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Sample records for acid sensing ion

  1. Acid-sensing ion channels and migraine

    Directory of Open Access Journals (Sweden)

    Yu-qi KANG

    2015-09-01

    Full Text Available Acid-sensing ion channels (ASICs are ligand-gated ion channels that are activated by extracellular protons (H+, which belong to epithelial sodium channels/degenerin (ENaC/DEG superfamily. ASICs are widely distributed in central nervous system, peripheral nervous system, digestive system and some tumor tissues. Different ASIC subunits play important roles in various pathophysiological processes such as touch, sour taste, learning and memory, including inflammation, ischemic stroke, pain, learning and memory decline, epilepsy, multiple sclerosis (MS, migraine, irritable bowel syndrome and tumor. Research over the last 2 decades has achieved substantial advances in migraine pathophysiology. It is now largely accepted that inflammatory pathways play a key role and three main events seem to take place: cortical spreading depression (CSD, activation of the trigeminovascular system (i.e. dural nociceptors, peripheral and central sensitization of this pain pathway. However, the exact mechanisms that link these three events to each other and to inflammation have so far remained to be studied. This article takes an overview of newly research advances in structure, distribution and the relationship with migraine of ASICs.  DOI: 10.3969/j.issn.1672-6731.2015.09.013

  2. Amino acid-sensing ion channels in plants

    Energy Technology Data Exchange (ETDEWEB)

    Spalding, Edgar P. [Univ. of Wisconsin, Madison, WI (United States)

    2014-08-12

    The title of our project is “Amino acid-sensing ion channels in plants”. Its goals are two-fold: to determine the molecular functions of glutamate receptor-like (GLR) proteins, and to elucidate their biological roles (physiological or developmental) in plants. Here is our final technical report. We were highly successful in two of the three aims, modestly successful in the third.

  3. Acid-sensing ion channels: trafficking and synaptic function

    Directory of Open Access Journals (Sweden)

    Zha Xiang-ming

    2013-01-01

    Full Text Available Abstract Extracellular acidification occurs in the brain with elevated neural activity, increased metabolism, and neuronal injury. This reduction in pH can have profound effects on brain function because pH regulates essentially every single biochemical reaction. Therefore, it is not surprising to see that Nature evolves a family of proteins, the acid-sensing ion channels (ASICs, to sense extracellular pH reduction. ASICs are proton-gated cation channels that are mainly expressed in the nervous system. In recent years, a growing body of literature has shown that acidosis, through activating ASICs, contributes to multiple diseases, including ischemia, multiple sclerosis, and seizures. In addition, ASICs play a key role in fear and anxiety related psychiatric disorders. Several recent reviews have summarized the importance and therapeutic potential of ASICs in neurological diseases, as well as the structure-function relationship of ASICs. However, there is little focused coverage on either the basic biology of ASICs or their contribution to neural plasticity. This review will center on these topics, with an emphasis on the synaptic role of ASICs and molecular mechanisms regulating the spatial distribution and function of these ion channels.

  4. Acid-sensing ion channels: trafficking and synaptic function.

    Science.gov (United States)

    Zha, Xiang-ming

    2013-01-02

    Extracellular acidification occurs in the brain with elevated neural activity, increased metabolism, and neuronal injury. This reduction in pH can have profound effects on brain function because pH regulates essentially every single biochemical reaction. Therefore, it is not surprising to see that Nature evolves a family of proteins, the acid-sensing ion channels (ASICs), to sense extracellular pH reduction. ASICs are proton-gated cation channels that are mainly expressed in the nervous system. In recent years, a growing body of literature has shown that acidosis, through activating ASICs, contributes to multiple diseases, including ischemia, multiple sclerosis, and seizures. In addition, ASICs play a key role in fear and anxiety related psychiatric disorders. Several recent reviews have summarized the importance and therapeutic potential of ASICs in neurological diseases, as well as the structure-function relationship of ASICs. However, there is little focused coverage on either the basic biology of ASICs or their contribution to neural plasticity. This review will center on these topics, with an emphasis on the synaptic role of ASICs and molecular mechanisms regulating the spatial distribution and function of these ion channels.

  5. Acid-sensing ion channels and transient-receptor potential ion channels in zebrafish taste buds.

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    Levanti, M; Randazzo, B; Viña, E; Montalbano, G; Garcia-Suarez, O; Germanà, A; Vega, J A; Abbate, F

    2016-09-01

    Sensory information from the environment is required for life and survival, and it is detected by specialized cells which together make up the sensory system. The fish sensory system includes specialized organs that are able to detect mechanical and chemical stimuli. In particular, taste buds are small organs located on the tongue in terrestrial vertebrates that function in the perception of taste. In fish, taste buds occur on the lips, the flanks, and the caudal (tail) fins of some species and on the barbels of others. In fish taste receptor cells, different classes of ion channels have been detected which, like in mammals, presumably participate in the detection and/or transduction of chemical gustatory signals. However, since some of these ion channels are involved in the detection of additional sensory modalities, it can be hypothesized that taste cells sense stimuli other than those specific for taste. This mini-review summarizes current knowledge on the presence of transient-receptor potential (TRP) and acid-sensing (ASIC) ion channels in the taste buds of teleosts, especially adult zebrafish. Up to now ASIC4, TRPC2, TRPA1, TRPV1 and TRPV4 ion channels have been found in the sensory cells, while ASIC2 was detected in the nerves supplying the taste buds. Copyright © 2016 Elsevier GmbH. All rights reserved.

  6. Acidosis counteracts itch tachyphylaxis to consecutive pruritogen exposure dependent on acid-sensing ion channel 3.

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    Jiang, Yi-Ming; Huang, Chen; Peng, Zhong; Han, Shao-Ling; Li, Wei-Guang; Zhu, Michael Xi; Xu, Tian-Le

    2017-01-01

    Tachyphylaxis of itch refers to a markedly reduced scratching response to consecutive exposures of a pruritogen, a process thought to protect against tissue damage by incessant scratching and to become disrupted in chronic itch. Here, we report that a strong stimulation of the Mas-related G-protein-coupled receptor C11 by its agonist, Ser-Leu-Ile-Gly-Arg-Leu-NH 2 (SL-NH 2 ) or bovine adrenal medulla 8-22 peptide, via subcutaneous injection in mice induces tachyphylaxis to the subsequent application of SL-NH 2 to the same site. Notably, co-application of acid and SL-NH 2 following the initial injection of the pruritogen alone counteracted itch tachyphylaxis by augmenting the scratching behaviors in wild-type but not in acid-sensing ion channel 3-null, animals. Using an activity-dependent silencing strategy, we identified that acid-sensing ion channel 3-mediated itch enhancement mainly occurred via the Mas-related G-protein-coupled receptor C11-responsive sensory neurons. Together, our results indicate that acid-sensing ion channel 3, activated by concomitant acid and certain pruritogens, constitute a novel signaling pathway that counteracts itch tachyphylaxis to successive pruritogenic stimulation, which likely contributes to chronic itch associated with tissue acidosis.

  7. A selectivity filter at the intracellular end of the acid-sensing ion channel pore

    DEFF Research Database (Denmark)

    Lynagh, Timothy; Flood, Emelie; Boiteux, Céline

    2017-01-01

    Increased extracellular proton concentrations during neurotransmission are converted to excitatory sodium influx by acid-sensing ion channels (ASICs). 10-fold sodium/potassium selectivity in ASICs has long been attributed to a central constriction in the channel pore, but experimental verificatio...... at the "GAS belt" in the central constriction. Instead, we identified a band of glutamate and aspartate side chains at the lower end of the pore that enables preferential sodium conduction....

  8. Acid-sensing ion channels contribute to the metaboreceptor component of the exercise pressor reflex

    OpenAIRE

    McCord, Jennifer L.; Tsuchimochi, Hirotsugu; Kaufman, Marc P.

    2009-01-01

    The exercise pressor reflex is evoked by both mechanical and metabolic stimuli arising in contracting skeletal muscle. Recently, the blockade of acid-sensing ion channels (ASICs) with amiloride and A-316567 attenuated the reflex. Moreover, amiloride had no effect on the mechanoreceptor component of the reflex, prompting us to determine whether ASICs contributed to the metaboreceptor component of the exercise pressor reflex. The metaboreceptor component can be assessed by measuring mean arteri...

  9. Hypotonic stimuli enhance proton-gated currents of acid-sensing ion channel-1b

    International Nuclear Information System (INIS)

    Ugawa, Shinya; Ishida, Yusuke; Ueda, Takashi; Yu, Yong; Shimada, Shoichi

    2008-01-01

    Acid-sensing ion channels (ASICs) are strong candidates for mammalian mechanoreceptors. We investigated whether mouse acid-sensing ion channel-1b (ASIC1b) is sensitive to mechanical stimuli using oocyte electrophysiology, because ASIC1b is located in the mechanosensory stereocilia of cochlear hair cells. Hypotonic stimuli that induced membrane stretch of oocytes evoked no significant current in ASIC1b-expressing oocytes at pH 7.5. However, acid (pH 4.0 or 5.0)-evoked currents in the oocytes were substantially enhanced by the hypotonicity, showing mechanosensitivity of ASIC1b and possible mechanogating of the channel in the presence of other components. Interestingly, the ASIC1b channel was permeable to K + (a principal charge carrier for cochlear sensory transduction) and the affinity of the channel for amiloride (IC 50 (inhibition constant) = approximately 48.3 μM) was quite similar to that described for the mouse hair cell mechanotransducer current. Taken together, these data raise the possibility that ASIC1b participates in cochlear mechanoelectrical transduction

  10. Novel Insights into Acid-Sensing Ion Channels: Implications for Degenerative Diseases.

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    Zhou, Ren-Peng; Wu, Xiao-Shan; Wang, Zhi-Sen; Xie, Ya-Ya; Ge, Jin-Fang; Chen, Fei-Hu

    2016-08-01

    Degenerative diseases often strike older adults and are characterized by progressive deterioration of cells, eventually leading to tissue and organ degeneration for which limited effective treatment options are currently available. Acid-sensing ion channels (ASICs), a family of extracellular H(+)-activated ligand-gated ion channels, play critical roles in physiological and pathological conditions. Aberrant activation of ASICs is reported to regulate cell apoptosis, differentiation and autophagy. Accumulating evidence has highlighted a dramatic increase and activation of ASICs in degenerative disorders, including multiple sclerosis, Parkinson's disease, Huntington's disease, intervertebral disc degeneration and arthritis. In this review, we have comprehensively discussed the critical roles of ASICs and their potential utility as therapeutic targets in degenerative diseases.

  11. Identification of acid-sensing ion channels in adenoid cystic carcinomas

    International Nuclear Information System (INIS)

    Ye Jinhai; Gao Jun; Wu Yunong; Hu Yongjie; Zhang Chenping; Xu Tianle

    2007-01-01

    Tissue acidosis is an important feature of tumor. The response of adenoid cystic carcinoma (ACC) cells to acidic solution was studied using whole-cell patch-clamp recording in the current study. An inward, amiloride-sensitive Na + current was identified in cultured ACC-2 cells while not in normal human salivary gland epithelial cells. Electrophysiological and pharmacological properties of the currents suggest that heteromeric acid-sensing ion channels (ASICs) containing 2a and 3 may be responsible for the proton-induced currents in the majority of ACC-2 cells. Consistent with it, analyses of RT-PCR and Western blotting demonstrated the presences of ASIC2a and 3 in ACC-2 cells. Furthermore, we observed the enhanced expression of ASIC2a and 3 in the sample of ACC tissues. These results indicate that the functional expression of ASICs is characteristic feature of ACC cells

  12. Electrocatalytic Activity of Carbonized Nanostructured Polyanilines for Oxidation Reactions: Sensing of Nitrite Ions and Ascorbic Acid

    International Nuclear Information System (INIS)

    Micić, Darko; Šljukić, Biljana; Zujovic, Zoran; Travas-Sejdic, Jadranka; Ćirić-Marjanović, Gordana

    2014-01-01

    Highlights: • Carbonized PANIs prepared from various nanostructured PANI precursors • Electroanalytical performances of carbonized PANIs evaluated using voltammetry • Study of carbonized PANIs physico-chemical properties related to electroactivity • The lowest over-potential for NO 2 − oxidation at c-PANI (+0.87 V vs. SCE) • The lowest over-potential for ascorbic acid oxidation at both c-PANI and c-PANI-SSA - Abstract: A comparative study of the electrocatalytic activity of nitrogen-containing carbon nanomaterials, prepared by the carbonization of nanostructured polyaniline (PANI) salts, for the electrooxidation reactions is presented. Nanostructured PANI salts were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in an aqueous solution in the presence of 5-sulfosalicylic acid (PANI-SSA), 3,5-dinitrosalicylic acid (PANI-DNSA) as well as without added acid (PANI), and subsequently carbonized to c-PANI-SSA, c-PANI-DNSA and c-PANI, respectively. Glassy carbon tip was modified with nanostructured c-PANIs and used for the investigation of sensing of nitrite and ascorbic acid in aqueous solutions as model analytes by linear sweep voltammetry. All three types of the investigated c-PANIs gave excellent response to the nitrite ions and ascorbic acid electrooxidation. The lowest peak potential for nitrite ion oxidation exhibited c-PANI (+0.87 V vs. SCE), and for ascorbic acid oxidation both c-PANI and c-PANI-SSA (ca. + 0.13 V vs. SCE). Electrochemical data were correlated with structural and textural data obtained by Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental and nitrogen sorption analysis

  13. Glioblastoma cancer stem cell lines express functional acid sensing ion channels ASIC1a and ASIC3

    DEFF Research Database (Denmark)

    Tian, Yuemin; Bresenitz, Pia; Reska, Anna

    2017-01-01

    Acidic microenvironment is commonly observed in tumour tissues, including glioblastoma (GBM), the most aggressive and lethal brain tumour in adults. Acid sensing ion channels (ASICs) are neuronal voltage-insensitive sodium channels, which are sensors of extracellular protons. Here we studied...

  14. Acidic pH promotes intervertebral disc degeneration: Acid-sensing ion channel -3 as a potential therapeutic target.

    Science.gov (United States)

    Gilbert, Hamish T J; Hodson, Nathan; Baird, Pauline; Richardson, Stephen M; Hoyland, Judith A

    2016-11-17

    The aetiology of intervertebral disc (IVD) degeneration remains poorly understood. Painful IVD degeneration is associated with an acidic intradiscal pH but the response of NP cells to this aberrant microenvironmental factor remains to be fully characterised. The aim here was to address the hypothesis that acidic pH, similar to that found in degenerate IVDs, leads to the altered cell/functional phenotype observed during IVD degeneration, and to investigate the involvement of acid-sensing ion channel (ASIC) -3 in the response. Human NP cells were treated with a range of pH, from that of a non-degenerate (pH 7.4 and 7.1) through to mildly degenerate (pH 6.8) and severely degenerate IVD (pH 6.5 and 6.2). Increasing acidity of pH caused a decrease in cell proliferation and viability, a shift towards matrix catabolism and increased expression of proinflammatory cytokines and pain-related factors. Acidic pH resulted in an increase in ASIC-3 expression. Importantly, inhibition of ASIC-3 prevented the acidic pH induced proinflammatory and pain-related phenotype in NP cells. Acidic pH causes a catabolic and degenerate phenotype in NP cells which is inhibited by blocking ASIC-3 activity, suggesting that this may be a useful therapeutic target for treatment of IVD degeneration.

  15. ASIC3, an acid-sensing ion channel, is expressed in metaboreceptive sensory neurons

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    Fierro Leonardo

    2005-11-01

    Full Text Available Abstract Background ASIC3, the most sensitive of the acid-sensing ion channels, depolarizes certain rat sensory neurons when lactic acid appears in the extracellular medium. Two functions have been proposed for it: 1 ASIC3 might trigger ischemic pain in heart and muscle; 2 it might contribute to some forms of touch mechanosensation. Here, we used immunocytochemistry, retrograde labelling, and electrophysiology to ask whether the distribution of ASIC3 in rat sensory neurons is consistent with either of these hypotheses. Results Less than half (40% of dorsal root ganglion sensory neurons react with anti-ASIC3, and the population is heterogeneous. They vary widely in cell diameter and express different growth factor receptors: 68% express TrkA, the receptor for nerve growth factor, and 25% express TrkC, the NT3 growth factor receptor. Consistent with a role in muscle nociception, small ( Conclusion Our data indicates that: 1 ASIC3 is expressed in a restricted population of nociceptors and probably in some non-nociceptors; 2 co-expression of ASIC3 and CGRP, and the absence of P2X3, are distinguishing properties of a class of sensory neurons, some of which innervate blood vessels. We suggest that these latter afferents may be muscle metaboreceptors, neurons that sense the metabolic state of muscle and can trigger pain when there is insufficient oxygen.

  16. Molecular basis of inhibition of acid sensing ion channel 1A by diminazene.

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    Aram J Krauson

    Full Text Available Acid-sensing ion channels (ASICs are trimeric proton-gated cation permeable ion channels expressed primarily in neurons. Here we employed site-directed mutagenesis and electrophysiology to investigate the mechanism of inhibition of ASIC1a by diminazene. This compound inhibits mouse ASIC1a with a half-maximal inhibitory concentration (IC50 of 2.4 μM. At first, we examined whether neutralizing mutations of Glu79 and Glu416 alter diminazene block. These residues form a hexagonal array in the lower palm domain that was previously shown to contribute to pore opening in response to extracellular acidification. Significantly, single Gln substitutions at positions 79 and 416 in ASIC1a reduced diminazene apparent affinity by 6-7 fold. This result suggests that diminazene inhibits ASIC1a in part by limiting conformational rearrangement in the lower palm domain. Because diminazene is charged at physiological pHs, we assessed whether it inhibits ASIC1a by blocking the ion channel pore. Consistent with the notion that diminazene binds to a site within the membrane electric field, diminazene block showed a strong dependence with the membrane potential. Moreover, a Gly to Ala mutation at position 438, in the ion conduction pathway of ASIC1a, increased diminazene IC50 by one order of magnitude and eliminated the voltage dependence of block. Taken together, our results indicate that the inhibition of ASIC1a by diminazene involves both allosteric modulation and blocking of ion flow through the conduction pathway. Our findings provide a foundation for the development of more selective and potent ASIC pore blockers.

  17. Heart failure induces changes in acid-sensing ion channels in sensory neurons innervating skeletal muscle.

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    Gibbons, David D; Kutschke, William J; Weiss, Robert M; Benson, Christopher J

    2015-10-15

    Heart failure is associated with diminished exercise capacity, which is driven, in part, by alterations in exercise-induced autonomic reflexes triggered by skeletal muscle sensory neurons (afferents). These overactive reflexes may also contribute to the chronic state of sympathetic excitation, which is a major contributor to the morbidity and mortality of heart failure. Acid-sensing ion channels (ASICs) are highly expressed in muscle afferents where they sense metabolic changes associated with ischaemia and exercise, and contribute to the metabolic component of these reflexes. Therefore, we tested if ASICs within muscle afferents are altered in heart failure. We used whole-cell patch clamp to study the electrophysiological properties of acid-evoked currents in isolated, labelled muscle afferent neurons from control and heart failure (induced by myocardial infarction) mice. We found that the percentage of muscle afferents that displayed ASIC-like currents, the current amplitudes, and the pH dose-response relationships were not altered in mice with heart failure. On the other hand, the biophysical properties of ASIC-like currents were significantly different in a subpopulation of cells (40%) from heart failure mice. This population displayed diminished pH sensitivity, altered desensitization kinetics, and very fast recovery from desensitization. These unique properties define these channels within this subpopulation of muscle afferents as being heteromeric channels composed of ASIC2a and -3 subunits. Heart failure induced a shift in the subunit composition of ASICs within muscle afferents, which significantly altered their pH sensing characteristics. These results might, in part, contribute to the changes in exercise-mediated reflexes that are associated with heart failure. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  18. Naked mole-rat acid-sensing ion channel 3 forms nonfunctional homomers, but functional heteromers.

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    Schuhmacher, Laura-Nadine; Callejo, Gerard; Srivats, Shyam; Smith, Ewan St John

    2018-02-02

    Acid-sensing ion channels (ASICs) form both homotrimeric and heterotrimeric ion channels that are activated by extracellular protons and are involved in a wide range of physiological and pathophysiological processes, including pain and anxiety. ASIC proteins can form both homotrimeric and heterotrimeric ion channels. The ASIC3 subunit has been shown to be of particular importance in the peripheral nervous system with pharmacological and genetic manipulations demonstrating a role in pain. Naked mole-rats, despite having functional ASICs, are insensitive to acid as a noxious stimulus and show diminished avoidance of acidic fumes, ammonia, and carbon dioxide. Here we cloned naked mole-rat ASIC3 (nmrASIC3) and used a cell-surface biotinylation assay to demonstrate that it traffics to the plasma membrane, but using whole-cell patch clamp electrophysiology we observed that nmrASIC3 is insensitive to both protons and the non-proton ASIC3 agonist 2-guanidine-4-methylquinazoline. However, in line with previous reports of ASIC3 mRNA expression in dorsal root ganglia neurons, we found that the ASIC3 antagonist APETx2 reversibly inhibits ASIC-like currents in naked mole-rat dorsal root ganglia neurons. We further show that like the proton-insensitive ASIC2b and ASIC4, nmrASIC3 forms functional, proton-sensitive heteromers with other ASIC subunits. An amino acid alignment of ASIC3s between 9 relevant rodent species and human identified unique sequence differences that might underlie the proton insensitivity of nmrASIC3. However, introducing nmrASIC3 differences into rat ASIC3 (rASIC3) produced only minor differences in channel function, and replacing the nmrASIC3 sequence with that of rASIC3 did not produce a proton-sensitive ion channel. Our observation that nmrASIC3 forms nonfunctional homomers may reflect a further adaptation of the naked mole-rat to living in an environment with high-carbon dioxide levels. © 2018 by The American Society for Biochemistry and Molecular

  19. Deactivation kinetics of acid-sensing ion channel 1a are strongly pH-sensitive.

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    MacLean, David M; Jayaraman, Vasanthi

    2017-03-21

    Acid-sensing ion channels (ASICs) are trimeric cation-selective ion channels activated by protons in the physiological range. Recent reports have revealed that postsynaptically localized ASICs contribute to the excitatory postsynaptic current by responding to the transient acidification of the synaptic cleft that accompanies neurotransmission. In response to such brief acidic transients, both recombinant and native ASICs show extremely rapid deactivation in outside-out patches when jumping from a pH 5 stimulus to a single resting pH of 8. Given that the resting pH of the synaptic cleft is highly dynamic and depends on recent synaptic activity, we explored the kinetics of ASIC1a and 1a/2a heteromers to such brief pH transients over a wider [H + ] range to approximate neuronal conditions better. Surprisingly, the deactivation of ASICs was steeply dependent on the pH, spanning nearly three orders of magnitude from extremely fast (pH 8 to very slow (>300 ms) at pH 7. This study provides an example of a ligand-gated ion channel whose deactivation is sensitive to agonist concentrations that do not directly activate the receptor. Kinetic simulations and further mutagenesis provide evidence that ASICs show such steeply agonist-dependent deactivation because of strong cooperativity in proton binding. This capacity to signal across such a large synaptically relevant bandwidth enhances the response to small-amplitude acidifications likely to occur at the cleft and may provide ASICs with the ability to shape activity in response to the recent history of the synapse.

  20. Blockade of acid sensing ion channels attenuates the exercise pressor reflex in cats.

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    Hayes, Shawn G; Kindig, Angela E; Kaufman, Marc P

    2007-06-15

    Although thin fibre muscle afferents possess acid sensing ion channels (ASICs), their contribution to the exercise pressor reflex is not known. This lack of information is partly attributable to the fact that there is no known selective in vivo antagonist for ASICs. Although amiloride has been shown to antagonize ASICs, it also has been shown to antagonize voltage-gated sodium channels, thereby impairing impulse conduction in sensory nerves. Our aim was to test the hypothesis that lactic acid accumulation in exercising muscle acted on ASICs located on thin fibre muscle afferents to evoke the metabolic component of the exercise pressor reflex. To test this hypothesis, we determined in decerebrate cats if amiloride attenuated the pressor and cardioaccelerator responses to static contraction, to tendon stretch and to arterial injections of lactic acid and capsaicin. We found a dose of amiloride (0.5 microg kg(-1); i.a.) that attenuated the pressor and cardioaccelerator responses to both contraction and lactic acid injection, but had no effect on the responses to stretch and capsaicin. A higher dose of amiloride (5 microg kg(-1), i.a.) not only blocked the pressor and cardioaccelerator responses to lactic acid and contraction, but also attenuated the responses to stretch and to capsaicin, manoeuvers in which ASICs probably play no significant role. In addition, we found that the low dose of amiloride (0.5 microg kg(-1)) had no effect on the responses of muscle spindles to tendon stretch and to succinylcholine, whereas the high dose (5 microg kg(-1)) attenuated the responses to both. Our data suggest the low dose of amiloride used in our experiments selectively blocked ASICs, whereas the high dose blocked ASICs and impulse conduction in muscle afferents. We conclude that ASICs play a role in the metabolic component of the exercise pressor reflex.

  1. Acid-sensing ion channels (ASICs) in the taste buds of adult zebrafish.

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    Viña, E; Parisi, V; Cabo, R; Laurà, R; López-Velasco, S; López-Muñiz, A; García-Suárez, O; Germanà, A; Vega, J A

    2013-03-01

    In detecting chemical properties of food, different molecules and ion channels are involved including members of the acid-sensing ion channels (ASICs) family. Consistently ASICs are present in sensory cells of taste buds of mammals. In the present study the presence of ASICs (ASIC1, ASIC2, ASIC3 and ASIC4) was investigated in the taste buds of adult zebrafish (zASICs) using Western blot and immunohistochemistry. zASIC1 and zASIC3 were regularly absent from taste buds, whereas faint zASIC2 and robust zASIC4 immunoreactivities were detected in sensory cells. Moreover, zASIC2 also immunolabelled nerves supplying taste buds. The present results demonstrate for the first time the presence of zASICs in taste buds of teleosts, with different patterns to that occurring in mammals, probably due to the function of taste buds in aquatic environment and feeding. Nevertheless, the role of zASICs in taste remains to be demonstrated. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  2. Acid-sensing ion channel 2 (asic 2) and trkb interrelationships within the intervertebral disc.

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    Cuesta, Antonio; Viña, Eliseo; Cabo, Roberto; Vázquez, Gorka; Cobo, Ramón; García-Suárez, Olivia; García-Cosamalón, José; Vega, José A

    2015-01-01

    The cells of the intervertebral disc (IVD) have an unusual acidic and hyperosmotic microenvironment. They express acid-sensing ion channels (ASICs), gated by extracellular protons and mechanical forces, as well as neurotrophins and their signalling receptors. In the nervous tissues some neurotrophins regulate the expression of ASICs. The expression of ASIC2 and TrkB in human normal and degenerated IVD was assessed using quantitative-PCR, Western blot, and immunohistochemistry. Moreover, we investigated immunohistochemically the expression of ASIC2 in the IVD of TrkB-deficient mice. ASIC2 and TrkB mRNAs were found in normal human IVD and both increased significantly in degenerated IVD. ASIC2 and TrkB proteins were also found co-localized in a variable percentage of cells, being significantly higher in degenerated IVD than in controls. The murine IVD displayed ASIC2 immunoreactivity which was absent in the IVD of TrkB-deficient mice. Present results demonstrate the occurrence of ASIC2 and TrkB in the human IVD, and the increased expression of both in pathological IVD suggest their involvement in IVD degeneration. These data also suggest that TrkB-ligands might be involved in the regulation of ASIC2 expression, and therefore in mechanisms by which the IVD cells accommodate to low pH and hypertonicity.

  3. Expression and activity of acid-sensing ion channels in the mouse anterior pituitary.

    Directory of Open Access Journals (Sweden)

    Jianyang Du

    Full Text Available Acid sensing ion channels (ASICs are proton-gated cation channels that are expressed in the nervous system and play an important role in fear learning and memory. The function of ASICs in the pituitary, an endocrine gland that contributes to emotions, is unknown. We sought to investigate which ASIC subunits were present in the pituitary and found mRNA expression for all ASIC isoforms, including ASIC1a, ASIC1b, ASIC2a, ASIC2b, ASIC3 and ASIC4. We also observed acid-evoked ASIC-like currents in isolated anterior pituitary cells that were absent in mice lacking ASIC1a. The biophysical properties and the responses to PcTx1, amiloride, Ca2+ and Zn2+ suggested that ASIC currents were mediated predominantly by heteromultimeric channels that contained ASIC1a and ASIC2a or ASIC2b. ASIC currents were also sensitive to FMRFamide (Phe-Met-Arg-Phe amide, suggesting that FMRFamide-like compounds might endogenously regulate pituitary ASICs. To determine whether ASICs might regulate pituitary cell function, we applied low pH and found that it increased the intracellular Ca2+ concentration. These data suggest that ASIC channels are present and functionally active in anterior pituitary cells and may therefore influence their function.

  4. Acid-Sensing Ion Channels as Potential Pharmacological Targets in Peripheral and Central Nervous System Diseases.

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    Radu, Beatrice Mihaela; Banciu, Adela; Banciu, Daniel Dumitru; Radu, Mihai

    2016-01-01

    Acid-sensing ion channels (ASICs) are widely expressed in the body and represent good sensors for detecting protons. The pH drop in the nervous system is equivalent to ischemia and acidosis, and ASICs are very good detectors in discriminating slight changes in acidity. ASICs are important pharmacological targets being involved in a variety of pathophysiological processes affecting both the peripheral nervous system (e.g., peripheral pain, diabetic neuropathy) and the central nervous system (e.g., stroke, epilepsy, migraine, anxiety, fear, depression, neurodegenerative diseases, etc.). This review discusses the role played by ASICs in different pathologies and the pharmacological agents acting on ASICs that might represent promising drugs. As the majority of above-mentioned pathologies involve not only neuronal dysfunctions but also microvascular alterations, in the next future, ASICs may be also considered as potential pharmacological targets at the vasculature level. Perspectives and limitations in the use of ASICs antagonists and modulators as pharmaceutical agents are also discussed. © 2016 Elsevier Inc. All rights reserved.

  5. Endogenous Isoquinoline Alkaloids Agonists of Acid-Sensing Ion Channel Type 3

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    Dmitry I. Osmakov

    2017-09-01

    Full Text Available Acid-sensing ion channels (ASICs ASIC3 expressed mainly in peripheral sensory neurons play an important role in pain perception and inflammation development. In response to acidic stimuli, they can generate a unique biphasic current. At physiological pH 7.4, human ASIC3 isoform (hASIC3 is desensitized and able to generate only a sustained current. We found endogenous isoquinoline alkaloids (EIAs, which restore hASIC3 from desensitization and recover the transient component of the current. Similarly, rat ASIC3 isoform (rASIC3 can also be restored from desensitization (at pH < 7.0 by EIAs with the same potency. At physiological pH and above, EIAs at high concentrations were able to effectively activate hASIC3 and rASIC3. Thus, we found first endogenous agonists of ASIC3 channels that could both activate and prevent or reverse desensitization of the channel. The decrease of EIA levels could be suggested as a novel therapeutic strategy for treatment of pain and inflammation.

  6. A heteromeric Texas coral snake toxin targets acid-sensing ion channels to produce pain.

    Science.gov (United States)

    Bohlen, Christopher J; Chesler, Alexander T; Sharif-Naeini, Reza; Medzihradszky, Katalin F; Zhou, Sharleen; King, David; Sánchez, Elda E; Burlingame, Alma L; Basbaum, Allan I; Julius, David

    2011-11-16

    Natural products that elicit discomfort or pain represent invaluable tools for probing molecular mechanisms underlying pain sensation. Plant-derived irritants have predominated in this regard, but animal venoms have also evolved to avert predators by targeting neurons and receptors whose activation produces noxious sensations. As such, venoms provide a rich and varied source of small molecule and protein pharmacophores that can be exploited to characterize and manipulate key components of the pain-signalling pathway. With this in mind, here we perform an unbiased in vitro screen to identify snake venoms capable of activating somatosensory neurons. Venom from the Texas coral snake (Micrurus tener tener), whose bite produces intense and unremitting pain, excites a large cohort of sensory neurons. The purified active species (MitTx) consists of a heteromeric complex between Kunitz- and phospholipase-A2-like proteins that together function as a potent, persistent and selective agonist for acid-sensing ion channels (ASICs), showing equal or greater efficacy compared with acidic pH. MitTx is highly selective for the ASIC1 subtype at neutral pH; under more acidic conditions (pH 100-fold) proton-evoked activation of ASIC2a channels. These observations raise the possibility that ASIC channels function as coincidence detectors for extracellular protons and other, as yet unidentified, endogenous factors. Purified MitTx elicits robust pain-related behaviour in mice by activation of ASIC1 channels on capsaicin-sensitive nerve fibres. These findings reveal a mechanism whereby snake venoms produce pain, and highlight an unexpected contribution of ASIC1 channels to nociception. © 2011 Macmillan Publishers Limited. All rights reserved

  7. Functional modifications of acid-sensing ion channels by ligand-gated chloride channels.

    Directory of Open Access Journals (Sweden)

    Xuanmao Chen

    Full Text Available Together, acid-sensing ion channels (ASICs and epithelial sodium channels (ENaC constitute the majority of voltage-independent sodium channels in mammals. ENaC is regulated by a chloride channel, the cystic fibrosis transmembrane conductance regulator (CFTR. Here we show that ASICs were reversibly inhibited by activation of GABA(A receptors in murine hippocampal neurons. This inhibition of ASICs required opening of the chloride channels but occurred with both outward and inward GABA(A receptor-mediated currents. Moreover, activation of the GABA(A receptors modified the pharmacological features and kinetic properties of the ASIC currents, including the time course of activation, desensitization and deactivation. Modification of ASICs by open GABA(A receptors was also observed in both nucleated patches and outside-out patches excised from hippocampal neurons. Interestingly, ASICs and GABA(A receptors interacted to regulate synaptic plasticity in CA1 hippocampal slices. The activation of glycine receptors, which are similar to GABA(A receptors, also modified ASICs in spinal neurons. We conclude that GABA(A receptors and glycine receptors modify ASICs in neurons through mechanisms that require the opening of chloride channels.

  8. Role of acid-sensing ion channels in hypoxia- and hypercapnia-induced ventilatory responses.

    Directory of Open Access Journals (Sweden)

    Neil D Detweiler

    Full Text Available Previous reports indicate roles for acid-sensing ion channels (ASICs in both peripheral and central chemoreception, but the contributions of ASICs to ventilatory drive in conscious, unrestrained animals remain largely unknown. We tested the hypotheses that ASICs contribute to hypoxic- and hypercapnic-ventilatory responses. Blood samples taken from conscious, unrestrained mice chronically instrumented with femoral artery catheters were used to assess arterial O2, CO2, and pH levels during exposure to inspired gas mixtures designed to cause isocapnic hypoxemia or hypercapnia. Whole-body plethysmography was used to monitor ventilatory parameters in conscious, unrestrained ASIC1, ASIC2, or ASIC3 knockout (-/- and wild-type (WT mice at baseline, during isocapnic hypoxemia and during hypercapnia. Hypercapnia increased respiratory frequency, tidal volume, and minute ventilation in all groups of mice, but there were no differences between ASIC1-/-, ASIC2-/-, or ASIC3-/- and WT. Isocapnic hypoxemia also increased respiratory frequency, tidal volume, and minute ventilation in all groups of mice. Minute ventilation in ASIC2-/- mice during isocapnic hypoxemia was significantly lower compared to WT, but there were no differences in the responses to isocapnic hypoxemia between ASIC1-/- or ASIC3-/- compared to WT. Surprisingly, these findings show that loss of individual ASIC subunits does not substantially alter hypercapnic or hypoxic ventilatory responses.

  9. Acute stress enhances learning and memory by activating acid-sensing ion channels in rats.

    Science.gov (United States)

    Ye, Shunjie; Yang, Rong; Xiong, Qiuju; Yang, Youhua; Zhou, Lianying; Gong, Yeli; Li, Changlei; Ding, Zhenhan; Ye, Guohai; Xiong, Zhe

    2018-04-15

    Acute stress has been shown to enhance learning and memory ability, predominantly through the action of corticosteroid stress hormones. However, the valuable targets for promoting learning and memory induced by acute stress and the underlying molecular mechanisms remain unclear. Acid-sensing ion channels (ASICs) play an important role in central neuronal systems and involves in depression, synaptic plasticity and learning and memory. In the current study, we used a combination of electrophysiological and behavioral approaches in an effort to explore the effects of acute stress on ASICs. We found that corticosterone (CORT) induced by acute stress caused a potentiation of ASICs current via glucocorticoid receptors (GRs) not mineralocorticoid receptors (MRs). Meanwhile, CORT did not produce an increase of ASICs current by pretreated with GF109203X, an antagonist of protein kinase C (PKC), whereas CORT did result in a markedly enhancement of ASICs current by bryostatin 1, an agonist of PKC, suggesting that potentiation of ASICs function may be depended on PKC activating. More importantly, an antagonist of ASICs, amiloride (10 μM) reduced the performance of learning and memory induced by acute stress, which is further suggesting that ASICs as the key components involves in cognitive processes induced by acute stress. These results indicate that acute stress causes the enhancement of ASICs function by activating PKC signaling pathway, which leads to potentiated learning and memory. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Acid sensing ion channel 1 in lateral hypothalamus contributes to breathing control.

    Directory of Open Access Journals (Sweden)

    Nana Song

    Full Text Available Acid-sensing ion channels (ASICs are present in neurons and may contribute to chemoreception. Among six subunits of ASICs, ASIC1 is mainly expressed in the central nervous system. Recently, multiple sites in the brain including the lateral hypothalamus (LH have been found to be sensitive to extracellular acidification. Since LH contains orexin neurons and innervates the medulla respiratory center, we hypothesize that ASIC1 is expressed on the orexin neuron and contributes to acid-induced increase in respiratory drive. To test this hypothesis, we used double immunofluorescence to determine whether ASIC1 is expressed on orexin neurons in the LH, and assessed integrated phrenic nerve discharge (iPND in intact rats in response to acidification of the LH. We found that ASIC1 was co-localized with orexinA in the LH. Microinjection of acidified artificial cerebrospinal fluid increased the amplitude of iPND by 70% (pH 7.4 v.s. pH 6.5:1.05±0.12 v.s. 1.70±0.10, n = 6, P<0.001 and increased the respiratory drive (peak amplitude of iPND/inspiratory time, PA/Ti by 40% (1.10±0.23 v.s. 1.50±0.38, P<0.05. This stimulatory effect was abolished by blocking ASIC1 with a nonselective inhibitor (amiloride 10 mM, a selective inhibitor (PcTX1, 10 nM or by damaging orexin neurons in the LH. Current results support our hypothesis that the orexin neuron in the LH can exert an excitation on respiration via ASIC1 during local acidosis. Since central acidification is involved in breathing dysfunction in a variety of pulmonary diseases, understanding its underlying mechanism may improve patient management.

  11. Acid sensing ion channel (ASIC) inhibitors exhibit anxiolytic-like activity in preclinical pharmacological models.

    Science.gov (United States)

    Dwyer, Jason M; Rizzo, Stacey J Sukoff; Neal, Sarah J; Lin, Qian; Jow, Flora; Arias, Robert L; Rosenzweig-Lipson, Sharon; Dunlop, John; Beyer, Chad E

    2009-03-01

    Acid sensing ion channels (ASICs) are proton-gated ion channels located in the central and peripheral nervous systems. Of particular interest is ASIC1a, which is located in areas associated with fear and anxiety behaviors. Recent reports suggest a role for ASIC1a in preclinical models of fear conditioning and anxiety. The present experiments evaluated various ASIC inhibitors in preclinical models of autonomic and behavioral parameters of anxiety. In addition, neurochemical studies evaluated the effects of an ASIC inhibitor (A-317567) on neurotransmitter levels in the amygdala. In electrophysiological studies using hippocampal primary neuronal cultures, three ASIC inhibitors (PcTX-1, A-317567, and amiloride) produced concentration-dependent inhibition of acid-evoked currents. In the stress-induced hyperthermia model, acute administration of psalmotoxin 1 (PcTX-1; 10-56 ng, i.c.v.), A-317567 (0.1-1.0 mg/kg, i.p.), and amiloride (10-100 mg/kg, i.p.) prevented stress-induced elevations in core body temperature. In the four-plate test, acute treatment with PcTX-1 (10-56 ng, i.c.v.) and A-317567 (0.01-0.1 mg/kg, i.p.), but not amiloride (3-100 mg/kg, i.p.), produced dose-dependent and significant increases in the number of punished crossings relative to vehicle-treated animals. Additionally, PcTX-1 (56-178 ng, i.c.v.), A-317567 (0.1-10 mg/kg, i.p.), and amiloride (10-100 mg/kg, i.p.) lacked significant anxiolytic-like activity in the elevated zero maze. In neurochemical studies, an infusion of A-317567 (100 microM) into the amygdala significantly elevated the extracellular levels of GABA, but not glutamate, in this brain region. These findings demonstrate that ASIC inhibition produces anxiolytic-like effects in some behavioral models and indicate a potential role for GABAergic mechanisms to underlie these anxiolytic-like effects.

  12. Acid-sensing ion and epithelial sodium channels do not contribute to the mechanoreceptor component of the exercise pressor reflex

    OpenAIRE

    McCord, Jennifer L.; Hayes, Shawn G.; Kaufman, Marc P.

    2008-01-01

    Amiloride, injected into the popliteal artery, has been reported to attenuate the reflex pressor response to static contraction of the triceps surae muscles. Both mechanical and metabolic stimuli arising in contracting skeletal muscle are believed to evoke this effect, which has been named the exercise pressor reflex. Amiloride blocks both acid-sensing ion channels, as well as epithelial sodium channels. Nevertheless, amiloride is thought to block the metabolic stimulus to the reflex, because...

  13. Sensing with Ion Channels

    CERN Document Server

    Martinac, Boris

    2008-01-01

    All living cells are able to detect and translate environmental stimuli into biologically meaningful signals. Sensations of touch, hearing, sight, taste, smell or pain are essential to the survival of all living organisms. The importance of sensory input for the existence of life thus justifies the effort made to understand its molecular origins. Sensing with Ion Channels focuses on ion channels as key molecules enabling biological systems to sense and process the physical and chemical stimuli that act upon cells in their living environment. Its aim is to serve as a reference to ion channel specialists and as a source of new information to non specialists who want to learn about the structural and functional diversity of ion channels and their role in sensory physiology.

  14. ASIC2 Subunits Target Acid-Sensing Ion Channels to the Synapse via an Association with PSD-95

    OpenAIRE

    Zha, Xiang-ming; Costa, Vivian; Harding, Anne Marie S.; Reznikov, Leah; Benson, Christopher J.; Welsh, Michael J.

    2009-01-01

    Acid-sensing ion channel-1a (ASIC1a) mediates H+-gated current to influence normal brain physiology and impact several models of disease. Although ASIC2 subunits are widely expressed in brain and modulate ASIC1a current, their function remains poorly understood. We identified ASIC2a in dendrites, dendritic spines, and brain synaptosomes. This localization largely relied on ASIC2a binding to PSD-95 and matched that of ASIC1a, which does not co-immunoprecipitate with PSD-95. We found that ASIC2...

  15. Acid-Sensing Ion Channel 2a (ASIC2a) Promotes Surface Trafficking of ASIC2b via Heteromeric Assembly

    OpenAIRE

    Kweon, Hae-Jin; Kim, Dong-Il; Bae, Yeonju; Park, Jae-Yong; Suh, Byung-Chang

    2016-01-01

    Acid-sensing ion channels (ASICs) are proton-activated cation channels that play important roles as typical proton sensors during pathophysiological conditions and normal synaptic activities. Among the ASIC subunits, ASIC2a and ASIC2b are alternative splicing products from the same gene, ACCN1. It has been shown that ASIC2 isoforms have differential subcellular distribution: ASIC2a targets the cell surface by itself, while ASIC2b resides in the ER. However, the underlying mechanism for this d...

  16. Ion sensing method

    Science.gov (United States)

    Smith, Richard Harding; Martin, Glenn Brian

    2004-05-18

    The present invention allows the determination of trace levels of ionic substances in a sample solution (ions, metal ions, and other electrically charged molecules) by coupling a separation method, such as liquid chromatography, with ion selective electrodes (ISE) prepared so as to allow detection at activities below 10.sup.-6 M. The separation method distributes constituent molecules into fractions due to unique chemical and physical properties, such as charge, hydrophobicity, specific binding interactions, or movement in an electrical field. The separated fractions are detected by means of the ISE(s). These ISEs can be used singly or in an array. Accordingly, modifications in the ISEs are used to permit detection of low activities, specifically, below 10.sup.-6 M, by using low activities of the primary analyte (the molecular species which is specifically detected) in the inner filling solution of the ISE. Arrays constructed in various ways allow flow-through sensing for multiple ions.

  17. Anion capture and sensing with cationic boranes: on the synergy of Coulombic effects and onium ion-centred Lewis acidity.

    Science.gov (United States)

    Zhao, Haiyan; Leamer, Lauren A; Gabbaï, François P

    2013-06-21

    Stimulated by the growing importance and recognized toxicity of anions such as fluoride, cyanide and azides, we have, in the past few years, developed a family of Lewis acidic triarylboranes that can be used for the complexation of these anions in organic and protic solvents, including water. A central aspect of our approach lies in the decoration of the boranes with peripheral ammonium, phosphonium, sulfonium stibonium or telluronium groups. The presence of these cationic groups provides a Coulombic drive for the capture of the anion, leading to boranes that can be used in aqueous solutions where anion hydration and/or protonation are usually competitive. The anion affinity of these boranes can be markedly enhanced by narrowing the separation between the anion binding site (i.e. the boron atom) and the onium ion. In such systems, the latent Lewis acidity of the onium ion also plays a role as manifested by the formation of B-X→E (E = P, S, Sb, or Te; X = F, CN or N3) chelate motifs that provide additional stability to the resulting complexes. These effects, which are maximum in stibonium and telluronium boranes, show that the Lewis acidity of heavy onium ions can be exploited for anion coordination and capture. The significance of these advances is illustrated by the development of applications in anion sensing, fluorination chemistry and (18)F radiolabeling for positron emission tomography.

  18. Evidence for role of acid-sensing ion channels in nucleus ambiguus neurons: essential differences in anesthetized versus awake rats.

    Science.gov (United States)

    Brailoiu, G Cristina; Deliu, Elena; Altmann, Joseph B; Chitravanshi, Vineet; Brailoiu, Eugen

    2014-08-01

    Acid-sensing ion channels (ASIC) are widely expressed in several brain regions including medulla; their role in physiology and pathophysiology is incompletely understood. We examined the effect of acidic pH of 6.2 on the medullary neurons involved in parasympathetic cardiac control. Our results indicate that retrogradely labeled cardiac vagal neurons of nucleus ambiguus are depolarized by acidic pH. In addition, acidic saline of pH 6.2 increases cytosolic Ca(2+) concentration by promoting Ca(2+) influx in nucleus ambiguus neurons. In vivo studies indicate that microinjection of acidic artificial cerebrospinal fluid (pH 6.2) into the nucleus ambiguus decreases the heart rate in conscious rats, whereas it has no effect in anesthetized animals. Pretreatment with either amiloride or benzamil, two widely used ASIC blockers, abolishes both the in vitro and in vivo effects elicited by pH 6.2. Our findings support a critical role for ASIC in modulation of cardiac vagal tone and provide a potential mechanism for acidosis-induced bradycardia, while identifying important differences in the response to acidic pH between anesthetized and conscious rats.

  19. Endomorphins potentiate acid-sensing ion channel currents and enhance the lactic acid-mediated increase in arterial blood pressure: effects amplified in hindlimb ischaemia.

    Science.gov (United States)

    Farrag, Mohamed; Drobish, Julie K; Puhl, Henry L; Kim, Joyce S; Herold, Paul B; Kaufman, Marc P; Ruiz-Velasco, Victor

    2017-12-01

    Chronic limb ischaemia, characterized by inflammatory mediator release and a low extracellular pH, leads to acid-sensing ion channel (ASIC) activation and reflexively increases mean arterial pressure; endomorphin release is also increased under inflammatory conditions. We examined the modulation of ASIC currents by endomorphins in sensory neurons from rats with freely perfused and ligated femoral arteries: peripheral artery disease (PAD) model. Endomorphins potentiated sustained ASIC currents in both groups of dorsal root ganglion neurons, independent of mu opioid receptor stimulation or G protein activation. Intra-arterial administration of lactic acid (to simulate exercising muscle and evoke a pressor reflex), endomorphin-2 and naloxone resulted in a significantly greater pressor response than lactic acid alone, while administration of APETx2 inhibited endomorphin's enhancing effect in both groups. These results suggest a novel role for endomorphins in modulating ASIC function to effect lactic acid-mediated reflex increase in arterial pressure in patients with PAD. Chronic muscle ischaemia leads to accumulation of lactic acid and other inflammatory mediators with a subsequent drop in interstitial pH. Acid-sensing ion channels (ASICs), expressed in thin muscle afferents, sense the decrease in pH and evoke a pressor reflex known to increase mean arterial pressure. The naturally occurring endomorphins are also released by primary afferents under ischaemic conditions. We examined whether high affinity mu opioid receptor (MOR) agonists, endomorphin-1 (E-1) and -2 (E-2), modulate ASIC currents and the lactic acid-mediated pressor reflex. In rat dorsal root ganglion (DRG) neurons, exposure to E-2 in acidic solutions significantly potentiated ASIC currents when compared to acidic solutions alone. The potentiation was significantly greater in DRG neurons isolated from rats whose femoral arteries were ligated for 72 h. Sustained ASIC current potentiation was also observed

  20. Acid-sensing ion channel (ASIC) 1a/2a heteromers have a flexible 2:1/1:2 stoichiometry.

    Science.gov (United States)

    Bartoi, Tudor; Augustinowski, Katrin; Polleichtner, Georg; Gründer, Stefan; Ulbrich, Maximilian H

    2014-06-03

    Acid-sensing ion channels (ASICs) are widely expressed proton-gated Na(+) channels playing a role in tissue acidosis and pain. A trimeric composition of ASICs has been suggested by crystallization. Upon coexpression of ASIC1a and ASIC2a in Xenopus oocytes, we observed the formation of heteromers and their coexistence with homomers by electrophysiology, but could not determine whether heteromeric complexes have a fixed subunit stoichiometry or whether certain stoichiometries are preferred over others. We therefore imaged ASICs labeled with green and red fluorescent proteins on a single-molecule level, counted bleaching steps from GFP and colocalized them with red tandem tetrameric mCherry for many individual complexes. Combinatorial analysis suggests a model of random mixing of ASIC1a and ASIC2a subunits to yield both 2:1 and 1:2 ASIC1a:ASIC2a heteromers together with ASIC1a and ASIC2a homomers.

  1. Acid-sensing ion channels expression, identity and role in the excitability of the cochlear afferent neurons

    Directory of Open Access Journals (Sweden)

    Antonia eGonzález-Garrido

    2015-12-01

    Full Text Available Acid-sensing ion channels (ASICs are activated by an increase in the extracellular proton concentration. There are four genes (ASIC1-4 that encode six subunits, and they are involved in diverse neuronal functions, such as mechanosensation, learning and memory, nociception, and modulation of retinal function. In this study, we characterize the ASIC currents of spiral ganglion neurons (SGNs. These ASIC currents are primarily carried by Na+, exhibit fast activation and desensitization, display a pH50 of 6.2 and are blocked by amiloride, indicating that these are ASIC currents. The ASIC currents were further characterized using several pharmacological tools. Gadolinium and acetylsalicylic acid reduced these currents, and FMRFamide, zinc (at high concentrations and N,N,N’,N’–tetrakis-(2-piridilmetil-etilendiamina (TPEN increased them, indicating that functional ASICs are composed of the subunits ASIC1, ASIC2 and ASIC3. Neomycin and streptomycin reduced the desensitization rate of the ASIC current in SGNs, indicating that ASICs may contribute to the ototoxic action of aminoglycosides. RT-PCR of the spiral ganglion revealed significant expression of all ASIC subunits. By immunohistochemistry the expression of the ASIC1a, ASIC2a, ASIC2b and ASIC3 subunits was detected in SGNs. Although only a few SGNs exhibited action potential firing in response to an acidic stimulus, protons in the extracellular solution modulated SGN activity during sinusoidal stimulation. Our results show that protons modulate the excitability of SGNs via ASICs.

  2. An acid-sensing ion channel from shark (Squalus acanthias) mediates transient and sustained responses to protons.

    Science.gov (United States)

    Springauf, Andreas; Gründer, Stefan

    2010-03-01

    Acid-sensing ion channels (ASICs) are proton-gated Na(+) channels. They are implicated in synaptic transmission, detection of painful acidosis, and possibly sour taste. The typical ASIC current is a transient, completely desensitizing current that can be blocked by the diuretic amiloride. ASICs are present in chordates but are absent in other animals. They have been cloned from urochordates, jawless vertebrates, cartilaginous shark and bony fish, from chicken and different mammals. Strikingly, all ASICs that have so far been characterized from urochordates, jawless vertebrates and shark are not gated by protons, suggesting that proton gating evolved relatively late in bony fish and that primitive ASICs had a different and unknown gating mechanism. Recently, amino acids that are crucial for the proton gating of rat ASIC1a have been identified. These residues are completely conserved in shark ASIC1b (sASIC1b), prompting us to re-evaluate the proton sensitivity of sASIC1b. Here we show that, contrary to previous findings, sASIC1b is indeed gated by protons with half-maximal activation at pH 6.0. sASIC1b desensitizes quickly but incompletely, efficiently encoding transient as well as sustained proton signals. Our results show that the conservation of the amino acids crucial for proton gating can predict proton sensitivity of an ASIC and increase our understanding of the evolution of ASICs.

  3. Inhibition of acid-sensing ion channels by levo-tetrahydropalmatine in rat dorsal root ganglion neurons.

    Science.gov (United States)

    Liu, Ting-Ting; Qu, Zu-Wei; Qiu, Chun-Yu; Qiu, Fang; Ren, Cuixia; Gan, Xiong; Peng, Fang; Hu, Wang-Ping

    2015-02-01

    Levo-tetrahydropalmatine (l-THP), a main bioactive Chinese herbal constituent from the genera Stephania and Corydalis, has been in use in clinical practice for years in China as a traditional analgesic agent. However, the mechanism underlying the analgesic action of l-THP is poorly understood. This study shows that l-THP can exert an inhibitory effect on the functional activity of native acid-sensing ion channels (ASICs), which are believed to mediate pain caused by extracellular acidification. l-THP dose dependently decreased the amplitude of proton-gated currents mediated by ASICs in rat dorsal root ganglion (DRG) neurons. l-THP shifted the proton concentration-response curve downward, with a decrease of 40.93% ± 8.45% in the maximum current response to protons, with no significant change in the pH0.5 value. Moreover, l-THP can alter the membrane excitability of rat DRG neurons to acid stimuli. It significantly decreased the number of action potentials and the amplitude of the depolarization induced by an extracellular pH drop. Finally, peripherally administered l-THP inhibited the nociceptive response to intraplantar injection of acetic acid in rats. These results indicate that l-THP can inhibit the functional activity of ASICs in dissociated primary sensory neurons and relieve acidosis-evoked pain in vivo, which for the first time provides a novel peripheral mechanism underlying the analgesic action of l-THP. © 2014 Wiley Periodicals, Inc.

  4. Blockade of acid sensing ion channels attenuates the augmented exercise pressor reflex in rats with chronic femoral artery occlusion.

    Science.gov (United States)

    Tsuchimochi, Hirotsugu; Yamauchi, Katsuya; McCord, Jennifer L; Kaufman, Marc P

    2011-12-15

    We found previously that static contraction of the hindlimb muscles of rats whose femoral artery was ligated evoked a larger reflex pressor response (i.e. exercise pressor reflex) than did static contraction of the contralateral hindlimb muscles which were freely perfused. Ligating a femoral artery in rats results in blood flow patterns to the muscles that are remarkably similar to those displayed by humans with peripheral artery disease. Using decerebrated rats, we tested the hypothesis that the augmented exercise pressor reflex in rats with a ligated femoral artery is attenuated by blockade of the acid sensing ion channel (ASIC) 3. We found that femoral arterial injection of either amiloride (5 and 50 μg kg(-1)) or APETx2 (100 μg kg(-1)) markedly attenuated the reflex in rats with a ligated femoral artery. In contrast, these ASIC antagonists had only modest effects on the reflex in rats with freely perfused hindlimbs. Tests of specificity of the two antagonists revealed that the low dose of amiloride and APETx2 greatly attenuated the pressor response to lactic acid, an ASIC agonist, but did not attenuate the pressor response to capsaicin, a TRPV1 agonist. In contrast, the high dose of amiloride attenuated the pressor responses to lactic acid, but also attenuated the pressor response to capsaicin. We conclude that ASIC3 on thin fibre muscle afferents plays an important role in evoking the exercise pressor reflex in rats with a compromised arterial blood supply to the working muscles.

  5. Acid-Sensing Ion Channels Expression, Identity and Role in the Excitability of the Cochlear Afferent Neurons

    Science.gov (United States)

    González-Garrido, Antonia; Vega, Rosario; Mercado, Francisco; López, Iván A.; Soto, Enrique

    2015-01-01

    Acid-sensing ion channels (ASICs) are activated by an increase in the extracellular proton concentration. There are four genes (ASIC1-4) that encode six subunits, and they are involved in diverse neuronal functions, such as mechanosensation, learning and memory, nociception, and modulation of retinal function. In this study, we characterize the ASIC currents of spiral ganglion neurons (SGNs). These ASIC currents are primarily carried by Na+, exhibit fast activation and desensitization, display a pH50 of 6.2 and are blocked by amiloride, indicating that these are ASIC currents. The ASIC currents were further characterized using several pharmacological tools. Gadolinium and acetylsalicylic acid reduced these currents, and FMRFamide, zinc (at high concentrations) and N,N,N’,N’–tetrakis-(2-piridilmetil)-ethylenediamine increased them, indicating that functional ASICs are composed of the subunits ASIC1, ASIC2, and ASIC3. Neomycin and streptomycin reduced the desensitization rate of the ASIC current in SGNs, indicating that ASICs may contribute to the ototoxic action of aminoglycosides. RT-PCR of the spiral ganglion revealed significant expression of all ASIC subunits. By immunohistochemistry the expression of the ASIC1a, ASIC2a, ASIC2b, and ASIC3 subunits was detected in SGNs. Although only a few SGNs exhibited action potential firing in response to an acidic stimulus, protons in the extracellular solution modulated SGN activity during sinusoidal stimulation. Our results show that protons modulate the excitability of SGNs via ASICs. PMID:26733809

  6. Characterisation of a human acid-sensing ion channel (hASIC1a) endogenously expressed in HEK293 cells.

    Science.gov (United States)

    Gunthorpe, M J; Smith, G D; Davis, J B; Randall, A D

    2001-08-01

    Acid-sensing ion channels (ASICs) are a new and expanding family of proton-gated cation (Na+/Ca2+) channels that are widely expressed in sensory neurons and the central nervous system. Their distribution suggests that they may play a critical role in the sensation of the pain that accompanies tissue acidosis and may also be important in detecting the subtle pH variations that occur during neuronal signalling. Here, using whole-cell patch-clamp electrophysiology and reverse transcriptase-polymerase chain reaction (RT-PCR), we show that HEK293 cells, a commonly used cell line for the expression and characterisation of many ion channels, functionally express an endogenous proton-gated conductance attributable to the activity of human ASIC1a. These data therefore represent the first functional characterisation of hASIC1 and have many important implications for the use of HEK293 cells as a host cell system for the study of ASICs, vanilloid receptor-1 and any other proton-gated channel. With this latter point in mind we have devised a simple desensitisation strategy to selectively remove the contribution of hASIC1a from proton-gated currents recorded from HEK293 cells expressing vanilloid receptor-1.

  7. Activation of acid-sensing ion channels by localized proton transient reveals their role in proton signaling.

    Science.gov (United States)

    Zeng, Wei-Zheng; Liu, Di-Shi; Liu, Lu; She, Liang; Wu, Long-Jun; Xu, Tian-Le

    2015-09-15

    Extracellular transients of pH alterations likely mediate signal transduction in the nervous system. Neuronal acid-sensing ion channels (ASICs) act as sensors for extracellular protons, but the mechanism underlying ASIC activation remains largely unknown. Here, we show that, following activation of a light-activated proton pump, Archaerhodopsin-3 (Arch), proton transients induced ASIC currents in both neurons and HEK293T cells co-expressing ASIC1a channels. Using chimera proteins that bridge Arch and ASIC1a by a glycine/serine linker, we found that successful coupling occurred within 15 nm distance. Furthermore, two-cell sniffer patch recording revealed that regulated release of protons through either Arch or voltage-gated proton channel Hv1 activated neighbouring cells expressing ASIC1a channels. Finally, computational modelling predicted the peak proton concentration at the intercellular interface to be at pH 6.7, which is acidic enough to activate ASICs in vivo. Our results highlight the pathophysiological role of proton signalling in the nervous system.

  8. In silico assessment of interaction of sea anemone toxin APETx2 and acid sensing ion channel 3

    International Nuclear Information System (INIS)

    Rahman, Taufiq; Smith, Ewan St. John

    2014-01-01

    Highlights: • We have made a reasonable model of rat ASIC3 using published structure of chicken ASIC1. • We have docked sea anemone toxin APETx2 on the model. • We have identified two putative sites for toxin binding. • We have argued for plausibility one site over the other. • We have identified the residues that are likely to be critical for APETx2–ASIC3 interaction. - Abstract: Acid sensing ion channels (ASICs) are proton-gated cation channels that are expressed throughout the nervous system and have been implicated in mediating sensory perception of noxious stimuli. Amongst the six ASIC isoforms, ASIC1a, 1b, 2a and 3 form proton-gated homomers, which differ in their activation and inactivation kinetics, expression profiles and pharmacological modulation; protons do not gate ASIC2b and ASIC4. As with many other ion channels, structure-function studies of ASICs have been greatly aided by the discovery of some toxins that act in isoform-specific ways. ASIC3 is predominantly expressed by sensory neurons of the peripheral nervous system where it acts to detect acid as a noxious stimulus and thus plays an important role in nociception. ASIC3 is the only ASIC subunit that is inhibited by the sea anemone (Anthopleura elegantissima)-derived toxin APETx2. However, the molecular mechanism by which APETx2 interacts with ASIC3 remains largely unknown. In this study, we made a homology model of ASIC3 and used extensive protein–protein docking to predict for the first time, the probable sites of APETx2 interaction on ASIC3. Additionally, using computational alanine scanning, we also suggest the ‘hot-spots’ that are likely to be critical for ASIC3–APETx2 interaction

  9. In silico assessment of interaction of sea anemone toxin APETx2 and acid sensing ion channel 3

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Taufiq, E-mail: mtur2@cam.ac.uk; Smith, Ewan St. John

    2014-07-18

    Highlights: • We have made a reasonable model of rat ASIC3 using published structure of chicken ASIC1. • We have docked sea anemone toxin APETx2 on the model. • We have identified two putative sites for toxin binding. • We have argued for plausibility one site over the other. • We have identified the residues that are likely to be critical for APETx2–ASIC3 interaction. - Abstract: Acid sensing ion channels (ASICs) are proton-gated cation channels that are expressed throughout the nervous system and have been implicated in mediating sensory perception of noxious stimuli. Amongst the six ASIC isoforms, ASIC1a, 1b, 2a and 3 form proton-gated homomers, which differ in their activation and inactivation kinetics, expression profiles and pharmacological modulation; protons do not gate ASIC2b and ASIC4. As with many other ion channels, structure-function studies of ASICs have been greatly aided by the discovery of some toxins that act in isoform-specific ways. ASIC3 is predominantly expressed by sensory neurons of the peripheral nervous system where it acts to detect acid as a noxious stimulus and thus plays an important role in nociception. ASIC3 is the only ASIC subunit that is inhibited by the sea anemone (Anthopleura elegantissima)-derived toxin APETx2. However, the molecular mechanism by which APETx2 interacts with ASIC3 remains largely unknown. In this study, we made a homology model of ASIC3 and used extensive protein–protein docking to predict for the first time, the probable sites of APETx2 interaction on ASIC3. Additionally, using computational alanine scanning, we also suggest the ‘hot-spots’ that are likely to be critical for ASIC3–APETx2 interaction.

  10. Expression of acid-sensing ion channels and selection of reference genes in mouse and naked mole rat.

    Science.gov (United States)

    Schuhmacher, Laura-Nadine; Smith, Ewan St John

    2016-12-13

    Acid-sensing ion channels (ASICs) are a family of ion channels comprised of six subunits encoded by four genes and they are expressed throughout the peripheral and central nervous systems. ASICs have been implicated in a wide range of physiological and pathophysiological processes: pain, breathing, synaptic plasticity and excitotoxicity. Unlike mice and humans, naked mole-rats do not perceive acid as a noxious stimulus, even though their sensory neurons express functional ASICs, likely an adaptation to living in a hypercapnic subterranean environment. Previous studies of ASIC expression in the mammalian nervous system have often not examined all subunits, or have failed to adequately quantify expression between tissues; to date there has been no attempt to determine ASIC expression in the central nervous system of the naked mole-rat. Here we perform a geNorm study to identify reliable housekeeping genes in both mouse and naked mole-rat and then use quantitative real-time PCR to estimate the relative amounts of ASIC transcripts in different tissues of both species. We identify RPL13A (ribosomal protein L13A) and CANX (calnexin), and β-ACTIN and EIF4A (eukaryotic initiation factor 4a) as being the most stably expressed housekeeping genes in mouse and naked mole-rat, respectively. In both species, ASIC3 was most highly expressed in dorsal root ganglia (DRG), and ASIC1a, ASIC2b and ASIC3 were more highly expressed across all brain regions compared to the other subunits. We also show that ASIC4, a proton-insensitive subunit of relatively unknown function, was highly expressed in all mouse tissues apart from DRG and hippocampus, but was by contrast the lowliest expressed ASIC in all naked mole-rat tissues.

  11. Acid-sensing ion channels (ASICs) in mouse skeletal muscle afferents are heteromers composed of ASIC1a, ASIC2, and ASIC3 subunits

    OpenAIRE

    Gautam, Mamta; Benson, Christopher J.

    2013-01-01

    Acid-sensing ion channels (ASICs) are expressed in skeletal muscle afferents, in which they sense extracellular acidosis and other metabolites released during ischemia and exercise. ASICs are formed as homotrimers or heterotrimers of several isoforms (ASIC1a, ASIC1b, ASIC2a, ASIC2b, and ASIC3), with each channel displaying distinct properties. To dissect the ASIC composition in muscle afferents, we used whole-cell patch-clamp recordings to study the properties of acid-evoked currents (amplitu...

  12. Subtype-specific Modulation of Acid-sensing Ion Channel (ASIC) Function by 2-Guanidine-4-methylquinazoline*

    Science.gov (United States)

    Alijevic, Omar; Kellenberger, Stephan

    2012-01-01

    Acid-sensing ion channels (ASICs) are neuronal Na+-selective channels that are transiently activated by extracellular acidification. ASICs are involved in fear and anxiety, learning, neurodegeneration after ischemic stroke, and pain sensation. The small molecule 2-guanidine-4-methylquinazoline (GMQ) was recently shown to open ASIC3 at physiological pH. We have investigated the mechanisms underlying this effect and the possibility that GMQ may alter the function of other ASICs besides ASIC3. GMQ shifts the pH dependence of activation to more acidic pH in ASIC1a and ASIC1b, whereas in ASIC3 this shift goes in the opposite direction and is accompanied by a decrease in its steepness. GMQ also induces an acidic shift of the pH dependence of inactivation of ASIC1a, -1b, -2a, and -3. As a consequence, the activation and inactivation curves of ASIC3 but not other ASICs overlap in the presence of GMQ at pH 7.4, thereby creating a window current. At concentrations >1 mm, GMQ decreases maximal peak currents by reducing the unitary current amplitude. Mutation of residue Glu-79 in the palm domain of ASIC3, previously shown to be critical for channel opening by GMQ, disrupted the GMQ effects on inactivation but not activation. This suggests that this residue is involved in the consequences of GMQ binding rather than in the binding interaction itself. This study describes the mechanisms underlying the effects of a novel class of ligands that modulate the function of all ASICs as well as activate ASIC3 at physiological pH. PMID:22948146

  13. Subtype-specific modulation of acid-sensing ion channel (ASIC) function by 2-guanidine-4-methylquinazoline.

    Science.gov (United States)

    Alijevic, Omar; Kellenberger, Stephan

    2012-10-19

    Acid-sensing ion channels (ASICs) are neuronal Na(+)-selective channels that are transiently activated by extracellular acidification. ASICs are involved in fear and anxiety, learning, neurodegeneration after ischemic stroke, and pain sensation. The small molecule 2-guanidine-4-methylquinazoline (GMQ) was recently shown to open ASIC3 at physiological pH. We have investigated the mechanisms underlying this effect and the possibility that GMQ may alter the function of other ASICs besides ASIC3. GMQ shifts the pH dependence of activation to more acidic pH in ASIC1a and ASIC1b, whereas in ASIC3 this shift goes in the opposite direction and is accompanied by a decrease in its steepness. GMQ also induces an acidic shift of the pH dependence of inactivation of ASIC1a, -1b, -2a, and -3. As a consequence, the activation and inactivation curves of ASIC3 but not other ASICs overlap in the presence of GMQ at pH 7.4, thereby creating a window current. At concentrations >1 mM, GMQ decreases maximal peak currents by reducing the unitary current amplitude. Mutation of residue Glu-79 in the palm domain of ASIC3, previously shown to be critical for channel opening by GMQ, disrupted the GMQ effects on inactivation but not activation. This suggests that this residue is involved in the consequences of GMQ binding rather than in the binding interaction itself. This study describes the mechanisms underlying the effects of a novel class of ligands that modulate the function of all ASICs as well as activate ASIC3 at physiological pH.

  14. Acid-Sensing Ion Channel 1a Regulates Fate of Rat Nucleus Pulposus Cells in Acid Stimulus Through Endoplasmic Reticulum Stress

    Directory of Open Access Journals (Sweden)

    Xie Zhi-Yang

    2018-02-01

    Full Text Available Acid-sensing ion channel 1a (ASIC1a participates in human intervertebral disc degeneration (IVDD and regulates the destiny of nucleus pulposus cells (NPCs in acid stimulus. However, the mechanism of ASIC1a activation and its downstream pathway remain unclear. Endoplasmic reticulum (ER stress also participates in the acid-induced apoptosis of NPCs. The main purpose of this study was to investigate whether there is any connection between ASIC1a and ER stress in an acid-induced nucleus pulposus degeneration model. The IVDs of Sprague-Dawley rats were stained by immunohistochemical staining to evaluate the expression of ASIC1a in normal and degenerated rat nucleus pulposus. ASIC1a expression was also quantified by quantitative real-time-polymerase chain reaction and Western blotting analysis. NPCs were exposed to the culture media with acidity at pH 7.2 and 6.5 for 24 h, with or without 4-phenylbutyrate (4-PBA, a blocker of the ER stress pathway. Cell apoptosis was examined by Annexin V/Propidium Iodide (PI staining and was quantified using flow cytometry analysis. ASIC1a-mediated intracellular calcium was determined by Ca2+ imaging using Fura-2-AM. Acidity-induced changes in ER stress markers were studied using Western blotting analysis. In vivo, ASIC1a expression was upregulated in natural degeneration. In vitro, acid stimulus increased intracellular calcium levels, but this effect was blocked by knockdown of ASIC1a, and this reversal was partly inhibited by 4-PBA. In addition, blockade of ASIC1a reduced expression of ER stress markers, especially the proapoptotic markers. ASIC1a partly regulates ER stress and promotes apoptosis of NPCs under acid stimulus and may be a novel therapeutic target in IVDD.

  15. Acid-Sensing Ion Channel 1a Regulates Fate of Rat Nucleus Pulposus Cells in Acid Stimulus Through Endoplasmic Reticulum Stress.

    Science.gov (United States)

    Xie, Zhi-Yang; Chen, Lu; Zhang, Cong; Liu, Lei; Wang, Feng; Cai, Feng; Wang, Xiao-Hu; Shi, Rui; Sinkemani, Arjun; Yu, Hao-Min; Hong, Xin; Wu, Xiao-Tao

    2018-01-01

    Acid-sensing ion channel 1a (ASIC1a) participates in human intervertebral disc degeneration (IVDD) and regulates the destiny of nucleus pulposus cells (NPCs) in acid stimulus. However, the mechanism of ASIC1a activation and its downstream pathway remain unclear. Endoplasmic reticulum (ER) stress also participates in the acid-induced apoptosis of NPCs. The main purpose of this study was to investigate whether there is any connection between ASIC1a and ER stress in an acid-induced nucleus pulposus degeneration model. The IVDs of Sprague-Dawley rats were stained by immunohistochemical staining to evaluate the expression of ASIC1a in normal and degenerated rat nucleus pulposus. ASIC1a expression was also quantified by quantitative real-time-polymerase chain reaction and Western blotting analysis. NPCs were exposed to the culture media with acidity at pH 7.2 and 6.5 for 24 h, with or without 4-phenylbutyrate (4-PBA, a blocker of the ER stress pathway). Cell apoptosis was examined by Annexin V/Propidium Iodide (PI) staining and was quantified using flow cytometry analysis. ASIC1a-mediated intracellular calcium was determined by Ca 2+ imaging using Fura-2-AM. Acidity-induced changes in ER stress markers were studied using Western blotting analysis. In vivo , ASIC1a expression was upregulated in natural degeneration. In vitro , acid stimulus increased intracellular calcium levels, but this effect was blocked by knockdown of ASIC1a, and this reversal was partly inhibited by 4-PBA. In addition, blockade of ASIC1a reduced expression of ER stress markers, especially the proapoptotic markers. ASIC1a partly regulates ER stress and promotes apoptosis of NPCs under acid stimulus and may be a novel therapeutic target in IVDD.

  16. Acid-sensing ion channel (ASIC) structure and function: Insights from spider, snake and sea anemone venoms.

    Science.gov (United States)

    Cristofori-Armstrong, Ben; Rash, Lachlan D

    2017-12-01

    Acid-sensing ion channels (ASICs) are proton-activated cation channels that are expressed in a variety of neuronal and non-neuronal tissues. As proton-gated channels, they have been implicated in many pathophysiological conditions where pH is perturbed. Venom derived compounds represent the most potent and selective modulators of ASICs described to date, and thus have been invaluable as pharmacological tools to study ASIC structure, function, and biological roles. There are now ten ASIC modulators described from animal venoms, with those from snakes and spiders favouring ASIC1, while the sea anemones preferentially target ASIC3. Some modulators, such as the prototypical ASIC1 modulator PcTx1 have been studied in great detail, while some of the newer members of the club remain largely unstudied. Here we review the current state of knowledge on venom derived ASIC modulators, with a particular focus on their molecular interaction with ASICs, what they have taught us about channel structure, and what they might still reveal about ASIC function and pathophysiological roles. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.' Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Acid-sensing ion channel (ASIC) 4 predominantly localizes to an early endosome-related organelle upon heterologous expression.

    Science.gov (United States)

    Schwartz, Verena; Friedrich, Katharina; Polleichtner, Georg; Gründer, Stefan

    2015-12-15

    Acid-sensing ion channels (ASICs) are voltage-independent proton-gated amiloride sensitive sodium channels, belonging to the DEG/ENaC gene family. Six different ASICs have been identified (ASIC1a, ASIC1b, ASIC2a, ASIC2b, ASIC3, ASIC4) that are activated by a drop in extracellular pH, either as homo- or heteromers. An exception is ASIC4, which is not activated by protons as a homomer and which does not contribute to functional heteromeric ASICs. Insensitivity of ASIC4 to protons and its comparatively low sequence identity to other ASICs (45%) raises the question whether ASIC4 may have different functions than other ASICs. In this study, we therefore investigated the subcellular localization of ASIC4 in heterologous cell lines, which revealed a surprising accumulation of the channel in early endosome-related vacuoles. Moreover, we identified an unique amino-terminal motif as important for forward-trafficking from the ER/Golgi to the early endosome-related compartment. Collectively, our results show that heterologously expressed ASIC4 predominantly resides in an intracellular endosomal compartment.

  18. Effect of acid-sensing ion channel 1a on the process of liver fibrosis under hyperglycemia

    International Nuclear Information System (INIS)

    Wang, Huan; Wang, Ying-hong; Yang, Feng; Li, Xiao-feng; Tian, Yuan-yao; Ni, Ming-ming; Zuo, Long-quan; Meng, Xiao-Ming; Huang, Yan

    2015-01-01

    Metabolic syndrome characterized by hyperglycemia contributes to nonalcoholic steatohepatitis-associated liver fibrosis. This study was to investigate the effects of Acid-sensing ion Channel 1a (ASIC1a) on the process of liver fibrosis under hyperglycemia. Results showed that high glucose significantly worsen the pathology of liver fibrosis in vivo. In vitro, high glucose stimulated proliferation, activation and extracellular matrix (ECM) production in HSCs, and enhanced the effect of PDGF-BB on the activation and proliferation of HSCs. These effects could be attenuated by ASIC1a specific inhibitor Psalmotoxin-1(PcTx1) or specific ShRNA for ASIC1a through Notch1/Hes-1 pathways. These data indicate that ASIC1a plays an important role in diabetes complication liver fibrosis. - Highlights: • Hyperglycemia is a risk factor for the process of liver fibrosis. • ASIC1a may be a key factor linking between high glucose and liver fibrosis. • Notch1/Hes-1 may involve to the process of liver fibrosis under hyperglycemia.

  19. Effect of acid-sensing ion channel 1a on the process of liver fibrosis under hyperglycemia

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huan, E-mail: wanghuan7@126.com [School of Pharmacy, Anhui Medical University, Hefei, 230032 (China); Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032 (China); Wang, Ying-hong; Yang, Feng; Li, Xiao-feng; Tian, Yuan-yao; Ni, Ming-ming; Zuo, Long-quan; Meng, Xiao-Ming [School of Pharmacy, Anhui Medical University, Hefei, 230032 (China); Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032 (China); Huang, Yan, E-mail: aydhy@126.com [School of Pharmacy, Anhui Medical University, Hefei, 230032 (China); Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032 (China)

    2015-12-25

    Metabolic syndrome characterized by hyperglycemia contributes to nonalcoholic steatohepatitis-associated liver fibrosis. This study was to investigate the effects of Acid-sensing ion Channel 1a (ASIC1a) on the process of liver fibrosis under hyperglycemia. Results showed that high glucose significantly worsen the pathology of liver fibrosis in vivo. In vitro, high glucose stimulated proliferation, activation and extracellular matrix (ECM) production in HSCs, and enhanced the effect of PDGF-BB on the activation and proliferation of HSCs. These effects could be attenuated by ASIC1a specific inhibitor Psalmotoxin-1(PcTx1) or specific ShRNA for ASIC1a through Notch1/Hes-1 pathways. These data indicate that ASIC1a plays an important role in diabetes complication liver fibrosis. - Highlights: • Hyperglycemia is a risk factor for the process of liver fibrosis. • ASIC1a may be a key factor linking between high glucose and liver fibrosis. • Notch1/Hes-1 may involve to the process of liver fibrosis under hyperglycemia.

  20. The Human Acid-Sensing Ion Channel ASIC1a: Evidence for a Homotetrameric Assembly State at the Cell Surface.

    Directory of Open Access Journals (Sweden)

    Miguel Xavier van Bemmelen

    Full Text Available The chicken acid-sensing ion channel ASIC1 has been crystallized as a homotrimer. We address here the oligomeric state of the functional ASIC1 in situ at the cell surface. The oligomeric states of functional ASIC1a and mutants with additional cysteines introduced in the extracellular pore vestibule were resolved on SDS-PAGE. The functional ASIC1 complexes were stabilized at the cell surface of Xenopus laevis oocytes or CHO cells either using the sulfhydryl crosslinker BMOE, or sodium tetrathionate (NaTT. Under these different crosslinking conditions ASIC1a migrates as four distinct oligomeric states that correspond by mass to multiples of a single ASIC1a subunit. The relative importance of each of the four ASIC1a oligomers was critically dependent on the availability of cysteines in the transmembrane domain for crosslinking, consistent with the presence of ASIC1a homo-oligomers. The expression of ASIC1a monomers, trimeric or tetrameric concatemeric cDNA constructs resulted in functional channels. The resulting ASIC1a complexes are resolved as a predominant tetramer over the other oligomeric forms, after stabilization with BMOE or NaTT and SDS-PAGE/western blot analysis. Our data identify a major ASIC1a homotetramer at the surface membrane of the cell expressing functional ASIC1a channel.

  1. Modulation of Acid-sensing Ion Channel 1a by Intracellular pH and Its Role in Ischemic Stroke.

    Science.gov (United States)

    Li, Ming-Hua; Leng, Tian-Dong; Feng, Xue-Chao; Yang, Tao; Simon, Roger P; Xiong, Zhi-Gang

    2016-08-26

    An important contributor to brain ischemia is known to be extracellular acidosis, which activates acid-sensing ion channels (ASICs), a family of proton-gated sodium channels. Lines of evidence suggest that targeting ASICs may lead to novel therapeutic strategies for stroke. Investigations of the role of ASICs in ischemic brain injury have naturally focused on the role of extracellular pH in ASIC activation. By contrast, intracellular pH (pHi) has received little attention. This is a significant gap in our understanding because the ASIC response to extracellular pH is modulated by pHi, and activation of ASICs by extracellular protons is paradoxically enhanced by intracellular alkalosis. Our previous studies show that acidosis-induced cell injury in in vitro models is attenuated by intracellular acidification. However, whether pHi affects ischemic brain injury in vivo is completely unknown. Furthermore, whereas ASICs in native neurons are composed of different subunits characterized by distinct electrophysiological/pharmacological properties, the subunit-dependent modulation of ASIC activity by pHi has not been investigated. Using a combination of in vitro and in vivo ischemic brain injury models, electrophysiological, biochemical, and molecular biological approaches, we show that the intracellular alkalizing agent quinine potentiates, whereas the intracellular acidifying agent propionate inhibits, oxygen-glucose deprivation-induced cell injury in vitro and brain ischemia-induced infarct volume in vivo Moreover, we find that the potentiation of ASICs by quinine depends on the presence of the ASIC1a, ASIC2a subunits, but not ASIC1b, ASIC3 subunits. Furthermore, we have determined the amino acids in ASIC1a that are involved in the modulation of ASICs by pHi. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Acid-sensing ion channels in trigeminal ganglion neurons innervating the orofacial region contribute to orofacial inflammatory pain.

    Science.gov (United States)

    Fu, Hui; Fang, Peng; Zhou, Hai-Yun; Zhou, Jun; Yu, Xiao-Wei; Ni, Ming; Zheng, Jie-Yan; Jin, You; Chen, Jian-Guo; Wang, Fang; Hu, Zhuang-Li

    2016-02-01

    Orofacial pain is a common clinical symptom that is accompanied by tooth pain, migraine and gingivitis. Accumulating evidence suggests that acid-sensing ion channels (ASICs), especially ASIC3, can profoundly affect the physiological properties of nociception in peripheral sensory neurons. The aim of this study is to examine the contribution of ASICs in trigeminal ganglion (TG) neurons to orofacial inflammatory pain. A Western blot (WB), immunofluorescence assay of labelled trigeminal ganglion neurons, orofacial formalin test, cell preparation and electrophysiological experiments are performed. This study demonstrated that ASIC1, ASIC2a and ASIC3 are highly expressed in TG neurons innervating the orofacial region of rats. The amplitude of ASIC currents in these neurons increased 119.72% (for ASIC1-like current) and 230.59% (for ASIC3-like current) in the formalin-induced orofacial inflammatory pain model. In addition, WB and immunofluorescence assay demonstrated a significantly augmented expression of ASICs in orofacial TG neurons during orofacial inflammation compared with the control group. The relative protein density of ASIC1, ASIC2a and ASIC3 also increased 58.82 ± 8.92%, 45.30 ± 11.42% and 55.32 ± 14.71%, respectively, compared with the control group. Furthermore, pharmacological blockade of ASICs and genetic deletion of ASIC1 attenuated the inflammation response. These findings indicate that peripheral inflammation can induce the upregulation of ASICs in TG neurons, causing orofacial inflammatory pain. Additionally, the specific inhibitor of ASICs may have a significant analgesic effect on orofacial inflammatory pain. © 2016 John Wiley & Sons Australia, Ltd.

  3. Acid-sensing ion channels contribute to chemosensitivity of breathing-related neurons of the nucleus of the solitary tract.

    Science.gov (United States)

    Huda, Rafiq; Pollema-Mays, Sarah L; Chang, Zheng; Alheid, George F; McCrimmon, Donald R; Martina, Marco

    2012-10-01

    Cellular mechanisms of central pH chemosensitivity remain largely unknown. The nucleus of the solitary tract (NTS) integrates peripheral afferents with central pathways controlling breathing; NTS neurons function as central chemosensors, but only limited information exists concerning the ionic mechanisms involved. Acid-sensing ion channels (ASICs) mediate chemosensitivity in nociceptive terminals, where pH values ∼6.5 are not uncommon in inflammation, but are also abundantly expressed throughout the brain where pHi s tightly regulated and their role is less clear. Here we test the hypothesis that ASICs are expressed in NTS neurons and contribute to intrinsic chemosensitivity and control of breathing. In electrophysiological recordings from acute rat NTS slices, ∼40% of NTS neurons responded to physiological acidification (pH 7.0) with a transient depolarization. This response was also present in dissociated neurons suggesting an intrinsic mechanism. In voltage clamp recordings in slices, a pH drop from 7.4 to 7.0 induced ASIC-like inward currents (blocked by 100 μM amiloride) in ∼40% of NTS neurons, while at pH ≤ 6.5 these currents were detected in all neurons tested; RT-PCR revealed expression of ASIC1 and, less abundantly, ASIC2 in the NTS. Anatomical analysis of dye-filled neurons showed that ASIC-dependent chemosensitive cells (cells responding to pH 7.0) cluster dorsally in the NTS. Using in vivo retrograde labelling from the ventral respiratory column, 90% (9/10) of the labelled neurons showed an ASIC-like response to pH 7.0, suggesting that ASIC currents contribute to control of breathing. Accordingly, amiloride injection into the NTS reduced phrenic nerve activity of anaesthetized rats with an elevated arterial P(CO(2)) .

  4. Neuroprotective Effects of Psalmotoxin-1, an Acid-Sensing Ion Channel (ASIC) Inhibitor, in Ischemia Reperfusion in Mouse Eyes.

    Science.gov (United States)

    Dibas, Adnan; Millar, Cameron; Al-Farra, Abraham; Yorio, Thomas

    2018-03-29

    The purpose of the current study is to assess changes in the expression of Acid-Sensing Ion Channel (ASIC)1a and ASIC2 in retinal ganglion cells (RGCs) after retinal ischemia and reperfusion (I/R) injury and to test if inhibition of ASIC1a provides RGC neuroprotection. Transient ischemia was induced in one eye of C57BL/6 mice by raising intraocular pressure to 120 mmHg for 60 min followed by retinal reperfusion by restoring normal pressure. RGC function was measured by Pattern electroretinography (PERG). In addition, retinal ASIC1a and ASIC2 were observed by immunohistochemistry and western blot. Changes in calpain, fodrin, heat shock protein 70 (HSP70), Brn3a, super oxide dismutase-1 (SOD1), catalase, and glutathione perioxidase-4 (GPX4) protein levels were assessed by western blot. RGC numbers were measured by immunohistochemistry on whole retinal flat mounts using anti-RNA binding protein with multiple splicing (RBPMS) antibodies. Intravitreal injection of psalmotoxin-1, a selective ASIC1a blocker, was used to assess the neuroprotective effect of ASIC1a inhibition. Levels of ASIC1a and ASIC2 after I/R increased in RGCs. Upregulation of ASIC1a but not ASIC2 was attenuated by intravitreal injection of psalmotoxin-1. I/R induced activation of calpain and degradation of fodrin, HSP70, and reduction in Brn3a. In contrast, while psalmotoxin-1 attenuated calpain activation and increased Brn3a levels, it failed to block HSP70 degradation. Unlike SOD1 protein which was reduced, catalase protein levels increased after I/R. Psalmotoxin-1, although not affecting SOD1 and GPX4, increased catalase levels significantly. Psalmotoxin-1 also increased RBPMS-labeled RGCs following I/R as judged by immunohistochemistry of retinal flat mounts. Finally, psalmotoxin-1 enhanced the amplitude of PERG following I/R, suggesting partial rescue of RGC function. Psalmotoxin-1 appears to exert a neuroprotective effect under ischemic insults and targeting inhibition of ASICs may represent a

  5. Acid-sensing ion channels (ASICs) in mouse skeletal muscle afferents are heteromers composed of ASIC1a, ASIC2, and ASIC3 subunits

    Science.gov (United States)

    Gautam, Mamta; Benson, Christopher J.

    2013-01-01

    Acid-sensing ion channels (ASICs) are expressed in skeletal muscle afferents, in which they sense extracellular acidosis and other metabolites released during ischemia and exercise. ASICs are formed as homotrimers or heterotrimers of several isoforms (ASIC1a, ASIC1b, ASIC2a, ASIC2b, and ASIC3), with each channel displaying distinct properties. To dissect the ASIC composition in muscle afferents, we used whole-cell patch-clamp recordings to study the properties of acid-evoked currents (amplitude, pH sensitivity, the kinetics of desensitization and recovery from desensitization, and pharmacological modulation) in isolated, labeled mouse muscle afferents from wild-type (C57BL/6J) and specific ASIC−/− mice. We found that ASIC-like currents in wild-type muscle afferents displayed fast desensitization, indicating that they are carried by heteromeric channels. Currents from ASIC1a−/− muscle afferents were less pH-sensitive and displayed faster recovery, currents from ASIC2−/− mice showed diminished potentiation by zinc, and currents from ASIC3−/− mice displayed slower desensitization than those from wild-type mice. Finally, ASIC-like currents were absent from triple-null mice lacking ASIC1a, ASIC2a, and ASIC3. We conclude that ASIC1a, ASIC2a, and ASIC3 heteromers are the principle channels in skeletal muscle afferents. These results will help us understand the role of ASICs in exercise physiology and provide a molecular target for potential drug therapies to treat muscle pain.—Gautam, M., Benson, C. J. Acid-sensing ion channels (ASICs) in mouse skeletal muscle afferents are heteromers composed of ASIC1a, ASIC2, and ASIC3 subunits. PMID:23109675

  6. Two novel penetrating coordination polymers based on flexible S-containing dicarboxylate acid with sensing properties towards Fe3+ and Cr2O72- ions

    Science.gov (United States)

    Chen, Zhiwei; Mi, Xiuna; Wang, Suna; Lu, Jing; Li, Yunwu; Li, Dacheng; Dou, Jianmin

    2018-05-01

    Two new coordination polymers (CPs), namely, {[Zn(L)(bpp)]·DMF}n (1) and {[Zn(L)(bpe)]·DMF}n (2) (L = 2,2'-[benzene-1,3-diylbis(methanediylsulfanediyl)]dibenzoic acid, bpp= 1,3-bis(4-pyridyl)propane, bpe = 1,2-Bis(4-pyridyl)ethylene, DMF = N,N-Dimethylformamide), have been solvothermally synthesized and fully characterized. Complex 1 displays a 2D→2D three-fold"false" interpenetrating structure while complex 2 possesses a novel 3-D 4-connected structure with fascinating self-penetrating moieties. The luminescence studies reveal that these complexes exhibited excellent selectivity for Fe3+ and Cr2O72- ions in DMF. The sensing mechanism was investigated through PXRD, XPS , EDS mapping measurements, and discussed in details.

  7. α-Amino Acid Derived Benzimidazole-Linked Rhodamines: A Case of Substitution Effect at the Amino Acid Site toward Spiro Ring Opening for Selective Sensing of Al3+ Ions.

    Science.gov (United States)

    Majumdar, Anupam; Mondal, Subhendu; Daniliuc, Constantin G; Sahu, Debashis; Ganguly, Bishwajit; Ghosh, Sourav; Ghosh, Utpal; Ghosh, Kumaresh

    2017-08-07

    α-Amino acid derived benzimidazole-linked rhodamines have been synthesized, and their metal ion sensing properties have been evaluated. Experimentally, l-valine- and l-phenylglycine-derived benzimidazole-based rhodamines 1 and 2 selectively recognize Al 3+ ion in aqueous CH 3 CN (CH 3 CN/H 2 O 4/1 v/v, 10 mM tris HCl buffer, pH 7.0) over the other cations by exhibiting color and "turn-on" emission changes. In contrast, glycine-derived benzimidazole 3 remains silent in the recognition event and emphasizes the role of α-substitution of amino acid undertaken in the design. The fact has been addressed on the basis of the single-crystal X-ray structures and theoretical calculations. Moreover, pink 1·Al 3+ and 2·Al 3+ ensembles selectively sensed F - ions over other halides through a discharge of color. Importantly, compounds 1 and 2 are cell permeable and have been used as imaging reagents for the detection of Al 3+ uptake in human lung carcinoma cell line A549.

  8. Nanopore Device for Reversible Ion and Molecule Sensing or Migration

    Science.gov (United States)

    Pourmand, Nader (Inventor); Vilozny, Boaz (Inventor); Actis, Paolo (Inventor); Seger, R. Adam (Inventor); Singaram, Bakthan (Inventor)

    2015-01-01

    Disclosed are methods and devices for detection of ion migration and binding, utilizing a nanopipette adapted for use in an electrochemical sensing circuit. The nanopipette may be functionalized on its interior bore with metal chelators for binding and sensing metal ions or other specific binding molecules such as boronic acid for binding and sensing glucose. Such a functionalized nanopipette is comprised in an electrical sensor that detects when the nanopipette selectively and reversibly binds ions or small molecules. Also disclosed is a nanoreactor, comprising a nanopipette, for controlling precipitation in aqueous solutions by voltage-directed ion migration, wherein ions may be directed out of the interior bore by a repulsing charge in the bore.

  9. Dural afferents express acid-sensing ion channels: a role for decreased meningeal pH in migraine headache.

    Science.gov (United States)

    Yan, Jin; Edelmayer, Rebecca M; Wei, Xiaomei; De Felice, Milena; Porreca, Frank; Dussor, Gregory

    2011-01-01

    Migraine headache is one of the most common neurological disorders. The pathological conditions that directly initiate afferent pain signaling are poorly understood. In trigeminal neurons retrogradely labeled from the cranial meninges, we have recorded pH-evoked currents using whole-cell patch-clamp electrophysiology. Approximately 80% of dural-afferent neurons responded to a pH 6.0 application with a rapidly activating and rapidly desensitizing ASIC-like current that often exceeded 20nA in amplitude. Inward currents were observed in response to a wide range of pH values and 30% of the neurons exhibited inward currents at pH 7.1. These currents led to action potentials in 53%, 30% and 7% of the dural afferents at pH 6.8, 6.9 and 7.0, respectively. Small decreases in extracellular pH were also able to generate sustained window currents and sustained membrane depolarizations. Amiloride, a non-specific blocker of ASIC channels, inhibited the peak currents evoked upon application of decreased pH while no inhibition was observed upon application of TRPV1 antagonists. The desensitization time constant of pH 6.0-evoked currents in the majority of dural afferents was less than 500ms which is consistent with that reported for ASIC3 homomeric or heteromeric channels. Finally, application of pH 5.0 synthetic-interstitial fluid to the dura produced significant decreases in facial and hind-paw withdrawal threshold, an effect blocked by amiloride but not TRPV1 antagonists, suggesting that ASIC activation produces migraine-related behavior in vivo. These data provide a cellular mechanism by which decreased pH in the meninges following ischemic or inflammatory events directly excites afferent pain-sensing neurons potentially contributing to migraine headache. Copyright © 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  10. Enhanced photoresponsive polyethyleneimine/citric acid co-carbonized dots for facile and selective sensing and intracellular imaging of cobalt ions at physiologic pH

    International Nuclear Information System (INIS)

    Zou, Wen-Sheng; Zhao, Qing-Chun; Zhang, Jun; Chen, Xiao-Ming; Wang, Xiu-Fang; Zhao, Lin; Chen, Shao-Hua; Wang, Ya-Qin

    2017-01-01

    Whether as an important biological element or as a radioactive source/medicine, the monitoring of trace levels of cobalt ions (Co) has become a non-negligible factor for human health and green environment. Current technologies for the detection of Co are cost-expensive and time-consuming, and require cumbersome sample pretreatment process. Herein a novel sensing platform has been developed for Co detection based on the quenching of the enhanced fluorescence signal of polyamine functionalized C-dots. Amine groups at the surface of the C-dots can capture Zn"2"+/Cd"2"+ to form coordination compound, which can inhibit the photoinduced electron transfer pathways of C-dots and then induce the fluorescence enhancement of the C-dots by ∼80% margin. Also, Co interacts with these amine groups to form an absorbent complex, which can strongly quench the enhanced fluorescence of C-dots via an inner filter effect. This C-dots-based probe showed a wide linear response to Co with a concentration ranging from 0.012 to 12 μM, and a detection limit of 8.0 nM and RSD of 5.7% (n = 5). Significantly, the C-Dots exhibit excellent properties, such as negligible cytotoxicity, excellent biocompatibility, low-cost and high photostability, etc., which make C-dots favorable for label-free monitoring of Co and then successfully applied to the confocal imaging of intracellular Co. - Highlights: • Polyethyleneimine/citric acid co-carbonized dots were prepared. • Zn"2"+ can enhance fluorescence of C-dots by inhibiting PET pathways. • Co"2"+ can quench the enhanced fluorescence by an inner filter effect. • Bioprobe has been established for intracellular imaging Co.

  11. Enhanced photoresponsive polyethyleneimine/citric acid co-carbonized dots for facile and selective sensing and intracellular imaging of cobalt ions at physiologic pH

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Wen-Sheng, E-mail: wszou@ahjzu.edu.cn; Zhao, Qing-Chun; Zhang, Jun; Chen, Xiao-Ming; Wang, Xiu-Fang; Zhao, Lin; Chen, Shao-Hua; Wang, Ya-Qin, E-mail: yqwang@ahjzu.edu.cn

    2017-06-01

    Whether as an important biological element or as a radioactive source/medicine, the monitoring of trace levels of cobalt ions (Co) has become a non-negligible factor for human health and green environment. Current technologies for the detection of Co are cost-expensive and time-consuming, and require cumbersome sample pretreatment process. Herein a novel sensing platform has been developed for Co detection based on the quenching of the enhanced fluorescence signal of polyamine functionalized C-dots. Amine groups at the surface of the C-dots can capture Zn{sup 2+}/Cd{sup 2+} to form coordination compound, which can inhibit the photoinduced electron transfer pathways of C-dots and then induce the fluorescence enhancement of the C-dots by ∼80% margin. Also, Co interacts with these amine groups to form an absorbent complex, which can strongly quench the enhanced fluorescence of C-dots via an inner filter effect. This C-dots-based probe showed a wide linear response to Co with a concentration ranging from 0.012 to 12 μM, and a detection limit of 8.0 nM and RSD of 5.7% (n = 5). Significantly, the C-Dots exhibit excellent properties, such as negligible cytotoxicity, excellent biocompatibility, low-cost and high photostability, etc., which make C-dots favorable for label-free monitoring of Co and then successfully applied to the confocal imaging of intracellular Co. - Highlights: • Polyethyleneimine/citric acid co-carbonized dots were prepared. • Zn{sup 2+} can enhance fluorescence of C-dots by inhibiting PET pathways. • Co{sup 2+} can quench the enhanced fluorescence by an inner filter effect. • Bioprobe has been established for intracellular imaging Co.

  12. Modeling ion sensing in molecular electronics

    International Nuclear Information System (INIS)

    Chen, Caroline J.; Smeu, Manuel; Ratner, Mark A.

    2014-01-01

    We examine the ability of molecules to sense ions by measuring the change in molecular conductance in the presence of such charged species. The detection of protons (H + ), alkali metal cations (M + ), calcium ions (Ca 2+ ), and hydronium ions (H 3 O + ) is considered. Density functional theory (DFT) is used within the Keldysh non-equilibrium Green's function framework (NEGF) to model electron transport properties of quinolinedithiol (QDT, C 9 H 7 NS 2 ), bridging Al electrodes. The geometry of the transport region is relaxed with DFT. The transport properties of the device are modeled with NEGF-DFT to determine if this device can distinguish among the M + + QDT species containing monovalent cations, where M + = H + , Li + , Na + , or K + . Because of the asymmetry of QDT in between the two electrodes, both positive and negative biases are considered. The electron transmission function and conductance properties are simulated for electrode biases in the range from −0.5 V to 0.5 V at increments of 0.1 V. Scattering state analysis is used to determine the molecular orbitals that are the main contributors to the peaks in the transmission function near the Fermi level of the electrodes, and current-voltage relationships are obtained. The results show that QDT can be used as a proton detector by measuring transport through it and can conceivably act as a pH sensor in solutions. In addition, QDT may be able to distinguish among different monovalent species. This work suggests an approach to design modern molecular electronic conductance sensors with high sensitivity and specificity using well-established quantum chemistry

  13. The expression profile of acid-sensing ion channel (ASIC) subunits ASIC1a, ASIC1b, ASIC2a, ASIC2b, and ASIC3 in the esophageal vagal afferent nerve subtypes.

    Science.gov (United States)

    Dusenkova, Svetlana; Ru, Fei; Surdenikova, Lenka; Nassenstein, Christina; Hatok, Jozef; Dusenka, Robert; Banovcin, Peter; Kliment, Jan; Tatar, Milos; Kollarik, Marian

    2014-11-01

    Acid-sensing ion channels (ASICs) have been implicated in esophageal acid sensing and mechanotransduction. However, insufficient knowledge of ASIC subunit expression profile in esophageal afferent nerves hampers the understanding of their role. This knowledge is essential because ASIC subunits form heteromultimeric channels with distinct functional properties. We hypothesized that the esophageal putative nociceptive C-fiber nerves (transient receptor potential vanilloid 1, TRPV1-positive) express multiple ASIC subunits and that the ASIC expression profile differs between the nodose TRPV1-positive subtype developmentally derived from placodes and the jugular TRPV1-positive subtype derived from neural crest. We performed single cell RT-PCR on the vagal afferent neurons retrogradely labeled from the esophagus. In the guinea pig, nearly all (90%-95%) nodose and jugular esophageal TRPV1-positive neurons expressed ASICs, most often in a combination (65-75%). ASIC1, ASIC2, and ASIC3 were expressed in 65-75%, 55-70%, and 70%, respectively, of both nodose and jugular TRPV1-positive neurons. The ASIC1 splice variants ASIC1a and ASIC1b and the ASIC2 splice variant ASIC2b were similarly expressed in both nodose and jugular TRPV1-positive neurons. However, ASIC2a was found exclusively in the nodose neurons. In contrast to guinea pig, ASIC3 was almost absent from the mouse vagal esophageal TRPV1-positive neurons. However, ASIC3 was similarly expressed in the nonnociceptive TRPV1-negative (tension mechanoreceptors) neurons in both species. We conclude that the majority of esophageal vagal nociceptive neurons express multiple ASIC subunits. The placode-derived nodose neurons selectively express ASIC2a, known to substantially reduce acid sensitivity of ASIC heteromultimers. ASIC3 is expressed in the guinea pig but not in the mouse vagal esophageal TRPV1-positive neurons, indicating species differences in ASIC expression. Copyright © 2014 the American Physiological Society.

  14. A new ion sensing deep atomic force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Drake, Barney; Randall, Connor; Bridges, Daniel; Hansma, Paul K. [Department of Physics, University of California, Santa Barbara, California 93106 (United States)

    2014-08-15

    Here we describe a new deep atomic force microscope (AFM) capable of ion sensing. A novel probe assembly incorporates a micropipette that can be used both for sensing ion currents and as the tip for AFM imaging. The key advance of this instrument over previous ion sensing AFMs is that it uses conventional micropipettes in a novel suspension system. This paper focuses on sensing the ion current passively while using force feedback for the operation of the AFM in contact mode. Two images are obtained simultaneously: (1) an AFM topography image and (2) an ion current image. As an example, two images of a MEMS device with a microchannel show peaks in the ion current as the pipette tip goes over the edges of the channel. This ion sensing AFM can also be used in other modes including tapping mode with force feedback as well as in non-contact mode by utilizing the ion current for feedback, as in scanning ion conductance microscopy. The instrument is gentle enough to be used on some biological samples such as plant leaves.

  15. Fluorescent sensing and determination of mercury (II) ions in water ...

    African Journals Online (AJOL)

    In this study we report on a fluorescent sensing probe based on a naphthyl azo dye modified dibenzo-18-crown-6-ether (DB18C6) for the detection and determination of mercury (II) ions in water. The probe showed high sensitivity and selectivity towards the mercury (II) ion among various alkali, alkaline earth, and transition ...

  16. Combination of Ambiguous and Unambiguous Data in the Restraint-driven Docking of Flexible Peptides with HADDOCK: The Binding of the Spider Toxin PcTx1 to the Acid Sensing Ion Channel (ASIC) 1a.

    Science.gov (United States)

    Deplazes, Evelyne; Davies, Josephine; Bonvin, Alexandre M J J; King, Glenn F; Mark, Alan E

    2016-01-25

    Peptides that bind to ion channels have attracted much interest as potential lead molecules for the development of new drugs and insecticides. However, the structure determination of large peptide-channel complexes using experimental methods is challenging. Thus structural models are often derived from combining experimental information with restraint-driven docking approaches. Using the complex formed by the venom peptide PcTx1 and the acid sensing ion channel (ASIC) 1a as a case study, we have examined the effect of different combinations of restraints and input structures on the statistical likelihood of (a) correctly predicting the structure of the binding interface and (b) the ability to predict which residues are involved in specific pairwise peptide-channel interactions. For this, we have analyzed over 200,000 water-refined docked structures obtained with various amounts and types of restraints of the peptide-channel complex predicted using the docking program HADDOCK. We found that increasing the number of restraints or even the use of pairwise interaction data resulted in only a modest improvement in the likelihood of finding a structure within a given accuracy. This suggests that shape complementarity and the force field make a large contribution to the accuracy of the predicted structure. The results also showed that there are large variations in the accuracy of the predicted structure depending on the precise combination of residues used as restraints. Finally, we reflect on the limitations of relying on geometric criteria such as root-mean square deviations to assess the accuracy of docking procedures. We propose that in addition to currently used measures, the likelihood of finding a structure within a given level of accuracy should be also used to evaluate docking methods.

  17. Global versus local mechanisms of temperature sensing in ion channels.

    Science.gov (United States)

    Arrigoni, Cristina; Minor, Daniel L

    2018-05-01

    Ion channels turn diverse types of inputs, ranging from neurotransmitters to physical forces, into electrical signals. Channel responses to ligands generally rely on binding to discrete sensor domains that are coupled to the portion of the channel responsible for ion permeation. By contrast, sensing physical cues such as voltage, pressure, and temperature arises from more varied mechanisms. Voltage is commonly sensed by a local, domain-based strategy, whereas the predominant paradigm for pressure sensing employs a global response in channel structure to membrane tension changes. Temperature sensing has been the most challenging response to understand and whether discrete sensor domains exist for pressure and temperature has been the subject of much investigation and debate. Recent exciting advances have uncovered discrete sensor modules for pressure and temperature in force-sensitive and thermal-sensitive ion channels, respectively. In particular, characterization of bacterial voltage-gated sodium channel (BacNa V ) thermal responses has identified a coiled-coil thermosensor that controls channel function through a temperature-dependent unfolding event. This coiled-coil thermosensor blueprint recurs in other temperature sensitive ion channels and thermosensitive proteins. Together with the identification of ion channel pressure sensing domains, these examples demonstrate that "local" domain-based solutions for sensing force and temperature exist and highlight the diversity of both global and local strategies that channels use to sense physical inputs. The modular nature of these newly discovered physical signal sensors provides opportunities to engineer novel pressure-sensitive and thermosensitive proteins and raises new questions about how such modular sensors may have evolved and empowered ion channel pores with new sensibilities.

  18. Promiscuous Seven Transmembrane Receptors Sensing L-α-amino Acids

    DEFF Research Database (Denmark)

    Smajilovic, Sanela; Wellendorph, Petrine; Bräuner-Osborne, Hans

    2014-01-01

    A number of nutrient sensing seven trans-membrane (7TM) receptors have been identified and characterized over the past few years. While the sensing mechanisms to carbohydrates and free fatty acids are well understood, the molecular basis of amino acid sensing has recently come to the limelight....... The present review describes the current status of promiscuous L-α-amino acid sensors, the calcium sensing receptor (CaSR), the GPRC6A receptor, the T1R1/T1R3 receptor and also their molecular pharmacology, expression pattern and physiological significance....

  19. Synthesis, characterization and nitrite ion sensing performance of reclaimable composite samples through a core-shell structure

    Science.gov (United States)

    Cui, Xiao; Yuqing, Zhao; Cui, Jiantao; Zheng, Qian; Bo, Wang

    2018-02-01

    The following paper reported and discussed a nitrite ion optical sensing platform based on a core-shell structure, using superamagnetic nanoparticles as the core, a silica molecular sieve MCM-41 as the shell and two rhodamine derivatives as probe, respectively. This superamagnetic core made this sensing platform reclaimable after finishing nitrite ion sensing procedure. This sensing platform was carefully characterized by means of electron microscopy images, porous structure analysis, magnetic response, IR spectra and thermal stability analysis. Detailed analysis suggested that the emission of these composite samples was quenchable by nitrite ion, showing emission turn off effect. A static sensing mechanism based on an additive reaction between chemosensors and nitrite ion was proposed. These composite samples followed Demas quenching equation against different nitrite ion concentrations. Limit of detection value was obtained as low as 0.4 μM. It was found that, after being quenched by nitrite ion, these composite samples could be reclaimed and recovered by sulphamic acid, confirming their recyclability.

  20. Highly sensitive urea sensing with ion-irradiated polymer foils

    International Nuclear Information System (INIS)

    Fink, Dietmar; Muñoz Hernandez, Gerardo; Alfonta, Lital

    2012-01-01

    Recently we prepared urea-sensors by attaching urease to the inner walls of etched ion tracks within thin polymer foil. Here, alternative track-based sensor configurations are examined where the enzyme remained in solution. The conductivities of systems consisting of two parallel irradiated polymer foils and confining different urea/urease mixtures in between were examined. The correlations between conductivity and urea concentration differed strongly for foils with unetched and etched tracks, which points at different sensing mechanisms – tentatively attributed to the adsorption of enzymatic reaction products on the latent track entrances and to the enhanced conductivity of reaction product-filled etched tracks, respectively. All examined systems enable in principle, urea sensing. They point at the possibility of sensor cascade construction for more sensitive or selective sensor systems.

  1. Analysis of iodinated quorum sensing peptides by LC–UV/ESI ion trap mass spectrometry

    Directory of Open Access Journals (Sweden)

    Yorick Janssens

    2018-02-01

    Full Text Available Five different quorum sensing peptides (QSP were iodinated using different iodination techniques. These iodinated peptides were analyzed using a C18 reversed phase HPLC system, applying a linear gradient of water and acetonitrile containing 0.1% (m/v formic acid as mobile phase. Electrospray ionization (ESI ion trap mass spectrometry was used for the identification of the modified peptides, while semi-quantification was performed using total ion current (TIC spectra. Non-iodinated peptides and mono- and di-iodinated peptides (NIP, MIP and DIP respectively were well separated and eluted in that order. Depending on the used iodination method, iodination yields varied from low (2% to high (57%.

  2. Amino acids grafting of Ar+ ions modified PE

    International Nuclear Information System (INIS)

    Svorcik, V.; Hnatowicz, V.; Stopka, P.; Bacakova, L.; Heitz, J.; Oechsner, R.; Ryssel, H.

    2001-01-01

    Polyethylene (PE) was irradiated with 63 keV Ar + ions to the fluences from 1x10 12 to 3x10 15 cm -2 and then grafted at room temperature from water solution with amino acids (alanine, leucine). Using various spectroscopic techniques (UV-VIS, FTIR, RBS and EPR) it was shown that the amino acids penetrate into PE where they are eventually captured either on double bonds or on free radicals created by the ion irradiation. Grafting with amino acids in the whole specimen layer modified by irradiation is observed. The ion-beam-modified and amino-acid grafted PE is supposed to exhibit increased biocompatibility. (author)

  3. Construction of three lanthanide metal-organic frameworks: Synthesis, structure, magnetic properties and highly selective sensing of metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiu-Mei, E-mail: zhangxiumeilb@126.com; Li, Peng; Gao, Wei; Liu, Feng; Liu, Jie-Ping

    2016-12-15

    Three lanthanide metal-organic frameworks (Ln-MOFs), [Ln(TZI)(H{sub 2}O){sub 4}]·3H{sub 2}O (Ln=Gd (1) and Tb (2) and Dy (3), H{sub 3}TZI=5-(1H-tetrazol-5-yl)isophthalic acid), have been synthesized under hydrothermal conditions. Single crystal X-ray diffraction reveals that 1–3 are isostructural and display a 1D double chain based on dinuclear motifs with (μ-COO){sub 2} double bridges. Magnetic studies indicate antiferromagnetic interactions in 1, ferromagnetic interactions in 2 and 3. Furthermore, compound 3 displays a slow relaxation behavior. Compound 2 exhibits intense characteristic green emission of Tb(III) ions in the solid state, which can be observed by the naked eye under UV light. Interestingly, 2 can selectively sense Pb{sup 2+} and Fe{sup 3+} ions through luminescence enhancement and quenching, respectively. The luminescence quenching mechanisms have been investigated in detail. The study on luminescence Ln-MOFs as a probe for sensing Pb{sup 2+} and Fe{sup 3+} ions is exceedingly rare example. - Graphical abstract: Three Ln-MOFs were successfully synthesized using a 5-(1H-tetrazol-5-yl)isophthalic acid ligand. They displays different magnetic behavior. Especially, the Dy(III) compound slow relaxation behavior. Interestingly, the Tb(III) compound can selectively sense Pb{sup 2+} and Fe{sup 3+} ions through luminescence enhancement and quenching, respectively. - Highlights: • Three Ln-MOFs with tetrazolate dicarboxylate ligand. • Dy(III) compound displays slow relaxation behavior. • The Tb(III) compound shows highly selective luminescence sensing of the Fe{sup 3+} and Pb{sup 2+} ions.

  4. Extracting metal ions with diphosphonic acid, or derivative thereof

    Science.gov (United States)

    Horwitz, Earl P.; Gatrone, Ralph C.; Nash, Kenneth L.

    1994-01-01

    Thermodynamically-unstable complexing agents which are diphosphonic acids and diphosphonic acid derivatives (or sulphur containing analogs), like carboxyhydroxymethanediphosphonic acid and vinylidene-1,1-diphosphonic acid, are capable of complexing with metal ions, and especially metal ions in the II, III, IV, V and VI oxidation states, to form stable, water-soluble metal ion complexes in moderately alkaline to highly-acidic media. However, the complexing agents can be decomposed, under mild conditions, into non-organic compounds which, for many purposes are environmentally-nondamaging compounds thereby degrading the complex and releasing the metal ion for disposal or recovery. Uses for such complexing agents as well as methods for their manufacture are also described.

  5. Extracting metal ions with diphosphonic acid, or derivative thereof

    Science.gov (United States)

    Horwitz, E.P.; Gatrone, R.C.; Nash, K.L.

    1994-07-26

    Thermodynamically-unstable complexing agents which are diphosphonic acids and diphosphonic acid derivatives (or sulfur containing analogs), like carboxyhydroxymethanediphosphonic acid and vinylidene-1,1-diphosphonic acid, are capable of complexing with metal ions, and especially metal ions in the II, III, IV, V and VI oxidation states, to form stable, water-soluble metal ion complexes in moderately alkaline to highly-acidic media. However, the complexing agents can be decomposed, under mild conditions, into non-organic compounds which, for many purposes are environmentally-nondamaging compounds thereby degrading the complex and releasing the metal ion for disposal or recovery. Uses for such complexing agents as well as methods for their manufacture are also described. 1 fig.

  6. Remote sensing of acid sulfate soils using multispectral and gamma-ray data

    International Nuclear Information System (INIS)

    Bierwirth, P.N.; Graham, T.L.

    1998-01-01

    Acid sulfate soils are a significant environmental problem in coastal regions of Australia. Drainage and disturbance of coastal lands can result in acid soil degradation and the release of sulfuric acid and toxic metals into coastal waters. Remote sensing can provide a useful tool for detection of these soils and monitoring of their disturbance. As acid sulfate soils become oxidised with exposure to air, iron-minerals are produced and precipitate at the surface. This results from the breakdown of pyrite to form hydrated iron minerals and elemental sulfur, the oxidation of which produces acidity. The concentration of iron minerals at the surface can be an indicator of the level of acid sulfate soil activity in the near subsurface. These iron minerals include goethite, ferrihydrite and jarosite. Space-borne remote sensing scanners such as Landsat TM are capable of detecting iron minerals as a result of ferric ion absorption of solar radiation. Hyperspectral scanners are capable of further discrimination of individual minerals. This paper will discuss spectral characteristics of active acid sulfate soils and demonstrate the use of spectral unmixing algorithms on Landsat TM to detect problem areas at the surface. This method matches multispectral data to material reflectance-spectra known as end-members. These end-members or materials are then resolved mathematically as to their respective contributions to the overall reflectance (Bierwirth, 1990). In this way, abundances for particular materials can be derived.Digital elevation data was used to distinguish between the iron minerals due to weathering of bedrock in upland areas and acid sulfate soils on the plains. Also, the results of a high resolution (200m linespacing) airborne gamma-ray survey are presented. This data senses the concentration of radioelements down to about 40 cm depth and is largely unaffected by vegetation. Concentrations of gamma-emitting elements can indicate the type and depth of alluvium that

  7. Pyrene-Phosphonate Conjugate: Aggregation-Induced Enhanced Emission, and Selective Fe3+ Ions Sensing Properties

    Directory of Open Access Journals (Sweden)

    Sachin D. Padghan

    2017-08-01

    Full Text Available A new pyrene-phosphonate colorimetric receptor 1 has been designed and synthesized in a one-step process via amide bond formation between pyrene butyric acid chloride and phosphonate-appended aniline. The pyrene-phosphonate receptor 1 showed aggregation-induced enhanced emission (AIEE properties in water/acetonitrile (ACN solutions. Dynamic light scattering (DLS characterization revealed that the aggregates of receptor 1 at 80% water fraction have an average size of ≈142 nm. Field emission scanning electron microscopy (FE-SEM analysis confirmed the formation of spherical aggregates upon solvent evaporation. The sensing properties of receptor 1 were investigated by UV-vis, fluorescence emission spectroscopy, and other optical methods. Among the tested metal ions, receptor 1 is capable of recognizing the Fe3+ ion selectively. The changes in spectral measurements were explained on the basis of complex formation. The composition of receptor 1 and Fe3+ ions was determined by using Job’s plot and found to be 1:1. The receptor 1–Fe3+ complex showed a reversible UV-vis response in the presence of EDTA.

  8. Ion sensing properties of vanadium/tungsten mixed oxides

    International Nuclear Information System (INIS)

    Guidelli, Eder Jose; Guerra, Elidia Maria; Mulato, Marcelo

    2011-01-01

    Vanadium/tungsten mixed oxide (V 2 O 5 /WO 3 ) sensing membranes were deposited on glassy carbon substrates and used as the H + sensor of the extended gate field effect transistor (EGFET) device. X-ray diffractograms indicated a decrease of the interplanar spacing of V 2 O 5 after the insertion of WO 3 revealing that the lamellar structure is under compressive stress. The crystallinity increases with increasing WO 3 molar ratio. The film is not homogeneous, with more WO 3 material sitting at the surface. This influences the response of pH sensors using the EGFET configuration. The maximum sensitivity of 68 mV pH -1 was obtained for the sample with 5% WO 3 molar ratio. For higher WO 3 molar ratios, the behavior is not linear. It can be concluded that V 2 O 5 dominates for acidic solutions while WO 3 dominates for basic solutions. Therefore, the mixed oxide with low amount of WO 3 is the main candidate for further use as biosensor.

  9. MOLECULAR PATHOPHYSIOLOGY AND PHARMACOLOGY OF THE VOLTAGE-SENSING DOMAIN OF NEURONAL ION CHANNELS

    Directory of Open Access Journals (Sweden)

    Francesco eMiceli

    2015-07-01

    Full Text Available Voltage-gated ion channels (VGIC are membrane proteins that switch from a closed to open state in response to changes in membrane potential, thus enabling ion fluxes across the cell membranes. The mechanism that regulate the structural rearrangements occurring in VGIC in response to changes in membrane potential still remains one of the most challenging topic of modern biophysics. Na+, Ca2+ and K+ voltage-gated channels are structurally formed by the assembly of four similar domains, each comprising six transmembrane segments. Each domain can be divided in two main regions: the Pore Module (PM and the Voltage-Sensing Module (VSM. The PM (helices S5 and S6 and intervening linker is responsible for gate opening and ion selectivity; by contrast, the VSM, comprising the first four transmembrane helices (S1-S4, undergoes the first conformational changes in response to membrane voltage. In particular, the S4 segment of each domain, which contains several positively charged residues interspersed with hydrophobic amino acids, is located within the membrane electric field and plays an essential role in voltage sensing. In neurons, specific gating properties of each channel subtype underlie a variety of biological events, ranging from the generation and propagation of electrical impulses, to the secretion of neurotransmitters, to the regulation of gene expression. Given the important functional role played by the VSM in neuronal VGICs, it is not surprising that various VSM mutations affecting the gating process of these channels are responsible for human diseases, and that compounds acting on the VSM have emerged as important investigational tools with great therapeutic potential. In the present review we will briefly describe the most recent discoveries concerning how the VSM exerts its function, how genetically inherited diseases caused by mutations occurring in the VSM affects gating in VGICs, and how several classes of drugs and toxins selectively

  10. Molecular pathophysiology and pharmacology of the voltage-sensing module of neuronal ion channels.

    Science.gov (United States)

    Miceli, Francesco; Soldovieri, Maria Virginia; Ambrosino, Paolo; De Maria, Michela; Manocchio, Laura; Medoro, Alessandro; Taglialatela, Maurizio

    2015-01-01

    Voltage-gated ion channels (VGICs) are membrane proteins that switch from a closed to open state in response to changes in membrane potential, thus enabling ion fluxes across the cell membranes. The mechanism that regulate the structural rearrangements occurring in VGICs in response to changes in membrane potential still remains one of the most challenging topic of modern biophysics. Na(+), Ca(2+) and K(+) voltage-gated channels are structurally formed by the assembly of four similar domains, each comprising six transmembrane segments. Each domain can be divided into two main regions: the Pore Module (PM) and the Voltage-Sensing Module (VSM). The PM (helices S5 and S6 and intervening linker) is responsible for gate opening and ion selectivity; by contrast, the VSM, comprising the first four transmembrane helices (S1-S4), undergoes the first conformational changes in response to membrane voltage variations. In particular, the S4 segment of each domain, which contains several positively charged residues interspersed with hydrophobic amino acids, is located within the membrane electric field and plays an essential role in voltage sensing. In neurons, specific gating properties of each channel subtype underlie a variety of biological events, ranging from the generation and propagation of electrical impulses, to the secretion of neurotransmitters and to the regulation of gene expression. Given the important functional role played by the VSM in neuronal VGICs, it is not surprising that various VSM mutations affecting the gating process of these channels are responsible for human diseases, and that compounds acting on the VSM have emerged as important investigational tools with great therapeutic potential. In the present review we will briefly describe the most recent discoveries concerning how the VSM exerts its function, how genetically inherited diseases caused by mutations occurring in the VSM affects gating in VGICs, and how several classes of drugs and toxins

  11. Hydrolysis and ion exchange of titania nanoparticles towards large-scale titania and titanate nanobelts for gas sensing applications

    International Nuclear Information System (INIS)

    Bela, Somaiah; Ho, Ghim Wei; Wong, Andrew See Weng

    2010-01-01

    One-dimensional titanate and titania nanostructures are prepared by hydrothermal method from titania nanoparticles precursor via hydrolysis and ion exchange processes. The formation mechanism and the reaction process of the nanobelts are elucidated. The effects of the NaOH concentration, HCl leaching duration and the calcination temperature on the morphology and chemical composition of the produced nanobelts are investigated. Na + ions of the titanate nanobelts can be effectively removed by longer acid leaching and neutralization process and transformed into metastable hydrogen titanate compound. A hybrid hydrogen titanate and anatase titania nanobelts can be obtained under dehydration process of 500 0 C. The nanobelts are produced in gram quantities and easily made into nanostructure paper for the bulk study on their electrical and sensing properties. The sensing properties of the nanobelts sheet are tested and exhibited response to H 2 gas.

  12. Determination of Carboxylic Acids and Water-soluble Inorganic Ions ...

    African Journals Online (AJOL)

    NICO

    radiation balance.4,5 Major water-soluble inorganic ions are associated with atmospheric ... molecular weight carboxylic acids in aerosol samples collected from a rural ... include biomass burning, agriculture, livestock and soil dust. Tropical ...

  13. Determination of Carboxylic Acids and Water-soluble Inorganic Ions ...

    African Journals Online (AJOL)

    Atmospheric aerosol samples of PM2.5 and PM10 were collected in April–May 2011 from a rural site in Tanzania and analyzed for water-soluble inorganic ions and low molecular weight carboxylic acids using ion chromatography. PM2.5 and PM10 low-volume samplers with quartz fibre filters were deployed and aerosol ...

  14. Recovery of boric acid from ion exchangers

    International Nuclear Information System (INIS)

    Pollock, C.W.

    1976-01-01

    The recovery of boric acid from an anion exchange resin is improved by eluting the boric acid with an aqueous solution of ammonium bicarbonate. The boric acid can be readily purified and concentrated by distilling off the water and ammonium bicarbonate. This process is especially useful for the recovery of boric acid containing a high percentage of 10 B which may be found in some nuclear reactor coolant solutions. 10 claims

  15. Procedure for reducing hydrogen ion concentration in acidic anion eluate

    International Nuclear Information System (INIS)

    Parobek, P.; Baloun, S.; Plevac, S.

    1992-01-01

    A procedure is suggested for reducing the concentration of hydrogen ions in the acidic anionic eluate formed during the separation of uranium. The procedure involves anex elution, precipitation, filtration, precipitate rinsing, and anex rinsing. The procedure is included in the uranium elution process and requires at least one ion exchanger column and at least one tank in the continuous or discontinuous mode. Sparing the neutralizing agent by reducing the hydrogen ion concentration in the acidic anionic eluate is a major asset of this procedure. (Z.S.). 1 fig

  16. Chelating ion exchange with macroreticular hydroxamic acid resins

    International Nuclear Information System (INIS)

    Phillips, R.J.

    1980-01-01

    The synthesis, reactions, and analytical applications of hydroxamic acids, including chelating resins with this functional group, are reviewed. A procedure for attaching N-phenyl hydroxamic acid groups to Amberlite XAD-4 is described. The extraction of 20 metal ions from 2 M hydrochloric acid by this resin is discussed. Conditions for the quantitative extraction and back-extraction of 9 ions are reported. Results are compared with work on solvent extraction with N-phenylbenzohydroxamic acid. Procedures for attaching N-methyl and N-unsubstituted hydroxamic acid groups to Amberlite XAD-4 are described. The N-phenyl, N-methyl, and N-unsubstituted hydroxamic acid resins are compared with respect to metal-ion complexation. The scope of applications for hydroxamic acid resins is investigated by studying the extraction of 19 metal ions as a function of pH. The resins are especially suitable for the extraction of zirconium(IV), titanium(IV), and uranium(IV) from strongly acidic solution. Aluminum(III) is separated from calcium and phosphate by extraction at pH 4. The use of the resins for the purification of reagents, concentration of trace constituents, and chromatographic separation is demonstrated

  17. Complexation of metal ions with humic acid: charge neutralization model

    International Nuclear Information System (INIS)

    Kim, J.I.; Czerwinski, K.R.

    1995-01-01

    A number of different approaches are being used for describing the complexation equilibrium of actinide ions with humic or fulvic acid. The approach chosen and verified experimentally by Tu Muenchen will be discussed with notable examples from experiment. This approach is based on the conception that a given actinide ion is neutralized upon complexation with functional groups of humic or fulvic acid, e.g. carboxylic and phenolic groups, which are known as heterogeneously cross-linked polyelectrolytes. The photon energy transfer experiment with laser light excitation has shown that the actinide ion binding with the functional groups is certainly a chelation process accompanied by metal ion charge neutralization. This fact is in accordance with the experimental evidence of the postulated thermodynamic equilibrium reaction. The experimental results are found to be independent of origin of humic or fulvic acid and applicable for a broad range of pH. (authors). 23 refs., 7 figs., 1 tab

  18. Targeting Cytosolic Nucleic Acid-Sensing Pathways for Cancer Immunotherapies.

    Science.gov (United States)

    Iurescia, Sandra; Fioretti, Daniela; Rinaldi, Monica

    2018-01-01

    The innate immune system provides the first line of defense against pathogen infection though also influences pathways involved in cancer immunosurveillance. The innate immune system relies on a limited set of germ line-encoded sensors termed pattern recognition receptors (PRRs), signaling proteins and immune response factors. Cytosolic receptors mediate recognition of danger damage-associated molecular patterns (DAMPs) signals. Once activated, these sensors trigger multiple signaling cascades, converging on the production of type I interferons and proinflammatory cytokines. Recent studies revealed that PRRs respond to nucleic acids (NA) released by dying, damaged, cancer cells, as danger DAMPs signals, and presence of signaling proteins across cancer types suggests that these signaling mechanisms may be involved in cancer biology. DAMPs play important roles in shaping adaptive immune responses through the activation of innate immune cells and immunological response to danger DAMPs signals is crucial for the host response to cancer and tumor rejection. Furthermore, PRRs mediate the response to NA in several vaccination strategies, including DNA immunization. As route of double-strand DNA intracellular entry, DNA immunization leads to expression of key components of cytosolic NA-sensing pathways. The involvement of NA-sensing mechanisms in the antitumor response makes these pathways attractive drug targets. Natural and synthetic agonists of NA-sensing pathways can trigger cell death in malignant cells, recruit immune cells, such as DCs, CD8 + T cells, and NK cells, into the tumor microenvironment and are being explored as promising adjuvants in cancer immunotherapies. In this minireview, we discuss how cGAS-STING and RIG-I-MAVS pathways have been targeted for cancer treatment in preclinical translational researches. In addition, we present a targeted selection of recent clinical trials employing agonists of cytosolic NA-sensing pathways showing how these pathways

  19. Precipitation of humic acid with divalent ions

    DEFF Research Database (Denmark)

    Andersen, Niels Peder Raj; Mikkelsen, Lene Haugaard; Keiding, Kristian

    2001-01-01

    and Ba2+. The phase diagram model can not account for the observed precipitation in region III and However, in region IV the HA appears to posses colloidal properties, which is supported by precipitation taking place at a constant zeta-potential -21mV with the same amount of added barium ion regardless...

  20. Cation–Anion Interactions within the Nucleic Acid Ion Atmosphere Revealed by Ion Counting

    Science.gov (United States)

    Gebala, Magdalena; Giambasu, George M.; Lipfert, Jan; Bisaria, Namita; Bonilla, Steve; Li, Guangchao; York, Darrin M.; Herschlag, Daniel

    2016-01-01

    The ion atmosphere is a critical structural, dynamic, and energetic component of nucleic acids that profoundly affects their interactions with proteins and ligands. Experimental methods that “count” the number of ions thermodynamically associated with the ion atmosphere allow dissection of energetic properties of the ion atmosphere, and thus provide direct comparison to theoretical results. Previous experiments have focused primarily on the cations that are attracted to nucleic acid polyanions, but have also showed that anions are excluded from the ion atmosphere. Herein, we have systematically explored the properties of anion exclusion, testing the zeroth-order model that anions of different identity are equally excluded due to electrostatic repulsion. Using a series of monovalent salts, we find, surprisingly, that the extent of anion exclusion and cation inclusion significantly depends on salt identity. The differences are prominent at higher concentrations and mirror trends in mean activity coefficients of the electrolyte solutions. Salts with lower activity coefficients exhibit greater accumulation of both cations and anions within the ion atmosphere, strongly suggesting that cation–anion correlation effects are present in the ion atmosphere and need to be accounted for to understand electrostatic interactions of nucleic acids. To test whether the effects of cation–anion correlations extend to nucleic acid kinetics and thermodynamics, we followed the folding of P4–P6, a domain of the Tetrahymena group I ribozyme, via single-molecule fluorescence resonance energy transfer in solutions with different salts. Solutions of identical concentration but lower activity gave slower and less favorable folding. Our results reveal hitherto unknown properties of the ion atmosphere and suggest possible roles of oriented ion pairs or anion-bridged cations in the ion atmosphere for electrolyte solutions of salts with reduced activity. Consideration of these new

  1. Visual sensing of fluoride ions by dipyrrolyl derivatives bearing

    Indian Academy of Sciences (India)

    withdrawing quinone or dicyano functionalities in their architecture permit the detection of fluoride ions under visual (naked-eye) as well as optical (absorption and fluorescence) and electrochemical conditions in organic solvents.

  2. Sensing small neurotransmitter-enzyme interaction with nanoporous gated ion-sensitive field effect transistors.

    Science.gov (United States)

    Kisner, Alexandre; Stockmann, Regina; Jansen, Michael; Yegin, Ugur; Offenhäusser, Andreas; Kubota, Lauro Tatsuo; Mourzina, Yulia

    2012-01-15

    Ion-sensitive field effect transistors with gates having a high density of nanopores were fabricated and employed to sense the neurotransmitter dopamine with high selectivity and detectability at micromolar range. The nanoporous structure of the gates was produced by applying a relatively simple anodizing process, which yielded a porous alumina layer with pores exhibiting a mean diameter ranging from 20 to 35 nm. Gate-source voltages of the transistors demonstrated a pH-dependence that was linear over a wide range and could be understood as changes in surface charges during protonation and deprotonation. The large surface area provided by the pores allowed the physical immobilization of tyrosinase, which is an enzyme that oxidizes dopamine, on the gates of the transistors, and thus, changes the acid-base behavior on their surfaces. Concentration-dependent dopamine interacting with immobilized tyrosinase showed a linear dependence into a physiological range of interest for dopamine concentration in the changes of gate-source voltages. In comparison with previous approaches, a response time relatively fast for detecting dopamine was obtained. Additionally, selectivity assays for other neurotransmitters that are abundantly found in the brain were examined. These results demonstrate that the nanoporous structure of ion-sensitive field effect transistors can easily be used to immobilize specific enzyme that can readily and selectively detect small neurotransmitter molecule based on its acid-base interaction with the receptor. Therefore, it could serve as a technology platform for molecular studies of neurotransmitter-enzyme binding and drugs screening. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Vibrational studies in aqueous solutions. Part II. The acid oxalate ion and oxalic acid

    Science.gov (United States)

    Shippey, T. A.

    1980-08-01

    Assignments for oxalic acid in solution are re-examined. A detailed assignment of the IR and Raman spectra of the acid oxalate ion is presented for the first time. Raman spectroscopy is used to study the first ionization of oxalic acid.

  4. Enhanced quantum sensing with multi-level structures of trapped ions

    DEFF Research Database (Denmark)

    Aharon, N.; Drewsen, Michael; Retzker, A.

    2017-01-01

    , robustness to both external and controller noise is achieved. We consider trapped-ion based implementation via the dipole transitions, which is relevant for several types of ions, such as the $^{40}{\\rm{Ca}}^{+}$, $^{88}{\\rm{Sr}}^{+}$, and the $^{138}{\\rm{Ba}}^{+}$ ions. Taking experimental errors...... of magnitude of the sensitivity. In addition, we present a microwave based sensing scheme that is suitable for ions with a hyperfine structure, such as the $^{9}{\\rm{Be}}^{+}$,$^{25}{\\rm{Mg}}^{+}$,$^{43}{\\rm{Ca}}^{+}$,$^{87}{\\rm{Sr}}^{+}$,$^{137}{\\rm{Ba}}^{+}$,$^{111}{\\rm{Cd}}^{+}$,$^{171}{\\rm...

  5. Phosphinic acid functionalized carbon nanotubes for sensitive and selective sensing of chromium(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Deep, Akash, E-mail: dr.akashdeep@csio.res.in; Sharma, Amit L.; Tuteja, Satish K.; Paul, A.K.

    2014-08-15

    Highlights: • SWCNTs have been conjugated with bis(2,4,4-trimethylpentyl) phosphinic acid (PA/d). • SWCNT-PA/d adduct is demonstrated for electrochemical sensing of Cr(VI). • Linear response is obtained for 0.01–10 ppb Cr(VI). • Sensitivity and the limit of detection are 35 ± 4 nA/ppb and 0.01 ppb, respectively. • Proposed sensing of Cr(VI) is selective with respect to many other metals. - Abstract: Single-walled carbon nanotubes (SWCNTs) have been functionalized with a phosphinic acid derivative ‘bis(2,4,4-trimethylpentyl) phosphinic acid’ (PA/d). It has been achieved by treating the chlorinated SWCNTs with PA/d at 80 °C. Successful functionalization and different nanomaterial properties have been investigated by UV–vis–NIR, FTIR, Raman spectroscopy, AFM and FE-SEM. PA/d conjugated SWCNTs (CNT–PA) are dispersible in some common organic solvents, e.g. CH{sub 2}Cl{sub 2}, DMF, CHCl{sub 3}, and THF. The ‘CNT–PA’ complex was spin-casted on boron doped silicon wafer. Thus fabricated sensing electrode is demonstrated for sensitive and selective electrochemical sensing of chromium(VI) ions. A linear response is obtained over a wide range of Cr(VI) concentration (0.01–10 ppb). The sensor's sensitivity and the limit of detection are observed to be 35 ± 4 nA/ppb and 0.01 ppb, respectively. The practical utility of the proposed sensor is demonstrated by determining the Cr(VI) concentration in an industrial effluent sample and an underground water sample.

  6. Surface functionalization of epitaxial graphene on SiC by ion irradiation for gas sensing application

    International Nuclear Information System (INIS)

    Kaushik, Priya Darshni; Ivanov, Ivan G.; Lin, Pin-Cheng; Kaur, Gurpreet; Eriksson, Jens; Lakshmi, G.B.V.S.; Avasthi, D.K.; Gupta, Vinay; Aziz, Anver; Siddiqui, Azher M.; Syväjärvi, Mikael; Yazdi, G. Reza

    2017-01-01

    Highlights: • For the first time the gas sensing application of SHI irradiated epitaxial graphene on SiC is explored. • Surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles. • Existence of an optimal fluence which maximize the gas sensing response towards NO_2 and NH_3 gases. - Abstract: In this work, surface functionalization of epitaxial graphene grown on silicon carbide was performed by ion irradiation to investigate their gas sensing capabilities. Swift heavy ion irradiation using 100 MeV silver ions at four varying fluences was implemented on epitaxial graphene to investigate morphological and structural changes and their effects on the gas sensing capabilities of graphene. Sensing devices are expected as one of the first electronic applications using graphene and most of them use functionalized surfaces to tailor a certain function. In our case, we have studied irradiation as a tool to achieve functionalization. Morphological and structural changes on epitaxial graphene layers were investigated by atomic force microscopy, Raman spectroscopy, Raman mapping and reflectance mapping. The surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles at highest fluence (2 × 10"1"3 ions/cm"2). Raman spectra analysis shows that the graphene defect density is increased with increasing fluence, while Raman mapping and reflectance mapping show that there is also a reduction of monolayer graphene coverage. The samples were investigated for ammonia and nitrogen dioxide gas sensing applications. Sensors fabricated on pristine and irradiated samples showed highest gas sensing response at an optimal fluence. Our work provides new pathways for introducing defects in controlled manner in epitaxial graphene, which can be used not only for gas sensing application but also for other applications, such as electrochemical, biosensing, magnetosensing and spintronic

  7. Surface functionalization of epitaxial graphene on SiC by ion irradiation for gas sensing application

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, Priya Darshni, E-mail: kaushik.priyadarshni@gmail.com [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Department of Physics, Jamia Millia Islamia, New Delhi, 110025 (India); Ivanov, Ivan G.; Lin, Pin-Cheng [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Kaur, Gurpreet [Department of Physics and Astrophysics, University of Delhi, Delhi, 110007 (India); Eriksson, Jens [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Lakshmi, G.B.V.S. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi, 110067 (India); Avasthi, D.K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi, 110067 (India); Amity Institute of Nanotechnology, Noida 201313 (India); Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi, 110007 (India); Aziz, Anver; Siddiqui, Azher M. [Department of Physics, Jamia Millia Islamia, New Delhi, 110025 (India); Syväjärvi, Mikael [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Yazdi, G. Reza, E-mail: yazdi@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden)

    2017-05-01

    Highlights: • For the first time the gas sensing application of SHI irradiated epitaxial graphene on SiC is explored. • Surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles. • Existence of an optimal fluence which maximize the gas sensing response towards NO{sub 2} and NH{sub 3} gases. - Abstract: In this work, surface functionalization of epitaxial graphene grown on silicon carbide was performed by ion irradiation to investigate their gas sensing capabilities. Swift heavy ion irradiation using 100 MeV silver ions at four varying fluences was implemented on epitaxial graphene to investigate morphological and structural changes and their effects on the gas sensing capabilities of graphene. Sensing devices are expected as one of the first electronic applications using graphene and most of them use functionalized surfaces to tailor a certain function. In our case, we have studied irradiation as a tool to achieve functionalization. Morphological and structural changes on epitaxial graphene layers were investigated by atomic force microscopy, Raman spectroscopy, Raman mapping and reflectance mapping. The surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles at highest fluence (2 × 10{sup 13} ions/cm{sup 2}). Raman spectra analysis shows that the graphene defect density is increased with increasing fluence, while Raman mapping and reflectance mapping show that there is also a reduction of monolayer graphene coverage. The samples were investigated for ammonia and nitrogen dioxide gas sensing applications. Sensors fabricated on pristine and irradiated samples showed highest gas sensing response at an optimal fluence. Our work provides new pathways for introducing defects in controlled manner in epitaxial graphene, which can be used not only for gas sensing application but also for other applications, such as electrochemical, biosensing, magnetosensing and

  8. Characteristics and mechanisms of hypothalamic neuronal fatty acid sensing.

    Science.gov (United States)

    Le Foll, Christelle; Irani, Boman G; Magnan, Christophe; Dunn-Meynell, Ambrose A; Levin, Barry E

    2009-09-01

    We assessed the mechanisms by which specialized hypothalamic ventromedial nucleus (VMN) neurons utilize both glucose and long-chain fatty acids as signaling molecules to alter their activity as a potential means of regulating energy homeostasis. Fura-2 calcium (Ca(2+)) and membrane potential dye imaging, together with pharmacological agents, were used to assess the mechanisms by which oleic acid (OA) alters the activity of dissociated VMN neurons from 3- to 4-wk-old rats. OA excited up to 43% and inhibited up to 29% of all VMN neurons independently of glucose concentrations. In those neurons excited by both 2.5 mM glucose and OA, OA had a concentration-dependent effective excitatory concentration (EC(50)) of 13.1 nM. Neurons inhibited by both 2.5 mM glucose and OA had an effective inhibitory concentration (IC(50)) of 93 nM. At 0.5 mM glucose, OA had markedly different effects on these same neurons. Inhibition of carnitine palmitoyltransferase, reactive oxygen species formation, long-chain acetyl-CoA synthetase and ATP-sensitive K(+) channel activity or activation of uncoupling protein 2 (UCP2) accounted for only approximately 20% of OA's excitatory effects and approximately 40% of its inhibitory effects. Inhibition of CD36, a fatty acid transporter that can alter cell function independently of intracellular fatty acid metabolism, reduced the effects of OA by up to 45%. Thus OA affects VMN neuronal activity through multiple pathways. In glucosensing neurons, its effects are glucose dependent. This glucose-OA interaction provides a potential mechanism whereby such "metabolic sensing" neurons can respond to differences in the metabolic states associated with fasting and feeding.

  9. Sensing of heavy metal ions by intrinsic TMV coat protein fluorescence

    Science.gov (United States)

    Bayram, Serene S.; Green, Philippe; Blum, Amy Szuchmacher

    2018-04-01

    We propose the use of a cysteine mutant of TMV coat protein as a signal transducer for the selective sensing and quantification of the heavy metal ions, Cd2+, Pb2+, Zn2+ and Ni2+ based on intrinsic tryptophan quenching. TMV coat protein is inexpensive, can be mass-produced since it is expressed and extracted from E-coli. It also displays several different functional groups, enabling a wide repertoire of bioconjugation chemistries; thus it can be easily integrated into functional devices. In addition, TMV-ion interactions have been widely reported and utilized for metallization to generate organic-inorganic hybrid composite novel materials. Building on these previous observations, we herein determine, for the first time, the TMV-ion binding constants assuming the static fluorescence quenching model. We also show that by comparing TMV-ion interactions between native and denatured coat protein, we can distinguish between chemically similar heavy metal ions such as cadmium and zinc ions.

  10. Modulation of the acidity of niobic acid by ion-doping: Effects of nature and amount of the dopant ions

    Energy Technology Data Exchange (ETDEWEB)

    Carniti, Paolo [Dipartimento di Chimica, Università degli Studi di Milano (UNIMI), Milano (Italy); Gervasini, Antonella, E-mail: antonella.gervasini@unimi.it [Dipartimento di Chimica, Università degli Studi di Milano (UNIMI), Milano (Italy); Marzo, Matteo [Dipartimento di Chimica, Università degli Studi di Milano (UNIMI), Milano (Italy); Auroux, Aline [Université Lyon 1, CNRS, UMR 5256, (IRCELYON), Villeurbanne (France)

    2013-09-10

    Highlights: ► Mitigation of the surface acidity of niobic acid was pursued by K-, Ba-, and Nd-doping. ► Thermal techniques of study were effective for the acidity study. ► The nature of the dopant influences the effectiveness of the acidity tuning of niobic acid. ► The acidity of the doped surfaces decreased with increasing the dopant species added to niobic acid. ► The samples showed different acidity when measured in gas–solid phase (intrinsic acidity) and water (effective acidity). - Abstract: The acidity of niobic acid (NBO) has been successfully mitigated and tuned by addition of K{sup +}, Ba{sup 2+} and Nd{sup 3+} dopant species in amounts from 1 to 15 atom nm{sup −2}. The characterization of the intrinsic acid properties of the samples was performed by adsorption of NH{sub 3} in a volumetric–microcalorimetric coupled line and by temperature programmed desorption (TPD) of 2-phenylethylamine in a thermogravimetric apparatus. The K-dopant was more effective in decreasing the acidity of niobic acid than the Ba- and Nd-dopants. Complementary measurements of the effective acidity of the samples in water by base titrations with 2-phenylethylamine completed the study and revealed a different picture of the effect of the three dopants on the NBO acidity in water. All the results indicated that the K-dopant targeted more selectively the Brønsted acid sites, acting as an ion-exchanger, while Ba- and Nd-species predominantly acted on the Lewis acid sites of the NBO surface.

  11. Atomistic Modeling of Ion Conduction through the Voltage-Sensing Domain of the Shaker K+ Ion Channel.

    Science.gov (United States)

    Wood, Mona L; Freites, J Alfredo; Tombola, Francesco; Tobias, Douglas J

    2017-04-20

    Voltage-sensing domains (VSDs) sense changes in the membrane electrostatic potential and, through conformational changes, regulate a specific function. The VSDs of wild-type voltage-dependent K + , Na + , and Ca 2+ channels do not conduct ions, but they can become ion-permeable through pathological mutations in the VSD. Relatively little is known about the underlying mechanisms of conduction through VSDs. The most detailed studies have been performed on Shaker K + channel variants in which ion conduction through the VSD is manifested in electrophysiology experiments as a voltage-dependent inward current, the so-called omega current, which appears when the VSDs are in their resting state conformation. Only monovalent cations appear to permeate the Shaker VSD via a pathway that is believed to be, at least in part, the same as that followed by the S4 basic side chains during voltage-dependent activation. We performed μs-time scale atomistic molecular dynamics simulations of a cation-conducting variant of the Shaker VSD under applied electric fields in an experimentally validated resting-state conformation, embedded in a lipid bilayer surrounded by solutions containing guanidinium chloride or potassium chloride. Our simulations provide insights into the Shaker VSD permeation pathway, the protein-ion interactions that control permeation kinetics, and the mechanism of voltage-dependent activation of voltage-gated ion channels.

  12. Ion-pair chromatography of nucleic acid derivatives

    International Nuclear Information System (INIS)

    Perrone, P.A.; Brown, P.R.

    1985-01-01

    Little work has been done on the ion-pair chromatography of nucleic acid constituents, although there is a great potential for the use of this technique in the field. Since the classic work in 1949, nucleotides, as well as nucleosides and bases, have been separated by ion-exchange chromatography. However, ion exchange is a difficult mode and most researchers prefer the use of reversed-phase whenever possible. Although reversed-phase is now the method of choice, ionic compounds like nucleotides and some of the more polar bases are not adequately retained by many systems of this type. In addition, it is difficult to analyze simultaneously members of all three classes of nucleic acid compounds (bases, nucleosides, and nucleotides) using a reversed-phase system, even with gradient elution. Ion pairing can be a useful technique because, theoretically, the separation of nonionic bases and nucleosides along with the ionic nucleotides can be achieved. Additionally, each group of compounds may be separated isocratically. In this chapter, they will discuss ion-pair chromatography as applied to nucleic acid constituents. The current theories, advantages and disadvantages, a limited number of applications, and potential for future work are presented

  13. Luminescence enhancement of uranyl ion by benzoic acid in acetonitrile

    International Nuclear Information System (INIS)

    Satendra Kumar; Maji, S.; Joseph, M.; Sankaran, K.

    2014-01-01

    Uranyl ion is known for its characteristic green luminescence and therefore luminescence spectroscopy is a suitable technique for characterizing different uranyl species. In aqueous medium, luminescence of uranyl ion is generally weak due to its quenching by water molecules and therefore in order to enhance the luminescence of uranyl ion in aqueous medium, luminescence enhancing reagents such as H 3 PO 4 , H 2 SO 4 , HCIO 4 have been widely used. The other method to enhance the uranyl luminescence is by ligand sensitized luminescence, a method well established for lanthanides. In this work, luminescence of uranyl ion is found to be enhanced by benzoic acid in acetonitrile medium. In aqueous medium benzoic acid does not enhance the uranyl luminescence although it forms 1:1 and 1:2 complexes with uranyl ion. Luminescence spectra of uranyl benzoate revealed that enhancement is due to sensitization of uranyl luminescence by benzoate ions. UV-Vis spectroscopy has been utilized to characterize the specie formed in the in acetonitrile medium. UV-Vis spectroscopy along with luminescence spectra revealed that the specie to be tribenzoate complex of uranyl (UO 2 (C 6 H 5 COO) 3 ) - having D 3 h symmetry. (author)

  14. Kinetic study of ion exchange in phosphoric acid chelating resin

    International Nuclear Information System (INIS)

    Brikci-Nigassa, Mounir; Hamouche, Hafida

    1995-11-01

    Uranium may be recovered as a by product of wet phosphoric acid using a method based on specific ion exchange resins. These resins called chelates contain amino-phosphonic functional groups. The resin studied in this work is a purolite S-940; uranium may be loaded on this resin from 30% P2O5 phosphoric acid in its reduced state. The influence of different parameters on the successive steps of the process have been studied in batch experiments: uranium reduction, loading and oxydation. Uranium may be eluted with ammonium carbonate and the resin regeneration may be done with hydrochloric acid.Ferric ions reduce the effective resin capacity considerably and inert fixation conditions are proposed to enhance uranium loading

  15. Ion-step method for surface potential sensing of silicon nanowires

    NARCIS (Netherlands)

    Chen, S.; van Nieuwkasteele, Jan William; van den Berg, Albert; Eijkel, Jan C.T.

    2016-01-01

    This paper presents a novel stimulus-response method for surface potential sensing of silicon nanowire (Si NW) field-effect transistors. When an "ion-step" from low to high ionic strength is given as a stimulus to the gate oxide surface, an increase of double layer capacitance is therefore expected.

  16. A novel start algorithm for CNG engines using ion sense technology

    NARCIS (Netherlands)

    Bie, T. de; Ericsson, M.; Rask, P.

    2000-01-01

    This paper presents a start algorithm that is able to control the air/fuel ratio (AFR) during the cranking phase and immediately hereafter, where the ordinary ?-control is not yet enabled. The control is based on the ion sense principle, which means that a current through the spark plug is measured

  17. Kv7.1 ion channels require a lipid to couple voltage sensing to pore opening.

    Science.gov (United States)

    Zaydman, Mark A; Silva, Jonathan R; Delaloye, Kelli; Li, Yang; Liang, Hongwu; Larsson, H Peter; Shi, Jingyi; Cui, Jianmin

    2013-08-06

    Voltage-gated ion channels generate dynamic ionic currents that are vital to the physiological functions of many tissues. These proteins contain separate voltage-sensing domains, which detect changes in transmembrane voltage, and pore domains, which conduct ions. Coupling of voltage sensing and pore opening is critical to the channel function and has been modeled as a protein-protein interaction between the two domains. Here, we show that coupling in Kv7.1 channels requires the lipid phosphatidylinositol 4,5-bisphosphate (PIP2). We found that voltage-sensing domain activation failed to open the pore in the absence of PIP2. This result is due to loss of coupling because PIP2 was also required for pore opening to affect voltage-sensing domain activation. We identified a critical site for PIP2-dependent coupling at the interface between the voltage-sensing domain and the pore domain. This site is actually a conserved lipid-binding site among different K(+) channels, suggesting that lipids play an important role in coupling in many ion channels.

  18. Bio-functionalized silver nanoparticles for selective colorimetric sensing of toxic metal ions and antimicrobial studies

    Science.gov (United States)

    Vinod Kumar, V.; Anbarasan, S.; Christena, Lawrence Rene; SaiSubramanian, Nagarajan; Philip Anthony, Savarimuthu

    2014-08-01

    Hibiscus Sabdariffa (Gongura) plant extracts (leaves (HL) and stem (HS) were used for the first time in the green synthesis of bio-functionalized silver nanoparticles (AgNPs). The bio-functionality of AgNPs has been successfully utilized for selective colorimetric sensing of potentially health and environmentally hazardous Hg2+, Cd2+ and Pb2+ metal ions at ppm level in aqueous solution. Importantly, clearly distinguishable colour for all three metal ions was observed. The influence of extract preparation condition and pH were also explored on the formation of AgNPs. Both selectivity and sensitivity differed for AgNPs synthesized from different parts of the plant. Direct correlation between the stability of green synthesized AgNPs at different pH and its antibacterial effects has been established. The selective colorimetric sensing of toxic metal ions and antimicrobial effect of green synthesized AgNPs demonstrated the multifunctional applications of green nanotechnology.

  19. Characteristics of a continuous denitration by formic acid - electrolytic trimming of residual acid with accompanying the precipitation of metal ions

    International Nuclear Information System (INIS)

    Kim, G. W.; Kim, S. H.; Lim, J. G.; Lee, I. H.

    2003-01-01

    This work has studied the characteristics of destruction of nitric acid and precipitation of several metal ions in a continuous denitration process combining a denitration by formic acid and a residual acid-electrolytic trimming system. The metal ions of Zr, Mo, Fe, and Nd did not affect the electrodes at the step of electrolytic trimming of the residual acid after denitration by formic acid. The Mo ion in electrolytic solution enhanced the generation of nitrite ion during the electrolytic reaction. The mole ratio of formic acid to nitric acid fed into the continuous denitration reactor using formic acid affected much the final acidity, the precipitation yields of metal ions, the precipitate morphology. At the ratio of 1.65, the process had the lowest final acidity of less than 0.1 M, and the precipitation yields of Zr and Mo reached 95% and 83%, respectively as the highest values

  20. Fabrication, characterization and sensing properties of Cu(II) ion imprinted sol–gel thin film on QCM

    International Nuclear Information System (INIS)

    Su, Pi-Guey; Hung, Fang-Chieh; Lin, Po-Hung

    2012-01-01

    Cu(II)-molecularly imprinted sol–gel films (Cu(II)-MISGF), coated on a quartz crystal microbalance (QCM) chip, were fabricated using a sol–gel procedure. Co-hydrolysis and co-condensation of Cu(II) (templates), 3-aminopropyltrimethoxysilane (APTS, functional monomer) and tetraethoxysilane (TEOS, cross-linking agent) were performed with acid and base catalysis. The properties of the Cu(II)-MISGF were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and the electrochemical methods of cyclic voltammetry (CV). Microstructural observations revealed that the acid-catalyzed system yielded more mechanically stable thin films. A combined Cu(II)-MISGF-QCM with flow injection analysis (FIA) method was utilized to investigate the sensing performance of the Cu(II)-MISGF, with special emphasis on the most important properties of sensitivity, selectivity and response time. The Cu(II)-MISGF-QCM sensor, at a TEOS/APTS molar ratio of 10, exhibited excellent selectivity and rapidly responded to Cu(II) ions. - Highlights: ► A Cu(II)-molecularly imprinted sol–gel thin film on chip was fabricated. ► The thin film had mechanical stability using acidic catalyst. ► The thin film had good selectivity and response time for Cu(II) ions.

  1. Extraction of europium (3) ions with stearic acid

    International Nuclear Information System (INIS)

    Lobanov, F.I.; Gladyshchev, V.P.; Nurtaeva, A.K.; Andreeva, N.N.

    1981-01-01

    Extraction of europium (3) in nitric acid solutions with the melts of stearic acid and its mixtures with paraffin at (80+-1) deg C is studied. The constant of stearic acid dimerization in paraffin K 2 =9.6+-0.6 and the constant of stearic acid distribution in the paraffin-water system Ksub(D,HA)=(1.06+-0.07)x10sub(3) are determined. The diagram of europium ion extraction at initial concentrations of metal in the aqueous phase of 10 -4 -10 -3 mol/l is suggested. The compound extracted has the EuA 3 composition with extraction constant of lg Ksub(ex)=-7.58 [ru

  2. Fragmentation of acetic acid ions with selected internal energies

    Science.gov (United States)

    Zha, Qingmei; Nishimura, Toshihide; Bertrand, Michel J.; Meisels, G. G.

    1991-08-01

    The unimolecular dissociation of acetic acid ion in the photon energy range 10.5-17.0 eV was studied using threshold photoelectron photoion coincidence mass spectrometry. The detailed breakdown graph was obtained and the fragmentation pathways were elucidated. The breakdown graph calculated using statistical theories was found to be consistent with the experimental data up to a photon energy of about 12.5 eV. The average kinetic energy release observed is higher than that calculated on the basis of quasi-equilibrium theory for the formation of COOH+ while it seems to be statistical for the formation of CH3CO+. The origin of kinetic energy release accompanying the formation of these two ions is discussed. The structure of [COH3]+ ion (m/z 31) is determined to be hydroxymethyl cation, CH2OH+, which could be formed by a two-step rearrangement prior to dissociation.

  3. Reactivity of the cadmium ion in concentrated phosphoric acid solutions.

    Science.gov (United States)

    De Gyves, J; Gonzales, J; Louis, C; Bessiere, J

    1989-07-01

    The solvation transfer coefficients which characterize the changes of ion reactivity with phosphoric acid concentration have been calculated for cadmium from the constants of the successive chloride complexes, and for silver and diethyldithiophosphate from potentiometric measurements. They evidence the strong desolvation of the cadmium species in concentrated phosphoric acid media, causing a remarkable increase of its reactivity. They allow the results of liquid-liquid extraction, precipitation and flotation reactions to be correctly interpreted and their changes to be foreseen when the reagents are modified.

  4. The role of ammonia in sulfuric acid ion induced nucleation

    Directory of Open Access Journals (Sweden)

    I. K. Ortega

    2008-06-01

    Full Text Available We have developed a new multi-step strategy for quantum chemical calculations on atmospherically relevant cluster structures that makes calculation for large clusters affordable with a good accuracy-to-computational effort ratio. We have applied this strategy to evaluate the relevance of ternary ion induced nucleation; we have also performed calculations for neutral ternary nucleation for comparison. The results for neutral ternary nucleation agree with previous results, and confirm the important role of ammonia in enhancing the growth of sulfuric acid clusters. On the other hand, we have found that ammonia does not enhance the growth of ionic sulfuric acid clusters. The results also confirm that ion-induced nucleation is a barrierless process at high altitudes, but at ground level there exists a barrier due to the presence of a local minimum on the free energy surface.

  5. Visual and sensitive fluorescent sensing for ultratrace mercury ions by perovskite quantum dots.

    Science.gov (United States)

    Lu, Li-Qiang; Tan, Tian; Tian, Xi-Ke; Li, Yong; Deng, Pan

    2017-09-15

    Mercury ions sensing is an important issue for human health and environmental safety. A novel fluorescence nanosensor was designed for rapid visual detection of ultratrace mercury ions (Hg 2+ ) by using CH 3 NH 3 PbBr 3 perovskite quantum dots (QDs) based on the surface ion-exchange mechanism. The synthesized CH 3 NH 3 PbBr 3 QDs can emitt intense green fluorescence with high quantum yield of 50.28%, and can be applied for Hg 2+ sensing with the detection limit of 0.124 nM (24.87 ppt) in the range of 0 nM-100 nM. Furthermore, the interfering metal ions have no any influence on the fluorescence intensity of QDs, showing the perovskite QDs possess the high selectivity and sensitivity for Hg 2+ detection. The sensing mechanism of perovskite QDs for Hg 2+ is has also been investigated by XPS, EDX studies, showing Pb 2+ on the surface of perovskite QDs has been partially replaced by Hg 2+ . Spot plate test shows that the perovskite QDs can also be used for visual detection of Hg 2+ . Our research indicated the perovskite QDs are promising candidates for the visual fluorescence detection of environmental micropollutants. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Gadolinium(III) ion selective sensor using a new synthesized Schiff's base as a sensing material

    International Nuclear Information System (INIS)

    Zamani, Hassan Ali; Mohammadhosseini, Majid; Haji-Mohammadrezazadeh, Saeed; Faridbod, Farnoush; Ganjali, Mohammad Reza; Meghdadi, Soraia; Davoodnia, Abolghasem

    2012-01-01

    According to a solution study which showed a selective complexation between N,N′-bis(methylsalicylidene)-2-aminobenzylamine (MSAB) and gadolinium ions, MSAB was used as a sensing element in construction of a gadolinium(III) ion selective electrode. Acetophenon (AP) was used as solvent mediator and sodium tetraphenyl borate (NaTPB) as an anion excluder. The electrode showed a good selectivity towards Gd(III) ions over a wide variety of cations tested. The constructed sensor displayed a Nernstian behavior (19.7 ± 0.3 mV/decade) in the concentration range of 1.0 × 10 −6 to 1.0 × 10 −2 mol L −1 with detection limit of 5.0 × 10 −7 mol L −1 and a short response time ( 3+ –PVC membrane sensor based on an ion carrier as sensing material is introduced. ► This technique is very simple and it's not necessary to use sophisticated equipment. ► This sensor shows good selectivity against other metal ions.

  7. Monolayer-functionalized microfluidics devices for optical sensing of acidity

    NARCIS (Netherlands)

    Mela, P.; Onclin, S.; Goedbloed, M.H.; Levi, S.; Garcia Parajo, M.F.; van Hulst, N.F.; Ravoo, B.J.; Reinhoudt, David; van den Berg, Albert

    This paper describes the integration of opto-chemosensors in microfluidics networks. Our technique exploits the internal surface of the network as a platform to build a sensing system by coating the surface with a self-assembled monolayer and subsequently binding a fluorescent sensing molecule to

  8. Mutations in the voltage-sensing domain affect the alternative ion permeation pathway in the TRPM3 channel.

    Science.gov (United States)

    Held, Katharina; Gruss, Fabian; Aloi, Vincenzo Davide; Janssens, Annelies; Ulens, Chris; Voets, Thomas; Vriens, Joris

    2018-03-31

    Mutagenesis at positively charged amino acids (arginines and lysines) (R1-R4) in the voltage-sensor domain (transmembrane segment (S) 4) of voltage-gated Na + , K + and Ca 2+ channels can lead to an alternative ion permeation pathway distinct from the central pore. Recently, a non-canonical ion permeation pathway was described in TRPM3, a member of the transient receptor potential (TRP) superfamily. The non-canonical pore exists in the native TRPM3 channel and can be activated by co-stimulation of the endogenous agonist pregnenolone sulphate and the antifungal drug clotrimazole or by stimulation of the synthetic agonist CIM0216. Alignment of the voltage sensor of Shaker K + channels with the entire TRPM3 sequence revealed the highest degree of similarity in the putative S4 region of TRPM3, and suggested that only one single gating charge arginine (R2) in the putative S4 region is conserved. Mutagenesis studies in the voltage-sensing domain of TRPM3 revealed several residues in the voltage sensor (S4) as well as in S1 and S3 that are crucial for the occurrence of the non-canonical inward currents. In conclusion, this study provides evidence for the involvement of the voltage-sensing domain of TRPM3 in the formation of an alternative ion permeation pathway. Transient receptor potential (TRP) channels are cationic channels involved in a broad array of functions, including homeostasis, motility and sensory functions. TRP channel subunits consist of six transmembrane segments (S1-S6), and form tetrameric channels with a central pore formed by the region encompassing S5 and S6. Recently, evidence was provided for the existence of an alternative ion permeation pathway in TRPM3, which allows large inward currents upon hyperpolarization independently of the central pore. However, very little knowledge is available concerning the localization of this alternative pathway in the native TRPM3 channel protein. Guided by sequence homology with Shaker K + channels, in which

  9. Dissipative quantum error correction and application to quantum sensing with trapped ions.

    Science.gov (United States)

    Reiter, F; Sørensen, A S; Zoller, P; Muschik, C A

    2017-11-28

    Quantum-enhanced measurements hold the promise to improve high-precision sensing ranging from the definition of time standards to the determination of fundamental constants of nature. However, quantum sensors lose their sensitivity in the presence of noise. To protect them, the use of quantum error-correcting codes has been proposed. Trapped ions are an excellent technological platform for both quantum sensing and quantum error correction. Here we present a quantum error correction scheme that harnesses dissipation to stabilize a trapped-ion qubit. In our approach, always-on couplings to an engineered environment protect the qubit against spin-flips or phase-flips. Our dissipative error correction scheme operates in a continuous manner without the need to perform measurements or feedback operations. We show that the resulting enhanced coherence time translates into a significantly enhanced precision for quantum measurements. Our work constitutes a stepping stone towards the paradigm of self-correcting quantum information processing.

  10. Proof-of-concept study of a marine ion-selective optical sensing instrument

    Science.gov (United States)

    Sobron, P.; Thompson, C.; Bamsey, M.

    2013-12-01

    We have developed a proof-of-concept instrument for real-time in-situ characterization of the ion chemistry of the ocean. Our instrument uses optical sensors equipped with ion-selective membranes which exhibit a change in an optical property that can be correlated with the concentration of a specific ion. We have implemented a system for multi-ion sensing that includes the use of a single spectrometer in tandem with a fiber optic multiplexer that is capable of reading a suite of attached optrodes, each of them dedicated to a unique ion. In this abstract we report the experimental characterization of calcium and potassium optrodes as a template for ion-selective optrodes and their application to the characterization of the oceans. The tests were performed at the Controlled Environment Systems Research Facility of the University of Guelph. Guelph's optrode housing was tested by immersing it in a 1/2 strength Hoagland's hydroponic solution to test functionality of the K+ and Ca2+ optrodes in this environment. Our results demonstrate the feasibility of recording spectral information in sub-minute times from more than one optrode simultaneously in a given aqueous system. This proof-of-concept study has allowed us to measure parameters of interest and comparison to analytical predictions for critical subsystems of a deployable system, and demonstrates maturity of the multi-ion sensing optrode technology. Critical advantages of our optrode system are that it: (1) enables concurrent measurements of multiple ionic species relevant in ocean sciences; (2) has high time and spatial resolution; (3) has low limits of detection; (4) uses low-cost, low-mass, energy efficient optoelectronics. Our system has the potential for facilitating new observational, experimental, and analytic capabilities in ocean sciences, including: (a) health and environment monitoring; (b) aquaculture; (c) global change, e.g. ocean acidification; and (d) origin of life research. Proof-of-concept setup at

  11. Strong activation of bile acid-sensitive ion channel (BASIC) by ursodeoxycholic acid

    Science.gov (United States)

    Wiemuth, Dominik; Sahin, Hacer; Lefèvre, Cathérine M.T.; Wasmuth, Hermann E.; Gründer, Stefan

    2013-01-01

    Bile acid-sensitive ion channel (BASIC) is a member of the DEG/ENaC gene family of unknown function. Rat BASIC (rBASIC) is inactive at rest. We have recently shown that cholangiocytes, the epithelial cells lining the bile ducts, are the main site of BASIC expression in the liver and identified bile acids, in particular hyo- and chenodeoxycholic acid, as agonists of rBASIC. Moreover, it seems that extracellular divalent cations stabilize the resting state of rBASIC, because removal of extracellular divalent cations opens the channel. In this addendum, we demonstrate that removal of extracellular divalent cations potentiates the activation of rBASIC by bile acids, suggesting an allosteric mechanism. Furthermore, we show that rBASIC is strongly activated by the anticholestatic bile acid ursodeoxycholic acid (UDCA), suggesting that BASIC might mediate part of the therapeutic effects of UDCA. PMID:23064163

  12. Application of monocarboxylic acids for the extraction of metal ions-literature survey

    International Nuclear Information System (INIS)

    Brzozka, Z.; Rozycki, C.

    1980-01-01

    In the paper there is presented a literature review concerning the application of monocarboxylic acids for extraction of metal ions. The following problems are discussed: characteristic of monocarboxylic acids and their mixtures, the equilibria between the acid solution in organic solvent and aqueous phase, the mechanism of acid partition, complexes of carboxylic acids and metal ions in aqueous phase, mechanism of extraction by means of carboxylic acids as well as the problems concerning the extraction of individual metal ions. Data about the extraction of metal ions are presented in table. The 138 references are given. (author)

  13. Template-directed synthesis of oligoguanylic acids - Metal ion catalysis

    Science.gov (United States)

    Bridson, P. K.; Fakhrai, H.; Lohrmann, R.; Orgel, L. E.; Van Roode, M.

    1981-01-01

    The effects of Zn(2+), Pb(2+) and other metal ions on the efficiency and stereo-selectivity of the template-directed oligomerization of guanosine 5'-phosphorimidazolide are investigated. Reactions were run in the presence of a polyC template in a 2,6-lutidine buffer, and products analyzed by high-performance liquid chromatography on an RPC-5 column. The presence of the Pb(2+) ion is found to lead to the formation of 2'-5' linked oligomers up to the 40-mer, while Zn(2+) favors the formation of predominantly 3'-5' linked oligomers up to the 35-mer. When amounts of uracil, cytidine or adenosine 5'-phosphorimidazole equal to those of the guanosine derivative are included in the reaction mixture, the incorrect base is incorporated into the oligomer about 10% of the time with a Pb(2+) catalyst, but less than 0.5% of the time with Zn(2+). The Sn(2+), Sb(3+) and Bi(3+) ions are also found to promote the formation of 2'-5' oligomers, although not as effectively as Pb(2+), while no metal ions other than Zn(2+) promote the formation of the 3'-5' oligomers. The results may be important for the understanding of the evolution of nucleic acid replication in the absence of enzymes.

  14. Biomimetic supercontainers for size-selective electrochemical sensing of molecular ions

    Science.gov (United States)

    Netzer, Nathan L.; Must, Indrek; Qiao, Yupu; Zhang, Shi-Li; Wang, Zhenqiang; Zhang, Zhen

    2017-04-01

    New ionophores are essential for advancing the art of selective ion sensing. Metal-organic supercontainers (MOSCs), a new family of biomimetic coordination capsules designed using sulfonylcalix[4]arenes as container precursors, are known for their tunable molecular recognition capabilities towards an array of guests. Herein, we demonstrate the use of MOSCs as a new class of size-selective ionophores dedicated to electrochemical sensing of molecular ions. Specifically, a MOSC molecule with its cavities matching the size of methylene blue (MB+), a versatile organic molecule used for bio-recognition, was incorporated into a polymeric mixed-matrix membrane and used as an ion-selective electrode. This MOSC-incorporated electrode showed a near-Nernstian potentiometric response to MB+ in the nano- to micro-molar range. The exceptional size-selectivity was also evident through contrast studies. To demonstrate the practical utility of our approach, a simulated wastewater experiment was conducted using water from the Fyris River (Sweden). It not only showed a near-Nernstian response to MB+ but also revealed a possible method for potentiometric titration of the redox indicator. Our study thus represents a new paradigm for the rational design of ionophores that can rapidly and precisely monitor molecular ions relevant to environmental, biomedical, and other related areas.

  15. Acridine-based fluorescence chemosensors for selective sensing of Fe3+ and Ni2+ ions

    Science.gov (United States)

    Wang, Chaoyu; Fu, Jiaxin; Yao, Kun; Xue, Kun; Xu, Kuoxi; Pang, Xiaobin

    2018-06-01

    Two novel acridine-based fluorescence chemosensors (L1 and L2) were prepared and their metal ions sensing properties were investigated. L1 (L2) exhibited an excellent selective fluorescence response toward Fe3+ (Ni2+) and the stoichiometry ratio of L1-Fe3+ and L2-Ni2+ were 1:1. The detection limits of L1 and L2 were calculated by the fluorescence titration to be 4.13 μM and 1.52 μM, respectively, which were below the maximum permissive level of Fe3+ and Ni2+ ions in drinking water set by the EPA. The possible mechanism of the fluorescence detection of Fe3+ and Ni2+ had been proposed according to the analysis of Job's plot, IR spectra and ESI-MS. The determination of Fe3+ and Ni2+ ions in living cells had been applied successfully.

  16. Electropolymerized Molecularly Imprinted Polypyrrole Film for Sensing of Clofibric Acid

    OpenAIRE

    Schweiger, Bianca; Kim, Jungtae; Kim, Young; Ulbricht, Mathias

    2015-01-01

    Piezoelectric quartz crystals and analogous gold substrates were electrochemically coated with molecularly imprinted polypyrrole films for pulsed amperometric detection (PAD) of clofibric acid, a metabolite of clofibrate. Cyclic voltammetry data obtained during polymerization and deposited weight estimations revealed a decrease of the polymerization rate with increasing clofibric acid concentration. XPS measurements indicated that clofibric acid could be removed after imprinting with an aqueo...

  17. Polyethyleneimine-templated copper nanoclusters via ascorbic acid reduction approach as ferric ion sensor

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jie; Ju, Yuyun; Liu, Juanjuan; Zhang, Huige [State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Chen, Xingguo, E-mail: chenxg@lzu.edu.cn [State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou 730000 (China)

    2015-01-07

    Highlights: • A new method for synthesis of the BPEI-CuNCs is established. • A facile approach for Fe{sup 3+} ion sensing by fluorescence quenching is developed. • The method for Fe{sup 3+} sensing has high sensitivity and excellent selectivity. - Abstract: In this report we reported a facile one-pot method for synthesis of water-soluble and stable fluorescent CuNCs at room temperature, in which branched polyethyleneimine (BPEI) served as capping scaffold and ascorbic acid as reducing agent. The prepared BPEI-CuNCs exhibited excellent properties such as good water-solubility, photostability and high stability toward high ionic strength. Based on the electron transfer induced fluorescence quenching mechanism, this fluorescence probe was used for the sensitive and selective determination of ferric ions (Fe{sup 3+}) in aqueous solution. The limit of detection was 340 nM in the linear range of 0.5–1000 μM, which was lower than the maximum level of Fe{sup 3+} permitted in drinking water by the U.S. Environmental Protection Agency. The method was successfully applied to the detection of Fe{sup 3+} in tap water, Yellow River water and human urine samples with the quantitative spike recoveries ranging from 95.3% to 112.0%.

  18. Polyethyleneimine-templated copper nanoclusters via ascorbic acid reduction approach as ferric ion sensor

    International Nuclear Information System (INIS)

    Feng, Jie; Ju, Yuyun; Liu, Juanjuan; Zhang, Huige; Chen, Xingguo

    2015-01-01

    Highlights: • A new method for synthesis of the BPEI-CuNCs is established. • A facile approach for Fe 3+ ion sensing by fluorescence quenching is developed. • The method for Fe 3+ sensing has high sensitivity and excellent selectivity. - Abstract: In this report we reported a facile one-pot method for synthesis of water-soluble and stable fluorescent CuNCs at room temperature, in which branched polyethyleneimine (BPEI) served as capping scaffold and ascorbic acid as reducing agent. The prepared BPEI-CuNCs exhibited excellent properties such as good water-solubility, photostability and high stability toward high ionic strength. Based on the electron transfer induced fluorescence quenching mechanism, this fluorescence probe was used for the sensitive and selective determination of ferric ions (Fe 3+ ) in aqueous solution. The limit of detection was 340 nM in the linear range of 0.5–1000 μM, which was lower than the maximum level of Fe 3+ permitted in drinking water by the U.S. Environmental Protection Agency. The method was successfully applied to the detection of Fe 3+ in tap water, Yellow River water and human urine samples with the quantitative spike recoveries ranging from 95.3% to 112.0%

  19. Oxidative decarboxylation of glycolic and phenylacetic acids with cerium(4) catalyzed by silver ions in the sulfuric acid media

    International Nuclear Information System (INIS)

    Venkatesvar Rao, G.; Nagardzhun Rao, Ch.; Sajprakash, P.K.

    1981-01-01

    Oxidative decarboxylation of glycolic and phenylacetic acids by cerium (4) in the presence of Ag + ions is studied. The Ce(4) order equals 1, glycolic acid order in the absence of a catalyst also equals 1 and is fractional (0.5) for a catalytic reaction. The phenylacetic acid order is fractional (0.75). The Ag + ion reaction order is fractional and constitutes 0.32 for glycolic and 0.36 for phenylacetic acids. The reaction mechanism is proposed [ru

  20. A review on various electrochemical techniques for heavy metal ions detection with different sensing platforms.

    Science.gov (United States)

    Bansod, BabanKumar; Kumar, Tejinder; Thakur, Ritula; Rana, Shakshi; Singh, Inderbir

    2017-08-15

    Heavy metal ions are non-biodegradable and contaminate most of the natural resources occurring in the environment including water. Some of the heavy metals including Lead (Pb), Mercury (Hg), Arsenic (As), Chromium (Cr) and Cadmium (Cd) are considered to be highly toxic and hazardous to human health even at trace levels. This leads to the requirement of fast, accurate and reliable techniques for the detection of heavy metal ions. This review presents various electrochemical detection techniques for heavy metal ions those are user friendly, low cost, provides on-site and real time monitoring as compared to other spectroscopic and optical techniques. The categorization of different electrochemical techniques is done on the basis of different types of detection signals generated due to presence of heavy metal ions in the solution matrix like current, potential, conductivity, electrochemical impedance, and electrochemiluminescence. Also, the recent trends in electrochemical detection of heavy metal ions with various types of sensing platforms including metals, metal films, metal oxides, nanomaterials, carbon nano tubes, polymers, microspheres and biomaterials have been evoked. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Surface plasmon resonance sensing detection of mercury and lead ions based on conducting polymer composite.

    Directory of Open Access Journals (Sweden)

    Mahnaz M Abdi

    Full Text Available A new sensing area for a sensor based on surface plasmon resonance (SPR was fabricated to detect trace amounts of mercury and lead ions. The gold surface used for SPR measurements were modified with polypyrrole-chitosan (PPy-CHI conducting polymer composite. The polymer layer was deposited on the gold surface by electrodeposition. This optical sensor was used for monitoring toxic metal ions with and without sensitivity enhancement by chitosan in water samples. The higher amounts of resonance angle unit (ΔRU were obtained for PPy-CHI film due to a specific binding of chitosan with Pb(2+ and Hg(2+ ions. The Pb(2+ ion bind to the polymer films most strongly, and the sensor was more sensitive to Pb(2+ compared to Hg(2+. The concentrations of ions in the parts per million range produced the changes in the SPR angle minimum in the region of 0.03 to 0.07. Data analysis was done by Matlab software using Fresnel formula for multilayer system.

  2. Recyclable fluorescent gold nanocluster membrane for visual sensing of copper(II) ion in aqueous solution.

    Science.gov (United States)

    Lin, Zhijin; Luo, Fenqiang; Dong, Tongqing; Zheng, Liyan; Wang, Yaxian; Chi, Yuwu; Chen, Guonan

    2012-05-21

    Recently, metal-selective fluorescent chemosensors have attracted intense attention for their simple and real-time tracking of metal ions in environmental samples. However, most of the existing fluorescent sensors are one-off sensors and thus suffer from large amount of reagent consumption, significant experimental cost and raising the risk of environmental pollution. In this paper, we developed a green (low reagent consumption, low-toxicity reagent use), recyclable, and visual sensor for Cu(2+) in aqueous solution by using a fluorescent gold nanoclusters membrane (FGM) as the sensing unit, basing on our findings on gold nanoclusters (Au NCs) that the bovine serum albumin (BSA)-coated Au NCs exhibit excellent membrane-forming ability under the isoelectric point of BSA, and thus enable us to obtain a new type of sensing membrane (i.e. FGM) by denaturing Au NCs; the fluorescence of FGM can be significantly quenched by Cu(2+) ion, and the quenched fluorescence can be totally recovered by histidine; the as-prepared FGM is very stable and recyclable, which makes it an ideal sensing material.

  3. Electropolymerized molecularly imprinted polypyrrole film for sensing of clofibric acid.

    Science.gov (United States)

    Schweiger, Bianca; Kim, Jungtae; Kim, Young Jun; Ulbricht, Mathias

    2015-02-26

    Piezoelectric quartz crystals and analogous gold substrates were electrochemically coated with molecularly imprinted polypyrrole films for pulsed amperometric detection (PAD) of clofibric acid, a metabolite of clofibrate. Cyclic voltammetry data obtained during polymerization and deposited weight estimations revealed a decrease of the polymerization rate with increasing clofibric acid concentration. XPS measurements indicated that clofibric acid could be removed after imprinting with an aqueous ethanol solution, which was further optimized by using PAD. Zeta potential and contact angle measurements revealed differences between molecularly imprinted (MIP) and non-imprinted polymer (NIP) layers. Binding experiments with clofibric acid and other substances showed a pronounced selectivity of the MIP for clofibric acid vs. carbamazepine, but the response of MIP and NIP to 2,4-dichlorophenoxyacetic acid was higher than that for clofibric acid. A smooth surface, revealed by AFM measurements, with roughness of 6-8 nm for imprinted and non-imprinted layers, might be a reason for an excessively low density of specific binding sites for clofibric acid. Furthermore, the decreased polymerization rate in the presence of clofibric acid might not result in well-defined polymer structures, which could be the reason for the lower sensitivity.

  4. Electropolymerized Molecularly Imprinted Polypyrrole Film for Sensing of Clofibric Acid

    Directory of Open Access Journals (Sweden)

    Bianca Schweiger

    2015-02-01

    Full Text Available Piezoelectric quartz crystals and analogous gold substrates were electrochemically coated with molecularly imprinted polypyrrole films for pulsed amperometric detection (PAD of clofibric acid, a metabolite of clofibrate. Cyclic voltammetry data obtained during polymerization and deposited weight estimations revealed a decrease of the polymerization rate with increasing clofibric acid concentration. XPS measurements indicated that clofibric acid could be removed after imprinting with an aqueous ethanol solution, which was further optimized by using PAD. Zeta potential and contact angle measurements revealed differences between molecularly imprinted (MIP and non-imprinted polymer (NIP layers. Binding experiments with clofibric acid and other substances showed a pronounced selectivity of the MIP for clofibric acid vs. carbamazepine, but the response of MIP and NIP to 2,4-dichlorophenoxyacetic acid was higher than that for clofibric acid. A smooth surface, revealed by AFM measurements, with roughness of 6–8 nm for imprinted and non-imprinted layers, might be a reason for an excessively low density of specific binding sites for clofibric acid. Furthermore, the decreased polymerization rate in the presence of clofibric acid might not result in well-defined polymer structures, which could be the reason for the lower sensitivity.

  5. Calcium ion binding to a soil fulvic acid using a Donnan Potential model

    International Nuclear Information System (INIS)

    Marinsky, J.A.

    1999-01-01

    Calcium ion binding to a soil fulvic acid (Armadale Bh Horizon) was evaluated over a range of calcium ion concentrations, from pH 3.8 to 7.3, using potentiometric titrations and calcium ion electrode measurements. Fulvic acid concentration was constant (100 milligrams per liter) and calcium ion concentration varied up to 8 x 10 -4 moles per liter. Experiments discussed here included: (1) titrations of fulvic acid-calcium ion containing solutions with sodium hydroxide; and (2) titrations of fully neutralized fulvic acid with calcium chloride solutions. Apparent binding constants (expressed as the logarithm of the value, log β app ) vary with solution pH, calcium ion concentration, degree of acid dissociation, and ionic strength (from log β app =2.5 to 3.9) and are similar to those reported by others. Fulvic acid charge, and the associated Donnan Potential, influences calcium ion-fulvic acid ion pair formation. A Donnan Potential correction term allowed calculation of intrinsic calcium ion-fulvic acid binding constants. Intrinsic binding constants vary from 1.2 to 2.5 (the average value is about log β=1.6) and are similar to, but somewhat higher than, stability constants for calcium ion-carboxylic acid monodentate complexes. (orig.)

  6. Complexation and extraction of series 4f, 5f and 4d ions by dialkyldithiophosphoric acids

    International Nuclear Information System (INIS)

    Fitoussi, Richard.

    1982-04-01

    A study was carried out on the complexing and extracting properties of various dialkyldithiophosphoric acids towards ions of the 4f, 5f and 4d series. Sulphurated donors complex and extract ions of the 4f and 5f series less strongly than their oxygenated homologues. However the affinity of trivalent actinide ions for dialkythiophosphate ions is shown to be greater than that of lanthanides. The conditions of ruthenium extraction from nitric acid are defined [fr

  7. Acidic tumor microenvironment and pH-sensing G protein-coupled receptors.

    Science.gov (United States)

    Justus, Calvin R; Dong, Lixue; Yang, Li V

    2013-12-05

    The tumor microenvironment is acidic due to glycolytic cancer cell metabolism, hypoxia, and deficient blood perfusion. It is proposed that acidosis in the tumor microenvironment is an important stress factor and selection force for cancer cell somatic evolution. Acidic pH has pleiotropic effects on the proliferation, migration, invasion, metastasis, and therapeutic response of cancer cells and the function of immune cells, vascular cells, and other stromal cells. However, the molecular mechanisms by which cancer cells and stromal cells sense and respond to acidic pH in the tumor microenvironment are poorly understood. In this article the role of a family of pH-sensing G protein-coupled receptors (GPCRs) in tumor biology is reviewed. Recent studies show that the pH-sensing GPCRs, including GPR4, GPR65 (TDAG8), GPR68 (OGR1), and GPR132 (G2A), regulate cancer cell metastasis and proliferation, immune cell function, inflammation, and blood vessel formation. Activation of the proton-sensing GPCRs by acidosis transduces multiple downstream G protein signaling pathways. Since GPCRs are major drug targets, small molecule modulators of the pH-sensing GPCRs are being actively developed and evaluated. Research on the pH-sensing GPCRs will continue to provide important insights into the molecular interaction between tumor and its acidic microenvironment and may identify new targets for cancer therapy and chemoprevention.

  8. Antimicrobial activity of gallic acid against thermophilic Campylobacter is strain specific and associated with a loss of calcium ions.

    Science.gov (United States)

    Sarjit, Amreeta; Wang, Yi; Dykes, Gary A

    2015-04-01

    Gallic acid has been suggested as a potential antimicrobial for the control of Campylobacter but its effectiveness is poorly studied. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of gallic acid against Campylobacter jejuni (n = 8) and Campylobacter coli (n = 4) strains was determined. Gallic acid inhibited the growth of five C. jejuni strains and three C. coli strains (MIC: 15.63-250 μg mL(-1)). Gallic acid was only bactericidal to two C. coli strains (MBC: 125 and 62.5 μg mL(-1)). The mechanism of the bactericidal effect against these two strains (and selected non-susceptible controls) was investigated by determining decimal reduction times and by monitoring the loss of cellular content and calcium ions, and changes in cell morphology. Gallic acid did not result in a loss of cellular content or morphological changes in the susceptible strains as compared to the controls. Gallic acid resulted in a loss of calcium ions (0.58-1.53 μg mL(-1) and 0.54-1.17 μg mL(-1), respectively, over a 180 min period) from the susceptible strains but not the controls. Gallic acid is unlikely to be an effective antimicrobial against Campylobacter in a practical sense unless further interventions to ensure an effective bactericidal mode of action against all strains are developed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Quantum sensing of the phase-space-displacement parameters using a single trapped ion

    Science.gov (United States)

    Ivanov, Peter A.; Vitanov, Nikolay V.

    2018-03-01

    We introduce a quantum sensing protocol for detecting the parameters characterizing the phase-space displacement by using a single trapped ion as a quantum probe. We show that, thanks to the laser-induced coupling between the ion's internal states and the motion mode, the estimation of the two conjugated parameters describing the displacement can be efficiently performed by a set of measurements of the atomic state populations. Furthermore, we introduce a three-parameter protocol capable of detecting the magnitude, the transverse direction, and the phase of the displacement. We characterize the uncertainty of the two- and three-parameter problems in terms of the Fisher information and show that state projective measurement saturates the fundamental quantum Cramér-Rao bound.

  10. Free fatty acids-sensing G protein-coupled receptors in drug targeting and therapeutics.

    Science.gov (United States)

    Yonezawa, Tomo; Kurata, Riho; Yoshida, Kaori; Murayama, Masanori A; Cui, Xiaofeng; Hasegawa, Akihiko

    2013-01-01

    G protein-coupled receptor (GPCR) (also known as seven-transmembrane domain receptor) superfamily represents the largest protein family in the human genome. These receptors respond to various physiological ligands such as photons, odors, pheromones, hormones, ions, and small molecules including amines, amino acids to large peptides and steroids. Thus, GPCRs are involved in many diseases and the target of around half of all conventional drugs. The physiological roles of free fatty acids (FFAs), in particular, long-chain FFAs, are important for the development of many metabolic disease including obesity, diabetes, and atherosclerosis. In the past half decade, deorphanization of several GPCRs has revealed that GPR40, GPR41, GPR43, GPR84 and GPR120 sense concentration of extracellular FFAs with various carbon chain lengths. GPR40 and GPR120 are activated by medium- and long-chain FFAs. GPR84 is activated by medium- chain, but not long-chain, FFAs. GPR41 and GPR43 are activated by short-chain FFAs. GPR40 is highly expressed in pancreatic beta cells and plays a crucial role in FFAs-induced insulin secretion. GPR120 is mainly expressed in enteroendocrine cells and plays an important role for FFAs-induced glucagon-like peptide-1. GPR43 is abundant in leukocytes and adipose tissue, whilst GPR41 is highly expressed in adipose tissue, the pancreas and leukocytes. GPR84 is expressed in leukocytes and monocyte/macrophage. This review aims to shed light on the physiological roles and development of drugs targeting these receptors.

  11. Ion sense of polarization of the electromagnetic wave field in the electron whistler frequency band

    Directory of Open Access Journals (Sweden)

    B. Lundin

    Full Text Available It is shown that the left-hand (or ion-type sense of polarization can appear in the field interference pattern of two plane electron whistler waves. Moreover, it is demonstrated that the ion-type polarized wave electric fields can be accompanied by the presence at the same observation point of electron-type polarized wave magnetic fields. The registration of ion-type polarized fields with frequencies between the highest ion gyrofrequency and the electron gyrofrequency in a cold, overdense plasma is a sufficient indication for the existence of an interference wave pattern, which can typically occur near artificial or natural reflecting magnetospheric plasma regions, inside waveguides (as in helicon discharges, for example, in fields resonantly emitted by beams of charged particles or, in principle, in some self-sustained, nonlinear wave field structures. A comparison with the conventional spectral matrix data processing approach is also presented in order to facilitate the calculations of the analyzed polarization parameters.

    Key words. Ionosphere (wave propagation Radio science (waves in plasma Space plasma physics (general or miscellaneous

  12. The twisted ion-permeation pathway of a resting voltage-sensing domain.

    Science.gov (United States)

    Tombola, Francesco; Pathak, Medha M; Gorostiza, Pau; Isacoff, Ehud Y

    2007-02-01

    Proteins containing voltage-sensing domains (VSDs) translate changes in membrane potential into changes in ion permeability or enzymatic activity. In channels, voltage change triggers a switch in conformation of the VSD, which drives gating in a separate pore domain, or, in channels lacking a pore domain, directly gates an ion pathway within the VSD. Neither mechanism is well understood. In the Shaker potassium channel, mutation of the first arginine residue of the S4 helix to a smaller uncharged residue makes the VSD permeable to ions ('omega current') in the resting conformation ('S4 down'). Here we perform a structure-guided perturbation analysis of the omega conductance to map its VSD permeation pathway. We find that there are four omega pores per channel, which is consistent with one conduction path per VSD. Permeating ions from the extracellular medium enter the VSD at its peripheral junction with the pore domain, and then plunge into the core of the VSD in a curved conduction pathway. Our results provide a model of the resting conformation of the VSD.

  13. Ion sense of polarization of the electromagnetic wave field in the electron whistler frequency band

    Directory of Open Access Journals (Sweden)

    B. Lundin

    2002-08-01

    Full Text Available It is shown that the left-hand (or ion-type sense of polarization can appear in the field interference pattern of two plane electron whistler waves. Moreover, it is demonstrated that the ion-type polarized wave electric fields can be accompanied by the presence at the same observation point of electron-type polarized wave magnetic fields. The registration of ion-type polarized fields with frequencies between the highest ion gyrofrequency and the electron gyrofrequency in a cold, overdense plasma is a sufficient indication for the existence of an interference wave pattern, which can typically occur near artificial or natural reflecting magnetospheric plasma regions, inside waveguides (as in helicon discharges, for example, in fields resonantly emitted by beams of charged particles or, in principle, in some self-sustained, nonlinear wave field structures. A comparison with the conventional spectral matrix data processing approach is also presented in order to facilitate the calculations of the analyzed polarization parameters.Key words. Ionosphere (wave propagation Radio science (waves in plasma Space plasma physics (general or miscellaneous

  14. Rational Design of a Green-Light-Mediated Unimolecular Platform for Fast Switchable Acidic Sensing.

    Science.gov (United States)

    Zhou, Yunyun; Zou, Qi; Qiu, Jing; Wang, Linjun; Zhu, Liangliang

    2018-02-01

    A controllable sensing ability strongly connects to complex and precise events in diagnosis and treatment. However, imposing visible light into the molecular-scale mediation of sensing processes is restricted by the lack of structural relevance. To address this critical challenge, we present the rational design, synthesis, and in vitro studies of a novel cyanostyryl-modified azulene system for green-light-mediated fast switchable acidic sensing. The advantageous features of the design include a highly efficient green-light-driven Z/E-isomerization (a quantum yield up to 61.3%) for fast erasing chromatic and luminescent expressions and a superior compatibility with control of ratiometric protonation. Significantly, these merits of the design enable the development of a microfluidic system to perform a green-light-mediated reusable sensing function toward a gastric acid analyte in a miniaturized platform. The results may provide new insights for building future integrated green materials.

  15. Use of the ion exchange method for determination of stability constants of uranyl ions with three soil humic acids

    International Nuclear Information System (INIS)

    Tao Zuyi; Du Jinzhou

    1994-01-01

    The ion exchange equilibrium method proposed by Ardakani and Stevenson has not been widely used to determine the stability constants of metal-soil organic matter complexes. In this paper the Ardakani-Stevenson's method has been modified and the stability constants of uranyl ion complexes with three soil humic acids were determined by using the modified Ardakani-Stevenson's method. (orig.)

  16. Ca{sup 2+} ion sensing by a piperidin-4-one derivative and the effect of β-cyclodextrin complexation on the sensing

    Energy Technology Data Exchange (ETDEWEB)

    Sumithra, M.; Sivaraj, R.; Selvan, G. Tamil; Selvakumar, P. Mosae; Enoch, Israel V.M.V., E-mail: drisraelenoch@gmail.com

    2017-05-15

    In this paper, we report the turn-on fluorescence based Ca{sup 2+} ion sensing by an anthracene piperidin-4-one derivative. The compound is obtained using a simple two step synthesis. The compound is characterized using NMR and mass spectral methods. The host-guest complex formation of the compound with β-cyclodextrin is prepared and characterized using fluorescence and 2D ROESY spectroscopy. The compound forms the inclusion complex with a 1:1 stoichiometry. The structure of the host-guest complex is proposed. The Ca{sup 2+} ion selectivity of the compound in its free form and cyclodextrin-bound forms are studied. In both the forms, the piperidin-4-one derivative senses Ca{sup 2+} and in the case of the cyclodextrin encapsulated form it shows a better competitive binding of Ca{sup 2+} in the presence of other metal ions. - Highlights: •An anthracene iminoderivative of 3-methyl-2,6-diphenylpiperidin-4-one is synthesized. •The anthracene moiety of the compound is encapsulated by β-Cyclodextrin. •The compound senses Ca{sup 2+} ion both in water and β-CD media. •β-CD molecule does not interrupt the Ca{sup 2+} ion binding.

  17. Release of mineral ions in dental plaque following acid production.

    Science.gov (United States)

    Tanaka, M; Margolis, H C

    1999-03-01

    The release of appreciable amounts of calcium, phosphate and fluoride found in whole plaque into the plaque-fluid phase, following bacterial acid production, can potentially reduce the driving force for tooth demineralization. However, limited information is available on this topic, particularly on the release of fluoride. This study sought to determine the change in calcium, phosphate and fluoride concentrations in plaque fluid after sucrose exposure. 48 h overnight-fasted supragingival plaque samples were collected from all tooth surfaces (with the exception of the lower lingual anterior teeth) of one half of an individual mouth, following a 1 min water rinse. Plaque samples were then collected from the other half of the same mouth, following a 292 mM sucrose rinse. Plaque fluid was isolated by centrifugation and analysed for total calcium and phosphate (ion chromatography) and for free fluoride (ion-specific electrode). Samples were collected from seven individuals. Following sucrose exposure, plaque-fluid pH decreased significantly from 6.5+/- 0.3 to 5.4+/-0.2; calcium concentrations (mmol/l) also increased significantly (p Fluoride and phosphate concentrations in plaque fluid, however, did not increase significantly after sucrose exposure: mean concentrations (mmol/l) of fluoride after the water and sucrose rinses were 0.006+/-0.003 and 0.005+/-0.002, respectively, and mean phosphate concentrations (mmol/l) were 11.0+/-2.0 and 12.0+/-3.0, respectively. When results were expressed per wet plaque weight, phosphate concentrations were also found to increase significantly. The same trends were observed when additional plaque samples were treated in vitro with sucrose: fluoride-ion activity did not increase in plaque under in vivo-like conditions.

  18. Amino acid sensing in hypothalamic tanycytes via umami taste receptors.

    Science.gov (United States)

    Lazutkaite, Greta; Soldà, Alice; Lossow, Kristina; Meyerhof, Wolfgang; Dale, Nicholas

    2017-11-01

    Hypothalamic tanycytes are glial cells that line the wall of the third ventricle and contact the cerebrospinal fluid (CSF). While they are known to detect glucose in the CSF we now show that tanycytes also detect amino acids, important nutrients that signal satiety. Ca 2+ imaging and ATP biosensing were used to detect tanycyte responses to l-amino acids. The downstream pathway of the responses was determined using ATP receptor antagonists and channel blockers. The receptors were characterized using mice lacking the Tas1r1 gene, as well as an mGluR4 receptor antagonist. Amino acids such as Arg, Lys, and Ala evoke Ca 2+ signals in tanycytes and evoke the release of ATP via pannexin 1 and CalHM1, which amplifies the signal via a P2 receptor dependent mechanism. Tanycytes from mice lacking the Tas1r1 gene had diminished responses to lysine and arginine but not alanine. Antagonists of mGluR4 greatly reduced the responses to alanine and lysine. Two receptors previously implicated in taste cells, the Tas1r1/Tas1r3 heterodimer and mGluR4, contribute to the detection of a range of amino acids by tanycytes in CSF. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

  19. Recent Advances in Fluorescent Arylboronic Acids for Glucose Sensing

    Directory of Open Access Journals (Sweden)

    Jon Stefan Hansen

    2013-12-01

    Full Text Available Continuous glucose monitoring (CGM is crucial in order to avoid complications caused by change in blood glucose for patients suffering from diabetes mellitus. The long-term consequences of high blood glucose levels include damage to the heart, eyes, kidneys, nerves and other organs, among others, caused by malign glycation of vital protein structures. Fluorescent monitors based on arylboronic acids are promising candidates for optical CGM, since arylboronic acids are capable of forming arylboronate esters with 1,2-cis-diols or 1,3-diols fast and reversibly, even in aqueous solution. These properties enable arylboronic acid dyes to provide immediate information of glucose concentrations. Thus, the replacement of the commonly applied semi-invasive and non-invasive techniques relying on glucose binding proteins, such as concanavalin A, or enzymes, such as glucose oxidase, glucose dehydrogenase and hexokinases/glucokinases, might be possible. The recent progress in the development of fluorescent arylboronic acid dyes will be emphasized in this review.

  20. Surface plasmon resonance sensing of nucleic acids: A review

    Czech Academy of Sciences Publication Activity Database

    Šípová, Hana; Homola, Jiří

    -, č. 773 (2013), s. 9-23 ISSN 0003-2670 R&D Projects: GA MŠk(CZ) LH11102 Institutional support: RVO:67985882 Keywords : Surface plasmon resonance * Nucleic acid * Biosensor Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 4.517, year: 2013

  1. Portable, universal, and visual ion sensing platform based on the light emitting diode-based self-referencing-ion selective field-effect transistor.

    Science.gov (United States)

    Zhang, Xiaowei; Han, Yanchao; Li, Jing; Zhang, Libing; Jia, Xiaofang; Wang, Erkang

    2014-02-04

    In this work, a novel and universal ion sensing platform was presented, which enables the visual detection of various ions with high sensitivity and selectivity. Coaxial potential signals (millivolt-scale) of the sample from the self-referencing (SR) ion selective chip can be transferred into the ad620-based amplifier with an output of volt-scale potentials. The amplified voltage is high enough to drive a light emitting diode (LED), which can be used as an amplifier and indicator to report the sample information. With this double amplification device (light emitting diode-based self-referencing-ion selective field-effect transistor, LED-SR-ISFET), a tiny change of the sample concentration can be observed with a distinguishable variation of LED brightness by visual inspection. This LED-based luminescent platform provided a facile, low-cost, and rapid sensing strategy without the need of additional expensive chemiluminescence reagent and instruments. Moreover, the SR mode also endows this device excellent stability and reliability. With this innovative design, sensitive determination of K(+), H(+), and Cl(-) by the naked eye was achieved. It should also be noticed that this sensing strategy can easily be extended to other ions (or molecules) by simply integrating the corresponding ion (or molecule) selective electrode.

  2. Environmental sensing with optical fiber sensors processed with focused ion beam and atomic layer deposition

    Science.gov (United States)

    Flores, Raquel; Janeiro, Ricardo; Dahlem, Marcus; Viegas, Jaime

    2015-03-01

    We report an optical fiber chemical sensor based on a focused ion beam processed optical fiber. The demonstrated sensor is based on a cavity formed onto a standard 1550 nm single-mode fiber by either chemical etching, focused ion beam milling (FIB) or femtosecond laser ablation, on which side channels are drilled by either ion beam milling or femtosecond laser irradiation. The encapsulation of the cavity is achieved by optimized fusion splicing onto a standard single or multimode fiber. The empty cavity can be used as semi-curved Fabry-Pérot resonator for gas or liquid sensing. Increased reflectivity of the formed cavity mirrors can be achieved with atomic layer deposition (ALD) of alternating metal oxides. For chemical selective optical sensors, we demonstrate the same FIB-formed cavity concept, but filled with different materials, such as polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA) which show selective swelling when immersed in different solvents. Finally, a reducing agent sensor based on a FIB formed cavity partially sealed by fusion splicing and coated with a thin ZnO layer by ALD is presented and the results discussed. Sensor interrogation is achieved with spectral or multi-channel intensity measurements.

  3. Drosophila fatty acid taste signals through the PLC pathway in sugar-sensing neurons.

    Directory of Open Access Journals (Sweden)

    Pavel Masek

    Full Text Available Taste is the primary sensory system for detecting food quality and palatability. Drosophila detects five distinct taste modalities that include sweet, bitter, salt, water, and the taste of carbonation. Of these, sweet-sensing neurons appear to have utility for the detection of nutritionally rich food while bitter-sensing neurons signal toxicity and confer repulsion. Growing evidence in mammals suggests that taste for fatty acids (FAs signals the presence of dietary lipids and promotes feeding. While flies appear to be attracted to fatty acids, the neural basis for fatty acid detection and attraction are unclear. Here, we demonstrate that a range of FAs are detected by the fly gustatory system and elicit a robust feeding response. Flies lacking olfactory organs respond robustly to FAs, confirming that FA attraction is mediated through the gustatory system. Furthermore, flies detect FAs independent of pH, suggesting the molecular basis for FA taste is not due to acidity. We show that low and medium concentrations of FAs serve as an appetitive signal and they are detected exclusively through the same subset of neurons that sense appetitive sweet substances, including most sugars. In mammals, taste perception of sweet and bitter substances is dependent on phospholipase C (PLC signaling in specialized taste buds. We find that flies mutant for norpA, a Drosophila ortholog of PLC, fail to respond to FAs. Intriguingly, norpA mutants respond normally to other tastants, including sucrose and yeast. The defect of norpA mutants can be rescued by selectively restoring norpA expression in sweet-sensing neurons, corroborating that FAs signal through sweet-sensing neurons, and suggesting PLC signaling in the gustatory system is specifically involved in FA taste. Taken together, these findings reveal that PLC function in Drosophila sweet-sensing neurons is a conserved molecular signaling pathway that confers attraction to fatty acids.

  4. Effect of citric acid modification of aspen wood on sorption of copper ion

    Science.gov (United States)

    James D. McSweeny; Roger M. Rowell; Soo Hong Min

    2006-01-01

    Milled aspen wood was thermochemically modified with citric acid for the purpose of improving the copper (Cu2+) ion sorption capacity of the wood when tested in 24-hour equilibrium batch tests. The wood-citric acid adducts provided additional carboxyl groups to those in the native wood and substantially increased Cu2+ ion uptake of the modified wood compared with that...

  5. A complicated complex: Ion channels, voltage sensing, cell membranes and peptide inhibitors.

    Science.gov (United States)

    Zhang, Alan H; Sharma, Gagan; Undheim, Eivind A B; Jia, Xinying; Mobli, Mehdi

    2018-04-21

    Voltage-gated ion channels (VGICs) are specialised ion channels that have a voltage dependent mode of action, where ion conduction, or gating, is controlled by a voltage-sensing mechanism. VGICs are critical for electrical signalling and are therefore important pharmacological targets. Among these, voltage-gated sodium channels (Na V s) have attracted particular attention as potential analgesic targets. Na V s, however, comprise several structurally similar subtypes with unique localisations and distinct functions, ranging from amplification of action potentials in nociception (e.g. Na V 1.7) to controlling electrical signalling in cardiac function (Na V 1.5). Understanding the structural basis of Na V function is therefore of great significance, both to our knowledge of electrical signalling and in development of subtype and state selective drugs. An important tool in this pursuit has been the use of peptides from animal venoms as selective Na V modulators. In this review, we look at peptides, particularly from spider venoms, that inhibit Na V s by binding to the voltage sensing domain (VSD) of this channel, known as gating modifier toxins (GMT). In the first part of the review, we look at the structural determinants of voltage sensing in VGICs, the gating cycle and the conformational changes that accompany VSD movement. Next, the modulation of the analgesic target Na V 1.7 by GMTs is reviewed to develop bioinformatic tools that, based on sequence information alone, can identify toxins that are likely to inhibit this channel. The same approach is also used to define VSD sequences, other than that from Na V 1.7, which are likely to be sensitive to this class of toxins. The final section of the review focuses on the important role of the cellular membrane in channel modulation and also how the lipid composition affects measurements of peptide-channel interactions both in binding kinetics measurements in solution and in cell-based functional assays. Copyright © 2018

  6. Gas-phase ion/ion reactions of peptides and proteins: acid/base, redox, and covalent chemistries.

    Science.gov (United States)

    Prentice, Boone M; McLuckey, Scott A

    2013-02-01

    Gas-phase ion/ion reactions are emerging as useful and flexible means for the manipulation and characterization of peptide and protein biopolymers. Acid/base-like chemical reactions (i.e., proton transfer reactions) and reduction/oxidation (redox) reactions (i.e., electron transfer reactions) represent relatively mature classes of gas-phase chemical reactions. Even so, especially in regards to redox chemistry, the widespread utility of these two types of chemistries is undergoing rapid growth and development. Additionally, a relatively new class of gas-phase ion/ion transformations is emerging which involves the selective formation of functional-group-specific covalent bonds. This feature details our current work and perspective on the developments and current capabilities of these three areas of ion/ion chemistry with an eye towards possible future directions of the field.

  7. Process for the conversion of sugars to lactic acid and 2-hydroxy-3-butenoic acid or esters thereof comprising a metallo-silicate material and a metal ion

    DEFF Research Database (Denmark)

    2015-01-01

    A process for the preparation of lactic acid and 2-hydroxy- 3-butenoic acid or esters thereof from a sugar in the presence of a metallo-silicate material, a metal ion and a solvent, wherein the metal ion is selected from one or more of the group consisting of potassium ions, sodium ions, lithium...

  8. Determination of water-soluble forms of oxalic and formic acids in soils by ion chromatography

    Science.gov (United States)

    Karicheva, E.; Guseva, N.; Kambalina, M.

    2016-03-01

    Carboxylic acids (CA) play an important role in the chemical composition origin of soils and migration of elements. The content of these acids and their salts is one of the important characteristics for agrochemical, ecological, ameliorative and hygienic assessment of soils. The aim of the article is to determine water-soluble forms of same carboxylic acids — (oxalic and formic acids) in soils by ion chromatography with gradient elution. For the separation and determination of water-soluble carboxylic acids we used reagent-free gradient elution ion-exchange chromatography ICS-2000 (Dionex, USA), the model solutions of oxalate and formate ions, and leachates from soils of the Kola Peninsula. The optimal gradient program was established for separation and detection of oxalate and formate ions in water solutions by ion chromatography. A stability indicating method was developed for the simultaneous determination of water-soluble organic acids in soils. The method has shown high detection limits such as 0.03 mg/L for oxalate ion and 0.02 mg/L for formate ion. High signal reproducibility was achieved in wide range of intensities which correspond to the following ion concentrations: from 0.04 mg/g to 10 mg/L (formate), from 0.1 mg/g to 25 mg/L (oxalate). The concentration of formate and oxalate ions in soil samples is from 0.04 to 0.9 mg/L and 0.45 to 17 mg/L respectively.

  9. DMPD: Nucleic acid-sensing TLRs as modifiers of autoimmunity. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available S. J Immunol. 2006 Nov 15;177(10):6573-8. (.png) (.svg) (.html) (.csml) Show Nucleic acid-sensing TLRs as mo...way - PNG File (.png) SVG File (.svg) HTML File (.html) CSML File (.csml) Open .csml file with CIOPlayer Ope

  10. DMPD: Plasmacytoid dendritic cells: sensing nucleic acids in viral infection andautoimmune diseases. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 18641647 Plasmacytoid dendritic cells: sensing nucleic acids in viral infection andautoimmune dise... (.csml) Show Plasmacytoid dendritic cells: sensing nucleic acids in viral infection andautoimmune diseases....iral infection andautoimmune diseases. Authors Gilliet M, Cao W, Liu YJ. Publication Nat Rev Immunol. 2008 A

  11. Acid leaching of mixed spent Li-ion batteries

    Directory of Open Access Journals (Sweden)

    A.A. Nayl

    2017-05-01

    Full Text Available Acid leaching for different types of mixed spent Li-ion mobile batteries is carried out after alkali decomposition using NH4OH followed by H2SO4 + H2O2 leaching. In the alkali decomposition step, the effects of reaction time, NH4OH concentration, liquid/solid mass ratio and reaction temperature on the decomposition process are investigated to remove Al, Cu, Mn, Ni, Co, and Li. After alkaline treatment, the alkali paste is treated to leach the remaining metals using H2SO4 + H2O2. The significant effects of reaction time, acid concentration, H2O2 concentration, liquid/solid mass ratios and reaction temperature on the leaching rate are studied. More than 97% of Al, Mn, Ni, Co, and Li and about 65% Cu are leached in two stages. Kinetic analysis shows that, the data fit with chemical reaction control mechanism and the activation energies for the investigated metals using the Arrhenius equation ranged from 30.1 to 41.4 kJ/mol. Recovered metals are precipitated from the leaching liquor at varying pH values using NaOH solution and Na2CO3. Firstly, Mn is precipitated as MnCO3 at pH = 7.5. Secondly, at pH = 9.0, nickel is precipitated as NiCO3. Thirdly, as the pH of the leaching liquor reaches 11–12, Co(OH2 is precipitated and the remaining Li is readily precipitated as Li2CO3 using a saturated Na2CO3 solution. Based on the experimental data, a flow sheet is developed and tested for the recovery process.

  12. Mechanisms of amino acid sensing in mTOR signaling pathway

    OpenAIRE

    Kim, Eunjung

    2009-01-01

    Amino acids are fundamental nutrients for protein synthesis and cell growth (increase in cell size). Recently, many compelling evidences have shown that the level of amino acids is sensed by extra- or intra-cellular amino acids sensor(s) and regulates protein synthesis/degradation. Mammalian target of rapamycin complex 1 (mTORC1) is placed in a central position in cell growth regulation and dysregulation of mTOR signaling pathway has been implicated in many serious human diseases including ca...

  13. Supercooling Agent Icilin Blocks a Warmth-Sensing Ion Channel TRPV3

    Directory of Open Access Journals (Sweden)

    Muhammad Azhar Sherkheli

    2012-01-01

    Full Text Available Transient receptor potential vanilloid subtype 3 (TRPV3 is a thermosensitive ion channel expressed in a variety of neural cells and in keratinocytes. It is activated by warmth (33–39°C, and its responsiveness is dramatically increased at nociceptive temperatures greater than 40°C. Monoterpenoids and 2-APB are chemical activators of TRPV3 channels. We found that Icilin, a known cooling substance and putative ligand of TRPM8, reversibly inhibits TRPV3 activity at nanomolar concentrations in expression systems like Xenopus laeves oocytes, HEK-293 cells, and in cultured human keratinocytes. Our data show that icilin's antagonistic effects for the warm-sensitive TRPV3 ion channel occurs at very low concentrations. Therefore, the cooling effect evoked by icilin may at least in part be due to TRPV3 inhibition in addition to TRPM8 potentiation. Blockade of TRPV3 activity by icilin at such low concentrations might have important implications for overall cooling sensations detected by keratinocytes and free nerve endings in skin. We hypothesize that blockage of TRPV3 might be a signal for cool-sensing systems (like TRPM8 to beat up the basal activity resulting in increased cold perception when warmth sensors (like TRPV3 are shut off.

  14. Effects of increasing number of rings on the ion sensing ability of CdSe quantum dots: a theoretical study

    Science.gov (United States)

    Malik, Pragati; Kakkar, Rita

    2018-04-01

    A computational study on the structural and electronic properties of a special class of artificial atoms, known as quantum dots, has been carried out. These are semiconductors with unique optical and electronic properties and have been widely used in various applications, such as bio-sensing, bio-imaging, and so on. We have considered quantum dots belonging to II-VI types of semiconductors, due to their wide band gap, possession of large exciton binding energies and unique optical and electronic properties. We have studied their applications as chemical ion sensors by beginning with the study of the ion sensing ability of (CdSe) n ( n = 3, 6, 9 which are in the size range of 0.24, 0.49, 0.74 nm, respectively) quantum dots for cations of the zinc triad, namely Zn2+, Cd2+, Hg2+, and various anions of biological and environmental importance, and studied the effect of increasing number of rings on their ion sensing ability. The various structural, electronic, and optical properties, their interaction energies, and charge transfer on interaction with metal ions and anions have been calculated and reported. Our studies indicate that the CdSe quantum dots can be employed as sensors for both divalent cations and anions, but they can sense cations better than anions.

  15. A procedure for reducing the concentration of hydrogen ions in acid anionic eluate and equipment therefore

    International Nuclear Information System (INIS)

    Parobek, P.; Baloun, S.; Plevac, S.

    1989-01-01

    The method is described of reducing the concentration of hydrogen ions in acid anionic eluate produced in the separation of uranium or other metals, in which anion exchanger elution, precipitation, filtration and precipitate and anion exchanger washing are used. The technological line for such elution comprises at least one ion exchange column and at least one container. They together form the first and the second stages of preparation of the acid anion elution solution, the sorption-elution separation of hydrogen ions on an cation exchanger being inserted between them. The preparation of the solution is divide into two stages. In the first stage, the acid and part of the solution for the preparation of the acid anion elution solution are supplied. The resulting enriched acid elution solution is fe onto the cation exchanger where the hydrogen ion concentration i reduced. It is then carried into the second stage where it is mixed with the remaining part of the solution. (B.S.)

  16. Behaviour of Pu-IV with various ion exchangers in solutions containing nitric acid and oxalates

    International Nuclear Information System (INIS)

    Walter, E.; Ali, S.A.

    1982-02-01

    The distribution of Pu-IV on the ion exchangers Dowex 50W-X8, Dowex 1-X8 und Dowex Chelating Resin Al-X8 in the presence of various concentrations of nitric acid and oxalate were investigated. The results indicate that nitric acid and oxalic acid influence each other during complexation of Pu-IV with oxalate ions solutions containing nitric acid it is not possible to neglect the formation of Pu-IV nitrate complexes. The complex Pu(IV) (C 2 O 4 ) 3 2 - only is formed in solutions containing low nitric acid and high oxalic acid concentrations. The separation of Pu-IV in Dowex Chelating Resin from nitric acid solution in the presence of higher oxalate concentrations is possible, provided that the nitric acid concentration is lower than 0.25 molar [fr

  17. Efficient Imaging and Real-Time Display of Scanning Ion Conductance Microscopy Based on Block Compressive Sensing

    Science.gov (United States)

    Li, Gongxin; Li, Peng; Wang, Yuechao; Wang, Wenxue; Xi, Ning; Liu, Lianqing

    2014-07-01

    Scanning Ion Conductance Microscopy (SICM) is one kind of Scanning Probe Microscopies (SPMs), and it is widely used in imaging soft samples for many distinctive advantages. However, the scanning speed of SICM is much slower than other SPMs. Compressive sensing (CS) could improve scanning speed tremendously by breaking through the Shannon sampling theorem, but it still requires too much time in image reconstruction. Block compressive sensing can be applied to SICM imaging to further reduce the reconstruction time of sparse signals, and it has another unique application that it can achieve the function of image real-time display in SICM imaging. In this article, a new method of dividing blocks and a new matrix arithmetic operation were proposed to build the block compressive sensing model, and several experiments were carried out to verify the superiority of block compressive sensing in reducing imaging time and real-time display in SICM imaging.

  18. Single-crystal Au microflakes modulated by amino acids and their sensing and catalytic properties.

    Science.gov (United States)

    Li, Mingjie; Wu, Xiaochen; Zhou, Jiyu; Kong, Qingshan; Li, Chaoxu

    2016-04-01

    Single-crystal Au microflakes with the planar area over 10(3)μm(2) (i.e. being accessible to the human eye resolution) were synthesized in an environment-friendly route by directing two-dimensional growth of Au nanocrystals into macroscopic scales with amino acids as both reducing agents and capping agents. Side groups of amino acids were found to be a determinant parameter to tune the dimension and size of Au single crystals. The successful synthesis of Au microflakes provides an unprecedented opportunity to bridge nanotechnology and macroscopic devices, and hereby to start a new scenario of exploring their unique properties and applications in optoelectronic devices and bio-sensing fields across multiple length scales. For example, Au microflakes respond to air humidity upon depositing on films of chitin nanofibrils, and sense various physiological molecules as electrode materials of biosensors. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Ester Sensing with Poly (Aniline-co-m-aminobenzoic Acid Deposited on Poly (Vinyl Alcohol

    Directory of Open Access Journals (Sweden)

    S. ADHIKARI

    2011-02-01

    Full Text Available Poly (aniline-co-m-aminobenzoic acid was deposited on poly (vinyl alcohol film by in situ oxidative polymerization of the monomers aniline and m-aminobenzoic acid. Sensing experiments were performed on the composite film with the injection of various concentrations of hexenyl acetate and hexenyl butyrate at room temperature. The sensor responded rapidly and reversibly in the presence of hexenyl acetate and hexenyl butyrate vapors which was detected by resistance change of the composite film upon exposure to the vapor. Selectivity tests revealed that the sensor selectively responded to hexenyl butyrate compared to hexenyl acetate. The sensing response has been explained on the basis of FT-IR spectroscopic analysis of the polymer film before and after exposure to the ester vapor.

  20. Cation mobility in H+/Na+ ion exchange products of acid tantalum and zirconium phosphates

    International Nuclear Information System (INIS)

    Tarnopol'skij, V.A.; Yaroslavtsev, A.B.

    2000-01-01

    Ionic conductivity of Na + /H + exchange products on acid zirconium phosphate with different substitution degree and on acid tantalum phosphate, where ion exchange occurs via formation of a continuous series of solid solutions, was studied by the method of conductometry. It was ascertained that ionic conductivity decreases monotonously with growth in substitution degree of H + for Na + in acid tantalum phosphate. Anomalous increase in ionic conductivity of ion exchange products on acid zirconium phosphate with a low substitution degree has been detected for the first time. Formation of a double electric layer with a high concentration of cationic defects on the interface surface is the reason for increase in ionic conductivity [ru

  1. Target-Triggered Switching on and off the Luminescence of Lanthanide Coordination Polymer Nanoparticles for Selective and Sensitive Sensing of Copper Ions in Rat Brain.

    Science.gov (United States)

    Huang, Pengcheng; Wu, Fangying; Mao, Lanqun

    2015-07-07

    Copper ions (Cu(2+)) in the central nervous system play a crucial role in the physiological and pathological events, so simple, selective, and sensitive detection of cerebral Cu(2+) is of great importance. In this work, we report a facile yet effective fluorescent method for sensing of Cu(2+) in rat brain using one kind of lanthanide coordination polymer nanoparticle, adenosine monophosphate (AMP) and terbium ion (Tb(3+)), i.e., AMP-Tb, as the sensing platform. Initially, a cofactor ligand, 5-sulfosalicylic acid (SSA), as the sensitizer, was introduced into the nonluminescent AMP-Tb suspension, resulting in switching on the luminescence of AMP-Tb by the removal of coordinating water molecules and concomitant energy transfer from SSA to Tb(3+). The subsequent addition of Cu(2+) into the resulting SSA/AMP-Tb can strongly quench the fluorescence because the specific coordination interaction between SSA and Cu(2+) rendered energy transfer from SSA to Tb(3+) inefficient. The decrease ratio of the fluorescence intensities of SSA/AMP-Tb at 550 nm show a linear relationship for Cu(2+) within the concentration range from 1.5 to 24 μM with a detection limit of 300 nM. The method demonstrated here is highly selective and is free from the interference of metal ions, amino acids, and the biological species commonly existing in the brain such as dopamine, lactate, and glucose. Eventually, by combining the microdialysis technique, the present method has been successfully applied in the detection of cerebral Cu(2+) in rat brain with the basal dialysate level of 1.91 ± 0.40 μM (n = 3). This method is very promising to be used for investigating the physiological and pathological events that cerebral Cu(2+) participates in.

  2. Medium dependent dual turn on/turn off fluorescence sensing for Cu2 + ions using AMI/SDS assemblies

    Science.gov (United States)

    Gujar, Varsha B.; Ottoor, Divya

    2017-02-01

    Behavior of Amiloride (AMI) as a metal ion sensor in anionic surfactant assemblies of varying concentrations at different pH is depicted in this work. From a non-sensor fluorophore, AMI has been transformed in to a tunable fluorosensor for Cu2 + ions in various SDS concentrations. At premicellar concentration of SDS, ion-pair complex is expected to be formed between AMI and SDS due to electrostatic interactions between them. However at CMC concentrations of SDS, fluorescence intensity of AMI is greatly enhanced with red shift in emission, due to the incorporation of AMI molecule in the hydrophobic micellar interface. The behavior of metal sensing by AMI-SDS assemblies gives rise to several interesting observations. Micellation of SDS has been greatly enhanced by increasing copper ion concentrations, as these counter ions screens the charge on monomers of SDS which lead to the aggregation at premicellar concentrations only. Concentrations and pH dependent discrete trends of interactions between SDS-AMI and SDS-Cu2 + ions, have given tunable fluorescence responses (fluorescence turn on/turn off) of AMI for added Cu2 + ions. The electrostatic interaction between the metal cations and the anionic surfactants is the driving force for bringing the metal ions near to the vicinity of micelle where AMI resides. Thus, a comprehensive understanding of the mechanism related to the 'turn on-turn off' fluorescence response of AMI with respect to pH and SDS concentration for effective Cu2 + ion sensing is illustrated in this work.

  3. Electrochemical sensing of tumor suppressor protein p53-deoxyribonucleic acid complex stability at an electrified interface

    Czech Academy of Sciences Publication Activity Database

    Paleček, Emil; Černocká, Hana; Ostatná, Veronika; Navrátilová, Lucie; Brázdová, Marie

    2014-01-01

    Roč. 828, MAY2014 (2014), s. 1-8 ISSN 0003-2670 R&D Projects: GA ČR(CZ) GAP301/11/2055; GA ČR(CZ) GA13-00956S; GA ČR(CZ) GA13-36108S Institutional support: RVO:68081707 Keywords : Deoxyribonucleic acid-protein binding * Tumor suppressor protein p53 * Electrochemical sensing Subject RIV: BO - Biophysics Impact factor: 4.513, year: 2014

  4. Determination of aminoglycoside antibiotics using complex compounds of chromotropic acid bisazoderivatives with rare earth ions

    International Nuclear Information System (INIS)

    Alykov, N.M.

    1981-01-01

    Studies of complex formation of bisazo derivatives of chromotropic acid with rare earth ions and aminoglycoside antibiotics have made it possible to choose carboxyarsenazo, orthanyl R and carboxynitrazo as highly sensitive reagents for determining aminoglycoside antibiotics. Conditions have been found for the formation of precipitates of different-ligand complexes containing rare earth ions, bisazo derivatives of chromotropic acid and aminogylcoside antibiotics. A procedure has been worked out of determining the antibiotics in biological samples with carboxyarsenazo [ru

  5. The use of ion chromatography for the determination of impurities in crude phosphoric acid

    International Nuclear Information System (INIS)

    Pires, M.A.F.; Atalla, L.T.; Abrao, A.

    1988-07-01

    The determination of fluoride, nitrate, sulphate and phosphate ions in crude phosphoric acid by means of ion chromatography is described. A previous separation of interferent cations was made by using a cationic resin or EDTA complexation. The last alternative allowed more reproductible results. The technique described is very quick and is being applied for the simultaneous determination of impurities in phosphoric acid and its own phosphospate concentration. The method is quick and has good reprodutibility. (author) [pt

  6. Nano and Mesoscale Ion and Water Transport in Perfluorosulfonic AcidMembranes

    Science.gov (United States)

    2017-10-01

    Nano- and Mesoscale Ion and Water Transport in Perfluorosulfonic-Acid Membranes A. R. Crothers a,b , C. J. Radke a,b , A. Z. Weber a a...Berkeley, CA 94720, USA Water and aqueous cations transport along multiple length scales in perfluorosulfonic-acid membranes. Molecular interactions...as a function of hydration. A resistor network upscales the nanoscale properties to predict effective membrane ion and water transport and their

  7. Removing ferric ions from concentrated acid leaching solution of an uranium ore by jarosite

    International Nuclear Information System (INIS)

    Song Huanbi; Hu Yezang

    1997-01-01

    The author expounds the fundamental rules of removing ferric ions by jarosite and presents results of removing ferric ions from concentrated acid curing-trickle leaching solution of an uranium ore. It turns out that the method can be applied to uranium hydrometallurgical process effectively

  8. Preparation and ion sensing property of the self-assembled microgels by QCM

    Directory of Open Access Journals (Sweden)

    Cao Zheng

    2018-03-01

    Full Text Available The polyanion polystyrene sulfonate (PSS, the polycation poly (allylamine hydrochloride (PAH, and the anionic poly (N-isopropylacrylamide-co-acrylic acid [P(NIPAM-co-AA] microgels were self-assembled onto the polyethylene imine (PEI adsorbed gold surfaces of quartz crystal microbalance (QCM because of the electrostatic attractions. The interactions of various metal particles including Ca2+, Bi3+, Cu2+, Zn2+, Ni2+, Sn2+, Co2+, and Cd2+ with the obtained PEI/PSS/PAH/microgel layer in aqueous solutions were evaluated by QCM. The PEI/PSS/PAH/Microgel covered QCM sensor demonstrates the lowest detection limit of 0.1 ppm in aqueous solutions and the obviously linear connection between the frequency response and Ni2+ concentration from 0.1 to 20 ppm, which is due to the complexation of Ni2+ with the carboxyl groups of microgels. Atomic force microscopy (AFM was used to reveal the morphology and stability of the self-assembled polyelectrolyte/microgel layer before and after adsorbing heavy metal ions. These self-assembled materials of polyelectrolyte/microgel layer will be helpful for manufacturing ion-selective materials for separation and identification purposes.

  9. Equilibrium studies on interactions of rare earth ions with phytic acid

    International Nuclear Information System (INIS)

    Siddiqi, K.S.; Shah, S.A.; Aqra, F.M.A.M.; Tabassum, S.; Zaidi, S.A.A.; Benlian, D.

    1993-01-01

    The interaction between phytic acid and trivalent rare earth metal ions, viz., Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Gd 3+ , Tb 3+ , Dy 3+ and HO 3+ has been investigated potentiometrically at 25degC. The proton-ligand stability constants (pK Y H ) of phytic acid and the stability constants (logK) of metal complexes formed in aqueous medium (μ = 0.1 M NaClO 4 ) have been evaluated. The results indicate that eight protons of phytic acid are highly acidic, two are weakly acidic and two very weakly acidic, titrable in the pH ranges 1.2-4.9, 5.0-8.15 and 8.3-11.0 respectively. The stability of each phytic acid-lanthanide ion complex decreases with an increase in pH and follows the usual trend through the series. (author). 11 refs., 2 tabs

  10. Melt quenched vanadium oxide embedded in graphene oxide sheets as composite electrodes for amperometric dopamine sensing and lithium ion battery applications

    Science.gov (United States)

    Sreejesh, M.; Shenoy, Sulakshana; Sridharan, Kishore; Kufian, D.; Arof, A. K.; Nagaraja, H. S.

    2017-07-01

    Electrochemical sensors and lithium-ion batteries are two important topics in electrochemistry that have attracted much attention owing to their extensive applications in enzyme-free biosensors and portable electronic devices. Herein, we report a simple hydrothermal approach for synthesizing composites of melt quenched vanadium oxide embedded on graphene oxide of equal proportion (MVGO50) for the fabrication of electrodes for nonenzymatic amperometic dopamine sensor and lithium-ion battery applications. The sensing performance of MVGO50 electrodes through chronoamperometry studies in 0.1 M PBS solution (at pH 7) over a wide range of dopamine concentration exhibited a highest sensitivity of 25.02 μA mM-1 cm-2 with the lowest detection limit of 0.07 μM. In addition, the selective sensing capability of MVGO50 was also tested through chronoamperometry studies by the addition of a very small concentration of dopamine (10 μM) in the presence of a fairly higher concentration of uric acid (10 mM) as the interfering species. Furthermore, the reversible lithium cycling properties of MVGO50 are evaluated by galvanostatic charge-discharge cycling studies. MVGO50 electrodes exhibited enhanced rate capacity of up to 200 mAhg-1 at a current of 0.1C rate and remained stable during cycling. These results indicate that MVGO composites are potential candidates for electrochemical device applications.

  11. Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid.

    Science.gov (United States)

    Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

    2016-07-05

    The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane.

  12. Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid

    Science.gov (United States)

    Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

    2016-01-01

    The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane. PMID:27330112

  13. Application of ion beam analysis to the selective sublimation processing of thin films for gas sensing

    International Nuclear Information System (INIS)

    Vomiero, A.; Scian, C.; Della Mea, G.; Guidi, V.; Martinelli, G.; Schiffrer, G.; Comini, E.; Ferroni, M.; Sberveglieri, G.

    2006-01-01

    Ion beam analysis was successfully applied to a novel technique, named selective sublimation process (SSP), for deposition of nanostructured gas-sensing films through reactive sputtering. The method consists of the co-deposition of a mixed oxide, one of which has a relatively low sublimation temperature. Annealing at suitable temperature causes the sublimation of the most volatile compound, leaving a layer with adjustable composition. The appropriate choice of thermal treatments and the consequent tailoring of the composition play a crucial role in the determination of the microstructural properties. We developed a model based on diffusion equations that provides a useful guide to control the deposition and processing parameters and we applied the model on the systems TiO 2 -WO 3 and TiO 2 -MoO 3 . Rutherford backscattering (RBS) was demonstrated to be effective for the characterization of the diffusion and sublimation processes during SSP. Experimental results fully agree with theoretical prediction, and allowed the calculation of all the parameters involved in SSP

  14. Formation and Characterization of Self-Assembled Phenylboronic Acid Derivative Monolayers toward Developing Monosaccaride Sensing-Interface

    Directory of Open Access Journals (Sweden)

    Kwangnak Koh

    2007-08-01

    Full Text Available We designed and synthesized phenylboronic acid as a molecular recognitionmodel system for saccharide detection. The phenylboronic acid derivatives that haveboronic acid moiety are well known to interact with saccharides in aqueous solution; thus,they can be applied to a functional interface of saccharide sensing through the formation ofself-assembled monolayer (SAM. In this study, self-assembled phenylboronic acidderivative monolayers were formed on Au surface and carefully characterized by atomicforce microscopy (AFM, Fourier transform infrared reflection absorption spectroscopy(FTIR-RAS, surface enhanced Raman spectroscopy (SERS, and surface electrochemicalmeasurements. The saccharide sensing application was investigated using surface plasmonresonance (SPR spectroscopy. The phenylboronic acid monolayers showed goodsensitivity of monosaccharide sensing even at the low concentration range (1.0 × 10-12 M.The SPR angle shift derived from interaction between phenylboronic acid andmonosaccharide was increased with increasing the alkyl spacer length of synthesizedphenylboronic acid derivatives.

  15. Ion exchange system design for removal of heavy metals from acid mine drainage wastewater

    Directory of Open Access Journals (Sweden)

    R. S. Sapkal

    2010-11-01

    Full Text Available This paper discusses the methodology used to determine the optimal ion-exchange column size to process all separate batchesof feeds from acid mine drainage wastewater.The optimal design ensures the best utilization of resin material and therefore results in a minimum amount of spent resins.Ion exchanger materials have been studied for removing heavy metals from a metal bearing wastes. For the current treatment,a facility has been designed for the removal of heavy metals from the acid mine drainage (AMD waste by the ion-exchange technology.

  16. Interaction of metal ions and amino acids - Possible mechanisms for the adsorption of amino acids on homoionic smectite clays

    Science.gov (United States)

    Gupta, A.; Loew, G. H.; Lawless, J.

    1983-01-01

    A semiempirical molecular orbital method is used to characterize the binding of amino acids to hexahydrated Cu(2+) and Ni(2+), a process presumed to occur when they are adsorbed in the interlamellar space of homoionic smectite clays. Five alpha-amino acids, beta-alanine, and gamma-aminobutyric acid were used to investigate the metal ion and amino acid specificity in binding. It was assumed that the alpha, beta, and gamma-amino acids would bind as bidentate anionic ligands, forming either 1:1 or 1:2 six-coordinated five, six, and seven-membered-ring chelate complexes, respectively. Energies of complex formation, optimized geometries, and electron and spin distribution were determined; and steric constraints of binding of the amino acids to the ion-exchanged cations in the interlamellar spacing of a clay were examined. Results indicate that hexahydrated Cu(2+) forms more stable complexes than hexahydrated Ni(2+) with all the amino acids studied. However, among these amino acids, complex formation does not favor the adsorption of the biological subset. Calculated energetics of complex formation and steric constraints are shown to predict that 1:1 rather than 1:2 metal-amino acid complexes are generally favored in the clay.

  17. Bicarbonate sensing in mouse cortical astrocytes during extracellular acid/base disturbances

    Science.gov (United States)

    Naoshin, Zinnia; Defren, Sabrina; Schmaelzle, Jana; Weber, Tobias; Schneider, Hans‐Peter

    2017-01-01

    Key points The present study suggests that the electrogenic sodium–bicarbonate cotransporter, NBCe1, supported by carbonic anhydrase II, CAII, provides an efficient mechanism of bicarbonate sensing in cortical astrocytes. This mechanism is proposed to play a major role in setting the pHi responses to extracellular acid/base challenges in astrocytes.A decrease in extracellular [HCO3 −] during isocapnic acidosis and isohydric hypocapnia, or an increase in intracellular [HCO3 −] during hypercapnic acidosis, was effectively sensed by NBCe1, which carried bicarbonate out of the cells under these conditions, and caused an acidification and sodium fall in WT astrocytes, but not in NBCe1‐knockout astrocytes.Isocapnic acidosis, hypercapnic acidosis and isohydric hypocapnia evoked inward currents in NBCe1‐ and CAII‐expressing Xenopus laevis oocytes, but not in native oocytes, suggesting that NBCe1 operates in the outwardly directed mode under these conditions consistent with our findings in astrocytes.We propose that bicarbonate sensing of astrocytes may have functional significance during extracellular acid/base disturbances in the brain, as it not only alters intracellular pH/[HCO3 −]‐dependent functions of astrocytes, but also modulates the extracellular pH/[HCO3 −] in brain tissue. Abstract Extracellular acid/base status of the mammalian brain undergoes dynamic changes during many physiological and pathological events. Although intracellular pH (pHi) of astrocytes responds to extracellular acid/base changes, the mechanisms mediating these changes have remained unresolved. We have previously shown that the electrogenic sodium–bicarbonate cotransporter, NBCe1, is a high‐affinity bicarbonate carrier in cortical astrocytes. In the present study, we investigated whether NBCe1 plays a role in bicarbonate sensing in astrocytes, and in determining the pHi responses to extracellular acid/base challenges. We measured changes in intracellular H+ and Na+ in

  18. Study of the mechanism and kinetics of the reduction of uranyl ions in phosphoric acid solutions

    International Nuclear Information System (INIS)

    El Kacemi, K.; Tyburce, B.; Belcadi, S.

    1982-01-01

    The electrochemical reduction of uranyl ions in 0.1 to 9 M phosphoric acid has been investigated by polarography, cyclic voltammetry, chronopotentiometry and potentiostatic coulometry. In concentrated phosphoric acid solutions (H 3 PO 4 3 PO 4 concentrations. So, when the concentration of U(VI) increases and/or that of H 3 PO 4 reduces, the system becomes reversible. (author)

  19. Ion-neutral Clustering of Bile Acids in Electrospray Ionization Across UPLC Flow Regimes

    Science.gov (United States)

    Brophy, Patrick; Broeckling, Corey D.; Murphy, James; Prenni, Jessica E.

    2018-02-01

    Bile acid authentic standards were used as model compounds to quantitatively evaluate complex in-source phenomenon on a UPLC-ESI-TOF-MS operated in the negative mode. Three different diameter columns and a ceramic-based microfluidic separation device were utilized, allowing for detailed descriptions of bile acid behavior across a wide range of flow regimes and instantaneous concentrations. A custom processing algorithm based on correlation analysis was developed to group together all ion signals arising from a single compound; these grouped signals produce verified compound spectra for each bile acid at each on-column mass loading. Significant adduction was observed for all bile acids investigated under all flow regimes and across a wide range of bile acid concentrations. The distribution of bile acid containing clusters was found to depend on the specific bile acid species, solvent flow rate, and bile acid concentration. Relative abundancies of each cluster changed non-linearly with concentration. It was found that summing all MS level (low collisional energy) ions and ion-neutral adducts arising from a single compound improves linearity across the concentration range (0.125-5 ng on column) and increases the sensitivity of MS level quantification. The behavior of each cluster roughly follows simple equilibrium processes consistent with our understanding of electrospray ionization mechanisms and ion transport processes occurring in atmospheric pressure interfaces. [Figure not available: see fulltext.

  20. Boronic Acid-Based Approach for Separation and Immobilization of Glycoproteins and Its Application in Sensing

    Directory of Open Access Journals (Sweden)

    Lin Liu

    2013-10-01

    Full Text Available Glycoproteins influence a broad spectrum of biological processes including cell-cell interaction, host-pathogen interaction, or protection of proteins against proteolytic degradation. The analysis of their glyco-structures and concentration levels are increasingly important in diagnosis and proteomics. Boronic acids can covalently react with cis-diols in the oligosaccharide chains of glycoproteins to form five- or six-membered cyclic esters. Based on this interaction, boronic acid-based ligands and materials have attracted much attention in both chemistry and biology as the recognition motif for enrichment and chemo/biosensing of glycoproteins in recent years. In this work, we reviewed the progress in the separation, immobilization and detection of glycoproteins with boronic acid-functionalized materials and addressed its application in sensing.

  1. Photochemical Study of Silver Nanoparticles Formed from the Reduction of Silver Ions by Humic Acid

    Science.gov (United States)

    Leslie, Renee M.

    This study focuses on the ability of silver ions and humic acid to form silver nanoparticles in the presence of UV and visible light. Silver nanoparticles have a number of industrial applications due primarily to their antimicrobial properties, but these properties pose an environmental threat. Silver nanoparticles can directly disrupt sensitive ecosystems by harming bacteria. Consumption of silver nanoparticles results in silver ions and silver nanoparticles entering waterways; the presence of silver ions raises the question of whether nanoparticles can reform in environmental waters. As our data show, silver nanoparticles can form from the reduction of silver ions by humic acid after irradiation with UV and visible light. In order to better understand the mechanism of these naturally synthesized silver nanoparticles, we investigated the effects of reactant concentration, experimental conditions and presence of ions/reactive species. We monitored silver nanoparticle growth with UV-visible spectroscopy. The evolution in time of nanoparticle size was monitored by dynamic light scattering (DLS).

  2. Ion exchange separation of low boric acid concentrations from water

    International Nuclear Information System (INIS)

    Kysela, J.; Brabec, J.; Peterka, F.

    1975-01-01

    Boric acid poisoning of the moderator of the TR-O experimental heavy water reactor was studied. The possibility is discussed of removing boric acid from heavy water by means of a strong basic anion exchanger, below the residual concentration of 0.01 mg B/l. Measurements of the usable capacities of the strong basic anion exchanger Zerollit FF showed that the penetration of boric acid during the sorption period does not exceed the value of 0.015 mg B/l. The dependence was found of capacity on the boric acid concentration in the solution. Analytical methods used to determine B in water are also described. (author)

  3. Determination of Monochloroacetic Acid in Swimming Pool Water by Ion Chromatography-Conductivity Detection

    Directory of Open Access Journals (Sweden)

    Maria Pythias B. Espino

    2013-12-01

    Full Text Available In this study, an analytical method involving ion chromatography with conductivity detection was developed and optimized for the determination of monochloroacetic acid in swimming pool water. The ion chromatographic method has a detection limit of 0.02 mg L-1 and linear range of 0.05 to 1.0 mg L-1 with correlation coeff icient of 0.9992. The method is reproducible with percent RSD of 0.052% (n=10. The recovery of monochloroacetic acid spiked in different water types (bottled, tap and swimming pool water ranged from 28 to 122%. In dilute solutions, chloride and bromide were simultaneously analyzed along with monochloroacetic acid using the optimized method. Chloride and bromide have detection limits of 0.01 to 0.05 mg L-1, respectively. The usefulness of the ion chromatographic method was demonstrated in the analysis of monochloroacetic acid in swimming pool water samples. In such highly-chlorinated samples, an Ag/H cartridge was used prior to the ion chromatographic determination so as to minimize the signal due to chloride ion. Monochloroacetic acid was detected in concentrations between 0.020 and 0.093 mg L-1 in three of the six swimming pool water samples studied. The presence of monochloroacetic acid in the swimming pool water samples suggests the possible occurrence of other disinfection by-products in these waters.

  4. Determination of Monochloroacetic Acid in Swimming Pool Water by Ion Chromatography-Conductivity Detection

    Directory of Open Access Journals (Sweden)

    Maria Pythias B. Espino

    2013-02-01

    Full Text Available In this study, an analytical method involving ion chromatography with conductivity detection was developed and optimized for the determination of monochloroacetic acid in swimming pool water. The ion chromatographic method has a detection limit of 0.02 mg L-1 and linear range of 0.05 to 1.0 mg L-1 with correlation coeff icient of 0.9992. The method is reproducible with percent RSD of 0.052% (n=10. The recovery of monochloroacetic acid spiked in different water types (bottled, tap and swimming pool water ranged from 28 to 122%. In dilute solutions, chloride and bromide were simultaneously analyzed along with monochloroacetic acid using the optimized method. Chloride and bromide have detection limits of 0.01 to 0.05 mg L-1, respectively. The usefulness of the ion chromatographic method was demonstrated in the analysis of monochloroacetic acid in swimming pool water samples. In such highly-chlorinated samples, an Ag/H cartridge was used prior to the ion chromatographic determination so as to minimize the signal due to chloride ion. Monochloroacetic acid was detected in concentrations between 0.020 and 0.093 mg L-1 in three of the six swimming pool water samples studied. The presence of monochloroacetic acid in the swimming pool water samples suggests the possible occurrence of other disinfection by-products in these waters.

  5. A simple and selective colorimetric mercury (II) sensing system based on chitosan stabilized gold nanoparticles and 2,6-pyridinedicarboxylic acid

    International Nuclear Information System (INIS)

    Tian, Kun; Siegel, Gene; Tiwari, Ashutosh

    2017-01-01

    The development of simple and cost-effective methods for the detection and treatment of Hg 2+ in the environment is an important area of research due to the serious health risk that Hg 2+ poses to humans. Colorimetric sensing based on the induced aggregation of nanoparticles is of great interest since it offers a low cost, simple, and relatively rapid procedure, making it perfect for on-site analysis. Herein we report the development of a simple colorimetric sensor for the selective detection and estimation of mercury ions in water, based on chitosan stabilized gold nanoparticles (AuNPs) and 2,6-pyridinedicarboxylic acid (PDA). In the presence of Hg 2+ , PDA induces the aggregation of AuNPs, causing the solution to change colors varying from red to blue, depending on the concentration of Hg 2+ . The formation of aggregated AuNPs in the presence of Hg 2+ was confirmed using transmission electron microscopy (TEM) and UV–Vis spectroscopy. The method exhibits linearity in the range of 300 nM to 5 μM and shows excellent selectivity towards Hg 2+ among seventeen different metal ions and was successfully applied for the detection of Hg 2+ in spiked river water samples. The developed technique is simple and superior to the existing techniques in that it allows detection of Hg 2+ using the naked eye and simple and rapid colorimetric analysis, which eliminates the need for sophisticated instruments and sample preparation methods. - Highlights: • A simple colorimetric method for detection of Hg 2+ in water was proposed. • Au nanoparticles and 2,6-pyridinedicarboxylic acid were used for sensing Hg 2+ . • Sensing mechanisms were demonstrated by TEM and UV–Visible measurements. • It showed the solution color changes from red to blue upon addition of Hg 2+ . • The method selectively detected Hg 2+ among seventeen different metal ions.

  6. EDTA assisted synthesis of hydroxyapatite nanoparticles for electrochemical sensing of uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Kanchana, P.; Sekar, C., E-mail: Sekar2025@gmail.com

    2014-09-01

    Hydroxyapatite nanoparticles have been synthesized using EDTA as organic modifier by a simple microwave irradiation method and its application for the selective determination of uric acid (UA) has been demonstrated. Electrochemical behavior of uric acid at HA nanoparticle modified glassy carbon electrode (E-HA/GCE) has been investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and amperometry. The E-HA modified electrode exhibits efficient electrochemical activity towards uric acid sensing without requiring enzyme or electron mediator. Amperometry studies revealed that the fabricated electrode has excellent sensitivity for uric acid with the lowest detection limit of 142 nM over a wide concentration range from 1 × 10{sup −7} to 3 × 10{sup −5} M. Moreover, the studied E-HA modified GC electrode exhibits a good reproducibility and long-term stability and an admirable selectivity towards the determination of UA even in the presence of potential interferents. The analytical performance of this sensor was evaluated for the detection of uric acid in human urine and blood serum samples. - Highlights: • EDTA- hydroxyapatite (HA) nanoparticles have been synthesized by microwave irradiation method. • A novel amperometric Uric Acid biosensor has been fabricated using E-HA/GCE. • The fabricated sensor exhibits a wide linear range, good stability and high reproducibility. • The sensor was applied for the detection of UA in human blood serum and urine.

  7. EDTA assisted synthesis of hydroxyapatite nanoparticles for electrochemical sensing of uric acid

    International Nuclear Information System (INIS)

    Kanchana, P.; Sekar, C.

    2014-01-01

    Hydroxyapatite nanoparticles have been synthesized using EDTA as organic modifier by a simple microwave irradiation method and its application for the selective determination of uric acid (UA) has been demonstrated. Electrochemical behavior of uric acid at HA nanoparticle modified glassy carbon electrode (E-HA/GCE) has been investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and amperometry. The E-HA modified electrode exhibits efficient electrochemical activity towards uric acid sensing without requiring enzyme or electron mediator. Amperometry studies revealed that the fabricated electrode has excellent sensitivity for uric acid with the lowest detection limit of 142 nM over a wide concentration range from 1 × 10 −7 to 3 × 10 −5 M. Moreover, the studied E-HA modified GC electrode exhibits a good reproducibility and long-term stability and an admirable selectivity towards the determination of UA even in the presence of potential interferents. The analytical performance of this sensor was evaluated for the detection of uric acid in human urine and blood serum samples. - Highlights: • EDTA- hydroxyapatite (HA) nanoparticles have been synthesized by microwave irradiation method. • A novel amperometric Uric Acid biosensor has been fabricated using E-HA/GCE. • The fabricated sensor exhibits a wide linear range, good stability and high reproducibility. • The sensor was applied for the detection of UA in human blood serum and urine

  8. Photodegradation of bisphenol A in simulated lake water containing algae, humic acid and ferric ions

    International Nuclear Information System (INIS)

    Peng Zhang'e; Wu Feng; Deng Nansheng

    2006-01-01

    The photodegradation of bisphenol A (BPA), a suspected endocrine disruptor (ED), in simulated lake water containing algae, humic acid and Fe 3+ ions was investigated. Algae, humic acid and Fe 3+ ions enhanced the photodegradation of BPA. Photodegradation efficiency of BPA was 36% after 4 h irradiation in the presence of 6.5 x 10 9 cells L -1 raw Chlorella vulgaris, 4 mg L -1 humic acid and 20 μmol L -1 Fe 3+ . The photodegradation efficiency of BPA was higher in the presence of algae treated with ultrasonic than that without ultrasonic. The photodegradation efficiency of BPA in the water only containing algae treated with ultrasonic was 37% after 4 h irradiation. The algae treated with heating can also enhance the photodegradation of BPA. This work helps environmental scientists to understand the photochemical behavior of BPA in lake water. - Algae, humic acid and ferric ions can induce the photodegradation of bisphenol A in an aqueous environment

  9. Improved cellular response of ion modified poly(lactic acid-co-glycolic acid) substrates for mouse fibroblast cells

    Energy Technology Data Exchange (ETDEWEB)

    Adhikari, Ananta Raj, E-mail: aa8381@gmail.com [Department of Sciences, Wentworth Institute of Technology, Boston MA 02115 (United States); Geranpayeh, Tanya [Department of Biology and Biochemistry, University of Houston, Houston, TX 77204 (United States); Chu, Wei Kan [Texas Center for Superconductivity, University of Houston, Houston, TX 77204 (United States); Department of Physics, University of Houston, Houston, TX 77204 (United States); Otteson, Deborah C. [Department of Biology and Biochemistry, University of Houston, Houston, TX 77204 (United States); Department of Basic and Vision Sciences, College of Optometry, University of Houston, Houston, TX 77204 (United States)

    2016-03-01

    In this report, the effects of argon (Ar) ion irradiation on poly(lactic acid-co-glycolic acid) (PLGA) substrates on biocompatibility were studied. PLGA scaffold substrates were prepared by spin coating glass surfaces with PLGA dissolved in anhydrous chloroform. Previously, we showed that surface modifications of PLGA films using ion irradiation modulate the inherent hydrophobicity of PLGA surface. Here we show that with increasing ion dose (1 × 10{sup 12} to 1 × 10{sup 14} ions/cm{sup 2}), hydrophobicity and surface roughness decreased. Biocompatibility for NIH3T3 mouse fibroblast cells was increased by argon irradiation of PLGA substrates. On unirradiated PLGA films, fibroblasts had a longer doubling time and cell densities were 52% lower than controls after 48 h in vitro. Argon irradiated PLGA substrates supported growth rates similar to control. Despite differences in cell cycle kinetics, there was no detectible cytotoxicity observed on any substrate. This demonstrates that argon ion irradiation can be used to tune the surface microstructure and generate substrates that are more compatible for the cell growth and proliferation. - Highlights: • Argon irradiation modifies surface chemistry and increases hydrophilicity of poly(lactic-glycolic) acid (PLGA) films. • Both native and irradiated PLGA films were not cytotoxic for mouse fibroblasts. • Fibroblast proliferation increased on PLGA substrates modified with higher doses of Argon irradiation. • Surface modification with Argon irradiation increases biocompatibility of PLGA films.

  10. Improved cellular response of ion modified poly(lactic acid-co-glycolic acid) substrates for mouse fibroblast cells

    International Nuclear Information System (INIS)

    Adhikari, Ananta Raj; Geranpayeh, Tanya; Chu, Wei Kan; Otteson, Deborah C.

    2016-01-01

    In this report, the effects of argon (Ar) ion irradiation on poly(lactic acid-co-glycolic acid) (PLGA) substrates on biocompatibility were studied. PLGA scaffold substrates were prepared by spin coating glass surfaces with PLGA dissolved in anhydrous chloroform. Previously, we showed that surface modifications of PLGA films using ion irradiation modulate the inherent hydrophobicity of PLGA surface. Here we show that with increasing ion dose (1 × 10 12 to 1 × 10 14 ions/cm 2 ), hydrophobicity and surface roughness decreased. Biocompatibility for NIH3T3 mouse fibroblast cells was increased by argon irradiation of PLGA substrates. On unirradiated PLGA films, fibroblasts had a longer doubling time and cell densities were 52% lower than controls after 48 h in vitro. Argon irradiated PLGA substrates supported growth rates similar to control. Despite differences in cell cycle kinetics, there was no detectible cytotoxicity observed on any substrate. This demonstrates that argon ion irradiation can be used to tune the surface microstructure and generate substrates that are more compatible for the cell growth and proliferation. - Highlights: • Argon irradiation modifies surface chemistry and increases hydrophilicity of poly(lactic-glycolic) acid (PLGA) films. • Both native and irradiated PLGA films were not cytotoxic for mouse fibroblasts. • Fibroblast proliferation increased on PLGA substrates modified with higher doses of Argon irradiation. • Surface modification with Argon irradiation increases biocompatibility of PLGA films.

  11. Halogeno-substituted 2-aminobenzoic acid derivatives for negative ion fragmentation studies of N-linked carbohydrates.

    Science.gov (United States)

    Harvey, David J

    2005-01-01

    Negative ion electrospray mass spectra of high-mannose N-linked glycans derivatised with 2-aminobenzoic acids and ionised from solutions containing ammonium hydroxide gave prominent [M-H](-) ions accompanied by weaker [M-2H](2-) ions. Fragmentation of both types of ions gave prominent singly charged glycosidic cleavage ions containing the derivatised reducing terminus and ions from the non-reducing terminus that appeared to be products of cross-ring cleavages. Differentiation of these two groups of ions was conveniently achieved in a single spectrum by use of chloro- or bromo-substituted benzoic acids in order to label ions containing the derivative with an atom with a distinctive isotope pattern. Fragmentation of the doubly charged ions gave more abundant fragments, both singly and doubly charged, than did fragmentation of the singly charged ions, but information of chain branching was masked by the appearance of prominent ions produced by internal cleavages. Copyright (c) 2005 John Wiley & Sons, Ltd.

  12. Polyamine/salt-assembled microspheres coated with hyaluronic acid for targeting and pH sensing.

    Science.gov (United States)

    Zhang, Pan; Yang, Hui; Wang, Guojun; Tong, Weijun; Gao, Changyou

    2016-06-01

    The poly(allylamine hydrochloride)/trisodium citrate aggregates were fabricated and further covalently crosslinked via the coupling reaction of carboxylic sites on trisodium citrate with the amine groups on polyamine, onto which poly-L-lysine and hyaluronic acid were sequentially assembled, forming stable microspheres. The pH sensitive dye and pH insensitive dye were further labeled to enable the microspheres with pH sensing property. Moreover, these microspheres could be specifically targeted to HeLa tumor cells, since hyaluronic acid can specifically recognize and bind to CD44, a receptor overexpressed on many tumor cells. Quantitative pH measurement by confocal laser scanning microscopy demonstrated that the microspheres were internalized into HeLa cells, and accumulated in acidic compartments. By contrast, only a few microspheres were adhered on the NIH 3T3 cells surface. The microspheres with combined pH sensing property and targeting ability can enhance the insight understanding of the targeted drug vehicles trafficking after cellular internalization. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Ammonia Gas Sensing Behavior of Tanninsulfonic Acid Doped Polyaniline-TiO2 Composite

    Directory of Open Access Journals (Sweden)

    Venu Gopal Bairi

    2015-10-01

    Full Text Available A highly active tannin doped polyaniline-TiO2 composite ammonia gas sensor was developed and the mechanism behind the gas sensing activity was reported for the first time. A tanninsulfonic acid doped polyaniline (TANIPANI-titanium dioxide nanocomposite was synthesized by an in situ polymerization of aniline in the presence of tanninsulfonic acid and titanium dioxide nanoparticles. X-ray diffraction and thermogravimetric analysis were utilized to determine the incorporation of TiO2 in TANIPANI matrix. UV-Visible and infrared spectroscopy studies provided information about the electronic interactions among tannin, polyaniline, and TiO2. Scanning electron microscopy (SEM along with energy dispersive X-ray spectroscopy (EDS and atomic force microscopy (AFM surface analysis techniques were used to investigate the metal oxide dispersions inside polyaniline matrix. Gas sensors were prepared by spin coating solutions of TANIPANI-TiO2 and TANIPANI composites onto glass slides. Sensors were tested at three different concentrations (20 ppm, 40 ppm, and 60 ppm of ammonia gas at ambient temperature conditions by measuring the changes in surface resistivity of the films with respect to time. Ammonia gas sensing plots are presented showing the response values, response times and recovery times. The TANIPANI-TiO2 composite exhibited better response and shorter recovery times when compared to TANIPANI control and other polyaniline composites that have been reported in the literature. For the first time a proposed mechanism of gas sensing basing on the polaron band localization and its effects on the gas sensing behavior of polyaniline are reported.

  14. Cation-Size-Dependent Conformational Locking of Glutamic Acid by Alkali Ions: Infrared Photodissociation Spectroscopy of Cryogenic Ions.

    Science.gov (United States)

    Klyne, Johanna; Bouchet, Aude; Ishiuchi, Shun-Ichi; Fujii, Masaaki; Dopfer, Otto

    2018-03-01

    Consolidated knowledge of conformation and stability of amino acids and their clusters is required to understand their biochemical recognition. Often, alkali ions interact with amino acids and proteins. Herein, infrared photodissociation (IRPD) spectra of cryogenic metalated glutamic acid ions (GluM + , M = Li-Cs) are systematically analyzed in the isomer-specific fingerprint and XH stretch ranges (1100-1900, 2600-3600 cm -1 ) to provide a direct measure for cation-size-dependent conformational locking. GluM + ions are generated by electrospray ionization and cooled down to 15 K in a cryogenic quadrupole ion trap. The assignment of the IRPD spectra is supported by density functional theory calculations at the dispersion-corrected B3LYP-D3/aug-cc-pVTZ level. In the global minimum of GluM + , the flexibility of Glu is strongly reduced by the formation of rigid ionic CO···M + ···OC metal bridges, corresponding to charge solvation. The M + binding energy decreases monotonically with increasing cation size from D 0 = 314 to 119 kJ/mol for Li-Cs. Whereas for Li and Na only the global minimum of GluM + is observed, for K-Cs at least three isomers exist at cryogenic temperature. The IRPD spectra of cold GluM + ions are compared to IR multiple-photon dissociation spectra measured at room temperature. Furthermore, we elucidate the differences of the impact of protonation and metalation on the structure and conformational locking of Glu.

  15. Ferric ion mediated photochemical decomposition of perfluorooctanoic acid (PFOA) by 254 nm UV light

    International Nuclear Information System (INIS)

    Wang Yuan; Zhang Pengyi; Pan Gang; Chen Hao

    2008-01-01

    The great enhancement of ferric ion on the photochemical decomposition of environmentally persistent perfluorooctanoic acid (PFOA) under 254 nm UV light was reported. In the presence of 10 μM ferric ion, 47.3% of initial PFOA (48 μM) was decomposed and the defluorination ratio reached 15.4% within 4 h reaction time. While the degradation and defluorination ratio greatly increased to 80.2% and 47.8%, respectively, when ferric ion concentration increased to 80 μM, and the corresponding half-life was shortened to 103 min. Though the decomposition rate was significantly lowered under nitrogen atmosphere, PFOA was efficiently decomposed too. Other metal ions like Cu 2+ and Zn 2+ also slightly improved the photochemical decomposition of PFOA under irradiation of 254 nm UV light. Besides fluoride ion, other intermediates during PFOA decomposition including formic acid and five shorter-chain perfluorinated carboxylic acids (PFCAs) with C7, C6, C5, C4 and C3, respectively, were identified and quantified by IC or LC/MS. The mixture of PFOA and ferric ion had strong absorption around 280 nm. It is proposed that PFOA coordinates with ferric ion to form a complex, and its excitation by 254 nm UV light leads to the decomposition of PFOA in a stepwise way

  16. Label-free tungsten disulfide quantum dots as a fluorescent sensing platform for highly efficient detection of copper (II) ions

    International Nuclear Information System (INIS)

    Zhao Xuan; He Da-Wei; Wang Yong-Sheng; Hu Yin; Fu Chen; Li Xue

    2017-01-01

    A fluorescent probe for the sensitive and selective determination of copper ion (Cu 2+ ) is presented. It is based on the use of tungsten disulfide quantum dots (WS 2 QDs) which is independent of the pH of solution and emits strong blue fluorescence. Copper ions could cause aggregation of the WS 2 QDs and lead to fluorescence quenching of WS 2 QDs. The change of fluorescence intensity is proportional to the concentration of Cu 2+ , and the limit of detection is 0.4 μM. The fluorescent probe is highly selective for Cu 2+ over some potentially interfering ions. These results indicate that WS 2 QDs, as a fluorescent sensing platform, can meet the selective requirements for biomedical and environmental application. (paper)

  17. Zinc-ion-dependent acid phosphatase exhibits magnesium-ion-dependent myo-inositol-1-phosphatase activity.

    Science.gov (United States)

    Fujimoto, S; Okano, I; Tanaka, Y; Sumida, Y; Tsuda, J; Kawakami, N; Shimohama, S

    1996-06-01

    We have purified bovine brain Zn(2+)-dependent acid phosphatase (Zn(2+)-APase), which requires Zn2+ ions to hydrolyze the substrate p-nitrophenyl phosphate (pNPP) in an acidic environment. The substrate specificity and metal requirement of Zn(2+)-APase at a physiological pH was also studied. The enzyme exhibited hydrolytic activity on myo-inositol-1- and -2-monophosphates, 2'-adenosine monophosphate, 2'-guanosine monophosphate, and the alpha- and beta-glycerophosphates, glucose-1-phosphate, and fructose-6-phosphate in 50 mM Tris-HCl buffer (pH 7.4) in the presence of Mg2+ ions, but not on pNPP and phosphotyrosine. Zn2+, Mn2+ and Co2+ ions were less effective for activation. Among the above substrates, myo-inositol-1-phosphate was the most susceptible to hydrolysis by the enzyme in the presence of 3 mM Mg2+ ions. The enzyme exhibited an optimum pH at around 8 for myo-inositol-1-phosphate in the presence of 3 mM Mg2+ ions. The Mg(2+)-dependent myo-inositol-1-phosphatase activity of the enzyme was significantly inhibited by Li+ ions. The Zn(2+)-dependent p-nitrophenyl phosphatase activity and Mg(2+)-dependent myo-inositol-1-phosphatase activity of the purified enzyme fraction exhibited similar behavior on Sephadex G-100 and Mono Q colomns. These findings suggest that Zn(2+)-APase also exhibits Mg(2+)-dependent myo-inositol-1-phosphatase activity under physiological conditions.

  18. Separation of ions in acidic solution by capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, Michelle [Iowa State Univ., Ames, IA (United States)

    1997-10-08

    Capillary electrophoresis (CE) is an effective method for separating ionic species according to differences in their electrophoretic mobilities. CE separations of amino acids by direct detection are difficult due to their similar electrophoretic mobilities and low absorbances. However, native amino acids can be separated by CE as cations at a low pH by adding an alkanesulfonic acid to the electrolyte carrier which imparts selectivity to the system. Derivatization is unnecessary when direct UV detection is used at 185 nm. Simultaneous speciation of metal cations such as vanadium (IV) and vanadium (V) can easily be performed without complexation prior to analysis. An indirect UV detection scheme for acidic conditions was also developed using guanidine as the background carrier electrolyte (BCE) for the indirect detection of metal cations. Three chapters have been removed for separate processing. This report contains introductory material, references, and general conclusions. 80 refs.

  19. Acidic pH sensing in the bacterial cytoplasm is required for Salmonella virulence.

    Science.gov (United States)

    Choi, Jeongjoon; Groisman, Eduardo A

    2016-09-01

    pH regulates gene expression, biochemical activities and cellular behaviors. A mildly acidic pH activates the master virulence regulatory system PhoP/PhoQ in the facultative intracellular pathogen Salmonella enterica serovar Typhimurium. The sensor PhoQ harbors an extracytoplasmic domain implicated in signal sensing, and a cytoplasmic domain controlling activation of the regulator PhoP. We now report that, surprisingly, a decrease in Salmonella's own cytoplasmic pH induces transcription of PhoP-activated genes even when the extracytoplasmic pH remains neutral. Amino acid substitutions in PhoQ's cytoplasmic domain hindered activation by acidic pH and attenuated virulence in mice, but did not abolish activation by low Mg(2+) or the antimicrobial peptide C18G. Conversely, removal of PhoQ's extracytoplasmic domains prevented the response to the latter PhoQ-activating signals but not to acidic pH. PhoP-dependent genes were minimally induced by acidic pH in the non-pathogenic species Salmonella bongori but were activated by low Mg(2+) and C18G as in pathogenic S. enterica. Our findings indicate that the sensor PhoQ enables S. enterica to respond to both host- and bacterial-derived signals that alter its cytoplasmic pH. © 2016 John Wiley & Sons Ltd.

  20. EDTA assisted synthesis of hydroxyapatite nanoparticles for electrochemical sensing of uric acid.

    Science.gov (United States)

    Kanchana, P; Sekar, C

    2014-09-01

    Hydroxyapatite nanoparticles have been synthesized using EDTA as organic modifier by a simple microwave irradiation method and its application for the selective determination of uric acid (UA) has been demonstrated. Electrochemical behavior of uric acid at HA nanoparticle modified glassy carbon electrode (E-HA/GCE) has been investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and amperometry. The E-HA modified electrode exhibits efficient electrochemical activity towards uric acid sensing without requiring enzyme or electron mediator. Amperometry studies revealed that the fabricated electrode has excellent sensitivity for uric acid with the lowest detection limit of 142 nM over a wide concentration range from 1 × 10(-7) to 3 × 10(-5)M. Moreover, the studied E-HA modified GC electrode exhibits a good reproducibility and long-term stability and an admirable selectivity towards the determination of UA even in the presence of potential interferents. The analytical performance of this sensor was evaluated for the detection of uric acid in human urine and blood serum samples. Copyright © 2014. Published by Elsevier B.V.

  1. Reporter-free potentiometric sensing of boronic acids and their reactions by using quaternary ammonium salt-functionalized polymeric liquid membranes.

    Science.gov (United States)

    Wang, Xuewei; Yue, Dengfeng; Lv, Enguang; Wu, Lei; Qin, Wei

    2014-02-18

    The tremendous applications of boronic acids (BAs) in chemical sensing, medical chemistry, molecular assembly, and organic synthesis lead to an urgent demand for developing effective sensing methods for BAs. This paper reports a facile and sensitive potentiometric sensor scheme for heterogeneous detection of BAs based on their unexpected potential responses on quaternary ammonium salt-doped polymeric liquid membranes. (11)B NMR data reveal that a quaternary ammonium chloride can trigger the hydrolysis of an electrically neutral BA in an aprotic solvent. Using the quaternary ammonium salt as the receptor, the BA molecules can be extracted from the sample solution into the polymeric membrane phase and undergo the concomitant hydrolysis. Such salt-triggered hydrolysis generates H(+) ions, which can be coejected into the aqueous phase with the counterions (e.g., Cl(-)) owing to their high hydrophilicities. The perturbation on the ionic partition at the sample-membrane interface changes the phase boundary potential and thus enables the potentiometric sensing of BAs. In contrast to other transduction methods for BAs, for which labeled or separate reporters are exclusively required, the present heterogeneous sensing scheme allows the direct detection of BAs without using any reporter molecules. This technique shows superior detection limits for BAs (e.g., 1.0 × 10(-6) M for phenylboronic acid) as compared to previously reported methods based on colorimetry, fluorimetry, and mass spectrometry. The proposed sensing strategy has also been successfully applied to potentiometric indication of the BA reactions with hydrogen peroxide and saccharides, which allows indirect and sensitive detection of these important species.

  2. Preparation and adsorption behavior for metal ions and humic acid of chitosan derivatives crosslinked by irradiation

    International Nuclear Information System (INIS)

    Zhao Long; Wasikiewicz, J.M.; Mitomo, H.; Nagasawa, N.; Yoshii, F.

    2007-01-01

    This article deals with the determination of the adsorption properties of metal ions and humic acid in wa- ter on crosslinked chitosan derivatives (carboxymethylchitosan) which were formed using the irradiation technique without any additives. The solubility test of these crosslinked materials were investigated in acidic, alkaline media, distilled water, and certain organic solvents. Scanning electron microscopic (SEM) images showed that the crosslinked chitosan derivatives possessed a porous morphological structure. Charged characteristic analyses demonstrated typically pH-dependent properties of the crosslinked materials. The adsorption studies were carded out by the batch method at room temperature. Adsorption of heavy metal ions (such as Cu 2+ , Cd 2+ ) and humic acid onto crosslinked samples was found to be strongly pH-dependent. Adsorption kinetic studies indicated the rapid removal of metal ions, and humic acid from the aqueous solutions. Moreover, isothermal adsorption data revealed that Cu 2+ , Cd 2+ , and humic acid were removed by these crosslinked materials with high efficiency. Adsorption isothermal data were interpreted well by the Langmuir equation. These crosslinked carboxymethylated chitosan derivatives indicate favorable adsorption of metal ions and humic acid. (authors)

  3. A phenolic acid based colourimetric 'naked-eye' chemosensor for the rapid detection of Cu(II) ions

    Science.gov (United States)

    Sengupta, Priti; Ganguly, Aniruddha; Bose, Adity

    2018-06-01

    The crucial role of chemosensor for the immediate recognition of environment pollutant motivates the researchers to develop variety of sensing protocols. Of various chemosensory protocols, the colour change observed by the naked eye is considered to be a conceivable and on-site way to indicate the presence of an analyte. We herein report a colourimetric and commercially available absorption probe, sinapic acid (SA) that is completely ready to use for "on-site" visual determination of copper ions. The molecule, SA is well-known phenolic acid, often utilized for its antibacterial activity. In this work, for the first time, we are exploring its ability to work as an efficient Cu2+ sensor. This sensor molecule selectively detected Cu2+ ions by changing its colour from colourless to pink within detection limit of 64.5 nM, which is much lower than other reported sensor molecules and the suggested limit by World Health Organization (WHO) and U. S. Environmental Protection Agency (EPA) guidelines. The sensing mechanism was investigated through UV-vis and 1H NMR titration along with ESI-MS spectroscopy and further confirmed by DFT computational studies. Studies revealed the participation of hydroxyl group (sbnd OH) and methoxy group (sbnd OMe) of SA in complexation with Cu2+. The binding stoichiometry of SA to Cu2+ was found to be 1:2 through Job's plot and ESI-MS analysis. Importantly, paper strips of SA were prepared which could be used for a rapid "on-site" determination of Cu2+ containing samples.

  4. Ratiometric Sensing of Hydrogen Peroxide Utilizing Conformational Change in Fluorescent Boronic Acid Polymers

    Directory of Open Access Journals (Sweden)

    Kan Takeshima

    2017-01-01

    Full Text Available We demonstrate that the copolymers containing boronic acid and pyrene units can be utilized for the fluorometric sensing of hydrogen peroxide (H2O2 in aqueous solutions. The copolymer exists in a relatively extended conformation in the absence of H2O2, whereas the polymer chain is contracted by the reaction of boronic acid moieties with H2O2 to form phenol groups. This conformational change induces aggregation of the originally isolated pyrene groups. As a result, relative intensity of excimer emission with respect to monomer emission increases with H2O2 concentration. Accordingly, the present methodology enables us to measure H2O2 by means of ratiometric fluorescence change in the range of 0–30 μM.

  5. Targeting GPR120 and other fatty acid sensing GPCRs ameliorates insulin resistance and inflammatory diseases

    Science.gov (United States)

    Talukdar, Saswata; Olefsky, Jerrold M; Osborn, Olivia

    2011-01-01

    The last decade has seen great progress in the understanding of the molecular pharmacology, physiological function and therapeutic potential of the G protein-coupled receptors. Free Fatty acids (FFAs) have been demonstrated to act as ligands of several GPCRs including GPR40, GPR43, GPR84, GPR119 and GPR120. We have recently shown that GPR120 acts as a physiological receptor of ω3 fatty acids in macrophages and adipocytes, which mediate potent anti-inflammatory and insulin sensitizing effects. The important role GPR120 plays in the control of inflammation raises the possibility that targeting this receptor could have therapeutic potential in many inflammatory diseases including obesity and type 2 diabetes. In this review, we discuss lipid-sensing GPCRs and highlight potential outcomes of targeting such receptors in ameliorating disease. PMID:21663979

  6. Targeting GPR120 and other fatty acid-sensing GPCRs ameliorates insulin resistance and inflammatory diseases.

    Science.gov (United States)

    Talukdar, Saswata; Olefsky, Jerrold M; Osborn, Olivia

    2011-09-01

    The past decade has seen great progress in the understanding of the molecular pharmacology, physiological function and therapeutic potential of G-protein-coupled receptors (GPCRs). Free fatty acids (FFAs) have been demonstrated to act as ligands of several GPCRs including GPR40, GPR43, GPR84, GPR119 and GPR120. We have recently shown that GPR120 acts as a physiological receptor of ω3 fatty acids in macrophages and adipocytes, which mediate potent anti-inflammatory and insulin sensitizing effects. The important role GPR120 plays in the control of inflammation raises the possibility that targeting this receptor could have therapeutic potential in many inflammatory diseases including obesity and type 2 diabetes. In this review paper, we discuss lipid-sensing GPCRs and highlight potential outcomes of targeting such receptors in ameliorating disease. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Single-column ion chromatography with determination of hydrazoic acid produced in spent nuclear fuel reprocessing

    International Nuclear Information System (INIS)

    Ma Guilan; Tan Shuping

    2006-01-01

    The reaction of hydrazine and its derivative with ammonium metavanadate may produce hydrazoic acid (HN 3 ). A single-column ion chromatography is used for the determination of HN 3 after neutralizing the rest acid in the sample with sodium hydroxide. Chromatography separation of HN 3 is carried out on a 25 cm x 0.46 cm (inside diameter) stainless steel column packed with Vydac IC302 ion Chromatography packing. The eluent is 1 mmol/L o-phthalic acid, and the ion is detected by conductivity detector. The detection limit in the presence chromatography is 5 μg/mL, the linear range is from 5 to 201 μg/mL, the linear correlation coefficient is 0.9994, respectively. The analysis accuracy is 2% for standard sample, and the detection limit is 51 μg/mL for HN 3 in the real sample. (authors)

  8. The inhibitory effect of metals and other ions on acid phosphatase activity from Vigna aconitifolia seeds.

    Science.gov (United States)

    Srivastava, Pramod Kumar; Anand, Asha

    2015-01-01

    Sensitivity of acid phosphatase from Vigna aconitifolia seeds to metal ions, fluoride, and phosphate was examined. All the effectors had different degree of inhibitory effect on the enzyme. Among metal ions, molybdate and ferric ion were observed to be most potent inhibitors and both exhibited mixed type of inhibition. Acid phosphatase activity was inhibited by Cu2+ in a noncompetitive manner. Zn and Mn showed mild inhibition on the enzyme activity. Inhibition kinetics analysis explored molybdate as a potent inhibitor for acid phosphatase in comparison with other effectors used in this study. Fluoride was the next most strong inhibitor for the enzyme activity, and caused a mixed type of inhibition. Phosphate inhibited the enzyme competitively, which demonstrates that inhibition due to phosphate is one of the regulatory factors for enzyme activity.

  9. Electrochemical membrane reactor: In situ separation and recovery of chromic acid and metal ions

    International Nuclear Information System (INIS)

    Khan, Jeeshan; Tripathi, Bijay P.; Saxena, Arunima; Shahi, Vinod K.

    2007-01-01

    An electrochemical membrane reactor with three compartments (anolyte, catholyte and central compartment) based on in-house-prepared cation- and anion-exchange membrane was developed to achieve in situ separation and recovery of chromic acid and metal ions. The physicochemical and electrochemical properties of the ion-exchange membrane under standard operating conditions reveal its suitability for the proposed reactor. Experiments using synthetic solutions of chromate and dichromate of different concentrations were carried out to study the feasibility of the process. Electrochemical reactions occurring at the cathode and anode under operating conditions are proposed. It was observed that metal ion migrated through the cation-exchange membrane from central compartment to catholyte and OH - formation at the cathode leads to the formation of metal hydroxide. Simultaneously, chromate ion migrated through the anion-exchange membrane from central compartment to the anolyte and formed chromic acid by combining H + produced their by oxidative water splitting. Thus a continuous decay in the concentration of chromate and metal ion was observed in the central compartment, which was recovered separately in the anolyte and catholyte, respectively, from their mixed solution. This process was completely optimized in terms of operating conditions such as initial concentration of chromate and metal ions in the central compartment, the applied cell voltage, chromate and metal ion flux, recovery percentage, energy consumption, and current efficiency. It was concluded that chromic acid and metal ions can be recovered efficiently from their mixed solution leaving behind the uncharged organics and can be reused as their corresponding acid and base apart from the purifying water for further applications

  10. Advances in silver ion chromatography for the analysis of fatty acids and triacylglycerols-2001 to 2011.

    Science.gov (United States)

    Momchilova, Svetlana M; Nikolova-Damyanova, Boryana M

    2012-01-01

    An effort is made to critically present the achievements in silver ion chromatography during the last decade. Novelties in columns, mobile-phase compositions and detectors are described. Recent applications of silver ion chromatography in the analysis of fatty acids and triacylglycerols are presented while stressing novel analytical strategies or new objects. The tendencies in the application of the method in complementary ways with reversed-phase chromatography, chiral chromatography and, especially, mass detection are outlined.

  11. ANTS-anchored Zn-Al-CO3-LDH particles as fluorescent probe for sensing of folic acid

    International Nuclear Information System (INIS)

    Liu, Pengfei; Liu, Dan; Liu, Yanhuan; Li, Lei

    2016-01-01

    A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO 3 -layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn 2+ ions of Zn-Al-CO 3 -LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO 3 -LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO 3 -LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO 3 groups in ANTS-anchored on the surface of Zn-Al-CO 3 -LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO 3 -LDH particles can afford a very sensitive system for the sensing FA in aqueous solution. - Highlights: • A novel fluorescent nanosensor has been developed. • The sensor exhibited highly sensitive and selective response to FA. • The fluorescence quenching was fitted to Stern–Volmer equation. • The linear response range was 1–200 μM with a limit of detection of 0.1 μM.

  12. Hard and soft acids and bases: atoms and atomic ions.

    Science.gov (United States)

    Reed, James L

    2008-07-07

    The structural origin of hard-soft behavior in atomic acids and bases has been explored using a simple orbital model. The Pearson principle of hard and soft acids and bases has been taken to be the defining statement about hard-soft behavior and as a definition of chemical hardness. There are a number of conditions that are imposed on any candidate structure and associated property by the Pearson principle, which have been exploited. The Pearson principle itself has been used to generate a thermodynamically based scale of relative hardness and softness for acids and bases (operational chemical hardness), and a modified Slater model has been used to discern the electronic origin of hard-soft behavior. Whereas chemical hardness is a chemical property of an acid or base and the operational chemical hardness is an experimental measure of it, the absolute hardness is a physical property of an atom or molecule. A critical examination of chemical hardness, which has been based on a more rigorous application of the Pearson principle and the availability of quantitative measures of chemical hardness, suggests that the origin of hard-soft behavior for both acids and bases resides in the relaxation of the electrons not undergoing transfer during the acid-base interaction. Furthermore, the results suggest that the absolute hardness should not be taken as synonymous with chemical hardness but that the relationship is somewhat more complex. Finally, this work provides additional groundwork for a better understanding of chemical hardness that will inform the understanding of hardness in molecules.

  13. POLY(AMINOMETHYLENEPHOSPHONIC ACID FOR SOLVENT EXTRACTION OF METAL IONS

    Directory of Open Access Journals (Sweden)

    M’hamed Kaid

    2011-09-01

    Full Text Available Diaminododecyltetramethylenetetraphosphonic acid (DADTMTPA has been investigated in liquid - liquid extraction of Zn (II and Cu (II in acetate media. The extraction of both cations was carried out in different media with the addition of CH3COONa, CH3COOH, HCl and H2SO4 at different pH values. The maximum extraction yield for copper is 70% after addition of 10 mg of sodium acetate and for zinc is 30% after addition of acetic acid at pHi = 5.5, in one step.

  14. Elucidating the role of ferrous ion cocatalyst in enhancing dilute acid pretreatment of lignocellulosic biomass

    Directory of Open Access Journals (Sweden)

    Wei Hui

    2011-11-01

    Full Text Available Abstract Background Recently developed iron cocatalyst enhancement of dilute acid pretreatment of biomass is a promising approach for enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known about the underlying mechanisms of this enhancement. In the current study, our aim was to identify several essential factors that contribute to ferrous ion-enhanced efficiency during dilute acid pretreatment of biomass and to initiate the investigation of the mechanisms that result in this enhancement. Results During dilute acid and ferrous ion cocatalyst pretreatments, we observed concomitant increases in solubilized sugars in the hydrolysate and reducing sugars in the (insoluble biomass residues. We also observed enhancements in sugar release during subsequent enzymatic saccharification of iron cocatalyst-pretreated biomass. Fourier transform Raman spectroscopy showed that major peaks representing the C-O-C and C-H bonds in cellulose are significantly attenuated by iron cocatalyst pretreatment. Imaging using Prussian blue staining indicated that Fe2+ ions associate with both cellulose/xylan and lignin in untreated as well as dilute acid/Fe2+ ion-pretreated corn stover samples. Analyses by scanning electron microscopy and transmission electron microscopy revealed structural details of biomass after dilute acid/Fe2+ ion pretreatment, in which delamination and fibrillation of the cell wall were observed. Conclusions By using this multimodal approach, we have revealed that (1 acid-ferrous ion-assisted pretreatment increases solubilization and enzymatic digestion of both cellulose and xylan to monomers and (2 this pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C-O-C and C-H bonds in cellulose.

  15. Selective Liquid-Liquid Extraction of Lead Ions Using Newly Synthesized Extractant 2-(Dibutylcarbamoylbenzoic Acid

    Directory of Open Access Journals (Sweden)

    Hossein Soltani

    2015-12-01

    Full Text Available A new carboxylic acid extractant, named 2-(dibutylcarbamoylbenzoic acid, is prepared and its potential for selective solvent extraction and recovery of lead ions from industrial samples was investigated. The slope analysis indicated that the lead ions are extracted by formation of 1:2 metal to ligand complexes. The effect of the parameters influencing the extraction efficiency including kind of the organic diluent, extractant concentration, type of the salt used for ionic strength adjustment, contact time and temperature was evaluated and discussed. Under optimized conditions (aqueous phase: 5 ml, initial lead concentration 1 × 10-4 M, pH 4, sodium chloride 0.1 M; organic phase: 5 ml dichloromethane, ligand concentration 0.05 M, a quantitative (75.2 ± 0.8% and highly selective extraction of lead ions in the presence of zinc, nickel, cobalt and cadmium ions (each 1 × 10-4 M was achieved, after 20 min. magnetically stirring of the phases, at      25 °C. The extracted lead ions were stripped from the organic phase by diluted nitric acid (0.1 M solution. The proposed method was successfully applied for separation of lead from industrial samples. The study of the effect of temperature allowed evaluating the thermodynamic parameters of the extraction process of lead ions by the studied extractant into dichloromethane.

  16. Depression Mechanism of Strontium Ions in Bastnaesite Flotation with Salicylhydroxamic Acid as Collector

    Directory of Open Access Journals (Sweden)

    Shiming Cao

    2018-02-01

    Full Text Available Metal ions are widely present in flotation pulp. Metal ions change solution chemistry and mineral surface properties, consequently affecting mineral flotation. In this work, the effect of strontium ions on bastnaesite flotation with salicylhydroxamic acid (SHA was investigated by microflotation tests, contact angle measurements, zeta-potential measurements, and X-ray photoelectron spectroscopy (XPS analysis. Microflotation tests confirmed that the addition of strontium ions decreased bastnaesite floatability, compared with that in the absence of strontium ions. Contact angle measurements suggested that the pretreatment of strontium ions decreased SHA adsorption. Zeta potential measurements confirmed that the bastnaesite was depressed by the adsorption of positively charged strontium species, and the lower adsorption capacity of SHA onto the bastnaesite surfaces was obtained after modifying with strontium ions. XPS analysis demonstrated that strontium ions adsorbed onto the bastnaesite surfaces through the interaction between strontium ions and oxygen atoms of surface ≡ CeOH 0 groups. This occurrence hindered surface Ce sites which chelated with SHA and therefore, decreased bastnaesite floatability.

  17. Regulation of hypothalamic neuronal sensing and food intake by ketone bodies and fatty acids.

    Science.gov (United States)

    Le Foll, Christelle; Dunn-Meynell, Ambrose A; Miziorko, Henri M; Levin, Barry E

    2014-04-01

    Metabolic sensing neurons in the ventromedial hypothalamus (VMH) alter their activity when ambient levels of metabolic substrates, such as glucose and fatty acids (FA), change. To assess the relationship between a high-fat diet (HFD; 60%) intake on feeding and serum and VMH FA levels, rats were trained to eat a low-fat diet (LFD; 13.5%) or an HFD in 3 h/day and were monitored with VMH FA microdialysis. Despite having higher serum levels, HFD rats had lower VMH FA levels but ate less from 3 to 6 h of refeeding than did LFD rats. However, VMH β-hydroxybutyrate (β-OHB) and VMH-to-serum β-OHB ratio levels were higher in HFD rats during the first 1 h of refeeding, suggesting that VMH astrocyte ketone production mediated their reduced intake. In fact, using calcium imaging in dissociated VMH neurons showed that ketone bodies overrode normal FA sensing, primarily by exciting neurons that were activated or inhibited by oleic acid. Importantly, bilateral inhibition of VMH ketone production with a 3-hydroxy-3-methylglutaryl-CoA synthase inhibitor reversed the 3- to 6-h HFD-induced inhibition of intake but had no effect in LFD-fed rats. These data suggest that a restricted HFD intake regimen inhibits caloric intake as a consequence of FA-induced VMH ketone body production by astrocytes.

  18. Using polyatomic primary ions to probe an amino acid and a nucleic base in water ice

    Energy Technology Data Exchange (ETDEWEB)

    Conlan, X.A. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)]. E-mail: x.conlan@postgrad.manchester.ac.uk; Biddulph, G.X. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)]. E-mail: G.Biddulph@postgrad.manchester.ac.uk; Lockyer, N.P. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom); Vickerman, J.C. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)]. E-mail: John.Vickerman@manchester.ac.uk

    2006-07-30

    In this study on pure water ice, we show that protonated water species [H{sub 2}O] {sub n}H{sup +} are more prevalent than (H{sub 2}O) {sub n} {sup +} ions after bombardment by Au{sup +} monoatomic and Au{sub 3} {sup +} and C{sub 60} {sup +} polyatomic projectiles. This data also reveals significant differences in water cluster yields under bombardment by these three projectiles. The amino acid alanine and the nucleic base adenine in solution have been studied and have been shown to have an effect on the water cluster ion yields observed using an Au{sub 3} {sup +} ion beam.

  19. Gadolinium(III) ion selective sensor using a new synthesized Schiff's base as a sensing material

    Energy Technology Data Exchange (ETDEWEB)

    Zamani, Hassan Ali, E-mail: haszamani@yahoo.com [Department of Applied Chemistry, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Mohammadhosseini, Majid [Department of Chemistry, Faculty of Basic Sciences, Shahrood Branch, Islamic Azad University, Shahrood (Iran, Islamic Republic of); Haji-Mohammadrezazadeh, Saeed [Department of Chemistry, Payame Noor University, Ardakan (Iran, Islamic Republic of); Faridbod, Farnoush [Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Ganjali, Mohammad Reza [Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Meghdadi, Soraia [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Davoodnia, Abolghasem [Department of Chemistry, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of)

    2012-05-01

    According to a solution study which showed a selective complexation between N,N Prime -bis(methylsalicylidene)-2-aminobenzylamine (MSAB) and gadolinium ions, MSAB was used as a sensing element in construction of a gadolinium(III) ion selective electrode. Acetophenon (AP) was used as solvent mediator and sodium tetraphenyl borate (NaTPB) as an anion excluder. The electrode showed a good selectivity towards Gd(III) ions over a wide variety of cations tested. The constructed sensor displayed a Nernstian behavior (19.7 {+-} 0.3 mV/decade) in the concentration range of 1.0 Multiplication-Sign 10{sup -6} to 1.0 Multiplication-Sign 10{sup -2} mol L{sup -1} with detection limit of 5.0 Multiplication-Sign 10{sup -7} mol L{sup -1} and a short response time (< 10 s). The working pH range of the electrode was 3.5-10.1 and lifetime of the sensor was at least 10 weeks. Analysis of certified reference materials confirmed the accuracy of the proposed sensor. The electrode was successfully applied as an indicator electrode in gadolinium titration with EDTA. - Highlights: Black-Right-Pointing-Pointer A Gd{sup 3+}-PVC membrane sensor based on an ion carrier as sensing material is introduced. Black-Right-Pointing-Pointer This technique is very simple and it's not necessary to use sophisticated equipment. Black-Right-Pointing-Pointer This sensor shows good selectivity against other metal ions.

  20. Separation of aliphatic carboxylic acids and benzenecarboxylic acids by ion-exclusion chromatography with various cation-exchange resin columns and sulfuric acid as eluent.

    Science.gov (United States)

    Ohta, Kazutoku; Ohashi, Masayoshi; Jin, Ji-Ye; Takeuchi, Toyohide; Fujimoto, Chuzo; Choi, Seong-Ho; Ryoo, Jae-Jeong; Lee, Kwang-Pill

    2003-05-16

    The application of various hydrophilic cation-exchange resins for high-performance liquid chromatography (sulfonated silica gel: TSKgel SP-2SW, carboxylated silica gel: TSKgel CM-2SW, sulfonated polymethacrylate resin: TSKgel SP-5PW, carboxylated polymethacrylate resins: TSKgel CM-5PW and TSKgel OA-Pak A) as stationary phases in ion-exclusion chromatography for C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, butyric, isovaleric, valeric, isocaproic, caproic, 2-methylhexanoic and heptanoic acids) and benzenecarboxylic acids (pyromellitic, trimellitic, hemimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic, salicylic acids and phenol) was carried out using diluted sulfuric acid as the eluent. Silica-based cation-exchange resins (TSKgel SP-2SW and TSKgel CM-2SW) were very suitable for the ion-exclusion chromatographic separation of these benzenecarboxylic acids. Excellent simultaneous separation of these benzenecarboxylic acids was achieved on a TSKgel SP-2SW column (150 x 6 mm I.D.) in 17 min using a 2.5 mM sulfuric acid at pH 2.4 as the eluent. Polymethacrylate-based cation-exchange resins (TSKgel SP-5PW, TSKgel CM-5PW and TSKgel OA-Pak A) acted as advanced stationary phases for the ion-exclusion chromatographic separation of these C1-C7 aliphatic carboxylic acids. Excellent simultaneous separation of these C1-C7 acids was achieved on a TSKgel CM-5PW column (150 x 6 mm I.D.) in 32 min using a 0.05 mM sulfuric acid at pH 4.0 as the eluent.

  1. Determination of haloacetic acids in water by ion chromatography--method development.

    Science.gov (United States)

    Lopez-Avila, V; Liu, Y; Charan, C

    1999-01-01

    The microextraction/ion chromatographic (IC) method developed in this study involves extraction of 9 haloacetic acids (HAAs) from aqueous samples (acidified with sulfuric acid to a pH of copper sulfate pentahydrate and sodium sulfate) with methyl tert-butyl ether (MTBE), back extraction into reagent water, and analysis by IC with conductivity detection. The separation column consists of an Ion Pac AG-11 (2 mm id x 50 mm length) guard column and an Ion Pac AS-11 (2 mm id x 250 mm length) analytical column, and the concentration column is a 4 mm id x 35 mm length Dionex TAC-LP column. Use of the 2 mm id Dionex AS-11 column improved detection limits especially for trichloracetic acid (TCAA), bromodichloroacetic acid (BDCAA), dibromochloroacetic acid (DBCAA), and tribromoacetic acid (TBAA). The peak interfering with BCAA elutes at the same retention time as nitrate; however, we have not confirmed the presence of nitrate. Stability studies indicate that HAAs are stable in water for at least 8 days when preserved with ammonium chloride at 100 mg/L and stored at 4 degrees C in the dark. At day 30, recoveries were still high (e.g., 92.1-106%) for dichloroacetic acid (DCAA), BCAA, dibromoacetic acid (DBAA), trichloroacetic acid (TCAA), BDCAA, and DBCAA. However, recoveries of monochloroacetic acid (MCAA), monobromoacetic acid (MBAA), and TBAA were only 54.6, 56.8, and 66.8%, respectively. Stability studies of HAAs in H2SO4-saturated MTBE indicate that all compounds except TBAA are stable for 48 h when stored at 4 degrees C in the dark. TBAA recoveries dropped to 47.1% after 6 h of storage and no TBAA was detected after 48 h of storage. The method described here is only preliminary and was tested in only one laboratory. Additional research is needed to improve method performance.

  2. Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration

    Directory of Open Access Journals (Sweden)

    Musa Ahmad

    2017-11-01

    Full Text Available An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to any pH changes and could be used to determine the end-point of the acid-base titration.

  3. Electrochemical sensing of ammonium ion at the water/1,6-dichlorohexane interface.

    Science.gov (United States)

    Ribeiro, José A; Silva, F; Pereira, Carlos M

    2012-01-15

    In this work, ion transfer and facilitated ion transfer of ammonium ion by a lipophilic cyclodextrin is investigated at the water/1,6-dichlorohexane micro-interface, using electrochemical approaches (cyclic voltammetry, differential pulse voltammetry and square wave voltammetry). The association constant has been obtained for the complex between ammonium ion and the cyclodextrin. Experimental conditions for the analytical determination of ammonium ion were established and a detection limit of 0.12 μM was obtained. The amperometric sensor gave a current response proportional to the ammonium ion concentration in the range from 4.2 to 66 μM. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. The removal of uranium from acidic media using ion exchange and/or extraction chromatography

    International Nuclear Information System (INIS)

    FitzPatrick, J.R.; Schake, B.S.; Murphy, J.; Holmes, K.; West, M.H.

    1996-06-01

    The separation and purification of uranium from either nitric acid or hydrochloric acid media can be accomplished by using either solvent extraction or ion-exchange. Over the past two years at Los Alamos, emerging programs are focused on recapturing the expertise required to do limited, small-quantity processing of enriched uranium. During this period of time, we have been investigating ion-addition, waste stream polishing is associated with this effort in order to achieve more complete removal of uranium prior to recycle of the acid. Extraction chromatography has been demonstrated to further polish the uranium from both nitric and hydrochloric acid media thus allowing for a more complete recovery of the actinide material and creation of less waste during the processing steps

  5. Potentiometric Determination of Phytic Acid and Investigations of Phytate Interactions with Some Metal Ions.

    Science.gov (United States)

    Marolt, Gregor; Pihlar, Boris

    2015-01-01

    Determination of correct amount (concentration) of phytic acid is of vital importance when dealing with protonation and/or metal complexation equilibria. A novel approach for precise and reliable assay of phytic acid, based on the difference between end points by potentiometric titration, has been presented. Twelve phytic acid protons are classified into three groups of acidity, which enables detection of 2 to 3 distinct equivalent points (EPs) depending on experimental conditions, e.g. counter-ion concentration. Using the differences between individual EPs enables correct phytate determination as well as identification of potential contamination and/or determination of initial protonation degree. Impact of uncertainty of phytate amount on the calculation of protonation constants has been evaluated using computer simulation program (Hyperquad2013). With the analysis of titration curves different binding sites on phytate ligand have been proposed for complexation of Ca2+ and Fe3+ ions.

  6. NMR and spectroscopic studies on uranyl ion interaction with aspartic acid and asparagine

    International Nuclear Information System (INIS)

    Wieczorek, H.; Kozlowski, H.

    1980-01-01

    The carboxyl groups of peptides or proteins are quite effective in the binding of UO 2 +2 ion and as the first step in studies in that field aspartic acid has been chosen as the bi-carboxylic ligand. The data for UO 2 +2 -asparagine system are also presented in this communication as they complete the results obtained for the UO 2 +2 -aspartic acid system. (author)

  7. [Determination a variety of acidic gas in air of workplace by Ion Chromatography].

    Science.gov (United States)

    Li, Shiyong

    2014-10-01

    To establish a method for determination of a variety of acid gas in the workplace air by Ion Chromatography. (hydrofluoric acid, hydrogen chloride or hydrochloric acid, sulfur anhydride or sulfuric acid, phosphoric acid, oxalic acid). The sample in workplace air was collected by the porous glass plate absorption tube containing 5 ml leacheate. (Sulfuric acid fog, phosphoric acid aerosol microporous membrane after collection, eluted with 5 ml of eluent.) To separated by AS14+AG14 chromatography column, by carbonate (2.0+1.0) mmol/L (Na(2)CO(3)-NaHCO(3)) as eluent, flow rate of 1 ml/min, then analyzed by electrical conductivity detector. The retain time was used for qualitative and the peak area was used for quantitation. The each ion of a variety of acid gas in the air of workplace were excellent in carbonate eluent separation. The linear range of working curve of 0∼20 mg/L. The correlation coefficient r>0.999; lower detection limit of 3.6∼115 µg/L; quantitative limit of 0.012∼0.53 mg/L; acquisition of 15L air were measured, the minimum detection concentration is 0.004 0∼0.13 mg/m(3). The recovery rate is 99.7%∼101.1%. In the sample without mutual interference ions. Samples stored at room temperature for 7 days. The same analysis method, the detection of various acidic gases in the air of workplace, simple operation, good separation effect, high sensitivity, high detection efficiency, easy popularization and application.

  8. High density nitrogen-vacancy sensing surface created via He{sup +} ion implantation of {sup 12}C diamond

    Energy Technology Data Exchange (ETDEWEB)

    Kleinsasser, Ed E., E-mail: edklein@uw.edu [Department of Electrical Engineering, University of Washington, Seattle, Washington 98195-2500 (United States); Stanfield, Matthew M.; Banks, Jannel K. Q. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Zhu, Zhouyang; Li, Wen-Di [HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Shenzhen 518000 (China); Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong (China); Acosta, Victor M. [Department of Physics and Astronomy, Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Watanabe, Hideyuki [Correlated Electronics Group, Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Itoh, Kohei M. [School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Fu, Kai-Mei C., E-mail: kaimeifu@uw.edu [Department of Electrical Engineering, University of Washington, Seattle, Washington 98195-2500 (United States); Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)

    2016-05-16

    We present a promising method for creating high-density ensembles of nitrogen-vacancy centers with narrow spin-resonances for high-sensitivity magnetic imaging. Practically, narrow spin-resonance linewidths substantially reduce the optical and RF power requirements for ensemble-based sensing. The method combines isotope purified diamond growth, in situ nitrogen doping, and helium ion implantation to realize a 100 nm-thick sensing surface. The obtained 10{sup 17 }cm{sup −3} nitrogen-vacancy density is only a factor of 10 less than the highest densities reported to date, with an observed 200 kHz spin resonance linewidth over 10 times narrower.

  9. Potentiometric studies on mixed-ligand chelates of uranyl ion with carboxylic acid phenolic acids

    International Nuclear Information System (INIS)

    Bandiwadekar, S.P.; Chavar, A.M.

    1988-01-01

    Mixed ligand complexes of UO 2 2+ with bidentate carboxylic and phenolic acids have been studied potentiometrically at 30 ± 0.1degC and μ=0.2M (NaClO 4 ). 1:1 and 1:2 complexes of UO 2 2+ with phthalic acid (PTHA), maleic acid (MAE), malonic acid (MAL), quinolinic acid (QA), 5-sulphosalicylic acid (5-SSA), salicylic acid (SA), and only 1:1 complexes in the case of mandelic acid (MAD) have been detected. The formation of 1:1:1 mixed ligand complexes has been inferred from simultaneous equilibria in the present study. The values of ΔlogK, Ksub(DAL), Ksub(2LA) or Ksub(2AL) for the ternary complexes have been calculated. The stabilities of mixed ligand complexes depend on the size of the chelate ring and the stabilities of the binary complexes. (author). 15 refs

  10. Ion-exclusion chromatography with conductimetric detection of aliphatic carboxylic acids on a weakly acidic cation-exchange resin by elution with benzoic acid-beta-cyclodextrin.

    Science.gov (United States)

    Tanaka, Kazuhiko; Mori, Masanobu; Xu, Qun; Helaleh, Murad I H; Ikedo, Mikaru; Taoda, Hiroshi; Hu, Wenzhi; Hasebe, Kiyoshi; Fritz, James S; Haddad, Paul R

    2003-05-16

    In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression.

  11. Real-Time Study of the Interaction between G-Rich DNA Oligonucleotides and Lead Ion on DNA Tetrahedron-Functionalized Sensing Platform by Dual Polarization Interferometry.

    Science.gov (United States)

    Wang, Shuang; Lu, Shasha; Zhao, Jiahui; Huang, Jianshe; Yang, Xiurong

    2017-11-29

    G-quadruplex plays roles in numerous physiological and pathological processes of organisms. Due to the unique properties of G-quadruplex (e.g., forming G4/hemin complexes with catalytic activity and electron acceptability, binding with metal ions, proteins, fluorescent ligands, and so on), it has been widely applied in biosensing. But the formation process of G-quadruplex is not yet fully understood. Here, a DNA tetrahedron platform with higher reproducibility, regenerative ability, and time-saving building process was coupled with dual polarization interferometry technique for the real-time and label-free investigation of the specific interaction process of guanine-rich singled-stranded DNA (G-rich ssDNA) and Pb 2+ . The oriented immobilization of probes greatly decreased the spatial hindrance effect and improved the accessibility of the probes to the Pb 2+ ions. Through real-time monitoring of the whole formation process of the G-quadruplex, we speculated that the probes on the tetrahedron platform initially stood on the sensing surface with a random coil conformation, then the G-rich ssDNA preliminarily formed unstable G-quartets by H-bonding and cation binding, subsequently forming a completely folded and stable quadruplex structure through relatively slow strand rearrangements. On the basis of these studies, we also developed a novel sensing platform for the specific and sensitive determination of Pb 2+ and its chelating agent ethylenediaminetetraacetic acid. This study not only provides a proof-of-concept for conformational dynamics of G-quadruplex-related drugs and pathogenes, but also enriches the biosensor tools by combining nanomaterial with interfaces technique.

  12. Melt quenched vanadium oxide embedded in graphene oxide sheets as composite electrodes for amperometric dopamine sensing and lithium ion battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Sreejesh, M. [Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Shenoy, Sulakshana [Functional Nanostructured Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Sridharan, Kishore, E-mail: kishore@nitk.edu.in [Functional Nanostructured Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Kufian, D.; Arof, A.K. [Centre for Ionics, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nagaraja, H.S., E-mail: nagaraja@nitk.edu.in [Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India)

    2017-07-15

    Highlights: • Layered vanadium oxides (MVO) are prepared through melt quenching process. • MVO is hydrothermally treated with graphene oxide to form MVGO composites. • Dopamine detection capacity using MVGO is 0.07 μM with good selectivity. • Sensitivity of dopamine detection is 25.02 μA mM{sup −1} cm{sup −2}. • Discharge capacity of MVGO electrode is 200 mAhg{sup −1} after 10 cycles. - Abstract: Electrochemical sensors and lithium-ion batteries are two important topics in electrochemistry that have attracted much attention owing to their extensive applications in enzyme-free biosensors and portable electronic devices. Herein, we report a simple hydrothermal approach for synthesizing composites of melt quenched vanadium oxide embedded on graphene oxide of equal proportion (MVGO50) for the fabrication of electrodes for nonenzymatic amperometic dopamine sensor and lithium-ion battery applications. The sensing performance of MVGO50 electrodes through chronoamperometry studies in 0.1 M PBS solution (at pH 7) over a wide range of dopamine concentration exhibited a highest sensitivity of 25.02 μA mM{sup −1} cm{sup −2} with the lowest detection limit of 0.07 μM. In addition, the selective sensing capability of MVGO50 was also tested through chronoamperometry studies by the addition of a very small concentration of dopamine (10 μM) in the presence of a fairly higher concentration of uric acid (10 mM) as the interfering species. Furthermore, the reversible lithium cycling properties of MVGO50 are evaluated by galvanostatic charge-discharge cycling studies. MVGO50 electrodes exhibited enhanced rate capacity of up to 200 mAhg{sup −1} at a current of 0.1C rate and remained stable during cycling. These results indicate that MVGO composites are potential candidates for electrochemical device applications.

  13. Solid-state emissive triarylborane-based BODIPY dyes: photophysical properties and fluorescent sensing for fluoride and cyanide ions.

    Science.gov (United States)

    Fu, Guang-Liang; Pan, Hong; Zhao, Yi-Hong; Zhao, Cui-Hua

    2011-12-07

    We disclose two novel BODIPY dyes, which contain the bulky substituent, [(4-dimesitylboryl)phenyl]ethynyl at 2- and 2,6-positions. The steric bulkiness of the boryl group is effective to suppress the intermolecular interaction in the solid state and thus these two compounds display intense fluorescence not only in solution but also in the solid state. In addition, the BODIPY dyes display sensitive fluorescence responses to fluoride and cyanide anions through the complexation with the boron center of the boryl group and the subsequent decomposition of the BODIPY core, illustrating their potential uses for the fluorescence sensing of fluoride and cyanide ions.

  14. Acidity field of soils as ion-exchange systems and the diagnostics of genetic soil horizons

    Science.gov (United States)

    Kokotov, Yu. A.; Sukhacheva, E. Yu.; Aparin, B. F.

    2014-12-01

    For the comprehensive description of the acidity of a two-phase ion-exchange system, we should analyze two curves of the ionite titration by a strong base in water and salt solutions and find the quantitative relationships between the corresponding pH characteristics. An idea of the three-dimensional field of acidity of ion-exchange systems (the phase space of the soil acidity characteristics) and its three two-dimensional projections is suggested. For soils, three interrelated characteristics—the pH values of the salt and water extracts and the degree of base saturation—can serve as spatial coordinates for the acidity field. Representation of factual data in this field makes it possible to compare and analyze the acidity characteristics of different soils and soil horizons and to determine their specific features. Differentiation of the field into separate volumes allows one to present the data in a discrete form. We have studied the distribution patterns of the groups of soil horizons from Leningrad oblast and other regions of northwestern Russia in the acidity field. The studied samples are grouped in different partially overlapping areas of the projections of the acidity field. The results of this grouping attest to the correctness of the modern classification of Russian soils. A notion of the characteristic soil area in the acidity field is suggested; it can be applied to all the soils with a leaching soil water regime.

  15. Silver ions-mediated conformational switch: facile design of structure-controllable nucleic acid probes.

    Science.gov (United States)

    Wang, Yongxiang; Li, Jishan; Wang, Hao; Jin, Jianyu; Liu, Jinhua; Wang, Kemin; Tan, Weihong; Yang, Ronghua

    2010-08-01

    Conformationally constraint nucleic acid probes were usually designed by forming an intramolecular duplex based on Watson-Crick hydrogen bonds. The disadvantages of these approaches are the inflexibility and instability in complex environment of the Watson-Crick-based duplex. We report that this hydrogen bonding pattern can be replaced by metal-ligation between specific metal ions and the natural bases. To demonstrate the feasibility of this principle, two linear oligonucleotides and silver ions were examined as models for DNA hybridization assay and adenosine triphosphate detection. The both nucleic acids contain target binding sequences in the middle and cytosine (C)-rich sequences at the lateral portions. The strong interaction between Ag(+) ions and cytosines forms stable C-Ag(+)-C structures, which promises the oligonucleotides to form conformationally constraint formations. In the presence of its target, interaction between the loop sequences and the target unfolds the C-Ag(+)-C structures, and the corresponding probes unfolding can be detected by a change in their fluorescence emission. We discuss the thermodynamic and kinetic opportunities that are provided by using Ag(+) ion complexes instead of traditional Watson-Crick-based duplex. In particular, the intrinsic feature of the metal-ligation motif facilitates the design of functional nucleic acids probes by independently varying the concentration of Ag(+) ions in the medium.

  16. Structural and Functional Analysis of the Escherichia coli Acid-Sensing Histidine Kinase EvgS.

    Science.gov (United States)

    Sen, Hrishiraj; Aggarwal, Nikhil; Ishionwu, Chibueze; Hussain, Nosheen; Parmar, Chandni; Jamshad, Mohammed; Bavro, Vassiliy N; Lund, Peter A

    2017-09-15

    The EvgS/EvgA two-component system of Escherichia coli is activated in response to low pH and alkali metals and regulates many genes, including those for the glutamate-dependent acid resistance system and a number of efflux pumps. EvgS, the sensor kinase, is one of five unconventional histidine kinases (HKs) in E. coli and has a large periplasmic domain and a cytoplasmic PAS domain in addition to phospho-acceptor, HK and dimerization, internal receiver, and phosphotransfer domains. Mutations that constitutively activate the protein at pH 7 map to the PAS domain. Here, we built a homology model of the periplasmic region of EvgS, based on the structure of the equivalent region of the BvgS homologue, to guide mutagenesis of potential key residues in this region. We show that histidine 226 is required for induction and that it is structurally colocated with a proline residue (P522) at the top of the predicted transmembrane helix that is expected to play a key role in passing information to the cytoplasmic domains. We also show that the constitutive mutations in the PAS domain can be further activated by low external pH. Expression of the cytoplasmic part of the protein alone also gives constitutive activation, which is lost if the constitutive PAS mutations are present. These findings are consistent with a model in which EvgS senses both external and internal pH and is activated by a shift from a tight inactive to a weak active dimer, and we present an analysis of the purified cytoplasmic portion of EvgS that supports this. IMPORTANCE One of the ways bacteria sense their environment is through two-component systems, which have one membrane-bound protein to do the sensing and another inside the cell to turn genes on or off in response to what the membrane-bound protein has detected. The membrane-bound protein must thus be able to detect the stress and signal this detection event to the protein inside the cell. To understand this process, we studied a protein that helps

  17. Degradation of acetic acid with sulfate radical generated by persulfate ions photolysis.

    Science.gov (United States)

    Criquet, Justine; Leitner, Nathalie Karpel Vel

    2009-09-01

    The photolysis of S(2)O(8)(2-) was studied for the removal of acetic acid in aqueous solution and compared with the H(2)O(2)/UV system. The SO(4)(-) radicals generated from the UV irradiation of S(2)O(8)(2-) ions yield a greater mineralization of acetic acid than the ()OH radicals. Acetic acid is oxidized by SO(4)(-) radicals without significant formation of intermediate by-products. Increasing system pH results in the formation of ()OH radicals from SO(4)(-) radicals. Maximum acetic acid degradation occurred at pH 5. The results suggest that above this pH, competitive reactions with the carbon mineralized inhibit the reaction of the solute with SO(4)(-) and also ()OH radicals. Scavenging effects of two naturally occurring ions were tested; in contrast to HCO(3)(-) ions, the presence of Cl(-) ions enhances the efficiency of the S(2)O(8)(2-)/UV process towards the acetate removal. It is attributed to the formation of the Cl() radical and its great reactivity towards acetate.

  18. Influence of the Functionalization Degree of Acidic Ion-Exchange Resins on Ethyl Octyl Ether Formation

    Czech Academy of Sciences Publication Activity Database

    Guilera, J.; Hanková, Libuše; Jeřábek, Karel; Ramírez, E.; Tejero, J.

    2014-01-01

    Roč. 78, MAY (2014), s. 14-22 ISSN 1381-5148 Grant - others:SEURDO(ES) CTQ2010-16047 Institutional support: RVO:67985858 Keywords : acidic ion - exchange resin * sulfonation degree * ISEC Subject RIV: CC - Organic Chemistry Impact factor: 2.515, year: 2014

  19. Influence of zirconium ion concentration in model extraction systems TBP - diluents - Zr+4 - nitric acid

    International Nuclear Information System (INIS)

    Rogoz, F.; Tlalka, M.

    1987-07-01

    In systems containing TBP, MBP, DBP and 1-butanol stable emulsions and precipitates are formed which separation is difficult in certain domain of concentration in zirconium ions. MPB and DBP increase stability of primary emulsion in kerosen and carbon tetrachloride but for different concentrations of nitric acid. Addition of 1-butanol decreases slightly the stability of primary emulsion [fr

  20. Explicit ions/implicit water generalized Born model for nucleic acids

    Science.gov (United States)

    Tolokh, Igor S.; Thomas, Dennis G.; Onufriev, Alexey V.

    2018-05-01

    The ion atmosphere around highly charged nucleic acid molecules plays a significant role in their dynamics, structure, and interactions. Here we utilized the implicit solvent framework to develop a model for the explicit treatment of ions interacting with nucleic acid molecules. The proposed explicit ions/implicit water model is based on a significantly modified generalized Born (GB) model and utilizes a non-standard approach to define the solute/solvent dielectric boundary. Specifically, the model includes modifications to the GB interaction terms for the case of multiple interacting solutes—disconnected dielectric boundary around the solute-ion or ion-ion pairs. A fully analytical description of all energy components for charge-charge interactions is provided. The effectiveness of the approach is demonstrated by calculating the potential of mean force for Na+-Cl- ion pair and by carrying out a set of Monte Carlo (MC) simulations of mono- and trivalent ions interacting with DNA and RNA duplexes. The monovalent (Na+) and trivalent (CoHex3+) counterion distributions predicted by the model are in close quantitative agreement with all-atom explicit water molecular dynamics simulations used as reference. Expressed in the units of energy, the maximum deviations of local ion concentrations from the reference are within kBT. The proposed explicit ions/implicit water GB model is able to resolve subtle features and differences of CoHex distributions around DNA and RNA duplexes. These features include preferential CoHex binding inside the major groove of the RNA duplex, in contrast to CoHex biding at the "external" surface of the sugar-phosphate backbone of the DNA duplex; these differences in the counterion binding patters were earlier shown to be responsible for the observed drastic differences in condensation propensities between short DNA and RNA duplexes. MC simulations of CoHex ions interacting with the homopolymeric poly(dA.dT) DNA duplex with modified (de

  1. A Comparative Study of Lithium Ion to Lead Acid Batteries for use in UPS Applications

    DEFF Research Database (Denmark)

    Stan, Ana-Irina; Swierczynski, Maciej Jozef; Stroe, Daniel Ioan

    2014-01-01

    Uninterruptible power supply (UPS) systems have incorporated in their structure an electrochemical battery which allows for smooth power supply when a power failure occurs. In general, UPS systems are based on lead acid batteries; mainly a valve regulated lead acid (VRLA) battery. Recently, lithium...... ion batteries are getting more and more attention for their use in the back-up power systems and UPSs, because of their superior characteristics, which include increased safety and higher gravimetric and volumetric energy densities. This fact allows them to be smaller in size and weight less than VRLA...... batteries, which are currently used in UPS applications. The main purpose of this paper is to analyze how Li-ion batteries can become a useful alternative to present VRLA. In this study, three different electrochemical battery technologies were investigated; two of the most appealing Li-ion chemistries...

  2. A simple chip free-flow electrophoresis for monosaccharide sensing via supermolecule interaction of boronic acid functionalized quencher and fluorescent dye.

    Science.gov (United States)

    Yin, Xiao-Yang; Dong, Jing-Yu; Wang, Hou-Yu; Li, Si; Fan, Liu-Yin; Cao, Cheng-Xi

    2013-08-01

    Here, a simple micro free-flow electrophoresis (μFFE) was developed for fluorescence sensing of monosaccharide via supermolecule interaction of synthesized boronic acid functionalized benzyl viologen (ο-BBV) and fluorescent dye. The μFFE contained two open electrode cavities and an ion-exchange membrane was sandwiched between two polymethylmethacrylate plates. The experiments demonstrated the following merits of developed μFFE: (i) up to 90.5% of voltage efficiency due to high conductivity of ion-exchange membrane; (ii) a strong ability against influence of bubble produced in two electrodes due to open design of electrode cavities; and (iii) reusable and washable separation chamber (45 mm × 17 mm × 100 μm, 77 μL) avoiding the discard of μFFE due to blockage of solute precipitation in chamber. Remarkably, the μFFE was first designed for the sensing of monosaccharide via the supermolecule interaction of synthesized ο-BBV, fluorescent dye, and monosaccharide. Under the optimized conditions, the minimum concentration of monosaccharide that could be detected was 1 × 10(-11) M. Finally, the developed device was used for the detection of 0.3 mM glucose spiked in human urine. All of the results demonstrated the feasibility of monosaccharide detection via the μFFE. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Breeding L(+)-lactic acid high productive mutant from xylose by nitrogen ions

    International Nuclear Information System (INIS)

    Yang Yingge; Li Wen; Liu Dan; Fan Yonghong; Wang Dongmei; Zheng Zhiming; Yu Zengliang

    2007-01-01

    In order to obtain higher L(+)-lactic acid yield strain fermentating from xylose, the original strain Rhizopus oryzae RLC41-6 was mutated by 10keV N + ion implantation. A mutant strain RQ4012 was obtained. After 72h shake-flask cultivation, the concentration of L(+)-lactic acid reached 74.37g/L, and the productivity was 1.03g/(L.h). Its lactic acid yield was 160% higher than that of the original one, and the mutant strain has high genetic stability. (authors)

  4. Aspartic acid-promoted highly selective and sensitive colorimetric sensing of cysteine in rat brain.

    Science.gov (United States)

    Qian, Qin; Deng, Jingjing; Wang, Dalei; Yang, Lifen; Yu, Ping; Mao, Lanqun

    2012-11-06

    Direct selective determination of cysteine in the cerebral system is of great importance because of the crucial roles of cysteine in physiological and pathological processes. In this study, we report a sensitive and selective colorimetric assay for cysteine in the rat brain with gold nanoparticles (Au-NPs) as the signal readout. Initially, Au-NPs synthesized with citrate as the stabilizer are red in color and exhibit absorption at 520 nm. The addition of an aqueous solution (20 μL) of cysteine or aspartic acid alone to a 200 μL Au-NP dispersion causes no aggregation, while the addition of an aqueous solution of cysteine into a Au-NP dispersion containing aspartic acid (1.8 mM) causes the aggregation of Au-NPs and thus results in the color change of the colloid from wine red to blue. These changes are ascribed to the ion pair interaction between aspartic acid and cysteine on the interface between Au-NPs and solution. The concentration of cysteine can be visualized with the naked eye and determined by UV-vis spectroscopy. The signal output shows a linear relationship for cysteine within the concentration range from 0.166 to 1.67 μM with a detection limit of 100 nM. The assay demonstrated here is highly selective and is free from the interference of other natural amino acids and other thiol-containing species as well as the species commonly existing in the brain such as lactate, ascorbic acid, and glucose. The basal dialysate level of cysteine in the microdialysate from the striatum of adult male Sprague-Dawley rats is determined to be around 9.6 ± 2.1 μM. The method demonstrated here is facile but reliable and durable and is envisaged to be applicable to understanding the chemical essence involved in physiological and pathological events associated with cysteine.

  5. Scandium and zirconium ion complexing with salicylic acid

    International Nuclear Information System (INIS)

    Fadeeva, V.I.; Kochetkova, S.K.

    1979-01-01

    A study has been made of the extraction of complexes containing scandium and zirconium compounds and salicylic acid by using benzene, nitrobenzene, chloroform and isoamyl alcohol. It is shown that in the metal concentration range 10 -5 -10 -3 mole/l scandium forms mononuclear complexes composed of Sc(HSal) 3 (pH 2 (pH>4), zirconium - polynuclear complexes Zrsub(x)(OH)sub(y)(HSal)sub(n), where the x:n ratio varies from 0.5 to 1.5. Stability constants have been calculated for the salicylate scandium complexes in aqueous solution, equal to β 1 =(3+-1)x10 2 ; β 2 =(5.0+-0.6)x10 4 ; β 3 =(5.3+-0.3)x10 6

  6. Scandium and zirconium ion complexing with salicylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Fadeeva, V I; Kochetkova, S K [Moskovskij Gosudarstvennyj Univ. (USSR)

    1979-08-01

    A study has been made of the extraction of complexes containing scandium and zirconium compounds and salicylic acid by using benzene, nitrobenzene, chloroform and isoamyl alcohol. It is shown that in the metal concentration range 10/sup -5/-10/sup -3/ mole/l scandium forms mononuclear complexes composed of Sc(HSal)/sub 3/ (pH<=4) and Sc(OH)(HSal)/sub 2/ (pH>4), zirconium - polynuclear complexes Zrsub(x)(OH)sub(y)(HSal)sub(n), where the x:n ratio varies from 0.5 to 1.5. Stability constants have been calculated for the salicylate scandium complexes in aqueous solution, equal to ..beta../sub 1/=(3+-1)x10/sup 2/; ..beta../sub 2/=(5.0+-0.6)x10/sup 4/; ..beta../sub 3/=(5.3+-0.3)x10/sup 6/.

  7. Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration

    OpenAIRE

    Musa Ahmad; T.W. Tan

    2017-01-01

    An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to ...

  8. Breeding study of hyper citric acid strain by progressive heavy ion irradiation

    International Nuclear Information System (INIS)

    Chen Jihong; Hu Wei; Li Wenjian; Liu Jing; Wang Shuyang; Wei Zihao

    2013-01-01

    Heavy "1"2C"6"+ ion beams in various high doses were employed to irradiate H3001 strain for screening Aspergillus niger strain for hyper citric acid production. Three high-yield strains were obtained after shaker fermentation test. Among the three strains, the strain hw317 was implemented shaker fermentation for stability test and 10∼100 L pilot fermentation tank for citric acid productive maximization. Acid-base neutralization method was applied to determinate the content of citric acid in fermented liquid. The results showed that: when the secondary heavy ion "1"2C"6"+ dose was 857.8 Gy, both of the fatality rate (94.5%) and the positive mutation rate (8%) were highest. Through the shaker fermentation tests and 10∼100 L pilot fermentation test, one strain hw317 was screened and obtained for hyper citric acid production. Consequently, the final citric acid acidity can reach up to 19.2±0.2% with controlling fermentation cycle for 60 h. (authors)

  9. Equilibrium studies on interactions of rare earth ions with phytic acid

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqi, K S; Shah, S A; Aqra, F M.A.M.; Tabassum, S; Zaidi, S A.A. [Aligarh Muslim Univ. (India). Dept. of Chemistry; Benlian, D [Centre de St Jerome, Cedex (France). Laboratoire de Chimie de Coordination

    1993-05-01

    The interaction between phytic acid and trivalent rare earth metal ions, viz., Ce[sup 3+], Pr[sup 3+], Nd[sup 3+], Sm[sup 3+], Gd[sup 3+], Tb[sup 3+], Dy[sup 3+] and HO[sup 3+] has been investigated potentiometrically at 25degC. The proton-ligand stability constants (pK[sub Y][sup H]) of phytic acid and the stability constants (logK) of metal complexes formed in aqueous medium ([mu] = 0.1 M NaClO[sub 4]) have been evaluated. The results indicate that eight protons of phytic acid are highly acidic, two are weakly acidic and two very weakly acidic, titrable in the pH ranges 1.2-4.9, 5.0-8.15 and 8.3-11.0 respectively. The stability of each phytic acid-lanthanide ion complex decreases with an increase in pH and follows the usual trend through the series. (author). 11 refs., 2 tabs.

  10. The Activation Mechanism of Bi3+ Ions to Rutile Flotation in a Strong Acidic Environment

    Directory of Open Access Journals (Sweden)

    Wei Xiao

    2017-07-01

    Full Text Available Lead hydroxyl compounds are known as rutile flotation of the traditional activated component, but the optimum pH range for flotation is 2–3 using styryl phosphoric acid (SPA as collector, without lead hydroxyl compounds in slurry solution. In this study, Bi3+ ions as a novel activator was investigated. The results revealed that the presence of Bi3+ ions increased the surface potential, due to the specific adsorption of hydroxyl compounds, which greatly increases the adsorption capacity of SPA on the rutile surface. Bi3+ ions increased the activation sites through the form of hydroxyl species adsorbing on the rutile surface and occupying the steric position of the original Ca2+ ions. The proton substitution reaction occurred between the hydroxyl species of Bi3+ ions (Bi(OHn+(3−n and the hydroxylated rutile surface, producing the compounds of Ti-O-Bi2+. The micro-flotation tests results suggested that Bi3+ ions could improve the flotation recovery of rutile from 61% to 90%, and from 61% to 64% for Pb2+ ions.

  11. The possibility of determining the activity coefficients of individual ions from acid-base titration data

    Science.gov (United States)

    Jano, I.; Hardcastle, J. E.

    1998-07-01

    A method is described for obtaining the activity coefficients of individual ions from experimental titration data. For this purpose, a general polyprotic acid-base-titration-curve equation is derived. The equation allows obtaining the dissociation equilibrium constants of the acid and the ratio of the activity coefficient of each ion to the activity coefficient of the undissociated acid directly from the titration data. Results obtained are compared with coefficients calculated using Debye-Hückel equation. A general equation relating the ionic strength to the pH of the titration medium is also established. Une méthode pour l'obtention des coefficients d'activité des ions individuels à partir des données expérimentales de titrage est établie. À ce but, une équation générale est dérivée pour représenter la courbe de titrage d'un acide avec une base. Cette équation permet d'obtenir les constants d'équilibre de dissociation de l'acide et le rapport de coefficient d'activité de chaque ion au coefficient d'activité de l'acide non-dissocié à partir des données de titrage. Les résultats ainsi obtenus sont comparés avec les coefficients calculés à l'aide de l'équation de Debye-Hückel. Une équation liant la force ionique au pH du milieu est établie aussi.

  12. Differential sensing of fluoride and cyanide ions by using Dicyano substituted benzimidazole probe

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Akul Sen; Garg, Aparna; Paul, Kamaldeep; Luxami, Vijay, E-mail: vluxami@thapar.edu

    2016-05-15

    Excited State Intramolecular Proton Transfer based benzimidazole derivative having push–pull effect has been synthesized and investigated their photophysical behavior towards various anions. The probe 2 has been used for selective estimation of F{sup −} and CN{sup −} anions and signaled the binding event through formation of new absorption band at 465 nm. The probe 2 opens different emission channels at 425 nm in the presence of CN{sup −} ions and two new emission bands at 435 nm and 365 nm in case of F{sup −} ions. The probe 2 behaved as chemodosimeter for CN{sup −} ions which have been proved by {sup 1}H NMR and whereas fluoride caused hydrogen bonding interactions with probe 2 and restricted the ESIPT emission at 505 nm from OH to nitrogen of benzimidazole moiety to release its enol emission. The differential behavior of F{sup −} ions and CN{sup −} have been confirmed through DFT calculations. - Graphical abstract: The probe 2 binds chemodosimetrically with cyanide ions and act as chemosensor for fluoride ion.

  13. Differential sensing of fluoride and cyanide ions by using Dicyano substituted benzimidazole probe

    International Nuclear Information System (INIS)

    Gupta, Akul Sen; Garg, Aparna; Paul, Kamaldeep; Luxami, Vijay

    2016-01-01

    Excited State Intramolecular Proton Transfer based benzimidazole derivative having push–pull effect has been synthesized and investigated their photophysical behavior towards various anions. The probe 2 has been used for selective estimation of F − and CN − anions and signaled the binding event through formation of new absorption band at 465 nm. The probe 2 opens different emission channels at 425 nm in the presence of CN − ions and two new emission bands at 435 nm and 365 nm in case of F − ions. The probe 2 behaved as chemodosimeter for CN − ions which have been proved by 1 H NMR and whereas fluoride caused hydrogen bonding interactions with probe 2 and restricted the ESIPT emission at 505 nm from OH to nitrogen of benzimidazole moiety to release its enol emission. The differential behavior of F − ions and CN − have been confirmed through DFT calculations. - Graphical abstract: The probe 2 binds chemodosimetrically with cyanide ions and act as chemosensor for fluoride ion.

  14. Activation of Short and Long Chain Fatty Acid Sensing Machinery in the Ileum Lowers Glucose Production in Vivo.

    Science.gov (United States)

    Zadeh-Tahmasebi, Melika; Duca, Frank A; Rasmussen, Brittany A; Bauer, Paige V; Côté, Clémence D; Filippi, Beatrice M; Lam, Tony K T

    2016-04-15

    Evidence continues to emerge detailing the myriad of ways the gut microbiota influences host energy homeostasis. Among the potential mechanisms, short chain fatty acids (SCFAs), the byproducts of microbial fermentation of dietary fibers, exhibit correlative beneficial metabolic effects in humans and rodents, including improvements in glucose homeostasis. The underlying mechanisms, however, remain elusive. We here report that one of the main bacterially produced SCFAs, propionate, activates ileal mucosal free fatty acid receptor 2 to trigger a negative feedback pathway to lower hepatic glucose production in healthy rats in vivo We further demonstrate that an ileal glucagon-like peptide-1 receptor-dependent neuronal network is necessary for ileal propionate and long chain fatty acid sensing to regulate glucose homeostasis. These findings highlight the potential to manipulate fatty acid sensing machinery in the ileum to regulate glucose homeostasis. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. On optimal length of hydrocarbon chain of fatty-acid collectors of rare earth ions

    International Nuclear Information System (INIS)

    Skrylev, L.D.; Sazonova, V.F.; Markina, Eh.L.

    1978-01-01

    The mechanism of the effect of the length of alkyl chain in fatty-acid collectors on the efficiency of flotation separation of the ions of rare earth elements (REE) collected by them has been investigated. REE flotation separation was studied on gadolinium chloride. Aqueous solutions of potassium caprinata, indecanate, laurate, tridecanate, myristate, pentadecanate and palmitate were used as collectors of Gd ions. The interaction of Gd ions with these compounds proceeds rapidly and is accompanied by stable colloidal solutions of Gd soaps being formed. Infrared spectra and radiograms of the sublates have been studied. It has been found that, with the number of carbon atoms in the collector molecule increasing from 10 to 16, the rate of flotation separation of Gd ions from solutions with pH 6 and 8 at first practically does not change (for potassium caprinate, undecanate and laurate), then drops sharply (potassium tridecanate and myristate), after which is again increases sharply (potassium pentadecanata and palmitate). The separation rate of Gd ions does not rise in solutions with pH 10. The nature of the sublate is shown to be determined by the solubility of the corresponing fatty acids and gadolinium soaps

  16. Spectrofluorometric and Molecular Modeling Studies on Binding of Nitrite Ion with Bovine Hemoglobin: Effect of Nitrite Ion on Amino Acid Residues

    Science.gov (United States)

    Madrakian, T.; Bagheri, H.; Afkhami, A.

    2015-05-01

    The interaction between nitrite ion and bovine hemoglobin was investigated by a spectrofluorometric technique. The experimental results indicated that the interaction causes a static quenching of the fluorescence of bovine hemoglobin, that the binding reaction is spontaneous, and that H-bonding interactions play a major role in binding of this ion to bovine hemoglobin. The formation constant for this interaction was calculated. Based on Förster's theory of nonradiative energy transfer, the binding distance between this ion and bovine hemoglobin was determined. Furthermore, the interaction of nitrite ion with tyrosine and tryptophan was investigated with synchronous fluorescence. There was no significant shift of the maximum emission wavelength with interactions of the mentioned ion with bovine hemoglobin, which implies that interaction of nitrite ion with bovine hemoglobin does not affect the microenvironment around the tryptophan and tyrosine residues. Furthermore, the effect of nitrite ion on amino acid residues of bovine hemoglobin was studied by a molecular docking technique.

  17. OAS proteins and cGAS: unifying concepts in sensing and responding to cytosolic nucleic acids.

    Science.gov (United States)

    Hornung, Veit; Hartmann, Rune; Ablasser, Andrea; Hopfner, Karl-Peter

    2014-08-01

    Recent discoveries in the field of innate immunity have highlighted the existence of a family of nucleic acid-sensing proteins that have similar structural and functional properties. These include the well-known oligoadenylate synthase (OAS) family proteins and the recently identified OAS homologue cyclic GMP-AMP (cGAMP) synthase (cGAS). The OAS proteins and cGAS are template-independent nucleotidyltransferases that, once activated by double-stranded nucleic acids in the cytosol, produce unique classes of 2'-5'-linked second messenger molecules, which - through distinct mechanisms - have crucial antiviral functions. 2'-5'-linked oligoadenylates limit viral propagation through the activation of the enzyme RNase L, which degrades host and viral RNA, and 2'-5'-linked cGAMP activates downstream signalling pathways to induce de novo antiviral gene expression. In this Progress article, we describe the striking functional and structural similarities between OAS proteins and cGAS, and highlight their roles in antiviral immunity.

  18. Adsorption of pertechnetate ion on various active carbons from mineral acid solutions

    International Nuclear Information System (INIS)

    Ito, K.

    1991-01-01

    The adsorption behavior of pertechnetate ion (TcO 4 - ) on active carbon has been studied for various acid solutions, taking as indicative value the distribution coefficient K d of Tc between active carbon surface and solution. In a system where the total anion concentration of the acid and its sodium salt was maintained constant, modifying the pH of the solution proved distinctly to influence the Tc adsorption behavior of active carbon: taking the case of active carbon derived from coconut shell, increasing the acidity raised K d ; around neutrality there occurred a level stage; in the alkali region, K d declined. The rise of K d in the acid region, however, was observed only with active carbon derived from coconut shell, from oil pitch or from saw dust; it failed to occur when the active carbon was derived from coal or from bone. With a hydrochloric acid system, the rise of K d started around 1 M (mol dm -1 ) HCl. Beyond 3 M, on the other hand, a breakthrough occurred, and K d declined with increasing acidity. With a nitric acid system, K d rose from 1 M, and the breakthrough occurred at 2 M. When the adsorption was left to equilibrate beyond 4 h, desorption displacement of TcO 4 - by a coexisting other anion was observed in the case of perchloric acid solutions of concentration above 0.1 M and with sulfuric acid solutions above 0.5 M. (author)

  19. Formation of complex precursors of amino acids by irradiation of simulated interstellar media with heavy ions

    Science.gov (United States)

    Kobayashi, K.; Suzuki, N.; Taniuchi, T.; Kaneko, T.; Yoshida, S.

    A wide variety of organic compounds have been detected in such extraterrestrial bodies as meteorites and comets Amino acids were identified in the extracts from Murchison meteorite and other carbonaceous chondrites It is hypothesized that these compounds are originally formed in ice mantles of interstellar dusts ISDs in molecular clouds by cosmic rays and ultraviolet light UV Formation of amino acid precursors by high energy protons or UV irradiation of simulated ISDs was reported by several groups The amino acid precursors were however not well-characterized We irradiated a frozen mixture of methanol ammonia and water with heavy ions to study possible organic compounds abiotically formed in molecular clouds by cosmic rays A mixture of methanol ammonia and water was irradiated with carbon beams 290 MeV u from a heavy ion accelerator HIMAC of National Institute of Radiological Sciences Japan Irradiation was performed either at room temperature liquid phase or at 77 K solid phase The products were characterized by gel filtration chromatography GFC FT-IR pyrolysis PY -GC MS etc Amino acids were analyzed by HPLC and GC MS after acid hydrolysis or the products Amino acids such as glycine and alanine were identified in the products in both the cases of liquid phase and solid phase irradiation Energy yields G-values of glycine were 0 014 liquid phase and 0 007 solid phase respectively Average molecular weights of the products were estimated as to 2300 in both the case Aromatic hydrocarbons N-containing heterocyclic

  20. Development of ion-exchange properties of bamboo charcoal modified with concentrated nitric acid

    Science.gov (United States)

    Khandaker, S.; Kuba, T.; Toyohara, Y.; Kamida, S.; Uchikawa, Y.

    2017-08-01

    The surface chemistry and the structural properties of activated carbon can be altered by the acidic modification. The objective of this study is to investigate the changes occurring in bamboo charcoal (BC) during activation with concentrated nitric acid. Low temperature (500°C) carbonized BC has been prepared and oxidized with 70% concentrated boiling nitric acid (BC-AC). The porous properties of the BC are analyzed with nitrogen adsorption isotherm at 77 K. The surface structure is observed by Field emission scanning electronic microscope (FESEM) and the surface functional groups are examined by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and the pH of the point of zero charge (pHPZC). The results reveal that severe oxidation with HNO3 considerably decreases the surface area of BC with enhanced pore widening and FESEM observation demonstrates the erosive effect of oxidation. The FTIR analysis detects that some absorption bands are assigned for carboxyl, aldehyde and ketone groups on BC-AC. The XPS analysis also clearly shows that the ratio of oxygen and acidic functional groups has been enriched significantly on the BC-AC. The low pHPZC value of BC-AC confirms that the surface is highly acidic for the fixation of acidic functional groups on surface. In general, the existence of the abundant amount of acidic functional groups on adsorbents enhances the sorption of heavy metals ions in aqueous solution. Therefore, it is strongly expected that the modified BC, activated under the proposed conditions would be a promising ion exchanger in aqueous solution and can be applied for the adsorption of different heavy metal ions and radioactive materials from effluent.

  1. Removal of uranyl ions by p-hexasulfonated calyx[6]arene acid

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, Ioana-Carmen [R and D National Institute for Metals and Radioactive Resources–ICPMRR, B-dul Carol I No.70, Sector 2, Bucharest 020917 (Romania); Petru, Filip [“C.D. Nenitescu” Institute of Organic Chemistry, Splaiul Independentei 202B, Sector 6, Bucharest 71141 (Romania); Humelnicu, Ionel [“Al.I. Cuza” University of Iasi, The Faculty of Chemistry, Bd. Carol-I No. 11, Iasi 700506 (Romania); Mateescu, Marina [National R and D Institute for Chemistry and Petrochemistry, Splaiul Independenţei No. 202, Bucharest 060021 (Romania); Militaru, Ecaterina [R and D National Institute for Metals and Radioactive Resources–ICPMRR, B-dul Carol I No.70, Sector 2, Bucharest 020917 (Romania); Humelnicu, Doina, E-mail: doinah@uaic.ro [“Al.I. Cuza” University of Iasi, The Faculty of Chemistry, Bd. Carol-I No. 11, Iasi 700506 (Romania)

    2014-10-15

    Radioactive pollution is a significant threat for the people’s health. Therefore highly effective radioactive decontamination methods are required. Ion exchange, biotechnologies and phytoremediation in constructed wetlands have been used as radioactive decontamination technologies for uranium contaminated soil and water remediation. Recently, beside those classical methods the calix[n]arenic derivatives’ utilization as radioactive decontaminators has jogged attention. The present work aims to present the preliminary research results of uranyl ion sorption studies on the p-hexasulfonated calyx[6]arenic acid. The effect of temperature, contact time, sorbent amount and uranyl concentration variation on sorption efficiency was investigated. Isotherm models revealed that the sorption process fit better Langmuir isotherm.

  2. Strong ion difference in urine: new perspectives in acid-base assessment.

    OpenAIRE

    Gattinoni, L.; Carlesso, E.; Cadringher, P.; Caironi, P.

    2006-01-01

    The plasmatic strong ion difference (SID) is the difference between positively and negatively charged strong ions. At pH 7.4, temperature 37°C and partial carbon dioxide tension 40 mmHg, the ideal value of SID is 42 mEq/l. The buffer base is the sum of negatively charged weak acids ([HCO3 -], [A-], [H2PO4 -]) and its normal value is 42 mEq/l. According to the law of electroneutrality, the amount of positive and negative charges must be equal, and therefore the SID value is equal to the buffer...

  3. Photodegradation of bisphenol A in simulated lake water containing algae, humic acid and ferric ions

    Energy Technology Data Exchange (ETDEWEB)

    Peng Zhang' e [School of Resources and Environmental Science, Wuhan University, Wuhan 430079 (China)]. E-mail: zhepeng@126.com; Wu Feng [School of Resources and Environmental Science, Wuhan University, Wuhan 430079 (China)]. E-mail: fengwu@whu.edu.cn; Deng Nansheng [School of Resources and Environmental Science, Wuhan University, Wuhan 430079 (China)]. E-mail: nsdengwhu@163.com

    2006-12-15

    The photodegradation of bisphenol A (BPA), a suspected endocrine disruptor (ED), in simulated lake water containing algae, humic acid and Fe{sup 3+} ions was investigated. Algae, humic acid and Fe{sup 3+} ions enhanced the photodegradation of BPA. Photodegradation efficiency of BPA was 36% after 4 h irradiation in the presence of 6.5 x 10{sup 9} cells L{sup -1} raw Chlorella vulgaris, 4 mg L{sup -1} humic acid and 20 {mu}mol L{sup -1} Fe{sup 3+}. The photodegradation efficiency of BPA was higher in the presence of algae treated with ultrasonic than that without ultrasonic. The photodegradation efficiency of BPA in the water only containing algae treated with ultrasonic was 37% after 4 h irradiation. The algae treated with heating can also enhance the photodegradation of BPA. This work helps environmental scientists to understand the photochemical behavior of BPA in lake water. - Algae, humic acid and ferric ions can induce the photodegradation of bisphenol A in an aqueous environment.

  4. Facile synthesis of improved room temperature gas sensing properties of TiO2 nanostructures: Effect of acid treatment

    CSIR Research Space (South Africa)

    Tshabalala, Zamaswazi P

    2016-03-01

    Full Text Available and Actuators B: Chemical Facile synthesis of improved room temperature gas sensing properties of TiO2 nanostructures: Effect of acid treatment Z.P. Tshabalalaa,b, D.E. Motaunga,∗, G.H. Mhlongoa,∗, O.M. Ntwaeaborwab,∗ a DST/CSIR, National Centre...

  5. A simple and selective colorimetric mercury (II) sensing system based on chitosan stabilized gold nanoparticles and 2,6-pyridinedicarboxylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Kun; Siegel, Gene; Tiwari, Ashutosh, E-mail: tiwari@eng.utah.edu

    2017-02-01

    The development of simple and cost-effective methods for the detection and treatment of Hg{sup 2+} in the environment is an important area of research due to the serious health risk that Hg{sup 2+} poses to humans. Colorimetric sensing based on the induced aggregation of nanoparticles is of great interest since it offers a low cost, simple, and relatively rapid procedure, making it perfect for on-site analysis. Herein we report the development of a simple colorimetric sensor for the selective detection and estimation of mercury ions in water, based on chitosan stabilized gold nanoparticles (AuNPs) and 2,6-pyridinedicarboxylic acid (PDA). In the presence of Hg{sup 2+}, PDA induces the aggregation of AuNPs, causing the solution to change colors varying from red to blue, depending on the concentration of Hg{sup 2+}. The formation of aggregated AuNPs in the presence of Hg{sup 2+} was confirmed using transmission electron microscopy (TEM) and UV–Vis spectroscopy. The method exhibits linearity in the range of 300 nM to 5 μM and shows excellent selectivity towards Hg{sup 2+} among seventeen different metal ions and was successfully applied for the detection of Hg{sup 2+} in spiked river water samples. The developed technique is simple and superior to the existing techniques in that it allows detection of Hg{sup 2+} using the naked eye and simple and rapid colorimetric analysis, which eliminates the need for sophisticated instruments and sample preparation methods. - Highlights: • A simple colorimetric method for detection of Hg{sup 2+} in water was proposed. • Au nanoparticles and 2,6-pyridinedicarboxylic acid were used for sensing Hg{sup 2+}. • Sensing mechanisms were demonstrated by TEM and UV–Visible measurements. • It showed the solution color changes from red to blue upon addition of Hg{sup 2+}. • The method selectively detected Hg{sup 2+} among seventeen different metal ions.

  6. ANTS-anchored Zn-Al-CO{sub 3}-LDH particles as fluorescent probe for sensing of folic acid

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Pengfei; Liu, Dan; Liu, Yanhuan [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China); Li, Lei, E-mail: lilei@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China)

    2016-09-15

    A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO{sub 3}-layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn{sup 2+} ions of Zn-Al-CO{sub 3}-LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO{sub 3}-LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO{sub 3} groups in ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO{sub 3}-LDH particles can afford a very sensitive system for the sensing FA in aqueous solution. - Highlights: • A novel fluorescent nanosensor has been developed. • The sensor exhibited highly sensitive and selective response to FA. • The fluorescence quenching was fitted to Stern–Volmer equation. • The linear response range was 1–200 μM with a limit of detection of 0.1 μM.

  7. Investigation of ion exchangers with groups of aminoethylphosphonium acids and their derivatives

    International Nuclear Information System (INIS)

    Lejkin, Yu.A.; Ratajchak, V.; Korshak, V.V.

    1977-01-01

    Acid-base equilibrium has been investigated on polymeric chelate compounds with groups of aminoethylphosphonium acids, AEP-3, their monoesters, AEP-2 and diesters, AEP-1. Values of the acid-base equilibrium constants of the chelate compounds have been calculated, and schemes of consecutive protonation of the ion exchangers investigated are suggested. Sorption characteristics for the series of U, Fe, Co, Ca, Th metals have been investigated. Values of the distribution coefficients and capacity from acid-base media of various concentration are given. Assumptions are made, which explain an increase in the selectivity and affinity in the series of the chelate compounds investigated. In the AEP-3 > AEP series-2 > AEP-1 weakening of the affinity to U, Fe, Th is observed

  8. Fused Silica Ion Trap Chip with Efficient Optical Collection System for Timekeeping, Sensing, and Emulation

    Science.gov (United States)

    2015-01-22

    17 This can be accomplished by including Raman side-band cooling after Doppler cooling the system for all modes except the soft rotational mode, at...trapped ions. Nature 2010, 465(7268): 590 –593. 4. Islam R, Edwards EE, Kim K, Korenblit S, Noh C, Carmichael H, Lin G-D, Duan L-M, Wang C-CJ, Freericks

  9. A novel cyanide ion sensing approach based on Raman scattering for the detection of environmental cyanides.

    Science.gov (United States)

    Yan, Fei; Gopal Reddy, C V; Zhang, Yan; Vo-Dinh, Tuan

    2010-09-01

    This paper describes a direct optical approach based on Raman scattering for selective and sensitive detection of cyanide ions in aqueous environment without requiring time-consuming sample pretreatment and the formation of hydrogen cyanide. Due to the strong affinity between copper (I) and cyanide ion, evaporated copper (I) iodide (CuI) thin films are shown to be excellent substrates for selective recognition of free cyanide ions in aqueous matrices. The amount of cyanide ion retained by the copper (I) in the CuI thin films reflects its actual concentration in tested samples, and the subsequent Raman measurements of the substrate are shown to be capable of detecting toxic cyanide content at levels under international drinking water standard and environmental regulatory concentrations. Measurements obtained from the same batch of evaporated CuI thin films (approximately 100-nm thickness) show excellent linearity over a variety of cyanide concentrations ranging from 1.5 microM to 0.15 mM. This detection method offers the advantage of selectively detecting cyanides causing a health hazard while avoiding detection of other common interfering anions such as Cl-, Br-, PO4(3-), SO4(2-), NO2-, S2- and SCN-. Coupled with portable Raman systems that are commercially available, our detection approach will provide on-site monitoring capability with little sample preparation or instrument supervision, which will greatly expedite the assessment of potential environmental cyanide risks. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  10. Electrical Double Layer-Induced Ion Surface Accumulation for Ultrasensitive Refractive Index Sensing with Nanostructured Porous Silicon Interferometers.

    Science.gov (United States)

    Mariani, Stefano; Strambini, Lucanos Marsilio; Barillaro, Giuseppe

    2018-03-23

    Herein, we provide the first experimental evidence on the use of electrical double layer (EDL)-induced accumulation of charged ions (using both Na + and K + ions in water as the model) onto a negatively charged nanostructured surface (e.g., thermally growth SiO 2 )-Ion Surface Accumulation, ISA-as a means of improving performance of nanostructured porous silicon (PSi) interferometers for optical refractometric applications. Nanostructured PSi interferometers are very promising optical platforms for refractive index sensing due to PSi huge specific surface (hundreds of m 2 per gram) and low preparation cost (less than $0.01 per 8 in. silicon wafer), though they have shown poor resolution ( R) and detection limit (DL) (on the order of 10 -4 -10 -5 RIU) compared to other plasmonic and photonic platforms ( R and DL on the order of 10 -7 -10 -8 RIU). This can be ascribed to both low sensitivity and high noise floor of PSi interferometers when bulk refractive index variation of the solution infiltrating the nanopores either approaches or is below 10 -4 RIU. Electrical double layer-induced ion surface accumulation (EDL-ISA) on oxidized PSi interferometers allows the interferometer output signal (spectral interferogram) to be impressively amplified at bulk refractive index variation below 10 -4 RIU, increasing, in turn, sensitivity up to 2 orders of magnitude and allowing reliable measurement of refractive index variations to be carried out with both DL and R of 10 -7 RIU. This represents a 250-fold-improvement (at least) with respect to the state-of-the-art literature on PSi refractometers and pushes PSi interferometer performance to that of state-of-the-art ultrasensitive photonics/plasmonics refractive index platforms.

  11. Ion-pair high performance liquid chromatographic retention behavior of salicylic acid and its derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.W.; Chung, Y.S. [Chungbuk National University, Cheongju (Korea); Oh, S.K. [Handok Pharmaceuticals Co. Ltd., Chungbuk (Korea)

    1999-06-01

    The ion-pair high performance liquid chromatographic elution behavior of salicylic acid and its derivatives was studied with measuring capacity factor, k', changing the concentration of ion-pairing reagent (tetrabutylammonium chloride, TBACl) in mobile phase. As a result, it was found that k' of the samples increase at pH 7.2 as the TBACl concentration increase. The derivatives of salicylic acid were separated each other at an optimum mobile phase condition which was found from the observation of the retention behavior. The optimum mobile phase condition was methanol solution(MeOH:H{sub 2}O 30:70) containing 20 mM TBACl for the determination of salicylic acid and methanol solution (MeOH:H{sub 2}O 20:80) containing 40 mM TBACl for p-aminosalicylic acid at pH 7.2. The method has been applied for the analysis of the contents of salicylic acid derivatives in an aspirin tablet and a tuberculosis curing agent. 8 refs., 4 figs., 2 tabs.

  12. Dialkyldithiophosphoric acids - chemical properties and 5f and 4f elements ions extraction

    International Nuclear Information System (INIS)

    Pattee, D.

    1987-09-01

    This work is a contribution to the study of the properties of the dialkyldithiophosphoric acids and of the extraction of the 4f and 5f ions from weakly acidic nitrate and phosphate media. Following a complete bibliographic study, synthesis and purification of the di-2-ethylhexyl-dithiophosphoric acid (HDEHDTP) is studied. It is identified with chemical methods and spectroscopic methods (I.R., N.M.R., V.P.C.); its by products, the di-2-ethylhexyl (monothio) phosphoric acids (HDEHTP, HDEHP) are also identified and characterized. Stability against hydrolysis and radiolysis is determined. The extractive properties are studied for the 4f and 5f ions. The presence of a sulfur donor atom in HDEHDTP makes it inefficient for the extraction of trivalent lanthanides and actinides but brings out a certain selectivity for americium. For HDEHTP, the presence of an oxygen donor atom rubs out any selectivity and the extraction constants are greater. Selectivity of HDEHDTP is increased by TBP (tri-n-butylphosphate) in synergistic mixtures. The mechanism of extraction of hexavalent uranium from phosphoric medium is elucidated. A model is developed by NMR for the micellisation of the sodium salts of HDEHDTP, HDEHTP and HDEHP, and extrapolated it to the trivalent rare earth salts of the acids. The structures are verified by light scattering and low angle X-ray diffraction [fr

  13. Separation of hafnium from zirconium in sulfuric acid solutions using pressurized ion exchange

    International Nuclear Information System (INIS)

    Hurst, F.J.

    1981-01-01

    High-resolution pressurized ion exchange has been used successfully to study and separate hafnium and zirconium sulfate complexes by chromatographic elution from Dowex 50W-X8 (15 to 25 μm) resin with sulfuric acid solutions. Techniques were developed to continuously monitor the column effluents for zirconium and hafnium by reaction with fluorometric and colorimetric reagents. Since neither reagent was specific for either metal ion, peak patterns were initially identified by using the stable isotopes 90 Zr and 180 Hf as fingerprints of their elution position. Distribution ratios for both zirconium and hafnium decrease as the inverse fourth power of the sulfuric acid concentration below 2N and as the inverse second power at higher acid concentration. The hafnium-to-zirconium separation factor is approximately constant (approx. 8) over the 0.5 to 3N range. Under certain conditions, an unseparated fraction was observed that was not retained by the resin. The amount of this fraction which is thought to be a polymeric hydrolysis product appears to be a function of metal and sulfuric acid concentrations. Conditions are being sought to give the highest zirconium concentration and the lowest acid concentration that can be used as a feed material for commercial scale-up in the continuous annular chromatographic (CAC) unit without formation of the polymer

  14. Ion-exchange preparation of high-purity vanadium acid from industrial liquors

    International Nuclear Information System (INIS)

    Sajdakhmedov, U.A.; Arslanov, Sh.S.; Vulikh, A.I.

    1994-01-01

    The results of investigations on production of special-purity vanadium acid and vanadium oxide directly from process solutions (technical grade liquors) using ionites are presented. Potentiality of thorough purification of vanadium(5) oxide, when producing vanadium acid on the KU-2 cationite with subsequent purification on anionite, is shown. On the basis of the results obtained a principle flowsheet of ion-exchange production of high-purity vanadium(5) oxide from industrial liquors has been developed. 2 refs.; 1 fig.; 4 tabs

  15. Effect of hydrocarbon radical length of fatty acid collectors on flotation separation process of thorium ions

    International Nuclear Information System (INIS)

    Skrylev, L.D.; Perlova, O.V.; Sazonova, V.F.

    1991-01-01

    It is shown experimentally that the degree of flotation separation of thorium ions collected by their means increases firstly (potassium laurate), then decreases (potassium tridecanate) and after that increases again (potassium palminate) when increasing the length of the hydrocarbon radical of potassium soaps of saturated fatty acids. The first increase of the collector efficiency is due to the decrease of solubility of thorium-containing sublates, and drop and further increase is due to the change in colloidchemical properties of sublates

  16. Hydrometallurgical recovery of metal values from sulfuric acid leaching liquor of spent lithium-ion batteries.

    Science.gov (United States)

    Chen, Xiangping; Chen, Yongbin; Zhou, Tao; Liu, Depei; Hu, Hang; Fan, Shaoyun

    2015-04-01

    Environmentally hazardous substances contained in spent Li-ion batteries, such as heavy metals and nocuous organics, will pose a threat to the environment and human health. On the other hand, the sustainable recycling of spent lithium-ion batteries may bring about environmental and economic benefits. In this study, a hydrometallurgical process was adopted for the comprehensive recovery of nickel, manganese, cobalt and lithium from sulfuric acid leaching liquor from waste cathode materials of spent lithium-ion batteries. First, nickel ions were selectively precipitated and recovered using dimethylglyoxime reagent. Recycled dimethylglyoxime could be re-used as precipitant for nickel and revealed similar precipitation performance compared with fresh dimethylglyoxime. Then the separation of manganese and cobalt was conducted by solvent extraction method using cobalt loaded D2EHPA. And McCabe-Thiele isotherm was employed for the prediction of the degree of separation and the number of extraction stages needed at specific experimental conditions. Finally, cobalt and lithium were sequentially precipitated and recovered as CoC2O4 ⋅ 2H2O and Li2CO3 using ammonium oxalate solution and saturated sodium carbonate solution, respectively. Recovery efficiencies could be attained as follows: 98.7% for Ni; 97.1% for Mn, 98.2% for Co and 81.0% for Li under optimized experimental conditions. This hydrometallurgical process may promise a candidate for the effective separation and recovery of metal values from the sulfuric acid leaching liquor. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Poly(acrylic acid) modifying bentonite with in-situ polymerization for removing lead ions.

    Science.gov (United States)

    He, Y F; Zhang, L; Yan, D Z; Liu, S L; Wang, H; Li, H R; Wang, R M

    2012-01-01

    In this paper, a new kind of poly(acrylic acid) modified clay adsorbent, the poly(acrylic acid)/bentonite composite (PAA/HB) was prepared by in-situ polymerization, and utilized to remove lead(II) ions from solutions. The maximum adsorption of adsorbent is at pH 5 for metal ions, whereas the adsorption starts at pH 2. The effects of contact time (5-60 min), initial concentration of metal ions (200-1,000 mg/L) and adsorbent dosage (0.04-0.12 g/100 mL) have been reported in this article. The experimental data were investigated by means of kinetic and equilibrium adsorption isotherms. The kinetic data were analyzed by the pseudo-first-order and pseudo-second-order equation. The experimental data fitted the pseudo-second-order kinetic model very well. Langmuir and Freundlich isotherms were tried for the system to better understand the adsorption isotherm process. The maximal adsorption capacity of the lead(II) ions on the PAA/HB, as calculated from the Langmuir model, was 769.2 mg/g. The results in this study indicated that PAA/HB was an attractive candidate for removing lead(II) (99%).

  18. Ion activity and distribution of heavy metals in acid mine drainage polluted subtropical soils

    International Nuclear Information System (INIS)

    Li Yongtao; Becquer, Thierry; Dai Jun; Quantin, Cecile; Benedetti, Marc F.

    2009-01-01

    The oxidative dissolution of mine wastes gives rise to acidic, metal-enriched mine drainage (AMD) and has typically posed an additional risk to the environment. The poly-metallic mine Dabaoshan in South China is an excellent test site to understand the processes affecting the surrounding polluted agricultural fields. Our objectives were firstly to investigate metal ion activity in soil solution, distribution in solid constituents, and spatial distribution in samples, secondly to determine dominant environment factors controlling metal activity in the long-term AMD-polluted subtropical soils. Soil Column Donnan Membrane Technology (SC-DMT) combined with sequential extraction shows that unusually large proportion of the metal ions are present as free ion in the soil solutions. The narrow range of low pH values prevents any pH effects during the binding onto oxides or organic matter. The differences in speciation of the soil solutions may explain the different soil degradation observed between paddy and non-paddy soils. - First evidence of the real free metal ion concentrations in acid mine drainage context in tropical systems

  19. Kinetics of uranium (4) oxidation with nitrous acid in the presence of oxalate-ions in nitric and perchloric acid solutions

    International Nuclear Information System (INIS)

    Nikitenko, S.I.; Astafurova, L.N.

    1991-01-01

    Kinetics of uranium (4) oxidation with nitrous acid in the presence of oxalate-ions are studied spectrometrically. It is shown that even at small oxalate concentrations a notable effect of tetravalent uranium stabilization is observed relatively to the oxidation with nitrous acid. In case of a significant excess of oxalate-ions the oxidation rate will be considerably slower as a result of the formation of U(4) bisoxalate complex

  20. Hypothalamic fatty acid sensing in Senegalese sole (Solea senegalensis): response to long-chain saturated, monounsaturated, and polyunsaturated (n-3) fatty acids.

    Science.gov (United States)

    Conde-Sieira, Marta; Bonacic, Kruno; Velasco, Cristina; Valente, Luisa M P; Morais, Sofia; Soengas, José L

    2015-12-15

    We assessed the presence of fatty acid (FA)-sensing mechanisms in hypothalamus of Senegalese sole (Solea senegalensis) and investigated their sensitivity to FA chain length and/or level of unsaturation. Stearate (SA, saturated FA), oleate (OA, monounsaturated FA of the same chain length), α-linolenate [ALA, a n-3 polyunsaturated fatty acid (PUFA) of the same chain length], and eicosapentanoate (EPA, a n-3 PUFA of a larger chain length) were injected intraperitoneally. Parameters related to FA sensing and neuropeptide expression in the hypothalamus were assessed after 3 h and changes in accumulated food intake after 4, 24, and 48 h. Three FA sensing systems characterized in rainbow trout were also found in Senegalese sole and were activated by OA in a way similar to that previously characterized in rainbow trout and mammals. These hypothalamic FA sensing systems were also activated by ALA, differing from mammals, where n-3 PUFAs do not seem to activate FA sensors. This might suggest additional roles and highlights the importance of n-3 PUFA in fish diets, especially in marine species. The activation of FA sensing seems to be partially dependent on acyl chain length and degree of saturation, as no major changes were observed after treating fish with SA or EPA. The activation of FA sensing systems by OA and ALA, but not SA or EPA, is further reflected in the expression of hypothalamic neuropeptides involved in the control of food intake. Both OA and ALA enhanced anorexigenic capacity compatible with the activation of FA sensing systems. Copyright © 2015 the American Physiological Society.

  1. Surface damage in cystine, an amino acid dimer, induced by keV ions.

    Science.gov (United States)

    Salles, R C M; Coutinho, L H; da Veiga, A G; Sant'Anna, M M; de Souza, G G B

    2018-01-28

    We have studied the interaction of an ion beam (17.6 keV F - ) with cystine, a dimer formed by the binding of two cysteine residues. Cystine can be considered as an ideal prototype for the study of the relevance of the disulfide (-S-S-) chemical bond in biomolecules. For the sake of comparison, the amino acid cysteine has also been subjected to the same experimental conditions. Characterization of the samples by XPS and NEXAFS shows that both pristine cystine and pristine cysteine are found as a dipolar ion (zwitterion). Following irradiation, the dimer and the amino acid show a tendency to change from the dipole ion form to the normal uncharged form. The largest spectral modification was observed in the high resolution XPS spectra obtained at around the N 1s core level for the two biomolecules. The 2p sulfur edge spectra of cysteine and cystine were much less sensitive to radiation effects. We suggest that the disulfide bond (-S-S-) remains stable before and after irradiation, contributing to the larger radiation stability of cystine as compared to the amino acid cysteine.

  2. Adsorption of Copper Ion using Acrylic Acid-g-Polyaniline in Aqueous Solution

    Science.gov (United States)

    Kamarudin, Sabariah; Mohammad, Masita

    2018-04-01

    A conductive polymer, polyaniline (PANI) has unique electrical behaviour, stable in the environment, easy synthesis and have wide application in various fields. Modification of PANI in order to improve its adsorption capacity has been done. In this study, the polyaniline-grafted acrylic acid has been prepared and followed by adsorption of copper ion in aqueous solution. Acrylic acid, PANI and acrylic acid-g-polyaniline (Aag-PANI) were characterized by FTIR and SEM to determine its characteristic. The adsorption capacity was investigated to study the removal capacity of Cu ion from aqueous solution. Two parameters were selected which are pH (2, 4 and 6) and initial metal ion concentration (50 mg/L, 100 mg/L and 200 mg/L). The maximum adsorption capacity for PANI and Aag-PANI are 1.7 mg/g and 64.6 mg/g, respectively, at an initial concentration of 100 mg/L. The Langmuir adsorption isotherm model and Freundlich adsorption isotherm model have been used and showed that it is heterolayer adsorption by follows the Freundlich isotherm model.

  3. Organoboron compounds as Lewis acid receptors of fluoride ions in polymeric membranes.

    Science.gov (United States)

    Jańczyk, Martyna; Adamczyk-Woźniak, Agnieszka; Sporzyński, Andrzej; Wróblewski, Wojciech

    2012-07-06

    Newly synthesized organoboron compounds - 4-octyloxyphenylboronic acid (OPBA) and pinacol ester of 2,4,6-trifluorophenylboronic acid (PE-PBA) - were applied as Lewis acid receptors of fluoride anions. Despite enhanced selectivity, the polymer membrane electrodes containing the lipophilic receptor OPBA exhibited non-Nernstian slopes of the responses toward fluoride ions in acidic conditions. Such behavior was explained by the lability of the B-O bond in the boronic acids, and the OH(-)/F(-) exchange at higher fluoride content in the sample solution. In consequence, the stoichiometry of the OPBA-fluoride complexes in the membrane could vary during the calibration, changing the equilibrium concentration of the primary anion in membrane and providing super-Nernstian responses. The proposed mechanism was supported by (19)F NMR studies, which indicated that the fluoride complexation proceeds more effectively in acidic solution leading mainly to PhBF(3)(-) species. Finally, the performances of the membranes based on the phenylboronic acid pinacol ester, with a more stable B-O bond, were tested. As it was expected, Nernstian fluoride responses were recorded for such membranes with worsened fluoride selectivity. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Preparation of the copolymer of acrylic acid and acrylamide grafted onto polyethylene and its complexation with samarium ion

    International Nuclear Information System (INIS)

    Kido, Junji; Akiba, Hideto; Nishide, Hiroyuki; Tsuchida, Eishun; Omichi, Hideki; Okamoto, Jiro.

    1986-01-01

    Acrylic acid (AA) and acrylamide (AAm) were graft-copolymerized onto polyethylene (PE) powder by the pre-irradiation method. Complex formation constants of Sm ion with the PE powder grafted with both AA and AAm (PE-g-(AA-co-AAm)) were larger than those with the PE powder grafted with AA (PE-g-AA). Sm ion was efficiently separated from the solution containing both Sm ion and a transition metal ion such as Cu ion. Even after the γ-ray irradiation on PE-g-(AA-co-AAm) and PE-g-AA, the adsorption did not decrease. (author)

  5. A Novel Passive Wireless Sensing Method for Concrete Chloride Ion Concentration Monitoring

    Directory of Open Access Journals (Sweden)

    Shuangxi Zhou

    2017-12-01

    Full Text Available In this paper, a novel approach for concrete chloride ion concentration measuring based on passive and wireless sensor tag is proposed. The chloride ion sensor based on RFID communication protocol is consisting of an energy harvesting and management circuit, a low dropout voltage regulator, a MCU, a RFID tag chip and a pair of electrodes. The proposed sensor harvests energy radiated by the RFID reader to power its circuitry. To improve the stability of power supply, a three-stage boost rectifier is customized to rectify the harvested power into dc power and step-up the voltage. Since the measured data is wirelessly transmitted, it contains miscellaneous noises which would decrease the accuracy of measuring. Thus, in this paper, the wavelet denoising method is adopted to denoise the raw data. Besides, a monitoring software is developed to display the measurement results in real-time. The measurement results indicate that the proposed passive sensor tag can achieve a reliable communication distance of 16.3 m and can reliably measure the chloride ion concentration in concrete.

  6. A Novel Passive Wireless Sensing Method for Concrete Chloride Ion Concentration Monitoring.

    Science.gov (United States)

    Zhou, Shuangxi; Sheng, Wei; Deng, Fangming; Wu, Xiang; Fu, Zhihui

    2017-12-11

    In this paper, a novel approach for concrete chloride ion concentration measuring based on passive and wireless sensor tag is proposed. The chloride ion sensor based on RFID communication protocol is consisting of an energy harvesting and management circuit, a low dropout voltage regulator, a MCU, a RFID tag chip and a pair of electrodes. The proposed sensor harvests energy radiated by the RFID reader to power its circuitry. To improve the stability of power supply, a three-stage boost rectifier is customized to rectify the harvested power into dc power and step-up the voltage. Since the measured data is wirelessly transmitted, it contains miscellaneous noises which would decrease the accuracy of measuring. Thus, in this paper, the wavelet denoising method is adopted to denoise the raw data. Besides, a monitoring software is developed to display the measurement results in real-time. The measurement results indicate that the proposed passive sensor tag can achieve a reliable communication distance of 16.3 m and can reliably measure the chloride ion concentration in concrete.

  7. Preparation and Microbiological Evaluation of Amphiphilic Kanamycin-Lipoamino Acid Ion-Pairs

    Directory of Open Access Journals (Sweden)

    Rosario Pignatello

    2014-05-01

    Full Text Available Amphiphilic ion-pairs of kanamycin (KAN were prepared by evaporation of a water-ethanol co-solution of KAN base and a lipoamino acid bearing a 12-carbon atoms alkyl side chain (LAA12, at different molar ratios. Infrared spectroscopy confirmed the structure of ion-pairs, while differential scanning calorimetry (DSC and powder X-ray diffractometry (PXRD studies supported the formation of new saline species with a different crystalline structure than the starting components. The solubility pattern shown in a range of both aqueous and organic solvents confirmed that the ion-pairs possess an amphiphilic character. The LAA12 counter-ion showed not to improve the antibacterial activity of KAN, suggesting that such chemical strategy is not able to favor the penetration of this drug inside the bacteria cells. Nevertheless, a slight improving, i.e., a one-fold dilution, was observed in E. coli. The present study can also serve as the basis for a further evaluation of LAA ion-pairing of antibiotics, as a means to improve the loading of hydrophilic drugs into lipid-based nanocarriers.

  8. Neuron attachment properties of carbon negative-ion implanted bioabsorbable polymer of poly-lactic acid

    International Nuclear Information System (INIS)

    Tsuji, Hiroshi; Sasaki, Hitoshi; Sato, Hiroko; Gotoh, Yasuhito; Ishikawa, Junzo

    2002-01-01

    Modification of a bioabsorbable polymer of poly-lactic acid (PLA) by negative carbon ion implantation was investigated with resect to radiation effects on surface physical properties and nerve-cell attachment properties. Carbon negative ions were implanted to PLA at energy of 5-30 keV with a dose of 10 14 -10 16 ions/cm 2 . Most C-implanted PLA samples showed contact angles near 80 deg. and almost same as that of unimplanted PLA, although a few samples at 5 keV and less 3x10 14 ions/cm 2 had contact angles larger than 90 deg. The attachment properties of nerve cells of PC-12h (rat adrenal phechromocytoma) in vitro were studied. PC-12h cells attached on the unimplanted region in C-implanted PLA samples at 5 and 10 keV. On the contrary, the nerve cells attached on only implanted region for the C-implanted PLA sample at 30 keV and 1x10 15 ions/cm 2

  9. Multi-shell model of ion-induced nucleic acid condensation

    Energy Technology Data Exchange (ETDEWEB)

    Tolokh, Igor S. [Department of Computer Science, Virginia Tech, Blacksburg, Virginia 24061 (United States); Drozdetski, Aleksander V. [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Pollack, Lois [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853-3501 (United States); Baker, Nathan A. [Advanced Computing, Mathematics, and Data Division, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Division of Applied Mathematics, Brown University, Providence, Rhode Island 02912 (United States); Onufriev, Alexey V. [Department of Computer Science, Virginia Tech, Blacksburg, Virginia 24061 (United States); Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2016-04-21

    We present a semi-quantitative model of condensation of short nucleic acid (NA) duplexes induced by trivalent cobalt(III) hexammine (CoHex) ions. The model is based on partitioning of bound counterion distribution around single NA duplex into “external” and “internal” ion binding shells distinguished by the proximity to duplex helical axis. In the aggregated phase the shells overlap, which leads to significantly increased attraction of CoHex ions in these overlaps with the neighboring duplexes. The duplex aggregation free energy is decomposed into attractive and repulsive components in such a way that they can be represented by simple analytical expressions with parameters derived from molecular dynamic simulations and numerical solutions of Poisson equation. The attractive term depends on the fractions of bound ions in the overlapping shells and affinity of CoHex to the “external” shell of nearly neutralized duplex. The repulsive components of the free energy are duplex configurational entropy loss upon the aggregation and the electrostatic repulsion of the duplexes that remains after neutralization by bound CoHex ions. The estimates of the aggregation free energy are consistent with the experimental range of NA duplex condensation propensities, including the unusually poor condensation of RNA structures and subtle sequence effects upon DNA condensation. The model predicts that, in contrast to DNA, RNA duplexes may condense into tighter packed aggregates with a higher degree of duplex neutralization. An appreciable CoHex mediated RNA-RNA attraction requires closer inter-duplex separation to engage CoHex ions (bound mostly in the “internal” shell of RNA) into short-range attractive interactions. The model also predicts that longer NA fragments will condense more readily than shorter ones. The ability of this model to explain experimentally observed trends in NA condensation lends support to proposed NA condensation picture based on the multivalent “ion

  10. Simultaneous Chronoamperometric Sensing of Ascorbic Acid and Acetaminophen at a Boron-Doped Diamond Electrode

    Directory of Open Access Journals (Sweden)

    Ciprian Radovan

    2008-06-01

    Full Text Available Cyclic voltammetry (CV and chronoamperometry (CA have been used to sense and determine simultaneously L-ascorbic acid (AA and acetaminophen (AC at a boron-doped diamond electrode (BDDE in a Britton-Robinson buffer solution. The calibration plots of anodic current peak versus concentration obtained from CV and CA data for both investigated compounds in single and di-component solutions over the concentration range 0.01 mM – 0.1 mM proved to be linear, with very good correlation parameters. Sensitivity values and RSD of 2-3% were obtained for various situations, involving both individual and simultaneous presence of AA and AC. The chronoamperometric technique associated with standard addition in sequential one step and/or two successive and continuous chronoamperograms at two characteristic potential levels represented a feasible option for the simultaneous determination of AA and AC in real sample systems such as pharmaceutical formulations. The average values indicated by the supplier were confirmed to a very close approximation from chronoamperomgrams by using several additions with the application of suitable current correction factors.

  11. Drosophila pheromone-sensing neurons expressing the ppk25 ion channel subunit stimulate male courtship and female receptivity.

    Science.gov (United States)

    Vijayan, Vinoy; Thistle, Rob; Liu, Tong; Starostina, Elena; Pikielny, Claudio W

    2014-03-01

    As in many species, gustatory pheromones regulate the mating behavior of Drosophila. Recently, several ppk genes, encoding ion channel subunits of the DEG/ENaC family, have been implicated in this process, leading to the identification of gustatory neurons that detect specific pheromones. In a subset of taste hairs on the legs of Drosophila, there are two ppk23-expressing, pheromone-sensing neurons with complementary response profiles; one neuron detects female pheromones that stimulate male courtship, the other detects male pheromones that inhibit male-male courtship. In contrast to ppk23, ppk25, is only expressed in a single gustatory neuron per taste hair, and males with impaired ppk25 function court females at reduced rates but do not display abnormal courtship of other males. These findings raised the possibility that ppk25 expression defines a subset of pheromone-sensing neurons. Here we show that ppk25 is expressed and functions in neurons that detect female-specific pheromones and mediates their stimulatory effect on male courtship. Furthermore, the role of ppk25 and ppk25-expressing neurons is not restricted to responses to female-specific pheromones. ppk25 is also required in the same subset of neurons for stimulation of male courtship by young males, males of the Tai2 strain, and by synthetic 7-pentacosene (7-P), a hydrocarbon normally found at low levels in both males and females. Finally, we unexpectedly find that, in females, ppk25 and ppk25-expressing cells regulate receptivity to mating. In the absence of the third antennal segment, which has both olfactory and auditory functions, mutations in ppk25 or silencing of ppk25-expressing neurons block female receptivity to males. Together these results indicate that ppk25 identifies a functionally specialized subset of pheromone-sensing neurons. While ppk25 neurons are required for the responses to multiple pheromones, in both males and females these neurons are specifically involved in stimulating

  12. Acidic pH and divalent cation sensing by PhoQ are dispensable for systemic salmonellae virulence.

    Science.gov (United States)

    Hicks, Kevin G; Delbecq, Scott P; Sancho-Vaello, Enea; Blanc, Marie-Pierre; Dove, Katja K; Prost, Lynne R; Daley, Margaret E; Zeth, Kornelius; Klevit, Rachel E; Miller, Samuel I

    2015-05-23

    Salmonella PhoQ is a histidine kinase with a periplasmic sensor domain (PD) that promotes virulence by detecting the macrophage phagosome. PhoQ activity is repressed by divalent cations and induced in environments of acidic pH, limited divalent cations, and cationic antimicrobial peptides (CAMP). Previously, it was unclear which signals are sensed by salmonellae to promote PhoQ-mediated virulence. We defined conformational changes produced in the PhoQ PD on exposure to acidic pH that indicate structural flexibility is induced in α-helices 4 and 5, suggesting this region contributes to pH sensing. Therefore, we engineered a disulfide bond between W104C and A128C in the PhoQ PD that restrains conformational flexibility in α-helices 4 and 5. PhoQ(W104C-A128C) is responsive to CAMP, but is inhibited for activation by acidic pH and divalent cation limitation. phoQ(W104C-A128C) Salmonella enterica Typhimurium is virulent in mice, indicating that acidic pH and divalent cation sensing by PhoQ are dispensable for virulence.

  13. Esterification of Palmitic Acid with Methanol in the Presence of Macroporous Ion Exchange Resin as Catalyst

    Directory of Open Access Journals (Sweden)

    Amelia Qarina Yaakob and Subhash Bhatia

    2012-10-01

    Full Text Available The esterification of palmitic acid with methanol was studied in a batch reactor using macro porous ion exchange resin Amberlyst 15 as a catalyst. Methyl palmitate was produced from the reaction between palmitic acid and methanol in the presence of catalyst. The effects of processing parameters, molar ratio of alcohol to acid M, (4-10, catalyst loading (0-10 g cat/liter, water inhibition (0-2 mol/liter, agitator speed (200-800 rpm and reaction temperature (343-373K were studied. The experimental kinetic data were correlated using homogenous as well as heterogeneous models (based on single as well as dual site mechanisms. The activation energy of the reaction was 11.552 kJ/mol for forward reaction whilst 5.464 kJ/mol for backward reaction. The experimental data fitted well with the simulated data obtained from the kinetic models. Keywords: Palmitic Acid, Methanol, Esterification, Ion Exchange Resin, Kinetics.

  14. Rapid self-heating and internal temperature sensing of lithium-ion batteries at low temperatures

    International Nuclear Information System (INIS)

    Zhang, Guangsheng; Ge, Shanhai; Xu, Terrence; Yang, Xiao-Guang; Tian, Hua; Wang, Chao-Yang

    2016-01-01

    Highlights: • Self-heating lithium-ion battery (SHLB) structure provided a practical solution to the poor performance at subzero temperatures. • We report an improved SHLB that heats from −20 °C to 0 °C in 12.5 seconds, or 56% more rapidly, while consuming 24% less energy than previously reported. • The nickel foil heating element embedded inside a SHLB cell plays a dominant role in rapid self-heating. • The embedded nickel foil can simultaneously perform as an internal temperature sensor (ITS). • 2-sheet design self-heats faster than 1-sheet design due to more uniform internal temperature distribution. - Abstract: The recently discovered self-heating lithium-ion battery structure provided a practical solution to the poor performance at subzero temperatures that has hampered battery technology for decades. Here we report an improved self-heating lithium-ion battery (SHLB) that heats from −20 °C to 0 °C in 12.5 seconds, or 56% more rapidly, while consuming 24% less energy than that reported previously. We reveal that a nickel foil heating element embedded inside a SHLB cell plays a dominant role in self-heating and we experimentally demonstrate that a 2-sheet design can achieve dramatically accelerated self-heating due to more uniform internal temperature distribution. We also report, for the first time, that this embedded nickel foil can simultaneously perform as an internal temperature sensor (ITS) due to the perfectly linear relationship between the foil’s electrical resistance and temperature.

  15. Preparation and adsorption behavior for metal ions and humic acid of chitosan derivatives crosslinked by irradiation

    International Nuclear Information System (INIS)

    Zhao Long; Mitomo, H.; Yoshii, F.

    2006-01-01

    Introduction: Removing metal ions and humic acid from water in water treatment has attracted much environment and health interests. Adsorbents, derived from a nature polymer, are desired in the viewpoints of environment-conscious technologies. Recently, some nature materials such as chitin, chitosan and their derivatives have been identified as an attractive option due to their distinctive properties. For an insoluble adsorbent based on these polymers to be obtained over a broad pH range, modification through crosslinking is required. Crosslinking agents such as glutaric dialdehyde and ethylene glycol diglycidyl ether are frequently used for modification. However, these crosslinking agents are not preferred because of their physiological toxicity. Radiation-crosslinking without any additive in the fabrication process results in a high-purity product. In a previous work, we applied ionizing radiation to induce the crosslinking of carboxymethylchitosan under highly concentrated paste-like conditions. The aim of this study is to investigate the adsorption behavior of metal ions, humic acid on irradiation-crosslinked carboxymethylchitosan. Experimental: Irradiation of chitosan samples at paste-like state was done with an electron beam. The solubility test of these crosslinked materials were investigated in acidic, alkaline media, and some organic solvents. Swelling and charged characteristic analyses demonstrated typically pH-sensitive properties of these crosslinked materials. Scanning electron microscopic images showed that the crosslinked samples possessed porous morphological structure. The adsorption studies were carried out by the batch method at room temperature. Adsorption of heavy metal ions (such as Cu 2+ , Cd 2+ ) and humic acid onto crosslinked samples was found to be strongly pH-dependent. Adsorption kinetic studies indicated the rapid removal of metal ions, and humic acid from the aqueous solutions. Also, isothermal adsorption data revealed that Cu 2

  16. Esterification of free fatty acids in waste cooking oils (WCO): Role of ion-exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Nalan Ozbay; Nuray Oktar; N. Alper Tapan [Gazi University, Ankara (Turkey). Faculty of Engineering and Architecture, Department of Chemical Engineering

    2008-08-15

    Although WCO plays a crucial role for the economical production of biodiesel, free fatty acid (FFA) level in the nature of WCO cause saponification problems during transesterification. Acidic ion-exchange resins can be used to decrease WCO free fatty acid level. In this study, activities of resins (Amberlyst-15 (A-15), Amberlyst-35 (A-35), Amberlyst-16 (A-16) and Dowex HCR-W2) in direct FFA esterification were examined in the temperature range of 50-60{sup o}C and the effect of catalyst amount (1-2 wt%) on FFA conversion was also analyzed. FFA conversion increased with increasing reaction temperature and catalyst amount. Order of catalytic activities was found as A-15 > A-35 > A-16 > Dowex HCR-W2. This was related to the size of average pore diameters and magnitude of BET surface area. 44 refs., 11 figs., 2 tabs.

  17. Interaction study of amino acids and the peptide aspartame with lanthanide (III) ions

    International Nuclear Information System (INIS)

    Carubelli, C.R.

    1990-01-01

    The interactions between the Nd(III) ion with the amino acids L-aspartic acid, L-glutamic acid and L-histidine and the peptide aspartame in aqueous solution were studied. The study was conducted by means of electronic spectroscopy with the Judd-Ofelt formalism for transition intensity parameters calculations. Several coordination compounds involving Nd(III), Eu(III), and Tb(III) and the ligands L-histidine and aspartame were synthesized and characterized in the solid state. Mixed compounds involving Eu(III) and Tb(III) with the same ligands were synthesized and characterized also. The characterization were achieved by chemical analysis, melting points, vibrational spectroscopy (IR) and powder X-ray diffractometry. (author)

  18. Complexation of trivalent actinide ions (Am3+, Cm3+) with humic acid: a comparison of different experimental methods

    International Nuclear Information System (INIS)

    Kim, J.I.; Rhee, D.S.; Wimmer, H.; Buckau, G.; Klenze, R.

    1993-01-01

    The complexation of trivalent metal ions with humic acid has been studied at pH 4 and 5 in 0.1 M NaClO 4 by three different experimental methods, i.e. UV spectroscopy, time resolved laser fluorescence spectroscopy (TRLFS) and ultrafiltration. The direct speciation of the metal ion and its humate complex in the reaction process has been made by UV spectroscopy for Am(III) in the micromolar concentration range and by TRLFS for Cm(III) in the nanomolar concentration range. The ultrafiltration is used with the lowest pore size of filter (ca. 1 nm) to separate the uncomplexed metal ion from its complexed species. The concentrations of both metal ion and humic acid are varied in such a manner that the effective functional groups of the humic acid becomes loaded with metal ions from 1% to nearly 100%. The loading capacity of the humic acid for the trivalent metal ion, determined separately at each pH, is introduced into the evaluation of complexation constants. The variation of the metal ion concentration from 6 x 10 -8 mol/l to 4 x 10 -5 mol/l does not show any effect on the complexation reaction. The three different methods give rise to constants being comparable with one another. The average value of the constants thus determined is log β = 6.24±0.28 for the trivalent actinide ions. (orig.)

  19. Enhancement of L(+)-Lactic Acid Production of Immobilized Rhizopus Oryzae Implanted by Ion Beams

    International Nuclear Information System (INIS)

    Fan Yonghong; Yang Yingge; Zheng Zhiming; Li Wen; Wang Peng; Yao Liming; Yu Zengliang

    2008-01-01

    Immobilized Rhizopus oryzae culturing may be a solution to the inhibited production of L(+)-lactic acid in submerged fermentation, which is caused by aggregated mycelia floc. In the present study, a R. oryzae mutant (RL6041) with a 90% conversion rate of glucose into L-lactic acid was obtained by N + implantation under the optimized conditions of a beam energy of 15 keV and a dose of 2.6 x 10 15 ions/cm 2 . Using polyurethane foam as the immobilization matrix, the optimal L-lactic acid production conditions were determined as 4 mm polyurethane foam, 150 r/min, 50 g/L ∼ 80 g/L of initial glucose, 38 deg. C and pH 6.0. 15-cycle repeated productions of L-lactic acid by immobilized RL6041 were performed under the optimized culturing conditions and over 80% of the glucose was converted into L-lactic acid in 30 hours on average. The results show that immobilized RL6041 is a promising candidate for continuous L-lactic acid production.

  20. Poly(acrylic acid)-templated silver nanoclusters as a platform for dual fluorometric turn-on and colorimetric detection of mercury (II) ions.

    Science.gov (United States)

    Tao, Yu; Lin, Youhui; Huang, Zhenzhen; Ren, Jinsong; Qu, Xiaogang

    2012-01-15

    An easy prepared fluorescence turn-on and colorimetric dual channel probe was developed for rapid assay of Hg(2+) ions with high sensitivity and selectivity by using poly(acrylic acid)-templated silver nanoclusters (PAA-AgNCs). The PAA-AgNCs exhibited weak fluorescence, while upon the addition of Hg(2+) ions, AgNCs gives a dramatic increase in fluorescence as a result of the changes of the AgNCs states. The detection limit was estimated to be 2 nM, which is much lower than the Hg(2+) detection requirement for drinking water of U.S. Environmental Protection Agency, and the turn-on sensing mode offers additional advantage to efficiently reduce background noise. Also, a colorimetric assay of Hg(2+) ions can be realized due to the observed absorbance changes of the AgNCs. More importantly, the method was successfully applied to the determination of Hg(2+) ions in real water samples, which suggests our proposed method has a great potential of application in environmental monitoring. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Polyurethane Ionophore-Based Thin Layer Membranes for Voltammetric Ion Activity Sensing.

    Science.gov (United States)

    Cuartero, Maria; Crespo, Gaston A; Bakker, Eric

    2016-06-07

    We report on a plasticized polyurethane ionophore-based thin film material (of hundreds of nanometer thickness) for simultaneous voltammetric multianalyte ion activity detection triggered by the oxidation/reduction of an underlying poly(3-octylthiophene) film. This material provides excellent mechanical, physical, and chemical robustness compared to other polymers. Polyurethane films did not exhibit leaching of lipophilic additives after rinsing with a direct water jet and exhibited resistance to detachment from the underlying electrode surface, resulting in a voltammetric current response with less than acrylate) ionophore-based membranes of the same thickness and composition exhibited a significant deterioration of the signal after identical treatment. While previously reported works emphasized fundamental advancement of multi-ion detection with multi-ionophore-based thin films, polyurethane thin membranes allow one to achieve real world measurements without sacrificing analytical performance. Indeed, polyurethane membranes are demonstrated to be useful for the simultaneous determination of potassium and lithium in undiluted human serum and blood with attractive precision.

  2. 2-Hydroxy-naphthyl functionalized mesoporous silica for fluorescence sensing and removal of aluminum ions.

    Science.gov (United States)

    Das, Trisha; Roy, Ankita; Uyama, Hiroshi; Roy, Partha; Nandi, Mahasweta

    2017-06-06

    Mesoporous silica functionalized with a 2-hydroxy-naphthyl moiety has been synthesized and characterized by standard techniques like powder X-ray diffraction, N 2 adsorption/desorption studies, transmission electron microscopy and spectral studies like FT-IR, UV-visible, fluorescence and 13 C and 29 Si solid state NMR. The functionalized silica material showed significant enhancement in its emission intensity in the presence of Al 3+ ions whereas other metal ions could not bring about any increase in its emission intensity. They either quench the emission or do not alter the intensity significantly making the functionalized material a fluorescence chemosensor for Al 3+ . The sensitivity of the probe towards Al 3+ has been determined to be high with a low limit of detection value. As functionalized silica is not soluble in common solvents, it has been effectively used to bind and remove Al 3+ from a solution. Theoretical calculations on a model system have been performed to investigate the electronic spectral transitions.

  3. Reactions of enolisable ketones with dichloroisocyanuric acid in absence and presence of added chloride ions – a kinetic study

    Directory of Open Access Journals (Sweden)

    Y. L. Kumar

    2015-01-01

    Full Text Available Kinetics of reactions of enolisable ketones (S = acetone/2-butanone with dichloroisocyanuric acid (DCICA were studied in aqueous acetic acid and perchloric acid media in absence and presence of added chloride ions. The reactions were found to be pseudo zero order and pseudo first order on [DCICA] in absence and presence of chloride ions respectively. Both in presence and absence of chloride ions, first order and fractional order in substrate and perchloric acid were observed respectively. An increase in the rate of reaction was observed with an increase in chloride ion concentration as well as acetic acid composition. The results were interpreted in terms of probable mechanisms involving (i rate-determining enol formation from the conjugate acid of the ketone (SH+ in the absence of added chloride ions and (ii rate-determining interaction of SH+ with the most effective molecular chlorine species produced by the hydrolysis of DCICA (rather than a rate-determining interaction of enol with chlorine in the presence of added chloride ions, prior to the rapid steps of product formation. DOI: http://dx.doi.org/10.4314/bcse.v29i1.12

  4. Radiation synthesis of chitosan beads grafted with acrylic acid for metal ions sorption

    International Nuclear Information System (INIS)

    Benamer, S.; Mahlous, M.; Tahtat, D.; Nacer-Khodja, A.; Arabi, M.; Lounici, H.; Mameri, N.

    2011-01-01

    Radiation-induced grafting of acrylic acid onto chitosan beads was performed in solution at a dose rate of 20.6 Gy/min of cobalt-60 gamma rays. The effect of absorbed dose on grafting yield was investigated. The characterization of the grafted material was performed by FTIR spectroscopy and the swelling measurements at different pHs. The grafting yield increased with the increase in dose, it reached 80% at 40 kGy irradiation dose. The removal of Pb and Cd ions from aqueous solutions was investigated with both ungrafted and grafted chitosan beads. The sorption behavior of the sorbents was examined through pH, kinetics and equilibrium measurements. Grafted chitosan beads presented higher sorption capacity for both metal ions than unmodified chitosan beads. - Highlights: → Pb and Cd ions are removed from aqueous solution by adsorption on chitosan beads. → Crosslinking process improves chemical stability of chitosan beads. → Radiation grafting of acrylic acid onto chitosan improves its metal adsorption capacity. → Increase in grafting degree enhances the adsorption capacity of the material. → Gamma radiation is a powerful tool for an accurate control of the grafting yield.

  5. Ion pair recognition by Zn-porphyrin/crown ether conjugates: visible sensing of sodium cyanide.

    Science.gov (United States)

    Kim, Yeon-Hwan; Hong, Jong-In

    2002-03-07

    Synthesis and complexation behavior of ditopic neutral receptors composed of both a Lewis-acidic binding site (zinc porphyrin moiety) and a Lewis-basic binding site (crown ether moiety) are reported; the receptors bound only NaCN in a ditopic fashion with a color change, and in contrast other sodium salts bound to the receptors in a monotopic fashion without a color change.

  6. Proton-sensing transistor systems for detecting ion leakage from plasma membranes under chemical stimuli.

    Science.gov (United States)

    Imaizumi, Yuki; Goda, Tatsuro; Schaffhauser, Daniel F; Okada, Jun-Ichi; Matsumoto, Akira; Miyahara, Yuji

    2017-03-01

    The membrane integrity of live cells is routinely evaluated for cytotoxicity induced by chemical or physical stimuli. Recent progress in bioengineering means that high-quality toxicity validation is required. Here, we report a pH-sensitive transistor system developed for the continuous monitoring of ion leakage from cell membranes upon challenge by toxic compounds. Temporal changes in pH were generated with high reproducibility via periodic flushing of HepG2 cells on a gate insulator of a proton-sensitive field-effect transistor with isotonic buffer solutions with/without NH 4 Cl. The pH transients at the point of NH 4 Cl addition/withdrawal originated from the free permeation of NH 3 across the semi-permeable plasma membranes, and the proton sponge effect produced by the ammonia equilibrium. Irreversible attenuation of the pH transient was observed when the cells were subjected to a membrane-toxic reagent. Experiments and simulations proved that the decrease in the pH transient was proportional to the area of the ion-permeable pores on the damaged plasma membranes. The pH signal was correlated with the degree of hemolysis produced by the model reagents. The pH assay was sensitive to the formation of molecularly sized pores that were otherwise not measurable via detection of the leakage of hemoglobin, because the hydrodynamic radius of hemoglobin was greater than 3.1nm in the hemolysis assay. The pH transient was not disturbed by inherent ion-transporter activity. The ISFET assay was applied to a wide variety of cell types. The system presented here is fast, sensitive, practical and scalable, and will be useful for validating cytotoxins and nanomaterials. The plasma membrane toxicity and hemolysis are widely and routinely evaluated in biomaterials science and biomedical engineering. Despite the recent development of a variety of methods/materials for efficient gene/drug delivery systems to the cytosol, the methodologies for safety validation remain unchanged in

  7. FAT/CD36: a major regulator of neuronal fatty acid sensing and energy homeostasis in rats and mice.

    Science.gov (United States)

    Le Foll, Christelle; Dunn-Meynell, Ambrose; Musatov, Serguei; Magnan, Christophe; Levin, Barry E

    2013-08-01

    Hypothalamic "metabolic-sensing" neurons sense glucose and fatty acids (FAs) and play an integral role in the regulation of glucose, energy homeostasis, and the development of obesity and diabetes. Using pharmacologic agents, we previously found that ~50% of these neurons responded to oleic acid (OA) by using the FA translocator/receptor FAT/CD36 (CD36). For further elucidation of the role of CD36 in neuronal FA sensing, ventromedial hypothalamus (VMH) CD36 was depleted using adeno-associated viral (AAV) vector expressing CD36 short hairpin RNA (shRNA) in rats. Whereas their neuronal glucosensing was unaffected by CD36 depletion, the percent of neurons that responded to OA was decreased specifically in glucosensing neurons. A similar effect was seen in total-body CD36-knockout mice. Next, weanling rats were injected in the VMH with CD36 AAV shRNA. Despite significant VMH CD36 depletion, there was no effect on food intake, body weight gain, or total carcass adiposity on chow or 45% fat diets. However, VMH CD36-depleted rats did have increased plasma leptin and subcutaneous fat deposition and markedly abnormal glucose tolerance. These results demonstrate that CD36 is a critical factor in both VMH neuronal FA sensing and the regulation of energy and glucose homeostasis.

  8. New Calix[4]arene dibenzocrown ethers for selective sensing of cesium ion in aqueous environment

    International Nuclear Information System (INIS)

    Kim, Jong Seung; Kim, Jong Kuk; Choi, Wang Kyu; Lee, Kune Woo; Oh, Won Jin

    1997-01-01

    1,3-dialkoxycalix[4]arene dibenzocrown ethers (6-9) were successfully synthesized in the fixed 1,3-alternate conformation with over 90% yields by the reaction of corresponding 1,3dialkoxycalix[4]arenes 2-5 with dibenzodimesylate 13 in acetonitrile as a solvent in the presence of cesium carbonate as a base. In view of cyclization yield, the use of dimesylate is found to be better than that of dibenzoditosylate. With an unusual AB pattern in 1 H NMR spectrum for compound 9, it is suggested that conformational structure of 1,3-diallyloxycalix[4]arene dibenzocrown ether be less flexible than that of usual 1,3-alternate calixcrown ether, probably due to steric effects of two ally1 group. Complexation of the corresponding calix[4]arene 6-9 toward alkali metal ions using single flux method through bulk liquid membrane system was found to give a high cesium selectivity. 28 refs., 1 tab., 1 fig

  9. Calcium Sensing by Recoverin: Effect of Protein Conformation on Ion Affinity.

    Science.gov (United States)

    Timr, Štěpán; Kadlec, Jan; Srb, Pavel; Ollila, O H Samuli; Jungwirth, Pavel

    2018-04-05

    The detailed functional mechanism of recoverin, which acts as a myristoyl switch at the rod outer-segment disk membrane, is elucidated by direct and replica-exchange molecular dynamics. In accord with NMR structural evidence and calcium binding assays, simulations point to the key role of enhanced calcium binding to the EF3 loop of the semiopen state of recoverin as compared to the closed state. This 2-4-order decrease in calcium dissociation constant stabilizes the semiopen state in response to the increase of cytosolic calcium concentration in the vicinity of recoverin. A second calcium ion then binds to the EF2 loop and, consequently, the structure of the protein changes from the semiopen to the open state. The latter has the myristoyl chain extruded to the cytosol, ready to act as a membrane anchor of recoverin.

  10. Zn2+ -Ion Sensing by Fluorescent Schiff Base Calix[4]arene Macrocycles.

    Science.gov (United States)

    Ullmann, Steve; Schnorr, René; Handke, Marcel; Laube, Christian; Abel, Bernd; Matysik, Jörg; Findeisen, Matthias; Rüger, Robert; Heine, Thomas; Kersting, Berthold

    2017-03-17

    A macrocyclic ligand (H 2 L) containing two o,o'-bis(iminomethyl)phenol and two calix[4]arene head units has been synthesized and its coordination chemistry towards divalent Ni and Zn investigated. The new macrocycle forms complexes of composition [ML] (M=Zn, M=Ni) and [ZnL(py) 2 ], which were characterized by elemental analysis; IR, UV/Vis, and NMR spectroscopy; electrospray ionization mass spectrometry (ESI-MS); and X-ray crystallography (for [ZnL(py) 2 ] and [NiL]). H 2 L allows the sensitive optical detection of Zn 2+ among a series of biologically relevant metal ions by a dual fluorescence enhancement/quenching effect in solution. The fluorescence intensity of the macrocycle increases by a factor of ten in the presence of Zn 2+ with a detection limit in the lower nanomolar region. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Effects of metal ions on biomass and 5-aminolevulinic acid production in Rhodopseudomonas palustris wastewater treatment.

    Science.gov (United States)

    Liu, Shuli; Zhang, Guangming; Li, Jianzheng; Li, Xiangkun; Zhang, Jie

    2016-01-01

    This work investigated the effects of eight metal ions on Rhodopseudomonas palustris growth and 5-aminolevulinic acid (ALA) yield in wastewater treatment. Results show that metal ions (Mg(2+) of 15 mmol/L, Fe(2+) of 400 μmol/L, Co(2+) of 4 μmol/L, Ni(2+) of 8 μmol/L and Zn(2+) of 4 μmol/L) could effectively improve the chemical oxygen demand (COD) removal, Rp. palustris biomass and ALA yield. The highest ALA yield of 13.1 mg/g-biomass was achieved with Fe(2+) of 400 μmol/L. ALA yields were differentially increased under different metal ions in the following order: Fe(2+) group > Mg(2+) group > Co(2+) group = Ni(2+) group > Zn(2+) group = Mo(2+) group > control. Cu(2+) and Mn(2+) inhibited Rp. palustris growth and ALA production. Mechanism analysis revealed that metal ions changed ALA yields by influencing the activities of ALA synthetase and ALA dehydratase.

  12. Responsiveness to acidity via metal ion regulators mediates virulence in the gastric pathogen Helicobacter pylori.

    Science.gov (United States)

    Bury-Moné, Stéphanie; Thiberge, Jean-Michel; Contreras, Monica; Maitournam, Aboubakar; Labigne, Agnès; De Reuse, Hilde

    2004-07-01

    The virulence of pathogenic bacteria is dependent on their adaptation to and survival in the stressful conditions encountered in their hosts. Helicobacter pylori exclusively colonizes the acid stomach of primates, making it an ideal study model. Little is known about how H. pylori responds to the moderately acidic conditions encountered at its colonization site, the gastric mucus layer. Thus, we compared gene expression profiles of H. pylori 26695 grown at neutral and acidic pH, and validated the data for a selection of genes by real-time polymerase chain reaction, dot-blots or enzymatic assays. During growth in acidic conditions, 56 genes were upregulated and 45 genes downregulated. We found that acidity is a signal modulating the expression of several virulence factors. Regulation of genes related to metal ion homeostasis suggests protective mechanisms involving diminished transport and enhanced storage. Genes encoding subunits of the F0F1 ATPase and of a newly identified Na+/H+ antiporter (NhaC-HP0946) were downregulated, revealing that this bacterium uses original mechanisms to control proton entry. Five of the upregulated genes encoded proteins controlling intracellular ammonia synthesis, including urease, amidase and formamidase, underlining the major role of this buffering compound in the protection against acidity in H. pylori. Regulatory networks and transcriptome analysis as well as enzymatic assays implicated two metal-responsive transcriptional regulators (NikR and Fur) and an essential two-component response regulator (HP0166, OmpR-like) as effectors of the H. pylori acid response. Finally, a nikR-fur mutant is attenuated in the mouse model, emphasizing the link between response to acidity, metal metabolism and virulence in this gastric pathogen.

  13. Negative Ion In-Source Decay Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry for Sequencing Acidic Peptides

    Science.gov (United States)

    McMillen, Chelsea L.; Wright, Patience M.; Cassady, Carolyn J.

    2016-05-01

    Matrix-assisted laser desorption/ionization (MALDI) in-source decay was studied in the negative ion mode on deprotonated peptides to determine its usefulness for obtaining extensive sequence information for acidic peptides. Eight biological acidic peptides, ranging in size from 11 to 33 residues, were studied by negative ion mode ISD (nISD). The matrices 2,5-dihydroxybenzoic acid, 2-aminobenzoic acid, 2-aminobenzamide, 1,5-diaminonaphthalene, 5-amino-1-naphthol, 3-aminoquinoline, and 9-aminoacridine were used with each peptide. Optimal fragmentation was produced with 1,5-diaminonphthalene (DAN), and extensive sequence informative fragmentation was observed for every peptide except hirudin(54-65). Cleavage at the N-Cα bond of the peptide backbone, producing c' and z' ions, was dominant for all peptides. Cleavage of the N-Cα bond N-terminal to proline residues was not observed. The formation of c and z ions is also found in electron transfer dissociation (ETD), electron capture dissociation (ECD), and positive ion mode ISD, which are considered to be radical-driven techniques. Oxidized insulin chain A, which has four highly acidic oxidized cysteine residues, had less extensive fragmentation. This peptide also exhibited the only charged localized fragmentation, with more pronounced product ion formation adjacent to the highly acidic residues. In addition, spectra were obtained by positive ion mode ISD for each protonated peptide; more sequence informative fragmentation was observed via nISD for all peptides. Three of the peptides studied had no product ion formation in ISD, but extensive sequence informative fragmentation was found in their nISD spectra. The results of this study indicate that nISD can be used to readily obtain sequence information for acidic peptides.

  14. Polymeric supported sorbents for decreasing hazardous metal ions content in wet process phosphoric acid

    International Nuclear Information System (INIS)

    El-Zahhar, A.A.; El-Naggar, H.A.; Ahmed, M.

    2005-01-01

    Procedure for preparation of polymeric supported silica, and their usage for decreasing hazardous metal ion content in wet process phosphoric acid was developed. The procedure is based firstly on extraction silica from rice straw by alkaline treatment , secondly supporting the produced silica on binding polyacrylonitrile (PAN). The produced polymer based sorbent was used for decreasing hazardous metal ions (especially iron) present as inorganic impurities in crud Egyptian phosphoric acid (green acid). Different factors affecting the sorption equilibrium ( contact time, temperature , sorbent mass and batch factor ) were studied. Studying the sorption isotherm revealed that the adsorption data could favorably fit the Langmuir adsorption isotherm. In the dynamic study , the sorption capacity at (Cξ/Cο = 50%) was found to be 28.5 mg/g and the loaded column could be regenerated using 50ml of 0.15 M HNO 3 . The regenerated column could undergo sorption regeneration cycles up to four cycles without significant decrease in the sorption capacity , weight loss or change in the physical properties of the sorbent

  15. Dose effects on damage of thymidylic acid and its components irradiated by A N+ ion beam

    International Nuclear Information System (INIS)

    Shao Chunlin; Yu Zengliang

    1996-08-01

    Research into damage of DNA components is an important field in mechanism study to the low energy ion beam irradiation. It was found that the UV difference spectra of irradiated thymine (T) had two positive peaks caused by the changes of π electron conjugation of the pyrimidine ring, and that the residual activity of T sample irradiated by a N + ion beam was not influenced by treatments of acid and alkali as well as heat. In addition, the residual activities of irradiated thymidine (dTR) and thymidine 5'-phosphate (5'-dTMP) with and without treating of strong acid and strong alkali were also measured. With UV absorption spectrophotometry, the yield of T released from the irradiated samples of dTR and 5'-dTMP and the residual concentration of these target molecules were deduced, and it was found that the yield of T increased when the solution of the irradiated dTR sample was treated by heat but decreased when this solution was treated by acid and alkali for these treatments splitting T-S or T-S-P. On the other hand, the yield of inorganic phosphate released from the irradiated 5'-dTMP was investigated and found that it was increased by the treatment of alkali and that the increase degree was depended on the time scale of the treatment. Moreover, G(Pi) of the irradiated 5'-dTMP non-linearly decreased with increasing dose. (10 figs.)

  16. Adsorption of uranium ions by crosslinked polyester resin functionalized with acrylic acid from aqueous solutions

    International Nuclear Information System (INIS)

    Cemal Oezeroglu; Niluefer Metin

    2012-01-01

    In this paper, the crosslinked polyester resin containing acrylic acid functional groups was used for the adsorption of uranium ions from aqueous solutions. For this purpose, the crosslinked polyester resin of unsaturated polyester in styrene monomer (Polipol 353, Poliya) and acrylic acid as weight percentage at 80 and 20%, respectively was synthesized by using methyl ethyl ketone peroxide (MEKp, Butanox M60, Azo Nobel)-cobalt octoate initiator system. The adsorption of uranium ions on the sample (0.05 g copolymer and 5 mL of U(VI) solution were mixed) of the crosslinked polyester resin functionalized with acrylic acid was carried out in a batch reactor. The effects of adsorption parameters of the contact time, temperature, pH of solution and initial uranium(VI) concentration for U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid were investigated. The adsorption data obtained from experimental results depending on the initial U(VI) concentration were analyzed by the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The adsorption capacity and free energy change were determined by using D-R isotherm. The obtained experimental adsorption data depending on temperature were evaluated to calculate the thermodynamic parameters of enthalpy (ΔH o ), entropy (ΔS o ) and free energy change (ΔG o ) for the U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid from aqueous solutions. The obtained adsorption data depending on contact time were analyzed by using adsorption models such as the modified Freundlich, Elovich, pseudo-first order and pseudo-second-order kinetic models. (author)

  17. Separation of metal ions by anion exchange in mixtures of hydrochloric acid and hydrofluoric acid

    International Nuclear Information System (INIS)

    Faris, J.P.

    1978-12-01

    Distribution coefficients were determined for the adsorption of more than 40 elements on anion-exchange resins from mixtures of HCl (0.1 to 12M) and HF (0.1-8M). Two resins, Dowex 1 x 10, 200 to 400 mesh and Dowex 1 x 4, 100 to 200 mesh, were used. Distribution coefficients were also determined for the adsorption of many elements on both resins from 0.1 to 12M HCl and 0.1 to 12M HF. Anion exchange in the presence of HF was found useful for separating impurities from various materials for their subsequent determination, and specific procedures used in our spectrochemical laboratory for this purpose are outlined. The results of a literature search on the use of anion exchange in hydrofluoric acid and fluoride-containing media are presented in an extensive bibliography. 404 references, 9 tables

  18. Preparation of poly(acrylic acid)-chitosan hydrogels by gamma irradiation for metal ions sorption

    International Nuclear Information System (INIS)

    Tran Thu Hong; Le Hai; Nguyen Tan Man; Tran Thi Tam; Pham Thi Le Ha; Pham Thi Sam; Nguyen Duy Hang; Le Huu Tu; Le Van Toan

    2013-01-01

    Acid acrylic (AAc) was grafted onto crosslinked chitosan to make Chitosan-g-AAc copolymer with concentration of AAc from 0.5 to 15% by gamma irradiation. The optimal dose for grafting of 15% AAc onto chitosan was 5 kGy. Physical and chemical properties of irradiated samples such as SEM images, FTIR spectroscopy, TGA and swelling behavior at different pHs were evaluated. The grafting yield increased with the increase in dose, it reached 52% at 7 kGy irradiation dose. The application were grafted materials to adsorb metals ion from aqueous solutions was also investigated with both ungrafted and grafted chitosan beads under changing pH from 3 to 6. Grafted chitosan presented higher sorption capacity for most of metal ions than unmodified chitosan. (author)

  19. Grafting of acrylic acid onto polypropylene films irradiated with argon ions

    International Nuclear Information System (INIS)

    Massa, G.; Mazzei, R.; Garcia Bermudez, G.; Filevich, A.; Smolko, E.

    2005-01-01

    Polypropylene (PP) foils were irradiated with 100 keV energy Argon ions at different fluences ranging from 10 12 up to 2 x 10 15 cm -2 and then grafted with acrylic acid (AA). The grafting yield was measured by weight difference and the structural changes on the films were analysed using Fourier transform infrared spectroscopy (FTIR). Different parameters that determined the grafting process such us fluence, grafting time and monomer concentration were analysed. The grafting reached an optimum value at 79% in aqueous solution at 30 min grafting time. The grafting yield as a function of the ion fluence plot, presented a maximum value, as previously found in a study of heavy beam on polymers

  20. PAN-Immobilized PVC-NPOE Membrane for Environmentally Friendly Sensing of Cd(II Ions

    Directory of Open Access Journals (Sweden)

    Moersilah Moersilah

    2017-04-01

    Full Text Available A simple, cheap and environmentally friendly analytical method of Cd(II in the aqueous system has been developed by immobilization of 1-(2-pyridilazo-2-naphtol (PAN in poly vinyl chloride (PVC matrix and nitrophenyl octyl ether (NPOE as a plasticizer. Upon contact with Cd(II in solution, the color of sensor membrane changes from dark yellow to dark red, which is due to the formation of Cd(II–PAN complex. The best sensing results were obtained at pH 8.0 and λmax 558 nm. The dimension of the proposed sensor membrane was 0.8 cm x 2 cm with a thickness of 0.05 mm, the volume of sample was 2 mL with the Cd(II concentration range of  0 – 1.2 ppm. The limit of detection of the method was found to be 0.432 + 0.104 ppm, which was reversible. The proposed methods have been applied in the determination of Cd(II in water samples after addition of internal standard.

  1. Acid-sensing ion channels in rat hypothalamic vasopressin neurons of the supraoptic nucleus

    Czech Academy of Sciences Publication Activity Database

    Ohbuchi, T.; Sato, K.; Suzuki, H.; Okada, Y.; Dayanithi, Govindan; Murphy, D.; Ueta, Y.

    2010-01-01

    Roč. 588, č. 12 (2010), s. 2147-2162 ISSN 0022-3751 Institutional research plan: CEZ:AV0Z50390703 Keywords : hypothalamus * ASIC * oxytocin Subject RIV: FH - Neurology Impact factor: 5.139, year: 2010

  2. Molecular Basis for Allosteric Inhibition of Acid-Sensing Ion Channel 1a by Ibuprofen

    DEFF Research Database (Denmark)

    Lynagh, Timothy; Romero-Rojo, José Luis; Lund, Camilla

    2017-01-01

    -clamp fluorometry. Our results show that ibuprofen is an allosteric inhibitor of ASIC1a, which binds to a crucial site in the agonist transduction pathway and causes conformational changes that oppose channel activation. Ibuprofen inhibits several ASIC subtypes, but certain ibuprofen derivatives show some...

  3. Acidosis counteracts itch tachyphylaxis to consecutive pruritogen exposure dependent on acid-sensing ion channel 3

    OpenAIRE

    Jiang, Yi-Ming; Huang, Chen; Peng, Zhong; Han, Shao-Ling; Li, Wei-Guang; Zhu, Michael Xi; Xu, Tian-Le

    2017-01-01

    Tachyphylaxis of itch refers to a markedly reduced scratching response to consecutive exposures of a pruritogen, a process thought to protect against tissue damage by incessant scratching and to become disrupted in chronic itch. Here, we report that a strong stimulation of the Mas-related G-protein-coupled receptor C11 by its agonist, Ser-Leu-Ile-Gly-Arg-Leu-NH2 (SL-NH2) or bovine adrenal medulla 8-22 peptide, via subcutaneous injection in mice induces tachyphylaxis to the subsequent applicat...

  4. Dissolution of oxalate precipitate and destruction of oxalate ion by hydrogen peroxide in nitric acid solution

    International Nuclear Information System (INIS)

    Kim, Eung-Ho; Chung, Dong-Yong; Park, Jin-Ho; Yoo, Jae-Hyung

    2000-01-01

    This study aims at developing an oxalate precipitation process, which is applicable to a partitioning of long-lived radionuclides from the high-level radioactive liquid waste. In order to achieve this, a study for decomposition-reaction of oxalic acid by hydrogen peroxide was first carried out. The decomposition rates of H 2 O 2 and oxalic acid increased with an increase of nitric acid concentration, and especially those decomposition rates steeply increased at more than 2 M HNO 3 . Based on this result, the decomposition kinetics of H 2 O 2 and oxalic acid were suggested in this work. Then, the dissolution of oxalate precipitate and the destruction of oxalate ion in the solution were examined. Oxalate precipitates were prepared by adding oxalic acid into a simulated radioactive waste containing 8 metallic elements. The precipitates obtained thereby were dissolved in various nitric acid concentrations and reacted with H 2 O 2 at 90degC. When the oxalates were completely dissolved, most of the oxalates were decomposed by adding H 2 O 2 , but in a slurry state the decomposition yield of the oxalate decreased with an increase of the slurry density in the solution. Such phenomenon was considered to be due to a catalytic decomposition of H 2 O 2 on a solid surface of oxalate and the decomposition mechanism was explained by a charge transfer from a surface of oxalate solid to H 2 O 2 , producing OH radicals which can destruct H 2 O 2 explosively. Accordingly, the experimental condition for the decomposition of the oxalate precipitates was found to be most favorable at 3 M HNO 3 under the initial concentrations of 0.2 M oxalate and 1 M H 2 O 2 . At 3M HNO 3 , oxalate precipitates could be safely and completely dissolved, and almost decomposed. Additionally, it was observed that the presence of ferric ion in the solution largely affects the decomposition rate of H 2 O 2 . This could be explained by a chain reaction of hydrogen peroxide with ferric ion in the solution

  5. Hydrometallurgical recovery of metal values from sulfuric acid leaching liquor of spent lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiangping; Chen, Yongbin; Zhou, Tao, E-mail: zhoutao@csu.edu.cn; Liu, Depei; Hu, Hang; Fan, Shaoyun

    2015-04-15

    Highlights: • Selective precipitation and solvent extraction were adopted. • Nickel, cobalt and lithium were selectively precipitated. • Co-D2EHPA was employed as high-efficiency extraction reagent for manganese. • High recovery percentages could be achieved for all metal values. - Abstract: Environmentally hazardous substances contained in spent Li-ion batteries, such as heavy metals and nocuous organics, will pose a threat to the environment and human health. On the other hand, the sustainable recycling of spent lithium-ion batteries may bring about environmental and economic benefits. In this study, a hydrometallurgical process was adopted for the comprehensive recovery of nickel, manganese, cobalt and lithium from sulfuric acid leaching liquor from waste cathode materials of spent lithium-ion batteries. First, nickel ions were selectively precipitated and recovered using dimethylglyoxime reagent. Recycled dimethylglyoxime could be re-used as precipitant for nickel and revealed similar precipitation performance compared with fresh dimethylglyoxime. Then the separation of manganese and cobalt was conducted by solvent extraction method using cobalt loaded D2EHPA. And McCabe–Thiele isotherm was employed for the prediction of the degree of separation and the number of extraction stages needed at specific experimental conditions. Finally, cobalt and lithium were sequentially precipitated and recovered as CoC{sub 2}O{sub 4}⋅2H{sub 2}O and Li{sub 2}CO{sub 3} using ammonium oxalate solution and saturated sodium carbonate solution, respectively. Recovery efficiencies could be attained as follows: 98.7% for Ni; 97.1% for Mn, 98.2% for Co and 81.0% for Li under optimized experimental conditions. This hydrometallurgical process may promise a candidate for the effective separation and recovery of metal values from the sulfuric acid leaching liquor.

  6. Hydrometallurgical recovery of metal values from sulfuric acid leaching liquor of spent lithium-ion batteries

    International Nuclear Information System (INIS)

    Chen, Xiangping; Chen, Yongbin; Zhou, Tao; Liu, Depei; Hu, Hang; Fan, Shaoyun

    2015-01-01

    Highlights: • Selective precipitation and solvent extraction were adopted. • Nickel, cobalt and lithium were selectively precipitated. • Co-D2EHPA was employed as high-efficiency extraction reagent for manganese. • High recovery percentages could be achieved for all metal values. - Abstract: Environmentally hazardous substances contained in spent Li-ion batteries, such as heavy metals and nocuous organics, will pose a threat to the environment and human health. On the other hand, the sustainable recycling of spent lithium-ion batteries may bring about environmental and economic benefits. In this study, a hydrometallurgical process was adopted for the comprehensive recovery of nickel, manganese, cobalt and lithium from sulfuric acid leaching liquor from waste cathode materials of spent lithium-ion batteries. First, nickel ions were selectively precipitated and recovered using dimethylglyoxime reagent. Recycled dimethylglyoxime could be re-used as precipitant for nickel and revealed similar precipitation performance compared with fresh dimethylglyoxime. Then the separation of manganese and cobalt was conducted by solvent extraction method using cobalt loaded D2EHPA. And McCabe–Thiele isotherm was employed for the prediction of the degree of separation and the number of extraction stages needed at specific experimental conditions. Finally, cobalt and lithium were sequentially precipitated and recovered as CoC 2 O 4 ⋅2H 2 O and Li 2 CO 3 using ammonium oxalate solution and saturated sodium carbonate solution, respectively. Recovery efficiencies could be attained as follows: 98.7% for Ni; 97.1% for Mn, 98.2% for Co and 81.0% for Li under optimized experimental conditions. This hydrometallurgical process may promise a candidate for the effective separation and recovery of metal values from the sulfuric acid leaching liquor

  7. Graphene/Gold Nano composites-Based Thin Films as an Enhanced Sensing Platform for Voltammetric Detection of Cr(VI) Ions

    International Nuclear Information System (INIS)

    Santhosh, Ch.; Saranya, M.; Ramachandran, R.; Felix, S.; Velmurugan, V.; Grace, A.N.

    2014-01-01

    A highly sensitive and selective Cr(VI) sensor with graphene-based nano composites film as an enhanced sensing platform is reported. The detection of chromium species is a challenging task because of the different possible oxidation states in which the element can occur. The sensing film was developed by homogeneously distributing Au nanoparticles (AuNPs) onto the two-dimensional (2D) graphene nano sheet matrix by electrochemical method. Such nano structured composite film platforms combine the advantages of AuNPs and graph ene nano sheets because of the synergistic effect between them. This effect greatly facilitates the electron-transfer processes and the sensing behavior for Cr(VI) detection, leading to a remarkably improved sensitivity and selectivity. The interference from other heavy metal ions is studied in detail. Such sensing elements are very promising for practical environmental monitoring applications.

  8. Oxidative degradation of ion-exchange resins in acid medium. Vol. 3

    International Nuclear Information System (INIS)

    Eskander, S.B.; Ghattas, N.K.

    1996-01-01

    Volume reduction of spent ion-exchange resins used in nuclear facilities receive increasing importance due to the increase in storage cost, unstable physical and chemical properties and their relatively high specific activity (in some cases up to 1 Ci per liter). The present study is part of research program on the treatment and immobilization of radioactive spent ion-exchange resins simulate; hydrogen peroxide was used for the oxidative degradation of spent ion-exchange resins simulate in sulphuric acid medium. Five liters ring digester developed in Karlsruhe nuclear research center-(KFK)- in germany was the chosen option to perform the oxidation process. The work reported focused on the kinetics and mechanism of the oxidation process. Heating the organic resins in sulphuric acid results in its carbonization and partial oxidation of only 1.7% of the carbon added. Results show that the oxidation reaction is a relatively slow process of first order with K value in the order of 10 -4 min -1 , and the main oxidation product was carbon dioxide. The production of carbon oxide in the off gas stream increased sharply by the addition of hydrogen peroxide to the hot sulphuric acid-resin mixture. The results obtained show that more than 97% of the carbon added was oxidized to carbon dioxide and carbon monoxide. The rate constant value (K) of this reaction was calculated to be (1.69±0.13) x 10 -2 min -1 . The results of gas chromatographic analysis indicate that no significant amounts of hazardous organic materials were detected in the off-gas streams. 6 figs., 4 tabs

  9. Regioisomers of octanoic acid-containing structured triacylglycerols analyzed by tandem mass spectrometry using ammonia negative ion chemical ionization

    DEFF Research Database (Denmark)

    Kurvinen, J.P.; Mu, Huiling; Kallio, H.

    2001-01-01

    Tandem mass spectrometry based on ammonia negative ion chemical ionization and sample introduction via direct exposure probe was applied to analysis of regioisomeric structures of octanoic acid containing structured triacylglycerols (TAG) of type MML, MLM, MLL, and LML (M, medium-chain fatty acid...

  10. Studies on Pu(IV)/(III)-oxalate precipitation from nitric acid containing high concentration of calcium and fluoride ions

    International Nuclear Information System (INIS)

    Kalsi, P.K.; Pawar, S.M.; Ghadse, D.R.; Joshi, A.R.; Ramakrishna, V.V.; Vaidya, V.N.; Venugopal, V.

    2003-01-01

    Plutonium (IV)/(III) oxalate precipitation from nitric acid solution, containing large amount of calcium and fluoride ions was investigated. It was observed that direct precipitation of Pu (IV) oxalate from nitric acid containing large amount of calcium and fluoride ions did not give good decontamination of Pu from calcium and fluoride impurities. However, incorporation of hydroxide precipitation using ammonium hydroxide prior to Pu (IV) oxalate precipitation results into PuO 2 with much less calcium and fluoride impurities. Whereas, good decontamination from calcium and fluoride impurities could be obtained by employing Pu (III) oxalate precipitation directly from nitric acid containing large amount of calcium and fluoride ions. A method was also developed to recover Pu from the oxalate waste containing calcium and fluoride ions. (author)

  11. A facile method to prepare fluorescent carbon dots and their application in selective colorimetric sensing of silver ion through the formation of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ayaz Ahmed, Khan Behlol; P, Suresh Kumar; Veerappan, Anbazhagan, E-mail: anbazhagan@scbt.sastra.edu

    2016-09-15

    Herein, we report a laboratory convenient method for the preparation of blue color emitting fluorescent carbon dots (C-dots) in 60 min by boiling the alkaline solution of pectin. The C-dots derived from pectin detects selectively silver ion by forming silver nanoparticles (AgNPs) without any irradiation or heating or additional reducing agents. As prepared AgNPs appears yellow in color and showed the characteristic surface plasmon resonance maximum at 410 nm. Transmission electron microscopy (TEM) revealed crystalline, spherical AgNPs with size range from 10–15 nm. Cyclic voltammetry study revealed that the lower reduction potential of C-dots than that of silver ion favors the reduction of Ag{sup +} to Ag°. Electrochemical impedance spectroscopy showed the charge transfer value for the redox reaction of C-dots as 200 Ωcm{sup 2}. In the presence of Ag{sup +}, C-dots fluorescence emission was turned from blue to cyan to green to colorless, accompanying the quenching and red shift in emission maximum at 450 nm. Interference study clearly showed that the C-dots have high preference for Ag{sup +} ion than the other interfering metal ions. The proposed sensor system selectively senses Ag{sup +} ion in water at micromolar concentration and also offers an easy procedure to prepare AgNPs in the presence of other interfering metal ions. - Highlights: • Blue color emitting C-dots was prepared by boiling alkaline pectin solution. • C-dots sense silver ion at micromolar concentration. • C-dots recognize silver ion in the presence of interfering metal ions. • Reduction potential of C-dots was estimated by cyclic voltammeter as – 0.2 V.

  12. Formation of Amino Acid Precursors by Bombardment of Interstellar Ice Analogs with High Energy Heavy Ions

    Science.gov (United States)

    Kobayashi, Kensei; Mita, Hajime; Yoshida, Satoshi; Shibata, Hiromi; Enomoto, Shingo; Matsuda, Tomoyuki; Fukuda, Hitoshi; Kondo, Kotaro; Oguri, Yoshiyuki; Kebukawa, Yoko

    2016-07-01

    A wide variety of organic compounds have been detected in extraterrestrial bodies. It has been recognized that carbonaceous chondrites contain pristine amino acids [1]. There are several scenarios of the formation of such extraterrestrial amino acids or their precursors. Greenberg proposed a scenario that complex organic compounds were formed in interstellar ices in dense clouds, which were brought into solar system small bodies when the solar system was formed [2]. The ice mantles of interstellar dust particles (ISDs) in dense clouds are composed of H2O, CO, CH3OH, CH4, CO2, NH3, etc. In order to verify the scenario, a number of laboratory experiments have been conducted where interstellar ice analogs were irradiated with high-energy particles [3,4] or UV [5,6], and formation of complex organic compounds including amino acid precursors were detected in the products. Though ion-molecular reactions in gaseous phase and surface reactions on the ice mantles have been studied intensively, much less works on cosmic rays-induced reaction have been reported. In order to study possible formation of complex molecules in interstellar ices, frozen mixtures of water, methanol and ammonia with various mixing ratios were irradiated with high-energy heavy ions such as carbon ions (290 MeV/u) and neon ions (400 MeV/u) from HIMAC, NIRS, Japan. For comparison, gaseous mixtures of water, ammonia, carbon monoxide, carbon dioxide, and/or methane were irradiated with protons (2.5 MeV) from a Tandem accelerator, Tokyo Tech, Japan. Amino acids in the products were determined by cation exchange HPLC after acid hydrolysis. Products, both before and after acid hydrolysis, were also characterized by FT-IR and other techniques. Amino acids were detected in the hydrolyzed products after mixture of CH3OH, NH3 and H2O with various mixing ratios were irradiated with heavy ions, including when their mixing ratio was set close to the reported value of the interstellar ices (10:1:37). In the HIMAC

  13. Functionalization of mesoporous silica membrane with a Schiff base fluorophore for Cu(II) ion sensing

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xiaotong [Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku 980-8578, Sendai, Miyagi Prefecture (Japan); Department of Chemistry, Tsinghua University, Beijing 100084 (China); Yamaguchi, Akira [College of Science, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki 310-8512 (Japan); Frontier Research Center for Applied Atomic Sciences, Ibaraki University, Tokai, Ibaraki 319-1106 (Japan); Namekawa, Manato [Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku 980-8578, Sendai, Miyagi Prefecture (Japan); Kamijo, Toshio [Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku 980-8578, Sendai, Miyagi Prefecture (Japan); Tsuruoka National College of Technology, Aza-Sawada, Tsuruoka 997-8511 (Japan); Teramae, Norio, E-mail: teramae@m.tohoku.ac.jp [Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku 980-8578, Sendai, Miyagi Prefecture (Japan); Tong, Aijun, E-mail: tongaj@mail.tsinghua.edu.cn [Department of Chemistry, Tsinghua University, Beijing 100084 (China)

    2011-06-24

    Graphical abstract: Highlights: > A hybrid mesoporous membrane (SB-HMM) functionalized by Schiff base fluorophores was fabricated. > SB-HMM showed strong fluorescence with aggregation-induced emission enhancement properties. > SB-HMM was applicable for the detection of Cu(II) in an aqueous solution with good reversibility and reproducibility. - Abstract: A Schiff base (SB) immobilized hybrid mesoporous silica membrane (SB-HMM) was prepared by immobilizing a Schiff base onto the pore surface of mesoporous silica (pore size = 3.1 nm) embedded in the pores of a porous anodic alumina membrane. In contrast to the non-fluorescent analogous SB molecule in homogeneous solutions, SB-HMM exhibited intense fluorescence due to emission enhancement caused by aggregation of SB groups on the pore surface. The high quantum efficiency of the surface SB groups allows SB-HMM to function as a fluorescent sensor for Cu(II) ions in an aqueous solution with good sensitivity, selectivity and reproducibility. Under the optimal conditions described, the linear ranges of fluorescence intensity for Cu(II) are 1.2-13.8 (M (R{sup 2} = 0.993) and 19.4-60 (R{sup 2} = 0.992) (M. The limit of detection for Cu(II) is 0.8 {mu}M on basis of the definition by IUPAC (C{sub LOD} = 3.3S{sub b}/m).

  14. New Calix[4]arene dibenzocrown ethers for selective sensing of cesium ion in aqueous environment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Seung; Kim, Jong Kuk [Konyang University, Nonsan (Korea, Republic of); Choi, Wang Kyu; Lee, Kune Woo; Oh, Won Jin [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    1,3-dialkoxycalix[4]arene dibenzocrown ethers (6-9) were successfully synthesized in the fixed 1,3-alternate conformation with over 90% yields by the reaction of corresponding 1,3dialkoxycalix[4]arenes 2-5 with dibenzodimesylate 13 in acetonitrile as a solvent in the presence of cesium carbonate as a base. In view of cyclization yield, the use of dimesylate is found to be better than that of dibenzoditosylate. With an unusual AB pattern in {sup 1}H NMR spectrum for compound 9, it is suggested that conformational structure of 1,3-diallyloxycalix[4]arene dibenzocrown ether be less flexible than that of usual 1,3-alternate calixcrown ether, probably due to steric effects of two ally1 group. Complexation of the corresponding calix[4]arene 6-9 toward alkali metal ions using single flux method through bulk liquid membrane system was found to give a high cesium selectivity. 28 refs., 1 tab., 1 fig.

  15. Chromatographic retention prediction and octanol-water partition coefficient determination of monobasic weak acidic compounds in ion-suppression reversed-phase liquid chromatography using acids as ion-suppressors.

    Science.gov (United States)

    Ming, Xin; Han, Shu-ying; Qi, Zheng-chun; Sheng, Dong; Lian, Hong-zhen

    2009-08-15

    Although simple acids, replacing buffers, have been widely applied to suppress the ionization of weakly ionizable acidic analytes in reversed-phase liquid chromatography (RPLC), none of the previously reported works focused on the systematic studies about the retention behavior of the acidic solutes in this ion-suppression RPLC mode. The subject of this paper was therefore to investigate the retention behavior of monobasic weak acidic compounds using acetic, perchloric and phosphoric acids as the ion-suppressors. The apparent octanol-water partition coefficient (K" ow) was proposed to calibrate the octanol-water partition coefficient (K(ow)) of these weak acidic compounds, which resulted in a better linear correlation with log k(w), the logarithm of the hypothetical retention factor corresponding to neat aqueous fraction of hydroorganic mobile phase. This log K" ow-log k w linear correlation was successfully validated by the results of monocarboxylic acids and monohydrating phenols, and moreover by the results under diverse experimental conditions for the same solutes. This straightforward relationship not only can be used to effectively predict the retention values of weak acidic solutes combined with Snyder-Soczewinski equation, but also can offer a promising medium for directly measuring K(ow) data of these compounds via Collander equation. In addition, the influence of the different ion-suppressors on the retention of weak acidic compounds was also compared in this RPLC mode.

  16. Distinguishing d- and l-aspartic and isoaspartic acids in amyloid β peptides with ultrahigh resolution ion mobility spectrometry.

    Science.gov (United States)

    Zheng, Xueyun; Deng, Liulin; Baker, Erin S; Ibrahim, Yehia M; Petyuk, Vladislav A; Smith, Richard D

    2017-07-11

    While α-linked amino acids in the l-form are exclusively utilized in mammalian protein building, β-linked and d-form amino acids also have important biological roles. Unfortunately, the structural elucidation and separation of these different amino acid types in peptides has been analytically challenging to date due to the numerous isomers present, limiting our knowledge about their existence and biological roles. Here, we utilized an ultrahigh resolution ion mobility spectrometry platform coupled with mass spectrometry (IMS-MS) to separate amyloid β (Aβ) peptides containing l-aspartic acid, d-aspartic acid, l-isoaspartic acid, and d-isoaspartic acid residues which span α- and β-linked amino acids in both d- and l-forms. The results illustrate how IMS-MS could be used to better understand age-related diseases or protein folding disorders resulting from amino acid modifications.

  17. Experimental particle formation rates spanning tropospheric sulfuric acid and ammonia abundances, ion production rates, and temperatures

    CERN Document Server

    Kürten, Andreas; Almeida, Joao; Kupiainen-Määttä, Oona; Dunne, Eimear M.; Duplissy, Jonathan; Williamson, Christina; Barmet, Peter; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M.; Flagan, Richard C.; Franchin, Alessandro; Gordon, Hamish; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Ickes, Luisa; Jokinen, Tuija; Kangasluoma, Juha; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Onnela, Antti; Ortega, Ismael K.; Petäjä, Tuukka; Praplan, Arnaud P.; Riccobono, Francesco; Rissanen, Matti P.; Rondo, Linda; Schnitzhofer, Ralf; Schobesberger, Siegfried; Smith, James N.; Steiner, Gerhard; Stozhkov, Yuri; Tomé, António; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Wagner, Paul E.; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Ken; Kulmala, Markku; Curtius, Joachim

    2016-01-01

    Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia arethought to be the dominant processes responsible for new particle formation (NPF) in the cold temperaturesof the middle and upper troposphere. Ions are also thought to be important for particle nucleation inthese regions. However, global models presently lack experimentally measured NPF rates under controlledlaboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here withdata obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets)chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. Theconditions during nucleation cover a temperature range from 208 to 298 K, sulfuric acid concentrationsbet ween 5 × 105and 1 × 109cm3, and ammonia mixing ratios from zero added ammonia, i.e., nominally purebinary, to a maximum of ~1400 parts per trillion by volume (pptv). We performed nucleation s...

  18. Ion flotation of uranium contained in industrial phosphoric acid with collector recycling

    International Nuclear Information System (INIS)

    Jdid, E.; Blazy, P.; Bessiere, J.

    1985-01-01

    Uranium has been recovered from wet-process phosphoric acid (30% P 2 O 5 ) by ion flotation with an anionic organophosphorous collector. Recoveries greater than 90% were obtained even at temperatures of about 60 C, the uranium concentrate, which was collected in the froth as a precipitate, containing 7 to 10% U. Collector consumption without recycling of the surface-active reagent was about 12 kg/kg U. Much of the reagent, however, can be recovered for recycling by attack with sodium hydroxide on the floated phase after filtration. This enables a precipitate containing about 30% U to be produced and decreases collector consumption to about 3 kg/kg U. The results were obtained in laboratory-scale experiments on industrial wet-process acid. (author)

  19. Extraction of trivalent actinides and lanthanides from nitric acid solutions by ion flotation

    International Nuclear Information System (INIS)

    Mezhov, E.H.; Samatov, A.V.; Troyanovskiy, L.V.

    1992-01-01

    To determine whether the deep extraction of trivalent actinides from liquid active waste is feasible, the authors made a detailed investigation into the ion flotation of europium (as a simulator of americium) and americium from nitric acid solutions by using as an SAS precipitant either lauril phosphoric acid (LPA) to reprocess 0.1-0.7 M HNO 3 or diphosphine dioxides (PO) for 1-5 M HNO 3 . In all instances the extent of metal removal increases with floto-reagent expenditure. When the floto-reagent excess required for full precipitation is reached, the extraction of the metals under study is high, viz., 97-98% from 0.1 M HNO 3 with LPA and ∼75% from 3-3.5 M HNO 3 with PO per one flotation operation

  20. Effect of fluoride on ion exchange, remineralization and acid resistance of surface enamel

    Energy Technology Data Exchange (ETDEWEB)

    Aponte-Merced, L A; Feagin, F F [Alabama Univ., Birmingham (USA)

    1979-01-01

    In a system of constant ion activities the rates of F/sup -/ exchange in enamel, under conditions of exchange alone and remineralization, depended on the concentration of F/sup -/ in solutions. Acid resistance of surface minerals resulted from exchange of F/sup -/ for OH/sup -/ in the enamel at pH 7.0 and 4.5. The level of 0.5 mM NaF, compared to 0.05 and 5.0 mM, caused maximum rates of isotopic exchange of /sup 45/Ca and maximum acid resistance of enamel. Similarly low levels of F/sup -/ may be feasible for use in caries prevention in the absence and presence of remineralization.

  1. Ultraefficient separation and sensing of mercury and methylmercury ions in drinking water by using aminonaphthalimide-functionalized Fe(3)O(4)@SiO(2) core/shell magnetic nanoparticles.

    Science.gov (United States)

    Park, Minsung; Seo, Sungmin; Lee, In Su; Jung, Jong Hwa

    2010-07-07

    A new fluorogenic based aminonaphthalimide-functionalized Fe(3)O(4)@SiO(2) core/shell magnetic nanoparticles 1 has been prepared, and its abilities to sense and separate metal ions were evaluated by fluorophotometry. The nanoparticles 1 exhibited a high affinity and selectivity for Hg(2+) and CH(3)Hg(+) ions over competing metal ions.

  2. Determination of anions in pure and commercial phosphoric acid by ion chromatography and manual of 792 basic IC

    International Nuclear Information System (INIS)

    Al-Kabani, F.; Abdulbaki, M. K.

    2007-01-01

    A method for determination of anions in pure and concentrated phosphoric and samples (85%) and commercial phosphoric acid ion chromatography was developed, in order to control the specification of phosphoric acid produced in the pilot plant for phosphoric acid purification. The accuracy of the method was studied and the standard deviation was found to be between 0.09 and 0.10. Operation instructions of 792 Basic IC was described. (author)

  3. Acid-base and ion balance in fishes with bimodal respiration.

    Science.gov (United States)

    Shartau, R B; Brauner, C J

    2014-03-01

    The evolution of air breathing during the Devonian provided early fishes with bimodal respiration with a stable O2 supply from air. This was, however, probably associated with challenges and trade-offs in terms of acid-base balance and ionoregulation due to reduced gill:water interaction and changes in gill morphology associated with air breathing. While many aspects of acid-base and ionoregulation in air-breathing fishes are similar to water breathers, the specific cellular and molecular mechanisms involved remain largely unstudied. In general, reduced ionic permeability appears to be an important adaptation in the few bimodal fishes investigated but it is not known if this is a general characteristic. The kidney appears to play an important role in minimizing ion loss to the freshwater environment in the few species investigated, and while ion uptake across the gut is probably important, it has been largely unexplored. In general, air breathing in facultative air-breathing fishes is associated with an acid-base disturbance, resulting in an increased partial pressure of arterial CO2 and a reduction in extracellular pH (pHE ); however, several fishes appear to be capable of tightly regulating tissue intracellular pH (pHI ), despite a large sustained reduction in pHE , a trait termed preferential pHI regulation. Further studies are needed to determine whether preferential pHI regulation is a general trait among bimodal fishes and if this confers reduced sensitivity to acid-base disturbances, including those induced by hypercarbia, exhaustive exercise and hypoxia or anoxia. Additionally, elucidating the cellular and molecular mechanisms may yield insight into whether preferential pHI regulation is a trait ultimately associated with the early evolution of air breathing in vertebrates. © 2014 The Fisheries Society of the British Isles.

  4. Specifically colorimetric recognition of calcium, strontium, and barium ions using 2-mercaptosuccinic acid-functionalized gold nanoparticles and its use in reliable detection of calcium ion in water.

    Science.gov (United States)

    Zhang, Jia; Wang, Yong; Xu, Xiaowen; Yang, Xiurong

    2011-10-07

    A colorimetric probe based on 2-mercaptosuccinic acid-functionalized gold nanoparticles has been developed to exhibit selectivity towards Ca(2+), Sr(2+), and Ba(2+) ions over other metallic cations under specified conditions and finds its practical application in detecting Ca(2+) levels in water.

  5. Biosynthesis of nano cupric oxide on cotton using Seidlitzia rosmarinus ashes utilizing bio, photo, acid sensing and leaching properties.

    Science.gov (United States)

    Bashiri Rezaie, Ali; Montazer, Majid; Rad, Mahnaz Mahmoudi

    2017-12-01

    In this research, a facile, rapid and eco-friendly method is introduced for synthesis and loading of cupric oxide on cellulosic chains of cotton fabric with functional properties. Seidlitzia rosmarinus ashes and copper acetate were employed as a natural source of alkaline and metal salt without further chemical materials. The treated samples indicated very good antibacterial activities toward both pathogen Staphylococcus aureus as Gram-positive and Escherichia coli as Gram-negative bacteria. Significant self-cleaning properties against degradation of methylene blue stain under UV irradiation were found. The sensing properties of high concentrated inorganic and organic acids such as sulfuric and formic acids based on colorimetric alterations of the treated fabrics were also confirmed showing acid leaching effects of the treated fabrics. Further, the treated samples showed coloring effects with an enhancement on the physio-mechanical properties including tensile strength, crease recovery angle and hydrophobocity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Preparation of cathode materials for Li-ion cells by acid dissolution

    International Nuclear Information System (INIS)

    Oh, Si Hyoung; Jeong, Woon Tae; Cho, Won Il; Cho, Byung Won; Woo, Kyoungja

    2005-01-01

    New synthesis route called acid dissolution method, preparing the high-performance cathode materials for the lithium-ion cells, was successfully developed. In this method, insoluble starting materials such as metal carbonates or metal hydroxides are dissolved in strong organic acidic solution which contains a chelating agent. And then, the solvent of the solution containing starting materials is eliminated to obtain the xerogel of the initial solution whose chemical form is expressed as Li[MA 3 ], where M is a transition metal atom and A is the anion of the organic acid. The xerogel is then calcined at the high temperature to obtain polycrystalline cathode materials. In this work, the applicability of this method was demonstrated synthesizing a polycrystalline single-phase LiCoO 2 using lithium carbonate, cobalt hydroxide as the insoluble starting materials and the acrylic acid as a chelating agent. The synthesized powders calcined at 800 deg. C showed a good electrochemical performance in the half-cell test

  7. Removal of Heavy Metal Ions with Acid Activated Carbons Derived from Oil Palm and Coconut Shells

    Science.gov (United States)

    Rahman, Mokhlesur M.; Adil, Mohd; Yusof, Alias M.; Kamaruzzaman, Yunus B.; Ansary, Rezaul H.

    2014-01-01

    In this work, batch adsorption experiments were carried out to investigate the suitability of prepared acid activated carbons in removing heavy metal ions such as nickel(II), lead(II) and chromium(VI). Acid activated carbons were obtained from oil palm and coconut shells using phosphoric acid under similar activation process while the differences lie either in impregnation condition or in both pretreatment and impregnation conditions. Prepared activated carbons were modified by dispersing hydrated iron oxide. The adsorption equilibrium data for nickel(II) and lead(II) were obtained from adsorption by the prepared and commercial activated carbons. Langmuir and Freundlich models fit the data well. Prepared activated carbons showed higher adsorption capacity for nickel(II) and lead(II). The removal of chromium(VI) was studied by the prepared acid activated, modified and commercial activated carbons at different pH. The isotherms studies reveal that the prepared activated carbon performs better in low concentration region while the commercial ones in the high concentration region. Thus, a complete adsorption is expected in low concentration by the prepared activated carbon. The kinetics data for Ni(II), Pb(II) and Cr(VI) by the best selected activated carbon fitted very well to the pseudo-second-order kinetic model. PMID:28788640

  8. Removal of Heavy Metal Ions with Acid Activated Carbons Derived from Oil Palm and Coconut Shells

    Directory of Open Access Journals (Sweden)

    Mokhlesur M. Rahman

    2014-05-01

    Full Text Available In this work, batch adsorption experiments were carried out to investigate the suitability of prepared acid activated carbons in removing heavy metal ions such as nickel(II, lead(II and chromium(VI. Acid activated carbons were obtained from oil palm and coconut shells using phosphoric acid under similar activation process while the differences lie either in impregnation condition or in both pretreatment and impregnation conditions. Prepared activated carbons were modified by dispersing hydrated iron oxide. The adsorption equilibrium data for nickel(II and lead(II were obtained from adsorption by the prepared and commercial activated carbons. Langmuir and Freundlich models fit the data well. Prepared activated carbons showed higher adsorption capacity for nickel(II and lead(II. The removal of chromium(VI was studied by the prepared acid activated, modified and commercial activated carbons at different pH. The isotherms studies reveal that the prepared activated carbon performs better in low concentration region while the commercial ones in the high concentration region. Thus, a complete adsorption is expected in low concentration by the prepared activated carbon. The kinetics data for Ni(II, Pb(II and Cr(VI by the best selected activated carbon fitted very well to the pseudo-second-order kinetic model.

  9. Intercomparison of the measurements of oxalic acid in aerosols by gas chromatography and ion chromatography

    Science.gov (United States)

    Kawamura, Kimitaka; Barrie, Leonard A.; Toom-Sauntry, Desiree

    2010-12-01

    Oxalate, the anion of oxalic acid, is one of the most abundant measurable organic species in atmospheric aerosols. Traditionally, this bifunctional species has been measured by gas chromatography (GC) after derivatization to butyl ester and by ion chromatography (IC) without derivatization. However, there are few published comparisons of the two techniques. Here, we report the results of an intercomparison study for the measurement of oxalic acid in Arctic aerosols (oxalic acid by GC ranged from 6.5-59.1 ng m -3 (av. 26.0 ng m -3, median 26.2 ng m -3) whereas those by IC ranged from 6.6-52.1 ng m -3 (av. 26.6 ng m -3, median 25.4 ng m -3). They showed a good correlation ( r = 0.84) with a slope of 0.96. Thus, observations of oxalate obtained by GC employing dibutyl esters are almost equal to those by IC. Because the accuracy of oxalic acid by GC method largely depends on the method used, it is important to strictly examine the recovery in each study.

  10. Laser enhanced reductions of uranium(VI) ion in aqueous phosphoric acid solutions

    International Nuclear Information System (INIS)

    Park, Y.Y.; Harada, M.; Tomiyasu, H.; Ikeda, Y.; Takashima, Y.

    1991-01-01

    Photochemical reactions of U(VI) ions with inorganic anions (I - , Br - , Cl - , NCS - ) and organic compounds (1-hexene, cyclohexene, pyridine) in phosphoric acid were studied for the purpose of finding an efficient method of adjusting the oxidation states of uranium ions in nuclear fuel reprocessing. The formation of U(IV) was observed in the photoreactions with I - , Br - and NCS - , but not with Cl - . The yield of U(VI) increased in the order, Br - - - . This order was the same as the quenching rate constants of the excited U(VI) ions with these anions, and the reverse of their standard redox potentials. The rates of the formation of U(IV) in the presence of Br - were measured spectrophotometrically. It was found that the rate equation was first order in both [U(VI)] and [Br - ]. The results were reasonably interpreted by a series of reaction processes involving U(V) and Br radical. With organic molecules, 1-hexene, cyclohexene, and pyridine, the formation of U(IV) were observed. The yield of U(IV) increased in the order pyridine < 1-hexene < cyclohexene. This order is the reverse of their vertical ionization potentials, suggesting an electron transfer mechanism between these organic molecules and excited U(VI). (author)

  11. Investigation of metal ion extraction and aggregate formation combining acidic and neutral organophosphorous reagents

    Energy Technology Data Exchange (ETDEWEB)

    Braatz, A.D.; Nilsson, M. [Department of Chemical Engineering and Materials Science, 916 Engineering Tower, University of California-Irvine, Irvine, CA 92697-2575 (United States); Ellis, R.; Antonio, M. [Chemical Science and Engineering Division, Argonne National Laboratory, Building 200 9700 South Cass Ave, Argonne, IL 60439-4831 (United States)

    2013-07-01

    In the present study, we investigate how varying mixtures of tri-n-butyl phosphate (TBP) and dibutyl phosphate (HDBP) results in enhanced extraction of lanthanum(III), La{sup 3+}, and dysprosium(III), Dy{sup 3+}. Water and metal ion extraction were carefully monitored as a function of TBP:HDBP mole ratio.In addition to these techniques, EXAFS was used to determine the coordination environment of the metal ion in this system. To produce the necessary signal, a concentration of 1.25*10{sup -3} M La{sup 3+} and Dy{sup 3+} was used. Although previous studies of synergistic extraction of metal cations using combinations of neutral and acidic reagents explain the enhanced extraction by increased dehydration of the metal ion and the formation of mixed extractant complexes, our evidence for the increased water extraction coupled with the aggregate formation suggests a reverse micellar aspect to synergism in the system containing TBP and HDBP. It is quite possible that both of these phenomena contribute to our system behavior. The EXAFS data shows that, based on coordination numbers alone, several possible structures may exist. From this study, we cannot provide a definitive answer as to the nature of extraction in this system or the exact complex formed during extraction.

  12. Regulation of ion homeostasis by aminolevulinic acid in salt-stressed wheat seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Türk, Hülya, E-mail: hulyaa.turk@hotmail.com [Biology Department, Science Faculty, Ataturk University, Erzurum (Turkey); East Anatolian High Technology Research and Application Center, Ataturk University, Erzurum (Turkey); Genişel, Mucip, E-mail: m.genisel@hotmail.com [Department of Crop and Animal Production, Vocational High School, Agri (Turkey); Erdal, Serkan, E-mail: serkanerdal25@hotmail.com [Biology Department, Science Faculty, Ataturk University, Erzurum (Turkey)

    2016-04-18

    Salinity is regarded as a worldwide agricultural threat, as it seriously limits plant development and productivity. Salt stress reduces water uptake in plants by disrupting the osmotic balance of soil solution. In addition, it creates a damaged metabolic process by causing ion imbalance in cells. In this study, we aim to examine the negative effects of 5-aminolevulinic acid (ALA) (20 mg/l) on the ion balance in wheat seedling leaves exposed to salt stress (150 mM). Sodium is known to be highly toxic for plant cells at high concentrations, and is significantly increased by salt stress. However, it can be reduced by combined application of ALA and salt, compared to salt application alone. On the other hand, while the K{sup +}/Na{sup +} ratio was reduced by salt stress, ALA application changed this ratio in favor of K{sup +}. Manganese, iron, and copper were also able to reduce stress. However, ALA pre-treatment resulted in mineral level increments. Conversely, the stress-induced rise in magnesium, potassium, calcium, phosphorus, zinc, and molybdenum were further improved by ALA application. These data clearly show that ALA has an important regulatory effect of ion balance in wheat leaves.

  13. D-penicillamine-templated copper nanoparticles via ascorbic acid reduction as a mercury ion sensor.

    Science.gov (United States)

    Lin, Shu Min; Geng, Shuo; Li, Na; Li, Nian Bing; Luo, Hong Qun

    2016-05-01

    Mercury ion is one of the most hazardous metal pollutants that can cause deleterious effects on human health and the environment even at low concentrations. It is necessary to develop new mercury detection methods with high sensitivity, specificity and rapidity. In this study, a novel and green strategy for synthesizing D-penicillamine-capped copper nanoparticles (DPA-CuNPs) was successfully established by a chemical reduction method, in which D-penicillamine and ascorbic acid were used as stabilizing agent and reducing agent, respectively. The as-prepared DPA-CuNPs showed strong red fluorescence and had a large Stoke's shift (270nm). Scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, fluorescence spectroscopy, and ultraviolet-visible spectrophotometry were utilized to elucidate the possible fluorescence mechanism, which could be aggregation-induced emission effect. Based on the phenomenon that trace mercury ion can disperse the aggregated DPA-CuNPs, resulting in great fluorescence quench of the system, a sensitive and selective assay for mercury ion in aqueous solution with the DPA-CuNPs was developed. Under optimum conditions, this assay can be applied to the quantification of Hg(2+) in the 1.0-30μM concentration range and the detection limit (3σ/slope) is 32nM. The method was successfully applied to determine Hg(2+) in real water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Electronic spectra of plutonium ions in nitric acid and in lithium nitrate solutions

    International Nuclear Information System (INIS)

    Mekhail, F.M.

    1987-01-01

    The absorption spectra of plutonium ions in nitric acid have been described. There is a characteristic change in the absorption spectra of Pu v in lithium nitrate solutions. In 2 M-lithium nitrate a new peak at 969 nm and high absorption at 1200 nm are noticed. A decrease in the absorption by about 20% and the appearance of a new shoulder at 1120 nm in 6 M-lithium nitrate are found. There is no change in the spectrum in 4 M-lithium nitrate. The absorption spectra of plutonium ions in the spectral range 200 - 400 nm are interesting. All plutonium ions have an intense band in the region 250 - 260 nm as well as a less intense and rather diffuse band at 320 - 330 nm in lithium nitrate solutions the sharp band at 250 - 260 nm has disappeared. This suggests that this band is very sensitive to the environmental field. The band is probably produced by 5 F q → 5 f q-1 6 d transition as well as electron transfer. It is believed that the spectrum of Pu V at pH 6.5 represents the hydrolysis product Pu O 2 (O H). 9 fig., 4 tab

  15. Kinetics and thermodynamics of aluminium dissolution in 1.0M sulphuric acid containing chloride ions

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Gaber, A.M. [Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria 21321 (Egypt)]. E-mail: ashrafmoustafa@yahoo.com; Abd-El-Nabey, B.A. [Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria 21321 (Egypt); Sidahmed, I.M. [Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria 21321 (Egypt); El-Zayady, A.M. [Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria 21321 (Egypt); Saadawy, M. [Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria 21321 (Egypt)

    2006-08-01

    The dissolution of aluminium in 1M sulphuric acid solutions containing different chloride ion concentrations (0.01-0.06M) were studied at 25, 30, 35 and 40deg. C using electrochemical impedance spectroscopy (EIS) technique and polarization curves measurements. The kinetic rate equation, under the experimental condition described, was derived and found to verify the following relationship:V=k{sub obs}K{sub 2}C{sub Cl{sup -}}{sup n}1+K{sub 2}C{sub Cl{sup -}}{sup n}where V is the corrosion rate, k{sub obs} and K{sub 2} are the dissolution rate constant of aluminium oxide-chloride complex and the equilibrium constant of chloride ions adsorbed at aluminium oxide surface, respectively. The kinetic and thermodynamic energy parameters were calculated and their values indicate that chloride ions are chemisorbed onto the aluminium oxide surface and the formation of oxide-chloride complex is the rate-determining step.

  16. Molecular models of alginic acid: Interactions with calcium ions and calcite surfaces

    Science.gov (United States)

    Perry, Thomas D.; Cygan, Randall T.; Mitchell, Ralph

    2006-07-01

    Cation binding by polysaccharides is observed in many environments and is important for predictive environmental modeling, and numerous industrial and food technology applications. The complexities of these cation-organic interactions are well suited for predictive molecular modeling and the analysis of conformation and configuration of polysaccharides and their influence on cation binding. In this study, alginic acid was chosen as a model polymer system and representative disaccharide and polysaccharide subunits were developed. Molecular dynamics simulation of the torsion angles of the ether linkage between various monomeric subunits identified local and global energy minima for selected disaccharides. The simulations indicate stable disaccharide configurations and a common global energy minimum for all disaccharide models at Φ = 274 ± 7°, Ψ = 227 ± 5°, where Φ and Ψ are the torsion angles about the ether linkage. The ability of disaccharide subunits to bind calcium ions and to associate with the (101¯4) surface of calcite was also investigated. Molecular models of disaccharide interactions with calcite provide binding energy differences for conformations that are related to the proximity and residence densities of the electron-donating moieties with calcium ions on the calcite surface, which are controlled, in part, by the torsion of the ether linkage between monosaccharide units. Dynamically optimized configurations for polymer alginate models with calcium ions were also derived.

  17. Identification of metal ion binding sites based on amino acid sequences.

    Science.gov (United States)

    Cao, Xiaoyong; Hu, Xiuzhen; Zhang, Xiaojin; Gao, Sujuan; Ding, Changjiang; Feng, Yonge; Bao, Weihua

    2017-01-01

    The identification of metal ion binding sites is important for protein function annotation and the design of new drug molecules. This study presents an effective method of analyzing and identifying the binding residues of metal ions based solely on sequence information. Ten metal ions were extracted from the BioLip database: Zn2+, Cu2+, Fe2+, Fe3+, Ca2+, Mg2+, Mn2+, Na+, K+ and Co2+. The analysis showed that Zn2+, Cu2+, Fe2+, Fe3+, and Co2+ were sensitive to the conservation of amino acids at binding sites, and promising results can be achieved using the Position Weight Scoring Matrix algorithm, with an accuracy of over 79.9% and a Matthews correlation coefficient of over 0.6. The binding sites of other metals can also be accurately identified using the Support Vector Machine algorithm with multifeature parameters as input. In addition, we found that Ca2+ was insensitive to hydrophobicity and hydrophilicity information and Mn2+ was insensitive to polarization charge information. An online server was constructed based on the framework of the proposed method and is freely available at http://60.31.198.140:8081/metal/HomePage/HomePage.html.

  18. Molecularly imprinted polymer-matrix nanocomposite for enantioselective electrochemical sensing of D- and L-aspartic acid

    International Nuclear Information System (INIS)

    Prasad, Bhim Bali; Srivastava, Amrita; Tiwari, Mahavir Prasad

    2013-01-01

    A new molecularly imprinted polymer-matrix (titanium dioxide nanoparticle/multiwalled carbon nanotubes) nanocomposite was developed for the modification of pencil graphite electrode as an enantioselective sensing probe for aspartic acid isomers, prevalent at ultra trace level in aqueous and real samples. The nanocomposite having many shape complementary cavities was synthesized adopting surface initiated-activators regenerated by electron transfer for atom transfer radical polymerization. The proposed sensor has high stability, nanocomposite uniformity, good reproducibility, and enhanced electrocatalytic activity to respond oxidative peak current of L-aspartic acid quantitatively by differential pulse anodic stripping voltammetry, without any cross-reactivity in real samples. Under the optimized operating conditions, the L-aspartic acid imprinted modified electrode showed a wide linear response for L-aspartic acid within the concentration range 9.98–532.72 ng mL −1 , with the minimum detection limit of 1.73–1.79 ng mL −1 (S/N = 3) in aqueous and real samples. Almost similar stringent limit (1.79 ng mL −1 ) was obtained with cerebrospinal fluid which is typical for the primitive diagnosis of neurological disorders, caused by an acute depletion of L-aspartic acid biomarker, in clinical settings. Highlights: • We have adopted surface initiated-activators regenerated by electron transfer for atom transfer radical polymerization. • This approach takes advantage of the nanostructured ultrathin imprinted film. • Successful enantioselective sensing and ultratrace analysis of D- and L-aspartic acid. • Stringent detection limit without any non-specific false-positive contribution

  19. Molecularly imprinted polymer-matrix nanocomposite for enantioselective electrochemical sensing of D- and L-aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Bhim Bali, E-mail: prof.bbpd@yahoo.com; Srivastava, Amrita; Tiwari, Mahavir Prasad

    2013-10-15

    A new molecularly imprinted polymer-matrix (titanium dioxide nanoparticle/multiwalled carbon nanotubes) nanocomposite was developed for the modification of pencil graphite electrode as an enantioselective sensing probe for aspartic acid isomers, prevalent at ultra trace level in aqueous and real samples. The nanocomposite having many shape complementary cavities was synthesized adopting surface initiated-activators regenerated by electron transfer for atom transfer radical polymerization. The proposed sensor has high stability, nanocomposite uniformity, good reproducibility, and enhanced electrocatalytic activity to respond oxidative peak current of L-aspartic acid quantitatively by differential pulse anodic stripping voltammetry, without any cross-reactivity in real samples. Under the optimized operating conditions, the L-aspartic acid imprinted modified electrode showed a wide linear response for L-aspartic acid within the concentration range 9.98–532.72 ng mL{sup −1}, with the minimum detection limit of 1.73–1.79 ng mL{sup −1} (S/N = 3) in aqueous and real samples. Almost similar stringent limit (1.79 ng mL{sup −1}) was obtained with cerebrospinal fluid which is typical for the primitive diagnosis of neurological disorders, caused by an acute depletion of L-aspartic acid biomarker, in clinical settings. Highlights: • We have adopted surface initiated-activators regenerated by electron transfer for atom transfer radical polymerization. • This approach takes advantage of the nanostructured ultrathin imprinted film. • Successful enantioselective sensing and ultratrace analysis of D- and L-aspartic acid. • Stringent detection limit without any non-specific false-positive contribution.

  20. Synergistic inhibition between o-phenanthroline and chloride ion for steel corrosion in sulphuric acid

    International Nuclear Information System (INIS)

    Li Xueming; Tang Libin; Li Lin; Mu Guannan; Liu Guangheng

    2006-01-01

    The corrosion inhibition of cold rolled steel in 0.5 M sulphuric acid in the presence of o-phenanthroline and sodium chloride (NaCl) has been investigated by using weight loss and electrochemical techniques. The experimental data suggest that the inhibition efficiency increases with increasing NaCl concentration in the presence of 0.0002 M o-phenanthroline, but decreases with increasing temperature. A synergistic effect is observed when o-phenanthroline and chloride ions are used together to prevent cold rolled steel corrosion in 0.5 M sulphuric acid. The polarization curves showed that the complex of o-phenanthroline and NaCl acts as a mixed type inhibitor. The experimental results suggested that the presence of chloride ions in the solution stabilized the adsorption of o-phenanthroline molecules on the metal surface and improved the inhibition efficiency of o-phenanthroline. The adsorption of the complex accords with the Langmuir adsorption isotherm. Some thermodynamic parameters such as adsorption heat, adsorption entropy and adsorption free energy have been calculated by employing thermodynamic equations. Kinetic parameters such as apparent activation energy and pre-exponential factor have been calculated and discussed

  1. Target-induced formation of gold amalgamation on DNA-based sensing platform for electrochemical monitoring of mercury ion coupling with cycling signal amplification strategy

    International Nuclear Information System (INIS)

    Chen, Jinfeng; Tang, Juan; Zhou, Jun; Zhang, Lan; Chen, Guonan; Tang, Dianping

    2014-01-01

    Graphical abstract: -- Highlights: •We report a new electrochemical sensing protocol for the detection of mercury ion. •Gold amalgamation on DNA-based sensing platform was used as nanocatalyst. •The signal was amplified by cycling signal amplification strategy. -- Abstract: Heavy metal ion pollution poses severe risks in human health and environmental pollutant, because of the likelihood of bioaccumulation and toxicity. Driven by the requirement to monitor trace-level mercury ion (Hg 2+ ), herein we construct a new DNA-based sensor for sensitive electrochemical monitoring of Hg 2+ by coupling target-induced formation of gold amalgamation on DNA-based sensing platform with gold amalgamation-catalyzed cycling signal amplification strategy. The sensor was simply prepared by covalent conjugation of aminated poly-T (25) oligonucleotide onto the glassy carbon electrode by typical carbodiimide coupling. Upon introduction of target analyte, Hg 2+ ion was intercalated into the DNA polyion complex membrane based on T–Hg 2+ –T coordination chemistry. The chelated Hg 2+ ion could induce the formation of gold amalgamation, which could catalyze the p-nitrophenol with the aid of NaBH 4 and Ru(NH 3 ) 6 3+ for cycling signal amplification. Experimental results indicated that the electronic signal of our system increased with the increasing Hg 2+ level in the sample, and has a detection limit of 0.02 nM with a dynamic range of up to 1000 nM Hg 2+ . The strategy afforded exquisite selectivity for Hg 2+ against other environmentally related metal ions. In addition, the methodology was evaluated for the analysis of Hg 2+ in spiked tap-water samples, and the recovery was 87.9–113.8%

  2. Target-induced formation of gold amalgamation on DNA-based sensing platform for electrochemical monitoring of mercury ion coupling with cycling signal amplification strategy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jinfeng; Tang, Juan; Zhou, Jun; Zhang, Lan; Chen, Guonan; Tang, Dianping, E-mail: dianping.tang@fzu.edu.cn

    2014-01-31

    Graphical abstract: -- Highlights: •We report a new electrochemical sensing protocol for the detection of mercury ion. •Gold amalgamation on DNA-based sensing platform was used as nanocatalyst. •The signal was amplified by cycling signal amplification strategy. -- Abstract: Heavy metal ion pollution poses severe risks in human health and environmental pollutant, because of the likelihood of bioaccumulation and toxicity. Driven by the requirement to monitor trace-level mercury ion (Hg{sup 2+}), herein we construct a new DNA-based sensor for sensitive electrochemical monitoring of Hg{sup 2+} by coupling target-induced formation of gold amalgamation on DNA-based sensing platform with gold amalgamation-catalyzed cycling signal amplification strategy. The sensor was simply prepared by covalent conjugation of aminated poly-T{sub (25)} oligonucleotide onto the glassy carbon electrode by typical carbodiimide coupling. Upon introduction of target analyte, Hg{sup 2+} ion was intercalated into the DNA polyion complex membrane based on T–Hg{sup 2+}–T coordination chemistry. The chelated Hg{sup 2+} ion could induce the formation of gold amalgamation, which could catalyze the p-nitrophenol with the aid of NaBH{sub 4} and Ru(NH{sub 3}){sub 6}{sup 3+} for cycling signal amplification. Experimental results indicated that the electronic signal of our system increased with the increasing Hg{sup 2+} level in the sample, and has a detection limit of 0.02 nM with a dynamic range of up to 1000 nM Hg{sup 2+}. The strategy afforded exquisite selectivity for Hg{sup 2+} against other environmentally related metal ions. In addition, the methodology was evaluated for the analysis of Hg{sup 2+} in spiked tap-water samples, and the recovery was 87.9–113.8%.

  3. Nectar sugars and amino acids in day- and night-flowering Nicotiana species are more strongly shaped by pollinators' preferences than organic acids and inorganic ions.

    Science.gov (United States)

    Tiedge, Kira; Lohaus, Gertrud

    2017-01-01

    Floral nectar contains mainly sugars but also amino acids, organic acids, inorganic ions and secondary compounds to attract pollinators. The genus Nicotiana exhibits great diversity among species in floral morphology, flowering time, nectar compositions, and predominant pollinators. We studied nectar samples of 20 Nicotiana species, composed equally of day- and night-flowering plants and attracting different groups of pollinators (e.g. hummingbirds, moths or bats) to investigate whether sugars, amino acids, organic acids and inorganic ions are influenced by pollinator preferences. Glucose, fructose and sucrose were the only sugars found in the nectar of all examined species. Sugar concentration of the nectar of day-flowering species was 20% higher and amino acid concentration was 2-3-fold higher compared to the nectar of night-flowering species. The sucrose-to-hexose ratio was significantly higher in night-flowering species and the relative share of sucrose based on the total sugar correlated with the flower tube length in the nocturnal species. Flowers of different tobacco species contained varying volumes of nectar which led to about 150-fold higher amounts of total sugar per flower in bat- or sunbird-pollinated species than in bee-pollinated or autogamous species. This difference was even higher for total amino acids per flower (up to 1000-fold). As a consequence, some Nicotiana species invest large amounts of organic nitrogen for certain pollinators. Higher concentrations of inorganic ions, predominantly anions, were found in nectar of night-flowering species. Therefore, higher anion concentrations were also associated with pollinator types active at night. Malate, the main organic acid, was present in all nectar samples but the concentration was not correlated with pollinator type. In conclusion, statistical analyses revealed that pollinator types have a stronger effect on nectar composition than phylogenetic relations. In this context, nectar sugars and amino

  4. Nectar sugars and amino acids in day- and night-flowering Nicotiana species are more strongly shaped by pollinators’ preferences than organic acids and inorganic ions

    Science.gov (United States)

    Tiedge, Kira; Lohaus, Gertrud

    2017-01-01

    Floral nectar contains mainly sugars but also amino acids, organic acids, inorganic ions and secondary compounds to attract pollinators. The genus Nicotiana exhibits great diversity among species in floral morphology, flowering time, nectar compositions, and predominant pollinators. We studied nectar samples of 20 Nicotiana species, composed equally of day- and night-flowering plants and attracting different groups of pollinators (e.g. hummingbirds, moths or bats) to investigate whether sugars, amino acids, organic acids and inorganic ions are influenced by pollinator preferences. Glucose, fructose and sucrose were the only sugars found in the nectar of all examined species. Sugar concentration of the nectar of day-flowering species was 20% higher and amino acid concentration was 2-3-fold higher compared to the nectar of night-flowering species. The sucrose-to-hexose ratio was significantly higher in night-flowering species and the relative share of sucrose based on the total sugar correlated with the flower tube length in the nocturnal species. Flowers of different tobacco species contained varying volumes of nectar which led to about 150-fold higher amounts of total sugar per flower in bat- or sunbird-pollinated species than in bee-pollinated or autogamous species. This difference was even higher for total amino acids per flower (up to 1000-fold). As a consequence, some Nicotiana species invest large amounts of organic nitrogen for certain pollinators. Higher concentrations of inorganic ions, predominantly anions, were found in nectar of night-flowering species. Therefore, higher anion concentrations were also associated with pollinator types active at night. Malate, the main organic acid, was present in all nectar samples but the concentration was not correlated with pollinator type. In conclusion, statistical analyses revealed that pollinator types have a stronger effect on nectar composition than phylogenetic relations. In this context, nectar sugars and amino

  5. Nectar sugars and amino acids in day- and night-flowering Nicotiana species are more strongly shaped by pollinators' preferences than organic acids and inorganic ions.

    Directory of Open Access Journals (Sweden)

    Kira Tiedge

    Full Text Available Floral nectar contains mainly sugars but also amino acids, organic acids, inorganic ions and secondary compounds to attract pollinators. The genus Nicotiana exhibits great diversity among species in floral morphology, flowering time, nectar compositions, and predominant pollinators. We studied nectar samples of 20 Nicotiana species, composed equally of day- and night-flowering plants and attracting different groups of pollinators (e.g. hummingbirds, moths or bats to investigate whether sugars, amino acids, organic acids and inorganic ions are influenced by pollinator preferences. Glucose, fructose and sucrose were the only sugars found in the nectar of all examined species. Sugar concentration of the nectar of day-flowering species was 20% higher and amino acid concentration was 2-3-fold higher compared to the nectar of night-flowering species. The sucrose-to-hexose ratio was significantly higher in night-flowering species and the relative share of sucrose based on the total sugar correlated with the flower tube length in the nocturnal species. Flowers of different tobacco species contained varying volumes of nectar which led to about 150-fold higher amounts of total sugar per flower in bat- or sunbird-pollinated species than in bee-pollinated or autogamous species. This difference was even higher for total amino acids per flower (up to 1000-fold. As a consequence, some Nicotiana species invest large amounts of organic nitrogen for certain pollinators. Higher concentrations of inorganic ions, predominantly anions, were found in nectar of night-flowering species. Therefore, higher anion concentrations were also associated with pollinator types active at night. Malate, the main organic acid, was present in all nectar samples but the concentration was not correlated with pollinator type. In conclusion, statistical analyses revealed that pollinator types have a stronger effect on nectar composition than phylogenetic relations. In this context

  6. Spontaneous arylation of activated carbon from aminobenzene organic acids as source of diazonium ions in mild conditions

    International Nuclear Information System (INIS)

    Lebègue, Estelle; Brousse, Thierry; Gaubicher, Joël; Cougnon, Charles

    2013-01-01

    Activated carbon products modified with benzoic, benzenesulfonic and benzylphosphonic acid groups were prepared by spontaneous reduction of aryldiazonium ions in situ generated in water from the corresponding aminobenzene organic acids without addition of an external acid. Electrochemistry and NMR studies show that the advancement of the diazotization reaction depends both on the acidity and the electronic effect of the organic acid substituent, giving a mixture of diazonium, amine and triazene functionalities. Carbon products prepared by reaction of activated carbon Norit with 4-aminobenzenecarboxylic acid, 4-aminobenzenesulfonic acid and (4-aminobenzyl)phosphonic acid were analyzed by chemical elemental analysis and X-ray photoelectron spectroscopy experiments. Results show that this strategy is well suited for the chemical functionalization, giving a maximized grafting yield due to a chemical cooperation of amine and diazonium functionalities

  7. Molecularly imprinted polyaniline-ferrocene-sulfonic acid-Carbon dots modified pencil graphite electrodes for chiral selective sensing of D-Ascorbic acid and L-Ascorbic acid: A clinical biomarker for preeclampsia

    International Nuclear Information System (INIS)

    Pandey, Indu; Jha, Shashank Shekhar

    2015-01-01

    Highlights: • Pencil graphite electrode was non-covalently functionalized by C-dots. • Electrochemically synthesized ferrocene-sulfonic acid doped PANI film was used as chiral recognition element. • Electrochemical chiral sensing of L-ascorbic acid and D-ascorbic acid was carried out. • L-ascorbic acid determination was done in aqueous, biological and pharmaceutical samples at nM level. - Abstract: A simple and novel method is proposed for chiral separation of L-ascorbic acid and D-ascorbic acid in human cerebrospinal fluids and blood plasma samples. Electro-polymerized molecularly imprinted poly-aniline ferrocenesulfonic acid-C-dots modified pencil graphite electrodes was successfully applied for separation and quantification of D-/L-ascorbic acid in aqueous and some biological samples. Parameters, important to control the performance of the electrochemical sensor were investigated and optimized, including the effects of pH, monomer- template ratios, electropolymerization cycles and scan rates. The molecularly imprinted film exhibited a high chiral selectivity and sensitivity towards D-ascorbic acid and L-ascorbic acid respectively. The surface morphologies and electrochemical properties of the proposed sensor were characterized by scanning electron microscopy, cyclic voltammetry, difference pulse voltammetry, chrono-amperometry and electrochemical impedance spectroscopy. L-ascorbic acid selective sensor shows excellent selectivity towards the L-ascorbic acid in comparison to D- ascorbic acid vice versa for D- ascorbic acid selective sensor. Under optimal conditions the linear range of the calibration curve for L- ascorbic acid and D- ascorbic acid was 6.0–165.0 nM and 6.0–155.0 nM, with the detection limit of 0.001 nM and 0.002 nM. Chiral detection of L-ascorbic acid was successfully carried out in pharmaceuticals and human plasma samples (pregnant women and non pregnant women) via proposed sensor with good selectivity and sensitivity.

  8. "Clickable" LNA/DNA probes for fluorescence sensing of nucleic acids and autoimmune antibodies

    DEFF Research Database (Denmark)

    Jørgensen, Anna S; Gupta, Pankaj; Wengel, Jesper

    2013-01-01

    Herein we describe fluorescent oligonucleotides prepared by click chemistry between novel alkyne-modified locked nucleic acid (LNA) strands and a series of fluorescent azides for homogeneous (all-in-solution) detection of nucleic acids and autoimmune antibodies.......Herein we describe fluorescent oligonucleotides prepared by click chemistry between novel alkyne-modified locked nucleic acid (LNA) strands and a series of fluorescent azides for homogeneous (all-in-solution) detection of nucleic acids and autoimmune antibodies....

  9. Electrochemical studies on the reduction of uranyl ions in nitric acid-hydrazine media at platinum electrode

    International Nuclear Information System (INIS)

    Mishra, Satyabrata; Sini, K.; Mallika, C.; Kamachi Mudali, U.; Jagadeeswara Rao, Ch.

    2015-01-01

    Production of uranous nitrate with good conversion efficiency is one of the major steps in the aqueous reprocessing of spent fuels of nuclear reactors, as U(IV) is used for the separation of Pu from U by the selective reduction of Pu(IV) into practically non-extractable Pu(III) in aqueous streams. Electro-reduction of uranyl ions has the advantage of not introducing corrosive chemicals into the process stream. High current efficiency with maximum conversion of U(VI) to U(IV) can be achieved in continuous as well as batch mode electro-reduction, if the process is voltage-controlled rather than current controlled. As potentiostatic studies reveal the mechanism of reduction of uranyl ions in potential controlled electrolysis, the reduction behavior of uranyl ions (UO 2 2+ ) in nitric acid and nitric acid-hydrazine media were investigated by Cyclic Voltammetric (CV) and Chronopotentiometric (CP) techniques using platinum working electrode at 298 K. Heterogeneous electron transfer rate constant (ks) for uranyl reduction was estimated at a very low concentration of nitric acid (0.05 M) using Klinger and Kochi equation. Values of the diffusion coefficients were determined as a function of acidity with and without hydrazine. Reduction of uranyl ions was found to be under kinetic as well as diffusion control when the concentration of nitric acid was 0.05 M and in the absence of hydrazine. However, as the acidity of the supporting electrolyte increased, the reduction was purely under kinetic control. (author)

  10. Determination of feedstuff amino acids composition by ion-exchange chromatography

    Directory of Open Access Journals (Sweden)

    A. A. Volnin

    2018-01-01

    Full Text Available Determination of animal feeds amino acids composition is the very important part of agricultural sciences and livestock management. This is necessary for normalization and balanced of farm animal’s diets parameters. Advances in husbandry techniques are making in response to the needs for rearing high genetic merit livestock. The nutrition of livestock has a critical role in these developments and is an element which needs to be continually updated as new scientific information becomes available. This article is devoted to the use of ion-exchange chromatography with post-colum derivatization by ninhydrin in the study of the amino acid composition and evaluation of the biological value of livestock feedstuff components. The amino acid composition (except tryptophan of the livestock feed-stuff component is presented for threonine – 3.26 g/100g of protein, leucine – 6.43, isoleucine – 3.24, valine – 4.77, methionine – 2.18, lysine – 2.90, phenylalanine – 3.16, histidine – 2.03, tyrosine – 2.33, sum of asparagine and aspartate – 6.76, serine – 3.97, sum of glutamine and glutamic acid – 12.04, glycine – 6.00, alanine – 6.71, arginine – 6.93, proline – 3.08, sum of cystine and cysteine – 1.38. Biological value of feedstuff component compared with the "ideal" protein (FAO WHO is estimated, limiting amino acids were found. The amino acid score was calculated: for threonine – 81.5%, leucine – 91.9%, isoleucine – 81%, valine – 95.4%, lysine – 52.7%, phenylalanine and tyrosine sum – 91.5%, methionine and cysteine sum – 101.7%. Feedstuff component had a low level of essential amino acids in compare with "ideal" protein (FAO WHO. Feedstuff component can be used for livestock nutrition as a component of essential amino-acid balanced diet.

  11. Ethylenediamine-functionalized graphene oxide incorporated acid-base ion exchange membranes for vanadium redox flow battery

    International Nuclear Information System (INIS)

    Liu, Shuai; Li, Dan; Wang, Lihua; Yang, Haijun; Han, Xutong; Liu, Biqian

    2017-01-01

    Highlights: • Ethylenediamine functionalized graphene oxide. • Layered structure of functionalized graphene oxide block vanadium ions crossover. • Protonated N-containing groups suppress vanadium ions permeation. • Ion transport channels are narrowed by electrostatic interactions. • Vanadium crossover decreased due to enhanced Donnan effect and special structure. - Abstract: As a promising large-scale energy storage battery, vanadium redox flow battery (VRFB) is urgently needed to develop cost-effective membranes with excellent performance. Novel acid-base ion exchange membranes (IEMs) are fabricated based on sulfonated poly(ether ether ketone) (SPEEK) matrix and modified graphene oxide (GO) by solution blending. N-based functionalized graphene oxide (GO-NH 2 ) is fabricated by grafting ethylenediamine onto the edge of GO via a facile method. On one hand, the impermeable layered structures effectively block ion transport pathway to restrain vanadium ions crossover. On the other hand, acid-base pairs form between −SO 3 − groups and N-based groups on the edge of GO nanosheets, which not only suppress vanadium ions contamination but also provide a narrow pathway for proton migration. The structure is beneficial for achieving an intrinsic balance between conductivity and permeability. By altering amounts of GO-NH 2 , a sequence of acid-base IEMs are characterized in detail. The single cells assembled with acid-base IEMs show self-discharge time for 160 h, capacity retention 92% after 100 cycle, coulombic efficiency 97.2% and energy efficiency 89.5%. All data indicate that acid-base IEMs have promising prospects for VRFB applications.

  12. Multistage leaching of metals from spent lithium ion battery waste using electrochemically generated acidic lixiviant.

    Science.gov (United States)

    Boxall, N J; Adamek, N; Cheng, K Y; Haque, N; Bruckard, W; Kaksonen, A H

    2018-04-01

    Lithium ion battery (LIB) waste contains significant valuable resources that could be recovered and reused to manufacture new products. This study aimed to develop an alternative process for extracting metals from LIB waste using acidic solutions generated by electrolysis for leaching. Results showed that solutions generated by electrolysis of 0.5 M NaCl at 8 V with graphite or mixed metal oxide (MMO) electrodes were weakly acidic and leach yields obtained under single stage (batch) leaching were poor (leaching with the graphite electrolyte solution improved leach yields overall, but the electrodes corroded over time. Though yields obtained with both electrolyte leach solutions were low when compared to the 4 M HCl control, there still remains potential to optimise the conditions for the generation of the acidic anolyte solution and the solubilisation of valuable metals from the LIB waste. A preliminary value proposition indicated that the process has the potential to be economically feasible if leach yields can be improved, especially based on the value of recoverable cobalt and lithium. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. The oxidation of uranium(IV) ions by nitrous acid in 30% tri-butyl phosphate

    International Nuclear Information System (INIS)

    Koltunov, V.S.; Marchenko, V.I.; Savilova, O.A.; Dvoeglazov, K.N.; Taylor, R.J.

    2004-01-01

    The kinetics of the oxidation of U(IV) ions by nitrous acid in a 30% TBP solution have been determined. The rate equation was found to be: - d[U(IV)] / dt = k 2a [U(IV)][HNO 2 ][HNO 3 ][H 2 O] / [HNO 3 ] 2 + β 3 [HNO 3 ][H 2 O] + β 4 [H 2 O] 2 , where, k 2a = 0.405 ± 0.055 M -1 min -1 at 55 C (β 3 ∼ 0.08; β 4 ∼ 0.007) and the activation energy was E = 112 ± 17 kJ mol -1 . The reaction mechanism appeared to involve interaction with the 1 st hydrolysis product of U(IV)-UOH 3+ . The data is compared with a previous study of the nitric acid oxidation of U(IV) in 30% TBP. This reaction is autocatalytic due to the formation of nitrous acid during the reaction. The kinetics of the decomposition of HNO 2 in 30% TBP (in the absence of U(IV)) have also been reported. (orig.)

  14. Equilibrium studies of ternary systems containing some selected transition metal ions, triazoles and aromatic carboxylic acids

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, Mohamed Magdy; Radalla, Abd-Elatty; Qasem, Fatma; Khaled, Rehab [Beni-Suef University, Beni-Suef (Egypt)

    2014-01-15

    Solution equilibria of the binary and ternary complex systems of the divalent transition metal ions Cu{sup 2+}, Ni{sup 2+}, Zn{sup 2+}, and Co{sup 2+} with 1,2,4-triazole (TRZ), 3-mercapto-1,2,4-triazole (TRZSH), and 3-amino-1,2,4-triazole (TRZAM) and aromatic carboxylic acids (phthalic, anthranilic, salicylic, and 5-sulfosalicylic acid) have been studied pH-metrically at (25.0±0.1) .deg. C, and a constant ionic strength I=1x10{sup -1} mol L{sup -1} NaNO{sub 3} in an aqueous medium. The potentiometric titration curves show that binary and ternary complexes of these ligands are formed in solution. The stability constants of the different binary and ternary complexes formed were calculated on the basis of computer analysis of the titration data. The relative stability of the different ternary complex species is expressed in terms of Δ log K values, log X and R. S.% parameters. The effect of temperature of the medium on both the proton-ligand equilibria for TRZAM and phthalic acid and their metal-ligand equilibria with Cu{sup 2+}, Ni{sup 2+}, and Co{sup 2+} has been studied along with the corresponding thermodynamic parameters. The complexation behavior of ternary complexes is ascertained using conductivity measurements. In addition, the formation of ternary complexes in solution has been confirmed by using UV-visible spectrophotometry.

  15. Removing and recovering of uranium from the acid mine waters by using ion exchange resin

    International Nuclear Information System (INIS)

    Nascimento, Marcos Roberto Lopes do

    1998-01-01

    Ion exchange using resins is one of the few processes capable of reducing ionic contaminants in effluents to very low levels. In this study the process was used to remove and recovery uranium from acid mine waters at Pocos de Caldas-MG Uranium Mining and Milling Plant. The local mineralogical features, allied to the biogeochemical phenomena, owing to presence of pyrite in the rock piles, moreover another factors, resulting acid drainage with several pollutants, including uranium ranging from 6 to 14 mg/l, as sulfate complex, that can be removed by anionic exchanger. The iron interference is eliminated by lime pretreatment of water, increasing pH from 2.6 to 3.3-3.8 to precipitate this cation, without changing the uranium amount. Eight anionic resins were tested, based on the uranium loading, in sorption studies. Retention time, and pH influence was verified for the exchanger chose. With breakthrough of 1 mg U/L and 10 mg U/l in the feed solution, the uranium decontamination level was 94%. Typical values of loading resin were 20-30 g U/l and 70-90 g SO 4 /l. Uranium elution was done with Na Cl solution. Retention time, saline, and acid concentration were the parameters studied. The concentrate, obtained from the eluate by ammonia precipitation, presented uranium (86,8% as U 3 O 8 ) and impurities within commercial specifications. (author)

  16. Role played by acid-sensitive ion channels in evoking the exercise pressor reflex.

    Science.gov (United States)

    Hayes, Shawn G; McCord, Jennifer L; Rainier, Jon; Liu, Zhuqing; Kaufman, Marc P

    2008-10-01

    The exercise pressor reflex arises from contracting skeletal muscle and is believed to play a role in evoking the cardiovascular responses to static exercise, effects that include increases in arterial pressure and heart rate. This reflex is believed to be evoked by the metabolic and mechanical stimulation of thin fiber muscle afferents. Lactic acid is known to be an important metabolic stimulus evoking the reflex. Until recently, the only antagonist for acid-sensitive ion channels (ASICs), the receptors to lactic acid, was amiloride, a substance that is also a potent antagonist for both epithelial sodium channels as well as voltage-gated sodium channels. Recently, a second compound, A-317567, has been shown to be an effective and selective antagonist to ASICs in vitro. Consequently, we measured the pressor responses to the static contraction of the triceps surae muscles in decerebrate cats before and after a popliteal arterial injection of A-317567 (10 mM solution; 0.5 ml). We found that this ASIC antagonist significantly attenuated by half (Pacid injection into the popliteal artery. In contrast, A-317567 had no effect on the pressor responses to tendon stretch, a pure mechanical stimulus, and to a popliteal arterial injection of capsaicin, which stimulated transient receptor potential vanilloid type 1 channels. We conclude that ASICs on thin fiber muscle afferents play a substantial role in evoking the metabolic component of the exercise pressor reflex.

  17. Study on radiation-induced oxide-reduction of actinoid ions in acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Ishigure, Kenkichi; Katsumura, Yosuke; Hiroishi, Daisuke [Tokyo Univ. (Japan). Faculty of Engineering; and others

    1996-01-01

    Many studies have been made on the application of actinoid ion, especially UO{sub 2}{sup 2+} to change atomic valance but the mechanism of photoreduction has not yet been solved. In this study, the mechanism of photoreduction of UO{sub 2}{sup 2+} in acid solution was investigated. As functions of alcohol and acid concentrations, {phi}(U{sup IV}) was determined and photoreduction of UO{sub 2}{sup 2+} was investigated as well as NpO{sub 2}{sup 2+}. As an increase of alcohol content (EtOH, MtOH, iso-PrOH), {phi}(U{sup IV}) increased to reach a plateau ({approx}0.6). In addition, {phi}(U{sup IV}) increased linearly with an increase of acid content and the value became smaller in the order, H{sub 3}PO{sub 4}, H{sub 2}SO{sub 4}, HClO{sub 4} solution. Comparing with these results of UO{sub 2}{sup 2+}, photoreduction of NpO{sub 2}{sup 2+} was investigated. Only NpO{sub 2}{sup +} was produced as the final products, but not Np{sup IV} and NP{sup III}. Alcohol dependency of NpO{sub 2}{sup 2+} photoreduction was similar to that of UO{sub 2}{sup 2+} system but the plateau level of {phi} (NpO{sub 2}{sup 2+}) was lower ({approx}0.15) than the latter. (M.N.)

  18. Molecularly imprinted polymer-matrix nanocomposite for enantioselective electrochemical sensing of D- and L-aspartic acid.

    Science.gov (United States)

    Prasad, Bhim Bali; Srivastava, Amrita; Tiwari, Mahavir Prasad

    2013-10-01

    A new molecularly imprinted polymer-matrix (titanium dioxide nanoparticle/multiwalled carbon nanotubes) nanocomposite was developed for the modification of pencil graphite electrode as an enantioselective sensing probe for aspartic acid isomers, prevalent at ultra trace level in aqueous and real samples. The nanocomposite having many shape complementary cavities was synthesized adopting surface initiated-activators regenerated by electron transfer for atom transfer radical polymerization. The proposed sensor has high stability, nanocomposite uniformity, good reproducibility, and enhanced electrocatalytic activity to respond oxidative peak current of L-aspartic acid quantitatively by differential pulse anodic stripping voltammetry, without any cross-reactivity in real samples. Under the optimized operating conditions, the L-aspartic acid imprinted modified electrode showed a wide linear response for L-aspartic acid within the concentration range 9.98-532.72 ng mL(-1), with the minimum detection limit of 1.73-1.79 ng mL(-1) (S/N=3) in aqueous and real samples. Almost similar stringent limit (1.79 ng mL(-1)) was obtained with cerebrospinal fluid which is typical for the primitive diagnosis of neurological disorders, caused by an acute depletion of L-aspartic acid biomarker, in clinical settings. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Changes in the physiological properties and kinetics of citric acid accumulation via carbon ion irradiation mutagenesis of Aspergillus niger *

    Science.gov (United States)

    Hu, Wei; Chen, Ji-hong; Wang, Shu-yang; Liu, Jing; Song, Yuan; Wu, Qing-feng; Li, Wen-jian

    2016-01-01

    The objective of this work was to produce citric acid from corn starch using a newly isolated mutant of Aspergillus niger, and to analyze the relationship between changes in the physiological properties of A. niger induced by carbon ion irradiation and citric acid accumulation. Our results showed that the physiological characteristics of conidia in A. niger were closely related to citric acid accumulation and that lower growth rate and viability of conidia may be beneficial to citric acid accumulation. Using corn starch as a raw material, a high-yielding citric acid mutant, named HW2, was obtained. In a 10-L bioreactor, HW2 can accumulate 118.9 g/L citric acid with a residual total sugar concentration of only 14.4 g/L. This represented an 18% increase in citric acid accumulation and a 12.5% decrease in sugar utilization compared with the original strain.

  20. Retention prediction and hydrophobicity estimation of weak acidic compounds by reversed-phase liquid chromatography using acetic and perchloric acids as ion suppressors.

    Science.gov (United States)

    Han, Shu-ying; Ming, Xin; Qi, Zheng-chun; Sheng, Dong; Lian, Hong-zhen

    2010-11-01

    Simple acids are usually applied to suppress the ionization of weakly ionizable acidic analytes in reversed-phase liquid chromatography. The purpose of this study is to investigate the retention behavior of various weak acidic compounds (monoprotic, diprotic, triprotic, and tetraprotic acids) using acetic or perchloric acid as ion suppressor in a binary hydroorganic mobile phase. The apparent n-octanol-water partition coefficient (K(ow)") was proposed to calibrate the n-octanol-water partition coefficient (K(ow)) of weak acidic compound. LogK(ow)" was found to have a better linear correlation with logk(w), the logarithm of the retention factor obtained by extrapolating to neat aqueous fraction of the mobile phase, for all weakly ionizable acidic compounds. This straightforward relationship offers a potential medium for direct measurement of K(ow) data of weak acidic analytes and can be used to predict retention behavior of these compounds in the ion suppression reversed-phase liquid chromatographic mode.

  1. Quantitative assessment of the ion-beam irradiation induced direct damage of nucleic acid bases through FTIR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qing, E-mail: huangq@ipp.ac.cn [Key Laboratory of Ion Beam Bio-engineering, Institute of Technical Biology and Agriculture Engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences (China); University of Science and Technology of China, Hefei 230029, Anhui (China); Su, Xi; Yao, Guohua; Lu, Yilin; Ke, Zhigang; Liu, Jinghua; Wu, Yuejin; Yu, Zengliang [Key Laboratory of Ion Beam Bio-engineering, Institute of Technical Biology and Agriculture Engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences (China)

    2014-07-01

    Energetic particles exist ubiquitously in nature, and when they hit DNA molecules in organisms, they may induce critical biological effects such as mutation. It is however still a challenge to measure directly and quantitatively the damage imposed by the energetic ions on target DNA molecules. In this work we attempted to employ Fourier transformation infrared (FTIR) spectroscopy to assess the ion-induced direct damage of four nucleic acid bases, namely, thymine (T), cytosine (C), guanine (G), and adenine (A), which are the building blocks of DNA molecules. The samples were prepared as thin films, irradiated by argon ion-beams at raised ion fluences, and in the meantime measured by FTIR spectroscopy for the damage in a quasi-in-situ manner. It was found that the low-energy ion-beam induced radiosensitivity of the four bases shows the sequence G > T > C > A, wherein the possible mechanism was also discussed.

  2. Effects of Chlorine Ions on the Dissolution Mechanism of Cu Thin Film in Phosphoric Acid Based Solution.

    Science.gov (United States)

    Seo, Bo-Hyun; Kim, Byoung O; Seo, Jong Hyun

    2015-10-01

    The dissolution mechanisms of Cu thin film were studied with a focus on the effect of chlorine ion concentrations in mixture solutions of phosphoric and nitric acid. The dissolution behaviors of Cu thin film were investigated by using potentio-dynamic curves and impedance spectroscopy with varying chlorine ion concentrations. The copper dissolution rate decreased and as a result of this change, CuCl, salt films formed on the Cu surface in the presence of chlorine ions in the mixture solution. Such behavior was interpreted as being competitive adsorption between chlorine and nitrate ions on the copper surface. The passive oxide film on the Cu surface was further investigated in detail using X-ray photoelectron spectroscopy in both the absence and presence of differing chlorine ion concentrations.

  3. Oxidative degradation of low and intermediate level Radioactive organic wastes 2. Acid decomposition on spent Ion-Exchange resins

    International Nuclear Information System (INIS)

    Ghattas, N.K.; Eskander, S.B.

    1995-01-01

    The present work provides a simplified, effective and economic method for the chemical decomposition of radioactively contaminated solid organic waste, especially spent ion - exchange resins. The goal is to achieve volume reduction and to avoid technical problems encountered in processes used for similar purposes (incineration, pyrolysis). Factors efficiency and kinetics of the oxidation of the ion exchange resins in acid medium using hydrogen peroxide as oxidant, namely, duration of treatment and the acid to resin ratio were studied systematically on a laboratory scale. Moreover the percent composition of the off-gas evolved during the decomposition process was analysed. 3 figs., 5 tabs

  4. Oxidative degradation of low and intermediate level Radioactive organic wastes 2. Acid decomposition on spent Ion-Exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Ghattas, N K; Eskander, S B [Radioisotope dept., atomic energy authority, (Egypt)

    1995-10-01

    The present work provides a simplified, effective and economic method for the chemical decomposition of radioactively contaminated solid organic waste, especially spent ion - exchange resins. The goal is to achieve volume reduction and to avoid technical problems encountered in processes used for similar purposes (incineration, pyrolysis). Factors efficiency and kinetics of the oxidation of the ion exchange resins in acid medium using hydrogen peroxide as oxidant, namely, duration of treatment and the acid to resin ratio were studied systematically on a laboratory scale. Moreover the percent composition of the off-gas evolved during the decomposition process was analysed. 3 figs., 5 tabs.

  5. Antiviral effects of herpes simplex virus specific anti-sense nucleic acids.

    Science.gov (United States)

    Cantin, E M; Podsakoff, G; Willey, D E; Openshaw, H

    1992-01-01

    We have targeted mRNA sequences encompassing the translation initiation codon of the essential herpes simplex virus type 1 (HSV-1) IE3 gene with three kinds of anti-sense molecule. Addition of a 15mer oligodeoxyribonucleoside methylphosphonate to tissue culture cells resulted in suppression of viral replication. HSV-1 replication was also inhibited in cultured cells containing anti-sense vectors expressing transcripts complementary to the IE3 mRNA. We have also constructed a ribozyme which upon base pairing with the target IE3 mRNA induces cleavage at the predicted GUC site. A major obstacle to anti-sense studies in animals is drug delivery of preformed antisense molecules to ganglionic neurons, the site of HSV latency and reactivation. We speculate as to how this may be accomplished through carrier compounds which are taken up by nerve terminals and transported by retrograde axoplasmic flow. By the same route, HSV itself may be used as an anti-sense vector.

  6. An ion-neutral model to investigate chemical ionization mass spectrometry analysis of atmospheric molecules - application to a mixed reagent ion system for hydroperoxides and organic acids

    Science.gov (United States)

    Heikes, Brian G.; Treadaway, Victoria; McNeill, Ashley S.; Silwal, Indira K. C.; O'Sullivan, Daniel W.

    2018-04-01

    An ion-neutral chemical kinetic model is described and used to simulate the negative ion chemistry occurring within a mixed-reagent ion chemical ionization mass spectrometer (CIMS). The model objective was the establishment of a theoretical basis to understand ambient pressure (variable sample flow and reagent ion carrier gas flow rates), water vapor, ozone and oxides of nitrogen effects on ion cluster sensitivities for hydrogen peroxide (H2O2), methyl peroxide (CH3OOH), formic acid (HFo) and acetic acid (HAc). The model development started with established atmospheric ion chemistry mechanisms, thermodynamic data and reaction rate coefficients. The chemical mechanism was augmented with additional reactions and their reaction rate coefficients specific to the analytes. Some existing reaction rate coefficients were modified to enable the model to match laboratory and field campaign determinations of ion cluster sensitivities as functions of CIMS sample flow rate and ambient humidity. Relative trends in predicted and observed sensitivities are compared as instrument specific factors preclude a direct calculation of instrument sensitivity as a function of sample pressure and humidity. Predicted sensitivity trends and experimental sensitivity trends suggested the model captured the reagent ion and cluster chemistry and reproduced trends in ion cluster sensitivity with sample flow and humidity observed with a CIMS instrument developed for atmospheric peroxide measurements (PCIMSs). The model was further used to investigate the potential for isobaric compounds as interferences in the measurement of the above species. For ambient O3 mixing ratios more than 50 times those of H2O2, O3-(H2O) was predicted to be a significant isobaric interference to the measurement of H2O2 using O2-(H2O2) at m/z 66. O3 and NO give rise to species and cluster ions, CO3-(H2O) and NO3-(H2O), respectively, which interfere in the measurement of CH3OOH using O2-(CH3OOH) at m/z 80. The CO3-(H2O

  7. Optical Sensing of Aromatic Amino Acids and Dipeptides by a Crown-Ether-Functionalized Perylene Bisimide Fluorophore.

    Science.gov (United States)

    Weißenstein, Annike; Saha-Möller, Chantu R; Würthner, Frank

    2018-06-04

    The host-guest binding properties of a fluorescent perylene bisimide (PBI) receptor equipped with crown ether were studied in detail with a series of aromatic amino acids and dipeptides by UV/Vis, fluorescence and NMR spectroscopy. Fluorescence titration experiments showed that electron-rich aromatic amino acids and dipeptides strongly quench the fluorescence of the electron-poor PBI host molecule. Benesi-Hildebrand plots of fluorescence titration data confirmed the formation of host-guest complexes with 1:2 stoichiometry. Binding constants determined by global analysis of UV/Vis and fluorescence titration experiments revealed values between 10 3  m -1 and 10 5  m -1 in acetonitrile/methanol (9:1) at 23 °C. These data showed that amino acid l-Trp having an indole group and dipeptides containing this amino acid bind to the PBI receptor more strongly than other amino acids and dipeptides investigated here. For dipeptides containing l-Trp or l-Tyr, the binding strength is dependent on the distance between the ammonium group and the aromatic unit of the amino acids and dipeptides leading to a strong sensitivity for Ala-Trp dipeptide. 1D and 2D NMR experiments also corroborated 1:2 host-guest complexation and indicated formation of two diastereomeric species of host-guest complexes. The studies have shown that a properly functionalized PBI fluorophore functions as a molecular probe for the optical sensing of aromatic amino acids and dipeptides. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Novel approach to recover cobalt and lithium from spent lithium-ion battery using oxalic acid

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Xianlai; Li, Jinhui, E-mail: jinhui@tsinghua.edu.cn; Shen, Bingyu

    2015-09-15

    Highlights: • Short-cut recovery of cobalt and lithium was directly obtained using oxalic acid. • Short-cut recovery process was optimized for a high recovery rate. • Leaching process was controlled by chemical reaction. • Leaching order of the sampling LiCoO{sub 2} using oxalic acid was first proposed. - Abstract: With the booming of consumer electronics (CE) and electric vehicle (EV), a large number of spent lithium-ion battery (LIBs) have been generated worldwide. Resource depletion and environmental concern driven from the sustainable industry of CE and EV have motivated spent LIBs should be recovered urgently. However, the conventional process combined with leaching, precipitating, and filtering was quite complicated to recover cobalt and lithium from spent LIBs. In this work, we developed a novel recovery process, only combined with oxalic acid leaching and filtering. When the optimal parameters for leaching process is controlled at 150 min retention time, 95 °C heating temperature, 15 g L{sup −1} solid–liquid ratio, and 400 rpm rotation rate, the recovery rate of lithium and cobalt from spent LIBs can reach about 98% and 97%, respectively. Additionally, we also tentatively discovered the leaching mechanism of lithium cobalt oxide (LiCoO{sub 2}) using oxalic acid, and the leaching order of the sampling LiCoO{sub 2} of spent LIBs. All the obtained results can contribute to a short-cut and high-efficiency process of spent LIBs recycling toward a sound closed-loop cycle.

  9. Strong ion and weak acid analysis in severe preeclampsia: potential clinical significance.

    Science.gov (United States)

    Ortner, C M; Combrinck, B; Allie, S; Story, D; Landau, R; Cain, K; Dyer, R A

    2015-08-01

    The influence of common disturbances seen in preeclampsia, such as changes in strong ions and weak acids (particularly albumin) on acid-base status, has not been fully elucidated. The aims of this study were to provide a comprehensive acid-base analysis in severe preeclampsia and to identify potential new biological predictors of disease severity. Fifty women with severe preeclampsia, 25 healthy non-pregnant- and 46 healthy pregnant controls (26-40 weeks' gestation), were enrolled in this prospective case-control study. Acid-base analysis was performed by applying the physicochemical approach of Stewart and Gilfix. Mean [sd] base excess was similar in preeclamptic- and healthy pregnant women (-3.3 [2.3], and -2.8 [1.5] mEq/L respectively). In preeclampsia, there were greater offsetting contributions to the base excess, in the form of hyperchloraemia (BE(Cl) -2 [2.3] vs -0.4 [2.3] mEq/L, Palkalosis was associated with a non-reassuring/abnormal fetal heart tracing (Prespiratory and hypoalbuminaemic alkalosis that was metabolically offset by acidosis, secondary to unmeasured anions and dilution. While the overall base excess in severe preeclampsia is similar to that in healthy pregnancy, preeclampsia is associated with a greater imbalance offsetting hypoalbuminaemic alkalosis and hyperchloraemic acidosis. Rather than the absolute value of base excess, the magnitude of these opposing contributors may be a better indicator of the severity of this disease. Hypoalbuminaemic alkalosis may also be a predictor of fetal compromise. clinicaltrials.gov: NCT 02164370. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Grafting of acrylic acid on etched latent tracks induced by swift heavy ions on polypropylene films

    International Nuclear Information System (INIS)

    Mazzei, R.; Fernandez, A.; Garcia Bermudez, G.; Torres, A.; Gutierrez, M.C.; Magni, M.; Celma, G.; Tadey, D.

    2008-01-01

    In order to continue with a systematic study that include different polymers and monomers, the residual active sites produced by heavy ion beams, that remain after the etching process, were used to start the grafting process. To produce tracks, foils of polypropylene (PP) were irradiated with 208 Pb of 25.62 MeV/n. Then, these were etched and grafted with acrylic acid (AA) monomers. Experimental curves of grafting yield as a function of grafting time with the etching time as a parameter were measured. Also, the grating yield as a function of the fluence and etching time was obtained. In addition, the permeation of solutions, with different pH, through PP grafted foils was measured

  11. Cesium removal from liquid acidic wastes with the primary focus on ammonium molybdophosphate as an ion exchanger: A literature review

    International Nuclear Information System (INIS)

    Miller, C.J.

    1995-03-01

    Many articles have been written concerning the selective removal of cesium from both acidic and alkaline defense wastes. The majority of the work performed for cesium removal from defense wastes involves alkaline feed solutions. Several different techniques for cesium removal from acidic solutions have been evaluated such as precipitation, solvent extraction, and ion exchange. The purpose of this paper is to briefly review various techniques for cesium removal from acidic solutions. The main focus of the review will be on ion exchange techniques, particularly those involving ammonium molybdophosphate as the exchanger. The pertinent literature sources are condensed into a single document for quick reference. The information contained in this document was used as an aid in determining techniques to evaluate cesium removal from the acidic Idaho Chemical Processing Plant waste matrices. 47 refs., 2 tabs

  12. Salinity and Salicylic Acid Interactions in Affecting Nitrogen Assimilation, Enzyme Activity, Ions Content and Translocation Rate of Maize Plants

    International Nuclear Information System (INIS)

    Khodary, S.E.A.; Moussa, H.R.

    2002-01-01

    This study was carried out to establish the relationship between nitrogen metabolism, enzyme activity, ions concentration as well as the translocation rate (TR) of carbohydrates and salicylic acid (SA) in salt-stressed maize (Zea mays L). Salicylic acid plus salinity treatment highly significantly increased: nucleic acids (DNA and RNA), protein content, phosphoenolpyruvate carboxylase (PEPCase) and nitrate reductase (NR) and inhibited nucleases (DNase and RNase) activities compared with Na CI-treated plants. In addition, the ionic levels of potassium (K), phosphorus (P), nitrate (NO 3 ) and the translocation rate of the labelled photo assimilates have also been stimulated while sodium (Na) ions content was decreased. It is concluded that, salinazid maize plants might show an enhancement in their growth pattern upon salicylic acid application

  13. Presynaptic (Type III) cells in mouse taste buds sense sour (acid) taste.

    Science.gov (United States)

    Huang, Yijen A; Maruyama, Yutaka; Stimac, Robert; Roper, Stephen D

    2008-06-15

    Taste buds contain two types of cells that directly participate in taste transduction - receptor (Type II) cells and presynaptic (Type III) cells. Receptor cells respond to sweet, bitter and umami taste stimulation but until recently the identity of cells that respond directly to sour (acid) tastants has only been inferred from recordings in situ, from behavioural studies, and from immunostaining for putative sour transduction molecules. Using calcium imaging on single isolated taste cells and with biosensor cells to identify neurotransmitter release, we show that presynaptic (Type III) cells specifically respond to acid taste stimulation and release serotonin. By recording responses in cells isolated from taste buds and in taste cells in lingual slices to acetic acid titrated to different acid levels (pH), we also show that the active stimulus for acid taste is the membrane-permeant, uncharged acetic acid moiety (CH(3)COOH), not free protons (H(+)). That observation is consistent with the proximate stimulus for acid taste being intracellular acidification, not extracellular protons per se. These findings may also have implications for other sensory receptors that respond to acids, such as nociceptors.

  14. Poly-dopamine-beta-cyclodextrin: A novel nanobiopolymer towards sensing of some amino acids at physiological pH

    International Nuclear Information System (INIS)

    Hasanzadeh, Mohammad; Sadeghi, Sattar; Bageri, Leyla; Mokhtarzadeh, Ahad; Karimzadeh, Ayub; Shadjou, Nasrin; Mahboob, Soltanali

    2016-01-01

    A novel nanobiopolymer film was electrodeposited on the surface of glassy carbon through cyclic voltammetry from dopamine, β-cyclodextrin, and phosphate buffer solution in physiological pH (7.40). The electrochemical behavior of polydopamine-Beta-cyclodextrin modified glassy carbon electrode was investigated for electro-oxidation and determination of some amino acids (L-Cysteine, L-Tyrosine, L-Glycine, and L-Phenylalanine). The modified electrode was applied for selected amino acid detection at physiological pH using cyclic voltammetry, differential pulse voltammetry and chronoamperometry, chronocoulometery. The linear concentration range of the proposed sensor for the L-Glycine, L-Cysteine, L-Tyrosine, and L-Phenylalanine were 0.2–70, 0.06–0.2, 0.01–0.1, and 0.2–10 μM, while low limit of quantifications were 0.2, 0.06, 0.01, and 0.2 μM, respectively. The modified electrode shows many advantages as an amino acid sensor such as simple preparation method without using any specific electron transfer mediator or specific reagent, good sensitivity, short response time, and long term stability. - Highlights: • A novel biopolymer film with entitled PDA-β-CD was electrodeposited on the GCE. • Synergetic effect of β-CD and GQD on the electrical signal amplifications was investigated. • The performance of β-CD-GQD-GCE towards electrochemical sensing of some amino acids was investigated.

  15. Poly-dopamine-beta-cyclodextrin: A novel nanobiopolymer towards sensing of some amino acids at physiological pH

    Energy Technology Data Exchange (ETDEWEB)

    Hasanzadeh, Mohammad, E-mail: mhmmd_hasanzadeh@yahoo.com [Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of); Pharmaceutical Analysis Research Center, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of); Sadeghi, Sattar [Department of Biochemistry, Higher Education Institute of Rab-Rashid, Tabriz (Iran, Islamic Republic of); Bageri, Leyla [Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of); Mokhtarzadeh, Ahad [School of Medicine, Gonabad University of Medical Sciences, Gonabad (Iran, Islamic Republic of); Department of Biochemistry, Higher Education Institute of Rab-Rashid, Tabriz (Iran, Islamic Republic of); Karimzadeh, Ayub [Department of Biochemistry, Higher Education Institute of Rab-Rashid, Tabriz (Iran, Islamic Republic of); Shadjou, Nasrin [Department of Nanochemistry, Nano Technology Research Center, Urmia University, Urmia 57154 (Iran, Islamic Republic of); Department of Nano Technology, Faculty of Science, Urmia University, Urmia 57154 (Iran, Islamic Republic of); Mahboob, Soltanali [Department of Biochemistry, Higher Education Institute of Rab-Rashid, Tabriz (Iran, Islamic Republic of)

    2016-12-01

    A novel nanobiopolymer film was electrodeposited on the surface of glassy carbon through cyclic voltammetry from dopamine, β-cyclodextrin, and phosphate buffer solution in physiological pH (7.40). The electrochemical behavior of polydopamine-Beta-cyclodextrin modified glassy carbon electrode was investigated for electro-oxidation and determination of some amino acids (L-Cysteine, L-Tyrosine, L-Glycine, and L-Phenylalanine). The modified electrode was applied for selected amino acid detection at physiological pH using cyclic voltammetry, differential pulse voltammetry and chronoamperometry, chronocoulometery. The linear concentration range of the proposed sensor for the L-Glycine, L-Cysteine, L-Tyrosine, and L-Phenylalanine were 0.2–70, 0.06–0.2, 0.01–0.1, and 0.2–10 μM, while low limit of quantifications were 0.2, 0.06, 0.01, and 0.2 μM, respectively. The modified electrode shows many advantages as an amino acid sensor such as simple preparation method without using any specific electron transfer mediator or specific reagent, good sensitivity, short response time, and long term stability. - Highlights: • A novel biopolymer film with entitled PDA-β-CD was electrodeposited on the GCE. • Synergetic effect of β-CD and GQD on the electrical signal amplifications was investigated. • The performance of β-CD-GQD-GCE towards electrochemical sensing of some amino acids was investigated.

  16. Analysis of trace inorganic anions in weak acid salts by single pump cycling-column-switching ion chromatography.

    Science.gov (United States)

    Huang, Zhongping; Ni, Chengzhu; Zhu, Zhuyi; Pan, Zaifa; Wang, Lili; Zhu, Yan

    2015-05-01

    The application of ion chromatography with the single pump cycling-column-switching technique was described for the analysis of trace inorganic anions in weak acid salts within a single run. Due to the hydrogen ions provided by an anion suppressor electrolyzing water, weak acid anions could be transformed into weak acids, existing as molecules, after passing through the suppressor. Therefore, an anion suppressor and ion-exclusion column were adopted to achieve on-line matrix elimination of weak acid anions with high concentration for the analysis of trace inorganic anions in weak acid salts. A series of standard solutions consisting of target anions of various concentrations from 0.005 to 10 mg/L were analyzed, with correlation coefficients r ≥ 0.9990. The limits of detection were in the range of 0.67 to 1.51 μg/L, based on the signal-to-noise ratio of 3 and a 25 μL injection volume. Relative standard deviations for retention time, peak area, and peak height were all less than 2.01%. A spiking study was performed with satisfactory recoveries between 90.3 and 104.4% for all anions. The chromatographic system was successfully applied to the analysis of trace inorganic anions in five weak acid salts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Studies of endothelial monolayer formation on irradiated poly-L-lactide acid with ions of different stopping power and velocity

    Energy Technology Data Exchange (ETDEWEB)

    Arbeitman, Claudia R. [CONICET – Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Gerencia de Investigación y Aplicaciones, TANDAR-CNEA (Argentina); UNQ – IMBICE – CCT – CONICET – LA PLATA (Argentina); Grosso, Mariela F. del [CONICET – Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Gerencia de Investigación y Aplicaciones, TANDAR-CNEA (Argentina); Ibañez, Irene L. [CONICET – Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina); Behar, Moni [Instituto de Física, UFRGS, Porto Alegre, RS (Brazil); Grasselli, Mariano [UNQ – IMBICE – CCT – CONICET – LA PLATA (Argentina); Bermúdez, Gerardo García [Gerencia de Investigación y Aplicaciones, TANDAR-CNEA (Argentina)

    2015-12-15

    In this work we study cell viability, proliferation and morphology of bovine aortic endothelial cells (BAEC) cultured on poly-L-lactide acid (PLLA) modified by heavy ion irradiation. In a previous study comparing ions beams with the same stopping power we observed an increase in cell density and a better cell morphology at higher ion velocities. In the present work we continued this study using heavy ions beam with different stopping power and ion velocities. To this end thin films of 50 μm thickness were irradiated with 2 MeV/u and 0.10 MeV/u ion beams provided the Tandar (Buenos Aires, Argentina) and Tandetron (Porto Alegre, Brazil) accelerators, respectively. The results suggest that a more dense and elongated cell shapes, similar to the BAEC cells on the internal surface of bovine aorta, was obtained for stopping power of 18.2–22.1 MeV cm{sup 2} mg{sup −1} and ion velocity of 2 MeV/u. On the other hand, for low ion velocity 0.10 MeV/u the cells present a more globular shapes.

  18. Studies of endothelial monolayer formation on irradiated poly-L-lactide acid with ions of different stopping power and velocity

    International Nuclear Information System (INIS)

    Arbeitman, Claudia R.; Grosso, Mariela F. del; Ibañez, Irene L.; Behar, Moni; Grasselli, Mariano; Bermúdez, Gerardo García

    2015-01-01

    In this work we study cell viability, proliferation and morphology of bovine aortic endothelial cells (BAEC) cultured on poly-L-lactide acid (PLLA) modified by heavy ion irradiation. In a previous study comparing ions beams with the same stopping power we observed an increase in cell density and a better cell morphology at higher ion velocities. In the present work we continued this study using heavy ions beam with different stopping power and ion velocities. To this end thin films of 50 μm thickness were irradiated with 2 MeV/u and 0.10 MeV/u ion beams provided the Tandar (Buenos Aires, Argentina) and Tandetron (Porto Alegre, Brazil) accelerators, respectively. The results suggest that a more dense and elongated cell shapes, similar to the BAEC cells on the internal surface of bovine aorta, was obtained for stopping power of 18.2–22.1 MeV cm 2 mg −1 and ion velocity of 2 MeV/u. On the other hand, for low ion velocity 0.10 MeV/u the cells present a more globular shapes.

  19. Monitoring responses of Mason Pine to acid rain in China based on remote sensing vegetation index

    International Nuclear Information System (INIS)

    Jin, Jiaxin; Jiang, Hong; Zhang, Xiuying; Wang, Ying; Hou, Chunliang

    2014-01-01

    Since the 1970s, acid rain has remained in the public spotlight in both Europe and the United States and recently has emerged as an important problem in other regions such as Southeast Asia. To reveal responses of Masson Pine to acid rain during a long time series in central China, we used the interpolation dataset of acid rain and the Global Inventory Modeling and Mapping Studies (GIMMS) normalized difference vegetation index (NDVI) data to derive the monthly pH and NDVI trajectories based on acidity gradients from 1992 to 2006. Then we analyzed inter-annual and seasonal variation of vegetation growth by improved sinusoidal fitting and regression analysis. In the environment of strong acidity and moderate acidity, the growth of Masson Pine was inhibited during the study period, while the slight acidity promoted growth of Masson Pine to some extent. For the multi-year monthly changing trend of NDVI, late spring to mid autumn, the NDVI showed a decreasing trend, especially in June, while from late autumn to the following spring, the NDVI showed a rising tendency, specifically in December and March

  20. Role of FAT/CD36 in fatty acid sensing, energy, and glucose homeostasis regulation in DIO and DR rats.

    Science.gov (United States)

    Le Foll, Christelle; Dunn-Meynell, Ambrose A; Levin, Barry E

    2015-02-01

    Hypothalamic fatty acid (FA) sensing neurons alter their activity utilizing the FA translocator/receptor, FAT/CD36. Depletion of ventromedial hypothalamus (VMH) CD36 with adeno-associated viral vector expressing CD36 shRNA (AAV CD36 shRNA) leads to redistribution of adipose stores and insulin resistance in outbred rats. This study assessed the requirement of VMH CD36-mediated FA sensing for the regulation of energy and glucose homeostasis in postnatal day 5 (P5) and P21 selectively bred diet-induced obese (DIO) and diet-resistant (DR) rats using VMH AAV CD36 shRNA injections. P5 CD36 depletion altered VMH neuronal FA sensing predominantly in DIO rats. After 10 wk on a 45% fat diet, DIO rats injected with VMH AAV CD36 shRNA at P21 ate more and gained more weight than DIO AAV controls, while DR AAV CD36 shRNA-injected rats gained less weight than DR AAV controls. VMH CD36 depletion increased inguinal fat pad weights and leptin levels in DIO and DR rats. Although DR AAV CD36 shRNA-injected rats became as obese as DIO AAV controls, only DIO control and CD36 depleted rats became insulin-resistant on a 45% fat diet. VMH CD36 depletion stunted linear growth in DIO and DR rats. DIO rats injected with AAV CD36 shRNA at P5 had increased fat mass, mostly due to a 45% increase in subcutaneous fat. They were also insulin-resistant with an associated 71% increase of liver triglycerides. These results demonstrate that VMH CD36-mediated FA sensing is a critical factor in the regulation of energy and glucose homeostasis and fat deposition in DIO and DR rats.

  1. Distribution of Components in Ion Exchange Materials Taken from the K East Basin and Leaching of Ion Exchange Materials by Nitric/Hydrofluoric Acid and Nitric/Oxalic Acid

    International Nuclear Information System (INIS)

    Delegard, C.H.; Rinehart, D.E.; Hoopes, F.V.

    1998-01-01

    Laboratory tests were performed to examine the efficacy of mixed nitric/hydrofluoric acid followed by mixed nitric/oxalic acid leach treatments to decontaminate ion exchange materials that have been found in a number of samples retrieved from K East (KE)Basin sludge. The ion exchange materials contain organic ion exchange resins and zeolite inorganic ion exchange material. Based on process records, the ion exchange resins found in the K Basins is a mixed-bed, strong acid/strong base material marketed as Purolite NRW-037. The zeolite material is Zeolon-900, a granular material composed of the mineral mordenite. Radionuclides sorbed or associated with the ion exchange material can restrict its disposal to the Environmental Restoration Disposal Facility (ERDF). The need for testing to support development of a treatment process for K Basin sludge has been described in Section 4.2 of ''Testing Strategy to Support the Development of K Basins Sludge Treatment Process'' (Flament 1998). Elutriation and washing steps are designed to remove the organic resins from the K Basin sludge. To help understand the effects of the anticipated separation steps, tests were performed with well-rinsed ion exchange (IX) material from KE Basin floor sludge (sample H-08 BEAD G) and with well-rinsed IX having small quantities of added KE canister composite sludge (sample KECOMP). Tests also were performed to determine the relative quantities of organic and inorganic IX materials present in the H-08 K Basin sludge material. Based on chemical analyses of the separated fractions, the rinsed and dry IX material H-08 BEAD G was found to contain 36 weight percent inorganic material (primarily zeolite). The as-received (unrinsed) and dried H-08 material was estimated to contain 45 weight percent inorganic material

  2. Synthesis of ion exchange membrane by radiation grafting of acrylic acid onto polyethylene

    International Nuclear Information System (INIS)

    Ishigaki, I.; Sugo, T.; Senoo, K.; Takayama, T.; Machi, S.; Okamoto, J.; Okada, T.

    1981-01-01

    Radiation grafting of vinyl monomers onto polymer films has been extensively studied by many workers. In the preirradiation method of grafting a polymer substrate is activated by irradiation (either in the presence or absence of oxygen) and subsequently allowed to react with a monomer. The preirradiation method was utilized in this study to synthesize an ion exchange membrane useful for a battery separator by grafting acrylic acid onto polyethylene film. The battery separator should be chemically and thermally stable, sufficiently durable in electrolyte as well as highly electrically conductive. Membranes made from regenerated cellulose, e.g., cellophane, have long been used as a separator in the batteries with alkaline electrolyte, such as silver oxide primary cell. However, it has poor durability, as short as one year, due to breakdown of the membrane during operation or storing. The acrylic acid-grafted polyethylene film was found to be quite useful for a separator in the alkaline batteries. This membrane has a high electric conductivity and an excellent durability. (author)

  3. Ion balance and acidity of size-segregated particles during haze episodes in urban Beijing

    Science.gov (United States)

    Tian, Shili; Pan, Yuepeng; Wang, Yuesi

    2018-03-01

    In this study, we investigated how the ion balance causes variations in size segregated aerosol acidity and atmospheric processing on clean versus hazy days using a 9-stage sampler. We calculated the ratios (in charge equivalents, RC/A) between measured cations (Na+, NH4+, K+, Mg2 +, and Ca2 +) and anions (SO42 -, NO3- and Cl-) for different aerosol size fractions. The ratios were typically close to unity in the accumulation mode (0.65-2.1 μm), and increased significantly when the particle size increased or decreased. In the coarse size range (aerodynamic diameter > 2.1 μm), high RC/A values were most likely caused by the undetermined CO32- and HCO3- content of the mineral dust. In contrast, the high RC/A values for submicron aerosols (NH4+ (SNA) and concentrations of SNA increased with the increasing aerosol acidity. Significant correlations between [NO3-]/[SO42 -] and [NH4+]/[SO42 -] during NH4+-rich conditions in fine size fractions indicated fine mode NO3- in Beijing was mainly formed by gas-phase homogeneous reaction between the ambient NH3 and HNO3.

  4. Novel approach to recover cobalt and lithium from spent lithium-ion battery using oxalic acid.

    Science.gov (United States)

    Zeng, Xianlai; Li, Jinhui; Shen, Bingyu

    2015-09-15

    With the booming of consumer electronics (CE) and electric vehicle (EV), a large number of spent lithium-ion battery (LIBs) have been generated worldwide. Resource depletion and environmental concern driven from the sustainable industry of CE and EV have motivated spent LIBs should be recovered urgently. However, the conventional process combined with leaching, precipitating, and filtering was quite complicated to recover cobalt and lithium from spent LIBs. In this work, we developed a novel recovery process, only combined with oxalic acid leaching and filtering. When the optimal parameters for leaching process is controlled at 150 min retention time, 95 °C heating temperature, 15 g L(-1) solid-liquid ratio, and 400 rpm rotation rate, the recovery rate of lithium and cobalt from spent LIBs can reach about 98% and 97%, respectively. Additionally, we also tentatively discovered the leaching mechanism of lithium cobalt oxide (LiCoO2) using oxalic acid, and the leaching order of the sampling LiCoO2 of spent LIBs. All the obtained results can contribute to a short-cut and high-efficiency process of spent LIBs recycling toward a sound closed-loop cycle. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Optical Sensing Properties of Pyrene-Schiff Bases toward Different Acids.

    Science.gov (United States)

    Babgi, Bandar A; Alzahrani, Asma

    2016-07-01

    A set of (4-substituted-phenyl)-pyren-1-ylmethylene-amine (PMA) was prepared by the reaction of pyrene-1-carboxaldehyde and the corresponding 4-substituted aniline. The structure of the PMA compounds were confirmed by spectroscopic data (IR, (1)HNMR, (13)CNMR, ISI-MS and elemental analysis. The structure of (4-bromo-phenyl)-pyren-1-ylmethylene-amine (BrPMA) was further confirmed by the single X-ray crystallography. The absorption and emission spectroscopic behaviors were investigated in variant acids. The compounds showed dramatic spectroscopic changes upon acidifying with strong acids and negligible effects when weak acids are used in the acidifications. Hence, the PMA compounds can be used as sensors to distinguish between weak and strong acids.

  6. Niflumic acid alters gating of HCN2 pacemaker channels by interaction with the outer region of S4 voltage sensing domains.

    Science.gov (United States)

    Cheng, Lan; Sanguinetti, Michael C

    2009-05-01

    Niflumic acid, 2-[[3-(trifluoromethyl)phenyl]amino]pyridine-3-carboxylic acid (NFA), is a nonsteroidal anti-inflammatory drug that also blocks or modifies the gating of many ion channels. Here, we investigated the effects of NFA on hyperpolarization-activated cyclic nucleotide-gated cation (HCN) pacemaker channels expressed in X. laevis oocytes using site-directed mutagenesis and the two-electrode voltage-clamp technique. Extracellular NFA acted rapidly and caused a slowing of activation and deactivation and a hyperpolarizing shift in the voltage dependence of HCN2 channel activation (-24.5 +/- 1.2 mV at 1 mM). Slowed channel gating and reduction of current magnitude was marked in oocytes treated with NFA, while clamped at 0 mV but minimal in oocytes clamped at -100 mV, indicating the drug preferentially interacts with channels in the closed state. NFA at 0.1 to 3 mM shifted the half-point for channel activation in a concentration-dependent manner, with an EC(50) of 0.54 +/- 0.068 mM and a predicted maximum shift of -38 mV. NFA at 1 mM also reduced maximum HCN2 conductance by approximately 20%, presumably by direct block of the pore. The rapid onset and state-dependence of NFA-induced changes in channel gating suggests an interaction with the extracellular region of the S4 transmembrane helix, the primary voltage-sensing domain of HCN2. Neutralization (by mutation to Gln) of any three of the outer four basic charged residues in S4, but not single mutations, abrogated the NFA-induced shift in channel activation. We conclude that NFA alters HCN2 gating by interacting with the extracellular end of the S4 voltage sensor domains.

  7. Contact ion pair formation between hard acids and soft bases in aqueous solutions observed with 2DIR spectroscopy.

    Science.gov (United States)

    Sun, Zheng; Zhang, Wenkai; Ji, Minbiao; Hartsock, Robert; Gaffney, Kelly J

    2013-12-12

    The interaction of charged species in aqueous solution has important implications for chemical, biological, and environmental processes. We have used 2DIR spectroscopy to study the equilibrium dynamics of thiocyanate chemical exchange between free ion (NCS(-)) and contact ion pair configurations (MNCS(+)), where M(2+) = Mg(2+) or Ca(2+). Detailed studies of the influence of anion concentration and anion speciation show that the chemical exchange observed with the 2DIR measurements results from NCS(-) exchanging with other anion species in the first solvation shell surrounding Mg(2+) or Ca(2+). The presence of chemical exchange in the 2DIR spectra provides an indirect, but robust, determinant of contact ion pair formation. We observe preferential contact ion pair formation between soft Lewis base anions and hard Lewis acid cations. This observation cannot be easily reconciled with Pearson's acid-base concept or Collins' Law of Matching Water Affinities. The anions that form contact ion pairs also correspond to the ions with an affinity for water and protein surfaces, so similar physical and chemical properties may control these distinct phenomena.

  8. Direct analysis of volatile fatty acids in marine sediment porewater by two-dimensional ion chromatography-mass spectrometry

    DEFF Research Database (Denmark)

    Glombitza, Clemens; Pedersen, Jeanette; Røy, Hans

    2014-01-01

    Volatile fatty acids (VFAs) are key intermediates in the microbial food web. However, the analysis of low concentrations of VFAs in marine porewater is hampered by interference from high concentrations of inorganic ions. Published methods often use sample pretreatment, including distillation or d...

  9. SOLVENT EFFECTS IN THE LIQUID-PHASE HYDRATION OF CYCLOHEXENE CATALYZED BY A MACROPOROUS STRONG ACID ION-EXCHANGE RESIN

    NARCIS (Netherlands)

    PANNEMAN, HJ; BEENACKERS, AACM

    1992-01-01

    The liquid-phase hydration of cyclohexene, a pseudo first order reversible reaction catalyzed by a strong acid ion exchange resin, macroporous Amberlite XE 307, was investigated in solvent mixtures of water and sulfolane. A decrease by a factor of 3 and 6 is observed in the experimentally measured

  10. SYNTHESIS OF METHYL TERT-BUTYL ETHER CATALYZED BY ACIDIC ION-EXCHANGE RESINS - INFLUENCE OF THE PROTON ACTIVITY

    NARCIS (Netherlands)

    PANNEMAN, HJ; BEENACKERS, AACM

    1995-01-01

    The catalytic activity of various strong acid ion-exchange resins on the synthesis of methyl tert-butyl ether (MtBE) from methanol and isobutene has been investigated. Relative to Amberlyst 15, Kastel CS 381 and Amberlyst CSP have similar rate constants, whereas Duolite ES 276 and Amberlyst XE 307

  11. Measuring Gas-Phase Basicities of Amino Acids Using an Ion Trap Mass Spectrometer: A Physical Chemistry Laboratory Experiment

    Science.gov (United States)

    Sunderlin, Lee S.; Ryzhov, Victor; Keller, Lanea M. M.; Gaillard, Elizabeth R.

    2005-01-01

    An experiment is performed to measure the relative gas-phase basicities of a series of five amino acids to compare the results to literature values. The experiments use the kinetic method for deriving ion thermochemistry and allow students to perform accurate measurements of thermodynamics in a relatively short time.

  12. Ion-exchange Resin Catalyzed Esterification of Lactic Acid with Isopropanol: a Kinetic Study

    Directory of Open Access Journals (Sweden)

    Amrit P. Toor

    2011-05-01

    Full Text Available The kinetic behavior of esterification of lactic acid with isopropanol over an acidic cation exchange resin, Amberlyst 15, was studied under isothermal condition. Isopropyl lactate synthesized in this reaction is an important pharmaceutical intermediate. The experiments were carried out in a stirred batch reactor in the temperature range of 323.15 to 353.15 K. The effect of various parameters such as temperature, molar ratio and catalyst loading was studied. Variation in parameters on rate of reaction demonstrated that the reaction was intrinsically controlled. Kinetic modeling was performed using Eley-Rideal model which acceptably fits the experimental data. The activation energy was found to be 22.007 kJ/mol and frequency factor was 0.036809 l2 g-1 mol-1 min-1 for forward reaction. The value of entropy for the forward reaction was found to be 182.317 J K-1 mol-1 . © 2011 BCREC UNDIP. All rights reserved(Received: 19th January 2011, Revised: 16th March 2011; Accepted: 16th March 2011[How to Cite: A.P. Toor, M. Sharma, S. Thakur, and R. K. Wanchoo. (2011. Ion-exchange Resin Catalyzed Esterification of Lactic Acid with Isopropanol: a Kinetic Study. Bulletin of Chemical Reaction Engineering and Catalysis, 6(1: 39-45. doi:10.9767/bcrec.6.1.791.39-45][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.791.39-45 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/791 ] | View in  

  13. Improved separation of conjugated fatty acid methyl esters by silver ion-high-performance liquid chromatography.

    Science.gov (United States)

    Sehat, N; Rickert, R; Mossoba, M M; Kramer, J K; Yurawecz, M P; Roach, J A; Adlof, R O; Morehouse, K M; Fritsche, J; Eulitz, K D; Steinhart, H; Ku, Y

    1999-04-01

    Operating from one to six silver ion-high-performance liquid chromatography (Ag+-HPLC) columns in series progressively improved the resolution of the methyl esters of conjugated linoleic acid (CLA) isomeric mixtures from natural and commercial products. In natural products, the 8 trans, 10 cis-octadecadienoic (18:2) acid was resolved from the more abundant 7 trans, 9 cis-18:2, and the 10 trans, 12 cis-18:2 was separated from the major 9 cis, 11 trans-18:2 peak. In addition, both 11 trans, 13 cis-18:2 and 11 cis, 13 trans-18:2 isomers were found in natural products and were separated; the presence of the latter, 11 cis, 13 trans-18:2, was established in commercial CLA preparations. Three Ag+-HPLC columns in series appeared to be the best compromise to obtain satisfactory resolution of most CLA isomers found in natural products. A single Ag+-HPLC column in series with one of several normal-phase columns did not improve the resolution of CLA isomers as compared to that of the former alone. The 20:2 conjugated fatty acid isomers 11 cis, 13 trans-20:2 and 12 trans, 14 cis-20:2, which were synthesized by alkali isomerization from 11 cis, 14 cis-20:2, eluted in the same region of the Ag+-HPLC chromatogram just before the corresponding geometric CLA isomers. Therefore, CLA isomers will require isolation based on chain length prior to Ag+-HPLC separation. The positions of conjugated double bonds in 20:2 and 18:2 isomers were established by gas chromatography-electron ionization mass spectrometry as their 4,4-dimethyloxazoline derivatives. The double-bond geometry was determined by gas chromatography-direct deposition-Fourier transform infrared spectroscopy and by the Ag+-HPLC relative elution order.

  14. Retention of metal and sulphate ions from acidic mining water by anionic nanofibrillated cellulose.

    Science.gov (United States)

    Venäläinen, Salla H; Hartikainen, Helinä

    2017-12-01

    We carried out an adsorption experiment to investigate the ability of anionic nanofibrillated cellulose (NFC) to retain metal and SO 4 2- ions from authentic highly acidic (pH3.2) mining water. Anionic NFC gels of different consistencies (1.1-%, 1.4-% and 1.8-% w/w) were allowed to react for 10min with mining water, after which NFC-induced changes in the metal and SO 4 2- concentrations of the mining water were determined. The sorption capacities of the NFC gels were calculated as the difference between the element concentrations in the untreated and NFC-treated mining water samples. All the NFCs efficiently co-adsorbed both metals and SO 4 2- . The retention of metals was concluded to take place through formation of metal-ligand complexes. The reaction between the NFC ligand and the polyvalent cations renders the cellulose nanofibrils positively charged and, thus, able to retain SO 4 2- electrostatically. Adsorption capacity of the NFC gels substantially increased upon decreasing DM content as a result of the dilution-induced weakening of the mutual interactions between individual cellulose nanofibrils. This outcome reveals that the dilution of the NFC gel not only increases its purification capacity but also reduces the demand for cellulosic raw material. These results suggest that anionic NFC made of renewable materials serves as an environmentally sound and multifunctional purification agent for acidic multimetal mining waters or AMDs of high ionic strength. Unlike industrial minerals traditionally used to precipitate valuable metals from acidic mining effluents before their permanent disposal from the material cycle, NFC neither requires mining of unrenewable raw materials nor produces inorganic sludges. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Oxidative degradation of acid doped polybenzimidazole membranes and fuel cell durability in the presence of ferrous ions

    DEFF Research Database (Denmark)

    Liao, Jianhui; Yang, Jingshuai; Li, Qingfeng

    2013-01-01

    Phosphoric acid doped polybenzimidazole membranes have been explored as proton exchange membranes for high temperature polymer electrolyte membrane fuel cells. Long-term durability of the membrane is of critical concern and has been evaluated by accelerated degradation tests under Fenton conditions...... of the polymer. Fuel cell durability tests with contaminations of ferrous ions did show considerable performance degradation, however, primarily due to the catalyst deterioration rather than the membrane degradation........ In this study effects of phosphoric acid and ferrous ions were investigated by measurements of the weight loss, intrinsic viscosity and size exclusion chromatography (SEC) of the polymer membranes. Ferrous ions resulted in, as expected, catalytic formation of peroxide radicals and hence the accelerated polymer...

  16. Production of citric acid using its extraction wastewater treated by anaerobic digestion and ion exchange in an integrated citric acid-methane fermentation process.

    Science.gov (United States)

    Xu, Jian; Chen, Yang-Qiu; Zhang, Hong-Jian; Tang, Lei; Wang, Ke; Zhang, Jian-Hua; Chen, Xu-Sheng; Mao, Zhong-Gui

    2014-08-01

    In order to solve the problem of extraction wastewater pollution in citric acid industry, an integrated citric acid-methane fermentation process is proposed in this study. Extraction wastewater was treated by mesophilic anaerobic digestion and then used to make mash for the next batch of citric acid fermentation. The recycling process was done for seven batches. Citric acid production (82.4 g/L on average) decreased by 34.1 % in the recycling batches (2nd-7th) compared with the first batch. And the residual reducing sugar exceeded 40 g/L on average in the recycling batches. Pigment substances, acetic acid, ammonium, and metal ions in anaerobic digestion effluent (ADE) were considered to be the inhibitors, and their effects on the fermentation were studied. Results indicated that ammonium, Na(+) and K(+) in the ADE significantly inhibited citric acid fermentation. Therefore, the ADE was treated by acidic cation exchange resin prior to reuse to make mash for citric acid fermentation. The recycling process was performed for ten batches, and citric acid productions in the recycling batches were 126.6 g/L on average, increasing by 1.7 % compared with the first batch. This process could eliminate extraction wastewater discharge and reduce water resource consumption.

  17. Separation of uranium and other metals from commercial phosphoric acid by ion-exchange and voltammetric determination of uranium

    International Nuclear Information System (INIS)

    Ferreira, J.B.C.; Carvalho, F.M.S. de; Abrao, A.

    1985-11-01

    The separation of metals from crude commercial phosphoric acid is achieved by simple dilution and percolation through a strong cationic ion exchanger. Uranium, calcium, magnesium, manganese, iron and aluminum are quantitatively fixed by the exchanger and can be detected or analysed after their complete elution with 6 M HCI. Titanium and zirconium are only partially retained. Specially for its separation and determination uranium is retained selectively by the resin from the phosphoric acid-EDTA solution, the column is washed with water and then eluted with hydrochloric acid. Uranium is analyzed by voltametry with the hanging drop mercury electrode. (Author) [pt

  18. Extraction of Trivalent La, Nd and Eu from Nitric Acid Solution by Ion quest-801 Loaded on Lewatit CA 9221

    International Nuclear Information System (INIS)

    Nowier, H.G; Metwally, S.S; Abd El-Rehim, S.S; Aly, H.F.

    2005-01-01

    The extraction of La 3+ , Nd 3+ and Eu 3+ from nitric acid medium by Lewatit CA 9221, Containing 2-ethylhexyl mono -2- ethylhexyl phosphonic acid ester, Ion quest-801, was studied. Batch experiments were carried out to investigate the effect of contact time, V/M ratio, extractant concentration, nitric acid molarity, lanthanide concentration and temperature. The data obtained are discussed in terms of extraction equilibrium and separation factors between the lanthanides as well as certain sorption models. Possible use of column chromatography containing the developed extractant material was assessed

  19. Structural characterization of saturated branched chain fatty acid methyl esters by collisional dissociation of molecular ions generated by electron ionization.

    Science.gov (United States)

    Ran-Ressler, Rinat R; Lawrence, Peter; Brenna, J Thomas

    2012-01-01

    Saturated branched chain fatty acids (BCFA) are present as complex mixtures in numerous biological samples. The traditional method for structure elucidation, electron ionization (EI) mass spectrometry, sometimes does not unambiguously enable assignment of branching in isomeric BCFA. Zirrolli and Murphy (Zirrolli , J. A. , and R. A. Murphy. 1993. Low-energy tandem mass spectrometry of the molecular ion derived from fatty acid methyl esters: a novel method for analysis of branched-chain fatty acids. J. Am. Soc. Mass Spectrom. 4: 223-229.) showed that the molecular ions of four BCFA methyl ester (BCFAME) yield highly characteristic fragments upon collisional dissociation using a triple quadrupole instrument. Here, we confirm and extend these results by analysis using a tabletop 3-D ion trap for activated molecular ion EI-MS/MS to 30 BCFAME. iso-BCFAME produces a prominent ion (30-100% of base peak) for [M-43] (M-C₃H₇), corresponding to the terminal isopropyl moiety in the original iso-BCFAME. Anteiso-FAME yield prominent ions (20-100% of base peak) corresponding to losses on both side of the methyl branch, [M-29] and [M-57], and tend to produce more prominent m/z 115 peaks corresponding to a cyclization product around the ester. Dimethyl and tetramethyl FAME, with branches separated by at least one methylene group, yield fragment on both sides of the sites of methyl branches that are more than 6 C away from the carboxyl carbon. EI-MS/MS yields uniquely specific ions that enable highly confident structural identification and quantification of BCFAME.

  20. Lattice doped Zn–SnO{sub 2} nanospheres: A systematic exploration of dopant ion effects on structural, optical, and enhanced gas sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Baraneedharan, P. [Nanoscience and Technology, Anna University – BIT Campus, Tiruchirappalli 620024 (India); Alternative Energy and Nanotechnology Laboratory, Indian Institute of Technology Madras, Chennai 600036 (India); Imran Hussain, S. [Nanoscience and Technology, Anna University – BIT Campus, Tiruchirappalli 620024 (India); Department of Applied Science and Technology, Anna University, Chennai 600 025 (India); Dinesh, V.P. [Nanosensor Laboratory, PSG Institute of Advanced Studies, Coimbatore 641004 (India); Siva, C. [Nanoscience and Technology, Anna University – BIT Campus, Tiruchirappalli 620024 (India); Department of Physics and Nanotechnology, SRM University, Kattankulathur 603 203 (India); Biji, P. [Nanosensor Laboratory, PSG Institute of Advanced Studies, Coimbatore 641004 (India); Sivakumar, M., E-mail: muthusiva@gmail.com [Nanoscience and Technology, Anna University – BIT Campus, Tiruchirappalli 620024 (India)

    2015-12-01

    Graphical abstract: - Highlights: • A simple, novel and surfactant free hydrothermal route to prepare SnO{sub 2} nanospheres. • A systematic investigation of growth mechanism with the assist of time dependent HR-TEM images. • Incorporation of Zn ions into SnO{sub 2} lattices clearly elucidated with XRD and XPS spectrums. • Three fold time increased response in Zn–SnO{sub 2} nanospheres when compared to undoped SnO{sub 2}. - Abstract: A surfactant-free one step hydrothermal method is reported to synthesize zinc (Zn{sup 2+}) doped SnO{sub 2} nanospheres. The structural analysis of X-ray diffraction confirms the tetragonal crystal system of the material with superior crystalline nature. The shift in diffraction peak, variation in lattice constant and disparity in particle size confirm the incorporation of Zn{sup 2+} ions to the Sn host lattices. The lattice doped structure, the disparity in morphology, size and shape by the addition of Zn{sup 2+} ions are evident from X-ray photoelectron spectroscopic and electron microscopic analysis. Significant changes in the absorption edge and the band gap with increased doping concentration were observed in UV–vis absorption spectral analysis. The formation of acceptor energy levels with the incorporation of Zn{sup 2+} ions has a significant effect on the electrical conductivity of SnO{sub 2} nanospheres. Comparative tests for gas sensors based on Zn doped SnO{sub 2} nanospheres and SnO{sub 2} nanospheres clearly show that the former exhibited excellent NO{sub 2} sensing performance. The responses of Zn{sup 2+} ions incorporated SnO{sub 2} nanospheres sensor were increased 3 fold at trace level NO{sub 2} gas concentrations ranging from 1 to 5 ppm. The excellent sensitivity, selectivity and fast response make the Zn{sup 2+} doped SnO{sub 2} nanospheres ideal for NO{sub 2} sensing.

  1. Glutathione regulation-based dual-functional upconversion sensing-platform for acetylcholinesterase activity and cadmium ions.

    Science.gov (United States)

    Fang, Aijin; Chen, Hongyu; Li, Haitao; Liu, Meiling; Zhang, Youyu; Yao, Shouzhuo

    2017-01-15

    A dual-functional platform for the sensing of acetylcholinesterase (AChE) activity and cadmium ions (Cd 2+ ) was developed based on the fluorescence resonance energy transfer (FRET) between NaYF 4 :Yb,Er upconversion nanoparticles (UCNPs) and gold nanoparticles (AuNPs) via glutathione regulation. The detection mechanism is based on the fact that AuNPs can quench the fluorescence of UCNPs. AChE catalyzes the hydrolysis of acetylthiocholine (ATC) into thiocholine which reacts with AuNPs by S-Au conjunction and results the aggregation of AuNPs and change in fluorescence of UCNPs. Therefore, the AChE activity can be detected through the changes of the color of solution and fluorescence recovery of UCNPs. However, the presence of glutathione (GSH) can protect AuNPs from aggregation and enlarge the inter-particle distance between AuNPs and UCNPs. When Cd 2+ is added into the stable mixture of AuNPs, GSH and AChE/ATC, Cd 2+ could interact with GSH to form a spherical shaped (GSH) 4 Cd complex, which decreases the free GSH on the surface of AuNPs to weaken the stability of AuNPs and lead to the easily aggregation of them in the system. The aggregated-AuNPs are released from the surface of UCNPs, which results in the fluorescence of UCNPs gradually recovered. Under the optimized conditions, the detection limits of AChE activity and Cd 2+ are estimated to be 0.015mU/mL and 0.2µM, respectively. The small molecules regulated dual-functional platform based on UCNPs/AuNPs is a simple, label-free method and can be applied for the turn-on fluorescence detection of AChE activity in human serum and Cd 2+ in real water samples. The present work demonstrates a general strategy for the design of small molecules regulated multifunctional platform and will be expanded for different areas in the future. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Sensing and adaptation to low pH mediated by inducible amino acid decarboxylases in Salmonella.

    Science.gov (United States)

    Viala, Julie P M; Méresse, Stéphane; Pocachard, Bérengère; Guilhon, Aude-Agnès; Aussel, Laurent; Barras, Frédéric

    2011-01-01

    During the course of infection, Salmonella enterica serovar Typhimurium must successively survive the harsh acid stress of the stomach and multiply into a mild acidic compartment within macrophages. Inducible amino acid decarboxylases are known to promote adaptation to acidic environments. Three low pH inducible amino acid decarboxylases were annotated in the genome of S. Typhimurium, AdiA, CadA and SpeF, which are specific for arginine, lysine and ornithine, respectively. In this study, we characterized and compared the contributions of those enzymes in response to acidic challenges. Individual mutants as well as a strain deleted for the three genes were tested for their ability (i) to survive an extreme acid shock, (ii) to grow at mild acidic pH and (iii) to infect the mouse animal model. We showed that the lysine decarboxylase CadA had the broadest range of activity since it both had the capacity to promote survival at pH 2.3 and growth at pH 4.5. The arginine decarboxylase AdiA was the most performant in protecting S. Typhimurium from a shock at pH 2.3 and the ornithine decarboxylase SpeF conferred the best growth advantage under anaerobiosis conditions at pH 4.5. We developed a GFP-based gene reporter to monitor the pH of the environment as perceived by S. Typhimurium. Results showed that activities of the lysine and ornithine decarboxylases at mild acidic pH did modify the local surrounding of S. Typhimurium both in culture medium and in macrophages. Finally, we tested the contribution of decarboxylases to virulence and found that these enzymes were dispensable for S. Typhimurium virulence during systemic infection. In the light of this result, we examined the genomes of Salmonella spp. normally responsible of systemic infection and observed that the genes encoding these enzymes were not well conserved, supporting the idea that these enzymes may be not required during systemic infection.

  3. Sensing and adaptation to low pH mediated by inducible amino acid decarboxylases in Salmonella.

    Directory of Open Access Journals (Sweden)

    Julie P M Viala

    Full Text Available During the course of infection, Salmonella enterica serovar Typhimurium must successively survive the harsh acid stress of the stomach and multiply into a mild acidic compartment within macrophages. Inducible amino acid decarboxylases are known to promote adaptation to acidic environments. Three low pH inducible amino acid decarboxylases were annotated in the genome of S. Typhimurium, AdiA, CadA and SpeF, which are specific for arginine, lysine and ornithine, respectively. In this study, we characterized and compared the contributions of those enzymes in response to acidic challenges. Individual mutants as well as a strain deleted for the three genes were tested for their ability (i to survive an extreme acid shock, (ii to grow at mild acidic pH and (iii to infect the mouse animal model. We showed that the lysine decarboxylase CadA had the broadest range of activity since it both had the capacity to promote survival at pH 2.3 and growth at pH 4.5. The arginine decarboxylase AdiA was the most performant in protecting S. Typhimurium from a shock at pH 2.3 and the ornithine decarboxylase SpeF conferred the best growth advantage under anaerobiosis conditions at pH 4.5. We developed a GFP-based gene reporter to monitor the pH of the environment as perceived by S. Typhimurium. Results showed that activities of the lysine and ornithine decarboxylases at mild acidic pH did modify the local surrounding of S. Typhimurium both in culture medium and in macrophages. Finally, we tested the contribution of decarboxylases to virulence and found that these enzymes were dispensable for S. Typhimurium virulence during systemic infection. In the light of this result, we examined the genomes of Salmonella spp. normally responsible of systemic infection and observed that the genes encoding these enzymes were not well conserved, supporting the idea that these enzymes may be not required during systemic infection.

  4. Eu(III)-functionalized MIL-124 as fluorescent probe for highly selectively sensing ions and organic small molecules especially for Fe(III) and Fe(II).

    Science.gov (United States)

    Xu, Xiao-Yu; Yan, Bing

    2015-01-14

    A layerlike MOF (MIL-124, orGa2(OH)4(C9O6H4)) has been prepared and chosen as a parent compound to encapsulate Eu(3+) cations by one uncoordinated carbonyl group in its pores. The Eu(3+)-incorporated sample (Eu(3+)@MIL-124) is fully characterized, which shows excellent luminescence and good fluorescence stability in water or other organic solvents. Subsequently, we choose Eu(3+)@MIL-124 as sensitive probe for sensing metal ions, anions, and organic small molecules because of its robust framework. Studying of the luminescence properties reveals that the complex Eu(3+)@MIL-124 was developed as a highly selective and sensitive probe for detection of Fe(3+) (detection limit, 0.28 μM) and Fe(2+) ions through fluorescence quenching of Eu(3+) and MOF over other metal ions. In connection to this, a probable sensing mechanism was also discussed in this paper. In addition, when Eu(3+)@MIL-124 was immersed in the different anions solutions and organic solvents, it also shows highly selective for Cr2O7(2-)(detection limit, 0.15 μM)and acetone. Remarkably, it is the first Eu-doped MOF to exhibit an excellent ability for the detection of Fe(3+) and Fe(2+) in an aqueous environment without any structural disintegration of the framework.

  5. Novel (Phenylethynyl)pyrene-LNA Constructs for Fluorescence SNP Sensing in Polymorphic Nucleic Acid Targets

    DEFF Research Database (Denmark)

    Astakhova, Irina Kira; Samokhina, Evgeniya; Babu, B Ravindra

    2012-01-01

    We describe fluorescent oligonucleotide probes labeled with novel (phenylethynyl)pyrene dyes attached to locked nucleic acids. Furthermore, we prove the utility of these probes for the effective detection of single-nucleotide polymorphisms in natural nucleic acids. High-affinity hybridization......DNA and RNA gene fragments. Target sequences were obtained by analysis of 200 clinical samples from patients currently receiving anti-HIV/AIDS combination therapy at the Russian Federal AIDS Center. Using these fluorescent oligonucleotides, we were able to detect the target mutation despite all the challenges...

  6. Rapid Screening of Carboxylic Acids from Waste and Surface Waters by ESI-MS/MS Using Barium Ion Chemistry and On-Line Membrane Sampling

    Science.gov (United States)

    Duncan, Kyle D.; Volmer, Dietrich A.; Gill, Chris G.; Krogh, Erik T.

    2016-03-01

    Negative ion tandem mass spectrometric analysis of aliphatic carboxylic acids often yields only non-diagnostic ([M - H]-) ions with limited selective fragmentation. However, carboxylates cationized with Ba2+ have demonstrated efficient dissociation in positive ion mode, providing structurally diagnostic product ions. We report the application of barium adducts followed by collision induced dissociation (CID), to improve selectivity for rapid screening of carboxylic acids in complex aqueous samples. The quantitative MS/MS method presented utilizes common product ions of [M - H + Ba]+ precursor ions. The mechanism of product ion formation is investigated using isotopically labeled standards and a series of structurally related carboxylic acids. The results suggest that hydrogen atoms in the β and γ positions yield common product ions ([BaH]+ and [BaOH]+). Furthermore, the diagnostic product ion at m/z 196 serves as a qualifying ion for carboxylate species. This methodology has been successfully used in conjunction with condensed phase membrane introduction mass spectrometry (CP-MIMS), with barium acetate added directly to the methanol acceptor phase. The combination enables rapid screening of carboxylic acids directly from acidified water samples (wastewater effluent, spiked natural waters) using a capillary hollow fiber PDMS membrane immersion probe. We have applied this technique for the direct analysis of complex naphthenic acid mixtures spiked into natural surface waters using CP-MIMS. Selectivity at the ionization and tandem mass spectrometry level eliminate isobaric interferences from hydroxylated species present within the samples, which have been observed in negative electrospray ionization.

  7. Rapid Screening of Carboxylic Acids from Waste and Surface Waters by ESI-MS/MS Using Barium Ion Chemistry and On-Line Membrane Sampling.

    Science.gov (United States)

    Duncan, Kyle D; Volmer, Dietrich A; Gill, Chris G; Krogh, Erik T

    2016-03-01

    Negative ion tandem mass spectrometric analysis of aliphatic carboxylic acids often yields only non-diagnostic ([M - H](-)) ions with limited selective fragmentation. However, carboxylates cationized with Ba(2+) have demonstrated efficient dissociation in positive ion mode, providing structurally diagnostic product ions. We report the application of barium adducts followed by collision induced dissociation (CID), to improve selectivity for rapid screening of carboxylic acids in complex aqueous samples. The quantitative MS/MS method presented utilizes common product ions of [M - H + Ba](+) precursor ions. The mechanism of product ion formation is investigated using isotopically labeled standards and a series of structurally related carboxylic acids. The results suggest that hydrogen atoms in the β and γ positions yield common product ions ([BaH](+) and [BaOH](+)). Furthermore, the diagnostic product ion at m/z 196 serves as a qualifying ion for carboxylate species. This methodology has been successfully used in conjunction with condensed phase membrane introduction mass spectrometry (CP-MIMS), with barium acetate added directly to the methanol acceptor phase. The combination enables rapid screening of carboxylic acids directly from acidified water samples (wastewater effluent, spiked natural waters) using a capillary hollow fiber PDMS membrane immersion probe. We have applied this technique for the direct analysis of complex naphthenic acid mixtures spiked into natural surface waters using CP-MIMS. Selectivity at the ionization and tandem mass spectrometry level eliminate isobaric interferences from hydroxylated species present within the samples, which have been observed in negative electrospray ionization.

  8. Ratiometric, visual, dual-signal fluorescent sensing and imaging of pH/copper ions in real samples based on carbon dots-fluorescein isothiocyanate composites.

    Science.gov (United States)

    Zhu, Xinxin; Jin, Hui; Gao, Cuili; Gui, Rijun; Wang, Zonghua

    2017-01-01

    In this article, a facile aqueous synthesis of carbon dots (CDs) was developed by using natural kelp as a new carbon source. Through hydrothermal carbonization of kelp juice, fluorescent CDs were prepared and the CDs' surface was modified with polyethylenimine (PEI). The PEI-modified CDs were conjugated with fluorescein isothiocyanate (FITC) to fabricate CDs-FITC composites. To exploit broad applications, the CDs-FITC composites were developed as fluorescent sensing or imaging platforms of pH and Cu 2+ . Analytical performances of the composites-based fluorescence (FL) sensors were evaluated, including visual FL imaging of pH in glass bottle, ratiometric FL sensing of pH in yogurt samples, visual FL latent fingerprint and leaf imaging detection of [Cu 2+ ], dual-signal FL sensing of [Cu 2+ ] in yogurt and human serum samples. Experimental results from ratiometric, visual, dual-signal FL sensing and imaging applications confirmed the high feasibility, accuracy, stabilization and simplicity of CDs-FITC composites-based FL sensors for the detection of pH and Cu 2+ ions in real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Anion sensing with a Lewis acidic BODIPY-antimony(v) derivative.

    Science.gov (United States)

    Christianson, Anna M; Gabbaï, François P

    2017-02-21

    We describe the synthesis of a BODIPY dye substituted with a Lewis acidic antimony(v) moiety. This compound, which has been fully characterized, shows a high affinity for small anions including fluoride and cyanide, the complexation of which elicits a fluorescence turn-on response.

  10. Use of a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin column and propionic acid as an eluent in ion-exclusion/adsorption chromatography of aliphatic carboxylic acids and ethanol in food samples.

    Science.gov (United States)

    Mori, Masanobu; Hironaga, Takahiro; Kajiwara, Hiroe; Nakatani, Nobutake; Kozaki, Daisuke; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2011-01-01

    We developed an ion-exclusion/adsorption chromatography (IEAC) method employing a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin (PS-WCX) column with propionic acid as the eluent for the simultaneous determination of multivalent aliphatic carboxylic acids and ethanol in food samples. The PS-WCX column well resolved mono-, di-, and trivalent carboxylic acids in the acidic eluent. Propionic acid as the eluent gave a higher signal-to-noise ratio, and enabled sensitive conductimetric detection of analyte acids. We found the optimal separation condition to be the combination of a PS-WCX column and 20-mM propionic acid. Practical applicability of the developed method was confirmed by using a short precolumn with a strongly acidic cation-exchange resin in the H(+)-form connected before the separation column; this was to remove cations from food samples by converting them to hydrogen ions. Consequently, common carboxylic acids and ethanol in beer, wine, and soy sauce were successfully separated by the developed method.

  11. Application of Carbon-Microsphere-Modified Electrodes for Electrochemistry of Hemoglobin and Electrocatalytic Sensing of Trichloroacetic Acid

    Science.gov (United States)

    Wang, Wen-Cheng; Yan, Li-Jun; Shi, Fan; Niu, Xue-Liang; Huang, Guo-Lei; Zheng, Cai-Juan; Sun, Wei

    2015-01-01

    By using the hydrothermal method, carbon microspheres (CMS) were fabricated and used for electrode modification. The characteristics of CMS were investigated using various techniques. The biocompatible sensing platform was built by immobilizing hemoglobin (Hb) on the micrometer-sized CMS-modified electrode with a layer of chitosan membrane. On the cyclic voltammogram, a couple of quasi-reversible cathodic and anodic peaks appeared, showing that direct electrochemistry of Hb with the working electrode was achieved. The catalytic reduction peak currents of the bioelectrode to trichloroacetic acid was established in the linear range of 2.0~70.0 mmol·L−1 accompanied by a detection limit of 0.30 mmol·L−1 (3σ). The modified electrode displayed favorable sensitivity, good reproducibility and stability, which suggests that CMS is promising for fabricating third-generation bioelectrochemical sensors. PMID:26703621

  12. Potential of ethylenediaminedi(o-hydroxyphenylacetic acid) and N,N'-bis(hydroxybenzyl)ethylenediamine-N,N'-diacetic acid for the determination of metal ions by capillary electrophoresis.

    Science.gov (United States)

    Krokhin, O V; Kuzina, O V; Hoshino, H; Shpigun, O A; Yotsuyanagi, T

    2000-08-25

    Two aromatic polyaminocarboxylate ligands, ethylenediaminedi(o-hydroxyphenylacetic acid) (EDDHA) and N,N'-bis(hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED), were applied for the separation of transition and heavy metal ions by the ion-exchange variant of electrokinetic chromatography. EDDHA structure contains two chiral carbon centers. It makes it impossible to use the commercially available ligand. All the studied metal ions showed two peaks, which correspond to meso and rac forms of the ligand. The separation of metal-HBED chelates was performed using poly(diallyldimethylammonium) polycations in mixed acetate-hydroxide form. Simultaneous separation of nine single- and nine double-charged HBED chelates, including In(III), Ga(III), Co(II)-(III) and Mn(II)-(III) pairs demonstrated the efficiency of 40,000-400,000 theoretical plates. The separation of Co(III), Fe(III) complexes with different arrangements of donor groups and oxidation of Co(II), Mn(H), Fe(II) ions in reaction with HBED have been discussed.

  13. The Mechanism of Redox Reaction between Palladium(II Complex Ions and Potassium Formate in Acidic Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Wojnicki M.

    2017-06-01

    Full Text Available The kinetics studies of redox reaction between palladium(II chloride complex ions and potassium formate in acidic aqueous solutions was investigated. It was shown, that the reduction reaction of Pd(II is selective in respect to Pd(II complex structure. The kinetic of the process was monitored spectrophotometrically. The influence of chloride ions concentration, Pd(II initial concentration, reductant concentration, ionic strength as well as the temperature were investigated in respect to the process dynamics. Arrhenius equation parameters were determined and are equal to 65.8 kJ/mol, and A = 1.12×1011 s−1.

  14. Effect of organic acids produced by penicillium notatum on the extraction of metals ions from brown shale

    International Nuclear Information System (INIS)

    Bhatti, H.N.; Sarwar, S.; Ilyas, S.

    2012-01-01

    Preset study was undertaken to check the bio leaching feasibility of brown shale with Penicillium notatum by using different carbon sources. Large quantities of the metal ions are embodied in shales that can be recovered. Presently available techniques (pyrometallurgical and hydrometallurgical) are expensive or may have a negative impact on the environment. Penicillium notatum exhibited a good potential in generating varieties of organic acids effective for metal ions solubilization. Maximum leaching of Cu (91.55 %) and Mg (79.83 %) was obtained with glucose as substrate while maximum recovery of Mn (71.46 %) was obtained in medium having molasses as substrate. (author)

  15. STABILITY OF BETACYANIN PIGMENTS FROM RED PURPLE PITAYA FRUIT (Hylocereus polyrhizus : INFLUENCE OF PH, TEMPERATURE, METAL IONS AND ASCORBIC ACID

    Directory of Open Access Journals (Sweden)

    Tang, C.S Tang, C.S

    2010-06-01

    Full Text Available Betacyanin pigments from red-purple pitaya fruit (Hylocereus polyrhizus could be an attractive source of red colourant for food application. This paper presents results on the extraction of betacyanin pigments from pitaya fruits grown locally in Malaysia. Both the flesh of the fruit and its mesocarp were investigated and it was found that the flesh had higher pigment contents compared to its peel component. The concentration of betacyanins expressed as betanin equivalents per 100 g of flesh and peel were 10.1 ± 0.6 mg and 6.7 ± 0.2 mg, respectively when 80% methanol was used.  The stability of betacyanin pigments were investigated at different pH, temperature and in presence of different concentrations of metal ions (Cu2+ and Fe2+ and ascorbic acid. The results showed that the pigment was most stable at pH range between 5 and 6. However, it forfeited its stability to the heat induced at elevated temperatures. Metal ions (Cu2+ and Fe2+ proved to be capable of accelerating betacyanin degradation, with Cu2+ exhibiting the greatest effect. By contrast, supplementation with ascorbic acid could enhance the pigment stability against the detrimental effects caused by pH, temperature and metal ions. Nevertheless, if the concentration of ascorbic acid exceeds 0.7 %, it may change its role from pigment stabilizer to become a pro-oxidant.    Keywords: Betacyanin, pigments, pitaya fruit, Hylocereus polyrhizus, ascorbic acid

  16. An azine based sensor for selective detection of Cu2 + ions and its copper complex for sensing of phosphate ions in physiological conditions and in living cells

    Science.gov (United States)

    Tiwari, Karishma; Kumar, Sumit; Kumar, Vipan; Kaur, Jeevanjot; Arora, Saroj; Mahajan, Rakesh Kumar

    2018-02-01

    A simple and cost effective unsymmetrical azine based Schiff base, 5-diethylamino-2-[(2-hydroxy-benzylidene)hydrazonomethyl]-phenol (1) was synthesized which selectively detect Cu2 + ions in the presence of other competitive ions through ;naked eye; in physiological conditions (EtOH-buffer (1:1, v/v, HEPES 10 mM, pH = 7.4)). The presence of Cu2 + induce color change from light yellow green to yellow with the appearance of a new band at 450 nm in UV-Vis spectra of Schiff base 1. The fluorescence of Schiff base 1 (10 μM) was quenched completely in the presence of 2.7 equiv. of Cu2 + ions. Sub-micromolar limit of detection (LOD = 3.4 × 10- 7 M), efficient Stern-Volmer quenching constant (KSV = 1.8 × 105 L mol- 1) and strong binding constant (log Kb = 5.92) has been determined with the help of fluorescence titration profile. Further, 1 - Cu2 + complex was employed for the detection of phosphate ions (PO43 -, HPO42 - and H2PO4-) at micromolar concentrations in EtOH-buffer of pH 7.4 based on fluorescence recovery due to the binding of Cu2 + with phosphate ions. Solubility at low concentration in aqueous medium, longer excitation (406 nm) and emission wavelength (537 nm), and biocompatibility of Schiff base 1 formulates its use in live cell imaging.

  17. Thermal behaviour of nicotinic acid, sodium nicotinate and its compounds with some bivalent transition metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, A.L.C.S. do; Caires, F.J., E-mail: caires.flavio@yahoo.com.br; Gomes, D.J.C.; Gigante, A.C.; Ionashiro, M.

    2014-01-10

    Graphical abstract: - Highlights: • The transition metal ion nicotinates were synthesized. • The TG–DTA curves provided previously unreported information about thermal behaviour. • The gaseous products released were detected by TG–DSC coupled to FTIR. - Abstract: Solid-state M(L){sub 2}·nH{sub 2}O compounds, where M stands for bivalent transition metals (Mn, Fe, Co, Ni, Cu and Zn), L is nicotinate and n = 0–4.5, have been synthesized. Characterization and thermal behaviour of these compounds were investigated employing elemental analysis based on the mass losses observed in the TG–DTA curves, complexometry, X-ray diffractometry, infrared spectroscopy (FTIR), simultaneous thermogravimetric and differential thermal analysis (TG–DTA) and TG–DSC coupled to FTIR. The thermal behaviour of nicotinic acid and its sodium salt was also investigated. For the hydrated transition metal compounds, the dehydration and thermal decomposition of the anhydrous compounds occur in a single step. For the sodium nicotinate, the final residue up to 765 °C is sodium carbonate and for the transition metal nicotinates, the final residues are Mn{sub 3}O{sub 4}, Fe{sub 2}O{sub 3}, Co{sub 3}O{sub 4}, NiO, CuO and ZnO. The results also provided information concerning the thermal stability, thermal decomposition and identification of the gaseous products evolved during the thermal decomposition of the compounds.

  18. Ion-exchange equilibrium of N-acetyl-D-neuraminic acid on a strong anionic exchanger.

    Science.gov (United States)

    Wu, Jinglan; Ke, Xu; Zhang, Xudong; Zhuang, Wei; Zhou, Jingwei; Ying, Hanjie

    2015-09-15

    N-acetyl-D-neuraminic acid (Neu5Ac) is a high value-added product widely applied in the food industry. A suitable equilibrium model is required for purification of Neu5Ac based on ion-exchange chromatography. Hence, the equilibrium uptake of Neu5Ac on a strong anion exchanger, AD-1 was investigated experimentally and theoretically. The uptake of Neu5Ac by the hydroxyl form of the resin occurred primarily by a stoichiometric exchange of Neu5Ac(-) and OH(-). The experimental data showed that the selectivity coefficient for the exchange of Neu5Ac(-) with OH(-) was a non-constant quantity. Subsequently, the Saunders' model, which took into account the dissociation reactions of Neu5Ac and the condition of electroneutrality, was used to correlate the Neu5Ac sorption isotherms at various solution pHs and Neu5Ac concentrations. The model provided an excellent fit to the binary exchange data for Cl(-)/OH(-) and Neu5Ac(-)/OH(-), and an approximate prediction of equilibrium in the ternary system Cl(-)/Neu5Ac(-)/OH(-). This basic information combined with the general mass transfer model could lay the foundation for the prediction of dynamic behavior of fixed bed separation process afterwards. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Effect of Pb2+ ions on ilmenite flotation and adsorption of benzohydroxamic acid as a collector

    Science.gov (United States)

    Xu, Longhua; Tian, Jia; Wu, Houqin; Lu, Zhongyuan; Yang, Yaohui; Sun, Wei; Hu, Yuehua

    2017-12-01

    The effects of Pb2+ ions on ilmenite flotation and adsorption of benzohydroxamic acid (BHA) as a collector were investigated using microflotation tests, zeta potential measurements, adsorption analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The microflotation results indicate that the addition of Pb2+ significantly improves the recovery of ilmenite using BHA as a collector. A maximum recovery of 88.46% is obtained at pH 8.12 in the presence of Pb2+; a maximum recovery of 45% is obtained at the same pH using BHA alone. At pHs below 8.0, lead nitrate are mainly present in the solution as Pb2+ and PbOH+, while at pHs above 8.0, the predominant components are Pb(OH)2(s) and Pb(OH)3-. The adsorption of these lead species influences the zeta potential of ilmenite and the number of activated sites on the ilmenite surface. FTIR and XPS analyses reveal that lead species and BHA react with the metal sites on the ilmenite surface. The lead species in solution are either adsorbed onto the ilmenite surface, which increases the surface activity of ilmenite, or react with BHA in solution to form complexes of lead and BHA.

  20. Fractionation of equine antivenom using caprylic acid precipitation in combination with cationic ion-exchange chromatography.

    Science.gov (United States)

    Raweerith, Rutai; Ratanabanangkoon, Kavi

    2003-11-01

    A combined process of caprylic acid (CA) precipitation and ion-exchange chromatography on SP-Sepharose was studied as a means to fractionate pepsin-digested horse antivenom F(ab')(2) antibody. In the CA precipitation, the optimal concentration for fractionation of F(ab')(2) from pepsin-digested horse plasma was 2%, in which 89.61% of F(ab')(2) antibody activity was recovered in the supernatant with 1.5-fold purification. A significant amount of pepsin was not precipitated and remained active under these conditions. An analytical cation exchanger Protein-Pak SP 8HR HPLC column was tested to establish optimal conditions for the effective separation of IgG, albumin, pepsin and CA from the F(ab')(2) product. From these results, the supernatant from CA precipitation of pepsin-digested plasma was subjected to a SP-Sepharose column chromatography using a linear salt gradient. With stepwise elution, a peak containing F(ab')(2) antibody could be obtained by elution with 0.25 M NaCl. The total recovery of antibody was 65.56% with 2.91-fold purification, which was higher than that achieved by ammonium sulfate precipitation. This process simultaneously and effectively removed residual pepsin, high molecular weight aggregates and CA in the final F(ab')(2) product, and should be suitable for large-scale fractionation of therapeutic equine antivenoms.

  1. Thermal behaviour of nicotinic acid, sodium nicotinate and its compounds with some bivalent transition metal ions

    International Nuclear Information System (INIS)

    Nascimento, A.L.C.S. do; Caires, F.J.; Gomes, D.J.C.; Gigante, A.C.; Ionashiro, M.

    2014-01-01

    Graphical abstract: - Highlights: • The transition metal ion nicotinates were synthesized. • The TG–DTA curves provided previously unreported information about thermal behaviour. • The gaseous products released were detected by TG–DSC coupled to FTIR. - Abstract: Solid-state M(L) 2 ·nH 2 O compounds, where M stands for bivalent transition metals (Mn, Fe, Co, Ni, Cu and Zn), L is nicotinate and n = 0–4.5, have been synthesized. Characterization and thermal behaviour of these compounds were investigated employing elemental analysis based on the mass losses observed in the TG–DTA curves, complexometry, X-ray diffractometry, infrared spectroscopy (FTIR), simultaneous thermogravimetric and differential thermal analysis (TG–DTA) and TG–DSC coupled to FTIR. The thermal behaviour of nicotinic acid and its sodium salt was also investigated. For the hydrated transition metal compounds, the dehydration and thermal decomposition of the anhydrous compounds occur in a single step. For the sodium nicotinate, the final residue up to 765 °C is sodium carbonate and for the transition metal nicotinates, the final residues are Mn 3 O 4 , Fe 2 O 3 , Co 3 O 4 , NiO, CuO and ZnO. The results also provided information concerning the thermal stability, thermal decomposition and identification of the gaseous products evolved during the thermal decomposition of the compounds

  2. An accurate cost effective DFT approach to study the sensing behaviour of polypyrrole towards nitrate ions in gas and aqueous phases.

    Science.gov (United States)

    Wasim, Fatima; Mahmood, Tariq; Ayub, Khurshid

    2016-07-28

    Density functional theory (DFT) calculations have been performed to study the response of polypyrrole towards nitrate ions in gas and aqueous phases. First, an accurate estimate of interaction energies is obtained by methods calibrated against the gold standard CCSD(T) method. Then, a number of low cost DFT methods are also evaluated for their ability to accurately estimate the binding energies of polymer-nitrate complexes. The low cost methods evaluated here include dispersion corrected potential (DCP), Grimme's D3 correction, counterpoise correction of the B3LYP method, and Minnesota functionals (M05-2X). The interaction energies calculated using the counterpoise (CP) correction and DCP methods at the B3LYP level are in better agreement with the interaction energies calculated using the calibrated methods. The interaction energies of an infinite polymer (polypyrrole) with nitrate ions are calculated by a variety of low cost methods in order to find the associated errors. The electronic and spectroscopic properties of polypyrrole oligomers nPy (where n = 1-9) and nPy-NO3(-) complexes are calculated, and then extrapolated for an infinite polymer through a second degree polynomial fit. Charge analysis, frontier molecular orbital (FMO) analysis and density of state studies also reveal the sensing ability of polypyrrole towards nitrate ions. Interaction energies, charge analysis and density of states analyses illustrate that the response of polypyrrole towards nitrate ions is considerably reduced in the aqueous medium (compared to the gas phase).

  3. Photophysical property of rhodamine-cored poly(amidoamine) dendrimers: Simultaneous effect of spirolactam ring-opening and PET process on sensing trivalent chromium ion

    International Nuclear Information System (INIS)

    Lei Yonglin; Su Yuanqiang; Huo Jichuan

    2011-01-01

    Two novel poly(amidoamine) (PAMAM) dendrimers, comprising rhodamine B unit in the core and 1-phenyl-3-methyl-5-pyrazolone unit at the periphery, have been synthesized and characterized. Both dendrimers displayed high selectivity and sensitivity towards Cr 3+ ion. As considering the potential of being applied as fluorescent sensors for Cr 3+ ion, we studied the complexes formed between the dendrimers and Cr 3+ ion. Different PAMAM dendrimers had different recognition mechanism towards Cr 3+ ion. For dendrimer G2, the recognition of Cr 3+ was mainly due to the ring-opening of spirolactam. However, it significantly depended on the simultaneous effect of ring-opening of spirolactam and photoinduced electron transfer (PET) in the case of dendrimer G3. - Highlights: → First synthesize two novel PAMAM simultaneously containing rhodamine and pyrazolone. → Novel dendrimer show high selectivity and sensitivity towards Cr 3+ . → Recognition Cr 3+ of dendrimer G2 is dominantly due to the ring-opening mechanism. → Sensing Cr 3+ of dendrimer G3 is dependent on simultaneous mechanisms of ring-opening and PET.

  4. Effects of n-3 polyunsaturated fatty acids on cardiac ion channels

    Directory of Open Access Journals (Sweden)

    Cristina eMoreno

    2012-07-01

    Full Text Available Dietary n-3 polyunsaturated fatty acids (PUFAs have been reported to exhibit antiarrhythmic properties, attributed to their capability to modulate ion channels. In the present review, we will focus on the effects of PUFAs on cardiac sodium channel (Nav1.5 and two potassium channels (Kv (Kv1.5 and Kv11.1. n-3 marine (docohexaenoic and eicohexapentaenoic acid and plant origin (alpha-linolenic acid PUFAs block Kv1.5 and Kv11.1 channels at physiological concentrations. Also, DHA and EPA decreased Nav1.5 and calcium channels. These effects on Na and Ca channels theoretically should shorten the cardiac APD, whereas the blocking actions of n-3 PUFAs of Kv channels should lengthen the cardiac action potential. Experiments performed in female rabbits fed with a diet rich in n-3 PUFAs show a longer cardiac action potential and effective refractory period. This study was performed to analyze if their antiarrhythmic effects are due to a reduction of triangulation, reverse use-dependence, instability and dispersion of the cardiac action potential (TRIaD as a measure of proarrhythmic effects. Dietary n-3 PUFAs supplementation markedly reduced dofetilide-induced TRIaD and abolished dofetilide-induced torsades de pointes (TdP. Ultrafast sodium channel block by DHA may account for the antiarrhythmic protection of dietary supplements of n-3 PUFAs against dofetilide induced proarrhythmia observed in this animal model. The cardiac effects of n-3 PUFAs resemble those of amiodarone: both block sodium, calcium and potassium channels, have anti-adrenergic properties, can prolong the cardiac action potential, reverse TRIaD and suppress TdP. The main difference is that sodium channel block by n-3 PUFAs has a much faster onset and offset kinetics. Therefore, the electrophysiological profile of n-3 PUFAs appears more desirable: the duration of reduced sodium current (facilitates re-entry is much shorter. The n-3 PUFAs appear as a safer alternative to other antiarrhythmic

  5. Divalent metal ion removal from aqueous solution by acid-treated ...

    African Journals Online (AJOL)

    ions determined from the Langmuir isotherm showed that C. indica had the largest sorption capacity for Pb2+ ions and the least sorption for Ni2+. The results also showed that garlic-treatment of C. indica biomass enhanced its sorption capacity for the divalent metal ions, with the enhancement factor varying from 1.22 to 1.44 ...

  6. Na+,K+-ATPase amino acids involved in transport of the 3rd sodium ion

    DEFF Research Database (Denmark)

    Holm, Rikke; Einholm, Anja P.; Toustrup-Jensen, Mads Schak

    Available evidence indicates that two of the three Na+ ions bound in the E1 form occupy approximately the same positions as the K+ ions in E2, but the location of the third Na+ ion is unsolved. We have previously found a marked decrease in Na+ affinity for activation of phosphorylation in the hum...

  7. Lead-acid and lithium-ion batteries for the Chinese electric bike market and implications on future technology advancement

    International Nuclear Information System (INIS)

    Weinert, Jonathan X.; Burke, Andrew F.; Wei, Xuezhe

    2007-01-01

    China has been experiencing a rapid increase in battery-powered personal transportation since the late 1990s due to the strong growth of the electric bike and scooter (i.e. e-bike) market. Annual sales in China reached 17 million bikes year -1 in 2006. E-bike growth has been in part due to improvements in rechargeable valve-regulated lead-acid (VRLA) battery technology, the primary battery type for e-bikes. Further improvements in technology and a transition from VRLA to lithium-ion (Li-ion) batteries will impact the future market growth of this transportation mode in China and abroad. Battery performance and cost for these two types are compared to assess the feasibility of a shift from VRLA to Li-ion battery e-bikes. The requirements for batteries used in e-bikes are assessed. A widespread shift from VRLA to Li-ion batteries seems improbable in the near future for the mass market given the cost premium relative to the performance advantages of Li-ion batteries. As both battery technologies gain more real-world use in e-bike applications, both will improve. Cell variability is a key problematic area to be addressed with VRLA technology. For Li-ion technology, safety and cost are the key problem areas which are being addressed through the use of new cathode materials. (author)

  8. Potentiometric studies on ternary complexes involving some divalent transition metal ions, gallic acid and biologically abundant aliphatic dicarboxylic acids in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Abdelatty Mohamed Radalla

    2015-06-01

    Full Text Available Formation of binary and ternary complexes of the divalent transition metal ions, Cu2+, Ni2+, Co2+ and Zn2+ with gallic acid and the biologically important aliphatic dicarboxylic acids (adipic, succinic, malic, malonic, maleic, tartaric and oxalic acids were investigated by means of the potentiometric technique at 25 °C and I = 0.10 mol dm−3 NaNO3. The acid-base properties of the ligands were investigated and discussed. The acidity constants of gallic acid and aliphatic dicarboxylic acids were determined and used for determining the stability constants of the binary and ternary complexes formed in the aqueous medium under the above experimental conditions. The formation of the different 1:1 and 1:2 binary complexes and 1:1:1 ternary complexes are inferred from the corresponding potentiometric pH-metric titration curves. The ternary complex formation was found to occur in a stepwise manner. The stability constants of these binary and ternary systems were calculated. The values of Δ log K, percentage of relative stabilization (%R.S. and log X were evaluated and discussed. The concentration distribution of the various complex species formed in solution was evaluated and discussed. The mode of chelation of ternary complexes formed was ascertained by conductivity measurements.

  9. A general sensing strategy for detection of Fe{sup 3+} by using amino acid-modified graphene quantum dots as fluorescent probe

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Qi [College of Chemistry and Environmental Engineering, and Institute of Applied Chemistry, Shanxi Datong University, Datong, Shanxi, 037009 (China); Song, Jinping, E-mail: songjphxsxdt@163.com [College of Chemistry and Environmental Engineering, and Institute of Applied Chemistry, Shanxi Datong University, Datong, Shanxi, 037009 (China); Institute of Environmental Science, Shanxi University, Taiyuan, 030006 (China); Wang, Shangzhi; Yang, Jie; Guo, Yong [College of Chemistry and Environmental Engineering, and Institute of Applied Chemistry, Shanxi Datong University, Datong, Shanxi, 037009 (China); Dong, Chuan, E-mail: dc@sxu.edu.cn [Institute of Environmental Science, Shanxi University, Taiyuan, 030006 (China)

    2016-12-15

    Graphical abstract: Three kinds of amino acid-modified graphene quantum dots (GQDs) were synthesized through acylation and amination reactions. The as-synthesized GQDs can emit strong blue fluorescence. The presence of Fe{sup 3+} will cause obvious fluorescence quenching of the three kinds of GQDs. Based on these, a general sensing strategy for detection of Fe{sup 3+} was successfully developed. - Highlights: • Amino acid-modified graphene quantum dots (GQDs) were synthesized through acylation and amination reactions. • The presence of Fe{sup 3+} will cause obvious fluorescence quenching of the three kinds of GQDs. • A general sensing strategy for Fe{sup 3+} detection was successfully developed. • The proposed sensing strategy can successfully detect Fe{sup 3+} in real water sample. - Abstract: Amino acid-modified graphene quantum dots (GQDs) were synthesized through acylation and amination reactions. The as-synthesized GQDs were characterized by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and UV–vis absorption and fluorescence spectroscopy. A general sensing strategy for detection of Fe{sup 3+} was successfully developed. The detection limit can reach as low as 50 nM. Moreover, the proposed sensing system was successfully employed to detect Fe{sup 3+} in real water sample, and satisfactory results were obtained. This work will open up new avenues to develop potential applications of GQDs materials in environmental monitoring.

  10. Human gestation-associated tissues express functional cytosolic nucleic acid sensing pattern recognition receptors.

    Science.gov (United States)

    Bryant, A H; Menzies, G E; Scott, L M; Spencer-Harty, S; Davies, L B; Smith, R A; Jones, R H; Thornton, C A

    2017-07-01

    The role of viral infections in adverse pregnancy outcomes has gained interest in recent years. Innate immune pattern recognition receptors (PRRs) and their signalling pathways, that yield a cytokine output in response to pathogenic stimuli, have been postulated to link infection at the maternal-fetal interface and adverse pregnancy outcomes. The objective of this study was to investigate the expression and functional response of nucleic acid ligand responsive Toll-like receptors (TLR-3, -7, -8 and -9), and retinoic acid-inducible gene 1 (RIG-I)-like receptors [RIG-I, melanoma differentiation-associated protein 5 (MDA5) and Laboratory of Genetics and Physiology 2(LGP2)] in human term gestation-associated tissues (placenta, choriodecidua and amnion) using an explant model. Immunohistochemistry revealed that these PRRs were expressed by the term placenta, choriodecidua and amnion. A statistically significant increase in interleukin (IL)-6 and/or IL-8 production in response to specific agonists for TLR-3 (Poly(I:C); low and high molecular weight), TLR-7 (imiquimod), TLR-8 (ssRNA40) and RIG-I/MDA5 (Poly(I:C)LyoVec) was observed; there was no response to a TLR-9 (ODN21798) agonist. A hierarchical clustering approach was used to compare the response of each tissue type to the ligands studied and revealed that the placenta and choriodecidua generate a more similar IL-8 response, while the choriodecidua and amnion generate a more similar IL-6 response to nucleic acid ligands. These findings demonstrate that responsiveness via TLR-3, TLR-7, TLR-8 and RIG-1/MDA5 is a broad feature of human term gestation-associated tissues with differential responses by tissue that might underpin adverse obstetric outcomes. © 2017 British Society for Immunology.

  11. Improved sensitivity and selectivity of uric acid voltammetric sensing with mechanically grinded carbon/graphite electrodes

    Czech Academy of Sciences Publication Activity Database

    Hasoň, Stanislav; Vetterl, Vladimír; Jelen, František; Fojta, Miroslav

    2009-01-01

    Roč. 54, č. 6 (2009), s. 1864-1873 ISSN 0013-4686 R&D Projects: GA AV ČR(CZ) KAN200040651; GA ČR(CZ) GA203/07/1195; GA MŠk(CZ) LC06035; GA ČR(CZ) GA202/08/1688; GA AV ČR(CZ) IAA400040804 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : grinded carbon electrodes * voltammetry * uric acid Subject RIV: AQ - Safety, Health Protection, Human - Machine Impact factor: 3.325, year: 2009

  12. Liquid droplet sensing using twisted optical fiber couplers fabricated by hydrofluoric acid flow etching

    Science.gov (United States)

    Son, Gyeongho; Jung, Youngho; Yu, Kyoungsik

    2017-04-01

    We report a directional-coupler-based refractive index sensor and its cost-effective fabrication method using hydrofluoric acid droplet wet-etching and surface-tension-driven liquid flows. The proposed fiber sensor consists of a pair of twisted tapered optical fibers with low excess losses. The fiber cores in the etched microfiber region are exposed to the surrounding medium for efficient interaction with the guided light. We observe that the etching-based low-loss fiber-optic sensors can measure the water droplet volume by detecting the refractive index changes of the surrounding medium around the etched fiber core region.

  13. Method for characterization of low molecular weight organic acids in atmospheric aerosols using ion chromatography mass spectrometry.

    Science.gov (United States)

    Brent, Lacey C; Reiner, Jessica L; Dickerson, Russell R; Sander, Lane C

    2014-08-05

    The structural composition of PM2.5 monitored in the atmosphere is usually divided by the analysis of organic carbon, black (also called elemental) carbon, and inorganic salts. The characterization of the chemical composition of aerosols represents a significant challenge to analysts, and studies are frequently limited to determination of aerosol bulk properties. To better understand the potential health effects and combined interactions of components in aerosols, a variety of measurement techniques for individual analytes in PM2.5 need to be implemented. The method developed here for the measurement of organic acids achieves class separation of aliphatic monoacids, aliphatic diacids, aromatic acids, and polyacids. The selective ion monitoring capability of a triple quadropole mass analyzer was frequently capable of overcoming instances of incomplete separations. Standard Reference Material (SRM) 1649b Urban Dust was characterized; 34 organic acids were qualitatively identified, and 6 organic acids were quantified.

  14. Simultaneous determination of amino acids and carbohydrates in culture media of Clostridium thermocellum by valve-switching ion chromatography.

    Science.gov (United States)

    Fa, Yun; Yang, Haiyan; Ji, Chengshuai; Cui, He; Zhu, Xinshu; Du, Juan; Gao, Jun

    2013-10-10

    An improved method for the simultaneous determination of 20 amino acids and 7 carbohydrates using one-valve switching after injection, ion chromatography, and integrated pulsed amperometric detection is proposed. The resolution of the amino acids and carbohydrates in the cation trap column was investigated. In addition, parameters including flow liquid type, flow rate, concentration, and valve-switch timing were optimized. The method is time-saving, effective, and accurate for the simultaneous separation of amino acids and carbohydrates, with a mean correlation coefficient of >0.99 and repeatability of 0.5-4.6% for eight replicates. The method was successfully applied in the analysis of amino acids and carbohydrates in aseptic media and in extracellular culture media of three phenotypes of Clostridium thermocellum. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. The (non)sense of routinely analysing beta-hydroxybutyric acid in forensic toxicology casework.

    Science.gov (United States)

    Sadones, Nele; Lambert, Willy E; Stove, Christophe P

    2017-05-01

    Beta-hydroxybutyric acid (BHB) is a ketone body which is generated from fatty acids as an alternative energy source when glucose is not available. Determination of this compound may be relevant in the forensic laboratory as ketoacidosis - an elevated level of ketone bodies - may contribute to the cause of death. In this study, we aimed at determining the relevance of routinely implementing BHB analysis in the forensic toxicological laboratory, as BHB analysis typically requires an additional workload. We therefore performed an unbiased retrospective analysis of BHB in 599 cases, comprising 553 blood, 232 urine and 62 vitreous humour samples. Cases with BHB concentrations above 100mg/L (in blood, urine and/or vitreous humour) were invariably associated with elevated levels of acetone, another ketone body, the detection of which is already implemented in most forensic laboratories using the gas chromatographic procedure for ethanol quantification. Our retrospective analysis did not reveal any positive case that had been missed initially and confirms that BHB analysis can be limited to acetone positive cases. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Parallel Planar-Processed and Ion-Induced Electrically Isolated Future Generation AlGaN/GaN HEMT for Gas Sensing and Opto-Telecommunication Applications

    International Nuclear Information System (INIS)

    Ahmed, S; Bokhari, S H; Amin, F; Khan, L A; Hussain, Z

    2013-01-01

    Ion-implanted AlGaN/GaN High Electron Mobility Transistors (HEMT) devices were studied thoroughly to look into the possibilities of enhancing efficiency for high-power and high-frequency electronic and gas sensing applications. A dedicated experimental design was created in order to study the influence of the physical parameters in response to high energy (by virtue of in-situ beam heating due to highly energetic implantation) ion implantation to the active device regions in nitride HEMT structures. Disorder or damage created in the HEMT structure was then studied carefully with electrical characterization techniques such as Hall, I-V and G-V measurements. The evolution of the electrical characteristics affecting the high-power, high-frequency and ultra-high efficiency gas sensing operations were also analyzed by subjecting the HEMT active device regions to progressive time-temperature annealing cycles. Our suggested model can also provide a functional process engineering window to control the extent of 2D Electron mobility in AlGaN/GaN HEMT devices undergoing a full cycle of thermal impact (i.e. from a desirable conductive region to a highly compensated one)

  17. Speciation of selenoamino acids, selenonium ions and inorganic selenium by ion exchange HPLC with mass spectrometric detection and its application to yeast and algae

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt; Hansen, M.; Fan, T.

    2001-01-01

    Cation and anion exchange HPLC were used to separate a mixture of 12 selenium species comprising selenoamino acids, selenonium ions and inorganic selenium. The cationic species were separated from each other and from the co-injected anions using a cation exchange column with gradient elution...... by aqueous pyridinium formate at pH similar to 3 as the mobile phase. The anionic species were separated using an anion exchange column with isocratic elution by an aqueous salicylate-TRIS mobile phase at pH 8.5. The separated selenium species were detected as Se-80 by ICP-dynamic reaction cell (DRC...... acid extract of Chlorella algae contained dimethylselenonium propionate (DMSeP), which was verified by HPLC-ES-MS. Se-allylselenocysteine and selenoethionine was detected at the low ng g(-1) concentration level based on co-chromatography with the standard substances spiked to the algal extract....

  18. SEPARATION OF Fe (III, Cr(III, Cu(II, Ni(II, Co(II, AND Pb(II METAL IONS USING POLY(EUGENYL OXYACETIC ACID AS AN ION CARRIER BY A LIQUID MEMBRANE TRANSPORT METHOD

    Directory of Open Access Journals (Sweden)

    La Harimu

    2010-06-01

    Full Text Available Fe (III, Cr(III, Cu(II, Ni(II, Co(II, and Pb(II  metal ions had been separated using poly(eugenyl oxyacetic acid as an ion carrier by bulk liquid membrane transport method. The effect of pH, polyeugenyl oxyacetic acid ion carrier concentration, nitric acid concentration in the stripping solution, transport time, and metal concentration were optimized. The result showed that the optimum condition for transport of metal ions was at pH 4 for ion Fe(III and at pH 5 for Cr(III, Cu(II, Ni(II, Co(II, and Pb(II ions. The carrier volumes were optimum with concentration of 1 x 10-3 M at 7.5 mL for Cr(III, Cu (II,  Ni(II, Co(II ions and at 8.5 mL for Fe(III and Pb(II ions. The concentration of HNO3 in stripping phase was optimum at 2 M for Fe(III and Cu(II ions, 1 M for Cr(III, Ni(II and Co(II ions, and 0.5 M for Pb(II ion. The optimum transport times were 36 h for Fe(III and Co(II ions, and 48 h for Cr(III, Cu (II, Ni(II, and Pb(II ions. The concentration of metal ions accurately transported were 2.5 x 10-4 M for Fe(III and Cr(III ions, and 1 M for Cu (II, Ni(II, Co(II, and Pb(II ions. Compared to other metal ions the transport of Fe(III was the highest with selectivity order of Fe(III > Cr(III > Pb(II > Cu(II > Ni(II > Co(II. At optimum condition, Fe(III ion was transported through the membrane at 46.46%.   Keywords: poly(eugenyl oxyacetic acid, transport, liquid membrane, Fe (III, Cr(III, Cu(II, Ni(II, Co(II, and Pb(II ions

  19. Threshold photoelectron spectroscopy and photoionization total ion yield spectroscopy of simple organic acids, aldehydes, ketones and amines

    International Nuclear Information System (INIS)

    Yencha, Andrew J; Malins, Andrew E R; Siggel-King, Michele R F; Eypper, Marie; King, George C

    2009-01-01

    We have initiated a research program to investigate the ionization behavior of some simple organic molecules containing the carboxyl group (R 2 C=O), where R could be H, OH, NH 2 , or CH 3 or other aliphatic or aromatic carbon groups, using threshold photoelectron spectroscopy and photoionization total ion yield spectroscopy. We report here on the simplest organic acid, formic acid, and two simple aldehydes: acetaldehyde and the simplest unsaturated aldehyde, 2-propenal (acrolein). The objective of this study was to characterize the valence cationic states of these molecules with vibrational structural resolution.

  20. Modification of multi-walled carbon nanotubes with tannic acid for the adsorption of La, Tb and Lu ions

    International Nuclear Information System (INIS)

    Tong, S.; Zhao, S.; Zhou, W.; Jia, Q.; Li, R.

    2011-01-01

    We have prepared an environmental friendly sorbent by modifying multi-walled carbon nanotubes with tannic acid. The adsorption of La (III), Tb (III) and Lu (III) as a function of contact time, initial solution pH, and quantity of adsorbent was studied using a batch technique. Both Langmuir and Freundlich isotherms can be used to describe the process. The major adsorption mechanisms were attributed to ion exchange and surface complexation. The kinetics of the adsorption follows a pseudo-second-order model. The thermodynamic functions ΔH, ΔG, and ΔS indicate that the sorption is endothermically driven. The adsorbed ions can be readily desorbed from the surface with 1 M hydrochloric acid. (author)

  1. Transition Metal Ion Implantation into Diamond-Like Carbon Coatings: Development of a Base Material for Gas Sensing Applications

    Directory of Open Access Journals (Sweden)

    Andreas Markwitz

    2015-01-01

    Full Text Available Micrometre thick diamond-like carbon (DLC coatings produced by direct ion deposition were implanted with 30 keV Ar+ and transition metal ions in the lower percentage (<10 at.% range. Theoretical calculations showed that the ions are implanted just beneath the surface, which was confirmed with RBS measurements. Atomic force microscope scans revealed that the surface roughness increases when implanted with Ar+ and Cu+ ions, whereas a smoothing of the surface from 5.2 to 2.7 nm and a grain size reduction from 175 to 93 nm are measured for Ag+ implanted coatings with a fluence of 1.24×1016 at. cm−2. Calculated hydrogen and carbon depth profiles showed surprisingly significant changes in concentrations in the near-surface region of the DLC coatings, particularly when implanted with Ag+ ions. Hydrogen accumulates up to 32 at.% and the minimum of the carbon distribution is shifted towards the surface which may be the cause of the surface smoothing effect. The ion implantations caused an increase in electrical conductivity of the DLC coatings, which is important for the development of solid-state gas sensors based on DLC coatings.

  2. Single amino acids in the carboxyl terminal domain of aquaporin-1 contribute to cGMP-dependent ion channel activation

    Directory of Open Access Journals (Sweden)

    Yool Andrea J

    2003-10-01

    Full Text Available Abstract Background Aquaporin-1 (AQP1 functions as an osmotic water channel and a gated cation channel. Activation of the AQP1 ion conductance by intracellular cGMP was hypothesized to involve the carboxyl (C- terminus, based on amino acid sequence alignments with cyclic-nucleotide-gated channels and cGMP-selective phosphodiesterases. Results Voltage clamp analyses of human AQP1 channels expressed in Xenopus oocytes demonstrated that the nitric oxide donor, sodium nitroprusside (SNP; 3–14 mM activated the ionic conductance response in a dose-dependent manner. Block of soluble guanylate cyclase prevented the response. Enzyme immunoassays confirmed a linear dose-dependent relationship between SNP and the resulting intracellular cGMP levels (up to 1700 fmol cGMP /oocyte at 14 mM SNP. Results here are the first to show that the efficacy of ion channel activation is decreased by mutations of AQP1 at conserved residues in the C-terminal domain (aspartate D237 and lysine K243. Conclusions These data support the idea that the limited amino acid sequence similarities found between three diverse classes of cGMP-binding proteins are significant to the function of AQP1 as a cGMP-gated ion channel, and provide direct evidence for the involvement of the AQP1 C-terminal domain in cGMP-mediated ion channel activation.

  3. Sensing properties of separative paper-based extended-gate ion-sensitive field-effect transistor for cost effective pH sensor applications

    Science.gov (United States)

    Cho, Won-Ju; Lim, Cheol-Min

    2018-02-01

    In this study, we developed a cost-effective ion-sensing field-effect transistor (FET) with an extended gate (EG) fabricated on a separative paper substrate. The pH sensing characteristics of the paper EG was compared with those of other EGs fabricated on silicon, glass, or polyimide substrates. The fabricated paper-based EGFET exhibited excellent sensitivity close to the Nernst response limit as well as to that of the other substrate-based EGFETs. In addition, we found that all EGFETs, regardless of the substrate, have similar non-ideal behavior, i.e., drift phenomenon and hysteresis width. To investigate the degradation and durability of the paper EG after prolonged use, aging-effect tests were carried out in terms of the hysteresis width and sensitivity over a course of 30 days. As a result, the paper EG maintained stable pH sensing characteristics after 30 days. Therefore, we expect that paper EGFETs can provide a cost-effective sensor platform.

  4. Target-induced formation of gold amalgamation on DNA-based sensing platform for electrochemical monitoring of mercury ion coupling with cycling signal amplification strategy.

    Science.gov (United States)

    Chen, Jinfeng; Tang, Juan; Zhou, Jun; Zhang, Lan; Chen, Guonan; Tang, Dianping

    2014-01-31

    Heavy metal ion pollution poses severe risks in human health and environmental pollutant, because of the likelihood of bioaccumulation and toxicity. Driven by the requirement to monitor trace-level mercury ion (Hg(2+)), herein we construct a new DNA-based sensor for sensitive electrochemical monitoring of Hg(2+) by coupling target-induced formation of gold amalgamation on DNA-based sensing platform with gold amalgamation-catalyzed cycling signal amplification strategy. The sensor was simply prepared by covalent conjugation of aminated poly-T(25) oligonucleotide onto the glassy carbon electrode by typical carbodiimide coupling. Upon introduction of target analyte, Hg(2+) ion was intercalated into the DNA polyion complex membrane based on T-Hg(2+)-T coordination chemistry. The chelated Hg(2+) ion could induce the formation of gold amalgamation, which could catalyze the p-nitrophenol with the aid of NaBH4 and Ru(NH3)6(3+) for cycling signal amplification. Experimental results indicated that the electronic signal of our system increased with the increasing Hg(2+) level in the sample, and has a detection limit of 0.02nM with a dynamic range of up to 1000nM Hg(2+). The strategy afforded exquisite selectivity for Hg(2+) against other environmentally related metal ions. In addition, the methodology was evaluated for the analysis of Hg(2+) in spiked tap-water samples, and the recovery was 87.9-113.8%. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Expression of fatty acid sensing G-protein coupled receptors in peripartal Holstein cows.

    Science.gov (United States)

    Agrawal, Alea; Alharthi, Abdulrahman; Vailati-Riboni, Mario; Zhou, Zheng; Loor, Juan J

    2017-01-01

    G-protein coupled receptors (GPCR), also referred as Free Fatty Acid Receptors (FFAR), are widely studied within human medicine as drug targets for metabolic disorders. To combat metabolic disorders prevalent in dairy cows during the transition period, which co-occur with negative energy balance and changes to lipid and glucose metabolism, it may be helpful to identify locations and roles of FFAR and other members of the GPCR family in bovine tissues. Quantitative RT-PCR (qPCR) of subcutaneous adipose, liver, and PMNL samples during the transition period (-10, +7, and +20 or +30 d) were used for expression profiling of medium- (MCFA) and long-chain fatty acid (LCFA) receptors GPR120 and GPR40 , MCFA receptor GPR84 , and niacin receptor HCAR2/3 . Adipose samples were obtained from cows with either high (HI; BCS ≥ 3.75) or low (LO; BCS ≤ 3.25) body condition score (BCS) to examine whether FFAR expression is correlated with this indicator of health and body reserves. Supplementation of rumen-protected methionine (MET), which may improve immune function and production postpartum, was also compared with unsupplemented control (CON) cows for liver and blood polymorphonuclear leukocytes (PMNL) samples. In adipose tissue, GPR84 and GPR120 were differentially expressed over time, while GPR40 was not expressed; in PMNL, GPR40 was differentially expressed over time and between MET vs. CON, GPR84 expression differed only between dietary groups, and GPR120 was not expressed; in liver, GPCR were either not expressed or barely detectable. The data indicate that there is likely not a direct role in liver for the selected GPCR during the transition period, but they do play variable roles in adipose and PMN. In future, these receptors may prove useful targets and/or markers for peripartal metabolism and immunity.

  6. An OmpA Family Protein, a Target of the GinI/GinR Quorum-Sensing System in Gluconacetobacter intermedius, Controls Acetic Acid Fermentation▿ †

    Science.gov (United States)

    Iida, Aya; Ohnishi, Yasuo; Horinouchi, Sueharu

    2008-01-01

    Via N-acylhomoserine lactones, the GinI/GinR quorum-sensing system in Gluconacetobacter intermedius NCI1051, a gram-negative acetic acid bacterium, represses acetic acid and gluconic acid fermentation. Two-dimensional polyacrylamide gel electrophoretic analysis of protein profiles of strain NCI1051 and ginI and ginR mutants identified a protein that was produced in response to the GinI/GinR regulatory system. Cloning and nucleotide sequencing of the gene encoding this protein revealed that it encoded an OmpA family protein, named GmpA. gmpA was a member of the gene cluster containing three adjacent homologous genes, gmpA to gmpC, the organization of which appeared to be unique to vinegar producers, including “Gluconacetobacter polyoxogenes.” In addition, GmpA was unique among the OmpA family proteins in that its N-terminal membrane domain forming eight antiparallel transmembrane β-strands contained an extra sequence in one of the surface-exposed loops. Transcriptional analysis showed that only gmpA of the three adjacent gmp genes was activated by the GinI/GinR quorum-sensing system. However, gmpA was not controlled directly by GinR but was controlled by an 89-amino-acid protein, GinA, a target of this quorum-sensing system. A gmpA mutant grew more rapidly in the presence of 2% (vol/vol) ethanol and accumulated acetic acid and gluconic acid in greater final yields than strain NCI1051. Thus,