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1

Anion gap, anion gap corrected for albumin, base deficit and unmeasured anions in critically ill patients: implications on the assessment of metabolic acidosis and the diagnosis of hyperlactatemia  

Microsoft Academic Search

BACKGROUND: Base deficit (BD), anion gap (AG), and albumin corrected anion gap (ACAG) are used by clinicians to assess the presence or absence of hyperlactatemia (HL). We set out to determine if these tools can diagnose the presence of HL using cotemporaneous samples. METHODS: We conducted a chart review of ICU patients who had cotemporaneous arterial blood gas, serum chemistry,

Lakhmir S Chawla; Shirley Shih; Danielle Davison; Christopher Junker; Michael G Seneff

2008-01-01

2

Use of anion gap in the evaluation of a patient with metabolic acidosis.  

PubMed

High anion gap (AG) metabolic acidosis, a common laboratory abnormality encountered in clinical practice, frequently is due to accumulation of organic acids such as lactic acid, keto acids, alcohol metabolites, and reduced kidney function. The cause of high AG metabolic acidosis often is established easily using historical and simple laboratory data. Despite this, several challenges in the diagnosis and management of high AG metabolic acidosis remain, including quantifying the increase in AG, understanding the relationship between changes in AG and serum bicarbonate level, and identifying the cause of high AG metabolic acidosis when common causes are ruled out. The present case was selected to highlight the importance of the correction of AG for serum albumin level, the use of actual baseline AG rather than mean normal AG, the relationship between changes in serum bicarbonate level and AG, and a systematic diagnostic approach to uncommon causes of high AG metabolic acidosis, such as 5-oxoproline acidosis (pyroglutamic acidosis). PMID:25132207

Vichot, Alfred A; Rastegar, Asghar

2014-10-01

3

Starvation Ketoacidosis: A Cause of Severe Anion Gap Metabolic Acidosis in Pregnancy  

PubMed Central

Pregnancy is a diabetogenic state characterized by relative insulin resistance, enhanced lipolysis, elevated free fatty acids and increased ketogenesis. In this setting, short period of starvation can precipitate ketoacidosis. This sequence of events is recognized as “accelerated starvation.” Metabolic acidosis during pregnancy may have adverse impact on fetal neural development including impaired intelligence and fetal demise. Short periods of starvation during pregnancy may present as severe anion gap metabolic acidosis (AGMA). We present a 41-year-old female in her 32nd week of pregnancy, admitted with severe AGMA with pH 7.16, anion gap 31, and bicarbonate of 5?mg/dL with normal lactate levels. She was intubated and accepted to medical intensive care unit. Urine and serum acetone were positive. Evaluation for all causes of AGMA was negative. The diagnosis of starvation ketoacidosis was established in absence of other causes of AGMA. Intravenous fluids, dextrose, thiamine, and folic acid were administered with resolution of acidosis, early extubation, and subsequent normal delivery of a healthy baby at full term. Rapid reversal of acidosis and favorable outcome are achieved with early administration of dextrose containing fluids. PMID:24963418

Venkatram, Sindhaghatta; Diaz-Fuentes, Gilda

2014-01-01

4

Metabolic alkalosis from unsuspected ingestion: use of urine pH and anion gap.  

PubMed

Underlying causes of metabolic alkalosis may be evident from history, evaluation of effective circulatory volume, and measurement of urine chloride concentration. However, identification of causes may be difficult for certain conditions associated with clandestine behaviors, such as surreptitious vomiting, use of drugs or herbal supplements with mineralocorticoid activity, abuse of laxatives or diuretics, and long-term use of alkalis. In these circumstances, clinicians often are bewildered by unexplained metabolic alkalosis from an incomplete history or persistent deception by the patient, leading to misdiagnosis and poor outcome. We present a case of severe metabolic alkalosis and hypokalemia with a borderline urine chloride concentration in an alcoholic patient treated with a thiazide. The cause of the patient's metabolic alkalosis eventually was linked to surreptitious ingestion of baking soda. This case highlights the necessity of a high index of suspicion for the diverse clandestine behaviors that can cause metabolic alkalosis and the usefulness of urine pH and anion gap in its differential diagnosis. PMID:22265393

Yi, Joo-Hark; Han, Sang-Woong; Song, June-Seok; Kim, Ho-Jung

2012-04-01

5

Ethylene glycol poisoning with a normal anion gap caused by concurrent ethanol ingestion: Importance of the osmolal gap  

Microsoft Academic Search

Ethylene glycol poisoning classically presents as a metabolic acidosis with an increased anion gap. Metabolism of ethylene glycol to organic acids, and increased production of lactate, are responsible for the increased gap. We report the case of an alcohol user who consumed ethanol and ethylene glycol concurrently, and presented without acidosis, with a normal anion gap. Several hours later, when

Khawaja A. Ammar; Paul S. Heckerling

1996-01-01

6

Update on value of the anion gap in clinical diagnosis and laboratory evaluation.  

PubMed

Anion gap (AG) is a calculated value commonly used in clinical practice. It approximates the difference between the concentration of unmeasured anions (UA) and unmeasured cations (UC) in serum. At present, the reference range of anion gap has been lowered from 8-16 to 3-11 mmol/l because of the changes in technique for measuring electrolyte. However, clinicians and textbooks still refer and use the old reference value of 8-16 mmol/l. This may lead to misinterpretation of the value of anion gap. Our study updated the value of anion gap in clinical diagnosis and laboratory evaluation. Criteria for using anion gap were also suggested. We analyzed serum electrolyte using the Beckman Synchron CX5. The anion gap was calculated from the formula: [Na(+)-(Cl(-)+HCO(3)(-))]. We estimated the reference range using the non-parametric percentile estimation method. The reference range of anion gap obtained from 124 healthy volunteers was 5-12 mmol/l, which was low and confirmed the reports from other studies (3-11 mmol/l) using ion-selective electrode. From the retrospective study on the 6868 sets of serum electrolyte among hospitalized patients, we found the incidences of normal, increased, and decreased anion gaps were 59.5%, 37.6%, and 2.9%, respectively. The mean and central 90% range of increased anion gap were 16 and 13-20 mmol/l, which was lower than those reported in previous study (25 and 19-28 mmol/l). Anion gap exceeding 24 mmol/l was rare. The mean and central 90% range of decreased anion gap were 3 and 2-4 mmol/l, which were lower than those reported in previous study (6 and 3-8 mmol/l). The value of less than 2 mmol/l was rare. The most common causes of increased anion gap (hypertensive disease, chronic renal failure, malignant neoplasms, diabetes mellitus and heart diseases) and decreased anion gap (liver cirrhosis and nephrotic syndrome) in this study were similar to those in previous studies. We found two cases of IgG multiple myeloma with anion gap of 2 mmol/l. In conclusion, clinicians and laboratorians can use the anion gap as clue in quality control. They can check the incidences of increased and decreased anion gap. If one finds high incidence of increased anion gap (>24 mmol/l) or decreased anion gap (<2 mmol/l), one should check the quality control of electrolyte and whether the patients were hypoalbuminemia or hyperglobulinemia. An anion gap exceeding 24 mmol/l will suggest the presence of metabolic acidosis. It is very rare to find anion gap with the negative sign. PMID:11369334

Lolekha, P H; Vanavanan, S; Lolekha, S

2001-05-01

7

fastGapFill: efficient gap filling in metabolic networks  

PubMed Central

Motivation: Genome-scale metabolic reconstructions summarize current knowledge about a target organism in a structured manner and as such highlight missing information. Such gaps can be filled algorithmically. Scalability limitations of available algorithms for gap filling hinder their application to compartmentalized reconstructions. Results: We present fastGapFill, a computationally efficient tractable extension to the COBRA toolbox that permits the identification of candidate missing knowledge from a universal biochemical reaction database (e.g. Kyoto Encyclopedia of Genes and Genomes) for a given (compartmentalized) metabolic reconstruction. The stoichiometric consistency of the universal reaction database and of the metabolic reconstruction can be tested for permitting the computation of biologically more relevant solutions. We demonstrate the efficiency and scalability of fastGapFill on a range of metabolic reconstructions. Availability and implementation: fastGapFill is freely available from http://thielelab.eu. Contact: ines.thiele@uni.lu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:24812336

Thiele, Ines; Vlassis, Nikos; Fleming, Ronan M. T.

2014-01-01

8

Gap junction permeability: selectivity for anionic and cationic probes  

PubMed Central

Gap junction channels formed by different connexins exhibit specific permeability to a variety of larger solutes including second messengers, polypeptides, and small interfering RNAs. Here, we report the permeability of homotypic connexin26 (Cx26), Cx40, Cx43, and Cx45 gap junction channels stably expressed in HeLa cells to solutes with different size and net charge. Channel permeability was determined using simultaneous measurements of junctional conductance and the cell-cell flux of a fluorescent probe. All four connexins allowed passage of both cationic and anionic probes, but the transfer rates were connexin dependent. The negatively charged probes [Lucifer yellow (LY; median axial diameter 9.9 Å, charge ?2), carboxyfluorescein (CF; 8.2 Å; ?2), and Alexa Fluor350 (AF350, 5.4 Å; ?1)] exhibited the following permeability order: Cx43 > Cx45 > Cx26 > Cx40. In contrast, for the positively charged species permeability, the orders were as follows: Cx26 ? Cx43 ? Cx40 ? Cx45 for N,N,N-trimethyl-2-[methyl-(7-nitro-2,1,3-benzoxadiol-4-yl) amino] ethanaminium (NBD-m-TMA; 5.5 Å, +1) and Cx26 ? Cx43 ? Cx40 > Cx45 for ethidium bromide (10.3 Å, +1). Comparison of probe permeability relative to K+ revealed that Cx43 and Cx45 exhibited similar permeability for NBD-m-TMA and AF350, indicating weak charge selectivity. However, lesser transfer of CF and LY through Cx45 relative to Cx43 channels suggests stronger size-dependent discrimination of solute. The permeability of NBD-m-TMA for Cx40 and Cx26 channels was approximately three times higher than to anionic AF350 despite the fact that both have similar minor diameters, suggesting charge selectivity. In conclusion, these results confirm that channels formed from individual connexins can discriminate for solutes based on size and charge, suggesting that channel selectivity may be a key factor in cell signaling. PMID:21148413

Kanaporis, G.; Brink, P. R.

2011-01-01

9

Reliability of anion gap as an indicator of blood lactate in critically ill patients  

Microsoft Academic Search

Objective: To evaluate the sensitivity, specificity, and predictive values of an elevated anion gap as an indicator of hyperlactatemia\\u000a and to assess the contribution of blood lactate to the serum anion gap in critically ill patients. Design: Prospective study. Setting: General intensive care unit of a university hospital. Patients: 498 patients, none with ketonuria, severe renal failure or aspirin, glycol,

J. Levraut; T. Bounatirou; C. Ichai; J.-F. Ciais; P. Jambou; R. Hechema; D. Grimaud

1997-01-01

10

Spurious Hyperchloremia and Decreased Anion Gap in a Patient with Dextromethorphan Bromide  

Microsoft Academic Search

Although cold syrup containing dextromethorpan bromide is widely administered, the bromism due to cold syrup has not been reported. We report a patient who had negative anion gap with hyperchloremia and conscious loss because of daily intake of cold complex syrup (containing dextromethorphan bromide 0.4 mg\\/ml, acetaminophen 8.33 mg\\/ml) for headache for 4-5 years. The bromide content in cold complex

Yee-Yung Ng; Wen-Ling Lin; Tzen-Wen Chen; Bao-Chemg Lin; Shin-Hung Tsai; Ching-Chun Chang; Tung-Po Huang

1992-01-01

11

Metabolic Acidosis and Strong Ion Gap in Critically Ill Patients with Acute Kidney Injury  

PubMed Central

Purpose. To determine the influence of physicochemical parameters on survival in metabolic acidosis (MA) and acute kidney injury (AKI) patients. Materials and Methods. Seventy-eight MA patients were collected and assigned to AKI or non-AKI group. We analyzed the physiochemical parameters on survival at 24?h, 72?h, 1 week, 1 month, and 3 months after AKI. Results. Mortality rate was higher in the AKI group. AKI group had higher anion gap (AG), strong ion gap (SIG), and apparent strong ion difference (SIDa) values than non-AKI group. SIG value was higher in the AKI survivors than nonsurvivors and this value was correlated serum creatinine, phosphate, albumin, and chloride levels. SIG and serum albumin are negatively correlated with Acute Physiology and Chronic Health Evaluation IV scores. AG was associated with mortality at 1 and 3 months post-AKI, whereas SIG value was associated with mortality at 24?h, 72?h, 1 week, 1 month, and 3 months post-AKI. Conclusions. Whether high or low SIG values correlate with mortality in MA patients with AKI depends on its correlation with serum creatinine, chloride, albumin, and phosphate (P) levels. AG predicts short-term mortality and SIG value predicts both short- and long-term mortality among MA patients with AKI. PMID:25162029

Zheng, Cai-Mei; Liu, Wen-Chih; Zheng, Jing-Quan; Liao, Min-Tser; Ma, Wen-Ya; Lu, Chien-Lin; Lu, Kuo-Cheng

2014-01-01

12

Voltage-dependent Anion Channels Modulate Mitochondrial Metabolism in Cancer Cells  

PubMed Central

Respiratory substrates and adenine nucleotides cross the mitochondrial outer membrane through the voltage-dependent anion channel (VDAC), comprising three isoforms — VDAC1, 2, and 3. We characterized the role of individual isoforms in mitochondrial metabolism by HepG2 human hepatoma cells using siRNA. With VDAC3 to the greatest extent, all VDAC isoforms contributed to the maintenance of mitochondrial membrane potential, but only VDAC3 knockdown decreased ATP, ADP, NAD(P)H, and mitochondrial redox state. Cells expressing predominantly VDAC3 were least sensitive to depolarization induced by increased free tubulin. In planar lipid bilayers, free tubulin inhibited VDAC1 and VDAC2 but not VDAC3. Erastin, a compound that interacts with VDAC, blocked and reversed mitochondrial depolarization after microtubule destabilizers in intact cells and antagonized tubulin-induced VDAC blockage in planar bilayers. In conclusion, free tubulin inhibits VDAC1/2 and limits mitochondrial metabolism in HepG2 cells, contributing to the Warburg phenomenon. Reversal of tubulin-VDAC interaction by erastin antagonizes Warburg metabolism and restores oxidative mitochondrial metabolism. PMID:23471966

Maldonado, Eduardo N.; Sheldon, Kely L.; DeHart, David N.; Patnaik, Jyoti; Manevich, Yefim; Townsend, Danyelle M.; Bezrukov, Sergey M.; Rostovtseva, Tatiana K.; Lemasters, John J.

2013-01-01

13

Reference ranges of electrolyte and anion gap on the Beckman E4A, Beckman Synchron CX5, Nova CRT, and Nova Stat Profile Ultra.  

PubMed

The widespread use of ion-selective electrode causes the reference range of the anion gap (AG) to be lowered from 8-16 to 3-11 mmol/l. The use of the outdated reference range (8-16 mmol/l) leads to the misinterpretation of the value of the anion gap. To interpret the anion gap accurately, one must use an analyzer-specific reference range. This study established the reference ranges of the electrolyte and anion gap in four ion-selective electrode analyzers. We collected clotted and lithium-heparinized blood from 124 healthy volunteers. We determined the electrolyte in the Beckman E4A (serum), Beckman Synchron CX5 (serum), and Nova CRT (serum and plasma). The anion gap was calculated from the formula: [Na(+)-(Cl(-)+HCO3(-))]. Blood sodium, potassium and bicarbonate were determined using the Nova Stat Profile Ultra. We used the plasma chloride from the Nova CRT to calculate the value of the anion gap in the Nova Stat Profile Ultra. We established the reference ranges using the non-parametric percentile estimation method. Accuracy and precision of the electrolyte performances obtained from all analyzers were acceptable. Reference values of serum and plasma sodium, potassium, and chloride were similar in all analyzers. The value of blood sodium obtained from the Nova Stat Profile Ultra was slightly higher than the values for the serum and plasma sodium obtained from the other analyzers. The bicarbonate ranges obtained from the Nova analyzers were higher than the values obtained from the Beckman analyzers. For the anion gap, the reference ranges in this study were low but similar to other studies (3-11 mmol/l) using ion-selective electrode. However, our reference ranges were lower than the previous reference ranges obtained from the continuous-flow analyzer (8-16 or 9-18 mmol/l) incorporated with flame photometry and colorimetry techniques. PMID:11369341

Lolekha, P H; Vanavanan, S; Teerakarnjana, N; Chaichanajarernkul, U

2001-05-01

14

Survival of hydrogen anions near atomically flat metal surfaces: Band gap confinement and image state recapture effects  

NASA Astrophysics Data System (ADS)

Resonant charge transfer (RCT) between ions and surfaces is a key intermediate step in surface-chemical processes as well as in micro- and nano-fabrications on the surface. The RCT process in the collision of hydrogen anions with metal surfaces is described within a wave packet propagation methodology using Crank-Nicholson algorithm [1]. The ion-survival probability is found to strongly enhance at two different ion velocities perpendicular to the surface. The low velocity enhancement is induced from a dynamical confinement of the ion level inside the band gap, while the high velocity enhancement emerges owing to the recapture from transiently populated image states [2]. These structures are found to be somewhat sensitive to the ion's distance of closest approach to the surface and the choice of inter-atomic potentials between the ion and the surface atoms. [1] Chakraborty et al., Phys. Rev. A 70, 052903 (2004); [2] Schmitz et al., Phys. Rev. A (submitted).

Schmitz, Andrew; Shaw, John; Chakraborty, Himadri; Thumm, Uwe

2010-03-01

15

Anion Gap as a Screening Tool for Elevated Lactate in Patients with an Increased Risk of Developing Sepsis in the Emergency Department  

Microsoft Academic Search

Objectives: Serum lactate levels are a useful tool in monitoring critically ill patients, especially those who are septic. However, lactate levels are often not routinely drawn or rapidly available in some institutions. The objective of this study was to determine if a readily available anion gap (AG) could be used as a surrogate marker for abnormal lactate level in Emergency

Matthew Berkman; Jacob Ufberg; Larry A. Nathanson; Nathan I. Shapiro

2009-01-01

16

Gap-filling analysis of the iJO1366 Escherichia coli metabolic network reconstruction for discovery of metabolic functions  

PubMed Central

Background The iJO1366 reconstruction of the metabolic network of Escherichia coli is one of the most complete and accurate metabolic reconstructions available for any organism. Still, because our knowledge of even well-studied model organisms such as this one is incomplete, this network reconstruction contains gaps and possible errors. There are a total of 208 blocked metabolites in iJO1366, representing gaps in the network. Results A new model improvement workflow was developed to compare model based phenotypic predictions to experimental data to fill gaps and correct errors. A Keio Collection based dataset of E. coli gene essentiality was obtained from literature data and compared to model predictions. The SMILEY algorithm was then used to predict the most likely missing reactions in the reconstructed network, adding reactions from a KEGG based universal set of metabolic reactions. The feasibility of these putative reactions was determined by comparing updated versions of the model to the experimental dataset, and genes were predicted for the most feasible reactions. Conclusions Numerous improvements to the iJO1366 metabolic reconstruction were suggested by these analyses. Experiments were performed to verify several computational predictions, including a new mechanism for growth on myo-inositol. The other predictions made in this study should be experimentally verifiable by similar means. Validating all of the predictions made here represents a substantial but important undertaking. PMID:22548736

2012-01-01

17

Use of Sodium-Chloride Difference and Corrected Anion Gap as Surrogates of Stewart Variables in Critically Ill Patients  

PubMed Central

Introduction To investigate whether the difference between sodium and chloride ([Na+] – [Cl?]) and anion gap corrected for albumin and lactate (AGcorr) could be used as apparent strong ion difference (SIDapp) and strong ion gap (SIG) surrogates (respectively) in critically ill patients. Methods A total of 341 patients were prospectively observed; 161 were allocated to the modeling group, and 180 to the validation group. Simple regression analysis was used to construct a mathematical model between SIDapp and [Na+] – [Cl?] and between SIG and AGcorr in the modeling group. Area under the receiver operating characteristic (ROC) curve was also measured. The mathematical models were tested in the validation group. Results in the modeling group, SIDapp and SIG were well predicted by [Na+] – [Cl?] and AGcorr (R2?=?0.973 and 0.96, respectively). Accuracy values of [Na+] – [Cl?] for the identification of SIDapp acidosis (<42.7 mEq/L) and alkalosis (>47.5 mEq/L) were 0.992 (95% confidence interval [CI], 0.963–1) and 0.998 (95%CI, 0.972–1), respectively. The accuracy of AGcorr in revealing SIG acidosis (>8 mEq/L) was 0.974 (95%CI: 0.936–0.993). These results were validated by showing excellent correlations and good agreements between predicted and measured SIDapp and between predicted and measured SIG in the validation group (R2?=?0.977; bias?=?0±1.5 mEq/L and R2?=?0.96; bias?=??0.2±1.8 mEq/L, respectively). Conclusions SIDapp and SIG can be substituted by [Na+] – [Cl?] and by AGcorr respectively in the diagnosis and management of acid-base disorders in critically ill patients. PMID:23418590

Mallat, Jihad; Barrailler, Stephanie; Lemyze, Malcolm; Pepy, Florent; Gasan, Gaelle; Tronchon, Laurent; Thevenin, Didier

2013-01-01

18

Functional analysis of gapped microbial genomes: amino acid metabolism of Thiobacillus ferrooxidans.  

PubMed

A gapped genome sequence of the biomining bacterium Thiobacillus ferrooxidans strain ATCC23270 was assembled from sheared DNA fragments (3.2-times coverage) into 1,912 contigs. A total of 2,712 potential genes (ORFs) were identified in 2.6 Mbp (megabase pairs) of Thiobacillus genomic sequence. Of these genes, 2,159 could be assigned functions by using the WIT-Pro/EMP genome analysis system, most with a high degree of certainty. Nine hundred of the genes have been assigned roles in metabolic pathways, producing an overview of cellular biosynthesis, bioenergetics, and catabolism. Sequence similarities, relative gene positions on the chromosome, and metabolic reconstruction (placement of gene products in metabolic pathways) were all used to aid gene assignments and for development of a functional overview. Amino acid biosynthesis was chosen to demonstrate the analytical capabilities of this approach. Only 10 expected enzymatic activities, of the nearly 150 involved in the biosynthesis of all 20 amino acids, are currently unassigned in the Thiobacillus genome. This result compares favorably with 10 missing genes for amino acid biosynthesis in the complete Escherichia coli genome. Gapped genome analysis can therefore give a decent picture of the central metabolism of a microorganism, equivalent to that of a complete sequence, at significantly lower cost. PMID:10737802

Selkov, E; Overbeek, R; Kogan, Y; Chu, L; Vonstein, V; Holmes, D; Silver, S; Haselkorn, R; Fonstein, M

2000-03-28

19

Spectroscopy of the low-lying states of the group IIIV diatomics, AlP, GaP, InP, and GaAs via anion photodetachment spectroscopy  

E-print Network

Spectroscopy of the low-lying states of the group III­V diatomics, AlP, GaP, InP, and GaAs via The low-lying electronic states of AlP, GaP, InP, and GaAs have been probed using anion photoelectron spectroscopy and zero electronic kinetic energy spectroscopy. We observe transitions from the anion 2 and low-lying

Neumark, Daniel M.

20

Likelihood-Based Gene Annotations for Gap Filling and Quality Assessment in Genome-Scale Metabolic Models  

PubMed Central

Genome-scale metabolic models provide a powerful means to harness information from genomes to deepen biological insights. With exponentially increasing sequencing capacity, there is an enormous need for automated reconstruction techniques that can provide more accurate models in a short time frame. Current methods for automated metabolic network reconstruction rely on gene and reaction annotations to build draft metabolic networks and algorithms to fill gaps in these networks. However, automated reconstruction is hampered by database inconsistencies, incorrect annotations, and gap filling largely without considering genomic information. Here we develop an approach for applying genomic information to predict alternative functions for genes and estimate their likelihoods from sequence homology. We show that computed likelihood values were significantly higher for annotations found in manually curated metabolic networks than those that were not. We then apply these alternative functional predictions to estimate reaction likelihoods, which are used in a new gap filling approach called likelihood-based gap filling to predict more genomically consistent solutions. To validate the likelihood-based gap filling approach, we applied it to models where essential pathways were removed, finding that likelihood-based gap filling identified more biologically relevant solutions than parsimony-based gap filling approaches. We also demonstrate that models gap filled using likelihood-based gap filling provide greater coverage and genomic consistency with metabolic gene functions compared to parsimony-based approaches. Interestingly, despite these findings, we found that likelihoods did not significantly affect consistency of gap filled models with Biolog and knockout lethality data. This indicates that the phenotype data alone cannot necessarily be used to discriminate between alternative solutions for gap filling and therefore, that the use of other information is necessary to obtain a more accurate network. All described workflows are implemented as part of the DOE Systems Biology Knowledgebase (KBase) and are publicly available via API or command-line web interface. PMID:25329157

Benedict, Matthew N.; Mundy, Michael B.; Henry, Christopher S.; Chia, Nicholas; Price, Nathan D.

2014-01-01

21

Likelihood-based gene annotations for gap filling and quality assessment in genome-scale metabolic models.  

PubMed

Genome-scale metabolic models provide a powerful means to harness information from genomes to deepen biological insights. With exponentially increasing sequencing capacity, there is an enormous need for automated reconstruction techniques that can provide more accurate models in a short time frame. Current methods for automated metabolic network reconstruction rely on gene and reaction annotations to build draft metabolic networks and algorithms to fill gaps in these networks. However, automated reconstruction is hampered by database inconsistencies, incorrect annotations, and gap filling largely without considering genomic information. Here we develop an approach for applying genomic information to predict alternative functions for genes and estimate their likelihoods from sequence homology. We show that computed likelihood values were significantly higher for annotations found in manually curated metabolic networks than those that were not. We then apply these alternative functional predictions to estimate reaction likelihoods, which are used in a new gap filling approach called likelihood-based gap filling to predict more genomically consistent solutions. To validate the likelihood-based gap filling approach, we applied it to models where essential pathways were removed, finding that likelihood-based gap filling identified more biologically relevant solutions than parsimony-based gap filling approaches. We also demonstrate that models gap filled using likelihood-based gap filling provide greater coverage and genomic consistency with metabolic gene functions compared to parsimony-based approaches. Interestingly, despite these findings, we found that likelihoods did not significantly affect consistency of gap filled models with Biolog and knockout lethality data. This indicates that the phenotype data alone cannot necessarily be used to discriminate between alternative solutions for gap filling and therefore, that the use of other information is necessary to obtain a more accurate network. All described workflows are implemented as part of the DOE Systems Biology Knowledgebase (KBase) and are publicly available via API or command-line web interface. PMID:25329157

Benedict, Matthew N; Mundy, Michael B; Henry, Christopher S; Chia, Nicholas; Price, Nathan D

2014-10-01

22

Voltage-dependent anion channels modulate mitochondrial metabolism in cancer cells: regulation by free tubulin and erastin.  

PubMed

Respiratory substrates and adenine nucleotides cross the mitochondrial outer membrane through the voltage-dependent anion channel (VDAC), comprising three isoforms--VDAC1, 2, and 3. We characterized the role of individual isoforms in mitochondrial metabolism by HepG2 human hepatoma cells using siRNA. With VDAC3 to the greatest extent, all VDAC isoforms contributed to the maintenance of mitochondrial membrane potential, but only VDAC3 knockdown decreased ATP, ADP, NAD(P)H, and mitochondrial redox state. Cells expressing predominantly VDAC3 were least sensitive to depolarization induced by increased free tubulin. In planar lipid bilayers, free tubulin inhibited VDAC1 and VDAC2 but not VDAC3. Erastin, a compound that interacts with VDAC, blocked and reversed mitochondrial depolarization after microtubule destabilizers in intact cells and antagonized tubulin-induced VDAC blockage in planar bilayers. In conclusion, free tubulin inhibits VDAC1/2 and limits mitochondrial metabolism in HepG2 cells, contributing to the Warburg phenomenon. Reversal of tubulin-VDAC interaction by erastin antagonizes Warburg metabolism and restores oxidative mitochondrial metabolism. PMID:23471966

Maldonado, Eduardo N; Sheldon, Kely L; DeHart, David N; Patnaik, Jyoti; Manevich, Yefim; Townsend, Danyelle M; Bezrukov, Sergey M; Rostovtseva, Tatiana K; Lemasters, John J

2013-04-26

23

Photoelectron spectroscopy of germanium-fluorine binary cluster anions: the HOMO-LUMO gap estimation of Ge n clusters  

Microsoft Academic Search

Electronic properties of germanium-fluorine cluster anions (GenFn?; n=1–11, m=1–3) were studied using photoelectron spectroscopy (PES) with a magnetic-bottle type electron spectrometer. Compared between the PES of GenF? and those of the Gen?, it was found that the dope F atom in GenF? deprives each Gen? cluster of excess electron without any serious rearrangement of the Gen framework. The F doping

Y. Negishi; H. Kawamata; T. Hayase; M. Gomei; R. Kishi; F. Hayakawa; A. Nakajima; K. Kaya

1997-01-01

24

Proton and anion transport at the tonoplast in crassulacean-acid-metabolism plants: specificity of the malate-influx system in Kalanchoë daigremontiana  

Microsoft Academic Search

Tonoplast vesicles were prepared from leaf mesophyll homogenates of the crassulacean-acid-metabolism plant Kalanchoë daigremontiana Hamet et Perrier de la Bâthie to study the effects of anions on ATP- and inorganic-pyrophosphate (PPi)-dependent H+ transport. In the presence of gramicidin, substrate hydrolysis by the tonoplast ATPase was characteristically stimulated by chloride and inhibited by nitrate, but was unaffected by malate and a

Philip J. White; J. Andrew C. Smith

1989-01-01

25

17?-estradiol reduces the effect of metabolic inhibition on gap junction intercellular communication in rat cardiomyocytes via the estrogen receptor  

Microsoft Academic Search

The effects of 17?-estradiol (E2) on gap junction intercellular communication (GJIC) were assessed by Lucifer yellow dye coupling in cultured neonatal rat cardiomyocytes after metabolic inhibition (MI) using potassium cyanide and sodium iodoacetate. MI significantly reduced dye coupling of cardiomyocytes to 8.5% ± 0.6% of control levels, and pretreatment with E2, but not its inactive isomer 17?-estradiol, dose-dependently (EC50 =

Tun-Hui Chung; Seu-Mei Wang; Jiahn-Chun Wu

2004-01-01

26

Solving gap metabolites and blocked reactions in genome-scale models: application to the metabolic network of Blattabacterium cuenoti  

PubMed Central

Background Metabolic reconstruction is the computational-based process that aims to elucidate the network of metabolites interconnected through reactions catalyzed by activities assigned to one or more genes. Reconstructed models may contain inconsistencies that appear as gap metabolites and blocked reactions. Although automatic methods for solving this problem have been previously developed, there are many situations where manual curation is still needed. Results We introduce a general definition of gap metabolite that allows its detection in a straightforward manner. Moreover, a method for the detection of Unconnected Modules, defined as isolated sets of blocked reactions connected through gap metabolites, is proposed. The method has been successfully applied to the curation of iCG238, the genome-scale metabolic model for the bacterium Blattabacterium cuenoti, obligate endosymbiont of cockroaches. Conclusion We found the proposed approach to be a valuable tool for the curation of genome-scale metabolic models. The outcome of its application to the genome-scale model B. cuenoti iCG238 is a more accurate model version named as B. cuenoti iMP240. PMID:24176055

2013-01-01

27

Anion photoelectron spectroscopy of radicals and clusters  

E-print Network

bulk band gap to the HOMO- LUMO gap in small InP clusters isgap in the resulting anion photoelectron spectrum represents the HOMO-LUMOHOMO-LUMO spectra and photodissociation spectra of InP clusters showed that the gap

Taylor, T.R.

2011-01-01

28

Determination of sugar phosphates and nucleotides related to photosynthetic metabolism by high-performance anion-exchange liquid chromatography with fluorometric and ultraviolet detection.  

PubMed

A high-performance anion-exchange liquid chromatography system was constructed to identify sugar phosphates and nucleotides involved in photosynthetic metabolism. First sugar phosphates and nucleotides were separated by a gradient elution with boric acid and sodium phosphate, then they were detected by a fluorescence detector (as fluorescent derivatives with arginine) and UV detector, respectively. Eight authentic sugar phosphates and 11 authentic nucleotides could be analyzed using the system. The applicability of the system to the determination of the corresponding sugar phosphates and nucleotides in extracts from only five soybean leaf discs (8.95 cm2) was shown. PMID:12633603

Sawada, Shinichi; Ono, Reiko; Sato, Takayuki; Suzuki, Satoshi; Arakawa, Osamu; Kasai, Minobu

2003-03-01

29

Filling Kinetic Gaps: Dynamic Modeling of Metabolism Where Detailed Kinetic Information Is Lacking  

PubMed Central

Background Integrative analysis between dynamical modeling of metabolic networks and data obtained from high throughput technology represents a worthy effort toward a holistic understanding of the link among phenotype and dynamical response. Even though the theoretical foundation for modeling metabolic network has been extensively treated elsewhere, the lack of kinetic information has limited the analysis in most of the cases. To overcome this constraint, we present and illustrate a new statistical approach that has two purposes: integrate high throughput data and survey the general dynamical mechanisms emerging for a slightly perturbed metabolic network. Methodology/Principal Findings This paper presents a statistic framework capable to study how and how fast the metabolites participating in a perturbed metabolic network reach a steady-state. Instead of requiring accurate kinetic information, this approach uses high throughput metabolome technology to define a feasible kinetic library, which constitutes the base for identifying, statistical and dynamical properties during the relaxation. For the sake of illustration we have applied this approach to the human Red blood cell metabolism (hRBC) and its capacity to predict temporal phenomena was evaluated. Remarkable, the main dynamical properties obtained from a detailed kinetic model in hRBC were recovered by our statistical approach. Furthermore, robust properties in time scale and metabolite organization were identify and one concluded that they are a consequence of the combined performance of redundancies and variability in metabolite participation. Conclusions/Significance In this work we present an approach that integrates high throughput metabolome data to define the dynamic behavior of a slightly perturbed metabolic network where kinetic information is lacking. Having information of metabolite concentrations at steady-state, this method has significant relevance due its potential scope to analyze others genome scale metabolic reconstructions. Thus, I expect this approach will significantly contribute to explore the relationship between dynamic and physiology in other metabolic reconstructions, particularly those whose kinetic information is practically nulls. For instances, I envisage that this approach can be useful in genomic medicine or pharmacogenomics, where the estimation of time scales and the identification of metabolite organization may be crucial to characterize and identify (dis)functional stages. PMID:19305506

Resendis-Antonio, Osbaldo

2009-01-01

30

DMPFinder- Finding differentiating pathways with gaps from two groups of metabolic networks *  

E-print Network

Why some strains of a species exhibit a certain phenotype (e.g. drug resistant) but not the other strains of the same species is a critical question to answer. Studying the metabolism of the two groups of strains may discover the corresponding pathways that are conserved in the first group but not in the second group. However, only a few tools provide functions to compare two groups of metabolic networks which are usually limited to the reaction level, not the pathway level. In this paper, we formulate the DMP (Differentiating Metabolic Pathway) problem for finding conserved pathways exist in first group, but not the second group. The problem also captures the mutation in pathways and derives a measure (p-value and e-score) for evaluating the confident of the pathways. We then developed an algorithm, DMPFinder, to solve the DMP problem. Experimental results show that DMPFinder is able to identify pathways that are critical for the first group to exhibit a certain phenotype which is absent in the other group. Some of these pathways cannot be identified by other tools which only consider reaction level or do not take into account possible mutations among species. The software is available at:

Henry C. M. Leung; S. Y. Leung; Carlos L. Xiang; S. M. Yiu

31

Uniport of Anionic Citrate and Proton Consumption in Citrate Metabolism Generates a Proton Motive Force in Leuconostoc oenos  

Microsoft Academic Search

The mechanism and energetics of citrate transport in Leuconostoc oenos were investigated. Resting cells of L. oenos generate both a membrane potential (??) and a pH gradient (?pH) upon addition of citrate. After a lag time, the internal alkalinization is followed by a continuous alkalinization of the external medium, demonstrating the involvement of proton-consuming reactions in the metabolic breakdown of

Wil N. Konings; Juke S. Lolkema; Helena Santos; Bert Poolman; Ana Ramos

1994-01-01

32

Effect of carbonate anion on cytochrome P450 2D6-mediated metabolism in vitro: the potential role of multiple oxygenating species.  

PubMed

Studies were designed to investigate various anions and their effects on cytochrome P450 2D6-mediated metabolism in vitro. Incubations were initially performed in buffered phosphate, carbonate, sulfate, and acetate solutions (50mM, pH 7.4), with CYP2D6 substrates dextromethorphan, 7-methoxy-4-(aminomethyl)-coumarin (MAMC), (S,S)-3-[3-(methylsulfonyl)phenyl]-1-propylpiperidine hydrochloride [(-)-OSU6162], and amitriptyline. Dextromethorphan and MAMC O-dealkylation activity in buffered carbonate was approximately 25 and 38%, respectively, relative to phosphate, while activity in sulfate and acetate buffers displayed minor differences. In contrast, N-dealkylation reactions for both (-)-OSU6162 and amitriptyline were unaffected by the presence of carbonate, and the other anions tested. Subsequent kinetic studies revealed that the basis of reduced turnover of dextromethorphan was primarily a V(max) effect, as the V(max) for the rate was 16.9 and 5.6 pmol/min/pmol P450 in phosphate and carbonate, respectively. Interestingly, similar rates of dextromethorphan O-demethylation in phosphate and carbonate were observed when reactions were supported by cumene hydroperoxide (CuOOH). Furthermore, it was observed that while CuOOH could equally support dextromethorphan O-demethylation compared to NADPH, amitriptyline N-demethylation was only minimally supported. Finally, intramolecular kinetic isotope effect (KIE) experiments with amitriptyline-d3 in CuOOH-supported reactions yielded a k(H)/k(D) of 5.2, substantially higher than in phosphate and carbonate supported by NADPH (k(H)/k(D)=1.5). Overall, results suggest that carbonate disrupts the relative ratios of the potential P450 oxygenating species, which differentially catalyze O- and N-dealkylation reactions mediated by CYP2D6. PMID:12941298

Hutzler, J Matthew; Powers, Frank J; Wynalda, Michael A; Wienkers, Larry C

2003-09-15

33

NMR studies on 4n. pi. -conjugated polycyclic anions: The relationship between the HOMO-LUMO gap, paratropicity and electronic structure  

SciTech Connect

Among the observable phenomena, the most useful definition of aromatic nature seems to be based on the magnetic anisotropy of the system under investigation as deduced from the /sup 1/H NMR parameters. Antiaromatic 4n..pi.. systems are expected to be paratropic and to exhibit high-field shifts in the /sup 1/H NMR spectrum in contrast to the diatropic (down-field) shift of the (4n+2)..pi.. systems. Although the diatropic shift revealed by (4n+2)..pi.. electron species is well established, the experimental support for the relationship between paratropicity and antiaromaticity is by far less satisfactory. This paper presents a correlation between a theoretical and an experimental criterion for paratropicity and its relationship to the antiaromatic character of 4n..pi.. carbocyclic and heterodianions. This correlation leads to a new theoretical index for antiaromaticity, namely the extent of the HOMO-LUMO energy gap. An unequivocal correlation between the degree of paratropicity experienced by the 4n..pi.. dianions and the HOMO-LUMO energy gap is manifested by the line shape and the chemical shifts (4b) of their /sup 1/H NMR bands. The paratropicity and delocalization pattern of the dianions and their relationship to the system's topology are demonstrated. A gradual structural deviation from the symmetrical triphenylene dianion to less symmetrical systems influences the system's paratropicity. The partitioning of the polycyclic dianions into charged and uncharged components in a way which reduces the paratropic effect is demonstrated. The authors believe that this partitioning is another manifestation of the tendency of aromatic systems to remain so.

Rabinovita, M.; Cohen, Y.

1986-09-01

34

Metabolism  

MedlinePLUS

... Some metabolic diseases and conditions include: Hyperthyroidism (pronounced: hi-per- thigh -roy-dih-zum). Hyperthyroidism is caused ... or through surgery or radiation treatments. Hypothyroidism (pronounced: hi-po- thigh -roy-dih-zum) . Hypothyroidism is caused ...

35

Filling Knowledge Gaps in Biological Networks: integrating global approaches to understand H2 metabolism in Chlamydomonas reinhardtii - Final Report  

SciTech Connect

The green alga Chlamydomonas reinhardtii (Chlamydomonas) has numerous genes encoding enzymes that function in fermentative pathways. Among these genes, are the [FeFe]-hydrogenases, pyruvate formate lyase, pyruvate ferredoxin oxidoreductase, acetate kinase, and phosphotransacetylase. We have systematically undertaken a series of targeted mutagenesis approaches to disrupt each of these key genes and �¢����omics�¢���� techniques to characterize alterations in metabolic flux. Funds from DE-FG02-07ER64423 were specifically leveraged to generate mutants with disruptions in the genes encoding the [FeFe]-hydrogenases HYDA1 and HYDA2, pyruvate formate lyase (PFL1), and in bifunctional alcohol/aldehyde alcohol dehydrogenase (ADH1). Additionally funds were used to conduct global transcript profiling experiments of wildtype Chlamydomonas cells, as well as of the hydEF-1 mutant, which is unable to make H2 due to a lesion in the [FeFe]-hydrogenase biosynthetic pathway. In the wildtype cells, formate, acetate and ethanol are the dominant fermentation products with traces of CO2 and H2 also being produced. In the hydEF-1 mutant, succinate production is increased to offset the loss of protons as a terminal electron acceptor. In the pfl-1 mutant, lactate offsets the loss of formate production, and in the adh1-1 mutant glycerol is made instead of ethanol. To further probe the system, we generated a double mutant (pfl1-1 adh1) that is unable to synthesize both formate and ethanol. This strain, like the pfl1 mutants, secreted lactate, but also exhibited a significant increase in the levels of extracellular glycerol, acetate, and intracellular reduced sugars, and a decline in dark, fermentative H2 production. Whereas wild-type Chlamydomonas fermentation primarily produces formate and ethanol, the double mutant performs a complete rerouting of the glycolytic carbon to lactate and glycerol. Lastly, transcriptome data have been analysed for both the wildtype and hydEF-1, that correlate with our observed fermentative metabolites. Intriguingly, over half of the most differentially regulated genes are of unknown function.

Posewitz, Matthew C

2011-06-30

36

Anions in Crystal Engineering  

SciTech Connect

This tutorial review presents a current account of anions in crystal engineering, organized around two main questions: (i) how do anions influence and control crystal structures, and (ii) how do crystal environments recognize and select anions? The first part pertains to deliberate assembly of new crystalline materials using anionic components, by taking advantage of the strong and directional interactions of anions in the solid state. Along this line, the various structural roles of anions in crystals are examined. The second question is related to selective separation of anions by crystallization, by exploiting chemical recognition phenomena in the well-defined and highly structured environment inside crystals.

Custelcean, Radu [ORNL

2010-01-01

37

Unraveling the toxicity mechanisms of the herbicide diclofop-methyl in rice: modulation of the activity of key enzymes involved in citrate metabolism and induction of cell membrane anion channels.  

PubMed

Residual soil concentrations of the herbicide diclofop-methyl (DM) can be toxic to other nontarget plant species, but the toxicity mechanisms at play are not fully understood. In the present study, we analyzed the toxic effect of DM on root growth and metabolism in the rice species Oryza sativa. The results show that a 48-h exposure to a trace level (5 ?g/L) of DM inhibits rice root growth by almost 70%. A 48-h exposure to 5 ?g/L DM also leads to an ?2.5-fold increase in citrate synthase (CS) activity (and CS gene transcription) and an ?2-fold decrease in the citrate lyase gene transcripts, which lead to an increase in the intracellular concentration of citrate and in citrate exudation rate. Addition of a specific inhibitor of cell membrane anion channel, anthracene-9-carboxylic acid, decreased citrate release in the culture, suggesting that DM-induced citrate loss from the cells is mediated by a specific membrane-bound channel protein. This study brings new insights into the key biochemical mechanisms leading to DM toxicity in rice. PMID:25307187

Ding, Haiyan; Lu, Haiping; Lavoie, Michel; Xie, Jun; Li, Yali; Lv, Xiaolu; Fu, Zhengwei; Qian, Haifeng

2014-11-01

38

Quantum chemical approach to estimating the thermodynamics of metabolic reactions.  

PubMed

Thermodynamics plays an increasingly important role in modeling and engineering metabolism. We present the first nonempirical computational method for estimating standard Gibbs reaction energies of metabolic reactions based on quantum chemistry, which can help fill in the gaps in the existing thermodynamic data. When applied to a test set of reactions from core metabolism, the quantum chemical approach is comparable in accuracy to group contribution methods for isomerization and group transfer reactions and for reactions not including multiply charged anions. The errors in standard Gibbs reaction energy estimates are correlated with the charges of the participating molecules. The quantum chemical approach is amenable to systematic improvements and holds potential for providing thermodynamic data for all of metabolism. PMID:25387603

Jinich, Adrian; Rappoport, Dmitrij; Dunn, Ian; Sanchez-Lengeling, Benjamin; Olivares-Amaya, Roberto; Noor, Elad; Even, Arren Bar; Aspuru-Guzik, Alán

2014-01-01

39

Anion exchange membrane  

DOEpatents

An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

2013-05-07

40

Final Report: Filling Knowledge Gaps in Biological Networks: Integrated Global Approaches to Understand H{sub 2} Metabolism in Chlamydomonas Reinhardtii  

SciTech Connect

The major goal of our part of this project has been to generate mutants in fermentation metabolism and begin to decipher how lesions in the pathways associated with fermentation metabolism impact both H{sub 2} production and the production of other metabolites that accumulate as cells become anoxic. We are also trying to understand how metabolic pathways are regulated as O{sub 2} in the environment becomes depleted.

Grossman, Arthur

2012-05-01

41

A Case of Chronic Ethylene Glycol Intoxication Presenting without Classic Metabolic Derangements  

PubMed Central

Acute ethylene glycol ingestion classically presents with high anion gap acidosis, elevated osmolar gap, altered mental status, and acute renal failure. However, chronic ingestion of ethylene glycol is a challenging diagnosis that can present as acute kidney injury with subtle physical findings and without the classic metabolic derangements. We present a case of chronic ethylene glycol ingestion in a patient who presented with acute kidney injury and repeated denials of an exposure history. Kidney biopsy was critical to the elucidation of the cause of his worsening renal function. PMID:25215251

Toth-Manikowski, Stephanie M.; Menn-Josephy, Hanni

2014-01-01

42

Molecular Anions Jack Simons  

E-print Network

. Introduction to Molecular Anions I. Anions Have Very Different Valence-Region Electronic Potential Energies. The multiconfigurational self-consistent field (MCSCF) method B. The configuration interaction (CI) method C. The Møller Dipole Models B. Binding to Real Molecules C. Summary II. Binding an Electron to Quadrupolar Molecules A

Simons, Jack

43

Bridging the gap between protein-tyrosine phosphorylation networks, metabolism and physiology in liver-specific PTP1b deletion mice  

E-print Network

Metabolic syndrome describes a complex set of obesity-related disorders that enhance diabetes, cardiovascular, and mortality risk. Studies of liver-specific protein-tyrosine phosphatase lb (PTPlb) deletion mice (L-PTPlb-/-) ...

Miraldi, Emily R. (Emily Rae)

2012-01-01

44

Epinephrine suppresses rap1B.GAP-activated GTPase activity in human platelets.  

PubMed Central

Lysate from quiescent platelets promotes rapid hydrolysis of [gamma-32P]GTP bound to rap1B. Various platelet agonists, including platelet-activating factor, phorbol 12,13-dibutyrate, alpha-thrombin, epinephrine, ADP, and iloprost, that affect platelet metabolism by different signal transduction pathways were used to stimulate intact platelets and study their effects on rap1B.GAP-activated GTPase activity (GAP, GTPase-activating protein). Only epinephrine was found to dramatically decrease not only the rate but also the amount of hydrolysis of rap1B-bound GTP activated by rap1B.GAP. This effect was dose dependent and occurred rapidly. The suppression of GTPase activity was specific for rap1B.GAP in that ras.GAP- and rap2B.GAP-activated GTPase activity were not affected by epinephrine stimulation. This effect appears to be mediated by the alpha 2-adrenergic receptor, as evidenced by a similar suppression of GTPase activity by stimulating platelets with the synthetic alpha 2-adrenergic receptor agonist UK14304 (bromoxidine). Furthermore, the selective alpha 2-adrenergic receptor antagonist yohimbine blocked the suppression of GTPase activity expressed in epinephrine-stimulated cell lysates. No apparent changes in the patterns of protein expression or tyrosine phosphorylation were observed. Although the migration characteristics upon anion-exchange chromatography of rap1B.GAP and ras.GAP activities were unaffected by epinephrine stimulation, the specific activity of rap1B.GAP was noticeably decreased with 250 and 500 microM epinephrine. These results suggest a possible role for rap1B and rap1B.GAP in epinephrine-stimulated signal transduction. PMID:1313568

Marti, K B; Lapetina, E G

1992-01-01

45

Gap Winds  

NSDL National Science Digital Library

This module provides a basic understanding of why gap winds occur, their typical structures, and how gap wind strength and extent are controlled by larger-scale, or synoptic, conditions. You will learn about a number of important gap flows in coastal regions around the world, with special attention given to comprehensively documented gap wind cases in the Strait of Juan de Fuca and the Columbia River Gorge. Basic techniques for evaluating and predicting gap flows are presented. The module reviews the capabilities and limitations of the current generation of mesoscale models in producing realistic gap winds. By the end of this module, you should have sufficient background to diagnose and forecast gap flows around the world, and to use this knowledge to understand their implications for operational decisions. Other features in this module include a concise summary for quick reference and a final exam to test your knowledge. Like other modules in the Mesoscale Meteorology Primer, this module comes with audio narration, rich graphics, and a companion print version.

Comet

2003-03-20

46

Conditioned medium of human adipose-derived mesenchymal stem cells mediates protection in neurons following glutamate excitotoxicity by regulating energy metabolism and GAP-43 expression.  

PubMed

Glutamate excitotoxicity has been implicated as one of the pathological mechanisms contributing to neuronal cell death and is involved in many neurological disorders. Stem cell transplantation is a promising approach for the treatment of nervous system damage or diseases. Previous studies have shown that mesenchymal stem cells (MSCs) have important therapeutic effects in experimental animal and preclinical disease model of central nervous system pathology. However, it is not well understood whether neurogenesis of MSCs or MSC conditioned-medium (CM) containing microparticles mediates therapeutic effects. Here, we investigated the neuroprotective effects of human adipose-derived MSCs (AMSCs) on cortical neurons using models of glutamate excitotoxicity. Following exposure to glutamate (100 ?M, 15 min), cortical neurons were co-cultured with either AMSCs separated by a semiporous membrane (prohibiting direct cell-cell contact) or with AMSC-CM for 18 h. Compared to untreated control groups, AMSCs and AMSC-CM partially and similarly reduced neuronal cell damages, as indicated by reduced LDH release, a decreased number of trypan-positive cells and a decline in the number of apoptotic nuclei. Protection by CM was associated with increased GAP-43 expression and an elevated number of GAP-43-positive neurites. Furthermore, CM increased levels of ATP, NAD(+) and NADH and the ratio of NAD(+)/NADH, while preventing a glutamate-induced decline in mitochondrial membrane potential. These results demonstrate that AMSC-CM mediates direct neuroprotection by inhibiting neuronal cell damage/apoptosis, promoting nerve regeneration and repair, and restoring bioenergy following energy depletion caused by glutamate excitotoxicity. PMID:24458787

Hao, Peng; Liang, Zhanhua; Piao, Hua; Ji, Xiaofei; Wang, Yachen; Liu, Yong; Liu, Rutao; Liu, Jing

2014-03-01

47

REVIEW ARTICLE Molecular Anions  

E-print Network

REVIEW ARTICLE Molecular Anions Jack Simons Chemistry Department, Henry Eyring Center for Theoretical Chemistry, UniVersity of Utah, Salt Lake City, Utah ReceiVed: December 5, 2007; ReVised Manuscript in close collaboration with experiment in this field. In this article, many of the experimental

Simons, Jack

48

Ethylene glycol poisoning: a rare but life-threatening cause of metabolic acidosis—a single-centre experience  

PubMed Central

Background. Intoxication with ethylene glycol happen all around the world and without rapid recognition and early treatment, mortality from this is high. Methods. In our study, we retrospectively analysed six cases of ethylene glycol intoxication in our department. We measured ethylene glycol or glycolate levels, lactate levels and calculated the osmolal and anion gap. Results. Data from six patients admitted to the nephrology department between 1999 and 2011 with ethylene glycol poisoning are reported. All patients were men. The mean pH on admission was 7.15 ± 0.20 and the anion and osmolal gap were elevated in five of six patients. Four patients had an acute kidney injury and one patient had an acute-on-chronic kidney injury. All patients survived and after being discharged, two patients required chronic intermittent haemodialysis. Interestingly, at the time of admission, all patients had elevated lactate levels but there was no linear regression between toxic levels and lactate levels and no linear correlation was found between initial lactate levels and anion gap and osmolal gap. Conclusions. The initial diagnosis of ethylene glycol poisoning is difficult and poisoning with ethylene glycol is rare but life threatening and needs rapid recognition and early treatment. Therefore, intoxication with ethylene glycol should not be misdiagnosed as lactic acidosis in patients with metabolic acidosis and elevated lactate levels.

Kimmel, Martin; Alscher, Mark Dominik; Braun, Niko

2012-01-01

49

Chemiluminescence and superoxide anion production by leukocytes from chronic hemodialysis patients  

Microsoft Academic Search

Chemiluminescence and superoxide anion production by leukocytes from chronic hemodialysis patients. During phagocytosis or in response to a soluble stimulus, polymorphonuclear leukocytes (PMN) undergo a burst of oxidative metabolism involved intimately in antimicrobial activity. Superoxide anion produced during the burst is bactericidal either directly or as an intermediate metabolite. In addition, stimulated PMN's emit light or chemiluminescence (CL). CL is

Elizabeth E Ritchey; John D Wallin; Sudhir V Shah

1981-01-01

50

Use of Hydrochloric Acid as a Source of Anions for Prevention of Milk Fever1  

Microsoft Academic Search

Diets that contain high amounts of K induce milk fever by alkalinizing the blood of the cow, reducing the ability of homeostatic mechanisms to maintain normal blood concentrations of Ca. The addition of anions to the diet induces metabolic acidosis, which counteracts the alkalinizing effect of the high cation diets commonly fed to cows. Currently, anions are usually added as

J. P. Goff; R. L. Horst

1998-01-01

51

Metabolic acidosis mimicking diabetic ketoacidosis after use of calorie-free mineral water.  

PubMed

A previously healthy boy was admitted with fever, tachycardia, dyspnea, and was vomiting. A blood test showed a severe metabolic acidosis with pH 7.08 and an anion gap of 36 mmol/L. His urine had an odor of acetone. The serum glucose was 5.6 mmol/L, and no glucosuria was found. Diabetic ketoacidosis could therefore be eliminated. Lactate level was normal. Tests for the most common metabolic diseases were negative. Because of herpes stomatitis, the boy had lost appetite and only been drinking Diet Coke and water the last days. Diet Coke or Coca-Cola Light is sweetened with a blend containing cyclamates, aspartame, and acesulfame potassium, all free of calories. The etiology of the metabolic acidosis appeared to be a catabolic situation exaggerated by fasting with no intake of calories. The elevated anion gap was due to a severe starvation ketoacidosis, mimicking a diabetic ketoacidosis. Pediatricians should recommend carbohydrate/calorie-containing fluids for rehydration of children with acute fever, diarrhea, or illness. PMID:22457081

Dahl, Gry T; Woldseth, Berit; Lindemann, Rolf

2012-09-01

52

Quantifying the role of anion-? interactions in anion-? catalysis.  

PubMed

Matile et al. introduced the concept of anion-? catalysis [Angew. Chem., Int. Ed. 2013, 52, 9940; J. Am. Chem. Soc. 2014, 136, 2101], reporting naphthalene diimide (NDI)-based organocatalysts for the Kemp elimination reaction. We report computational analyses of the operative noncovalent interactions, revealing that anion-? interactions actually increase the activation barriers for some of these catalyzed reactions. We propose new catalysts that are predicted to achieve significant lowering of the activation energy through anion-? interactions. PMID:24915527

Lu, Tongxiang; Wheeler, Steven E

2014-06-20

53

Formation of interstellar anions  

NASA Astrophysics Data System (ADS)

Formation of interstellar anions: M.L. Senent. The recent detection of negative charged species in the ISM1 has instigated enthusiasm for anions in the astrophysical community2. Many of these species are new and entail characterization. How they are formed in astrophysical sources is a question of major relevance. The anion presence in ISM was first predicted theoretically on the basis of electron affinities and on the negative linear chain molecular stabilities. Although very early, they were considered in astrochemical models3-4, their discovery is so recent because their abundances seem to be relatively low. These have to be understood in terms of molecular stabilities, reaction probabilities and radiative and collisional excitations. Then, we present our theoretical work on even carbon chains type Cn and CnH (n=2,4,6) focused to the understanding of anion abundances. We use highly correlated ab initio methods. We performed spectroscopic studies of various isomers that can play important roles as intermediates5-8. In previous papers9-10, we compared C2H and C2H- collisional rates responsible for observed line intensities. Actually, we study hydrogen attachment (Cn +H ? CnH and Cn- +H ? CnH-) and associative detachment processes (Cn- +H ? CnH +e-) for 2, 4 and 6 carbon atom chains11. [1] M.C.McCarthy, C.A.Gottlieb, H.Gupta, P.Thaddeus, Astrophys.J, 652, L141 (2006) [2] V.M.Bierbaum, J.Cernicharo, R.Bachiller, eds., 2011, pp 383-389. [3] A. Dalgarno, R.A. Mc Cray, Astrophys.J,, 181, 95 (1973) [4] E. Herbst E., Nature, 289, 656 (1981); [5] H.Massó, M.L.Senent, P.Rosmus, M.Hochlaf, J.Chem.Phys., 124, 234304 (2006) [6] M.L.Senent, M.Hochlaf, Astrophys. J. , 708, 1452(2010) [7] H.Massó, M.L.Senent, J.Phys.Chem.A, 113, 12404 (2009) [8] D. Hammoutene, M.Hochlaf, M.L.Senent, submitted. [9] A. Spielfiedel, N. Feautrier, F. Najar, D. ben Abdallah, F. Dayou, M.L. Senent, F. Lique, Mon.Not.R.Astron.Soc., 421, 1891 (2012) [10] F.Dumouchel, A, Spielfieldel , M.L.Senent, N.Feautrier, Chem. Phys. Lett., 533, 6 (2012) [11] M.L.Senent, M.Hochlaf, submitted

Senent, Maria Luisa

2012-05-01

54

Anion permselective membrane  

NASA Technical Reports Server (NTRS)

The efforts on the synthesis of polymer anion redox membranes were mainly concentrated in two areas, membrane development and membrane fabrication. Membrane development covered the preparation and evaluation of experimental membranes systems with improved resistance stability and/or lower permeability. Membrane fabrication covered the laboratory scale production of prime candidate membranes in quantities of up to two hundred and sizes up to 18 inches x 18 inches (46 cm x 46 cm). These small (10 in x 11 in) and medium sized membranes were mainly for assembly into multicell units. Improvements in processing procedures and techniques for preparing such membrane sets lifted yields to over 90 percent.

Hodgdon, R. B.; Waite, W. A.

1980-01-01

55

Anion permselective membrane  

NASA Technical Reports Server (NTRS)

The synthesis and fabrication of polymeric anion permselective membranes for redox systems are discussed. Variations of the prime candidate anion membrane formulation to achieve better resistance and/or lower permeability were explored. Processing parameters were evaluated to lower cost and fabricate larger sizes. The processing techniques to produce more membranes per batch were successfully integrated with the fabrication of larger membranes. Membranes of about 107 cm x 51 cm were made in excellent yield. Several measurements were made on the larger sample membranes. Among the data developed were water transport and transference numbers for these prime candidate membranes at 20 C. Other work done on this system included characterization of a number of specimens of candidate membranes which had been returned after service lives of up to sixteen months. Work with new polymer constituents, with new N.P.'s, catalysts and backing fabrics is discussed. Some work was also done to evaluate other proportions of the ingredients of the prime candidate system. The adoption of a flow selectivity test at elevated temperature was explored.

Hodgdon, R. B.; Waite, W. A.

1982-01-01

56

Dynamic chemistry of anion recognition  

SciTech Connect

In the past 40 years, anion recognition by synthetic receptors has grown into a rich and vibrant research topic, developing into a distinct branch of Supramolecular Chemistry. Traditional anion receptors comprise organic scaffolds functionalized with complementary binding groups that are assembled by multistep organic synthesis. Recently, a new approach to anion receptors has emerged, in which the host is dynamically self-assembled in the presence of the anionic guest, via reversible bond formation between functional building units. While coordination bonds were initially employed for the self-assembly of the anion hosts, more recent studies demonstrated that reversible covalent bonds can serve the same purpose. In both cases, due to their labile connections, the molecular constituents have the ability to assemble, dissociate, and recombine continuously, thereby creating a dynamic combinatorial library (DCL) of receptors. The anionic guests, through specific molecular recognition, may then amplify (express) the formation of a particular structure among all possible combinations (real or virtual) by shifting the equilibria involved towards the most optimal receptor. This approach is not limited to solution self-assembly, but is equally applicable to crystallization, where the fittest anion-binding crystal may be selected. Finally, the pros and cons of employing dynamic combinatorial chemistry (DCC) vs molecular design for developing anion receptors, and the implications of both approaches to selective anion separations, will be discussed.

Custelcean, Radu [ORNL

2012-01-01

57

Anion permselective membrane  

NASA Technical Reports Server (NTRS)

The objective of NAS 3-20108 was the development and evaluation of improved anion selective membranes useful as efficient separators in a redox power storage cell system being constructed. The program was divided into three parts, (a) optimization of the selected candidate membrane systems, (b) investigation of alternative membrane/polymer systems, and (c) characterization of candidate membranes. The major synthesis effort was aimed at improving and optimizing as far as possible each candidate system with respect to three critical membrane properties essential for good redox cell performance. Substantial improvements were made in 5 candidate membrane systems. The critical synthesis variables of cross-link density, monomer ratio, and solvent composition were examined over a wide range. In addition, eight alternative polymer systems were investigated, two of which attained candidate status. Three other alternatives showed potential but required further research and development. Each candidate system was optimized for selectivity.

Alexander, S.; Hodgdon, R. B.

1977-01-01

58

Diffuse large B-cell lymphoma: A metabolic disorder?  

PubMed Central

Patient Male, 81 Final Diagnosis: Non-Hodgkin lymphoma Symptoms: General weakness • hypoglycemia • metabolic acidosis Medication: — Clinical Procedure: — Specialty: Hematology Objective: Challenging differential diagnosis Background: B cell lymphoma constitutes 80–85% of cases of Non Hodgkin’s lymphoma in the Untied States. Metabolic complications may arise from the disease itself or through its end organ involvement. Case Report: We describe a case of a diffuse large B cell lymphoma diagnosed by abdominal computed tomography after it initially presented as hypoglycemia not correctable by dextrose infusion that instead resulted in increased anion gap metabolic acidosis with elevated lactate levels. Conclusions: The case illustrates how lymphomas can present unusually with hypoglycemia and lactic acidosis, the latter being an ominous sign that can occur without liver involvement. In this regard, the case demonstrates the metabolic sequelae of lymphoma that should raise suspicion for an underlying process. This has implications for diagnosis, treatment, and patient survival. Attention should be paid especially in the primary care setting in order to minimize delays in diagnosis. PMID:24349605

Tanios, Georges; Aranguren, Ines M.; Goldstein, Jack S.; Patel, Chirag B.

2013-01-01

59

Hydrogen in anion vacancies of semiconductors  

NASA Astrophysics Data System (ADS)

Density-functional calculations show that, depending on the anion size, hydrogen in anion vacancies of various II-VI semiconductors can be either twofold or fourfold coordinated and has either amphoteric or shallow donor character. In general, the multicoordination of hydrogen in an anion vacancy is the indication of an anionic H, H- ion, in the relatively ionic environment. In more covalent semiconductors, H would form a single cation-H bond in the anion vacancy.

Du, Mao-Hua; Singh, David J.

2009-05-01

60

Hydrogen in anion vacancies of semiconductors  

SciTech Connect

Density functional calculations show that, depending on the anion size, hydrogen in anion vacancies of various II-VI semiconductors can be either two-fold or four-fold coordinated, and has either amphoteric or shallow donor character. In general, the multi-coordination of hydrogen in an anion vacancy is the indication of an anionic H, H { ion, in the relatively ionic environment. In more covalent semiconductors, H would form a single cation-H bond in the anion vacancy.

Du, Mao-Hua [ORNL; Singh, David J [ORNL

2009-01-01

61

Effect of bile anionic polypeptidic fraction on the fate of cholesterol carried by liposomes in the rat  

SciTech Connect

(/sup 14/C)Cholesterol associated with liposomes with or without anionic polypeptidic fraction was administered intravenously to the rat. The cholesterol originated from liposomes including anionic polypeptidic fraction is secreted in bile much later, is stored in liver in higher quantity, and is metabolized into bile salts in lesser quantity during the 4 hr of experimentation than the cholesterol issued from liposomes exempt of anionic polypeptidic fraction. From these results it can be postulated that the cholesterol associated with liposomes containing anionic polypeptidic fraction might be directed in a particular liver pathway.

Martigne, M.; Domingo, N.; Chanussot, F.; Nalbone, G.; Lafont, H.; Hauton, J.

1988-02-01

62

Origin of Axon Membrane Hyperpolarization under Sucrose-Gap  

PubMed Central

One of the disadvantages of the sucrose-gap method for measuring membrane potentials with extracellular electrodes is a membrane hyperpolarization of the order of 30 to 60 mv, as compared with the resting potential obtained with intracellular microelectrodes in the absence of a sucrose-gap. In the present study the contribution of the sucrose-sea water junction potential to this hyperpolarization effect has been evaluated by comparing the effects on the resting potential of several anion and cation substitutions in the sea water bathing the lobster giant axon under sucrose-gap. Measurements with microelectrodes demonstrate a significant liquid junction potential between sucrose and standard artificial sea water. The value of this liquid junction potential as well as the measured resting membrane potential varies as a function of the anions and cations substituted in the sea water. Both the liquid junction potential and the sucrose-gap-induced hyperpolarization can be eliminated by using a low mobility anion to replace most of the chloride in sea water while the normal cation content remains unchanged. These data provide evidence that loop currents at the sucrose-sea water-axon junctions are at least partly responsible for membrane hyperpolarization under a sucrose gap. PMID:19210970

Blaustein, M. P.; Goldman, D. E.

1966-01-01

63

Anion separation with metal-organic frameworks  

SciTech Connect

The application of metal-organic frameworks (MOFs) to anion separations with a special emphasis on anion selectivity is reviewed. The coordination frameworks are classified on the basis of the main interactions to the included anion, from weak and non-specific van der Waals forces to more specific interactions such as coordination to Lewis acid metal centers or hydrogen bonding. The importance of anion solvation phenomena to the observed anion selectivities is highlighted, and strategies for reversing the Hofmeister bias that favors large, less hydrophilic anions, and for obtaining peak selectivities based on shape recognition are delineated. Functionalization of the anion-binding sites in MOFs with strong and directional hydrogen-bonding groups that are complementary to the included anion, combined with organizational rigidity of the coordination framework, appears to be the most promising approach for achieving non-Hofmeister selectivity.

Custelcean, Radu [ORNL; Moyer, Bruce A [ORNL

2007-01-01

64

Ion exchange polymers for anion separations  

DOEpatents

Anion exchange resins including at least two positively charged sites and a ell-defined spacing between the positive sites are provided together with a process of removing anions or anionic metal complexes from aqueous solutions by use of such resins. The resins can be substituted poly(vinylpyridine) and substituted polystyrene.

Jarvinen, Gordon D. (Los Alamos, NM); Marsh, S. Fredric (Los Alamos, NM); Bartsch, Richard A. (Lubbock, TX)

1997-01-01

65

Ion exchange polymers for anion separations  

DOEpatents

Anion exchange resins including at least two positively charged sites and a well-defined spacing between the positive sites are provided together with a process of removing anions or anionic metal complexes from aqueous solutions by use of such resins. The resins can be substituted poly(vinylpyridine) and substituted polystyrene.

Jarvinen, G.D.; Marsh, S.F.; Bartsch, R.A.

1997-09-23

66

The anion-binding polyanion: a molecular cobalt vanadium oxide with anion-sensitive visual response.  

PubMed

An anionic molecular cobalt vanadium oxide cluster, (n-Bu4N)3[Co(AcO)V4O12] and its use as anion binding site is reported. Cluster formation is controlled by an anion-dependent dynamic solution equilibrium. Reversible anion binding in solution leads to significant spectral changes, allowing the ratiometric optical detection of the anion concentration in situ, even under harsh thermal conditions (T = 90 °C). Comparative studies showed that the spectral response is dependent on the type of anion so that carboxylates, weakly coordinating anions and halides can be distinguished. PMID:24910130

Seliverstov, Andrey; Forster, Johannes; Heiland, Magdalena; Unfried, Johannes; Streb, Carsten

2014-07-25

67

Polymerization of anionic wormlike micelles.  

PubMed

Polymerizable anionic wormlike micelles are obtained upon mixing the hydrotropic salt p-toluidine hydrochloride (PTHC) with the reactive anionic surfactant sodium 4-(8-methacryloyloxyoctyl)oxybenzene sulfonate (MOBS). Polymerization captures the cross-sectional radius of the micelles (approximately 2 nm), induces micellar growth, and leads to the formation of a stable single-phase dispersion of wormlike micellar polymers. The unpolymerized and polymerized micelles were characterized using static and dynamic laser light scattering, small-angle neutron scattering, 1H NMR, and stopped-flow light scattering. Stopped-flow light scattering was also used to measure the average lifetime of the unpolymerized wormlike micelles. A comparison of the average lifetime of unpolymerized wormlike micelles with the surfactant monomer propagation rate was used to elucidate the mechanism of polymerization. There is a significant correlation between the ratio of the average lifetime to the monomer propagation rate and the average aggregation number of the polymerized wormlike micelles. PMID:16430253

Zhu, Zhiyuan; González, Yamaira I; Xu, Hangxun; Kaler, Eric W; Liu, Shiyong

2006-01-31

68

Multiply Charged Metal Cluster Anions  

SciTech Connect

Formation and stability patterns of silver dianionic and gold trianionic clusters are investigated with Penning-trap experiments and a shell-correction method including shape deformations. The theoretical predictions pertaining to the appearance sizes and electronic shell effects are in remarkable agreement with the experiments. Decay of the multiply anionic clusters occurs predominantly by electron tunneling through a Coulomb barrier rather than via fission, leading to appearance sizes unrelated to those of multiply cationic clusters.

Yannouleas, Constantine; Landman, Uzi; Herlert, Alexander; Schweikhard, Lutz

2001-04-02

69

Multiply charged metal cluster anions.  

PubMed

Formation and stability patterns of silver dianionic and gold trianionic clusters are investigated with Penning-trap experiments and a shell-correction method including shape deformations. The theoretical predictions pertaining to the appearance sizes and electronic shell effects are in remarkable agreement with the experiments. Decay of the multiply anionic clusters occurs predominantly by electron tunneling through a Coulomb barrier rather than via fission, leading to appearance sizes unrelated to those of multiply cationic clusters. PMID:11290091

Yannouleas, C; Landman, U; Herlert, A; Schweikhard, L

2001-04-01

70

Assessing the Development Gap  

Microsoft Academic Search

Current report aims to identify major existing gaps in the four socio-economic dimensions (economic, human, environmental, and institutional) and to reveal those gaps which could potentially hinder social and economic integration of neighbor states with the EU. To achieve this, the authors aim to assess the existing trends in the size of the gaps across countries and problem areas, taking

Alexander Chubrik; Irina Denisova; Vladimir Dubrovskiy; Marina Kartseva; Irina Makenbaeva; Magdalena Rokicka; Irina Sinitsina; Michael Tokmazishvili

2007-01-01

71

Anion composition of aça?? extracts.  

PubMed

Many products labeled aça?? are presently marketed as natural supplements with various claimed health benefits. Authentic aça?? is expensive; as a result, numerous products labeled as containing aça?? are being sold that actually contain little or no aça??. Authentic aça?? samples from Brazil and Florida as well as several reputed aça?? products were analyzed by suppressed conductometric anion chromatography. Columns with different selectivities were used to obtain a complete separation of all anions. Tandem mass spectrometry was used for confirmation of the less common ions. Quinate, lactate, acetate, formate, galacturonate, chloride, sulfate, malate, oxalate, phosphate, citrate, isocitrate, and myo-inositol hexakisphosphate (phytate) were found. Only the Florida aça?? had detectable levels of hexanoate. No aça?? sample had any detectable levels of tartrate, which is present in abundance in grape juice, the most common adulterant. The highly characteristic anion profile and in particular the absence of tartrate can readily be used to identify authentic aça?? products. Aça?? from Florida had a 6 times greater level of phytate. The present analytical approach for phytate may be superior to extant methods. PMID:23772604

Liao, Hongzhu; Shelor, C Phillip; Chen, Yongjing; Sabaa-Srur, Armando U O; Smith, Robert E; Dasgupta, Purnendu K

2013-06-26

72

Competition between monovalent and divalent anions for calcined and uncalcined hydrotalcite: anion exchange and adsorption sites  

Microsoft Academic Search

Hydrotalcite compounds are well-known anion exchangers. Their anionic exchange capacity (A.E.C.) increases with thermal treatment together with their specific surface area and porosity. In the presence of mono- and divalent anions such as Cl?, SO42? and CrO42?, calcined hydrotalcite behaves not only as an anion exchanger but also as an oxide adsorbent. In the case of divalent anions, the adsorbed

L. Châtelet; J. Y. Bottero; J. Yvon; A. Bouchelaghem

1996-01-01

73

From anion receptors to transporters.  

PubMed

Cystic fibrosis is the most well-known of a variety of diseases termed channelopathies, in which the regulation of ion transport across cell membranes is so disrupted that the threshold of a pathology is passed. The human toll exacted by these diseases has led a number of research groups, including our own, to create compounds that mediate ion transport across lipid bilayers. In this Account, we discuss three classes of synthetic compounds that were refined to bind and transport anions across lipid bilayer membranes. All of the compounds were originally designed as anion receptors, that is, species that would simply create stable complexes with anions, but were then further developed as transporters. By studying structurally simple systems and varying their properties to change the degree of preorganization, the affinity for anions, or the lipophilicity, we have begun to rationalize why particular anion transport mechanisms (cotransport or antiport processes) occur in particular cases. For example, we have studied the chloride transport properties of receptors based on the closely related structures of isophthalamide and pyridine-2,6-dicarboxamide: the central ring in each case was augmented with pendant methylimidazole groups designed to cotransport H(+) and Cl(-). We observed that the more preorganized pyridine-based receptor was the more efficient transporter, a finding replicated with a series of isophthalamides in which one contained hydroxyl groups designed to preorganize the receptor. This latter class of compound, together with the natural product prodigiosin, can transport bicarbonate (as part of a chloride/bicarbonate antiport process) across lipid bilayer membranes. We have also studied the membrane transport properties of calix[4]pyrroles. Although the parent meso-octamethylcalix[4]pyrrole functions solely as a Cs(+)/Cl(-) cotransporter, other compounds with increased anion affinities can function through an antiport process. One example is octafluoro-meso-octamethylcalix[4]pyrrole; with its electron-withdrawing substituents, it can operate through a chloride/bicarbonate antiport process. Moreover, calix[4]pyrroles with additional hydrogen bond donors can operate through a chloride/nitrate antiport process. Thus, increasing the affinity of the receptor in these cases allows the compound to transport an anion in the absence of a cation. Finally, we have studied the transport properties of simple thioureas and shown that these compounds are highly potent chloride/bicarbonate antiport agents that function at low concentrations. In contrast, the urea analogues are inactive. The higher hydrophobicity (reflected in higher values for the logarithm of the water-octanol partition constant, or log P) and lower polar surface areas of the thiourea compounds compared to their urea analogues may provide a clue to the high potency of these compounds. This observation might serve as a basis for designing future small-molecule transporters. PMID:21207951

Gale, Philip A

2011-03-15

74

Functionalized anion exchange stationary phase for separation of anionic compounds.  

PubMed

Synthesis of the multilayered stationary phases containing quaternary ammonium functional groups on the silica support was described. Bonded phases were characterized by elemental analysis, solid state (13)C NMR spectroscopy and chromatographic methods. The surface of silica support was coated with different number of polymeric layers formed by condensation polymerization of primary amine (methylamine) with diepoxide (1,4-butanedioldiglycidyl ether). A series of stationary phases with different number of polymerized layers were tested. Separation of an inorganic anions sample (F(-), Cl(-), NO2(-), Br(-), NO3(-)) and nucleotides was performed. PMID:24913867

Bocian, Szymon; Studzi?ska, Sylwia; Buszewski, Bogus?aw

2014-09-01

75

The gap gene network  

PubMed Central

Gap genes are involved in segment determination during the early development of the fruit fly Drosophila melanogaster as well as in other insects. This review attempts to synthesize the current knowledge of the gap gene network through a comprehensive survey of the experimental literature. I focus on genetic and molecular evidence, which provides us with an almost-complete picture of the regulatory interactions responsible for trunk gap gene expression. I discuss the regulatory mechanisms involved, and highlight the remaining ambiguities and gaps in the evidence. This is followed by a brief discussion of molecular regulatory mechanisms for transcriptional regulation, as well as precision and size-regulation provided by the system. Finally, I discuss evidence on the evolution of gap gene expression from species other than Drosophila. My survey concludes that studies of the gap gene system continue to reveal interesting and important new insights into the role of gene regulatory networks in development and evolution. PMID:20927566

2010-01-01

76

GapZappers  

NSDL National Science Digital Library

In this online Flash activity students use their knowledge of addition of fractions and equivalent forms to navigate 15 levels of play. Each level progresses in difficulty and includes gaps measured in meters that students must fill in using fractional pieces to enable the lizard to move on in the field of play. Once the gap is filled, check the gap and the lizard will move on showing the fractional equation that solved the problem.

King, Colleen

2013-01-01

77

Adsorption affinity of anions on metal oxyhydroxides  

NASA Astrophysics Data System (ADS)

The dependences of anion (phosphate, carbonate, sulfate, chromate, oxalate, tartrate, and citrate) adsorption affinity anions from geometric characteristics, acid-base properties, and complex forming ability are generalized. It is shown that adsorption depends on the nature of both the anions and the ionic medium and adsorbent. It is established that anions are generally grouped into the following series of adsorption affinity reduction: PO{4/3-}, CO{3/2-} > C2O{4/2-}, C(OH)(CH2)2(COO){3/3-}, (CHOH)2(COO){2/2-} > CrO{4/2-} ? SO{4/2-}.

Pechenyuk, S. I.; Semushina, Yu. P.; Kuz'mich, L. F.

2013-03-01

78

(Parallel GAP) A GAP4 Package  

E-print Network

) . . . . . . . 16 1.10 Modifying the GAP kernel . . . . 17 2 Slave Listener 18 2.1 Slave Listener CommandsSemiEchelonMatrix) . . . 39 5.6 Caching slave task outputs (ParSemiEchelonMat revisited) . . 42 5.7 Agglomerating tasks

Cooperman, Gene

79

Organic anion transporter (Slc22a) family members as mediators of toxicity  

SciTech Connect

Exposure of the body to toxic organic anions is unavoidable and occurs from both intentional and unintentional sources. Many hormones, neurotransmitters, and waste products of cellular metabolism, or their metabolites, are organic anions. The same is true for a wide variety of medications, herbicides, pesticides, plant and animal toxins, and industrial chemicals and solvents. Rapid and efficient elimination of these substances is often the body's best defense for limiting both systemic exposure and the duration of their pharmacological or toxicological effects. For organic anions, active transepithelial transport across the renal proximal tubule followed by elimination via the urine is a major pathway in this detoxification process. Accordingly, a large number of organic anion transport proteins belonging to several different gene families have been identified and found to be expressed in the proximal nephron. The function of these transporters, in combination with the high volume of renal blood flow, predisposes the kidney to increased toxic susceptibility. Understanding how the kidney mediates the transport of organic anions is integral to achieving desired therapeutic outcomes in response to drug interactions and chemical exposures, to understanding the progression of some disease states, and to predicting the influence of genetic variation upon these processes. This review will focus on the organic anion transporter (OAT) family and discuss the known members, their mechanisms of action, subcellular localization, and current evidence implicating their function as a determinant of the toxicity of certain endogenous and xenobiotic agents.

Sweet, Douglas H. [Department of Pharmaceutical Sciences, Medical University of South Carolina, 280 Calhoun Street (Room QE218), PO Box 250140, Charleston, SC 29425 (United States)]. E-mail: sweetd@musc.edu

2005-05-01

80

Photodissociation of nitromethane cluster anions  

SciTech Connect

Three types of anionic fragments are observed in the photodissociation of nitromethane cluster anions, (CH{sub 3}NO{sub 2}){sub n}{sup -}, n=1-6, at 355 nm: NO{sub 2}{sup -}(CH{sub 3}NO{sub 2}){sub k}, (CH{sub 3}NO{sub 2}){sub k}{sup -}, and OH{sup -} (kanion core, CH{sub 3}NO{sub 2}{sup -}, solvated by n-1 neutral nitromethane molecules. The NO{sub 2}{sup -}(CH{sub 3}NO{sub 2}){sub k} and OH{sup -} fragments formed from these clusters are described as core-dissociation products, while the (CH{sub 3}NO{sub 2}){sub k}{sup -} fragments are attributed to energy transfer from excited CH{sub 3}NO{sub 2}{sup -} into the solvent network or a core-dissociation--recombination (caging) mechanism. As with other cluster families, the fraction of caged photofragments shows an overall increase with increasing cluster size. The low-lying A{sup 2}A{sup '} and/or B{sup 2}A{sup '} electronic states of CH{sub 3}NO{sub 2}{sup -} are believed responsible for photoabsorption leading to dissociation to NO{sub 2}{sup -} based fragments, while the C{sup 2}A{sup ''} state is a candidate for the OH{sup -} pathway. Compared to neutral nitromethane, the photodissociation of CH{sub 3}NO{sub 2}{sup -} requires lower energy photons because the photochemically active electron occupies a high energy {pi}{sup *} orbital (which is vacant in the neutral). Although the electronic states in the photodissociation of CH{sub 3}NO{sub 2} and CH{sub 3}NO{sub 2}{sup -} are different, the major fragments, CH{sub 3}+NO{sub 2} and CH{sub 3}+NO{sub 2}{sup -}, respectively, both form via C-N bond cleavage.

Goebbert, Daniel J.; Khuseynov, Dmitry; Sanov, Andrei [Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 84721-0041 (United States)

2010-08-28

81

Confronting the Achievement Gap  

ERIC Educational Resources Information Center

This article talks about the large achievement gap between children of color and their white peers. The reasons for the achievement gap are varied. First, many urban minorities come from a background of poverty. One of the detrimental effects of growing up in poverty is receiving inadequate nourishment at a time when bodies and brains are rapidly…

Gardner, David

2007-01-01

82

Advanced rapidity gap trigger  

E-print Network

Nubmer of phisically interesting processes is charachterized by the rapidity gaps. In reality, this gaps is filled by uderlying events with high (more than 0.75 for higgs) probability. In this paper we purpose a way to detect this shadowed events with aim to raise the number of rare events.

Abramovsky, V A

2004-01-01

83

Bridging the spirituality gap  

Microsoft Academic Search

An identifiable 'spirituality gap' exists between the lived experience of mental health difficulties, frequently spoken of in spiritual terms, and the professional expertise of mental health practitioners from whom we might seek help. This paper contrasts the lived experience of suicidality with the academic and professional discipline of suicidology to show that this gap arises from a scientific commitment to

David Webb

2005-01-01

84

Organic anion-transporting polypeptides.  

PubMed

Organic anion-transporting polypeptides or OATPs are central transporters in the disposition of drugs and other xenobiotics. In addition, they mediate transport of a wide variety of endogenous substrates. The critical role of OATPs in drug disposition has spurred research both in academia and in the pharmaceutical industry. Translational aspects with clinical questions are the focus in academia, while the pharmaceutical industry tries to define and understand the role these transporters play in pharmacotherapy. The present overview summarizes our knowledge on the interaction of food constituents with OATPs and on the OATP transport mechanisms. Further, it gives an update on the available information on the structure-function relationship of the OATPs and, finally, covers the transcriptional and posttranscriptional regulation of OATPs. PMID:24745984

Stieger, Bruno; Hagenbuch, Bruno

2014-01-01

85

Photoelectron Spectroscopy of Benzoquinonide and Dehydrobenzoquinone Anions  

E-print Network

photoelectron spectra of the dehydrobenzoquinone (1·-) and benzoquinonide (2-) anions are reported. For 1 or characterized. In this paper we report the photoelectron spectra of dehy- drobenzoquinone anion (1 value for the EA of 2 has been obtained. To help in the interpretation of the photoelectron spectra

Lineberger, W. Carl

86

Hydrogen in anion vacancies of semiconductors  

NASA Astrophysics Data System (ADS)

Hydrogen typically terminates the dangling bonds around vacancies in semiconductors, thereby, partially or completely passivating the vacancies. However, it has been shown recently that hydrogen in anion vacancies of many semiconductors, such as ZnO, MgO, InN, SnO2, and GaN, takes multi-coordinated structures and acts as shallow donors, providing n-type conductivity to the materials. We study the hydrogen in the anion vacancies of a series of II-VI and III-V semiconductors using density functional calculations. The results on these materials show that, in the anion vacancies of polar II-VI semiconductors, the hydrogen is usually anionic and is coordinated with more than one cation atoms as a result of the relatively high ionicity of the host materials. The hydrogen coordination number depends on the host anion size. On the other hand, in more covalent semiconductors such as some III-V semiconductors, the single cation-H bonding configuration may become most stable. In the anion vacancies of ZnX and CdX where X represents anions, hydrogen is typically amphoteric except for oxides, in which the small anion size prohibits the formation of the cation-cation bond that is required for the acceptor configuration.

Du, Mao-Hua; Singh, David

2009-03-01

87

Tripodal Receptors for Cation and Anion Sensors  

PubMed Central

This review discusses different types of artificial tripodal receptors for the selective recognition and sensing of cations and anions. Examples on the relationship between structure and selectivity towards cations and anions are described. Furthermore, their applications as potentiometric ion sensing are emphasised, along with their potential applications in optical sensors or optodes.

Kuswandi, Bambang; Nuriman; Verboom, Willem; Reinhoudt, David N.

2006-01-01

88

Covalent Polymers Containing Discrete Heterocyclic Anion Receptors  

PubMed Central

This chapter covers recent advances in the development of polymeric materials containing discrete heterocyclic anion receptors, and focuses on advances in anion binding and chemosensor chemistry. The development of polymers specific for anionic species is a relatively new and flourishing area of materials chemistry. The incorporation of heterocyclic receptors capable of complexing anions through non-covalent interactions (e.g., hydrogen bonding and electrostatic interactions) provides a route to not only sensitive but also selective polymer materials. Furthermore, these systems have been utilized in the development of polymers capable of extracting anionic species from aqueous environments. These latter materials may lead to advances in water purification and treatment of diseases resulting from surplus ions. PMID:20871791

Rambo, Brett M.; Silver, Eric S.; Bielawski, Christopher W.; Sessler, Jonathan L.

2010-01-01

89

21. Newfound Gap Road, last pullout before gap, North Carolina ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

21. Newfound Gap Road, last pullout before gap, North Carolina side. - Great Smoky Mountains National Park Roads & Bridges, Newfound Gap Road, Between Gatlinburg, TN & Cherokee, NC, Gatlinburg, Sevier County, TN

90

Metabolic Syndrome  

MedlinePLUS

... metabolic syndrome fact sheet hOW is the metAbOlic syndrOme treAted? Increasing physical activity and losing weight are the best ways to begin to manage your condition. Medications can also treat risk factors such as ... factors for the metabolic syndrome, talk with your doctor. Your doctor can run ...

91

Generation gaps in engineering?  

E-print Network

There is much enthusiastic debate on the topic of generation gaps in the workplace today; what the generational differences are, how to address the apparent challenges, and if the generations themselves are even real. ...

Kim, David J. (David Jinwoo)

2008-01-01

92

Generation of superoxide anion radicals and platelet glutathione peroxidase activity in patients with schizophrenia  

PubMed Central

Blood platelets are considered to be a peripheral marker in schizophrenia and other psychiatric disorders. Oxidative stress in schizophrenia may be responsible for changes in platelet metabolism and function; therefore, the aim of this study was to examine and compare the generation of superoxide anions and activity of an antioxidant enzyme (glutathione peroxidase [GPx]) in blood platelets in patients with schizophrenia and healthy subjects. The level of superoxide anions generated in platelets after thrombin and platelet-activating factor stimulation and activity of GPx in patients with schizophrenia and healthy volunteers was estimated. The results obtained from the study indicate that the generation of superoxide anions in platelets as a response of platelets in patients with schizophrenia to such activating factors as thrombin or platelet-activating factor is higher than in the response of platelets of healthy subjects. In platelets from schizophrenic patients, suppressed GPx activity of about 67% was observed. PMID:24833903

Dietrich-Muszalska, Anna; Kwiatkowska, Anna

2014-01-01

93

Inception report and Gap analysis  

E-print Network

Inception report and Gap analysis Boiler inspection Riga, June 2004 #12;Inception report and gap analysis ­ boiler inspection Table of Content 1 INTRODUCTION ................................................................................................................................. 3 2 BOILER INSTALLATIONS ­ GAP ANALYSIS

94

SOUTHWEST REGIONAL GAP LAND COVER  

EPA Science Inventory

The Gap Analysis Program is a national inter-agency program that maps the distribution of plant communities and selected animal species and compares these distributions with land stewardship to identify gaps in biodiversity protection. GAP uses remote satellite imag...

95

Resonant neutralization of hydrogen anions near the Be(0001) surface  

NASA Astrophysics Data System (ADS)

The resonant charge transfer interaction between atomic ions and metal surfaces is a tool to examine the surface electronic structure and its associated implications to the surface chemistry. Using a Crank-Nicholson propagation technique we simulate and visualize the dynamical electron distribution during a charge transfer reaction of a hydrogen anion with a plane Be (0001) surface. The time-dependent information as the ion evolves, that is, as it decays and captures, is obtained and the final ion survival probability is determined. Comparisons with previous results involving Cu and Pd surfaces [1] uncover the dependence of the ion survival on the size, position and detailed structure of the surface electronic band gap. [1] Chakraborty et al., Nucl. Instrum. Meth. B 241, 43 (2005)

Brown, Nathan; Chakraborty, Himadri; Thumm, Uwe

2008-05-01

96

There Are GAPS and There Are GAPS  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Guanine nucleotide-binding proteins (G proteins) transduce a very large number of cellular regulatory signals. Several recent papers have shown that the larger heterotrimeric G proteins are regulated by a class of molecules known as the RGS proteins (regulators of G protein-signaling family) that are analogous to the GAPs (GTPase activating proteins), which regulate small monomeric G proteins. Iyengar summarizes this evidence and discusses the mechanism of action of the RGS proteins.

Ravi Iyengar (Mount Sinai School of Medicine;Department of Pharmacology)

1997-01-03

97

Supramolecular electron transfer by anion binding.  

PubMed

Anion binding has emerged as an attractive strategy to construct supramolecular electron donor-acceptor complexes. In recent years, the level of sophistication in the design of these systems has advanced to the point where it is possible to create ensembles that mimic key aspects of the photoinduced electron-transfer events operative in the photosynthetic reaction centre. Although anion binding is a reversible process, kinetic studies on anion binding and dissociation processes, as well as photoinduced electron-transfer and back electron-transfer reactions in supramolecular electron donor-acceptor complexes formed by anion binding, have revealed that photoinduced electron transfer and back electron transfer occur at time scales much faster than those associated with anion binding and dissociation. This difference in rates ensures that the linkage between electron donor and acceptor moieties is maintained over the course of most forward and back electron-transfer processes. A particular example of this principle is illustrated by electron-transfer ensembles based on tetrathiafulvalene calix[4]pyrroles (TTF-C4Ps). In these ensembles, the TTF-C4Ps act as donors, transferring electrons to various electron acceptors after anion binding. Competition with non-redox active substrates is also observed. Anion binding to the pyrrole amine groups of an oxoporphyrinogen unit within various supramolecular complexes formed with fullerenes also results in acceleration of the photoinduced electron-transfer process but deceleration of the back electron transfer; again, this is ascribed to favourable structural and electronic changes. Anion binding also plays a role in stabilizing supramolecular complexes between sulphonated tetraphenylporphyrin anions ([MTPPS](4-): M = H(2) and Zn) and a lithium ion encapsulated C(60) (Li(+)@C(60)); the resulting ensemble produces long-lived charge-separated states upon photoexcitation of the porphyrins. PMID:22766725

Fukuzumi, Shunichi; Ohkubo, Kei; D'Souza, Francis; Sessler, Jonathan L

2012-10-11

98

Development of an In Silico Metabolic Simulator and Searchable Metabolism Database for Chemical Risk Assessments  

EPA Science Inventory

The US EPA is faced with long lists of chemicals that need to be assessed for hazard, and a gap in evaluating chemical risk is accounting for metabolic activation resulting in increased toxicity. The goals of this project are to develop a capability to predict metabolic maps of x...

99

Serologically-Related Anionic Peroxidases from Petunia and Cucumber can Substitute Flavonoid Antioxidants  

Microsoft Academic Search

In this study we have investigated whether naturally occurring flavonoid-deficient mutant Red Star of Petunia hybrida is capable of metabolizing H2O2 by invoking other antioxidant enzyme system. We demonstrated that reduced flower pigmentation due to a reduction in the chalcone synthase mRNA expression results in strong H2O2 accumulation accompanied by the induction of a specific set of anionic peroxidase (PRX),

V. Repka; I. Fischerová

2000-01-01

100

Effect of nickel deficiency on soluble anion, amino acid, and nitrogen levels in barley  

Microsoft Academic Search

Barley (Hordeum vulgare L. cv. ‘Onda’) plants were grown in nutrient solutions supplied either 0 (no Ni added), 0.6, or 1.0 ?M NiSO4. Plants supplied 0 ?M Ni developed Ni deficiency symptoms; Ni deficiency resulted in the disruption of nitrogen metabolism, and affected the concentration\\u000a of malate and various inorganic anions in roots, shoots, and grain of barley.\\u000a \\u000a The concentrations

Patrick H. Brown; Ross M. Welch; James T. Madison

1990-01-01

101

Characterization of Antisense Transformed Plants Deficient in the Tobacco Anionic Peroxidase.  

PubMed Central

On the basis of the biological compounds that they metabolize, plant peroxidases have long been implicated in plant growth, cell wall biogenesis, lignification, and host defenses. Transgenic tobacco (Nicotiana tabacum L.) plants that underexpress anionic peroxidase were generated using antisense RNA. The antisense RNA was found to be specific for the anionic isoenzyme and highly effective, reducing endogenous transcript levels and total peroxidase activity by as much as 1600-fold. Antisense-transformed plants appeared normal at initial observation; however, growth studies showed that plants with reduced peroxidase activity grow taller and flower sooner than control plants. In contrast, previously transformed plants overproducing anionic peroxidase were shorter and flowered later than controls. Axillary buds were more developed in antisense-transformed plants and less developed in plants overproducing this enzyme. It was found that the lignin content in leaf, stem, and root was unchanged in antisense-transformed plants, which does not support a role for anionic peroxidase in the lignification of secondary xylem vessels. However, studies of wounded tissue show some reduction in wound-induced deposition of lignin-like polymers. The data support a possible role for tobacco anionic peroxidase in host defenses but not without a reduction in growth potential. PMID:12223765

Lagrimini, L. M.; Gingas, V.; Finger, F.; Rothstein, S.; Liu, TTY.

1997-01-01

102

Spectral Gap Amplification  

E-print Network

A large number of problems in science can be solved by preparing a specific eigenstate of some Hamiltonian H. The generic cost of quantum algorithms for these problems is determined by the inverse spectral gap of H for that eigenstate and the cost of evolving with H for some fixed time. The goal of spectral gap amplification is to construct a Hamiltonian H' with the same eigenstate as H but a bigger spectral gap, requiring that constant-time evolutions with H' and H are implemented with nearly the same cost. We show that a quadratic spectral gap amplification is possible when H satisfies a frustration-free property and give H' for these cases. This results in quantum speedups for optimization problems. It also yields improved constructions for adiabatic simulations of quantum circuits and for the preparation of projected entangled pair states (PEPS), which play an important role in quantum many-body physics. Defining a suitable black-box model, we establish that the quadratic amplification is optimal for frustration-free Hamiltonians and that no spectral gap amplification is possible, in general, if the frustration-free property is removed. A corollary is that finding a similarity transformation between a stoquastic Hamiltonian and the corresponding stochastic matrix is hard in the black-box model, setting limits to the power of some classical methods that simulate quantum adiabatic evolutions.

Rolando D. Somma; Sergio Boixo

2011-10-11

103

Ditopic ambiphilicity of an anionic dimetalloborylene complex.  

PubMed

In early reports, the boron atom of the anionic borido complexes [{(?(5)-C(5)H(4)R)(OC)(2)Mn}(2)B](-) (R = H, Me) showed nucleophilic behavior in the presence of electrophiles such as methyl iodide and group 11 metal chlorides, akin to the ground-breaking boryl lithium of Yamashita and Nozaki. Later, a reaction with the well-known transition metal Lewis base [Pt(PCy(3))(2)] suggested the possibility of boron-centered electrophilicity. In this paper we elucidate a third reactivity profile of the anion, nucleophilic substitution on heavier halides of group 14 metals by a manganese center. Meanwhile, other group 11 halides were found to interact with the boron center, but form structures different from those seen with gold. The basis of the discrimination of the anion between main group and transition metal halides is explored computationally, and the ditopic, ambiphilic reactivity of the anions is discussed. PMID:23331127

Braunschweig, Holger; Damme, Alexander; Dewhurst, Rian D; Kramer, Thomas; Östreicher, Sebastian; Radacki, Krzysztof; Vargas, Alfredo

2013-02-13

104

Dual Transport Properties of Anion Exchanger 1  

PubMed Central

Previous results suggested that specific point mutations in human anion exchanger 1 (AE1) convert the electroneutral anion exchanger into a monovalent cation conductance. In the present study, the transport site for anion exchange and for the cation leak has been studied by cysteine scanning mutagenesis and sulfhydryl reagent chemistry. Moreover, the role of some highly conserved amino acids within members of the SLC4 family to which AE1 belongs has been assessed in AE1 transport properties. The results suggest that the same transport site within the AE1 spanning domain is involved in anion exchange or in cation transport. A functioning mechanism for this transport site is proposed according to transport properties of the different studied point mutations of AE1. PMID:21257764

Barneaud-Rocca, Damien; Borgese, Franck; Guizouarn, Helene

2011-01-01

105

Structure of the human voltage-dependent anion channel.  

PubMed

The voltage-dependent anion channel (VDAC), also known as mitochondrial porin, is the most abundant protein in the mitochondrial outer membrane (MOM). VDAC is the channel known to guide the metabolic flux across the MOM and plays a key role in mitochondrially induced apoptosis. Here, we present the 3D structure of human VDAC1, which was solved conjointly by NMR spectroscopy and x-ray crystallography. Human VDAC1 (hVDAC1) adopts a beta-barrel architecture composed of 19 beta-strands with an alpha-helix located horizontally midway within the pore. Bioinformatic analysis indicates that this channel architecture is common to all VDAC proteins and is adopted by the general import pore TOM40 of mammals, which is also located in the MOM. PMID:18832158

Bayrhuber, Monika; Meins, Thomas; Habeck, Michael; Becker, Stefan; Giller, Karin; Villinger, Saskia; Vonrhein, Clemens; Griesinger, Christian; Zweckstetter, Markus; Zeth, Kornelius

2008-10-01

106

The superfamily of organic anion transporting polypeptides  

Microsoft Academic Search

Organic anion transporting polypeptides (Oatps\\/OATPs) form a growing gene superfamily and mediate transport of a wide spectrum of amphipathic organic solutes. Different Oatps\\/OATPs have partially overlapping and partially distinct substrate preferences for organic solutes such as bile salts, steroid conjugates, thyroid hormones, anionic oligopeptides, drugs, toxins and other xenobiotics. While some Oatps\\/OATPs are preferentially or even selectively expressed in one

B Hagenbuch; P. J Meier

2003-01-01

107

A new class of organocatalysts: sulfenate anions.  

PubMed

Sulfenate anions are known to act as highly reactive species in the organic arena. Now they premiere as organocatalysts. Proof of concept is offered by the sulfoxide/sulfenate-catalyzed (1-10?mol%) coupling of benzyl halides in the presence of base to generate trans-stilbenes in good to excellent yields (up to 99%). Mechanistic studies support the intermediacy of sulfenate anions, and the deprotonated sulfoxide was determined to be the resting state of the catalyst. PMID:25111259

Zhang, Mengnan; Jia, Tiezheng; Yin, Haolin; Carroll, Patrick J; Schelter, Eric J; Walsh, Patrick J

2014-09-26

108

Metabolic myopathies  

NASA Technical Reports Server (NTRS)

Metabolic myopathies are disorders of muscle energy production that result in skeletal muscle dysfunction. Cardiac and systemic metabolic dysfunction may coexist. Symptoms are often intermittent and provoked by exercise or changes in supply of lipid and carbohydrate fuels. Specific disorders of lipid and carbohydrate metabolism in muscle are reviewed. Evaluation often requires provocative exercise testing. These tests may include ischemic forearm exercise, aerobic cycle exercise, and 31P magnetic resonance spectroscopy with exercise.

Martin, A.; Haller, R. G.; Barohn, R.; Blomqvist, C. G. (Principal Investigator)

1994-01-01

109

Uncertainties in Gapped Graphene  

E-print Network

Motivated by graphene-based quantum computer we examine the time-dependence of the position-momentum and position-velocity uncertainties in the monolayer gapped graphene. The effect of the energy gap to the uncertainties is shown to appear via the Compton-like wavelength $\\lambda_c$. The uncertainties in the graphene are mainly contributed by two phenomena, spreading and zitterbewegung. While the former determines the uncertainties in the long-range of time, the latter gives the highly oscillation to the uncertainties in the short-range of time. The uncertainties in the graphene are compared with the corresponding values for the usual free Hamiltonian $\\hat{H}_{free} = (p_1^2 + p_2^2) / 2 M$. It is shown that the uncertainties can be under control within the quantum mechanical law if one can choose the gap parameter $\\lambda_c$ freely.

Eylee Jung; Kwang S. Kim; DaeKil Park

2011-07-27

110

Anion exchange properties of a mesoporous aluminophosphate  

SciTech Connect

A mesoporous aluminophosphate support, meso-AlPO, was synthesized by phosphate treatment of an AlO{sub 4}Al{sub 12}(OH){sub 24}(H{sub 2}O){sup 7+} cluster/dodecyl sulfate salt, followed by extraction of the surfactant with an acetate/methanol solution. The meso-AlPO product was shown to be an effective anion exchange material. Anion exchange capacities for chromate and several monoanionic and dianionic organic dyes fell in the range from approximately 1.3--1.6 meq/g. Control experiments with the neutral support MCM-41 and a nonionic dye indicated that anion adsorption in meso-AlPO was caused predominantly by electrostatic interactions rather than pure physisorption. Multiple exchanges were possible if the support was regenerated by acid treatment at pH 4.3. While the material exhibited size-selectivity for anionic dyes, the average pore sizes increased during anion exchanges in aqueous solutions. The mesopore structure of meso-AlPO was thermally stable up to 200 C, and anion exchanges at 100 C under aqueous reflux resulted in similar exchange capacities as room-temperature exchanges.

Kron, D.A.; Holland, B.T.; Wipson, R.; Maleke, C.; Stein, A.

1999-11-09

111

Systems genetics of mineral metabolism.  

PubMed

Minerals are essential and toxic elements that have an impact on human health. Although we have learned a tremendous amount about the metabolism, biological roles, and health effects of minerals with the tools of biochemistry, cell biology, and molecular genetics, there are gaps in our knowledge of mineral biology that will benefit from new approaches. Forward genetics, whereby variations in phenotypes are mapped to natural genetic variation in the genome, has been successfully used to increase our understanding of many biologically important traits but has not yet been used extensively for mineral metabolism. In addition, the well-appreciated existence of interactions between minerals justifies a broader, systems approach to the study of mineral metabolism, i.e., ionomics. This short review will explain the value of forward genetics and ionomics as tools for exploring mammalian mineral metabolism. PMID:21270371

Fleet, James C; Replogle, Rebecca; Salt, David E

2011-03-01

112

[Acid-base homeostasis: metabolic acidosis and metabolic alkalosis].  

PubMed

Acid-base homeostasis ensured by the kidneys, which maintain the equilibrium between proton generation by cellular metabolism and proton excretion in urine. This requirement is lifesaving because of the protons' ability to bind to anionic proteins in the extracellular space, modifying their structure and functions. The kidneys also regenerate bicarbonates. The kidney is not the sole organ in charge of maintaining blood pH in a very narrow range; lungs are also involved since they allow a large amount of volatile acid generated by cellular respiration to be eliminated. PMID:24993393

Dussol, Bertrand

2014-07-01

113

Skills Gaps in Australian Firms  

ERIC Educational Resources Information Center

This paper reports the results of a survey of more than 2000 managers examining perceptions of skills gaps in a range of Australian firms. It finds that three quarters report a skills gap, and almost one third report skills gaps across the whole organisation. Firm size and industry differences exist in perceptions of the effect of the skills gap…

Lindorff, Margaret

2011-01-01

114

Differential phosphorylation of the gap junction protein connexin43 in junctional communication-competent and -deficient cell lines  

Microsoft Academic Search

Connexin43 is a member of the highly ho- mologous connexin family of gap junction proteins. We have studied how connexin monomers are assem- bled into functional gap junction plaques by examining the biosynthesis of connexin43 in cell types that differ greatly in their ability to form functional gap junc- tions. Using a combination of metabolic radiolabeling and immunoprecipitation, we have

Linda S. Musil; Bruce A. Cunningham; Gerald M. Edelman; Daniel A. Goodenough

1990-01-01

115

Determination of Anion Ordering in Mixed Apatites via Multinuclear Solid-State NMR & X-ray Crystallography  

NASA Astrophysics Data System (ADS)

Subtle changes in crystallographic anion position in apatite sensu latu Ca5(PO4)3(F,OH,Cl) are known to affect greatly its macroscopic physical properties, such as acid resistivity and hardness. While the anion positions in endmember compositions are well described, there exist substantial gaps in our understanding of anion ordering in mixed binary and ternary compositions because of potential steric anion interactions and symmetry changes. X-ray diffraction analysis of these binary/ternary mixtures is well-suited to address the atomic positions and average occupancies of these anion sites for well-ordered systems. Multinuclear solid-state NMR methods complement XRD structure studies if there exist column ordering reversals or disorder in the atomic positions of the anions, as NMR is sensitive to the atomic arrangement within short distances of the nucleus (<4Å). Using these analytical techniques the anion ordering along the F-Cl solid-solution join is reported, and features an off-mirror fluorine site at (0,0,0.167). The migration of fluorine away from its end-member site within the {00l} mirror plane and subsequent migration of chlorine in the opposing direction results in acceptable F-Cl distances in the anion column. Exceptionally low H content in the anion channel was afforded via high-temperature (1200°C) solid-state reaction under vacuum. The speciation of H was determined by 1H{31P} REDOR experiments, from which the REDOR difference spectrum features a single resonance at ?H = 1.6 ppm which can be assigned to OH groups. The abundance of OH was confirmed by comparison of single-pulse (SP) 31P and cross-polarization 31P{1H} NMR (CP) spectral intensities to those of a crystalline synthetic hydroxylapatite, and showed that only 0.4 mol% of the 31P in the composition occurs in hydroxylapatite-like configurations.

Vaughn, J. S.; Phillips, B. L.; Hughes, J. M.; Nekvasil, H.; Ustunisik, G. K.; Lindsley, D. H.; Coraor, A. E.; McCubbin, F. M.; Woerner, W. R.

2013-12-01

116

GAP Program Overview  

NASA Technical Reports Server (NTRS)

NASA's General Aviation Propulsion (GAP) program is a cooperative program between government and industry. NASA's strategic direction is described by the "Three Pillars" and their Objectives as set forth by NASA Administrator Daniel S. Goldin. NASA's Three Pillars are: 1) Global Civil Aviation, 2) Revolutionary Technology Leaps, and 3) Access To Space.

Burkardt, Leo

1999-01-01

117

STEMMING the Gap  

ERIC Educational Resources Information Center

America has a gap when it comes to youth pursuing science and technology careers. In an effort to improve the knowledge and application of science, technology, engineering, and math (STEM), after-school programs can work in conjunction with formal in-school curriculum to improve science education. One organization that actively addresses this…

Kahler, Jim; Valentine, Nancy

2011-01-01

118

Closing the Performance Gap.  

ERIC Educational Resources Information Center

Describes how the principal of a K-2, 400-student suburban elementary school near Flint, Michigan, worked with her staff and superintendent to develop and implement a strategic plan to close the student achievement gap. Reports significant improvement in reading and math scores after 1 year. (PKP)

Riggins, Cheryl G.

2002-01-01

119

Seismic gaps and earthquakes  

Microsoft Academic Search

McCann et al. [1979] published a widely cited ``seismic gap'' model ascribing earthquake potential categories to 125 zones surrounding the Pacific Rim. Nishenko [1991] published an updated and revised version including probability estimates of characteristic earthquakes with specified magnitudes within each zone. These forecasts are now more than 20 and 10 years old, respectively, and sufficient data now exist to

Yufang Rong; David D. Jackson; Yan Y. Kagan

2003-01-01

120

Seismic gaps and earthquakes  

Microsoft Academic Search

McCann et al. [1979] published a widely cited “seismic gap” model ascribing earthquake potential categories to 125 zones surrounding the Pacific Rim. Nishenko [1991] published an updated and revised version including probability estimates of characteristic earthquakes with specified magnitudes within each zone. These forecasts are now more than 20 and 10 years old, respectively, and sufficient data now exist to

Yufang Rong; David D. Jackson; Yan Y. Kagan

2003-01-01

121

The Salary Gap.  

ERIC Educational Resources Information Center

The growing movement to privatize school management is a reason for comparing compensation and responsibilities in the private and public sectors. Despite the enormous salary gaps, public outrage over superintendents' salaries is common. Sensitive taxpayers might favor superintendent contracts including pay-for-performance factors resembling those…

Bushweller, Kevin

1994-01-01

122

GAP TESTS; COMPARISON BETWEEN UN GAP TEST AND CARD GAP TEST  

E-print Network

98-36 GAP TESTS; COMPARISON BETWEEN UN GAP TEST AND CARD GAP TEST by R. BRANKA and C. MICHOT, FRANCE (tel.: 33 3 44 55 65 19, fax: 33 3 44 55 65 10) ABSTRACT: UN gap test, type 1(a) or 2(a), is the recommended test in the acceptance procedure for transport of explosives in class 1. Up to the revision

Paris-Sud XI, Université de

123

Studies of anions sorption on natural zeolites.  

PubMed

This work presents results of FT-IR spectroscopic studies of anions-chromate, phosphate and arsenate - sorbed from aqueous solutions (different concentrations of anions) on zeolites. The sorption has been conducted on natural zeolites from different structural groups, i.e. chabazite, mordenite, ferrierite and clinoptilolite. The Na-forms of sorbents were exchanged with hexadecyltrimethylammonium cations (HDTMA(+)) and organo-zeolites were obtained. External cation exchange capacities (ECEC) of organo-zeolites were measured. Their values are 17mmol/100g for chabazite, 4mmol/100g for mordenite and ferrierite and 10mmol/100g for clinoptilolite. The used initial inputs of HDTMA correspond to 100% and 200% ECEC of the minerals. Organo-modificated sorbents were subsequently used for immobilization of mentioned anions. It was proven that aforementioned anions' sorption causes changes in IR spectra of the HDTMA-zeolites. These alterations are dependent on the kind of anions that were sorbed. In all cases, variations are due to bands corresponding to the characteristic Si-O(Si,Al) vibrations (occurring in alumino- and silicooxygen tetrahedra building spatial framework of zeolites). Alkylammonium surfactant vibrations have also been observed. Systematic changes in the spectra connected with the anion concentration in the initial solution have been revealed. The amounts of sorbed CrO4(2-), AsO4(3-) and PO4(3-) ions were calculated from the difference between their concentrations in solutions before (initial concentration) and after (equilibrium concentration) sorption experiments. Concentrations of anions were determined by spectrophotometric method. PMID:25002191

Barczyk, K; Mozgawa, W; Król, M

2014-12-10

124

Anion receptor chemistry: highlights from 2008 and 2009.  

PubMed

This critical review covers advances in anion complexation in the year 2008 and 2009. The review discusses anion receptors that employ hydrogen bond donors (both NH and CH), electrostatic interactions, Lewis acidic centres and combinations of these three types of binding interaction to complex anions. Additionally nanotechnological approaches to anion sensing in aqueous solution, lipid bilayer transporters and recent work on the use of anions to drive conformational change are highlighted (130 references). PMID:20820469

Gale, Philip A

2010-10-01

125

Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance  

SciTech Connect

This project have focuses on the basic chemical aspects of anion receptor design of functional pH independent systems, with the ultimate goal of targeting the selective binding of sulfate, as well as design of separations strategies for selective and efficient removal of targeted anions. Key findings include: (1) the first synthetic sulfate-selective anion-binding agents; (2) simple, structure-based methods for modifying the intrinsic anion selectivity of a given class of anion receptors; and (3) the first system capable of extracting sulfate anion from acidic, nitrate-containing aqueous media. Areas probed during the last funding period include: the design, synthesis, and physical and structural characterization of receptors and investigation of anion and dual ion pair extraction using lipophilic amide receptors for anion binding. A new collaboration has been added to the project in addition to the one with Dr. Bruce Moyer at Oak Ridge National Laboratory, with Professor Jonathan Sessler at the University of Texas at Austin.

Bowman-James, Kristen

2004-12-01

126

ANNUAL REPORT. SUPRAMOLECULAR CHEMISTRY OF SELECTIVE ANION RECOGNITION FOR ANIONS OF ENVIRONMENTAL RELEVANCE  

EPA Science Inventory

This project involves the design and synthesis of receptors for anions of environmental importance, including emphasis on high level and low activity waste. Polyammonium macrocycles as receptors and nitrate as target anion were the focus of the first phase of this project. A seco...

127

Anion-arene adducts: C-H hydrogen bonding, anion- interaction, and carbon bonding motifs  

SciTech Connect

This article summarizes experimental and theoretical evidence for the existence of four distinct binding modes for complexes of anions with charge-neutral arenes. These include C-H hydrogen bonding and three motifs involving the arene- system - the noncovalent anion- interaction, weakly covalent sigma interaction, and strongly covalent sigma interaction.

Hay, Benjamin [ORNL; Bryantsev, Vyacheslav S. [California Institute of Technology, Pasadena

2008-01-01

128

Bridging the Gap between Fluxomics and Industrial Biotechnology  

PubMed Central

Metabolic flux analysis is a vital tool used to determine the ultimate output of cellular metabolism and thus detect biotechnologically relevant bottlenecks in productivity. 13C-based metabolic flux analysis (13C-MFA) and flux balance analysis (FBA) have many potential applications in biotechnology. However, noteworthy hurdles in fluxomics study are still present. First, several technical difficulties in both 13C-MFA and FBA severely limit the scope of fluxomics findings and the applicability of obtained metabolic information. Second, the complexity of metabolic regulation poses a great challenge for precise prediction and analysis of metabolic networks, as there are gaps between fluxomics results and other omics studies. Third, despite identified metabolic bottlenecks or sources of host stress from product synthesis, it remains difficult to overcome inherent metabolic robustness or to efficiently import and express nonnative pathways. Fourth, product yields often decrease as the number of enzymatic steps increases. Such decrease in yield may not be caused by rate-limiting enzymes, but rather is accumulated through each enzymatic reaction. Fifth, a high-throughput fluxomics tool hasnot been developed for characterizing nonmodel microorganisms and maximizing their application in industrial biotechnology. Refining fluxomics tools and understanding these obstacles will improve our ability to engineer highlyefficient metabolic pathways in microbial hosts. PMID:21274256

Feng, Xueyang; Page, Lawrence; Rubens, Jacob; Chircus, Lauren; Colletti, Peter; Pakrasi, Himadri B.; Tang, Yinjie J.

2010-01-01

129

Cytotoxic mechanisms of hydrosulfide anion and cyanide anion in primary rat hepatocyte cultures.  

PubMed

Hydrogen sulfide and hydrogen cyanide are known to compromise mitochondrial respiration through inhibition of cytochrome c oxidase and this is generally considered to be their primary mechanism of toxicity. Experimental studies and the efficiency of current treatment protocols suggest that H(2)S may exert adverse physiological effects through additional mechanisms. To evaluate the role of alternative mechanisms in H(2)S toxicity, the relative contributions of electron transport inhibition, uncoupling of mitochondrial respiration, and opening of the mitochondrial permeability transition pore (MPTP) to hydrosulfide and cyanide anion cytotoxicity in primary hepatocyte cultures were examined. Supplementation of hepatocytes with the glycolytic substrate, fructose, rescued hepatocytes from cyanide anion induced toxicity, whereas fructose supplementation increased hydrosulfide anion toxicity suggesting that hydrosulfide anion may compromise glycolysis in hepatocytes. Although inhibitors of the MPTP opening were protective for hydrosulfide anion, they had no effect on cyanide anion toxicity, consistent with an involvement of the permeability transition pore in hydrosulfide anion toxicity but not cyanide anion toxicity. Exposure of isolated rat liver mitochondria to hydrosulfide did not result in large amplitude swelling suggesting that if H(2)S induces the permeability transition it does so indirectly through a mechanism requiring other cellular components. Hydrosulfide anion did not appear to be an uncoupler of mitochondrial respiration in hepatocytes based upon the inability of oligomycin and fructose to protect hepatocytes from hydrosulfide anion toxicity. These findings support mechanisms additional to inhibition of cytochrome c oxidase in hydrogen sulfide toxicity. Further investigations are required to assess the role of the permeability transition in H(2)S toxicity, determine whether similar affects occur in other cell types or in vivo and evaluate whether this may provide a basis for the design of more effective therapeutic measures for hydrogen sulfide intoxication. PMID:12767687

Thompson, Rodney W; Valentine, Holly L; Valentine, William M

2003-06-30

130

Photonic Band Gap  

NSDL National Science Digital Library

Created by Boyang Liu and Professor Seng-Tiong Ho at Northwestern University, and presented by the NanoEd Resource Portal, this site covers the concept of the photonic band gap. Here, visitors will find a basic description of the concept, ideas of how to incorporate it into classroom activities, and a user's manual to walk students step-by-step through the concept. There is also a link to an interactive simulation (the link is labeled Open Visualization), which allows students to adjust the wavelength and color of the light source, particle size, and incident angle to view changes to the photonic band gap. This is a thorough and useful resource for any nanotechnology classroom.

Ho, Seng-Tiong; Liu, Boyang

2012-04-12

131

An anionic surfactant for EOR applications  

NASA Astrophysics Data System (ADS)

This work is to investigate the new anionic surfactants for the Enhanced Oil Recovery (EOR) application. Sulfonated anionic surfactant was produced by attaching SO3 to an ethoxylated alcohol to increase the performance of the surfactant. Methallyl chloride and ethoxylated alcohol was reacted followed by the reaction with sodium bisulfite to produce anionic sulfonated surfactant in 80.3 % yield. The sulfonation reaction parameters such as reactants mole ratio, reaction temperature and catalyst amount were optimized. The generation and stability of foam from the synthesized surfactant is also tested and results are reported. The synthesized novel surfactant was further investigated for the effect on the CO2 mobility in porous media and the findings are presented here. This in house developed surfactant has a great potential for CO2- EOR applications.

Sagir, Muhammad; Tan, Isa M.; Mushtaq, Muhammad

2014-10-01

132

Bridging the Gap  

NSDL National Science Digital Library

A newly appointed joint hire in the College of Arts and Sciences, Department of Natural Sciences and the College of Education, Department of Middle/Secondary Education, was charged with the responsibility of bridging the communication gap between these two departments and colleges. To meet this challenge, four collaborative projects were developed between the Natural Sciences faculty and Middle/Secondary Education science students that will become formally established in future university courses.

Eason, Grace

2004-11-01

133

Filling the launch gap  

Microsoft Academic Search

Vehicles proposed to fill the gap in the U.S. space program's space transport needs for the next decade resulting from the January Challenger disaster, are discussed. Prior to the accident, the Air Force planned to purchase a Complementary Expendable Launch Vehicle system consisting of 10 single-use Titan-34D7 rockets. Another heavy lift booster now considered is the Phoenix H. Commercial launch

S. Hoeser

1986-01-01

134

Negative Ion Photoelectron Spectra of Halomethyl Anions  

NASA Astrophysics Data System (ADS)

Halomethyl anions undergo a significant geometry change upon electron photodetachment, resulting in multiple extended vibrational progressions in the photoelectron spectra. The normal mode analysis that successfully models photoelectron spectra when geometry changes are modest is unable to reproduce the experimental data using physically reasonable parameters. A three-dimensional anharmonic coupled-mode analysis was employed to accurately reproduce the observed vibrational structure. We present the 364 nm negative ion photoelectron spectra of the halomethyl anions CHX_2^- and CDX_2^- (X = Cl, Br, I) and report electron affinities, vibrational frequencies, and geometries.

Vogelhuber, Kristen M.; Wren, Scott W.; McCoy, Anne B.; Ervin, Kent M.; Lineberger, W. Carl

2009-06-01

135

Metabolic Myopathies  

MedlinePLUS

... muscles. [Metabolism refers to chemical reactions that provide energy and nutrients, or substances necessary for health and ... occur when muscle cells don’t get enough energy. Without enough energy, the muscle lacks enough fuel ...

136

Metabolism Roundup  

NSDL National Science Digital Library

Laboratory rats with large amounts of type II muscle fiber, maintained health for a longer period of time. In addition, those fed artificial sweetener tended to slow down their metabolism and show weight gain.

Science Update (AAAS;)

2008-02-29

137

Metabolic Syndrome  

Microsoft Academic Search

“Metabolic syndrome” refers to the phenomenon of risk factor clustering and is presumed to reflect a unifying underlying pathophysiology.\\u000a Clustering commonly occurs in the setting of obesity, insulin resistance and a sedentary lifestyle. Currently there are five\\u000a different criteria for metabolic syndrome, all of which are associated with increased risk of diabetes or cardiovascular disease.\\u000a Therapeutic lifestyle change that focuses

James B. Meigs

138

Anion-conducting polymer, composition, and membrane  

DOEpatents

Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

Pivovar, Bryan S. (Los Alamos, NM); Thorn, David L. (Los Alamos, NM)

2011-11-22

139

Transmembrane anion transport by synthetic systems.  

PubMed

This highlight examines recent advances in the development of synthetic membrane transporters for anions, highlighting the underlying principles of transporter design and the promising applications of such transporters to biological systems including potential future treatments for diseases like cystic fibrosis which is caused by dysregulation of chloride transport across epithelial cell membranes. PMID:21594245

Haynes, Cally J E; Gale, Philip A

2011-08-01

140

The role of anions in surface electrochemistry.  

SciTech Connect

Some issues of the current state of understanding in the surface electrochemistry are discussed, with emphases on the role of specifically adsorbing anions in hydrogen adsorption and oxide formation, adsorption and ordering of molecular adsorbates and metal ions, metal deposition, restructuring and stability of surface atoms, and kinetics of electrochemical reactions.

Tripkovic, D. V.; Strmcnik, D.; van der Vliet, D.; Stamenkovic, V,; Markovic, N. M.; Materials Science Division; Univ. of Chicago

2008-01-01

141

Anion-Conducting Polymer, Composition, and Membrane  

DOEpatents

Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

Pivovar, Bryan S. (Los Alamos, NM); Thorn, David L. (Los Alamos, NM)

2008-10-21

142

Gas-phase fragmentation of polyoxotungstate anions.  

PubMed

A series of phospho-polyoxotungstate anions was transferred to the gas phase via electrospray ionization (ESI), and the anions' fragmentation was examined by collision-induced dissociation (CID). The anions included [PW12O40]3-, [P2W18O62]6-, and {Co4(H2O)2][PW9O34]2}10- as well as lacunary and metal-substituted derivatives such as [PW11O39]7- and [MPW11O39]5- (M = Co(II), Ni(II), Cu(II)). Common species observed in the mass spectra arose from protonation and alkali metal cationization of the precursor ions. Additional species arising from the formal loss of oxide from the precursor species were also observed, presumably formed via protonation and the loss of an oxo ligand as water. These processes of protonation/cationization and the loss of water both led to species with reduced gas-phase anionic charges, and their formation appears to be driven by the enhanced effects of Coulombic repulsion in the desolvated species generated during transfer to the gas phase via ESI. Fragmentation of selected species was examined by multistage mass spectrometry experiments employing CID. Fragmentation occurred via multiple reaction channels, leading to pairs of complementary product anions whose total stoichiometry and charge matched those of the precursor anion. For example, [PW12O40]3- fragmented to give pairs of product ions of general formulas [W(x)O(3x+1)]2- and [PW(12-x)O(39-3x)]- (x = 6-9), with the most intense pair being [W6O19]2- and [PW6O21]-. Similar ions were also observed for fragmentation of [P2W18O61]4- (derived from the loss of water from [P2W18O62]6-). The lacunary and M(II)-substituted lacunary systems fragmented via related pathways, with the latter generating additional fragment ions due to the presence of M(II). These results highlight the usefulness of ESI-MS in the characterization of complex polyoxometalate anion clusters. PMID:19072590

Ma, Michelle T; Waters, Tom; Beyer, Karin; Palamarczuk, Rosemary; Richardt, Peter J S; O'Hair, Richard A J; Wedd, Anthony G

2009-01-19

143

SUPRAMOLECULAR CHEMISTRY OF SELECTIVE ANION RECOGNITION FOR ANIONS OF ENVIRONMENTAL RELEVANCE  

EPA Science Inventory

The supramolecular chemistry of selective anion recognition by synthetic polyammonium macrocycles will be explored in a comprehensive, long term program designed to provide new solutions to problems critical to the environmental initiative of DOE. Highly shape- and charge selecti...

144

Bipyrrole-Strapped Calix[4]pyrroles: Strong Anion Receptors That Extract the Sulfate Anion.  

PubMed

Cage-type calix[4]pyrroles 2 and 3 bearing two additional pyrrole groups on the strap have been synthesized. Compared with the parent calix[4]pyrrole (1), they were found to exhibit remarkably enhanced affinities for anions, including the sulfate anion (TBA(+) salts), in organic media (CD2Cl2). This increase is ascribed to participation of the bipyrrole units in anion binding. Receptors 2 and 3 extract the hydrophilic sulfate anion (as the methyltrialkyl(C8-10)ammonium (A336(+)) salt) from aqueous media into a chloroform phase with significantly improved efficiency (>10-fold relative to calix[4]pyrrole 1). These two receptors also solubilize into chloroform the otherwise insoluble sulfate salt, (TMA)2SO4 (tetramethylammonium sulfate). PMID:25254498

Kim, Sung Kuk; Lee, Juhoon; Williams, Neil J; Lynch, Vincent M; Hay, Benjamin P; Moyer, Bruce A; Sessler, Jonathan L

2014-10-22

145

Bipyrrole-Strapped Calix[4]pyrroles: Strong Anion Receptors That Extract the Sulfate Anion  

SciTech Connect

Cage-type calix[4]pyrroles 2 and 3 bearing two additional pyrrole groups on the strap have been synthesized. Compared with the parent calix[4]pyrrole (1), they were found to exhibit remarkably enhanced affinities for anions, including the sulfate anion (TBA+ salts), in organic media (CD2Cl2). This increase is ascribed to participation of the bipyrrole units in anion binding. Receptors 2 and 3 extract the hydrophilic sulfate anion (as the methyltrialkyl(C8-10)ammonium (A336+) salt)) from aqueous media into a chloroform phase with significantly improved efficiency (>10-fold relative to calix[4]pyrrole 1). These two receptors also solubilize into chloroform the otherwise insoluble sulfate salt, (TMA)2SO4 (tetramethylammonium sulfate).

Kim, Sung Kuk [University of Texas at Austin; Lee, Juhoon [University of Texas at Austin; Williams, Neil J [ORNL; Lynch, Vincent M. [University of Texas at Austin; Hay, Benjamin [ORNL; Moyer, Bruce A [ORNL; Sessler, Jonathan L. [University of Texas

2014-01-01

146

Pharmacological "cross-inhibition" of connexin hemichannels and swelling activated anion channels.  

PubMed

The study of ion channels has relied heavily on the use of pharmacological blocking agents. However, many of these agents have multiple effects, which may compromise interpretation of results when the affected mechanisms/pathways mediate similar functions. Volume regulated anion channels (VRAC) and connexin hemichannels can both mediate the release of glutamate and taurine, although these channels have distinct activation stimuli and hemichannels, but not VRAC, are permeable to Lucifer Yellow (LY). It has been reported that some anion channel blockers may inhibit connexin hemichannels. We further examined the effects of classic gap junction/hemichannel blockers and anion channel blockers on these channels. The typical VRAC blockers, NPPB, IAA-94, and tamoxifen blocked low divalent cation-induced glutamate and taurine release and LY loading, presumed due to hemichannel opening. The blocking action of these compounds on hemichannels was concentration dependent and fell within the same range where the drugs classically block VRACs. Conversely, carbenoxolone (CBX), the most widely used gap junction/hemichannel blocker, was an effective blocker of VRAC-mediated glutamate and taurine release, and blocked these channels at similar concentrations at which it blocked hemichannels. The CBX effect on VRACs was verified using astrocytes from connexin 43 knock out (Cx43 KO) animals. In these cells, the hypotonic induced amino acid flux was retained whereas the low divalent cation solution-induced flux was lost. These results extend our knowledge about "cross-inhibition" of VRACs and gap junctions/hemichannels by certain pharmacological agents. Given the overlap in function of these two types of channels, great care must be exerted in using pharmacological blockers to identify one channel from the other. PMID:18837047

Ye, Zu-Cheng; Oberheim, Nancyann; Kettenmann, Helmut; Ransom, Bruce R

2009-02-01

147

Advances in anion supramolecular chemistry: from recognition to chemical applications.  

PubMed

Since the start of this millennium, remarkable progress in the binding and sensing of anions has been taking place, driven in part by discoveries in the use of hydrogen bonding, as well as the previously under-exploited anion-? interactions and halogen bonding. However, anion supramolecular chemistry has developed substantially beyond anion recognition, and now encompasses a diverse range of disciplines. Dramatic advance has been made in the anion-templated synthesis of macrocycles and interlocked molecular architectures, while the study of transmembrane anion transporters has flourished from almost nothing into a rapidly maturing field of research. The supramolecular chemistry of anions has also found real practical use in a variety of applications such as catalysis, ion extraction, and the use of anions as stimuli for responsive chemical systems. PMID:25204549

Evans, Nicholas H; Beer, Paul D

2014-10-27

148

Temperature Dependence of the Mitochondrial Inner Membrane Anion Channel  

E-print Network

ions, such as Cl and HCO3 , to multicharged anions, such as citrate, ferrocya- nide, and even ATP of the potassium ionophore valinomycin to mitochon- dria suspended in potassium salts of the test anion (1

Abraham, Nader G.

149

Neutralization dynamics of hydrogen anions near flat and vicinal surfaces^  

NASA Astrophysics Data System (ADS)

I will scrutinize the role of intermediate electronic surface and image states on the charge-transfer dynamics during collisions of H^- anions with atomically flat Pd, Cu, and Ag surfaces of (100) and (111) symmetries using a wave-packet propagation approach [1]. For these surfaces I will show how differently located band gaps, surface -, and image states lead to easily visualized differences in the evolution of the active electron's probability density: i)Long-lived surface states of the (111) surfaces tend to localize electronic density near the surface and facilitate recapture by the projectile, while H^- is more efficiently neutralized near (100) surfaces whose surface state appears as a broad resonance embedded in the bulk valence band. ii) Image states that are degenerate with the metal conduction band favor, while image states that are degenerate with the band gap hinder recapture. In the second part of my talk I will discuss negative-ion interactions with stepped nano-structured surfaces based on effective potentials for the active electron's interaction with the surface that we derived within a Thomas-Fermi von Weizsaecker model [2]. For 50eV projectiles, we find an enhancement of electron loss near the steps due to the Smoluchowski effect. In consequence, negative-ion survival is more likely for projectiles that approach steps from above than from below [3]. ^ In collaboration with Himadri Chakraborty (Northwest Missouri State Univ.) and Boyan Obreshkov (Kansas State Univ.) [1] H. Chakraborty, T. Niederhausen, and U. Thumm., Nucl. Instrum. Meth. B 241, 43 (2005) ; Phys. Rev. A 70, 052903 (2004). [2] B. Obreshkov and U. Thumm, Phys. Rev. A 74, 012901 (2006); [3] B. Obreshkov and U. Thumm, Surf. Sci. 601, 622 (2007).

Thumm, Uwe

2008-10-01

150

Metabolic analyzer  

NASA Technical Reports Server (NTRS)

The metabolic analyzer was designed to support experiment M171. It operates on the so-called open circuit method to measure a subject's metabolic activity in terms of oxygen consumed, carbon dioxide produced, minute volume, respiratory exchange ratio, and tidal volume or vital capacity. The system operates in either of two modes. (1) In Mode I, inhaled respiratory volumes are actually measured by a piston spirometer. (2) In Mode II, inhaled volumes are calculated from the exhaled volume and the measured inhaled and exhaled nitrogen concentrations. This second mode was the prime mode for Skylab. Following is a brief description of the various subsystems and their operation.

Lem, J. D.

1977-01-01

151

SIMULATING METABOLISM OF XENOBIOTIC CHEMICALS AS A PREDICTOR OF TOXICITY  

EPA Science Inventory

EPA is faced with long lists of chemicals that need to be assessed for hazard. A major gap in evaluating chemical risk is accounting for metabolic activation resulting in increased toxicity. The goals of this project are to develop a capability to forecast the metabolism of xenob...

152

Multinuclear NMR investigation of the formation of aluminosilicate anions  

SciTech Connect

The structure of simple aluminosilicate anions formed by the reaction of silicate and aluminate anions was investigated by {sup 29}Si and {sup 27}Al NMR spectroscopy. The extent of aluminosilicate formation was found to increase with increasing silicate ratio and increasing cation size. The first of these trends is attributed to the redistribution of Si with increasing silicate ratio to more acidic anions. The second trend is attributed to the formation of cation-anion pairs.

McCormick, A.V.; Bell, A.T.; Radke, C.J. (Lawrence Berkeley Lab., CA (USA))

1989-03-09

153

Removing Aquatic Organic Substances by Anion Exchange Resins  

Microsoft Academic Search

The focus of this study was verification of the mechanisms of removal of aquatic organic substances by anion exchange resins, influence of resin properties and clarification processes on removal, and Chromatographie behavior of organic substances in anion exchange columns. Depending on the type of resin and the nature of the organic matter, anion exchange resins removed up to 80 percent

Paul L. K. Fu; James M. Symons

1990-01-01

154

Photoelectron imaging of tetrahydrofuran cluster anions ,,1 n 100...  

E-print Network

Photoelectron imaging of tetrahydrofuran cluster anions ,,THF...n - ,,1 n 100... Ryan M. Young,1 2010 Anionic tetrahydrofuran clusters THF n - 1 n 100 are studied with photoelectron imaging as gas, we report experiments in which tetrahydrofuran cluster anions THF n - are observed for the first time

Neumark, Daniel M.

155

Biosorption of anionic metal complexes Hui Niu and Bohumil Volesky*  

E-print Network

concentration range. This work focuses on biosorption of anionic metal complexes such as gold cyanide (AuCN21 Biosorption of anionic metal complexes Hui Niu and Bohumil Volesky* http Street, MONTREAL, Canada H3A 2B2 *corresponding author Anionic metal complexes, are very effectively

Volesky, Bohumil

156

Anion- interactions in crystal structures: commonplace or extraordinary?  

SciTech Connect

An in-depth analysis of the distribution of anions about planar six-membered rings in the Cambridge Structural Database fails to provide any convincing evidence for anion- interactions with charge-neutral systems, but does provide overwhelming evidence in support of C-H---anion hydrogen bonding.

Hay, Benjamin [ORNL; Custelcean, Radu [ORNL

2009-01-01

157

Effect of anion channel blockers on L-arginine action in spermatozoa from asthenospermic men.  

PubMed

In earlier studies, we have established that l-arginine enhances motility and metabolic rate in spermatozoa of goat, bull and mouse. In the present study this work was extended to human sperm cells obtained from the semen samples of asthenospermic patients, which are characterised by low motility. The metabolic rate was followed by monitoring the glucose consumption (1-(13)C glucose as substrate) and the production of lactate in sperm cells, using (13)C NMR. The stimulatory effect of l-arginine was neutralised on adding an NO-synthase inhibitor like N(omega)-nitro-L-arginine methyl ester. On the other hand, the inactive d-enantiomorph did not affect the stimulatory effect of l-arginine. This strongly suggests that L-arginine acts through the NO signal pathway. We also demonstrated that the stimulatory effect of L-arginine was inhibited in the presence of anion channel inhibitors like 4-acetamido-4'-isothiocyanostilbene-2,2'-disulphonic acid, 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone. Furthermore, bicarbonate supplementation was found to be essential for the action of L-arginine. These observations indicate that L-arginine induces NO synthesis and stimulates motility and metabolism only when an active anion transport system is present. PMID:20384796

Srivastava, S; Agarwal, A

2010-04-01

158

Gap Domain Wall Fermions  

E-print Network

I demonstrate that the chiral properties of Domain Wall Fermions (DWF) in the large to intermediate lattice spacing regime of QCD, 1 to 2 GeV, are significantly improved by adding to the action two standard Wilson fermions with supercritical mass equal to the negative DWF five dimensional mass. Using quenched DWF simulations I show that the eigenvalue spectrum of the transfer matrix Hamiltonian develops a substantial gap and that the residual mass decreases appreciatively. Furthermore, I confirm that topology changing remains active and that the hadron spectrum of the added Wilson fermions is above the lattice cutoff and therefore is irrelevant. I argue that this result should also hold for dynamical DWF and furthermore that it should improve the chiral properties of related fermion methods.

Pavlos M. Vranas

2006-06-22

159

Effort Gap Database  

NSDL National Science Digital Library

Maintained by the Biological Resources Research Center (BRRC) at the University of Nevada, Reno, the Effort Gap Database organizes information on biological research efforts in the Great Basin. Users may search the database (by multiple topics) for current and past projects, or they may add new information to the database. Typical returns provide information such as project title, scientific goals, available data, Principal Investigators, temporal and spatial scale of research, habitats in study area, types of organisms, source of funding, and finished products. Designed as an interactive Web application to allow and encourage researchers to share research foci and learn about other conservation biology projects in Nevada, this database is an excellent example of how to facilitate collaboration across multiple ecological scales and agencies.

160

Filling the launch gap  

NASA Astrophysics Data System (ADS)

Vehicles proposed to fill the gap in the U.S. space program's space transport needs for the next decade resulting from the January Challenger disaster, are discussed. Prior to the accident, the Air Force planned to purchase a Complementary Expendable Launch Vehicle system consisting of 10 single-use Titan-34D7 rockets. Another heavy lift booster now considered is the Phoenix H. Commercial launch vehicle systems projected to be available in the necessary time frame include the 215,000-pound thrust 4000-pound LEO payload capacity NASA Delta, the 11,300-pound LEO payload capacity Atlas Centaur the first ICBM, and the all-solid propellant expendable 2000-pound LEO payload Conestoga rocket. Also considered is the man-rated fully reusable Phoenix vertical take-off and vertical-landing launch vehicle.

Hoeser, S.

1986-05-01

161

Metabolic cardiomyopathies  

PubMed Central

The energy needed by cardiac muscle to maintain proper function is supplied by adenosine Ariphosphate primarily (ATP) production through breakdown of fatty acids. Metabolic cardiomyopathies can be caused by disturbances in metabolism, for example diabetes mellitus, hypertrophy and heart failure or alcoholic cardiomyopathy. Deficiency in enzymes of the mitochondrial ?-oxidation show a varying degree of cardiac manifestation. Aberrations of mitochondrial DNA lead to a wide variety of cardiac disorders, without any obvious correlation between genotype and phenotype. A completely different pathogenetic model comprises cardiac manifestation of systemic metabolic diseases caused by deficiencies of various enzymes in a variety of metabolic pathways. Examples of these disorders are glycogen storage diseases (e.g. glycogenosis type II and III), lysosomal storage diseases (e.g. Niemann-Pick disease, Gaucher disease, I-cell disease, various types of mucopolysaccharidoses, GM1 gangliosidosis, galactosialidosis, carbohydrate–deficient glycoprotein syndromes and Sandhoff's disease). There are some systemic diseases which can also affect the heart, for example triosephosphate isomerase deficiency, hereditary haemochromatosis, CD 36 defect or propionic acidaemia. PMID:11298185

Guertl, Barbara; Noehammer, Christa; Hoefler, Gerald

2000-01-01

162

External-anion-dependent anionic current in blastoderm cells of early medaka fish embryos.  

PubMed Central

1. Anionic current was studied by a whole-cell variation of the patch-clamp technique in blastoderm cells dissociated from medaka (Oryzias latipes) embryos at the early blastula stage. The blastoderm cells were mechanically dissociated without using proteolytic enzymes. 2. The anionic current was deactivated by hyperpolarizing steps. The steady-state current-voltage (I-V) relationship of the anion current was accurately represented by the Boltzmann relation with z = 1.01 +/- 0.02 (+/- S.E.M., n = 4) for voltage-dependent activation when internal calcium ions were buffered at 100 nM by BAPTA-Ca2+ buffer. 3. When the internal calcium concentration was reduced to 10 nM, this anionic current became an external-calcium-dependent current and was remarkably decreased by removal of external calcium ions. Furthermore, this anionic current was almost abolished when the internal calcium concentration was greatly reduced by chelating Ca2+ ions with 10 mM BAPTA. 4. This current was not affected by replacing external Na+ with TEA+ or N-methyl-D-glucamine. The reversal potentials shifted by +58.6 mV for a 10-fold decrease in the external Cl-concentration. External Cl-ions were substituted with various anions and respective current-reversal potentials were measured. The order of permeability was I- > Br- > Cl- > F-. Both the outward and inward currents almost disappeared in external Cl(-)-free solutions. 5. The voltage dependency of the anionic current shifted in a positive direction with the reduction in the external Cl- concentration, the potentials at which half the channels were activated (V 1/2) being -59.8 +/- 1.2 mV (n = 4), -40.7 +/- 0.8 mV (n = 4), -14.9 +/- 0.7 mV (n = 4), and -0.7 +/- 0.6 mV (n = 4) for 135, 90, 67, and 45 mM Cl-, respectively. This implies that the inward current, brought by efflux of internal anions, decreases with reductions in the external Cl- concentration. In the presence of external 135 mM Br-, the voltage dependency of the anionic current shifted in the negative direction (V 1/2 = -84.5 +/- 1.0 mV and z = 0.91 +/- 0.02 (n = 3)) in comparison with that in the external Cl- medium. It further shifted in the negative direction in the presence of 135 mM I- (V 1/2 = -93.8 +/- 1.5 mV and z = 0.85 +/- 0.03 (n = 3)). The inward current of the anion channel is considered to be affected by both the type and the concentration of external halide ions. 6. At the beginning of the blastula stage, the blastocoel cavity is formed for the first time. A mechanism is necessary to transport ions to the cavity without losing them to pond water outside the embryos. Since this anion channel is external-anion dependent, the current cannot be activated in the membrane facing the pond water, where concentrations of anions are much lower than those of the intracavernous solution. Only after blastocoel formation are blastoderm cells first exposed to the extracellular fluid with high ionic concentrations. Then, the anion channel would become effective for maintaining the Cl- equilibrium potential. PMID:8866351

Shigemoto, T; Okada, Y

1996-01-01

163

Temporary anion states of three herbicide families.  

PubMed

Electron scattering studies are used to locate the energies of temporary negative ion states of three chloro-substituted molecular families of herbicidal importance: salicylic and phenoxyacetic acids and acetamides. The correlation between these energies and the computed virtual orbital energies of the compounds is examined and used to put the latter on an absolute energy scale. Such scaling of orbital energies permits the anion states of other members of these families, for which experimental data may not be available, to be estimated from the calculated orbital energies. Studies of electron reduction rates often rely on calculated LUMO energies as molecular descriptors. The use of measured anion energies as well as appropriately scaled orbital energies should serve to improve such studies in these and in related herbicides. PMID:24261843

Scheer, A M; Aflatooni, K; Gallup, G A; Burrow, P D

2014-09-01

164

Cation-anion Ratios of Plants  

Microsoft Academic Search

DIJKSHOORN1 has recently summarized the results of many analyses for the total equivalents of metals (potassium, sodium, magnesium, calcium) and non-metals (nitrogen, phosphorus, sulphur, chlorine) in Lolium perenne, and has calculated the balance of acidity within the plant following on the higher intake of non-metals as anions. From the content (in equiv.\\/kg) of metals as 1.8 and non-metals as 3.2

G. W. Leeper

1965-01-01

165

Collision-induced dissociation of fluoropyridinide anions  

NASA Astrophysics Data System (ADS)

Collision-induced dissociation of ortho-fluoro, meta-fluoro, and 2,6-difluoropyridinide anions are studied using the selected ion flow tube technique. Structures and energetics of the reactants, transition states, and products are calculated at the MP4(SDQ)/6-31 + G(d) level of theory based on the B3LYP/6-311++G(d,p) and/or MP2/6-31 + G(d) optimized geometries. The monofluoropyridinide anions (C5NH3F-) dissociate almost exclusively via loss of an HF molecule, i.e., C5NH2- + HF at low collision energies, in addition to loss of F- at higher energies. 2,6-Difluoropyridinide anions (C5NH2F2-) dissociate via successive loss of HF molecules to form C5NHF- then C5N- depending on the collision energy. The CID results strongly suggest formation of ring-intact pyridynide structures (C5NH2-, C5NHF-) with a bent triple bond embedded in the azine ring systems. Calculated reaction energy diagrams are totally consistent with the experimental observations. Didehydropyridynides C5NH2- and C5NHF- have substantial barriers to decomposition. Tetradehydropyridynide C5N- is a highly strained ring system and metastable with a predicted barrier of about 5 kcal mol-1 (20 kJ mol-1) toward ring-opening to a linear NCCCCC- structure. The observed C5N- species is most likely the linear anion under experimental conditions; however, the ring-intact C5N- pyridynide is a highly energetic species releasing about 80 kcal mol-1 (340 kJ mol-1) of energy upon the ring-opening.

Kato, Shuji; Lineberger, W. Carl; Bierbaum, Veronica M.

2007-10-01

166

Deuterium anions in inertial electrostatic confinement devices  

Microsoft Academic Search

A magnetic deflection-energy analyzer and Faraday trap diagnostic have been used to make measurements of divergent deuterium anion flow in the inertial electrostatic confinement experiment at the University of Wisconsin-Madison (UW-IEC) [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, I. E. Radel, and A.

D. R. Boris; E. Alderson; G. Becerra; D. C. Donovan; B. Egle; G. A. Emmert; L. Garrison; G. L. Kulcinski; J. F. Santarius; C. Schuff; S. J. Zenobia

2009-01-01

167

Enhancement of platelet function by superoxide anion.  

PubMed Central

During the aerobic conversion of xanthine to uric acid by xanthine oxidase, superoxide anion and hydrogen peroxide are produced along with the hydroxyl radical. Our studies demonstrate that washed human platelets incubated with xanthine and xanthine oxidase aggregated and released [14C]serotonin. Aggregation and release were dependent on the duration of exposure to xanthine oxidase as well as the concentration of enzyme. Both reactions were inhibited by the superoxide scavenger enzyme superoxide dismutase but not by catalase, or the free radical scavenger mannitol, suggesting that they were induced by superoxide anion. Superoxide-dependent release was inhibited by prior incubation of platelets with 1 mM EDTA, 1 micronM prostaglandin E1, or 1 mM dibutyryl cyclic AMP, but was unaffected by 1 mM acetylsalicylic acid or 1 micronM indomethacin. After prolonged incubation with xanthine and xanthine oxidase there was also efflux of up to 15% of intraplatelet 51Cr, a cytosol marker. This leakage was prevented by the addition of catalase to the media but not by superoxide dismutase. Incubation with xanthine and xanthine oxidase did not produce malonyldialdehyde, the three-carbon fatty acid fragment produced during prostaglandin endoperoxide synthesis and lipid peroxidation. Prior exposure of platelets to low fluxes of superoxide anion lowered the threshold for release by subsequent addition of thrombin, suggesting a synergistic effect. We conclude that superoxide-dependent aggregation and release may be a physiologically important method to modulate hemostatic reactions particularly in areas of inflammation or vessel injury which could have high local concentrations of superoxide anion. PMID:192766

Handin, R I; Karabin, R; Boxer, G J

1977-01-01

168

Fractionation of Heparin on an Anion Exchanger  

Microsoft Academic Search

PREPARATIONS of heparin have been shown to be heterogeneous by a variety of techniques1,2, but no method is available for the fractionation of bulk quantities of heparin or of other sulphomucopolysaccharides. These compounds carry a strong negative charge over a wide range of pH, and, therefore, it seemed possible that they could be purified on basic resins. Five anion-exchange resins

J. P. Green

1960-01-01

169

A new action photoelectron spectroscopy for anions  

NASA Astrophysics Data System (ADS)

We present a new experimental approach, in which anion photodetachment spectroscopy is recorded with electrons of fixed kinetic energy. This approach circumvents some shortcomings of the zero electron kinetic energy method. Our method is based on a modified magnetic bottle photoelectron spectrometer (MBPES). A tunable laser is used to detach electrons from mass selected anions, drifting collinearly with the 40 cm MBPES drift tube. To avoid Doppler broadening, a low voltage pulse removes the velocity component of anions from the detached electrons. Spectra are recorded by collecting the wavelength dependence of electron-signal at a predetermined TOF window, corresponding to a specific electron-kinetic energy. We call this approach PEACE, denoting photoelectron action spectroscopy at constant kinetic energy. Our best resolution is 0.65 meV for 1.5 meV electrons. We present a PEACE spectrum of HgCl- together with the corresponding simulated theoretical spectrum. The method is similar in resolution and data collection rates to the slow electron velocity map imaging technique recently introduced by Neumark and co-workers.

Wolf, Israel; Ronen, Shai; Giniger, Rina; Cheshnovsky, Ori

2005-04-01

170

Fluorescence quenching of etilefrine by acetate anion  

NASA Astrophysics Data System (ADS)

Acid dissociation in the excited state of antihypotensor drug etilefrine [2-(ethylamino1-3-hydroxyphenyl)ethanol] is studied. Fluorescence of etilefrine decreases at pH<7 and is related to phenolic group dissociation. However, intensity of etilefrine fluorescence diminishes as the concentration of the acetate anion increases at pH>7. Analyses of the absorption and fluorescence spectra of aqueous solutions of etilefrine in the presence of acetate anions have been made. Considering the existence of an equilibrium in the excited state the values of 3.47×10 -9 and 0.216×10 -9 M -1 s -1 have been obtained for the rate constants for direct and inverse reactions, respectively. Moreover, the lifetime ( ?0'=0.58×10 -9 s) and quantum yield (0.01) of non-protonated etilefrine have been determined. Our results seem to support the existence of a dynamic quenching process based on a proton transfer mechanism induced by acetate anions. This process could represent a serious inconvenience in analytical fluorimetric techniques taking into account that the acetic acid/acetate pair is commonly used as a buffer. Additional fluorescence quenching by H + ions could be involved in acid aqueous mediums. At high concentrations of acetic acid, a value of 2.98×10 -9 M -1 s -1 for the bimolecular constant for the quenching by H + has been calculated.

Quintero Osso, B.; Carazo Rodríguez, F. M.; Morales Domingo, J. J.; Cabeza González, M. C.; Thomas Gómez, J.

1999-02-01

171

Gap and stripline combined monitor  

DOEpatents

A combined gap and stripline monitor device for measuring the intensity and position of a charged particle beam bunch in a beam pipe of a synchrotron radiation facility is disclosed. The monitor has first and second beam pipe portions with an axial gap therebetween. An outer pipe cooperates with the first beam pipe portion to form a gap enclosure, while inner strips cooperate with the first beam pipe portion to form a stripline monitor, with the stripline length being the same as the gap enclosure length. 4 figs.

Yin, Y.

1986-08-19

172

Gap and stripline combined monitor  

DOEpatents

A combined gap and stripline monitor device for measuring the intensity and position of a charged particle beam bunch in a beam pipe of a synchrotron radiation facility. The monitor has first and second beam pipe portions with an axial gap therebetween. An outer pipe cooperates with the first beam pipe portion to form a gap enclosure, while inner strips cooperate with the first beam pipe portion to form a stripline monitor, with the stripline length being the same as the gap enclosure length.

Yin, Y.

1984-02-16

173

Gap and stripline combined monitor  

DOEpatents

A combined gap and stripline monitor device (10) for measuring the intensity and position of a charged particle beam bunch in a beam pipe of a synchotron radiation facility. The monitor has first and second beam pipe portions (11a, 11b) with an axial gap (12) therebetween. An outer pipe (14) cooperates with the first beam pipe portion (11a) to form a gap enclosure, while inner strips (23a-d) cooperate with the first beam pipe portion (11a) to form a stripline monitor, with the stripline length being the same as the gap enclosure length.

Yin, Yan (Palo Alto, CA)

1986-01-01

174

Relationship Between Expression of Voltage-Dependent Anion Channel (VDAC) Isoforms and Type of Hexokinase Binding Sites on Brain Mitochondria  

Microsoft Academic Search

Voltage-dependent anion channels (VDAC) are pore-forming proteins found in the outer mitochondrial membrane of eukaryotes.\\u000a VDACs are known to play an essential role in cellular metabolism and in early stages of apoptosis. In mammals, three VDAC\\u000a isoforms have been identified. A proteomic approach was exploited to study the expression of VDAC isoforms in rat, bovine,\\u000a and chicken brain mitochondria. Given

Mirele Daiana Poleti; Andrea Cristina Tesch; Carla Rossini Crepaldi; Gustavo Henrique Martins Ferreira Souza; Marcos Nogueira Eberlin; Marcelo de Cerqueira César

2010-01-01

175

One gap, two gaps, and universality in high temperature superconductors  

NASA Astrophysics Data System (ADS)

A dramatic change in energy gap anisotropy upon reducing carrier concentration has often been observed in the cuprate high temperature superconductors (HTSC). A simple d-wave gap in materials with the optimal Tc evolves with underdoping into a ?two-gap? structure, with different dependences in different regions of momentum space. It is tempting to associate the large antinodal gap with a second order parameter distinct from d-wave superconductivity. We use angle-resolved photoemission spectroscopy (ARPES) to show that this two-gap behavior, and the concomitant destruction of well defined electronic excitations, are not universal features of HTSC, and depend sensitively on how the underdoped materials are prepared. Depending on cation substitution, underdoped crystals either show two-gap behavior or not. In contrast, many characteristics of HTSC like the superconducting dome (Tc versus doping), nodal quasiparticles, antinodal gap that decreases monotonically with doping, and the pseudogap, are present in all samples, irrespective of whether they exhibit two-gap behavior or not. Our results imply that universal aspects of high Tc superconductivity are insensitive to differences in the electronic states in the antinodal region of the Brillouin zone.

Zhao, Junjing; Chatterjee, Utpal; Norman, Mike; Randeria, Mohit; Campuzano, Juan Carlos

2012-02-01

176

The relationship between anion exchange and net anion flow across the human red blood cell membrane  

PubMed Central

The conductive (net) anion permeability of human red blood cells was determined from net KCl or K2SO4 effluxes into low K+ media at high valinomycin concentrations, conditions under which the salt efflux is limited primarily by the net anion permeability. Disulfonic stilbenes, inhibitors of anion exchange, also inhibited KCl or K2SO4 efflux under these conditions, but were less effective at lower valinomycin concentrations where K+ permeability is the primary limiting factor. Various concentrations of 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) had similar inhibitory effects on net and exchange sulfate fluxes, both of which were almost completely DIDS sensitive. In the case of Cl-, a high correlation was also found between inhibition of net and exchange fluxes, but in this case about 35% of the net flux was insensitive to DIDS. The net and exchange transport processes differed strikingly in their anion selectivity. Net chloride permeability was only four times as high as net sulfate permeability, whereas chloride exchange is over 10,000 times faster than sulfate exchange. Net OH- permeability, determined by an analogous method, was over four orders of magnitude larger than that of Cl-, but was also sensitive to DIDS. These data and others are discussed in terms of the possibility that a common element may be involved in both net and exchange anion transport. PMID:15047

1977-01-01

177

Hydrogen sulfide anion regulates redox signaling via electrophile sulfhydration  

PubMed Central

An emerging aspect of redox signaling is the pathway mediated by electrophilic byproducts, such as nitrated cyclic nucleotide (for example, 8-nitroguanosine 3?,5?-cyclic monophosphate (8-nitro-cGMP)) and nitro or keto derivatives of unsaturated fatty acids, generated via reactions of inflammation-related enzymes, reactive oxygen species, nitric oxide and secondary products. Here we report that enzymatically generated hydrogen sulfide anion (HS?) regulates the metabolism and signaling actions of various electrophiles. HS? reacts with electrophiles, best represented by 8-nitro-cGMP, via direct sulfhydration and modulates cellular redox signaling. The relevance of this reaction is reinforced by the significant 8-nitro-cGMP formation in mouse cardiac tissue after myocardial infarction that is modulated by alterations in HS? biosynthesis. Cardiac HS?, in turn, suppresses electrophile-mediated H-Ras activation and cardiac cell senescence, contributing to the beneficial effects of HS? on myocardial infarction–associated heart failure. Thus, this study reveals HS?-induced electrophile sulfhydration as a unique mechanism for regulating electrophile-mediated redox signaling. PMID:22772154

Nishida, Motohiro; Sawa, Tomohiro; Kitajima, Naoyuki; Ono, Katsuhiko; Inoue, Hirofumi; Ihara, Hideshi; Motohashi, Hozumi; Yamamoto, Masayuki; Suematsu, Makoto; Kurose, Hitoshi; van der Vliet, Albert; Freeman, Bruce A; Shibata, Takahiro; Uchida, Koji; Kumagai, Yoshito; Akaike, Takaaki

2014-01-01

178

Cellular Metabolism  

NSDL National Science Digital Library

This is a lesson about the evidence for life on other planets. Learners will play a game to examine processes in cellular metabolism and explore both direct and indirect evidence for fingerprints of life. Includes teacher notes, learning objectives, and assessment of prior knowledge and preconceptions. This is Lesson 2 in Exploring Deep-Subsurface Life. Earth Analogues for Possible Life on Mars: Lessons and Activities.

179

Metabolic syndrome  

Microsoft Academic Search

The metabolic syndrome is like an elephant, and any literary review of its importance is shamefully reduced to an examination\\u000a of tusks, trunk, and tail. Evidence continues to mount that this diminutive approach is an incorrect management strategy for\\u000a such a large problem. Diet and lifestyle are effective strategies, but they must effectively compete with behaviors that have\\u000a instant gratification.

Margo A. Denke

2002-01-01

180

ISABELLE cavity gap assemblies  

SciTech Connect

In a storage ring, where beam lifetime is measured in hours, it is necessary to keep the longitudinal impedance, as seen by the beam, very low, even into the gigahertz region. This is necessary to prevent the excitation of longitudinal instabilities. These impedances are due to the resistive wall effect and any deviation from a smooth vacuum chamber such as at pick-up electrodes, vacuum pump stations, rf cavities, etc. At low frequencies, up to 10 to 20 MHz, the low impedance requirement for the cavities can be satisfied by designing the driving power amplifiers with a very low output impedance. For ISABELLE a method has been designed for building a network into the cavity accelerating gaps which will satisfy the impedance criteria to at least 1300 MHz. The maximum allowable impedance at any frequency, f, is given in the form Z/n where n = f/f/sub rotation/. For the ISABELLE accelerating cavity, operating at 235.5 KHz, Z/n must be less than 10 ohms. For the stacking cavity, operating at 4.45 MHz, Z/n < 1 ohm.

Plotkin, M

1981-01-01

181

Research and Applications: Gap Analysis  

NSDL National Science Digital Library

The US Geological Survey's Gap Analysis Program (GAP) is a cooperative project that attempts to map land cover and vertebrate species distribution in order to enhance conservation land management activities. Visitors can view data about protected areas and species as well as read USGS publications on this program.

2001-01-01

182

Color Evaporation Induced Rapidity Gaps  

E-print Network

We show that soft color rearrangement of final states can account for the appearance of rapidity gaps between jets. In the color evaporation model the probability to form a gap is simply determined by the color multiplicity of the final state. This model has no free parameters and reproduces all data obtained by the ZEUS, H1, D0, and CDF collaborations.

O. J. P. Eboli; E. M. Gregores; F. Halzen

1999-08-16

183

Capillary ion electrophoresis of endogenous anions and anionic adulterants in human urine.  

PubMed

Normal human urine contains many anions and cations. Ionic concentrations in urine have classically been determined by spectrophotometry of color reactions, flame emission spectrophotometry, atomic absorption spectrophotometry, high performance liquid chromatography, or potentiometry with ion-specific electrodes. Capillary ion electrophoresis (CIE) is a form of capillary electrophoresis which uses the differential electrophoretic mobility of ions to perform a separation of an ionic mixture. Various salts can be added to urine specimens to abnormally elevate ionic concentrations and interfere with either immunoassay urine drug screening procedures or gas chromatographic/mass spectrometric confirmation techniques. Application of CIE for the direct detection of endogenous anions and anionic adulterants in human urine specimens was the purpose of this investigation. CIE was performed using a Waters Quanta 4000 Capillary Electrophoresis System with either direct or indirect ultraviolet absorption detection at 254 nm. CIE of 30 random normal urine specimens and 21 urine specimens suspected of adulteration was performed. Duplicate aliquots were assayed by CIE and by colorimetric technique for nitrite. Sixteen specimens had elevated concentrations of nitrite and/or nitrate. The correlation coefficient between nitrite CIE and colorimetric results was 0.9895. Three specimens had detectable concentrations of chromate and were suspected of being adulterated with "Urine Luck," an adulterant found to contain chromate. Two specimens suspected of being adulterated with bleach were found to only contain chloride, sulfate, and phosphate. CIE is applicable to forensic analysis of urine anion concentrations. CIE can easily quantitate numerous endogenous anions and offers a method to detect and/or confirm anion adulteration of urine specimens. PMID:11372999

Ferslew, K E; Hagardorn, A N; Robert, T A

2001-05-01

184

Bridging the Vector Calculus Gap  

NSDL National Science Digital Library

This paper was written collaboratively by a physicist and a mathematician to raise awareness about the "vector calculus gap" and offer realistic solutions to bridge the gap. The authors define the vector calculus gap as a disparity between the way mathematicians and physical scientists think about vectors, which they argue results in performance difficulties for students of physics and engineering. In this paper, they advocate emphasizing geometric reasoning over algebraic computation when introducing vectors. In addition, their proposed instructional method uses differentials to bridge the vector calculus gap. Included are sample group activities and tips for incorporating these ideas in the classroom. SEE RELATED ITEMS BELOW for a link to the authors' full web site on Bridging the Vector Calculus Gap.

Dray, Tevian; Manogue, Corinne A.

2008-12-23

185

Unoccupied orbital energies of 1,4-benzenedithiol and the HOMO–LUMO gap  

Microsoft Academic Search

The energies of the temporary anion states of 1,4-benzenedithiol (BDT) are determined by electron scattering and compared with those computed by density functional theory (DFT) and Hartree–Fock (HF) methods. Using semi-empirical scalings derived from the ionization energies and electron affinities of a series of phenyl–ethynyl compounds, we compute the HOMO–LUMO energy gap of BDT. We show that without such scalings

A. M. Scheer; G. A. Gallup; P. D. Burrow

2008-01-01

186

GAP Analysis Bulletin Number 15  

USGS Publications Warehouse

The Mission of the Gap Analysis Program (GAP) is to promote conservation by providing broad geographic information on biological diversity to resource managers, planners, and policy makers who can use the information to make informed decisions. As part of the National Biological Information Infrastructure (NBII) ?a collaborative program to provide increased access to data and information on the nation?s biological resources--GAP data and analytical tools have been used in hundreds of applications: from basic research to comprehensive state wildlife plans; from educational projects in schools to ecoregional assessments of biodiversity. The challenge: keeping common species common means protecting them BEFORE they become threatened. To do this on a state or regional basis requires key information such as land cover descriptions, predicted distribution maps for native animals, and an assessment of the level of protection currently given to those plants and animals. GAP works cooperatively with Federal, state, and local natural resource professionals and academics to provide this kind of information. GAP activities focus on the creation of state and regional databases and maps that depict patterns of land management, land cover, and biodiversity. These data can be used to identify ?gaps? in conservation--instances where an animal or plant community is not adequately represented on the existing network of conservation lands. GAP is administered through the U.S. Geological Survey. Through building partnerships among disparate groups, GAP hopes to foster the kind of collaboration that is needed to address conservation issues on a broad scale. For more information, contact: John Mosesso National GAP Director 703-648-4079 Kevin Gergely National GAP Operations Manager 208-885-3565

Maxwell, Jill, (Edited By); Gergely, Kevin; Aycrigg, Jocelyn; Canonico, Gabrielle; Davidson, Anne; Coffey, Nicole

2008-01-01

187

Anion binding behavior of heterocycle-strapped calix[4]pyrroles  

PubMed Central

A comparative study of the halide and benzoate anion binding properties of a series of phenyl, pyrrole, and furan-strapped calix[4]pyrroles has been carried out. These receptors, which have previously been shown to bind the chloride anion (Yoon et al., Angew. Chem., Int. Ed. 47(27):5038–5042, 2008), were found to bind bromide and benzoate anion (studied as the corresponding tetrabutyl-ammonium salts) with near equal affinity in acetonitrile, albeit less well than chloride, as determined from ITC measurements or NMR spectroscopic titrations. This stands in marked contrast to the parent octamethylcalix[4]pyrrole, where the carboxylate anion affinities are substantially higher than those for bromide anion under identical conditions. This finding is rationalized in terms of tighter binding cavity present in the strapped systems. For all three anions for which quantitative data could be obtained (i.e., Cl?, Br?, PhCO2?), the pyrrole-strapped system displayed the highest affinity, although the relative enhancement was found to depend on the anion in question. In the specific case of fluoride anion binding to the pyrrole-strapped receptor, two modes of interaction are inferred, with the first consisting of binding to the calix[4]pyrrole via NH-anion hydrogen bonds, followed by a process that involves deprotonation of the strapped pyrrolic NH proton. A single crystal X-ray diffraction analysis provides support for the first of these modes and further reveals the presence of a methanol molecule bound to the fluoride anion. PMID:21218134

Gross, Dustin E.; Yoon, Dae-Wi; Lynch, Vincent M.; Lee, Chang-Hee; Sessler, Jonathan L.

2010-01-01

188

Anion binding behavior of heterocycle-strapped calix[4]pyrroles.  

PubMed

A comparative study of the halide and benzoate anion binding properties of a series of phenyl, pyrrole, and furan-strapped calix[4]pyrroles has been carried out. These receptors, which have previously been shown to bind the chloride anion (Yoon et al., Angew. Chem., Int. Ed. 47(27):5038-5042, 2008), were found to bind bromide and benzoate anion (studied as the corresponding tetrabutyl-ammonium salts) with near equal affinity in acetonitrile, albeit less well than chloride, as determined from ITC measurements or NMR spectroscopic titrations. This stands in marked contrast to the parent octamethylcalix[4]pyrrole, where the carboxylate anion affinities are substantially higher than those for bromide anion under identical conditions. This finding is rationalized in terms of tighter binding cavity present in the strapped systems. For all three anions for which quantitative data could be obtained (i.e., Cl(-), Br(-), PhCO(2) (-)), the pyrrole-strapped system displayed the highest affinity, although the relative enhancement was found to depend on the anion in question. In the specific case of fluoride anion binding to the pyrrole-strapped receptor, two modes of interaction are inferred, with the first consisting of binding to the calix[4]pyrrole via NH-anion hydrogen bonds, followed by a process that involves deprotonation of the strapped pyrrolic NH proton. A single crystal X-ray diffraction analysis provides support for the first of these modes and further reveals the presence of a methanol molecule bound to the fluoride anion. PMID:21218134

Gross, Dustin E; Yoon, Dae-Wi; Lynch, Vincent M; Lee, Chang-Hee; Sessler, Jonathan L

2010-02-01

189

Fluorescent, Synthetic Amphiphilic Heptapeptide Anion Transporters  

PubMed Central

Synthetic anion transporters (SATs) of the general type (n-C18H37)2N-COCH2OCH2CO-(Gly)3-Pro-(Gly)3-O-n-C7H15, 1, are amphiphilic peptides that form anion-conducting pores in bilayer membranes. To better understand membrane insertion, assembly and aggregation dynamics, and membrane penetration, four novel fluorescent structures were prepared for use in both aqueous buffer and phospholipid bilayers. The fluorescent residues pyrene, indole, dansyl, and NBD were incorporated into 1 to give 2, 3, 4, and 5, respectively. Assembly of peptide amphiphiles in buffer was confirmed by monitoring changes in the pyrene monomer/excimer peaks observed for 2. Solvent-dependent fluorescence changes that were observed for indole (3) and dansyl (4) side-chained SATs in bilayers showed that these residues experienced an environment between ?=9 (CH2Cl2) and ?=24 (EtOH) in polarity. Fluorescence resonance energy transfer (FRET) between 2 and 3 demonstrated aggregation of SAT monomers within the bilayer. This self-assembly led to pore formation, which was detected as Cl- release from the liposomes. The results of acrylamide quenching of fluorescent SATs supported membrane insertion. Studies with NBD-labeled SAT 5 showed that peptide partition into the bilayer is relatively slow. Dithionite quenching of NBD-SATs suggests that the amphiphilic peptides are primarily in the bilayer’s outer leaflet. Images obtained by using a fluorescence microscope revealed membrane localization of a fluorescent SAT. Taken together, this study helps define the insertion, membrane localization, and aggregation behavior of this family of synthetic anion transporters in liposomal bilayers. PMID:18481800

You, Lei; Gokel, George W.

2008-01-01

190

Anion-exchange displacement centrifugal partition chromatography.  

PubMed

Ion-exchange displacement chromatography has been adapted to centrifugal partition chromatography. The use of an ionic liquid, benzalkonium chloride, as a strong anion-exchanger has proven to be efficient for the preparative separation of phenolic acid regioisomers. Multigram quantities of a mixture of three hydroxycinnamic acid isomers were separated using iodide as a displacer. The displacement process was characterized by a trapezoidal profile of analyte concentration in the eluate with narrow transition zones. By taking advantage of the partition rules involved in support-free liquid-liquid chromatography, a numerical separation model is proposed as a tool for preliminary process validation and further optimization. PMID:15516108

Maciuk, Alexandre; Renault, Jean-Hugues; Margraff, Rodolphe; Trébuchet, Philippe; Zèches-Hanrot, Monique; Nuzillard, Jean-Marc

2004-11-01

191

Anion adsorption induced reversal of coherency strain.  

SciTech Connect

Experimental results are presented for stress evolution, in vacuum and electrolyte, for the first monolayer of Cu on Au(111). In electrolyte the monolayer is pseudomorphic and the stress-thickness change is -0.60 N/m, while conventional epitaxy theory predicts a value of +7.76 N/m. In vacuum, the monolayer is incoherent with the underlying gold. Using a combination of first-principles based calculations and molecular dynamic simulations we analyzed these results and demonstrate that in electrolyte, overlayer coherency is maintained owing to anion adsorption.

Sieradzki, Karl (Arizona State University, Tempe. AZ); Thompson, C. V. (Massachusetts Inst. Tech., Cambridge, MA); Floro, Jerrold Anthony; Friesen, C. (Massachusetts Inst. Tech., Cambridge, MA); Tang, L. (Arizona State University, Tempe. AZ); Trimble, T. (Arizona State University, Tempe. AZ); Seel, Steven Craig; van Schilfgaarde, Mark (Arizona State University, Tempe. AZ); Dimitrov, Nikolay (Arizona State University, Tempe. AZ); Vasiljevic, Natasa (Arizona State University, Tempe. AZ)

2005-06-01

192

Probes for anionic cell surface detection  

DOEpatents

Embodiments of the present invention are generally directed to compositions comprising a class of molecular probes for detecting the presence of anionic cell surfaces. Embodiments include compositions that are enriched for these compositions and preparations, particularly preparations suitable for use as laboratory/clinical reagents and diagnostic indicators, either alone or as part of a kit. An embodiment of the invention provides for a highly selective agent useful in the discernment and identification of dead or dying cells, such as apoptotic cells, in a relatively calcium-free environment. An embodiment of the invention provides a selective agent for the identification of bacteria in a mixed population of bacterial cells and nonbacterial cells.

Smith, Bradley D.

2013-03-05

193

Electroculture for crop enhancement by air anions  

NASA Astrophysics Data System (ADS)

Electroculture, the practice of applying strong electric fields or other sources of small air ions to growing plants, has potential to markedly increase crop production and to speed crop growth. The considerable evidence for its effectiveness, and the studies of the mechanisms for its actions are discussed. A mild current of air anions (4 pA/cm2) stimulates bean crop growth and also earlier blossoming and increased growth in the annual, Exacum affine (Persian violet), as well as in seedling geraniums. The present results would indicate that the growing period required until the plants reach a saleable stage of maturity can be shortened by about two weeks under greenhouse conditions.

Pohl, H. A.; Todd, G. W.

1981-12-01

194

Pneumatic gap sensor and method  

SciTech Connect

An apparatus and method for monitoring and maintaining a predetermined width in the gap between a casting nozzle and a casting wheel, wherein the gap is monitored by means of at least one pneumatic gap sensor. The pneumatic gap sensor is mounted on the casting nozzle in proximity to the casting surface and is connected by means of a tube to a regulator and a transducer. The regulator provides a flow of gas through a restictor to the pneumatic gap sensor, and the transducer translates the changes in the gas pressure caused by the proximity of the casting wheel to the pneumatic gap sensor outlet into a signal intelligible to a control device. The relative positions of the casting nozzle and casting wheel can thereby be selectively adjusted to continually maintain a predetermined distance between their adjacent surfaces. The apparatus and method enables accurate monitoring of the actual casting gap in a simple and reliable manner resistant to the extreme temperatures and otherwise hostile casting environment.

Bagdal, Karl T. (Middletown, OH); King, Edward L. (Trenton, OH); Follstaedt, Donald W. (Middletown, OH)

1992-01-01

195

Pneumatic gap sensor and method  

DOEpatents

An apparatus and method for monitoring and maintaining a predetermined width in the gap between a casting nozzle and a casting wheel, wherein the gap is monitored by means of at least one pneumatic gap sensor. The pneumatic gap sensor is mounted on the casting nozzle in proximity to the casting surface and is connected by means of a tube to a regulator and a transducer. The regulator provides a flow of gas through a restictor to the pneumatic gap sensor, and the transducer translates the changes in the gas pressure caused by the proximity of the casting wheel to the pneumatic gap sensor outlet into a signal intelligible to a control device. The relative positions of the casting nozzle and casting wheel can thereby be selectively adjusted to continually maintain a predetermined distance between their adjacent surfaces. The apparatus and method enables accurate monitoring of the actual casting gap in a simple and reliable manner resistant to the extreme temperatures and otherwise hostile casting environment. 6 figs.

Bagdal, K.T.; King, E.L.; Follstaedt, D.W.

1992-03-03

196

Process for removing sulfate anions from waste water  

DOEpatents

A liquid emulsion membrane process for removing sulfate anions from waste water is disclosed. The liquid emulsion membrane process includes the steps of: (a) providing a liquid emulsion formed from an aqueous strip solution and an organic phase that contains an extractant capable of removing sulfate anions from waste water; (b) dispersing the liquid emulsion in globule form into a quantity of waste water containing sulfate anions to allow the organic phase in each globule of the emulsion to extract and absorb sulfate anions from the waste water and (c) separating the emulsion including its organic phase and absorbed sulfate anions from the waste water to provide waste water containing substantially no sulfate anions.

Nilsen, David N. (Lebanon, OR); Galvan, Gloria J. (Albany, OR); Hundley, Gary L. (Corvallis, OR); Wright, John B. (Albany, OR)

1997-01-01

197

Preorganized anion traps for exploiting anion-? interactions: an experimental and computational study.  

PubMed

1,3-Bis(pentafluorophenyl-imino)isoindoline (A(F)) and 3,6-di-tert-butyl-1,8-bis(pentafluorophenyl)-9H-carbazole (B(F)) have been designed as preorganized anion receptors that exploit anion-? interactions, and their ability to bind chloride and bromide in various solvents has been evaluated. Both receptors A(F) and B(F) are neutral but provide a central NH hydrogen bond that directs the halide anion into a preorganized clamp of the two electron-deficient appended arenes. Crystal structures of host-guest complexes of A(F) with DMSO, Cl(-), or Br(-) (A(F):DMSO, A(F):Cl(-), and A(2)(F):Br(-)) reveal that in all cases the guest is located in the cleft between the perfluorinated flaps, but NMR spectroscopy shows a more complex situation in solution because of E,Z/Z,Z isomerism of the host. In the case of the more rigid receptor B(F), Job plots evidence 1:1 complex formation with Cl(-) and Br(-), and association constants up to 960 M(-1) have been determined depending on the solvent. Crystal structures of B(F) and B(F):DMSO visualize the distinct preorganization of the host for anion-? interactions. The reference compounds 1,3-bis(2-pyrimidylimino)isoindoline (A(N)) and 3,6-di-tert-butyl-1,8-diphenyl-9H-carbazole (B(H)), which lack the perfluorinated flaps, do not show any indication of anion binding under the same conditions. A detailed computational analysis of the receptors A(F) and B(F) and their host-guest complexes with Cl(-) or Br(-) was carried out to quantify the interactions in play. Local correlation methods were applied, allowing for a decomposition of the ring-anion interactions. The latter were found to contribute significantly to the stabilization of these complexes (about half of the total energy). Compounds A(F) and B(F) represent rare examples of neutral receptors that are well preorganized for exploiting anion-? interactions, and rare examples of receptors for which the individual contributions to the binding energy have been quantified. PMID:24307361

Bretschneider, Anne; Andrada, Diego M; Dechert, Sebastian; Meyer, Steffen; Mata, Ricardo A; Meyer, Franc

2013-12-01

198

Deuterium anions in inertial electrostatic confinement devices.  

PubMed

A magnetic deflection-energy analyzer and Faraday trap diagnostic have been used to make measurements of divergent deuterium anion flow in the inertial electrostatic confinement experiment at the University of Wisconsin-Madison (UW-IEC) [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, I. E. Radel, and A. L. Wehmeyer, Fusion Sci. Technol. 47, 1238 (2005)], a device to confine high-energy light ions in a spherically symmetric electrostatic potential well. Deuterium anion current densities as high as 8.5 microA/cm2 have been measured at the wall of the UW-IEC device, 40 cm from the surface of the device cathode with a detector assembly of admittance area 0.7 cm2. Energy spectra obtained using a magnetic deflection-energy analyzer diagnostic indicate the presence of D2(-), and D- ions produced through thermal electron attachment near the device cathode, as well as D- ions produced via charge-transfer processes between the anode and cathode of the device. PMID:19905231

Boris, D R; Alderson, E; Becerra, G; Donovan, D C; Egle, B; Emmert, G A; Garrison, L; Kulcinski, G L; Santarius, J F; Schuff, C; Zenobia, S J

2009-09-01

199

Anionic derivatives of uracil: fragmentation and reactivity.  

PubMed

Uracil is an essential biomolecule for terrestrial life, yet its prebiotic formation mechanisms have proven elusive for decades. Meteorites have been shown to contain uracil and the interstellar abundance of aromatic species and nitrogen-containing molecules is well established, providing support for uracil's presence in the interstellar medium (ISM). The ion chemistry of uracil may provide clues to its prebiotic synthesis and role in the origin of life. The fragmentation of biomolecules provides valuable insights into their formation. Previous research focused primarily on the fragmentation and reactivity of cations derived from uracil. In this study, we explore deprotonated uracil-5-carboxylic acid and its anionic fragments to elucidate novel reagents of uracil formation and to characterize the reactivity of uracil's anionic derivatives. The structures of these fragments are identified through theoretical calculations, further fragmentation, experimental acidity bracketing, and reactivity with several detected and potential interstellar species (SO2, OCS, CS2, NO, N2O, CO, NH3, O2, and C2H4). Fragmentation is achieved through collision induced dissociation (CID) in a commercial ion trap mass spectrometer, and all reaction rate constants are measured using a modification of this instrument. Experimental data are supported by theoretical calculations at the B3LYP/6-311++G(d,p) level of theory. Lastly, the astrochemical implications of the observed fragmentation and reaction processes are discussed. PMID:25036757

Cole, Callie A; Wang, Zhe-Chen; Snow, Theodore P; Bierbaum, Veronica M

2014-09-01

200

Systems Genetics of Mineral Metabolism123  

PubMed Central

Minerals are essential and toxic elements that have an impact on human health. Although we have learned a tremendous amount about the metabolism, biological roles, and health effects of minerals with the tools of biochemistry, cell biology, and molecular genetics, there are gaps in our knowledge of mineral biology that will benefit from new approaches. Forward genetics, whereby variations in phenotypes are mapped to natural genetic variation in the genome, has been successfully used to increase our understanding of many biologically important traits but has not yet been used extensively for mineral metabolism. In addition, the well-appreciated existence of interactions between minerals justifies a broader, systems approach to the study of mineral metabolism, i.e., ionomics. This short review will explain the value of forward genetics and ionomics as tools for exploring mammalian mineral metabolism. PMID:21270371

Fleet, James C.; Replogle, Rebecca; Salt, David E.

2011-01-01

201

Unexpectedly strong anion-? interactions on the graphene flakes.  

PubMed

Interactions of anions with simple aromatic compounds have received growing attention due to their relevancy in various fields. Yet, the anion-? interactions are generally very weak, for example, there is no favorable anion-? interaction for the halide anion F(-) on the simplest benzene surface unless the H-atoms are substituted by the highly negatively charged F. In this article, we report a type of particularly strong anion-? interactions by investigating the adsorptions of three halide anions, that is, F(-), Cl(-), and Br(-), on the hydrogenated-graphene flake using the density functional theory. The anion-? interactions on the graphene flake are shown to be unexpectedly strong compared to those on simple aromatic compounds, for example, the F(-)-adsorption energy is as large as 17.5 kcal/mol on a graphene flake (C(84) H(24)) and 23.5 kcal/mol in the periodic boundary condition model calculations on a graphene flake C(113) (the supercell containing a F(-) ion and 113 carbon atoms). The unexpectedly large adsorption energies of the halide anions on the graphene flake are ascribed to the effective donor-acceptor interactions between the halide anions and the graphene flake. These findings on the presence of very strong anion-? interactions between halide ions and the graphene flake, which are disclosed for the first time, are hoped to strengthen scientific understanding of the chemical and physical characteristics of the graphene in an electrolyte solution. These favorable interactions of anions with electron-deficient graphene flakes may be applicable to the design of a new family of neutral anion receptors and detectors. PMID:22430486

Shi, Guosheng; Ding, Yihong; Fang, Haiping

2012-05-30

202

Anion binding behavior of heterocycle-strapped calix[4]pyrroles  

Microsoft Academic Search

A comparative study of the halide and benzoate anion binding properties of a series of phenyl, pyrrole, and furan-strapped\\u000a calix[4]pyrroles has been carried out. These receptors, which have previously been shown to bind the chloride anion (Yoon\\u000a et al., Angew. Chem., Int. Ed. 47(27):5038–5042, 2008), were found to bind bromide and benzoate anion (studied as the corresponding\\u000a tetrabutylammonium salts) with

Dustin E. Gross; Dae-Wi Yoon; Vincent M. Lynch; Chang-Hee Lee; Jonathan L. Sessler

2010-01-01

203

Multinuclear NMR investigation of the formation of aluminosilicate anions  

Microsoft Academic Search

The structure of simple aluminosilicate anions formed by the reaction of silicate and aluminate anions was investigated by ²⁹Si and ²⁷Al NMR spectroscopy. The extent of aluminosilicate formation was found to increase with increasing silicate ratio and increasing cation size. The first of these trends is attributed to the redistribution of Si with increasing silicate ratio to more acidic anions.

A. V. McCormick; A. T. Bell; C. J. Radke

1989-01-01

204

Isolation of a carborane-fused triazole radical anion.  

PubMed

Outside the cage: A change in the redox properties of a triazole fused to a carborane anion through methylation to form a zwitterion enabled facile chemical reduction of the compound to an isolable triazole radical anion (see structure: C gray, H white, N blue, B brown, Cl green). The radical anion is stabilized by kinetic protection by the chlorinated carborane and the delocalization of spin density throughout the exo-cluster ??system. PMID:24106045

Asay, Matthew; Kefalidis, Christos E; Estrada, Jess; Weinberger, David S; Wright, James; Moore, Curtis E; Rheingold, Arnold L; Maron, Laurent; Lavallo, Vincent

2013-10-25

205

The mechanism of anion permeation in thorium-treated gallbladder  

Microsoft Academic Search

Summary Polyvalent cations (such as Ca+2, La+3, and Th+4) and low pH shift the permeability of some biological membranes from preferentially cation-permeable towards preferentially anion-permeable. The action of Th+4 on permselectivity, and the anion permeation mechanism it produces, have been studied in rabbit gallbladder epithelium. The effect involves both a suppression of cation conductance and an increase of anion conductance.

Terry E. Machen; Jared M. Diamond

1972-01-01

206

ACTION OF SYNTHETIC DETERGENTS ON THE METABOLISM OF BACTERIA  

PubMed Central

A study of the effects of synthetic detergents and wetting agents on respiration and glycolysis of Gram-positive and Gram-negative microorganisms has led to the following conclusions. 1. All the cationic detergents studied are very effective inhibitors of bacterial metabolism at 1:3000 concentration, and several are equally active at 1:30,000. Few of the anionic detergents inhibit as effectively as the cationic compounds. 2. Gram-positive and Gram-negative microorganisms are equally sensitive to the action of the cationic detergents. On the other hand, all the anionic detergents included in our studies selectively inhibit the metabolism of Gram-positive microorganisms. 3. The inhibitory action of both types of detergents is influenced markedly by hydrogen ion concentration. Cationic detergents exhibit their maximum activity in the alkaline pH range, and the anionic, in the acid range. 4. Studies of homologous series of straight chain alkyl sulfates and sulfoacetates (C8 to C18) demonstrate that maximum inhibition is exerted by the 12, 14, and 16 carbon compounds (lauryl, myristyl, and cetyl). 5. It has been observed that three lauryl esters of amino acids are powerful inhibitors of bacterial metabolism. To our knowledge, the effects on bacterial metabolism of such cationic detergents (without the quaternary ammonium structure) have not been studied previously. Our results demonstrate that other cationic detergents can exhibit an inhibitory activity comparable to quaternary ammonium compounds. 6. Certain detergents stimulate bacterial metabolism at concentrations lower than the inhibiting values. This effect has been found more frequently among the anionic detergents. PMID:19871076

Baker, Zelma; Harrison, R. W.; Miller, Benjamin F.

1941-01-01

207

Anionic Salt Programs for Close-Up Dry Cows  

E-print Network

chloride and sulfur are considered to greatly influ- ence the acid-base status in the body. The dietary cation-anion difference (DCAD) concept quantifies the major cations and anions in diets. A negative DCAD diet contains more equivalents of anions than... in milliequivalents per 100-gram ration of dry matter, use the following formula: [(% sodium/0.023) + (% potassium/0.039)] ? [(% chloride/0.0355) + (% sulfur/0.016)] A ration using typical forages and concentrates generally has a positive DCAD. Adding anionic salts...

Stokes, Sandra R.

1998-12-17

208

Organic anion transporting polypeptide 1c1 structure and function.  

E-print Network

??Organic anion transporting polypeptides (Oatps) are solute carrier family members that exhibit marked evolutionary conservation. Mammalian Oatps exhibit wide tissue expression with an emphasis on… (more)

Westholm, Daniel Eric

2009-01-01

209

STRUCTURAL REQUIREMENTS OF ORGANIC ANION TRANSPORTING POLYPEPTIDE MEDIATED TRANSPORT.  

E-print Network

??The organic anion transporting polypeptides (human: OATP; other: Oatp) form a mammalian transporter superfamily that mediates the transport of structurally unrelated compounds across the cell… (more)

Weaver, Yi Miao

2010-01-01

210

Recognition of Chiral Carboxylic Anions by Artificial Receptors  

PubMed Central

Many carboxylic molecules, ranging from drugs to flavors and fragrances, contain chiral centers. As a consequence, research has been carried out in order to design and synthesize artificial receptors for carboxylic anions. Many problems have to be solved for binding anions. The results obtained in the binding of carboxylic anions by guanidine, secondary ammonium and metal-center have been selected. The last part of this review focuses on chiral recognition of carboxylic anions by organic and metal-based chiral receptors. PMID:20957098

Dieng, Pape Sylla; Sirlin, Claude

2010-01-01

211

Electronic materials with a wide band gap: recent developments  

PubMed Central

The development of semiconductor electronics is reviewed briefly, beginning with the development of germanium devices (band gap E g = 0.66?eV) after World War II. A tendency towards alternative materials with wider band gaps quickly became apparent, starting with silicon (E g = 1.12?eV). This improved the signal-to-noise ratio for classical electronic applications. Both semiconductors have a tetrahedral coordination, and by isoelectronic alternative replacement of Ge or Si with carbon or various anions and cations, other semiconductors with wider E g were obtained. These are transparent to visible light and belong to the group of wide band gap semiconductors. Nowadays, some nitrides, especially GaN and AlN, are the most important materials for optical emission in the ultraviolet and blue regions. Oxide crystals, such as ZnO and ?-Ga2O3, offer similarly good electronic properties but still suffer from significant difficulties in obtaining stable and technologically adequate p-type conductivity. PMID:25295170

Klimm, Detlef

2014-01-01

212

Sodium Bicarbonate Therapy in Patients with Metabolic Acidosis  

PubMed Central

Metabolic acidosis occurs when a relative accumulation of plasma anions in excess of cations reduces plasma pH. Replacement of sodium bicarbonate to patients with sodium bicarbonate loss due to diarrhea or renal proximal tubular acidosis is useful, but there is no definite evidence that sodium bicarbonate administration to patients with acute metabolic acidosis, including diabetic ketoacidosis, lactic acidosis, septic shock, intraoperative metabolic acidosis, or cardiac arrest, is beneficial regarding clinical outcomes or mortality rate. Patients with advanced chronic kidney disease usually show metabolic acidosis due to increased unmeasured anions and hyperchloremia. It has been suggested that metabolic acidosis might have a negative impact on progression of kidney dysfunction and that sodium bicarbonate administration might attenuate this effect, but further evaluation is required to validate such a renoprotective strategy. Sodium bicarbonate is the predominant buffer used in dialysis fluids and patients on maintenance dialysis are subjected to a load of sodium bicarbonate during the sessions, suffering a transient metabolic alkalosis of variable severity. Side effects associated with sodium bicarbonate therapy include hypercapnia, hypokalemia, ionized hypocalcemia, and QTc interval prolongation. The potential impact of regular sodium bicarbonate therapy on worsening vascular calcifications in patients with chronic kidney disease has been insufficiently investigated.

Adeva-Andany, Maria M.; Fernandez-Fernandez, Carlos; Mourino-Bayolo, David; Castro-Quintela, Elvira; Dominguez-Montero, Alberto

2014-01-01

213

Observation of polychromatic gap solitons  

E-print Network

theoretically and observe experimentally poly- chromatic gap solitons generated by supercontinuum light-induced broadening and color separation to the simultaneous spatio-spectral localization of supercontinuum light. Kivshar, "Controlled generation and stee

214

Why Metabolic Syndrome Matters  

MedlinePLUS

Why Metabolic Syndrome Matters Updated:Jul 24,2014 Metabolic syndrome may be diagnosed when a patient has a cluster of risk factors for ... Syndrome • Home • About Metabolic Syndrome • Why Metabolic Syndrome Matters • Your Risk for Metabolic Syndrome • Symptoms & Diagnosis • Prevention & ...

215

Gap-Definable Counting Classes  

Microsoft Academic Search

The function class #P lacks an important closure property: it is not closed under subtraction.To remedy this problem, we introduce the function class GapP as a natural alternative to #P.GapP is the closure of #P under subtraction, and has all the other useful closure propertiesof #P as well. We show that most previously studied counting classes, including PP, C=P,and Mod

Stephen A. Fenner; Lance J. Fortnowt; Stuart A. Kurtz

1991-01-01

216

Eight electrode optical readout gap  

DOEpatents

A protective device for a plurality of electrical circuits includes a pluity of isolated electrodes forming a gap with a common electrode. An output signal, electrically isolated from the circuits being monitored, is obtained by a photosensor viewing the discharge gap through an optical window. Radioactive stabilization of discharge characteristics is provided for slowly changing voltages and carbon tipped dynamic starters provide desirable discharge characteristics for rapidly varying voltages. A hydrogen permeation barrier is provided on external surfaces of the device.

Boettcher, Gordon E. (Albuquerque, NM); Crain, Robert W. (Albuquerque, NM)

1985-01-01

217

Eight electrode optical readout gap  

DOEpatents

A protective device for a plurality of electrical circuits includes a plurality of isolated electrodes forming a gap with a common electrode. An output signal, electrically isolated from the circuits being monitored, is obtained by a photosensor viewing the discharge gap through an optical window. Radioactive stabilization of discharge characteristics is provided for slowly changing voltages and carbon tipped dynamic starters provide desirable discharge characteristics for rapidly varying voltages. A hydrogen permeation barrier is provided on external surfaces of the device.

Boettcher, G.E.; Crain, R.W.

1984-01-01

218

GRADE GAP/FUTURE GAP: ADDRESSING RACIAL DISPARITIES IN L&S INTRODUCTORY COURSES  

E-print Network

1 GRADE GAP/FUTURE GAP: ADDRESSING RACIAL DISPARITIES IN L&S INTRODUCTORY COURSES Report ........................................................................................................................................................................ 3 RECOMMENDATIONS: ELIMINATE THE GRADE GAP IN KEY INTRODUCTORY COURSES BY 2014............. 4.................................................................................................................................................. 5 THE GRADE GAP IN KEY INTRODUCTORY COURSES

Sheridan, Jennifer

219

Synthetic ion transporters that work with anion-? interactions, halogen bonds, and anion-macrodipole interactions.  

PubMed

The transport of ions and molecules across lipid bilayer membranes connects cells and cellular compartments with their environment. This biological process is central to a host of functions including signal transduction in neurons and the olfactory and gustatory sensing systems, the translocation of biosynthetic intermediates and products, and the uptake of nutrients, drugs, and probes. Biological transport systems are highly regulated and selectively respond to a broad range of physical and chemical stimulation. A large percentage of today's drugs and many antimicrobial or antifungal agents take advantage of these systems. Other biological transport systems are highly toxic, such as the anthrax toxin or melittin from bee venom. For more than three decades, organic and supramolecular chemists have been interested in developing new transport systems. Over time, curiosity about the basic design has evolved toward developing of responsive systems with applications in materials sciences and medicine. Our early contributions to this field focused on the introduction of new structural motifs with emphasis on rigid-rod scaffolds, artificial ?-barrels, or ?-stacks. Using these scaffolds, we have constructed selective systems that respond to voltage, pH, ligands, inhibitors, or light (multifunctional photosystems). We have described sensing applications that cover the three primary principles of sensor development: immunosensors that use aptamers, biosensors (an "artificial" tongue), and differential sensors (an "artificial" nose). In this Account, we focus on our recent interest in applying synthetic transport systems as analytical tools to identify the functional relevance of less common noncovalent interactions, anion-? interactions, halogen bonds, and anion-macrodipole interactions. Anion-? interactions, the poorly explored counterpart of cation-? interactions, occur in aromatic systems with a positive quadrupole moment, such as TNT or hexafluorobenzene. To observe these elusive interactions in action, we synthesized naphthalenediimide transporters of increasing ?-acidity up to an unprecedented quadrupole moment of +39 Buckinghams and characterized these systems in comparison with tandem mass spectrometry and computational simulations. With ?-acidic calixarenes and calixpyrroles, we have validated our results on anion-? interactions and initiated our studies of halogen bonds. Halogen bonds originate from the ?-hole that appears on top of electron-deficient iodines, bromines, and chlorines. Halogen-bond donors are ideal for anion transport because they are as strong and at least as directional as hydrogen-bond donors, but also hydrophobic. The discovery of the smallest possible organic anion transporter, trifluoroiodomethane, illustrates the power of halogen-bond donors. This molecule contains a single carbon atom and is a gas with a boiling point of -22 °C. Anion-macrodipole interactions, finally, differ significantly from anion-? interactions and halogen bonds because they are important in nature and cannot be studied with small molecules. We have used anion-transporting peptide/urea nanotubes to examine these interactions in synthetic transport systems. To facilitate the understanding of the described results, we also include an in-depth discussion of the meaning of Hill coefficients. The use of synthetic transport systems to catch less common noncovalent interactions at work is important because it helps to expand the collection of interactions available to create functional systems. Progress in this direction furthers fundamental knowledge and invites many different applications. For illustration, we briefly discuss how this knowledge could apply to the development of new catalysts. PMID:23547885

Vargas Jentzsch, Andreas; Hennig, Andreas; Mareda, Jiri; Matile, Stefan

2013-12-17

220

Production of bulk chemicals via novel metabolic pathways in microorganisms.  

PubMed

Metabolic engineering has been playing important roles in developing high performance microorganisms capable of producing various chemicals and materials from renewable biomass in a sustainable manner. Synthetic and systems biology are also contributing significantly to the creation of novel pathways and the whole cell-wide optimization of metabolic performance, respectively. In order to expand the spectrum of chemicals that can be produced biotechnologically, it is necessary to broaden the metabolic capacities of microorganisms. Expanding the metabolic pathways for biosynthesizing the target chemicals requires not only the enumeration of a series of known enzymes, but also the identification of biochemical gaps whose corresponding enzymes might not actually exist in nature; this issue is the focus of this paper. First, pathway prediction tools, effectively combining reactions that lead to the production of a target chemical, are analyzed in terms of logics representing chemical information, and designing and ranking the proposed metabolic pathways. Then, several approaches for potentially filling in the gaps of the novel metabolic pathway are suggested along with relevant examples, including the use of promiscuous enzymes that flexibly utilize different substrates, design of novel enzymes for non-natural reactions, and exploration of hypothetical proteins. Finally, strain optimization by systems metabolic engineering in the context of novel metabolic pathways constructed is briefly described. It is hoped that this review paper will provide logical ways of efficiently utilizing 'big' biological data to design and develop novel metabolic pathways for the production of various bulk chemicals that are currently produced from fossil resources. PMID:23280013

Shin, Jae Ho; Kim, Hyun Uk; Kim, Dong In; Lee, Sang Yup

2013-11-01

221

Living anionic polymerization using a microfluidic reactor  

SciTech Connect

Living anionic polymerizations were conducted within aluminum-polyimide microfluidic devices. Polymerizations of styrene in cyclohexane were carried out at various conditions, including elevated temperature (60 °C) and high monomer concentration (42%, by volume). The reactions were safely maintained at a controlled temperature at all points in the reactor. Conducting these reactions in a batch reactor results in uncontrolled heat generation with potentially dangerous rises in pressure. Moreover, the microfluidic nature of these devices allows for flexible 2D designing of the flow channel. Four flow designs were examined (straight, periodically pinched, obtuse zigzag, and acute zigzag channels). The ability to use the channel pattern to increase the level of mixing throughout the reactor was evaluated. When moderately high molecular mass polymers with increased viscosity were made, the patterned channels produced polymers with narrower PDI, indicating that passive mixing arising from the channel design is improving the reaction conditions.

Iida, Kazunori; Chastek, Thomas Q.; Beers, Kathryn L.; Cavicchi, Kevin A.; Chun, Jaehun; Fasolka, Michael J.

2009-02-01

222

Advanced polymer chemistry of organometallic anions  

SciTech Connect

This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of the project was to prepare and characterize new polymers incorporating cobalt dicarbollide. Specific goals were to prepare polymerizable cobalt dicarbollide monomers using the nucleophilic substitution route discovered in laboratories and to establish the reaction conditions required to form polymers from these complexes. This one-year project resulted in two publications (in press), and provided the foundation for further investigations into polymer synthesis and characterization using cobalt dicarbollide and other metallocarboranes. Interest in synthesizing organometallic polymers containing the cobalt bis(dicarbollide) anion is motivated by their possible application as cation exchange materials for the remediation of cesium-137 and strontium-90 from nuclear wastes.

Chamberlin, R.M.; Abney, K.D. [Los Alamos National Lab., NM (United States); Balaich, G.J.; Fino, S.A. [Air Force Academy, CO (United States)

1997-11-01

223

Bimetallic anionic formyl complexes: synthesis and properties  

SciTech Connect

Three bimetallic anionic complexes, (2) lithium + dimanganese nonacarbonyl formyl/sup -/, (3) lithium + rhenium manganese nonacarbonyl formyl/sup -/, and (4) lithium + cisdirhenium nonacarbonyl formyl, are prepared by the reaction of lithium triethylboron hydride with the corresponding neutral metal carbonyl dimers, dimanganese decacarbonyl and manganese rhenium decarbonyl. 2 has a half-life of ca 8 min at room temperature, 4 is stable for days and is easily isolated as a tetrahydrofuran solvate. When 2 - 4 are treated with electrophiles such as benzaldehyde, iron pentacarbonyl, n-octyl iodide, hydride transfer occurs to produce benzyl alcohol, lithium + iron tetracarbonyl formyl/sup -/ complex, and octane, respectively. 3 is the weakest hydride donor. Reaction of 4 with methyl iodide produces ca 52% methane. The only identifiable product from the pyrolysis of 4 is dirhenium decacarbonyl; photolysis of 4 produces lithium + dirhenium nonacarbonyl hydride. 1 figure.

Tam, W.; Marsi, M.; Gladysz, J.A.

1983-05-11

224

Organic anions and the diarrhea of inflammatory bowel disease  

Microsoft Academic Search

To determine if organic anions contribute to the diarrhea of inflammatory bowel disease, we measured osmolality, electrolytes, short-chain fatty acids, lactic acid, and some Krebs cycle anions in 24-hr fecal collections from 18 patients with chronic ulcerative colitis, 20 with Crohn's disease of the colon, and 16 normals. Mean lactic acid concentration was significantly elevated in ulcerative and Crohn's colitis,

P. Vernia; A. Gnaedinger; W. Hauck; R. I. Breuer

1988-01-01

225

Calix[n]phyrins: Synthesis and Anion Recognition  

NASA Astrophysics Data System (ADS)

This chapter covers advances in calix[n]phyrin chemistry since 2001, focusing on their synthesis and properties as anion complexants. Over the last 8 years, the structural variety of calixphyrins has significantly increased, and several applications as anion complexants were reported.

Dehaen, Wim

226

Biological activity and environmental impact of anionic surfactants  

Microsoft Academic Search

The newest results concerning the biological activity and environmental fate of anionic surfactants are collected and critically evaluated. The chemical and physicochemical parameters related to the biological activity and the field of application are briefly discussed. Examples on the effect of anionic surfactants on the cell membranes, on the activity of enzymes, on the binding to various proteins and to

Tibor Cserháti; Esther Forgács; Gyula Oros

2002-01-01

227

Ab initio electronic structure of HCN dipole-bound anions  

E-print Network

: 10.1063/1.1358863 I. INTRODUCTION A. Anions of hydrogen cyanide and isocyanide Hydrogen cyanide HCN of cyanide doped alkali halide crystals and obtained the infrared spectrum of this anion, while Tsuda and co attempts under- taken to estimate the electron affinity EA of hydrogen cyanide.7­9 Pacansky et al.,7

Simons, Jack

228

Extraction of monoclonal antibodies (IgG1) using anionic and anionic/nonionic reverse micelles.  

PubMed

Purification schemes for antibody production based on affinity chromatography are trying to keep pace with increases in cell culture expression levels and many current research initiatives are focused on finding alternatives to chromatography for the purification of Monoclonal antibodies (MAbs). In this article, we have investigated an alternative separation technique based on liquid-liquid extraction called the reverse micellar extraction. We extracted MAb (IgG1) using reverse micelles of an anionic surfactant, sodium bis 2-ethyl-hexyl sulfosuccinate (AOT) and a combination of anionic (AOT) and nonionic surfactants (Brij-30, Tween-85, Span-85) using isooctane as the solvent system. The extraction efficiency of IgG1 was studied by varying parameters, such as pH of the aqueous phase, cation concentration, and type and surfactant concentration. Using the AOT/Isooctane reverse micellar system, we could achieve good overall extraction of IgG1 (between 80 and 90%), but only 30% of the bioactivity of IgG1 could be recovered at the end of the extraction by using its binding to affinity chromatography columns as a surrogate measure of activity. As anionic surfactants were suspected as being one of the reasons for the reduced activity, we decided to combine a nonionic surfactant with an anionic surfactant and then study its effect on the extraction efficiency and bioactivity. The best results were obtained using an AOT/Brij-30/Isooctane reverse micellar system, which gave an overall extraction above 90 and 59% overall activity recovery. An AOT/Tween-85/Isooctane reverse micellar system gave an overall extraction of between 75 and 80% and overall activity recovery of around 40-45%. The results showed that the activity recovery of IgG1 can be significantly enhanced using different surfactant combination systems, and if the recovery of IgG1 can be further enhanced, the technique shows considerable promise for the downstream purification of MAbs. PMID:20665658

George, Daliya A; Stuckey, David C

2010-01-01

229

Permeability of homotypic and heterotypic gap junction channels formed of cardiac connexins mCx30.2, Cx40, Cx43, and Cx45  

PubMed Central

We examined the permeabilities of homotypic and heterotypic gap junction (GJ) channels formed of rodent connexins (Cx) 30.2, 40, 43, and 45, which are expressed in the heart and other tissues, using fluorescent dyes differing in net charge and molecular mass. Combining fluorescent imaging and electrophysiological recordings in the same cell pairs, we evaluated the single-channel permeability (P?). All homotypic channels were permeable to the anionic monovalent dye Alexa Fluor-350 (AF350), but mCx30.2 channels exhibited a significantly lower P? than the others. The anionic divalent dye Lucifer yellow (LY) remained permeant in Cx40, Cx43, and Cx45 channels, but transfer through mCx30.2 channels was not detected. Heterotypic channels generally exhibited P? values that were intermediate to the corresponding homotypic channels. P? values of mCx30.2/Cx40, mCx30.2/Cx43, or mCx30.2/Cx45 heterotypic channels for AF350 were similar and approximately twofold higher than P? values of mCx30.2 homotypic channels. Permeabilities for cationic dyes were assessed only qualitatively because of their binding to nucleic acids. All homotypic and heterotypic channel configurations were permeable to ethidium bromide and 4,6-diamidino-2-phenylindole. Permeability for propidium iodide was limited only for GJ channels that contain at least one mCx30.2 hemichannel. In summary, we have demonstrated that Cx40, Cx43, and Cx45 are permeant to all examined cationic and anionic dyes, whereas mCx30.2 demonstrates permeation restrictions for molecules with molecular mass over ?400 Da. The ratio of single-channel conductance to permeability for AF350 was ?40- to 170-fold higher for mCx30.2 than for Cx40, Cx43, and Cx45, suggesting that mCx30.2 GJs are notably more adapted to perform electrical rather than metabolic cell-cell communication. PMID:17557922

Rackauskas, Mindaugas; Verselis, Vytas K.; Bukauskas, Feliksas F.

2010-01-01

230

The Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance  

SciTech Connect

Work at carried out at ORNL since the inception of the project has served to demonstrate that the calix[4]pyrroles from the co-P.I.'s laboratory at the Univ. of Texas strongly enhance the extraction of sulfate by tricaprylmethylammonium nitrate or chloride in the presence of excess nitrate and chloride. Similar results were found in the case of the tetraamide macrocycles synthesized in the Bowman-James laboratory (Univ. of Kansas). Effort at the Univ. of Texas thus focused on generating new pyrrole-amide macrocycles that might combine the most favorable aspects of the calixpyrroles and the tetraamides. This culminated in the synthesis of several new receptors, which provided a ''matched set'' from whence insights into anion recognition could be inferred. As can be inferred from the data summarized in Table 1, small adjustments in the structure allow for a fine-tuning of the anion binding properties in favor of sulfate recognition, or in the case of injudicious modifications, selectivities that favor completely different classes of anionic substrates.

Sessler, Jonathan L.

2005-06-01

231

Field induced gap infrared detector  

NASA Technical Reports Server (NTRS)

A tunable infrared detector which employs a vanishing band gap semimetal material provided with an induced band gap by a magnetic field to allow intrinsic semiconductor type infrared detection capabilities is disclosed. The semimetal material may thus operate as a semiconductor type detector with a wavelength sensitivity corresponding to the induced band gap in a preferred embodiment of a diode structure. Preferred semimetal materials include Hg(1-x)Cd(x)Te, x is less than 0.15, HgCdSe, BiSb, alpha-Sn, HgMgTe, HgMnTe, HgZnTe, HgMnSe, HgMgSe, and HgZnSe. The magnetic field induces a band gap in the semimetal material proportional to the strength of the magnetic field allowing tunable detection cutoff wavelengths. For an applied magnetic field from 5 to 10 tesla, the wavelength detection cutoff will be in the range of 20 to 50 micrometers for Hg(1-x)Cd(x)Te alloys with x about 0.15. A similar approach may also be employed to generate infrared energy in a desired band gap and then operating the structure in a light emitting diode or semiconductor laser type of configuration.

Elliott, C. Thomas (inventor)

1990-01-01

232

Selectivity Control in Synergistic Liquid-Liquid Anion Exchange of Univalent Anions via Structure-Specific Cooperativity between Quaternary Ammonium Cations and Anion Receptors  

SciTech Connect

Two anion receptors enhance liquid-liquid anion exchange when added to quaternary alkylammonium chloride anion exchangers, but with a striking dependence upon the structure of the alkylammonium cation. Two anion receptors were investigated, meso-octamethylcalix[4]pyrrole (C4P) and the bisthiourea tweezer 1,1'-(propane-1,3-diyl)bis(3-(4-sec-butylphenyl)thiourea (BTU). C4P has the unique ability in its cone anion-binding conformation to accept an appropriately sized electropositive species in the resulting cup formed by its four electron-rich pyrrole groups, while BTU is not expected to be predisposed for a specific host-guest interaction with the quaternary ammonium cations. It was therefore hypothesized that synergism between C4P and methyltri(C8,10)alkylammonium chloride (Aliquat 336) would be uniquely pronounced owing to insertion of the methyl group of the Aliquat cation into the C4P cup, and we present herein data supporting this expectation. While synergism is comparatively weak for both exchangers with the BTU receptor, synergism between C4P and Aliquat 336 is indeed so strong that anion exchange prefers chloride over more extractable nitrate and trifluoroacetate, effectively overcoming the ubiquitous Hofmeister bias. A thermochemical analysis of synergistic anion exchange has been provided for the first time, unraveling the observed selectivity behavior and resulting in the estimation of binding constants for C4P with the ion pairs of A336+ with Cl , Br , OAcF3 , NO3 , and I . The uniquely strong positive cooperativity between A336 and C4P underscores the advantage of a supramolecular approach in the design of synergistic anion exchange systems.

Borman, Christopher J [ORNL; Bonnesen, Peter V [ORNL; Moyer, Bruce A [ORNL

2012-01-01

233

Metabolic myopathies.  

PubMed

Disorders of glycogen, lipid or mitochondrial metabolism may cause two main clinical syndromes, namely (1) progressive weakness (eg, acid maltase, debrancher enzyme, and brancher enzyme deficiencies among the glycogenoses; long- and very-long-chain acyl-CoA dehydrogenase (LCAD, VLCAD), and trifunctional enzyme deficiencies among the fatty acid oxidation (FAO) defects; and mitochondrial enzyme deficiencies) or (2) acute, recurrent, reversible muscle dysfunction with exercise intolerance and acute muscle breakdown or myoglobinuria (with or without cramps) (eg, phosphorylase (PPL), phosphorylase b kinase (PBK), phosphofructokinase (PFK), phosphoglycerate kinase (PGK), phosphoglycerate mutase (PGAM), and lactate dehydrogenase (LDH) among the glycogenoses and carnitine palmitoyltransferase II (CPT II) deficiency among the disorders of FAO or (3) both (eg, PPL, PBK, PFK among the glycogenoses; LCAD, VLCAD, short-chain L-3-hydroxyacyl-CoA dehydrogenase (SCHAD), and trifunctional enzyme deficiencies among the FAO defects; and multiple mitochondrial DNA (mtDNA) deletions). Myoadenylate deaminase deficiency, a purine nucleotide cycle defect, is somewhat controversial and is characterized by exercise-related cramps leading rarely to myoglobinuria. PMID:8795843

Tein, I

1996-06-01

234

Effect of the synergistic anion on electron paramagnetic resonance spectra of iron-transferrin anion complexes is consistent with bidentate binding of the anion.  

PubMed Central

Continuous wave (cw) X-band EPR spectra at approximately 90 K were obtained for iron-transferrin-anion complexes with 18 anions. Each anion had a carboxylate group and at least one other polar moiety. As the second polar group was varied from hydroxyl to carbonyl to amine to carboxylate, the EPR spectra changed from a dominant signal at g' approximately 4.3 with a second smaller peak at g' approximately 9 to a broad signal with intensity between g' approximately 5 and 7. Computer simulation indicated that the changes in the EPR spectra were due to changes in the zero field splitting parameter ratio, E/D, from approximately 1/3 for carbonate anion to approximately 0.04 for malonate anion. Observation of iron-13C coupling in the electron spin echo envelope modulation (ESEEM) for iron transferrin [1-13C]pyruvate indicated that the carboxylate group was bound to the iron. It is proposed that all of the anions behave as bidentate ligands, with coordination to the iron through both the carboxylate and proximal groups, and the carboxyl group serves as a bridge between the iron and a positively charged group on the protein. PMID:1651123

Dubach, J; Gaffney, B J; More, K; Eaton, G R; Eaton, S S

1991-01-01

235

Coordinate transcriptional regulation of bile acid homeostasis and drug metabolism  

Microsoft Academic Search

Drugs and bile acids are taken up into hepatocytes by specialized transport proteins localized at the basolateral membrane, e.g., organic anion transporting polypeptides . Following intracellular metabolism by cytochrome P450 (CYP) enzymes, drug metabolites are excreted into bile or urine via ATP-dependent multidrug resistance proteins (MDR1 and MRPs). Bile acids are excreted mainly via the bile salt export pump (BSEP,

Jyrki J. Eloranta; Gerd A. Kullak-Ublick

2005-01-01

236

Direct band gap silicon allotropes.  

PubMed

Elemental silicon has a large impact on the economy of the modern world and is of fundamental importance in the technological field, particularly in solar cell industry. The great demand of society for new clean energy and the shortcomings of the current silicon solar cells are calling for new materials that can make full use of the solar power. In this paper, six metastable allotropes of silicon with direct or quasidirect band gaps of 0.39-1.25 eV are predicted by ab initio calculations at ambient pressure. Five of them possess band gaps within the optimal range for high converting efficiency from solar energy to electric power and also have better optical properties than the Si-I phase. These Si structures with different band gaps could be applied to multiple p-n junction photovoltaic modules. PMID:24971657

Wang, Qianqian; Xu, Bo; Sun, Jian; Liu, Hanyu; Zhao, Zhisheng; Yu, Dongli; Fan, Changzeng; He, Julong

2014-07-16

237

Brain responses to filled gaps  

PubMed Central

An unresolved issue in the study of sentence comprehension is whether the process of gap-filling is mediated by the construction of empty categories (traces), or whether the parser relates fillers directly to the associated verb’s argument structure. We conducted an event-related potentials (ERP) study that used the violation paradigm to examine the time course and spatial distribution of brain responses to ungrammatically filled gaps. The results indicate that the earliest brain response to the violation is an early left anterior negativity (eLAN). This ERP indexes an early phase of pure syntactic structure building, temporally preceding ERPs that reflect semantic integration and argument structure satisfaction. The finding is interpreted as evidence that gap-filling is mediated by structurally predicted empty categories, rather than directly by argument structure operations. PMID:16970985

Hestvik, Arild; Maxfield, Nathan; Schwartz, Richard G.; Shafer, Valerie

2007-01-01

238

Minority Gaps Smaller in Some Pentagon Schools. The Achievement Gap.  

ERIC Educational Resources Information Center

This third in a four-part series on why academic achievement gaps exist explains how U.S. Department of Defense schools for children of military families offer lessons on how to raise academic achievement among minority students. Minority students in these schools do better than their counterparts almost anywhere in the United States on…

Viadero, Debra

2000-01-01

239

Astroglial metabolic networks sustain hippocampal synaptic transmission.  

PubMed

Astrocytes provide metabolic substrates to neurons in an activity-dependent manner. However, the molecular mechanisms involved in this function, as well as its role in synaptic transmission, remain unclear. Here, we show that the gap-junction subunit proteins connexin 43 and 30 allow intercellular trafficking of glucose and its metabolites through astroglial networks. This trafficking is regulated by glutamatergic synaptic activity mediated by AMPA receptors. In the absence of extracellular glucose, the delivery of glucose or lactate to astrocytes sustains glutamatergic synaptic transmission and epileptiform activity only when they are connected by gap junctions. These results indicate that astroglial gap junctions provide an activity-dependent intercellular pathway for the delivery of energetic metabolites from blood vessels to distal neurons. PMID:19056987

Rouach, Nathalie; Koulakoff, Annette; Abudara, Veronica; Willecke, Klaus; Giaume, Christian

2008-12-01

240

Closing the Salary Gap Noreen Rossi  

E-print Network

Closing the Salary Gap Noreen Rossi Dawn Misra #12;Overview · Evidence of salary gap for women practices · Practices to avoid · Future directions #12;Evidence of salary gap for women · Academics://www.forbes.com/sites/katetaylor/2012/06/13/eve n-women-doctors-cant-escape-the-pay-gap/ #12;Starting salaries of new physicians reveal

Finley Jr., Russell L.

241

DYNAMIC MODELLING OF LIVING ANIONIC SOLUTION POLYMERIZATION OF STYRENE/BUTADIENE/DIVINYLBENZENE  

E-print Network

DYNAMIC MODELLING OF LIVING ANIONIC SOLUTION POLYMERIZATION OF STYRENE model for the living anionic solution polymerization of styrene/butadiene/divinylbenzene in a continuous kinetic reactor model for the living anionic solution polymerization of styrene

Schittkowski, Klaus

242

Gap junction hemichannels in astrocytes of the CNS  

PubMed Central

Connexins are protein subunits that oligomerize into hexamers called connexons, gap junction hemichannels or just hemichannels. Because some gap junction channels are permeable to negatively and/or positively charged molecules up to ~ 1kDa in size, it was thought that hemichannels should not open to the extracellular space. A growing amount of evidence indicates that opening of hemichannels does occur under both physiological and pathological conditions in astrocytes and other cell types. Electrophysiological studies indicate that hemichannels have a low open probability under physiological conditions but may have a much higher open probability under certain pathological conditions. Some of the physiological behaviours of astrocytes that have been attributed to gap junctions may, in fact, be mediated by hemichannels. Hemichannels constituted of Cx43, the main connexin expressed by astrocytes, are permeable to small physiologically significant molecules, such as ATP, NAD+ and glutamate, and may mediate paracrine as well as autocrine signalling. Hemichannels tend to be closed by negative membrane potentials, high concentrations of extracellular Ca2+ and intracellular H+ ions, gap junction blockers and protein phosphorylation. Hemichannels tend to be opened by positive membrane potentials and low extracellular Ca2+, and possibly by as yet unidentified cytoplasmic signalling molecules. Exacerbated hemichannel opening occurs in metabolically inhibited cells, including cortical astrocytes, which contributes to the loss of chemical gradients across the plasma membrane and speeds cell death. PMID:12940934

Saez, J. C.; Contreras, J. E.; Bukauskas, F. F.; Retamal, M. A.; Bennett, M. V. L.

2013-01-01

243

A network perspective on metabolic inconsistency  

PubMed Central

Background Integrating gene expression profiles and metabolic pathways under different experimental conditions is essential for understanding the coherence of these two layers of cellular organization. The network character of metabolic systems can be instrumental in developing concepts of agreement between expression data and pathways. A network-driven interpretation of gene expression data has the potential of suggesting novel classifiers for pathological cellular states and of contributing to a general theoretical understanding of gene regulation. Results Here, we analyze the coherence of gene expression patterns and a reconstruction of human metabolism, using consistency scores obtained from network and constraint-based analysis methods. We find a surprisingly strong correlation between the two measures, demonstrating that a substantial part of inconsistencies between metabolic processes and gene expression can be understood from a network perspective alone. Prompted by this finding, we investigate the topological context of the individual biochemical reactions responsible for the observed inconsistencies. On this basis, we are able to separate the differential contributions that bear physiological information about the system, from the unspecific contributions that unravel gaps in the metabolic reconstruction. We demonstrate the biological potential of our network-driven approach by analyzing transcriptome profiles of aldosterone producing adenomas that have been obtained from a cohort of Primary Aldosteronism patients. We unravel systematics in the data that could not have been resolved by conventional microarray data analysis. In particular, we discover two distinct metabolic states in the adenoma expression patterns. Conclusions The methodology presented here can help understand metabolic inconsistencies from a network perspective. It thus serves as a mediator between the topology of metabolic systems and their dynamical function. Finally, we demonstrate how physiologically relevant insights into the structure and dynamics of metabolic networks can be obtained using this novel approach. PMID:22583819

2012-01-01

244

Claudin-17 forms tight junction channels with distinct anion selectivity.  

PubMed

Barrier properties of tight junctions are determined by the claudin protein family. Many claudins seal this barrier, but others form paracellular channels. Among these, no claudins with general and clear-cut anion selectivity have yet been described, while for claudin-10a and claudin-4, only circumstantial or small anion selectivities have been shown. A claudin with unknown function and tissue distribution is claudin-17. We characterized claudin-17 by overexpression and knock-down in two renal cell lines. Overexpression in MDCK C7 cell layers caused a threefold increase in paracellular anion permeability and switched these cells from cation- to anion-selective. Knockdown in LLC-PK(1) cells indorsed the finding of claudin-17-based anion channels. Mutagenesis revealed that claudin-17 anion selectivity critically depends on a positive charge at position 65. Claudin-17 expression was found in two organs: marginal in brain but abundant in kidney, where expression was intense in proximal tubules and gradually decreased towards distal segments. As claudin-17 is predominantly expressed in proximal nephrons, which exhibit substantial, though molecularly not defined, paracellular chloride reabsorption, we suggest that claudin-17 has a unique physiological function in this process. In conclusion, claudin-17 forms channels within tight junctions with distinct anion preference. PMID:22402829

Krug, Susanne M; Günzel, Dorothee; Conrad, Marcel P; Rosenthal, Rita; Fromm, Anja; Amasheh, Salah; Schulzke, Jörg D; Fromm, Michael

2012-08-01

245

Closing the Gap: Identification of Human 3-Ketosteroid Reductase, the Last Unknown Enzyme  

E-print Network

Closing the Gap: Identification of Human 3- Ketosteroid Reductase, the Last Unknown Enzyme phosphate as cofactor. Expression of human and murine HSD17B7 in an Erg27p-deficient yeast strain cholesterol biosynthesis, thus completing the molecular cloning of all genes of this central metabolic pathway

Rogers, Simon

246

Aluminum impairs gap junctional intercellular communication between astroglial cells in vitro  

Microsoft Academic Search

The purpose of the present study was to investigate the effect of aluminum on gap junctional intercellular communication (GJIC) in cultured astrocytes. In the CNS the extracellular environment and metabolic status of neurons is dependent upon astrocytes, which are known to exhibit GJIC. This cell-to-cell communication provides a cytoplasmic continuity between adjacent cells, allowing exchange of diverse ions, second messengers,

Carsten Theiss; Karl Meller

2002-01-01

247

Neptunium Valence Chemistry in Anion Exchange Processing  

SciTech Connect

The current anion resin in use in HB-Line Phase II, Reillex{trademark} HPQ, was tested in the laboratory under expected plant conditions for Np processing and was found to load between 50 and 70 g Np per liter of resin. Losses varied from 0.2 to 15 percent depending on a number of parameters. Hydrazine in the feed at 0.02 to 0.05 M appeared to keep the Np from oxidizing and increasing the losses within four to seven days after the FS addition. Losses of up to three percent were observed five days after FS addition when hydrazine was not used in the feed, compared with 0.3 percent when the feed was loaded immediately after FS addition. Based on these test results the following processing conditions are recommended: (1) Feed conditions: 8 M HNO{sub 3}, 0.02 M hydrazine, 0.05 M excess FS, less than 5 days storage of solution after FS addition. (2) Wash conditions: 100 liters of 8 M HNO{sub 3}, no FS, no hydrazine. (3) Elution conditions: 0.17 M HNO{sub 3}, 0.05 M hydrazine, no FS. (4) Precipitation feed conditions: 0.03 M excess ascorbic acid, no additional hydrazine, no FS, precipitation within three days.

KYSER, EDWARD

2003-02-01

248

Ionic Block Copolymers for Anion Exchange Membranes  

NASA Astrophysics Data System (ADS)

Anion exchange membrane (AEM) fuel cells have regained interest because it allows the use of non-noble metal catalysts. Until now, most of the studies on AEM were based on random polyelectrolytes. In this work, Poly(vinylbenzyltrimethylammonium bromide)-b- (methylbutylene) ([PVBTMA][Br]-b-PMB) was studied by SAXS, TEM and dielectric spectroscopy to understand the fundamental structure-conductivity relationship of ion transport mechanisms within well-ordered block copolymers. The ionic conductivity and the formation of order structure were dependent on the casting solvent. Higher ion exchange capacity (IEC) of the membranes showed higher conductivity at as IEC values below 1.8mmol/g, as above this, the ionic conductivity decreases due to more water uptake leading to dilution of charge density. The humidity dependence of morphology exhibited the shifting of d-spacing to higher value and the alteration in higher characteristic peak of SAXS plot as the humidity increase from the dry to wet state. This phenomenon can be further explained by a newly developed polymer brush theory. Three ionic conduction pathways with different conduction mechanism within the membranes can be confirmed by broadband electric spectroscopy.

Tsai, Tsung-Han; Herbst, Dan; Giffin, Guinevere A.; di Noto, Vito; Witten, Tom; Coughlin, E. Bryan

2013-03-01

249

Oxidase Reactions of Tomato Anionic Peroxidase 1  

PubMed Central

Tomato (Lycopersicon esculentum Mill) anionic peroxidase was found to catalyze oxidase reactions with NADH, glutathione, dithiothreitol, oxaloacetate, and hydroquinone as substrates with a mean activity 30% that of horseradish peroxidase; this is in contrast to the negligible activity of the tomato enzyme as compared to the horseradish enzyme in catalyzing an indoleacetic acid-oxidase reaction with only Mn2+ and a phenol as cofactors. Substitution of Ce3+ for Mn2+ produced an 18-fold larger response with the tomato enzyme than with the horseradish enzyme, suggesting a significant difference in the autocatalytic indoleacetic acid-oxidase reactions with these two enzymes. In attempting to compare enzyme activities with 2,4-dichlorophenol as a cofactor, it was found that reaction rates increased exponentially with both increasing cofactor concentration and increasing enzyme concentration. While the former response may be analogous to allosteric control of enzyme activity, the latter response is contrary to the principle that reaction rate is proportional to enzyme concentration, and additionally makes any comparison of enzyme activity difficult. PMID:16664567

Brooks, James L.

1986-01-01

250

Distortions of ?-Coordinated Arenes with Anionic Character.  

PubMed

A qualitative analysis of the distortions that operate on the ? system of bridging arenes with anionic character is presented and substantiated by computational studies at the density functional B3LYP and CASSCF levels. The observed effects of bonding to two metal atoms and of the negative charge are an expansion of the arene ring due to the partial occupation of ?* orbitals, an elongation or compression distortion accompanied by a loss of the equivalence of carbon-carbon bonds due to a Jahn-Teller distortion of the arene dianions, and a ring puckering due to a second-order Jahn-Teller distortion that may appear independently of the existence of the first-order effect. The workings of the orbital mixing produced by these distortions have been revealed in a straightforward way by a pseudosymmetry analysis of the HOMOs of the distorted conformations. The systems studied include Li(I) and Y(III) adducts of benzene, as well as trimethylsilyl-substituted derivatives in the former case. An analysis of the structural data of a variety of purported di- and tetraanionic arene ligands coordinated to transition metals in several bridging modes has reproduced the main geometrical trends found in the computational study for the benzene and trimethylsilyl-substituted benzene dianions, allowing a classification of the variety of structural motifs found in the literature. PMID:25236369

Falceto, Andrés; Casanova, David; Alemany, Pere; Alvarez, Santiago

2014-11-01

251

Structures of medium sized tin cluster anions.  

PubMed

The structures of medium sized tin cluster anions Sn(n)(-) (n = 16-29) were determined by a combination of density functional theory, trapped ion electron diffraction and collision induced dissociation (CID). Mostly prolate structures were found with a structural motif based on only three repeatedly appearing subunit clusters, the Sn(7) pentagonal bipyramid, the Sn(9) tricapped trigonal prism and the Sn(10) bicapped tetragonal antiprism. Sn(16)(-) and Sn(17)(-) are composed of two face connected subunits. In Sn(18)(-)-Sn(20)(-) the subunits form cluster dimers. For Sn(21)(-)-Sn(23)(-) additional tin atoms are inserted between the building blocks. Sn(24)(-) and Sn(25)(-) are composed of a Sn(9) or Sn(10) connected to a Sn(15) subunit, which closely resembles the ground state of Sn(15)(-). Finally, in the larger clusters Sn(26)(-)-Sn(29)(-) additional bridging atoms again connect the building blocks. The CID experiments reveal fission as the main fragmentation channel for all investigated cluster sizes. This rather unexpected "pearl-chain" cluster growth mode is rationalized by the extraordinary stability of the building blocks. PMID:22071636

Wiesel, Anne; Drebov, Nedko; Rapps, Thomas; Ahlrichs, Reinhart; Schwarz, Ulrike; Kelting, Rebecca; Weis, Patrick; Kappes, Manfred M; Schooss, Detlef

2012-01-01

252

Multiple input electrode gap controller  

DOEpatents

A method and apparatus for controlling vacuum arc remelting (VAR) furnaces by estimation of electrode gap based on a plurality of secondary estimates derived from furnace outputs. The estimation is preferably performed by Kalman filter. Adaptive gain techniques may be employed, as well as detection of process anomalies such as glows.

Hysinger, Christopher L. (Austin, TX); Beaman, Joseph J. (Austin, TX); Melgaard, David K. (Albuquerque, NE); Williamson, Rodney L. (Albuquerque, NE)

1999-01-01

253

Large gap magnetic suspension system  

NASA Technical Reports Server (NTRS)

The design of a large gap magnetic suspension system is discussed. Some of the topics covered include: the system configuration, permanent magnet material, levitation magnet system, superconducting magnets, resistive magnets, superconducting levitation coils, resistive levitation coils, levitation magnet system, and the nitrogen cooled magnet system.

Abdelsalam, Moustafa K.; Eyssa, Y. M.

1991-01-01

254

The Racial Academic Achievement Gap  

ERIC Educational Resources Information Center

Closing the racial academic achievement gap is a problem that must be solved in order for future society to properly function. Minorities including African-American and Latino students' standardized test scores are much lower than white students. By the end of fourth grade, African American, Latino, and poor students of all races are two years…

Green, Toneka M.

2008-01-01

255

Multiple input electrode gap controller  

DOEpatents

A method and apparatus for controlling vacuum arc remelting (VAR) furnaces by estimation of electrode gap based on a plurality of secondary estimates derived from furnace outputs. The estimation is preferably performed by Kalman filter. Adaptive gain techniques may be employed, as well as detection of process anomalies such as glows. 17 figs.

Hysinger, C.L.; Beaman, J.J.; Melgaard, D.K.; Williamson, R.L.

1999-07-27

256

Mass gap from pressure inequalities  

E-print Network

We prove that a temperature independent mass distribution is identically zero below a mass threshold (mass gap) value, if the pressure satisfies certain inequalities. This supports the finding of a minimal mass in quark matter equation of state by numerical estimates and by substitution of analytic formulas. We present a few inequalities for the mass distribution based on the Markov inequality.

Tamas S. Biro; Andras Laszlo; Peter Van

2006-12-07

257

Assessing the impact of anion-? effects on phenylalanine ion structures using IRMPD spectroscopy.  

PubMed

The gas-phase structures of two halide-bound phenylalanine anions (PheX(-), X = Cl(-) or Br(-)) and five fluorinated derivatives have been identified using infrared multiple photon dissociation (IRMPD) spectroscopy. The addition of electron-withdrawing groups to the aromatic ring creates a ?-acidic system that additionally stabilizes the halide above the ring face. Detailed ion structures were determined by comparing the IRMPD spectra with harmonic and anharmonic infrared spectra computed using B3LYP/6-311++G(d,p) as well as with 298 K enthalpies and Gibbs energies determined by the MP2(full)/6-311++G(2d,2p)//B3LYP/6-311++G(d,p) and MP2(full)/aug-cc-pVTZ//B3LYP/6-311++G(d,p) methods. PheX(-) structures were found to be dependent on both the nature of the anion and the extent of ring fluorination. Canonical isomers were established to be the dominant structures in every case, but halide addition significantly narrowed the energy gap with zwitterionic potential energy surfaces. This enabled zwitterions to appear as minor contributors to the gas-phase populations of Phe35F2Cl(-) and PheF5Br(-). PMID:25294414

Burt, Michael; Wilson, Kathleen; Marta, Rick; Hasan, Moaraj; Scott Hopkins, W; McMahon, Terry

2014-10-21

258

Zintl-phase compounds with SnSb4 tetrahedral anions: Electronic structure and thermoelectric properties  

SciTech Connect

We report the investigation of Zintl-phase Na(K){sub 8}SnSb{sub 4} and related compounds that contain SnSb{sub 4} tetrahedral anions using first principles electronic structure, Boltzmann transport, and density functional phonon calculations. We find that these compounds are narrow-gap semiconductors and there is a combination of heavy and light bands at valence band edge, which may lead to a combination of high thermopower and reasonable conductivity. High values of the thermopower are found for p-type doping within the Boltzmann transport theory. Furthermore, these materials are expected to have low thermal conductivity due to their structures that consist of a network of weakly coupled SnSb{sub 4} clusters, which leads to low phonon frequencies. In particular, we find low-frequency optical phonons that should effectively scatter the heat-carrying acoustic phonons. These results are discussed in terms of the structure, which consists of anionic clusters. Based on the results, it is suggested that such compounds may represent a useful paradigm for finding new thermoelectric materials.

Zhang, Lijun; Du, Mao-Hua; Singh, David J.

2010-01-01

259

Voltage-dependent anion channel (VDAC) as mitochondrial governator--thinking outside the box.  

PubMed

Despite a detailed understanding of their metabolism, mitochondria often behave anomalously. In particular, global suppression of mitochondrial metabolism and metabolite exchange occurs in apoptosis, ischemia and anoxia, cytopathic hypoxia of sepsis and multiple organ failure, alcoholic liver disease, aerobic glycolysis in cancer cells (Warburg effect) and unstimulated pancreatic beta cells. Here, we propose that closure of voltage-dependent anion channels (VDAC) in the mitochondrial outer membrane accounts for global mitochondrial suppression. In anoxia, cytopathic hypoxia and ethanol treatment, reactive oxygen and nitrogen species, cytokines, kinase cascades and increased NADH act to inhibit VDAC conductance and promote selective oxidation of membrane-permeable respiratory substrates like short chain fatty acids and acetaldehyde. In cancer cells, highly expressed hexokinase binds to and inhibits VDAC to suppress mitochondrial function while stimulating glycolysis, but an escape mechanism intervenes when glucose-6-phosphate accumulates and dissociates hexokinase from VDAC. Similarly, glucokinase binds mitochondria of insulin-secreting beta cells, possibly blocking VDAC and suppressing mitochondrial function. We propose that glucose metabolism leads to glucose-6-phosphate-dependent unbinding of glucokinase, relief of VDAC inhibition, release of ATP from mitochondria and ATP-dependent insulin release. In support of the overall proposal, ethanol treatment of isolated rat hepatocytes inhibited mitochondrial respiration and accessibility to adenylate kinase in the intermembrane space, effects that were overcome by digitonin permeabilization of the outer membrane. Overall, these considerations suggest that VDAC is a dynamic regulator, or governator, of global mitochondrial function both in health and disease. PMID:16307870

Lemasters, John J; Holmuhamedov, Ekhson

2006-02-01

260

Theoretical study of the superoxide anion assisted firefly oxyluciferin formation  

NASA Astrophysics Data System (ADS)

This a theoretical Letter based on density functional theory, on the role of superoxide anion in firefly chemiluminescence in DMSO. We have found that this anion can attack luciferin radical molecules, thus forming a luciferin-like trianion. This latter molecule transfers an oxygen atom, which results in the formation of oxyluciferyl radical dianion and carbon dioxide molecules. Oxyluciferin is finally formed after an electron transfer from oxyluciferyl radical dianion to tert-BuOrad radical molecules. Thus, we have found evidence that firefly oxyluciferin can be formed in a energetically favorable superoxide anion-assisted reaction, without the need for the formation of firefly dioxetanone.

Pinto da Silva, Luís; Esteves da Silva, Joaquim C. G.

2013-12-01

261

The oxide anion accelerated retro-diels-alder reaction.  

PubMed

The widespread application of the retro-Diels-Alder reaction in synthesis has been hampered by the high temperatures usually required to effect cycloreversion. The discovery of the anionic oxy-Cope reaction was followed by predictions that the accelerating effect of the oxide anion should also be observed with other pericyclic reactions. Recently, such predictions have been confirmed for the retro-Diels-Alder reaction, which often proceeds rapidly at room temperature by oxide anion rate acceleration. Such mild retro-Diels-Alder reactions have now been employed in the synthesis of a range of molecular targets, including temperature-sensitive enediynes. PMID:24022946

Bunnage, M E; Nicolaou, K C

1997-02-01

262

Analysis of anions in drinking water by capillary ion electrophoresis.  

PubMed

Capillary ion electrophoresis (CIE) (Waters' trade name: Capillary Ion Analysis, CIA) is a capillary electrophoretic technique which is optimized for the rapid analysis of low-molecular-mass inorganic and organic ions. An electroosmotic flow modifier (OFM) was added to the chromate electrolyte and a negative power supply was used. Indirect UV detection at 254 nm was used throughout. Analysis of anions in a variety of drinking water samples was done. Anion analysis using this technique is rapid (less than 5.5 min), with little sample preparation required. Comparison of anion amounts found using CIA and conventional suppressed ion chromatography (IC) was done with good correlation between the two techniques. PMID:8814788

Oehrle, S A

1996-05-10

263

Specific anion effect in water-nonaqueous solvent mixtures: interplay of the interactions between anion, solvent, and polymer.  

PubMed

Ethanol (EtOH) and dimethylsulfoxide (DMSO) are polar protic and aprotic organic solvents, respectively. In the present work, we have investigated the anion-specific lower critical solution temperature (LCST) and upper critical solution temperature (UCST) behaviors of poly(N-isopropylacrylamide) (PNIPAM) in the H2O-EtOH and H2O-DMSO mixtures. The turbidity and differential scanning calorimetry studies show that the LCST for the anions follows the Hofmeister series at the molar fraction of EtOH (xE) or DMSO (xD) of 6%. At xE of 26%, the UCST for the anions also follows the Hofmeister series because the dominating interactions for the UCST behavior are similar to that for the LCST behavior in the H2O-EtOH mixtures. In the H2O-DMSO mixture at xD of 70%, an inverted V-shaped anion series is observed for the UCST behavior of PNIPAM. Our studies demonstrate that the specific anion effect on the phase transition behaviors of PNIPAM is influenced not only by the anionic polarization of hydrogen bonding between solvent molecules and PNIPAM but also by the anion adsorption on the PNIPAM chain surface. PMID:23980605

Liu, Lvdan; Wang, Tao; Liu, Chang; Lin, Ke; Liu, Guangming; Zhang, Guangzhao

2013-09-19

264

Gaps"  

ERIC Educational Resources Information Center

This study investigated the effect of daily quizzes on the performance of college students. Students in an introductory psychology course used their own wireless-enabled devices to take short Internet-based quizzes at the beginning of every class. The quiz items were drawn approximately equally from material covered in the readings and the…

What Works Clearinghouse, 2013

2013-01-01

265

Amphibian cathelicidin fills the evolutionary gap of cathelicidin in vertebrate.  

PubMed

Cathelicidins comprise a family of antimicrobial peptides (AMPs) sharing a highly conserved cathelin domain, and play a central role in the innate defense against infection in most of vertebrates. But so far it has not yet been found in amphibians although a large number of other groups of AMPs have been identified. In the current work, the first amphibian cathelicidin (cathelicidin-AL) has been characterized from the frog skin of Amolops loloensis. Cathelicidin-AL (RRSRRGRGGGRRGGSGGRGGRGGGGRSGAGSSIAGVGSRGGGGGRHYA) is a cationic peptide containing 48 amino acid residues (aa) with 12 basic aa and no acidic aa. The chemical synthesized peptide efficiently killed bacteria and some fungal species including clinically isolated drug-resistance microorganisms. The cDNA encoding cathelicidin-AL precursor was cloned from the skin cDNA library of A. loloensis. As other cathelicidins, the precursor of cathelicidin-AL also contains highly conserved anionic cathelin domain of cysteine proteinase inhibitor followed by the AMP fragment at C-terminus. Phylogenetic analysis revealed that as connecting link, the amphibian cathelicidin predates reptilia but postdates fish cathelicidin. The peptide purification combined with gene cloning results confirms the presence of cathelicidin in amphibians and filled the evolutionary gap of cathelicidin in vertebrate, considering amphibians' special niche as the animals bridging the evolutionary land-water gap. PMID:22009138

Hao, Xue; Yang, Hailong; Wei, Ling; Yang, Shilong; Zhu, Wenjuan; Ma, Dongying; Yu, Haining; Lai, Ren

2012-08-01

266

Air Gap Effects in LX-17  

SciTech Connect

Three experiments done over twenty years on gaps in LX-17 are reported. For the detonation front moving parallel to the gaps, jets of gas products were seen coming from the gaps at velocities greater than the detonation velocity. A case can be made that the jet velocity increased with gap thickness but the data is scattered. For the detonation front moving transverse to the gap, time delays were seen. The delays roughly increase with gap width, going from 0-70 ns at 'zero gap' to around 300 ns at 0.5-1 mm gap. Larger gaps of up to 6 mm width almost certainly stopped the detonation, but this was not proved. Real-time resolution of the parallel jets and determination of the actual re-detonation or failure in the transverse case needs to be done in future experiments.

Souers, P C; Ault, S; Avara, R; Bahl, K L; Boat, R; Cunningham, B; Gidding, D; Janzen, J; Kuklo, D; Lee, R; Lauderbach, L; Weingart, W C; Wu, B; Winer, K

2005-09-26

267

Equine digital veins are more sensitive to superoxide anions than digital arteries.  

PubMed

This work was designed to investigate (i) the effect of superoxide dismutase (SOD) inhibition on endothelial function and (ii) the free radical-induced endothelial dysfunction in equine digital veins (EDVs) and equine digital arteries (EDAs) isolated from healthy horses. EDV and EDA rings were suspended in a 5ml organ bath containing Krebs solution. After a 60min equilibration period, EDV and EDA rings were contracted with phenylephrine. Then, cumulative concentration-response curves (CCRCs) to acetylcholine were performed. In both EDVs and EDAs, acetylcholine (1nM to 10µM) produced concentration-dependent relaxation. We investigated the influence of SOD inhibition by diethyldithiocarbamate (DETC; 100µM), a CuZnSOD inhibitor, on EDAs and EDVs relaxant responses to acetylcholine. Acetylcholine -mediated relaxation was impaired by DETC only in EDVs. SOD activity assayed by a xanthine-xanthine oxidase method was higher in EDAs compared with EDVs (P<0.05). CCRCs to acetylcholine established in the presence of pyrogallol (30µM) or homocysteine (20µM), two superoxide anions generating systems showed that in both EDVs and EDAs, the acetylcholine-mediated relaxation was significantly impaired by pyrogallol and homocysteine. This impairment was more pronounced in EDVs than in EDAs. Moreover, the pyrogallol-induced impairment of acetylcholine-mediated relaxation was potentiated by DETC to a greater extent in EDVs. We concluded that due to the lower activity of SOD, EDVs are more sensitive to superoxide anions than EDAs. So, any alteration of superoxide anions metabolism is likely to have a more important impact on venous rather than arterial relaxation. PMID:25014758

Lapo, Rock Allister; Gogny, Marc; Chatagnon, Gérard; Lalanne, Valérie; Harfoush, Khaled; Assane, Moussa; Desfontis, Jean-Claude; Mallem, Mohamed Yassine

2014-10-01

268

Activation of the membrane glucolipid synthesis in Acholeplasma laidlawii by phosphatidylglycerol and other anionic lipids.  

PubMed

In membrane lipids of the prokaryote Acholeplasma laidlawii similar phase equilibria and a nearly constant spontaneous curvature are maintained by an extensive metabolic regulation of especially the major polar lipids monoglucosyldiacylglycerol (MGlcDAG) and diglucosyldiacylglycerol (DGlcDAG), forming nonlamellar and lamellar phases, respectively. A constant surface charge density is maintained by the anionic phospholipid fraction. These lipids are synthesized from phosphatidic acid in two competing pathways. The in vitro synthesis of MGlcDAG and DGlcDAG were totally lost upon delipidation of the membrane proteins by detergent solubilization or solvent extraction of lyophilized cells. Activities were restored by critical concentrations of anionic lipids, but not by bilayer or nonbilayer zwitterionic phospholipids or glucolipids. Phosphatidylglycerol (PG), and to a lesser extent certain other anionic lipids, could activate the synthesis of MGlcDAG in lipid bilayers, whereas the synthesis of DGlcDAG was similarly dependent upon PG only. Two endogenous phosphoglucolipids with no activating potency could partially replace the PG activator for the MGlcDAG synthesis but less so for DGlcDAG formation. A change of inert matrix from phosphatidylcholine to DGlcDAG lowered the apparent cooperativity, but enhanced the efficiency, of activation by PG for both glucolipid synthesizing enzymes, most strongly the synthesis of DGlcDAG. These results indicate that the enzymatic formation of MGlcDAG is regulated by the lipid surface charge density, whereas the consecutive step to DGlcDAG is more dependent upon the specific properties of PG. The modulating effect of the surrounding matrix on the activator efficiencies and cooperativity may constitute part of the bilayer-nonbilayer lipid regulation mechanism. PMID:8089114

Karlsson, O P; Dahlqvist, A; Wieslander, A

1994-09-23

269

Observational Properties of Protoplanetary Disk Gaps  

NASA Astrophysics Data System (ADS)

We study the effects of an annular gap induced by an embedded protoplanet on disk scattered light images and the infrared spectral energy distribution (SED). We find that the outer edge of a gap is brighter in the scattered light images than a similar location in a gap-free disk. The stellar radiation that would have been scattered by material within the gap is instead scattered by the disk wall at the outer edge of the gap, producing a bright ring surrounding the dark gap in the images. Given sufficient resolution, such gaps can be detected by the presence of this bright ring in scattered light images. A gap in a disk also changes the shape of the SED. Radiation that would have been absorbed by material in the gap is instead reprocessed by the outer gap wall. This leads to a decrease in the SED at wavelengths corresponding to the temperature at the radius of the missing gap material, and to a corresponding flux increase at longer wavelengths corresponding to the temperature of the outer wall. We note, however, that the presence of an annular gap does not change the bolometric IR flux; it simply redistributes the radiation previously produced by material within the gap to longer wavelengths. Although it will be difficult on the basis of the SED alone to distinguish between the presence of a gap and other physical effects, the level of changes can be sufficiently large to be measurable with current instruments (e.g., Spitzer).

Varnière, Peggy; Bjorkman, J. E.; Frank, Adam; Quillen, Alice C.; Carciofi, A. C.; Whitney, Barbara A.; Wood, Kenneth

2006-02-01

270

Genome-scale models of bacterial metabolism: reconstruction and applications  

PubMed Central

Genome-scale metabolic models bridge the gap between genome-derived biochemical information and metabolic phenotypes in a principled manner, providing a solid interpretative framework for experimental data related to metabolic states, and enabling simple in silico experiments with whole-cell metabolism. Models have been reconstructed for almost 20 bacterial species, so far mainly through expert curation efforts integrating information from the literature with genome annotation. A wide variety of computational methods exploiting metabolic models have been developed and applied to bacteria, yielding valuable insights into bacterial metabolism and evolution, and providing a sound basis for computer-assisted design in metabolic engineering. Recent advances in computational systems biology and high-throughput experimental technologies pave the way for the systematic reconstruction of metabolic models from genomes of new species, and a corresponding expansion of the scope of their applications. In this review, we provide an introduction to the key ideas of metabolic modeling, survey the methods, and resources that enable model reconstruction and refinement, and chart applications to the investigation of global properties of metabolic systems, the interpretation of experimental results, and the re-engineering of their biochemical capabilities. PMID:19067749

Durot, Maxime; Bourguignon, Pierre-Yves; Schachter, Vincent

2009-01-01

271

Anion size modulates salt taste in rats  

PubMed Central

The purpose of this study was to investigate the influence of anion size and the contribution of the epithelial sodium channel (ENaC) and the transient receptor potential vanilloid-1 (TRPV1) channel on sodium-taste responses in rat chorda tympani (CT) neurons. We recorded multiunit responses from the severed CT nerve and single-cell responses from intact, narrowly tuned and broadly tuned, salt-sensitive neurons in the geniculate ganglion simultaneously with stimulus-evoked summated potentials to signal when the stimulus contacted the lingual epithelium. Artificial saliva served as the rinse and solvent for all stimuli (0.3 M NH4Cl, 0.5 M sucrose, 0.03–0.5 M NaCl, 0.01 M citric acid, 0.02 M quinine hydrochloride, 0.1 M KCl, and 0.03–0.5 M Na-gluconate). We used the pharmacological antagonist benzamil to assess NaCl responses mediated by ENaC, and SB-366791 and cetylpyridinium chloride to assess responses mediated by TRPV1. CT nerve responses were greater to NaCl than Na-gluconate at each concentration; this was attributed mostly to broadly tuned, acid-generalist neurons that responded with higher frequency and shorter latency to NaCl than Na-gluconate. In contrast, narrowly tuned NaCl-specialist neurons responded more similarly to the two salts, but with subtle differences in temporal pattern. Benzamil reduced CT nerve and single-cell responses only of narrowly tuned neurons to NaCl. Surprisingly, SB-366791 and cetylpyridinium chloride were without effect on CT nerve or single-cell NaCl responses. Collectively, our data demonstrate the critical role that apical ENaCs in fungiform papillae play in processing information about sodium by peripheral gustatory neurons; the role of TRPV1 channels is an enigma. PMID:22205652

Breza, Joseph M.

2012-01-01

272

DETERMINATION OF TRACE ANIONS IN WATER BY MULTIDIMENSIONAL ION CHROMATOGRAPHY  

EPA Science Inventory

Selenate, selenite, and arsenate ions were separated from the major anions chloride, nitrate, and sulfate in drinking water, surface water, and groundwater sources by collecting a selected portion of the ion chromatogram, after suppression, on a concentrator column and reinjectin...

273

Preparation and evaluation of anion exchange open tubular column.  

PubMed

An anion open tubular column (OTC) by coating cationic latex particle onto the silica capillary with surface sulfonate functionalized has been prepared and evaluated. The performance of the OTC was observed to be superior to that of those prepared by the bare silica capillary without sulfonation in term of separation efficiency. To increase the surface area of the capillary, acid and base-based etching method for treating silica capillary wall was carried out and compared. An OTC with multiple layers was prepared by alternatively coating cationic and anionic latex particles aiming to further increase the column capacity. The anion OTC with size of 50 ?m i.d. × 1 m long demonstrated good separation of common inorganic anions with high efficiency (e.g. for NO(2)(-), its theory plate number is 11655 plate/m). PMID:23158296

Diao, Xuefang; Zhang, Feifang; Feng, Feng; Yang, Bingcheng; Liang, Xinmiao; Chu, Xiaogang

2012-11-15

274

Nitrate Anion Exchange in Pu-238 Aqueous Scrap Recovery Operations  

SciTech Connect

Strong base, nitrate anion exchange (IX) is crucial to the purification of {sup 238}Pu solution feedstocks with gross levels of impurities. This paper discusses the work involved in bench scale experiments to optimize the nitrate anion exchange process. In particular, results are presented of experiments conducted to (a) demonstrate that high levels of impurities can be separated from {sup 238}Pu solutions via nitrate anion exchange and, (b) work out chemical pretreatment methodology to adjust and maintain {sup 238}Pu in the IV oxidation state to optimize the Pu(IV)-hexanitrato anionic complex sorption to Reillex-HPQ resin. Additional experiments performed to determine the best chemical treatment methodology to enhance recovery of sorbed Pu from the resin, and VIS-NIR absorption studies to determine the steady state equilibrium of Pu(IV), Pu(III), and Pu(VI) in nitric acid are discussed.

Pansoy-Hjelvik, M.E.; Silver, G.L.; Reimus, M.A.H.; Ramsey, K.B.

1999-01-31

275

Permeant Anions Control Gating of Calcium-dependent Chloride Channels  

Microsoft Academic Search

The effects of external anions (SCN?, NO3?, I?, Br?, F?, glutamate, and aspartate) on gating of Ca2+-dependent Cl? channels from rat parotid acinar cells were studied using the whole-cell configuration of the patch-clamp technique. Shifts in the reversal potential of the current induced by replacement of external Cl? with foreign anions, gave the following selectivity sequence based on permeability ratios

P. Perez-Cornejo; J. A. De Santiago; J. Arreola

2004-01-01

276

Chiral tripode approach toward multiple anion sensing with lanthanide complexes  

Microsoft Academic Search

A chiral tripodal ligand was demonstrated to form a series of lanthanide complexes exhibiting multiple anion-sensing profiles, which incorporated a fluorescent quinoline and a stereo-controlled substituent in a tetradentate skeleton. This mainly gave 1:2 (lanthanide cation\\/ligand) complexes with lanthanide triflates but 1:1 complexes with lanthanide nitrates. Since addition of external guest anion dynamically changed the preferred stoichiometry, the chiral lanthanide

Miyuki Eiraku Masaki; Dharam Paul; Rie Nakamura; Yumiko Kataoka; Satoshi Shinoda; Hiroshi Tsukube

2009-01-01

277

GAS-GRAIN MODELS FOR INTERSTELLAR ANION CHEMISTRY  

SciTech Connect

Long-chain hydrocarbon anions C{sub n}H{sup -} (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n{sub H{sub 2}}{approx}>10{sup 5} cm{sup -3}). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C{sub 6}H{sup -} anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C{sub 6}O, C{sub 7}O, HC{sub 6}O, and HC{sub 7}O, the abundances of which depend on the assumed branching ratios for associative electron detachment.

Cordiner, M. A. [Also at Institute for Astrophysics and Computational Sciences, Catholic University of America, Washington, DC 20064 (United States); Charnley, S. B., E-mail: martin.cordiner@nasa.gov [Astrochemistry Laboratory and Goddard Center for Astrobiology, Mailstop 691, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20770 (United States)

2012-04-20

278

Target-aimed synthesis of anion-deficient perovskites.  

PubMed

The brownmillerite-type A 2B 2O 5 structure is considered as a parent one, giving rise to different derivatives: layered double perovskites, A-site and anion-vacancy-ordered perovskites, and the perovskite-like compounds with crystallographic shear planes. The structural relationships and synthesis pathways for these classes of materials are discussed with particular attention to the ordering at the A or B sublattices, anion vacancy ordering, and their mutual interaction. PMID:18821820

Antipov, Evgeny V; Abakumov, Artem M; Istomin, Sergey Ya

2008-10-01

279

Electronic gap sensor and method  

DOEpatents

Disclosed are an apparatus and method for regulating the gap between a casting nozzle and a casting wheel in which the gap between the casting nozzle and the casting wheel is monitored by means of at least one sensing element protruding from the face of the casting nozzle. The sensing element is preferably connected to a voltage source and the casting wheel grounded. When the sensing element contacts the casting wheel, an electric circuit is completed. The completion of the circuit can be registered by an indicator, and the presence or absence of a completed circuit indicates the relative position of the casting nozzle to the casting wheel. The relative positions of the casting nozzle and casting wheel can thereby be selectively adjusted to continually maintain a predetermined distance between their adjacent surfaces. 5 figures.

Williams, R.S.; King, E.L.; Campbell, S.L.

1991-08-06

280

Hard-gapped Holographic Superconductors  

E-print Network

In this work we discuss the zero temperature limit of a "p-wave" holographic superconductor. The bulk description consists of a non-Abelian SU(2) gauge fields minimally coupled to gravity. We numerically construct the zero temperature solution which is the gravity dual of the superconducting ground state of the "p-wave" holographic superconductors. The solution is a smooth soliton with zero horizon size and shows an emergent conformal symmetry in the IR. We found the expected superconducting behavior. Using the near horizon analysis we show that the system has a "hard gap" for the relevant gauge field fluctuations. At zero temperature the real part of the conductivity is zero for an excitation frequency less than the gap frequency. This is in contrast with what has been observed in similar scalar- gravity-gauge systems (holographic superconductors). We also discuss the low but finite temperature behavior of our solution.

Pallab Basu; Jianyang He; Anindya Mukherjee; Hsien-Hang Shieh

2009-11-26

281

Homolumo Gap and Matrix Model  

E-print Network

We discuss a dynamical matrix model by which probability distribution is associated with Gaussian ensembles from random matrix theory. We interpret the matrix M as a Hamiltonian representing interaction of a bosonic system with a single fermion. We show that a system of second-quantized fermions influences the ground state of the whole system by producing a gap between the highest occupied eigenvalue and the lowest unoccupied eigenvalue.

I. Andric; L. Jonke; D. Jurman; H. B. Nielsen

2007-12-21

282

Gender Pay Gap in Poland  

Microsoft Academic Search

In this paper we examine the gender pay gap in Poland over 1987–1996, i.e., shortly before and during the transition to market\\u000a economy. The principle source of data used throughout the paper is the Household Budget Survey conducted by the Polish Central\\u000a Statistical Office. The study documents three major results. First, the transition to market economy in Poland favored women

Micha? Grajek

2003-01-01

283

Uranyl nitrate-exposed rat alveolar macrophages cell death: Influence of superoxide anion and TNF ? mediators  

SciTech Connect

Uranium compounds are widely used in the nuclear fuel cycle, military and many other diverse industrial processes. Health risks associated with uranium exposure include nephrotoxicity, cancer, respiratory, and immune disorders. Macrophages present in body tissues are the main cell type involved in the internalization of uranium particles. To better understand the pathological effects associated with depleted uranium (DU) inhalation, we examined the metabolic activity, phagocytosis, genotoxicity and inflammation on DU-exposed rat alveolar macrophages (12.5–200 ?M). Stability and dissolution of DU could differ depending on the dissolvent and in turn alter its biological action. We dissolved DU in sodium bicarbonate (NaHCO{sub 3} 100 mM) and in what we consider a more physiological vehicle resembling human internal media: sodium chloride (NaCl 0.9%). We demonstrate that uranyl nitrate in NaCl solubilizes, enters the cell, and elicits its cytotoxic effect similarly to when it is diluted in NaHCO{sub 3}. We show that irrespective of the dissolvent employed, uranyl nitrate impairs cell metabolism, and at low doses induces both phagocytosis and generation of superoxide anion (O{sub 2}{sup ?}). At high doses it provokes the secretion of TNF? and through all the range of doses tested, apoptosis. We herein suggest that at DU low doses O{sub 2}{sup ?} may act as the principal mediator of DNA damage while at higher doses the signaling pathway mediated by O{sub 2}{sup ?} may be blocked, prevailing damage to DNA by the TNF? route. The study of macrophage functions after uranyl nitrate treatment could provide insights into the pathophysiology of uranium?related diseases. -- Highlights: ? Uranyl nitrate effect on cultured macrophages is linked to the doses and independent of its solubility. ? At low doses uranyl nitrate induces generation of superoxide anion. ? At high doses uranyl nitrate provokes secretion of TNF?. ? Uranyl nitrate induces apoptosis through all the range of doses tested.

Orona, N.S. [School of Science and Technology, National University of General Martín, Avda Gral Paz 5445 (1650) San Martín, Buenos Aires (Argentina)] [School of Science and Technology, National University of General Martín, Avda Gral Paz 5445 (1650) San Martín, Buenos Aires (Argentina); Tasat, D.R., E-mail: deborah.tasat@unsam.edu.ar [School of Science and Technology, National University of General Martín, Avda Gral Paz 5445 (1650) San Martín, Buenos Aires (Argentina); School of Dentistry, University of Buenos Aires, M. T. de Alvear 2142 (1122), Buenos Aires (Argentina)

2012-06-15

284

Anion-free bambus[6]uril and its supramolecular properties.  

PubMed

Methods for the preparation of anion-free bambus[6]uril (BU6) are presented. They are based on the oxidation of iodide anion, which is bound inside the macrocycle, utilizing dark oxidation by hydrogen peroxide or photooxidation in the presence of titanium dioxide. Anion-free BU6 was found to be insoluble in any of the investigated solvents; however, it dissolves in methanol/chloroform (1:1) or acetonitrile/water (1:1) mixtures in the presence of the tetrabutylammonium salt of a suitable anion. The association constants with halide ions, BF(4)(-), NO(3)(-), and CN(-), were measured by (1)H NMR spectroscopy. The highest association constant (8.9×10(5) M(-1)) was found for the 1:1 complex of BU6 with I(-) in acetonitrile/water mixture. A number of crystal structures of BU6 complexes with various anions were obtained. The influence of the anion size on the macrocycle diameter is discussed together with an unusual arrangement of the macrocycles into separate layers. PMID:21484899

Svec, Jan; Dusek, Michal; Fejfarova, Karla; Stacko, Peter; Klán, Petr; Kaifer, Angel E; Li, Wei; Hudeckova, Edita; Sindelar, Vladimir

2011-05-01

285

Anionic dicyanamide frameworks as possible components of multifunctional materials  

NASA Astrophysics Data System (ADS)

The dicyanamide anion, [ N(CN){2}] - (hereafter abbreviated dca), has been shown to be a versatile building block for the assembly of coordination polymers which are components of molecular superconductors, magnets and conducting/magnetic hybrid materials. Significantly different anion topologies have been observed. We report the first study of the use of alkylammonium cations as templates for [ M(dca){3}] - (M = Mn and Ni) anionic networks, including a novel three-dimensional anionic structure in the (Bu{3}NH){4}[ Mn{3}(dca){10}] salt. The molecular superconductors with the highest superconducting transition temperature, kappa -(ET){2}[ Cu(dca)X] [ X = Cl, Br; ET, commonly abbreviated as BEDT-TTF, is bis(ethylenedithio)tetrathiafulvalene] contain chains of diamagnetic Cu(I) ions linked by dca anions. The successful introduction of magnetically active transition metals into the charge-compensating dca layer will also be discussed. Specifically, we have synthesized and characterized the (ET){2}[ Mn(dca){3}] salt that contain a novel triangular, spin frustrated, anion lattice separated by conducting layers of ET radical cations. Key words. BEDT-TTF salt, tetraalkylammonium salts, dicyanamide, x-ray crystal structure.

Schlueter, J. A.; Geiser, U.; Manson, J. L.

2004-04-01

286

Prometheus and the Keeler gap  

NASA Astrophysics Data System (ADS)

Linblad resonances with Saturn’s satellites are located at many radii in the rings. While some cause density or bending waves, others hold gap edges from spreading, like the 2:1 resonance with Mimas located at the B-ring edge, the 7:6 resonance with Janus at the A-ring edge, and the 32:31 resonance with Prometheus at the inner edge of the Keeler gap. The latter is the case of study here.Theoretically, the inner edge of the Keeler gap should have 32 regular sinusoidal lobes, where either the maximum or the minimum radius is expected to be aligned with Prometheus and rotating with its mean motion. We show that such is not the case. Fit of occultation data shows the presence of the 32:31 resonance, however, the fit residuals is as high as the amplitude of the resonance amplitude (about 2 km). Analysis of the ISS data, shows irregularities overlapping the lobes (Tiscareno et al. 2005, DPS), that follow Keplerian motion. These irregularities may be due to clumps of particles with different eccentricities than the rest of the edge particles. This phenomenon may be caused by the resonance, as it has not been observed at other circular edges were no resonance is present at their location. The ISS data also shows that the lobe’s minimum/maximum is not perfectly aligned with the longitude of Prometheus, which may be due to libration about the centre of the resonance.

Tajeddine, Radwan; Nicholson, Phillip D.; Hedman, Matthew M.; French, Richard G.; Tiscareno, Matthew S.; Burns, Joseph A.

2014-11-01

287

Gap junctions and chagas disease.  

PubMed

Gap junction channels provide intercellular communication between cells. In the heart, these channels coordinate impulse propagation along the conduction system and through the contractile musculature, thereby providing synchronous and optimal cardiac output. As in other arrhythmogenic cardiac diseases, chagasic cardiomyopathy is associated with decreased expression of the gap junction protein connexin43 (Cx43) and its gene. Our studies of cardiac myocytes infected with Trypanosoma cruzi have revealed that synchronous contraction is greatly impaired and gap junction immunoreactivity is lost in infected cells. Such changes are not seen for molecules forming tight junctions, another component of the intercalated disc in cardiac myocytes. Transcriptomic studies of hearts from mouse models of Chagas disease and from acutely infected cardiac myocytes in vitro indicate profound remodelling of gene expression patterns involving heart rhythm determinant genes, suggesting underlying mechanisms of the functional pathology. One curious feature of the altered expression of Cx43 and its gene expression is that it is limited in both extent and location, suggesting that the more global deterioration in cardiac function may result in part from spread of damage signals from more seriously compromised cells to healthier ones. PMID:21884887

Adesse, Daniel; Goldenberg, Regina Coeli; Fortes, Fabio S; Jasmin; Iacobas, Dumitru A; Iacobas, Sanda; Campos de Carvalho, Antonio Carlos; de Narareth Meirelles, Maria; Huang, Huan; Soares, Milena B; Tanowitz, Herbert B; Garzoni, Luciana Ribeiro; Spray, David C

2011-01-01

288

Structural, electronic and magnetic properties of neutral and anionic Fe2(BO2)n (n=1-3) clusters  

NASA Astrophysics Data System (ADS)

Using Fe2 dimer as a prototype of transition-metal cluster calculations based on density functional theory have been carried out to study the effect of ligand and charge states on the geometry, bonding feature and magnetic coupling of neutral and anionic Fe2(BO2)n (n=1-3) clusters. For neutral Fe2(BO2)n clusters the spin multiplicity of the complex changes from 7 to 8 when n goes from 0 to 1, 2, and 3. With increasing number of ligands the Fe-Fe distance increases, the magnetic coupling between Fe-Fe changes from direct exchange to super exchange, and 3d-2p hybridization between Fe and O atoms becomes predominant. For anionic Fe2(BO2)n (n=1-3) clusters, the corresponding total magnetic moment is 0, 7 and 6?B, respectively. Compared with neutral clusters the HOMO-LUMO gaps of anionic species increase rapidly as more BO2 units are introduced. This study sheds light on the potential of superhalogens to tune electronic and magnetic properties of Fe clusters.

Zhao, Hong Min; Lin, Xia; Li, Yawei; Wang, Qian; Jena, Puru

2014-08-01

289

Cationic-anionic mediated charge compensation on La2Ti2O7 for visible light photocatalysis.  

PubMed

The cationic-anionic mediated charge compensation effect was studied in the layered perovskite La2Ti2O7 for the visible light photocatalysis. Our screened hybrid density functional study shows that the electronic structure of La2Ti2O7 can be tuned by the cationic (V, Nb, Ta)/anionic (N) mono- and co-doping. Such mono-doping creates impurity states in the band gap which helps the electron-hole recombination. But if the charge compensation is made by the cationic-anionic mediated co-doping then such impurity states can be removed and can be a promising strategy for visible light photocatalysis. The absolute band edge position of the doped La2Ti2O7 has been aligned with respect to the water oxidation/reduction potential. The calculated defect formation energy shows the stability of the co-doping system is improved due to the coulomb interactions and charge compensations effect. PMID:24013462

Liu, Peng; Nisar, Jawad; Pathak, Biswarup; Ahuja, Rajeev

2013-10-28

290

30 CFR 57.6603 - Air gap.  

Code of Federal Regulations, 2013 CFR

...NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Explosives Extraneous Electricity-Surface and Underground § 57.6603 Air gap. At least a 15-foot air gap shall be provided between the...

2013-07-01

291

Closing the Prescription Drug Coverage Gap  

MedlinePLUS

... How does the coverage gap discount work for brand-name drugs? Companies that make brand-name prescription ... entered the coverage gap, will all Medicare-covered brand-name prescription drugs be discounted? If a drug ...

292

Determination of anionic minerals in black and kombucha tea using ion chromatography  

Microsoft Academic Search

A simple, rapid and accurate method for the determination of anionic minerals in tea brew has been developed. The quantitative determination of anions – fluoride, chloride, bromide, iodide, nitrate, phosphate and sulphate was accomplished by anion exchange chromatography with conductometric detection. A Metrosep Anion Dual 2 analytical column connected in series with a Metrosep RP guard column was used for

Sangita D. Kumar; G. Narayan; S. Hassarajani

2008-01-01

293

Poly(vinylidene fluoride) based anion conductive ionomer as a catalyst binder for application in anion exchange membrane fuel cell  

NASA Astrophysics Data System (ADS)

An anion conductive polymeric ionomer incorporated into the electrodes of an anion exchange membrane fuel cell (AEMFC) can help to enhance anion transport in the catalyst layer of electrode, and thus improve the catalyst efficiency and performance of AEMFC. In this work, we report the synthesis and properties of a new type of anion conductive ionomer, which is synthesized by grafting of poly(vinylidene fluoride), or PVDF with poly(vinylbenzyltrimethylammonium chloride) via atom transfer radical polymerization. The ionomer obtained shows improved hydrophilicity relative to pristine PVDF, and exhibits an ion exchange capacity of 1.59 mmol g-1. When used in a direct hydrazine hydrate fuel cell (DHFC) as a catalyst binder, the synthesized ionomer imparts the DHFC a significantly improved power density, which is 5-10 fold as much as that of the cells without using such ionomer. The method developed here for anion exchange ionomer synthesis is facile, green and does not involve the use of carcinogenic chemicals such as chloromethylmethylether and trimethylamine, which are often used for conventional anion exchange membrane or ionomer synthesis.

Zhang, Fengxiang; Zhang, Huamin; Qu, Chao; Ren, Junxia

2011-03-01

294

Spark gap with low breakdown voltage jitter  

DOEpatents

Novel spark gap devices and electrodes are disclosed. The novel spark gap devices and electrodes are suitable for use in a variety of spark gap device applications. The shape of the electrodes gives rise to local field enhancements and reduces breakdown voltage jitter. Breakdown voltage jitter of approximately 5% has been measured in spark gaps according the invention. Novel electrode geometries and materials are disclosed.

Rohwein, Gerald J. (Albuquerque, NM); Roose, Lars D. (Albuquerque, NM)

1996-01-01

295

Gap Year: Time off, with a Plan  

ERIC Educational Resources Information Center

A gap year allows people to step off the usual educational or career path and reassess their future. According to people who have taken a gap year, the time away can be well worth it. This article can help a person decide whether to take a gap year and how to make the most of his time off. It describes what a gap year is, including its pros and…

Torpey, Elka Maria

2009-01-01

296

The GAP Online LGBT Mental Health Curriculum  

Microsoft Academic Search

The authors describe the development and publication of an online curriculum to teach psychiatry trainees about important topics in LGBT mental health (www.aglp.org\\/gap). The curriculum was written by members of the LGBT Committee of the Group for Advancement of Psychiatry (GAP, www.ourgap.org). This paper outlines the history and mission of GAP and the history of the GAP LGBT Committee. The

Mary E. Barber; Jack Drescher; Vernon Rosario

2012-01-01

297

Effects of Dietary Electrolyte Balance on Growth Performance, Nitrogen Metabolism and Some Blood Biochemical Parameters of Growing Rabbits  

PubMed Central

The effects of different dietary electrolyte balance (DEB) on growth performance, nitrogen (N) metabolism and some blood biochemical parameters were investigated in 2 to 3 months old growing rabbits. A total of 150 growing rabbits of 2 months age were randomly divided into five groups according to average body weight, with 30 rabbits in each group. The DEB levels of the five experimental diets were ?154, ?3.16, +201, +347, and +500 meq/kg of dry matter (DM), respectively. There was a 7-d adaptation period and a 23-d experimental period. The results showed that the DEB levels had a quadratic affect on the average daily feed intake (ADFI) (p<0.001). The greatest ADFI was achieved when the DEB level was +201 meq/kg DM. Fecal N (FN) content linearly decreased (0.047), while digestible N (DN), retained N (RN), efficiency of intake N converted into digestible N (DN/IN) and the efficiency of intake N converted into retained N (RN/IN) linearly increased with the DEB increase (0.020, 0.004, 0.021, and 0.049, respectively). Serum phosphorus (P) ion content linearly increased with the DEB increase (p = 0.036). The DEB had a quadratic relationship with serum anion gap (AG) (p = 0.002) and serum parathyroid hormone (PTH) content (p = 0.016). The DEB levels quadratically affected base excess (BE) in the plasma (p<0.001). In conclusion, the DEB unaffected growth performance but affected feed intake, N metabolism and some blood biochemical parameters of growing rabbits. PMID:25049763

Li, J. W.; Wang, X. P.; Wang, C. Y.; Zhu, Y. L.; Li, F. C.

2013-01-01

298

Low band gap polymers Organic Photovoltaics  

E-print Network

Low band gap polymers for Organic Photovoltaics Eva Bundgaard Ph.D. Dissertation Risø National Bundgaard Title: Low band gap polymers for Organic photovoltaics Department: The polymer department Report the area of organic photovoltaics are focusing on low band gap polymers, a type of polymer which absorbs

299

30 CFR 56.6603 - Air gap.  

Code of Federal Regulations, 2010 CFR

...1 2010-07-01 2010-07-01 false Air gap. 56.6603 Section 56.6603 Mineral Resources...Explosives Extraneous Electricity § 56.6603 Air gap. At least a 15-foot air gap shall be provided between the blasting circuit...

2010-07-01

300

30 CFR 57.6603 - Air gap.  

Code of Federal Regulations, 2010 CFR

...1 2010-07-01 2010-07-01 false Air gap. 57.6603 Section 57.6603 Mineral Resources...Electricity-Surface and Underground § 57.6603 Air gap. At least a 15-foot air gap shall be provided between the blasting circuit...

2010-07-01

301

Optimal robustness in the gap metric  

Microsoft Academic Search

The application of the gap metric to robust stabilization of feedback systems is considered. In particular, a solution to the problem of robustness optimization in the gap metric is presented. The problem of robust stabilization under simultaneous plant-controller perturbations is addressed, and the least amount of combined plant-controller uncertainty, measured by the gap metric, that can cause instability of a

T. T. Georgiou; M. C. Smith

1990-01-01

302

Low band gap polymers for organic photovoltaics  

Microsoft Academic Search

Low band gap polymer materials and their application in organic photovoltaics (OPV) are reviewed. We detail the synthetic approaches to low band gap polymer materials starting from the early methodologies employing quinoid homopolymer structures to the current state of the art that relies on alternating copolymers of donor and acceptor groups where strategies for band gap design are possible. Current

Eva Bundgaard; Frederik C. Krebs

2007-01-01

303

Bridging The Gap Between Culture And Academics  

Microsoft Academic Search

This paper examines the possibility of building a bridge between culture and academics in order to fill the gap between them, and the role of traditional culture in an academic setting. It is evident that there is a gap between Micronesian cultural heritage and modern educational concepts taught in the classroom. The gap is that there is no blending of

Patti Pedrus

2005-01-01

304

Inflammation and metabolic disorders  

Microsoft Academic Search

Metabolic and immune systems are among the most fundamental requirements for survival. Many metabolic and immune response pathways or nutrient- and pathogen-sensing systems have been evolutionarily conserved throughout species. As a result, immune response and metabolic regulation are highly integrated and the proper function of each is dependent on the other. This interface can be viewed as a central homeostatic

Gökhan S. Hotamisligil

2006-01-01

305

Discovery of Interstellar Anions in Cepheus and Auriga  

NASA Technical Reports Server (NTRS)

We report the detection of microwave emission lines from the hydrocarbon anion C6H(-) and its parent neutral C6H in the star-forming region LI251 A (in Cepheus), and the pre-stellar core LI512 (in Auriga). The carbon chain-bearing species C4H, HC3N, HC5N, HC7N, and C3S are also detected in large abundances. The observations of L1251A constitute the first detections of anions and long-chain polyynes and cyanopolyynes (with more than five carbon atoms) in the Cepheus Flare star-forming region, and the first detection of anions in the vicinity of a protostar outside of the Taurus molecular cloud complex, indicating a possible wider importance for anions in the chemistry of star formation. Rotational excitation temperatures have been derived from the HC3N hyperfine structure lines and are found to be 6.2 K for L1251A and 8.7 K for LI5l2. The anion-to-neutral ratios are 3.6% and 4.1%, respectively, which are within the range of values previously observed in the interstellar medium, and suggest a relative uniformity in the processes governing anion abundances in different dense interstellar clouds. This research contributes toward the growing body of evidence that carbon chain anions are relatively abundant in interstellar clouds throughout the Galaxy, but especially in the regions of relatively high density and high depletion surrounding pre-stellar cores and young, embedded protostars.

Cordiner, M. A.; Charnely, S. B.; Buckle, J. V.; Walsh, C.

2011-01-01

306

Valence anion of thymine in the DNA pi-stack.  

PubMed

Most of theoretical data on the stability of radical anions supported by nucleic acid bases have been obtained for anions of isolated nucleobases, their nucleosides, or nucleotides. This approach ignores the hallmark forces of DNA, namely, hydrogen bonding and pi-stacking interactions. Since these interactions might be crucial for the electron affinities of nucleobases bound in DNA, we report for the first time on the stability of the thymine valence anion in trimers of complementary bases possessing the regular B-DNA geometry but differing in base sequence. In order to estimate the energetics of electron attachment to a trimer, we developed a thermodynamic cycle employing all possible two-body interaction energies in the neutral and anionic duplex as well as the adiabatic electron affinity of isolated thymine. All calculations were carried out at the MP2 level of theory with the aug-cc-pVDZ basis set. The two-body interaction energies were corrected for the basis set superposition error, and in benchmark systems, they were extrapolated to the basis set limit and supplemented with correction for higher order correlation terms calculated at the CCSD(T) level. We have demonstrated that the sequence of nucleic bases has a profound effect on the stability of the thymine valence anion: the anionic 5'-CTC-3' (6.0 kcal/mol) sequence is the most stable configuration, and the 5'-GTG-3' (-8.0 kcal/mol) trimer anion is the most unstable species. On the basis of obtained results, one can propose DNA sequences that are different in their vulnerability to damage by low energy electron. PMID:18954049

Koby?ecka, Monika; Leszczynski, Jerzy; Rak, Janusz

2008-11-19

307

Anion Separation by Selective Crystallization of Metal-Organic-Frameworks  

SciTech Connect

A novel approach for the separation of anions from aqueous mixtures was demonstrated, which involves their selective crystallization with metal-organic frameworks (MOFs) containing urea functional groups. Self-assembly of Zn{sup 2+} with the N,N{prime}-bis(m-pyridyl)urea (BPU) linker results in the formation of one-dimensional MOFs including various anions for charge balance, which interact to different extents with the zinc nodes and the urea hydrogen-bonding groups, depending on their coordinating abilities. Thus, Cl{sup -}, Br{sup -}, I{sup -}, and SO{sub 4}{sup 2-}, in the presence of BPU and Zn{sup 2+}, form MOFs from water, in which the anions coordinate the zinc and are hydrogen-bonded to the urea groups, whereas NO{sub 3}{sup -} and ClO{sub 4}{sup -} anions either do not form MOFs or form water-soluble discrete coordination complexes under the same conditions. X-ray diffraction, FTIR, and elemental analysis of the coordination polymers precipitated from aqueous mixtures containing equivalent amounts of these anions indicated total exclusion of the oxoanions and selective crystallization of the halides in the form of solid solutions with the general composition ZnCl{sub x}Br{sub y}I{sub z} {center_dot} BPU (x + y + z = 2), with an anti-Hofmeister selectivity. The concomitant inclusion of the halides in the same structural frameworks facilitates the rationalization of the observed selectivity on the basis of the diminishing interactions with the zinc and urea acidic centers in the MOFs when going from Cl{sup -} to I{sup -}, which correlates with decreasing anionic charge density in the same order. The overall crystal packing efficiency of the coordination frameworks, which ultimately determines their solubility, also plays an important role in the anion crystallization selectivity under thermodynamic equilibration.

Custelcean, Radu [ORNL

2006-01-01

308

DISCOVERY OF INTERSTELLAR ANIONS IN CEPHEUS AND AURIGA  

SciTech Connect

We report the detection of microwave emission lines from the hydrocarbon anion C{sub 6}H{sup -} and its parent neutral C{sub 6}H in the star-forming region L1251A (in Cepheus), and the pre-stellar core L1512 (in Auriga). The carbon-chain-bearing species C{sub 4}H, HC{sub 3}N, HC{sub 5}N, HC{sub 7}N, and C{sub 3}S are also detected in large abundances. The observations of L1251A constitute the first detections of anions and long-chain polyynes and cyanopolyynes (with more than five carbon atoms) in the Cepheus Flare star-forming region, and the first detection of anions in the vicinity of a protostar outside of the Taurus molecular cloud complex, indicating a possible wider importance for anions in the chemistry of star formation. Rotational excitation temperatures have been derived from the HC{sub 3}N hyperfine structure lines and are found to be 6.2 K for L1251A and 8.7 K for L1512. The anion-to-neutral ratios are 3.6% and 4.1%, respectively, which are within the range of values previously observed in the interstellar medium, and suggest a relative uniformity in the processes governing anion abundances in different dense interstellar clouds. This research contributes toward the growing body of evidence that carbon chain anions are relatively abundant in interstellar clouds throughout the Galaxy, but especially in the regions of relatively high density and high depletion surrounding pre-stellar cores and young, embedded protostars.

Cordiner, M. A.; Charnley, S. B. [Astrochemistry Laboratory and The Goddard Center for Astrobiology, NASA Goddard Space Flight Center, Code 691, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Buckle, J. V. [Cavendish Astrophysics Group and Kavli Institute for Cosmology, Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HE (United Kingdom); Walsh, C.; Millar, T. J., E-mail: martin.cordiner@nasa.gov [Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast, BT7 1NN (United Kingdom)

2011-04-01

309

Plasma Acetone Metabolism in the Fasting Human  

PubMed Central

The metabolism of acetone was studied in lean and obese humans during starvation ketosis. Acetone concentrations in plasma, urine, and breath; and rates of endogenous production, elimination in breath and urine, and in vivo metabolism were determined. There was a direct relationship between plasma acetone turnover (20-77 ?mol/m2 per min) and concentration (0.19-1.68 mM). Breath and urinary excretion of acetone accounted for a 2-30% of the endogenous production rate, and in vivo metabolism accounted for the remainder. Plasma acetone oxidation accounted for ?60% of the production rate in 3-d fasted subjects and about 25% of the production rate in 21-d fasted subjects. About 1-2% of the total CO2 production was derived from plasma acetone oxidation and was not related to the plasma concentration or production rate. Radioactivity from [14C]acetone was not detected in plasma free fatty acids, acetoacetate, ?-hydroxybutyrate, or other anionic compounds, but was present in plasma glucose, lipids, and proteins. If glucose synthesis from acetone is possible in humans, this process could account for 11% of the glucose production rate and 59% of the acetone production rate in 21-d fasted subjects. During maximum acetonemia, acetone production from acetoacetate could account for 37% of the anticipated acetoacetate production, which implies that a significant fraction of the latter compound does not undergo immediate terminal oxidation. PMID:438326

Reichard, G. A.; Haff, A. C.; Skutches, C. L.; Paul, P.; Holroyde, C. P.; Owen, O. E.

1979-01-01

310

In vitro, rapid assembly of gap junctions is induced by cytoskeleton disruptors  

PubMed Central

We report here rapid assembly of gap junctions in prostate epithelial cells in vitro. Assembly of gap junctions can be induced by incubation at 0 degrees C followed by incubation at 37 degrees C. Colchicine (10(- 5) M, 10(-3) M) and cytochalasin B (25 micrograms/ml), 100 micrograms/ml) at room temperature or at 37 degrees C also induce assembly of gap junctions. Assembly of the junctions proceeds even in the presence of a metabolic inhibitor (dinitrophenol) or of an inhibitor of protein synthesis (cycloheximide). We conclude that assembly of gap junctions can proceed from a pool of pre-existing precursors. The experimental conditions that result in gap-junction assembly involve perturbation of the cytoskeleton. Therefore, we propose that the assembly of gap junctions requires convergent migration of precursor molecules whose positional control in the membrane is released by perturbation of the cytoskeleton. Aggregates of particles and rugosities, whose distribution size and shape is similar to that of gap junctions, may represent intermediate assembly stages. This would indicate that the final stages in the assembly take place only after convergence of the precursor molecules to the junctional site and involve profound conformational changes required for establishment of fully assembled connexons. PMID:6682422

1983-01-01

311

Gap deformation and classical wave localization in disordered two-dimensional photonic-band-gap materials  

E-print Network

Gap deformation and classical wave localization in disordered two-dimensional photonic-band-gap two ab initio numerical methods, we study the effects that disorder has on the spectral gaps and on wave localization in two-dimensional photonic-band-gap materials. We find that there are basically two

312

More Than One Gap: Dropout Rate Gaps Between and Among Black, Hispanic, and White Students  

Microsoft Academic Search

The achievement gap, traditionally measured by test scores, also can be documented by dropout behavior. Examining dropout behavior among Black, White, and Hispanic students, with a particular focus on gaps within groups and not just between Whites and minorities, shows a clearer picture of the achievement gap. The results of our study show multiple achievement gaps both between and within

Dick M. Carpenter; Al Ramirez

2007-01-01

313

Data Maintenance and Gap Analysis Project for  

E-print Network

The term “gap analysis ” is widely used today in conservation circles to denote a process by which priority areas for protection or conservation action are identified, usually using Geographic Information Systems (GIS) technology. The term “gap ” is used with the aim to identify conservation “gaps”, that is, elements or sites of concern that are currently not “protected”. Gap analysis is a step-wise process that can be undertaken at a variety of scales for a variety of ecological themes. An example of gap analysis methodology, used by the Ontario Ministry of Natural Resources (MNR) for the Lands for Life

Southern Ontario

314

Epigenetics and cancer metabolism.  

PubMed

Cancer cells adapt their metabolism to support proliferation and survival. A hallmark of cancer, this alteration is characterized by dysfunctional metabolic enzymes, changes in nutrient availability, tumor microenvironment and oncogenic mutations. Metabolic rewiring in cancer is tightly connected to changes at the epigenetic level. Enzymes that mediate epigenetic status of cells catalyze posttranslational modifications of DNA and histones and influence metabolic gene expression. These enzymes require metabolites that are used as cofactors and substrates to carry out reactions. This interaction of epigenetics and metabolism constitutes a new avenue of cancer biology and could lead to new insights for the development of anti-cancer therapeutics. PMID:24125862

Johnson, Christelle; Warmoes, Marc O; Shen, Xiling; Locasale, Jason W

2015-01-28

315

The Meter of Metabolism  

PubMed Central

The circadian system orchestrates the temporal organization of many aspects of physiology, including metabolism, in synchrony with the 24 hr rotation of the Earth. Like the metabolic system, the circadian system is a complex feedback network that involves interactions between the central nervous system and peripheral tissues. Emerging evidence suggests that circadian regulation is intimately linked to metabolic homeostasis, and that dysregulation of circadian rhythms can contribute to disease. Conversely, metabolic signals also feed back into the circadian system, modulating circadian gene expression and behavior. Here, we review the relationship between the circadian and metabolic systems, and the implications for cardiovascular disease, obesity and diabetes. PMID:18775307

Green, Carla B.; Takahashi, Joseph S.; Bass, Joseph

2013-01-01

316

In search of ionic liquids incorporating azolate anions.  

PubMed

Twenty-eight novel salts with tetramethyl-, tetraethyl-, and tetrabutylammonium and 1-butyl-3-methylimidazolium cations paired with 3,5-dinitro-1,2,4-triazolate, 4-nitro-1,2,3-triazolate, 2,4-dinitroimidazolate, 4,5-dinitroimidazolate, 4,5-dicyanoimidazolate, 4-nitroimidazolate, and tetrazolate anions have been prepared and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and single-crystal X-ray crystallography. The effects of cation and anion type and structure on the physicochemical properties of the resulting salts, including several ionic liquids, have been examined and discussed. Ionic liquids (defined as having m.p.<100 degrees C) were obtained with all combinations of the 1-butyl-3-methylimidazolium cation ([C(4)mim](+)) and the heterocyclic azolate anions studied, and with several combinations of tetraethyl or tetrabutylammonium cations and the azolate anions. The [C(4)mim](+) azolates were liquid at room temperature exhibiting large liquid ranges and forming glasses on cooling with glass-transition temperatures in the range of -53 to -82 degrees C (except for the 3,5-dinitro-1,2,4-triazolate salt with m.p. 33 degrees C). Six crystal structures of the corresponding tetraalkylammonium salts were determined and the effects of changes to the cations and anions on the packing of the structure have been investigated. PMID:16586524

Katritzky, Alan R; Singh, Shailendra; Kirichenko, Kostyantyn; Smiglak, Marcin; Holbrey, John D; Reichert, W Matthew; Spear, Scott K; Rogers, Robin D

2006-06-01

317

Oxidation of silicon surface with atomic oxygen radical anions  

NASA Astrophysics Data System (ADS)

The surface oxidation of silicon (Si) wafers by atomic oxygen radical anions (O- anions) and the preparation of metal-oxide-semiconductor (MOS) capacitors on the O- -oxidized Si substrates have been examined for the first time. The O- anions are generated from a recently developed O- storage-emission material of [Ca24Al28O64]4+.4O-(C12A7-O- for short). After it has been irradiated by an O- anion beam (0.5 ?A/cm2) at 300°C for 1-10 hours, the Si wafer achieves an oxide layer with a thickness ranging from 8 to 32 nm. X-ray photoelectron spectroscopy (XPS) results reveal that the oxide layer is of a mixture of SiO2, Si2O3, and Si2O distributed in different oxidation depths. The features of the MOS capacitor of < Al electrode/SiOx/SI > are investigated by measuring capacitance-voltage (C — V) and current-voltage (I — V) curves. The oxide charge density is about 6.0 × 1011 cm-2 derived from the C — V curves. The leakage current density is in the order of 10-6A/cm2 below 4MV/cm, obtained from the I — V curves. The O- anions formed by present method would have potential applications to the oxidation and the surface-modification of materials together with the preparation of semiconductor devices.

Wang, Lian; Song, Chong-Fu; Sun, Jian-Qiu; Hou, Ying; Li, Xiao-Guang; Li, Quan-Xin

2008-06-01

318

Nanoparticle conversion chemistry: Kirkendall effect, galvanic exchange, and anion exchange  

NASA Astrophysics Data System (ADS)

Conversion chemistry is a rapidly maturing field, where chemical conversion of template nanoparticles (NPs) into new compositions is often accompanied by morphological changes, such as void formation. The principles and examples of three major classes of conversion chemical reactions are reviewed: the Kirkendall effect for metal NPs, galvanic exchange, and anion exchange, each of which can result in void formation in NPs. These reactions can be used to obtain complex structures that may not be attainable by other methods. During each kind of conversion chemical reaction, NPs undergo distinct chemical and morphological changes, and insights into the mechanisms of these reactions will allow for improved fine control and prediction of the structures of intermediates and products. Conversion of metal NPs into oxides, phosphides, sulphides, and selenides often occurs through the Kirkendall effect, where outward diffusion of metal atoms from the core is faster than inward diffusion of reactive species, resulting in void formation. In galvanic exchange reactions, metal NPs react with noble metal salts, where a redox reaction favours reduction and deposition of the noble metal (alloying) and oxidation and dissolution of the template metal (dealloying). In anion exchange reactions, addition of certain kinds of anions to solutions containing metal compound NPs drives anion exchange, which often results in significant morphological changes due to the large size of anions compared to cations. Conversion chemistry thus allows for the formation of NPs with complex compositions and structures, for which numerous applications are anticipated arising from their novel catalytic, electronic, optical, magnetic, and electrochemical properties.

Anderson, Bryan D.; Tracy, Joseph B.

2014-10-01

319

Reactivity of Anions in Interstellar Media: Detectability and Applications  

NASA Astrophysics Data System (ADS)

We propose a general rule to distinguish between detectable and undetectable astronomical anions. We believe that only few anions live long enough in the interstellar medium and thus can be detected. Our method is based on quantum mechanical calculations capable of describing accurately the evolution of electronic states during chemical processes. The still not fully understood reactivity at low temperatures is discussed considering non-adiabatic effects. The role of excited states has usually been neglected in previous works which basically focused on the ground electronic state for interpretations of experimental observations. Here, we deal with unsaturated carbon chains (e.g., C n H-), which show a high density of electronic states close to their corresponding ground electronic states, complex molecular dynamics, and non-adiabatic phenomena. Our general rule shows that it is not sufficient that anions exist in the gas phase (in the laboratory) to be present in media such as astrophysical media, since formation and decomposition reactions of these anions may allow the population of anionic electronic states to autodetach, forming neutrals. For C n H, reactivity depends strongly on n, where long and short chains behave differently. Formation of linear chains is relevant.

Senent, M. L.; Hochlaf, M.

2013-05-01

320

Reversible Intercalation of Fluoride-Anion Receptor Complexes in Graphite  

NASA Technical Reports Server (NTRS)

We have demonstrated a route to reversibly intercalate fluoride-anion receptor complexes in graphite via a nonaqueous electrochemical process. This approach may find application for a rechargeable lithium-fluoride dual-ion intercalating battery with high specific energy. The cell chemistry presented here uses graphite cathodes with LiF dissolved in a nonaqueous solvent through the aid of anion receptors. Cells have been demonstrated with reversible cathode specific capacity of approximately 80 mAh/g at discharge plateaus of upward of 4.8 V, with graphite staging of the intercalant observed via in situ synchrotron X-ray diffraction during charging. Electrochemical impedance spectroscopy and B-11 nuclear magnetic resonance studies suggest that cointercalation of the anion receptor with the fluoride occurs during charging, which likely limits the cathode specific capacity. The anion receptor type dictates the extent of graphite fluorination, and must be further optimized to realize high theoretical fluorination levels. To find these optimal anion receptors, we have designed an ab initio calculations-based scheme aimed at identifying receptors with favorable fluoride binding and release properties.

West, William C.; Whitacre, Jay F.; Leifer, Nicole; Greenbaum, Steve; Smart, Marshall; Bugga, Ratnakumar; Blanco, Mario; Narayanan, S. R.

2007-01-01

321

REACTIVITY OF ANIONS IN INTERSTELLAR MEDIA: DETECTABILITY AND APPLICATIONS  

SciTech Connect

We propose a general rule to distinguish between detectable and undetectable astronomical anions. We believe that only few anions live long enough in the interstellar medium and thus can be detected. Our method is based on quantum mechanical calculations capable of describing accurately the evolution of electronic states during chemical processes. The still not fully understood reactivity at low temperatures is discussed considering non-adiabatic effects. The role of excited states has usually been neglected in previous works which basically focused on the ground electronic state for interpretations of experimental observations. Here, we deal with unsaturated carbon chains (e.g., C{sub n} H{sup -}), which show a high density of electronic states close to their corresponding ground electronic states, complex molecular dynamics, and non-adiabatic phenomena. Our general rule shows that it is not sufficient that anions exist in the gas phase (in the laboratory) to be present in media such as astrophysical media, since formation and decomposition reactions of these anions may allow the population of anionic electronic states to autodetach, forming neutrals. For C{sub n} H, reactivity depends strongly on n, where long and short chains behave differently. Formation of linear chains is relevant.

Senent, M. L. [Departamento de Quimica y Fisica Teoricas, Instituto de Estructura de la Materia, IEM-C.S.I.C., Serrano 121, Madrid E-28006 (Spain); Hochlaf, M., E-mail: senent@iem.cfmac.csic.es, E-mail: hochlaf@univ-mlv.fr [Laboratoire de Modelisation et Simulation Multi Echelle, Universite Paris-Est, MSME UMR 8208 CNRS, 5 boulevard Descartes, F-77454 Marne-la-Vallee (France)

2013-05-01

322

A versatile tripodal amide receptor for the encapsulation of anions or hydrated anions via formation of dimeric capsules.  

PubMed

A bowl-shaped tripodal receptor with an appropriately positioned amide functionality on the benzene platform and electron-withdrawing p-nitrophenyl terminals (L(1)) has been designed, synthesized, and studied for the anion binding properties. The single-crystal X-ray crystallographic analysis on crystals of L(1) with tetrabutylammonium salts of nitrate (1), acetate (2), fluoride (3), and chloride (4) obtained in moist dioxane medium showed encapsulation of two NO(3)(-), [(AcO)(2)(H(2)O)(4)](2-), [F(2)(H(2)O)(6)](2-), and [Cl(2)(H(2)O)(4)](2-) respectively as the anionic guests inside the staggered dimeric capsular assembly of L(1). The p-nitro substitution in the aryl terminals assisted the formation of dimeric capsular assembly of L(1) exclusively upon binding/encapsulating above different guests. Though L(1) demonstrates capsule formation upon anion or hydrated anion complexation for all of the anions studied here, its positional isomer with the o-nitro-substituted tripodal triamide receptor L(2) selectively formed the dimeric capsular assembly upon encapsulation of [F(2)(H(2)O)(6)](2-) and noncapsular aggregates in the cases of other anions such as Cl(-), NO(3)(-), and AcO(-). Interestingly, structural investigations upon anion exchange of the complexes revealed that both isomers have selectivity toward the formation of a [F(2)(H(2)O)(6)](2-) encapsulated dimeric capsule. In contrast, solution-state (1)H NMR titration studies of L(1) and L(2) in DMSO-d(6) with AcO(-) indicated 1:3 (host:guest) binding. PMID:20030371

Arunachalam, M; Ghosh, Pradyut

2010-02-01

323

Sustained metabolic scope.  

PubMed Central

Sustained metabolic rates (SusMR) are time-averaged metabolic rates that are measured in free-ranging animals maintaining constant body mass over periods long enough that metabolism is fueled by food intake rather than by transient depletion of energy reserves. Many authors have suggested that SusMR of various wild animal species are only a few times resting (basal or standard) metabolic rates (RMR). We test this conclusion by analyzing all 37 species (humans, 31 other endothermic vertebrates, and 5 ectothermic vertebrates) for which SusMR and RMR had both been measured. For all species, the ratio of SusMR to RMR, which we term sustained metabolic scope, is less than 7; most values fall between 1.5 and 5. Some of these values, such as those for Tour de France cyclists and breeding birds, are surely close to sustainable metabolic ceilings for the species studied. That is, metabolic rates higher than 7 times RMR apparently cannot be sustained indefinitely. These observations pose several questions: whether the proximate physiological causes of metabolic ceilings reside in the digestive tract's ability to process food or in each tissue's metabolic capacity; whether ceiling values are independent of the mode of energy expenditure; whether ceilings are set by single limiting physiological capacities or by coadjusted clusters of capacities (symmorphosis); what the ultimate evolutionary causes of metabolic ceilings are; and how metabolic ceilings may limit animals' reproductive effort, foraging behavior, and geographic distribution. PMID:2315323

Peterson, C C; Nagy, K A; Diamond, J

1990-01-01

324

Tunable transport gap in phosphorene.  

PubMed

In this article, we experimentally demonstrate that the transport gap of phosphorene can be tuned monotonically from ?0.3 to ?1.0 eV when the flake thickness is scaled down from bulk to a single layer. As a consequence, the ON current, the OFF current, and the current ON/OFF ratios of phosphorene field effect transistors (FETs) were found to be significantly impacted by the layer thickness. The transport gap was determined from the transfer characteristics of phosphorene FETs using a robust technique that has not been reported before. The detailed mathematical model is also provided. By scaling the thickness of the gate oxide, we were also able to demonstrate enhanced ambipolar conduction in monolayer and few layer phosphorene FETs. The asymmetry of the electron and the hole current was found to be dependent on the layer thickness that can be explained by dynamic changes of the metal Fermi level with the energy band of phosphorene depending on the layer number. We also extracted the Schottky barrier heights for both the electron and the hole injection as a function of the layer thickness. Finally, we discuss the dependence of field effect hole mobility of phosphorene on temperature and carrier concentration. PMID:25111042

Das, Saptarshi; Zhang, Wei; Demarteau, Marcel; Hoffmann, Axel; Dubey, Madan; Roelofs, Andreas

2014-10-01

325

Estimation of canopy gap size and gap shape using a hemispherical photograph  

Microsoft Academic Search

Gap size and gap shape are two important properties of forest gaps that can influence microsite conditions in a forest stand\\u000a and determine the recruitment and establishment of trees. There is no universally adopted method for measuring the gap size,\\u000a although several options are available. In addition, few methods have been proposed for measuring the gap shape. This paper\\u000a proposes

Lile Hu; Zhiwen Gong; Junsheng Li; Jiaojun Zhu

2009-01-01

326

Malate-induced feedback regulation of plasma membrane anion channels could provide a CO2 sensor to guard cells.  

PubMed

Plants have developed strategies to circumvent limitations in water supply through the adjustment of stomatal aperture in relation to the photosynthetic capacity (water-use efficiency). The CO2 sensor of guard cells, reporting on the metabolic status of the photosynthetic tissue, is, however, as yet unknown. We elucidated whether extracellular malate has the capability to serve as a signal metabolite in regulating the membrane properties of guard cells. Patch-clamp studies showed that slight variations in the external malate concentration induced major alterations in the voltage-dependent activity of the guard cell anion channel (GCAC1). Superfusion of guard cell protoplasts with malate solutions in the physiological range caused the voltage-gate to shift towards hyperpolarized potentials (Km(mal) = 0.4 mM elicits a 38 mV shift). The selectivity sequence of the anion channel NO3- (4.2) > or = I- (3.9) > Br- (1.9) > Cl- (1) > mal (0.1) indicates that malate is able to permeate GCAC1. The binding site for shifting the gate is, however, located on the extracellular face of the channel since cytoplasmic malate proved ineffective. Single-channel analysis indicates that extracellular malate affects the voltage-dependent mean open time rather than the unitary conductance of GCAC1. In contrast to malate the rise in the extracellular Cl- concentration increases the unit conductance of the anion efflux channel. We suggest that stomata sense changes in the intercellular CO2 concentration and thus the photosynthetic activity of the mesophyll via feedback regulation of anion efflux from guard cells through malate-sensitive GCAC1. PMID:7681395

Hedrich, R; Marten, I

1993-03-01

327

Autodetachment spectroscopy of a molecular anion using a diode laser  

SciTech Connect

Autodetachment spectroscopy, a technique for studying molecular anions, has been applied in the past using color-center lasers or visible dye lasers. In the present work, the technique has been extended to employ a relatively weak diode laser. Laser radiation drives an infrared vibrational-rotational transition in the molecular anion NH . The vibrationally excited anion autodetaches, and the resulting fast neutral is detected. The P{sub 1} (6.5,e{minus} > e) transition in the fundamental (1 < {minus}0) band of NH has been observed near 2806 cm{sup {minus}1} with a signal to noise ratio of 15:1 with a 30-s averaging time. The present experiment has fewer than 500 ions of a single quantum state in the apparatus at once, interacting with 5 microwatts of laser power. Future instrumental improvements can yield orders of magnitude improvement in sensitivity.

Marawar, R.W.; Cowles, D.C.; Keeler, R.E.; White, A.P.; Farley, J.W. [Univ. of Nevada, Las Vegas, NV (United States). Dept. of Physics

1994-12-31

328

Tunable Cytotoxicity of Rhodamine 6G via Anion Variations  

PubMed Central

Chemotherapeutic agents with low toxicity to normal tissues are a major goal in cancer research. In this regard, the therapeutic activities of cationic dyes, such as rhodamine 6G, toward cancer cells have been studied for decades with observed toxicities toward normal and cancer cells. Herein, we report rhodamine 6G-based organic salts with varying counter-anions that are stable under physiological conditions, display excellent fluorescence photostability, and more importantly have tunable chemotherapeutic properties. Our in-vitro studies indicate that the hydrophobic compounds of this series allow production of nanoparticles which are non-toxic to normal cells and toxic to cancer cells. Furthermore, the anions, in combination with cations such as sodium, were observed to be non-toxic to both normal and cancer cells. To the best of our knowledge, this is the first demonstration that both the cation and anion play an extremely important and cooperative role in the antitumor properties of these compounds. PMID:24059469

Magut, Paul K. S.; Das, Susmita; Fernand, Vivian E.; Losso, Jack; McDonough, Karen; Naylor, Brittni M.; Aggarwal, Sita; Warner, Isiah M.

2014-01-01

329

Cell wall bound anionic peroxidases from asparagus byproducts.  

PubMed

Asparagus byproducts are a good source of cationic soluble peroxidases (CAP) useful for the bioremediation of phenol-contaminated wastewaters. In this study, cell wall bound peroxidases (POD) from the same byproducts have been purified and characterized. The covalent forms of POD represent >90% of the total cell wall bound POD. Isoelectric focusing showed that whereas the covalent fraction is constituted primarily by anionic isoenzymes, the ionic fraction is a mixture of anionic, neutral, and cationic isoenzymes. Covalently bound peroxidases were purified by means of ion exchange chromatography and affinity chromatography. In vitro detoxification studies showed that although CAP are more effective for the removal of 4-CP and 2,4-DCP, anionic asparagus peroxidase (AAP) is a better option for the removal of hydroxytyrosol (HT), the main phenol present in olive mill wastewaters. PMID:25195693

Jaramillo-Carmona, Sara; López, Sergio; Vazquez-Castilla, Sara; Jimenez-Araujo, Ana; Rodriguez-Arcos, Rocio; Guillen-Bejarano, Rafael

2014-10-01

330

Adsorption behavior of anionic polyelectrolyte for chemical mechanical polishing (CMP).  

PubMed

In this work, we investigated the adsorption characteristics of anionic polyelectrolytes, which are used in shallow trench isolation chemical mechanical polishing with ceria abrasives. Specifically, the adsorption isotherms and chain conformation of anionic polyelectrolytes were studied in order to elucidate the difference in removal rates of silicon dioxide (SiO2) and silicon nitride (Si3N4) layers and the high selectivity characteristics of ceria slurry. Adsorption isotherms, FT-IR spectroscopy and contact angle measurements revealed that the anionic polyelectrolyte additives had much better adsorption affinities for the Si3N4 surface than for the SiO2 surface. Moreover, blanket wafer polishing results were successfully correlated with the adsorption isotherms of polyelectrolytes on the oxide particle suspensions. PMID:18078949

Kim, Sarah; So, Jae-Hyun; Lee, Dong-Jun; Yang, Seung-Man

2008-03-01

331

An anionic aluminabenzene bearing aromatic and ambiphilic contributions.  

PubMed

The synthesis and structure of an anionic aluminabenzene, which is the first example of an aluminum-containing heterobenzene, are reported. The molecular structure of this aluminabenzene exhibits a planar six-membered ring, and the absence of any bond alternation between its unsaturated bonds is consistent with the structural criteria of aromaticity. Theoretical calculations and the NMR spectroscopic analysis of this anionic aluminabenzene furthermore suggest that, in addition to the aromatic conjugation of six ?-electrons, an ambiphilic contribution from a Lewis acidic aluminum center and an anionic pentadienyl moiety are present. Due to this contribution, the aluminabenzene is able to react with Lewis bases such as 4-dimethylaminopyridine and electrophiles such as methyl iodide. PMID:24932841

Nakamura, Taichi; Suzuki, Katsunori; Yamashita, Makoto

2014-07-01

332

Gas-phase observation of multiply charged C60 anions.  

PubMed

Gas-phase observation of C60(1-), C60(3-), and C60(4-) anions generated at platinum and gold electrodes and detected by electrochemical/electrospray mass spectrometry is reported. The anions were electrochemically generated from solutions of C60 dissolved in toluene/acetonitrile as well as from reduction of C60 films on gold electrode surfaces. The gas-phase observation of C60(3-) and C60(4-), despite the fact that they have negative electron affinities, is a result of a Coulombic barrier to electron loss. The fact that C60(2-) was not detected in these experiments is ascribed to its limited solubility under the reaction conditions. These studies, which demonstrate the gas-phase kinetic stability of C60(3-) and C60(4-), illustrate the promise of electrochemical/electrospray mass spectrometry for the study of metastable anions. PMID:16833589

Cammarata, Vince; Guo, Tan; Illies, Andreas; Li, Lidong; Shevlin, Philip

2005-03-31

333

Solubility and transport of cationic and anionic patterned nanoparticles  

NASA Astrophysics Data System (ADS)

Diffusion and transport of nanoparticles (NPs) though nanochannels is important for desalination, drug delivery, and biomedicine. Their surface composition dictate their efficiency separating them by reverse osmosis, delivering into into cells, as well as their toxicity. We analyze bulk diffusion and transport through nanochannels of NPs with different hydrophobic-hydrophilic patterns achieved by coating a fraction of the NP sites with positive or negative charges via explicit solvent molecular dynamics simulations. The cationic NPs are more affected by the patterns, less water soluble, and have higher diffusion constants and fluxes than their anionic NPs counterparts. The NP-water interaction dependence on surface pattern and field strength explains these observations. For equivalent patterns, anionic NPs solubilize more than cationic NPs since the Coulomb interaction of free anionic NPs, which are much stronger than hydrophobic NP-water interactions, are about twice that of cationic NPs.

Su, Jiaye; Guo, Hongxia; Olvera de La Cruz, Monica

2012-02-01

334

Anionic solid lipid nanoparticles supported on protamine/DNA complexes  

NASA Astrophysics Data System (ADS)

The objective of this study was to design novel anionic ternary nanoparticles for gene delivery. These ternary nanoparticles were equipped with protamine/DNA binary complexes (150-200 nm) as the support, and the anionic formation was achieved by absorption of anionic solid lipid nanoparticles (<=20 nm) onto the surface of the binary complexes. The small solid lipid nanoparticles (SLNs) were prepared by a modified film dispersion-ultrasonication method, and adsorption of the anionic SLNs onto the binary complexes was typically carried out in water via electrostatic interaction. The formulated ternary nanoparticles were found to be relatively uniform in size (257.7 ± 10.6 nm) with a 'bumpy' surface, and the surface charge inversion from 19.28 ± 1.14 mV to -17.16 ± 1.92 mV could be considered as evidence of the formation of the ternary nanoparticles. The fluorescence intensity measurements from three batches of the ternary nanoparticles gave a mean adsorption efficiency of 96.75 ± 1.13%. Circular dichroism spectra analysis showed that the protamine/DNA complexes had been coated by small SLNs, and that the anionic ternary nanoparticles formed did not disturb the construction of the binary complexes. SYBR Green I analysis suggested that the ternary nanoparticles could protect the DNA from nuclease degradation, and cell viability assay results showed that they exhibit lower cytotoxicity to A549 cells compared with the binary complexes and lipofectamine. The transfection efficiency of the ternary nanoparticles was better than that of naked DNA and the binary complexes, and almost equal to that of lipofectamine/DNA complexes, as revealed by inversion fluorescence microscope observation. These results indicated that the anionic ternary nanoparticles could facilitate gene transfer in cultured cells, and might alleviate the drawbacks of the conventional cationic vector/DNA complexes for gene delivery in vivo.

Ye, Jiesheng; Wang, Aihua; Liu, Chunxi; Chen, Zhijin; Zhang, Na

2008-07-01

335

De Novo Structure-Based Design of Anion Receptors  

SciTech Connect

This tutorial review presents an account of how de novo structure-based design methods have been used to facilitate the discovery of novel anion receptors formed by combination of hydrogen bond donor groups. Topics include the development of criteria needed for the design, how the input structures for each design were obtained, and subsequent use of molecular modeling to more accurately rank the initial list of candidates produced by the builder. The effectiveness of the design approach is illustrated in several cases where host molecules identified on the computer were subsequently synthesized and shown to function as efficient anion hosts.

Hay, Benjamin [ORNL

2010-01-01

336

Polyatomic anion assistance in the assembly of [2]pseudorotaxanes.  

PubMed

We describe the use of polyatomic anions for the quantitative assembly of ion-paired complexes displaying pseudorotaxane topology. Our approach exploits the unique ion-pair recognition properties exhibited by noncovalent neutral receptors assembled through hydrogen-bonding interactions between a bis-calix[4]pyrrole macrocycle and linear bis-amidepyridyl-N-oxides. The complexation of bidentate polyatomic anions that are complementary in size and shape to the receptor's cavity, in which six NH hydrogen-bond donors converge, induces the exclusive formation of four particle-threaded assemblies. PMID:22428728

Valderrey, Virginia; Escudero-Adán, Eduardo C; Ballester, Pablo

2012-07-01

337

A theoretical study of ternary indole-cation-anion complexes.  

PubMed

The simultaneous interactions of an anion and a cation with a ? system were investigated by MP2 and M06-2X theoretical calculations. Indole was chosen as a model ? system for its relevance in biological environments. Two different orientations of the anion, interacting with the N-H and with the C-H groups of indole, were considered. The four cations (Na(+), NH4(+), C(NH2)3(+) and N(CH3)4(+)) and the four anions (Cl(-), NO3(-), HCOO(-) and BF4(-)) included in the study are of biological interest. The total interaction energy of the ternary complexes was calculated and separated into its two- and three-body components and all of them are further divided into their electrostatic, exchange, repulsion, polarization and dispersion contributions using the local molecular orbital-energy decomposition analysis (LMO-EDA) methodology. The binding energy of the indole-cation-anion complexes depends on both ions, with the cation having the strongest effect. The intense cation-anion attraction determines the geometric and energetic features in all ternary complexes. These structures, with both ions on the same side of the ? system, show an anti-cooperative interaction. However, the interaction is not only determined by electrostatics, but also the polarization contribution is important. Specific interactions like the one established between the anion and the N-H group of indole or the proton transfer between an acidic cation and a basic anion play a significant role in the energetics and the structure of particular complexes. The presence of the polar solvent as modelled with the polarizable continuum model (PCM) does not seem to have a significant effect on the geometry of the ternary complexes, but drastically weakens the interaction energy. Also, the strength of the interaction is reduced at a faster rate when the anion is pushed away, compared to the results obtained in the gas phase. The combination of PCM with the addition of one water molecule indicates that the PCM method properly reproduces the main energetic and geometrical changes, even at the quantitative level, but the explicit hydration allows refining the solvent effect and detecting cases that do not follow the general trend. PMID:25296040

Carrazana-García, Jorge A; Cabaleiro-Lago, Enrique M; Campo-Cacharrón, Alba; Rodríguez-Otero, Jesús

2014-10-29

338

Photoelectron spectroscopy of boron aluminum hydride cluster anions.  

PubMed

Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, BxAlyHz(-), were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms. PMID:24784280

Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H; Li, Xiang; Kiran, Boggavarapu; Kandalam, Anil K

2014-04-28

339

GAPS IN THE GD-1 STAR STREAM  

SciTech Connect

GD-1 is a long, thin, Milky Way star stream that has readily visible density variations along its length. We quantify the locations, sizes, and statistical significance of the density structure, i.e., gaps, using a set of scaled filters. The shapes of the filters are based on the gaps that develop in simulations of dark matter sub-halos crossing a star stream. The high Galactic latitude 8.4 kpc long segment of GD-1 that we examine has 8 {+-} 3 gaps of 99% significance or greater, with the error estimated on the basis of tests of the gap-filtering technique. The cumulative distribution of gaps more than three times the width of the stream is in good agreement with predictions for dark matter sub-halo encounters with cold star streams. The number of gaps narrower than three times the width of the GD-1 stream falls well below the cold stream prediction which is taken into account for the gap creation rate integrated over all sizes. Simple warm stream simulations scaled to GD-1 show that the falloff in gaps is expected for sub-halos below a mass of 10{sup 6} M{sub Sun }. The GD-1 gaps requires 100 sub-halos >10{sup 6} M{sub Sun} within 30 kpc, the apocenter of GD-1 orbit. These results are consistent with LCDM sub-halo predictions but further improvements in stream signal-to-noise and gap modeling will be welcome.

Carlberg, R. G. [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada); Grillmair, C. J., E-mail: carlberg@astro.utoronto.ca, E-mail: carl@ipac.caltech.edu [Spitzer Science Center, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

2013-05-10

340

Liquid Phase Miscibility Gap Materials  

NASA Technical Reports Server (NTRS)

The manner in which the microstructural features of liquid-phase miscibility gap alloys develop was determined. This will allow control of the microstructures and the resultant properties of these alloys. The long-duration low gravity afforded by the shuttle will allow experiments supporting this research to be conducted with minimal interference from buoyancy effects and gravitationally driven convection currents. Ground base studies were conducted on Al-In, Cu-Pb, and Te-Tl alloys to determine the effect of cooling rate, composition, and interfacial energies on the phase separation and solidification processes that influence the development of microstructure in these alloys. Isothermal and directional cooling experiments and simulations are conducted. The ground based activities are used as a technological base from which flight experiments formulated and to which these flight experiments are compared.

Gelles, S. H.; Markworth, A. J.

1985-01-01

341

Narrow gap electronegative capacitive discharges  

NASA Astrophysics Data System (ADS)

Narrow gap electronegative (EN) capacitive discharges are widely used in industry and have unique features not found in conventional discharges. In this paper, plasma parameters are determined over a range of decreasing gap length L from values for which an electropositive (EP) edge exists (2-region case) to smaller L-values for which the EN region connects directly to the sheath (1-region case). Parametric studies are performed at applied voltage Vrf=500 V for pressures of 10, 25, 50, and 100 mTorr, and additionally at 50 mTorr for 1000 and 2000 V. Numerical results are given for a parallel plate oxygen discharge using a planar 1D3v (1 spatial dimension, 3 velocity components) particle-in-cell (PIC) code. New interesting phenomena are found for the case in which an EP edge does not exist. This 1-region case has not previously been investigated in detail, either numerically or analytically. In particular, attachment in the sheaths is important, and the central electron density ne0 is depressed below the density nesh at the sheath edge. The sheath oscillations also extend into the EN core, creating an edge region lying within the sheath and not characterized by the standard diffusion in an EN plasma. An analytical model is developed using minimal inputs from the PIC results, and compared to the PIC results for a base case at Vrf=500 V and 50 mTorr, showing good agreement. Selected comparisons are made at the other voltages and pressures. A self-consistent model is also developed and compared to the PIC results, giving reasonable agreement.

Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J.

2013-10-01

342

Narrow gap electronegative capacitive discharges  

SciTech Connect

Narrow gap electronegative (EN) capacitive discharges are widely used in industry and have unique features not found in conventional discharges. In this paper, plasma parameters are determined over a range of decreasing gap length L from values for which an electropositive (EP) edge exists (2-region case) to smaller L-values for which the EN region connects directly to the sheath (1-region case). Parametric studies are performed at applied voltage V{sub rf}=500 V for pressures of 10, 25, 50, and 100 mTorr, and additionally at 50 mTorr for 1000 and 2000 V. Numerical results are given for a parallel plate oxygen discharge using a planar 1D3v (1 spatial dimension, 3 velocity components) particle-in-cell (PIC) code. New interesting phenomena are found for the case in which an EP edge does not exist. This 1-region case has not previously been investigated in detail, either numerically or analytically. In particular, attachment in the sheaths is important, and the central electron density n{sub e0} is depressed below the density n{sub esh} at the sheath edge. The sheath oscillations also extend into the EN core, creating an edge region lying within the sheath and not characterized by the standard diffusion in an EN plasma. An analytical model is developed using minimal inputs from the PIC results, and compared to the PIC results for a base case at V{sub rf}=500 V and 50 mTorr, showing good agreement. Selected comparisons are made at the other voltages and pressures. A self-consistent model is also developed and compared to the PIC results, giving reasonable agreement.

Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J. [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States)] [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States)

2013-10-15

343

Photoelectron Spectroscopy of Rare-Gas Solvated Nucleobase Anions  

NASA Astrophysics Data System (ADS)

Gas-phase polar molecular anions [uracil (U^-), thymine (T^-), 1-3 dimethyluracil (DMU^-)] solvated by rare gas atoms were studied by means of negative ion photoelectron spectroscopy. The photoelectron spectrum (PES) of U^-, T^-, and DMU^- each exhibit a distinctive dipole-bound (DB) spectral signature. The spectra of U^-, U^- (Ar)_1,2 and U^- (Kr)_1 also only displayed the DB anion feature. Upon the solvation of more rare gas atoms, the spectra of U^- (Ar)_3, U^- (Kr)_2, and U^- (Xe)1-3 not only retained the DB signature but also exhibited the valence anion features. Moreover, the DB and the valence features shifted together to higher electron binding energies (EBEs) with increasing numbers of rare gas solvent atoms. Therefore, the co-existing DB and the valence anions appeared to be strongly coupled with each other, i.e. they effectively form a single state that is a superposition of both DB and valence anion states. For both U^- and T^- series, the ``onset size" of the Xe, Kr, and Ar solvents for the co-existing of the two anionic states was 1, 2, and 3 respectively. In addition, a minimum of 2 methane (CH_4) molecules or 1 ethane (C_2H_6) molecule were required to induce the coupling between the two states in the T^- series. Thus, the nucleobase anion interaction with non-polar solvent atoms tracks as the sum of the solvent polarizabilities. However for the DMU- series, the DB and the valence anions of DMU^-(Xe)_1, DMU^-(Kr)_2, and DMU^-(Ar)_3 were completely absent in both the mass spectra and the PES. Beyond these ``holes", their PES displayed the similar behaviors to the U^- and T^- series. Extrapolated EA values for these missing species were at or very close to zero, which may explain why they were not seen. However, why this was the case is not clear. With better Franck-Condon overlap between the origins of the NB^- (Rg)_n valence anion and the neutral NB(Rg)n than between those of the NB^- (H2O)n valence anion and the neutral NB(H2O)n, extrapolation of the valence electron affinities, measured from the NB(Rg)_n^- valence anions, should lead to significantly improved estimations of the valence electron affinity values of canonical, molecular nucleobases. EA_v(U) = 36 ±3 meV, EA_v(T) = 32 ± 7 meV, EA_v(1,3-DMU) = -34 ± 8 meV, and EA_v(A) = -80 meV, are our best recommended extrapolated EA_v values from our experiments. J. Chen, A. M. Buonaugurio and K. H. Bowen, TBA

Buonaugurio, Angela M.; Chen, Jing; Bowen, Kit H.

2012-06-01

344

EFFECTS OF SELECTED ANTI-TUMOR-PROMOTING CHEMICALS ON METABOLIC COOPERATION BETWEEN CHINESE HAMSTER V79 CELLS  

EPA Science Inventory

Many tumor-promoting chemicals inhibit gap junctional communication between cells. we investigated the possibility that antipromoting chemicals may act inversely and enhance gap junctional communication. he V79/metabolic cooperation assay is an in vitro test that measures pp junc...

345

Metabolism, Longevity and Epigenetics  

PubMed Central

Metabolic homeostasis, as well as interventions that influence nutrients’ uptake, are well-established means to influence lifespan even in higher eukaryotes. Until recently, molecular mechanisms to explain such an effect remained scantily understood. Sirtuins represent a group of protein deacetylases that depend on the metabolic intermediate NAD+ as a co-factor for their function. For this reason they sense metabolic stress and in turn function at multiple levels to exert proper metabolic adaptation. Among other things, sirtuins could perform as histone deacetylases inducing epigenetic changes to modulate transcription and DNA repair. Recent studies indicate that beyond sirtuins, the activity of other chromatin modifiers, such as histone acetyl transferases (HATs), might also be tightly linked to the availability of their intermediate metabolite Acetyl-CoA. In this study, we will summarize current knowledge depicting emerging concepts indicating a close crosstalk between the epigenetic machineries able to sense metabolic stress, their adaptive metabolic responses and their potential role in longevity. PMID:23467663

Cosentino, Claudia; Mostoslavsky, Raul

2013-01-01

346

Metabolism, longevity and epigenetics.  

PubMed

Metabolic homeostasis and interventions that influence nutrient uptake are well-established means to influence lifespan even in higher eukaryotes. Until recently, the molecular mechanisms explaining such an effect remained scantily understood. Sirtuins are a group of protein deacetylases that depend on the metabolic intermediate NAD(+) as a cofactor for their function. For this reason they sense metabolic stress and in turn function at multiple levels to exert proper metabolic adaptation. Among other things, sirtuins can perform as histone deacetylases inducing epigenetic changes to modulate transcription and DNA repair. Recent studies have indicated that beyond sirtuins, the activity of other chromatin modifiers, such as histone acetyl transferases, might also be tightly linked to the availability of their intermediate metabolite acetyl-CoA. We summarize current knowledge of the emerging concepts indicating close crosstalk between the epigenetic machineries able to sense metabolic stress, their adaptive metabolic responses and their potential role in longevity. PMID:23467663

Cosentino, Claudia; Mostoslavsky, Raul

2013-05-01

347

Metabolic Syndrome and Migraine  

PubMed Central

Migraine and metabolic syndrome are highly prevalent and costly conditions. The two conditions coexist, but it is unclear what relationship may exist between the two processes. Metabolic syndrome involves a number of findings, including insulin resistance, systemic hypertension, obesity, a proinflammatory state, and a prothrombotic state. Only one study addresses migraine in metabolic syndrome, finding significant differences in the presentation of metabolic syndrome in migraineurs. However, controversy exists regarding the contribution of each individual risk factor to migraine pathogenesis and prevalence. It is unclear what treatment implications, if any, exist as a result of the concomitant diagnosis of migraine and metabolic syndrome. The cornerstone of migraine and metabolic syndrome treatments is prevention, relying heavily on diet modification, sleep hygiene, medication use, and exercise. PMID:23181051

Sachdev, Amit; Marmura, Michael J.

2012-01-01

348

Ba5Ga4Se10: a new selenidogallate containing the novel [Ga4Se10](10-) anionic cluster with Ga in a mixed-valence state.  

PubMed

The new compound Ba(5)Ga(4)Se(10) has been synthesized for the first time. It crystallizes in the tetragonal space group I4/mcm with a = 8.752(2) Å, c = 13.971(9) Å, and Z = 2. The structure contains discrete [Ga(4)Se(10)](10-) anions and charge-compensating Ba(2+) cations. The novel highly anionic [Ga(4)Se(10)](10-) cluster is composed of two Ga(Se)(4) tetrahedra and two Ga(Ga)(Se)(3) tetrahedra with Ga in the 2+/3+ valence states. It also exhibits an unusually long Ga-Se distance of 2.705(2) Å, which has only been observed under high pressure conditions before. A band gap of 2.20(2) eV was deduced from the UV/vis diffuse reflectance spectrum. PMID:21822514

Yin, Wenlong; Mei, Dajiang; Feng, Kai; Yao, Jiyong; Fu, Peizhen; Wu, Yicheng

2011-09-28

349

[Gap edge effect of Castanopsis kawakamii community].  

PubMed

This paper reported the characters of gap edge effect of Castanopsis kawakamii community in Sanming, Fujian Province. The species diversity, ecological dominance, and edge effect strength of 38 forest gaps with different development stages in different stands of Castanopsis kawakamii community were measured, and Shannon-Wiener index, Simpson index, and index of edge effect strength were calculated. The results showed that the index of the gap edge effect of Castanopsis kawakamii community was about 0.7-1.3 (according to the species diversity index) and 0.3-1.8 (according to the ecological dominance index). The gap edge effect had the trend of increasing the species diversity of forest communities. The index of gap effect was affected by the size and development stage of the gap and the related forest type. The study provided a theoretical basis for the maintenance of species diversity and the forest management in Castanopsis kawakamii community. PMID:14732992

Liu, Jinfu; Hong, Wei; Li, Junqing; Lin, Rongfu

2003-09-01

350

Fluorinated Calixpyrroles: Anion-Binding Extractants that Reduce the Hofmeister Bias  

SciTech Connect

b-Fluorinated calix[4]pyrrole 1 and calix[5]pyrrole 2, strong, neutral anion-binding agents, were found to transport small anions effectively while overcoming the classical solvation-based Hofmeister anion bias selectivity. These two receptors showed an ability to extract smaller anions (bromide and chloride for 1 and nitrate and fluoride for 2) as effectively as iodide anion into nitrobenzene (NB). The present results also represent a rare example of liquid-liquid extraction of inorganic salts effected using an anion receptor in the absence of a cation co-extractant.

Levitskaia, Tatiana G.; Marquez, Manuel; Sessler, Jonathan L.; Shriver, James A.; Vercouter, Thomas; Moyer, Bruce A.

2003-04-30

351

Metabolic alteration in tumorigenesis.  

PubMed

Altered metabolism in cancer was first discovered by Otto Warburg early last century. Although the Warburg Effect has been widely used in tumor detection, relatively little progress had been made in mechanistic understanding of cancer metabolism in the subsequent eight decades. Genetic studies have recently identified mutations in human cancer targeting multiple enzymes involved in intermediate metabolism. One emerging mechanism common to these mutant enzymes is the accumulation of a metabolite that alters the epigenetic control. PMID:24114443

Yang, Hui; Xiong, Yue; Guan, KunLiang

2013-12-01

352

Metabolism of arsenic and its toxicological relevance.  

PubMed

Arsenic is a worldwide environmental pollutant and a human carcinogen. It is well recognized that the toxicity of arsenicals largely depends on the oxidoreduction states (trivalent or pentavalent) and methylation levels (monomethyl, dimethyl, and trimethyl) that are present during the process of metabolism in mammals. However, presently, the specifics of the metabolic pathway of inorganic arsenicals have yet to be confirmed. In mammals, there are two possible mechanisms that have been proposed for the metabolic pathway of inorganic arsenicals, oxidative methylation, and glutathione conjugation. Oxidative methylation, which was originally proposed in fungi, is based on findings that arsenite (iAs(III)) is sequentially converted to monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)) in both humans and in laboratory animals such as mice and rats. However, recent in vitro observations have demonstrated that arsenic is only methylated in the presence of glutathione (GSH) or other thiol compounds, which strongly suggests that arsenic is methylated in trivalent forms. The glutathione conjugation mechanism is supported by findings that have shown that most intracellular arsenicals are trivalent and excreted from cells as GSH conjugates. Since non-conjugated trivalent arsenicals are highly reactive with thiol compounds and are easily converted to less toxic corresponding pentavalent arsenicals, the arsenic-glutathione conjugate stability may be the most important factor for determining the toxicity of arsenicals. In addition, "being a non-anionic form" also appears to be a determinant of the toxicity of oxo-arsenicals or thioarsenicals. The present review discusses both the metabolism of arsenic and the toxicity of arsenic metabolites. PMID:22811022

Watanabe, Takayuki; Hirano, Seishiro

2013-06-01

353

Gap junctions in health and disease  

Microsoft Academic Search

An international symposium was held on gap junctions in health and disease in Regensburg, Germany, gathering together a panel\\u000a of international scientists who discussed normal functions of gap junctions and their contribution to a variety of human diseases.\\u000a The emphasis was on strategies and models for a better understanding of gap junction-mediated cell-to-cell communication in\\u000a a variety of tissues, including

R. Dermietzel; F. Hofstädter

1998-01-01

354

Chiral gap effect in curved space  

E-print Network

We discuss a new type of QCD phenomenon induced in curved space. In the QCD vacuum a mass gap of Dirac fermions is attributed to the spontaneous breaking of chiral symmetry. If the curvature is positive large, the chiral condensate melts but a chiral invariant mass gap can still remain, which we name the chiral gap effect in curved space. This leads to decoupling of quark deconfinement which implies a view of black holes surrounded by a first-order QCD phase transition.

Antonino Flachi; Kenji Fukushima

2014-06-25

355

Mevalonate metabolism in cancer.  

PubMed

Cancer cells are characterized by sustained proliferative signaling, insensitivity to growth suppressors and resistance to apoptosis as well as by replicative immortality, the capacity to induce angiogenesis and to perform invasive growth. Additional hallmarks of cancer cells include the reprogramming of energy metabolism as well as the ability to evade immune surveillance. The current review focuses on the metabolic reprogramming of cancer cells and on the immune system's capacity to detect such changes in cancer cell metabolism. Specifically, we focus on mevalonate metabolism, which is a target for drug and immune based cancer treatment. PMID:24467965

Gruenbacher, Georg; Thurnher, Martin

2015-01-28

356

Eicosanoids in Metabolic Syndrome  

PubMed Central

Chronic persistent inflammation plays a significant role in disease pathology of cancer, cardiovascular disease, and metabolic syndrome (MetS). MetS is a constellation of diseases that include obesity, diabetes, hypertension, dyslipidemia, hypertriglyceridemia, and hypercholesterolemia. Nonalcoholic fatty liver disease (NAFLD) is associated with many of the MetS diseases. These metabolic derangements trigger a persistent inflammatory cascade, which includes production of lipid autacoids (eicosanoids) that recruit immune cells to the site of injury and subsequent expression of cytokines and chemokines that amplify the inflammatory response. In acute inflammation, the transcellular synthesis of antiinflammatory eicosanoids resolve inflammation, while persistent activation of the autacoid-cytokine-chemokine cascade in metabolic disease leads to chronic inflammation and accompanying tissue pathology. Many drugs targeting the eicosanoid pathways have been shown to be effective in the treatment of MetS, suggesting a common linkage between inflammation, MetS and drug metabolism.The cross-talk between inflammation and MetS seems apparent because of the growing evidence linking immune cell activation and metabolic disorders such as insulin resistance, dyslipidemia, and hypertriglyceridemia. Thus modulation of lipid metabolism through either dietary adjustment or selective drugs may become a new paradigm in the treatment of metabolic disorders. This review focuses on the mechanisms linking eicosanoid metabolism to persistent inflammation and altered lipid and carbohydrate metabolism in MetS. PMID:23433458

Hardwick, James P.; Eckman, Katie; Lee, Yoon Kwang; Abdelmegeed, Mohamed A.; Esterle, Andrew; Chilian, William M.; Chiang, John Y.; Song, Byoung-Joon

2013-01-01

357

Influences of anionic and cationic dopants on the morphology and optical properties of PbS nanostructures  

NASA Astrophysics Data System (ADS)

Selenium and zinc are used as anionic and cationic dopant elements to dope PbS nanostructures. The undoped and doped PbS nanostructures are grown using a thermal evaporation method. Scanning electron microscopy (SEM) results show similar morphologies for the undoped and doped PbS nanostructures. X-ray diffraction (XRD) patterns of three sets of the nanostructures indicate that these nanostructures each have a PbS structure with a cubic phase. Evidence of dopant incorporation is demonstrated by X-ray photoelectron spectroscopy (XPS). Raman spectra of the synthesized samples confirm the XRD results and indicate five Raman active modes, which relate to the PbS cubic phase for all the nanostructures. Room temperature photoluminescence (PL) and UV—Vis spectrometers are used to study optical properties of the undoped and doped PbS nanostructures. Optical characterization shows that emission and absorption peaks are in the infrared (IR) region of the electromagnetic spectrum for all PbS nanostructures. In addition, the optical studies of the doped PbS nanostructures reveal that the band gap of the Se-doped PbS is smaller, and the band gap of the Zn-doped PbS is bigger than the band gap of the undoped PbS nanostructures.

Ramin, Yousefi; Mohsen, Cheragizade; Farid, Jamali-Sheini; R. Mahmoudian, M.; Abdolhossein, Saaédi; Nay, Ming Huang

2014-10-01

358

Reactivity of hypotaurine and cysteine sulfinic acid toward carbonate radical anion and nitrogen dioxide as explored by the peroxidase activity of Cu,Zn superoxide dismutase and by pulse radiolysis.  

PubMed

Abstract Hypotaurine and cysteine sulfinic acid are known to be readily oxidized to the respective sulfonates, taurine and cysteic acid, by several oxidative agents that may be present in biological systems. In this work, the relevance of both the carbonate anion and nitrogen dioxide radicals in the oxidation of hypotaurine and cysteine sulfinic acid has been explored by the peroxidase activity of Cu,Zn superoxide dismutase (SOD) and by pulse radiolysis. The extent of sulfinate oxidation induced by the system SOD/H2O2 in the presence of bicarbonate (CO3(•-) generation), or nitrite ((•)NO2 generation) has been evaluated. Hypotaurine is efficiently oxidized by the carbonate radical anion generated by the peroxidase activity of Cu,Zn SOD. Pulse radiolysis studies have shown that the carbonate radical anion reacts with hypotaurine more rapidly (k = 1.1 × 10(9) M(-1)s(-1)) than nitrogen dioxide (k = 1.6 × 10(7) M(-1)s(-1)). Regarding cysteine sulfinic acid, it is less reactive with the carbonate radical anion (k = 5.5 × 10(7) M(-1)s(-1)) than hypotaurine. It has also been observed that the one-electron transfer oxidation of both sulfinates by the radicals is accompanied by the generation of transient sulfonyl radicals (RSO2(•)). Considering that the carbonate radical anion could be formed in vivo at high level from bicarbonate, this radical can be included in the oxidants capable of performing the last metabolic step of taurine biosynthesis. Moreover, the protective effect exerted by hypotaurine and cysteine sulfinate on the carbonate radical anion-mediated tyrosine dimerization indicates that both sulfinates have scavenging activity towards the carbonate radical anion. However, the formation of transient reactive intermediates during sulfinate oxidation by carbonate anion and nitrogen dioxide radical may at the same time promote oxidative reactions. PMID:25156684

Baseggio Conrado, A; D'Angelantonio, M; Torreggiani, A; Pecci, L; Fontana, M

2014-11-01

359

Gap Formation in Circumbinary AGN Disks  

NASA Astrophysics Data System (ADS)

We numerically study the formation of gaps in circumbinary disks of comparable mass massive black hole binaries (q ˜ 1). We vary the disk properties (mass, thermodynamics, etc.) and found that most massive and thicker disks are able to prevent the gap formation in them. We contrast our results against analytical models based on the non-axisymetric perturbation enhanced in the disk, which succesfully predicts the disks that opens a gap. We discuss the implications for the occurence of opened and failed gaps in the final separations and posible merging of binary AGNs.

Escala, A.; Del Valle, L.

2014-10-01

360

Redefining yield gaps at various spatial scales  

NASA Astrophysics Data System (ADS)

Recent research has highlighted the prevalence of 'yield gaps' around the world and the importance of closing them for global food security. However, the traditional concept of yield gap -defined as the difference between observed and optimal yield under biophysical conditions - omit relevant socio-economic and ecological constraints and thus offer limited guidance on potential policy interventions. This paper proposes alternative definitions of yield gaps by incorporating rich, high resolution, national and sub-national agricultural datasets. We examine feasible efforts to 'close yield gaps' at various spatial scales and across different socio-economic and ecological domains.

Meng, K.; Fishman, R.; Norstrom, A. V.; Diekert, F. K.; Engstrom, G.; Gars, J.; McCarney, G. R.; Sjostedt, M.

2013-12-01

361

New distributional modelling approaches for gap analysis  

E-print Network

Synthetic products based on biodiversity information such as gap analysis depend critically on accurate models of species' geographic distributions that simultaneously minimize error in both overprediction and omission. ...

Peterson, A. Townsend; Kluza, D. A.

2003-02-01

362

Large-gap magnetic suspension systems  

NASA Technical Reports Server (NTRS)

The classification of magnetic suspension devices into small-gap and large-gap categories is addressed. The relative problems of position sensing, control systems, power supplies, electromagnets, and magnetic field or force analysis are discussed. The similarity of all systems from a controls standpoint is qualified. Some applications where large-gap technology is being applied to systems with a physically small air-gap are mentioned. Finally, the applicability of some other suspension approaches, such as electrodynamic or superconducting are briefly addressed.

Britcher, Colin P.

1992-01-01

363

Relationship Between Equilibrium Forms of Lysozyme Crystals and Precipitant Anions  

NASA Technical Reports Server (NTRS)

Molecular forces, such as electrostatic, hydrophobic, van der Waals and steric forces, are known to be important in determining protein interactions. These forces are affected by the solution conditions and changing the pH, temperature or the ionic strength of the solution can sharply affect protein interactions. Several investigations of protein crystallization have shown that this process is also strongly dependent on solution conditions. As the ionic strength of the solution is increased, the initially soluble protein may either crystallize or form an amorphous precipitate at high ionic strengths. Studies done on the model protein hen egg white lysozyme have shown that different crystal forms can be easily and reproducibly obtained, depending primarily on the anion used to desolubilize the protein. In this study we employ pyranine to probe the effect of various anions on the water structure. Additionally, lysozyme crystallization was carried out at these conditions and the crystal form was determined by X-ray crystallography. The goal of the study was to understand the physico-chemical basis for the effect of changing the anion concentration on the equilibrium form of lysozyme crystals. It will also verify the hypothesis that the anions, by altering the bulk water structure in the crystallizing solutions, alter the surface energy of the between the crystal faces and the solution and, consequently, the equilibrium form of the crystals.

Nadarajah, Arunan

1996-01-01

364

COMMUNICATIONS Photoelectron imaging spectroscopy of molecular and cluster anions  

E-print Network

the simultaneous observation of photoelectron energy spectra and energy- resolved photoelectron angularCOMMUNICATIONS Photoelectron imaging spectroscopy of molecular and cluster anions: CS2 Ã? and OCSÃ?, Arizona 85721-0041 Received 7 January 2002; accepted 14 February 2002 We report the photoelectron imaging

Sanov, Andrei

365

Pharmacogenomics of organic anion-transporting polypeptides (OATP)  

Microsoft Academic Search

The organic anion-transporting polypeptides (OATP) represent a family of proteins responsible for the membrane transport of a large number of endogenous and xenobiotic compounds with diverse chemical characteristics. OATPs are expressed in liver, kidney, brain and intestine suggesting that they may play a critical role in drug disposition. Naturally occurring polymorphisms in OATPs are currently being identified and for some,

Rommel G Tirona; Richard B Kim

2002-01-01

366

Removal of bromide and natural organic matter by anion exchange  

Microsoft Academic Search

Bromide removal by anion exchange was explored for various water qualities, process configurations, and resin characteristics. Simulated natural waters containing different amounts of natural organic matter (NOM), bicarbonate, chloride, and bromide were treated with a polyacrylate-based magnetic ion exchange (MIEX) resin on a batch basis to evaluate the effectiveness of the resin for removal of bromide. While bromide removal was

Susan Hsu; Philip C. Singer

2010-01-01

367

The role of catalyst precursor anions in coal gasification  

Microsoft Academic Search

The aims of the proposed project are to enrich our understanding of the roles of various aqueous soluble catalyst precursor anions on the surface electrical properties of coal and to ascertain the influence of the surface charge on the adsorption, dispersion, and activities of calcium and potassium. These goals will be achieved by impregnating a demineralized North Dakota lignite (PSOC

Abotsi; G. M. K

1992-01-01

368

Superoxide Anions and Endothelial Cell Proliferation in Normoglycemia and Hyperglycemia  

E-print Network

and by Western analysis and SOD activity assay in AdCuZnSOD-transduced cells. Superoxide production diabetes mellitus superoxide dismutase Although oxygen-derived free radicals have been impli- catedSuperoxide Anions and Endothelial Cell Proliferation in Normoglycemia and Hyperglycemia Michela

Engelhardt, John F.

369

Regulation of organic anion transport in the liver.  

PubMed

In several liver diseases the biliary transport is disturbed, resulting in, for example, jaundice and cholestasis. Many of these symptoms can be attributed to altered regulation of hepatic transporters. Organic anion transport, mediated by the canalicular multispecific organic anion transporter (cmoat), has been extensively studied. The regulation of intracellular vesicular sorting of cmoat by protein kinase C and protein kinase A, and the regulation of cmoat-mediated transport in endotoxemic liver disease, have been examined. The discovery that the multidrug resistance protein (MRP), responsible for multidrug resistance in cancers, transports similar substrates as cmoat led to the cloning of a MRP homologue from rat liver, named mrp2. Mrp2 turned out to be identical to cmoat. At present there is evidence that at least two mrp's are present in hepatocytes, the original mrp (mrp1) on the lateral membrane, and mrp2 (cmoat) on the canalicular membrane. The expression of mrp1 and mrp2 in hepatocytes appears to be cell-cycle-dependent and regulated in a reciprocal fashion. These findings show that biliary transport of organic anions and possibly other canalicular transport is influenced by the entry of hepatocytes into the cell cycle. The cloning of the gene for cmoat opens up new possibilities to study the regulation of hepatic organic anion transport. PMID:9626764

Roelofsen, H; Müller, M; Jansen, P L

1997-01-01

370

Tetrathiafulvalene diindolylquinoxaline: a dual signaling anion receptor with phosphate selectivity†  

PubMed Central

Incorporation of tetrathiafulvalene into the backbone of a known neutral phosphate receptor, diindolylquinoxaline, yields a dual optical-electrochemical chemosensor for dihydrogen phosphate that functions in dichloromethane. This system shows selectivity for dihydrogen phosphate over other small anions and can be used to detect the presence of this analyte via fluorescence quenching or cyclic voltammetry. PMID:20856940

Bejger, Christopher; Park, Jung Su; Silver, Eric S.; Sessler, Jonathan L.

2011-01-01

371

Bound anionic states of adenine Maciej Haran czyk  

E-print Network

and in charge transfer through DNA. Previous gas phase studies of free, unsolvated nucleic acid base parent be formed in the course of dissociative electron attachment followed by a hydrogen atom attachment of adenine was facilitated by the development of (i) an experimental method for preparing parent anions

Simons, Jack

372

Cation and anion sequences in dark-adapted Balanus photoreceptor  

PubMed Central

Anion and cation permeabilities in dark-adapted Balanus photoreceptors were determined by comparing changes in the membrane potential in response to replacement of the dominant anion (Cl-) or cation (Na+) by test anions or cations in the superfusing solution. The anion permeability sequence obtained was PI greater than PSO4 greater than PBr greater than PCl greater than Pisethionate greater than Pmethanesulfonate. Gluconate, glucuronate, and glutamate generally appeared more permeable and propionate less permeable than Cl-. The alkali-metal cation permeability sequence obtained was PK greater than PRb greater than PCx greater than PNa approximately PLi. This corresponds to Eisenman's IV which is the same sequencethat has been obtained for other classes of nerve cells in the resting state. The values obtained for the permeability ratios of the alkali-metal cations are considered to be minimal. The membrane conductance measured by passing inward current pulses in the different test cations followed the sequence, GK greater than GRb greater than GCs greater than GNa greater than GLi. The conductance ratios obtained for a full substitution of the test cation agreed quite well with permeability ratios for all the alkali-metal cations except K+ which was generally higher. PMID:199688

1977-01-01

373

Characterization of anion exchange membranes fouled with humate during electrodialysis  

Microsoft Academic Search

Fouling tendencies during electrodialysis (ED) can be determined by the electrochemical and physical properties of the foulants and ion exchange membranes. In this study, the fouling characteristics of anion exchange membranes were investigated according to their electric resistances, hydrophobicities, exchange capacities and zeta potentials. In order to correlate the fouling potential with the properties of the foulant (humate), the zeta

Hong-Joo Lee; Jae-Hwan Choi; Jaeweon Cho; Seung-Hyeon Moon

2002-01-01

374

Dietary Cation Anion Difference of Five Cool-Season Grasses  

Microsoft Academic Search

Forage-based rations with a low dietary cation anion difference (DCAD) should be fed to dairy cows 2 to 4 wk prepartum to prevent hypocalcaemia or milk fever. We evaluated the DCAD of two to four cultivars of five grass species at three locations in Quebec, Canada. Orchardgrass (Dactylis glomerata L.), meadow bromegrass (Bromus riparius Rehmann), tall fescue (Festuca arundinacea Schreb.),

Gaëtan F. Tremblay; Hélène Brassard; Gilles Bélanger; Philippe Seguin; Raynald Drapeau; Annie Brégard; Réal Michaud; Guy Allard

2006-01-01

375

Photoelectron spectroscopy of phosphorus hydride anions Kent M. Ervina  

E-print Network

, University of Colorado and National Institute of Standards and Technology, and Department of Chemistry February 2005; published online 13 May 2005 Negative-ion photoelectron spectroscopy is applied to the PH apply negative-ion photoelectron spec- troscopy to a series of phosphorus hydride anions, PH- , PH2

Lineberger, W. Carl

376

Engineering of anion-deficient perovskites by laser MBE  

NASA Astrophysics Data System (ADS)

The flexibility of the ABO3 perovskite structure and its ability to accommodate cationic or anionic vacancies leads to a variety of perovskite-based compounds with versatile physical properties. Recently [1] we reported on the possibility of creating the Ti-rich (sqr13xsqr13)-R33.7deg complex surface reconstruction using PLD layer-by-layer growth manipulation [2]. Usually, the presence of A cations in stoichiometric perovskites favors point defects in the anion sites (in a random or ordered arrangement), but the absence of A cations leads to a lower coordination number for the B cations, and supports the elimination of anion point defects by a crystallographic shear. We studied the propagation of this artificial long-order periodic structure during homogeneous growth of SrTiO3 (STO) on TiO2-terminated and non-treated STO substrates by the combination of high-pressure RHEED, depth-resolved cathodoluminescence, synchrotron x-ray excited photoluminescence, and x-ray absorption spectroscopy. We believe that the observed intergrowth of such complex surface reconstructions over the deposited ultra-thin film might be a way to fabricate layered perovskite-related structures that preserve anion-deficient non-stoichiometry. [4pt] [1] APS March meeting 2011, abstract # T10.008. [0pt] [2] M. Kareev et al., JAP 109, 114303 (2011).

Kareev, Mikhail; Gray, B.; Balaz, S.; Rosenberg, R. A.; Meyers, D.; Moon, E. J.; Liu, J.; Brillson, L. J.; Freeland, J. W.; Chakhalian, J.

2012-02-01

377

Molecular Anions in Protostars, Prestellar Cores and Dark Clouds  

NASA Technical Reports Server (NTRS)

From our recent survey work using the Green Bank Telescope, microwave emission lines from the hydrocarbon anion C6H(-) and its parent neutral C6H have been detected in six new sources. Using HC3N = 10(exp -9) emission maps, we targeted the most carbon-chain-rich sources for our anion survey, which included the low-mass Class 0 protostar L1251A-IRS3, the prestellar cores L1389-SMM1 and L1512, and the interstellar clouds Ll172A, TMC-1C and L1495B. Derived [C6H(-)]/[C6H] anion-to-neutral ratios are approximately 1-10. The greatest C6H(-) column densities are found in the quiescent clouds TMC-1C and L1495B, but the anion-to-neutral ratios are greatest in the prestellar cores and protostars. These results are interpreted in terms of the physical and chemical properties of the sources, and the implications for molecular cloud chemistry are discussed.

Cordiner, Martin; Charnley, Steven; Buckle, Jane; Wash, Catherine; Millar, Tom

2011-01-01

378

The electronic structure of TEMPO, its cation and anion  

NASA Astrophysics Data System (ADS)

The electronic structure of TEMPO (2,2,6,6-tetramethyl-1-piperidinyl N-oxide), its cation and anion were studied experimentally using the following electron spectroscopy techniques: electron energy-loss spec-troscopy (EELS), measurement of elastic and vibrational excitation (VE) cross sections, HeI photoelectron (PE) spectroscopy and dissociative electron attachment (DEA) spectroscopy.

Regeta, Khrystyna; Jane?ková, Radmila; Kubala, Dušan; Fedor, Juraj; Allan, Michael

2014-04-01

379

PHASE BEHAVIOR OF WATER/PERCHLOROETHYLENE/ANIONIC SURFACTANT SYSTEMS  

EPA Science Inventory

Winsor Type I (o/w), Type II (w/o), and Type III (middle phase) microemulsions have been generated for water and perchloroethylene (PCE) in combination with anionic surfactants and the appropriate electrolyte concentration. The surfactant formulation was a combination of sodium d...

380

The Determination of Anionic Surfactants in Natural and Waste Waters.  

ERIC Educational Resources Information Center

Background information, procedures, and results of an experiment suitable for measuring subpart per million concentrations of anionic surfactants in natural waters and waste effluents are provided. The experiment required only a spectrophotometer or filter photometer and has been successfully performed by students in an undergraduate environmental…

Crisp, P. T.; And Others

1983-01-01

381

Anion Binding and Transport by Prodigiosin and Its Analogs  

NASA Astrophysics Data System (ADS)

The red-colored prodiginines, exemplified by prodigiosin 1, are secondary metabolites produced by a number of microorganisms, including the bacterium Serratia marcescens. These tripyrrole natural products and their synthetic analogs have received renewed attention over the past deacade, primarily because of their promising immunosuppressive and anticancer activities. One of the hallmarks of prodiginin chemistry is the ability of the monoprotonated ligand to bind anions, including the essential chloride and bicarbonate ions. The resulting lipophilic ion pair is then able to diffuse across the hydrophobic barrier presented by phospholipid bilayers. Thus, prodiginines have been found to be potent transmembrane anion transporters and HCl cotransporters. In this chapter, the author reviews what is known about the solid-state structure of prodiginins and their anion complexes, the solution conformation of prodiginines, and the biochemcal evidence for the ability to bind anions and to transport HCl across cell membranes. Recent progress in making synthetic models of prodiginines and recent results on the ability of prodigiosin to transport HCO 3 - across lipid membranes are discussed.

Davis, Jeffery T.

382

Resonance States of Atomic Anions ALEXEI V. SERGEEV, SABRE KAIS  

E-print Network

Resonance States of Atomic Anions ALEXEI V. SERGEEV, SABRE KAIS Department of Chemistry, Purdue with decrease of its nuclear charge. By analytic continuation from bound to resonance states, we obtain complex Quantum Chem 82: 255­261, 2001 Key words: resonance states; negative ions; complex rotation method

Kais, Sabre

383

Effect of tumor promoting stimuli on gap junction permeability and connexin 43 expression in ARL 18 rat liver cell line  

Microsoft Academic Search

The ARL18 rat liver cell line has previously been used for screening tumor promoters in the metabolic cooperation assay (Williams 1980; Williams et al. 1981; Telang et al. 1982). These cells display high levels of gap junctional communication, as assessed functionally and immunologically. Intracellularly injected Lucifer Yellow diffused extensively and there was rapid fluorescent recovery after photobleaching. Moreover, expression of

Irina V. Budunovat; Gary M. Williams; David C. Spray

1993-01-01

384

INTERACTIVE EFFECTS OF ALDRIN, CYCLOHEXYLAMINE, 2,4-DIAMINOTOLUENE AND TWO PHORBAL ESTERS ON METABOLIC COOPERATION BETWEEN V79 CELLS  

EPA Science Inventory

The in vitro V79/metabolic cooperation assay measures the extent of gap-junctional transfer of metabolites from wild-type to mutant V79 cells. he assay is currently being explored as a short-term test to screen for tumor promoting chemicals, many of which inhibit metabolic cooper...

385

Trimethylsilyl derivatization of nucleic acid anions in the gas phase  

NASA Astrophysics Data System (ADS)

Ion-molecule reactions between nucleic acid anions, [M-nH]n, formed via electrospray ionization, and trimethylsilylchloride have been investigated in an ion trap mass spectrometer at a helium bath gas pressure of 1 mtorr. Three types of reactions are observed: (i) SN2(Si) when n > 1 ; (ii) adduct formation when n = 1 ; and (iii) addition followed by elimination of HCl when n = 1 and where an acidic phosphate proton is present (e.g., 5'-pdA). The kinetics of these reactions have been studied for various anions derived from the following deoxyadenosine species: 5'-pdA; 5'-pppdA, 5'-d(AA)-3'; 5'-d(AAA)-3' and 5'-d(AAAA)-3'. The following reactivity order is observed: [M-2H]2- of 5'-pppdA > [M-2H]2- of 5'-d(AAA)-3' > [M-3H]3- of 5'-d(AAAA)-3' > [M-3H + TMS]2- of 5'-d(AAAA)-3' > [M-2H]2- of 5'-d(AAAA)-3' > [M-H]- of 5'-pdA >> [M-H]- of 5'-d(AA)-3' > [M-H]- of 5'-d(AAA)-3'. In addition, the collision-induced dissociation reactions of the products of these reactions have been studied. Decomposition reactions are consistent with trimethylsilyl attachment on the phosphodiester linkage(s) in oligonucleotides and on the phosphate moieties of 5'-pdA and 5'-pppdA. Comparison of data acquired for modified and unmodified oligonucleotide anions of the same charge state reveal that TMS modification can significantly alter the favored dissociation channels, giving rise to sequence information. The results suggest that gas phase TMS derivatization of oligonucleotide anions, combined with tandem mass spectrometry, can provide sequence information complementary to that derived from unmodified anions.

O'Hair, Richard A. J.; McLuckey, Scott A.

1997-03-01

386

A new ion-selective electrode for anionic surfactants.  

PubMed

The new ligand 7-methyl-7,13-di-octyl-1,4,10-trioxa-13-aza-7-azonia-cyclopentadecane (L(1)) has been designed, synthesised and used as ionophore in the development ion-selective electrodes for anionic surfactants. Different PVC-membrane anionic-surfactants-selective electrodes were prepared by using L(1) as ionophore and bis(2-ethylhexyl)sebacate (BEHS), dibutyl phthalate (DBP) and nitrophenyl octyl ether (NPOE) as plasticizers. The PVC-membrane electrode containing L(1) and NPOE (electrode E1) showed a Nernstian response to lauryl sulfate with a slope of -59.5mV per decade in a range of concentrations from 1.3x10(-6) to 6.8x10(-3)M and a detection limit of 6.0x10(-7)M. The electrode E1 also showed a reasonable response to other alkyl sulfates and alkylbenzene sulfonates, whereas it does not respond to carboxylates and to cationic and non-ionic surfactants. A similar electrode to E1 but additionally containing the cationic additive n-octylammonium bromide was also prepared (electrode E2) and compared with the response of E1. Selectivity coefficients for different anions with respect to lauryl sulfate were determined by means of the fixed interference method considering lauryl sulfate as the principal anion and using a concentration of 1.0x10(-2)moldm(-3) for the corresponding interfering anion. The selectivity sequence found for the electrode E1 was: LS(-)>SCN(-)>ClO(4)(-)>CH(3)COO(-)>I(-)>HCO(3)(-)>Br(-)>NO(3)(-)>NO(2)(-)>Cl(-)>IO(3)(-)>phosphate>SO(3)(2-)>C(2)O(4)(2-)>SO(4)(2-). Electrode E1 showed remarkably better selectivity coefficients than electrode E2. PMID:19071308

Seguí, M A Jesús; Lizondo-Sabater, Josefa; Benito, Angel; Martínez-Máñez, Ramón; Pardo, Teresa; Sancenón, Félix; Soto, Juan

2007-01-15

387

Direct band gap wurtzite GaP nanowires for LEDs and quantum devices  

NASA Astrophysics Data System (ADS)

Commercially available light-emitting diodes (LEDs) suffer from low-efficiency in the green region of the visible spectrum. In order to solve this issue III-V materials such as Gallium phosphide (GaP) can be investigated. GaP in the zinc blende (ZB) crystal structure has an indirect band gap, limiting the efficiency of the green emission. However, when the material is grown with wurtzite (WZ) crystal phase a direct band gap is predicted. Here, we show the fabrication and the characterization of wurtzite GaP nanowires, together with the demonstration of the direct band gap. The strong photoluminescence signal observed at 594 nm with a lifetime in the order of 1ns matches with the expectation for a direct band gap material. Furthermore, the emission wavelength can be tuned across a wide range of the visible spectrum (555-690 nm) by incorporating aluminum or arsenic in the WZ GaP nanowires.

Assali, S.; Kriegner, D.; Zardo, I.; Plissard, S.; Verheijen, M. A.; Stangl, J.; Haverkort, J. E. M.; Bakkers, E. P. A. M.

2014-09-01

388

One Gap. Two Gaps. Universality in High Temperature Superconductors  

NASA Astrophysics Data System (ADS)

One of the goals in contemporary condensed matter physics, is to understand various emergent properties of matter due to many body interactions --- e.g. superfluidity, superconductivity, colossal magnetoresistance and so on. Superconductors, discovered more than a century ago, have the remarkable property of zero resistance to electrical current below certain temperatures, commonly known as critical temperatures (Tc). The Tc value for conventional superconductor is relatively low, less than 30K, while it could be as high as 150K for a new class of materials, known as high temperature superconductors (HTSCs). The mechanism behind superconductivity in conventional superconductors can be well understood under the framework of the famous BCS (Bardeen, Cooper, Schrieffer) theory, while for HTSCs, it is still a mystery. Angle Resolved Photoemission Spectroscopy (ARPES), which directly probes the momentum space structure of a physical system, has been instrumental to provide new insights in understanding various strongly correlated systems --- particularly the HTSC materials. In this thesis, I will present and discuss our recent research on various Bi2212 HTSCs using ARPES. For the first time, we provided the spectroscopic evidence for the three distinct phases in the normal state of Bi2212 HTSC. By comparing the systematic ARPES data of pure Bi2212 and cation-doped Bi2212 HTSCs, we found that introducing different elements would not only change the carrier concentration, but also create additional disorders inside the system, which is responsible for the different spectroscopic properties. In additon, we found that the deviation from d-wave gap anisotropy in cation-doped Bi2212 is correlated to the lack of coherent spectral peaks. I will also give an overview of the synthesis of La-doped Bi2212 single crystals by using floating zone technique. Even though the La content varies along the crystal growth direction, our crystals are of the pure Bi2212 crystal structure, and their carrier concentrations are in the underdoped side of the superconducting dome.

Zhao, Junjing

389

Addressing the vaccine confidence gap.  

PubMed

Vaccines--often lauded as one of the greatest public health interventions--are losing public confidence. Some vaccine experts have referred to this decline in confidence as a crisis. We discuss some of the characteristics of the changing global environment that are contributing to increased public questioning of vaccines, and outline some of the specific determinants of public trust. Public decision making related to vaccine acceptance is neither driven by scientific nor economic evidence alone, but is also driven by a mix of psychological, sociocultural, and political factors, all of which need to be understood and taken into account by policy and other decision makers. Public trust in vaccines is highly variable and building trust depends on understanding perceptions of vaccines and vaccine risks, historical experiences, religious or political affiliations, and socioeconomic status. Although provision of accurate, scientifically based evidence on the risk-benefit ratios of vaccines is crucial, it is not enough to redress the gap between current levels of public confidence in vaccines and levels of trust needed to ensure adequate and sustained vaccine coverage. We call for more research not just on individual determinants of public trust, but on what mix of factors are most likely to sustain public trust. The vaccine community demands rigorous evidence on vaccine efficacy and safety and technical and operational feasibility when introducing a new vaccine, but has been negligent in demanding equally rigorous research to understand the psychological, social, and political factors that affect public trust in vaccines. PMID:21664679

Larson, Heidi J; Cooper, Louis Z; Eskola, Juhani; Katz, Samuel L; Ratzan, Scott

2011-08-01

390

NEN Division Funding Gap Analysis  

SciTech Connect

The work in NEN Division revolves around proliferation detection. The sponsor funding model seems to have shifted over the last decades. For the past three lustra, sponsors are mainly interested in funding ideas and detection systems that are already at a technical readiness level 6 (TRL 6 -- one step below an industrial prototype) or higher. Once this level is reached, the sponsoring agency is willing to fund the commercialization, implementation, and training for the systems (TRL 8, 9). These sponsors are looking for a fast turnaround (1-2 years) technology development efforts to implement technology. To support the critical national and international needs for nonprolifertion solutions, we have to maintain a fluent stream of subject matter expertise from the fundamental principals of radiation detection through prototype development all the way to the implementation and training of others. NEN Division has large funding gaps in the Valley of Death region. In the current competitive climate for nuclear nonproliferation projects, it is imminent to increase our lead in this field.

Esch, Ernst I. [Los Alamos National Laboratory; Goettee, Jeffrey D. [Los Alamos National Laboratory; Desimone, David J. [Los Alamos National Laboratory; Lakis, Rollin E. [Los Alamos National Laboratory; Miko, David K. [Los Alamos National Laboratory

2012-09-05

391

METABOLISM OF CARBAMATE INSECTICIDES  

EPA Science Inventory

The results of studies conducted to determine the metabolic fate of carbamate insecticides and its toxicological significance are presented. Methomyl metabolism in rats was investigated in detail as was Croneton in the rat, cow, pig and chicken. Carbaryl and carbofuran were admin...

392

Metabolic rate measurement system  

NASA Technical Reports Server (NTRS)

The Metabolic Rate Measurement System (MRMS) is an uncomplicated and accurate apparatus for measuring oxygen consumption and carbon dioxide production of a test subject. From this one can determine the subject's metabolic rate for a variety of conditions, such as resting or light exercise. MRMS utilizes an LSI/11-03 microcomputer to monitor and control the experimental apparatus.

Koester, K.; Crosier, W.

1980-01-01

393

Investigation of Anion-pi Interactions in Inorganic, Organic and Biological Systems  

E-print Network

Despite an ever growing number of reports concerning the anion-? interaction, controversy surrounding the nature of these weak supramolecular interactions continues. In an effort to further explore the nature and properties of anion-? interactions...

Funck, Edward Sterling

2012-07-16

394

Lithium Diisopropylamide-Mediated Ortholithiation and Anionic Fries Rearrangement of Aryl Carbamates: Role of  

E-print Network

Lithium Diisopropylamide-Mediated Ortholithiation and Anionic Fries Rearrangement of Aryl of the lithium diisopropylamide (LDA)-mediated anionic Fries rearrangements of aryl carbamates are described, an LDA-lithium phenolate mixed dimer, and homoaggregated lithium phenolates. The highly insoluble

Collum, David B.

395

Characterization of anion diffusion in polymer hydrogels used for wastewater remediation  

E-print Network

Characterization of anion diffusion in polymer hydrogels used for wastewater remediation Dimitri R pollutants, even at extremely low concentrations, from wastewater effluents are a major environmental need of reactive phosphorus, nitrogen, and sulfur anions from aquaculture production wastewater effluents

Rubloff, Gary W.

396

Roles of Two Types of Anion Channels in Glutamate Release from Mouse Astrocytes Under Ischemic  

E-print Network

Roles of Two Types of Anion Channels in Glutamate Release from Mouse Astrocytes Under Ischemic University, Tashkent 700095, Vuzgorodok, Uzbekistan KEY WORDS astrocyte; anion channels; glutamate release; osmotic stress; swelling; ischemia ABSTRACT Astrocytes release glutamate upon hyperexcitation

Newman, Eric A.

397

Thermal decomposition of GAP and GAP-based double-base propellants  

Microsoft Academic Search

This paper reports the thermal decomposition pattern of GAP and GAP-containing double-base (DB) compositions. Dynamic and isothermal TGA reveal a two-stage decomposition process for GAP. At temperatures below 200°C reactant-product interface diffusion, while at higher temperatures nucleation-based diffusion processes appear to be operative. Inclusion of GAP resulted in a drop in temperature for the onset of freeradical reaction.

S. S. Dhar; S. N. Asthana; H. Singh; G. N. Natu

1993-01-01

398

Metabolism of halophilic archaea  

PubMed Central

In spite of their common hypersaline environment, halophilic archaea are surprisingly different in their nutritional demands and metabolic pathways. The metabolic diversity of halophilic archaea was investigated at the genomic level through systematic metabolic reconstruction and comparative analysis of four completely sequenced species: Halobacterium salinarum, Haloarcula marismortui, Haloquadratum walsbyi, and the haloalkaliphile Natronomonas pharaonis. The comparative study reveals different sets of enzyme genes amongst halophilic archaea, e.g. in glycerol degradation, pentose metabolism, and folate synthesis. The carefully assessed metabolic data represent a reliable resource for future system biology approaches as it also links to current experimental data on (halo)archaea from the literature. Electronic supplementary material The online version of this article (doi:10.1007/s00792-008-0138-x) contains supplementary material, which is available to authorized users. PMID:18278431

Falb, Michaela; Muller, Kerstin; Konigsmaier, Lisa; Oberwinkler, Tanja; Horn, Patrick; von Gronau, Susanne; Gonzalez, Orland; Pfeiffer, Friedhelm; Bornberg-Bauer, Erich

2008-01-01

399

Metabolic Engineering VII Conference  

SciTech Connect

The aims of this Metabolic Engineering conference are to provide a forum for academic and industrial researchers in the field; to bring together the different scientific disciplines that contribute to the design, analysis and optimization of metabolic pathways; and to explore the role of Metabolic Engineering in the areas of health and sustainability. Presentations, both written and oral, panel discussions, and workshops will focus on both applications and techniques used for pathway engineering. Various applications including bioenergy, industrial chemicals and materials, drug targets, health, agriculture, and nutrition will be discussed. Workshops focused on technology development for mathematical and experimental techniques important for metabolic engineering applications will be held for more in depth discussion. This 2008 meeting will celebrate our conference tradition of high quality and relevance to both industrial and academic participants, with topics ranging from the frontiers of fundamental science to the practical aspects of metabolic engineering.

Kevin Korpics

2012-12-04

400

Delaying the Academy: A Gap Year Education  

ERIC Educational Resources Information Center

This investigation serves as one of the first empirical analyses to examine the international volunteering gap year from an educational perspective, concluding an in-depth case study of a prominent gap year organisation in the UK. Contrary to widespread industry promotion of international development, the findings suggest that the experience can…

O'Shea, Joseph

2011-01-01

401

THE VECTOR CALCULUS GAP: MATHEMATICS ? PHYSICS  

Microsoft Academic Search

We discuss some of the differences between the way mathematicians and physicists view vector calculus. These differences have led to a gap between the way this material is traditionally taught by mathematicians and the way physicists use it. We also give some suggestions for narrowing the gap.

Tevian Dray; Corinne A. Manogue

1999-01-01

402

THE VECTOR CALCULUS GAP: Mathematics = Physics  

E-print Network

THE VECTOR CALCULUS GAP: Mathematics = Physics Tevian Dray Department of Mathematics, Oregon State discuss some of the differences between the way mathematicians and physicists view vector calculus and the way physicists use it. We also give some suggestions for narrowing the gap. Keywords: vector calculus

403

Public Perceptions of the Pay Gap  

ERIC Educational Resources Information Center

Women have made gains toward closing the gender pay gap during the past two decades. Much of the progress occurred during the 1980s, with smaller gains in the 1990s (Institute for Women's Policy Research 2004). Women's achievements in higher education are partly responsible for narrowing the pay gap in the 1980s and 1990s. As more women earned…

Hill, Catherine; Silva, Elena

2005-01-01

404

Drop short control of electrode gap  

DOEpatents

During vacuum consumable arc remelting the electrode gap between a consumable electrode and a pool of molten metal is difficult to control. The present invention monitors drop shorts by detecting a decrease in the voltage between the consumable electrode and molten pool. The drop shorts and their associated voltage reductions occur as repetitive pulses which are closely correlated to the electrode gap. Thus, the method and apparatus of the present invention controls electrode gap based upon drop shorts detected from the monitored anode-cathode voltage. The number of drop shorts are accumulated, and each time the number of drop shorts reach a predetermined number, the average period between drop shorts is calculated from this predetermined number and the time in which this number is accumulated. This average drop short period is used in a drop short period electrode gap model which determines the actual electrode gap from the drop short. The actual electrode gap is then compared with a desired electrode gap which is selected to produce optimum operating conditions and the velocity of the consumable error is varied based upon the gap error. The consumable electrode is driven according to any prior art system at this velocity. In the preferred embodiment, a microprocessor system is utilized to perform the necessary calculations and further to monitor the duration of each drop short. If any drop short exceeds a preset duration period, the consumable electrode is rapidly retracted a predetermined distance to prevent bonding of the consumable electrode to the molten remelt.

Fisher, Robert W. (Albuquerque, NM); Maroone, James P. (Albuquerque, NM); Tipping, Donald W. (Albuquerque, NM); Zanner, Frank J. (Sandia Park, NM)

1986-01-01

405

Subgroup Achievement and Gap Trends: Mississippi, 2010  

ERIC Educational Resources Information Center

This paper profiles the student subgroup achievement and gap trends in Mississippi for 2010. Mississippi made changes to its state testing program in the 2007-08 school year. Therefore, subgroup and achievement gap trends could not be calculated because fewer than three consecutive years of data were available, too short a period to constitute a…

Center on Education Policy, 2010

2010-01-01

406

Subgroup Achievement and Gap Trends: Idaho, 2010  

ERIC Educational Resources Information Center

This paper profiles the student subgroup achievement and gap trends in Idaho for 2010. Idaho showed improvement in reading and math in grade 8 at the basic, proficient, and advanced levels for Latino and white students, low income students, and boys and girls. The state has also made progress in narrowing achievement gaps between Latino and white…

Center on Education Policy, 2010

2010-01-01

407

Is the Gender Gap in Unemployment Disappearing?  

NSF Publications Database

Is The Gender Gap In Unemployment Disappearing? This Issue Brief contrasts trends in the gender gap in unemployment among doctoral scientists and engineers with trends in the larger labor force and examines the question of whether marriage and children have different effects on unemployment among men and women. See Help for more information about viewing publications in different formats.

408

College major choice and the gender gap  

Microsoft Academic Search

Males and females are markedly different in their choice of college major. Two main reasons have been suggested for the gender gap: differences in innate abilities and differences in preferences. This paper addresses the question of how college majors are chosen, focusing on the underlying gender gap. Since observed choices may be consistent with many combinations of expectations and preferences,

Basit Zafar

2009-01-01

409

Logarithmic gap costs decrease alignment accuracy  

Microsoft Academic Search

BACKGROUND: Studies on the distribution of indel sizes have consistently found that they obey a power law. This finding has lead several scientists to propose that logarithmic gap costs, G (k) = a + c ln k, are more biologically realistic than affine gap costs, G (k) = a + bk, for sequence alignment. Since quick and efficient affine costs

Reed A. Cartwright

2006-01-01

410

Pain, qualia, and the explanatory gap  

Microsoft Academic Search

This paper investigates the status of the purported explanatory gap between pain phenomena and natural science, when the “gap” is thought to exist due to the special properties of experience designated by “qualia” or “the pain quale” in the case of pain experiences. The paper questions the existence of such a property in the case of pain by: (1) looking

Don Gustafson

1998-01-01

411

Missouri Regional Skills Gap Initiative Summary Report  

Microsoft Academic Search

The future of the workforce in the West Central Region of Missouri lies in our ability to build the capacity of local businesses to recognize and seek a solution to the skills gaps that exist within our thirteen county region. Skills gaps exist when the existing workforce has lower skill levels than are necessary to meet the objectives of the

Elaine L. Chao

412

Gas mixtures for spark gap closing switches  

DOEpatents

Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches. 6 figs.

Christophorou, L.G.; McCorkle, D.L.; Hunter, S.R.

1987-02-20

413

Reusable Thermal Barrier for Insulation Gaps  

NASA Technical Reports Server (NTRS)

Filler composed of resilient, heat-resistant materials. Thermal barrier nestles snugly in gap between two tiles with minimal protrusion beyond faces of surrounding tiles. When removed from gap, barrier springs back to nearly original shape. Developed for filling spaces between tiles on Space Shuttle, also used in furnaces and kilns.

Saladee, C. E.

1985-01-01

414

Gender pay gap and its perceptions  

Microsoft Academic Search

Purpose – The purpose of this paper is to broaden the domain of the gender pay gap research by exploring individuals' perceptions of it. Examining the factors that have an impact on the way individuals perceive the gender pay gap helps answering the question of why it persists and how to overcome it. Design\\/methodology\\/approach – The paper provides a conceptual

Violetta Khoreva

2011-01-01

415

Closing the Gender Gap: Act Now  

ERIC Educational Resources Information Center

Gender gaps are pervasive in all walks of economic life and imply large losses in terms of foregone productivity and living standards to the individuals concerned and the economy. This new OECD report focuses on how best to close these gender gaps under four broad headings: (1) Gender equality, social norms and public policies; and gender equality…

OECD Publishing (NJ3), 2012

2012-01-01

416

Formation and cleavage of aromatic disulfide radical anions.  

PubMed

The electron transfer (ET) to a series of para-substituted diaryl disulfides, having the general formula (X-C(6)H(4)S-)(2), has been studied. The X groups were selected as to have a comprehensive variation of the substituent effect, being X = NH(2), MeO, H, F, Cl, CO(2)Et, CN, and NO(2). The reduction was carried out experimentally, using N,N-dimethylformamide as the solvent, and by molecular orbital (MO) ab initio calculations. The ET was studied heterogeneously, by voltammetric reduction and convolution analysis, and homogeneously, by using electrogenerated radical anions as the solution electron donors. The reduction is dissociative, leading to the cleavage of the S-S bond in a stepwise manner. Both experimental approaches led us to estimate the E degrees and the intrinsic barrier values for the formation of the radical anions. Comparison of the independently obtained results allowed obtaining, for the first time, a quantitative description of the correlation between heterogeneous and homogeneous rate constants of ETs associated with significant inner reorganization energy. The experimental outcome was fully supported by the theoretical calculations, which provided information about the disulfide lowest unoccupied MOs (LUMOs) and singly occupied MO (SOMO), the bond dissociation energies, and the most significant structural modifications associated with radical anion formation. With disulfides bearing electron-donating or mildly electron-withdrawing groups, the inner reorganization is particularly large, which reflects the significant stretching of the S-S bond experienced by the molecule upon ET. The process entails formation of loose radical anion species in which the SOMO is heavily localized, as the LUMO, onto the frangible bond. As a consequence of the formation of these sigma-radical anions, the S-S bond energy of the latter is rather small and the cleavage rate constant is very large. With electron-withdrawing groups, the extent of delocalization of the SOMO onto the aryl system increases, leading to a decrease of the reorganization energy for radical anion formation. Interestingly, while the LUMO now has pi character, the actual reduction intermediate (and thus the SOMO) is still a sigma-type radical anion. With the nitro-substituted disulfide, very limited inner reorganization is required and a pi-radical anion initially forms. A nondissociative type intramolecular ET then ensues, leading to the formation of a new radical anion whose antibonding orbital has similar features as those of the SOMO of the other diaryl disulfides. Therefore, independently of the substituent, the actual S-S bond cleavage occurs in a quite similar way along the series investigated. The S-S bond cleavage rate, however, tends to decrease as the Hammett sigma increases, which would be in keeping with an increase of both the electronic and solvent reorganization energies. PMID:14640668

Antonello, Sabrina; Daasbjerg, Kim; Jensen, Henrik; Taddei, Ferdinando; Maran, Flavio

2003-12-01

417

First observation of a tetra-anionic metal cluster, Al(n)(4-).  

PubMed

The production of aluminum cluster tetra-anions, and thus the first observation of a tetra-anionic metal cluster in the gas-phase, is reported. The aluminum cluster polyanions were generated by use of the "electron-bath technique." The smallest tetra-anion observed was Al(215) (4-), containing 14% fewer atoms than expected from classical estimates of the tetra-anion appearance size. PMID:20078162

Walsh, N; Martinez, F; Marx, G; Schweikhard, L; Ziegler, F

2010-01-01

418

Acoustic Band Gap Formation in Metamaterials  

NASA Astrophysics Data System (ADS)

We present several new classes of metamaterials and/or locally resonant sonic crystal that are comprised of complex resonators. The proposed systems consist of multiple resonating inclusion that correspond to different excitation frequencies. This causes the formation of multiple overlapped resonance band gaps. We demonstrate theoretically and experimentally that the individual band gaps achieved, span a far greater range (? 2kHz) than previously reported cases. The position and width of the band gap is independent of the crystal's lattice constant and forms in the low frequency regime significantly below the conventional Bragg band gap. The broad envelope of individual resonance band gaps is attractive for sound proofing applications and furthermore the devices can be tailored to attenuate lower or higher frequency ranges, i.e., from seismic to ultrasonic.

Elford, D. P.; Chalmers, L.; Kusmartsev, F.; Swallowe, G. M.

2011-03-01

419

Acoustic Band Gap Formation in Metamaterials  

NASA Astrophysics Data System (ADS)

We present several new classes of metamaterials and/or locally resonant sonic crystal that are comprised of complex resonators. The proposed systems consist of multiple resonating inclusion that correspond to different excitation frequencies. This causes the formation of multiple overlapped resonance band gaps. We demonstrate theoretically and experimentally that the individual band gaps achieved, span a far greater range (? 2kHz) than previously reported cases. The position and width of the band gap is independent of the crystal's lattice constant and forms in the low frequency regime significantly below the conventional Bragg band gap. The broad envelope of individual resonance band gaps is attractive for sound proofing applications and furthermore the devices can be tailored to attenuate lower or higher frequency ranges, i.e., from seismic to ultrasonic.

Elford, D. P.; Chalmers, L.; Kusmartsev, F.; Swallowe, G. M.

420

Gap junction proteins in the blood-brain barrier control nutrient-dependent reactivation of Drosophila neural stem cells.  

PubMed

Neural stem cells in the adult brain exist primarily in a quiescent state but are reactivated in response to changing physiological conditions. How do stem cells sense and respond to metabolic changes? In the Drosophila CNS, quiescent neural stem cells are reactivated synchronously in response to a nutritional stimulus. Feeding triggers insulin production by blood-brain barrier glial cells, activating the insulin/insulin-like growth factor pathway in underlying neural stem cells and stimulating their growth and proliferation. Here we show that gap junctions in the blood-brain barrier glia mediate the influence of metabolic changes on stem cell behavior, enabling glia to respond to nutritional signals and reactivate quiescent stem cells. We propose that gap junctions in the blood-brain barrier are required to translate metabolic signals into synchronized calcium pulses and insulin secretion. PMID:25065772

Spéder, Pauline; Brand, Andrea H

2014-08-11

421

Water soluble sapphyrins: potential fluorescent phosphate anion sensors.  

PubMed

As part of an ongoing effort to study the anion binding properties of sapphyrins in various media, a number of previously reported water solubilized sapphyrins were studied in methanol and in buffered, neutral aqueous solutions and found to undergo self-aggregation under these solution phase conditions. The nature of the species produced as the result of self-aggregation and the processes leading to their formation were studied via UV-vis absorbance and fluorescence spectroscopy. In previous work (V. Král, H. Furuta, K. Shreder, V. Lynch, and J. L. Sessler, J. Am. Chem. Soc. 1996, 118 1595-1607) it was found that the addition of phosphate-type anions to water soluble sapphyrins at pH 6.1 gives rise to visible spectroscopic changes consistent with the binding to the aggregated form and the concurrent formation of an anion-bound dimer with effective equilibrium constants on the order of 100-300 M(-1). In this study we show that at high phosphate-to-sapphyrin ratios in neutral, buffered aqueous solutions further deaggregation occurs to produce an anion-bound monomeric form. This highly fluorescent species is formed with effective equilibrium constants on the order of 6-19 M(-1) leading to considerations that sapphyrins could function as fluorescent phosphate anion sensors. In an effort to modulate the deaggregation properties, several new sapphyrin derivatives bearing two meso aryl substituents were prepared and studied. The aggregation properties of these latter systems were analyzed in methanol and, in the case of one water solublized system, in neutral aqueous media. In analogy to what was observed for the beta-alkyl substituted sapphyrins, H-type aggregates were seen for the water solubilized meso-substituted system in aqueous media. However, in contrast to the H-type dimers seen in the case of the meso-free systems in methanol, J-type dimers were observed in the case of the sapphyrins bearing two meso substituents in this solvent. The effective dimerization constants of several of the meso-diaryl sapphyrins were determined in methanol as were their pKa values in aqueous media. The solid state structure of the bis HBr salt of one of the meso-diaryl sapphyrins, specifically 10,15-bis(3,5-di-tert-butylphenyl)-3,22-diethyl-2,23-dimethylsapphyrin, was also determined and found to show elements in common with those of previously reported sapphyrin derivatives. In particular, the two counter anions were found to be hydrogen bound above and below the diprotonated sapphyrin plane. PMID:14664401

Sessler, Jonathan L; Davis, Julian M; Král, Vladimir; Kimbrough, Thomas; Lynch, Vincent

2003-11-21

422

Anion photoelectron spectroscopy of I2 ,,CO2...n,,n18... clusters  

E-print Network

Received 12 December 2001; accepted 17 January 2002 We report the anion photoelectron spectra of I2 (CO2)n and the neutral cluster formed by photodetachment. In this paper, we report anion photoelectron spectra of I2 (CO2Anion photoelectron spectroscopy of I2 � ,,CO2...n,,n�1­8... clusters Harry Go´mez, Travis R

Neumark, Daniel M.

423

Photoelectron spectroscopy of small IBr-,,CO2...n ,,n=03... cluster anions  

E-print Network

We report the photoelectron spectra of small IBr- CO2 n cluster anions n=0­3 . The vibrational state with recent theoretical studies. The photoelectron spectra of the first three cluster anions, IBr- CO2 n n=1Photoelectron spectroscopy of small IBr- ,,CO2...n ,,n=0­3... cluster anions Leonid Sheps, Elisa M

Lineberger, W. Carl

424

Poly( o-anisidine)–anion composite films as sensing platform for biological molecules  

Microsoft Academic Search

Polyanisidine films doped with two different anions, viz., perchlorate and paratoluene sulphonate anions are prepared electrochemically on a gold substrate. Polyanisidine films doped with the anions aid in retaining the redox conductivity of the polyanisidine films. This behaviour is similar to that of polyaniline films. Unlike polyaniline films, even smaller ions like perchlorate and paratoluene sulphonate are sufficient for retaining

B. Angaleeswari; R. M. Dura Amirtham; T. Jeevithaa; V. Vaishnavi; T. Eevera; Sheela Berchmans; V. Yegnaraman

2008-01-01

425

Indirect photometric ion chromatographic analysis of anions in Haematococcus pluvialis culture media  

Microsoft Academic Search

An indirect photometric ion chromatographic method for the simultaneous determination of chloride, nitrate and sulfate ions was developed and applied to the determination of anions, mainly nitrate, in the alga Haematococcus pluvialis culture media. Using phthalic acid\\/sodium tetraborate aqueous solution as the mobile phase, anions can be detected indirectly by a UV detector. The calibration curves for these anions gave

Jian-Ping Yuan; Feng Chen

2001-01-01

426

Elicitor-induced chloride efflux and anion channels in tobacco cell suspensions  

Microsoft Academic Search

Membrane depolarization associated with changes in transmembrane cation and anion effluxes constitute early events in the signalling cascades which mediate elicitor-induced defense reactions in plant cells. The aim of the present study is to investigate whether membrane depolarization can be a key step in the signalling cascade by triggering the opening of voltage-dependent anion channels which would mediate anion effluxes.

Sabine Zimmermann; Jean-Marie Frachisse; Sébastien Thomine; Hélène Barbier-Brygoo; Jean Guern

1998-01-01

427

On the binding of electrons to nitromethane: Dipole and valence bound anions  

E-print Network

On the binding of electrons to nitromethane: Dipole and valence bound anions R. N. Comptona) and H when the molecule possesses a lower energy valence anion configuration as well as a dipole-bound state valence and dipole-bound anions of the nitromethane molecule are studied using negative ion photoelectron

Simons, Jack

428

A bidentate Lewis acid with a telluronium ion as an anion-binding site  

Microsoft Academic Search

The search for receptors that can selectively capture small and potentially toxic anions in protic media has sparked a renewed interest in the synthesis and anion-binding properties of polydentate Lewis acids. Seeking new paradigms to enhance the anion affinities of such systems, we synthesized a bidentate Lewis acid that contains a boryl and a telluronium moiety as Lewis acidic sites.

Haiyan Zhao; François P. Gabbaï

2010-01-01

429

Crystal growth and characterization of the narrow-band-gap semiconductors OsPn? (Pn = P, As, Sb).  

PubMed

Using metal fluxes, crystals of the binary osmium dipnictides OsPn2 (Pn = P, As, Sb) have been grown for the first time. Single-crystal X-ray diffraction confirms that these compounds crystallize in the marcasite structure type with orthorhombic space group Pnnm. The structure is a three-dimensional framework of corner- and edge-sharing OsPn6 octahedra, as well as [Pn2(4-)] anions. Raman spectroscopy shows the presence of P-P single bonds, consistent with the presence of [Pn2(-4)] anions and formally Os(4+) cations. Optical-band-gap and high-temperature electrical resistivity measurements indicate that these materials are narrow-band-gap semiconductors. The experimentally determined Seebeck coefficients reveal that nominally undoped OsP2 and OsSb2 are n-type semiconductors, whereas OsAs2 is p-type. Electronic band structure using density functional theory calculations shows that these compounds are indirect narrow-band-gap semiconductors. The bonding p orbitals associated with the Pn2 dimer are below the Fermi energy, and the corresponding antibonding states are above, consistent with a Pn-Pn single bond. Thermopower calculations using Boltzmann transport theory and constant relaxation time approximation show that these materials are potentially good thermoelectrics, in agreement with experiment. PMID:25162930

Bugaris, Daniel E; Malliakas, Christos D; Shoemaker, Daniel P; Do, Dat T; Chung, Duck Young; Mahanti, Subhendra D; Kanatzidis, Mercouri G

2014-09-15

430

A "light-on" colorimetric assay for anion detection using the inhibitory effect of anions on the catalytic activity of metal nanoparticles for the degradation of methyl orange.  

PubMed

In this communication, we studied the inhibitory effects of anions on the catalytic activity of metal nanoparticles for the degradation of methyl orange (MO). Some anions have great affinity with specific metal nanoparticles, thus resulting in the change of surface state and inhibition of catalytic activity, which can be observed with the naked eye or manifested in the UV spectrum of MO for anion detection. PMID:25317955

Lu, Lixia; Yang, Fan; Yang, Xiurong

2014-10-27

431

Methyl Halide Cluster Anion Photoelectron Spectra and Angular Distributions as a Probe of Electron-Molecule Interactions.  

E-print Network

??This dissertation describes the development of a method for studying electron &ndash molecule interactions using cluster anion photodetachment. Photodetachment from an atomic centered cluster anion… (more)

Van Duzor, Matthew

2011-01-01

432

Boron substitution in aluminum cluster anions: magic clusters and reactivity with oxygen.  

PubMed

We have studied the size-selective reactivity of AlnBm(-) clusters m = 1,2 with O2 to investigate the effect of congener substitution in energetic aluminum clusters. Mixed-metal clusters offer an additional strategy for tuning the electronic and geometric structure of clusters and by substituting an atom with a congener; we may investigate the effect of structural changes in clusters with similar electronic structures. Using a fast-flow tube mass spectrometer, we formed aluminum boride cluster anions and exposed them to molecular oxygen. We found multiple stable species with Al12B(-) and Al11B2(-) being highly resistant to reactivity with oxygen. These clusters behave in a similar manner as Al13(-), which has previously been found to be stable in oxygen because of its icosahedral geometry and its filled electronic shell. Al13(-) and Al12B(-) have icosahedral structures, while Al11B2(-) forms a distorted icosahedron. All three of these clusters have filled electronic shells, and Al12B(-) has a larger HOMO-LUMO gap due to its compact geometry. Other cluster sizes are investigated, and the structures of the AlnB(-) series are found to have endohedrally doped B atoms, as do many of the AlnB2(-) clusters. The primary etching products are found to be a loss of two Al2O molecules, with boron likely to remain in the cluster. PMID:24725222

Smith, Jordan C; Reber, Arthur C; Khanna, Shiv N; Castleman, A W

2014-09-18

433

Metabolic disharmony and mortality.  

PubMed

The concept of 'metabolic harmony' is introduced and conceptualized as the state in which indices of metabolic activity (i.e., serum glucose, cholesterol, systolic and diastolic blood pressure, body mass index) within an individual attain their expected values given the individual values on related variables. Its complement, 'metabolic disharmony' (i.e., the extent to which an individual's 'profile' of metabolic variables is jointly unusual in relation to their expected values) is operationalized via Mahalanbis' D(2 )statistic calculated on these indices of metabolic activity (plus age and sex). Analysis of a large (N = 5209) longitudinal (32 years) cohort study shows that, independent of the linear and quadratic effects of the aforementioned metabolic variables, the disharmony index (DI) significantly and strongly predicted hazard of death (chi(2)(1) = 20.05, P < 0.00005). That is, each 10 percentile increase in DI was associated with a 6.9% increase in the hazard rate. The association of DI to hazard rate was not materially altered when potential confounders (e.g., smoking status) were added to the model or when all subjects were included by imputing missing data. These results demonstrate that metabolic disharmony is associated with, and may cause, an increased hazard of death. PMID:11388775

Allison, D B; Fontaine, K R; Cheskin, L J

2001-05-01

434

Targeting cancer metabolism.  

PubMed

The understanding that oncogenes can have profound effects on cellular metabolism and the discovery of mutations and alterations in several metabolism-related enzymes--isocitrate dehydrogenase 1 (IDH1), isocitrate dehydrogenase 2 (IDH2), succinate dehydrogenase (SDH), fumarate hydratase (FH), and pyruvate kinase M2 (PKM2)--has renewed interest in cancer metabolism and renewed hope of taking therapeutic advantage of cancer metabolism. Otto Warburg observed that aerobic glycolysis was a characteristic of cancer cells. More than 50 years later, we understand that aerobic glycolysis and uptake of glutamine and glycine allow cancer cells to produce energy (ATP) and the nucleotides, amino acids, and lipids required for proliferation. Expression of the MYC oncogene drives the increase in cellular biomass facilitating proliferation. PKM2 expression in cancer cells stimulates aerobic glycolysis. Among intermediary metabolism enzymes, mutations in SDH occur in gastointestinal stromal tumors and result in a pseudohypoxic metabolic milieu. FH mutations lead to a characteristic renal cell carcinoma. Isocitrate dehydrogenase (IDH1/2) mutations have been found in leukemias, gliomas, prostate cancer, colon cancer, thyroid cancer, and sarcomas. These recently recognized oncogenic metabolic lesions may be selective targets for new anticancer therapeutics. PMID:23071355

Teicher, Beverly A; Linehan, W Marston; Helman, Lee J

2012-10-15

435

Personality and metabolic syndrome.  

PubMed

The prevalence of metabolic syndrome has paralleled the sharp increase in obesity. Given its tremendous physical, emotional, and financial burden, it is of critical importance to identify who is most at risk and the potential points of intervention. Psychological traits, in addition to physiological and social risk factors, may contribute to metabolic syndrome. The objective of the present research is to test whether personality traits are associated with metabolic syndrome in a large community sample. Participants (N = 5,662) from Sardinia, Italy, completed a comprehensive personality questionnaire, the NEO-PI-R, and were assessed on all components of metabolic syndrome (waist circumference, triglycerides, high-density lipoprotein cholesterol, blood pressure, and fasting glucose). Logistic regressions were used to predict metabolic syndrome from personality traits, controlling for age, sex, education, and current smoking status. Among adults over age 45 (n = 2,419), Neuroticism and low Agreeableness were associated with metabolic syndrome, whereas high Conscientiousness was protective. Individuals who scored in the top 10% on Conscientiousness were approximately 40% less likely to have metabolic syndrome (OR = 0.61, 95% CI = 0.41-0.92), whereas those who scored in the lowest 10% on Agreeableness were 50% more likely to have it (OR = 1.53, 95% CI = 1.09-2.16). At the facet level, traits related to impulsivity and hostility were the most strongly associated with metabolic syndrome. The present research indicates that those with fewer psychological resources are more vulnerable to metabolic syndrome and suggests a psychological component to other established risk factors. PMID:20567927

Sutin, Angelina R; Costa, Paul T; Uda, Manuela; Ferrucci, Luigi; Schlessinger, David; Terracciano, Antonio

2010-12-01

436

The noble resists composed of cationic and anionic polymerizable PAGs  

NASA Astrophysics Data System (ADS)

A recent new class of resists referred to as polymer-bound PAG resists, which have slightly increased PAG loading and reduced photo acid diffusion relative to tranditional blended CAR systems have shown promise in improving resolution, faster photospeed, higher stablility and LER. we have developed two kinds of PAG, which are cationic and anionic polymerizable PAGs. One is that the polymer backbone is directly connected with cationic part in PAG and the other is that the polymer backbone is directly connected with anionic part in PAG. In this study we described the synthetic process of polymerizable PAGs and the polymerization process to make PAG-bound polymers and then, the lithography properties of resists composed of PAG-bound polymer were reffed to.

Oh, Jung Hoon; Seo, Dong Chul; Joo, Hyun Sang; Jung, Sung Do; Kim, Jin Ho; Lee, Seung Jae; Park, Ran Ra; Han, JoonHee; Park, Joo Hyeon

2008-11-01

437

Anionic Emulsion-Mediated Synthesis of Zeolite Beta  

NASA Astrophysics Data System (ADS)

Well-crystallized zeolite beta is first synthesized in the anionic emulsion systems of cyclohexane/sodium dodecylbenzenesulfonate(SDBS)/pentanol/zeolite synthesis mixture. Beta materials are then characterized by XRD, SEM, and N2-adsorption techniques. Compared to beta samples grown using the same synthesis mixture in the absence of the anionic emulsion, the as-synthesized beta presents uniform and well-defined larger crystals. Interestingly, N2-adsorption results show that such beta sample possesses both ordered mesopores at 3.9 nm and macropores centered at 60.5 nm. These pores combined with the intricate micropores of the Beta crystal comprise the hierarchical porosity. The hierarchical pore-structured zeolite beta may have potential catalysis application in reactions involving large molecules. Additionally, control experiments are also performed to ascertain the effects of the individual emulsion components. Further synthesis study finds the transformation of zeolite beta to ZSM-5 through increasing oil contents, crystallization temperature and time.

Jin, Chao; Zhang, Ying; Gao, Wei; Cui, Lishan

438

Local impermeant anions establish the neuronal chloride concentration.  

PubMed

Neuronal intracellular chloride concentration [Cl(-)](i) is an important determinant of ?-aminobutyric acid type A (GABA(A)) receptor (GABA(A)R)-mediated inhibition and cytoplasmic volume regulation. Equilibrative cation-chloride cotransporters (CCCs) move Cl(-) across the membrane, but accumulating evidence suggests factors other than the bulk concentrations of transported ions determine [Cl(-)](i). Measurement of [Cl(-)](i) in murine brain slice preparations expressing the transgenic fluorophore Clomeleon demonstrated that cytoplasmic impermeant anions ([A](i)) and polyanionic extracellular matrix glycoproteins ([A](o)) constrain the local [Cl(-)]. CCC inhibition had modest effects on [Cl(-)](i) and neuronal volume, but substantial changes were produced by alterations of the balance between [A](i) and [A](o). Therefore, CCCs are important elements of Cl(-) homeostasis, but local impermeant anions determine the homeostatic set point for [Cl(-)], and hence, neuronal volume and the polarity of local GABA(A)R signaling. PMID:24503855

Glykys, J; Dzhala, V; Egawa, K; Balena, T; Saponjian, Y; Kuchibhotla, K V; Bacskai, B J; Kahle, K T; Zeuthen, T; Staley, K J

2014-02-01

439

Infrared spectrum and structural assignment of the water trimer anion.  

PubMed

The bending vibrational spectrum of the perdeutero isotopomer of the water trimer anion has been measured and compared with spectra calculated using the MP2, CCSD, and Becke3LYP electronic structure methods. Due to its low electron binding energy (approximately 150 meV), only the OD bending region of the IR spectrum of (D2O)3(-) is accessible experimentally, with electron ejection dominating at higher photon energies. The calculated spectrum of the isomer having three water molecules arranged in a chain agrees best with the experimental spectrum. In the chain isomer, the excess electron is bound to the terminal water monomer with two dangling OH groups. This is consistent with the electron binding mechanism established previously for the (H2O)n(-) (n = 2, 4-6) anions. PMID:16354044

Hammer, N I; Roscioli, J R; Johnson, M A; Myshakin, E M; Jordan, K D

2005-12-22

440

Macrocyclic bis(ureas) as ligands for anion complexation  

PubMed Central

Summary Two macrocyclic bis(ureas) 1 and 2, both based on diphenylurea, have been synthesized. Compound 1 represents the smaller ring with two ethynylene groups as linkers and 2 the larger ring with two butadiynylene groups. On thermal treatment to 130 °C molecule 1 splits up into two dihydroindoloquinolinone (3) molecules. Both compounds 1 and 2 form adducts with polar molecules such as dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) and act as complexing agents towards a series of anions (Cl?, Br?, I?, NO3 ?, HSO4 ?). The crystal structures of 3, 2·2DMSO, 2·2DMF, and of the complex NEt4[Br·2] have been determined. Quantitative investigations of the complexation equilibria were performed via 1H NMR titrations. While 1 is a rather weak complexing agent, the large ring of 2 binds anions with association constants up to log K = 7.93 for chloride ions. PMID:25161744

Kretschmer, Claudia; Dittmann, Gertrud

2014-01-01

441

Anion-exchange resin-based desulfurization process  

SciTech Connect

The University of Tennessee Space Institute (UTSI) has been directed to further develop an anion-exchange, resin-based desulfurization concept. It is necessary that the soluble sulfates of alkali metal sorbents be desulfurized (regenerated) and recycled to make regenerative flue gas desulfurization options more attractive. In order to achieve this, a low-temperature, low-cost desulfurization process to reactivate spent alkali metal sorbents is necessary. UTSI's anion-exchange, resin-based concept is believed to satisfy this requirement. Investigators will perform the following investigations: screening of commercially available resins; process variables study and improving resin performance; optimization of resin-regeneration; evaluation of performance enhancers; development of Best-Process Schematic and related economics; and planing for proof-of-concept (POC) scale testing. 2 refs., 3 figs., 3 tabs.

Sheth, A.C.; Strevel, S.D.

1991-01-01

442

Metabolic Pathways of Biochemistry  

NSDL National Science Digital Library

George Washington University provides an online reference of the major metabolic pathways for biochemistry students and scientists. Students can learn about carbohydrate, lipid, and energy metabolism with the help of two- and three-dimensional graphics. The website offers representations of generalized organic reactions to illustrate how to convert one functional group to another group. Users can also find a list of over 250 common abbreviations used in biochemistry. Biochemistry students having difficulty conceiving the dimensionality of metabolic pathways will benefit from the materials at this web site.

443

Physiology of iron metabolism.  

PubMed

A revolution occurred during the last decade in the comprehension of the physiology as well as in the physiopathology of iron metabolism. The purpose of this review is to summarize the recent knowledge that has accumulated, allowing a better comprehension of the mechanisms implicated in iron homeostasis. Iron metabolism is very fine tuned. The free molecule is very toxic; therefore, complex regulatory mechanisms have been developed in mammalian to insure adequate intestinal absorption, transportation, utilization, and elimination. 'Ironomics' certainly will be the future of the understanding of genes as well as of the protein-protein interactions involved in iron metabolism. PMID:25053935

Waldvogel-Abramowski, Sophie; Waeber, Gérard; Gassner, Christoph; Buser, Andreas; Frey, Beat M; Favrat, Bernard; Tissot, Jean-Daniel

2014-06-01

444

Circadian Clocks and Metabolism  

PubMed Central

Circadian clocks maintain periodicity in internal cycles of behavior, physiology, and metabolism, enabling organisms to anticipate the 24-h rotation of the Earth. In mammals, circadian integration of metabolic systems optimizes energy harvesting and utilization across the light/dark cycle. Disruption of clock genes has recently been linked to sleep disorders and to the development of cardiometabolic disease. Conversely, aberrant nutrient signaling affects circadian rhythms of behavior. This chapter reviews the emerging relationship between the molecular clock and metabolic systems and examines evidence that circadian disruption exerts deleterious consequences on human health. PMID:23604478

Marcheva, Biliana; Ramsey, Kathryn M.; Peek, Clara B.; Affinati, Alison; Maury, Eleonore; Bass, Joseph

2014-01-01

445

The treatment gap in mental health care.  

PubMed Central

Mental disorders are highly prevalent and cause considerable suffering and disease burden. To compound this public health problem, many individuals with psychiatric disorders remain untreated although effective treatments exist. We examine the extent of this treatment gap. We reviewed community-based psychiatric epidemiology studies that used standardized diagnostic instruments and included data on the percentage of individuals receiving care for schizophrenia and other non-affective psychotic disorders, major depression, dysthymia, bipolar disorder, generalized anxiety disorder (GAD), panic disorder, obsessive-compulsive disorder (OCD), and alcohol abuse or dependence. The median rates of untreated cases of these disorders were calculated across the studies. Examples of the estimation of the treatment gap for WHO regions are also presented. Thirty-seven studies had information on service utilization. The median treatment gap for schizophrenia, including other non-affective psychosis, was 32.2%. For other disorders the gap was: depression, 56.3%; dysthymia, 56.0%; bipolar disorder, 50.2%; panic disorder, 55.9%; GAD, 57.5%; and OCD, 57.3%. Alcohol abuse and dependence had the widest treatment gap at 78.1%. The treatment gap for mental disorders is universally large, though it varies across regions. It is likely that the gap reported here is an underestimate due to the unavailability of community-based data from developing countries where services are scarcer. To address this major public health challenge, WHO has adopted in 2002 a global action programme that has been endorsed by the Member States. PMID:15640922

Kohn, Robert; Saxena, Shekhar; Levav, Itzhak; Saraceno, Benedetto

2004-01-01

446

Generalized diatomics-in-molecules method for polyatomic anions  

Microsoft Academic Search

The diatomics-in-molecules (DIM) method for the construction of polyatomic potential-energy functions from the potential energies of atomic and diatomic fragments is generalized to obtain a description of potential-energy functions of both quasistationary and bound states of polyatomic anions. The formulation is based on the combination of the DIM method with the projection-operator approach of scattering theory. The proposed theory allows

A. K. Belyaev; A. S. Tiukanov; W. Domcke

2002-01-01

447

Cation--anion balance in lime-induced chlorosis. [Soybeans  

Microsoft Academic Search

Lime-induced chlorosis in plants is characterized by some phenomena which fit into a simple hypothesis that internal pH balance is upset due to shifts in cation-anion balances. These pH changes result in precipitation of Fe in plants and fit our previous hypothesis of competitive chelation as an explanation of the multiple causes of lime-induced chlorosis. The oft-times higher concentrations of

A. Wallace; R. A. Wood; S. M. Soufi

1976-01-01

448

Cation?anion balance in lime?induced chlorosis  

Microsoft Academic Search

Lime?induced chlorosis in plants is characterized by some phenomena which fit into a simple hypothesis that internal pH balance is upset due to shifts in cation?anion balances. These pH changes result in precipitation of Fe in plants and fit our previous hypothesis of competitive dictation as an explanation of the multiple causes of lime?induced chlorosis. The oft?times higher concentrations of

A. Wallace; R. A. Wood; S. M. Soufi

1976-01-01