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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. PMID:24944508

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

2014-01-01

2

Phagocytosis Affects Biguanide Sensitivity of Acanthamoeba spp  

Microsoft Academic Search

The incidence of Acanthamoeba keratitis, a disease associated with contact lens wear, has been in apparent decline with the advent of multipurpose contact lens solutions. The concentrations of the biguanides chlor- hexidine digluconate (CHX) and particularly polyhexamethylene biguanide (PHMB) included in multipurpose solutions (MPSs) are sublethal for amoebae. We evaluated by flow cytometry the effects of these two biguanides on

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

2002-01-01

3

Environmental fate of polyhexamethylene biguanide.  

PubMed

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

Lucas, Anne D

2012-03-01

4

Serine deprivation enhances antineoplastic activity of biguanides.  

PubMed

Metformin, a biguanide widely used in the treatment of type II diabetes, clearly exhibits antineoplastic activity in experimental models and has been reported to reduce cancer incidence in diabetics. There are ongoing clinical trials to evaluate its antitumor properties, which may relate to its fundamental activity as an inhibitor of oxidative phosphorylation. Here, we show that serine withdrawal increases the antineoplastic effects of phenformin (a potent biguanide structurally related to metformin). Serine synthesis was not inhibited by biguanides. Instead, metabolic studies indicated a requirement for serine to allow cells to compensate for biguanide-induced decrease in oxidative phosphorylation by upregulating glycolysis. Furthermore, serine deprivation modified the impact of metformin on the relative abundance of metabolites within the citric acid cycle. In mice, a serine-deficient diet reduced serine levels in tumors and significantly enhanced the tumor growth-inhibitory actions of biguanide treatment. Our results define a dietary manipulation that can enhance the efficacy of biguanides as antineoplastic agents that target cancer cell energy metabolism. Cancer Res; 74(24); 7521-33. ©2014 AACR. PMID:25377470

Gravel, Simon-Pierre; Hulea, Laura; Toban, Nader; Birman, Elena; Blouin, Marie-José; Zakikhani, Mahvash; Zhao, Yunhua; Topisirovic, Ivan; St-Pierre, Julie; Pollak, Michael

2014-12-15

5

Phagocytosis Affects Biguanide Sensitivity of Acanthamoeba spp.  

PubMed Central

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

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

2002-01-01

6

Potential applications for biguanides in oncology  

PubMed Central

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

Pollak, Michael

2013-01-01

7

Polyhexamethylene biguanide dressings in wound management.  

PubMed

This article describes wound management using polyhexamethylene biguanide dressings in two patients experiencing multiple comorbidities. Wound bed debridement and bioburden management were important factors in achieving positive results in terms of promoting wound healing and reducing infection and malodour. PMID:21894678

Fumarola, Sian

8

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

9

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

10

The effect of reactive dyes upon the uptake and anti bacterial action of poly(hexamethylene biguanide) on cotton. Part 2: Uptake of poly(hexamethylene biguanide) on cotton dyed with ?-sulphatoethylsulphonyl reactive dyes  

Microsoft Academic Search

Polyhexamethylene biguanide (PHMB) is a widely used bacteriocide. It is marketed as an aqueous solution of its hydrochloride from which it is readily adsorbed onto cotton, this process depending upon the ability of the cationic PHMB to form electrostatic links with the anionic carboxylate groups present on cotton. The introduction of chemically bound sulphonic acid groups into cotton, which takes

A. Kawabata; J. A. Taylor

2006-01-01

11

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. PMID:24337294

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

2014-01-01

12

Analysis of polyhexamethylene biguanide in multipurpose contact lens solutions.  

PubMed

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

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

2009-12-15

13

Analysis of polyhexamethylene biguanide in multipurpose contact lens solutions  

Microsoft Academic Search

The objective of this study was to establish a reasonably simple and reliable method to measure very low concentrations of polyhexamethylene biguanide (PHMB) in multipurpose contact lens solutions (MPSs). By using a weak cation exchange solid phase extraction cartridge to extract the PHMB from MPS, followed by HPLC analysis using an evaporative light scattering detector, low levels (0.1ppm) of PHMB

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

2009-01-01

14

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

15

Occupationally derived chemicals in breast milk  

SciTech Connect

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

Wolff, M.S.

1983-01-01

16

Production of Chemical Derivatives from Renewables  

SciTech Connect

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

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

1996-06-01

17

Killing acanthamoebae with polyaminopropyl biguanide: quantitation and kinetics.  

PubMed Central

The two Acanthamoeba species most often implicated in corneal keratitis, A. castellanii and A. polyphaga, were exposed as cysts to polyaminopropyl biguanide (PAPB), a commonly used antimicrobial agent. Killing of amoeba cysts was rapid and extensive, with fewer than 2% of either species surviving 30 s of exposure to > or = 45 ppm of PAPB. Killing kinetics were biphasic, and further exposures of 15 min to 1 h killed greater than 90% of those surviving initial killing. This potency of PAPB, together with its low toxicity to humans when ingested or applied topically, underscores the potential of PAPB as an antiamoebic agent. PMID:8031066

Burger, R M; Franco, R J; Drlica, K

1994-01-01

18

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

19

Polyhexamethylene biguanide functionalized cationic silver nanoparticles for enhanced antimicrobial activity  

PubMed Central

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. PMID:22625664

2012-01-01

20

Polyhexamethylene biguanide functionalized cationic silver nanoparticles for enhanced antimicrobial activity.  

PubMed

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. PMID:22625664

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

2012-01-01

21

Double-Biguanide Therapy for Resistant Acanthamoeba Keratitis  

PubMed Central

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

Ferrari, Giulio; Matuska, Stanislav; Rama, Paolo

2011-01-01

22

Cooperativity in the binding of the cationic biocide polyhexamethylene biguanide to nucleic acids  

Microsoft Academic Search

The interaction between the broad-spectrum antimicrobial agent, polyhexamethylene biguanide (PHMB), and various nucleic acids was investigated. Titration of either single- or double-stranded 100-bp DNA, or mixed-molecular weight marker DNA, or tRNA with PHMB caused precipitation of a complex between nucleic acid and PHMB in which the nucleotide\\/biguanide ratio was always close to unity. Binding of PHMB was highly cooperative, with

Michael J Allen; Andrew P Morby; Graham F White

2004-01-01

23

Blue photoluminescence from chemically derived graphene oxide  

Microsoft Academic Search

Fluorescent organic compounds are of significant importance to the development of low-cost opto-electronic devices. Blue fluorescence from aromatic or olefinic molecules and their derivatives is particularly important for display and lighting applications. Thin film deposition of low-molecular-weight fluorescent organic compounds typically requires costly vacuum evaporation systems. On the other hand, solution-processable polymeric counterparts generally luminesce at longer wavelengths due to

Goki Eda; Yun-Yue Lin; Cecilia Mattevi; Hisato Yamaguchi; Hsin-An Chen; I-Sheng Chen; Chun-Wei Chen; Manish Chhowalla

2009-01-01

24

Study of Epigenetic Properties of Poly(HexaMethylene Biguanide) Hydrochloride (PHMB)  

PubMed Central

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

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

2014-01-01

25

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

PubMed

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

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

2014-08-01

26

Determination of chlorhexidine digluconate and polyhexamethylene biguanide in eye drops by capillary electrophoresis with contactless conductivity detection  

Microsoft Academic Search

Polyhexamethylene biguanide hydrochloride (PHMB-HCl) and chlorhexidine digluconate (CHG) are cationic disinfectants widely used in aqueous personal products such as eye drops, lotions and creams. The antiseptics belong to the biguanide group, which are cationic substances well known for their effective action against microbial infection. In this work, capillary electrophoresis combined with contactless conductivity detection was used to determinate these substances

Eva M. Abad-Villar; Susanne F. Etter; Michael A. Thiel; Peter C. Hauser

2006-01-01

27

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

PubMed

The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor. PMID:25662633

Malek, Ali; Balawender, Robert

2015-02-01

28

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

PubMed Central

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

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

2013-01-01

29

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

30

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

31

Relevance of the OCT1 transporter to the antineoplastic effect of biguanides  

SciTech Connect

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

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

2011-11-04

32

Polybiguanides, particularly polyethylene hexamethylene biguanide, have activity against human immunodeficiency virus type 1  

Microsoft Academic Search

Polyhexamethylene biguanide (PHMB) is a polybiguanide (PBG) oligomer with antimicrobial activity that is used extensively and safely as a disinfectant. The reported mechanism of PHMB antimicrobial activity, which involves interactions with cell membrane components, suggested that PHMB or other PBG-based compounds might also have antiviral or virucidal activity against the human immunodeficiency virus type 1 (HIV-1). PHMB had modest in

Fred C. Krebs; Shendra R. Miller; Mary Lee Ferguson; Mohamed Labib; Robert F. Rando; Brian Wigdahl

2005-01-01

33

Analytical Derivation of Moment Equations in Stochastic Chemical Kinetics  

PubMed Central

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

Sotiropoulos, Vassilios; Kaznessis, Yiannis N.

2011-01-01

34

Specific Interactions between the Viral Coreceptor CXCR4 and the Biguanide-Based Compound NB325 Mediate Inhibition of Human Immunodeficiency Virus Type 1 Infection?  

PubMed Central

The present studies were conducted to better define the mechanism of action of polyethylene hexamethylene biguanide (PEHMB) (designated herein as NB325), which was shown in previous studies to inhibit infection by the human immunodeficiency virus type 1 (HIV-1). Fluorescence-activated flow cytometric analyses of activated human CD4+ T lymphocytes exposed to NB325 demonstrated concentration-dependent reductions in CXCR4 epitope recognition in the absence of altered recognition of selected CD4 or CD3 epitopes. NB325 also inhibited chemotaxis of CD4+ T lymphocytes induced by the CXCR4 ligand CXCL12. However, NB325 did not cause CXCR4 internalization (unlike CXCL12) and did not interfere with CXCL12 binding. Additional flow cytometric analyses using antibodies with distinct specificities for extracellular domains of CXCR4 demonstrated that NB325 specifically interfered with antibody binding to extracellular loop 2 (ECL2). This interaction was confirmed using competitive binding analyses, in which a peptide derived from CXCR4 ECL2 competitively inhibited NB325-mediated reductions in CXCR4 epitope recognition. Collectively, these results demonstrate that the biguanide-based compound NB325 inhibits HIV-1 infection by specifically interacting with the HIV-1 coreceptor CXCR4. PMID:19047650

Thakkar, Nina; Pirrone, Vanessa; Passic, Shendra; Zhu, Wei; Kholodovych, Vladyslav; Welsh, William; Rando, Robert F.; Labib, Mohamed E.; Wigdahl, Brian; Krebs, Fred C.

2009-01-01

35

Combined treatment of Acanthamoeba keratitis with propamidine, neomycin, and polyhexamethylene biguanide.  

PubMed

We developed an intensive treatment regimen of topical neomycin, propamidine, and polyhexamethylene biguanide that was tapered to a maintenance level over a 14- to 28-day period as toxicity developed. Since July 1991, we used this treatment on six eyes of five patients in whom Acanthamoeba keratitis was diagnosed clinically. All patients had positive cultures for microorganisms from their corneas or contact lens cases or had pathognomonic findings of pseudodendritic subepithelial infiltrates and radial keratone-uritis. After therapy, all patients improved within two to four weeks, with regression or resolution of neuritis and infiltrates, healing of epithelial defects, and lessening of pain. By three to four months, visual acuity had returned to 20/20 in all eyes. We believe the addition of polyhexamethylene biguanide to our treatment regimen in Acanthamoeba keratitis dramatically aided and hastened the clinical improvement in five consecutive patients and may, with early diagnosis, increase the number of medical cures. PMID:8470718

Varga, J H; Wolf, T C; Jensen, H G; Parmley, V C; Rowsey, J J

1993-04-15

36

Reduced cytotoxicity of polyhexamethylene biguanide hydrochloride (PHMB) by egg phosphatidylcholine while maintaining antimicrobial efficacy  

Microsoft Academic Search

Liposomes or oil-in-water emulsions containing egg yolk phosphatidylcholine (EPC) were combined with aqueous polyhexamethylene biguanide hydrochloride (PHMB). The bactericidal activity of these preparations against Pseudomonas aeruginosa and Staphylococcus aureus as well as their cytotoxicity on cultured murine fibroblasts (L929 cells) was then assayed for either 30min or 60min in the presence of cell culture medium containing 10% fetal bovine serum

Gerald Müller; Axel Kramer; Jürgen Schmitt; Daniela Harden; Torsten Koburger

2011-01-01

37

Biodegradability of end-groups of the biocide polyhexamethylene biguanide (PHMB) assessed using model compounds  

Microsoft Academic Search

Polyhexamethylene biguanide (PHMB), a biocide used in a wide variety of disinfection and preservation applications, is a polydisperse mixture in which the end-groups may be any combination of amine, guanidine and cyanoguanidine. Using PHMB model compounds (1,6-diaminohexane; 1,6-diguanidinohexane; 1,6-di(cyanoguanidino)hexane; 4-guanidinobutyric acid), we have determined the biodegradation characteristics of each end-group in several strains of bacteria isolated for their ability to

Leon P. O’Malley; Andrew N. Collins; Graham F. White

2006-01-01

38

Biguanides inhibit complex I, II and IV of rat liver mitochondria and modify their functional properties.  

PubMed

In this study, we focused on an analysis of biguanides effects on mitochondrial enzyme activities, mitochondrial membrane potential and membrane permeability transition pore function. We used phenformin, which is more efficient than metformin, and evaluated its effect on rat liver mitochondria and isolated hepatocytes. In contrast to previously published data, we found that phenformin, after a 5 min pre-incubation, dose-dependently inhibits not only mitochondrial complex I but also complex II and IV activity in isolated mitochondria. The enzymes complexes inhibition is paralleled by the decreased respiratory control index and mitochondrial membrane potential. Direct measurements of mitochondrial swelling revealed that phenformin increases the resistance of the permeability transition pore to Ca(2+) ions. Our data might be in agreement with the hypothesis of Schäfer (1976) that binding of biguanides to membrane phospholipids alters membrane properties in a non-specific manner and, subsequently, different enzyme activities are modified via lipid phase. However, our measurements of anisotropy of fluorescence of hydrophobic membrane probe diphenylhexatriene have not shown a measurable effect of membrane fluidity with the 1 mM concentration of phenformin that strongly inhibited complex I activity. Our data therefore suggest that biguanides could be considered as agents with high efficacy but low specifity. PMID:24182344

Drahota, Z; Palenickova, E; Endlicher, R; Milerova, M; Brejchova, J; Vosahlikova, M; Svoboda, P; Kazdova, L; Kalous, M; Cervinkova, Z; Cahova, M

2014-01-01

39

Physical and chemical characterization of waste wood derived biochars.  

PubMed

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

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

2015-02-01

40

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

PubMed

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

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

2015-03-15

41

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

42

Metabolic determinants of cancer cell sensitivity to glucose limitation and biguanides  

PubMed Central

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

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

2014-01-01

43

In vitro efficacy of a polyhexamethylene biguanide-impregnated gauze dressing against bacteria found in veterinary patients  

Microsoft Academic Search

Objective - To evaluate the in vitro efficacy of polyhexamethylene biguanide (PHMB)-impregnated gauze dressing in limiting the growth of bacteria both within and underneath the dressing. Study Design - In vitro study. Methods - Squares of PHMB-impregnated and control gauze were placed on agar plates inoculated with 1 of 11 bacterial species, including 8 multi-resistant organisms. Growth under the gauze

William R. Lee; Karen M. Tobias; David A. Bemis; Rohrbach Barton W

2004-01-01

44

Structural evolution during the reduction of chemically derived graphene oxide  

Microsoft Academic Search

The excellent electrical, optical and mechanical properties of graphene have driven the search to find methods for its large-scale production, but established procedures (such as mechanical exfoliation or chemical vapour deposition) are not ideal for the manufacture of processable graphene sheets. An alternative method is the reduction of graphene oxide, a material that shares the same atomically thin structural framework

Akbar Bagri; Cecilia Mattevi; Muge Acik; Yves J. Chabal; Manish Chhowalla; Vivek B. Shenoy

2010-01-01

45

Reduced cytotoxicity of polyhexamethylene biguanide hydrochloride (PHMB) by egg phosphatidylcholine while maintaining antimicrobial efficacy.  

PubMed

Liposomes or oil-in-water emulsions containing egg yolk phosphatidylcholine (EPC) were combined with aqueous polyhexamethylene biguanide hydrochloride (PHMB). The bactericidal activity of these preparations against Pseudomonas aeruginosa and Staphylococcus aureus as well as their cytotoxicity on cultured murine fibroblasts (L929 cells) was then assayed for either 30 min or 60 min in the presence of cell culture medium containing 10% fetal bovine serum as surrogate for wound fluid. We used two assay designs: in the first bactericidal activity and cytotoxicity were determined in separate experiments; in the second both were determined in one experiment. Combining PHMB and EPC containing o/w emulsions or liposomes protects mammalian cells without neutralizing the antiseptic effect. From all tested combinations the o/w emulsions containing 0.05% PHMB proved to be superior in this respect to the aqueous preparation. PMID:21356204

Müller, Gerald; Kramer, Axel; Schmitt, Jürgen; Harden, Daniela; Koburger, Torsten

2011-04-25

46

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

47

The effect of reactive dyes upon the uptake and antibacterial efficacy of poly(hexamethylene biguanide) on cotton. Part 3: Reduction in the antibacterial efficacy of poly(hexamethylene biguanide) on cotton, dyed with bis(monochlorotriazinyl) reactive dyes  

Microsoft Academic Search

The antibacterial efficiency of poly(hexamethylene biguanide), PHMB, on un-dyed cotton has been compared with that of PHMB on cotton coloured with a range of reactive dyes. In each case, the presence of covalently bound dye resulted in a reduction in antibacterial efficiency. In the absence of dye, the cationic PHMB binds to the cotton via weak ion–ion linkages with the

Atsuko Kawabata; John A. Taylor

2007-01-01

48

A simultaneous antimicrobial and shrink resistance treatment of wool woven fabrics using the polymeric biocide polyhexamethylene biguanide  

Microsoft Academic Search

Recently, a novel, effective, and commercially viable antimicrobial treatment for wool was reported that used a peroxymonosulfate\\/sulfite\\u000a pretreatment and the biocide polyhexamethylene biguanide (PHMB). Given the polymeric nature of PHMB used in this antimicrobial\\u000a treatment, this study investigated whether the treatment would also lead to shrink resistance of woven wool fabrics. It was\\u000a shown that up to 5% PHMB (on

Yuan GaoXin; Xin Yu; Anthony P. Pierlot; Ron J. Denning; Robin Cranston

2011-01-01

49

A colorimetric assay for the determination of polyhexamethylene biguanide in pool and spa water using nickel–nioxime  

Microsoft Academic Search

A novel nickel–nioxime analytical method to measure polyhexamethylene biguanide (PHMB) in swimming pools and spas was developed. This method utilizes nickel(II) chloride and 1,2-cyclohexanedionedioxime (nioxime) chemistry. In the method, nickel ions bind and neutralize PHMB in the solution. Excess, un-reacted nickel ions react with nioxime and the resulting colored solution is measured at 550nm using a colorimetric assay. Currently, the

Touraj Rowhani; Anthony F. Lagalante

2007-01-01

50

Assessment of the mode of action of polyhexamethylene biguanide against Listeria innocua by Fourier transformed infrared spectroscopy and fluorescence anisotropy analysis.  

PubMed

Polyhexamethylene biguanide (PHMB) is a cationic biocide. The antibacterial mode of action of PHMB (at concentrations not exceeding its minimal inhibitory concentration) upon Listeria innocua LRGIA 01 was investigated by Fourier transformed infrared spectroscopy and fluorescence anisotropy analysis. Fourier transformed infrared spectra of bacteria treated with or without PHMB presented some differences in the lipids region: the CH(2)/CH(3) (2924 cm(-1)/2960 cm(-1)) band areas ratio significantly increased in the presence of PHMB. Since this ratio generally reflects membrane phospholipids and membrane microenvironment of the cells, these results suggest that PHMB molecules interact with membrane phospholipids and, thus, affect membrane fluidity and conformation. To assess the hypothesis of PHMB interaction with L. innocua membrane phospholipids and to clarify the PHMB mode of action, we performed fluorescence anisotropy experiments. Two probes, 1,6-diphenyl-1,3,5-hexatriene (DPH) and its derivative 1-[4-(trimethyl-amino)-phenyl]-6-phenylhexa-1,3,5-triene (TMA-DPH), were used. DPH and TMA-DPH incorporate inside and at the surface of the cytoplasmic membrane, respectively. When PHMB was added, an increase of TMA-DPH fluorescence anisotropy was observed, but no changes of DPH fluorescence anisotropy occurred. These results are consistent with the hypothesis that PHMB molecules perturb L. innocua LRGIA 01 cytoplasmic membrane by interacting with the first layer of the membrane lipid bilayer. PMID:23210992

Chadeau, Elise; Dumas, Emilie; Adt, Isabelle; Degraeve, Pascal; Noël, Claude; Girodet, Christophe; Oulahal, Nadia

2012-12-01

51

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

PubMed

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

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

2015-01-01

52

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. PMID:20495678

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

2010-01-01

53

Bactericidal core-shell paramagnetic nanoparticles functionalized with poly(hexamethylene biguanide).  

PubMed

Bactericidal paramagnetic particles were obtained either through the attachment of a conjugate of poly(ethyleneimine) (PEI) and poly(hexamethylene biguanide) (PHMBG) to the surface of magnetite (Fe(3)O(4)) particles, or via the sol-gel encapsulation of magnetite particles with a functional silane (3-glycidoxypropyl trimethoxysilane) and subsequent binding of the polysiloxane shell by the amine/imine groups of PHMBG. The encapsulated core-shell particles possess a high saturation magnetization, which is preserved for more than 10 months while in contact with air in aqueous suspensions. The minimum inhibitory concentration (MIC) of the encapsulated particles for eight types of bacteria was size-dependent, with polydisperse submillimeter particles possessing a several-fold higher MIC than analogous particles sized below 250 nm. The encapsulated particles are biocompatible and nontoxic to mammalian cells such as mouse fibroblasts. The particles efficiently bind both glycopeptide components mimicking the gram-positive bacteria membranes and whole bacteria, and possess broad-range bactericidal activity. The cell-particle complexes can be captured, manipulated, and removed by means of a magnet. PMID:21138282

Bromberg, Lev; Chang, Emily P; Hatton, T Alan; Concheiro, Angel; Magariños, Beatriz; Alvarez-Lorenzo, Carmen

2011-01-01

54

Treatment of Acanthamoeba keratitis combined with fungal infection with polyhexamethylene biguanide.  

PubMed

From July 1996 to March 1997, three cases of Acanthamoeba keratitis combined with fungal infection were diagnosed and treated at our ophthalmic department. Specimens from all of these cases were obtained by corneal scraping, keratectomy and anterior chamber paracentesis. The diagnosis was confirmed by either the results of smear test or pathology reports. All of these patients received aggressive treatment with polyhexamethylene biguanide (PHMB) 0.02%, fluconazole, and anegyn eye drops. After the infection had been controlled without extension, therapeutic penetrating keratoplasty was performed on all of these patients despite the existence of infiltration beyond the edge of the graft. Postoperatively, eye drops were tapered gradually, and treatment was continued for 1 to 2 months. All three cases achieved good results and there was no recurrence of infection. Two cases had visual acuity of 20/100 and 20/20, while the other one perceived hand movement only due to later graft rejection. These cases suggest that early diagnosis and immediate use of PHMB and anti-fungal agents are effective in the treatment of Acanthamoeba keratitis combined with fungal infection. PMID:10630064

Tien, S H; Sheu, M M

1999-11-01

55

Determination of polyhexamethylene biguanide hydrochloride using photometric colloidal titration with crystal violet as a color indicator.  

PubMed

A solution of polyhexamethylene biguanide hydrochloride (PHMB-HCl) was titrated with a standard solution of potassium poly(vinyl sulfate) (PVSK) using crystal violet (CV) as an photometric indicator cation. The end point was detected by a sharp absorbance change due to an abrupt decrease in the concentration of CV. A linear relationship between the concentration of PHMB-HCl and the end-point volume of the titrant existed in the concentration range from 2 to 10 × 10(-6) eq mol L(-1). Back-titration was based on adding an excess amount of PVSK to a sample solution containing CV, which was titrated with a standard solution of poly(diallyldimethylammonium chloride) (PDADMAC). The calibration curve of the PHMB-HCl concentration to the end point volume of the titrant was also linear in the concentration range from 2 to 8 × 10(-6) eq mol L(-1). Both photometric titrations were applied to the determination of PHMB-HCl in a few contact-lens detergents. Back-titration showed a clear end point, but direct titration showed an unclear end point. The results of the back-titration of PHMB-HCl were compared with the content registered in its labels. PMID:21828919

Masadome, Takashi; Miyanishi, Takaaki; Watanabe, Keita; Ueda, Hiroshi; Hattori, Toshiaki

2011-01-01

56

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

PubMed

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

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

2014-12-01

57

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

PubMed

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

Dilamian, M; Montazer, M; Masoumi, J

2013-04-15

58

Correlation between chemical structure and rodent repellency of benzoic acid derivatives  

USGS Publications Warehouse

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

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

1965-01-01

59

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

E-print Network

Chemical Vapor Deposition-Derived Graphene with Electrical Performance of Exfoliated Graphene a scalable method to produce large-area graphene, CVD-grown graphene has heretofore exhibited inferior of CVD-grown graphene in which two important sources of disorder, namely grain boundaries and processing

Hone, James

60

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

61

Production of Fatty Acid-Derived Valuable Chemicals in Synthetic Microbes  

PubMed Central

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

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

2014-01-01

62

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

PubMed Central

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

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

2013-01-01

63

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. PMID:12904435

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

2003-01-01

64

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

Microsoft Academic Search

AFM-compatible near-field microwave impedance microscope (MIM), capable of measuring local complex dielectric constant with 100 nm resolution, is used to study graphene in different modalities, with a hierarchy of electrical properties. The low-conductivity graphite oxide and its derivatives show significant electronic inhomogeneity. In the low DC resistance chemically exfoliated graphene sheets, the residual defects lead to appreciable electronics inhomogeneity. In

Worasom Kundhikanjana; Keji Lai; Hailiang Wang; Hongjie Dai; Michael Kelly; Zhi-Xun Shen

2010-01-01

65

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

PubMed

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

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

2009-10-01

66

Organic salts of biguanide - An attempt to crystal engineering of novel materials for second harmonic generation  

NASA Astrophysics Data System (ADS)

Three organic salts of biguanide with oxalic, succinic and L-tartaric acids have been prepared and X-ray structural analysis has been performed. Biguanidium(1+) oxalate hemihydrate ( a = 6.8330(2) Å, b = 10.0430(2) Å, c = 14.6230(4) Å, ? = 90.236(1) , ? = 90.333(1) , ? = 105.605(2) , V = 966.46(4) Å 3, Z = 1, R = 0.0393 for 3704 observed reflections) and biguanidium(1+) hydrogen succinate ( a = 6.4600(1) Å, b = 6.7670(2) Å, c = 11.4150(3) Å, ? = 91.822(1) , ? = 105.312(1) , ? = 90.922(1) , V = 480.89(2) Å 3, Z = 2, R = 0.0357 for 1880 observed reflections) belong to the triclinic space group P 1¯. Their crystal structures are based on biguanidium(1+) pairs connected by intermolecular N-H⋯N hydrogen bonds. The remaining ions (eventually water molecules) form a 3D structural network with these pairs. Furthermore, the formation of the cationic and anionic layers interconnected by intermolecular N-H⋯O hydrogen bonds was observed in the crystal structure of biguanidium(1+) hydrogen succinate. Biguanidium(2+) L-tartrate crystallizes in the orthorhombic space group P 2 12 12 1 ( a = 6.7170(2) Å, b = 9.2740(2) Å, c = 16.1500(4) Å, V = 1006.04(4) Å 3, Z = 4, R = 0.0432 for 2193 observed reflections). The crystal structure is based on L-tartrate chains, which are interconnected by isolated biguanidium(2+) cations via several types of N-H⋯O hydrogen bonds. The formation of L-tartrate chains is mediated by two types of intermolecular O-H⋯O hydrogen bonds connecting the hydroxyl and carboxylate groups. The FTIR and FT Raman spectra of all the compounds were recorded and discussed. The theoretical values of the first hyperpolarizability components were calculated for biguanidium(1+) and biguanidium(2+) cations at the B3LYP level with the 6-311G(d,p) basis set. Quantitative measurements of the second harmonic generation of powdered biguanidium(2+) L-tartrate at 800 nm were performed and a relative efficiency of 2% (compared to KDP) was observed. The thermal behaviour of all the prepared compounds was studied by the DSC method in the temperature interval from 90 K up to a temperature close to the melting points of the crystals. The FTIR and FT Raman spectra of biguanidium(2+) L-tartrate were investigated down to 130 K.

Matulková, Irena; N?mec, Ivan; Císa?ová, Ivana; N?mec, Petr; Van?k, P?emysl

2010-03-01

67

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

SciTech Connect

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

Watson, A.P.

2003-07-24

68

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. PMID:23196792

Xu, Peng; Loomis, James; Panchapakesan, Balaji

2013-01-01

69

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

SciTech Connect

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

Kundhikanjana, W.

2010-06-02

70

Use of chemical genomics in assessment of the UPR.  

PubMed

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

Saito, Sakae; Tomida, Akihiro

2011-01-01

71

Interaction of polyhexamethylene biguanide hydrochloride (PHMB) with phosphatidylcholine containing o/w emulsion and consequences for microbicidal efficacy and cytotoxicity.  

PubMed

Oil-in-water (o/w) emulsions containing egg yolk phosphatidylcholine (EPC) were combined with aqueous polyhexamethylene biguanide hydrochloride (PHMB). The PHMB concentration in the aqueous phase was estimated by filtration centrifugation experiments. In parallel, PHMB concentration was assessed utilizing cytotoxicity assays (neutral red) on cultured murine fibroblasts (L929 cells) and tests of bactericidal efficacy on either Pseudomonas aeruginosa or Staphylococcus aureus. Biological tests were performed in cell culture medium. Filtration centrifugation experiments demonstrated much higher aqueous PHMB concentrations than did the assays for biologically effective PHMB. Therefore, biological test systems should preferably be used to verify effective PHMB concentrations. Tests of microbicidal efficacy in which the same 0.05% PHMB o/w emulsion was re-used 8 times revealed a drug delivery system activated by the presence of test bacteria. PMID:23313712

Müller, Gerald; Koburger, Torsten; Kramer, Axel

2013-01-25

72

Chemical constituents of Prangos tschiniganica; structure elucidation and absolute configuration of coumarin and furanocoumarin derivatives with anti-HIV activity.  

PubMed

The methanol extract of the dried aerial parts of Prangos tschimganica gave three new coumarin derivatives and 30 known coumarin derivatives. Their structures were established on the basis of chemical and spectroscopic evidence. Absolute configuration of the isolated compounds were determined by using a modified Mosher's method. Some of the isolated compounds showed anti-HIV activity. PMID:11456095

Shikishima, Y; Takaishi, Y; Honda, G; Ito, M; Takfda, Y; Kodzhimatov, O K; Ashurmetov, O; Lee, K H

2001-07-01

73

Chemical and Molecular Aspects on Interactions of Galanthamine and Its Derivatives with Cholinesterases.  

PubMed

Dual action of galanthamine as potent cholinesterase inhibitor and nicotinic modulator has attracted a great attention to be used in the treatment of AD. Consequently, galanthamine, a natural alkaloid isolated from a Galanthus species (snowdrop, Amaryllidaceae), has become an attractive model compound for synthesis of its novel derivatives to discover new drug candidates. Numerous studies have been done to elucidate interactions between galanthamine and its different derivatives and the enzymes; acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) using in vitro and in silico experimental models. The in vitro studies revealed that galanthamine inhibits AChE in strong, competitive, long-acting, and reversible manner as well as BChE, although its selectivity towards AChE is much higher than BChE. The in silico studies carried out by employing molecular docking experiments as well as molecular dynamics simulations pointed out to existence of strong interactions of galanthamine with the active gorge of AChE, mostly of Torpedo californica (the Pasific electric ray) origin. In this review, we evaluate the mainstays of cholinesterase inhibitory action of galanthamine and its various derivatives from the point of view of chemical and molecular aspects. PMID:25483718

Gulcan, H Ozan; Orhan, Ilkay Erdogan; Sener, Bilge

2014-12-01

74

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

SciTech Connect

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

David C. Dayton

2010-03-24

75

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

PubMed

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

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

2014-01-01

76

Characterization of trimethylsilyl derivatives of cerebrosides by direct inlet-chemical ionization mass spectrometry.  

PubMed

Submicrogram quantities of trimethylsilyl derivatives of cerebrosides obtained from the spleen of a patient with Gaucher's disease and from bovine brain were analyzed by direct probe inlet-chemical ionization mass spectrometry, using isobutane as the reagent gas. Quasimolecular ions (QM+, M + 73) and other recognizable fragment ions produced by the successive elimination of trimethylsilanol and sugar residue gave useful information about fatty acid compositions. These ions could also be utilized for qualitative analyses of the molecular species of cerebrosides. Cerebrosides with non-hydroxy and hydroxy fatty acids could be discriminated from each other by comparing the intensities of their quasimolecular ions. Cerebrosides with saturated and monounsaturated fatty acids could also be discrimnated from each other, because the mass number decreased by two mass units in cerebrosides with monounsaturated fatty acids. It was concluded that structural information and molecular species determination could be obtained from small amounts of purified cerebrosides. PMID:650093

Murata, T; Ariga, T; Oshima, M; Miyatake, T

1978-03-01

77

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

PubMed

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

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

2014-11-17

78

Fatty Acid-Derived Biofuels and Chemicals Production in Saccharomyces cerevisiae  

PubMed Central

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

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

2014-01-01

79

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

PubMed

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

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

2014-01-01

80

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

81

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

82

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

PubMed Central

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

Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette

2014-01-01

83

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

SciTech Connect

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 ({sup 1}H) NMR spectroscopy to 'speciate' Ti(IV) in inflammatory SF. Treatment of osteoarthritic SF samples with increasing concentrations of Ti(IV) (0.10-1.03 mM [TiO(C{sub 2}O{sub 4}){sub 2}]{sup 2-}) gave rise to a specific broadening of the citrate proton resonances, indicating that this bioavailable oxygen-donor ligand plays an important role in complexing implant-derived Ti(IV). {sup 1}H NMR analysis of Ti(IV)-loaded SF samples subsequently treated with a large excess of ascorbate (0.05 M) showed that this added Ti(IV) chelator was only poorly effective in removing this metal ion from Ti(IV)-citrate/Ti(IV)-oxycitrate complexes. The results obtained here provide evidence for complexation of the low-molecular-mass (non-protein-bound) fraction of implant-derived Ti(IV) by citrate in vivo.

Silwood, Christopher J.L. [Department of Applied Science, Faculty of Engineering, Science and the Built Environment, London South Bank University, 103 Borough Road, London SE1 0AA (United Kingdom); Grootveld, Martin [Department of Applied Science, Faculty of Engineering, Science and the Built Environment, London South Bank University, 103 Borough Road, London SE1 0AA (United Kingdom)]. E-mail: grootvm@lsbu.ac.uk

2005-05-13

84

Antifungal activities of polyhexamethylene biguanide and polyhexamethylene guanide against the citrus sour rot pathogen Geotrichum citri-aurantii in vitro and in vivo  

Microsoft Academic Search

Polyhexamethylene biguanide (PHMB) and polyhexamethylene guanide (PHMG) are broad-spectrum antibacterial agents. Experiments were conducted to investigate the antifungal activities of PHMB and PHMG against a major citrus sour rot pathogen Geotrichum citri-aurantii both in vitro and in vivo. PHMG and PHMB treatments significantly inhibited arthroconidia germination and mycelial growth of G. citri-aurantii in vitro. PHMG and PHMB at 5mg\\/L inhibited

Linyan Feng; Fuwang Wu; Jing Li; Yueming Jiang; Xuewu Duan

2011-01-01

85

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

NASA Astrophysics Data System (ADS)

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

Xin, Le

86

Block copolymer-derived monolithic polymer films and membranes comprising self-organized cylindrical nanopores for chemical sensing and separations.  

PubMed

Microphase separation of block copolymers (BCPs) has been extensively studied because it leads to the self-assembled formation of periodic structures controlled on the scale of tens of nanometers. In particular, BCP-derived cylindrical microdomains have attracted considerable interest for various applications owing to their well-defined shapes of uniform and tunable diameters. This focus review highlights recent efforts to apply BCP-derived monolithic films/membranes comprising cylindrical nanopores for chemical sensing and separations. The nanopores provide confined molecular pathways that exhibit enhanced selectivity based on steric, electrostatic, and chemical interactions, and thus, enable us to design unique electrochemical sensors and highly efficient separation membranes. PMID:24909553

Ito, Takashi

2014-10-01

87

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

88

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

89

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. PMID:16507455

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

90

Chemical genetics-based discovery of indole derivatives as HCV NS5B polymerase inhibitors.  

PubMed

In order to identify the inhibitors of hepatitis C virus (HCV) replication with a novel scaffold via a mechanistically unbiased approach, we screened our in-house library composed of ?6000 compounds with various chemical structures by using the renilla luciferase-linked genotype 2a reporter virus, and we identified a series of compounds containing an indole moiety that were active against HCV replication. Based on this result, we further synthesized three groups of indole derivatives and evaluated their inhibitory effects on HCV replication. In the present structure-activity relationship study of these indole derivatives, we discovered that compound 12e was the most potent inhibitor of HCV replication with minimal cytotoxicity (EC50 = 1.1 ?M, EC90 = 2.1 ?M, and CC50 = 61.8 ?M). We also confirmed that compound 12e caused a dose- and time-dependent reduction of viral RNA as well as viral protein levels in both genotype 2a J6/JFH1 RNA-transfected cells and genotype 1b Bart79I subgenomic replicon cells. Finally, a genetic mapping study of mutant viruses resistant to compound 12e revealed that NS5B RNA polymerase was the potential target. This finding was further validated by demonstration of inhibition of NS5B RNA polymerase in vitro by compound 12e (IC50 = 292 nM). Compound 12e may serve as a valuable candidate for the development of a new class of HCV NS5B RNA polymerase inhibitors in the future. PMID:24561671

Jin, Guanghai; Lee, Sungjin; Choi, Moonju; Son, Seohyun; Kim, Geon-Woo; Oh, Jong-Won; Lee, Choongho; Lee, Kyeong

2014-03-21

91

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

92

13C chemical-shift anisotropy of alkyl-substituted aromatic carbon in anthracene derivatives.  

PubMed

The (13)C chemical-shift anisotropy in anthracene derivatives (9,10-dimethylanthracene, 9,10-dihydroanthracene, dianthracene, and triptycene) has been measured by the 2D FIREMAT timed pulse sequence and the corresponding set of principal values has been determined by the TIGER processing method. These molecules expand the data base of (13)C CSA measurements of fused aromatic rings some bridged by sp(3) carbon resulting in an unusual bonding configuration, which leads to distinctive aromatic (13)C CSA values. Crystal lattice distortions to the CSA were observed to change the isotropic shift by 2.5 to 3.3 ppm and changes as large as 8.3 ppm in principal components. Modeling of the CSA data by GIPAW DFT (GGA-PBE/ultrafine) shielding calculations resulted in an rms chemical-shift distance of 2.8 ppm after lattice including geometry optimization of the diffraction structures by the GIPAW method at GGA-PBE/ultrafine level. Attention is given to the substituted aromatic carbon in the phenyl groups (here forth referred to as the ?-carbon) with respect to CSA modeling with electronic methods. The (13)C CSA of this position is accurately determined due to its spectral isolation of the isotropic shift that limits overlap in the FIREMAT spectrum. In cases where the bridging ring is sp(3) carbon, the current density is reduced from extending beyond the peripheral phenyl groups; this plays a significant role in the magnetic shielding of the ?-position. Nuclear independent chemical-shift calculations based on GIAO DFT (B3LYP/6-31G(d)) shielding calculations were used to model the intramolecular ?-interactions in dianthracene and triptycene. These NICS results estimate the isotropic shift of the ?-position in dianthracene to be insignificantly affected by the presence of the neighboring aromatic rings. However, a notable change in isotropic shielding, ??(iso)=-2.1 ppm, is predicted for the ?- position of triptycene. Experimentally, the ?22 principal component at the ?-position for both dianthracene and triptycene increases by at least 12 ppm compared to 9,10-dihydroanthracene. To rationalize this change, shielding calculations in idealized structures are explored. The spatial position of the bicyclic scaffolding of the bridging ring plays a key role in the large increase in ?22 for the ?-carbon. PMID:23477865

Hoop, Cody L; Iuliucci, Robbie J

2013-06-01

93

Imaging-based chemical screens using normal and glioma-derived neural stem cells.  

PubMed

The development of optimal culture methods for embryonic, tissue and cancer stem cells is a critical foundation for their application in drug screening. We previously described defined adherent culture conditions that enable expansion of human radial glia-like fetal NS (neural stem) cells as stable cell lines. Similar protocols proved effective in the establishment of tumour-initiating stem cell lines from the human brain tumour glioblastoma multiforme, which we termed GNS (glioma NS) cells. Others have also recently derived more primitive human NS cell lines with greater neuronal subtype differentiation potential than NS cells, which have similarities to the early neuroepithelium, named NES (neuroepithelial stem) cells. In the present paper, we discuss the utility of these cells for chemical screening, and describe methods for a simple high-content live-image-based platform. We report the effects of a panel of 160 kinase inhibitors (Inhibitor Select I and II; Calbiochem) on NES cells, identifying three inhibitors of ROCK (Rho-associated kinase) as promoting the expansion of NES cell cultures. For the GNS cells, we screened a panel of 1000 compounds and confirmed our previous finding of a cytotoxic effect of modulators of neurotransmitter signalling pathways. These studies provide a framework for future higher-throughput screens. PMID:20659005

Danovi, Davide; Falk, Anna; Humphreys, Peter; Vickers, Richard; Tinsley, Jon; Smith, Austin G; Pollard, Steven M

2010-08-01

94

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

PubMed

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

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

2014-07-16

95

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

96

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. PMID:23429350

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

2013-01-01

97

Chemical and mineralogical evaluation of slag products derived from the pyrolysis/melting treatment of MSW  

SciTech Connect

This paper provides the results of studies on the characteristics of novel material derived from pyrolysis/melting treatment of municipal solid waste in Japan. Slag products from pyrolysis/melting plants were sampled for the purpose of detailed phase analysis and characterization of heavy metal-containing phases using optical microscopy, electron probe microanalysis (EPMA), XRF and XRD. The study revealed that the slag material contains glass (over 95%), oxide and silicate minerals (spinel, melilite, pseudowollastonite), as well as individual metallic inclusions as the major constituents. A distinct chemical diversity was discovered in the interstitial glass in terms of silica content defined as low and high silica glass end members. Elevated concentrations of Zn, Cr, Cu, Pb and Ba were recorded in the bulk composition. Cu, Pb and Ba behave as incompatible elements since they have been markedly characterized as part of polymetallic alloys and insignificantly sulfides in the form of spherical metallic inclusions associated with tracer amounts of other elements such as Sb, Sn, Ni, Zn, Al, P and Si. In contrast, an appreciable amount of Zn is retained by zinc-rich end members of spinel and partially by melilite and silica glass. Chromium exhibits similar behavior, and is considerably held by Cr-rich spinel. The intense incorporation of Zn and Cr into spinel indicates the very effective enrichment of these two elements into phases more environmentally resistant than glass. There was no evidence, however, that Cu and Pb enter into the structure of the crystalline silicates or oxides that may lead to their easier leachability upon exposure to the environment.

Saffarzadeh, Amirhomayoun [Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan)]. E-mail: a_saffarzadeh@yahoo.com; Shimaoka, Takayuki [Institute of Environmental Systems, Department of Urban and Environmental Engineering, Faculty of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Motomura, Yoshinobu [Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Watanabe, Koichiro [Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan)

2006-07-01

98

Characterization of high-k HfO2 films prepared using chemically modified alkoxy-derived solutions  

NASA Astrophysics Data System (ADS)

The HfO2 films were prepared using alkoxy-derived precursor solutions. The effects of the chemical composition of precursor solutions on the microstructure development and electrical properties were investigated. The flatness and refractive index of the HfO2 films were improved by using diethanolamine-added solution. This result is considered to be due to the difference in the progress of organic decomposition and the behavior of nucleation and grain growth. The difference in the chemical composition affected the electrical properties such as leakage current and capacitance-voltage characteristics, which are related to the defects in the film and interface state.

Suzuki, Kazuyuki; Kato, Kazumi

2009-03-01

99

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

100

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 PMID:23009652

2012-01-01

101

Increased Peritoneal Dialysis Exit Site Infections Using Topical Antiseptic Polyhexamethylene Biguanide Compared to Mupirocin: Results of a Safety Interim Analysis of an Open-Label Prospective Randomized Study  

PubMed Central

Prophylactic mupirocin for peritoneal catheter exit sites reduces exit site infection (ESI) risk but engenders antibiotic resistance. We present early interim safety analysis of an open-label randomized study comparing polyhexamethylene biguanide (PHMB) and mupirocin. A total of 106 patients randomized to 53 in each group were followed up for a mean of 12.68 months per patient. On safety analysis, the PHMB group had a significantly greater ESI rate than the mupirocin group (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.09 to 0.80), leading to discontinuation of the trial. PMID:23403425

Findlay, Andrew; Serrano, Charelle; Punzalan, Sally

2013-01-01

102

Increased peritoneal dialysis exit site infections using topical antiseptic polyhexamethylene biguanide compared to mupirocin: results of a safety interim analysis of an open-label prospective randomized study.  

PubMed

Prophylactic mupirocin for peritoneal catheter exit sites reduces exit site infection (ESI) risk but engenders antibiotic resistance. We present early interim safety analysis of an open-label randomized study comparing polyhexamethylene biguanide (PHMB) and mupirocin. A total of 106 patients randomized to 53 in each group were followed up for a mean of 12.68 months per patient. On safety analysis, the PHMB group had a significantly greater ESI rate than the mupirocin group (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.09 to 0.80), leading to discontinuation of the trial. PMID:23403425

Findlay, Andrew; Serrano, Charelle; Punzalan, Sally; Fan, Stanley L

2013-05-01

103

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

104

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

PubMed

In this paper the relationship between the chemical structure and fluorescence characteristics of 30 phenylquinolinylethyne (PhQE), and phenylisoquinolinylethyne (PhIE) derivatives compounds employing ab initio calculations have been elucidated. Quantum chemical calculations (6-31G) were carried out to obtain: the optimized geometry, energy levels, charges and dipole moments of these compounds, in the singlet (steady and excited states) and triplet states. The relationship between quantum chemical descriptors, and wavelength of maximum excitation and emission indicated that these two parameters have the most correlation with quantum chemical hardness (eta). Also, stokes shift has the most correlation with the square of difference between the maximum of positive charges in the singlet steady and singlet excited states. The quantitative structure-property relationship (QSPR) of PhQE and PhIE was studied for relative fluorescence intensity (RFI). The genetic algorithm (GA) was applied to select the variables that resulted in the best-fit models. After the variable selection, multiple linear regression (MLR) and support vector machine (SVM) were both utilized to construct linear and non-linear QSPR models, respectively. The SVM model demonstrated a better performance than that of the MLR model. The route mean square error (RMSE) in the training and the test sets for the SVM model was 0.195 and 0.324, and the correlation coefficients were 0.965 and 0.960, respectively, thus revealing the reliability of this model. The resulting data indicated that SVM could be used as a powerful modeling tool for QSPR studies. According to the best of our knowledge, this is the first research on QSPR studies to predict RFI for a series of PhQE and PhIE derivative compounds using SVM. PMID:19854100

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

2009-12-01

105

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

106

Facilitating Biomimetic Syntheses of Borrerine Derived Alkaloids by Means of Flow-Chemical Methods  

E-print Network

Flow chemistry, although now commonly used for general synthetic chemistry, has not been applied extensively in a biomimetic fashion. Here we show how the flow syntheses of borrerine derived alkaloids can use these principles to obtain complex...

Kamptmann, Sonja B.; Ley, Steven V.

2014-01-01

107

Bioactivity and chemical synthesis of caffeic acid phenethyl ester and its derivatives.  

PubMed

Caffeic acid phenethyl ester (CAPE), as one of the main active ingredients of the natural product propolis, shows the unique biological activities such as anti-tumor, anti-oxidation, anti-inflammatory, immune regulation, and so on. These have attracted the attention of many researchers to explore the compound with potent biological activities. This review aims to summarize its bioactivities, synthetic methods and derivatives, which will be helpful for further study and development of CAPE and its derivatives. PMID:25314606

Zhang, Pengxuan; Tang, Yuping; Li, Nian-Guang; Zhu, Yue; Duan, Jin-Ao

2014-01-01

108

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

PubMed Central

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

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

2013-01-01

109

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

Microsoft Academic Search

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

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

1980-01-01

110

Effects of organic chemicals derived from ambient particulate matter on lung inflammation related to lipopolysaccharide  

Microsoft Academic Search

The effects of components of ambient particulate matter (PM) on individuals with predisposing respiratory disorders are not well defined. We have previously demonstrated that airway exposure to diesel exhaust particles (DEP) or organic chemicals (OC) extracted from DEP (DEP–OC) enhances lung inflammation related to bacterial endotoxin (lipopolysaccharide, LPS). The present study aimed to examine the effects of airway exposure to

Ken-ichiro Inoue; Hirohisa Takano; Rie Yanagisawa; Seishiro Hirano; Takahiro Kobayashi; Takamichi Ichinose; Toshikazu Yoshikawa

2006-01-01

111

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

112

Quantitative structure-activity relationship (QSAR) for a series of novel cannabinoid derivatives using descriptors derived from semi-empirical quantum-chemical calculations.  

PubMed

Recent work implicating the cannabinoid receptors in a wide range of human pathologies has intensified the need for reliable QSAR models for drug discovery and lead optimization. Predicting the ligand selectivity of the cannabinoid CB(1) and CB(2) receptors in the absence of generally accepted models for their structures requires a ligand-based approach, which makes such studies ideally suited for quantum-chemical treatments. We present a QSAR model for ligand-receptor interactions based on quantum-chemical descriptors (an eQSAR) obtained from PM3 semi-empirical calculations for a series of phenyl-substituted cannabinoids based on a ligand with known in vivo activity against glioma [Duntsch, C.; Divi, M. K.; Jones, T.; Zhou, Q.; Krishnamurthy, M.; Boehm, P.; Wood, G.; Sills, A.; Moore. B. M., II. J. Neuro-Oncol., 2006, 77, 143] and a set of structurally similar adamantyl-substituted cannabinoids. A good model for CB(2) inhibition (R(2)=0.78) has been developed requiring only four explanatory variables derived from semi-empirical results. The role of the ligand dipole moment is discussed and we propose that the CB(2) binding pocket likely possesses a significant electric field. Describing the affinities with respect to the CB(1) receptor was not possible with the current set of ligands and descriptors, although the attempt highlighted some important points regarding the development of QSAR models. PMID:19250829

Ferreira, Antonio M; Krishnamurthy, Mathangi; Moore, Bob M; Finkelstein, David; Bashford, Donald

2009-03-15

113

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

PubMed Central

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

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

2013-01-01

114

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

115

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

SciTech Connect

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

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

1981-01-01

116

Paleoclimatic significance of chemical weathering in loess-derived paleosols of subarctic central Alaska  

USGS Publications Warehouse

Chemical weathering in soils has not been studied extensively in high-latitude regions. Loess sequences with modern soils and paleosols are present in much of subarctic Alaska, and allow an assessment of present and past chemical weathering. Five sections were studied in detail in the Fairbanks, Alaska, area. Paleosols likely date to mid-Pleistocene interglacials, the last interglacial, and early-to-mid-Wisconsin interstadiale. Ratios of mobile (Na, Ca, Mg, Si) to immobile (Ti or Zr) elements indicate that modern soils and most interstadial and interglacial paleosols are characterized by significant chemical weathering. Na2O/TiO2 is lower in modern soils and most paleosols compared to parent loess, indicating depletion of plagioclase. In the clay fraction, smectite is present in Tanana and Yukon River source sediments, but is absent or poorly expressed in modern soils and paleosols, indicating depletion of this mineral also. Loss of both plagioclase and smectite is well expressed in soils and paleosols as lower SiO 2/TiO2. Carbonates are present in the river source sediments, but based on CaO/TiO2, they are depleted in soils and most paleosols (with one exception in the early-to-mid-Wisconsin period). Thus, most soil-forming intervals during past interglacial and interstadial periods in Alaska had climatic regimes that were at least as favorable to mineral weathering as today, and suggest boreal forest or acidic tundra vegetation. ?? 2008 Regents of the University of Colorado.

Muhs, D.R.; Ager, T.A.; Skipp, G.; Beann, J.; Budahn, J.; McGeehin, J.P.

2008-01-01

117

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

PubMed Central

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

Shen, Yang; Bax, Ad

2015-01-01

118

A comprehensive and compact n-heptane oxidation model derived using chemical lumping.  

PubMed

A detailed reaction mechanism for n-heptane oxidation has been compiled and subsequently simplified. The model is based on a kinetic model for C1-C4 fuel oxidation of Hoyermann et al. [Phys. Chem. Chem. Phys., 2004, 6, 3824] and a detailed mechanism for n-heptane oxidation developed by Curran et al. [Combust. Flame, 1998, 114, 149]. The generated mechanism is kept compact by limiting the application of the low temperature oxidation pathways to the fuel molecule. The first reaction steps and the complex low temperature paths in the oxidation process have been simplified and reorganized by linear chemical lumping. The reported procedure allows a decrease in number of species and reactions with only a minor loss of model accuracy. The simplified model is of very compact size and gives an advantageous starting point for further model reduction. By this chemically lumped general mechanism without further adjustments the large set of experimental data for the high and low temperature oxidation (ignition delay times, species concentration profiles, heat release and engine pressure profiles, flame speeds and flame structure data) for conditions ranging from very low to high temperatures (550-2300 K), very lean to extremely fuel rich (0.22 < phi < 3) mixtures and pressures between 1 and 42 bar is consistently described providing a basis for reliable predictions for future applications, (i) building reaction mechanisms for similar but chemically more complex fuels (e.g. iso-octane, n-decane,...) and (ii) calculating complex flow fields ("fluid dynamics") after further simplification with advanced reduction tools. PMID:17311154

Ahmed, Syed Sayeed; Mauss, Fabian; Moréac, Gladys; Zeuch, Thomas

2007-03-01

119

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

PubMed Central

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

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

2014-01-01

120

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

121

pH dependence of individual tryptophan N-1 hydrogen exchange rates in lysozyme and its chemically modified derivatives.  

PubMed

Nuclear magnetic resonance analyses have been made of the individual hydrogen-deuterium exchange rates of tryptophan indole N-1 hydrogens in native lysozyme and its chemically modified derivatives including lysozyme with an ester cross-linkage between Glu-35 and Trp-108, lysozyme with an internal amide cross-linking between the epsilon-amino group of Lys-13 and the alpha-carboxyl group of Leu-129, and lysozyme with the beta-aspartyl sequence at Asp-101. The pH dependence curves of the exchange rates for Trp-63 and Trp-108 are different from those expected for tryptophan. The pH dependence curve for Trp-108 exchange exhibits the effects from molecular aggregation at pH above 5 and from a transition between the two conformational fluctuations at around pH 4. The exchange rates for tryptophan residues in native lysozyme and modified derivatives are not correlated with the thermodynamic or kinetic parameters in protein denaturation, suggesting that the fluctuations responsible for the exchange are not global ones. The exchange rates for tryptophan residues remote from the modification site are perturbed. Such tryptophan residues are found to be involved in a small but distinct conformational change due to the modification. Therefore, the perturbations of the N-1 hydrogen exchange rates are related to the minor change in local conformation or in conformational strain induced by the chemical modification. PMID:3593697

Endo, T; Ueda, T; Yamada, H; Imoto, T

1987-04-01

122

First total chemical synthesis of natural acyl derivatives of some phenolglycosides of the family Salicaceae.  

PubMed

The total synthesis of certain natural phenolglycosides of the family Salicaceae, namely: salireposide, populosides A, B, and C and not occurring in plants desoxysalireposide (2-(?-D-glucopyranosyloxy)-benzylbenzoate) and per-acetate of iso-salireposide (2-(?-D-glucopyranosyloxy)-5-benzoyloxy benzyl alcohol), starting from readily available phenols and glucose was accomplished. A simple method for the synthesis of phenolglycosides derivatives of 2-acyloxy salicyl and gentisyl alcohol was developed. The key step of these natural products' synthesis is a selective removal of acetyl groups in the presence of other acyl groups. PMID:23123575

Belyanin, Maxim L; Stepanova, Elena V; Ogorodnikov, Vladimir D

2012-12-01

123

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

124

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

SciTech Connect

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

Stewart, M.K.; Lyon, G.L.; Robinson, B.W. (DSIR Physical Sciences, Nuclear Sciences Group, P.O. Box 31-132, Lower Hutt (NZ)); Glover, R.B. (DSIR Chemistry, Wairakei, Private Bag, Taupo (NZ))

1992-04-01

125

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

PubMed Central

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

2014-01-01

126

Cervicovaginal Safety of the Formulated, Biguanide-Based Human Immunodeficiency Virus Type 1 (HIV-1) Inhibitor NB325 in a Murine Model  

PubMed Central

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

127

Chemically derived defects in zinc oxide nanocrystals and their enhanced photo-electrocatalytic activities.  

PubMed

This paper reports the influence of surface defects on the photocatalytic degradation of methylene blue (MB) for zinc oxide (ZnO) nanocrystals (NCs) synthesized in different organic solvents. A simple chemical approach has been adopted for the promotion of oxygen vacancies in pristine ZnO using solvents namely dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and dimethylsulfoxide (DMSO). This alters the growth of NCs through the promotion of oxygen vacancies depending on the fact that the solvent with minimum viscosity supports faster nucleation and growth exhibiting maximum surface defects. DMF with minimum viscosity results in largest particle size and superior photocatalytic activity. Further, X-ray diffraction, UV-visible reflectance spectroscopy and transmission electron microscopy confirm that the DMF supports the faster growth of NCs as compared to NMP and DMSO. Electron paramagnetic resonance, Raman, X-ray photoelectron, and photoluminescence spectroscopies confirm different states of oxygen vacancies in the NCs and their dependence on the nature of solvents. The photocatalytic activities of these NCs were investigated against the degradation of MB as a model dye. The results show that the oxygen defects at the surface of NCs are more responsible for higher photocatalytic activity than the specific surface area of NCs. The electrochemical investigations of MB degradation suggest that these defects upon interaction with MB influence the storage capacity and charge-discharge profiles of NCs. During degradation, MB passivates these defects, which has been explained in terms of increased charge-discharge time and storage capacity. PMID:25183397

Prakash, Anand; Bahadur, D

2014-10-21

128

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

SciTech Connect

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

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

1999-07-01

129

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

PubMed

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

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

2002-01-01

130

Chemical and enzymatic approaches to carbohydrate-derived spiroketals: di-D-fructose dianhydrides (DFAs).  

PubMed

Di-D-fructose dianhydrides (DFAs) comprise a unique family of stereoisomeric spiro-tricyclic disaccharides formed upon thermal and/or acidic activation of sucrose- and/ or D-fructose-rich materials. The recent discovery of the presence of DFAs in food products and their remarkable nutritional features has attracted considerable interest from the food industry. DFAs behave as low-caloric sweeteners and have proven to exert beneficial prebiotic nutritional functions, favouring the growth of Bifidobacterium spp. In the era of functional foods, investigation of the beneficial properties of DFAs has become an important issue. However, the complexity of the DFA mixtures formed during caramelization or roasting of carbohydrates by traditional procedures (up to 14 diastereomeric spiroketal cores) makes evaluation of their individual properties a difficult challenge. Great effort has gone into the development of efficient procedures to obtain DFAs in pure form at laboratory and industrial scale. This paper is devoted to review the recent advances in the stereoselective synthesis of DFAs by means of chemical and enzymatic approaches, their scope, limitations, and complementarities. PMID:18794777

García-Moreno, M Isabel; Benito, Juan M; Mellet, Carmen Ortiz; Fernández, José M García

2008-01-01

131

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

PubMed

The prevalent use of soil fumigants has resulted in air pollution in some agricultural regions. Our previous research showed that application of thiosulfate fertilizers at the soil surface may offer an effective and economical approach to reduce the emission of halogenated fumigants via a chemical remediation process. In this fumigant emission-reduction strategy, volatile 1,3-dichloropropene (1,3-D) reacts with thiosulfate to generate a nonvolatile Bunte salt (thiosulfate derivative of 1,3-D). However, the decomposition of the Bunte salt may be associated with the production of perceptible odors. This study investigated the stability of this reaction product in different environmental media. Hydrolysis experiments demonstrated that the thiosulfate derivative was relatively stable in neutral and moderately acidic aqueous solutions. In contrast, the thiosulfate derivative was readily converted to a dialkyl disulfide via a base hydrolysis process in pH 10 buffer solution. In a strongly acidic solution, a mercaptan and a dialkyl disulfide compound were detected as two primary hydrolysis products. In soil, this initial reaction product underwent a series of biotic conversions to generate several volatile or semivolatile organic sulfur compounds. The formation and distribution of four volatile/semivolatile products in the air and soil were detected in different soils treated with the thiosulfate derivative of 1,3-D. This study indicated that odors occurring in soil treated with halogenated fumigants and thiosulfate fertilizers might arise from the generation and release of these and other volatile/semivolatile organic sulfur products. The environmental fate and effects of such volatile/semivolatile sulfur compounds should be considered in the application of sulfur-containing fertilizers in fumigated fields. PMID:17948793

Zheng, Wei; Gan, Jay; Papiernik, Sharon K; Yates, Scott R

2007-09-15

132

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

133

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

PubMed Central

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

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

1962-01-01

134

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

135

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, E. Arthur, III; Been, J.; McGeehin, J.P.

2001-01-01

136

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

NASA Astrophysics Data System (ADS)

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

Sarmecanic, James Richard

1997-12-01

137

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

NASA Astrophysics Data System (ADS)

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

Shokry, H.

2014-02-01

138

Furan derivatives of substituted phenylthiourea: spectral studies, semi-empirical quantum-chemical calculations and X-ray structure analyses  

NASA Astrophysics Data System (ADS)

Fifty new derivatives of 1-(furan-2-carbonyl)- and 1-(furan-3-carbonyl)-3-phenyl substituted thiourea have been synthesised and identified. Intramolecular hydrogen bonds were investigated in detail, using IR spectroscopy. The three-level Fermi resonance effect in the IR spectra was analysed after deconvolution and band separation. Semi-empirical quantum-chemical calculations (AM1 and PM3) support the results of the IR spectroscopic studies. X-ray single crystal diffraction analyses of four selected compounds, namely 1-(furan-3-carbonyl)-3-(2-trifluoromethyl-phenyl)-thiourea ( 1e), 1-(2-methyl-furan-3-carbonyl)-3-(2-trifluoromethyl-phenyl)-thiourea ( 2e), 1-(2,6-dichloro-phenyl)-3-(2-methyl-furan-3-carbonyl)-thiourea ( 2n) and 1-(4-methoxyphenyl)-3-(3-methyl-2-furan-carbonyl)-thiourea ( 3e), corroborated the molecular and crystal structure of these compounds. Relatively strong intramolecular hydrogen bonds of the N-H⋯O dbnd6 C type as well as intermolecular two-centred and bifurcated three-centred hydrogen bonds were observed, confirming the results of the IR spectral study and the semi-empirical quantum-chemical calculations. A variety of intermolecular interactions, yielding the supramolecular architectures in the four crystalline compounds, are discussed in detail.

Hritzová, Ol'ga; ?ernák, Juraj; Šafa?, Peter; Fr?hlichová, Zdenka; Cs?regh, Ingeborg

2005-05-01

139

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

140

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

141

Persistent Interactions between Biguanide-Based Compound NB325 and CXCR4 Result in Prolonged Inhibition of Human Immunodeficiency Virus Type 1 Infection ?  

PubMed Central

We previously demonstrated that the biguanide-based compound NB325 inhibits human immunodeficiency virus type 1 (HIV-1) infection by interacting with the CXCR4 viral coreceptor. This interaction also appeared to be persistent, since HIV-1 infection was inhibited even when the virus was introduced subsequent to the removal of NB325 from the cell culture medium. The present studies were conducted to determine the extent and mechanism of this prolonged antiviral activity. Persistent inhibition of HIV-1 infection by NB325 was concentration dependent and was apparent up to 8 h after removal of the compound. Flow cytometric analyses of stimulated CD4+ T lymphocytes exposed to NB325 demonstrated concentration-dependent reductions in CXCR4 extracellular loop 2 epitope recognition that were maintained up to 24 h after removal of the compound. CXCL12-induced chemotaxis was also persistently inhibited following pre-exposure to NB325. These results demonstrate that persistent inhibition of X4 HIV-1 infection by NB325 involves extended perturbation of the viral coreceptor CXCR4. PMID:20231400

Thakkar, Nina; Pirrone, Vanessa; Passic, Shendra; Keogan, Shawn; Zhu, Wei; Kholodovych, Vladyslav; Welsh, William; Rando, Robert; Labib, Mohamed; Wigdahl, Brian; Krebs, Fred C.

2010-01-01

142

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

143

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

144

Physico-chemical factors influencing the shikonin derivatives production in cell suspension cultures of Arnebia euchroma (Royle) Johnston, a medicinally important plant species.  

PubMed

Cell suspension cultures of Arnebia euchroma were raised from in vitro leaf-derived friable callus on liquid MS [Murashige and Skoog] medium supplemented with BAP (6-benzylaminopurine) (10.0 ?M) and IBA (indole-3-butyric acid) (5.0 ?M). A two-stage culture system was employed using growth and production medium for cell biomass and shikonin derivatives, respectively. Factors such as light, temperature, sucrose and pH (hydrogen ion concentration) were studied to observe their effect on the shikonin derivative production. Light conditions completely inhibited shikonin derivative production. Out of different temperature regimes tested, the highest yield (586.17 ?g/g FW) was found at 25°C. Maximum production (656.14 ?g/g FW) was observed in 6% sucrose. An alkaline pH (7.25-9.50) favoured shikonin derivative production. The results showed that physical and chemical factors greatly influence the production of shikonin derivatives in cell suspension cultures of A. euchroma. Therefore, by employing optimum culture conditions, it is possible to enhance the production of secondary compounds from the cells. The factors optimized for in vitro production of shikonin derivatives during the present study can successfully be employed for their large-scale production in bioreactors. PMID:20977433

Malik, Sonia; Bhushan, Shashi; Sharma, Madhu; Singh Ahuja, Paramvir

2011-02-01

145

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

PubMed

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

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

2014-10-01

146

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

PubMed Central

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

2011-01-01

147

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

PubMed

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

Monreal, Carlos M; Schnitzer, Morris

2011-01-01

148

Reconstitution of anti-allergic activities of PG102 derived from Actinidia arguta by combining synthetic chemical compounds.  

PubMed

PG102, a water-soluble extract from an edible fruit, Actinidia arguta, has previously been shown to control various factors involved in allergy pathogenesis. It was investigated whether the original activities of PG102 could be reconstituted by mixing chemical compounds present in PG102. Six compounds present in PG102 were, individually or in the form of mixtures, tested for their effects on the expression of various Th2 cytokines and inflammatory mediators in the cell-based assay. Each chemical inhibited IL-4 expression to varying degrees. The chemical compounds were combined at a ratio present in PG102, resulting in two formulations, CQMIIH and CQM, consisting of all or the first three of the following chemicals, citric, quinic, and malic acids, myo-inositol, isoquercitrin, and 5-hydroxymethyl-2-furaldehyde. The mixtures reconstituted original activities of PG102 to a significant level. In the murine asthma model, CQM ameliorated asthmatic symptoms and significantly decreased the level of IgE and IL-5. The decreased phosphorylation of ERK1/2 was observed in cells and mice treated with PG102 and the mixtures. Our data indicated that the substantial portion of PG102's anti-allergic activities could be reconstituted, in vitro and in vivo, by mixing six chemical compounds, suggesting the possibility of developing a new type of anti-allergic agent. This approach may be useful for developing chemically defined functional products from complex botanical extracts. PMID:23918875

Kim, Donghyun; Choi, Jinyong; Kim, Mi-Jeong; Kim, Seon Hee; Cho, Sang Heon; Kim, Sunyoung

2013-06-01

149

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

SciTech Connect

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

Schwartz, Justin; Holmuhamedov, Ekhson; Zhang, Xun; Lovelace, Gregory L.; Smith, Charles D. [Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC (United States); Lemasters, John J., E-mail: JJLemasters@musc.edu [Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC (United States); Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC (United States)

2013-11-15

150

Chemical analysis of flavonoid constituents of the seagrass Halophila stipulacea: First finding of malonylated derivatives in marine phanerogams  

Microsoft Academic Search

The flavonoid fraction from the butanol extract of a Mediterranean sample of the seagrass Halophila stipulacea was chemically analyzed. A new malonylated flavone glucoside, genkwanin-4?-O-(6“-malonyl-glucopyranoside) (3), was isolated together with known flavone glucosides 4-9, previously reported only from terrestrial sources. The structure of 3 was established by means of spectroscopic techniques, mainly NMR methods.

Fatma Bitam; Maria Letizia Ciavatta; Marianna Carbone; Emiliano Manzo; Ernesto Mollo; Margherita Gavagnin

2010-01-01

151

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

152

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

153

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

PubMed

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

Stan, Catalina; Stefanache, Alina; Dumitrache, M

2006-01-01

154

Chemical composition and complex refractive index of Saharan Mineral Dust at Izaña, Tenerife (Spain) derived by electron microscopy  

Microsoft Academic Search

Samples from two strong homogeneous dust plumes from the Saharan desert reaching Izaña (Tenerife, Spain) in July and August 2005 were taken with a miniature impactor system and filter samplers. Size, aspect ratio and chemical composition of more than 22,000 individual particles were studied by scanning electron microscopy. The mineralogical phase composition of about 200 particles was investigated by transmission

Konrad Kandler; Nathalie Benker; Ulrich Bundke; Emilio Cuevas; Martin Ebert; Peter Knippertz; Sergio Rodríguez; Lothar Schütz; Stephan Weinbruch

2007-01-01

155

Availability of protein-derived amino acids as feedstock for the production of bio-based chemicals  

Microsoft Academic Search

This review describes different potential sources for amino acids that could be used for the production of bulk chemicals in a biorefinery, such as agricultural byproduct streams. Volumes at which these sources and the amino acids therein are available were determined, and the most interesting amino acids in terms of their potential available quantity were identified. The investigated sources are

T. M. Lammens; M. C. R. Franssen; E. L. Scott; J. P. M. Sanders

2012-01-01

156

Urea derivatives on the move: cytokinin-like activity and adventitious rooting enhancement depend on chemical structure.  

PubMed

Urea derivatives are synthetic compounds, some of which have proved to be positive regulators of cell division and differentiation. N-phenyl-N'-(2-chloro-4-pyridyl)urea (forchlorofenuron, CPPU) and N-phenyl-N'-(1,2,3-thiadiazol-5-yl)urea (thidiazuron, TDZ), well known urea cytokinin representatives, are extensively used in in vitro plant morphogenesis studies, as they show cytokinin-like activity often exceeding that of adenine compounds. In recent years, renewed interest in structure-activity relationship studies allowed identification of new urea cytokinins and other urea derivatives that specifically enhance adventitious root formation. In this review, we report the research history of urea derivatives, new insights into their biological activity, and recent progress on their mode of action. PMID:19470099

Ricci, A; Bertoletti, C

2009-05-01

157

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

Microsoft Academic Search

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

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

2004-01-01

158

Redox chemistry and chemical biology of H2S, hydropersulfides, and derived species: Implications of their possible biological activity and utility.  

PubMed

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

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

2014-12-01

159

Transients due to instabilities hinder Kardar-Parisi-Zhang scaling: a unified derivation for surface growth by electrochemical and chemical vapor deposition.  

PubMed

We propose a unified moving boundary problem for surface growth by electrochemical and chemical vapor deposition, which is derived from constitutive equations into which stochastic forces are incorporated. We compute the coefficients in the interface equation of motion as functions of phenomenological parameters. The equation features the Kardar-Parisi-Zhang (KPZ) nonlinearity and instabilities which, depending on surface kinetics, can hinder the asymptotic KPZ scaling. Our results account for the universality and the experimental scarcity of KPZ scaling in the growth processes considered. PMID:11736462

Cuerno, R; Castro, M

2001-12-01

160

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

SciTech Connect

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

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

1980-01-01

161

Insights on the susceptibility of plant pathogenic fungi to phenazine-1-carboxylic acid and its chemical derivatives.  

PubMed

Pseudomonas chlororaphis subsp. aureofaciens strain M71 produced two phenazine compounds as main secondary metabolites. These metabolites were identified as phenazine-1-carboxylic acid (PCA) and 2-hydroxyphenazine (2-OH P). In this study, the spectrum of the activity of PCA and 2-OH P was evaluated against a group of crop and forestal plant pathogenic fungi by an agar plate bioassay. PCA was active against most of the tested plant pathogens, while 2-OH P slightly inhibited a few fungal species. Furthermore, four semisynthesised derivatives of PCA (phenazine-1-carboxymethyl, phenazine-1-carboxamide, phenazine-1-hydroxymethyl and phenazine-1-acetoxymethyl) were assayed for their antifungal activity against 11 phytopathogenic species. Results showed that the carboxyl group is a structural feature important for the antifungal activity of PCA. Since the activity of phenazine-1-carboxymethyl and phenazine-1-carboxamide, the two more lipophilic and reversible PCA derivatives remained substantially unaltered compared with PCA. PMID:22724439

Puopolo, Gerardo; Masi, Marco; Raio, Aida; Andolfi, Anna; Zoina, Astolfo; Cimmino, Alessio; Evidente, Antonio

2013-01-01

162

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

163

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

164

Biogenic synthesis, purification, and chemical characterization of anti-inflammatory resolvins derived from docosapentaenoic acid (DPAn-6).  

PubMed

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

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

2009-05-29

165

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

166

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

PubMed

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

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

2013-10-01

167

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

168

Derived No-effect Levels (DNELs) under the European Chemicals Regulation REACH-An Analysis of Long-term Inhalation Worker-DNELs Presented by Industry.  

PubMed

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

Schenk, Linda; Deng, Uriell; Johanson, Gunnar

2014-12-01

169

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

170

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

171

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

PubMed

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

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

2014-10-28

172

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

PubMed

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

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

2015-01-24

173

Photoluminescence studies of silver-exchanged cadmium selenide crystals. Modification of a chemical sensor for aniline derivatives by heterojunction formation  

NASA Astrophysics Data System (ADS)

Single-crystal n-CdSe surfaces have been modified by an exchange reaction with aqueous Ag(+) that converts part of the surface to Ag2Se and releases Cd2(+) to solution. Formation of Ag2Se is established by x ray powder diffraction. The ESCA and Auger spectroscopy are consistent with the formation of Ag2Se islands having thicknesses of 0 to 500 A, depending on reaction conditions. Steady-state photoluminescence (PL) experiments show that Ag(+)-exchanged CdSe (CdSe/Ag(+)) can be superior to CdSe as an aniline sensor: ring-substituted aniline derivatives in toluene solution cause enhancements of the CdSe band edge PL in CdSe/Ag(+) samples relative to a toluene ambient, with the effect about twice as large as for unexchanged CdSe. The variations in PL intensity of CdSe/Ag(+) are well fit by a dead-layer model, allowing estimation of the adduct-induced change in depletion width.

Leung, Larry K.; Komplin, Norma J.; Ellis, Arthur B.; Tabatabaie, Ned

1991-05-01

174

Improved anti-inflammatory activity of three new terpenoids derived, by systematic chemical modifications, from the abundant triterpenes of the flowery plant Calendula officinalis.  

PubMed

Rings A, D and E of faradiol (1), and ring E of both arnidiol (10) and calenduladiol (4) have been subjected to various selective chemical manipulations to modify polarity, water affinity, H-bonding, sterics, and number of aromatic groups of these anti-inflammatory natural compounds. A total of 15 new and four known pentacyclic triterpenoids have been obtained in this way. Some 13 terpenoids were evaluated for their topical anti-inflammatory activities with respect to inhibition of croton oil induced ear oedema in mouse. Three derivatives of 1, the C(16) benzyl ether 15, the C(30) aldehyde 24, and the C(30) primary alcohol 25 showed significantly improved anti-inflammatory potencies, which is relevant for (future) structure-activity-relationship (SAR) studies. PMID:17192009

Neukirch, Hannes; D'Ambrosio, Michele; Sosa, Silvio; Altinier, Gianmario; Della Loggia, Roberto; Guerriero, Antonio

2005-05-01

175

Negative ion chemical ionization gas chromatography/mass spectrometry and gas chromatography/tandem mass spectrometry of prostanoid pentafluorobenzyl ester/methoxime/trimethylsilyl ether derivatives.  

PubMed

Negative ion chemical ionization mass spectra of prostaglandin F2 alpha, prostaglandin E2, prostaglandin D2, 6-oxo-prostaglandin F1 alpha, 2,3-dinor-6-oxo-prostaglandin F1 alpha, thromboxane B2, 2,3-dinor-thromboxane B2, and 11-dehydro-thromboxane B2 pentafluorobenzyl ester (PFB)/methoxime/trimethylsilyl ether derivatives are presented. Collisionally activated decomposition mass spectra of the [M-PFB]- ions at collision energies of 8-24 eV and argon collision gas pressures of 1-2m Torr almost show only fragmentation of trimethylsilanol, (CH3)2Si = CHOH, (CH3)2Si = CH2 and methanol whereas, except for carbon dioxide loss, only few low-intensity fragments from the carbon skeleton of the prostanoids are observed. PMID:3365491

Schweer, H; Seyberth, H W; Meese, C O; Fürst, O

1988-02-01

176

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

177

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

PubMed

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

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

2014-12-01

178

Chemical solution deposition derived (001)-oriented epitaxial BiFeO3 thin films with robust ferroelectric properties using stoichiometric precursors (invited)  

NASA Astrophysics Data System (ADS)

Phase pure bismuth ferrite (BiFeO3) thin films with (001)-oriented epitaxial structure are realized on lanthanum strontium manganite (La0.67Sr0.33MnO3) buffered (001)-SrTiO3 substrates by chemical solution deposition. The annealing process is optimized such that a stoichiometric precursor can be used to accurately control the Bi:Fe ratio. Ferroelectric, dielectric, and resistive switching behaviours are investigated for 40 nm, 70 nm, and 150 nm BFO thin films. While the thinnest film (40 nm) shows very leaky loops, square and fully saturated polarization hysteresis loops are shown for the thicker films. The highest remanent polarization (2Pr = 100 ?C/cm2) and relative dielectric constant (?r = 613) are obtained in the 150 nm BFO thin film. High cycle fatigue tests show that the thick films are resistant to polarization fatigue. Piezoresponse force microscopy results show that the domain structure varies with thickness. Resistive switching and polarization mediated diode effects are also observed. These robust properties suggest that chemical solution deposition derived BiFeO3 thin films can offer a viable low cost alternative.

Zhang, Qi; Valanoor, Nagarajan; Standard, Owen

2014-08-01

179

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

180

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

PubMed Central

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

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

2013-01-01

181

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

182

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

PubMed Central

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

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

2014-01-01

183

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

184

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

PubMed

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

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

2015-01-01

185

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

PubMed

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

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

2014-11-26

186

Clinopyroxenes in high-P metaperidotites from Happo-O'ne, central Japan: Implications for wedge-transversal chemical change of slab-derived fluids  

NASA Astrophysics Data System (ADS)

The metaperidotites found in the Happo-O'ne region of central Japan are mostly lherzolites to harzburgites with subordinate dunites. Their protoliths originated as a series of refractory residues by near-fractional melting, 15-25% melting in the spinel field, which is confirmed by a HREE melting model of the apparently primary clinopyroxene. These metaperidotites display U-shaped primitive mantle (PM)-normalized REE patterns (0.02-0.5 times PM) and are highly enriched in LILE (0.2-20 times PM) relative to HFSE (< 0.2 times PM), providing evidence for mantle-wedge metasomatism. In-situ analyses confirmed that clinopyroxenes and tremolite are enriched in fluid-mobile elements (B, Sr, Pb, Li, Cs, Ba and Rb; 0.1-100 times PM) coupled with depletion of HFSE (Ta, Hf, Th, Zr, Ti and Nb; < 0.7 times PM) + U; these chemical features of clinopyroxenes and tremolite are similar to those of their whole rocks, and reflect slab-fluid metasomatism. We recognized three stages of clinopyroxenes that are different in morphology and REE patterns, but show the same major-element chemistry. Nearly euhedral clinopyroxene (Cpx1) displays a spoon-shaped REE pattern (0.2-3 times PM), reflecting the first stage (stage 1) of metasomatism. Acicular clinopyroxene (Cpx2) after tremolite + olivine shows a U-shaped REE pattern (0.06-1 times PM) (stage 2), whereas fine-grained clinopyroxene (Cpx3) derived from orthopyroxene shows very low concentrations of REE (stage 3). These three successive stages of retrogressive clinopyroxene formation possibly denote a retrogressive chemical change of the involved fluids during multi-stage metasomatism. The fluid of stage 1 is highly enriched in LREE (0.2-2 times PM), MREE, Pb, Sr, Li and Rb relative to the stage-3 fluid that is very low in MREE, Pb, LREE and Sr, but has high Na, Mn, Ba, B and Cs. The stage-2 fluid, which is low in LREE (0.06-1 times PM), Li and Pb, and very low in Cs, Rb and Hf relative to the fluid of stage 1, is considered to be a transitional fluid between stages 1 and 3. The retrogressive change of the fluid composition is possibly equivalent to a transversal change of the slab-derived fluid within the mantle wedge due to a change of metamorphic condition, depth of the subducting slab and an episode of metasomatism during the exhumation of the Happo-O'ne peridotites.

Khedr, Mohamed Zaki; Arai, Shoji; Tamura, Akihiro; Morishita, Tomoaki

2010-10-01

187

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

SciTech Connect

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

Haibo Zhao; Liming Liu; Baowen Wang; Di Xu; Linlin Jiang; Chuguang Zheng [Huazhong University of Science and Technology, Wuhan (China). State Key Laboratory of Coal Combustion

2008-03-15

188

Chemical microsensors  

DOEpatents

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

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

1995-01-01

189

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

190

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

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

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

PubMed

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

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

2011-05-01

193

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

194

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

195

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

196

Structure-based predictions of 13C-NMR chemical shifts for a series of 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indoles derivatives using GA-based MLR method  

NASA Astrophysics Data System (ADS)

Experimental values for the 13C NMR chemical shifts (ppm, TMS = 0) at 300 K ranging from 96.28 ppm (C4' of indole derivative 17) to 159.93 ppm (C4' of indole derivative 23) relative to deuteride chloroform (CDCl3, 77.0 ppm) or dimethylsulfoxide (DMSO, 39.50 ppm) as internal reference in CDCl3 or DMSO-d6 solutions have been collected from literature for thirty 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indole derivatives containing different substituted groups. An effective quantitative structure-property relationship (QSPR) models were built using hybrid method combining genetic algorithm (GA) based on stepwise selection multiple linear regression (SWS-MLR) as feature-selection tools and correlation models between each carbon atom of indole derivative and calculated descriptors. Each compound was depicted by molecular structural descriptors that encode constitutional, topological, geometrical, electrostatic, and quantum chemical features. The accuracy of all developed models were confirmed using different types of internal and external procedures and various statistical tests. Furthermore, the domain of applicability for each model which indicates the area of reliable predictions was defined.

Ghavami, Raouf; Sadeghi, Faridoon; Rasouli, Zolikha; Djannati, Farhad

2012-12-01

197

Chemical Evolution  

E-print Network

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

Francesca Matteucci

2007-04-05

198

Sticky Windows: Chemical and Biological Characteristics of the Organic Film Derived from Particulate and Gas-Phase Air Contaminants Found on an Urban Impervious Surface  

Microsoft Academic Search

A novel environmentally derived mixture that integrates exposure to atmospherically derived gas- and particle-phase compounds\\u000a in urban areas—namely, the organic film that develops as a thin layer on urban impervious surfaces—was investigated for its\\u000a ability to induce gene expression via the aryl hydrocarbon receptor (AhR). The organic film on window glass from 21 sites\\u000a in downtown Toronto (Ontario, Canada) was

E. M. Hodge; M. L. Diamond; B. E. McCarry; G. A. Stern; P. A. Harper

2003-01-01

199

Glycal Derivatives  

NASA Astrophysics Data System (ADS)

Glycals are unsaturated sugar derivatives in which the double bond engages the anomeric carbon atom. Such cyclic vinyl ethers are characterized by high reactivity, allowing for regio- and stereoselective transformations, directly or indirectly related to glycosylation, as well as to formation of carbon-carbon and carbon-heteroatom bonds at the anomeric center. This review provides a systematic survey of chemical synthetic methods, by which the carbon-carbon double bond is introduced next to the ring oxygen, in an endo- or exocyclic position. Some mechanistic aspects are discussed in relation to traditional methods of glycal preparation, which rely on elimination reactions. Glycal-to-glycal rearrangement and applications of organometallic chemistry and heteroatom-induced transformations for syntheses and activation of glycals are also highlighted.

Priebe, Waldemar; Fokt, Izabela; Grynkiewicz, Grzegorz

200

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

201

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...

202

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. PMID:24454574

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

2013-01-01

203

Determination of binding strength for the supramolecular complexation of a designed bisporphyrin with C 60, C 70 and their derivatives employing absorption spectrophotometric, fluorescence and quantum chemical calculations  

NASA Astrophysics Data System (ADS)

The present paper reports the synthesis of a designed bisporphyrin ( 1), and its supramolecular complexes with C 60, C 70 and their derivatives, namely, tert-butyl-(1,2-methanofullerene)-61-carboxylate ( 2) and [6,6]-phenyl C 70 butyric acid methyl ester ( 3) in toluene medium. C 60, C 70 and their derivatives undergo ground state non-covalent interaction with 1 is evidenced from absorption spectrophotometric study in which it is observed that the intensity of the Soret absorption band of 1 decreases considerably in presence of C 60, C 70 and their derivatives. Steady state fluorescence studies reveal efficient quenching of fluorescence of 1 in presence of fullerenes. The binding constant ( K) values of the fullerene/ 1 complexes follows the trend: 2/ 1 < C 60/ 1 < 3/ 1 < C 70/ 1. However, selectivity in K values of the bisporphyrin complexes is found to be higher for fullerene derivatives in comparison to C 60 and C 70. Time resolved emission studies establish relatively long-lived charge separated state for the C 70/ 1 complex. Molecular mechanics calculations at force field model in vacuo evoke the single projection geometric structures of various fullerene/ 1 complexes and interpret their stability differences in terms of heat of formation values.

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

2011-09-01

204

40 CFR 721.1820 - Bisphenol derivative.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Bisphenol derivative. 721.1820 Section 721.1820...Substances § 721.1820 Bisphenol derivative. (a) Chemical substance and significant...substance identified generically as bisphenol derivative (PMN No. P-92-509) is...

2010-07-01

205

40 CFR 721.5913 - Phenothiazine derivative.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

206

40 CFR 721.9658 - Thiadiazole derivative.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

207

Studies on cardiac ingredients of plants. IX. Chemical transformation of proscillaridin by utilizing its 1,4-cycloadducts as key compounds and biological activities of their derivatives.  

PubMed

Three aromatic compounds (2-4) possessing a carbomethoxyl group or a dimethoxyphthaloyl group, prepared by the Diels-Alder reaction of the cardiac glycoside, proscillaridin (1), with dimethyl acetylenedicarboxylate and methyl propiolate, were transformed into alcohols, carboxylic acids and amides. The biological activities of the resulting derivatives were evaluated by the use of Na+, K(+)-adenosine triphosphatase (Na+,K(+)-ATPase) from dog kidney and isolated guinea-pig papillary muscle. Although the biological activities of the resulting derivatives were less potent than that of 1, a para-substituted benzylalcohol (5), methylbenzamides (9a and 10a), and ethylbenzamides (9b and 10b) inhibited the activity of Na+,K(+)-ATPase almost as potently as naturally occurring cardiac glycosides such as digoxin and digitoxin. PMID:1318790

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

1992-02-01

208

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

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

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

2013-06-30

209

STEM and EDXS characterisation of physico-chemical reactions at the periphery of sol-gel derived Zn-substituted hydroxyapatites during interactions with biological fluids  

PubMed Central

With its good properties of biocompatibility and bioactivity hydroxyapatite (HA) is highly used as bone substitutes and as coatings on metallic prostheses. In order to improve bioactive properties of HA we have elaborated Zn2+ doped hydroxyapatite. Zn2+ ions substitute for Ca2+ cations in the HA structure and four Zn concentrations (Zn/Zn+Ca) were prepared 0.5, 1, 2, 5 % at. To study physico-chemical reactions at the materials periphery, we immersed the bioceramics into biological fluids for delays from 1 day to 20 days. The surface changes were studied at the nanometer scale by scanning transmission electron microscopy associated to energy dispersive X-ray spectroscopy. After 20 days of immersion we observed the formation of a calcium-phosphate layer at the periphery of the HA doped with 5% of zinc. This layer contains magnesium and its thickness was around 200 nm. Formation of this Ca-P-Mg layer represents bioactivity properties of the 5% Zn-substituted hydroxyapatite. This biologically active layer improves properties of HA and will permit a chemical bond between the ceramic and bone. PMID:15893220

Jallot, Edouard; Nedelec, Jean-Marie; Grimault, Anne S.; Chassot, Emmanuelle; Grandjean-Laquerriere, Alexia; Laquerriere, Patrice; Laurent-Maquin, Dominique

2005-01-01

210

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

211

Sticky windows: chemical and biological characteristics of the organic film derived from particulate and gas-phase air contaminants found on an urban impervious surface.  

PubMed

A novel environmentally derived mixture that integrates exposure to atmospherically derived gas- and particle-phase compounds in urban areas-namely, the organic film that develops as a thin layer on urban impervious surfaces-was investigated for its ability to induce gene expression via the aryl hydrocarbon receptor (AhR). The organic film on window glass from 21 sites in downtown Toronto (Ontario, Canada) was found to contain a complex mixture of environmental contaminants typical of urban environments, notably PAHs, n-alkanes, PCBs, organochlorine (OC) pesticides, and polar constituents. Using a stably transfected reporter cell line, we found that the crude extract of organic film induces AhR-dependent gene expression in a dose-dependent fashion. Three subfractions of the crude extract induced significant luciferase expression: nonpolar aromatic > polar aromatic > nonpolar aliphatic. Recombination of the fractions did not lead to recovery of the full activity of the crude extract, which may indicate that some of the compounds lost during fractionation were significant contributors to the induction observed with the crude extract. The interactions between a tonic dose of B[ a]P (10(-7) M) and each of the aromatic fractions were determined to be antagonistic following analysis by the method of isoboles. Our results suggest that organic film makes up a diverse array of compounds active at the AhR and that these compounds may not interact in a strictly additive manner. PMID:12712271

Hodge, E M; Diamond, M L; McCarry, B E; Stern, G A; Harper, P A

2003-05-01

212

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.

213

Lead-free piezoelectric (K0.5Na0.5)NbO3 thin films derived from chemical solution modified with stabilizing agents  

NASA Astrophysics Data System (ADS)

(K0.5Na0.5)NbO3 (KNN)-based ferroelectric thin films were prepared by a chemical solution approach modified with both diethanolamine (DEA) and ethylenediaminetetraacetic acid (EDTA) as the stabilizing agents. The obtained KNN thin films exhibited a remarkably low leakage current and well-saturated polarization hysteresis loop. The effective piezoelectric strain coefficient d33 and voltage coefficient g33 under the clamping of the substrate were improved to 74.0 pm/V and 28.3 mm V/N, respectively. The reason for the superior properties was found that the addition of EDTA and DEA was effective in suppressing the volatilization of K and Na at moderate temperature before the crystallization.

Goh, Phoi Chin; Yao, Kui; Chen, Zhong

2010-09-01

214

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

215

Cyclodextrin derivative of hyaluronan  

Microsoft Academic Search

Conversion of hyaluronan (HA) to its ?-cyclodextrin derivative (HA-?-CD) was accomplished by direct coupling of ?-cyclodextrin (?-CD) molecules with carboxylic acid groups of the HA macromolecule. The intermolecular dehydration, yielding the HA-?-CD derivative, was performed by the action of diethyl azodicarboxylate and triphenylphosphine under mild, neutral conditions. The physico-chemical characteristics of the novel (bio)material, determined both in solution and solid

L. Šoltés; R. Mendichi; E. Machovà; B. Steiner; J. Alföldi; V. Sasinkovà; S. Bystrický; K. Balog

1999-01-01

216

Expression analysis of immune-related genes in CD34(+) progenitor-derived dendritic cells after exposure to the chemical contact allergen DNCB.  

PubMed

We studied the changes in gene expression after exposure of human dendritic cells (DCs) to the model allergen dinitrochlorobenzene (DNCB). DCs were derived from CD34(+) progenitor cells of three different donors and exposed to 10 microM DNCB or solvent for several time intervals (3, 6 and 12h). cDNA microarrays were used to assess the transcriptional activity of 11,000 human genes. Compared to control gene expression, changes larger than +/-two-fold were observed for 241 genes after exposure to DNCB. Of these genes, 137 were up-regulated and 104 down-regulated. Twenty of these genes encode proteins that are related to the immune response (cytokines, chemokines, their receptors, cytokine/chemokines-related genes, transcription and signal transduction genes) and are discussed in more detail. Our data indicate that exposure to DNCB does not induce a typical maturation pattern in DCs. PMID:16125363

Schoeters, E; Verheyen, G R; Van Den Heuvel, R; Nelissen, I; Witters, H; Van Tendeloo, V F I; Schoeters, G E R; Berneman, Z N

2005-10-01

217

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

218

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

Code of Federal Regulations, 2014 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...

2014-07-01

219

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

Code of Federal Regulations, 2013 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...

2013-07-01

220

Chemical composition and larvicidal activity of edible plant-derived essential oils against the pyrethroid-susceptible and -resistant strains of Aedes aegypti (Diptera: Culicidae).  

PubMed

The chemical compositions and larvicidal potential against mosquito vectors of selected essential oils obtained from five edible plants were investigated in this study. Using a GC/MS, 24, 17, 20, 21, and 12 compounds were determined from essential oils of Citrus hystrix, Citrus reticulata, Zingiber zerumbet, Kaempferia galanga, and Syzygium aromaticum, respectively. The principal constituents found in peel oil of C. hystrix were beta-pinene (22.54%) and d-limonene (22.03%), followed by terpinene-4-ol (17.37%). Compounds in C. reticulata peel oil consisted mostly of d-limonene (62.39%) and gamma-terpinene (14.06%). The oils obtained from Z. zerumbet rhizome had alpha-humulene (31.93%) and zerumbone (31.67%) as major components. The most abundant compounds in K. galanga rhizome oil were 2-propeonic acid (35.54%), pentadecane (26.08%), and ethyl-p-methoxycinnamate (25.96%). The main component of S. aromaticum bud oil was eugenol (77.37%), with minor amounts of trans-caryophyllene (13.66%). Assessment of larvicidal efficacy demonstrated that all essential oils were toxic against both pyrethroid-susceptible and resistant Ae. aegypti laboratory strains at LC50, LC95, and LC99 levels. In conclusion, we have documented the promising larvicidal potential of essential oils from edible herbs, which could be considered as a potentially alternative source for developing novel larvicides to be used in controlling vectors of mosquito-borne disease. PMID:20618656

Sutthanont, Nataya; Choochote, Wej; Tuetun, Benjawan; Junkum, Anuluck; Jitpakdi, Atchariya; Chaithong, Udom; Riyong, Doungrat; Pitasawat, Benjawan

2010-06-01

221

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

222

Assessment and Applications of NASA Ozone Data Products Derived from Aura OMI-MLS Satellite Measurements in Context of the GMI Chemical Transport Model  

NASA Technical Reports Server (NTRS)

Measurements from the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS), both onboard the Aura spacecraft, have been used to produce daily global maps of column and profile ozone since August 2004. Here we compare and evaluate three strategies to obtain daily maps of tropospheric and stratospheric ozone from OMI and MLS measurements: trajectory mapping, direct profile retrieval, and data assimilation. Evaluation is based upon an assessment that includes validation using ozonesondes and comparisons with the Global Modeling Initiative (GMI) chemical transport model (CTM). We investigate applications of the three ozone data products from near-decadal and inter-annual timescales to day-to-day case studies. Zonally averaged inter-annual changes in tropospheric ozone from all of the products in any latitude range are of the order 1-2 Dobson Units while changes (increases) over the 8-year Aura record investigated http://eospso.gsfc.nasa.gov/atbd-category/49 vary approximately 2-4 Dobson Units. It is demonstrated that all of the ozone products can measure and monitor exceptional tropospheric ozone events including major forest fire and pollution transport events. Stratospheric ozone during the Aura record has several anomalous inter-annual events including stratospheric warming split events in the Northern Hemisphere extra-tropics that are well captured using the data assimilation ozone profile product. Data assimilation with continuous daily global coverage and vertical ozone profile information is the best of the three strategies at generating a global tropospheric and stratospheric ozone product for science applications.

Ziemke, J. R.; Olsen, M. A.; Witte, J. C.; Douglass, A. R.; Strahan, S. E.; Wargan, K.; Liu, X.; Schoeberl, M. R.; Yang, K.; Kaplan, T. B.; Pawson, S.; Duncan, B. N.; Newman, P. A.; Bhartia, K.; Heney, M. K.

2013-01-01

223

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

224

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

PubMed

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

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

2014-11-01

225

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

226

Biotechnology and derived products  

Technology Transfer Automated Retrieval System (TEKTRAN)

Microorganisms able to infect and kill insect pests, metabolites from plants and microorganisms, and transgenic crops are biotechnologically derived products that are being promoted for use to control insect pests in lieu of chemical insecticides. Products based on these technologies effectively co...

227

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

PubMed

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

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

2014-04-01

228

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

PubMed

Glioblastoma multiforme (GBM) is one of the most common brain malignancies and has a very poor prognosis. Recent evidence suggests that the presence of cancer stem cells (CSC) in GBM and the rare CSC subpopulation that is resistant to chemotherapy may be responsible for the treatment failure and unfavorable prognosis of GBM. A garlic-derived compound, Z-ajoene, has shown a range of biological activities, including anti-proliferative effects on several cancers. Here, we demonstrated for the first time that Z-ajoene specifically inhibits the growth of the GBM CSC population. CSC sphere-forming inhibition was achieved at a concentration that did not exhibit a cytotoxic effect in regular cell culture conditions. The specificity of this inhibitory effect on the CSC population was confirmed by detecting CSC cell surface marker CD133 expression and biochemical marker ALDH activity. In addition, stem cell-related mRNA profiling and real-time PCR revealed the differential expression of CSC-specific genes, including Notch, Wnt, and Hedgehog, upon treatment with Z-ajoene. A proteomic approach, i.e., reverse-phase protein array (RPPA) and Western blot analysis, showed decreased SMAD4, p-AKT, 14.3.3 and FOXO3A expression. The protein interaction map (http://string-db.org/) of the identified molecules suggested that the AKT, ERK/p38 and TGF? signaling pathways are key mediators of Z-ajoene's action, which affects the transcriptional network that includes FOXO3A. These biological and bioinformatic analyses collectively demonstrate that Z-ajoene is a potential candidate for the treatment of GBM by specifically targeting GBM CSCs. We also show how this systemic approach strengthens the identification of new therapeutic agents that target CSCs. PMID:25078449

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

2014-07-01

229

Systemic Approaches Identify a Garlic-Derived Chemical, Z-ajoene, as a Glioblastoma Multiforme Cancer Stem Cell-Specific Targeting Agent  

PubMed Central

Glioblastoma multiforme (GBM) is one of the most common brain malignancies and has a very poor prognosis. Recent evidence suggests that the presence of cancer stem cells (CSC) in GBM and the rare CSC subpopulation that is resistant to chemotherapy may be responsible for the treatment failure and unfavorable prognosis of GBM. A garlic-derived compound, Z-ajoene, has shown a range of biological activities, including anti-proliferative effects on several cancers. Here, we demonstrated for the first time that Z-ajoene specifically inhibits the growth of the GBM CSC population. CSC sphere-forming inhibition was achieved at a concentration that did not exhibit a cytotoxic effect in regular cell culture conditions. The specificity of this inhibitory effect on the CSC population was confirmed by detecting CSC cell surface marker CD133 expression and biochemical marker ALDH activity. In addition, stem cell-related mRNA profiling and real-time PCR revealed the differential expression of CSC-specific genes, including Notch, Wnt, and Hedgehog, upon treatment with Z-ajoene. A proteomic approach, i.e., reverse-phase protein array (RPPA) and Western blot analysis, showed decreased SMAD4, p-AKT, 14.3.3 and FOXO3A expression. The protein interaction map (http://string-db.org/) of the identified molecules suggested that the AKT, ERK/p38 and TGF? signaling pathways are key mediators of Z–ajoene’s action, which affects the transcriptional network that includes FOXO3A. These biological and bioinformatic analyses collectively demonstrate that Z-ajoene is a potential candidate for the treatment of GBM by specifically targeting GBM CSCs. We also show how this systemic approach strengthens the identification of new therapeutic agents that target CSCs. PMID:25078449

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

2014-01-01

230

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

231

Growth model and the effect of CuO nanocrystallites on the properties of chemically derived epitaxial thin films of YBa2Cu3O7-x  

NASA Astrophysics Data System (ADS)

In metalorganic deposition using trifluoroacetates (TFA-MOD), CuO nanocrystallites in calcined film, which influence the critical current density (Jc) of the resulting film, have seldom been considered before. CuO nanocrystallites ripen and grow during the calcining process at 200-250 degC and grow into large CuO grains in the YBa2Cu3O7-x (YBCO) film. The final diameter of the grains is about 0.1 mum. When highly purified coating solution is used, suppressing the creation of nanocrystallites in the precursor film is an effective way to obtain high-Jc YBCO film because the nanocrystallites consist only of CuO. We obtained the highest-Jc YBCO film on LaAlO3 single crystal with a calcining process of 9h43m at 200-250 degC. It was 141 nm thick and had a Jc of 7.5 MA/cm2 (77 K, 0 T), as measured by the four-probe method. The firing process of TFA-MOD still has several unsolved problems; why can H2O and HF gas diffuse quickly within the film? These phenomena can be explained by a model with a quasiliquid consisting of Y, Ba, Cu, O, H, and F. The H2O and HF can move quickly in the quasiliquid network within the film during the firing process. According to the model, we can get more conversion of CuO nanocrystallites into quasiliquid by increasing the amount of water vapor. Jc of the film was increased from 3.3 to 4.5 MA/cm2 (77 K, 0 T) by increasing the humidity from 4.2% to 12.1% during the long calcining profile of 66h40m at 200-250 degC. These results confirm the above model. CuO nanocrystallites in precursor films induce nonstoichiometric metal contents in the quasiliquid. Isolated CuO grains in YBCO film indirectly cause nonstoichiometric quasiliquid in other areas. Such nonstoichiometric quasiliquid leads to non-YBCO materials such as BaO, Y2O3, and Y2Cu2O5. Thus, films derived from non-highly purified coating solution and ones prepared with an inappropriate calcining process both have lower Jc values. Micrographs obtained by transmission electron microscopy and Jc results support this hypothesis.

Araki, Takeshi; Niwa, Toshiharu; Yamada, Yutaka; Hirabayashi, Izumi; Shibata, Junko; Ikuhara, Yuichi; Kato, Kazumi; Kato, Takeharu; Hirayama, Tsukasa

2002-09-01

232

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

2014-04-01

233

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. PMID:24686557

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

2014-01-01

234

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

235

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Salt of polyalkylenepolyamine derivative (generic...Specific Chemical Substances § 721.10328 Salt of polyalkylenepolyamine derivative (generic...chemical substance identified generically as salt of polyalkylenepolyamine...

2013-07-01

236

Radical-assisted chemical doping for chemically derived graphene  

PubMed Central

Carrier doping of graphene is one of the most challenging issues that needs to be solved to enable its use in various applications. We developed a carrier doping method using radical-assisted conjugated organic molecules in the liquid phase and demonstrated all-wet fabrication process of doped graphene films without any vacuum process. Charge transfer interaction between graphene and dopant molecules was directly investigated by spectroscopic studies. The resistivity of the doped graphene films was drastically decreased by two orders of magnitude. The resistivity was improved by not only carrier doping but the improvement in adhesion of doped graphene flakes. First-principles calculation supported the model of our doping mechanism. PMID:24355062

2013-01-01

237

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

238

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 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)...

2011-07-01

239

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 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)...

2014-07-01

240

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 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)...

2012-07-01

241

40 CFR 721.1760 - Substituted benzotriazole derivatives.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

242

40 CFR 721.646 - Aminofluoran derivative (generic name).  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

243

40 CFR 721.9740 - Brominated triazine derivative.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Brominated triazine derivative. 721.9740 Section 721.9740... § 721.9740 Brominated triazine derivative. (a) Chemical substance and significant...generically as a brominated triazine derivative (PMN P-91-403) is subject...

2010-07-01

244

40 CFR 721.10172 - Alkylamide derivative (generic).  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

245

40 CFR 721.9079 - Dihydro quinacridone derivative (generic).  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

246

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

247

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

248

Phthalates TEACH Chemical Summary  

E-print Network

This TEACH Chemical Summary is a compilation of information derived primarily from U.S. EPA and ATSDR resources, and the TEACH Database. The TEACH Database contains summaries of research studies pertaining to developmental exposure and/or health effects for each chemical or chemical group. TEACH does not perform any evaluation of the validity or quality of these research studies. Research studies that are specific for adults are not included in the TEACH Database, and typically are not described in the TEACH Chemical Summary. I.

U. S. Epa; Exposure Assessment

249

Chemical Mechanical Planarization- Chemical  

NSDL National Science Digital Library

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

2012-12-07

250

Chemical Threats  

MedlinePLUS

... indicate a chemical agent release. Before Before a Chemical Threat What you should do to prepare for ... and on the highest level. During During a Chemical Threat What you should do in a chemical ...

251

Chemical Emergencies  

MedlinePLUS

When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

252

LLNL Chemical Kinetics Modeling Group  

SciTech Connect

The LLNL chemical kinetics modeling group has been responsible for much progress in the development of chemical kinetic models for practical fuels. The group began its work in the early 1970s, developing chemical kinetic models for methane, ethane, ethanol and halogenated inhibitors. Most recently, it has been developing chemical kinetic models for large n-alkanes, cycloalkanes, hexenes, and large methyl esters. These component models are needed to represent gasoline, diesel, jet, and oil-sand-derived fuels.

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

2008-09-24

253

Complex derivatives  

NASA Astrophysics Data System (ADS)

The intrinsic complexity of the financial derivatives market has emerged as both an incentive to engage in it, and a key source of its inherent instability. Regulators now faced with the challenge of taming this beast may find inspiration in the budding science of complex systems.

Battiston, Stefano; Caldarelli, Guido; Georg, Co-Pierre; May, Robert; Stiglitz, Joseph

2013-03-01

254

Chemical Equations  

NSDL National Science Digital Library

It discusses the process of equation writing and balancing chemical equations in perspective of the chemical changes that take place during a reaction. This module is the third in a series on chemical reactions.

Carpi, Anthony

2003-03-27

255

Chemical Microsensors For Detection Of Explosives And Chemical Warfare Agents  

DOEpatents

An article of manufacture is provided including a substrate having an oxide surface layer and a layer of a cyclodextrin derivative chemically bonded to said substrate, said layer of a cyclodextrin derivative adapted for the inclusion of selected compounds, e.g., nitro-containing organic compounds, therewith. Such an article can be a chemical microsensor capable of detecting a resultant mass change from inclusion of the nitro-containing organic compound.

Yang, Xiaoguang (Los Alamos, NM); Swanson, Basil I. (Los Alamos, NM)

2001-11-13

256

New poly(ester urea) derived from l-leucine: Electrospun scaffolds loaded with antibacterial drugs and enzymes.  

PubMed

Electrospun scaffolds from an amino acid containing poly(ester urea) (PEU) were developed as promising materials in the biomedical field and specifically in tissue engineering applications. The selected poly(ester urea) was obtained with a high yield and molecular weight by reaction of phosgene with a bis(?-aminoacyl)-?,?-diol-diester monomer. The polymer having l-leucine, 1,6-hexanediol and carbonic acid units had a semicrystalline character and relatively high glass transition and melting temperatures. Furthermore it was highly soluble in most organic solvents, an interesting feature that facilitated the electrospinning process and the effective incorporation of drugs with bactericidal activity (e.g. biguanide derivatives such as clorhexidine and polyhexamethylenebiguanide) and enzymes (e.g. ?-chymotrypsin) that accelerated the degradation process. Continuous micro/nanofibers were obtained under a wide range of processing conditions, being diameters of electrospun fibers dependent on the drug and solvent used. Poly(ester urea) samples were degradable in media containing lipases and proteinases but the degradation rate was highly dependent on the surface area, being specifically greater for scaffolds with respect to films. The high hydrophobicity of new scaffolds had repercussions on enzymatic degradability since different weight loss rates were found depending on how samples were exposed to the medium (e.g. forced or non-forced immersion). New scaffolds were biocompatible, as demonstrated by adhesion and proliferation assays performed with fibroblast and epithelial cells. PMID:25492010

Díaz, Angélica; Del Valle, Luis J; Tugushi, David; Katsarava, Ramaz; Puiggalí, Jordi

2015-01-01

257

Chemical Communication  

NSDL National Science Digital Library

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

0000-00-00

258

Auto-oxidative coupling of glycine derivatives.  

PubMed

The unprecedented title reaction between glycine derivatives and indoles, as well as the auto-oxidative Povarov/aromatization tandem reaction of glycine derivatives with olefins are described. The reactions were performed in the absence of redox-active catalysts and chemical oxidants under mild reaction conditions. Only simple organic solvents and air (or O2 ) were required. PMID:25288283

Huo, Congde; Yuan, Yong; Wu, Mingxia; Jia, Xiaodong; Wang, Xicun; Chen, Fengjuan; Tang, Jing

2014-12-01

259

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

260

Chemical burns  

PubMed Central

Objectives To report a burn unit’s experience with chemical burns and to discuss the fundamental principles in managing chemical burns. Design A chart review. Setting A burn centre at a major university-affiliated hospital. Patients Twenty-four patients with chemical burns, representing 2.6% of all burn admissions over an 8-year period at the Ross Tilley Regional Adult Burn Centre. Seventy-five percent of the burn injuries were work-related accidents. Chemicals involved included hydrofluoric acid, sulfuric acid, black liquor, various lyes, potassium permanganate and phenol. Results Fourteen patients required excision and skin grafting. Complications were frequent and included ocular chemical contacts, wound infections, tendon exposures, toe amputation and systemic reactions from absorption of chemical. One patient died from a chemical scald burn to 98% of the body surface area. Conclusions The key principles in the management of chemical burns include removal of the chemical, copious irrigation, limited use of antidotes, correct estimation of the extent of injury, identification of systemic toxicity, treatment of ocular contacts and management of chemical inhalation injury. Individualized treatment is emphasized. PMID:8640619

Cartotto, Robert C.; Peters, Walter J.; Neligan, Peter C.; Douglas, Leith G.; Beeston, Jeff

1996-01-01

261

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

Microsoft Academic Search

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

Vasiliki Valla

2007-01-01

262

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

Code of Federal Regulations, 2012 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....

2012-07-01

263

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

Code of Federal Regulations, 2011 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....

2011-07-01

264

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

265

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

Code of Federal Regulations, 2014 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....

2014-07-01

266

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

267

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

268

The studies of tautomerism in 6-mercaptopurine derivatives by 1H- 13C, 1H- 15N NMR and 13C, 15N CPMAS-experimental and quantum chemical approach  

NASA Astrophysics Data System (ADS)

Tautomerism in 6-mercaptopurine (6mpH), 2,6-dimercaptopurine (2,6dmp) and 6-mercaptopurine-9-riboside (6mp-9rb) was studied in the solution with 2D NMR methods- 1H- 13C HMBC and 1H- 15N HMQC. The 15N NMR signals were assigned and the distribution of mobile protons proposed on the basis of ?13C, ?15N chemical shifts and JHC, JHN coupling constants, determined with HECADE. These heterocycles appear in DMSO- d6 as the thionic species with predominance of the following tautomers: N(1)H, N(7)H for 6mpH; N(1)H, N(3)H, N(7)H for 2,6dmp; N(1)H for 6mp-9rb. Quantum-chemical NMR calculations by GIAO method(RHF/6-31G**//B3LYP/6-31G**) allowed to evaluate the ratios of N(7)H, N(9): N(7), N(9)H tautomeric forms as ca. 3:1 for 6mpH and nearly 10:0 for 2,6dmp. The 13C and 15N CPMAS spectra were measured for solid 6mpH·H 2O, anhydrous 6mpH, 2,6dmp and 6-mercaptopurinium chloride (6mpH 2Cl), confirming the thionic character of all compounds. The 15N chemical shifts in the solid phase were calculated (B3LYP/6-31G**) for 6mpH·H 2O and 6mpH 2Cl, basing on the re-determined single crystal X-ray data (optimised with RHF/3-21G**).

Pazderski, Leszek; ?akomska, Iwona; Wojtczak, Andrzej; Sz?yk, Edward; Sitkowski, Jerzy; Kozerski, Lech; Kamie?ski, Bohdan; Ko?mi?ski, Wiktor; Tousek, Jaromír; Marek, Radek

2006-03-01

269

CHEMICAL ENGINEERING AND MANUFACTURING CHEMICAL ENGINEERING  

E-print Network

CHEMICAL ENGINEERING AND MANUFACTURING CHEMICAL ENGINEERING Objective Chemical Engineers of chemicals. This lesson introduces students to one component of chemical engineering: food processing, and a chemical engineer 2. How chemical engineers are involved in food production 3. That chemical engineers need

Provancher, William

270

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)

271

Chemical sensors  

DOEpatents

Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising (a) a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, operatively coupled to (b) a transducer capable of directly converting said expansion or contraction to a measurable electrical response.

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

1991-01-01

272

Chemical sensors  

DOEpatents

Sensors responsive to small changes in the concentration of chemical species are disclosed. The sensors comprise a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment. They are operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical response. 9 figures.

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

1991-07-02

273

Chemical geodynamics  

Microsoft Academic Search

Consideration is given to the following three principal boundary conditions relating to the nature and development of chemical structure in the earth's mantle: (1) inferred scale lengths for mantle chemical heterogeneities, (2) interrelationships of the various isotopic tracers, and (3) the bulk composition of the earth. These boundary conditions are integrated with geophysical constraints in order to evaluate models for

A. Zindler; S. R. Hart

1986-01-01

274

Chemical Reactions  

NSDL National Science Digital Library

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

National Science Teachers Association (NSTA)

2009-05-01

275

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

276

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

277

Protein Chemical Shift Prediction  

E-print Network

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

Larsen, Anders S

2014-01-01

278

Chemical lasers  

NASA Astrophysics Data System (ADS)

Fundamental properties of chemical lasers are presented and principal systems described in the nonclassified literature are reviewed. The fundamentals of the production of inversion in molecular gases by chemical processes are discussed. Iodine, HF, and DF lasers are described. The chemical reaction in the pulsed chemical HF and DF lasers is introduced by a transverse electrical discharge. In spite of the high dissociation energy and the electronegative properties which are unfavorable for a stable discharge regime, SF6 is used as fluorine source for safety reasons. The pulse energies reach 26 J in agreement with estimated values. The advantage of the present system is that is can also operate as CO2 laser in the TEA mode. The radiation of DF lasers is particularly interesting for military near-Earth applications because of its good transmission properties in the atmosphere.

Hugenschmidt, M.; Wey, J.

1985-05-01

279

Chemical Peeling  

MedlinePLUS

... the skin heals can cause unwanted side effects ranging from infection to scarring. If you have any ... Tanzi EL and Alster TS. “Skin Resurfacing: Ablative Lasers, Chemical Peels, and Dermabrasion.” In: Wolff K, Goldsmith ...

280

Chemical Emergency  

MedlinePLUS

... can be recycled, which is better for our environment. If you have questions about how to dispose of a chemical, call the facility or the environmental or recycling agency to learn the proper method of disposal. ...

281

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

282

Chemical sensors  

DOEpatents

Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising a mechanicochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, either operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical or optical response, or adhered to a second inert polymeric strip, or doped with a conductive material. 12 figs.

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

1992-06-09

283

Chemical sensors  

DOEpatents

Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising a mechanicochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, either operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical or optical response, or adhered to a second inert polymeric strip, or doped with a conductive material.

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

1992-01-01

284

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

285

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

286

Higher order fractional derivatives  

E-print Network

Based on the Liouville-Weyl definition of the fractional derivative, a new direct fractional generalization of higher order derivatives is presented. It is shown, that the Riesz and Feller derivatives are special cases of this approach.

Richard Herrmann

2009-06-12

287

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

288

Validation study of a method for assaying DE-310, a macromolecular carrier conjugate containing an anti-tumor camptothecin derivative, and the free drug in tumor tissue by high performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry.  

PubMed

DE-310 is a macromolecular carrier conjugate containing an anti-tumor camptothecin derivative, DX-8951, which is conjugated to a water-soluble polymer via a peptide spacer. Assay methods have been developed for the determination of a polymer-bonded DX-8951 conjugate, DX-8951, and Glycyl-DX-8951 concentrations in murine Meth A tumor tissue. Free DX-8951 and Glycyl-DX-8951 were extracted from tumor tissue homogenates by protein precipitation and analyzed by LC/MS/MS (method I). Conjugated DX-8951 was isolated by solid-phase extraction after digestion with a thermolysin. The productive phenylalanyl-glycyl-DX-8951 was analyzed by LC/MS/MS (method II). The lower limits of quantitation of DX-8951, Glycyl-DX-8951, and conjugated DX-8951 were 1.36, 1.34 and 73.7 ng/g (as DX-8951 equivalent). These two methods showed satisfactory sensitivity, precision and accuracy. To study the pharmacokinetics of DE-310, it would be of great help to assay the polymer-bonded DX-8951 and its released drugs in tumor tissue. PMID:15484225

Oguma, Toshihiro; Morikawa, Hiroshi; Iwasaki, Daisuke; Atsumi, Ryo

2005-01-01

289

The biguanide metformin alters phosphoproteomic profiling in mouse brain.  

PubMed

Metformin, a potent antihyperglycemic agent is recommended as the first-line oral therapy for type 2 diabetes (T2D). Recently, metformin has been reported to be beneficial to neurodegenerative disease models. However, the putative mechanisms underlying the neuroprotective effects of metformin in disease models are unknown. Thus, we applied LC-MS/MS-based pattern analysis and two-dimensional electrophoresis (2DE)-based proteomic approach to understand the global phosphoproteomic alteration in the brain of metformin-administrated mice. Collectively, LC-MS/MS-based pattern analysis reveals that 41 phosphoproteins were upregulated and 22 phosphoproteins were downregulated in the brain of metformin-administrated mice. In addition, 5 differentially expressed phosphoproteins were identified upon metformin administration by 2DE coupled with mass spectrometry. The phosphorylation status of metabolic enzymes was decreased while that of mitochondrial proteins was increased by metformin. Interestingly, phosphorylated ?-synuclein was significantly decreased by metformin administration. Taken together, our results might provide potential pathways to understand the pharmacological effect of metformin on neuroprotection. PMID:25067825

Khang, Rin; Park, ChiHu; Shin, Joo-Ho

2014-09-01

290

Use of biguanides to improve response to chemotherapy.  

PubMed

Metformin is a commonly utilized antidiabetic agent, which has been associated with improved clinical outcomes in cancer patients. The precise mechanism of action remains unclear, but preclinical evidence suggests that metformin can sensitize tumor cells to the effects to conventional chemotherapeutic agents and ionizing radiation (IR). In this chapter we discuss the general background of an approach to evaluate the effects of metformin on conventional chemotherapeutic agent toxicity in a preclinical model. PMID:24839014

Sandulache, Vlad C; Yang, Liangpeng; Skinner, Heath D

2014-01-01

291

Chemical defense by termite soldiers  

Microsoft Academic Search

The chemistry of the defensive secretions of termite soldiers is reviewed. The structural variety of the chemical weapons, the uses of these substances in defense, and some potential biosynthetic interrelationships are discussed. Classification of the monoterpenes, sesquiterpenes, diterpenes, and various acetate-derived compounds according to termite subfamilies places the known defense substances in a phylogenetic perspective.

Glenn D. Prestwich

1979-01-01

292

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.

293

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

294

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 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...

2013-07-01

295

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

296

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

297

Biofuels and bio-products derived from  

E-print Network

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

Ginzel, Matthew

298

40 CFR 721.1825 - Bisphenol A, epichloro-hy-drin, polyalkylenepolyol and poly-iso-cyanato derivative.  

Code of Federal Regulations, 2010 CFR

...polyalkylenepolyol and poly-iso-cyanato derivative. 721.1825 Section 721.1825...polyalkylenepolyol and poly-iso-cyanato derivative. (a) Chemical substance and significant...polyalkylenepolyol and polyisocyanato derivative (PMN P-89-750) is subject...

2010-07-01

299

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

300

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

301

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 ...

302

Terpenoids and gamma-pyrone derivatives from Prangos tschimganica.  

PubMed

The methanol extract of the dried aerial parts of Prangos tschimganica afforded seven monoterpenoids and four gamma-pyrone derivatives. Their structures were established on the basis of chemical and spectroscopic evidence. PMID:11336255

Shikishima, Y; Takaishi, Y; Honda, G; Ito, M; Takeda, Y; Kodzhimatov, O K; Ashurmetov, O

2001-05-01

303

Absolute Time Derivatives  

E-print Network

A four dimensional treatment of nonrelativistic space-time gives a natural frame to deal with objective time derivatives. In this framework some well known objective time derivatives of continuum mechanics appear as Lie-derivatives. Their coordinatized forms depends on the tensorial properties of the relevant physical quantities. We calculate the particular forms of objective time derivatives for scalars, vectors, covectors and different second order tensors from the point of view of a rotating observer. The relation of substantial, material and objective time derivatives is treated.

T. Matolcsi; P. Van

2006-08-31

304

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.

305

40 CFR 454.60 - Applicability; description of manufacture of rosin-based derivatives subcategory.  

Code of Federal Regulations, 2013 CFR

...Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) GUM AND WOOD CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Rosin-Based Derivatives Subcategory § 454.60...

2013-07-01

306

40 CFR 454.60 - Applicability; description of manufacture of rosin-based derivatives subcategory.  

Code of Federal Regulations, 2014 CFR

...Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) GUM AND WOOD CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Rosin-Based Derivatives Subcategory § 454.60...

2014-07-01

307

40 CFR 454.60 - Applicability; description of manufacture of rosin-based derivatives subcategory.  

Code of Federal Regulations, 2012 CFR

...Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) GUM AND WOOD CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Rosin-Based Derivatives Subcategory § 454.60...

2012-07-01

308

Trypanocidal nitroimidazole derivatives: relationships among chemical structure and genotoxic activity.  

PubMed

Human American trypanosomiasis is resurgent in Latin Americans, and new drugs are urgently required as current medications suffer from a number of drawbacks. Some nitroheterocycles have been demonstrated to exert a potent activity against trypanosomes. However, host toxicity issues halted their development as trypanocides. As part of the efforts to develop new compounds in order to treat parasitic infections, it is important to define their structure-activity relationship. In this study, 5-nitromegazol and two of its analogues, 4-nitromegazol, and 1-methyl-5-nitro-2-imidazolecarboxaldehyde 5-nitroimidazole-thiosemicarbazone, were tested and compared for in vitro induction of DNA damage in human leukocytes by the comet assay, performed at different pHs to better identify the types of damage. Specific oxidatively generated damage to DNA was also measured by using the comet assay with endonucleases. DNA damage was found in 5-nitromegazol-treated cells: oxidative stress appeared as the main source of DNA damage. 4-Nitromegazol did not produce any significant effect, thus confirming that 4-nitroimidazoles isomers have no important biological activity. The 5-nitroimidazole-thiosemicarbazone induced DNA damage with a higher efficiency than 5-nitromegazol. The central role in the reduction process played by the acidic hydrazine proton present in the thiosemicarbazone group but not in the cyclic (thiadiazole) form can contribute to rationalise our results. Given its versatility, thiosemicarbazone moiety could be involved in different reactions with nitrogenous bases (nucleophilic and/or electrophilic attacks). PMID:17291457

Buschini, Annamaria; Giordani, Federica; de Albuquerque, Cristina Northfleet; Pellacani, Claudia; Pelosi, Giorgio; Rossi, Carlo; Zucchi, Tânia Maria Araújo Domingues; Poli, Paola

2007-05-15

309

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. PMID:24674343

2014-01-01

310

Chemical composition of the Orion nebula derived from echelle spectrophotometry  

Microsoft Academic Search

We present echelle spectroscopy in the 3500- to 7060-Å range for two positions of the Orion nebula. The data were obtained using the 2.1-m telescope at Observatorio Astrónmico Nacional in San Pedro Mártir, Baja California. We have measured the intensities of about 220 emission lines, in particular 81 permitted lines of C+, N+, N++, 0°, 0+, Ne0, Si+, Si++ and

C. Esteban; M. Peimbert; S. Torres-Peimbert; V. Escalante

1998-01-01

311

Physical and chemical characterization of waste wood derived biochars  

Technology Transfer Automated Retrieval System (TEKTRAN)

Biochar, a solid byproduct generated during waste biomass pyrolysis or gasification in the absence (or near-absence) of oxygen, has recently garnered interest for both agricultural and environmental management purposes owing to its unique physicochemical properties, such as its high surface area and...

312

Pyrazine-Derived Disulfide-Reducing Agent for Chemical Biology  

PubMed Central

For fifty years, dithiothreitol (DTT) has been the preferred reagent for the reduction of disulfide bonds in proteins and other biomolecules. Herein we report on the synthesis and characterization of 2,3-bis(mercaptomethyl)pyrazine (BMMP), a readily accessible disulfide-reducing agent with reactivity under biological conditions that is markedly superior to DTT and other known reagents. PMID:25014913

Lukesh, John C.; Wallin, Kelly K.

2014-01-01

313

Chemicals from corn: much more than ethanol  

SciTech Connect

A leading U.S. chemical company, A.E. Staley, Decatur, Ill., came onstream towards the end of 1981 with a pilot plant designed to produce methyl glucoside by fermentation from corn starch about half the cost of using conventional synthesis from hydrocarbons. The company aims ultimately to produce a line of corn-derived organic chemicals. Another company, CPC International, N.J., is selling corn raw materials - corn starch, corn syrup, dextrose - to chemical companies and then working with them to produce specific organic chemicals.

Not Available

1982-02-24

314

21 CFR 189.120 - Cobaltous salts and its derivatives.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 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 ,...

2014-04-01

315

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

316

21 CFR 189.120 - Cobaltous salts and its derivatives.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 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 ,...

2013-04-01

317

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

318

21 CFR 189.120 - Cobaltous salts and its derivatives.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 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 ,...

2010-04-01

319

Chemical constituents of the lichen, Candelaria concolor: A complete NMR and chemical degradative investigation  

Microsoft Academic Search

A detailed chemical and spectroscopic investigation of the terrestrial lichen Candelaria concolor has yielded several lichenic metabolites belonging to the pulvinic acid series, as well as several depside derivatives including pulvinic dilactone (1), vulpinic acid (4) and calycin (5). The chemical transformation of 1 to pulvinic acid (3) is reported for the first time, as is the conversion of atranorin

Daniel A. Dias; Sylvia Urban

2009-01-01

320

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

321

Nature's chemicals and synthetic chemicals: Comparative toxicology  

Microsoft Academic Search

The toxicology of synthetic chemicals is compared to that of natural chemicals, which represent the vast bulk of the chemicals to which humans are exposed. It is argued that animals have a broad array of inducible general defenses to combat the changing array of toxic chemicals in plant food (nature's pesticides) and that these defenses are effective against both natural

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

1990-01-01

322

Chemical Accelerators The phrase "chemical accelerators"  

E-print Network

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

Zare, Richard N.

323

Chemical information science coverage in Chemical Abstracts.  

PubMed

For many years Chemical Abstracts has included in its coverage publications on chemical documentation or chemical information science. Although the bulk of those publications can be found in section 20 of Chemical Abstracts, many relevant articles were found scattered among 39 other sections of CA in 1984-1985. In addition to the scattering of references in CA, the comprehensiveness of Chemical Abstracts as a secondary source for chemical information science is called into question. Data are provided on the journals that contributed the most references on chemical information science and on the languages of publication of relevant articles. PMID:3558505

Wiggins, G

1987-02-01

324

The Dangers of Derivatives.  

ERIC Educational Resources Information Center

Heavy investment in derivatives, whose value derives from the price movement of some underlying security, has meant heavy losses for some colleges and universities despite the fact that institutional investors are required to assure that they understand the risks of such investment. (MSE)

Blumenstyk, Goldie

1994-01-01

325

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.

2004-11-11

326

Renewable Chemicals: Dehydroxylation of Glycerol and Polyols  

PubMed Central

The production of renewable chemicals is gaining attention over the past few years. The natural resources from which they can be derived in a sustainable way are most abundant in sugars, cellulose and hemicellulose. These highly functionalized molecules need to be de-functionalized in order to be feedstocks for the chemical industry. A fundamentally different approach to chemistry thus becomes necessary, since the traditionally employed oil-based chemicals normally lack functionality. This new chemical toolbox needs to be designed to guarantee the demands of future generations at a reasonable price. The surplus of functionality in sugars and glycerol consists of alcohol groups. To yield suitable renewable chemicals these natural products need to be defunctionalized by means of dehydroxylation. Here we review the possible approaches and evaluate them from a fundamental chemical aspect. PMID:21887771

ten Dam, Jeroen; Hanefeld, Ulf

2011-01-01

327

[Chemical food contaminants].  

PubMed

Chemical food contaminants are substances which are neither present naturally in the usual raw material used for food production nor are added during the regular production process. Examples are environmental pollutants or contaminants derived from agricultural production of crops or livestock or from inadequate manufacturing of the food product itself. More difficult is the classification of those compounds formed during regular manufacturing such as products of thermal processes including flavoring substances. In these cases, it is common practice to call those compounds contaminants which are known for their adverse effects such as acrylamide, whereas constituents which add to the food-specific flavor such as Maillard products formed during roasting, baking etc. are not termed contaminants. From a toxicological viewpoint this distinction is not always clear-cut. Important groups of chemical contaminants are metals such as mercury or lead, persistent organic pollutants such as polychlorinated biphenyls and related pollutants, which are regularly found in certain types of food originating from background levels of these compounds in our environment. Furthermore, natural toxins form microorganisms or plants, and compounds formed during thermal treatment of food are of major interest. In general, a scientific risk assessment has to be carried out for any known contaminant. This comprises an exposure analysis and a toxicological and epidemiological assessment. On these grounds, regulatory and/or technological measures can often improve the situation. Major conditions for a scientific risk assessment and a successful implementation of regulations are highly developed food quality control, food toxicology and nutritional epidemiology. PMID:15378171

Schrenk, D

2004-09-01

328

Chemical Homogeneity in Collinder 261 and Implications for Chemical Tagging  

E-print Network

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

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

2006-11-28

329

The Partial Derivative Machine  

NSDL National Science Digital Library

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

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

2014-01-31

330

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

331

Chemical evolution models for NGC 6822 using planetary nebulae abundances  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

332

Derivative Matching Game  

NSDL National Science Digital Library

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

2009-05-29

333

Derivative Matching Game  

NSDL National Science Digital Library

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

334

Credit derivatives in Brazil  

E-print Network

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

Rüther, Henrique

2007-01-01

335

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

336

Microfluidic chemical reaction circuits  

DOEpatents

New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

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

2012-06-26

337

Chemical and Biomolecular Engineering  

E-print Network

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

Pennycook, Steve

338

PREDICTION OF OCTANOL/WATER PARTITION COEFFICIENT (KOW) WITH ALGORITHMICALLY DERIVED VARIABLES  

EPA Science Inventory

A statistical model was developed with algorithmically derived independent variables based on chemical structure for prediction of octanol/water partition coefficients (Kow) measured for more than 4,000 chemicals. he procedure first classified the chemicals into 14 groups based o...

339

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

Microsoft Academic Search

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

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

2000-01-01

340

Performance characteristics of endoreversible chemical engines  

NASA Astrophysics Data System (ADS)

Chemical engines process mass flows to convert differences in chemical potential into work—the analog of heat engines processing heat flows to generate work from temperature differences. For isothermal endoreversible chemical engines constrained to finite-time operation—examples of which include mass exchangers, electrochemical, photochemical, and solid-state devices: (i) optimal cycle types for maximizing average power output, (ii) upper bounds on power production, and (iii) sensitivity of these results to mass-transfer law, illustrated for linear and diffusive behavior, are derived.

Gordon, J. M.; Orlov, Vladimir N.

1993-11-01

341

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. PMID:2217211

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

1990-01-01

342

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. PMID:23734336

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

2013-01-01

343

Derivatives of tetrodecamycin.  

PubMed

The derivatives of tetrodecamycin (1), being introduced acyl, carbamoyl and alkyl groups at 14-hydroxyl group and modified at exo-methylene group, were synthesized and evaluated on their antibacterial activities. Although 14-O-substituted tetrodecamycins (3 approximately 19) showed weak activity against Pasteurella piscicida, they were more active against Gram-positive bacteria than 1. Among them, 15 showed approximately 10-fold higher activity than 1. The derivatives (20 approximately 23) modified at 4 or 5 positions had moderate antibacterial activity. The absolute structure of 4(R),5-dibromotetrodecamycin (23) was determined by X-ray crystallographic analysis. PMID:8557576

Tsuchida, T; Iinuma, H; Nakamura, K T; Nakamura, H; Sawa, T; Hamada, M; Takeuchi, T

1995-11-01

344

Relationship between Legionella pneumophila and Acanthamoeba polyphaga: Physiological status and susceptibility to chemical inactivation  

Microsoft Academic Search

Survival studies were conducted on Legionella pneumophila cells that had been grown intracellulary in Acanthamoeba polyphaga and then exposed to polyhexamethylene biguanide (PHMB), benzisothiazolone (BIT), and 5-chloro-N-methylisothiazolone (CMIT). Susceptibilities were also determined for L. pneumophila grown under iron-sufficient and iron-depleted conditions. BIT was relatively ineffective against cells to PHMB and CMIT. The activities of all three biocides were greatly reduced

J. Barker; I. Farrell; M. R. W. Brown; P. J. Collier; P. Gilbert

1992-01-01

345

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

346

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

Code of Federal Regulations, 2010 CFR

...Benzene, (2-bromoethyl)-, ar-bromo derivatives. 721.1240 Section 721.1240...Benzene, (2-bromoethyl)-, ar-bromo derivatives. (a) Chemical substance and significant...benzene, (2-bromoethyl)-, ar-bromo derivatives (PMN P-84-704; CAS No....

2010-07-01

347

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

Code of Federal Regulations, 2010 CFR

...false Benzene, ethenyl-, ar-bromo derivatives. 721.1230 Section 721.1230...1230 Benzene, ethenyl-, ar-bromo derivatives. (a) Chemical substance and significant...identified as benzene, ethenyl-, ar-bromo derivatives (PMN P-84-660; CAS...

2010-07-01

348

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

349

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

350

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

351

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

Code of Federal Regulations, 2013 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...

2013-07-01

352

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

Code of Federal Regulations, 2014 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...

2014-07-01

353

Telomeric 30 Overhangs Derive  

E-print Network

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

de Lange, Titia

354

Treatment of biomass to obtain a target chemical  

DOEpatents

Target chemicals were produced using biocatalysts that are able to ferment sugars derived from treated biomass. Sugars were obtained by pretreating biomass under conditions of high solids and low ammonia concentration, followed by saccharification.

Dunson, Jr., James B. (Newark, DE); Tucker, III, Melvin P. (Lakewood, CO); Elander, Richard T. (Evergreen, CO); Hennessey, Susan Marie (Avondale, PA)

2010-08-24

355

December 2010 ORDERING CHEMICALS  

E-print Network

December 2010 ORDERING CHEMICALS Order your chemicals through SunRISE. This is the fastest, most accurate method to order chemicals, and SunRISE offers University Stockroom for ordering solvents to obtain the best price. If a chemical is not in Sun

Rhoads, James

356

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

E-print Network

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

Rohs, Remo

357

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

E-print Network

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

Rohs, Remo

358

Chemically defined generation of human cardiomyocytes.  

PubMed

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

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

2014-08-01

359

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

360

Synthesis and biological activity of Citridone A and its derivatives.  

PubMed

Citridone A (1), originally isolated as a potentiator of antifungal miconazole activity from a fungal culture broth, has a phenyl-R-furopyridone structure. Because of its unique ring structure, 11 derivatives were chemically synthesized and their biological activity was evaluated. Derivatives 17, 20 and 21 potentiated miconazole activity against Candida albicans. Furthermore, 1, 14, 20 and 21 were found to inhibit yellow pigment production in methicillin-resistant Staphylococcus aureus. PMID:24643052

Fukuda, Takashi; Shimoyama, Kenta; Nagamitsu, Tohru; Tomoda, Hiroshi

2014-06-01

361

Fractional Derivative Cosmology  

E-print Network

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

Mark D. Roberts

2009-09-07

362

Insulin-derived amyloidosis  

PubMed Central

Amyloidosis is the term for diseases caused by the extracellular deposition of insoluble polymeric protein fibrils in tissues and organs. Insulin-derived amyloidosis is a rare, yet significant complication of insulin therapy. Insulin-derived amyloidosis at injection site can cause poor glycemic control and increased insulin dose requirements because of the impairment in insulin absorption, which reverse on change of injection site and/or excision of the mass. This entity should be considered and assessed by histopathology and immunohistochemistry, in patients with firm/hard local site reactions, which do not regress after cessation of insulin injection at the affected site. Search strategy: PubMed was searched with terms “insulin amyloidosis”. Full text of articles available in English was reviewed. Relevant cross references were also reviewed. Last search was made on October 15, 2014.

Gupta, Yashdeep; Singla, Gaurav; Singla, Rajiv

2015-01-01

363

Platform Chemicals from an Oilseed Biorefinery  

SciTech Connect

The US chemical industry is $460 billion in size where a $150 billion segment of which is non-oxygenated chemicals that is sourced today via petroleum but is addressable by a renewable feedstock if one considers a more chemically reduced feedstock such as vegetable oils. Vegetable oil, due to its chemical functionality, provides a largely untapped opportunity as a renewable chemical source to replace petroleum-derived chemicals and produce platform chemicals unavailable today. This project examined the fertile intersection between the rich building blocks provided by vegetable oils and the enhanced chemical modification capability provided by metathesis chemistry. The technology advanced in this study is the process of ethylene cross-metathesis (referred to as ethenolysis) with vegetable oil and vegetable oil derivatives to manufacture the platform-chemical 9-decenoic acid (or 9DA) and olefin co-products. The project team meet its goals of demonstrating improved catalyst efficiencies of several multiples, deepening the mechanistic understanding of metathesis, synthesis and screening of dozens of new catalysts, designing and modeling commercial processes, and estimating production costs. One demonstrable result of the study was a step change improvement in catalyst turnover number in the ethenolysis of methyl oleate as reported here. We met our key measurable of producing 100 lbs of 9DA at the pilot-scale, which demonstrated ability to scale-up ethenolysis. DOE Project funding had significant positive impact on development of metathetically modified vegetable oils more broadly as the Cargill/Materia partnership, that was able to initiate primarily due to DOE funding, has succeeded in commercializing products, validating metathesis as a platform technology, and expanding a diverse products portfolio in high value and in large volume markets. Opportunities have expanded and business development has gained considerable momentum and enabled further expansion of the Materia/Cargill relationship. This project exceeded expectations and is having immediate impact on DOE success by replacing petroleum products with renewables in a large volume application today.

Tupy, Mike; Schrodi Yann

2006-11-06

364

[Synthesis of porphyrin derivatives].  

PubMed

This paper presents the preparation of eleven 2, 4 or 6, 7-substituted porphyrine derivatives II-XII from I or diethyl ether of IV. The effects of these compounds, with irradiation, on DNA synthesis in L1210 cells were studied. The results showed that (1) all of these compounds were effective while (2) Va or Vb, VI and VII were more effective. PMID:1839589

Lu, Y H; Liu, F C

1991-01-01

365

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

366

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

367

Chemically Regulated Expression Systems and their Applications in Transgenic Plants  

Microsoft Academic Search

In the past 20 years, several systems have been developed to control transgene expression in plants using chemicals. The components used to construct these systems are derived from regulatory sequences mostly from non-plant organisms such as bacteria, fungi, insects and mammals. These constructs allowed transgene expression to be controlled temporally, spatially and quantitatively with the help of exogenous chemicals, without

Renhou Wang; Xiaofu Zhou; Xingzhi Wang

2003-01-01

368

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

369

Synthesis and cytotoxicity study of alkannin derivatives.  

PubMed

Alkannin derivatives (3-19) were prepared through the reaction of beta,beta-dimethylacrylalkannin (1), the most abundant isohexenylnaphthazarin isolated from the roots of Arnebia euchroma, with different types of nucleophiles such as amines and thiols in the absence or presence of a reducing agent. The cytotoxicities of 1-8, 10-14 and 19 against four human carcinoma cell line (GLC-82, CNE2, Bel-7402, K-562) were found to be markedly higher than that of the naturally occurring beta,beta-dimethylacrylalkannin (1) and acetylalkannin (2). This study also shed light on the understanding of the biological activities in terms of the chemical reactivity of alkannins. PMID:15337288

Huang, Zhi-Shu; Wu, Hai-Qiang; Duan, Zhi-Fang; Xie, Bing-Fen; Liu, Zong-Chao; Feng, Gong-Kan; Gu, Lian-Quan; Chan, Albert S C; Li, Yue-Ming

2004-09-01

370

Bacterial degradation of chlorophenols and their derivatives  

PubMed Central

Chlorophenols (CPs) and their derivatives are persistent environmental pollutants which are used in the manufacture of dyes, drugs, pesticides and other industrial products. CPs, which include monochlorophenols, polychlorophenols, chloronitrophenols, chloroaminophenols and chloromethylphenols, are highly toxic to living beings due to their carcinogenic, mutagenic and cytotoxic properties. Several physico-chemical and biological methods have been used for removal of CPs from the environment. Bacterial degradation has been considered a cost-effective and eco-friendly method of removing CPs from the environment. Several bacteria that use CPs as their sole carbon and energy sources have been isolated and characterized. Additionally, the metabolic pathways for degradation of CPs have been studied in bacteria and the genes and enzymes involved in the degradation of various CPs have been identified and characterized. This review describes the biochemical and genetic basis of the degradation of CPs and their derivatives. PMID:24589366

2014-01-01

371

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

372

Synthesis of tetrahydrobenzimidazole derivatives  

Microsoft Academic Search

O! l| 3,5,5-Trimethyl- 7-ketotetrahydro benzimidazole (III) was similarly obtained from 5,5-dimethylcycl ohexane-l,2,3-tri one monophenylhydraz one. Treatment of the sodium derivative of III with bromoacetophenone and then with ammonium acetate in acetic acid gave the previously unknown 2,8,8-trimethyl- 5-phenyl7,8-dihydro-9H-p yrazino [3,2,1-h,i]benzimidazole (IV), which was isolated as the picrate. H3C\\\\ ~.~ tlaC CH 3

V. I. Shvedov; L. B. Altukhova; A. N. Grinev

1972-01-01

373

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

374

Capacitive chemical sensor  

DOEpatents

A microfabricated capacitive chemical sensor can be used as an autonomous chemical sensor or as an analyte-sensitive chemical preconcentrator in a larger microanalytical system. The capacitive chemical sensor detects changes in sensing film dielectric properties, such as the dielectric constant, conductivity, or dimensionality. These changes result from the interaction of a target analyte with the sensing film. This capability provides a low-power, self-heating chemical sensor suitable for remote and unattended sensing applications. The capacitive chemical sensor also enables a smart, analyte-sensitive chemical preconcentrator. After sorption of the sample by the sensing film, the film can be rapidly heated to release the sample for further analysis. Therefore, the capacitive chemical sensor can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

Manginell, Ronald P; Moorman, Matthew W; Wheeler, David R

2014-05-27

375

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...

376

Chemical Emergencies Overview  

MedlinePLUS

... Agents Toxic Alcohols Vesicants Chemical-Specific Fact Sheets Toxicology FAQs Case Definitions Toxic Syndrome Descriptions Toxicological Profiles ... and chemical-specific fact sheets and in the toxicology FAQs on this Web site. In-depth information ...

377

Advanced chemical lasers  

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

378

Chemical Reactions (Netorials)  

NSDL National Science Digital Library

Chemical Reactions: this is a resource in the collection "Netorials". The Netorials cover selected topics in first-year chemistry including: Chemical Reactions, Stoichiometry, Thermodynamics, Intermolecular Forces, Acids & Bases, Biomolecules, and Electrochemistry.

379

Tobacco and chemicals (image)  

MedlinePLUS

Some of the chemicals associated with tobacco smoke include ammonia, carbon dioxide, carbon monoxide, propane, methane, acetone, hydrogen cyanide and various carcinogens. Other chemicals that are associated with chewing ...

380

Household Chemical Emergencies  

MedlinePLUS

... the risk of injury. Before Before a Household Chemical Emergency The following are guidelines for buying and ... is (800) 222-1222. During During a Household Chemical Emergency Get out of the residence immediately if ...

381

DTP - Chemical Biology Consortium  

Cancer.gov

Chemical Biology Consortium Home Discovery Development Pathways Grants/Contracts Books/Publications Site Search Data Search What's New Chemical Biology Consortium (CBC) Division of Cancer Treatment and Diagnosis To download Adobe Reader for documents

382

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

383

Chemical of the Week  

NSDL National Science Digital Library

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

Shakhashiri, Bassam Z.

1997-01-01

384

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

385

HARVARD UNIVERSITY CHEMICAL BIOLOGY  

E-print Network

HARVARD UNIVERSITY CHEMICAL BIOLOGY PHD PROGRAM 2013-2014 Student Handbook #12;Program Contacts at the beginning of each semester. Laboratory Rotations Students in the Chemical Biology Program are expected an interest in having Chemical Biology Program Students in their labs. Students may rotate in the labs

Church, George M.

386

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

387

More on Chemical Changes  

NSDL National Science Digital Library

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

388

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...

389

CHEMICAL SAFETY Emergency Numbers  

E-print Network

- 1 - CHEMICAL SAFETY MANUAL 2010 #12;- 2 - Emergency Numbers UNBC Prince George Campus Security Prince George Campus Chemstores 6472 Chemical Safety 6472 Radiation Safety 5530 Biological Safety 5530 use, storage, handling, waste and emergency management of chemicals on the University of Northern

Bolch, Tobias

390

Chemical Domino Demonstration  

Microsoft Academic Search

The Chemical Domino Demonstration is both educational and entertaining. It provides an excellent means for a review of chemical concepts at the conclusion of a general chemistry course. This demonstration consists of a number of different chemical reactions occurring in sequence in a Rube Goldberg-type apparatus. These reactions include the reduction of water by an active metal, the oxidation of

M. Dale Alexander

1998-01-01

391

Biological and Chemical Security  

Microsoft Academic Search

The LLNL Chemical & Biological National Security Program (CBNP) provides science, technology and integrated systems for chemical and biological security. Our approach is to develop and field advanced strategies that dramatically improve the nation's capabilities to prevent, prepare for, detect, and respond to terrorist use of chemical or biological weapons. Recent events show the importance of civilian defense against terrorism.

Fitch

2002-01-01

392

Chemical mapping of planetary surfaces  

NASA Technical Reports Server (NTRS)

Two instruments, the gamma-ray spectrometer and the X-ray fluorescence spectrometer, are uniquely suited to the chemical mapping of planetary surfaces from orbit. Through their detection of characteristic line spectra they measure the concentrations of a suite of elements in each area overflown. Multielement chemical maps derived from these remote measurements are used in the construction of evolutionary models of planetary bodies and of the solar system as a whole. The NaI(T1) gamma-ray spectrometer and a gas proportional X-ray spectrometer were flown over 20 percent of the lunar surface during the Apollo 15 and 16 missions. These instruments measured chemical differences across the boundaries of known lunar provinces and revealed several new features of lunar-surface composition. Advanced spectrometers which are under development for future missions are able to educe much more information in a given time span than the Apollo instruments. They may be used in possible future missions such as Lunar Polar Orbiter, a Mars orbiter, a Mercury orbiter, outer planet satellite missions, rendezvous with asteroids and cometary nuclei, and surface-penetrating planetary probes.

Haines, E. L.; Metzger, A. E.; Arnold, J. R.

1976-01-01

393

Pharmacology of endothelium-derived nitric oxide and nitrovasodilators.  

PubMed Central

Nitric oxide is the active chemical species responsible for the vasodilator action of nitroglycerin, nitroprusside, and related nitrovasodilators. The most potent vasodilator and inhibitor of platelet aggregation known, nitric oxide was recently discovered to occur endogenously as the endothelium-derived relaxing factor. The pharmacology of endothelium-derived nitric oxide is virtually identical to that of the clinically used nitrovasodilators. Although endothelium-derived relaxing factor or endothelium-derived nitric oxide seems to be important in animals, its significance in humans still needs to be shown. We review the recent discoveries in the identification, biosynthesis, metabolism, and biologic actions of endothelium-derived nitric oxide, its significance in humans, and its relation to the clinically used nitrovasodilators. PMID:1902612

Ignarro, L. J.; Ross, G.; Tillisch, J.

1991-01-01

394

Acquiring Knowledge of Derived Nominals and Derived Adjectives in Context  

ERIC Educational Resources Information Center

Purpose: This research investigated children's ability to acquire semantic and syntactic knowledge of derived nominals and derived adjectives in the context of short passages. The study also investigated the relation of morphological awareness and the ability to acquire knowledge of derived words in context. Method: A total of 106 children in…

Marinellie, Sally A.; Kneile, Lynn A.

2012-01-01

395

Antistaphylococcal activity of novel salicylanilide derivatives.  

PubMed

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

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

2012-03-01

396

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

397

Chemical synthesis of proteins.  

PubMed

Proteins have become accessible targets for chemical synthesis. The basic strategy is to use native chemical ligation, Staudinger ligation, or other orthogonal chemical reactions to couple synthetic peptides. The ligation reactions are compatible with a variety of solvents and proceed in solution or on a solid support. Chemical synthesis enables a level of control on protein composition that greatly exceeds that attainable with ribosome-mediated biosynthesis. Accordingly, the chemical synthesis of proteins is providing previously unattainable insight into the structure and function of proteins. PMID:15869385

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

2005-01-01

398

Chemical Synthesis of Proteins  

PubMed Central

Proteins have become accessible targets for chemical synthesis. The basic strategy is to use native chemical ligation, Staudinger ligation, or other orthogonal chemical reactions to couple synthetic peptides. The ligation reactions are compatible with a variety of solvents and proceed in solution or on a solid support. Chemical synthesis enables a level of control on protein composition that greatly exceeds that attainable with ribosome-mediated biosynthesis. Accordingly, the chemical synthesis of proteins is providing previously unattainable insight into the structure and function of proteins. PMID:15869385

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

2010-01-01

399

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

400

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

401

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

402

Efficieny handling effluent gases through chemical scrubbing  

NASA Astrophysics Data System (ADS)

This paper is presented as an information source for efficiencies of chemical scrubbing. In it, we will discuss the specific problems of scrubbing silane, disilane, diborane, phosphine, hydrogen selenide and arsine. We will explain the scrubber dynamics, gases and flow rates used along with liquid mediums. The equipment and procedures used for testing, as well as the determination of the results, will be discussed. We intend to give examples of possible reactions and documentation of our efficiencies. Installation and maintenance will be touched, as well as our experiments into accidental catastrophic releases. From all of this we will derive conclusions as to the best possible means of wet chemical scrubbing.

Herman, Tim; Soden, Scott

1988-07-01

403

Chemical Hygiene Plan i January 2013 Chemical Hygiene Plan  

E-print Network

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

Nizkorodov, Sergey

404

40 CFR 454.60 - Applicability; description of manufacture of rosin-based derivatives subcategory.  

Code of Federal Regulations, 2011 CFR

...Section 454.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GUM AND WOOD CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Rosin-Based Derivatives Subcategory § 454.60...

2011-07-01

405

Derivatives of molecular electromagnetic properties using nonlocal susceptibility densities  

NASA Astrophysics Data System (ADS)

This thesis presents three analytic derivative relationships. The underlying concept of these three relationships is connecting the change of a molecular property to other well-defined molecular properties. The foundation of this work lies in nonlocal polarizability density theory. The nonlocal polarizability density characterizes the polarization at one point in a molecule due to its reaction with an electric field at another point in the molecule. In the first part, the derivative of the electronic hyperpolarizability with respect to a Cartesian nuclear coordinate is related to the nonlocal second hyperpolarizability density, the nuclear charge and the dipole propagator. The derivation uses the derivatives of the wavefunctions and operators that comprise the six- term hyperpolarizability. These derivatives, which are also derived, are substituted into the hyperpolarizability to yield a sixty-term expression. The initial result is manipulated algebraically in a nontrivial way to yield the equality. A brief review of hyper-Raman scattering theory is given. Recent applications of hyper-Raman scattering are considered. In the second part a new expression for the derivative of the polarization propagator with respect to an arbitrary coordinate is derived in terms of the quadratic polarization propagator and a sum of polarization propagators. The derivation involves calculating the derivative of a creation and annihilation operator pair with respect to an arbitrary parameter. Then the propagator derivative is calculated via the derivatives of many-electron wavefunctions. Past work calculating the derivatives of molecular properties using polarization propagator techniques is briefly reviewed. The third part concerns finding an expression for the derivative of the electronic magnetic moment with respect to nuclear momentum and its relationship to a nonlocal magnetizability density. The magnetizability density has a structure similar to the chemical shift. The relationship is found by considering the magnetic field produced by a moving nucleus as a perturbation on the electronic structure. The ground state wavefunctions are corrected to first order in perturbation theory using the nuclear magnetic field as the perturbation. The corrected wavefunctions are used to calculate the expectation value of the magnetic moment. When the derivative of this expectation value is taken with respect to nuclear momentum, its relationship with the nonlocal chemical shift density is uncovered. The result is correct when adiabatic wavefunctions that go beyond the Born- Oppenheimer approximation are used. The physical content of the equation is interpreted as a description of intramolecular magnetic response. Other possible paths to a complete susceptibility theory are considered. One path involves substitution of 4- currents into the definition of the nonlocal polarizability density. Other paths arise from an initial consideration of the relativistic Dirac equation and subsequent analysis using the Gordon decomposition and the Foldy-Wouthuysen transformation.

Tisko, Edmund Leo

406

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

407

A Generic QSAR for Assessing the Bioaccumulation Potential of Organic Chemicals in Aquatic Food Webs  

E-print Network

A Generic QSAR for Assessing the Bioaccumulation Potential of Organic Chemicals in Aquatic Food the bioaccumulation potential of organic chemicals in aquatic food webs. The QSAR is derived by parameterization quality. The QSAR provides estimates of the bioaccumulation potential of organic chemicals in higher

Gobas, Frank

408

TECHNICAL BASIS FOR NARCOTIC CHEMICALS AND POLYCYCLIC AROMATIC HYDROCARBON CRITERIA. II. MIXTURES AND SEDIMENTS  

Microsoft Academic Search

A method is presented for developing sediment quality guidelines (SQG) for narcotic chemicals in general and polycyclic aromatic hydrocarbons (PAHs) in particular. The guidelines can be applied to any individual or mixture of narcotic chemicals including PAHs using only the chemical's octanol\\/water partition coefficient. They are derived using the final chronic values for type I narcotics developed from a database

Dominic M. Di Toro; Joy A. McGrath

2000-01-01

409

Highly Hazardous Chemicals and Chemical Spills EPA Compliance Fact Sheet  

E-print Network

Highly Hazardous Chemicals and Chemical Spills EPA Compliance Fact Sheet Vanderbilt Environmental.safety.vanderbilt.edu HIGHLY HAZARDOUS CHEMICAL WASTES Certain chemical wastes must be handled by special procedures due to their highly hazardous nature. These chemicals include expired isopropyl and ethyl ethers (these chemicals

Wikswo, John

410

Chemical evolution STRUCTURE OF GALAXIES  

E-print Network

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

Kruit, Piet van der

411

Process development of specialty chemicals.  

E-print Network

??The chemical processing industries have shifted their attention from commodity chemicals to high-value-added specialty chemicals in recent decades. Specialty chemicals always serve as major ingredients… (more)

Fung, Ka Yip

2006-01-01

412

Radioactively labelled porphyrin derivatives  

NASA Astrophysics Data System (ADS)

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

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

2003-01-01

413

Vaccine-derived polioviruses.  

PubMed

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

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

2014-11-01

414

Excimer laser chemical problems  

SciTech Connect

Techniques need to be developed to maintain XeF and XeCl laser performance over long periods of time without degradation resulting from chemical processes occurring within the laser. The dominant chemical issues include optical damage, corrosions of laser materials, gas contamination, and control of halogen concentration. Each of these issues are discussed and summarized. The methods of minimizing or controlling the chemical processes involved are presented.

Tennant, R.; Peterson, N.

1982-01-01

415

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

416

Insect Chemical Warfare  

NSDL National Science Digital Library

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

0002-11-30

417

Alternative fuels and chemicals from synthesis gas  

SciTech Connect

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

Unknown

1998-08-01

418

ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS  

SciTech Connect

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

Unknown

1999-01-01

419

Alternative Fuels and Chemicals From Synthesis Gas  

SciTech Connect

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

none

1998-07-01

420

ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS  

SciTech Connect

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

Unknown

1998-01-01

421

Field emission chemical sensor  

DOEpatents

A field emission chemical sensor for specific detection of a chemical entity in a sample includes a closed chamber enclosing two field emission electrode sets, each field emission electrode set comprising (a) an electron emitter electrode from which field emission electrons can be emitted when an effective voltage is connected to the electrode set; and (b) a collector electrode which will capture said electrons emitted from said emitter electrode. One of the electrode sets is passive to the chemical entity and the other is active thereto and has an active emitter electrode which will bind the chemical entity when contacted therewith.

Panitz, J.A.

1983-11-22

422

Apparatus for chemical synthesis  

DOEpatents

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

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

2011-05-10

423

Chemical Processing Manual  

NASA Technical Reports Server (NTRS)

Chemical processes presented in this document include cleaning, pickling, surface finishes, chemical milling, plating, dry film lubricants, and polishing. All types of chemical processes applicable to aluminum, for example, are to be found in the aluminum alloy section. There is a separate section for each category of metallic alloy plus a section for non-metals, such as plastics. The refractories, super-alloys and titanium, are prime candidates for the space shuttle, therefore, the chemical processes applicable to these alloys are contained in individual sections of this manual.

Beyerle, F. J.

1972-01-01

424

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

425

40 CFR 721.1225 - Benzene, 1,2-dimethyl-, poly-propene derivatives, sulfonated, po-tas-sium salts.  

Code of Federal Regulations, 2010 CFR

...derivatives, sulfonated, po-tas-sium salts. 721.1225 Section 721.1225 Protection...derivatives, sulfonated, po-tas-sium salts. (a) Chemical substances and significant...polypropene derivatives, sulfonated, potassium salts (PMN P-89-711) is subject to...

2010-07-01

426

40 CFR 721.1225 - Benzene, 1,2-dimethyl-, poly-propene derivatives, sulfonated, po-tas-sium salts.  

Code of Federal Regulations, 2012 CFR

...derivatives, sulfonated, po-tas-sium salts. 721.1225 Section 721.1225 Protection...derivatives, sulfonated, po-tas-sium salts. (a) Chemical substances and significant...polypropene derivatives, sulfonated, potassium salts (PMN P-89-711) is subject to...

2012-07-01

427

40 CFR 721.1225 - Benzene, 1,2-dimethyl-, poly-propene derivatives, sulfonated, po-tas-sium salts.  

Code of Federal Regulations, 2014 CFR

...derivatives, sulfonated, po-tas-sium salts. 721.1225 Section 721.1225 Protection...derivatives, sulfonated, po-tas-sium salts. (a) Chemical substances and significant...polypropene derivatives, sulfonated, potassium salts (PMN P-89-711) is subject to...

2014-07-01

428

Chemically prepared lead magnesium niobate dielectrics  

SciTech Connect

A chemical solution powder synthesis technique has been developed that produces first, 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. Chem-prep PMN dielectrics with peak dielectric constants greater than 22,000 and polarizations in excess of 29 {micro}C/cm{sup 2} were obtained for 1,100 C firing treatments. Substantial decreases in dielectric constant and polarization were measured for chemically prepared PMN ceramics fired at lower temperatures, consistent with previous work on mixed oxide materials.

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

1998-11-01

429

Separations Needs for the Alternate Chemical Cycles  

SciTech Connect

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

Frederick F. Stewart

2007-05-01

430

Recent advances in chemically amplified resist materials  

SciTech Connect

The design of resists based on the principle of chemical amplification has provided imaging materials with remarkable sensitivity. These materials all function on the basis of photo-generation of a latent image of catalyst. In a subsequent step that is usually thermally activated, the catalyst acts on some part of the formulation to modify the solubility of the film. In most cases reported to date, the systems depend on acid that is generated by the irradiation of neutral compounds which produce acidic radiolysis products. Acid catalysis of side chain cleavage, cross-linking, and hydrolysis are but a few of the reactions that have been exploited in the design of acid catalyzed, chemically amplified resists. This paper now reports the authors` work on the use of photo-generated base in the design of resists that derive high sensitivity from base catalyzed chemical transformations. A variety of base catalyzed reactions have been auditioned for this application.

Willson, C.G.; MacDonald, S.A.; Niesert, C.P. [IBM Almaden Research Center, San Jose, CA (United States); Frechet, J.M.J.; Leung, M.K.; Ackerman, A. [Cornell Univ., Ithaca, NY (United States)

1993-12-31

431

CHEMICAL CATEGORIES IN EPA'S NEW CHEMICALS PROGRAM  

EPA Science Inventory

Under section 5 of the Toxic Substances Control Act (TSCA),any person who intends to manufacture or import a new chemical substance, or mixture containing such a substance, in the United States for commercial purposes must submit a premanufacture notice (PMN) to the Environmental...

432

Marine-Derived Angiogenesis Inhibitors for Cancer Therapy  

PubMed Central

Angiogenesis inhibitors have been successfully used for cancer therapy in the clinic. Many marine-derived natural products and their analogues have been reported to show antiangiogenic activities. Compared with the drugs in the clinic, these agents display interesting characteristics, including diverse sources, unique chemical structures, special modes of action, and distinct activity and toxicity profiles. This review will first provide an overview of the current marine-derived angiogenesis inhibitors based on their primary targets and/or mechanisms of action. Then, the marine-derived antiangiogenic protein kinase inhibitors will be focused on. And finally, the clinical trials of the marine-derived antiangiogenic agents will be discussed, with special emphasis on their application potentials, problems and possible coping strategies in their future development as anticancer drugs. PMID:23502698

Wang, Ying-Qing; Miao, Ze-Hong

2013-01-01

433

Chitooligosaccharide and Its Derivatives: Preparation and Biological Applications  

PubMed Central

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

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

2014-01-01

434

Deriving bedform phase diagrams  

NSDL National Science Digital Library

Students prepare for this activity by working with a unidirectional flume with a sand bed. We adjust water depth, flow velocity, and channel slope to achieve a range of bed states, in an effort for them to understand the controls on bedforms. This portion of the activity could be done in lecture or via another exercise that makes use of digital video of actual experiments. The activity itself is a jigsaw: students form groups of three, each group responsible for plotting depth vs. velocity plots of bedform state for a single sand grain size range (0.10-0.14 mm, 0.5-0.64 mm, and 1.3-1.8 mm). These data are provided to them as Excel files and the data were directly 'stolen' from the original depth vs. velocity plots in Middleton and Southard (1984), Mechanics of Sediment Movement, SEPM Short Course Number 3. Datathief software (available free on the web) was used to steal the data. The data are arranged in columns: depth, velocity, and bedform type. Students must plot each of the different bedform types with a different symbol, then they have to define field boundaries. It is critical that they have never seen the original plots in their textbook. The goal is for them to derive them on their own, not to regurgitate what is in their textbook or elsewhere. After they complete their plots for each grain size range, the groups re-arrange themselves into groups of three with one representative from each of the grain size groups. They then must try to evaluate the effects of changing grain size on bedform state. Finally, after completing the exercise, the bedform analysis is linked to the cross stratification that is produced under conditions of high sediment fallout rates and the given bed state. The activity gives students practice working with realistic datasets, exposure to the role of physical modeling in sedimentary geology, and a chance to plot and interpret real data. Furthermore, it really solidifies the link between cross stratification and its dynamic interpretation from the rock record.

Tom Hickson

435

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

Microsoft Academic Search

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

Yong Liu; Chuxia Lin; Yonggui Wu

2007-01-01

436

A Unique Chemoenzymatic Synthesis of r-Galactosyl Epitope Derivatives Containing Free Amino Groups: Efficient Separation  

E-print Network

A Unique Chemoenzymatic Synthesis of r-Galactosyl Epitope Derivatives Containing Free Amino Groups-(1f3)- -Gal-(1f4)- -Glc-N3 (15). Compounds 2 and 15 are derivatives of natural R-Gal epitopes. Both of the cell surface antigenic determinants (epitopes).2 The chemical synthesis of oligosaccharides containing

Chen, Xi

437

Derivation of the Second Law of Thermodynamics from Boltzmann's Distribution Law.  

ERIC Educational Resources Information Center

Shows how the thermodynamic condition for equilibrium in an isolated system can be derived by the application of Boltzmann's law to a simple physical system. States that this derivation could be included in an introductory course on chemical equilibrium to help prepare students for a statistical mechanical treatment presented in the curriculum.…

Nelson, P. G.

1988-01-01

438

Great Lakes: Chemical Monitoring  

ERIC Educational Resources Information Center

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

Delfino, Joseph J.

1976-01-01

439

Elemental Chemical Puzzlers  

ERIC Educational Resources Information Center

This paper provides nine short chemically based puzzles or problems extensible for use with students from middle school to college. Some of these will strengthen students' recognition of individual elements and element names. Others require students to focus on the salient properties of given chemical elements.

Thomas, Nicholas C.

2009-01-01

440

Chemicals and Allied Products.  

ERIC Educational Resources Information Center

Presents a literature review of wastes from chemical industry, covering publications of 1976-77. This review covers: (1) wastewater treatment by-product type; (2) biological, and physical/chemical treatments; and (3) source treatment. A list of 80 references is also presented. (HM)

Nelson, R. F.; Hovious, J. C.

1978-01-01

441

Chemical Process Synthesis.  

ERIC Educational Resources Information Center

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

Siirola, J. J.

1982-01-01

442

Recognizing Chemical Hazards Module  

NSDL National Science Digital Library

The Center for the Advancement of Process Technology presents this free sample module on recognizing chemical hazards. It focuses on chemical hazards specific to process industries, and their impact on safety, health and the environment. The material also introduces the purpose and components of an MSDS.

2013-01-09

443

Chemical Compositions of Stars  

NASA Astrophysics Data System (ADS)

In 1835, in a famously inaccurate forecast, the French philosopher Auguste Comte wrote of stars that, `We understand the possibility of determining their shapes, their distances, their sizes and their movements; whereas we would never know how to study by any means their chemical composition…'. At the close of the 20th century the accurate measurement of the abundances of the chemical elements in...

Leckrone, D.; Murdin, P.

2000-11-01

444

Chemical and Physical Changes  

NSDL National Science Digital Library

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

445

Chemical Reactions and Stoichiometry  

NSDL National Science Digital Library

In this activity, students explore reactions in which chemical bonds are formed and broken. Students experiment with changing the temperature and the concentration of the atoms in order to see how these affect reaction rates. They also learn how to communicate what happens during a chemical reaction by writing the ratios of reactants and products, known as stoichiometry.

The Concord Consortium

2011-12-11

446

Chemical Kinetics: Isolation Method  

NSDL National Science Digital Library

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

Blauch, David N.

447

Microorganisms and Chemical Pollution  

ERIC Educational Resources Information Center

Discusses the importance of microorganisms in chemical pollution and pollution abatement. Selected chemical pollutants are chosen to illustrate that microorganisms synthesize hazardous substances from reasonably innocuous precursors, while others act as excellent environmental decontaminating agents by removing undesirable natural and synthetic…

Alexander, M.

1973-01-01

448

Difficult Decisions: Chemical Warfare.  

ERIC Educational Resources Information Center

Gives the background history and chemistry of modern day chemical warfare from World War I to the present. Provides discussion questions to stimulate deeper thinking on the issue. Contains a discussion activity called "Can New Chemical Weapons Lead to Humane Warfare?" (CW)

Slesnick, Irwin L.; Miller, John A.

1988-01-01

449

Chemical warfare agents  

Microsoft Academic Search

There is an increased risk that civilian populations will be targets of domestic terrorism. Release of chemical warfare agents in these populations can cause a large number of casualties, with children being disproportionately affected. Chemical agents pose a significant risk to unprepared medical providers. Emergency medical personnel must be able to diagnose and manage victims of toxic exposures. This article

Rohit Shenoi

2002-01-01

450

CHITOSAN DERIVATIVES FOR TISSUE ENGINEERING.  

E-print Network

??Chitosan, a naturally occurring polysaccharide, and its derivatives have been widely explored for biomedical applications due to their biocompatibility and biodegradability. In our studies, we… (more)

Qiu, Yongzhi

2008-01-01

451

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

PubMed Central

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

2014-01-01

452

Limits and Derivatives: The Derivative as a Function  

NSDL National Science Digital Library

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

Freeze, Michael

2003-01-22

453

Cellulose Derivatives Derived From Pulp and Paper Mill Sludge  

Microsoft Academic Search

Cellulose derivatives were produced from the cellulose fraction of pulp and paper mill sludge. The raw primary sludge was reacted under conventional cellulose derivatization conditions and the modified cellulose was isolated, in most cases, by dissolution in a suitable solvent. The cellulose derivatives produced were cellulose nitrate, cellulose acetate, carboxymethylcellulose, hydroxyethylcellulose, and methylcellulose. These compounds were characterized by Fourier transform

David G. Barkalow; Raymond A. Young

1985-01-01

454

Alternative algebras admitting derivations with invertible values and invertible derivations  

NASA Astrophysics Data System (ADS)

We prove an analogue of the Bergen-Herstein-Lanski theorem for alternative algebras: describe all alternative algebras that admit derivations with invertible values. We also prove an analogue of Moens' theorem for alternative algebras (a finite-dimensional alternative algebra over a field of characteristic zero is nilpotent if and only if it admits an invertible Leibniz derivation).

Kaygorodov, I. B.; Popov, Yu S.

2014-10-01

455

Holographic recording materials development. [using stilbene, indigo, and thioindigo derivatives  

NASA Technical Reports Server (NTRS)

The area of organic cis-trans photoisomerization systems for holographic memory applications was examined. Photochemical studies were made of stilbene, indigo, and thioindigo derivatives in solution and in a variety of polymer matrix materials, to optimize the photorefractive behavior of the chemical system as a whole. Lithium niobate was used to study the writing and reading efficiencies of thick phase holograms. Both phase-wave holograms and Fourier-transform holograms were employed, and a number of reconstruction techniques are discussed. The possibility of using cis-trans photoisomerization of appropriate organic chemicals as the basis for a holographic recording system is confirmed.

1975-01-01

456

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

NASA Astrophysics Data System (ADS)

The chemical Fokker-Planck equation and the corresponding chemical Langevin equation are commonly used approximations of the chemical master equation. These equations are derived from an uncontrolled, second-order truncation of the Kramers-Moyal expansion of the chemical master equation and hence their accuracy remains to be clarified. We use the system-size expansion to show that chemical Fokker-Planck estimates of the mean concentrations and of the variance of the concentration fluctuations about the mean are accurate to order ?-3/2 for reaction systems which do not obey detailed balance and at least accurate to order ?-2 for systems obeying detailed balance, where ? is the characteristic size of the system. Hence, the chemical Fokker-Planck equation turns out to be more accurate than the linear-noise approximation of the chemical master equation (the linear Fokker-Planck equation) which leads to mean concentration estimates accurate to order ?-1/2 and variance estimates accurate to order ?-3/2. This higher accuracy is particularly conspicuous for chemical systems realized in small volumes such as biochemical reactions inside cells. A formula is also obtained for the approximate size of the relative errors in the concentration and variance predictions of the chemical Fokker-Planck equation, where the relative error is defined as the difference between the predictions of the chemical Fokker-Planck equation and the master equation divided by the prediction of the master equation. For dimerization and enzyme-catalyzed reactions, the errors are typically less than few percent even when the steady-state is characterized by merely few tens of molecules.

Grima, Ramon; Thomas, Philipp; Straube, Arthur V.

2011-08-01

457

Chemical recognition software  

SciTech Connect

We have developed a capability to make real time concentration measurements of individual chemicals in a complex mixture using a multispectral laser remote sensing system. Our chemical recognition and analysis software consists of three parts: (1) a rigorous multivariate analysis package for quantitative concentration and uncertainty estimates, (2) a genetic optimizer which customizes and tailors the multivariate algorithm for a particular application, and (3) an intelligent neural net chemical filter which pre-selects from the chemical database to find the appropriate candidate chemicals for quantitative analyses by the multivariate algorithms, as well as providing a quick-look concentration estimate and consistency check. Detailed simulations using both laboratory fluorescence data and computer synthesized spectra indicate that our software can make accurate concentration estimates from complex multicomponent mixtures. even when the mixture is noisy and contaminated with unknowns.

Wagner, J.S.; Trahan, M.W.; Nelson, W.E.; Hargis, P.J. Jr.; Tisone, G.C.

1994-12-01

458

Reversible Chemical Kinetics Model  

NSDL National Science Digital Library

The Reversible Chemical Kinetics Model illustrates the time evolution of a reversible chemical reaction, from a given set of initial reactants concentration until chemical equilibrium is reached. The concentrations are plotted against time and the respective numerical values are periodically displayed at the data Table. As chemical equilibrium is attained, the concentrations become constant, the reaction quotient (Q) equalizes the equilibrium constant and Gibbs's energy change (G/RT) approaches zero. The Reversible Chemical Kinetics Model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the map and selecting "Open Ejs Model" from the pop-up menu item.

Fernandes, Fernando S.

2012-10-20

459

PhD Chemical Engineering MS Chemical Engineering  

E-print Network

1 PhD Chemical Engineering MS Chemical Engineering Bylaws Gene and Linda Voiland School of Chemical Engineering and Bioengineering College of Engineering and Architecture Approved by Voiland School facultyD Chemical Engineering, MS Chemical Engineering B. Discipline: Edgar, et al.1 provide a succinct description

Collins, Gary S.

460

Appendix G. Chemicals Appendix G. Chemicals G-3  

E-print Network

Appendix G. Chemicals #12;#12;Appendix G. Chemicals G-3 Appendix G. Chemicals This appendix presents basic facts about chemicals. The information is intended to be a basis for understanding the dose), not a comprehensive discussion of chemicals and their effects on the environment and biological systems. G.1

Pennycook, Steve