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Sample records for acid sensing ion

  1. Amino acid-sensing ion channels in plants

    Energy Technology Data Exchange (ETDEWEB)

    Spalding, Edgar P.

    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.

  2. Structural plasticity and dynamic selectivity of acid sensing ion channel–toxin complexes

    OpenAIRE

    Baconguis, Isabelle; Gouaux, Eric

    2012-01-01

    Acid sensing ion channels (ASICs) are voltage-independent, amiloride-sensitive channels implicated in diverse physiological processes ranging from nociception to taste. Despite the importance of ASICs in physiology, we know little about the mechanism of channel activation. Here we show that psalmotoxin activates non- and sodium-selective currents in chicken ASIC1a at pH 7.25 and 5.5, respectively. Crystal structures of ASIC1a – psalmotoxin complexes map the toxin binding site to the extracell...

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

    Science.gov (United States)

    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. PMID:27493834

  4. Insight toward epithelial Na+ channel mechanism revealed by the acid-sensing ion channel 1 structure.

    Science.gov (United States)

    Stockand, James D; Staruschenko, Alexander; Pochynyuk, Oleh; Booth, Rachell E; Silverthorn, Dee U

    2008-09-01

    The epithelial Na(+) channel/degenerin (ENaC/DEG) protein family includes a diverse group of ion channels, including nonvoltage-gated Na(+) channels of epithelia and neurons, and the acid-sensing ion channel 1 (ASIC1). In mammalian epithelia, ENaC helps regulate Na(+) and associated water transport, making it a critical determinant of systemic blood pressure and pulmonary mucosal fluidity. In the nervous system, ENaC/DEG proteins are related to sensory transduction. While the importance and physiological function of these ion channels are established, less is known about their structure. One hallmark of the ENaC/DEG channel family is that each channel subunit has only two transmembrane domains connected by an exceedingly large extracellular loop. This subunit structure was recently confirmed when Jasti and colleagues determined the crystal structure of chicken ASIC1, a neuronal acid-sensing ENaC/DEG channel. By mapping ENaC to the structural coordinates of cASIC1, as we do here, we hope to provide insight toward ENaC structure. ENaC, like ASIC1, appears to be a trimeric channel containing 1alpha, 1beta, and 1gamma subunit. Heterotrimeric ENaC and monomeric ENaC subunits within the trimer possibly contain many of the major secondary, tertiary, and quaternary features identified in cASIC1 with a few subtle but critical differences. These differences are expected to have profound effects on channel behavior. In particular, they may contribute to ENaC insensitivity to acid and to its constitutive activity in the absence of time- and ligand-dependent inactivation. Experiments resulting from this comparison of cASIC1 and ENaC may help clarify unresolved issues related to ENaC architecture, and may help identify secondary structures and residues critical to ENaC function.

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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 NO2− 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

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

    Directory of Open Access Journals (Sweden)

    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.

  8. Structural plasticity and dynamic selectivity of acid-sensing ion channel-spider toxin complexes

    Energy Technology Data Exchange (ETDEWEB)

    Baconguis, Isabelle; Gouaux, Eric [Oregon HSU

    2012-07-29

    Acid-sensing ion channels (ASICs) are voltage-independent, amiloride-sensitive channels involved in diverse physiological processes ranging from nociception to taste. Despite the importance of ASICs in physiology, we know little about the mechanism of channel activation. Here we show that psalmotoxin activates non-selective and Na+-selective currents in chicken ASIC1a at pH7.25 and 5.5, respectively. Crystal structures of ASIC1a–psalmotoxin complexes map the toxin binding site to the extracellular domain and show how toxin binding triggers an expansion of the extracellular vestibule and stabilization of the open channel pore. At pH7.25 the pore is approximately 10Å in diameter, whereas at pH5.5 the pore is largely hydrophobic and elliptical in cross-section with dimensions of approximately 5 by 7Å, consistent with a barrier mechanism for ion selectivity. These studies define mechanisms for activation of ASICs, illuminate the basis for dynamic ion selectivity and provide the blueprints for new therapeutic agents.

  9. Does closure of acid-sensing ion channels reduce ischemia/reperfusion injury in the rat brain?

    Institute of Scientific and Technical Information of China (English)

    Jie Wang; Yinghui Xu; Zhigang Lian; Jian Zhang; Tingzhun Zhu; Mengkao Li; Yi Wei; Bin Dong

    2013-01-01

    Acidosis is a common characteristic of brain damage. Because studies have shown that permeable Ca2+-acid-sensing ion channels can mediate the toxic effects of calcium ions, they have become new targets against pain and various intracranial diseases. However, the mechanism associated with expression of these channels remains unclear. This study sought to observe the expression characteristics of permeable Ca2+-acid-sensing ion channels during different reperfusion inflows in rats after cerebral ischemia. The rat models were randomly divided into three groups: adaptive ischemia/reperfusion group, one-time ischemia/reperfusion group, and severe cerebral ischemic injury group. Western blot assays and immunofluorescence staining results exhibited that when compared with the one-time ischemia/reperfusion group, acid-sensing ion channel 3 and Bcl-x/l expression decreased in the adaptive ischemia/reperfusion group. Calmodulin expression was lowest in the adaptive ischemia/reperfusion group. Following adaptive reperfusion, common carotid artery flow was close to normal, and the pH value improved. Results verified that adaptive reperfusion following cerebral ischemia can suppress acid-sensing ion channel 3 expression, significantly reduce Ca2+ influx, inhibit calcium overload, and diminish Ca2+ toxicity. The effects of adaptive ischemia/reperfusion on suppressing cell apoptosis and relieving brain damage were better than that of one-time ischemia/reperfusion.

  10. 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.

  11. 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.

  12. Acid-sensing ion channels regulate spontaneous inhibitory activity in the hippocampus: possible implications for epilepsy.

    Science.gov (United States)

    Ievglevskyi, O; Isaev, D; Netsyk, O; Romanov, A; Fedoriuk, M; Maximyuk, O; Isaeva, E; Akaike, N; Krishtal, O

    2016-08-01

    Acid-sensing ion channels (ASICs) play an important role in numerous functions in the central and peripheral nervous systems ranging from memory and emotions to pain. The data correspond to a recent notion that each neuron and many glial cells of the mammalian brain express at least one member of the ASIC family. However, the mechanisms underlying the involvement of ASICs in neuronal activity are poorly understood. However, there are two exceptions, namely, the straightforward role of ASICs in proton-based synaptic transmission in certain brain areas and the role of the Ca(2+)-permeable ASIC1a subtype in ischaemic cell death. Using a novel orthosteric ASIC antagonist, we have found that ASICs specifically control the frequency of spontaneous inhibitory synaptic activity in the hippocampus. Inhibition of ASICs leads to a strong increase in the frequency of spontaneous inhibitory postsynaptic currents. This effect is presynaptic because it is fully reproducible in single synaptic boutons attached to isolated hippocampal neurons. In concert with this observation, inhibition of the ASIC current diminishes epileptic discharges in a low Mg(2+) model of epilepsy in hippocampal slices and significantly reduces kainate-induced discharges in the hippocampus in vivo Our results reveal a significant novel role for ASICs.This article is part of the themed issue 'Evolution brings Ca(2+) and ATP together to control life and death'. PMID:27377725

  13. Ischemic postconditioning protects against ischemic brain injury by up-regulation of acid-sensing ion channel 2a

    Institute of Scientific and Technical Information of China (English)

    Wang-sheng Duanmu; Liu Cao; Jing-yu Chen; Hong-fei Ge; Rong Hu; Hua Feng

    2016-01-01

    Ischemic postconditioning renders brain tissue tolerant to brain ischemia, thereby alleviating ischemic brain injury. However, the exact mechanism of action is still unclear. In this study, a rat model of global brain ischemia was subjected to ischemic postconditioning treat-ment using the vessel occlusion method. After 2 hours of ischemia, the bilateral common carotid arteries were blocked immediately for 10 seconds and then perfused for 10 seconds. This procedure was repeated six times. Ischemic postconditioning was found to mitigate hippocampal CA1 neuronal damage in rats with brain ischemia, and up-regulate acid-sensing ion channel 2a expression at the mRNA and protein level. These ifndings suggest that ischemic postconditioning up-regulates acid-sensing ion channel 2a expression in the rat hippo-campus after global brain ischemia, which promotes neuronal tolerance to ischemic brain injury.

  14. 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.

  15. Interaction of Acid-sensing Ion Channel (ASIC) 1 with the Tarantula Toxin Psalmotoxin 1 is State Dependent

    OpenAIRE

    Chen, Xuanmao; Kalbacher, Hubert; Gründer, Stefan

    2006-01-01

    Acid-sensing ion channels (ASICs) are Na+ channels gated by extracellular H+. Six ASIC subunits that are expressed in neurons have been characterized. The tarantula toxin psalmotoxin 1 has been reported to potently and specifically inhibit homomeric ASIC1a and has been useful to characterize ASICs in neurons. Recently we have shown that psalmotoxin 1 inhibits ASIC1a by increasing its apparent affinity for H+. However, the mechanism by which PcTx1 increases the apparent H+ affinity remained un...

  16. The pharmacology and therapeutic potential of small molecule inhibitors of acid-sensing ion channels in stroke intervention

    Institute of Scientific and Technical Information of China (English)

    Tian-dong LENG; Zhi-gang XIONG

    2013-01-01

    In the nervous system,a decrease in extracellular pH is a common feature of various physiological and pathological processes,including synaptic transmission,cerebral ischemia,epilepsy,brain trauma,and tissue inflammation.Acid-sensing ion channels (ASICs) are proton-gated cation channels that are distributed throughout the central and peripheral nervous systems.Following the recent identification of ASICs as critical acid-sensing extracellular proton receptors,growing evidence has suggested that the activation of ASICs plays important roles in physiological processes such as nociception,mechanosensation,synaptic plasticity,learning and memory.However,the over-activation of ASICs is also linked to adverse outcomes for certain pathological processes,such as brain ischemia and multiple sclerosis.Based on the well-demonstrated role of ASlC1a activation in acidosis-mediated brain injury,small molecule inhibitors of ASIC1a may represent novel therapeutic agents for the treatment of neurological disorders,such as stroke.

  17. 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

  18. Expression in Pichia pastoris and characterization of APETx2, a specific inhibitor of acid sensing ion channel 3.

    Science.gov (United States)

    Anangi, Raveendra; Chen, Chih-Cheng; Lin, Yi-Wen; Cheng, Yuan-Ren; Cheng, Chun-Ho; Chen, Yi-Chun; Chu, Yuan-Ping; Chuang, Woei-Jer

    2010-12-01

    Acid sensing ion channels (ASICs) are family of proteins predominantly present in the central and peripheral nervous system. They are known to play important roles in the pathophysiology of pain and ischemic stroke. APETx2 is a potent and selective inhibitor of ASIC3-containing channels and was isolated from sea anemone Anthopleura elegantissima. To facilitate the study on the molecular determinants of ASIC3-ligand interactions, we expressed recombinant APETx2 in the Pichia pastoris (P. pastoris) expression system and purified it to homogeneity. Recombinant APETx2 produced in P. pastoris inhibited the acid-evoked ASIC3 current with the IC(50) value of 37.3 nM. The potency of recombinant toxin is similar to that of native APETx2. The sequential assignment and structure analysis of APETx2 were obtained by 2D and 3D (15)N-edited NMR spectra. Our NMR data suggests that APETx2 produced in P. pastoris retained its native fold. The results presented here provide the first direct evidence that highly disulfide bonded peptide inhibitor of ASIC3, APETx2, can be expressed in P. pastoris with correct fold and high yield. We also showed that the R17A mutant exhibited a decrease in activity, suggesting the feasibility of the use of this expression system to study the interactions between APETx2 and ASIC3. These evidences may serve as the basis for understanding the selectivity and activity of APETx2. PMID:20813121

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

    Science.gov (United States)

    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 differential subcellular localization remained to be further elucidated. By constructing ASIC2 chimeras, we found that the first transmembrane (TM1) domain and the proximal post-TM1 domain (17 amino acids) of ASIC2a are critical for membrane targeting of the proteins. We also observed that replacement of corresponding residues in ASIC2b by those of ASIC2a conferred proton-sensitivity as well as surface expression to ASIC2b. We finally confirmed that ASIC2b is delivered to the cell surface from the ER by forming heteromers with ASIC2a, and that the N-terminal region of ASIC2a is additionally required for the ASIC2a-dependent membrane targeting of ASIC2b. Together, our study supports an important role of ASIC2a in membrane targeting of ASIC2b. PMID:27477936

  20. 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.

  1. Highly Luminescent Microporous Organic Polymer with Lewis Acidic Boron Sites on the Pore Surface: Ratiometric Sensing and Capture of F(-) Ions.

    Science.gov (United States)

    Suresh, Venkata M; Bandyopadhyay, Arkamita; Roy, Syamantak; Pati, Swapan K; Maji, Tapas Kumar

    2015-07-20

    Reversible and selective capture/detection of F(-) ions in water is of the utmost importance, as excess intake leads to adverse effects on human health. Highly robust Lewis acidic luminescent porous organic materials have potential for efficient sequestration and detection of F(-) ions. Herein, the rational design and synthesis of a boron-based, Lewis acidic microporous organic polymer (BMOP) derived from tris(4-bromo-2,3,5,6-tetramethylphenyl)boron nodes and diethynylbiphenyl linkers with a pore size of 1.08 nm for selective turn-on sensing and capture of F(-) ion are reported. The presence of a vacant pπ orbital on the boron center of BMOP results in intramolecular charge transfer (ICT) from the linker to boron. BMOP shows selective turn-on blue emission for F(-) ions in aqueous mixtures with a detection limit of 2.6 μM. Strong B-F interactions facilitate rapid sequestration of F(-) by BMOP. The ICT emission of BMOP can be reversibly regenerated by addition of an excess of water, and the polymer can be reused several times. PMID:26074403

  2. 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.

  3. Cyclisation Increases the Stability of the Sea Anemone Peptide APETx2 but Decreases Its Activity at Acid-Sensing Ion Channel 3

    Directory of Open Access Journals (Sweden)

    Lachlan D. Rash

    2012-07-01

    Full Text Available APETx2 is a peptide isolated from the sea anemone Anthopleura elegantissima. It is the most potent and selective inhibitor of acid-sensing ion channel 3 (ASIC3 and it is currently in preclinical studies as a novel analgesic for the treatment of chronic inflammatory pain. As a peptide it faces many challenges in the drug development process, including the potential lack of stability often associated with therapeutic peptides. In this study we determined the susceptibility of wild-type APETx2 to trypsin and pepsin and tested the applicability of backbone cyclisation as a strategy to improve its resistance to enzymatic degradation. Cyclisation with either a six-, seven- or eight-residue linker vastly improved the protease resistance of APETx2 but substantially decreased its potency against ASIC3. This suggests that either the N- or C-terminus of APETx2 is involved in its interaction with the channel, which we confirmed by making N- and C-terminal truncations. Truncation of either terminus, but especially the N-terminus, has detrimental effects on the ability of APETx2 to inhibit ASIC3. The current work indicates that cyclisation is unlikely to be a suitable strategy for stabilising APETx2, unless linkers can be engineered that do not interfere with binding to ASIC3.

  4. The function and regulation of acid-sensing ion channels (ASICs) and the epithelial Na(+) channel (ENaC): IUPHAR Review 19.

    Science.gov (United States)

    Boscardin, Emilie; Alijevic, Omar; Hummler, Edith; Frateschi, Simona; Kellenberger, Stephan

    2016-09-01

    Acid-sensing ion channels (ASICs) and the epithelial Na(+) channel (ENaC) are both members of the ENaC/degenerin family of amiloride-sensitive Na(+) channels. ASICs act as proton sensors in the nervous system where they contribute, besides other roles, to fear behaviour, learning and pain sensation. ENaC mediates Na(+) reabsorption across epithelia of the distal kidney and colon and of the airways. ENaC is a clinically used drug target in the context of hypertension and cystic fibrosis, while ASIC is an interesting potential target. Following a brief introduction, here we will review selected aspects of ASIC and ENaC function. We discuss the origin and nature of pH changes in the brain and the involvement of ASICs in synaptic signalling. We expose how in the peripheral nervous system, ASICs cover together with other ion channels a wide pH range as proton sensors. We introduce the mechanisms of aldosterone-dependent ENaC regulation and the evidence for an aldosterone-independent control of ENaC activity, such as regulation by dietary K(+) . We then provide an overview of the regulation of ENaC by proteases, a topic of increasing interest over the past few years. In spite of the profound differences in the physiological and pathological roles of ASICs and ENaC, these channels share many basic functional and structural properties. It is likely that further research will identify physiological contexts in which ASICs and ENaC have similar or overlapping roles. PMID:27278329

  5. Rotation sensing with trapped ions

    CERN Document Server

    Campbell, W C

    2016-01-01

    We present a protocol for using trapped ions to measure rotations via matter-wave Sagnac interferometry. The trap allows the interferometer to enclose a large area in a compact apparatus through repeated round-trips in a Sagnac geometry. We show how a uniform magnetic field can be used to close the interferometer over a large dynamic range in rotation speed and measurement bandwidth without losing contrast. Since this technique does not require the ions to be confined in the Lamb-Dicke regime, thermal states with many phonons should be sufficient for operation.

  6. Copper ion sensing with fluorescent electrospun nanofibers

    Science.gov (United States)

    Ongun, Merve Zeyrek; Ertekin, Kadriye; Gocmenturk, Mustafa; Ergun, Yavuz; Suslu, Aslıhan

    2012-05-01

    In this work, the use of electrospun nanofibrous materials as highly responsive fluorescence quenching-based copper sensitive chemosensor is reported. Poly(methyl methacrylate) and ethyl cellulose were used as polymeric support materials. Sensing slides were fabricated by electrospinning technique. Copper sensors based on the change in the fluorescence signal intensity of fluoroionophore; N'-3-(4-(dimethylamino phenly)allylidene)isonicotinohydrazide. The sensor slides exhibited high sensitivities due to the high surface area of the nanofibrous membrane structures. The preliminary results of Stern-Volmer analysis show that the sensitivities of electrospun nanofibrous membranes to detect Cu(II) ions are 6-20-fold higher than those of the continuous thin films. By this way we obtained linear calibration plots for Cu(II) ions in the concentration range of 10-12-10-5 M. The response times of the sensing slides were less than 1 min. Stability of the employed ionophore in the matrix materials was excellent and when stored in the ambient air of the laboratory there was no significant drift in signal intensity after 6 months. Our stability tests are still in progress.

  7. Modeling ion sensing in molecular electronics

    Science.gov (United States)

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

    2014-02-01

    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 (Ca2+), and hydronium ions (H3O+) 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, C9H7NS2), 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.

  8. Modeling ion sensing in molecular electronics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Caroline J.; Smeu, Manuel, E-mail: manuel.smeu@northwestern.edu; Ratner, Mark A., E-mail: ratner@northwestern.edu [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208 (United States)

    2014-02-07

    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{sup +}), alkali metal cations (M{sup +}), calcium ions (Ca{sup 2+}), and hydronium ions (H{sub 3}O{sup +}) 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{sub 9}H{sub 7}NS{sub 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{sup +} + QDT species containing monovalent cations, where M{sup +} = H{sup +}, Li{sup +}, Na{sup +}, or K{sup +}. 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.

  9. A new ion sensing deep atomic force microscope

    Science.gov (United States)

    Drake, Barney; Randall, Connor; Bridges, Daniel; Hansma, Paul K.

    2014-08-01

    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.

  10. 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.

  11. Wellcome Prize Lecture. Cell surface, ion-sensing receptors.

    Science.gov (United States)

    Riccardi, Daniela

    2002-07-01

    Changes in extracellular calcium (Ca(2+)o) concentration ([Ca2+]o) affect kidney function both under basal and hormone-stimulated conditions. The molecular identification of an extracellular Ca(2+)-sensing receptor (CaR) has confirmed a direct role of Ca(2+)o on parathyroid and kidney function (i.e. independent of calciotropic hormones) as a modulator of Ca2+ homeostasis. In addition, evidence accumulated over the last 10 years has shown that CaR is also expressed in regions outside the calcium homeostatic system where its role is largely undefined but seems to be linked to regulation of local ionic homeostasis. The parathyroid and kidney CaRs are 1081 and 1079 amino acids long, respectively, and belong to the type III family of G protein-coupled receptors (GPCRs), which includes other CaRs, metabotropic glutamate receptors and putative vomeronasal organ receptors. For the CaR, its low (millimolar) affinity for Ca2+, its positive cooperativity and its large ion-sensing extracellular domain, indicate that the receptor is more sensitive to changes in net cationic charge rather than to a specific ligand. Mg2+, trivalent cations of the lanthanide series and polyvalent cations such as spermine and aminoglycoside antibiotics can all activate the receptor in vitro with EC50 values in the micromolar range for trivalent and polyvalent cations or in the millimolar range for Ca2+ and Mg2+. In addition to true CaR agonists, CaR sensitivity to Ca(2+)o is also susceptible to allosteric modulation by ionic strength, L-amino acids and by pharmacological agents. This review will address endogenous and exogenous CaR agonists, the role of the receptor in the calcium homeostatic system and some speculation on possible role(s) of the CaR in regions not involved in mineral ion homeostasis. PMID:12392104

  12. Wellcome Prize Lecture. Cell surface, ion-sensing receptors.

    Science.gov (United States)

    Riccardi, Daniela

    2002-07-01

    Changes in extracellular calcium (Ca(2+)o) concentration ([Ca2+]o) affect kidney function both under basal and hormone-stimulated conditions. The molecular identification of an extracellular Ca(2+)-sensing receptor (CaR) has confirmed a direct role of Ca(2+)o on parathyroid and kidney function (i.e. independent of calciotropic hormones) as a modulator of Ca2+ homeostasis. In addition, evidence accumulated over the last 10 years has shown that CaR is also expressed in regions outside the calcium homeostatic system where its role is largely undefined but seems to be linked to regulation of local ionic homeostasis. The parathyroid and kidney CaRs are 1081 and 1079 amino acids long, respectively, and belong to the type III family of G protein-coupled receptors (GPCRs), which includes other CaRs, metabotropic glutamate receptors and putative vomeronasal organ receptors. For the CaR, its low (millimolar) affinity for Ca2+, its positive cooperativity and its large ion-sensing extracellular domain, indicate that the receptor is more sensitive to changes in net cationic charge rather than to a specific ligand. Mg2+, trivalent cations of the lanthanide series and polyvalent cations such as spermine and aminoglycoside antibiotics can all activate the receptor in vitro with EC50 values in the micromolar range for trivalent and polyvalent cations or in the millimolar range for Ca2+ and Mg2+. In addition to true CaR agonists, CaR sensitivity to Ca(2+)o is also susceptible to allosteric modulation by ionic strength, L-amino acids and by pharmacological agents. This review will address endogenous and exogenous CaR agonists, the role of the receptor in the calcium homeostatic system and some speculation on possible role(s) of the CaR in regions not involved in mineral ion homeostasis.

  13. Functional Expression in Escherichia coli of the Disulfide-Rich Sea Anemone Peptide APETx2, a Potent Blocker of Acid-Sensing Ion Channel 3

    Directory of Open Access Journals (Sweden)

    Glenn F. King

    2012-07-01

    Full Text Available Acid-sensing ion channels (ASICs are proton-gated sodium channels present in the central and peripheral nervous system of chordates. ASIC3 is highly expressed in sensory neurons and plays an important role in inflammatory and ischemic pain. Thus, specific inhibitors of ASIC3 have the potential to be developed as novel analgesics. APETx2, isolated from the sea anemone Anthopleura elegantissima, is the most potent and selective inhibitor of ASIC3-containing channels. However, the mechanism of action of APETx2 and the molecular basis for its interaction with ASIC3 is not known. In order to assist in characterizing the ASIC3-APETx2 interaction, we developed an efficient and cost-effective Escherichia coli periplasmic expression system for the production of APETx2. NMR studies on uniformly 13C/15N-labelled APETx2 produced in E. coli showed that the recombinant peptide adopts the native conformation. Recombinant APETx2 is equipotent with synthetic APETx2 at inhibiting ASIC3 channels expressed in Xenopus oocytes. Using this system we mutated Phe15 to Ala, which caused a profound loss of APETx2’s activity on ASIC3. These findings suggest that this expression system can be used to produce mutant versions of APETx2 in order to facilitate structure-activity relationship studies.

  14. 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. T....... 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.......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...

  15. Effect of acid sensing ion channels on respiratory regulation by central chemoreceptors%酸敏感离子通道在中枢化学感受器呼吸调节中的作用

    Institute of Scientific and Technical Information of China (English)

    李丽; 刘文彦; 高波

    2014-01-01

    目的:探讨脑室内注射酸化人工脑脊液(artificialcerebrospinalfluid,aCSF)引起的呼吸效应及酸敏感离子通道( acid sensing ion channels , ASICs )在此过程中的作用。方法:健康成年SD大鼠30只,随机分为aCSF(pH 7.4)对照组、aCSF(pH 6.5)组、ASICs阻断剂阿米洛利(amiloride)对照组、amiloride+aCSF(pH 6.5)组、ASIC1a阻断剂psalmotoxin 1(PcTx1)对照组及PcTx1+aCSF(pH 6.5)组。通过膈肌肌电记录脑室内注射酸化aCSF后呼吸的变化;通过脑室内先注射阿米洛利和PcTx1再注射酸化aCSF的方法,观察酸敏感离子通道在中枢化学感受器呼吸调节中的作用。结果:脑室内注射酸化aCSF后,呼吸较注射前明显兴奋(P<0.05);脑室内注射阿米洛利能完全阻断脑室内注射酸化aCSF引起的呼吸兴奋;脑室内注射PcTx1能部分阻断脑室内注射酸化aCSF引起的呼吸兴奋。结论:ASICs是参与中枢化学感受器呼吸调节的关键离子通道,ASIC1a则发挥了部分作用。%[ABSTRACT]AIM:Toinvestigatetheeffectofintracerebroventricular(icv)injectionofacidulatedartificialce-rebrospinal fluid ( aCSF ) on the respiratory reactions and the functions of acid sensing ion channels ( ASICs ) in this process.METHODS:Healthy adult SD rats (n=30) were divided into aCSF with pH 7.4 control group, aCSF with pH 6.5 group, amiloride control group, amiloride plus aCSF with pH 6.5 group, psalmotoxin 1 (PcTx1) control group and PcTx1 plus aCSF with pH 6.5 group.The electromyogram (EMG) of the diaphragm was monitored to observe the respirato-ry responses induced by icv injection of acidulated aCSF .The ASICs blockers were also injected into the lateral cerebral ventricle firstly and acidulated aCSF was injected following the ASICs blockers to observe the effect of ASICs on the respira -tory regulation by the central chemoreceptor .RESULTS:After icv injection of acidulated aCSF , the

  16. Glass-like carbon, pyrolytic graphite or nanostructured carbon for electrochemical sensing of bismuth ion?

    Directory of Open Access Journals (Sweden)

    Jadranka Milikić

    2016-06-01

    Full Text Available Different carbon electrodes were explored for application in electroanalysis, namely for sensing of bismuth ion as model analyte. Carbon materials tested included glassy carbon, basal and edge plane pyrolytic graphite, as well as nanostructured carbonized polyaniline prepared in the presence of 3,5-dinitrosalicylic acid. Bismuth ion was chosen as model analyte as protocol for its detection and quantifications is still to be determined. Herein, anodic stripping voltammetry was used with study of effect of several parameters such as scan rate and deposition time. Electrode based on carbonized polyaniline showed the highest activity for bismuth ion sensing in terms of the highest current densities recorded both in a laboratory and in real sample, while basal plane pyrolytic graphite electrode gave the lowest limit of detection.

  17. Expression of acid-sensing ion channels in rat articular cartilage with adjuvant arthritis%酸敏感离子通道在大鼠佐剂性关节炎关节软骨中的表达

    Institute of Scientific and Technical Information of China (English)

    袁凤来; 陈飞虎; 黄学应; 李霞; 吴繁荣; 阮晶晶; 李俊

    2008-01-01

    Objective To study the expression and significance of acid-sensing ion channels(ASICs)in rat articular cartilage with adjuvant arthritis. Methods Complete Freund's adjuvant(CFA) was prepared by suspending heat-killed Bacillus Calmette Guerin(BCG) in liquid paraffin at 10 mg/ml. CFA-induced arthritis was developed by injection of 100 μl CFA emulsion intradermally into the right hind paw. The morphological changes of articular tissues was observed by light microscope; RT-PCR and immunoblotting analyses were used to detect ASICs in rat articular cartilage with adjuvant arthritis. Results RT-PCR and western blot showed that ASIC1a, ASIC2a and ASIC3 were present in the articular cartilage of normal and model group, the ASICs mRNA levels in the model group were higher than in the normal group detected by semiquantitative analysis (P<0.01), ASICs protein levels in model group were higher than those in the normal group (P<0.01) when examined by immunoblotting. Conclusion The results show that the expression of ASICs in AA articular cartilage is enhanced and it may be related with articular cartilage breakdown.%目的 检测酸敏感离子通道(ASICs)在大鼠佐剂性关节炎关节软骨中的表达情况.方法 大鼠右侧后足跖皮内注射弗氏完全佐剂(CFA)诱导佐剂性关节炎(AA)大鼠模型,用半定量反转录-聚合酶链反应(RT-PCR)和Western blot方法检测ASICs在AA大鼠关节软骨的表达.结果 经半定量RT-PCR分析,ASIC1a、ASIC2a和ASIC3在AA大鼠关节软骨中的表达量明显高于正常组,差异有统计学意义(P<0.01);Western blot进一步检测显示蛋白表达的变化与mRNA变化一致.结论 AA大鼠关节软骨中ASICs的表达增多,可能与关节软骨破坏有关.

  18. Beyond potentiometry: robust electrochemical ion sensor concepts in view of remote chemical sensing.

    Science.gov (United States)

    Bakker, Eric; Bhakthavatsalam, Vishnupriya; Gemene, Kebede L

    2008-05-15

    For about 100 years, potentiometry with ion-selective electrodes has been one of the dominating electroanalytical techniques. While great advances in terms of selective chemistries and materials have been achieved in recent years, the basic manner in which ion-selective membranes are used has not fundamentally changed. The potential readings are directly co-dependent on the potential at the reference electrode, which requires maintenance and for which very few accepted alternatives have been proposed. Fouling or clogging of the exposed electrode surfaces will lead to changes in the observed potential. At the same time, the Nernst equation predicts quite small potential changes, on the order of millivolts for concentration changes on the order of a factor two, making frequent recalibration, accurate temperature control and electrode maintenance key requirements of routine analytical measurements. While the relatively advanced selective materials developed for ion-selective sensors would be highly attractive for low power remote sensing application, one should consider solutions beyond classical potentiometry to make this technology practically feasible. This paper evaluates some recent examples that may be attractive solutions to the stated problems that face potentiometric measurements. These include high-amplitude sensing approaches, with sensitivities that are an order of magnitude larger than predicted by the Nernst equation; backside calibration potentiometry, where knowledge of the magnitude of the potential is irrelevant and the system is evaluated from the backside of the membrane; controlled current coulometry with ion-selective membranes, an attractive technique for calibration-free reagent delivery without the need for standards or volumetry; localized electrochemical titrations at ion-selective membranes, making it possible to design sensors that directly monitor parameters such as total acidity for which volumetric techniques were traditionally used

  19. Colorimetric Sugar Sensing Using Boronic Acid-Substituted Azobenzenes

    OpenAIRE

    Yuya Egawa; Ryotaro Miki; Toshinobu Seki

    2014-01-01

    In association with increasing diabetes prevalence, it is desirable to develop new glucose sensing systems with low cost, ease of use, high stability and good portability. Boronic acid is one of the potential candidates for a future alternative to enzyme-based glucose sensors. Boronic acid derivatives have been widely used for the sugar recognition motif, because boronic acids bind adjacent diols to form cyclic boronate esters. In order to develop colorimetric sugar sensors, boronic acid-conj...

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

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Dietmar, E-mail: fink@daad-alumni.de [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Nuclear Physics Institute, Academy of Sciences of the Czech Republic, 250 68 Rez (Czech Republic); Munoz Hernandez, Gerardo [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Division de Ciencias Naturales e Ingenieria, Universidad Autonoma Metropolitana-Cuajimalpa, Pedro Antonio de los Santos 84, Col. Sn. Miguel Chapultepec, C.P. 11850, Mexico, D.F. (Mexico); Alfonta, Lital, E-mail: alfontal@bgu.ac.il [Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel)

    2012-02-15

    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. Quorum sensing mechanism in lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Hatice Yılmaz - Yıldıran

    2015-04-01

    and detection occurs as a consecution it is hard to understand their QS mechanism. In this review, connection between QS mechanism and some characteristics of lactic acid bacteria are evaluated such as concordance with its host, inhibition of pathogen development and colonization in gastrointestinal system, bacteriocin production, acid and bile resistance, adhesion to epithelium cells. Understanding QS mechanism of lactic acid bacteria will be useful to design metabiotics which is defined as novel probiotics.

  2. Synthesis of functionalized fluorescent gold nanoclusters for acid phosphatase sensing

    Science.gov (United States)

    Sun, Jian; Yang, Fan; Yang, Xiurong

    2015-10-01

    A novel and convenient one-pot but two-step synthesis of fluorescent gold nanoclusters, incorporating glutathione (GSH) and 11-mercaptoundecanoic acid (MUA) as the functionalized ligands (i.e. AuNCs@GSH/MUA), is demonstrated. Herein, the mixing of HAuCl4 and GSH in aqueous solution results in the immediate formation of non-fluorescent GSH-Au+ complexes, and then a class of ~2.6 nm GSH-coated AuNCs (AuNCs@GSH) with mild orange-yellow fluorescence after several days. Interestingly, the intense orange-red emitting ~1.7 nm AuNCs@GSH/MUA can be synthesized within seconds by introducing an alkaline aqueous solution of MUA into the GSH-Au+ complexes or AuNC@GSH solution. Subsequently, a reliable AuNC@GSH/MUA-based real-time assay of acid phosphatase (ACP) is established for the first time, inspired by the selective coordination of Fe3+ with surface ligands of AuNCs, the higher binding affinity between the pyrophosphate ion (PPi) and Fe3+, and the hydrolysis of PPi into orthophosphate by ACP. Our fluorescent chemosensor can also be applied to assay ACP in a real biological sample and, furthermore, to screen the inhibitor of ACP. This report paves a new avenue for synthesizing AuNCs based on either the bottom-up reduction or top-down etching method, establishing real-time fluorescence assays for ACP by means of PPi as the substrate, and further exploring the sensing applications of fluorescent AuNCs.A novel and convenient one-pot but two-step synthesis of fluorescent gold nanoclusters, incorporating glutathione (GSH) and 11-mercaptoundecanoic acid (MUA) as the functionalized ligands (i.e. AuNCs@GSH/MUA), is demonstrated. Herein, the mixing of HAuCl4 and GSH in aqueous solution results in the immediate formation of non-fluorescent GSH-Au+ complexes, and then a class of ~2.6 nm GSH-coated AuNCs (AuNCs@GSH) with mild orange-yellow fluorescence after several days. Interestingly, the intense orange-red emitting ~1.7 nm AuNCs@GSH/MUA can be synthesized within seconds by

  3. Colorimetric Sugar Sensing Using Boronic Acid-Substituted Azobenzenes

    Directory of Open Access Journals (Sweden)

    Yuya Egawa

    2014-02-01

    Full Text Available In association with increasing diabetes prevalence, it is desirable to develop new glucose sensing systems with low cost, ease of use, high stability and good portability. Boronic acid is one of the potential candidates for a future alternative to enzyme-based glucose sensors. Boronic acid derivatives have been widely used for the sugar recognition motif, because boronic acids bind adjacent diols to form cyclic boronate esters. In order to develop colorimetric sugar sensors, boronic acid-conjugated azobenzenes have been synthesized. There are several types of boronic acid azobenzenes, and their characteristics tend to rely on the substitute position of the boronic acid moiety. For example, o-substitution of boronic acid to the azo group gives the advantage of a significant color change upon sugar addition. Nitrogen-15 Nuclear Magnetic Resonance (NMR studies clearly show a signaling mechanism based on the formation and cleavage of the B–N dative bond between boronic acid and azo moieties in the dye. Some boronic acid-substituted azobenzenes were attached to a polymer or utilized for supramolecular chemistry to produce glucose-selective binding, in which two boronic acid moieties cooperatively bind one glucose molecule. In addition, boronic acid-substituted azobenzenes have been applied not only for glucose monitoring, but also for the sensing of glycated hemoglobin and dopamine.

  4. MRI probes for sensing biologically relevant metal ions.

    Science.gov (United States)

    Bonnet, Célia S; Tóth, Eva

    2010-03-01

    Given the important role of metal ions in fundamental biological processes, the visualization of their concentration in living animals by repeatable, noninvasive imaging techniques, such as MRI, would be highly desirable. A large number of metal-responsive MRI contrast agents, the majority based on Gd(3+) complexes, have been reported in recent years. The contrast-enhancing properties (relaxivity) of a Gd(3+) complex can be most conveniently modulated by interaction with the sensed metal cation via changes in the number of water molecules bound directly to Gd(3+) or changes in the size of the complex, which represent the two major strategies to develop metal sensitive MRI probes. Here, we survey paramagnetic lanthanide complexes involving Gd(3+) agents and paramagnetic chemical exchange saturation transfer probes designed to detect the most important endogenous metal ions: calcium, zinc, iron and copper. Future work will likely focus on extending applications of these agents to living animals, as well as on exploring new ways of creating molecular MRI probes in order to meet requirements such as higher specificity or lower detection limits.

  5. Microbial Nucleic Acid Sensing in Oral and Systemic Diseases.

    Science.gov (United States)

    Crump, K E; Sahingur, S E

    2016-01-01

    One challenge in studying chronic infectious and inflammatory disorders is understanding how host pattern recognition receptors (PRRs), specifically toll-like receptors (TLRs), sense and respond to pathogen- or damage-associated molecular patterns, their communication with each other and different components of the immune system, and their role in propagating inflammatory stages of disease. The discovery of innate immune activation through nucleic acid recognition by intracellular PRRs such as endosomal TLRs (TLR3, TLR7, TLR8, and TLR9) and cytoplasmic proteins (absent in melanoma 2 and DNA-dependent activator of interferon regulatory factor) opened a new paradigm: Nucleic acid sensing is now implicated in multiple immune and inflammatory conditions (e.g., atherosclerosis, cancer), viral (e.g., human papillomavirus, herpes virus) and bacterial (e.g., Helicobacter pylori, pneumonia) diseases, and autoimmune disorders (e.g., systemic lupus erythematosus, rheumatoid arthritis). Clinical investigations reveal the overexpression of specific nucleic acid sensors in diseased tissues. In vivo animal models show enhanced disease progression associated with receptor activation. The involvement of nucleic acid sensors in various systemic conditions is further supported by studies reporting receptor knockout mice being either protected from or prone to disease. TLR9-mediated inflammation is also implicated in periodontal diseases. Considering that persistent inflammation in the oral cavity is associated with systemic diseases and that oral microbial DNA is isolated at distal sites, nucleic acid sensing may potentially be a link between oral and systemic diseases. In this review, we discuss recent advances in how intracellular PRRs respond to microbial nucleic acids and emerging views on the role of nucleic acid sensors in various systemic diseases. We also highlight new information on the role of intracellular PRRs in the pathogenesis of oral diseases including periodontitis

  6. Ion-exchange chromatographic analysis of peroxynitric acid.

    Science.gov (United States)

    Nakashima, Yoichi; Ikawa, Satoshi; Tani, Atsushi; Kitano, Katsuhisa

    2016-01-29

    Ion-exchange chromatographic analysis of peroxynitric acid (O2NOOH) was performed by combining an acidic eluate with an UV-vis detector and immersing the separation column in an ice-water bath. The decomposition behavior of peroxynitric acid in the solution was also studied using this system. The fraction for the peroxynitric acid peak was collected. Ion-exchange chromatographic analysis of this fraction, after standing at room temperature for 24h, showed that the decomposition products were mainly nitrate ions with a very small amount of nitrous acid. The peroxynitric acid peak area correlated perfectly with the total amount of decomposition products. The ion-exchange chromatographic isolation allowed us to evaluate the molar extinction coefficient of peroxynitric acid precisely in a wider wavelength range than previous reports. The value decreases monotonically from 1729±26M(-1)cm(-1) at 200nm to 12.0±0.5M(-1)cm(-1) at 290nm.

  7. 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 and... (.csml) Show Plasmacytoid dendritic cells: sensing nucleic acids in viral infection andautoimmune diseases.... PubmedID 18641647 Title Plasmacytoid dendritic cells: sensing nucleic acids in v

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

    Lifescience Database Archive (English)

    Full Text Available 17082566 Nucleic acid-sensing TLRs as modifiers of autoimmunity. Deane JA, Bolland ...S. J Immunol. 2006 Nov 15;177(10):6573-8. (.png) (.svg) (.html) (.csml) Show Nucleic acid-sensing TLRs as mo...difiers of autoimmunity. PubmedID 17082566 Title Nucleic acid-sensing TLRs as modifiers of autoimmunity. Aut

  9. The electron-transfer based interaction between transition metal ions and photoluminescent graphene quantum dots (GQDs): a platform for metal ion sensing.

    Science.gov (United States)

    Huang, Hongduan; Liao, Lei; Xu, Xiao; Zou, Mingjian; Liu, Feng; Li, Na

    2013-12-15

    The electron-transfer based quenching effect of commonly encountered transition metal ions on the photoluminescence of grapheme quantum dots (GQDs) was for the first time investigated, and was found to be associated with electron configuration of the individual metal ion. Ethylene diamine tetraacetic acid (EDTA), the metal ion chelator, can competitively interact with metal ions to recover the quenched photoluminescence of GQDs. Basically, metal ions with empty or completely filled d orbits could not quench the photoluminescence of GQDs, but this quenching effect was observed for the metal ions with partly filled d orbits. Based on the quenching-recovering strategy, a simple optical metal sensing platform was established by taking Ni(2+) as an example. Using the nickel ion-specific chelating reagent, dimethylglyoxime (DMG), to replace EDTA, a detection limit of 4.1 μM was obtained in standard solution. This proposed strategy does not need further functionalization of GQDs, facilitating the application for simple, fast and cost-effective screening of metal ions.

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

    International Nuclear Information System (INIS)

    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

  11. Ion sensing properties of vanadium/tungsten mixed oxides

    International Nuclear Information System (INIS)

    Vanadium/tungsten mixed oxide (V2O5/WO3) 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 V2O5 after the insertion of WO3 revealing that the lamellar structure is under compressive stress. The crystallinity increases with increasing WO3 molar ratio. The film is not homogeneous, with more WO3 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% WO3 molar ratio. For higher WO3 molar ratios, the behavior is not linear. It can be concluded that V2O5 dominates for acidic solutions while WO3 dominates for basic solutions. Therefore, the mixed oxide with low amount of WO3 is the main candidate for further use as biosensor.

  12. Ion sensing properties of vanadium/tungsten mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Guidelli, Eder Jose, E-mail: ederguidelli@gmail.com [Departamento de Fisica e Matematica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirao Preto, SP (Brazil); Guerra, Elidia Maria [Universidade Federal de Sao Joao Del Rei, CAP, Ouro Branco-MG (Brazil); Mulato, Marcelo [Departamento de Fisica e Matematica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirao Preto, SP (Brazil)

    2011-02-15

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

  13. Nucleic Acid Nanostructures for Chemical and Biological Sensing.

    Science.gov (United States)

    Chandrasekaran, Arun Richard; Wady, Heitham; Subramanian, Hari K K

    2016-05-01

    The nanoscale features of DNA have made it a useful molecule for bottom-up construction of nanomaterials, for example, two- and three-dimensional lattices, nanomachines, and nanodevices. One of the emerging applications of such DNA-based nanostructures is in chemical and biological sensing, where they have proven to be cost-effective, sensitive and have shown promise as point-of-care diagnostic tools. DNA is an ideal molecule for sensing not only because of its specificity but also because it is robust and can function under a broad range of biologically relevant temperatures and conditions. DNA nanostructure-based sensors provide biocompatibility and highly specific detection based on the molecular recognition properties of DNA. They can be used for the detection of single nucleotide polymorphism and to sense pH both in solution and in cells. They have also been used to detect clinically relevant tumor biomarkers. In this review, recent advances in DNA-based biosensors for pH, nucleic acids, tumor biomarkers and cancer cell detection are introduced. Some challenges that lie ahead for such biosensors to effectively compete with established technologies are also discussed. PMID:27040036

  14. The polarographic electroreduction of uranyl ion in arsenic acid solution

    International Nuclear Information System (INIS)

    The electroreduction of uranyl ion in arsenic acid studied by d.c. polarography shows one reduction wave at all the used arsenic acid concentrations corresponding to one electron reduction mechanism. At low arsenic acid concentration (0,1 - 0,3 M)UO2(ClO4)2 is reduced to HUO2AsO4. At higher acid concentration (0,6 M) the HUO2AsO4 molecules are reduced to UO2+ (pentavalent uranium). It is also reliable to study polarographic behaviour of uranyl ions in arsenic acid solutions up to pH 3,01. It is also possible to apply this method for the analytical determination of uranyl ion concentrations up to 2 mM. (Author)

  15. Reproducible Design for the Optical Screening and Sensing of Hg(II Ions

    Directory of Open Access Journals (Sweden)

    Emad A. Elshehy

    2014-10-01

    Full Text Available We fabricated silica nanotubes with hexagonally ordered mesopores (6 nm inside a membrane disc with a uniform channel neck size of 200 nm and a longitudinal thickness of 60 μm to design an optical sensor membrane (OSM for the screening and sensing of extremely toxic Hg(II ions. The optical detection and quantitative recognition of Hg(II ions in water were conducted even at trace concentrations without the need for sophisticated instruments. The OSM design was based on the physical interaction of a responsive organic probe with silica pore surfaces followed by strong and selective binding Hg(II–probe interactions under specific sensing conditions, particularly at pH 5. Ultra-trace concentrations of Hg(II ions were easily detected with the naked eye using the OSM. The remarkable ion spectral response of Hg(II ion–OSM ensured the excellent quantification of the OSM for Hg(II ion sensing over a wide range of concentrations with a detection limit of 1.75 × 10−9 M. This result indicated that low concentrations of Hg(II ions can be detected with a high sensitivity. One of the key issues of OSM is the Hg(II ion-selective workability even in the presence of high doses of competitive matrices and species. The OSM design showed significant Hg(II ion-sensing capability despite the number of reuse/recycles using simple decomplexation. Given its high selectivity, fast response, and sensitivity, the OSM could be developed into a specific Hg(II ion-sensing kit in aqueous solutions.

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

    International Nuclear Information System (INIS)

    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

  17. Nanoliter-scale, regenerable ion sensor: sensing with surface functionalized microstructured optical fiber

    Science.gov (United States)

    Heng, Sabrina; Nguyen, Mai-Chi; Kostecki, Roman; Monro, Tanya M.; Abell, Andrew D.

    2013-05-01

    The first nanoliter-scale regenerable ion sensor based on microstructured optical fiber (MOF) is reported. The air holes of the MOF are functionalized with a monoazacrown bearing spiropyran to give a switchable sensor that detects lithium ions down to 100 nM in nanoliter-scale volumes. Ion binding is turned on and off on upon irradiation with light, with the sensor being unaffected by multiple rounds of photoswitching. Unbound ions are flushed from the fiber in the `off' state to allow the sensor to be reused. The integration of an ionophore into the sensor paves the way for the development of highly specific light-based sensing platforms that are readily adaptable to sense a particular ion simply by altering the ionophore design.

  18. 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.

  19. Ion-beam assisted laser fabrication of sensing plasmonic nanostructures

    CERN Document Server

    Kuchmizhak, Aleksandr; Vitrik, Oleg; Kulchin, Yuri; Milichko, Valentin; Makarov, Sergey; Kudryashov, Sergey

    2015-01-01

    Simple high-performance two-stage hybrid technique was developed for fabrication of different plasmonic nanostructures, including nanorods, nanorings, as well as more complex structures on glass substrates. In this technique a thin noble metal film on a dielectric substrate is irradiated by a tightly focused single nanosecond laser pulse and then the modified region is slowly polished by an accelerated argon ion (Ar+) beam. As a result, each nanosecond laser pulse locally modifies the initial metal film through initiation of fast melting and subsequent hydrodynamic processes, while the following Ar+-ion polishing removes the rest of the film, revealing the hidden topography features and fabricating separate plasmonic structures on the glass substrate. We demonstrate that the shape and lateral size of the resulting functional plasmonic nanostructures depends on the laser pulse energy and metal film thickness, while subsequent Ar+-ion polishing enables to vary height of the resulting nanostructures. The plasmon...

  20. Electrochemical, optical and metal ion sensing properties of dithizone derivatised electrodes

    CERN Document Server

    Mirkhalaf, F

    1998-01-01

    studied. Possible applications of these modified electrodes with potential control in metal ion detection are described. The electrochemical and SPR responses for the metal ion sensing by the monolayer films were compared with those of polymer films containing the same ligand. Derivatisation of electrode surfaces with ultra-thin films of organic molecules has been extensively studied for many applications in recent years. The present study is based on a new approach in the preparation and use of these electrodes for metal ion sensing. Modification of electrode surfaces with a ligand specific to heavy metal ions has been described. A new derivative of dithizone (DDz) and its secondary metal complexes have been synthesised and attached onto indium tin oxide (ITO) and gold electrodes. This was achieved by covalent bonding between carboxyl groups in DDz and terminal amine groups of molecules self-assembled on the electrode surfaces. These monolayer films were characterised by cyclic voltammetry, by in situ and ex...

  1. Gasotransmitter regulation of ion channels: a key step in O2 sensing by the carotid body.

    Science.gov (United States)

    Prabhakar, Nanduri R; Peers, Chris

    2014-01-01

    Carotid bodies detect hypoxia in arterial blood, translating this stimulus into physiological responses via the CNS. It is long established that ion channels are critical to this process. More recent evidence indicates that gasotransmitters exert powerful influences on O2 sensing by the carotid body. Here, we review current understanding of hypoxia-dependent production of gasotransmitters, how they regulate ion channels in the carotid body, and how this impacts carotid body function.

  2. Ratiometric optical fiber sensor for dual sensing of copper ion and dissolved oxygen.

    Science.gov (United States)

    Chu, Cheng-Shane; Chuang, Chih-Yung

    2015-12-20

    This paper develops a new ratiometric optical dual sensor for Cu2+ ions and dissolved oxygen (DO) incorporating a sol-gel matrix doped with palladium tetrakis pentafluorophenyl porphine as the oxygen-sensitive material, CdSe quantum dots as the Cu2+ ion-sensing material, and 7-amino-4-trifluoromethyl coumarin as the Cu2+ /DO practically independent fluorescent dye. The feasibility of coating an optical fiber with the sensing film to fabricate a ratiometric optical fiber dual sensor is investigated. Using an LED with a central wavelength of 405 nm as an excitation source, it is shown that the emission wavelengths of the Cu2+ ion-sensitive, DO-sensitive dye and the reference dye have no spectral overlap and therefore permit Cu2+ ion and DO concentration to be measured using a ratiometric-based method. The ratiometric optical fiber dual sensor has been tested with regard to monitoring different Cu2+ ion (0-10 μM) and DO concentrations (0-38 mg/L). The results show that the luminescence properties of the Cu2+ ion sensor are independent of the presence of the oxygen sensor and have a uniquely good linear response in the 0-10 μM range. The proposed ratiometric sensing approach presented in this study has the advantage of suppressing spurious fluctuations in the intensity of the excitation source. PMID:26837033

  3. 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

  4. Precipitation of humic acid with divalent ions

    DEFF Research Database (Denmark)

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

    2001-01-01

    HA concentration. With respect to region III, it is not exclusively determined whether precipitation is caused by HA behaving as a polyelectrolyte or possessing colloidal properties. The general observation throughout is that HA appears to behave as a polyelectrolyte at low concentrations......The aim of this study is to investigate precipitation proper-ties of humic acid (HA). This is done by studying a commercial available humic acid salt (HA) from which a phase diagram is established by adding various amounts of BaCl2 to different concentrations of HA at pH 5.5. The phase diagram...... shows tree characteristic regions with markedly different precipitation courses: region I at HA concentration below 0.15g/l, region H at HA concentration between 0.15 and similar to2g/l and rgeion IV at HA concentration above 3.5g/l. Furthermore, a forth intermediate region M is observed between similar...

  5. Ion-Sensitive Field-Effect Transistor for Biological Sensing

    Directory of Open Access Journals (Sweden)

    Chang-Soo Lee

    2009-09-01

    Full Text Available In recent years there has been great progress in applying FET-type biosensors for highly sensitive biological detection. Among them, the ISFET (ion-sensitive field-effect transistor is one of the most intriguing approaches in electrical biosensing technology. Here, we review some of the main advances in this field over the past few years, explore its application prospects, and discuss the main issues, approaches, and challenges, with the aim of stimulating a broader interest in developing ISFET-based biosensors and extending their applications for reliable and sensitive analysis of various biomolecules such as DNA, proteins, enzymes, and cells.

  6. Fluorescent copper nanoparticles: recent advances in synthesis and applications for sensing metal ions

    Science.gov (United States)

    Guo, Yongming; Cao, Fengpu; Lei, Xiaoling; Mang, Lianghong; Cheng, Shengjuan; Song, Jintong

    2016-02-01

    Fluorescent copper nanoparticles (F-CuNPs) have received great attention due to their attractive features, such as water solubility, wide availability, ease of functionalization and good biocompatibility, and considerable efforts have been devoted to the preparation and applications of F-CuNPs. This review article comprises three main parts. In the first part, we briefly present the fluorescence properties of F-CuNPs. Then we cover the fabrication strategies of various F-CuNPs functionalized by different ligands. In the third part, we focus on the applications of F-CuNPs for sensing metal ions, including Hg2+, Pb2+, Cu2+, Fe3+ and other metal ions. Lastly, we further discuss the opportunities and challenges of F-CuNPs in the synthetic strategies and applications for sensing metal ions.

  7. Electrochemical Sensing and Imaging Based on Ion Transfer at Liquid/Liquid Interfaces

    Science.gov (United States)

    Amemiya, Shigeru; Kim, Jiyeon; Izadyar, Anahita; Kabagambe, Benjamin; Shen, Mei; Ishimatsu, Ryoichi

    2013-01-01

    Here we review the recent applications of ion transfer (IT) at the interface between two immiscible electrolyte solutions (ITIES) for electrochemical sensing and imaging. In particular, we focus on the development and recent applications of the nanopipet-supported ITIES and double-polymer-modified electrode, which enable the dynamic electrochemical measurements of IT at nanoscopic and macroscopic ITIES, respectively. High-quality IT voltammograms are obtainable using either technique to quantitatively assess the kinetics and dynamic mechanism of IT at the ITIES. Nanopipet-supported ITIES serves as an amperometric tip for scanning electrochemical microscopy to allow for unprecedentedly high-resolution electrochemical imaging. Voltammetric ion sensing at double-polymer-modified electrodes offers high sensitivity and unique multiple-ion selectivity. The promising future applications of these dynamic approaches for bioanalysis and electrochemical imaging are also discussed. PMID:24363454

  8. Electrochemical Sensing and Imaging Based on Ion Transfer at Liquid/Liquid Interfaces.

    Science.gov (United States)

    Amemiya, Shigeru; Kim, Jiyeon; Izadyar, Anahita; Kabagambe, Benjamin; Shen, Mei; Ishimatsu, Ryoichi

    2013-11-01

    Here we review the recent applications of ion transfer (IT) at the interface between two immiscible electrolyte solutions (ITIES) for electrochemical sensing and imaging. In particular, we focus on the development and recent applications of the nanopipet-supported ITIES and double-polymer-modified electrode, which enable the dynamic electrochemical measurements of IT at nanoscopic and macroscopic ITIES, respectively. High-quality IT voltammograms are obtainable using either technique to quantitatively assess the kinetics and dynamic mechanism of IT at the ITIES. Nanopipet-supported ITIES serves as an amperometric tip for scanning electrochemical microscopy to allow for unprecedentedly high-resolution electrochemical imaging. Voltammetric ion sensing at double-polymer-modified electrodes offers high sensitivity and unique multiple-ion selectivity. The promising future applications of these dynamic approaches for bioanalysis and electrochemical imaging are also discussed.

  9. 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.

  10. 18-Crown[6]ether functionalized reduced graphene oxide for membrane-free ion selective sensing

    DEFF Research Database (Denmark)

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    + , with a detection limit of 10-5 M without inference from other ions (Na+ , Li+ , NH4+ and Ca2+) in concentrations up to 2.5 × 10-2 M. Similar sensing was achieved with functionalized disposable SPE electrodes. The results demonstrate that RGO-crown[6] is a conductive material full of promise for application......The focus of this work is on the synthesis of a 1-Aza-18-crown[6]ether functionalized reduced graphene oxide (RGO-crown[6]) with specific K+ binding sites on the RGO surface. Glassy carbon electrodes (GCE) functionalized with RGO-crown[6] weretested for selective potentiometric sensing of K...

  11. Sensing behavior and logic operation of a colorimetric fluorescence sensor for Hg2 +/Cu2 + ions

    Science.gov (United States)

    He, Tian; Lin, Cuiling; Gu, Zhengye; Xu, Luonan; Yang, Anle; Liu, Yuanyuan; Fang, Huajun; Qiu, Huayu; Zhang, Jing; Yin, Shouchun

    2016-10-01

    A BODIPY-based 1 as a colorimetric fluorescence sensor was synthesized, and its metal sensing property was investigated. 1 displayed high selectivity and sensitivity towards Hg2 + and Cu2 + ions among 15 different metal cations. The addition of Hg2 + and Cu2 + ions into 1 in CH3CN resulted in a significant bathochromic shift of the UV absorption spectra from 533 nm to 560 nm and 593 nm, respectively, changing the corresponding colors from pink to purple and blue. When excited at 530 nm, the fluorescence intensity of 1 was quenched over 75% upon addition of Hg2 + ions, while 1 with Cu2 + ions exhibited significant fluorescence enhancement with a 23 nm red-shift. Based on these results, three logic gates (OR, IMPLICATION, and INHIBIT) were obtained by controlling the chemical inputs.

  12. Sensing behavior and logic operation of a colorimetric fluorescence sensor for Hg(2+)/Cu(2+) ions.

    Science.gov (United States)

    He, Tian; Lin, Cuiling; Gu, Zhengye; Xu, Luonan; Yang, Anle; Liu, Yuanyuan; Fang, Huajun; Qiu, Huayu; Zhang, Jing; Yin, Shouchun

    2016-10-01

    A BODIPY-based 1 as a colorimetric fluorescence sensor was synthesized, and its metal sensing property was investigated. 1 displayed high selectivity and sensitivity towards Hg(2+) and Cu(2+) ions among 15 different metal cations. The addition of Hg(2+) and Cu(2+) ions into 1 in CH3CN resulted in a significant bathochromic shift of the UV absorption spectra from 533nm to 560nm and 593nm, respectively, changing the corresponding colors from pink to purple and blue. When excited at 530nm, the fluorescence intensity of 1 was quenched over 75% upon addition of Hg(2+) ions, while 1 with Cu(2+) ions exhibited significant fluorescence enhancement with a 23nm red-shift. Based on these results, three logic gates (OR, IMPLICATION, and INHIBIT) were obtained by controlling the chemical inputs. PMID:27239948

  13. Catalytic protection of stannous ion by ascorbic acid in diphosphonic acids solutions

    Institute of Scientific and Technical Information of China (English)

    LiuGuo-Zheng; LiuFei; 等

    1998-01-01

    The protective ability of ascorbic acid(Vc) on stannous ion and the influence of light irradiation on the stability of stannous ion in diphosphonate medium at pH=5 have been examined in order to attain minimal loss of stannous ion during the production of lyophilized radiopharmaceutical kits.The sum of stanous ion and Vc was determined with iodometric method.It was shown that the protective ability of Vc was still strong at Vc concentration much lower than that of stannous ion and the illumination by fluorescent lamp was unfavorable to the stability of stannous ion.The change of pH in the range 3-9 did not affect the action of Vc significantly.

  14. Screen-printed back-to-back electroanalytical sensors: heavy metal ion sensing.

    Science.gov (United States)

    Ruas de Souza, Ana P; Foster, Christopher W; Kolliopoulos, Athanasios V; Bertotti, Mauro; Banks, Craig E

    2015-06-21

    Screen-printed back-to-back microband electroanalytical sensors are applied to the quantification of lead(II) ions for the first time. In this configuration the electrodes are positioned back-to-back with a common electrical connection to the two working electrodes with the counter and reference electrodes for each connected in the same manner as a normal "traditional" screen-printed sensor. Proof-of-concept is demonstrated for the electroanalytical sensing of lead(II) ions utilising square-wave anodic stripping voltammetry where an increase in the electroanalytical sensitivity is observed by a factor of 5 with the back-to-back microband configuration at a fixed lead(II) ion concentration of 5 μg L(-1) utilising a deposition potential and time of -1.2 V and 30 seconds respectively, compared to a conventional (single) microband electrode. The back-to-back microband configuration allows for the sensing of lead(II) ions with a linear range from 5 to 110 μg L(-1) with a limit of detection (based on 3σ) corresponding to 3.7 μg L(-1). The back-to-back microband configuration is demonstrated to quantify the levels of lead(II) ions within drinking water corresponding to a level of 2.8 (±0.3) μg L(-1). Independent validation was performed using ICP-OES with the levels of lead(II) ions found to correspond to 2.5 (±0.1) μg L(-1); the excellent agreement between the two methods validates the electroanalytical procedure for the quantification of lead(II) ions in drinking water. This back-to-back configuration exhibits an excellent validated analytical performance for the determination of lead(II) ions within drinking water at World Health Organisation levels (limited to 10 μg L(-1) within drinking water). PMID:25902942

  15. Screen-printed back-to-back electroanalytical sensors: heavy metal ion sensing.

    Science.gov (United States)

    Ruas de Souza, Ana P; Foster, Christopher W; Kolliopoulos, Athanasios V; Bertotti, Mauro; Banks, Craig E

    2015-06-21

    Screen-printed back-to-back microband electroanalytical sensors are applied to the quantification of lead(II) ions for the first time. In this configuration the electrodes are positioned back-to-back with a common electrical connection to the two working electrodes with the counter and reference electrodes for each connected in the same manner as a normal "traditional" screen-printed sensor. Proof-of-concept is demonstrated for the electroanalytical sensing of lead(II) ions utilising square-wave anodic stripping voltammetry where an increase in the electroanalytical sensitivity is observed by a factor of 5 with the back-to-back microband configuration at a fixed lead(II) ion concentration of 5 μg L(-1) utilising a deposition potential and time of -1.2 V and 30 seconds respectively, compared to a conventional (single) microband electrode. The back-to-back microband configuration allows for the sensing of lead(II) ions with a linear range from 5 to 110 μg L(-1) with a limit of detection (based on 3σ) corresponding to 3.7 μg L(-1). The back-to-back microband configuration is demonstrated to quantify the levels of lead(II) ions within drinking water corresponding to a level of 2.8 (±0.3) μg L(-1). Independent validation was performed using ICP-OES with the levels of lead(II) ions found to correspond to 2.5 (±0.1) μg L(-1); the excellent agreement between the two methods validates the electroanalytical procedure for the quantification of lead(II) ions in drinking water. This back-to-back configuration exhibits an excellent validated analytical performance for the determination of lead(II) ions within drinking water at World Health Organisation levels (limited to 10 μg L(-1) within drinking water).

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

    International Nuclear Information System (INIS)

    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.

  17. 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...... ions, rubidium ions and caesium ions....

  18. Colorimetric and fluorescent sensing of transition metal ions in aqueous medium by salicylaldimine based chemosensor

    International Nuclear Information System (INIS)

    The cation sensing property of highly sensitive chromogenic receptor N, N′-bis (salicylidine)-o-phenylene diamine (receptor 1) was studied by visual observation, UV–vis spectroscopy and fluorescence spectroscopy. The proposed study has been targeted to sense the first transition series metal cations like Fe3+, Co2+, Ni2+ and Cu2+. Binding affinity toward Cu2+ is found to be of higher magnitude compared to the other three cations mentioned. Receptor 1 on binding with Fe3+, Co2+ Ni2+ and Cu2+ ions shows fluorescence enhancement which is due to the inhibition of PET mechanism. - Graphical abstract: The cation sensing property of highly sensitive chromogenic receptor N, N′-bis (salicylidine)-o-phenylene diamine was studied by naked eye observation, UV–vis spectroscopy and fluorescence spectroscopy. The proposed study has been targeted to sense the first transition series metal cations like Fe3+, Co2+, Ni2+ and Cu2+. Binding affinity toward Cu2+ is found to be of higher magnitude compared to the other three cations mentioned. Receptor 1 on binding with Fe3+, Co2+ Ni2+ and Cu2+ ions shows fluorescence enhancement which is due to the inhibition of PET mechanism. Highlights: ► Receptor 1 serves as a multi channel probe for different transition metal cations. ► Binding constant for Cu2+ is of higher magnitude compared to the other cations. ► The ions bind to the receptor through NONO centers forming 2:1 and 1:1 complexes. ► Paramagnetic ions show fluorescent enhancement due to the inhibition of PET mechanism.

  19. 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.

  20. Cross-Reactive Sensor Array for Metal Ion Sensing Based on Fluorescent SAMs

    Directory of Open Access Journals (Sweden)

    Mercedes Crego-Calama

    2007-09-01

    Full Text Available Fluorescent self assembled monolayers (SAMs on glass were previouslydeveloped in our group as new sensing materials for metal ions. These fluorescent SAMs arecomprised by fluorophores and small molecules sequentially deposited on a monolayer onglass. The preorganization provided by the surface avoids the need for complex receptordesign, allowing for a combinatorial approach to sensing systems based on small molecules.Now we show the fabrication of an effective microarray for the screening of metal ions andthe properties of the sensing SAMs. A collection of fluorescent sensing SAMs wasgenerated by combinatorial methods and immobilized on the glass surfaces of a custom-made 140 well microtiter-plate. The resulting libraries are easily measured and show variedresponses to a series cations such as Cu2+ , Co2+ , Pb2+ , Ca2+ and Zn2+ . These surfaces are notdesigned to complex selectively a unique analyte but rather they are intended to producefingerprint type responses to a range of analytes by less specific interactions. The unselectiveresponses of the library to the presence of different cations generate a characteristic patternfor each analyte, a “finger print” response.

  1. Cross-Reactive Sensor Array for Metal Ion Sensing Based on Fluorescent SAMs

    Science.gov (United States)

    Basabe-Desmonts, Lourdes; van der Baan, Frederieke; Zimmerman, Rebecca S.; Reinhoudt, David N.; Crego-Calama, Mercedes

    2007-01-01

    Fluorescent self assembled monolayers (SAMs) on glass were previously developed in our group as new sensing materials for metal ions. These fluorescent SAMs are comprised by fluorophores and small molecules sequentially deposited on a monolayer on glass. The preorganization provided by the surface avoids the need for complex receptor design, allowing for a combinatorial approach to sensing systems based on small molecules. Now we show the fabrication of an effective microarray for the screening of metal ions and the properties of the sensing SAMs. A collection of fluorescent sensing SAMs was generated by combinatorial methods and immobilized on the glass surfaces of a custom-made 140 well microtiter-plate. The resulting libraries are easily measured and show varied responses to a series cations such as Cu2+, Co2+, Pb2+, Ca2+ and Zn2+. These surfaces are not designed to complex selectively a unique analyte but rather they are intended to produce fingerprint type responses to a range of analytes by less specific interactions. The unselective responses of the library to the presence of different cations generate a characteristic pattern for each analyte, a “finger print” response.

  2. Ion-sensitive field effect transistors for pH and potassium ion concentration sensing: towards detection of myocardial ischemia

    Science.gov (United States)

    Rai, Pratyush; Jung, Soyoun; Ji, Taeksoo; Varadan, Vijay K.

    2008-03-01

    Ion Sensitive Field Effect Transistors (ISFETs) for sensing change in ionic concentration in biological systems can be used for detecting critical conditions like Myocardial Ischemia. Having the ability to yield steady signal characteristics can be used to observe the ionic concentration gradients which mark the onset of ischemia. Two ionic concentrations, pH and [K +], have been considered as the indicator for Myocardial Ischemia in this study. The ISFETs in this study have an organic semi-conductor film as the electronically active component. Poly-3 hexylthiophene was chosen for its compatibility to the solution processing, which is a simple and economical method of thin film fabrication. The gate electrode, which regulates the current in the active layer, has been employed as the sensor element. The devices under study here were fabricated on a flexible substrate PEN. The pH sensor was designed with the Tantalum Oxide gate dielectric as the ion selective component. The charge accumulated on the surface of the metal oxide acts as the source of the effecter electric field. The device was tested for pH values between 6.5 and 7.5, which comprises the variation observed during ischemic attack. The potassium ion sensor has got a floating gate electrode which is functionalized to be selective to potassium ion. The device was tested for potassium ion concentration between 5 and 25 mM, which constitutes the variation in extra cellular potassium ion concentration during ischemic attack. The device incorporated a monolayer of Valinomycin, a potassium specific ionophore, on top of the gate electrode.

  3. DMPD: Nucleic acid-sensing Toll-like receptors: beyond ligand search. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 18321608 Nucleic acid-sensing Toll-like receptors: beyond ligand search. Miyake K. ...Adv Drug Deliv Rev. 2008 Apr 29;60(7):782-5. Epub 2008 Feb 15. (.png) (.svg) (.html) (.csml) Show Nucleic ac...id-sensing Toll-like receptors: beyond ligand search. PubmedID 18321608 Title Nucleic acid-sensing Toll-like

  4. The bile acid-sensitive ion channel (BASIC), the ignored cousin of ASICs and ENaC.

    Science.gov (United States)

    Wiemuth, Dominik; Assmann, Marc; Gründer, Stefan

    2014-01-01

    The DEG/ENaC gene family of ion channels is characterized by a high degree of structural similarity and an equally high degree of diversity concerning the physiological function. In humans and rodents, the DEG/ENaC family comprises 2 main subgroups: the subunits of the epithelial Na(+) channel (ENaC) and the subunits of the acid sensing ion channels (ASICs). The bile acid-sensitive channel (BASIC), previously known as BLINaC or INaC, represents a third subgroup within the DEG/ENaC family. Although BASIC was identified more than a decade ago, very little is known about its physiological function. Recent progress in the characterization of this neglected member of the DEG/ENaC family, which is summarized in this focused review, includes the discovery of surprising species differences, its pharmacological characterization, and the identification of bile acids as putative natural activators.

  5. Recognition of pathogen-associated nucleic acids by endosomal nucleic acid-sensing toll-like receptors

    Institute of Scientific and Technical Information of China (English)

    Xiaobing He; Huaijie Jia; Zhizhong Jing; Dingxiang Liu

    2013-01-01

    Foreign nucleic acids,the essential signature molecules of invading pathogens that act as danger signals for host cells,are detected by endosomal nucleic acid-sensing tolllike receptors (TLRs) 3,7,8,9,and 13.These TLRs have evolved to recognize ‘non-self' nucleic acids within endosomal compartments and rapidly initiate innate immune responses to ensure host protection through induction of type Ⅰ interferons,inflammatory cytokines,chemokines,and co-stimulatory molecules and maturation of immune cells.In this review,we highlight our understanding of the recognition of pathogen-associated nucleic acids and activation of corresponding signaling pathways through endosomal nucleic acid-sensing TLRs 3,7,8,9,and 13 for an enormous diversity of pathogens,with particular emphasis on their compartmentalization,intracellular trafficking,proteolytic cleavage,autophagy,and regulatory programs.

  6. 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%.

  7. 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.

  8. Non-Specific Zn2+ Ion Sensing Using Ultrasmall Gadolinium Oxide Nanoparticle as a Magnetic Resonance Imaging Contrast Agent.

    Science.gov (United States)

    Bony, Badrul Alam; Baeck, Jong Su; Chang, Yongmin; Lee, Gang Ho

    2016-03-01

    The gadolinium oxide (Gd2O3) nanoparticles are well-known potential candidates for a positive magnetic resonance imaging (MRI) contrast agent owing to their large longitudinal water proton relaxivity (r1) value with r2/r1 ratio close to one (r2 = transverse water proton relaxivity). In addition they may be used to sense metal ions because their r1 and r2 values can be altered in the presence of metal ions. This may allow us to study metabolic processes involving metal ions and to diagnose disease related to abnormal concentrations of metal ions in the body in a non-invasive way. In this study ultrasmall Gd2O3 nanoparticles were for the first time applied to non-specifically sense Zn2+ ions in aqueous solution. We explored this by measuring r1 and r2 values in the presence of Zn2+ ions in solution.

  9. Acidic Tumor Microenvironment and pH-Sensing G protein-Coupled Receptors

    Directory of Open Access Journals (Sweden)

    Calvin R. Justus

    2013-12-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2013-01-01

    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. PMID:24367336

  11. Lichen secondary metabolite evernic acid as potential quorum sensing inhibitor against Pseudomonas aeruginosa.

    Science.gov (United States)

    Gökalsın, Barış; Sesal, Nüzhet Cenk

    2016-09-01

    Cystic Fibrosis is a genetic disease and it affects the respiratory and digestive systems. Pseudomonas aeruginosa infections in Cystic Fibrosis are presented as the main cause for high mortality and morbidity rates. Pseudomonas aeruginosa populations can regulate their virulence gene expressions via the bacterial communication system: quorum sensing. Inhibition of quorum sensing by employing quorum sensing inhibitors can leave the bacteria vulnerable. Therefore, determining natural sources to obtain potential quorum sensing inhibitors is essential. Lichens have ethnobotanical value for their medicinal properties and it is possible that their secondary metabolites have quorum sensing inhibitor properties. This study aims to investigate an alternative treatment approach by utilizing lichen secondary metabolite evernic acid to reduce the expressions of Pseudomonas aeruginosa virulence factors by inhibiting quorum sensing. For this purpose, fluorescent monitor strains were utilized for quorum sensing inhibitor screens and quantitative reverse-transcriptase PCR analyses were conducted for comparison. Results indicate that evernic acid is capable of inhibiting Pseudomonas aeruginosa quorum sensing systems. PMID:27465850

  12. Focused ion beam post-processing of optical fiber Fabry-Perot cavities for sensing applications.

    Science.gov (United States)

    André, Ricardo M; Pevec, Simon; Becker, Martin; Dellith, Jan; Rothhardt, Manfred; Marques, Manuel B; Donlagic, Denis; Bartelt, Hartmut; Frazão, Orlando

    2014-06-01

    Focused ion beam technology is combined with chemical etching of specifically designed fibers to create Fabry-Perot interferometers. Hydrofluoric acid is used to etch special fibers and create microwires with diameters of 15 μm. These microwires are then milled with a focused ion beam to create two different structures: an indented Fabry-Perot structure and a cantilever Fabry-Perot structure that are characterized in terms of temperature. The cantilever structure is also sensitive to vibrations and is capable of measuring frequencies in the range 1 Hz - 40 kHz.

  13. Gold nanoparticles with cyclic phenylazomethines: one-pot synthesis and metal ion sensing.

    Science.gov (United States)

    Shomura, Ryo; Chung, Keum Jee; Iwai, Hideo; Higuchi, Masayoshi

    2011-07-01

    New gold nanoparticles covered with cyclic phenylazomethine (CPA) were obtained by a one-pot synthesis. It is confirmed by XPS that imines of CPA in the nanoparticles (Au-CPA) are partially reduced to amines. The amine part of CPA in Au-CPA is attached to the surfaces of gold nanoparticles, and the imine part works as a redox-active site. A glassy carbon electrode modified with Au-CPA was revealed to work as an electrochemical probe for metal ion sensing.

  14. Functionalization of exposed core fibers with multiligand binding molecules for fluorescence based ion sensing

    Science.gov (United States)

    Kostecki, Roman; Heng, Sabrina; Ebendorff-Heidepriem, Heike; Abell, Andrew D.; Monro, Tanya M.

    2014-05-01

    The results of functionalizing exposed-core optical fiber with multiligand binding sensor molecules for ion detection is presented. We show that the capacity of the sensor molecules to bind multiple ligands is negated when the sensor molecules are covalently bound, making the method ineffective where multiligand binding fluoroionophores are needed. An alternate functionalization method using thin film polymer doped with multiligand binding fluoroionophores is shown, demonstrating the ability for ion detection in a case where multiligand binding is needed. This one step functionalizing process for optical fiber sensing applications does not require surface attachment functional groups and has the potential to be inline with fiber drawing so that long lengths of functionalized fiber can be fabricated.

  15. Carbon Dot Based Sensing of Dopamine and Ascorbic Acid

    Directory of Open Access Journals (Sweden)

    Upama Baruah

    2014-01-01

    Full Text Available We demonstrate carbon dot based sensor of catecholamine, namely, dopamine and ascorbic acid. Carbon dots (CDs were prepared from a green source: commercially available Assam tea. The carbon dots prepared from tea had particle sizes of ∼0.8 nm and are fluorescent. Fluorescence of the carbon dots was found to be quenched in the presence of dopamine and ascorbic acid with greater sensitivity for dopamine. The minimum detectable limits were determined to be 33 μM and 98 μM for dopamine and ascorbic acid, respectively. The quenching constants determined from Stern-Volmer plot were determined to be 5 × 10−4 and 1 × 10−4 for dopamine and ascorbic acid, respectively. A probable mechanism of quenching has been discussed in the paper.

  16. Recent Advances in Fluorescent Arylboronic Acids for Glucose Sensing

    OpenAIRE

    Jon Stefan Hansen; Jørn Bolstad Christensen

    2013-01-01

    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 aryl...

  17. Thermodynamics of Ion Pair Formations Between Charged Poly(Amino Acid)s.

    Science.gov (United States)

    Petrauskas, Vytautas; Maximowitsch, Eglė; Matulis, Daumantas

    2015-09-17

    Electrostatic interactions between the positively and negatively charged amino acids in proteins play an important role in macromolecular stability, binding, and recognition. Numerous amino acids in proteins are ionizable and may exist in negatively (e.g., Glu, Asp, Cys, Tyr) or positively (e.g., Arg, Lys, His, Orn) charged form dependent on pH and their pKas. In this work, isothermal titration calorimetry was used to determine the average standard values of thermodynamic parameters (the Gibbs free energy, enthalpy, entropy, and the heat capacity) of interaction between the positively charged amino acid homopolymers (polyarginine, polylysine, and polyornithine) and the negatively charged homopolymers (polyaspartic and polyglutamic acids). These values are of potential use in the computational models of interacting proteins and other biological macromolecules. The study showed that oppositely charged poly(amino acid)s bound each other with the stoichiometry of one positive to one negative charge. Arginine bound to the negatively charged amino acids with exothermic enthalpy and higher affinity than lysine. This result also suggests that positive charges in proteins should not be considered entirely equivalent if carried by lysine or arginine. The difference in binding energy of arginine and lysine association with the negatively charged amino acids was attributed to the enthalpy of the second ionic hydrogen bond formation between the guanidine and carboxylic groups. Despite the favorable enthalpic contribution, all such ion pair formation reactions were largely entropy-driven. Consistent with previously observed ionic interactions, the positive heat capacity was always observed during the amino acid ion pair formation.

  18. Direct ion speciation analysis with ion-selective membranes operated in a sequential potentiometric/time resolved chronopotentiometric sensing mode.

    Science.gov (United States)

    Ghahraman Afshar, Majid; Crespo, Gastón A; Bakker, Eric

    2012-10-16

    Ion-selective membranes based on porous polypropylene membranes doped with an ionophore and a lipophilic cation-exchanger are used here in a new tandem measurement mode that combines dynamic electrochemistry and zero current potentiometry into a single protocol. Open circuit potential measurements yield near-nernstian response slopes in complete analogy to established ion-selective electrode methodology. Such measurements are well established to give direct information on the so-called free ion concentration (strictly, activity) in the sample. The same membrane is here also operated in a constant current mode, in which the localized ion depletion at a transition time is visualized by chronopotentiometry. This dynamic electrochemistry methodology gives information on the labile ion concentration in the sample. The sequential protocol is established on potassium and calcium ion-selective membranes. An increase of the ionophore concentration in the membrane to 180 mM makes it possible to determine calcium concentrations as high as 3 mM by chronopotentiometry, thereby making it possible to directly detect total calcium in undiluted blood samples. Recovery times after current perturbation depend on the current amplitude but can be kept to below 1 min for the polypropylene based ion-selective membranes studied here. Plasticized PVC as membrane material is less suited for this protocol, especially when the measurement at elevated concentrations is desired. An analysis of current amplitudes, transition times, and concentrations shows that the data are described by the Sand equation and that migration effects are insignificant. A numerical model describes the experimental findings with good agreement and gives guidance on the required selectivity in order to observe a well-resolved transition time and on the expected errors due to insufficient selectivity. The simulations suggest that the methodology compares well to that of open circuit potentiometry, despite giving

  19. PDMS-based gold electrode for sensing ascorbic acid.

    Science.gov (United States)

    Xu, Qin; Bi, Lianhua; Zheng, Huxiang; Fan, Dahe; Wang, Wei

    2011-11-01

    Electrode with optical shapes is appreciated in microfluidics. In this article, we reported a flexible poly(dimethylsiloxane) (PDMS)-based gold electrode for ascorbic acid detection. Gold nanoparticles were chemically deposited on PDMS and the composite film was applied as working electrode. The electrode could undergo deformation and display good response performance without damage. This biosensor could give quick response to ascorbic acid (AA) (<5s) and the currents were linear with concentrations of AA in range of 0.023-7.00 mM and 30-100 mM, respectively. Limit of detection was 0.008 mM (S/N=3). This biosensor has been applied to determine ascorbic acid content in vitamin C tablets and the results were consistent with traditional iodometric method. PMID:21807485

  20. Carbon Dot Based Sensing of Dopamine and Ascorbic Acid

    OpenAIRE

    Upama Baruah; Neelam Gogoi; Achyut Konwar; Manash Jyoti Deka; Devasish Chowdhury; Gitanjali Majumdar

    2014-01-01

    We demonstrate carbon dot based sensor of catecholamine, namely, dopamine and ascorbic acid. Carbon dots (CDs) were prepared from a green source: commercially available Assam tea. The carbon dots prepared from tea had particle sizes of ∼0.8 nm and are fluorescent. Fluorescence of the carbon dots was found to be quenched in the presence of dopamine and ascorbic acid with greater sensitivity for dopamine. The minimum detectable limits were determined to be 33 μM and 98 μM for dopamine and ascor...

  1. INTERACTION OF AMINO ACID WITH ION EXCHANGE RESIN Ⅲ.FURTHER INVESTIGA TION OF SUPEREQUIVALENT ADSORPTION MECHANISM OF AMINO ACID ON ION EXCHANGE RESIN

    Institute of Scientific and Technical Information of China (English)

    ZHANGHui; SHAOTong; 等

    1994-01-01

    The adsorption isotherms of glycine,alanine and oxidized glutathion on strong acid cation and strong base anion exchange resins from aqueous solutions were measured and the superequivalent adsorptions of glycine and alanine observed.The infrared spectra of glycine adsorbed on the cation and the anion exchange resins,001×7 and 201×7,were measured.From these results,it is concluded that the amino acid adsorption on the ion exchange resin proceeds not only through ion exchange and proton transfer mechanisms,but also through aminecarboxylate interaction between the adsorbed amino acid molecules,and the formation of second layer of amino acid molecules is the mechanism of superequivalent adsorption of amino acid,the carboxylate or amine groups of the first layer of amino acid molecules on the ion exchange resin act as the exchange sites for the second layer of amino acid molecules.

  2. Bio-Sensing of Cadmium(II Ions Using Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Jindrich Kynicky

    2011-11-01

    Full Text Available Cadmium, as a hazardous pollutant commonly present in the living environment, represents an important risk to human health due to its undesirable effects (oxidative stress, changes in activities of many enzymes, interactions with biomolecules including DNA and RNA and consequent potential risk, making its detection very important. New and unique technological and biotechnological approaches for solving this problems are intensely sought. In this study, we used the commonly occurring potential pathogenic microorganism Staphylococcus aureus for the determination of markers which could be used for sensing of cadmium(II ions. We were focused on monitoring the effects of different cadmium(II ion concentrations (0, 1.25, 2.5, 5, 10, 15, 25 and 50 µg mL−1 on the growth and energetic metabolism of Staphylococcus aureus. Highly significant changes have been detected in the metabolism of thiol compounds—specifically the protein metallothionein (0.79–26.82 mmol/mg of protein, the enzyme glutathione S-transferase (190–5,827 µmol/min/mg of protein, and sulfhydryl groups (9.6–274.3 µmol cysteine/mg of protein. The ratio of reduced and oxidized glutathione indicated marked oxidative stress. In addition, dramatic changes in urease activity, which is connected with resistance of bacteria, were determined. Further, the effects of cadmium(II ions on the metabolic pathways of arginine, β-glucosidase, phosphatase, N-acetyl β-D-glucosamine, sucrose, trehalose, mannitol, maltose, lactose, fructose and total proteins were demonstrated. A metabolomic profile of Staphylococcus aureus under cadmium(II ion treatment conditions was completed seeking data about the possibility of cadmium(II ion accumulation in cells. The results demonstrate potential in the application of microorganisms as modern biosensor systems based on biological components.

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

    Science.gov (United States)

    Masek, Pavel; Keene, Alex C

    2013-01-01

    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.

  5. Conformational Transition of Poly (Acrylic Acid) Detected by Microcantilever Sensing

    Institute of Scientific and Technical Information of China (English)

    LI Kai; LIU Hong; ZHANG Qing-Chuan; XUE Chang-Guo; WU Xiao-Ping

    2007-01-01

    Poly (acrylic acid) (PAA) chains are grafted on one side of a microcantilever by the self-assembled method and the deflections of the microcantilever are detected as a function of medium pH from 3 to 11. It is found that when the pH varies, the microcantilever deflects because of the changing surface stress. By analysing the electrostatic repulsive effect, the surface stress change is related to the conformation transition of PAA from a collapse state to a swelling state. This method offers the interaction information among the polymer chains during the conformational transition and affords an alternative way to study conformational change of polymers.

  6. Dissociative CdSe/ZnS Quantum Dot-Molecule Complex for Luminescent Sensing of Metal Ions in Aqueous Solutions

    OpenAIRE

    Baranov, A. V.; Orlova, A. O.; Maslov, V. G.; Toporova, Yu. A.; Ushakova, E. V.; Federov, A.; Artemyev, M. V.; Perova, T. S.; Berwick, Kevin

    2010-01-01

    The optical properties of dissociative luminescent sensors based on a complex consisting of highly luminescent hydrophobic core/shell CdSe/ZnS quantum dots (QDs) and 1-(2-pyridilazo)-2-naphtol (PAN) molecules in organic solutions and a polymer film are reported. It is demonstrated, using Ni2+ and Co2+ ions as an illustrative example, that the QD/PAN sensor may have applications in the quantitative luminescent sensing of metal ions in aqueous solutions.

  7. Supercooling agent icilin blocks a warmth-sensing ion channel TRPV3.

    Science.gov (United States)

    Sherkheli, Muhammad Azhar; Gisselmann, Guenter; Hatt, Hanns

    2012-01-01

    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.

  8. 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.

  9. Extruded polymer films pigmented with a heterogeneous ion-pair based lumophore for O2 sensing.

    Science.gov (United States)

    Mills, Andrew; Graham, Ashleigh

    2013-11-01

    A novel approach to polymeric Ru(II)-diimine luminescent O2 sensors is described. The Ru(II)-diimine, tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) dichloride ([Ru(dpp)3](2+)), is first ion-paired to the surface of heterogeneous TiO2 particles, rendered negatively charged due to the alkali nature of the aqueous solution, to produce an O2 sensitive pigment with a strikingly high oxygen sensitivity (i.e. PO2 (S = 1/2) = 0.002 atm, where PO2 (S = 1/2) is defined as the amount of oxygen required to reduce the initial, oxygen free luminescence by 50%), and a rapid response to oxygen. The pigment is extruded in low density polyethylene (LDPE) to produce a thin (60 μm), flexible, O2 sensing plastic film, with an O2 sensitivity (PO2 (S = 1/2) = 0.84 atm) comparable to the more traditional homogeneous lumophore ion-pair based O2 sensor ink films reported in the literature. PMID:24040643

  10. 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.

  11. Effect of Ni7+ Ion Irradiation on Structure and Ammonia Sensing Properties of Thermally Oxidized Zinc and Indium Films

    Institute of Scientific and Technical Information of China (English)

    Amandeep Kaur Bal; Rafinder Singh; R.K. Bedi

    2012-01-01

    ZnO and In203 films were prepared by thermal oxidation of vacuum deposited zinc and indium films, respec- tively onto the glass substrate at 30 ℃. The fabricated films have been irradiated with 100-MeV Ni7+ ions at different fluences ranging from 5×1011 to 5×1013 ions/cm2. The structural and gas sensing properties of pristine and irradiated films have been discussed. X-ray diffraction (XRD) pattern of pristine and irradiated films reveal that the films are polycrystalline in nature and crystallinity increases after irradiation. In this study, highly porous In203 nanorods evolved when being irradiated at a fluence of 5×1013 ions/cm2 while ZnO film shows decrease in number of nanowires. The ammonia sensing performance of the Ni^7+ irradiated In203 films shows an improvement as compared to its pristine counterpart.

  12. Label-free and selective sensing of uric acid with gold nanoclusters as optical probe.

    Science.gov (United States)

    Wang, Jian; Chang, Yong; Wu, Wen Bi; Zhang, Pu; Lie, Shao Qing; Huang, Cheng Zhi

    2016-05-15

    Clinically, the amount of uric acid (UA) in biological fluids is closely related to some diseases such as hyperuricemia and gout, thus it is of great significance to sense UA in clinical samples. In this work, red gold nanoclusters (AuNCs) with relatively high fluorescence quantum yield and strong fluorescence emission were facilely available using bovine serum albumin (BSA) as template. The fluorescence of BSA-protected AuNCs can be sensitively quenched by H2O2, which is further capable of sensing UA through the specific catalytic oxidation with uricase, since it generates stoichiometric quantity of H2O2 by-product. The proposed assay allows for the selective detection of UA in the range of 10-800 μM with a detection limit of 6.6 μM, which is applicable to sense UA in clinical samples with satisfactory results, suggesting its great potential for diagnostic purposes. PMID:26992526

  13. Surface modified hydroxyapatite thick films for CO 2 gas sensing application: Effect of swift heavy ion irradiation

    Science.gov (United States)

    Mene, Ravindra U.; Mahabole, Megha P.; Khairnar, Rajendra S.

    2011-06-01

    Swift heavy ion irradiation (SHI) is used to modify the structural and gas sensing properties of Hydroxyapatite (HAp) thick films. The HAp thick films, prepared by screen printing technique, are irradiated with a variable fluence (3×10 10 to 3×10 13 ions/cm 2) of Ag 7+ ions of 100 MeV energy. XRD shows gradual change in crystallinity of the matrix with increase in ion fluence. Atomic force microscopy reveals the agglomeration of grains with pronounced cluster type structure at relatively higher ion fluence. For confirmation of efficient gas sensing of pristine and irradiated HAp thick films, repeatability and reproducibility tests are conducted in a carbon dioxide atmosphere. The parameters responsible for device applications such as, gas uptake capacity, response to test gas and recovery time of HAp film sensor are also investigated. SHI modified HAp films show the maximum enhancement in the gas response and also in increased gas uptake capacity for the fluence 3×10 11 ions/cm 2. Moreover, SHI has resulted in modification of gas response and recovery time for CO 2 gas. The remarkable observation is to note that SHI irradiation improves the sensor characteristics of the HAp films without affecting the working temperature (165 °C) of gas sensor.

  14. Surface modified hydroxyapatite thick films for CO{sub 2} gas sensing application: Effect of swift heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Mene, Ravindra U.; Mahabole, Megha P. [School of Physical Sciences, S.R.T.M. University, Nanded 431 606 (India); Khairnar, Rajendra S., E-mail: rskhairnarsps@gmail.co [School of Physical Sciences, S.R.T.M. University, Nanded 431 606 (India)

    2011-06-15

    Swift heavy ion irradiation (SHI) is used to modify the structural and gas sensing properties of Hydroxyapatite (HAp) thick films. The HAp thick films, prepared by screen printing technique, are irradiated with a variable fluence (3x10{sup 10} to 3x10{sup 13} ions/cm{sup 2}) of Ag{sup 7+} ions of 100 MeV energy. XRD shows gradual change in crystallinity of the matrix with increase in ion fluence. Atomic force microscopy reveals the agglomeration of grains with pronounced cluster type structure at relatively higher ion fluence. For confirmation of efficient gas sensing of pristine and irradiated HAp thick films, repeatability and reproducibility tests are conducted in a carbon dioxide atmosphere. The parameters responsible for device applications such as, gas uptake capacity, response to test gas and recovery time of HAp film sensor are also investigated. SHI modified HAp films show the maximum enhancement in the gas response and also in increased gas uptake capacity for the fluence 3x10{sup 11} ions/cm{sup 2}. Moreover, SHI has resulted in modification of gas response and recovery time for CO{sub 2} gas. The remarkable observation is to note that SHI irradiation improves the sensor characteristics of the HAp films without affecting the working temperature (165 {sup o}C) of gas sensor.

  15. The evolution of bat nucleic acid-sensing Toll-like receptors.

    Science.gov (United States)

    Escalera-Zamudio, Marina; Zepeda-Mendoza, M Lisandra; Loza-Rubio, Elizabeth; Rojas-Anaya, Edith; Méndez-Ojeda, Maria L; Arias, Carlos F; Greenwood, Alex D

    2015-12-01

    We characterized the nucleic acid-sensing Toll-like receptors (TLR) of a New World bat species, the common vampire bat (Desmodus rotundus), and through a comparative molecular evolutionary approach searched for general adaptation patterns among the nucleic acid-sensing TLRs of eight different bats species belonging to three families (Pteropodidae, Vespertilionidae and Phyllostomidae). We found that the bat TLRs are evolving slowly and mostly under purifying selection and that the divergence pattern of such receptors is overall congruent with the species tree, consistent with the evolution of many other mammalian nuclear genes. However, the chiropteran TLRs exhibited unique mutations fixed in ligand-binding sites, some of which involved nonconservative amino acid changes and/or targets of positive selection. Such changes could potentially modify protein function and ligand-binding properties, as some changes were predicted to alter nucleic acid binding motifs in TLR 9. Moreover, evidence for episodic diversifying selection acting specifically upon the bat lineage and sublineages was detected. Thus, the long-term adaptation of chiropterans to a wide variety of environments and ecological niches with different pathogen profiles is likely to have shaped the evolution of the bat TLRs in an order-specific manner. The observed evolutionary patterns provide evidence for potential functional differences between bat and other mammalian TLRs in terms of resistance to specific pathogens or recognition of nucleic acids in general. PMID:26503258

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

    International Nuclear Information System (INIS)

    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.)

  17. Removal of corper(II) Ions from aqueous solution by a lactic acid bacterium

    OpenAIRE

    M. Yilmaz(Department of Physics, Gazi University, Ankara); T. Tay; M. Kivanc; H. Turk

    2010-01-01

    Enterococcus faecium, a lactic acid bacterium (LAB), was evaluated for its ability to remove copper(II) ions from water. The effects of the pH, contact time, initial concentration of copper(II) ions, and temperature on the biosorption rate and capacity were studied. The initial concentrations of copper(II) ions used to determine the maximum amount of biosorbed copper(II) ions onto lyophilised lactic acid bacterium varied from 25 mg L-1 to 500 mg L-1. Maximum biosorption capacities were attain...

  18. 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

    2015-07-01

    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.

  19. Synthesis of a stable gold hydrosol by the reduction of chloroaurate ions by the amino acid, aspartic acid

    Indian Academy of Sciences (India)

    Saikat Mandal; P R Selvakannan; Sumant Phadtare; Renu Pasricha; Murali Sastry

    2002-10-01

    Development of reliable protocols for the synthesis of nanoparticles of well-defined sizes and good monodispersity is an important aspect of nanotechnology. In this paper, we present details of the synthesis of gold nanoparticles of good monodispersity by the reduction of aqueous chloroaurate ions by the amino acid, aspartic acid. The colloidal gold solution thus formed is extremely stable in time, indicating electrostatic stabilization via nanoparticle surface-bound amino acid molecules. This observation has been used to modulate the size of the gold nanoparticles in solution by varying the molar ratio of chloroaurate ions to aspartic acid in the reaction medium. Characterization of the aspartic acid-reduced gold nanoparticles was carried out by UV-visible spectroscopy, thermogravimetric analysis and transmission electron microscopy. The use of amino acids in the synthesis and stabilization of gold nanoparticle in water has important implications in the development of new protocols for generation of bioconjugate materials.

  20. Sensing of fatty acids for octanoylation of ghrelin involves a gustatory G-protein.

    Directory of Open Access Journals (Sweden)

    Sara Janssen

    Full Text Available BACKGROUND: Ghrelin is an important regulator of energy--and glucose homeostasis. The octanoylation at Ser(3 is essential for ghrelin's biological effects but the mechanisms involved in the octanoylation are unknown. We investigated whether the gustatory G-protein, α-gustducin, and the free fatty acid receptors GPR40 and GPR120 are involved in the fatty acid sensing mechanisms of the ghrelin cell. METHODS: Wild-type (WT and α-gustducin knockout (gust(-/- mice were fed a glyceryl trioctanoate-enriched diet (OD during 2 weeks. Ghrelin levels and gastric emptying were determined. Co-localization between GPR40, GPR120 and ghrelin or α-gustducin/α-transducin was investigated by immunofluorescence staining. The role of GPR120 in the effect of medium and long chain fatty acids on the release of ghrelin was studied in the ghrelinoma cell line, MGN3-1. The effect of the GPR40 agonist, MEDICA16, and the GPR120 agonist, grifolic acid, on ghrelin release was studied both in vitro and in vivo. RESULTS: Feeding an OD specifically increased octanoyl ghrelin levels in the stomach of WT mice but not of gust(-/- mice. Gastric emptying was accelerated in WT but not in gust(-/- mice. GPR40 was colocalized with desoctanoyl but not with octanoyl ghrelin, α-gustducin or α-transducin positive cells in the stomach. GPR120 only colocalized with ghrelin in the duodenum. Addition of octanoic acid or α-linolenic acid to MGN3-1 cells increased and decreased octanoyl ghrelin levels, respectively. Both effects could not be blocked by GPR120 siRNA. MEDICA16 and grifolic acid did not affect ghrelin secretion in vitro but oral administration of grifolic acid increased plasma ghrelin levels. CONCLUSION: This study provides the first evidence that α-gustducin is involved in the octanoylation of ghrelin and shows that the ghrelin cell can sense long- and medium-chain fatty acids directly. GPR120 but not GPR40 may play a role in the lipid sensing cascade of the ghrelin cell.

  1. Recent Advances in Understanding Amino Acid Sensing Mechanisms that Regulate mTORC1

    Directory of Open Access Journals (Sweden)

    Liufeng Zheng

    2016-09-01

    Full Text Available The mammalian target of rapamycin (mTOR is the central regulator of mammalian cell growth, and is essential for the formation of two structurally and functionally distinct complexes: mTORC1 and mTORC2. mTORC1 can sense multiple cues such as nutrients, energy status, growth factors and hormones to control cell growth and proliferation, angiogenesis, autophagy, and metabolism. As one of the key environmental stimuli, amino acids (AAs, especially leucine, glutamine and arginine, play a crucial role in mTORC1 activation, but where and how AAs are sensed and signal to mTORC1 are not fully understood. Classically, AAs activate mTORC1 by Rag GTPases which recruit mTORC1 to lysosomes, where AA signaling initiates. Plasma membrane transceptor L amino acid transporter 1 (LAT1-4F2hc has dual transporter-receptor function that can sense extracellular AA availability upstream of mTORC1. The lysosomal AA sensors (PAT1 and SLC38A9 and cytoplasmic AA sensors (LRS, Sestrin2 and CASTOR1 also participate in regulating mTORC1 activation. Importantly, AAs can be sensed by plasma membrane receptors, like G protein-coupled receptor (GPCR T1R1/T1R3, and regulate mTORC1 without being transported into the cells. Furthermore, AA-dependent mTORC1 activation also initiates within Golgi, which is regulated by Golgi-localized AA transporter PAT4. This review provides an overview of the research progress of the AA sensing mechanisms that regulate mTORC1 activity.

  2. Recent Advances in Understanding Amino Acid Sensing Mechanisms that Regulate mTORC1

    Science.gov (United States)

    Zheng, Liufeng; Zhang, Wei; Zhou, Yuanfei; Li, Fengna; Wei, Hongkui; Peng, Jian

    2016-01-01

    The mammalian target of rapamycin (mTOR) is the central regulator of mammalian cell growth, and is essential for the formation of two structurally and functionally distinct complexes: mTORC1 and mTORC2. mTORC1 can sense multiple cues such as nutrients, energy status, growth factors and hormones to control cell growth and proliferation, angiogenesis, autophagy, and metabolism. As one of the key environmental stimuli, amino acids (AAs), especially leucine, glutamine and arginine, play a crucial role in mTORC1 activation, but where and how AAs are sensed and signal to mTORC1 are not fully understood. Classically, AAs activate mTORC1 by Rag GTPases which recruit mTORC1 to lysosomes, where AA signaling initiates. Plasma membrane transceptor L amino acid transporter 1 (LAT1)-4F2hc has dual transporter-receptor function that can sense extracellular AA availability upstream of mTORC1. The lysosomal AA sensors (PAT1 and SLC38A9) and cytoplasmic AA sensors (LRS, Sestrin2 and CASTOR1) also participate in regulating mTORC1 activation. Importantly, AAs can be sensed by plasma membrane receptors, like G protein-coupled receptor (GPCR) T1R1/T1R3, and regulate mTORC1 without being transported into the cells. Furthermore, AA-dependent mTORC1 activation also initiates within Golgi, which is regulated by Golgi-localized AA transporter PAT4. This review provides an overview of the research progress of the AA sensing mechanisms that regulate mTORC1 activity. PMID:27690010

  3. 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.

  4. Distinct amino acid-sensing mTOR pathways regulate skeletal myogenesis.

    Science.gov (United States)

    Yoon, Mee-Sup; Chen, Jie

    2013-12-01

    Signaling through the mammalian target of rapamycin (mTOR) in response to amino acid availability controls many cellular and developmental processes. mTOR is a master regulator of myogenic differentiation, but the pathways mediating amino acid signals in this process are not known. Here we examine the Rag GTPases and the class III phosphoinositide 3-kinase (PI3K) Vps34, two mediators of amino acid signals upstream of mTOR complex 1 (mTORC1) in cell growth regulation, for their potential involvement in myogenesis. We find that, although both Rag and Vps34 mediate amino acid activation of mTORC1 in C2C12 myoblasts, they have opposing functions in myogenic differentiation. Knockdown of RagA/B enhances, whereas overexpression of active RagB/C mutants impairs, differentiation, and this inhibitory function of Rag is mediated by mTORC1 suppression of the IRS1-PI3K-Akt pathway. On the other hand, Vps34 is required for myogenic differentiation. Amino acids activate a Vps34-phospholipase D1 (PLD1) pathway that controls the production of insulin-like growth factor II, an autocrine inducer of differentiation, through the Igf2 muscle enhancer. The product of PLD, phosphatidic acid, activates the enhancer in a rapamycin-sensitive but mTOR kinase-independent manner. Our results uncover amino acid-sensing mechanisms controlling the homeostasis of myogenesis and underline the versatility and context dependence of mTOR signaling.

  5. Polyacrylamide hydrogel encapsulated E. coli expressing metal-sensing green fluorescent protein as a potential tool for copper ion determination

    OpenAIRE

    Tantimongcolwat, Tanawut; Isarankura-Na-Ayudhya, Chartchalerm; Srisarin, Apapan; Galla, Hans-Joachim; Prachayasittikul, Virapong

    2014-01-01

    A simple, inexpensive and field applicable metal determination system would be a powerful tool for the efficient control of metal ion contamination in various sources e.g. drinking-water, water reservoir and waste discharges. In this study, we developed a cell-based metal sensor for specific and real-time detection of copper ions. E. coli expressing metal-sensing green fluorescent protein (designated as TG1/(CG)6GFP and TG1/H6CdBP4GFP) were constructed and served as a metal analytical system....

  6. Adsorption of gaseous formaldehyde and carboxylic acids by ammonium-ion-exchanged alpha-zirconium phosphate.

    Science.gov (United States)

    Hayashi, A; Fujimoto, Y; Ogawa, Y; Nakayama, H; Tsuhako, M

    2005-03-01

    Ammonium-ion-exchanged alpha-Zr(HPO(4))(2)H(2)O (alpha-ZrP) was obtained as a single phase with the interlayer distance of 9.4 A by the ion-exchange of proton with ammonium ion. The ammonium ion-exchanged alpha-ZrP could adsorb ill-smelling gases, such as formaldehyde and carboxylic acids (formic acid, acetic acid, propionic acid, and butyric acid). The adsorption amounts of carboxylic acids increased in the order, butyric acidadsorption amount of formaldehyde was the same as that of butyric acid. It was cleared that the adsorbed formaldehyde was partially decomposed to formic acid and methanol by self oxidation-reduction reaction in the interlayer region as evidenced by solid-state NMR. Thereby the interlayer distance after the adsorption of formaldehyde expanded to 14.4 A. In the case of formic acid, it was cointercalated into the interlayer region, and the interlayer distance expanded to 11.1 A. On the other hand, the interlayer distance of the other carboxylic acid-adsorbed compounds decreased to 7.6 A due to release by the evacuation.

  7. Determination of nitrite ion and sulfanilic and orthanilic acids by differential pulse polarography

    Energy Technology Data Exchange (ETDEWEB)

    Sulaiman, S.T.

    1984-11-01

    The nitrite ion can be determined with a high degree of accuracy and sensitivity by differential pulse polarography utilizing the rapid and quantitative reaction between the nitrite ion and sulfanilic acid or orthanilic acid at pH 1.5. The experimental detection limit is shown to be 8.6 X 10/sup -8/ M (as NO/sub 2//sup -/) in simple aqueous solution. The method is further used to determine concentrations of sulfanilic acid down to 4 X 10/sup -7/ M and orthanilic acid down to 1.6 X 10/sup -6/ M under optimum conditions.

  8. Collision Cross Sections for 20 Protonated Amino Acids: Fourier Transform Ion Cyclotron Resonance and Ion Mobility Results

    Science.gov (United States)

    Anupriya; Jones, Chad A.; Dearden, David V.

    2016-08-01

    We report relative dephasing cross sections for the 20 biogenic protonated amino acids measured using the cross sectional areas by Fourier transform ion cyclotron resonance (CRAFTI) technique at 1.9 keV in the laboratory reference frame, as well as momentum transfer cross sections for the same ions computed from Boltzmann-weighted structures determined using molecular mechanics. Cross sections generally increase with increasing molecular weight. Cross sections for aliphatic and aromatic protonated amino acids are larger than the average trend, suggesting these side chains do not fold efficiently. Sulfur-containing protonated amino acids have smaller than average cross sections, reflecting the mass of the S atom. Protonated amino acids that can internally hydrogen-bond have smaller than average cross sections, reflecting more extensive folding. The CRAFTI measurements correlate well with results from drift ion mobility (IMS) and traveling wave ion mobility (TWIMS) spectrometric measurements; CRAFTI results correlate with IMS values approximately as well as IMS and TWIMS values from independent measurements correlate with each other. Both CRAFTI and IMS results correlate well with the computed momentum transfer cross sections, suggesting both techniques provide accurate molecular structural information. Absolute values obtained using the various methods differ significantly; in the case of CRAFTI, this may be due to errors in measurements of collision gas pressure, measurement of excitation voltage, and/or dependence of cross sections on kinetic energy.

  9. Collision Cross Sections for 20 Protonated Amino Acids: Fourier Transform Ion Cyclotron Resonance and Ion Mobility Results.

    Science.gov (United States)

    Anupriya; Jones, Chad A; Dearden, David V

    2016-08-01

    We report relative dephasing cross sections for the 20 biogenic protonated amino acids measured using the cross sectional areas by Fourier transform ion cyclotron resonance (CRAFTI) technique at 1.9 keV in the laboratory reference frame, as well as momentum transfer cross sections for the same ions computed from Boltzmann-weighted structures determined using molecular mechanics. Cross sections generally increase with increasing molecular weight. Cross sections for aliphatic and aromatic protonated amino acids are larger than the average trend, suggesting these side chains do not fold efficiently. Sulfur-containing protonated amino acids have smaller than average cross sections, reflecting the mass of the S atom. Protonated amino acids that can internally hydrogen-bond have smaller than average cross sections, reflecting more extensive folding. The CRAFTI measurements correlate well with results from drift ion mobility (IMS) and traveling wave ion mobility (TWIMS) spectrometric measurements; CRAFTI results correlate with IMS values approximately as well as IMS and TWIMS values from independent measurements correlate with each other. Both CRAFTI and IMS results correlate well with the computed momentum transfer cross sections, suggesting both techniques provide accurate molecular structural information. Absolute values obtained using the various methods differ significantly; in the case of CRAFTI, this may be due to errors in measurements of collision gas pressure, measurement of excitation voltage, and/or dependence of cross sections on kinetic energy. Graphical Abstract ᅟ. PMID:27220844

  10. Synthesis of hierarchical SnO2 nanoflowers with enhanced acetic acid gas sensing properties

    Science.gov (United States)

    Jin, W. X.; Ma, S. Y.; Tie, Z. Z.; Li, W. Q.; Luo, J.; Cheng, L.; Xu, X. L.; Wang, T. T.; Jiang, X. H.; Mao, Y. Z.

    2015-10-01

    Different morphologies hierarchical flower-like tin dioxide (SnO2) nanostructures were fabricated by changing the volume ratio of glycol and de-ionized water (Vg:Vw = 0, 1:2, 1:1 and 2:1) under a template-free and low-cost hydrothermal method and subsequent calcinations. The architectures, morphologies and gas sensing performances of the products were characterized by X-ray diffraction patterns (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and gas-sensing measurement device. It can be observed that all the nanoflowers were composed of two-dimensional (2D) nanosheets, and the thickness of nanosheets is only about 9 nm when Vg:Vw = 1:1. The sensor based on the product of Vg:Vw = 1:1 exhibited excellent gas sensing performance toward 500 ppm acetic acid at 260 °C, and the response value of this sensor was about 153.6, which was above 7.5 times higher than that of ammonia (about 20.3). In addition, the 3D flower-like SnO2 nanostructures exhibited not only high response and selectivity to ppm level acetone, but also fast response and recovery time within 10 s, demonstrating it can be used as a potential candidate for detecting acetic acid. Finally, the possible formation mechanism was proposed, too.

  11. The Role of the CAI-1 Fatty Acid Tail in the Vibrio cholerae Quorum Sensing Response

    Science.gov (United States)

    Perez, Lark J.; Ng, Wai-Leung; Marano, Paul; Brook, Karolina; Bassler, Bonnie L.; Semmelhack, Martin F.

    2013-01-01

    Quorum sensing is a mechanism of chemical communication among bacteria that enables collective behaviors. In V. cholerae, the etiological agent of the disease cholera, quorum sensing controls group behaviors including virulence factor production and biofilm formation. The major V. cholerae quorum-sensing system consists of the extracellular signal molecule called CAI-1 and its cognate membrane bound receptor called CqsS. Here, the ligand binding activity of CqsS is probed with structural analogs of the natural signal. Enabled by our discovery of a structurally simplified analog of CAI-1, we prepared and analyzed a focused library. The molecules were designed to probe the effects of conformational and structural changes along the length of the fatty acid tail of CAI-1. Our results, combined with pharmacophore modeling, suggest a molecular basis for signal molecule recognition and receptor fidelity with respect to the fatty acid tail portion of CAI-1. These efforts provide novel probes to enhance discovery of anti-virulence agents for the treatment of V. cholerae. PMID:23092313

  12. Effect of ions on the measurement of sulphuric acid in the CLOUD experiment at CERN

    OpenAIRE

    L. Rondo; A. Kürten; S. Ehrhart; Schobesberger, S.; A. Franchin; Junninen, H.; T. Petäjä; Sipilä, M.; Worsnop, D.R.; J. Curtius

    2014-01-01

    Ternary aerosol nucleation experiments were conducted in the CLOUD chamber at CERN in order to investigate the influence of ions on new particle formation. Neutral and ion-induced nucleation experiments, i.e., with and without the presence of ions, were carried out under precisely controlled conditions. The sulphuric acid concentration was measured with a Chemical Ionization Mass Spectrometer (CIMS) during the new particle formation experiments. The added ternar...

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

    International Nuclear Information System (INIS)

    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

  14. 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.

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

    International Nuclear Information System (INIS)

    The interaction between phytic acid and trivalent rare earth metal ions, viz., Ce3+, Pr3+, Nd3+, Sm3+, Gd3+, Tb3+, Dy3+ and HO3+ has been investigated potentiometrically at 25degC. The proton-ligand stability constants (pKYH) of phytic acid and the stability constants (logK) of metal complexes formed in aqueous medium (μ = 0.1 M NaClO4) 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

  16. Decontamination efficiency of citric acid and dissolution reaction of Fe3+ ion on TRIGA soil artificially contaminated with Co2+ ion

    International Nuclear Information System (INIS)

    A series of batch scale experiments was conducted to investigated the decontamination efficiency of citric acid on TRIGA soil artificially contaminated with Co2+ ion in the concentration range from 0.005M to 0.1M, under the pH solution of 3.0 to 10.0. The fraction diagram was calculated by equilibrium constant of Co2+ ion, Fe3+ ion and citric acid. The desorption rate of Co2+ ion was increased at low pH, but it was decreased at base zone. The dissolution rate of Fe3+ ion was same result against the various pH. The desorption reaction of Co2+ ion and the dissolution reaction of Fe3+ ion by citric acid both in acid solution and in base solution were suggested

  17. Trace determination of cobalt ion by using malic acid-malonic acid double substrate oscillating chemical system

    Institute of Scientific and Technical Information of China (English)

    Jie Wang; Wu Yang; Jie Ren; Miao Guo; Xiao Dong Chen; Wen Bin Wang; Jin Zhang Gao

    2008-01-01

    A novel kinetic method for determination of trace amounts of cobalt ion was proposed and validated. The method is based on adding malic acid into classical Belousov-Zhabotinskii (B-Z) oscillating chemical system to form a double substrate one. The results showed that when the concentration of cobalt ion was in the range of 5.27× 10-8 to 5.37×10-12mol L-1 the change of the oscillating period was directly proportional to the negative logarithm of cobalt ion concentration. The sensitivity and precision of the developed method were quite satisfactory. The limit of detection was down to 5.20 x 10-13 mol L-1 which was a highest sensitivity found for determination of metal ions using oscillating chemical reaction so far. Some factors influencing the determination were also examined. The method has been successfully used to determine cobalt ion in vitamin B12 injection.

  18. Warmth suppresses and desensitizes damage-sensing ion channel TRPA1

    Directory of Open Access Journals (Sweden)

    Wang Sen

    2012-03-01

    Full Text Available Abstract Background Acute or chronic tissue damage induces an inflammatory response accompanied by pain and alterations in local tissue temperature. Recent studies revealed that the transient receptor potential A1 (TRPA1 channel is activated by a wide variety of substances that are released following tissue damage to evoke nociception and neurogenic inflammation. Although the effects of a noxious range of cold temperatures on TRPA1 have been rigorously studied, it is not known how agonist-induced activation of TRPA1 is regulated by temperature over an innocuous range centred on the normal skin surface temperature. This study investigated the effect of temperature on agonist-induced currents in human embryonic kidney (HEK 293 cells transfected with rat or human TRPA1 and in rat sensory neurons. Results Agonist-induced TRPA1 currents in HEK293 cells were strongly suppressed by warm temperatures, and almost abolished at 39°C. Such inhibition occurred when TRPA1 was activated by either electrophilic or non-electrophilic agonists. Warming not only decreased the apparent affinity of TRPA1 for mustard oil (MO, but also greatly enhanced the desensitization and tachyphylaxis of TRPA1. Warming also attenuated MO-induced ionic currents in sensory neurons. These results suggest that the extent of agonist-induced activity of TRPA1 may depend on surrounding tissue temperature, and local hyperthermia during acute inflammation could be an endogenous negative regulatory mechanism to attenuate persistent pain at the site of injury. Conclusion These results indicate that warmth suppresses and desensitizes damage-sensing ion channel TRPA1. Such warmth-induced suppression of TRPA1 may also explain, at least in part, the mechanistic basis of heat therapy that has been widely used as a supplemental anti-nociceptive approach.

  19. Application of chromatographic techniques in the preparation of phosphoric acid from superphosphate fertilizer as phosphate ions source

    International Nuclear Information System (INIS)

    Ion exchange and high performance liquid chromatographic (HPLC) methods of analysis have been applied for the preparation of phosphoric acid from phosphate fertilizer as a source of phosphate ions. Amberlite IRA-400 (C1) has been used in ion-exchange separation. In HPLC an indirect spectrophotometric method of detection using phthalic acid in the mobile phase has been applied to detect the separated phosphoric acid. The phosphoric acid produced has been well characterized and compared with a standard. (author)

  20. A Zn(II) coordination polymer and its photocycloaddition product: syntheses, structures, selective luminescence sensing of iron(III) ions and selective absorption of dyes.

    Science.gov (United States)

    Hu, Fei-long; Shi, Yi-Xiang; Chen, Huan-Huan; Lang, Jian-Ping

    2015-11-21

    One coordination polymer [Zn2(L)2(bpe)2(H2O)2] (1) (L = 4,4'-((1,2-phenylenebis(methylene))bis(oxy))dibenzoic acid; bpe = (E)-1,2-di(pyridin-4-yl)ethene) was prepared and structurally determined. Compound 1 has a chain structure in which its pair of bpe ligands is arranged in a head-to-tail manner with their C=C bonds being close enough for a [2 + 2] cycloaddition reaction. Upon exposure to UV light, compound 1 undergoes a single-crystal-to-single-crystal (SCSC) [2 + 2] photodimerization to generate one 2D coordination polymer [Zn(L)(rctt-tpcb)0.5(H2O)] (1a) (rctt (regio cis, trans, trans)-tpcb = tetrakis(4-pyridyl)cyclobutane). The tpcb ligands in the crystals of 1a show an intriguing in situ thermal isomerisation. The nanospheres of 1 can be obtained by recrystallization in DMSO/alcohol. The nanospheres of 1a can also be readily produced from the corresponding nanospheres of 1 by the photocyclodimerization method. Compared with those of 1a, the nanospheres of 1 display highly selective sensing of Fe(3+) ions over mixed metal ions through fluorescence quenching. Moreover, the nanospheres of 1a can rapidly adsorb CR (congo red), MB (methylene blue) or RhB (rhodamine B) over MO (methyl orange) from aqueous solutions. This work offers a new photoinduced post-synthetic method for the synthesis of multifunctional MOFs, which show luminescence sensing of Fe(3+) ions and dye adsorption properties.

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

    OpenAIRE

    Ciprian Radovan; Codruţa Cofan

    2008-01-01

    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 param...

  2. Fundamental Study on the Segmented Flow Injection - Multiphase Flow Formation Towards Microchip-Based Multi-Ion Sensing

    Science.gov (United States)

    Hisamoto, Hideaki; Horiuchi, Takayuki; Hibara, Akihide; Tokeshi, Manabu; Kitamori, Takehiko

    A new fluid flow inside the microchannel was successfully developed. The flow created here involves segmented flow injection of plural organic phases into a microchannel followed by contact with a single aqueous phase to form stable organic-aqueous two-layer flow inside the microchannel. Fundamental study on the developed flow inside the microchannel was performed by monitoring the dye-doped segmented organic phases by thermal lens microscopy (TLM). Excellent repeatability and very small injection volume in developing segmented flow were realized. The new fluid flow created here is expected to allow us multi-ion sensing, which is not easily demonstrated by conventional ion sensor technology using a solvent polymeric membrane, by combining with neutral ionophore-based ion pair extraction using plural numbers of organic phases containing different ionophore molecules.

  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. Quantitative Assessment of Amino Acid Damage upon keV Ion Beam Irradiation Through FTIR Spectroscopy

    Science.gov (United States)

    Huang, Qing; Ke, Zhigang; Su, Xi; Yuan, Hang; Zhang, Shuqing; Yu, Zengliang

    2010-06-01

    Ion beam irradiation induces important biological effects and it is a long-standing task to acquire both qualitative and quantitative assessment of these effects. One effective way in the investigation is to utilize Fourier transformation infrared (FTIR) spectroscopy because it can offer sensitive and non-invasive measurements. In this paper a novel protocol was employed to prepare biomolecular samples in the form of thin and transversely uniform solid films that were suitable for both infrared and low-energy ion beam irradiation experiments. Under the irradiation of N+ and Ar+ ion beams of 25 keV with fluence ranging from 5×1015 ions/cm2 to 2.5×10 ions/cm2, the ion radio-sensitivity of four amino acids, namely, glycine, tyrosine, methionine and phenylalanine, were evaluated and compared. The ion beam irradiation caused biomolecular decomposition accompanied by molecular desorption of volatile species and the damage was dependent on ion type, fluence, energy and types of amino acids. The effectiveness of application of FTIR spectroscopy to the quantitative assessment of biomolecular damage dose effect induced by low-energy ion radiation was thus demonstrated.

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

    International Nuclear Information System (INIS)

    The photodegradation of bisphenol A (BPA), a suspected endocrine disruptor (ED), in simulated lake water containing algae, humic acid and Fe3+ ions was investigated. Algae, humic acid and Fe3+ ions enhanced the photodegradation of BPA. Photodegradation efficiency of BPA was 36% after 4 h irradiation in the presence of 6.5 x 109 cells L-1 raw Chlorella vulgaris, 4 mg L-1 humic acid and 20 μmol L-1 Fe3+. 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

  7. Distinct amino acid-sensing mTOR pathways regulate skeletal myogenesis.

    Science.gov (United States)

    Yoon, Mee-Sup; Chen, Jie

    2013-12-01

    Signaling through the mammalian target of rapamycin (mTOR) in response to amino acid availability controls many cellular and developmental processes. mTOR is a master regulator of myogenic differentiation, but the pathways mediating amino acid signals in this process are not known. Here we examine the Rag GTPases and the class III phosphoinositide 3-kinase (PI3K) Vps34, two mediators of amino acid signals upstream of mTOR complex 1 (mTORC1) in cell growth regulation, for their potential involvement in myogenesis. We find that, although both Rag and Vps34 mediate amino acid activation of mTORC1 in C2C12 myoblasts, they have opposing functions in myogenic differentiation. Knockdown of RagA/B enhances, whereas overexpression of active RagB/C mutants impairs, differentiation, and this inhibitory function of Rag is mediated by mTORC1 suppression of the IRS1-PI3K-Akt pathway. On the other hand, Vps34 is required for myogenic differentiation. Amino acids activate a Vps34-phospholipase D1 (PLD1) pathway that controls the production of insulin-like growth factor II, an autocrine inducer of differentiation, through the Igf2 muscle enhancer. The product of PLD, phosphatidic acid, activates the enhancer in a rapamycin-sensitive but mTOR kinase-independent manner. Our results uncover amino acid-sensing mechanisms controlling the homeostasis of myogenesis and underline the versatility and context dependence of mTOR signaling. PMID:24068326

  8. Ion flotation application for rare earths recovery from the products of apatite processing with sulfuric acid

    International Nuclear Information System (INIS)

    The possibility was proved experimentally of ion flotation applicability for REE recovery from phosphogypsum leaching solutions and extractional phosphoric acid. On treating leaching solutions with dialkylphosphoric acids a solid sublate was formed whose extraction degree was as high as 95 %. Treatment of extractional phosphoric acid with alkyl sulfates resulted in twice as high as high REE concentration in foam product that in the residue. 17 refs

  9. Facile Synthesis of Gold Nanoparticles by Amino Acid Asparagine: Selective Sensing of Arsenic.

    Science.gov (United States)

    Ghodake, Gajanan; Vassiliadis, Vassilios S; Choi, Jeong-Hak; Jang, Jiseon; Lee, Dae Sung

    2015-09-01

    The amino acid asparagine (ASP) was used as a benign reducing and stabilizing agent for the production of monodisperse gold nanoparticles (AuNPs) using green chemistry principles. With an increasing concentration of ASP (0.5 to 10 mM), the absorbance intensity at 525 nm increased; however, no effects on the color, size, or shape of the AuNPs were observed. Transmission electron microscope (TEM) images showed that the AuNPs were either hexagonal or spherical in shape and had an average size of approximately 10 ± 5 nm. Facile colorimetric assays of the AuNPs were applied to detect a variety of heavy metal ion species in water. In this study, the selective detection of arsenic ions (As (III) ions) by quenching, aggregation, and/or red-shifting of the surface plasmon resonance (SPR) was successfully achieved. The AuNPs sensor was sustainable as a visual colorimetric detection system and spectral assay of hazardous As (III) ions in the reaction medium; thus, it will be useful for aqueous assessment without using any sophisticated or expensive instruments. PMID:26716315

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

    Science.gov (United States)

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

    2016-09-01

    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-CO3-layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn2+ ions of Zn-Al-CO3-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-CO3-LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO3-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 -SO3 groups in ANTS-anchored on the surface of Zn-Al-CO3-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-CO3-LDH particles can afford a very sensitive system for the sensing FA in aqueous solution.

  11. Selenium speciation in urine by ion-pairing chromatography with perfluorinated carboxylic acids and ICP-MS detection

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Bendahl, L.; Sidenius, U.;

    2002-01-01

    in methanol. Two different perfluorinated carboxylic acids, heptafluorobutanoic acid (HFBA) and nonafluoropentanoic acid (NFPA), were used as ion-pairing agents in the separation. The selectivities of the ion-pairing agents were different. The separation was performed on a microbore column, which...

  12. Fe doped hydroxyapatite thick films modified via swift heavy ion irradiation for CO and CO{sub 2} gas sensing application

    Energy Technology Data Exchange (ETDEWEB)

    Mene, Ravindra U. [PDEA’s Annasaheb Waghire College of Science, Arts and Commerce, Otur 412409, M.S. (India); School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India); Mahabole, Megha P. [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India); Mohite, K.C. [Haribhai V. Desai College, Pune 411 002, M.S. (India); Khairnar, Rajendra S., E-mail: rskhairnarsps@gmail.com [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India)

    2014-01-25

    Graphical abstract: -- Highlights: • We report improved gas sensing properties of Fe-HAp films via heavy ion irradiation. • HAp films are tailored by addition of Fe ion as well as irradiation with variable ion fluence. • SHI irradiated substrate sense the CO and CO{sub 2} gases at relatively lower temperature. • Response and gas uptake capacity of sensors is improved for appropriate fluence 3 × 10{sup 11} ions/cm{sup 2}. • The enhanced sensor properties are attributed due to the surface modification by SHI. -- Abstract: Swift Heavy Ion irradiation (SHI) technique is utilized to modify the structure and surface morphology of Fe doped Hydroxyapatite (Fe-HAp) thick films for CO and CO{sub 2} gas sensing applications. Nano-crystalline HAp is synthesized by wet chemical precipitation route and ion exchange process is employed to replace of Ca ion with Fe ions. Thick film Fe-HAp sensors, having variable Fe doping concentrations, are prepared by using screen printing technique. The Fe-HAp thick films are irradiated using Ag{sup 7+} ion (100 MeV) with variable ion fluences ranging from 3 × 10{sup 10} to 3 × 10{sup 13} ions/cm{sup 2} for modifying the sensor surface. Structural and morphological changes with respect to ion fluence are observed by means of XRD, SEM and AFM analysis. The parameters such as operating temperature, response/recovery time, and uptake capacity for pristine and modified Fe-HAp sensors are experimentally determined. The investigations reveal that the SHI irradiated Fe-HAp film (3 × 10{sup 11} ions/cm{sup 2}) shows improved gas sensing characteristics at relatively lower operating temperature in comparison to pristine film. It is concluded that Fe-HAp film can be a potential candidate for developing low cost, energy saver and high performance CO and CO{sub 2} sensor.

  13. Separation of ions in acidic solution by capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, M.

    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.

  14. H +, Na +, and K + ion sensing properties of sodium and aluminum coimplanted LPCVD silicon oxynitride thin films

    Science.gov (United States)

    Shin, Paik-Kyun; Mikolajick, Thomas

    2003-02-01

    Three different silicon oxynitride layers were fabricated by varying NH 3/N 2O flow rate ratios in low pressure chemical vapor deposition (LPCVD) process. Sodium and aluminum were then coimplanted by implanting sodium ions with the energy of 100 keV and dose of 5×10 16 cm -2 into an aluminum buffer layer on silicon dioxide and three different silicon oxynitride layers. The composition of the as-deposited silicon oxynitride layers was analyzed by sputtered neutral mass spectroscopy (SNMS). Sodium, potassium and pH-sensing properties of the layers were investigated on an electrolyte-isolator-silicon (EIS) structure using high frequency capacitance-voltage (HF-CV) measurements. Differences of pH, sodium and potassium sensing properties between the as-deposited silicon oxynitride layers and the coimplanted silicon oxynitride layers were investigated. The sodium and aluminum coimplanted layers showed better sodium and potassium sensitivity as well as a lower sensitivity towards hydrogen ions. The effect is more pronounced for higher oxygen concentration in the layers. On the other hand the stability of ion response of the layers, in contrast, is better for the higher nitrogen content of the layers.

  15. Oxidation-reduction reactions of simple hydroxamic acids and plutonium(IV) ions in nitric acid

    OpenAIRE

    Carrott, M. J.; Fox, O. D.; LeGurun, G.; Jones, C J; Mason, C; Taylor, Robin; Andrieux, Fabrice; Boxall, Colin

    2008-01-01

    Simple hydroxamic acids such as formo- and aceto-hydroxamic acids have been proposed as suitable reagents for the separation of either Pu and/or Np from U in modified or single cycle Purex based solvent extraction processes designed to meet the emerging requirements of advanced fuel cycles. The stability of these hydroxamic acids is dominated by their decomposition through acid hydrolysis. Kinetic studies of the acid hydrolysis of formo- and acetohydroxamic acids are reported in the absence a...

  16. Polyacrylamide hydrogel encapsulated E. coli expressing metal-sensing green fluorescent protein as a potential tool for copper ion determination.

    Science.gov (United States)

    Tantimongcolwat, Tanawut; Isarankura-Na-Ayudhya, Chartchalerm; Srisarin, Apapan; Galla, Hans-Joachim; Prachayasittikul, Virapong

    2014-01-01

    A simple, inexpensive and field applicable metal determination system would be a powerful tool for the efficient control of metal ion contamination in various sources e.g. drinking-water, water reservoir and waste discharges. In this study, we developed a cell-based metal sensor for specific and real-time detection of copper ions. E. coli expressing metal-sensing green fluorescent protein (designated as TG1/(CG)6GFP and TG1/H6CdBP4GFP) were constructed and served as a metal analytical system. Copper ions were found to exert a fluorescence quenching effect, while zinc and cadmium ions caused minor fluorescence enhancement in the engineered bacterial suspension. To construct a user-friendly and reagentless metal detection system, TG1/H6CdBP4GFP and TG1/(CG)6GFP were encapsulated in polyacrylamide hydrogels that were subsequently immobilized on an optical fiber equipped with a fluorescence detection module. The sensor could be applied to measure metal ions by simply dipping the encapsulated bacteria into a metal solution and monitoring fluorescence changes in real time as a function of the metal concentration in solution. The sensor system demonstrated high specificity toward copper ions. The fluorescence intensities of the encapsulated TG1/(CG)6GFP and TG1/H6CdBP4GFP were quenched by approximately 70 % and 80 % by a high-dose of copper ions (50 mM), respectively. The level of fluorescence quenching exhibited a direct correlation with the copper concentration, with a linear correlation coefficient (r) of 0.99. The cell-based metal sensor was able to efficiently monitor copper concentrations ranging between 5 M and 50 mM, encompassing the maximum allowed copper contamination in drinking water (31.15 M) established by the WHO. Furthermore, the cell-based metal sensor could undergo prolonged storage for at least 2 weeks without significantly influencing the copper sensitivity. PMID:26417267

  17. Potentiometric determination of free acidity in presence of hydrolysable ions and a sequential determination of hydrazine.

    Science.gov (United States)

    Ganesh, S; Khan, Fahmida; Ahmed, M K; Pandey, S K

    2011-08-15

    A simple potentiometric method for the determination of free acidity in presence of hydrolysable ions and sequential determination of hydrazine is developed and described. Both free acid and hydrazine are estimated from the same aliquot. In this method, free acid is titrated with standard sodium carbonate solution after the metal ions in solutions are masked with EDTA. Once the end point for the free acid is determined at pH 3.0, an aliquot of formaldehyde is added to liberate the acid equivalent to hydrazine which is then titrated with the same standard sodium carbonate solution using an automatic titration system. The described method is simple, accurate and reproducible. This method is especially applicable to all ranges of nitric acid and heavy metal ion concentration relevant to Purex process used for nuclear fuel reprocessing. The overall recovery of nitric acid is 98.9% with 1.2% relative standard deviation. Hydrazine content has also been determined in the same aliquot with a recovery of nitric acid is 99% with 2% relative standard deviation. The major advantage of the method is that generation of corrosive analytical wastes containing oxalate or sulphate is avoided. Valuable metals like uranium and plutonium can easily be recovered from analytical waste before final disposal. PMID:21726724

  18. [Thermodynamic characteristics of nucleic acid complexes with silver ions].

    Science.gov (United States)

    Minasian, K A; Poletaev, A I; Borob'ev, A F

    1981-01-01

    By means of mixing reaction calorimetry the enthalpy of the complexes formation between Ag+ ions and DNA and dsRNA was measured. It was shown that Ag+ ions are able to form two types of complexes (I and II) with dsRNA. Using the method of the competitive reaction with chloride ions the stability constants of complex formation were obtained for dsRNA-Ag+ complexes for different temperatures. These measurements gave the delta H and delta S values for both complexes: delta HI = -74,9 +/- 7,1 kjouls/mol, delta SI = -100.0 +/- 25.0 jouls/mol deg; delta HII = -39,8 +/- 4,2 kjouls/mol, delta SII = +2 +/- 14 jouls/mol deg. The calorimetric results of delta H determination are the same within the limits of experimental errors. The enthalpy term of dsRNA-Ag+ complexes proved to bring the main contribution into the free energy of complex formation.

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

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This article deals with the determination of the adsorption properties of metal ions and humic acid in water 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 carried out by the batch method at room temperature. Adsorption of heavy metal ions (such as Cu2+, Cd2+) 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 Cu2+, Cd2+,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.

  20. Structure and simulation of a Zundel ion stabilized by 8-hydroxyquinoline-5, 7 disulphonic acid

    Science.gov (United States)

    Venkatakrishnan, Hasthi Annapurna; Venkatakrishnan, Ramaseshan; Pennathur, Anuj Krishnasundar; Pennathur, Gautam

    2016-07-01

    8-hydroxyquinoline-5, 7 disulphonic was synthesized and recrystallized in methanol to strip away molecules of water. The structure of the molecule revealed that Zundel ion was stabilized in the crystal. Ab-initio molecular dynamics simulation was then carried out to understand the dynamics of proton hopping in this complex. During the course of simulation, the Zundel ion coordinates with a water molecule to form an open H7O3+ structure. This transition state structure de-solvated rapidly forming Zundel ion facilitating proton hopping in the first solvation shell. One of the sulphonic acid groups in the 5 or 7 position of the 8-hydroxyquinoline 5,7 disulphonic acid bonds with the Zundel ion favoring the proton to be transferred to the nearby water molecule through the formation of proton defects. The simulation results support the structural diffusion mechanism and that charged complex migrates through the hydrogen bond network.

  1. Ion-exclusion chromatography determination of organic acid in uridine 5'-monophosphate fermentation broth.

    Science.gov (United States)

    Niu, Huanqing; Chen, Yong; Xie, Jingjing; Chen, Xiaochun; Bai, Jianxin; Wu, Jinglan; Liu, Dong; Ying, Hanjie

    2012-09-01

    Simultaneous determination of organic acids using ion-exclusion liquid chromatography and ultraviolet detection is described. The chromatographic conditions are optimized when an Aminex HPX-87H column (300 × 7.8 mm) is employed, with a solution of 3 mmol/L sulfuric acid as eluent, a flow rate of 0.4 mL/min and a column temperature of 60°C. Eight organic acids (including orotic acid, α-ketoglutaric acid, citric acid, pyruvic acid, malic acid, succinic acid, lactic acid and acetic acid) and one nucleotide are successfully quantified. The calibration curves for these analytes are linear, with correlation coefficients exceeding 0.999. The average recovery of organic acids is in the range of 97.6% ∼ 103.1%, and the relative standard deviation is in the range of 0.037% ∼ 0.38%. The method is subsequently applied to obtain organic acid profiles of uridine 5'-monophosphate culture broth fermented from orotic acid by Saccharomyces cerevisiae. These data demonstrate the quantitative accuracy for nucleotide fermentation mixtures, and suggest that the method may also be applicable to other biological samples. PMID:22634191

  2. Formic and acetic acid: Valence threshold photoelectron and photoionisation total ion yield studies

    International Nuclear Information System (INIS)

    Highlights: ► High-resolution threshold photoelectron spectrum of formic acid. ► High-resolution total photo-ion yield spectrum of formic acid. ► High-resolution threshold photoelectron spectrum of acetic acid. ► High-resolution total photo-ion yield spectrum of acetic acid. -- Abstract: The carboxylic acids (formic and acetic) have been studied using threshold photoelectron (TPE) and total photoion yield (TPIY) spectroscopies; simultaneously obtained spectra of formic acid (HCOOH) were recorded over the entire valence ionisation region from 11–21 eV at a resolution of ∼12 meV. Higher resolution spectra (∼6 meV) were also obtained in the energy region of the lowest two cationic states. Analysis of the TPE spectrum in this energy range agreed very favorably with the best available conventional photoelectron (PE) spectrum of formic acid. Autoionising Rydberg structure was observed in the TPIY spectrum of formic acid and is attributed primarily to the presence of the npa′ ← 8a′ Rydberg series converging on to the 32A′ ionic state of formic acid. Preliminary results, at a resolution of ∼8 meV, were obtained for acetic acid (CH3COOH) over the onset of the ionisation energy region. The TPE spectrum was found to be very similar to the best published photoelectron spectrum, but no Rydberg structure was observed in the TPIY spectrum.

  3. 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.

  4. 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.

  5. Hydrogen ion-selective electrolyte-gated organic field-effect transistor for pH sensing

    Science.gov (United States)

    Kofler, Johannes; Schmoltner, Kerstin; Klug, Andreas; List-Kratochvil, Emil J. W.

    2014-05-01

    A H+ ion-selective electrolyte-gated organic field-effect transistor (IS-EGOFET) with a broad detection range between pH 3 and pH 12, is presented. This pH sensor relies on an integrated EGOFET used as a transducer in combination with an ionophore-doped polymeric ion-selective membrane serving as a sensing element. The broad detection range was possible through a dynamic measurement protocol comprising a readjustment of the gate voltage, which ensures a stable device operation at a constant working point. The effectiveness of this dynamic approach is confirmed by stability investigations. On the basis of this pH sensor concept, the importance of an appropriate gating electrolyte is highlighted, giving insights into the working mechanism of EGOFETs.

  6. A sensitive and selective sensing platform based on CdTe QDs in the presence of l-cysteine for detection of silver, mercury and copper ions in water and various drinks.

    Science.gov (United States)

    Gong, Tingting; Liu, Junfeng; Liu, Xinxin; Liu, Jie; Xiang, Jinkun; Wu, Yiwei

    2016-12-15

    Water soluble CdTe quantum dots (QDs) have been prepared simply by one-pot method using potassium tellurite as stable tellurium source and thioglycolic acid (TGA) as stabilizer. The fluorescence of CdTe QDs can be improved 1.3-fold in the presence of l-cysteine (Cys), however, highly efficiently quenched in the presence of silver or mercury or copper ions. A sensitive and selective sensing platform for analysis of silver, mercury and copper ions has been simply established based on CdTe QDs in the presence of l-cysteine. Under the optimum conditions, excellent linear relationships exist between the quenching degree of the sensing platform and the concentrations of Ag(+), Hg(2+) and Cu(2+) ranging from 0.5 to 40ngmL(-1). By using masking agents of sodium diethyldithiocarbamate (DDTC) for Ag(+) and Cu(2+), NH4OH for Ag(+) and Hg(2+) and 1-(2-Pyridylazo)-2-naphthol (PAN) for Hg(2+) and Cu(2+), Hg(2+), Cu(2+) and Ag(+) can be exclusively detected in coexistence with other two ions, and the detection limits (3σ) were 0.65, 0.063 and 0.088ngmL(-1) for Ag(+), Hg(2+) and Cu(2+), respectively. This effective sensing platform has been used to detection of Ag(+), Hg(2+) and Cu(2+) in water and various drinks with satisfactory results. PMID:27451185

  7. Effect of ions on the measurement of sulphuric acid in the CLOUD experiment at CERN

    CERN Document Server

    Rondo, L; Ehrhart, S; Schobesberger, S; Franchin, A; Junninen, H; Petäjä, T; Sipilä, M; Worsnop, D R; Curtius, J

    2014-01-01

    Ternary aerosol nucleation experiments were conducted in the CLOUD chamber at CERN in order to investigate the influence of ions on new particle formation. Neutral and ion-induced nucleation experiments, i.e., with and without the presence of ions, were carried out under precisely controlled conditions. The sulphuric acid concentration was measured with a Chemical Ionization Mass Spectrometer (CIMS) during the new particle formation experiments. The added ternary trace gases were ammonia (NH3), dimethylamine (DMA, C2H7N) or oxidised products of pinanediol (PD, C10H18O2). When pinanediol was introduced into the chamber, an increase in the mass spectrometric signal used to determine the sulphuric acid concentration (m/z 97, i.e., HSO4−) was observed due to ions from the CLOUD chamber. The enhancement was only observed during ion-induced nucleation measurements by using either galactic cosmic rays (GCR) or the proton synchrotron (PS) pion beam for the ion generation, respectively. The ion effect typically invo...

  8. A library-screening approach for developing a fluorescence sensing array for the detection of metal ions.

    Science.gov (United States)

    Smith, David G; Sajid, Naveed; Rehn, Simone; Chandramohan, Ramya; Carney, Isaac J; Khan, Misbahul A; New, Elizabeth J

    2016-08-01

    Detection of individual metal ions is of importance across a range of fields of chemistry including environmental monitoring, and health and disease. Fluorescence is a highly sensitive technique and small fluorescent molecules are widely used for the detection and quantification of metal ions in various applications. Achieving specificity for a single metal from a single sensor is always a challenge. An alternative to selective sensing is the use of a number of non-specific sensors, in an array, which together respond in a unique pattern to each analyte. Here we show that screening a library of compounds can give a small sensor set that can be used to identify a range of metal ions following PCA and LDA. We explore a method for screening the initial compounds to identify the best performing sensors. We then present our method for reducing the size of the sensor array, resulting in a four-membered system, which is capable of identifying nine distinct metal ion species in lake water. PMID:27291513

  9. Effect of Li+ ion sensitization and optical temperature sensing in Gd2O3: Ho3+/Yb3+

    Science.gov (United States)

    Singh, Priyam; Shahi, P. K.; Rai, Anita; Bahadur, A.; Rai, S. B.

    2016-08-01

    Ho3+/Yb3+ codoped Gd2O3 phosphor has been synthesized by solution combustion method. The concentrations of Ho3+ and Yb3+ were optimized to be 0.3 and 2.0 mol% respectively for maximum emission intensity. The effect of Li+ ion co-doping on phase structure and photo luminescence were investigated. It is found that there is no change in phase of the sample due to Li+ ion co-doping. However the Upconversion (UC) and Downshifting (DS) emission show a remarkable enhancement in intensity. It is concluded that, this enhancement in the emission intensity is mainly due to the change in crystal field around the Ho3+ ion and reduction in quenching centers. The optimum doping concentration of Li+ ion was found to be 20 mol%. We have further explored the temperature sensing behavior using the FIR technique. The maximum sensitivity is found to be 0.0092 K-1 at 505 K.

  10. Analysis of a series of chlorogenic acid isomers using differential ion mobility and tandem mass spectrometry.

    Science.gov (United States)

    Willems, Jamie L; Khamis, Mona M; Mohammed Saeid, Waleed; Purves, Randy W; Katselis, George; Low, Nicholas H; El-Aneed, Anas

    2016-08-24

    Chlorogenic acids are among the most abundant phenolics found in the human diet. Of these, the mono-caffeoylquinic acids are the predominant phenolics found in fruits, such as apples and pears, and products derived from them. In this research, a comprehensive study of the electrospray ionization (ESI) tandem mass spectrometric (MS/MS) dissociation behavior of the three most common mono-caffeoylquinic acids, namely 5-O-caffeoylquinic acid (5-CQA), 3-O-caffeoylquinic acid (3-CQA) and 4-O-caffeoylquinic acid (4-CQA), were determined using both positive and negative ionization. All proposed structures of the observed product ions were confirmed with second-generation MS(3) experiments. Similarities and differences between the dissociation pathways in the positive and negative ion modes are discussed, confirming the proposed structures and the established MS/MS fingerprints. MS/MS dissociation was primarily driven via the cleavage of the ester bond linking the quinic acid moiety to the caffeic acid moiety within tested molecules. Despite being structural isomers with the same m/z values and dissociation behaviors, the MS/MS data in the negative ion mode was able to differentiate the three isomers based on ion intensity for the major product ions, observed at m/z 191, 179 and 173. This differentiation was consistent among various MS instruments. In addition, ESI coupled with high-field asymmetric waveform ion mobility spectrometry-mass spectrometry (ESI-FAIMS-MS) was employed for the separation of these compounds for the first time. By combining MS/MS data and differential ion mobility, a method for the separation and identification of mono-caffeoylquinic in apple/pear juice samples was developed with a run time of less than 1 min. It is envisaged that this methodology could be used to identify pure juices based on their chlorogenic acid profile (i.e., metabolomics), and could also be used to detect juice-to-juice adulteration (e.g., apple juice addition to pear juice

  11. Analysis of a series of chlorogenic acid isomers using differential ion mobility and tandem mass spectrometry.

    Science.gov (United States)

    Willems, Jamie L; Khamis, Mona M; Mohammed Saeid, Waleed; Purves, Randy W; Katselis, George; Low, Nicholas H; El-Aneed, Anas

    2016-08-24

    Chlorogenic acids are among the most abundant phenolics found in the human diet. Of these, the mono-caffeoylquinic acids are the predominant phenolics found in fruits, such as apples and pears, and products derived from them. In this research, a comprehensive study of the electrospray ionization (ESI) tandem mass spectrometric (MS/MS) dissociation behavior of the three most common mono-caffeoylquinic acids, namely 5-O-caffeoylquinic acid (5-CQA), 3-O-caffeoylquinic acid (3-CQA) and 4-O-caffeoylquinic acid (4-CQA), were determined using both positive and negative ionization. All proposed structures of the observed product ions were confirmed with second-generation MS(3) experiments. Similarities and differences between the dissociation pathways in the positive and negative ion modes are discussed, confirming the proposed structures and the established MS/MS fingerprints. MS/MS dissociation was primarily driven via the cleavage of the ester bond linking the quinic acid moiety to the caffeic acid moiety within tested molecules. Despite being structural isomers with the same m/z values and dissociation behaviors, the MS/MS data in the negative ion mode was able to differentiate the three isomers based on ion intensity for the major product ions, observed at m/z 191, 179 and 173. This differentiation was consistent among various MS instruments. In addition, ESI coupled with high-field asymmetric waveform ion mobility spectrometry-mass spectrometry (ESI-FAIMS-MS) was employed for the separation of these compounds for the first time. By combining MS/MS data and differential ion mobility, a method for the separation and identification of mono-caffeoylquinic in apple/pear juice samples was developed with a run time of less than 1 min. It is envisaged that this methodology could be used to identify pure juices based on their chlorogenic acid profile (i.e., metabolomics), and could also be used to detect juice-to-juice adulteration (e.g., apple juice addition to pear juice).

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    OpenAIRE

    Wei Hui; Donohoe Bryon S; Vinzant Todd B; Ciesielski Peter N; Wang Wei; Gedvilas Lynn M; Zeng Yining; Johnson David K; Ding Shi-You; Himmel Michael E; Tucker Melvin P

    2011-01-01

    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 mechan...

  15. Structural basis for regulation of human calcium-sensing receptor by magnesium ions and an unexpected tryptophan derivative co-agonist.

    Science.gov (United States)

    Zhang, Chen; Zhang, Tuo; Zou, Juan; Miller, Cassandra Lynn; Gorkhali, Rakshya; Yang, Jeong-Yeh; Schilmiller, Anthony; Wang, Shuo; Huang, Kenneth; Brown, Edward M; Moremen, Kelley W; Hu, Jian; Yang, Jenny J

    2016-05-01

    Ca(2+)-sensing receptors (CaSRs) modulate calcium and magnesium homeostasis and many (patho)physiological processes by responding to extracellular stimuli, including divalent cations and amino acids. We report the first crystal structure of the extracellular domain (ECD) of human CaSR bound with Mg(2+) and a tryptophan derivative ligand at 2.1 Å. The structure reveals key determinants for cooperative activation by metal ions and aromatic amino acids. The unexpected tryptophan derivative was bound in the hinge region between two globular ECD subdomains, and represents a novel high-affinity co-agonist of CaSR. The dissection of structure-function relations by mutagenesis, biochemical, and functional studies provides insights into the molecular basis of human diseases arising from CaSR mutations. The data also provide a novel paradigm for understanding the mechanism of CaSR-mediated signaling that is likely shared by the other family C GPCR [G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor] members and can facilitate the development of novel CaSR-based therapeutics. PMID:27386547

  16. Analyses on Radiation Effects in Solid Amino Acids Induced by Low Energy Fe~+ Ion Beams

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Radiation effects in Solid samples of L(+)-cysteine and L(+)-cysteine hydroehloride monohydrate induced by 110 keV Fe~+ion implantation were characterized with FTIR, ESR,HPLC and ESI-FTMS.It was validated that solid samples of the irradiated amino acids were damaged to a certain extent,and some new groups or molecular products formed.

  17. IRMPD spectroscopy b(2) ions from protonated tripeptides with 4-aminomethyl benzoic acid residues

    NARCIS (Netherlands)

    M. J. Kullman; S. Molesworth; G. Berden; J. Oomens; M. van Stipdonk

    2012-01-01

    Collision-induced dissociation (CID) of the peptide alanine-4-aminomethylbenzoic acid-glycine, A(AMBz)G generates a prominent b2 ion despite a previous report [E.R. Talaty, T.J. Cooper, S.M. Osburn, M.J. Van Stipdonk, Collision-induced dissociation of protonated tetrapeptides containing β-alanine, γ

  18. IRMPD spectroscopy b(2) ions from protonated tripeptides with 4-aminomethyl benzoic acid residues

    NARCIS (Netherlands)

    Kullman, M. J.; Molesworth, S.; G. Berden,; Oomens, J.; Van Stipdonk, M.

    2012-01-01

    Collision-induced dissociation (CID) of the peptide alanine-4-aminomethylbenzoic acid-glycine, A(AMBz)G generates a prominent b(2) ion despite a previous report [ER. Talaty, T.J. Cooper, S.M. Osburn, M.J. Van Stipdonk, Collision-induced dissociation of protonated tetrapeptides containing beta-alanin

  19. Ion-Induced Fragmentation of Amino Acids : Effect of the Environment

    NARCIS (Netherlands)

    Maclot, Sylvain; Capron, Michael; Maisonny, Remi; Lawicki, Arkadiusz; Mery, Alain; Rangama, Jimmy; Chesnel, Jean-Yves; Bari, Sadia; Hoekstra, Ronnie; Schlatholter, Thomas; Manil, Bruno; Adoui, Lamri; Rousseau, Patrick; Huber, Bernd A.

    2011-01-01

    In general, radiation-induced fragmentation of small amino acids is governed by the cleavage of the C-C(alpha) bond. We present results obtained with 300 keV Xe(20+) ions that allow molecules (glycine and valine) to be ionised at large distances without appreciable energy transfer. Also in the prese

  20. PERVAPORATION SEPARATION OF WATER-ACETIC ACID MIXTURES THROUGH AN-co-AA MEMBRANES TREATED WITH RARE EARTH METAL IONS

    Institute of Scientific and Technical Information of China (English)

    SHEN Zhiquan; ZHANG Fuyao; ZHANG Yifeng

    1995-01-01

    Pervaporation separation of water-acetic acid mixtures through Poly (AN-co-AA)membranes and rare earth metal ions treated Poly(AN-co-AA)membranes was investigated for the first time. The results showed that the treatment with rare earth metal ions could greatly improve the characteristics of the separation of water-acetic acid mixtures.

  1. Scandium and zirconium ion complexing with salicylic acid

    International Nuclear Information System (INIS)

    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 (pH2 (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 β1=(3+-1)x102; β2=(5.0+-0.6)x104; β3=(5.3+-0.3)x106

  2. The reduction process of phytic acid silver ion system: A pulse radiolysis study

    Science.gov (United States)

    Joshi, Ravi; Mukherjee, Tulsi

    2007-05-01

    Reduction of silver ion in a silver-phytic acid (1:1 ratio) system has been studied using pulse radiolysis technique. Time-resolved transformation of the intermediates, Ag +→Ag 0→Ag 2+→Ag 32+, has been clearly observed in the reduction of silver-phytic acid (1:1) system. The effect of phytic acid on the formation and decay of initial silver clusters has been also studied. The surface plasmon absorption band of stable silver nanoparticle (410 nm) and dynamic light scattering technique has been used to characterize the nanoparticles and measure the average size ( Rav=100 nm).

  3. The reduction process of phytic acid-silver ion system: A pulse radiolysis study

    International Nuclear Information System (INIS)

    Reduction of silver ion in a silver-phytic acid (1:1 ratio) system has been studied using pulse radiolysis technique. Time-resolved transformation of the intermediates, Ag+→Ag0→Ag2+→Ag32+, has been clearly observed in the reduction of silver-phytic acid (1:1) system. The effect of phytic acid on the formation and decay of initial silver clusters has been also studied. The surface plasmon absorption band of stable silver nanoparticle (410 nm) and dynamic light scattering technique has been used to characterize the nanoparticles and measure the average size (R av=100 nm)

  4. Using poly(3-aminophenylboronic acid) thin film with binding-induced ion flux blocking for amperometric detection of hemoglobin A1c.

    Science.gov (United States)

    Wang, Jen-Yuan; Chou, Tse-Chuan; Chen, Lin-Chi; Ho, Kuo-Chuan

    2015-01-15

    This study reports a novel enzyme-free, label-free amperometric method for direct detection of hemoglobin A1c (Hb(A1c)), a potent biomarker for diabetes diagnosis and prognosis. The method relies on an electrode modified with poly(3-aminophenylboronic acid) (PAPBA) nanoparticles (20-50 nm) and a sensing scheme named "binding-induced ion flux blocking." The PAPBA nanoparticles were characterized by FT-IR, XPS, TEM, and SEM. Being a polyaniline derivative, PAPBA showed an ion-dependent redox behavior, in which insertion or extraction of ions into or out of PABPA occurred for charge balance during the electron transfer process. The polymer allowed Hb(A1c) selectively bound to its surface via forming the cis-diol linkage between the boronic acid and sugar moieties. Voltammetric analyses showed that Hb(A1c) binding decreased the redox current of PAPBA; however, the binding did not alter the redox potentials and the apparent diffusivities of ions. This suggests that the redox current of PAPBA decreased due to an Hb(A1c) binding-induced ion flux blocking mechanism, which was then verified and characterized through an in situ electrochemical quartz crystal microbalance (EQCM) study. Assay with Hb(A1c) by differential pulse voltammetry (DPV) indicates that the peak current of a PAPBA electrode has a linear dependence on the logarithm of Hb(A1c) concentration ranging from 0.975 to 156 μM. The Hb(A1c) assay also showed high selectivity against ascorbic acid, dopamine, uric acid, glucose and bovine serum albumin. This study has demonstrated a new method for developing an electrochemical Hb(A1c) biosensor and can be extended to other label-free, indicator-free protein biosensors based on a similar redox polymer electrode. PMID:25113050

  5. Ionophore-Based Voltammetric Ion Activity Sensing with Thin Layer Membranes.

    Science.gov (United States)

    Cuartero, Maria; Crespo, Gaston A; Bakker, Eric

    2016-02-01

    As shown in recent work, thin layer ion-selective multi-ionophore membranes can be interrogated by cyclic voltammetry to detect the ion activity of multiple species simultaneously and selectively. Additional fundamental evidence is put forward on ion discrimination with thin multi-ionophore-based membranes with thicknesses of 200 ± 25 nm and backside contacted with poly-3-octylthiophene (POT). An anodic potential scan partially oxidizes the POT film (to POT(+)), thereby initiating the release of hydrophilic cations from the membrane phase to the sample solution at a characteristic potential. Varying concentration of added cation-exchanger demonstrates that it limits the ion transfer charge and not the deposited POT film. Voltammograms with multiple peaks are observed with each associated with the transfer of one type of ion (lithium, potassium, and sodium). Experimental conditions (thickness and composition of the membrane and concentration of the sample) are chosen that allow one to describe the system by a thermodynamic rather than kinetic model. As a consequence, apparent stability constants for sodium, potassium, and lithium (assuming 1:1 stoichiometry) with their respective ionophores are calculated and agree well with the values obtained by the potentiometric sandwich membrane technique. As an analytical application, a membrane containing three ionophores was used to determine lithium, sodium, and potassium in artificial samples at the same location and within a single voltammetric scan. Lithium and potassium were also determined in undiluted human plasma in the therapeutic concentration range. PMID:26712342

  6. New, enhanced phage-based bacterium detection/identification by COnductance-Noise-Sensing-of-Phage-Triggered-Ion-Cascades (CON-SEPTIC)

    CERN Document Server

    Kish, Laszlo B

    2010-01-01

    We point out the reasons for the problems with the reproducibility and sensitivity of the earlier page-based bacterium detection/identification method SEPTIC (Sensing-of-Phage-Triggered-Ion-Cascades). The main weaknesses originate from the DC field/current nature of the method. Then we propose a new principle and method, CON-SEPTIC (COnductance-Noise-Sensing-of-Phage-Triggered-Ion-Cascades), which, similarly to SEPTIC, also utilizes the ion release during phage infection. However CON-SEPTIC, instead of sensing the electrical field (voltage) during phage infection, uses the measurement of the AC conductivity and its fluctuations (conductance noise) to detect slow fluctuations of the ionic concentration due to infected bacteria. In this way, the effects of electrode material, corrosion, drift, ageing, surface imperfections, 1/f potential fluctuations and even thermal noise (with two-frequency or phase drive) are absent and the detection of a single bacterium maybe possible. Moreover, because no electrical poten...

  7. Ionization Efficiency of Doubly Charged Ions Formed from Polyprotic Acids in Electrospray Negative Mode

    Science.gov (United States)

    Liigand, Piia; Kaupmees, Karl; Kruve, Anneli

    2016-07-01

    The ability of polyprotic acids to give doubly charged ions in negative mode electrospray was studied and related to physicochemical properties of the acids via linear discriminant analysis (LDA). It was discovered that the compound has to be strongly acidic (low p K a1 and p K a2) and to have high hydrophobicity (log P ow) to become multiply charged. Ability to give multiply charged ions in ESI/MS cannot be directly predicted from the solution phase acidities. Therefore, for the first time, a quantitative model to predict the charge state of the analyte in ESI/MS is proposed and validated for small anions. Also, a model to predict ionization efficiencies of these analytes was developed. Results indicate that acidity of the analyte, its octanol-water partition coefficient, and charge delocalization are important factors that influence ionization efficiencies as well as charge states of the analytes. The pH of the solvent was also found to be an important factor influencing the ionization efficiency of doubly charged ions.

  8. Luminescent properties of [UO2(TFA)2(DMSO)3], a promising material for sensing and monitoring the uranyl ion

    International Nuclear Information System (INIS)

    An uranyl complex [UO2(TFA)2(DMSO)3] (TFA=deprotonated trifluoroacetic acid; DMSO=dimethyl sulfoxide) has been successfully synthesized by reacting UO2(CH3COO)2 ·H2 O with one equivalent of (CF3 CO)2 O and DMSO. The complex has been characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis, FTIR spectroscopy, thermal analysis and absorption and emission spectroscopies. The spectroscopic properties of the material make it suitable for its application in the sensing and monitoring of uranyl in the PUREX process. (author)

  9. Fast removal of heavy metal ions and phytic acids from water using new modified chelating fiber

    Institute of Scientific and Technical Information of China (English)

    Li Xu; Jin Nan Wang; Ying Meng; Ai Min Li

    2012-01-01

    The graft copolymerization of acrylic acid (AA) onto polyethylene glycol terephthalate (PET) fiber initiated by benzoy peroxide (BPO) was carried out in heterogeneous media.Moreover,modification of the grafted PET fiber (PET-AA) was done by changing the carboxyl group into acylamino group through the reaction with dimethylamine.The modified chelating fiber (NDWJN 1) was characterized using elementary analysis,SEM and FT-IR spectroscopy.Adsorption kinetic curves indicated that NDWJN1 could fast remove heavy metal ions and phytic acids from water effectively.Furthermore,batch kinetic studies indicated that heavy metal ions adsorbed to NDWJN1 could be fitted well by both pseudo-first-order and pseudo-second-order adsorption equations,but the intra-particle diffusion plaved a dominant role in the adsorption of phvtic acids.

  10. Negative Ion Photoelectron Spectroscopy Reveals Thermodynamic Advantage of Organic Acids in Facilitating Formation of Bisulfate Ion Clusters: Atmospheric Implications

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Gao-Lei; Lin, Wei; Deng, Shihu; Zhang, Jian; Zheng, Weijun; Paesani, Francesco; Wang, Xue B.

    2013-03-07

    Recent lab and field measurements have indicated critical roles of organic acids in enhancing new atmospheric aerosol formation. Such findings have stimulated theoretical studies with the aim of understanding interaction of organic acids with common aerosol nucleation precursors like bisulfate (HSO4-). In this Letter, we report a combined negative ion photoelectron spectroscopic and theoretical investigation of molecular clusters formed by HSO4- with succinic acid (SUA, HO2C(CH2)2CO2H), HSO4-(SUA)n (n = 0-2), along with HSO4-(H2O)n and HSO4-(H2SO4)n. It is found that one SUA molecule can stabilize HSO4- by ca. 39 kcal/mol, triple the corresponding value that one water molecule is capable of (ca. 13 kcal/mol). Molecular dynamics simulations and quantum chemical calculations reveal the most plausible structures of these clusters and attribute the stability of these clusters due to formation of strong hydrogen bonds. This work provides direct experimental evidence showing significant thermodynamic advantage by involving organic acid molecules to promote formation and growth in bisulfate clusters and aerosols.

  11. Ratiometric Organic Fibers for Localized and Reversible Ion Sensing with Micrometer‐Scale Spatial Resolution

    Science.gov (United States)

    Moffa, Maria; Rinaldi, Rosaria

    2015-01-01

    A fundamental issue in biomedical and environmental sciences is the development of sensitive and robust sensors able to probe the analyte of interest, under physiological and pathological conditions or in environmental samples, and with very high spatial resolution. In this work, novel hybrid organic fibers that can effectively report the analyte concentration within the local microenvironment are reported. The nanostructured and flexible wires are prepared by embedding fluorescent pH sensors based on seminaphtho‐rhodafluor‐1‐dextran conjugate. By adjusting capsule/polymer ratio and spinning conditions, the diameter of the fibers and the alignment of the reporting capsules are both tuned. The hybrid wires display excellent stability, high sensitivity, as well as reversible response, and their operation relies on effective diffusional kinetic coupling of the sensing regions and the embedding polymer matrix. These devices are believed to be a powerful new sensing platform for clinical diagnostics, bioassays and environmental monitoring. PMID:26539625

  12. Proton and metal ion binding to natural organic polyelectrolytes-II. Preliminary investigation with a peat and a humic acid

    Science.gov (United States)

    Marinsky, J.A.; Reddy, M.M.

    1984-01-01

    We summarize here experimental studies of proton and metal ion binding to a peat and a humic acid. Data analysis is based on a unified physico-chemical model for reaction of simple ions with polyelectrolytes employing a modified Henderson-Hasselbalch equation. Peat exhibited an apparent intrinsic acid dissociation constant of 10-4.05, and an apparent intrinsic metal ion binding constant of: 400 for cadmium ion; 600 for zinc ion; 4000 for copper ion; 20000 for lead ion. A humic acid was found to have an apparent intrinsic proton binding constant of 10-2.6. Copper ion binding to this humic acid sample occurred at two types of sites. The first site exhibited reaction characteristics which were independent of solution pH and required the interaction of two ligands on the humic acid matrix to simultaneously complex with each copper ion. The second complex species is assumed to be a simple monodentate copper ion-carboxylate species with a stability constant of 18. ?? 1984.

  13. Carbon dots with tunable emission, controllable size and their application for sensing hypochlorous acid

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhaoxia; Lin, Feng; Hu, Ming; Li, Chunxiang; Xu, Ting; Chen, Chuan; Guo, Xiangqun, E-mail: xqguo@xmu.edu.cn

    2014-07-01

    Optically tunable carbon dots (CDs) were fabricated through a simple one-step microwave-assisted procedure. These carbonaceous nanoparticles exhibited tunable emission under a single wavelength excitation, controllable size without any tedious separation process and stabilities towards photobleaching and high ionic strength. The effects of size difference and surface property on the fluorescence behaviors of CDs were explored through a post-reduction/oxidation method. Experimental results also demonstrated the fluorescence of CDs could be tuned when exposed to H{sub 2}O{sub 2}/AcOH solutions. Moreover, the use of as-synthesized CDs as a chemical sensor for the quantification of hypochlorous acid (HClO) has been preliminarily tested, showing high sensitivity and selectivity towards HClO over other common ions. The superior optical properties would enable the use of CDs in multiplexed optical coding of biomolecules, light-emitting devices and biological applications. - Highlights: • Carbon dots exhibited multiple colors under a single wavelength excitation. • Microwave or post-oxidation methods were employed to tune the emission wavelengths. • The as-prepared particles had controllable size without tedious separation process. • High sensitivity and selectivity towards hypochlorous acid were demonstrated.

  14. The study on the methods of testing the sulphuric acid and the phosphoric acid in the air in workshops at the same time by chromatography of ions

    Institute of Scientific and Technical Information of China (English)

    Deng-Yan Long; Yan-Ling Huang; Ying-Ying Zhao

    2015-01-01

    Objective:To discuss the method and result of testing the sulphuric acid and the phosphoric acid in the air in workshops at the same time by chromatography of ions.Method:to measure the sulphuric acid and the phosphoric acid in the air in workshops by adopting chromatography of ions. During the experiment, collect the sulphuric acid and the phosphoric acid in the air by using porous glass plates and put them into ultrapure water, or by using microporous filtering film, adopting ultrasonic elution with ultrapure water, testing them with ion chromatograph after filtering through a 0.2 μm microporous filtering film. The operating conditions of chromatography of ions includes Type Ionpac AS19 separator column (4×250 mm), ASRS300 (4 mm) anion suppressor, Type Ionpac AG19 guard column, KOH eluent and conductivity detector.Result: The testing the sulphuric acid and the phosphoric acid at the same time through chromatography of ions turns out high resolution, good linearity with the correlation over 0.999. The accuracy can be controlled between 1.6%-5.5% under the testing; the percentage of accuracy can be guaranteed between 92%-107% with high sampling and analysis efficiency.Conclusion: The method can turn out ideal results by testing the sulphuric acid and the phosphoric acid at the same time. It is simple operations, Sensitive and accurate. It is worth being used widely.

  15. Visual sensing of fluoride ions by dipyrrolyl derivatives bearing electron-withdrawing groups

    Indian Academy of Sciences (India)

    Tamal Ghosh; Bhaskar G Maiya

    2004-01-01

    Two new, easy-to-prepare dipyrrolyl derivatives endowed with electron-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.

  16. Influence of metal ions binding on free radical concentration in humic acids. A quantitative electron paramagnetic resonance study

    Energy Technology Data Exchange (ETDEWEB)

    Jerzykiewicz, M.; Jezierski, A. [Wroclaw Univ. (Poland). Faculty of Chemistry; Czechowski, F. [Wroclaw Univ. of Technology (Poland). Inst. of Organic Chemistry, Biochemistry and Biotechnology; Drozd, J. [Agricultural Univ. of Wroclaw (Poland). Inst. of Soil Science and Agricultural Environment Protection

    2002-07-01

    The influence of metal ions, e.g. Co(II), Cu(II), Mn(II), Ni(II), Fe(II), on free radical concentration in humic acids isolated from soil, peat and compost was investigated by electron paramagnetic resonance (EPR). The results show that metal ions with unfilled d-shell exhibit antiferromagnetic interactions with semiquinone radicals. Moreover, coordinated metals shift the quinone-semiquinone-hydroquinone equilibrium in the macromolecular matrix of humic acids. A strong decrease of semiquinone radical concentration in humic acid-metal complexes is observed. This effect is caused by interactions of metal ions with oxygen-containing stable radicals occurring in the aromatic systems of humic acids. Furthermore, the effect of metal coordination on free radical concentration in humic acids-metal complexes depends on the humic acid origin. FTIR spectroscopy was also used as an additional tool for studies of the metal ions interactions with carboxylic groups. [author].

  17. Organic acids and inorganic anions in Bayer liquors by ion chromatography after solid-phase extraction

    Institute of Scientific and Technical Information of China (English)

    ZHONG Fu-jin; CHEN Xiao-qing; ZHANG Shu-chao; LI Yue-ping

    2007-01-01

    A method for the simultaneous separation and determination of organic acids and inorganic anions in Bayer liquors was developed by gradient ion chromatography with suppressed conductivity detection. Formate, acetate, propionate, oxalate, succinate,glutarate, fluoride, chloride and sulfate were separated and determined in 33 min. The samples were pretreated with solid-phase extraction, which has high selectivity for removing a large number of metallic ions in the Bayer liquors, and filtered with a 0.45 μm filter membrane before being injected into the ion chromatographic system. The separation of six organic acids and three inorganic anions was achieved on an IonPac AS11-HC column with KOH as the eluent, and the detection was performed by a conductivity detection mode. No interference is found in the presence of fluorate, chlorate and sulphate when organic acids are determined. The calibration graphs of peak area for all the analytes are linear over a wide range. The relative standard derivation of the peak area of analytes is less than 2.14%. Under optimum conditions the detection ranges from 0.2 to 100.0 mg/L. The average recoveries of the added standards are between 94.3% and 102.8%.

  18. Determination of haloacetic acids concentrations in hospital effluent after chlorination by ion chromatography

    Institute of Scientific and Technical Information of China (English)

    SUN Ying-xue; GU Ping

    2007-01-01

    The ion chromatography combined solid phase extraction (SPE) method was developed for the analysis of low concentration haloacetic acids(HAAs),a calss of disinfection by-products formed as a result of chlorination of hospital wastewater. The monitored HAAs included monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, dibromoacetic acid and trichloroacetic acid. The method employed a sodium hydroxide eluent at a flow rate of 0.8 ml/min, electrolytically generated gradients, and suppressed conductivity detection. To analyze the HAAs in real hospital wastewater samples, C18 pretreatment cartridge was utilized to reduce samples' turbidity. Preconcentration with SPE and matrix elimination with treatment cartridges were investigated and were found to be able to obtain acceptable detection limits. Linearity, repeatability and detection limits of the above method were evaluated. The detection limits of monobromoacetic acid and dibromoacetic acid were 2.61 μg/L and 1.30 μg/L respectively, and the other three are ranging from 0.48 to 0.82 μg/L under 25-fold preconcentration. When the above optimization procedure was applied to three hospital wastewater samples with different treatment processes in Tianjin, it was found that the dichloroacetic acid is the major compound, and the growth ratios of the HAAs after disinfection by sodium hypochlorite were 91.28%, 63.61% and 79.50%, respectively.

  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. Analysis of aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography

    Institute of Scientific and Technical Information of China (English)

    Kazuaki ITO; Kazuhiko TANAKA; Jun SAKAMOTO; Kazuya NAGAOKA; Yohichi TAKAYAMA; Takashi KANAHORI; Hiroshi SUNAHARA; Tsuneo HAYASHI; Shinji SATO; Takeshi HIROKAWA

    2012-01-01

    The analysis of seven aliphatic carboxylic acids ( formic,acetic,propionic,iso-butyric,n-butyric,iso-valeric and n-valeric acid) in anaerobic digestion process waters for biogas production was examined by ion-exclusion chromatography with dilute acidic eluents (benzoic acid,perfluorobutyric acid (PFBA) and sulfuric acid) and non-suppressed conductivity/ultraviolet (UV) detection.The columns used were a styrene/divinylbenzene-based strongly acidic cation-exchange resin column ( TSKgel SCX) and a polymethacrylate-based weakly acidic cation-exchange resin column ( TSKgel Super IC-A/C ).Good separation was performed on the TSKgel SCX in shorter retention times.For the TSKgel Super IC-A/C,peak shape of the acids was sharp and symmetrical in spite of longer retention times.In addition,the mutual separation of the acids was good except for iso- and n-butyric acids.The better separation and good detection was achieved by using the two columns (TSKgel SCX and TSKgel Super IC-A/C connected in series),lower concentrations of PFBA and sulfuric acid as eluents,non-suppressed conductivity detection and UV detection at 210 nm.This analysis was applied to anaerobic digestion process waters.The chromatograms with conductivity detection were relatively simpler compared with those of UV detection.The use of two columns with different selectivities for the aliphatic carboxylic acids and the two detection modes was effective for the determination and identification of the analytes in anaerobic digestion process waters containing complex matrices.

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

    Science.gov (United States)

    Popescu (Hoştuc), Ioana-Carmen; Petru, Filip; Humelnicu, Ionel; Mateescu, Marina; Militaru, Ecaterina; Humelnicu, Doina

    2014-10-01

    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.

  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. Water ICE: Ion Exclusion Chromatography of Very Weak Acids with a Pure Water Eluent.

    Science.gov (United States)

    Liao, Hongzhu; Shelor, C Phillip; Dasgupta, Purnendu K

    2016-05-01

    Separation of ions or ionizable compounds with pure water as eluent and detecting them in a simple fashion has been an elusive goal. It has been known for some time that carbonic acid can be separated from strong acids by ion chromatography in the exclusion mode (ICE) using only water as the eluent. The practice of water ICE was shown feasible for very weak acids like silicate and borate with a dedicated element specific detector like an inductively coupled plasma mass spectrometer (ICPMS), but this is rarely practical in most laboratories. Direct conductometric detection is possible for H2CO3 but because of its weak nature, not especially sensitive; complex multistep ion exchange methods do not markedly improve this LOD. It will clearly be impractical in acids that are weaker still. By using a permeative amine introduction device (PAID, Anal. Chem. 2016 , 88 , 2198 - 2204 ) as a conductometric developing agent, we demonstrate that a variety of weak acids (silicate, borate, arsenite, cyanide, carbonate, and sulfide) cannot only be separated on an ion exclusion column, they can be sensitively detected (LODs 0.2-0.4 μM). We observe that the elution order is essentially the same as that on a nonfunctionalized poly(styrene-divinylbenzene) column using 1-10% acetonitrile as eluent and follows the reverse order of the polar surface area (PSA) of the analyte molecules. PSA values have been widely used to predict biological transport of pharmaceuticals across a membrane but never to predict chromatographic behavior. We demonstrate the application of the technique by measuring the silicate and borate depth profiles in the Pacific Ocean; the silicate results show an excellent match with results from a reference laboratory. PMID:27075932

  5. Development of Nile red-functionalized magnetic silica nanoparticles for cobalt ion sensing and entrapping

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Tao; Lv, Yanlin; Liu, Heng; Lv, Yi; Tian, Zhiyuan, E-mail: zytian@ucas.ac.cn [University of Chinese Academy of Sciences (UCAS), School of Chemistry and Chemical Engineering (China)

    2013-09-15

    A new type of hybrid nanoparticles (NPs) with combined magnetic and fluorescent properties in single particle was developed by incorporating magnetic silica NPs with highly fluorescent Nile red dyes. These NPs clearly exhibit Co{sup 2+} ion entrapping ability in aqueous milieu and Co{sup 2+}-induced fluorescence enhancement features with high selectivity owing to the Co{sup 2+}-triggered inhibition on the photoinduced electron transfer progress in the efficient fluorophore (Nile red derivative). Moreover, these dual-functional NPs display superparamagnetic features and the motion of these fluorescent NPs can be induced by the application of an external magnetic field, enabling a facile separation/removal of toxic Co{sup 2+} ion from the aqueous milieu and real-time monitoring via fluorescence measurements.

  6. Dynamic Covalent Chemistry-based Sensing: Pyrenyl Derivatives of Phenylboronic Acid for Saccharide and Formaldehyde

    Science.gov (United States)

    Chang, Xingmao; Fan, Jiayun; Wang, Min; Wang, Zhaolong; Peng, Haonan; He, Gang; Fang, Yu

    2016-01-01

    We synthesized two specially designed pyrenyl (Py) derivatives of phenylboronic acid, PSNB1 and PSNB2, of which PSNB2 self-assemble to form dynamic aggregate in methanol-water mixture (1:99, v/v) via intermolecular H-bonding and pi-pi stacking. Interestingly, the dynamic aggregate shows smart response to presence of fructose (F) as evidenced by fluorescence color change from green to blue. More interestingly, the fluorescence emission of the resulted PSNB2-F changes from blue to green with the addition of formaldehyde (FA). The reason behind is formation of a PSNB2-F dimer via FA cross-linking. Based upon the reactions as found, sensitive and fast sensing of F and FA in water was realized, of which the experimental DLs could be significantly lower than 10 μM for both analytes, and the response times are less than 1 min. It is believed that not only the materials as created may have the potential to find real-life applications but also the strategy as developed can be adopted to develop other dynamic materials. PMID:27498703

  7. Dynamic Covalent Chemistry-based Sensing: Pyrenyl Derivatives of Phenylboronic Acid for Saccharide and Formaldehyde

    Science.gov (United States)

    Chang, Xingmao; Fan, Jiayun; Wang, Min; Wang, Zhaolong; Peng, Haonan; He, Gang; Fang, Yu

    2016-08-01

    We synthesized two specially designed pyrenyl (Py) derivatives of phenylboronic acid, PSNB1 and PSNB2, of which PSNB2 self-assemble to form dynamic aggregate in methanol-water mixture (1:99, v/v) via intermolecular H-bonding and pi-pi stacking. Interestingly, the dynamic aggregate shows smart response to presence of fructose (F) as evidenced by fluorescence color change from green to blue. More interestingly, the fluorescence emission of the resulted PSNB2-F changes from blue to green with the addition of formaldehyde (FA). The reason behind is formation of a PSNB2-F dimer via FA cross-linking. Based upon the reactions as found, sensitive and fast sensing of F and FA in water was realized, of which the experimental DLs could be significantly lower than 10 μM for both analytes, and the response times are less than 1 min. It is believed that not only the materials as created may have the potential to find real-life applications but also the strategy as developed can be adopted to develop other dynamic materials.

  8. 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.

  9. Mechanism for Calcium Ion Sensing by the C2A Domain of Synaptotagmin I

    OpenAIRE

    Gauer, Jacob W.; Sisk, Ryan; Murphy, Jesse R.; Jacobson, Heathere; Sutton, R. Bryan; Gillispie, Gregory D.; Hinderliter, Anne

    2012-01-01

    The C2A domain is one of two calcium ion (Ca2+)- and membrane-binding domains within synaptotagmin I (Syt I), the identified Ca2+ sensor for regulated exocytosis of neurotransmitter. We propose that the mechanistic basis for C2A's response to Ca2+ and cellular function stems from marginal stability and ligand-induced redistributions of protein conformers. To test this hypothesis, we used a combination of calorimetric and fluorescence techniques. We measured free energies of stability by globa...

  10. Signaling Network of Environmental Sensing and Adaptation in Plants:. Key Roles of Calcium Ion

    Science.gov (United States)

    Kurusu, Takamitsu; Kuchitsu, Kazuyuki

    2011-01-01

    Considering the important issues concerning food, environment, and energy that humans are facing in the 21st century, humans mostly depend on plants. Unlike animals which move from an inappropriate environment, plants do not move, but rapidly sense diverse environmental changes or invasion by other organisms such as pathogens and insects in the place they root, and adapt themselves by changing their own bodies, through which they developed adaptability. Whole genetic information corresponding to the blueprints of many biological systems has recently been analyzed, and comparative genomic studies facilitated tracing strategies of each organism in their evolutional processes. Comparison of factors involved in intracellular signal transduction between animals and plants indicated diversification of different gene sets. Reversible binding of Ca2+ to sensor proteins play key roles as a molecular switch both in animals and plants. Molecular mechanisms for signaling network of environmental sensing and adaptation in plants will be discussed with special reference to Ca2+ as a key element in information processing.

  11. Ion chromatographic determination of dibutylphosphoric acid in nuclear fuel reprocessing streams

    International Nuclear Information System (INIS)

    A rapid method was developed for the determination of dibutylphosphoric acid (DBP), a degradation product of tributylphosphate (TBP), which is used in a solvent extraction process for recovery of uranium. DBP, along with any monobutylphosphoric acid (MBP) and phosphoric acid, are extracted from the organic phase into dilute sodium hydroxide. DBP is separated from MBP and phosphoric acid by ion chromatography (IC) and is determined on a peak height ratio basis. The method required only 30 minutes per analysis as compared to the conventional alumina column separation-colorimetric determination procedure, which requires eight hours to complete. DBP has been quantified to a lower limit of 1.5 mg/l. Relative standard deviations ranging from 5.7 to 0.4% were obtained for DBP concentrations ranging from 1.5 to 500 mg/l, respectively

  12. Synthesis of some salicylic acid derivatives and studies of their interaction with uranyl ion

    International Nuclear Information System (INIS)

    Some unsubstituted and substituted bis-derivatives of salicylic acid were synthesized and their acidity constants determined spectrophotometrically in 61.10% aqueous ethanol. The stability constants of complexes which these compounds form with the UO22+ ion were determined spectrophotometrically using the method of continuous variation under the following conditions: pH 3.58 and 3.98, 61.10% aqueous ethanol, μ=0.5 (LiCl), 25±1 degC. (author). 3 figs., 2 tabs., 8 refs

  13. Preparation of Iminodiacetic Acid-Polyethylene Glycol for Immobilized Metal Ion Affinity Partitioning

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The synthesis route was investigated and optimized for the preparation of iminodiacetic acid polyethylene glycol (IDA-PEG) for immobilized metal ion affinity partitioning in aqueous two-phaze systems. IDA PEG was synthesized from PEG in two steps by the reaction of iminodiacetic acid with a monosubetituted derivative of epichlorohydrin-activated PEG. The Cu2+ content combined with IDA-PEG was determined by atomic absorp tion spectrometry as 0.5 mol.mol-1 (PEG). Furthermore, the affinity partitioning behavior of lactate dehydrogenase in polyethylene glycol/hydroxypropyl starch aqueous two-phaze systems was studied to clarify the affinity effect of the Cu(Ⅱ)-IDA-PEG.

  14. Novel additives for the separation of organic acids by ion-pair chromatography

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper proposes the use of novel surfactant additives for the separation of organic acids by ion-pair chromatography and studies the influences of surfactants on the chromatographic separation behaviors.Researches have been carried out on both silica gel matrix and polymer supporters in order to compare the two ordinary kinds of stationary phases,and the phenomenon is similar. Separation is based on differences in the stabilities of analyte-additive complexes in solution.Retention times of analytes c...

  15. Degradation of acid red 14 by silver ion-catalyzed peroxydisulfate oxidation in an aqueous solution

    OpenAIRE

    RASOULIFARD, Mohammad Hossein; MOHAMMADI, Seied Mohammad Mahdi DOUST

    2012-01-01

    Silver ion (Ag1+)-catalyzed peroxydisulfate was studied for the degradation of acid red 14 (AR-14) in an aqueous medium. The effect of different parameters, such as temperature, peroxydisulfate concentration, and dye and Ag1+ concentrations, were investigated. Application of Ag1+-catalyzed peroxydisulfate, as an advanced oxidation process, introduces an effectual method for wastewater treatment. An accelerated reaction using S2O82- to destroy dyes can be achieved via chemical activat...

  16. nC60 deposition kinetics: the complex contribution of humic acid, ion concentration, and valence.

    Science.gov (United States)

    McNew, Coy P; LeBoeuf, Eugene J

    2016-07-01

    The demonstrated toxicity coupled with inevitable environmental release of nC60 raise serious concerns about its environmental fate and transport, therefore it is crucial to understand how nC60 will interact with subsurface materials including attached phase soil and sediment organic matter (AP-SOM). This study investigated the attachment of nC60 onto a Harpeth humic acid (HHA) coated silica surface under various solution conditions using a quartz crystal microbalance with dissipation monitoring. The HHA coating greatly enhanced nC60 attachment at low ion concentrations while hindering attachment at high ion concentrations in the presence of both mono and divalent cations. At low ion concentrations, the HHA greatly reduced the surface potential of the silica, enhancing nC60 deposition through reduction in the electrostatic repulsion. At high ion concentrations however, the reduced surface potential became less important due to the near zero energy barrier to deposition and therefore non-DLVO forces dominated, induced by compaction of the HHA layer, and leading to hindered attachment. In this manner, observed contributions from the HHA layer were more complex than previously reported and by monitoring surface charge and calculated DLVO interaction energy alongside attachment experiments, this study advances the mechanistic understanding of the variable attachment contributions from the humic acid layer. PMID:27061365

  17. Gas-Phase Amidation of Carboxylic Acids with Woodward's Reagent K Ions

    Science.gov (United States)

    Peng, Zhou; Pilo, Alice L.; Luongo, Carl A.; McLuckey, Scott A.

    2015-06-01

    Gas-phase amidation of carboxylic acids in multiply-charged peptides is demonstrated via ion/ion reactions with Woodward's reagent K (wrk) in both positive and negative mode. Woodward's reagent K, N-ethyl-3-phenylisoxazolium-3'-sulfonate, is a commonly used reagent that activates carboxylates to form amide bonds with amines in solution. Here, we demonstrate that the analogous gas-phase chemistry occurs upon reaction of the wrk ions and doubly protonated (or doubly deprotonated) peptide ions containing the carboxylic acid functionality. The reaction involves the formation of the enol ester intermediate in the electrostatic complex. Upon collisional activation, the ethyl amine on the reagent is transferred to the activated carbonyl carbon on the peptide, resulting in the formation of an ethyl amide (addition of 27 Da to the peptide) with loss of a neutral ketene derivative. Further collision-induced dissociation (CID) of the products and comparison with solution-phase amidation product confirms the structure of the ethyl amide.

  18. Amino acids and metal ions protect endothelial cells from lethal injury

    Energy Technology Data Exchange (ETDEWEB)

    Varani, J.; Ginsburg, I.; Johnson, K.J.; Gibbs, D.F.; Weinberg, J.M.; Ward, P.A. (Univ. of Michigan, Ann Arbor (United States))

    1991-03-11

    Killing of rat pulmonary artery endothelial cells by activated neutrophils is dependent on generation of hydrogen peroxide and its conversion to a highly toxic radical (presumably the hydroxyl radical) in a ferrous iron-dependent reaction. Glycine (as well as several other amino acids) is capable of inhibiting endothelial cell killing in vitro by either activated neutrophils or reagent hydrogen peroxide. Inhibition of killing is enhanced in the presence of micromolar concentrations of manganous ion (Mn2+). The combined effects of glycine and Mn2+ require concomitant presence of bicarbonate ion and is inhibited by high phosphate levels. Glycine can also protect endothelial cells from lethal injury inducted by ionomycin. There appears to be no enhancement with Mn2+, however against this form of lethal injury. The protective effects of glycine, Mn2+ and bicarbonate ion against injury by hydrogen peroxide is associated with a direct disproportionation of the hydrogen peroxide to water with little generation of molecular oxygen. Either glycine or Mn2+ alone does not have this effect. In addition to protecting endothelial cells from hydrogen peroxide-mediated injury, glycine or MN2+ is almost completely protective. Additionally, treatment of rats with concentrations of EDTA that do not by themselves induce injury greatly accentuates lung injury induced by glucose oxidase. These findings suggest that circulating amino acids in combination with Mn2+ and bicarbonate ions may contribute to the normal anti-oxidant barrier. These findings may also form the basis for a possible new therapeutic approach to oxygen radical-mediated injury.

  19. Understanding the electrolyte background for biochemical sensing with ion-sensitive field-effect transistors.

    Science.gov (United States)

    Tarasov, Alexey; Wipf, Mathias; Stoop, Ralph L; Bedner, Kristine; Fu, Wangyang; Guzenko, Vitaliy A; Knopfmacher, Oren; Calame, Michel; Schönenberger, Christian

    2012-10-23

    Silicon nanowire field-effect transistors have attracted substantial interest for various biochemical sensing applications, yet there remains uncertainty concerning their response to changes in the supporting electrolyte concentration. In this study, we use silicon nanowires coated with highly pH-sensitive hafnium oxide (HfO(2)) and aluminum oxide (Al(2)O(3)) to determine their response to variations in KCl concentration at several constant pH values. We observe a nonlinear sensor response as a function of ionic strength, which is independent of the pH value. Our results suggest that the signal is caused by the adsorption of anions (Cl(-)) rather than cations (K(+)) on both oxide surfaces. By comparing the data to three well-established models, we have found that none of those can explain the present data set. Finally, we propose a new model which gives excellent quantitative agreement with the data. PMID:23016890

  20. Polyurethane Ionophore-Based Thin Layer Membranes for Voltammetric Ion Activity Sensing.

    Science.gov (United States)

    Cuartero, Maria; Crespo, Gaston A; Bakker, Eric

    2016-06-01

    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. PMID:27187779

  1. 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.

  2. Multivalent ion-mediated nucleic acid helix-helix interactions: RNA versus DNA

    CERN Document Server

    Wu, Yuan-Yan; Zhang, Jin-Si; Zhu, Xiao-Long; Tan, Zhi-Jie

    2015-01-01

    Ion-mediated interaction is critical to the structure and stability of nucleic acids. Recent experiments suggest that the multivalent ion-induced aggregation of double-stranded (ds) RNAs and DNAs may strongly depend on the topological nature of helices, while there is still lack of an understanding on the relevant ion-mediated interactions at atomistic level. In this work, we have directly calculated the potentials of mean force (PMF) between two dsRNAs and between two dsDNAs in Cobalt Hexammine ion (Co-Hex) solutions by the atomistic molecular dynamics simulations. Our calculations show that at low [Co-Hex], the PMFs between B-DNAs and between A-RNAs are both (strongly) repulsive.However, at high [Co-Hex], the PMF between B-DNAs is strongly attractive, while those between A-RNAs and between A-DNAs are still (weakly) repulsive. The microscopic analyses show that for A-form helices, Co-Hex would become internal binding into the deep major groove and consequently cannot form the evident ion-bridge between adjac...

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

    Science.gov (United States)

    Tolokh, Igor S.; Drozdetski, Aleksander V.; Pollack, Lois; Baker, Nathan A.; Onufriev, Alexey V.

    2016-04-01

    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 binding

  4. Effects of acidity, temperature and surfactants on electrochemical behavior of V5+ ion in sulfuric acid solutions

    Institute of Scientific and Technical Information of China (English)

    易清风; 刘云清; 赵红钢; 周秀林; 刘小平; 宋和付

    2003-01-01

    The effects of sulfuric acid concentration,reaction temperature,potential-scanning rate and surfactants on electrochemical behavior of V5+ ion on platinum electrodes were investigated.In voltammetric curves of V5+ ion there are two reduction peaks corresponding to reductions of V5+ to V4+(R2)and V5+ to V3+(R1),which are irreversible and quasi-reversible processes respectively.Oxidation peak of V3+ to V5+ is intensively affected by pH values on the electrode surface and scanning-potential rates.Only stronger acidity on the electrode surface and faster scanning-potential rates can lead to appearance of this oxidation peak.The neutral surfactant(PCBE)and cationic surfactant(CTAB)retard the V5+ electroreduction.The anionic surfactant(SDS),even at a very low concentration,increases the currents of both the reduction peaks R1 and R2,and the oxidation peak involves with the oxidation of H2 to H+.

  5. ITO electrode modified by a gold ion implantation technique for direct electrocatalytic sensing of hydrogen peroxide

    International Nuclear Information System (INIS)

    We report on a simple strategy for the fabrication of gold nanoparticles (AuNPs) on an indium tin oxide substrate using a modified ion implantation method. The morphology, structure and electrochemical features of AuNPs were characterized by atomic force microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode has a large electrochemically active surface and enables strong loading with cytochrome c (Cyt c) proteins. It undergoes enhanced electron transfer at uncompromised electrochemical activity, and also displays good stability and repeatability. The immobilized Cyt c exhibits good electrocatalytic activity towards hydrogen peroxide (H2O2), with a linear relationship between the catalytic current during differential pulse voltammetry and the concentration of H2O2 in the 0.05 μM to 0.2 μM range. The detection limit (S/N = 3) is 0. 01 μM. (author)

  6. 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.

  7. Study on elution ability of salicylic acid on ion exchange resins in supercritical carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    Ping YUAN; Jianguo CAI; Junjie GONG; Xiu DENG

    2009-01-01

    The elution ability of salicylic acid on ion exchange resins in supercritical carbon dioxide has been studied. Some factors influencing elution recovery,including entrainer, temperature, pressure and the flow rate of supercritical fluid CO2 are discussed in this work.The addition of a small amount of entrainer, such as ethanol, triethanolamine and their mixture to supercritical CO2 can cause dramatic effects on the elution ability. The results show that the salicylic acid can be only slightly eluted from the resin with supercritical CO2 alone with temperatures ranging from 307.15 to 323.15K and pressures ranging from 10 to 30MPa. Meanwhile, with the same T, P conditions, 40.58% and 73.08% salicylic acid can be eluted from the ion exchange resin with ethanol and ethanol + triethanolamine as the entrainer, respec-tively. An improved PR equation of state with VDWl mixing rules is used to calculate the elution recovery of salicylic acid in supercritical CO2 and the results agree well with the experimental data.

  8. Investigation of complexing reactions of terbium(3) ions with anions of salicylic and 5-sulfosalicylic acids in aqueous solutions

    International Nuclear Information System (INIS)

    Complexing of terbium(3) ions with anions of salicylic and 5-sulfosalicylic acids was investigated by luminescence-kinetic method. Values of stability and dissociation constants of formed complexes were obtained

  9. Determination of uric acid in human urine by ion chromatography with conductivity detector

    Institute of Scientific and Technical Information of China (English)

    Fu Yong Zhao; Zong Hua Wang; Hui Wang; Rui Zhao; Ming Yu Ding

    2011-01-01

    A simple, fast, precise and eco-friendly analytical method for the determination of uric acid (UA) in human urine by ion chromatography (IC) was established. The sample pretreatment was not required, only needed centrifugation and filtration. The separation was carried out on a cation exchange column with 2.0 mmol/L nitric acid as mobile phase at the flow-rate 1.0 mL/min. A non-suppressed conductivity detector was used. The IC analysis time for one run was within 10 min under the optimized IC condition. The detection limits were 0.5 μg/L(S/N = 3) for uric acid. The recovery was 100.1 % while the relative standard deviation (RSD) was 1.8% from 10 measurements.

  10. 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.

  11. The reduction process of phytic acid-silver ion system: A pulse radiolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Ravi [Radiation and Photochemistry Division, Chemistry Group, Bhabha Atomic Research Center, Mumbai 400 085 (India)]. E-mail: rjudrin@yahoo.com; Mukherjee, Tulsi [Radiation and Photochemistry Division, Chemistry Group, Bhabha Atomic Research Center, Mumbai 400 085 (India)

    2007-05-15

    Reduction of silver ion in a silver-phytic acid (1:1 ratio) system has been studied using pulse radiolysis technique. Time-resolved transformation of the intermediates, Ag{sup +{yields}}Ag{sup 0{yields}}Ag{sub 2} {sup +{yields}}Ag{sub 3} {sup 2+}, has been clearly observed in the reduction of silver-phytic acid (1:1) system. The effect of phytic acid on the formation and decay of initial silver clusters has been also studied. The surface plasmon absorption band of stable silver nanoparticle (410 nm) and dynamic light scattering technique has been used to characterize the nanoparticles and measure the average size (R {sub av}=100 nm)

  12. Interaction study of amino acids and the peptide aspartame with lanthanide (III) ions

    International Nuclear Information System (INIS)

    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)

  13. Studies on low energy ion beam mediated DNA transformation of 2-keto-L-gulonic acid strains

    International Nuclear Information System (INIS)

    The biological effect of 2-keto-L-gulonic acid strains and their DNA implanted by low energy ions have been studied. Through low energy ion beam-mediated transferring foreign DNA into 2-KLG strain, two gene recombination strains were obtained. From this, a new research system-delivery of foreign DNA into microorganism via ion beam was established, offering a new way to construct genetically engineered microorganism. (authors)

  14. Enhancement of L(+)-Lactic Acid Production of Immobilized Rhizopus Oryzae Implanted by Ion Beams

    Institute of Scientific and Technical Information of China (English)

    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 × 1015 ions/cm2. 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~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.

  15. Chemical reaction calculation simulation of redox behavior of metal ions and the like in the nitric acid solution

    International Nuclear Information System (INIS)

    It is known that corrosion rate of stainless steel in nitric acid solution is affected by the valence change of oxidizing metallic ions. In this study, we conducted redox reaction analyses using chemical reaction calculation model to clarify the mechanism of valence change. We obtained that the oxidization of metallic ions in the solution is not only caused by nitric acid but also nitrogen oxides. (author)

  16. The Crystal Structure of Burkholderia cenocepacia DfsA Provides Insights into Substrate Recognition and Quorum Sensing Fatty Acid Biosynthesis.

    Science.gov (United States)

    Spadaro, Francesca; Scoffone, Viola C; Chiarelli, Laurent R; Fumagalli, Marco; Buroni, Silvia; Riccardi, Giovanna; Forneris, Federico

    2016-06-14

    Burkholderia cenocepacia is a major concern among respiratory tract infections in cystic fibrosis patients. This pathogen is particularly difficult to treat because of its high level of resistance to the clinically relevant antimicrobial agents. In B. cenocepacia, the quorum sensing cell-cell communication system is involved in different processes that are important for bacterial virulence, such as biofilm formation and protease and siderophore production. Targeting the enzymes involved in this process represents a promising therapeutic approach. With the aim of finding effective quorum sensing inhibitors, we have determined the three-dimensional structure of B. cenocepacia diffusible factor synthase A, DfsA. This bifunctional crotonase (dehydratase/thioesterase) produces the characteristic quorum sensing molecule of B. cenocepacia, cis-2-dodecenoic acid or BDSF, starting from 3-hydroxydodecanoyl-acyl carrier protein. Unexpectedly, the crystal structure revealed the presence of a lipid molecule in the catalytic site of the enzyme, which was identified as dodecanoic acid. Our biochemical characterization shows that DfsA is able to use dodecanoyl-acyl carrier protein as a substrate, demonstrating that dodecanoic acid, the product of this reaction, is released very slowly from the DfsA active site, therefore acting as a DfsA inhibitor. This molecule shows an unprecedented conformational arrangement inside the DfsA active site. In contrast with previous hypotheses, our data illustrate how DfsA and closely related homologous enzymes can recognize long hydrophobic substrates without large conformational changes or assistance by additional regulator molecules. The elucidation of the substrate binding mode in DfsA provides the starting point for structure-based drug discovery studies targeting B. cenocepacia quorum sensing-assisted virulence. PMID:27198181

  17. [Determination of organic acids and inorganic anions by gradient ion chromatography].

    Science.gov (United States)

    Liu, Z; Liu, K; Shen, D; Song, Q; Mou, S; Feng, Y

    1997-07-01

    The chromatographic conditions for separation and detection of organic acids and inorganic anions by gradient ion chromatography with suppressed conductivity detection were studied. The optimized gradient programs were established. Ion chromatography were performed with a DX-100 chromatograph (DIONEX). The separation column is IonPac-AS11. Compared with NaHCO3/Na2CO3 and Na2B4O7, NaOH was the optimal eluent. The effect of organic modifier was also studied. Among methanol, 2-propanol and acetonitrile, methanol can make ion pairs such as malate and succinate, malonate and tartrate gaining baseline resolution. By using ion exchange separation, Cl-, NO3-, malate, succinate, malonate, tartrate, SO4(2-), oxalate were eluted between 5 mmol/L NaOH-16% CH3OH and 10 mmol/L NaOH-16% CH3OH in 25 min. A mobile phase composed of 30 mmol/L NaOH, 50% CH3OH and D.I. water was chosen to elute two groups of organic acids and inorganic anions: (1) quinate, formate, Cl-, malate, malonate, oxalate, citrate, isocitrate, aconitate; (2) lactate, Cl-, SO4(2-), tartrate, PO4(3-), citrate, isocitrate, aconitate. The detection limits (S/N = 3) were 0.1625 (quinate), 0.0691 (formate), 0.0115 (Cl-), 0.0886 (malate), 0.0591 (malonate), 0.0263 (oxalate), 0.1147 (citrate), 0.2017 (isocitrate), 0.3656 (cis-aconitate), 0.1045 (trans-aconitate), 0.1950 (lactate), 0.0729 (tartrate), 0.0224 (SO4(2-)) and 0.0692 (PO4(3-)) mg/L. The relative standard deviations were lower than 11.9% (n = 7) and the correlation coefficients ranged from 0.9212 for Cl- to 0.9999 for formate. The method was applied to determine the organic acids and inorganic anions of beverages and citric acids fermenting-medium. The results were satisfactory.

  18. Acrylic acid grafted cellulosic Luffa cylindrical fiber for the removal of dye and metal ions.

    Science.gov (United States)

    Gupta, Vinod Kumar; Agarwal, Shilpi; Singh, Prerna; Pathania, Deepak

    2013-10-15

    Acrylic acid grafted cellulosic Luffa cylindrical fiber was utilized for the removal of methylene blue and metal ions from the water system using batch process. The grafted sample used was found to demonstrate a maximum grafting efficiency of 90.8% under concentrations of 0.432×10(-3) mol/L, temperature of 35 °C, time of 60 min and pH of 7.0 respectively. The remarkable improvement in thermal properties of the grafted sample was observed. The formation of new bands in FTIR spectra of grafted sample confirmed the grafting of acrylic acid onto the cellulosic fiber. The maximum adsorption capacity of dye onto adsorbent was observed to be 62.15 mg g(-1) at 175 min. A maximum removal of 45.8% was observed for Mg(2+) as compared to other metal ions. High values of correlation coefficient for methylene blue (0.995) and metal ions such as Mg(2+) (0.996), Ni(2+) (0.995), Zn(2+) (0.996) confirmed the applicability of Langmuir isotherm that assumed a monolayer coverage and uniform activity distribution on the adsorbent surface.

  19. Radiation synthesis of chitosan beads grafted with acrylic acid for metal ions sorption

    Energy Technology Data Exchange (ETDEWEB)

    Benamer, S., E-mail: benamers@yahoo.fr [Division of Nuclear Applications, Centre de Recherche Nucleaire d' Alger, BP-399 Alger-Gare (Algeria); Mahlous, M.; Tahtat, D.; Nacer-Khodja, A.; Arabi, M. [Division of Nuclear Applications, Centre de Recherche Nucleaire d' Alger, BP-399 Alger-Gare (Algeria); Lounici, H.; Mameri, N. [Ecole Nationale Polytechnique d' El-Harrach Alger (Algeria)

    2011-12-15

    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.

  20. Radiation synthesis of chitosan beads grafted with acrylic acid for metal ions sorption

    International Nuclear Information System (INIS)

    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.

  1. Single-indicator-based Multidimensional Sensing: Detection and Identification of Heavy Metal Ions and Understanding the Foundations from Experiment to Simulation.

    Science.gov (United States)

    Leng, Yumin; Qian, Sihua; Wang, Yuhui; Lu, Cheng; Ji, Xiaoxu; Lu, Zhiwen; Lin, Hengwei

    2016-01-01

    Multidimensional sensing offers advantages in accuracy, diversity and capability for the simultaneous detection and discrimination of multiple analytes, however, the previous reports usually require complicated synthesis/fabrication process and/or need a variety of techniques (or instruments) to acquire signals. Therefore, to take full advantages of this concept, simple designs are highly desirable. Herein, a novel concept is conceived to construct multidimensional sensing platforms based on a single indicator that has capability of showing diverse color/fluorescence responses with the addition of different analytes. Through extracting hidden information from these responses, such as red, green and blue (RGB) alterations, a triple-channel-based multidimensional sensing platform could consequently be fabricated, and the RGB alterations are further applicable to standard statistical methods. As a proof-of-concept study, a triple-channel sensing platform is fabricated solely using dithizone with assistance of cetyltrimethylammonium bromide (CTAB) for hyperchromicity and sensitization, which demonstrates superior capabilities in detection and identification of ten common heavy metal ions at their standard concentrations of wastewater-discharge of China. Moreover, this sensing platform exhibits promising applications in semi-quantitative and even quantitative analysis individuals of these heavy metal ions with high sensitivity as well. Finally, density functional theory calculations are performed to reveal the foundations for this analysis. PMID:27146105

  2. Single-indicator-based Multidimensional Sensing: Detection and Identification of Heavy Metal Ions and Understanding the Foundations from Experiment to Simulation

    Science.gov (United States)

    Leng, Yumin; Qian, Sihua; Wang, Yuhui; Lu, Cheng; Ji, Xiaoxu; Lu, Zhiwen; Lin, Hengwei

    2016-05-01

    Multidimensional sensing offers advantages in accuracy, diversity and capability for the simultaneous detection and discrimination of multiple analytes, however, the previous reports usually require complicated synthesis/fabrication process and/or need a variety of techniques (or instruments) to acquire signals. Therefore, to take full advantages of this concept, simple designs are highly desirable. Herein, a novel concept is conceived to construct multidimensional sensing platforms based on a single indicator that has capability of showing diverse color/fluorescence responses with the addition of different analytes. Through extracting hidden information from these responses, such as red, green and blue (RGB) alterations, a triple-channel-based multidimensional sensing platform could consequently be fabricated, and the RGB alterations are further applicable to standard statistical methods. As a proof-of-concept study, a triple-channel sensing platform is fabricated solely using dithizone with assistance of cetyltrimethylammonium bromide (CTAB) for hyperchromicity and sensitization, which demonstrates superior capabilities in detection and identification of ten common heavy metal ions at their standard concentrations of wastewater-discharge of China. Moreover, this sensing platform exhibits promising applications in semi-quantitative and even quantitative analysis individuals of these heavy metal ions with high sensitivity as well. Finally, density functional theory calculations are performed to reveal the foundations for this analysis.

  3. Molecule modification andmass deposition induced bythe implantation of lowenergy Fe+ ion beamsinto amino acids

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Fe+ ion beams with the energy of 110 keV were implanted into films of L(+)-cysteine (HSCH2CH(NH2)COOH). One of the single crystals grown in hydrochloric acid solution with the implanted samples through slow evaporation was structurally characterized by the X-ray crystallography. The crystal is monoclinic, space group C2, with a = 1.8534(4) nm, b = 0.5234(1) nm, c = 0.7212(1) nm, β= 103.72°, V = 0.67965(3) nm3, Z = 4, F(000) = 144.0, Dclac = 1.763 g@cm-3, μ(MoKα) = 1.06 mm-1, T = 293(2) K. R = 0.0379, wR = 0.0835 for 660 observed reflections (I > 2σ(I)). The structural formula of the crystal compound is (CH2CH(NH2)NO2)ClFe (Mr = 180.38 u). Products of heavy ion beam irradiation were purified and it was directly confirmed that the implanted Fe+ ions had been deposited in the novel molecules. The same doses of Fe+ ion beams of the same energy were implanted into films of L(+)-cysteine hydrochloride monohydrate. FTIR spectroscopy of the implanted samples proved that some of the original molecules were seriously damaged and significant modifications were induced.

  4. Removal of textile dyes and metallic ions using polyelectrolytes and macroelectrolytes containing sulfonic acid groups.

    Science.gov (United States)

    Caldera Villalobos, M; Peláez Cid, A A; Herrera González, Ana M

    2016-07-15

    This work reports the removal of textile dyes and metallic ions by means of adsorption and coagulation-flocculation using two polyelectrolytes and two macroelectrolytes containing sulfonic acid groups. The adsorption of textile dyes was studied in aqueous solutions containing cationic dyes and in wastewater containing a vat dye. Also, removal of vat and naphthol dyes was studied using the process of coagulation-flocculation. The results show these materials possess elevated adsorption capacity, and they accomplished removal rates above 97% in aqueous solutions. The removal of the vat dye improved the quality of the wastewater notably, and an uncolored effluent was obtained at the end of the treatment. The treatment using adsorption decreased the values for coloration, conductivity, suspended solids, and pH. The removal of vat and naphthol dyes by means of coagulation-flocculation was studied as well, and removal rates of 90% were obtained. The polyelectrolytes and macroelectrolytes also proved effective in the adsorption of metallic ions in wastewater. The treatment using adsorption accomplished high removal rates of metallic ions, and it showed greater selectivity towards Cu(2+), Fe(3+) and Pb(2+). A decrease in the content of solids as well as the values for COD and conductivity was observed in the wastewater as well. The analyses of FT-IR indicated that cationic dyes and metallic ions were chemisorbed by means of ionic exchange. PMID:27082258

  5. Nanoparticles formed by complexation of poly-gamma-glutamic acid with lead ions

    International Nuclear Information System (INIS)

    The present investigation describes the preparation and characterization of novel biodegradable nanoparticles based on complexation of poly-gamma-glutamic acid (γ-PGA) with bivalent lead ion. The prepared nano-systems were stable in aqueous media at low pH, neutral and mild alkaline conditions. The particle size and the size of the complexes were identified by dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements. It was found that the size of the complexes depended on the pH and concentrations of γ-PGA and lead ions. Particle sizes measured by TEM revealed that at low concentrations, nanosized particles were formed, however, at high concentrations of γ-PGA and lead ions, the formation of large aggregates with a broad size distribution was promoted. The size of individual particles was in the range of 40-100 nm measured by TEM. The results from the DLS measurements showed that the low and high pH values in mixtures with high concentrations of γ-PGA and Pb2+ ions favored the growth of large complexes. The γ-PGA nanoparticles, composed of a biodegradable biomaterial with high flocculating and heavy metal binding activity, may be useful for various water treatment applications

  6. Nanoparticles formed by complexation of poly-gamma-glutamic acid with lead ions

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, Magdolna [Departments of Colloid and Environmental Chemistry, University of Debrecen, H-4010 Debrecen (Hungary); Kjoniksen, Anna-Lena [Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo (Norway); Molnar, Reka M. [Departments of Colloid and Environmental Chemistry, University of Debrecen, H-4010 Debrecen (Hungary); Hartmann, John F. [ElizaNor Polymer LLC, Princeton Junction, NJ 08550 (United States); Daroczi, Lajos [Solid State Physics, University of Debrecen, H-4010 Debrecen (Hungary); Nystroem, Bo [Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo (Norway); Borbely, Janos [Departments of Colloid and Environmental Chemistry, University of Debrecen, H-4010 Debrecen (Hungary); BBS Nanotechnology Ltd., P.O. Box 12, H-4225 Debrecen 16 (Hungary)], E-mail: jborbely@delfin.unideb.hu

    2008-05-30

    The present investigation describes the preparation and characterization of novel biodegradable nanoparticles based on complexation of poly-gamma-glutamic acid ({gamma}-PGA) with bivalent lead ion. The prepared nano-systems were stable in aqueous media at low pH, neutral and mild alkaline conditions. The particle size and the size of the complexes were identified by dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements. It was found that the size of the complexes depended on the pH and concentrations of {gamma}-PGA and lead ions. Particle sizes measured by TEM revealed that at low concentrations, nanosized particles were formed, however, at high concentrations of {gamma}-PGA and lead ions, the formation of large aggregates with a broad size distribution was promoted. The size of individual particles was in the range of 40-100 nm measured by TEM. The results from the DLS measurements showed that the low and high pH values in mixtures with high concentrations of {gamma}-PGA and Pb{sup 2+} ions favored the growth of large complexes. The {gamma}-PGA nanoparticles, composed of a biodegradable biomaterial with high flocculating and heavy metal binding activity, may be useful for various water treatment applications.

  7. Separation of metal ions by anion exchange in mixtures of hydrochloric acid and hydrofluoric acid

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. 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.

  9. Polymeric supported sorbents for decreasing hazardous metal ions content in wet process phosphoric acid

    International Nuclear Information System (INIS)

    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 HNO3 . 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

  10. Adsorption of uranium ions by crosslinked polyester resin functionalized with acrylic acid from aqueous solutions

    International Nuclear Information System (INIS)

    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 (ΔHo), entropy (ΔSo) and free energy change (ΔGo) 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)

  11. Colorimetric Detection of Cadmium Ions Using DL-Mercaptosuccinic Acid-Modified Gold Nanoparticles.

    Science.gov (United States)

    Chen, Na; Chen, Jun; Yang, Jing-Hua; Bai, Lian-Yang; Zhang, Yu-Ping

    2016-01-01

    A colorimetric assay has been developed for detection of Cd²⁺ utilizing DL-mercaptosuccinic acid-modified gold nanoparticles (MSA-AuNPs). The method showed good selectivity for Cd²⁺ over other metal ions. As a result, the linear relationships (r > 0.9606) between concentration 0.07 mM and 0.20 mM for cadmium ion were obtained. The detection limit was as low as 0.07 mM by the naked eye. The effect of pH on the aggregation was optimized. The MSA-AuNPs probe could be used to detect Cd²⁺ in an aqueous solution based on the aggregation-induced color change of MSA-AuNPs. PMID:27398533

  12. One-pot electrochemical synthesis of functionalized fluorescent carbon dots and their selective sensing for mercury ion

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Yuxin; Lu, Qiujun; Deng, Jianhui; Li, Haitao; Zhang, Youyu, E-mail: zhangyy@hunnu.edu.cn

    2015-03-25

    Highlights: • One-pot electrochemical synthesis of functionalized carbon dots (C-Dots). • The C-Dots can serve as a fluorescent probe for sensitive detection of Hg{sup 2+}. • The detection limit for Hg{sup 2+} is 3.3 nM. • The sensor is successfully applied to Hg{sup 2+} determination in real samples. - Abstract: We propose a simple, economical, and one-pot method to synthesize water-soluble functionalized fluorescent carbon dots (C-Dots) through electrochemical carbonization of sodium citrate and urea. The as-prepared C-Dots have good photostability and exhibit a high quantum yield of 11.9%. The sizes of the C-Dots are mainly distributed in the range of 1.0–3.5 nm with an average size of 2.4 nm. It has been further used as a novel label-free sensing probe for selective detection of Hg{sup 2+} ions with detection limit as low as 3.3 nM. The detection linear range is 0.01–10 μM. The as-prepared C-Dots are also successfully applied for the determination of Hg{sup 2+} in real water samples.

  13. Effects of pH, organic acids, and inorganic ions on lead desorption from soils

    International Nuclear Information System (INIS)

    The desorption characteristics of lead in two variable charge soils (one developed from Arenaceous rock (RAR) and the other derived from Quaternary red earths (REQ)) were studied, and the effects of pH value, organic acid, and competitive ions were examined. Desorption of Pb2+ decreased from nearly 100.0 to 20.0% within pH 1.0-4.0 in both soils, and then the decrease diminished at pH > 4.0. Organic ligands at relatively low concentrations (≤10-3 mol L-1) slightly inhibited Pb2+ desorption, but enhanced Pb2+ desorption at higher concentrations. In this study, citric acid or acetic acid at higher concentrations (>10-3 mol L-1) had the greatest improvement of Pb2+ desorption, followed by malic acid; and the smallest was oxalic acid. Desorption of the adsorbed Pb2+ increased greatly with increasing concentrations of added Cu2+ or Zn2+. Applied Cu2+ increased Pb2+ desorption more than Zn2+ at the same loading. - The adsorption-desorption process is a basic and important reaction in soils controlling Pb2+ mobility and bioavailability

  14. 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.

  15. 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)

    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 (Hg2+), herein we construct a new DNA-based sensor for sensitive electrochemical monitoring of Hg2+ 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, Hg2+ ion was intercalated into the DNA polyion complex membrane based on T–Hg2+–T coordination chemistry. The chelated Hg2+ ion could induce the formation of gold amalgamation, which could catalyze the p-nitrophenol with the aid of NaBH4 and Ru(NH3)63+ for cycling signal amplification. Experimental results indicated that the electronic signal of our system increased with the increasing Hg2+ level in the sample, and has a detection limit of 0.02 nM with a dynamic range of up to 1000 nM Hg2+. The strategy afforded exquisite selectivity for Hg2+ against other environmentally related metal ions. In addition, the methodology was evaluated for the analysis of Hg2+ in spiked tap-water samples, and the recovery was 87.9–113.8%

  16. 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...

  17. SYNTHESIS OF 2—HYDROXYETHYL ACRYLATE BY USING STRONG ACIDIC CATION ION EXCHANGE RESIN AS CATALYST

    Institute of Scientific and Technical Information of China (English)

    GAODabin

    1992-01-01

    2-Hydroxyethyl acrylate is synthesized from acrylic acid and ethylene glycol under a simple and mild condition by using strong acidic cation ion exchange resin as a catalyst,which could be recycled as long as 10 times with high activation.

  18. 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

  19. Dietary fatty acid composition is sensed by the NLRP3 inflammasome: omega-3 fatty acid (DHA) prevents NLRP3 activation in human macrophages.

    Science.gov (United States)

    Martínez-Micaelo, N; González-Abuín, N; Pinent, M; Ardévol, A; Blay, M

    2016-08-10

    The Nod-like receptor protein 3 (NLRP3) inflammasome is considered to be a pivotal host platform responsible for sensing of exogenous and endogenous danger signals, including those generated as a result of metabolic dysregulation, and for the subsequent, IL-1β-mediated orchestration of inflammatory and innate immunity responses. In this way, although the molecular link between diet-induced obesity and inflammasome activation is still unclear, free fatty acids (FFA) have been proposed as a triggering event. We report that dietary fatty acid (FA) composition is sensed by the NLRP3 inflammasome in human macrophages. For this purpose, we have analysed three roles of FA supplementation: as a priming signal for ATP-activated macrophages, in determining where the administration of dietary FAs interferes with LPS-mediated inflammasome activation and by inducing inflammasome activation per se. In this study, we confirm that saturated (SFAs) activated the NLRP3 inflammasome and stimulated the secretion of the IL-1β cytokine, while PUFAs were mainly inhibitors. Moreover, in general, DHA (n-3 PUFA) was more effective in preventing inflammasome activation than arachidonic acid (n-6 PUFA). PMID:27405925

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

    Energy Technology Data Exchange (ETDEWEB)

    Tolokh, Igor S.; Drozdetski, Aleksander; Pollack, Lois; Baker, Nathan A.; Onufriev, Alexey

    2016-04-21

    We present a semi-quantitative model of condensation of short nucleic acid (NA) duplexes in- duced by tri-valent cobalt 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. The duplex aggregation free energy is de- composed into attraction and repulsion components represented by simple analytic expressions. The source of the short-range attraction between NA duplexes in the aggregated phase is the in- teraction of CoHex ions in the overlapping regions of the “external” shells with the oppositely charged duplexes. The attraction depends on CoHex binding affinity to the “external” shell of nearly neutralized duplex and the number of ions in the shell overlapping volume. For a given NA duplex sequence and structure, these parameters are estimated from molecular dynamics simula- tion. The attraction is opposed by the residual repulsion of nearly neutralized duplexes as well as duplex configurational entropy loss upon aggregation. 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 conden- sation. The model predicts that, in contrast to DNA, RNA duplexes may condense into tighter packed aggregates with a higher degree of duplex neutralization. The model also predicts that longer NA fragments will condense easier 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 binding shells”.

  1. Ion flotation of uranium contained in industrial phosphoric acid with collector recycling

    International Nuclear Information System (INIS)

    Uranium has been recovered from wet-process phosphoric acid (30% P2O5) 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)

  2. Electrochemical synthesis of FeS{sub 2} thin film: An effective material for peroxide sensing and terephthalic acid degradation

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Sumanta [Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103 WB (India); Mondal, Palash; Tripathi, Subhankar [Department of Chemistry, Vivekananda Mahavidyalaya, Burdwan, 713103 WB (India); Mondal, Anup [Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103 WB (India); Chakraborty, Biswajit, E-mail: biswajitmailbag@gmail.com [Department of Chemistry, Vivekananda Mahavidyalaya, Burdwan, 713103 WB (India)

    2015-10-15

    Electrochemically FeS{sub 2} thin films have been synthesized on ITO substrates at room temperature (25 °C). UV–Vis, X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) were used for the characterization of nanostructure FeS{sub 2} thin films. Two probe I–V measurements convey that the material is p type and a p-n junction (diode) was found to be developed between FeS{sub 2} and ITO layer. Cyclic voltametry study shows that FeS{sub 2}/ITO electrode facilitates the reduction of hydrogen peroxide and exhibits excellent electro-catalytic activity towards its sensing. Photocatalytic study reveals that the synthesized thin films are also efficient to degrade terephthalic acid (TA). - Graphical abstract: Electrochemically FeS{sub 2} thin films have been synthesized on ITO substrate. The synthesized material is effective for the reduction of H{sub 2}O{sub 2} and the sensitivity of the material is strongly dependent on pH and temperature. Photocatalytic study reveals that the material is quite effective towards decomposition of terephthalic acid. These results indicate that the material can play a dual role as pollutant cleanup for environmental interest. - Highlights: • Electrochemically FeS{sub 2} thin films are synthesized. • The material is effective to sense the H{sub 2}O{sub 2} and degrade terephthalic acid. • It plays a dual role as pollutant cleanup for environmental interest.

  3. Colorimetric sensor array based on gold nanoparticles and amino acids for identification of toxic metal ions in water.

    Science.gov (United States)

    Sener, Gulsu; Uzun, Lokman; Denizli, Adil

    2014-01-01

    A facile colorimetric sensor array for detection of multiple toxic heavy metal ions (Hg(2+), Cd(2+), Fe(3+), Pb(2+), Al(3+), Cu(2+), and Cr(3+)) in water is demonstrated using 11-mercaptoundecanoic acid (MUA)-capped gold nanoparticles (AuNPs) and five amino acids (lysine, cysteine, histidine, tyrosine, and arginine). The presence of amino acids (which have functional groups that can form complexes with metal ions and MUA) regulates the aggregation of MUA-capped particles; it can either enhance or diminish the particle aggregation. The combinatorial colorimetric response of all channels of the sensor array (i.e., color change in each of AuNP and amino acid couples) enables naked-eye discrimination of all of the metal ions tested in this study with excellent selectivity. PMID:25330256

  4. Ion Chromatography Based Urine Amino Acid Profiling Applied for Diagnosis of Gastric Cancer

    Directory of Open Access Journals (Sweden)

    Jing Fan

    2012-01-01

    Full Text Available Aim. Amino acid metabolism in cancer patients differs from that in healthy people. In the study, we performed urine-free amino acid profile of gastric cancer at different stages and health subjects to explore potential biomarkers for diagnosing or screening gastric cancer. Methods. Forty three urine samples were collected from inpatients and healthy adults who were divided into 4 groups. Healthy adults were in group A (n=15, early gastric cancer inpatients in group B (n=7, and advanced gastric cancer inpatients in group C (n=16; in addition, two healthy adults and three advanced gastric cancer inpatients were in group D (n=5 to test models. We performed urine amino acids profile of each group by applying ion chromatography (IC technique and analyzed urine amino acids according to chromatogram of amino acids standard solution. The data we obtained were processed with statistical analysis. A diagnostic model was constructed to discriminate gastric cancer from healthy individuals and another diagnostic model for clinical staging by principal component analysis. Differentiation performance was validated by the area under the curve (AUC of receiver-operating characteristic (ROC curves. Results. The urine-free amino acid profile of gastric cancer patients changed to a certain degree compared with that of healthy adults. Compared with healthy adult group, the levels of valine, isoleucine, and leucine increased (P<0.05, but the levels of histidine and methionine decreased (P<0.05, and aspartate decreased significantly (P<0.01. The urine amino acid profile was also different between early and advanced gastric cancer groups. Compared with early gastric cancer, the levels of isoleucine and valine decreased in advanced gastric cancer (P<0.05. A diagnosis model constructed for gastric cancer with AUC value of 0.936 tested by group D showed that 4 samples could coincide with it. Another diagnosis model for clinical staging with an AUC value of 0.902 tested by

  5. Computational probes into the conceptual basis of silver ion chromatography: I. Silver(I) ion complexes of unsaturated fatty acids and esters

    NARCIS (Netherlands)

    Damyanova, B.; Momtchilova, S.; Bakalova, S.; Zuilhof, H.; Christie, W.W.; Kaneti, J.

    2002-01-01

    Silver ion chromatography of unsaturated fatty acid derivatives can be described satisfactorily by the suggestion of Ag(I) complexation with more than a single bonding site of esters of the 18:1, 18:2, etc. series (that is, one, two, etc. methylene-interrupted double bonds in the C18 hydrocarbon cha

  6. 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.

  7. Regulation of ion homeostasis by aminolevulinic acid in salt-stressed wheat seedlings

    Science.gov (United States)

    Türk, Hülya; Genişel, Mucip; Erdal, Serkan

    2016-04-01

    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+/Na+ ratio was reduced by salt stress, ALA application changed this ratio in favor of K+. 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.

  8. The role of G-protein-coupled receptor 120 in fatty acids sensing in chicken oral tissues.

    Science.gov (United States)

    Sawamura, Ryo; Kawabata, Yuko; Kawabata, Fuminori; Nishimura, Shotaro; Tabata, Shoji

    2015-03-01

    Clarification of the mechanism of chickens' taste sense will provide meaningful information for creating and improving new feedstuff for chickens, because the character of taste receptors in oral tissues affects feeding behavior in animals. Although fatty acids are partly recognized via G-protein coupled receptor 120 (GPR120) for fat taste in mammalian oral tissues, the fat taste receptor of chickens has not been elucidated. Here we cloned chicken GPR120 (cGPR120) from the chicken palate, which contains taste buds. By using Ca(2+) imaging methods, we identified oleic acid and linoleic acid as cGPR120 agonists. Interestingly, in a behavioral study the chickens preferred corn oil-rich feed over mineral oil (control oil)-rich feed. Because corn oil contains high amounts of oleic acid and linoleic acid, this result was thought to be reasonable. Taken together, the present results suggest that cGPR120 is one of the functional fat taste receptors in chickens.

  9. An aldehyde group-based P-acid probe for selective fluorescence turn-on sensing of cysteine and homocysteine.

    Science.gov (United States)

    Yang, Chunlei; Wang, Xiu; Shen, Lei; Deng, Wenping; Liu, Haiyun; Ge, Shenguang; Yan, Mei; Song, Xianrang

    2016-06-15

    A highly sensitive and selective turn on fluorescent probe P-acid-aldehyde (P-CHO) is developed for the determination of cysteine (Cys) and homocysteine (Hcy). The probe is designed and synthesized by incorporating the specific functional group aldehyde group for thiols into a stable π-conjugated material 4,4'-(2,5-dimethoxy-1,4-phenylene) bis(ethyne-2,1-diyl) dibenzoic acid (P-acid). The probe fluorescence is quenched through donor photoinduced electron transfer (d-PET) between the fluorophore (P-acid) and the recognition group (aldehyde group). In the presence of thiols, Cys and Hcy can selectively react with aldehyde group of the probe because the inhibition of d-PET between fluorophore and recognition group. Therefore, a turn-on fluorescent sensor was established for the fluorescence recovery. Under the optimized conditions, the fluorescence response of probe is directly proportional to the concentration of Cys in the range of 4-95 NM L(-1), with a detection limit 3.0 nM. In addition, the sensing system exhibits good selectively toward Cys and Hcy in the presence of other amino acids. It has been successfully applied for bioimaging of Cys and Hcy in living cells with low cell toxicity.

  10. High performance ion chromatography of haloacetic acids on macrocyclic cryptand anion exchanger.

    Science.gov (United States)

    Bruzzoniti, Maria Concetta; De Carlo, Rosa Maria; Horvath, Krisztian; Perrachon, Daniela; Prelle, Ambra; Tófalvi, Renáta; Sarzanini, Corrado; Hajós, Péter

    2008-04-11

    A new high performance ion chromatographic method has been developed for the separation of the nine chlorinated-brominated haloacetic acids (HAAs) that are the disinfection by-products of chlorination of drinking water, using a macrocycle-based adjustable-capacity anion-exchange separator column (IonPac Cryptand A1). A gradient method based on theoretical and experimental considerations has been optimized in which 10 mM NaOH-LiOH step gradient was performed at the third minute of the analysis. The optimized method allowed us to separate the nine HAAs and seven possibly interfering inorganic anions in less than 25 min with acceptable resolution. The minimum concentrations detectable for HAAs were between 8.0 (MBA) and 210 (TBA) microg L(-1), with linearity included between 0.9947 (TBA) and 0.9998 (MBA). To increase sensitivity, a 25-fold preconcentration step on a reversed phase substrate (LiChrolut EN) has been coupled. Application of this method to the analysis of haloacetic acids in real tap water samples is illustrated.

  11. Acid sensing by sweet and bitter taste neurons in Drosophila melanogaster

    OpenAIRE

    Charlu, Sandhya; Wisotsky, Zev; Medina, Adriana; Dahanukar, Anupama

    2013-01-01

    Drosophila melanogaster can taste various compounds and separate them into few basic categories such as sweet, bitter and salt taste. Here we investigate mechanisms underlying acid detection in Drosophila and report that the fly displays strong taste aversion to common carboxylic acids. We find that acid tastants act by the activation of a subset of bitter neurons and inhibition of sweet neurons. Bitter neurons begin to respond at pH 5 and show an increase in spike frequency as the extracellu...

  12. [Separation of zoledronic acid and its related substances by ion-pair reversed-phase high performance liquid chromatography].

    Science.gov (United States)

    Zhang, Xiaoqing; Jiang, Ye; Xu, Zhiru

    2004-07-01

    A rapid and simple ion-pair reversed-phase high performance liquid chromatographic method (HPLC) has been established for the routine analysis of zoledronic acid and its related substances. The chromatographic conditions were optimized based on the satisfactory separation of zoledronic acid from imidazol-1-ylacetic acid, their retention times and peak shape. The excellent separation of zoledronic acid from its related substances, including the remaining imidazol-1-ylacetic acid used in the synthesis of zoledronic acid and other impurities of oxidation and decomposition, was achieved within 9 min on a Hypersil C8 column with UV detection at 220 nm. The mobile phase was a mixture of methanol (20%) and 5 mmo/L phosphate buffer (80%) that contains 6 mmol/L tetrabutylammonium bromide. The resolution factor of zoledronic acid from its adjacent peak was more than 2.5. This is a simple and rapid method for the routine assay of zoledronic acid.

  13. 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...

  14. A unique "turn-on" fluorescence signalling strategy for highly specific detection of ascorbic acid using carbon dots as sensing probe.

    Science.gov (United States)

    Fong, Jessica Fung Yee; Chin, Suk Fun; Ng, Sing Muk

    2016-11-15

    Carbon dots (CDs) that showed strong blue fluorescence were successfully synthesised from sodium alginate via furnace pyrolysis. The single step pyrolytic synthesis was simple to perform while yielded CDs with high photostability, good water solubility and minimum by-products. In order to design the probe with "turn-on" sensing capability, the CDs were screened against a series of metal cations to first "turn-off" the fluorescence. It was found that ferric ions (Fe(3+)) were most responsive and effective in quenching the fluorescence of CDs. Based on this observation, the conditioning of the probe was performed to ensure the fluorescence was completely quenched, while not overloading the system with Fe(3+). At the optimised condition, the CDs-Fe(3+) mixture served as a highly specific detection probe for ascorbic acid (AA). The analytical potential of the probe was evaluated and showed a good linear range of response for AA concentration of 24-40μg/mL. The selectivity study against other possible co-existing species was carried out and proved that our unique "turn-on" fluorescence signalling strategy was highly effective and selective towards AA as the target analyte. The probe was demonstrated for quantification of AA in real samples, which was the commercially available vitamin C supplement. The result showed good accuracy with minimum deviation from standard method adopted for validation purpose. PMID:27290666

  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

    degradation in terms of weight loss and molecular weight decrease. The presence of phosphoric acid as an inevitable dopant of the membranes, on the other hand, significantly impeded the membrane degradation by means of metal ion complexing, decreased pH, and acid–base interactions with the amino groups....... 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...... 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....

  16. Elution of nickel ions from alginate beads in an acid media; Elucion de iones de niquel desde esferas de alginato en un medio acido

    Energy Technology Data Exchange (ETDEWEB)

    Aracena, A.; Carcamo, F.; Jerez, O.; Constanzo, R.

    2016-05-01

    Elution of nickel ions from alginate beads was studied in a temperature range of 2 to 80 degree centigrade and a sulfuric acid concentration between 0.005 to 2.5 g L{sup -}1. The elution mechanism was established by ion exchange between nickel and ions protons, obtaining a value of 93% elution at a temperature of 80 degree centigrade and a H{sub 2}SO{sub 4} concentration of 0.25 g L{sup -}1. The influence of other acids on nickel elution was also studied. The nickel elution rate was significantly influenced by temperature and concentration of H{sub 2}SO{sub 4}. Elution kinetics of nickel ions was studied, and the 1-(1-α){sup 1}/3=k{sub a}ppt model properly described the kinetics of this reaction. The dependence of nickel elution on the sulfuric acid concentration was of the order of 0.33. Moreover, the intrinsic rate constants were determined and an activation energy value of 54.5 kJ mol{sup -}1 was obtained for the temperature range studied. The results indicated that the nickel elution is a process controlled by chemical reactions. (Author)

  17. Simultaneous determination of three chloroacetic acids, three herbicides, and 12 anions in water by ion chromatography.

    Science.gov (United States)

    Luo, Ximing; Chen, Liang; Zhao, Yanqing

    2015-09-01

    An ion chromatography method was developed for the simultaneous detection of three soluble herbicides (glyphosate, bentazone and picloram), three chlorine disinfection byproducts (monochloroacetic acid, dichloroacetic acid and trichloroacetic acid) and 12 anions in water (Cl(-), Br(-), SO4(2-), CO3(2-), ClO3(-), ClO4(-), BrO3(-), PO4(3-), NO2(-), NO3(-), CH3COO(-) and COO(-)). High linearity (r(2) > 0.996) was observed for all target analytes for each respective concentration range. The limit of detection and limit of quantitation were between 0.21-0.85 and 0.06-25.46 μg/L, respectively. However, the interference effect of Cl(-), NO3(-) , SO4 (2-) and CO3(2-) on some target analytes must be considered during the analysis. Sample pre-treatment by a hydrogen column (H-column) required to reduce the negative effect of CO3(2-). Additionally, sample pre-treatment by a sliver-hydrogen column (Ag-H-column) is required when Cl(-) > 100 mg/L and SO4(2-) 100 mg/L and SO4(2-) > 50 mg/L. When Cl(-) > 100 mg/L, SO4(2-) > 50 mg/L and CO3(2-) > 20 mg/L, the sample pre-treatment by either an Ag-H-Ba-column or an Ag-H-column and Ba-column is required to minimize interference.

  18. 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.)

  19. IN VITRO MASS-SCREENING OF LACTIC ACID BACTERIA AS POTENTIAL BIOSORBENTS OF CESIUM AND STRONTIUM IONS

    OpenAIRE

    Hideki Kinoshita; Yuka Sato1; Fumika Ohtake; Mitsuharu Ishida; Toshikazu Komoda; Haruki Kitazawa; Tadao Saito; Kazuhiko Kimura

    2015-01-01

    Many radionuclides were scattered by the explosion at the Fukushima Daiichi Nuclear Power Station. We examined whether lactic acid bacteria (LAB) can sorb cesium ions (Cs+) and strontium ions (Sr2+) for radioprotection. Many strains showed biosorption to Cs+ and Sr2+ using an in vitro mass-screening although each strain showed different sorption. We selected MYU 111, MYU 758, and MYU 759 strains that showed especially high biosorption to Cs+ and/or Sr2+. MYU 111 was identified as Lactobacillu...

  20. Preparation and characterization of 5-sulphosalicylic acid doped tetraethoxysilane composite ion-exchange material by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Suhail-ul; Islam, Nasarul; Ahad, Sozia; Fatima, Syed Zeeshan; Pandith, Altaf Hussain, E-mail: altafpandit23@gmail.com

    2013-09-15

    Highlights: • Sulphosalicylic acid doped tetraethoxysilane composite is prepared by sol–gel method. •Its X-ray diffraction studies suggest that it is crystalline in nature. • This material shows selectivity for Mg(II) and Ni(II) ions in aqueous solutions. • Separation of Ni(II) from binary mixtures was successfully achieved on this material. -- Abstract: In this manuscript, we report the preparation and characterization of sulphosalicylic doped tetraethoxysilane (SATEOS), composite material by sol–gel method as a new ion exchanger for the removal of Ni(II) from aqueous solution. The fine granular material was prepared by acid catalyzed condensation polymerization through sol–gel mechanism in the presence of cationic surfactant. The material has an ion exchange capacity of 0.64 mequiv./g(dry) for sodium ions, 0.60 mequiv./g(dry) for potassium ions, 1.84 mequiv./g(dry) for magnesium ions, 1.08 mequiv./g(dry) for calcium ions and 1.36 mequiv./g(dry) for strontium ions. Its X-ray diffraction studies suggest that it is crystalline in nature. The material has been characterized by SEM, IR, TGA and DTG so as to identify the various functional groups and ion exchange sites present in this material. Quantum chemical computations at DFT/B3LYP/6-311G (d,p) level on model systems were performed to substantiate the structural conclusions based ion instrumental techniques. Investigations into the elution behaviour, ion exchange reversibility and distribution capacities of this material towards certain environmentally hazardous metal ions are also performed. The material shows good chemical stability towards acidic conditions and exhibits fast elution of exchangeable H{sup +} ions under neutral conditions. This material shows remarkable selectivity for Ni(II) and on the basis of its K{sub d} value (4 × 10{sup 2} in 0.01 M HClO{sub 4}) some binary separations of Ni(II) from other metal ions are performed.

  1. Molecular basis for amino acid sensing by family C G-protein-coupled receptors

    DEFF Research Database (Denmark)

    Wellendorph, Petrine; Bräuner-Osborne, Hans

    2009-01-01

    -alpha;-amino acid receptor G-protein-coupled receptor family C, group 6, subtype A (GPRC6A) and seven orphan receptors. Aside from the orphan receptors, the family C GPCRs are dimeric receptors characterized by a large extracellular Venus flytrap domain which bind the endogenous agonists. Except from the GABA(B1......-2) and T1R2-3 receptor, all receptors are either activated or positively modulated by amino acids. In this review, we outline mutational, biophysical and structural studies which have elucidated the interaction of the amino acids with the Venus flytrap domains, molecular mechanisms of receptor selectivity...

  2. Novel redox-sensing modules : Accessory protein- and nucleic acid-mediated signaling

    NARCIS (Netherlands)

    Siedenburg, Gabriele; Groves, Matthew R; Ortiz de Orué Lucana, Darío

    2012-01-01

    SIGNIFICANCE: Organisms have evolved both enzymatic and nonenzymatic pathways to prevent oxidative damage to essential macromolecules, including proteins and nucleic acids. Pathways modulated by different protein-based sensory and regulatory modules ensure a rapid and appropriate response. RECENT AD

  3. Genetic Evolution of a Helicobacter pylori Acid-Sensing Histidine Kinase and Gastric Disease.

    Science.gov (United States)

    Krishna, Uma; Romero-Gallo, Judith; Suarez, Giovanni; Azah, Ayeetin; Krezel, Andrzej M; Varga, Matthew G; Forsyth, Mark H; Peek, Richard M

    2016-08-15

    Helicobacter pylori is the strongest risk factor for gastric adenocarcinoma, which develops within a hypochlorhydric environment. We sequentially isolated H. pylori (strain J99) from a patient who developed corpus-predominant gastritis and hypochlorhydia over a 6-year interval. Archival J99 survived significantly better under acidic conditions than recent J99 strains. H. pylori arsRS encodes a 2-component system critical for stress responses; recent J99 isolates harbored 2 nonsynonymous arsS mutations, and arsS inactivation abolished acid survival. In vivo, acid-resistant archival, but not recent J99, successfully colonized high-acid-secreting rodents. Thus, genetic evolution of arsS may influence progression to hypochlorhydia and gastric cancer. PMID:27190191

  4. Separation and Detection of Lanthanide Ions with Nitrilotri (methylenephosphonic) Acid as Complexing Agent and Eluent by IPC

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A mixture containing eleven lanthanide ions was separated and detected on an anion-exchange co-lumn by ion chromatography with indirect photometry detection (IPC).An aqueous solution of 1.5×10-2mol/L nitrilotri(methylenephosphonic) acid and 2.5×10-3mol/L tiron was used as the eluent in which the former served as complexing agent and eluent,the latter played as color reagent and eluent.The effects of acidity,concentration and composition of eluent on the retention behavior of the analytes and detection sensitivity are discussed.

  5. The Kinetic Aspects of the Interaction of Nitrite Ions with Sulfanilic Acid and 1-Naphthylamine in Aqueous and Micellar Media

    Science.gov (United States)

    Korneeva, O. I.; Chernova, R. K.; Doronin, S. Yu.

    2008-04-01

    The kinetics of the reaction of nitrite ions with sulfanilic acid and 1-naphthylamine in aqueous and micellar (sodium dodecyl sulfate) media was studied step-by-step. The diazotization of sulfanilic acid with the nitrite ion was found to occur virtually instantaneously. Anionic surfactant micelles did not influence the rate of this reaction. The calculated effective rate constants and activation energies of the azo coupling reaction between synthesized sulfophenyldiazonium and 1-naphthylamine showed that the passage from water into the micellar medium decelerated the reaction. It was found that sodium dodecyl sulfate micelles played the role of a reagent separator.

  6. Synthesis and Characteristic Study on Complexes of Europium(Ⅲ) and Maleic Acid Doped with Non-Fluorescent Ions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Complex of europium (Ⅲ) with maleic acid, and binuclear complexes of europium(Ⅲ)with maleic acid doped with non-fluorescent ions gadolinium, lanthanum and yttrium, were synthesized. The compositions and structures of complexes were characterized with elemental analysis, single crystal X-ray diffraction, IR and DSC-TG. Fluorescent properties were studied with fluorescence spectrum. The results indicated that the strongest fluorescent complexes were obtained when the ratio of europium and non-fluorescent ion was 8: 2. The order of Eu3+ fluorescence strengthened by three doped rare earths was Gd3+>La3+>Y3+.

  7. Acidic Tumor Microenvironment and pH-Sensing G protein-Coupled Receptors

    OpenAIRE

    Justus, Calvin R.; Lixue eDong; Yang, Li V.

    2013-01-01

    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 mechani...

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

    OpenAIRE

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

    2013-01-01

    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 mechan...

  9. 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.

  10. Equilibrium processes in the system of vanadyl (2) ion -hydrazide of isonicotinic acid

    International Nuclear Information System (INIS)

    Method of proton magnetic relaxation was used to study the system of vanadyl (2) ion - hydrazide of isonicotinic acid in -1-4 pH range. It is shown that formation of VOH2HL4+ (1) and VOHHL3+ (2) complex forms takes place in the region of pH values of -0.5-0.3 and 0.3-1.5 repspectively. Values of equilibrium constants of 1 and 2 complex formation lgK1 and lgK2, equal to 1.5±0.1 and -0.7±0.1 respectively, were calculated. Deprotonation of complex 2 with formation of difficultly soluble compounds, containing, probably, two molecules of deprotonated ligand, takes place at pH>2.5. The calculated constant of deprotonation is equal to 1.1±0.1

  11. A study on structural changes of amino acids implanted with low energy ions by FTIR spectroscopy

    International Nuclear Information System (INIS)

    The structural changes of aspartic acid (Asp) and phenylalanine (Phe) implanted with N+ ions of 30 keV were studied using Fourier transform infrared (FTIR) spectroscopy. Implanted at the same fluence of 1 x 1016/cm2, similar phenomena were observed in both Asp and Phe, i.e., the relative intensities of NH3+ vibration decreased and those of COO- stretching vibration increased. The changes of absorption intensities in Phe were more obvious than those in Asp. It was also observed that the intensities of COOH, COO- and NH3+ groups of Asp changed regularly with increasing implantation fluences. The possible reasons responsible for these results were studied. The radiolysis products of Asp implanted at a higher fluence of 6 x 1016/cm2 were analyzed

  12. Photochemical oxidation of chloride ion by ozone in acid aqueous solution.

    Science.gov (United States)

    Levanov, Alexander V; Isaykina, Oksana Ya; Amirova, Nazrin K; Antipenko, Ewald E; Lunin, Valerii V

    2015-11-01

    The experimental investigation of chloride ion oxidation under the action of ozone and ultraviolet radiation with wavelength 254 nm in the bulk of acid aqueous solution at pH 0-2 has been performed. Processes of chloride oxidation in these conditions are the same as the chemical reactions in the system O3 - OH - Cl(-)(aq). Despite its importance in the environment and for ozone-based water treatment, this reaction system has not been previously investigated in the bulk solution. The end products are chlorate ion ClO3(-) and molecular chlorine Cl2. The ions of trivalent iron have been shown to be catalysts of Cl(-) oxidation. The dependencies of the products formation rates on the concentrations of O3 and H(+) have been studied. The chemical mechanism of Cl(-) oxidation and Cl2 emission and ClO3(-) formation has been proposed. According to the mechanism, the dominant primary process of chloride oxidation represents the complex interaction with hydroxyl radical OH with the formation of Cl2(-) anion-radical intermediate. OH radical is generated on ozone photolysis in aqueous solution. The key subsequent processes are the reactions Cl2(-) + O3 → ClO + O2 + Cl(-) and ClO + H2O2 → HOCl + HO2. Until the present time, they have not been taken into consideration on mechanistic description and modelling of Cl(-) oxidation. The final products are formed via the reactions 2ClO → Cl2O2, Cl2O2 + H2O → 2H(+) + Cl(-) + ClO3(-) and HOCl + H(+) + Cl(-) ⇄ H2O + Cl2. Some portion of chloride is oxidized directly by O3 molecule with the formation of molecular chlorine in the end.

  13. SYNTHESIS OF MACROPOROUS HUMIC ACID RESINS AND THEIR CHELATING PROPERTIES FOR HEAVY METAL IONS

    Institute of Scientific and Technical Information of China (English)

    CHEN Yiyong; MAO Xueqin; ZHU Dongwei; ZHENG Ping

    1984-01-01

    Macroporous HA resins (HAR) can be prepared in pearl form by grafting HA onto crosslinkec PS through azo or through ester and / or ether linkages. At pH 13 and the HA / PSNH2 weight ratio 0.7-1.0, PSN2+Cl-couples with HA and results in the formation of azo-type HA resin (HAR-A), which shows good adsorbility towards heavy metal ions. The Cu2+ sorption capacity of ester / ether type humic acid resin (HAR-E) is increased by lengthening the reaction time of HA and PSCH2Cl. The structure of HAR is discussed on the basis of the IR spectra. The sorption capacity of HAR-A is 1.01 mmol / g for Cd2+and 0.6-0.53 mmol/g for Ni2+,Mn2+,Cu2+,Co3+ and Zn2+, respectively. The calculated distribution coefficients of heavy metal ions on HAR-A can be arranged in the following order: CuV+(8.7 × 103)>Cd2+(3.8 × 102)>Zn2+(2.4 × 102)>Ni2+(1. 8 × 102)>Mn2+(4.9 × 10). At pH 6.5, Cu2+, Cd2+, Ni2+, Mn2+ can be quantitatively adsorbed by HAR-A and completely eluted with 1N HNO3. HAR-A can be regenerated and reused Trace quantities of the above-mentioned heavy metal ions in four samples of the natural occurring water and one sample of the tap water were analyzed by using HAR-A.

  14. Modular calibrant sets for the structural analysis of nucleic acids by ion mobility spectrometry mass spectrometry.

    Science.gov (United States)

    Lippens, Jennifer L; Ranganathan, Srivathsan V; D'Esposito, Rebecca J; Fabris, Daniele

    2016-06-20

    This study explored the use of modular nucleic acid (NA) standards to generate calibration curves capable of translating primary ion mobility readouts into corresponding collision cross section (CCS) data. Putative calibrants consisted of single- (ss) and double-stranded (ds) oligo-deoxynucleotides reaching up to ∼40 kDa in size (i.e., 64 bp) and ∼5700 Å(2) in CCS. To ensure self-consistency among reference CCS values, computational data obtained in house were preferred to any experimental or computational data from disparate sources. Such values were obtained by molecular dynamics (MD) simulations and either the exact hard sphere scattering (EHSS) or the projection superposition approximation (PSA) methods, and then plotted against the corresponding experimental values to generate separate calibration curves. Their performance was evaluated on the basis of their correlation coefficients and ability to provide values that matched the CCS of selected test samples mimicking typical unknowns. The results indicated that the predictive power benefited from the exclusion of higher charged species that were more susceptible to the destabilizing effects of Coulombic repulsion. The results revealed discrepancies between EHSS and PSA data that were ascribable to the different approximations used to describe the ion mobility process. Within the boundaries defined by these approximations and the challenges of modeling NA structure in a solvent-free environment, the calibrant sets enabled the experimental determination of CCS with excellent reproducibility (precision) and error (accuracy), which will support the analysis of progressively larger NA samples of biological significance. PMID:27152369

  15. Salinity and Salicylic Acid Interactions in Affecting Nitrogen Assimilation, Enzyme Activity, Ions Content and Translocation Rate of Maize Plants

    International Nuclear Information System (INIS)

    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 (NO3) 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

  16. Incorporation of Zn(2+) ions into BaTiO3:Er(3+)/Yb(3+) nanophosphor: an effective way to enhance upconversion, defect luminescence and temperature sensing.

    Science.gov (United States)

    Mahata, Manoj Kumar; Koppe, Tristan; Mondal, Tanusree; Brüsewitz, Christoph; Kumar, Kaushal; Kumar Rai, Vineet; Hofsäss, Hans; Vetter, Ulrich

    2015-08-28

    Ferroelectric BaTiO3 became a multifunctional material via doping of lanthanide ions (0.3 mol% Er(3+)/3.0 mol% Yb(3+)) and subsequently upconversion luminescence was enhanced by incorporation of Zn(2+) ions. Upconversion luminescence of BaTiO3:Er(3+)/Yb(3+) perovskite nanophosphor has been studied using 800 and 980 nm laser excitations. The emission dynamics is studied with respect to its dependence on input power and external temperature including lifetime. Based on time-resolved spectroscopy, it is inferred that two types of Er(3+) sites are present in the barium titanate lattice. The first one is a short lived component (minor species) present at 6-coordinated Ti-sites of low symmetry while the second one is a long lived component (major species), present at 12-coordinated Ba-sites with high symmetry. The influence of the introduction of Zn(2+) ions on the lifetime of (4)S3/2 and (4)F9/2 levels of Er(3+) ions is also investigated. Enhanced temperature sensing performance (120 K to 505 K) of the material is observed using the fluorescence intensity ratio technique, employing the emission from the thermally coupled, (2)H11/2 and (4)S3/2 energy levels of Er(3+) ions. The defect luminescence of the material is also found to increase upon Zn-doping. PMID:26206553

  17. 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%. PMID:24439499

  18. Dual Enzyme-Responsive Capsules of Hyaluronic Acid-block-Poly(Lactic Acid) for Sensing Bacterial Enzymes.

    Science.gov (United States)

    Tücking, Katrin-Stephanie; Grützner, Verena; Unger, Ronald E; Schönherr, Holger

    2015-07-01

    The synthesis of novel amphiphilic hyaluronic acid (HYA) and poly(lactic acid) (PLA) block copolymers is reported as the key element of a strategy to detect the presence of pathogenic bacterial enzymes. In addition to the formation of defined HYA-block-PLA assemblies, the encapsulation of fluorescent reporter dyes and the selective enzymatic degradation of the capsules by hyaluronidase and proteinase K are studied. The synthesis of the dual enzyme-responsive HYA-b-PLA is carried out by copper-catalyzed Huisgen 1,3-dipolar cycloaddition. The resulting copolymers are assembled in water to form vesicular structures, which are characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering (DLS), and fluorescence lifetime imaging microscopy (FLIM). DLS measurements show that both enzymes cause a rapid decrease in the hydrodynamic diameter of the nanocapsules. Fluorescence spectroscopy data confirm the liberation of encapsulated dye, which indicates the disintegration of the capsules and validates the concept of enzymatically triggered payload release. Finally, cytotoxicity assays confirm that the HYA-b-PLA nanocapsules are biocompatible with primary human dermal microvascular endothelial cells. PMID:25940300

  19. 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.

  20. Concentration of zinc ions in perchlorate medium by a menbrane-gel using an acid extractant (DEHPA)

    OpenAIRE

    Belhadji L.; Belkacemi F.; Hadj-Boussaad D.E.

    2013-01-01

    Recent decades, it is an awareness of the importance of ecological balance in the environment, balances threatened by industrial pollution. A new spirit presides we seek to minimize pollution of receiving waters. The present work is to study the liquid-gel-extraction of zinc ions in perchlorate medium by an acid extractant: the di (ethyl-2 hexyl) phosphorique acid, or DEHPA. Two types of polymers were used as supports of solvent extraction: a polybutadiene rubber cross-linked respectively wit...

  1. 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.

  2. Studies of endothelial monolayer formation on irradiated poly-L-lactide acid with ions of different stopping power and velocity

    Science.gov (United States)

    Arbeitman, Claudia R.; del Grosso, Mariela F.; Ibañez, Irene L.; Behar, Moni; Grasselli, Mariano; Bermúdez, Gerardo García

    2015-12-01

    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 cm2 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.

  3. 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.

  4. Integrated li-ion ultracapacitor with lead acid battery for vehicular start-stop

    Science.gov (United States)

    Manla, Emad

    Advancements in automobile manufacturing aim at improving the driving experience at every level possible. One improvement aspect is increasing gas efficiency via hybridization, which can be achieved by introducing a feature called start-stop. This feature automatically switches the internal combustion engine off when it idles and switches it back on when it is time to resume driving. This application has been proven to reduce the amount of gas consumption and emission of greenhouse effect gases in the atmosphere. However, the repeated cranking of the engine puts a large amount of stress on the lead acid battery required to perform the cranking, which effectively reduces its life span. This dissertation presents a hybrid energy storage system assembled from a lead acid battery and an ultracapacitor module connected in parallel. The Li-ion ultracapacitor was tested and modeled to predict its behavior when connected in a system requiring pulsed power such as the one proposed. Both test and simulation results show that the proposed hybrid design significantly reduces the cranking loading and stress on the battery. The ultracapacitor module can take the majority of the cranking current, effectively reducing the stress on the battery. The amount of cranking current provided by the ultracapacitor can be easily controlled via controlling the resistance of the cable connected directly between the ultracapacitor module and the car circuitry.

  5. A new chelating ion-exchanger containing p-bromophenylhydroxamic acid as functional group

    International Nuclear Information System (INIS)

    A new chelating resin based on macroreticular acrylonitrile-divinylbenzene copolymer and containing hydroxamic acid functional groups has been synthesized. It is highly-stable in acidic and alkaline solutions. The sorption characteristics of Cu(II), Cd(II), Pb(II), Zn(II), U(VI), Cr(VI), V(V), Co(II), Ni(II), Ca(II) and Mg(II) have been investigated over the pH range 1.0-6.0. The effect of various electrolytes at different ionic strengths on the Ksub(d) values for Cu(II), Cd(II), Pb(II) and Zn(II) has been studied systematically. Chromatographic separations of copper(II) and nickel(II) from cobalt(II), and of uranium(VI) from chromium(VI) by selective sorption at controlled pH, have been developed. The ion-exchanger can be used for purification of inorganic salts, and analysis of brass and bauxite. (author)

  6. Utilization of a spiropyran derivative in a polymeric film optode for selective fluorescent sensing of zinc ion

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Ying; SHAO; Na; YANG; Ronghua; LI; Ke'an; LIU; Feng; CHAN; Winghong; MO; Tian

    2006-01-01

    A new spiropyran derivative was synthesized and first utilized in a polymeric film-based optical sensor for zinc ion. Spiropyrans, combining the characteristics of metal binding and signal transduction, show potential function in the design of optical chemical sensors (optodes) toward metal ions. When embedded in a plasticized poly (vinyl chloride) (PVC) membrane, the newly synthesized spiropyran derivative 1 exhibits obvious fluorescence enhancement at 630 nm in the presence of zinc ion in aqueous solution. With the optimum condition described, the optode membrane responds to also exhibits high selectivity toward zinc ion over transition metal ions including Hg2+, Cd2+, Pb2+, Cu2+,Fe3+and common cationic ions presented in the physiological fluids.

  7. Regulation of the synthesis of barley aleurone. cap alpha. -amylase by gibberellic acid and calcium ions

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R.L.; Carbonell, J.

    1984-09-01

    The effects of gibberellic acid (GA/sub 3/) and calcium ions on the production of ..cap alpha..-amylase and acid phosphatase by isolated aleurone layers of barley (Hordeum vulgare L. cv Himalaya) were studied. Aleurone layers not previously exposed to GA/sub 3/ or CA/sup 2 +/ show qualitative and quantitative changes in hydrolase production following incubation in either GA/sub 3/ or CA/sup 2 +/ or both. In cubation in H/sub 2/O or CA/sup 2 +/ results in the production of low levels of ..cap alpha..-amylase or acid phosphatase. The addition of GA/sub 3/ to the incubation medium causes 10- to 20-fold increase in the amounts of these enzymes released from the tissue, and addition of CA/sup 2 +/ at 10 millimolar causes a further 8- to 9-fold increase in ..cap alpha..-amylase release and a 75% increase in phosphatase release. Production of ..cap alpha..-amylase isoenzymes is also modified by the levels of GA/sub 3/ and CA/sup 2 +/ in the incubation medium. ..cap alpha..-amylase 2 is produced under all conditions of incubation, while ..cap alpha..-amylase 1 appears only when layers are incubated in GA/sub 3/ or GA/sub 3/ plus CA/sup 2 +/. The synthesis of ..cap alpha..-amylases 3 and 4 requires the presence of both GA/sub 3/ and CA/sup 2 +/ in the incubation medium. Laurell rocket immunoelectrophoresis shows that two distinct groups of ..cap alpha..-amylase antigens are present in incubation media of aleurone layers incubated with both GA/sub 3/ and CA/sup 2 +/, while only one group of antigens is found in media of layers incubated in GA/sub 3/ alone. Strontium ions can be substituted for CA/sup 2 +/ in increasing hydrolase production, although higher concentrations of Sr/sup 2 +/ are requried for maximal response. We conclude that GA/sub 3/ is required for the production of ..cap alpha..-amylase 1 and that both GA/sub 3/ and either CA/sup 2 +/ or Sr/sup 2 +/ are required for the production of isoenzymes 3 and 4 of barley aleurone ..cap alpha..-amylase. 22 references, 8

  8. [Determination of succinic acid in desvenlafaxine succinate by high performance ion-exclusion chromatography and high performance ion-exchange chromatography].

    Science.gov (United States)

    Zong, Yanping; Li, Jinghua; Sun, Wei; Liu, Guixia; Lu, Jinghua; Shan, Guangzhi

    2016-02-01

    New methods were developed for the determination of succinic acid in desvenlafaxine succinate (DVS) by high performance ion-exclusion chromatography (HPIEC) and high performance ion-exchange chromatography (HPIC). HPIEC and HPIC methods were used separately to determinate the succinic acid in DVS. With HPIEC, the sample was diluted with 2. 50 x 10(-3) mol/L sulfuric acid solution and filtrated by 0. 22 µm polyether sulfone filter membrane, and then analyzed by HPIEC directly without any further pretreatment. The analytical column was Phenomenex Rezex ROA-organic Acid H+(8%) (300 mmx7. 8 mm). The mobile phase was 2. 50x10(-3) mol/L sulfuric acid solution at the flow rate of 0. 5 mL/min. The column temperature was set at 40 °C, and the detection wavelength was 210 nm. The injection volume was 10 KL. The assay was quantified by external standard method. With HPIC, the sample was diluted with ultrapure water and filtrated by 0. 22 µm polyether sulfone filter membrane, and then analyzed by HPIC directly without any further pretreatment. The analytical column was Dionex IonPac AS11-HC (250 mm x 4 mm) with a guard column IonPacAG11-HC (50 mm x 4 mm). Isocratic KOH elute generator was used at the flow rate of 1. 0 mL/min. The detection was performed by a Dionex suppressed (DIONEX AERS 500 4-mm) conductivity detector. The injection volume was 10 µL. The content computation was performed with peak area external reference method. The results of HPIEC method for succinic acid were 28. 8%, 28. 9% and 28. 9%, while the results of HPIEC method were 28. 2%, 28. 6% and 28. 6%. The results of HPIEC and HPIC methods were not significantly different. The two methods can both be used to determine the contents of succinic acid in DVS. The surveillance analytical method should be chosen according to the situation. PMID:27382725

  9. Application of Carbon-Microsphere-Modified Electrodes for Electrochemistry of Hemoglobin and Electrocatalytic Sensing of Trichloroacetic Acid

    Directory of Open Access Journals (Sweden)

    Wen-Cheng Wang

    2015-12-01

    Full Text Available 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.

  10. 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  

  11. Synergistic effect between cationic gemini surfactant and chloride ion for the corrosion inhibition of steel in sulphuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Lingguang [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China)], E-mail: lgqiu@ahu.edu.cn; Wu Yun; Wang Yimin; Jiang Xia [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China)

    2008-02-15

    Corrosion inhibition of cold rolled steel in 0.5 mol L{sup -1} sulphuric acid by a quaternary ammonium gemini surfactant, l,3-propane-bis(dimethyl dodecylammonium bromide) (designated as 12-3-12), in the absence and presence of chloride ions was investigated at different temperatures. The results revealed significant synergistic effect between gemini 12-3-12 and chloride ions for the corrosion protection of cold rolled steel in sulphuric acid, and that the novel composite inhibitor system containing cationic gemini surfactant and chloride ions was efficient and low-cost for steel corrosion inhibition in sulphuric acid medium, even when concentration of 12-3-12 was as low as 1 x 10{sup -6} mol L{sup -1}. By fitting the obtained experimental data with Langmuir adsorption model and Arrhenius equation, some thermodynamic and kinetic parameters such as adsorption free energy, the apparent activation energy, and the pre-exponential factor were estimated. The adsorption mechanism of the gemini surfactant onto steel surface in acid medium in the absence and presence of chloride ions was also discussed, respectively.

  12. Chemical Speciation Analysis of Sports Drinks by Acid-Base Titrimetry and Ion Chromatography: A Challenging Beverage Formulation Project

    Science.gov (United States)

    Drossman, Howard

    2007-01-01

    Students have standardized a sodium hydroxide solution and analyzed commercially available sports drinks by titrimetric analysis of the triprotic citric acid, dihydrogen phosphate, and dihydrogen citrate and by ion chromatography for chloride, total phosphate and citrate. These experiments are interesting examples of analyzing real-world food and…

  13. Breeding of high yield strain producing acid-stable α-amylase by N+ ion beam irradiation

    International Nuclear Information System (INIS)

    Bacillus subtilis BF7658, which produces medium-temperature α-amylase,was implanted with N+ ion beam to breed mutants. Under the optimal fluence of 1 x 1016 cm-2, a mutant TCCC 11525 producing the acid-stable and medium-temperature α-amylase was obtained. The activity of the mutagenised enzyme is 207 U/mL. (authors)

  14. 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 h

  15. Quantitative Phosphoproteome Analysis of Lysophosphatidic Acid Induced Chemotaxis applying Dual-step ¹⁸O Labeling Coupled with Immobilized Metal-ion Affinity Chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Shi-Jian; Wang, Yingchun; Jacobs, Jon M.; Qian, Weijun; Yang, Feng; Tolmachev, Aleksey V.; Du, Xiuxia; Wang, Wei; Moore, Ronald J.; Monroe, Matthew E.; Purvine, Samuel O.; Waters, Katrina M.; Heibeck, Tyler H.; Adkins, Joshua N.; Camp, David G.; Klemke, Richard L.; Smith, Richard D.

    2008-10-01

    Reversible protein phosphorylation is a central cellular regulatory mechanism in modulating protein activity and propagating signals within cellular pathways and networks. Development of more effective methods for the simultaneous identification of phosphorylation sites and quantification of temporal changes in protein phosphorylation could provide important insights into molecular signaling mechanisms in a variety of different cellular processes. Here we present an integrated quantitative phosphoproteomics approach and its applications for comparative analysis of Cos-7 cells in response to lysophosphatidic acid (LPA) gradient stimulation. The approach combines trypsin-catalyzed 16O/18O labeling plus 16O/18O-methanol esterification labeling for quantitation, a macro- Immobilized Metal-ion Affinity Chromatography trap for phosphopeptide enrichment, and a monolithic capillary column with integrated electrospray emitter. LC separation and MS/MS is followed by neutral loss-dependent MS/MS/MS for phosphopeptide identification using a linear ion trap (LTQ)-FT mass spectrometer and complementary searching algorithms for interpreting MS/MS spectra. Protein phosphorylation involved in various signaling pathways of cell migration were identified and quantified, such as mitogen-activated protein kinase 1, dual-specificity mitogen-activated protein kinase kinase 2, and dual-specificity tyrosine-phosphorylation regulated kinase 1b, and a number of Rho GTPase-activating proteins. These results demonstrate the efficiency of this quantitative phosphoproteomics approach and its application for rapid discovery of phosphorylation events associated with gradient sensing and cell chemotaxis.

  16. Development of optical sensing system for detection of Fe ions using conductive polymer actuator based microfluidic pump

    OpenAIRE

    Kim, Jung Ho; Lau, King-Tong; Fay, Cormac; Diamond, Dermot

    2008-01-01

    In this paper, we present a novel microfluidic optical sensing system by combining a low-power conductive polymer -based microfluidic pump and a microfluidic chip integrated with an optical sensor. A self priming microfluidic pump is developed using a polypyrrole. A microfluidic chip- optical detector module that contained an optical cuvette with LED and photo-diode optical sensing module was fabricated. Integration of the micro pump and the microfluidic chips complete...

  17. 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.

  18. THERMODYNAMICS ADSORPTION OF MANGANESE ION ON 1-(2-PYRIDYLAZO)-2-NAPHTHOL-6-SULPHONIC ACID IMPREGNATED RESIN

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An ion-exchange resin of type 201×7 was impregnated with the reagent 1-(2-Pyridylazo)-2-naphthol-6-sulphonic Acid (PAN-S). The adsorption characteristics of PAN-S resin for manganese ion were studied on the static equilibrium adsorption. Within temperature range of 288K~313K and the concentration range investigated, equilibrium data for the adsorption of manganese ions from aqueous solutions by PAN-S resin were obtained and correlated with Freundlich and Langmuir equation. The results showed that the process of the adsorption of manganese ions from aqueous solution by PAN-S was an exothermic process. Estimations of the isothermic enthalpy change of adsorption,free energy change and entropy of adsorption are reported,and the adsorption behaviors are reasonably interpreted.

  19. Nucleic Acid Aptamers: An Emerging Tool for Biotechnology and Biomedical Sensing

    Directory of Open Access Journals (Sweden)

    Ti-Hsuan Ku

    2015-07-01

    Full Text Available Detection of small molecules or proteins of living cells provides an exceptional opportunity to study genetic variations and functions, cellular behaviors, and various diseases including cancer and microbial infections. Our aim in this review is to give an overview of selected research activities related to nucleic acid-based aptamer techniques that have been reported in the past two decades. Limitations of aptamers and possible approaches to overcome these limitations are also discussed.

  20. Strong Fluorescent Smart Organogel as a Dual Sensing Material for Volatile Acid and Organic Amine Vapors.

    Science.gov (United States)

    Xue, Pengchong; Yao, Boqi; Wang, Panpan; Gong, Peng; Zhang, Zhenqi; Lu, Ran

    2015-11-23

    An L-phenylalanine derivative (C12PhBPCP) consisting of a strong emission fluorophore with benzoxazole and cyano groups is designed and synthesized to realize dual responses to volatile acid and organic amine vapors. The photophysical properties and self-assembly of the said derivative in the gel phase are also studied. C12PhBPCP can gelate organic solvents and self-assemble into 1 D nanofibers in the gels. UV/Vis absorption spectral results show H-aggregate formation during gelation, which indicates strong exciton coupling between fluorophores. Both wet gel and xerogel emit strong green fluorescence because the cyano group suppresses fluorescence quenching in the self-assemblies. Moreover, the xerogel film with strong green fluorescence can be used as a dual chemosensor for quantitative detection of volatile acid and organic amine vapors with fast response times and low detection limits owing to its large surface area and amplified fluorescence quenching. The detection limits are 796 ppt and 25 ppb for gaseous aniline and trifluoroacetic acid (TFA), respectively.

  1. [Simultaneous determination of 16 organic acids in feed additives by on-line enrichment and ion chromatography-mass spectrometry].

    Science.gov (United States)

    Xiong, Zhiyu; Dong, Ying; Zhou, Hongbin; Yu, Yang; Li, Jing; Sun, Li

    2014-02-01

    A novel analytical method for simultaneous determination of sixteen organic acids by on-line enrichment and ion chromatography-mass spectrometry (IC-MS) was developed. Online enrichment and separation of the organic acids were performed by ion chromatography on a homemade enrichment column and a homemade separation column. The qualitative and quantitative analyses of the organic acids were performed by mass spectrometry in selected ion monitoring (SIM) mode on the basis of atmospheric pressure chemical ionization (APCI) source in negative mode. The sample of 200 microL was injected for the analysis, and the on-line enrichment time was 3 min. The sodium hydroxide solution was used as a gradient elution system. The two columns made it possible to have a low limit of detection due to the good enrichment and separation capability. The sixteen organic acids were separated completely within 30 min. All curves showed good linearity within the test concentration ranges. The limits of detection (LODs) were between 0.01 and 0.22 mg/L, and the average recoveries were between 70.6% and 110.8%. The relative standard deviations (RSDs) were less than 6.3%. The results indicate that this method is simple, rapid, sensitive and accurate for the determination of the organic acids in feed additives.

  2. Perfluorosulfonic acid membrane catalysts for optical sensing of anhydrides in the gas phase.

    Science.gov (United States)

    Ayyadurai, Subasri M; Worrall, Adam D; Bernstein, Jonathan A; Angelopoulos, Anastasios P

    2010-07-15

    Continuous, on-site monitoring of personal exposure levels to occupational chemical hazards in ambient air is a long-standing analytical challenge. Such monitoring is required to institute appropriate health measures but is often limited by the time delays associated with batch air sampling and the need for off-site instrumental analyses. In this work, we report on the first attempt to use the catalytic properties of perfluorosulfonic acid (PSA) membranes to obtain a rapid, selective, and highly sensitive optical response to trimellitic anhydride (TMA) in the gas phase for portable sensor device application. TMA is used as starting material for various organic products and is recognized to be an extremely toxic agent by the National Institute for Occupational Safety and Health (NIOSH). Resorcinol dye is shown to become immobilized in PSA membranes and diffusionally constrain an orange brown product that results from acid-catalyzed reaction with more rapidly diffusing TMA molecules. FTIR, UV/vis, reaction selectivity to TMA versus trimellitic acid (TMLA), and homogeneous synthesis are used to infer 5,7- dihydroxyanthraquinone-2-carboxylic acid as the acylation product of the reaction. The color response has a sensitivity to at least 3 parts per billion (ppb) TMA exposure and, in addition to TMLA, excludes maleic anhydride (MA) and phthalic anhydride (PA). Solvent extraction at long times is used to determine that the resorcinol extinction coefficient in 1100 EW PSA membrane has a value of 1210 m(2)/g at 271.01 nm versus a value of 2010 m(2)/g at 275.22 nm in 50 vol% ethanol/water solution. The hypsochromic wavelength shift and reduced extinction coefficient suggest that the polar perfluorosulfonic acid groups in the membrane provide the thermodynamic driving force for diffusion and immobilization. At a resorcinol concentration of 0.376 g/L in the membrane, a partition coefficient of nearly unity is obtained between the membrane and solution concentrations and a

  3. Spectrophotometric determination and removal of unchelated europium ions from solutions containing Eu-diethylenetriaminepentaacetic acid chelate-peptide conjugates.

    Science.gov (United States)

    Elshan, N G R Dayan; Patek, Renata; Vagner, Josef; Mash, Eugene A

    2014-11-01

    Europium chelates conjugated with peptide ligands are routinely used as probes for conducting in vitro binding experiments. The presence of unchelated Eu ions in these formulations gives high background luminescence and can lead to poor results in binding assays. In our experience, the reported methods for purification of these probes do not achieve adequate removal of unchelated metal ions in a reliable manner. In this work, a xylenol orange-based assay for the quantification of unchelated metal ions was streamlined and used to determine levels of metal ion contamination as well as the success of metal ion removal on attempted purification. We compared the use of Empore chelating disks and Chelex 100 resin for the selective removal of unchelated Eu ions from several Eu-diethylenetriaminepentaacetic acid chelate-peptide conjugates. Both purification methods gave complete and selective removal of the contaminant metal ions. However, Empore chelating disks were found to give much higher recoveries of the probes under the conditions used. Related to the issue of probe recovery, we also describe a significantly more efficient method for the synthesis of one such probe using Rink amide AM resin in place of Tentagel S resin.

  4. Preparation of highly conjugated water-dispersible graphene-butyric acid for the enhancement of electron transfer within polyamic acid-benzoxazole: potential applications in electrochemical sensing.

    Science.gov (United States)

    Chen, Hsiao-Chien; Chen, Yen-Hsuan; Chen, Shi-Liang; Chern, Yaw-Terng; Tsai, Rung-Ywan; Hua, Mu-Yi

    2013-08-15

    To break through the long time and complex procedures for the preparation of highly conjugated reduced graphene oxide (r-GO) in developing electrochemical sensor, a time-saving and simple method is investigated in this study. One novel step of the exfoliated accompanying carboxylated graphene sheet from pristine is achieved via Friedel-Crafts acylation. By electrophilic aromatic substitution, the succinic anhydride ring is opened and attaches covalently to the graphene sheet (Gs) to form exfoliated graphene with grafted 1-one-butyric acid (Gs-BA). The grafting chain converts anions in aqueous solution to maintain Gs-BA in a stable dispersion and noticeably decreases the π-π stacking of the exfoliated Gs during the drying process. The analytical results of the absorption spectroscopy demonstrate that the conjugation of Gs-BA is not significantly destroyed by this chemical modification; Gs-BA retains the Gs electrical properties favorable for developing electrochemical sensors. When polyamic acid-benzoxazole (PAA-BO), a hydrogen peroxide (H₂O₂)-sensitive probe, hybridizes with Gs-BA to form Gs-BA-PAA-BO, the electron transfer rate relating to the response time improves markedly from 1.09 s(-1) to 38.8 s(-1). Additionally, it offers a high performance for H₂O₂ sensing in terms of sensitivity and response time, making this method applicable for developing glucose and choline biosensors.

  5. Two-Component Regulatory Systems – implication in the quorum sensing mechanisms and bacteriocin production in lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Lia–Mara Ditu

    2014-08-01

    Full Text Available For lactic acid bacteria, the mechanisms of quorum sensing and response are mediated by peptides or pheromones that interfere with the synthesis of antimicrobial peptides (AMP called bacteriocins, when these molecules reach a certain critical level of concentration. Generally, the synthesis and activity of pheromones is adjusted by means of a two-component regulatory system. The observation that some microorganisms, in particular lactic acid bacteria, produce bacteriocins according to the cell density, has led to the discovery of the involvement of QS mechanisms in the synthesis of these peptides. Bacteriocins synthesis is inducible, the process requiring the extracellular accumulation of peptides that functions as chemical messengers activators of bacteriocins synthesis. This minireview presents the molecular architecture and functions of two-component regulatory systems and ABC transporters implicated in the synthesis and secretion of nisin, one of the most studied bacteriocin. The elucidation of the intimate mechanisms of bacteriocins synthesis is equally of biotechnological and medical importance, opening interesting perspectives for the development of improved technologies for the production of bacteriocins with good yields, and also, for increasing the beneficial anti-infective roles of probiotic bacteria when administered in vivo.

  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. Separation of clavulanic acid from fermented broth of amino acids by an aqueous two-phase system and ion-exchange adsorption.

    Science.gov (United States)

    da Silva, Clovis Sacardo; Cuel, Maressa Fabiano; Barreto, Verônica Orlandin; Kwong, Wu Hong; Hokka, Carlos O; Barboza, M

    2012-02-15

    The clavulanic acid is a substance which inhibits the β-lactamases used with penicillins for therapeutic treatment. After the fermentation, by-products of low molecular weight such as amino acids lysine, histidine, proline and tyrosine are present in the fermented broth. To remove these impurities the techniques of extraction by an aqueous two-phase system of 17% polyethylene glycol molecular weight 600 and 15% potassium phosphate were used for a partial purification. A subsequent ion-exchange adsorption was used for the recuperation of the clavulanic acid of the top phase and purification getting a concentration factor of 2 and purification of 100% in relation to the amino acids lysine, histidine, proline and tyrosine.

  8. Crown-Ether Derived Graphene Hybrid Composite for Membrane-Free Potentiometric Sensing of Alkali Metal Ions

    DEFF Research Database (Denmark)

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    2016-01-01

    surface coverage is achieved by the introduction of a flexible linking molecule. The resulting hybrid composite is highly stable and is capable of detecting potassium ions down to micromolar ranges with a selectivity over other cations (including Ca2+, Li+, Na+, NH4+) at concentrations up to 25 m......We report the design and synthesis of newly functionalized graphene hybrid material that can be used for selective membrane-free potentiometric detection of alkali metal ions, represented by potassium ions. Reduced graphene oxide (RGO) functionalized covalently by 18-crown[6] ether with a dense...

  9. High-throughput optical sensing of nucleic acids in a nanopore array

    Science.gov (United States)

    Huang, Shuo; Romero-Ruiz, Mercedes; Castell, Oliver K.; Bayley, Hagan; Wallace, Mark I.

    2016-01-01

    Protein nanopores such as α-hemolysin and MspA can potentially be used to sequence long strands of DNA quickly and at low cost. In order to provide high-speed sequencing, large arrays of nanopores are required that allow the nanopores to individually addressed, but current nanopore sequencing methods rely on ionic current measurements and such methods are likely to prove difficult to scale up. Here, we show that, by optically encoding the ionic flux through protein nanopores, the discrimination of nucleic acid sequences and the detection of sequence-specific nucleic acid binding events can be parallelized. We make optical recordings at a density of ~104 nanopores per mm2 in a single droplet interface bilayer. Nanopore blockades can discriminate between DNAs with sub-pA equivalent resolution, and specific miRNA sequences can be identified by differences in unzipping kinetics. By creating an array of 2500 bilayers with a micro-patterned hydrogel chip, we are also able to load different samples into specific bilayers, suitable for high-throughput nanopore recording. PMID:26322943

  10. High-throughput optical sensing of nucleic acids in a nanopore array.

    Science.gov (United States)

    Huang, Shuo; Romero-Ruiz, Mercedes; Castell, Oliver K; Bayley, Hagan; Wallace, Mark I

    2015-11-01

    Protein nanopores such as α-haemolysin and Mycobacterium smegmatis porin A (MspA) can be used to sequence long strands of DNA at low cost. To provide high-speed sequencing, large arrays of nanopores are required, but current nanopore sequencing methods rely on ionic current measurements from individually addressed pores and such methods are likely to prove difficult to scale up. Here we show that, by optically encoding the ionic flux through protein nanopores, the discrimination of nucleic acid sequences and the detection of sequence-specific nucleic acid hybridization events can be parallelized. We make optical recordings at a density of ∼10(4) nanopores per mm(2) in a single droplet interface bilayer. Nanopore blockades can discriminate between DNAs with sub-picoampere equivalent resolution, and specific miRNA sequences can be identified by differences in unzipping kinetics. By creating an array of 2,500 bilayers with a micropatterned hydrogel chip, we are also able to load different samples into specific bilayers suitable for high-throughput nanopore recording. PMID:26322943

  11. Naked eye sensor on polyvinyl chloride platform of chromo-ionophore molecular assemblies: A smart way for the colorimetric sensing of toxic metal ions

    International Nuclear Information System (INIS)

    We demonstrate the possibility of fabricating a simple, naked eye colorimetric sensor miniature, using chromo-ionophore molecular assemblies anchored on polyvinyl chloride (PVC) surface. The ion-sensing probe (4-n-dodecyl-6-(2-thiazolylazo)-resorcinol) provides a better efficiency with PVC platform in developing a series of colour transitions, while targeting trace levels of Cd2+, Pb2+ and Hg2+. The physical properties of the film sensor are controlled by measuring the probe isotherm plot. The surface morphology and molecular composition of the solid-state optical sensor are characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The changes in sensor's optical intensity and its response time for the target analytes are followed by absorption spectroscopy. High speed of response (t ≤ 5 min) and confidence in determination of analytes from chemically complex matrices has been achieved, using simulated synthetic mixtures and spiked real environmental samples, with a relative standard deviation of 2+, Pb2+ and Hg2+ ions, respectively. The sensor strips are reversible and reusable without any change in the sensing efficiency, up to four cycles. The signal response observed with the proposed method is consistent between sensors, and also are stable over time

  12. 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)

    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)

  13. Review on aggregation of acid extractants in solvent extraction of metal ions: remark on the general model

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The aggregation behavior of various acid extractants in the solvent extraction systems of metal ions is re-examined and explained according to knowledge obtained in recent work. The conclusions are as follows. (1) Complexes formed by the extractants and metal ions can form reversed micelles in organic diluents, depending on the microstructures of the complexes. The dimers of the acid extractant cannot percolate to the metal-extractant aggregates, and the acid-salt complexes are always formed in the aggregates. The reversed micelles or the W/O microemulsions formed by different species cannot be associated with each other to form a unified aggregate. (2) In solvent extraction systems, hydration of the extractants and metal ions can be considered as the driving force of forming reversed micelles. (3) Information of the first approach to the insight of the bicontinuous microemulsion of NaDEHP shows that various components in the aqueous phase behave confined and very similar to the typical AOT/n-heptane W/O microemulsions. (4) In the extraction of lanthanide ions by the W/O microemulsion of sodium naphthenate, the saponification is a process of forming reversed micelle or W/O microemulsion, while the extraction step is a process of destroying reversed micelles or W/O microemulsion droplets.

  14. Involvements of chloride ion in decolorization of Acid Orange 7 by activated peroxydisulfate or peroxymonosulfate oxidation

    Institute of Scientific and Technical Information of China (English)

    Ping Wang; Shiying Yang; Liang Shan; Rui Niu; Xueting Shao

    2011-01-01

    The effects of chloride anion (C1-) (up to 1.0 mol/L) on the decolorization of a model compound,azo dye Acid Orange 7 (AO7),by sulfate radical (SO4-*) based-peroxydisulfate (PS) or peroxymonosulfate (PMS) oxidation under various activated conditions (UV254 nm/PS,Thermal (70℃/PS,UV254 nm/PMS,Co2+/PMS) were investigated.Methanol and NH4+ were used as quenching reagents to determine the contributions of active chlorine species (dichloride radical (Cl2-*) and hypochlorous acid (HClO)).The results indicated that the effects of Cl- on the reaction mechanism were different under various activated conditions.For UV/PS and Thermal/PS,the inhibition tendency became more clear as the Cl-concentration increased,probably due to the reaction between Cl- and SO4-* and the generation of Cl2-* or HClO.For UV/PMS,Cl- did not exhibit inhibition when the concentration was below 0.1 mol/L.As Cl-concentration reached to 1.0 mol/L,the decolorization rate of AO7 was,however,accelerated,possibly because PMS directly reacts with C1- to form HC1O.For Co2+/PMS,Cl- exhibited a significant inhibiting effect even at low concentration (≤ 0.01 mol/L).When Cl- concentration exceeded 0.1 mol/L,the activation of PMS by Co2+ was almost completely inhibited.Under this condition,HClO maybe played a major role in decolorization of AO7.The results implicated that chloride ion is an important factor in SO4-*-based degradation of organic contamination in chloride-containing water.

  15. An online monitoring system for atmospheric nitrous acid (HONO) based on stripping coil and ion chromatography

    Institute of Scientific and Technical Information of China (English)

    Peng Cheng; Yafang Cheng; Keding Lu; Hang Su; Qiang Yang; Yikan Zou; Yanran Zhao

    2013-01-01

    A new instrument for measuring atmospheric nitrous acid (HONO) was developed,consisting of a double-wail glass stripping coil sampler coupled with ion chromatography (SC-IC).SC-IC is featured by small size (50 × 35 × 25 cm) and modular construction,including three independent parts:the sampling unit,the transfer and supporting unit,and the detection unit.High collection efficiency (> 99%) was achieved with 25 μmol/L Na2CO3 as absorption solution even in the presence of highly acidic compounds.This instrument has a detection limit of 8 pptv at 15 min time resolution,with a measurement uncertainty of 7%.Potentiai interferences from NOx,NO2+SO2,NO2+VOCs,HONO+O3,HNO3,peroxyacetyl nitrite (PAN) and particle nitrite were quantified in laboratory studies and were found to be insignificant under typical atmospheric conditions.Within the framework of the 3C-STAR project,inter-comparison between the SC-IC and LOPAP (long path liquid absorption photometer) was conducted at a rurai site in the Pearl River Delta.Good agreement was achieved between the two instruments over three weeks.Both instruments determined a clear diurnai profile of ambient HONO concentrations from 0.1 to 2.5 ppbv.However,deviations were found for low ambient HONO concentrations (i.e.<0.3 ppbv),which cannot be explained by previous investigated interference species.To accurately determine the HONO budget under illuminated conditions,more intercomparison of HONO measurement techniques is still needed in future studies,especiaily at low HONO concentrations.

  16. 9-Benzylidene-9H-fluorene Derivatives Linked to Monoaza- 15-crown-5: Synthesis and Metal Ion Sensing

    Institute of Scientific and Technical Information of China (English)

    曹靖; 李阳; 冯俊香

    2012-01-01

    Two kinds of novel styryl chemosensory 2-FMNC and 3-FMNC, were designed and synthesized by an apporiate introduction of 9-benzylidene-9H-fluorene group as fluorophore with the aim at avoiding photoisomerisation. These 9-benzylidene-9H-fluorene derivatives showed the similar selectivity and sensitivity upon addition of metal ions. The sensitivity of FMNC to alkaline earth metal ions was Ba2+〉 Sr2+〉Ca2+≈Mg2+.

  17. 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.

  18. Determination of catecholamines by ion chromatography coupled to acidic potassium permanganate chemiluminescence detection

    Institute of Scientific and Technical Information of China (English)

    Hong Wei Wu; Mei Lan Chen; Dan Shou; Yan Zhu

    2012-01-01

    A simple,fast,sensitive,highly selective and eco-friendly analytical method for the determination of catecholamines in human urine by ion chromatography (IC) with chemiluminescence (CL) detection was described in this paper.Using 12 mmoi/L H2SO4 without any organic additive as eluent,three catecholamines including epinephrine (EP),norepinephrine (NE) and dopamine (DA)were well separated on a cation-exchange column.The CL detection was based on the reaction of analytes with acidic potassium permanganate in the presence of formaldehyde as an enhancer.The absence of methanol and acetonitrile in eluent made the proposed method more sensitive and eco-friendly.Under the optimal conditions,the linear range of the proposed method was in the range of 0.02-0.5 μg/mL.The limit of detection (LOD) was in the range of 0.6 and 5.1 μg/L.The relative standard deviations (RSD) for 0.1 μg/mL mixed standard solution were in the range of 0.8-1.9% (n =11).The method has been applied to the determination of catecholamines in human urine successfully.Excellent spiked recoveries were achieved for catecholamines ranged from 91.2% to 112.7%.

  19. Ion chromatographic analysis of tetracyclines using polymeric column and acidic eluent.

    Science.gov (United States)

    Ding, X; Mou, S

    2000-11-01

    High-performance ion chromatography (HPIC) is first successfully used to analyze tetracycline antibiotics (TCs) in this work. The TCs are well separated on a solvent compatible polymeric cation-exchange column within 12 min. Isocratic elution with acetonitrile-hydrochloride is very advantageous for routine analysis. HPIC may be seen as a specific variant of the more common high-performance liquid chromatography (HPLC) for water-soluble and polar pharmaceuticals with low hydrophobicity. The detection limits (signal-to-noise ratio=3:1) of oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC), doxycycline (DC) are 10, 10, 20 and 20 microg l(-1), respectively. Samples are prepared by vortex mixing with an ethylenediaminetetraacetic acid disodium salt (Na2EDTA)-McIlvaine buffer (pH 4.0) solution and the mixture filtrates through a molecular weight cut-off filter. The method has been successfully applied to monitor the OTC removal rate through every reactor in the process of OTC manufacturing wastewater treatment by bio-chemical technology. It is also applicable to determine the TCs residues in milk and milk powder with satisfying results. PMID:11128204

  20. Dissolution kinetics of manganese dioxide ore in sulfuric acid in the presence of ferrous ion

    International Nuclear Information System (INIS)

    In this paper, kinetics of reductive leaching of manganese dioxide ore by ferrous ion in sulfuric acid media has been examined. Experimental results show that increasing temperature from 20 to 60 degC and decreasing are particle size from -16+20 to -60+100 mesh considerably enhance both the dissolution rate and efficiency. Molar ratios of Fe2+/MnO2 and H2SO4/MnO2 in excess to the stoichiometric amounts were needed for successful manganese dissolution. Under the optimum condition (are particle size of -60+100 mesh, Fe2+/MnO2 molar ratio of 3.0, H2SO4/MnO2 molar ratio of 2.0) manganese could be extracted with 95% efficiency by 20 minutes leaching at room temperature. A kinetic analysis based on dimensionless time method showed that shrinking core -ash diffusion control model fits the experimental results reasonably well. Value of activation energy was found to be 28.1 kJ/mole for the proposed mechanism

  1. Uranyl ion complexation by citric and citramalic acids in the presence of di-amines

    International Nuclear Information System (INIS)

    Uranyl nitrate reacts with citric (H4cit) or D-(-)-citramalic (H3citml) acids under mild hydrothermal conditions and in the presence of di-amines to give different complexes which are all characterized by the presence of 2:2 uranyl/poly-carboxylate di-anionic dimers or of polymeric chains based on the same dimeric motif. Each uranium ion is chelated by the two ligands through the alkoxide and the α- or β-carboxylate groups, the second β-carboxylic group in citrate being uncoordinated. The uranium coordination sphere is completed by either a water molecule or the β-carboxylate group of a neighboring unit, thus giving zero- or one-dimensional assemblages, respectively. The evidence for [UO2(Hcit)]2 dimers in the solid state confirms previous results from potentiometric and EXAFS measurements on solutions. Depending on the diamine used (DABCO, 2,2'- and 4,4'-bipyridine, [2.2.2]cryptand) and its ability to form divergent hydrogen bonds or not, different uranyl/poly-carboxylate topologies are obtained, thus evidencing template effects, and extended hydrogen bonding gives two- or three-dimensional assemblages. These results, together with those previously obtained with NaOH as a base, add to the knowledge of the uranyl/citrate system, which is much investigated for its environmental relevance. (author)

  2. Adsorption properties of silica surface-grafted with a salicylhydroxamic acid-functionalized polymer toward lead ions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ruixin; Xie, Meina; Wang, Hongjing; Shi, Xiaohui; Lei, Caiping [North University of China, Taiyuan (China)

    2016-03-15

    Salicylhydroxamic acid (SHA), functionalized composite chelating adsorbing material SHA-PHEMA/SiO{sub 2}, was prepared through the nucleophilic substitution reaction of 5-chloromethyl-salicylhydroxamic acid with poly (2- hydroethyl methacrylate) (PHEMA) modified silica gel particles PHEMA/SiO{sub 2}. The SHA-PHEMA/SiO{sub 2} composites were characterized by FT-IR, scanning electron microscopy, X-ray photoelectron spectroscopy and nitrogen absorption. The adsorption behavior, adsorption thermodynamic, and adsorption mechanism of SHA-PHEMA/SiO{sub 2} for Pb2+ ions were studied, and the pH value of the medium on the adsorption property and chelating adsorption ability of SHA-PHEMA/SiO{sub 2} for Pb2{sup +} ions was also investigated. The experimental results show that SHA-PHEMA/SiO{sub 2} possesses strong chelating adsorption ability for Pb2{sup +} ions, and the adsorption capacity for Pb2{sup +} ions at 308K reached 57 mg/g. The adsorption process is a chemical adsorption process driven by entropy, and the adsorption capacity increases with rising temperature. In pH range that can inhibit the hydrolysis of heavy metal ions, increasing the pH value of the medium strengthens the adsorption ability of SHA-PHEMA/SiO{sub 2} toward Pb2{sup +} ions. The adsorption behavior is monomolecular and follows Langmuir isotherm. The adsorption capacity is almost the same after ten consecutive adsorption- desorption experiments of SHA-PHEMA/SiO{sub 2} for Pb2{sup +} ions, indicating that SHA-PHEMA/SiO{sub 2} has excellent elution property and reusability.

  3. Hydrogen-ion titrations of amino acids and proteins in solutions containing concentrated electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Fergg, F. [Technische Universitaet Muenchen (Germany); Kuehner, D.E.; Blanch, H.W.; Prausnitz, J.M. [Lawrence Berkeley Lab., CA (United States)

    1994-12-01

    This report describes a first attempt to quantify the net charge as a function of solution pH for lysozyme and {alpha}-chymotrypsin at 0.1 M, 1.0 M and 3.0 M ionic strength, (IS). The calculations are based on the residue (titratable group) pK{sub a}`s in the amino-acid sequence of the protein. To determine these pK{sub a}`s, a simple theory was used which assumes that the pK{sub a}`s are independent from each other in the protein and are equal to their pK{sub a} values in free amino-acid solution (Independent-Site Theory, IST). Residue pK{sub a}`s were obtained from amino-acid hydrogen-ion titrations at three different KCl concentrations corresponding to 0.1M, 1.0M and 3.0M ionic strength. After construction of a suitable apparatus, the experimental procedure and data reduction were computerized to perform a large number of titrations. Most measured pK{sub a}`s showed high reproducibility (the difference of pK{sub a} values observed between two experiments was less than 0.05). For IS = 0.1M, observed pK{sub a}`s agreed with literature values to within a few hundredths of a pH unit. Furthermore, the ionic-strength dependence of the pK{sub a}`s followed the trends reported in the literature, viz. pK{sub a} values decrease with increasing ionic strength until they reach a minimum at about IS = 0.5M. At still higher IS, pK{sub a}`s increase as the ionic strength rises to 3M. The known pK{sub a}`s of all titratable groups in a protein were used with the IST to give a first approximation of how the protein net charge varies with pH at high ionic strength. A comparison of the titration curves based on the IST with experimental lysozyme and {alpha}-chymotrypsin titration data indicates acceptable agreement at IS = 0.1M. However, comparison of measured and calculated titration curves at IS = 1M and IS = 3M indicates only quantitative agreement.

  4. Lead-acid and lithium-ion batteries for the Chinese electric bike market and implications on future technology advancement

    Science.gov (United States)

    Weinert, Jonathan X.; Burke, Andrew F.; Wei, Xuezhe

    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.

  5. 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.

  6. Electrochemical sensing of bisphenol A based on polyglutamic acid/amino-functionalised carbon nanotubes nanocomposite

    International Nuclear Information System (INIS)

    This study reports the application of polyglutamate acid (PGA) and amino-functionalised carbon nanotube (MWCNT-NH2) nanocomposite modified glassy carbon electrodes for the electrochemical determination of bisphenol A (BPA). The PGA/MWCNT-NH2 nanocomposite exhibits excellent electrocatalytic activity for the oxidation of BPA by substantially enhancing the current response and decreasing the BPA oxidation overpotential. The composite modified glass carbon electrode (GCE) exhibited good performance for detecting BPA due to the enhanced electron transfer kinetics and large active surface area. The effective enrichment of BPA is due to the carboxyl and amino groups on the composite. Under the optimised conditions and according to the results from differential pulse voltammetry (DPV), the BPA oxidation current is linear in a concentration range of 0.1 to 10 μM (R = 0.998), and the detection limit was determined to be 0.02 μM (S/N = 3). The proposed sensors were successfully employed to determine BPA in real plastic products, and the recoveries were between 95% and 108%. This strategy might enable more opportunities for the electrochemical determination of BPA in practical applications

  7. Farnesoid X receptor, the bile acid sensing nuclear receptor, in liver regeneration

    Directory of Open Access Journals (Sweden)

    Guodong Li

    2015-03-01

    Full Text Available The liver is unique in regenerative potential, which could recover the lost mass and function after injury from ischemia and resection. The underlying molecular mechanisms of liver regeneration have been extensively studied in the past using the partial hepatectomy (PH model in rodents, where 2/3 PH is carried out by removing two lobes. The whole process of liver regeneration is complicated, orchestrated event involving a network of connected interactions, which still remain fully elusive. Bile acids (BAs are ligands of farnesoid X receptor (FXR, a nuclear receptor of ligand-activated transcription factor. FXR has been shown to be highly involved in liver regeneration. BAs and FXR not only interact with each other but also regulate various downstream targets independently during liver regeneration. Moreover, recent findings suggest that tissue-specific FXR also contributes to liver regeneration significantly. These novel findings suggest that FXR has much broader role than regulating BA, cholesterol, lipid and glucose metabolism. Therefore, these researches highlight FXR as an important pharmaceutical target for potential use of FXR ligands to regulate liver regeneration in clinic. This review focuses on the roles of BAs and FXR in liver regeneration and the current underlying molecular mechanisms which contribute to liver regeneration.

  8. 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.

  9. The effect of acid-base clustering and ions on the growth of atmospheric nano-particles

    Science.gov (United States)

    Lehtipalo, Katrianne; Rondo, Linda; Kontkanen, Jenni; Schobesberger, Siegfried; Jokinen, Tuija; Sarnela, Nina; Kürten, Andreas; Ehrhart, Sebastian; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Sipilä, Mikko; Yli-Juuti, Taina; Duplissy, Jonathan; Adamov, Alexey; Ahlm, Lars; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Downard, Andrew J.; Dunne, Eimear M.; Flagan, Richard C.; Guida, Roberto; Hakala, Jani; Hansel, Armin; Jud, Werner; Kangasluoma, Juha; Kerminen, Veli-Matti; Keskinen, Helmi; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Kupiainen-Määttä, Oona; Laaksonen, Ari; Lawler, Michael J.; Leiminger, Markus; Mathot, Serge; Olenius, Tinja; Ortega, Ismael K.; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud; Rissanen, Matti P.; Ruuskanen, Taina; Santos, Filipe D.; Schallhart, Simon; Schnitzhofer, Ralf; Simon, Mario; Smith, James N.; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Tomé, António; Vaattovaara, Petri; Vehkamäki, Hanna; Vrtala, Aron E.; Wagner, Paul E.; Williamson, Christina; Wimmer, Daniela; Winkler, Paul M.; Virtanen, Annele; Donahue, Neil M.; Carslaw, Kenneth S.; Baltensperger, Urs; Riipinen, Ilona; Curtius, Joachim; Worsnop, Douglas R.; Kulmala, Markku

    2016-05-01

    The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. We bring these observations into a coherent framework and discuss their significance in the atmosphere.

  10. 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....

  11. TASK channels in arterial chemoreceptors and their role in oxygen and acid sensing.

    Science.gov (United States)

    Buckler, Keith J

    2015-05-01

    Arterial chemoreceptors play a vital role in cardiorespiratory control by providing the brain with information regarding blood oxygen, carbon dioxide, and pH. The main chemoreceptor, the carotid body, is composed of sensory (type 1) cells which respond to hypoxia or acidosis with a depolarising receptor potential which in turn activates voltage-gated calcium entry, neurosecretion and excitation of adjacent afferent nerves. The receptor potential is generated by inhibition of Twik-related acid-sensitive K(+) channel 1 and 3 (TASK1/TASK3) heterodimeric channels which normally maintain the cells' resting membrane potential. These channels are thought to be directly inhibited by acidosis. Oxygen sensitivity, however, probably derives from a metabolic signalling pathway. The carotid body, isolated type 1 cells, and all forms of TASK channel found in the type 1 cell, are highly sensitive to inhibitors of mitochondrial metabolism. Moreover, type1 cell TASK channels are activated by millimolar levels of MgATP. In addition to their role in the transduction of chemostimuli, type 1 cell TASK channels have also been implicated in the modulation of chemoreceptor function by a number of neurocrine/paracrine signalling molecules including adenosine, GABA, and serotonin. They may also be instrumental in mediating the depression of the acute hypoxic ventilatory response that occurs with some general anaesthetics. Modulation of TASK channel activity is therefore a key mechanism by which the excitability of chemoreceptors can be controlled. This is not only of physiological importance but may also offer a therapeutic strategy for the treatment of cardiorespiratory disorders that are associated with chemoreceptor dysfunction.

  12. Micro/nanofabrication of poly({sub L}-lactic acid) using focused ion beam direct etching

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, Tomoko Gowa; Nagasawa, Naotsugu; Taguchi, Mitsumasa [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Hinata, Toru; Washio, Masakazu [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Oshima, Akihiro; Tagawa, Seiichi [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2013-10-14

    Micro/nanofabrication of biocompatible and biodegradable poly({sub L}-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachment properties.

  13. Poly (acrylic acid sodium) grafted carboxymethyl cellulose as a high performance polymer binder for silicon anode in lithium ion batteries

    OpenAIRE

    Liangming Wei; Changxin Chen; Zhongyu Hou; Hao Wei

    2016-01-01

    The design of novel binder systems is required for the high capacity silicon (Si) anodes which usually undergo huge volume change during the charge/discharge cycling. Here, we introduce a poly (acrylic acid sodium)-grafted-carboxymethyl cellulose (NaPAA-g-CMC) copolymer as an excellent binder for Si anode in lithium ion batteries (LIBs). The NaPAA-g-CMC copolymer was prepared via a free radical graft polymerization method by using CMC and acrylic acid as precursors. Unlike the linear, one-dim...

  14. Strong Relationships in Acid-Base Chemistry - Modeling Protons Based on Predictable Concentrations of Strong Ions, Total Weak Acid Concentrations, and pCO2

    DEFF Research Database (Denmark)

    Ring, Troels; Kellum, John A

    2016-01-01

    confirmed the relationship between charged species we then examine some of the classical and recent literature concerning the importance of charge balance. We conclude that focusing on the charges which are predictable such as strong ions and total concentrations of weak acids leads to new insights......Understanding acid-base regulation is often reduced to pigeonholing clinical states into categories of disorders based on arterial blood sampling. An earlier ambition to quantitatively explain disorders by measuring production and elimination of acid has not become standard clinical practice....... Seeking back to classical physical chemistry we propose that in any compartment, the requirement of electroneutrality leads to a strong relationship between charged moieties. This relationship is derived in the form of a general equation stating charge balance, making it possible to calculate [H+] and p...

  15. Comparison of high-performance ion chromatography and absorptiometric methods for the determination of phytic acid in food samples

    OpenAIRE

    Talamond, Pascale; Gallon, Georges; Guyot, Jean-Pierre; Mbome Lape, I.; Trèche, Serge

    1998-01-01

    The objective of this paper consists in defining the interest of a new high-performance ion chromatography method (HPIC) with a chemically suppressed conductivity detector for phytic acid determination in food samples. Firstly, accuracy and precision of the HPIC method were measured. Secondly, the HPIC method and a classical absorptiometric method were compared. The HPIC method was more sensitive and selective than the absorptiometric method which led to a 27% overestimation of the phytic aci...

  16. Studies on high γ-aminobutyric acid-producing monascus purpureus which breeding with heavy ion beam radiation

    International Nuclear Information System (INIS)

    γ-Aminobutyric Acid (GABA) is a kind of nonprotein amino acid, which is reported to antihypertension, tranquilization, improve liver function, prevent obesity and avoid senile dementia, etc., and is an important effective component in health products. In this study, Monascus Purpureus spores were radiated with 96 MeV/u, LET=28.12 keV/μm 12C6+ ion beams. Doses were set as 20, 50 and 80 Gy, respectively. The experiments were run as follows: preparation of monospore suspension → irradiated with heavy ion beam → diluted and spread on dish → screening and stored in inclined plane → shaking culture → GABA extraction → GABA concentration determined by paper chromatography. One stable high productive strain HQ06 was obtained in this study. The content of GABA in HQ06 was 2.50±0.04 mg/ml, 3.7±1.7% higher than that in control (which was 2.41±0.03 mg/ml). Results showed that it is feasible for breeding high GABA producing strains with heavy ion beam radiation, and the heavy ion beam is a kind of effective mutation source. Further studies should be done for breeding much higher productive strains to satisfy the demands of industry. (authors)

  17. Impact of citric acid and calcium ions on acid solubilization of mechanically separated turkey meat: effect on lipid and pigment content.

    Science.gov (United States)

    Hrynets, Y; Omana, D A; Xu, Y; Betti, M

    2011-02-01

    Increased demand for poultry products has resulted in an increased availability of by-products, such as the neck, back, and frame, that can be processed into mechanically separated poultry meat. The major problems with mechanically separated poultry meat are its high lipid content, color instability, and high susceptibility to lipid oxidation. The present work was undertaken to determine the effect of different concentrations of citric acid and calcium ions on protein yield, color characteristics, and lipid removal from protein isolates prepared using an acid-aided extraction process. Six levels of citric acid (0, 2, 4, 6, 8, and 10 mmol/L) and 2 levels of calcium chloride (0 and 8 mmol/L) were examined. The entire experiment was replicated 3 times, resulting in 36 extractions (3 × 6 × 2). The highest (P citric acid. In general, all the combinations removed an average of 90.8% of the total lipids from mechanically separated turkey meat, ranging from 86.2 to 94.7%. The lowest amount (1.14%) of total lipids obtained was for samples treated with 4 mmol/L of citric acid. Maximum removal of neutral lipids (96.5%) and polar lipids (96.4%) was attained with the addition of 6 and 2 mmol/L of citric acid, respectively. Polar lipid content was found to be significantly (P = 0.0045) affected by the presence of calcium chloride. The isolated proteins were less (P citric acid. Addition of calcium chloride had a negative effect on total pigment content. The study revealed that acid extractions with the addition of citric acid resulted in substantial removal of lipids and pigments from mechanically separated turkey meat, improved stability of the recovered proteins against lipid oxidation, and appreciable protein recovery yields.

  18. Cis-2-dodecenoic acid signal modulates virulence of Pseudomonas aeruginosa through interference with quorum sensing systems and T3SS

    Science.gov (United States)

    2013-01-01

    Background Cis-2-dodecenoic acid (BDSF) is well known for its important functions in intraspecies signaling in Burkholderia cenocepacia. Previous work has also established an important role of BDSF in interspecies and inter-kingdom communications. It was identified that BDSF modulates virulence of Pseudomonas aeruginosa. However, how BDSF interferes with virulence of P. aeruginosa is still not clear. Results We report here that BDSF mediates the cross-talk between B. cenocepacia and P. aeruginosa through interference with quorum sensing (QS) systems and type III secretion system (T3SS) of P. aeruginosa. Bioassay results revealed that exogenous addition of BDSF not only reduced the transcriptional expression of the regulator encoding gene of QS systems, i.e., lasR, pqsR, and rhlR, but also simultaneously decreased the production of QS signals including 3-oxo-C12-HSL, Pseudomonas quinolone signal (PQS) and C4-HSL, consequently resulting in the down-regulation of biofilm formation and virulence factor production of P. aeruginosa. Furthermore, BDSF and some of its derivatives are also capable of inhibiting T3SS of P. aeruginosa at a micromolar level. Treatment with BDSF obviously reduced the virulence of P. aeruginosa in both HeLa cell and zebrafish infection models. Conclusions These results depict that BDSF modulates virulence of P. aeruginosa through interference with QS systems and T3SS. PMID:24134835

  19. Improvement of L(+)-Lactic Acid Production of Rhizopus Oryzae by Low-Energy Ions and Analysis of Its Mechanism

    Institute of Scientific and Technical Information of China (English)

    GE Chunmei; YANG Yingge; FAN Yonghong; LI Wen; PAN Renrui; ZHENG Zhiming; YU Zengliang

    2008-01-01

    The wild type strain Rhizopus oryzae PW352 was mutated by means of nitrogen ion implantation (15 keV, 7.8 × 104 ~ 2.08 × 105 ions/cm2) to find an industrial strain with a higher L(+)-lactic acid yield, and two mutants RE3303 and RF9052 were isolated. In order to discuss the mechanism primarily,Lactate Dehydrogenase of Rhizopus oryzae was studied. While the two mutants produced L(+)-lactic acid by 75% more than the wild strain did, their specific activity of Lactate Dehydrogenase was found to be higher than that in the wild strain. The optimum temperature of Lactate Dehydrogenase in Rhizopus oryzae RF9052 was higher. Compared to the wild strain, the Michaelis constant (Km) value of Lactate Dehydrogenase in the mutants was Changed. All these changes show that L(+)-lactic acid production has a correlation with the specific activity of Lactate Dehydrogenase. The low-energy ions, implanted into the strain, may improve the specific activity of Lactate Dehydrogenase by influencing its gene structure and protein structure.

  20. Central metal ion exchange in a coordination polymer based on lanthanide ions and di(2-ethylhexyl)phosphoric acid: exchange rate and tunable affinity.

    Science.gov (United States)

    Tasaki-Handa, Yuiko; Abe, Yukie; Ooi, Kenta; Tanaka, Mikiya; Wakisaka, Akihiro

    2014-01-01

    In this paper the exchange of lanthanide(III) ions (Ln(3+)) between a solution and a coordination polymer (CP) of di(2-ethylhexyl)phosphoric acid (Hdehp), [Ln(dehp)3], is studied. Kinetic and selectivity studies suggest that a polymeric network of [Ln(dehp)3] has different characteristics than the corresponding monomeric complex. The reaction rate is remarkably slow and requires over 600 h to reach in nearly equilibrium, and this can be explained by the polymeric crystalline structure and high valency of Ln(3+). The affinity of the exchange reaction reaches a maximum with the Ln(3+) possessing an ionic radius 7% smaller than that of the central Ln(3+), therefore, the affinity of the [Ln(dehp)3] is tunable based on the choice of the central metal ion. Such unique affinity, which differs from the monomeric complex, can be explained by two factors: the coordination preference and steric strain caused by the polymeric structure. The latter likely becomes predominant for Ln(3+) exchange when the ionic radius of the ion in solution is smaller than the original Ln(3+) by more than 7%. Structural studies suggest that the incoming Ln(3+) forms a new phase though an exchange reaction, and this could plausibly cause the structural strain.

  1. Complete Transmetalation in a Metal-Organic Framework by Metal Ion Metathesis in a Single Crystal for Selective Sensing of Phosphate Ions in Aqueous Media.

    Science.gov (United States)

    Asha, K S; Bhattacharjee, Rameswar; Mandal, Sukhendu

    2016-09-12

    A complete transmetalation has been achieved on a barium metal-organic framework (MOF), leading to the isolation of a new Tb-MOF in a single-crystal (SC) to single-crystal (SC) fashion. It leads to the transformation of an anionic framework with cations in the pore to one that is neutral. The mechanistic studies proposed a core-shell metal exchange through dissociation of metal-ligand bonds. This Tb-MOF exhibits enhanced photoluminescence and acts as a selective sensor for phosphate anion in aqueous medium. Thus, this work not only provides a method to functionalize a MOF that can have potential application in sensing but also elucidates the formation mechanism of the resulting MOF.

  2. Ion-exchange equilibria of tungsten in the ionite-sodium sulfate sulfuric acid solution system

    International Nuclear Information System (INIS)

    Ion-exchange equilibrium in the system macroporous ionite-Na2WO4-Na2SO4-H2O(H2SO4) are studied by the methods of IR- and absorption spectroscopy, electron microscopy and mercury porometry to develop methods for tungsten selective extraction from solutions mentioned. It is ascertained that amine-containing macroporous anionites features a high exchange capacity towards tungsten ions in sulfate solutions at pH 2.5-5.5. The anionites permit a complete separation of tungsten ions from sulfate ions and preparation of pure tungsten salts

  3. Ion mobility spectrometry-mass spectrometry examination of the structures, stabilities, and extents of hydration of dimethylamine-sulfuric acid clusters.

    Science.gov (United States)

    Thomas, Jikku M; He, Siqin; Larriba-Andaluz, Carlos; DePalma, Joseph W; Johnston, Murray V; Hogan, Christopher J

    2016-08-17

    We applied an atmospheric pressure differential mobility analyzer (DMA) coupled to a time-of-flight mass spectrometer to examine the stability, mass-mobility relationship, and extent of hydration of dimethylamine-sulfuric acid cluster ions, which are of relevance to nucleation in ambient air. Cluster ions were generated by electrospray ionization and were of the form: [H((CH3)2NH)x(H2SO4)y](+) and [(HSO4)((CH3)2NH)x(H2SO4)y](-), where 4 ≤ x ≤ 8, and 5 ≤ y ≤ 12. Under dry conditions, we find that positively charged cluster ions dissociated via loss of both multiple dimethylamine and sulfuric acid molecules after mobility analysis but prior to mass analysis, and few parent ions were detected in the mass spectrometer. Dissociation also occurred for negative ions, but to a lesser extent than for positive ions for the same mass spectrometer inlet conditions. Under humidified conditions (relative humidities up to 30% in the DMA), positively charged cluster ion dissociation in the mass spectrometer inlet was mitigated and occurred primarily by H2SO4 loss from ions containing excess acid molecules. DMA measurements were used to infer collision cross sections (CCSs) for all identifiable cluster ions. Stokes-Millikan equation and diffuse/inelastic gas molecule scattering predicted CCSs overestimate measured CCSs by more than 15%, while elastic-specular collision model predictions are in good agreement with measurements. Finally, cluster ion hydration was examined by monitoring changes in CCSs with increasing relative humidity. All examined cluster ions showed a modest amount of water molecule adsorption, with percentage increases in CCS smaller than 10%. The extent of hydration correlates directly with cluster ion acidity for positive ions. PMID:27485283

  4. Sony Co., Ltd.: An outlook is made for merchandising of the manganese acid lithium ion battery; Mangansan richiumuion denchi no shohinka ni medo

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    Sony Co., Ltd. sells the manganese acid lithium ion battery that a battery is 1 by 2 as to the next generation lithium ion during 99 years. It is characteristics that a price is restrained because manganese is used for the proper pole material instead of cobalt of the rare metal. It becomes mass production by Koriyama factory where a lithium ion battery is being manufactured improving an existent production line. It is seen when some percents of manufacture cost goes down more than cobalt acid battery of news file before. A manganese acid lithium ion battery uses manganese acid lithium for the proper pole of the battery. The efficiency of the charge of the usual lithium ion battery is good, and composition is easy, and uses cobalt acid lithium, which is easy to produce. One side where a material fee is cheap, the stability at the high temperature of manganese acid is low, and composition is difficult. Only NEC Moli Energy corporation who is the subsidiary company of NEC succeeds in the mass production. NEC Moli Energy corporation is extending market share by the price competition power. It seems to have the possibility that manganese acid becomes the main force with a battery by two by new entering of Sony Co., Ltd. of the lithium ion battery extreme big enterprises. (translated by NEDO)

  5. Ion binding by humic and fulvic acids: A computational procedure based on functional site heterogeneity and the physical chemistry of polyelectrolyte solutions

    International Nuclear Information System (INIS)

    Ion binding equilibria for humic and fulvic acids are examined from the point of view of functional site heterogeneity and the physical chemistry of polyelectrolyte solutions. A detailed explanation of the potentiometric properties of synthetic polyelectrolytes and ion-exchange gels is presented first to provide the basis for a parallel consideration of the potentiometric properties exhibited by humic and fulvic acids. The treatment is then extended to account for functional site heterogeneity. Sample results are presented for analysis of the ion-binding reactions of a standard soil fulvic acid (Armadale Horizons Bh) with this approach to test its capability for anticipation of metal ion removal from solution. The ultimate refined model is shown to be adaptable, after appropriate consideration of the heterogeneity and polyelectrolyte factors, to programming already available for the consideration of ion binding by inorganics in natural waters. (orig.)

  6. Naked eye sensor on polyvinyl chloride platform of chromo-ionophore molecular assemblies: A smart way for the colorimetric sensing of toxic metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakaran, Deivasigamani; Nanjo, Hiroshi [Research Centre for Compact Chemical Process, National Institute of Advanced Industrial Science and Technology (AIST), Tohoku, 4-2-1 Nigatake, Miyagino-Ku, Sendai 983 8551 (Japan); Matsunaga, Hideyuki [Research Centre for Compact Chemical Process, National Institute of Advanced Industrial Science and Technology (AIST), Tohoku, 4-2-1 Nigatake, Miyagino-Ku, Sendai 983 8551 (Japan)], E-mail: hide.matsunaga@aist.go.jp

    2007-10-03

    We demonstrate the possibility of fabricating a simple, naked eye colorimetric sensor miniature, using chromo-ionophore molecular assemblies anchored on polyvinyl chloride (PVC) surface. The ion-sensing probe (4-n-dodecyl-6-(2-thiazolylazo)-resorcinol) provides a better efficiency with PVC platform in developing a series of colour transitions, while targeting trace levels of Cd{sup 2+}, Pb{sup 2+} and Hg{sup 2+}. The physical properties of the film sensor are controlled by measuring the probe isotherm plot. The surface morphology and molecular composition of the solid-state optical sensor are characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The changes in sensor's optical intensity and its response time for the target analytes are followed by absorption spectroscopy. High speed of response (t {<=} 5 min) and confidence in determination of analytes from chemically complex matrices has been achieved, using simulated synthetic mixtures and spiked real environmental samples, with a relative standard deviation of <3.9%. The proposed method offers consistent data reproducibility and reliability, with a detection limit of 0.031, 0.025 and 0.034 {mu}M, for Cd{sup 2+}, Pb{sup 2+} and Hg{sup 2+} ions, respectively. The sensor strips are reversible and reusable without any change in the sensing efficiency, up to four cycles. The signal response observed with the proposed method is consistent between sensors, and also are stable over time.

  7. An ion-exchange nanomembrane sensor for detection of nucleic acids using a surface charge inversion phenomenon.

    Science.gov (United States)

    Senapati, Satyajyoti; Slouka, Zdenek; Shah, Sunny S; Behura, Susanta K; Shi, Zonggao; Stack, M Sharon; Severson, David W; Chang, Hsueh-Chia

    2014-10-15

    We present a novel low-cost biosensor for rapid, sensitive and selective detection of nucleic acids based on an ionic diode feature of an anion exchange nanoporous membrane under DC bias. The ionic diode feature is associated with external surface charge inversion on the positively charged anion exchange nanomembrane upon hybridization of negatively charged nucleic acid molecules to single-stranded oligoprobes functionalized on the membrane surface resulting in the formation of a cation selective monolayer. The resulting bipolar membrane causes a transition from electroconvection-controlled to water-splitting controlled ion conductance, with a large ion current signature that can be used to accurately quantify the hybridized nucleic acids. The platform is capable of distinguishing two base-pair mismatches in a 22-base pairing segment of microRNAs associated with oral cancer, as well as serotype-specific detection of dengue virus. We also show the sensor' capability to selectively capture target nucleic acids from a heterogeneous mixture. The limit of detection is 1 pM for short 27 base target molecules in a 15-min assay. Similar hybridization results are shown for short DNA molecules as well as RNAs from Brucella and Escherichia coli. The versatility and simplicity of this low-cost biosensor should enable point-of-care diagnostics in food, medical and environmental safety markets.

  8. Studies on rapid ion-exchange separation of the transplutonium elements with mineral acid-methanol mixed media

    International Nuclear Information System (INIS)

    In order to study properties of short-lived transplutonium nuclides synthesized by heavy-ion bombardment, three methods for rapid separation of tri-valent transplutonium elements by ion-exchange chromatography with mineral acid-methanol mixed media at elevated temperature were investigated. The first separation method was anion-exchange chromatography with nitric acid-methanol mixed media. The second method was anion-exchange choromatography with dilute hydrochloric acid-methanol mixed media. The third method was improved cation-exchange chromatography with single-column operation using the mixed media of hydrochloric acid and methanol. The separation methods developed were found applicable to studies on synthesis of the trans-plutonium nuclides, 250Fm (T1/2:30 min), 244,245,246Cf (T1/2:20 min, 46 min and 35.7 h, respectively) from the 16O + 238U and12C + 242Pu reactions, and on the decay property of 245Cf. Attempts to search for new actinide nuclides, such as 240U and neutron deficient nuclides of Am, Cm and Bk, were made by a quick purification. The separation system was also applied to the rapid and effective separation of Nd, Am and Cm from spent nuclear fuel samples, for burn-up determination. (J.P.N.) 242 refs

  9. Surface doping of La ions into ZnO nanocrystals to lower the optimal working temperature for HCHO sensing properties.

    Science.gov (United States)

    Tian, Shouqin; Zhang, Yupeng; Zeng, Dawen; Wang, Hao; Li, Neng; Xie, Changsheng; Pan, Chunxu; Zhao, Xiujian

    2015-11-01

    Lowering the working temperature without sacrificing other good gas-sensing properties is of particular interest to gas sensors for an excellent performance. In this work, La surface doped ZnO nanocrystals were successfully prepared by a facile thermal treatment with lanthanum nitrate (La(NO3)3) solution injected into ZnO thick films, which exhibited a remarkable decrease in the optimal working temperature for formaldehyde (HCHO) sensing properties. This was probably attributed to the formation of surface LaZn defects in the ZnO nanocrystals which was evidenced by XRD, XPS results and DFT calculations. The surface LaZn defects can introduce a shallower donor level than oxygen vacancies, and probably facilitate the charge transfer from oxygen species to ZnO for producing chemisorbed oxygen species more easily. This was in good agreement with the DFT results that the absorption energy of oxygen molecules on the surface of La doped ZnO was only -10.61 eV, much lower than that of pure ZnO. Moreover, the optimal working temperature of the La doped ZnO based sensor was significantly decreased from 350 to 250 °C without sacrificing the high and quick response to HCHO gas as the content of surface LaZn defects was increased gradually. Therefore, the behavior of the surface LaZn defects in the optimal working temperature revealed a HCHO response mechanism in ZnO, which can provide new insights into the enhanced HCHO sensing performance of gas sensors. PMID:26421631

  10. Cadmium Sulphide-Reduced Graphene Oxide-Modified Photoelectrode-Based Photoelectrochemical Sensing Platform for Copper(II) Ions

    Science.gov (United States)

    Ibrahim, I; Lim, H. N; Huang, N. M; Pandikumar, A

    2016-01-01

    A photoelectrochemical (PEC) sensor with excellent sensitivity and detection toward copper (II) ions (Cu2+) was developed using a cadmium sulphide-reduced graphene oxide (CdS-rGO) nanocomposite on an indium tin oxide (ITO) surface, with triethanolamine (TEA) used as the sacrificial electron donor. The CdS nanoparticles were initially synthesized via the aerosol-assisted chemical vapor deposition (AACVD) method using cadmium acetate and thiourea as the precursors to Cd2+ and S2-, respectively. Graphene oxide (GO) was then dip-coated onto the CdS electrode and sintered under an argon gas flow (50 mL/min) for the reduction process. The nanostructured CdS was adhered securely to the ITO by a continuous network of rGO that also acted as an avenue to intensify the transfer of electrons from the conduction band of CdS. The photoelectrochemical results indicated that the ITO/CdS-rGO photoelectrode could facilitate broad UV-visible light absorption, which would lead to a higher and steady-state photocurrent response in the presence of TEA in 0.1 M KCl. The photocurrent decreased with an increase in the concentration of Cu2+ ions. The photoelectrode response for Cu2+ ion detection had a linear range of 0.5–120 μM, with a limit of detection (LoD) of 16 nM. The proposed PEC sensor displayed ultra-sensitivity and good selectivity toward Cu2+ ion detection. PMID:27176635

  11. Cadmium Sulphide-Reduced Graphene Oxide-Modified Photoelectrode-Based Photoelectrochemical Sensing Platform for Copper(II) Ions.

    Science.gov (United States)

    Ibrahim, I; Lim, H N; Huang, N M; Pandikumar, A

    2016-01-01

    A photoelectrochemical (PEC) sensor with excellent sensitivity and detection toward copper (II) ions (Cu2+) was developed using a cadmium sulphide-reduced graphene oxide (CdS-rGO) nanocomposite on an indium tin oxide (ITO) surface, with triethanolamine (TEA) used as the sacrificial electron donor. The CdS nanoparticles were initially synthesized via the aerosol-assisted chemical vapor deposition (AACVD) method using cadmium acetate and thiourea as the precursors to Cd2+ and S2-, respectively. Graphene oxide (GO) was then dip-coated onto the CdS electrode and sintered under an argon gas flow (50 mL/min) for the reduction process. The nanostructured CdS was adhered securely to the ITO by a continuous network of rGO that also acted as an avenue to intensify the transfer of electrons from the conduction band of CdS. The photoelectrochemical results indicated that the ITO/CdS-rGO photoelectrode could facilitate broad UV-visible light absorption, which would lead to a higher and steady-state photocurrent response in the presence of TEA in 0.1 M KCl. The photocurrent decreased with an increase in the concentration of Cu2+ ions. The photoelectrode response for Cu2+ ion detection had a linear range of 0.5-120 μM, with a limit of detection (LoD) of 16 nM. The proposed PEC sensor displayed ultra-sensitivity and good selectivity toward Cu2+ ion detection. PMID:27176635

  12. Cadmium Sulphide-Reduced Graphene Oxide-Modified Photoelectrode-Based Photoelectrochemical Sensing Platform for Copper(II) Ions

    OpenAIRE

    Ibrahim, I.; Lim, H. N; N. M. Huang; Pandikumar, A

    2016-01-01

    A photoelectrochemical (PEC) sensor with excellent sensitivity and detection toward copper (II) ions (Cu2+) was developed using a cadmium sulphide-reduced graphene oxide (CdS-rGO) nanocomposite on an indium tin oxide (ITO) surface, with triethanolamine (TEA) used as the sacrificial electron donor. The CdS nanoparticles were initially synthesized via the aerosol-assisted chemical vapor deposition (AACVD) method using cadmium acetate and thiourea as the precursors to Cd2+ and S2-, respectively....

  13. Cadmium Sulphide-Reduced Graphene Oxide-Modified Photoelectrode-Based Photoelectrochemical Sensing Platform for Copper(II Ions.

    Directory of Open Access Journals (Sweden)

    I Ibrahim

    Full Text Available A photoelectrochemical (PEC sensor with excellent sensitivity and detection toward copper (II ions (Cu2+ was developed using a cadmium sulphide-reduced graphene oxide (CdS-rGO nanocomposite on an indium tin oxide (ITO surface, with triethanolamine (TEA used as the sacrificial electron donor. The CdS nanoparticles were initially synthesized via the aerosol-assisted chemical vapor deposition (AACVD method using cadmium acetate and thiourea as the precursors to Cd2+ and S2-, respectively. Graphene oxide (GO was then dip-coated onto the CdS electrode and sintered under an argon gas flow (50 mL/min for the reduction process. The nanostructured CdS was adhered securely to the ITO by a continuous network of rGO that also acted as an avenue to intensify the transfer of electrons from the conduction band of CdS. The photoelectrochemical results indicated that the ITO/CdS-rGO photoelectrode could facilitate broad UV-visible light absorption, which would lead to a higher and steady-state photocurrent response in the presence of TEA in 0.1 M KCl. The photocurrent decreased with an increase in the concentration of Cu2+ ions. The photoelectrode response for Cu2+ ion detection had a linear range of 0.5-120 μM, with a limit of detection (LoD of 16 nM. The proposed PEC sensor displayed ultra-sensitivity and good selectivity toward Cu2+ ion detection.

  14. Large area graphene ion sensitive field effect transistors with tantalum pentoxide sensing layers for pH measurement at the Nernstian limit

    Energy Technology Data Exchange (ETDEWEB)

    Fakih, Ibrahim, E-mail: ibrahim.fakih@mail.mcgill.ca; Sabri, Shadi; Szkopek, Thomas, E-mail: thomas.szkopek@mcgill.ca [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada); Mahvash, Farzaneh [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada); Département de Chimie et Biochimie, Universite du Québec à Montréal, Montreal, Quebec H3C 3P8 (Canada); Nannini, Matthieu [McGill Nanotools Microfab, McGill University, Montreal, Quebec H3A 2A7 (Canada); Siaj, Mohamed [Département de Chimie et Biochimie, Universite du Québec à Montréal, Montreal, Quebec H3C 3P8 (Canada)

    2014-08-25

    We have fabricated and characterized large area graphene ion sensitive field effect transistors (ISFETs) with tantalum pentoxide sensing layers and demonstrated pH sensitivities approaching the Nernstian limit. Low temperature atomic layer deposition was used to deposit tantalum pentoxide atop large area graphene ISFETs. The charge neutrality point of graphene, inferred from quantum capacitance or channel conductance, was used to monitor surface potential in the presence of an electrolyte with varying pH. Bare graphene ISFETs exhibit negligible response, while graphene ISFETs with tantalum pentoxide sensing layers show increased sensitivity reaching up to 55 mV/pH over pH 3 through pH 8. Applying the Bergveld model, which accounts for site binding and a Guoy-Chapman-Stern picture of the surface-electrolyte interface, the increased pH sensitivity can be attributed to an increased buffer capacity reaching up to 10{sup 14} sites/cm{sup 2}. ISFET response was found to be stable to better than 0.05 pH units over the course of two weeks.

  15. Thioglycolic acid-capped CuInS{sub 2}/ZnS quantum dots as fluorescent probe for cobalt ion detection

    Energy Technology Data Exchange (ETDEWEB)

    Zi, Lili; Huang, Yu [Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, 4 Tongjia Lane, Gulou District, Nanjing 210009 (China); Department of Analytical Chemistry, China Pharmaceutical University, 24 Tongjia Lane, Gulou District, Nanjing 210009 (China); Yan, Zhengyu, E-mail: yanzhengyujiang@126.com [Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, 4 Tongjia Lane, Gulou District, Nanjing 210009 (China); Department of Analytical Chemistry, China Pharmaceutical University, 24 Tongjia Lane, Gulou District, Nanjing 210009 (China); Liao, Shenghua, E-mail: liaoshenghuacpu@hotmail.com [Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, 4 Tongjia Lane, Gulou District, Nanjing 210009 (China); Department of Analytical Chemistry, China Pharmaceutical University, 24 Tongjia Lane, Gulou District, Nanjing 210009 (China)

    2014-04-15

    A novel sensing fluorescent probe based on the fluorescence quenching of the thioglycolic acid-capped CuInS{sub 2}/ZnS quantum dots (CuInS{sub 2}/ZnS/TGA QDs) was established for cobalt ions detection. The fluorescence quenching of CuInS{sub 2}/ZnS/TGA QDs was due to the increasing surface deficiency and the inner-filter effect, which were attributed to the reaction between Co{sup 2+} and sulfur bonds on the surface of QDs. The quenching curve could be fitted by a typical Stern–Volmer-type equation, with a linear relationship between the quenching efficiency and the concentration of cobalt ions in the range of 0.3012–90.36 μmol L{sup −1}. And the detection limit (S/N=3) for Co{sup 2+} was 0.16 μmol L{sup −1}. Therefore, the established probe provided a simple, rapid, cheap and sensitive method for Co{sup 2+} detection. In a word, this method can be used to detect Co{sup 2+} in the environment. -- Highlights: • The CuInS2/ZnS QDs were used for the first time as a fluorescent probe for Co{sup 2+} detection. • The dramatic color change could be observed when Co{sup 2+} was added into the QDs solution. • The quenching of QDs was due to the increasing surface deficiency and the inner-filter effect. • This rapid, cheap and sensitive method was applied to the detection of Co{sup 2+} in simulated water.

  16. Thioglycolic acid-capped CuInS2/ZnS quantum dots as fluorescent probe for cobalt ion detection

    International Nuclear Information System (INIS)

    A novel sensing fluorescent probe based on the fluorescence quenching of the thioglycolic acid-capped CuInS2/ZnS quantum dots (CuInS2/ZnS/TGA QDs) was established for cobalt ions detection. The fluorescence quenching of CuInS2/ZnS/TGA QDs was due to the increasing surface deficiency and the inner-filter effect, which were attributed to the reaction between Co2+ and sulfur bonds on the surface of QDs. The quenching curve could be fitted by a typical Stern–Volmer-type equation, with a linear relationship between the quenching efficiency and the concentration of cobalt ions in the range of 0.3012–90.36 μmol L−1. And the detection limit (S/N=3) for Co2+ was 0.16 μmol L−1. Therefore, the established probe provided a simple, rapid, cheap and sensitive method for Co2+ detection. In a word, this method can be used to detect Co2+ in the environment. -- Highlights: • The CuInS2/ZnS QDs were used for the first time as a fluorescent probe for Co2+ detection. • The dramatic color change could be observed when Co2+ was added into the QDs solution. • The quenching of QDs was due to the increasing surface deficiency and the inner-filter effect. • This rapid, cheap and sensitive method was applied to the detection of Co2+ in simulated water

  17. Temperature and acidity effects on WO{sub 3} nanostructures and gas-sensing properties of WO{sub 3} nanoplates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Huili [School of Chemistry and Chemical Engineering, Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, Tianjin University of Technology, Tianjin 300384 (China); Liu, Zhifang; Yang, Jiaqin; Guo, Wei [Department of Materials Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (MOE), TKL of Metal and Molecule-based Material Chemistry, Synergetic Innovation Centre of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University, Tianjin 300071 (China); Zhu, Lianjie, E-mail: zhulj@tjut.edu.cn [School of Chemistry and Chemical Engineering, Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, Tianjin University of Technology, Tianjin 300384 (China); Zheng, Wenjun, E-mail: zhwj@nankai.edu.cn [Department of Materials Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (MOE), TKL of Metal and Molecule-based Material Chemistry, Synergetic Innovation Centre of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University, Tianjin 300071 (China)

    2014-09-15

    Graphical abstract: Generally, large acid quantity and high temperature are beneficial to the formation of anhydrous WO3, but the acidity effect on the crystal phase is weaker than that of temperature. Large acid quantity is found helpful to the oriented growth of tungsten oxides, forming a nanoplate-like product. - Highlights: • Large acid quantity is propitious to the oriented growth of a WO{sub 3} nanoplate. • Effect of acid quantity on crystal phases of products is weaker than that of temperature. • One step hydrothermal synthesis of WO{sub 3} is facile and can be easily scaled up. • A WO{sub 3} nanoplate shows a fast response and distinct sensing selectivity to acetone gas. - Abstract: WO{sub 3} nanostructures were successfully synthesized by a facile hydrothermal method using Na{sub 2}WO{sub 4}·2H{sub 2}O and HNO{sub 3} as raw materials. They are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The specific surface area was obtained from N{sub 2} adsorption–desorption isotherm. The effects of the amount of HNO{sub 3}, hydrothermal temperature and reaction time on the crystal phases and morphologies of the WO{sub 3} nanostructures were investigated in detail, and the reaction mechanism was discussed. Large amount of acid is found for the first time to be helpful to the oriented growth of tungsten oxides, forming nanoplate-like products, while hydrothermal temperature has more influence on the crystal phase of the product. Gas-sensing properties of the series of as-prepared WO{sub 3} nanoplates were tested by means of acetone, ethanol, formaldehyde and ammonia. One of the WO{sub 3} nanoplates with high specific surface area and high crystallinity displays high sensitivity, fast response and distinct sensing selectivity to acetone gas.

  18. Ion-Exclusion High-Performance Liquid Chromatography of Aliphatic Organic Acids Using a Surfactant-Modified C18 Column.

    Science.gov (United States)

    Fasciano, Jennifer M; Mansour, Fotouh R; Danielson, Neil D

    2016-07-01

    Ion exclusion chromatography (IELC) of short chain aliphatic carboxylic acids is normally done using a cation exchange column under standard HPLC conditions but not in the ultra-HPLC (UHPLC) mode. A novel IELC method for the separation of this class of carboxylic acids by either HPLC or UHPLC utilizing a C18 column dynamically modified with sodium dodecyl sulfate has been developed. The sample capacity is estimated to be near 10 mM for a 20 µL injection or 0.2 µmol using a 150 × 4.6 mm column. The optimum mobile phase determined for three standard mixtures of organic acids is 1.84 mM sulfuric acid at pH 2.43 and a flow rate of 0.6 mL/min. Under optimized conditions, a HPLC separation of four aliphatic carboxylic acids such as tartaric, malonic, lactic and acetic can be achieved in under 4 min and in column as measured by the retention order of maleic and fumaric acid is estimated to be ∼4,000 column volumes using HPLC and 600 by UHPLC. Reproducible chromatograms are achieved over at least a 2-month period. This study shows that the utility of a C18 column can be easily extended when needed to IELC under either standard or UHPLC conditions.

  19. Development of a method for calculating the equilibrium and kinetics of ion exchange on a weak acid resin in a ternary system H+-Ca2+-Mg2+

    International Nuclear Information System (INIS)

    In technical applications ion exchange resins are applied in filters. The breakthrough behaviour of such filters can be calculated using mathematical relationships for equilibrium and kinetics. An according method has been developed for a ternary ion exchage problem on a weak acid resin. Theoretical results are verified by means of experimental data. (orig.)

  20. CaMac1, a Candida albicans Copper Ion-sensing Transcription Factor, Pro- motes Filamentous and Invasive Growth in Saccharomyces cerevisiae

    Institute of Scientific and Technical Information of China (English)

    Guang-Hua HUANG; Xin-Yi NIE; Jiang-Ye CHEN

    2006-01-01

    Molecular mechanisms of morphogenesis share many common components between Candida albicans and Saccharomyces cerevisiae. The Kssl-associated MAPK cascade and the cAMP/PKA pathway are two important signal transduction pathways that control morphogenesis in S. cerevisiae. A C. albicans copper ion-sensing transcription factor gene, CaMAC1, was cloned from C. albicans SC5314. Ectopic expression of CaMAC1 in S. cerevisiae promoted filamentous and invasive growth. In diploid cells, CaMacl could suppress the filamentous growth defect of mutants in the Kss 1-associated MAPK pathway and the cAMP/PKA pathway. In haploid strains, ectopic expression of CaMAC1 suppressed the invasive growth defect of mutants in the MAPK pathway (ste7, stel2 and tecl), but failed to suppress the invasive growth defect of thefio8 mutant. Our results suggest that the activation of CaMacl is independent of the MAPK and cAMP/PKA pathways in filament formation, but requires Flo8 factor for invasive growth. In the media containing a high concentration of CuSO4, the yeast filamentous and invasive growth was blocked. The activating effect of CaMacl is inhibited by copper ions.

  1. Extraction of Lanthanide and Actinide Ions from Aqueous Mixtures Using a Carboxylic Acid-Functionalized Porous Aromatic Framework.

    Science.gov (United States)

    Demir, Selvan; Brune, Nicholas K; Van Humbeck, Jeffrey F; Mason, Jarad A; Plakhova, Tatiana V; Wang, Shuao; Tian, Guoxin; Minasian, Stefan G; Tyliszczak, Tolek; Yaita, Tsuyoshi; Kobayashi, Tohru; Kalmykov, Stepan N; Shiwaku, Hideaki; Shuh, David K; Long, Jeffrey R

    2016-04-27

    Porous aromatic frameworks (PAFs) incorporating a high concentration of acid functional groups possess characteristics that are promising for use in separating lanthanide and actinide metal ions, as required in the treatment of radioactive waste. These materials have been shown to be indefinitely stable to concentrated acids and bases, potentially allowing for multiple adsorption/stripping cycles. Additionally, the PAFs combine exceptional features from MOFs and inorganic/activated carbons giving rise to tunable pore surfaces and maximum chemical stability. Herein, we present a study of the adsorption of selected metal ions, Sr(2+), Fe(3+), Nd(3+), and Am(3+), from aqueous solutions employing a carbon-based porous aromatic framework, BPP-7 (Berkeley Porous Polymer-7). This material displays high metal loading capacities together with excellent adsorption selectivity for neodymium over strontium based on Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. Based in part upon X-ray absorption spectroscopy studies, the stronger adsorption of neodymium is attributed to multiple metal ion and binding site interactions resulting from the densely functionalized and highly interpenetrated structure of BPP-7. Recyclability and combustibility experiments demonstrate that multiple adsorption/stripping cycles can be completed with minimal degradation of the polymer adsorption capacity. PMID:27163056

  2. Direct Formation of Oxocarbenium Ions under Weakly Acidic Conditions: Catalytic Enantioselective Oxa-Pictet-Spengler Reactions.

    Science.gov (United States)

    Zhao, Chenfei; Chen, Shawn B; Seidel, Daniel

    2016-07-27

    Two catalysts, an amine HCl salt and a bisthiourea, work in concert to enable the generation of oxocarbenium ions under mild conditions. The amine catalyst generates an iminium ion of sufficient electrophilicity to enable 1,2-attack by an alcohol. Catalyst turnover is achieved by amine elimination with concomitant formation of an oxocarbenium intermediate. The bisthiourea catalyst accelerates all of the steps of the reaction and controls the stereoselectivity via anion binding/ion pair formation. This new concept was applied to direct catalytic enantioselective oxa-Pictet-Spengler reactions of tryptophol with aldehydes. PMID:27396413

  3. 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...... mutated C932 close to the proposed channel inlet. C932F reduced Na+ affinity ~73-fold. This fits into a model, where the bulky phenylalanine prevents Na+ from entering the channel....

  4. Voltammetric characterization of Hg2+ ion behaviour in acid media on different electrodes

    Directory of Open Access Journals (Sweden)

    Nemtoi Gh.

    2014-12-01

    Full Text Available This article presents some aspects related to the cathodic discharge of the mercuric ion provided from HgCl2 into an aqueous solution of 0.1 M H2SO4 on different types of electrodes: gold disc electrode (GDE, carbon paste electrode (CPE and platinum-disk electrode (PDE. Using the rotating disk electrode technique applied on PDE it was established that the cathodic discharge mechanism for the mercuric ion is based on both process types: mass transport, achieved by diffusion and charge transfer, achieved by electron transfer from cathode to mercury ion

  5. Multivariate analyses of salt stress and metabolite sensing in auto- and heterotroph Chenopodium cell suspensions.

    Science.gov (United States)

    Wongchai, C; Chaidee, A; Pfeiffer, W

    2012-01-01

    Global warming increases plant salt stress via evaporation after irrigation, but how plant cells sense salt stress remains unknown. Here, we searched for correlation-based targets of salt stress sensing in Chenopodium rubrum cell suspension cultures. We proposed a linkage between the sensing of salt stress and the sensing of distinct metabolites. Consequently, we analysed various extracellular pH signals in autotroph and heterotroph cell suspensions. Our search included signals after 52 treatments: salt and osmotic stress, ion channel inhibitors (amiloride, quinidine), salt-sensing modulators (proline), amino acids, carboxylic acids and regulators (salicylic acid, 2,4-dichlorphenoxyacetic acid). Multivariate analyses revealed hirarchical clusters of signals and five principal components of extracellular proton flux. The principal component correlated with salt stress was an antagonism of γ-aminobutyric and salicylic acid, confirming involvement of acid-sensing ion channels (ASICs) in salt stress sensing. Proline, short non-substituted mono-carboxylic acids (C2-C6), lactic acid and amiloride characterised the four uncorrelated principal components of proton flux. The proline-associated principal component included an antagonism of 2,4-dichlorphenoxyacetic acid and a set of amino acids (hydrophobic, polar, acidic, basic). The five principal components captured 100% of variance of extracellular proton flux. Thus, a bias-free, functional high-throughput screening was established to extract new clusters of response elements and potential signalling pathways, and to serve as a core for quantitative meta-analysis in plant biology. The eigenvectors reorient research, associating proline with development instead of salt stress, and the proof of existence of multiple components of proton flux can help to resolve controversy about the acid growth theory. PMID:21974771

  6. Direct determination of trace amounts of acetic acid using a novel ambient glow discharge ion source

    Institute of Scientific and Technical Information of China (English)

    Xiao Hao Wang; Kun Liu; Fei Tang; Jiu Ming He; Xue Ye Wei; Zeper Abliz

    2010-01-01

    A novel ambient glow discharge ion source with improved line-cylinder electrodes is put forward and designed in this paper.The diameters of inner and outer electrodes are 0.16 and 4 mm respectively.With a special assembly method,a perfect coaxiality of the two electrodes is obtained.From the gas discharge experiment,it can be seen that the discharge can stably work in normal glow discharge mode.The operating currents of the ion source are in an order of milliamperes and can generate a much larger number and wider variety of reagent ions.The MS experiment shows that the ion source has higher detection sensitivity.

  7. Lanthanide-Potassium Biphenyl-3,3'-disulfonyl-4,4'-dicarboxylate Frameworks: Gas Sorption, Proton Conductivity, and Luminescent Sensing of Metal Ions.

    Science.gov (United States)

    Zhou, Li-Juan; Deng, Wei-Hua; Wang, Yu-Ling; Xu, Gang; Yin, Shun-Gao; Liu, Qing-Yan

    2016-06-20

    A novel sulfonate-carboxylate ligand of biphenyl-3,3'-disulfonyl-4,4'-dicarboxylic acid (H4-BPDSDC) and its lanthanide-organic frameworks {[LnK(BPDSDC)(DMF)(H2O)]·x(solvent)}n (JXNU-2, where JXNU denotes Jiangxi Normal University, DMF indicates dimethylformamide, and Ln = Sm(3+), Eu(3+), and Pr(3+)) were synthesized and structurally characterized. The three isomorphous lanthanide compounds feature three-dimensional frameworks constructed from one-dimensional (1D) rod-shaped heterometallic Ln-K secondary building units and are an illustration of a Kagome-like lattice with large 1D hexagonal channels and small 1D trigonal channels. The porous material of the representive JXNU-2(Sm) has an affinity to quadrupolar molecules such as CO2 and C2H2. In addition, the JXNU-2(Sm) compound exhibits humidity- and temperature-dependent proton conductivity with a large value of 1.11 × 10(-3) S cm(-1) at 80 °C and 98% relative humidity. The hydrophilic sulfonate group on the surface of channels facilitates enrichment of the solvate water molecules in the channels, which enhances the proton conductivity of this material. Moreover, the JXNU-2(Eu) material with the characteristic bright red color shows the potential for recognition of K(+) and Fe(3+) ions. The enhancing Eu(3+) luminescence with the K(+) ion and quenching Eu(3+) luminescence with the Fe(3+) ion can be associated with the functional groups of the organic ligand.

  8. Selective recovery of Pd(II) from extremely acidic solution using ion-imprinted chitosan fiber: Adsorption performance and mechanisms.

    Science.gov (United States)

    Lin, Shuo; Wei, Wei; Wu, Xiaohui; Zhou, Tao; Mao, Juan; Yun, Yeoung-Sang

    2015-12-15

    A novel, selective and acid-resisting chitosan fiber adsorbent was prepared by the ion-imprinting technique using Pd(II) and epichlorohydrin as the template and two-step crosslinking agent, respectively. The resulting ion-imprinted chitosan fibers (IIF) were used to selectively adsorb Pd(II) under extremely acidic synthetic metal solutions. The adsorption and selectivity performances of IIF including kinetics, isotherms, pH effects, and regeneration were investigated. Pd(II) rapidly adsorbed on the IIF within 100 min, achieving the adsorption equilibrium. The isotherm results showed that the maximum Pd(II) uptake on the IIF was maintained as 324.6-326.4 mg g(-1) in solutions containing single and multiple metals, whereas the Pd(II) uptake on non-imprinted fibers (NIF) decreased from 313.7 to 235.3 mg g(-1) in solution containing multiple metals. Higher selectivity coefficients values were obtained from the adsorption on the IIF, indicating a better Pd(II) selectivity. The amine group, supposedly the predominant adsorption site for Pd(II), was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The pH value played a significant role on the mechanism of the selective adsorption in the extremely acidic conditions. Furthermore, the stabilized performance for three cycles of sorption/desorption shows a potential for further large-scale applications. PMID:26073516

  9. New Insight into Metal Ion-Driven Catalysis of Nucleic Acids by Influenza PA-Nter

    Science.gov (United States)

    Kotlarek, Daria; Worch, Remigiusz

    2016-01-01

    PA subunit of influenza RNA-dependent RNA polymerase deserves constantly increasing attention due to its essential role in influenza life cycle. N-terminal domain of PA (PA-Nter) harbors endonuclease activity, which is indispensable in viral transcription and replication. Interestingly, existing literature reports on in vitro ion preferences of the enzyme are contradictory. Some show PA-Nter activity exclusively with Mn2+, whereas others report Mg2+ as a natural cofactor. To clarify it, we performed a series of experiments with varied ion concentrations and substrate type. We observed cleavage in the presence of both ions, with a slight preference for manganese, however PA-Nter activity highly depended on the amount of residual, co-purified ions. Furthermore, to quantify cleavage reaction rate, we applied fluorescence cross-correlation spectroscopy (FCCS), providing highly sensitive and real-time monitoring of single molecules. Using nanomolar ssDNA in the regime of enzyme excess, we estimated the maximum reaction rate at 0.81± 0.38 and 1.38± 0.34 nM/min for Mg2+ and Mn2+, respectively. However, our calculations of PA-Nter ion occupancy, based on thermodynamic data, suggest Mg2+ to be a canonical metal in PA-Nter processing of RNA in vivo. Presented studies constitute a step toward better understanding of PA-Nter ion-dependent activity, which will possibly contribute to new successful inhibitor design in the future. PMID:27300442

  10. UV-Vis Spectroscopy Study on Interaction between Microperoxidase-11 and Pr Ion Under Acid Rain Stress

    Institute of Scientific and Technical Information of China (English)

    吉红念; 黄晓华; 周青; 陆天虹

    2002-01-01

    Interaction between rare earth ion praseodymium (Pr(Ⅲ)) and MP11 with/without hydrogen ion (H+) in different media( aqueous, phosphate buffer, physiological condition) were studied by UV-Vis spectroscopy. All the results indicate that Pr(Ⅲ) interacts with MP11, increasing the non-planarity of porphyrin periphery, leading MP11 to form two conformations when titrated by Pr(Ⅲ). Excessive Pr(Ⅲ) acts as a contaminant in living organism. H+ and Pr(Ⅲ) have antagonistic effect on MP11, suggesting that at suitable concentration under physiological conditions, Pr(Ⅲ) can be used as biomodulator in protecting plants from acid rain stress or in rehabilitating the harm.

  11. Dicarboxylic acids, ω-oxocarboxylic acids, α-dicarbonyls, WSOC, OC, EC, and inorganic ions in wintertime size-segregated aerosols from central India: Sources and formation processes.

    Science.gov (United States)

    Deshmukh, Dhananjay K; Kawamura, Kimitaka; Deb, Manas K

    2016-10-01

    The size distributions of aerosols can provide evidences for their sources and formation processes in the atmosphere. Size-segregated aerosols (9-sizes) were collected in urban site (Raipur: 21.2°N and 82.3°E) in central India during winter of 2012-2013. The samples were analyzed for dicarboxylic acids (C2-C12), ω-oxocarboxylic acids (ωC2-ωC9), pyruvic acid and α-dicarbonyls (C2-C3) as well as elemental carbon (EC), organic carbon (OC), water-soluble OC (WSOC) and inorganic ions. Diacids showed a predominance of oxalic acid (C2) followed by succinic and azelaic acid whereas ω-oxoacids exhibited a predominance of glyoxylic acid and glyoxal was more abundant than methylglyoxal in all the sizes. Diacids, ω-oxoacids and α-dicarbonyls showed bimodal size distribution with peaks in fine and coarse modes. High correlations of fine mode diacids and related compounds with potassium and levoglucosan suggest that they were presumably due to a substantial contribution of primary emission from biomass burning and secondary production from biomass burning derived precursors. High correlations of C2 with higher carbon number diacids (C3-C9) suggest that they have similar sources and C2 may be produced via the decay of its higher homologous diacids in fine mode. Considerable portions of diacids and related compounds in coarse mode suggest that they were associated with mineral dust particles by their adsorption and photooxidation of anthropogenic and biogenic precursors via heterogeneous reaction on dust surface. This study demonstrates that biomass burning and dust particles are two major factors to control the size distribution of diacids and related compounds in the urban aerosols from central India. PMID:27414241

  12. Lanthanide ion exchange properties of a coordination polymer consisting of di(2-ethylhexyl) phosphoric acid and trivalent metal ions (Ce3+, Fe3+, or Al3+).

    Science.gov (United States)

    Ooi, Kenta; Tasaki-Handa, Yuiko; Abe, Yukie; Wakisaka, Akihiko

    2014-03-28

    Three kinds of coordination polymers ([M(dehp)3], M = Ce, Fe, or Al) were prepared by mixing the sodium form (Na(dehp)) of di(2-ethylhexyl) phosphoric acid and MCl3 in an ethanol-water binary mixture. They have monoclinic crystalline structure with similar lattice parameters. The lanthanide ion (Ln(3+) = La(3+), Sm(3+), Dy(3+), or Yb(3+)) exchange properties were studied in a 20 : 80 vol% ethanol-water binary mixture containing 2 mM Ln(NO3)3 at room temperature. The rate of Ln(3+) adsorption is relatively slow; it requires over 3 weeks to reach equilibrium. [M(dehp)3] has different Ln(3+) affinities depending on the kind of central metal ions: the affinity order at 3 week adsorption is Yb(3+) coordination preference and steric strain caused by the polymeric structure. The chemical and structural analyses suggested that the Ln(3+) adsorption progresses first by the central M(3+)/Ln(3+) exchange, followed by a morphological change to a rod-like or fibrous form by a solid phase reaction. In the case of [Fe(dehp)3], the eluted Fe(3+) may be hydrolyzed and precipitated as amorphous iron hydroxide.

  13. Succinic acid-based leaching system: A sustainable process for recovery of valuable metals from spent Li-ion batteries

    Science.gov (United States)

    Li, Li; Qu, Wenjie; Zhang, Xiaoxiao; Lu, Jun; Chen, Renjie; Wu, Feng; Amine, Khalil

    2015-05-01

    A hydrometallurgical method involving natural organic acid leaching has been developed for recovery of lithium and cobalt from the cathode active materials in spent lithium-ion batteries. Succinic acid is employed as leaching agent and H2O2 as reductant. The cobalt and lithium contents from the succinic acid-based treatment of spent batteries are determined by inductively coupled plasma-optical emission spectroscopy to calculate the leaching efficiency. The spent LiCoO2 samples after calcination and the residues after leaching are characterized by X-ray diffraction and scanning electron microscopy. The results show that nearly 100% of cobalt and more than 96% of lithium are leached under optimal conditions: succinic acid concentration of 1.5 mol L-1, H2O2 content of 4 vol.%, solid-to-liquid ratio of 15 g L-1, temperature of 70 °C, and reaction time of 40 min. Results are also given for fitting of the experimental data to acid leaching kinetic models.

  14. PimT, an amino acid exporter controls polyene production via secretion of the quorum sensing pimaricin-inducer PI-factor in Streptomyces natalensis

    Directory of Open Access Journals (Sweden)

    Guerra Susana M

    2009-06-01

    Full Text Available Abstract Background Polyenes represent a major class of antifungal agents characterised by the presence of a series of conjugated double bonds in their planar hydroxylated macrolide ring structure. Despite their general interest, very little is known about the factors that modulate their biosynthesis. Among these factors, we have recently discovered a new inducing compound (PI-factor in the pimaricin producer Streptomyces natalensis, which elicits polyene production in a manner characteristic of quorum sensing. Here, we describe the involvement of an amino-acid exporter from S. natalensis in modulating the expression of pimaricin biosynthetic genes via secretion of the quorum-sensing pimaricin-inducer PI-factor. Results Adjacent to the pimaricin gene cluster lies a member of the RhtB family of amino-acid exporters. Gene deletion and complementation experiments provided evidence for a role for PimT in the export of L-homoserine, L-serine, and L-homoserine lactone. Expression of the gene was shown to be induced by homoserine and by the quorum-sensing pimaricin-inducer PI-factor. Interestingly, the mutant displayed 65% loss of pimaricin production, and also 50% decrease in the production of PI, indicating that PimT is used as PI-factor exporter, and suggesting that the effect in antifungal production might be due to limited secretion of the inducer. Conclusion This report describes the involvement of an amino acid exporter (encoded by pimT in the vicinity of the pimaricin cluster in modulating the expression of antibiotic biosynthetic genes via secretion of the quorum-sensing pimaricin-inducer PI-factor. The discovery of the participation of amino acid exporters in a signal transduction cascade for the production of polyene macrolides is unexpected, and represents an important step forward towards understanding the regulatory network for polyene regulation. Additionally, this finding constitutes the first detailed characterization of an amino-acid

  15. Neomycin-loaded poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion exchange nanofibers for wound dressing materials.

    Science.gov (United States)

    Nitanan, Todsapon; Akkaramongkolporn, Prasert; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2013-05-01

    In this study, poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) blended with polyvinyl alcohol (PVA) was electrospun and then subjected to thermal crosslinking to produce PSSA-MA/PVA ion exchange nanofiber mats. The cationic drug neomycin (0.001, 0.01, and 0.1%, w/v) was loaded onto the cationic exchange fibers. The amount of neomycin loaded and released and the cytotoxicity of the fiber mats were analyzed. In vivo wound healing tests were also performed in Wistar rats. The results indicated that the diameters of the fibers were on the nanoscale (250 ± 21 nm). The ion exchange capacity (IEC) value and the percentage of water uptake were 2.19 ± 0.1 mequiv./g-dry fibers and 268 ± 15%, respectively. The loading capacity was increased upon increasing the neomycin concentration. An initial concentration of 0.1% (w/v) neomycin (F3) showed the highest loading capacity (65.7 mg/g-dry fibers). The neomycin-loaded nanofiber mats demonstrated satisfactory antibacterial activity against both Gram-positive and Gram-negative bacteria, and an in vivo wound healing test revealed that these mats performed better than gauze and blank nanofiber mats in decreasing acute wound size during the first week after tissue damage. In conclusion, the antibacterial neomycin-loaded PSSA-MA/PVA cationic exchange nanofiber mats have the potential for use as wound dressing materials.

  16. High-performance fluorescence sensing of lanthanum ions (La(3+)) by a polydentate pyridyl-based quinoxaline derivative.

    Science.gov (United States)

    Zhao, Qiang; Liu, Xiu-Ming; Li, Huan-Rong; Zhang, Ying-Hui; Bu, Xian-He

    2016-06-28

    A polydentate pyridyl derivative, 2,3,6,7,10,11-hexa(2-pyridyl)-dipyrazino [2,3-f:2',3'-h]quinoxaline (HPDQ), exhibits a high-performance fluorescence response to La(3+) with an ∼65 nm redshifted emission wavelength and 38 fold enhanced intensity, in contrast to its weakened emission for other lanthanide ions. The final La(3+) coordination complex in solution has a stoichiometric ratio of 1 : 3 of ligand-to-metal, as testified by the Job's plot and single crystal structure analyses. The red shift of the luminescence emission as well as UV-vis absorption was rationalized in terms of the change of the electron structure as indicated by nuclear magnetic titration, electrochemical experiment and density functional theoretical calculation, while the significant enhancement of emission was attributed to the enhanced π conjugated extent of HPDQ caused by La(3+) coordination.

  17. Luminescent properties of [UO{sub 2}(TFA){sub 2}(DMSO){sub 3}], a promising material for sensing and monitoring the uranyl ion

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Ramos, Pablo; Silva, Manuela Ramos; Silva, Pedro S. Pereira da [Centro de Fisica da Universidade de Coimbra (CFisUC), Department of Physics, Universidade de Coimbra (Portugal); Costa, Ana L.; Melo, J. Sergio Seixas de [Centro de Quimica de Coimbra, Department of Chemistry, Universidade de Coimbra (Portugal); Pereira, Laura C.J. [Centro de Ciencias e Tecnologias Nucleares, Instituto Superior Tecnico, Universidade de Lisboa, Bobadela LRS (Portugal); Martin-Gil, Jesus, E-mail: pmr@unizar.es [Advanced Materials Laboratory, Escuela Tecnica Superior de Ingenierias Agrarias, University of Valladolid, Palencia (Spain)

    2016-03-15

    An uranyl complex [UO{sub 2}(TFA){sub 2}(DMSO){sub 3}] (TFA=deprotonated trifluoroacetic acid; DMSO=dimethyl sulfoxide) has been successfully synthesized by reacting UO{sub 2}(CH{sub 3}COO){sub 2} ·H{sub 2} O with one equivalent of (CF{sub 3} CO){sub 2} O and DMSO. The complex has been characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis, FTIR spectroscopy, thermal analysis and absorption and emission spectroscopies. The spectroscopic properties of the material make it suitable for its application in the sensing and monitoring of uranyl in the PUREX process. (author)

  18. 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, lithi......, lithium iron phosphate (LFP) and lithium titanate oxide (LTO) were compared with lead acid batteries, in terms of their basics characteristics (e.g. capacity, internal resistance) and their dependence on the operating conditions....

  19. A study of gaseous benzenium and toluenium ions generated from 1,4- dihydro- and 1-methyl-1,4-dihydro-benzoic acids

    OpenAIRE

    Kuck, Dietmar; Schneider, Jens; Grützmacher, Hans-Friedrich

    1985-01-01

    Gaseous benzenium C6H7+(1) and toluenium C7H9+(2) ions have been generated by mass spectrometric loss of CO2H from the corresponding 1,4-dihydrobenzoic acids (3) and (4), and their fragmentations after ca. 10 µs have been investigated by means of mass-analysed ion kinetic energy (MIKE) spectrometry of some 2H and 13C labelled analogues. Metastable C6H7+ ions eliminate H2 after proton randomization, whereas metastable C7H9+ ions expel both H2 and CH4 after incomplete proton equilibration. In p...

  20. Dental erosion and sulfuric ion exposure levels in individuals working with sulfuric acid in lead storage battery manufacturing plant measured with mouth-rinse index.

    Science.gov (United States)

    Suyama, Yuji; Takaku, Satoru; Okawa, Yoshikazu; Matsukubo, Takashi

    2010-01-01

    To investigate dental erosion in employees working with sulfuric acid at a lead storage battery manufacturing plant and level of personal exposure to sulfuric ions, we measured sulfuric ion concentrations in the mouth rinse of those employees. We also measured exposure levels from air samples obtained from 2 employees from the same plant who did not work with sulfuric acid using a portable air sampler. At the same time, we collected and compared their mouth rinses with those from other employees. More specifically, we measured and compared sulfuric ion, calcium, and magnesium concentrations, along with pH levels from the mouth rinse of these two groups. Positive correlations were found between sulfuric ion and calcium concentrations (r=0.61, pacid could function as an indicator of sulfuric ion concentration in the work environment. Furthermore, this could lead to the development of a more accurate indicator of individual exposure.

  1. CYCLIC VOLTAMMETRY STUDIES OF COPPER (II) AND TELLURIUM (IV) IONS IN ACIDIC AQUEOUS SOLUTIONS FOR THIN FILM DEPOSITION

    OpenAIRE

    SARAVANAN NAGALINGAM; GEOK BEE TEH

    2014-01-01

    Cyclic voltammetry studies of copper (II) and tellurium (IV) ions in acidic aqueous solutions were carried out to determine the optimum condition for copper telluride thin film deposition. The voltammetry studies include reversible scans at different solution pH. Based on the voltammogram, suitable deposition conditions was determined to be in the range of -0.35 V to -0.45 V versus Ag/AgCl at pH values between 2.0 to 2.2 under non diffusion-limited conditions.

  2. CYCLIC VOLTAMMETRY STUDIES OF COPPER (II AND TELLURIUM (IV IONS IN ACIDIC AQUEOUS SOLUTIONS FOR THIN FILM DEPOSITION

    Directory of Open Access Journals (Sweden)

    SARAVANAN NAGALINGAM

    2014-05-01

    Full Text Available Cyclic voltammetry studies of copper (II and tellurium (IV ions in acidic aqueous solutions were carried out to determine the optimum condition for copper telluride thin film deposition. The voltammetry studies include reversible scans at different solution pH. Based on the voltammogram, suitable deposition conditions was determined to be in the range of -0.35 V to -0.45 V versus Ag/AgCl at pH values between 2.0 to 2.2 under non diffusion-limited conditions.

  3. Removal of Ni(II) and Cu(II) ions using native and acid treated Ni-hyperaccumulator plant Alyssum discolor from Turkish serpentine soil.

    Science.gov (United States)

    Bayramoglu, Gulay; Arica, M Yakup; Adiguzel, Nezaket

    2012-09-01

    Alyssum discolor biomass was collected from serpentine soil and was used for removal of metal ions. The plant species grown on serpentine soils are known to be rich with metals ions and thus have more capability for accumulating heavy metals. Native and acid-treated biomass of A. discolor (A. discolor) were utilized for the removal of Ni(II) and Cu(II) ions from aqueous solutions. The effects of contact time, initial concentration, and pH on the biosorption of Ni(II) and Cu(II) ions were investigated. Biosorption equilibrium was established in about 60 min. The surface properties of the biomass preparations were varied with pH, and the maximum amounts of Ni(II) and Cu(II) ions on both A. discolor biomass preparations were adsorbed at pH 5.0. The maximum biosorption capacities of the native, and acid-treated biomass preparations for Ni(II) were 13.1 and 34.7 mgg(-1) and for Cu(II) 6.15 and 17.8 mgg(-1) dry biomass, respectively. The biosorption of Ni(II) and Cu(II) ions from single and binary component systems can be successfully described by Langmuir and Freundlich isotherms. When the heavy metal ions were in competition, the amounts of biosorbed metal ions on the acid treated plant biomass were found to be 0.542 mmolg(-1) for Ni(II) and 0.162 mmolg(-1) for Cu(II), the A. discolor biomass was significantly selective for Ni(II) ions. The information gained from these studies was expected to indicate whether the native, and acid-treated forms can have the potential to be used for the removal and recovery of Ni(II) ions from wastewaters. PMID:22608134

  4. Effect of calcium ion on the adsorption of dissolved humic acid onto TiO2 particles in water

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to clarify the role of HA (humic acid)-TiO2 adsorption in the photocatalytic process, a series of experiments were performed to investigate the adsorption mechanisms in the absence or presence of calcium according to the intermolecular interaction force theory. Based on the experimental results, the models of adsorption mechanism were designed, which were useful in explaining the phenomena that happened during adsorption processes. The adsorption of humic acid onto the TiO2 particles was desperately pH-dependent; however, calcium could increase the amount of adsorption, which was mainly attributed to the calcium ion bridging. The effects of calcium concentration and TiO2 dosage on the adsorption process are also discussed.

  5. Total DNA of Glycyrrhiza uralensis transformed into Hansenula anomala by ion implantation:Preparing Glycyrrhizic acid in recombined yeasts

    International Nuclear Information System (INIS)

    Glycyrrhizic acid (GA) in Glycyrrhiza uralensis (G. uralensis) is physiologically active. In this study, the total DNA of wild G. uralensis was randomly transformed into Hansenula anomaly by implantation of low-energy Ar+ and N+, to produce five recombinant yeast strains relating to biological synthesis of the GA or Glycyrrhetinic acid (GAs). After culturing in liquid medium for 96 h, the resultant GA, 18α-GAs and 18β-Gas were determined by reversed-phase high performance liquid chromatography (RP-HPLC), and the corresponding concentrations were 114.49, 0.56, and 0.81 mg·L-1. After one hundred primers were analyzed with random amplified polymorphic DNA (RAPD), the seven different DNA fragments were produced by the N7059 strain of recombined yeasts, and, the polymerase chain reaction (PCR) verified that one of them came from the genome of G. uralensis, indicating a successful transfer of genetic information by ion implantation. (authors)

  6. Kinetic Approach to the Mechanism of Redox Reaction of Pyrocatechol Violet and Nitrite Ion in Aqueous Hydrochloric Acid

    Directory of Open Access Journals (Sweden)

    A. Adetoro

    2011-10-01

    Full Text Available The kinetics of the oxidation of Pyrocatechol violet (PCVH by nitrite ion (NO2- in aqueous acidic medium has been studied at 24±1ºC, I = 0.50 mol/dm3(NaCl, [H+] = 1.0×10-3 mol/dm3. The reaction is first order to [PCVH] and half order to [NO2-]. The redox reaction displayed a 1:1 stoichiometry and obeys the rate law: d[PCVH]/dt = (a + b[H+] [PCVH][NO2-]½. The second-order rate constant increases with increase in acid concentration and ionic strength. This system displayed positive salt effect while spectroscopic investigation and Michaelis-Menten plot showed evidence of intermediate complex formation in the course of the reaction. A plausible mechanism has been proposed for the reaction.

  7. Concentration of zinc ions in perchlorate medium by a menbrane-gel using an acid extractant (DEHPA

    Directory of Open Access Journals (Sweden)

    Belhadji L.

    2013-07-01

    Full Text Available Recent decades, it is an awareness of the importance of ecological balance in the environment, balances threatened by industrial pollution. A new spirit presides we seek to minimize pollution of receiving waters. The present work is to study the liquid-gel-extraction of zinc ions in perchlorate medium by an acid extractant: the di (ethyl-2 hexyl phosphorique acid, or DEHPA. Two types of polymers were used as supports of solvent extraction: a polybutadiene rubber cross-linked respectively with 0.1% dicumyl peroxide and 0.4% dicumyl peroxide, vulcanized at 160°C, one is most cross-linked than the other. The liquid-gel extraction is based on the principles of the liquid-liquid extraction.

  8. The influence of ion implantation on the corrosion behaviour of iron in acid solution

    International Nuclear Information System (INIS)

    The influence of ion implantation on the aqueous corrosion of pure iron in 1N H2SO4 was studied. The iron was bombarded with 5 x 1015 to 1017 ions.cm-2 of Ne, Ar, Cu, Pb and Au. The current density-potential curves of the implanted samples were measured and compared with that of untreated pure iron. Ne+ and Cu+ bombardments lead to a slightly higher corrosion rate in comparison with untreated iron. Pb+ depressed the corrosion rate by orders of magnitude. Au+ enhanced it by a factor of more than ten. The effect is attributed to a reduction or an increase of the activity of the electrode surface with respect to the cathodic hydrogen evolution reaction, i.e. the ion implantation influences strongly the exchange current density of the hydrogen evolution reaction. A marked influence of the implantation on the anodic behaviour of the corroding metal could also be observed. (author)

  9. Characterization of duodenal expression and localization of fatty acid-sensing receptors in humans: relationships with body mass index.

    Science.gov (United States)

    Little, Tanya J; Isaacs, Nicole J; Young, Richard L; Ott, Raffael; Nguyen, Nam Q; Rayner, Christopher K; Horowitz, Michael; Feinle-Bisset, Christine

    2014-11-15

    Fatty acids (FAs) stimulate the secretion of gastrointestinal hormones, including cholecystokinin (CCK) and glucagon like peptide-1 (GLP-1), which suppress energy intake. In obesity, gastrointestinal responses to FAs are attenuated. Recent studies have identified a key role for the FA-sensing receptors cluster of differentiation (CD)36, G protein-coupled receptor (GPR)40, GPR120, and GPR119 in mediating gastrointestinal hormone secretion. This study aimed to determine the expression and localization of these receptors in the duodenum of humans and to examine relationships with obesity. Duodenal mucosal biopsies were collected from nine lean [body mass index (BMI): 22 ± 1 kg/m2], six overweight (BMI: 28 ± 1 kg/m2), and seven obese (BMI: 49 ± 5 kg/m2) participants. Absolute levels of receptor transcripts were quantified using RT-PCR, while immunohistochemistry was used for localization. Transcripts were expressed in the duodenum of lean, overweight, and obese individuals with abundance of CD36>GPR40>GPR120>GPR119. Expression levels of GPR120 (r = 0.46, P = 0.03) and CD36 (r = 0.69, P = 0.0004) were directly correlated with BMI. There was an inverse correlation between expression of GPR119 with BMI (r2 = 0.26, P = 0.016). Immunolabeling studies localized CD36 to the brush border membrane of the duodenal mucosa and GPR40, GPR120, and GPR119 to enteroendocrine cells. The number of cells immunolabeled with CCK (r = -0.54, P = 0.03) and GLP-1 (r = -0.49, P = 0.045) was inversely correlated with BMI, such that duodenal CCK and GLP-1 cell density decreased with increasing BMI. In conclusion, CD36, GPR40, GPR120, and GPR119 are expressed in the human duodenum. Transcript levels of duodenal FA receptors and enteroendocrine cell density are altered with increasing BMI, suggesting that these changes may underlie decreased gastrointestinal hormone responses to fat and impaired energy intake regulation in obesity. PMID:25258406

  10. Voltammetric characterization of Hg2+ ion behaviour in acid media on different electrodes

    OpenAIRE

    Nemtoi Gh.; Cretescu Ig.; Breaban Iuliana; Verestiuc P.C.; Tucaliuc Oana-Maria

    2014-01-01

    This article presents some aspects related to the cathodic discharge of the mercuric ion provided from HgCl2 into an aqueous solution of 0.1 M H2SO4 on different types of electrodes: gold disc electrode (GDE), carbon paste electrode (CPE) and platinum-disk electrode (PDE). Using the rotating disk electrode technique applied on PDE it was established that the cathodic discharge mechanism for the mercuric ion is based on both process types: mass transport, achieved by diffusion and charge trans...

  11. Stochastic pumping of ions based on colored noise in bacterial channels under acidic stress.

    Science.gov (United States)

    López, M Lidón; Queralt-Martín, María; Alcaraz, Antonio

    2016-07-21

    Fluctuation-driven ion transport can be obtained in bacterial channels with the aid of different types of colored noise including the biologically relevant Lorentzian one. Using the electrochemical rectification of the channel current as a ratchet mechanism we observe transport of ions up to their concentration gradient under conditions similar to that met in vivo, namely moderate pH gradients and asymmetrically charged lipid membranes. We find that depending on the direction of the concentration gradient the channel can pump either cations or anions from the diluted side to the concentrated one. We discuss the possible relevance of this phenomenon for the pH homeostasis of bacterial cells. PMID:27349445

  12. Ionotropic and Metabotropic Proton-Sensing Receptors Involved in Airway Inflammation in Allergic Asthma

    OpenAIRE

    2014-01-01

    An acidic microenvironment has been shown to evoke a variety of airway responses, including cough, bronchoconstriction, airway hyperresponsiveness (AHR), infiltration of inflammatory cells in the lung, and stimulation of mucus hyperproduction. Except for the participation of transient receptor potential vanilloid-1 (TRPV1) and acid-sensing ion channels (ASICs) in severe acidic pH (of less than 6.0)-induced cough and bronchoconstriction through sensory neurons, the molecular mechanisms underly...

  13. Hydrometallurgical process for the recovery of metal values from spent lithium-ion batteries in citric acid media.

    Science.gov (United States)

    Chen, Xiangping; Zhou, Tao

    2014-11-01

    In this paper, a hydrometallurgical process has been proposed to recover valuable metals from spent lithium-ion batteries in citric acid media. Leaching efficiencies as high as 97%, 95%, 94%, and 99% of Ni, Co, Mn, and Li were achieved under the optimal leaching experimental conditions of citric acid concentration of 2 mol L(-1), leaching temperature of 80 °C, leaching time of 90 min, liquid-solid ratio of 30 ml g(-1), and 2 vol. % H2O2. For the metals recovery process, nickel and cobalt were selectively precipitated by dimethylglyoxime reagent and ammonium oxalate sequentially. Then manganese was extracted by Na-D2EHPA and the manganese-loaded D2EHPA was stripped with sulfuric acid. The manganese was recovered as MnSO4 in aqueous phase and D2EHPA could be reused after saponification. Finally, lithium was precipitated by 0.5 mol L(-1) sodium phosphate. Under their optimal conditions, the recovery percentages of Ni, Co, Mn, and Li can reach 98%, 97%, 98%, and 89%, respectively. This is a relatively simple route in which all metal values could be effectively leached and recovered in citric acid media.

  14. Fermentation and recovery of L-glutamic acid from cassava starch hydrolysate by ion-exchange resin column

    Directory of Open Access Journals (Sweden)

    Nampoothiri K. Madhavan

    1999-01-01

    Full Text Available Investigations were carried out with the aim of producing L-glutamic acid from Brevibacterium sp. by utilizing a locally available starchy substrate, cassava (Manihot esculenta Crantz. Initial studies were carried out in shake flasks, which showed that even though the yield was high with 85-90 DE (Dextrose Equivalent value, the maximum conversion yield (~34% was obtained by using only partially digested starch hydrolysate, i.e. 45-50 DE. Fermentations were carried out in batch mode in a 5 L fermenter, using suitably diluted cassava starch hydrolysate, using a 85-90 DE value hydrolysate. Media supplemented with nutrients resulted in an accumulation of 21 g/L glutamic acid with a fairly high (66.3% conversation yield of glucose to glutamic acid (based on glucose consumed and on 81.74% theoretical conversion rate. The bioreactor conditions most conducive for maximum production were pH 7.5, temperature 30°C and an agitation of 180 rpm. When fermentation was conducted in fed-batch mode by keeping the residual reducing sugar concentration at 5% w/v, 25.0 g/L of glutamate was obtained after 40 h fermentation (16% more the batch mode. Chromatographic separation by ion-exchange resin was used for the recovery and purification of glutamic acid. It was further crystallized and separated by making use of its low solubility at the isoelectric point (pH 3.2.

  15. The effect of acid-base clustering and ions on the growth of atmospheric nano-particles.

    Science.gov (United States)

    Lehtipalo, Katrianne; Rondo, Linda; Kontkanen, Jenni; Schobesberger, Siegfried; Jokinen, Tuija; Sarnela, Nina; Kürten, Andreas; Ehrhart, Sebastian; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Sipilä, Mikko; Yli-Juuti, Taina; Duplissy, Jonathan; Adamov, Alexey; Ahlm, Lars; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Downard, Andrew J; Dunne, Eimear M; Flagan, Richard C; Guida, Roberto; Hakala, Jani; Hansel, Armin; Jud, Werner; Kangasluoma, Juha; Kerminen, Veli-Matti; Keskinen, Helmi; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Kupiainen-Määttä, Oona; Laaksonen, Ari; Lawler, Michael J; Leiminger, Markus; Mathot, Serge; Olenius, Tinja; Ortega, Ismael K; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud; Rissanen, Matti P; Ruuskanen, Taina; Santos, Filipe D; Schallhart, Simon; Schnitzhofer, Ralf; Simon, Mario; Smith, James N; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Tomé, António; Vaattovaara, Petri; Vehkamäki, Hanna; Vrtala, Aron E; Wagner, Paul E; Williamson, Christina; Wimmer, Daniela; Winkler, Paul M; Virtanen, Annele; Donahue, Neil M; Carslaw, Kenneth S; Baltensperger, Urs; Riipinen, Ilona; Curtius, Joachim; Worsnop, Douglas R; Kulmala, Markku

    2016-01-01

    The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. We bring these observations into a coherent framework and discuss their significance in the atmosphere. PMID:27197574

  16. Kinetic Study of Esterification of Acetic Acid with n-butanol and isobutanol Catalyzed by Ion Exchange Resin

    Directory of Open Access Journals (Sweden)

    Amrit Pal Toor

    2011-05-01

    Full Text Available Esters are an important pharmaceutical intermediates and very useful perfumery agents. In this study the esterification of acetic acid with n-butanol and iso-butanol over an acidic cation exchange resin, Amberlyst 15 were carried out. The effects of certain parameters such as temperature, catalyst loading, initial molar ratio between reactants on the rate of reaction were studied. The experiments were conducted in a stirred batch reactor in the temperature range of 351.15 K to 366.15K.Variation of parameters on rate of reaction demonstrated that the reaction was intrinsically controlled.The activation energy for the esterification of acetic acid with n-butanol and iso butanol is found to be 28.45 k J/mol and 23.29 kJ/mol respectively. ©2011 BCREC UNDIP. All rights reserved.(Received: 16th December 2010, Revised: 19th March 2011; Accepted: 7th April 2011[How to Cite: A.P. Toor, M. Sharma, G. Kumar, and R. K. Wanchoo. (2011. Kinetic Study of Esterification of Acetic Acid with n-butanol and isobutanol Catalyzed by Ion Exchange Resin. Bulletin of Chemical Reaction Engineering and Catalysis, 6(1: 23-30. doi:10.9767/bcrec.6.1.665.23-30][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.665.23-30 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/665 ] | View in 

  17. Simultaneous removal of acid green 25 and mercury ions from aqueous solutions using glutamine modified chitosan magnetic composite microspheres.

    Science.gov (United States)

    Tao, Xue; Li, Kun; Yan, Han; Yang, Hu; Li, Aimin

    2016-02-01

    In this current work, the magnetic composite microsphere containing glutamine modified chitosan and silica coated Fe3O4 nanoparticles (CS-Gln-MCM) has been successfully prepared and extensively characterized, which is a kind of biodegradable materials. CS-Gln-MCM shows enhanced removal efficiency for both acid green 25 (AG25), an amphoteric dye, and mercury ions (Hg(2+)) from water in the respective while measured pH range compared with chitosan magnetic composite microsphere (CS-MCM) without modification. It is due to the fact that the grafted amino acid provides a variety of additional adsorption active sites and diverse adsorption mechanisms are involved. In AG25 and Hg(2+) aqueous mixture, the modified adsorbents bear preferential adsorption for AG25 over Hg(2+) in strong acidic solutions ascribed to multiple interactions between AG25 and CS-Gln-MCM, such as hydrogen bonding and electrostatic interactions. While, in weak acidic conditions, an efficient simultaneous removal is observed for different adsorption effects involved in aforementioned two pollutants. Besides, CS-Gln-MCM illuminates not only short equilibrium time for adsorption of each pollutant less than 20.0 min but also rapid magnetic separation from water and efficient regeneration after saturated adsorption. Therefore, CS-Gln-MCM bears great application potentials in water treatment. PMID:26618263

  18. The use of ion-selective membranes for the recovery of sulphuric acid out of contaminated solutions. Comparing electrodialysis, electro electrodialysis and diffusion dialysis

    Energy Technology Data Exchange (ETDEWEB)

    Cattoir, S.

    1998-02-01

    The amount of waste arising from dismantled reactors is minimized by decontamination processes. These processes result in contaminated effluents, containing acid and metal salts. The quantity of final waste can be substantially reduced when the acid is extracted out of the decontamination effluents prior to neutralisation. This report discusses three membrane techniques for the displacement of acids out of mixed acid/salt solutions: electrodialysis (ED), electro electrodialysis (EED) and diffusion dialysis (DD). EED uses an electrical potential difference across an anion-selective membrane; DD uses a concentration difference across an anion-selective membrane; ED uses an electrical potential difference, across an anion- and a cation-selective membrane. EED can displace up to 90% of the sulphuric acid, the amount of metal ions in the displaced-acid solution is less than 1% of the ions in the original contaminated solution. Treatment costs are estimated to about 18 Belgian Francs per litre. In DD the purity of the displaced acid is comparable to EED. Treatment costs are about 21 Belgian Francs per litre. In ED 90% acid-displacement is easily reached, but 5% metal ions are also displaced. Treatment costs are about 6 Belgian Francs per litre. Therefore, in spite of the lower purity of the resulting acid, ED is economically speaking the best choice.

  19. Interactions between humic acid and hematite and their effects on metal ion speciation.

    NARCIS (Netherlands)

    Vermeer, A.W.P.

    1996-01-01

    The impact of toxic chemicals (like metal ions) on the environment is a phenomenon that has been recognised as a mayor problem over the last decades. The speciation of these chemicals determines whether or not a contaminated site has to be regarded as dangerous. The fate of the contaminants depends

  20. Stochastic pumping of ions based on colored noise in bacterial channels under acidic stress

    Science.gov (United States)

    López, M. Lidón; Queralt-Martín, María; Alcaraz, Antonio

    2016-07-01

    Fluctuation-driven ion transport can be obtained in bacterial channels with the aid of different types of colored noise including the biologically relevant Lorentzian one. Using the electrochemical rectification of the channel current as a ratchet mechanism we observe transport of ions up to their concentration gradient under conditions similar to that met in vivo, namely moderate pH gradients and asymmetrically charged lipid membranes. We find that depending on the direction of the concentration gradient the channel can pump either cations or anions from the diluted side to the concentrated one. We discuss the possible relevance of this phenomenon for the pH homeostasis of bacterial cells.Fluctuation-driven ion transport can be obtained in bacterial channels with the aid of different types of colored noise including the biologically relevant Lorentzian one. Using the electrochemical rectification of the channel current as a ratchet mechanism we observe transport of ions up to their concentration gradient under conditions similar to that met in vivo, namely moderate pH gradients and asymmetrically charged lipid membranes. We find that depending on the direction of the concentration gradient the channel can pump either cations or anions from the diluted side to the concentrated one. We discuss the possible relevance of this phenomenon for the pH homeostasis of bacterial cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02638a

  1. The acid-catalyzed interaction of melanin with nitrite ions. An EPR investigation

    OpenAIRE

    Matuszak Zenon; Chignell Collin F.; Reszka Krzysztof J.

    2015-01-01

    The interaction of synthetic dihydroxyphenylalanine (DOPA) melanin (DM) with nitrite ions, NO2−, in the pH 3.6–7.0 range, has been investigated using electron paramagnetic resonance (EPR). We found that especially at pH

  2. The ion-sensitive field effect transistor in rapid acid-base titrations

    NARCIS (Netherlands)

    Bos, M.; Bergveld, P.; Veen-Blaauw, van A.M.W.

    1979-01-01

    Ion-sensitive field effect transistors (ISFETs) are used as the pH sensor in rapid acid—base titrations. Titration speeds at least five times greater than those with glass electrodes are possible for accuracies better than ±1%.

  3. Recent advances in secondary ion mass spectrometry of solid acid catalysts : Large zeolite crystals under bombardment

    NARCIS (Netherlands)

    Hofmann, Jan P.; Rohnke, Marcus; Weckhuysen, Bert M.

    2014-01-01

    This Perspective aims to inform the heterogeneous catalysis and materials science community about the recent advances in Time-of-Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) to characterize catalytic solids by taking large model H-ZSM-5 zeolite crystals as a showcase system. SIMS-based techniqu

  4. Agmatine block voltage-gated calcium channels and acid sensing ion channels in the cultured hippocampal neuron

    Institute of Scientific and Technical Information of China (English)

    WENGXie-Chuan; ZHENGJian-Quan; GAIXiao-Dan; LIJin; XiaoWen-Bin

    2004-01-01

    Agrnatine was first identified and characterized as a candidate for CDS (clonidine displacing substance) in the bovine brain in 1994. The following researches demonstrated that agmatine was a widely distributed endogenous substance and performed a lot of biological functions in the central nervous system. The evidence revealed its targets were diverse and its

  5. Simultaneous Qualitative Assessment and Quantitative Analysis of Metabolites (Phenolics, Nucleosides and Amino Acids) from the Roots of Fresh Gastrodia elata Using UPLC-ESI-Triple Quadrupole Ion MS and ESI- Linear Ion Trap High-Resolution MS

    OpenAIRE

    Sha Chen; Jun Qiu Liu; Hui Xiao; Jun Zhang; An Liu

    2016-01-01

    A sensitive, effective and optimized method, based on ultra performance liquid chromatography (UPLC) coupled with ESI-triple quadrupole ion MS and ESI-linear ion trap high-resolution MS, has been developed for the simultaneous quantitative and qualitative determination of phenolics, nucleosides and amino acids in the roots of fresh Gastrodia elata. Optimization of the analytical method provided higher separation efficiency and better peak resolution for the targeted compounds. The simultaneou...

  6. Radiation crosslinked poly (vinyl alcohol/acrylic acid copolymer for removal of heavy metal ions from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Yahya H.F. Al-qudah

    2014-04-01

    Full Text Available Poly(vinyl alcohol and acrylic acid (AAc were copolymerized in different compositions using gamma irradiation. Swelling characteristics of the obtained polymeric hydrogels (PVA/AAc were evaluated and showed reasonable sensitivity to both pH and temperature. The diffusion of water within the hydrogel was found to be of Fickian character, the water molecules may simply diffuse through the polymer network by diffusion processes. The adsorption of Zn2+, Co2+ and Mn2+ ions onto (PVA/AAc has been investigated. The parameters studied including; the effects of pH, contact time and the initial metal ion concentrations by batch method. It was found that the adsorption of Zn2+, Co2+ and Mn2+ ions by PVA/AAc hydrogel is pH-dependent and the maximum sorption of Zn2+, Co2+ and Mn2+ was found to be 388, 245 and 152 mg/g, respectively, at pH 5. The adsorption studies are fitted in various adsorption models such as Langmuir and Freundlich. The kinetic data was tested using pseudo-first-order, pseudo-second-order kinetic models and an intraparticle diffusion model. The correlation results suggested that the pseudo-second-order model was the best choice among all the kinetic models to describe the adsorption behavior.

  7. Xanthomonas campestris FabH is required for branched-chain fatty acid and DSF-family quorum sensing signal biosynthesis.

    Science.gov (United States)

    Yu, Yong-Hong; Hu, Zhe; Dong, Hui-Juan; Ma, Jin-Cheng; Wang, Hai-Hong

    2016-01-01

    Xanthomonas campestris pv. campestris (Xcc), a Gram-negative phytopathogenic bacterium, causes black rot disease of cruciferous vegetables. Although Xcc has a complex fatty acid profile comprised of straight-chain fatty acids and branched-chain fatty acids (BCFAs), and encodes a complete set of genes required for fatty acid synthesis, there is still little known about the mechanism of BCFA synthesis. We reported that expression of Xcc fabH restores the growth of Ralstonia solanacearum fabH mutant, and this allows the R. solanacearum fabH mutant to produce BCFAs. Using in vitro assays, we demonstrated that Xcc FabH is able to condense branched-chain acyl-CoAs with malonyl-ACP to initiate BCFA synthesis. Moreover, although the fabH gene is essential for growth of Xcc, it can be replaced with Escherichia coli fabH, and Xcc mutants failed to produce BCFAs. These results suggest that Xcc does not have an obligatory requirement for BCFAs. Furthermore, Xcc mutants lost the ability to produce cis-11-methyl-2-dodecenoic acid, a diffusible signal factor (DSF) required for quorum sensing of Xcc, which confirms that the fatty acid synthetic pathway supplies the intermediates for DSF signal biosynthesis. Our study also showed that replacing Xcc fabH with E. coli fabH affected Xcc pathogenesis in host plants. PMID:27595587

  8. Characterization of Cu(Ⅱ) Ion Adsorption Behavior of the Polyacrylic Acid-Polyvinylidene Fluoride Blended Polymer

    Institute of Scientific and Technical Information of China (English)

    SONG Laizhou; WANG Jibin; ZHENG Oiuyan; ZHANG Zunju

    2008-01-01

    A blended polymer adsorbent prepared using acrylic acid and polyvinylidene fluoride was used to remove copper from aqueous solutions. The polymer was prepared using thermally induced polymerization and phase inversion. The blended polymer was characterized by X-ray diffraction analysis (XRD), environ- mental scanning electron microscopy (ESEM), X-ray photoelectron spectroscopy (XPS), and N2 adsorp- tion/desorption experiments. The sorption data was fit to linearized adsorption isotherms of the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms models. The batch sorption kinetics was evaluated using pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic reaction models. △H0 is greater than O, △G0 is lower than O, and △S0 is greater than O, which shows that the adsorption of Cu (Ⅱ) by the blended polymer is a spontaneous, endothermic process. The adsorption isotherm fits better to the Freundlich isotherm model and the pseudo-second-order kinetics model gives a better fit to the batch sorp- tion kinetics. The adsorption mechanism is assumed to be ion exchange between the cupric ion and the cerboxylic acid functional group of the blended polymer.

  9. Hair dye-incorporated poly-γ-glutamic acid/glycol chitosan nanoparticles based on ion-complex formation

    Directory of Open Access Journals (Sweden)

    Lee HY

    2011-11-01

    Full Text Available Hye-Young Lee1,*, Young-IL Jeong2,*, Ki-Choon Choi31Anyang Science University, Anyang, Gyeonggi, South Korea; 2Chonnam National University Hwasun Hospital, Jeonnam, South Korea; 3Grassland and Forages Research Center, National Institute of Animal Science, Rural Development Administration, Chungnam, South Korea*These authors contributed equally to this work.Background: p-Phenylenediamine (PDA or its related chemicals are used more extensively than oxidative hair dyes. However, permanent hair dyes such as PDA are known to have potent contact allergy reactions in humans, and severe allergic reactions are problematic.Methods: PDA-incorporated nanoparticles were prepared based on ion-complex formation between the cationic groups of PDA and the anionic groups of poly(γ-glutamic acid (PGA. To reinforce PDA/PGA ion complexes, glycol chitosan (GC was added. PDA-incorporated nanoparticles were characterized using field-emission scanning electron microscopy, Fourier-transform infrared (FT-IR spectroscopy, dynamic light scattering, and powder X-ray diffractometry (XRD.Results: Nanoparticles were formed by ion-complex formation between the amine groups of PDA and the carboxyl groups of PGA. PDA-incorporated nanoparticles are small in size (<100 nm, and morphological observations showed spherical shapes. FT-IR spectra results showed that the carboxylic acid peak of PGA decreased with increasing PDA content, indicating that the ion complexes were formed between the carboxyl groups of PGA and the amine groups of PDA. Furthermore, the intrinsic peak of the carboxyl groups of PGA was also decreased by the addition of GC. Intrinsic crystalline peaks of PDA were observed by XRD. This crystalline peak of PDA was completely nonexistent when nanoparticles were formed by ion complex between PDA, PGA, and GC, indicating that PDA was complexed with PGA and no free drug existed in the formulation. During the drug-release experiment, an initial burst release of PDA was

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

    Science.gov (United States)

    Zhao, Haiyan; Gabbaï, François P.

    2010-11-01

    The search for receptors that can selectively capture small and potentially toxic anions in protic media has sparked a renewed interest in the synthesis and anion-binding properties of polydentate Lewis acids. Seeking new paradigms to enhance the anion affinities of such systems, we synthesized a bidentate Lewis acid that contains a boryl and a telluronium moiety as Lewis acidic sites. Anion-complexation studies indicate that this telluronium borane displays a high affinity for fluoride in methanol. Structural and computational studies show that the unusual fluoride affinity of this bidentate telluronium borane can be correlated with the formation of a B-F --> Te chelate motif supported by a strong lone-pair(F) --> σ*(Te-C) donor-acceptor interaction. These results, which illustrate the viability of heavier chalcogenium centres as anion-binding sites, allow us to introduce a novel strategy for the design of polydentate Lewis acids with enhanced anion affinities.

  11. High-Resolution Electrospray Ionization/Ion Mobility Spectrometer for Detection of Abiotic Amino Acids

    Science.gov (United States)

    Beegle, L. W.; Terrell, C. A.; Kim, H.; Kanik, I.

    2003-01-01

    One of the primary goals of the current NASA thrust in Astrobiology is the detection and identification of organic molecules as part of an in-situ lander platform on the surface of Mars or Europa. The identification of these molecules should help determine whether indigenous organisms exist on the surface of Mars or in an undersea environment on Europa. In addition, a detailed organic chemical inventory of surface and near surface molecules will help elucidate the possibilities of life elsewhere in the Universe. Terrestrial life has, as its backbone, the family of molecules known as the amino acids (AA), and while AA can be found in the terrestrial environments as part of more complex molecules, such as peptides, and proteins, they also exist as individual molecules due to of the hydrolyses of biopolymers. In terrestrial biochemistry, there are 20 principal amino acids which are necessary for life. However, some forms of these molecules can be found in nature synthesized via abiotic process. For example, they are known to exist extraterrestrially as a component of carbonaceous meteorites. The idea that amino acids are readily created by abiotic means has been demonstrated by their positive identification in the Murchison CM2 meteorite, which fell in 1969. This meteorite was analyzed before contamination by terrestrial microbes could result. Three laboratories individually tested parts of the meteorite and concluded that the amino acids present in them were indigenous to the meteorite because, among other reasons, they had equal L- and D- enantiomers. Final identification of the constituents of the Murchison included 33 amino acids which have no known biotic source, 11 amino acids which have limited distribution and 8 (Glycine, Alanine, Valine, Proline, Leucine, Isoleucine, Aspartic Acid, and Glutamic Acid), which readily occur in terrestrial proteins.

  12. The acquisition of Clostridium tyrobutyricum mutants with improved bioproduction under acidic conditions after two rounds of heavy-ion beam irradiation.

    Science.gov (United States)

    Zhou, Xiang; Yang, Zhen; Jiang, Ting-Ting; Wang, Shu-Yang; Liang, Jian-Ping; Lu, Xi-Hong; Wang, Liang

    2016-01-01

    End-product inhibition is a key factor limiting the production of organic acid during fermentation. Two rounds of heavy-ion beam irradiation may be an inexpensive, indispensable and reliable approach to increase the production of butyric acid during industrial fermentation processes. However, studies of the application of heavy ion radiation for butyric acid fermentation engineering are lacking. In this study, a second (12)C(6+) heavy-ion irradiation-response curve is used to describe the effect of exposure to a given dose of heavy ions on mutant strains of Clostridium tyrobutyricum. Versatile statistical elements are introduced to characterize the mechanism and factors contributing to improved butyric acid production and enhanced acid tolerance in adapted mutant strains harvested from the fermentations. We characterized the physiological properties of the strains over a large pH value gradient, which revealed that the mutant strains obtained after a second round of radiation exposure were most resistant to harsh external pH values and were better able to tolerate external pH values between 4.5 and 5.0. A customized second round of heavy-ion beam irradiation may be invaluable in process engineering. PMID:27426447

  13. Medium-chain fatty acid reduces lipid accumulation by regulating expression of lipid-sensing genes in human liver cells with steatosis.

    Science.gov (United States)

    Wang, Baogui; Fu, Jing; Li, Lumin; Gong, Deming; Wen, Xuefang; Yu, Ping; Zeng, Zheling

    2016-01-01

    Accumulation of lipids in the liver can lead to cell dysfunction and steatosis, an important factor in pathogenesis causing non-alcoholic fatty liver disease. The mechanisms related to lipid deposition in the liver, however, remain poorly understood. This study was aimed to investigate the effects of medium-chain fatty acid (MCFA) on the lipolysis and expression of lipid-sensing genes in human liver cells with steatosis. A cellular steatosis model, which is suitable to experimentally investigate the impact of fat accumulation in the liver, was established in human normal liver cells (LO2 cells) with a mixture of free fatty acids (oleate/palmitate, 2:1) at 200 μm for 24 h incubation. MCFA was found to down-regulate expression of liver X receptor-α, sterol regulatory element binding protein-1, acetyl-CoA carboxylase, fatty acid synthase, CD 36 and lipoprotein lipase in this cellular model, and have positive effects on adipose triglyceride lipase and hormone-sensitive lipase. These results suggest that MCFA may reduce lipid accumulation by regulating key lipid-sensing genes in human liver cells with steatosis. PMID:26932533

  14. Molecular mechanisms of calcium-sensing receptor-mediated calcium signaling in the modulation of epithelial ion transport and bicarbonate secretion.

    Science.gov (United States)

    Xie, Rui; Dong, Xiao; Wong, Chase; Vallon, Volker; Tang, Bo; Sun, Jun; Yang, Shiming; Dong, Hui

    2014-12-12

    Epithelial ion transport is mainly under the control of intracellular cAMP and Ca(2+) signaling. Although the molecular mechanisms of cAMP-induced epithelial ion secretion are well defined, those induced by Ca(2+) signaling remain poorly understood. Because calcium-sensing receptor (CaSR) activation results in an increase in cytosolic Ca(2+) ([Ca(2+)]cyt) but a decrease in cAMP levels, it is a suitable receptor for elucidating the mechanisms of [Ca(2+)]cyt-mediated epithelial ion transport and duodenal bicarbonate secretion (DBS). CaSR proteins have been detected in mouse duodenal mucosae and human intestinal epithelial cells. Spermine and Gd(3+), two CaSR activators, markedly stimulated DBS without altering duodenal short circuit currents in wild-type mice but did not affect DBS and duodenal short circuit currents in cystic fibrosis transmembrane conductance regulator (CFTR) knockout mice. Clotrimazole, a selective blocker of intermediate conductance Ca(2+)-activated K(+) channels but not chromanol 293B, a selective blocker of cAMP-activated K(+) channels (KCNQ1), significantly inhibited CaSR activator-induced DBS, which was similar in wild-type and KCNQ1 knockout mice. HCO3 (-) fluxes across epithelial cells were activated by a CFTR activator, but blocked by a CFTR inhibitor. CaSR activators induced HCO3 (-) fluxes, which were inhibited by a receptor-operated channel (ROC) blocker. Moreover, CaSR activators dose-dependently raised cellular [Ca(2+)]cyt, which was abolished in Ca(2+)-free solutions and inhibited markedly by selective CaSR antagonist calhex 231, and ROC blocker in both animal and human intestinal epithelial cells. Taken together, CaSR activation triggers Ca(2+)-dependent DBS, likely through the ROC, intermediate conductance Ca(2+)-activated K(+) channels, and CFTR channels. This study not only reveals that [Ca(2+)]cyt signaling is critical to modulate DBS but also provides novel insights into the molecular mechanisms of CaSR-mediated Ca(2+)-induced

  15. Structural evolution of trimesic acid (TMA)/Zn2 + ion network on Au(111) to final structure of (10√3 × 10√3)

    Science.gov (United States)

    Kim, Jandee; Lee, Jaesung; Rhee, Choong Kyun

    2016-02-01

    Presented is a scanning tunneling microscopy (STM) study of structural evolution of TMA/Zn2 + ion network on Au(111) to the final structure of (10√3 × 10√3) during solution phase post-modification of pristine trimesic acid (TMA) network of a (5√3 × 5√3) structure with Zn2 + ions. Coordination of Zn2 + ions into adsorbed TMA molecules transforms crown-like TMA hexamers in pristine TMA network to chevron pairs in TMA/Zn2 + ion network. Two ordered transient structures of TMA/Zn2 + ion network were observed. One is a (5√7 × 5√7) structure consisting of Zn2 + ion-containing chevron pairs and Zn2 + ion-free TMA dimers. The other is a (5√39 × 5√21) structure made of chevron pairs and chevron-pair-missing sites. An STM image showing domains of different stages of crystallization of chevron pairs demonstrates that the TMA/Zn2 + network before reaching to the final one is quite dynamic. The observed structural evolution of the TMA/Zn2 + ion network is discussed in terms of modification of configurations of adsorbed TMA as accommodating Zn2 + ions and re-ordering of Zn2 + ion-containing chevron pairs.

  16. Silicon nanowire ion sensitive field effect transistor with integrated Ag/AgCl electrode: pH sensing and noise characteristics.

    Science.gov (United States)

    Kim, Sungho; Rim, Taiuk; Kim, Kihyun; Lee, Unsang; Baek, Eunhye; Lee, Hojoon; Baek, Chang-Ki; Meyyappan, M; Deen, M Jamal; Lee, Jeong-Soo

    2011-12-01

    We have fabricated Si nanowire (SiNW) based ion-sensitive field effect transistors (ISFETs) for biosensing applications. The ability to prepare a large number of sensors on a wafer, the use of standard silicon microfabrication techniques resulting in cost savings, and potential high sensitivity are significant advantages in favor of nanoscale SiNW ISFETs. The SiNW ISFETs with embedded Ag/AgCl reference electrode were fabricated on a standard silicon-on-insulator wafer using electron-beam lithography and conventional semiconductor processing technology. The current-voltage characteristics show an n-type FET behavior with a relatively high on/off current ratio, reasonable sub-threshold swing value, and low gate-leakage current. The pH responses of the ISFETs with different pH solutions were characterized at room temperature which showed a clear lateral shift of the drain current vs. gate voltage curve with a change in the pH value of the solution and a sensitivity of 40 mV pH(-1). The low frequency noise characteristics were investigated to evaluate the signal to noise ratio and sensing limit of the devices. PMID:22068238

  17. Study of the nucleation and growth of antibiotic labeled Au NPs and blue luminescent Au8 quantum clusters for Hg2+ ion sensing, cellular imaging and antibacterial applications

    Science.gov (United States)

    Khandelwal, Puneet; Singh, Dheeraj K.; Sadhu, Subha; Poddar, Pankaj

    2015-11-01

    Herein, we report a detailed experimental study supported by DFT calculations to understand the mechanism behind the synthesis of cefradine (CFD - an antibiotic) labeled gold nanoparticles (Au NPs) by employing CFD as both a mild reducing and capping agent. The analysis of the effect of growth conditions reveals that a higher concentration of HAuCl4 results in the formation of an increasing fraction of anisotropic structures, higher temperature leads to the formation of quasi-spherical particles instead of anisotropic ones, and larger pH leads to the formation of much smaller particles. The cyclic voltammetry (CV) results show that when the pH of the reaction medium increases from 4 to 6, the reduction potential of CFD increases which leads to the synthesis of nanoparticles (in a pH 4 reaction) to quantum clusters (in a pH 6 reaction). The MALDI-TOF mass spectrometry results of supernatant of the pH 6 reaction indicate the formation of [Au8(CFD)2S6] QCs which show fluorescence at ca. 432 nm with a Stokes shift of ca. 95 nm. The blue luminescence from Au8 QCs was applied for sensing of Hg2+ ions on the basis of an aggregation-induced fluorescence quenching mechanism and offers good selectivity and a high sensitivity with a limit of detection ca. 2 nM which is lower than the detection requirement of 10 nM by the U.S. EPA and 30 nM by WHO for drinking water. We have also applied the sensing probe to detect Hg2+ ions in bacterial samples. Further, we have investigated the antibacterial property of as-synthesized Au NPs using MIC, growth curve and cell survival assay. The results show that Au NPs could reduce the cell survival very efficiently rather than the cell growth in comparison to the antibiotic itself. The scanning electron microscopy study shows the degradation and blebbing of the bacterial cell wall upon exposure with Au NPs which was further supported by fluorescence microscopy results. These Au NPs did not show reactive oxygen species generation. We believe

  18. Synthesis and Coordination Chemistry of a Phosphine-Decorated Fluorescein: "Double Turn-On" Sensing of Gold(III) Ions in Water.

    Science.gov (United States)

    Christianson, Anna M; Gabbaï, François P

    2016-06-20

    Although phosphine ligands are ubiquitous in transition metal chemistry, few reports of fluorescent phosphines exist that explore the effect of metal coordination on the photophysical properties of a phosphine-bound fluorescent group. The coordination chemistry of a derivative of fluorescein decorated with an o-phenylene-linked phosphine group has been studied with late transition metals. An Au(I) complex of the phosphine-decorated fluorescein has been structurally characterized, showing that the metal center is held closely over the plane of the fluorophore. Despite the presence of the heavy metal center, however, the phosphine-gold complex displays greatly increased fluorescence compared to the free ligand, in which photoelectron transfer from the lone-pair-bearing phosphine causes low emission. The phosphine-decorated fluorescein ligand was tested in a simple sensing system for metal ions in aqueous solution and shows a "turn-on" response to Au, Ag, and Hg, with an especially dramatic response to Au(III) species. The selectivity for Au(III) was determined to be the result of a "double turn-on" response that is both reaction- and coordination-based. PMID:27267582

  19. Synthesis and Coordination Chemistry of a Phosphine-Decorated Fluorescein: "Double Turn-On" Sensing of Gold(III) Ions in Water.

    Science.gov (United States)

    Christianson, Anna M; Gabbaï, François P

    2016-06-20

    Although phosphine ligands are ubiquitous in transition metal chemistry, few reports of fluorescent phosphines exist that explore the effect of metal coordination on the photophysical properties of a phosphine-bound fluorescent group. The coordination chemistry of a derivative of fluorescein decorated with an o-phenylene-linked phosphine group has been studied with late transition metals. An Au(I) complex of the phosphine-decorated fluorescein has been structurally characterized, showing that the metal center is held closely over the plane of the fluorophore. Despite the presence of the heavy metal center, however, the phosphine-gold complex displays greatly increased fluorescence compared to the free ligand, in which photoelectron transfer from the lone-pair-bearing phosphine causes low emission. The phosphine-decorated fluorescein ligand was tested in a simple sensing system for metal ions in aqueous solution and shows a "turn-on" response to Au, Ag, and Hg, with an especially dramatic response to Au(III) species. The selectivity for Au(III) was determined to be the result of a "double turn-on" response that is both reaction- and coordination-based.

  20. Fluorescence characterization of metal ion-humic acid interactions in soils amended with composted municipal solid wastes

    Energy Technology Data Exchange (ETDEWEB)

    Plaza, Cesar; Polo, Alfredo [Consejo Superior de Investigaciones Cientificas, Centro de Ciencias Medioambientales, Madrid (Spain); Brunetti, Gennaro; Senesi, Nicola [University of Bari, Dipartimento di Biologia e Chimica Agroforestale ed Ambientale, Bari (Italy)

    2006-12-15

    Fluorescence spectroscopy has been used to probe the structural properties and Cu(II), Zn(II), Cd(II), and Pb(II)-binding behavior of humic acid (HA)-like fractions isolated from a municipal solid waste compost (MSWC) and HAs from unamended and MSWC-amended soils. The main feature of the fluorescence spectra, in the form of emission-excitation matrix (EEM) plots, was a broad peak with the maximum centered at an excitation/emission wavelength pair that was much shorter (340/437 nm) for MSWC-HA than for unamended and MSWC-amended soil HAs (455/513 and 455/512 nm, respectively). Fluorescence intensity for MSWC-amended soil HA was less than that for unamended soil HA. These results were indicative of more aromatic ring polycondensation and humification of soil HAs, and of partial incorporation of simple and low-humified components of MSWC-HA into native soil HA, as a result of MSWC amendment. Titrations of HAs with Cu(II), Zn(II), Cd(II), and Pb(II) ions at pH 6 and ionic strength 0.1 mol L{sup -1} resulted in a marked decrease of the fluorescence intensities of untreated HAs. By successfully fitting a single-site fluorescence-quenching model to titration data, the metal ion complexing capacities of each HA and the stability constants of metal ion-HA complexes were obtained. The binding capacities and stability constants of MSWC-HA were smaller than those of the unamended soil HA. Application of MSWC to soil slightly reduced the metal-ion-binding capacities and affinities of soil HAs. (orig.)

  1. Strong Relationships in Acid-Base Chemistry – Modeling Protons Based on Predictable Concentrations of Strong Ions, Total Weak Acid Concentrations, and pCO2

    Science.gov (United States)

    Kellum, John A.

    2016-01-01

    Understanding acid-base regulation is often reduced to pigeonholing clinical states into categories of disorders based on arterial blood sampling. An earlier ambition to quantitatively explain disorders by measuring production and elimination of acid has not become standard clinical practice. Seeking back to classical physical chemistry we propose that in any compartment, the requirement of electroneutrality leads to a strong relationship between charged moieties. This relationship is derived in the form of a general equation stating charge balance, making it possible to calculate [H+] and pH based on all other charged moieties. Therefore, to validate this construct we investigated a large number of blood samples from intensive care patients, where both data and pathology is plentiful, by comparing the measured pH to the modeled pH. We were able to predict both the mean pattern and the individual fluctuation in pH based on all other measured charges with a correlation of approximately 90% in individual patient series. However, there was a shift in pH so that fitted pH in general is overestimated (95% confidence interval -0.072–0.210) and we examine some explanations for this shift. Having confirmed the relationship between charged species we then examine some of the classical and recent literature concerning the importance of charge balance. We conclude that focusing on the charges which are predictable such as strong ions and total concentrations of weak acids leads to new insights with important implications for medicine and physiology. Importantly this construct should pave the way for quantitative acid-base models looking into the underlying mechanisms of disorders rather than just classifying them. PMID:27631369

  2. 离子色谱法测定工业废气中的甲酸、乙酸和丙酸%Industrial waste gas by ion chromatography determination of formic acid, acetic acid and propionic acid

    Institute of Scientific and Technical Information of China (English)

    吴红星

    2013-01-01

    建立了用离子色谱法测定工业废气中甲酸、乙酸和丙酸的新方法,常规无机阴离子对本方法的测定没有干扰。本方法分析速度快,所需样品量少,且无需要复杂的前处理,简便、灵敏、可靠。%established by ion chromatography determination of formic acid , acetic acid and propionic acid in industrial waste gas , a new method for the determination of inorganic anions , the conventional method without interference .This method is fast , small quantity of sam-ple, and no need of complicated pretreatment , simple, sensitive, reliable.

  3. Immobilization of pyrene on quartz plate surface via a flexible long spacer and its sensing properties to dicarboxylic acids

    Institute of Scientific and Technical Information of China (English)

    GAO Lining; FANG Yu; Lü Fengting; DING Liping

    2004-01-01

    A novel photo-induced luminescence film has been prepared by immobilizing pyrene on quartz plate surface via a flexible long spacer, 1,3-diaminopropane and 3-glycidoxypropyl trimethoxysilane. The film shows combined monomer and excimer emission of pyrene in both wet and dry states. Steady-state and time-resolved fluorescence emission measurements demonstrated that the excimer emission mainly came from direct excitation of ground state dimers, and/or monomers in aggregated state. Classical Birks' scheme plays little role in the formation of the excimers. The structures of the excimers formed during the excitation are complex. Both "standard excimer" of sandwich-like fully overlapped structure and "distorted excimer" of partially overlapped structure exist in the excited state of the fluorophore. The emission of the film is sensitive to the presence of dicarboxylic acids, including ethanedioic acid, malonic acid, succinic acid, etc. The emission in the monomer and excimer region increases along with increasing the concentration of the dicarboxylic acids. The time needed for the emission to reach equilibrium depends on the nature of the acids. It has been shown that the longer the chain length of the acids, the more the time needed. This observation is explained by considering the conformational reorganization of the immobilized pyrene due to insertion of the dicarboxylic acids into the space between neighboring spacers. Experimental results from similar studies using formic acid and acetic acid are in support of this explanation. Furthermore, the response of the film to dicarboxylic acids is reversible.

  4. Simultaneous voltammetric detection of ascorbic acid and uric acid at a carbon-paste modified electrode incorporating thionine-nafion ion-pair as an electron mediator

    Energy Technology Data Exchange (ETDEWEB)

    Shahrokhian, Saeed [Department of Chemistry, Sharif University of Technology, Tehran 11365-9516 (Iran, Islamic Republic of)]. E-mail: shahrokhian@sharif.edu; Ghalkhani, Masoumeh [Department of Chemistry, Sharif University of Technology, Tehran 11365-9516 (Iran, Islamic Republic of)

    2006-03-05

    The electrochemical behavior of ascorbic acid (AA) and uric acid (UA) at the surface of a carbon-paste electrode modified with incorporate thionine-nafion ion-paired was thoroughly investigated. The results show the presence of nafion inside the matrix of modified electrode, because of the effective ion-pairing and hydrophobic interactions, significantly enhances the stability of thionine as an electron mediator inside the modified electrode. A high reproducibility in voltammetric response to analyte species results because of this enhancement. The cyclic voltammetric studies using the prepared modified electrode show the best electrocatalytic property for the electro-oxidation of AA and noticeable decrease in anodic overpotential. Although the catalytic effect is observed to some extent for UA, the property cannot be seen for other biologically reducing agents such as cysteine. The voltammetric studies using the thionine-nafion modified electrode show two well-resolved anodic peaks for AA and UA, revealing the possibility of the simultaneous electrochemical detection of these compounds in the presence of biological thiols. The detection limits of 5 x 10{sup -8} and 5 x 10{sup -7} M were obtained in differential pulse voltammetric (DPV) measurements for UA and AA, respectively. Spectrophotometric investigations were used to confirm the selective catalytic effect of thionine in oxidation of AA and to some extent, UA. The detection system is stable (R.S.D. for the slope of the calibration curves was less than 4% for six measurements in one month) and is of high selectivity for electro-oxidation of AA and UA in complex biological and clinical matrices. The prepared modified electrode is applied for the DPV measurement of AA in pharmaceutical preparations. Also, the electrode is used to determine UA in human urine and serum samples and recovery of the amounts of UA added to these complex samples.

  5. Purification of Lactic Acid by Heterogeneous Catalytic Distillation Using Ion-exchange Resins

    Institute of Scientific and Technical Information of China (English)

    马利; 张阳; 杨基础

    2005-01-01

    The purification of lactic acid based on the esterification of raw lactic acid from fermentation broth and then the catalytic distillation hydrolysis of methyl lactate simultaneously to achieve pure lactic acid is reported. The esterification kinetics of lactic acid with methanol catalyzed by strong-acid cation-exchange resins (Amberlyst-15,D001, D002, NKC, 002) was studied under the condition that simulates the real catalytic environment. Experimental results were correlated by a Langmuir-Hinselwood model and the nonideality of the solution was taken into account by using activities calculated by the universal quasichemical functional group activity coefficient (UNIFAC) method.A good agreement between the model and the experimental data was achieved. Continuous purification experiments were conducted to find the optimum column configuration and operation condition for the system. The effects of various parameters, e.g. the length of different section of the column, feed rate and ratio of reactants, packing material and catalyst type, were studied. This novel system shows good separation results in lab scale, and is potential for industrial application.

  6. Leaching lithium from the anode electrode materials of spent lithium-ion batteries by hydrochloric acid (HCl).

    Science.gov (United States)

    Guo, Yang; Li, Feng; Zhu, Haochen; Li, Guangming; Huang, Juwen; He, Wenzhi

    2016-05-01

    Spent lithium-ion batteries (LIBs) are considered as an important secondary resource for its high contents of valuable components, such as lithium and cobalt. Currently, studies mainly focus on the recycling of cathode electrodes. There are few studies concentrating on the recovery of anode electrodes. In this work, based on the analysis result of high amount of lithium contained in the anode electrode, the acid leaching process was applied to recycle lithium from anode electrodes of spent LIBs. Hydrochloric acid was introduced as leaching reagent, and hydrogen peroxide as reducing agent. Within the range of experiment performed, hydrogen peroxide was found to have little effect on lithium leaching process. The highest leaching recovery of 99.4wt% Li was obtained at leaching temperature of 80°C, 3M hydrochloric acid and S/L ratio of 1:50g/ml for 90min. The graphite configuration with a better crystal structure obtained after the leaching process can also be recycled.

  7. Kinetic energy releases of small amino acids upon interaction with keV ions

    International Nuclear Information System (INIS)

    In chromatin, DNA is tightly packed into one complex together with histone and non-histone proteins. These proteins are known to protect the DNA against indirect and to some extent even direct radiation damage. Radiation action upon amino acids is thus one of the primary steps in biological radiation action. In this paper we investigate the ionization and fragmentation of the gas-phase amino acids glycine, alanine and valine upon interaction with keV α-particles. High resolution coincidence time-of-flight mass spectrometry is used to determine the dominant fragmentation channels as well as fragment kinetic energies. (authors)

  8. Kinetic energy releases of small amino acids upon interaction with keV ions

    Energy Technology Data Exchange (ETDEWEB)

    Bari, S.; Alvarado, F.; Postma, J.; Sobocinski, P.; Hoekstra, R.; Schlatholter, T. [Groningen Univ., KVI Atomic Physics (Netherlands); Schlatholter, T. [Universites P. et M. Curie and D. Diderot, INSP, CNRS UMR 75-88, 75 - Paris (France)

    2009-01-15

    In chromatin, DNA is tightly packed into one complex together with histone and non-histone proteins. These proteins are known to protect the DNA against indirect and to some extent even direct radiation damage. Radiation action upon amino acids is thus one of the primary steps in biological radiation action. In this paper we investigate the ionization and fragmentation of the gas-phase amino acids glycine, alanine and valine upon interaction with keV {alpha}-particles. High resolution coincidence time-of-flight mass spectrometry is used to determine the dominant fragmentation channels as well as fragment kinetic energies. (authors)

  9. Analysis of molecular species of triacylglycerols from vegetable oils containing fatty acids with non-methylene-interrupted double bonds, by HPLC in the silver-ion mode

    Energy Technology Data Exchange (ETDEWEB)

    Joh, Y.; Kim, S. [Dong A Univ., Pusan (Korea, Republic of)

    1998-10-20

    The possibilities for application of silver ion HPLC to analysis of the triacylglycerols containing conjugate trienoic acids and {Delta}{sup 5}-polymethylene-interrupted acids and proportions of triacylglycerol fractions obtained by silver-ion HPLC from the seed oil of Momordica charantia double bonds were examined, respectively. The triacylglycerols of seed oils containing conjugate trienoic acids such as {alpha}-eleostearic acid (C{sub 18:3 9c,11t,13t}) and punicic acid (C{sub 18:3} {sub 9c,11t,13c}) were resolved by silver-ion HPLC. Fractions were fractionated on the basis of the number and configuration of double bonds in the species, and the elution profile is quite different from that of the species comprising exclusively saturated and unsaturated fatty acids with methylene-interrupted double bonds ; for instance, the species (DT(c2)) composed of one dienoic acid and two conjugate trienoic acids eluted much earlier than the species (D{sub 2}T{sub c}) composed of two dienoic acids and one conjugate trienoic acid, in spite of having larger number of double bonds. This means that the interaction of conjugate double bonds with silver ions is weaker than that of methylene-interrupted double bonds, presumably because of the delocalization of {pi}-electrons in conjugate double bonds. In this instance, the strength of interaction of a conjugate trienoic double bond system with silver ions seemed to be between that of methylene-interrupted dienoic and monoenoic double bond systems. Triacylglycerols of the seeds of Ginkgo biloba have been resolved by HPLC in the silver-ion mode according to the number and position of double bonds. In this instance, the strength of interaction between the {pi}-electrons of double bonds in the fatty acyl residues and silver ions is in the order; C{sub 18:3{omega}3}>C(20:3){Delta}{sup 5,11,14}C{sub 18:3}{Delta}{sup 5,9,12}>= C{sub 18:2{omega}6}>C{sub 18:2}{Delta}{sup 5,9}>C{sub 18:1{omega}9}>C{sub 18:1ome= ga7}. 49 refs., 2 figs., 2 tabs.

  10. Development Of Ion Chromatography Methods To Support Testing Of The Glycolic Acid Reductant Flowsheet In The Defense Waste Processing Facility

    Energy Technology Data Exchange (ETDEWEB)

    Wiedenman, B. J.; White, T. L.; Mahannah, R. N.; Best, D. R.; Stone, M. E.; Click, D. R.; Lambert, D. P.; Coleman, C. J.

    2013-10-01

    Ion Chromatography (IC) is the principal analytical method used to support studies of Sludge Reciept and Adjustment Tank (SRAT) chemistry at DWPF. A series of prior analytical ''Round Robin'' (RR) studies included both supernate and sludge samples from SRAT simulant, previously reported as memos, are tabulated in this report.2,3 From these studies it was determined to standardize IC column size to 4 mm diameter, eliminating the capillary column from use. As a follow on test, the DWPF laboratory, the PSAL laboratory, and the AD laboratory participated in the current analytical RR to determine a suite of anions in SRAT simulant by IC, results also are tabulated in this report. The particular goal was to confirm the laboratories ability to measure and quantitate glycolate ion. The target was + or - 20% inter-lab agreement of the analyte averages for the RR. Each of the three laboratories analyzed a batch of 12 samples. For each laboratory, the percent relative standard deviation (%RSD) of the averages on nitrate, glycolate, and oxalate, was 10% or less. The three laboratories all met the goal of 20% relative agreement for nitrate and glycolate. For oxalate, the PSAL laboratory reported an average value that was 20% higher than the average values reported by the DWPF laboratory and the AD laboratory. Because of this wider window of agreement, it was concluded to continue the practice of an additional acid digestion for total oxalate measurement. It should also be noted that large amounts of glycolate in the SRAT samples will have an impact on detection limits of near eluting peaks, namely Fluoride and Formate. A suite of scoping experiments are presented in the report to identify and isolate other potential interlaboratory disceprancies. Specific ion chromatography inter-laboratory method conditions and differences are tabulated. Most differences were minor but there are some temperature control equipment differences that are significant leading to

  11. Kinetic and thermodynamic studies on the adsorption of U(VI) ions on densely crosslinked poly(methacrylic acid) from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Oezeroglu, C.; Keceli, G. [Istanbul Univ., Dept. of Chemistry, Avcilar Istanbul (Turkey)

    2009-07-01

    In this study, densely crosslinked poly(methacrylie acid) was used to adsorb uranium(VI) ions from aqueous solution. For this purpose, the crosslinked copolymer of ethylene glycol dimethacrylate (EGDM) and methacrylic acid (MA) containing 25% (w/w) methacrylic acid (MA) was synthesized by using dibenzoyl peroxide-N,N-dimethylaniline (BPO-DMA) initiator system at room temperature. The adsorption of uranium(Vl) ions on the copolymer sample (0.02 g copolymer/5 mL solution of U(VI) ions) was carried out in a batch reactor. The parameters which effect the uranium adsorption process, such as, contact time. pH of solution, initial uranium(VI) concentration and temperature were investigated. It was observed that an increase in these parameters enhanced the removal of U(VI) ions from aqueous solution. The adsorption data were modelled by the Freundlich. Langmuir and Dubinin-Radushkevich (D-R) isotherms. The adsorption capacity of the crosslinked copolymer and free energy change were calculated by using D-R isotherms. Thermodynamic parameters ({delta}H , {delta}S and {delta}G ) were determined for the adsorption of U(VI) ions from aqueous solutions by the crosslinked copolymer bearing methacrylic acid functional groups. Experimental adsorption data were analyzed using sorption kinetic models of the pseudo-first order and pseudo-second order kinetic models. It was observed that pseudo-second order kinetic model provided a high goodness of fit with experimental data for the adsorption of U(VI) ions on the crosslinked copolymer bearing methacrylic acid functional groups. The densely crosslinked poly(methacrylic acid) might be of interest in large scale uranium removals from aqueous solution, since it had high uranyl sorption capacities ranging from 0.16 to 2.37 mmol/g copolymer at pH 2.7 (293 K). (orig.)

  12. Neutralization and Acid Dissociation of Hydrogen Carbonate Ion: A Thermochemical Approach

    Science.gov (United States)

    Koga, Nobuyoshi; Shigedomi, Kana; Kimura, Tomoyasu; Tatsuoka, Tomoyuki; Mishima, Saki

    2013-01-01

    A laboratory inquiry into the thermochemical relationships in the reaction between aqueous solutions of NaHCO[subscript 3] and NaOH is described. The enthalpy change for this reaction, delta[subscript r]H, and that for neutralization of strong acid and NaOH(aq), delta[subscript n]H, are determined calorimetrically; the explanation for the…

  13. Kinetic energy releases of small amino acids upon interaction with keV ions

    NARCIS (Netherlands)

    Bari, S.; Alvarado, F.; Postma, J.; Sobocinski, P.; Hoekstra, R.; Schlatholter, T.

    2009-01-01

    In chromatin, DNA is tightly packed into one complex together with histone and non-histone proteins. These proteins are known to protect the DNA against indirect and to some extent even direct radiation damage. Radiation action upon amino acids is thus one of the primary steps in biological radiatio

  14. Assembled diglycolamide for f-element ions sequestration at high acidity

    NARCIS (Netherlands)

    Chavan, V.; Thekkethil, V.; Pandey, A.K.; Iqbal, M.; Huskens, J.; Singh Meena, S.; Goswami, A.; Verboom, W.

    2014-01-01

    Diglycolamides (DGA) form reverse-micellar type of supramolecular aggregates upon equilibration with a nitric acid solution that enhances DGA affinity extraordinary towards f-elements. To mimic DGA aggregates, DGA molecules have been preorganized on chemical platforms to form assemblies having a goo

  15. Prostatic acid phosphatase: structural aspects of inhibition by L-(+)-tartrate ions.

    Science.gov (United States)

    Lovelace, L; Lewiński, K; Jakob, C G; Kuciel, R; Ostrowski, W; Lebioda, L

    1997-01-01

    The crystal structure of the complex between rat-prostatic acid phosphatase (PAP) and L-(+)-tartrate (Lindqvist et al., J. Biol. Chem., 1993, 268, 20744-20746) contains the model of the ligand with incorrect chirality. We report here the correct model and discuss the relation between this model and the model of the inhibitory complexes between PAP and oxy-anions.

  16. Evaluation of ALIX as an ion exchanger for selective separation of Cs from acidic solution

    International Nuclear Information System (INIS)

    ALIX (Advance Lipophilic Ion Exchanger) is an ammonium molybdophosphate (AMP) based composite material in which AMP is encapsulated in egg box structure formed by hydrophobic polymeric inert substrate. This structure brings the high porosity and mechanical strength. ALIX is loaded with 80% (w/w) of AMP. Studies were carried out to understand the effect of void volume on distribution coefficient of Cs (KdCs). It was found that void volume does not influence the concentration of Cs. Maximum exchange capacity of Cs (CEC) was found to be 0.63 meq/gm. (author)

  17. Dipeptide Formation from Amino Acid Monomer Induced by keV Ion Irradiation: An Implication for Physicochemical Repair by Radiation Itself

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; YUAN Hang; WANG Xiangqin; YU Zengliang

    2008-01-01

    An identification of Phe dipeptide from L-phenylalanine monomers after keV nitro-gen and argon ion implantation, by using the HPLC (high performance liquid chromatography) and LC-MS(liquid chromatography mass spectrometer) methods is reported. The results showed a similar yield behavior for both ion species, namely: 1) the yield of dipeptides under alkalescent conditions was distinctly higher than that under acidic or neutral conditions; 2) for different ion species, the dose-yield curves tracked a similar trend which was called a counter-saddle curve. The dipeptide formation may implicate a recombination repair mechanism of damaged biomolecules that energetic ions have left in their wake. Accordingly a physicochemical self-repair mechanism by radiation itself for the ion-beam radiobiological effects is proposed.

  18. Remote sensing and DEM-based approach for updating acid sulphate soil distribution: an example in Pearl River Estuary, South China

    Science.gov (United States)

    Chen, Shuisen; Liu, Qinhuo; Chen, Liangfu; Wang, Juan

    2004-11-01

    There is more population but less cultivated land in the Pearl River estuary region South China. The commissariat provision in the region is not enough for a long amount of time. The distribution of acid sulphate soil (ASS) is constantly changing for the Pearl River Delta as it expands seaward. It is important to research the ASS for land use planning and crop potentiality in appraising the Pearl River estuary. As more than 20 years have passed since the soil type maps and reports of the 2nd national soil investigation were made, soil quality problems have appeared. These problems can be solved by modern remote sensing and GIS techniques. The ASS units are updated by the analysis of the new remote sensing images and the application of digital elevation model (DEM). Changes in the ASS area are also produced by GIS. Finally, a practical distribution of ASS is presented in the map. The authors found out that the results of remote sensing and the GIS methods are of high reliability and spatial conclusiveness by comparing the result data with the past investigation report of soil and some field exploration data.

  19. Triplex-Forming Peptide Nucleic Acid Probe Having Thiazole Orange as a Base Surrogate for Fluorescence Sensing of Double-stranded RNA.

    Science.gov (United States)

    Sato, Takaya; Sato, Yusuke; Nishizawa, Seiichi

    2016-08-01

    We have developed a new fluorescent sensing probe for double-stranded RNA (dsRNA) by integrating thiazole orange (TO) as a base surrogate into triplex-forming PNA. Our probe forms the thermally stable triplex with the target dsRNA at acidic pH; and the triplex formation is accompanied by the remarkable light-up response of the TO unit. The binding of our probe to the target dsRNA proceeds very rapidly, allowing real-time monitoring of the triplex formation. Importantly, we found the TO base surrogate in our probe functions as a universal base for the base pair opposite the TO unit in the triplex formation. Furthermore, the TO unit is significantly more responsive for the fully matched dsRNA sequence compared to the mismatch-containing sequences, which enables the analysis of the target dsRNA sequence at the single-base pair resolution. The binding and sensing functions of our probe are described for the development of fluorescent probes applicable to sensing biologically relevant dsRNA. PMID:27442229

  20. Optical sensing of 3-phenoxybenzoic acid as a pyrethroid pesticides exposure marker by surface imprinting polymer capped on manganese-doped zinc sulfide quantum dots

    Directory of Open Access Journals (Sweden)

    Vivek Pandey

    2015-09-01

    Full Text Available The present communication deals with the synthesis of luminescent Mn-doped ZnS quantum dots (QDs anchored to surface imprinted polymer for the optical sensing of 3-phenoxy benzoic acid (3-PBA in urine samples. The combination of sensing and surface functionalization not only improves the selectivity of the method, but also increases the optosensing ability of the material for non-phosphorescent substances. The developed material was utilized for the selective and sensitive detection of 3-PBA in urine samples. The proposed method shows good linearity with a regression coefficient (R2 of 0.98. The limit of detection was found to be 0.117 μM. The method has an acceptable precision and accuracy which are found to be less than 8% and 80–90% respectively at three different concentrations. The quenching constant of quantum dot-molecular imprinted polymer was found to be 3.4 times higher to that of the quantum dot-non imprinted polymer (QD-NIP as calculated by Stern–Volmer equation. The sensing method developed has shown immense utility to detect 3-PBA in complex biological samples like urine.

  1. Graphene oxide/nucleic-acid-stabilized silver nanoclusters: functional hybrid materials for optical aptamer sensing and multiplexed analysis of pathogenic DNAs.

    Science.gov (United States)

    Liu, Xiaoqing; Wang, Fuan; Aizen, Ruth; Yehezkeli, Omer; Willner, Itamar

    2013-08-14

    Hybrid systems consisting of nucleic-acid-functionalized silver nanoclusters (AgNCs) and graphene oxide (GO) are used for the development of fluorescent DNA sensors and aptasensors, and for the multiplexed analysis of a series of genes of infectious pathogens. Two types of nucleic-acid-stabilized AgNCs are used: one type includes the red-emitting AgNCs (616 nm) and the second type is near-infrared-emitting AgNCs (775 nm). Whereas the nucleic-acid-stabilized AgNCs do not bind to GO, the conjugation of single-stranded nucleic acid to the DNA-stabilized AgNCs leads to the adsorption of the hybrid nanostructures to GO and to the fluorescence quenching of the AgNCs. By the conjugation of oligonucleotide sequences acting as probes for target genes, or as aptamer sequences, to the nucleic-acid-protected AgNCs, the desorption of the probe/nucleic-acid-stabilized AgNCs from GO through the formation of duplex DNA structures or aptamer-substrate complexes leads to the generation of fluorescence as a readout signal for the sensing events. The hybrid nanostructures are implemented for the analysis of hepatitis B virus gene (HBV), the immunodeficiency virus gene (HIV), and the syphilis (Treponema pallidum) gene. Multiplexed analysis of the genes is demonstrated. The nucleic-acid-AgNCs-modified GO is also applied to detect ATP or thrombin through the release of the respective AgNCs-labeled aptamer-substrate complexes from GO. PMID:23841845

  2. Detection of lysergic acid diethylamide (LSD) in urine by gas chromatography-ion trap tandem mass spectrometry.

    Science.gov (United States)

    Sklerov, J H; Kalasinsky, K S; Ehorn, C A

    1999-10-01

    A confirmatory method for the detection and quantitation of lysergic acid diethylamide (LSD) is presented. The method employs gas chromatography-tandem mass spectrometry (GC-MS-MS) using an internal ionization ion trap detector for sensitive MS-MS-in-time measurements of LSD extracted from urine. Following a single-step solid-phase extraction of 5 mL of urine, underivatized LSD can be measured with limits of quantitation and detection of 80 and 20 pg/mL, respectively. Temperature-programmed on-column injections of urine extracts were linear over the concentration range 20-2000 pg/mL (r2 = 0.999). Intraday and interday coefficients of variation were LSD-positive samples in this laboratory. Comparisons with alternate GC-MS methods and extraction procedures are discussed.

  3. Determination of Uric Acid in Human Urine by Ion-exclusion Chromatography with UV Detection Using Pure Water as Mobile Phase

    Institute of Scientific and Technical Information of China (English)

    侯升杰; 杨成对; 王辉; 田中一彦; 丁明玉

    2012-01-01

    A simple, rapid and accurate ion-exclusion chromatographic method coupled with a UV detector for the determination of uric acid in human urine samples has been developed. The separation was carried out on an ion-exclusion column using only pure water as mobile phase. The detection wavelength was 254 nm and urine sample was injected directly without any pretreatment. Furthermore, the retention behavior of uric acid on the ion-exclusion column was researched when pure water and 1 mmol·L-1 HCI were used as mobile phase, respectively. The stability of uric acid was also further investigated within 28 days, In this method, the linear range of the calibration curve for uric acid was 0.25--100 mg·L-1, and the detection limit calculated at S/N=3 was 0.02mg·L-1 The proposed ion-exclusion chromatographic method has been used for the determination of uric acid in human urine.

  4. Impact of the Ferric Ion and Ferrous Ion Changes on Industrial Boilers Acid Pickling%铁离子、亚铁离子变化对工业锅炉酸洗的影响

    Institute of Scientific and Technical Information of China (English)

    谢桂杰

    2015-01-01

    This paper introduces the source of ferric ion in industrial boiler acid pickling, and proposes to strengthen the chemical monitoring of ferric ion and ferrous ion(Fe3+、Fe2+)by examples, to ensure the safety of acid pickling of boiler and the judgment of end.%介绍工业锅炉酸洗中铁离子的来源,并以实例说明酸洗中应强化对铁离子、亚铁离子(Fe3+、Fe2+)的化学监测,使锅炉酸洗安全进行,及终点的判断。

  5. A Fall in Plasma Free Fatty Acid (FFA) Level Activates the Hypothalamic-Pituitary-Adrenal Axis Independent of Plasma Glucose: Evidence for Brain Sensing of Circulating FFA

    Science.gov (United States)

    Oh, Young Taek; Oh, Ki-Sook; Kang, Insug

    2012-01-01

    The brain responds to a fall in blood glucose by activating neuroendocrine mechanisms for its restoration. It is unclear whether the brain also responds to a fall in plasma free fatty acids (FFA) to activate mechanisms for its restoration. We examined whether lowering plasma FFA increases plasma corticosterone or catecholamine levels and, if so, whether the brain is involved in these responses. Plasma FFA levels were lowered in rats with three independent antilipolytic agents: nicotinic acid (NA), insulin, and the A1 adenosine receptor agonist SDZ WAG 994 with plasma glucose clamped at basal levels. Lowering plasma FFA with these agents all increased plasma corticosterone, but not catecholamine, within 1 h, accompanied by increases in plasma ACTH. These increases in ACTH or corticosterone were abolished when falls in plasma FFA were prevented by Intralipid during NA or insulin infusion. In addition, the NA-induced increases in plasma ACTH were completely prevented by administration of SSR149415, an arginine vasopressin receptor antagonist, demonstrating that the hypothalamus is involved in these responses. Taken together, the present data suggest that the brain may sense a fall in plasma FFA levels and activate the hypothalamic-pituitary-adrenal axis to increase plasma ACTH and corticosterone, which would help restore FFA levels. Thus, the brain may be involved in the sensing and control of circulating FFA levels. PMID:22669895

  6. Alkali Metal Ion Complexes with Phosphates, Nucleotides, Amino Acids, and Related Ligands of Biological Relevance. Their Properties in Solution.

    Science.gov (United States)

    Crea, Francesco; De Stefano, Concetta; Foti, Claudia; Lando, Gabriele; Milea, Demetrio; Sammartano, Silvio

    2016-01-01

    Alkali metal ions play very important roles in all biological systems, some of them are essential for life. Their concentration depends on several physiological factors and is very variable. For example, sodium concentrations in human fluids vary from quite low (e.g., 8.2 mmol dm(-3) in mature maternal milk) to high values (0.14 mol dm(-3) in blood plasma). While many data on the concentration of Na(+) and K(+) in various fluids are available, the information on other alkali metal cations is scarce. Since many vital functions depend on the network of interactions occurring in various biofluids, this chapter reviews their complex formation with phosphates, nucleotides, amino acids, and related ligands of biological relevance. Literature data on this topic are quite rare if compared to other cations. Generally, the stability of alkali metal ion complexes of organic and inorganic ligands is rather low (usually log K  Na(+) > K(+) > Rb(+) > Cs(+). For example, for citrate it is: log K ML = 0.88, 0.80, 0.48, 0.38, and 0.13 at 25 °C and infinite dilution. Some considerations are made on the main aspects related to the difficulties in the determination of weak complexes. The importance of the alkali metal ion complexes was also studied in the light of modelling natural fluids and in the use of these cations as probes for different processes. Some empirical relationships are proposed for the dependence of the stability constants of Na(+) complexes on the ligand charge, as well as for correlations among log K values of NaL, KL or LiL species (L = generic ligand). PMID:26860301

  7. The complete targeted profile of the organic acid intermediates of the citric acid cycle using a single stable isotope dilution analysis, sodium borodeuteride reduction and selected ion monitoring GC/MS.

    Science.gov (United States)

    Mamer, Orval; Gravel, Simon-Pierre; Choinière, Luc; Chénard, Valérie; St-Pierre, Julie; Avizonis, Daina

    2013-01-01

    The quantitative profiling of the organic acid intermediates of the citric acid cycle (CAC) presents a challenge due to the lack of commercially available internal standards for all of the organic acid intermediates. We developed an analytical method that enables the quantitation of all the organic acids in the CAC in a single stable isotope dilution GC/MS analysis with deuterium-labeled analogs used as internal standards. The unstable α-keto acids are rapidly reduced with sodium borodeuteride to the corresponding stable α-deutero-α-hydroxy acids and these, along with their unlabeled analogs and other CAC organic acid intermediates, are converted to their tert-butyldimethylsilyl derivatives. Selected ion monitoring is employed with electron ionization. We validated this method by treating an untransformed mouse mammary epithelial cell line with well-known mitochondrial toxins affecting the electron transport chain and ATP synthase, which resulted in profound perturbations of the concentration of CAC intermediates.

  8. In Vivo Curative and Protective Potential of Orally Administered 5-Aminolevulinic Acid plus Ferrous Ion against Malaria

    Science.gov (United States)

    Suzuki, Shigeo; Hikosaka, Kenji; Balogun, Emmanuel O.; Komatsuya, Keisuke; Niikura, Mamoru; Kobayashi, Fumie; Takahashi, Kiwamu; Tanaka, Tohru; Nakajima, Motowo

    2015-01-01

    5-Aminolevulinic acid (ALA) is a naturally occurring amino acid present in diverse organisms and a precursor of heme biosynthesis. ALA is commercially available as a component of cosmetics, dietary supplements, and pharmaceuticals for cancer diagnosis and therapy. Recent reports demonstrated that the combination of ALA and ferrous ion (Fe2+) inhibits the in vitro growth of the human malaria parasite Plasmodium falciparum. To further explore the potential application of ALA and ferrous ion as a combined antimalarial drug for treatment of human malaria, we conducted an in vivo efficacy evaluation. Female C57BL/6J mice were infected with the lethal strain of rodent malaria parasite Plasmodium yoelii 17XL and orally administered ALA plus sodium ferrous citrate (ALA/SFC) as a once-daily treatment. Parasitemia was monitored in the infected mice, and elimination of the parasites was confirmed using diagnostic PCR. Treatment of P. yoelii 17XL-infected mice with ALA/SFC provided curative efficacy in 60% of the mice treated with ALA/SFC at 600/300 mg/kg of body weight; no mice survived when treated with vehicle alone. Interestingly, the cured mice were protected from homologous rechallenge, even when reinfection was attempted more than 230 days after the initial recovery, indicating long-lasting resistance to reinfection with the same parasite. Moreover, parasite-specific antibodies against reported vaccine candidate antigens were found and persisted in the sera of the cured mice. These findings provide clear evidence that ALA/SFC is effective in an experimental animal model of malaria and may facilitate the development of a new class of antimalarial drug. PMID:26324278

  9. Measuring distances between TRPV1 and the plasma membrane using a noncanonical amino acid and transition metal ion FRET.

    Science.gov (United States)

    Zagotta, William N; Gordon, Moshe T; Senning, Eric N; Munari, Mika A; Gordon, Sharona E

    2016-02-01

    Despite recent advances, the structure and dynamics of membrane proteins in cell membranes remain elusive. We implemented transition metal ion fluorescence resonance energy transfer (tmFRET) to measure distances between sites on the N-terminal ankyrin repeat domains (ARDs) of the pain-transducing ion channel TRPV1 and the intracellular surface of the plasma membrane. To preserve the native context, we used unroofed cells, and to specifically label sites in TRPV1, we incorporated a fluorescent, noncanonical amino acid, L-ANAP. A metal chelating lipid was used to decorate the plasma membrane with high-density/high-affinity metal-binding sites. The fluorescence resonance energy transfer (FRET) efficiencies between L-ANAP in TRPV1 and Co(2+) bound to the plasma membrane were consistent with the arrangement of the ARDs in recent cryoelectron microscopy structures of TRPV1. No change in tmFRET was observed with the TRPV1 agonist capsaicin. These results demonstrate the power of tmFRET for measuring structure and rearrangements of membrane proteins relative to the cell membrane.

  10. Solid Polymer Electrolytes Based on Functionalized Tannic Acids from Natural Resources for All-Solid-State Lithium-Ion Batteries.

    Science.gov (United States)

    Shim, Jimin; Bae, Ki Yoon; Kim, Hee Joong; Lee, Jin Hong; Kim, Dong-Gyun; Yoon, Woo Young; Lee, Jong-Chan

    2015-12-21

    Solid polymer electrolytes (SPEs) for all-solid-state lithium-ion batteries are prepared by simple one-pot polymerization induced by ultraviolet (UV) light using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as an ion-conducting monomeric unit and tannic acid (TA)-based crosslinking agent and plasticizer. The crosslinking agent and plasticizer based on natural resources are obtained from the reaction of TA with glycidyl methacrylate and glycidyl poly(ethylene glycol), respectively. Dimensionally stable free-standing SPE having a large ionic conductivity of 5.6×10(-4)  Scm(-1) at room temperature can be obtained by the polymerization of PEGMA into P(PEGMA) with a very small amount (0.1 wt %) of the crosslinking agent and 2.0 wt % of the plasticizer. The ionic conductivity value of SPE with a crosslinked structure is one order of magnitude larger than that of linear P(PEGMA) in the waxy state.

  11. Synthesis And Characterization Of An Ion Imprinted Polymer For Cadmium Using Quinaldic Acid As Complexing Agent And Applying By Microwave

    Directory of Open Access Journals (Sweden)

    Asmawati

    2015-01-01

    Full Text Available Abstract A Cd2 Ion Imprinted Polymer Cd-IIP has been synthesized by copolymerizaton of cadmium ion quinaldic acid complexing agent 4-vynil pyridine monomer dimethyl sulfoxide solvent ethyleneglycoldimethacrylate EGDMA cross-linker and 22-azobis-isobutyronitrile AIBN initiator. Polymerization was conducted using a microwave at a temperature of 70 oC with heating times of 45 minutes. The template Cd2 was removed by leaching the template with ethanol and 4 M HCl washed by aquabidest and dried in an oven at the temperature of 60oC. The polymer particles imprinted and nonimprinted were characterized using fourir transform infrared FTIR spectroscopy scanning electron microscopy SEM and energy dispersive spectroscopy EDS. The result showed that using heating time 45 minutes at temperature 70 oC the particle morphology is viewed like as the large homogeneous. So the imprinted polymer had bands at 3483 cm-1 1726 cm-1 and 1155 cm-1 indicating the presence of OH CO and C-O respectively.

  12. Competition effect of some metal ions on the complexation of strontium with humic acid. Vol. 4

    International Nuclear Information System (INIS)

    Interaction of radioactive strontium with humic acid present in water streams is of main importance to learn about the fate of strontium in case of accidental release. In this work, formation of Sr-humate precipitate was studied radiometrically and colorimetric at different PH's. The investigations indicated that formation of the precipitated complex increases with increasing strontium concentration till saturation. The competition effect of other cations in solution such as Ca, Mg, Ba, and Ni was investigated. The humate complexes of these cations were studied colorimetric, and the competition behaviour was investigated using the radiotracer of strontium. The results indicated that presence of Ba, Mg and Ni decreases the Sr-humate complex, while increasing Ca concentration enhances precipitation of Sr with humic acid. 10 figs

  13. Optimization of L(+)-Lactic Acid Fermentation Without Neutralisation of Rhizopus Oryzae Mutant RK02 by Low-Energy Ion Implantation

    Institute of Scientific and Technical Information of China (English)

    LI Wen; YU Zengliang; WANG Tao; YANG Yingge; LIU Dan; FAN Yonghong; WANG Dongmei; YANG Qian; YAO Jianming; ZHENG Zhiming

    2008-01-01

    In order to get an industrial strain which can yield a high concentration of lactic acid for ISPR (in situ product removal), the original strain Rhizopus oryzae RE3303 was mutated by low-energy ion beam implantation. A mutant RK02 was screened, and the factors such as the substrate concentration, nitrogen source concentration, inoculum size, seed age, aeration and temperature that affect the production of lactic acid were studied in detail. Under optimal conditions, the maximum concentration of L(+)-lactic acid reached 34.85 g/L after 30 h shake-flask cultivation without adding any neutralisation (5% Glucose added), which was a 146% increase in lactic acid production after ion implantation compared with the original strain. It was also shown that RK02 can be used in ISPR to reduce the number of times of separation.

  14. Optimization of L(+)-Lactic Acid Production from Xylose with Rhizopus Oryzae Mutant RLC41-6 Breeding by Low-Energy Ion Implantation

    Science.gov (United States)

    Yang, Yingge; Fan, Yonghong; Li, Wen; Wang, Dongmei; Wu, Yuejin; Zheng, Zhiming; Yu, Zengliang

    2007-10-01

    In order to obtain an industrial strain with a higher L(+)-lactic acid yield, the strain Rhizopus oryzae PW352 was mutated by means of nitrogen ion beam implantation and the mutant strain Rhizopus oryzae RLC41-6 was obtained. An experimental finding was made in surprise that Rhizopus oryzae mutant RLC41-6 is not only an L(+)-lactic acid producer from corn starch but also an efficient producer of L(+)-lactic acid from xylose. Under optimal conditions, the production of L(+)-lactic acid from 100 g/L xylose reached 77.39 g/L after 144 h fed-batch fermentation. A high mutation rate and a wide mutation spectrum of low-energy ion implantation were observed in the experiment.

  15. Removal of lead ions from acid aqueous solutions using zeolite bearing tuff

    OpenAIRE

    Golomeova, Mirjana; Zendelska, Afrodita; Golomeov, Blagoj; Krstev, Boris; Jakupi, Shaban

    2016-01-01

    Water pollution come from a number of different sources, and pollutants are divided up into various classes, such as organic pollutants, inorganic fertilizers, metals and radioactive isotopes. Organic pollutants are susceptible to biological degradation, unlike heavy metals which are not degrade into harmless products. Heavy metals are a common pollutant found in various industrial effluents. They are often encountered in mining operations and acid mine drainage. Because heavy metals are high...

  16. Specific ionic effect for simple and rapid colorimetric sensing assays of amino acids using gold nanoparticles modified with task-specific ionic liquid.

    Science.gov (United States)

    Wu, Datong; Cai, Pengfei; Tao, Zhihao; Pan, Yuanjiang

    2016-01-01

    In this study, a novel task-specific ionic liquid functionalized gold nanoparticle (TSIL-GNP) was successfully prepared and applied in the recognition of amino acids. Particularly, the surface of GNP was modified with the ionic liquid containing carbamido and ester group via thiol, which was characterized by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The stability of this material in aqueous solution improves apparently and can remain unchanged for more than three months. The effect of pH was also discussed in this study. Attractive ionic interaction would effectively weaken intensity of the covalent coupling between the metal ion and the functional groups of amino acids. Thus, TSIL-GNP was successfully applied to recognizing serine, aspartic acid, lysine, arginine, and histidine in the presence of Cu(2+) through distinctive color changes. Suspension would be generated once a spot of cysteine was added into the GNPs solution. Results indicated that it had a good linear relationship between extinction coefficients and concentration of amino acids in a wide range of 10(-3)-10(-6) M. Moreover, the proposed strategy was successfully used to analyze the histidine in urinary samples. In brief, TSIL-GNP is a suitable substrate for discrimination of five amino acids in a rapid and simple way without sophisticated instruments.

  17. Characteristics of isothermal adsorption and desorption of aluminum ion to/from humic acids

    Institute of Scientific and Technical Information of China (English)

    WANG Qiang; WEI Shiqiang; HUANG Yuming; ZHANG Jinzhong

    2008-01-01

    The adsorption and desorption characteristics of Al3+ to/from humic acids at different pH, ionic strength, and temperature were studied by the C-25 glucosan-gel chromatography method. The results showed that the maximum adsorption amount (Qmax) and adsorption constant (k) increased, whereas, the absolute value of standard thermodynamic molar free energy change (AG0. m) decreased with the increase of pH at constant ionic strength and temperature. With ionic strength increasing from 0 to 0. 15 mol/L, Qmax and k increased and the absolute value of AG0. m decreased at constant pH and temperature. High temperature was unfavorable for the adsorption reaction, as indicated by the dramatic decrease of Qmax and the absolute value of AG0. m with an increase in temperature. The standard thermodynamic molar free energy change (AG0. m) and the standard thermodynamic enthalpy change (AH0. m) of the adsorption reaction were both negative, suggesting that adsorption reaction was spontaneous and exothermic. The desorption rate of HA-AI3+ complex accelerated with the decrease of pH, and a significant linear relationship could be obtained between pH and the desorption rates of Al3+ from humic acids. These results demonstrated that the Al3+ adsorption reaction was a "biphase" reaction, and adsorption occurred at both the interior and exterior adsorption sites of humic acids.

  18. Design of a dual-signaling sensing system for fluorescent ratiometric detection of Al3+ ion based on the inner-filter effect.

    Science.gov (United States)

    Wang, Yongxiang; Xiong, Limin; Geng, Fenghua; Zhang, Fuqiang; Xu, Maotian

    2011-11-21

    A dual-signal sensing system based on the inner-filter effect (IFE) was demonstrated, in which the combination of two signaling mechanisms allows metal binding to turn on two fluorescence emission bands, independently. A proof-of-concept fluorescent ratiometric assay for Al(3+) in pure aqueous solution is presented. The proposed assay is based on the Al(3+)-induced color and fluorescence changes of Alizarin red S (ARS) and IFE between ARS and meso-tetra(N-methyl-4-pyridyl)porphine tetratosylate salt (TMPyP). In the absence of Al(3+), the absorption spectrum of the ARS in 0.2 M HAc-NaAc buffer (pH 5.5) has a strong peak at 420 nm, significantly overlapping with the excitation of TMPyP. ARS is expected to be capable of functioning as a powerful absorber to tune the emission of TMPyP on account of the spectral overlap. Binding of Al(3+) with ARS forms a fluorometric ARS/Al(3+) complex and shifts the maximum absorbance from 420 nm to 480 nm, which overlaps negligibly with the excitation of TMPyP and turns on the proper emission spectrum for TMPyP. Under the optimum conditions, The fluorescence intensity ratio, F(585)/F(651), responds to Al(3+) over a dynamic range of 0.1-1.5 μM, with a limit of detection of 40 nM, where F(585) and F(651) are the fluorescence intensity at 585 nm and 651 nm in the absence or presence of Al(3+), respectively. Further application in Al(3+)-spiked water samples suggested a recovery between 95 and 108%. The fluorescence response is highly selective for Al(3+) over other metal ions with the addition of thiourea as the masking agent.

  19. Ion pairing with linoleic acid simultaneously enhances encapsulation efficiency and antibacterial activity of vancomycin in solid lipid nanoparticles.

    Science.gov (United States)

    Kalhapure, Rahul S; Mocktar, Chunderika; Sikwal, Dhiraj R; Sonawane, Sandeep J; Kathiravan, Muthu K; Skelton, Adam; Govender, Thirumala

    2014-05-01

    Ion pairing of a fatty acid with an antibiotic may be an effective strategy for formulation optimization of a nanoantibiotic system. The aim of this study was therefore to explore the potential of linoleic acid (LA) as an ion pairing agent to simultaneously enhance encapsulation efficiency and antibacterial activity of triethylamine neutralized vancomycin (VCM) in solid lipid nanoparticles (SLNs). The prepared VCM-LA2 conjugate was characterized by Fourier transform-infrared (FT-IR) spectroscopy, logP and binding energy calculations. The shifts in the FT-IR frequencies of COOH, NH2 and CO functionalities, an increase in logP value (1.37) and a lower interaction energy between LA and VCM (-125.54 kcal/mol) confirmed the formation of the conjugate. SLNs were prepared by a hot homogenization and ultrasonication method, and characterized for size, polydispersity index (PI), zeta potential (ZP), entrapment efficiency (%EE), surface morphology and physical stability. In vitro antibacterial activity studies against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) were conducted. Size, PI and ZP for VCM-LA2_SLNs were 102.7±1.01, 0.225±0.02 and -38.8±2.1 (mV) respectively. SLNs were also stable at 4 °C for 3 months. %EE for VCM-HCl_SLNs and VCM-LA2_SLNs were 16.81±3.64 and 70.73±5.96 respectively, indicating a significant improvement in encapsulation of the drug through ion pairing with LA. Transmission electron microscopy images showed spherical nanoparticles with sizes in the range of 95-100 nm. After 36 h, VCM-HCl showed no activity against MRSA. However, the minimum inhibitory concentration for VCM-HCl_SLNs and VCM-LA2_SLNs were 250 and 31.25 μg/ml respectively against S. aureus, while against MRSA it was 500 and 15.62 μg/ml respectively. This confirms the enhanced antibacterial activity of VCM-LA2_SLNs over VCM-HCl_SLNs. These findings therefore suggest that VCM-LA2_SLNs is a promising nanoantibiotic system for effective treatment against both

  20. Composition and stability of complexes of maleic and succinic acids with Cu2+ ions in water-ethanol solutions at 298 K

    Science.gov (United States)

    Tukumova, N. V.; Usacheva, T. R.; Thuan, Tran Thi Dieu; Sharnin, V. A.

    2014-10-01

    The composition and stability of coordination compounds of the anions of maleic (H2L) and succinic (H2Y) acids with copper(II) ions in water-ethanol solutions is studied by means of potentiometric titration at a sodium perchlorate ionic strength of 0.1 and a temperature of 298.15 K. The composition of the water-ethanol solvent was varied from 0 to 0.7 molar parts of ethanol for maleic acid and from 0 to 0.4 molar parts for succinic acid. The stability of monoligand complexes of copper ions with the anions of maleic and succinic acids grows with increase of ethanol concentration from 3.86 to 6.62 for logβCuL and from 2.98 to 6.01 for logβCuY. It is shown that a monotonic rise in stability upon an increase in the content of ethanol in solution is observed, while the values of logβCuL change more sharply. The succinic acid anion forms a stronger complex with copper ions than maleic acid anions do at an ethanol content of 0.4 molar parts. The possibility of the formation of a protonated CuHY+ particle is established.

  1. Poly (acrylic acid sodium) grafted carboxymethyl cellulose as a high performance polymer binder for silicon anode in lithium ion batteries.

    Science.gov (United States)

    Wei, Liangming; Chen, Changxin; Hou, Zhongyu; Wei, Hao

    2016-01-01

    The design of novel binder systems is required for the high capacity silicon (Si) anodes which usually undergo huge volume change during the charge/discharge cycling. Here, we introduce a poly (acrylic acid sodium)-grafted-carboxymethyl cellulose (NaPAA-g-CMC) copolymer as an excellent binder for Si anode in lithium ion batteries (LIBs). The NaPAA-g-CMC copolymer was prepared via a free radical graft polymerization method by using CMC and acrylic acid as precursors. Unlike the linear, one-dimensional binders, the NaPAA-g-CMC copolymer binder is expected to present multi-point interaction with Si surface, resulting in enhanced binding ability with Si particles as well as with the copper (Cu) current collectors, and building a stable solid electrolyte interface (SEI) layer on the Si surface. The NaPAA-g-CMC based Si anode shows much better cycle stability and higher coulombic efficiency than those made with the well-known linear polymeric binders such as CMC and NaPPA. PMID:26786315

  2. Novel polymer inclusion membranes containing T2EHDGA as carrier extractant for actinide ion uptake from acidic feeds

    Energy Technology Data Exchange (ETDEWEB)

    Mahanty, Bholanath; Das, Dillip Kumar; Behere, Praveen Gajanan; Afzal, Mohammad [Bhabha Atomic Research Centre, Tarapur, Maharashtra (India). Advanced Fuel Fabrication Facility; Mohapatra, Prasanta Kumar; Raut, Dhaval Ramakant [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Radiochemistry Div.

    2015-06-01

    Polymer inclusion membranes (PIM) containing N,N,N',N'-tetra(2-ethylhexyl) diglycolamide (T2EHDGA) were evaluated for the separation of actinide ions such as Am{sup 3+}, Pu{sup 4+}, UO{sub 2}{sup 2+} and Th{sup 4+} from acidic feeds. The PIMs were prepared using cellulose triacetate (CTA) as the polymer matrix, 2-nitrophenyloctyl ether (NPOE) as the plasticizer and T2EHDGA as the carrier extractant and the optimized membrane composition was found to be 68.4% T2EHDGA, 17.9% NPOE and 13.7% CTA which resulted in 74% Am{sup 3+} uptake at 1 M HNO{sub 3} in 2 h. The uptake studies were carried out using feed solutions containing varying concentrations of nitric acid (0.5-3.0 M) and showed the trend: Pu{sup 4+} > Am{sup 3+} > Th{sup 4+} > UO{sub 2}{sup 2+}. Quantitative stripping (> 99%) of the sorbed Am{sup 3+} was possible using a solution containing 0.01 M EDTA at pH 3.0. Reusability studies indicated deterioration of the PIM on continuous use.

  3. Rapid simultaneous analysis of 17 haloacetic acids and related halogenated water contaminants by high-performance ion chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Xue, Runmiao; Donovan, Ariel; Shi, Honglan; Yang, John; Hua, Bin; Inniss, Enos; Eichholz, Todd

    2016-09-01

    Haloacetic acids (HAAs), which include chloroacetic acids, bromoacetic acids, and emerging iodoacetic acids, are toxic water disinfection byproducts. General screening methodology is lacking for simultaneously monitoring chloro-, bromo-, and iodoacetic acids. In this study, a rapid and sensitive high-performance ion chromatography-tandem mass spectrometry method for simultaneous determination of chloro-, bromo-, and iodo- acetic acids and related halogenated contaminants including bromate, bromide, iodate, and iodide was developed to directly analyze water samples after filtration, eliminating the need for preconcentration, and chemical derivatization. The resulting method was validated in both untreated and treated water matrices including tap water, bottled water, swimming pool water, and both source water and drinking water from a drinking water treatment facility to demonstrate application potential. Satisfactory accuracies and precisions were obtained for all types of tested samples. The detection limits of this newly developed method were lower or comparable with similar techniques without the need for extensive sample treatment requirement and it includes all HAAs and other halogenated compounds. This provides a powerful methodology to water facilities for routine water quality monitoring and related water research, especially for the emerging iodoacetic acids. Graphical abstract High performance ion chromatography-tandem mass spectrometry method for detection of haloacetic acids in water.

  4. Organophosphonic acid as precursor to prepare LiFePO4/carbon nanocomposites for high-power lithium ion batteries

    International Nuclear Information System (INIS)

    Graphical abstract: LiFePO4/C nanocomposites were prepared by a quasi-sol–gel method with the use of organophosphonic acid, exhibiting improved electrochemical performance with excellent cycle stability. Display Omitted -- Highlights: •Amino tris(methylene phosphonic acid) is served as a novel precursor for LiFePO4/C. •Nano-sized and high-purity LiFePO4/C composites are obtained by a quasi-sol–gel route. •Core-shell structured LiFePO4/C nanocomposites are fabricated by further introducing sucrose. •Superior electrochemical performance is observed in the organophosphorus-synthesized LiFePO4/C. -- Abstract: Amino tris(methylene phosphonic acid) (ATMP) is selected as phosphorus and carbon co-source for the synthesis of uniformly nano-sized LiFePO4/C by a quasi-sol–gel method. This strategy using ATMP instead of conventional NH4H2PO4 supplies two advantages: firstly, ATMP in situ chelates Li+ onto its framework and subsequently binds with FeC2O4 in aqueous solution, forming a molecule-scale homogeneous precursor which can obviously improve the purity of LiFePO4. Secondly, the organic carbon contained in ATMP can form uniformly distributed conductive carbon networks among LiFePO4 particles after calcination, which improves the electrical conductivity. The resultant LiFePO4/C with 1.1 wt.% carbon achieves a higher discharge capacity than those of LiFePO4 and LiFePO4/C prepared with inorganic NH4H2PO4. Moreover, core-shell structured LiFePO4/C nanocomposites are also fabricated by further introducing sucrose into the synthesis system. The high-quality carbon shell effectively hinders the LiFePO4 particle growth and aggregation under high-temperature treatment, which further enhances the electrical conductivity and lithium-ion diffusion, resulting in the improved electrochemical performance with excellent cycle stability (the optimum discharge capacity of 158.6 mAh g−1 at 0.1 C and 138.4 mAh g−1 at 2 C). The high purity, nanosize and core-shell structure

  5. Influence of Humic Acid on Interaction of Ammonium and Potassium Ions on Clay Minerals

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wen-Zhao; CHEN Xiao-Qin; ZHOU Jian-Min; LIU Dai-Huan; WANG Huo-Yan; DU Chang-Wen

    2013-01-01

    Interaction of ammonium (NH4+) and potassium (K+) is typical in field soils.However,the effects of organic matter on interaction of NH4+ and K+ have not been thoroughly investigated.In this study,we examined the changes in major physicochemical properties of three clay minerals (kaolinite,illite,and montmorillonite) after humic acid (HA) coating and evaluated the influences of these changes on the interaction of NH4+ and K+ on clay minerals using batch experiments.After HA coating,the cation exchange capacity (CEC) and specific surface area (SSA) of montmorillonite decreased significantly,while little decrease in CEC and SSA occurred in illite and only a slight increase in CEC was found in kaolinite.Humic acid coating significantly increased cation adsorption and preference for NH4+,and this effect was more obvious on clay minerals with a lower CEC.Results of Fourier transform infrared spectrometry analysis showed that HA coating promoted the formation of H-bonds between the adsorbed NH4+ and the organo-mineral complexes.HA coating increased cation fixation capacity on montmorillonite and kaolinite,but the opposite occurred on illite.In addition,HA coating increased the competitiveness of NH4+ on fixation sites.These results showed that HA coating affected both the nature of clay mineral surfaces and the reactions of NH4+ and K+ with clay minerals,which might influence the availability of nutrient cations to plants in field soils amended with organic matter.

  6. Efficiency of Gas-Phase Ion Formation in Matrix-Assisted Laser Desorption Ionization with 2,5-Dihydroxybenzoic Acid as Matrix

    International Nuclear Information System (INIS)

    Numbers of matrix- and analyte-derived ions and their sum in matrix-assisted laser desorption ionization (MALDI) of a peptide were measured using 2,5-dihydroxybenzoic acid (DHB) as matrix. As for MALDI with α-cyano-4-hydroxy cinnamic acid as matrix, the sum was independent of the peptide concentration in the solid sample, or was the same as that of pure DHB. This suggested that the matrix ion was the primary ion and that the peptide ion was generated by matrix-to-peptide proton transfer. Experimental ionization efficiencies of 10-5-10-4 for peptides and 10-8-10-7 for matrices are far smaller than 10.3-10.1 for peptides and 10-5-10-3 for matrices speculated by Hillenkamp and Karas. Number of gas-phase ions generated by MALDI was unaffected by laser wavelength or pulse energy. This suggests that the main role of photo-absorption in MALDI is not in generating ions via a multi-photon process but in ablating materials in a solid sample to the gas phase

  7. Oxygen-18 study of the mechanism of promoter action of thiocyanate ions in the electrosynthesis of persulfuric acid and ammonium persulfate at platinum anodes

    Energy Technology Data Exchange (ETDEWEB)

    Kasatkin, E.V.; Larchenko, L.I.; Potapova, G.F.

    1987-02-01

    The authors use labelled oxygen to study the involvement of water and sulfate ions in molecular oxygen evolution during the anodic synthesis of persulfuric acid and ammonium persulfate at a platinum anode in an electrolytic cell with and without thiocyanate as a promoter for the electrocatalytic reaction.

  8. Copper(II)-rubeanic acid coprecipitation system for separation-preconcentration of trace metal ions in environmental samples for their flame atomic absorption spectrometric determinations

    International Nuclear Information System (INIS)

    A simple and facile preconcentration procedure based on the coprecipitation of trace heavy metal ions with copper(II)-rubeanic acid complex has been developed. The analytical parameters including pH, amounts of rubeanic acid, sample volume, etc. was investigated for the quantitative recoveries of Pb(II), Fe(III), Cd(II), Au(III), Pd(II) and Ni(II). No interferic effects were observed from the concomitant ions. The detection limits for analyte ions by 3 sigma were in the range of 0.14 μg/l for iron-3.4 μg/l for lead. The proposed coprecipitation method was successfully applied to water samples from Palas Lake-Kayseri, soil and sediment samples from Kayseri and Yozgat-Turkey

  9. New force field parameters for metalloproteins I: Divalent copper ion centers including three histidine residues and an oxygen-ligated amino acid residue.

    Science.gov (United States)

    Wise, Olivia; Coskuner, Orkid

    2014-06-30

    Transition metal ion complexation with proteins is ubiquitous across such diverse fields as neurodegenerative and cardiovascular diseases and cancer. In this study, the structures of divalent copper ion centers including three histidine and one oxygen-ligated amino acid residues and the relative binding affinities of the oxygen-ligated amino acid residues with these metal ion centers, which are debated in the literature, are presented. Furthermore, new force field parameters, which are currently lacking for the full-length metal-ligand moieties, are developed for metalloproteins that have these centers. These new force field parameters enable investigations of metalloproteins possessing these binding sites using molecular simulations. In addition, the impact of using the atom equivalence and inequivalence atomic partial charge calculation procedures on the simulated structures of these metallopeptides, including hydration properties, is described.

  10. Fast synthesis of platinum nanopetals and nanospheres for highly-sensitive non-enzymatic detection of glucose and selective sensing of ions

    Science.gov (United States)

    Taurino, Irene; Sanzó, Gabriella; Mazzei, Franco; Favero, Gabriele; de Micheli, Giovanni; Carrara, Sandro

    2015-10-01

    Novel methods to obtain Pt nanostructured electrodes have raised particular interest due to their high performance in electrochemistry. Several nanostructuration methods proposed in the literature use costly and bulky equipment or are time-consuming due to the numerous steps they involve. Here, Pt nanostructures were produced for the first time by one-step template-free electrodeposition on Pt bare electrodes. The change in size and shape of the nanostructures is proven to be dependent on the deposition parameters and on the ratio between sulphuric acid and chloride-complexes (i.e., hexachloroplatinate or tetrachloroplatinate). To further improve the electrochemical properties of electrodes, depositions of Pt nanostructures on previously synthesised Pt nanostructures are also performed. The electroactive surface areas exhibit a two order of magnitude improvement when Pt nanostructures with the smallest size are used. All the biosensors based on Pt nanostructures and immobilised glucose oxidase display higher sensitivity as compared to bare Pt electrodes. Pt nanostructures retained an excellent electrocatalytic activity towards the direct oxidation of glucose. Finally, the nanodeposits were proven to be an excellent solid contact for ion measurements, significantly improving the time-stability of the potential. The use of these new nanostructured coatings in electrochemical sensors opens new perspectives for multipanel monitoring of human metabolism.

  11. Determination of the extractive capacity of para-tert butyl calix[8]arene octa-phosphinoylated towards uranyl ions from an aqueous-acidic-salty medium

    International Nuclear Information System (INIS)

    The extraction properties of octa-phosphinoylated para-tert butyl calix[8]arene (prepared in the laboratory) in chloroform towards uranyl ions from an aqueous-acidic-salty medium (HNO3-3.5 NaNO3) containing uranyl nitrate salt, was investigated. Two spectroscopic techniques UV/Vis and Luminescence were used for this study. The latter permitted analyze the fluorescence from the uranyl ions influenced by the surrounding medium. Both permitted to learn about the power of this calixarene as extractant towards the mentioned ions. Its extraction ability or capability using this calixarene at 5.91 x 10-4 M towards the uranyl ions was 400% as determined by UV/Vis while fluorescence revealed 100% of uranyl ion extraction. A closed analysis of the results obtained by using these techniques revealed that the stoichiometry of the main extracted species was 1calixarene:2 uranyl ions. The loading capacity of the calixarene ligand towards the uranyl ions was also investigated using both techniques. UV/Vis resulted to be inadequate for quantifying exactly the loading capacity of the calixarene whereas luminescence was excellent indeed, using a 5.91 x 10-4 M calixarene concentration, its loading capacity was 0.157 M of free uranyl ions from 0.161 M of uranyl ions present in the aqueous-acidic-salty medium. The extracts from the ability and capacity studies were concentrated to dryness, purified and the dried extracts were analyzed by infrared and neutron activation analysis. By these techniques it was demonstrated that during the extraction of the uranyl ions by the calixarene ligand they form thermodynamically and kinetically stable complexes, since in the solid state, the 1:2, calixarene; uranyl ions stoichiometry was kept with the minimum formula: (UO2)2B8bL8(NO3)4(H2O)4CHCl3(CH3OH)3 the methanol molecules come from its purification. It is proposed that B8bL8 calixarene in chloroform medium is a good extractant for the treatment of nuclear wastes or radioactive wastes containing

  12. Evidence for differential action of indoleacetic acid upon ion fluxes in single cells of Petroselinum sativum.

    Science.gov (United States)

    Bentrup, F W; Pfrüner, H; Wagner, G

    1973-12-01

    The apparent influx of (36)Cl(-) and (86)Rb(+)/K(+) into cells from the higher plant Petroselinum sativum has been measured during the presence and absence in the culture medium of indolacetic acid (IAA) which is an essential auxin of these cells. While 10(-5) M IAA did not significantly affect the influx of (86)Rb(+)/K(+), it substantially reduced that of (36)Cl(-), i.e. by a factor 0.25 within 30 min. This differential action of IAA, which holds for a reasonable range of external pH, is assumed to bear on current hypotheses that the primary events of auxin action involve plasmalemma functions. PMID:24474466

  13. Optimization of L-lactic Acid Production of Rhizopus Oryzae Mutant RLC41-6 by Ion Beam Implantation at Low-Energy

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In order to obtain an industrial strain with a higher L(+)-lactic acid yield, the strain Rhizopus oryzae RF3608 was mutated by means of nitrogen ion beam implantation and the mutant strain RLC41-6 was isolated. Under optimal conditions the yield of L(+)-lactic acid produced in a shake-flask reached 133 g/L~137 g/L after 36 h cultivation, indicating that the It was almost a 115% increase in lactic acid production compared with the original strain RF3608.

  14. Some Lewis acid-base adducts involving boron trifluoride as electrolyte additives for lithium ion cells

    Science.gov (United States)

    Nie, Mengyun; Madec, L.; Xia, J.; Hall, D. S.; Dahn, J. R.

    2016-10-01

    Three complexes with boron trifluoride (BF3) as the Lewis acid and different Lewis bases were synthesized and used as electrolyte additives in Li[Ni1/3Mn1/3Co1/3]O2/graphite and Li[Ni0.42Mn0.42Co0.16]O2/graphite pouch cells. Lewis acid-base adducts with a boron-oxygen (Bsbnd O) bond were trimethyl phosphate boron trifluoride (TMP-BF) and triphenyl phosphine oxide boron trifluoride (TPPO-BF). These were compared to pyridine boron trifluoride (PBF) which has a boron-nitrogen (Bsbnd N) bond. The experimental results showed that cells with PBF had the least voltage drop during storage at 4.2 V, 4.4 V and 4.7 V at 40 °C and the best capacity retention during long-term cycling at 55 °C compared to cells with the other additives. Charge-hold-discharge cycling combined with simultaneous electrochemical impedance spectroscopy measurements showed that impedance growth in TMP-BF and TPPO-BF containing cells was faster than cells containing 2%PBF, suggesting that PBF is useful for impedance control at high voltages (>4.4 V). XPS analysis of the SEI films highlighted a specific reactivity of the PBF-derived SEI species that apparently hinders the degradation of both LiPF6 and solvent during formation and charge-hold-discharge cycling. The modified SEI films may explain the improved impedance, the smaller voltage drop during storage and the improved capacity retention during cycling of cells containing the PBF additive.

  15. Ion exchange studies of alpha-hydroxy carboxylic acid-lanthanide and actinide systems

    International Nuclear Information System (INIS)

    Alpha-hydroxy carboxylic acids have been used extensively for the separation of lanthanide and actinide elements with cation exchange resins. Sorption of these elements in the same solutions occurs on strong base anion-exchange resins. A study has been made by elution and equilibrium distribution techniques of the behaviour at tracer-level concentrations of these anion-exchange systems. One objective was to measure the separation factors to assess anion exchange as a possible complement to cation exchange separation. Since very little attention has been given to characterizing the complexed species present in these separation systems, a second objective was to attempt such characterization through interpretation of both cation and anion exchange data. Glycolic, lactic and alpha-hydroxy isobutyric acids were used together with radioactive tracers of Ce, Pm, Eu, Tb, Tm, Y, Cm and Cf. The elutions and equilibrium distributions were performed both at 25o C and 87o C. In all three eluants, the separation factors were smaller for the anion exchange than for the analogous cation exchange. In the glycolate solutions, the separation factors were largest and the values of the distribution coefficient Kd. indicated that these were the most stable complexes. The plots of log Kd against log anion concentration pass through a maximum and then approach a slope of -1, indicating the presence of an anionic complex MX4-. The existence of this negative complex in the solution phase was demonstrated by electromigration studies of Tm170 tracer in these solutions. At the solution concentration corresponding to the maximum Kd value, it can be shown that the predominant solution species is MX3. Approximate successive stability constants have been calculated for these systems and with these it is possible to construct diagrams showing the relative concentration of the species M+3, MX+2, MX2+, MX3 and MX4- as a function of the concentration of X-. (author)

  16. Colorimetric and bare-eye detection of alkaline earth metal ions based on the aggregation of silver nanoparticles functionalized with thioglycolic acid

    International Nuclear Information System (INIS)

    We describe a simple and rapid method for colorimetric and bare-eye detection of the alkaline earth metal ions Mg(II), Ca(II), Sr(II) and Ba(II) based on the use of silver nanoparticles (AgNPs) functionalized with thioglycolic acid (TGA). The TGA ligand was self-assembled onto the AgNPs to form a probe that undergoes a color change from yellow to orange or red on exposure to the alkaline earth ions. It is presumed that the color change is a result of the aggregation of the AgNPs caused by the interaction of the bivalent ions with the carboxy groups on the AgNPs. The color change can be used for bare-eye and colorimetric determination of the alkaline earth metal ions, for example to rapidly determine water hardness. (author)

  17. Synthesis of carbon nanoparticles from waste rice husk used for the optical sensing of metal ions%废米糠制备炭纳米颗粒及其对金属离子的光学传感性能

    Institute of Scientific and Technical Information of China (English)

    Peggy Zhen Zhen Ngu; Stephanie Pei Phing Chia; Jessica Fung Yee Fong; Sing Muk Ng

    2016-01-01

    以废米糠为原料,浓硫酸为脱水剂,通过炭化法制备出炭纳米颗粒( CNPs),探讨CNPs荧光发射特征、金属离子的淬灭效应以及作为Sn(II)离子传感材料应用。 CNPs产率最佳条件为:硫酸浓度12 mol/L、加热温度120℃及恒温时间30 min。样品在水中强蓝光的最大发射波为439 nm。通过加入金属离子,使金属离子与CNPs表面间形成复合物而淬灭荧光。 Sn(II)离子对CNPs荧光具有显著的淬灭效应。 Sn(II)离子浓度对淬灭效应符合Stern-Volmer线性关系,Sn(II)离子为6.13 mmol/L。 Sn(II)离子的检测限为18.7μmol/L。%This work reports on a synthesis of carbon nanoparticles ( CNPs) from waste rice husk by thermally-assisted carboniza-tion in the presence of concentrated sulfuric acid. The fluorescent emmision characteristics of the CNPs, their quenching effects by metal ions and their use as a sensing material for Sn( II) ions were investigated. Results indicated that the yield of CNPs was opti-mized at a sulphuric acid concentration of 12 mol/L, heating temperature of 1 200 ℃ and heating time of 30 min. The sample showed a strong blue luminescence in water with a maximum emission at 439 nm. The fluorescence can be quenched by adding vari-ous metal ions by the formation of complexes between the metal ions and surface of the CNPs. Sn( II) ions had the most significant quenching effect on the fluorescence of the CNPs, which is concentration-dependent. The concentration dependent quenching was linearized with the Stern-Volmer equation, and showed a linear response up to a Sn(II) concentration of 6. 13 mmol/L. The limit of detection for Sn(II) ions is 18. 7 μmol/L with good repeatability.

  18. Synergistic Effect of Ferulic Acid and Z-Ligustilide, Major Components of A. sinensis, on Regulating Cold-Sensing Protein TRPM8 and TPRA1 In Vitro

    Directory of Open Access Journals (Sweden)

    Yuwei Pan

    2016-01-01

    Full Text Available Angelica sinensis has been used to attenuate cold-induced cutaneous vasospasm syndrome, such as Raynaud’s disease and frostbite, in China for many years. Ferulic acid (PubChem CID: 445858 and Z-ligustilide (PubChem CID: 529865, two major components extracted from Angelica sinensis, had been reported to inhibit vasoconstriction induced by vasoconstrictors. In this study, the pharmacological interaction in regulating cold-induced vascular smooth muscle cell contraction via cold-sensing protein TRPM8 and TRPA1 was analyzed between ferulic acid and Z-ligustilide. Pharmacological interaction on inhibiting [Ca2+]i influx evoked by TRPM8 agonist WS-12 or TRPA1 agonist ASP 7663 as well as cold-induced upregulation of TRPM8 was determined using isobolographic analysis. The isobolograms demonstrated that the combinations investigated in this study produced a synergistic interaction. Combination effect of two components in inhibiting RhoA activation and phosphorylation of MLC20 induced by WS-12 or ASP 7663 was also being quantified. These findings suggest that the therapeutic effect of Angelica sinensis on cold-induced vasospasm may be partially attributed to combinational effect, via TRPM8 and TPRA1 way, between ferulic acid and Z-ligustilide.

  19. Acidosis promotes Bcl-2 family-mediated evasion of apoptosis: involvement of acid-sensing G protein-coupled receptor Gpr65 signaling to Mek/Erk.

    Science.gov (United States)

    Ryder, Christopher; McColl, Karen; Zhong, Fei; Distelhorst, Clark W

    2012-08-10

    Acidosis arises in solid and lymphoid malignancies secondary to altered nutrient supply and utilization. Tumor acidosis correlates with therapeutic resistance, although the mechanism behind this effect is not fully understood. Here we show that incubation of lymphoma cell lines in acidic conditions (pH 6.5) blocks apoptosis induced by multiple cytotoxic metabolic stresses, including deprivation of glucose or glutamine and treatment with dexamethasone. We sought to examine the role of the Bcl-2 family of apoptosis regulators in this process. Interestingly, we found that acidic culture causes elevation of both Bcl-2 and Bcl-xL, while also attenuating glutamine starvation-induced elevation of p53-up-regulated modulator of apoptosis (PUMA) and Bim. We confirmed with knockdown studies that these shifts direct survival decisions during starvation and acidosis. Importantly, the promotion of a high anti- to pro-apoptotic Bcl-2 family member ratio by acidosis renders cells exquisitely sensitive to the Bcl-2/Bcl-xL antagonist ABT-737, suggesting that acidosis causes Bcl-2 family dependence. This dependence appears to be mediated, in part, by the acid-sensing G protein-coupled receptor, GPR65, via a MEK/ERK pathway. PMID:22685289

  20. Effect of neutralized solid waste generated in lime neutralization on the ferrous ion bio-oxidation process during acid mine drainage treatment.

    Science.gov (United States)

    Liu, Fenwu; Zhou, Jun; Zhou, Lixiang; Zhang, Shasha; Liu, Lanlan; Wang, Ming

    2015-12-15

    Bio-oxidation of ferrous ions prior to lime neutralization exhibits great potential for acid mine drainage (AMD) treatment, while slow ferrous ion bio-oxidation or total iron precipitation is a bottleneck in this process. In this study, neutralized solid waste (NSW) harvested in an AMD lime neutralization procedure was added as a crystal seed in AMD for iron oxyhydroxysulfate bio-synthesis. The effect of this waste on ferrous ion oxidation efficiency, total iron precipitation efficiency, and iron oxyhydroxysulfate minerals yield during ferrous ion bio-oxidation by Acidithiobacillus ferrooxidans was investigated. Ferrous ion oxidation efficiency was greatly improved by adding NSW. After 72 h incubation, total iron precipitation efficiency in treatment with 24 g/L of NSW was 1.74-1.03 times higher than in treatment with 0-12 g/L of NSW. Compared with the conventional treatment system without added NSW, the iron oxyhydroxysulfate minerals yield was increased by approximately 21.2-80.9% when 3-24 g/L of NSW were added. Aside from NSW, jarosite and schwertmannite were the main precipitates during ferrous ion bio-oxidation with NSW addition. NSW can thus serve as the crystal seed for iron oxyhydroxysulfate mineral bio-synthesis in AMD, and improve ferrous ion oxidation and total iron precipitation efficiency significantly.