic chemicals in sediment and white croaker (Genyonemus lineatus), as well as liver diseases (e.g., carcinomas) in this species, were found in the Los Angeles area. The highest concentrations of aromatic hydrocarbons (AHs) in the sediment were in San Pedro Bay, and the highest concentrations of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) derivatives were in sediment from near the White Point sewer outfall. Concentrations of AHs, polychlorobiphenyls (PCBs), and DDT derivatives were generally higher in food organisms from the croaker's stomach than in sediment. Moreover, croaker from San Pedro Bay and White Point were substantially contaminated with DDT derivatives and metabolites of aromatic compounds, compared to croaker from the Hyperion outfall and Dana Point. The evidence suggest that the observed pathological conditions of the liver were associated with exposure of the croaker to toxic chemicals, which occurred, at least in part, through the ingestion of contaminated food organisms.

Malins, D.C.; McCain, B.B.; Brown, D.W.; Myers, M.S.; Krahn, M.M.; Chan, S.L.

1987-08-01

118

Assessment of the Amur River Ecosystem Pollution with Benzene and Its Derivatives Caused by an Accident at the Chemical Plant in Jilin City, China  

Microsoft Academic Search

Assessment of concentrations of benzene and its derivatives in the Amur water and fish caught in summer and autumn 2006 was\\u000a carried out after Jilin chemical plant accident (winter 2005) in the People’s Republic of China. Fish sampling of Leiocassis ussuriensis conducted in the Amur River near Khabarovsk identified benzene, toluene, ethylbenzene, isopropylbenzene, xylene reaching\\u000a to 16, 98.7, 55, 54,

S. I. Levshina; N. N. Efimov; V. N. Bazarkin

2009-01-01

119

Effect of multi-coating process on the orientation and microstructure of lead zirconate titanate (PZT) thin films derived by chemical solution deposition  

Microsoft Academic Search

This paper describes the effects of multi-coating processes on the orientation, microstructure and electrical property of lead zirconate titanate (PZT) thick films derived by chemical solution deposition. PZT thick films (>1 ?m in thickness) were deposited by various multi-coating processes, such as layer-by-layer crystallization, seed-layering or single-crystallization. The orientation and microstructure of the thick films were characterized by X-ray diffractometry

T. Kobayashi; M. Ichiki; J. Tsaur; R. Maeda

2005-01-01

120

O-Succinyl-L-homoserine-based C4-chemical production: succinic acid, homoserine lactone, ?-butyrolactone, ?-butyrolactone derivatives, and 1,4-butanediol.  

PubMed

There has been a significant global interest to produce bulk chemicals from renewable resources using engineered microorganisms. Large research programs have been launched by academia and industry towards this goal. Particularly, C4 chemicals such as succinic acid (SA) and 1,4-butanediol have been leading the path towards the commercialization of biobased technology with the effort of replacing chemical production. Here we present O-Succinyl-L-homoserine (SH) as a new, potentially important platform biochemical and demonstrate its central role as an intermediate in the production of SA, homoserine lactone (HSL), ?-butyrolactone (GBL) and its derivatives, and 1,4-butanediol (BDO). This technology encompasses (1) the genetic manipulation of Escherichia coli to produce SH with high productivity, (2) hydrolysis into SA and homoserine (HS) or homoserine lactone hydrochloride, and (3) chemical conversion of either HS or homoserine lactone HCL (HSL·HCl) into drop-in chemicals in polymer industry. This production strategy with environmental benefits is discussed in the perspective of targeting of fermented product and a process direction compared to petroleum-based chemical conversion, which may reduce the overall manufacturing cost. PMID:25155257

Hong, Kuk-Ki; Kim, Jeong Hyun; Yoon, Jong Hyun; Park, Hye-Min; Choi, Su Jin; Song, Gyu Hyeon; Lee, Jea Chun; Yang, Young-Lyeol; Shin, Hyun Kwan; Kim, Ju Nam; Cho, Kyung Ho; Lee, Jung Ho

2014-10-01

121

High grade activated carbon matting derived from the chemical activation and pyrolysis of natural fibre textile waste  

Microsoft Academic Search

Waste generated as a by-product of the production and use of natural fibres in the textile industry is typically over 50wt.% and is normally landfilled. In this research, flax and hemp natural fibres have been manufactured into a non-woven, pre-formed matting material and subsequently treated via chemical activation and pyrolysis to produce activated carbon. The influence of chemical activation process

Paul T. Williams; Anton R. Reed

2004-01-01

122

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.  

PubMed

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?M of each tetracycline-derived compound 20 min prior to exposure to 500?M iodoacetic acid plus 1mM KCN (chemical hypoxia). In other experiments, hepatocytes were incubated in anoxic Krebs-Ringer-HEPES buffer at pH6.2 for 4h prior to reoxygenation at pH7.4 (simulated I/R). Tetracycline-derived compounds were added 20 min prior to reperfusion. Ca(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(2+) uptake and suppressed the Ca(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(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. PMID:24012766

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

2013-11-15

123

Chemical Profiles and Identification of Key Compound Caffeine in Marine-Derived Traditional Chinese Medicine Ostreae concha  

PubMed Central

To compare the chemical differences between the medicinal and cultured oyster shells, their chemical profiles were investigated. Using the ultra performance liquid chromatography-electron spraying ionization-mass spectrometry (UPLC-ESI-MS), combined with principal component analysis (PCA) and orthogonal projection to latent structures discriminant analysis (OPLS-DA), the discrimination of the chemical characteristics among the medicinal and cultured oyster shells was established. Moreover, the chemometric analysis revealed some potential key compounds. After a large-scale extraction and isolation, one target key compound was unambiguously identified as caffeine (1) based on extensive spectroscopic data analysis (1D and 2D NMR, MS, and UV) and comparison with literature data. PMID:22822365

Yang, Xue; Zhou, Shi-Lu; Ma, Ai-Cui; Xu, Hai-Tao; Guan, Hua-Shi; Liu, Hong-Bing

2012-01-01

124

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

PubMed Central

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

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

1996-01-01

125

Partial Atomic Charge Derivation of small molecule Partial atomic charge is very crucial for computing physical, chemical and biological  

E-print Network

Partial Atomic Charge Derivation of small molecule Partial atomic charge is very crucial of the atomic charge in a given species, it is possible to predict the stability, solvation energetics atomic charges from experiment. Also, there is no universally agreed upon best procedure for computing

Jayaram, Bhyravabotla

126

Organometallic derivatives of furan. LII. Synthesis of carbofunctional furylsilanes and their /sup 1/H, /sup 13/C, and /sup 29/Si NMR spectroscopic and quantum-chemical investigation  

SciTech Connect

Under the standard conditions for the synthesis of furan compounds it is possible to obtain the carbofunctional derivatives of silylated furfural with retention of the trimethylsilyl group in the ring. By NMR and CNDO/2 LCAO MO methods and also as a result of the investigation of the chemical characteristics of silylated furfural and its carbofunctional derivatives it was established that the introduction of a trimethylsilyl group at position 5 of the furan ring does not change the reactivity of the carbofunctional substituents at position 2. The electronic effects of the substituents are hardly transmitted through the furan ring at all. The effect of substituents in the carbofunctional furylsilanes on the electronic structure of the ring is additive.

Lukevits, E.; Erchak, N.P.; Castro, I.; Popelis, Yu.Yu.; Kozyrev, A.K.; Anoshkin, V.I.; Kovalev, I.F.

1986-03-10

127

In situ measurement of the infrared absorption and extinction of chemical and biologically derived aerosols using flow-through photoacoustics  

NASA Astrophysics Data System (ADS)

In an effort to establish a more reliable set of optical cross sections for a variety of chemical and biological aerosol simulants, we have developed a flow-through photoacoustic system that is capable of measuring absolute, mass-normalized extinction and absorption cross sections. By employing a flow-through design we avoid issues associated with closed aerosol photoacoustic systems and improve sensitivity. Although the results shown here were obtained for the tunable CO2 laser waveband region, i.e., 9.20-10.80 ?m, application to other wavelengths is easily achievable. The aerosols considered are categorized as biological, chemical, and inorganic in origin, i.e., Bacillus atrophaeus endospores, dimethicone silicone oil (SF-96 grade 50), and kaolin clay powder (alumina and silicate), respectively. Results compare well with spectral extinction measured previously by Fourier-transform infrared spectroscopy. Comparisons with Mie theory calculations based on previously published complex indices of refraction and measured size distributions are also presented.

Gurton, Kristan P.; Dahmani, Rachid; Ligon, David; Bronk, Burt V.

2005-07-01

128

Detection of D-erythro and L-threo sphingosine bases in preparative sphingosylphosphorylcholine and its N-acylated derivatives and some evidence of their different chemical configurations.  

PubMed

Sphingosylphosphorylcholine prepared from native sphingomyelin by the Kaller procedure was found to comprise about 70% of the L-threo (2S, 3S) isomer and 30% of the D-erythro (2S, 3R) isomer. This analytical result was obtained by gas-liquid chromatography (GLC) of trimethylsilyl derivatives of N-acetylsphingosines which were prepared by enzymatic hydrolysis of synthetic N-acetylsphingosylphosphorylcholines with Clostridium perfringens phospholipase C. Some other evidence of the different chemical configuration between the erythro and threo isomers of synthetic N-acylated sphingosylphosphorylcholines was also provided by thin layer chromatography (TLC), optical rotatory dispersion (ORD), and fast atom bombardment (FAB) mass spectrometry. PMID:6654881

Hara, A; Taketomi, T

1983-11-01

129

Sequential-refining of crude glycerol derived from waste used-oil methyl ester plant via a combined process of chemical and adsorption  

Microsoft Academic Search

A sequential stage physico-chemical refining of crude glycerol, derived from a waste used-oil utilizing biodiesel (methyl ester) production plant, was performed by acidification, polar solvent extraction and activated carbon adsorption at a laboratory scale and ambient temperature. The effect of varying the acid type (H3PO4, H2SO4 and CH3COOH) and pH (1–6), the type of polar solvent (CH3OH, C2H5OH and C3H7OH)

Rudemas Manosak; Siripong Limpattayanate; Mali Hunsom

2011-01-01

130

Atomic emission detection for the quantitation of trimethylsilyl derivatives of chemical-warfare-agent related compounds in environmental samples  

Microsoft Academic Search

Quantitation of nerve agent degradation products is needed to develop methods for analysis of environmental samples for verification of the Chemical Weapons Convention. A procedure has been characterized which involves formation of the trimethylsilyl esters of alkylmethylphosphonic acids using 1% trimethylchlorosilane in bis-(trimethylsilyl)trifluoroacetamide as a derivatizing agent. Eight phosphorus-containing acids were extracted from spiked water, wipes, and two soil samples

William R. Creasy; Alex A. Rodríguez; Robert W. Warren

1995-01-01

131

Chemical actions of ionizing radiation on oligopeptide derivatives of glycine in the neutral (Zwitterion) and basic forms  

SciTech Connect

Effects of protonation of the terminal NH/sub 2/ group on the relative yields of reductive deamination and deamidation by e/sup -/ in the ..gamma..-radiolysis of di, tri and tetra glycine in the solid state are described. The experimental data provide direct chemical evidence of specific sites of addition of e/sup -/ to c = o bonds along the peptide chain.

Garrison, W.M.; Sokol, H.A.

1980-01-01

132

Organic Field-Effect Transistors with Gate Dielectric Films of Poly-p-Xylylene Derivatives Prepared by Chemical Vapor Deposition  

Microsoft Academic Search

We have fabricated organic field-effect transistors (OFETs) using various dielectric films of poly-p-xylylene derivatives to investigate the correlation of field-effect mobility and the surface properties of the dielectric films under constant conditions of fabrication process and molecular backbone. The OFET using pentacene as the semiconductor and poly-chloro-p-xylylene as the dielectric film showed good performance for an OFET using a polymer

Takeshi Yasuda; Katsuhiko Fujita; Hiroshi Nakashima; Tetsuo Tsutsui

2003-01-01

133

A rapid screening for cytochrome P450 catalysis on new chemical entities: cytochrome P450 BM3 and 1,2,5-oxadiazole derivatives.  

PubMed

This work presents the validation of a rapid screening procedure for the catalysis of cytochrome P450 on new chemical entities. The assay is tested on the prototypical, catalytically self-sufficient and soluble cytochrome P450 BM3 from Bacillus megaterium that shares a high degree of homology with mammalian counterparts. The so-called alkali assay developed in our laboratory is validated here also by product formation and molecular modeling on a number of derivatives sharing the molecular scaffold of the 1,2,5-oxadiazole ring, a class of molecules very different from the long-chain fatty acids known to be oxidized by cytochrome P450 BM3. The alkali assay reveals the ability of this cytochrome to oxidize NADPH in the presence of nine out of thirteen 1,2,5-oxadiazole derivatives tested. The enzyme shows high affinity and coupling efficiencies when incubated with four 1,2,5-oxadiazole derivatives. The presence of oxidation products deriving from catalysis was also confirmed by high-performance liquid chromatography (HPLC). Molecular docking suggests that a key factor for the 1,2,5-oxadiazole derivatives to enter the active site and induce catalysis is the presence of the -SO(2) moiety bridging the 1,2,5-oxadiazole and phenyl rings. These data indicate that the alkali assay is able to quickly and cheaply detect the recognition of new substrates by cytochrome P450. The assay is not intended to substitute HPLC-mass spectrometry analysis, but it is a preliminary screening that allows elimination of obvious nonsubstrates from the start. PMID:22983164

Tsotsou, Georgia E; Di Nardo, Giovanna; Sadeghi, Sheila J; Fruttero, Roberta; Lazzarato, Loretta; Bertinaria, Massimo; Gilardi, Gianfranco

2013-02-01

134

Chemical inhibitors suggest endophytic fungal paclitaxel is derived from both mevalonate and non-mevalonate-like pathways.  

PubMed

Taxus trees possess fungal endophytes reported to produce paclitaxel. Inhibitors that block early steps in plant paclitaxel biosynthesis were applied to a paclitaxel-producing fungus to determine whether these steps are shared. The plant paclitaxel backbone is reportedly derived from the non-mevalonate terpenoid pathway, while the side chain is phenylalanine-derived. Evidence that the shikimate pathway contributes to fungal paclitaxel was shown by decreased paclitaxel accumulation following inhibition of phenylalanine ammonia lyase. Expression of another shikimate pathway enzyme, 3-dehydroquinate synthase, coincided with paclitaxel production. The importance of the mevalonate pathway in fungal paclitaxel biosynthesis was shown by inhibition of fungal paclitaxel accumulation using compactin, a specific inhibitor of 3-hydroxy-3-methyl-glutaryl-CoA reductase. Expression of another mevalonate pathway enzyme, 3-hydroxy-3-methyl-glutaryl-CoA synthase, coincided with fungal paclitaxel accumulation. Unexpectedly, results from using fosmidomycin suggested that fungal paclitaxel requires 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), an enzyme in the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway normally found in bacteria/plants. Additional lines of evidence support this finding; first, a plant DXR antibody recognized a fungal peptide of the correct size; second, expression of an apparent fungal DXR ortholog correlated to changes in paclitaxel production; finally, BLAST searching identified a gene putatively encoding 1-deoxy-D-xylulose-5-phosphate synthase, the first enzyme in the MEP pathway in Aspergillus. PMID:22103292

Soliman, Sameh S M; Tsao, Rong; Raizada, Manish N

2011-12-27

135

Reprogramming of bone marrow-derived mesenchymal stem cells into functional insulin-producing cells by chemical regimen  

PubMed Central

Beta-cell transplantation is considered to be the most effective approach to cure type 1 diabetes (T1D). Unfortunately, the scarce availability of donor tissue limits the applicability of this therapy. Recent stem cell research progress shows stem cell therapy may be a potential means to solve this problem. Bone marrow-derived mesenchymal stem cells (MSCs) are self-renewable and multipotent adult stem cells which can differentiate into the three germ layers. Here we aimed to investigate whether MSCs could be reprogrammed into insulin-producing cells (IPCs). We isolated and characterized MSCs obtained from rat bone marrow. Then MSCs were induced to transdifferentiate into IPCs under specific conditions containing high concentrations of glucose, activin A, all-trans retinoic acid, and other maturation factors. The induced cells expressed multiple genes related to pancreatic beta-cell development and function, such as insulin1, glucagon, Pdx1, Pax6, and Glut-2. Insulin1 and C-peptide production were identified by immunocytochemistry. In vitro glucose challenge studies showed the induced cells secreted insulin in a glucose-dependent manner, as do normal pancreatic beta-cells. Transplantation of these MSC-derived insulin-positive cells could reverse the hyperglycemia of streptozotcin (STZ)-induced diabetic rats. These results demonstrated that MSCs could be reprogrammed into IPCs and might be a potential autologous cell source for transplantation therapy of T1D. PMID:23671804

Wang, Qiwei; Ye, Lingling; Liu, Hong; Liu, Xingmao; Li, Shichong; Chen, Zhaolie

2012-01-01

136

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

SciTech Connect

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.

Shiquan Tao

2006-12-31

137

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

PubMed

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

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

138

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

PubMed

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

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

2013-10-01

139

Structure and physico-chemical properties of hexadentate Schiff base zinc complexes derived from salicylaldehydes and triethylenetetramine*1  

NASA Astrophysics Data System (ADS)

Two hexadentate Schiff base zinc complexes, ZnSal 2trien and ZnVan 2trien, where Sal=salicylaldehyde, Van= o-vanillin, and trien=triethylenetetramine, have been synthesized by the reaction between salicylaldehydes, triethylenetetramine and zinc acetate. The structure of ZnSal 2trien and ZnVan 2trien were determined by single crystal X-ray crystallography. It was found that both ZnSal 2trien and ZnVan 2trien have a bent-shaped structure. Properties of the complexes were examined using differential scanning calorimetry, polarized optical microscopy and small angle X-ray scattering. Protonation constants of the ligands Sal 2trien and Van 2trien and stability constants of their zinc complexes were determined by potentiometric titration. Binding energies of ZnSal 2trien and ZnVan 2trien complexes were obtained by quantum chemical calculations.

Chantarasiri, Nuanphun; Ruangpornvisuti, Vithaya; Muangsin, Nongnuj; Detsen, Hussadee; Mananunsap, Thussanee; Batiya, Chureephon; Chaichit, Narongsak

2004-09-01

140

Analysis of cyanobacterial-derived saxitoxins using high-performance ion exchange chromatography with chemical oxidation/fluorescence detection.  

PubMed

A single run HPLC method utilizing ion exchange as the separation mode with a novel mobile phase system coupled to chemical postcolumn oxidation and fluorescence detection has been developed and demonstrated to be applicable to the quantitative analysis of paralytic shellfish poisons (PSPs) produced by Australian cyanobacteria (Anabaena circinalis) and other cyanobacteria. Both the cyanobacterial matrix and natural water constituents did not significantly affect the performance of this method. The daily precision of this method was adequate for it to be considered as a routine analytical tool for direct PSP analysis (prePSP concentration is not required) of cyanobacterial extracts and water bodies containing PSPs (C1, C2, GTX2, GTX3, NEO, STX) in the low parts per billion concentration range (10-70 ppb). PMID:16302175

Papageorgiou, John; Nicholson, Brenton C; Linke, Thomas A; Kapralos, Con

2005-12-01

141

Synthesis and characterization of N-hydroxysuccinimide ester chemical affinity derivatives of asialoorosomucoid that covalently cross-link to galactosyl receptors on isolated rat hepatocytes  

SciTech Connect

The authors have developed chemical affinity reagents for the hepatic galactosyl receptor. Asialoorosomucoid (ASOR) was derivatized with five homobifunctional N-hydroxysuccinimide (NHS) ester cross-linkers. NHS/ASOR derivatives were synthesized, purified, and applied within 10 min to isolated rat hepatocytes at 4{degree}C. Specific binding of these {sup 125}I-labeled derivatives was {approximately}90% in the presence of either EGTA or excess ASOR. Specific cross-linking assessed by the resistance of specifically bound NHS/{sup 125}I-ASOR to release by EGTA, was 50-75% of the specifically bound ligand. The extent of specific cross-linking correlated with the average number of NHS groups per ASOR and was controlled by varying the molar ratio of cross-linker to ASOR during the synthesis. After being cross-linked with any of the NHS/{sup 125}I-ASOR derivatives, cells were washed with EGTA, solubilized in Triton X-100, and analyzed by SDA-PAGE and autoradiography. They conclude that all three receptor subunits can cross-link to ligand. They propose a model in which the native receptor is a heterohexamer composed of four subunits of RHL 1 and two subunits of RHL 2 and/or RHL 3.

Herzig, M.C.S.; Weigel, P.H. (Univ. of Texas Medical Branch, Galveston (USA))

1989-01-24

142

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

PubMed

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 ?g mL-1. Compound 8 could significantly inhibit larval settlement of Bugula neritina with an EC(50) value of 3.87 ?g 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

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

2013-01-01

143

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

PubMed Central

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 ?g mL?1. Compound 8 could significantly inhibit larval settlement of Bugula neritina with an EC50 value of 3.87 ?g 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

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

2013-01-01

144

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

PubMed

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

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

2014-04-01

145

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

PubMed

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

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

146

Liquid phase formation of alkyl- and perfluoro-phosphonic acid derived monolayers on magnesium alloy AZ31 and their chemical properties.  

PubMed

Alkyl- and perfluoro-phosphonic acid derived SAMs were successfully formed on Mg alloy by liquid phase method for the first time. The chemical and anticorrosive properties of the prepared SAMs on magnesium alloys were characterized using contact angle measurements, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and electrochemical measurements. Water contact angle measurements revealed that the maximum advancing/receding water contact angles of n-octyl (OP: CH(3)(CH(2))(7)PO(OH)(2)), n-dodecyl (DP: CH(3)(CH(2))(11)PO(OH)(2)), n-octadecyl (ODP: CH(3)(CH(2))(17)PO(OH)(2)) phosphonic acid, and 2-(perfluorohexyl)ethyl (PFEP: CF(3)(CF(2))(5)CH(2)CH(2)PO(OH)(2)) phosphonic acid were 105.1/64.7°, 108.3/69.6°, 111.9/75.2°, and 115.2/67.4° respectively. In the case of alkylphosphonic acid SAMs (OP, DP, and ODP), the advancing and receding water contact angles increased with an increase in the preparation time. The angle-resolved XPS (AR-XPS) data revealed that the film thicknesses of the OP, DP, ODP, PFEP on Mg alloy were estimated to be 0.8, 1.2, 1.7, and 1.1 nm, respectively. The XPS O 1s data support that the phosphonic acid derived SAM is covalently bound to the oxide or hydroxide surface of the Mg alloy in a monodenate or bidenate manner. Chemical stability of the alkyl- and perfluoro-phosphonic acid modified Mg alloy surfaces was investigated using aqueous solutions at pH=4.0, 7.0, and 10.0. The contact angles of OP, DP, and PFEP modified Mg surface decreased rapidly within the first 5 min after immersion in all the aqueous solutions and were less than 20°. On the other hand, the contact angles of the ODP modified Mg alloy after immersion in aqueous solutions at pH 4, 7 and 10 for 5 min were 45.1°, 89.3,° and 85.5°, respectively. The ODP modified Mg alloy had highest chemical stability in four types of the phosphonic acid derived SAMs used in this study, indicating that the molecular density of ODP on Mg alloy would be higher than those of OP, DP, PFEP on Mg alloy. The corrosion resistance of ODP modified Mg alloy was investigated by potentiodynamic polarization curve measurements. The ODP modified Mg alloy exhibits protective properties in a solution containing Cl(-) ions compared to unmodified Mg alloy. PMID:21565354

Ishizaki, Takahiro; Teshima, Katsuya; Masuda, Yoshitake; Sakamoto, Michiru

2011-08-01

147

Assessment of the Amur River ecosystem pollution with benzene and its derivatives caused by an accident at the chemical plant in Jilin City, China.  

PubMed

Assessment of concentrations of benzene and its derivatives in the Amur water and fish caught in summer and autumn 2006 was carried out after Jilin chemical plant accident (winter 2005) in the People’s Republic of China. Fish sampling of Leiocassis ussuriensis conducted in the Amur River near Khabarovsk identified benzene, toluene, ethylbenzene, isopropylbenzene, xylene reaching to 16, 98.7, 55, 54, and 206 ?g kg?1, respectively. For Hypophthalmichtys molitrix Valenciennes sampled in the lower reaches of the Amur benzene, toluene, ethylbenzene, xylene were found in amounts to 9, 15.4, 16 ?g kg?1, and, benzene and xylene reaching 6 and 16 ?g kg?1 were found in Huso dauricus and benzene and xylene of 2–6 and 13–16 ?g kg?1, respectively, in Acipenser schrenckii. The above toxicants were not detected in the Amur water near the river mouth in autumn 2006. PMID:19572090

Levshina, S I; Efimov, N N; Bazarkin, V N

2009-12-01

148

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

PubMed Central

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

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

2013-01-01

149

Flavonols and derivatives of gallic acid from young leaves of Toona sinensis (A. Juss.) Roemer and evaluation of their anti-oxidant capacity by chemical methods  

PubMed Central

Background: Toona sinensis (A. Juss.) Roemer is an endemic species of Toona genus native to Asia. Its crude extract exhibits an effective anti-oxidant capacity against oxidative models, but the intrinsic substances responsible for this capacity in the extract remains unclear and is yet to be studied comprehensively. Objective: To investigate the chemical constituents of the young leaves of Toona sinensis and its anti-oxidant capacity. Materials and Methods: Silica gel column chromatography, preparative high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and mass spectrometry (MS) were used to isolate and characterize the chemical constituents. Four chemical-induced oxidative models including DPPH free-radical scavenging assay, phenazine methosulphate (PMS) nicotinamide adenine dinucleotide (NADH) PMS-NADH-NBT superoxide anion scavenging assay, FeCl3-K3Fe (CN)6 reducing power assay, and FeCl2-FerroZine metal chelation assay were applied in the present study for evaluating anti-oxidant capacity. Results: Five flavonols and three derivatives of gallic acid, including quercetrin, kaempferol-3-O-?-L-rhamopyranoside, astragalin, quercetin, kaempferol, methyl gallate, ethyl gallate, and 1, 2, 3, 4, 6-penta-O-galloyl-?-D-glucopyranose were isolated from the leaves. Results showed that these compounds exhibited various antioxidant properties, markedly either as the strong scavengers for superoxide and free radicals or as molecules that were reducing or metal chelating in nature. Conclusion: The findings suggested that the 8 compounds in the young leaves of T. sinensis that were isolated in our study were the active compounds responsible for its antioxidant activity. These compounds can be utilized as a potential health supplement, as an available source of natural antioxidants, and as an effective material in pharmaceutical applications. PMID:24914286

Yang, Huan; Gu, Qinying; Gao, Tingting; Wang, Xubo; Chue, Phenwei; Wu, Qinan; Jia, Xiaobin

2014-01-01

150

mTOR inhibitors and the anti-diabetic biguanide metformin: new insights into the molecular management of breast cancer resistance to the HER2 tyrosine kinase inhibitor lapatinib (Tykerb).  

PubMed

The small molecule HER2 tyrosine kinase inhibitor (TKI) lapatinib (Tykerb) is approved for the therapy of patients with HER2-positive breast carcinomas who have progressed on trastuzumab (Herceptin). Unfortunately, the efficacy of this HER2 TKI is limited by both primary (inherent) and acquired resistance, the latter typically occurring within 12 months of starting therapy. One of the key factors limiting our understanding of the mechanisms involved in lapatinib resistance is the lack of published preclinical models. We herein review lapatinib-refractory models recently developed at the bench and the survival pathways discovered. As hyperactivation of the pharmacologically targetable PI3K/mTOR/p70S6K1 axis appears to be central to the occurrence of lapatinib resistance, preclinical data showing enhanced antitumour effects when combining lapatinib with mTOR inhibitors (e.g., rapamycin analogues and NVP-BEZ235) highlight the importance of translational work to yield clinically useful regimens capable of delaying or treating lapatinib resistance. The unexpected ability of the anti-type II diabetes drug metformin to inactivate mTOR and decrease p70S6K1 activity further reveals that this biguanide, generally considered non-toxic and remarkably inexpensive, might be considered for new combinatorial lapatinib-based protocols in HER2-overexpressing breast cancer patients. PMID:19574203

Vázquez-Martín, Alejandro; Oliveras-Ferraros, Cristina; del Barco, Sonia; Martín-Castillo, Begoña; Menéndez, Javier A

2009-07-01

151

The 6Hankel asymptotic approximation for the uniform description of rainbows and glories in the angular scattering of state-to-state chemical reactions: derivation, properties and applications.  

PubMed

This paper considers the asymptotic (semiclassical) analysis of a forward glory and a rainbow in the differential cross section (DCS) of a state-to-state chemical reaction, whose scattering amplitude is given by a Legendre partial wave series (PWS). A recent paper by C. Xiahou, J. N. L. Connor and D. H. Zhang [Phys. Chem. Chem. Phys., 2011, 13, 12981] stated without proof a new asymptotic formula for the scattering amplitude, which is uniform for a glory and a rainbow in the DCS. The new formula was designated "6Hankel" because it involves six Hankel functions. This paper makes three contributions: (1) we provide a detailed derivation of the 6Hankel approximation. This is done by first generalizing a method described by G. F. Carrier [J. Fluid Mech., 1966, 24, 641] for the uniform asymptotic evaluation of an oscillating integral with two real coalescing stationary phase points, which results in the "2Hankel" approximation (it contains two Hankel functions). Application of the 2Hankel approximation to the PWS results in the 6Hankel approximation for the scattering amplitude. We also test the accuracy of the 2Hankel approximation when it is used to evaluate three oscillating integrals of the cuspoid type. (2) We investigate the properties of the 6Hankel approximation. In particular, it is shown that for angles close to the forward direction, the 6Hankel approximation reduces to the "semiclassical transitional approximation" for glory scattering derived earlier. For scattering close to the rainbow angle, the 6Hankel approximation reduces to the "transitional Airy approximation", also derived earlier. (3) Using a J-shifted Eckart parameterization for the scattering matrix, we investigate the accuracy of the 6Hankel approximation for a DCS. We also compare with angular scattering results from the "uniform Bessel", "uniform Airy" and other semiclassical approximations. PMID:24519014

Xiahou, Chengkui; Connor, J N L

2014-06-01

152

The determination of cyclophosphamide and its metabolites in blood plasma as stable trifluoroacetyl derivatives by electron capture chemical ionization gas chromatography/mass spectrometry.  

PubMed

A method is described for the determination of the antitumour drug cyclophosphamide and six stable metabolites in plasma of cancer patients, namely dechloroethyl-cyclophosphamide, 4-keto-cyclophosphamide, carboxy-phosphamide, alcophosphamide, nor-nitrogen mustard and the N-chloroethyl-1,3-oxazolidine-2-one, as methyl and/or trifluoroacetyl derivatives by single ion monitoring gas chromatography/mass spectrometry, mostly in the electron capture chemical ionization mode. The isolation of most metabolites was performed by solid-phase C-18 extraction in weakly acidic medium. The phosphoramide mustard isolated under these conditions decomposes readily to the nor-nitrogen mustard during derivatization. The original nor-nitrogen mustard and the chloroethyl-1,3-oxazolidine-2-one were isolated by liquid extraction with ethyl acetate in alkaline medium. Recoveries of 75-99% were measured using spiked blank plasma samples. Quantitation of metabolites in patient plasma samples was performed using two sets of calibration curves for the concentration ranges of 1-100 ng and 0.1-10 micrograms of metabolite per millilitre of original plasma. PMID:8148406

Momerency, G; Van Cauwenberghe, K; Slee, P H; Van Oosterom, A T; De Bruijn, E A

1994-03-01

153

Three New and Eleven Known Unusual C25 Steroids: Activated Production of Silent Metabolites in a Marine-Derived Fungus by Chemical Mutagenesis Strategy using Diethyl Sulphate  

PubMed Central

Three new (1–3) and 11 known (4–14) C25 steroids with an unusual bicyclo[4.4.1]A/B ring system were isolated by tracing newly produced metabolites in the EtOAc extract of an antitumor mutant AD-1-2 obtained by the diethyl sulphate (DES) mutagenesis of a marine-derived Penicillium purpurogenum G59. HPLC-PDAD-UV and HPLC-ESI-MS analyses indicated that the G59 strain did not produce these metabolites and the production of 1–14 in the mutant AD-1-2 extract was caused by the activation of silent metabolites in the original G59 strain by DES mutagenesis. The structures of the new compounds, named antineocyclocitrinols A (1) and B (2) and 23-O-methylantineocyclocitrinol (3), including their absolute configurations were determined by various spectroscopic methods, especially the NMR and Mo2-induced CD analyses. Compounds 1–3 provide the first examples of the C25 bicyclo[4.4.1]A/B ring steroids with the Z-configuration of 20,22-double bond. All of 1–14 weakly inhibited several human cancer cell lines to varying extents. These results provided additional examples for the successful application of the chemical mutagenesis strategy using DES to discover new compounds by activating silent metabolites in fungal isolates and supported also the effectiveness and usefulness of this new strategy. PMID:24633254

Xia, Ming-Wen; Cui, Cheng-Bin; Li, Chang-Wei; Wu, Chang-Jing

2014-01-01

154

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

SciTech Connect

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.

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

2009-01-01

155

VITAL NMR: using chemical shift derived secondary structure information for a limited set of amino acids to assess homology model accuracy.  

PubMed

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. PMID:22183804

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

2012-01-01

156

Recognizing subtle evidence for silicic magma derivation from petrochemically-similar arc crust: Isotopic and chemical evidence for the bimodal volcanic series of Gorely Volcanic Center, Kamchatka, Russia  

NASA Astrophysics Data System (ADS)

The Kamchatka Peninsula is home to some of the most prolific subduction related volcanic activity in the world. Gorely caldera and its central volcano are located in the rear of its currently active Eastern Volcanic Front. Recent work determined the presence of explosive ignimbrite eruptions sourced from Gorely volcano during the Pleistocene. We studied 32 eruptive units, including tephrochronologically-dated Holocene tephra, stratigraphically-arranged ignimbrites, as well as pre- and post-caldera lavas. We analyzed oxygen isotope ratios of pyroxene and plagioclase grains by laser fluorination, and major and trace element compositions of whole rocks. In addition, we determined 87Sr/86Sr and 143Nd/144Nd ratios of caldera-forming ignimbrite eruptions. Chemical compositions show that Gorely eruptive units range from basalt to basaltic andesite in the "Pra-Gorely" stages prior to caldera formation and the modern Gorely stages forming its current edifice. In contrast, eruptive material from earlier ignimbrites exposed at Opasny Ravine consists primarily of dacite. Whole rock analyses for Gorely indicate that silicic rocks and ignimbrites volumetrically dominate all other products, forming separate bimodal peaks in our SiO2-frequency diagram. In addition, trace element concentrations and ratios define two trends, one for more silicic and another for more mafic material. ?18Omelt values range from a low of 4.85 up to 6.22‰, where the lowest value was found in the last caldera forming eruption, suggesting incorporation of hydrothermally-altered material from earlier eruptions. 87Sr/86Sr and 143Nd/144Nd ratios range from 0.70328 to 0.70351 and from 0.51303 to 0.51309 respectively, with higher and more diverse values being characteristic of earlier ignimbrite units; again suggesting incorporation of surrounding crustal material. In contrast to these results, MELTS modeling using a variety of likely primitive basalts from Gorely shows it is possible to obtain silicic chemical compositions near the evolved ignimbrite compositions, strictly through 70-80% fractional crystallization at 1-2 kbars and NNO oxygen fugacity. The combination of light ?18O values as well as elevated 87Sr/86Sr and low 143Nd/144Nd values, in addition to the volumetric excess of silicic rocks suggest assimilation of the older and petrochemically-similar country-rocks (Karymshina volcano and/or the underlying Akhomten Massif). This research can be utilized for studies of other volcanoes at "long-term centers", underscoring the importance of using both isotopes and modeling of fractional crystallization to determine silicic magma derivation through coupled shallow crustal assimilation of similar older material and fractional crystallization.

Seligman, A. N.; Bindeman, I. N.; Ellis, B. S.; Ponomareva, V.; Leonov, V.

2012-12-01

157

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

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.

Maroni, Paola [Istituto Ortopedico Galeazzi, Milano (Italy)] [Istituto Ortopedico Galeazzi, Milano (Italy); Brini, Anna Teresa [Istituto Ortopedico Galeazzi, Milano (Italy) [Istituto Ortopedico Galeazzi, Milano (Italy); Dipartimento di Scienze Biomediche, Chirurgiche ed Odontoiatriche, Universita degli Studi di Milano, Milano (Italy); Arrigoni, Elena [Dipartimento di Scienze Biomediche, Chirurgiche ed Odontoiatriche, Universita degli Studi di Milano, Milano (Italy)] [Dipartimento di Scienze Biomediche, Chirurgiche ed Odontoiatriche, Universita degli Studi di Milano, Milano (Italy); Girolamo, Laura de [Istituto Ortopedico Galeazzi, Milano (Italy)] [Istituto Ortopedico Galeazzi, Milano (Italy); Niada, Stefania [Istituto Ortopedico Galeazzi, Milano (Italy) [Istituto Ortopedico Galeazzi, Milano (Italy); Dipartimento di Scienze Biomediche, Chirurgiche ed Odontoiatriche, Universita degli Studi di Milano, Milano (Italy); Matteucci, Emanuela; Bendinelli, Paola [Dipartimento di Scienze Biomediche per la Salute, Molecular Pathology Laboratory, Universita degli Studi di Milano, Milano (Italy)] [Dipartimento di Scienze Biomediche per la Salute, Molecular Pathology Laboratory, Universita degli Studi di Milano, Milano (Italy); Desiderio, Maria Alfonsina, E-mail: a.desiderio@unimi.it [Dipartimento di Scienze Biomediche per la Salute, Molecular Pathology Laboratory, Universita degli Studi di Milano, Milano (Italy)

2012-11-16

158

Transformation of quercitols into 4-methylenecyclohex-5-ene-1,2,3-triol derivatives, precursors for the chemical chaperones N-octyl-4-epi-?-valienamine (NOEV) and N-octyl-?-valienamine (NOV).  

PubMed

(+)-proto-Quercitol (1) and (-)-vibo-quercitol (2), both of which could be readily prepared by the bioconversion of myo-inositol, were successfully converted into the corresponding 4-methylenecyclohex-5-ene-1,2,3-triol derivatives. These compounds were demonstrated to be suitable precursors, preserving their configurations, for bioactive carba-aminosugars such as the potent chemical chaperone drug candidates, N-octyl-4-epi-?-valienamine (NOEV, 3) and N-octyl-?-valienamine (NOV, 4). PMID:22001090

Kuno, Shinichi; Takahashi, Atsushi; Ogawa, Seiichiro

2011-12-01

159

Chemical Evolution  

E-print Network

In this series of lectures we first describe the basic ingredients of galactic chemical evolution and discuss both analytical and numerical models. Then we compare model results for the Milky Way, Dwarf Irregulars, Quasars and the Intra-Cluster- Medium with abundances derived from emission lines. These comparisons allow us to put strong constraints on the stellar nucleosynthesis and the mechanisms of galaxy formation.

Francesca Matteucci

2007-04-05

160

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)

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.

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

2014-11-01

161

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)

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.

Tao, Shiquan

2010-04-01

162

Ru-catalyzed asymmetric hydrogenation of 3-oxoglutaric acid derivatives via solvent-assisted pinpoint recognition of carbonyls in close chemical propinquity.  

PubMed

Upon comparison of hydrogenation rates of various ?-ketocarboxylic acid derivatives, ?-ketoamides were found to be hydrogenated slightly faster than ?-ketoesters in EtOH in the presence of [RuCl(benzene)(S)-SunPhos]Cl at 70 °C with 20 bar of hydrogen. In THF these differences were so sharpened that ?-ketoamides were hydrogenated even faster than in EtOH while the esters were extremely slow. Based on these findings, a series of 3-oxoglutaric acid derived with ester and amide moieties on the two ends were hydrogenated to 3-hydroxyl products with high enantioselectivities. PMID:21728297

Li, Wanfang; Ma, Xin; Fan, Weizheng; Tao, Xiaoming; Li, Xiaoming; Xie, Xiaomin; Zhang, Zhaoguo

2011-08-01

163

A conformational ensemble derived using NMR methyl chemical shifts reveals a mechanical clamping transition that gates the binding of the HU protein to DNA.  

PubMed

Recent improvements in the accuracy of structure-based methods for the prediction of nuclear magnetic resonance chemical shifts have inspired numerous approaches for determining the secondary and tertiary structures of proteins. Such advances also suggest the possibility of using chemical shifts to characterize the conformational fluctuations of these molecules. Here we describe a method of using methyl chemical shifts as restraints in replica-averaged molecular dynamics (MD) simulations, which enables us to determine the conformational ensemble of the HU dimer and characterize the range of motions accessible to its flexible ?-arms. Our analysis suggests that the bending action of HU on DNA is mediated by a mechanical clamping mechanism, in which metastable structural intermediates sampled during the hinge motions of the ?-arms in the free state are presculpted to bind DNA. These results illustrate that using side-chain chemical shift data in conjunction with MD simulations can provide quantitative information about the free energy landscapes of proteins and yield detailed insights into their functional mechanisms. PMID:24517490

Kannan, Arvind; Camilloni, Carlo; Sahakyan, Aleksandr B; Cavalli, Andrea; Vendruscolo, Michele

2014-02-12

164

GC\\/MS analysis of trimethylsilyl derivatives of treaty-related chemical warfare agent degradation products. Final report, May-August 1994  

Microsoft Academic Search

The entry into force of the Chemical Weapons Convention requires specific detection methods for identification of CW agent degradation products to verify treaty compliance or noncompliance. Many of these products are polar and not detected in the original state by gas chromatography based instrumentation. In this study, 22 compounds, including 4 alkylphosphonic acids (methyl, ethyl, n-propyl, and t-butyl) and 18

Rohrbaugh

1995-01-01

165

Determination of binding strength for the supramolecular complexation of a designed bisporphyrin with C60, C70 and their derivatives employing absorption spectrophotometric, fluorescence and quantum chemical calculations.  

PubMed

The present paper reports the synthesis of a designed bisporphyrin (1), and its supramolecular complexes with C60, C70 and their derivatives, namely, tert-butyl-(1,2-methanofullerene)-61-carboxylate (2) and [6,6]-phenyl C70 butyric acid methyl ester (3) in toluene medium. C60, C70 and their derivatives undergo ground state non-covalent interaction with 1 is evidenced from absorption spectrophotometric study in which it is observed that the intensity of the Soret absorption band of 1 decreases considerably in presence of C60, C70 and their derivatives. Steady state fluorescence studies reveal efficient quenching of fluorescence of 1 in presence of fullerenes. The binding constant (K) values of the fullerene/1 complexes follows the trend: 2/1derivatives in comparison to C60 and C70. Time resolved emission studies establish relatively long-lived charge separated state for the C(70)/1 complex. Molecular mechanics calculations at force field model in vacuo evoke the single projection geometric structures of various fullerene/1 complexes and interpret their stability differences in terms of heat of formation values. PMID:21703923

Mukherjee, Sibayan; Bauri, Ajay K; Bhattacharya, Sumanta

2011-09-01

166

Chemical derivatization analysis of pesticide residues. IX. Analysis of phenol and 21 chlorinated phenols in natural waters by formation of pentafluorobenzyl ether derivatives  

Microsoft Academic Search

A sensitive, isomer-specific method is described for the simultaneous and quantitative analysis of 22 phenols (phenol, 19 chlorophenols, and 3 chloroalkylphenols) in natural waters. The sample was acidified to pH less than or equal to 2, extracted with dichloromethane, evaporated, and dissolved in acetone. The phenol extract was then reacted with pentafluorobenzyl bromide (PFBBr) to give the PFB ether derivatives.

H. B. Lee; L. D. Weng; A. S. Y. Chau

2009-01-01

167

40 CFR 721.9658 - Thiadiazole derivative.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Thiadiazole derivative. 721.9658 Section 721.9658...Substances § 721.9658 Thiadiazole derivative. (a) Chemical substance and significant...substance identified as a thiadiazole derivative (PMN P-94-1631) is subject...

2013-07-01

168

40 CFR 721.9658 - Thiadiazole derivative.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Thiadiazole derivative. 721.9658 Section 721.9658...Substances § 721.9658 Thiadiazole derivative. (a) Chemical substance and significant...substance identified as a thiadiazole derivative (PMN P-94-1631) is subject...

2011-07-01

169

40 CFR 721.5913 - Phenothiazine derivative.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Phenothiazine derivative. 721.5913 Section 721.5913...Substances § 721.5913 Phenothiazine derivative. (a) Chemical substance and significant...identified generically as a phenothiazine derivative (PMN P-96-813) is subject...

2010-07-01

170

40 CFR 721.9658 - Thiadiazole derivative.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Thiadiazole derivative. 721.9658 Section 721.9658...Substances § 721.9658 Thiadiazole derivative. (a) Chemical substance and significant...substance identified as a thiadiazole derivative (PMN P-94-1631) is subject...

2012-07-01

171

40 CFR 721.9658 - Thiadiazole derivative.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Thiadiazole derivative. 721.9658 Section 721.9658...Substances § 721.9658 Thiadiazole derivative. (a) Chemical substance and significant...substance identified as a thiadiazole derivative (PMN P-94-1631) is subject...

2010-07-01

172

40 CFR 721.5913 - Phenothiazine derivative.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Phenothiazine derivative. 721.5913 Section 721.5913...Substances § 721.5913 Phenothiazine derivative. (a) Chemical substance and significant...identified generically as a phenothiazine derivative (PMN P-96-813) is subject...

2011-07-01

173

40 CFR 721.5913 - Phenothiazine derivative.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Phenothiazine derivative. 721.5913 Section 721.5913...Substances § 721.5913 Phenothiazine derivative. (a) Chemical substance and significant...identified generically as a phenothiazine derivative (PMN P-96-813) is subject...

2013-07-01

174

Interrelationships among biological activity, disulfide bonds, secondary structure, and metal ion binding for a chemically synthesized 34-amino-acid peptide derived from ?-fetoprotein  

Microsoft Academic Search

A 34-amino-acid peptide has been chemically synthesized based on a sequence from human ?-fetoprotein. The purified peptide is active in anti-growth assays when freshly prepared in pH 7.4 buffer at 0.20 g\\/l, but this peptide slowly becomes inactive. This functional change is proven by mass spectrometry to be triggered by the formation of an intrapeptide disulfide bond between the two

Robert MacColl; Leslie E. Eisele; Robert F. Stack; Charles Hauer; Dilip D. Vakharia; Adina Benno; Wayne C. Kelly; Gerald J. Mizejewski

2001-01-01

175

Expression of transformation in cell hybrids. II. Nonsuppression of the transformed phenotype in hybrids between a chemically transformed and nontransformed derivatives of Balb/3T3.  

PubMed

Hybrid clones derived from a nitrosocarbaryl-transformed Balb/3T3 cell line, Clone H, and a nontransformed cell line THO2 resemble the transformed parent in the clone morphology, higher saturation density, colony formation in medium with reduced serum concentration, growth in agarose and ability to form clones on Balb/3T3 monolayer. Results are discussed in the framework of genetic models which permit or require dominant mutations for the expression of transformed phenotype. PMID:701383

Jha, K K; Cacciapuoti, J; Ozer, H L

1978-11-01

176

Controlling stereoselectivity by enzymatic and chemical means to access enantiomerically pure (1S,3R)-1-benzyl-2,3-dimethyl-1,2,3,4-tetrahydroisoquinoline derivatives?  

PubMed Central

A chemoenzymatic strategy for the synthesis of enantiomerically pure novel alkaloids (1S,3R)-1-benzyl-2,3-dimethyl-1,2,3,4-tetrahydroisoquinolines is presented. The key steps are the biocatalytic stereoselective reductive amination of substituted 1-phenylpropan-2-one derivatives to yield chiral amines employing microbial ?-transaminases, and the diastereoselective reduction of a Bischler–Napieralski imine intermediate by catalytic hydrogenation in the presence of palladium on charcoal, leading exclusively to the desired cis-isomer. PMID:24503964

Orden, Alejandro A.; Schrittwieser, Joerg H.; Resch, Verena; Mutti, Francesco G.; Kroutil, Wolfgang

2013-01-01

177

Micro-ion beam analysis of physico-chemical reactions at the interface between sol-gel derived glass particles in  

E-print Network

and homogeneity at low process- ing temperature6,7 . The reason for choosing a glass in the SiO2-CaO binary system-gel derived glass particles in the SiO2-CaO system and biological fluids J. Lao1 , J.M. Nedelec2 , Ph. Moretto the sensitivity of ion beam analysis methods to char- acterize in vitro the bioactive glass/biological fluids

Boyer, Edmond

178

Synthesis of New Uracil5Sulfonamide Derivatives and Immuno-Stimulatory Effect of a Chemically Modified Hemolymph of Biomphalaria alexandrina on Schistosoma mansoni Infected Mice  

Microsoft Academic Search

SomeN-p-substituted phenyl uracil-5-sulphonamide derivatives have been synthesized to be evaluated as molluscicides againstBiomphalaria alexandrina snails, the intermediate host ofSchistosoma mansoni. Schistosoma mansoni infected mice were treated with hemolymph obtained from pre-treatedBiomphalaria alexandrina snails with the products4a, 10a, 10b and4b or obtained from non-treated snails. The selection of the concentration based on the predetermined dose which caused mortality\\u000a of less than

O. A. Fathalla; M. E. Haiba; A. S. Maghraby

2003-01-01

179

Photoluminescence of methoxy and carboethoxy derivatives of 1,3-diphenyl-1 H-pyrazolo[3,4- b]quinoline: Experiment and quantum-chemical simulations  

Microsoft Academic Search

The optical absorption and photoluminescence are studied in the newly synthesized methoxy (MO) and carboethoxy (CE) diphenyl-pirazoloquinoline (DPPQ)-derivatives: 6MO[DPPQ], 6MO1pMO[DPPQ], 6MO13pMO[DPPQ] and 6CE[DPPQ]. The photoemission spectra are recorded in organic solvents of different polarities and found to be highly solvatochromic. 6MO[DPPQ] and 6CE[DPPQ] show broad emission bands shifted to the red with the increase of solvent polarity, whereas the phenyl-methoxy

S. Ca?us; E. Gondek; A. Danel; B. Jarosz; J. Nizio?; A. V. Kityk

2007-01-01

180

Derivatives Page  

NSDL National Science Digital Library

Derivatives are financial securities whose value is derived from another "underlying" financial security. Options, futures, swaps, swaptions, and structured notes are all examples of derivative securities. Derivatives can be used in hedging, protecting against financial risk, or can be used to speculate on the movement of commodity or security prices, interest rates, or the levels of financial indices. The valuation of derivatives makes use of the statistical mathematics of uncertainty. With links to related articles. See also Derivatives Concepts A-Z, glossary of derivatives-related terminology designed to make the other articles in the Financial Pipeline's Derivatives section easier to understand.

2007-03-22

181

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

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

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

2012-01-01

182

Substituent-Modulated Affinities of Halobenzene Derivatives to the HIV-1 Integrase Recognition Site. Analyses of the Interaction Energies by Parallel Quantum Chemical and Polarizable Molecular Mechanics.  

PubMed

The C-X bond of halobenzenes (X = Cl, Br) has a dual character, its electron density being depleted in its prolongation and built-up on its sides. We have recently considered three protein or nucleic acid recognition sites of halobenzenes and quantified the energy gains that either electron-attracting substituents or electron-donating ones contribute due to such a character (El Hage et al., paper in revision). Nonadditivity was found to impact the total interaction energies. We focus here on one recognition site, that of the HIV-1 integrase, in which the halobenzene ring of the drug elvitegravir is sandwiched between a guanine and a cytosine base. We perform energy-decomposition analyses of the ab initio quantum-chemistry (QC) binding energies of the parent halobenzene ring and its derivatives with this G-C base pair. In these complexes, the nonadditivity of ?E could be traced back mostly to the polarization contribution Epol. In view of large-scale applications to the entirety of the complex formed between the integrase, the viral DNA, and the whole drug, the analyses were performed in parallel with a polarizable molecular mechanics method, SIBFA. This method could faithfully reproduce most features of the QC energies. This is due to its use of QC-derived distributed multipoles and polarizabilities, which enable us to account for both nonisotropy and nonadditivity. PMID:25230384

El Hage, Krystel; Piquemal, Jean-Philip; Hobaika, Zeina; Maroun, Richard G; Gresh, Nohad

2014-10-16

183

Oligo(A), oligo(TG), and Alu repeats of DNA in chromatin are available for sequence-specific chemical modification with oligodeoxynucleotide derivatives.  

PubMed

Reaction of 4-(N-2-chloroethyl-N-methylamino) benzylphosphamides of oligonucleotides, which are targeted to the poly(A), poly(TG), and Alu repeats of eukaryotic DNA in chromatin and isolated nuclei from HeLa cells, has been investigated. It was found that the reagents alkylate DNA and some proteins due to specific complex formation. The affinity character of the reaction was proved by the fact that free corresponding oligonucleotides taken in excess or preliminary treatment of chromatin with S1 nuclease both prevent the biopolymers from the modification. Deproteinated DNA from the same cells does not react with oligonucleotide derivatives. This suggests that the chromatin DNA must have some structural features allowing oligonucleotide binding. Reactivity may be attributed to the existence of strongly negative supercoiled DNA regions containing single-stranded sequences or regions where DNA can unwind in the presence of complementary oligonucleotides. Results obtained suggest that in eukaryotic chromatin there are open DNA sequences available for affinity modification with oligonucleotide derivatives not only due to formation of triple helixes. PMID:7734940

Kobets, N D; Borissov, R G; Chernolovskaya, E L; Gorn, V V; Vlassov, V V

1994-01-01

184

Chemical defense secretions of the termite soldiers ofAcorhinotermes andRhinotermes (Isoptera, Rhinotermitinae) : Ketones, vinyl ketones, and ?-ketoaldehydes derived from fatty acids.  

PubMed

The defense secretions of advanced "nasutoid" rhinotermitine soldiers from the New World contain enolic ?-ketoaldehydes as the major components. The secretions of minor soldiers ofRhinotermes hispidus (Emerson) andR. marginalis (Emerson) consist primarily of 3-keto-13-tetradecenal and 3-ketotetradecanal, but possess in addition C13, C14, C15, and C17 saturated and unsaturated ketones. Major soldiers lacked these compounds and in fact had virtually no frontal gland secretion. The defense secretion of the monomorphic soldiers ofAcorhinotermes subfusciceps (Emerson) contains mostly 3-keto-(Z)-9-hexadecenal and (Z)-8-pentadecen-2-one. Biosynthetic origins and interrelationships are postulated for these compounds, and the concomitant evolution of chemical weaponry and the modified labral brush is discussed. PMID:24414591

Prestwich, G D; Collins, M S

1982-01-01

185

Mammalian and teleost cell line bioassay and chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent concentrations in lake trout (Salvelinus namaycush) from Lake Superior and Lake Ontario, North America  

SciTech Connect

For livers of lake trout from three Great Lakes sites, the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent concentrations (TEQs) were determined in four ways. Bioassay-derived (BD) TEQs were measured with rat (H4IIE) and rainbow trout (RTL-W1) cell lines, and chemistry-derived (CD) TEQs were calculated with TCDD equivalency factors (TEFs) derived with H4IIE and RTL-W1. Generally, BD-TEQs and CD-TEQs for individual samples did not differ significantly for either H4IIE or RTL-W1, indicating that all of the AhR-active compounds in a sample were accounted for by the congener analysis and that these compounds acted in an additive fashion in both mammalian and piscine systems. However, contributions of individual chemicals to overall CD-TEQs differed with H4IIE and RTL-W1 TEFs, and for some individual samples. TEQs did depend on the method used. Hepatic TEQs and ethoxyresorufin-O-deethylase (EROD) levels differed significantly between sites. For TEQs, the order was Glenora > Jackfish Bay > Black Bay; for EROD activity, the order was Jackfish Bay > Glenora = Black Bay. No correlation was found between hepatic TEQs and EROD activity, which suggests that the two measurements are evaluating different but related consequences of contaminant exposure.

Whyte, J.J.; Heuvel, M.R. van den; Clemons, J.H.; Dixon, D.G.; Bols, N.C. [Univ. of Waterloo, Ontario (Canada). Dept. of Biology; Huestis, S.Y. [Dept. of Fisheries and Oceans, Burlington, Ontario (Canada); Servos, M.R. [Environment Canada, Burlington, Ontario (Canada). National Water Research Inst.

1998-11-01

186

A statistical approach towards the derivation of predictive gene sets for potency ranking of chemicals in the mouse embryonic stem cell test.  

PubMed

The embryonic stem cell test (EST) is applied as a model system for detection of embryotoxicants. The application of transcriptomics allows a more detailed effect assessment compared to the morphological endpoint. Genes involved in cell differentiation, modulated by chemical exposures, may be useful as biomarkers of developmental toxicity. We describe a statistical approach to obtain a predictive gene set for toxicity potency ranking of compounds within one class. This resulted in a gene set based on differential gene expression across concentration-response series of phthalatic monoesters. We determined the concentration at which gene expression was changed at least 1.5-fold. Genes responding with the same potency ranking in vitro and in vivo embryotoxicity were selected. A leave-one-out cross-validation showed that the relative potency of each phthalate was always predicted correctly. The classical morphological 50% effect level (ID50) in EST was similar to the predicted concentration using gene set expression responses. A general down-regulation of development-related genes and up-regulation of cell-cycle related genes was observed, reminiscent of the differentiation inhibition in EST. This study illustrates the feasibility of applying dedicated gene set selections as biomarkers for developmental toxicity potency ranking on the basis of in vitro testing in the EST. PMID:24480513

Schulpen, Sjors H W; Pennings, Jeroen L A; Tonk, Elisa C M; Piersma, Aldert H

2014-03-21

187

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)

from the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS), both on board 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. We investigate applications of the three ozone data products from near-decadal and interannual time scales to day-to-day case studies. Interannual 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 interannual events including split stratospheric warmings in the Northern Hemisphere extratropics 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.

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, P. K.; Heney, M. K.

2014-05-01

188

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)

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.

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

189

Anti-inflammatory effects of methyl ursolate obtained from a chemically derived crude extract of apple peels: potential use in rheumatoid arthritis.  

PubMed

Ursolic acid (UA), a pentacyclic triterpene acid found in apple peels (Malus domestica, Borkh, Rosaceae), has a large spectrum of pharmacological effects. However, the vegetal matrix usually produces highly viscous and poorly soluble extracts that hamper the isolation of this compound. To overcome this problem, the crude EtOH-AcOEt extract of commercial apple peels was exhaustively treated with diazomethane, after which methyl ursolate (MU) was purified by column chromatography and characterized spectrometrically. The anti-inflammatory effects of UA and MU (50 mg/kg) were analyzed by zymosan-induced paw edema, pleurisy and in an experimental arthritis model. After 4 h of treatment with UA and MU, paw edema was reduced by 46 and 44 %, respectively. Both UA and MU inhibited protein extravasation into the thoracic cavity; tibio-femoral edema by 40 and 48 %, respectively; and leukocyte influx into the synovial cavity after 6 h by 52 and 73 %, respectively. Additionally, both UA and MU decreased the levels of mediators related to synovial inflammation, such as KC/CXCL-1 levels by 95 and 90 %, TNF-? levels by 76 and 71 %, and IL-1? levels by 57 and 53 %, respectively. Both the compounds were equally effective when assayed in different inflammatory models, including experimental arthritis. Hence, MU may be considered to be a useful anti-inflammatory derivative to overcome the inherent poor solubility of UA for formulating pharmaceutical products. PMID:24733672

Pádua, Tatiana A; de Abreu, Bianca S S C; Costa, Thadeu E M M; Nakamura, Marcos J; Valente, Lígia M M; Henriques, Maria das Graças; Siani, Antonio C; Rosas, Elaine C

2014-11-01

190

1,2,3-Triazole-containing derivatives of rupestonic acid: click-chemical synthesis and antiviral activities against influenza viruses.  

PubMed

Two series of rupestonic acid derivatives, (1-substituted-1H-1,2,3-triazol-4-yl)methyl 2-((5R,8S,8aS)-3,8-dimethyl-2-oxo-1,2,4,5,6,7,8,8a-octahydroazulen-5-yl)acrylate and N-(1-substituted-1H-1,2,3-triazol-4-yl)methyl 2-((5R,8S,8aS)-3,8-dimethyl-2-oxo-1,2,4,5,6,7,8,8a-octahydroazulen-5-yl)acrylamide were easily and efficiently synthesized via click chemistry. These compounds were tested for their in vitro activities against various strains of influenza A virus (H1N1, oseltamivir resistant H1N1, H3N2) and influenza B virus. The results showed that nine compounds were active against the H1N1 strain of influenza A virus and among them the best one 14a, was as active as the reference drugs, Oseltamivir and Ribavirin. Some of them were also active on the Oseltamivir resistant H1N1 strain. In regards to influenza B virus, twenty-one compounds over thirty were active and seven of them 7b, 8b, 9b, 10a, 11b, 12b, 13b showed better activity than Ribavirin. The structure-activity relationship of these compounds is discussed on the basis of each type of the viruses studied. Furthermore, four best representative compounds 7b, 10a, 12b and 14a were evaluated in a plaque assay experiment using MDCK cells and RBV as control compound and the results showed that 7b, 10a and 12b were better than RBV in inhibiting plaque formation, in good accordance with their anti-influenza B activities. PMID:24583605

He, Yao-Wu; Dong, Chang-Zhi; Zhao, Jiang-Yu; Ma, Lin-Lin; Li, Yu-Huan; Aisa, Haji Akber

2014-04-01

191

Systemic approaches identify a garlic-derived chemical, Z-ajoene, as a glioblastoma multiforme cancer stem cell-specific targeting agent.  

PubMed

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

Jung, Yuchae; Park, Heejoo; Zhao, Hui-Yuan; Jeon, Raok; Ryu, Jae-Ha; Kim, Woo-Young

2014-07-01

192

Effects of Oxide Seeding Layers on Electrical Properties of Chemical Solution Deposition-Derived Pb(Mg1/3Nb2/3)O3-PbTiO3 Relaxor Thin Films  

NASA Astrophysics Data System (ADS)

Relaxor ferroelectrics Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) have attracted considerable attention because of their excellent electrical properties, such as high dielectricity and piezoelectricity, for application to super capacitors, piezoelectric actuators, and so on. It is well known that the electrical properties of ferroelectric thin films depend on several parameters, such as crystal orientation, composition, and residual stress. In this study, the effects of the lead titanate and lanthanum nickel oxide seeding layers on the film orientation, electrical properties, and low-temperature crystallization behavior were investigated for Chemical Solution Deposition (CSD)-derived PMN-PT thin films. As a result, PMN-PT thin films with (001)C- and (111)C-preferred orientations were successfully obtained by designing the seeding layers. Both thin films exhibited very good ferroelectricity because of their good crystallinity and preferred orientation.

Arai, Takashi; Goto, Yasuyuki; Yanagida, Hiroshi; Sakamoto, Naonori; Ohno, Tomoya; Matsuda, Takeshi; Wakiya, Naoki; Suzuki, Hisao

2013-09-01

193

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

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

Chini, Maria Giovanna; Jones, Catharine R; Zampella, Angela; D'Auria, Maria Valeria; Renga, Barbara; Fiorucci, Stefano; Butts, Craig P; Bifulco, Giuseppe

2012-02-01

194

14-methyl epothilone derivatives  

US Patent & Trademark Office Database

Compounds of the invention include 14-mehtyl epothilone derivatives. More generally, preferred compounds of the invention are those that can be produced by altering the epothilone PKS genes as described herein and optionally by action of epothilone modification enzymes and/or by chemically modifying the resulting epothilones produces when those genes are expressed.

2003-06-24

195

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)

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.

Heiderscheidt, Elisangela; Ronkanen, Anna-Kaisa; Klöve, Björn

2013-04-01

196

Chemical carcinogenesis: nature's metabolic mistake  

Microsoft Academic Search

The normal biochemical defense against toxic chemicals, such as polyaromatic hydrocarbons, is to attach functional groups, such as hydroxyl, glucuronic acid, glutathione, etc. that tend to make the chemicals more water-soluble and readily excretable as harmless derivatives. However, chemical carcinogens form highly reactive intermediates on the path to final detoxification. These chemically unstable compounds, once formed, can readily attack cellular

James K. Selkirk; Michael C. MacLeod

1982-01-01

197

Gas-phase protonation and deprotonation of acrylonitrile derivatives N[triple chemical bond]C--CH==CH--X (X=CH(3), NH(2), PH(2), SiH(3)).  

PubMed

A combined experimental and theoretical study on the gas-phase basicity and acidity of a series of cyanovinyl derivatives is presented. The gas-phase basicities and acidities of (N[triple chemical bond]C--CH==CH--X, X=CH(3), NH(2)) were obtained by means of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry techniques. The corresponding calculated values were obtained at the G3B3 level of theory. The effects of exchanging CH(3) for SiH(3), and NH(2) for PH(2), were analyzed at the same level of theory. For the neutral molecules, the Z isomer is always the dominant species under standard gas-phase conditions at 298 K. The loss of the proton from the substituent X was found systematically to be much more favorable than deprotonation of the HC==CH linking group. The corresponding isomeric E ion is much more stable than the Z ion, so that only the former should be found in the gas phase. The most significant structural changes upon deprotonation occur for the methyl and amino derivatives because, in both cases, deprotonation of X leads to a significant charge delocalization in the corresponding anion. Protonation takes place systematically at the cyano group, whereby the isomeric E ion is again more stable than the Z ion. Push-pull effects explain the preference of aminoacrylonitrile to be protonated at the cyano group, which also explains the high basicity of this derivative relative to other members of the analyzed series that present rather similar gas-phase basicities, GB approximately 780 kJ mol(-1), indicating that the different nature of the substituents has only a weak effect on the intrinsic basicity of the cyano group. The cyanovinyl derivatives have a significantly stronger gas-phase acidity than that of the corresponding vinyl compounds CH(2)==CH--X. This acidity-strengthening effect of the cyano group is attributed to the greater stabilization of the anion with respect to the corresponding neutral compound. PMID:16991171

Luna, Alberto; Mó, Otilia; Yáñez, Manuel; Gal, Jean-François; Maria, P-C; Guillemin, Jean-Claude

2006-12-13

198

40 CFR 721.9740 - Brominated triazine derivative.  

Code of Federal Regulations, 2013 CFR

...triazine derivative. (a) Chemical substance and significant...to reporting. (1) The chemical substance identified generically...requirements do not apply when the chemical substance is present in a plastic...elastomer, rubber matrix, or in solution. (iii) Industrial,...

2013-07-01

199

40 CFR 721.9740 - Brominated triazine derivative.  

Code of Federal Regulations, 2012 CFR

...triazine derivative. (a) Chemical substance and significant...to reporting. (1) The chemical substance identified generically...requirements do not apply when the chemical substance is present in a plastic...elastomer, rubber matrix, or in solution. (iii) Industrial,...

2012-07-01

200

40 CFR 721.9740 - Brominated triazine derivative.  

Code of Federal Regulations, 2010 CFR

...triazine derivative. (a) Chemical substance and significant...to reporting. (1) The chemical substance identified generically...requirements do not apply when the chemical substance is present in a plastic...elastomer, rubber matrix, or in solution. (iii) Industrial,...

2010-07-01

201

40 CFR 721.9079 - Dihydro quinacridone derivative (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Dihydro quinacridone derivative (generic). 721.9079 Section... § 721.9079 Dihydro quinacridone derivative (generic). (a) Chemical substance...identified generically as dihydro quinacridone derivative (PMN P-01-397) is subject...

2010-07-01

202

40 CFR 721.10368 - Triphenodioxazine derivatives (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Triphenodioxazine derivatives (generic). 721.10368 Section... § 721.10368 Triphenodioxazine derivatives (generic). (a) Chemical substance...identified generically as triphenodioxazine derivatives (PMN P-10-84) is subject...

2013-07-01

203

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2010 CFR

... Substituted phenylimino carbamate derivative. 721.2025 Section 721.2025... Substituted phenylimino carbamate derivative. (a) Chemical substance and significant...as a substituted phenylimino carbamate derivative (PMN P-91-487) is subject...

2010-07-01

204

40 CFR 721.646 - Aminofluoran derivative (generic name).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Aminofluoran derivative (generic name). 721.646 Section...Substances § 721.646 Aminofluoran derivative (generic name). (a) Chemical...identified generically as aminofluoran derivative (PMN P-95-512) is subject...

2010-07-01

205

40 CFR 721.10172 - Alkylamide derivative (generic).  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false Alkylamide derivative (generic). 721.10172 Section...Substances § 721.10172 Alkylamide derivative (generic). (a) Chemical substance...identified generically as alkylamide derivative (PMN P-03-633) is subject...

2011-07-01

206

40 CFR 721.1760 - Substituted benzotriazole derivatives.  

Code of Federal Regulations, 2013 CFR

... false Substituted benzotriazole derivatives. 721.1760 Section 721.1760...721.1760 Substituted benzotriazole derivatives. (a) Chemical substances and significant...generically as substituted benzotriazole derivatives (PMNs P-93-374 and...

2013-07-01

207

40 CFR 721.1760 - Substituted benzotriazole derivatives.  

Code of Federal Regulations, 2012 CFR

... false Substituted benzotriazole derivatives. 721.1760 Section 721.1760...721.1760 Substituted benzotriazole derivatives. (a) Chemical substances and significant...generically as substituted benzotriazole derivatives (PMNs P-93-374 and...

2012-07-01

208

40 CFR 721.10330 - Pyrazolone derivative (generic).  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Pyrazolone derivative (generic). 721.10330 Section...Substances § 721.10330 Pyrazolone derivative (generic). (a) Chemical substance...identified generically as pyrazolone derivative (PMN P-03-722) is subject...

2012-07-01

209

40 CFR 721.10172 - Alkylamide derivative (generic).  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Alkylamide derivative (generic). 721.10172 Section...Substances § 721.10172 Alkylamide derivative (generic). (a) Chemical substance...identified generically as alkylamide derivative (PMN P-03-633) is subject...

2010-07-01

210

40 CFR 721.646 - Aminofluoran derivative (generic name).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Aminofluoran derivative (generic name). 721.646 Section...Substances § 721.646 Aminofluoran derivative (generic name). (a) Chemical...identified generically as aminofluoran derivative (PMN P-95-512) is subject...

2011-07-01

211

40 CFR 721.10172 - Alkylamide derivative (generic).  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Alkylamide derivative (generic). 721.10172 Section...Substances § 721.10172 Alkylamide derivative (generic). (a) Chemical substance...identified generically as alkylamide derivative (PMN P-03-633) is subject...

2012-07-01

212

40 CFR 721.9079 - Dihydro quinacridone derivative (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Dihydro quinacridone derivative (generic). 721.9079 Section... § 721.9079 Dihydro quinacridone derivative (generic). (a) Chemical substance...identified generically as dihydro quinacridone derivative (PMN P-01-397) is subject...

2011-07-01

213

40 CFR 721.10330 - Pyrazolone derivative (generic).  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Pyrazolone derivative (generic). 721.10330 Section...Substances § 721.10330 Pyrazolone derivative (generic). (a) Chemical substance...identified generically as pyrazolone derivative (PMN P-03-722) is subject...

2013-07-01

214

40 CFR 721.10317 - Alkyl phosphate derivative (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Alkyl phosphate derivative (generic). 721.10317 Section...Substances § 721.10317 Alkyl phosphate derivative (generic). (a) Chemical substance...identified generically as alkyl phosphate derivative (PMN P-02-1040) is subject...

2012-07-01

215

40 CFR 721.9079 - Dihydro quinacridone derivative (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Dihydro quinacridone derivative (generic). 721.9079 Section... § 721.9079 Dihydro quinacridone derivative (generic). (a) Chemical substance...identified generically as dihydro quinacridone derivative (PMN P-01-397) is subject...

2012-07-01

216

40 CFR 721.5925 - Bis heterocyclic phenylene derivative (generic).  

Code of Federal Regulations, 2012 CFR

... false Bis heterocyclic phenylene derivative (generic). 721.5925 Section...5925 Bis heterocyclic phenylene derivative (generic). (a) Chemical substance...generically as bis heterocyclic phenylene derivative (PMN P-01-0432) is subject...

2012-07-01

217

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2011 CFR

... Substituted phenylimino carbamate derivative. 721.2025 Section 721.2025... Substituted phenylimino carbamate derivative. (a) Chemical substance and significant...as a substituted phenylimino carbamate derivative (PMN P-91-487) is subject...

2011-07-01

218

40 CFR 721.646 - Aminofluoran derivative (generic name).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Aminofluoran derivative (generic name). 721.646 Section...Substances § 721.646 Aminofluoran derivative (generic name). (a) Chemical...identified generically as aminofluoran derivative (PMN P-95-512) is subject...

2012-07-01

219

40 CFR 721.1760 - Substituted benzotriazole derivatives.  

Code of Federal Regulations, 2010 CFR

... false Substituted benzotriazole derivatives. 721.1760 Section 721.1760...721.1760 Substituted benzotriazole derivatives. (a) Chemical substances and significant...generically as substituted benzotriazole derivatives (PMNs P-93-374 and...

2010-07-01

220

40 CFR 721.1760 - Substituted benzotriazole derivatives.  

Code of Federal Regulations, 2011 CFR

... false Substituted benzotriazole derivatives. 721.1760 Section 721.1760...721.1760 Substituted benzotriazole derivatives. (a) Chemical substances and significant...generically as substituted benzotriazole derivatives (PMNs P-93-374 and...

2011-07-01

221

40 CFR 721.9079 - Dihydro quinacridone derivative (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Dihydro quinacridone derivative (generic). 721.9079 Section... § 721.9079 Dihydro quinacridone derivative (generic). (a) Chemical substance...identified generically as dihydro quinacridone derivative (PMN P-01-397) is subject...

2013-07-01

222

40 CFR 721.5925 - Bis heterocyclic phenylene derivative (generic).  

Code of Federal Regulations, 2013 CFR

... false Bis heterocyclic phenylene derivative (generic). 721.5925 Section...5925 Bis heterocyclic phenylene derivative (generic). (a) Chemical substance...generically as bis heterocyclic phenylene derivative (PMN P-01-0432) is subject...

2013-07-01

223

40 CFR 721.10368 - Triphenodioxazine derivatives (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Triphenodioxazine derivatives (generic). 721.10368 Section... § 721.10368 Triphenodioxazine derivatives (generic). (a) Chemical substance...identified generically as triphenodioxazine derivatives (PMN P-10-84) is subject...

2012-07-01

224

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2012 CFR

... Substituted phenylimino carbamate derivative. 721.2025 Section 721.2025... Substituted phenylimino carbamate derivative. (a) Chemical substance and significant...as a substituted phenylimino carbamate derivative (PMN P-91-487) is subject...

2012-07-01

225

40 CFR 721.646 - Aminofluoran derivative (generic name).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Aminofluoran derivative (generic name). 721.646 Section...Substances § 721.646 Aminofluoran derivative (generic name). (a) Chemical...identified generically as aminofluoran derivative (PMN P-95-512) is subject...

2013-07-01

226

40 CFR 721.10172 - Alkylamide derivative (generic).  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Alkylamide derivative (generic). 721.10172 Section...Substances § 721.10172 Alkylamide derivative (generic). (a) Chemical substance...identified generically as alkylamide derivative (PMN P-03-633) is subject...

2013-07-01

227

40 CFR 721.10324 - Thionocarbamate derivative (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Thionocarbamate derivative (generic). 721.10324 Section...Substances § 721.10324 Thionocarbamate derivative (generic). (a) Chemical substance...identified generically as thionocarbamate derivative (PMN P-03-362) is subject...

2013-07-01

228

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2013 CFR

... Substituted phenylimino carbamate derivative. 721.2025 Section 721.2025... Substituted phenylimino carbamate derivative. (a) Chemical substance and significant...as a substituted phenylimino carbamate derivative (PMN P-91-487) is subject...

2013-07-01

229

40 CFR 721.5925 - Bis heterocyclic phenylene derivative (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Bis heterocyclic phenylene derivative (generic...Chemical Substances § 721.5925 Bis heterocyclic phenylene derivative (generic...substance identified generically as bis heterocyclic phenylene derivative (PMN...

2010-07-01

230

40 CFR 721.5925 - Bis heterocyclic phenylene derivative (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Bis heterocyclic phenylene derivative (generic...Chemical Substances § 721.5925 Bis heterocyclic phenylene derivative (generic...substance identified generically as bis heterocyclic phenylene derivative (PMN...

2011-07-01

231

Chemical Mechanical Planarization- Chemical  

NSDL National Science Digital Library

This website includes an animation which illustrates the chemical action of slurry in the chemical-mechanical planarization process. Objective: Explain the mechanical and chemical steps in the CMP process. This simulation is from Module 068 of the Process & Equipment III Cluster of the MATEC Module Library (MML). Find this animation under the section "Process & Equipment III." To view other clusters or for more information about the MML visit http://matec.org/ps/library3/process_I.shtmlKey Phrase: MATEC Animation

2012-12-07

232

Semisynthetic Derivatives of Epothilones  

NASA Astrophysics Data System (ADS)

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.

Altmann, Karl-Heinz

233

Nile Blue derivatives as lysosomotropic photosensitizers  

Microsoft Academic Search

The benzophenoxazines, including several Nile blue analogues, are a unique group of dyes that localize selectively in animal tumors. Chemical modifications of Nile blue A can yield derivatives with high 1O2 quantum yields. These derivatives represent a group of potentially effective photosensitizers for selective phototherapy of malignant tumors. In vitro evaluation of these derivatives has indicated that those with high

Chi-Wei Lin; Janine R. Shulok; S. D. Kirley; Louis Cincotta; James W. Foley

1991-01-01

234

LLNL Chemical Kinetics Modeling Group  

SciTech Connect

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.

Pitz, W J; Westbrook, C K; Mehl, M; Herbinet, O; Curran, H J; Silke, E J

2008-09-24

235

An Elementary Discussion of Chemical Equilibrium.  

ERIC Educational Resources Information Center

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)

David, Carl W.

1988-01-01

236

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...

237

Fractional Derivative as Fractional Power of Derivative  

E-print Network

Definitions of fractional derivatives as fractional powers of derivative operators are suggested. The Taylor series and Fourier series are used to define fractional power of self-adjoint derivative operator. The Fourier integrals and Weyl quantization procedure are applied to derive the definition of fractional derivative operator. Fractional generalization of concept of stability is considered.

Vasily E. Tarasov

2007-11-16

238

Identification of alkylphosphonic acid derivatives by IR and mass spectrometry  

Microsoft Academic Search

An approach is considered to the problem of identification of alkylphosphonic acid derivatives within Chemical Weapons Convention.\\u000a The technique is based on correlations between the structural fragments of toxic chemicals and their IR and mass spectra.

A. F. Kireev; I. V. Rybal’chenko; V. N. Suvorkin; V. I. Kholstov

2000-01-01

239

Chemical deposition of conducting polymers  

Microsoft Academic Search

The coating of different materials with conducting electroactive polymers (CEP), i.e. polyaniline, polypyrrole, polythiophene, and their derivatives, provided by means of chemical polymerization, is briefly reviewed. The topics covered include the deposition of CEP (i) by bulk oxidative chemical polymerization, (ii) by surface-located polymerization, and (iii) by coating of micro- and nanoparticles. The coating of different materials like polymers, polymer

A. Malinauskas

2001-01-01

240

Chemical Communication  

NSDL National Science Digital Library

A concise lesson about chemical communication in insects covering both semio and info chemicals. The site includes a short video of grape root borer moths using sex pheromone. Further links on the take the user to visual and auditory communication.

0002-11-30

241

Home Chemicals  

NSDL National Science Digital Library

This lesson provides an introduction to the occurrence and possible risks of household chemical products. Topics include some basic chemistry (how elements combine to form compounds), how chemicals are classified, and the idea of natural, as opposed to synthetic, chemicals. The lesson includes an activity in which students take an inventory of chemical products in their homes and research the possible hazards of some of them using an online resource developed by the National Institutes of Health (NIH).

Fox, Chris

242

Chemical sensor  

NASA Technical Reports Server (NTRS)

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.

Rauh, R. David (Inventor)

1990-01-01

243

Chemical microsensors  

NASA Astrophysics Data System (ADS)

Recent developments are discussed in the field of chemical microsensors that attempt to marry physical transducers based on microelectronic and optoelectronic technologies with thin films and coatings that serve as chemical transducers. Microelectronic silicon chemical sensors, acoustic wave sensors, microsensors based on optical fibers, and electrochemical microsensors are considered. Both technological achievements and problems that remain to be solved are addressed.

Hughes, R. C.; Ricco, A. J.; Butler, M. A.; Martin, S. J.

1991-10-01

244

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)

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

Allen, Mark Ryan

245

[Lactic acidosis and acute abdomen from biguanide intoxication].  

PubMed

Metformin, an anti-hyperglycaemic drug, reduces mortality in obese patients with a non-insulin-dependent diabetes mellitus type II (United Kingdom Prospective Diabetes Study) and is therefore recommended as the first line therapy. A metformin-associated lactic acidosis due to accumulation or intoxication is a rare but severe complication with a mortality rate of up to 50%. The main clinical symptoms are unspecific and the patient may present with acute abdominal pain and reduced consciousness. This can easily be misinterpreted and may lead to a wrong diagnosis. Only a thorough clinical examination and exact analysis of laboratory values in combination with the medical history and chronic medication will allow a correct diagnosis. We report a case of a 79-year-old female patient whose clinical symptoms were initially interpreted as an acute intestinal ischemia. A progressively deteriorating haemodynamic state led to an exploratory laparotomy. Postoperatively, the correct diagnosis of a metformin-associated lactic acidosis due to acute renal failure was made. In the course of the ICU stay the condition improved after bicarbonate haemodialysis and the patient was discharged 11 days after admission. PMID:14991192

Moerer, O; Barwing, J; Neumann, P

2004-02-01

246

Chemical Aspects of Organotin Derivatives of Beta?diketones, Quinonoids, Steroids and Some Currently Used Drugs: A Review of the Literature with Emphasis on the Medicinal Potential of Organotins  

Microsoft Academic Search

The last 50–70 years there has been an increasing interest on organotin compounds mainly because of their industrial, agricultural and biological applications. This review aims to offer a substantial overview of the organotin complexes of beta?diketones and beta?diketone derivatives, quinonoids, steroids and NSAIDs describing their structure, coordination mode and properties. Discussion will be focused on the interaction of organotins with

Vasiliki Valla

2007-01-01

247

[Chemical weapons and chemical terrorism].  

PubMed

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

Nakamura, Katsumi

2005-10-01

248

40 CFR 721.3560 - Derivative of tetra-chloro-ethy-lene.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Derivative of tetra-chloro-ethy-lene. ...Chemical Substances § 721.3560 Derivative of tetra-chloro-ethy-lene. ...paragraph (a)(2) of this section: Derivative of tetrachloroethylene,...

2013-07-01

249

40 CFR 721.3560 - Derivative of tetra-chloro-ethy-lene.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Derivative of tetra-chloro-ethy-lene. ...Chemical Substances § 721.3560 Derivative of tetra-chloro-ethy-lene. ...paragraph (a)(2) of this section: Derivative of tetrachloroethylene,...

2012-07-01

250

40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.  

Code of Federal Regulations, 2010 CFR

... false Oxo-substituted amino-al-kanoic acid derivative. 721.430...430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical...generically as oxo-substituted amino al-kan-oic acid derivative (PMN No....

2010-07-01

251

Drug laws and the 'derivative' problem.  

PubMed

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

King, Leslie A; Ujváry, István; Brandt, Simon D

2014-01-01

252

Design, chemical synthesis of 3-(9H-fluoren-9-yl)pyrrolidine-2,5-dione derivatives and biological activity against enoyl-ACP reductase (InhA) and Mycobacterium tuberculosis.  

PubMed

We report here the discovery, synthesis and screening results of a series of 3-(9H-fluoren-9-yl)pyrrolidine-2,5-dione derivatives as a novel class of potent inhibitors of Mycobacterium tuberculosis H37Rv strain as well as the enoyl acyl carrier protein reductase (ENR) InhA. Among them, several compounds displayed good activities against InhA which is one of the key enzymes involved in the type II fatty acid biosynthesis pathway of the mycobacteria cell wall. Furthermore, some exhibited promising activities against M. tuberculosis and multi-drug resistant M. tuberculosis strains. PMID:24140915

Matviiuk, Tetiana; Rodriguez, Frédéric; Saffon, Nathalie; Mallet-Ladeira, Sonia; Gorichko, Marian; de Jesus Lopes Ribeiro, Ana Luisa; Pasca, Maria Rosalia; Lherbet, Christian; Voitenko, Zoia; Baltas, Michel

2013-01-01

253

How accurate are the nonlinear chemical Fokker-Planck and chemical Langevin equations?  

Microsoft Academic Search

The chemical Fokker-Planck equation and the corresponding chemical Langevin equation are commonly used approximations of the chemical master equation. These equations are derived from an uncontrolled, second-order truncation of the Kramers-Moyal expansion of the chemical master equation and hence their accuracy remains to be clarified. We use the system-size expansion to show that chemical Fokker-Planck estimates of the mean concentrations

Ramon Grima; Philipp Thomas; Arthur V. Straube

2011-01-01

254

Chemical Reactions  

NSDL National Science Digital Library

We don't often stop to think about it, but underlying many of our everyday activities are chemical reactions. From the cooking of an egg to the growth of a child, chemical reactions make things happen. Although many of the reactions that support our lives

National Science Teachers Association (NSTA)

2009-05-01

255

Chemical sensors  

DOEpatents

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.

Lowell, Jr., James R. (Bend, OR); Edlund, David J. (Bend, OR); Friesen, Dwayne T. (Bend, OR); Rayfield, George W. (Bend, OR)

1991-01-01

256

Chemical sensors  

DOEpatents

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.

Lowell, J.R. Jr.; Edlund, D.J.; Friesen, D.T.; Rayfield, G.W.

1991-07-02

257

Chemical peels.  

PubMed

Chemical peels are a method of resurfacing with a long-standing history of safety in the treatment of various skin conditions. This article reviews the classification of different chemical agents based on their depth of injury. The level of injury facilitates cell turnover, epidermal thickening, skin lightening, and new collagen formation. Preprocedural, periprocedural, and postprocedural skin care are briefly discussed. To select the appropriate chemical peel, the provider should evaluate the patient's expectations, medical history, skin type, and possible complications to determine the best chemical peel to achieve the desired results. Patients with Fitzpatrick skin types IV to VI have increased risk of dyspigmentation, hypertrophic, and keloid scarring. These individuals respond well to superficial and medium-depth chemical peels. Advances in the use of combination peels allow greater options for skin rejuvenation with less risk of complications. PMID:24488634

Jackson, Adrianna

2014-02-01

258

Chemical threats.  

PubMed

The use of chemical agents as military weapons has been recognized for many centuries but reached the most feared and publicized level during World War I. Considerable political effort has been exercised in the twentieth century to restrict military strategies with chemicals. However, considerable concern currently exists that chemical weapons may be used as agents in civilian terrorism. The distribution of acetaminophen tablets contaminated with potassium cyanide and the release of sarin in the Tokyo sub-way system show that larger-scale deployment of chemical agents can be a reality. This reality makes it necessary for civilian disaster-planning strategies to incorporate an understanding of chemical agents, their effects, and the necessary treatment. PMID:16781273

Fry, Donald E

2006-06-01

259

Structural, ferroelectric, dielectric, and magnetic properties of BiFeO3/Pb(Zr0.5,Ti0.5)O3 multilayer films derived by chemical solution deposition  

NASA Astrophysics Data System (ADS)

BiFeO3/Pb(Zr0.5,Ti0.5)O3 (BFO/PZT) multilayer films have been grown on platinum-coated silicon substrate by chemical solution deposition. The remnant polarization is about 12?C /cm2, which is much bigger than most of pure BFO thin films. P-E measurement shows that there are more obstacles affecting the motion of the domain wall in the multilayer films than those in the pure PZT films. This conclusion is also confirmed by measuring the dependence of capacitance with ac field under subswitching field. The frequency dependence of dielectric loss indicates that the dielectric loss (tan? ) of the multilayer is smaller than that of the PZT thin films at high frequency. Magnetic measurement indicates that the multilayer films are antiferromagnetic.

Li, Y. W.; Sun, J. L.; Chen, J.; Meng, X. J.; Chu, J. H.

2005-10-01

260

Protein Chemical Shift Prediction  

E-print Network

The protein chemical shifts holds a large amount of information about the 3-dimensional structure of the protein. A number of chemical shift predictors based on the relationship between structures resolved with X-ray crystallography and the corresponding experimental chemical shifts have been developed. These empirical predictors are very accurate on X-ray structures but tends to be insensitive to small structural changes. To overcome this limitation it has been suggested to make chemical shift predictors based on quantum mechanical(QM) calculations. In this thesis the development of the QM derived chemical shift predictor Procs14 is presented. Procs14 is based on 2.35 million density functional theory(DFT) calculations on tripeptides and contains corrections for hydrogen bonding, ring current and the effect of the previous and following residue. Procs14 is capable at performing predictions for the 13CA, 13CB, 13CO, 15NH, 1HN and 1HA backbone atoms. In order to benchmark Procs14, a number of QM NMR calculatio...

Larsen, Anders S

2014-01-01

261

40 CFR 721.6097 - Phosphoric acid derivative (generic name).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Phosphoric acid derivative (generic name). 721.6097 Section...Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical...identified generically as a phosphoric acid derivative (PMN P-95-284) is subject...

2010-07-01

262

40 CFR 721.6097 - Phosphoric acid derivative (generic name).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Phosphoric acid derivative (generic name). 721.6097 Section...Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical...identified generically as a phosphoric acid derivative (PMN P-95-284) is subject...

2013-07-01

263

40 CFR 721.6097 - Phosphoric acid derivative (generic name).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Phosphoric acid derivative (generic name). 721.6097 Section...Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical...identified generically as a phosphoric acid derivative (PMN P-95-284) is subject...

2011-07-01

264

40 CFR 721.6097 - Phosphoric acid derivative (generic name).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Phosphoric acid derivative (generic name). 721.6097 Section...Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical...identified generically as a phosphoric acid derivative (PMN P-95-284) is subject...

2012-07-01

265

Unnecessary Chemicals  

ERIC Educational Resources Information Center

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)

Johnson, Anita

1978-01-01

266

Chemical Analyses.  

National Technical Information Service (NTIS)

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 tetra...

J. W. Bulluck, R. A. Rushing

1994-01-01

267

Chemical sensors  

DOEpatents

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.

Lowell, Jr., James R. (Bend, OR); Edlund, David J. (Bend, OR); Friesen, Dwayne T. (Bend, OR); Rayfield, George W. (Eugene, OR)

1992-01-01

268

Chemical sensors  

DOEpatents

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.

Lowell, J.R. Jr.; Edlund, D.J.; Friesen, D.T.; Rayfield, G.W.

1992-06-09

269

Automated large-scale culture and medium-throughput chemical screen for modulators of proliferation and viability of human induced pluripotent stem cell-derived neuroepithelial-like stem cells.  

PubMed

The aim of this study was to demonstrate proof-of-concept feasibility for the use of human neural stem cells (NSCs) for high-throughput screening (HTS) applications. For this study, an adherent human induced pluripotent stem (iPS) cell-derived long-term, self-renewing, neuroepithelial-like stem (lt-NES) cell line was selected as a representative NSC. Here, we describe the automated large-scale serum-free culture ("scale-up") of human lt-NES cells on the CompacT SelecT cell culture robotic platform, followed by their subsequent automated "scale-out" into a microwell plate format. We also report a medium-throughput screen of 1000 compounds to identify modulators of neural stem cell proliferation and/or survival. The screen was performed on two independent occasions using a cell viability assay with end-point reading resulting in the identification of 24 potential hit compounds, 5 of which were found to increase the proliferation and/or survival of human lt-NES on both occasions. Follow-up studies confirmed a dose-dependent effect of one of the hit compounds, which was a Cdk-2 modulator. This approach could be further developed as part of a strategy to screen compounds to either improve the procedures for the in vitro expansion of neural stem cells or to potentially modulate endogenous neural stem cell behavior in the diseased nervous system. PMID:23042076

McLaren, Donna; Gorba, Thorsten; Marguerie de Rotrou, Anita; Pillai, Gopalan; Chappell, Clare; Stacey, Alison; Lingard, Sarah; Falk, Anna; Smith, Austin; Koch, Philipp; Brüstle, Oliver; Vickers, Richard; Tinsley, Jon; Flanders, David; Bello, Paul; Craig, Stewart

2013-03-01

270

Chelate derivatives as protectors against tissue injury  

US Patent & Trademark Office Database

Derivatives useful in the protection of living organisms against damage due to free radical reactions derived from methoxypolyethylene glycols (MPEG), which are modified by chemically attaching chelating groups in an amide or amine linkage to the nonmethyl end of the polymer. Such chelating groups include ethylene-diamine tetraacetic acid (EDTA), diethylene triamine pentaacetic acid (DTPA), and ethylene glycol aminoethyl ether tetraacetic acid (EGTA), and pharmacologically acceptable salts or esters thereof.

2000-02-01

271

Defense against chemical warfare agents and toxic industrial chemicals  

Microsoft Academic Search

Research on mitigation of toxic threats is critical to national defense, but is often hazardous. Toxicity generally arises at the molecular level via reactions between toxins and host biomolecules. This lends itself well to simulations from which one may safely derive the insight required for effective preventative or therapeutic response strategies. Thus, we have applied quantum chemical methods to address

Margaret M. Hurley; J. B. Wright; A. Balboa; G. H. Lushington

2003-01-01

272

Chemical sensors  

SciTech Connect

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.

Hubbard, C.W.; Gordon, R.L.

1987-05-01

273

Chemical Modification of Polysaccharides  

PubMed Central

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

Cumpstey, Ian

2013-01-01

274

New dextran derivatives. I. Nitrogen containing derivatives.  

PubMed

Three new derivatives of dextran were obtained: 3-morpholine-2-hydroxypropyl ether of dextran (I), hydroxamic acid of carboxymethyl dextran (II), and oxime of ketodextran (III). All the three derivatives exhibited low toxicity at parenteral administration to laboratory animals. (I) and (II) showed the capability of weakening the activity of tetanus and malignant edema toxins. Additionally, (I) showed immunotropic activity. Biological activity was observed when the derivative (I) had been obtained from dextran of the molecular weight 4000. At the molecular weight 20,000 the activity did not appear. Similarly, no activity was observed under oral administration. PMID:6202271

Mioduszewski, J Z; Halski, L; Mioduszewska, M

1983-01-01

275

Chemical Mahjong  

ERIC Educational Resources Information Center

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…

Cossairt, Travis J.; Grubbs, W. Tandy

2011-01-01

276

Delicious Chemicals.  

ERIC Educational Resources Information Center

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…

Barry, Dana M.

277

Chemical Wonders  

NSDL National Science Digital Library

Students are introduced to chemical engineering and learn about its many different applications. They are provided with a basic introduction to matter and its different properties and states. An associated hands-on activity gives students a chance to test their knowledge of the states of matter and how to make observations using their five senses: touch, smell, sound, sight and taste.

Integrated Teaching And Learning Program

278

Chemical Changes  

NSDL National Science Digital Library

This is an excellent resource for teachers and students. It offers countless lab ideas for teaching chemical and physical changes and is geared for fifth through eighth grade. It also gives interactive web addresses for students and includes PowerPoint presentations on this topic.

can't tell- a science educator- not affiliated with any specific organization

2011-10-10

279

Biofuels and bio-products derived from  

E-print Network

NEED Biofuels and bio- products derived from lignocellulosic biomass (plant materials) are part improve the energy and carbon efficiencies of biofuels production from a barrel of biomass using chemical and thermal catalytic mechanisms. The Center for Direct Catalytic Conversion of Biomass to Biofuels IMPACT

Ginzel, Matthew

280

40 CFR 721.1300 - [(Dinitrophenyl)azo]-[2,4-dia-mino-5-methoxybenzene] derivatives.  

Code of Federal Regulations, 2011 CFR

...4-dia-mino-5-methoxybenzene] derivatives. 721.1300 Section 721.1300...4-dia-mino-5-methoxybenzene] derivatives. (a) Chemical substances and significant...4-di-a-mino-5-methoxybenzene] derivatives (P-83-817 and...

2011-07-01

281

40 CFR 721.7620 - Alkyl(heterocyclicyl) phe-nyl-azohetero monocyclic polyone, ((alkylimidazolyl) methyl) derivative...  

Code of Federal Regulations, 2013 CFR

...polyone, ((alkylimidazolyl) methyl) derivative (generic name). 721.7620 Section...polyone, ((alkylimidazolyl) methyl) derivative (generic name). (a) Chemical...al-kyli-mi-da-zolyl) methyl) derivative (PMN P-86-136) is subject...

2013-07-01

282

40 CFR 721.7620 - Alkyl(heterocyclicyl) phe-nyl-azohetero monocyclic polyone, ((alkylimidazolyl) methyl) derivative...  

Code of Federal Regulations, 2010 CFR

...polyone, ((alkylimidazolyl) methyl) derivative (generic name). 721.7620 Section...polyone, ((alkylimidazolyl) methyl) derivative (generic name). (a) Chemical...al-kyli-mi-da-zolyl) methyl) derivative (PMN P-86-136) is subject...

2010-07-01

283

40 CFR 721.1300 - [(Dinitrophenyl)azo]-[2,4-dia-mino-5-methoxybenzene] derivatives.  

Code of Federal Regulations, 2012 CFR

...4-dia-mino-5-methoxybenzene] derivatives. 721.1300 Section 721.1300...4-dia-mino-5-methoxybenzene] derivatives. (a) Chemical substances and significant...4-di-a-mino-5-methoxybenzene] derivatives (P-83-817 and...

2012-07-01

284

40 CFR 721.7620 - Alkyl(heterocyclicyl) phe-nyl-azohetero monocyclic polyone, ((alkylimidazolyl) methyl) derivative...  

Code of Federal Regulations, 2011 CFR

...polyone, ((alkylimidazolyl) methyl) derivative (generic name). 721.7620 Section...polyone, ((alkylimidazolyl) methyl) derivative (generic name). (a) Chemical...al-kyli-mi-da-zolyl) methyl) derivative (PMN P-86-136) is subject...

2011-07-01

285

40 CFR 721.1300 - [(Dinitrophenyl)azo]-[2,4-dia-mino-5-methoxybenzene] derivatives.  

Code of Federal Regulations, 2010 CFR

...4-dia-mino-5-methoxybenzene] derivatives. 721.1300 Section 721.1300...4-dia-mino-5-methoxybenzene] derivatives. (a) Chemical substances and significant...4-di-a-mino-5-methoxybenzene] derivatives (P-83-817 and...

2010-07-01

286

40 CFR 721.1300 - [(Dinitrophenyl)azo]-[2,4-dia-mino-5-methoxybenzene] derivatives.  

Code of Federal Regulations, 2013 CFR

...4-dia-mino-5-methoxybenzene] derivatives. 721.1300 Section 721.1300...4-dia-mino-5-methoxybenzene] derivatives. (a) Chemical substances and significant...4-di-a-mino-5-methoxybenzene] derivatives (P-83-817 and...

2013-07-01

287

Chemical peel.  

PubMed

Chemical face peeling as described in this article produces gross and microscopic changes in the skin which are permanent. The most important aspect in assuring the success of this procedure is the proper selection of patients. The primary use of this procedure is for the purpose of eliminating wrinkles, whether as the primary or ancillary procedure, such as regional peeling. Chemical peeling of the face is a valuable adjunct in the treatment of the aging face and can produce some rather dramatic results with the careful selection of patients and meticulous attention to detail in carrying out the peel, as well as the exact adherence to the post peel instructions by the patient. PMID:639446

Mosienko, P; Baker, T J

1978-01-01

288

Chemical warfare  

PubMed Central

Leaf-cutting ants are well known for their highly complex social organization, which provides them with a strong defense against parasites invading their colonies. Besides this attribute, these insects have morphological, physiological and structural characteristics further reinforcing the defense of their colonies. With the discovery of symbiotic bacteria present on the integument of leaf-cutting ants, a new line of defense was proposed and considered to be specific for the control of a specialized fungal parasite of the ants’ fungus gardens (Escovopsis). However, recent studies have questioned the specificity of the integumental bacteria, as they were also found to inhibit a range of fungi, including entomopathogens. The microbiota associated with the leaf-cutting ant gardens has also been proposed as another level of chemical defense, protecting the garden from parasite invasion. Here we review the chemical defense weaponry deployed by leaf-cutting ants against parasites of their fungus gardens and of the ants themselves. PMID:23795235

Samuels, Richard Ian; Mattoso, Thalles Cardoso; Moreira, Denise D.O.

2013-01-01

289

Chemical Reactions  

NSDL National Science Digital Library

We are going go over a general view of reactions to prepare us for our unit on Chemical Reactions! Have fun learning! WARNING: If you are caught looking at ANY other site, without permission, you will be sent to the ALC, and you will not participate in any other computer activities for the rest of the year. Get your worksheet and begin! Overview Take this quiz and have me come over and sign off on your worksheet when you have completed the quiz! Overview Quiz Next let's take a look at what effect the rate of a chemical reaction. Rates of Reactions Another quiz, another check off by me! Rates of Reactions Quiz Now how do we measure how fast a ...

Hicken, Mrs.

2009-05-04

290

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 ...

291

The mutagenicities of seven coumarin derivatives and a furan derivative (nimbolide) isolated from three medicinal plants  

Microsoft Academic Search

Seven coumarin derivatives (imperatorin, heraclenin, xanthotoxin, marmesin, chelepin, oxypeucedanin, esculin) and a furan derivative (nimbolide) were screened on 6 Ames tester strains (TA92, TA94, TA97, TA98, TA100, TA102). The eight compounds are chemicals isolated from three Nigerian medicinal plants: Afraegle paniculata, Clausena anisata, and Azadirachta indica. Different preparations of the former are taken by Nigerians for gut disturbances, and a

Anthony O. Uwaifo

1984-01-01

292

Chemical lasers  

NASA Astrophysics Data System (ADS)

The application and the advances of quantum electronics, specifically, of optical quantum generators lasers is reviewed. Materials are cut, their surfaces are machined, chemical transformations of substances are carried out, surgical operations are performed, data are transmitted, three dimensional images are produced and the content of microimpurities, in the atmosphere, are analyzed by use of a beam. Laser technology is used in conducting investigations in the most diverse fields of the natural and technical sciences from controlled thermonuclear fusion to genetics. Many demands are placed on lasers as sources of light energy. The importance of low weight, compactness of the optical generator and the efficiency of energy conversion processes is emphasized.

Khariton, Y.

1984-08-01

293

Chemical Separations  

NSDL National Science Digital Library

This site contains complete notes in a PowerPoint-like presentation for a chemical separations course. It covers a wide variety of topics, including distillation, extraction, gas chromatography, liquid chromatograpy, chromatography theory, instrumentation, electrophoresis, field flow fractionation, and affinity chromatography. It covers these topics thoroughly using a clear, consistent, and simple presentation style. Links to major topics like GC, LC, and electrophoresis provide specific information about the theory, instrumentation, and practice related to these techniques. The site also contains many annimations illustrating important separation processes.

2011-05-18

294

Microbial chemical factories: recent advances in pathway engineering for synthesis of value added chemicals  

E-print Network

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 ...

Dhamankar, Himanshu Hemant

295

Pyrazine-Derived Disulfide-Reducing Agent for Chemical Biology  

PubMed Central

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

Lukesh, John C.; Wallin, Kelly K.

2014-01-01

296

Partial Derivatives: Geometric Visualization  

NSDL National Science Digital Library

This write-pair-share activity presents Calculus III students with a worksheet containing several exercises that require them to find partial derivatives of functions of two variables. Afterwards, a series of Web-based animations are used to illustrate the surface of each function, the path of the indicated partial derivative for a specified value of the variable and the value of the derivative at each point along the path.

Rutledge, James

297

Nearly generalized Jordan derivations  

E-print Network

Let $A$ be an algebra and let $X$ be an $A$-bimodule. A $\\Bbb C-$linear mapping $d:A \\to X$ is called a generalized Jordan derivation if there exists a Jordan derivation (in the usual sense) $\\delta:A \\to X$ such that $d(a^2)=ad(a)+\\delta(a)a$ for all $a \\in A.$ The main purpose of this paper to prove the Hyers-Ulam-Rassias stability and superstability of the generalized Jordan derivations.

Gordji, M Eshaghi

2008-01-01

298

Endohedral Metallofullerene Derivatives  

NASA Technical Reports Server (NTRS)

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.

Dorn, Harry C. (Inventor); Iezzi, Erick B. (Inventor); Duchamp, James (Inventor)

2008-01-01

299

Photosynthetic approaches to chemical biotechnology.  

PubMed

National interest and environmental advocates encourage alternatives to petroleum-based products. Besides biofuels, many other valuable chemicals used in every-day life are petroleum derivatives or require petroleum for their production. A plausible alternative to production using petroleum for chemical production is to harvest the abundant carbon dioxide resources in the environment to produce valuable hydrocarbons. Currently, efforts are being made to utilize a natural biological system, photosynthetic microorganisms, to perform this task. Photosynthetic microorganisms are attractive to use for biochemical production because they utilize economical resources for survival: sunlight and carbon dioxide. This review examines the various compounds produced by photosynthetic microorganisms. PMID:23578466

Desai, Shuchi H; Atsumi, Shota

2013-12-01

300

21 CFR 189.120 - Cobaltous salts and its derivatives.  

...2014-04-01 2014-04-01 false Cobaltous salts and its derivatives. 189.120 Section 189.120 Food and Drugs FOOD...Use as Human Food § 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4 H6...

2014-04-01

301

The derivative of a function of one variable Partial derivatives  

E-print Network

The derivative of a function of one variable Partial derivatives Partial differential equations Partial Differential Equations Introduction Partial Differential Equations #12;The derivative of a function of one variable Partial derivatives Partial differential equations Review Check your understanding

Lega, Joceline

302

Chemical Analyses  

NASA Technical Reports Server (NTRS)

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.

Bulluck, J. W.; Rushing, R. A.

1994-01-01

303

Partial Derivative Visualization Gallery  

NSDL National Science Digital Library

This resource is a small gallery of demos for illustrating partial derivatives geometrically. These animations can be used by instructors in a classroom setting or by students to aid in acquiring a visualization background for partial derivatives. Two file formats, gif and QuickTime files are used for the animations which can be downloaded.

Roberts, Lila F.; Hill, David R.

2004-11-11

304

Irregularities in Imperfective Derivation  

ERIC Educational Resources Information Center

This article discusses presentation of Russian conjugation via the one-stem system advocated by Lipson and Townsend, and attempts a more unified and complete presentation of irregularities in imperfect derivation. Two major irregularities are occurrence of an unexpected suffix and unpredictable alternation in the root of the derived imperfective.…

Levin, Maurice I.

1977-01-01

305

Carbon Nano Tube Composites with Chemically Functionalized Plant Oils  

Microsoft Academic Search

Carbon Nano Tube Composites with Chemically Functionalized Plant Oil Wim Thielemans, R., P. Wool, V. Barron and W. Blau Multi-Wall Carbon Nano Tubes (MWCNT) made by the Kratchmer-Huffman CCVD process were found to interact and solubilize by slow mechanical stirring, with chemically functionalized plant oils, such as acrylated, epoxidized and maleinated triglycerides (TG) derived from plant oils. The chemical functionality

Wim Thielemans; Richard P. Wool; Werner Blau; Valerie Barron

2003-01-01

306

Chemical Accelerators The phrase "chemical accelerators"  

E-print Network

Meetings Chemical Accelerators The phrase "chemical accelerators" is scarcely older than for one or two dozen people grew to include nearly a hundred. Chemical accelerators is a name sug- gested by one of us for devices that produce beams of chemically interesting species at relative kinetic

Zare, Richard N.

307

Nature's chemicals and synthetic chemicals: Comparative toxicology  

Microsoft Academic Search

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

B. N. Ames; M. Profet; L. S. Gold

1990-01-01

308

The Partial Derivative Machine  

NSDL National Science Digital Library

Research has shown that students struggle to understand the use of partial derivatives in thermodynamics. We have designed an apparatus, which we have called a Partial Derivative Machine, that serves as a mechanical analogue of a thermodynamic system. Using this device, students have a tangible way to wrestle with issues related to partial derivatives and thermodynamics, such as which variables are held fixed, how many variables are independent, and how energy can be added to a system. In this paper, we present a description of the apparatus, an introduction to the associated activities, and an overview of how this apparatus can be connected to thermodynamic systems.

Sherer, Grant; Kustusch, Mary B.; Manogue, Corinne A.; Roundy, David J.

2014-01-31

309

Chemical Evolution of the Galaxy  

E-print Network

Standard models for the chemical evolution of the Galaxy are reviewed with particular emphasis on the history of the abundance gradients in the disk. The effects on the disk structure and metallicity of gas accretion are discussed, showing that a significant fraction of the current disk mass has been accreted in the last Gyrs and that the chemical abundances of the infalling gas can be non primordial but should not exceed 0.3 Z(sun). The distributions with time and with galactocentric distance of chemical elements are discussed, comparing the observational data with the corresponding theoretical predictions by standard models, which reproduce very well the ISM abundances at various epochs, but not equally well all the features derived from observations of old stellar objects.

M. Tosi

1994-11-15

310

Rosmarinic acid derivatives from Salvia officinalis  

Microsoft Academic Search

Sagerinic acid, a novel cyclobutane and salvianolic acid K, derived from rosmarinic acid,were isolated together with the parent compound from polar solvent extracts of Salvia officinalis.Their chemical structures were elucidated by NMR and, for sagerinic acid, the stereochemistry ofthe substituents on the cyclobutane moiety was established as 3?,4a-diaryl-1a,2?-dicarboxylicacid diester (m-truxinate form).

Yinrong Lu; L. Yeap Foo

1999-01-01

311

Derivative Dispersion Relations  

E-print Network

We discuss some analytical and numerical aspects related to the replacement of integral dispersion relations by derivative relations and also the practical applicability of the derivative approach in the investigation of high-energy elastic hadron-hadron scattering. Making use of a Monopole Pomeron model and singly subtracted integral and derivative dispersion relations, we present the results of fits to the experimental data on the total cross sections and the ratio of the real to the imaginary part of the forward elastic scattering amplitude (proton-proton and antiproton-proton interactions). The emphasis is on the region of low energies and, in particular, we show that once the subtraction constant is used as a free fit parameter the derivative approach is equivalent to the integral approach even below the energy cutoff of the fitted data.

R. F. Avila; M. J. Menon

2004-11-30

312

Derivative Matching Game  

NSDL National Science Digital Library

Once again, the Mathematical Association of America has struck instructional gold with this latest gem from their online collection of resources for mathematics educators. Created by Barbara Margolius, this derivative matching game presents users with a game board showing graphs of functions on cards. Essentially, the goal of the game is to match the functions with their derivatives. Visitors can begin by reading an overview of the game, along with some brief instructions, and then they should dive right in. The game can also be customized to match functions with just first derivatives or both first and second derivatives. Mathematics educators will have a lot of fun with this one, and even the mathematically uncertain can be drawn into the fold with this easy to use resource.

2009-05-29

313

Derivative Matching Game  

NSDL National Science Digital Library

Once again, the Mathematical Association of America has struck instructional gold with this latest gem from their online collection of resources for mathematics educators. Created by Barbara Margolius, this derivative matching game presents users with a game board showing graphs of functions on cards. Essentially, the goal of the game is to match the functions with their derivatives. Visitors can begin by reading an overview of the game, along with some brief instructions, and then they should dive right in. The game can also be customized to match functions with just first derivatives or both first and second derivatives. Mathematics educators will have a lot of fun with this one, and even the mathematically uncertain can be drawn into the fold with this easy to use resource.

314

Credit derivatives in Brazil  

E-print Network

The amounts outstanding of credit derivatives have grown exponentially over the past years, and these financial intruments that allow market participants to trade credit risk have become very popular in Europe and in the ...

Rüther, Henrique

2007-01-01

315

Deriving Common Model Characteristics  

NSDL National Science Digital Library

In this activity, students confront several different models - from the DNA helix Watson and Crick constructed in their laboratory to a map of McDonalds density in the US - and work in small groups to derive their commonalities.

Momsen, Jennifer; Long, Tammy M.; Speth, Elena B.

316

Extended Derivative Dispersion Relations  

E-print Network

It is shown that, for a wide class of functions with physical interest as forward scattering amplitudes, integral dispersion relations can be replaced by derivative forms without any high-energy approximation. The applicability of these extended derivative relations, in the investigation of forward proton-proton and antiproton-proton elastic scattering, is exemplified by means of a Pomeron-Reggeon model with totally nondegenerate trajectories.

R. F. Avila; M. J. Menon

2006-01-24

317

Nearly generalized Jordan derivations  

Microsoft Academic Search

Let $A$ be an algebra and let $X$ be an $A$-bimodule. A $\\\\Bbb C-$linear mapping $d:A \\\\to X$ is called a generalized Jordan derivation if there exists a Jordan derivation (in the usual sense) $\\\\delta:A \\\\to X$ such that $d(a^2)=ad(a)+\\\\delta(a)a$ for all $a \\\\in A.$ The main purpose of this paper to prove the Hyers-Ulam-Rassias stability and superstability of the

M. Eshaghi Gordji; N. Ghobadipour

2008-01-01

318

Nearly generalized Jordan derivations  

Microsoft Academic Search

Let A be an algebra and let X be an A-bimodule. A ?-linear mapping d: A ? X is called a generalized Jordan derivation if there exists a Jordan derivation (in the usual sense) ?: A ? X such that d(a\\u000a 2) = ad(a)+?(a)a for all a ? A. The main purpose of this paper is to prove the Hyers-Ulam-Rassias

M. Eshaghi Gordji; N. Ghobadipour

2011-01-01

319

Renewable Chemicals: Dehydroxylation of Glycerol and Polyols  

PubMed Central

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

ten Dam, Jeroen; Hanefeld, Ulf

2011-01-01

320

Renewable chemicals: dehydroxylation of glycerol and polyols.  

PubMed

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

ten Dam, Jeroen; Hanefeld, Ulf

2011-08-22

321

Phytol derivatives as drug resistance reversal agents.  

PubMed

Phytol was chemically transformed into fifteen semi-synthetic derivatives, which were evaluated for their antibacterial and drug resistance reversal potential in combination with nalidixic acid against E.?coli strains CA8000 and DH5?. The pivaloyl (4), 3,4,5-trimethoxybenzoyl (9), 2,3-dichlorobenzoyl (10), cinnamoyl (11), and aldehyde (14) derivatives of phytol ((2E,7R,11R)-3,7,11,15-tetramethyl-2-hexadecen-1-ol) were evaluated by using another antibiotic, tetracycline, against the MDREC-KG4 clinical isolate of E.?coli. Derivative 4 decreased the maximal inhibitory concentration (MIC) of the antibiotics by 16-fold, while derivatives 9, 10, 11, and 14 reduced MIC values of the antibiotics up to eightfold against the E.?coli strains. Derivatives 4, 9, 10, 11, and 14 inhibited the ATP-dependent efflux pump; this was also supported by their in silico binding affinity and down-regulation of the efflux pump gene yojI, which encodes the multidrug ATP-binding cassette transporter protein. This study supports the possible use of phytol derivatives in the development of cost-effective antibacterial combinations. PMID:24891085

Upadhyay, Harish C; Dwivedi, Gaurav R; Roy, Sudeep; Sharma, Ashok; Darokar, Mahendra P; Srivastava, Santosh K

2014-08-01

322

Chemical Homogeneity in Collinder 261 and Implications for Chemical Tagging  

E-print Network

This paper presents abundances for 12 red giants of the old open cluster Collinder 261 based on spectra from VLT/UVES. Abundances were derived for Na, Mg, Si, Ca, Mn, Fe, Ni, Zr and Ba. We find the cluster has a solar-level metallicity of [Fe/H] = -0.03 dex. However some alpha elements were found to be enhanced. The star-to-star scatter was consistent with the expected measurement uncertainty for all elements. The observed rms scatter is as follows: Na = 0.07, Mg = 0.05, Si = 0.06, Ca = 0.05, Mn = 0.03, Fe = 0.02, Ni = 0.04, Zr = 0.12, and Ba = 0.03 dex. The intrinsic scatter was estimated to be less than 0.05 dex. Such high levels of homogeneity indicate that chemical information remains preserved in this old open cluster. We use the chemical homogeneity we have now established in Cr 261, Hyades and the HR1614 moving group to examine the uniqueness of the individual cluster abundance patterns, ie. chemical signatures. We demonstrate that the three studied clusters have unique chemical signatures, and discuss how other such signatures may be searched for in the future. Our findings support the prospect of chemically tagging disk stars to common formation sites in order to unravel the dissipative history of the Galactic disk.

G. M. De Silva; K. C. Freeman; M. Asplund; J. Bland-Hawthorn; M. S. Bessell; R. Collet

2006-11-28

323

Dielectric transition of polyacrylonitrile derived carbon nanofibers  

NASA Astrophysics Data System (ADS)

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.

Li, Jiangling; Su, Shi; Zhou, Lei; Abbot, Andrew M.; Ye, Haitao

2014-09-01

324

Exposure Levels for Chemical Threat Compounds; Information to Facilitate Chemical Incident Response  

SciTech Connect

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.

Hauschild, Veronique [U.S. Army Public Health Command] [U.S. Army Public Health Command; Watson, Annetta Paule [ORNL] [ORNL

2013-01-01

325

NMR spectra and structures of oridonin derivatives complexes with ?-cyclodextrin.  

PubMed

Complexations between three oridonin derivatives and ?-cyclodextrin (?CD) were studied by nuclear magnetic resonance (NMR) method. Job's plots for complexes were depicted by (1) H NMR spectra chemical shifts, which proved the 1:1 stoichiometry inclusion complex formation between each derivative and ?CD. Two-dimensional rotating frame overhauser effect spectroscopy (2D ROESY) support the above conclusion and also proved that ring A of each oridonin derivative deeply enters into hydrophobic cavity from the wider rim and the other parts are outside the cavity. Apparent formation constants (Ka ) of complexes between three oridonin derivatives and two CDs are calculated according to Scott's equation. Copyright © 2011 John Wiley & Sons, Ltd. PMID:21815208

Liu, Wei; Zhao, Bing; Li, Yin-Chao; Liu, Hong-Min

2011-09-01

326

Chemical evolution models for NGC 6822 using planetary nebulae abundances  

NASA Astrophysics Data System (ADS)

We present chemical evolution models for the dwarf irregular NGC 6822, using chemical abundances of Planetary Nebulae (PNe) and HII regions and also the mass of gas (M gas ) as observational constraints. Chemical evolution models have been calculated to reproduce the abundances as derived from both, collisionally excited lines (CELs) and recombination lines (RLs). In our models, the chemical contribution of low and intermediate mass stars (LIMS) is time delayed, while for the massive stars the chemical contribution is instantaneous, as in Franco & Carigi (2008). The chemical contribution of SNIa is included in our model, thus we are also able to reproduce the observational Fe/H abundance obtained from A stars.

Hernández-Martínez, Liliana; Carigi, Leticia; Peña, Miriam; Peimbert, Manuel

2012-08-01

327

Modern Chemical Technology, Guidebook for Chemical Technicians.  

ERIC Educational Resources Information Center

This volume is a part of the ACS "Modern Chemical Technology" (ChemTeC) curriculum that is developed for chemical technicians. It is intended as a handbook that will be used throughout the instruction. Safety is stressed in eight of the ten chapters under the headings: safety in the chemical laboratory, personal protective equipment, fire safety…

Pecsok, Robert L.; Chapman, Kenneth

328

Chemical and Biomolecular Engineering  

E-print Network

Chemical and Biomolecular Engineering Combining theory and neutron scattering to understand molecular diffusion in porous materials David Sholl School of Chemical & Biomolecular Engineering Georgia Institute of Technology #12;Chemical and Biomolecular Engineering Porous materials www

Pennycook, Steve

329

CHEMICALS IN PROGRESS BULLETIN  

EPA Science Inventory

Chemicals in Progress Bulletin is a quarterly newsletter which highlights regulatory and program activities of the Office of Pollution Prevention and Toxics. Regular features and news items include the existing chemicals program, new chemicals program, pollution prevention activi...

330

Microfluidic chemical reaction circuits  

DOEpatents

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.

Lee, Chung-cheng (Irvine, CA); Sui, Guodong (Los Angeles, CA); Elizarov, Arkadij (Valley Village, CA); Kolb, Hartmuth C. (Playa del Rey, CA); Huang, Jiang (San Jose, CA); Heath, James R. (South Pasadena, CA); Phelps, Michael E. (Los Angeles, CA); Quake, Stephen R. (Stanford, CA); Tseng, Hsian-rong (Los Angeles, CA); Wyatt, Paul (Tipperary, IE); Daridon, Antoine (Mont-Sur-Rolle, CH)

2012-06-26

331

Credit Derivatives and Risk Management.  

National Technical Information Service (NTIS)

The striking growth of credit derivatives suggests that market participants find them to be useful tools for risk management. I illustrate the value of credit derivatives with three examples. A commercial bank can use credit derivatives to manage the risk...

M. S. Gibson

2007-01-01

332

Protective Effects of Synthetic Hydroxytyrosol Acetyl Derivatives against Oxidative Stress in Human Cells  

Microsoft Academic Search

Chemically stable di- and triacetyl derivatives of the natural o-diphenol antioxidant hydroxytyrosol were synthesized, and their chemical and biological antioxidant activities were assessed in comparison with that of the native synthetic compound. The chemical antioxidant activity of the selected compounds was evaluated by measuring the ferric reducing antioxidant power (FRAP). The data clearly indicate that, as expected, the hydroxytyrosol analogues,

Caterina Manna; Valentina Migliardi; Filomena Sannino; Antonio De Martino; Renato Capasso

2005-01-01

333

Metal derivatives of tetrazoles  

NASA Astrophysics Data System (ADS)

Published data on the synthesis, structure, properties and applications of metal derivatives of tetrazoles are generalised and described systematically. Compounds based on the anionic and neutral tetrazole forms, C- and N-mono- and C,N-disubstituted tetrazoles are considered.

Gaponik, Pavel N.; Voitekhovich, Sergei V.; Ivashkevich, Oleg A.

2006-06-01

334

Telomeric 30 Overhangs Derive  

E-print Network

Telomeric 30 Overhangs Derive from Resection by Exo1 and Apollo and Fill-In by POT1b-Associated CST and main- tenance of mammalian telomeres, but its synthesis must be regulated to avoid excessive resection of the 50 end, which could cause telomere shortening. How this balance is achieved in mammals has not been

de Lange, Titia

335

Nature's chemicals and synthetic chemicals: Comparative toxicology  

SciTech Connect

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.

Ames, B.N.; Profet, M.; Gold, L.S. (Univ. of California, Berkeley (USA))

1990-10-01

336

Tunable Raman spectroscopy study of CVD and peapod-derived bundled and individual double-wall carbon nanotubes  

E-print Network

We use 40 laser excitation energies to analyze the differences in the Raman spectra from chemical vapor deposition-derived double-wall carbon nanotube (CVD-DWNT) bundles, fullerene-derived DWNT bundles (C[subscript 60]-DWNTs), ...

Dresselhaus, Mildred

337

TECHNICAL BASIS FOR NARCOTIC CHEMICALS AND POLYCYCLIC AROMATIC HYDROCARBON CRITERIA. I. WATER AND TISSUE  

Microsoft Academic Search

A method is presented for developing water quality criteria (WQC) for type I narcotic chemicals in general and PAHs in particular. The criteria can be applied to any individual or mixture of narcotic chemicals using only the chemical's octanol-water partition coefficient KOW. It is derived from a database of LC50s comprising 156 chemicals and 33 species, including fish, amphibians, arthropods,

Dominic M. Di Toro; Joy A. McGrath; David J. Hansen

2000-01-01

338

40 CFR 721.4520 - Isopropylidene, bis(1,1-dimethylpropyl) derivative.  

Code of Federal Regulations, 2013 CFR

...Isopropylidene, bis(1,1-dimethylpropyl) derivative. 721.4520 Section 721.4520...Isopropylidene, bis(1,1-dimethylpropyl) derivative. (a) Chemical substance and significant...isopropylidene, bis(1,1-dimethylpropyl) derivative (PMN P-85-648) is subject...

2013-07-01

339

40 CFR 721.558 - Salt of a fatty alkylamine derivative (generic).  

Code of Federal Regulations, 2010 CFR

... false Salt of a fatty alkylamine derivative (generic). 721.558 Section...721.558 Salt of a fatty alkylamine derivative (generic). (a) Chemical substance...generically as a salt of a fatty alkylamine derivative (PMN P-96-1426) is subject...

2010-07-01

340

40 CFR 721.4520 - Isopropylidene, bis(1,1-dimethylpropyl) derivative.  

Code of Federal Regulations, 2012 CFR

...Isopropylidene, bis(1,1-dimethylpropyl) derivative. 721.4520 Section 721.4520...Isopropylidene, bis(1,1-dimethylpropyl) derivative. (a) Chemical substance and significant...isopropylidene, bis(1,1-dimethylpropyl) derivative (PMN P-85-648) is subject...

2012-07-01

341

40 CFR 721.558 - Salt of a fatty alkylamine derivative (generic).  

Code of Federal Regulations, 2011 CFR

... false Salt of a fatty alkylamine derivative (generic). 721.558 Section...721.558 Salt of a fatty alkylamine derivative (generic). (a) Chemical substance...generically as a salt of a fatty alkylamine derivative (PMN P-96-1426) is subject...

2011-07-01

342

40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.  

Code of Federal Regulations, 2011 CFR

...Oxo-substituted amino-al-kanoic acid derivative. 721.430 Section 721.430 ...Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical substance and significant...oxo-substituted amino al-kan-oic acid derivative (PMN No. P-92-692) is...

2011-07-01

343

40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.  

Code of Federal Regulations, 2012 CFR

...Oxo-substituted amino-al-kanoic acid derivative. 721.430 Section 721.430 ...Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical substance and significant...oxo-substituted amino al-kan-oic acid derivative (PMN No. P-92-692) is...

2012-07-01

344

40 CFR 721.430 - Oxo-substituted amino-al-kanoic acid derivative.  

Code of Federal Regulations, 2013 CFR

...Oxo-substituted amino-al-kanoic acid derivative. 721.430 Section 721.430 ...Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical substance and significant...oxo-substituted amino al-kan-oic acid derivative (PMN No. P-92-692) is...

2013-07-01

345

40 CFR 721.4520 - Isopropylidene, bis(1,1-dimethylpropyl) derivative.  

Code of Federal Regulations, 2011 CFR

...Isopropylidene, bis(1,1-dimethylpropyl) derivative. 721.4520 Section 721.4520...Isopropylidene, bis(1,1-dimethylpropyl) derivative. (a) Chemical substance and significant...isopropylidene, bis(1,1-dimethylpropyl) derivative (PMN P-85-648) is subject...

2011-07-01

346

40 CFR 721.4520 - Isopropylidene, bis(1,1-dimethylpropyl) derivative.  

Code of Federal Regulations, 2010 CFR

...Isopropylidene, bis(1,1-dimethylpropyl) derivative. 721.4520 Section 721.4520...Isopropylidene, bis(1,1-dimethylpropyl) derivative. (a) Chemical substance and significant...isopropylidene, bis(1,1-dimethylpropyl) derivative (PMN P-85-648) is subject...

2010-07-01

347

Iterative higher derivations: integrability Iterative higher derivations: axiomatization  

E-print Network

Multiplicatively iterative higher derivations D. Homann1 P. Kowalski2 1n/a 2Instytut Matematyczny Uniwersytetu Wrocªawskiego Logic Colloquium 2012, Manchester Homann, Kowalski Higher derivations #12;Iterative higher! = 0 !) Homann, Kowalski Higher derivations #12;Iterative higher derivations: integrability Iterative

Kowalski, Piotr

348

Treatment of biomass to obtain a target chemical  

DOEpatents

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.

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

349

Fractional Derivative Cosmology  

E-print Network

The degree by which a function can be differentiated need not be restricted to integer values. Usually most of the field equations of physics are taken to be second order, curiosity asks what happens if this is only approximately the case and the field equations are nearly second order. For Robertson-Walker cosmology there is a simple fractional modification of the Friedman and conservation equations. In general fractional gravitational equations similar to Einstein's are hard to define as this requires fractional derivative geometry. What fractional derivative geometry might entail is briefly looked at and it turns out that even asking very simple questions in two dimensions leads to ambiguous or intractable results. A two dimensional line element which depends on the Gamma-function is looked at.

Mark D. Roberts

2009-09-07

350

A persistent diazaheptacene derivative.  

PubMed

We describe the synthesis of characterizable diazaheptacene derivatives. Diazaheptacenes need four silylethynyl protecting groups to be isolable. TIPS-ethynyl groups are not bulky enough to allow stabilization. Four Si(sec-Bu)3-ethynyl groups symmetrically attached to the acene core sufficiently protect the formed diazaheptacene from dimerization through Diels-Alder reaction. It was characterized by NMR and UV-vis spectroscopies and cyclic voltammetry. PMID:25295844

Engelhart, Jens U; Tverskoy, Olena; Bunz, Uwe H F

2014-10-29

351

Functional Derivatives of Polyisobutene  

NASA Astrophysics Data System (ADS)

The methods of synthesis of isobutene polymers with end groups of different types are examined. It is shown that advances in the synthesis of these compounds are associated with the progress in the field of the regulation of the cationic polymerisation and copolymerisation of isobutene and the degradation of isobutene polymers and copolymers. Examples of the employment of functional derivatives of isobutene polymers in various branches of technology are presented. The bibliography includes 102 references.

Sangalov, Yu A.; Yasman, Yu B.

1985-07-01

352

Natural Products as Chemical Probes  

PubMed Central

Natural products have evolved to encompass a broad spectrum of chemical and functional diversity. It is this diversity, along with their structural complexity, that enables nature’s small molecules to target a nearly limitless number of biological macromolecules and to often do so in a highly selective fashion. Because of these characteristics, natural products have seen great success as therapeutic agents. However, this vast pool of compounds holds much promise beyond the development of future drugs. These features also make them ideal tools for the study of biological systems. Recent examples of the use of natural products and their derivatives as chemical probes to explore biological phenomena and assemble biochemical pathways are presented here. PMID:20509672

Carlson, Erin E.

2010-01-01

353

Olefin recovery via chemical absorption  

SciTech Connect

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.

Barchas, R. [Stone & Webster Engineering Corporation, Houston, TX (United States)

1998-06-01

354

Chemical and biological studies on Licania genus  

Microsoft Academic Search

This paper reports the phytochemical and biological studies carried out on several species of the Licania genus (Chrysobalanaceae). This genus includes many species mainly distributed in neotropical South American countries such as Venezuela, Brasil, and Mexico, most of them not yet investigated from the chemical and biological point of view. The name Licania derives from the anagram of the indigenous

Alessandra Braca; Anna Rita Bilia; Jeannette Mendez; Cosimo Pizza; Ivano Morelli; Nunziatina de Tommasi

2003-01-01

355

Organic chemical contaminants in Biosolids Sally Brown  

E-print Network

a head of lettuce and the plastic bag that you put it in at the supermarket are organic, carbon based to clean out the vegetable bin in the refrigerator can attest. Plastics, on the other hand, can persist and explains their behaviors and persistence. The names of different organic chemicals are often derived from

Brown, Sally

356

Dissolution kinetics of chemically amplified resists  

NASA Astrophysics Data System (ADS)

The dissolution rate characteristics of two typical DUV chemically amplified resists (negative resist A and positive resist B) were investigated, by comparing with an i-line novolac resist (resist C). The negative resist A here was based on crosslinking between phenolic resin and melamine derivatives, and the positive resist B was composed of tert-BOC protected phenolic resin.

Itani, Toshiro; Itoh, Katsuyuki; Kasama, Kunihiko

1993-09-01

357

Computation of Mie derivatives.  

PubMed

Analytical expressions are obtained for the derivatives of Mie scattering coefficients with respect to the electrical radius of the spherical scattering particle, and to the relative permittivity and permeability of both the particle and the surrounding medium. Their corresponding approximate expressions are developed to avoid numerical overflow based on the logarithmic derivative of Riccati-Bessel functions. The analytical expressions have been verified by comparing their results with those calculated by analytical expressions developed by Mathematica. Compared with the numerical derivative, the analytical expressions and approximate expressions show a higher accuracy and are 2.0 and 2.8 times, respectively, faster in the case of a single magnetodielectric sphere. Generally, for spheres with an electrical radius in a large range, the approximate expressions can yield acceptable accuracy and computation time up to a high order. This work can be used in the design of nonmetallic metamaterials, and in the retrieval of aerosol properties from remote sensing data. An example calculation is given for the design of an optical, all-dielectric, mu-negative metamaterial consisting of a simple cubic array of tellurium nanoparticles. PMID:23852216

Li, Yang; Bowler, Nicola

2013-07-10

358

The elusive chemical potential  

Microsoft Academic Search

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 applications-depression of the melting point and batteries-illustrate the chemical potential in action. The origin of the term ``chemical potential'' has its surprises, and a sketch of the

Ralph Baierlein

2001-01-01

359

Derivative computation by multiscale filters  

Microsoft Academic Search

It is a common problem to compute the derivative of a signal in image processing and computer vision. So far, in most of the computational methods, the nth order derivative of a noisy signal is obtained by filtering the signal by a nth Order Derivative Filter (NODF), which is the nth order derivative of a smooth filter. In order to

Song De Ma; Bingcheng Li

1998-01-01

360

Notion of a virtual derivative  

E-print Network

Diagrams as a graphic expresion of derivatives is proposed for calculation of derivatives for composed function. The concret diagram is understood as a virtual derivative in contrast of concret derivative. In polynomial expression of functions derivative the concret derivative will be every monomic member, and the virtual derivative represent the sum of similar monomic members. The word virtual denotes that we dont need to know every virtual derivative, we don't write all the sequence of these virtual derivatives, and simply pick the needed one. This is in contrast of tradition to write the whole algebraic expresion as a denotion of whole function's derivative. Such graphic expresion can be helpful in the problems of differential geometry, in the various asymptotic expantions, also in the solution of some differential equations.

Gintaras Valiukevicius

2011-01-04

361

Chemically defined generation of human cardiomyocytes.  

PubMed

Existing methods for human induced pluripotent stem cell (hiPSC) cardiac differentiation are efficient but require complex, undefined medium constituents that hinder further elucidation of the molecular mechanisms of cardiomyogenesis. Using hiPSCs derived under chemically defined conditions on synthetic matrices, we systematically developed an optimized cardiac differentiation strategy, using a chemically defined medium consisting of just three components: the basal medium RPMI 1640, L-ascorbic acid 2-phosphate and rice-derived recombinant human albumin. Along with small molecule-based induction of differentiation, this protocol produced contractile sheets of up to 95% TNNT2(+) cardiomyocytes at a yield of up to 100 cardiomyocytes for every input pluripotent cell and was effective in 11 hiPSC lines tested. This chemically defined platform for cardiac specification of hiPSCs will allow the elucidation of cardiomyocyte macromolecular and metabolic requirements and will provide a minimal system for the study of maturation and subtype specification. PMID:24930130

Burridge, Paul W; Matsa, Elena; Shukla, Praveen; Lin, Ziliang C; Churko, Jared M; Ebert, Antje D; Lan, Feng; Diecke, Sebastian; Huber, Bruno; Mordwinkin, Nicholas M; Plews, Jordan R; Abilez, Oscar J; Cui, Bianxiao; Gold, Joseph D; Wu, Joseph C

2014-08-01

362

Bacterial degradation of chlorophenols and their derivatives.  

PubMed

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

Arora, Pankaj Kumar; Bae, Hanhong

2014-01-01

363

Bacterial degradation of chlorophenols and their derivatives  

PubMed Central

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

2014-01-01

364

Cytotoxic apigenin derivatives from Chrysopogon aciculatis.  

PubMed

Four new apigenin derivatives, 7-de-O-methylaciculatin, 8-C-?-D-boivinopyranosylapigenin, aciculatinone, and 4'-O-glucosylaciculatin, along with eight known compounds, apigenin-8-carbaldehyde, kaempferol, tricin, taxifolin, 6,7,4'-trihydroxyflavone, trans-oxyresveratrol, aciculatin, and luteolin-7-sulfate, were isolated from an ethanolic extract of Chrysopogon aciculatis. Their chemical structures were elucidated by spectroscopic methods. Among the known compounds, the natural occurrence of apigenin-8-carbaldehyde and luteolin-7-sulfate is demonstrated for the first time. Some of the isolates were evaluated for cytotoxic activity against human cancer cell lines including MCF-7, H460, HT-29, and CEM. PMID:22272829

Shen, Chien-Chang; Cheng, Jing-Jy; Lay, Horng-Liang; Wu, Szu-Yuan; Ni, Ching-Li; Teng, Che-Ming; Chen, Chien-Chih

2012-02-24

365

Chemical engineers design, control and optimize large-scale chemical,  

E-print Network

38 Chemical engineers design, control and optimize large-scale chemical, physicochemical and electronics fields. Chemical Engineers are employed in areas as diverse as the chemical, pharmaceutical, petrochemical and environmental industries. Emerging fields in chemical engineering include biotechnology

Rohs, Remo

366

Platform Chemicals from an Oilseed Biorefinery  

SciTech Connect

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.

Tupy, Mike; Schrodi Yann

2006-11-06

367

Analysis of multicomponent gas mixture flows with partial chemical equilibrium  

Microsoft Academic Search

Diffusion equations and the corresponding transfer equations with effective transfer coefficients are derived using new unknown functions (linear combinations of diffusion fluxes and of concentrations) for reactive gas mixture flows with partial chemical equilibrium. The diffusion differential equations for rapid independent reactions degenerate into algebraic equations of detailed chemical equilibrium. The component formation sources on the right-hand sides of the

O. N. Suslov; E. I. Fateeva

1996-01-01

368

Systematic design of chemical oscillators using complexation and precipitation equilibria  

Microsoft Academic Search

Concentration oscillations are ubiquitous in living systems, where they involve a wide range of chemical species. In contrast, early in vitro chemical oscillators were all derived from two accidentally discovered reactions based on oxyhalogen chemistry. Over the past 25years, the use of a systematic design algorithm, in which a slow feedback reaction periodically drives a bistable system in a flow

Krisztina Kurin-Csörgei; Irving R. Epstein; Miklós Orbán

2005-01-01

369

CHEMICAL ENGINEERING AND MANUFACTURING CHEMICAL ENGINEERING  

E-print Network

, completion, attention to detail, etc. Materials 1. Cookies 2. Frosting 3. Food coloring 4. Sprinkles 5 are involved in the production of food, cosmetics, fuels, and anything else that requires the mixing of chemicals. This lesson introduces students to one component of chemical engineering: food processing

Provancher, William

370

The Chemical Heritage Foundation  

NASA Astrophysics Data System (ADS)

This first in a series of articles on the Chemical Heritage Foundation will outline a brief history of the foundation and give an overview of its present programs, with emphasis on the Othmer Library of Chemical History. The Chemical Heritage Foundation (CHF) is a unique asset and unique partnership of the chemical community. It had its origins in a simple written agreement some 15 years ago, in January 1982. CHF's mission of recording, preserving, and making known the heritage of chemical achievement does not reflect the concerns of the chemical corporations or of anyone directly concerned with the "image" or economic and political future of the chemical sciences. Rather, it was an idea of academics and professional scientists. Thus it was appropriate that the three founding organizations were the American Chemical Society, the American Institute of Chemical Engineers and the University of Pennsylvania.

Orna, Mary Virginia

1998-04-01

371

Derivation of equations describing solute transport in ground water  

USGS Publications Warehouse

A general equation describing the three-dimensional transport and dispersion of a reacting solute in flowing ground water is derived from the principle of conservation of mass. The derivation presented is more detailed but less rigorous than derivations published previously. The general solute-transport equation relates concentration changes to hydrodynamic dispersion, convective transport, fluid sources and sinks, and chemical reactions. Because both dispersion and convective transport depend on the velocity of ground-water flow, the solute-transport equation must be solved in conjunction with the ground-water flow equation. (Woodard-USGS)

Konikow, L.F.; Grove, D.B.

1977-01-01

372

Chemical Methods for the Synthesis and Modification of Neoclerodane Diterpenes  

PubMed Central

Diterpenes are a structural class of molecules that are derived from four isoprene subunits and are widespread throughout nature. A number of neoclerodane diterpenes have been found to have biological activity but a limited number of chemical investigations have been conducted. Recently, the neoclerodane diterpene, salvinorin A (12) has been investigated due to its unique pharmacological profile. This review will discuss the chemical methods used to chemically modify and synthesize 12. PMID:19679471

Lozama, Anthony; Prisinzano, Thomas E.

2009-01-01

373

Components in Chemical Thermodynamics  

NASA Astrophysics Data System (ADS)

Chemical equations are actually matrix equations, and this has important implications for their thermodynamic treatment. The fundamental equation for chemical thermodynamics for a chemical reaction system can be written in terms of species, but at chemical equilibrium, it has to be written in terms of components. The number of components is equal to the number of species minus the number of independent chemical reactions. The fundamental equation for the Gibbs energy of a system containing ethylene, methane, ethane, and propane is discussed. At chemical equilibrium there are two components, which can be taken to be carbon and hydrogen or ethylene and methane. There are advantages in using matrix notation.

Alberty, Robert A.

1995-09-01

374

Acquiring Knowledge of Derived Nominals and Derived Adjectives in Context  

ERIC Educational Resources Information Center

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…

Marinellie, Sally A.; Kneile, Lynn A.

2012-01-01

375

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

...N-coco acyl derivs., inner salts. 721.10193 Section 721...N-coco acyl derivs., inner salts. (a) Chemical substance...N-coco acyl derivs., inner salts (PMN P-06-263, Chemical...uses are: (i) Release to water . Requirements as...

2010-07-01

376

40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.  

Code of Federal Regulations, 2013 CFR

...N-coco acyl derivs., inner salts. 721.10193 Section 721...N-coco acyl derivs., inner salts. (a) Chemical substance...N-coco acyl derivs., inner salts (PMN P-06-263, Chemical...uses are: (i) Release to water . Requirements as...

2013-07-01

377

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

...N-coco acyl derivs., inner salts. 721.10193 Section 721...N-coco acyl derivs., inner salts. (a) Chemical substance...N-coco acyl derivs., inner salts (PMN P-06-263, Chemical...uses are: (i) Release to water . Requirements as...

2011-07-01

378

Polymeric derivatives of plant growth regulators: synthesis and properties  

Microsoft Academic Search

The polymeric formulations of plant growth regulators (PGRs) are high molecular weight systems in which the PGR unit is attached to the polymeric chain by a hydrolysable chemical bond. These polymeric derivatives (esters, ethers, or else) of PGRs are characterised by the ability to release the active compound (PGR) from their solutions (mainly aqueous) in certain conditions. The release of

Aristidis M. Tsatsakis; Michail I. Shtilman

1994-01-01

379

Quantum Hydrodynamic models derived from the entropy principle  

Microsoft Academic Search

In this work, we give an overview of recently derived quantum hydrodynamic and diffusion models. A quantum local equilibrium is defined as a minimizer of the quantum entropy subject to local moment constraints (such as given local mass, momentum and energy densities). These equilibria relate the thermodynamic parameters (such as the temperature or chemical potential) to the densities in a

Pierre Degond; Florian Mehats; Christian Ringhofer

380

Advanced chemical lasers  

Microsoft Academic Search

A review of recent advances in chemical laser technology is presented. New technology and concepts related to the Chemical Oxygen Iodine Laser (COIL), All Gas-phase Iodine Laser (AGIL), and HF Overtone Laser are discussed.

Gerald C. Manke II; Kevin B. Hewett; Timothy J. Madden; John E. McCord; Charles F. Wisniewski; Gordon D. Hager

2004-01-01

381

Children and Dairy Chemicals  

MedlinePLUS

Children & Dairy Chemicals Chemicals used to clean dairy facilities and equipment, especially dairy pipeline cleaners, pose a special risk for children. Rapid medical assessment and treatment is critical in preventing long ...

382

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

383

Chemistry 455 Chemical Nanotechnology  

E-print Network

Chemistry 455 Chemical Nanotechnology 4 units Prof. Richard Brutchey, Fall 2014 (Lecture = 12:00�12:50 pm MWF) CHEM 455 is an upper-division undergraduate course in Chemical Nanotechnology. The intent

Rohs, Remo

384

PhD Chemical Engineering MS Chemical Engineering  

E-print Network

1 PhD Chemical Engineering MS Chemical Engineering Bylaws Gene and Linda Voiland School of ChemicalD Chemical Engineering, MS Chemical Engineering B. Discipline: Edgar, et al.1 provide a succinct description of chemical engineering: "chemical engineers seek to understand, manipulate, and control the molecular basis

Collins, Gary S.

385

The elusive chemical potential  

NSDL National Science Digital Library

The author 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 applications â depression of the melting point and batteries â illustrate the chemical potential in action. The origin of the term "chemical potential" has its surprises, and a sketch of the history is given.variable particle number.

Baierlein, Ralph

2011-08-31

386

Chemical Synthesis Database  

NSDL National Science Digital Library

This database provides information on thousands of chemical compounds, including synthesis references and physical properties. The database is searchable by keyword and browseable by journal title. For each compound, the information includes molecular formula and weight, Chemical Abstracts Service (CAS) numbers, International Chemical Identifier (InChIKey), and Simplified Molecular Input Line Entry System (SMILES) notation. There is also information on synonyms, physical properties (boiling and melting points, density), an illustration of chemical structure, spectral data, and links to additional data.

387

Chemical of the Week  

NSDL National Science Digital Library

Professor Bassam Z. Shakhashiri at the University of Wisconsin-Madison adds a new chemical to this page every week. The site was created for his general chemistry courses, Chem 103 and Chem 104, to increase students' knowledge about various chemicals and their use. Users can view featured chemicals from the currently updated fall course (103) or from the spring course (104). The chemicals featured thus far include: lime, methane, uranium, the chemistry of autumn colors, and gases that emit light.

Shakhashiri, Bassam Z.

2007-05-30

388

Antistaphylococcal activity of novel salicylanilide derivatives.  

PubMed

This study examined the antibacterial properties of nineteen benzoxazole, isoniazid, ethionamide and salicylanilide derivatives against Staphylococcus aureus (S. aureus). It was found that three salicylanilide-derived compounds demonstrated antistaphylococcal activity: 5-Chloro-2-hydroxy-N-(4-(trifluoromethyl)phenyl)benzamide (5-Cl-4'-CF3- SAL), 4-chloro-2-(3-chlorophenylcarbamyoyl)phenyl)-2-(benzyloxycarbonylamino)propanoate (AIM31) and 4-chloro-2- (4-(trifluoromethyl)phenylcarbamoyl)phenyl acetate (AIM33). Investigation of the chemical structures of these three compounds and comparison with a non-inhibitory salicylanilide compound (i.e. 5,3'-diCl-SAL) illustrated that different combinations of chemical groups at defined positions on the salicylanilide core structure had a marked influence on antistaphylococcal activity. The most effective compound was AIM33 which inhibited staphylococcal growth and displayed an initial MIC value of 3.12 ?g ml(-1) and subsequent investigation revealed that an MIC as low as of 0.5 ?g ml(-1) was achievable. In this case, the dual presence of a trifluoromethyl group and an acetylated phenolic hydroxyl to the salicylanilide core structure led to greatly enhanced activity. PMID:21644919

Mollaghan, Annmarie; Vinsova, Jarmila; Imramovsky, Ales; Cotter, Lesley; Lucey, Brigid; O'Mahony, Jim; Costelloe, Aisling; Coffey, Aidan

2012-03-01

389

Chemicals for worldwide aquaculture  

USGS Publications Warehouse

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.

Schnick, R.A.

1991-01-01

390

Toxicology and Chemical Safety.  

ERIC Educational Resources Information Center

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)

Hall, Stephen K.

1983-01-01

391

Chemical and Environmental Technology.  

ERIC Educational Resources Information Center

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…

Sheather, Harry

392

Chemical Reactions at Surfaces  

Microsoft Academic Search

Chemical reactions at surfaces underlie some of the most important processes of today, including catalysis, energy conversion, microelectronics, human health and the environment. Understanding surface chemical reactions at a fundamental level is at the core of the field of surface science. The Gordon Research Conference on Chemical Reactions at Surfaces is one of the premiere meetings in the field. The

Nancy Ryan Gray Michael Henderson

2010-01-01

393

More on Chemical Changes  

NSDL National Science Digital Library

The phenomenon is a series of chemical reactions and observation of signs of a chemical change. The laboratory activities can be done by students or as a teacher demonstration. They involve mixing chemicals and noting color change, formation of a precipitate, and production of a gas.

394

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...

395

Chemical earth models  

NASA Astrophysics Data System (ADS)

This article presents a critical review of method, concepts and prejudices used bv modelists of the Earth's chemical composition over approximate the last fifty years and of the resulting compositions. Brief descriptions are given of admitted accretion mechanisms, of the starting materials most often considered and of the major parameters and recurrent concepts: 'reduced" state, mantle homogeneity vs heterogeneity, 'low pressure' core formation, 'great impact', refractory, lithophile, siderophile, compatible, incompatible character of elements, depleted and degassed mantle, Urey ratio, as well as the description of a commonly-used instrument, possibly harmful to Iogic, the famous Ockham's razor. Differences between models are now restricted to the lower mantle composition:the 'primary' (before crust differentiation) upper mentle varies little from model to model and the idea of a 10-15% combined Si-O-S concentration as representing the necessary light elements in the core is gaining more and more ground. The dominant type of model derives more or less directly from the CI cabonaceous composition by complete devolatilization and reduction. Its mantle is homogeneous and convecting mainly in a one-level mode, in accordence with dominant geophysicists' views but in rather strong disagreement with geochemical data and models which insist on the strong decoupling between lower and upper mantle. Its low Si excess is generally supposed to have been absorbed by the core, whereas its high refractory lithophile element (RLE) content creates mass balance problems relative to presently observed mantle and crust concentrations. The alternative type is a two-lavel mantle with a Si and Fe-rich, RLE-poor, lower mantle, previously based mainly on seismic and mineral physics data, and now also on geochemical and cosmochemical arguments.

Javoy, Marc

1999-10-01

396

Higher-derivative 3-algebras  

E-print Network

Starting with the N=8 supersymmetric Yang-Mills theory on D2-branes and incorporating higher-derivative corrections to lowest nontrivial order, we perform a duality to derive the Lorentzian 3-algebra theory along with a set of derivative corrections. We find that these corrections can be expressed entirely in terms of intrinsic 3-algebra quantities: the 3-bracket and covariant derivatives. Our analysis is performed for both bosonic and fermionic terms. We conjecture that the derivative corrections we obtain are relevant for Euclidean 3-algebra theories as well.

Mohsen Alishahiha; Sunil Mukhi

2008-08-22

397

Make a Chemical Clock  

NSDL National Science Digital Library

This lesson for Grades 6-8 combines a short video with three experiments to observe and record chemical changes. The experiments use common household materials to demonstrate chemical reaction -- a change that leads to a transformation of one substance into another substance. In the 3rd experiment, there are two chemical reactions happening at the same time. Through careful observation, learners see that the 3rd reaction represents a "chemical clock", because the time it takes the chemicals to react happens very predictably, like a regular clock. Talking Science is part of National Public Radio's Science Friday initiative.

2011-08-18

398

Chemical Synthesis of Proteins  

PubMed Central

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

Nilsson, Bradley L.; Soellner, Matthew B.; Raines, Ronald T.

2010-01-01

399

Radioactively labelled porphyrin derivatives  

NASA Astrophysics Data System (ADS)

Radioactive labelling of guanidine-bearing tetraphenylporphyrin and Dy—texaphyrin with selected radionuclides (166Ho and 90Y) is described. A basic characterisation of studied porphyrin and texaphyrin, including their behaviour in a wide range of pH values and data on holmium and yttrium complexation with these compounds was probed using UV-VIS absorption spectrometry. The labelling yield of these macrocyclic molecules depends on the pH of the reaction mixture, metal: ligand ratio and time of incubation. Optimal reaction conditions for formation of porphyrin and texaphyrin radioactive complexes were determined by thin layer chromatography with the detection of ?- activity. The ability of porphyrin derivatives to bind anions was examined as well. Our experiments were focused on perrhenate ion (ReO4 -) because radiopharmaceuticals labelled with isotopes 186Re and 188Re play an important role in therapy of numerous tumour diseases. The possibility of applying ReO4 - anion directly for labelling purposes, without the necessity of its reduction to lower oxidation state, was not proved.

Koní?ová, R.; Ernestová, M.; Jedináková-K?ížová, V.; Král, V.

2003-01-01

400

Vaccine-derived polioviruses.  

PubMed

The attenuated oral poliovirus vaccine (OPV) has many properties favoring its use in polio eradication: ease of administration, efficient induction of intestinal immunity, induction of durable humoral immunity, and low cost. Despite these advantages, OPV has the disadvantage of genetic instability, resulting in rare and sporadic cases of vaccine-associated paralytic poliomyelitis (VAPP) and the emergence of genetically divergent vaccine-derived polioviruses (VDPVs). Whereas VAPP is an adverse event following exposure to OPV, VDPVs are polioviruses whose genetic properties indicate prolonged replication or transmission. Three categories of VDPVs are recognized: (1) circulating VDPVs (cVDPVs) from outbreaks in settings of low OPV coverage, (2) immunodeficiency-associated VDPVs (iVDPVs) from individuals with primary immunodeficiencies, and (3) ambiguous VDPVs (aVDPVs), which cannot be definitively assigned to either of the first 2 categories. Because most VDPVs are type 2, the World Health Organization's plans call for coordinated worldwide replacement of trivalent OPV with bivalent OPV containing poliovirus types 1 and 3. PMID:25316847

Burns, Cara C; Diop, Ousmane M; Sutter, Roland W; Kew, Olen M

2014-11-01

401

Do metformin a real anticarcinogen? A critical reappraisal of experimental data  

PubMed Central

Evidence has emerged that antidiabetic biguanides [phenformin (PF), buformin (BF) and metformin (MF)] are promising candidates for prevention of cancer. It was shown that antidiabetic biguanides postpone spontaneous carcinogenesis as well as inhibit carcinogenesis induced by chemical, radiation and biological factors (virus, transgene, genetic modifications, special diet, etc.) in a number of organs and tissues in various strains of mice and rats. The present review focused on some details of experiments such as design of studies, dose and route of administration of biguanide, and age of animals at start of treatment etc. Conclusion may be done that there are rather sufficient evidence of cancer-preventive activity of antidiabetic biguanides in experimental animals. PMID:25333035

2014-01-01

402

Chemical exchange program analysis.  

SciTech Connect

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.

Waffelaert, Pascale

2007-09-01

403

Experts' understanding of partial derivatives using the Partial Derivative Machine  

E-print Network

Partial derivatives are used in a variety of different ways within physics. Most notably, thermodynamics uses partial derivatives in ways that students often find confusing. As part of a collaboration with mathematics faculty, we are at the beginning of a study of the teaching of partial derivatives, a goal of better aligning the teaching of multivariable calculus with the needs of students in STEM disciplines. As a part of this project, we have performed a pilot study of expert understanding of partial derivatives across three disciplines: physics, engineering and mathematics. Our interviews made use of the Partial Derivative Machine (PDM), which is a mechanical system featuring four observable and controllable properties, of which any two are independent. Using the PDM, we probed expert understanding of partial derivatives in an experimental context in which there is not a known functional form. Through these three interviews, we found that the mathematicians exhibited a striking difference in their underst...

Roundy, David; Dray, Tevian; Manogue, Corinne A; Weber, Eric

2014-01-01

404

Chemical Hygiene Plan i January 2013 Chemical Hygiene Plan  

E-print Network

Chemical Hygiene Plan i January 2013 Chemical Hygiene Plan (CHP) (Appendix C in Lab Safety Manual........................................................................................................................1-1 Chapter 2: Chemical Hazard Communication....................................................................................2-1 Chapter 3: Classes of Hazardous Chemicals

Nizkorodov, Sergey

405

Digital and analog chemical evolution.  

PubMed

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

Goodwin, Jay T; Mehta, Anil K; Lynn, David G

2012-12-18

406

Chemical space networks: a powerful new paradigm for the description of chemical space.  

PubMed

The concept of chemical space is playing an increasingly important role in many areas of chemical research, especially medicinal chemistry and chemical biology. It is generally conceived as consisting of numerous compound clusters of varying sizes scattered throughout the space in much the same way as galaxies of stars inhabit our universe. A number of issues associated with this coordinate-based representation are discussed. Not the least of which is the continuous nature of the space, a feature not entirely compatible with the inherently discrete nature of chemical space. Cell-based representations, which are derived from coordinate-based spaces, have also been developed that facilitate a number of chemical informatic activities (e.g., diverse subset selection, filling 'diversity voids', and comparing compound collections).These representations generally suffer the 'curse of dimensionality'. In this work, networks are proposed as an attractive paradigm for representing chemical space since they circumvent many of the issues associated with coordinate- and cell-based representations, including the curse of dimensionality. In addition, their relational structure is entirely compatible with the intrinsic nature of chemical space. A description of the features of these chemical space networks is presented that emphasizes their statistical characteristics and indicates how they are related to various types of network topologies that exhibit random, scale-free, and/or 'small world' properties. PMID:24925682

Maggiora, Gerald M; Bajorath, Jürgen

2014-08-01

407

Journal of Chemical Education: Chemical Resource Shelf  

NSDL National Science Digital Library

Produced under the auspices of the Journal of Chemical Education Online, this site is the basis for that journal's "Book Buyer's Guide." It provides high school and college-level chemistry educators with various teaching resources, including a comprehensive index to chemistry textbooks in print. The index is arranged by subject, under which entries are listed in chronological order, from newest to oldest. Subjects covered range from Biochemistry and Computers in Chemistry to Quantum Chemistry and Writing in Science. In addition to basic bibliographic information, when available, each entry includes citations of reviews and links to publishers' online catalogs. Another feature is "Hal's Picks of the Month," a growing archive of over 30 "books and recent articles for teachers of chemistry and related sciences" as recommended and reviewed by Professor Harold (Hal) Harris of the University of Missouri - St. Louis Chemistry Department. "Journals of Interest to Chemical Educators" and "Suppliers of Software for Chemical Education" are two other lists available at this site.

1995-01-01

408

Chemical evolution STRUCTURE OF GALAXIES  

E-print Network

Outline Absorption Chemical evolution STRUCTURE OF GALAXIES 8. Absorption; chemical evolution Piet Piet van der Kruit, Kapteyn Astronomical Institute Absorption; chemical evolution #12;Outline Absorption Chemical evolution Outline Absorption Holmberg's analysis Analysis of Disney et al. Edge

Kruit, Piet van der

409

40 CFR 721.9078 - 6-Methoxy-1H-benz[de]isoquinoline-2 [3H]-dione derivative (generic).  

Code of Federal Regulations, 2012 CFR

...de]isoquinoline-2 [3H]-dione derivative (generic). 721.9078 Section...de]isoquinoline-2 [3H]-dione derivative (generic). (a) Chemical substance...de]isoquinoline-2 [3H]-dione derivative (PMN P-00-1205) is subject...

2012-07-01

410

40 CFR 721.9078 - 6-Methoxy-1H-benz[de]isoquinoline-2 [3H]-dione derivative (generic).  

Code of Federal Regulations, 2010 CFR

...de]isoquinoline-2 [3H]-dione derivative (generic). 721.9078 Section...de]isoquinoline-2 [3H]-dione derivative (generic). (a) Chemical substance...de]isoquinoline-2 [3H]-dione derivative (PMN P-00-1205) is subject...

2010-07-01

411

40 CFR 721.9078 - 6-Methoxy-1H-benz[de]isoquinoline-2 [3H]-dione derivative (generic).  

Code of Federal Regulations, 2011 CFR

...de]isoquinoline-2 [3H]-dione derivative (generic). 721.9078 Section...de]isoquinoline-2 [3H]-dione derivative (generic). (a) Chemical substance...de]isoquinoline-2 [3H]-dione derivative (PMN P-00-1205) is subject...

2011-07-01

412

40 CFR 721.10539 - Bis[phenyl-2H-1,3-benzoxazine]derivative (generic).  

Code of Federal Regulations, 2013 CFR

...phenyl-2H-1,3-benzoxazine]derivative (generic). 721.10539 Section...phenyl-2H-1,3-benzoxazine]derivative (generic). (a) Chemical substance...phenyl-2H-1,3-benzoxazine]derivative (PMN P-02-653) is subject...

2013-07-01

413

40 CFR 721.9078 - 6-Methoxy-1H-benz[de]isoquinoline-2 [3H]-dione derivative (generic).  

Code of Federal Regulations, 2013 CFR

...de]isoquinoline-2 [3H]-dione derivative (generic). 721.9078 Section...de]isoquinoline-2 [3H]-dione derivative (generic). (a) Chemical substance...de]isoquinoline-2 [3H]-dione derivative (PMN P-00-1205) is subject...

2013-07-01

414

40 CFR 721.10321 - Bis[phenyl, 2H-1,3-benzoxazine]derivative (generic).  

Code of Federal Regulations, 2012 CFR

...phenyl, 2H-1,3-benzoxazine]derivative (generic). 721.10321 Section...phenyl, 2H-1,3-benzoxazine]derivative (generic). (a) Chemical substance...phenyl, 2H-1,3-benzoxazine]derivative (PMN P-03-194) is subject...

2012-07-01

415

40 CFR 721.10321 - Bis[phenyl, 2H-1,3-benzoxazine]derivative (generic).  

Code of Federal Regulations, 2013 CFR

...phenyl, 2H-1,3-benzoxazine]derivative (generic). 721.10321 Section...phenyl, 2H-1,3-benzoxazine]derivative (generic). (a) Chemical substance...phenyl, 2H-1,3-benzoxazine]derivative (PMN P-03-194) is subject...

2013-07-01

416

Alternative Fuels and Chemicals From Synthesis Gas  

SciTech Connect

The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

none

1998-07-01

417

ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS  

SciTech Connect

The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

Unknown

1998-01-01

418

ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS  

SciTech Connect

The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

Unknown

1999-01-01

419

Metamorphic chemical geodynamics of subduction zones  

Microsoft Academic Search

Study of metamorphic suites directly representing the deep subduction of altered oceanic crust and sediments can help elucidate the geochemical evolution of the forearc-to-subarc slab mantle interface, the nature of slab-derived fluids added to arc lava source regions, and the chemical changes in subducting rocks potentially contributing to the geochemical heterogeneity of the deeper mantle. The stage is set for

Gray E. Bebout

2007-01-01

420

ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS  

SciTech Connect

The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

Peter J. Tijrn

2000-06-30

421

ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS  

SciTech Connect

The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

Unknown

1999-04-01

422

Alternative fuels and chemicals from synthesis gas  

SciTech Connect

The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

Unknown

1998-08-01

423

Photoelectrochemical hydrogen production from biomass derivatives and water.  

PubMed

Hydrogen, a clean energy carrier with high energy capacity, is a very promising candidate as a primary energy source for the future. Photoelectrochemical (PEC) hydrogen production from renewable biomass derivatives and water is one of the most promising approaches to producing green chemical fuel. Compared to water splitting, hydrogen production from renewable biomass derivatives and water through a PEC process is more efficient from the viewpoint of thermodynamics. Additionally, the carbon dioxide formed can be re-transformed into carbohydrates via photosynthesis in plants. In this review, we focus on the development of photoanodes and systems for PEC hydrogen production from water and renewable biomass derivatives, such as methanol, ethanol, glycerol and sugars. We also discuss the future challenges and opportunities for the design of the state-of-the-art photoanodes and PEC systems for hydrogen production from biomass derivatives and water. PMID:24599050

Lu, Xihong; Xie, Shilei; Yang, Hao; Tong, Yexiang; Ji, Hongbing

2014-10-20

424

Chitooligosaccharide and Its Derivatives: Preparation and Biological Applications  

PubMed Central

Chitin is a natural polysaccharide of major importance. This biopolymer is synthesized by an enormous number of living organisms; considering the amount of chitin produced annually in the world, it is the most abundant polymer after cellulose. The most important derivative of chitin is chitosan, obtained by partial deacetylation of chitin under alkaline conditions or by enzymatic hydrolysis. Chitin and chitosan are known to have important functional activities but poor solubility makes them difficult to use in food and biomedicinal applications. Chitooligosaccharides (COS) are the degraded products of chitosan or chitin prepared by enzymatic or chemical hydrolysis of chitosan. The greater solubility and low viscosity of COS have attracted the interest of many researchers to utilize COS and their derivatives for various biomedical applications. In light of the recent interest in the biomedical applications of chitin, chitosan, and their derivatives, this review focuses on the preparation and biological activities of chitin, chitosan, COS, and their derivatives. PMID:24724091

Lodhi, Gaurav; Hwang, Jin-Woo; Kim, Se-Kwon; Jeon, You-Jin; Je, Jae-Young; Ahn, Chang-Bum; Moon, Sang-Ho; Jeon, Byong-Tae; Park, Pyo-Jam

2014-01-01

425

Chemically pumped iodine laser  

Microsoft Academic Search

McDermott et al. (1978) have developed a practical O2(1 Delta) generator based on bubbling Cl2 in alkaline H2O2. In the work described in the present paper, it proved possible to convert a transverse-flow mixing chemical laser, originally designed as a CO chemical laser, to a chemical iodine-atom laser by installing a version of the McDermott generator on the laser. The

R. J. Richardson; C. E. Wiswall

1979-01-01

426

Insect Chemical Warfare  

NSDL National Science Digital Library

Discussion of the Bombardier beetle's chemical defense, detailing the explosive qualities of the chemicals, where the beetle is found, a bit about distribution, and what the chemicals do to people. There's also a bit about insects in the news detailing the beetle's role in the ongoing religious debate as it pertains to how such an animal might evolve, with an aside about a Richard Dawkin's demonstration.

0002-11-30

427

Chemical spill exposure assessment  

Microsoft Academic Search

POSSM, the PCB On-Site Spill Model, is a contaminant transport model developed to predict environmental concentrations associated with a chemical spill. The model predicts daily changes in chemical concentrations on a spill site (e.g., in soil and on vegetation) and losses of chemical due to volatilization, surface runoff\\/soil erosion, and leaching to groundwater. Spill areas consisting of soil\\/vegetation and\\/or an

Stuart M. Brown; Abraham Silvers

1986-01-01

428

Multivariate Quantitative Chemical Analysis  

NASA Technical Reports Server (NTRS)

Technique of multivariate quantitative chemical analysis devised for use in determining relative proportions of two components mixed and sprayed together onto object to form thermally insulating foam. Potentially adaptable to other materials, especially in process-monitoring applications in which necessary to know and control critical properties of products via quantitative chemical analyses of products. In addition to chemical composition, also used to determine such physical properties as densities and strengths.

Kinchen, David G.; Capezza, Mary

1995-01-01

429

Limits and Derivatives: The Derivative as a Function  

NSDL National Science Digital Library

Sketch the graph of the derivative of a geometrically represented function;Explain the correspondence between the sign of the derivative on an interval and the monotonicity of the function on that interval. Classify the basic ways in which a function may fail to be differentiable.

Freeze, Michael

2003-01-22

430

Accurate Calculation, Prediction, and Assignment of 3 Chemical Shifts of Helium-3-Encapsulated Fullerenes and  

E-print Network

of fullerene derivatives than in parent C60 and C70 spectra. It is difficult, even impossible, to assign the 13-Encapsulated Fullerenes and Fullerene Derivatives Guan-Wu Wang,*, Xin-Hao Zhang, Huan Zhan, Qing-Xiang Guo-3 NMR chemical shifts of various 3 He-encapsulated fullerenes (3 He@Cn) and their derivatives have

Wang, Guan-Wu

431

Chemically Layered Porous Solids  

NASA Technical Reports Server (NTRS)

Aerogels and other porous solids in which surfaces of pores have chemical properties varying with depth below macroscopic surfaces prepared by sequences of chemical treatments. Porous glass or silica bead treated to make two depth zones having different chemical properties. Beads dropped along tube filled with flowing gas containing atomic oxygen, generated in microwave discharge. General class of materials treatable include oxides of aluminum, silicon, zirconium, tin, titanium, and nickel, and mixtures of these oxides. Potential uses of treated materials include chromatographic separations, membrane separations, controlled releases of chemicals, and catalysis.

Koontz, Steve

1991-01-01

432

Physical and Chemical Changes  

NSDL National Science Digital Library

Physical and chemical changes in matter affect us every day. Use the following resources to help you understand these changes more completely. Read this document to help you understand the difference between physical and chemical changes in matter. definitions Watch this! It illustrates the physical change of matter. physical change video Now, watch this! It illustrates the chemical change of matter. chemical change video Click on this link to read and explore the Utah Science Sci-ber Site. It will help you to ...

Holly, Mrs.

2010-11-15

433

310 Facility chemical specifications  

SciTech Connect

The 300 area Treated Effluent Disposal Facility (TEDF) was designed and built to treat the waste water from the 300 area process sewer system. Several treatment technologies are employed to remove the trace quantities of contaminants in the stream, including iron coprecipitation, clarification, filtration, ion exchange, and ultra violet light/hydrogen peroxide oxidation of organics. The chemicals that will be utilized in the treatment process are hydrogen peroxide, sulfuric acid, sodium hydroxide, and ferric chloride. This document annotates the required chemical characteristics of TEDF bulk chemicals as well as the criteria that were used to establish these criteria. The chemical specifications in appendix B are generated from this information.

Hagerty, K.J.

1997-05-21

434

Apparatus for chemical synthesis  

DOEpatents

A method and apparatus for forming a chemical hydride is described and which includes a pseudo-plasma-electrolysis reactor which is operable to receive a solution capable of forming a chemical hydride and which further includes a cathode and a movable anode, and wherein the anode is moved into and out of fluidic, ohmic electrical contact with the solution capable of forming a chemical hydride and which further, when energized produces an oxygen plasma which facilitates the formation of a chemical hydride in the solution.

Kong, Peter C. (Idaho Falls, ID); Herring, J. Stephen (Idaho Falls, ID); Grandy, Jon D. (Idaho Falls, ID)

2011-05-10

435

Predicting Chemical Toxicity Effects Based on Chemical-Chemical Interactions  

PubMed Central

Toxicity is a major contributor to high attrition rates of new chemical entities in drug discoveries. In this study, an order-classifier was built to predict a series of toxic effects based on data concerning chemical-chemical interactions under the assumption that interactive compounds are more likely to share similar toxicity profiles. According to their interaction confidence scores, the order from the most likely toxicity to the least was obtained for each compound. Ten test groups, each of them containing one training dataset and one test dataset, were constructed from a benchmark dataset consisting of 17,233 compounds. By a Jackknife test on each of these test groups, the 1st order prediction accuracies of the training dataset and the test dataset were all approximately 79.50%, substantially higher than the rate of 25.43% achieved by random guesses. Encouraged by the promising results, we expect that our method will become a useful tool in screening out drugs with high toxicity. PMID:23457578

Zhang, Jian; Feng, Kai-Rui; Zheng, Ming-Yue; Cai, Yu-Dong

2013-01-01

436

Syntheses, Photochemical Properties, and Tautomerism of Intramolecularly Friedel-Crafts Acylated Hypericin Derivatives  

Microsoft Academic Search

Summary. Intramolecularly Friedel-Crafts acylation carried out on the hypericin moiety provided a new class of 9,12-dicarbonyl substituted hypericin derivatives as potential candidates for photodynamic therapy (PDT). Focusing on cyclopentanone and cyclohexanone condensed derivatives, investigations concerning the chemical and photochemical properties as well as the tautomerism of these compounds were performed.

Mario Waser; Yulita Popova; Christoph Etzlstorfer; Werner F. Huber; Heinz Falk

2005-01-01

437

Characterization of red mud derived from a combined Bayer Process and bauxite calcination method  

Microsoft Academic Search

Red mud can be derived from the processing of bauxite using different methods. The chemical and mineralogical composition of the combined Bayer Process and bauxite calcination red mud (BPBCRM) differs markedly from those of the pure Bayer Process red mud (PBPRM). In this study, red mud derived from a combined Bayer Process and bauxite calcination method was characterized. The results

Yong Liu; Chuxia Lin; Yonggui Wu

2007-01-01

438

Early diagenesis of plant-derived dissolved organic matter along a wetland, mangrove, estuary ecotone  

Microsoft Academic Search

We studied the role of photochemical and microbial processes in contributing to the transformation of dissolved organic matter (DOM) derived from various plants that dominate the Florida Everglades. Plant-derived DOM leach- ate samples were exposed to photochemical and microbial degradation and the optical, chemical, and molecular weight characteristics measured over time. Optical parameters such as the synchronous fluorescence intensity be-

Norman M. Scully; Nagamitsu Maie; Susan K. Dailey; Joseph N. Boyer; Ronald D. Jones; Rudolf Jaffé

2004-01-01

439

Field-derived Henry's law constants for polychlorinated biphenyls in oceanic waters  

Microsoft Academic Search

Accurate knowledge of Henry's law constants (Kaw) is very important for fate and transport studies of organic chemicals. Here field-derived Kaw values for polychlorinated biphenyl (PCB) congeners (PCBs 28, 49, 52, 118, 138, 149, and 153) were determined in the open Atlantic Ocean, at locations where air and seawater were assumed to be at equilibrium. Field-based Kaw values were derived

Rosalinda Gioia; Kevin C. Jones; Rainer Lohmann; Luca Nizzetto; Jordi Dachs

2010-01-01

440

Separations Needs for the Alternate Chemical Cycles  

SciTech Connect

The bulk of the efforts for the development of a hydrogen production plant supported by the Nuclear Hydrogen Initiative (NHI) have been directed towards the sulfur-iodine (S-I) thermochemical cycle. However, it was judged prudent to re-investigate alternate chemical cycles in light of new developments and technical accomplishments derived from the current S-I work. This work analyzes the available data for the promising alternate chemical cycles to provide an understanding of their inherent chemical separations needs. None of the cycles analyzed have separations that are potential “show stoppers”; although some of the indicated separations will be challenging to perform. The majority of the separations involve processes that are either more achievable or more developed

Frederick F. Stewart

2007-05-01

441

Derivative-Discontinuous Electroheat Control  

Microsoft Academic Search

In electroheat processes such as induction furnaces, arc furnaces, radiant furnaces, plasma torches, fluidized beds, etc., that are usually discontinuously controlled (because of the large power ratings involved) a great deal of confusion has existed as to the effect of derivative signals in the primary feedback loop. This has resulted in empirical design rules for the derivative feedback in controllers

Willim K. Roots; Malayappan Shridhar

1969-01-01

442

Study of dextrin-derived curing agent for waterborne epoxy adhesive  

Microsoft Academic Search

In this study, a water-soluble dextrin derivative was synthesized by reacting dextrin with trimellitic anhydride. The chemical structure of the dextrin-derived curing agent was confirmed by FT-IR and 1H NMR. The dextrin derivative contained free carboxylic acid groups and was used as curing agent for waterborne epoxy in wood bonding test. The adhesion of wood bonded by this waterborne epoxy

Xiaoqing Liu; Yi Wang; Yang Cao; Vikram Yadama; Ming Xian; Jinwen Zhang

2011-01-01

443

Overview of medically important antifungal azole derivatives.  

PubMed Central

Fungal infections are a major burden to the health and welfare of modern humans. They range from simply cosmetic, non-life-threatening skin infections to severe, systemic infections that may lead to significant debilitation or death. The selection of chemotherapeutic agents useful for the treatment of fungal infections is small. In this overview, a major chemical group with antifungal activity, the azole derivatives, is examined. Included are historical and state of the art information on the in vitro activity, experimental in vivo activity, mode of action, pharmacokinetics, clinical studies, and uses and adverse reactions of imidazoles currently marketed (clotrimazole, miconazole, econazole, ketoconazole, bifonazole, butoconazole, croconazole, fenticonazole, isoconazole, oxiconazole, sulconazole, and tioconazole) and under development (aliconazole and omoconazole), as well as triazoles currently marketed (terconazole) and under development (fluconazole, itraconazole, vibunazole, alteconazole, and ICI 195,739). PMID:3069196

Fromtling, R A

1988-01-01

444

Thiadiazole derivatives with nonlinear optical properties  

NASA Astrophysics Data System (ADS)

Several potentially conducting polymers, optically nonlinear polymers, and biomaterials contain heterocyclic structures. Reduction of the energy band gap of a conjugated polymer is a topic of considerable interest due to the possible elimination of doping in the preparation of highly conductive polymers. Control of the energy gap value of a polymer by molecular design could modify its optical, electronic and optoelectronic properties. Thiadiazoles and their derivatives are the structural basis of some of these polymeric materials. The results of the calculation of the HOMO-LUMO gap, the dipole moment and polarizability of thiadiazole oligomers in vacuo and in the presence of solvents are reported. The calculations are based on density functional theory using a specially tailored model chemistry. The potential utility of these materials for the development of chemical sensors is discussed.

Marquez-Lucero, Alfredo

2005-04-01

445

Novel Therapeutics: NSAIDs, Derivatives, and Phosphodiesterases  

PubMed Central

The chemopreventive efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) for colorectal cancer has been well documented. However, long-term use of NSAIDs is precluded owing to potentially fatal toxicities associated with their mechanism of action involving cyclooxygenase (COX) inhibition. But studies have shown that their anticancer activity may be due, in part, to an off-target effect. Cyclic guanosine monophosphate (cGMP) phosphodiesterases (PDEs), which are responsible for negative regulation of cGMP signaling, are an attractive COX-independent target. cGMP signaling is aberrantly suppressed in cancer cells and its activation appears to be sufficient to inhibit tumor cell growth. Chemically modifying sulindac has produced a series of new derivatives that lack COX-inhibitory activity but have improved cGMP PDE inhibitory activity. This approach is proving to be a promising strategy for the discovery of improved agents for the prevention and/or treatment of colorectal cancer. PMID:23459242

Tinsley, Heather N.; Piazza, Gary A.

2012-01-01

446

Isocorydine derivatives and their anticancer activities.  

PubMed

In order to improve the anticancer activity of isocorydine (ICD), ten isocorydine derivatives were prepared through chemical structure modifications, and their in vitro and in vivo activities were experimentally investigated. 8-Amino-isocorydine (8) and 6a,7-dihydrogen-isocorydione (10) could inhibit the growth of human lung (A549), gastric (SGC7901) and liver (HepG2) cancer cell lines in vitro. Isocorydione (2) could inhibit the tumor growth of murine sarcoma S180-bearing mice, and 8-acetamino-isocorydine (11), a pro-drug of 8-amino-isocorydine (8), which is instable in water solution at room temperature, had a good inhibitory effect on murine hepatoma H22-induced tumors. The results suggested that the isocorydine structural modifications at C-8 could significantly improve the biological activity of this alkaloid, indicating its suitability as a lead compound in the development of an effective anticancer agent. PMID:25120059

Zhong, Mei; Liu, Yanjuan; Liu, Junxi; Di, Duolong; Xu, Mengrou; Yang, Yaya; Li, Wenguang; Chen, Yali; Liu, Jinxia

2014-01-01

447

Great Lakes: Chemical Monitoring  

ERIC Educational Resources Information Center

The Tenth Great Lakes Regional Meeting of the American Chemical Society met to assess current Chemical Research activity in the Great Lakes Basin, and addressed to the various aspects of the theme, Chemistry of the Great Lakes. Research areas reviewed included watershed studies, atmospheric and aquatic studies, and sediment studies. (BT)

Delfino, Joseph J.

1976-01-01

448

Chemically pumped iodine laser  

Microsoft Academic Search

A chemically pumped iodine-atom laser is described based on electronic energy transfer to atomic iodine from chemically generated O2(1?). The total extracted power (10 W) is approximately 3% of the power contained in the O2(1?) flow.

R. J. Richardson; C. E. Wiswall

1979-01-01

449

Chemical carcinogens. Second edition  

SciTech Connect

This book looks at the latest research in chemical carcinogenic agents. To gain an understanding these agents and their importance in identifying the occupational and environmental causes of cancer. Included are studies in soots, tars, and oils; DNA interaction of reactive intermediates; mineral fiber carcinogenesis; carcinogens in foods and medicine; and laboratory chemicals as carcinogens.

Searle, C.E.

1984-01-01

450

Chemical Effects of Ultrasonics  

Microsoft Academic Search

The present work was undertaken with the purpose of considering why and how reaction takes place in an ultrasonic field, rather than studying the chemical kinetics of such reactions. Experimental evidence is presented which supports the conclusions that chemical processes brought about by ultrasonics require cavitation. Furthermore, the experiments were planned so as to show whether the reactions take place

Mary Evelyn Fitzgerald; Virginia Griffing; James Sullivan

1956-01-01

451

Chemical and Physical Changes  

NSDL National Science Digital Library

The phenomenon is a chemical reaction between sugar and sulfuric acid. The demonstration (a discrepant event) compares the way sugar and water interact when combined (physical change) to the way sugar and sulfuric acid interact when combined (chemical change). In part II, students are given additional substances and changes to observe.

452

Chemical Biology Consortium Agreement  

Cancer.gov

NCI_CBC v.1.2 9/2009 The National Cancer Institute’s Chemical Biology Consortium Participants Agreement Mission: The mission of the National Cancer Institute’s (“NCI”) Chemical Biology Consortium (“CBC”) is to increase the flow of early

453

Chemical Process Synthesis.  

ERIC Educational Resources Information Center

Process synthesis is the specification of chemical and physical operations and the selection and interconnection of equipment to implement these operations to effect desired chemical processing transformations. Optimization and evolutionary and systematic generation process synthesis approaches are described. (Author/SK)

Siirola, J. J.

1982-01-01

454

Geothermal chemical engineering  

Microsoft Academic Search

Programs, projects, and research for utilization of geothermal energy are reviewed from a chemical engineering vantage point, with attention given to costs, proved resources, reservoir models, applications, and environmental impact. Neglect of crucial chemical reactions occurring in geothermal systems impair the usefulness of existing models constructed for hydrothermal reservoirs. Currently entertained models, studies of reservoir mechanics and ground water hydrology,

R. C. Axtmann; L. B. Peck

1976-01-01

455

Chemical Kinetics: Isolation Method  

NSDL National Science Digital Library

This site offers an interactive tutorial that guides the student through the Method of Isolation used for the determination of chemical reaction rate laws and rate constants. This tutorial is coupled to others to further guide the student to a better understanding of chemical kinetics.

Blauch, David N.

456

Forward chemical genetic screening.  

PubMed

Chemical genetics utilizes small molecules to perturb biological processes. Unlike conventional genetics methods, which involve the alteration of genetic information mostly with lasting effects, chemical genetics allows temporary and reversible alterations of biological processes. Furthermore, it enables the alteration of biological processes in a dose-dependent manner, providing an advantage over conventional genetics. In the present chapter, the general procedures of forward chemical genetic screening are described. Forward chemical genetic screening can be performed in three steps. The first step involves the identification of small molecules that induce phenotypic or physiological changes in a biological system from a chemical library. In the second step, cellular targets that interact with the isolated chemical, which are mostly proteins, are identified. Although several methods can be applied in the second step, the most common one is affinity pull-down assay using a target protein that binds to the isolated compound. However, affinity pull-down of a target protein is a formidable barrier in forward chemical genetics. We introduced a tagged chemical library approach that significantly facilitates the identification of target proteins. The third step consists of the validation of the target protein, which should include the assessment of target specificity. This step is critical because small molecules often show pleiotropic effects due to low specificity. The specificity test may include a competition assay using cold competitors and a genetic study using mutants or transgenic lines modified for the cellular target. PMID:24057378

Choi, Hyunmo; Kim, Jun-Young; Chang, Young Tae; Nam, Hong Gil

2014-01-01