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1

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

PubMed Central

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

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

2014-01-01

2

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.

Pollak, Michael

2013-01-01

3

Insulin and longevity: antidiabetic biguanides as geroprotectors  

Microsoft Academic Search

The results of previous experimental studies of effects of antidiabetic biguanides (phenformin and buformin) on life span\\u000a and spontaneous tumor incidence in mice and rats were recalculated and reanalyzed using standard demographic models of mortality.\\u000a The chronic treatment of female C3H\\/Sn mice with phenformin prolonged the mean life span by 21.1% (P < 0.05), the mean life span of the

Vladimir N. Anisimov; Anna V. Semenchenko; Anatoli I. Yashin

2003-01-01

4

Biguanide related compounds in traditional antidiabetic functional foods.  

PubMed

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

Perla, Venu; Jayanty, Sastry S

2013-06-01

5

Structural Requirements of Guanide, Biguanide, and Bisbiguanide Agents for Antiplaque Activity  

PubMed Central

The bactericidal efficacy of 16 guanide, biguanide, and bisbiguanide agents was studied in vitro against intact preformed plaques of four oral (plaque-forming) microorganisms: Streptococcus mutans, S. sanguis, Actinomyces viscosus, and A. naeslundii. The activities of these agents were examined in relation to their molecular configurations. These studies indicated that the bis- and biguanide configurations are important for efficacy, as is the length of the alkyl side chain. No structural moiety determined efficacy by itself. Furthermore, the activities of these agents were studied to determine the minimal conditions (concentration, duration, and frequency) of treatment required for likely clinical efficacy. At least six agents were judged to have equal or greater efficacy than the reference agent, chlorhexidine digluconate. A plaque bactericidal index was derived for the most potent agents, and comparison to the bactericidal properties of chlorhexidine was expressed as a chlorhexidine coefficient.

Tanzer, J. M.; Slee, A. M.; Kamay, B. A.

1977-01-01

6

Practical Chemical Sensors from Chemically Derived Graphene  

Microsoft Academic Search

We report the development of useful chemical sensors from chemically converted graphene dispersions using spin coating to create single-layer films on interdigitated electrode arrays. Dispersions of graphene in anhydrous hydrazine are formed from graphite oxide. Preliminary results are presented on the detection of NO2,NH3, and 2,4-dinitrotoluene using this simple and scalable fabrication method for practical devices. Currentversusvoltage curves are linear

Jesse D. Fowler; Matthew J. Allen; Vincent C. Tung; Yang Yang; Richard B. Kaner; Bruce H. Weiller

2009-01-01

7

Alteration of bile acid metabolism and vitamin-B 12 -absorption in diabetics on biguanides  

Microsoft Academic Search

Summary  Since vitamin B12malabsorption has been described in diabetics on biguanides and inhibition of bile acid absorption found in rat ileum the effect of treatment with different biguanides (phenformin, buformin, metformin) on bile acid metabolism and vitamin B12 absorption was assessed in maturity onset diabetics. Biguanides did not alter faecal weight or faecal fat excretion, but they decreased faecal bile acid

W. F. Caspary; I. Zavada; W. Reimold; U. Deuticke; D. Emrich; B. Willms

1977-01-01

8

Erythropoietin Derived by Chemical Synthesis  

PubMed Central

Erythropoietin is a signaling glycoprotein that controls the fundamental process of erythropoiesis, orchestrating the production and maintenance of red blood cells. As administrated clinically, erythropoietin has a polypeptide backbone with complex dishomogeneity in its carbohydrate domains. Here we describe the total synthesis of homogeneous erythropoietin with consensus carbohydrate domains incorporated at all of the native glycosylation sites. The oligosaccharide sectors were built by total synthesis and attached stereospecifically to peptidyl fragments of the wild-type primary sequence, themselves obtained by solid-phase peptide synthesis. The glycopeptidyl constructs were joined by chemical ligation, followed by metal-free dethiylation, and subsequently folded. This homogeneous erythropoietin glycosylated at the three wild-type aspartates with N-linked high-mannose sialic acid–containing oligosaccharides and O-linked glycophorin exhibits Procrit-level in vivo activity in mice.

Shieh, Jae-Hung; Peguero, Elizabeth; Hendrickson, Ronald; Moore, Malcolm A. S.; Danishefsky, Samuel J.

2014-01-01

9

Chemically Derived, Ultrasmooth Graphene Nanoribbon Semiconductors  

Microsoft Academic Search

We developed a chemical route to produce graphene nanoribbons (GNR) with width below 10 nanometers, as well as single ribbons with varying widths along their lengths or containing lattice-defined graphene junctions for potential molecular electronics. The GNRs were solution-phase derived, stably suspended in solvents with noncovalent polymer functionalization, and exhibited ultrasmooth edges with possibly well-defined zigzag or armchair-edge structures. Electrical

Xiaolin Li; Xinran Wang; Li Zhang; Sangwon Lee; Hongjie Dai

2008-01-01

10

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

11

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.

Ferrari, Giulio; Matuska, Stanislav; Rama, Paolo

2011-01-01

12

Chemically derived, ultrasmooth graphene nanoribbon semiconductors.  

PubMed

We developed a chemical route to produce graphene nanoribbons (GNR) with width below 10 nanometers, as well as single ribbons with varying widths along their lengths or containing lattice-defined graphene junctions for potential molecular electronics. The GNRs were solution-phase-derived, stably suspended in solvents with noncovalent polymer functionalization, and exhibited ultrasmooth edges with possibly well-defined zigzag or armchair-edge structures. Electrical transport experiments showed that, unlike single-walled carbon nanotubes, all of the sub-10-nanometer GNRs produced were semiconductors and afforded graphene field effect transistors with on-off ratios of about 10(7) at room temperature. PMID:18218865

Li, Xiaolin; Wang, Xinran; Zhang, Li; Lee, Sangwon; Dai, Hongjie

2008-02-29

13

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

PubMed

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

14

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.

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

2013-01-01

15

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

Microsoft Academic Search

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

Mario I. Ortiz

2011-01-01

16

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

PubMed

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

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

2011-06-01

17

Sulphonylureas and biguanides do not affect insulin binding in H35 hepatoma cells.  

PubMed

Six sulphonylureas (tolbutamide, tolazamide, chlorpropamide, glibornuride, glipizide and gliquidone) and 2 biguanides (metformin and buformin) were tested for possible effects on insulin binding to H 35 rat hepatoma cells in culture. Insulin binding was measured after 24 and 72 hr of culturing cells in medium containing the drugs. Buformin and gliquidone were tested in concentrations from 10(-8)-5 X 10(-5) M, the other drugs in concentrations from 10(-7)-5 X 10(-4) M. All 24-hr experiments were repeated in cells down-regulated with 10 micrograms/ml insulin. None of the oral hypoglycemic agents tested had any significant influence on insulin binding to H 35 hepatoma cells, either in the presence or absence of insulin. We suggest that the insulin receptor status, at least in this type of liver cell, is not influenced by sulphonylureas or biguanides. PMID:3757414

De Vries, C P; van der Veen, E A

1986-07-01

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

New polymeric biocides: synthesis and antibacterial activities of polycations with pendant biguanide groups.  

PubMed

Acrylate monomers with pendant biguanide groups were successfully synthesized, and their homopolymers and copolymers were prepared with acrylamide. These cationic disinfectants of polymeric forms exhibited high antibacterial activity against gram-positive bacteria, whereas they were less active against gram-negative bacteria. It was found that the activity of the polymeric disinfectants was much higher than that of the monomeric species, and the difference in activity between the polymers and the monomers was discussed on the basis of their contributions to each elementary process of the lethal action. PMID:6385836

Ikeda, T; Yamaguchi, H; Tazuke, S

1984-08-01

20

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

21

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

22

Metabolic determinants of cancer cell sensitivity to glucose limitation and biguanides  

NASA Astrophysics Data System (ADS)

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.

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

23

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

24

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

NASA Astrophysics Data System (ADS)

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

Yamamoto, Hiroki; Kudo, Hiroto; Kozawa, Takahiro

2014-03-01

25

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.

Sotiropoulos, Vassilios; Kaznessis, Yiannis N.

2011-01-01

26

Does atorvastatin work more effectively than biguanides in reducing cardiovascular risk factors?  

PubMed Central

Increased risk of coronary artery disease in diabetic persons is associated with increased level of lipoproteins. Usually, such risks are reverted with glycemic control by antidiabetic medicines in Type I diabetes millitus. However, in Type II diabetes mellitus lipid values can be improved using antidiabetics but still the risk of coronary artery disease remains. The initial approach for reducing lipid contents in diabetic patients should include glycemic control, diet, weight loss, and exercise. But if it fails then lipid-lowering agents like fibrate and HMG CoA reductase (3-hydroxy-3-methyl-glutaryl-CoA reductase) inhibitors should work effectively. In the present study results of atorvastatin compared with biguanides proved atorvastatin as a more effective lipid-lowering agent along with antidiabetic activity so it can effectively help in reducing the risk of cardiovascular disease (CVD).

Siddiq, Afshan; Khan, Rafeeq Alam; Baig, Sadia Ghousia

2011-01-01

27

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

28

Physico-chemical characterization of sesame oil derivatives.  

PubMed

Ozone treatment of commercially available vegetable oils gives rise to the formation of chemical species that are responsible for the therapeutic properties of ozonated oil derivatives in dermatological diseases. In the last years, these products have been successfully used as a topical disinfectant in a number of serious skin affections. The medical application of empirically prepared ozonated oil has yielded striking improvements with unexpected and rapid healing, compelling us to begin a long-range study aiming first to define the main characteristics of the most common ozonated vegetable oils, about which there is usually no medical consensus because of the lack of standardization of their technological parameters. Sesame oil was selected because of its great amount of polyunsaturated acyl groups, as well as natural antioxidants. Moreover, we have determined the kinetics and optimal conditions of ozonation (e.g., ozone concentrations, time of exposure, temperature) for obtaining an ozonated oil characterized by well-established technological and physico-chemical properties, namely an accurate peroxide value determination. On the basis of the results, we have gained an understanding of the modifications of the vegetable oils during the ozonation process. PMID:18679737

Zanardi, Iacopo; Travagli, Valter; Gabbrielli, Alessandro; Chiasserini, Luisa; Bocci, Velio

2008-09-01

29

Biguanide-, imine-, and guanidine- based networks as catalysts for transesterification of vegetable oil  

PubMed Central

Polycationic systems based on poly(hexamethylene biguanide) (PHMBG), branched polyethyleneimine (PEI) and poly(N-vinylguanidine) (PVG) have been evaluated as heterogeneous catalysts for the transesterification of sunflower oil by methanol. Insoluble networks are synthesized via crosslinking of PHMBG by either 4,4?-methylenebis(N,N-diglycidylaniline) or polyisocyanate prepolymer, PEI with sebacoyl chloride, and PVG with 1,4-butanediol diglycidyl ether. PHMBG and its crosslinked networks appeared to be remarkably efficient catalysts, enabling 80–100% triglyceride conversion within 0.5 h at 70°C. PEI-based networks catalyzed triglyceride transesterification with rates 8- to 12-fold slower than their PHMBG-based counterparts. The PVG-based networks, which were devoid of hydrophobic moieties, appeared to be inefficient catalysts due to limited accessibility of the basic guanidine groups to reactants. The PHMBG networks were shown to be recyclable by a simple centrifugal filtration. After 15 cycles of recovery and reuse, only 10–15% decline in performance was observed.

Bromberg, Lev; Fasoli, Ezio; Alvarez, Michael; Hatton, T. Alan; Barletta, Gabriel L.

2010-01-01

30

Scedosporium prolificans Osteomyelitis in an Immunocompetent Child Treated with Voriconazole and Caspofungin, as Well as Locally Applied Polyhexamethylene Biguanide  

PubMed Central

Scedosporium species are increasingly isolated from immunocompromised and immunocompetent patients. Unfortunately, Scedosporium infections are generally resistant to amphotericin B, and Scedosporium prolificans strains are particularly resistant to the antifungal agents now in use. We report here on an immunocompetent child with S. prolificans-associated osteomyelitis successfully treated with debridement, local irrigation with polyhexamethylene biguanide, and the systemic administration of voriconazole and caspofungin despite poor in vitro activity of voriconazole alone against the isolate. We also review the treatments and outcomes of 28 reported cases of osteomyelitis or septic arthritis caused by Scedosporium species in immunocompetent patients.

Steinbach, William J.; Schell, Wiley A.; Miller, Jackie L.; Perfect, John R.

2003-01-01

31

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

PubMed Central

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

Lebedev, A V; Rezvukhin, A I

1984-01-01

32

Permissible Concentrations of Chemicals in Air and Water Derived from RTECS Entries.  

National Technical Information Service (NTIS)

Many chemicals are of concern to human health, but only a few have epidemiologically derived risk estimates. About 45,000 chemicals are listed in the Registry of Toxic Effects of Chemical Substances (RTECS), most of which have had some testing in subhuman...

T. D. Jones P. J. Walsh E. A. Zeighami

1984-01-01

33

Tomato derived polysaccharides for biotechnological applications: chemical and biological approaches.  

PubMed

Recent studies concerning the isolation and purification of exopolysaccharides from suspension-cultured tomato (Lycopersicon esculentum L. var. San Marzano) cells and the description of a simple, rapid and low environmental impact method with for obtaining polysaccharides from solid tomato-processing industry wastes are reported. Their chemical composition, rheological properties and partial primary structure were determined on the basis of spectroscopic analyses (UV, IR, GC-MS, (1)H-, (13)C-NMR). Moreover, the anticytotoxic activities of exopolysaccharides obtained from cultured tomato cells were tested in a brine shrimp bioassay and the preparation of biodegradable film by chemical processing of polysaccharides from solid tomato industry waste was also reported. PMID:18596664

Tommonaro, Giuseppina; Poli, Annarita; De Rosa, Salvatore; Nicolaus, Barbara

2008-01-01

34

Chemical Synthesis of U1 snRNA Derivatives  

PubMed Central

U1 snRNA is an interesting biological tool for splicing correction and regulation of gene expression. However, U1 snRNA has never been chemically synthesized. In this study, the first chemical synthesis of U1snRNA and its analogues was carried out. Moreover, it was found that the binding affinity of the modified U1 snRNA with an ethylene glycol linkage to snurportin 1 (nuclear import adaptor) was as high as that of the unmodified RNA.

2013-01-01

35

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.

Lennen, Rebecca M; Pfleger, Brian F

2013-01-01

36

Quantum chemical study on nitroimidazole, polynitroimidazole and their methyl derivatives.  

PubMed

The insensitive explosive candidates, nitroimidazoles, polynitroimidazoles and their methyl derivatives, are investigated using density functional theory (DFT). The homolytic bond dissociation energies (BDEs) corresponding to -NO2 group removal from carbon or nitrogen site on imidazole ring were calculated at B3P86/6-311G** level, and the weakest bond has been determined. Further, a correlation is developed between impact sensitivity h50 and the ratio (BDE/E) of the weakest bond BDE to the total energy E, and we extrapolate this relationship to predict the impact sensitivities for compounds where experiments are not available. It is found that most of the title compounds are insensitive towards impact stimuli with their h50 larger than 60.0cm. Heats of formation (HOFs) for the 21 title compounds at 298K in gas are also determined both at B3LYP/6-311G** and B3P86/6-311G** levels using isodesmic work reactions. The calculated BDEs and HOFs consistently indicate that C-nitro-substituted imdazole is more stable than the corresponding N-substituted one, and the introduction of methyl on C increases the stability whereas the methyl attached to N atom decreases the stability. PMID:18486326

Su, Xinfang; Cheng, Xinlu; Meng, Chuanmin; Yuan, Xiaoli

2009-01-15

37

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

NASA Technical Reports Server (NTRS)

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

1976-01-01

38

Effect of bed time intermediate acting insulin in NIDDM subjects refractory to a combination of sulphonylureas and biguanides.  

PubMed

The effect of a single dose of intermediate acting (Lente) insulin given subcutaneously at 9.00 P.M. in 22 NIDDM subjects refractory to a combination of Sulphonylureas and Biguanides was analysed. Euglycemia was achieved and maintained during the study period of three months with a mean insulin requirement of 14.22 +/- 5.98 units/day. Plasma FFA, Total cholesterol, triglyceride and VLDL-cholesterol also showed significant reduction. The level of FFA modulates hepatic glucose production, which in turn correlates positively with the fasting blood glucose. The therapeutic modality of bed time Lente Insulin based on physiological principles is an effective way of achieving glycemic control in NIDDM subjects who have become non-responsive to oral hypoglycemic agents. PMID:1307353

Seshiah, V; Shanker, R; Madhavan, R; Venkataraman, S; Sundaram, A; Seshasaianam, C; Sankaran, J R

1992-10-01

39

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

40

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

Microsoft Academic Search

As a class, the biguanides induce lactic acidosis, a hallmark of mitochondrial impairment. To assess potential mitochondrial impairment, we evaluated the effects of metformin, buformin and phenformin on: 1) viability of HepG2 cells grown in galactose, 2) respiration by isolated mitochondria, 3) metabolic poise of HepG2 and primary human hepatocytes, 4) activities of immunocaptured respiratory complexes, and 5) mitochondrial membrane

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

2008-01-01

41

Chemical and rheological characterizations of some vegetable oils derivatives commonly used in printing inks  

Microsoft Academic Search

This study concerns the characterization of vegetable oils and some of their derivatives which are commonly used in offset printing ink formulations. Chemical and rheological characterizations were performed in order to gain a better insight into their structure\\/properties relationships. The aim of this study was therefore to improve the quality and performance of printing inks on the basis of sound

Anne Blayo; Alessandro Gandini; Jean-François Le Nest

2001-01-01

42

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

43

Chemical Derivatives and Elemental Transport Coefficients in Plasma Flows Near Local Equilibrium  

SciTech Connect

Elemental transport coefficients are extensively used for modeling chemically reacting and plasma flows when the proximity to local equilibrium is exploited to combine the ordinary transport coefficients into a few elemental coefficients. A deeper insight into the physics of chemically reacting flows near local equilibrium can be achieved by looking only at a reduced number of relevant parameters in the expression of the flow transport properties.A new technique to calculate chemical derivatives using an analytical method which strongly reduces computational effort and numerical errors is introduced. A general formalism for elemental diffusion velocities, heat flux and electric current for plasma flows near local equilibrium is then derived. An order of magnitude analysis shows how to identify the main contributions to the transport fluxes among: elemental fractions gradients, pressure or temperature gradients, electric field. The resulting theoretical framework is particularly suitable for numerical implementation.The present contribution aims to provide a summary of the theoretical framework described above. Numerical examples of chemical derivatives and elemental transport coefficients are given. Results are presented for a carbon dioxide mixture of practical interest for aerospace applications and atmospheric entry problems.

Orsini, Alessio [Avio Aerospace Propulsion, via I Maggio 99, 10040 Rivalta di Torino (Italy); Kustova, Elena V. [Saint Petersburg State University, Department of Mathematics and Mechanics, 198504, Universitetsky pr. 28, Saint Petersburg (Russian Federation)

2011-05-20

44

Prediction of Henry's law constants of triazine derived herbicides from quantum chemical continuum solvation models.  

PubMed

The Henry's law constants (H) for triazine derived herbicides are calculated using quantum chemical solvation models, SM2, SM3, PCM-DFT, and CPCM-DFT, and their performances are discussed. The results show considerable differences in performance among the different levels of theory. The values of H calculated by the semiempirical methods agree much better with the experimental values than those obtained at the DFT level. The differences are discussed in terms of the different contributions, electrostatic and no-electrostatic, to Gibbs free energy of solvation. In addition, the Henry's law constants of some triazine derived herbicides whose values have not been reported earlier are predicted as well. PMID:12870915

Delgado, Eduardo J; Alderete, Joel B

2003-01-01

45

Effects of Hemoglobin Variants and Chemically Modified Derivatives on Assays for Glycohemoglobin  

Microsoft Academic Search

Background: Glycohemoglobin (gHb), measured as he- moglobin (Hb) A1c or as total gHb, provides a common means for assessing long-term glycemic control in indi- viduals with diabetes mellitus. Genetic variants and chemically modified derivatives of Hb can profoundly affect the accuracy of these measurements, although effects vary considerably among commercially available methods. The prevalence of genetic variants such as HbS,

Lynn Bry; Philip C. Chen; David B. Sacks

2001-01-01

46

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

PubMed Central

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.

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

2012-01-01

47

A new non-invasive approach based on polyhexamethylene biguanide increases the regression rate of HPV infection  

PubMed Central

Background HPV infection is a worldwide problem strictly linked to the development of cervical cancer. Persistence of the infection is one of the main factors responsible for the invasive progression and women diagnosed with intraepithelial squamous lesions are referred for further assessment and surgical treatments which are prone to complications. Despite this, there are several reports on the spontaneous regression of the infection. This study was carried out to evaluate the effectiveness of a long term polyhexamethylene biguanide (PHMB)-based local treatment in improving the viral clearance, reducing the time exposure to the infection and avoiding the complications associated with the invasive treatments currently available. Method 100 women diagnosed with HPV infection were randomly assigned to receive six months of treatment with a PHMB-based gynecological solution (Monogin®, Lo.Li. Pharma, Rome - Italy) or to remain untreated for the same period of time. Results A greater number of patients, who received the treatment were cleared of the infection at the two time points of the study (three and six months) compared to that of the control group. A significant difference in the regression rate (90% Monogin group vs 70% control group) was observed at the end of the study highlighting the time-dependent ability of PHMB to interact with the infection progression. Conclusions The topic treatment with PHMB is a preliminary safe and promising approach for patients with detected HPV infection increasing the chance of clearance and avoiding the use of invasive treatments when not strictly necessary. Trial registration ClinicalTrials.gov Identifier NCT01571141

2012-01-01

48

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

SciTech Connect

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

Dykens, James A. [Drug Safety Research and Development, Pfizer, Inc., Ramsgate Rd. Sandwich, CT13 9NJ (United Kingdom)], E-mail: jamesdykens@pfizer.com; Jamieson, Joseph; Marroquin, Lisa [Drug Safety Research and Development, Pfizer, Inc., 10646 Science Center Drive, San Diego, CA 92121 (United States); Nadanaciva, Sashi; Billis, Puja A.; Will, Yvonne [Exploratory Safety Differentiation, Pfizer, Inc. Eastern Point Rd, Groton CT, 06340 (United States)

2008-12-01

49

Thermal Emission Spectrometer Derived Chemical Abundances of Low-Albedo Surfaces on Mars  

NASA Astrophysics Data System (ADS)

The mineralogical and chemical properties of the dust, soil, and rocks that comprise the martian regolith are a reflection of the igneous and sedimentary processes that create and modify these materials. TES derived mineral abundances have been used to constrain the bulk composition of the martian surface and provide insight to the degree of differentiation of the martian crust and mantle and the nature of surface-atmosphere interactions. TES is primarily a mineralogical tool, but it can also provide a means of estimating chemistry. Bulk rock geochemistry can be accurately calculated from deconvolved modal mineralogies by combining the compositions (wt.% oxides) of the spectral end-members in proportion to their relative modeled abundances. Derived chemical abundances from thermal emission spectra are thus a recasting of rock compositions into a form which complements modeled mineral abundances. In studies of terrestrial volcanic rocks at both laboratory (2 cm-1) and TES (10 cm-1) spectral samplings, the one-? standard deviations of the absolute differences between measured and modeled major oxide abundances (SiO2, Na2O, K2O, CaO, MgO, FeO, Al2O3) range from 0.4 to 2.6 wt %. Derived chemistries have been used to accurately classify volcanic compositions and demonstrate the feasibility of using similar techniques for the interpretation of terrestrial laboratory samples and TES-resolution data. In this study, we report initial global major oxide abundance maps (4 pixels/degree or 15 km/pixel) of low-albedo materials to be used with existing global mineral abundance maps for accurately classifying martian surface compositions. Volcanic rocks are commonly assigned petrologic names by their chemical compositions because their modal mineralogies, even when quantified, are not always diagnostic. TES derived major oxide abundance maps can also serve for comparison to 2001 Mars Odyssey Gamma Ray Spectrometer derived element abundance maps (.1 pixels/degree or 600 km/pixel). Examining both mineralogical and chemical relationships over spatial and temporal scales will provide additional insight to better understand the relative roles of igneous and sedimentary processes on Mars.

Wyatt, M. B.; Bandfield, J. L.; McSween, H. Y.; Christensen, P. R.

2003-12-01

50

Chemically defined conditions for human iPS cell derivation and culture  

PubMed Central

We reexamine the individual components for human ES and iPS cell culture, and formulate a cell culture system in which all protein reagents for liquid media, attachment surfaces, and splitting are chemically defined. A major improvement is the lack of a serum albumin component, as variations in either animal or human sourced albumin batches have previously plagued human ES and iPS cell culture with inconsistencies. Using this new medium (E8) and vitronectin-coated surfaces, we demonstrate improved derivation efficiencies of vector-free human iPS cells with an episomal approach. This simplified E8 medium should facilitate both the research use and clinical applications of human ES and iPS cells and their derivatives, and should be applicable to other reprogramming methods.

Chen, Guokai; Gulbranson, Daniel R.; Hou, Zhonggang; Bolin, Jennifer M.; Ruotti, Victor; Probasco, Mitchell D.; Smuga-Otto, Kimberly; Howden, Sara E.; Diol, Nicole R.; Propson, Nicholas E.; Wagner, Ryan; Lee, Garrett O.; Antosiewicz-Bourget, Jessica; Teng, Joyce M. C.; Thomson, James A.

2011-01-01

51

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

52

LOAD TRANSFER AND MECHANICAL PROPERTIES OF CHEMICALLY DERIVED SINGLE LAYER GRAPHENE REINFORCEMENTS IN POLYMER COMPOSITES  

PubMed Central

We report load transfer and mechanical properties of chemically derived single layer graphene (SLG) as reinforcements in poly (dimethyl) siloxane (PDMS) composites. Mixing single layer graphene in polymers resulted in the marked decrease of the G’ or 2D band intensity due to doping and functionalization. A Raman G mode shift of 11.2 cm?1/% strain in compression and 4.2 cm?1/% strain in tension is reported. An increase in elastic modulus of PDMS by ~42%, toughness by ~39%, damping capability by ~673%, and strain energy density of ~43% by the addition of 1 wt. % SLG in PDMS is reported.

Xu, Peng; Loomis, James; Panchapakesan, Balaji

2013-01-01

53

Derivation of the chemical-equilibrium rate coefficient using scattering theory  

NASA Technical Reports Server (NTRS)

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

Mickens, R. E.

1977-01-01

54

Chemically sulfated Escherichia coli K5 polysaccharide derivatives as extracellular HIV1 Tat protein antagonists  

Microsoft Academic Search

The HIV-1 transactivating factor (Tat) acts as an extracellular cytokine on target cells, including endothelium. Here, we report about the Tat-antagonist capacity of chemically sulfated derivatives of the Escherichia coli K5 polysaccharide. O-sulfated K5 with high sulfation degree (K5-OS(H)) and N,O-sulfated K5 with high (K5-N,OS(H)) or low (K5-N,OS(L)) sulfation degree, but not unmodified K5, N-sulfated K5, and O-sulfated K5 with

Chiara Urbinati; Antonella Bugatti; Pasqua Oreste; Giorgio Zoppetti; Johannes Waltenberger; Stefania Mitola; Domenico Ribatti; Marco Presta; Marco Rusnati

2004-01-01

55

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

PubMed

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

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

2013-04-15

56

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

57

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

58

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

59

[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

60

Heteroepitaxial Growth of Chemically Derived BARIUM(2) Yttrium COPPER(3) OXIDE(7-X) Thin Films  

NASA Astrophysics Data System (ADS)

Nucleation of the epitaxial BYC was studied by cross-section TEM characterization of films deposited on artificially stepped (001) LaAlO_3 substrates. The steps were found to act as preferred sites for nucleation of 90^circ -misoriented grains in the chemically derived BYC thin films. Comparison with the microstructures of films prepared by in situ pulsed laser deposition on the same substrates indicate the growth rate:nucleation rate ratio was higher in the chemically derived films. Large native steps may form on nominally flat (001) LaAlO_3 due to shear strain associated with the rhombohedral to cubic phase transformation that occurs in this crystal a ~ 450^circC. These native steps appeared to be responsible for the misoriented (c -axis in-plane) BYC grains observed in the films. The BYC nucleated heterogeneously on the substrate surface between 720 and 770^circC during rapid heating to the annealing temperature of 830 ^circC. The epitaxial film grew from a polycrystalline intermediate that consisted of 20-50 nm diameter Cu- and Y-rich particles and a Ba -rich nanocrystalline phase. The BYC crystallites with c-axis normal to the film plane coalesced early on in the transformation process, and grew more slowly upward into the overlying polycrystalline material. Epitaxial growth and densification may have been assisted by the transient presence of a liquid phase early in the growth heat treatment. Thermal analysis of the intermediate material detected evidence of partial melting at ~715 ^circC, under the same P(O _2) conditions used in the furnace heat treatments. Cross-sectional TEM examination of chemically derived films of ~80 nm nominal thickness indicates the films are faulted, with numerous polytypoidal stacking faults and anti-phase boundaries. The stacking fault density was found to decrease with increasing distance above the film/substrate interface in several thicker films. The transport J_{rm c} (H_{app} = 0, T = 77 K) of films annealed at 830 ^circC in a 250 ppm oxygen atmosphere fell from >5 MA/cm^2 to ~1 MA/cm^2 as the film thickness was increased from ~ 80 nm to ~500 nm. These observations suggest that extended microstructural defects in the BYC films may play a larger role in flux vortex pinning at low magnetic induction than is commonly recognized. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253 -1690.) (Abstract shortened by UMI.).

McIntyre, Paul Cameron

61

Diamagnetic Anisotropy Derived from Single Chemical Bonds in the Silicate Tetrahedral Networks  

NASA Astrophysics Data System (ADS)

The diamagnetic anisotropy (??)DIA derived from the individual bonding orbitals of the silicate [TO4] networks is estimated from the observed results on ?-quartz [SiO2], orthoclase [KAlSi3O8] and apophyllite [Ca4KF(Si4O10)2, 8H2O]. The (??)DIA value of individual chemical bond was estimated to be -3.5×10-30 emu/mol, the uniaxial principal axis being parallel to the bond direction. The calculated results indicate that the bond direction is the magnetically unstable axis. This result is compatible with the observed and calculated distributions of electron density for the T O orbitals, which are preferentially spread in the direction off the bond direction.

Uyeda, Chiaki; Ohtawa, Kouichi; Okita, Kazuyuki; Uyeda, Natsu

2001-03-01

62

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

63

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

PubMed

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

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

2014-07-01

64

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

65

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

PubMed

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

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

2014-07-01

66

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

67

Cervicovaginal safety of the formulated, biguanide-based human immunodeficiency virus type 1 (HIV-1) inhibitor NB325 in a murine model.  

PubMed

Vaginal microbicides that reduce or eliminate the risk of HIV-1 sexual transmission must do so safely without adversely affecting the integrity of the cervicovaginal epithelium. The present studies were performed to assess the safety of the biguanide-based antiviral compound NB325 in a formulation suitable for topical application. Experiments were performed using a mouse model of cervicovaginal microbicide application, which was previously shown to be predictive of topical agent toxicity revealed in microbicide clinical trials. Mice were exposed vaginally to unformulated NB325 or NB325 formulated in the hydroxyethyl cellulose "universal placebo." Following exposures to formulated 1% NB325 for 10 min to 24?h, the vaginal and cervical epithelia were generally intact, although some areas of minimal vaginal epithelial damage were noted. Although formulated NB325 appeared generally safe for application in these studies, the low but observable level of toxicity suggests the need for improvements in the compound and/or formulation. PMID:22131821

Lozenski, Karissa; Kish-Catalone, Tina; Pirrone, Vanessa; Rando, Robert F; Labib, Mohamed; Wigdahl, Brian; Krebs, Fred C

2011-01-01

68

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

PubMed Central

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

2013-01-01

69

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

PubMed Central

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

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

2006-01-01

70

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

71

Chemically stable N-methyl-4-(alkylthio)cyclophosphamide derivatives as prodrugs of 4-hydroxycyclophosphamide.  

PubMed

Two prototype N-methyl-4-thio-substituted cyclophosphamide (CP) derivatives (5 and 6), prodrugs of 4-hydroxycyclophosphamide (4-HO-CP), were designed to undergo oxidative N-demethylation to release the active alkylating agent. These prodrugs were chemically stable until oxidatively N-demethylated in the presence of hepatic microsomal P-450 enzymes. While the metabolism of 5 was enhanced in the presence of phenobarbital-induced microsomes, 6 was unaffected. Compound 6 was more active than 5 against L1210 leukemia cells grown in mice and exhibited statistically significant activity against the small cell lung cancer panel in the National Cancer Institute anticancer drug screen. Compound 5, like CP (1), was inactive in this screen. Thus, placement of a dithioester at the 4-position of N-methyl-HO-CP as in 6 markedly changes its spectrum of activity and has resulted in a new type of CP-based prodrug with antitumor activity against small cell lung cancer as well as leukemia cells in vitro as shown by their ability to inhibit tumor cell growth at concentrations as low as 10(-6) M. PMID:7877150

Moon, K Y; Shirota, F N; Baturay, N; Kwon, C H

1995-03-01

72

Improving surface functional properties of tofu whey-derived peptides by chemical modification with fatty acids.  

PubMed

Effect of acylation with saturated fatty acids on surface functional properties of tofu whey-derived peptides was investigated. Tofu whey (TW) and soy proteins (7S, 11S, and acid-precipitated soy protein [APP]) were hydrolyzed by Protease M 'Amano' G, and resulting peptide mixtures were acylated with esterified fatty acids of different chain length (6C to 18C) to form a covalent linkage between the carboxyl group of fatty acid and the free amino groups of peptide. Acylation significantly (P < 0.05) increased emulsifying properties of 7S, 11S, and APP peptides independent of fatty acid chain length. Acylation decreased water binding capacity although oil binding capacity of acylated tofu whey ultra filtered fraction (UFTW < 3 kDa), 7S- and 11S-peptides were improved compared to native peptides. 7S peptides acylated with long chain fatty acids had shown significant higher surface hydrophobicity as in contrast with acylated UFTW < 3 kDa and APP peptides. Fluorescence spectra studies revealed structural conformation of acylated soy peptides as compared to native peptides. This study shows that chemical modification with fatty acids can further affect functional properties of soy proteins. PMID:22429318

Matemu, Athanasia Oswald; Katayama, Shigeru; Kayahara, Hisataka; Murasawa, Hisashi; Nakamura, Soichiro

2012-04-01

73

Surface studies of aminoferrocene derivatives on gold: electrochemical sensors for chemical warfare agents.  

PubMed

The cystamine conjugate [(BocNH)Fc(CO)CSA]2 was prepared by coupling cystamine with the N-protected ferrocene amino acid derivative BocHN-Fc-COOH and was fully characterized by spectroscopic methods and by single-crystal X-ray diffraction. The cystamine conjugate forms films on gold substrates, which upon deprotection of the amino group, react with chemical warfare agent (CWA) mimics, upon which the redox properties of the Fc group are affected significantly. Cyclic voltammetry shows 50(5) mV anodic shifts of the Fc redox potentials after exposure to EtSCH2CH2Cl, a simulant for sulfur mustard HD (MA), and (NC)(EtO)2P(O), a simulant for nerve agent Tabun (NA). Exposure to MA and NA causes an increase in 2.3 and 4.5 ng mass, respectively, in QCM which indicates ca. 70% efficiency in Boc-deprotection. Ellipsometry measured a film thickness increase from 6(+/-1) A for the deprotected film to 10(+/-4) A for the film modified with MA and to 7(+/-2) A for the film modified with NA. AFM measurements show changes in the thickness and morphology of the film after reaction with MA and NA. The surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) and clearly show the attachment of the cystamine conjugate on the surface and its reaction with CWA mimics. PMID:17319647

Khan, Mohammad A K; Long, Yi-Tao; Schatte, Gabriele; Kraatz, Heinz-Bernhard

2007-04-01

74

Two-Dimensional Carbon Compounds Derived from Graphyne with Chemical Properties Superior to Those of Graphene  

PubMed Central

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

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

2013-01-01

75

Catalytic conversion of biomass pyrolysis-derived compounds with chemical liquid deposition (CLD) modified ZSM-5.  

PubMed

Chemical liquid deposition (CLD) with KH550, TEOS and methyl silicone oil as the modifiers was used to modify ZSM-5 and deposit its external acid sites. The characteristics of modified catalysts were tested by catalytic conversion of biomass pyrolysis-derived compounds. The effects of different modifying conditions (deposited amount, temperature, and time) on the product yields and selectivities were investigated. The results show KH550 modified ZSM-5 (deposited amount of 4%, temperature of 20°C and time of 6h) produced the maximum yields of aromatics (24.5%) and olefins (16.5%), which are much higher than that obtained with original ZSM-5 catalyst (18.8% aromatics and 9.8% olefins). The coke yield decreased from 44.1% with original ZSM-5 to 26.7% with KH550 modified ZSM-5. The selectivities of low-molecule-weight hydrocarbons (ethylene and benzene) decreased, while that of higher molecule-weight hydrocarbons (propylene, butylene, toluene, and naphthalene) increased comparing with original ZSM-5. PMID:24413482

Zhang, Huiyan; Luo, Mengmeng; Xiao, Rui; Shao, Shanshan; Jin, Baosheng; Xiao, Guomin; Zhao, Ming; Liang, Junyu

2014-03-01

76

Derivatives  

NSDL National Science Digital Library

Murray Bourne developed the Interactive Mathematics site while working as a mathematics lecturer at Ngee Ann Polytechnic in Singapore. The site contains numerous mathematics tutorials and resources for students and teachers alike. This specific page is focused on differentiation, or finding derivatives. Bourne walks users through an introduction to differentiation and limits, and then moves on to more specific applications like rate of change, derivatives of polynomials, and differentiating powers of a function. Each topic includes graphs and interactive materials designed to aid users in understanding the presented concepts. The information here is presented in a clear, straightforward manner that is appropriate for introductory and advanced calculus students alike.

Bourne, Murray

2008-04-22

77

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

Microsoft Academic Search

Toxicological hazard and risk assessments for chemicals presently are mainly based on highly standardised protocols for animal experimentation and exposure assessment. In this paper the possibilities are being discussed of developing systems in which the systemic (acute and chronic) toxicity of chemicals can be quantified, without the heavy reliance on animal experiments. On the basis of a chemical's structure, in

Bas J Blaauboer

2002-01-01

78

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

79

Evaluation of adamantane derivatives for chemically amplified resist: a comparison between ArF, EUV, and EB exposures  

NASA Astrophysics Data System (ADS)

Photoresists containing adamantane derivatives have been widely used with ArF exposure tools. However, the performance characteristics of adamantane derivatives with other optical sources, such as extreme ultraviolet (EUV) and electron beam (EB) sources, have not been well-studied. To clarify such performance characteristics for several exposure sources, we synthesized acrylic terpolymers containing adamantyl methacrylates as model photopolymers and exposed the resist samples based on these polymers to ArF, EUV and EB radiations. On the basis of the lithographic performance characteristics of these resist samples, we evaluated the performance characteristics of adamantane derivatives upon exposure to different radiations. We discuss the relationship between the chemical structures of adamantane derivatives and lithographic performance characteristics.

Furukawa, Kikuo; Seki, Shu; Kozawa, Takahiro; Tagawa, Seiichi

2008-04-01

80

Primary cilia: the chemical antenna regulating human adipose-derived stem cell osteogenesis.  

PubMed

Adipose-derived stem cells (ASC) are multipotent stem cells that show great potential as a cell source for osteogenic tissue replacements and it is critical to understand the underlying mechanisms of lineage specification. Here we explore the role of primary cilia in human ASC (hASC) differentiation. This study focuses on the chemosensitivity of the primary cilium and the action of its associated proteins: polycystin-1 (PC1), polycystin-2 (PC2) and intraflagellar transport protein-88 (IFT88), in hASC osteogenesis. To elucidate cilia-mediated mechanisms of hASC differentiation, siRNA knockdown of PC1, PC2 and IFT88 was performed to disrupt cilia-associated protein function. Immunostaining of the primary cilium structure indicated phenotypic-dependent changes in cilia morphology. hASC cultured in osteogenic differentiation media yielded cilia of a more elongated conformation than those cultured in expansion media, indicating cilia-sensitivity to the chemical environment and a relationship between the cilium structure and phenotypic determination. Abrogation of PC1, PC2 and IFT88 effected changes in both hASC proliferation and differentiation activity, as measured through proliferative activity, expression of osteogenic gene markers, calcium accretion and endogenous alkaline phosphatase activity. Results indicated that IFT88 may be an early mediator of the hASC differentiation process with its knockdown increasing hASC proliferation and decreasing Runx2, alkaline phosphatase and BMP-2 mRNA expression. PC1 and PC2 knockdown affected later osteogenic gene and end-product expression. PC1 knockdown resulted in downregulation of alkaline phosphatase and osteocalcin gene expression, diminished calcium accretion and reduced alkaline phosphatase enzymatic activity. Taken together our results indicate that the structure of the primary cilium is intimately associated with the process of hASC osteogenic differentiation and that its associated proteins are critical players in this process. Elucidating the dynamic role of the primary cilium and its associated proteins will help advance the application of hASC in generating autologous tissue engineered therapies in critical defect bone injuries. PMID:23690943

Bodle, Josephine C; Rubenstein, Candace D; Phillips, Michelle E; Bernacki, Susan H; Qi, Jie; Banes, Albert J; Loboa, Elizabeth G

2013-01-01

81

A physico-chemical and biological study of novel chitosan-chloroquinoline derivative for biomedical applications.  

PubMed

This paper describes an elegant cross-linking technique for the preparation of chitosan-chloroquinoline derivative by using a greener technique. Chitosan solution in aqueous acetic acid was treated with 2-chloroquinoline-3-carbaldehyde solution to form hydrogel; the resulting hydrogel was subjected to solvent exchange. Combining the results of FTIR and XRD confirmed that 2-chloroquinoline-3-carbaldehyde have been reacted to chitosan. The morphology of the derivative was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability of the derivative was examined by thermogravimetric analysis (TGA). The photoluminescence (PL) spectra of chitosan-chloroquinoline derivative show red-shifted emission maximum. The microbiological screening has demonstrated the antimicrobial activity of the derivative against bacteria viz. Staphylococcus aureus, Escherichia coli and Candida albicans. The obtained results showed that the chitosan-chloroquinoline derivative might be a promising candidate for novel antimicrobial agents for biomedical applications. PMID:21640132

Kumar, Santosh; Dutta, P K; Koh, Joonseok

2011-10-01

82

Paper derived biomorphic porous titanium carbide and titanium oxide ceramics produced by chemical vapor infiltration and reaction (CVI-R)  

Microsoft Academic Search

Chemical vapor infiltration (CVI) is used for producing biomorphic porous TiC ceramics derived from paper. The paper samples are first carbonized in inert atmosphere to yield biocarbon template structures (Cb-template). Subsequently, three routes for converting the Cb-templates into TiC ceramics are studied. The first route includes CVI with TiCl4-H2. The effect of methane as additional carbon source is investigated on

Nadja Popovska; Daniela Almeida Streitwieser; Chen Xu; Helmut Gerhard

2005-01-01

83

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

2014-07-01

84

Chemical ozone loss in Arctic and Antarctic polar vortices derived from SCIAMACHY limb-scattered solar radiation  

NASA Astrophysics Data System (ADS)

Stratospheric ozone profiles are retrieved for the period 2002 -2009 from SCIAMACHY mea-surements of limb-scattered solar radiation in the Hartley and Chappuis absorption bands of ozone. This data set is used to determine the chemical ozone loss in both placeArctic and Antarctic polar vortices using the vortex average method. The chemical ozone loss at the 450 -600 K isentropic levels is derived from the difference between observed ozone abundances and the ozone modeled considering diabatic cooling, but no chemical ozone loss. At the 475 K isentropic level, the results show accumulated chemical ozone losses of up to 20 -40% be-tween the beginning of January and the end of March inside the Arctic polar vortex. Strong inter-annual variability of the Arctic ozone loss is observed, with the cold winters 2004/2005 and 2006/2007 showing the largest chemical ozone losses. The Antarctic vortex averaged ozone loss does not vary much from year to year. The ozone losses of 70 -80% between mid-August and mid-November are observed every year inside the vortex, also in the anomalous year 2002. However, because the variations in the size of the polar vortex lead to inter-annual changes in total ozone mass loss, the polar vortex size is determined and the total mass of ozone chemically lost inside the polar vortex is estimated. Comparisons of the vertical variation of ozone loss derived from SCIAMACHY observations with several independent techniques for the northern hemisphere winter 2004/2005 show very good agreement.

Sonkaew, Thiranan; von Savigny, Christian; Eichmann, Kai-Uwe; Weber, Mark; Rozanov, Alexei; Bovensmann, Heinrich; Burrows, John P.

85

Chemical solution deposition derived buffer layers for MOCVD-grown GaN films  

Microsoft Academic Search

A polymeric Ga-containing liquid precursor was used for the first time to prepare a buffer layer for the growth of GaN by metalorganic chemical vapor deposition. The buffer layer was prepared by chemical solution deposition (CSD), i.e. spincoating the precursor on a sapphire substrate followed by pyrolysis in ammonia. The GaN films were characterized by optical and electron microscopy, XRD

Manfred Puchinger; Thomas Wagner; Paul Fini; David Kisailus; Ulrich Beck; Joachim Bill; Fritz Aldinger; Eduard Arzt; Frederick F Lange

2001-01-01

86

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

87

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.

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

2013-01-01

88

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

Microsoft Academic Search

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 1 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

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

2000-01-01

89

HEMP-derived activated carbon fibers by chemical activation with phosphoric acid  

Microsoft Academic Search

Activated carbon fibers were prepared by chemical activation of hemp fibers with phosphoric acid at different carbonization temperatures and impregnation ratios. Surface properties of the activated carbons fibers were significantly influenced by the activation temperature and the impregnation ratio. An increase of either of these parameters produced a high development of the porous structure of the fibers. Activated carbon fibers

J. M. Rosas; J. Bedia; J. Rodríguez-Mirasol; T. Cordero

2009-01-01

90

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

Microsoft Academic Search

Limonoids are heavily oxygenated, modified triterpenes dominant in Meliaceae and Rutaceae plant families. The term limonoid derived from limonin, that 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

Rosa Tundis; Monica Rosa Loizzo; Francesco Menichini

2012-01-01

91

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

PubMed

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

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

2013-12-01

92

Chemical nature of implant-derived titanium(IV) ions in synovial fluid  

Microsoft Academic Search

Previous investigations have indicated a deleterious leakage of Ti(III) and\\/or Ti(IV) species from Ti–Al–V alloy joint prostheses into adjacent tissue, synovium or synovial fluid (SF) in vivo. In view of the importance of the particular chemical nature of such complexes in determining their biological activity, we have employed high field proton (1H) NMR spectroscopy to “speciate” Ti(IV) in inflammatory SF.

Christopher J. L. Silwood; Martin. Grootveld

2005-01-01

93

Chemical reactivities of hafnium and its derived boride, carbide and nitride compounds at relatively mild temperature  

Microsoft Academic Search

MB2\\/SiC composites are materials of choice for ultra-high-temperature structural applications, primarily in the aerospace arena. These composites are processed in a hot-press operation at a temperature range of 1900 to 2200°C. This article assesses potential “mild-temperature” (below 1500°C) chemical reactions that may lead to structures and coatings made of HfB2\\/SiC under pressureless or mild-pressure conditions. The reactions are anticipated to

Y. D. Blum; H.-J. Kleebe

2004-01-01

94

Sono-chemical preparation of cellulose nanocrystals from lignocellulose derived materials  

Microsoft Academic Search

This study examined the production of cellulose nanocrystals from microcrystalline wood cellulose, Avicel and recycled pulp of wood pulp using sono-chemical-assisted hydrolysis. Two hydrolysis systems: deionized water and maleic acid were evaluated. In deionized water, Avicel produced cellulose nanocrystals with average diameter of 21±5nm (minimum 15nm and maximum 32nm). Cellulose nanocrystals from recycled pulp were not distinctively spherical and had

Paul B. Filson; Benjamin E. Dawson-Andoh

2009-01-01

95

Expanding the scope of biomass-derived chemicals through tandem reactions based on oxorhenium-catalyzed deoxydehydration.  

PubMed

New modes of DODH: Oxorhenium compounds act as deoxydehydration(DODH)/acid dual-purpose catalysts to transform biomass-derived diol substrates into a variety of commodity chemical precursors. The power of this approach is highlighted by a tandem [1,3]-OH shift/DODH of 2-ene-1,4-diols and 2,4-diene-1,6-diols, and by a DODH/esterification sequence of sugar acids to unsaturated esters for the production of polymers and plasticizers. PMID:24222362

Shiramizu, Mika; Toste, F Dean

2013-12-01

96

Stability studies on the chemical and biological activity of coal-derived liquids  

SciTech Connect

After four years of storage, no chemical composition or mutagenicity changes occurred in the 17 SRC materials stored in the repository under controlled conditions. The integrity of the samples has been maintained at 4/sup 0/C, in inert containers, in the dark, under a nitrogen atmosphere. After one year of storage of SRC II fuel oil blend (FOB) samples at room temperatures under various parameters of ambient light, cover atmosphere, and dilution, no gross chemical composition changes occurred except when diluted in methylene chloride, in the light, under an air atmosphere. Under these conditions, hydroxylated PAH such as the cresols and indanol decomposed. Also, hydrogenated PAH such as unsubstituted and alkylated indans and tetralins decomposed. Mutagenicity of the FOB was significantly decreased or eliminated when stored both diluted and undiluted at room temperature for one year under an air atmosphere in ambient light. Mutagenicity decreased when no gross chemical compositional changes were noted due to trace component degradation, probably primary aromatic amines. After 32 weeks of storage at 60/sup 0/C, hydroxylated PAH such as o-cresol and indanol degraded in the FOB. Hydrogenated PAH such as alkylated indans also showed a significant decrease. Mutagenicity was completed eliminated under these harsh storage conditions. A more complete discussion of effects of storage under increased temperature on the nitrogen-containing polycyclic aromatic compounds present in the FOB is forthcoming. 13 references, 5 tables.

Wright, C.W.; Daly, C.S.; Weimer, W.C.

1983-10-01

97

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

PubMed

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

Kaewbumrung, Sermwut; Panichayupakaranant, Pharkphoom

2014-01-01

98

Synthesis and optical\\/chemical properties of triphenylamine derivatives based mono-, di-, and tri-indanedione  

Microsoft Academic Search

In this contribution, three triphenylamine derivatives were synthesized and their spectral properties were investigated. Knoevenagel\\u000a condensation of mono-, di-, and tri-aldehydes of triphenylamine with 1,3-indanedione yields D-?-A type dyes with push-pull\\u000a chromophores. The absorption and luminescence properties of the dyes were discussed in terms of their electronic structures.\\u000a The results of molecular orbital computer simulations, based on Material Studio, were

Xiaochuan Li; Young-Sung Kim; Sung-Hoon Kim; Kun Jun; Young-A Son

2009-01-01

99

[Synthesis and physico-chemical characterisation of some new derivatives of rutoside and clofibric acid].  

PubMed

Fibrates are drugs with efficacy in reducing blood cholesterol levels and especially, triglyceride plasma levels. Unfortunately, fibrates have a poor water-solubility and showed some adverse reactions at long treatment. The objective of this study was to obtain some new clofibric acid derivatives with rutin; some of these compounds contain a guanidine moiety, known as effective at cardiovascular level. All the compounds are soluble in water. PMID:19292111

Lupa?cu, D; Profire, Lenu?a; D?nil?, Gh

2006-01-01

100

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

Microsoft Academic Search

Executive Summary;\\u000aThe growing gap between petroleum production and demand, mounting environmental concerns,;\\u000aand increasing fuel prices have stimulated intense interest in research and development (R&D) of;\\u000aalternative fuels, both synthetic and bio-derived. Currently, the most technically defined;\\u000athermochemical route for producing alternative fuels from lignocellulosic biomass involves;\\u000agasification\\/reforming of biomass to produce syngas (carbon monoxide [CO] + hydrogen [H2]),;

David C. Dayton

2010-01-01

101

13C and 1H MAS NMR studies of graphite oxide and its chemically modified derivatives  

Microsoft Academic Search

Graphite oxide (GO) and several of its derivatives have been studied using 13C and 1H NMR. The 13C NMR lines at 60, 70 and 130 ppm have been re-assigned. The > C?C < double bonds are relatively stable in comparison with the C?O?C and C?O?H groups. There are at least two magnetically inequivalent C?O?H sites, and the structure does not

Anton Lerf; Heyong He; Thomas Riedl; Michael Forster; Jacek Klinowski

1997-01-01

102

Correlation between chemical structure and biological activities of Porphyromonas gingivalis synthetic lipopeptide derivatives  

PubMed Central

We recently separated a PG1828-encoded triacylated lipoprotein (Pg-LP), composed of two palmitoyl and one pentadecanoyl groups at the N-terminal of glycerocysteine from Porphyromonas gingivalis, a periodontopathic bacteria, and found that Pg-LP exhibited definite biological activities through Toll-like receptor (TLR) 2. In the present study, we synthesized 12 different Pg-LP N-terminal peptide moieties (PGTP) using four combinations of glyceryl (R and S) and cysteinyl (l and d) stereoisomers, and three different acyl group regioisomers, N-pentadecanoyl derivative (PGTP1), S-glycero 2-pentadecanoyl derivative (PGTP2) and S-glycero 3-pentadecanoyl derivative (PGTP3). All the PGTP compounds (RL, SL, SD, RD) tested showed TLR2-dependent cell activation. The activating capacities of the PGTP-R compounds were more potent than those of the PGTP-S compounds, whereas there were no differences between the PGTP-L and -D compounds. Furthermore, the production of interleukin (IL)-6 following stimulation with the PGTP1-RL, PGTP2-RL and PGTP3-RL compounds was impaired in peritoneal macrophages from TLR2 knock-out (KO), but not those from TLR1 KO or TLR6 KO mice. These results suggest that P. gingivalis triacylated lipopeptides are capable of activating host cells in a TLR2-dependent and TLR1-/TLR6-independent manner, and the fatty acid residue at the glycerol position in the PGTP molecule plays an important role in recognition by TLR2.

Makimura, Y; Asai, Y; Taiji, Y; Sugiyama, A; Tamai, R; Ogawa, T

2006-01-01

103

Quantum Chemical Study of Raman Spectroscopy of Substituted Benzene Derivatives Adsorbed on Metal Surfaces  

NASA Astrophysics Data System (ADS)

Surface-enhanced Raman spectroscopy (SERS) can be applied to obtain the information of molecules at the noble metal surfaces. But there are a number of difficulties to clearly correlate Raman spectra with microscopic molecular structures on metal surfaces. The main reason is that it is difficult to characterize unambiguously the metal surface structures and the influence of the binding interaction on SERS signals of the probe molecules. According to the surface selection rule of SERS, the electromagnetic enhancement will not change relative Raman intensities of vibrational modes with the same irreducible representation. Therefore, the change of the relative Raman intensities of the total symmetric modes may only originate from the chemical enhancement. In order to understand how the chemical interaction modulates the Raman intensity of individual modes, it is necessary to systematically investigate the Raman spectra of probe molecules themselves and the dependence of SERS signals on the binding interaction, adsorption sites, excitation wavelengths and metal property. Some probe molecules, including aniline, 1,4-benzenediamine, p-aminothiophenol, benzyl chlorine, and 4,4^'-bipyridine are investigated based on quantum chemical calculations. Raman spectra of these molecules and their adsorbed species were predicted and compared with experimentally measured spectra. The metal surfaces were mimicked using the metallic cluster model, where the silver or gold surfaces were replaced by silver or gold clusters, respectively. The density functional theory approach was employed to obtain the optimized structures and vibrational spectra by combining all-electron basis sets of 6-311+G** for atoms in the molecules and the poseudopotential basis set of LANL2DZ for metal atoms. The vibrational frequency shift and the relative Raman intensity are related to the adsorption configuration of the probe molecules. For all these molecules, the ring breathing mode and the C-C stretching mode show the strongest SERS signals and are sensitive to the binding interaction. They play an important role in obtaining the adsorption structure of molecules on metal surfaces.

Wu, De-Yin; Tian, Zhong-Qun

2011-06-01

104

Deriving model-based Te-consistent chemical abundances in ionized gaseous nebulae  

NASA Astrophysics Data System (ADS)

The derivation of abundances in gaseous nebulae ionized by massive stars using optical collisionally excited emission lines is studied in this work, comparing the direct or Te method with updated grids of photoionization models covering a wide range of input conditions of O/H and N/O abundances and ionization parameter. The abundances in a large sample of compiled objects with at least one auroral line are re-derived and later compared with the ?2-weighted-mean abundances from the models. The agreement between the abundances using the two methods both for O/H and N/O is excellent with no additional assumptions about the geometry or physics governing the H II regions. Although very inaccurate model-based O/H are obtained when no auroral lines are considered, this can be overcome assuming empirical laws between O/H, log U, and N/O to constrain the considered models. In this way, for 12+log(O/H) > 8.0, a precision better than 0.1 dex consistent with the direct method is attained. For very low Z, models give higher O/H values and a high dispersion, possibly owing to the contamination of the low-excitation emission lines. However, in this regime, the auroral lines are usually well detected. The use of this procedure, in a publicly available script, HII-CHI-MISTRY, leads to the derivation of abundances in faint-/high-redshift objects consistent with the direct method based on collisionally excited lines.

Pérez-Montero, E.

2014-07-01

105

Chemical Derivatives of a Small Molecule Deubiquitinase Inhibitor Have Antiviral Activity against Several RNA Viruses  

PubMed Central

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

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

2014-01-01

106

Chemical Derivatives of a Small Molecule Deubiquitinase Inhibitor Have Antiviral Activity against Several RNA Viruses.  

PubMed

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

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

2014-01-01

107

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.

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

2014-01-01

108

Extreme chemical heterogeneity of granite-derived hydrothermal fluids: An example from inclusions in a single crystal of miarolitic quartz  

NASA Astrophysics Data System (ADS)

Magma-derived fluids are important in geologic processes (e.g., metal sequestration and ore deposition) but are intrinsically transient. Samples of magmatic fluids represented by fluid inclusions in a single zoned quartz crystal from a miarolitic cavity within a porphyritic leucogranite hosting the Industrialnoe tin deposit, northeastern Russia, were studied by using modern in situ analytical methods (laser Raman spectroscopy, proton-induced X-ray emission). The fluid inclusions are either dominated by vapor or by complex multiphase brines. The inclusions within a given trapping plane have similar phase relationships; however, there are significant variations between inclusions in different healed fractures. Phase and chemical compositions of individual brine inclusions demonstrate significant compositional heterogeneity (in terms of absolute element concentrations and ratios) of high-temperature magmatic fluids accumulated in the miarolitic cavity. This finding suggests that fluids leaving a crystallizing magma may have variable initial compositions that are subsequently modified by reactions with the rocks while the fluid is in transit to a miarolitic cavity, as well as by processes in the cavity, such as mixing, crystallization, and boiling. The inferred chemical diversity and fractionation of granite-derived fluids at near-magmatic conditions imply that fluids entering a cooler hydrothermal system are extremely complex and their metallogenic signature may differ from that of related ore deposits.

Kamenetsky, Vadim S.; van Achterbergh, Esme; Ryan, Chris G.; Naumov, Vladimir B.; Mernagh, Terrence P.; Davidson, Paul

2002-05-01

109

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

110

Atmospheric pressure chemical ionisation liquid chromatography/multistage mass spectrometry for assignment of sedimentary bacteriochlorophyll derivatives.  

PubMed

Atmospheric pressure chemical ionisation liquid chromatography/multistage mass spectrometry (APCI-LC/MSn) provides a rapid, on-line method for the assignment of individual bacteriophaeophorbide c and d methyl esters (BPMEs) in complex mixtures. The MS2 spectrum for each component is diagnostic of the type of BPME (c or d), and characteristic losses in MS5 and MS6 permit assignment of the alkyl substituents at positions C-8 and C-12 of the macrocycle. MS5 mass chromatograms permit the deconvolution of coeluting isobaric BPMEs, revealing the true profiles of the individual components. The distributions are different in lake sediments from la Salada de Chiprana (Spain) and Kirisjes Pond (Antarctica), and a novel BPME c with a neo-pentyl substituent has been observed in the Kirisjes Pond sediment. PMID:15570571

Wilson, Michael A; Hodgson, Dominic A; Keely, Brendan J

2005-01-01

111

Two-photon absorption in oxazole derivatives: An experimental and quantum chemical study  

NASA Astrophysics Data System (ADS)

Experimental and theoretical studies on the two-photon absorption properties of two oxazole derivatives: 2,5-diphenyloxazole (PPO) and 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) are presented. The two-photon absorption cross-section spectra were determined by means of the Z-scan technique, from 460 up to 650 nm, and reached peak values of 84 GM for PBD and 27 GM for PPO. Density Functional Theory and response function formalism are used to determine the molecular structures and the one- and two-photon absorption properties and to assist in the interpretation of the experimental results. The Polarizable Continuum Model in one-photon absorption calculations is used to estimate solvent effects.

Silva, D. L.; De Boni, L.; Correa, D. S.; Costa, S. C. S.; Hidalgo, A. A.; Zilio, S. C.; Canuto, S.; Mendonca, C. R.

2012-05-01

112

Chemical profiling of seized methamphetamine putatively synthesized from phenylacetic acid derivatives.  

PubMed

We report a case of seized crystalline methamphetamine (MA) samples showing unique drug profiles. The samples were mainly composed of (S)-(+)-MA, with each containing a slight amount of (R)-(-)-MA (enantiomeric excess: 99.2-99.4%). 1-Phenyl-2-propanol and N-methyl-2-phenylacetamide were detected as characteristic impurities. These analytical results suggested that the samples were synthesized as racemic MA by reductive amination of 1-phenyl-2-propanone, which was synthesized from phenylacetic acid, putatively prepared from phenylacetic acid ester, and then the racemic MA was optically resolved to the (+)-form-rich product. This proposed preparation route was in accordance with recent reports of seizures worldwide of the raw materials of MA such as phenylacetic acid derivatives, methylamine, and tartaric acid (optical resolving reagent). PMID:22989601

Tsujikawa, Kenji; Kuwayama, Kenji; Miyaguchi, Hajime; Kanamori, Tatsuyuki; Iwata, Yuko T; Inoue, Hiroyuki

2013-04-10

113

Chemical inducers of heat shock proteins derived from medicinal plants and cytoprotective genes response.  

PubMed

Environmental stress induces damage that activates an adaptive response in any organism. The cellular stress response is based on the induction of cytoprotective proteins, the so-called stress or heat shock proteins (HSPs). HSPs are known to function as molecular chaperones which are involved in the therapeutic approach of many diseases. Therefore in the current study we searched nontoxic chaperone inducers in chemical compounds isolated from medicinal plants. Screening of 80 compounds for their Hsp70-inducing activity in human lymphoma U937 cells was performed by western blotting. Five compounds showed significant Hsp70 up-regulation among them shikonin was most potent. Shikonin was able to induce Hsp70 at 0.1?µM after 3?h without activation of heat shock transcription factor 1 (HSF-1). It also induces significant reactive oxygen species generation. The expression level of genes responsive to shikonin was studied using global-scale microarrays and computational gene expression analysis tools. Significant increase in the nuclear factor erythroid 2-related factor 2 (Nrf2, NFEL2L2) -mediated oxidative stress response was observed that leads to the activation of HSP. The results of gene chip analysis were further confirmed by real-time qPCR assay. In short, the detailed mechanisms of Hsp70 induction by shikonin is not fully understood, Nrf2 and its target genes might be involved in the Hsp70 up-regulation in U937 cells. PMID:22235779

Ahmed, Kanwal; Furusawa, Yukihiro; Tabuchi, Yoshiaki; Emam, Heba F; Piao, Jin-Lan; Hassan, Mariame Ali; Yamamoto, Takeshi; Kondo, Takashi; Kadowaki, Makoto

2012-01-01

114

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

115

Biomass-derived chemicals: synthesis of biodegradable surfactant ether molecules from hydroxymethylfurfural.  

PubMed

A new class of biodegradable anionic surfactants with structures based on 5-alkoxymethylfuroate was prepared starting from 5-hydroxymethylfurfural (HMF), through a one-pot-two-steps process which involves the selective etherification of HMF with fatty alcohols using heterogeneous solid acid, followed by a highly selective oxidation of the formyl group with a gold catalyst. The etherification step was optimized using aluminosilicates as acid catalysts with different pore topologies (H-Beta, HY, Mordenite, ZSM-5, ITQ-2, and MCM-41), different active sites (Bronsted or Lewis) and different adsorption properties. It was shown that highly hydrophobic defect-free H-Beta zeolites with Si/Al ratios higher than 25 are excellent acid catalysts to perform the selective etherification of HMF with fatty alcohols, avoiding the competitive self-etherification of HMF. Moreover, the 5-alkoxymethylfurfural derivatives obtained can be selectively oxidized to the corresponding furoic salts in excellent yield using Au/CeO2 as catalyst and air as oxidant, at moderated temperatures. Both H-Beta zeolite and Au/CeO2 could be reused several times without loss of activity. PMID:24106062

Arias, Karen S; Climent, Maria J; Corma, Avelino; Iborra, Sara

2014-01-01

116

Chemical Evolution of Amphiphiles: Glycerol Monoacyl Derivatives Stabilize Plausible Prebiotic Membranes  

NASA Astrophysics Data System (ADS)

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°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.

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

2009-12-01

117

Theoretical predictions of chemical degradation reaction mechanisms of RDX and other cyclic nitramines derived from their molecular structures.  

PubMed

Analysis of environmental degradation pathways of contaminants is aided by predictions of likely reaction mechanisms and intermediate products derived from computational models of molecular structure. Quantum mechanical methods and force-field molecular mechanics were used to characterize cyclic nitramines. Likely degradation mechanisms for hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) include hydroxylation utilizing addition of hydroxide ions to initiate proton abstraction via 2nd order rate elimination (E2) or via nucleophilic substitution of nitro groups, reductive chemical and biochemical degradation, and free radical oxidation. Due to structural similarities, it is predicted that, under homologous circumstances, certain RDX environmental degradation pathways should also be effective for octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and similar cyclic nitramines. Computational models provided a theoretical framework whereby likely transformation mechanisms and transformation products of cyclic nitramines were predicted and used to elucidate in situ degradation pathways. PMID:15804809

Qasim, M; Fredrickson, H; McGrath, C; Furey, J; Bajpai, R

2005-06-01

118

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

USGS Publications Warehouse

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

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

2001-01-01

119

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

120

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

121

Local Electronic and Chemical Structure of Oligo-acetylene Derivatives Formed Through Radical Cyclizations at a Surface  

PubMed Central

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.

2014-01-01

122

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

PubMed

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

Jang, Goo; Hong, So Gun; Lee, Byeong Chun

2011-03-01

123

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

PubMed

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

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

2014-05-01

124

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

PubMed Central

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

Hong, So Gun

2011-01-01

125

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

PubMed Central

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

2014-01-01

126

The 2D Rancieite-type manganic acid and its alkali-exchanged derivatives: Part I — Chemical characterization and thermal behavior  

Microsoft Academic Search

The 2D Rancieite type manganic acid was prepared by reduction of KMnO4 in acidic medium. Its ion exchange behavior allows to prepare alkali derivatives. All compounds were characterized with use of a combination of X-ray diffraction, chemical analyses, TGA, magnetic measurements and spectroscopic techniques. The evolution of their chemical composition versus temperature was studied between 180 and 400 °C. It

F. Leroux; D. Guyomard; Y. Piffard

1995-01-01

127

Differentiation between isomeric 1-aminocyclo-propane- 1 - carboxylic acid derivatives by means of chemical ionisation and mass selected collision induced dissociation  

NASA Astrophysics Data System (ADS)

Chemical ionisation in ammonia and in methane, electron impact ionisation and mass selected collision induced dissociation involving 10 1-aminocyclopropane- 1 -carboxylic acid derivatives are reported. The data presented, exhibit a number of qualitative differences which are attributed to the different isomeric structures of the investigated precursors. Competition between protonation and addition reaction channels which yield MH+ and [M + NH4]+ in ammonia, chemical ionisation and the different internal excitation experienced by ions formed in chemical ionisation, and by electron impact, are two experimental observations which the present work seeks to underline.

Hamdan, M.; Curcuruto, O.; Tarzia, G.; Balsamini, C.; Bedini, A.; Spadoni, G.

1993-04-01

128

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

129

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

130

Aerosol hygroscopicity derived from size-segregated chemical composition and its parameterization in the North China Plain  

NASA Astrophysics Data System (ADS)

Hygroscopic growth of aerosol particles is of significant importance in quantifying the aerosol radiative effect in the atmosphere. In this study, hygroscopic properties of ambient particles are investigated based on particle chemical composition at a suburban site in the North China Plain during the HaChi campaign (Haze in China) in summer 2009. The size-segregated aerosol particulate mass concentration as well as the particle components such as inorganic ions, organic carbon and water-soluble organic carbon (WSOC) is identified from aerosol particle samples collected with a 10-stage impactor. An iterative algorithm is developed to evaluate the hygroscopicity parameter ? from the measured particle chemical compositions. During the HaChi summer campaign, almost half of the mass concentration of particles between 150 nm and 1 ?m is contributed by inorganic species. Organic matter (OM) is abundant in ultrafine particles, and 77% of the particulate mass with diameter (Dp) around 30 nm is composed of OM. A large fraction of coarse particle mass is undetermined and is assumed to be insoluble mineral dust and liquid water. The campaign average size distribution of ? values shows three distinct modes: the less hygroscopic mode (Dp < 150 nm) with ? slightly above 0.2, the highly hygroscopic mode (150 nm 1 ?m) with ? about 0.1. The peak of the ? curve appears around 450 nm with a maximum value of 0.35. The derived ? values are consistent with results measured with a High Humidity Tandem Differential Mobility Analyzer within the size range of 50 nm to 250 nm. Inorganics are the predominant species contributing to particle hygroscopicity, especially for particles between 150 nm and 1 ?m. For example, NH4NO3, H2SO4, NH4HSO4 and (NH4)2SO4 account for nearly 90% of ? for particles around 900 nm. For ultrafine particles, WSOC plays a critical role in particle hygroscopicity due to the predominant mass fraction of OM in ultrafine particles. 52% of ? is contributed by WSOC for particles around 30 nm. Aerosol particles are more hygroscopic during daytime, which can result from the diurnal evolution of planetary boundary layer, photochemical aging process during daytime and enhanced elemental carbon emission at night. ? is highly correlated with mass fractions of SO42-, NO3- and NH4+ for all sampled particles as well as with the mass fraction of WSOC for particles less than 100 nm. A parameterization scheme of ? is developed using mass fractions of SO42-, NO3-, NH4+ and WSOC due to their high correlations with ?, and ? calculated from parameterization agrees well with ? derived from the particle chemical composition. Further analysis shows that the parameterization scheme is applicable to other aerosol studies in China.

Liu, H. J.; Zhao, C. S.; Nekat, B.; Ma, N.; Wiedensohler, A.; van Pinxteren, D.; Spindler, G.; Müller, K.; Herrmann, H.

2013-08-01

131

Aerosol hygroscopicity derived from size-segregated chemical composition and its parameterization in the North China Plain  

NASA Astrophysics Data System (ADS)

Hygroscopic growth of aerosol particles is of significant importance in quantifying the aerosol radiative effect in the atmosphere. In this study, hygroscopic properties of ambient particles are investigated based on particle chemical composition at a suburban site in the North China Plain during the HaChi campaign (Haze in China) in summer 2009. The size-segregated aerosol particle mass concentration as well as the particle components such as inorganic ions, organic carbon and water-soluble organic carbon (WSOC) is identified from aerosol particle samples collected with a 10-stage Berner Low Pressure Impactor. An iterative algorithm is developed to evaluate the hygroscopicity parameter ? from the measured particle chemical compositions. During the HaChi summer campaign, almost half the mass concentration of particles between 150nm and 1?m is contributed by inorganic species. Organic matter (OM) is abundant in ultrafine particles, and 77% of the particle mass of particles in impactor stage 2 (diameter (Dp) around 30nm) is composed of OM. A large fraction of coarse particles is undetermined, which is suggested to be constituted of insoluble mineral dust and liquid water. The campaign average size distribution of ? values shows three distinct modes: the less hygroscopic mode (Dp<150nm) with ? slightly above 0.2, the highly hygroscopic mode (150nm1?m) with ? around 0.1. The peak of the ? curve appears around 450nm with a maximum value of 0.35. The derived ? values are consistent with results measured with a High Humidity Tandem Differential Mobility Analyzer within the size range of 50 to 250nm. Inorganics are the predominant species contributing to particle hygroscopicity, especially for particles between 150nm and 1?m. For example, NH4NO3, H2SO4, NH4HSO4 and (NH4)2SO4 account for nearly 90% of ? for particles in impactor stage 7 (Dp~900nm). For ultrafine particles, WSOC plays a critical role in particle hygroscopicity due to the predominant mass fraction of OM in ultrafine particles. 52% of ? is contributed by WSOC for particles in impactor stage 2 (Dp~30nm). Aerosol particles are more hygroscopic during daytime, which can result from the diurnal evolution of planetary boundary layer, photochemical aging process during daytime and enhanced elemental carbon emission at night. ? is highly correlated with mass fractions of SO42-, NO3- and NH4+ for all sampled particles as well as with the mass fraction of WSOC for particles in impactor stage 2 and 3 (Dp<100nm). A parameterization scheme of ? is developed using mass fractions of SO42-, NO3-, NH4+ and WSOC due to their high correlations with ?, and ?reg calculated from parameterization agrees well with ? derived from the particle chemical composition. Further analysis shows that the parameterization scheme is applicable to other aerosol studies in China.

LIU, H.; Zhao, C.

2013-12-01

132

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

PubMed

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

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

2005-12-15

133

Optimisation of chemical purification conditions for direct application of solid metal salt coagulants: treatment of peatland-derived diffuse runoff.  

PubMed

The drainage of peatland areas for peat extraction, agriculture or bioenergy requires affordable, simple and reliable treatment methods that can purify waters rich in particulates and dissolved organic carbon. This work focused on the optimisation of chemical purification process for the direct dosage of solid metal salt coagulants. It investigated process requirements of solid coagulants and the influence of water quality, temperature and process parameters on their performance. This is the first attempt to provide information on specific process requirements of solid coagulants. Three solid inorganic coagulants were evaluated: aluminium sulphate, ferric sulphate and ferric aluminium sulphate. Pre-dissolved aluminium and ferric sulphate were also tested with the objective of identifying the effects of in-line coagulant dissolution on purification performance. It was determined that the pre-dissolution of the coagulants had a significant effect on coagulant performance and process requirements. Highest purification levels achieved by solid coagulants, even at 30% higher dosages, were generally lower (5%-30%) than those achieved by pre-dissolved coagulants. Furthermore, the mixing requirements of coagulants pre-dissolved prior to addition differed substantially from those of solid coagulants. The pH of the water samples being purified had a major influence on coagulant dosage and purification efficiency. Ferric sulphate (70 mg/L) was found to be the best performing solid coagulant achieving the following load removals: suspended solids (59%-88%), total organic carbon (56%-62%), total phosphorus (87%-90%), phosphate phosphorus (85%-92%) and total nitrogen (33%-44%). The results show that the use of solid coagulants is a viable option for the treatment of peatland-derived runoff water if solid coagulant-specific process requirements, such as mixing and settling time, are considered. PMID:23923774

Heiderscheidt, Elisangela; Saukkoriipi, Jaakko; Ronkanen, Anna-Kaisa; Kløve, Bjørn

2013-04-01

134

Calculation of the 13C NMR chemical shift of ether linkages in lignin derived geopolymers: . Constraints on the preservation of lignin primary structure with diagenesis  

NASA Astrophysics Data System (ADS)

Methodology for the calculation of 13C NMR shieldings on molecular organic fragments, representative of monomers in a type III kerogen, is presented. Geometry optimization of each molecular fragment was carried out using Density Functional Theory employing the generalized gradient approximation. NMR shieldings were calculated using the Individual Gauge for Localized Orbital Method. Convincing agreement was obtained between calculated and experimentally derived isotropic chemical shielding values over a broad frequency range. Shielding calculations employing the localized orbitals/local origin method resulted in nearly identical results. NMR chemical shift static powder patterns also exhibit excellent agreement with experimental values. These quantum mechanical calculations were applied to determine the extent of lignin primary structure preservation with diagenesis. Specifically, the calculations were used to assess whether inhomogeneous spectral broadening due to both functional group variation and local configurational variability may inhibit the detection of otherwise significant quantities of alkyl-aryl ethers in lignin derived geopolymers. Determination of the chemical-shielding tensor principle axis values reveals a strong correlation between anisotropy and asymmetry with local configuration effects such as dihedral rotation, phenyl group rotation, and bond angle variation. These results indicate that a range of 9 ppm in the isotropic chemical shift can be ascribed to local configuration. Consequently, an upper limit of 5% alkyl-aryl-linkages may go undetected using NMR spectroscopy on lignin-derived geopolymers at the liginite-sub-bituminous transition. It is concluded that the primary structure of lignin does not persist in kerogens even at relatively low thermal maturities.

Cody, G. D.; Sághi-Szabó, G.

1999-01-01

135

Calculation of the {sup 13}C NMR chemical shift of ether linkages in lignin derived geopolymers: Constraints on the preservation of lignin primary structure with diagenesis  

SciTech Connect

Methodology for the calculation of {sup 13}C NMR shielding on molecular organic fragments, representative of monomers in a type 3 kerogen, is presented. Geometry optimization of each molecular fragment was carried out using Density Functional Theory employing the generalized gradient approximation. NMR shieldings were calculated using the Individual Gauge for Localized orbital Method. Convincing agreement was obtained between calculated and experimentally derived isotropic chemical shielding values over a broad frequency range. Shielding calculations employing the localized orbitals/local origin method resulted in nearly identical results. NMR chemical shift static powder patterns also exhibit excellent agreement with experimental values. These quantum mechanical calculations were applied to determine the extent of lignin primary structure preservation with diagenesis. Specifically, the calculations were used to assess whether inhomogeneous spectral broadening due to both functional group variation and local configurational variability may inhibit the detection of otherwise significant quantities of alkyl-aryl ethers in lignin derived geopolymers. Determination of the chemical-shielding tensor principle axis values reveals a strong correlation between anisotropy and asymmetry with local configuration effects such as dihedral rotation, phenyl group rotation, and bond angle variation. These results indicate that a range of 9 ppm in the isotropic chemical shift can be ascribed to local configuration. Consequently, an upper limit of 5% alkyl-aryl-linkages may go undetected using NMR spectroscopy on lignin-derived geopolymers at the liginite-sub-bituminous transition. It is concluded that the primary structure of lignin does not persist in kerogens even at relatively low thermal maturities.

Cody, G.D.; Saghi-Szabo, G. [Carnegie Institution of Washington, Washington, DC (United States). Geophysical Lab.] [Carnegie Institution of Washington, Washington, DC (United States). Geophysical Lab.

1999-01-01

136

Physiological, chemical and technological aspects of milk-protein-derived peptides with antihypertensive and ACE-inhibitory activity  

Microsoft Academic Search

Among the bioactive peptides derived from milk proteins, those with blood pressure-lowering effects are receiving special attention due to the prevalence and importance of hypertension in the Western population. A few antihypertensive products based on milk-protein-derived peptides with clinically proven health benefits already exist. This paper reviews the current literature on milk-derived peptides with antihypertensive effects. The structure-activity characteristics of

R. López-Fandiño; J. Otte; J. van Camp

2006-01-01

137

Rapid routes of synthesis of chemically reactive and highly radioactively labeled alpha- and beta-oligonucleotide derivatives for in vivo studies  

SciTech Connect

Development of the antisense oligonucleotide strategy for the regulation of gene expression in vivo poses several problems: the stability of oligonucleotides toward intracellular nucleases, labeling of oligonucleotides with high specific radioactivity, improvements of penetration of oligonucleotides into living cells, and enhancement of antisense action by coupling of chemically active groups. In the present paper synthesis of highly radioactively labeled (32P)- and (35S)oligonucleotide derivatives is described starting from both natural (beta) and nuclease-resistant (alpha) anomers of oligonucleotides. Conditions for preparative phosphorylation and thiophosphorylation suitable for oligonucleotides of various lengths, base composition, and anomeric forms were established. The stability of the phosphoramide bond under in vivo experimental conditions was checked. The methods of terminal phosphate chemical activation and terminal thiophosphate alkylation were applied to synthesize oligonucleotides equipped with hydrophobic, intercalating, alkylating, and photoactivatable groups. In the case of porphyrin-oligonucleotide conjugates, a series of new monofunctional porphyrin derivatives bearing a free aliphatic amino group was developed.

Boutorine, A.S.; Le Doan, T.; Battioni, J.P.; Mansuy, D.; Dupre, D.; Helene, C. (Museum National d'Histoire Naturelle, Paris (France))

1990-09-01

138

¹H, ¹³C and ¹?N chemical shift assignments of unliganded Bcl-xL and its complex with a photoresponsive Bak-derived peptide.  

PubMed

Here we report the (1)H, (13)C and (15)N resonance assignments of free Bcl-x(L) and of Bcl-x(L) in complex with an azobenzene-modified peptide derived from the BH3 domain of the pro-apoptotic Bak. The spectra suggest predominantly folded proteins; chemical shift difference analysis provides a detailed view of the reorganization occurring on peptide binding. PMID:22744789

Wysoczanski, Piotr; Mart, Robert J; Loveridge, E Joel; Williams, Christopher; Whittaker, Sara B-M; Crump, Matthew P; Allemann, Rudolf K

2013-10-01

139

Synthesis and in vitro chemical and enzymatic stability of glycosyl 3?-azido-3?-deoxythymidine derivatives as potential anti-HIV agents  

Microsoft Academic Search

New glycosyl derivatives of 3?-azido-3?-deoxythymidine (AZT) (1 and 2) were synthesized in order to improve AZT retention in the blood and to guarantee its sustained release, overcoming the necessity of multiple drug administrations. The esters synthesized (1 and 2) link AZT, by a succinyl linker, to the C-3 position of glucose and to C-6 of galactose. Furthermore, the chemical and

Francesco Bonina; Carmelo Puglia; Maria Grazia Rimoli; Lucia Avallone; Enrico Abignente; Giampiero Boatto; Maria Nieddu; Rosaria Meli; Michele Amorena; Paolo de Caprariis

2002-01-01

140

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

141

Physiological chemical and technological aspects of milk-protein-derived peptides with antihypertensive and ACE-inhibitory activity  

Microsoft Academic Search

Abstract Among the bioactive peptides derived from milk proteins, those with blood pressure-lowering effects are receiving special attention due to the prevalence,and importance,of hypertension,in the Western population. A few antihypertensive,products,based on milk-protein- derived peptides with clinically proven,health benefits already exist. This paper reviews the current literature on milk-derived peptides with antihypertensive,effects. The structure-activity characteristics of angiotensin,converting,enzyme,(ACE) inhibitory peptides,are discussed, as

R. Lo Pez-fandino; J. Otte; J. Van Camp

142

Real-time continuous characterization of secondary organic aerosol derived from isoprene epoxydiols in downtown Atlanta, Georgia, using the Aerodyne Aerosol Chemical Speciation Monitor.  

PubMed

Real-time continuous chemical measurements of fine aerosol were made using an Aerodyne Aerosol Chemical Speciation Monitor (ACSM) during summer and fall 2011 in downtown Atlanta, Georgia. Organic mass spectra measured by the ACSM were analyzed by positive matrix factorization (PMF), yielding three conventional factors: hydrocarbon-like organic aerosol (HOA), semivolatile oxygenated organic aerosol (SV-OOA), and low-volatility oxygenated organic aerosol (LV-OOA). An additional OOA factor that contributed to 33 ± 10% of the organic mass was resolved in summer. This factor had a mass spectrum that strongly correlated (r(2) = 0.74) to that obtained from laboratory-generated secondary organic aerosol (SOA) derived from synthetic isoprene epoxydiols (IEPOX). Time series of this additional factor is also well correlated (r(2) = 0.59) with IEPOX-derived SOA tracers from filters collected in Atlanta but less correlated (r(2) < 0.3) with a methacrylic acid epoxide (MAE)-derived SOA tracer, ?-pinene SOA tracers, and a biomass burning tracer (i.e., levoglucosan), and primary emissions. Our analyses suggest IEPOX as the source of this additional factor, which has some correlation with aerosol acidity (r(2) = 0.3), measured as H(+) (nmol m(-3)), and sulfate mass loading (r(2) = 0.48), consistent with prior work showing that these two parameters promote heterogeneous chemistry of IEPOX to form SOA. PMID:23638946

Budisulistiorini, Sri Hapsari; Canagaratna, Manjula R; Croteau, Philip L; Marth, Wendy J; Baumann, Karsten; Edgerton, Eric S; Shaw, Stephanie L; Knipping, Eladio M; Worsnop, Douglas R; Jayne, John T; Gold, Avram; Surratt, Jason D

2013-06-01

143

Reactivity and molecular structure of silicon-oxygen-carbon-containing films derived from organometallic chemical vapor deposition (OMCVD)  

Microsoft Academic Search

The organometallic chemical vapor deposition (OMCVD) of non-crystalline solids is an attractive method to provide surface protection. The drawback of large scale processing is the difficulty in depositing films reproducibly with long-term reliability. Hence, there is continuing research for the preparation of ceramic films, such as metal carbides, which are reliable with respect to composition and performance. The purpose of

Terence J. Clark

1996-01-01

144

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

145

Reproducible Growth of Metalorganic Chemical Vapor Deposition Derived YBa2Cu3Ox Thin Films Using Ultrasonic Gas Concentration Analyzer  

NASA Astrophysics Data System (ADS)

We report, in detail, on precursor concentration monitoring in the metalorganic chemical vapor deposition (MOCVD) of YBa2Cu3Ox (YBCO) by ultrasonic measurement and a newly developed feedback system to solve reproducibility problems. The fluctuation of the flow rate of dipivaloylmethanate (DPM) compounds has been clearly observed. We have proposed a feedback system using an ultrasonic concentration analyzer and two sets of mass flow controllers for each precursor, and have proven the validity of the operation.

Yamamoto, Shuu'ichirou; Nagata, Kouji; Sugai, Satoshi; Sengoku, Akio; Matsukawa, Yasunari; Hattori, Takeo; Oda, Shunri

1999-08-01

146

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

147

Chemically-responsive complexation of a diquaternary salt with bis(m-phenylene)-32-crown-10 derivatives and host substituent effect on complexation geometry.  

PubMed

A chemically responsive diquaternary salt with ?-extended surface was made. The host-guest complexation with chemo-responsiveness between three bis(m-phenylene)-32-crown-10 (BMP32C10) derivatives and this diquaternary salt guest was studied through the sequential addition of basic and acidic reagents (diethylamine and trifluoroacetic acid, respectively). Furthermore, the host-substituent effect on the complexation geometries of these three host-guest complexes, from taco to taco-type threaded to threaded structures by changing the substituent on BMP32C10 as shown by crystal structures, was also addressed. PMID:23320925

Yan, Xuzhou; Li, Zhengtao; Wei, Peifa; Huang, Feihe

2013-02-01

148

Design and synthesis of (S)- and (R)-?-(phenyl)ethylamine-derived NH-type ligands and their application for the chemical resolution of ?-amino acids.  

PubMed

This work presents the first chemical approach for the resolution of ?-amino acids offering the following advantages: (1) The specially designed resolving reagent is derived from ?-(phenyl)ethylamine, the most inexpensive chiral auxiliary, which can be recycled and reused, rendering the cost structure of the complete process very attractive; (2) the time-efficient two-step process can be conducted under operationally convenient conditions with virtually quantitative yields; and (3) the process can readily be adapted to large-scale use. PMID:25008025

Takeda, Ryosuke; Kawamura, Akie; Kawashima, Aki; Moriwaki, Hiroki; Sato, Tatsunori; Aceña, José Luis; Soloshonok, Vadim A

2014-08-28

149

SimShiftDB; local conformational restraints derived from chemical shift similarity searches on a large synthetic database.  

PubMed

We present SimShiftDB, a new program to extract conformational data from protein chemical shifts using structural alignments. The alignments are obtained in searches of a large database containing 13,000 structures and corresponding back-calculated chemical shifts. SimShiftDB makes use of chemical shift data to provide accurate results even in the case of low sequence similarity, and with even coverage of the conformational search space. We compare SimShiftDB to HHSearch, a state-of-the-art sequence-based search tool, and to TALOS, the current standard tool for the task. We show that for a significant fraction of the predicted similarities, SimShiftDB outperforms the other two methods. Particularly, the high coverage afforded by the larger database often allows predictions to be made for residues not involved in canonical secondary structure, where TALOS predictions are both less frequent and more error prone. Thus SimShiftDB can be seen as a complement to currently available methods. PMID:19224375

Ginzinger, Simon W; Coles, Murray

2009-03-01

150

Derivation of multipotent nestin(+)/CD271 (-)/STRO-1 (-) mesenchymal-like precursors from human embryonic stem cells in chemically defined conditions.  

PubMed

The successful establishment of stem cell-based therapies requires multipotent, immunocompatible stem cells, highly efficient strategies for direct differentiation, and most importantly, optimal culture conditions for large-scale expansion of such cell populations. Other than adult tissues, human embryonic stem cells (hESCs) represent another infinitely expansible source for mesenchymal stem cell (MSC) derivation. Here, we reproducibly derived a population of Nestin(+)/CD271(-)/STRO-1(-) mesenchymal-like precursors from hESCs (hESC-MPs) in chemically defined conditions, without requiring any serum or serum replacement of animal origin, based on a Y-27632-assisted monolayer culture system. These cells showed slim fibroblastic morphology, and satisfied the criteria of MSCs including self-renewal, the expression of multiple MSC-specific markers and the ability to differentiate into osteoblasts, adipocytes and chondrocytes. Compared with previously reported hESC-derived MSCs, our hESC-MPs were more multipotent, and could differentiate into representative derivatives of all three embryonic germ layers including mature smooth muscle cells, cardiomyocytes, functional hepatocytes and neural cells expressing various neurotransmitter phenotypes, making them an attractive cell source for regenerative medicine. PMID:21674199

Wu, Rongrong; Gu, Bin; Zhao, Xiaoli; Tan, Zhou; Chen, Liangbiao; Zhu, Jiang; Zhang, Ming

2013-03-01

151

Molecular and Chemical Characterization of the Biosynthesis of the 6-MSA-Derived Meroterpenoid Yanuthone D in Aspergillus niger.  

PubMed

Secondary metabolites in filamentous fungi constitute a rich source of bioactive molecules. We have deduced the genetic and biosynthetic pathway of the antibiotic yanuthone D from Aspergillus niger. Our analyses show that yanuthone D is a meroterpenoid derived from the polyketide 6-methylsalicylic acid (6-MSA). Yanuthone D formation depends on a cluster composed of ten genes including yanA and yanI, which encode a 6-MSA polyketide synthase and a previously undescribed O-mevalon transferase, respectively. In addition, several branching points in the pathway were discovered, revealing five yanuthones (F, G, H, I, and J). Furthermore, we have identified another compound (yanuthone X1) that defines a class of yanuthones that depend on several enzymatic activities encoded by genes in the yan cluster but that are not derived from 6-MSA. PMID:24684908

Holm, Dorte K; Petersen, Lene M; Klitgaard, Andreas; Knudsen, Peter B; Jarczynska, Zofia D; Nielsen, Kristian F; Gotfredsen, Charlotte H; Larsen, Thomas O; Mortensen, Uffe H

2014-04-24

152

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

153

Quantum chemical approach to isomerization of 1,2-dihydro-1,2-epoxybenzene and its derivatives involving hydration  

Microsoft Academic Search

The present study compares experimental values of log(104 × k0) or logkH in the isomerization of 1,2-dihydro-1,2-epoxybenzene and its derivatives with the activation parameters by the PM3 calculation in the gas phase and a simple model of hydration which includes only water molecules linking directly to the solute. The calculated results show that none of the activation parameters in the

Hidetaka Matsuzaki

1998-01-01

154

Properties of high ash char particles derived from inertinite-rich coal: 1. Chemical, structural and petrographic characteristics  

Microsoft Academic Search

An investigation was undertaken to determine the properties of high ash coal–chars derived from South African discards rich in inertinites, for the development of suitable overall reaction rate models at low temperatures (<900°C). Detailed characterisation results of the parent coal and chars prepared at 700°C and 900°C obtained from standard coal analytical methods, petrographic techniques, CCSEM image analysis and a

Raymond C. Everson; Hein W. J. P. Neomagus; Rufaro Kaitano; Rosemary Falcon; Chris van Alphen; Vivien M. du Cann

2008-01-01

155

Chemical abundances of planetary nebulae from optical recombination lines - II. Abundances derived from collisionally excited lines and optical recombination lines  

NASA Astrophysics Data System (ADS)

In Paper I, we presented spectrophotometric measurements of emission lines from the ultraviolet (UV) to the far-infrared for 12 Galactic planetary nebulae (PNe) and derived nebular thermal and density structures using a variety of plasma diagnostics. The measurements and plasma diagnostic results are used in the current paper to determine elemental abundances in these nebulae. Abundance analyses are carried out using both strong collisionally excited lines (CELs) and weak optical recombination lines (ORLs) from heavy element ions. Assuming electron temperatures and densities derived from HI recombination spectra (line and continuum), we are able to determine the ORL C abundance relative to hydrogen for all the PNe in our sample, N and O abundances for 11 of them and Ne abundances for nine of them. In all cases, ORL abundances are found to be systematically higher than the corresponding values deduced from CELs. In NGC 40, the discrepancy between the abundances derived from the two types of emission line reaches a factor of 17 for oxygen. For the other 10 PNe, the discrepancies for oxygen vary from 1.6 to 3.1. In general, collisionally excited infrared fine-structure lines, which have excitation energies less than 103 K and consequently emissivities that are insensitive to electron temperature and temperature fluctuations, yield ionic abundances comparable to those derived from optical/UV CELs. For a given nebula, the discrepancies between the ORL and CEL abundances are of similar magnitude for different elements. In other words, relative abundance ratios such as C/O, N/O and Ne/O deduced from the traditional method based on strong CELs are comparable to those yielded by ORLs, for a wide range of ORL to CEL oxygen abundance ratios, varying from near unity to over a factor of 20. We have also determined ORL abundances relative to hydrogen for the third-row element magnesium for 11 nebulae in our sample. In strong contrast to the cases for second-row elements, Mg abundances derived from the MgII 3d-4f ?4481 ORL are nearly constant for all the PNe analysed so far and agree within the uncertainties with the solar photospheric value. In accordance with results from previous studies, the ORL to CEL abundance ratio is correlated with the difference between the electron temperatures derived from the [OIII] forbidden-line ratio, on the one hand, and from the hydrogen recombination Balmer discontinuity, on the other. We find that the discrepancy between the ORL and CEL abundances is correlated with nebular absolute diameter, surface brightness, the electron density derived from [SII] CELs, and excitation class. The results confirm that the dichotomy of temperatures and heavy elemental abundances determined from the two types of emission line, which has been widely observed in PNe, is a strong function of nebular evolution, as first pointed out by Garnett and Dinerstein. Our analyses show that temperature fluctuations and/or density inhomogeneities are incapable of explaining the large discrepancies between the heavy elemental abundances and electron temperatures determined from the two types of emission line. Our analyses support the bi-abundance model of Liu et al., who have proposed that PNe contain another previously unseen component of ionized gas which, highly enriched in heavy elements, has an electron temperature of <~103 K and emits strongly in recombination lines but not in CELs. Our determinations of low average emission temperatures from the observed line intensity ratios of HeI and OII ORLs lend further support to this scenario.

Liu, Y.; Liu, X.-W.; Barlow, M. J.; Luo, S.-G.

2004-10-01

156

Influence of the environment on kinetics and electronic structure of asymmetric azobenzene derivatives — experiment and quantum-chemical calculations  

NASA Astrophysics Data System (ADS)

The kinetics of thermally driven cis- trans isomerisation of asymmetrically substituted azobenzenes dissolved in solvents of various polarities was measured spectrophotometrically. The solvatochromic effect was observed in 4-nitro-4'-aminoazobenzene as well as in 4-nitro-4'methoxyazobenzene. The experiment has been supplemented with quantum-chemical calculations. The solvent effect was taken into account using the quantum-mechanical Langevin dipoles/Monte Carlo (QM/LD/MC) approach. Calculations of first-order hyperpolarizability tensors of investigated molecules have been performed within a sum-over-states (SOS) method. Both methods were implemented in the all-valence method, GRINDOL.

Matczyszyn, K.; Bartkowiak, W.; Leszczynski, J.

2001-05-01

157

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

PubMed Central

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

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

2009-01-01

158

Influence of decomposition on chemical properties of plant- and manure-derived dissolved organic matter and sorption to goethite.  

PubMed

Sorption of dissolved organic matter (DOM) plays an important role in maintaining the fertility and quality of soils in agricultural ecosystems. Few studies have examined the effects of decomposition on DOM sorption and chemical characteristics. This study investigated the sorption to goethite (alpha-FeOOH) of fresh and decomposed hydrophilic (HPL) and hydrophobic (HPB) DOM fractions extracted from the shoots and roots of crimson clover (Trifolium incarnatum L.), corn (Zea mays L.), soybean [Glycine max (L.) Merr.], hairy vetch (Vicia villosa L.), and dairy and poultry manures. Sorption was positively related to apparent molecular weight (MWAP), aromaticity as measured by absorptivity at 280 nm, and phenolic acid content. A 10-d laboratory microbial decomposition of the source organic matter generally increased the sorption of the extracted DOM onto goethite. The decomposition effect on sorption was greater for the HPL fractions than for the HPB fractions. There was a decrease in the MWAP values of the DOM samples following sorption to goethite. In many cases the reduction in MWAP was large, indicating a strong preference by goethite for the higher MWAP DOM fractions. The results of this laboratory-based research demonstrate that microbial processes affect the chemical characteristics of DOM which may affect the distribution of soil organic C pools. PMID:17215221

Hunt, James F; Ohno, Tsutomu; He, Zhongqi; Honeycutt, C Wayne; Dail, D Bryan

2007-01-01

159

Enhanced chemopreventive activity of hydroxytyrosol on HL60 and HL60R cells by chemical conversion into thio derivatives.  

PubMed

Thio derivatives of hydroxytyrosol containing thiol, thioacetate and disulfide functionalities were synthesized from natural hydroxytyrosol (3,4-DHPEA) via 3,4-dihydroxyphenethyl halides. These compounds, containing the combination of catechol moiety and divalent sulfur functions, were tested for the pro-apoptotic and anti-proliferative activities on both parental HL60 and multi-drug resistant HL60R cells. It was found that all synthesized compounds were more effective than 3,4-DHPEA in inducing apoptosis on HL60R cells, and that the hydroxytyrosol disulfide was the most active pro-apoptotic and anti-proliferative compound on both HL60 and HL60R cells. Different from 3,4-DHPEA, all thio derivatives of hydroxytyrosol induced apoptosis by a mechanism not involving the release of H(2)O(2) in the culture medium. The data on HL60R cells suggest that these compounds could be able to reverse the resistance toward the most common drugs in cancer therapy. PMID:23313620

Sepporta, Maria Vittoria; López-García, M Ángeles; Fabiani, Roberto; Maya, Inés; Fernández-Bolaños, José G

2013-03-12

160

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

161

Influence of feedstock chemical composition on product formation and characteristics derived from the hydrothermal carbonization of mixed feedstocks.  

PubMed

As the exploration of the carbonization of mixed feedstocks continues, there is a distinct need to understand how feedstock chemical composition and structural complexity influence the composition of generated products. Laboratory experiments were conducted to evaluate the carbonization of pure compounds, mixtures of the pure compounds, and complex feedstocks comprised of the pure compounds (e.g., paper, wood). Results indicate that feedstock properties do influence carbonization product properties. Carbonization product characteristics were predicted using results from the carbonization of the pure compounds and indicate that recovered solids energy contents are more accurately predicted than solid yields and the carbon mass in each phase, while predictions associated with solids surface functional groups are more difficult to predict using this linear approach. To more accurately predict carbonization products, it may be necessary to account for feedstock structure and/or additional feedstock properties. PMID:24907571

Lu, Xiaowei; Berge, Nicole D

2014-08-01

162

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

163

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

164

Combined experimental and quantum chemical investigation of chiroptical properties of nicotinamide derivatives with and without intramolecular cation-pi interactions.  

PubMed

The circular dichroism (CD) spectra of neutral and cationic nicotinamide derivatives were experimentally examined in solution and in the solid state to show dramatic differences in the two phases and appreciable dependence on temperature and solvent. The CD spectrum of neutral nicotinamide 1 in solution was reproduced theoretically by averaging the theoretical spectra calculated for all of the extended and folded conformers (s-trans-G(+), s-cis-G(+), s-trans-T, and s-cis-T) weighted by their population. The preference for the folded, over the extended, conformers in less polar solvent was indicated by the calculation and confirmed experimentally by the analysis of specific rotations. Theoretical CD spectrum calculated for the conformer found in the X-ray structural analysis (s-cis-T) well reproduced the experimental CD spectrum measured in the solid state. Introducing cation-pi interactions by N-methylation of 1 to give 1-Me(+) led to dramatic changes in CD spectrum. Nevertheless, the experimental CD spectrum of 1-Me(+) was well reproduced by averaging the theoretical spectra calculated for a pair of most stable conformers (s-cis-G(+) and s-trans-G(+)) of 1-Me(+). The CD spectrum calculated for the s-trans-G(+) conformer, which was found in the X-ray crystallographic analysis, did not agree with the experimental one. The theoretical spectra were better reproduced in general by the more sophisticated RI-CC2 method, but the conventional TD-DFT method also gave acceptable results. This allowed us to successfully calculate the larger derivative 2-Me(+), for which the RI-CC2 method was not practically applicable. These results show that the structure/conformation may vary with the conditions employed (e.g., by altering the solvent or phase) and thus the experimental analysis under the identical condition is essential for a serious structural study. The present study on a series of nicotinamide derivatives 1, 1-Me(+), and 2-Me(+) with and without cation-pi interactions demonstrates that the combination of experimental and theoretical chiroptical methods is capable of providing reliable structural/conformational information in solution phase, which is complementary to the X-ray crystallographic structure in the solid state. PMID:19719320

Shimizu, Akinori; Mori, Tadashi; Inoue, Yoshihisa; Yamada, Shinji

2009-07-30

165

Growth Behavior of an Adsorbed Monolayer from a Benzophenone-Containing Trimethoxysilane Derivative on a Fused Silica Surface for Nanoimprint Molds by Chemical Vapor Surface Modification  

NASA Astrophysics Data System (ADS)

The formation of a monolayer from a benzophenone-containing trimethoxysilane derivative was studied to understand the growth behavior of an antisticking layer from a trimethoxysilane derivative with an alkyl long tail often used as an antisticking layer in nanoimprint lithography. An adsorbed monolayer was formed from 4-{[(3-trimethoxysilyl)propyl]oxy}benzophenone on a fused silica surface by chemical vapor surface modification (CVSM). The growth behavior of the adsorbed monolayer was monitored by UV-visible spectroscopy, and the results were compared with those obtained by contact angle measurement for water and atomic force microscopy. The monolayer formation was confirmed with absorption spectra showing a characteristic absorption band derived from a benzophenone moiety. Changes in contact angle and absorbance with an increase in CVSM period suggested that the monolayer formation was completed in 2 h. The period of 2 h suitable for CVSM was also supported by atomic force microscopy topographic images. These results suggested that the monolayer growth comprises the following three steps: the surface adsorption, condensation and packing, and excess adsorption steps.

Shoichi Kubo,; Masaru Nakagawa,

2010-06-01

166

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.

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

2013-01-01

167

40 CFR 721.1820 - Bisphenol derivative.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Bisphenol derivative. 721.1820 Section 721...Chemical Substances § 721.1820 Bisphenol derivative. (a) Chemical substance...chemical substance identified generically as bisphenol derivative (PMN No....

2009-07-01

168

40 CFR 721.1820 - Bisphenol derivative.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Bisphenol derivative. 721.1820 Section 721...Chemical Substances § 721.1820 Bisphenol derivative. (a) Chemical substance...chemical substance identified generically as bisphenol derivative (PMN No....

2013-07-01

169

Differences between amine- and phosphine-boranes: synthesis, photoelectron spectroscopy, and quantum chemical study of the cyclopropylic derivatives.  

PubMed

Borane complexes of aziridine, phosphirane, cyclopropylamine, cyclopropylphosphine, cyclopropylmethylamine, and cyclopropylmethylphosphine have been prepared by the reaction at low temperatures of a borane complex or diborane on the free phosphine or amine. The products characterized by NMR spectroscopy and mass spectrometry have then been investigated by photoelectron spectroscopy and B3LYP/aug-cc-pVTZ quantum chemical study. The complexation led to rotamers with structures similar to the ones of the corresponding free systems. The main geometry change with the complexation is the P-C bond elongation and the N-C bond shortening, which can be rationalized by the charge transfer attached to the electron donation. The calculated relative stability order of the conformers changes with the complexation only in the case of cyclopropylamine. The calculated complexation energies are higher for the amines, in accord with the differences observed in the flash vacuum thermolysis of methylamine-, methylphosphine-, and aziridine-borane. The photoelectron spectra indicate essential differences between the amines and phosphines toward borane complexation. The dative bond is more stable in the studied amine-boranes than in phosphine-boranes, while the sigma(B-H) orbitals are more stable in the latter compounds. The enthalpy of the hydrogen release reaction of aziridine-borane is almost thermoneutral, indicating the potential of this complex as recyclable hydrogen storage material. PMID:20433190

Németh, Balázs; Khater, Brahim; Guillemin, Jean-Claude; Veszprémi, Tamás

2010-06-01

170

Atmospheric pressure chemical vapor infiltration (CVI) for the preparation of biomorphic SiC ceramics derived from paper.  

PubMed

Chemical Vapor Infiltration of biological structures such as paper is used here to produce biomorphic SiC ceramics with high temperature resistance. The biological substrate materials are infiltrated with tetramethylsilane (TMS) at atmospheric pressure and elevated temperatures of 790 degrees C. A simple tube furnace (hot-wall reactor) is used for the infiltration process. As result, porous SiC-ceramics are grown which are around 20% smaller and 70% lighter than the initial substrates. This can be explained by the pyrolytic reaction of the substrates while heating them up to 790 degrees C, which is necessary for the infiltration process. Nevertheless, besides the shrinking of the substrates the geometrical form remains nearly unchanged. The resulting materials were heated up to 1000 degrees C in oxygen atmosphere in order to analyze their resistance against oxidation. After this treatment, all of them were still mechanically stable and of unchanged shape while a further mass loss was observed. This confirms the high temperature stability of the prepared materials. PMID:22097596

Pflitsch, Christian; Curdts, Benjamin; Atakan, Burak

2011-09-01

171

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

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

172

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

173

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

USGS Publications Warehouse

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

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

1978-01-01

174

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

175

Antitumour polycyclic acridines. Part 4. Physico-chemical studies on the interactions between DNA and novel tetracyclic acridine derivatives.  

PubMed

The non-covalent interactions between a series of new tetracyclic acridine derivatives (5-11) and DNA have been studied by spectrophotometric analysis, fluorescences quenching, thermal denaturation, and circular and linear dichroism. In order to compare the extent of the DNA binding by compounds 5-11 in their neutral and cationic forms, all experiments were conducted at pH 7.4 (physiological pH) and 5.0. The results indicated that compounds 5-11 are strong DNA-binding ligands with DNA affinities comparable to that of m-AMSA (1) or even higher. They showed a stronger DNA binding activity at pH 5.0 as a result of the N-protonation of the pyridoacridine aromatic chromophore. Ethidium-DNA fluorescence assays showed an A-T base pair preference of the binding distinguishing these novel compounds from simple acridines which show a slight G-C base pair preference. Circular and linear dichroism studies indicated that the drugs bind to DNA by undergoing intercalation inside the duplex macromolecule at high DNA:drug ratios and revealed alternative binding modes at low DNA:drug ratios. PMID:9702209

Giménez-Arnau, E; Missailidis, S; Stevens, M F

1998-07-01

176

Quantum chemical insights into the aggregation induced emission phenomena: a QM/MM study for pyrazine derivatives.  

PubMed

There have been intensive studies on the newly discovered phenomena called aggregation induced emission (AIE), in contrast to the conventional aggregation quenching. Through combined quantum mechanics and molecular mechanics computations, we have investigated the aggregation effects on the excited state decays, both via radiative and nonradiative routes, for pyrazine derivatives 2,3-dicyano-5,6-diphenylpyrazine (DCDPP) and 2,3-dicyanopyrazino phenanthrene (DCPP) in condensed phase. We show that for DCDPP there appear AIE for all the temperature, because the phenyl ring torsional motions in gas phase can efficiently dissipate the electronic excited state energy, and get hindered in aggregate; while for its "locked"-phenyl counterpart, DCPP, theoretical calculation can only give the normal aggregation quenching. These first-principles based findings are consistent with recent experiment. The primary origin of the exotic AIE phenomena is due to the nonradiative decay effects. This is the first time that AIE is understood based on theoretical chemistry calculations for aggregates, which helps to resolve the present disputes over the mechanism. PMID:22622704

Wu, Qunyan; Deng, Chunmei; Peng, Qian; Niu, Yingli; Shuai, Zhigang

2012-09-01

177

Soluble sulfur species extracted from coal by chemical leaching. [MS thesis; mineral and coal-derived pyrite; 114 references  

SciTech Connect

The nature of the soluble sulfur-containing reaction products from the desulfurization of pyrite was studied. The rate of oxydesulfurization of the two varieties of pyrite was studied under the leaching conditions of the Ames process. Concentrations of soluble sulfur species were determined for oxydesulfurization using leach solutions of sodium carbonate, sodium bicarbonate, distilled water, and dilute sulfuric acid and for alkaline leaching without oxygen using sodium carbonate. Mineral grade pyrite was found to be much less reactive towards oxydesulfurization than coal-derived pyrite, although the mechanism of sulfur removal was apparently the same. The sulfur containing products of oxydesulfurization were found to be thiosulfate, sulfite, and sulfate for alkaline leach solutions, and elemental sulfur and sulfuric acid when neutral or acidic solutions were used. For the Ames process, thiosulfate was usually the major sulfur containing product, although oxidation to sulfite and sulfate was found to take place. Oxidation of thiosulfate did not occur with oxygen alone, but did occur in the presence of oxygen and partially reacted pyrite. Higher temperatures and higher oxygen partial pressures favored formation of sulfate at the expense of both thiosulfate and sulfite. With neutral and acidic leach solutions, sulfuric acid accounted for most of the sulfur, although measurable quantities of elemental sulfur were present.Higher oxygen partial pressures and higher temperatures favored the formation of sulfuric acid at the expense of elemental sulfur. Pyrite oxidized faster under alkaline conditions than under neutral or acidic conditions. Pyrite was also leached at high temperatures in a sodium carbonate solution in the absence of oxygen.

Stephenson, M.D.

1982-07-01

178

Structure determination of slowly exchanging conformers in solution using high-resolution NMR, computational modeling and DFT-GIAO chemical shielding: application to an erythronolide A derivative.  

PubMed

We discuss and demonstrate the potential of HSQC-TOCSY and HSQC-NOESY experiments to offer solutions for overlap problems in COSY and NOESY spectra, leading to improved signals that can be unambiguously assigned to individual carbons. Direct comparison of experimental (1)H and (13)C chemical shielding with density functional theory (DFT)-calculated values are uninformative; in contrast, the relative differences in experimental shielding between pairs of molecules correlates well with the relative differences in DFT-GIAO shielding for the computed lowest energy conformers. A detailed application of both experimental and theoretical techniques is illustrated for slowly exchanging conformers of an erythronolide A derivative, which demonstrates that structure determination can strongly benefit from the interplay between experiment and theory. PMID:19591195

Muri, Dieter; Corminboeuf, Clémence; Carreira, Erick M; Jeannerat, Damien

2009-11-01

179

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

NASA Astrophysics Data System (ADS)

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

Wang, Peng; Lu, Jennifer; Zhou, Otto

2008-05-01

180

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

181

Common host-derived chemicals increase catches of disease-transmitting mosquitoes and can improve early warning systems for Rift Valley fever virus.  

PubMed

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 CO(2)-baited CDC trap without a light bulb doubled to tripled trap captures compared to control traps baited with CO(2) 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

182

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.

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

2013-01-01

183

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

184

Sequential identification of model parameters by derivative double two-dimensional correlation spectroscopy and calibration-free approach for chemical reaction systems.  

PubMed

A sequential identification approach by two-dimensional (2D) correlation analysis for the identification of a chemical reaction model, activation, and thermodynamic parameters is presented in this paper. The identification task is decomposed into a sequence of subproblems. The first step is the construction of a reaction model with the suggested information by model-free 2D correlation analysis using a novel technique called derivative double 2D correlation spectroscopy (DD2DCOS), which enables one to analyze intensities with nonlinear behavior and overlapped bands. The second step is a model-based 2D correlation analysis where the activation and thermodynamic parameters are estimated by an indirect implicit calibration or a calibration-free approach. In this way, a minimization process for the spectral information by sample-sample 2D correlation spectroscopy and kinetic hard modeling (using ordinary differential equations) of the chemical reaction model is carried out. The sequential identification by 2D correlation analysis is illustrated with reference to the isomeric structure of diphenylurethane synthesized from phenylisocyanate and phenol. The reaction was investigated by FT-IR spectroscopy. The activation and thermodynamic parameters of the isomeric structures of diphenylurethane linked through a hydrogen bonding equilibrium were studied by means of an integration of model-free and model-based 2D correlation analysis called a sequential identification approach. The study determined the enthalpy (?H = 15.25 kJ/mol) and entropy (T?S = 13.20 kJ/mol) of C?O···H hydrogen bonding of diphenylurethane through direct calculation from the differences in the kinetic parameters (??(‡)H, -T??(‡)S) at equilibrium in the chemical reaction system. PMID:22924791

Spegazzini, Nicolas; Siesler, Heinz W; Ozaki, Yukihiro

2012-10-01

185

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.

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

2014-01-01

186

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

PubMed

F62 LOS of Neisseria gonorrhoeae consists of two major LOS components; the higher and smaller molecular weight (MW) components were recognized by MAbs 1-1-M and 3F11 respectively. Base-line separation of the two major oligosaccharide (OS) components from F62 LOS was achieved by Bio-Gel P-4 chromatography after dephosphorylation of the OS mixture. The structures of the two major OSs were studied by chemical, enzymatic, and 2D NMR methods [double quantum filtered COSY (DQF-COSY), delayed COSY (D-COSY), homonuclear Hartmann-Hahn spectroscopy (HOHAHA), pure-absorption 2D NOE NMR] as well as methylation followed by GC/MS analysis. The OS component derived from the MAb 1-1-M defined LOS component was determined to have a V3-(beta-N-acetylgalactosaminyl)neolactotetraose structure (GalNAc is beta 1----3-linked to a neolactotetraose) at one of its nonreducing termini as shown below. The above pentaose is linked to a branched diheptose-KDO core in which a GlcNAc is alpha-linked. The OS component derived from the MAb 3F11 defined LOS component did not have a GalNAc residue. The rest of its structure was identical to that of the OS-1, and a neolactotetraose is exposed at its nonreducing terminus. [formula: see text] PMID:1931980

Yamasaki, R; Bacon, B E; Nasholds, W; Schneider, H; Griffiss, J M

1991-10-29

187

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

188

The interplay between hydrogen bonding and ?-? stacking interactions in the crystal packing of N1-thyminyl derivatives, and implications for the photo-chemical [2? + 2?]-cycloaddition of thyminyl compounds.  

PubMed

The solid-state photo-chemical dimerisation of thyminyl derivatives occurs when two thyminyl units are aligned in such a way that the olefinic moieties are separated by a distance of less than 4.2 Å. When irradiated with >270 nm UV, the thyminyl olefinic groups undergo [2? + 2?]-cycloaddition to form a dimeric cyclobutane derivative. However, the design and execution of [2? + 2?]-cycloaddition reactions can be challenging due to the requirement to produce molecular crystals with the necessary olefinic alignment. In this investigation, the crystallographic and solid-state photo-chemical reactions of six N1-thyminyl derivatives are studied. Only one derivative, thyminyl propanamide (), was found to undergo [2? + 2?]-cycloaddition in the crystalline state. As such, quantum chemical methods were employed to study the photo-chemical transition states of the derivatives, as well as the strengths of typical intermolecular interactions that were observed in their crystal structures (such as ?-? stacking between the thyminyl rings, Watson and Crick style hydrogen bonding and hydrogen bonding between functional groups of N1 substituents). These results were used to rationalise the solid-state photo-reactivity of more complex bis-thyminyl monomers. PMID:22952024

Johnston, Priscilla; Izgorodina, Ekaterina I; Saito, Kei

2012-12-01

189

The epigenetic promotion of osteogenic differentiation of human adipose-derived stem cells by the genetic and chemical blockade of histone demethylase LSD1.  

PubMed

Human adipose-derived stem cells (hASCs) are a highly attractive source in bone tissue engineering. It has become increasingly clear that chromatin regulators play an important role in cell fate determination. However, how osteogenic differentiation of hASCs is controlled by epigenetic mechanisms is not fully understood. Here we use genetic tools and chemical inhibitors to modify the epigenetic program of hASCs and identify lysine-specific demethylase 1 (LSD1), a histone demethylase that specifically catalyzes demethylation of di- and mono- methyl histone H3 lysine 4 (H3K4me2/1), as a key regulator in osteogenic differentiation of hASCs. Specifically, we demonstrated that genetic depletion of LSD1 with lentiviral strategy for gene knockdown promoted osteogenic differentiation of hASCs by cell studies and xenograft assays. At the molecular level, we found that LSD1 regulates osteogenesis-associated genes expression through its histone demethylase activity. Significantly, we demonstrated LSD1 demethylase inhibitors could efficiently block its catalytic activity and epigenetically boost osteogenic differentiation of hASCs. Altogether, our study defined the functional and biological roles of LSD1 and extensively explored the effects of its enzymatic activity in osteogenic differentiation of hASCs. A better understanding of how LSD1 influences on osteogenesis associated epigenetic events will provide new insights into the modulation of hASCs based cell therapy and improve the development of bone tissue engineering with epigenetic intervention. PMID:24794925

Ge, Wenshu; Liu, Yunsong; Chen, Tong; Zhang, Xiao; Lv, Longwei; Jin, Chanyuan; Jiang, Yong; Shi, Lei; Zhou, Yongsheng

2014-07-01

190

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

191

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

SciTech Connect

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.

Brothers, Michael C [University of Illinois, Urbana-Champaign; Nesbitt, Anna E [University of Illinois, Urbana-Champaign; Hallock, Michael J [University of Illinois, Urbana-Champaign; Rupasinghe, Sanjeewa [University of Illinois, Urbana-Champaign; Tang, Ming [University of Illinois, Urbana-Champaign; Harris, Jason B [ORNL; Baudry, Jerome Y [ORNL; Schuler, Mary A [University of Illinois, Urbana-Champaign; Rienstra, Chad M [University of Illinois, Urbana-Champaign

2011-01-01

192

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

SciTech Connect

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

Chang, C.L.; Fogler, H.S. (Univ. of Michigan, Ann Arbor, MI (United States))

1994-06-01

193

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

SciTech Connect

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

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

2010-01-01

194

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.

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

2014-01-01

195

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

196

Asymmetric reduction of steroidal 20-ketones: chemical synthesis of corticosteroid derivatives containing the 20 alpha, 21-diol and 17 alpha, 20 alpha, 21-triol side chains.  

PubMed

A method is presented for the chemical synthesis of corticosteroid derivatives containing the 20 alpha, 21-diol and 17 alpha, 20 alpha, 21-triol side chains. The ketol side chains of cortisol, corticosterone, 11-deoxycortisol, and 11-deoxycorticosterone were reduced at C-20 with sodium borohydride in a two-phase system consisting of aqueous calcium chloride and an organic phase of chloroform or ethyl acetate. Stereoselectivity of reduction was 92% alpha-oriented for cortisol and 79% alpha-oriented for 11-deoxycortisol at -27 degrees. The 20 alpha-form diminished relative to the 20 beta-form with increasing temperature. For the 17-deoxy steroids, reduction to the 20 alpha-form was 23% for 11-deoxycorticosterone and 41% for corticosterone. The 20 alpha/20 beta ratios of 17-deoxy steroids were unchanged between 0 degree and -27 degrees. Calcium ions increased the solubility of corticosteroids in the aqueous phase. We propose that calcium ions affect the stereochemistry of reduction by forming a bidentate complex with the side chains of 17 alpha-hydroxy steroids, fixing them in an orientation favorable to 20 alpha-reduction, and by altering the phase partition of the steroids. PMID:6680932

Han, C A; Monder, C

1983-12-01

197

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

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

2014-03-01

198

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

199

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

200

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

NASA Astrophysics Data System (ADS)

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

Ryan, Jeffrey

2014-05-01

201

40 CFR 721.10172 - Alkylamide derivative (generic).  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

202

A method to relate chemical accident properties and expert judgements in order to derive useful information for the development of Environment-Accident Index  

Microsoft Academic Search

The environment consists of a variety of different compartments and processes that act together in a complex system that complicate the environmental risk assessment after a chemical accident. The Environment-Accident Index (EAI) is an example of a tool based on a strategy to join the properties of a chemical with site-specific properties to facilitate this assessment and to be used

Åsa Scott Andersson; Mats Tysklind; Ingrid Fängmark

2007-01-01

203

The comparison of surface characteristics, physico-chemical and biological properties of 304 stainless steel coated by melt-derived and sol–gel-derived 45S5 bioglass for orthopedic applications  

Microsoft Academic Search

The ability of 45S5 bioglass to form a bond to living bone tissue and stimulate bone-cell proliferation may be different for melt- and sol–gel-derived samples. In this research, the differences in corrosion resistance, bioactivity and physical properties between the melt- and sol–gel-derived 45S5 bioglass coated on the surface of austenitic 304 stainless steel (SS) as a dental and orthopedic metallic

Ali Pedram; S. Morteza Naghib; Amin Feizpour; Mojtaba Ansari

204

Use of nuclear stiffness in search for a maximum hardness principle and for the softest states along the chemical reaction path: a new formula for the energy third derivative gamma.  

PubMed

Nuclear stiffness, expressed as a hardness derivative, appears to be a good measure of the slope of global hardness. The authors analyze molecular states for which hardness has a maximum value. Maximum hardness principle (MHP) has been discussed. At the ground state hardness function does not obtain a maximum value versus spatial coordinates within a constant number of electrons (N), but is so within constant chemical potential (mu) constraint. The authors apply this feature to evaluate an energy third derivative (gamma). MHP has been analyzed via symmetry considerations of nuclear stiffness and nuclear reactivity. Nuclear stiffness has been also applied to study the hardness profile for a chemical reaction. In this case, the authors seek molecular states for which hardness is at a minimum. They have examined systems for which they have recently obtained regional chemical potentials [P. Ordon and A. Tachibana, J. Mol. Model. 11, 312 (2005); J. Chem. Sci. 117, 583 (2005)]. The transition state is found not to be the softest along the chemical reaction path. Nuclear stiffness reflects well the softest conformation of a molecule, which has been found independently along the intrinsic reaction coordinate profile. Electronic energy-density [A. Tachibana, J. Mol. Mod. 11, 301 (2005)] has been used to visualize the reactivity difference between the softest state and the transition state. PMID:17600412

Ordon, Piotr; Tachibana, Akitomo

2007-06-21

205

Quantum Mechanical Studies on Chemical Reactivity and Ballistic Chemistry. VI. Literature Review on the Relationship between Structure and Reactivity in Isomeric Tetrazole Derivatives.  

National Technical Information Service (NTIS)

As part of a program of molecular orbital calculations on the chemistry of compounds of explosive and propellant interest, a review and comparison of published reactivity differences among isomeric 1- and 2-substituted tetrazole derivatives is given. It i...

M. A. Schroeder

1975-01-01

206

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

2010-03-01

207

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

EPA Science Inventory

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

208

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

209

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

210

Validity of Methods to Predict the Respiratory Sensitizing Potential of Chemicals: A Study with a Piperidinyl Chlorotriazine Derivative That Caused an Outbreak of Occupational Asthma  

Microsoft Academic Search

A piperidinyl chlorotriazine (PCT) derivative, used as a plastic UV-stabilizer, caused an outbreak of occupational asthma. We verified, in BALB\\/c mice, the sensitizing potential of PCT in comparison to a known respiratory sensitizer (toluene diisocya- nate (TDI)) and a known dermal sensitizer (oxazolone), using three different methods in order to evaluate the validity of current models of sensitization. These included

Jeroen A. J. Vanoirbeek; Cindy Mandervelt; Albert R. Cunningham; Peter H. M. Hoet; Haiyan Xu; Hadewijch M. Vanhooren; Benoit Nemery

2003-01-01

211

Studies on cardiac ingredients of plants. VII: Chemical transformation of proscillaridin by means of the Diels-Alder reaction and biological activities of its derivatives.  

PubMed

The Diels-Alder reactions of a cardiac glycoside, proscillaridin (1), with some dienophiles were investigated. The reaction of 1 with alkenes such as methyl vinyl ketone and methyl acrylate afforded 3-oxo-2-oxabicyclo[2.2.2]oct-7-enes (2-5) and para-substituted benzene derivatives (6 and 7), while 1 reacted with alkynes (3-butyn-2-one, methyl propiolate) to yield para- or meta-substituted benzene derivatives (6-9). The biological activities of the resulting derivatives were evaluated by the use of isolated guinea-pig papillary muscle preparations and Na+,K(+)-adenosine triphosphatase (ATPase) preparation from dog kidney. Among the proscillaridin derivatives, compounds 4 and 7 moderately inhibited Na+,K(+)-ATPase activity. Furthermore, the concentration range of 7 over which its positive inotropic effect on guinea-pig papillary muscle preparations, increased from 5% to 95% of maximum was broader than that of 1, i.e., concentration dependency was maintained over a greater range of concentration. PMID:1839142

Murakami, N; Tanase, T; Nagai, S; Sato, Y; Ueda, T; Sakakibara, J; Ando, H; Hotta, Y; Takeya, K

1991-08-01

212

New modified ?-cyclodextrin derivatives as detoxifying agents of chemical warfare agents (II). In vitro detoxification of cyclosarin (GF): general screening and toxicokinetic aspects of OP scavengers.  

PubMed

As standard therapy of intoxication with organophosphorus (OP) compounds is still insufficient, developing new treatment strategies is urgently required. For evaluating potential of OP detoxification of several compounds correctly, different toxicodynamic impact of OP enantiomers has to be considered thoroughly. It has already been demonstrated that ?-cyclodextrin (?-CD) derivatives with attached nucleophilic substituent iodosobenzoic acid (IBA) can be regarded as potent OP scavengers due to an accelerating effect on decay of different OP. Herein, six CD derivatives permethylated or not on CD torus as well as differently attached nucleophilic substituent IBA derivative were investigated regarding detoxification of GF as an OP model substance. Acceleration of GF detoxification could be detected for all compounds with highest rate constants for propylene chain linked nucleophilic substituents on CD derivative. In addition, fast initial binding of GF on CD could be observed and is ascribed to formation of CD complexes. Furthermore, terminal plateau phase was detected of about 1% of each enantiomer reflecting the necessity of a quantitative determination at low concentrations. Moreover, this molecular depot formation may represent an additional detoxification pathway for OP. PMID:23201438

Müller, Susanne; Estour, François; Kalakuntla, Raman Kumar; Le Provost, Romain; Lafont, Olivier; Worek, Franz; Thiermann, Horst; Reiter, Georg

2013-02-01

213

Plakilactones G and H from a marine sponge. Stereochemical determination of highly flexible systems by quantitative NMR-derived interproton distances combined with quantum mechanical calculations of 13C chemical shifts  

PubMed Central

Summary In this paper the stereostructural investigation of two new oxygenated polyketides, plakilactones G and H, isolated from the marine sponge Plakinastrella mamillaris collected at Fiji Islands, is reported. The stereostructural studies began on plakilactone H by applying an integrated approach of the NOE-based protocol and quantum mechanical calculations of 13C chemical shifts. In particular, plakilactone H was used as a template to extend the application of NMR-derived interproton distances to a highly flexible molecular system with simultaneous assignment of four non-contiguous stereocenters. Chemical derivatization and quantum mechanical calculations of 13C on plakilactone G along with a plausible biogenetic interconversion between plakilactone G and plakilactone H allowed us to determine the absolute configuration in this two new oxygenated polyketides.

Di Micco, Simone; Zampella, Angela; D'Auria, Maria Valeria; Festa, Carmen; De Marino, Simona; Riccio, Raffaele

2013-01-01

214

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

NASA Astrophysics Data System (ADS)

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

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

2005-06-01

215

Spatiotemporal gradients in aerosol radiative forcing and heating rate over Bay of Bengal and Arabian Sea derived on the basis of optical, physical, and chemical properties  

Microsoft Academic Search

Spatiotemporal heterogeneity in aerosol radiative forcing and heating rate have been studied over Bay of Bengal and Arabian Sea during premonsoon (March-May 2006) using aerosol optical depth (AOD), total mass, aerosol chemical composition, and radiative transfer model. Mean 0.5 mum AOD over Bay of Bengal and Arabian Sea is 0.36 and 0.25, respectively. Water-soluble aerosols, sea salt, and mineral dust

Sumita Kedia; S. Ramachandran; Ashwini Kumar; M. M. Sarin

2010-01-01

216

Application of the chemical vapor infiltration and reaction (CVI-R) technique for the preparation of highly porous biomorphic SiC ceramics derived from paper  

Microsoft Academic Search

Chemical vapor infiltration and reaction (CVI-R) is used to produce biomorphic high porous SiC ceramics based on biological structures such as paper. The paper fibers are first converted into a biocarbon (Cb) template by a carbonization step. In a second step methyltrichlorosilane (MTS) in excess of hydrogen is infiltrated into the Cb-template by CVI technique, depositing a Si\\/SiC layer around

Daniela Almeida Streitwieser; Nadja Popovska; Helmut Gerhard; Gerhard Emig

2005-01-01

217

Structural and Electrical Characterization of Pb(Sc,Ta)O 3 Thin Films Derived by Aerosol-Assisted Chemical Vapor Deposition  

Microsoft Academic Search

Lead-scandium-tantalate (Pb(Sc,Ta)O 3 ) has been deposited on Si substrate by using an aerosol-assisted chemical vapor deposition at a substrate temperature of 450°C. Crystallization behavior and electrical properties were investigated for different precursor conditions and heat-treatments in the temperature range of 650-950°C. Pb- and Ta-rich precursors yielded perovskite structure with a predominant (220) XRD peak of Pb(Sc,Ta)O 3 at an

Seon Hee Song; J.-G. Yoon; B. C. Kan; T. W. Noh

2002-01-01

218

Spatiotemporal gradients in aerosol radiative forcing and heating rate over Bay of Bengal and Arabian Sea derived on the basis of optical, physical, and chemical properties  

Microsoft Academic Search

Spatiotemporal heterogeneity in aerosol radiative forcing and heating rate have been studied over Bay of Bengal and Arabian Sea during premonsoon (March–May 2006) using aerosol optical depth (AOD), total mass, aerosol chemical composition, and radiative transfer model. Mean 0.5 ?m AOD over Bay of Bengal and Arabian Sea is 0.36 and 0.25, respectively. Water-soluble aerosols, sea salt, and mineral dust

Sumita Kedia; S. Ramachandran; Ashwini Kumar; M. M. Sarin

2010-01-01

219

Chemical synthesis of dinitrodiphenylsulfone derivatives of ethanolamine and serine and its application to the study of neighbor analysis of amino-phospholipids in the erythrocyte membrane  

Microsoft Academic Search

Summary The dinitrodiphenylsulfone derivatives of serine and ethanolamine have been prepared and their chromatographic and spectral properties are described. This cross-linking agent was used to determine the neighbor analysis of amino-phospholipids in the erythrocyte membrane. The results with erythrocyte ghosts show that at 50 µm probe 31–50% of the total phosphatidylethanolamine is cross-linked to itself and 10–12% of the phosphatidylethanolamine

G. V. Marinetti; R. Love

1976-01-01

220

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.

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

2013-01-01

221

Crystal Structure of Chemically Synthesized [N33A] Stromal Cell-Derived Factor 1alpha , a Potent Ligand for the HIV1 ``Fusin  

Microsoft Academic Search

Stromal cell-derived factor-1alpha (SDF-1alpha ) is a member of the chemokine superfamily and functions as a growth factor and chemoattractant through activation of CXCR4\\/LESTR\\/Fusin, a G protein-coupled receptor. This receptor also functions as a coreceptor for T-tropic syncytium-inducing strains of HIV-1. SDF-1alpha antagonizes infectivity of these strains by competing with gp120 for binding to the receptor. The crystal structure of

Chris Dealwis; Elias J. Fernandez; Darren A. Thompson; Reyna J. Simon; Michael A. Siani; Elias Lolis

1998-01-01

222

Synthesis, structures, properties, and chemical-sensor application of iridium(III) bis-cyclometallated complexes with two pyridine-derived ligands  

NASA Astrophysics Data System (ADS)

Treatment of cis-[Ir(? 2-ppy) 2(MeCN) 2]NO 3 ( 1, ppy = 2-phenylpyridine) with isonicotinaldehyde, ethyl isonicotinate, and 4-aminopyridine afforded cis-[Ir(? 2-ppy) 2L 2]NO 3 (L = 4-pyCHO ( 2), 4-pyCOOEt ( 3), 4-pyNH 2 ( 4)). The photophysical properties of these complexes were determined. Complex 4 is a good light-emitting chemical sensor toward silver trifluoromethanesulfonate in methanol. Crystal structures of 2 and 3 as well as that of the adduct, formed between 4 and AgNO 3, have been characterized by X-ray diffraction.

Sie, Wu-Sian; Lee, Gene-Hsiang; Tsai, Kevin Yun-Da; Chang, I.-Jy; Shiu, Kom-Bei

2008-11-01

223

Synthesis, structures, properties, and chemical-sensor application of iridium(III) bis-cyclometallated complexes with two pyridine-derived ligands  

Microsoft Academic Search

Treatment of cis-[Ir(?2-ppy)2(MeCN)2]NO3 (1, ppy=2-phenylpyridine) with isonicotinaldehyde, ethyl isonicotinate, and 4-aminopyridine afforded cis-[Ir(?2-ppy)2L2]NO3 (L=4-pyCHO (2), 4-pyCOOEt (3), 4-pyNH2 (4)). The photophysical properties of these complexes were determined. Complex 4 is a good light-emitting chemical sensor toward silver trifluoromethanesulfonate in methanol. Crystal structures of 2 and 3 as well as that of the adduct, formed between 4 and AgNO3, have been

Wu-Sian Sie; Gene-Hsiang Lee; Kevin Yun-Da Tsai; I-Jy Chang; Kom-Bei Shiu

2008-01-01

224

Derivation of a chemical-specific adjustment factor (CSAF) for use in the assessment of risk from chronic exposure to ethylene glycol: Application of international programme for chemical safety guidelines  

SciTech Connect

The International Programme for Chemical Safety (IPCS) has developed a set of guidelines ('the Guidance') for the establishment of Chemical-Specific Adjustment Factors (CSAFs) for in the assessment of toxicity risk to the human population as a result of chemical exposure. The development of case studies is encouraged in the Guidance document and comments on them have been encouraged by the IPCS. One provision in the Guidance is for the determination of CSAFs based on human data. We present a case study of the use of the Guidance for the determination of the CSAF for ethylene glycol (EG) primarily utilizing clinically obtained data. The most relevant endpoint for this analysis was deemed to be acute renal injury. These data were applied based on an assessment of the known pharmaco/toxico-kinetic properties of EG. Because of the lack of both bioaccumulation of EG and reports of chronic or progressive renal injury from EG, it was concluded that the most appropriate model of chronic exposure is one of repeated acute episodes. The most relevant exposure metric was determined to be plasma glycolate concentration. Based on a prospective human study of EG-poisoned patients, the NOAEL for glycolate was found to be 10.1 mM. This value is similar to that obtained from animal data. The application of the Guidelines to this data resulted in a CSAF of 10.24, corresponding to a daily EG dose of 43.7 mg/kg/day. In 2000, Health Canada (HC) produced an animal data-based analysis of the maximum tolerated dose of EG. The results of our analysis are compared with those of HC, and the strengths and weaknesses of these two data types related to EG are discussed.

Palmer, Robert B. [University of Colorado Health Sciences Center, Denver, CO 80262 (United States)]. E-mail: RPalmer@Toxicologyassoc.com; Brent, Jeffrey [University of Colorado Health Sciences Center, Denver, CO 80262 (United States)

2005-09-01

225

Chemical modification of ascorbic acid and evaluation of its lipophilic derivatives as inhibitors of secretory phospholipase A 2 with anti-inflammatory activity  

Microsoft Academic Search

The halo 6-fatty acid esters of l-ascorbic acid 3a, 3b and 6-fatty acid esters of l-ascorbic acid 5a–g were achieved from l-ascorbic acid 1. Compounds 3a, 3b and 5a–g were evaluated for anti-oxidant, anti-lipid peroxidation, and secretory phospholipase A2 (sPLA2) inhibition in vitro, and sPLA2 induced mouse paw edema. All the derivatives retained their anti-oxidant property compared to ascorbic acid

Riyaz Mohamed; K. K. Dharmappa; Shaista Tarannum; N. M. Jameel; S. A. Kannum; H. S. Ashrafulla; Lokanath Rai; Cletus JMD’ Souza; M. A. Shekhar; Bannikuppe S. Vishwanath

2010-01-01

226

From scratch to value: engineering Escherichia coli wild type cells to the production of L-phenylalanine and other fine chemicals derived from chorismate.  

PubMed

Recombinant strains of Escherichia coli K-12 for the production of the three aromatic amino acids (L-phenylalanine, L-tryptophan, L-tyrosine) have been constructed. The largest demand is for L-phenylalanine (L-Phe), as it can be used as a building block for the low-calorie sweetener, aspartame. Besides L-Phe, an increasing number of shikimic acid pathway intermediates can be produced from appropriate E. coli mutants with blocks in this pathway. The last common intermediate, chorismate, in E. coli not only serves for production of aromatic amino acids but can also be used for high-titer production of non-aromatic compounds, e.g., cyclohexadiene-transdiols. In an approach to diversity-oriented metabolic engineering (metabolic grafting), platform strains with increased flux through the general aromatic pathway were created by suitable gene deletions, additions, or rearrangements. Examples for rational strain constructions for L-phenylalanine and chorismate derivatives are given with emphasis on genetic engineering. As a result, L-phenylalanine producers are available, which were derived through several defined steps from E. coli K-12 wild type. These mutant strains showed L-phenylalanine titers of up to 38 g/l of L-phenylalanine (and up to 45.5 g/l using in situ product recovery). Likewise, two cyclohexadiene-transdiols could be recovered. PMID:17435995

Sprenger, Georg A

2007-06-01

227

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

PubMed Central

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

Bodoprost, Juliana; Rosemeyer, Helmut

2007-01-01

228

Identification of a Chemical Probe for Bromo and Extra C-Terminal Bromodomain Inhibition through Optimization of a Fragment-Derived Hit  

PubMed Central

The posttranslational modification of chromatin through acetylation at selected histone lysine residues is governed by histone acetyltransferases (HATs) and histone deacetylases (HDACs). The significance of this subset of the epigenetic code is interrogated and interpreted by an acetyllysine-specific protein–protein interaction with bromodomain reader modules. Selective inhibition of the bromo and extra C-terminal domain (BET) family of bromodomains with a small molecule is feasible, and this may represent an opportunity for disease intervention through the recently disclosed antiproliferative and anti-inflammatory properties of such inhibitors. Herein, we describe the discovery and structure–activity relationship (SAR) of a novel, small-molecule chemical probe for BET family inhibition that was identified through the application of structure-based fragment assessment and optimization techniques. This has yielded a potent, selective compound with cell-based activity (PFI-1) that may further add to the understanding of BET family function within the bromodomains.

2012-01-01

229

Bone Marrow-derived Mesenchymal Stem Cells Affect Immunologic Profiling of Interleukin-17-secreting Cells in a Chemical Burn Mouse Model  

PubMed Central

Purpose This study investigated interleukin (IL)-17-secreting cell involvement in sterile inflammation, and evaluated the effect of mesenchymal stem cells (MSCs) on IL-17-secreting cell immunologic profiling. Methods Twenty mice were sacrificed at time points of 6 hours, 1 day, 1 week, and 3 weeks (each group, n = 5) after the cornea was chemically injured with 0.5N NaOH; IL-17 changes in the cornea were evaluated using enzyme-linked immunosorbent assay. Further, IL-17 secreting cells were assessed in the cervical lymph nodes by a flow cytometer. Rat MSCs were applied intraperitoneally in a burn model (n = 10), IL-17-secreting T helper 17 (Th17) cell and non-Th17 cell changes were checked using a flow cytometer in both cornea and cervical lymph nodes at 1week, and compared with those in the positive control (n = 10). Results IL-17 was highest in the cornea at 1 week, while, in the cervical lymph nodes, IL-17-secreting cells showed early increase at 6 hours, and maintained the increase through 1 day to 1 week, and levels returned to the basal level at 3 weeks. Specifically, the non-Th17 cells secreted IL-17 earlier than the Th17 cells. When the MSCs were applied, IL-17 secretion was reduced in CD3(+)CD4(-)CD8(-), CD3(+)CD4(+)CD8(-), and CD3(+) CD4(-)CD8(+) cells of the cervical lymph nodes by 53.7%, 43.8%, and 50.8%, respectively. However, in the cornea, IL-17 secretion of CD3(+)CD4(-)CD8(-) cells was completely blocked. Conclusions The results indicated that both IL-17-secreting non-Th17 and Th17 cells were involved in the chemical burn model, and MSCs appeared to mainly modulate non-Th17 cells and also partially suppress the Th17 cells.

Lee, Ja Young; Jeong, Hyun Jeong; Wee, Won Ryang

2014-01-01

230

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

231

Chemical and biological characterization of cinnamic acid derivatives from cell cultures of lavender (Lavandula officinalis) induced by stress and jasmonic acid.  

PubMed

Cell cultures of lavender (Lavandula officinalis) were analyzed for the metabolite profile under normal growth conditions and under stress as well as after jasmonic acid treatment. The main compound synthesized was rosmarinic acid, which was also secreted into the culture medium. Different solvent extraction methods at different pH values altered the profile slightly. Anoxic stress induced the synthesis of a cinnamic acid derivative, which was identified as caffeic acid by gas chromatography-mass spectrometry. Caffeic acid was also induced after treatment of the cell cultures with jasmonic acid. Although the antioxidative activity of both compounds, rosmarinic acid and caffeic acid, was confirmed in an assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH), it was demonstrated that both substances have a low cytotoxic potential in vitro using acute myeloid leukemia (HL-60) cells. The potential of the system for finding new bioactive compounds is discussed. PMID:15137835

Nitzsche, Astrid; Tokalov, Sergey V; Gutzeit, Herwig O; Ludwig-Müller, Jutta

2004-05-19

232

Quantum-chemical calculations of the tautomeric forms of azo derivatives of acetylacetone and determination of the stability constants of their complexes with rare-earth metals  

Microsoft Academic Search

The effective atomic charges in the tautomeric forms (enol-azo, keto-azo, and hydrazo) of 3-(2-hydroxy-5-nitro-3-sulfophenylazo)pentane-2,4-dione\\u000a (L1), 3-(2-hydroxy-3,5-disulfophenylazo)pentane-2,4-dione (L2), 3-(5-chloro-2-hydroxy-3-sulfophenylazo)pentane-2,4-dione (L3), 3-(2-hydroxy-4-nitrophenylazo)pentane-2,4-dione (L4), and 3-(2-hydroxyphenylazo)pentane-2,4-dione (L5) were calculated by the Hückel method (MO LCAO). It was found that the hydrazo form is most reactive for meta- and meta’-substituted derivatives (L1–3) and the keto-azo form is most reactive for para-substituted (L4) and unsubstituted

R. A. Alieva; F. G. Pashaev; A. G. Gasanov; K. T. Mahmudov

2009-01-01

233

A polybromodiphenyl ether from an Indonesian marine sponge Lamellodysidea herbacea and its chemical derivatives inhibit protein tyrosine phosphatase 1B, an important target for diabetes treatment.  

PubMed

The ethanol extract of an Indonesian marine sponge Lamellodysidea herbacea inhibited the activity of protein tyrosine phosphatase 1B (PTP1B), an important target enzyme for the treatment of type II diabetes. Bioassay-guided isolation yielded a known polybromodiphenyl ether (1) as a sole bioactive component. The structure of 1 was confirmed by spectroscopic data for 1 and its methyl ether derivative (2). Compound 1 markedly inhibited the PTP1B activity (IC?? = 0.85 ?M) and showed a moderate cytotoxicity against two human cancer cell lines, HCT-15 (colon) and Jurkat (T-cell lymphoma) cells. On the other hand, compound 2 maintained potent inhibitory activity against PTP1B (IC?? = 1.7 ?M) but did not show apparent cytotoxicity at 18 ?M against these cancer cells. Four ester derivatives [acetyl (3), butyryl (4), hexanoyl (5), and benzoyl (6)] were prepared from 1 and their activities evaluated against PTP1B and two cancer cell lines to investigate the structure-activity relationships. Although compounds 3-6 exhibited potent inhibitory effects against PTP1B activity, cytotoxicity against HCT-15 and Jurkat cells was observed as a similar efficacy to that of 1. From these results, compound 2 was found to be the best inhibitor of PTP1B with no apparent cytotoxicity. Therefore, 2 may be a lead compound for making a new type of PTP1B inhibitor. Moreover, compound 2 did not inhibit the cell growth of Huh-7 cells (hepatoma). Hepatocytes are one of the locations of PTP1B, and Huh-7 cells are used to study the mechanism of action of compound 2. PMID:23274914

Yamazaki, Hiroyuki; Sumilat, Deiske A; Kanno, Syu-ichi; Ukai, Kazuyo; Rotinsulu, Henki; Wewengkang, Defny S; Ishikawa, Masaaki; Mangindaan, Remy E P; Namikoshi, Michio

2013-10-01

234

Impact of larger rare earth Pr3+ ions on the physical properties of chemically derived PrxCoFe2-xO4 nanoparticles  

NASA Astrophysics Data System (ADS)

Rare earth Pr3+ ions with its larger ionic radii substituted CoFe2O4 nanoparticles with x ranging from 0.0 to 0.1 were synthesized by sol-gel auto-combustion chemical method. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR) and vibrating sample magnetometer (VSM) were employed to characterize the physical properties of these ferrite nanoparticles. XRD pattern reveals the formation of cubic spinel ferrite with the signature of PrFeO3 phases for x ? 0.05. SEM images show that the synthesized samples are in good homogeneity with uniformly distributed grain. The results of IR spectroscopy analysis indicated that the functional groups of cobalt spinel ferrite were formed during the sol-gel process. The cations distribution between the tetrahedral (A-site) and octahedral sites (B-site) has been estimated by XRD analysis. Room temperature magnetic measurement shows saturation magnetization and coercivity increased from 54.7 to 64.2 emu/g and 644 to 1013 Oe, respectively with the increasing Pr3+ substitution.

Pachpinde, A. M.; Langade, M. M.; Lohar, K. S.; Patange, S. M.; Shirsath, Sagar E.

2014-01-01

235

An Intercomparison and Evaluation of Aircraft-Derived and Simulated CO from Seven Chemical Transport Models During the TRACE-P Experiment  

NASA Technical Reports Server (NTRS)

Four global scale and three regional scale chemical transport models are intercompared and evaluated during NASA's TRACE-P experiment. Model simulated and measured CO are statistically analyzed along aircraft flight tracks. Results for the combination of eleven flights show an overall negative bias in simulated CO. Biases are most pronounced during large CO events. Statistical agreements vary greatly among the individual flights. Those flights with the greatest range of CO values tend to be the worst simulated. However, for each given flight, the models generally provide similar relative results. The models exhibit difficulties simulating intense CO plumes. CO error is found to be greatest in the lower troposphere. Convective mass flux is shown to be very important, particularly near emissions source regions. Occasionally meteorological lift associated with excessive model-calculated mass fluxes leads to an overestimation of mid- and upper- tropospheric mixing ratios. Planetary Boundary Layer (PBL) depth is found to play an important role in simulating intense CO plumes. PBL depth is shown to cap plumes, confining heavy pollution to the very lowest levels.

Kiley, C. M.; Fuelberg, Henry E.; Palmer, P. I.; Allen, D. J.; Carmichael, G. R.; Jacob, D. J.; Mari, C.; Pierce, R. B.; Pickering, K. E.; Tang, Y.

2002-01-01

236

Constraints on eruption dynamics of basaltic explosive activity derived from chemical and microtextural study: The example of the Fontana Lapilli Plinian eruption, Nicaragua  

NASA Astrophysics Data System (ADS)

The Fontana Lapilli deposit is one of very few examples of basaltic Plinian eruptions discovered so far. Juvenile clasts have uniform chemical composition and moderate ranges of density and bulk vesicularity. However, clast populations include two textural varieties which are microlite-poor and microlite-rich respectively. These two clast types have the same clast density range, making a distinction impossible on that base alone. The high bubble number density (˜ 10 7 cm - 3 ) and small bubble population of the Fontana clasts suggest that the magma underwent coupled degassing following rapid decompression and fast ascent rate, leading to non-equilibrium degassing with continuous nucleation as it is common for silicic analogues. The Fontana products have lower microlite contents (10-60 vol.%) with respect to the other documented basaltic Plinian eruptions suggesting that the brittle fragmentation, implied for the other basaltic Plinian deposits, does not apply to the Fontana products and another fragmentation mechanism led the basaltic magma to erupt in a Plinian fashion.

Costantini, L.; Houghton, B. F.; Bonadonna, C.

2010-01-01

237

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

238

HPLC analysis of tetrahydrobiopterin and its pteridine derivatives using sequential electrochemical and fluorimetric detection: application to tetrahydrobiopterin autoxidation and chemical oxidation  

PubMed Central

Tetrahydrobiopterin (BH4) is an essential cofactor of endothelial nitric oxide (NO) synthase and when depleted, endothelial dysfunction results with decreased production of NO. BH4 is also an anti-oxidant being a good “scavenger” of oxidative species. NADPH oxidase, xanthine oxidase, and mitochondrial enzymes producing reactive oxygen species (ROS) can induce elevated oxidant stress and cause BH4 oxidation and subsequent decrease in NO production and bioavailability. In order to define the process of ROS-mediated BH4 degradation, a sensitive method for monitoring pteridine redox-state changes is required. Considering that the conventional fluorescence method is an indirect method requiring conversion of all pteridines to oxidized forms, it would be beneficial to use a rapid quantitative assay for the individual detection of BH4 and its related pteridine metabolites. To study, in detail, the BH4 oxidative pathways, a rapid direct sensitive HPLC assay of BH4 and its pteridine derivatives was adapted using sequential electrochemical and fluorimetric detection. We examined BH4 autoxidation, hydrogen peroxide- and superoxide-driven oxidation, and Fenton reaction hydroxyl radical-driven BH4 transformation. We demonstrate that the formation of the primary two-electron oxidation product, dihydrobiopterin (BH2), predominates with oxygen-induced BH4 autoxidation and superoxide-catalyzed oxidation, while the irreversible metabolites, pterin and dihydroxanthopterin (XH2), are largely produced during hydroxyl radical-driven BH4 oxidation.

Biondi, Roberto; Ambrosio, Giuseppe; De Pascali, Francesco; Tritto, Isabella; Capodicasa, Enrico; Druhan, Lawrence J.; Hemann, Craig; Zweier, Jay L.

2012-01-01

239

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

240

Electron localization function study on the chemical bonding in a real space for tetrahedrane, cubane, adamantane, and dodecahedrane and their perfluorinated derivatives and radical anions.  

PubMed

The nature of chemical bonding in caged cycloalkanes CnXn, CnFn(-•), (n = 4, 8, 20; X = H, F), and C10X16, C10F16(-•), (X = H, F) has been investigated using topological analysis of the ELF function, electron density, and the Laplacian of electron density at density functional theory (DFT) level. The bonding analysis performed for the perfluorinated radical anion of dodecahedrane (C20F20(-•)), bestowing an additional electron, shows an unexpected local maximum of the ELF inside the carbon cage. The presence of such an attractor confirms the sigma stellation concept presented by Irikura (J. Phys. Chem. A 2008, 112, 983) and essential change of the electron localization inside the cage. The basin belongs to the rare asynaptic type, V(asyn), and its mean electron population is 0.26 (0.36e). The value of the integrated spin density, 0.13e, shows that both spin-up and spin-down electrons reside in the vicinity of the cage center. A similar attractor has been found for perfluorinated radical anion of adamantane (C10F16(-•)). However, the saturation of the basis set suggests that such an attractor may be an artifact. For both caged perfluorinated tetrahedrane and cubane (CnFn (-•), n = 4, 8), no valence attractors are present inside the cage. Unpaired electron density is concentrated mainly on the C-C bonding basins. The results obtained in this study are complementary to those based on the molecular orbital theory presented by Irikura. PMID:24892794

Berski, Slawomir; Gordon, Agnieszka J; Latajka, Zdzislaw

2014-06-12

241

Spatiotemporal gradients in aerosol radiative forcing and heating rate over Bay of Bengal and Arabian Sea derived on the basis of optical, physical, and chemical properties  

NASA Astrophysics Data System (ADS)

Spatiotemporal heterogeneity in aerosol radiative forcing and heating rate have been studied over Bay of Bengal and Arabian Sea during premonsoon (March-May 2006) using aerosol optical depth (AOD), total mass, aerosol chemical composition, and radiative transfer model. Mean 0.5 ?m AOD over Bay of Bengal and Arabian Sea is 0.36 and 0.25, respectively. Water-soluble aerosols, sea salt, and mineral dust constitute ˜98% of total aerosol mass while black carbon aerosols contribute ?2% over the two oceanic regions. Sensitivity tests reveal that (1) curvature effect in AOD spectra has insignificant impact in modifying the aerosol radiative forcing and heating rate and (2) the net Earth-atmosphere energy content shows minor differences when aerosol vertical profiles are used. Over Bay of Bengal the average aerosol forcing is estimated to be -12.0, -22.4, and 10.4 W m-2 at the top of the atmosphere (TOA), at the surface (SFC), and in atmosphere (ATM), respectively. The average aerosol radiative forcing is less negative over Arabian Sea and is -10.5, -15.8, and 5.3 W m-2 at TOA, SFC, and ATM, respectively. Aerosol radiative forcing decreases in magnitude from north to south over Bay of Bengal whereas an opposite trend is noteworthy over Arabian Sea. The average atmospheric heating rate over Bay of Bengal is ˜0.3 K/d, a factor of 2 higher than that over Arabian Sea. Furthermore, ATM warming and associated heating rate are the lowest compared to earlier results as scattering aerosols are dominant during premonsoon (March-May). These results have implications to the assessment of regional and seasonal climate impacts.

Kedia, Sumita; Ramachandran, S.; Kumar, Ashwini; Sarin, M. M.

2010-04-01

242

High affinity tamoxifen derivatives  

US Patent & Trademark Office Database

The synthesis of tamoxifen derivatives, most particularly halo, halo alkyl, hydroxy, and amino tamoxifen derivatives is disclosed. The native tamoxifen molecule includes a substituted chemical group positioned on the aliphatic chain of the tamoxifen molecule. Particular tamoxifen derivatives of the invention include chloro, bromo, iodo, fluoro, amino and DTPA tamoxifen derivatives, and corresponding lower alkyl halogenated forms. The halogenated tamoxifen derivatives possess superior binding affinities for estrogen receptor rich tissues, such as uterine tissue and breast tissue, relative to unsubstituted native tamoxifen. Radiolabeled forms of the tamoxifen derivatives may be used as highly specific imaging agents for estrogen receptor rich tissues. The fluoro and bromo tamoxifen derivatives are particularly useful for imaging estrogen receptors by PET whereas the iodinated tamoxifens are particularly useful in imaging estrogen receptors by SPECT. Rapid and efficient methods of preparing the tamoxifen derivatives having high specific activity (>6 Ci/.mu.mol) are also disclosed. Aliphatic chain substituted tamoxifen derivatives are shown to possess greater estrogen receptor binding affinity and more potent tumor cell inhibition than tamoxifen or tamoxifen derivatives substituted at other locations on the molecule (i.e., non-aliphatic chain substituted tamoxifen). The tanioxifen derivatives of the present invention may advantageously be used as anti-cancer therapeutic agents to halt estrogen-receptor positive tumors, such as those of breast and uterine tissue. The present invention also provides a hydrophilic DTPA-tamnoxifen analogue, and uses thereof in imaging estrogen receptor positive ER+ lesions.

2000-08-01

243

Chemical modification of ascorbic acid and evaluation of its lipophilic derivatives as inhibitors of secretory phospholipase A(2) with anti-inflammatory activity.  

PubMed

The halo 6-fatty acid esters of L-ascorbic acid 3a, 3b and 6-fatty acid esters of L-ascorbic acid 5a-g were achieved from L-ascorbic acid 1. Compounds 3a, 3b and 5a-g were evaluated for anti-oxidant, anti-lipid peroxidation, and secretory phospholipase A(2) (sPLA(2)) inhibition in vitro, and sPLA(2) induced mouse paw edema. All the derivatives retained their anti-oxidant property compared to ascorbic acid at 6 × 10(-4)M and are good inhibitors of lipid peroxidation at 1 mg ml(-1) as evaluated by 2, 2-Diphenyl-1-picrylhydrazyl radical and thio-barbituric acid methods, respectively. Compounds 5e and 5f significantly inhibited purified group I sPLA(2) from Naja naja and group II sPLA(2) from Vipera russelli, human synovial fluid and human pleural fluid with IC(50) value ranging from 64 ± 1.95 to 82 ± 1.3 and 48 ± 2.27 to 61 ± 2.23 ?M, respectively. The compounds 5e and 5f also showed varying degree of potency in neutralizing indirect hemolytic activity of sPLA(2) at 50 ?M concentration, and sPLA(2) induced mouse paw edema at the dose 3 mg/kg. Further docking studies also confirmed that compounds 5e and 5f have maximum interaction with increasing negative energy value. Single molecule possessing both anti-oxidant and anti-inflammatory activities is of great therapeutic significance in inflammatory disorders. PMID:20730622

Mohamed, Riyaz; Dharmappa, K K; Tarannum, Shaista; Jameel, N M; Kannum, S A; Ashrafulla, H S; Rai, Lokanath; Souza, Cletus Jmd'; Shekhar, M A; Vishwanath, Bannikuppe S

2010-12-01

244

40 CFR 721.10039 - Diethoxybenzenamine derivative, diazotized, coupled with aminonaphthalenesulfonic acid derivative...  

Code of Federal Regulations, 2011 CFR

...aminonaphthalenesulfonic acid derivative, ammonium salt (generic). 721.10039 Section 721...aminonaphthalenesulfonic acid derivative, ammonium salt (generic). (a) Chemical substance...aminonaphthalenesulfonic acid derivative, ammonium salt (PMN P-02-514) is subject to...

2011-07-01

245

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

PubMed

A 34-amino-acid peptide has been chemically synthesized based on a sequence from human alpha-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 cysteine residues on the peptide. Interpeptide cross-linking does not occur. The active and inactive forms of the peptide have almost identical secondary structures as shown by circular dichroism (CD). Zinc ions bind to the active peptide and completely prevents formation of the inactive form. Cobalt(II) ions also bind to the peptide, and the UV-Vis absorption spectrum of the cobalt-peptide complex shows that: (1) a near-UV sulfur-to-metal-ion charge-transfer band had a molar extinction coefficient consistent with two thiolate bonds to Co(II); (2) the lowest-energy visible d-d transition maximum at 659 nm, also, demonstrated that the two cysteine residues are ligands for the metal ion; (3) the d-d molar extinction coefficient showed that the metal ion-ligand complex was in a distorted tetrahedral symmetry. The peptide has two cysteines, and it is speculated that the other two metal ion ligands might be the two histidines. The Zn(II)- and Co(II)-peptide complexes had similar peptide conformations as indicated by their ultraviolet CD spectra, which differed very slightly from that of the free peptide. Surprisingly, the cobalt ions acted in the reverse of the zinc ions in that, instead of stabilizing anti-growth form of the peptide, they catalyzed its loss. Metal ion control of peptide function is a saliently interesting concept. Calcium ions, in the conditions studied, apparently do not bind to the peptide. Trifluoroethanol and temperature (60 degrees C) affected the secondary structure of the peptide, and the peptide was found capable of assuming various conformations in solution. This conformational flexibility may possibly be related to the biological activity of the peptide. PMID:11687299

MacColl, R; Eisele, L E; Stack, R F; Hauer, C; Vakharia, D D; Benno, A; Kelly, W C; Mizejewski, G J

2001-10-01

246

Seven New and Two Known Lipopeptides as well as Five Known Polyketides: The Activated Production of Silent Metabolites in a Marine-Derived Fungus by Chemical Mutagenesis Strategy Using Diethyl Sulphate  

PubMed Central

AD-2-1 is an antitumor fungal mutant obtained by diethyl sulfate mutagenesis of a marine-derived Penicillium purpurogenum G59. The G59 strain originally did not produce any metabolites with antitumor activities in MTT assays using K562 cells. Tracing newly produced metabolites under guidance of MTT assay and TLC analysis by direct comparison with control G59 extract, seven new (1–7) and two known (8–9) lipopeptides were isolated together with five known polyketides 10–14 from the extract of mutant AD-2-1. Structures of the seven new compounds including their absolute configurations were determined by spectroscopic and chemical evidences and named as penicimutalides A–G (1–7). Seven known compounds were identified as fellutamide B (8), fellutamide C (9), 1?-O-methylaverantin (10), averantin (11), averufin (12), nidurufin (13), and sterigmatocystin (14). In the MTT assay, 1–14 inhibited several human cancer cell lines to varying extents. All the bioassays and HPLC-photodiode array detector (PDAD)-UV and HPLC-electron spray ionization (ESI)-MS analyses demonstrated that the production of 1–14 in the mutant AD-2-1 was caused by the activated production of silent metabolites in the original G59 fungal strain. Present results provided additional examples for effectiveness of the chemical mutagenesis strategy using diethyl sulphate mutagenesis to discover new compounds by activating silent metabolites in fungal isolates.

Wu, Chang-Jing; Li, Chang-Wei; Cui, Cheng-Bin

2014-01-01

247

Seven new and two known lipopeptides as well as five known polyketides: the activated production of silent metabolites in a marine-derived fungus by chemical mutagenesis strategy using diethyl sulphate.  

PubMed

AD-2-1 is an antitumor fungal mutant obtained by diethyl sulfate mutagenesis of a marine-derived Penicillium purpurogenum G59. The G59 strain originally did not produce any metabolites with antitumor activities in MTT assays using K562 cells. Tracing newly produced metabolites under guidance of MTT assay and TLC analysis by direct comparison with control G59 extract, seven new (1-7) and two known (8-9) lipopeptides were isolated together with five known polyketides 10-14 from the extract of mutant AD-2-1. Structures of the seven new compounds including their absolute configurations were determined by spectroscopic and chemical evidences and named as penicimutalides A-G (1-7). Seven known compounds were identified as fellutamide B (8), fellutamide C (9), 1'-O-methylaverantin (10), averantin (11), averufin (12), nidurufin (13), and sterigmatocystin (14). In the MTT assay, 1-14 inhibited several human cancer cell lines to varying extents. All the bioassays and HPLC-photodiode array detector (PDAD)-UV and HPLC-electron spray ionization (ESI)-MS analyses demonstrated that the production of 1-14 in the mutant AD-2-1 was caused by the activated production of silent metabolites in the original G59 fungal strain. Present results provided additional examples for effectiveness of the chemical mutagenesis strategy using diethyl sulphate mutagenesis to discover new compounds by activating silent metabolites in fungal isolates. PMID:24686557

Wu, Chang-Jing; Li, Chang-Wei; Cui, Cheng-Bin

2014-01-01

248

Post-trapping derivatization of radical-derived EPR-silent adducts: application to free radical detection by HPLC/UV in chemical, biochemical, and biological systems and comparison with EPR spectroscopy.  

PubMed

Free radicals are conventionally detected by electron paramagnetic resonance (EPR) spectroscopy after being trapped as spin adducts. Albeit this technique has demonstrated utmost efficacy in studying free radicals, its application to biological settings is intrinsically hampered by the inevitable bioreduction of radical-derived paramagnetic adducts. Herein, we describe a reliable technique to detect and quantify free radical metabolites, wherein reduced alkyl- and phenyl-5,5-dimethyl-1-pyrroline N-oxide (DMPO) adducts are converted into ultrastable N-naphthoate esters. To mimic the ubiquitous in vivo microenvironment, bioreductants, exogenous thiols, and sodium borohydride were studied. Nitroxyl reduction was confirmed using EPR and triphenyltetrazolium chloride. The formation of the N-naphthoyloxy derivatives was established by liquid chromatography/mass spectrometry (LC/MS). The derivatives were chromatographed using a binary eluent. HPLC and internal standards were synthesized using Grignard addition. The labeled DMPO adduct is (1) fluorescent, (2) stable as opposed to nitroxyl radical adducts, (3) biologically relevant, and (4) excellently chromatographed. Applications encompassed chemical, biochemical, and biological model systems generating C-centered radicals. Different levels of phenyl radicals produced in situ from whole blood were successfully determined. The method is readily applicable to the detection of hydroxyl radical. Analogously, DMPO, the spin trap, could be detected with extreme sensitivity suitable for in vivo applications. The developed method proved to be a viable alternative to EPR, where for the first time the reductive loss of paramagnetic signals of DMPO-trapped free radicals is transformed into fluorescence emission. We believe the proposed methodology could represent a valuable tool to probe free radical metabolites in vivo using DMPO, the least toxic spin trap. PMID:22724922

Michail, Karim; Siraki, Arno G

2012-08-01

249

Chemical feedstocks from coal  

Microsoft Academic Search

In theory, coal can provide all the chemical feedstocks now derived from oil; however, coal-chemistry technology has become outdated and needs to be improved to meet today's economic and technical demands. To bridge this gap, this collection of essays (translated from German) presents the current possibilities for producing organic chemicals from coal and suggests some routes for future developmental work.

J. Falbe; E. Ahland; G. Baron

1982-01-01

250

Glycopeptide derivatives.  

PubMed

Resistance to glycopeptides in enterococci, which first emerged in the late 1980's and is now widespread mainly in the United States, is posing a serious clinical problem due to the lack of alternative and efficacious therapeutic options, particularly against infections caused by VanA strains that are highly resistant to glycopeptides and almost all other antibiotics. In addition, isolates of Staphylococcus aureus, known as GISA, that are poorly susceptible to vancomycin and teicoplanin have been identified. Thus, there is an urgent need to develop new and more potent glycopeptides that are active against these problematic organisms. The following review will focus on the development of second-generation glycopeptides, namely LY333328 (Eli Lilly) and BI 397 (Biosearch Italia, in license to Versicor for North America), which are currently undergoing clinical trials in humans for their promising activity against VanA enterococci (LY333328), staphylococci (BI 397), and penicillin-resistant pneumococci. Both compounds were identified as the result of chemical programs that were aimed at pursuing activity of vancomycin-like or teicoplanin-like natural glycopeptides against VanA enterococci and multidrug-resistant staphylococci. More recent approaches toward glycopeptides modified in their heptapeptide core are also described. These include compounds in which amino acids 1 and 3 are replaced with other amino acid moieties such as in the modification of the asparagine side chain on residue 3 as well as attempts to change the structure of the heptapeptide backbone in positions that are critical for the molecular interaction with susceptible D-Ala-D-Ala and resistant D-Ala-D-Lactate targets. Covalently linked glycopeptide dimers and vancomycin derivatives in which vancosamine is suitably replaced with other sugar moieties will also be covered. PMID:11562292

Malabarba, A; Ciabatti, R

2001-12-01

251

40 CFR 721.10328 - Salt of polyalkylenepolyamine derivative (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Salt of polyalkylenepolyamine derivative (generic...Specific Chemical Substances § 721.10328 Salt of polyalkylenepolyamine derivative (generic...chemical substance identified generically as salt of polyalkylenepolyamine...

2012-07-01

252

Radical-assisted chemical doping for chemically derived graphene  

NASA Astrophysics Data System (ADS)

Carrier doping of graphene is one of the most challenging issues that needs to be solved to enable its use in various applications. We developed a carrier doping method using radical-assisted conjugated organic molecules in the liquid phase and demonstrated all-wet fabrication process of doped graphene films without any vacuum process. Charge transfer interaction between graphene and dopant molecules was directly investigated by spectroscopic studies. The resistivity of the doped graphene films was drastically decreased by two orders of magnitude. The resistivity was improved by not only carrier doping but the improvement in adhesion of doped graphene flakes. First-principles calculation supported the model of our doping mechanism.

Ishikawa, Ryousuke; Ko, Pil Ju; Bando, Masashi; Kurokawa, Yasuyoshi; Sandhu, Adarsh; Konagai, Makoto

2013-12-01

253

Chemical and biological characterisation of sapinopyridione, a phytotoxic 3,3,6-trisubstituted-2,4-pyridione produced by Sphaeropsis sapinea, a toxigenic pathogen of native and exotic conifers, and its derivatives.  

PubMed

A phytotoxic trisubstituted 2,4-pyridione, named sapinopyridione, was isolated from the culture filtrates of Sphaeropsis sapinea, a fungal pathogen of conifers occurring world-wide. Three strains were isolated from two cypress species. Strain D-55 isolated from Cupressus sempervirens resulted high producer of sapinopyridione (12.3 mg l(-1)), whereas strain D-54 isolated from the same cypress species was low producer (1.1 mg l(-1)); strain D-50 isolated from C. macrocarpa was intermediate producer (5.4 mg l(-1)). Sapinopyridione was characterised by spectroscopic and chemical methods, as the 6-methyl-2-(2-methyl-1-oxobutyl)-1-oxa-5-azaspiro[2.5]oct-6-ene-4,8-dione. The structure was supported by the preparation of three key derivatives, whose phytotoxic and antimycotic activities were also tested on host plants and on three Seiridium species, virulent fungal agents of cypress canker disease. Some structure-activity relationships were identified for both phytoxicity and antifungal activities. These activities appear related to the presence of both pyridione and oxiran rings. Also the carbonyl group of the side chain seems to play a role into impart activity. PMID:16712886

Evidente, Antonio; Fiore, Michele; Bruno, Giovanni; Sparapano, Lorenzo; Motta, Andrea

2006-05-01

254

Analysis of stereoelectronic properties, mechanism of action and pharmacophore of synthetic indolo[2,1-b]quinazoline-6,12-dione derivatives in relation to antileishmanial activity using quantum chemical, cyclic voltammetry and 3-D-QSAR CATALYST procedures.  

PubMed

Several indolo[2,1-b]quinazoline-6,12-dione (tryptanthrin) derivatives exhibited remarkable activity at concentrations below 100 ng/mL when tested against in vitro Leishmania donovani amastigotes. The in vitro toxicity studies indicate that the compounds are fairly well tolerated in both macrophage and neuronal lines. An analysis based on qualitative and quantitative structure-activity relationship studies between in vitro antileishmanial activity and molecular electronic structure of 27 analogues of indolo[2,1-b]quinazoline-6,12-dione is presented here by using a combination of semi-empirical AM1 quantum chemical, cyclic voltammetry and a pharmacophore generation (CATALYST) methods. A modest to good correlation is observed between activity and a few calculated molecular properties such as molecular density, octanol-water partition coefficient, molecular orbital energies, and redox potentials. Electron transfer seems to be a plausible path in the mechanism of action of the compounds. A pharmacophore generated by using the 3-D QSAR of CATALYST produced a fairly accurate predictive model of antileishmanial activity of the tryptanthrins. The validity of the pharmacophore model extends to structurally different class of compounds that could open new frontiers for study. The carbonyl group of the five- and six-membered rings in the indolo[2,1-b]quinazoline-6,12-dione skeleton and the electron transfer ability to the carbonyl atom appear to be crucial for activity. PMID:11937358

Bhattacharjee, Apurba K; Skanchy, David J; Jennings, Barton; Hudson, Thomas H; Brendle, James J; Werbovetz, Karl A

2002-06-01

255

Design and Synthesis of Human ABCB1 (P-Glycoprotein) Inhibitors by Peptide Coupling of Diverse Chemical Scaffolds on Carboxyl and Amino Termini of (S)-Valine-Derived Thiazole Amino Acid.  

PubMed

P-glycoprotein (P-gp) serves as a therapeutic target for the development of multidrug resistance reversal agents. In this study, we synthesized 21 novel compounds by peptide coupling at corresponding carboxyl and amino termini of (S)-valine-based bis-thiazole and monothiazole derivatives with diverse chemical scaffolds. Using calcein-AM efflux assay, we identified compound 28 (IC50 = 1.0 ?M) carrying 3,4,5-trimethoxybenzoyl and 2-aminobenzophenone groups, respectively, at the amino and carboxyl termini of the monothiazole zwitter-ion. Compound 28 inhibited the photolabeling of P-gp with [(125)I]-iodoarylazidoprazosin with IC50 = 0.75 ?M and stimulated the basal ATP hydrolysis of P-gp in a concentration-dependent manner (EC50 ATPase = 0.027 ?M). Compound 28 at 3 ?M reduced resistance in cytotoxicity assay to paclitaxel in P-gp-expressing SW620/Ad300 and HEK/ABCB1 cell lines. Biochemical and docking studies showed site-1 to be the preferable binding site for 28 within the drug-binding pocket of human P-gp. PMID:24773054

Singh, Satyakam; Prasad, Nagarajan Rajendra; Chufan, Eduardo E; Patel, Bhargav A; Wang, Yi-Jun; Chen, Zhe-Sheng; Ambudkar, Suresh V; Talele, Tanaji T

2014-05-22

256

Discrete Derivatives  

NASA Astrophysics Data System (ADS)

The method of finite-differences is an important technique used to obtain numerical solutions to differential equations. Critical to the construction of such discrete models is how should the discrete representations of the derivatives be formulated? A prior, there exists many possibilities; examples, include the forward- and backward-Euler expressions, as well as various central-differences. However, it has become clear in recent years that the order of the discrete derivative must be the same as the particular order of the derivative appearing in the differential equation. If not, numerical instabilities will appear; these are solutions to the discrete equations that do not correspond to any solutions of the original differential equations. We show that discrete representations of first-derivatives can be constructed such that the elementary numerical instabilities do not occur. Our method generalizes the usual calculus based definition of the derivative. The general scalar ODE is used to illustrate our method.

Mickens, Ronald E.

2000-11-01

257

Induction of CYP1A1, CYP1A2, and CYP1B1 mRNAs by nitropolycyclic aromatic hydrocarbons in various human tissue-derived cells: chemical-, cytochrome P450 isoform-, and cell-specific differences.  

PubMed

Nitropolycyclic aromatic hydrocarbons (NPAHs) are found in diesel exhaust and ambient air. NPAHs as well as polycyclic aromatic hydrocarbons (PAHs) are known to have mutagenicity, carcinogenicity, and endocrine-disruptive effects. In the present study, the inducibility of the human cytochrome P450-1 (CYP1) family by NPAHs was compared with those produced by their parent PAHs and some reductive metabolites, amino-PAHs. Furthermore, to investigate the differences in the inducibility of the CYP1 family in human tissues, various human tissue-derived cell lines, namely HepG2 (hepatocellular carcinoma), ACHN (renal carcinoma), A549 (lung carcinoma), MCF-7 (breast carcinoma), LS-180 (colon carcinoma), HT-1197 (bladder carcinoma), HeLa (cervix of uterus adenocarcinoma), OMC-3 (ovarian carcinoma), and NEC14 (testis embryonal carcinoma), were treated with NPAHs, PAHs, or amino-PAHs. The mRNA levels of CYP1A1, CYP1A2, and CYP1B1 were determined with reverse transcription-polymerase chain reaction (RT-PCR). The cell lines were classified into two groups: CYP1 inducible cell lines, comprising HepG2, MCF-7, LS-180, and OMC-3 cells, and CYP1 non-inducible cell lines, comprising ACHN, A549, HT-1197, HeLa, and NEC14 cells. In inducible cell lines, the induction profile of chemical specificity was similar for CYP1A1, CYP1A2, and CYP1B1, although the extent of induction differed among the cell lines and for the CYP isoforms. Pyrene, 1-nitropyrene, 1-aminopyrene, 1,3-, 1,6-, and 1,8-dinitropyrenes slightly induced CYP1 mRNAs, but 1,3-dinitropyrene produced a 6-fold induction of CYP1A1 mRNA in MCF-7 cells. 2-Nitrofluoranthene and 3-nitrofluoranthene exhibited stronger inducibility than fluoranthene in the inducible cell lines. 6-Nitrochrysene induced CYP1 mRNAs to the same extent or more potently than chrysene. The induction potencies of 6-nitrobenzo[ a]pyrene and 7-nitrobenz[ a]anthracene were weaker than those of their parents benzo[ a]pyrene and benz[ a]anthracene, respectively. This study demonstrated that NPAHs as well as PAHs induced human CYP1A1, CYP1A2, and CYP1B1 in a chemical-, CYP isoform-, and cell-specific manner. Furthermore, the cell-specific induction of the CYP1 family was not related to the expression levels of aryl hydrocarbon receptor, aryl hydrocarbon nuclear translocator, or estrogen receptors alpha and beta. PMID:12107646

Iwanari, Masashi; Nakajima, Miki; Kizu, Ryoichi; Hayakawa, Kazuichi; Yokoi, Tsuyoshi

2002-06-01

258

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Substituted phenylimino carbamate derivative. 721.2025 Section 721...721.2025 Substituted phenylimino carbamate derivative. (a) Chemical substance...generically as a substituted phenylimino carbamate derivative (PMN P-91-487)...

2010-07-01

259

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Substituted phenylimino carbamate derivative. 721.2025 Section 721...721.2025 Substituted phenylimino carbamate derivative. (a) Chemical substance...generically as a substituted phenylimino carbamate derivative (PMN P-91-487)...

2013-07-01

260

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Substituted phenylimino carbamate derivative. 721.2025 Section 721...721.2025 Substituted phenylimino carbamate derivative. (a) Chemical substance...generically as a substituted phenylimino carbamate derivative (PMN P-91-487)...

2009-07-01

261

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

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Phosphoric acid derivative (generic name...Chemical Substances § 721.6097 Phosphoric acid derivative (generic name...substance identified generically as a phosphoric acid derivative (PMN...

2010-07-01

262

Chemical Emergencies  

MedlinePLUS

... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by military ... there are no guarantees of safety during a chemical emergency, you can take actions to protect yourself. You ...

263

Biomass, Chemicals from  

SciTech Connect

This chapter describes the use and potential use of biomass resources for chemical production as a means to displace petroleum use. Therefore, the scope of the discussion is limited to large scale, commodity chemical products that can have an impact on the energy market by displacing petroleum conversion to chemical products. This article does not address in detail specialty chemical products whose limited market would have minimal impact on energy markets; nor does it describe in detail the use of biomass for material products such as cellulosic fiber for paper or lignocellulosic material for construction materials. The use of biomass for production of a vast array of specialty chemicals based on unique biochemical structures is another part of the overall concept of a sustainable economy, but is outside the scope of this article. Chemical production from biomass is an energy issue in that biomass-derived chemicals can result in a significant impact on the petroleum requirement for petrochemicals used in modern society. Petroleum thus displaced is available for use in the energy market. Petroleum utilization for chemicals production is reported at 14% of the petroleum market in the United States. Displacement of a significant fraction of this chemical synthesis from petroleum can provide an important impact on the overall market. In 1998 the U.S. Department of Energy stated as its goal the production of at least 10% of the basic chemical building blocks from plant-derived renewables by the year 2020 (a five-fold increase) and 50% by 2050 (another five-fold increase). In the long run, utilization of renewable carbon sources for the chemical requirements of society is the only option as fossil sources become more scarce.

Elliott, Douglas C.

2004-03-15

264

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

265

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

266

Visualizing chemical reactions and crossover processes in a fuel cell inserted in the ESR resonator: detection by spin trapping of oxygen radicals, nafion-derived fragments, and hydrogen and deuterium atoms.  

PubMed

We present experiments in an in situ fuel cell (FC) inserted in the resonator of the ESR spectrometer that offered the ability to observe separately processes at anode and cathode sides and to monitor the formation of HO and HOO radicals, H and D atoms, and radical fragments derived from the Nafion membrane. The presence of the radicals was determined by spin-trapping electron spin resonance (ESR) with 5,5-dimethylpyrroline N-oxide (DMPO) as a spin trap. The in situ FC was operated at 300 K with a membrane-electrode assembly (MEA) based on Nafion 117 and Pt as catalyst, at closed and open circuit voltage conditions, CCV and OCV, respectively. Experiments with H(2) or D(2) at the anode and O(2) at the cathode were performed. The DMPO/OH adduct was detected only at the cathode for CCV operation, suggesting generation of hydroxyl radicals from H(2)O(2) formed electrochemically via the two-electron reduction of oxygen. The DMPO/OOH adduct, detected in this study for the first time in a FC, appeared at the cathode and anode for OCV operation, and at the cathode after CCV FC operation of >or=2 h. These results were interpreted in terms of electrochemical generation of HOO at the cathode (HO + H(2)O(2) --> H(2)O + HOO) and its chemical generation at the anode from hydrogen atoms and crossover oxygen (H + O(2) --> HOO). DMPO/H and DMPO/D adducts were detected at the anode and cathode sides, for CCV and OCV operation; H and D are aggressive radicals capable of abstracting fluorine from the tertiary carbon in the polymer membrane chain and of leading to chain fragmentation. Carbon-centered radical (CCR) adducts were detected at the cathode after CCV FC operation; weak CCR signals were also detected at the anode. CCRs can originate only from the Nafion membranes, and their presence indicates membrane fragmentation. Taken together, this study has demonstrated that FC operation involves processes such as gas crossover, reactions at the catalyst surface, and possible attack of the membrane by reactive H or D that do not occur in ex situ experiments in the laboratory, thus implying different mechanistic pathways in the two types of experiments. PMID:19453175

Danilczuk, Marek; Coms, Frank D; Schlick, Shulamith

2009-06-11

267

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...

268

Chemical Threats  

MedlinePLUS

Chemical agents are poisonous vapors, aerosols, liquids and solids that have toxic effects on people, animals or plants. They ... hazard to people and the environment. Some chemical agents may be odorless and tasteless. They can have ...

269

Sulphenamides and their derivatives  

NASA Astrophysics Data System (ADS)

Information has been presented systematically on the synthesis of sulphenamides and related compounds by reaction of sulphenyl chlorides and sulphur chlorides with amines and carboxylic acid amides; by reaction of chloramines with mercaptans; by transamination of N-acylsulphenamides; and by reaction of disulphides with amines. The following chemical reactions of sulphenamides have been examined: reaction with hydrogen halides; with acids and derivatives possessing coordinatively unsaturated atoms; and the addition of sulphenamides to the double bond of carbon disulphide, isocyanates, isothiocyanates and olefins. Data are given on the physical state of sulphenamides and on the region characteristic of the S-N bond vibrations. The bibliography includes 190 references.

Petrov, K. A.; Rudnev, G. V.; Sorokin, V. D.

1990-09-01

270

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

271

Chemical Biology\\/ Chemical Genetics\\/ Chemical Genomics: Importance of Chemical Library  

Microsoft Academic Search

A new field of science, chemical biology\\/ chemical genetics\\/ chemical genomics (cb\\/cg\\/cg) has emerged since the late 1990's, especially in the United States. The NIH Roadmap agenda, Molecular Libraries Screening Center Network (MLSCN), became a drive force to push cb\\/cg\\/cg forward. Cb\\/cg\\/cg studies consist of three methodologies, chemical libraries with small molecules, high-throughput screenings, and computational databases. In this review,

Fumihiko Kugawa; Masaru Watanabe; Fuyuhiko Tamanoi

2007-01-01

272

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

273

40 CFR 721.10317 - Alkyl phosphate derivative (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Alkyl phosphate derivative (generic). 721.10317...Chemical Substances § 721.10317 Alkyl phosphate derivative (generic). (a) Chemical...substance identified generically as alkyl phosphate derivative (PMN P-02-1040)...

2013-07-01

274

Chemical engineer  

NSDL National Science Digital Library

What do chemical engineers actually do? This is the introductory page for a set of materials about chemical engineering as a career. Here the job of a chemical engineer is defined and described. Chemical engineers often work with industrial manufacturing processes that involve a mix of chemistry and engineering. In the rest of the resource, students can examine a specialized job title associated with chemical engineering: process engineer. Students can view a five-minute video clip of the process engineer as he works in a fertilizer plant making ammonia and urea. Students follow the engineer around the plant as he checks pressure in chemical lines. Students get a glimpse of the inside of a furnace during the chemical-making process. Copyright 2005 Eisenhower National Clearinghouse

Project, Iowa P.

2002-01-01

275

Chemical Cartography with APOGEE  

NASA Astrophysics Data System (ADS)

The SDSS-III APOGEE experiment is obtaining high-resolution near-IR spectra to provide measurements of stellar parameters and chemical abundances for stars in many different regions of the Galaxy. I will discuss initial results on the spatial variations of abundances derived from APOGEE data to date. In particular, I focus on mean metallicities in the Milky Way disk over a large range of Galactocentric radius (3derived from these. Issues involving distance estimates and potential biases in the mean metallicities will also be discussed, as well as directions for extending this work.

Holtzman, Jon A.; Hayden, M. R.; Bovy, J.; Majewski, S.; Johnson, J.; Zasowski, G.; Girardi, L.; Allende-Prieto, C.; Garcia Perez, A.; Meszaros, S.; Nidever, D. L.; Schiavon, R. P.; Shetrone, M. D.

2014-01-01

276

Chemical Bonds  

NSDL National Science Digital Library

Electrons are key to forming the two broad categories of chemical bonds: covalent and ionic. Atoms, which have a nucleus surrounded by electrons, are represented in several different ways. In the Chemical Bonds activity, students explore the different kinds of chemical bonds that can form, ranging from non-polar covalent to ionic. In the model depicted above students adjust the electronegativity of two atoms and see the effect it has on electron distribution and bond type.

Consortium, The C.

2011-12-11

277

Chemical Composition  

NASA Astrophysics Data System (ADS)

Measurements of the chemical compositions of materials and the levels of certain substances in them are vital when assessing and improving public health, safety and the environment, are necessary to ensure trade equity, and are required when monitoring and improving industrial products and services. Chemical measurements play a crucial role in most areas of the economy, including healthcare, food and nutrition, agriculture, environmental technologies, chemicals and materials, instrumentation, electronics, forensics, energy, and transportation.

May, Willie; Cavanagh, Richard; Turk, Gregory; Winchester, Michael; Travis, John; Smith, Melody; Derose, Paul; Choquette, Steven; Kramer, Gary; Sieber, John; Greenberg, Robert; Lindstrom, Richard; Lamaze, George; Zeisler, Rolf; Schantz, Michele; Sander, Lane; Phinney, Karen; Welch, Michael; Vetter, Thomas; Pratt, Kenneth; Scott, John; Small, John; Wight, Scott; Stranick, Stephan

278

Chemical interference of pathogen-associated molecular pattern-triggered immune responses in Arabidopsis reveals a potential role for fatty-acid synthase type II complex-derived lipid signals.  

PubMed

We describe an experimental setup using submerged cultures of Arabidopsis seedlings in 96-well microtiter plates that permits chemical intervention of rapid elicitor-mediated immune responses. Screening of a chemical library comprising 120 small molecules with known biological activities revealed four compounds reducing cellulysin- or flg22-activated gene expression of the early pathogen-associated molecular patterns (PAMP)-responsive ATL2 gene. One chemical, oxytriazine, was found to induce ATL2 gene expression in the absence of PAMP. By monitoring additional flg22-triggered immediate early plant responses, we present evidence that two compounds, triclosan and fluazinam, interfere with the accumulation of reactive oxygen species and internalization of the activated plasma membrane resident FLS2 immune receptor. Using triclosan structure types and enzyme activity inhibition assays, Arabidopsis MOD1 enoyl-acyl carrier protein reductase, a subunit of the fatty-acid synthase type II (FAS II) complex, was identified as a likely cellular target of triclosan. Inhibition of all tested elicitor-triggered early immune responses by triclosan indicates a potential role for signaling lipids in flg22-triggered immunity. Chemical profiling of eca mutants, each showing deregulated ATL2 gene expression, with the identified compounds revealed mutantspecific response patterns and allowed us to deduce tentative action sites of ECA genes relative to the compound targets. PMID:17166839

Serrano, Mario; Robatzek, Silke; Torres, Martha; Kombrink, Erich; Somssich, Imre E; Robinson, Mike; Schulze-Lefert, Paul

2007-03-01

279

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

280

40 CFR 721.1240 - Benzene, (2-bromoethyl)-, ar-bromo derivatives.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Benzene, (2-bromoethyl)-, ar-bromo derivatives...Specific Chemical Substances § 721.1240 Benzene, (2-bromoethyl)-, ar-bromo derivatives...The chemical substance identified as benzene, (2-bromoethyl)-,...

2013-07-01

281

40 CFR 721.1230 - Benzene, ethenyl-, ar-bromo derivatives.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Benzene, ethenyl-, ar-bromo derivatives...Specific Chemical Substances § 721.1230 Benzene, ethenyl-, ar-bromo derivatives...The chemical substance identified as benzene, ethenyl-, ar-bromo...

2013-07-01

282

Chemical agents and chemical terrorism.  

PubMed

Chemical terrorism is a new threat to the security of mankind, which scale essentially exceeds the impact of use of the most modem firearms. At present time all over the world threats from different radical elements to use radioactive materials, potent poisonous substances and pathogenic microorganisms for terrorist purposes became more frequent. High-toxic chemical substances can fall in terrorist hands through wide range of sources. Potentially misused types of chemical compounds are discussed in this article. PMID:15141987

Patocka, J; Fusek, J

2004-03-01

283

Chemical preconcentrator  

DOEpatents

A chemical preconcentrator is disclosed with applications to chemical sensing and analysis. The preconcentrator can be formed by depositing a resistive heating element (e.g. platinum) over a membrane (e.g. silicon nitride) suspended above a substrate. A coating of a sorptive material (e.g. a microporous hydrophobic sol-gel coating or a polymer coating) is formed on the suspended membrane proximate to the heating element to selective sorb one or more chemical species of interest over a time period, thereby concentrating the chemical species in the sorptive material. Upon heating the sorptive material with the resistive heating element, the sorbed chemical species are released for detection and analysis in a relatively high concentration and over a relatively short time period. The sorptive material can be made to selectively sorb particular chemical species of interest while not substantially sorbing other chemical species not of interest. The present invention has applications for use in forming high-sensitivity, rapid-response miniaturized chemical analysis systems (e.g. a "chem lab on a chip").

Manginell, Ronald P. (Albuquerque, NM); Frye-Mason, Gregory C. (Cedar Crest, NM)

2001-01-01

284

Chemical Name  

Cancer.gov

Attachment III Chemical Quick Reference Chart for Minors Chemical Name Select Carcinogen Reproductive Toxin LD50 < 50 mg/kg (oral rat) LD50 < 200 mg/kg for 24 hours or less (dermal rabbit) LC50 < 200 ppm or 2 mg/L for one hour (inhalation rat)

285

Enhanced detectability of fluorinated derivatives of N, N-dialkylamino alcohols and precursors of nitrogen mustards by gas chromatography coupled to Fourier transform infrared spectroscopy analysis for verification of chemical weapons convention  

Microsoft Academic Search

N,N-Dialkylamino alcohols, N-methyldiethanolamine, N-ethyldiethanolamine and triethanolamine are the precursors of VX type nerve agents and three different nitrogen mustards respectively. Their detection and identification is of paramount importance for verification analysis of chemical weapons convention. GC–FTIR is used as complimentary technique to GC–MS analysis for identification of these analytes. One constraint of GC–FTIR, its low sensitivity, was overcome by converting

Prabhat Garg; Ajay Purohit; Vijay K. Tak; D. K. Dubey

2009-01-01

286

Chemical Peeling  

MedlinePLUS

... to Ask Before a Cosmetic Procedure Chemical Peeling (AAD pamphlet) The Lunchtime Peel: What It Can Do ... et al , editors. Fitzpatrick’s Dermatology in General Medicine . 7 th edition. United States of America, McGraw Hill ...

287

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

288

Chemical Peels  

MedlinePLUS

... a brow lift, eye lift or soft-tissue filler injection. Mild scarring and certain types of acne also can be treated with chemical peels. In addition, pigmentation of the skin in the form of sun spots, age spots, ...

289

Chemical Exposure  

MedlinePLUS Videos and Cool Tools

... 2014 Related MedlinePlus Pages Environmental Health Hormones Transcript Phthalates are a group of chemicals used to make ... the ban has helped lower exposure to some phthalates, while opening the door to others. Researchers looked ...

290

Heterogeneous nature of the pre-subduction mantle wedge and their transformation to pyroxene-rich lithologies by slab-derived chemical agents: Tepic-Zacoalco rift, western Trans-Mexican Volcanic Belt  

NASA Astrophysics Data System (ADS)

Alkaline basalts with geochemical features similar to those of intraplate Ocean Islands have been emplaced along the main trace of the Tepic-Zacoalco rift (TZR) in western Mexico. Comprehensive geochemical and petrologic data on volcanic rocks along the rift indicates that the pre-subduction background mantle wedge in western Mexico is as heterogeneous as that below the Pacific basin, and includes a recycled, high-? component (HIMU; ? =238U/204Pb) in their mantle source. Olivines contained within these samples have NiO and CaO contents similar to olivines from MORB, suggesting that the source of enrichment must be entirely hosted in peridotite. More evolved rocks within the TZR have a stronger subduction signatures and water contents, and display a distinctive Pb isotopic array that suggest slab additions. Olivine phenocrysts from these rocks have lower Fo but extend higher NiO and lower CaO contents than those from more mafic magmas, suggesting derivation from a secondary pyroxenite source. It thus appears that the heterogeneous nature of the pristine pre-subduction mantle wedge in western Mexico can only be sampled when extension-driven mantle upwelling induces low extents of melting of a dry peridotitic mantle that preferentially sample its most enriched and easily fusible components. Yet even a small amount of slab-derived silica promotes a secondary petrologic transformation to pyroxene-rich lithologies that upon remelting create magmas with compositions that are similar to arc volcanoes. Metasomatic silica addition is ultimately related to the convergent margin, but deep subduction of Rivera plate below the TZR preclude a direct derivation from the slab surface. The participation of hybrid subduction mélanges that detach from the downgoing slab and melt in the hot core of the mantle wedge can provide a viable alternative explanation.

Díaz Bravo, B. A.; Gomez-Tuena, A.; Ortega-Obregón, C.; Perez-Arvizu, O.

2013-12-01

291

Phase stabilities of monoclinic oxoborates LaB 3O 6 and GdB 3O 6 in C121 and I12 /a1 phase—Energetics and chemical bonds derived from first-principles calculations  

NASA Astrophysics Data System (ADS)

The computational study on the relative phase stabilities between two monoclinic polymorphs of the lanthanide-containing oxoborates LaB 3O 6 and GdB 3O 6 is presented at the first-principles density functional theory gradient-corrected B3PW level. The hypothetical monoclinic ?-BiB 3O 6-like C121 non-centrosymmetric crystal structures were assumed for LaB 3O 6 and GdB 3O 6 and the corresponding geometries were calculated and compared with their monoclinic I12 /a1 centrosymmetric structures. The enthalpy-pressure correlations were calculated and the first-principles chemical bonds based on the crystal orbital overlapping population were quantitatively analyzed for LaB 3O 6 and GdB 3O 6. The chemical bonds between the central cation (La (III)/Gd (III)) and coordinated oxygen atoms rather than the B-O bonds in the borate units are found to stabilize the I12 /a1 centrosymmetric LaB 3O 6 and GdB 3O 6 structures with respect to the C121 non-centrosymmetric counterparts.

Yang, Jun; Dolg, Michael

2007-10-01

292

Analysis of chemical warfare agents  

Microsoft Academic Search

A series of normal aliphatic thiols have been used to derivatise the chemical warfare agents Lewisites I and II (LI and LII) in hydrocarbon matrices. Varying the chain length of the thiol allowed adjustment of derivative tR by 5.9min for Lewisite I and 5.3min for Lewisite II. Linear regression analysis of the chain length of the thiol derivatives of the

Bob Muir; Ben J Slater; David B Cooper; Christopher M Timperley

2004-01-01

293

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

Code of Federal Regulations, 2013 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....

2013-07-01

294

40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...  

Code of Federal Regulations, 2010 CFR

...acid derivative, nickel complex, alkaline salt (generic). 721.10045 Section 721...acid derivative, nickel complex, alkaline salt (generic). (a) Chemical substance...derivative, nickel complex, alkaline salt (PMN P-02-737) is subject to...

2010-07-01

295

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.

Cumpstey, Ian

2013-01-01

296

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

297

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

298

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.

299

Effect of chemically defined culture medium supplemented with beta-mercaptoethanol and amino acids on implantation and development of different stage in vivo- or in vitro-derived mouse embryos.  

PubMed

In vitro culture (IVC) systems are required for many biotechnological and assisted reproductive technologies and the researchers have been modifying in vitro embryo culture conditions to reach the comparable efficiencies provided in vivo. In the present study, the effects of beta-mercaptoethanol (Beta-ME) and amino acids (AA) on the development of mouse embryos obtained in vivo or in vitro at different stages were investigated. Chemically defined potassium simplex optimized medium (KSOM) was used as basic culture medium and six experimental groups were established and by supplementation of Beta-ME and AA into KSOM media. The quality of blastocysts was evaluated by counting the cells and determining the ratio of inner cell mass (ICM) to trophoectoderm (TE) cells. In addition, embryo transfer (ET) was performed to investigate the rate of implantation and live fetuses. The results obtained in the present study demonstrated that the combined treatment of Beta-ME and AA to 1-cell stage embryos not only enhanced in vitro development to the blastocyst stage but also improved both the number of blastocysts cells and live fetuses. PMID:15278904

Bagis, H; Odaman Mercan, H

2004-09-01

300

Steaming-induced chemical transformations and holistic quality assessment of red ginseng derived from Panax ginseng by means of HPLC-ESI-MS/MS(n)-based multicomponent quantification fingerprint.  

PubMed

The purpose of this study is to evaluate the steaming-induced chemical transformation of red ginseng manufactured from fresh ginseng by means of simultaneous quantitative and qualitative analyses with a combinative high-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS/MS(n)) technique. Thirty-six ginsenosides were identified in red ginseng and white ginseng by comparing the mass spectrum and/or matching the empirical molecular formula with that of known published compounds, and 11 of them were determined to be newly generated during the red ginseng preparatory process. The mechanisms involved were further deduced to be hydrolysis, dehydration, isomerization, and decarboxylation at C-20, and hydrolysis also occurs at C-3 or C-6 of the original ginsenosides through the mimic process of steaming and heating in laboratory. The multicomponent quantification fingerprint of ginseng was also established by HPLC-UV method, and the contents of 12 ginsenosides in red and white ginsengs from different sources were determined simultaneously. The ratio of the total content of determined malonyl ginsenosides to the corresponding neutral ginsenosides (T(m-PPD)/T(PPD)) in white ginseng ranged from 0.46 to 0.62 and from 0 to 0.19 in red ginseng. The validated method is expected to provide an effective approach to standardize the processing procedures of ginseng products and regulate the usage of ginseng in Traditional Chinese Medical prescription. PMID:22839102

Xie, Yuan-yuan; Luo, Dan; Cheng, Yi-jun; Ma, Jin-fang; Wang, Yi-ming; Liang, Qiong-lin; Luo, Guo-an

2012-08-22

301

Structural, ferroelectric, dielectric, and magnetic properties of BiFeO3/Bi3.15Nd0.85Ti3O12 multilayer films derived by chemical solution deposition  

NASA Astrophysics Data System (ADS)

BiFeO3/Bi3.15Nd0.85Ti3O12 (BFO/BNdT) multilayer films have been grown on Pt-coated silicon substrate by chemical solution deposition. Using Bi3.15Nd0.85Ti3O12 as an inducing layer, ferroelectric properties of BiFeO3 were enhanced significantly. The 2Pr and coercive electric field of the Pt/BFO/BNdT/Pt capacitor were about 22.1 ?C/cm2 and 50 kV/cm, respectively. The dielectric constant and the dissipation factor of the multilayer were 373 and 0.05 measured at 105 Hz, respectively. The multilayer capacitors not only exhibited excellent fatigue resistance without polarization reduction after 1010 switching cycles but also showed lower leakage current density (around the order of 10-9-10-7 A/cm2) and negligible data loss due to imprint. The magnetic hysteresis indicated that the multiplayer was antiferromagnetic and the saturated magnetization was about 2.47 emu/cm3.

Xie, Dan; Zang, Yongyuan; Luo, Yafeng; Han, Xueguang; Ren, Tianling; Liu, Litian

2009-04-01

302

Synthesis, vapor growth, polymerization, and characterization of thin films of novel diacetylene derivatives of pyrrole. The use of computer modeling to predict chemical and optical properties of these diacetylenes and poly(diacetylenes)  

NASA Technical Reports Server (NTRS)

In the present work two diacetylene derivatives of pyrrole which are predicted by semiempirical AM1 calculations to have very different properties, are synthesized; the polymerizability of these diacetylenes in the solid state is determined, and the results are compared to the computer predictions. Diacetylene 1 is novel in that the monomer is a liquid at room temperature; this may allow for the possibility of polymerization in the liquid state as well as the solid state. Thin poly(diacetylene) films are obtained from compound 1 by growing films of the monomer using vapor deposition and polymerizing with UV light; these films are then characterized. Interestingly, while the poly(diacetylene) from 1 does not possess good nonlinear optical properties, the monomer exhibits very good third-order effects (phase conjugation) in solution. Dilute acetone solutions of the monomer 1 give intensity-dependent refractive indices on the order of 10 exp -6 esu; these are 10 exp 6 times better than for CS2.

Paley, M. S.; Frazier, D. O.; Abeledeyem, H.; Mcmanus, S. P.; Zutaut, S. E.

1992-01-01

303

Thermodynamic Derivation of the Equilibrium Distribution Functions of Statistical Mechanics.  

ERIC Educational Resources Information Center

Presents a simplified derivation of the equilibrium distribution functions. The derivation proceeds from the change in the Helmholtz free energy when a particle is added to a system of fixed temperature, volume, and chemical potential. The derivations show the relationship between statistical mechanics and macroscopic thermodynamics. (Author/GA)

Stoeckly, Beth

1979-01-01

304

Chemicals which promote cell hybridization  

SciTech Connect

In order to identify new compounds with cell hybridization properties similar to poly(ethylene glycol), the standard method for PEG-induced cell hybridization has been employed as a screening procedure. Of 118 membrane-active agents studied, over 20 compounds were identified which promoted cell hybridization with nearly the same efficiency as PEG. PEG derivatives which retained cell hybridization activity included polymers with branched and charged structures as well as polymers with chemical alterations of the PEG monomer itself. PEG derivatives with hydrophobic moieties were generally inactive. Several chemically modified derivatives of poly(ethylene glycol), which are commercially important in the pharmaceutical and cosmetic industries, were found to be highly efficient cell hybridization agents. The biohazard of such compounds is discussed. A simpliified method is presented for the preparation and use of PEG in cell hybridization procedures.

Klebe, R.J.; Mancuso, M.G.

1981-07-01

305

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.

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

2013-01-01

306

Measurement and modeling of Ar/H2/CH4 arc jet discharge chemical vapor deposition reactors. I. Intercomparison of derived spatial variations of H atom, C2, and CH radical densities  

NASA Astrophysics Data System (ADS)

Comparisons are drawn between spatially resolved absorption spectroscopy data obtained for a 6.4 kW dc arc jet reactor, operating with Ar/H2/CH4 gas mixtures, used for deposition of thin, polycrystalline diamond films, and the results of a two-dimensional (r,z) computer model incorporating gas activation, expansion into the low pressure reactor, and the chemistry of the neutral and charged species. The experimental measurements, using either cavity ring-down spectroscopy or diode laser absorption spectroscopy, determined absolute number densities of H(n=2) atoms, and column densities of C2(a 3?u), C2(X 1?g+), and CH(X 2?) radicals, with vibrational and rotational quantum state resolutions, and their variation with height through the horizontally propagating arc jet plume. Spectra were also analyzed to obtain temperatures and local electron densities [from Stark broadening of H(n=2) absorption lines]. The experimental data are directly compared with the output data of the model that returns spatially inhomogeneous temperature, flow velocities, and number densities of 25 neutral and 14 charged species. Under the base operating conditions of the reactor [11.4 SLM (standard liters per minute) of Ar and 1.8 SLM of H2 entering the primary torch, with addition of 80 SCCM (SCCM denotes cubic centimeter per minute at STP) of CH4 downstream; 6.4 kW input power; reactor pressure of 50 Torr], the calculated and measured column and number densities agree to within factors of 2-3, the model reproduces the spatial dependence of column densities, and the mean temperatures of C2(a) and CH(X) radicals derived from spectra and model results are in good agreement. The model also captures the variation of these parameters with changes to operating conditions of the reactor such as flows of H2 and CH4, and input power. Further details of the model and the insights it provides are the subject of the accompanying paper [Mankelevich et al., J. Appl. Phys. 102, 063310 (2007) ].

Rennick, C. J.; Ma, J.; Henney, J. J.; Wills, J. B.; Ashfold, M. N. R.; Orr-Ewing, A. J.; Mankelevich, Yu. A.

2007-09-01

307

A soluble and multichromic conducting polythiophene derivative  

Microsoft Academic Search

A new soluble polythiophene derivative was synthesized by both chemical and electrochemical oxidative polymerization of 1-4-nitrophenyl-2,5-di(2-thienyl)-1H-pyrrole (SNSNO2). Chemical method produces a polymer which is completely soluble in organic solvents. The structures of both the monomer and the soluble polymer were elucidated by 1H and 13C-NMR and FTIR. The average molecular weight has been determined by GPC to be Mn=6.3×103 for

Serhat Varis; Metin Ak; Cihangir Tanyeli; Idris Mecidoglu Akhmedov; Levent Toppare

2006-01-01

308

Chemical methods for the production of graphenes  

Microsoft Academic Search

Interest in graphene centres on its excellent mechanical, electrical, thermal and optical properties, its very high specific surface area, and our ability to influence these properties through chemical functionalization. There are a number of methods for generating graphene and chemically modified graphene from graphite and derivatives of graphite, each with different advantages and disadvantages. Here we review the use of

Sungjin Park; Rodney S. Ruoff

2009-01-01

309

Inflation Rates, Car Devaluation, and Chemical Kinetics.  

ERIC Educational Resources Information Center

Describes the inflation rate problem and offers an interesting analogy with chemical kinetics. Presents and solves the car devaluation problem as a normal chemical kinetic problem where the order of the rate law and the value of the rate constant are derived. (JRH)

Pogliani, Lionello; Berberan-Santos, Mario N.

1996-01-01

310

Can hydroxylamine be a more potent nucleophile for the reactivation of tabun-inhibited AChE than prototype oxime drugs? An answer derived from quantum chemical and steered molecular dynamics studies.  

PubMed

Organophosphorus nerve agents are highly toxic compounds which strongly inhibit acetylcholinesterase (AChE) in the blood and in the central nervous system (CNS). Tabun is one of the highly toxic organophosphorus (OP) compounds and is resistant to many oxime drugs formulated for the reactivation of AChE. The reactivation mechanism of tabun-conjugated AChE with various drugs has been examined with density functional theory and ab initio quantum chemical calculations. The presence of a lone-pair located on the amidic group resists the nucleophilic attack at the phosphorus center of the tabun-conjugated AChE. We have shown that the newly designed drug candidate N-(pyridin-2-yl)hydroxylamine, at the MP2/6-31+G*//M05-2X/6-31G* level in the aqueous phase with the polarizable continuum solvation model (PCM), is more effective in reactivating the tabun-conjugated AChE than typical oxime drugs. The rate determining activation barrier with N-(pyridin-2-yl)hydroxylamine was found to be ?1.7 kcal mol(-1), which is 7.2 kcal mol(-1) lower than the charged oxime trimedoxime (one of the most efficient reactivators in tabun poisonings). The greater nucleophilicity index (?(-)) and higher CHelpG charge of pyridinylhydroxylamine compared to TMB4 support this observation. Furthermore, we have also examined the reactivation process of tabun-inhibited AChE with some other bis-quaternary oxime drug candidates such as methoxime (MMB4) and obidoxime. The docking analysis suggests that charged bis-quaternary pyridinium oximes have greater binding affinity inside the active-site gorge of AChE compared to the neutral pyridinylhydroxylamine. The peripheral ligand attached to the neutral pyridinylhydroxylamine enhanced the binding with the aromatic residues in the active-site gorge of AChE through effective ?-? interactions. Steered molecular dynamics (SMD) simulations have also been performed with the charged oxime (TMB4) and the neutral hydroxylamine. From protein-drug interaction parameters (rupture force profiles, hydrogen bonds, hydrophobic interactions), geometry and the orientation of the drug candidates, the hydroxylamine is suggested to orchestrate the reactivation process better than TMB4. Furthermore, the calculated log?P values show the effective penetration of the neutral drug candidate through the blood-brain barrier. The toxicity measurements and the IC50 values (a measure of the intrinsic affinity toward AChE) suggest that the pyridinylhydroxylamine compound could have similar toxic behavior compared to the prototype oxime antidotes used for reactivation purposes. The newly designed pyridinylhydroxylamine drug candidate can be an effective antidote both kinetically and structurally to reactivate the tabun-inhibited enzyme. PMID:24964273

Lo, Rabindranath; Ganguly, Bishwajit

2014-07-29

311

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

312

[Coliphages inactivation using chitosan derivatives].  

PubMed

The effect of chitosan fragments with different degrees of polymerization and the chemical derivatives of chitosan differing in the number of amino groups and total molecule charge on phages T2, T4, and T7 was studied. The interaction of chitosan with bacteriophage particles inactivated them to the extent dependent on the chemical properties of chitosan and its concentration. Phage T2 was found to be most susceptible to inactivation by chitosan. The polycationic nature of chitosan plays an important role in the inactivation of phages. It is assumed that the abnormal rearrangement of the basal plate of phages, the loss of long tail fibers, and probably, modification of the receptor-recognizing phage proteins may be responsible for the inactivation of coliphages by chitosan. PMID:10776628

Kochkina, Z M; Surgucheva, N A; Chirkov, S N

2000-01-01

313

Derivative Crystal Structures  

Microsoft Academic Search

There exists a class of crystal structures which are derived from others by generalization. These are here designated derivative structures. A special case of derivative structure is the popular ``superstructure.'' The symmetry of a derivative structure is a subgroup of the symmetry of the basic structure. Here the term ``subgroup'' is used in a wider sense than common in mathematical

M. J. Buerger

1947-01-01

314

Chemical spectroscopy  

SciTech Connect

The purpose of chemical spectroscopy with neutrons is to utilize the dependence of neutron scattering cross-sections on isotope and on momentum transfer (which probes the spatial extent of the excitation) to understand fundamental and applied aspects of the dynamics of molecules and fluids. Chemical spectroscopy is divided into three energy ranges: vibrational spectroscopy, 25-500 MeV, for which much of the work is done on Be-filter analyzer instruments; low energy spectroscopy, less than 25 MeV; and high resolution spectroscopy, less than 1 MeV, which typically is performed on backscattering spectrometers. Representative examples of measurements of the Q-depenence of vibrational spectra, higher energy resolution as well as extension of the Q-range to lower values at high energy transfers, and provisions of higher sensitivities in vibrational spectroscopy are discussed. High resolution, high sensitivity, and polarization analysis studies in low energy spectroscopy are discussed. Applications of very high resolution spectroscopy are also discussed. (LEW)

Eckert, J.; Brun, T.O.; Dianoux, A.J.; Howard, J.; Rush, J.J.; White, J.W.

1984-01-01

315

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

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Salt of a fatty alkylamine derivative (generic...Specific Chemical Substances § 721.558 Salt of a fatty alkylamine derivative (generic...chemical substance identified generically as a salt of a fatty alkylamine derivative...

2012-07-01

316

Method of biobased chemical production from crude bioglycerin  

US Patent & Trademark Office Database

A method of production of value-added, biobased chemicals and derivative products from bioglycerin is described herein. The present method provides methods for desalinating, decolorizing, and concentrating bioglycerin for the production of biobased chemicals, derivative products, and/or purified bioglycerin.

2014-06-24

317

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

318

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

319

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. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23949903

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

2014-07-01

320

Preparation of Benzofuran Derivatives.  

National Technical Information Service (NTIS)

The benzofuran derivatives exhibit estrogenic properties and are useful in animal husbandry, particularly as applied to steers which are grown for meat. The benzofuran derivatives are prepared by oxidizing flavylium salts.

L. Jurd

1965-01-01

321

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

322

Synthesis of acrylates and Methacrylates from Coal-Derived Syngas.  

National Technical Information Service (NTIS)

Research Triangle Institute (RTI), Eastman Chemical Company, and Bechtel collectively are developing a novel process for the synthesis of methyl methacrylate (MMA) from coal-derived syngas, under a contract from the U.S. Department of Energy, Federal Ener...

1997-01-01

323

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 ...

324

Quantum chemical assessment of benzimidazole derivatives as corrosion inhibitors  

PubMed Central

Background The majority of well-known inhibitors are organic compounds containing multiple bonds and heteroatoms, such as O, N or S, which allow adsorption onto the metal surface. These compounds can adsorb onto the metal surface and block active surface sites, reducing the rate of corrosion. Results A comparative theoretical study of three benzimidazole isomers, benzimidazole (BI), 2-methylbenzimidazole (2-CH3-BI), and 2-mercaptobenzimidazole (2-SH-BI), as corrosion inhibitors was performed using density functional theory (DFT) with the B3LYP functional basis set. Conclusions Nitro and amino groups were selected for investigation as substituents of the three corrosion inhibitors. Nitration of the corrosion inhibitor molecules led to a decrease in inhibition efficiency, while reduction of the nitro group led to an increase in inhibition efficiency. These aminobenzimidazole isomers represent a significant improvement in the inhibition efficiency of corrosion inhibitor molecules.

2014-01-01

325

Antitumour Polysaccharide derived Chemically from Natural Glucan (Pachyman)  

Microsoft Academic Search

WE have reported1 that the polysaccharide lentinan obtained from Lentinus edodes (Berk.) Sing. (a popular edible mushroom in Japan) had a strong antitumour activity against sarcoma 180 implanted subcutaneously in mice, and that almost complete regression of the tumours had been observed after ten doses of 1 mg\\/kg. Lentinan is a beta-(1-->3)-linked linear glucan having a molecular weight of 950,000-1,050,000

Goro Chihara; Junji Hamuro; Yukiko Maeda; Yoshiko Arai; Fumiko Fukuoka

1970-01-01

326

Chemical determination of unsaturation of fats and derivatives  

Microsoft Academic Search

be obtained from a new product are worth less than the cost of evaluating the surfactants. Nevertheless extensive surfactant testing is being carried out in many of the larger mills. Some of the factors which will cause further shifts in the selection of surfactants are: the steadily decreasing price of the nonionics, the increasing proportion of fabric that receives special

Don S. Bolley; James Egee; H. Ehrhardt; Botany Mills; J. M. Jester; E. A. Leonard; Joseph Oliver

1955-01-01

327

Quantum-chemical evaluation of basicity of acridine derivatives  

SciTech Connect

It has been found that the antibacterial effect of aminoacridines increases with the increase of the degree of their cationic ionization, while changes in the structure are relatively minor as concern the activity. The authors study the possible determination of a dependence between the pK of monosubstituted acridines on the position of substituent in their molecules. The theory of perturbations of molecular orbitals in its simplest variation was used. A comparison is shown of theoretical and experimental data on pK of monoaminoacridines.

Pedash, V.F.; Gaidukevich, A.N.

1986-08-01

328

A new lysine derivative and new 3-bromopyrrole carboxylic acid derivative from two marine sponges.  

PubMed

A novel lysine derivative, 1, has been isolated from the marine sponge Axinyssa terpnis, in addition to 4alpha-isocyanogorgon-11-ene and related compounds (2-4). From the marine sponge Axinella carteri, the new 3-bromopyrrole carboxylic acid derivative, 5, was obtained along with the known compounds aldisin (6) and 2-bromoaldisin (7). Both sponges were collected from Chuuk Atoll, Federated States of Micronesia. The compounds were characterized by spectroscopic and chemical methods. PMID:9548881

Li, C J; Schmitz, F J; Kelly-Borges, M

1998-03-01

329

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.

ten Dam, Jeroen; Hanefeld, Ulf

2011-01-01

330

Biologically Active Polymers: Modification and Antimicrobial Activity of Chitosan Derivatives  

Microsoft Academic Search

The principal derivative of chitin is chitosan, which is obtained by deacetylation of chitin. Chemical modification of synthetic and natural polymers is a convenient way to obtain materials with unique chemical and physical properties. Chitosan has an amino group at C-2 which is important because amino groups are nucleophilic and readily react with electrophilic reagents. Chitosan modified under mild conditions

El-Refaie Kenawy; F. Imam Abdel-Hay; Ahmed Abou El-Magd; Yehia Mahmoud

2005-01-01

331

Environmental Fate and Effects of Shale-Derived Jet Fuel.  

National Technical Information Service (NTIS)

Tests were conducted to compare the environmental fate of shale oil-derived jet fuel with that of petroleum-derived jet fuel. These tests included chemical characterization of the fuels, and the water-soluble fraction of each fuel, also measurement of vol...

P. H. Pritchard, T. P. Maziarz, L. H. Mueller, A. W. Bourquin

1988-01-01

332

Stream Health Rankings Predicted by Satellite Derived Land Cover Metrics  

Microsoft Academic Search

Land cover and land use change have long been known to influence the chemical, physical, and biological characteristics of streams. This study makes use of land cover maps derived from fine resolution satellite imagery and an extensive stream quality dataset to determine the relationship between small watershed health rankings and land cover composition and configuration. Landscape metrics were derived from

Marcia N. Snyder; Scott J. Goetz; Robb K. Wright

2005-01-01

333

Isocyanide insertion: de novo synthesis of trifluoromethylated phenanthridine derivatives.  

PubMed

A mechanistically new strategy has been described for the simple, practical, and environmentally friendly preparation of 6-(trifluoromethyl)phenanthridine derivatives using ionic isocyanide insertion from biphenyl isocyanide derivatives and Umemoto's reagent. These reactions were promoted only by inorganic base in good-to-excellent chemical yields without any external stoichiometric oxidants and radical initiators. PMID:24180686

Cheng, Yuanzheng; Jiang, Heng; Zhang, Yan; Yu, Shouyun

2013-11-01

334

21 CFR 189.120 - Cobaltous salts and its derivatives.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Cobaltous salts and its derivatives. 189.120 Section...Use as Human Food § 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4 H6 O4 ,...

2011-04-01

335

21 CFR 189.120 - Cobaltous salts and its derivatives.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Cobaltous salts and its derivatives. 189.120 Section...Use as Human Food § 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4 H6 O4 ,...

2012-04-01

336

21 CFR 189.120 - Cobaltous salts and its derivatives.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2009-04-01 true Cobaltous salts and its derivatives. 189.120 Section...Use as Human Food § 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4 H6 O4 ,...

2010-01-01

337

Chemical Ecology: Chemical Communication in Nature.  

ERIC Educational Resources Information Center

Substances that deliver chemical messages between same/different species are called semiochemicals. Surveyed are three types of semiochemicals (pheromones, allomones, and kairomones), types of organisms involved, and specific chemicals used to carry the various kinds of messages. (JN)

Wood, William F.

1983-01-01

338

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

339

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

340

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

341

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

342

Chemical oscillator as a generalized Rayleigh oscillator  

NASA Astrophysics Data System (ADS)

We derive the conditions under which a set of arbitrary two dimensional autonomous kinetic equations can be reduced to the form of a generalized Rayleigh oscillator which admits of limit cycle solution. This is based on a linear transformation of field variables which can be found by inspection of the kinetic equations. We illustrate the scheme with the help of several chemical and bio-chemical oscillator models to show how they can be cast as a generalized Rayleigh oscillator.

Ghosh, Shyamolina; Ray, Deb Shankar

2013-10-01

343

Subgiants as probes of galactic chemical evolution  

Microsoft Academic Search

Chemical abundances for 23 candidate subgiant stars have been derived with the aim at exploring their usefulness for studies of galactic chemical evolution. High-resolution spectra from ESO CAT-CES and NOT-SOFIN covered 16 different spectral regions in the visible part of the spectrum. Some 200 different atomic and molecular spectral lines have been used for abundance analysis of ˜30 elemental species.

P. Thorén; Bengt Edvardsson; Bengt Gustafsson

2004-01-01

344

Chemical Safety Audits.  

National Technical Information Service (NTIS)

The course, which is presented in cooperation with the U.S. Environmental Protection Agency's (EPA) Office of Chemical Emergency Preparedness Planning, introduces safety auditing for highly hazardous chemicals. The course covers basic chemical systems and...

1994-01-01

345

A rare glutamine derivative from the flower buds of daylily.  

PubMed

A rare glutamine derivative, hemerocallisamine I (1), was isolated from the methanolic extract of the flower buds of daylily, together with a new pyrrole alkaloid hemerocallisamine II (2) and a new ?-lactam derivative, hemerocallisamine III (3). The chemical structures of the new compounds were elucidated on the basis of chemical and physicochemical evidence. For hemerocallisamine I (1), the absolute configuration was determined by Mo-K? X-ray crystallographic analysis. This is the first report of a glutamine derivative with a pyrrole ring from natural plants. PMID:24835438

Matsumoto, Takahiro; Nakamura, Seikou; Ohta, Tomoe; Fujimoto, Katsuyoshi; Yoshikawa, Masayuki; Ogawa, Keiko; Matsuda, Hisashi

2014-06-01

346

Terpenes from Marine-Derived Fungi  

PubMed Central

Terpenes from marine-derived fungi show a pronounced degree of structural diversity, and due to their interesting biological and pharmacological properties many of them have aroused interest from synthetic chemists and the pharmaceutical industry alike. The aim of this paper is to give an overview of the structural diversity of terpenes from marine-derived fungi, highlighting individual examples of chemical structures and placing them in a context of other terpenes of fungal origin. Wherever possible, information regarding the biological activity is presented.

Ebel, Rainer

2010-01-01

347

Water-soluble derivatives of 1 -tetrahydrocannabinol.  

PubMed

Delta1-Tetrahydrocannabinol, which is resinous and insoluble in water and therefore difficult to study pharmacologically, can be converted to a watersoluble derivative without loss of its biological activity. This has been achieved by preparing esters bearing a nitrogen moiety with the use of carbodiimide as the condensing agent. The availability of such water-soluble derivatives will allow the evaluation of Delta1-tetrahydrocannabinol in self-administration studies in monkeys for its addiction liability potential in man. This technique of water solubilization is also applicable to other compounds of chemical and biological significance. PMID:5043146

Zitko, B A; Howes, J F; Razdan, R K; Dalzell, B C; Dalzell, H C; Sheehan, J C; Pars, H G; Dewey, W L; Harris, L S

1972-08-01

348

Chemical Growth Regulators for Guayule Plants  

NASA Technical Reports Server (NTRS)

Test Tubes containing Guayule - tissue cultures were used in experiments to test effects of chemical-growth regulators. The shoots grew in response to addition of 2-(3,4-dichlorophenoxy)-triethylamine (triethylamine (TEA) derivative) to agar medium. Preliminary results indicate that a class of compounds that promotes growth in soil may also promote growth in a culture medium. Further experiments are needed to define the effect of the TEA derivative.

Dastoor, M. N.; Schubert, W. W.; Petersen, G. R.

1982-01-01

349

Nature's chemicals and synthetic chemicals: comparative toxicology.  

PubMed Central

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% 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

1990-01-01

350

Acetylenic derivatives of heterocycles  

Microsoft Academic Search

1.The reaction for the catalytic replacement of halogen in the aromatic ring by the acetylenic moiety was extended to imidazole derivatives.2.In this reaction iodine in the 2 position of the imidazole ring is substantially more active than iodine in the 4 position.3.The mono- and diacetylenic derivatives of imidazole with a free acetylenic hydrogen were obtained.

M. S. Shvartsberg; L. N. Bizhan; I. L. Kotlyarevskii

1971-01-01

351

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

352

INCORPORATING BIOLOGICALLY BASED MODELS INTO ASSESSMENTS OF RISK FROM CHEMICAL CONTAMINANTS  

EPA Science Inventory

The general approach to assessment of risk from chemical contaminants in drinking water involves three steps: hazard identification, exposure assessment, and dose-response assessment. raditionally, the risks to humans associated with different levels of a chemical have been deriv...

353

[A novel naphthalene derivative from Aloe barbadensis].  

PubMed

To investigate the chemical constituents of A. barbadensis, aqueous extract of the plant was subjected to preparative medium pressure liquid chromatography (MPLC). The chemical structures were mainly determined by spectroscopic evidences (UV, IR, HR-MS, 1H NMR, 13C NMR, HSQC, 1H-1H COSY and HMBC) and chemical methods. A new O, O, O-triglucosylated naphthalene derivative, together with two known 6-phenyl-2-pyrone derivatives and four 5-methylchromones, were isolated and identified as 1-((3-((4- O-beta-D-glucopyranosyl)-beta-D-xylopyranosyloxymethyl)-1-hydroxy-8-alpha-L-rhamnopyranosyloxy)naphthalene-2-y])-ethanone (1), 10-O-beta-D-glucopyranosyl aloenin (2), aloenin B (3), aloesin (4), 8-C-glucosyl-(R)-aloesol (5), 8-C-glucosyl-7-O-methyl-(S)-aloesol (6), and isoaloeresin D (7). Compound 1 is a novel naphthalene derivative and named as aloveroside B, compounds 2-3 are isolated from this Aloe species for the first time. PMID:23888696

Wu, Xiao-Fang; Wan, Jin-Zhi; Luo, Bing-Jun; Yang, Miao-Rong; Ding, Wen-Jing; Zhong, Jia-Sheng

2013-05-01

354

Chemical Emergencies Overview  

MedlinePLUS

... that cause nausea and vomiting Hazardous chemicals by name (A-Z list) If you know the name of a chemical but aren’t sure what ... in, you can look for the chemical by name on the A–Z List of Chemical Agents . ...

355

Chemical derivation to enhance the chemical\\/oxidative stability of resorcinol-formaldehyde (RF) resin  

Microsoft Academic Search

Tank wastes at Hanford and SRS contain highly alkaline supernate solutions of conc. Na, K nitrates with large amounts of ¹³⁷Cs. It is desirable to remove and concentrate the highly radioactive fraction for vitrification. One candidate ion exchange material for removing the radiocesium is R-F resin. This report summarizes studies into synthesis and characterization of 4-derivatized R-F resins prepared in

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

1996-01-01

356

CHEMICAL SYNTHESIS OF GLYCOSYLPHOSPHATIDYLINOSITOL ANCHORS  

PubMed Central

Many eukaryotic cell-surface proteins and glycoproteins are anchored to the plasma membrane by glycosylphosphatidylinositols (GPIs), a family of glycolipids that are post-translationally attached to proteins at their C-termini. GPIs and GPI-anchored proteins play important roles in many biological and pathological events, such as cell recognition and adhesion, signal transduction, host defense, and acting as receptors for viruses and toxins. Chemical synthesis of structurally defined GPI anchors and GPI derivatives is a necessary step toward understanding the properties and functions of these molecules in biological systems and exploring their potential therapeutic applications. In the first part of this comprehensive article on the chemical synthesis of GPIs, classic syntheses of naturally occurring GPI anchors from protozoan parasites, yeast, and mammals are covered. The second part of the article focuses on recent diversity-oriented strategies for the synthesis of GPI anchors containing unsaturated lipids, “click chemistry” tags, and highly branched and modified structures.

Swarts, Benjamin M.; Guo, Zhongwu

2013-01-01

357

Teaching Cournot without Derivatives.  

ERIC Educational Resources Information Center

Presents a simple technique for teaching the Cournot model to first-year microeconomic students. Involves demonstrating, without the use of derivatives, that out of all rectangles with a common perimeter, the square has the greatest area. (RLH)

Dufwenberg, Martin

2001-01-01

358

Preparation of Benzofuran Derivatives.  

National Technical Information Service (NTIS)

The benzofuran derivatives exhibit estrogenic properties and may be used in animal husbandry. Coumestrol is synthesized by reacting 2-(2,4-dihydroxyphenyl)-3-carboalkoxy-6-hydroxy benzofuran with a strong acid in the presence of water to cause hydrolysis ...

L. Jurd

1964-01-01

359

Chemical Abundances in the Galactic Center  

NASA Astrophysics Data System (ADS)

We present chemical abundances in a sample of luminous cool stars located within 50 pc of the Galactic Center. Abundances of C, N, O, Ca and Fe are derived using high-resolution infrared spectra in the H- and K-bands. We report solar iron abundance, enhanced alpha element abundances, and CN-cycle mixed material in the atmospheres of these evolved stars.

Ramírez, S. V.; Cunha, K.; Sellgren, K.; Smith, V. V.; Blum, R. D.; Terndrup, D.

2011-05-01

360

Increment of antimycobaterial activity on lichexanthone derivatives.  

PubMed

A new dihydropyranexanthone derived from the natural xanthone lichexanthone (1) was synthesised and, together with other 18 derivatives including ?-bromo and ?-aminoalkoxylxanthones (containing methyl, ethyl, propyl, tertbutylamino and piperidinyl moieties), were tested against Mycobacterium tuberculosis. Nine ?-aminoalkoxylxanthones showed good antimycobacterial activity, and their in vitro cytotoxicity was determined using VERO cells in order to calculate the selectivity index (SI). One of these nitrogenated xanthone derivatives showed very promising results, with MIC of 2.6 ?M and SI of 48. This MIC is comparable to values found in "first and second line" drugs commonly used to treat TB. In order to understand better about this compound, it was evaluated together with two other ones that showed good SI, against resistant clinical strains of M. tuberculosis to verify the existence of cross-resistance. A chemometrical approach was useful to establish a pattern of antitubercular activity among the group of ?-aminoalkoxylxanthones, according to some structural and chemical features. PMID:23106287

Micheletti, Ana Camila; Honda, Neli Kika; Pavan, Fernando R; Leite, Clarice Q F; Matos, Maria de Fatima Cepa; Perdomo, Renata Trentin; Bogo, Danielle; Alcantara, Glaucia Braz; Beatriz, Adilson

2013-11-01

361

Conversion of tomato saponins to pregnane derivatives.  

PubMed

Here reports new conversions methods of tomato saponins, esculeoside A (1) and a mixture of esculeosides B-1 (2) and B-2 (3), (the latter two were obtained from tomato cans) into pregnane derivative (5) by an alkal treatment followed by acid treatment. Compound 1 or a mixture of 2 and 3 were each refluxed with 1?N KOH to afford a characteristic pyridine steroidal glycoside (4), which was then treated with 2?N HCl-MeOH to afford a pregnane derivative, 3?-hydroxy-5?-pregn-16-en-20-one (5). The results of the above two reactions indicated that tomato saponins are chemically closely related to pregnane hormones. We assume that the assimilated tomato saponins via the small intestine are metabolized into pregnane derivatives, demonstrating various bioactivities such as anti-cancer, anti-osteoporosis, and anti-menopausal disorder activities. PMID:24789931

Nohara, Toshihiro; Manabe, Hideyuki; Fujiwara, Yukio; Ikeda, Tsuyoshi; Ono, Masateru; Murakami, Kotaro; Nakano, Daisuke; Kinjo, Junei; Kajimoto, Tetsuya

2014-01-01

362

Ionospheric chemical releases  

NASA Technical Reports Server (NTRS)

Ionospheric plasma density irregularities can be produced by chemical releases into the upper atmosphere. F-region plasma modification occurs by: (1) chemically enhancing the electron number density; (2) chemically reducing the electron population; or (3) physically convecting the plasma from one region to another. The three processes (production, loss, and transport) determine the effectiveness of ionospheric chemical releases in subtle and surprising ways. Initially, a chemical release produces a localized change in plasma density. Subsequent processes, however, can lead to enhanced transport in chemically modified regions. Ionospheric modifications by chemical releases excites artificial enhancements in airglow intensities by exothermic chemical reactions between the newly created plasma species. Numerical models were developed to describe the creation and evolution of large scale density irregularities and airglow clouds generated by artificial means. Experimental data compares favorably with theses models. It was found that chemical releases produce transient, large amplitude perturbations in electron density which can evolve into fine scale irregularities via nonlinear transport properties.

Bernhardt, Paul A.; Scales, W. A.

1990-01-01

363

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

364

Epoxide-derived organosulfates  

NASA Astrophysics Data System (ADS)

Organosulfates (OS) are a significant fraction of secondary organic aerosol (SOA) material in the atmosphere. OS are typically surface-active, and have been suggested to cause surface tension depression in aerosols. Recent field studies suggest that epoxide-derived OS are the most abundant OS type in aerosols. Time-dependent surface tension measurements and Aerosol-CIMS characterization of two epoxides and their organosulfate products are shown. ?-pinene oxide, derived from ?-pinene, shows significant surface tension depression in H2O and ammonium sulfate. Results from cis-2,3-epoxybutane-1,4-diol (BEPOX), a butadiene-derived analog to isoprene-derived epoxydiols, are also shown. In addition, using GAMMA, a photochemical box model using coupled gas- and aqueous-phase chemistry developed in the McNeill laboratory, we show the dominance of epoxide-derived OS formation over other competing OS formation mechanisms, such as radical chemistry, under both high-NOx and low-NOx scenarios.

Schwier, A. N.; Woo, J.; McNeill, V. F.

2011-12-01

365

Carbohydrates as green raw materials for the chemical industry  

Microsoft Academic Search

In view of the impending transition of chemical industry from depleting fossil raw materials to renewable feedstocks ? the end of cheap oil is predicted for 2040 at the latest ? this account gives an overview on chemically transforming low-molecular weight carbohydrates into products with versatile industrial application profiles and the potential to replace those presently derived from petrochemical sources. To

Frieder W Lichtenthaler; Siegfried Peters

2004-01-01

366

Evaluation of surface water quality impacts of hazardous chemical sites  

Microsoft Academic Search

SUMMARY Common deficiencies in the typical evaluation of the surface water quality impacts of hazardous chemical sites are discussed. Particular attention is given to deficiencies in monitoring stormwater runoff, as well as the input of contaminated groundwaters that lead to impairment of the beneficial uses of nearby surface waters due to site-derived hazardous and deleterious chemicals. An alternative approach, Evaluation

G. Fred Lee; Anne Jones-Lee

1999-01-01

367

Empirical NMR Chemical Shift Correlations for Methyl and Methylene Protons.  

ERIC Educational Resources Information Center

Presents an internally consistent set of 63 substituent constants developed for use with the Schoolery Relationship to predict the chemical shifts of methylene protons of acyclic compounds. Chemical shift data used in deriving the constants were taken mainly from primary sources of HNMR (nuclear magnetic resonance) spectra. (JN)

Friedrich, Edwin C.; Runkle, Katherine Gates

1984-01-01

368

1,3,4-oxadiazole derivatives as potential biological agents.  

PubMed

The synthesis of novel compound libraries along with screening is a rapid and effective approach for the discovery of potential chemical agents, and it becomes an important method in pharmaceutical chemistry research. 1,3,4- oxadiazole derivatives as the typical heterocyclic compounds, exhibit a broad spectrum of biological activities and vital leading compounds for the development of chemical drugs. Herein, we focus on the synthesis and screening of novel 1,3,4-oxadiazoles derivatives with antimicrobial, antitumor or antiviral activities during the past decade. In this review, we discussed the synthetic development of 1,3,4-oxadiazoles derivatives, and also the relevant bioactivity and their prospects as the potential chemical drugs. PMID:23815585

Sun, Juan; Makawana, Jigar A; Zhu, Hai-Liang

2013-10-01

369

Myeloid derived suppressor cells  

PubMed Central

The goal of achieving measurable response with cancer immunotherapy requires counteracting the immunosuppressive characteristics of tumors. One of the mechanisms that tumors utilize to escape immunosurveillance is the activation of myeloid derived suppressor cells (MDSCs). Upon activation by tumor-derived signals, MDSCs inhibit the ability of the host to mount an anti-tumor immune response via their capacity to suppress both the innate and adaptive immune systems. Despite their relatively recent discovery and characterization, anti-MDSC agents have been identified, which may improve immunotherapy efficacy.

Waldron, Todd J.; Quatromoni, Jon G.; Karakasheva, Tatiana A.; Singhal, Sunil; Rustgi, Anil K.

2013-01-01

370

Chemical methods for the synthesis and modification of neoclerodane diterpenes.  

PubMed

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

2009-09-15

371

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

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Oxo-substituted amino-al-kanoic acid derivative. 721.430... § 721.430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical...identified generically as oxo-substituted amino al-kan-oic acid derivative (PMN...

2009-07-01

372

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

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Oxo-substituted amino-al-kanoic acid derivative. 721.430... § 721.430 Oxo-substituted amino-al-kanoic acid derivative. (a) Chemical...identified generically as oxo-substituted amino al-kan-oic acid derivative (PMN...

2010-07-01

373

Evidence for the Biogenic Formation of Amphetamine Derivatives from Components of Nutmeg  

Microsoft Academic Search

Myristicin and elemicin are phenylallyl derivatives present in nutmeg. The similarity of their chemical structure to that of mescaline or certain amphetamine derivatives has led to the assumption that the psychotropic effect of nutmeg in man is due to amphetamine derivatives endogenously produced from these phenylallyl precursors by bio-transformation. In our present study we investigated the metabolism of myristicin by

U. Braun; D. A. Kalbhen

1973-01-01

374

40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.  

Code of Federal Regulations, 2012 CFR

...derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection...derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant...derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to...

2012-07-01

375

40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.  

Code of Federal Regulations, 2010 CFR

...derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection...derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant...derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to...

2010-07-01

376

Chemical Reference Literature.  

National Technical Information Service (NTIS)

An innovative and effective laboratory experiment of chemical reference literature is reported. The objectives of the experiment are to acquaint the first term student of college chemistry with the vast source of chemical literature that is available to h...

S. M. Young

1971-01-01

377

Physical vs Chemical Changes  

NSDL National Science Digital Library

The phenomena are physical changes, including the crushing of a can, melting of ice, and melting of sugar, and chemical changes, including and the rusting of iron and burning of sugar. This analysis will address the chemical change component.

378

Chemical Weapons Convention.  

National Technical Information Service (NTIS)

On April 29, 1997, the Convention on the Prohibition of the Development, Production, Stockpiling, and Use of Chemical Weapons and on Their Destruction, known as the Chemical Weapons Convention (CWC), entered into force. At that time, the United States and...

1997-01-01

379

Advanced Chemical Engineering Research.  

National Technical Information Service (NTIS)

Ten advanced chemical engineering research projects were executed at the US Army Natick RDE Center over a three month period by students of the David H. Koch School of Chemical Engineering Practice, administered by the Massachusetts Institute of Technolog...

T. A. Hatton

1994-01-01

380

Alternatives in Chemical Education  

ERIC Educational Resources Information Center

Summarizes the educational objectives and strategies of the Chemical Technician Curriculum Project (Chem TeC), which has the primary objective of preparing a set of texts specifically for training chemical technicians. (PR)

Pecsok, Robert L.

1971-01-01

381

The Chemical Equilibrium Problem.  

National Technical Information Service (NTIS)

It has long been known that the problem of determining the equilibrium composition of a solution of chemically reacting species could be formulated as a constrained minimum problem. Previous methods for solving the chemical equilibrium problem in this for...

J. H. Bigelow

1968-01-01

382

Personal Chemical Exposure informatics  

EPA Science Inventory

Chemical Exposure science is the study of human contact with chemicals (from manufacturing facilities, everyday products, waste) occurring in their environments and advances knowledge of the mechanisms and dynamics of events that cause or prevent adverse health outcomes. (adapted...

383

Chemicals from Wood Waste.  

National Technical Information Service (NTIS)

A study of the economics of producing chemicals from wood waste was carried out for the Forest Products Laboratory. Results included: (1) outlining chemical processes based on known technology for producing methanol, ethanol, formaldehyde, furfural, and p...

A. E. Hokanson V. B. Diebold D. W. Bennett R. P. Klier S. A. Stein

1975-01-01

384

Health Aspects of Chemical Safety. Legislative and Administrative Procedures for the Control of Chemicals. Interim Document 5. Legislation and Administration.  

National Technical Information Service (NTIS)

Each year from 200 to 1000 new chemicals enter the market. Their control is vital, but possible adverse effects of chemicals on human health and the environment must be weighed against the many benefits derived from their use. Many countries have control ...

A. I. Bainova M. Idman-Philp W. Huster S. Westberg A. Gilad

1982-01-01

385

Physical and Chemical Change  

NSDL National Science Digital Library

Overview of physical and chemical changes with practice activities and a quiz. Worksheet - Physical Chemical Change Worksheet After viewing the worksheet, copy and paste it into a new blank Google Document - MyDSD Google Login Title your Document "Chemical and Physical Change". Make sure to include your name and period in the body of the doc. The answers in your document should be a different color or font. Examples of Chemical Changes Changes info page More Examples After completing the rest ...

Wood, Mr.

2010-11-15

386

Computing Equilibrium Chemical Compositions  

NASA Technical Reports Server (NTRS)

Chemical Equilibrium With Transport Properties, 1993 (CET93) computer program provides data on chemical-equilibrium compositions. Aids calculation of thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93/PC is version of CET93 specifically designed to run within 640K memory limit of MS-DOS operating system. CET93/PC written in FORTRAN.

Mcbride, Bonnie J.; Gordon, Sanford

1995-01-01

387

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

388

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.

389

Emergency management of chemical weapons injuries.  

PubMed

The potential for chemical weapons to be used in terrorism is a real possibility. Classes of chemical weapons include nerve agents, vesicants (blister agents), choking agents, incapacitating agents, riot control agents, blood agents, and toxic industrial chemicals. The nerve agents work by blocking the actions of acetylcholinesterase leading to a cholinergic syndrome. Nerve agents include sarin, tabun, VX, cyclosarin, and soman. The vesicants include sulfur mustard and lewisite. The vesicants produce blisters and also damage the upper airways. Choking agents include phosgene and chlorine gas. Choking agents cause pulmonary edema. Incapacitating agents include fentanyl and its derivatives and adamsite. Riot control agents include Mace and pepper spray. Blood agents include cyanide. The mechanism of toxicity for cyanide is blocking oxidative phosphorylation. Toxic industrial chemicals include agents such as formaldehyde, hydrofluoric acid, and ammonia. PMID:22080590

Anderson, Peter D

2012-02-01

390

Adaptability in Chemical Engineering.  

National Technical Information Service (NTIS)

The adaptability issue for chemical engineering (the ability of chemical engineers to be retrained to work in other fields and for those from other fields to be retrained for work in chemical engineering) will be discussed and illustrated in terms of (1) ...

J. S. Watson

1989-01-01

391

Chemical Exposure: An Overview  

Microsoft Academic Search

Agricultural chemicals comprise thousands of formulations, including petroleum products, pesticides, growth regulators, buffers, nutrients and fertilizers, and veterinary medications. These chemicals may be used as solids in granular, powder, pellet, or block form; liquids in mists and sprays; or in gaseous forms as fumigants or fuels. Application of chemicals to crops may be by sprays of liquids from aircraft or

JAMES E. LESSENGER

392

Chemical Education in Bulgaria  

Microsoft Academic Search

The sociopolitical changes in Eastern Europe of the 1990s and the ongoing globalization of the chemical industry and chemical education prompted this analysis of the current status of chemical education in Bulgaria, which is not very different from the educational practices in the rest of Europe. The level of chemistry knowledge expected from all high-school graduates in Bulgaria is roughly

Vladimir N. Garkov

1999-01-01

393

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...

394

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

395

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

396

Establishing Chemical Technology Programs.  

ERIC Educational Resources Information Center

In light of the increasing demand for well-prepared chemical technicians, this paper provides suggestions for two-year colleges interested in initiating or upgrading a chemical technology program. Introductory comments indicate that, from the industry standpoint, chemical technicians are invaluable, but inadequate in numbers and often unprepared.…

Hajian, Harry G.

397

Drawing Updates From Derivations  

Microsoft Academic Search

We propose a method for satisfying update requests in deductive databases. The setting is a generalization of the view update problem in relational databases. Updates can be drawn from goals and input clauses in derivations that are rooted at the request. An update may be invalidated by negation or integrity constraints. Thus, it may be necessary to try other updates,

Hendrik Decker; Siemens ZFE

1990-01-01

398

Functional Derivatives of Polyisobutene  

Microsoft Academic Search

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

Yu A. Sangalov; Yu B. Yasman

1985-01-01

399

Liquid crystalline cellulose derivatives  

SciTech Connect

Following the observation that (hydroxypropyl)cellulose in water forms an ordered cholesteric liquid crystalline phase at high polymer concentrations, reports that many other cellulose derivatives in a wide variety of solvents also form liquid crystalline solutions have appeared in the scientific and patent literature. A tabulation of cellulose-based liquid crystalline systems is presented. The formation of the ordered phase is attributed to the limited flexibility of the cellulose chain. However, some cellulose derivatives form liquid crystalline phases only in specific solvents; concentrated solutions in other solvents remain isotropic. Other cellulose derivatives, such as (hydroxypropyl)cellulose, appear to form liquid crystalline solutions in any solvent that dissolves sufficiently high concentrations of the polymer. It has been suggested that the role of flexible side-chain substituents is to allow the main chains to achieve their equilibrium orientational order. The presence of many large substituents on the cellulose backbone also increases the effective chain radius and may change the chain conformation. The effect of side-chain structure on the properties of cellulose liquid crystalline phases is thus of interest. A series of esters of (hydroxypropyl)cellulose have been prepared. In addition to forming liquid crystalline solutions in organic solvents, these materials also were found to form cholesteric thermotropic phases in the absence of solvent. The thermotropic phases show spontaneous molecular orientation and cholesteric reflection. On heating, a transformation to the isotropic melt occurs. The liquid crystalline state of cellulose and its derivatives is thus widely observed. 42 references, 4 figures, 3 tables.

Gray, D.G.

1983-01-01

400

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

401

Amphetamine derivative related deaths  

Microsoft Academic Search

Amphetamine its methylendioxy (methylendioxyamphetamine methylenedioxymethylamphetamine, methylenedioxyethylamphetamine) and methoxy derivatives (p-methoxyamphetamine and p-methoxymethylamphetamine) are widely abused in Spanish society. We present here the results of a systematic study of all cases of deaths brought to the attention of the Madrid department of the Instituto Nacional de Toxicologia from 1993 to 1995 in which some of these drugs have been found in

C Lora-Tamayo; T Tena; A Rodr??guez

1997-01-01

402

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

403

[Azo derivatives of levorin].  

PubMed

Levorin, an aromatic heptaenic antibiotic and sodium nitrite in solution of acetic acid formed a diazo compound. In the diazo reaction this compound interacted with beta-napthol or H-acid. The resulting azo compounds were readily soluble in organic solvents. In water their nitrites formed true solutions. The biological activity of the azo levorins was 100-200 times lower than that of the initial levorin. The physico-chemical characteristics of the azo levorins are presented. PMID:3947046

Mitrofanov, A A; Shenin, Iu D; Mitrofanova, V G

1986-01-01

404

Chemical Reactivity Worksheet  

NSDL National Science Digital Library

The National Oceanic and Atmospheric Administration's (NOAA) Office of Response and Restoration has created the Chemical Reactivity Worksheet to help teachers, students, and the general public learn about the chemical reactivity of thousands of common hazardous chemicals. After downloading a free program, visitors will find that the datasheets contain information about the hazards of a number of chemicals, along with information on whether a chemical reacts with air, water, or other materials. Visitors can create their own custom chemical datasheets or virtually "mix" chemicals to find out what dangers might arise from accidental mixing. The site is rounded out by an excellent FAQ section, along with information about the technical specifications of the program and a development history.

2012-08-24

405

Application of quantum-chemical approximations to environmental problems: Prediction of physical and chemical properties of TNT and related species.  

PubMed

This paper presents accurate predictions of ecologically important properties of nitroaromatic compounds and their derivatives, including vapor pressure, Henry's law constants, water solubility, octanol/water partition coefficients, heats of formation and ionization potentials. The proposed technique of calculations was based on quantum-chemical methods. The relationship between the chemical structure and mentioned physico-chemical parameters of such widespread military produced contaminants as trinitrotoluene and its derivatives was considered. We revealed that the DFT level of theory combined with the COSMO-RS technique is able to predict the studied parameters with an accuracy that results in error bars of less then one logarithmic unit. PMID:17512030

Qasim, Mohammad; Kholod, Yana; Gorb, Leonid; Magers, David; Honea, Patricia; Leszczynski, Jerzy

2007-10-01

406

Satellite-Derived Management Zones  

NASA Technical Reports Server (NTRS)

The term "satellite-derived management zones" (SAMZ) denotes agricultural management zones that are subdivisions of large fields and that are derived from images of the fields acquired by instruments aboard Earth-orbiting satellites during approximately the past 15 years. "SAMZ" also denotes the methodology and the software that implements the methodology for creating such zones. The SAMZ approach is one of several products of continuing efforts to realize a concept of precision agriculture, which involves optimal variations in seeding, in application of chemicals, and in irrigation, plus decisions to farm or not to farm certain portions of fields, all in an effort to maximize profitability in view of spatial and temporal variations in the growth and health of crops, and in the chemical and physical conditions of soils. As used here, "management zone" signifies, more precisely, a subdivision of a field within which the crop-production behavior is regarded as homogeneous. From the perspective of precision agriculture, management zones are the smallest subdivisions between which the seeding, application of chemicals, and other management parameters are to be varied. In the SAMZ approach, the main sources of data are the archives of satellite imagery that have been collected over the years for diverse purposes. One of the main advantages afforded by the SAMZ approach is that the data in these archives can be reused for purposes of precision agriculture at low cost. De facto, these archives contain information on all sources of variability within a field, including weather, crop types, crop management, soil types, and water drainage patterns. The SAMZ methodology involves the establishment of a Web-based interface based on an algorithm that generates management zones automatically and quickly from archival satellite image data in response to requests from farmers. A farmer can make a request by either uploading data describing a field boundary to the Web site or else drawing the boundary on a reference image. Hence, a farmer can start to engage in precision farming shortly after gaining access to the Web site, without the need for incurring the high costs of conventional precision-agriculture data-collection practices that include collecting soil samples, mapping electrical conductivity of soil, and compiling multiyear crop-yield data. Given the boundary of a field, a SAMZ server computes the zones within the field in a three-stage process. In the first stage, a vector-valued image of the field is constructed by assembling, from the archives, the equivalent of a stack of the available images of the field (see figure). In the second stage, the vector-valued image is analyzed by use of a wavelet transform that detects spatial variations considered significant for precision farming while suppressing small-scale heterogeneities that are regarded as insignificant. In the third stage, a segmentation algorithm assembles the zones from smaller regions that have been identified in the wavelet analysis.

Lepoutre, Damien; Layrol, Laurent

2005-01-01

407

Chemical Kinetic Modeling of Advanced Transportation Fuels  

SciTech Connect

Development of detailed chemical kinetic models for advanced petroleum-based and nonpetroleum based fuels is a difficult challenge because of the hundreds to thousands of different components in these fuels and because some of these fuels contain components that have not been considered in the past. It is important to develop detailed chemical kinetic models for these fuels since the models can be put into engine simulation codes used for optimizing engine design for maximum efficiency and minimal pollutant emissions. For example, these chemistry-enabled engine codes can be used to optimize combustion chamber shape and fuel injection timing. They also allow insight into how the composition of advanced petroleum-based and non-petroleum based fuels affect engine performance characteristics. Additionally, chemical kinetic models can be used separately to interpret important in-cylinder experimental data and gain insight into advanced engine combustion processes such as HCCI and lean burn engines. The objectives are: (1) Develop detailed chemical kinetic reaction models for components of advanced petroleum-based and non-petroleum based fuels. These fuels models include components from vegetable-oil-derived biodiesel, oil-sand derived fuel, alcohol fuels and other advanced bio-based and alternative fuels. (2) Develop detailed chemical kinetic reaction models for mixtures of non-petroleum and petroleum-based components to represent real fuels and lead to efficient reduced combustion models needed for engine modeling codes. (3) Characterize the role of fuel composition on efficiency and pollutant emissions from practical automotive engines.

PItz, W J; Westbrook, C K; Herbinet, O

2009-01-20

408

Idaho Chemical Processing Plant safety document ICPP hazardous chemical evaluation.  

National Technical Information Service (NTIS)

This report presents the results of a hazardous chemical evaluation performed for the Idaho Chemical Processing Plant (ICPP). ICPP tracks chemicals on a computerized database, Haz Track, that contains roughly 2000 individual chemicals. The database contai...

B. J. Harwood

1993-01-01

409

Synthesis of pseudouridine derivatives  

Microsoft Academic Search

There are over one hundred modified nucleosides found in natural RNAs. Among them, pseudouridine is the most common type of modification found abundantly in RNA. Derivatives such as 1-methylpseudouridine, 3-methyl pseudouridine, and 1-methyl-3-(3-amino-3-carboxypropyl)pseudouridine are also found in nature. The overall structural and functional effects of these modified nucleosides remain unclear. Therefore, the study of these modifications is very important. The

Wantanee Sittiwong

2008-01-01

410

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

411

Biomolecule derived nanostructured arrays  

Microsoft Academic Search

During the last decade, intensive research have been reported on biomimetic approaches towards achieving mono-dispersed nanoparticles, and building self-assembled system out of those (organizing nanoparticles). However the development of this research avenue is being hindered by the limited knowledge and very few practical, efficient, cost-effective approaches for implementation of the bio-derived arrays into engineering practice. The objective of this work

Zhen Yuan

2007-01-01

412

Reflexivity in derived categories  

Microsoft Academic Search

An adjoint pair of contravariant functors between abelian categories can be\\u000aextended to the adjoint pair of their derived functors in the associated\\u000aderived categories. We describe the reflexive complexes and interpret the\\u000aachieved results in terms of objects of the initial abelian categories. In\\u000aparticular we prove that, for functors of any finite cohomological dimension,\\u000athe objects of the

Francesca Mantese; Alberto Tonolo

2010-01-01

413

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

414

Chemical analysis of biomass fast pyrolysis oils  

SciTech Connect

This paper reviews the development of the field of chemical analysis of biomass fast pyrolysis oils. The techniques applied to pyrolysis oil analysis are reviewed including proximate and ultimate analysis, water (moisture) analysis, and chemical component analysis by various forms of chromatography, solvent separations, and spectrophotometric analyses, like infrared and ultraviolet. Advanced analytical techniques such as nuclear magnetic resonance and molecular beam -- mass spectrometry are also discussed. This paper reviews and compares the methods and the results of the analyses. The advantages and shortcomings of the various methods applied are identified. Comparisons derived from the IEA Round Robin are incorporated.

Elliott, D.C.

1994-09-01

415

Chemically Prepared Lead Magnesium Niobate Dielectrics  

SciTech Connect

A chemical solution powder synthesis technique has been developed that produces fine uniform powders of lead magnesium niobate (PMN) with 60 to 80 nm crystallite size. The synthesis technique was based on the dissolution of lead acetate and alkoxide precursors in acetic acid followed by precipitation with oxalic acid/propanol solutions. Lead magnesium niobate ceramics fabricated from these chemically derived powders had smaller, more uniform grain size and higher dielectric constants than ceramics fabricated from mixed oxide powders that were processed under similar thermal conditions.

Tuttle, B.A.; Voigt, J.A.; Sipola, D.L.; Olson, W.R.; Goy, D.M.

1998-01-01

416

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

417

Potential Health Hazards of Organic Pigments and Dyes Used in the Manufacture of Paints and Surface Coatings. Appendix I: Scientific Basis for the Proposed Regulation of Dyes Derived from the Chemical Substances Benzidine, 3,3'-Dimethylbenzidine, and 3,3'-Dimethoxybenzidine,  

National Technical Information Service (NTIS)

The scientific bases for regulating dyes derived from benzidine (92875), 3,3'-dimethylbenzidine (119937), and 3,3'-dimethoxybenzidine (119904) are presented. Studies of these compounds have demonstrated that benzidine type dyes undergo nearly complete cle...

C. L. Jenkins

1978-01-01

418

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

419

A new chromone derivative from Berchemia lineata.  

PubMed

To study the chemical constituents from the root of Berchemia lineata (L.) DC., nine compounds were isolated from the EtOAc extract by using silica gel, RP-C18 silica gel column chromatography and preparative HPLC. Based on the spectroscopic analysis, their structures were identified as 5-hydroxy-7-(2'-hydroxypropyl)-2-methyl-chromone (1), (-)-(1'R, 2'S)-erythro-5-hydroxy-7-(1', 2'-dihydroxypropyl)-2-methyl-chromone (2), naringenin (3), eriodictyol (4), (+)-aromadendrin (5), (+)-taxifolin (6), (+)-catechin (7), (+)-epigallocatechin (8) and quercetin (9). Among them, compound 2 is a new chromone derivative. Compound 1 is a known chromone derivative and isolated from this genus for the first time. Compounds 3-9 are known flavonoids and isolated from this plant for the first time. PMID:21348425

Shen, Yu-xia; Teng, Hong-li; Yang, Guang-zhong; Mei, Zhi-nan; Chen, Xiao-long

2010-09-01

420

Chemical abundances for cyanogen-weak giants  

SciTech Connect

Atmospheric parameters and detailed chemical abundances are derived for 30 cyanogen-weak giants. The (Fe/H) ratios range from -1.2 to 0.2, show a mean value of {minus}0.20, and have an estimated internal uncertainty of + or - 0.2. Most of the stars have a modern spectral designation of Fe({minus}); this designation correlates only weakly with the derived (Fe/H) ratio. Light-element abundances and C-12/C-13 ratios are determined for the complete sample. The CNO abundances normalized to Fe collectively do not deviate substantially from that of normal K giants. 94 refs.

Luck, R.E. (Case Western Reserve University, Cleveland, OH (USA))

1991-02-01

421

Relative chemical abundances in different solar regions  

SciTech Connect

Intensities of extreme-ultraviolet emmision lines formed in quiet Sun regions, a coronal hole, an active region, and a prominence are used to derived chemical abundances of carbon, nitrogen, and oxygen relative to silicon in each region. For each element the relative abundance in each region agrees to within the estimated errors in the analysis. This means that the relative abundances are constant over a wide range of electron densities, emission measures, turbulent mass motions, and heights above the limb. Uncertainties in the atomic data appear to be the primary source of scatter in the derived abundances.

Mariska, J.T.

1980-01-01

422

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

Code of Federal Regulations, 2012 CFR

...2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193...2-carboxyethyl)-, N-coco acyl derivs., inner salts. (a) Chemical substance and significant...2-carboxyethyl)-, N-coco acyl derivs., inner salts (PMN P-06-263, Chemical B;...

2012-07-01

423

Hazardous chemicals desk reference  

SciTech Connect

This book supplies instant-access data on nearly 4,700 of the most dangerous chemicals and compounds used in the workplace. It alerts readers to potential short- and long-term hazards by providing for each chemical a 1 to 3 hazard rating ... CAS, NIOSH, and DOT numbers ... concise descriptions of physical properties ... synonyms ... and current standards for exposure limits. A Toxic and Hazard Review (THR) paragraph for each chemical indicates whether the chemical is poisonous, an irritant, corrosive, explosive, or carcinogenic. Special chapters on safety provide clear guidance on the safe handling and storage of chemicals, the use of respirators, the selection of chemical protective clothing, fire protection, and first aid in the workplace.

Sax, N.I.; Lewis, R.J. Sr.

1987-01-01

424

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

425

Policy Manual - Chemical Safety  

Cancer.gov

Keep chemicals properly labeled. Do not remove manufacturer’s label. Hazardous caution labels must be placed on all primary and secondary containers based on information from manufacturer label, MSDS, or chemical inventory evaluation. Always include the name of chemical, lot number, date opened (or date prepared or received), and expiration date and initials, as specified by CAP requirements for each specific area. Each section should follow the labeling requirements of the specific CAP checklist designated for their area.

426

Miniature chemical measurement systems  

SciTech Connect

Prospect of microfabricated monolithic devices that accomplish complete chemical assays is enticing. Early work with microfabricated chemical analysis devices focused on separations methods. More recently reagent manipulation has been integrated with separation devices to create more powerful capabilities. Examples of procedures, other than separations, that have been demonstrated on micromachined structures include reagent mixing, dilution, and reaction, preconcentration through sample stacking and biopolymer tagging for detection. Developments in liquid phase microfabricated chemical analysis devices are reviewed.

Ramsey, J.M.

1996-12-31

427

Trends in information theory-based chemical structure codification.  

PubMed

This report offers a chronological review of the most relevant applications of information theory in the codification of chemical structure information, through the so-called information indices. Basically, these are derived from the analysis of the statistical patterns of molecular structure representations, which include primitive global chemical formulae, chemical graphs, or matrix representations. Finally, new approaches that attempt to go "back to the roots" of information theory, in order to integrate other information-theoretic measures in chemical structure coding are discussed. PMID:24705993

Barigye, Stephen J; Marrero-Ponce, Yovani; Pérez-Giménez, Facundo; Bonchev, Danail

2014-08-01

428

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.

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

2013-01-01

429

A rule-based expert system for chemical prioritization using effects-based chemical categories.  

PubMed

A rule-based expert system (ES) was developed to predict chemical binding to the estrogen receptor (ER) patterned on the research approaches championed by Gilman Veith to whom this article and journal issue are dedicated. The ERES was built to be mechanistically transparent and meet the needs of a specific application, i.e. predict for all chemicals within two well-defined inventories (industrial chemicals used as pesticide inerts and antimicrobial pesticides). These chemicals all lack structural features associated with high affinity binders and thus any binding should be low affinity. Similar to the high-quality fathead minnow database upon which Veith QSARs were built, the ERES was derived from what has been termed gold standard data, systematically collected in assays optimized to detect even low affinity binding and maximizing confidence in the negatives determinations. The resultant logic-based decision tree ERES, determined to be a robust model, contains seven major nodes with multiple effects-based chemicals categories within each. Predicted results are presented in the context of empirical data within local chemical structural groups facilitating informed decision-making. Even using optimized detection assays, the ERES applied to two inventories of >600 chemicals resulted in only ~5% of the chemicals predicted to bind ER. PMID:24779615

Schmieder, P K; Kolanczyk, R C; Hornung, M W; Tapper, M A; Denny, J S; Sheedy, B R; Aladjov, H

2014-04-01

430

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