Sample records for anion gap metabolic

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

    PubMed

    Vichot, Alfred A; Rastegar, Asghar

    2014-10-01

    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

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

    PubMed Central

    Venkatram, Sindhaghatta; Diaz-Fuentes, Gilda

    2014-01-01

    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

  3. Successfully Treated Calcific Uremic Arteriolopathy: Two Cases of a High Anion Gap Metabolic Acidosis with Intravenous Sodium Thiosulfate

    PubMed Central

    Rein, Joshua L.; Miyata, Kana N.; Dadzie, Kobena A.; Gruber, Steven J.; Sulica, Roxana; Winchester, James F.

    2014-01-01

    Calcific uremic arteriolopathy (CUA) is a rare and potentially fatal disorder of calcification involving subcutaneous small vessels and fat in patients with renal insufficiency. We describe the successful use of intravenous sodium thiosulfate (STS) for the treatment of CUA in two patients. The first case was complicated by the development of a severe anion gap metabolic acidosis, which was accompanied by a seizure. Both patients had complete wound healing within five months. Although STS should be considered in the treatment of CUA, little is known about pharmacokinetics and additional studies are required to determine dosing strategies to minimize severe potential side effects. PMID:25506005

  4. Strong ion gap: A methodology for exploring unexplained anions

    Microsoft Academic Search

    John A. Kellum; David J. Kramer; Michael R. Pinsky

    1995-01-01

    Purpose: This paper describes the calculation of the strong ion gap (SIG), a physical chemical methodology similar to the anion gap (AG), as a measure of the anion\\/cation balance exclusive of sodium, potassium, chloride, and bicarbonate. We compared the SIG and AG methodologies in three groups of subjects with and without unexplained anions. These groups were (1) healthy volunteers with

  5. The Serum Anion Gap in the Evaluation of Acid-Base Disorders: What Are Its Limitations and Can Its Effectiveness Be Improved?

    PubMed Central

    Nagami, Glenn T.

    2013-01-01

    Summary The serum anion gap has been utilized to identify errors in the measurement of electrolytes, to detect paraproteins, and, most relevant to the nephrologist, to evaluate patients with suspected acid-base disorders. In regard to the latter purpose, traditionally an increased anion gap is identified when it exceeds the upper limit of normal for a particular clinical laboratory measurement. However, because there is a wide range of normal values (often 8–10 mEq/L), an increase in anion concentration can be present in the absence of an increased anion gap. In addition, the type of retained anion can affect the magnitude of the increase in anion gap relative to change in serum [HCO3?] being greater with lactic acidosis compared with ketoacidosis. This review examines the methods of calculation of the serum anion gap in textbooks and published literature, the effect of perturbations other than changes in acid-base balance, and its effectiveness in identifying mild and more severe disturbances in acid-base balance. Limitations of the present methods of determining the normal anion gap and change in the anion gap are highlighted. The possibility of identifying the baseline value for individuals to optimize the use of the calculation in the detection of metabolic acidosis is suggested. PMID:23833313

  6. Near-fatal persistent anion- and osmolal-gap acidosis due to massive gamma-butyrolactone/ethanol intoxication.

    PubMed

    Heytens, Luc; Neels, Hugo; Van Regenmortel, Niels; van den Brink, Wim; Henckes, Manu; Schouwers, Sofie; Dockx, Greet; Crunelle, Cleo L

    2015-03-01

    We report a case of an ethanol and massive gamma-butyrolactone (GBL) intoxication, the precursor of the recreational drug gamma-hydroxybutyric acid (GHB), resulting in life-threatening metabolic acidosis (pH 6.5) with a highly increased anion- and osmolal gap. Rapid analysis using gas chromatography revealed a GHB plasma concentration of 4400?mg/L, far above the upper limit concentration of 1000?mg/L found in adult fatalities attributed to GBL. Full recovery was established following supportive treatment including haemodialysis. This is the first report of a combined ethanol/GBL intoxication as a cause of high serum anion- and osmolal-gap metabolic acidosis. PMID:25205856

  7. The Anion Gap and Routine Serum Protein Measurements in Monoclonal Gammopathies

    PubMed Central

    Joseph, Rosy E.; Gaughan, William J.; McBride, Laura; Bilotti, Elizabeth; McNeill, Ann; Schmidt, Linda; Schillen, Danielle; Siegel, David S.

    2011-01-01

    Summary Background and objectives An abnormal anion gap and an increased total protein and globulin are clues to the diagnosis of monoclonal gammopathy. We explored the utility of these markers in IgG, IgA, IgM, and free light chain monoclonal gammopathies. Design, Setting, Participants, & Measurements The anion gap, Na+ – (Cl– + HCO3–), corrected for hypoalbuminemia, was calculated in patients with monoclonal gammopathies. Exclusion criteria were serum calcium >10.5 mg/dl and/or creatinine >2 mg/dl. Results Among 287 patients, 242 remained after applying exclusion criteria (109 IgG, 64 IgA, 21 IgM, and 48 light chain); 36% of 242 patients required correction for hypoalbuminemia. The anion gap was decreased (<10) in 22% of IgG and increased (>15) in 31% of IgA monoclonal gammopathies. IgM did not affect the gap. In light chain gammopathies, the anion gap showed no consistent trend (15% increased, 17% decreased). Mean clonal IgG, IgA, and IgM concentrations were 10-fold higher than mean clonal free light chain concentrations in the respective monoclonal gammopathies (P < 0.001). These paraprotein level disparities were reflected in significantly increased mean serum total protein and globulin concentrations in IgG, IgA, and IgM versus free light chain monoclonal gammopathies, where mean total protein and globulin levels were within normal limits (P < 0.001). Conclusions The anion gap was significantly altered in IgG and IgA monoclonal gammopathies, but it was not a sensitive tool for suspecting the diagnosis. In light chain monoclonal gammopathies, the anion gap, total protein, and globulin did not provide reliable diagnostic clues. PMID:22157711

  8. A retrospective analysis of glycol and toxic alcohol ingestion: utility of anion and osmolal gaps

    PubMed Central

    2012-01-01

    Background Patients ingesting ethylene glycol, isopropanol, methanol, and propylene glycol ('toxic alcohols') often present with non-specific signs and symptoms. Definitive diagnosis of toxic alcohols has traditionally been by gas chromatography (GC), a technique not commonly performed on-site in hospital clinical laboratories. The objectives of this retrospective study were: 1) to assess the diagnostic accuracy of the osmolal gap in screening for toxic alcohol ingestion and 2) to determine the common reasons other than toxic alcohol ingestion for elevated osmolal gaps. Methods Electronic medical records from an academic tertiary care medical center were searched to identify all patients in the time period from January 1, 1996 to September 1, 2010 who had serum/plasma ethanol, glucose, sodium, blood urea nitrogen, and osmolality measured simultaneously, and also all patients who had GC analysis for toxic alcohols. Detailed chart review was performed on all patients with osmolal gap of 9 or greater. Results In the study period, 20,669 patients had determination of serum/plasma ethanol and osmolal gap upon presentation to the hospitals. There were 341 patients with an osmolal gap greater than 14 (including correction for estimated contribution of ethanol) on initial presentation to the medical center. Seventy-seven patients tested positive by GC for one or more toxic alcohols; all had elevated anion gap or osmolal gap or both. Other than toxic alcohols, the most common causes for an elevated osmolal gap were recent heavy ethanol consumption with suspected alcoholic ketoacidosis, renal failure, shock, and recent administration of mannitol. Only 9 patients with osmolal gap greater than 50 and no patients with osmolal gap greater than 100 were found to be negative for toxic alcohols. Conclusions Our study concurs with other investigations that show that osmolal gap can be a useful diagnostic test in conjunction with clinical history and physical examination. PMID:22240170

  9. Anion Gap Toxicity in Alloxan Induced Type 2 Diabetic Rats Treated with Antidiabetic Noncytotoxic Bioactive Compounds of Ethanolic Extract of Moringa oleifera

    PubMed Central

    2014-01-01

    Moringa oleifera (MO) is used for a number of therapeutic purposes. This raises the question of safety and possible toxicity. The objective of the study was to ascertain the safety and possible metabolic toxicity in comparison with metformin, a known drug associated with acidosis. Animals confirmed with diabetes were grouped into 2 groups. The control group only received oral dose of PBS while the test group was treated with ethanolic extract of MO orally twice daily for 5-6 days. Data showed that the extract significantly lowered glucose level to normal values and did not cause any significant cytotoxicity compared to the control group (P = 0.0698); there was no gain in weight between the MO treated and the control groups (P > 0.8115). However, data showed that treatment with an ethanolic extract of MO caused a decrease in bicarbonate (P < 0.0001), and more than twofold increase in anion gap (P < 0.0001); metformin treatment also decreased bicarbonate (P < 0.0001) and resulted in a threefold increase in anion gap (P < 0.0001). Conclusively, these data show that while MO appears to have antidiabetic and noncytotoxic properties, it is associated with statistically significant anion gap acidosis in alloxan induced type 2 diabetic rats. PMID:25548560

  10. Anion Gap Toxicity in Alloxan Induced Type 2 Diabetic Rats Treated with Antidiabetic Noncytotoxic Bioactive Compounds of Ethanolic Extract of Moringa oleifera.

    PubMed

    Omabe, Maxwell; Nwudele, Chibueze; Omabe, Kenneth Nwobini; Okorocha, Albert Egwu

    2014-01-01

    Moringa oleifera (MO) is used for a number of therapeutic purposes. This raises the question of safety and possible toxicity. The objective of the study was to ascertain the safety and possible metabolic toxicity in comparison with metformin, a known drug associated with acidosis. Animals confirmed with diabetes were grouped into 2 groups. The control group only received oral dose of PBS while the test group was treated with ethanolic extract of MO orally twice daily for 5-6 days. Data showed that the extract significantly lowered glucose level to normal values and did not cause any significant cytotoxicity compared to the control group (P = 0.0698); there was no gain in weight between the MO treated and the control groups (P > 0.8115). However, data showed that treatment with an ethanolic extract of MO caused a decrease in bicarbonate (P < 0.0001), and more than twofold increase in anion gap (P < 0.0001); metformin treatment also decreased bicarbonate (P < 0.0001) and resulted in a threefold increase in anion gap (P < 0.0001). Conclusively, these data show that while MO appears to have antidiabetic and noncytotoxic properties, it is associated with statistically significant anion gap acidosis in alloxan induced type 2 diabetic rats. PMID:25548560

  11. Recurrent Anion Gap Acidosis: An Unusual Presentation of X-Linked Adrenoleukodystrophy in a Five-year-old Male

    PubMed Central

    Schwab, Joel; Pena, Loren; Sigman, Laura; Waggoner, Darrel

    2010-01-01

    We are presenting a five-year-old male with recurrent anion gap acidosis. During his last admission, it was detected that he had elevated VLCFA and the evaluation discovered that he had X-linked Adrenooleukodystrophy. He had the Addisonian only phenotype without any clinical or radiographic CNS findings. We were unable to find any other reports of this presentation of ALD. If the work-up of recurrent anion gap acidosis does not uncover an etiology, X-linked ALD should be considered in the differential diagnosis. PMID:23926373

  12. Warburg Revisited: Regulation of Mitochondrial Metabolism by Voltage-Dependent Anion Channels in Cancer Cells

    PubMed Central

    Maldonado, Eduardo N.

    2012-01-01

    The bioenergetics of cancer cells is characterized by a high rate of aerobic glycolysis and suppression of mitochondrial metabolism (Warburg phenomenon). Mitochondrial metabolism requires inward and outward flux of hydrophilic metabolites, including ATP, ADP and respiratory substrates, through voltage-dependent anion channels (VDACs) in the mitochondrial outer membrane. Although VDACs were once considered to be constitutively open, closure of the VDAC is emerging as an adjustable limiter (governator) of mitochondrial metabolism. Studies of VDACs reconstituted into planar lipid bilayers show that tubulin at nanomolar concentrations decreases VDAC conductance. In tumor cell lines, microtubule-destabilizing agents increase cytoplasmic free tubulin and decrease mitochondrial membrane potential (??m), whereas microtubule stabilization increases ??m. Tubulin-dependent suppression of ??m is further potentiated by protein kinase A activation and glycogen synthase kinase-3? inhibition. Knockdown of different VDAC isoforms, especially of the least abundant isoform, VDAC3, also decreases ??m, cellular ATP, and NADH/NAD+, suggesting that VDAC1 and VDAC2 are most inhibited by free tubulin. The brake on mitochondrial metabolism imposed by the VDAC governator probably is released when spindles form and free tubulin decreases as cells enter mitosis, which better provides for the high ATP demands of chromosome separation and cytokinesis. In conclusion, tubulin-dependent closure of VDACs represents a new mechanism contributing to the suppression of mitochondrial metabolism in the Warburg phenomenon. PMID:22700429

  13. Asymmetric Carbamoyl Anion Additions to Chiral N-Phosphonyl Imines via the GAP Chemistry Process and Stereoselectivity Enrichments.

    PubMed

    Seifert, Cole W; Pindi, Suresh; Li, Guigen

    2014-12-01

    Carbamoyl anions were found to smoothly react with chiral N-phosphonyl imines in toluene at -78 °C to r.t. using LiHMDS as the base. Group-assisted purification (GAP) has been utilized to give the pure amides without using column chromatography or recrystallization. The asymmetric reaction resulted in chiral N-phosphonyl amino amides with good to excellent yields (71-99%) and good crude diastereoselectivities (dr 84:16-95:5). In this GAP procedure, the crude solids are washed with diethyl ether to afford the pure products, as revealed by (1)H NMR analysis; GAP washing consistently increases the diastereopurity of the products, resulting in excellent diastereoselectivities, often with final dr > 99:1. Interestingly, the diastereoenriched products can be obtained either in the ether solution or as the suspended solid, depending on the substrate. PMID:25458404

  14. Effect of the Independent Acid Base Variables on Anion Gap Variation in Cardiac Surgical Patients: A Stewart-Figge Approach

    PubMed Central

    Keklikoglou, Ilias; Papoti, Sofia; Diminikos, George; Diplaris, Konstantinos

    2014-01-01

    Purpose. To determine the effect of each of independent acid base variables on the anion gap (AG) value in cardiac surgical patients. Methods. This retrospective study involved 128 cardiac surgical patients admitted for postoperative care. The variation of AG (AGvar) between the day of admission and the first postoperative day was correlated via a multiple linear regression model with the respective variations of the independent acid base variables, that is, apparent strong ion difference (SIDa), strong ion gap (SIG), carbon dioxide (PCO2), and albumin and phosphate concentrations. Results. The variations of all the above variables contributed significantly to the prediction of AGvar (adjusted R2 = 0.9999, F = 201890.24, and P < 0.001). According to the standardized coefficients (?),??SIGvar (? = 0.948, P < 0.001), [Albumin]var (? = 0.260, P < 0.001), and [Phosphate]var (? = 0.191, P < 0.001) were the major determinants of AGvar with lesser contributions from SIDa,?var (? = 0.071, P < 0.001) and PCO2,?var (? = ?0.067, P < 0.001). Conclusions. All the independent acid base variables contribute to the prediction of the AG value. However, albumin and phosphate and SIG variations seem to be the most important predictors, while AG appears to be rather stable with changes in PCO2 and SIDa. PMID:24688446

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

    PubMed Central

    2012-01-01

    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

  16. A 44-year-old woman with metabolic acidosis, high anion gap, and delayed neurologic deterioration.

    PubMed

    Vakil, Abhay; Upadhyay, Hinesh; Sherani, Khalid; Cervellione, Kelly; Trepeta, Scott; Patel, Mahendra C

    2015-01-01

    A 44-year-old woman was brought to the ED from John F. Kennedy International Airport. The patient was returning with her son from a 3-month visit to Bangladesh. Her journey started with a 4-h flight from Dhaka, Bangladesh to Dubai, United Arab Emirates. She consumed 240 mL of whiskey during the flight. This was followed by a 14-h flight from Dubai to New York. According to the patient's son, she did not consume any alcohol during the second flight. The patient was in her usual state of health with normal mentation throughout her journey. Upon landing, she started complaining of shortness of breath. After disembarking, she was witnessed to have seizure-like activity with involuntary passage of urine, following which she collapsed. The patient was intubated by emergency medical services in the field. PMID:25560868

  17. Effects of anionic salts in a pre-partum dairy ration on calcium metabolism.

    PubMed

    van Dijk, C J; Lourens, D C

    2001-06-01

    The effects of anionic salts in the transition diet on serum and urine calcium at calving and on peripartal health, subsequent milk production and fertility performance were studied in a well-managed, high-producing Friesland dairy herd. Over a period of a year, approximately 21 days before the expected date of calving, 28 pre-partum heifers and 44 multiparous dry cows were randomly allocated within parity to 1 of 2 transition diets, designated control and experimental anionic diets. The anionic diet contained the same quantities of the basic transition ration fed to the control group as well as a standard anionic salt mixture containing 118 g NH4Cl, 36 g (NH4)2SO4 and 68 g MgSO4 (total 222 g) per animal per day. This reduced the DCAD to -11.68 mEq/100 g dietary dry matter compared to +13.57 for the control diet. Blood and urine were randomly sampled from 7 to 8 animals within each category within 3 hours post-partum. Serum calcium (total and ionised) and creatinine, urine calcium and creatinine and the fractional clearance of calcium were assessed. Relevant clinical, milk production, and fertility data were collected. The total serum calcium (2.07 versus 1.60 mmol/l), serum ionised calcium (1.12 vs 1.02 mmol/l), urine calcium (0.92 vs 0.10 mmol/l) and the fractional clearance of calcium (1.88 vs 0.09%) were significantly higher(P <0.01) at calving for multiparous cows fed the anionic diet compared to those fed the control diet. In the primiparous cows there were no significant differences in serum calcium levels. However, the urine calcium (1.07 vs 0.43 mmol/l) and the fractional clearance of calcium was higher (1.75 vs 0.45%) in cows fed the anionic diet (P <0.05 and 0.01 respectively). These results illustrated that there were benefits, although no differences were demonstrated with respect to health, milk production or fertility. The supplementation of diets with anionic salts in the last 2-3 weeks before calving has the potential to significantly improve parturient calcium homeostasis. PMID:11513264

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

    E-print Network

    Neumark, Daniel M.

    Spectroscopy of the low-lying states of the group III­V diatomics, AlP, GaP, InP, and GaAs via anion photodetachment spectroscopy Harry Go´mez, Travis R. Taylor,a) Yuexing Zhao,a) and Daniel M spectroscopy and zero electronic kinetic energy spectroscopy. We observe transitions from the anion 2 and low

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

    PubMed Central

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

    2014-01-01

    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

  20. Deacidification in a plant with crassulacean acid metabolism associated with anion-cation balance

    Microsoft Academic Search

    R. Phillips

    1980-01-01

    In plant tissues using crassulacean acid metabolism (CAM), malate accumulates during the dark and declines in the subsequent light period. The malate is an intermediate store of CO2 which is fixed photosynthetically during the subsequent day and for CAM plants the amplitude of the fluctuation is significant for plant carbon assimilation1. Because they are so considerable, the maximum values for

  1. Bridging the gap between gene expression and metabolic phenotype via kinetic models

    PubMed Central

    2013-01-01

    Background Despite the close association between gene expression and metabolism, experimental evidence shows that gene expression levels alone cannot predict metabolic phenotypes, indicating a knowledge gap in our understanding of how these processes are connected. Here, we present a method that integrates transcriptome, fluxome, and metabolome data using kinetic models to create a mechanistic link between gene expression and metabolism. Results We developed a modeling framework to construct kinetic models that connect the transcriptional and metabolic responses of a cell to exogenous perturbations. The framework allowed us to avoid extensive experimental characterization, literature mining, and optimization problems by estimating most model parameters directly from fluxome and transcriptome data. We applied the framework to investigate how gene expression changes led to observed phenotypic alterations of Saccharomyces cerevisiae treated with weak organic acids (i.e., acetate, benzoate, propionate, or sorbate) and the histidine synthesis inhibitor 3-aminotriazole under steady-state conditions. We found that the transcriptional response led to alterations in yeast metabolism that mimicked measured metabolic fluxes and concentration changes. Further analyses generated mechanistic insights of how S. cerevisiae responds to these stresses. In particular, these results suggest that S. cerevisiae uses different regulation strategies for responding to these insults: regulation of two reactions accounted for most of the tolerance to the four weak organic acids, whereas the response to 3-aminotriazole was distributed among multiple reactions. Moreover, we observed that the magnitude of the gene expression changes was not directly correlated with their effect on the ability of S. cerevisiae to grow under these treatments. In addition, we identified another potential mechanism of action of 3-aminotriazole associated with the depletion of tetrahydrofolate. Conclusions Our simulation results show that the modeling framework provided an accurate mechanistic link between gene expression and cellular metabolism. The proposed method allowed us to integrate transcriptome, fluxome, and metabolome data to determine and interpret important features of the physiological response of yeast to stresses. Importantly, given its flexibility and robustness, our approach can be applied to investigate the transcriptional-metabolic response in other cellular systems of medical and industrial relevance. PMID:23875723

  2. Theoretical Study on the Microhydration of Atmospherically Important Carbonyl Sulfide in Its Neutral and Anionic Forms: Bridging the Gap between the Bulk and Finite Size Microhydrated Cluster.

    PubMed

    Mondal, Saptarsi; Teja, Avula Uday; Singh, Prashant Chandra

    2015-04-16

    Carbonyl sulfide (OCS) is the most abundant and stable sulfur-containing triatomic gas present in the atmosphere that plays an important role in aerosol formation. Structure, energetics, and photoelectron spectral properties of the microhydrated OCS in its neutral and anionic forms have been studied by using the BP86, B3LYP, and MP2 methods. OCS is linear in the neutral state but bent in the anionic state. Water binds with the OCS through a single hydrogen bond (O-H···O) in the OCS-(H2O)n [n = 1-6], whereas binding of OCS(-) with water takes place through single as well as double hydrogen bonds (O-H···S and O-H···O). Energy decomposition analysis shows that electrostatic and exchange energies are the main contributors to the stabilization energy of the microhydrated OCS and OCS(-) clusters. Detachment as well as solvation energies are calculated with different levels of theory and compared with the existing experimental values. Finally, an analytical expression has been used to obtain the bulk value of the detachment and solvation energies from the existing information on the finite size clusters. The present study reveals that hydration increases the detachment energy of the OCS(-) by 3.2 eV. In the absence of experimental bulk values of the detachment and solvation energies for this system, the values obtained by the solvent-number-dependent theoretical expression will definitely reduce this gap and may be used for the modeling of the OCS in the atmosphere. PMID:25807233

  3. METABOLIC RESPONSES OF TRANSITION HOLSTEIN COWS FED ANIONIC SALTS AND SUPPLEMENTED AT CALVING WITH CALCIUM AND ENERGY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to determine the concentrations of plasma Ca, P, Mg, nonesterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), and glucose in transition cows fed anionic salts prepartum and provided with calcium and energy supplements at calving. The study was conducted on a Fl...

  4. Dysfunction of Organic Anion Transporting Polypeptide 1a1 Alters Intestinal Bacteria and Bile Acid Metabolism in Mice

    Microsoft Academic Search

    Youcai Zhang; Pallavi B. Limaye; Lois D. Lehman-McKeeman; Curtis D. Klaassen

    2012-01-01

    Organic anion transporting polypeptide 1a1 (Oatp1a1) is predominantly expressed in liver and is able to transport bile acids (BAs) in vitro. Male Oatp1a1-null mice have increased concentrations of taurodeoxycholic acid (TDCA), a secondary BA generated by intestinal bacteria, in both serum and livers. Therefore, in the present study, BA concentrations and intestinal bacteria in wild-type (WT) and Oatp1a1-null mice were

  5. Anionic polysaccharides

    Microsoft Academic Search

    Chifumi Fukuda; Otto Kollmar; Thilo Schäfer; Ying-Hua Tian; Martin K. Schilling

    2002-01-01

    In liver preservation, the substitution of the anion Cl- by lactobionic acid (LB) prevents reperfusion edema and extends the preservation time for human livers. We studied the effect of compounds that are structurally related to lactobionic acid: anionic polycarbohydrates (sulfated anionic polysaccharide, SAP, and pentosan polysulfate, PPS) on liver function and leukocyte-endothelial cell interaction in isolated perfusion and liver transplant

  6. Exploring the gap between dynamic and constraint-based models of metabolism

    PubMed Central

    Machado, Daniel; Costa, Rafael S.; Ferreira, Eugénio C.; Rocha, Isabel; Tidor, Bruce

    2012-01-01

    Systems biology provides new approaches for metabolic engineering through the development of models and methods for simulation and optimization of microbial metabolism. Here we explore the relationship between two modeling frameworks in common use namely, dynamic models with kinetic rate laws and constraint-based flux models. We compare and analyze dynamic and constraint-based formulations of the same model of the central carbon metabolism of E. coli. Our results show that, if unconstrained, the space of steady states described by both formulations is the same. However, the imposition of parameter-range constraints can be mapped into kinetically feasible regions of the solution space for the dynamic formulation that is not readily transferable to the constraint-based formulation. Therefore, with partial kinetic parameter knowledge, dynamic models can be used to generate constraints that reduce the solution space below that identified by constraint-based models, eliminating infeasible solutions and increasing the accuracy of simulation and optimization methods. PMID:22306209

  7. The barley anion channel, HvALMT1, has multiple roles in guard cell physiology and grain metabolism.

    PubMed

    Xu, Muyun; Gruber, Benjamin D; Delhaize, Emmanuel; White, Rosemary G; James, Richard A; You, Jiangfeng; Yang, Zhenming; Ryan, Peter R

    2015-01-01

    The barley (Hordeum vulgare) gene HvALMT1 encodes an anion channel in guard cells and in certain root tissues indicating that it may perform multiple roles. The protein localizes to the plasma membrane and facilitates malate efflux from cells when constitutively expressed in barley plants and Xenopus oocytes. This study investigated the function of HvALMT1 further by identifying its tissue-specific expression and by generating and characterizing RNAi lines with reduced HvALMT1 expression. We show that transgenic plants with 18-30% of wild-type HvALMT1 expression had impaired guard cell function. They maintained higher stomatal conductance in low light intensity and lost water more rapidly from excised leaves than the null segregant control plants. Tissue-specific expression of HvALMT1 was investigated in developing grain and during germination using transgenic barley lines expressing the green fluorescent protein (GFP) with the HvALMT1 promoter. We found that HvALMT1 is expressed in the nucellar projection, the aleurone layer and the scutellum of developing barley grain. Malate release measured from isolated aleurone layers prepared from imbibed grain was significantly lower in the RNAi barley plants compared with control plants. These data provide molecular and physiological evidence that HvALMT1 functions in guard cells, in grain development and during germination. We propose that HvALMT1 releases malate and perhaps other anions from guard cells to promote stomatal closure. The likely roles of HvALMT1 during seed development and grain germination are also discussed. PMID:24853664

  8. Bridging the gap: Membrane contact sites in signaling, metabolism, and organelle dynamics

    PubMed Central

    2014-01-01

    Regions of close apposition between two organelles, often referred to as membrane contact sites (MCSs), mostly form between the endoplasmic reticulum and a second organelle, although contacts between mitochondria and other organelles have also begun to be characterized. Although these contact sites have been noted since cells first began to be visualized with electron microscopy, the functions of most of these domains long remained unclear. The last few years have witnessed a dramatic increase in our understanding of MCSs, revealing the critical roles they play in intracellular signaling, metabolism, the trafficking of metabolites, and organelle inheritance, division, and transport. PMID:24958771

  9. [Non-lactic metabolic acidosis].

    PubMed

    Offenstadt, G; Guidet, B; Staikowsky, F

    1990-10-01

    The definition of metabolic acidosis (MA) is a primary decrease in plasma bicarbonate concentration. The visceral consequences are largely dependent on the degree of acidosis and the rapidity of its onset; they have been studied mainly in animal studies and therefore, extrapolation to the clinical situation should be cautious. The MA can be classified in two groups according to whether the anionic serum gap is increased or normal (hyperchloremic acidosis). The etiologies of the first group are lactic acidosis, the cetoacidoses and renal failure. The hyperchloremic acidoses usually result from gastro-intestinal bicarbonate losses; the biochemical diagnosis of rarer causes of hyperchloremic acidosis is facilitated by measuring the serum potassium, urinary pH and the urinary anionic gap. Although all causes of MA must be treated, the use of bicarbonate should be discussed in each individual case. PMID:2237201

  10. Causes of metabolic acidosis in canine hemorrhagic shock: role of unmeasured ions

    PubMed Central

    Bruegger, Dirk; Kemming, Gregor I; Jacob, Matthias; Meisner, Franz G; Wojtczyk, Christoph J; Packert, Kristian B; Keipert, Peter E; Faithfull, N Simon; Habler, Oliver P; Becker, Bernhard F; Rehm, Markus

    2007-01-01

    Introduction Metabolic acidosis during hemorrhagic shock is common and conventionally considered to be due to hyperlactatemia. There is increasing awareness, however, that other nonlactate, unmeasured anions contribute to this type of acidosis. Methods Eleven anesthetized dogs were hemorrhaged to a mean arterial pressure of 45 mm Hg and were kept at this level until a metabolic oxygen debt of 120 mLO2/kg body weight had evolved. Blood pH, partial pressure of carbon dioxide, and concentrations of sodium, potassium, magnesium, calcium, chloride, lactate, albumin, and phosphate were measured at baseline, in shock, and during 3 hours post-therapy. Strong ion difference and the amount of weak plasma acid were calculated. To detect the presence of unmeasured anions, anion gap and strong ion gap were determined. Capillary electrophoresis was used to identify potential contributors to unmeasured anions. Results During induction of shock, pH decreased significantly from 7.41 to 7.19. The transient increase in lactate concentration from 1.5 to 5.5 mEq/L during shock was not sufficient to explain the transient increases in anion gap (+11.0 mEq/L) and strong ion gap (+7.1 mEq/L), suggesting that substantial amounts of unmeasured anions must have been generated. Capillary electrophoresis revealed increases in serum concentration of acetate (2.2 mEq/L), citrate (2.2 mEq/L), ?-ketoglutarate (35.3 ?Eq/L), fumarate (6.2 ?Eq/L), sulfate (0.1 mEq/L), and urate (55.9 ?Eq/L) after shock induction. Conclusion Large amounts of unmeasured anions were generated after hemorrhage in this highly standardized model of hemorrhagic shock. Capillary electrophoresis suggested that the hitherto unmeasured anions citrate and acetate, but not sulfate, contributed significantly to the changes in strong ion gap associated with induction of shock. PMID:18081930

  11. 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 ...

  12. Comparison of the impact of different anionic salts on the acid–base status and calcium metabolism in non-lactating, non-pregnant dairy cows

    Microsoft Academic Search

    C.-C. Gelfert; L. M. Loeffler; S. Frömer; M. Engel; K. Männer; R. Staufenbiel

    2010-01-01

    Eleven mature, non-lactating, non-pregnant, Holstein–Friesian crossbred cows were given, via a ruminal cannula, 2000mEq of one of three chloride salts, four sulfate salts, two combinations of anionic salts (AS), sodium chloride (as neutral salt), or water as control. The salts and controls were assigned in an 11×11 Latin square and the cows were randomly distributed.All of the AS induced a

  13. Molecular Anions Jack Simons

    E-print Network

    Simons, Jack

    the most recent version, click here (I found that Internet Explorer does a better job than other browsers Anions B. Selecting Specific Anions C. How Fields Are Used to Focus and Select Anions D. Problems? X. Reaction Paths XI. Summary Chapter 3. Chemically Conventional Anions I. What Makes these Anions

  14. Anions in Crystal Engineering

    SciTech Connect

    Custelcean, Radu [ORNL

    2010-01-01

    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.

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

    SciTech Connect

    Posewitz, Matthew C

    2011-06-30

    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.

  16. Quantum Chemical Approach to Estimating the Thermodynamics of Metabolic Reactions

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  17. Anion exchange membrane

    DOEpatents

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

    2013-05-07

    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.

  18. Hemolytic anemia and metabolic acidosis: think about glutathione synthetase deficiency.

    PubMed

    Ben Ameur, Salma; Aloulou, Hajer; Nasrallah, Fehmi; Kamoun, Thouraya; Kaabachi, Naziha; Hachicha, Mongia

    2015-02-01

    Glutathione synthetase deficiency (GSSD) is a rare disorder of glutathione metabolism with varying clinical severity. Patients may present with hemolytic anemia alone or together with acidosis and central nervous system impairment. Diagnosis is made by clinical presentation and detection of elevated concentrations of 5-oxoproline in urine and low glutathione synthetase activity in erythrocytes or cultured skin fibroblasts. The prognosis seems to depend on early diagnosis and treatment. We report a 4 months old Tunisian male infant who presented with severe metabolic acidosis with high anion gap and hemolytic anemia. High level of 5-oxoproline was detected in her urine and diagnosis of GSSD was made. Treatment consists of the correction of acidosis, blood transfusion, and supplementation with antioxidants. He died of severe metabolic acidosis and sepsis at the age of 15 months. PMID:25166299

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

    E-print Network

    Miraldi, Emily R. (Emily Rae)

    2012-01-01

    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-/-) ...

  20. ION CHROMATOGRAPHY OF ANIONS

    EPA Science Inventory

    A Dionex Model 10 Ion Chromatograph was evaluated for the measurement of anionic species in water. The theoretical effect of hydrogen ion activity (pH) on the elution time of phosphate and arsenate was tested and empirical selectivity coefficients were determined for the major pr...

  1. Chemiluminescence and superoxide anion production by leukocytes from chronic hemodialysis patients

    Microsoft Academic Search

    Elizabeth E Ritchey; John D Wallin; Sudhir V Shah

    1981-01-01

    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

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

    PubMed

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

    2012-09-01

    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

  3. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    Two polymer ion exchange membranes were synthesized to fulfill the needs of both electrical resistivity and anolyte/catholyte separation for utility load leveling utilizing the DOE/NASA mixed electrolyte REDOX battery. Both membranes were shown to meet mixed electrolyte utility load leveling criteria. Several modifications of an anion exchange membrane failed to meet utility load leveling REDOX battery criteria using the unmixed electrolyte REDOX cell.

  4. Gap Winds

    NSDL National Science Digital Library

    2014-09-14

    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.

  5. Gap Junctions

    PubMed Central

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2013-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

  6. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    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.

  7. Formation of interstellar anions

    NASA Astrophysics Data System (ADS)

    Senent, Maria Luisa

    2012-05-01

    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

  8. Anion-? interactions in supramolecular architectures.

    PubMed

    Chifotides, Helen T; Dunbar, Kim R

    2013-04-16

    The study of the noncovalent force between ?-acidic aromatic systems and anions, referred to as the anion-? interaction, has recently emerged as a new branch of supramolecular chemistry. The anion-? contact is complementary to the cation-? interaction, a prominent noncovalent force involved in protein structure and enzyme function. Until recently, the scientific community had overlooked the anion-? interaction due to its ostensibly counterintuitive nature. Pioneering theoretical studies in 2002, however, established that anion-? interactions are energetically favorable (~20-70 kJ/mol) and prompted a flurry of reports in support of their existence. The interest in anion-? contacts was further fueled by the importance of anions in key chemical and biological processes and the involvement of ?-rings in anion recognition and transport. Anion-? interactions hold great promise for the design of selective anion receptors, hosts or scaffolds, colorimetric sensors, and catalysts and may also affect biological functions. Currently, the area of anion-? research is highly topical in the scientific community and on a meteoric rise in the chemical literature. This Account highlights our leading findings in this burgeoning area. Our work has focused on comprehensive investigations of several unprecedented supramolecular systems, in which the anions and their close anion-? contacts are the driving elements of the final architectures. We surveyed several heterocyclic ?-acidic aromatic systems amenable to anion-? contacts and explored the subtle interplay between ligand ?-acidity, anion identity, and metal ions in mediating the ensuing self-assembled architectures. The reactions we performed between solvated first-row transition metal ions and the ?-acidic ligands bptz (3,6-bis(2-pyridyl)-1,2,4,5-tetrazine) or bmtz (3,6-bis(2-pyrimidyl)-1,2,4,5-tetrazine) resulted in unprecedented metallacycles. Our investigations revealed that the identity of the encapsulated ion dictates the metallacycle nuclearity and close anion-? contacts are critical for the metallacycle stability. Our X-ray crystallographic, NMR spectroscopic, and mass spectrometric (MS) studies demonstrated that the tetrahedral ([BF4](-), [ClO4](-)) and octahedral ([SbF6](-), [AsF6](-), [PF6](-)) anions template discrete molecular squares and pentagons, respectively. The metal ions occupy the vertices, and bptz or bmtz moieties span the edges of the metallacycles. The encapsulated anions occupy the ?-acidic cavities of the metallacycles and establish multiple close directional F/O···C(tetrazine) contacts with the edges. The observation of notable (19)F solid-state NMR chemical shifts reflects the short contacts of the encapsulated anions, findings that we corroborated by DFT calculations. The solution NMR data support the conclusion that bona fide metallacycle templation and interconversion between the metallacycles in solution occurs only in the presence of the appropriate anions. The NMR, MS, and CV data underscore the remarkable metallapentacycle stability despite the angle strain inherent in pentagons formed by octahedral metal ions. The low anion activation energies of encapsulation (?G(‡) ~ 50 kJ/mol) suggest that anion-? contacts assist the anion templation. We also studied reactions of Ag(I)X (X(-) = [PF6](-), [AsF6](-), [SbF6](-), [BF4](-)) with bptz or bppn (3,6-bis(2-pyridyl)-1,2-pyridazine) to assess the effect of the ligand ?-acidity on the preferred structures. The X-ray data revealed that the higher ?-acidity of the tetrazine ring in bptz leads to propeller-type products [Ag2(bptz)3](2+) exhibiting prominent short anion-? contacts. By contrast, the less ?-acidic bppn preferentially favors grids [Ag4(bppn)4](4+) which exhibit maximized ?-? interactions. Finally, we explored the reactions of the extended ?-acidic heterocycle HAT(CN)6 (1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile) with the Cl(-), Br(-), I(-) ions which lead to highly colored solutions/crystals. X-ray crystallographic studies of the HAT(CN)6/halide complexes revealed

  9. Dynamic chemistry of anion recognition

    SciTech Connect

    Custelcean, Radu [ORNL

    2012-01-01

    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.

  10. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  11. Pseudorotation in fullerene anions

    NASA Astrophysics Data System (ADS)

    Dunn, Janette L.; Hands, Ian D.; Bates, Colin A.

    2007-07-01

    Jahn-Teller (JT) problems are often characterised by an adiabatic potential energy surface (APES) containing either a set of isoenergetic wells or a trough of equivalent-energy points, which may be warped by higher-order coupling terms or anisotropic effects. In all three cases, the JT effect will be dynamic. Either tunnelling between the wells or rotation (of a distortion) around the trough will restore the original symmetry of the system. This motion is referred to as pseudorotation. It should be possible to observe a JT system in a distorted geometry if measurements are made on a sufficiently short timescale. In various cubic systems, this timescale has been calculated to be the order of picoseconds. Such timescales are accessible using modern methods of ultrafast spectroscopy. Measurements of pseudorotation rates can lead to important information on the strength and nature of the JT coupling present. We will present analytical calculations that allow the rate of pseudorotation to be determined in terms of the vibronic coupling parameters. We will show how these results can be applied to E ? e systems and then to the more complicated system applicable to C60- anions. This is of particular interest because of the high icosahedral symmetry of fullerene ions and also because of the many potential uses of materials containing these ions. We conclude by outlining experiments that should be capable of measuring pseudorotation in C 60 anions.

  12. Voltage-dependent anion channel (VDAC) as mitochondrial governator—Thinking outside the box

    Microsoft Academic Search

    John J. Lemasters; Ekhson Holmuhamedov

    2006-01-01

    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)

  13. Cation disorder and anion displacement in DIIXVI - AIBIIIXVI2 semiconductors

    NASA Astrophysics Data System (ADS)

    Schorr, S.; Wagner, G.; Tovar, M.; Sheptyakov, D.

    2006-09-01

    The composition dependent structural phase transitions (tetragonal-cubic) in (ZnX)2x(CuBX2)1-x alloys (B = Ga, In; X = S, Se, Te) were studied by neutron and X-ray powder diffraction as well as TEM. The transitions are due to the interplay of disorder within the cation substructure and the displacement of the anions. It goes along with a phase separation by cation ordering, i. e. there is a miscibility gap (2-phase field), where tetragonal domains and a cubic matrix coexist. Within a homologous series its extension and the particular composition of end members of this 2-phase field depend on the size of the anion. However, for the same anion its width is determined by the BIII cation. For the tetragonal single phase a non-random Zn distribution on the cation sites of the chalcopyrite-type structure was revealed, indicating the tendency of disorder in the cation substructure.

  14. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

    Alexander, S.; Hodgdon, R. B.

    1977-01-01

    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.

  15. Organic Anion Transporting Polypeptides

    PubMed Central

    Stieger, Bruno; Hagenbuch, Bruno

    2013-01-01

    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

  16. Capillary electrophoresis of inorganic anions.

    PubMed

    Kaniansky, D; Masár, M; Marák, J; Bodor, R

    1999-02-26

    This review deals with the separation mechanisms applied to the separation of inorganic anions by capillary electrophoresis (CE) techniques. It covers various CE techniques that are suitable for the separation and/or determination of inorganic anions in various matrices, including capillary zone electrophoresis, micellar electrokinetic chromatography, electrochromatography and capillary isotachophoresis. Detection and sample preparation techniques used in CE separations are also reviewed. An extensive part of this review deals with applications of CE techniques in various fields (environmental, food and plant materials, biological and biomedical, technical materials and industrial processes). Attention is paid to speciations of anions of arsenic, selenium, chromium, phosphorus, sulfur and halogen elements by CE. PMID:10189691

  17. [Complex metabolic disorders revealing a gastric ulcer of the bulb. A case report].

    PubMed

    Neffati, F; Hellara, I; Jelizi, M A; Bahri, J; Douki, W; Amor, A Ben; Najjar, M F

    2009-01-01

    We report the case of a 54-year-old man, without particular pathological antecedents admitted to the emergency of the university hospital of Monastir, for right renal colic. Radiography of the urinary tract without preparation and renal echography showed bilateral renal lithiasis and a right ureteral lithiasis. The interrogation revealed concept of vomiting after which the patient felt relieved. The biological assessment objectified an hypochloremic metabolic alcalosis, an increase in the anion gap, a severe impaired renal function of obstructive origin and an hypokaliemia. The presence of the lithiasis did not explain on its own the metabolic disorders of this patient. The other investigations showed that initial pathology was an evolutionary bulb ulcer into pre-stenosis justifying treatment by omeprazole and explaining the biological disorders. PMID:19654086

  18. Clinical utility of standard base excess in the diagnosis and interpretation of metabolic acidosis in critically ill patients.

    PubMed

    Park, M; Taniguchi, L U; Noritomi, D T; Libório, A B; Braga, A L; Maciel, A T; Cruz-Neto, L M

    2008-03-01

    The aims of this study were to determine whether standard base excess (SBE) is a useful diagnostic tool for metabolic acidosis, whether metabolic acidosis is clinically relevant in daily evaluation of critically ill patients, and to identify the most robust acid-base determinants of SBE. Thirty-one critically ill patients were enrolled. Arterial blood samples were drawn at admission and 24 h later. SBE, as calculated by Van Slyke's (SBE VS) or Wooten's (SBE W) equations, accurately diagnosed metabolic acidosis (AUC = 0.867, 95%CI = 0.690-1.043 and AUC = 0.817, 95%CI = 0.634-0.999, respectively). SBE VS was weakly correlated with total SOFA (r = -0.454, P < 0.001) and was similar to SBE W (r = -0.482, P < 0.001). All acid-base variables were categorized as SBE VS <-2 mEq/L or SBE VS <-5 mEq/L. SBE VS <-2 mEq/L was better able to identify strong ion gap acidosis than SBE VS <-5 mEq/L; there were no significant differences regarding other variables. To demonstrate unmeasured anions, anion gap (AG) corrected for albumin (AG A) was superior to AG corrected for albumin and phosphate (AG A+P) when strong ion gap was used as the standard method. Mathematical modeling showed that albumin level, apparent strong ion difference, AG A, and lactate concentration explained SBE VS variations with an R(2) = 0.954. SBE VS with a cut-off value of <-2 mEq/L was the best tool to diagnose clinically relevant metabolic acidosis. To analyze the components of SBE VS shifts at the bedside, AG A, apparent strong ion difference, albumin level, and lactate concentration are easily measurable variables that best represent the partitioning of acid-base derangements. PMID:18097497

  19. Association of two single-isomer anionic CD in NACE for the chiral and achiral separation of fenbendazole, its sulphoxide and sulphone metabolites: application to their determination after in vitro metabolism.

    PubMed

    Rousseau, Anne; Gillotin, Florian; Chiap, Patrice; Crommen, Jacques; Fillet, Marianne; Servais, Anne-Catherine

    2010-05-01

    A NACE method was developed for the separation of fenbendazole (FBZ), a prochiral drug giving rise to chiral (oxfendazole or OFZ) and nonchiral (FBZ sulphone or FBZSO(2)) metabolites. First, the effect of the nature and the concentration of CD as well as that of the acidic BGE on the enantiomeric separation of OFZ were studied. OFZ enantiomers were completely resolved using a BGE made up of 10 mM ammonium formate and 0.5 M TFA in methanol containing 10 mM heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-CD and 10 mM heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-CD. Moreover, the NACE method was found to be particularly well suited to the simultaneous determination of FBZ, OFZ enantiomers, and FBZSO(2). Thiabendazole was selected as an internal standard. The CD-NACE potential was then evaluated for in vitro metabolism studies using FBZ as a model case. The OFZ enantiomers and FBZSO(2) could be detected after incubation of FBZ in the phenobarbital-induced male rat liver microsomes systems. PMID:20376816

  20. Hydrogen in anion vacancies of semiconductors

    SciTech Connect

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

    2009-01-01

    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.

  1. Hydrogen in anion vacancies of semiconductors

    NASA Astrophysics Data System (ADS)

    Du, Mao-Hua; Singh, David J.

    2009-05-01

    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.

  2. Anion exchange polymer electrolytes

    DOEpatents

    Kim, Yu Seung; Kim, Dae Sik; Lee, Kwan-Soo

    2013-07-23

    Solid anion exchange polymer electrolytes and compositions comprising chemical compounds comprising a polymeric core, a spacer A, and a guanidine base, wherein said chemical compound is uniformly dispersed in a suitable solvent and has the structure: ##STR00001## wherein: i) A is a spacer having the structure O, S, SO.sub.2, --NH--, --N(CH.sub.2).sub.n, wherein n=1-10, --(CH.sub.2).sub.n--CH.sub.3--, wherein n=1-10, SO.sub.2-Ph, CO-Ph, ##STR00002## wherein R.sub.5, R.sub.6, R.sub.7 and R.sub.8 each are independently --H, --NH.sub.2, F, Cl, Br, CN, or a C.sub.1-C.sub.6 alkyl group, or any combination of thereof; ii) R.sub.9, R.sub.10, R.sub.11, R.sub.12, or R.sub.13 each independently are --H, --CH.sub.3, --NH.sub.2, --NO, --CH.sub.nCH.sub.3 where n=1-6, HC.dbd.O--, NH.sub.2C.dbd.O--, --CH.sub.nCOOH where n=1-6, --(CH.sub.2).sub.n--C(NH.sub.2)--COOH where n=1-6, --CH--(COOH)--CH.sub.2--COOH, --CH.sub.2--CH(O--CH.sub.2CH.sub.3).sub.2, --(C.dbd.S)--NH.sub.2, --(C.dbd.NH)--N--(CH.sub.2).sub.nCH.sub.3, where n=0-6, --NH--(C.dbd.S)--SH, --CH.sub.2--(C.dbd.O)--O--C(CH.sub.3).sub.3, --O--(CH.sub.2).sub.n--CH--(NH.sub.2)--COOH, where n=1-6, --(CH.sub.2).sub.n--CH.dbd.CH wherein n=1-6, --(CH.sub.2).sub.n--CH--CN wherein n=1-6, an aromatic group such as a phenyl, benzyl, phenoxy, methylbenzyl, nitrogen-substituted benzyl or phenyl groups, a halide, or halide-substituted methyl groups; and iii) wherein the composition is suitable for use in a membrane electrode assembly.

  3. Differential Diagnosis of Nongap Metabolic Acidosis: Value of a Systematic Approach

    PubMed Central

    Madias, Nicolaos E.

    2012-01-01

    Summary Nongap metabolic acidosis is a common form of both acute and chronic metabolic acidosis. Because derangements in renal acid-base regulation are a common cause of nongap metabolic acidosis, studies to evaluate renal acidification often serve as the mainstay of differential diagnosis. However, in many cases, information obtained from the history and physical examination, evaluation of the electrolyte pattern (to determine if a nongap acidosis alone or a combined nongap and high anion gap metabolic acidosis is present), and examination of the serum potassium concentration (to characterize the disorder as hyperkalemic or hypokalemic in nature) is sufficient to make a presumptive diagnosis without more sophisticated studies. If this information proves insufficient, indirect estimates or direct measurement of urinary NH4+ concentration, measurement of urine pH, and assessment of urinary HCO3? excretion can help in establishing the diagnosis. This review summarizes current information concerning the pathophysiology of this electrolyte pattern and the value and limitations of all of the diagnostic studies available. It also provides a systematic and cost-effective approach to the differential diagnosis of nongap metabolic acidosis. PMID:22403272

  4. Metabolic Syndrome

    MedlinePLUS

    ... page from the NHLBI on Twitter. What Is Metabolic Syndrome? Metabolic (met-ah-BOL-ik) syndrome is the ... three metabolic risk factors to be diagnosed with metabolic syndrome. A large waistline. This also is called abdominal ...

  5. Synthesis of Cationic Extended Frameworks for Anion-Based Applications

    E-print Network

    Fei, Honghan

    2012-01-01

    solvent- mediated anion exchange with a possible exfoliation and recrystallizationsolvent-mediated process anion exchange process involving dissolution of metal, ligand and anion and competitive recrystallization

  6. Ion exchange polymers for anion separations

    DOEpatents

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

    1997-01-01

    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.

  7. Ion exchange polymers for anion separations

    DOEpatents

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

    1997-09-23

    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.

  8. A REVIEW ON ACID BASE STATUS IN DAIRY COWS: IMPLICATIONS OF DIETARY CATION-ANION BALANCE

    Microsoft Academic Search

    D. Afzaal; M. Nisa; M. A. Khan; M. Sarwar

    2004-01-01

    The acid base status of a dairy cow is maintained within a narrow range. The key mechanisms involving blood, cells and lungs, perform this function. Although other minerals have an impact on acid base metabolism, the minerals used in dietary cation-anion balance (DCAB) namely sodium (Na), potassium (K) and chloride (Cl) have the greatest effect. Hence, acid base status implicates

  9. Polymerization of anionic wormlike micelles.

    PubMed

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

    2006-01-31

    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

  10. Aza compounds as anion receptors

    DOEpatents

    Lee, H.S.; Yang, X.Q.; McBreen, J.

    1998-01-06

    A family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of Li{sup +} ion in alkali metal batteries. 3 figs.

  11. Aza compounds as anion receptors

    SciTech Connect

    Lee, Hung Sui (East Setauket, NY); Yang, Xiao-Qing (Port Jefferson Station, NY); McBreen, James (Bellport, NY)

    1998-01-06

    A family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of Li.sup.+ ion in alkali metal batteries.

  12. Anion composition of aça?? extracts.

    PubMed

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

    2013-06-26

    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

  13. Inception report and Gap analysis

    E-print Network

    Inception report and Gap analysis Boiler inspection Riga, June 2004 #12;Inception report and gap............................................................................... 4 2.1 INSTITUTIONAL GAPS........................................................................................................................ 4 2.3 TECHNICAL GAP

  14. Metabolic neuropathies

    MedlinePLUS

    Neuropathy - metabolic ... can be caused by many different things. Metabolic neuropathy may be caused by: A problem with the ... one of the most common causes of metabolic neuropathies. People who are at the highest risk of ...

  15. Analysis of anions in beer using ion chromatography

    PubMed Central

    Bruce, Jonathan

    2002-01-01

    The majority of anions found in beer are a consequence of impurities derived from the water used during the brewing process. The process of beer manufacture consists of malting, brewing and fermentation followed by maturation before filtration and finally storage. Strict quality control is required because the presence of certain anions outside strictly defined tolerance limits can affect the flavour characteristics of the finished product. The anions present were quantified using the technique of ion chromatography with the Metrohm modular system following sample preparation. The analysis produced a result of the order 200 mg l-1 for chloride, phosphate and sulphate and around 20 mg l-1 for nitrate. If the chloride level exceeds 250 mg l-1, then the sweetness of the beer is enhanced, but yeast flocculation can be hindered. An excess of sulphate can give a sharp, dry edge to hopped beers and excessive amounts of nitrate have been found to harm the yeast metabolism after conversion to the nitrite form. As water is a primary ingredient within beer, its quality and type is a fundamental factor in establishing many of the distinctive regional beers that can be found in the United Kingdom and is thus monitored carefully. PMID:18924733

  16. Propranolol hydrochloride–anionic polymer binding interaction

    Microsoft Academic Search

    Sevgi Takka

    2003-01-01

    Three different anionic polymers namely Eudragit S 100, Eudragit L 100-55 (methacrylic acid copolymers), and sodium carboxymethylcellulose (NaCMC) were used to evaluate the propranolol hydrochloride–anionic polymer interaction. The physical and chemical properties of propranolol hydrochloride and anionic polymer complex were investigated using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The DSC profiles demonstrated that the characteristic peak

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

    SciTech Connect

    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

    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.

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

    PubMed

    Sweet, Douglas H

    2005-05-01

    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. PMID:15845414

  19. The prototype GAPS (pGAPS) experiment

    NASA Astrophysics Data System (ADS)

    Mognet, S. A. I.; Aramaki, T.; Bando, N.; Boggs, S. E.; von Doetinchem, P.; Fuke, H.; Gahbauer, F. H.; Hailey, C. J.; Koglin, J. E.; Madden, N.; Mori, K.; Okazaki, S.; Ong, R. A.; Perez, K. M.; Tajiri, G.; Yoshida, T.; Zweerink, J.

    2014-01-01

    The General Antiparticle Spectrometer (GAPS) experiment is a novel approach for the detection of cosmic ray antiparticles. A prototype GAPS (pGAPS) experiment was successfully flown on a high-altitude balloon in June of 2012. The goals of the pGAPS experiment were: to test the operation of lithium drifted silicon (Si(Li)) detectors at balloon altitudes, to validate the thermal model and cooling concept needed for engineering of a full-size GAPS instrument, and to characterize cosmic ray and X-ray backgrounds. The instrument was launched from the Japan Aerospace Exploration Agency's (JAXA) Taiki Aerospace Research Field in Hokkaido, Japan. The flight lasted a total of 6 h, with over 3 h at float altitude (~33 km). Over one million cosmic ray triggers were recorded and all flight goals were met or exceeded.

  20. Sweet anion receptors: recognition of chiral carboxylate anions by D-glucuronic-acid-decorated diindolylmethane.

    PubMed

    Granda, Jaros?aw M; Jurczak, Janusz

    2013-09-20

    Anion receptors containing glucuronic acid were synthesized, and their anion binding ability studied. Chirality of anionic guests derived from mandelic acid and amino acids can be distinguished not only in terms of stability constants but also by significant differences in chemical shift changes for sugar moiety protons. PMID:23988260

  1. USGS Gap Analysis Program

    NSDL National Science Digital Library

    This site provides the latest information on the Gap Analysis Program (GAP). The central goal of the GAP Program is to collect and integrate many levels of biological, physical, and policy information on a large scale, in order to identify gaps in current resource management plans. It is maintained by the USGS Biological Resources Division with the mission of "providing regional assessments of the conservation status of native vertebrate species and natural land cover types and to facilitate the application of this information to land management activities." This site is divided into eight sections: overview, the gap analysis handbook, state project information, gap reports/publications, a bulletin board, aquatic gap, nature mapping (an educational tool), and links to related sites. New press releases and conference poster contents are featured at the top of the site. Users can access state and regional GAP information or use the search engine to find other topics of interest.

  2. NATIONAL GAP ANALYSIS PROGRAM

    EPA Science Inventory

    GAP Analysis is a rapid conservation evaluation method for assessing the current status of biodiversity at large spatial scales. GAP Analysis provides a systematic approach for evaluating the protection afforded biodiversity in given areas. It uses Geographic Information System (...

  3. New Advances in Fluorogenic Anion Chemosensors

    Microsoft Academic Search

    Ramón Martínez-Máñez; Félix Sancenón

    2005-01-01

    The development of anion chemosensors is an area of recent interest. We make here a comprehensive review of new advances on anion chemosensing, reported in the literature during the year 2004. The review follows a classification of the sensing systems based on design principles. It comprises: the binding site-signalling subunit approach, the displacement approach and the use of fluoro-chemodosimeters. The

  4. Tripodal Receptors for Cation and Anion Sensors

    PubMed Central

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

    2006-01-01

    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.

  5. Gels based on anion recognition between triurea receptor and phosphate anion.

    PubMed

    Yang, Cuiling; Wu, Biao; Chen, Yongming; Zhang, Ke

    2015-04-01

    Anion recognition between the triurea receptor and phosphate anion is demonstrated as the cross-linkage to build supramolecular polymer gels for the first time. A novel multi-block copolymer (3) is designed to have functional triurea groups as cross-linking units along the polymer main chain. By virtue of anion coordination between the triurea receptor and phosphate anion with a binding mode of 2:1, supramolecular polymer gels are then prepared based on anion recognition using 3 as the building block. PMID:25694389

  6. Covalent Polymers Containing Discrete Heterocyclic Anion Receptors

    PubMed Central

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

    2010-01-01

    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

  7. Funding Gap Study.

    ERIC Educational Resources Information Center

    Newmyer, Joe; McIntyre, Chuck

    The "funding gap" in public higher education in California represents the difference between state appropriations and the amount needed to fully support each segment's educational mission. This report identifies and defines the funding gap for the California Community Colleges (CCC); measures the consequences of this gap on program quality and…

  8. Triggered vacuum gaps

    Microsoft Academic Search

    J. M. Lafferty

    1966-01-01

    Characteristics of a sealed vacuum gap are described and the difficulties encountered in applying this gap as an overvoltage protection device are discussed. It is shown how these difficulties can be ameliorated by the use of gas-free electrode materials and by triggering the gap when breakdown is required. Several methods of triggering are discussed and some practical triggering devices are

  9. Behind the Pay Gap

    ERIC Educational Resources Information Center

    Dey, Judy Goldberg; Hill, Catherine

    2007-01-01

    Women have made remarkable gains in education during the past three decades, yet these achievements have resulted in only modest improvements in pay equity. The gender pay gap has become a fixture of the U.S. workplace and is so ubiquitous that many simply view it as normal. "Behind the Pay Gap" examines the gender pay gap for college graduates.…

  10. Metabolic Syndrome

    MedlinePLUS

    ... you know? One in five Americans has the metabolic syndrome. WhO is At risk fOr the metAbOlic syndrOme? The syndrome runs in families and is more ... High blood pressure Most people who have the metabolic syndrome feel healthy and may not have any signs ...

  11. Postischemic generation of superoxide anion by newborn pig brain.

    PubMed

    Armstead, W M; Mirro, R; Busija, D W; Leffler, C W

    1988-08-01

    Cerebral superoxide anion generation during reperfusion after total cerebral ischemia was measured in newborn pigs. Superoxide dismutase (SOD)-inhibitable nitroblue tetrazolium (NBT) reduction was determined using two closed cranial windows inserted over the parietal cortices. Twenty minutes of total cerebral ischemia was produced by increasing intracranial pressure, and SOD-inhibitable NBT reduction was determined during 20 min of reperfusion. SOD-inhibitable NBT reduction (8.7 +/- 1.5 pmol.mm-2.20 min-1) was greater in piglets subjected to cerebral ischemia followed by reperfusion than in control piglets not exposed to ischemia (1.6 +/- 1.3 pmol.mm-2.20 min-1). Pretreatment with indomethacin (5 mg/kg iv) markedly reduced postischemia SOD-inhibitable NBT reduction (2.8 +/- 1.1 pmol.mm-2.20 min-1). We conclude that superoxide anion radical is produced by newborn pig brain during postischemic reperfusion. Furthermore, cyclooxygenase metabolism of arachidonic acid appears to be a major source of this activated oxygen during reperfusion of ischemic piglet brain. PMID:2841877

  12. GapZappers

    NSDL National Science Digital Library

    Colleen King

    2013-01-01

    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.

  13. Anion Cluster: Assembly of Dihydrogen Phosphates for the Formation of a Cyclic Anion Octamer.

    PubMed

    Hossain, Md Alamgir; I??klan, Muhammet; Pramanik, Avijit; Saeed, Musabbir A; Fronczek, Frank R

    2012-02-01

    Structural characterization of a dihydrogen phosphate complex of triprotonated tris[2-(2-thienylmethylamino)ethyl] amine shows that eight dihydrogen phosphate anions are assembled around the host by strong interactions of H-bond donors and acceptors to form a new type of cyclic anion octamer as (H(2)PO(4) (-))(8), an analogy of cyclic water octamer. The presence of an anion cluster has also been identified by electrospray ionization mass spectrometry and (31)P NMR experiments. PMID:22435043

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  15. Rapidity Gaps Between Jets

    E-print Network

    J. M. Butterworth; M. E. Hayes; M. H. Seymour; L. E. Sinclair

    1996-09-02

    An excess of events with a rapidity gap between jets, over what would be expected from non-diffractive processes, has been observed at HERA. A process based on a perturbative QCD calculation of colour singlet exchange has been added to HERWIG. With this addition, HERWIG is able to describe the number of events with a gap between jets over the number without a gap. This gap fraction is predicted to rise at large rapidity intervals between jets which would only be visible if the detector coverage were increased.

  16. 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...

  17. Metabolic myopathies

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  18. GAP ACTIVITY TRACKING MATRIX

    EPA Science Inventory

    Resource Purpose: The information collected serves the following purposes: (1) provides a summary of funds allocated by tribe for the GAP Program, (2) provides an overview in the types of activities the tribes are engaged in with GAP funds, and (3) allows OW to document the...

  19. Which Achievement Gap?

    ERIC Educational Resources Information Center

    Anderson, Sharon; Medrich, Elliott; Fowler, Donna

    2007-01-01

    From the halls of Congress to the local elementary school, conversations on education reform have tossed around the term "achievement gap" as though people all know precisely what that means. As it's commonly used, "achievement gap" refers to the differences in scores on state or national achievement tests between various student demographic…

  20. Confronting the Achievement Gap

    ERIC Educational Resources Information Center

    Gardner, David

    2007-01-01

    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…

  1. The Gender Pay Gap

    Microsoft Academic Search

    Francine D. Blau

    1996-01-01

    Empirical research on gender pay gaps has traditionally focused on the role of gender-specific factors, particularly gender differences in qualifications and differences in the treatment of otherwise equally qualified male and female workers (i.e., labor market discrimination). This paper explores the determinants of the gender pay gap and argues for the importance of an additional factor, wage structure, the array

  2. Senseless Extravagance, Shocking Gaps

    ERIC Educational Resources Information Center

    Weissbourd, Richard; Dodge, Trevor

    2012-01-01

    Although most people in the United States believe, at least theoretically, in educational equality, fewer and fewer appear to care about the resource gaps between affluent and poor schools, says Weissbourd. He illustrates these gaps with vivid descriptions of what he calls an "opulence arms race" among affluent independent schools, but points out…

  3. Advanced rapidity gap trigger

    E-print Network

    V. A. Abramovsky; A. V. Dmitriev

    2005-01-07

    Nubmer of physically 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.

  4. Metabolic ecology.

    PubMed

    Humphries, Murray M; McCann, Kevin S

    2014-01-01

    Ecological theory that is grounded in metabolic currencies and constraints offers the potential to link ecological outcomes to biophysical processes across multiple scales of organization. The metabolic theory of ecology (MTE) has emphasized the potential for metabolism to serve as a unified theory of ecology, while focusing primarily on the size and temperature dependence of whole-organism metabolic rates. Generalizing metabolic ecology requires extending beyond prediction and application of standardized metabolic rates to theory focused on how energy moves through ecological systems. A bibliometric and network analysis of recent metabolic ecology literature reveals a research network characterized by major clusters focused on MTE, foraging theory, bioenergetics, trophic status, and generalized patterns and predictions. This generalized research network, which we refer to as metabolic ecology, can be considered to include the scaling, temperature and stoichiometric models forming the core of MTE, as well as bioenergetic equations, foraging theory, life-history allocation models, consumer-resource equations, food web theory and energy-based macroecology models that are frequently employed in ecological literature. We conclude with six points we believe to be important to the advancement and integration of metabolic ecology, including nomination of a second fundamental equation, complementary to the first fundamental equation offered by the MTE. PMID:24028511

  5. Studies of anions sorption on natural zeolites.

    PubMed

    Barczyk, K; Mozgawa, W; Król, M

    2014-12-10

    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

  6. 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...

  7. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    SciTech Connect

    Bowman-James, Kristen

    2004-12-01

    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.

  8. Strong anion determination in biological fluids by capillary electrophoresis for clinical diagnostics.

    PubMed

    de Macedo, Adriana Nori; Jiwa, Muhammad Irfan Yasin; Macri, Joseph; Belostotsky, Vladimir; Hill, Stephen; Britz-McKibbin, Philip

    2013-11-19

    New methods for quantitative analysis of strong anions are required for diagnostic testing of human diseases. Current techniques suffer from poor selectivity and/or long analysis times that are not amenable for labile anions in high-saline or volume-restricted samples. We introduce a rapid assay (<5 min) based on capillary electrophoresis (CE) with indirect UV detection for simultaneous analysis of sulfate, sulfite, and chloride in human urine, plasma, and sweat specimens. Remarkable selectivity for strong anions is achieved by using an acidic background electrolyte under reversed polarity that results in electrokinetic rejection of matrix interferences at the capillary inlet. A dual co-ion probe system consisting of 5 mM naphthalene disulfonate (NDS) and 5 mM naphthalene trisulfonate (NTS) in 0.4 M formic acid, pH 2.0 is developed for detection of UV transparent anions (S/N ? 3, 60 ?M with a 25 ?m inner diameter fused-silica capillary) with good peak symmetry and baseline stability. Due to the chemical reactivity of sulfite, dilute formaldehyde is used as a reagent to form an acid-stable hydroxymethylsulfonate adduct. Method validation confirmed excellent linearity (R(2) > 0.999), good accuracy (mean bias ?7%), and acceptable long-term reproducibility (CV < 10%) over 20 days. The assay allows for artifact-free determination of sulfate and sulfite with consistent results for chloride when compared to standard electrochemical methods (R(2) > 0.975). Preliminary data suggest that kidney-stone formers have lower urinary sulfate excretion relative to non-kidney-stone patient controls (p = 0.0261). CE offers a selective yet robust platform for routine analysis of strong anions that is needed for confirmatory testing of cystic fibrosis, sulfite oxidase deficiency, urolithiasis, and other disorders of sulfur metabolism and/or anion transport. PMID:24127785

  9. Circulating Glycated Albumin and Glomerular Anionic Charges

    PubMed Central

    Londoño, I.; Gingras, D.

    2003-01-01

    Aiming to discern the mechanisms by which circulating glycated albumin alters the glomerular filtration properties that lead to glomerular dysfunction in diabetes, the authors studied the distribution and densities of anionic charges through the rat glomerular wall upon intravascular infusion of Amadori products, as well as in various conditions of increased glomerular permselectivity. Polylysine-gold was used as the probe to reveal the anionic charges. The study was carried on renal tissue sections of bovine serum albumin (BSA)- and glycated BSA–injected, normoglycemic animals. Results were generated through morphometrical evaluations of the gold labeling. Changes in glomerular anionic distribution were corroborated on renal tissue sections of short- and long-term diabetic rats and of normal newborn rats, situations known for abnormal glomerular filtration. Altered renal function in these conditions was clearly associated with changes in glomerular anionic charges. On the other hand, the infusion of glycated albumin in the circulation of normal rats, though altering glomerular filtration properties, did not modify the distribution and density of the polylysine-gold labeling through the glomerular basement membrane. Thus, anionic charges seem not to be the factor involved in the early changes of glomerular permeability induced by circulating glycated albumin. PMID:14630570

  10. Further studies on the clinical features and clinicopathological findings of a syndrome of metabolic acidosis with minimal dehydration in neonatal calves.

    PubMed Central

    Kasari, T R; Naylor, J M

    1986-01-01

    A syndrome of metabolic acidosis of unknown etiology was diagnosed in twelve beef calves 7 to 31 days old. Principal clinical signs were unconsciousness or depression concomitant with weakness and ataxia. Other signs included weak or absent suckle and menace reflexes, succussable nontympanic fluid sounds in the anterior abdomen, and a slow, deep thoracic and abdominal pattern of respiration. The variation in clinical signs between calves was highly correlated (r = 0.87, P less than 0.001) with their acid-base (base deficit) status. Abnormal laboratory findings included reduced venous blood pH, pCO2 and bicarbonate ion concentration as well as hyperchloremia, elevated blood urea nitrogen, increased anion gap and neutrophilic leukocytosis with a left shift. Sodium bicarbonate solution administered intravenously effectively raised blood pH and improved demeanor, ambulation and appetite. All calves did well following a return to a normal acid-base status. PMID:3024795

  11. An anionic surfactant for EOR applications

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  12. Fiber optic gap gauge

    DOEpatents

    Wood, Billy E. (Livermore, CA); Groves, Scott E. (Brentwood, CA); Larsen, Greg J. (Brentwood, CA); Sanchez, Roberto J. (Pleasanton, CA)

    2006-11-14

    A lightweight, small size, high sensitivity gauge for indirectly measuring displacement or absolute gap width by measuring axial strain in an orthogonal direction to the displacement/gap width. The gap gauge includes a preferably titanium base having a central tension bar with springs connecting opposite ends of the tension bar to a pair of end connector bars, and an elongated bow spring connected to the end connector bars with a middle section bowed away from the base to define a gap. The bow spring is capable of producing an axial strain in the base proportional to a displacement of the middle section in a direction orthogonal to the base. And a strain sensor, such as a Fabry-Perot interferometer strain sensor, is connected to measure the axial strain in the base, so that the displacement of the middle section may be indirectly determined from the measurement of the axial strain in the base.

  13. Generation gaps in engineering?

    E-print Network

    Kim, David J. (David Jinwoo)

    2008-01-01

    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. ...

  14. 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...

  15. Causes of metabolic acidosis in canine hemorrhagic shock: role of unmeasured ions

    Microsoft Academic Search

    Dirk Bruegger; Gregor I Kemming; Matthias Jacob; Franz G Meisner; Christoph J Wojtczyk; Kristian B Packert; Peter E Keipert; N Simon Faithfull; Oliver P Habler; Bernhard F Becker; Markus Rehm

    2007-01-01

    INTRODUCTION: Metabolic acidosis during hemorrhagic shock is common and conventionally considered to be due to hyperlactatemia. There is increasing awareness, however, that other nonlactate, unmeasured anions contribute to this type of acidosis. METHODS: Eleven anesthetized dogs were hemorrhaged to a mean arterial pressure of 45 mm Hg and were kept at this level until a metabolic oxygen debt of 120

  16. Rapidity Gaps Between Jets

    Microsoft Academic Search

    J. M. Butterworth; M. E. Hayes; M. H. Seymour; L. E. Sinclair

    1996-01-01

    An excess of events with a rapidity gap between jets, over what would be\\u000aexpected from non-diffractive processes, has been observed at HERA. A process\\u000abased on a perturbative QCD calculation of colour singlet exchange has been\\u000aadded to HERWIG. With this addition, HERWIG is able to describe the number of\\u000aevents with a gap between jets over the number

  17. There Are GAPS and There Are GAPS

    NSDL National Science Digital Library

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

    1997-01-03

    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.

  18. Electrophoretic separation of inorganic anions with an anion complexone-modified capillary column

    Microsoft Academic Search

    Chuen-Ying Liu; Wei-Hsi Chen

    1998-01-01

    A twenty-eight-membered macrocyclic polyamine, 4,8,12,18,22,26-hexaaza-1,15-dioxacyclooctaeicosane ([28]ane-N6O2), was covalently bound to fused-silica for the electrophoretic separation of simple anions, complex anions and metal-containing anions. Parameters influencing bound ligand complexation properties or the electrophoretic behavior of analytes, such as the nature of the background electrolyte, the pH and concentration were investigated. The separation of metallocyanide complexes, Fe(CN)63? and Fe(CN)64? has been achieved.

  19. Solvent-dependent enthalpic versus entropic anion binding by biaryl substituted quinoline based anion receptors.

    PubMed

    Sun, Zhan-Hu; Albrecht, Markus; Raabe, Gerhard; Pan, Fang-Fang; Räuber, Christoph

    2015-01-01

    Anion receptors based on an 8-thiourea substituted quinoline with pentafluorinated (1a) or nonfluorinated (1b) biarylamide groups in the 2-position show similar binding of halide anions with somewhat higher association constants for the more acidic fluorinated derivative. Surprisingly, binding affinities for the halides in the case of the nonfluorinated 1b are similar in nonpolar chloroform or polar DMSO as solvent. Thorough thermodynamic investigations based on NMR van't Hoff analysis show that anion binding in chloroform is mainly enthalpically driven. In DMSO, entropy is the driving force for the binding of the ions with replacement of attached solvent. PMID:25516141

  20. Metabolism Roundup

    NSDL National Science Digital Library

    Science Update (AAAS; )

    2008-02-29

    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.

  1. Metabolic Myopathies

    MedlinePLUS

    ... that affect the body’s muscles. [Metabolism refers to chemical reactions that provide energy and nutrients, or substances necessary ... made in cells from sugars or fats by chemical reactions called pathways. Normally, most ATP is produced in ...

  2. Metabolic Engineering

    Microsoft Academic Search

    R. Michael Raab; Keith Tyo; Gregory Stephanopoulos

    Metabolic engineering is a powerful methodology aimed at intelligently designing new biological\\u000a pathways, systems, and ultimately phenotypes through the use of recombinant DNA technology. Built\\u000a largely on the theoretical and computational analysis of chemical systems, the field has evolved to\\u000a incorporate a growing number of genome scale experimental tools. This combination of rigorous\\u000a analysis and quantitative molecular biology methods has endowed metabolic

  3. Metabolic Engineering

    Microsoft Academic Search

    Lars M. Voll; Frederik Börnke

    \\u000a \\u000a The metabolic engineering of primary metabolism provides an enormous potential to improve the value of plant-based raw materials\\u000a for food and industrial applications. This chapter focuses on the current progress in the manipulation of carbohydrate and\\u000a lipid biosynthesis in transgenic starch and oilseed crops, respectively. In most approaches, the manipulation of the biosynthetic\\u000a routes revealed limitations and bottlenecks in the

  4. ANIONIC EFFECTS IN HOT SURFACE COMBUSTIONS

    Microsoft Academic Search

    William Bannister; Alfred Donatelli; Francis Bonner; Fang Lai; Pradeep Kurup; James Egan; Edwin Jahngen; Shih-Kun Chiang; Sandip Sengupta; Ramaswamy Nagarajan; Nukul Euaphantasate; Virinder Parma; Mario Cazeca; Eric Chen; Antonio Morales

    Hot surface oxidations are commonly thought to involve initial free radical hydrogen atom abstraction. Our evidence implicates initial Lewis base deprotonation by O•- atomic oxygen radical anions to form negatively charged carbanions. Subsequent rate determining electron transfers generate free radicals which only then give rise to combustion. Correlations regarding ignition temperatures and hydrocarbon oxidation product identity are consistent with carbanionic

  5. Photoelectron spectroscopic studies of 5-halouracil anions

    SciTech Connect

    Radisic, Dunja; Ko, Yeon Jae; Nilles, John M.; Stokes, Sarah T.; Bowen, Kit H. [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Sevilla, Michael D. [Department of Chemistry, Oakland University, Rochester, Michigan 48309 (United States); Rak, Janusz [Department of Chemistry, University of Gdansk, 80-952 Gdansk (Poland)

    2011-01-07

    The parent negative ions of 5-chlorouracil, UCl{sup -} and 5-fluorouracil, UF{sup -} have been studied using anion photoelectron spectroscopy in order to investigate the electrophilic properties of their corresponding neutral halouracils. The vertical detachment energies (VDE) of these anions and the adiabatic electron affinities (EA) of their neutral molecular counterparts are reported. These results are in good agreement with the results of previously published theoretical calculations. The VDE values for both UCl{sup -} and UF{sup -} and the EA values for their neutral molecular counterparts are much greater than the corresponding values for both anionic and neutral forms of canonical uracil and thymine. These results are consistent with the observation that DNA is more sensitive to radiation damage when thymine is replaced by halouracil. While we also attempted to prepare the parent anion of 5-bromouracil, UBr{sup -}, we did not observe it, the mass spectrum exhibiting only Br{sup -} fragments, i.e., 5-bromouracil apparently underwent dissociative electron attachment. This observation is consistent with a previous assessment, suggesting that 5-bromouracil is the best radio-sensitizer among these three halo-nucleobases.

  6. Anion-Conducting Polymer, Composition, and Membrane

    DOEpatents

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

    2008-10-21

    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.

  7. Anion-conducting polymer, composition, and membrane

    DOEpatents

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

    2010-12-07

    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.

  8. Anion-conducting polymer, composition, and membrane

    DOEpatents

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

    2011-11-22

    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.

  9. Synthesis and study of frustrated oxide and mixed anion materials 

    E-print Network

    Clark, Lucy

    2013-11-28

    Mixed anion systems, such as oxynitrides and oxyfluorides, are an emerging class of interesting materials. The lower stability of mixed anion systems in comparison to oxide materials has had the consequence that this ...

  10. Synthesis of Anion Exchange Polystyrene Membranes for the Electrolysis of

    E-print Network

    Singh, Jayant K.

    Synthesis of Anion Exchange Polystyrene Membranes for the Electrolysis of Sodium Chloride Sonny composite membrane for the electrolysis of sodium chloride to produce sodium hydroxide by selective re: anion exchange membrane, membrane electrolysis, polystyrene Introduction Electrodialysis is a mass

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

    SciTech Connect

    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

    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).

  12. 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...

  13. Bridging the Gap between Fluxomics and Industrial Biotechnology

    PubMed Central

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

    2010-01-01

    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

  14. Uncertainties in Gapped Graphene

    E-print Network

    Eylee Jung; Kwang S. Kim; DaeKil Park

    2012-03-20

    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.

  15. Precision gap particle separator

    DOEpatents

    Benett, William J.; Miles, Robin; Jones II, Leslie M.; Stockton, Cheryl

    2004-06-08

    A system for separating particles entrained in a fluid includes a base with a first channel and a second channel. A precision gap connects the first channel and the second channel. The precision gap is of a size that allows small particles to pass from the first channel into the second channel and prevents large particles from the first channel into the second channel. A cover is positioned over the base unit, the first channel, the precision gap, and the second channel. An port directs the fluid containing the entrained particles into the first channel. An output port directs the large particles out of the first channel. A port connected to the second channel directs the small particles out of the second channel.

  16. Erraticity of Rapidity Gaps

    E-print Network

    Rudolph C. Hwa; Qing-hui Zhang

    1999-12-08

    The use of rapidity gaps is proposed as a measure of the spatial pattern of an event. When the event multiplicity is low, the gaps between neighboring particles carry far more information about an event than multiplicity spikes, which may occur very rarely. Two moments of the gap distrubiton are suggested for characterizing an event. The fluctuations of those moments from event to event are then quantified by an entropy-like measure, which serves to describe erraticity. We use ECOMB to simulate the exclusive rapidity distribution of each event, from which the erraticity measures are calculated. The dependences of those measures on the order of $q$ of the moments provide single-parameter characterizations of erraticity.

  17. Erraticity of rapidity gaps

    SciTech Connect

    Hwa, Rudolph C. [Institute of Theoretical Science and Department of Physics, University of Oregon, Eugene, Oregon 97403-5203 (United States)] [Institute of Theoretical Science and Department of Physics, University of Oregon, Eugene, Oregon 97403-5203 (United States); Zhang, Qing-hui [Institute of Theoretical Science and Department of Physics, University of Oregon, Eugene, Oregon 97403-5203 (United States)] [Institute of Theoretical Science and Department of Physics, University of Oregon, Eugene, Oregon 97403-5203 (United States)

    2000-07-01

    The use of rapidity gaps is proposed as a measure of the spatial pattern of an event. When the event multiplicity is low, the gaps between neighboring particles carry far more information about an event than multiplicity spikes, which may occur very rarely. Two moments of the gap distribution are suggested for characterizing an event. The fluctuations of those moments from event to event are then quantified by an entropy-like measure, which serves to describe erraticity. We use ECOMB to simulate the exclusive rapidity distribution of each event, from which the erraticity measures are calculated. The dependences of those measures on the order q of the moments provide single-parameter characterizations of erraticity. (c) 2000 The American Physical Society.

  18. Skills Gaps in Australian Firms

    ERIC Educational Resources Information Center

    Lindorff, Margaret

    2011-01-01

    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

  19. Origin of d0 magnetism in II-VI and III-V semiconductors by substitutional doping at anion site

    Microsoft Academic Search

    Kesong Yang; Rongqin Wu; Lei Shen; Yuan Ping Feng; Ying Dai; Baibiao Huang

    2010-01-01

    By first-principles electronic structure calculations on carbon and nitrogen doped II-VI and III-V semiconductors, we demonstrate that substitutional doping at anion site by 2p light elements results in spontaneous spin polarization. However, to have a stable magnetic ground state, the 2p orbitals of the dopant must be sufficiently localized in the energy gap of the host semiconductors. The spin magnetic

  20. Understanding and modeling removal of anionic organic contaminants (AOCs) by anion exchange resins.

    PubMed

    Zhang, Huichun; Shields, Anthony J; Jadbabaei, Nastaran; Nelson, Maurice; Pan, Bingjun; Suri, Rominder P S

    2014-07-01

    Ionic organic contaminants (OCs) are a growing concern for water treatment and the environment and are removed inefficiently by many existing technologies. This study examined removal of anionic OCs by anion exchange resins (AXRs) as a promising alternative. Results indicate that two polystyrene AXRs (IRA910 and IRA96) have higher sorption capacities and selectivity than a polyacrylate resin (A860). For the polystyrene resins, selectivity follows: phenolates ? aromatic dicarboxylates > aromatic monocarboxylates > benzenesulfonate > aliphatic carboxylates. This trend can be explained based on hydration energy, the number of exchange groups, and aromaticity and hydrophobicity of the nonpolar moiety (NPM) of the anions. For A860, selectivity only varies within a narrow range (0.13-1.64). Despite the importance of the NPM of the anions, neutral solutes were sorbed much less, indicating synergistic combinations of electrostatic and nonelectrostatic interactions in the overall sorption. By conducting multiple linear regression between Abraham's descriptors and nature log of selectivity, induced dipole-related interactions and electrostatic interactions were found to be the most important interaction forces for sorption of the anions, while solute H-bond basicity has a negative effect. A predictive model was then developed for carboxylates and phenolates based on the poly parameter linear free energy relationships established for a diverse range of 16 anions and 5 neutral solutes, and was validated by accurate prediction of sorption of five test solutes within a wide range of equilibrium concentrations and that of benzoate at different pH. PMID:24877792

  1. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    SciTech Connect

    Jonathan L. Sessler

    2007-09-21

    The major thrust of this project, led by the University of Kansas (Prof. Kristin Bowman-James), entails an exploration of the basic determinants of anion recognition and their application to the design, synthesis, and testing of novel sulfate extractants. A key scientific inspiration for the work comes from the need, codified in simple-to-appreciate terms by the Oak Ridge National Laboratory component of the team (viz. Dr. Bruce Moyer), for chemical entities that can help in the extractive removal of species that have low solubilities in borosilicate glass. Among such species, sulfate anion, has been identified as particularly insidious. Its presence interferes with the vitrification process, thus rendering the remediation of tank waste from, e.g., the Hanford site far more difficult and expensive. The availability of effective extractants, that would allow for the separation of separating sulfate from the major competing anions in the waste, especially nitrate, could allow for pre-vitrification removal of sulfate via liquid-liquid extraction. The efforts at The University of Texas, the subject of this report, have thus concentrated on the development of new sulfate receptors. These systems are designed to increase our basic understanding of anion recognition events and set the stage for the development of viable sulfate anion extractants. In conjunction with the Oak Ridge National Laboratory (ORNL) members of the research team, several of these new receptors were studied as putative extractants, with two of the systems being shown to act as promising synergists for anion exchange.

  2. Closing the Health Gap

    NSDL National Science Digital Library

    2001-01-01

    The US Department of Health and Human Services (HHS) and ABC Radio Networks are working together to help African-Americans gain access to the best possible information regarding health issues. HHS reports that life expectancies for African-Americans lag five years behind expectancies for White Americans. The new Website Closing the Health Gap has links to information on health conditions such as diabetes and cancer as well as consumer health resources that relate to African-Americans' particular needs. Each page offers links, publications, and any news related to the subject, all in an effort to close "the health gap."

  3. DIDS INHIBITION OF SARCOPLASMIC RETICULUM ANION EFFLUX AND CALCIUM TRANSPORT

    E-print Network

    Campbell, Kevin P.

    DIDS INHIBITION OF SARCOPLASMIC RETICULUM ANION EFFLUX AND CALCIUM TRANSPORT Kevin P. Campbell-331 December 23,1980 28031 #12;328 DIDS INHIBITION OF SARCOPLASMIC RETICULUM ANION EFFLUX AND CALCIUM TRANSPORT amounts of calcium when the incubation medium is supplemented with calcium-precipi- tating anions

  4. Detection of Perchlorate Anion on Functionalized Silver Colloids Using Surface-Enhanced Raman Scattering

    SciTech Connect

    Tio, J.; Wang, W.; Gu, B.

    2005-01-01

    Perchlorate anion interferes with the uptake of iodide by the human thyroid gland and consequently disrupts the regulation of metabolism. Chronic exposure to high levels of perchlorate may lead to the formation of thyroid gland tumors. Although the Environmental Protection Agency (EPA) has not set a maximum contaminant level (MCL) for perchlorate, a draft drinking water range of 4-18 ppb based on 2 liter daily consumption of water has been established. The current EPA approved method for detecting perchlorate uses ion chromatography which has a detection limit of ~1ppb and involves lengthy analytical time in the laboratory. A unique combination of the surface-enhanced Raman scattering (SERS) effect and the bifunctional anion exchange resin’s high selectivity may provide an alternative way to detect perchlorate at such low concentrations and with high specificity. SERS, which uses laser excitation of adsorbed perchlorate anions on silver nanoparticles, has been shown to detect perchlorate anions at concentrations as low as 50 ppb. Normal micro-Raman analysis of perchlorate sorbed onto the resin beads has detected an even lower concentration of 10 ppb. In an effort to integrate these two effects, silver nanoparticles were coated with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride, a functional group similar to that found on the resin bead, and subsequently inserted into different perchlorate concentration environments. This method has resulted in perchlorate detection down to ~10 ppb and a more consistent detection of perchlorate anion at ~50 ppb than that of earlier methods. As suggested by the direct insertion of functionalized silver colloids into perchlorate samples, this technique may potentially allow for the development of a probe using on-site Raman spectrometry to detect significantly low concentrations of perchlorate in situ rather than in the laboratory.

  5. [Metabolic syndrome].

    PubMed

    Wirth, A; Rothenfelde, B

    1996-12-01

    The metabolic syndrome consists of a cluster of metabolic diseases which often coexist: abdominal obesity, glucoseintolerance, diabetes mellitus type II, dyslipidemia, hypertension and impaired fibrinolysis. The common pathophysiologic link of these diseases in insulin resistance. All clinical disorders of the metabolic syndrome are risk factors for the vascular system. Since several diseases are present at the same time the risk for atherosclerotic complications such as coronary artery disease and apoplexy is potentiated. As a consequence the costs for direct and indirect health care are high. Besides a genetic predisposition the metabolic syndrome is mainly caused by the typical life style in industrialized countries with high energy and fat intake, physical inactivity, alcohol consumption, smoking, and stress. Therefore, prophylaxis and therapy imply the removal of these factors. In order to be successful experienced physicians and motivated patients are prerequisites. Even more affective than therapy is prophylaxis which is, however, not established in Germany. The metabolic syndrome is up to now not identified as a major health problem neither by the medical profession nor by health insurances and politicians. An effective therapy and prophylaxis would induce far-reaching changes in our health system and diminish health costs. PMID:9082643

  6. Stable and highly persistent quinoxaline-centered metalloorganic radical anions: preparation, structural, spectroscopic, and computational investigations.

    PubMed

    Choua, Sylvie; Djukic, Jean-Pierre; Dalléry, Jérôme; Bieber, André; Welter, Richard; Gisselbrecht, Jean-Paul; Turek, Philippe; Ricard, Louis

    2009-01-01

    Coordination of diazines such as quinoxaline to transition metals stabilizes radical anions generated by chemical or electrochemical cathodic reduction. However, even though various sorts of radical anionic diazines have been subjected to spectroscopic investigations in the recent past, reports combining structural, solid-state electron paramagnetic resonance (EPR) and computational investigations of kinetically stable species are still missing. In this study, four radical anions derived from tricarbonylmanganese- and tricarbonylrhenium-bound quinoxaline chelates, embedded within a triple-decker architecture, have been prepared from neutral substrates by chemical reduction over alkaline metals (K, Rb); the electronic structure of the latter metalloorganic paramagnetic salts was investigated by the means of structural X-ray diffraction analysis, electrochemistry, solution and crystal EPR spectroscopy, and density functional theory (DFT). Unprecedented structures of three manganese-bound and one rhenium-bound quinoxaline-derived paramagnetic salts were obtained from solutions of the corresponding radical anions crystallized in the presence of cryptand 222. It is inferred from a comparative study of the structures of anionic and neutral quinoxaline complexes that reduction does not have any significant impact over the coordination mode of the metal centers and over the overall geometry of the triple-decker architecture. The most notable changes in the radical-anionic metalloorganic species, as compared to the neutral parent molecules, comprise a slight hapticity shift of the metal-bound benzyl moiety and a weak intraannular distortion of the quinoxalyl core. Single-crystal EPR experiments carried out with the rhenium and manganese compounds produced the respective anisotropic g tensor, which was found in each case to be essentially located at the quinoxalyl fragment. Computations, carried out using DFT methods (B3LYP-LANL2DZ and Becke-Perdew-TZP), corroborated the features suggested by structural analysis. Single-point calculation using the B3LYP functional and various basis sets [LANL2DZ, 6-31G(d), 6-311+G(d), and 6-311+G(2d,p)] provided us with values of anisotropic g tensors and hyperfine coupling constants consistent with those determined experimentally. It is inferred from this study that the two metal centers bound to the nitrogen atoms of the quinoxalyl core contribute in the lowering of the HOMO-LUMO gap in the neutral species. The triple-decker arrangement, which combines chelation of the metal, steric protection, and encapsulation of the central quinoxalyl core, is a stabilizing factor that provides a long-lived character to the radical-anionic species. PMID:19053841

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

    E-print Network

    Paris-Sud XI, Université de

    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

  8. Overcoming the Income Gap. The Achievement Gap: Overcoming the Income Gap. Info Brief. Number 47

    ERIC Educational Resources Information Center

    Nelson, Anne

    2006-01-01

    One of the most complex aspects of the achievement gap--one that, by and large, is out of the direct control of educational leaders--is the income gap. Broadly defined, the income gap is the standard of living difference between rich and poor, but in the education system, the gap permeates deeply into many dimensions of a student's progression…

  9. Bridging the Generation Gap

    ERIC Educational Resources Information Center

    Johnson, Susan Moore; Kardos, Susan M.

    2005-01-01

    The lack of instructional continuity in schools negates every effort of principals to provide an environment where all students would be successful. One solution could be to bridge the gap between the professional knowledge and skills of experienced teachers and the energy and fresh ideas of new recruits so that the latter are provided support…

  10. Crossing the Gap

    ERIC Educational Resources Information Center

    Lockette, Tim

    2009-01-01

    In a nation where education is funded largely by local property taxes, schools in wealthy communities have plenty of funds to spend on programs that get their kids ready for college. Schools in poor communities scrimp and save to get the job done--or hope that funding from the state will help fill in the gap. This article describes how students…

  11. The Teaching Gap

    ERIC Educational Resources Information Center

    Feldman, Sandra

    2004-01-01

    One of the most comprehensive studies to highlight the achievement gap between students in the United States and those in many other countries is the Third International Mathematics and Science Study (TIMSS). TIMSS showed that a handful of countries (with Japan near the top) consistently outperformed the others studied (including the United…

  12. STEMMING the Gap

    ERIC Educational Resources Information Center

    Kahler, Jim; Valentine, Nancy

    2011-01-01

    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…

  13. Confronting the Autonomy Gap

    ERIC Educational Resources Information Center

    Adamowski, Steven; Petrilli, Michael J.

    2007-01-01

    "The Autonomy Gap," a recent study by the American Institute for Research and the Thomas B. Fordham Institute, found that many public elementary school principals feel constrained by a bureaucracy that impedes their ability to raise student achievement. Unfortunately, those principals are still held accountable for their school's results--even…

  14. Diastema (Gap between Teeth)

    MedlinePLUS

    ... big for the jaw, teeth will be crowded. Spaces develop for a few other reasons as well. Sometimes some teeth are missing ... the permanent teeth and the jaw size, the spaces can be expected to remain throughout life. Gaps caused by a tongue thrust habit or ...

  15. The Latino Achievement Gap

    ERIC Educational Resources Information Center

    Madrid, E. Michael

    2011-01-01

    In the very near future, Latino students will become the majority in California's public schools and because of their great numbers and presence, the pattern of lackluster academic achievement must be a major concern of teachers, school leaders, and policy makers. Despite having made great strides in narrowing the gap that separated them from…

  16. The Academic Generation Gap

    ERIC Educational Resources Information Center

    Dronzek, Anna

    2008-01-01

    The current generation gap in academia is different--fundamentally shaped by the structural problems of academic employment. The job market has especially exacerbated tensions between senior and junior faculty by ratcheting up expectations and requirements at every stage of the academic career. The disparities have been mentioned often enough to…

  17. Closing the Performance Gap.

    ERIC Educational Resources Information Center

    Riggins, Cheryl G.

    2002-01-01

    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)

  18. Estimating Gender Wage Gaps

    ERIC Educational Resources Information Center

    McDonald, Judith A.; Thornton, Robert J.

    2011-01-01

    Course research projects that use easy-to-access real-world data and that generate findings with which undergraduate students can readily identify are hard to find. The authors describe a project that requires students to estimate the current female-male earnings gap for new college graduates. The project also enables students to see to what…

  19. 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...

  20. Production of warm aluminum cluster anions by femtosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Matsuo, Y.

    2015-02-01

    We report on the production of warm aluminum cluster anions, Al{/n -} (1 ? n ? 26), after femtosecond laser ablation of an aluminum nitride substrate. Large cluster anions of n ? 8 suffer metastable dissociation after their production, which indicates the internal energy of the cluster anions is high enough for the dissociation of an Al atom. We find that the efficiency of metastable dissociation is dependent on the size of cluster anions and the dependence can be rationalized by the dissociation energy of an Al atom from the cluster anions calculated with thermochemical data of the clusters.

  1. Nanoheterostructure cation exchange: anionic framework conservation.

    PubMed

    Jain, Prashant K; Amirav, Lilac; Aloni, Shaul; Alivisatos, A Paul

    2010-07-28

    In ionic nanocrystals the cationic sublattice can be replaced with a different metal ion via a fast, simple, and reversible place exchange, allowing postsynthetic modification of the composition of the nanocrystal, while preserving its size and shape. Here, we demonstrate that, during such an exchange, the anionic framework of the crystal is preserved. When applied to nanoheterostructures, this phenomenon ensures that compositional interfaces within the heterostructure are conserved throughout the transformation. For instance, a morphology composed of a CdSe nanocrystal embedded in a CdS rod (CdSe/CdS) was exchanged to a PbSe/PbS nanorod via a Cu(2)Se/Cu(2)S structure. During every exchange cycle, the seed size and position within the nanorod were preserved, as evident by excitonic features, Z-contrast imaging, and elemental line scans. Anionic framework conservation extends the domain of cation exchange to the design of more complex and unique nanostructures. PMID:20593896

  2. Anion photoelectron spectroscopy of radicals and clusters

    SciTech Connect

    Travis, Taylor R.

    1999-12-16

    Anion photoelectron spectroscopy is used to study free radicals and clusters. The low-lying {sup 2}{Sigma} and {sup 2}{Pi} states of C{sub 2n}H (n = 1--4) have been studied. The anion photoelectron spectra yielded electron affinities, term values, and vibrational frequencies for these combustion and astrophysically relevant species. Photoelectron angular distributions allowed the author to correctly assign the electronic symmetry of the ground and first excited states and to assess the degree of vibronic coupling in C{sub 2}H and C{sub 4}H. Other radicals studied include NCN and I{sub 3}. The author was able to observe the low-lying singlet and triplet states of NCN for the first time. Measurement of the electron affinity of I{sub 3} revealed that it has a bound ground state and attachment of an argon atom to this moiety enabled him to resolve the symmetric stretching progression.

  3. The organic anion transporter (OAT) family: a systems biology perspective.

    PubMed

    Nigam, Sanjay K; Bush, Kevin T; Martovetsky, Gleb; Ahn, Sun-Young; Liu, Henry C; Richard, Erin; Bhatnagar, Vibha; Wu, Wei

    2015-01-01

    The organic anion transporter (OAT) subfamily, which constitutes roughly half of the SLC22 (solute carrier 22) transporter family, has received a great deal of attention because of its role in handling of common drugs (antibiotics, antivirals, diuretics, nonsteroidal anti-inflammatory drugs), toxins (mercury, aristolochic acid), and nutrients (vitamins, flavonoids). Oats are expressed in many tissues, including kidney, liver, choroid plexus, olfactory mucosa, brain, retina, and placenta. Recent metabolomics and microarray data from Oat1 [Slc22a6, originally identified as NKT (novel kidney transporter)] and Oat3 (Slc22a8) knockouts, as well as systems biology studies, indicate that this pathway plays a central role in the metabolism and handling of gut microbiome metabolites as well as putative uremic toxins of kidney disease. Nuclear receptors and other transcription factors, such as Hnf4? and Hnf1?, appear to regulate the expression of certain Oats in conjunction with phase I and phase II drug metabolizing enzymes. Some Oats have a strong selectivity for particular signaling molecules, including cyclic nucleotides, conjugated sex steroids, odorants, uric acid, and prostaglandins and/or their metabolites. According to the "Remote Sensing and Signaling Hypothesis," which is elaborated in detail here, Oats may function in remote interorgan communication by regulating levels of signaling molecules and key metabolites in tissues and body fluids. Oats may also play a major role in interorganismal communication (via movement of small molecules across the intestine, placental barrier, into breast milk, and volatile odorants into the urine). The role of various Oat isoforms in systems physiology appears quite complex, and their ramifications are discussed in the context of remote sensing and signaling. PMID:25540139

  4. Anions in scapolite: a FTIR study

    NASA Astrophysics Data System (ADS)

    Kuhn, B.; Soares, M.; Günther, D.; Reusser, E.

    2003-04-01

    Scapolites from siliceous and argillaceous carbonates were chemically analysed for major (electron microprobe) and trace (LA-ICP-MS) elements. As both methods do not permit the direct measurement of C, H, O, large uncertainties exist concerning the anionic species which may be incorporated. To obtain a better idea about the nature of the anions, a set of scapolites were therefore analysed by FTIR. The set of analysed scapolites consists of three gem quality single crystals from Tanzania as well as some scapolites from a number of different metacarbonate occurrences in the Central Alps (Switzerland). The scapolites from Tanzania contain appreciable Cl (2.5~-- 3.6 wt%) and traces of S (<0.4~wt%). In the scapolites from the Central Alps (Switzerland) only traces of Cl (<0.13~wt%) could be measured and no S. The formation of scapolite from plagioclase and calcite as seen in thin sections suggests that most of the anions are CO_32-. Donnay et al. (1978) suggested that H could be present in scapolite as HCl in marialitic and as HCO_3- or HSO_4- in meionitic end members. To detect these different anion complexes, FTIR-spectroscopy was used. The infrared reflectance spectra of the alpine samples showed a strong double peak at ? 1500 cm-1 which can be assigned to the CO_3-group. This mode can hardly be detected in the marialitic samples from Tanzania. Sulphate-sulphur was found to be present in the Tanzanian scapolites but was not detected in the other samples.

  5. Aza crown ether compounds as anion receptors

    SciTech Connect

    Lee, Hung Sui (East Setauket, NY); Yang, Xiao-Oing (Port Jefferson Station, NY); McBreen, James (Bellport, NY)

    1998-08-04

    A family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the new family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of LI.sup.+ ion in alkali metal batteries.

  6. Aza crown ether compounds as anion receptors

    DOEpatents

    Lee, H.S.; Yang, X.O.; McBreen, J.

    1998-08-04

    A family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the new family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of LI{sup +} ion in alkali metal batteries. 3 figs.

  7. Deuterium anions in inertial electrostatic confinement devices

    Microsoft Academic Search

    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

    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.

  8. An NMR study of anion binding to yeast phosphoglycerate kinase.

    PubMed

    Fairbrother, W J; Graham, H C; Williams, R J

    1990-05-31

    Anion binding to yeast phosphoglycerate kinase has been investigated using 1H-NMR spectroscopy. The use of anionic paramagnetic probes. [Cr(CN)6]3- and [Fe(CN)6]3-, has enabled the location of the primary anion binding site in the 'basic-patch' region of the amino-terminal domain. The anions interact most closely with Arg-65 and Arg-168. The binding of these and a variety of other anions to this site is directly competitive with the binding of the substrate, 3-phosphoglycerate. Binding of 3-phosphoglycerate and 1.3-bisphosphoglycerate is, however, stronger than expected on the basis of anionic charge and causes conformational changes in the protein not seen with any of the other simple spherical anions investigated. This must be part, at least, of the substrate specificity. Evidence for a secondary anion binding site involving the side chains of surface lysine residues is also presented. It is suggested that the primary anion site is responsible for the observed activation by anions at low concentrations while the secondary site leads to inhibition at higher anion concentrations. The kinetics fit these deductions and a scheme for kinase activity is presented. PMID:2194794

  9. Anion selectivity in ion exchange reactions with surface functionalized ionosilicas.

    PubMed

    Petrova, Maria; Guigue, Mireille; Venault, Laurent; Moisy, Philippe; Hesemann, Peter

    2015-04-01

    Mesoporous imidazolium functionalized surface functionalized ionosilicas have been investigated as anion exchange materials for the adsorption of oxo-anions in aqueous media. We studied particularly pertechnetate adsorption and could show that solids bearing long chain substituted imidazolium groups are highly efficient anion exchange materials often displaying high distribution coefficients between solid and liquid phases. We observed that the distribution coefficient of pertechnetate is a function of the presence of competing anionic species. As a consequence, our experiments allowed reproducing experimentally Hofmeister's series. However, pertechnetate adsorption on the material can completely be inhibited in the presence of highly fluorinated anions such as bis(trifluoromethylsulfonyl)amide (NTf2). This behaviour indicates a particularly imidazophilic behaviour of these anions, which have a particular importance due to their use in water immiscible ionic liquids. Finally, the adsorption process has been shown to be reversible. This feature is of importance in view of the regeneration of the anion exchange material. PMID:25793553

  10. Metabolic Disorders

    MedlinePLUS

    ... your body's fuel. Your body can use this fuel right away, or it can store the energy in your body tissues, such as your liver, muscles, and body fat. A metabolic disorder occurs when abnormal chemical reactions in your body disrupt this process. When this ...

  11. Metabolic Syndrome

    MedlinePLUS

    ... syndrome can lead to. Back Continue Changing Your Course In the case of metabolic syndrome, making a couple of lifestyle changes is the best way to keep yourself on a track to good health. Here are the top ones: Drop excess pounds. If you're overweight, ...

  12. Metabolic Syndrome

    MedlinePLUS

    ... your waist Not all doctors agree on the definition or cause of metabolic syndrome. The cause might be insulin resistance. Insulin is a hormone your body produces to help you turn sugar from food into energy for your body. If you are insulin resistant, ...

  13. Hydrogen sulfide anion regulates redox signaling via electrophile sulfhydration

    PubMed Central

    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

    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

  14. Hydrogen sulfide anion regulates redox signaling via electrophile sulfhydration.

    PubMed

    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

    2012-08-01

    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

  15. Photonic Band Gap

    NSDL National Science Digital Library

    Ho, Seng-Tiong

    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.

  16. Air-gap heterostructures

    SciTech Connect

    Heyn, Ch.; Schmidt, M.; Schwaiger, S.; Stemmann, A.; Mendach, S.; Hansen, W. [Institut fuer Angewandte Physik und Zentrum fuer Mikrostrukturforschung, Jungiusstrasse 11, D-20355 Hamburg (Germany)

    2011-01-17

    We demonstrate the fabrication of thin GaAs layers which quasi hover above the underlying GaAs substrate. The hovering layers have a perfect epitaxial relationship to the substrate crystal lattice and are connected to the substrate surface only by lattice matched nanopillars of low density. These air-gap heterostructures are created by combining in situ molecular beam epitaxy compatible self-assembled droplet-etching and ex situ selective wet-chemical etching.

  17. Bridging the Gap

    NSDL National Science Digital Library

    Grace Eason

    2004-11-01

    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.

  18. Filling the launch gap

    Microsoft Academic Search

    S. Hoeser

    1986-01-01

    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

  19. Evidence for anionic cation transport of lithium, sodium and potassium across the human erythrocyte membrane induced by divalent anions.

    PubMed

    Becker, B F; Duhm, J

    1978-09-01

    1. The passive net transport of Li+ and Na+ across the human red cell membrane was accelerated by the divalent anions carbonate, sulphite, oxalate, phosphite and malonate. Phthalate, maleate, sulphate and succinate were found additionally to stimulate downhill transport of K+. Marked differences in anion efficacy and selectivity were observed. 2. The effects of these 'carbonate type' anions were reversible and fully blocked by SITS, dipyridamole and other inhibitors of anion transfer. 3. Cation transport acceleration induced by the monovalent anions salicylate, benzoate, thiocyanate and 2,4-dinitrophenol were inhibited by dipyridamole, but not affected by SITS. A great number of mono- and polyvalent anions were without detectable influence on Li+ transport. 4. Li+ net uptake induced by oxalate exhibited a pH dependence similar to that reported for halide self exchange. 5. Transport acceleration by carbonate type anions displayed a linear, 1:1 dependence on the concentrations of both the anion and the cation and was symmetric with respect to the two sides of the membrane. 6. It is concluded that the divalent carbonate type anions form singly charged, negative 1:1 ion pairs with the respective alkali metal cations, the ion pairs traversing the red cell membrane via the anion exchange pathway. This concept of anionic formation of some of the ion pairs considered. The relative efficacies and cation selectivities of polyvalent anions can largely be explained on the basis of electrostatic interactions governing ion pair formation. However, the chelating properties, structural flexibility, polarizability of the anions and the accessibility of the ion pairs to the anion exchange pathway need also be considered. 7. An exchange of NaCO-3 ion pairs for internal HCO-3 or Cl- is discussed as a possible mode of cellular pH regulation. PMID:31458

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

    PubMed

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

    2001-05-01

    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

  1. An Innovative Anion Regulation Strategy for Energy Bands of Semiconductors: A Case from Bi2O3 to Bi2O(OH)2SO4

    PubMed Central

    Tian, Hao; Teng, Fei; Xu, Juan; Lou, Sunqi; Li, Na; Zhao, Yunxuan; Chen, Mindong

    2015-01-01

    How to develop a new, efficient photo catalyst is still a big challenge to us. A suitable band gap is the key for light absorption of semiconductor. Herein, an innovative anion intercalation strategy is, for the first time, developed to regulate the energy band of semiconductor. Typically, we introduce a layered sulfate compound (Bi2O(OH)2SO4) as a new photo catalyst, which has not been known before. Both partial density of states (PDOS) and total density of states (TDOS) have demonstrated that compared with Bi2O3 (2.85?eV), the band gap of Bi2O(OH)2SO4 has been widened to 4.18?eV by the intercalation of sulfate anion. Moreover, the band gap width of oxyacid salt compound is mainly predominated by the number of the outmost electrons (NOE) of central atom of anion. This study suggests that new photo catalysts can be developed by grouping anions with the existing oxides or sulfides. PMID:25597769

  2. An Innovative Anion Regulation Strategy for Energy Bands of Semiconductors: A Case from Bi2O3 to Bi2O(OH)2SO4

    NASA Astrophysics Data System (ADS)

    Tian, Hao; Teng, Fei; Xu, Juan; Lou, Sunqi; Li, Na; Zhao, Yunxuan; Chen, Mindong

    2015-01-01

    How to develop a new, efficient photo catalyst is still a big challenge to us. A suitable band gap is the key for light absorption of semiconductor. Herein, an innovative anion intercalation strategy is, for the first time, developed to regulate the energy band of semiconductor. Typically, we introduce a layered sulfate compound (Bi2O(OH)2SO4) as a new photo catalyst, which has not been known before. Both partial density of states (PDOS) and total density of states (TDOS) have demonstrated that compared with Bi2O3 (2.85 eV), the band gap of Bi2O(OH)2SO4 has been widened to 4.18 eV by the intercalation of sulfate anion. Moreover, the band gap width of oxyacid salt compound is mainly predominated by the number of the outmost electrons (NOE) of central atom of anion. This study suggests that new photo catalysts can be developed by grouping anions with the existing oxides or sulfides.

  3. An innovative anion regulation strategy for energy bands of semiconductors: a case from Bi2O3 to Bi2O(OH)2SO4.

    PubMed

    Tian, Hao; Teng, Fei; Xu, Juan; Lou, Sunqi; Li, Na; Zhao, Yunxuan; Chen, Mindong

    2015-01-01

    How to develop a new, efficient photo catalyst is still a big challenge to us. A suitable band gap is the key for light absorption of semiconductor. Herein, an innovative anion intercalation strategy is, for the first time, developed to regulate the energy band of semiconductor. Typically, we introduce a layered sulfate compound (Bi2O(OH)2SO4) as a new photo catalyst, which has not been known before. Both partial density of states (PDOS) and total density of states (TDOS) have demonstrated that compared with Bi2O3 (2.85 eV), the band gap of Bi2O(OH)2SO4 has been widened to 4.18 eV by the intercalation of sulfate anion. Moreover, the band gap width of oxyacid salt compound is mainly predominated by the number of the outmost electrons (NOE) of central atom of anion. This study suggests that new photo catalysts can be developed by grouping anions with the existing oxides or sulfides. PMID:25597769

  4. Giardia Metabolism

    Microsoft Academic Search

    Edward L. Jarroll; Harry van Keulen; Timothy A. Paget; Donald G. Lindmark

    \\u000a This chapter describes key aspects of our basic knowledge of Giardia metabolism. It is well known that this organism has minimal biosynthetic capacity: it lacks de novo lipid, de novo purine,\\u000a and de novo pyrimidine syntheses (relying solely on salvage pathways). Giardia also lacks mitochondria and cytochrome-mediated oxidative phosphorylation and thus trophozoites use glycolysis (from glucose\\u000a only) and the arginine

  5. Closing gaps: linking elements that control stomatal movement.

    PubMed

    Kollist, Hannes; Nuhkat, Maris; Roelfsema, M Rob G

    2014-07-01

    Stomata are an attractive experimental system in plant biology, because the responses of guard cells to environmental signals can be directly linked to changes in the aperture of stomatal pores. In this review, the mechanics of stomatal movement are discussed in relation to ion transport in guard cells. Emphasis is placed on the ion pumps, transporters, and channels in the plasma membrane, as well as in the vacuolar membrane. The biophysical properties of transport proteins for H(+), K(+), Ca(2+), and anions are discussed and related to their function in guard cells during stomatal movements. Guard cell signaling pathways for ABA, CO2, ozone, microbe-associated molecular patterns (MAMPs) and blue light are presented. Special attention is given to the regulation of the slow anion channel (SLAC) and SLAC homolog (SLAH)-type anion channels by the ABA signalosome. Over the last decade, several knowledge gaps in the regulation of ion transport in guard cells have been closed. The current state of knowledge is an excellent starting point for tackling important open questions concerning stress tolerance in plants. PMID:24800691

  6. Bridging Gaps Between Refractory Tiles

    NASA Technical Reports Server (NTRS)

    Haney, J. W. J.

    1982-01-01

    Excessively large gaps between tiles on Space Shuttle eliminated without time-consuming and costly procedure of removing and replacing tiles. Ceramic tile silver is bonded in gap. Bonded silver prevents airframe under gap from getting too hot during reentry and presents aerodynamically smooth exterior surface.

  7. Structural evolution of small ruthenium cluster anions

    NASA Astrophysics Data System (ADS)

    Waldt, Eugen; Hehn, Anna-Sophia; Ahlrichs, Reinhart; Kappes, Manfred M.; Schooss, Detlef

    2015-01-01

    The structures of ruthenium cluster anions have been investigated using a combination of trapped ion electron diffraction and density functional theory computations in the size range from eight to twenty atoms. In this size range, three different structural motifs are found: Ru8--Ru12- have simple cubic structures, Ru13--Ru16- form double layered hexagonal structures, and larger clusters form close packed motifs. For Ru17-, we find hexagonal close packed stacking, whereas octahedral structures occur for Ru18--Ru20-. Our calculations also predict simple cubic structures for the smaller clusters Ru4--Ru7-, which were not accessible to electron diffraction measurements.

  8. Development of synthetic membrane transporters for anions

    PubMed Central

    Davis, Anthony P.; Sheppard, David N.; Smith, Bradley D.

    2010-01-01

    The development of low molecular weight anion transporters is an emerging topic in supramolecular chemistry. The major focus of this tutorial review is on synthetic chloride transport systems that operate in vesicle and cell membranes. The transporters alter transmembrane concentration gradients, and thus they have applications as reagents for cell biology research and as potential chemotherapeutic agents. The molecular designs include monomolecular channels, self-assembled channels and mobile carriers. Also discussed are the experimental assays that measure transport rates across model bilayer membranes. PMID:17264935

  9. A model for anionic surfactant sorption

    SciTech Connect

    Di Toro, D.M. (HydroQual Inc., Mahwah, NJ (USA) Manhattan College, Bronx, NY (USA)); Dodge, L.J. (HydroQual Inc., Mahwah, NJ (USA)); Hand, V.C. (Procter and Gamble Co., Cincinnati, OH (USA))

    1990-07-01

    A model for anionic surfactant sorption to soils, sediments, and sludges is proposed. It relates the partition coefficient that characterizes the linear, low-concentration, portion of the isotherm to the surfactant critical micelle concentration as a measure of hydrophobicity, to either the organic carbon fraction or the cation-exchange capacity of the particles, and to the particle concentration itself. The particle interaction model is used as the framework for the latter effect. The available data span the low particle concentration region as well as the asymptotic region where only particle concentration controls the extent of sorption.

  10. Probes for anionic cell surface detection

    DOEpatents

    Smith, Bradley D.

    2013-03-05

    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.

  11. Process for removing sulfate anions from waste water

    DOEpatents

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

    1997-01-01

    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.

  12. Zero-point energy effects in anion solvation shells.

    PubMed

    Habershon, Scott

    2014-05-21

    By comparing classical and quantum-mechanical (path-integral-based) molecular simulations of solvated halide anions X(-) [X = F, Cl, Br and I], we identify an ion-specific quantum contribution to anion-water hydrogen-bond dynamics; this effect has not been identified in previous simulation studies. For anions such as fluoride, which strongly bind water molecules in the first solvation shell, quantum simulations exhibit hydrogen-bond dynamics nearly 40% faster than the corresponding classical results, whereas those anions which form a weakly bound solvation shell, such as iodide, exhibit a quantum effect of around 10%. This observation can be rationalized by considering the different zero-point energy (ZPE) of the water vibrational modes in the first solvation shell; for strongly binding anions, the ZPE of bound water molecules is larger, giving rise to faster dynamics in quantum simulations. These results are consistent with experimental investigations of anion-bound water vibrational and reorientational motion. PMID:24709978

  13. Retention of anions on silica-based metalloporphyrin stationary phases.

    PubMed

    Biesaga, Magdalena; Stolarczyk, Elzbieta; Pyrzy?ska, Krystyna; Trojanowicz, Marek

    2002-02-01

    The silica-based Fe(III)-protoporphyrin and Zn-tetraphenylporphyrin stationary phases were examined for the HPLC separation of anions. The retention of nine common inorganic anions as well as benzoate anion (BA) and its hydroxy analogues (HBA) was examined using tartrate, acetate, and succinate eluents. The retention factors of inorganic anions on the FeProP stationary phase were in the order Cl- < NO3- < ClO4- < I- < SCN- and for organic anions benzoate < p-hydroxybenzoate < m-hydoxybenzoate < o-hydroxybenzoate. The retention factors of organic anions examined for a ZnTPP column were in the order p-HBA < m-HBA < BA < o-HBA. PMID:11874117

  14. The chemistry of molecular anions in circumstellar sources

    NASA Astrophysics Data System (ADS)

    Agúndez, Marcelino; Cernicharo, José; Guélin, Michel

    2015-01-01

    The detection of negatively charged molecules in the interstellar and circumstellar medium in the past four years has been one of the most impacting surprises in the area of molecular astrophysics. It has motivated the interest of astronomers, physicists, and chemists on the study of the spectroscopy, chemical kinetics, and prevalence of molecular anions in the different astronomical regions. Up to six different molecular anions have been discovered in space to date, the last one being the small ion CN-, which has been observed in the envelope of the carbon star IRC +10216 and which contrary to the other larger anions is not formed by electron attachment to CN, but through reactions of large carbon anions with nitrogen atoms. Here we briefly review the current status of our knowledge of the chemistry of molecular anions in space, with particular emphasis on the circumstellar source IRC +10216, which to date is the astronomical source harboring the largest variety of anions.

  15. Sodium Bicarbonate Therapy in Patients with Metabolic Acidosis

    PubMed Central

    Adeva-Andany, María M.; Fernández-Fernández, Carlos; Mouriño-Bayolo, David; Castro-Quintela, Elvira; Domínguez-Montero, Alberto

    2014-01-01

    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. PMID:25405229

  16. PROGRESS 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 oxoanions of environmental importance and specifically those found in high level waste tanks. Polyammonium macrocycles as receptors and nitrate as anion were the focus of the first phase of this project. A second pha...

  17. Unexpectedly strong anion-? interactions on the graphene flakes.

    PubMed

    Shi, Guosheng; Ding, Yihong; Fang, Haiping

    2012-05-30

    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

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

    Microsoft Academic Search

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

    2010-01-01

    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

  19. Gapped Domain Walls, Gapped Boundaries, and Topological Degeneracy

    NASA Astrophysics Data System (ADS)

    Lan, Tian; Wang, Juven C.; Wen, Xiao-Gang

    2015-02-01

    Gapped domain walls, as topological line defects between (2 +1 )D topologically ordered states, are examined. We provide simple criteria to determine the existence of gapped domain walls, which apply to both Abelian and non-Abelian topological orders. Our criteria also determine which (2 +1 )D topological orders must have gapless edge modes, namely, which (1 +1 )D global gravitational anomalies ensure gaplessness. Furthermore, we introduce a new mathematical object, the tunneling matrix W , whose entries are the fusion-space dimensions Wi a , to label different types of gapped domain walls. By studying many examples, we find evidence that the tunneling matrices are powerful quantities to classify different types of gapped domain walls. Since a gapped boundary is a gapped domain wall between a bulk topological order and the vacuum, regarded as the trivial topological order, our theory of gapped domain walls inclusively contains the theory of gapped boundaries. In addition, we derive a topological ground state degeneracy formula, applied to arbitrary orientable spatial 2-manifolds with gapped domain walls, including closed 2-manifolds and open 2-manifolds with gapped boundaries.

  20. Identification and characterization of anion binding sites in RNA

    PubMed Central

    Kieft, Jeffrey S.; Chase, Elaine; Costantino, David A.; Golden, Barbara L.

    2010-01-01

    Although RNA molecules are highly negatively charged, anions have been observed bound to RNA in crystal structures. It has been proposed that anion binding sites found within isolated RNAs represent regions of the molecule that could be involved in intermolecular interactions, indicating potential contact points for negatively charged amino acids from proteins or phosphate groups from an RNA. Several types of anion binding sites have been cataloged based on available structures. However, currently there is no method for unambiguously assigning anions to crystallographic electron density, and this has precluded more detailed analysis of RNA–anion interaction motifs and their significance. We therefore soaked selenate into two different types of RNA crystals and used the anomalous signal from these anions to identify binding sites in these RNA molecules unambiguously. Examination of these sites and comparison with other suspected anion binding sites reveals features of anion binding motifs, and shows that selenate may be a useful tool for studying RNA–anion interactions. PMID:20410239

  1. Purification Or Organic Acids Using Anion Exchange Chromatography.

    DOEpatents

    Ponnampalam; Elankovan (Okemos, MI)

    2001-09-04

    Disclosed is a cost-effective method for purifying and acidifying carboxylic acids, including organic acids and amino acids. The method involves removing impurities by allowing the anionic form of the carboxylic acid to bind to an anion exchange column and washing the column. The carboxylic anion is displaced as carboxylic acid by washing the resin with a strong inorganic anion. This method is effective in removing organic carboxylic acids and amino acids from a variety of industrial sources, including fermentation broths, hydrolysates, and waste streams.

  2. Aluminum Zintl anion moieties within sodium aluminum clusters

    SciTech Connect

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Grubisic, Andrej; Li, Xiang; Ganteför, Gerd; Bowen, Kit H., E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Schnöckel, Hansgeorg [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany)] [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Eichhorn, Bryan W. [Department of Chemistry, University of Maryland at College Park, College Park, Maryland 20742 (United States)] [Department of Chemistry, University of Maryland at College Park, College Park, Maryland 20742 (United States); Lee, Mal-Soon; Jena, P. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Kandalam, Anil K., E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Physics, West Chester University of Pennsylvania, West Chester, Pennsylvania 19383 (United States); Kiran, Boggavarapu, E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States)] [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States)

    2014-02-07

    Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have established that aluminum moieties within selected sodium-aluminum clusters are Zintl anions. Sodium–aluminum cluster anions, Na{sub m}Al{sub n}{sup ?}, were generated in a pulsed arc discharge source. After mass selection, their photoelectron spectra were measured by a magnetic bottle, electron energy analyzer. Calculations on a select sub-set of stoichiometries provided geometric structures and full charge analyses for both cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra), and fragment molecular orbital based correlation diagrams.

  3. An intracellular anion channel critical for pigmentation.

    PubMed

    Bellono, Nicholas W; Escobar, Iliana E; Lefkovith, Ariel J; Marks, Michael S; Oancea, Elena

    2014-01-01

    Intracellular ion channels are essential regulators of organellar and cellular function, yet the molecular identity and physiological role of many of these channels remains elusive. In particular, no ion channel has been characterized in melanosomes, organelles that produce and store the major mammalian pigment melanin. Defects in melanosome function cause albinism, characterized by vision and pigmentation deficits, impaired retinal development, and increased susceptibility to skin and eye cancers. The most common form of albinism is caused by mutations in oculocutaneous albinism II (OCA2), a melanosome-specific transmembrane protein with unknown function. Here we used direct patch-clamp of skin and eye melanosomes to identify a novel chloride-selective anion conductance mediated by OCA2 and required for melanin production. Expression of OCA2 increases organelle pH, suggesting that the chloride channel might regulate melanin synthesis by modulating melanosome pH. Thus, a melanosomal anion channel that requires OCA2 is essential for skin and eye pigmentation. PMID:25513726

  4. Anionic derivatives of uracil: fragmentation and reactivity.

    PubMed

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

    2014-09-01

    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

  5. An intracellular anion channel critical for pigmentation

    PubMed Central

    Bellono, Nicholas W; Escobar, Iliana E; Lefkovith, Ariel J; Marks, Michael S; Oancea, Elena

    2014-01-01

    Intracellular ion channels are essential regulators of organellar and cellular function, yet the molecular identity and physiological role of many of these channels remains elusive. In particular, no ion channel has been characterized in melanosomes, organelles that produce and store the major mammalian pigment melanin. Defects in melanosome function cause albinism, characterized by vision and pigmentation deficits, impaired retinal development, and increased susceptibility to skin and eye cancers. The most common form of albinism is caused by mutations in oculocutaneous albinism II (OCA2), a melanosome-specific transmembrane protein with unknown function. Here we used direct patch-clamp of skin and eye melanosomes to identify a novel chloride-selective anion conductance mediated by OCA2 and required for melanin production. Expression of OCA2 increases organelle pH, suggesting that the chloride channel might regulate melanin synthesis by modulating melanosome pH. Thus, a melanosomal anion channel that requires OCA2 is essential for skin and eye pigmentation. DOI: http://dx.doi.org/10.7554/eLife.04543.001 PMID:25513726

  6. Anion selectivity by the sodium iodide symporter.

    PubMed

    Van Sande, J; Massart, C; Beauwens, R; Schoutens, A; Costagliola, S; Dumont, J E; Wolff, J

    2003-01-01

    The iodide transporter of the thyroid (NIS) has been cloned by the group of Carrasco. The NIS-mediated transport was studied by electrophysiological methods in NIS-expressing Xenopus oocytes. Using this method, the anion selectivity of NIS was different from that previously reported for thyroid cells, whereas perchlorate and perrhenate were found not transported. In this study we compared the properties of human NIS, stably transfected in COS-7 cells to those of the transport in a thyroid cell line, the FRTL5 cells, by measuring the transport directly. We measured the uptake of (125)I(-), (186)ReO(4)(-), and (99m)TcO(4)(-) and studied the effect on it of known competing anions, i.e. ClO(4)(-), SCN(-), ClO(3)(-), ReO(4)(-), and Br(-). We conclude that the properties of the NIS transporter account by themselves for the properties of the thyroid iodide transporter as described previously in thyroid slices. The order of affinity was: ClO(4)(-) > ReO(4)(-) > I(-) >/= SCN(-) > ClO(3)(-) > Br(-). NIS is also inhibited by dysidenin (as in dog thyroid). PMID:12488351

  7. Deuterium anions in inertial electrostatic confinement devices

    NASA Astrophysics Data System (ADS)

    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

    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?A/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 0.7cm2 . 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.

  8. Deuterium anions in inertial electrostatic confinement devices.

    PubMed

    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

    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

  9. Condensation of [Si3O9]6- anions in the solid state to the dimeric cyclotrisilicate anion [Si6O17]10-.

    PubMed

    Hoffmann, Stefan; Fässler, Thomas F

    2006-09-18

    The structure of the silicate Rb10[Si6O17] containing a novel dimeric cyclotrisilicate anion is reported. The compound is formed by the reaction of a mixture of SiO2 and Rb at temperatures above 700 degrees C. Systematic investigations by means of differential thermal analysis and temperature-dependent powder X-ray diffraction experiments revealed that the new compound evolved from Rb6[Si3O9], which occurred as an intermediate product. Thus, the dimeric anion [Si6O17]10- is formed by condensation of the monomeric cyclotrisilicate [Si3O9]6-. For both silicates, [Si6O17]10- and [Si3O9]6-, the characteristic ring vibration modes were observed in the IR spectrum. The structure of Rb10[Si6O17] was solved and refined from single-crystal X-ray diffraction data in the orthorhombic space group Pbca (No. 61). Synthesis and structure determination of Rb10[Si6O17] bridge the gap to show that the recently reported structures of Rb14[Si4][Si6O17] and Rb14[Ge4][Si6O17] are indeed fascinating intergrowth structures of the stable oxide Rb10[Si6O17] and the Zintl phases RbSi (Rb4Si4) and RbGe (Rb4Ge4), respectively. PMID:16961392

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

    PubMed

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

    2013-12-17

    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

  11. 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 ... Diabetes High Blood Pressure My Life Check Heart360® Metabolic Syndrome • Home • About Metabolic Syndrome • Why Metabolic Syndrome Matters • ...

  12. 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.

  13. Filling the launch gap

    NASA Astrophysics Data System (ADS)

    Hoeser, S.

    1986-05-01

    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.

  14. Fluorescence anisotropy of tyrosinate anion using one-, two- and three-photon excitation: tyrosinate anion fluorescence.

    PubMed

    Kierdaszuk, Borys

    2013-03-01

    We examined the emission spectra and steady-state anisotropy of tyrosinate anion fluorescence with one-photon (250-310 nm), two-photon (570-620 nm) and three-photon (750-930 nm) excitation. Similar emission spectra of the neutral (pH 7.2) and anionic (pH 13) forms of N-acetyl-L-tyrosinamide (NATyrA) (pKa 10.6) were observed for all modes of excitation, with the maxima at 302 and 352 nm, respectively. Two-photon excitation (2PE) and three-photon excitation (3PE) spectra of the anionic form were the same as that for one-photon excitation (1PE). In contrast, 2PE spectrum from the neutral form showed ~30-nm shift to shorter wavelengths relative to 1PE spectrum (?max 275 nm) at two-photon energy (550 nm), the latter being overlapped with 3PE spectrum, both at two-photon energy (550 nm). Two-photon cross-sections for NATyrA anion at 565-580 nm were 10 % of that for N-acetyl-L-tryptophanamide (NATrpA), and increased to 90 % at 610 nm, while for the neutral form of NATyrA decreased from 2 % of that for NATrpA at 570 nm to near zero at 585 nm. Surprisingly, the fundamental anisotropy of NATyrA anion in vitrified solution at -60 °C was ~0.05 for 2PE at 610 nm as compared to near 0.3 for 1PE at 305 nm, and wavelength-dependence appears to be a basic feature of its anisotropy. In contrast, the 3PE anisotropy at 900 nm was about 0.5, and 3PE and 1PE anisotropy values appear to be related by the cos(6) ? to cos(2) ? photoselection factor (approx. 10/6) independently of excitation wavelength. Attention is drawn to the possible effect of tyrosinate anions in proteins on their multi-photon induced fluorescence emission and excitation spectra as well as excitation anisotropy spectra. PMID:23233051

  15. Organic anion transporting polypeptide mediates organic anion/HCO3- exchange.

    PubMed

    Satlin, L M; Amin, V; Wolkoff, A W

    1997-10-17

    Organic anion transporting polypeptide (oatp) is an integral membrane protein cloned from rat liver that mediates Na+-independent transport of organic anions such as sulfobromophthalein and taurocholic acid. Previous studies in rat hepatocytes suggested that organic anion uptake is associated with base exchange. To better characterize the mechanism of oatp-mediated organic anion uptake, we examined transport of taurocholate in a HeLa cell line stably transfected with oatp under the regulation of a zinc-inducible promoter (Shi, X., Bai, S., Ford, A. C., Burk, R. D., Jacquemin, E., Hagenbuch, B., Meier, P. J., and Wolkoff, A. W. (1995) J. Biol. Chem. 270, 25591-25595). Whereas noninduced transfected cells showed virtually no uptake of [3H]taurocholate, taurocholate uptake by induced cells was Na+-independent and saturable (Km = 19.4 +/- 3.3 microM; Vmax = 62.2 +/- 1.4 pmol/min/mg protein; n = 3). To test whether organic anion transport is coupled to HCO3- extrusion, we compared the rates of taurocholate-dependent HCO3- efflux from alkali-loaded noninduced and induced cells. Monolayers grown on glass coverslips were loaded with the pH-sensitive dye 2', 7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; intracellular pH (pHi) was measured by excitation ratio fluorometry. Noninduced and induced cells were alkalinized to an equivalent pHi ( approximately 7.7) by transient exposure to a 50 mM HCO3-, Cl--free solution. In the absence of extracellular Cl- and taurocholate, isohydric reduction of superfusate HCO3- concentration from 50 to 25 mM resulted in an insignificant change in pHi over time (dpHi/dt) in both groups. Addition of 25 microM taurocholate to the superfusate led to a rapid fall in pHi in induced (-0.037 +/- 0.011 pH units/min to pHi of 7.41 +/- 0.14) but not in noninduced (0.003 +/- 0.006 pH units/min to pHi of 7.61 +/- 0.08) cells (p < 0.03). These data indicate that oatp-mediated taurocholate transport is Na+-independent, saturable, and accompanied by HCO3- exchange. We conclude that organic anion/base exchange is an important, potentially regulatable component of oatp function. PMID:9334206

  16. Extended negative dietary cation-anion difference feeding does not negatively affect postpartum performance of multiparous dairy cows.

    PubMed

    Weich, W; Block, E; Litherland, N B

    2013-09-01

    Low postpartum blood calcium remains one of the largest constraints to postpartum feed intake, milk yield, and energy balance in transitioning dairy cows. Supplemental dietary anions decrease the dietary cation-anion difference (DCAD) and reduce the risk for postpartum hypocalcemia. Prepartum management strategies aiming to minimize social stress and diet changes have resulted in a need to explore the effects of extended exposure to a negative DCAD (>21 d) diet. Holstein and Holstein-cross dairy cows (n=60) were assigned to 1 of 3 treatments 42 d before expected calving to evaluate effects of supplying anions for 21 or 42 d during the dry period on energy status, postpartum production, and Ca homeostasis. Treatments included (1) a control diet (CON; DCAD=12 mEq/100 g of DM), (2) a 21-d negative DCAD diet (21-ND; DCAD=12 and -16 mEq/100 g of DM), and (3) a 42-d negative DCAD diet (42-ND; DCAD=-16 mEq/100 g of DM). Cows fed CON were fed positive DCAD prepartum for 42 d. Cows fed 21-ND received the positive DCAD (12 mEq/100 g of DM) diet for the first 21 d of the dry period and the anionic diet (-16 mEq/100 g of DM) from d 22 until calving. Cows fed 42-ND received the anionic diet for the entire dry period. Control and anionic diets were formulated by using 2 isonitrogenous protein mixes: (1) 97.5% soybean meal and (2) 52.8% BioChlor (Church & Dwight Co. Inc.), 45.8% soybean meal. Supplementing anions induced a mild metabolic acidosis, reducing urine pH for 21-ND and 42-ND compared with CON. Prepartum DMI was not different among treatments. Postpartum DMI was higher for 21-ND compared with CON (20.8 vs. 18.1±1.1 kg/d), and 42-ND had similar DMI compared with 21-ND. During the first 56 d of lactation 21-ND had greater average milk production compared with CON (44.8 vs. 39.2±2.1 kg/d). Average milk production by 42-ND was similar to 21-ND. Postpartum total blood Ca concentration was greater for 42-ND. Cows fed anionic diets prepartum tended to have lower lipid accumulation in the liver after calving compared with CON. These data suggest low-DCAD diets fed for 21 or 42 d during the dry period can have positive effects on postpartum DMI, Ca homeostasis, and milk production. PMID:23831094

  17. 8. VIEW OF GLOVE BOXES USED IN THE ANION EXCHANGE ...

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

    8. VIEW OF GLOVE BOXES USED IN THE ANION EXCHANGE PROCESS. THE ANION EXCHANGE PROCESS PURIFIED AND CONCENTRATED PLUTONIUM-BEARING NITRIC ACID SOLUTIONS TO MAKE THEM ACCEPTABLE AS FEED FOR CONVERSION TO METAL. (6/20/60) - Rocky Flats Plant, Plutonium Recovery & Fabrication Facility, North-central section of plant, Golden, Jefferson County, CO

  18. Resonance Raman Spectrum of the Phenanthroline Anion: Implications on Electron

    E-print Network

    Turro, Claudia

    Resonance Raman Spectrum of the Phenanthroline Anion: Implications on Electron Delocalization for this localization, the correspondence of the TR3 spectrum of the excited complex to the ground state resonance Raman (rR) spectrum of 2,2- bipyridine radical anion (bpy·-) in solution is particularly persuasive.1b,6

  19. Bimetallic anionic formyl complexes: synthesis and properties

    SciTech Connect

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

    1983-05-11

    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.

  20. Poly(phenylene)-based anion exchange membrane

    DOEpatents

    Hibbs, Michael (Albuquerque, NM); Cornelius, Christopher J. (Albuquerque, NM); Fujimoto, Cy H. (Albuquerque, NM)

    2011-02-15

    A poly(phenylene) compound of copolymers that can be prepared with either random or multiblock structures where a first polymer has a repeat unit with a structure of four sequentially connected phenyl rings with a total of 2 pendant phenyl groups and 4 pendant tolyl groups and the second polymer has a repeat unit with a structure of four sequentially connected phenyl rings with a total of 6 pendant phenyl groups. The second polymer has chemical groups attached to some of the pendant phenyl groups selected from CH.sub.3, CH.sub.2Br, and CH.sub.2N(CH.sub.3).sub.3Br groups. When at least one group is CH.sub.2N(CH.sub.3).sub.3Br, the material functions as an anion exchange membrane.

  1. Gap and stripline combined monitor

    DOEpatents

    Yin, Y.

    1986-08-19

    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.

  2. Gap and stripline combined monitor

    DOEpatents

    Yin, Yan (Palo Alto, CA)

    1986-01-01

    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.

  3. Blueberries and Metabolic Syndrome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Metabolic Syndrome is a cluster of metabolic disorders that increase the risk of cardiovascular diseases. Type 2 diabetes, elevated blood pressure, and atherogenic dyslipidemia are among the metabolic alterations that predispose the individual to several adverse cardiovascular complications. The hea...

  4. High-Affinity Anion Binding by Steroidal Squaramide Receptors**

    PubMed Central

    Edwards, Sophie J; Valkenier, Hennie; Busschaert, Nathalie; Gale, Philip A; Davis, Anthony P

    2015-01-01

    Exceptionally powerful anion receptors have been constructed by placing squaramide groups in axial positions on a steroidal framework. The steroid preorganizes the squaramide NH groups such that they can act cooperatively on a bound anion, while maintaining solubility in nonpolar media. The acidic NH groups confer higher affinities than previously-used ureas or thioureas. Binding constants exceeding 1014?m?1 have been measured for tetraethylammonium salts in chloroform by employing a variation of Cram’s extraction procedure. The receptors have also been studied as transmembrane anion carriers in unilamellar vesicles. Unusually their activities do not correlate with anion affinities, thus suggesting an upper limit for binding strength in the design of anion carriers. PMID:25690527

  5. Removal of anionic reactive dyes from water using anion exchange membranes as adsorbers.

    PubMed

    Liu, Chia-Hung; Wu, Jeng-Shiou; Chiu, Hsin-Chieh; Suen, Shing-Yi; Chu, Khim Hoong

    2007-04-01

    Two commercial anion exchange membranes, strong basic (SB6407) and weak basic (DE81), were evaluated for the removal of anionic reactive dyes, Cibacron blue 3GA (three sulfonic acid groups per dye molecule) and Cibacron red 3BA (four sulfonic acid groups per dye molecule), from water in this study. The adsorption isotherm results show that the Langmuir maximum adsorption capacities of Cibacron blue 3GA (31.5mg/cm(3) for SB6407 and 25.5mg/cm(3) for DE81) were greater than those of Cibacron red 3BA (24.5mg/cm(3) for SB6407 and 18.5mg/cm(3) for DE81). For each reactive dye, the capacity for SB6407 was higher than DE81 based on the same membrane volume. However, consideration of the number of ion exchange sites interacting with a dye molecule indicates that the DE81 results are close to the theoretical values while the SB6407 membrane had some unused binding sites. In addition, Cibacron red 3BA demonstrated faster and stronger binding with both anion exchange membranes than Cibacron blue 3GA. Both dyes could bind with strong basic SB6407 more quickly and stronger. In the batch desorption process, different desorption solutions were tested and the mixtures of salt, acid, or base in methanol solution (e.g. 1N KSCN in 60% methanol or 1N HCl in 60% methanol) achieved better performance. Finally, in the flow process with one piece of anion exchange membrane (initial dye concentration of 0.05g/L), SB6407 was found superior to DE81 in dye recovery and both membranes retained their original uptake capacities over three cycles of adsorption, washing, and desorption. PMID:17328938

  6. AT Base Pair Anions vs. (9-methyl-A)(1-methyl-T) Base Pair Anions

    SciTech Connect

    Radisic, Dunja; Bowen, Kit H.; Dabkowska, Iwona; Storoniak, Piotr; Rak, Janusz; Gutowski, Maciej S.

    2005-05-04

    The anionic base pairs of adenine and thymine, (AT)-, and 9-methyladenine and 1-methylthymine, (MAMT)-, have been investigated both theoretically and experimentally in a complementary, synergistic study. Calculations on (AT)- found that it had undergone a barrier-free proton transfer (BFPT) similar to that seen in other dimer anion systems and that its structural configuration that was neither Watson-Crick (WC) nor Hoogsteen (HS). The vertical detachment energy (VDE) of (AT)- was determined by anion photoelectron spectroscopy and found to be in agreement with the VDE value predicted by theory for the BFPT mechanism. An AT pair in DNA is structurally immobilized into the WC configuration, in part, by being bonded to the sugars of the double helix. This circumstance was mimicked by methylating the sites on both A and T where these sugars would have been tied, viz., 9-methyladenine and 1-methylthymine. Calculations found no BFPT in (MAMT)- and a resulting (MAMT)- configuration that wa s either HS or WC, with the configurations differing in stability by ca. 2 kcal/mol. The photoelectron spectrum of (MAMT)- occurred at a completely different electron binding energy than had (AT)-. Moreover, the VDE value of (MAMT)- was in agreement with that predicted by theory. The configuration of (MAMT)- and its lack of electron-induced proton transfer are inter-related. While there may be other pathways for electron-induced damage, BFPT in the WC/HS configurations of (AT)- is not feasible.

  7. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    SciTech Connect

    Moyer, Bruce a.; Bostick, Debra A.; Fowler, Christopher J.; Kang, Hyun-Ah; Ruas, Alexandre; Delmau, Laetitia H.; Haverlock, Tamara J.; Llinares, Jose M.; Hossain, Alamgir; Kang, S. O.; Bowman-James, Kristin; Shriver, James A.; Marquez, Manuel; Sessler, Jonathan L.

    2005-09-22

    The major thrust of this project led by the University of Kansas (Prof. Kristin Bowman-Jones) entails the exploration of the principles of recognition and separation of sulfate by the design, synthesis, and testing of novel sulfate extractants. A key science need for the cleanup of tank wastes at Hanford has been identified in developing methods to separate those bulk waste components that have low solubilities in borosilicate glass. Sulfate has been identified as a particularly difficult and expensive problem in that its concentration in the waste is relatively high, its solubility in glass is especially low, and it interferes with the performance of both vitrification equipment and the glass waste form. The new extractants will be synthesized by the University of Kansas and the University of Texas, Austin. Oak Ridge National Laboratory (ORNL) is subjecting the new extractants to experiments that will determine their properties and effectiveness in separating sulfate from the major competing anions in the waste, especially nitrate. Such experiments will entail primarily liquid-liquid extraction. Current efforts focus on exciting new systems in which the anion receptors act as synergists for anion exchange.

  8. Gap or GapsChallenging the Singular Definition of the Achievement Gap

    Microsoft Academic Search

    Dick M. Carpenter; Al Ramirez; Laura Severn

    2006-01-01

    For decades, researchers examined the “achievement gap” between minority and nonminority students. This singular definition of achievement gap ignores important within-group differences. This article uses National Education Longitudinal Study (NELS:88) data to examine within-group differences and compares those across Latino, African American, and White populations. Results question the singular definition of achievement gap. Given the importance of how issues are

  9. Analyzing the gender pay gap

    Microsoft Academic Search

    Francine D. Blau; Lawrence M. Kahn

    1999-01-01

    Empirical research on gender pay gaps has traditionally focused on the role of gender-specific factors, particularly gender differences in qualifications and differences in the treatment of otherwise equally qualified male and female workers (i.e., labor market discrimination). This paper explores the determinants of the gender pay gap and argues for the importance of an additional factor, wage structure, the array

  10. Color Evaporation Induced Rapidity Gaps

    E-print Network

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

    1999-08-16

    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.

  11. Energy gaps in ?-graphdiyne nanoribbons

    SciTech Connect

    Niu, X. N.; Yang, D. Z.; Si, M. S., E-mail: sims@lzu.edu.cn; Xue, D. S., E-mail: xueds@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2014-04-14

    ?-graphdiyne is a novel predicted Dirac cone material, which is similar to graphene. But the absence of a band gap significantly limits its practical applications. In order to extend this limitation, an opening of energy gap is needed. To this end, we resort to the nanoribbon structure of ?-graphdiyne. This is a conventional proposal to open up the energy gaps in nanomaterials. The results show that both the armchair and the zigzag ?-graphdiyne nanoribbons do generate energy gaps, which are width-dependent. In addition, the underlying mechanism of this opening is explored. The former is ascribed to the combination of quantum confinement and edges' effect, while the latter arises from the edge magnetic ordering. These novel nanoribbons with opening energy gaps would be potentially used in electronic devices.

  12. Electronic characterization of defects in narrow gap semiconductors

    NASA Technical Reports Server (NTRS)

    Patterson, James D.

    1994-01-01

    We use a Green's function technique to calculate the position of deep defects in narrow gap semiconductors. We consider substitutional (including antisite), vacancy, and interstitial (self and foreign) deep defects. We also use perturbation theory to look at the effect of nonparabolic bands on shallow defect energies and find nonparabolicity can increase the binding by 10 percent or so. We consider mercury cadmium telluride (MCT), mercury zinc telluride (MZT), and mercury zinc selenide (MZS). For substitutional and interstitial defects we look at the situation with and without relaxation. For substitutional impurities in MCT, MZT, and MZS, we consider x (the concentration of Cd or Zn) in the range 0.1 less than x less than 0.3 and also consider appropriate x so E(sub g) = 0.1 eV for each of the three compounds. We consider several cation site s-like deep levels and anion site p-like levels. For E(sub g) = 0.1 eV, we also consider the effects of relaxation. Similar comments apply to the interstitial deep levels whereas no relaxation is considered for the ideal vacancy model. Relaxation effects can be greater for the interstitial than the substitutional cases. Specific results are given in figures and tables and comparison to experiment is made in a limited number of cases. We find, for example, that I, Se, S, Rn, and N are possible cation site, s-like deep levels in MCT and Zn and Mg are for anion site, p-like levels (both levels for substitutional cases). The corresponding cation and anion site levels for interstitial deep defects are (Au, Ag, Hg, Cd, Cu, Zn) and (N, Ar, O, F). For the substitutional cases we have some examples of relaxation moving the levels into the band gap, whereas for the interstitial case we have examples where relaxation moves it out of the band gap. Future work involves calculating the effects of charge state interaction and seeing the effect of relaxation on vacancy levels.

  13. GAP Analysis Bulletin Number 15

    USGS Publications Warehouse

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

    2008-01-01

    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

  14. Electronic materials with a wide band gap: recent developments

    PubMed Central

    Klimm, Detlef

    2014-01-01

    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

  15. Electronic materials with a wide band gap: recent developments.

    PubMed

    Klimm, Detlef

    2014-09-01

    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

  16. Mechanisms of anion conduction by coupled glutamate transporters.

    PubMed

    Machtens, Jan-Philipp; Kortzak, Daniel; Lansche, Christine; Leinenweber, Ariane; Kilian, Petra; Begemann, Birgit; Zachariae, Ulrich; Ewers, David; de Groot, Bert L; Briones, Rodolfo; Fahlke, Christoph

    2015-01-29

    Excitatory amino acid transporters (EAATs) are essential for terminating glutamatergic synaptic transmission. They are not only coupled glutamate/Na(+)/H(+)/K(+) transporters but also function as anion-selective channels. EAAT anion channels regulate neuronal excitability, and gain-of-function mutations in these proteins result in ataxia and epilepsy. We have combined molecular dynamics simulations with fluorescence spectroscopy of the prokaryotic homolog GltPh and patch-clamp recordings of mammalian EAATs to determine how these transporters conduct anions. Whereas outward- and inward-facing GltPh conformations are nonconductive, lateral movement of the glutamate transport domain from intermediate transporter conformations results in formation of an anion-selective conduction pathway. Fluorescence quenching of inserted tryptophan residues indicated the entry of anions into this pathway, and mutations of homologous pore-forming residues had analogous effects on GltPh simulations and EAAT2/EAAT4 measurements of single-channel currents and anion/cation selectivities. These findings provide a mechanistic framework of how neurotransmitter transporters can operate as anion-selective and ligand-gated ion channels. PMID:25635461

  17. Gallium based low-interaction anions

    DOEpatents

    King, Wayne A. (Santa Fe, NM); Kubas, Gregory J. (Santa Fe, NM)

    2000-01-01

    The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

  18. Postsynaptic Deregulation in GAP-43 Heterozygous Mouse Barrel Cortex

    PubMed Central

    Kelly, Emily A.; Tremblay, Marie-Ève; McCasland, James S.

    2010-01-01

    Formation of whisker-related barrels in primary somatosensory cortex (S1) requires communication between presynaptic thalamocortical afferents (TCAs) and postsynaptic cortical neurons. GAP-43 is crucially involved in targeting TCAs to postsynaptic S1 neurons but its influence on the interactions between these 2 elements has not been explored. Here, we tested the hypothesis that reduced early expression of presynaptic GAP-43 (GAP-43 heterozygous [HZ] mice) alters postsynaptic differentiation of barrel cells. We found a transient increase in cytochrome oxidase staining between P6 and P14 in HZ animals, indicative of increased metabolic activity in barrel cortex during this time. Golgi impregnation and microtubule-associated protein 2 immunohistochemistry showed anomalous dendritic patterning in GAP-43 HZ cortex at P5, with altered dendritic length and branching and abnormal retention of dendrites that extend into developing septa. This deficiency was no longer apparent at P7, suggesting partial recovery of dendritic pruning processes. Finally, we showed early defects in synaptogenesis from P4 to P5 with increased colocalization of NR1 and GluR1 staining in HZ mice. By P7, this colocalization had normalized to wild type levels. Taken together, our findings suggest abnormal postsynaptic differentiation in GAP-43 HZ cortex during early barrel development, followed by adaptive compensation and partial phenotypic rescue. PMID:19915093

  19. Pneumatic gap sensor and method

    DOEpatents

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

    1992-03-03

    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.

  20. In situ gelling properties of anionic thiomers.

    PubMed

    Hintzen, Fabian; Laffleur, Flavia; Sakloetsakun, Duangkamon; Leithner, Katharina; Bernkop-Schnürch, Andreas

    2012-12-01

    The aim of this study was to investigate in situ crosslinking systems of anionic thiolated polymers. In order to accelerate the increase in dynamic viscosity of thiolated polymers (thiomers), they were combined with hydrogen peroxide, carbamide peroxide and ammonium persulfate. Thiomers (pectin-cysteine (Pec-Cys), sodium carboxymethylcellulose-cysteine (NaCMC-Cys) and poly(acrylic acid)-cysteine (PAA-Cys)) were synthesized via amide bond formation between the carboxylic acid group of polymers and the primary amino group of l-cysteine. The rheological properties of 1% (m/v) thiomer solutions with oxidizing agents were compared by oscillatory measurements over time (120?min). Pec-Cys and NaCMC-Cys with hydrogen and carbamide peroxide showed a sol-gel phase transition within a few minutes and scored up to 13,000-fold increase in dynamic viscosity. Furthermore, only thiomers exhibiting a polysaccharide backbone (Pec-Cys and NaCMC-Cys) showed a significant increase in viscosity (p?

  1. Astroglial Metabolic Networks Sustain Hippocampal Synaptic Transmission

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    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.

  2. 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...

  3. ELECTROACTIVE MATERIALS FOR ANION SEPARATION-TECHNETIUM FROM NITRATE

    EPA Science Inventory

    The proposed research will provide the basis for using electroactive ion exchange materials to remove anionic contaminants from HLW wastes and process streams. An ion exchange process using electroactive materials sorbs contaminants selectively and then expels (elutes) them elec...

  4. Nitrate Anion Exchange in Pu-238 Aqueous Scrap Recovery Operations

    SciTech Connect

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

    1999-01-31

    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.

  5. Anionic Homopolymers Efficiently Target Zerovalent Iron Particles to

    E-print Network

    be estimated. The anionic polyelectrolytes tested (polyacrylate, carboxymethylcellulose, alginate, asexpectedfromearlierstudies.However,ironparticlesmodified with the two moderately hydrophobic polymers (carboxym of collector grains was found with the more polar polymers (metasilicate and alginate). The trend in sticking

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

    SciTech Connect

    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

    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.

  7. Plenary 1 – Gaps in Oncology

    Cancer.gov

    The first plenary of the EPEC-O (Education in Palliative and End-of-Life Care for Oncology) Self-Study Original Version provides background for the curriculum and identifies gaps in current and desired comprehensive cancer care.

  8. Rapidity Gap Results from Tevatron

    SciTech Connect

    K. Terashi

    1999-04-08

    Results of rapidity gap physics in the CDF and DO Collaborations are presented. In particular, hard diffraction (diffractive dijet and heavy flavor quark production, dijet production in Double Pomeron Exchange) and color-singlet exchange are described.

  9. The design of luminescent sensors for anions and ionisable analytes

    Microsoft Academic Search

    Luigi Fabbrizzi; Maurizio Licchelli; Giuliano Rabaioli; Angelo Taglietti

    2000-01-01

    A molecular luminescent sensor for anions can be built through a modular approach, i.e. by covalently linking an appropriate photoactive fragment to the receptor displaying a satisfactory affinity towards the desired substrate. Following the receptor-anion interaction, an intercomponent process must take place, e.g. an electron transfer (eT) or an energy transfer (ET) process, that distinctly modifies the emission of the

  10. Photo-multidetachment and Fragmentation of C60 Anions

    NASA Astrophysics Data System (ADS)

    Bilodeau, R. C.; Gibson, N. D.; Walter, C. W.; Esteves, D. A.; Phaneuf, R. A.; Schippers, S.; Müller, A.; Aguilar, A.; Hoener, M.; Rost, J. M.; Berrah, N.

    2012-11-01

    Absolute single-photon multi-electron ionization and fragmentation cross sections for C-60 ions are measured for the first time. It is determined that the excess electron in the anion causes a significant increase in cross section and an overall energy scaling, but otherwise has little effect on the observed structure. Appearance energies (apparent thresholds) of the fragmentation products are also observed to be significantly lower for the anion, as compared to the neutral molecule.

  11. Characterization of a Saturated and Flexible Aliphatic Polyol Anion Receptor

    SciTech Connect

    Shokri, Alireza; Schmidt, Jacob C.; Wang, Xue B.; Kass, Steven R.

    2012-10-17

    Nature employs flexible molecules to bind anions in a variety of physiologically important processes whereas supramolecular chemists have been designing rigid substrates that minimize or eliminate intramolecular hydrogen bond interactions to carry out anion recogni-tion. Herein, the association of a flexible polyhydroxy alkane with chloride ion is described and the bound re-ceptor is characterized by infrared and photoelectron spectroscopy in the gas phase, computations, and its bind-ing constant as a function of temperature in acetonitrile.

  12. Gas-Grain Models for Interstellar Anion Chemistry

    NASA Technical Reports Server (NTRS)

    Cordiner, M. A.; Charnely, S. B.

    2012-01-01

    Long-chain hydrocarbon anions C(sub n) H(-) (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 H2) approx > / cubic cm). 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 C6H(-) 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 C6O, C7O, HC6O, and HC7O, the abundances of which depend on the assumed branching ratios for associative electron detachment

  13. Anions of Transition Metal Cluster/Benzene Complexes

    NASA Astrophysics Data System (ADS)

    Bowen, Kit

    2002-03-01

    We report the anion photoelectron spectra of several transition metal atom or cluster/benzene anionic complexes. These species can serve as preliminary models for assessing the interaction between transition metal atoms/clusters and graphitic surfaces, especially in regard to how this interaction affects the magnetic moments of transition metal atoms or clusters. We are guided in this work by the calculations of Jena, Khanna, and Rao.

  14. Ion displacement following the adsorption of anionic macromolecules on hydroxyapatite

    Microsoft Academic Search

    E. I. F. Pearce

    1981-01-01

    Summary  Certain small anionic molecules displace phosphate ions from the hydroxyapatite crystal hydration layer on adsorption. This\\u000a follows the interaction of negatively charged groups with calcium ions in the crystal surface. The present study examines\\u000a ion-exchange processes occurring during the adsorption of anionic macromolecules and attempts to determine the role of coulombic\\u000a forces in the process. Various natural and synthetic polyanionic

  15. Total synthesis of (+)-cassaine utilizing an anionic polycyclization strategy.

    PubMed

    Ravindar, Kontham; Caron, Pierre-Yves; Deslongchamps, Pierre

    2013-12-20

    A stereoselective total synthesis of (+)-cassaine (1) via an anionic polycyclization methodology is described. Commercially available (+)-carvone (5), the only chiral source, was used to fix the entire stereochemistry of the natural product. Anionic polycyclization of a new substituted 2-(methoxycarbonyl)cyclohex-2-en-1-one (4) with known 1-phenylysulfinyl-3-penten-2-one (3) provided the versatile tricycle (2) with requisite stereochemistry. A sequence of functional group manipulations of tricycle (2) furnished the natural product 1. PMID:24295200

  16. Closing the Prescription Drug Coverage Gap

    MedlinePLUS

    ... participate in this program. How is coverage for generic drugs changing in the coverage gap? In 2015, Medicare ... coverage gap You’ll pay this percentage for generic drugs in the coverage gap 2015 45% 65% 2016 ...

  17. Genome-scale models of bacterial metabolism: reconstruction and applications

    PubMed Central

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

    2009-01-01

    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

  18. Colour Reconnections and Rapidity Gaps

    E-print Network

    Leif Lonnblad

    1995-12-20

    The success of recently proposed models for describing rapidity-gap events in DIS at HERA, in terms additional colour exchange between the struck system and the proton remnant in boson-gluon fusion events, are found to rely heavily on the absence or artificial suppression of perturbative gluon emission in the forward region. A model without such suppression is presented, which cannot describe the rapidity-gap events without a pomeron-inspired mechanism.

  19. Anion size modulates salt taste in rats.

    PubMed

    Breza, Joseph M; Contreras, Robert J

    2012-03-01

    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 NH(4)Cl, 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

  20. Anion size modulates salt taste in rats

    PubMed Central

    Breza, Joseph M.

    2012-01-01

    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

  1. Annular Anionic Lipids Stabilize the Integrin ?IIb?3 Transmembrane Complex.

    PubMed

    Schmidt, Thomas; Suk, Jae-Eun; Ye, Feng; Situ, Alan J; Mazumder, Parichita; Ginsberg, Mark H; Ulmer, Tobias S

    2015-03-27

    Cationic membrane-proximal amino acids determine the topology of membrane proteins by interacting with anionic lipids that are restricted to the intracellular membrane leaflet. This mechanism implies that anionic lipids interfere with electrostatic interactions of membrane proteins. The integrin ?IIb?3 transmembrane (TM) complex is stabilized by a membrane-proximal ?IIb(Arg(995))-?3(Asp(723)) interaction; here, we examine the influence of anionic lipids on this complex. Anionic lipids compete for ?IIb(Arg(995)) contacts with ?3(Asp(723)) but paradoxically do not diminish the contribution of ?IIb(Arg(995))-?3(Asp(723)) to TM complex stability. Overall, anionic lipids in annular positions stabilize the ?IIb?3 TM complex by up to 0.50 ± 0.02 kcal/mol relative to zwitterionic lipids in a headgroup structure-dependent manner. Comparatively, integrin receptor activation requires TM complex destabilization of 1.5 ± 0.2 kcal/mol, revealing a sizeable influence of lipid composition on TM complex stability. We implicate changes in lipid headgroup accessibility to small molecules (physical membrane characteristics) and specific but dynamic protein-lipid contacts in this TM helix-helix stabilization. Thus, anionic lipids in ubiquitous annular positions can benefit the stability of membrane proteins while leaving membrane-proximal electrostatic interactions intact. PMID:25632962

  2. The gecko visual pigment: the anion hypsochromic effect.

    PubMed

    Crescitelli, F; Karvaly, B

    1991-01-01

    The 521-pigment in the retina of the Tokay gecko (Gekko gekko) readily responds to particular physical and chemical changes in its environment. When solubilized in chloride deficient state the addition of Class I anions (Cl-, Br-) induces a bathochromic shift of the absorption spectrum. Class II anions (NO3-, IO3-, N3-, OCN-, SCN-, SeCN-, N(CN)2-), which exhibit ambidental properties, cause an hypsochromic shift. Class III anions (F-, I-, NO2-, CN-, AsO3-, SO2(4-), S2O2(3-) have no spectral effect on the 521-pigment. Cations appear to have no influence on the pigment absorption and Class I anions prevent or reverse the hypsochromic shift caused by Class II anions. It is suggested that the spectral displacements reflect specific changes in the opsin conformation, which alter the immediate (dipolar) environment of the retinal chromophore. The protein conformation seems to promote excited-state processes most in the native 521-pigment state and least in the presence of Class II anions. This in turn suggests that the photosensitivity of the 521-pigment is controlled by the excited rather than by the ground-state properties of the pigment. PMID:1858325

  3. Counterion-mediated pattern formation in membranes containing anionic lipids

    PubMed Central

    Slochower, David R.; Wang, Yu-Hsiu; Tourdot, Richard W.; Radhakrishnan, Ravi; Janmey, Paul A.

    2014-01-01

    Most lipid components of cell membranes are either neutral, like cholesterol, or zwitterionic, like phosphatidylcholine and sphingomyelin. Very few lipids, such as sphingosine, are cationic at physiological pH. These generally interact only transiently with the lipid bilayer, and their synthetic analogs are often designed to destabilize the membrane for drug or DNA delivery. However, anionic lipids are common in both eukaryotic and prokaryotic cell membranes. The net charge per anionic phospholipid ranges from ?1 for the most abundant anionic lipids such has phosphatidylserine, to near ?7 for phosphatidylinositol 3,4,5 trisphosphate, although the effective charge depends on many environmental factors. Anionic phospholipids and other negatively charged lipids such as lipopolysaccharides are not randomly distributed in the lipid bilayer, but are highly restricted to specific leaflets of the bilayer and to regions near transmembrane proteins or other organized structures within the plane of the membrane. This review highlights some recent evidence that counterions, in the form of monovalent or divalent metal ions, polyamines, or cationic protein domains, have a large influence of the lateral distribution of anionic lipids within the membrane, and that lateral demixing of anionic lipids has effects on membrane curvature and protein function that are important for biological control. PMID:24556233

  4. Prestin's Anion Transport and Voltage-Sensing Capabilities Are Independent

    PubMed Central

    Bai, Jun-Ping; Surguchev, Alexei; Montoya, Simone; Aronson, Peter S.; Santos-Sacchi, Joseph; Navaratnam, Dhasakumar

    2009-01-01

    Abstract The integral membrane protein prestin, a member of the SLC26 anion transporter family, is responsible for the voltage-driven electromotility of mammalian outer hair cells. It was argued that the evolution of prestin's motor function required a loss of the protein's transport capabilities. Instead, it was proposed that prestin manages only an abortive hemicycle that results in the trapped anion acting as a voltage sensor, to generate the motor's signature gating charge movement or nonlinear capacitance. We demonstrate, using classical radioactive anion ([14C]formate and [14C]oxalate) uptake studies, that in contrast to previous observations, prestin is able to transport anions. The prestin-dependent uptake of both these anions was twofold that of cells transfected with vector alone, and comparable to SLC26a6, prestin's closest phylogenetic relative. Furthermore, we identify a potential chloride-binding site in which the mutations of two residues (P328A and L326A) preserve nonlinear capacitance, yet negate anion transport. Finally, we distinguish 12 charged residues out of 22, residing within prestin's transmembrane regions, that contribute to unitary charge movement, i.e., voltage sensing. These data redefine our mechanistic concept of prestin. PMID:19383462

  5. In vivo tissue-wide synchronization of mitochondrial metabolic oscillations

    PubMed Central

    Porat-Shliom, Natalie; Chen, Yun; Tora, Muhibullah; Shitara, Akiko; Masedunskas, Andrius; Weigert, Roberto

    2014-01-01

    Summary Little is known about the spatio-temporal coordination of mitochondrial metabolism in multicellular organisms in situ. Using intravital microscopy in live animals, we here report that mitochondrial metabolism undergoes rapid and periodic oscillations under basal conditions. Notably, mitochondria in vivo behave as a network of functionally coupled oscillators, which maintain a high level of coordination throughout the tissue via the activity of gap junctions. These findings reveal a unique aspect of the relationship between tissue architecture and self-organization of mitochondrial metabolism in vivo. PMID:25373899

  6. Verb gapping: An action-gap compatibility study.

    PubMed

    Claus, Berry

    2015-03-01

    This study addresses the processing of verb-gapping sentences, e.g., John closes a juice bottle and Jim [ ] a lemonade bottle. The goal was to explore if there would be an interaction between language comprehension and motor action not only for overt action verbs but also for gapped verbs. Participants read gapping sentences that either described clockwise or counter-clockwise manual rotations (e.g., closes vs. opens a juice bottle). Adopting a paradigm developed by Zwaan and Taylor (2006), sentence presentation was frame-by-frame. Participants proceeded from frame to frame by turning a knob either clockwise or counter clockwise. Analyses of the frame reading-times yielded a significant effect of compatibility between the linguistically conveyed action and the knob turning for the overt-verb (e.g., closes/opens a juice bottle) as well as for the gapped-verb frame (e.g., a lemonade bottle) - with longer reading times in the match condition than in the mismatch condition - but not for any of the other frames (e.g., and Jim). The results are promising in providing novel evidence for the real-time reactivation of gapped verbs and in suggesting that action simulation is not bound to the processing of overt verbs. PMID:25103783

  7. Paying Attention to Dietary Cation-Anion Balance Can Mean More Milk and Fewer Metabolic Problems

    E-print Network

    Liskiewicz, Maciej

    +50 Sodium sesquicarbonate, grams 130 200 240 Potassium carbonate, grams 50 170 260 Sodium, % 0.45 0 for lactating cows in cooler weather. Sodium sesquicarbonate (a form of sodium bi- carbonate) and potassium carbonate were used in this study to supply sodium and potassium. Certainly the +50 DCAD level was excessive

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    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.

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

    E-print Network

    Rogers, Simon

    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

  10. DISCOVERY OF INTERSTELLAR ANIONS IN CEPHEUS AND AURIGA

    SciTech Connect

    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

    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.

  11. Discovery of Interstellar Anions in Cepheus and Auriga

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

  12. The role of catalyst precursor anions in coal gasification

    SciTech Connect

    Abotsi, G.M.K.

    1992-08-28

    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 North Dakota lignite (PSOC 1482) and its demineralized derivative with calcium or potassium catalyst precursors containing acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sub 3}{sup {minus}}), sulfate (SO{sub 4}{sup 2{minus}}), and carbonate (CO{sub 3}{sup 2{minus}}) anions. Catalyst loading will be conducted under well-controlled conditions of solution pH and ionic strength. In the last quarter, the surface charge properties of the coal was determined as a function of acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sup 3}{sup {minus}}), carbonate (CO{sub 3}{sup 2{minus}}) or sulfate (SO{sub 4}{sup 2{minus}})concentration using the respective potassium salts of these anions. In general, low anion concentrations (10{sup {minus}3} or 10{sup {minus}2} mol/L) had little effect on the zeta potentials of the coals. However, the surface charge densities of the coal become less negative at 10-1 mol/L of the nitrate, carbonate or sulfate anions. These trends suggest that the surface charge density of the coal is controlled by the adsorption of potassium ions (K{sup +}) onto the coal particles. The net negative charge on the coal panicles creates a repulsive force between the anions and the coal surface and prevents the anions from exerting any significant effect on the coal's electrokinetic properties.

  13. Palladium catalysed tandem cyclisation–anion capture. Part 8: Cascade hydrostannylation—cyclisation–anion capture and cascade hydroboration—cyclisation–anion capture on solid phase

    Microsoft Academic Search

    Ronald Grigg; William S MacLachlan; David T MacPherson; Visuvanathar Sridharan; Selvaratnam Suganthan

    2001-01-01

    Up to four bonds and five stereocentres are created, in five component processes (five point diversity), utilising resin bound aryl iodides by hydroboration or hydrostannylation of alkynes, followed by cyclisation–anion capture involving Suzuki or Stille reactions. Three small libraries were prepared to validate the chemistry.

  14. Field induced gap infrared detector

    NASA Technical Reports Server (NTRS)

    Elliott, C. Thomas (inventor)

    1990-01-01

    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.

  15. Explaining the Gender Wealth Gap

    PubMed Central

    Ruel, Erin; Hauser, Robert M.

    2013-01-01

    To assess and explain the United States’ gender wealth gap, we use the Wisconsin Longitudinal Study to examine wealth accumulated by a single cohort over 50 years by gender, by marital status, and limited to the respondents who are their family’s best financial reporters. We find large gender wealth gaps between currently married men and women, and never-married men and women. The never-married accumulate less wealth than the currently married, and there is a marital disruption cost to wealth accumulation. The status-attainment model shows the most power in explaining gender wealth gaps between these groups explaining about one-third to one-half of the gap, followed by the human-capital explanation. In other words, a lifetime of lower earnings for women translates into greatly reduced wealth accumulation. A gender wealth gap remains between married men and women after controlling for the full model that we speculate may be related to gender differences in investment strategies and selection effects. PMID:23264038

  16. Crop yield gaps in Cameroon.

    PubMed

    Yengoh, Genesis T; Ardö, Jonas

    2014-03-01

    Although food crop yields per hectare have generally been increasing in Cameroon since 1961, the food price crisis of 2008 and the ensuing social unrest and fatalities raised concerns about the country's ability to meet the food needs of its population. This study examines the country's potential for increasing crop yields and food production to meet this food security challenge. Fuzzy set theory is used to develop a biophysical spatial suitability model for different crops, which in turn is employed to ascertain whether crop production is carried out in biophysically suited areas. We use linear regression to examine the trend of yield development over the last half century. On the basis of yield data from experimental stations and farmers' fields we assess the yield gap for major food crops. We find that yields have generally been increasing over the last half century and that agricultural policies can have significant effects on them. To a large extent, food crops are cultivated in areas that are biophysically suited for their cultivation, meaning that the yield gap is not a problem of biophysical suitability. Notwithstanding, there are significantly large yield gaps between actual yields on farmers' farms and maximum attainable yields from research stations. We conclude that agronomy and policies are likely to be the reasons for these large yield gaps. A key challenge to be addressed in closing the yield gaps is that of replenishing and properly managing soil nutrients. PMID:23925855

  17. Metabolism of Bifidobacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genus Bifidobacterium possesses a unique fructose-6-phosphate phosphoketolase pathway employed to ferment carbohydrates. Much metabolic research on bifidobacteria has focused on oligosaccharide metabolism as these carbohydrate polymers are available in their otherwise nutrient-limited habitats....

  18. Mechanism of adsorption of hard and soft metal ions to Saccharomyces cerevisiae and influence of hard and soft anions.

    PubMed Central

    Avery, S V; Tobin, J M

    1993-01-01

    The applicability of the hard-and-soft principle of acids and bases in predicting metal adsorption characteristics in a biological context was investigated for metabolism-independent uptake of the metal ions Sr2+, Mn2+, Zn2+, Cu2+, Cd2+, and Tl+ by Saccharomyces cerevisiae. Metal adsorption increased with external metal concentration (5 to 50 microM), although some saturation of uptake of the harder ions examined, Sr2+, Mn2+, and Zn2+, was evident at the higher metal concentrations. Cation displacement experiments indicated that, with the exception of Tl+, relative covalent bonding (H+ displacement) of the metals was greater at low metal concentrations, while weaker electrostatic interactions (Mg2+ plus Ca2+ displacement) became increasingly important at higher concentrations. These results were correlated with curved Scatchard and reciprocal Langmuir plots of metal uptake data. Saturation of covalent binding sites was most marked for the hard metals, and consequently, although no relationship between metal hardness and ionic/covalent bonding ratios was evident at 10 microM metal, at 50 microM the ratio was generally higher for harder metals. Increasing inhibition of metal uptake at increasing external anion concentrations was partially attributed to the formation of metal-anion complexes. Inhibitory effects of the hard anion SO42(-) were most marked for uptake of the hard metals Sr2+ and Mn2+, whereas greater relative effects on adsorption of the softer cations Cu2+ and Cd2+ were correlated with complexation by the soft anion S2O32(-). Inhibition of uptake of the borderline metal Zn2+ by SO42(-) and that by S2O32(-) were approximately equal.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8215359

  19. ABORT GAP CLEANING IN RHIC.

    SciTech Connect

    DREES,A.; AHRENS,L.; III FLILLER,R.; GASSNER,D.; MCINTYRE,G.T.; MICHNOFF,R.; TRBOJEVIC,D.

    2002-06-03

    During the RHIC Au-run in 2001 the 200 MHz storage cavity system was used for the first time. The rebucketing procedure caused significant beam debunching in addition to amplifying debunching due to other mechanisms. At the end of a four hour store, debunched beam could account for approximately 30%-40% of the total beam intensity. Some of it will be in the abort gap. In order to minimize the risk of magnet quenching due to uncontrolled beam losses at the time of a beam dump, a combination of a fast transverse kicker and copper collimators were used to clean the abort gap. This report gives an overview of the gap cleaning procedure and the achieved performance.

  20. Virtual gap dielectric wall accelerator

    DOEpatents

    Caporaso, George James; Chen, Yu-Jiuan; Nelson, Scott; Sullivan, Jim; Hawkins, Steven A

    2013-11-05

    A virtual, moving accelerating gap is formed along an insulating tube in a dielectric wall accelerator (DWA) by locally controlling the conductivity of the tube. Localized voltage concentration is thus achieved by sequential activation of a variable resistive tube or stalk down the axis of an inductive voltage adder, producing a "virtual" traveling wave along the tube. The tube conductivity can be controlled at a desired location, which can be moved at a desired rate, by light illumination, or by photoconductive switches, or by other means. As a result, an impressed voltage along the tube appears predominantly over a local region, the virtual gap. By making the length of the tube large in comparison to the virtual gap length, the effective gain of the accelerator can be made very large.

  1. Hard diffraction and rapidity gaps

    SciTech Connect

    Brandt, A.

    1995-09-01

    The field of hard diffraction, which studies events with a rapidity gap and a hard scattering, has expanded dramatically recently. A review of new results from CDF, D{O}, H1 and ZEUS will be given. These results include diffractive jet production, deep-inelastic scattering in large rapidity gap events, rapidity gaps between high transverse energy jets, and a search for diffractive W-boson production. The combination of these results gives new insight into the exchanged object, believed to be the pomeron. The results axe consistent with factorization and with a hard pomeron that contains both quarks and gluons. There is also evidence for the exchange of a strongly interacting color singlet in high momentum transfer (36 < {vert_bar}t{vert_bar} < 1000 GeV{sup 2}) events.

  2. On thermal radiation across nanoscale gaps

    NASA Astrophysics Data System (ADS)

    Budaev, Bair V.; Bogy, David B.

    2015-02-01

    It is shown that the analysis of radiative heat transport across a nanoscale gap cannot ignore the correlation between radiations from the different sides of the gap. This correlation can be neglected in two cases: when the gap is considerably wider than the dominant wavelength of radiation and when the temperatures on different sides of the gap are equal.

  3. Closing the Salary Gap Noreen Rossi

    E-print Network

    Finley Jr., Russell L.

    · Clinicians #12;Even among top physicians, the gender wage gap remains. Researchers from Univ of MichiganClosing the Salary Gap Noreen Rossi Dawn Misra #12;Overview · Evidence of salary gap for women · What contributes to the gap? ­ Institutional barriers ­ Women's own practices · Sharing stories · Best

  4. Gap survival probability and rescattering at HERA

    E-print Network

    : · In diffraction, rapidity gaps may be destroyed by secondary particles generated by rescattering processes between selection Diffractive events: `Large rapidity gap' method: · Exchange of colourless IP: lack of particle states, suppressing the large rapidity gap: suppression `rapidity gap survival probability' · Models

  5. Reversible Intercalation of Fluoride-Anion Receptor Complexes in Graphite

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Anderson, Bryan D.; Tracy, Joseph B.

    2014-10-01

    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.

  7. Oxidation of silicon surface with atomic oxygen radical anions

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

    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.

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

    PubMed

    Arunachalam, M; Ghosh, Pradyut

    2010-02-01

    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

  9. knowledge gap Filling Knowledge Gaps in a BroadCoverage

    E-print Network

    Knight, Kevin

    Kevin Knight, Ishwar Chander, Matthew Haines, Vasileios Hatzivassiloglou, Eduard Hovy, Masayo Iida. This pa­ per describes how we can fill various KBMT knowl­ edge gaps, often using robust statistical'' and has a place for each piece of new knowl­ edge, whether it be lexical, grammatical, or conceptual

  10. Want to Close the Achievement Gap? Close the Teaching Gap

    ERIC Educational Resources Information Center

    Darling-Hammond, Linda

    2015-01-01

    For years now, educators have looked to international tests as a yardstick to measure how well students from the United States are learning compared with their peers. The answer has been: not so well. The United States has been falling further behind other nations and has struggled with a large achievement gap. Federal policy under No Child Left…

  11. Racial Gap in Teachers’ Perceptions of the Achievement Gap

    Microsoft Academic Search

    Jeffrey Uhlenberg; Kathleen M. Brown

    2002-01-01

    Why does the achievement gap exist, and what should we do about it? Ogbu and Simons suggested that urban minority parents “hold teachers and schools, rather than their children, responsible for poor academic performance.” Other adults focus on the children and families, commenting on such things as poverty and lack of parental concern. And then there are the students who

  12. Folk Belief Theory, the Rigor Gap, and the Achievement Gap

    ERIC Educational Resources Information Center

    Torff, Bruce

    2014-01-01

    Folk belief theory is suggested as a primary cause for the persistence of the achievement gap. In this research-supported theory, culturally specified folk beliefs about learning and teaching prompt educators to direct more rigorous curriculum to high-advantage students but not to low-advantage students, resulting in impoverished pedagogy in…

  13. Periodic Manifolds with Spectral Gaps

    E-print Network

    Olaf Post

    2002-07-14

    We investigate spectral properties of the Laplace operator on a class of non-compact Riemannian manifolds. For a given number $N$ we construct periodic (i.e. covering) manifolds such that the essential spectrum of the corresponding Laplacian has at least $N$ open gaps. We use two different methods. First, we construct a periodic manifold starting from an infinite number of copies of a compact manifold, connected by small cylinders. In the second construction we begin with a periodic manifold which will be conformally deformed. In both constructions, a decoupling of the different period cells is responsible for the gaps.

  14. Epigenetics and cancer metabolism.

    PubMed

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

    2015-01-28

    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

  15. Monovalent Ion Selectivity Sequences of the Rat Connexin43 Gap Junction Channel

    PubMed Central

    Wang, Hong-Zhan; Veenstra, Richard D.

    1997-01-01

    The relative permeability sequences of the rat connexin 43 (rCx43) gap junction channel to seven cations and chloride were examined by double whole cell patch clamp recording of single gap junction channel currents in rCx43 transfected neuroblastoma 2A (N2A) cell pairs. The measured maximal single channel slope conductances (?j, in pS) of the junctional current-voltage relationships in 115 mM XCl were RbCl (103) ? CsCl (102) > KCl (97) > NaCl (79) ? LiCl (78) > TMACl (65) > TEACl (53) and for 115 mM KY were KBr (105) > KCl (97) > Kacetate (77) > Kglutamate (61). The single channel conductance-aqueous mobility relationships for the test cations and anions were linear. However, the predicted minimum anionic and cationic conductances of these plots did not accurately predict the rCx43 channel conductance in 115 mM KCl. Instead, the conductance of the rCx43 channel in 115 mM KCl was accurately predicted from cationic and anionic conductance-mobility plots by applying a mobility scaling factor Dx/Do, which depends upon the relative radii of the permeant ions to an estimated pore radius. Relative permeabilities were determined for all of the monovalent cations and anions tested from asymmetric salt reversal potential measurements and the Goldman-Hodgkin-Katz voltage equation. These experiments estimate the relative chloride to potassium permeability to be 0.13. The relationship between the relative cation permeability and hydrated radius was modeled using the hydrodynamic equation assuming a pore radius of 6.3 ± 0.4 ?. Our data quantitatively demonstrate that the rCx43 gap junction channel is permeable to monovalent atomic and organic cations and anions and the relative permeability sequences are consistent with an Eisenman sequence II or I, respectively. These predictions about the rCx43 channel pore provide a useful basis for future investigations into the structural determinants of the conductance and permeability properties of the connexin channel pore. PMID:9101407

  16. Reactivity of ambident anions in the gas phase

    NASA Astrophysics Data System (ADS)

    Freriks, Ivo. L.

    1992-12-01

    Ambident anions are negative ions in which several reactive centra are coupled via resonance. When these ions react, there is a competition possible between the reaction channels via each of these reactive centra. A systematic study on the reactivity of several ambident anions in a Fourier transform ion cyclotron resonance mass spectrometer is described in the thesis. Via probe reactions it is shown that a gas-phase ion/molecule reaction between an ambident anion and an unsaturated polyfluorocarbon compound enables a distinction between the competing reaction channels mentioned. The obtained product distributions can be interpreted using simple perturbation theory. In chapter one of the thesis several models and concepts (such as hard and soft acids and bases, HSAB, perturbation theory and the Allopolarisierungs-Prinzip) are described which have been used previously to explain the reactivity of ambident ions in solution.

  17. Cell wall bound anionic peroxidases from asparagus byproducts.

    PubMed

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

    2014-10-01

    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

  18. Alfred Werner revisited: the coordination chemistry of anions.

    PubMed

    Bowman-James, Kristin

    2005-08-01

    A series of macrocyclic receptors were designed to probe the influence of four factors, hydrogen bonding, charge, dimensionality, and topology, on anion binding. Monocyclic and bicyclic polyammonium and polyamide receptors were synthesized from either 2,2'-diaminodiethylamine derivatives (dien) or 2,2',2''-aminoethylamine (tren) building blocks, plus aromatic or heterocyclic spacers. Supramolecular complexes of these hosts with three simple anion topologies were probed: spherical (halides), trigonal planar (nitrate), and tetrahedral (sulfate). Results indicate a number of corollaries with transition-metal coordination chemistry in terms of binding concepts such as the chelate effect and dual valencies, as well as geometries for anion complexes that are strikingly similar to those observed in transition-metal coordination chemistry. PMID:16104690

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

    PubMed

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

    2008-03-01

    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

  20. Analysis of anions in geological brines using ion chromatography

    SciTech Connect

    Merrill, R.M.

    1985-03-01

    Ion chromatographic procedures for the determination of the anions bromide, sulfate, nitrite, nitrate, phosphate, and iodide in brine samples have been developed and are described. The techniques have been applied to the analysis of natural brines, and geologic evaporites. Sample matrices varied over a range from 15,000 mg/L to 200,000 mg/L total halogens, nearly all of which is chloride. The analyzed anion concentrations ranged from less than 5 mg/L in the cases of nitrite, nitrate, and phosphate, to 20,000 mg/L in the case of sulfate. A technique for suppressing chloride and sulfate ions to facilitate the analysis of lower concentration anions is presented. Analysis times are typically less than 20 minutes for each procedure and the ion chromatographic results compare well with those obtained using more time consuming classical chemical analyses. 10 references, 14 figures.

  1. Autodetachment spectroscopy of a molecular anion using a diode laser

    SciTech Connect

    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

    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.

  2. Solubility and transport of cationic and anionic patterned nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    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.

  3. Sustained metabolic scope.

    PubMed Central

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

    1990-01-01

    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

  4. Multiple input electrode gap controller

    DOEpatents

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

    1999-07-27

    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.

  5. The Widening Income Achievement Gap

    ERIC Educational Resources Information Center

    Reardon, Sean F.

    2013-01-01

    Has the academic achievement gap between high-income and low-income students changed over the last few decades? If so, why? And what can schools do about it? Researcher Sean F. Reardon conducted a comprehensive analysis of research to answer these questions and came up with some striking findings. In this article, he shows that income-related…

  6. The Racial Academic Achievement Gap

    ERIC Educational Resources Information Center

    Green, Toneka M.

    2008-01-01

    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…

  7. Large gap magnetic suspension system

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  8. Multiplicity distributions and rapidity gaps

    Microsoft Academic Search

    Jon Pumplin

    1994-01-01

    We examine the phenomenology of particle multiplicity distributions, with special emphasis on the low multiplicities that are a background to the study of rapidity gaps. In particular, we analyze the multiplicity distribution in a rapidity interval between two jets, using the herwig QCD simulation with some necessary modifications. The distribution is not of the ``negative binomial'' form, and displays an

  9. Mixed anion materials and compounds for novel proton conducting membranes

    DOEpatents

    Poling, Steven Andrew; Nelson, Carly R.; Martin, Steve W.

    2006-09-05

    The present invention provides new amorphous or partially crystalline mixed anion chalcogenide compounds for use in proton exchange membranes which are able to operate over a wide variety of temperature ranges, including in the intermediate temperature range of about 100 .degree. C. to 300.degree. C., and new uses for crystalline mixed anion chalcogenide compounds in such proton exchange membranes. In one embodiment, the proton conductivity of the compounds is between about 10-8 S/cm and 10-1 S/cm within a temperature range of between about -60 and 300.degree. C. and a relative humidity of less than about 12%.

  10. Characteristics of anionic metal species biosorption with waste crab shells

    Microsoft Academic Search

    Hui Niu; Bohumil Volesky

    2003-01-01

    Anionic metal complexes are very effectively bound by biomass types containing an abundance of amine groups. Readily available chitinous materials such as acid-washed Ucides shells (AWUS) sorbed well anionic gold-cyanide (Au(CN)2?), selenate (SeO42?), chromate (CrO42?) and vanadate (VO43?) at low pH. Equilibrium biosorption uptakes by AWUS were up to 0.17 mmol Au\\/g AWUS (pH 3.4), 0.15 mmol Se\\/g (pH 3.0),

  11. Photoelectron spectroscopy of boron aluminum hydride cluster anions

    SciTech Connect

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H., E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Li, Xiang [Center for Space Science and Technology, University of Maryland–Baltimore County, Baltimore, Maryland 21250 (United States)] [Center for Space Science and Technology, University of Maryland–Baltimore County, Baltimore, Maryland 21250 (United States); Kiran, Boggavarapu, E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana 70609 (United States)] [Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana 70609 (United States); Kandalam, Anil K. [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)] [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)

    2014-04-28

    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, B{sub x}Al{sub y}H{sub z}{sup ?}, 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.

  12. De Novo Structure-Based Design of Anion Receptors

    SciTech Connect

    Hay, Benjamin [ORNL

    2010-01-01

    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.

  13. Photoelectron spectroscopy of boron aluminum hydride cluster anions.

    PubMed

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

    2014-04-28

    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

  14. Photoelectron spectroscopy of boron aluminum hydride cluster anions

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  15. Selective anion exchange and tunable luminescent behaviors of metal-organic framework based supramolecular isomers.

    PubMed

    Manna, Biplab; Singh, Shweta; Karmakar, Avishek; Desai, Aamod V; Ghosh, Sujit K

    2015-01-01

    Owing to the conformational (cis or trans) flexibility of a N-donor ligand, the combinations of the same and Cd(ClO4)2 under variable solvent templates afforded two supramolecular isomers based on two-dimensional metal-organic frameworks. Both compounds contain weakly coordinating ClO4(-) anions attached to the metal centers. Both frameworks showed facile anion exchange behaviors with various kinds of foreign anions. Moreover, both frameworks showed anion-driven structural dynamism and exhibited the preferential uptake of strongly coordinating anions over others. Anion-regulated modulation in luminescent behaviors was also observed in both cases. PMID:25492519

  16. On the coexistence of localized and extended acceptor states in high gap semiconductors

    NASA Astrophysics Data System (ADS)

    Schirmer, O. F.

    2015-02-01

    Holes introduced into high gap materials by acceptor doping are often self-localized at anion sites as small polarons bound to the doping elements. The related lattice distortion lowers the hole energy; the hole levels thus tend to be deep. Electronic structure calculations of small polarons have identified, for some dopings, that such localized states can coexist with extended ones that result from the same doping. Using a scaling formalism, proposed by Emin and Holstein, it is shown that this appears to be a general phenomenon if the polaron-forming short-range hole–lattice coupling is taken into account.

  17. Gap Test Calibrations and Their Scaling

    NASA Astrophysics Data System (ADS)

    Sandusky, Harold

    2011-06-01

    Common tests for measuring the threshold for shock initiation are the NOL large scale gap test (LSGT) with a 50.8-mm diameter donor/gap and the expanded large scale gap test (ELSGT) with a 95.3-mm diameter donor/gap. Despite the same specifications for the explosive donor and polymethyl methacrylate (PMMA) gap in both tests, calibration of shock pressure in the gap versus distance from the donor scales by a factor of 1.75, not the 1.875 difference in their sizes. Recently reported model calculations suggest that the scaling discrepancy results from the viscoelastic properties of PMMA in combination with different methods for obtaining shock pressure. This is supported by the consistent scaling of these donors when calibrated in water-filled aquariums. Calibrations with water gaps will be provided and compared with PMMA gaps. Scaling for other donor systems will also be provided. Shock initiation data with water gaps will be reviewed.

  18. Is There a Gap in the Gap? Regional Differences in the Gender Pay Gap

    Microsoft Academic Search

    Boris Hirsch; Marion König; Joachim Möller

    2009-01-01

    In this paper, we investigate regional differences in the gender pay gap both theoretically and empirically. Within a spatial oligopsony model, we show that more densely populated labour markets are more competitive and constrain employers' ability to discriminate against women. Utilising a large administrative data set for western Germany and a flexible semi-parametric propensity score matching approach, we find that

  19. Communication: Stabilization of radical anions with weakly bound electron in condensed media: A case study of diacetonyl radical anion

    NASA Astrophysics Data System (ADS)

    Saenko, Elizaveta V.; Laikov, Dimitri N.; Baranova, Irina A.; Feldman, Vladimir I.

    2011-09-01

    The radical anion resulting from electron capture by diacetonyl molecule has been characterized by EPR and optical absorption spectroscopy in glassy ether matrices at 77 K. In non-polar alkane glasses this species was not observed under the same conditions, which confirms the crucial role of matrix interactions in stabilizing this species. Calculations at the MP2 level show the vertical detachment energy to increase gradually from roughly zero for a bare anion to ˜1 eV for the complex involving six ether molecules.

  20. Gaps"

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2013

    2013-01-01

    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…

  1. Emplacement Gantry Gap Analysis Study

    SciTech Connect

    R. Thornley

    2005-05-27

    To date, the project has established important to safety (ITS) performance requirements for structures, systems, and components (SSCs) based on the identification and categorization of event sequences that may result in a radiological release. These performance requirements are defined within the ''Nuclear Safety Design Bases for License Application'' (NSDB) (BSC 2005 [DIRS 171512], Table A-11). Further, SSCs credited with performing safety functions are classified as ITS. In turn, assurance that these SSCs will perform as required is sought through the use of consensus codes and standards. This gap analysis is based on the design completed for license application only. Accordingly, identification of ITS SSCs beyond those defined within the NSDB are based on designs that may be subject to further development during detail design. Furthermore, several design alternatives may still be under consideration to satisfy certain safety functions, and final selection will not be determined until further design development has occurred. Therefore, for completeness, alternative designs currently under consideration will be discussed throughout this study. This gap analysis will evaluate each code and standard identified within the ''Emplacement Gantry ITS Standards Identification Study'' (BSC 2005 [DIRS 173586]) to ensure each ITS performance requirement is fully satisfied. When a performance requirement is not fully satisfied, a gap is highlighted. This study will identify requirements to supplement or augment the code or standard to meet performance requirements. Further, this gap analysis will identify nonstandard areas of the design that will be subject to a design development plan. Nonstandard components and nonstandard design configurations are defined as areas of the design that do not follow standard industry practices or codes and standards. Whereby, assurance that an SSC will perform as required may not be readily sought though the use of consensus standards. This gap analysis is prepared by the Emplacement and Retrieval (E&R) project team and is intended for the sole use of the Engineering department in work regarding the emplacement gantry. Yucca Mountain Project personnel from the E&R project team should be consulted before use of this gap analysis for purposes other than those stated herein or by individuals other than authorized by the Engineering department.

  2. Transport and phase behavior in anion-conducting diblock copolymers

    NASA Astrophysics Data System (ADS)

    Sudre, Guillaume; Inceoglu, Sebnem; Balsara, Nitash

    2012-02-01

    Anion-exchange membranes can be used in various applications such as direct methanol fuel cells or devices for artificial photosynthesis. Consequently, these membranes have to conduct the anions efficiently, remain insoluble in water or methanol, and be impermeable to various gases. Block copolymers are good candidates to reach these aims. Their ability to self-assemble, particularly into bi-continuous phases, makes it possible to use one polycationic block that would conduct the anions, while a second neutral block can be designed as a structural block to insure the mechanical stability of the system. Our study focuses on the relationship between phase behavior and anion conductivity of diblock copolymers as a function of molecular weight, composition and cationic groups. We have chosen to use a model system made of styrene for the neutral block, and of chloromethylstyrene for the second block since it is easily cationizable with various functionalities, reacting easily with e.g. trimethylamine or n-butylimidazole. This model system is synthesized by nitroxide-mediated radical polymerization with molecular weights between 2 to 40 kg/mol and fractions of chloromethylstyrene in the range of 15-40 mol%. The results obtained from small-angle X-ray scattering showed lamellar morphologies for most systems. The temperature-dependence of the conductivity was assessed by performing measurements on membranes that were either immersed in water or in a controlled atmosphere at 98% of relative humidity.

  3. Anion photoelectron spectroscopy of solvated transition state precursors

    NASA Astrophysics Data System (ADS)

    Gómez, Harry; Meloni, Giovanni; Madrid, James; Neumark, Daniel M.

    2003-07-01

    Photoelectron (PE) spectra have been collected for the clustered bihalide anions XHX-•(M) (X=Br, I) and BrHI-•(M), where M=H2O, HBr, and HI, in order to probe the effects of strongly solvating species on the PE spectra of transition state precursor anions. The PE spectra of the XHX-•(H2O) ions show similar vibrational progressions as the spectra of the bare BrHBr- and IHI- anions, indicating that photodetachment of the bare and hydrated ions accesses similar XHX transition state geometries on the X+HX reaction potential energy surfaces. These results are consistent with electronic structure calculations that predict a double hydrogen-bonded XHX-•(H2O) structure in which the symmetry of the strong XHX- hydrogen bond is largely preserved. In contrast, PE spectra of BrHBr-(HBr)1,2 and IHI-(HI)1,2 indicate that the addition of a single HBr or HI disrupts the symmetric XHX- bond, resulting in structures of the form X-•(HX)n, and altering the geometry of the Franck-Condon region accessed on the neutral potential energy surfaces. Similarly, PE spectra of BrHI-•(HI) and BrHI-•(HBr) suggest anion structures of the form I-•(HBr)HI and I-•(HBr)2, respectively.

  4. Supporting Information for: Ammonium Bicarbonate Transport in Anion Exchange Membranes

    E-print Network

    S1 Supporting Information for: Ammonium Bicarbonate Transport in Anion Exchange Membranes was measured by first equilibrating the polymer film in the desired solution [e.g., DI water, 0.5 mol/L sodium chloride (NaCl), or 0.5 mol/L ammonium bicarbonate (AmB)]. Films were allowed to equilibrate

  5. Superoxide Anions and Endothelial Cell Proliferation in Normoglycemia and Hyperglycemia

    E-print Network

    Engelhardt, John F.

    Superoxide Anions and Endothelial Cell Proliferation in Normoglycemia and Hyperglycemia Michela and hyperglycemia. Human aortic endothelial cells (HAECs) and human umbilical vein endothelial cells (HUVECs proliferation, and the inhibitory effect of increased superoxide due to hyperglycemia can be reversed by Cu

  6. Synthesis, characterization, anion complexation and electrochemistry of cationic Lewis acids

    E-print Network

    Chiu, Ching-Wen

    2009-05-15

    .86 and -1.56 (vs. Fc/Fc+) corresponding to the formation of stable neutral and anionic derivatives. The one-electron reduction of [27]+ leads to the formation of a boron containing neutral radical featuring an unusual boron-carbon one-electron ? bond...

  7. Cationic Main Group Compounds as Water Compatible Small Anion Receptors

    E-print Network

    Leamer, Lauren Anne

    2013-05-06

    The fluoride anion plays an important role in dental health and as a result is added to drinking water at low concentrations. If the concentration of fluoride is too high however, skeletal fluorosis can occur. Because of this, there has been...

  8. Catalytic Asymmetric Fluorination Through an Anionic Phase Transfer Strategy

    E-print Network

    Toste, Dean

    Catalytic Asymmetric Fluorination Through an Anionic Phase Transfer Strategy Aaron D. Lackner, Dr in a growing and industrially-relevant field involving cationic reagents? Electrophilic fluorination commonly employs cationic fluorine sources like Selectfluor®. Hamilton, G. L.; Kanai,T.;Toste, F. D. J

  9. The electronic structure of TEMPO, its cation and anion

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  10. Removal of Pesticides from Water by Anionic Clays

    NASA Astrophysics Data System (ADS)

    Lakraimi, M.; Legrouri, A.; Barroug, A.; de Roy, A.; Besse, J.-P.

    1999-03-01

    The exchange of chloride ions by ions from the pesticide family 2.4-dichlorophe- noxyacetate (2.4D) in ?Zn-Al-Cl? anionic clay was investigated by X-ray diffraction and infrared spectroscopy. The effects of 2.4D concentration in solution and temperature on the ion exchange were studied. The best sample in terms of crystallinity, was obtained at 100°C with a 2.4D concentration corresponding to the solubility limit of the ion in water. This sample was further characterised by chemical analyses and scanning electron microscopy. The anion intercalation was effected without degradation of the pesticide anion. L'échange des ions chlorure par les ions d'une molécule appartenant à la famille des pesticides 2,4-dichlorophénoxyacétate (2,4D) dans l'argile anionique [Zn-Al-Cl] a été étudiée par diffraction des rayons X et spectroscopie infrarouge. Les influences de la concentration en 2,4D de la solution d'échange et de la température ont été étudiées afin d'optimiser les conditions de l'échange. La meilleure cristallinité a été obtenue à 100°C dans une solution 0.004 M en 2,4D. Une phase préparée dans ces conditions a été caractérisée par analyse chimique et microscopie électronique à balayage. L'échange a été réalisée sans dégradation de l'anion pesticide.

  11. 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...

  12. Anions of low Lewis basicity for ionic solid state electrolytes

    Microsoft Academic Search

    Wolfgang Linert; Aurore Camard; Michel Armand; Christophe Michot

    2002-01-01

    Methods for the estimation of Lewis basicity of anions, especially of those showing low and very low donor properties are reported. These properties are of importance for technical applications, for example, when applying them as conducting salts for batteries or in catalytic systems both of which are shortly reviewed.

  13. The Determination of Anionic Surfactants in Natural and Waste Waters.

    ERIC Educational Resources Information Center

    Crisp, P. T.; And Others

    1983-01-01

    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…

  14. The adsorption behavior of heavy metals on anionic surfactant micelles

    SciTech Connect

    Yuan, C.; Hung, C.H.

    1999-07-01

    The adsorption behaviors of monovalent metal ion (Na) and divalent metal ions (Cu, Cd and Pb,) on micelles composed of the anionic surfactant, dodecylsulfate (DS{sup {minus}}) were investigated in ultrafiltration experiments in this study. The anionic surfactant molecule consists of a polar moiety with negative charge and a nonpolar moiety with neutral charge. As the surfactant concentration is greater than the critical micelle concentration (cmc), a surfactant molecule will aggregate with other surfactant molecules to form micelles which surfaces are surrounded with negative charges. Due to columbic attraction, the heavy metals will be adsorbed on the micelle surface. The experimental results indicate that the anionic micelles have a higher affinity for divalent species than for the monovalent specie. However, a high concentration of Na{sup +} competes for surface area diminishing the ability of the DS{sup {minus}} to adsorb either divalent species. At experimental conditions from 0 to 100 mM NaCl addition, the percentage of Na, Cu, Cd and Pb, adsorbed on micelle surface are 17.4{approximately}3.7%, 77.8{approximately}31.1%, 85.7{approximately}10.0% and 83.4{approximately}19.4%, respectively. The results show that the removal of heavy metals by anionic surfactant micelles is practical as fewer monovalent metals are exists.

  15. Electron sharing and anion-? recognition in molecular triangular prisms.

    PubMed

    Schneebeli, Severin T; Frasconi, Marco; Liu, Zhichang; Wu, Yilei; Gardner, Daniel M; Strutt, Nathan L; Cheng, Chuyang; Carmieli, Raanan; Wasielewski, Michael R; Stoddart, J Fraser

    2013-12-01

    Stacking on a full belly: Triangular molecular prisms display electron sharing among their triangularly arranged naphthalenediimide (NDI) redox centers. Their electron-deficient cavities encapsulate linear triiodide anions, leading to the formation of supramolecular helices in the solid state. Chirality transfer is observed from the six chiral centers of the filled prisms to the single-handed helices. PMID:24227594

  16. Infrared Spectroscopy of Hydrated Bicarbonate Anion Clusters: HCO3

    E-print Network

    Neumark, Daniel M.

    is thus important in processes such as pH homeostasis in oceans,1 the formation of external skeletons and the regulation of blood pH. The nucleophilic attack of the hydroxide anion on CO2, is a benchmark for the study

  17. Ultraviolet photoelectron spectroscopy of molybdenum and molybdenum monoxide anions

    E-print Network

    Lineberger, W. Carl

    Ultraviolet photoelectron spectroscopy of molybdenum and molybdenum monoxide anions Robert F photoelectron spectra of Mo and MoO have been measured. The electron affinity of atomic molybdenum is 0.748 2 eV and that of molybdenum monoxide is 1.290 6 eV. The term energies of several MoO electronic states not previously observed

  18. Metabolism, Longevity and Epigenetics

    PubMed Central

    Cosentino, Claudia; Mostoslavsky, Raul

    2013-01-01

    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

  19. Metabolic Syndrome and Migraine

    PubMed Central

    Sachdev, Amit; Marmura, Michael J.

    2012-01-01

    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

  20. Hard-gapped Holographic Superconductors

    E-print Network

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

    2009-12-05

    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.

  1. Electronic gap sensor and method

    DOEpatents

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

    1991-08-06

    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.

  2. Electronic gap sensor and method

    DOEpatents

    Williams, Robert S. (Fairfield, OH); King, Edward L. (Trenton, OH); Campbell, Steven L. (Middletown, OH)

    1991-01-01

    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.

  3. Extend the omnidirectional electronic gap of Thue-Morse aperiodic gapped graphene superlattices

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengren; Li, Hongqiang; Gong, Zhijie; Fan, Yuancheng; Zhang, Tianqi; Chen, Hong

    2012-12-01

    An effective way used to extend omnidirectional electronic gap (OEG) by using Thue-Morse gapped graphene superlattice (GSL) heterostructure is proposed. The heterostructure consists of different Thue-Morse gapped graphene superlattices with different width ratios of potentials. The optimal potential width ratios of constituent Thue-Morse gapped graphene superlattices are easy to be established owing to the lower and upper energy edges of omnidirectional electronic gap depend on the width ratio of potentials. Furthermore, the omnidirectional electronic gap is independence of structure order, thus we can use different optimal Thue-Morse gapped graphene superlattices of any structure order to form a heterostructure to extend this gap as desired.

  4. Saturated anionic phospholipids enhance transdermal transport by electroporation.

    PubMed Central

    Sen, Arindam; Zhao, Ya-Li; Hui, Sek Wen

    2002-01-01

    Anionic phospholipids, but not cationic or neutral phospholipids, were found to enhance the transdermal transport of molecules by electroporation. When added as liposomes to the milieus of water-soluble molecules to be delivered through the epidermis of porcine skin by electroporation, these phospholipids enhance, by one to two orders of magnitude, the transdermal flux. Encapsulation of molecules in liposomes is not necessary. Dimyristoylphosphatidylserine (DMPS), phosphatidylserine from bovine brain (brain-PS), dioleoylphosphatidylserine (DOPS), and dioleoylphosphatidylglycerol (DOPG) were used to test factors affecting the potency of anionic lipid transport enhancers. DMPS with saturated acyl chains was found to be a much more potent transport enhancer than those with unsaturated acyl chains (DOPS and DOPG). There was no headgroup preference. Saturated DMPS was also more effective in delaying resistance recovery after pulsing, and with a greater affinity in the epidermis after pulsing. Using fluorescent carboxyl fluorescein and fluorescein isothiocyanate (FITC)-labeled Dextrans as test water-soluble molecules for transport, and rhodamine-labeled phospholipids to track anionic phospholipids, we found, by conventional and confocal fluorescence microscopy, that transport of water-soluble molecules was localized in local transport spots or regions (LTRs) created by the electroporation pulses. Anionic phospholipids, especially DMPS, were located at the center of the LTRs and spanned the entire thickness of the stratum corneum (SC). The degree of saturation of anionic phospholipids made no difference in the densities of LTRs created. We deduce that, after being driven into the epidermis by negative electric pulses, saturated anionic phospholipids mix and are retained better by the SC lipids. Anionic lipids prefer loose layers or vesicular rather than multilamellar forms, thereby prolonging the structural recovery of SC lipids to the native multilamellar form. In the presence of 1 mg/ml DMPS in the transport milieu, the flux of FITC-Dextran-4k was enhanced by 80-fold and reached 175 microg/cm(2)/min. Thus, the use of proper lipid enhancers greatly extends the upper size limit of transportable chemicals. Understanding the mechanism of lipid enhancers enables one to rationally design better enhancers for transdermal drug and vaccine delivery by electroporation. PMID:12324424

  5. Energy Gaps in Graphene Nanoribbons

    Microsoft Academic Search

    Young-Woo Son; Marvin L. Cohen; Steven G. Louie

    2006-01-01

    Based on a first-principles approach, we present scaling rules for the band\\u000agaps of graphene nanoribbons (GNRs) as a function of their widths. The GNRs\\u000aconsidered have either armchair or zigzag shaped edges on both sides with\\u000ahydrogen passivation. Both varieties of ribbons are shown to have band gaps.\\u000aThis differs from the results of simple tight-binding calculations or solutions

  6. Atmospheric Scales and Spectral Gaps

    Microsoft Academic Search

    Franz Fiedler; Hans A. Panofsky

    1970-01-01

    The kinetic energy of the atmosphere is not spread uniformly over all wavelengths but has certain preferred scales, with gaps in between.Typically atmospheric structures are either fully three dimensional with horizontal wavelengths of the order of 100 m to several kilometers, such as convection cells (including thunderstorms) and mechanically driven eddies; or they are quasi-two-dimensional with horizontal dimensions of order

  7. Gating of gap junction channels.

    PubMed Central

    Spray, D C; White, R L; de Carvalho, A C; Harris, A L; Bennett, M V

    1984-01-01

    Gap junctional conductance ( gj ) in various species is gated by voltage and intracellular pH (pHi). In amphibian embryos, gj is reduced to half by a 14 mV transjunctional voltage ( Vj ), a change that in fish embryo requires approximately 28 mV. Crayfish septate axon and pairs of dissociated rat myocytes show no voltage dependence of gj over a range of Vj greater than +/- 50 mV. In fish and amphibian blastomeres , gj is steeply decreased by decrease in pHi (n, Hill coefficient: 4.5) and the apparent pKH (7.3) is in the physiological range. In crayfish septate axon the pKH is lower (6.7) and the curve is less steep (n = 2.7). Rises in cytoplasmic Ca can also decrease gj but much higher concentrations are required (greater than 0.1 mM in fish blastomeres). Voltage and pH gates on gap junctions in amphibian embryos appear independent. In squid blastomeres pH gates exhibit some sensitivity to potential, both transjunctional and between inside and outside. A pharmacology of gap junctions is being developed: certain agents block gj directly (aldehydes, alcohols, NEM in crayfish); others block by decreasing pHi (esters that are hydrolyzed by intrinsic esterases, NEM in vertebrates, and, as in the experiments demonstrating the effect of pHi, weak acids). Certain agents block pH sensitivity without affecting voltage dependence (retinoic acid, glutaraldehyde, EEDQ), further indicating separateness of pH and voltage gates. These studies demonstrate a dynamics of gap junctional conductance and variability in gating in a series of possibly homologous membrane channels. Images FIGURE 6 PMID:6324905

  8. Hyper-active gap filling

    PubMed Central

    Omaki, Akira; Lau, Ellen F.; Davidson White, Imogen; Dakan, Myles L.; Apple, Aaron; Phillips, Colin

    2015-01-01

    Much work has demonstrated that speakers of verb-final languages are able to construct rich syntactic representations in advance of verb information. This may reflect general architectural properties of the language processor, or it may only reflect a language-specific adaptation to the demands of verb-finality. The present study addresses this issue by examining whether speakers of a verb-medial language (English) wait to consult verb transitivity information before constructing filler-gap dependencies, where internal arguments are fronted and hence precede the verb. This configuration makes it possible to investigate whether the parser actively makes representational commitments on the gap position before verb transitivity information becomes available. A key prediction of the view that rich pre-verbal structure building is a general architectural property is that speakers of verb-medial languages should predictively construct dependencies in advance of verb transitivity information, and therefore that disruption should be observed when the verb has intransitive subcategorization frames that are incompatible with the predicted structure. In three reading experiments (self-paced and eye-tracking) that manipulated verb transitivity, we found evidence for reading disruption when the verb was intransitive, although no such reading difficulty was observed when the critical verb was embedded inside a syntactic island structure, which blocks filler-gap dependency completion. These results are consistent with the hypothesis that in English, as in verb-final languages, information from preverbal noun phrases is sufficient to trigger active dependency completion without having access to verb transitivity information.

  9. Prometheus and the Keeler gap

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  10. Appearance size of poly-anionic aluminum clusters, Aln z-, z = 2-5*

    NASA Astrophysics Data System (ADS)

    Martinez, Franklin; Bandelow, Steffi; Breitenfeldt, Christian; Marx, Gerrit; Schweikhard, Lutz; Wienholtz, Frank; Ziegler, Falk

    2013-02-01

    The production of poly-anionic metal clusters by simultaneous storage of electrons and cluster anions in a Penning trap has been extended to the fifth charge state. The minimum cluster size, required to attach a fifth excess electron, has been experimentally determined for aluminum clusters. A refined data evaluation method is proposed, redefining the appearance size with respect to the delayed electron emission. It has been applied to the penta-anions as well as to previous data of poly-anionic aluminum clusters. In addition, new measurements of aluminum di-anions have revealed a lower minimum appearance size than reported earlier. Comparison of the experimental results with predictions by the conducting-sphere model for the di-, tri-, tetra- and penta-anions show deviations that are probably due to thermal excitation of the cluster anions. The cluster-size dependence of the poly-anion abundance spectra is qualitatively reproduced by thermionic emission.

  11. Lipid Segregation in Membranes of Anionic Liposomes Adsorbed onto Polycationic Brushes.

    PubMed

    Yaroslavov, Alexander A; Sybachin, Andrey V; Zaborova, Olga V; Orlov, Viktor N; Ballauff, Matthias; Talmon, Yeshayahu; Menger, Fredric M

    2013-10-01

    Two-phased: Complexation of liposomes to spherical polycationic brushes induces lipid segregation in the liposomal membrane. The greater the initial anionic lipid content in the membrane, the more the electroneutral lipid dilutes the induced anionic clusters. PMID:24092540

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

    E-print Network

    Collum, David B.

    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

  13. Localization of Anionic Phospholipids in Escherichia coli Cells

    PubMed Central

    Oliver, Piercen M.; Crooks, John A.; Leidl, Mathias; Yoon, Earl J.; Saghatelian, Alan

    2014-01-01

    Cardiolipin (CL) is an anionic phospholipid with a characteristically large curvature and is of growing interest for two primary reasons: (i) it binds to and regulates many peripheral membrane proteins in bacteria and mitochondria, and (ii) it is distributed asymmetrically in rod-shaped cells and is concentrated at the poles and division septum. Despite the growing number of studies of CL, its function in bacteria remains unknown. 10-N-Nonyl acridine orange (NAO) is widely used to image CL in bacteria and mitochondria, as its interaction with CL is reported to produce a characteristic red-shifted fluorescence emission. Using a suite of biophysical techniques, we quantitatively studied the interaction of NAO with anionic phospholipids under physiologically relevant conditions. We found that NAO is promiscuous in its binding and has photophysical properties that are largely insensitive to the structure of diverse anionic phospholipids to which it binds. Being unable to rely solely on NAO to characterize the localization of CL in Escherichia coli cells, we instead used quantitative fluorescence microscopy, mass spectrometry, and mutants deficient in specific classes of anionic phospholipids. We found CL and phosphatidylglycerol (PG) concentrated in the polar regions of E. coli cell membranes; depletion of CL by genetic approaches increased the concentration of PG at the poles. Previous studies suggested that some CL-binding proteins also have a high affinity for PG and display a pattern of cellular localization that is not influenced by depletion of CL. Framed within the context of these previous experiments, our results suggest that PG may play an essential role in bacterial physiology by maintaining the anionic character of polar membranes. PMID:25002539

  14. Evolution of Metabolism

    NASA Astrophysics Data System (ADS)

    Nealson, K. H.; Rye, R.

    2003-12-01

    This chapter is devoted to the discussion of the evolution of metabolism, with a particular focus towards redox metabolism and the utilization of redox energy by life. We will deal with various aspects of metabolism that involve direct interaction with, and the extraction of energy from, the environment (catabolic metabolism) and will talk briefly of the reactions that affect mineral formation and dissolution. However, we will de-emphasize the aspects related to the formation of complex molecules and organisms. To some, it will be refreshingly brief; to others, somewhat superficial. This is unavoidable, as our knowledge of the details of the evolution of metabolism is at best slim. However, by piecing together aspects of the properties and history of the Earth and coupling these with what we know of today's metabolism, it is possible to at least frame several different hypotheses that, with time, should be possible to test and modify so that the next writing of this chapter might contain some intellectual entrees and not just the appetizers. Any discussion of metabolic evolution must occur in concert with a consideration of the Earth - the understanding of the forces that drove the co-evolution of life and Earth can be achieved only by considering them together. This theme will pervade this chapter, and any real understanding of the evolution of metabolism must be inexorably coupled to, and consistent with, the geological record of the Earth.The first aspect of evolution concerns the metabolic participants as we know them now (i.e., a definition of metabolic diversity), and the second concerns the sequence of events that have led to this remarkable metabolic diversity. The first part is fairly straightforward: a discussion of the domains of life, and the metabolic achievements that are expressed in the various domains, and relating metabolism to biogeochemical processes whenever possible. The second part is much more problematic. While it is possible to make up nearly any story regarding the evolution of metabolism (and nearly all have been attempted!), the starting point of life is not known (great debates still rage as to the nature and origin of the first living systems), and it is not a trivial matter to specify the sequence and timing of metabolic innovations. As will be discussed below, genetic and genomic data have revealed that genetic exchange between organisms has been so pervasive that it has essentially uncoupled the evolution of taxonomic groups from the evolution of metabolic processes, thus, obscuring the evolutionary trail with blurred signals. Given these challenges, it may be prudent at this time to admit what we do not know, and lay out the challenges for the coming years.

  15. Eicosanoids in Metabolic Syndrome

    PubMed Central

    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

    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

  16. Mevalonate metabolism in cancer.

    PubMed

    Gruenbacher, Georg; Thurnher, Martin

    2015-01-28

    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

  17. 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...

  18. Peripartal calcium homoeostasis of multiparous dairy cows fed rumen-protected rice bran or a lowered dietary cation/anion balance diet before calving

    PubMed Central

    Martín-Tereso, J; ter Wijlen, H; van Laar, H; Verstegen, M W A

    2014-01-01

    Milk fever is one of the most important metabolic diseases in dairy cattle. Reducing the dietary cation/anion balance (DCAD) with anionic salts is a common prevention strategy. However, many small European farms cannot use total mixed rations (TMR) in the close-up period. Including anionic salts in compound feeds can result in feed refusals and moderate inclusions to preserve feed palatability results in insufficient DCAD reduction. Rumen-protected rice bran induces the adaptation of Ca metabolism in dairy cows by a reduction of Ca intake and by a reduction of the availability of dietary Ca. In the presence of a negative control, rumen-protected rice bran (2.8 kg/day) was compared with a lowered DCAD diet (from 269 to 4 meq/kg DM) in their effect to prevent milk fever. In a randomized block design, 45 multiparous Holstein cows joined the trial sequentially from 21 days before the expected calving date and were observed until the 8th week of lactation. Feed and nutrient intakes were recorded, and Ca, P, Mg in serum and urine, urine pH, serum NEFA and milk production in early lactation were compared. Feeding rumen-protected rice bran before calving improved the recovery of calcaemia after calving and had a positive effect on DMI after calving. The moderately low DCAD diet did not positively influence serum Ca at calving. Calcaemia recovered even later than in control, and cows showed reduced DMI post-calving and higher NEFA levels in the first 36 h after calving. This moderate reduction of DCAD did not provide an intermediate prevention level indicating that DCAD needs to be reduced to the recommended levels to prevent milk fever. Rumen-protected rice bran may be a suitable feed to reduce hypocalcaemia post-partum and can be included in pre-calving compound feeds representing a palatable alternative to anionic salts. PMID:24138155

  19. A Reluctance Actuator Gap Disturbance Testbed

    E-print Network

    Meléndez H., Roberto J

    2014-01-01

    We have designed and built a Reluctance Actuator Gap Disturbance Testbed. The testbed emulates the short stroke and long stroke interaction of modern lithography stages. The testbed can be used to impart gap disturbance ...

  20. Direct band gap wurtzite gallium phosphide nanowires.

    PubMed

    Assali, S; Zardo, I; Plissard, S; Kriegner, D; Verheijen, M A; Bauer, G; Meijerink, A; Belabbes, A; Bechstedt, F; Haverkort, J E M; Bakkers, E P A M

    2013-04-10

    The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555-690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

  1. Direct Band Gap Wurtzite Gallium Phosphide Nanowires

    PubMed Central

    2013-01-01

    The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555–690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality. PMID:23464761

  2. 30 CFR 57.6603 - Air gap.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...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...

  3. 30 CFR 56.6603 - Air gap.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Explosives Extraneous Electricity § 56.6603 Air gap. At least a 15-foot air gap shall be provided between the blasting circuit and the electric...

  4. 30 CFR 57.6603 - Air gap.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...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...

  5. 30 CFR 57.6603 - Air gap.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...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...

  6. 30 CFR 56.6603 - Air gap.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Explosives Extraneous Electricity § 56.6603 Air gap. At least a 15-foot air gap shall be provided between the blasting circuit and the electric...

  7. 30 CFR 57.6603 - Air gap.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...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...

  8. 30 CFR 56.6603 - Air gap.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Explosives Extraneous Electricity § 56.6603 Air gap. At least a 15-foot air gap shall be provided between the blasting circuit and the electric...

  9. Penetration of erythrocyte membrane by peroxynitrite: participation of the anion exchange protein.

    PubMed

    Soszy?ski, M; Bartosz, G

    1997-10-01

    Participation of the anion exchange protein (Band 3 protein) of the erythrocyte membrane in the transport of peroxynitrite into erythrocytes was shown by partial inhibition of hemoglobin oxidation by extracellular peroxynitrite in cells treated with Band 3 inhibitors. These results demonstrate that permeation in the anionic form may be a minor pathway in the membrane transport of the peroxynitrite anion/peroxynitrous acid couple, especially in membranes reach in anion exchangers or channels. PMID:9350339

  10. An investigation of the anion-exchange resin method for soil phosphate extraction

    Microsoft Academic Search

    Erik Sibbesen

    1978-01-01

    Summary  The anion-exchange resin method for soil-phosphate extraction was investigated on 4 different soils under varying experimental\\u000a conditions. The variables were: (a) the type of anion-exchange resin, (b) the anionic form of the resin, (c) the ratio between\\u000a the amounts of resin, soil, and water, and (d) the time of shaking.\\u000a \\u000a The amount of P extracted was dependent on the anionic

  11. Simultaneous separation and detection of anions and thiophilic cations using capillary-size anion exchange chromatography with suppressed conductivity detection.

    PubMed

    Sötz, Veronika Anna; Kochmann, Sven

    2015-05-01

    In this fundamental study, the simultaneous separation and detection of anions and thiophilic cations in anion exchange chromatography with suppressed conductivity detection is investigated. Mercury(II) and cadmium(II) served as model analytes. Separation and detection was performed by introducing 2-mercaptoethanesulfonate, which forms complexes with both mercury and cadmium with a strong metal-sulfur bond, into the KOH eluent. Additional to the separation on the column, these complexes were able to pass the suppressor. Subsequently, they could be detected as negative peaks. A simple model for the separation mechanism was developed based on these results. Furthermore, the effect of the eluent concentration on the retention factors of both cation complexes and standard anions was examined and quantified. It revealed that the concentration of 2-mercaptoethanesulfonate has more influence on the cations than the KOH concentration. Also, 2.0 mM of 2-mercaptoethanesulfonate had about the same effect on the anion separation as 60 mM KOH. Finally, selectivity and detection limits were investigated. The detection limits were 4.9 ?M for mercury and 2.2 ?M for cadmium. PMID:25676801

  12. Single-crystal ?-Fe2O3 hexagonal nanorings: stepwise influence of different anionic ligands (F- and SCN- anions).

    PubMed

    Lv, Baoliang; Xu, Yao; Wu, Dong; Sun, Yuhan

    2011-01-21

    Single-crystal ?-Fe(2)O(3) hexagonal nanorings with hexagonal inner hole were synthesized under the stepwise influence of different anionic ligands (F(-) and SCN(-)). This is a new method to design and modify crystal structures of transition metal oxide nanoparticles. PMID:21072432

  13. Anion- and Proton-Dependent Gating of ClC-4 Anion/Proton Transporter under Uncoupling Conditions

    PubMed Central

    Orhan, Gökce; Fahlke, Christoph; Alekov, Alexi K.

    2011-01-01

    ClC-4 is a secondary active transporter that exchanges Cl? ions and H+ with a 2:1 stoichiometry. In external SCN?, ClC-4 becomes uncoupled and transports anions with high unitary transport rate. Upon voltage steps, the number of active transporters varies in a time-dependent manner, resembling voltage-dependent gating of ion channels. We here investigated modification of the voltage dependence of uncoupled ClC-4 by protons and anions to quantify association of substrates with the transporter. External acidification shifts voltage dependence of ClC-4 transport to more positive potentials and leads to reduced transport currents. Internal pH changes had less pronounced effects. Uncoupled ClC-4 transport is facilitated by elevated external [SCN?] but impaired by internal Cl? and I?. Block by internal anions indicates the existence of an internal anion-binding site with high affinity that is not present in ClC channels. The voltage dependence of ClC-4 coupled transport is modulated by external protons and internal Cl? in a manner similar to what is observed under uncoupling conditions. Our data illustrate functional differences but also similarities between ClC channels and transporters. PMID:21354396

  14. Gap Year: Time off, with a Plan

    ERIC Educational Resources Information Center

    Torpey, Elka Maria

    2009-01-01

    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…

  15. The GAP Online LGBT Mental Health Curriculum

    Microsoft Academic Search

    Mary E. Barber; Jack Drescher; Vernon Rosario

    2012-01-01

    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

  16. Attractor Metabolic Networks

    PubMed Central

    De la Fuente, Ildefonso M.; Cortes, Jesus M.; Pelta, David A.; Veguillas, Juan

    2013-01-01

    Background The experimental observations and numerical studies with dissipative metabolic networks have shown that cellular enzymatic activity self-organizes spontaneously leading to the emergence of a Systemic Metabolic Structure in the cell, characterized by a set of different enzymatic reactions always locked into active states (metabolic core) while the rest of the catalytic processes are only intermittently active. This global metabolic structure was verified for Escherichia coli, Helicobacter pylori and Saccharomyces cerevisiae, and it seems to be a common key feature to all cellular organisms. In concordance with these observations, the cell can be considered a complex metabolic network which mainly integrates a large ensemble of self-organized multienzymatic complexes interconnected by substrate fluxes and regulatory signals, where multiple autonomous oscillatory and quasi-stationary catalytic patterns simultaneously emerge. The network adjusts the internal metabolic activities to the external change by means of flux plasticity and structural plasticity. Methodology/Principal Findings In order to research the systemic mechanisms involved in the regulation of the cellular enzymatic activity we have studied different catalytic activities of a dissipative metabolic network under different external stimuli. The emergent biochemical data have been analysed using statistical mechanic tools, studying some macroscopic properties such as the global information and the energy of the system. We have also obtained an equivalent Hopfield network using a Boltzmann machine. Our main result shows that the dissipative metabolic network can behave as an attractor metabolic network. Conclusions/Significance We have found that the systemic enzymatic activities are governed by attractors with capacity to store functional metabolic patterns which can be correctly recovered from specific input stimuli. The network attractors regulate the catalytic patterns, modify the efficiency in the connection between the multienzymatic complexes, and stably retain these modifications. Here for the first time, we have introduced the general concept of attractor metabolic network, in which this dynamic behavior is observed. PMID:23554883

  17. Multiple KCNQ Potassium Channel Subtypes Mediate Basal Anion Secretion from the Human Airway Epithelial Cell Line

    E-print Network

    Dellaire, Graham

    Multiple KCNQ Potassium Channel Subtypes Mediate Basal Anion Secretion from the Human Airway force for anion secretion from secretory epithelia. To investigate the role of KCNQ K+ channels in mediating rates of basal anion secretion across the human airway submucosal gland serous cell model

  18. Competition between three organic anions during regeneration process of calcined LDH

    Microsoft Academic Search

    Lucelena Patricio Cardoso; João Barros Valim

    2004-01-01

    The calcination of Layered Double Hydroxides (LDH) produces mixed oxides which can undergo rehydration when in contact with aqueous solution containing anions, regenerating the layered structure of LDH, with these anions in the interlayer space. This process is known as ‘memory effect’. In this work we studied the regeneration of LDH, by sorption of organic anions as terephthalate (TA), benzoate

  19. Neutral and Cationic Main Group Lewis Acids - Synthesis, Anion Complexation and Redox Properties

    E-print Network

    Dorsey, Christopher L.

    2010-07-14

    .................................................................................... 116 5.1.1 Diboranes as anion complexation agents .............................. 116 5.1.2 Diboranes for the selective binding of fluoride ..................... 118 5.1.3 Hybrid boron/mercury systems for selective fluoride binding.... Proposed reaction of A with anions. .............................................................. 5 Figure 8. Boron centered radical anions. ....................................................................... 7 Figure 9. One and two electron...

  20. Contribution of anion-? interactions to the stability of Sm/LSm proteins.

    PubMed

    Breberina, Luka M; Mil?i?, Miloš K; Nikoli?, Milan R; Stojanovi?, Sr?an ?

    2015-04-01

    We have analyzed the influence of anion-? interactions to the stability of Sm/LSm assemblies. The side chain of Glu is more likely to be in anion-? interactions than Asp. Phe has the highest occurrence in these interactions than the other two ? residues. Among the anion-? residue pairs, Glu-Phe residue pair showed the maximum number of anion-?. We have found hot-spot residues forming anion-? interactions, and Glu-Phe is the most common hot-spot interacting pair. The significant numbers of anion-? interacting residues identified in the dataset were involved in the formation of multiple anion-? interactions. More than half of the residues involved in these interactions are evolutionarily conserved. The anion-? interaction energies are distance and orientation dependent. It was found that anion-? interactions showed energy less than -15 kcal mol(-1), and most of them have energy in the range -2 to -9 kcal mol(-1). Solvent accessibility pattern of Sm/LSm proteins reveals that all of the interacting residues are preferred to be in buried regions. Most of the interacting residues preferred to be in strand. A significant percentage of anion-? interacting residues are located as stabilization centers and thus might provide additional stability to these proteins. The simultaneous interaction of anions and cations on different faces of the same ?-system has been observed. On the whole, the results presented in this work will be very useful for understanding the contribution of anion-? interaction to the stability of Sm/LSm proteins. PMID:25502146

  1. Calibration curves for some standard Gap Tests

    SciTech Connect

    Bowman, A.L.; Sommer, S.C.

    1989-01-01

    The relative shock sensitivities of explosive compositions are commonly assessed using a family of experiments that can be described by the generic term ''Gap Test.'' Gap tests include a donor charge, a test sample, and a spacer, or gap, between two explosives charges. The donor charge, gap material, and test dimensions are held constant within each different version of the gap test. The thickness of the gap is then varied to find the value at which 50% of the test samples will detonate. The gap tests measure the ease with a high-order detonation can be established in the test explosive, or the ''detonability,'' of the explosive. Test results are best reported in terms of the gap thickness at the 50% point. It is also useful to define the shock pressure transmitted into the test sample at the detonation threshold. This requires calibrating the gap test in terms of shock pressure in the gap as a function of the gap thickness. It also requires a knowledge of the shock Hugoniot of the sample explosive. We used the 2DE reactive hydrodynamic code with Forest Fire burn rates for the donor explosives to calculate calibration curves for several gap tests. The model calculations give pressure and particle velocity on the centerline of the experimental set-up and provide information about the curvature and pulse width of the shock wave. 10 refs., 1 fig.

  2. 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

  3. Subgroup Achievement and Gap Trends: Oklahoma, 2010

    ERIC Educational Resources Information Center

    Center on Education Policy, 2010

    2010-01-01

    This paper profiles the student subgroup achievement and gap trends in Oklahoma for 2010. Oklahoma made progress in narrowing achievement gaps for most major subgroups on the End-of-Instruction (EOI) test in Algebra I. Trends in achievement gaps could not be determined for other grades in math, or for any grades in reading, because the state…

  4. Gapping in Farsi: A Crosslinguistic Investigation

    ERIC Educational Resources Information Center

    Farudi, Annahita

    2013-01-01

    This dissertation explores a longstanding challenge in work on gapping through the empirical lens of gapping in Farsi (the Tehrani variant of Modern Persian). While gapping has much in common with more uncontroversial elliptical constructions such as VPE and sluicing, it also differs from ellipsis in ways that accounts combining TP or CP…

  5. Generation Gaps in Engineering? David J. Kim

    E-print Network

    Gabrieli, John

    Generation Gaps in Engineering? by David J. Kim B.S., Computer Science and Engineering;3 Generation Gaps in Engineering? by David J. Kim Submitted to the System Design and Management Program on May in Engineering and Management ABSTRACT There is much enthusiastic debate on the topic of generation gaps

  6. The evolution of the gender wage gap

    Microsoft Academic Search

    Astrid Kunze

    2005-01-01

    This article examines the evolution of the gender wage gap by the decomposition of the gap at various experience levels. For the analysis, we use rich administrative data on wage and work histories for West-German workers with apprenticeship training. We find a pronounced gap at entry into first employment, which stays virtually constant throughout the early career. Sex segregation in

  7. Gap sensing benefits in Conform™ extrusion machinery

    Microsoft Academic Search

    K. Khawaja; K. Althoefer; M. P. Clode; L. D. Seneviratne

    2004-01-01

    The work presents the results of production trials of a gap sensing system for continuous extrusion machinery. It is critical to maintain a precise pre-defined extrusion gap for the efficient running of the continuous extrusion process and to maintain product quality. A high temperature capacitive gap sensing system is designed and implemented on a copper extrusion machine in a production

  8. Supramolecular chemistry of selective anion recognition for anions of environmental relevance. Progress report, October 1996--July 1997

    SciTech Connect

    Bowman-James, K.; Wilson, G.S.; Kuczera, K. [Univ. of Kansas, Lawrence, KS (US); Moyer, B. [Oak Ridge National Lab., TN (US)

    1997-01-01

    'This project has as its focus the design and synthesis of polyammonium macrocyclic receptors for oxoanions of environmental importance. The basic research aspects of this project involve synthesis (and the search for improved synthetic methods), solid state structure determination and thermodynamics studies (to ascertain structural criteria for and strength of anion binding), and molecular dynamics simulations (to assess solution characteristics of the interactions between anions and their receptors). Applications-oriented goals include the fabrication of more efficient anion-selective electrodes and the use of these compounds in liquid- liquid separations. The latter goal is the subcontract with Bruce Moyer at Oak Ridge National Laboratory. This first year the authors have focused on nitrates and phosphates. Considerable progress has been made in the basic areas of synthesis, solid state Structure, and molecular dynamics. Anion selective electrodes have also be made which show promising selectivities for oxoanions of interest. Below are described the major findings and significance in the categories of synthesis, structure and molecular dynamics, and electrode studies. Synthesis. The synthesis of polyaza macrocycles which are the focus of these studies is often tedious and time-consuming. A major breakthrough which the authors have made this year is to identify other polyaza macrocycles, which also bind the desired anions, but which are simpler to synthesize via a two step Schiff base/reduction process with high yields. This is truly significant since now the authors can obtain large quantities of the macrocycles and do multiple studies at once (crystallizations, thermodynamics, electrode, and eventually separations). Most of their studies to date have focused on monocyclic systems, but they are now beginning to examine bicyclic macrocycles, which can be synthesized by the same method starting with the tetraamine known as tren.'

  9. 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...

  10. Epigenetics and metabolism.

    PubMed

    Keating, Samuel T; El-Osta, Assam

    2015-02-13

    The molecular signatures of epigenetic regulation and chromatin architectures are fundamental to genetically determined biological processes. Covalent and post-translational chemical modification of the chromatin template can sensitize the genome to changing environmental conditions to establish diverse functional states. Recent interest and research focus surrounds the direct connections between metabolism and chromatin dynamics, which now represents an important conceptual challenge to explain many aspects of metabolic dysfunction. Several components of the epigenetic machinery require intermediates of cellular metabolism for enzymatic function. Furthermore, changes to intracellular metabolism can alter the expression of specific histone methyltransferases and acetyltransferases conferring widespread variations in epigenetic modification patterns. Specific epigenetic influences of dietary glucose and lipid consumption, as well as undernutrition, are observed across numerous organs and pathways associated with metabolism. Studies have started to define the chromatin-dependent mechanisms underlying persistent and pathophysiological changes induced by altered metabolism. Importantly, numerous recent studies demonstrate that gene regulation underlying phenotypic determinants of adult metabolic health is influenced by maternal and early postnatal diet. These emerging concepts open new perspectives to combat the rising global epidemic of metabolic disorders. PMID:25677519

  11. The metabolic syndrome

    Microsoft Academic Search

    Robert H Eckel; Scott M Grundy; Paul Z Zimmet

    2005-01-01

    This constellation of metabolic disturbances, all risk factors for cardiovascular disease, was first described in the 1920s by Kylin, a Swedish physician, as the clustering of hypertension, hyperglycaemia, and gout. 2 Later, in 1947, Vague drew attention to upper body adiposity (android or male-type obesity) as the obesity phenotype that was commonly associated with metabolic abnormalities associated with type 2

  12. Oncogenic alterations of metabolism

    Microsoft Academic Search

    Chi V. Dang; Gregg L. Semenza

    1999-01-01

    Over seven decades ago, classical biochemical studies showed that tumors have altered metabolic profiles and display high rates of glucose uptake and glycolysis. Although these metabolic changes are not the fundamental defects that cause cancer, they might confer a common advantage on many different types of cancers, which allows the cells to survive and invade. Recent molecular studies have revealed

  13. 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

    Lu, Lixia; Yang, Fan; Yang, Xiurong

    2014-12-01

    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

  14. Focus on the Tax ‘Avoidance ’ Gap

    E-print Network

    Eric Toder

    President Obama’s tax reform task force has been asked to propose ways to close the $300 billion per-year tax gap by simplifying the tax code, reducing evasion, closing loopholes, and reducing corporate tax breaks. That $300 billion figure is an IRS estimate of the ‘‘net tax gap’ ’ for tax year 2001. The IRS defines the net tax gap as the difference between the amount taxpayers owe for a given tax year and the amount they pay on time, less what the IRS expects to recover in the future from voluntary late payments and enforcement activities. The apparent focus on the IRS-defined tax gap is the wrong agenda for a tax reform panel. The United States faces two tax gaps: the IRS measure of tax evasion and a second gap that may be called the legal avoidance gap. This second gap — the difference between taxes under an income tax without special preferences and taxes under current law — is much larger than the evasion gap, and there are ways to reduce it substantially, if the political will exists. Comparing the Two Tax Gaps Government agencies estimate both the ‘‘evasion’ ’ and ‘‘avoidance’’ gaps. There are major technical and conceptual problems in measuring both gaps, but the evasion gap is much harder to estimate. Reducing the evasion gap requires better monitoring of the behavior of individual and corporate taxpayers, but the perpetrators of the avoidance gap are legislators, not taxpayers. Both evasion and avoidance impose costs on the rest of us (higher tax rates to raise the same revenue, larger deficits, and less funding of public services). But measures to reduce them also have economic costs. Reducing evasion requires measures that increase the IRS budget and impose costs on audited

  15. Metabolic Engineering VII Conference

    SciTech Connect

    Kevin Korpics

    2012-12-04

    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.

  16. Metabolism of halophilic archaea

    PubMed Central

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

    2008-01-01

    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

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

    Microsoft Academic Search

    Dick M. Carpenter; Al Ramirez

    2007-01-01

    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

  18. DIABETES, OBESITY AND METABOLISM INSTITUTE

    E-print Network

    Engman, David M.

    DIABETES, OBESITY AND METABOLISM INSTITUTE AT NORTHWESTERN MEDICINE THE INSTITUTES AT NORTHWESTERN MEDICINE #12;THE INSTITUTES AT NORTHWESTERN MEDICINE DIABETES, OBESITY AND METABOLISM INSTITUTE AT NORTHWESTERN MEDICINE "As we launch the Diabetes, Obesity and Metabolism Institute at Northwestern Medicine, I

  19. Multiplicity Distributions and Rapidity Gaps

    E-print Network

    Jon Pumplin

    1994-07-19

    I examine the phenomenology of particle multiplicity distributions, with special emphasis on the low multiplicities that are a background in the study of rapidity gaps. In particular, I analyze the multiplicity distribution in a rapidity interval between two jets, using the HERWIG QCD simulation with some necessary modifications. The distribution is not of the negative binomial form, and displays an anomalous enhancement at zero multiplicity. Some useful mathematical tools for working with multiplicity distributions are presented. It is demonstrated that ignoring particles with pt<0.2 has theoretical advantages, in addition to being convenient experimentally.

  20. Translational gap in glioma research.

    PubMed

    Ma, Chi; Zhao, Gang; Cruz, Mabel Hilda; Siden, Ake; Yakisich, Juan Sebastian

    2014-01-01

    During the last five decades, enormous advances in treatment modalities for cancer and a better understanding of cancer cell biology have been accomplished but the prognosis of patients carrying malignant gliomas still remains poor despite hundreds of clinical trials have been carried out. In this article we review phase II clinical trials that have been completed and published in PubMed during 2011 in order to investigate potential reasons of clinical failure. We suggest that a translational gap, defined as a failure to translate basic research into clinical trials design may explain the poor outcome of phase II clinical trials. PMID:25175687

  1. Emission channeling studies on transition-metal doped GaN and ZnO: Cation versus anion substitution

    NASA Astrophysics Data System (ADS)

    Pereira, L. M. C.; Wahl, U.; Correia, J. G.; Amorim, L. M.; Silva, D. J.; Decoster, S.; da Silva, M. R.; Temst, K.; Vantomme, A.

    2014-08-01

    The magnetic and electric properties of impurities in semiconductors are strongly dependent on the lattice sites which they occupy. While the majority site can often be predicted based on chemical similarities with the host elements and is usually simple to confirm experimentally, minority sites are far more complicated to predict, detect and identify. We have carried out extensive ?- emission channeling studies on the lattice location of transition metal impurities in wide-gap dilute magnetic semiconductors, namely Co and Mn in GaN and ZnO, making use of radioactive 61Co and 56Mn implanted at the ISOLDE facility at CERN. In addition to the majority occupation of cation (Ga, Zn) sites, we located significant fractions (of the order of 20%) of the Co and Mn impurities in anion (N, O) sites, which are virtually unaffected by thermal annealing up to 900 °C. Here, we present the ?- emission channeling experiments on 61Co-implanted GaN. We discuss these results in the context of our recent reports of minority anion substitution in Mn-implanted GaN Pereira et al. (2012) [19] and Mn/Co-implanted ZnO Pereira et al. (2011) [20], particularly in terms of the advantages of the emission channeling technique in such cases of multi-site occupancy.

  2. Mutual influence between anion-? and pnicogen bond interactions: The enhancement of P?N and P?O interactions by an anion-? bond.

    PubMed

    Esrafili, Mehdi D; Mohammadian-Sabet, Fariba; Solimannejad, Mohammad

    2015-04-01

    In this work, the interplay between anion-? and pnicogen bond interactions is investigated by ab initio calculations. Cooperative effects are observed in the studied complexes in which anion-? and pnicogen bond interactions coexist. These effects are analyzed in detail in terms of the energetic, geometric, charge-transfer and electron density properties of the complexes. The cooperative energy ranges from -1.8 to -4.1kcalmol(-1). The effect of an anion-? bond on a pnicogen bond is more pronounced than that of a pnicogen bond on an anion-? bond. The enhancing mechanism is analyzed in views with the charge-transfer, electrostatic potential and electron density analysis. PMID:25698102

  3. Gap Test Calibrations And Their Scalin

    NASA Astrophysics Data System (ADS)

    Sandusky, Harold

    2012-03-01

    Common tests for measuring the threshold for shock initiation are the NOL large scale gap test (LSGT) with a 50.8-mm diameter donor/gap and the expanded large scale gap test (ELSGT) with a 95.3-mm diameter donor/gap. Despite the same specifications for the explosive donor and polymethyl methacrylate (PMMA) gap in both tests, calibration of shock pressure in the gap versus distance from the donor scales by a factor of 1.75, not the 1.875 difference in their sizes. Recently reported model calculations suggest that the scaling discrepancy results from the viscoelastic properties of PMMA in combination with different methods for obtaining shock pressure. This is supported by the consistent scaling of these donors when calibrated in water-filled aquariums. Calibrations and their scaling are compared for other donors with PMMA gaps and for various donors in water.

  4. Local impermeant anions establish the neuronal chloride concentration.

    PubMed

    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

    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

  5. Macrocyclic bis(ureas) as ligands for anion complexation.

    PubMed

    Kretschmer, Claudia; Dittmann, Gertrud; Beck, Johannes

    2014-01-01

    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 (1)H 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

  6. Macrocyclic bis(ureas) as ligands for anion complexation

    PubMed Central

    Kretschmer, Claudia; Dittmann, Gertrud

    2014-01-01

    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

  7. Gas-phase Reactions of Hydride Anion, H-

    NASA Astrophysics Data System (ADS)

    Martinez, Oscar, Jr.; Yang, Zhibo; Demarais, Nicholas J.; Snow, Theodore P.; Bierbaum, Veronica M.

    2010-09-01

    Rate constants were measured at 300 K for the reactions of the hydride anion, H-, with neutral molecules C2H2, H2O, CH3CN, CH3OH, (CH3)2CO, CH3CHO, N2O, CO2, O2, CO, CH3Cl, (CH3)3CCl, (CH3CH2)2O, C6H6, and D2 using a flowing-afterglow instrument. Experimental work was supplemented by ab initio calculations to provide insight into the viability of reaction pathways. Our reported rate constants should prove useful to models of astrophysical environments where conditions prevail for the existence of both H- and neutral species. The variety of neutral reactants studied includes representative species from prototypical chemical groups, effectively mapping reactivity trends for the hydride anion.

  8. Anion Conduction in PEO-Functionalized Polyphosphazene Ionomers

    NASA Astrophysics Data System (ADS)

    Bartels, Joshua; Hess, Andrew; Allcock, Harry; Colby, Ralph; Runt, James

    2013-03-01

    A series of novel polyphosphazene ionomers with short chain poly(ethylene oxide) (PEO) moieties, bound ammonium cations, and free iodide anions were previously synthesized. Ion dynamics during anion conduction of the ionomers were studied by dielectric relaxation spectroscopy (DRS). These polyphosphazenes provide interesting conductive materials to study because of their low glass transition temperature, high segmental mobility, and high ion content. Analysis of DRS results provides static dielectric constant, conducting ion mobility, and conducting ion content for the materials. An increase in the length of the alkyl group extending from the polymer-bound ammonium cation increases conductivity and conducting ion concentration due to new steric interactions weakening ion-ion associations that restrict segmental mobility. By placing ether oxygens in the short alkyl group a large increase in conductivity and a decrease in the glass transition temperature is observed due to strong associations between the cation and ether oxygen lone pairs.

  9. Cationic inorganic materials for anionic pollutant trapping and catalysis.

    PubMed

    Oliver, Scott R J

    2009-07-01

    Despite their vast industrial importance, almost all extended inorganic synthetic structures and naturally occurring minerals adopt a neutral or anionic charge. This tutorial review describes the current knowledge of inorganic materials that bear a positive charge on the host. The best-known example is the family of clays known as layered double hydroxides, and other limited examples also exist. Our research efforts have given rise to a series of new cationic inorganic materials, oxides and fluorides of heavy p-block metals. Organic-based cationic materials will also be briefly discussed. Interest in these materials is widespread, with potential applications in many areas including anionic pollutant trapping, exchange, selective catalysis, polymer hybrids and nanocomposites, and biomaterials for drug or DNA delivery. PMID:19551168

  10. Local Impermeant Anions Establish the Neuronal Chloride Concentration

    PubMed Central

    Glykys, J; Dzhala, V; Egawa, K; Balena, T; Saponjian, Y; Kuchibhotla, KV; Bacskai, BJ; Kahle, KT; Zeuthen, T; Staley, KJ

    2014-01-01

    Neuronal chloride concentration [Cl?]i is an important determinant of GABAA receptor (GABAAR)-mediated inhibition and cytoplasmic volume regulation. Equilibrative cation-chloride cotransporters (CCC) 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, CCC 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 GABAAR signaling. PMID:24503855

  11. Anion-switchable supramolecular gels for controlling pharmaceutical crystal growth

    NASA Astrophysics Data System (ADS)

    Foster, Jonathan A.; Piepenbrock, Marc-Oliver M.; Lloyd, Gareth O.; Clarke, Nigel; Howard, Judith A. K.; Steed, Jonathan W.

    2010-12-01

    We describe the use of low-molecular-weight supramolecular gels as media for the growth of molecular crystals. Growth of a range of crystals of organic compounds, including pharmaceuticals, was achieved in bis(urea) gels. Low-molecular-weight supramolecular gelators allow access to an unlimited range of solvent systems, in contrast to conventional aqueous gels such as gelatin and agarose. A detailed study of carbamazepine crystal growth in four different bis(urea) gelators, including a metallogelator, is reported. The crystallization of a range of other drug substances, namely sparfloxacin, piroxicam, theophylline, caffeine, ibuprofen, acetaminophen (paracetamol), sulindac and indomethacin, was also achieved in supramolecular gel media without co-crystal formation. In many cases, crystals can be conveniently recovered from the gels by using supramolecular anion-triggered gel dissolution; however, crystals of substances that themselves bind to anions are dissolved by them. Overall, supramolecular gel-phase crystallization offers an extremely versatile new tool in pharmaceutical polymorph screening.

  12. Properties of anionic surfactants affecting biodegradation of hydrocarbons

    SciTech Connect

    Rouse, J.D.; Sabatini, D.A.; Harwell, J.H. [Univ. of Oklahoma, Norman, OK (United States)

    1995-12-01

    Manometric respirometers were used to evaluate the influences of a wide range of anionic surfactants on microbial activity in systems containing a hydrocarbon substrate (naphthalene) and an activated sludge seed. Results showed that sulfated surfactants served as preferred substrates in the presence of naphthalene. Sulfonated surfactants, however, did not readily serve as substrates. Testing with a series of twin-head group anionic surfactants (diphenyl oxide disulfonates) indicated that microbial oxidation rates of naphthalene are generally enhanced at surfactant levels above the critical micelle concentration (CMC) in systems containing surfactants that have mid-range tail lengths (C10 to C16). With sodium dodecylbenzene sulfonate, however, oxidation of naphthalene was largely suppressed at supra-CMC levels. Results of sorption experiments of surfactants onto biomass demonstrated that direct interactions of surfactants with microorganisms are occurring.

  13. Dissolution of cellulose in room temperature ionic liquids: anion dependence.

    PubMed

    Payal, Rajdeep Singh; Bejagam, Karteek K; Mondal, Anirban; Balasubramanian, Sundaram

    2015-01-29

    The dissolution of cellulosic biomass in room temperature ionic liquids (RTILs) is studied through free energy calculations of its monomer, viz., cellobiose, within a molecular dynamics simulation approach. The solvation free energy (SFE) of cellobiose in ionic liquids containing any of seven different anions has been calculated. The ranking of these liquids based on SFE compares well with experimental data on the solubility of cellulose. The dissolution is shown to be enthalpically dominated, which is correlated with the strength of intermolecular hydrogen bonding between cellobiose and the anions of the IL. Large entropic changes upon solvation in [CF3SO3](-) and [OAc](-) based ionic liquids have been explained in terms of the solvent-aided conformational flexibility of cellobiose. PMID:25535797

  14. Alanate anion, AlH4(-): photoelectron spectrum and computations.

    PubMed

    Graham, J D; Buytendyk, A M; Zhang, X; Collins, E L; Kiran, B; Gantefoer, G; Eichhorn, B W; Gutsev, G L; Behera, S; Jena, P; Bowen, K H

    2014-09-18

    The alanate anion, AlH4(-), was generated in the gas phase using a pulsed arc cluster ionization source. Its photoelectron spectrum was then measured with 193 nm photons. The spectrum consists of a broad feature, spanning electron binding energies from 3.8 eV to over 5.3 eV. This band reflects the photodetachment transitions between the ground state of the AlH4(-) anion and the ground state of its thermodynamically unstable neutral counterpart, AlH4. The vertical detachment energy (VDE) of AlH4(-) was measured to be 4.4 eV. Additionally, VDE values were also computed in a comprehensive theoretical study and compared both with the previously computed value and with our experimentally determined value. PMID:24512169

  15. Bifunctional Crosslinking Agents Enhance Anion Exchange Membrane Efficacy for Vanadium Redox Flow Batteries.

    PubMed

    Wang, Wenpin; Xu, Min; Wang, Shubo; Xie, Xiaofeng; Lv, Yafei; Ramani, Vijay K

    2014-06-01

    A series of cross-linked fluorinated poly (aryl ether oxadiazole) membranes (FPAEOM) derivatized with imidazolium groups were prepared. Poly (N-vinylimidazole) (PVI) was used as the bifunctional cross-linking agent to: a) lower vanadium permeability, b) enhance dimensional stability, and c) concomitantly provide added ion exchange capacity in the resultant anion exchange membranes. At a molar ratio of PVI to FPAEOM of 1.5, the resultant membrane (FPAEOM-1.5 PVI) had an ion exchange capacity of 2.2 meq g-1, a vanadium permeability of 6.8×10-7 cm2 min-1, a water uptake of 68 wt.%, and an ionic conductivity of 22.0 mS cm-1, all at 25°C. Single cells prepared with the FPAEOM-1.5 PVI membrane exhibited a higher coulombic efficiency (> 92%) and energy efficiency (> 86%) after 40 test cycles in vanadium redox flow battery. The imidazolium cation showed high chemical stability in highly acidic and oxidizing vanadium solution as opposed to poor stability in alkaline solutions. Based on our DFT studies, this was attributed to the lower HOMO energy (-7.265 eV) of the HSO4- ion (compared to the OH- ion; -5.496 eV) and the larger HOMO-LUMO energy gap (6.394 eV) of dimethylimidazolium bisulfate ([DMIM] [HSO4]) as compared to [DMIM] [OH] (5.387 eV). PMID:24884171

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

    PubMed

    Orona, N S; Tasat, D R

    2012-06-15

    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? 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?. 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??). 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?? may act as the principal mediator of DNA damage while at higher doses the signaling pathway mediated by O?? 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. PMID:22561334

  17. The synthesis of new weakly coordinating diborate anions: anion stability as a function of linker structure and steric bulk.

    PubMed

    Hannant, Mark H; Wright, Joseph A; Lancaster, Simon J; Hughes, David L; Horton, Peter N; Bochmann, Manfred

    2006-05-28

    The successive addition of KCN and Ph3CCl to B(C6F4-C6F5-2)3 (PBB) affords triphenylmethyl salts of the [NC-PBB]- anion. By contrast, the analogous reaction with sodium dicyanamide followed by treatment with Ph(3)CCl leads to the zwitterionic aminoborane H2NB(C12F9)2C12F8, via nucleophilic attack on an o-F atom, together with CPh3[F-PBB]. Whereas treatment of [NC-PBB]- with either PBB or B(C6F5)3 fails to give isolable cyano-bridged diborates, the reaction of Me3SiNC-B(C6F5)3 with PBB in the presence of Ph3CCl affords [Ph3C][PBB-NC-B(C6F5)3]. Due to steric hindrance this anion is prone to borane dissociation. The longer linking group N(CN)2- gives the very voluminous anions [N[CNB(C6F5)3]2]- and [N(CN-PBB)2]-. A comparison of propylene polymerisations with rac-Me2Si(Ind)2ZrMe2 activated with the various boranes or trityl borates gives an anion-dependent activity sequence, in the order [NC-PBB]- < [MeB(C6F5)3]- < [MePBB]- approximately [PBB-NCB(C6F5)3]- approximately [N[CNB(C6F5)3]2]- < [F-PBB]-< [B(C6F5)4]- < [N(CN-PBB)2]-. The anion [N(CN-PBB)2]- gives a catalyst productivity about 2500 times higher than that of [NC-PBB]- and exceeds that of [B(C6F5)4]- based catalysts. The van der Waals volumes and surface areas of the anions have been calculated and provide a rationale for the observed reactivity trends in polymerisation reactions. PMID:16705340

  18. Discrete and infinite 1D, 2D/3D cage frameworks with inclusion of anionic species and anion-exchange reactions of Ag3L2 type receptor with tetrahedral and octahedral anions.

    PubMed

    Liu, Hong-Ke; Huang, Xiaohua; Lu, Tianhong; Wang, Xiujian; Sun, Wei-Yin; Kang, Bei-Sheng

    2008-06-28

    Complexes [PF6 subset(Ag3(titmb)2](PF6)2 (8) and {SbF6 subset[Ag3(titmb)2](SbF6)2}.H2O.1.5 CH3OH (9) are obtained by reaction of titmb and Ag+ salts with different anions (PF6(-) and SbF6(-)), and crystal structures reveal that they are both M3L2 cage complexes with short Ag...F interactions between the silver atoms and the fluorine atoms of the anions. In complex 8, a novel cage dimer is formed by weak Ag...F contacts; an unique cage tetramer formed via Ag...pi interactions (Ag...eta5-imidazole) between dimers and an infinite 1D cage chain is presented. However, each of the external non-disordered SbF6(-) anions connect with six cage 9s via Ag...F contacts, and each cage 9 in turn connects with three SbF6(-) anions to form a 2D network cage layer; and the layers are connected by pi-pi interactions to form a 3D network. The anion-exchange reactions of four Ag3L2 type complexes ([BF4 subset(Ag3(titmb)2](BF4)2 (6), [ClO4 subset(Ag3(titmb)2](ClO4)2 (7b), [PF6 subset(Ag3(titmb)2](PF6)2 (8) and [SbF6 subset(Ag3(titmb)2](SbF6)2.1.5CH3OH (9)) with tetrahedral and octahedral anions (ClO4(-), BF4(-), PF6(-) and SbF6(-)) are also reported. The anion-exchange experiments demonstrate that the anion selective order is SbF6(-) > PF6(-) > BF4(-), ClO4(-), and this anion receptor is preferred to trap octahedral and tetrahedral anions rather than linear or triangle anions; SbF6(-) is the biggest and most preferable one, so far. The dimensions of cage complexes with or without internal anions, anion-exchange reactions, cage assembly and anion inclusions, silver(I) coordination environments, Ag-F and Ag-pi interactions of Ag3L2 complexes 1-9 are discussed. PMID:18688416

  19. Gap Junctional Communication in Morphogenesis

    PubMed Central

    Levin, Michael

    2007-01-01

    Gap junctions permit the direct passage of small molecules from the cytosol of one cell to that of its neighbor, and thus form a system of cell-cell communication that exists alongside familiar secretion/receptor signaling. Because of the rich potential for regulation of junctional conductance, and directional and molecular gating (specificity), gap junctional communication (GJC) plays a crucial role in many aspects of normal tissue physiology. However, the most exciting role for GJC is in the regulation of information flow that takes place during embryonic development, regeneration, and tumor progression. The molecular mechanisms by which GJC establishes local and long-range instructive morphogenetic cues are just beginning to be understood. This review summarizes the current knowledge of the involvement of GJC in the patterning of both vertebrate and invertebrate systems and discusses in detail several morphogenetic systems in which the properties of this signaling have been molecularly characterized. One model consistent with existing data in the fields of vertebrate left-right patterning and anterior-posterior polarity in flatworm regeneration postulates electrophoretically-guided movement of small molecule morphogens through long-range GJC paths. The discovery of mechanisms controlling embryonic and regenerative GJC-mediated signaling, and identification of the downstream targets of GJC-permeable molecules, represent exciting next areas of research in this fascinating field. PMID:17481700

  20. Comment on "Local impermeant anions establish the neuronal chloride concentration".

    PubMed

    Luhmann, Heiko J; Kirischuk, Sergei; Kilb, Werner

    2014-09-01

    Glykys et al. (Reports, 7 February 2014, p. 670) proposed that cytoplasmic impermeant anions and polyanionic extracellular matrix glycoproteins establish the local neuronal intracellular chloride concentration, [Cl(-)]i, and thereby the polarity of ?-aminobutyric acid type A (GABAA) receptor signaling. The experimental procedures and results in this study are insufficient to support these conclusions. Contradictory results previously published by these authors and other laboratories are not referred to. PMID:25190788

  1. Gas-phase reactivity of ruthenium carbonyl cluster anions

    Microsoft Academic Search

    Matthew A. Henderson; Samantha Kwok; J. Scott McIndoe

    2009-01-01

    Partially-ligated anionic ruthenium carbonyl clusters react with alkenes, arenes, and alkanes in the gas phase; the products\\u000a undergo extensive C-H activation and lose dihydrogen and carbon monoxide under collision-induced dissociation conditions.\\u000a Triethylsilane and phenylsilane are also reactive towards the unsaturated clusters, and oxygen was shown to rapidly break\\u000a down the cluster core by oxidative cleavage of the metal-metal bonds. These

  2. Effect of Anions on Model Aluminum-Adjuvant-Containing Vaccines

    Microsoft Academic Search

    Joseph V. Rinella; Joe L. White; Stanley L. Hem

    1995-01-01

    The effect of adding phosphate, sulfate, or nitrate anions to model aluminum-adjuvant-containing vaccines at pH 7.4 was studied. Three different aluminum phosphate adjuvants were used that had phosphate to aluminum molar ratios of 1.31, 1.18, and 0.58. One aluminum hydroxide adjuvant was used. The isoelectric points of the adjuvants were inversely related to the degree of phosphate substitution for hydroxyl.

  3. Influence of anions on metal adsorption by Rhizopus arrhizus biomass

    Microsoft Academic Search

    J. M. Tobin; D. G. Cooper; R. J. Neufeld

    1987-01-01

    The presence of anions in solution was found to inhibit the uptake of La\\/sup 3 +\\/, Cd\\/sup 2 +\\/, Pb\\/sup 2 +\\/, UOâ\\/sup 2 +\\/, and Ag\\/sup +\\/ by Rhizopus arrhizus biomass. The effects ranged from total inhibition of Cd\\/sup 2 +\\/ and Pb\\/sup 2 +\\/ uptake at equimolar concentrations of EDTA to no change in uptake of La\\/sup 3

  4. Interactions between anionic and neutral bromine and rare gas atoms

    SciTech Connect

    Buchachenko, Alexei A.; Grinev, Timur A.; Wright, Timothy G.; Viehland, Larry A. [Department of Chemistry, Moscow State University, Moscow 119991 (Russian Federation); School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Division of Science, Chatham University, Pittsburgh, Pennsylvania 15232 (United States)

    2008-02-14

    High-quality, ab initio potential energy functions are obtained for the interaction of bromine atoms and anions with atoms of the six rare gases (Rg) from He to Rn. The potentials of the nonrelativistic {sup 2}{sigma}{sup +} and {sup 2}{pi} electronic states arising from the ground-state Br({sup 2}P)-Rg interactions are computed over a wide range of internuclear separations using a spin-restricted version of the coupled cluster method with single and double excitations and noniterative correction to triple excitations [RCCSD(T)] with an extrapolation to the complete basis set limit, from basis sets of d-aug-cc-pVQZ and d-aug-cc-pV5Z quality. These are compared with potentials derived previously from experimental measurements and ab initio calculations. The same approach is used also to refine the potentials of the Br{sup -}-Rg anions obtained previously [Buchachenko et al., J. Chem. Phys. 125, 064305 (2006)]. Spin-orbit coupling in the neutral species is included both ab initio and via an atomic approximation; deviations between two approaches that are large enough to affect the results significantly are observed only in the Br-Xe and Br-Rn systems. The resulting relativistic potentials are used to compute anion zero electron kinetic energy photoelectron spectra, differential scattering cross sections, and the transport coefficients of trace amounts of both anionic and neutral bromine in the rare gases. Comparison with available experimental data for all systems considered proves a very high precision of the present potentials.

  5. Salt splitting with radiation grafted PVDF anion-exchange membrane

    Microsoft Academic Search

    N. Tzanetakis; J. Varcoe; R. S. Slade; K. Scott

    2003-01-01

    A radiation grafted poly(vinylidene fluoride) anion-exchange membrane has been formulated and its behaviour is analysed through the splitting of sodium sulphate by electrohydrolysis. Experiments carried out in a two-compartment membrane electrolysis cell, investigated the influence of flow rate, current density and salt concentration on the performance of the membrane. The different flow conditions had a small influence on current efficiencies,

  6. Interaction of sulfophthaleine anions with cationic dyes in aqueous solution

    Microsoft Academic Search

    S. A. Shapovalov

    2010-01-01

    An interaction between the singly and doubly charged anions (HAn? and An2?) of sulfophthaleines (phenol red and its derivatives: bromophenol blue, bromocresol green, bromocresol purple, and bromothymol\\u000a blue), and singly charged cations (Ct+) of a polymethine (pinacyanol, quinaldine red), results in formation in an aqueous solution of heteroassociate with stoichiometric\\u000a composition (Ct+)·HAn? and (Ct+)2·An2?. On the basis of spectrophotometric data

  7. Homogeneous catalysis by transition metal oxygen anion clusters

    Microsoft Academic Search

    Craig L. Hill; Christina M. Prosser-McCartha

    1995-01-01

    This review provides a thorough discussion of homogeneous catalysis by transition metal oxygen anion clusters (polyoxometalates), with a focus on mechanism. The primary catalysts examined are mixed addenda and d-electron-transition-metal-substituted polyoxometalate (TMSP) complexes. The unusual versatility and tunability of these catalysts and their compatibility with environmentally and economically attractive conditions (solvents, oxidants, etc.) are outlined. A general compilation of the

  8. Anion receptor compounds for non-aqueous electrolytes

    SciTech Connect

    Lee, Hung Sui (East Setauket, NY); Yang, Xiao-Oing (Port Jefferson Station, NY); McBreen, James (Bellport, NY)

    2000-09-19

    A new family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the new family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of LI.sup.+ ion in alkali metal batteries.

  9. Development of anion-selective membranes. [for energy storage

    NASA Technical Reports Server (NTRS)

    Lacey, R. E.; Cowsar, D. R.

    1975-01-01

    Methods were studied of preparing anion-exchange membranes that would have low resistance, high selectivity, and physical and chemical stability when used in acidic media in a redox energy storage system. Of the twelve systems selected for study, only the system that was based on crosslinked poly-4-vinylpyridinium chloride produced physically strong membranes when equilibrated in l M HCl. The resistivity of the best membrane was 12 ohm-cm, and the transference number for chloride ions was 0.81.

  10. Fe-based semimagnetic semiconductors with two anions

    Microsoft Academic Search

    A. Mycielski; M. Arciszewska; W. Dobrowolski; A. Lusakowski; K. Dybko; R. Szymczak; A. Szadkowski; C. Rigaux; A. Mauger; M. Menant; M. Guillot

    1996-01-01

    (Cd1-xFex)(Te1-ySey) crystals have been studied both theoretically and experimentally. In such a system, a part of Fe2+ ions are located in crystal environments of a lowered symmetry. The energy level structure of these ions is substantially modified with respect to that of the Fe2+ ion in one-anion (ternary) crystal. Regarding magnetic properties, the most essential modification occurs when an Fe2+

  11. Deacidification of a synthetic oil with an anion exchange resin

    Microsoft Academic Search

    Valérie Eychenne; Zéphirin Mouloungui

    1998-01-01

    Esters of trimethylolpropane were prepared by reaction of trimethylolpropane with erucic acid. Unreacted erucic acid was eliminated\\u000a by fixation on an anion exchange resin to produce an oil with a low free fatty acid content. The authors describe the deacidification\\u000a of the reaction product by Lewatit MP500A and MP600 resins in a fixed-bed reactor or in a stirred reactor. The

  12. Biosorption of anionic metal complexes Hui Niu and Bohumil Volesky*

    E-print Network

    Volesky, Bohumil

    such as crab shells sorbed well anionic gold cyanide (AuCN2 - ), selenate (SeO4 2- ), chromate (CrO4 2- ), and vanadate (VO4 3- ) at low pH. Equilibrium biosorption uptakes by acid-washed crab shells were up to 0 sources are the exoskeletons of crabs obtained as waste from sea-food processing.11 Crab shells consist

  13. [Dynamics of ultrastructure changes in sheet plate fiber flax with braking transport assimilate by nitrate-anion].

    PubMed

    Abdrakhimov, F A; Batasheva, S N; Bakirova, G G; Chikov, V I

    2008-01-01

    Changes in leaf mesophyll cell ultrastructure under nitrate feeding into the apoplast of common flax (Linum usitatissimum L.) in the form of 50 mM KNO3 solution were studied. In 30 min after the beginning of nitrate feeding through the transpiration water stream, swelling of mitochondrial and microbodies, clarification of their matrices, and curling of dictyosome discs into annular structures were observed. These events characterized symplastic domain formed by mesophyll, bundle sheath and phloem parenchyma cells, and were not found in companion cell-sieve element complex. Simultaneously, formation of large central vacuoles in companion cells was noted. Restoration of organelle structures in assimilating cells and phloem parenchyma in 1-2 h after treatment was accompanied by enhancement of morphological changes in phloem elements and companion cells and signs of plasmolysis in the mesophyll cells. It was supposed that the two-phase character of changes in leaf organelle ultrastructure and photosynthesis might reflect duality of leaf cell response to nitrate ion. The rapid alterations of the structure can be coupled with direct influence of the anion on cell metabolism and(or) with signal-regulatory functions of oxidized nitrogen forms, while the slower ones reflect the result of suppression of photoassimilate export from leaves by the anion. PMID:18822790

  14. Metabolism of ingested U and Ra.

    PubMed

    Wrenn, M E; Durbin, P W; Howard, B; Lipsztein, J; Rundo, J; Still, E T; Willis, D L

    1985-05-01

    The literature on metabolism of U and Ra for man relevant to deriving drinking water standards has been reviewed and summarized. Radium is well understood, but significant gaps remain in our knowledge about U metabolism. Limits should be based on an equilibrium model where a constant relationship between intake and organ burden is established, using the best and most likely metabolic parameters. For the skeleton we conclude that the best estimate of skeletal burden expressed in days equivalent intake are 25 days for 226Ra, 10 days for 228Ra, and 0.3 days for 224Ra. For long-lived isotopes of U, we chose 11 days, with a range between 1 and 35 days. The committee believes that intake of natural U in water should be limited by considerations of toxicity to the kidney, and we believe that the metabolic model of Spoor and Hursh with a modified gastrointestinal (GI) absorption (1.4%) should be used to infer kidney content. Our review and analysis of the world literature leads us to believe the average human GI absorption of U is most likely 1-2% and is probably reasonably independent of age or the mass of U ingested. Using a safety factor of 50-150, the committee recommends a limit of U in water of 100 micrograms/l in order to limit toxic effects in the kidney. One hundred micrograms/liter is equivalent to 67 pCi/l of long-lived alpha-emitting natural U isotopes. Further research into the distribution of U in the human body is desirable, especially at natural levels in kidney and skeleton, the time-dependent pharmacokinetics of U in animals, the GI absorption of U in man from water and food, toxicological and U distribution studies in animals under conditions of chronic oral U intake, and metabolic model error propagation. PMID:3988524

  15. Lithium cation conducting TDI anion-based ionic liquids.

    PubMed

    Niedzicki, Leszek; Karpierz, Ewelina; Zawadzki, Maciej; Dranka, Maciej; Kasprzyk, Marta; Zalewska, Aldona; Marcinek, Marek; Zachara, Janusz; Doma?ska, Urszula; Wieczorek, W?adys?aw

    2014-06-21

    In this paper we present the synthesis route and electrochemical properties of new class of ionic liquids (ILs) obtained from lithium derivate TDI (4,5-dicyano-2-(trifluoromethyl)imidazolium) anion. ILs synthesized by us were EMImTDI, PMImTDI and BMImTDI, i.e. TDI anion with 1-alkyl-3-methylimidazolium cations, where alkyl meant ethyl, propyl and butyl groups. TDI anion contains fewer fluorine atoms than LiPF6 and thanks to C-F instead of P-F bond, they are less prone to emit fluorine or hydrogen fluoride due to the rise in temperature. Use of IL results in non-flammability, which is making such electrolyte even safer for both application and environment. The thermal stability of synthesized compounds was tested by DSC and TGA and no signal of decomposition was observed up to 250 °C. The LiTDI salt was added to ILs to form complete electrolytes. The structures of tailored ILs with lithium salt were confirmed by X-ray diffraction patterns. The electrolytes showed excellent properties regarding their ionic conductivity (over 3 mS cm(-1) at room temperature after lithium salt addition), lithium cation transference number (over 0.1), low viscosity and broad electrochemical stability window. The ionic conductivity and viscosity measurements of pure ILs are reported for reference. PMID:24803282

  16. Determination of selected anions in water by ion chromatography

    USGS Publications Warehouse

    Fishman, Marvin J.; Pyen, Grace

    1979-01-01

    Ion chromatography is a rapid, sensitive, precise, and accurate method for the determination of major anions in rainwater and surface waters. Simultaneous analyses of a single sample for bromide, chloride, fluoride, nitrate, nitrite, orthophosphate, and sulfate require approximately 20 minutes to obtain a chromatogram. Minimum detection limits range from 0.01 mg/L for fluoride to 0.20 mg/L for chloride and sulfate. Relative standard deviations were less than 9% for all anions except nitrite in Standard Reference Water Samples. Only one reference sample contained nitrite and its concentration was near the minimum level of detection. Similar precision was found for chloride, nitrate, and sulfate at concentrations less than 5 mg/L in rainfall samples. Precision for fluoride ranged from 12 to 22%, but is attributed to the low concentrations in these samples. The other anions were not detected. To determine accuracy of results, several samples were spiked with known concentrations of fluoride, chloride, nitrate, and sulfate; recoveries ranged from 96 to 103%. Known amounts of bromide and phosphate were added, separately, to several other waters, which contained bromide or phosphate. Recovery of added bromide and phosphate ranged from approximately 95 to 104%. No recovery data were obtained for nitrite. Chloride, nitrate, nitrite, orthophosphate, and sulfate, in several samples, were also determined independently by automated colorimetric procedures. An automated ion-selective electrode method was used to determine fluoride. Results are in agreement with results obtained by ion chromatography. (USGS).

  17. Two supramolecular microporous frameworks stabilized by hydroxyl anionic water cluster

    NASA Astrophysics Data System (ADS)

    Jian, Fang Fang; Wang, Jing; Huang, Li Hua; Wang, Xian; Xiao, Hai Lian

    2010-06-01

    Two stable supramolecular microporous framework complexes, from the same [MCl(phen) 2] + (M = Cu, Ni), containing chiral hydroxyl anionic water cluster polymer, were synthesized, and their crystal structures were described. These supramolecular frameworks showed very high stability even if they were heated to 300 °C. Thermal analysis and powder X-ray diffraction results indicated that the water molecules were removed when heated from 150 °C to 300 °C without losing the main crystal framework. Water molecules can be reassembled by exposing the dehydrated form to an atmosphere saturated with water vapor. It indicated that the dehydrated form may be utilized as a potential absorbing agent for water and water vapor. The stable dehydrated form, [MCl(phen) 2][(OH)(H 2O)], suggested the stronger anionic H-bonding and intracluster proton transfer process OH -·H 2O ? H 2O·OH -. The "anion- ? interaction" was found in the crystal lattice of [MCl(phen) 2][(OH)(H 2O)]. This paper reported an example of supramolecular polymer with open channels that could be formed/collapse reversibly upon hydration/dehydration.

  18. Coumarin benzothiazole derivatives as chemosensors for cyanide anions.

    PubMed

    Wang, Kangnan; Liu, Zhiqiang; Guan, Ruifang; Cao, Duxia; Chen, Hongyu; Shan, Yanyan; Wu, Qianqian; Xu, Yongxiao

    2015-06-01

    Four coumarin benzothiazole derivatives, N-(benzo[d]thiazol-2-yl)-2-oxo-2H-chromene-3-carboxamide (1), (Z)-N-(3-methylbenzo[d]thiazol-2(3H)-ylidene)-2-oxo-2H-chromene-3-carboxamide (2), 7-(diethylamino)-N-(benzo[d]thiazol-2-yl)-2-oxo-2H-chromene-3-carboxamide (3) and (Z)-7-(diethylamino)-N-(3-methylbenzo[d]thiazol-2(3H)-ylidene)-2-oxo-2H-chromene-3-carboxamide) (4), have been synthesized. Their crystal structures, photophysical properties in acetonitrile and recognition properties for cyanide anions have been investigated. All the compounds are generally planar, especially compound 1 exhibits perfect planarity with dihedral angle between benzothiazolyl group and coumarin group being only 3.63°. Coumarin benzothiazole compounds 1 and 3 can recognize cyanide anions by Michael addition reaction and compound 3 exhibits color change from yellow to colorless and green fluorescence was quenched completely, which can be observed by naked eye. Coumarin benzothiazolyliden compound 4 can recognize cyanide anions with fluorescence turn-on response based on the copper complex ensemble displacement mechanism. PMID:25766371

  19. Remote bond breaking by interacting temporary anion states.

    PubMed

    Burrow, P D; Gallup, G A

    2006-10-21

    The cross section for bond breaking at the site of a dissociative temporary negative ion state through the dissociative electron attachment process can be considerably enhanced by the presence of a second longer-lived temporary negative ion state elsewhere in the molecule, even one quite remote from the first. In a series of chloroalkenes possessing both C-Cl and C==C bonds separated by various distances, we show that the cross sections are determined by the lifetime of the lower anion state created by the mixing of the anion states of these two moieties, with the wave function's coefficients giving the probability that the electron is located at the dissociative site. Furthermore, the lifetime of the composite anion state can be expressed in terms of these same coefficients and the lifetimes of the unmixed resonances. We also discuss how these results may give insight into the means by which strand breaks are induced in DNA by the attachment of slow electrons. PMID:17059257

  20. Photostability enhancement of anionic natural dye by intercalation into hydrotalcite.

    PubMed

    Kohno, Yoshiumi; Totsuka, Koichi; Ikoma, Shuji; Yoda, Keiko; Shibata, Masashi; Matsushima, Ryoka; Tomita, Yasumasa; Maeda, Yasuhisa; Kobayashi, Kenkichiro

    2009-09-01

    The aim of this study is the improvement of the photostability of several natural anionic dyes, carmine (CM), carthamus yellow (CY), and annatto dye (ANA), by complexation with hydrotalcite. The composite of the dyes and hydrotalcite is prepared by the coprecipitation method. CM is successfully intercalated in the hydrotalcite layer when the amount of introduced CM is large. The photostability of CM in CM/HT composites is superior to the CM adsorbed on silica surface. The effect of the stability enhancement is larger when the amount of introduced CM exceeds 0.23 g/g-host, or when the layer charge density of the hydrotalcite is larger. CY is also stabilized by complexation with hydrotalcite, whereas ANA is not stabilized by complexation with hydrotalcite. The photostability of an anionic natural dye can be improved by intercalation into the hydrotalcite layer, if the dye has a hydrophilic nature and a rather planar structure. The intercalated dye is stabilized by the protection from the attack of the atmospheric oxygen. In addition, contribution of the electrostatic interaction between the positively charged hydrotalcite layer and the intercalated anionic dye is also proposed. PMID:19477459

  1. Divalent-anion salt effects in polyelectrolyte multilayer depositions.

    PubMed

    Dressick, Walter J; Wahl, Kathryn J; Bassim, Nabil D; Stroud, Rhonda M; Petrovykh, Dmitri Y

    2012-11-13

    We systematically investigate the effects of divalent anions on the assembly of polyelectrolyte multilayers by fabricating polystyrene sulfonate (PSS)/polyallylamine hydrochloride (PAH) multilayer films from aqueous solutions containing SO(4)(2-), HPO(4)(2-), or organic dicarboxylate dianions. The chosen concentrations of these anions (i.e., ?0.05 M) allow us to isolate their effects on the assembly process from those of the polyelectrolyte solubility or solution ionic strength (maintained constant at ? = 1.00 M by added NaCl). Compared to a control film prepared from solutions containing only Cl(-) anions, stratified multilayers deposited in the presence of dianions exhibit increased UV absorbance, thickness, and roughness. From the dependence of film properties on the solution concentration of SO(4)(2-) and number of polyelectrolyte layers deposited, we derive a generic model for the PSS/PAH multilayer formation that involves adsorption of PAH aggregates formed in solution via electrostatic interactions of PAH with bridging dianions. Experiments using HPO(4)(2-) and organic dicarboxylate species of varying structure indicate that the separation, rigidity, and angle between the discrete negatively charged sites in the dianion govern the formation of the PAH aggregates, and therefore also the properties of the multilayer film. A universal linear relationship between film UV absorbance and thickness is observed among all dianion types or concentrations, consistent with the model. PMID:23106264

  2. Structure and electronic spectra of the C C6- anion

    NASA Astrophysics Data System (ADS)

    Hammoutene, D.; Hochlaf, M.; Senent, M. L.

    2012-08-01

    Ab initio calculations are employed for determining structures, spectroscopic parameters and transitions to the excited electronic states of the astrophysical relevant C C6- anion, which is a potential intermediate of chemical processes involving carbon chains and polycyclic aromatic hydrocarbons. Calculations confirm the prominent stability of linear carbon chain anions which guarantees their formation. The lowest doublet potential energy surface of C? displays six isomers, whereas in the lowest quartet potential energy surface, a unique minimum energy geometry is found. The most stable form is the linear anion l-C? (X2?u) followed by the c-C?(X2A1')at 9291 cm-1 above in energy, which presents a distorted D3h structure. The other isomers are also located at more than 9000 cm-1 above l-C? (X2?u). For each isomer, a set of spectroscopic parameters including their equilibrium structures, rotational constants at equilibrium, harmonic wavenumbers, dipole moments and electron affinities are predicted. For linear C?, eight electronic states lying below the electron detachment threshold, are computed. Four doublet electronic states, which play important roles in the C? reactivity, lie below 2 eV. Spin-orbit constants for the upper electronic states of l-C? are predicted.

  3. Phosphate Removal by Anion Binding on Functionalized Nanoporous Sorbents

    SciTech Connect

    Chouyyok, Wilaiwan; Wiacek, Robert J.; Pattamakomsan, Kanda; Sangvanich, Thanapon; Grudzien, Rafal M.; Fryxell, Glen E.; Yantasee, Wasanna

    2010-03-26

    Phosphate was captured from aqueous solutions by cationic metal-EDA complexes anchored inside mesoporous silica MCM-41 supports (Cu(II)-EDA-SAMMS and Fe(III)-EDA-SAMMS). Fe-EDA-SAMMS was more effective at capturing phosphate than the Cu-EDA-SAMMS and was further studied for matrix effects (e.g., pH, ionic strength, and competing anions) and sorption performance (e.g., capacity and rate). The adsorption of phosphate was highly pH dependent; it increased with increasing pH from 1.0 to 6.5, and decreased above pH 6.5. The adsorption was affected by high ionic strength (0.1 M of NaCl). In the presence of 1000-fold molar excess of chloride and nitrate anions, phosphate removal by Fe-EDA-SAMMS was not affected. Slight, moderate and large impacts were seen with bicarbonate, sulfate and citrate anions, respectively. The phosphate adsorption data on Fe-EDA-SAMMS agreed well with the Langmuir model with the estimated maximum capacity of 43.3 mg/g. The material displayed rapid sorption rate (99% of phosphate removal within 1 min) and lowering the phosphate content to ~ 10 µg/L of phosphorus, which is lower than the EPA’s established freshwater contaminant level for phosphorous (20 µg/L).

  4. Solubility and transport of cationic and anionic patterned nanoparticles.

    PubMed

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

    2012-01-01

    We analyze bulk diffusion and transport through hydrophobic nanochannels of nanoparticles (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. Ten different charge pattern types including Janus charged-hydrophobic NPs are studied. The cationic NPs are more affected by the patterns 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. The NP-water Coulomb interaction of anionic NPs in the bulk, which are much stronger than the hydrophobic NP-water interactions, are stronger for NPs with higher localized charge, and stronger than in the cationic NPs counterparts. The diffusion and transport of anionic NPs such as proteins and protein charge ladders with the same total charge but different surface charge patterns are slowest for the highest localized charge pattern, which also adsorb strongest onto surfaces. Our model demonstrates the separation (by reverse osmosis, capillary electrophoresis, or chromatography) of cationic NPs, including proteins with equal net charge but different surface charge distributions. PMID:22400574

  5. Solubility and transport of cationic and anionic patterned nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    We analyze bulk diffusion and transport through hydrophobic nanochannels of nanoparticles (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. Ten different charge pattern types including Janus charged-hydrophobic NPs are studied. The cationic NPs are more affected by the patterns 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. The NP-water Coulomb interaction of anionic NPs in the bulk, which are much stronger than the hydrophobic NP-water interactions, are stronger for NPs with higher localized charge, and stronger than in the cationic NPs counterparts. The diffusion and transport of anionic NPs such as proteins and protein charge ladders with the same total charge but different surface charge patterns are slowest for the highest localized charge pattern, which also adsorb strongest onto surfaces. Our model demonstrates the separation (by reverse osmosis, capillary electrophoresis, or chromatography) of cationic NPs, including proteins with equal net charge but different surface charge distributions.

  6. SLC5 Sodium-Anion Cotransporters and Renal Urate Transport

    NASA Astrophysics Data System (ADS)

    Mount, David B.; Kwon, Charles Y.; Plata, Consuelo; Romero, Michael F.; Zandi-Nejad, Kambiz

    2007-04-01

    Renal urate transport plays a key role in determining the concentration of circulating uric acid. The reabsorption of filtered urate by the renal proximal tubule appears to require apical sodium-dependent anion transport and the apical URAT1 urate-anion exchanger, in that sodium-dependent transport of lactate, ketoacids, nicotinate, and pyrazinoate (PZA) increases the intracellular concentration of substrates for the subsequent exchange with luminal urate. We have identified SLC5A8 and SLC5A12 as candidates for the sodium-anion cotransporter that collaborates with URAT1. Both transporters function as sodium-dependent nicotinate/monocarboxylate/PZA transporters. Localization studies reveal serial co-expression of these transporters with URAT1, with Slc5a12 in the early proximal tubule and Slc5a8 in S2 and S3 segments. Renal urate excretion is conceivably affected by changes in the activity of SLC5A8, SLC5A12, and/or URAT1, with implications for the pathogenesis of hyperuricemia, nephrolithiasis, and related disorders.

  7. Process for separating and recovering an anionic dye from an aqueous solution

    DOEpatents

    Rogers, R.; Horwitz, E.P.; Bond, A.H.

    1998-01-13

    A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution. 7 figs.

  8. Process for separating and recovering an anionic dye from an aqueous solution

    DOEpatents

    Rogers, Robin (DeKalb, IL); Horwitz, E. Philip (Naperville, IL); Bond, Andrew H. (Tallahassee, FL)

    1998-01-01

    A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution.

  9. Naked-eye detection of biologically important anions by a new chromogenic azo-azomethine sensor

    NASA Astrophysics Data System (ADS)

    Rezaeian, Khatereh; Khanmohammadi, Hamid

    2014-12-01

    A new chromogenic azo-azomethine sensor, containing active phenolic sites, has been designed and synthesized via condensation reaction of N,N,N?,N?-tetrakis(2-aminoethyl)-2,2-dimethyl propane-1,3-diamine with 1-(3-formyl-4-hydroxyphenylazo)-4-nitrobenzene. The anion recognition ability of the synthesized receptor was evaluated using UV-Vis spectroscopy and 1H NMR technique. The anion recognition studies exhibited that the receptor acts as a sensor for biologically important anions such as F-, AcO- and H2PO4- over other anions. The binding stoichiometry between sensor and anions was found to be 1:2. 1H NMR experiment revealed that sensor recognizes anions via H-bonds and subsequent deprotonation to elicit a vivid color change. Interestingly, the sensory system not only let for the naked eye detection without any spectroscopic instrumentation but also helped to discriminate between anions.

  10. Determination of the dissolved anion composition of ancient lakes from fossil ostracodes.

    USGS Publications Warehouse

    Forester, R.M.

    1986-01-01

    The mineralogy of evaporite and other precipitated minerals has provided traditional sources of information about the major dissolved ion composition of ancient lakes. The paleocompositional resolving power of these methods is generally greatest in high-salinity lakes. Ostracodes live in dilute saline lakes where a species occurrence is determined by the relative proportions of the lake's major dissolved anions, so that each species describes specific areas on an anion trilinear diagram. The upper salinity tolerance of each species depends upon the types of major anions in solution and is therefore anion-specific. Knowledge about both anion and anion-salinity tolerances of an ostracode may ultimately provide a means of estimating absolute anion concentrations in paleolakes. Because ostracodes are common fossils in lake sediments, they provide an important new source of original paleocompositional information suitable for many geologic, climatic, geochemical, and paleontologic studies. -from Author

  11. Heterotypic gap junctions at glutamatergic mixed synapses are abundant in goldfish brain.

    PubMed

    Rash, J E; Kamasawa, N; Vanderpool, K G; Yasumura, T; O'Brien, J; Nannapaneni, S; Pereda, A E; Nagy, J I

    2015-01-29

    Gap junctions provide for direct intercellular electrical and metabolic coupling. The abundance of gap junctions at "large myelinated club ending (LMCE)" synapses on Mauthner cells (M-cells) of the teleost brain provided a convenient model to correlate anatomical and physiological properties of electrical synapses. There, presynaptic action potentials were found to evoke short-latency electrical "pre-potentials" immediately preceding their accompanying glutamate-induced depolarizations, making these the first unambiguously identified "mixed" (i.e., chemical plus electrical) synapses in the vertebrate CNS. We recently showed that gap junctions at these synapses exhibit asymmetric electrical resistance (i.e., electrical rectification), which we correlated with total molecular asymmetry of connexin composition in their apposing gap junction hemiplaques, with connexin35 (Cx35) restricted to axon terminal hemiplaques and connexin34.7 (Cx34.7) restricted to apposing M-cell plasma membranes. We now show that similarly heterotypic neuronal gap junctions are abundant throughout goldfish brain, with labeling exclusively for Cx35 in presynaptic hemiplaques and exclusively for Cx34.7 in postsynaptic hemiplaques. Moreover, the vast majority of these asymmetric gap junctions occur at glutamatergic axon terminals. The widespread distribution of heterotypic gap junctions at glutamatergic mixed synapses throughout goldfish brain and spinal cord implies that pre- vs. postsynaptic asymmetry at electrical synapses evolved early in the chordate lineage. We propose that the advantages of the molecular and functional asymmetry of connexins at electrical synapses that are so prominently expressed in the teleost CNS are unlikely to have been abandoned in higher vertebrates. However, to create asymmetric coupling in mammals, where most gap junctions are composed of connexin36 (Cx36) on both sides, would require some other mechanism, such as differential phosphorylation of connexins on opposite sides of the same gap junction or on asymmetric differences in the complement of their scaffolding and regulatory proteins. PMID:25451276

  12. Targeting Cancer Metabolism

    PubMed Central

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

    2012-01-01

    The understanding that oncogenes can have profound effects on cellular metabolism and the discovery of mutations and alterations in several metabolism-related enzymes (IDH1, IDH2, SDH, FH, 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. Amongst intermediary metabolism enzyme, mutations in succinate dehydrogenase (SDH) occur in gastointestinal stromal tumors and result in a pseudohypoxic metabolic milieu. Fumarate hydratase (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

  13. Organic Anion Transporting Polypeptides in the Hepatic Uptake of PBDE Congeners in Mice

    PubMed Central

    Pacyniak, Erik; Hagenbuch, Bruno; Klaassen, Curtis D.; McKeeman, Lois Lehman; Guo, Grace L.

    2011-01-01

    BDE47, BDE99 and BDE153 are the predominant polybrominated diphenyl ether (PBDE) congeners detected in humans and can induce drug metabolizing enzymes in the liver. We have previously demonstrated that several human liver organic anion transporting polypeptides (humans: OATPs; rodents: Oatps) can transport PBDE congeners. Mice are commonly used to study the toxicity of chemicals like the PBDE congeners. However, the mechanism of the hepatic PBDE uptake in mice is not known. Therefore, the purpose of the current study was to test the hypothesis that BDE47, BDE99, and BDE153 are substrates of mouse hepatic Oatps (Oatp1a1, Oatp1a4, Oatp1b2, and Oatp2b1). We used Human Embryonic Kidney 293 (HEK293) cells transiently expressing individual Oatps and quantified the uptake of BDE47, BDE99, and BDE153. Oatp1a4, Oatp1b2, and Oatp2b1 transported all three PBDE congeners, whereas Oatp1a1 did transport none. Kinetic studies demonstrated that Oatp1a4 and Oatp1b2 transported BDE47 with the greatest affinity, followed by BDE99 and BDE153. In contrast, Oatp2b1 transported all three PBDE congeners with similar affinities. The importance of hepatic Oatps for the liver accumulation of BDE47 was confirmed using Oatp1a4-, and Oatp1b2-null mice. PMID:21884716

  14. Superoxide anion radicals induce IGF-1 resistance through concomitant activation of PTP1B and PTEN

    PubMed Central

    Singh, Karmveer; Maity, Pallab; Krug, Linda; Meyer, Patrick; Treiber, Nicolai; Lucas, Tanja; Basu, Abhijit; Kochanek, Stefan; Wlaschek, Meinhard; Geiger, Hartmut; Scharffetter-Kochanek, Karin

    2015-01-01

    The evolutionarily conserved IGF-1 signalling pathway is associated with longevity, metabolism, tissue homeostasis, and cancer progression. Its regulation relies on the delicate balance between activating kinases and suppressing phosphatases and is still not very well understood. We report here that IGF-1 signalling in vitro and in a murine ageing model in vivo is suppressed in response to accumulation of superoxide anions () in mitochondria, either by chemical inhibition of complex I or by genetic silencing of -dismutating mitochondrial Sod2. The -dependent suppression of IGF-1 signalling resulted in decreased proliferation of murine dermal fibroblasts, affected translation initiation factors and suppressed the expression of ?1(I), ?1(III), and ?2(I) collagen, the hallmarks of skin ageing. Enhanced led to activation of the phosphatases PTP1B and PTEN, which via dephosphorylation of the IGF-1 receptor and phosphatidylinositol 3,4,5-triphosphate dampened IGF-1 signalling. Genetic and pharmacologic inhibition of PTP1B and PTEN abrogated -induced IGF-1 resistance and rescued the ageing skin phenotype. We thus identify previously unreported signature events with , PTP1B, and PTEN as promising targets for drug development to prevent IGF-1 resistance-related pathologies. PMID:25520316

  15. Superoxide anion radicals induce IGF-1 resistance through concomitant activation of PTP1B and PTEN.

    PubMed

    Singh, Karmveer; Maity, Pallab; Krug, Linda; Meyer, Patrick; Treiber, Nicolai; Lucas, Tanja; Basu, Abhijit; Kochanek, Stefan; Wlaschek, Meinhard; Geiger, Hartmut; Scharffetter-Kochanek, Karin

    2015-01-01

    The evolutionarily conserved IGF-1 signalling pathway is associated with longevity, metabolism, tissue homeostasis, and cancer progression. Its regulation relies on the delicate balance between activating kinases and suppressing phosphatases and is still not very well understood. We report here that IGF-1 signalling in vitro and in a murine ageing model in vivo is suppressed in response to accumulation of superoxide anions (O2?-) in mitochondria, either by chemical inhibition of complex I or by genetic silencing of O2?--dismutating mitochondrial Sod2. The O2?--dependent suppression of IGF-1 signalling resulted in decreased proliferation of murine dermal fibroblasts, affected translation initiation factors and suppressed the expression of ?1(I), ?1(III), and ?2(I) collagen, the hallmarks of skin ageing. Enhanced O2?- led to activation of the phosphatases PTP1B and PTEN, which via dephosphorylation of the IGF-1 receptor and phosphatidylinositol 3,4,5-triphosphate dampened IGF-1 signalling. Genetic and pharmacologic inhibition of PTP1B and PTEN abrogated O2?--induced IGF-1 resistance and rescued the ageing skin phenotype. We thus identify previously unreported signature events with O2?-, PTP1B, and PTEN as promising targets for drug development to prevent IGF-1 resistance-related pathologies. PMID:25520316

  16. Sirtuins, Metabolism, and Cancer

    PubMed Central

    Martinez-Pastor, Barbara; Mostoslavsky, Raul

    2011-01-01

    More than a decade ago, sirtuins were discovered as a highly conserved family of NAD+-dependent enzymes that extend lifespan in lower organisms. In mammals, sirtuins are key regulators of stress responses and metabolism, influencing a range of diseases, including diabetes, neurodegeneration, and cancer. In recent years, new functions of sirtuins have been characterized, uncovering the underlying mechanisms of their multifaceted role in metabolism. Here, we specifically review recent progress on the role of sirtuins in DNA repair and energy metabolism, further discussing the implication of sirtuins in the biology of cancer. PMID:22363287

  17. Circadian clocks and metabolism.

    PubMed

    Marcheva, Biliana; Ramsey, Kathryn M; Peek, Clara B; Affinati, Alison; Maury, Eleonore; Bass, Joseph

    2013-01-01

    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

  18. Physiology of Iron Metabolism

    PubMed Central

    Waldvogel-Abramowski, Sophie; Waeber, Gérard; Gassner, Christoph; Buser, Andreas; Frey, Beat M.; Favrat, Bernard; Tissot, Jean-Daniel

    2014-01-01

    Summary 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

  19. Physiology of iron metabolism.

    PubMed

    Waldvogel-Abramowski, Sophie; Waeber, Gérard; Gassner, Christoph; Buser, Andreas; Frey, Beat M; Favrat, Bernard; Tissot, Jean-Daniel

    2014-06-01

    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

  20. 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.

  1. GAPS IN THE GD-1 STAR STREAM

    SciTech Connect

    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

    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.

  2. Halogen bonding of electrophilic bromocarbons with pseudohalide anions.

    PubMed

    Rosokha, Sergiy V; Stern, Charlotte L; Swartz, Alan; Stewart, Rory

    2014-07-01

    UV-Vis measurements showed that the interaction of pseudohalide anions, A(-) (A(-) = N3(-), NCO(-), NCS(-)), with electrophilic bromocarbons, R-Br (R-Br = CBr4, CBr3NO2, CBr3CONH2, CBr3H, CBr3F, CBr3CN or C3Br2F6), in solution results in formation of [R-Br, A(-)] complexes. These associates are characterized by intense absorption bands in the 200-350 nm range showing distinct Mulliken correlation with the frontier (HOMO-LUMO) orbitals' separations of the interacting anion and the R-Br electrophile. X-ray crystallographic studies established the principal structural features of the halogen-bonded associates between bromocarbons and polydentate pseudohalide anions. Specifically, in the (Pr4N)NCO·CBr4, (Pr4N)N3·CBr4 and (Pr4N)NCO·CBr3NO2 co-crystals, bromine substituents of the electrophiles are halogen-bonded with the (C?N or N=N) ?-bonds of the cyanate or azide anions. Co-crystals of CBr4 with (Pr4N)NCS show two modes (C-Br···S-C and C-Br···N?C) of halogen bonding, while tribromoacetamide molecules form C-Br···S-C halogen bonds and N-H···N?C hydrogen bonds with thiocyanate anions. Structures and energetics of the halogen-bonded complexes resulted from the M06-2X/6-311+G(dp) computations of various R-Br-A(-) pairs were consistent with the experimental data. These computations revealed that the variations of the intramolecular (C-Br) and intermolecular (Br···A(-)) bond lengths are correlated with the A(-) ? R-Br charge transfer determined from Natural Bond Orbital analysis. Also, the scrutiny of the structural data indicated that the locations of the intermolecular contacts in these associates are determined primarily by the frontier orbital shapes of the halogen-bonded species. Thus, spectral and structural data point out a significant role of molecular-orbital (charge-transfer) interactions in formation of halogen bonded complexes involving pseudohalides and bromocarbons. PMID:24852189

  3. Vibrationally resolved anion photoelectron spectroscopy of metal clusters

    NASA Astrophysics Data System (ADS)

    Miller, Stephen R.

    Vibrationally resolved anion photoelectron spectroscopy of metal clusters Vibrationally resolved anion photoelectron spectroscopy (APES) and density functional theory (DFT) are applied to the study of structure and reactivity in small metal containing molecules. The studies described fall into two general categories: the study of bare metal clusters and the study of metal/organic ligand reactions. The current lack of spectroscopic data for small, bare gas-phase metal compounds makes the experimental study of such compounds important for understanding structure and bonding in open-shell metallic species. The heteronuclear diatomic anions MCu- (M = Cr, Mo) were prepared in a flowing afterglow ion-molecule reactor, and studied experimentally with APES. Anion and neutral vibrational frequencies and MCu electron affinities were obtained for both systems. The experiments were supplemented by DFT calculations. The combined use of experiment and theory allows for the assignment of both photoelectron spectra, including a reassignment of the CrCu ground state reported in the literature. Similarly, DFT was used to assign the anionic/neutral electronic states observed in the photoelectron spectra of Al3- and Al3O-. The study of partially ligated organometallic complexes offers a means of examining the interactions between metal atoms and individual ligand molecules. DFT was used to assign electronic states observed in the photoelectron spectra of NbC2H2-, NbC4H4 -NbC6H6- and VC6H 6-. Comparison of the NbnHn - (n = 2, 4, 6) spectra (obtained through the reaction of C2 H4 and Nb) with DFT results provides the first direct spectroscopic evidence of the conversion of ethylene to benzene by a gas phase metal atom. Experiments were used to probe the reactivity of Y with C2H 4 in an effort to examine the generality of the metal induced C 2H4 dehydrogenation/cyclization reactions. Some of the key products in the Y reactions were YC2H-, YC 2H2-, and YC6H5 -. However, the results indicate that Y does not mediate benzene formation from ethylene under the experimental conditions employed.

  4. Solvent effects on the vibrational frequencies of the phenolate anion, the para-cresolate anion, and their radicals.

    PubMed

    McDonald, William J; Einarsdóttir, Olöf

    2008-11-13

    The effects of aqueous solvation on the structure and vibrational frequencies of phenol, para-cresol, and their respective radicals are calculated at the B3LYP/6-31+G(d,p) level of theory using the conductor-like polarizable continuum model (C-PCM) alone and in combination with an explicit water molecule H-bonded to the phenolic oxygen. Calculated vibrational frequencies are compared to experimental frequencies obtained in aqueous buffer at high pH. For all models, the C-PCM provides the best overall agreement between theory and experiment at a modest computational effort, as demonstrated by the lowest mean absolute deviations in the computed frequencies. In addition, the C-PCM provides anion Wilson mode 7a (18)O isotope shifts in excellent agreement with experiment and improves agreement between the computed and observed radical Wilson mode 7a (2)H isotope shift. On the basis of a quantitative comparison of the anion and radical normal modes by vibrational projection analysis and total energy decomposition, an alternative criterion for distinguishing the anion and radical Wilson modes 7a and 19a using the relative phasing of the carbon-oxygen and carbon-carbon bond stretches is presented. PMID:18939813

  5. SREBPs: Metabolic Integrators in Physiology and Metabolism

    PubMed Central

    Jeon, Tae-Il; Osborne, Timothy F.

    2011-01-01

    Recent advances have significantly increased our understanding of how sterol regulatory element binding proteins (SREBPs) are regulated at the transcriptional and post-transcriptional levels in response to cellular signaling. The phosphatidyl inositol-3-kinase (PI3K) and SREBP pathways intersect at multiple points and recent insights demonstrate the importance of tight regulation of the PI3K pathway for regulating SREBPs in the adaptation to fluctuating dietary calorie load in the mammalian liver. Additionally, genetic and genome-wide approaches highlight new functions for SREBPs in connecting lipid metabolism with other cellular processes where lipid pathway flux affects physiologic or pathophysiologic adaptation, such as cancer, steatosis and innate immunity. This review focuses on recent advances and new roles for mammalian SREBPs in physiology and metabolism. PMID:22154484

  6. Photonic band gap structure simulator

    DOEpatents

    Chen, Chiping; Shapiro, Michael A.; Smirnova, Evgenya I.; Temkin, Richard J.; Sirigiri, Jagadishwar R.

    2006-10-03

    A system and method for designing photonic band gap structures. The system and method provide a user with the capability to produce a model of a two-dimensional array of conductors corresponding to a unit cell. The model involves a linear equation. Boundary conditions representative of conditions at the boundary of the unit cell are applied to a solution of the Helmholtz equation defined for the unit cell. The linear equation can be approximated by a Hermitian matrix. An eigenvalue of the Helmholtz equation is calculated. One computation approach involves calculating finite differences. The model can include a symmetry element, such as a center of inversion, a rotation axis, and a mirror plane. A graphical user interface is provided for the user's convenience. A display is provided to display to a user the calculated eigenvalue, corresponding to a photonic energy level in the Brilloin zone of the unit cell.

  7. Continuous layer gap plasmon resonators.

    PubMed

    Nielsen, Michael G; Gramotnev, Dmitri K; Pors, Anders; Albrektsen, Ole; Bozhevolnyi, Sergey I

    2011-09-26

    We demonstrate both theoretically and experimentally that a gold nanostrip supported by a thin dielectric (silicon dioxide) film and a gold underlay forms an efficient (Fabry-Perot) resonator for gap surface plasmons. Periodic nanostrip arrays are shown to exhibit strong and narrow resonances with nearly complete absorption and quality factors of ~15-20 in the near-infrared. Two-photon luminescence microscopy measurements reveal intensity enhancement factors of ~120 in the 400-nm-period array of 85-nm-wide gold strips atop a 23-nm-thick silica film at the resonance wavelength of ~770 nm. Excellent resonant characteristics, the simplicity of tuning the resonance wavelength by adjusting the nanostrip width and/or the dielectric film thickness and the ease of fabrication with (only) one lithography step required make the considered plasmonic configuration very attractive for a wide variety of applications, ranging from surface sensing to photovoltaics. PMID:21996871

  8. Generating spectral gaps by geometry

    E-print Network

    Fernando Lledó; Olaf Post

    2005-06-23

    Motivated by the analysis of Schr\\"odinger operators with periodic potentials we consider the following abstract situation: Let $\\Delta_X$ be the Laplacian on a non-compact Riemannian covering manifold $X$ with a discrete isometric group $\\Gamma$ acting on it such that the quotient $X/\\Gamma$ is a compact manifold. We prove the existence of a finite number of spectral gaps for the operator $\\Delta_X$ associated with a suitable class of manifolds $X$ with non-abelian covering transformation groups $\\Gamma$. This result is based on the non-abelian Floquet theory as well as the Min-Max-principle. Groups of type I specify a class of examples satisfying the assumptions of the main theorem.

  9. The influence of anion-pi interactions between multi-atomic anions and pi-acidic ring systems on the self-assembly of coordination compounds

    E-print Network

    Schottel, Brandi Lee

    2009-05-15

    of the ligand. To show that these anion-? interactions were indeed important, reactions of bptz ligand as well with 3,6-bis(2’-pyridyl)-1,2-pyridazine (bppn) with Ag(I) salts were performed to compare the effect that specific anions had on self...

  10. Engineering of metabolic control

    DOEpatents

    Liao, James C.

    2004-03-16

    The invention features a method of producing heterologous molecules in cells under the regulatory control of a metabolite and metabolic flux. The method can enhance the synthesis of heterologous polypeptides and metabolites.

  11. Engineering of metabolic control

    DOEpatents

    Liao, James C.

    2006-10-17

    The invention features a method of producing heterologous molecules in cells under the regulatory control of a metabolite and metabolic flux. The method can enhance the synthesis of heterologous polypeptides and metabolites.

  12. Metabolism. Part III: Lipids.

    ERIC Educational Resources Information Center

    Bodner, George M.

    1986-01-01

    Describes the metabolic processes of complex lipids, including saponification, activation and transport, and the beta-oxidation spiral. Discusses fatty acid degradation in regard to biochemical energy and ketone bodies. (TW)

  13. Endocrine and Metabolic Disorders

    MedlinePLUS

    ... due to endocrine and metabolic disorders varied by sex: 4.0 percent of physician visits made by men were for disorders of endocrine glands other than the thyroid, compared to 3.1 percent of visits made by ...

  14. Metabolic Diseases of Muscle

    MedlinePLUS

    ... disease. 9 Metabolic Diseases of Muscle • ©2011 MDA Lactate dehydrogenase deficiency Also called: Glycogenosis type 11 Onset: ... rash is common, probably because skin cells need lactate dehydrogenase. FAt-PRoCEssing disoRdERs Carnitine deficiency Onset: Childhood ...

  15. Circadian regulation of metabolism.

    PubMed

    Bailey, Shannon M; Udoh, Uduak S; Young, Martin E

    2014-08-01

    In association with sleep-wake and fasting-feeding cycles, organisms experience dramatic oscillations in energetic demands and nutrient supply. It is therefore not surprising that various metabolic parameters, ranging from the activity status of molecular energy sensors to circulating nutrient levels, oscillate in time-of-day-dependent manners. It has become increasingly clear that rhythms in metabolic processes are not simply in response to daily environmental/behavioral influences, but are driven in part by cell autonomous circadian clocks. By synchronizing the cell with its environment, clocks modulate a host of metabolic processes in a temporally appropriate manner. The purpose of this article is to review current understanding of the interplay between circadian clocks and metabolism, in addition to the pathophysiologic consequences of disruption of this molecular mechanism, in terms of cardiometabolic disease development. PMID:24928941

  16. Narrow gap electronegative capacitive discharges

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  17. Narrow gap electronegative capacitive discharges

    SciTech Connect

    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

    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.

  18. The Metabolic Syndrome

    Microsoft Academic Search

    Scott M. Grundy

    \\u000a The National Cholesterol Education Program’s Adult Treatment Panel III (ATP III) report [1] added the metabolic syndrome,\\u000a a multidimensional risk factor for cardiovascular disease (CVD), as a coequal partner of elevated low-density lipoprotein\\u000a (LDL) cholesterol for risk-reduction therapies. Interest in the metabolic syndrome has increased greatly since the publication\\u000a of the ATP III report. There are several aspects to the

  19. Obesity and Metabolic Comorbidities: Environmental Diseases?

    PubMed Central

    Lubrano, Carla; Genovesi, Giuseppe; Specchia, Palma; Costantini, Daniela; Mariani, Stefania; Petrangeli, Elisa; Lenzi, Andrea; Gnessi, Lucio

    2013-01-01

    Obesity and metabolic comorbidities represent increasing health problems. Endocrine disrupting compounds (EDCs) are exogenous agents that change endocrine function and cause adverse health effects. Most EDCs are synthetic chemicals; some are natural food components as phytoestrogens. People are exposed to complex mixtures of chemicals throughout their lives. EDCs impact hormone-dependent metabolic systems and brain function. Laboratory and human studies provide compelling evidence that human chemical contamination can play a role in obesity epidemic. Chemical exposures may increase the risk of obesity by altering the differentiation of adipocytes. EDCs can alter methylation patterns and normal epigenetic programming in cells. Oxidative stress may be induced by many of these chemicals, and accumulating evidence indicates that it plays important roles in the etiology of chronic diseases. The individual sensitivity to chemicals is variable, depending on environment and ability to metabolize hazardous chemicals. A number of genes, especially those representing antioxidant and detoxification pathways, have potential application as biomarkers of risk assessment. The potential health effects of combined exposures make the risk assessment process more complex compared to the assessment of single chemicals. Techniques and methods need to be further developed to fill data gaps and increase the knowledge on harmful exposure combinations. PMID:23577225

  20. National GAP Conference 2007-Discussion Groups Report

    USGS Publications Warehouse

    Ratz, Joan M.; Lamb, Berton Lee

    2010-01-01

    We led two discussion groups during the 2007 National GAP Conference. These discussion groups provided information to help develop a survey of National Gap Analysis Program (GAP) data users. One group discussed technical issues, and the second group discussed the use of GAP data for decisionmaking. Themes emerging from the technical issues group included concerns about data quality, need for information on how to use data, and passive data distribution. The decisionmaking discussion included a wide range of topics including the need to understand presentation of information, the need to connect with and understand users of data, the revision of GAP's mission, and the adaptability of products and data. The decisionmaking group also raised concerns regarding technical issues. One conclusion is that a deep commitment to ongoing information transfer and support is a key component of success for the GAP program.

  1. Interjet Rapidity Gaps in Perturbative QCD

    E-print Network

    Gianluca Oderda; George Sterman

    1999-10-20

    We discuss a formalism in which high-$p_T$ dijet rapidity gaps are identified by energy flow in the interjet region. When the gap energy, $Q_{\\rm gap}$, is sufficiently large, the cross section may be computed from standard factorization theorems. For $p_T\\gg Q_T\\gg\\Lambda_{\\rm QCD}$, this is a two-scale perturbative problem, in which we may resum logarithms of $Q_{\\rm gap}/p_T$. The cross section computed as a function of $Q_{\\rm gap}$ reproduces many of the features of the Tevatron dijet gap data. The factorized cross section gives meaning to the color content of the hard scattering.

  2. Gap Junction Proteins in the Blood-Brain Barrier Control Nutrient-Dependent Reactivation of Drosophila Neural Stem Cells

    PubMed Central

    Spéder, Pauline; Brand, Andrea H.

    2014-01-01

    Summary 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

  3. Abdominal obesity and metabolic syndrome

    Microsoft Academic Search

    Jean-Pierre Després; Isabelle Lemieux

    2006-01-01

    Metabolic syndrome is associated with abdominal obesity, blood lipid disorders, inflammation, insulin resistance or full-blown diabetes, and increased risk of developing cardiovascular disease. Proposed criteria for identifying patients with metabolic syndrome have contributed greatly to preventive medicine, but the value of metabolic syndrome as a scientific concept remains controversial. The presence of metabolic syndrome alone cannot predict global cardiovascular disease

  4. Scaling metabolic rate fluctuations

    PubMed Central

    Labra, Fabio A.; Marquet, Pablo A.; Bozinovic, Francisco

    2007-01-01

    Complex ecological and economic systems show fluctuations in macroscopic quantities such as exchange rates, size of companies or populations that follow non-Gaussian tent-shaped probability distributions of growth rates with power-law decay, which suggests that fluctuations in complex systems may be governed by universal mechanisms, independent of particular details and idiosyncrasies. We propose here that metabolic rate within individual organisms may be considered as an example of an emergent property of a complex system and test the hypothesis that the probability distribution of fluctuations in the metabolic rate of individuals has a “universal” form regardless of body size or taxonomic affiliation. We examined data from 71 individuals belonging to 25 vertebrate species (birds, mammals, and lizards). We report three main results. First, for all these individuals and species, the distribution of metabolic rate fluctuations follows a tent-shaped distribution with power-law decay. Second, the standard deviation of metabolic rate fluctuations decays as a power-law function of both average metabolic rate and body mass, with exponents ?0.352 and ?1/4 respectively. Finally, we find that the distributions of metabolic rate fluctuations for different organisms can all be rescaled to a single parent distribution, supporting the existence of general principles underlying the structure and functioning of individual organisms. PMID:17578913

  5. Metabolic cutis laxa syndromes.

    PubMed

    Mohamed, Miski; Kouwenberg, Dorus; Gardeitchik, Thatjana; Kornak, Uwe; Wevers, Ron A; Morava, Eva

    2011-08-01

    Cutis laxa is a rare skin disorder characterized by wrinkled, redundant, inelastic and sagging skin due to defective synthesis of elastic fibers and other proteins of the extracellular matrix. Wrinkled, inelastic skin occurs in many cases as an acquired condition. Syndromic forms of cutis laxa, however, are caused by diverse genetic defects, mostly coding for structural extracellular matrix proteins. Surprisingly a number of metabolic disorders have been also found to be associated with inherited cutis laxa. Menkes disease was the first metabolic disease reported with old-looking, wrinkled skin. Cutis laxa has recently been found in patients with abnormal glycosylation. The discovery of the COG7 defect in patients with wrinkled, inelastic skin was the first genetic link with the Congenital Disorders of Glycosylation (CDG). Since then several inborn errors of metabolism with cutis laxa have been described with variable severity. These include P5CS, ATP6V0A2-CDG and PYCR1 defects. In spite of the evolving number of cutis laxa-related diseases a large part of the cases remain genetically unsolved. In metabolic cutis laxa syndromes the clinical and laboratory features might partially overlap, however there are some distinct, discriminative features. In this review on metabolic diseases causing cutis laxa we offer a practical approach for the differential diagnosis of metabolic cutis laxa syndromes. PMID:21431621

  6. Bridging epigenetics and metabolism

    PubMed Central

    Phang, James M.; Liu, Wei; Hancock, Chad

    2013-01-01

    Recent research suggests that chromatin-modifying enzymes are metabolic sensors regulating gene expression. Epigenetics is linked to metabolomics in response to the cellular microenvironment. Specific metabolites involved in this sensing mechanism include S-adenosylmethionine, acetyl-CoA, alphaketoglutarate and NAD+. Although the core metabolic pathways involving glucose have been emphasized as the source of these metabolites, the reprogramming of pathways involving non-essential amino acids may also play an important role, especially in cancer. Examples include metabolic pathways for glutamine, serine and glycine. The coupling of these pathways to the intermediates affecting epigenetic regulation occurs by “parametabolic” mechanisms. The metabolism of proline may play a special role in this parametabolic linkage between metabolism and epigenetics. Both proline degradation and biosynthesis are robustly affected by oncogenes or suppressor genes, and they can modulate intermediates involved in epigenetic regulation. A number of mechanisms in a variety of animal species have been described by our laboratory and by others. The challenge we now face is to identify the specific chromatin-modifying enzymes involved in coupling of proline metabolism to altered reprogramming of gene expression. PMID:23422013

  7. Case study on knowledge-management gaps

    Microsoft Academic Search

    Chinho Lin; Jong-Mau Yeh; Shu-Mei Tseng

    2005-01-01

    Purpose – To propose a holistic framework for understanding the “knowledge-management (KM) gap” – illustrating six types of gaps that might occur within KM activities. Design\\/methodology\\/approach – The content-analytical approach with the thematic analysis was implemented in the study. Through an in-depth interview with the top managers of two firms, explores the causes of these gaps and fundamental approaches to

  8. Gaps between jets in hadronic collisions

    Microsoft Academic Search

    O. Kepka; C. Marquet; C. Royon

    2010-01-01

    We propose a model to describe diffractive events in hadron-hadron collisions where a rapidity gap is surrounded by two jets. The hard color-singlet object exchanged in the t-channel and responsible for the rapidity gap is described by the pQCD Balitsky-Fadin-Kuraev-Lipatov Pomeron, including corrections due to next-to-leading logarithms. We allow the rapidity gap to be smaller than the inter-jet rapidity interval,

  9. Four-wave-mixing gap solitons

    SciTech Connect

    Zhang Yanpeng; Wang Zhiguo; Zheng Huaibin; Yuan Chenzhi; Li Changbiao; Lu Keqing [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, Xi'an Jiaotong University, Xi'an 710049 (China); Xiao Min [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

    2010-11-15

    We report an experimental demonstration of generating gap soliton trains in a four-wave-mixing (FWM) signal. Such spatial FWM surfacelike gap soliton trains are induced in a periodically modulated self-defocusing atomic medium by the cross-phase modulation, which can be reshaped under different experimental conditions, such as different atomic densities, nonlinear dispersions, and dressing fields. Controlling spatial gap solitons can have important applications in image memory, processing, and communication.

  10. Transport of conjugated bilirubin and other organic anions in bile: relation to biliary lipid structures.

    PubMed Central

    Tazuma, S; Holzbach, R T

    1987-01-01

    Using gel-permeation chromatography, we studied associative relationships between conjugated bilirubin and various biliary lipid particle species, including lecithin/cholesterol vesicles, mixed-lipid micelles, and simple bile salt micelles. Five other organic anions were comparably studied: phenol red, Evans blue, sulfobromophthalein, rose bengal, and indocyanine green. For compounds of intermediate hydrophobicity, including conjugated bilirubin, the dominant association was with a bile salt/organic anion hybrid particle of dimensions larger than that of a simple pure bile salt micelle. Vesicular association was found to be dominant only for the most hydrophobic organic anions, indocyanine green and rose bengal; conversely, the most hydrophilic anion, phenol red, showed no vesicular association. Accordingly, a strong positive correlation (P less than 0.001) was found between percent vesicular association and degree of hydrophobicity of the organic anion. Alkaline conditions (eluant pH 9) decreased or prevented vesicular hydrophobic interaction with all anions. We conclude that two important particulate mechanisms for transport in bile of conjugated bilirubin and other water-soluble anions are bile salt/organic anion hybrid particles and vesicles. For most organic anions of intermediate hydrophobicity, including conjugated bilirubin, the bile salt/organic anion hybrid particle is the dominant transport vehicle. PMID:3470776

  11. Higher order corrections to Color superconducting gaps

    E-print Network

    Deog Ki Hong; Taekoon Lee; Dong-Pil Min; D. Seo; Chaejun Song

    2003-05-07

    We find a (nonlocal) gauge where the wavefunction renormalization constant does not get any corrections for all momenta in the hard-dense loop approximation. In this gauge, we solve the Schwinger-Dyson equations for the diquark condensate in dense QCD to calculate the Cooper pair gap. We determine not only the exponent but also the prefactor of the gap in a gauge independent way. We find that the higher order corrections increase the gap only by about 1.6 times to the leading order gap at Coulomb gauge.

  12. Undecidability of the Spectral Gap (short version)

    E-print Network

    Cubitt, Toby; Wolf, Michael M

    2015-01-01

    The spectral gap -- the difference in energy between the ground state and the first excited state -- is one of the most important properties of a quantum many-body system. Quantum phase transitions occur when the spectral gap vanishes and the system becomes critical. Much of physics is concerned with understanding the phase diagrams of quantum systems, and some of the most challenging and long-standing open problems in theoretical physics concern the spectral gap, such as the Haldane conjecture that the Heisenberg chain is gapped for integer spin, proving existence of a gapped topological spin liquid phase, or the Yang-Mills gap conjecture (one of the Millennium Prize problems). These problems are all particular cases of the general spectral gap problem: Given a quantum many-body Hamiltonian, is the system it describes gapped or gapless? Here we show that this problem is undecidable, in the same sense as the Halting Problem was proven to be undecidable by Turing. A consequence of this is that the spectral gap...

  13. Gaps between jets in hadronic collisions

    SciTech Connect

    Kepka, O. [IPNP, Faculty of Mathematics and Physics, Charles University, Prague (Czech Republic); Center for Particle Physics, Institute of Physics, Academy of Science, Prague (Czech Republic); Marquet, C. [Physics Department, Theory Unit, CERN, 1211 Geneve 23 (Switzerland); Royon, C. [IRFU/Service de physique des particules, CEA/Saclay, 91191 Gif-sur-Yvette cedex (France)

    2011-02-01

    We propose a model to describe diffractive events in hadron-hadron collisions where a rapidity gap is surrounded by two jets. The hard color-singlet object exchanged in the t-channel and responsible for the rapidity gap is described by the perturbative QCD Balitsky-Fadin-Kuraev-Lipatov Pomeron, including corrections due to next-to-leading logarithms. We allow the rapidity gap to be smaller than the interjet rapidity interval, and the corresponding soft radiation is modeled using the HERWIG Monte Carlo. Our model is able to reproduce all Tevatron data, and allows one to estimate the jet-gap-jet cross section at the LHC.

  14. Rapidity gaps in jet events at DOe

    SciTech Connect

    Brandt, Andrew G. [Fermi National Accelerator Laboratory, P.O. Box 50, Batavia, Illinois 60510 (United States)

    1997-04-20

    Preliminary results from the DOe experiment on jet production with rapidity gaps in pp-bar collisions are presented. A class of dijet events with a forward rapidity gap is observed at center-of-mass energies {radical}(s)=1800 GeV and 630 GeV. The number of events with rapidity gaps at both center-of-mass energies is significantly greater than the expectation from multiplicity fluctuations and is consistent with a hard diffractive process. A class of events with two forward gaps and central dijets is also observed at 1800 GeV. This topology is consistent with hard double pomeron exchange.

  15. The crystalline lens. A system networked by gap junctional intercellular communication.

    PubMed

    Goodenough, D A

    1992-02-01

    The vertebrate eye lens is a solid cyst of cells which grows throughout life by addition of new cells at the surface. The older cells, buried by the newer generations, differentiate into long, prismatic fibers, losing their cellular organelles and filling their cytoplasms with high concentrations of soluble proteins, the crystallins. The long-lived lens fibers are interconnected by gap junctions, both with themselves and with an anterior layer of simple cuboidal epithelial cells at the lens surface. This network of gap junctions joins the lens cells into a syncytium with respect to small molecules, permitting metabolic co-operation: intercellular diffusion of ions, metabolites, and water. In contact with nutrients at the lens surface, the epithelial cells retain their cellular organelles, and are able to provide the metabolic energy to maintain correct ion and metabolite concentrations within the lens fiber cytoplasms, such that the crystallins remain in solution and do not aggregate (cataract). Gap junctions are formed by a family of integral membrane channel-forming proteins called connexins. Gap junctions between lens epithelial cells are composed of a connexin which is common between many different cell types, notably myocardial cells and connective tissue fibroblasts. The gap junctions between epithelial cells and lens fibers have not yet been biochemically characterized. The gap junctions formed between lens fibers are composed of at least two different connexins, one of which has not been detected between other cell types. The unusual physiology and longevity of the lens fibers may require the special set of connexins which are found joining these cells. PMID:1320431

  16. Gap Assessment (FY 13 Update)

    SciTech Connect

    Getman, Dan

    2013-09-30

    To help guide its future data collection efforts, The DOE GTO funded a data gap analysis in FY2012 to identify high potential hydrothermal areas where critical data are needed. This analysis was updated in FY2013 and the resulting datasets are represented by this metadata. The original process was published in FY 2012 and is available here: https://pangea.stanford.edu/ERE/db/GeoConf/papers/SGW/2013/Esposito.pdf Though there are many types of data that can be used for hydrothermal exploration, five types of exploration data were targeted for this analysis. These data types were selected for their regional reconnaissance potential, and include many of the primary exploration techniques currently used by the geothermal industry. The data types include: 1. well data 2. geologic maps 3. fault maps 4. geochemistry data 5. geophysical data To determine data coverage, metadata for exploration data (including data type, data status, and coverage information) were collected and catalogued from nodes on the National Geothermal Data System (NGDS). It is the intention of this analysis that the data be updated from this source in a semi-automated fashion as new datasets are added to the NGDS nodes. In addition to this upload, an online tool was developed to allow all geothermal data providers to access this assessment and to directly add metadata themselves and view the results of the analysis via maps of data coverage in Geothermal Prospector (http://maps.nrel.gov/gt_prospector). A grid of the contiguous U.S. was created with 88,000 10-km by 10-km grid cells, and each cell was populated with the status of data availability corresponding to the five data types. Using these five data coverage maps and the USGS Resource Potential Map, sites were identified for future data collection efforts. These sites signify both that the USGS has indicated high favorability of occurrence of geothermal resources and that data gaps exist. The uploaded data are contained in two data files for each data category. The first file contains the grid and is in the SHP file format (shape file.) Each populated grid cell represents a 10k area within which data is known to exist. The second file is a CSV (comma separated value) file that contains all of the individual layers that intersected with the grid. This CSV can be joined with the map to retrieve a list of datasets that are available at any given site. The attributes in the CSV include: 1. grid_id : The id of the grid cell that the data intersects with 2. title: This represents the name of the WFS service that intersected with this grid cell 3. abstract: This represents the description of the WFS service that intersected with this grid cell 4. gap_type: This represents the category of data availability that these data fall within. As the current processing is pulling data from NGDS, this category universally represents data that are available in the NGDS and are ready for acquisition for analytic purposes. 5. proprietary_type: Whether the data are considered proprietary 6. service_type: The type of service 7. base_url: The service URL

  17. Linking genome-scale metabolic modeling and genome annotation

    PubMed Central

    Blais, Edik M.; Chavali, Arvind K.; Papin, Jason A.

    2014-01-01

    Summary Genome-scale metabolic network reconstructions, assembled from annotated genomes, serve as a platform for integrating data from heterogeneous sources and generating hypotheses for further experimental validation. Implementing constraint-based modeling techniques such as Flux Balance Analysis (FBA) on network reconstructions allow for interrogating metabolism at a systems-level, which aids in identifying and rectifying gaps in knowledge. With genome sequences for various organisms from prokaryotes to eukaryotes becoming increasingly available, a significant bottleneck lies in the structural and functional annotation of these sequences. Using topologically-based and biologically-inspired metabolic network refinement, we can better characterize enzymatic functions present in an organism and link annotation of these functions to candidate transcripts, both steps that can be experimentally validated. PMID:23417799

  18. Mapping photoautotrophic metabolism with isotopically nonstationary 13C flux analysis

    PubMed Central

    Young, Jamey D.; Shastri, Avantika A.; Stephanopoulos, Gregory; Morgan, John A.

    2011-01-01

    Understanding in vivo regulation of photoautotrophic metabolism is important for identifying strategies to improve photosynthetic efficiency or re-route carbon fluxes to desirable end products. We have developed an approach to reconstruct comprehensive flux maps of photoautotrophic metabolism by computational analysis of dynamic isotope labeling measurements and have applied it to determine metabolic pathway fluxes in the cyanobacterium Synechocystis sp. PCC6803. Comparison to a theoretically predicted flux map revealed inefficiencies in photosynthesis due to oxidative pentose phosphate pathway and malic enzyme activity, despite negligible photorespiration. This approach has potential to fill important gaps in our understanding of how carbon and energy flows are systemically regulated in cyanobacteria, plants, and algae. PMID:21907300

  19. Nucleotide sequence of the tobacco (Nicotiana tabacum) anionic peroxidase gene

    SciTech Connect

    Diaz-De-Leon, F.; Klotz, K.L.; Lagrimini, L.M. (Ohio State Univ., Columbus (United States))

    1993-03-01

    Peroxidases have been implicated in numerous physiological processes including lignification (Grisebach, 1981), wound-healing (Espelie et al., 1986), phenol oxidation (Lagrimini, 1991), pathogen defense (Ye et al., 1990), and the regulation of cell elongation through the formation of interchain covalent bonds between various cell wall polymers (Fry, 1986; Goldberg et al., 1986; Bradley et al., 1992). However, a complete description of peroxidase action in vivo is not available because of the vast number of potential substrates and the existence of multiple isoenzymes. The tobacco anionic peroxidase is one of the better-characterized isoenzymes. This enzyme has been shown to oxidize a number of significant plant secondary compounds in vitro including cinnamyl alcohols, phenolic acids, and indole-3-acetic acid (Maeder, 1980; Lagrimini, 1991). A cDNA encoding the enzyme has been obtained, and this enzyme was shown to be expressed at the highest levels in lignifying tissues (xylem and tracheary elements) and also in epidermal tissue (Lagrimini et al., 1987). It was shown at this time that there were four distinct copies of the anionic peroxidase gene in tobacco (Nicotiana tabacum). A tobacco genomic DNA library was constructed in the [lambda]-phase EMBL3, from which two unique peroxidase genes were sequenced. One of these clones, [lambda]POD1, was designated as a pseudogene when the exonic sequences were found to differ from the cDNA sequences by 1%, and several frame shifts in the coding sequences indicated a dysfunctional gene (the authors' unpublished results). The other clone, [lambda]POD3, described in this manuscript, was designated as the functional tobacco anionic peroxidase gene because of 100% homology with the cDNA. Significant structural elements include an AS-2 box indicated in shoot-specific expression (Lam and Chua, 1989), a TATA box, and two intervening sequences. 10 refs., 1 tab.

  20. Tautomeric equilibria of 5-fluorouracil anionic species in water.

    PubMed

    Markova, Nadezhda; Enchev, Venelin; Ivanova, Galya

    2010-12-23

    It has long been postulated that rare tautomeric or ionized forms of nucleic acid bases may play a role in mispair formation. Therefore, ab initio quantum chemical investigations on the tautomeric equilibrium in 5-fluorouracil (5FU) and its anions (deprotonated from N1, AN1, and from N3, AN3) and their tautomeric forms in water were performed. The effect of the water as solvent was introduced using solute-solvent clusters (four water molecules). The influence of the water molecules on the tautomeric reactions between different forms was considered by multiple proton transfer mechanisms. We show that when a water dimer is located in the reaction site between the two pairs of N-H and C?O groups, the assistive effect of the water molecules is strengthened. All calculations of the solute-water complexes were carried out at an MP2 level of theory and supplemented with correction for higher order correlation terms at CCSD(T) level, using the 6-31+G(d,p) basis set. The ab initio calculated frequencies and Raman intensities of 5FU and its anions AN1, AN3, and dianion are in good agreement with the experimental Raman frequencies in aqueous solution at different pH. In order to establish the pH-induced structural transformation in the molecule of 5FU, further (1)H, (19)F, and (13)C NMR spectra in water solution for pH = 6.9-13.8 were acquired and the chemical shift alterations were determined as a function of pH. On the basis of NMR spectroscopic data obtained for 5FU in aqueous solution at alkaline pH, we suggest the existence of a mixture of the anionic tautomeric forms predicted by our theoretical calculations. PMID:21090740