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Sample records for capacitative calcium entry

  1. Dihydropyridines as inhibitors of capacitative calcium entry in leukemic HL-60 cells

    Science.gov (United States)

    Harper, Jacquie L.; Camerini-Otero, Carol S.; Li, An-Hu; Kim, Soon-Ai; Jacobson, Kenneth A.; Daly, John W.

    2016-01-01

    A series of 1,4-dihydropyridines (DHPs) were investigated as inhibitors of capacitative calcium influx through store-operated calcium (SOC) channels. Such channels activate after ATP-elicited release of inositol trisphosphate (IP3)-sensitive calcium stores in leukemia HL-60 cells. The most potent DHPs were those containing a 4-phenyl group with an electron-withdrawing substituent, such as m- or p-nitro- or m-trifluoromethyl (IC50 values: 3–6 μM). Benzyl esters, corresponding to the usual ethyl/methyl esters of the DHPs developed as L-type calcium channel blockers, retained potency at SOC channels, as did N-substituted DHPs. N-Methylation reduced by orders of magnitude the potency at L-type channels resulting in DHPs nearly equipotent at SOC and L-type channels. DHPs with N-ethyl, N-allyl, and N-propargyl groups also had similar potencies at SOC and L-type channels. Replacement of the usual 6-methyl group of DHPs with larger groups, such as cyclobutyl or phenyl, eliminated activity at the SOC channels; such DHPs instead elicited formation of inositol phosphates and release of IP3-sensitive calcium stores. Other DHPs also caused a release of calcium stores, but usually at significantly higher concentrations than those required for the inhibition of capacitative calcium influx. Certain DHPs appeared to cause an incomplete blockade of SOC channel-dependent elevations of calcium, suggesting the presence of more than one class of such channels in HL-60 cells. N-Methylnitrendipine (IC50 2.6 μM, MRS 1844) and N-propargylnifrendipine (IC50 1.7 μM, MRS 1845) represent possible lead compounds for the development of selective SOC channel inhibitors. PMID:12527326

  2. Mechanism of store-operated calcium entry

    Indian Academy of Sciences (India)

    Devkanya Dutta

    2000-12-01

    Activation of receptors coupled to the phospholipase C/IP3 signalling pathway results in a rapid release of calcium from its intracellular stores, eventually leading to depletion of these stores. Calcium store depletion triggers an influx of extracellular calcium across the plasma membrane, a mechanism known as the store-operated calcium entry or capacitative calcium entry. Capacitative calcium current plays a key role in replenishing calcium stores and activating various physiological processes. Despite considerable efforts, very little is known about the molecular nature of the capacitative channel and the signalling pathway that activates it. This review summarizes our current knowledge about store operated calcium entry and suggests possible hypotheses for its mode of activation.

  3. Arachidonic acid mediates non-capacitative calcium entry evoked by CB1-cannabinoid receptor activation in DDT1 MF-2 smooth muscle cells

    NARCIS (Netherlands)

    Demuth, D.G.; Gkoumassi, Effimia; Droge, M.J.; Dekkers, B.G.J.; Esselink, H.J.; van Ree, Rutger; Parsons, M.E.; Zaagsma, Hans; Molleman, A; Nelemans, Herman

    2005-01-01

    Cannabinoid CB1-receptor stimulation in DDT1 MF-2 smooth muscle cells induces a rise in [Ca2+](i), which is dependent on extracellular Ca2+ and modulated by thapsigargin-sensitive stores, suggesting capacitative Ca2+ entry (CCE), and by MAP kinase. Non-capacitative Ca2+ entry (NCCE) stimulated by ar

  4. Calcium paradox and calcium entry blockers

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Slade, A.M.; Nayler, W.G.; Meijler, F.L.

    1984-01-01

    Reperfusion of isolated hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). This phenomenon is characterized by an excessive influx of calcium into the cells, the rapid onset of myocardial contracture, exhausti

  5. INHIBITING MAP KINASE ACTIVITY PREVENTS CALCIUM TRANSIENTS AND MITOSIS ENTRY IN EARLY SEA URCHIN EMBRYOS

    OpenAIRE

    Philipova, Rada; Larman, Mark G.; Leckie, Calum P.; Harrison, Patrick K.; Groigno, Laurence; Whitaker, Michael

    2005-01-01

    A transient calcium increase triggers nuclear envelope breakdown (mitosis entry) in sea urchin embryos. Cdk1/cyclin B kinase activation is also known to be required for mitosis entry. More recently MAP kinase activity has also been shown to increase during mitosis. In sea urchin embryos both kinases show a similar activation profile, peaking at the time of mitosis entry.

  6. T-Type Calcium Channel: A Privileged Gate for Calcium Entry and Control of Adrenal Steroidogenesis.

    Science.gov (United States)

    Rossier, Michel F

    2016-01-01

    have been described yet to affect cortisol secretion or to be linked to the development of Cushing syndrome, but several evidences suggest that the function of T channels is also crucial in fasciculata cells. Putative molecular mechanisms and cellular structural organization making T channels a privileged entry for the "steroidogenic calcium" are also discussed. PMID:27242667

  7. T-type calcium channel: a privileged gate for calcium entry and control of adrenal steroidogenesis

    Directory of Open Access Journals (Sweden)

    Michel Florian Rossier

    2016-05-01

    -type channels have been described yet to affect cortisol secretion or to be linked to the development of Cushing syndrome, but several evidences suggest that the function of T channels is also crucial in fasciculata cells. Putative molecular mechanisms and cellular structural organization making T channels a privileged entry for the steroidogenic calcium are also discussed.

  8. Nitric oxide inhibits capacitative Ca2+ entry by suppression of mitochondrial Ca2+ handling

    Science.gov (United States)

    Thyagarajan, Baskaran; Malli, Roland; Schmidt, Kurt; Graier, Wolfgang F; Groschner, Klaus

    2002-01-01

    Nitric oxide (NO) is a key modulator of cellular Ca2+ signalling and a determinant of mitochondrial function. Here, we demonstrate that NO governs capacitative Ca2+ entry (CCE) into HEK293 cells by impairment of mitochondrial Ca2+ handling. Authentic NO as well as the NO donors 1-[2-(carboxylato)pyrrolidin-1-yl]diazem-1-ium-1,2-diolate (ProliNO) and 2-(N,N-diethylamino)-diazenolate-2-oxide (DEANO) suppressed CCE activated by thapsigargin (TG)-induced store depletion. Threshold concentrations for inhibition of CCE by ProliNO and DEANO were 0.3 and 1 μM, respectively. NO-induced inhibition of CCE was not mimicked by peroxynitrite (100 μM), the peroxynitrite donor 3-morpholino-sydnonimine (SIN-1, 100 μM) or 8-bromoguanosine 3′,5′-cyclic monophosphate (8-BrcGMP, 1 mM). In addition, the guanylyl cyclase inhibitor 1H-[1,2,4] oxadiazole[4,3-a] quinoxalin-1-one (ODQ, 30 μM) failed to antagonize the inhibitory action of NO on CCE. DEANO (1–10 μM) suppressed mitochondrial respiration as evident from inhibition of cellular oxygen consumption. Experiments using fluorescent dyes to monitor mitochondrial membrane potential and mitochondrial Ca2+ levels, respectively, indicated that DEANO (10 μM) depolarized mitochondria and suppressed mitochondrial Ca2+ sequestration. The inhibitory effect of DEANO on Ca2+ uptake into mitochondria was confirmed by recording mitochondrial Ca2+ during agonist stimulation in HEK293 cells expressing ratiometric-pericam in mitochondria. DEANO (10 μM) failed to inhibit Ba2+ entry into TG-stimulated cells when extracellular Ca2+ was buffered below 1 μM, while clear inhibition of Ba2+ entry into store depleted cells was observed when extracellular Ca2+ levels were above 10 μM. Moreover, buffering of intracellular Ca2+ by use of N,N′-[1,2-ethanediylbis(oxy-2,1-phenylene)] bis [N-[25-[(acetyloxy) methoxy]-2-oxoethyl

  9. Outward potassium current oscillations in macrophage polykaryons: extracellular calcium entry and calcium-induced calcium release

    Directory of Open Access Journals (Sweden)

    Saraiva R.M.

    1997-01-01

    Full Text Available Outward current oscillations associated with transient membrane hyperpolarizations were induced in murine macrophage polykaryons by membrane depolarization in the absence of external Na+. Oscillations corresponded to a cyclic activation of Ca2+-dependent K+ currents (IKCa probably correlated with variations in intracellular Ca2+ concentration. Addition of external Na+ (8 mM immediately abolished the outward current oscillations, suggesting that the absence of the cation is necessary not only for their induction but also for their maintenance. Oscillations were completely blocked by nisoldipine. Ruthenium red and ryanodine reduced the number of outward current cycles in each episode, whereas quercetin prolonged the hyperpolarization 2- to 15-fold. Neither low molecular weight heparin nor the absence of a Na+ gradient across the membrane had any influence on oscillations. The evidence suggests that Ca2+ entry through a pathway sensitive to Ca2+ channel blockers is elicited by membrane depolarization in Na+-free medium and is essential to initiate oscillations, which are also dependent on the cyclic release of Ca2+ from intracellular Ca2+-sensitive stores; Ca2+ ATPase acts by reducing intracellular Ca2+, thus allowing slow deactivation of IKCa. Evidence is presented that neither a Na+/Ca2+ antiporter nor Ca2+ release from IP3-sensitive Ca2+ stores participate directly in the mechanism of oscillation

  10. Molecular modulators of store-operated calcium entry.

    Science.gov (United States)

    Lopez, Jose J; Albarran, Letizia; Gómez, Luis J; Smani, Tarik; Salido, Gines M; Rosado, Juan A

    2016-08-01

    Three decades ago, store-operated Ca(2+) entry (SOCE) was identified as a unique mechanism for Ca(2+) entry through plasma membrane (PM) Ca(2+)-permeable channels modulated by the intracellular Ca(2+) stores, mainly the endoplasmic reticulum (ER). Extensive analysis of the communication between the ER and the PM leads to the identification of the protein STIM1 as the ER-Ca(2+) sensor that gates the Ca(2+) channels in the PM. Further analysis on the biophysical, electrophysiological and biochemical properties of STIM1-dependent Ca(2+) channels has revealed the presence of a highly Ca(2+)-selective channel termed Ca(2+) release-activated Ca(2+) channel (CRAC), consisting of Orai1 subunits, and non-selective cation channels named store-operated channels (SOC), including both Orai1 and TRPC channel subunits. Since the identification of the key elements of CRAC and SOC channels a number of intracellular modulators have been reported to play essential roles in the stabilization of STIM-Orai interactions, collaboration with STIM1 conformational changes or mediating slow Ca(2+)-dependent inactivation. Here, we review our current understanding of some of the key modulators of STIM1-Orai1 interaction, including the proteins CRACR2A, STIMATE, SARAF, septins, golli and ORMDL3. PMID:27130253

  11. Deciphering the plasma membrane hallmarks of apoptotic cells: Phosphatidylserine transverse redistribution and calcium entry

    Directory of Open Access Journals (Sweden)

    Martínez M Carmen

    2001-10-01

    Full Text Available Abstract Background During apoptosis, Ca2+-dependent events participate in the regulation of intracellular and morphological changes including phosphatidylserine exposure in the exoplasmic leaflet of the cell plasma membrane. The occurrence of phosphatidylserine at the surface of specialized cells, such as platelets, is also essential for the assembly of the enzyme complexes of the blood coagulation cascade, as demonstrated by hemorrhages in Scott syndrome, an extremely rare genetic deficiency of phosphatidylserine externalization, without other apparent pathophysiologic consequences. We have recently reported a reduced capacitative Ca2+ entry in Scott cells which may be part of the Scott phenotype. Results Taking advantage of these mutant lymphoblastoid B cells, we have studied the relationship between this mode of Ca2+ entry and phosphatidylserine redistribution during apoptosis. Ca2+ ionophore induced apoptosis in Scott but not in control cells. However, inhibition of store-operated Ca2+ channels led to caspase-independent DNA fragmentation and decrease of mitochondrial membrane potential in both control and Scott cells. Inhibition of cytochrome P450 also reduced capacitative Ca2+ entry and induced apoptosis at comparable extents in control and Scott cells. During the apoptotic process, both control and more markedly Scott cells externalized phosphatidylserine, but in the latter, this membrane feature was however dissociated from several other intracellular changes. Conclusions The present results suggest that different mechanisms account for phosphatidylserine transmembrane migration in cells undergoing stimulation and programmed death. These observations testify to the plasticity of the plasma membrane remodeling process, allowing normal apoptosis even when less fundamental functions are defective.

  12. Progesterone suppressed vasoconstriction in human umbilical vein via reducing calcium entry.

    Science.gov (United States)

    He, Yun; Gao, Qinqin; Han, Bing; Zhu, Xiaolin; Zhu, Di; Tao, Jianying; Chen, Jie; Xu, Zhice

    2016-04-01

    The aim of this study was to evaluate the actions of progesterone on human umbilical vein (HUV) from normal pregnancies and the possible underlying mechanisms involved. HUV rings were suspended in organ baths and exposed to progesterone followed by phenylephrine (PE) or serotonin (5-HT). Progesterone suppressed PE- or 5-HT-induced vasoconstriction in HUV rings. The inhibitory effect induced by progesterone was not influenced by nitric oxide syntheses inhibitor, prostaglandins syntheses blocker, the integrity of endothelium, selective progesterone receptor or potassium channel antagonists. Further testing showed that progesterone and nifedipine (a blocker for L-type calcium channels) produced similar inhibitory effects on PE-, 5-HT-, Bay-k8644-, KCl-induced vasoconstriction in Krebs solution as well as CaCl2-induced vasoconstriction in Ca(2+)-free Krebs solution. But the inhibitory effect of mibefradil (mibe, a blocker for L-type (CaV1.2) and T-type calcium channels (CaV3.2)) on PE-, 5-HT-induced vasoconstriction was significantly greater than progesterone or nifedipine in Krebs solution. Furthermore, progesterone did not affect the vasoconstriction caused by PE, 5-HT, or caffeine in Ca(2+)-free Krebs solution. In addition, incubation HUV with progesterone did not change CaV1.2 and progesterone receptor (PR) expressions. The results gained demonstrated that progesterone could suppress multiple agonist-induced vasoconstrictions in HUV, mainly due to a reduction of calcium entry through L-type calcium channels, not endothelium-dependent vascular relaxation pathways, potassium channels, or Ca(2+) release from intracellular stores, providing new information important to further understanding the contribution of progesterone in the regulation of the placental-fetal circulation. PMID:26875775

  13. Role of AQP2 in activation of calcium entry by hypotonicity: implications in cell volume regulation.

    Science.gov (United States)

    Galizia, L; Flamenco, M P; Rivarola, V; Capurro, C; Ford, P

    2008-03-01

    We previously reported in a rat cortical collecting duct cell line (RCCD(1)) that the presence of aquaporin 2 (AQP2) in the cell membrane is critical for the rapid activation of regulatory volume decrease mechanisms (RVD) (Ford et al. Biol Cell 97: 687-697, 2005). The aim of our present work was to investigate the signaling pathway that links AQP2 to this rapid RVD activation. Since it has been previously described that hypotonic conditions induce intracellular calcium ([Ca(2+)](i)) increases in different cell types, we tested the hypothesis that AQP2 could have a role in activation of calcium entry by hypotonicity and its implication in cell volume regulation. Using a fluorescent probe technique, we studied [Ca(2+)](i) and cell volume changes in response to a hypotonic shock in WT-RCCD(1) (not expressing aquaporins) and in AQP2-RCCD(1) (transfected with AQP2) cells. We found that after a hypotonic shock only AQP2-RCCD(1) cells exhibit a substantial increase in [Ca(2+)](i). This [Ca(2+)](i) increase is strongly dependent on extracellular Ca(2+) and is partially inhibited by thapsigargin (1 muM) indicating that the rise in [Ca(2+)](i) reflects both influx from the extracellular medium and release from intracellular stores. Exposure of AQP2-RCCD(1) cells to 100 muM gadolinium reduced the increase in [Ca(2+)](i) suggesting the involvement of a mechanosensitive calcium channel. Furthermore, exposure of cells to all of the above described conditions impaired rapid RVD. We conclude that the expression of AQP2 in the cell membrane is critical to produce the increase in [Ca(2+)](i) which is necessary to activate RVD in RCCD(1) cells. PMID:18094031

  14. Defective Store-Operated Calcium Entry Causes Partial Nephrogenic Diabetes Insipidus.

    Science.gov (United States)

    Mamenko, Mykola; Dhande, Isha; Tomilin, Viktor; Zaika, Oleg; Boukelmoune, Nabila; Zhu, Yaming; Gonzalez-Garay, Manuel L; Pochynyuk, Oleh; Doris, Peter A

    2016-07-01

    Store-operated calcium entry (SOCE) is the mechanism by which extracellular signals elicit prolonged intracellular calcium elevation to drive changes in fundamental cellular processes. Here, we investigated the role of SOCE in the regulation of renal water reabsorption, using the inbred rat strain SHR-A3 as an animal model with disrupted SOCE. We found that SHR-A3, but not SHR-B2, have a novel truncating mutation in the gene encoding stromal interaction molecule 1 (STIM1), the endoplasmic reticulum calcium (Ca(2+)) sensor that triggers SOCE. Balance studies revealed increased urine volume, hypertonic plasma, polydipsia, and impaired urinary concentrating ability accompanied by elevated circulating arginine vasopressin (AVP) levels in SHR-A3 compared with SHR-B2. Isolated, split-open collecting ducts (CD) from SHR-A3 displayed decreased basal intracellular Ca(2+) levels and a major defect in SOCE. Consequently, AVP failed to induce the sustained intracellular Ca(2+) mobilization that requires SOCE in CD cells from SHR-A3. This effect decreased the abundance of aquaporin 2 and enhanced its intracellular retention, suggesting impaired sensitivity of the CD to AVP in SHR-A3. Stim1 knockdown in cultured mpkCCDc14 cells reduced SOCE and basal intracellular Ca(2+) levels and prevented AVP-induced translocation of aquaporin 2, further suggesting the effects in SHR-A3 result from the expression of truncated STIM1. Overall, these results identify a novel mechanism of nephrogenic diabetes insipidus and uncover a role of SOCE in renal water handling. PMID:26574044

  15. Defective Store-Operated Calcium Entry Causes Partial Nephrogenic Diabetes Insipidus.

    Science.gov (United States)

    Mamenko, Mykola; Dhande, Isha; Tomilin, Viktor; Zaika, Oleg; Boukelmoune, Nabila; Zhu, Yaming; Gonzalez-Garay, Manuel L; Pochynyuk, Oleh; Doris, Peter A

    2016-07-01

    Store-operated calcium entry (SOCE) is the mechanism by which extracellular signals elicit prolonged intracellular calcium elevation to drive changes in fundamental cellular processes. Here, we investigated the role of SOCE in the regulation of renal water reabsorption, using the inbred rat strain SHR-A3 as an animal model with disrupted SOCE. We found that SHR-A3, but not SHR-B2, have a novel truncating mutation in the gene encoding stromal interaction molecule 1 (STIM1), the endoplasmic reticulum calcium (Ca(2+)) sensor that triggers SOCE. Balance studies revealed increased urine volume, hypertonic plasma, polydipsia, and impaired urinary concentrating ability accompanied by elevated circulating arginine vasopressin (AVP) levels in SHR-A3 compared with SHR-B2. Isolated, split-open collecting ducts (CD) from SHR-A3 displayed decreased basal intracellular Ca(2+) levels and a major defect in SOCE. Consequently, AVP failed to induce the sustained intracellular Ca(2+) mobilization that requires SOCE in CD cells from SHR-A3. This effect decreased the abundance of aquaporin 2 and enhanced its intracellular retention, suggesting impaired sensitivity of the CD to AVP in SHR-A3. Stim1 knockdown in cultured mpkCCDc14 cells reduced SOCE and basal intracellular Ca(2+) levels and prevented AVP-induced translocation of aquaporin 2, further suggesting the effects in SHR-A3 result from the expression of truncated STIM1. Overall, these results identify a novel mechanism of nephrogenic diabetes insipidus and uncover a role of SOCE in renal water handling.

  16. Dystrophin/α1-syntrophin scaffold regulated PLC/PKC-dependent store-operated calcium entry in myotubes.

    Science.gov (United States)

    Sabourin, Jessica; Harisseh, Rania; Harnois, Thomas; Magaud, Christophe; Bourmeyster, Nicolas; Déliot, Nadine; Constantin, Bruno

    2012-12-01

    In skeletal muscles from patient suffering of Duchenne Muscular Dystrophy and from mdx mice, the absence of the cytoskeleton protein dystrophin has been shown to be essential for maintaining a normal calcium influx. We showed that a TRPC store-dependent cation influx is increased by loss of dystrophin or a scaffolding protein α1-syntrophin, however the mechanisms of this calcium mishandling are incompletely understood. First of all, we confirmed that TRPC1 but also STIM1 and Orai1 are supporting the store-operated cation entry which is enhanced in dystrophin-deficient myotubes. Next, we demonstrated that inhibition of PLC or PKC in dystrophin-deficient myotubes restores elevated cation entry to normal levels similarly to enforced minidystrophin expression. In addition, silencing α1-syntrophin also increased cation influx in a PLC/PKC dependent pathway. We also showed that α1-syntrophin and PLCβ are part of a same protein complex reinforcing the idea of their inter-relation in calcium influx regulation. This elevated cation entry was decreased to normal levels by chelating intracellular free calcium with BAPTA-AM. Double treatments with BAPTA-AM and PLC or PKC inhibitors suggested that the elevation of cation influx by PLC/PKC pathway is dependent on cytosolic calcium. All these results demonstrate an involvement in dystrophin-deficient myotubes of a specific calcium/PKC/PLC pathway in elevation of store-operated cation influx supported by the STIM1/Orai1/TRPC1 proteins, which is normally regulated by the α1-syntrophin/dystrophin scaffold.

  17. Two chromogranin a-derived peptides induce calcium entry in human neutrophils by calmodulin-regulated calcium independent phospholipase A2.

    Directory of Open Access Journals (Sweden)

    Dan Zhang

    Full Text Available BACKGROUND: Antimicrobial peptides derived from the natural processing of chromogranin A (CgA are co-secreted with catecholamines upon stimulation of chromaffin cells. Since PMNs play a central role in innate immunity, we examine responses by PMNs following stimulation by two antimicrobial CgA-derived peptides. METHODOLOGY/PRINCIPAL FINDINGS: PMNs were treated with different concentrations of CgA-derived peptides in presence of several drugs. Calcium mobilization was observed by using flow cytometry and calcium imaging experiments. Immunocytochemistry and confocal microscopy have shown the intracellular localization of the peptides. The calmodulin-binding and iPLA2 activating properties of the peptides were shown by Surface Plasmon Resonance and iPLA2 activity assays. Finally, a proteomic analysis of the material released after PMNs treatment with CgA-derived peptides was performed by using HPLC and Nano-LC MS-MS. By using flow cytometry we first observed that after 15 s, in presence of extracellular calcium, Chromofungin (CHR or Catestatin (CAT induce a concentration-dependent transient increase of intracellular calcium. In contrast, in absence of extra cellular calcium the peptides are unable to induce calcium depletion from the stores after 10 minutes exposure. Treatment with 2-APB (2-aminoethoxydiphenyl borate, a store operated channels (SOCs blocker, inhibits completely the calcium entry, as shown by calcium imaging. We also showed that they activate iPLA2 as the two CaM-binding factors (W7 and CMZ and that the two sequences can be aligned with the two CaM-binding domains reported for iPLA2. We finally analyzed by HPLC and Nano-LC MS-MS the material released by PMNs following stimulation by CHR and CAT. We characterized several factors important for inflammation and innate immunity. CONCLUSIONS/SIGNIFICANCE: For the first time, we demonstrate that CHR and CAT, penetrate into PMNs, inducing extracellular calcium entry by a CaM-regulated i

  18. Inhibition of Store-Operated Calcium Entry Protects Endothelial Progenitor Cells from H2O2-Induced Apoptosis.

    Science.gov (United States)

    Wang, Yan-Wei; Zhang, Ji-Hang; Yu, Yang; Yu, Jie; Huang, Lan

    2016-07-01

    Store-operated calcium entry (SOCE), a major mode of extracellular calcium entry, plays roles in a variety of cell activities. Accumulating evidence indicates that the intracellular calcium ion concentration and calcium signaling are critical for the responses induced by oxidative stress. The present study was designed to investigate the potential effect of SOCE inhibition on H2O2-induced apoptosis in endothelial progenitor cells (EPCs), which are the predominant cells involved in endothelial repair. The results showed that H2O2-induced EPC apoptosis was reversed by SOCE inhibition induced either using the SOCE antagonist ML-9 or via silencing of stromal interaction molecule 1 (STIM1), a component of SOCE. Furthermore, SOCE inhibition repressed the increases in intracellular reactive oxygen species (ROS) levels and endoplasmic reticulum (ER) stress and ameliorated the mitochondrial dysfunction caused by H2O2. Our findings provide evidence that SOCE inhibition exerts a protective effect on EPCs in response to oxidative stress induced by H2O2 and may serve as a potential therapeutic strategy against vascular endothelial injury. PMID:27169819

  19. Chlorpromazine inhibits store-operated calcium entry and subsequent noradrenaline secretion in PC12 cells

    OpenAIRE

    Choi, Se-Young; Kim, Yong-Hyun; Lee, Yong-kyu; Kim, Kyong-Tai

    2001-01-01

    The effect of chlorpromazine on the store-operated Ca2+ entry activated via the phospholipase C signalling pathway was investigated in PC12 cells.Chlorpromazine inhibited the sustained increase after the initial peak in the intracellular Ca2+ concentration produced by bradykinin while having no effect on the initial transient response. The inhibition was lowered by the removal of extracellular free Ca2+. However, chlorpromazine did not inhibit bradykinin-induced inositol 1,4,5-trisphosphate p...

  20. Different sensitivities for four calcium entry blockers of serotonin-, but not K+-induced contractions of isolated jugular vein and aorta of the rat

    NARCIS (Netherlands)

    Gouw, M.A.M.; Wilffert, B.; Van Zwieten, P.A.

    1989-01-01

    We investigated the inhibitory effect of the calcium entry blockers (CEBs) nifedipine, diltiazem, flunarizine and gallopamil on K+- and serotonin (5-HT)-induced contractions of the rat jugular vein and aorta in vitro. In both tissues all four CEBs inhibited K+-induced contractions concentration-depe

  1. Different effects of R 56865 and calcium entry blockers on K+- and noradrenaline-induced contractions and45Ca uptake in rat aorta

    NARCIS (Netherlands)

    Koch, P.; Wilhelm, D.; Wermelskirchen, D.; Nebel, U.; Wilffert, B.; Peters, Thies

    1988-01-01

    The effects of R 56865, nifedipine, verapamil, diltiazem and flunarizine on K+- and NA-induced contractions and K+-induced45Ca uptake were compared in the isolated rat aorta. The calcium entry blockers concentration dependently inhibited the K+-induced contraction and45Ca uptake over the same dose-r

  2. Complex actions of ionomycin in cultured cerebellar astrocytes affecting both calcium-induced calcium release and store-operated calcium entry

    DEFF Research Database (Denmark)

    Müller, Margit S; Obel, Linea Lykke Frimodt; Waagepetersen, Helle S;

    2013-01-01

    The polyether antibiotic ionomycin is a common research tool employed to raise cytosolic Ca(2+) in almost any cell type. Although initially thought to directly cause physicochemical translocation of extracellular Ca(2+) into the cytosol, a number of studies have demonstrated that the mechanism of......(2+), consisting of an initial peak and a subsequent sustained plateau. The response was dependent on concentration and exposure time. While the plateau phase was abolished in the absence of extracellular Ca(2+), the peak phase persisted. The peak amplitude could be lowered significantly...... by application of dantrolene, demonstrating involvement of Ca(2+)-induced Ca(2+)-release (CICR). The plateau phase was markedly reduced when store-operated Ca(2+)-entry (SOCE) was blocked with 2-aminoethoxydiphenyl borate. Our results show that ionomycin directly affects internal Ca(2+) stores in astrocytes...

  3. Allergens stimulate store-operated calcium entry and cytokine production in airway epithelial cells.

    Science.gov (United States)

    Jairaman, Amit; Maguire, Chelsea H; Schleimer, Robert P; Prakriya, Murali

    2016-01-01

    Aberrant immune responses to environmental allergens including insect allergens from house dust mites and cockroaches contribute to allergic inflammatory diseases such as asthma in susceptible individuals. Airway epithelial cells (AECs) play a critical role in this process by sensing the proteolytic activity of allergens via protease-activated receptors (PAR2) to initiate inflammatory and immune responses in the airway. Elevation of cytosolic Ca(2+) is an important signaling event in this process, yet the fundamental mechanism by which allergens induce Ca(2+) elevations in AECs remains poorly understood. Here we find that extracts from dust mite and cockroach induce sustained Ca(2+) elevations in AECs through the activation of Ca(2+) release-activated Ca(2+) (CRAC) channels encoded by Orai1 and STIM1. CRAC channel activation occurs, at least in part, through allergen mediated stimulation of PAR2 receptors. The ensuing Ca(2+) entry then activates NFAT/calcineurin signaling to induce transcriptional production of the proinflammatory cytokines IL-6 and IL-8. These findings highlight a key role for CRAC channels as regulators of allergen induced inflammatory responses in the airway. PMID:27604412

  4. Blockade of store-operated calcium entry alleviates ethanol-induced hepatotoxicity via inhibiting apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Ruibing [Department of Hepatology and Gastroenterology, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012 (China); Yan, Lihui [Shandong Normal University, Jinan, Shandong Province 250012 (China); Luo, Zheng; Guo, Xiaolan [Department of Hepatology and Gastroenterology, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012 (China); Yan, Ming, E-mail: ymylh@163.com [Department of Hepatology and Gastroenterology, Qilu Hospital of Shandong University, Jinan, Shandong Province 250012 (China)

    2015-08-15

    Extracellular Ca{sup 2+} influx has been suggested to play a role in ethanol-induced hepatocyte apoptosis and necrosis. Previous studies indicated that store-operated Ca{sup 2+} entry (SOCE) was involved in liver injury induced by ethanol in HepG2 cells. However, the mechanisms underlying liver injury caused by SOCE remain unclear. We aimed to investigate the effects and mechanism of SOCE inhibition on liver injury induced by ethanol in BRL cells and Sprague–Dawley rats. Our data demonstrated that ethanol (0–400 mM) dose-dependently increased hepatocyte injury and 100 mM ethanol significantly upregulated the mRNA and protein expression of SOC for at least 72 h in BRL cells. Blockade of SOCE by pharmacological inhibitors and sh-RNA knockdown of STIM1 and Orai1 attenuated intracellular Ca{sup 2+} overload, restored the mitochondrial membrane potential (MMP), decreased cytochrome C release and inhibited ethanol-induced apoptosis. STIM1 and Orai1 expression was greater in ethanol-treated than control rats, and the SOCE inhibitor corosolic acid ameliorated the histopathological findings and alanine transaminase and aspartate transaminase activity as well as decreased cytochrome C release and inhibited alcohol-induced cell apoptosis. These findings suggest that SOCE blockade could alleviate alcohol-induced hepatotoxicity via inhibiting apoptosis. SOCE might be a useful therapeutic target in alcoholic liver diseases. - Highlights: • Blockade of SOCE alleviated overload of Ca{sup 2+} and hepatotoxicity after ethanol application. • Blockade of SOCE inhibited mitochondrial apoptosis after ethanol application. • SOCE might be a useful therapeutic target in alcoholic liver diseases.

  5. Modeled microgravity suppressed invasion and migration of human glioblastoma U87 cells through downregulating store-operated calcium entry

    International Nuclear Information System (INIS)

    Glioblastoma is the most common brain tumor and is characterized with robust invasion and migration potential resulting in poor prognosis. Previous investigations have demonstrated that modeled microgravity (MMG) could decline the cell proliferation and attenuate the metastasis potential in several cell lines. In this study, we studied the effects of MMG on the invasion and migration potentials of glioblastoma in human glioblastoma U87 cells. We found that MMG stimulation significantly attenuated the invasion and migration potentials, decreased thapsigargin (TG) induced store-operated calcium entry (SOCE) and downregulated the expression of Orai1 in U87 cells. Inhibition of SOCE by 2-APB or stromal interaction molecule 1 (STIM1) downregulation both mimicked the effects of MMG on the invasion and migration potentials in U87 cells. Furthermore, upregulation of Orai1 significantly weakened the effects of MMG on the invasion and migration potentials in U87 cells. Therefore, these findings indicated that MMG stimulation inhibited the invasion and migration potentials of U87 cells by downregulating the expression of Orai1 and sequentially decreasing the SOCE, suggesting that MMG might be a new potential therapeutic strategy in glioblastoma treatment in the future. - Highlights: • Modeled microgravity (MMG) suppressed migration and invasion in U87 cells. • MMG downregulated the SOCE and the expression of Orai1. • SOCE inhibition mimicked the effects of MMG on migration and invasion potentials. • Restoration of SOCE diminished the effects of MMG on migration and invasion

  6. Modeled microgravity suppressed invasion and migration of human glioblastoma U87 cells through downregulating store-operated calcium entry

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zi-xuan [Department of Traditional Chinese Medicine, Xijing Hospital, Fourth Military Medical University, Xi' an, 710032 (China); Rao, Wei [Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi' an, 710032 (China); Wang, Huan [Department of Dermatology, Tangdu Hospital, Fourth Military Medical University, Xi' an, 710032 (China); Wang, Nan-ding [Department of Cardiology, Xi' an Traditional Chinese Medicine Hospital, Xi' an, 710032 (China); Si, Jing-Wen; Zhao, Jiao; Li, Jun-chang [Department of Traditional Chinese Medicine, Xijing Hospital, Fourth Military Medical University, Xi' an, 710032 (China); Wang, Zong-ren, E-mail: zongren@fmmu.edu.cn [Department of Traditional Chinese Medicine, Xijing Hospital, Fourth Military Medical University, Xi' an, 710032 (China)

    2015-02-13

    Glioblastoma is the most common brain tumor and is characterized with robust invasion and migration potential resulting in poor prognosis. Previous investigations have demonstrated that modeled microgravity (MMG) could decline the cell proliferation and attenuate the metastasis potential in several cell lines. In this study, we studied the effects of MMG on the invasion and migration potentials of glioblastoma in human glioblastoma U87 cells. We found that MMG stimulation significantly attenuated the invasion and migration potentials, decreased thapsigargin (TG) induced store-operated calcium entry (SOCE) and downregulated the expression of Orai1 in U87 cells. Inhibition of SOCE by 2-APB or stromal interaction molecule 1 (STIM1) downregulation both mimicked the effects of MMG on the invasion and migration potentials in U87 cells. Furthermore, upregulation of Orai1 significantly weakened the effects of MMG on the invasion and migration potentials in U87 cells. Therefore, these findings indicated that MMG stimulation inhibited the invasion and migration potentials of U87 cells by downregulating the expression of Orai1 and sequentially decreasing the SOCE, suggesting that MMG might be a new potential therapeutic strategy in glioblastoma treatment in the future. - Highlights: • Modeled microgravity (MMG) suppressed migration and invasion in U87 cells. • MMG downregulated the SOCE and the expression of Orai1. • SOCE inhibition mimicked the effects of MMG on migration and invasion potentials. • Restoration of SOCE diminished the effects of MMG on migration and invasion.

  7. eNOS activation and NO function: pregnancy adaptive programming of capacitative entry responses alters nitric oxide (NO) output in vascular endothelium--new insights into eNOS regulation through adaptive cell signaling.

    Science.gov (United States)

    Boeldt, D S; Yi, F X; Bird, I M

    2011-09-01

    In pregnancy, vascular nitric oxide (NO) production is increased in the systemic and more so in the uterine vasculature, thereby supporting maximal perfusion of the uterus. This high level of functionality is matched in the umbilical vein, and in corresponding disease states such as pre-eclampsia, reduced vascular responses are seen in both uterine artery and umbilical vein. In any endothelial cell, NO actually produced by endothelial NO synthase (eNOS) is determined by the maximum capacity of the cell (eNOS expression levels), eNOS phosphorylation state, and the intracellular [Ca(2+)](i) concentration in response to circulating hormones or physical forces. Herein, we discuss how pregnancy-specific reprogramming of NO output is determined as much by pregnancy adaptation of [Ca(2+)](i) signaling responses as it is by eNOS expression and phosphorylation. By examining the changes in [Ca(2+)](i) signaling responses from human hand vein endothelial cells, uterine artery endothelial cells, and human umbilical vein endothelial cells in (where appropriate) nonpregnant, normal pregnant, and pathological pregnant (pre-eclamptic) state, it is clear that pregnancy adaptation of NO output occurs at the level of sustained phase 'capacitative entry' [Ca(2+)](i) response, and the adapted response is lacking in pre-eclamptic pregnancies. Moreover, gap junction function is an essential permissive regulator of the capacitative response and impairment of NO output results from any inhibitor of gap junction function, or capacitative entry using TRPC channels. Identifying these [Ca(2+)](i) signaling mechanisms underlying normal pregnancy adaptation of NO output not only provides novel targets for future treatment of diseases of pregnancy but may also apply to other common forms of hypertension. PMID:21555345

  8. Fyn kinase controls FcεRI receptor-operated calcium entry necessary for full degranulation in mast cells

    International Nuclear Information System (INIS)

    IgE-antigen-dependent crosslinking of the high affinity IgE receptor (FcεRI) on mast cells leads to degranulation, leukotriene synthesis and cytokine production. Calcium (Ca2+) mobilization is a sine qua non requisite for degranulation, allowing the rapid secretion of stored pro-inflammatory mediators responsible for allergy symptoms. Fyn is a Src-family kinase that positively controls FcεRI-induced mast cell degranulation. However, our understanding of the mechanism connecting Fyn activation to secretion of pre-synthesized mediators is very limited. We analyzed FcεRI-dependent Ca2+ mobilization in bone marrow-derived mast cells (BMMCs) differentiated from WT and Fyn -/- knock out mice. Fyn -/- BMMCs showed a marked defect in extracellular Ca2+ influx after FcεRI crosslinking but not after thapsigargin addition. High concentrations of Gadolinium (Gd3+) partially blocked FcεRI-induced Ca2+ influx in WT cells but, in contrast, completely inhibited Ca2+ mobilization in Fyn -/- cells. Low concentrations of an inhibitor of the canonical transient receptor potential (TRPC) Ca2+ channels (2-aminoethoxyphenyl-borane, 2-APB) blocked FcεRI-induced maximal Ca2+ rise in WT but not in Fyn -/- cells. Ca2+ entry through Fyn-controlled, 2-APB sensitive channels was found to be important for full degranulation and IL-2 mRNA accumulation in WT cells. Immunoprecipitation assays showed that Fyn kinase interacts with TRPC 3/6/7 channels after IgE-antigen stimulation, but its association is not related to protein tyrosine phosphorylation. Results indicate Fyn kinase mediates the receptor-dependent activation of TRPC channels that contribute to degranulation in FcεRI-stimulated mast cells.

  9. Fyn kinase controls Fc{epsilon}RI receptor-operated calcium entry necessary for full degranulation in mast cells

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Miranda, Elizabeth; Ibarra-Sanchez, Alfredo [Departamento de Farmacobiologia, Centro de Investigacion y de Estudios Avanzados (Cinvestav), Sede Sur, Calzada de los Tenorios 235, Col. Granjas Coapa, CP 14330 Mexico City (Mexico); Gonzalez-Espinosa, Claudia, E-mail: cgonzal@cinvestav.mx [Departamento de Farmacobiologia, Centro de Investigacion y de Estudios Avanzados (Cinvestav), Sede Sur, Calzada de los Tenorios 235, Col. Granjas Coapa, CP 14330 Mexico City (Mexico)

    2010-01-22

    IgE-antigen-dependent crosslinking of the high affinity IgE receptor (Fc{epsilon}RI) on mast cells leads to degranulation, leukotriene synthesis and cytokine production. Calcium (Ca{sup 2+}) mobilization is a sine qua non requisite for degranulation, allowing the rapid secretion of stored pro-inflammatory mediators responsible for allergy symptoms. Fyn is a Src-family kinase that positively controls Fc{epsilon}RI-induced mast cell degranulation. However, our understanding of the mechanism connecting Fyn activation to secretion of pre-synthesized mediators is very limited. We analyzed Fc{epsilon}RI-dependent Ca{sup 2+} mobilization in bone marrow-derived mast cells (BMMCs) differentiated from WT and Fyn -/- knock out mice. Fyn -/- BMMCs showed a marked defect in extracellular Ca{sup 2+} influx after Fc{epsilon}RI crosslinking but not after thapsigargin addition. High concentrations of Gadolinium (Gd{sup 3+}) partially blocked Fc{epsilon}RI-induced Ca{sup 2+} influx in WT cells but, in contrast, completely inhibited Ca{sup 2+} mobilization in Fyn -/- cells. Low concentrations of an inhibitor of the canonical transient receptor potential (TRPC) Ca{sup 2+} channels (2-aminoethoxyphenyl-borane, 2-APB) blocked Fc{epsilon}RI-induced maximal Ca{sup 2+} rise in WT but not in Fyn -/- cells. Ca{sup 2+} entry through Fyn-controlled, 2-APB sensitive channels was found to be important for full degranulation and IL-2 mRNA accumulation in WT cells. Immunoprecipitation assays showed that Fyn kinase interacts with TRPC 3/6/7 channels after IgE-antigen stimulation, but its association is not related to protein tyrosine phosphorylation. Results indicate Fyn kinase mediates the receptor-dependent activation of TRPC channels that contribute to degranulation in Fc{epsilon}RI-stimulated mast cells.

  10. Homer1a attenuates glutamate-induced oxidative injury in HT-22 cells through regulation of store-operated calcium entry

    Science.gov (United States)

    Rao, Wei; Peng, Cheng; Zhang, Lei; Su, Ning; Wang, Kai; Hui, Hao; Dai, Shu-hui; Yang, Yue-fan; Luo, Peng; Fei, Zhou

    2016-01-01

    Calcium disequilibrium is extensively involved in oxidative stress-induced neuronal injury. Although Homer1a is known to regulate several neuronal calcium pathways, its effects on, or its exact relationship with, oxidative stress-induced neuronal injury has not yet been fully elucidated. We found that Homer1a protected HT-22 cells from glutamate-induced oxidative stress injury by inhibiting final-phase intracellular calcium overload and mitochondrial oxidative stress. In these cells, stromal interactive molecule 1 (STIM1) puncta, but not the protein level, was significantly increased after glutamate treatment. Store-operated calcium entry (SOCE) inhibitors and cells in which a key component of SOCE (STIM1) was knocked out were used as glutamate-induced oxidative stress injury models. Both models demonstrated significant improvement of HT-22 cell survival after glutamate treatment. Additionally, increased Homer1a protein levels significantly inhibited SOCE and decreased the association of STIM1-Orai1 triggered by glutamate. These results suggest that up-regulation of Homer1a can protect HT-22 cells from glutamate-induced oxidative injury by disrupting the STIM1-Oria1 association, and then by inhibiting the SOCE-mediated final-phrase calcium overload. Thus, regulation of Homer1a, either alone or in conjunction with SOCE inhibition, may serve as key therapeutic interventional targets for neurological diseases in which oxidative stress is involved in the etiology or progression of the disease. PMID:27681296

  11. Paclitaxel Induces Apoptosis in Breast Cancer Cells through Different Calcium—Regulating Mechanisms Depending on External Calcium Conditions

    Directory of Open Access Journals (Sweden)

    Zhi Pan

    2014-02-01

    Full Text Available Previously, we reported that endoplasmic reticulum calcium stores were a direct target for paclitaxel initiation of apoptosis. Furthermore, the actions of paclitaxel attenuated Bcl-2 resistance to apoptosis through endoplasmic reticulum-mediated calcium release. To better understand the calcium-regulated mechanisms of paclitaxel-induced apoptosis in breast cancer cells, we investigated the role of extracellular calcium, specifically; whether influx of extracellular calcium contributed to and/or was necessary for paclitaxel-induced apoptosis. Our results demonstrated that paclitaxel induced extracellular calcium influx. This mobilization of extracellular calcium contributed to subsequent cytosolic calcium elevation differently, depending on dosage. Under normal extracellular calcium conditions, high dose paclitaxel induced apoptosis-promoting calcium influx, which did not occur in calcium-free conditions. In the absence of extracellular calcium an “Enhanced Calcium Efflux” mechanism in which high dose paclitaxel stimulated calcium efflux immediately, leading to dramatic cytosolic calcium decrease, was observed. In the absence of extracellular calcium, high dose paclitaxel’s stimulatory effects on capacitative calcium entry and apoptosis could not be completely restored. Thus, normal extracellular calcium concentrations are critical for high dose paclitaxel-induced apoptosis. In contrast, low dose paclitaxel mirrored controls, indicating that it occurs independent of extracellular calcium. Thus, extracellular calcium conditions only affect efficacy of high dose paclitaxel-induced apoptosis.

  12. Reduced levels of intracellular calcium releasing in spermatozoa from asthenozoospermic patients

    Directory of Open Access Journals (Sweden)

    García Juan F

    2009-02-01

    Full Text Available Abstract Background Asthenozoospermia is one of the most common findings present in infertile males characterized by reduced or absent sperm motility, but its aetiology remains unknown in most cases. In addition, calcium is one of the most important ions regulating sperm motility. In this study we have investigated the progesterone-evoked intracellular calcium signal in ejaculated spermatozoa from men with normospermia or asthenozoospermia. Methods Human ejaculates were obtained from healthy volunteers and asthenospermic men by masturbation after 4–5 days of abstinence. For determination of cytosolic free calcium concentration, spermatozoa were loaded with the fluorescent ratiometric calcium indicator Fura-2. Results Treatment of spermatozoa from normospermic men with 20 micromolar progesterone plus 1 micromolar thapsigargin in a calcium free medium induced a typical transient increase in cytosolic free calcium concentration due to calcium release from internal stores. Similar results were obtained when spermatozoa were stimulated with progesterone alone. Subsequent addition of calcium to the external medium evoked a sustained elevation in cytosolic free calcium concentration indicative of capacitative calcium entry. However, when progesterone plus thapsigargin were administered to spermatozoa from patients with asthenozoospermia, calcium signal and subsequent calcium entry was much smaller compared to normospermic patients. As expected, pretreatment of normospermic spermatozoa with both the anti-progesterone receptor c262 antibody and with progesterone receptor antagonist RU-38486 decreased the calcium release induced by progesterone. Treatment of spermatozoa with cytochalasin D or jasplakinolide decreased the calcium entry evoked by depletion of internal calcium stores in normospermic patients, whereas these treatments proved to be ineffective at modifying the calcium entry in patients with asthenozoospermia. Conclusion Our results suggest

  13. Loss of primary cilia results in deregulated and unabated apical calcium entry in ARPKD collecting duct cells.

    Science.gov (United States)

    Siroky, Brian J; Ferguson, William B; Fuson, Amanda L; Xie, Yi; Fintha, Attila; Komlosi, Peter; Yoder, Bradley K; Schwiebert, Erik M; Guay-Woodford, Lisa M; Bell, P Darwin

    2006-06-01

    Recent genetic analysis has identified a pivotal role of primary cilia in the pathogenesis of polycystic kidney disease (PKD). However, little is known regarding how cilia loss/dysfunction contributes to cyst development. In epithelial cells, changes in apical fluid flow induce cilia-mediated Ca2+ entry via polycystin-2 (PC2), a cation channel. The Oak Ridge Polycystic Kidney (orpk) mouse contains a mutated Tg737 gene that disrupts expression of polaris, a protein required for ciliogenesis. These studies examine the effect of cilia malformation on Ca2+ entry in orpk cilia(-) collecting duct principal cells, and in orpk cells in which wild-type Tg737 was reintroduced, orpk cilia(+). [Ca2+]i was monitored in confluent cell monolayers using fluorescence microscopy. Intrinsic apical Ca2+ entry was measured by Mn2+ quenching and Ca2+ depletion/readdition under flow conditions below the threshold for stimulation. We found that unstimulated apical Ca2+ entry was markedly increased in cilia(-) cells and was sensitive to Gd3+, an inhibitor of PC2. Electrophysiological measurements demonstrate increased abundance of an apical channel, consistent with PC2, in cilia(-) cells. Immunofluorescence studies revealed that PC2, normally expressed on and at the base of cilia in orpk cilia(+) cells, was observed throughout the apical membrane in cilia(-) cells. Furthermore, cilia(-) cells displayed elevated subapical Ca2+ levels measured with the near-membrane Ca2+ indicator FFP-18. We propose that cilia exert a tonic regulatory influence on apical Ca2+ entry, and absence of cilia results in loss of spatial organization of PC2, causing unregulated Ca2+ entry and elevations in subapical [Ca2+], a factor which may contribute to cyst formation. PMID:16396941

  14. Activation of ERK1/2 by store-operated calcium entry in rat parotid acinar cells.

    Directory of Open Access Journals (Sweden)

    Stephen P Soltoff

    Full Text Available The regulation of intracellular Ca(2+ concentration ([Ca(2+]i plays a critical role in a variety of cellular processes, including transcription, protein activation, vesicle trafficking, and ion movement across epithelial cells. In many cells, the activation of phospholipase C-coupled receptors hydrolyzes membrane phosphoinositides and produces the depletion of endoplasmic reticulum Ca(2+ stores, followed by the sustained elevation of [Ca(2+]i from Ca(2+ entry across the plasma membrane via store-operated Ca(2+ entry (SOCE. Ca(2+ entry is also increased in a store-independent manner by arachidonate-regulated Ca(2+ (ARC channels. Using rat parotid salivary gland cells, we examined multiple pathways of Ca(2+ entry/elevation to determine if they activated cell signaling proteins and whether this occurred in a pathway-dependent manner. We observed that SOCE activates extracellular signal-related kinases 1 and 2 (ERK1/2 to ∼3-times basal levels via a receptor-independent mechanism when SOCE was initiated by depleting Ca(2+ stores using the endoplasmic reticulum Ca(2+-ATPase inhibitor thapsigargin (TG. TG-initiated ERK1/2 phosphorylation increased as rapidly as that initiated by the muscarinic receptor agonist carbachol, which promoted an increase to ∼5-times basal levels. Notably, ERK1/2 phosphorylation was not increased by the global elevation of [Ca(2+]i by Ca(2+ ionophore or by Ca(2+ entry via ARC channels in native cells, although ERK1/2 phosphorylation was increased by Ca(2+ ionophore in Par-C10 and HSY salivary cell lines. Agents and conditions that blocked SOCE in native cells, including 2-aminoethyldiphenyl borate (2-APB, SKF96363, and removal of extracellular Ca(2+, also reduced TG- and carbachol-stimulated ERK1/2 phosphorylation. TG-promoted ERK1/2 phosphorylation was blocked when SRC and Protein Kinases C (PKC were inhibited, and it was blocked in cells pretreated with β-adrenergic agonist isoproterenol. These observations demonstrate

  15. 白血病HL-60细胞的电容性钙内流:粉防己碱与SK&F96365作为探测药%Capacitative Ca2 + entry in HL-60 cells: tetrandrine and SK&F 96365 as probes

    Institute of Scientific and Technical Information of China (English)

    梁育民; 關超然; 羅逹德

    1996-01-01

    @@ Agonist-activated Ca2 + entry is important in many bioogical responses such as secretion and cell growth[1,2]. In nonexcitable cells which have no voltage-operated Ca2 + channels (VOCC), agonist-receptor interaction can trigger Ca2 +entry across the plasmalemma via several entry pathways[1 -3](Fig 1): (A) channels which are intrinsic structures of the receptor ( receptor-operated channels), (B) channels which are coupled to receptors via a G-protein (G-protein-operated channels), (C) channels which are activated by some second messengers (second-messenger-operated channels), and (D)channels which open upon intracellular nonmitochondrial Ca2 +store depletion ( Ca2 + release-activated channels) resulting from inositol 1, 4, 5-trisphosphate-induced Ca2+ release or inhibition of Ca2+ re-uptake (see next section). Ca2+ entry via the 4th type of channel, also known as "capacitative Ca2 + entry" (CCE)[4], has aroused much interest in the past decade because of its intriguing nature as retrograde signalling. In this brief review, we present the evidence for and the possible biochemical processes involved in CCE. We also discuss the use of 2 novel Ca2+ entry blockers: tetrandrine and SK&F 96365. Emphasis will be put on the human leukemic HL-60cell line, a popular cell system for intracellular Ca2 + homeostasis studies and also a model the signal transduction of which we have been investigating during the past few years.

  16. 电容吸附法海水脱钙研究%STUDY ON CALCIUM REMOVAL FROM SEAWATER BY CAPACITIVE DEIONIZATION

    Institute of Scientific and Technical Information of China (English)

    李敏; 袁俊生; 张运秋; 付云朋

    2012-01-01

    Adding a certain proportion modified molecular sieve to the activated carbon to make composite electrodes, the elimination ratio for calcium ion of the composite electrodes were measured under different adsorption time, molecular sieve content, voltage, distance between the electrodes and weight of the electrodes. At the same time, the adsorptive capacity of calcium ion between composite electrodes and the common activated carbon electrodes were compared. The results showed that in the solution of Ca2+Na+, the adsorption of calcium ion increased by 1.08 times. In the solution of Ca2+/Mg2+ and Ca2+/ K+, the adsorption capacity of calcium ion increased by 0.6 and 7.45 times. In the seawater, the adsorptive capacity increased by 2 times.%将改性的LSX分子筛按一定比例掺加到活性炭中,制成复合电极(CE),测定了其在不同的吸附时间、分子筛含量、电压、电极间距、电极片质量下,该复合电极对钙离子的去除率.同时比较了其与普通活性炭电极(AC)对钙离子的吸附能力.结果表明,在Ca2+/Na+溶液中,钙离子吸附量提高了1.08倍,在Ca2+/Mg2+溶液中,钙离子吸附量提高了0.6倍,在Ca2+/K+溶液中,吸附量提高了7.45倍,在海水溶液中,吸附量提高了2倍.

  17. False capacitance of supercapacitors

    OpenAIRE

    Ragoisha, G. A.; Aniskevich, Y. M.

    2016-01-01

    Capacitance measurements from cyclic voltammetry, galvanostatic chronopotentiometry and calculation of capacitance from imaginary part of impedance are widely used in investigations of supercapacitors. The methods assume the supercapacitor is a capacitor, while real objects correspond to different equivalent electric circuits and show various contributions of non-capacitive currents to the current which is used for calculation of capacitance. Specific capacitances which are presented in F g-1...

  18. Effect of calcium entry blockers on blood pressure and vasoconstrictor responses to alpha-1 adrenoceptor stimulation in conscious spontaneously hypertensive rats

    International Nuclear Information System (INIS)

    In order to investigate whether vascular alpha-1 adrenoceptor antagonism plays a role in the antihypertensive effect of verapamil, tiapamil, and nifedipine, we studied their potencies to inhibit K(+)-induced 45Ca2+ influx in rat isolated aorta and [3H]prazosin binding in rat brain membranes in vitro as well as their antihypertensive effect and functional alpha-1 adrenoceptor blockade in conscious spontaneously hypertensive rats (SHR) in vivo. Tiapamil proved 70 times less potent than verapamil in inhibiting calcium influx, but was equipotent in displacing [3H]prazosin. Nifedipine proved 10 times more potent than verapamil as calcium channel blocker but displayed negligible affinity for alpha-1 adrenoceptors in vitro. In conscious SHR, the three calcium channel blockers dose-dependently reduced mean arterial pressure after oral administration. Only at maximal anti-hypertensive doses, the increases in diastolic pressure to intravenous injection of the selective alpha-1 adrenoceptor agonist cirazoline were temporarily suppressed by nifedipine, verapamil, and tiapamil. No relationship existed between the relative potencies as calcium channel blocker and affinities for alpha-1 adrenoceptor binding sites in vitro with functional vascular alpha-1 adrenoceptor blockade in vivo. The data do not support the hypothesis that vascular alpha-1 adrenoceptor blockade plays a significant role in the anti-hypertensive effect of verapamil and related calcium channel blockers

  19. Prostaglandin modulation of mouse and human sperm capacitation.

    Science.gov (United States)

    Herrero, M B; Viggiano, J M; Boquet, M; Gimeno, M A

    1997-09-01

    To determine whether prostaglandins produce a capacitation and/or acrosome reaction, the effect of prostaglandins on capacitated mouse spermatozoa and the effect of prostaglandin pre-incubation on human and mouse spermatozoa were studied. Prostaglandins did not induce an acrosome reaction in capacitated mouse sperm. PGE1 pre-incubation in a protein-free medium enhanced acrosome loss of mouse sperm challenged with A-23187 or solubilized mouse zona pellucida. Human sperm were pre-incubated in media containing prostaglandins, and an acrosome reaction was induced with calcium ionophore or human follicular fluid. PGE1 pre-incubation enhanced acrosome loss by human sperm when the action was induced with calcium ionophore, but had no effect on follicular fluid induction. We conclude that PGE1 acts as a capacitating factor in vitro for mouse spermatozoa, and enhances acrosome-reaction induction with calcium ionophore in human spermatozoa.

  20. Ginsenoside Rb1 Attenuates Agonist-Induced Contractile Response via Inhibition of Store-Operated Calcium Entry in Pulmonary Arteries of Normal and Pulmonary Hypertensive Rats

    Directory of Open Access Journals (Sweden)

    Rui-Xing Wang

    2015-03-01

    Full Text Available Background: Pulmonary hypertension (PH is characterized by sustained vasoconstriction, enhanced vasoreactivity and vascular remodeling, which leads to right heart failure and death. Despite several treatments are available, many forms of PH are still incurable. Ginsenoside Rb1, a principle active ingredient of Panax ginseng, exhibits multiple pharmacological effects on cardiovascular system, and suppresses monocrotaline (MCT-induced right heart hypertrophy. However, its effect on the pulmonary vascular functions related to PH is unknown. Methods: We examined the vasorelaxing effects of ginsenoside Rb1 on endothelin-1 (ET-1 induced contraction of pulmonary arteries (PAs and store-operated Ca2+ entry (SOCE in pulmonary arterial smooth muscle cells (PASMCs from chronic hypoxia (CH and MCT-induced PH. Results: Ginsenoside Rb1 elicited concentration-dependent relaxation of ET-1-induced PA contraction. The vasorelaxing effect was unaffected by nifedipine, but abolished by the SOCE blocker Gd3+. Ginsenoside Rb1 suppressed cyclopiazonic acid (CPA-induced PA contraction, and CPA-activated cation entry and Ca2+ transient in PASMCs. ET-1 and CPA-induced contraction, and CPA-activated cation entry and Ca2+ transients were enhanced in PA and PASMCs of CH and MCT-treated rats; the enhanced responses were abolished by ginsenoside Rb1. Conclusion: Ginsenoside Rb1 attenuates ET-1-induced contractile response via inhibition of SOCE, and it can effectively antagonize the enhanced pulmonary vasoreactivity in PH.

  1. Calmidazolium evokes high calcium fluctuations in Plasmodium falciparum.

    Science.gov (United States)

    Budu, Alexandre; Gomes, Mayrim M; Melo, Pollyana M; El Chamy Maluf, Sarah; Bagnaresi, Piero; Azevedo, Mauro F; Carmona, Adriana K; Gazarini, Marcos L

    2016-03-01

    Calcium and calmodulin (CaM) are important players in eukaryote cell signaling. In the present study, by using a knockin approach, we demonstrated the expression and localization of CaM in all erythrocytic stages of Plasmodium falciparum. Under extracellular Ca(2+)-free conditions, calmidazolium (CZ), a potent CaM inhibitor, promoted a transient cytosolic calcium ([Ca(2+)]cyt) increase in isolated trophozoites, indicating that CZ mobilizes intracellular sources of calcium. In the same extracellular Ca(2+)-free conditions, the [Ca(2+)]cyt rise elicited by CZ treatment was ~3.5 fold higher when the endoplasmic reticulum (ER) calcium store was previously depleted ruling out the mobilization of calcium from the ER by CZ. The effects of the Ca(2+)/H(+) ionophore ionomycin (ION) and the Na(+)/H(+) ionophore monensin (MON) suggest that the [Ca(2+)]cyt-increasing effect of CZ is driven by the removal of Ca(2+) from at least one Ca(2+)-CaM-related (CaMR) protein as well as by the mobilization of Ca(2+) from intracellular acidic calcium stores. Moreover, we showed that the mitochondrion participates in the sequestration of the cytosolic Ca(2+) elicited by CZ. Finally, the modulation of membrane Ca(2+) channels by CZ and thapsigargin (THG) was demonstrated. The opened channels were blocked by the unspecific calcium channel blocker Co(2+) but not by 2-APB (capacitative calcium entry inhibitor) or nifedipine (L-type Ca(2+) channel inhibitor). Taken together, the results suggested that one CaMR protein is an important modulator of calcium signaling and homeostasis during the Plasmodium intraerythrocytic cell cycle, working as a relevant intracellular Ca(2+) reservoir in the parasite. PMID:26689736

  2. Human ether à-gogo K(+) channel 1 (hEag1) regulates MDA-MB-231 breast cancer cell migration through Orai1-dependent calcium entry.

    Science.gov (United States)

    Hammadi, Mehdi; Chopin, Valérie; Matifat, Fabrice; Dhennin-Duthille, Isabelle; Chasseraud, Maud; Sevestre, Henri; Ouadid-Ahidouch, Halima

    2012-12-01

    Breast cancer (BC) has a poor prognosis due to its strong metastatic ability. Accumulating data present ether à go-go (hEag1) K(+) channels as relevant player in controlling cell cycle and proliferation of non-invasive BC cells. However, the role of hEag1 in invasive BC cells migration is still unknown. In this study, we studied both the functional expression and the involvement in cell migration of hEag1 in the highly metastatic MDA-MB-231 human BC cells. We showed that hEag1 mRNA and proteins were expressed in human invasive ductal carcinoma tissues and BC cell lines. Functional activity of hEag1 channels in MDA-MB-231 cells was confirmed using astemizole, a hEag1 blocker, or siRNA. Blocking or silencing hEag1 depolarized the membrane potential and reduced both Ca(2+) entry and MDA-MB-231 cell migration without affecting cell proliferation. Recent studies have reported that Ca(2+) entry through Orai1 channels is required for MDA-MB-231 cell migration. Down-regulation of hEag1 or Orai1 reduced Ca(2+) influx and cell migration with similar efficiency. Interestingly, no additive effects on Ca(2+) influx or cell migration were observed in cells co-transfected with sihEag1 and siOrai1. Finally, both Orai1 and hEag1 are expressed in invasive breast adenocarcinoma tissues and invaded metastatic lymph node samples (LNM(+)). In conclusion, this study is the first to demonstrate that hEag1 channels are involved in the serum-induced migration of BC cells by controlling the Ca(2+) entry through Orai1 channels. hEag1 may therefore represent a potential target for the suppression of BC cell migration, and thus prevention of metastasis development.

  3. Human ether à-gogo K(+) channel 1 (hEag1) regulates MDA-MB-231 breast cancer cell migration through Orai1-dependent calcium entry.

    Science.gov (United States)

    Hammadi, Mehdi; Chopin, Valérie; Matifat, Fabrice; Dhennin-Duthille, Isabelle; Chasseraud, Maud; Sevestre, Henri; Ouadid-Ahidouch, Halima

    2012-12-01

    Breast cancer (BC) has a poor prognosis due to its strong metastatic ability. Accumulating data present ether à go-go (hEag1) K(+) channels as relevant player in controlling cell cycle and proliferation of non-invasive BC cells. However, the role of hEag1 in invasive BC cells migration is still unknown. In this study, we studied both the functional expression and the involvement in cell migration of hEag1 in the highly metastatic MDA-MB-231 human BC cells. We showed that hEag1 mRNA and proteins were expressed in human invasive ductal carcinoma tissues and BC cell lines. Functional activity of hEag1 channels in MDA-MB-231 cells was confirmed using astemizole, a hEag1 blocker, or siRNA. Blocking or silencing hEag1 depolarized the membrane potential and reduced both Ca(2+) entry and MDA-MB-231 cell migration without affecting cell proliferation. Recent studies have reported that Ca(2+) entry through Orai1 channels is required for MDA-MB-231 cell migration. Down-regulation of hEag1 or Orai1 reduced Ca(2+) influx and cell migration with similar efficiency. Interestingly, no additive effects on Ca(2+) influx or cell migration were observed in cells co-transfected with sihEag1 and siOrai1. Finally, both Orai1 and hEag1 are expressed in invasive breast adenocarcinoma tissues and invaded metastatic lymph node samples (LNM(+)). In conclusion, this study is the first to demonstrate that hEag1 channels are involved in the serum-induced migration of BC cells by controlling the Ca(2+) entry through Orai1 channels. hEag1 may therefore represent a potential target for the suppression of BC cell migration, and thus prevention of metastasis development. PMID:22495877

  4. Mitochondrial calcium uniporter MCU supports cytoplasmic Ca2+ oscillations, store-operated Ca2+ entry and Ca2+-dependent gene expression in response to receptor stimulation.

    Science.gov (United States)

    Samanta, Krishna; Douglas, Sophie; Parekh, Anant B

    2014-01-01

    Ca2+ flux into mitochondria is an important regulator of cytoplasmic Ca2+ signals, energy production and cell death pathways. Ca2+ uptake can occur through the recently discovered mitochondrial uniporter channel (MCU) but whether the MCU is involved in shaping Ca2+ signals and downstream responses to physiological levels of receptor stimulation is unknown. Here, we show that modest stimulation of leukotriene receptors with the pro-inflammatory signal LTC4 evokes a series of cytoplasmic Ca2+ oscillations that are rapidly and faithfully propagated into mitochondrial matrix. Knockdown of MCU or mitochondrial depolarisation, to reduce the driving force for Ca2+ entry into the matrix, prevents the mitochondrial Ca2+ rise and accelerates run down of the oscillations. The loss of cytoplasmic Ca2+ oscillations appeared to be a consequence of enhanced Ca2+-dependent inactivation of InsP3 receptors, which arose from the loss of mitochondrial Ca2+ buffering. Ca2+ dependent gene expression in response to leukotriene receptor activation was suppressed following knockdown of the MCU. In addition to buffering Ca2+ release, mitochondria also sequestrated Ca2+ entry through store-operated Ca2+ channels and this too was prevented following loss of MCU. MCU is therefore an important regulator of physiological pulses of cytoplasmic Ca2+.

  5. Mitochondrial calcium uniporter MCU supports cytoplasmic Ca2+ oscillations, store-operated Ca2+ entry and Ca2+-dependent gene expression in response to receptor stimulation.

    Directory of Open Access Journals (Sweden)

    Krishna Samanta

    Full Text Available Ca2+ flux into mitochondria is an important regulator of cytoplasmic Ca2+ signals, energy production and cell death pathways. Ca2+ uptake can occur through the recently discovered mitochondrial uniporter channel (MCU but whether the MCU is involved in shaping Ca2+ signals and downstream responses to physiological levels of receptor stimulation is unknown. Here, we show that modest stimulation of leukotriene receptors with the pro-inflammatory signal LTC4 evokes a series of cytoplasmic Ca2+ oscillations that are rapidly and faithfully propagated into mitochondrial matrix. Knockdown of MCU or mitochondrial depolarisation, to reduce the driving force for Ca2+ entry into the matrix, prevents the mitochondrial Ca2+ rise and accelerates run down of the oscillations. The loss of cytoplasmic Ca2+ oscillations appeared to be a consequence of enhanced Ca2+-dependent inactivation of InsP3 receptors, which arose from the loss of mitochondrial Ca2+ buffering. Ca2+ dependent gene expression in response to leukotriene receptor activation was suppressed following knockdown of the MCU. In addition to buffering Ca2+ release, mitochondria also sequestrated Ca2+ entry through store-operated Ca2+ channels and this too was prevented following loss of MCU. MCU is therefore an important regulator of physiological pulses of cytoplasmic Ca2+.

  6. Mesoscopic Capacitance Oscillations

    OpenAIRE

    Buttiker, Markus; Nigg, Simon

    2006-01-01

    We examine oscillations as a function of Fermi energy in the capacitance of a mesoscopic cavity connected via a single quantum channel to a metallic contact and capacitively coupled to a back gate. The oscillations depend on the distribution of single levels in the cavity, the interaction strength and the transmission probability through the quantum channel. We use a Hartree-Fock approach to exclude self-interaction. The sample specific capacitance oscillations are in marked contrast to the c...

  7. Calcium binding protein-mediated regulation of voltage-gated calcium channels linked to human diseases

    Institute of Scientific and Technical Information of China (English)

    Nasrin NFJATBAKHSH; Zhong-ping FENG

    2011-01-01

    Calcium ion entry through voltage-gated calcium channels is essential for cellular signalling in a wide variety of cells and multiple physiological processes. Perturbations of voltage-gated calcium channel function can lead to pathophysiological consequences. Calcium binding proteins serve as calcium sensors and regulate the calcium channel properties via feedback mechanisms. This review highlights the current evidences of calcium binding protein-mediated channel regulation in human diseases.

  8. A nonsense mutation of Stim1 identified in stroke-prone spontaneously hypertensive rats decreased the store-operated calcium entry in astrocytes.

    Science.gov (United States)

    Ohara, Hiroki; Nabika, Toru

    2016-08-01

    We previously identified a nonsense mutation in the stromal interaction molecule-1 (Stim1) resulting in expression of a truncated STIM1 in the stroke-prone spontaneously hypertensive rat (SHRSP). In this study, we evaluated activity of the store-operated Ca(2+)-entry (SOCE) regulated by STIM1 to clarify putative functional abnormalities of the truncated STIM1. As a result, reduced SOCE activity resulting in suppression of cyclooxygenase-2 expression induced by SOCE was found in cultured astrocytes with the truncated STIM1 when compared with those with the wild-type. Our results indicated that the truncated STIM1 impaired Ca(2+) signaling regulated by SOCE and that the impaired SOCE activity might be responsible for pathological phenotypes in SHRSP. PMID:27237974

  9. Anti-tumor Necrosis Factor Alpha (Infliximab) Attenuates Apoptosis, Oxidative Stress, and Calcium Ion Entry Through Modulation of Cation Channels in Neutrophils of Patients with Ankylosing Spondylitis.

    Science.gov (United States)

    Ugan, Yunus; Nazıroğlu, Mustafa; Şahin, Mehmet; Aykur, Mehmet

    2016-08-01

    Ankylosing Spondylitis (AS) is known to be associated with increased neutrophil activation and oxidative stress, however, the mechanism of neutrophil activation is still unclear. We have hypothesized that the antioxidant and anti-tumor necrosis factor properties of infliximab may affect intracellular Ca(2+) concentration in the neutrophils of AS patients. The objective of this study was to investigate the effects of infliximab on calcium signaling, oxidative stress, and apoptosis in neutrophils of AS patients. Neutrophils collected from ten patients with AS and ten healthy controls were used in the study. In a cell viability test, the ideal non-toxic dose and incubation time of infliximab were found as 100 μM and 1 h, respectively. In some experiments, the neutrophils were incubated with the voltage-gated calcium channel (VGCC) blockers verapamil + diltiazem (V + D) and the TRPM2 channel blocker 2-aminoethyl diphenylborinate (2-APB). Intracellular Ca(2+) concentration, lipid peroxidation, apoptosis, caspase 3, and caspase 9 values were high in neutrophils of AS patients and were reduced with infliximab treatment. Reduced glutathione level and glutathione peroxidase activity were low in the patients and increased with infliximab treatment. The intracellular Ca(2+) concentrations were low in 2-APB and V + D groups. In conclusion, the current study suggests that infliximab is useful against apoptotic cell death and oxidative stress in neutrophils of patients with AS, which seem to be dependent on increased levels of intracellular Ca(2+) through activation of TRPM2 and VGCC. PMID:26956056

  10. Variable Synthetic Capacitance

    Science.gov (United States)

    Kleinberg, L. L.

    1986-01-01

    Feedback amplifier circuit synthesizes electronically variable capacitance. Variable Synthetic Capacitor is amplifier circuit with follower/feedback configuration. Effective input capacitance depends on input set current. If synthetic capacitor is connected across resonant element of oscillator, oscillator frequency controlled via input set current. Circuit especially suitable for fine frequency adjustments of piezoelectric-crystal or inductor/capacitor resonant oscillators.

  11. Hydrogen peroxide generation induces pp60src activation in human platelets: evidence for the involvement of this pathway in store-mediated calcium entry.

    Science.gov (United States)

    Rosado, Juan A; Redondo, Pedro C; Salido, Ginés M; Gómez-Arteta, Emilio; Sage, Stewart O; Pariente, Jose A

    2004-01-16

    Reactive oxygen species, such as H2O2, have been recognized as intracellular messengers involved in several cell functions. Here we report the activation of the tyrosine kinase pp60(src) by H2O2, a mechanism required for the activation of store-mediated Ca2+ entry (SMCE) in human platelets. Treatment of platelets with H2O2 resulted in a time- and concentration-dependent activation of pp60(src). Incubation with GF 109203X, a protein kinase C (PKC) inhibitor, prevented H2O2-induced pp60(src) activation. In contrast, dimethyl-BAPTA loading did not affect this response, suggesting that activation of pp60(src) by H2O2 is independent of increases in [Ca2+](i). Cytochalasin D, an inhibitor of actin polymerization, significantly reduced H2O2-induced pp60(src) activation. We found that platelet stimulation with thapsigargin (TG) plus ionomycin (Iono) or thrombin induced rapid H2O2 production, a mechanism independent of elevations in [Ca2+](i). Treatment of platelets with catalase attenuated TG plus Iono- and thrombin-induced activation of pp60(src). In addition, catalase as well as the pp60(src) inhibitor, PP1, reduced both the activation of SMCE and the coupling between the hTrp1 and the IP(3)R type II without having any effect on the maintenance of SMCE. Consistent with the role of PKC in the activation of pp60(src) by H2O2, the PKC inhibitors GF 109202X and Ro-31-8220 were found to reduced SMCE in platelets. This study suggests that platelet activation with TG plus Iono or thrombin is associated with H2O2 production, which acts as a second messenger by stimulating pp60(src) by a PKC-dependent pathway and is involved in the activation of SMCE in these cells.

  12. Dual pathways of calcium entry in spike and plateau phases of luteinizing hormone release from chicken pituitary cells: sequential activation of receptor-operated and voltage-sensitive calcium channels by gonadotropin-releasing hormone

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, J.S.; Wakefield, I.K.; King, J.A.; Mulligan, G.P.; Millar, R.P.

    1988-04-01

    It has previously been shown that, in pituitary gonadotrope cells, the initial rise in cytosolic Ca2+ induced by GnRH is due to a Ca2+ mobilization from intracellular stores. This raises the possibility that the initial transient spike phase of LH release might be fully or partially independent of extracellular Ca2+. We have therefore characterized the extracellular Ca2+ requirements, and the sensitivity to Ca2+ channel blockers, of the spike and plateau phases of secretion separately. In the absence of extracellular Ca2+ the spike and plateau phases were inhibited by 65 +/- 4% and 106 +/- 3%, respectively. Both phases exhibited a similar dependence on concentration of extracellular Ca2+. However, voltage-sensitive Ca2+ channel blockers D600 and nifedipine had a negligible effect on the spike phase, while inhibiting the plateau phase by approximately 50%. In contrast, ruthenium red, Gd3+ ions, and Co2+ ions inhibited both spike and plateau phases to a similar extent as removal of extracellular Ca2+. A fraction (35 +/- 4%) of spike phase release was resistant to removal of extracellular Ca2+. This fraction was abolished after calcium depletion of the cells by preincubation with EGTA in the presence of calcium ionophore A23187, indicating that it depends on intracellular Ca2+ stores. Neither absence of extracellular Ca2+, nor the presence of ruthenium red or Gd3+ prevented mobilization of 45Ca2+ from intracellular stores by GnRH. We conclude that mobilization of intracellular stored Ca2+ is insufficient by itself to account for full spike phase LH release.

  13. Electromagnetic radiation (Wi-Fi) and epilepsy induce calcium entry and apoptosis through activation of TRPV1 channel in hippocampus and dorsal root ganglion of rats.

    Science.gov (United States)

    Ghazizadeh, Vahid; Nazıroğlu, Mustafa

    2014-09-01

    Incidence rates of epilepsy and use of Wi-Fi worldwide have been increasing. TRPV1 is a Ca(2+) permeable and non-selective channel, gated by noxious heat, oxidative stress and capsaicin (CAP). The hyperthermia and oxidant effects of Wi-Fi may induce apoptosis and Ca(2+) entry through activation of TRPV1 channel in epilepsy. Therefore, we tested the effects of Wi-Fi (2.45 GHz) exposure on Ca(2+) influx, oxidative stress and apoptosis through TRPV1 channel in the murine dorsal root ganglion (DRG) and hippocampus of pentylentetrazol (PTZ)-induced epileptic rats. Rats in the present study were divided into two groups as controls and PTZ. The PTZ groups were divided into two subgroups namely PTZ + Wi-Fi and PTZ + Wi-Fi + capsazepine (CPZ). The hippocampal and DRG neurons were freshly isolated from the rats. The DRG and hippocampus in PTZ + Wi-Fi and PTZ + Wi-Fi + CPZ groups were exposed to Wi-Fi for 1 hour before CAP stimulation. The cytosolic free Ca(2+), reactive oxygen species production, apoptosis, mitochondrial membrane depolarization, caspase-3 and -9 values in hippocampus were higher in the PTZ group than in the control although cell viability values decreased. The Wi-Fi exposure induced additional effects on the cytosolic Ca(2+) increase. However, pretreatment of the neurons with CPZ, results in a protection against epilepsy-induced Ca(2+) influx, apoptosis and oxidative damages. In results of whole cell patch-clamp experiments, treatment of DRG with Ca(2+) channel antagonists [thapsigargin, verapamil + diltiazem, 2-APB, MK-801] indicated that Wi-Fi exposure induced Ca(2+) influx via the TRPV1 channels. In conclusion, epilepsy and Wi-Fi in our experimental model is involved in Ca(2+) influx and oxidative stress-induced hippocampal and DRG death through activation of TRPV1 channels, and negative modulation of this channel activity by CPZ pretreatment may account for the neuroprotective activity against oxidative stress.

  14. Capacitive chemical sensor

    Science.gov (United States)

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

    2014-05-27

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

  15. System for Measuring Capacitance

    Science.gov (United States)

    McNichol, Randal S. (Inventor)

    2001-01-01

    A system has been developed for detecting the level of a liquid in a tank wherein a capacitor positioned in the tank has spaced plates which are positioned such that the dielectric between the plates will be either air or the liquid, depending on the depth of the liquid in the tank. An oscillator supplies a sine wave current to the capacitor and a coaxial cable connects the capacitor to a measuring circuit outside the tank. If the cable is very long or the capacitance to be measured is low, the capacitance inherent in the coaxial cable will prevent an accurate reading. To avoid this problem, an inductor is connected across the cable to form with the capacitance of the cable a parallel resonant circuit. The impedance of the parallel resonant circuit is infinite, so that attenuation of the measurement signal by the stray cable capacitance is avoided.

  16. Capacitance pressure sensor

    Science.gov (United States)

    Eaton, William P.; Staple, Bevan D.; Smith, James H.

    2000-01-01

    A microelectromechanical (MEM) capacitance pressure sensor integrated with electronic circuitry on a common substrate and a method for forming such a device are disclosed. The MEM capacitance pressure sensor includes a capacitance pressure sensor formed at least partially in a cavity etched below the surface of a silicon substrate and adjacent circuitry (CMOS, BiCMOS, or bipolar circuitry) formed on the substrate. By forming the capacitance pressure sensor in the cavity, the substrate can be planarized (e.g. by chemical-mechanical polishing) so that a standard set of integrated circuit processing steps can be used to form the electronic circuitry (e.g. using an aluminum or aluminum-alloy interconnect metallization).

  17. Induced Charge Capacitive Deionization

    OpenAIRE

    Rubin, S.; Suss, M. E.; Biesheuvel, P. M.; Bercovici, M.

    2016-01-01

    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, ...

  18. Nonlinear Quantum Capacitance

    OpenAIRE

    Wang, B; Zhao, X; Guo, H; Wang, J.

    1999-01-01

    We analyze the nonlinear voltage dependence of electrochemical capacitance for nanoscale conductors. This voltage dependence is due to the finite density of states of the conductors. Within Hartree theory we derive an exact expression for the electrochemical capacitance–voltage curve for a parallel plate system. The result suggests a quantum scanning capacitance microscopy at the nanoscale: by inverting the capacitance–voltage expression one is able to deduce the local spectral function of th...

  19. Quantum capacitance: a microscopic derivation

    OpenAIRE

    Mukherjee, Sreemoyee; MANNINEN, M; Deo, P. Singha

    2010-01-01

    We start from microscopic approach to many body physics and show the analytical steps and approximations required to arrive at the concept of quantum capacitance. These approximations are valid only in the semi-classical limit and the quantum capacitance in that case is determined by Lindhard function. The effective capacitance is the geometrical capacitance and the quantum capacitance in series, and this too is established starting from a microscopic theory.

  20. Membrane capacitive deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Wal, van der A.

    2010-01-01

    Membrane capacitive deionization (MCDI) is an ion-removal process based on applying an electrical potential difference across an aqueous solution which flows in between oppositely placed porous electrodes, in front of which ion-exchange membranes are positioned. Due to the applied potential, ions ar

  1. Steerable Capacitive Proximity Sensor

    Science.gov (United States)

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Steerable capacitive proximity sensor of "capaciflector" type based partly on sensing units described in GSC-13377 and GSC-13475. Position of maximum sensitivity adjusted without moving sensor. Voltage of each driven shield adjusted separately to concentrate sensing electric field more toward one side or other.

  2. Digital capacitance measuring system

    Science.gov (United States)

    1973-01-01

    The hardware phase of a digital capacitance measuring system is presented with the major emphasis placed on the electrical design and operation. Test results are included of the three units fabricated. The system's interface is applicable to existing requirements for the space shuttle vehicle.

  3. Induced Charge Capacitive Deionization

    CERN Document Server

    Rubin, S; Biesheuvel, P M; Bercovici, M

    2016-01-01

    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, which leads to rapid and significant deionization of ionic species from a volume which is on the scale of the particle. We show by theory and experiment that the transient response around a cylindrical particle results in spatially non-uniform charging and non-steady growth of depletion regions which emerge around the particle's poles. Potentially, ICCDI can be useful in applications where fast concentration changes of ionic species are required over large volumes.

  4. Design of Capacitance to Voltage Converter for Capacitive Sensor Transducer

    Directory of Open Access Journals (Sweden)

    A. H.M.Z. Alam

    2010-01-01

    Full Text Available Problem statement: The design of Capacitance to Voltage Converter (CVC for capacitive sensor transducer was presented. The proposed design will reduce the size, power consumption and supply voltage of the circuit and can be used in high frequency band transducer. Approach: The design was implemented using the Operational amplifier (Op amp and capacitive network. The circuit was simulated using the PSPICE model parameters based on standard 0.13 μm CMOS process. Results: The design was able to measure a wide range of capacitance variations for the capacitive transducer. The performance analysis of the design showed desirable performance parameters in terms of response, low power consumption and a linear output voltage within the wide range of capacitive transducer capacitance variation for the power supply voltage of 1.2 V was achieved. Conclusion/Recommendations: The output voltage of the circuit varied linearly with the variation of capacitive transducer capacitance variation. The improved converter was compact and robust for integration into capacitive measuring systems and suitable for use in environment that making use of higher frequency band.

  5. Molecular Aspects of Capacitation

    OpenAIRE

    Gulfidan Zulfikaroglu; Hulya Ozgur; Sait Polaturkey

    2010-01-01

    Male and female gamets are derived from the primordial germ cells, which migrate from the wall of the yolk sac toward the developing gonads. Following a series of mitotic divisions these cells increase in number at the gonads. The primordial germ cells differentiate into spermatogonia and take the form of mature spermatozoa after spermotogensis and spermotogenesis at puberty. Capacitation is the reaction, which includes all of the molecular and physiological events of mature sperm to gain the...

  6. Electrical capacitance clearanceometer

    Science.gov (United States)

    Hester, Norbert J. (Inventor); Hornbeck, Charles E. (Inventor); Young, Joseph C. (Inventor)

    1992-01-01

    A hot gas turbine engine capacitive probe clearanceometer is employed to measure the clearance gap or distance between blade tips on a rotor wheel and its confining casing under operating conditions. A braze sealed tip of the probe carries a capacitor electrode which is electrically connected to an electrical inductor within the probe which is inserted into a turbine casing to position its electrode at the inner surface of the casing. Electrical power is supplied through a voltage controlled variable frequency oscillator having a tuned circuit in which the probe is a component. The oscillator signal is modulated by a change in electrical capacitance between the probe electrode and a passing blade tip surface while an automatic feedback correction circuit corrects oscillator signal drift. A change in distance between a blade tip and the probe electrode is a change in capacitance therebetween which frequency modulates the oscillator signal. The modulated oscillator signal which is then processed through a phase detector and related circuitry to provide an electrical signal is proportional to the clearance gap.

  7. Capacitance of circular patch resonator

    Energy Technology Data Exchange (ETDEWEB)

    Miano, G.; Verolino, L. [Dip. di Ingegneria Elettrica, Ist. Nazionale di Fisica Nucleare, Naples (Italy); Panariello, G. [Dip. di Ingegneria Elettronica, Naples (Italy); Vaccaro, V.G. [Ist. Nazionale di Fisica Nucleare, Naples (Italy). Dipt. di Scienze Fisiche

    1995-11-01

    In this paper the capacitance of the circular microstrip patch resonator is computed. It is shown that the electrostatic problem can be formulated as a system of dual integral equations, and the most interesting techniques of solutions of these systems are reviewed. Some useful approximated formulas for the capacitance are derived and plots of the capacitance are finally given in a wide range of dielectric constants.

  8. Improved Capacitive Liquid Sensor

    Science.gov (United States)

    Waldman, Francis A.

    1992-01-01

    Improved capacitive sensor used to detect presence and/or measure thickness of layer of liquid. Electrical impedance or admittance of sensor measured at prescribed frequency, and thickness of liquid inferred from predetermined theoretical or experimental relationship between impedance and thickness. Sensor is basically a three-terminal device. Features interdigitated driving and sensing electrodes and peripheral coplanar ground electrode that reduces parasitic effects. Patent-pending because first to utilize ground plane as "shunting" electrode. System less expensive than infrared, microwave, or refractive-index systems. Sensor successfully evaluated in commercial production plants to characterize emulsions, slurries, and solutions.

  9. Programmable electronic synthesized capacitance

    Science.gov (United States)

    Kleinberg, Leonard L. (Inventor)

    1987-01-01

    A predetermined and variable synthesized capacitance which may be incorporated into the resonant portion of an electronic oscillator for the purpose of tuning the oscillator comprises a programmable operational amplifier circuit. The operational amplifier circuit has its output connected to its inverting input, in a follower configuration, by a network which is low impedance at the operational frequency of the circuit. The output of the operational amplifier is also connected to the noninverting input by a capacitor. The noninverting input appears as a synthesized capacitance which may be varied with a variation in gain-bandwidth product of the operational amplifier circuit. The gain-bandwidth product may, in turn, be varied with a variation in input set current with a digital to analog converter whose output is varied with a command word. The output impedance of the circuit may also be varied by the output set current. This circuit may provide very small ranges in oscillator frequency with relatively large control voltages unaffected by noise.

  10. A novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances

    Institute of Scientific and Technical Information of China (English)

    Dong Linxi; Chen Jindan; Yan Haixia; Huo Weihong; Li Yongjie; Sun Lingling

    2009-01-01

    The comb capacitances fabricated by deep reactive ion etching (RIE) process have high aspect ratio which is usually smaller than 30 : 1 for the complicated process factors, and the combs are usually not parallel due to the well-known micro-loading effect and other process factors, which restricts the increase of the seismic mass by increasing the thickness of comb to reduce the thermal mechanical noise and the decrease of the gap of the comb capacitances for increasing the sensitive capacitance to reduce the electrical noise. Aiming at the disadvantage of the deep RIE, a novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances is developed. One part of sensing of inertial signal of the micro-accelerometer is by the grid strip capacitances whose overlapping area is variable and which do not have the non-parallel plate's effect caused by the deep RIE process. Another part is by the sensing gap alterable capacitances whose gap between combs can be reduced by the actuators. The designed initial gap of the alterable comb capacitances is relatively large to depress the effect of the maximum aspect ratio (30 : 1) of deep RIE process. The initial gap of the capacitance of the actuator is smaller than the one of the comb capacitances. The difference between the two gaps is the initial gap of the sensitive capacitor. The designed structure depresses greatly the requirement of deep RIE process. The effects of non-parallel combs on the accelerometer are also analyzed. The characteristics of the micro-accelerometer are discussed by field emission microscopy (FEM) tool ANSYS. The tested devices based on slide-film damping effect are fabricated, and the tested quality factor is 514, which shows that grid strip capacitance design can partly improve the resolution and also prove the feasibility of the designed silicon-glass anodically bonding process.

  11. Calcium - urine

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003603.htm Calcium - urine To use the sharing features on this ... enable JavaScript. This test measures the amount of calcium in urine. All cells need calcium in order ...

  12. Calcium supplements

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

  13. Optimal pricing of capacitated networks

    NARCIS (Netherlands)

    Grigoriev, Alexander; Loon, van Joyce; Sitters, René; Uetz, Marc

    2009-01-01

    We address the algorithmic complexity of a profit maximization problem in capacitated, undirected networks. We are asked to price a set of $m$ capacitated network links to serve a set of $n$ potential customers. Each customer is interested in purchasing a network connection that is specified by a si

  14. Activation of calcium-sensing receptor increases TRPC3 expression in rat cardiomyocytes

    International Nuclear Information System (INIS)

    Research highlights: → Calcium-sensing receptor (CaR) activation stimulates TRP channels. → CaR promoted transient receptor potential C3 (TRPC3) expression. → Adult rat ventricular myocytes display capacitative calcium entry (CCE), which was operated by TRPCs. → TRPC channels activation induced by CaR activator sustained the increased [Ca2+]i to evoke cardiomyocytes apoptosis. -- Abstract: Transient receptor potential (TRP) channels are expressed in cardiomyocytes, which gate a type of influx of extracellular calcium, the capacitative calcium entry. TRP channels play a role in mediating Ca2+ overload in the heart. Calcium-sensing receptors (CaR) are also expressed in rat cardiac tissue and promote the apoptosis of cardiomyocytes by Ca2+ overload. However, data about the link between CaR and TRP channels in rat heart are few. In this study, reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting were used to examine the expression of the TRP canonical proteins TRPC1 and TRPC3 in adult and neonatal rat cardiomyocytes. Laser scan confocal microscopy was used to detect intracellular [Ca2+]i levels in isolated adult rat ventricular myocytes. The results showed that, in adult rat cardiomyocytes, the depletion of Ca2+ stores in the endoplasmic/sarcoplasmic reticulum (ER/SR) by thapsigargin induced a transient increase in [Ca2+]i in the absence of [Ca2+]o and the subsequent restoration of [Ca2+]o sustained the increased [Ca2+]i for a few minutes, whereas, the persisting elevation of [Ca2+]i was reduced in the presence of the TRPC inhibitor SKF96365. The stimulation of CaR by its activator gadolinium chloride (GdCl3) or spermine also resulted in the same effect and the duration of [Ca2+]i increase was also shortened in the absence of [Ca2+]o. In adult and neonatal rat cardiomyocytes, GdCl3 increased the expression of TRPC3 mRNA and protein, which were reversed by SKF96365 but not by inhibitors of the L-type channels and the Na+/Ca2+ exchangers

  15. Activation of calcium-sensing receptor increases TRPC3 expression in rat cardiomyocytes

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Shan-Li [Department of Clinical Laboratory, The Second Affiliated Hospital of Harbin Medical University, Harbin 150086 (China); Sun, Ming-Rui [Department of Pharmacology, Qiqihaer Medical College, Qiqihaer 160001 (China); Li, Ting-Ting; Yin, Xin [Department of Clinical Laboratory, The Second Affiliated Hospital of Harbin Medical University, Harbin 150086 (China); Xu, Chang-Qing [Department of Pathophysiology, Harbin Medical University, Harbin 150086 (China); Sun, Yi-Hua, E-mail: syh200415@126.com [Department of Clinical Laboratory, The Second Affiliated Hospital of Harbin Medical University, Harbin 150086 (China)

    2011-03-11

    Research highlights: {yields} Calcium-sensing receptor (CaR) activation stimulates TRP channels. {yields} CaR promoted transient receptor potential C3 (TRPC3) expression. {yields} Adult rat ventricular myocytes display capacitative calcium entry (CCE), which was operated by TRPCs. {yields} TRPC channels activation induced by CaR activator sustained the increased [Ca{sup 2+}]{sub i} to evoke cardiomyocytes apoptosis. -- Abstract: Transient receptor potential (TRP) channels are expressed in cardiomyocytes, which gate a type of influx of extracellular calcium, the capacitative calcium entry. TRP channels play a role in mediating Ca{sup 2+} overload in the heart. Calcium-sensing receptors (CaR) are also expressed in rat cardiac tissue and promote the apoptosis of cardiomyocytes by Ca{sup 2+} overload. However, data about the link between CaR and TRP channels in rat heart are few. In this study, reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting were used to examine the expression of the TRP canonical proteins TRPC1 and TRPC3 in adult and neonatal rat cardiomyocytes. Laser scan confocal microscopy was used to detect intracellular [Ca{sup 2+}]{sub i} levels in isolated adult rat ventricular myocytes. The results showed that, in adult rat cardiomyocytes, the depletion of Ca{sup 2+} stores in the endoplasmic/sarcoplasmic reticulum (ER/SR) by thapsigargin induced a transient increase in [Ca{sup 2+}]{sub i} in the absence of [Ca{sup 2+}]{sub o} and the subsequent restoration of [Ca{sup 2+}]{sub o} sustained the increased [Ca{sup 2+}]{sub i} for a few minutes, whereas, the persisting elevation of [Ca{sup 2+}]{sub i} was reduced in the presence of the TRPC inhibitor SKF96365. The stimulation of CaR by its activator gadolinium chloride (GdCl{sub 3}) or spermine also resulted in the same effect and the duration of [Ca{sup 2+}]{sub i} increase was also shortened in the absence of [Ca{sup 2+}]{sub o}. In adult and neonatal rat cardiomyocytes, GdCl{sub 3

  16. Entry and incumbent innovation

    OpenAIRE

    Weinschenk, Philipp

    2010-01-01

    We explore how the threat of entry influences the innovation activity of an incumbent. We show that the incumbent’s investment is hump-shaped in the entry threat. When the entry threat is small and increases, the incumbent invests more to deter entry, or to make it unlikely. This is due to the entry deterrence effect. However, when the threat becomes huge, entry can no longer profitably be deterred or made unlikely and the investment becomes small. Then the Schumpeterian effect dominates. The...

  17. Entry Modes of Starbucks

    OpenAIRE

    Santamaría Sotillo, Beatriz; Ni, Shuang

    2008-01-01

    Topic:When an MNC seeks to enter a foreign country, it must choose the most appropriate entry mode for that specific market, such as exporting, licensing, a turnkey project, franchising, joint ventures or wholly-owned subsidiaries. There are many factors which affect the choice of entry modes. Influential factors contributing to the entry mode decision can have different degrees of impact for each particular country. As a consequence, an MNC has to use different entry modes in order to adapt ...

  18. Capacitive deionization system

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, J. H., LLNL

    1996-10-01

    The new capacitive deionization system (CDI) removes ions, contaminants impurities from water and other aqueous process streams, and further selectively places the removed ions back into solution during regeneration. It provides a separation process that does not utilize chemical regeneration processes, and thus significantly reduces or completely eliminates secondary wastes associated with the operation of ion exchange resins. In the CDI, electrolyte flows in open channels formed between adjacent electrodes, and consequently the pressure drop is much lower than conventional separation processes. The fluid flow can be gravity fed through these open channels, and does not require membranes. This feature represents a significant advantage over the conventional reverse osmosis systems which include water permeable cellulose acetate membranes, and over the electrodialysis systems which require expensive and exotic ion exchange membranes. The CDI is adaptable for use in a wide variety of commercial applications, including domestic water softening, industrial water softening, waste water purification, sea water desalination, treatment of nuclear and aqueous wastes, treatment of boiler water in nuclear and fossil power plants, production of high-purity water for semiconductor processing, and removal of salt from water for agricultural irrigation. CDI accomplishes this removal of impurities by a variety of mechanisms, but predominantly by electrostatic removal of organic and inorganic ions from water or any other dielectric solvent.

  19. Efficiency of Capacitively Loaded Converters

    DEFF Research Database (Denmark)

    Andersen, Thomas; Huang, Lina; Andersen, Michael A. E.;

    2012-01-01

    is introduced as a definition of efficiency. The calculated and measured efficiency curves for charging DEAP actuator, polypropylene film capacitor and X7R MLCC are provided and compared. The attention has to be paid for the voltage dependent capacitive load, like X7R MLCC, when evaluating the charging......This paper explores the characteristic of capacitance versus voltage for dielectric electro active polymer (DEAP) actuator, 2kV polypropylene film capacitor as well as 3kV X7R multi layer ceramic capacitor (MLCC) at the beginning. An energy efficiency for capacitively loaded converters...... efficiency of converter. Based on the capacitancevoltage curve, the correct capacitance should be chosen when calculating the stored energy; otherwise misleading optimistic efficiency can always be obtained. Actually, when DEAP actuator is not available at the early developing stage, the voltage independent...

  20. Capacitive Position Sensor For Accelerometer

    Science.gov (United States)

    Vanzandt, Thomas R.; Kaiser, William J.; Kenny, Thomas W.

    1995-01-01

    Capacitive position sensor measures displacement of proof mass in prototype accelerometer described in "Single-Crystal Springs for Accelerometers" (NPO-18795). Sensor is ultrasensitive, miniature device operating at ultra-high frequency and described in more detail in "Ultra-High-Frequency Capacitive Displacement Sensor," (NPO-18675). Advances in design and fabrication of prototype accelerometer also applicable to magnetometers and other sensors in which sensed quantities measured in terms of deflections of small springs.

  1. The concept of chemical capacitance, A critique.

    OpenAIRE

    Trissl, H. W.

    1981-01-01

    The concept of chemical capacitance as introduced by Hong and Mauzerall (Proc. Natl. Acad. Sci. U.S.A. 1974. 71:1564) is critically reexamined. This novel capacitance was introduced to explain the time-course of flash-induced photocurrents observed in lipid bilayer membranes containing porphyrins. According to Hong and Mauzerall, the chemical capacitance results from a combination of three fundamental capacitances: the geometric membrane capacitance and the two interfacial double layer capaci...

  2. Bioenergetics of Mammalian Sperm Capacitation

    Directory of Open Access Journals (Sweden)

    Alessandra Ferramosca

    2014-01-01

    Full Text Available After ejaculation, the mammalian male gamete must undergo the capacitation process, which is a prerequisite for egg fertilization. The bioenergetics of sperm capacitation is poorly understood despite its fundamental role in sustaining the biochemical and molecular events occurring during gamete activation. Glycolysis and mitochondrial oxidative phosphorylation (OXPHOS are the two major metabolic pathways producing ATP which is the primary source of energy for spermatozoa. Since recent data suggest that spermatozoa have the ability to use different metabolic substrates, the main aim of this work is to present a broad overview of the current knowledge on the energy-producing metabolic pathways operating inside sperm mitochondria during capacitation in different mammalian species. Metabolism of glucose and of other energetic substrates, such as pyruvate, lactate, and citrate, is critically analyzed. Such knowledge, besides its obvious importance for basic science, could eventually translate into the development of novel strategies for treatment of male infertility, artificial reproduction, and sperm selection methods.

  3. Improving capacitance/damping ratio in a capacitive MEMS transducer

    International Nuclear Information System (INIS)

    Damping forces play an important role in capacitive MEMS (microelectromechanical systems) behavior, and typical damper design (parallel-plates) cannot address the design conflict between increase in electrical capacitance and damping reduction. Squeeze-film damping in in-plane parallel-plate MEMS is discussed here and a novel damper geometry for gap-varying parallel-plates is introduced and used to increase the capacitance/damping ratio. The new geometry is compared with a typical parallel-plate design for an silicon-on-insulator process (25 µm thick) and experimental data shows an approximate 25% to 50% reduction for the damping coefficient in structures with 500 µm long dampers (for a gap variation between 0.75 and 3.75 µm), in agreement with computational fluid dynamics simulations, without significantly affecting the capacitance value (∼4% reduction). Preliminary simulations to study the role of the different geometric parameters involved in the improved geometry are also performed and reveal that the channel width is the most critical value for effective damping reduction. (paper)

  4. Water desalination via capacitive deionization

    NARCIS (Netherlands)

    Suss, M.E.; Porada, S.; Sun, X.; Biesheuvel, P.M.; Yoon, J.; Presser, V.

    2015-01-01

    Capacitive deionization (CDI) is an emerging technology for the facile removal of charged ionic species from aqueous solutions, and is currently being widely explored for water desalination applications. The technology is based on ion electrosorption at the surface of a pair of electrically charg

  5. Driven shielding capacitive proximity sensor

    Science.gov (United States)

    Vranish, John M. (Inventor); McConnell, Robert L. (Inventor)

    2000-01-01

    A capacitive proximity sensing element, backed by a reflector driven at the same voltage as and in phase with the sensor, is used to reflect the field lines away from a grounded robot arm towards an intruding object, thus dramatically increasing the sensor's range and sensitivity.

  6. Voltage Dependence of Supercapacitor Capacitance

    Directory of Open Access Journals (Sweden)

    Szewczyk Arkadiusz

    2016-09-01

    Full Text Available Electronic Double-Layer Capacitors (EDLC, called Supercapacitors (SC, are electronic devices that are capable to store a relatively high amount of energy in a small volume comparing to other types of capacitors. They are composed of an activated carbon layer and electrolyte solution. The charge is stored on electrodes, forming the Helmholtz layer, and in electrolyte. The capacitance of supercapacitor is voltage- dependent. We propose an experimental method, based on monitoring of charging and discharging a supercapacitor, which enables to evaluate the charge in an SC structure as well as the Capacitance-Voltage (C-V dependence. The measurement setup, method and experimental results of charging/discharging commercially available supercapacitors in various voltage and current conditions are presented. The total charge stored in an SC structure is proportional to the square of voltage at SC electrodes while the charge on electrodes increases linearly with the voltage on SC electrodes. The Helmholtz capacitance increases linearly with the voltage bias while a sublinear increase of total capacitance was found. The voltage on SC increases after the discharge of electrodes due to diffusion of charges from the electrolyte to the electrodes. We have found that the recovery voltage value is linearly proportional to the initial bias voltage value.

  7. Capacitive Proximity Sensor Has Longer Range

    Science.gov (United States)

    Vranish, John M.

    1992-01-01

    Capacitive proximity sensor on robot arm detects nearby object via capacitive effect of object on frequency of oscillator. Sensing element part of oscillator circuit operating at about 20 kHz. Total capacitance between sensing element and ground constitutes tuning capacitance of oscillator. Sensor circuit includes shield driven by replica of alternating voltage applied to sensing element. Driven shield concentrates sensing electrostatic field in exterior region to enhance sensitivity to object. Sensitivity and dynamic range has corresponding 12-to-1 improvement.

  8. Active Targets For Capacitive Proximity Sensors

    Science.gov (United States)

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Lightweight, low-power active targets devised for use with improved capacitive proximity sensors described in "Capacitive Proximity Sensor Has Longer Range" (GSC-13377), and "Capacitive Proximity Sensors With Additional Driven Shields" (GSC-13475). Active targets are short-distance electrostatic beacons; they generate known alternating electro-static fields used for alignment and/or to measure distances.

  9. Osteoblasts detect pericellular calcium concentration increase via neomycin-sensitive voltage gated calcium channels.

    Science.gov (United States)

    Sun, Xuanhao; Kishore, Vipuil; Fites, Kateri; Akkus, Ozan

    2012-11-01

    The mechanisms underlying the detection of critically loaded or micro-damaged regions of bone by bone cells are still a matter of debate. Our previous studies showed that calcium efflux originates from pre-failure regions of bone matrix and MC3T3-E1 osteoblasts respond to such efflux by an increase in the intracellular calcium concentration. The mechanisms by which the intracellular calcium concentration increases in response to an increase in the pericellular calcium concentration are unknown. Elevation of the intracellular calcium may occur via release from the internal calcium stores of the cell and/or via the membrane bound channels. The current study applied a wide range of pharmaceutical inhibitors to identify the calcium entry pathways involved in the process: internal calcium release from endoplasmic reticulum (ER, inhibited by thapsigargin and TMB-8), calcium receptor (CaSR, inhibited by calhex), stretch-activated calcium channel (SACC, inhibited by gadolinium), voltage-gated calcium channels (VGCC, inhibited by nifedipine, verapamil, neomycin, and ω-conotoxin), and calcium-induced-calcium-release channel (CICRC, inhibited by ryanodine and dantrolene). These inhibitors were screened for their effectiveness to block intracellular calcium increase by using a concentration gradient induced calcium efflux model which mimics calcium diffusion from the basal aspect of cells. The inhibitor(s) which reduced the intracellular calcium response was further tested on osteoblasts seeded on mechanically loaded notched cortical bone wafers undergoing damage. The results showed that only neomycin reduced the intracellular calcium response in osteoblasts, by 27%, upon extracellular calcium stimulus induced by concentration gradient. The inhibitory effect of neomycin was more pronounced (75% reduction in maximum fluorescence) for osteoblasts seeded on notched cortical bone wafers loaded mechanically to damaging load levels. These results imply that the increase in

  10. Calcium-sensing receptor: a key target for extracellular calcium signaling in neurons

    Directory of Open Access Journals (Sweden)

    Brian L Jones

    2016-03-01

    Full Text Available Though both clinicians and scientists have long recognized the influence of extracellular calcium on the function of muscle and nervous tissue, recent insights reveal that the mechanisms allowing changes in extracellular calcium to alter cellular excitability have been incompletely understood. For many years the effects of calcium on neuronal signaling were explained only in terms of calcium entry through voltage-gated calcium channels and biophysical charge screening. More recently however, it has been recognized that the calcium-sensing receptor is prevalent in the nervous system and regulates synaptic transmission and neuronal activity via multiple signaling pathways. Here we review the multiplicity of mechanisms by which changes in extracellular calcium alter neuronal signaling and propose that multiple mechanisms are required to describe the full range of experimental observations.

  11. Effects of stray capacitance to ground in bipolar water impedance measurements based on capacitive electrodes

    OpenAIRE

    Pallàs Areny, Ramon; Aliau Bonet, Carles

    2015-01-01

    Liquid impedance measurements based on capacitive (or contactless) electrodes Overcome electrode polarization problems but are affected by stray capacitance from the material being measured to ground, the same as measurements with direct-contact electrodes. This study shows that the effects of that capacitance depend on the impedance being measured and for bipolar impedance measurements they increase when the ratio between that stray capacitance and lectrode capacitance increases.

  12. Entry Threat in Duopoly

    OpenAIRE

    Peitz, Martin

    1996-01-01

    Abstract: An oligopolistic market with vertical product differentiation is parametrized in cost parameters. This allows me to study the impact of the technology of the firms (cost parameters) on market structure, conduct, and performance. Firms which differ only by the order of the sequential move to choose a quality use sophisticated entry deterring or entry accomodating strategies. I show that infinitesimal changes in the cost parameters can generate discontinuities in market profits. In pa...

  13. Full-bridge capacitive extensometer

    Science.gov (United States)

    Peters, Randall D.

    1993-08-01

    Capacitive transducers have proven to be very effective sensors of small displacements, because of inherent stability and noninvasive high resolution. The most versatile ones have been those of a differential type, in which two elements are altered in opposite directions in response to change of the system parameter being monitored. Oftentimes, this differential pair has been incorporated into a bridge circuit, which is a useful means for employing synchronous detection to improve signal to noise ratios. Unlike previous differential capacitive dilatometers which used only two active capacitors, the present sensor is a full-bridge type, which is well suited to measuring low-level thermal expansions. This analog sensor is capable of 0.1 μm resolution anywhere within a range of several centimeters, with a linearity of 0.1%. Its user friendly output can be put on a strip chart recorder or directed to a computer for sophisticated data analysis.

  14. Quantum capacitance in topological insulators.

    Science.gov (United States)

    Xiu, Faxian; Meyer, Nicholas; Kou, Xufeng; He, Liang; Lang, Murong; Wang, Yong; Yu, Xinxin; Fedorov, Alexei V; Zou, Jin; Wang, Kang L

    2012-01-01

    Topological insulators show unique properties resulting from massless, Dirac-like surface states that are protected by time-reversal symmetry. Theory predicts that the surface states exhibit a quantum spin Hall effect with counter-propagating electrons carrying opposite spins in the absence of an external magnetic field. However, to date, the revelation of these states through conventional transport measurements remains a significant challenge owing to the predominance of bulk carriers. Here, we report on an experimental observation of Shubnikov-de Haas oscillations in quantum capacitance measurements, which originate from topological helical states. Unlike the traditional transport approach, the quantum capacitance measurements are remarkably alleviated from bulk interference at high excitation frequencies, thus enabling a distinction between the surface and bulk. We also demonstrate easy access to the surface states at relatively high temperatures up to 60 K. Our approach may eventually facilitate an exciting exploration of exotic topological properties at room temperature.

  15. Water desalination via capacitive deionization

    OpenAIRE

    Suss, M. E.; Porada, S.; Sun, X.; Biesheuvel, P. M.; Yoon, J.; Presser, V.

    2015-01-01

    Capacitive deionization (CDI) is an emerging technology for the facile removal of charged ionic species from aqueous solutions, and is currently being widely explored for water desalination applications. The technology is based on ion electrosorption at the surface of a pair of electrically charged electrodes, commonly composed of highly porous carbon materials. The CDI community has grown exponentially over the past decade, driving tremendous advances via new cell architectures and system de...

  16. Capacitive de-ionization electrode

    Energy Technology Data Exchange (ETDEWEB)

    Daily, III, William D.

    2013-03-19

    An electrode "cell" for use in a capacitive deionization (CDI) reactor consists of the electrode support structure, a non-reactive conductive material, the electrode accompaniment or substrate and a flow through screen/separator. These "layers" are repeated and the electrodes are sealed together with gaskets between two end plates to create stacked sets of alternating anode and cathode electrodes in the CDI reactor.

  17. Detection of cooling-induced membrane changes in the response of boar sperm to capacitating conditions.

    Science.gov (United States)

    Petrunkina, Anna M; Volker, Gabriele; Weitze, Karl-Fritz; Beyerbach, Martin; Töpfer-Petersen, Edda; Waberski, Dagmar

    2005-05-01

    There is a need for methods of rapid and sensitive sperm function assessment. As spermatozoa are not able to fertilize an oocyte before having undergone a series of complex physiological changes collectively called capacitation, it is logical to assess sperm function under fertilizing conditions in vitro. In this study, the responsiveness of sperm to capacitating conditions in vitro was monitored by changes in sperm response to ionophore and by changes in the amount of intracellular calcium ions in stored boar semen. Boar semen was diluted at 32 and 20 degrees C and stored for 24 and 72 h at 16 and 10 degrees C. Ionophore-induced changes and increased intracellular calcium ion content in boar spermatozoa were recorded by flow cytometry and found to progress as a function of time during incubation under capacitating conditions. All responsiveness parameters (increases in proportions of membrane-defective spermatozoa, acrosome-reacted spermatozoa, and cells with high intracellular calcium levels) were shown to be sensitive to subtle physiological changes occurring at low storage temperatures. The initial levels of sperm with a high calcium content were higher in semen stored at 10 degrees C, but the accumulation of internal calcium was lower than in semen stored at 16 degrees C. The loss of membrane integrity and increase in the proportion of acrosome-reacted cells were higher in semen stored at 10 degrees C. Dilution at 20 degrees C had no negative effect on membrane integrity or responsiveness to capacitating conditions. There was no significant difference between semen stored for 24 and 72 h in terms of membrane integrity, acrosome reaction, and intracellular calcium after capacitation treatment. However, dynamics of cell death and acrosome reaction in response to capacitating conditions were somewhat accelerated after 72 h storage, especially in semen stored at 10 degrees C. It can be concluded that the simultaneous use of the sperm membrane responsiveness and

  18. Redox regulation of mammalian sperm capacitation

    Directory of Open Access Journals (Sweden)

    Cristian O′Flaherty

    2015-01-01

    Full Text Available Capacitation is a series of morphological and metabolic changes necessary for the spermatozoon to achieve fertilizing ability. One of the earlier happenings during mammalian sperm capacitation is the production of reactive oxygen species (ROS that will trigger and regulate a series of events including protein phosphorylation, in a time-dependent fashion. The identity of the sperm oxidase responsible for the production of ROS involved in capacitation is still elusive, and several candidates are discussed in this review. Interestingly, ROS-induced ROS formation has been described during human sperm capacitation. Redox signaling during capacitation is associated with changes in thiol groups of proteins located on the plasma membrane and subcellular compartments of the spermatozoon. Both, oxidation of thiols forming disulfide bridges and the increase on thiol content are necessary to regulate different sperm proteins associated with capacitation. Reducing equivalents such as NADH and NADPH are necessary to support capacitation in many species including humans. Lactate dehydrogenase, glucose-6-phospohate dehydrogenase, and isocitrate dehydrogenase are responsible in supplying NAD (P H for sperm capacitation. Peroxiredoxins (PRDXs are newly described enzymes with antioxidant properties that can protect mammalian spermatozoa; however, they are also candidates for assuring the regulation of redox signaling required for sperm capacitation. The dysregulation of PRDXs and of enzymes needed for their reactivation such as thioredoxin/thioredoxin reductase system and glutathione-S-transferases impairs sperm motility, capacitation, and promotes DNA damage in spermatozoa leading to male infertility.

  19. An approach to evaluate capacitance, capacitive reactance and resistance of pivoted pads of a thrust bearing

    Science.gov (United States)

    Prashad, Har

    1992-07-01

    A theoretical approach is developed for determining the capacitance and active resistance between the interacting surfaces of pivoted pads and thrust collar, under different conditions of operation. It is shown that resistance and capacitive reactance of a thrust bearing decrease with the number of pads times the values of these parameters for an individual pad, and that capacitance increases with the number of pads times the capacitance of an individual pad. The analysis presented has a potential to diagnose the behavior of pivoted pad thrust bearings with the angle of tilt and the ratio of film thickness at the leading to trailing edge, by determining the variation of capacitance, resistance, and capacitive reactance.

  20. Role of ions and ion channels in capacitation and acrosome reaction of spermatozoa

    Institute of Scientific and Technical Information of China (English)

    SharadBPurohit; MaliniLaloraya; G.pradeepkumar

    1999-01-01

    Capacitation and acrosome reaction are important prerequisites of the fertilization process. Capacitation is a highlycomplex phenomenon occurring in the female genital tract, rendering the spermatozoa capable of binding and fusionwith the oocyte. During capacitation various biochemical and biophysical changes occur in the spermatozoa and thespermatozoal membranes. Ions and ion channels also play important roles in governing the process of capacitation bychanging the fluxes of different ions which in turn controls various characteristics of capacitated spermatozoa. Alongwith the mobilization of ions the generation of free radicals and efflux of cholesterol also plays an impo~.nt role in thecapacitation state of the spermatozoa. The generation of free radical and efflux of cholesterol change the mechano-dynamic properties of the membrane by oxidation of the polyunsaturated lipids and by generating the cholesterol freepatches. The process of capacitation renders the spermatozoa responsive to the inducers of the acrosome reaction. Theglycoprotein zona pellucida 3 (ZP3) of the egg coat zona pellucida is the potent physiological stimulator of the acro-some reaction; progesterone, a major component of the follicular fluid, is also an inducer of the acrosome reaction.The inducers of the acrosome reaction cause the activation of the various ion-channels leading to high influxes of calci-um, sodium and bicarbonate. The efflux of cholesterol during the process of capacitation alters the permeability of themembrane to the ions and generate areas which are prone to fusion and ve.siculation process during the acrosome reactioa. this review focuses mainly on effects of the ion and ion-channels, free radicals, and membrane fluidity changesduring the process of capacitation and acrosome reaction.

  1. Calcium-dependent and calcium-sensitizing pathways in the mature and immature ductus arteriosus.

    Science.gov (United States)

    Clyman, Ronald I; Waleh, Nahid; Kajino, Hiroki; Roman, Christine; Mauray, Francoise

    2007-10-01

    Studies performed in sheep and baboons have shown that after birth, the normoxic muscle media of ductus arteriosus (DA) becomes profoundly hypoxic as it constricts and undergoes anatomic remodeling. We used isolated fetal lamb DA (pretreated with inhibitors of prostaglandin and nitric oxide production) to determine why the immature DA fails to remain tightly constricted during the hypoxic phase of remodeling. Under normoxic conditions, mature DA constricts to 70% of its maximal active tension (MAT). Half of its normoxic tension is due to Ca(2+) entry through calcium L-channels and store-operated calcium (SOC) channels. The other half is independent of extracellular Ca(2+) and is unaffected by inhibitors of sarcoplasmic reticulum (SR) Ca(2+) release (ryanodine) or reuptake [cyclopiazonic acid (CPA)]. The mature DA relaxes slightly during hypoxia (to 60% MAT) due to decreases in calcium L-channel-mediated Ca(2+) entry. Inhibitors of Rho kinase and tyrosine kinase inhibit both Ca(2+)-dependent and Ca(2+)-independent DA tension. Although Rho kinase activity may increase during gestation, immature DA develop lower tensions than mature DA, primarily because of differences in the way they process Ca(2+). Calcium L-channel expression increases with advancing gestation. Under normoxic conditions, differences in calcium L-channel-mediated Ca(2+) entry account for differences in tension between immature (60% MAT) and mature (70% MAT) DA. Under hypoxic conditions, differences in both calcium L-channel-dependent and calcium L-channel-independent Ca(2+) entry, account for differences in tension between immature (33% MAT) and mature (60% MAT) DA. Stimulation of Ca(2+) entry through reverse-mode Na(+)/Ca(2+) exchange or CPA-induced SOC channel activity constrict the DA and eliminate differences between immature and mature DA during both hypoxia and normoxia.

  2. Calcium Carbonate

    Science.gov (United States)

    ... before being swallowed; do not swallow them whole. Drink a full glass of water after taking either the regular or chewable tablets or capsules. Some liquid forms of calcium carbonate must be shaken well before use.Do not ...

  3. Calcium Calculator

    Science.gov (United States)

    ... Latvia - Lebanon - Libya - Lithuania - Luxembourg - Macedonia, Republic of - Malaysia - Malta - Mexico - Moldova - Morocco - Netherlands - New Zealand - Nigeria - ... and Statistics Popular content Calcium content of common foods What is Osteoporosis? The Board Introduction to Bone ...

  4. Calcium Electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha;

    2015-01-01

    BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p

  5. Time card entry system

    Energy Technology Data Exchange (ETDEWEB)

    Montierth, B.S.

    1996-05-01

    The Time Card Entry System was developed to interface with the DOE Headquarters Electronic Time and Attendance (ETA) system. It features pop-up window pick lists for Work Breakdown Structure Numbers and Hour Codes and has extensive processing that ensures that time and attendance reported by the employee fulfills US Government/OMB requirements before Timekeepers process the data at the end of the two week payroll cycle using ETA. Tours of Duty (e.g. ten hour day, four day week with Friday through Sunday off), established in the ETA system, are imported into the Time Card Entry System by the Timekeepers. An individual`s Tour of Duty establishes the basis for validation of time of day and number of hours worked per day. At the end of the two week cycle, data is exported by the Timekeepers from the Time Card Entry System into ETA data files.

  6. Flexible PVDF ferroelectric capacitive temperature sensor

    KAUST Repository

    Khan, Naveed

    2015-08-02

    In this paper, a capacitive temperature sensor based on polyvinylidene fluoride (PVDF) capacitor is explored. The PVDF capacitor is characterized below its Curie temperature. The capacitance of the PVDF capacitor changes vs temperature with a sensitivity of 16pF/°C. The linearity measurement of the capacitance-temperature relation shows less than 0.7°C error from a best fit straight line. An LC oscillator based temperature sensor is demonstrated based on this capacitor.

  7. Nucleotide Capacitance Calculation for DNA Sequencing

    OpenAIRE

    Lu, Jun-Qiang; Zhang, X.-G.

    2008-01-01

    Using a first-principles linear response theory, the capacitance of the DNA nucleotides, adenine, cytosine, guanine, and thymine, are calculated. The difference in the capacitance between the nucleotides is studied with respect to conformational distortion. The result suggests that although an alternate current capacitance measurement of a single-stranded DNA chain threaded through a nanogap electrode may not be sufficient to be used as a standalone method for rapid DNA sequencing, the capaci...

  8. Electrical Capacitance Volume Tomography: Design and Applications

    OpenAIRE

    Warsito Warsito; Liang-Shih Fan; Qussai Marashdeh; Fei Wang

    2010-01-01

    This article reports recent advances and progress in the field of electrical capacitance volume tomography (ECVT). ECVT, developed from the two-dimensional electrical capacitance tomography (ECT), is a promising non-intrusive imaging technology that can provide real-time three-dimensional images of the sensing domain. Images are reconstructed from capacitance measurements acquired by electrodes placed on the outside boundary of the testing vessel. In this article, a review of progress on capa...

  9. Electrochemical capacitance of a leaky nanocapacitor

    OpenAIRE

    Zhao, X; Guo, H; Wang, J.

    1999-01-01

    We report a detailed theoretical investigation on electrochemical capacitance of a nanoscale capacitor where there is a DC coupling between the two conductors. For this ``leaky'' quantum capacitor, we have derived general analytic expressions of the linear and second order nonlinear electrochemical capacitance within a first principles quantum theory in the discrete potential approximation. Linear and nonlinear capacitance coefficients are also derived in a self-consistent manner without the ...

  10. A mathematical model of T lymphocyte calcium dynamics derived from single transmembrane protein properties

    Directory of Open Access Journals (Sweden)

    Christine Dorothee Schmeitz

    2013-09-01

    Full Text Available Fate decision processes of T lymphocytes are crucial for health and disease. Whether a T lymphocyte is activated, divides, gets anergic or initiates apoptosis depends on extracellular triggers and intracellular signalling. Free cytosolic calcium dynamics plays an important role in this context. The relative contributions of store-derived calcium entry and calcium entry from extracellular space to T lymphocyte activation are still a matter of debate. Here we develop a quantitative mathematical model of T lymphocyte calcium dynamics in order to establish a tool which allows to disentangle cause-effect relationships between ion fluxes and observed calcium time courses. The model is based on single transmembrane protein characteristics which have been determined in independent experiments. This reduces the number of unknown parameters in the model to a minimum and ensures the predictive power of the model. Simulation results are subsequently used for an analysis of whole cell calcium dynamics measured under various experimental conditions. The model accounts for a variety of these conditions, which supports the suitability of the modelling approach. The simulation results suggest a model in which calcium dynamics dominantly relies on the opening of channels in calcium stores while calcium entry through calcium-release activated channels (CRAC is more associated with the maintenance of the T lymphocyte calcium levels and prevents the cell from calcium depletion. Our findings indicate that CRAC guarantees a long-term stable calcium level which is required for cell survival and sustained calcium enhancement.

  11. Dual Cryogenic Capacitive Density Sensor

    Science.gov (United States)

    Youngquist, Robert; Mata, Carlos; Vokrot, Peter; Cox, Robert

    2009-01-01

    A dual cryogenic capacitive density sensor has been developed. The device contains capacitive sensors that monitor two-phase cryogenic flow density to within 1% accuracy, which, if temperature were known, could be used to determine the ratio of liquid to gas in the line. Two of these density sensors, located a known distance apart, comprise the sensor, providing some information on the velocity of the flow. This sensor was constructed as a proposed mass flowmeter with high data acquisition rates. Without moving parts, this device is capable of detecting the density change within a two-phase cryogenic flow more than 100 times a second. Detection is enabled by a series of two sets of five parallel plates with stainless steel, cryogenically rated tubing. The parallel plates form the two capacitive sensors, which are measured by electrically isolated digital electronics. These capacitors monitor the dielectric of the flow essentially the density of the flow and can be used to determine (along with temperature) the ratio of cryogenic liquid to gas. Combining this information with the velocity of the flow can, with care, be used to approximate the total two-phase mass flow. The sensor can be operated at moderately high pressures and can be lowered into a cryogenic bath. The electronics have been substantially improved over the older sensors, incorporating a better microprocessor, elaborate ground loop protection and noise limiting circuitry, and reduced temperature sensitivity. At the time of this writing, this design has been bench tested at room temperature, but actual cryogenic tests are pending

  12. Capacitance enhancement via electrode patterning.

    Science.gov (United States)

    Ho, Tuan A; Striolo, Alberto

    2013-11-28

    The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties. PMID:24289370

  13. Exclusive Dealing and Entry

    OpenAIRE

    João Leão

    2008-01-01

    This paper examines the use of exclusive dealing agreements to prevent the entry of rival firms. An exclusive dealing agreement is a contract between a buyer and a seller where the buyer commits to buy a good exclusively from the seller. One main concern of the literature is to explain how an incumbent seller is able to persuade the buyers to sign an exclusive dealing agreement that deters the entry of a more efficient rival seller. We propose a new explanation when the buyers are downstream ...

  14. Detection of Telomerase Activity Using Capacitance Measurements

    Science.gov (United States)

    Kang, Bong Keun; Lee, Ri Mi; Choi, Ahmi; Jung, Hyo-Il; Yoo, Kyung-Hwa

    2007-03-01

    Telomerase activity has been found in about 85% cancer cells, while no activity observed in normal cells, so that telomerase has been proposed as a marker for cancer detection. Here, we describe electrical detection of telomerase activity using capacitance measurements. We have investigated the length dependence of capacitance on DNA solutions and found that the capacitance of DNA solutions were dependent on the DNA length. In addition, upon adding telomerase into the solution of telomeric substrate primer, the capacitance was observed to change as a function of time due to the telomeric elongation. These results suggest that this novel nanosensor may be used for rapid detection of telomerase activity.

  15. Module Eleven: Capacitance; Basic Electricity and Electronics Individualized Learning System.

    Science.gov (United States)

    Bureau of Naval Personnel, Washington, DC.

    In this module the student will learn about another circuit quantity, capacitance, and discover the effects of this component on circuit current, voltage, and power. The module is divided into seven lessons: the capacitor, theory of capacitance, total capacitance, RC (resistive-capacitive circuit) time constant, capacitive reactance, phase and…

  16. Capacitance Measurement with a Sigma Delta Converter for 3D Electrical Capacitance Tomography

    Science.gov (United States)

    Nurge, Mark

    2005-01-01

    This paper will explore suitability of a newly available capacitance to digital converter for use in a 3D Electrical Capacitance Tomography system. A switch design is presented along with circuitry needed to extend the range of the capacitance to digital converter. Results are then discussed for a 15+ hour drift and noise test.

  17. Altered calcium signaling following traumatic brain injury

    Directory of Open Access Journals (Sweden)

    John Thomas Weber

    2012-04-01

    Full Text Available Cell death and dysfunction after traumatic brain injury (TBI is caused by a primary phase, related to direct mechanical disruption of the brain, and a secondary phase which consists of delayed events initiated at the time of the physical insult. Arguably, the calcium ion contributes greatly to the delayed cell damage and death after TBI. A large, sustained influx of calcium into cells can initiate cell death signaling cascades, through activation of several degradative enzymes, such as proteases and endonucleases. However, a sustained level of intracellular free calcium is not necessarily lethal, but the specific route of calcium entry may couple calcium directly to cell death pathways. Other sources of calcium, such as intracellular calcium stores, can also contribute to cell damage. In addition, calcium-mediated signal transduction pathways in neurons may be perturbed following injury. These latter types of alterations may contribute to abnormal physiology in neurons that do not necessarily die after a traumatic episode. This review provides an overview of experimental evidence that has led to our current understanding of the role of calcium signaling in death and dysfunction following TBI.

  18. Capacitive Feedthroughs for Medical Implants

    Science.gov (United States)

    Grob, Sven; Tass, Peter A.; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging.

  19. Ultrahigh Temperature Capacitive Pressure Sensor

    Science.gov (United States)

    Harsh, Kevin

    2014-01-01

    Robust, miniaturized sensing systems are needed to improve performance, increase efficiency, and track system health status and failure modes of advanced propulsion systems. Because microsensors must operate in extremely harsh environments, there are many technical challenges involved in developing reliable systems. In addition to high temperatures and pressures, sensing systems are exposed to oxidation, corrosion, thermal shock, fatigue, fouling, and abrasive wear. In these harsh conditions, sensors must be able to withstand high flow rates, vibration, jet fuel, and exhaust. In order for existing and future aeropropulsion turbine engines to improve safety and reduce cost and emissions while controlling engine instabilities, more accurate and complete sensor information is necessary. High-temperature (300 to 1,350 C) capacitive pressure sensors are of particular interest due to their high measurement bandwidth and inherent suitability for wireless readout schemes. The objective of this project is to develop a capacitive pressure sensor based on silicon carbon nitride (SiCN), a new class of high-temperature ceramic materials, which possesses excellent mechanical and electric properties at temperatures up to 1,600 C.

  20. Energy-Efficient Capacitive-Sensor Interfaces

    NARCIS (Netherlands)

    Tan, Z.

    2013-01-01

    This thesis describes the theory, design and realization of energy-efficient capacitive-sensor interfaces that are dedicated to energy-constrained applications. The goal of this work is to explore energy-efficient capacitive-sensor interface design techniques both at the system and the circuit level

  1. Dissecting graphene capacitance in electrochemical cell

    International Nuclear Information System (INIS)

    Quantum capacitance of graphene plays a significant role for graphene's applications in electrochemical devices and sensors, while the determination of these basic characters of Dirac point, Fermi energy, quantum capacitance, etc is still a subject of considerable debate in both experiments and simulations. Here, we report joint first-principles/continuum calculations (JFPCCs) on a monolayer graphene electrode immersed in an electrolyte coupled with a reference electrode under an applied potential. The JFPCCs gave the Fermi level, charge density on graphene, Dirac point energy, electrostatic potential, electric double layer etc as a function of the applied potential with respect to the reference electrode. These results revealed the strongly coupled relationship between Fermi level change and Dirac point shift in electrochemical cell. The total capacitance of the electrochemical cell was dissected into the quantum capacitance of the graphene electrode and the capacitance of the electric double layer. Furthermore, simple and analytic formulas were proposed for the three capacitances, which predicted, in sufficient accuracy, the behavior of capacitance versus potential. These findings deepen the understanding of quantum capacitance of graphene, which will stimulate novel experimental and theoretical studies and boost the applications of graphene in electrochemical and energy areas

  2. Quantum capacitance of the monolayer graphene

    OpenAIRE

    Cheremisin, M. V.

    2012-01-01

    The quantum capacitance of the monolayer graphene for arbitrary carrier density, magnetic field and temperature is found. The density dependence of the quantum capacitance is analyzed for magnetic field(temperature) is fixed(varied) and vice versa. The theory is compared with the experimental data.

  3. Capacitance densitometer for flow regime identification

    Science.gov (United States)

    Shipp, Jr., Roy L.

    1978-01-01

    This invention relates to a capacitance densitometer for determining the flow regime of a two-phase flow system. A two-element capacitance densitometer is used in conjunction with a conventional single-beam gamma densitometer to unambiguously identify the prevailing flow regime and the average density of a flowing fluid.

  4. Capacitance-coupled wiper increases potentiometer life

    Science.gov (United States)

    Dimeff, J.

    1968-01-01

    Capacitively-coupled wiper reduces the friction between the sliding contact and the potentiometer element in conventional potentiometers. A small preamplifier employed close to the wiper reduces errors caused by output cable capacitance. The device is friction free with resultant low wear and has high speed and high resolution.

  5. Deployable Entry-system Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Deployable Entry-system ProjecT (ADEPT) will develop requirements for the ADEPT flight test.  Prior entry systems used high mass thermal protection...

  6. Conductivity Effect on the Capacitance Measurement of a Parallel-Plate Capacitive Sensor System

    Directory of Open Access Journals (Sweden)

    Peyman Azimi

    2011-01-01

    Full Text Available In this article design and operation of a parallel-plate capacitive sensor based on the dielectric capacitance and conductance change of the gap medium is reported. The designed system was used to determine characteristics of different water liquids as a result of the capacitance variations. The air gap capacitance is measured and then by filling the gap with a liquid the capacitance is monitored for different liquids. Proposed sensor is used for the distilled, tap, boiled, and salt water measurements and the capacitance results are compared. A big difference about 45.5 :F in capacitance values for the salt and distilled water shows a high sensitivity, which can be used to recognize different water liquids. The experimental results are promising for water liquids and verify the successful operation of such a device as a liquid sensor, a useful method for checking the electrical quality of the water that is required for different applications.

  7. The role of voltage-gated calcium channels in neurotransmitter phenotype specification: Coexpression and functional analysis in Xenopus laevis

    OpenAIRE

    Lewis, Brittany B.; Miller, Lauren E.; Herbst, Wendy A; Saha, Margaret S.

    2014-01-01

    Calcium activity has been implicated in many neurodevelopmental events, including the specification of neurotransmitter phenotypes. Higher levels of calcium activity lead to an increased number of inhibitory neural phenotypes, whereas lower levels of calcium activity lead to excitatory neural phenotypes. Voltage-gated calcium channels (VGCCs) allow for rapid calcium entry and are expressed during early neural stages, making them likely regulators of activity-dependent neurotransmitter phenoty...

  8. Calcium and bones

    Science.gov (United States)

    Bone strength and calcium ... calcium (as well as phosphorus) to make healthy bones. Bones are the main storage site of calcium in ... your body does not absorb enough calcium, your bones can get weak or will not grow properly. ...

  9. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Some products that contain calcium carbonate are certain: ... and mineral supplements Other products may also contain calcium ...

  10. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... 2 of 4 sections Take Action! Take Action: Calcium Sources Protect your bones – get plenty of calcium ...

  11. Computational study of a calcium release-activated calcium channel

    Science.gov (United States)

    Talukdar, Keka; Shantappa, Anil

    2016-05-01

    The naturally occurring proteins that form hole in membrane are commonly known as ion channels. They play multiple roles in many important biological processes. Deletion or alteration of these channels often leads to serious problems in the physiological processes as it controls the flow of ions through it. The proper maintenance of the flow of ions, in turn, is required for normal health. Here we have investigated the behavior of a calcium release-activated calcium ion channel with pdb entry 4HKR in Drosophila Melanogaster. The equilibrium energy as well as molecular dynamics simulation is performed first. The protein is subjected to molecular dynamics simulation to find their energy minimized value. Simulation of the protein in the environment of water and ions has given us important results too. The solvation energy is also found using Charmm potential.

  12. Complementary surface charge for enhanced capacitive deionization

    NARCIS (Netherlands)

    Gao, X.; Porada, S.; Omosebi, A.; Liu, K.L.; Biesheuvel, P.M.; Landon, J.

    2016-01-01

    Commercially available activated carbon cloth electrodes are treated using nitric acid and ethylenediamine solutions, resulting in chemical surface charge enhanced carbon electrodes for capacitive deionization (CDI) applications. Surface charge enhanced electrodes are then configured in a CDI cel

  13. Oestrous sheep serum balances ROS levels to supply in vitro capacitation of ram spermatozoa.

    Science.gov (United States)

    Del Olmo, E; García-Álvarez, O; Maroto-Morales, A; Ramón, M; Iniesta-Cuerda, M; Martinez-Pastor, F; Montoro, V; Soler, A J; Garde, J J; Fernández-Santos, M R

    2016-10-01

    Reactive oxygen species (ROS) are fundamental for intracellular signalling. In spermatozoa, they are involved both to apoptosis and to capacitation, and changes in ROS levels can alter the balance between these two processes. Oestrous sheep serum (OSS) is considered an efficient agent for in vitro capacitation of ram spermatozoa. We have explored the effects of OSS on ram sperm physiology, especially on ROS production, during in vitro capacitation. Semen samples from 15 rams were cryopreserved. After thawing, samples were submitted to four treatments: control (CTL), 10% OSS supplementation for in vitro sperm capacitation, caspase inhibitor (INH, Z-VAD-FMK 100 μM) and OSS (10%) plus caspase inhibitor (I + E). Sperm samples were incubated for 30 min at 38.5°C and 5% CO2 and evaluated motility and kinetic parameters by computer-assisted semen analysis (CASA) and viability (propidium iodide), apoptotic-like membrane changes (YO-PRO-1), acrosomal status (PNA-FITC), intracellular calcium (FLUO-3), membrane fluidity (M540) and ROS production (CM-H2 DCFDA) by flow cytometry. OSS induced changes in kinetic parameters compatible with capacitation, with a decrease in the percentage of progressive motility and linearity, and an increase in the amplitude of the lateral displacement of the sperm head (p < .05). Moreover, OSS increased the proportion of M540+ viable spermatozoa, YO-PRO-1+ and acrosome-reacted spermatozoa (p < .05). After incubation, OSS and I+E achieved lower ROS levels (p < .05). Ca(2+) levels did not change with the incubation, but were slightly higher (p < .05) when both OSS and the inhibitor were present. We suggest that OSS may modulate ROS levels, allowing intracellular signalling for capacitation to occur while preventing higher levels that could trigger apoptosis.

  14. Oestrous sheep serum balances ROS levels to supply in vitro capacitation of ram spermatozoa.

    Science.gov (United States)

    Del Olmo, E; García-Álvarez, O; Maroto-Morales, A; Ramón, M; Iniesta-Cuerda, M; Martinez-Pastor, F; Montoro, V; Soler, A J; Garde, J J; Fernández-Santos, M R

    2016-10-01

    Reactive oxygen species (ROS) are fundamental for intracellular signalling. In spermatozoa, they are involved both to apoptosis and to capacitation, and changes in ROS levels can alter the balance between these two processes. Oestrous sheep serum (OSS) is considered an efficient agent for in vitro capacitation of ram spermatozoa. We have explored the effects of OSS on ram sperm physiology, especially on ROS production, during in vitro capacitation. Semen samples from 15 rams were cryopreserved. After thawing, samples were submitted to four treatments: control (CTL), 10% OSS supplementation for in vitro sperm capacitation, caspase inhibitor (INH, Z-VAD-FMK 100 μM) and OSS (10%) plus caspase inhibitor (I + E). Sperm samples were incubated for 30 min at 38.5°C and 5% CO2 and evaluated motility and kinetic parameters by computer-assisted semen analysis (CASA) and viability (propidium iodide), apoptotic-like membrane changes (YO-PRO-1), acrosomal status (PNA-FITC), intracellular calcium (FLUO-3), membrane fluidity (M540) and ROS production (CM-H2 DCFDA) by flow cytometry. OSS induced changes in kinetic parameters compatible with capacitation, with a decrease in the percentage of progressive motility and linearity, and an increase in the amplitude of the lateral displacement of the sperm head (p < .05). Moreover, OSS increased the proportion of M540+ viable spermatozoa, YO-PRO-1+ and acrosome-reacted spermatozoa (p < .05). After incubation, OSS and I+E achieved lower ROS levels (p < .05). Ca(2+) levels did not change with the incubation, but were slightly higher (p < .05) when both OSS and the inhibitor were present. We suggest that OSS may modulate ROS levels, allowing intracellular signalling for capacitation to occur while preventing higher levels that could trigger apoptosis. PMID:27491678

  15. Highly sensitive micromachined capacitive pressure sensor with reduced hysteresis and low parasitic capacitance

    DEFF Research Database (Denmark)

    Pedersen, Thomas; Fragiacomo, Giulio; Hansen, Ole;

    2009-01-01

    This paper describes the design and fabrication of a capacitive pressure sensor that has a large capacitance signal and a high sensitivity of 76 pF/bar in touch mode operation. Due to the large signal, problems with parasitic capacitances are avoided and hence it is possible to integrate the sens...... bonding to create vacuum cavities. The exposed part of the sensor is perfectly flat such that it can be coated with corrosion resistant thin films. Hysteresis is an inherent problem in touch mode capacitive pressure sensors and a technique to significantly reduce it is presented....

  16. Automatic Power Factor Correction Using Capacitive Bank

    OpenAIRE

    Mr.Anant Kumar Tiwari,; Mrs. Durga Sharma

    2014-01-01

    The power factor correction of electrical loads is a problem common to all industrial companies. Earlier the power factor correction was done by adjusting the capacitive bank manually [1]. The automated power factor corrector (APFC) using capacitive load bank is helpful in providing the power factor correction. Proposed automated project involves measuring the power factor value from the load using microcontroller. The design of this auto-adjustable power factor correction is ...

  17. Dynamics of Water Entry

    CERN Document Server

    Truscott, Tadd T; Techet, Alexandra H

    2008-01-01

    The hydrodynamics associated with water-entry of spheres can be highly variable with respect to the material and kinematic properties of the sphere. This series of five fluid dynamics videos illustrates several subtle but interesting variations that can be seen. The first series of videos contrasts the nature of impact ($Fr = U_o/\\sqrt{gd} = 5.15$) between a hydrophilic (wetting angle of $\\alpha$ = 60$^\\circ$) and hydrophobic sphere ($\\alpha$ = 120$^\\circ$), and illustrates how surface coating can affect whether or not an air cavity is formed; the views from the side and from above are synchronized in time. The second video series illustrates how spin and surface treatments can alter the splash and cavity formation following water entry. The spinning sphere ($S = \\omega r / U_o = 1.7$; $Fr = 5.15$) causes a wedge of fluid to be drawn into the cavity due to the no-slip condition and follows a curved trajectory. The non-spinning sphere ($Fr = 5.15$) has two distinct surface treatments on the left and right hemi...

  18. Calcium-sensing receptor activation contributed to apoptosis stimulates TRPC6 channel in rat neonatal ventricular myocytes

    International Nuclear Information System (INIS)

    Capacitative calcium entry (CCE) refers to the influx of calcium through plasma membrane channels activated on depletion of endoplasmic sarcoplasmic/reticulum (ER/SR) Ca2+ stores, which is performed mainly by the transient receptor potential (TRP) channels. TRP channels are expressed in cardiomyocytes. Calcium-sensing receptor (CaR) is also expressed in rat cardiac tissue and plays an important role in mediating cardiomyocyte apoptosis. However, there are no data regarding the link between CaR and TRP channels in rat heart. In this study, in rat neonatal myocytes, by Ca2+ imaging, we found that the depletion of ER/SR Ca2+ stores by thapsigargin (TG) elicited a transient rise in cytoplasmic Ca2+ ([Ca2+]i), followed by sustained increase depending on extracellular Ca2+. But, TRP channels inhibitor (SKF96365), not L-type channels or the Na+/Ca2+ exchanger inhibitors, inhibited [Ca2+]i relatively high. Then, we found that the stimulation of CaR with its activator gadolinium chloride (GdCl3) or by an increased extracellular Ca2+([Ca2+]o) increased the concentration of intracelluar Ca2+, whereas, the sustained elevation of [Ca2+]i was reduced in the presence of SKF96365. Similarly, the duration of [Ca2+]i increase was also shortened in the absence of extracellular Ca2+. Western blot analysis showed that GdCl3 increased the expression of TRPC6, which was reversed by SKF96365. Additionally, SKF96365 reduced cardiomyocyte apoptosis induced by GdCl3. Our results suggested that CCE exhibited in rat neonatal myocytes and CaR activation induced Ca2+-permeable cationic channels TRPCs to gate the CCE, for which TRPC6 was one of the most likely candidates. TRPC6 channel was functionally coupled with CaR to enhance the cardiomyocyte apoptosis.

  19. Sport entries and qualification manual

    OpenAIRE

    2014-01-01

    This manual is designed to provide National Olympic Committees (NOCs) with the Olympic Sport Entries process, relevant policies, and instructions for completing the online registration for athletes participating in the Sochi 2014 Olympic Winter Games and to assist NOCs in using the online Sport Entries and Qualification (eSEQ) system to complete the entries of their athletes to the Sochi 2014 Olympic Winter Games.

  20. Capacitance of Graphene Bilayer as a Which-Layer Probe

    OpenAIRE

    Young, Andrea F.; Levitov, Leonid S.

    2011-01-01

    The unique capabilities of capacitance measurements in bilayer graphene enable probing of layer-specific properties that are normally out of reach in transport measurements. Furthermore, capacitance measurements in the top-gate and penetration field geometries are sensitive to different physical quantities: the penetration field capacitance probes the two layers equally, whereas the top gate capacitance preferentially samples the near layer, resulting in the "near-layer capacitance enhancemen...

  1. Nanoscale capacitance: A classical charge-dipole approximation

    OpenAIRE

    Jun-Qiang Lu; Jonathan Gonzalez; Carlos Sierra; Yang Li

    2013-01-01

    Modeling nanoscale capacitance presents particular challenge because of dynamic contribution from electrodes, which can usually be neglected in modeling macroscopic capacitance and nanoscale conductance. We present a model to calculate capacitances of nano-gap configurations and define effective capacitances of nanoscale structures. The model is implemented by using a classical atomic charge-dipole approximation and applied to calculate capacitance of a carbon nanotube nano-gap and effective ...

  2. Intracellular calcium ions as regulators of renal tubular sodium transport.

    Science.gov (United States)

    Windhager, E; Frindt, G; Yang, J M; Lee, C O

    1986-09-15

    This review addresses the putative role of intracellular calcium ions in the regulation of sodium transport by renal tubules. Cytoplasmic calcium-ion activities in proximal tubules of Necturus are less than 10(-7) M and can be increased by lowering the electrochemical potential gradient for sodium ions across the peritubular cell membrane, or by addition of quinidine or ionomycin to peritubular fluid. Whereas lowering of the peritubular Na concentration increases cytosolic [Ca++] and [H+], ionomycin, a calcium ionophore, raises intracellular [Ca++] without decreasing pHi. The intracellular calcium-ion level is maintained by transport processes in the plasma membrane and membranes of intracellular organelles, as well as by calcium-binding proteins. Calcium ions inhibit net transport of sodium by reducing the rate of sodium entry across the luminal cell membrane. In the collecting tubule this inhibition is caused, at least in part, by an indirect reduction in the activity of the amiloride-sensitive sodium channel. PMID:2430134

  3. Entry deterrence and experimentation under demand uncertainty

    OpenAIRE

    Jain, N

    2011-01-01

    We examine the effect of a threat of entry on experimentation about demand by an incumbent monopolist when there is a fixed cost of entry. We show that experimentation may itself be used as a tool for entry deterrence and derive conditions under which experimentation reduces the probability of entry. These conditions depend on the entry rule which in turn depends on entry costs. We show that if experimentation does not deter entry, the monopolist incumbent experiments less. We also characteri...

  4. Carbon flow electrodes for continuous operation of capacitive deionization and capacitive mixing energy generation

    NARCIS (Netherlands)

    Porada, S.; Hamelers, H.V.M.; Bryjak, M.; Presser, V.; Biesheuvel, P.M.; Weingarth, D.

    2014-01-01

    Capacitive technologies, such as capacitive deionization and energy harvesting based on mixing energy (“capmix” and “CO2 energy”), are characterized by intermittent operation: phases of ion electrosorption from the water are followed by system regeneration. From a system application point of view, c

  5. Calcium source (image)

    Science.gov (United States)

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  6. Calcium hydroxide poisoning

    Science.gov (United States)

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  7. Calcium and bones (image)

    Science.gov (United States)

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  8. Coronary Calcium Scan

    Science.gov (United States)

    ... the NHLBI on Twitter. What Is a Coronary Calcium Scan? A coronary calcium scan is a test ... you have calcifications in your coronary arteries. Coronary Calcium Scan Figure A shows the position of the ...

  9. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  10. Ion channels, phosphorylation and mammalian sperm capacitation.

    Science.gov (United States)

    Visconti, Pablo E; Krapf, Dario; de la Vega-Beltrán, José Luis; Acevedo, Juan José; Darszon, Alberto

    2011-05-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies.

  11. Ion channels, phosphorylation and mammalian sperm capacitation

    Institute of Scientific and Technical Information of China (English)

    Pablo E Visconti; Dario Krapf; José Luis de la Vega-Beltrán; Juan José Acevedo; Alberto Darszon

    2011-01-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies.

  12. Carbon nanofiber supercapacitors with large areal capacitances

    KAUST Repository

    McDonough, James R.

    2009-01-01

    We develop supercapacitor (SC) devices with large per-area capacitances by utilizing three-dimensional (3D) porous substrates. Carbon nanofibers (CNFs) functioning as active SC electrodes are grown on 3D nickel foam. The 3D porous substrates facilitate a mass loading of active electrodes and per-area capacitance as large as 60 mg/ cm2 and 1.2 F/ cm2, respectively. We optimize SC performance by developing an annealing-free CNF growth process that minimizes undesirable nickel carbide formation. Superior per-area capacitances described here suggest that 3D porous substrates are useful in various energy storage devices in which per-area performance is critical. © 2009 American Institute of Physics.

  13. A high performance, variable capacitance accelerometer

    Science.gov (United States)

    Wilner, L. Bruce

    1988-12-01

    A variable capacitance acceleration sensor is described. Manufactured using silicon microfabrication techniques, the sensor uses a midplane, flat plate suspension, gas damping, and overrange stops. The sensor is assembled from three silicon wafers, using anodic bonds to inlays of borosilicate glass. Typical sensor properties are 7-pF active capacitance, 3-pF tare capacitance, a response of 0.05 pF/G, a resonance frequency of 3.4 kHz, and damping 0.7 critical. It is concluded that this sensor, with appropriate electronics, forms an accelerometer with an order-of-magnitude greater sensitivity-bandwidth product than a comparable piezoresistive acclerometer, and with extraordinary shock resistance.

  14. Microphonics in biopotential measurements with capacitive electrodes.

    Science.gov (United States)

    Luna-Lozano, Pablo S; Pallas-Areny, Ramon

    2010-01-01

    Biopotential measurements with capacitive electrodes do not need any direct contact between electrode and skin, which saves the time devoted to expose and prepare the contact area when measuring with conductive electrodes. However, mechanical vibrations resulting from physiological functions such as respiration and cardiac contraction can change the capacitance of the electrode and affect the recordings. This transformation of mechanical vibrations into undesired electric signals is termed microphonics. We have evaluated microphonics in capacitive ECG recordings obtained from a dressed subject seated on a common chair with electrodes placed on the front side of the backrest of the chair. Depending on the softness of the backrest, the recordings may be clearly affected by the displacement of the thorax back wall due to the respiration and to the heart's mechanical activity.

  15. Glial calcium signaling in physiology and pathophysioilogy

    Institute of Scientific and Technical Information of China (English)

    Alexei VERKHRASKY

    2006-01-01

    Neuronal-glial circuits underlie integrative processes in the nervous system.Function of glial syncytium is,to a very large extent,regulated by the intracellular calcium signaling system.Glial calcium signals are triggered by activation of multiple receptors,expressed in glial membrane,which regulate both Ca2+ entry and Ca2+ release from the endoplasmic reticulum.The endoplasmic reticulum also endows glial cells with intracellular excitable media,which is able to produce and maintain long-ranging signaling in a form of propagating Ca2+ waves.In pathological conditions,calcium signals regulate glial response to injury,which might have both protective and detrimental effects on the nervous tissue.

  16. The pyramidal capacitated vehicle routing problem

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    2010-01-01

    This paper introduces the pyramidal capacitated vehicle routing problem (PCVRP) as a restricted version of the capacitated vehicle routing problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the pyramidal traveling salesman problem (PTSP). A pyramidal....... A main feature of the algorithm is that exact pricing over elementary routes are done in pseudo-polynomial time. Computational results suggest that PCVRP solutions are highly useful for obtaining near-optimal solutions to the CVRP. Furthermore, pricing of pyramidal routes may prove to be very useful...

  17. Experimental study of negative capacitance in LEDs

    Institute of Scientific and Technical Information of China (English)

    FENG Lie-feng; WANG Jun; ZHU Chuan-yun; CONG Hong-xia; CHEN Yong; WANG Cun-da

    2005-01-01

    The experimental study on negative capacitance(NC) of various light-emitting diodes(LEDs) is presented.Experimental result shows that all LEDs display the NC phenomenon.The voltage modulated electroluminescence(VMEL) experiment confirms that the reason of negative capacitance is the strong recombination of the injected carriers in the active region of luminescence.The measures also verify that the dependence of NC on voltage and frequency in different LEDs is similar: NC phenomenon is more obvious with higher voltage or lower frequency.

  18. Design and simulation of MEMS capacitive magnetometer

    Science.gov (United States)

    Jyoti, Aditi, Tripathi, C. C.; Gopal, Ram

    2016-04-01

    This paper presents the design and simulation of a MEMS Capacitive Magnetometer using FEM (Finite Element Method) tool COMSOL Multiphysics 4.3b and results from this simulation are closely matched with analytically calculated results. A comb drive structure is used for actuation purpose which operates at resonant frequency of device is 11.791 kHz to achieve maximum displacement. A magnetic field in z-axis can be detected by this comb drive structure. Quality factor of MEMS capacitive magnetometer obtained is 18 and it has good linear response in the magnetic field range of 100 µT.

  19. Expression, cellular localization, and involvement of the pentose phosphate pathway enzymes in the regulation of ram sperm capacitation.

    Science.gov (United States)

    Luna, C; Serrano, E; Domingo, J; Casao, A; Pérez-Pé, R; Cebrián-Pérez, J A; Muiño-Blanco, T

    2016-08-01

    Spermatozoa require substantially more ATP than other cells, not only for sustaining sperm motility but also for regulating protein phosphorylation during capacitation. In this study, we have reported for the first time the presence of the two key enzymes of the pentose phosphate pathway (PPP), glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in ovine spermatozoa by indirect immunofluorescence, Western blotting, in-gel activity, and reverse transcription polymerase chain reaction analysis. We found that the activity of both enzymes significantly increased after in vitro capacitation in the presence of high-cAMP levels, with a concomitant increase in protein tyrosine phosphorylation and in the proportion of sperm-capacitated pattern assessed by the chlortetracycline staining. These results suggest that PPP is related with the progress of capacitation and that a relationship between calcium compartmentalization, protein tyrosine phosphorylation and PPP seems to exist. This is the first report that shows a connection between the PPP, cAMP/PKA signaling pathways and sperm capacitation. These findings can be of high-biological importance to improve our knowledge of the biochemical mechanisms involved in the acquisition of mammalian sperm functional competence and, ultimately, fertility.

  20. Development of a 3D capacitive gyroscope with reduced parasitic capacitance

    International Nuclear Information System (INIS)

    We present the development of a technological platform dedicated to 3D capacitive inertial sensors. The proof of concept will be made on a 3D gyroscope. The mobile structure is made within a 30 µm thick Si top layer of a SOI substrate, while poly-Si deposited on top of a sacrificial PSG layer serves as suspended top electrodes and connection wires. This technology enables us to maintain low parasitic capacitance, which is of paramount significance for capacitive detection. After packaging and association with an analogue electronic board, functionality of the sensor is demonstrated. (paper)

  1. Brownfield Entry in Emerging Markets

    OpenAIRE

    Meyer, Klaus E.; Saul Estrin

    2001-01-01

    This paper focuses on the brown-field entry mode, as a special case of acquisition, in which the resources transferred by the investor dominate over those provided by the acquired firm. We see this mode as having particular relevance for entry strategies in emerging markets. The choice of entry mode is analyzed on the basis of a framework utilizing both resource-based and transaction-cost theories. The resource requirements have to be matched with resources available to the investor through a...

  2. Financial Intermediation and Entry Deterrence

    OpenAIRE

    Jain, Neelam; Thomas D. Jeitschko; Mirman, Leonard J.

    2001-01-01

    In this paper, we analyze the interaction between an incumbent firm's financial contract with abank and its product market decisions in the face of the threat of entry, in a dynamic model.The main results of the paper are: there exists a separating equilibrium with no limit pricing; thelow-cost incumbent repays more to the bank in the first period, due to the threat of entry; andthere are parameter values for which the bank makes more profits with the threat of entry thanwithout.

  3. Calcium and Vitamin D

    Science.gov (United States)

    ... Home › Patients › Treatment › Calcium/Vitamin D Calcium/Vitamin D Getting enough calcium and vitamin D is essential ... counter medications and calcium supplements. What is Vitamin D and What Does it Do? Vitamin D plays ...

  4. Entry Threat and Entry Deterrence: The Timing of Broadband Rollout

    OpenAIRE

    Mo Xiao; Orazem, Peter F.

    2007-01-01

    Past empirical literature provides strong evidence that competition increases when new firms enter a market. However, rarely have economists been able to examine how competition changes with the threat of entry. This paper uses the evolution of the zip code level market structure of facilities-based broadband providers from 1999 to 2004 to investigate how a firm adjusts its entry strategy when facing the threat of additional entrants. We identify the potential entrant into a local market as t...

  5. Quantum capacitance of the armchair-edge graphene nanoribbon

    Indian Academy of Sciences (India)

    Ling-Feng Mao

    2013-08-01

    The quantum capacitance, an important parameter in the design of nanoscale devices, is derived for armchair-edge single-layer graphene nanoribbon with semiconducting property. The quantum capacitance oscillations are found and these capacitance oscillations originate from the lateral quantum confinement in graphene nanoribbon. Detailed studies of the capacitance oscillations demonstrate that the local channel electrostatic potential at the capacitance peak, the height and the number of the capacitance peak strongly depend on the width, especially a few nanometres, of the armchair-edge graphene nanoribbon. It implies that the capacitance oscillations observed in the experiments can be utilized to measure the width of graphene nanoribbon. The results also show that the capacitance oscillations are not seen when the width is larger than 30 nm.

  6. Analysis of mutual capacitance and inductance of printed circuit

    OpenAIRE

    Ivanov, V. G.

    2014-01-01

    The article analyzes the mutual capacitance and inductance of printed circuit and introduces an evaluation technique for conductor-to-conductor capacitance under electrical connections tracing, the technique based on a multi-layer channel model.

  7. Observation of Quantum Capacitance of individual single walled carbon nanotubes

    OpenAIRE

    Dai, Junfeng; Li, Jun; Zeng, Hualing; Cui, Xiaodong

    2008-01-01

    We report a measurement on quantum capacitance of individual semiconducting and small band gap SWNTs. The observed quantum capacitance is remarkably smaller than that originating from density of states and it implies a strong electron correlation in SWNTs.

  8. An in vitro investigation of the anodic polarization and capacitance behavior of 316-L stainless steel.

    Science.gov (United States)

    Sutow, E J; Pollack, S R; Korostoff, E

    1976-09-01

    Determinations were made of how the corrosion-resistant properties of the passive film on 316-L stainless steel are influenced by the material's mechanical and surface states, and the variable pH and PO2 conditions of the interstitial fluid. Cold-rolled and annealed specimens were surface-prepared, commercially and in the laboratory, respectively, as if for orthopedic implantation. Passive film behavior was studied by the anodic polarization and pulse-potentiostatic capacitance methods. The pH and PO2 of the Ringer's test solution were varied to include interstitial fluid values occurring postoperatively and onto recovery. The anodic polarization behavior of all specimens was found to be pH- and PO2-independent. Breakdown potentials of annealed specimens were 800-950 mV (SCE), in contrast to previously reported values of approximately 350 mV. This substantial increase is related to the influence of surface preparation and, in particular, to the optimization of electropolishing time which acts to produce a microscopically smooth surface, free of debris and disarrayed material. Capacitance behavior of annealed material for potentials greater than 400 mV was consistent with a model involving the entry of chloride and metal ions (mostly Fe) into the passive film. This entry is related to the onset of pitting. PMID:10307

  9. Thermodynamic cycle analysis for capacitive deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.

    2009-01-01

    Capacitive deionization (CDI) is an ion removal technology based on temporarily storing ions in the polarization layers of two oppositely positioned electrodes. Here we present a thermodynamic model for the minimum work required for ion separation in the fully reversible case by describing the ionic

  10. Capacitive Proximity Sensors With Additional Driven Shields

    Science.gov (United States)

    Mcconnell, Robert L.

    1993-01-01

    Improved capacitive proximity sensors constructed by incorporating one or more additional driven shield(s). Sensitivity and range of sensor altered by adjusting driving signal(s) applied to shield(s). Includes sensing electrode and driven isolating shield that correspond to sensing electrode and driven shield.

  11. Phase-Discriminating Capacitive Sensor System

    Science.gov (United States)

    Vranish, John M.; Rahim, Wadi

    1993-01-01

    Crosstalk eliminated by maintaining voltages on all electrodes at same amplitude, phase, and frequency. Each output feedback-derived control voltage, change of which indicates proximity-induced change in capacitance of associated sensing electrode. Sensors placed close together, enabling imaging of sort. Images and/or output voltages used to guide robots in proximity to various objects.

  12. Capacitive Displacement Sensor With Frequency Readout

    Science.gov (United States)

    Fritsch, Klaus

    1989-01-01

    Simple displacement-measuring circuit senses capacitance between two parallel conducting plates and produces output signal, with frequency proportional to distance between plates. Principle of circuit provides advantages over other methods because of frequency-encoded output and high linearity. Used to measure displacements.

  13. Site Specific Evaluation of Multisensor Capacitance Probes

    Science.gov (United States)

    Multisensor capacitance probes (MCPs) are widely used for measuring soil water content (SWC) at the field scale. Although manufacturers supply a generic MCP calibration, many researchers recognize that MCPs should be calibrated for specific field conditions. MCPs measurements are typically associa...

  14. Capacitors and Resistance-Capacitance Networks.

    Science.gov (United States)

    Balabanian, Norman; Root, Augustin A.

    This programed textbook was developed under a contract with the United States Office of Education as Number 5 in a series of materials for use in an electrical engineering sequence. It is divided into three parts--(1) capacitors, (2) voltage-current relationships, and (3) simple resistance-capacitance networks. (DH)

  15. Negative capacitance in multidomain ferroelectric superlattices

    Science.gov (United States)

    Zubko, Pavlo; Wojdeł, Jacek C.; Hadjimichael, Marios; Fernandez-Pena, Stéphanie; Sené, Anaïs; Luk’Yanchuk, Igor; Triscone, Jean-Marc; Íñiguez, Jorge

    2016-06-01

    The stability of spontaneous electrical polarization in ferroelectrics is fundamental to many of their current applications, which range from the simple electric cigarette lighter to non-volatile random access memories. Research on nanoscale ferroelectrics reveals that their behaviour is profoundly different from that in bulk ferroelectrics, which could lead to new phenomena with potential for future devices. As ferroelectrics become thinner, maintaining a stable polarization becomes increasingly challenging. On the other hand, intentionally destabilizing this polarization can cause the effective electric permittivity of a ferroelectric to become negative, enabling it to behave as a negative capacitance when integrated in a heterostructure. Negative capacitance has been proposed as a way of overcoming fundamental limitations on the power consumption of field-effect transistors. However, experimental demonstrations of this phenomenon remain contentious. The prevalent interpretations based on homogeneous polarization models are difficult to reconcile with the expected strong tendency for domain formation, but the effect of domains on negative capacitance has received little attention. Here we report negative capacitance in a model system of multidomain ferroelectric–dielectric superlattices across a wide range of temperatures, in both the ferroelectric and paraelectric phases. Using a phenomenological model, we show that domain-wall motion not only gives rise to negative permittivity, but can also enhance, rather than limit, its temperature range. Our first-principles-based atomistic simulations provide detailed microscopic insight into the origin of this phenomenon, identifying the dominant contribution of near-interface layers and paving the way for its future exploitation.

  16. Inside-out electrical capacitance tomography

    DEFF Research Database (Denmark)

    Kjærsgaard-Rasmussen, Jimmy; Meyer, Knud Erik

    2011-01-01

    In this work we demonstrate the construction of an ‘inside-out’ sensor geometry for electrical capacitance tomography (ECT). The inside-out geometry has the electrodes placed around a tube, as usual, but measuring ‘outwards’. The flow between the electrodes and an outer tube is reconstructed...

  17. Tactile Data Entry System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Building on our successful Phase I Tactile Data Entry program, Barron Associates proposes development of a Glove-Enabled Computer Operations (GECO) system to permit...

  18. Entry, Descent, Landing Animation (Animation)

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for Entry, Descent, Landing animation This animation illustrates the path the Stardust return capsule will follow once it enters Earth's atmosphere.

  19. Assessment of cardiac function in mice lacking the mitochondrial calcium uniporter.

    Science.gov (United States)

    Holmström, Kira M; Pan, Xin; Liu, Julia C; Menazza, Sara; Liu, Jie; Nguyen, Tiffany T; Pan, Haihui; Parks, Randi J; Anderson, Stasia; Noguchi, Audrey; Springer, Danielle; Murphy, Elizabeth; Finkel, Toren

    2015-08-01

    Mitochondrial calcium is thought to play an important role in the regulation of cardiac bioenergetics and function. The entry of calcium into the mitochondrial matrix requires that the divalent cation pass through the inner mitochondrial membrane via a specialized pore known as the mitochondrial calcium uniporter (MCU). Here, we use mice deficient of MCU expression to rigorously assess the role of mitochondrial calcium in cardiac function. Mitochondria isolated from MCU(-/-) mice have reduced matrix calcium levels, impaired calcium uptake and a defect in calcium-stimulated respiration. Nonetheless, we find that the absence of MCU expression does not affect basal cardiac function at either 12 or 20months of age. Moreover, the physiological response of MCU(-/-) mice to isoproterenol challenge or transverse aortic constriction appears similar to control mice. Thus, while mitochondria derived from MCU(-/-) mice have markedly impaired mitochondrial calcium handling, the hearts of these animals surprisingly appear to function relatively normally under basal conditions and during stress.

  20. Anisotropic magneto-capacitance in ferromagnetic-plate capacitors

    OpenAIRE

    Haigh, J. A.; Ciccarelli, C; Betz, A. C.; Irvine, A; Novák, V.; Jungwirth, T.; Wunderlich, J.

    2015-01-01

    The capacitance of a parallel plate capacitor can depend on applied magnetic field. Previous studies have identified capacitance changes induced via classical Lorentz force or spin-dependent Zeeman effects. Here we measure a magnetization direction dependent capacitance in parallel-plate capacitors where one plate is a ferromagnetic semiconductor, gallium manganese arsenide. This anisotropic magneto-capacitance is due to the anisotropy in the density of states dependent on the magnetization t...

  1. Membrane capacitance techniques to monitor granule exocytosis in neutrophils.

    OpenAIRE

    Lollike, K; Lindau, M

    1999-01-01

    Cell membranes behave like electrical capacitors and changes in cell capacitance therefore reflect changes in the cell area. Monitoring capacitance can thus be used to study dynamic cellular phenomenon involving rapid changes in cell surface, such as exo- and/or endocytosis. In this review focus is on the use of capacitance techniques to study exocytosis in human neutrophils. We compare the whole-cell and the cell-attached capacitance techniques, and we review the complete literature dealing ...

  2. Negative Quantum Capacitance of Carbon Nanotube Field-Effect Transistors

    OpenAIRE

    Latessa, L.; Pecchia, A.; Di Carlo, A.; P. Lugli

    2004-01-01

    Atomistic density functional theory (DFT) calculations of the capacitance between a metallic cylindric gate and a carbon nanotube (CNT) are reported. Results stressing the predominant effect of quantum capacitance in limiting or even enhancing screening properties of the CNT are shown. Other contributions to the quantum capacitance beyond the electronic density of state (DOS) are pointed out. Negative values of the quantum capacitance are obtained for low-density systems, which correspondingl...

  3. MOS Capacitance-Voltage Characteristics:V.Methods to Enhance the Trapping Capacitance

    Institute of Scientific and Technical Information of China (English)

    揭斌斌; 薩支唐

    2012-01-01

    Low-frequency and High-frequency Capacitance-Voltage (C-V) curves of Silicon Metal-Oxide-Semiconductor Capacitors,showing electron and hole trapping at shallow-level dopant and deep-level generationrecombination-trapping impurities,are presented to illustrate the enhancement of the giant trapping capacitances by physical means via device and circuit designs,in contrast to chemical means via impurity characteristics previously reported.Enhancement is realized by masking the electron or/and hole storage capacitances to make the trapping capacitances dominant at the terminals.Device and materials properties used in the computed CV curves are selected to illustrate experimental realizations for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.

  4. Network Competition and Entry Deterrence

    OpenAIRE

    Calzada, Joan; Valletti, Tommaso

    2005-01-01

    We develop a model of logit demand that extends to a multi-firm industry the traditional duopoly framework of network competition with access charges. Firstly, we show that, when incumbents do not face the threat of entry and compete in prices, they inefficiently establish the reciprocal access charge below cost. This inefficiency disappears if incumbents compete in utilities instead of prices. Secondly, we study how incumbents change their choices under the threat of entry when they determin...

  5. Winding Capacitance Dividing Method for Powerformer

    Institute of Scientific and Technical Information of China (English)

    TIAN Qing; LIN Xiang-ning; LI Jian-jian; TAO Yong-hong

    2008-01-01

    It presents a method which can equivalently arrange the capacitance distribution along with the winding ofthe generator on the terminal and neutral respectively in a reasonable partition, particularly for a type of high-voltagegraded insulated cable wound generator, Powerformer. The winding of the Powerformer adopts graded insulation,which leads to the various cable thicknesses in different portion of the winding, and thus, the uneven capacitancedistribution. The large capacitive currents and large transient outrush currents resulting from the cable consisting ofthe stator winding of Powerformer may cause problems to the generator differential protection. Most of literatures a-vailable in the field of compensated differential protection focus on the charging current compensation for long trans-mission line, instead of for generator. The authors give a method which can be used to compensate the capacitivecurrent wholly to improve the reliability of the differential protection of Powerformer. It is proved that the distribu-ted capacitance can be equivalent as the lump circuit with a capacitance partition coefficient p, and p is proved as aconstant no matter whether the generator experiences the normal operation, external phase(s) fault or internal phase(s) fault. The formula of the partition coefficient is provided and the corresponding equivalent circuit of the Power-former cable to calculate capacitance currents is given. An analysis programming resolving the minimum value of thecoefficient p is written in MATLAB 7. 0/m according to this formula, using the function fmincon() which can workin any type of constraint condition. The program always gets the same global minimum points under the different in-itial values condition which proves our point by mathematical test. With this new approach to winding capacitancedividing method, the protection scheme used for Powerformer can be validated and improved accordingly.

  6. Electric field theory and the fallacy of void capacitance

    OpenAIRE

    McAllister, Iain Wilson

    1991-01-01

    The concept of the capacitance of a gaseous void is discussed as applied to electrical insulation science. The most pertinent aspect of the capacitance definition is that of reference to a single-valued potential difference between surfaces. This implies that these surfaces must be surfaces of equipotential. With this essential characteristics the validity of void capacitance is examined

  7. 19 CFR 191.143 - Drawback entry.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) DRAWBACK Foreign-Built Jet Aircraft Engines Processed in the United States § 191.143 Drawback entry. (a) Filing of entry. Drawback entries covering these foreign-built jet aircraft engines shall be filed on Customs Form 7551, modified to show that the entry covers jet aircraft engines processed...

  8. 19 CFR 142.16 - Entry summary documentation.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Entry summary documentation. 142.16 Section 142.16... TREASURY (CONTINUED) ENTRY PROCESS Entry Summary Documentation § 142.16 Entry summary documentation. (a) Entry summary not filed at time of entry. When the entry documentation is filed before the entry...

  9. Calcium signaling and T-type calcium channels in cancer cell cycling

    Institute of Scientific and Technical Information of China (English)

    James T Taylor; Xiang-Bin Zeng; Jonathan E Pottle; Kevin Lee; Alun R Wang; Stephenie G Yi; Jennifer A S Scruggs; Suresh S Sikka; Ming Li

    2008-01-01

    Regulation of intracellular calcium is an important signaling mechanism for cell proliferation in both normal and cancerous cells. In normal epithelial cells,free calcium concentration is essential for cells to enter and accomplish the S phase and the M phase of the cell cycle. In contrast, cancerous cells can pass these phases of the cell cycle with much lower cytoplasmic free calcium concentrations, indicating an alternative mechanism has developed for fulfilling the intracellular calcium requirement for an increased rate of DNA synthesis and mitosis of fast replicating cancerous cells. The detailed mechanism underlying the altered calcium loading pathway remains unclear;however, there is a growing body of evidence that suggests the T-type Ca2+ channel is abnormally expressed in cancerous cells and that blockade of these channels may reduce cell proliferation in addition to inducing apoptosis. Recent studies also show that the expression of T-type Ca2+ channels in breast cancer cells is proliferation state dependent, i.e. the channels are expressed at higher levels during the fast-replication period, and once the cells are in a non-proliferation state, expression of this channel isminimal. Therefore, selectively blocking calcium entry into cancerous cells may be a valuable approach for preventing tumor growth. Since T-type Ca2+ channels are not expressed in epithelial cells, selective T-type Ca2+ channel blockers may be useful in the treatment of certain types of cancers.

  10. Reconstruction of the Genesis Entry

    Science.gov (United States)

    Desai, Prasun N.; Qualls, Garry D.; Schoenenberger, Mark

    2007-01-01

    An overview of the reconstruction analyses performed for the Genesis capsule entry is described. The results indicate that the actual entry prior to the drogue deployment failure was very close to the pre-entry predictions. The capsule landed 8.3 km south of the desired target at Utah Test and Training Range. Analysis on infrared video footage (obtained from the tracking stations) during the descent estimated the onset of the capsule tumble at Mach 0.9. Frequency analysis on the infrared video data indicates that the aerodynamics generated for the Genesis capsule reasonably predicted the drag and static stability. Observations of the heatshield support the pre-entry simulation estimates of a small hypersonic angles-of-attack, since there is very little, if any, charring of the shoulder region or the aftbody. Through this investigation, an overall assertion can be made that all the data gathered from the Genesis entry is consistent with flight performance that was close to the nominal preentry prediction. Consequently, the design principles and methodologies utilized for the flight dynamics, aerodynamics, and aerothermodynamics analyses have been corroborated.

  11. Porous Alumina Based Capacitive MEMS RH Sensor

    CERN Document Server

    Juhasz, L; Timar-Horvath, Veronika; Desmulliez, Marc; Dhariwal, Resh

    2008-01-01

    The aim of a joint research and development project at the BME and HWU is to produce a cheap, reliable, low-power and CMOS-MEMS process compatible capacitive type relative humidity (RH) sensor that can be incorporated into a state-of-the-art, wireless sensor network. In this paper we discuss the preparation of our new capacitive structure based on post-CMOS MEMS processes and the methods which were used to characterize the thin film porous alumina sensing layer. The average sensitivity is approx. 15 pF/RH% which is more than a magnitude higher than the values found in the literature. The sensor is equipped with integrated resistive heating, which can be used for maintenance to reduce drift, or for keeping the sensing layer at elevated temperature, as an alternative method for temperature-dependence cancellation.

  12. The Pyramidal Capacitated Vehicle Routing Problem

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    This paper introduces the Pyramidal Capacitated Vehicle Routing Problem (PCVRP) as a restricted version of the Capacitated Vehicle Routing Problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the Pyramidal Traveling Salesman Problem (PTSP). A pyramidal...... of a pyramidal route is such that its traversal can be divided in two parts, where on the first part of the route, customers are visited in nondecreasing distance from the depot, and on the remaining part of the route, customers are visited in nonincreasing distance from the depot. Such a route shape is indeed...... found in many optimal solutions to CVRP instances. An optimal solution to the PCVRP may therefore be useful in itself as a heuristic solution to the CVRP. Further, an attempt can be made to find an even better CVRP solution by solving a TSP, possibly leading to a non-pyramidal route, for each...

  13. Automatic Power Factor Correction Using Capacitive Bank

    Directory of Open Access Journals (Sweden)

    Mr.Anant Kumar Tiwari,

    2014-02-01

    Full Text Available The power factor correction of electrical loads is a problem common to all industrial companies. Earlier the power factor correction was done by adjusting the capacitive bank manually [1]. The automated power factor corrector (APFC using capacitive load bank is helpful in providing the power factor correction. Proposed automated project involves measuring the power factor value from the load using microcontroller. The design of this auto-adjustable power factor correction is to ensure the entire power system always preserving unity power factor. The software and hardware required to implement the suggested automatic power factor correction scheme are explained and its operation is described. APFC thus helps us to decrease the time taken to correct the power factor which helps to increase the efficiency.

  14. Layer resolved capacitive probing of graphene bilayers

    Science.gov (United States)

    Zibrov, Alexander; Parmentier, François; Li, Jia; Wang, Lei; Hunt, Benjamin; Dean, Cory; Hone, James; Taniguchi, Takashi; Watanabe, Kenji; Young, Andrea

    Compared to single layer graphene, graphene bilayers have an additional ``which-layer'' degree of freedom that can be controlled by an external electric field in a dual-gated device geometry. We describe capacitance measurements capable of directly probing this degree of freedom. By performing top gate, bottom gate, and penetration field capacitance measurements, we directly extract layer polarization of both Bernal and twisted bilayers. We will present measurements of hBN encapsulated bilayers at both zero and high magnetic field, focusing on the physics of the highly degenerate zero-energy Landau level in the high magnetic field limit where spin, valley, and layer degeneracy are all lifted by electronic interactions.

  15. CMOS Integrated Capacitive DC-DC Converters

    CERN Document Server

    Van Breussegem, Tom

    2013-01-01

    This book provides a detailed analysis of all aspects of capacitive DC-DC converter design: topology selection, control loop design and noise mitigation. Readers will benefit from the authors’ systematic overview that starts from the ground up, in-depth circuit analysis and a thorough review of recently proposed techniques and design methodologies.  Not only design techniques are discussed, but also implementation in CMOS is shown, by pinpointing the technological opportunities of CMOS and demonstrating the implementation based on four state-of-the-art prototypes.  Provides a detailed analysis of all aspects of capacitive DC-DC converter design;  Analyzes the potential of this type of DC-DC converter and introduces a number of techniques to unleash their full potential; Combines system theory with practical implementation techniques; Includes unique analysis of CMOS technology for this application; Provides in-depth analysis of four fabricated prototypes.

  16. Performance relations in Capacitive Deionization systems

    OpenAIRE

    Limpt, van, C.

    2010-01-01

    Capacitive Deionization (CDI) is a relatively new deionization technology based on the temporary storage of ions on an electrically charged surface. By directing a flow between two oppositely charged surfaces, negatively charged ions will adsorb onto the positively charged surface, and positively charged ions will adsorb onto the negatively charged surface. To optimize CDI design for various applications, performance relations in CDI systems have to be understood. CDI performance is determine...

  17. THERMAL DRIFT CHARACTERISTICS OF CAPACITIVE PRESSURE SENSORS

    OpenAIRE

    ABDELAZIZ BEDDIAF; FOUAD KERROUR; SALAH KEMOUCHE

    2016-01-01

    The capacitive pressure sensors based on silicon are characterized by their very high sensitivities and their low power consumption. Nevertheless, their thermal behavior remains more or less unpredictable because they can indicate very high thermal coefficients. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristics drift. In this study, we modeled the thermal behavior of this sensors, using Finite Element Analysis (FE...

  18. Ultra-High-Frequency Capacitive Displacement Sensor

    Science.gov (United States)

    Vanzandt, Thomas R.; Kenny, Thomas W.; Kaiser, William J.

    1994-01-01

    Improved class of compact, high-resolution capacitive displacement sensors operates at excitation frequency of 915 MHz and measures about 7.5 by 4 by 2 centimeters. Contains commercially available 915-MHz oscillator and transmission-line resonator. Resonator contains stripline inductor in addition to variable capacitor. Ultrahigh excitation frequency offers advantages of resolution and frequency response. Not deleteriously affected by mechanical overdriving, or contact between electrodes.

  19. Capacitive Sensors And Targets Would Measure Alignments

    Science.gov (United States)

    Jenstrom, Del T.

    1994-01-01

    Multiple capacitive sensors and active targets used to measure distance between, and relative orientation of, two objects. Sensed target signals processed and used by control systems to align objects to be joined. Shapes, sizes, and layouts of sensors and targets optimized for specific application. Particular layout of targets and sensors enables determination of relative position and orientation of two objects in all six degrees of freedom.

  20. Development of a capacitive bioimpedance measurement system

    OpenAIRE

    Gómez Abad, Daniel

    2009-01-01

    Bioelectrical impedance spectroscopy (BIS) is a well-established and non-invasive method to determine and monitor body composition. Commercially available bioelectrical impedance systems use coated hydrogel-aluminium electrodes, where the hydrogel acts as an adhesive and as an electrolytic medium. The gel/adhesive is physiologically inert over short periods. However, when used over longer periods, hydrogel-aluminium electrodes present limitations, which capacitive electrodes ma...

  1. The fringe capacitance formula of microstructures

    International Nuclear Information System (INIS)

    This paper presents a fringe capacitance formula of microstructures. The formula is derived by curve fitting on ANSYS simulation results. Compared with the ANSYS and experimental results, the deviation is within ±2%. The application to determine the pull-in voltage of an electrostatic micro-beam is demonstrated, which agrees very well with the experimental data. The formula presented is very accurate, yields explicit physical meanings and is applicable to common dimension ranges for MEMS devices. (paper)

  2. Calcium channel blocker overdose

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002580.htm Calcium channel blocker overdose To use the sharing features on this page, please enable JavaScript. Calcium channel blockers are a type of medicine used ...

  3. Fenoprofen calcium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002649.htm Fenoprofen calcium overdose To use the sharing features on this page, please enable JavaScript. Fenoprofen calcium is a type of medicine called a nonsteroidal ...

  4. Calcium signaling mediates cold sensing in insect tissues.

    Science.gov (United States)

    Teets, Nicholas M; Yi, Shu-Xia; Lee, Richard E; Denlinger, David L

    2013-05-28

    The ability to rapidly respond to changes in temperature is a critical adaptation for insects and other ectotherms living in thermally variable environments. In a process called rapid cold hardening (RCH), insects significantly enhance cold tolerance following brief (i.e., minutes to hours) exposure to nonlethal chilling. Although the ecological relevance of RCH is well-established, the underlying physiological mechanisms that trigger RCH are poorly understood. RCH can be elicited in isolated tissues ex vivo, suggesting cold-sensing and downstream hardening pathways are governed by brain-independent signaling mechanisms. We previously provided preliminary evidence that calcium is involved in RCH, and here we firmly establish that calcium signaling mediates cold sensing in insect tissues. In tracheal cells of the freeze-tolerant goldenrod gall fly, Eurosta solidaginis, chilling to 0 °C evoked a 40% increase in intracellular calcium concentration as determined by live-cell confocal imaging. Downstream of calcium entry, RCH conditions significantly increased the activity of calcium/calmodulin-dependent protein kinase II (CaMKII) while reducing phosphorylation of the inhibitory Thr306 residue. Pharmacological inhibitors of calcium entry, calmodulin activation, and CaMKII activity all prevented ex vivo RCH in midgut and salivary gland tissues, indicating that calcium signaling is required for RCH to occur. Similar results were obtained for a freeze-intolerant species, adults of the flesh fly, Sarcophaga bullata, suggesting that calcium-mediated cold sensing is a general feature of insects. Our results imply that insect tissues use calcium signaling to instantly detect decreases in temperature and trigger downstream cold-hardening mechanisms.

  5. Sperm treatment affects capacitation parameters and penetration ability of ejaculated and epididymal boar spermatozoa.

    Science.gov (United States)

    Matás, C; Sansegundo, M; Ruiz, S; García-Vázquez, F A; Gadea, J; Romar, R; Coy, P

    2010-11-01

    This work was designed to study how this ability is affected by different sperm treatments routinely used for in vitro fertilization (IVF) assay. In this study, boar sperm samples from epididymal or ejaculated origin were processed by three different methods: left unwashed (NW group), washed in Dulbecco's phosphate-buffered saline supplemented with 0.1% BSA (BSA group), and washed on a Percoll(®) gradient (PERCOLL group). After preparation of semen samples, changes in motility patterns were studied by CASA, calcium uptake by spectrofluorimetry, and ROS generation, spontaneous acrosome reaction, and lipid disorder by means of flow cytometry. Finally IVF assays were also performed with the different semen samples and penetrability results evaluated at 2 and 4 h post insemination (hpi). Independently of the sperm treatment, epididymal spermatozoa showed higher values of progressive motility, percentage of live cells with low lipid disorder, and penetration ability at 4 hpi than the corresponding ejaculated spermatozoa. Ejaculated spermatozoa showed higher levels of calcium uptake, ROS generation and percentage of spontaneous acrosome reaction than epididymal sperm. Regarding sperm treatments, PERCOLL group showed the highest values for some motility parameters (linearity of the curvilinear trajectory, straightness, and average path velocity/curvilinear velocity), ROS generation and penetration ability at 2 and 4 hpi; however this same group showed the lowest values for sperm curvilinear velocity and lateral head displacement. From all experimental groups, ejaculated-PERCOLL-treated spermatozoa showed the highest fertilization ability after 2 hpi. Results suggest that capacitation pathways can be regulated by suitable treatments making the ejaculated sperm able to reach capacitation and fertilize oocytes in similar levels than epididymal spermatozoa, although most of the studied capacitation-associated changes do not correlate with this ability. PMID:20688369

  6. Evaluation of EHD films by electrical capacitance

    Science.gov (United States)

    Jablonka, Karolina; Glovnea, Romeo; Bongaerts, Jeroen

    2012-09-01

    The elastohydrodynamic (EHD) lubrication regime occurs in many machine elements where a combination of hydrodynamic effect, elastic deformation of the loaded surfaces and increase in the viscosity of the lubricant with pressure ensures the formation of a very thin, but continuous film of lubricant separating the contacting surfaces. Electrical methods to determine this film's thickness have preceded optical methods, which are widely used today. Although they generally give more qualitative thickness information, electrical methods have the main advantage that they can be applied to metallic contacts in machines, which makes them useful tools in the study of elastohydrodynamically lubricated contacts. This paper is part of a larger study on the application of electrical capacitance for the evaluation of film formation in EHD contacts. The main focus is on the quantitative measurements of film thickness using electrical capacitance. A new approach allowing the lubricant film thickness to be extracted from the measured capacitance is developed using a chromium-coated glass disc and subsequently applied to a steel-on-steel contact. The results show good agreement with optical measurements and theoretical models over a range of film thickness.

  7. Multi-Channel Capacitive Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Bingnan Wang

    2016-01-01

    Full Text Available In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved.

  8. Carbon Materials for Chemical Capacitive Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Y.; Dou, Y.; Zhao, D.; Fulvio, P. F.; Mayes, R. T.; Dai, S.

    2011-09-26

    Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.

  9. Carbon materials for chemical capacitive energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Yunpu; Zhao, Dongyuan [Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Key Laboratory of Molecular Engineering of Polymers of the Chinese, Ministry of Education, Laboratory of Advanced Materials, Fudan University, Shanghai (China); Dou, Yuqian [Department of Chemistry, Northeastern University, Shenyang (China); Fulvio, Pasquale F.; Mayes, Richard T.; Dai, Sheng [Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2011-11-09

    Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Multi-Channel Capacitive Sensor Arrays.

    Science.gov (United States)

    Wang, Bingnan; Long, Jiang; Teo, Koon Hoo

    2016-01-01

    In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved. PMID:26821023

  11. Effect of astaxanthin on human sperm capacitation.

    Science.gov (United States)

    Donà, Gabriella; Kožuh, Ivana; Brunati, Anna Maria; Andrisani, Alessandra; Ambrosini, Guido; Bonanni, Guglielmo; Ragazzi, Eugenio; Armanini, Decio; Clari, Giulio; Bordin, Luciana

    2013-06-01

    In order to be able to fertilize oocytes, human sperm must undergo a series of morphological and structural alterations, known as capacitation. It has been shown that the production of endogenous sperm reactive oxygen species (ROS) plays a key role in causing cells to undergo a massive acrosome reaction (AR). Astaxanthin (Asta), a photo-protective red pigment belonging to the carotenoid family, is recognized as having anti-oxidant, anti-cancer, anti-diabetic and anti-inflammatory properties and is present in many dietary supplements. This study evaluates the effect of Asta in a capacitating buffer which induces low ROS production and low percentages of acrosome-reacted cells (ARC). Sperm cells were incubated in the presence or absence of increasing concentrations of Asta or diamide (Diam) and analyzed for their ROS production, Tyr-phosphorylation (Tyr-P) pattern and percentages of ARC and non-viable cells (NVC). Results show that Asta ameliorated both sperm head Tyr-P and ARC values without affecting the ROS generation curve, whereas Diam succeeded in enhancing the Tyr-P level but only of the flagellum without increasing ARC values. It is suggested that Asta can be inserted in the membrane and therefore create capacitation-like membrane alteration which allow Tyr-P of the head. Once this has occurred, AR can take place and involves a higher numbers of cells. PMID:23736766

  12. Effect of Astaxanthin on Human Sperm Capacitation

    Directory of Open Access Journals (Sweden)

    Luciana Bordin

    2013-06-01

    Full Text Available In order to be able to fertilize oocytes, human sperm must undergo a series of morphological and structural alterations, known as capacitation. It has been shown that the production of endogenous sperm reactive oxygen species (ROS plays a key role in causing cells to undergo a massive acrosome reaction (AR. Astaxanthin (Asta, a photo-protective red pigment belonging to the carotenoid family, is recognized as having anti-oxidant, anti-cancer, anti-diabetic and anti-inflammatory properties and is present in many dietary supplements. This study evaluates the effect of Asta in a capacitating buffer which induces low ROS production and low percentages of acrosome-reacted cells (ARC. Sperm cells were incubated in the presence or absence of increasing concentrations of Asta or diamide (Diam and analyzed for their ROS production, Tyr-phosphorylation (Tyr-P pattern and percentages of ARC and non-viable cells (NVC. Results show that Asta ameliorated both sperm head Tyr-P and ARC values without affecting the ROS generation curve, whereas Diam succeeded in enhancing the Tyr-P level but only of the flagellum without increasing ARC values. It is suggested that Asta can be inserted in the membrane and therefore create capacitation-like membrane alteration which allow Tyr-P of the head. Once this has occurred, AR can take place and involves a higher numbers of cells.

  13. Capacitive Structures for Gas and Biological Sensing

    KAUST Repository

    Sapsanis, Christos

    2015-04-01

    The semiconductor industry was benefited by the advances in technology in the last decades. This fact has an impact on the sensors field, where the simple transducer was evolved into smart miniaturized multi-functional microsystems. However, commercially available gas and biological sensors are mostly bulky, expensive, and power-hungry, which act as obstacles to mass use. The aim of this work is gas and biological sensing using capacitive structures. Capacitive sensors were selected due to its design simplicity, low fabrication cost, and no DC power consumption. In the first part, the dominant structure among interdigitated electrodes (IDEs), fractal curves (Peano and Hilbert) and Archimedean spiral was investigated from capacitance density perspective. The investigation consists of geometrical formula calculations, COMSOL Multiphysics simulations and cleanroom fabrication of the capacitors on a silicon substrate. Moreover, low-cost fabrication on flexible plastic PET substrate was conducted outside cleanroom with rapid prototyping using a maskless laser etching. The second part contains the humidity, Volatile Organic compounds (VOCs) and Ammonia sensing of polymers, Polyimide and Nafion, and metal-organic framework (MOF), Cu(bdc)2.xH2O using IDEs and tested in an automated gas setup for experiment control and data extraction. The last part includes the biological sensing of C - reactive protein (CRP) quantification, which is considered as a biomarker of being prone to cardiac diseases and Bovine serum albumin (BSA) protein quantification, which is used as a reference for quantifying unknown proteins.

  14. Elucidation of the involvement of p14, a sperm protein during maturation, capacitation and acrosome reaction of caprine spermatozoa.

    Directory of Open Access Journals (Sweden)

    Pinki Nandi

    Full Text Available Mammalian sperm capacitation is an essential prerequisite to fertilization. Although progress is being made in understanding the physiology and biochemistry of capacitation, little has been yet explored about the potential role(s of individual sperm cell protein during this process. Therefore elucidation of the role of different sperm proteins in the process of capacitation might be of great importance to understand the process of fertilization. The present work describes the partial characterization of a 14-kDa protein (p14 detected in goat spermatozoa using an antibody directed against the purified protein. Confocal microscopic analysis reveals that the protein is present in both the intracellular and extracellular regions of the acrosomal and postacrosomal portion of caudal sperm head. Though subcellular localization shows that p14 is mainly cytosolic, however it is also seen to be present in peripheral plasma membrane and soluble part of acrosome. Immuno-localization experiment shows change in the distribution pattern of this protein upon induction of capacitation in sperm cells. Increased immunolabeling in the anterior head region of live spermatozoa is also observed when these cells are incubated under capacitating conditions, whereas most sperm cells challenged with the calcium ionophore A23187 to acrosome react, lose their labeling almost completely. Intracellular distribution of p14 also changes significantly during acrosome reaction. Interestingly, on the other hand the antibody raised against this 14-kDa sperm protein enhances the forward motility of caprine sperm cells. Rose-Bengal staining method shows that this anti-p14 antibody also decreases the number of acrosome reacted cells if incubated with capacitated sperm cells before induction of acrosome reaction. All these results taken together clearly indicate that p14 is intimately involved and plays a critical role in the acrosomal membrane fusion event.

  15. Calcium and Mitosis

    Science.gov (United States)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  16. Membongkar Akuntansi Double Entry Systems

    Directory of Open Access Journals (Sweden)

    Whedy Prasetyo

    2013-08-01

    Full Text Available Double entry isa process of recording transactions that always involve at least two accounts ofwhich changes (increases or decreases have consequences to maintain a balance equation. This is a simple basic accounting, that the use of the funds must alwaysbe equal to the acquisition of funds. The equation is not able to include some business events that are responses to the development of business environment. A proposed view is based on the interaction of researcher (New Bond with accountant (Mrs M to dismantle the double entry accounting through Maurice Merleau Ponty's approach (1906-1961. The results prove that physical aspects of knowledge willcontinue to evolve according to environmental interactions.

  17. Reduced calcium-dependent mitochondrial damage underlies the reduced vulnerability of excitotoxicity-tolerant hippocampal neurons.

    Science.gov (United States)

    Pivovarova, Natalia B; Stanika, Ruslan I; Watts, Charlotte A; Brantner, Christine A; Smith, Carolyn L; Andrews, S Brian

    2008-03-01

    In central neurons, over-stimulation of NMDA receptors leads to excessive mitochondrial calcium accumulation and damage, which is a critical step in excitotoxic death. This raises the possibility that low susceptibility to calcium overload-induced mitochondrial damage might characterize excitotoxicity-resistant neurons. In this study, we have exploited two complementary models of preconditioning-induced excitotoxicity resistance to demonstrate reduced calcium-dependent mitochondrial damage in NMDA-tolerant hippocampal neurons. We have further identified adaptations in mitochondrial calcium handling that account for enhanced mitochondrial integrity. In both models, enhanced tolerance was associated with improved preservation of mitochondrial membrane potential and structure. In the first model, which exhibited modest neuroprotection, mitochondria-dependent calcium deregulation was delayed, even though cytosolic and mitochondrial calcium loads were quantitatively unchanged, indicating that enhanced mitochondrial calcium capacity accounts for reduced injury. In contrast, the second model, which exhibited strong neuroprotection, displayed further delayed calcium deregulation and reduced mitochondrial damage because downregulation of NMDA receptor surface expression depressed calcium loading. Reducing calcium entry also modified the chemical composition of the calcium-buffering precipitates that form in calcium-loaded mitochondria. It thus appears that reduced mitochondrial calcium loading is a major factor underlying the robust neuroprotection seen in highly tolerant cells. PMID:18036152

  18. Calcium en cardioplegie

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Meijler, F.L.

    1985-01-01

    Coronary perfusion with a calcium-free solution, followed by reperfusion with a calcium containing solution, may result in acute myocardial cell death and in irreversible loss of the e1ectrical and mechanical activity of the heart. This phenomenon is known as the calcium paradox. A number of cardiop

  19. Distributed Capacitive Sensor for Sample Mass Measurement

    Science.gov (United States)

    Toda, Risaku; McKinney, Colin; Jackson, Shannon P.; Mojarradi, Mohammad; Manohara, Harish; Trebi-Ollennu, Ashitey

    2011-01-01

    Previous robotic sample return missions lacked in situ sample verification/ quantity measurement instruments. Therefore, the outcome of the mission remained unclear until spacecraft return. In situ sample verification systems such as this Distributed Capacitive (DisC) sensor would enable an unmanned spacecraft system to re-attempt the sample acquisition procedures until the capture of desired sample quantity is positively confirmed, thereby maximizing the prospect for scientific reward. The DisC device contains a 10-cm-diameter pressure-sensitive elastic membrane placed at the bottom of a sample canister. The membrane deforms under the weight of accumulating planetary sample. The membrane is positioned in close proximity to an opposing rigid substrate with a narrow gap. The deformation of the membrane makes the gap narrower, resulting in increased capacitance between the two parallel plates (elastic membrane and rigid substrate). C-V conversion circuits on a nearby PCB (printed circuit board) provide capacitance readout via LVDS (low-voltage differential signaling) interface. The capacitance method was chosen over other potential approaches such as the piezoelectric method because of its inherent temperature stability advantage. A reference capacitor and temperature sensor are embedded in the system to compensate for temperature effects. The pressure-sensitive membranes are aluminum 6061, stainless steel (SUS) 403, and metal-coated polyimide plates. The thicknesses of these membranes range from 250 to 500 m. The rigid substrate is made with a 1- to 2-mm-thick wafer of one of the following materials depending on the application requirements glass, silicon, polyimide, PCB substrate. The glass substrate is fabricated by a microelectromechanical systems (MEMS) fabrication approach. Several concentric electrode patterns are printed on the substrate. The initial gap between the two plates, 100 m, is defined by a silicon spacer ring that is anodically bonded to the glass

  20. Calcium--a central regulator of keratinocyte differentiation in health and disease.

    Science.gov (United States)

    Elsholz, Floriana; Harteneck, Christian; Muller, Walter; Friedland, Kristina

    2014-01-01

    Regular keratinocyte differentiation is crucial for the formation of an intact epidermal barrier and is triggered by extracellular calcium. Disturbances of epidermal barrier formation and aberrant keratinocyte differentiation are involved in the pathophysiology of several skin diseases, such as psoriasis, atopic dermatitis, basal and squamous skin cancer, and genetic skin diseases such as Darier's disease and Olmstedt syndrome. In this review, we summarize current knowledge about the underlying molecular mechanisms of calcium-induced differentiation in keratinocytes. We provide an overview of calcium's genomic and non-genomic mechanisms to induce differentiation and discuss the calcium gradient in the epidermis, giving rise to cornified skin and lipid envelope formation. We focus on the calcium-sensing receptor, transient receptor potential channels, and STIM/Orai as the major constituents of calcium sensing and calcium entry in the keratinocytes. Finally, skin diseases linked to impaired differentiation will be discussed, paying special attention to disturbed TRP channel expression and TRP channel mutations.

  1. Improved capacitance sensor with variable operating frequency for scanning capacitance microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Joonhyung [PSIA Corporation, Induspia 5F, Sang-Daewon-Dong 517-13, Sungnam 462-120 (Korea, Republic of); Kim, Joonhui [PSIA Corporation, Induspia 5F, Sang-Daewon-Dong 517-13, Sungnam 462-120 (Korea, Republic of); Jeong, Jong-Hwa [PSIA Corporation, Induspia 5F, Sang-Daewon-Dong 517-13, Sungnam 462-120 (Korea, Republic of); Lee, Euy-Kyu [Department of Physics, Myongji University, Yongin, Kyunggido 449-728 (Korea, Republic of); Seok Kim, Yong [PSIA Corporation, Induspia 5F, Sang-Daewon-Dong 517-13, Sungnam 462-120 (Korea, Republic of); Kang, Chi Jung [Department of Physics, Myongji University, Yongin, Kyunggido 449-728 (Korea, Republic of); Park, Sang-il [PSIA Corporation, Induspia 5F, Sang-Daewon-Dong 517-13, Sungnam 462-120 (Korea, Republic of)]. E-mail: park@psia.co.kr

    2005-11-15

    Scanning capacitance microscopy (SCM) has been gaining attention for its capability to measure local electrical properties in doping profile, oxide thickness, trapped charges and charge dynamics. In many cases, stray capacitance produced by different samples and measurement conditions affects the resonance frequency of a capacitance sensor. The applications of conventional SCM are critically limited by the fixed operating frequency and lack of tunability in its SCM sensor. In order to widen SCM application to various samples, we have developed a novel SCM sensor with variable operating frequency. By performing variable frequency sweep over the band of 160 MHz, the SCM sensor is tuned to select the best and optimized resonance frequency and quality factor for each sample measurement. The fundamental advantage of the new variable frequency SCM sensor was demonstrated in the SCM imaging of silicon oxide nano-crystals. Typical sensitivity of the variable frequency SCM sensor was found to be 10{sup -19} F/V.

  2. Improved capacitance sensor with variable operating frequency for scanning capacitance microscopy

    International Nuclear Information System (INIS)

    Scanning capacitance microscopy (SCM) has been gaining attention for its capability to measure local electrical properties in doping profile, oxide thickness, trapped charges and charge dynamics. In many cases, stray capacitance produced by different samples and measurement conditions affects the resonance frequency of a capacitance sensor. The applications of conventional SCM are critically limited by the fixed operating frequency and lack of tunability in its SCM sensor. In order to widen SCM application to various samples, we have developed a novel SCM sensor with variable operating frequency. By performing variable frequency sweep over the band of 160 MHz, the SCM sensor is tuned to select the best and optimized resonance frequency and quality factor for each sample measurement. The fundamental advantage of the new variable frequency SCM sensor was demonstrated in the SCM imaging of silicon oxide nano-crystals. Typical sensitivity of the variable frequency SCM sensor was found to be 10-19 F/V

  3. Components of Visual Prior Entry

    Science.gov (United States)

    Schneider, Keith A.; Bavelier, Daphne

    2003-01-01

    The prior entry hypothesis contends that attention accelerates sensory processing, shortening the time to perception. Typical observations supporting the hypothesis may be explained equally well by response biases, changes in decision criteria, or sensory facilitation. In a series of experiments conducted to discriminate among the potential…

  4. Entry Facilitation by Environmental Groups

    NARCIS (Netherlands)

    van der Made, Allard; Schoonbeek, Lambert

    2009-01-01

    We consider a model of vertical product differentiation where consumers care about the environmental damage their consumption causes. An environmental group is capable of increasing consumers' environmental concern via a costly campaign. We show that the prospect of such a campaign can induce entry

  5. Delayed School Entry in Uganda

    Science.gov (United States)

    Moyi, Peter

    2011-01-01

    Since 1997 Uganda has seen a large increase in school enrolment. Despite this increased enrolment, universal education has remained elusive. Many children enrol in school, but not at the recommended age, and they drop out before completing school. This article focuses on one of these problems--delayed school entry. What household factors are…

  6. [Roles of intracellular calcium and monomeric G-proteins in regulating exocytosis of human neutrophils].

    Science.gov (United States)

    Zhu, Ying; Wang, Jun-Han; Wu, Jian-Min; Xu, Tao; Zhang, Chun-Guang

    2003-12-25

    Neutrophils play a major role in host defense against microbial infection. There are some clues indicate that neutrophils may also play a role in the pathophysiology of the airway obstruction in chronic asthma. We studied the roles of intracellular calcium and GTP gamma S in the regulation of neutrophils exocytosis using pipette perfusion and membrane capacitance measurement technique in whole cell patch clamp configuration. The results showed that the membrane capacitance increase induced by calcium revealed a biphasic process. The first phase occurred when the calcium level was between 0.2-14 micromol/L with a plateau amplitude of 1.23 pF and a calcium EC50 of 1.1 micromol/L. This phase might correspond to the release of the tertiary granules. The second phase occurred when the calcium concentration was between 20-70 micromol/L with a plateau increment of 6.36 pF, the calcium EC50 being about 33 micromol/L. This phase might represent the release of the primary and secondary granules. Intracellular calcium also simultaneously increased the exocytotic rate and the eventual extent in neutrophils. On the other hand, GTP gamma S can increase the exocytotic rate in a dose-dependent manner but had no effect on the eventual extent of membrane capacitance increment (>6 pF) if the cell was stimulated for a long period (>20 min). GTP gamma S (ranging from 20 to 100 micromol/L) induced the neutrophils to release all four types of the granules at very low intracellular calcium level. PMID:14695488

  7. Calcium signaling and epilepsy.

    Science.gov (United States)

    Steinlein, Ortrud K

    2014-08-01

    Calcium signaling is involved in a multitude of physiological and pathophysiological mechanisms. Over the last decade, it has been increasingly recognized as an important factor in epileptogenesis, and it is becoming obvious that the excess synchronization of neurons that is characteristic for seizures can be linked to various calcium signaling pathways. These include immediate effects on membrane excitability by calcium influx through ion channels as well as delayed mechanisms that act through G-protein coupled pathways. Calcium signaling is able to cause hyperexcitability either by direct modulation of neuronal activity or indirectly through calcium-dependent gliotransmission. Furthermore, feedback mechanisms between mitochondrial calcium signaling and reactive oxygen species are able to cause neuronal cell death and seizures. Unravelling the complexity of calcium signaling in epileptogenesis is a daunting task, but it includes the promise to uncover formerly unknown targets for the development of new antiepileptic drugs.

  8. Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels.

    Directory of Open Access Journals (Sweden)

    Tamas Szikra

    Full Text Available Calcium is a messenger ion that controls all aspects of cone photoreceptor function, including synaptic release. The dynamic range of the cone output extends beyond the activation threshold for voltage-operated calcium entry, suggesting another calcium influx mechanism operates in cones hyperpolarized by light. We have used optical imaging and whole-cell voltage clamp to measure the contribution of store-operated Ca(2+ entry (SOCE to Ca(2+ homeostasis and its role in regulation of neurotransmission at cone synapses. Mn(2+ quenching of Fura-2 revealed sustained divalent cation entry in hyperpolarized cones. Ca(2+ influx into cone inner segments was potentiated by hyperpolarization, facilitated by depletion of intracellular Ca(2+ stores, unaffected by pharmacological manipulation of voltage-operated or cyclic nucleotide-gated Ca(2+ channels and suppressed by lanthanides, 2-APB, MRS 1845 and SKF 96365. However, cation influx through store-operated channels crossed the threshold for activation of voltage-operated Ca(2+ entry in a subset of cones, indicating that the operating range of inner segment signals is set by interactions between store- and voltage-operated Ca(2+ channels. Exposure to MRS 1845 resulted in approximately 40% reduction of light-evoked postsynaptic currents in photopic horizontal cells without affecting the light responses or voltage-operated Ca(2+ currents in simultaneously recorded cones. The spatial pattern of store-operated calcium entry in cones matched immunolocalization of the store-operated sensor STIM1. These findings show that store-operated channels regulate spatial and temporal properties of Ca(2+ homeostasis in vertebrate cones and demonstrate their role in generation of sustained excitatory signals across the first retinal synapse.

  9. Numerical analysis of capacitive pressure micro-sensors

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiaomin; LI; Mingxuan; WANG; Chenghao

    2005-01-01

    Pseudo-spectral method is used to numerically model the diaphragm deflection of capacitive pressure micro-sensor under uniform load. The relationship between the capacitance of the micro-sensor and the load is then analyzed after the description of the computational principle. For normal mode micro-sensor, the tensile force on the diaphragm can be ignored and thereby the capacitance increases linearly with the load increase only when the load is so small that the resultant deflection is less than the diaphragm thickness. The linear relationship between the capacitance and the load turns to be nonlinear thereafter and the capacitance rises dramatically with the constant increase of the load. For touch mode micro-sensor, an algorithm to determine the touch radius of the diaphragm and substrate is presented and the curve of capacitance versus load is shown on the numerical results laying a theoretical foundation for micro-sensor design.

  10. The Timothy syndrome mutation differentially affects voltage- and calcium-dependent inactivation of CaV1.2 L-type calcium channels

    OpenAIRE

    Barrett, Curtis F.; Tsien, Richard W.

    2008-01-01

    Calcium entry into excitable cells is an important physiological signal, supported by and highly sensitive to the activity of voltage-gated Ca2+ channels. After membrane depolarization, Ca2+ channels first open but then undergo various forms of negative feedback regulation including voltage- and calcium-dependent inactivation (VDI and CDI, respectively). Inactivation of Ca2+ channel activity is perturbed in a rare yet devastating disorder known as Timothy syndrome (TS), whose features include...

  11. Accurate sizing of supercapacitors storage system considering its capacitance variation.

    OpenAIRE

    Trieste, Sony; Bourguet, Salvy; Olivier, Jean-Christophe; Loron, Luc; Le Claire, Jean-Claude

    2011-01-01

    This paper highlights the energy errors made for the design of supercapacitors used as a main energy source. First of all, the paper presents the two definitions of capacitance of a capacitance-voltage dependent material. The number of supercapacitors is important for the application purchasing cost. That is why the paper introduces an analytical model and an electrical model along with an identification method for the capacitance variation. This variation is presented and compared to the man...

  12. Nonlinear dynamics of capacitive charging and desalination by porous electrodes

    OpenAIRE

    Biesheuvel, P. M.; Bazant, M.Z.

    2010-01-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by super-capacitors, water desalination and purification by capacitive deionization (or desalination), and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or spec...

  13. Probing Quantum Capacitance in a 3D Topological Insulator

    OpenAIRE

    Kozlov, D. A.; Bauer, Dominik; Ziegler, Johannes; Fischer, Ralf, 1965-; Savchenko, M. L.; Kvon, Z.D.; Mikhailov, N. N.; Dvoretsky, S. A.; Weiss, Dieter

    2016-01-01

    We measure the quantum capacitance and probe thus directly the electronic density of states of the high mobility, Dirac type of two-dimensional electron system, which forms on the surface of strained HgTe. Here we show that observed magneto-capacitance oscillations probe, in contrast to magnetotransport, primarily the top surface. Capacitance measurements constitute thus a powerful tool to probe only one topological surface and to reconstruct its Landau level spectrum for different positions ...

  14. DEVELOPMENT OF ADAPTED CAPACITANCE MANOMETER FOR  THERMOSPHERIC APPLICATIONS

    OpenAIRE

    Orr, Cameron Scott

    2016-01-01

    An adapted capacitance manometer is a sensor composed of one fixed plate and one movable plate that is able to make accurate pressure measurements in a low pressure environment. Using detection circuitry, a change in capacitance between the two plates can be measured and correlated to a differential pressure. First, a high sensitivity manometer is produced that exhibits a measurable change in capacitance when experiencing a pressure differential in a low pressure space environment. Second,...

  15. Static and Motional Feedthrough Capacitance of Flexural Microresonator

    OpenAIRE

    Wen-Teng Chang

    2011-01-01

    The present paper evaluates the static and motional feedthrough capacitance of a silicon carbide-based flexural-mode microelectromechanical system resonator. The static feedthrough capacitance was measured by a network analyzer under atmospheric pressure. The motional feedthrough was obtained by introducing various values into the modeling circuit in order to fit the Bode plots measured under reduced pressure. The static feedthrough capacitance was 0.02 pF, whereas the motional feedthrough ca...

  16. Capacitive position measurement for high-precision space inertial sensor

    Institute of Scientific and Technical Information of China (English)

    Yan-zheng BAI; Ze-bing ZHOU; Hai-bo TU; Shu-chao WU; Lin CAI; LI LIU; Jun LUO

    2009-01-01

    Low noise position measurement is fundamental for space inertial sensors, and at present the capacitive position sensor is widely employed for space inertial sensors. The design for the possible suppression of the front-end electric noises for a capacitive sensor is presented. A prototype capacitive sensor with 2x 10-6pF/Hzi/2 at frequency above 0.04 Hz is achieved and further improvements are discussed.

  17. Carrier Statistics and Quantum Capacitance Models of Graphene Nanoscroll

    Directory of Open Access Journals (Sweden)

    M. Khaledian

    2014-01-01

    schematic perfect scroll-like Archimedes spiral. The DOS model was derived at first, while it was later applied to compute the carrier concentration and quantum capacitance model. Furthermore, the carrier concentration and quantum capacitance were modeled for both degenerate and nondegenerate regimes, along with examining the effect of structural parameters and chirality number on the density of state and carrier concentration. Latterly, the temperature effect on the quantum capacitance was studied too.

  18. CMOS MEMS capacitive absolute pressure sensor

    International Nuclear Information System (INIS)

    This paper presents the design, fabrication and characterization of a capacitive pressure sensor using a commercial 0.18 µm CMOS (complementary metal–oxide–semiconductor) process and postprocess. The pressure sensor is capacitive and the structure is formed by an Al top electrode enclosed in a suspended SiO2 membrane, which acts as a movable electrode against a bottom or stationary Al electrode fixed on the SiO2 substrate. Both the movable and fixed electrodes form a variable parallel plate capacitor, whose capacitance varies with the applied pressure on the surface. In order to release the membranes the CMOS layers need to be applied postprocess and this mainly consists of four steps: (1) deposition and patterning of PECVD (plasma-enhanced chemical vapor deposition) oxide to protect CMOS pads and to open the pressure sensor top surface, (2) etching of the sacrificial layer to release the suspended membrane, (3) deposition of PECVD oxide to seal the etching holes and creating vacuum inside the gap, and finally (4) etching of the passivation oxide to open the pads and allow electrical connections. This sensor design and fabrication is suitable to obey the design rules of a CMOS foundry and since it only uses low-temperature processes, it allows monolithic integration with other types of CMOS compatible sensors and IC (integrated circuit) interface on a single chip. Experimental results showed that the pressure sensor has a highly linear sensitivity of 0.14 fF kPa−1 in the pressure range of 0–300 kPa. (paper)

  19. CMOS MEMS capacitive absolute pressure sensor

    Science.gov (United States)

    Narducci, M.; Yu-Chia, L.; Fang, W.; Tsai, J.

    2013-05-01

    This paper presents the design, fabrication and characterization of a capacitive pressure sensor using a commercial 0.18 µm CMOS (complementary metal-oxide-semiconductor) process and postprocess. The pressure sensor is capacitive and the structure is formed by an Al top electrode enclosed in a suspended SiO2 membrane, which acts as a movable electrode against a bottom or stationary Al electrode fixed on the SiO2 substrate. Both the movable and fixed electrodes form a variable parallel plate capacitor, whose capacitance varies with the applied pressure on the surface. In order to release the membranes the CMOS layers need to be applied postprocess and this mainly consists of four steps: (1) deposition and patterning of PECVD (plasma-enhanced chemical vapor deposition) oxide to protect CMOS pads and to open the pressure sensor top surface, (2) etching of the sacrificial layer to release the suspended membrane, (3) deposition of PECVD oxide to seal the etching holes and creating vacuum inside the gap, and finally (4) etching of the passivation oxide to open the pads and allow electrical connections. This sensor design and fabrication is suitable to obey the design rules of a CMOS foundry and since it only uses low-temperature processes, it allows monolithic integration with other types of CMOS compatible sensors and IC (integrated circuit) interface on a single chip. Experimental results showed that the pressure sensor has a highly linear sensitivity of 0.14 fF kPa-1 in the pressure range of 0-300 kPa.

  20. Modeling of progesterone-induced intracellular calcium signaling in human spermatozoa.

    Science.gov (United States)

    Li, Long-Fei; Xiang, Cheng; Zhu, Ya-Bing; Qin, Kai-Rong

    2014-06-21

    Calcium ion is a secondary messenger of mammalian spermatozoa. The dynamic change of its concentration plays a vital role in the process of sperm motility, capacitation, acrosome and fertilization. Progesterone released by the cumulus cells, as a potent stimulator of fertilization, can activate the calcium channels on the plasma membrane, which in turn triggers the dynamic change of intracellular calcium concentration. In this paper, a mathematical model of calcium dynamic response in mammalian spermatozoa induced by progesterone is proposed and numerical simulation of the dynamic model is conducted. The results show that the dynamic response of calcium concentration predicted by the model is in accordance with experimental evidence. The proposed dynamic model can be used to explain the phenomena observed in the experiments and predict new phenomena to be revealed by experimental investigations, which will provide the basis to quantitatively investigate the fluid mechanics and biochemistry for the sperm motility induced by progesterone.

  1. Capacitive tool standoff sensor for dismantlement tasks

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, D.J.; Weber, T.M. [Sandia National Labs., Albuquerque, NM (United States); Liu, J.C. [Univ. of Illinois, Urbana, IL (United States)

    1996-12-31

    A capacitive sensing technology has been applied to develop a Standoff Sensor System for control of robotically deployed tools utilized in Decontamination and Dismantlement (D and D) activities. The system combines four individual sensor elements to provide non-contact, multiple degree-of-freedom control of tools at distances up to five inches from a surface. The Standoff Sensor has been successfully integrated to a metal cutting router and a pyrometer, and utilized for real-time control of each of these tools. Experiments demonstrate that the system can locate stationary surfaces with a repeatability of 0.034 millimeters.

  2. Capacitive tool standoff sensor for dismantlement tasks

    International Nuclear Information System (INIS)

    A capacitive sensing technology has been applied to develop a Standoff Sensor System for control of robotically deployed tools utilized in Decontamination and Dismantlement (D and D) activities. The system combines four individual sensor elements to provide non-contact, multiple degree-of-freedom control of tools at distances up to five inches from a surface. The Standoff Sensor has been successfully integrated to a metal cutting router and a pyrometer, and utilized for real-time control of each of these tools. Experiments demonstrate that the system can locate stationary surfaces with a repeatability of 0.034 millimeters

  3. 3-D capacitance density imaging system

    Science.gov (United States)

    Fasching, G.E.

    1988-03-18

    A three-dimensional capacitance density imaging of a gasified bed or the like in a containment vessel is achieved using a plurality of electrodes provided circumferentially about the bed in levels and along the bed in channels. The electrodes are individually and selectively excited electrically at each level to produce a plurality of current flux field patterns generated in the bed at each level. The current flux field patterns are suitably sensed and a density pattern of the bed at each level determined. By combining the determined density patterns at each level, a three-dimensional density image of the bed is achieved. 7 figs.

  4. Bi-weekly waterfowl survey data entry

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Data sheet for the entry of bi-weekly waterfowl survey data from the state of Kansas. This Excel file contains the data entry sheet and a chart displaying waterfowl...

  5. Smoking, calcium, calcium antagonists, and aging.

    Science.gov (United States)

    Nicita-Mauro, V

    1990-01-01

    Aging is characterized, besides other changes, by a progressive increase in calcium content in the arterial wall, which is enhanced by diabetes mellitus, osteoporosis, arterial hypertension, and tabagism. As to tabagism, experiments in animals have shown that nicotine can increase calcium content of the arterial wall, and clinical studies have demonstrated that cigarette smoking induces peripheral vasoconstriction, with consequent increase in blood pressure levels. In order to study the role of calcium ions in the pathogenesis of the vasoconstrictive lesions caused by "acute" smoking, the author has studied the peripheral vascular effects of the calcium-channel antagonist nifedipine, a dihydropyridine derivative, and calcitonin, a hypocalcemizing hormone which possess vasoactive actions on 12 elderly regular smokers (mean age 65.8 years). The results demonstrated that both nifedipine (10 mg sublingually 20 min before smoking) and salmon calcitonin (100 MRC U/daily intramuscularly for three days) are able to prevent peripheral vasoconstriction evaluated by Doppler velocimetry, as well as the increase of blood pressure induced by smoking. On the basis of our results, the author proposes that cigarette smoking-induced vasoconstriction is a calcium-mediated process, which can be hindered by drugs with calcium antagonist action. PMID:2226675

  6. Human body capacitance: static or dynamic concept? [ESD

    DEFF Research Database (Denmark)

    Jonassen, Niels M

    1998-01-01

    A standing human body insulated from ground by footwear and/or floor covering is in principle an insulated conductor and has, as such, a capacitance, i.e. the ability to store a charge and possibly discharge the stored energy in a spark discharge. In the human body, the human body capacitance (HBC......) is traditionally chosen as 100 pF. However, a simple geometric model seems to suggest considerably higher values. A series of experiments, where the capacitance of standing persons were determined for various combinations of footwear and floor coverings, gave values in the order of 100-150 pF when the capacitance...

  7. Calibration of capacitive hydrostatic leveling sensors of NSRL

    International Nuclear Information System (INIS)

    The principle of capacitive hydrostatic leveling sensors was presented. Simulations of sensors with two kinds of materials (metal and distilled water) as target electrode in the situations of calibration and work were carried out by Ansoft Maxwell software. Different values of capacitances in different situations were compared and analyzed. Then some experiments were done with independently developed prototype of capacitive hydrostatic leveling sensors to verify the above simulations. In the situations of calibration and work, the same property (conductivity and dielectric constant) material as target electrode should be chosen for capacitive hydrostatic leveling sensors. Otherwise, there is an error of sensors after calibration, and the main factor is conductivity. (authors)

  8. Variable-capacitance tachometer eliminates troublesome magnetic fields

    Science.gov (United States)

    1966-01-01

    Dual variable-capacitance tachometer measures angular speed and sense of rotation without magnetic components. Thus it eliminates magnetic flux interference with associated instrumentation in an electromechanical system.

  9. Quantum capacitance of graphene in contact with metal

    International Nuclear Information System (INIS)

    We report a versatile computation method to quantitatively determine the quantum capacitance of graphene when it is in contact with metal. Our results bridge the longstanding gap between the theoretically predicted and experimentally measured quantum capacitance of graphene. Contrary to popular assumptions, the presence of charged impurities or structural distortions of graphene are not the only sources of the asymmetric capacitance with respect to the polarity of the bias potential and the higher-than-expected capacitance at the Dirac point. They also originate from the field-induced electronic interactions between graphene and metal. We also provide an improved model representation of a metal–graphene junction

  10. Calcium absorption and achlorhydria

    International Nuclear Information System (INIS)

    Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement

  11. Sunk Costs and Antitrust Barriers to Entry

    OpenAIRE

    SCHMALENSEE, Richard

    2004-01-01

    US antitrust policy takes as its objective consumer welfare, not total economic welfare. With that objective, Joe Bain's definition of entry barriers is more useful than George Stigler's or definitions based on economic welfare. It follows that economies of scale that involve sunk costs may create antitrust barriers to entry. A simple model shows that sunk costs without scale economies may discourage entry without creating an antitrust entry barrier.

  12. Endogenous Market Structure and Foreign Market Entry

    OpenAIRE

    Markusen, James R.; Frank Stähler

    2009-01-01

    Models dealing with cross-border acquisitions versus greenfield investment usually assume that the entry of a foreign firm into a market has effects on the outputs of all domestic firms in that market, but exit or entry of local firms is not considered. The purpose of this paper is to re-examine the acquisition versus greenfield versus exporting question under fixed versus free entry assumptions for local firms. Our finding is that greenfield entry and exporting options are more attractive re...

  13. 19 CFR 122.42 - Aircraft entry.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Aircraft entry. 122.42 Section 122.42 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY AIR COMMERCE REGULATIONS Aircraft Entry and Entry Documents; Electronic Manifest Requirements...

  14. Sport entries and qualification manual: Nanjing 2014

    OpenAIRE

    2014-01-01

    Sport entries constitute an important part of the delegation registration process of the Nanjing 2014 Summer Youth Olympic Games. This manual aims to introduce to NOCs the process, relevant policies and requirements regarding sport entries so as to ensure that NOCs can successfully complete the entries for their athletes to the Nanjing 2014 Youth Olympic Games.

  15. Flavivirus Entry Receptors: An Update

    Directory of Open Access Journals (Sweden)

    Manuel Perera-Lecoin

    2013-12-01

    Full Text Available Flaviviruses enter host cells by endocytosis initiated when the virus particles interact with cell surface receptors. The current model suggests that flaviviruses use at least two different sets of molecules for infectious entry: attachment factors that concentrate and/or recruit viruses on the cell surface and primary receptor(s that bind to virions and direct them to the endocytic pathway. Here, we present the currently available knowledge regarding the flavivirus receptors described so far with specific attention to C-type lectin receptors and the phosphatidylserine receptors, T-cell immunoglobulin and mucin domain (TIM and TYRO3, AXL and MER (TAM. Their role in flavivirus attachment and entry as well as their implication in the virus biology will be discussed in depth.

  16. Developing the Brand Entry Strategy

    OpenAIRE

    Gupta, Pramesh

    2004-01-01

    With more than two decades of experience in the flashlight industry, Vinpol is all set to launch the flashlights, under their brand name, into the market. This dissertation describes a process of generating a brand entry strategy for Vinpol. A model is proposed that adapts the approach of 4Ps and Relationship Marketing. The rationale for this report has come about due to initial secondary research which shows that there will be constant growth in the flashlight industry. Some factors that nee...

  17. Marketing Mix Reactions to Entry

    OpenAIRE

    Robinson, William T.

    1988-01-01

    Initial product, distribution, marketing expenditure, and price reactions by incumbents are examined for 115 entrants into oligopolistic markets. The most common reaction pattern is either no reaction or only a single reaction. It is very unusual for entrants to face reactions across the entire marketing mix. Reactions in the first two years after entry are explained as a function of the entrant's strategy, incumbent characteristics, and industry characteristics. The explanation provides insi...

  18. Nanostructured conducting polymer based reagentless capacitive immunosensor.

    Science.gov (United States)

    Bandodkar, Amay Jairaj; Dhand, Chetna; Arya, Sunil K; Pandey, M K; Malhotra, Bansi D

    2010-02-01

    Nanostructured polyaniline (PANI) film electrophoretically fabricated onto indium-tin-oxide (ITO) coated glass plate has been utilized for development of an immunosensor based on capacitance change of a parallel plate capacitor (PPC) by covalently immobilizing anti-human IgG (Anti-HIgG) using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide chemistry. These fabricated PANI/ITO and Anti-HIgG/PANI/ITO plates have been characterized using scanning electron microscopy, cyclic voltammetry, differential pulse voltammetry and Fourier transform infra-red studies. The capacitance measurements indicate that dielectric medium of this biologically modified PPC (Anti-HIgG/PANI/ITO) is sensitive to HIgG in 5 - 5 x 10(5) ng mL(-1) range and has lower detection limit of 1.87 ng mL(-1). The observed results reveal that this Anti-HIgG modified PPC can be used as a robust, easy-to-use, reagentless, sensitive and selective immunosensor for estimation of human IgG.

  19. THERMAL DRIFT CHARACTERISTICS OF CAPACITIVE PRESSURE SENSORS

    Directory of Open Access Journals (Sweden)

    ABDELAZIZ BEDDIAF

    2016-03-01

    Full Text Available The capacitive pressure sensors based on silicon are characterized by their very high sensitivities and their low power consumption. Nevertheless, their thermal behavior remains more or less unpredictable because they can indicate very high thermal coefficients. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristics drift. In this study, we modeled the thermal behavior of this sensors, using Finite Element Analysis (FEA made in COMSOL. The model solved by COMSOL environment takes into account the entire sensor and thermal effects due to the temperature considering the materials’ properties, the geometric shape and also the heat transfer mechanisms. By COMSOL we determine how the temperature affects the sensor during the manufacturing process. For that end, we calculated the thermal drift of capacitance at rest, the thermal coefficients and we compared them with experimental results to validate our model. Further, we studied the thermal drift of sensor characteristics both at rest and under constant and uniform pressure. Further, our study put emphasis on the geometric influence parameters on these characteristics to optimize the sensor performance. Finally, this study allows us to predict the sensor behavior against temperature and to minimize this effect by optimizing the geometrical parameters.

  20. Proportional microvolume capacitive liquid level sensor array.

    Science.gov (United States)

    Seliskar, D; Waterbury, R; Kearney, R

    2005-01-01

    A sensor array has been developed for use with laboratory automation to permit closed-loop control of liquid levels in a multiwell microplate geometry. We extended a simple electrical model for non-contact capacitance-based fluid sensors to describe a fluid-level dependency. The new model shows that a charge-transfer based capacitance transducer, employing a liquid-specific calibration, can be used to obtain an output signal that varies linearly with the liquid level. The calibration also compensates for liquid-to-liquid conductivity and permittivity differences. A prototype 3×3 sensor array was built and tested using NaCl and ethanol solutions to simulate the range of conductivity and permittivity typical in biological and chemical research. Calibrated output signals were linear with liquid volume for all tested solutions (R2>0.92). Measurement error averaged 1.3 % (2.0 μl) with a standard deviation of 6.0% (9.0 μl). These results demonstrate the feasibility of developing a microvolume sensor array in essentially any M×N microplate geometry. PMID:17281955

  1. A capacitive electrode with fast recovery feature

    International Nuclear Information System (INIS)

    Capacitive electrodes (CEs) allow for acquiring biopotentials without galvanic contact, avoiding skin preparation and the use of electrolytic gel. The signal quality provided by present CEs is similar to that of standard wet electrodes, but they are more sensitive to electrostatic charge interference and motion artifacts, mainly when biopotentials are picked up through clothing and coupling capacitances are reduced to tens of picofarads. When artifacts are large enough to saturate the preamplifier, several seconds (up to tens) are needed to recover a proper baseline level, and during this period biopotential signals are irremediably lost. To reduce this problem, a CE that includes a fast-recovery (FR) circuit is proposed. It works directly on the coupling capacitor, recovering the amplifier from saturation while preserving ultra-high input impedance, as a CE requires. A prototype was built and tested acquiring ECG signals. Several experimental data are presented, which show that the proposed circuit significantly reduces record segment losses due to amplifier saturation when working in real environments. (paper)

  2. Measurements of intracellular calcium

    International Nuclear Information System (INIS)

    Intracellular calcium concentration ([Ca2+]i) has been measured in cultured cells by using Fura-2 load cells and a computer-controlled Perkin Elmer LS-5B spectrofluorometer. Increased [Ca2+]i in cells exposed to extracellular bilirubin was observed both with and without extracellular calcium. However, the increase was considerable larger with extracellular calcium. The enhancement of [Ca2+]i became smaller with decreasing bilirubin/BSA (bovine serum albumine) ratio. 5 refs., 5 figs

  3. Nonlinear dynamics of capacitive charging and desalination by porous electrodes

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Bazant, M.Z.

    2010-01-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by supercapacitors, water desalination and purification by capacitive deionization, and capacitive extraction of renewable energy from a salin

  4. Clean energy generation using capacitive electrodes in reverse electrodialysis

    NARCIS (Netherlands)

    Vermaas, D.A.; Bajracharya, S.; Bastos Sales, B.; Saakes, Michel; Hamelers, B.; Nijmeijer, D.C.

    2013-01-01

    Capacitive reverse electrodialysis (CRED) is a newly proposed technology to generate electricity from mixing of salt water and fresh water (salinity gradient energy) by using a membrane pile as in reverse electrodialysis (RED) and capacitive electrodes. The salinity difference between salt water and

  5. Large Capacitance Measurement by Multiple Uses of MBL Charge Sensor

    Science.gov (United States)

    Lee, Jung Sook; Chae, Min; Kim, Jung Bog

    2010-01-01

    A recent article by Morse described interesting electrostatics experiments using an MBL charge sensor. In this application, the charge sensor has a large capacitance compared to the charged test object, so nearly all charges can be transferred to the sensor capacitor from the capacitor to be measured. However, the typical capacitance of commercial…

  6. Electric field theory and the fallacy of void capacitance

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1991-01-01

    The concept of the capacitance of a gaseous void is discussed as applied to electrical insulation science. The most pertinent aspect of the capacitance definition is that of reference to a single-valued potential difference between surfaces. This implies that these surfaces must be surfaces...

  7. Polycrystalline VO2 film characterization by quantum capacitance measurement

    International Nuclear Information System (INIS)

    Capacitance measurement is performed using a home-built bridge on quasi two-dimensional vanadium dioxide films grown on silicon-dioxide/p-doped silicon substrates. Correlated effects appearing in the quantum capacitance are obtained as a function of temperature at low frequencies. The thermodynamic density of states reveals the opening band gap in the insulating monoclinic phase

  8. Traveling mirror compressor delay line with nonconstant capacitance

    OpenAIRE

    Bellan, P. M.

    1981-01-01

    The scaling relations for a traveling mirror magnetic compressor [P.M. Bellan, Phys. Rev. Lett. 43, 858 (1979)] having nonconstant capacitance are derived. Varying capacitance (rather than inductance) makes possible a lower impedance device, and hence, higher field levels or faster compression times.

  9. Capacitance tuning of nanoscale split-ring resonators

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Mortensen, Asger; Kristensen, Anders

    2009-01-01

    We investigate the capacitance tuning of nanoscale split-ring resonators. Based on a simple inductor-capacitor circuit model, we derive an expression, where the inductance is proportional to the area while the capacitance reflects the aspect ratio of the slit. The resonance frequency may thus...

  10. Capacitance tuning of nanoscale split-ring resonators

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Xiao, Sanshui; Mortensen, Niels Asger;

    2010-01-01

    In this paper, we investigate the capacitance tuning of nanoscale split-ring resonators. Based on a simple LC circuit model (LC-model), we derive an expression where the inductance is proportional to the area while the capacitance reflects the aspect ratio of the slit. The resonance frequency may...

  11. Binding of Adenovirus Capsid to Dipalmitoyl Phosphatidylcholine Provides a Novel Pathway for Virus Entry

    OpenAIRE

    Balakireva, Larissa; Schoehn, Guy; Thouvenin, Eric; Chroboczek, Jadwiga

    2003-01-01

    Adenovirus (Ad) is an airborne, nonenveloped virus infecting respiratory epithelium. To study the mechanism of Ad entry, we used alveolar adenocarcinoma A549 cells, which have retained the ability of alveolar epithelial type II cells to synthesize the major component of pulmonary surfactant, disaturated phosphatidylcholine. Stimulation of phosphatidylcholine secretion by calcium ionophore or phorbol ester augmented the susceptibility of these cells to Ad. Both Ad infection and recombinant-Ad-...

  12. Calmodulin activation by calcium transients in the postsynaptic density of dendritic spines.

    Directory of Open Access Journals (Sweden)

    Daniel X Keller

    Full Text Available The entry of calcium into dendritic spines can trigger a sequence of biochemical reactions that begins with the activation of calmodulin (CaM and ends with long-term changes to synaptic strengths. The degree of activation of CaM can depend on highly local elevations in the concentration of calcium and the duration of transient increases in calcium concentration. Accurate measurement of these local changes in calcium is difficult because the spaces are so small and the numbers of molecules are so low. We have therefore developed a Monte Carlo model of intracellular calcium dynamics within the spine that included calcium binding proteins, calcium transporters and ion channels activated by voltage and glutamate binding. The model reproduced optical recordings using calcium indicator dyes and showed that without the dye the free intracellular calcium concentration transient was much higher than predicted from the fluorescent signal. Excitatory postsynaptic potentials induced large, long-lasting calcium gradients across the postsynaptic density, which activated CaM. When glutamate was released at the synapse 10 ms before an action potential occurred, simulating activity patterns that strengthen hippocampal synapses, the calcium gradient and activation of CaM in the postsynaptic density were much greater than when the order was reversed, a condition that decreases synaptic strengths, suggesting a possible mechanism underlying the induction of long-term changes in synaptic strength. The spatial and temporal mechanisms for selectivity in CaM activation demonstrated here could be used in other signaling pathways.

  13. Study of High Capacitance Ratios CPW MEMS Shunt Switches

    Institute of Scientific and Technical Information of China (English)

    Jianhai Sun; Dafu Cui

    2006-01-01

    This paper describes a fixed-fixed beam ohmic switch in series with a fixed capacitor as a replacement for a capacitive switch. In this switch, a metal plate deposited on the dielectric ensures perfectly contact with the dielectric layer in the down state. The area size of the metal plate directly influences the capacitance ratio of the switch, as the area size of the metal cap decreases, the capacitance ratio dramatically rises up. The down/up capacitance ratio can exceed 800 times over the conventional designs using the same materials and the equal size. Measurement results show that high capacitance ratio of the switches has a large effect on the isolation, and can actually improve the performance of the switches.

  14. Electrostatic capacitance and Faraday cage behavior of carbon nanotube forests

    Energy Technology Data Exchange (ETDEWEB)

    Ya' akobovitz, A. [Mechanosynthesis Group, Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Department of Mechanical Engineering, Faculty of Engineering Sciences, Ben-Gurion University, Beer-Sheva (Israel); Bedewy, M. [Mechanosynthesis Group, Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Hart, A. J. [Mechanosynthesis Group, Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Department of Mechanical Engineering and Laboratory for Manufacturing and Productivity, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-02-02

    Understanding of the electrostatic properties of carbon nanotube (CNT) forests is essential to enable their integration in microelectronic and micromechanical devices. In this study, we sought to understand how the hierarchical geometry and morphology of CNT forests determines their capacitance. First, we find that at small gaps, solid micropillars have greater capacitance, yet at larger gaps the capacitance of the CNT forests is greater. The surface area of the CNT forest accessible to the electrostatic field was extracted by analysis of the measured capacitance, and, by relating the capacitance to the average density of CNTs in the forest, we find that the penetration depth of the electrostatic field is on the order of several microns. Therefore, CNT forests can behave as a miniature Faraday cage. The unique electrostatic properties of CNT forests could therefore enable their use as long-range proximity sensors and as shielding elements for miniature electronic devices.

  15. Nonlinear Dynamics of Capacitive Charging and Desalination by Porous Electrodes

    CERN Document Server

    Biesheuvel, P M

    2009-01-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by super-capacitors, water desalination and purification by capacitive deionization (or desalination), and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory in the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes wi...

  16. Electrostatic capacitance and Faraday cage behavior of carbon nanotube forests

    International Nuclear Information System (INIS)

    Understanding of the electrostatic properties of carbon nanotube (CNT) forests is essential to enable their integration in microelectronic and micromechanical devices. In this study, we sought to understand how the hierarchical geometry and morphology of CNT forests determines their capacitance. First, we find that at small gaps, solid micropillars have greater capacitance, yet at larger gaps the capacitance of the CNT forests is greater. The surface area of the CNT forest accessible to the electrostatic field was extracted by analysis of the measured capacitance, and, by relating the capacitance to the average density of CNTs in the forest, we find that the penetration depth of the electrostatic field is on the order of several microns. Therefore, CNT forests can behave as a miniature Faraday cage. The unique electrostatic properties of CNT forests could therefore enable their use as long-range proximity sensors and as shielding elements for miniature electronic devices

  17. Study of CMOS integrated signal processing circuit in capacitive sensors

    Institute of Scientific and Technical Information of China (English)

    CAO Yi-jiang; YU Xiang; WANG Lei

    2007-01-01

    A CMOS integrated signal processing circuit based on capacitance resonance principle whose structure is simple in capacitive sensors is designed. The waveform of output voltage is improved by choosing bootstrap reference current mirror with initiate circuit, CMOS analogy switch and positive feedback of double-stage inverter in the circuit. Output voltage of this circuit is a symmetric square wave signal. The variation of sensitive capacitance, which is part of the capacitive sensors, can be denoted by the change of output voltage's frequency. The whole circuit is designed with 1.5 μm P-well CMOS process and simulated by PSpice software.Output frequency varies from 261.05 kHz to 47.93 kHz if capacitance varies in the range of 1PF~15PF. And the variation of frequency can be easily detected using counter or SCU.

  18. Calcium in plant cells

    Directory of Open Access Journals (Sweden)

    V. V. Schwartau

    2014-04-01

    Full Text Available The paper gives the review on the role of calcium in many physiological processes of plant organisms, including growth and development, protection from pathogenic influences, response to changing environmental factors, and many other aspects of plant physiology. Initial intake of calcium ions is carried out by Ca2+-channels of plasma membrane and they are further transported by the xylem owing to auxins’ attractive ability. The level of intake and selectivity of calcium transport to ove-ground parts of the plant is controlled by a symplast. Ca2+enters to the cytoplasm of endoderm cells through calcium channels on the cortical side of Kaspary bands, and is redistributed inside the stele by the symplast, with the use of Ca2+-АТPases and Ca2+/Н+-antiports. Owing to regulated expression and activity of these calcium transporters, calclum can be selectively delivered to the xylem. Important role in supporting calcium homeostasis is given to the vacuole which is the largest depo of calcium. Regulated quantity of calcium movement through the tonoplast is provided by a number of potential-, ligand-gated active transporters and channels, like Ca2+-ATPase and Ca2+/H+ exchanger. They are actively involved in the inactivation of the calcium signal by pumping Ca2+ to the depo of cells. Calcium ATPases are high affinity pumps that efficiently transfer calcium ions against the concentration gradient in their presence in the solution in nanomolar concentrations. Calcium exchangers are low affinity, high capacity Ca2+ transporters that are effectively transporting calcium after raising its concentration in the cell cytosol through the use of protons gradients. Maintaining constant concentration and participation in the response to stimuli of different types also involves EPR, plastids, mitochondria, and cell wall. Calcium binding proteins contain several conserved sequences that provide sensitivity to changes in the concentration of Ca2+ and when you

  19. Calcium D-saccharate

    DEFF Research Database (Denmark)

    Garcia, André Castilho; Hedegaard, Martina Vavrusova; Skibsted, Leif Horsfelt

    2016-01-01

    Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc......° = -34 ± 6 kJ mol-1, and ΔSassoc° = -55 ± 9 J mol-1 K-1, were determined electrochemically. Calcium d-saccharate is sparingly soluble, with a solubility product, Ksp, of (6.17 ± 0.32) × 10-7 at 25 °C, only moderately increasing with the temperature: ΔHsol° = 48 ± 2 kJ mol-1, and ΔSassoc° = 42 ± 7 J mol-1...... K-1. Equilibria in supersaturated solutions of calcium d-saccharate seem only to adjust slowly, as seen from calcium activity measurements in calcium d-saccharate solutions made supersaturated by cooling. Solutions formed by isothermal dissolution of calcium d-gluconate in aqueous potassium d...

  20. Fund allocation using capacitated vehicle routing problem

    Science.gov (United States)

    Mamat, Nur Jumaadzan Zaleha; Jaaman, Saiful Hafizah; Ahmad, Rokiah Rozita; Darus, Maslina

    2014-09-01

    In investment fund allocation, it is unwise for an investor to distribute his fund into several assets simultaneously due to economic reasons. One solution is to allocate the fund into a particular asset at a time in a sequence that will either maximize returns or minimize risks depending on the investor's objective. The vehicle routing problem (VRP) provides an avenue to this issue. VRP answers the question on how to efficiently use the available fleet of vehicles to meet a given service demand, subjected to a set of operational requirements. This paper proposes an idea of using capacitated vehicle routing problem (CVRP) to optimize investment fund allocation by employing data of selected stocks in the FTSE Bursa Malaysia. Results suggest that CRVP can be applied to solve the issue of investment fund allocation and increase the investor's profit.

  1. Further capacitive imaging experiments using modified probes

    Science.gov (United States)

    Yin, Xiaokang; Li, Zhen; Yan, An; Li, Wei; Chen, Guoming; Hutchins, David A.

    2016-02-01

    In recent years, capacitive imaging (CI) is growing in popularity within the NDE communities, as it has the potential to test materials and structures for defects that are not easily tested by other techniques. In previous work, The CI technique has been successfully used on a various types of materials, including concrete, glass/carbon fibre composite, steel, etc. In such CI experiments, the probes are normally with symmetric or concentric electrodes etched onto PCBs. In addition to these conventional coplanar PCB probes, modified geometries can be made and they can lead to different applications. A brief overview of these modified probes, including high resolution surface imaging probe, combined CI/eddy current probe, and CI probe using an oscilloscope probe as the sensing electrode, is presented in this work. The potential applications brought by these probes are also discussed.

  2. Phase discriminating capacitive array sensor system

    Science.gov (United States)

    Vranish, John M. (Inventor); Rahim, Wadi (Inventor)

    1993-01-01

    A phase discriminating capacitive sensor array system which provides multiple sensor elements which are maintained at a phase and amplitude based on a frequency reference provided by a single frequency stabilized oscillator. Sensor signals provided by the multiple sensor elements are controlled by multiple phase control units, which correspond to the multiple sensor elements, to adjust the sensor signals from the multiple sensor elements based on the frequency reference. The adjustment made to the sensor signals is indicated by output signals which indicate the proximity of the object. The output signals may also indicate the closing speed of the object based on the rate of change of the adjustment made, and the edges of the object based on a sudden decrease in the adjustment made.

  3. Capacitance multiplier and filter synthesizing network

    Science.gov (United States)

    Kline, A. J. (Inventor)

    1974-01-01

    A circuit using a differential amplifier multiplies the capacitance of a discrete interating capacitor by (r sub 1 + R sub 2)/R sub 2, where R sub 1 and R sub 2 are values of discrete resistor coupling an input signal e sub 1 of the amplifier inputs. The output e sub 0 of the amplifier is fed back and added to the signal coupled by the resistor R sub 2 to the amplifier through a resistor of value R sub 1. A discrete resistor R sub x may be connected in series for a lag filter, and a discrete resistor may be connected in series with the capacitor for a lead-lag filter. Voltage dividing resistors R sub a and R sub b may be included in the feedback circuit of the amplifier output e sub o to independently adjust the circuit gain e sub i/e sub o.

  4. A capacitive bioelectrode for recording electrophysiological signals

    International Nuclear Information System (INIS)

    In this paper we describe a gel-free sensor with on-board electrode design, which capacitive couples to the skin to detect the electrical activity in the body. The integrated sensor is manufactured on a standard printed circuit board within 2.2 cm diameter enclosure that can operate through fabric or other insulation. The electrode includes amplification (60db gain) and passive band pass filtering (0.5 to 100 Hz). Active shielding surrounding the sensor plate is used to reduce noise pickup. The input referred noise, measured over the electrode bandwidth is 4 μV rms at 0.2 mm sensor distance, and 16 μV rms at 1.2 mm distance trough two cotton cloths. The bioelectrodes were coupled to the scalp trough hair for EEG signals (with 80 db gain), and coupled to the chest through clothing for ECG signals. The recorded signals show well performance of the designed bielectrode. (Author)

  5. [Wireless ECG measurement system with capacitive coupling].

    Science.gov (United States)

    Aleksandrowicz, Adrian; Walter, Marian; Leonhardt, Steffen

    2007-04-01

    This paper describes a measurement system that captures an electrocardiogram (ECG) using capacitively coupled electrodes. The measurement system was integrated into an off-the-shelf office chair (so-called "Aachen SmartChair"). Whereas for classical ECG measurement adhesive is used to attach conductively coupled electrodes to bare skin, the system presented allows ECG measurement through clothing without direct skin contact. Furthermore, a ZigBee communication module was integrated to allow wireless transmission of ECG data to a PC or an ICU patient monitor. For system validation, classical ECG using conductive electrodes was obtained simultaneously. First measurement results, including variations of cloth thickness and material, are presented and some of the system-specific problems of this approach are discussed.

  6. MOS Capacitance-Voltage Characteristics Ⅲ.Trapping Capacitance from 2-Charge-State Impurities

    Institute of Scientific and Technical Information of China (English)

    Jie Binbin; Sah Chihtang

    2011-01-01

    Low-frequency and high-frequency capacitance-voltage curves of Metal-Oxide-Semiconductor Capacitors are presented to illustrate giant electron and hole trapping capacitances at many simultaneously present two-charge-state and one-trapped-carrier,or one-energy-level impurity species.Models described include a donor electron trap and an acceptor hole trap,both donors,both acceptors,both shallow energy levels,both deep,one shallow and one deep,and the identical donor and acceptor.Device and material parameters are selected to simulate chemically and physically realizable capacitors for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.

  7. An integrated interface circuit with a capacitance-to-voltage converter as front-end for grounded capacitive sensors

    NARCIS (Netherlands)

    Heidary, A.; Meijer, G.C.M.

    2009-01-01

    This paper presents the analysis and design of an integrated interface for grounded capacitive sensors. To reduce the effects of parasitic cable capacitances, a feedforward technique has been applied. In combination with the use of a special front-end amplifier this yields high immunity for a parasi

  8. The hysteresis-free negative capacitance field effect transistors using non-linear poly capacitance

    Science.gov (United States)

    Fan, S.-T.; Yan, J.-Y.; Lai, D.-C.; Liu, C. W.

    2016-08-01

    A gate structure design for negative capacitance field effect transistors (NCFETs) is proposed. The hysteresis loop in current-voltage performances is eliminated by the nonlinear C-V dependence of polysilicon in the gate dielectrics. Design considerations and optimizations to achieve the low SS and hysteresis-free transfer were elaborated. The effects of gate-to-source/drain overlap, channel length scaling, interface trap states and temperature impact on SS are also investigated.

  9. Matrix Completion from Noisy Entries

    CERN Document Server

    Keshavan, Raghunandan H; Oh, Sewoong

    2009-01-01

    Given a matrix M of low-rank, we consider the problem of reconstructing it from noisy observations of a small, random subset of its entries. The problem arises in a variety of applications, from collaborative filtering (the `Netflix problem') to structure-from-motion and positioning. We study a low complexity algorithm introduced by Keshavan et al.(2009), based on a combination of spectral techniques and manifold optimization, that we call here OptSpace. We prove performance guarantees that are order-optimal in a number of circumstances.

  10. Transient exposure to calcium ionophore enables in vitro fertilization in sterile mouse models

    Science.gov (United States)

    Navarrete, Felipe A.; Alvau, Antonio; Lee, Hoi Chang; Levin, Lonny R.; Buck, Jochen; Leon, Patricia Martin-De; Santi, Celia M.; Krapf, Dario; Mager, Jesse; Fissore, Rafael A.; Salicioni, Ana M.; Darszon, Alberto; Visconti, Pablo E.

    2016-01-01

    Mammalian sperm acquire fertilizing capacity in the female tract in a process called capacitation. At the molecular level, capacitation requires protein kinase A activation, changes in membrane potential and an increase in intracellular calcium. Inhibition of these pathways results in loss of fertilizing ability in vivo and in vitro. We demonstrated that transient incubation of mouse sperm with Ca2+ ionophore accelerated capacitation and rescued fertilizing capacity in sperm with inactivated PKA function. We now show that a pulse of Ca2+ ionophore induces fertilizing capacity in sperm from infertile CatSper1 (Ca2+ channel), Adcy10 (soluble adenylyl cyclase) and Slo3 (K+ channel) KO mice. In contrast, sperm from infertile mice lacking the Ca2+ efflux pump PMACA4 were not rescued. These results indicate that a transient increase in intracellular Ca2+ can overcome genetic infertility in mice and suggest this approach may prove adaptable to rescue sperm function in certain cases of human male infertility. PMID:27627854

  11. Transient exposure to calcium ionophore enables in vitro fertilization in sterile mouse models.

    Science.gov (United States)

    Navarrete, Felipe A; Alvau, Antonio; Lee, Hoi Chang; Levin, Lonny R; Buck, Jochen; Leon, Patricia Martin-De; Santi, Celia M; Krapf, Dario; Mager, Jesse; Fissore, Rafael A; Salicioni, Ana M; Darszon, Alberto; Visconti, Pablo E

    2016-01-01

    Mammalian sperm acquire fertilizing capacity in the female tract in a process called capacitation. At the molecular level, capacitation requires protein kinase A activation, changes in membrane potential and an increase in intracellular calcium. Inhibition of these pathways results in loss of fertilizing ability in vivo and in vitro. We demonstrated that transient incubation of mouse sperm with Ca(2+) ionophore accelerated capacitation and rescued fertilizing capacity in sperm with inactivated PKA function. We now show that a pulse of Ca(2+) ionophore induces fertilizing capacity in sperm from infertile CatSper1 (Ca(2+) channel), Adcy10 (soluble adenylyl cyclase) and Slo3 (K(+) channel) KO mice. In contrast, sperm from infertile mice lacking the Ca(2+) efflux pump PMACA4 were not rescued. These results indicate that a transient increase in intracellular Ca(2+) can overcome genetic infertility in mice and suggest this approach may prove adaptable to rescue sperm function in certain cases of human male infertility. PMID:27627854

  12. Characterization of electrical and mechanical activities of rabbit uterus associated with the presence of capacitated and non-capacitated spermatozoa

    Directory of Open Access Journals (Sweden)

    J.F. Lazcano-Reyes

    2013-12-01

    Full Text Available To investigate the effects capacitated spermatozoa may exert upon motility of the rabbit uterus, both contractility and electrical activity (frequency and intensity were measured in 3 distinctive uterine segments of anaesthetized does: horn (UH, uterotubal junction (UTJ and tube (UT after 1 natural mating, 2 infusion of either seminal plasma or PBS, 3 infusion of either capacitated or non-capacitated spermatozoa. Basal values were: 17.1, 15.7, 16.4 g (contractility, P>0.05; 3.5, 3.5, 3.4 Hz (frequency, P>0.05; 0.49, 0.50, 0.57 μV (intensity, P>0.05 for UH, UTJ, UT, respectively. Seminal plasma caused an increase (P<0.05 in the UH contractility: 26.3 vs. 11.7 (natural mating and 17.0 g (PBS; it also caused a decrease (P<0.05 in electrical intensity at the UTJ: 0.24 vs. 0.67 (natural mating and 0.58 μV (PBS. The presence of either capacitated or non-capacitated spermatozoa caused no changes in contractility and electrical frequency in any of the uterine segments. However, there was a change in electrical intensity at UTJ (0.37 vs. 0.57 μV for non-capacitated and capacitated spermatozoa, respectively; P<0.05. There were also differences between segments by treatment: UTJ (0.37 vs. UT (0.59 μV for non-capacitated; UH (0.46 vs. UT (0.71 μV for capacitated spermatozoa (P<0.05. In conclusion, use of this experimental model showed that uterine electrical activity was slightly modified by the presence of capacitated spermatozoa.

  13. HYPERTHERMIA, INTRACELLULAR FREE CALCIUM AND CALCIUM IONOPHORES

    NARCIS (Netherlands)

    STEGE, GJJ; WIERENGA, PK; KAMPINGA, HH; KONINGS, AWT

    1993-01-01

    It is shown that heat-induced increase of intracellular calcium does not correlate with hyperthermic cell killing. Six different cell lines were investigated; in four (EAT, HeLa S3, L5178Y-R and L5178Y-S) heat treatments killing 90% of the cells did not affect the levels of intracellular free calciu

  14. Microdamage induced calcium efflux from bone matrix activates intracellular calcium signaling in osteoblasts via L-type and T-type voltage-gated calcium channels.

    Science.gov (United States)

    Jung, Hyungjin; Best, Makenzie; Akkus, Ozan

    2015-07-01

    Mechanisms by which bone microdamage triggers repair response are not completely understood. It has been shown that calcium efflux ([Ca(2+)]E) occurs from regions of bone undergoing microdamage. Such efflux has also been shown to trigger intracellular calcium signaling ([Ca(2+)]I) in MC3T3-E1 cells local to damaged regions. Voltage-gated calcium channels (VGCCs) are implicated in the entry of [Ca(2+)]E to the cytoplasm. We investigated the involvement of VGCC in the extracellular calcium induced intracellular calcium response (ECIICR). MC3T3-E1 cells were subjected to one dimensional calcium efflux from their basal aspect which results in an increase in [Ca(2+)]I. This increase was concomitant with membrane depolarization and it was significantly reduced in the presence of Bepridil, a non-selective VGCC inhibitor. To identify specific type(s) of VGCC in ECIICR, the cells were treated with selective inhibitors for different types of VGCC. Significant changes in the peak intensity and the number of [Ca(2+)]I oscillations were observed when L-type and T-type specific VGCC inhibitors (Verapamil and NNC55-0396, respectively) were used. So as to confirm the involvement of L- and T-type VGCC in the context of microdamage, cells were seeded on devitalized notched bone specimen, which were loaded to induce microdamage in the presence and absence of Verapamil and NNC55-0396. The results showed significant decrease in [Ca(2+)]I activity of cells in the microdamaged regions of bone when L- and T-type blockers were applied. This study demonstrated that extracellular calcium increase in association with damage depolarizes the cell membrane and the calcium ions enter the cell cytoplasm by L- and T-type VGCCs.

  15. Hydraulic Resistance and Capacitance in the Soil—Plant System

    Institute of Scientific and Technical Information of China (English)

    SHAOMING-AN; L.P.SIMMONDS

    1991-01-01

    In this paper,the hydraulic resistances and capacitances were evaluated.based on the development of non-linear model of water flow in the soil-plant system and the simulating experiment work.The results show that the mean hydraulic resistance in the soil-plant system is 6.79×109 MPa·S·m-3;the mean hydraulic capacitance in the system is 5.2×10-7m3·MPa-1.In the components of hydraulic capacitance in the system,the capacitance in soil (81.8×10-6m3·MPa-1)is the biggest and its variability with soil water potential is extremely strong,the capacitance in plant (5.3×10-7m3·MPa-1) is much smaller than that in soil,and the capacitance in shoots (15.5×10-7m3·MPa-1) is bigger than that in roots (8.4×10-7m3·MPa-1).An interesting result is that the capacitance in plant is almost equivalent to that in the soil-plant system.

  16. Filamin and phospholipase C-ε are required for calcium signaling in the Caenorhabditis elegans spermatheca.

    Directory of Open Access Journals (Sweden)

    Ismar Kovacevic

    2013-05-01

    Full Text Available The Caenorhabditis elegans spermatheca is a myoepithelial tube that stores sperm and undergoes cycles of stretching and constriction as oocytes enter, are fertilized, and exit into the uterus. FLN-1/filamin, a stretch-sensitive structural and signaling scaffold, and PLC-1/phospholipase C-ε, an enzyme that generates the second messenger IP3, are required for embryos to exit normally after fertilization. Using GCaMP, a genetically encoded calcium indicator, we show that entry of an oocyte into the spermatheca initiates a distinctive series of IP3-dependent calcium oscillations that propagate across the tissue via gap junctions and lead to constriction of the spermatheca. PLC-1 is required for the calcium release mechanism triggered by oocyte entry, and FLN-1 is required for timely initiation of the calcium oscillations. INX-12, a gap junction subunit, coordinates propagation of the calcium transients across the spermatheca. Gain-of-function mutations in ITR-1/IP3R, an IP3-dependent calcium channel, and loss-of-function mutations in LFE-2, a negative regulator of IP3 signaling, increase calcium release and suppress the exit defect in filamin-deficient animals. We further demonstrate that a regulatory cassette consisting of MEL-11/myosin phosphatase and NMY-1/non-muscle myosin is required for coordinated contraction of the spermatheca. In summary, this study answers long-standing questions concerning calcium signaling dynamics in the C. elegans spermatheca and suggests FLN-1 is needed in response to oocyte entry to trigger calcium release and coordinated contraction of the spermathecal tissue.

  17. The genetic background affects the vascular response in T-type calcium channels 3.2 deficient mice

    DEFF Research Database (Denmark)

    Svenningsen, Per; Hansen, Pernille B L

    2016-01-01

    -type channels are the dominant Ca(2+) entry pathway in vascular smooth muscle cells, however, T-type calcium channels are also expressed in the cardiovascular system where they play a functional role in the regulation of both contraction and vasodilation in (Chen et al. 2003; Hansen et al. 2001). This article......Voltage-gated calcium channels (Cav ) are important regulators of vascular tone and are attractive targets for pharmacological treatment of hypertension. The clinical used calcium blockers are often not selective for one channel but affect several types of calcium channels (Hansen 2015). L...

  18. Who Benefits from Store Brand Entry?

    OpenAIRE

    Koen Pauwels; Shuba Srinivasan

    2004-01-01

    Store brand entry has become a key issue in marketing as it may structurally change the performance of and the interactions among all market players. Based on their multivariate time-series analysis, the authors demonstrate permanent performance effects of store brand entry, typically benefiting the retailer, the consumers, and premium-brand manufacturers, while harming second-tier brand manufacturers. For the , they consistently find two of store brand entry: . This increase in unit margins ...

  19. Nanoporous activated carbon cloth for capacitive deionization of aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Han-Jun [Department of Materials Science, Hanseo University, Seosan, 352-820 (Korea, Republic of); Lee, Jong-Ho [Department of Chemistry, Hanseo University, Seosan, 352-820 (Korea, Republic of); Ahn, Hong-Joo [Korea Atomic Energy Research Institute, Daejeon, 305-600 (Korea, Republic of); Jeong, Yongsoo [Korea Institute of Machinery and Materials, Changwon, 641-010 (Korea, Republic of); Kim, Young-Jig [Department of Metallurgical Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Chi, Choong-Soo [School of Advanced Materials Engineering, Kookmin University, Seoul, 136-702 (Korea, Republic of)]. E-mail: cschi@kookmin.ac.kr

    2006-09-25

    Activated nanostructured-carbon cloths with a high ratio of surface area to volume are used as electrode for capacitive deionization. The electrochemical properties on capacitive deionization for NaCl solution have been investigated to improve efficiency of capacitive deionization properties from aqueous solution, employing chemical surface-modification by etching in alkaline and acidic solution. The removal efficiency of inorganic salts of activated carbon cloths by chemical modification significantly increased. Specially the carbon cloth surface modified in HNO{sub 3} showed an effect of improvement in the CDI efficiency due to not only ion adsorption by an electric double layer, but also electron transfer by Faradaic reaction.

  20. Bloch inductance in small-capacitance Josephson junctions.

    Science.gov (United States)

    Zorin, A B

    2006-04-28

    We show that the electrical impedance of a small-capacitance Josephson junction also includes, in addition to the capacitive term -i/(omega)CB, an inductive term i(omega)LB. Similar to the known Bloch capacitance CB(q), the Bloch inductance LB(q) also depends periodically on the quasicharge, q, and its maximum value achieved at q=e(mod 2e) always exceeds the value of the Josephson inductance of this junction LJ(phi) at fixed phi=0. The effect of the Bloch inductance on the dynamics of a single junction and a one-dimensional array is described.

  1. Flexible transparent iontronic film for interfacial capacitive pressure sensing.

    Science.gov (United States)

    Nie, Baoqing; Li, Ruya; Cao, Jennifer; Brandt, James D; Pan, Tingrui

    2015-10-21

    A flexible, transparent iontronic film is introduced as a thin-film capacitive sensing material for emerging wearable and health-monitoring applications. Utilizing the capacitive interface at the ionic-electronic contact, the iontronic film sensor offers a large unit-area capacitance (of 5.4 μF cm(-2) ) and an ultrahigh sensitivity (of 3.1 nF kPa(-1) ), which is a thousand times greater than that of traditional solid-state counterparts. PMID:26333011

  2. Correcting For Capacitance In Tests Of Solar Cells

    Science.gov (United States)

    Mueller, Robert L.

    1995-01-01

    Modified procedure for testing solar photovoltaic cells and modified software for processing test data provide corrections for effects of cell capacitance. Procedure and software needed because (a) some photovoltaic devices (for example, silicon solar cells with back-surface field region) store minority charge carriers in cell junction and thus exhibit significant capacitance, (b) capacitance affects current-vs.-voltage (I-V) measurements made when transient load connected to cell, and (c) transient load used in unmodified version of test procedure. Corrected I-V curve obtained in test of solar cell according to modified procedure approximates true cell voltage vs. cell current more closely.

  3. Electrochemical Capacitance DNA Sensing at Hairpin-Modified Au Electrodes

    OpenAIRE

    Joel Rivera-Gandía; Maria del Mar Maldonado; Yarimar De La Torre-Meléndez; Edwin O. Ortiz-Quiles; Vargas-Barbosa, Nella M.; Cabrera, Carlos R.

    2011-01-01

    An interfacial capacitance measurement electrochemical technique has been used for the sensing of self-assembled DNA hairpin probes (M. tuberculosis and B. anthracis) attached to Au electrodes. The double-layer capacitance (Cdl) was determined with electrochemical perturbations from 0.2 V to 0.5 V versus Ag/AgCl at a Au/M. tuberculosis DNA hairpin probe at surface coverage Au electrodes. The capacitance study was done at pH 7, which was necessary to maintain the M. tuberculosis and B. anthrac...

  4. Characterization of electrical and mechanical activities of rabbit uterus associated with the presence of capacitated and non-capacitated spermatozoa

    OpenAIRE

    J.F. Lazcano-Reyes; Montiel, J.L.; Medrano, A.

    2013-01-01

    To investigate the effects capacitated spermatozoa may exert upon motility of the rabbit uterus, both contractility and electrical activity (frequency and intensity) were measured in 3 distinctive uterine segments of anaesthetized does: horn (UH), uterotubal junction (UTJ) and tube (UT) after 1) natural mating, 2) infusion of either seminal plasma or PBS, 3) infusion of either capacitated or non-capacitated spermatozoa. Basal values were: 17.1, 15.7, 16.4 g (contractility, P>0.05); 3.5, 3.5, ...

  5. Thermodynamic cycle analysis for capacitive deionization.

    Science.gov (United States)

    Biesheuvel, P M

    2009-04-01

    Capacitive deionization (CDI) is an ion removal technology based on temporarily storing ions in the polarization layers of two oppositely positioned electrodes. Here we present a thermodynamic model for the minimum work required for ion separation in the fully reversible case by describing the ionic solution as an ideal gas of pointlike particles. The work input is fully utilized to decrease the entropy of the outflowing streams compared to that of the inflow. Based on the Gouy-Chapman-Stern (GCS) model for planar diffuse polarization layers-with and without including additional ion volume constraints in the diffuse part of the double layer-we analyze the electric work input during charging and the work output during discharging, for a reversible charging-discharging cycle. We present a graphical thermodynamic cycle analysis for the reversible net work input during one full cycle of batchwise operation of CDI based on the charge-voltage relations for different ionic strengths. For the GCS model, an analytical solution is derived for the charge efficiency Lambda, which is the number of salt molecules removed per electron transferred from one electrode to the other. Only in the high voltage limit and for an infinite Stern layer capacity does Lambda approach unity. PMID:19167009

  6. Energy recovery in membrane capacitive deionization.

    Science.gov (United States)

    Długołęcki, Piotr; van der Wal, Albert

    2013-05-01

    Membrane capacitive deionization (MCDI) is a water desalination technology based on applying a cell voltage between two oppositely placed porous carbon electrodes. In front of each electrode, an ion-exchange membrane is positioned, and between them, a spacer is situated, which transports the water to be desalinated. In this work, we demonstrate for the first time that up to 83% of the energy used for charging the electrodes during desalination can be recovered in the regeneration step. This can be achieved by charging and discharging the electrodes in a controlled manner by using constant current conditions. By implementing energy recovery as an integral part of the MCDI operation, the overall energy consumption can be as low as 0.26 (kW·h)/m(3) of produced water to reduce the salinity by 10 mM, which means that MCDI is more energy efficient for treatment of brackish water than reverse osmosis. Nevertheless, the measured energy consumption is much higher than the thermodynamically calculated values for desalinating the water, and therefore, a further improvement in thermodynamic efficiency will be needed in the future. PMID:23477563

  7. Complementary surface charge for enhanced capacitive deionization.

    Science.gov (United States)

    Gao, X; Porada, S; Omosebi, A; Liu, K-L; Biesheuvel, P M; Landon, J

    2016-04-01

    Commercially available activated carbon cloth electrodes are treated using nitric acid and ethylenediamine solutions, resulting in chemical surface charge enhanced carbon electrodes for capacitive deionization (CDI) applications. Surface charge enhanced electrodes are then configured in a CDI cell to examine their salt removal at a fixed charging voltage and both reduced and opposite polarity discharge voltages, and subsequently compared to the salt removal of untreated electrodes. Substantially improved salt removal due to chemical surface charge and the use of a discharge voltage of opposite sign to the charging voltage is clearly demonstrated in these CDI cycling tests, an observation which for the first time validates both enhanced CDI and extended-voltage CDI effects predicted by the Donnan model [Biesheuvel et al., Colloids Interf. Sci. Comm., 10.1016/j.colcom.2015.12.001 (2016)]. Our experimental and theoretical results demonstrate that the use of carbon electrodes with optimized chemical surface charge can extend the CDI working voltage window through discharge voltages of opposite sign to the charging voltage, which can significantly enhance the salt adsorption capacity of CDI electrodes. Thus, in addition to carbon pore size distribution, chemical surface charge in carbon micropores is considered foundational for salt removal in CDI cells. PMID:26878361

  8. Combinatorial Algorithms for Capacitated Network Design

    CERN Document Server

    Hajiaghayi, MohammadTaghi; Kortsarz, Guy; Nutov, Zeev

    2011-01-01

    We focus on designing combinatorial algorithms for the Capacitated Network Design problem (Cap-SNDP). The Cap-SNDP is the problem of satisfying connectivity requirements when edges have costs and hard capacities. We begin by showing that the Group Steiner tree problem (GST) is a special case of Cap-SNDP even when there is connectivity requirement between only one source-sink pair. This implies the first poly-logarithmic lower bound for the Cap-SNDP. We next provide combinatorial algorithms for several special cases of this problem. The Cap-SNDP is equivalent to its special case when every edge has either zero cost or infinite capacity. We consider a special case, called Connected Cap-SNDP, where all infinite-capacity edges in the solution are required to form a connected component containing the sinks. This problem is motivated by its similarity to the Connected Facility Location problem [G+01,SW04]. We solve this problem by reducing it to Submodular tree cover problem, which is a common generalization of Con...

  9. An uncooled capacitive sensor for IR detection

    Science.gov (United States)

    Siebke, Georg; Gerngroß, Kathrin; Holik, Peter; Schmitz, Sam; Rohloff, Markus; Tätzner, Simon; Steltenkamp, Siegfried

    2014-06-01

    The beetle Melanophila acuminata detects forest fires from distances as far as 80 miles away. To accomplish this, the beetle uses highly specific IR receptors with a diameter of approximately 15 μm. These receptors are mechanoreceptors that detect deformations induced by the absorption of radiation. Although the detection mechanism is understood in principle, it is still unclear how the beetle reaches such high sensitivity. In this work, we present the biomimetic approach of an uncooled IR sensor based on the beetle's receptors. This sensor is based on a fluid-filled pressure cell and operates at room temperature. Upon absorbing IR radiation, the fluid heats up and expands. The expanding fluid deflects one electrode of a plate capacitor. By measuring the change in capacitance, the volume increase and the absorbed energy can be inferred. To prevent the risk of damage at high energy absorption, a compensation mechanism is presented in this work. The mechanism prevents large but slow volume changes inside the pressure cell by a microfluidic connection of the pressure cell with a compensation chamber. The channel and the compensation chamber act as a microfluidic low-pass filter and do not affect the overall sensitivity above an appropriate cut-off frequency. Using MEMS technology, we are able to incorporate the complete system into a silicon chip with an area of a few mm2. Here, we show a proof-of-concept and first measurements of the sensor.

  10. Mechano-capacitive properties of polarized membranes.

    Science.gov (United States)

    Mosgaard, Lars D; Zecchi, Karis A; Heimburg, Thomas

    2015-10-28

    Biological membranes are capacitors that can be charged by applying a field across the membrane. The charges on the capacitor exert a force on the membrane that leads to electrostriction, i.e. a thinning of the membrane. Since the force is quadratic in voltage, negative and positive voltage have an identical influence on the physics of symmetric membranes. However, this is not the case for a membrane with an asymmetry leading to a permanent electric polarization. Positive and negative voltages of identical magnitude lead to different properties. Such an asymmetry can originate from a lipid composition that is different on the two monolayers of the membrane, or from membrane curvature. The latter effect is called 'flexoelectricity'. As a consequence of permanent polarization, the membrane capacitor is discharged at a voltage different from zero. This leads to interesting electrical phenomena such as outward or inward rectification of membrane permeability. Here, we introduce a generalized theoretical framework, that treats capacitance, polarization, flexoelectricity, piezoelectricity and thermoelectricity in the same language. We show applications to electrostriction, membrane permeability and piezoelectricity and thermoelectricity close to melting transitions, where such effects are especially pronounced. PMID:26324950

  11. Capacitance Probe Resonator for Multichannel Electrometer

    Science.gov (United States)

    Blaes, Brent R.; Schaefer, Rembrandt T> Glaser, Robert J.

    2012-01-01

    A multichannel electrometer voltmeter has been developed that employs a mechanical resonator with voltage-sensing capacitance-probe electrodes that enable high-impedance, high-voltage, radiation-hardened measurement of an Internal Electrostatic Discharge Monitor (IESDM) sensor. The IESDM is new sensor technology targeted for integration into a Space Environmental Monitor (SEM) subsystem used for the characterization and monitoring of deep dielectric charging on spacecraft. The resonator solution relies on a non-contact, voltage-sensing, sinusoidal-varying capacitor to achieve input impedances as high as 10 petaohms as determined by the resonator materials, geometries, cleanliness, and construction. The resonator is designed with one dominant mechanical degree of freedom, so it resonates as a simple harmonic oscillator and because of the linearity of the variable sense capacitor to displacement, generates a pure sinusoidal current signal for a fixed input voltage under measurement. This enables the use of an idealized phase-lock sensing scheme for optimal signal detection in the presence of noise.

  12. Design Considerations in Capacitively Coupled Plasmas

    Science.gov (United States)

    Song, Sang-Heon; Ventzek, Peter; Ranjan, Alok

    2015-11-01

    Microelectronics industry has driven transistor feature size scaling from 10-6 m to 10-9 m during the past 50 years, which is often referred to as Moore's law. It cannot be overstated that today's information technology would not have been so successful without plasma material processing. One of the major plasma sources for the microelectronics fabrication is capacitively coupled plasmas (CCPs). The CCP reactor has been intensively studied and developed for the deposition and etching of different films on the silicon wafer. As the feature size gets to around 10 nm, the requirement for the process uniformity is less than 1-2 nm across the wafer (300 mm). In order to achieve the desired uniformity, the hardware design should be as precise as possible before the fine tuning of process condition is applied to make it even better. In doing this procedure, the computer simulation can save a significant amount of resources such as time and money which are critical in the semiconductor business. In this presentation, we compare plasma properties using a 2-dimensional plasma hydrodynamics model for different kinds of design factors that can affect the plasma uniformity. The parameters studied in this presentation include chamber accessing port, pumping port, focus ring around wafer substrate, and the geometry of electrodes of CCP.

  13. Locating Depots for Capacitated Vehicle Routing

    CERN Document Server

    Goertz, Inge Li

    2011-01-01

    We study a location-routing problem in the context of capacitated vehicle routing. The input is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so that all demands are satisfied and the total cost is minimized. Our main result is a constant-factor approximation algorithm for this problem. To achieve this result, we reduce to the k-median-forest problem, which generalizes both k-median and minimum spanning tree, and which might be of independent interest. We give a (3+c)-approximation algorithm for k-median-forest, which leads to a (12+c)-approximation algorithm for the above location-routing problem, for any constant c>0. The algorithm for k-median-forest is just t-swap local search, and we prove that it has locality gap 3+2/t; this generalizes the corresponding result known for k-median. Finally we consider the "non-uniform" k-median-forest problem which has different cost ...

  14. Instabilities in a capacitively coupled oxygen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Küllig, C., E-mail: kuellig@physik.uni-greifswald.de; Wegner, Th., E-mail: physics@thwegner.com; Meichsner, J., E-mail: meichsner@physik.uni-greifswald.de [Institute of Physics, University of Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany)

    2015-04-15

    Periodic fluctuations in the frequency range from 0.3 to 3 kHz were experimentally investigated in capacitively coupled radio frequency (13.56 MHz) oxygen plasma. The Gaussian beam microwave interferometry directly provides the line integrated electron density fluctuations. A system of two Langmuir probes measured the floating potential spatially (axial, radial) and temporally resolved. Hence, the floating potential fluctuation development is mapped within the discharge volume and provides a kind of discharge breathing and no wave propagation. Finally, it was measured the optical emission pattern of atomic oxygen during the fluctuation as well as the RF phase resolved optical emission intensity at selected phase position of the fluctuation by an intensified charge-coupled device camera. The deduced excitation rate pattern reveals the RF sheath dynamics and electron heating mechanisms, which is changing between low and high electronegativity during a fluctuation cycle. A perturbation calculation was taken into account using a global model with 15 elementary collision processes in the balance equations for the charged plasma species (O{sub 2}{sup +}, e, O{sup −}, O{sub 2}{sup −}) and a harmonic perturbation. The calculated frequencies agree with the experimentally observed frequencies. Whereby, the electron attachment/detachment processes are important for the generation of this instability.

  15. Locating Depots for Capacitated Vehicle Routing

    DEFF Research Database (Denmark)

    Gørtz, Inge Li; Nagarajan, Viswanath

    2011-01-01

    We study a location-routing problem in the context of capacitated vehicle routing. The input to k-LocVRP is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so...... median forest, which leads to a (12+E)-approximation algorithm for k-LocVRP, for any constant E > 0. The algorithm for k median forest is t-swap local search, and we prove that it has locality gap 3 + 2 t ; this generalizes the corresponding result for k median [3]. Finally we consider the k median...... forest problem when there is a different (unrelated) cost function c for the MST part, i.e. the objective is Eu∈V d(u, S) + c(MST(V/S) ). We show that the locality gap for this problem is unbounded even under multi-swaps, which contrasts with the c = d case. Nevertheless, we obtain a constant...

  16. Spatial resolution in electrical capacitance tomography

    CERN Document Server

    Lucas, Jérôme; Oussar, Yacine; Holé, Stéphane

    2015-01-01

    Electrical Capacitance Tomography (ECT) is an imaging technique providing the distribution of permittivity in a medium by the mean of electrodes. As for any imaging systems, the reachable spatial resolution is a key parameter. In this paper the spatial resolution of ECT sensors is analyzed in terms of the accuracy of an object position and of the ability to distinguish between two close objects. Cylindrical geometry sensors are particularly studied and the example of a square geometry sensor is used to show how to study any other geometries. In cylindrical geometries, it is shown that a 50% gap between electrodes is a good compromise and that increasing the number of electrodes improves the spatial resolution near the electrodes but decreases the spatial resolution in the center. The best spatial resolution at the center of the sensor is obtained with 3 or 4 electrodes. In the square geometry studied, it is shown that a better distribution of the spatial resolution is obtained when there are electrodes in the...

  17. Enhancement of the carbon electrode capacitance by brominated hydroquinones

    Science.gov (United States)

    Gastol, Dominika; Walkowiak, Jedrzej; Fic, Krzysztof; Frackowiak, Elzbieta

    2016-09-01

    This paper presents supercapacitors utilizing new redox-active electrolytes with bromine species. Two sources of Br specimen were investigated, i.e. dibromodihydroxybenzene dissolved in KOH and potassium bromide dissolved in KOH with hydroxybenzene additive. KOH-activated carbon, exhibiting a well-developed porosity, was incorporated as an electrode material. The tested systems revealed a capacitance enhancement explained by Br- and partial BrO3- redox activity. The optimisation of the electrolyte concentration resulted in a capacitance value of 314 F g-1 achieved at 1.1 V voltage range. Good cyclability performance (11% capacitance loss) combined with a high capacitance value (244 F g-1) were obtained for the system operating in 0.2 mol L- 1 C6H4Br2O2 in 2 mol L-1 KOH electrolytic solution.

  18. Fringe Capacitance of a Parallel-Plate Capacitor.

    Science.gov (United States)

    Hale, D. P.

    1978-01-01

    Describes an experiment designed to measure the forces between charged parallel plates, and determines the relationship among the effective electrode area, the measured capacitance values, and the electrode spacing of a parallel plate capacitor. (GA)

  19. Capacitance-Power-Hysteresis Trilemma in Nanoporous Supercapacitors

    Science.gov (United States)

    Lee, Alpha A.; Vella, Dominic; Goriely, Alain; Kondrat, Svyatoslav

    2016-04-01

    Nanoporous supercapacitors are an important player in the field of energy storage that fill the gap between dielectric capacitors and batteries. The key challenge in the development of supercapacitors is the perceived trade-off between capacitance and power delivery. Current efforts to boost the capacitance of nanoporous supercapacitors focus on reducing the pore size so that they can only accommodate a single layer of ions. However, this tight packing compromises the charging dynamics and hence power density. We show via an analytical theory and Monte Carlo simulations that charging is sensitively dependent on the affinity of ions to the pores, and that high capacitances can be obtained for ionophobic pores of widths significantly larger than the ion diameter. Our theory also predicts that charging can be hysteretic with a significant energy loss per cycle for intermediate ionophilicities. We use these observations to explore the parameter regimes in which a capacitance-power-hysteresis trilemma may be avoided.

  20. Segmented Capacitance Sensor with Partially Released Inactive Segments

    Directory of Open Access Journals (Sweden)

    Lev Jakub

    2015-09-01

    Full Text Available Material throughput measurement is important for many applications, for example yield maps creation or control of mass flow in stationary lines. Quite perspective can be the capacitive throughput method. Segmented capacitance sensor (SCS is discussed in this paper. SCS is a compromise between simple capacitive throughput sensors and electrical capacitance tomography sensors. The SCS variant with partially released inactive segments is presented. The mathematical model of SCS was created and verified by measurements. A good correspondence between measured and computed values was found and it can be stated that the proposed mathematical model was verified. During measurement the voltage values on the inactive segments were monitored as well. On the basis of the measurement there was found that these values are significantly influenced by material distribution.

  1. High Voltage Bi-directional Flyback Converter for Capacitive Actuator

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    This paper presents a high voltage DC-DC converter topology for bi-directional energy transfer between a low voltage DC source and a high voltage capacitive load. The topology is a bi-directional flyback converter with variable switching frequency control during the charge mode, and constant...... switching frequency control during the discharge mode. The converter is capable of charging the capacitive load from 24 V DC source to 2.5 kV, and discharges it to 0 V. The flyback converter has been analyzed in detail during both charge and discharge modes, by considering all the parasitic elements...... in the converter, including the most dominating parameters of the high voltage transformer viz., self-capacitance and leakage inductance. The specific capacitive load for this converter is a dielectric electro active polymer (DEAP) actuator, which can be used as an effective replacement for conventional actuators...

  2. Design of Excitation Capacitance for Self-Excited Induction Generator

    Directory of Open Access Journals (Sweden)

    Swati Devabhaktuni

    2011-12-01

    Full Text Available This paper presents simple and accurate approach to compute the minimum value of capacitance required for initiating the voltage build-up in a three-phase selfexcited induction generator. Based on the steady-state equivalent circuit model different numerical methods for solving frequency are known from previous literature, which are of 6th order polynomial. In this paper the order of the polynomial is reduced to the 4thorder frequency with a new, simple and direct method is developed to find the capacitance requirement. Critical values of the impedance and speed, below which the machine fails to self excite irrespective of the capacitance used, are found to exist. Closed form solutions for capacitance are derived for no-load and RL loads. Experimental results obtained on a 3.5kW induction machine confirm the feasibility and accuracy of the proposed method.

  3. A Review of High Voltage Drive Amplifiers for Capacitive Actuators

    DEFF Research Database (Denmark)

    Huang, Lina; Zhang, Zhe; Andersen, Michael A. E.

    2012-01-01

    This paper gives an overview of the high voltage amplifiers, which are used to drive capacitive actuators. The amplifiers for both piezoelectric and DEAP (dielectric electroactive polymer) actuator are discussed. The suitable topologies for driving capacitive actuators are illustrated in detail, ......, including linear as well as switched mode amplifiers. In the past much attention has been paid on the driver for piezoelectric actuator. As DEAP is a type of new material, there is not much literature reference for it.......This paper gives an overview of the high voltage amplifiers, which are used to drive capacitive actuators. The amplifiers for both piezoelectric and DEAP (dielectric electroactive polymer) actuator are discussed. The suitable topologies for driving capacitive actuators are illustrated in detail...

  4. Composite metal-oxide device has voltage sensitive capacitance

    Science.gov (United States)

    Mattauch, R. J.; Viola, T. J., Jr.

    1970-01-01

    Device with step function variation of the capacitance is useful for voltage-controlled oscillator circuits and as a voltage-sensitive switch. Simplicity of construction makes the device suitable for large-scale integration, microelectronic circuits.

  5. Structure and Capacitance of Electrical Double Layers inside Micropores

    Science.gov (United States)

    Feng, Guang; Qiao, Rui; Huang, Jingsong; Sumpter, Bobby G.; Meunier, Vincent

    2010-03-01

    Recent experiments indicate that the specific capacitance of micropores (diameter less than 2nm) increases anomalously as the pore size decreases^[1]. To understand the physical origin of this discovery, we performed a series of molecular dynamics simulations to study the electrical double layers (EDLs) in micropores with different shapes (tube vs slit) and pore sizes (0.668nm - 3.342nm). Several different aqueous electrolytes (K^+, Na^+, Cl^-, and F^- in water) were used in these micropores. We quantified the structure of EDLs inside the pores, and computed the capacitance of EDLs. The scaling of capacitance shows a qualitative agreement with the experimental observations. We attribute the anomalous enhancement of capacitance in micropores to the short-range ionelectrode and ionsolvent interactions.[1] J. Chmiola, G. Yushin, Y. Gogotsi, C. Portet, P. Simon, and P.L. Taberna, Science 2006, 313, 1760.

  6. Integration of Capacitive Micromachined Ultrasound Transducers to Microfluidic Devices

    KAUST Repository

    Viržonis, Darius

    2013-10-22

    The design and manufacturing flexibility of capacitive micromachined ultrasound transducers (CMUT) makes them attractive option for integration with microfluidic devices both for sensing and fluid manipulation. CMUT concept is introduced here by presentin

  7. Voidage measurement based on genetic algorithm and electrical capacitance tomography

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-wei; WANG Bao-liang; HUANG Zhi-yao; LI Hai-qing

    2005-01-01

    A new voidage measurement method based on electrical capacitance tomography (ECT) technique, Genetic Algorithm (GA) and Partial Least Square (PLS) method was proposed. The voidage measurement model, linear capacitance combination, was developed to measure on-line voidage. GA and PLS method were used to determine the coefficients of the voidage measurement model. GA was used to explore the optimal capacitance combination which gave significant contribution to the voidage measurement. PLS method was applied to determine the weight coefficient of the contribution of each capacitance to the voidage measurement. Flow pattern identification result was introduced to improve the voidage measurement accuracy. Experimental results showed that the proposed voidage measurement method is effective and that the measurement accuracy is satisfactory.

  8. Calcium binding by dietary fibre

    International Nuclear Information System (INIS)

    Dietary fibre from plants low in phytate bound calcium in proportion to its uronic-acid content. This binding by the non-cellulosic fraction of fibre reduces the availability of calcium for small-intestinal absorption, but the colonic microbial digestion of uronic acids liberates the calcium. Thus the ability to maintain calcium balance on high-fibre diets may depend on the adaptive capacity on the colon for calcium. (author)

  9. Acidosis and Urinary Calcium Excretion

    DEFF Research Database (Denmark)

    Alexander, R Todd; Cordat, Emmanuelle; Chambrey, Régine;

    2016-01-01

    Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone...... and inhibition of calcium transport processes within the renal tubule. The mechanisms whereby acid alters the integrity and stability of bone have been examined extensively in the published literature. Here, after briefly reviewing this literature, we consider the effects of acid on calcium transport...

  10. Current Progress of Capacitive Deionization for Removal of Pollutant Ions

    Science.gov (United States)

    Gaikwad, Mahendra S.; Balomajumder, Chandrajit

    2016-08-01

    A mini review of a recently developing water purification technology capacitive deionization (CDI) applied for removal of pollutant ions is provided. The current progress of CDI for removal of different pollutant ions such as arsenic, fluoride, boron, phosphate, lithium, copper, cadmium, ferric, and nitrate ions is presented. This paper aims at motivating new research opportunities in capacitive deionization technology for removal of pollutant ions from polluted water.

  11. Capacitive Sensors for Measuring Masses of Cryogenic Fluids

    Science.gov (United States)

    Nurge, Mark; Youngquist, Robert

    2003-01-01

    An effort is under way to develop capacitive sensors for measuring the masses of cryogenic fluids in tanks. These sensors are intended to function in both microgravitational and normal gravitational settings, and should not be confused with level sensors, including capacitive ones. A sensor of this type is conceptually simple in the sense that (1) it includes only one capacitor and (2) if properly designed, its single capacitance reading should be readily convertible to a close approximation of the mass of the cryogenic fluid in the tank. Consider a pair of electrically insulated electrodes used as a simple capacitive sensor. In general, the capacitance is proportional to the permittivity of the dielectric medium (in this case, a cryogenic fluid) between the electrodes. The success of design and operation of a sensor of the present type depends on the accuracy of the assumption that to a close approximation, the permittivity of the cryogenic fluid varies linearly with the density of the fluid. Data on liquid nitrogen, liquid oxygen, and liquid hydrogen, reported by the National Institute of Standards and Technology, indicate that the permittivities and densities of these fluids are, indeed, linearly related to within a few tenths of a percent over the pressure and temperature regions of interest. Hence, ignoring geometric effects for the moment, the capacitance between two electrodes immersed in the fluid should vary linearly with the density, and, hence, with the mass of the fluid. Of course, it is necessary to take account of the tank geometry. Because most cryogenic tanks do not have uniform cross sections, the readings of level sensors, including capacitive ones, are not linearly correlated with the masses of fluids in the tanks. In a sensor of the present type, the capacitor electrodes are shaped so that at a given height, the capacitance per unit height is approximately proportional to the cross-sectional area of the tank in the horizontal plane at that

  12. Probing Quantum Capacitance in a 3D Topological Insulator

    Science.gov (United States)

    Kozlov, D. A.; Bauer, D.; Ziegler, J.; Fischer, R.; Savchenko, M. L.; Kvon, Z. D.; Mikhailov, N. N.; Dvoretsky, S. A.; Weiss, D.

    2016-04-01

    We measure the quantum capacitance and probe thus directly the electronic density of states of the high mobility, Dirac type two-dimensional electron system, which forms on the surface of strained HgTe. Here we show that observed magnetocapacitance oscillations probe—in contrast to magnetotransport—primarily the top surface. Capacitance measurements constitute thus a powerful tool to probe only one topological surface and to reconstruct its Landau level spectrum for different positions of the Fermi energy.

  13. Direct measurement of specific membrane capacitance in neurons.

    OpenAIRE

    Gentet, L.J.; Stuart, G J; Clements, J D

    2000-01-01

    The specific membrane capacitance (C(m)) of a neuron influences synaptic efficacy and determines the speed with which electrical signals propagate along dendrites and unmyelinated axons. The value of this important parameter remains controversial. In this study, C(m) was estimated for the somatic membrane of cortical pyramidal neurons, spinal cord neurons, and hippocampal neurons. A nucleated patch was pulled and a voltage-clamp step was applied. The exponential decay of the capacitative char...

  14. Quantum inductance and negative electrochemical capacitance at finite frequency

    OpenAIRE

    Wang, J.; Wang, B. G.; Guo, H

    2007-01-01

    We report on theoretical investigations of frequency dependent quantum capacitance. It is found that at finite frequency a quantum capacitor can be characterized by a classical RLC circuit with three parameters: a static electrochemical capacitance, a charge relaxation resistance, and a quantum inductance. The quantum inductance is proportional to the characteristic time scale of electron dynamics and due to its existence, the time dependent current can accumulate a phase delay and becomes la...

  15. Simultaneous capacitance and amperometric measurements of exocytosis: a comparison.

    OpenAIRE

    Oberhauser, A F; Robinson, I M; Fernandez, J. M.

    1996-01-01

    We measured the exocytotic response induced by flash photolysis of caged compounds in isolated mast cells and chromaffin cells. Vesicle fusion was measured by monitoring the cell membrane capacitance. The release of vesicular contents was followed by amperometry. In response to a GTP gamma S stimulus we found that the time integral of the amperometric current could be superimposed on the capacitance trace. This shows that the integrated amperometric signal provides an alternative method of me...

  16. Graphene-based quantum capacitance wireless vapor sensors

    OpenAIRE

    Deen, David A.; Olson, Eric J.; Ebrish, Mona A.; Koester, Steven J.

    2013-01-01

    A wireless vapor sensor based upon the quantum capacitance effect in graphene is demonstrated. The sensor consists of a metal-oxide-graphene variable capacitor (varactor) coupled to an inductor, creating a resonant oscillator circuit. The resonant frequency is found to shift in proportion to water vapor concentration for relative humidity (RH) values ranging from 1% to 97% with a linear frequency shift of 5.7 +- 0.3 kHz / RH%. The capacitance values extracted from the wireless measurements ag...

  17. Capacitive Coupling in Double-Circuit Transmission Lines

    Directory of Open Access Journals (Sweden)

    Zdenka Benesova

    2004-01-01

    Full Text Available The paper describes an algorithm for calculation of capacitances and charges on conductors in systems with earth wires and in double-circuit overhead lines with respect to phase arrangement. A balanced voltage system is considered. A suitable transposition of individual conductors enables to reduce the electric and magnetic fields in vicinity of overhead lines and to limit the inductive and capacitive linkage. The procedure is illustrated on examples the results of which lead to particular recommendations for designers.

  18. Calcium channel structural determinants of synaptic transmission between identified invertebrate neurons.

    Science.gov (United States)

    Spafford, J David; Munno, David W; Van Nierop, Pim; Feng, Zhong-Ping; Jarvis, Scott E; Gallin, Warren J; Smit, August B; Zamponi, Gerald W; Syed, Naweed I

    2003-02-01

    We report here that unlike what was suggested for many vertebrate neurons, synaptic transmission in Lymnaea stagnalis occurs independent of a physical interaction between presynaptic calcium channels and a functional complement of SNARE proteins. Instead, synaptic transmission in Lymnaea requires the expression of a C-terminal splice variant of the Lymnaea homolog to mammalian N- and P/Q-type calcium channels. We show that the alternately spliced region physically interacts with the scaffolding proteins Mint1 and CASK, and that synaptic transmission is abolished following RNA interference knockdown of CASK or after the injection of peptide sequences designed to disrupt the calcium channel-Mint1 interactions. Our data suggest that Mint1 and CASK may serve to localize the non-L-type channels at the active zone and that synaptic transmission in invertebrate neurons utilizes a mechanism for optimizing calcium entry, which occurs independently of a physical association between calcium channels and SNARE proteins.

  19. [Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

    NARCIS (Netherlands)

    Jonge, H.J. de; Gans, R.O.; Huls, G.A.

    2012-01-01

    Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate ab

  20. Specification of the Model 3 Entry Lexicon.

    Science.gov (United States)

    Rhode, Mary

    The Model 3 communication skills lexicon consists of three lists of words developed by the Southwest Regional Laboratory (SWRL) for use in communication skills instruction in K-6. This report documents the procedures followed in compiling the entry lexicon, the first component of the Model 3 communication skills lexicon. The entry lexicon is…

  1. Predicting the Diversity of Foreign Entry Modes

    DEFF Research Database (Denmark)

    Hashai, Niron; Geisler Asmussen, Christian; Benito, Gabriel;

    2007-01-01

    diversity across value chain activities and host markets. Analyzing a sample of Israeli based firms we show that larger firms exhibit a higher degree of entry mode diversity both across value chain activities and across host markets. Higher levels of knowledge intensity are also associated with more...... diversity in firms' entry modes across both dimensions....

  2. 19 CFR 4.8 - Preliminary entry.

    Science.gov (United States)

    2010-04-01

    ... enter, to commence lading and unlading operations prior to making formal entry. Preliminary entry may be accomplished electronically pursuant to an authorized electronic data interchange system, or by any other means... electronic equivalent of a complete Customs Form 1302 (Cargo Declaration), in the manner provided in §...

  3. Foreign Entry and Heterogeneous Growth of Firms

    DEFF Research Database (Denmark)

    Deng, Paul Duo; Jefferson, Gary H.

    We adopt the framework of Schumpeterian creative destruction formalized by Aghion et al. (2009) to analyze the impact of foreign entry on the productivity growth of domestic firms. In the face of foreign entry, domestic firms exhibit heterogeneous patterns of growth depending on their technologic...

  4. Optimizing the Materials Response in Humidity Capacitive Sensors

    Directory of Open Access Journals (Sweden)

    Elham Noroozi Afshar

    2015-10-01

    Full Text Available The number of humidity outputs on the cap of a cylindrical capacitance sensor is optimized by designing three different probes with direct and indirect windows. The time interval is measured within which 30-70 % humidity can influence the dielectric constant and conductivity of the capacitance when exposed to a range of relative humidity. It is then compared with a simple set-up including a simplified equivalent circuit. The direct probes had four and double outputs on the window of the cylindrical capacitive sensor while the indirect probe had a thin plastic layer only. We observed that the dielectric constant and its conductivity depend closely to the humidity outgoing pathway and also to the increasing rate of humidity between the capacitance plates. The final variation in the materials properties alters the capacitance of the sensor which is measured simply by a LCR. This technique presents a simple method for tracking the recovery and reliability of the humidity sensors over time and assists in optimizing and controlling the materials response to the relative environment humidity. As a result, by controlling the environment humidity rate (0.02 %/s., we could measure the increment rate of capacitance with accuracy of 0.01 pf/%.

  5. Switchless charge-discharge circuit for electrical capacitance tomography

    International Nuclear Information System (INIS)

    The main factor limiting the performance of electrical capacitance tomography (ECT) is an extremely low value of inter-electrode capacitances. The charge-discharge circuit is a well suited circuit for a small capacitance measurement due to its immunity to noise and stray capacitance, although it has a problem associated with a charge injected by the analogue switches, which results in a dc offset. This paper presents a new diode-based circuit for capacitance measurement in which a charge transfer method is realized without switches. The circuit was built and tested in one channel configuration with 16 multiplexed electrodes. The performance of the elaborated circuit and a comparison with a classic charge-discharge circuit are presented. The elaborated circuit can be used for sensors with inter-electrode capacitances not lower than 10 fF. The presented approach allows us to obtain a similar performance to the classic charge-discharge circuit, but has a simplified design. A lack of the need to synchronize the analogue switches in the transmitter and the receiver part of this circuit could be a desirable feature in the design of measurement systems integrated with electrodes. (paper)

  6. Thermal Soak Analysis of Earth Entry Vehicles

    Science.gov (United States)

    Agrawal, Parul; Sepka, Steven A.; Aliaga, Jose F.; Venkatapathy, Ethiraj; Samareh, Jamshid A.

    2012-01-01

    The Multi-Mission Earth Entry Vehicle project is developing an integrated tool called Multi Mission System Analysis for Planetary Entry Descent and Landing that will provide key technology solutions including mass sizing, aerodynamics, aerothermodynamics, and thermal and structural analysis for any given sample return mission. Thermal soak analysis and temperature predictions of various components including the payload container of the entry vehicle are part of the solution that this tool will offer to mission designers. The present paper focuses on the thermal soak analysis of an entry vehicle design based on the Mars Sample Return entry vehicle geometry and discusses a technical approach to develop parametric models for thermal soak analysis that will be integrated into the tool.

  7. Adaptive Text Entry for Mobile Devices

    DEFF Research Database (Denmark)

    Proschowsky, Morten Smidt

    -aware language models that is introduced in the thesis. YourText enables different language models to be combined to a new common language model. The framework is designed so it can be adapted to different text entry methods, thereby enabling the language model to be transferred between devices. Your...... for mobile devices and a framework for adaptive context-aware language models. Based on analysis of current text entry methods, the requirements to the new text entry methods are established. Transparent User guided Prediction (TUP) is a text entry method for devices with one dimensional touch input. It can...... to improve the models of human motor behaviour. TUP-Key is a variant of TUP, designed for 12 key phone keyboards. It is introduced in the thesis but has not been implemented or evaluated. Both text entry methods support adaptive context-aware language models. YourText is a framework for adaptive context...

  8. Functional separation of deep cytoplasmic calcium from subplasmalemmal space calcium in cultured human uterine smooth muscle cells.

    Science.gov (United States)

    Young, Roger C; Zhang, PeiSheng

    2004-07-01

    For smooth muscle, two important functions of free intracellular calcium (Ca(2+)(i)) are modulation of plasma membrane excitability properties and modulation of the contractile apparatus. As proposed by van Breemen, Ca(2+)(i) can be divided into the subplasmalemmal space (Ca(2+)(sps)) and the deep cytosol (Ca(2+)(d)) by the superficial calcium buffer barrier. Using these distinctions, Ca(2+)(sps) activates the large conductance calcium-activated potassium channel (BK), and Ca(2+)(d) binds calcium-dependent fluorescent probes in the cytoplasm. We present here combined fluorescence-patch clamp experiments designed to simultaneously assess Ca(2+)(d) and Ca(2+)(sps) in cultured human uterine smooth muscle cells. Open probabilities (P(o)) of the BK channel were measured using the cell-attached patch clamp technique. P(o) was used to approximate changes of [Ca(2+)(sps)]. Relative concentrations of Ca(2+)(d) were approximated by observing fluorescence of Calcium green-1 (F). Under control conditions, we found similar time courses for rises of P(o) and F following 10nM oxytocin (OT) addition. In parallel experiments, but with lanthanum (La(3+)) added to the bath to block transmembrane calcium flux, P(o) was only slightly affected, but F increases were delayed and blunted. These data paradoxically indicate that following OT stimulation, the primary source of calcium for Ca(2+)(sps) is internal stores, and calcium entry from the extracellular space is required to raise Ca(2+)(d). When cells were exposed to cyclopiazonic acid (CPA) to release SR calcium stores, P(o) increased slowly, then persisted at large values. The persistence of P(o) rises suggests that removal of calcium from the subplasmalemmal space is primarily via reuptake into the SR. In the presence of La(3+), OT-induced rises of F were slightly prolonged, suggesting that transmembrane calcium flux contributes to decreasing Ca(2+)(d), but is not the primary mechanism. In summary, these data demonstrate that Ca(2

  9. A QUALITATIVE ANALYSIS OF BIOMASS FLOW SENSING BEHAVIOR USING CAPACITIVE TECHNIQUE

    OpenAIRE

    Rumana Tasnim; Sheroz Khan; Musse Mohamud; Atika Arshad

    2016-01-01

    Flowsensing technology from today’s application perspective has gained significant research interest over the past few years. Among the existing sensing techniques, electrostatic and capacitive sensing techniques have proven promising although cable capacitance and stray capacitance cause inaccuracy while measuring very small capacitances. The existing measurement circuit model is complicated and has flawed electrode arrangement. By sensing very small capacitive variation, the developed capac...

  10. Inhibition of parathyroid hormone release by maitotoxin, a calcium channel activator

    International Nuclear Information System (INIS)

    Maitotoxin, a toxin derived from a marine dinoflagellate, is a potent activator of voltage-sensitive calcium channels. To further test the hypothesis that inhibition of PTH secretion by calcium is mediated via a calcium channel we studied the effect of maitotoxin on dispersed bovine parathyroid cells. Maitotoxin inhibited PTH release in a dose-dependent fashion, and inhibition was maximal at 1 ng/ml. Chelation of extracellular calcium by EGTA blocked the inhibition of PTH by maitotoxin. Maitotoxin enhanced the effects of the dihydropyridine calcium channel agonist (+)202-791 and increased the rate of radiocalcium uptake in parathyroid cells. Pertussis toxin, which ADP-ribosylates and inactivates a guanine nucleotide regulatory protein that interacts with calcium channels in the parathyroid cell, did not affect the inhibition of PTH secretion by maitotoxin. Maitotoxin, by its action on calcium channels allows entry of extracellular calcium and inhibits PTH release. Our results suggest that calcium channels are involved in the release of PTH. Inhibition of PTH release by maitotoxin is not sensitive to pertussis toxin, suggesting that maitotoxin may act distal to the site interacting with a guanine nucleotide regulatory protein, or maitotoxin could interact with other ions or second messengers to inhibit PTH release

  11. An Analytical Model for Fringing Capacitance in Double gate Hetero Tunnel FET and Analysis of effect of Traps and Oxide charges on Fringing Capacitance

    Directory of Open Access Journals (Sweden)

    Brinda Bhowmick

    2012-03-01

    Full Text Available In this paper fringe capacitance of double hetero gate Tunnel FET has been studied. The physical modelfor fringe capacitance is derived considering source gate overlap and gate drain non overlap. Inerface trap charge and oxide charges are also introduced under positive bias stress and hot carrier stress and their effect on fringe capacitance is also studied. The fringe capacitance is significant speed limiter in Double gate technology. The model is tested by comparing with simulation results obtained from Sentauras TCADsimulations.

  12. An Analytical Model for Fringing Capacitance in Double gate Hetero Tunnel FET and Analysis of effect of Traps and Oxide charges on Fringing Capacitance

    OpenAIRE

    Brinda Bhowmick; Srimanta Baishya

    2012-01-01

    In this paper fringe capacitance of double hetero gate Tunnel FET has been studied. The physical model for fringe capacitance is derived considering source gate overlap and gate drain non overlap. Inerface trap charge and oxide charges are also introduced under positive bias stress and hot carrier stress and their effect on fringe capacitance is also studied. The fringe capacitance is significant speed limiter in Double gate technology. The model is tested by comparing with simulation results...

  13. Osteoclast cytosolic calcium, regulated by voltage-gated calcium channels and extracellular calcium, controls podosome assembly and bone resorption

    Science.gov (United States)

    Miyauchi, A.; Hruska, K. A.; Greenfield, E. M.; Duncan, R.; Alvarez, J.; Barattolo, R.; Colucci, S.; Zambonin-Zallone, A.; Teitelbaum, S. L.; Teti, A.

    1990-01-01

    The mechanisms of Ca2+ entry and their effects on cell function were investigated in cultured chicken osteoclasts and putative osteoclasts produced by fusion of mononuclear cell precursors. Voltage-gated Ca2+ channels (VGCC) were detected by the effects of membrane depolarization with K+, BAY K 8644, and dihydropyridine antagonists. K+ produced dose-dependent increases of cytosolic calcium ([Ca2+]i) in osteoclasts on glass coverslips. Half-maximal effects were achieved at 70 mM K+. The effects of K+ were completely inhibited by dihydropyridine derivative Ca2+ channel blocking agents. BAY K 8644 (5 X 10(-6) M), a VGCC agonist, stimulated Ca2+ entry which was inhibited by nicardipine. VGCCs were inactivated by the attachment of osteoclasts to bone, indicating a rapid phenotypic change in Ca2+ entry mechanisms associated with adhesion of osteoclasts to their resorption substrate. Increasing extracellular Ca2+ ([Ca2+]e) induced Ca2+ release from intracellular stores and Ca2+ influx. The Ca2+ release was blocked by dantrolene (10(-5) M), and the influx by La3+. The effects of [Ca2+]e on [Ca2+]i suggests the presence of a Ca2+ receptor on the osteoclast cell membrane that could be coupled to mechanisms regulating cell function. Expression of the [Ca2+]e effect on [Ca2+]i was similar in the presence or absence of bone matrix substrate. Each of the mechanisms producing increases in [Ca2+]i, (membrane depolarization, BAY K 8644, and [Ca2+]e) reduced expression of the osteoclast-specific adhesion structure, the podosome. The decrease in podosome expression was mirrored by a 50% decrease in bone resorptive activity. Thus, stimulated increases of osteoclast [Ca2+]i lead to cytoskeletal changes affecting cell adhesion and decreasing bone resorptive activity.

  14. Arachidonic acid and calcium metabolism in rnelittin stimulated neutrophils

    Directory of Open Access Journals (Sweden)

    Ole H. Nielsen

    1992-01-01

    Full Text Available Melittin, the predominant fraction of bee venom proteins, was studied in an experimental model of human neutrophil granulocytes to reveal its influence on eicosanoid release, metabolism and receptor function in relation to intracellular calcium metabolism. Melittin (2 μmol/l was as potent as the calcium ionophore A23187 (10 μmol/l for activation of 5-lipoxygenase, releasing arachidonate only from phosphatidyl-choline and phosphatidyl-ethanolamine of cellular membranes, as judged from the decreases in radioactivity by 15.4% and 30.5%, respectively. The mechanism responsible for the release of arachidonate from cellular membranes is closely coupled to cellular calcium metabolism, and melittin was found to promote calcium entry through receptor gated calcium channels, probably due to an activation of phospholipase A2. Furthermore, a down-regulation of leukotriene B4 receptors was seen. The maximal number of binding sites per cell was reduced from a median of 1520 to 950 with melittin (1 μmol/l. The study has revealed some factors important for the inflammatory mechanisms mediated by melittin.

  15. Iron entry in neurons and astrocytes: a link with synaptic activity

    Directory of Open Access Journals (Sweden)

    Franca eCodazzi

    2015-06-01

    Full Text Available Iron plays a fundamental role in the development of the central nervous system (CNS as well as in several neuronal functions including synaptic plasticity. Accordingly, neuronal iron supply is tightly controlled: it depends not only on transferrin-bound iron but also on non-transferrin-bound iron (NTBI, which represents a relevant quote of the iron physiologically present in the cerebrospinal fluid (CSF. Different calcium permeable channels as well as the divalent metal transporter 1 (DMT1 have been proposed to sustain NTBI entry in neurons and astrocytes even though it remains an open issue. In both cases, it emerges that the control of iron entry is tightly linked to synaptic activity. The iron-induced oxidative tone can, in physiological conditions, positively influence the calcium levels and thus the synaptic plasticity. On the other hand, an excess of iron, with the ensuing uncontrolled production of reactive oxygen species (ROS, is detrimental for neuronal survival. A protective mechanism can be played by astrocytes that, more resistant to oxidative stress, can uptake iron, thereby buffering its concentration in the synaptic environment. This competence is potentiated when astrocytes undergo activation during neuroinflammation and neurodegenerative processes. In this minireview we focus on the mechanisms responsible for NTBI entry in neurons and astrocytes and on how they can be modulated during synaptic activity. Finally, we speculate on the relevance they may have in both physiological and pathological conditions.

  16. Modeling late entry bias in survival analysis.

    Science.gov (United States)

    Matsuura, Masaaki; Eguchi, Shinto

    2005-06-01

    In a failure time analysis, we sometimes observe additional study subjects who enter during the study period. These late entries are treated as left-truncated data in the statistical literature. However, with real data, there is a substantial possibility that the delayed entries may have extremely different hazards compared to the other standard subjects. We focus on a situation in which such entry bias might arise in the analysis of survival data. The purpose of the present article is to develop an appropriate methodology for making inference about data including late entries. We construct a model that includes parameters for the effect of delayed entry bias having no specification for the distribution of entry time. We also discuss likelihood inference based on this model and derive the asymptotic behavior of estimates. A simulation study is conducted for a finite sample size in order to compare the analysis results using our method with those using the standard method, where independence between entry time and failure time is assumed. We apply this method to mortality analysis among atomic bomb survivors defined in a geographical study region. PMID:16011705

  17. Study on capacitance evolving mechanism of polypyrrole during prolonged cycling.

    Science.gov (United States)

    Wang, JingPing; Xu, Youlong; Wang, Jie; Zhu, Jianbo; Bai, Yang; Xiong, Lilong

    2014-02-01

    A simple model on the evolution mechanism of PPy capacitance during prolonged cycling offers a reasonably description on the rapid increase and decay of PPy capacitance in 1 M 1-ethyl-3-methylimidazolium tetrafluoroborate/propylene carbonate (EtMeImBF4/PC). The capacitance of PPy films reached a very high specific capacitance of 420 F·g(-1) after 15 cycles when they worked in 1 M MeEt3ImBF4/PC. However, the capacitance rapidly decreased to 5% after only 400 cycles. The electronic conductivity and protonation level on the nitrogen site of PPy films rapidly decreased with the increase of cyclic number. The salt of EtMeImBF4 was monitored in PPy matrix by FTIR spectra after 400 cycles. The EQCM results indicated that a lot of 1-ethyl-3-methylimidazolium cations (EtMeIm(+)) were inserted during reduction process and retained in PPy matrix. The detained EtMeIm(+) cations bonded with doped p-toluenesulfonate anions (PTS(-)) in PPy matrix or BF4(-) anions from electrolyte and formed salts. Small amount of salts in PPy matrix can open more channels of ion insertion and resulted in a very high capacitance after 15 cycles. The continuous combination of detained EtMeIm(+) cations with doping anions of PTS(-) resulted in the rapid decrease of PPy protonation level on the nitrogen site and formation of compensate semiconductor state in PPy matrix. This should be responsible for the rapid decay of PPy conductivity and capacitance. The continuous accumulation of salts resulted in the great increase of PPy internal resistance. PMID:24428582

  18. Optimal firm growth under the threat of entry

    OpenAIRE

    Peter M. Kort; Wrzaczek, Stefan

    2015-01-01

    The paper studies the incumbent-entrant problem in a fully dynamic setting. We find that under an open-loop information structure the incumbent anticipates entry by overinvesting, whereas in the Markov perfect equilibrium the incumbent slightly underinvests in the period before the entry. The entry cost level where entry accommodation passes into entry deterrence is lower in the Markov perfect equilibrium. Further we find that the incumbent’s capital stock level needed to deter entry is hump ...

  19. Binding of [125I]iodipine to parathyroid cell membranes: Evidence of a dihydropyridine-sensitive calcium channel

    International Nuclear Information System (INIS)

    The parathyroid cell is unusual, in that an increase in extracellular calcium concentrations inhibits PTH release. Calcium channels are glycoproteins that span cell membranes and allow entry of extracellular calcium into cells. We have demonstrated that the calcium channel agonist (+)202-791, which opens calcium channels, inhibits PTH release and that the antagonist (-)202-791, which closes calcium channels, stimulates PTH release. To identify the calcium channels responsible for these effects, we used a radioligand that specifically binds to calcium channels. Bovine parathyroid cell membranes were prepared and incubated under reduced lighting with [125I] iodipine (SA, 2000 Ci/mmol), which recognizes 1,4-dihydropyridine-sensitive calcium channels. Bound ligand was separated from free ligand by rapid filtration through Whatman GF/B filters. Nonspecific binding was measured by the inclusion of nifedipine at 10 microM. Specific binding represented approximately 40% of the total binding. The optimal temperature for [125I] iodipine binding was 4 C, and binding reached equilibrium by 30 min. The equilibrium dissociation constant (Kd) was approximately 550 pM, and the maximum number of binding sites was 780 fmol/mg protein. Both the calcium channel agonist (+)202-791 and antagonist (-)202-791 competitively inhibited [125I] iodipine binding, with 50% inhibition concentrations of 20 and 300 nM, respectively. These data indicate the presence of dihydropyridine-sensitive calcium channels on parathyroid cell membranes

  20. A Calcium-Dependent Protein Kinase Interactswith and Activates A Calcium Channel toRequlate Pollen Tube Growth

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    ABSTRACT Calcium, as a ubiquitous second messenger, plays essential roles in tip-growing cells, such as animal neu-rons, plant pollen tubes, and root hairs. However, little is known concerning the regulatory mechanisms that code anddecode Ca2+ signals in plants. The evidence presented here indicates that a calcium-dependent protein kinase, CPK32,controls polar growth of pollen tubes. Overexpression of CPK32 disrupted the polar growth along with excessive Ca2+accumulation in the tip. A search of downstream effector molecules for CPK32 led to identification of a cyclic nucleotide-gated channel, CNGC18, as an interacting partner for CPK32. Co-expression of CPK32 and CNGC18 resulted in activationof CNGC18 in Xenopus oocytes where expression of CNGC18 alone did not exhibit significant calcium channel activity.Overexpression of CNGC18 produced a growth arrest phenotype coupled with accumulation of calcium in the tip, simi-lar to that induced by CPK32 overexpression. Co-expression of CPK32 and CNGC18 had a synergistic effect leading tomore severe depolarization of pollen tube growth. These results provide a potential feed-forward mechanism in whichcalcium-activated CPK32 activates CNGC18, further promoting calcium entry during the elevation phase of Ca2+ oscilla-tions in the polar growth of pollen tubes.

  1. Physical security workshop summary: entry control

    International Nuclear Information System (INIS)

    Entry control hardware has been used extensively in the past to assist security forces in separating the authorized from the unauthorized at the plant perimeter. As more attention is being focused on the insider threat, these entry control elements are being used to extend the security inspectors' presence into the plant by compartmentalizing access and monitoring vital components. This paper summarizes the experiences expressed by the participants at the March 16 to 19, 1982 INMM Physical Protection Workshop in utilizing access control and contraband detection hardware for plant wide entry control applications

  2. Entry Regulation under Asymmetric Information about Demand

    Directory of Open Access Journals (Sweden)

    Paula Sarmento

    2010-01-01

    Full Text Available We investigate how an incumbent firm can use the regulatory policy about entry and the informational advantage to protect his market position. This question is studied through the construction of a signalling game where we assume that the regulator has less information about demand than the firms. We conclude that there is a pooling equilibrium and partially separating equilibria in which entry is deterred and, if demand is high, there will be insufficient entry. The final effect on welfare depends on the tradeoff between short-run benefits (lower price and long-run losses (weaker competition.

  3. 1994 Entry-Level Athletic Training Salaries

    OpenAIRE

    Moss, Crayton L.

    1996-01-01

    In this study, I examined salaries for entry-level positions in athletic training during the year 1994. An entry-level position was defined as a position to be filled with an athletic trainer certified by the NATA, with no full-time paid employment experience. According to the “Placement Vacancy Notice” (NATA, Dallas, TX) and “BYLINE” (Athletic Trainer Services, Inc, Mt Pleasant, MI), there were 432 entry-level vacancies in hospital/clinics, college/universities, and high school settings. A t...

  4. Structure and Function of a Genetically Engineered Mimic of a Nonenveloped Virus Entry Intermediate

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Manidipa; Speir, Jeffrey A.; Kwan, Maggie H.; Huang, Rick; Aryanpur, Peyman P.; Bothner, Brian; Johnson, John E. (UCSD); (Montana)

    2010-04-07

    Divalent metal ions are components of numerous icosahedral virus capsids. Flock House virus (FHV), a small RNA virus of the family Nodaviridae, was utilized as an accessible model system with which to address the effects of metal ions on capsid structure and on the biology of virus-host interactions. Mutations at the calcium-binding sites affected FHV capsid stability and drastically reduced virus infectivity, without altering the overall architecture of the capsid. The mutations also altered the conformation of gamma, a membrane-disrupting, virus-encoded peptide usually sequestered inside the capsid, by increasing its exposure under neutral pH conditions. Our data demonstrate that calcium binding is essential for maintaining a pH-based control on gamma exposure and host membrane disruption, and they reveal a novel rationale for the metal ion requirement during virus entry and infectivity. In the light of the phenotypes displayed by a calcium site mutant of FHV, we suggest that this mutant corresponds to an early entry intermediate formed in the endosomal pathway.

  5. Negative capacitance for ultra-low power computing

    Science.gov (United States)

    Khan, Asif Islam

    Owing to the fundamental physics of the Boltzmann distribution, the ever-increasing power dissipation in nanoscale transistors threatens an end to the almost-four-decade-old cadence of continued performance improvement in complementary metal-oxide-semiconductor (CMOS) technology. It is now agreed that the introduction of new physics into the operation of field-effect transistors---in other words, "reinventing the transistor'"--- is required to avert such a bottleneck. In this dissertation, we present the experimental demonstration of a novel physical phenomenon, called the negative capacitance effect in ferroelectric oxides, which could dramatically reduce power dissipation in nanoscale transistors. It was theoretically proposed in 2008 that by introducing a ferroelectric negative capacitance material into the gate oxide of a metal-oxide-semiconductor field-effect transistor (MOSFET), the subthreshold slope could be reduced below the fundamental Boltzmann limit of 60 mV/dec, which, in turn, could arbitrarily lower the power supply voltage and the power dissipation. The research presented in this dissertation establishes the theoretical concept of ferroelectric negative capacitance as an experimentally verified fact. The main results presented in this dissertation are threefold. To start, we present the first direct measurement of negative capacitance in isolated, single crystalline, epitaxially grown thin film capacitors of ferroelectric Pb(Zr0.2Ti0.8)O3. By constructing a simple resistor-ferroelectric capacitor series circuit, we show that, during ferroelectric switching, the ferroelectric voltage decreases, while the stored charge in it increases, which directly shows a negative slope in the charge-voltage characteristics of a ferroelectric capacitor. Such a situation is completely opposite to what would be observed in a regular resistor-positive capacitor series circuit. This measurement could serve as a canonical test for negative capacitance in any novel

  6. CALCIUM-INDUCED SUPRAMOLECULAR STRUCTURES IN THE CALCIUM CASEINATE SYSTEM

    Science.gov (United States)

    The molecular details deciphering the spontaneous calcium-induced protein aggregation process in the calcium caseinate system remain obscure. Understanding this complex process could lead to potential new applications of this important food ingredient. In this work, we studied calcium-induced supra...

  7. Simulating Capacitances to Silicon Quantum Dots: Breakdown of the Parallel Plate Capacitor Model

    Science.gov (United States)

    Thorbeck, Ted; Fujiwara, Akira; Zimmerman, Neil M.

    2012-09-01

    Many electrical applications of quantum dots rely on capacitively coupled gates; therefore, to make reliable devices we need those gate capacitances to be predictable and reproducible. We demonstrate in silicon nanowire quantum dots that gate capacitances are reproducible to within 10% for nominally identical devices. We demonstrate the experimentally that gate capacitances scale with device dimensions. We also demonstrate that a capacitance simulator can be used to predict measured gate capacitances to within 20%. A simple parallel plate capacitor model can be used to predict how the capacitances change with device dimensions; however, the parallel plate capacitor model fails for the smallest devices because the capacitances are dominated by fringing fields. We show how the capacitances due to fringing fields can be quickly estimated.

  8. Capacitance-Based Frequency Adjustment of Micro Piezoelectric Vibration Generator

    Directory of Open Access Journals (Sweden)

    Xinhua Mao

    2014-01-01

    Full Text Available Micro piezoelectric vibration generator has a wide application in the field of microelectronics. Its natural frequency is unchanged after being manufactured. However, resonance cannot occur when the natural frequencies of a piezoelectric generator and the source of vibration frequency are not consistent. Output voltage of the piezoelectric generator will sharply decline. It cannot normally supply power for electronic devices. In order to make the natural frequency of the generator approach the frequency of vibration source, the capacitance FM technology is adopted in this paper. Different capacitance FM schemes are designed by different locations of the adjustment layer. The corresponding capacitance FM models have been established. Characteristic and effect of the capacitance FM have been simulated by the FM model. Experimental results show that the natural frequency of the generator could vary from 46.5 Hz to 42.4 Hz when the bypass capacitance value increases from 0 nF to 30 nF. The natural frequency of a piezoelectric vibration generator could be continuously adjusted by this method.

  9. Nonlinear dynamics of capacitive charging and desalination by porous electrodes.

    Science.gov (United States)

    Biesheuvel, P M; Bazant, M Z

    2010-03-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by supercapacitors, water desalination and purification by capacitive deionization, and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) valid in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory for the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes with different time scales: (i) in the "supercapacitor regime" of small voltages and/or early times, the porous electrode acts like a transmission line, governed by a linear diffusion equation for the electrostatic potential, scaled to the RC time of a single pore, and (ii) in the "desalination regime" of large voltages and long times, the porous electrode slowly absorbs counterions, governed by coupled, nonlinear diffusion equations for the pore-averaged potential and salt concentration. PMID:20365735

  10. Continuous capacitance-voltage spectroscopy mapping for scanning microwave microscopy.

    Science.gov (United States)

    Moertelmaier, M; Huber, H P; Rankl, C; Kienberger, F

    2014-01-01

    A new method, scanning sawtooth capacitance spectroscopy (SSCS), is proposed to measure a map of capacitance/voltage curves (C-V) by applying a low frequency voltage sawtooth signal (20-100 Hz) to the AFM tip while scanning. For this a scanning microwave microscope (SMM) is used to acquire calibrated capacitance data in the high frequency range of 1-20 GHz. While the capacitance is acquired pixel by pixel, the applied voltage signal is recorded as well, and each pixel of the capacitance is assigned the corresponding voltage value. Assuming the voltage variable is smooth over time, adjacent pixels within a scan line will have similar voltage values and a small sequence of neighboring pixels can be combined into a virtual C-V spectroscopy curve. With standard SMM operation parameters roughly 26,000 C-V curves can be acquired within few minutes data acquisition time. The method is demonstrated for n-type and p-type silicon semiconductor samples and can be applied to other samples including new materials and bio-membranes. PMID:24012937

  11. Tracking cancer cell proliferation on a CMOS capacitance sensor chip.

    Science.gov (United States)

    Prakash, Somashekar Bangalore; Abshire, Pamela

    2008-05-15

    We report a novel technique for assessing cell proliferation that employs integrated capacitance sensors for monitoring the growth of anchorage-dependent living cells. The sensors measure substrate coupling capacitances of cells cultured on-chip in a standard in vitro environment. The biophysical phenomenon underlying the capacitive behavior of cells is the counterionic polarization around the insulating cell bodies when exposed to weak, low frequency electric fields. The sensors employ charge sharing for mapping sensed capacitance values in the fF range to output voltage signals. The sensor chip has been fabricated in a commercially available 0.5microm, 2-poly 3-metal CMOS technology. We report experimental results demonstrating sensor response to the adhesion of MDA-MB-231 breast cancer cells followed by their proliferation on the chip surface. On-chip capacitance sensing offers a non-invasive, label-free, easy-to-use, miniaturized technique with real-time monitoring capability for tracking cell proliferation in vitro. PMID:18281207

  12. Development and application of a real-time capacitive sensor.

    Science.gov (United States)

    Wongkittisuksa, Booncharoen; Limsakul, Chusak; Kanatharana, Proespichaya; Limbut, Warakorn; Asawatreratanakul, Punnee; Dawan, Supaporn; Loyprasert, Suchera; Thavarungkul, Panote

    2011-01-15

    A real-time capacitive sensor based on a potentiostatic step method was developed. It can display in real-time the evoked current waveform, capacitance and the electrical resistance of elements serially connected to the insulation layer on the electrode as a function of time as well as the ohmic resistance of the insulation layer. These features enable the user to observe the association and dissociation of the affinity binding pairs and to evaluate the insulating property of the electrode surface during measurement. The system allows the setting of potential pulse height, pulse interval, gain, filter, and sampling frequency, enabling the system to be more flexible. The performance of the system was firstly evaluated with equivalent circuits. Under suitable parameter settings it provided good accuracy of both the capacitance and resistance. Using the affinity binding pair of human serum albumin (HSA) and anti human serum albumin (anti-HSA) the measured capacitance change was used for the direct detection of HSA. The developed system provided the same sensitivity as the commercially available potentiostat (P>0.05). The proposed system was then applied to analyse HSA in real urine samples and the results agreed well with the immunoturbidimetric assay (P>0.05). The proposed system can be applied for capacitance measurement to directly detect other target analytes using different affinity binding pairs. Other applications such as kinetics analysis of the interaction between affinity bindings, thickness analysis, and the study of the insulation property of the modified layer are also promising. PMID:21087852

  13. Recent advances in understanding the capacitive storage in microporous carbons

    Energy Technology Data Exchange (ETDEWEB)

    Daffos, B.; Taberna, P.L. [Universite de Toulouse, CIRIMAT, UMR-CNRS 5085, Toulouse (France); Gogotsi, Y. [Department of Materials Science and Engineering, A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, PA (United States); Simon, P.

    2010-10-15

    This paper presents a review of our recent work on capacitance of carbide-derived carbons (CDCs). Specific capacitance as high as 14 {mu}F cm{sup -2} or 160 F g{sup -1} was achieved using CDCs with tailored subnanometer pore size, which is significantly higher than 6 {mu}F cm{sup -2} or 100 F g{sup -1} for conventional activated carbons. Such high capacitance was obtained in several types of organic electrolytes with or without solvent. A maximum is obtained for the carbons with the mean pore size close to the bare ion size, ruling out the traditional point of view that mesoporosity is highly required for maximum capacitance. Surprisingly, carbons with subnanometer porosity exhibit high capacitance retention, since only a 10% loss is measured when 6 A g{sup -1} discharge is drawn. These findings show the importance of fitting the ion size with the mean pore size. The double layer theory falls short to explain such charge storage mechanisms at the nanometer scale; thus atomistic modelling is required to find out an alternative charge storage model. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  14. Logarithmic derivative method and system for capacitance measurement

    Science.gov (United States)

    Wu, Yichun; Wang, Lingzhi; Cai, Yuanfeng; Wu, Cunqiao

    2015-08-01

    A novel method based on logarithmic derivative is introduced to analyze multi-lifetime decay. As the discharge voltage signal of a RC circuit is a special kind of multi-lifetime exponential decay, the logarithmic derivative method can be used to measure single capacitance and multiple capacitances. With the logarithmic derivative method, a log(t) curve strongly peaked at precisely log(τ) is obtained, where the lifetime τ equals to RC. In a measurement system, if the resistance R is known, then the capacitance under test can be calculated. A logarithmic derivative curve fitting method is also presented, which has better anti-noise capability than the method that simply finds the maximum data on the peak. The curve fitting method can also be used for multiple capacitors measurement. To measure small capacitances, a large enough time window of the measuring instrument is required. Based on a field programmable gate array and a high speed analog-to-digital converter, a measurement system is developed. This system can provide the 16-bit resolution with sampling rate up to 250 MHz, which has a large enough time window for measuring lifetime shorter than 10-8 s. To reduce the amount of data needed to be stored and the noise due to the derivative treatment of transient data, the interpolation and noise-filter algorithms are employed. Experiments indicate that the logarithmic derivative method and system are suitable for the measurement of capacitances discharge and other exponential decay processes.

  15. Low-Temperature Scanning Capacitance Probe for Imaging Electron Motion

    International Nuclear Information System (INIS)

    Novel techniques to probe electronic properties at the nanoscale can shed light on the physics of nanoscale devices. In particular, studying the scattering of electrons from edges and apertures at the nanoscale and imaging the electron profile in a quantum dot, have been of interest [1]. In this paper, we present the design and implementation of a cooled scanning capacitance probe that operates at liquid He temperatures to image electron waves in nanodevices. The conducting tip of a scanned probe microscope is held above the nanoscale structure, and an applied sample-to-tip voltage creates an image charge that is measured by a cooled charge amplifier [2] adjacent to the tip. The circuit is based on a low-capacitance, high- electron-mobility transistor (Fujitsu FHX35X). The input is a capacitance bridge formed by a low capacitance pinched-off HEMT transistor and tip-sample capacitance. We have achieved low noise level (0.13 e/VHz) and high spatial resolution (100 nm) for this technique, which promises to be a useful tool to study electronic behavior in nanoscale devices

  16. A sensor for calcium uptake

    OpenAIRE

    Collins, Sean; Meyer, Tobias

    2010-01-01

    Mitochondria — the cell’s power plants — increase their energy production in response to calcium signals in the cytoplasm. A regulator of the elusive mitochondrial calcium channel has now been identified.

  17. Children's Bone Health and Calcium

    Science.gov (United States)

    ... Trials Resources and Publications Children's Bone Health and Calcium: Condition Information Skip sharing on social media links ... straight, walk, run, and lead an active life. Calcium is one of the key dietary building blocks ...

  18. Entry tank calibration in TOR pilot plant

    International Nuclear Information System (INIS)

    The objective of this communication is the description of calibration measurements used for determining the uranium and plutonium mass entry in the fast neutron fuel reprocessing pilot plant (TOR) of Marcoule

  19. The Effects of Entry in Bilateral Oligopoly

    Directory of Open Access Journals (Sweden)

    Alex Dickson

    2013-06-01

    Full Text Available The purpose of this paper is to study the effects of entry into the market for a single commodity in which both sellers and buyers are permitted to interact strategically. With the inclusion of an additional seller, the market is quasi-competitive: the price falls and volume of trade increases, as expected. However, contrary to the conventional wisdom, existing sellers’ payoffs may increase. The conditions under which entry by new sellers raises the equilibrium payoffs of existing sellers are derived. These depend in an intuitive way on the elasticity of a strategic analog of demand and the market share of existing sellers, and encompass entirely standard economic environments. Similar results are derived relating to the entry of additional buyers and the effects of entry on both sides of the market are investigated.

  20. Integrated Entry Guidance for Reusable Launch Vehicle

    Institute of Scientific and Technical Information of China (English)

    NING Guo-dong; ZHANG Shu-guang; FANG Zhen-ping

    2007-01-01

    A method for the implementation of integrated three-degree-of-freedom constrained entry guidance for reusable launch vehicle is presented. Given any feasible entry conditions, terminal area energy management interface conditions, and the reference trajectory generated onboard then, the method can generate a longitudinal guidance profile rapidly, featuring linear quadratic regular method and a proportional-integral-derivative tracking law with time-varying gains, which satisfies all the entry corridor constraints and meets the requirements with high precision. Afterwards, by utilizing special features of crossrange parameter, establishing bank-reversal corridor,and determining bank-reversals according to dynamically adjusted method, the algorithm enables the lateral entry guidance system to fly a wide range of missions and provides reliable and good performance in the presence of significant aerodynamic modeling uncertainty.Fast trajectory guidance profiles and simulations with a reusable launch vehicle model for various missions and aerodynamic uncertainties are presented to demonstrate the capacity and reliability of this method.

  1. Market entry strategies into the BRIC countries

    DEFF Research Database (Denmark)

    Boyd, Britta; Dyhr Ulrich, Anna Marie

    2014-01-01

    Based on a sample of 177 exporting SMEs, this study investigates what market entry strategy is used by Danish family and non-family businesses. From a resource-based view, three critical internal factors (risk, flexibility and control) affecting the entry mode choice into the BRIC markets...... are analysed. The effective management of firms’ resources and capabilities is influenced by the perception of these internal factors when expanding into foreign markets. Our results confirmed that family firms build up longer lasting relationships in the host country by choosing high commitment entry modes...... when entering the BRIC markets. In contrast, family firms choose high commitment entry modes which involve high risk and low flexibility when entering the BRIC markets. Further implications discuss the suitability of export strategies to BRIC markets for managers of Danish family and non-family firms....

  2. Border Crossing/Entry Data - Boarder Crossing

    Data.gov (United States)

    Department of Transportation — Border Crossing/Entry Data provides summary statistics for incoming crossings at the U.S.-Canadian and the U.S.-Mexican border at the port level. Data are available...

  3. Calcium ion channel and epilepsy

    Institute of Scientific and Technical Information of China (English)

    Yudan Lü; Weihong Lin; Dihui Ma

    2006-01-01

    OBJECTIVE: To review the relationship between calcium ion channel and epilepsy for well investigating the pathogenesis of epilepsy and probing into the new therapeutic pathway of epilepsy.DATA SOURCES: A computer-based online research Calcium ion channel and epilepsy related articles published between January 1994 and December 2006 in the CKNI and Wanfang database with the key words of "calcium influxion, epilepsy, calcium-channel blocker". The language was limited to Chinese. At the same time,related articles published between January 1993 and December 2006 in Pubmed were searched for on online with the key words of "calcium influxion, epilepsy" in English.STUDY SELECTION: The materials were selected firstly. Inclusive criteria: ① Studies related to calcium ion channel and the pat1hogenesis of epilepsy. ② Studies on the application of calcium ion channel blocker in the treatment of epilepsy. Exclusive criteria: repetitive or irrelated studies.DATA EXTRACTION: According to the criteria, 123 articles were retrieved and 93 were excluded due to repetitive or irrelated studies. Altogether 30 articles met the inclusive criteria, 11 of them were about the structure and characters of calcium ion channel, 10 about calcium ion channel and the pathogenesis of epilepsy and 9 about calcium blocker and the treatment of epilepsy.DATA SYNTHESIS: Calcium ion channels mainly consist of voltage dependent calcium channel and receptor operated calcium channel. Depolarization caused by voltage gating channel-induced influxion is the pathological basis of epileptic attack, and it is found in many studies that many anti-epileptic drugs have potential and direct effect to rivalizing voltage-dependent calcium ion channel.CONCLUSION: Calcium influxion plays an important role in the seizure of epilepsy. Some calcium antagonists seen commonly are being tried in the clinical therapy of epilepsy that is being explored, not applied in clinical practice. If there are enough evidences to

  4. Foreign Market Entry: Production-Related Strategies

    OpenAIRE

    Ming-Je Tang; Chwo-Ming Joseph Yu

    1990-01-01

    This paper examines the profit to a firm of different production-related strategies for entering a foreign market. The entry strategies examined are foreign direct investment, exclusive licensing, multiple licensing, joint venture, and a combination of joint venture and licensing. It is shown that even though the entering firm is able to charge the optimal licensing fee, foreign direct investment generates the highest profit and is thus the dominant entry strategy in many contexts. This paper...

  5. Predecessors of Double-Entry Accounting

    OpenAIRE

    Mykhaylo Kuter; Maryna Gurskaya; Artem Musaelyan

    2013-01-01

    The article covers analysis of some historically significant issues of accounting development in the home-country of contemporary accounting made with reference to the archived materials found in Italy. In particular, the issue of purpose and order of taking entries in the book titled 'RICORDANZE' ('Memorials') has been considered. Resulting from the analysis done, the significance has been grounded for keeping accounting records which do not subject to double-entry principle thus being busin...

  6. Entry and exit decisions under uncertainty

    DEFF Research Database (Denmark)

    Kongsted, Hans Christian

    1996-01-01

    This paper establishes the general deterministic limit that corresponds to Dixit's model of entry and exit decisions under uncertainty. The interlinked nature of decisions is shown to be essential also in the deterministic limit. A numerical example illustrates the result......This paper establishes the general deterministic limit that corresponds to Dixit's model of entry and exit decisions under uncertainty. The interlinked nature of decisions is shown to be essential also in the deterministic limit. A numerical example illustrates the result...

  7. Developing Quantitative Models for Auditing Journal Entries

    OpenAIRE

    Argyrou, Argyris

    2013-01-01

    The thesis examines how the auditing of journal entries can detect and prevent financial statement fraud. Financial statement fraud occurs when an intentional act causes financial statements to be materially misstated. Although it is not a new phenomenon, financial statement fraud has attracted much publicity in the wake of numerous cases of financial malfeasance (e.g. ENRON, WorldCom). Existing literature has provided limited empirical evidence on the link between auditing journal entrie...

  8. Solar Imagery - Chromosphere - Calcium

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset consists of full-disk images of the sun in Calcium (Ca) II K wavelength (393.4 nm). Ca II K imagery reveal magnetic structures of the sun from about...

  9. Calcium aluminate in alumina

    Science.gov (United States)

    Altay, Arzu

    The properties of ceramic materials are determined not only by the composition and structure of the phases present, but also by the distribution of impurities, intergranular films and second phases. The phase distribution and microstructure both depend on the fabrication techniques, the raw materials used, the phase-equilibrium relations, grain growth and sintering processes. In this dissertation research, various approaches have been employed to understand fundamental phenomena such as grain growth, impurity segregation, second-phase formation and crystallization. The materials system chosen was alumina intentionally doped with calcium. Atomic-scale structural analyses of grain boundaries in alumina were carried on the processed samples. It was found that above certain calcium concentrations, CA6 precipitated as a second phase at all sintering temperatures. The results also showed that abnormal grain growth can occur after precipitation and it is not only related to the calcium level, but it is also temperature dependent. In order to understand the formation mechanism of CA6 precipitates in calcium doped alumina samples, several studies have been carried out using either bulk materials or thin films The crystallization of CA2 and CA6 powders has been studied. Chemical processing techniques were used to synthesize the powders. It was observed that CA2 powders crystallized directly, however CA6 powders crystallized through gamma-Al 2O3 solid solution. The results of energy-loss near-edge spectrometry confirmed that gamma-Al2O3 can dissolve calcium. Calcium aluminate/alumina reaction couples have also been investigated. All reaction couples were heat treated following deposition. It was found that gamma-Al2O3 was formed at the interface as a result of the interfacial reaction between the film and the substrate. gamma-Al 2O3 at the interface was stable at much higher temperatures compared to the bulk gamma-Al2O3 formed prior to the CA6 crystallization. In order to

  10. Orion Capsule Handling Qualities for Atmospheric Entry

    Science.gov (United States)

    Tigges, Michael A.; Bihari, Brian D.; Stephens, John-Paul; Vos, Gordon A.; Bilimoria, Karl D.; Mueller, Eric R.; Law, Howard G.; Johnson, Wyatt; Bailey, Randall E.; Jackson, Bruce

    2011-01-01

    Two piloted simulations were conducted at NASA's Johnson Space Center using the Cooper-Harper scale to study the handling qualities of the Orion Command Module capsule during atmospheric entry flight. The simulations were conducted using high fidelity 6-DOF simulators for Lunar Return Skip Entry and International Space Station Return Direct Entry flight using bank angle steering commands generated by either the Primary (PredGuid) or Backup (PLM) guidance algorithms. For both evaluations, manual control of bank angle began after descending through Entry Interface into the atmosphere until drogue chutes deployment. Pilots were able to use defined bank management and reversal criteria to accurately track the bank angle commands, and stay within flight performance metrics of landing accuracy, g-loads, and propellant consumption, suggesting that the pilotability of Orion under manual control is both achievable and provides adequate trajectory performance with acceptable levels of pilot effort. Another significant result of these analyses is the applicability of flying a complex entry task under high speed entry flight conditions relevant to the next generation Multi Purpose Crew Vehicle return from Mars and Near Earth Objects.

  11. Astrocyte glycogenolysis is triggered by store-operated calcium entry and provides metabolic energy for cellular calcium homeostasis

    DEFF Research Database (Denmark)

    Müller, Margit S; Fox, Rebecca; Schousboe, Arne;

    2014-01-01

    Astrocytic glycogen, the only storage form of glucose in the brain, has been shown to play a fundamental role in supporting learning and memory, an effect achieved by providing metabolic support for neurons. We have examined the interplay between glycogenolysis and the bioenergetics of astrocytic...... cultures of murine cerebellar and cortical astrocytes, and determined glycogen content to investigate the effects of SOCE on glycogen metabolism. By blocking glycogenolysis, we tested energetic dependency of SOCE-related Ca(2+) dynamics on glycogenolytic ATP. Our results show that SOCE triggers astrocytic...... glycogenolysis. Upon inhibition of adenylate cyclase with 2',5'-dideoxyadenosine, glycogen content was no longer significantly different from that in unstimulated control cells, indicating that SOCE triggers astrocytic glycogenolysis in a cAMP-dependent manner. When glycogenolysis was inhibited in cortical...

  12. New low-cost MEMS capacitive pressure sensor concept

    Science.gov (United States)

    Wang, Yun; Cheung, Kin P.; Sheng, Kuang; Pai, Chien-Shing

    2005-01-01

    Capacitive pressure sensors based on surface or bulk MEMS technology have many attributes that make them highly desirable for many applications. The biggest technical challenge of capacitive pressure sensor technology is the creation of a reference cavity. It dictates the packaging approach and therefore the cost of the sensor. In this paper we introduce a new design of capacitive pressure sensor that takes advantage of a novel new wafer level packaging technology - A thin-film sealing technology that allows independent pressure control from high vacuum to high pressure. The new technology seals the vacuum cavity formed by standard surface micro machining technology by a brief melting of a metal layer using a pulsed laser. The ability to form reference vacuum cavity without the need for fusing or bonding with another structure allows the design to be simplified, leading to low cost and high yield.

  13. Noise and mismatch optimization for capacitive MEMS readout

    Institute of Scientific and Technical Information of China (English)

    Zhang Chong; Wu Qisong; Yin Tao; Yang Haigang

    2009-01-01

    This paper presents a high precision CMOS readout circuit for a capacitive MEMS gyroscope. A continuous time topology is employed as well as the chopper noise cancelling technique. A detailed analysis of the noise and mismatch of the capacitive readout circuit is given. The analysis and measurement results have shown that thermal noise dominates in the proposed circuit, and several approaches should be used for both noise and mismatch optimization. The circuit chip operates under a single 5 V supply, and has a measured capacitance resolution of 0.2 aF/√Hz. With such a readout circuit, the gyroscope can accurately measure the angular rate with a sensitivity of 15.3 mV/°/s.

  14. Last-passage Monte Carlo algorithm for mutual capacitance.

    Science.gov (United States)

    Hwang, Chi-Ok; Given, James A

    2006-08-01

    We develop and test the last-passage diffusion algorithm, a charge-based Monte Carlo algorithm, for the mutual capacitance of a system of conductors. The first-passage algorithm is highly efficient because it is charge based and incorporates importance sampling; it averages over the properties of Brownian paths that initiate outside the conductor and terminate on its surface. However, this algorithm does not seem to generalize to mutual capacitance problems. The last-passage algorithm, in a sense, is the time reversal of the first-passage algorithm; it involves averages over particles that initiate on an absorbing surface, leave that surface, and diffuse away to infinity. To validate this algorithm, we calculate the mutual capacitance matrix of the circular-disk parallel-plate capacitor and compare with the known numerical results. Good agreement is obtained.

  15. Effect of surfactants on capacitance properties of carbon electrodes

    International Nuclear Information System (INIS)

    Effect of surfactants present in alkaline solutions on the capacitance of carbon electrodes has been studied. Different types of surfactants, i.e., sodium and lithium dodecyl sulphate as anionic surfactants, tetrapropylammonium bromide and iodide as cationic surfactants and polymer of polyethylene glycol and p-t-octylophenol (commercially called Triton® X-100) as non-ionic one have been selected for this target. Concentration of these electrolyte additives was 0.005 mol L−1. Decreasing the surface tension in the electrode/electrolyte interface allows better penetration of electrolyte into the pores. However, surfactants played a different role depending on the electrode polarity. Detailed analysis of capacitance versus current load, frequency dependence as well as self-discharge, cyclability and behaviour in wider voltage range proved especially a profitable effect of Triton® X-100 on capacitor operating in alkaline solution. Influence of surfactant concentration on capacitance properties was also investigated.

  16. Low Power/Low Voltage Interface Circuitry for Capacitive Sensors

    DEFF Research Database (Denmark)

    Furst, Claus Efdmann

    This thesis focuses mainly on low power/low voltage interface circuits, implemented in CMOS, for capacitive sensors. A brief discussion of demands and possibilities for analog signal processing in the future is presented. Techniques for low power design is presented. This is done by analyzing power...... consumption of different amplifier topologies. Next, low power features of different amplifier types are analyzed on transistor level. A brief comparison of SI circuits for low power applications vs. SC circuits is presented. Methodologies for low voltage design is presented. This is followed by a collection...... power consumption. It is shown that the Sigma-Delta modulator is advantageous when embedded in a feedback loop with a mechanical sensor. Here a micro mechanical capacitive microphone. Feedback and detection circuitry for a capacitive microphone is presented. Practical implementations of low power...

  17. Intrinsic Low Hysteresis Touch Mode Capacitive Pressure Sensor

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio; Pedersen, Thomas; Hansen, Ole;

    2011-01-01

    Hysteresis has always been one of the main concerns when fabricating touch mode capacitive pressure sensors (TMCPS). This phenomenon can be fought at two different levels: during fabrication or after fabrication with the aid of a dedicated signal conditioning circuit. We will describe a microfabr......Hysteresis has always been one of the main concerns when fabricating touch mode capacitive pressure sensors (TMCPS). This phenomenon can be fought at two different levels: during fabrication or after fabrication with the aid of a dedicated signal conditioning circuit. We will describe...... a microfabrication step that can be introduced in order to reduce drastically the hysteresis of this type of sensors without compromising their sensitivity. Medium-high range (0 to 10 bar absolute pressure) TMCPS with a capacitive signal span of over 100pF and less than 1 % hysteresis in the entire pressure range...

  18. On Machine Capacitance Dimensional and Surface Profile Measurement System

    Science.gov (United States)

    Resnick, Ralph

    1993-01-01

    A program was awarded under the Air Force Machine Tool Sensor Improvements Program Research and Development Announcement to develop and demonstrate the use of a Capacitance Sensor System including Capacitive Non-Contact Analog Probe and a Capacitive Array Dimensional Measurement System to check the dimensions of complex shapes and contours on a machine tool or in an automated inspection cell. The manufacturing of complex shapes and contours and the subsequent verification of those manufactured shapes is fundamental and widespread throughout industry. The critical profile of a gear tooth; the overall shape of a graphite EDM electrode; the contour of a turbine blade in a jet engine; and countless other components in varied applications possess complex shapes that require detailed and complex inspection procedures. Current inspection methods for complex shapes and contours are expensive, time-consuming, and labor intensive.

  19. Noise and mismatch optimization for capacitive MEMS readout

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Chong; Wu Qisong; Yin Tao; Yang Haigang, E-mail: yanghg@mail.ie.ac.c [Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China)

    2009-11-15

    This paper presents a high precision CMOS readout circuit for a capacitive MEMS gyroscope. A continuous time topology is employed as well as the chopper noise cancelling technique. A detailed analysis of the noise and mismatch of the capacitive readout circuit is given. The analysis and measurement results have shown that thermal noise dominates in the proposed circuit, and several approaches should be used for both noise and mismatch optimization. The circuit chip operates under a single 5 V supply, and has a measured capacitance resolution of 0.2 aF/sq rootHz. With such a readout circuit, the gyroscope can accurately measure the angular rate with a sensitivity of 15.3 mV/{sup 0}/s. (semiconductor integrated circuits)

  20. Quantum Capacitance Modifies Interionic Interactions in Semiconducting Nanopores

    CERN Document Server

    Lee, Alpha A; Goriely, Alain

    2016-01-01

    Nanopores made with low dimensional semiconducting materials, such as carbon nanotubes and graphene slit pores, are used in supercapacitors. In theories and simulations of their operation, it is often assumed that such pores screen ion-ion interactions like metallic pores, i.e. that screening leads to an exponential decay of the interaction potential with ion separation. By introducing a quantum capacitance that accounts for the density of states in the material, we show that ion-ion interactions in carbon nanotubes and graphene slit pores actually decay algebraically with ion separation. This result suggests a new avenue of capacitance optimization based on tuning the electronic structure of a pore: a marked enhancement in capacitance might be achieved by developing nanopores made with metallic materials or bulk semimetallic materials.

  1. Capacitive measurement of mercury column heights in capillaries.

    Science.gov (United States)

    Frey, Sarah; Richert, Ranko

    2010-03-01

    The detection of changes in volume, e.g., in expansivity or aging measurements, are often translated into mercury column height within a glass capillary. We propose a capacitive technique for measuring the meniscus position using a cylindrical capacitor with mercury as the inner electrode, the capillary material as the dielectric, and a metal coat covering the outside surface of the capillary as the second electrode. The measured capacitance changes linearly with meniscus height, as long as the top mercury level remains within the range of the outer electrode. With the demonstrated noise level of 48 nm for our preliminary setup, meniscus height changes beyond 100 nm can be observed via the capacitance. PMID:20370203

  2. Wavelet approach to artifact noise removal from Capacitive coupled Electrocardiograph.

    Science.gov (United States)

    Lee, Seung Min; Kim, Ko Keun; Park, Kwang Suk

    2008-01-01

    Capacitive coupled Electrocardiography (ECG) is introduced as non-invasive measurement technology for ubiquitous health care and appliance are spread out widely. Although it has many merits, however, capacitive coupled ECG is very weak for motion artifacts for its non-skin-contact property. There are many studies for artifact problems which treats all artifact signals below 0.8Hz. In our capacitive coupled ECG measurement system, artifacts exist not only below 0.8Hz but also over than 10Hz. Therefore, artifact noise removal algorithm using wavelet method is tested to reject artifact-wandered signal from measured signals. It is observed that using power calculation each decimation step, artifact-wandered signal is removed as low frequency artifacts as high frequency artifacts. Although some original ECG signal is removed with artifact signal, we could level the signal quality for long term measure which shows the best quality ECG signals as we can get. PMID:19163323

  3. Penicillamine prevents ram sperm agglutination in media that support capacitation.

    Science.gov (United States)

    Leahy, T; Rickard, J P; Aitken, R J; de Graaf, S P

    2016-02-01

    Ram spermatozoa are difficult to capacitate in vitro. Here we describe a further complication, the unreported phenomenon of head-to-head agglutination of ram spermatozoa following dilution in the capacitation medium Tyrodes plus albumin, lactate and pyruvate (TALP). Sperm agglutination is immediate, specific and persistent and is not associated with a loss of motility. Agglutination impedes in vitro sperm handling and analysis. So the objectives of this study were to investigate the cause of sperm agglutination and potential agents which may reduce agglutination. The percentage of non-agglutinated, motile spermatozoa increased when bicarbonate was omitted from complete TALP suggesting that bicarbonate ions stimulate the agglutination process. d-penicillamine (PEN), a nucleophilic thiol, was highly effective at reducing agglutination. The inclusion of 250 μM PEN in TALP reduced the incidence of motile, agglutinated spermatozoa from 76.7 ± 2.7% to 2.8 ± 1.4%. It was then assessed if PEN (1 mM) could be included in existing ram sperm capacitation protocols (TALP +1 mM dibutyryl cAMP, caffeine and theophylline) to produce spermatozoa that were simultaneously capacitated and non-agglutinated. This protocol resulted in a sperm population which displayed high levels of tyrosine phosphorylated proteins and lipid disordered membranes (merocyanine-540) while remaining motile, viable, acrosome-intact and non-agglutinated. In summary, PEN (1 mM) can be included in ram sperm capacitation protocols to reduce sperm agglutination and allow for the in vitro assessment of ram sperm capacitation.

  4. Mitochondrial response and calcium ion change in apoptotic insect cells induced by SfaMNPV

    Institute of Scientific and Technical Information of China (English)

    XIU Meihong; PENG Jianxin; HONG Huazhu

    2005-01-01

    Mitochondrial responses and changes of calcium ions in apoptotic insect SL-1 cells induced by Syngrapha falcifera multiple nuclear polyhedrosis virus (SfaMNPV) are reported in this paper. By using Rhodamine 123 as a fluorescent labeling probe, flow cytometry analysis and confocal laser scanning microscope observation we observed that the mitochondrial transmembrane potential (△Ψm) began to decrease in SL-1 cells at 4 h post infection and △Ψm reduced continuously with the extension of virus infection. Western blotting indicated that the Bcl-2 level in the mitochondria gradually declined and was down- regulated. Cells undergoing apoptosis were found to have an elevation of cytochrome c in the cytosol and a corresponding decrease in the mitochondria, which indicated that cytochrome c was released from mitochondria into cytosol. These results suggest that mitochondrion-mediated apoptotic signal transduction pathway exists in apoptotic insect cell induced by SfaMNPV. Cytosolic free calcium ([Ca2+]i) concentration rapidly increased after SfaMNPV infection and the elevated calcium was tested to come partly from extracelllular calcium ion influx. Flow cytometry analysis indicated that the apoptosis in SL-1 cells was not influenced by established cytosolic calcium clamped conditions and the EGTA inhibiting calcium influx. Therefore, neither the elevation of cytosolic calcium ion nor extracellular calcium entry was the inducing factor of apoptosis, which hinted that the depletion of ER Ca2+ store contributed to SL-1 cell apoptosis induced by SfaMNPV.

  5. Wnt-induced calcium signaling mediates axon growth and guidance in the developing corpus callosum.

    Science.gov (United States)

    Hutchins, B Ian; Li, Li; Kalil, Katherine

    2012-01-10

    Wnt5a gradients guide callosal axons by repulsion through Ryk receptors in vivo. We recently found that Wnt5a repels cortical axons and promotes axon outgrowth through calcium signaling in vitro. Here, using cortical slices, we show that Wnt5a signals through Ryk to guide and promote outgrowth of callosal axons after they cross the midline. Calcium transient frequencies in callosal growth cones positively correlate with axon outgrowth rates in vitro. In cortical slices, calcium release through inositol 1,4,5-trisphosphate (IP(3)) receptors and calcium entry through transient receptor potential channels modulate axon growth and guidance. Knocking down Ryk inhibits calcium signaling in cortical axons, reduces rates of axon outgrowth subsequent to midline crossing, and causes axon guidance defects. Calcium- and calmodulin-dependent protein kinase II (CaMKII) is required downstream of Wnt-induced calcium signaling for postcrossing callosal axon growth and guidance. Taken together, these results suggest that growth and guidance of postcrossing callosal axons by Wnt-Ryk-calcium signaling involves axon repulsion through CaMKII.

  6. Capacitive Touch User Interface and Implementation with Virtual Refrigerator

    Directory of Open Access Journals (Sweden)

    MIT Academy of Engineering Global Technology and Engineering centre, Whirlpool of India

    2014-05-01

    Full Text Available The proposed User Interface incorporates 14 Touch keys, including slider and wheeler functionality using self capacitance technology, 24 side throw LED with intensity controlled Fade-IN, Fade-OUT effects, Buzzer chime, Voltage regulator circuit, and communication circuitry for the control board. The major advantage that this User Interface is that the entire assembly is less than 10mm thick including PCB, components, light guide and graphics sticker. In this project the mentioned capacitive touch user Interface is interfaced with a Lab view system simulating a virtual refrigerator capable of responding to the commands from the User Interface.

  7. Scanning Capacitance Microscopy in the Quantum Hall Regime

    OpenAIRE

    Suddards, Matthew Edmund

    2007-01-01

    This thesis discusses the development of a novel scanning capacitance microscope (SCM) that enables the investigation of the local capacitance and conductivity of surfaces and near-surface nanostructures at cryogenic temperatures and high magnetic fields. Simultaneous atomic force microscopy (AFM) and SCM measurements can be made at a temperature of 1.5K and a magnetic field of 12T. The AFM/SCM sensor is based on a quartz-tuning fork with an etched metal tip. SCM measurements are made us...

  8. The modelling of a capacitive microsensor for biosensing applications

    Science.gov (United States)

    Bezuidenhout, P. H.; Schoeman, J.; Joubert, T. H.

    2014-06-01

    Microsensing is a leading field in technology due to its wide application potential, not only in bio-engineering, but in other fields as well. Microsensors have potentially low-cost manufacturing processes, while a single device type can have various uses, and this consequently helps with the ever-growing need to provide better health conditions in rural parts of the world. Capacitive biosensors detect a change in permittivity (or dielectric constant) of a biological material, usually within a parallel plate capacitor structure which is often implemented with integrated electrodes of an inert metal such as gold or platinum on a microfluidic substrate typically with high dielectric constant. There exist parasitic capacitance components in these capacitive sensors, which have large influence on the capacitive measurement. Therefore, they should be considered for the development of sensitive and accurate sensing devices. An analytical model of a capacitive sensor device is discussed, which accounts for these parasitic factors. The model is validated with a laboratory device of fixed geometry, consisting of two parallel gold electrodes on an alumina (Al2O3) substrate mounted on a glass microscope slide, and with a windowed cover layer of poly-dimethyl-siloxane (PDMS). The thickness of the gold layer is 1μm and the electrode spacing is 300μm. The alumina substrate has a thickness of 200μm, and the high relative permittivity of 11.5 is expected to be a significantly contributing factor to the total device capacitance. The 155μm thick PDMS layer is also expected to contribute substantially to the total device capacitance since the relative permittivity for PDMS is 2.7. The wideband impedance analyser evaluation of the laboratory device gives a measurement result of 2pF, which coincides with the model results; while the handheld RLC meter readout of 4pF at a frequency of 10kHz is acceptable within the measurement accuracy of the instrument. This validated model will

  9. Double-driven shield capacitive type proximity sensor

    Science.gov (United States)

    Vranish, John M. (Inventor)

    1993-01-01

    A capacity type proximity sensor comprised of a capacitance type sensor, a capacitance type reference, and two independent and mutually opposing driven shields respectively adjacent to the sensor and reference and which are coupled in an electrical bridge circuit configuration and driven by a single frequency crystal controlled oscillator is presented. The bridge circuit additionally includes a pair of fixed electrical impedance elements which form adjacent arms of the bridge and which comprise either a pair of precision resistances or capacitors. Detection of bridge unbalance provides an indication of the mutual proximity between an object and the sensor. Drift compensation is also utilized to improve performance and thus increase sensor range and sensitivity.

  10. A low-noise/low-power preamplifier for capacitive microphones

    DEFF Research Database (Denmark)

    Fürst, Claus Erdmann

    1996-01-01

    A design for a microphone preamplifier for application in hearing aids is presented. The amplifier operates at a supply of 1-1.5 V, the current drain is 40 μA. The maximum sound level allowed is more than 120 dB SPL (Sound Pressure Level), with a typical noise level of 25 dB(A) SPL (A-weighted). ......-weighted). The amplifier is optimized for a capacitive microphone with a capacitance of 1.2 pF. The amplifier is fully integrated in a 0.7 μm n-well CMOS technology. Design details concerning noise performance are analytically described...

  11. Characterisation of a highly symmetrical miniature capacitive triaxial accelerometer

    OpenAIRE

    Lotters, J.C.; Olthuis, W.; Veltink, P.H.; Bergveld, P.

    1997-01-01

    A highly symmetrical cubic capacitive triaxial accelerometer for biomedical applications has been designed, realised and tested. The sensors are available in two outer dimensions, namely 2×2×2 and 5×5×5 mm3. The devices are mounted on a standard IC package for easy testing. Features of the sensor are a highly symmetrical cubic structure, capacitive coupling of the high frequency input voltage to the seismic mass and the use of the polymers polydimethylsiloxane (PDMS) as spring material betwee...

  12. Analysis of Capacitive Parasitism in PWM Inverter-Fed Motor

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effects of parasitic capacitance in induction motor system are unnoticed when it is fed from the AC line. but they are obvious when supplied directly from a PWM inverter. Consequently. many parasitic problems occur, such as motor-to-earth leakage current, bearing current, incoming line current distortion and uneven distribution of electrical stresses along the winding. On the ba sis of the uniform transmission line principle, a complete equivalent circuit of the PWM inverter-fed motor system is presented, based on which all the capacitive parasitic problems mentioned above are analyzed and simulated by means of PSPICE. All the results are consistent with the existing ones.

  13. [Impact of sperm capacitation on various populations of human spermatozoa].

    Science.gov (United States)

    Villanueva Díaz, C; Suárez Juárez, M; Díaz, M A; Ayala Ruiz, A

    1989-02-01

    With the purpose of evaluating the impact of spermatic capacitation on different spermatozooa populations, 49 samples of semen, before and after in vitro spermatic capacitation with Ham F-10 medium, were studied; motility of cells was evaluated according to WHO criteria. There was diminution of percentage of immobile cells, 27.8 to 20.0, as well as increase in population of cells with more mobility, 28.6% to 39.1%. Both difference were statistically significant (p = less than 0.05 and p = less than 0.005, respectively). These data suggest that spermatic capacitacion activates "in cascade" all groups of gametes. PMID:2486981

  14. Development of Image Reconstruction Algorithms in electrical Capacitance Tomography

    International Nuclear Information System (INIS)

    The Electrical Capacitance Tomography (ECT) has not obtained a good development in order to be used at industrial level. That is due first to difficulties in the measurement of very little capacitances (in the range of femto farads) and second to the problem of reconstruction on- line of the images. This problem is due also to the small numbers of electrodes (maximum 16), that made the usual algorithms of reconstruction has many errors. In this work it is described a new purely geometrical method that could be used for this purpose. (Author) 4 refs

  15. Nickel Oxide/Carbon Nanotubes Nanocomposite for Electrochemical Capacitance

    Institute of Scientific and Technical Information of China (English)

    Kui LIANG; Kayhyeok AN; Younghee LEE

    2005-01-01

    A nanocomposite of nickel oxide/carbon nanotubes was prepared through a simple chemical precipitation followed by thermal annealing. The electrochemical capacitance of this electrode material was studied. When the mass fraction of CNTs (carbon nanotubes) in NiO/CNT composites increases, the electrical resistivity of nanocomposites decreases and becomes similar to that of pure CNTs when it reaches 30%. The specific surface area of composites increases with increasing CNT mass fraction and the specific capacitance reaches 160 F/g under 10 mA/g discharge current density at CNT mass fraction of 10%.

  16. Differential capacitance probe for process control involving aqueous dielectric fluids

    Science.gov (United States)

    Svoboda, John M.; Morrison, John L.

    2002-10-08

    A differential capacitance probe device for process control involving aqueous dielectric fluids is disclosed. The device contains a pair of matched capacitor probes configured in parallel, one immersed in a sealed container of reference fluid, and the other immersed in the process fluid. The sealed container holding the reference fluid is also immersed in the process fluid, hence both probes are operated at the same temperature. Signal conditioning measures the difference in capacitance between the reference probe and the process probe. The resulting signal is a control error signal that can be used to control the process.

  17. Optimizing the Materials Response in Humidity Capacitive Sensors

    OpenAIRE

    Elham Noroozi Afshar; Hossein Golnabi; Nima E. Gorji

    2015-01-01

    The number of humidity outputs on the cap of a cylindrical capacitance sensor is optimized by designing three different probes with direct and indirect windows. The time interval is measured within which 30-70 % humidity can influence the dielectric constant and conductivity of the capacitance when exposed to a range of relative humidity. It is then compared with a simple set-up including a simplified equivalent circuit. The direct probes had four and double outputs on the window of the cylin...

  18. Flexible Capacitive Electrodes for Minimizing Motion Artifacts in Ambulatory Electrocardiograms

    Directory of Open Access Journals (Sweden)

    Jeong Su Lee

    2014-08-01

    Full Text Available This study proposes the use of flexible capacitive electrodes for reducing motion artifacts in a wearable electrocardiogram (ECG device. The capacitive electrodes have conductive foam on their surface, a shield, an optimal input bias resistor, and guarding feedback. The electrodes are integrated in a chest belt, and the acquired signals are transmitted wirelessly for ambulatory heart rate monitoring. We experimentally validated the electrode performance with subjects standing and walking on a treadmill at speeds of up to 7 km/h. The results confirmed the highly accurate heart rate detection capacity of the developed system and its feasibility for daily-life ECG monitoring.

  19. An Effective Hybrid Optimization Algorithm for Capacitated Vehicle Routing Problem

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Capacitated vehicle routing problem (CVRP) is an important combinatorial optimization problem. However, it is quite difficult to achieve an optimal solution with the traditional optimization methods owing to the high computational complexity. A hybrid algorithm was developed to solve the problem, in which an artificial immune clonal algorithm (AICA) makes use of the global search ability to search the optimal results and simulated annealing (SA) algorithm employs certain probability to avoid becoming trapped in a local optimum. The results obtained from the computational study show that the proposed algorithm is a feasible and effective method for capacitated vehicle routing problem.

  20. Store-operated calcium channels and pro-inflammatory signals

    Institute of Scientific and Technical Information of China (English)

    Wei-chiao CHANG

    2006-01-01

    In non-excitable cells such as T lymphocytes,hepatocytes,mast cells,endothelia and epithelia,the major pathway for calcium(Ca2+)entry is through store-operated Ca2+ channels in the plasma membrane.These channels are activated by the emptying of intracellular Ca2+ stores,however,neither the gating mechanism nor the downstream targets of these channels has been clear established.Here,I review some of the proposed gating mechanisms of store-operated Ca2+ channels and the functional implications in regulating pro-inflammatory signals.

  1. Effect of mitochondrial calcium uniporter blocking on human spermatozoa.

    Science.gov (United States)

    Bravo, A; Treulen, F; Uribe, P; Boguen, R; Felmer, R; Villegas, J V

    2015-08-01

    Calcium (Ca(2+) ) regulates a number of essential processes in spermatozoa. Ca(2+) is taken up by mitochondria via the mitochondrial calcium uniporter (mCU). Oxygen-bridged dinuclear ruthenium amine complex (Ru360) has been used to study mCU because it is a potent and specific inhibitor of this channel. In bovine spermatozoa, it has been demonstrated that mitochondrial calcium uptake inhibition adversely affects the capacitation process. It has been demonstrated in human spermatozoa that mCU blocking, through Ru360, prevents apoptosis; however, the contribution of the mCU to normal human sperm function has not been studied. Therefore, the aim of this study was to evaluate the effect of mCU blocking on human sperm function. Spermatozoa obtained from apparently healthy donors were incubated with 5 and 10 μm Ru360 for 4 h at 37 °C. Viability was assessed using propidium iodide staining; motility was determined by computer-aided sperm analysis, adenosine triphosphate (ATP) levels using a luminescence-based method, mitochondrial membrane potential (ΔΨm) using JC-1 staining and reactive oxygen species (ROS) production using dihydroethidium dye. Our results show that mCU blocking significantly reduced total sperm motility and ATP levels without affecting sperm viability, ΔΨm and ROS production. In conclusion, mCU contributes to the maintenance of sperm motility and ATP levels in human spermatozoa.

  2. 78 FR 38069 - Expansion of Global Entry to Additional Airports

    Science.gov (United States)

    2013-06-25

    ... Register on February 6, 2012 (77 FR 5681), promulgated the regulation to establish Global Entry as an... FR 17492.) Travelers who wish to participate in Global Entry must apply via the CBP Global Entry Web... SECURITY U.S. Customs and Border Protection Expansion of Global Entry to Additional Airports AGENCY:...

  3. Calcium signaling in taste cells.

    Science.gov (United States)

    Medler, Kathryn F

    2015-09-01

    The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.

  4. Individual aggregates of amyloid beta induce temporary calcium influx through the cell membrane of neuronal cells

    Science.gov (United States)

    Drews, Anna; Flint, Jennie; Shivji, Nadia; Jönsson, Peter; Wirthensohn, David; De Genst, Erwin; Vincke, Cécile; Muyldermans, Serge; Dobson, Chris; Klenerman, David

    2016-01-01

    Local delivery of amyloid beta oligomers from the tip of a nanopipette, controlled over the cell surface, has been used to deliver physiological picomolar oligomer concentrations to primary astrocytes or neurons. Calcium influx was observed when as few as 2000 oligomers were delivered to the cell surface. When the dosing of oligomers was stopped the intracellular calcium returned to basal levels or below. Calcium influx was prevented by the presence in the pipette of the extracellular chaperone clusterin, which is known to selectively bind oligomers, and by the presence a specific nanobody to amyloid beta. These data are consistent with individual oligomers larger than trimers inducing calcium entry as they cross the cell membrane, a result supported by imaging experiments in bilayers, and suggest that the initial molecular event that leads to neuronal damage does not involve any cellular receptors, in contrast to work performed at much higher oligomer concentrations. PMID:27553885

  5. [Progress in calcium regulation in myocardial and vascular ischemia-reperfusion injury].

    Science.gov (United States)

    He, Xi; Bi, Xue-Yuan; Wang, Hao; Yu, Xiao-Jiang; Zang, Wei-Jin

    2012-06-25

    Ischemia-reperfusion injury (IRI) has been recognized as a serious problem for therapy of cardiovascular diseases. Calcium regulation appears to be an important issue in the study of IRI. This article reviews calcium regulation in myocardial and vascular IRI, including the calcium overload and calcium sensitivity in IRI. This review is focused on the key players in Ca(2+) handling in IRI, including membrane damage resulting in increase in Ca(2+) influx, reverse-mode of Na(+)-Ca(2+) exchangers leading to increased Ca(2+) entry, the decreased activity of sarcoplasmic reticulum (SR) Ca(2+)-ATPase causing SR Ca(2+) uptake dysfunction, and increased activity of Rho kinase. These key players in Ca(2+) homeostasis will provide promising strategies and potential targets for therapy of cardiovascular IRI. PMID:22717637

  6. Fruit Calcium: Transport and Physiology

    Directory of Open Access Journals (Sweden)

    Bradleigh eHocking

    2016-04-01

    Full Text Available Calcium has well-documented roles in plant signaling, water relations and cell wall interactions. Significant research into how calcium impacts these individual processes in various tissues has been carried out; however, the influence of calcium on fruit ripening has not been thoroughly explored. Here, we review the current state of knowledge on how calcium may impact fruit development, physical traits and disease susceptibility through facilitating developmental and stress response signaling, stabilizing membranes, influencing water relations and modifying cell wall properties through cross-linking of de-esterified pectins. We explore the involvement of calcium in hormone signaling integral to ripening and the physiological mechanisms behind common disorders that have been associated with fruit calcium deficiency (e.g. blossom end rot in tomatoes or bitter pit in apples. This review works towards an improved understanding of how the many roles of calcium interact to influence fruit ripening, and proposes future research directions to fill knowledge gaps. Specifically, we focus mostly on grapes and present a model that integrates existing knowledge around these various functions of calcium in fruit, which provides a basis for understanding the physiological impacts of sub-optimal calcium nutrition in grapes. Calcium accumulation and distribution in fruit is shown to be highly dependent on water delivery and cell wall interactions in the apoplasm. Localized calcium deficiencies observed in particular species or varieties can result from differences in xylem morphology, fruit water relations and pectin composition, and can cause leaky membranes, irregular cell wall softening, impaired hormonal signaling and aberrant fruit development. We propose that the role of apoplasmic calcium-pectin crosslinking, particularly in the xylem, is an understudied area that may have a key influence on fruit water relations. Furthermore, we believe that improved

  7. DISTILLATION OF CALCIUM

    Science.gov (United States)

    Barton, J.

    1954-07-27

    This invention relates to an improvement in the process for the purification of caicium or magnesium containing an alkali metal as impurity, which comprises distiiling a batch of the mixture in two stages, the first stage distillation being carried out in the presence of an inert gas at an absolute pressure substantially greater than the vapor pressure of calcium or maguesium at the temperature of distillation, but less than the vaper pressure at that temperature of the alkali metal impurity so that only the alkali metal is vaporized and condensed on a condensing surface. A second stage distilso that substantially only the calcium or magnesium distills under its own vapor pressure only and condenses in solid form on a lower condensing surface.

  8. A silicon MEMS structure for characterization of femto-farad-level capacitive sensors with lock-in architecture

    OpenAIRE

    Wei, J; Chen, Z.L.; Liu, Z. W.; Sarro, P. M.

    2010-01-01

    This paper presents a silicon MEMS capacitive structure to investigate a test methodology for fF-level capacitive sensors’ measurement. The device mimics a capacitive sensor with a changing intermediate layer between the electrodes. A single mask bulk micromachining process is used to fabricate the device, which has a nominal capacitance of 1.2 fF. A high performance measurement setup based on lock-in principle is developed to detect the capacitance variation. The maximum capacitance variatio...

  9. 76 FR 66875 - Informal Entry Limit and Removal of a Formal Entry Requirement

    Science.gov (United States)

    2011-10-28

    ... quotas under the Agreement on Textiles and Clothing, CBP no longer needs to require formal entries for... for these articles due to the elimination of absolute quotas and visa requirements for textile..., which requires the use of a formal entry and visa or export license for certain shipments of textile...

  10. 77 FR 72715 - Informal Entry Limit and Removal of a Formal Entry Requirement

    Science.gov (United States)

    2012-12-06

    ... Agreement on Textiles and Clothing because CBP no longer needs to require formal entries for these articles... absolute quotas under the Agreement on Textiles and Clothing, CBP no longer needs to require formal entries... previously subject to absolute quotas under the Agreement on Textiles and Clothing. Comment: One...

  11. Atmospheric Entry Studies for Venus Missions: 45 Sphere-Cone Rigid Aeroshells and Ballistic Entries

    Science.gov (United States)

    Prabhu, Dinesh K.; Spilker, Thomas R.; Allen, Gary A., Jr.; Hwang, Helen H.; Cappuccio, Gelsomina; Moses, Robert W.

    2013-01-01

    The present study considers direct ballistic entries into the atmosphere of Venus using a 45deg sphere-cone rigid aeroshell, a legacy shape that has been used successfully in the past in the Pioneer Venus Multiprobe Mission. For a number of entry mass and heatshield diameter combinations (i.e., various ballistic coefficients) and entry velocities, the trajectory space in terms of entry flight path angles between skip out and -30deg is explored with a 3DoF trajectory code, TRAJ. From these trajectories, the viable entry flight path angle space is determined through the use of mechanical and thermal performance limits on the thermal protection material and science payload; the thermal protection material of choice is entry-grade carbon phenolic, for which a material thermal response model is available. For mechanical performance, a 200 g limit is placed on the peak deceleration load experienced by the science instruments, and 10 bar is assumed as the pressure limit for entry-grade carbon-phenolic material. For thermal performance, inflection points in the total heat load distribution are used as cut off criteria. Analysis of the results shows the existence of a range of critical ballistic coefficients beyond which the steepest possible entries are determined by the pressure limit of the material rather than the deceleration load limit.

  12. Virus and calcium: an unexpected tandem to optimize insecticide efficacy.

    Science.gov (United States)

    Apaire-Marchais, Véronique; Ogliastro, Mylène; Chandre, Fabrice; Pennetier, Cédric; Raymond, Valérie; Lapied, Bruno

    2016-04-01

    The effective control of insect pests is based on the rational use of the most efficient and safe insecticide treatments. To increase the effects of classical insecticides and to avoid the ability of certain pest insects to develop resistance, it is essential to propose novel strategies. Previous studies have shown that calcium-dependent phosphorylation/dephosphorylation is now considered as a new cellular mechanism for increasing the target sensitivity to insecticides. Because it is known that virus entry is correlated with intracellular calcium concentration rise, this report attempts to present the most important data relevant to the feasibility of combining an insect virus such as baculovirus or densovirus with an insecticide. In this case, the insect virus is not used as a bioinsecticide but acts as a synergistic agent able to trigger calcium rise and to activate calcium-dependent intracellular signalling pathways involved in the increase of the membrane receptors and/or ion channels sensitivity to insecticides. This virus-insecticide mixture represents a promising alternative to optimize the efficacy of insecticides against insect pests while reducing the doses. PMID:26743399

  13. Autonomous gliding entry guidance with geographic constraints

    Institute of Scientific and Technical Information of China (English)

    Guo Jie; Wu Xuzhong; Tang Shengjing

    2015-01-01

    This paper presents a novel three-dimensional autonomous entry guidance for relatively high lift-to-drag ratio vehicles satisfying geographic constraints and other path constraints. The guidance is composed of onboard trajectory planning and robust trajectory tracking. For trajectory planning, a longitudinal sub-planner is introduced to generate a feasible drag-versus-energy profile by using the interpolation between upper boundary and lower boundary of entry corridor to get the desired trajectory length. The associated magnitude of the bank angle can be specified by drag profile, while the sign of bank angle is determined by lateral sub-planner. Two-reverse mode is utilized to satisfy waypoint constraints and dynamic heading error corridor is utilized to satisfy no-fly zone constraints. The longitudinal and lateral sub-planners are iteratively employed until all of the path constraints are satisfied. For trajectory tracking, a novel tracking law based on the active disturbance rejection control is introduced. Finally, adaptability tests and Monte Carlo simulations of the entry guidance approach are performed. Results show that the proposed entry guidance approach can adapt to different entry missions and is able to make the vehicle reach the prescribed target point precisely in spite of geographic constraints.

  14. 1994 entry-level athletic training salaries.

    Science.gov (United States)

    Moss, C L

    1996-01-01

    In this study, I examined salaries for entry-level positions in athletic training during the year 1994. An entry-level position was defined as a position to be filled with an athletic trainer certified by the NATA, with no full-time paid employment experience. According to the "Placement Vacancy Notice" (NATA, Dallas, TX) and "BYLINE" (Athletic Trainer Services, Inc, Mt Pleasant, MI), there were 432 entry-level vacancies in hospital/clinics, college/universities, and high school settings. A total of 271 surveys (63%) were returned. Overall, beginning salaries for entry-level athletic training positions were $23,228 (+/-$3,177) for a bachelor's degree and $25,362 (+/-$3,883) for a master's degree. A stipend ($4,216 +/- $2,039) was included in 86% of the high school positions. The term of contract for high school was usually a 10-month position (10.0 +/- .9 months), hospital/clinic, 12-months (11.7 +/- .7 months), while the college/university varied from 9 to 12 months (10.5 +/- 1.2 months). Also included in the study was fringe benefit information: pension (other than Social Security), life, medical, dental, and vision insurance. Continued studies are recommended to establish salary norms and trends for entry-level positions so that athletic trainers will understand what monetary compensation to expect for their services. PMID:16558367

  15. Skip entry trajectory planning and guidance

    Science.gov (United States)

    Brunner, Christopher William

    A numerical predictor-corrector (NPC) method for trajectory planning and closed-loop guidance of low lift-to-drag (L/D) ratio vehicles during the skip entry phase of a lunar-return mission is presented. The strategy calls for controlling the trajectory by modulation of the magnitude of the vehicle's bank angle. The magnitude of the bank angle used in the skip phase is determined by satisfying the downrange requirement to the landing site. The problem is formulated as a nonlinear univariate root-finding problem. Full three degree of freedom (3DOF) nonlinear trajectory dynamics are included to achieve high accuracy of the landing prediction. In addition, the proposed approach automatically yields a direct entry trajectory when the downrange is such that a skip entry is no longer necessary. The same algorithm repeatedly applied on-board in every guidance cycle realizes closed-loop guidance in the skip entry phase. A number of issues are identified and addressed that are critical in closed-loop implementations. Extensive 3DOF dispersion simulations are performed to evaluate the performance of the proposed approach, and the results demonstrate very reliable and robust performance of the algorithm in highly stressful dispersed conditions. Comparison is made between the proposed algorithm and an earlier skip algorithm developed for the Apollo space program. It is shown that the proposed algorithm is superior to the Apollo algorithm especially when used for entries with long downranges.

  16. Water Desalination Using Capacitive Deionization with Microporous Carbon Electrodes

    NARCIS (Netherlands)

    Porada, S.; Weinstein, L.; Dash, R.; Wal, van der A.F.; Bryjak, M.; Gogotsi, Y.; Biesheuvel, P.M.

    2012-01-01

    Capacitive deionization (CDI) is a water desalination technology in which salt ions are removed from brackish water by flowing through a spacer channel with porous electrodes on each side. Upon applying a voltage difference between the two electrodes, cations move to and are accumulated in electrost

  17. Dynamic Adsorption/Desorption Process Model of Capacitive Deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Limpt, van B.; Wal, van der A.

    2009-01-01

    In capacitive deionization (CDI), an electrical potential difference is applied across oppositely placed electrodes, resulting in the adsorption of ions from aqueous solution and a partially ion-depleted product stream. CDI is a dynamic process which operates in a sequential mode; i.e., after a cert

  18. Performance analysis of a digital capacitance measuring circuit.

    Science.gov (United States)

    Xu, Lijun; Sun, Shijie; Cao, Zhang; Yang, Wuqiang

    2015-05-01

    This paper presents the design and study of a digital capacitance measuring circuit with theoretical analysis, numerical simulation, and experimental evaluation. The static and dynamic performances of the capacitance measuring circuit are first defined, including signal-to-noise ratio (SNR), standard deviation, accuracy, linearity, sensitivity, and response time, within a given measurement range. Then numerical simulation is carried out to analyze the SNR and standard deviation of the circuit, followed by experiments to validate the overall performance of the circuit. The simulation results show that when the standard deviation of noise is 0.08 mV and the measured capacitance decreases from 6 pF to 3 fF, the SNR decreases from 90 dB to 22 dB and the standard deviation is between 0.17 fF and 0.24 fF. The experimental results show that when the measured capacitance decreases from 6 pF to 40 fF and the data sampled in a single period are used for demodulation, the SNR decreases from 88 dB to 40 dB and the standard deviation is between 0.18 fF and 0.25 fF. The maximum absolute error and relative error are 5.12 fF and 1.26%, respectively. The SNR and standard deviation can be further improved if the data sampled in more than one period are used for demodulation by the circuit.

  19. High bandwidth on-chip capacitive tuning of microtoroid resonators.

    Science.gov (United States)

    Baker, Christopher G; Bekker, Christiaan; McAuslan, David L; Sheridan, Eoin; Bowen, Warwick P

    2016-09-01

    We report on the design, fabrication and characterization of silica microtoroid based cavity opto-electromechanical systems (COEMS). Electrodes patterned onto the microtoroid resonators allow for rapid capacitive tuning of the optical whispering gallery mode resonances while maintaining their ultrahigh quality factor, enabling applications such as efficient radio to optical frequency conversion, optical routing and switching applications. PMID:27607646

  20. Topology Optimization of Stressed Capacitive RF MEMS Switches

    DEFF Research Database (Denmark)

    Philippine, Mandy A.; Sigmund, Ole; Rebeiz, Gabriel M.;

    2013-01-01

    Geometry design can improve a capacitive radio-frequency microelectromechanical system switch's reliability by reducing the impacts of intrinsic biaxial stresses and stress gradients on the switch's membrane. Intrinsic biaxial stresses cause stress stiffening, whereas stress gradients cause out-o...

  1. RF-MEMS capacitive switches with high reliability

    Science.gov (United States)

    Goldsmith, Charles L.; Auciello, Orlando H.; Carlisle, John A.; Sampath, Suresh; Sumant, Anirudha V.; Carpick, Robert W.; Hwang, James; Mancini, Derrick C.; Gudeman, Chris

    2013-09-03

    A reliable long life RF-MEMS capacitive switch is provided with a dielectric layer comprising a "fast discharge diamond dielectric layer" and enabling rapid switch recovery, dielectric layer charging and discharging that is efficient and effective to enable RF-MEMS switch operation to greater than or equal to 100 billion cycles.

  2. Capacitive technology for energy extraction from chemical potential differences

    NARCIS (Netherlands)

    Bastos Sales, B.

    2013-01-01

    This thesis introduces the principle of Capacitive energy extraction based on Donnan Potential (CDP) to exploit salinity gradients. It also shows the fundamental characterization and improvements of CDP. An alternative application of this technology aimed at thermal gradients was tested.  

  3. Resistance identification and rational process design in Capacitive Deionization

    NARCIS (Netherlands)

    Dijkstra, J.E.; Zhao, R.; Biesheuvel, P.M.; Wal, van der A.

    2016-01-01

    Capacitive Deionization (CDI) is an electrochemical method for water desalination employing porous carbon electrodes. To enhance the performance of CDI, identification of electronic and ionic resistances in the CDI cell is important. In this work, we outline a method to identify these resistances. W

  4. Optimization of salt adsorption rate in membrane capacitive deionization

    NARCIS (Netherlands)

    Zhao, R.; Satpradit, O.A.; Rijnaarts, H.; Biesheuvel, P.M.; Wal, van der A.

    2013-01-01

    Membrane capacitive deionization (MCDI) is a water desalination technique based on applying a cell voltage between two oppositely placed porous electrodes sandwiching a spacer channel that transports the water to be desalinated. In MCDI, ion-exchange membranes are positioned in front of each porous

  5. An Approximation Algorithm for the Capacitated Arc Routing Problem

    DEFF Research Database (Denmark)

    Wøhlk, Sanne

    2008-01-01

    In this paper we consider approximation of the Capacitated Arc Routing Problem, which is the problem of servicing a set of edges in a graph using a fleet of capacity constrained vehicles. We present a 7/2 - 3/W-approximation algorithm for the problem and prove that this algorithm outperforms...

  6. Simple and economical capacitive displacement system for UHV operation.

    Science.gov (United States)

    Chow, R; Tiller, W A

    1979-12-01

    A parallel plate capacitor was assembled as a displacement transducer for operation in an UHV environment. The capacitive displacement system was linear over a 2.5 mum range with a resolution of 0.051 mum. Components in the electric circuit were common laboratory instruments.

  7. Probing 2D black phosphorus by quantum capacitance measurements.

    Science.gov (United States)

    Kuiri, Manabendra; Kumar, Chandan; Chakraborty, Biswanath; Gupta, Satyendra N; Naik, Mit H; Jain, Manish; Sood, A K; Das, Anindya

    2015-12-01

    Two-dimensional materials and their heterostructures have emerged as a new class of materials, not only for fundamental physics but also for electronic and optoelectronic applications. Black phosphorus (BP) is a relatively new addition to this class of materials. Its strong in-plane anisotropy makes BP a unique material for making conceptually new types of electronic devices. However, the global density of states (DOS) of BP in device geometry has not been measured experimentally. Here, we report the quantum capacitance measurements together with the conductance measurements on an hBN-protected few-layer BP (∼six layers) in a dual-gated field effect transistor (FET) geometry. The measured DOS from our quantum capacitance is compared with density functional theory (DFT). Our results reveal that the transport gap for quantum capacitance is smaller than that in conductance measurements due to the presence of localized states near the band edge. The presence of localized states is confirmed by the variable range hopping seen in our temperature dependence conductivity. A large asymmetry is observed between the electron and hole side. This asymmetric nature is attributed to the anisotropic band dispersion of BP. Our measurements establish the uniqueness of quantum capacitance in probing the localized states near the band edge, hitherto not seen in conductance measurements. PMID:26559656

  8. Quantum superposition of charge states on capacitively coupled superconducting islands

    NARCIS (Netherlands)

    Heij, C.P.; Dixon, D.C.; Wal, C.H. van der; Hadley, P.; Mooij, J.E.

    2003-01-01

    We investigate the ground state properties of a system containing two superconducting islands coupled capacitively by a wire. The ground state is a macroscopic superposition of charge states, even though the islands cannot exchange charge carriers. The ground state of the system is probed by measuri

  9. A High-Precision Capacitive Sensor System for Displacement Measurements

    NARCIS (Netherlands)

    Yang, R.

    2015-01-01

    This thesis presents the theory, design and qualification of a precision capacitive sensor system for displacement measurement that require high resolution, high precision and simultaneously, low power consumption. The challenge to achieve the required performance has been taken care at both mechani

  10. Reconfigurable Prototyping Microfluidic Platform for DEP Manipulation and Capacitive Sensing.

    Science.gov (United States)

    Miled, Amine; Auclair, Benoit; Srasra, Anis; Sawan, Mohamad

    2015-04-01

    In this paper, we present a new rapid prototyping platform dedicated to dielectrophoretic microfluidic manipulation and capacitive cell sensing. The proposed platform offers a reconfigurable design including 4 independently programmable output channels to be distributed across 64 electrodes. Although its range of frequency covers up to 3.4 MHz, signal amplitude accuracy ( +/-10%) was demonstrated for frequencies up to 1 MHz and channel-to-channel phase shift setting was stable up to 1.5 MHz. A test of maximum resistive load showed a 10% attenuation of a 12 V peak-to-peak signal with a 22 Ω load. The platform has an advanced capacitive sensor to measure capacitance variation between in-channel electrodes with a sampling frequency up to 5 kH z. Experimental data of capacitive sensor showed a sensitivity of 100 fF. The sensor can be extended to 4 parallel measurements with lower frequency. We also present a new assembly technique for reusable microfluidic chip based on anisotropic adhesive conductive film, epoxy and PDMS. The proposed platform provides a wide range of control signals depending on the type of manipulation as sine, rectangular or square wave. The frequency range is extendible up to 3.4 MHz, in addition to a programmable phase shift circuit with a minimum phase step of 3.6(°) for each signal. PMID:25879968

  11. Capacitive sensor probe to assess frying oil degradation

    Directory of Open Access Journals (Sweden)

    Alfadhl Yahya Khaled

    2015-09-01

    Full Text Available The repeated usage of frying oil has been proven hazardous due to the degradation process by chemical reactions that lead to changes in the quality of the oil. Currently, the degree of frying oil degradation is indicated by the percentage of its total polar compounds (TPC. In this study, a capacitive sensor was designed to assess frying oil degradation at several heating time intervals by measuring changes on its electrical capacitance. The sensor was designed using interdigitated electrode structure. A total of 30 samples of 130 ml palm oil were heated at 180 °C up to 30 h. For each one hour interval, one sample was moved out from the laboratory oven. The electrical capacitance, total polar compound (TPC and viscosity of the samples were measured for analysis. Preliminary results demonstrated significant correlation between oil electrical capacitance with TPC and viscosity with R2 ranged from 0.83 to 0.90. The designed sensor has good potential for simple and inexpensive way of determining frying oil quality.

  12. Stray capacitances in the watt balance operation: electrostatic forces

    DEFF Research Database (Denmark)

    Quagliotti, Danilo; Mana, G.

    2014-01-01

    In a watt balance, stray capacitances exist between the coil and the magnet. Since the electric current flowing in the coil creates a difference in electric potentials between the coil and magnet, their electrostatic interactions must be taken into account. This paper reports the results of a...

  13. A Micro Dynamically Tuned Gyroscope with Adjustable Static Capacitance

    Directory of Open Access Journals (Sweden)

    Lun Kong

    2013-02-01

    Full Text Available This paper presents a novel micro dynamically tuned gyroscope (MDTG with adjustable static capacitance. First, the principle of MDTG is theoretically analyzed. Next, some simulations under the optimized structure parameters are given as a reference for the mask design of the rotor wafer and electrode plates. As two key components, the process flows of the rotor wafer and electrode plates are described in detail. All the scanning electron microscopy (SEM photos show that the fabrication process is effective and optimized. Then, an assembly model is designed for the static capacitance adjustable MDTG, whose static capacitance can be changed by rotating the lower electrode plate support and substituting gasket rings of different thicknesses. Thus, the scale factor is easily changeable. Afterwards, the digitalized closed-loop measurement circuit is simulated. The discrete correction and decoupling modules are designed to make the closed-loop stable and cross-coupling effect small. The dual axis closed-loop system bandwidths can reach more than 60 Hz and the dual axis scale factors are completely symmetrical. All the simulation results demonstrate the proposed fabrication of the MDTG can meet the application requirements. Finally, the paper presents the test results of static and dynamic capacitance values which are consistent with the simulation values.

  14. Rapid Prototyping of Tangibles with a Capacitive Mouse

    DEFF Research Database (Denmark)

    Ramos, Juan David Hincapie; Esbensen, Morten; Kogutowska, Magdalena

    2011-01-01

    lays the capacitive surface and communication capa- bilities of a Microsoft TouchMouse, both of which are ap- propriated to fulfill the mentined requirements. Unlike ex- isting approaches for rapid prototyping of tangibles like the Arduino boards, using the Toki toolkit does not require de- velopers...

  15. Carbon nanotube yarns as strong flexible conductive capacitive electrodes

    NARCIS (Netherlands)

    Liu, F.; Wagterveld, R.M.; Gebben, B.; Otto, M.J.; Biesheuvel, P.M.; Hamelers, H.V.M.

    2015-01-01

    Carbon nanotube (CNT) yarn, consisting of 23 µm diameter CNT filaments, can be used as capacitive electrodes that are long, flexible, conductive and strong, for applications in energy and electrochemical water treatment. We measure the charge storage capacity as function of salt concentration, and u

  16. Energy consumption and constant current operation in membrane capacitive deionization

    NARCIS (Netherlands)

    Zhao, R.; Biesheuvel, P.M.; Wal, van der A.F.

    2012-01-01

    Membrane capacitive deionization (MCDI) is a water desalination technology based on applying a cell voltage between two oppositely placed porous electrodes sandwiching a spacer channel that transports the water to be desalinated. In the salt removal step, ions are adsorbed at the carbon–water interf

  17. MEMS Very Low Capacitive Pressure Sensor Based on CMOS Process

    International Nuclear Information System (INIS)

    The CMOS standard process with advantage of simplicity in term of design and fabrication process compatibility has triggered the invention of MEMS very low capacitive pressure sensor, (MEMS-VLCPS). In this paper the development of the whole structure of MEMS-VLCPS that involves the design simulation, fabrication and testing is described. The novelty of this work lies in the design and fabrication process itself. A new technique in fabricating thin sensor membrane of VLCPS using seal-off techniques is also presented. The physical structure of the membrane consists of parallel plate. The top plate acts as the flexible electrode membrane and the bottom plate acts as the counter electrode membrane. Both plates are separated by absolute air gap with fixed end at both sides. As a result, it was found that the etch-opening holes of 0.8 μm and seal-off thickness of 4000 Angstrom gave the optimum sealing surface. The percentage of relative capacitance change is extracted from the reference capacitance measurement. Air gap thickness of 0.3 μm gives the highest percentage of PRCC showing that smaller air gap thickness provides a larger change in capacitance value. (author)

  18. Mesoporous carbon microspheres with high capacitive performances for supercapacitors

    International Nuclear Information System (INIS)

    Highlights: • Small mesopores-enriched porous carbon microspheres were easily synthesized. • Small mesopores offer high ion-accessible surface area and facilitated ion diffusion. • The porous carbon exhibited a high specific capacitance and a good power property. - Abstract: Novel small-mesopores-enriched porous carbon microspheres have been synthesized from carbonaceous polysaccharide microspheres, by using the associated lithium acetate treating and heat treating strategies. X-ray diffraction, scanning electron microscope, transmission electron microscopy and nitrogen adsorption-desorption techniques have been employed to investigate the as-prepared samples. The analysis results indicate that the porous carbon microspheres has a high specific surface area of 1163 m2 g−1 and a satisfactory small mesoporous texture (2∼5 nm), with the mean pore size of 3.24 nm and the pore volume ratio of 2∼5 nm pores up to 92%. The capacitive performances of the samples in 6 mol L−1 KOH aqueous electrolyte, have been tested by cyclic voltammetry, electrochemical impedance spectroscopy and charge-discharge techniques. A specific capacitance of 171.5 F/g is obtained for the porous carbon microspheres via charge-discharge at a current density of 1000 mA/g. It also displayed a very high cycle stability of 97.8%, compared with the initial capacitance, after 1000 cycles at the high current density of 1000 mA/g

  19. Miniature electrometer preamplifier effectively compensates for input capacitance

    Science.gov (United States)

    Burrous, C. N.; Deboo, G. J.

    1966-01-01

    Negative capacitance preamplifier using a dual MOS /Metal Oxide Silicon/ transistor in conjunction with bipolar transistors is used with intracellular microelectrodes in recording bioelectric potentials. Applications would include use as a pickup plate video amplifier in storage tube tests and for pH and ionization chamber measurements.

  20. High bandwidth on-chip capacitive tuning of microtoroid resonators

    CERN Document Server

    Baker, Christopher G; McAuslan, David L; Sheridan, Eoin; Bowen, Warwick P

    2016-01-01

    We report on the design, fabrication and characterization of silica microtoroid based cavity opto-electromechanical systems (COEMS). Electrodes patterned onto the microtoroid resonators allow for rapid capacitive tuning of the optical whispering gallery mode resonances while maintaining their ultrahigh quality factor, enabling applications such as efficient radio to optical frequency conversion, optical routing and switching applications.

  1. An integrated energy-efficient capacitive sensor digital interface circuit

    KAUST Repository

    Omran, Hesham

    2014-06-19

    In this paper, we propose an energy-efficient 13-bit capacitive sensor interface circuit. The proposed design fully relies on successive approximation algorithm, which eliminates the need for oversampling and digital decimation filtering, and thus low-power consumption is achieved. The proposed architecture employs a charge amplifier stage to acheive parasitic insensitive operation and fine absolute resolution. Moreover, the output code is not affected by offset voltages or charge injection. The successive approximation algorithm is implemented in the capacitance-domain using a coarse-fine programmable capacitor array, which allows digitizing wide capacitance range in compact area. Analysis for the maximum achievable resolution due to mismatch is provided. The proposed design is insensitive to any reference voltage or current which translates to low temperature sensitivity. The operation of a prototype fabricated in a standard CMOS technology is experimentally verified using both on-chip and off-chip capacitive sensors. Compared to similar prior work, the fabricated prototype achieves and excellent energy efficiency of 34 pJ/step.

  2. Capacitive pressure sensor in post-processing on LTCC substrates

    NARCIS (Netherlands)

    Meijerink, M.G.H.; Nieuwkoop, E.; Veninga, E.P.; Meuwissen, M.H.H.; Tijdink, M.W.W.J.

    2005-01-01

    A capacitive pressure sensor was realized by means of a post-processing step on a low temperature co-fired ceramics (LTCC) substrate. The new sensor fabrication technology allows for integration of the sensor with interface circuitry and possibly also wireless transmission circuits on LTCC substrate

  3. Capacitive deionization on-chip; desalination of small volume samples

    NARCIS (Netherlands)

    Roelofs, S.H.; Rooijen, van M.; Kim, B.; Han, J.; Berg, van den A.; Odijk, M.

    2014-01-01

    This abstract demonstrates, for the first time, capacitive deionization (CDI) inside a chip measured using impedance spectroscopy [1]. CDI is a promising technique for the pre-treatment of extremely small volume protein samples (nL range) before analysis by mass spectroscopy [2]. The results include

  4. Multilevel inverter based class D audio amplifier for capacitive transducers

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    The reduced semiconductor voltage stress makes the multilevel inverters especially interesting, when driving capacitive transducers for audio applications. A ± 300 V flying capacitor class D audio amplifier driving a 100 nF load in the midrange region of 0.1-3.5 kHz with Total Harmonic Distortion...

  5. A Low-Cost Universal Integrated Interface for Capacitive Sensors

    NARCIS (Netherlands)

    Heidary, A.

    2010-01-01

    This thesis reports the results of research on features, options and limitations of low-cost, high-performance, universal integrated interface for capacitive sensors. It concerns development-driven research, where the objectives of the research focus upon possible realization and application of the

  6. Models of calcium signalling

    CERN Document Server

    Dupont, Geneviève; Kirk, Vivien; Sneyd, James

    2016-01-01

    This book discusses the ways in which mathematical, computational, and modelling methods can be used to help understand the dynamics of intracellular calcium. The concentration of free intracellular calcium is vital for controlling a wide range of cellular processes, and is thus of great physiological importance. However, because of the complex ways in which the calcium concentration varies, it is also of great mathematical interest.This book presents the general modelling theory as well as a large number of specific case examples, to show how mathematical modelling can interact with experimental approaches, in an interdisciplinary and multifaceted approach to the study of an important physiological control mechanism. Geneviève Dupont is FNRS Research Director at the Unit of Theoretical Chronobiology of the Université Libre de Bruxelles;Martin Falcke is head of the Mathematical Cell Physiology group at the Max Delbrück Center for Molecular Medicine, Berlin;Vivien Kirk is an Associate Professor in the Depar...

  7. Deep-Hole Inner Diameter Measuring System Based on Non-contact Capacitance Sensor

    Institute of Scientific and Technical Information of China (English)

    于永新; 张恒; 王宗超; 常以哲

    2010-01-01

    A precise aperture measuring system of small deep holes with capacitance sensors is presented. Based on the working principle of non-contact capacitance sensors, influence of the edge effect of gauge head is studied, and one capacitance sensor for measuring the aperture of the small blind holes or through holes is introduced. The system is composed of one positioning device, one aperture measuring capacitance sensor, one measuring circuit, and software. This system employs visual CCD and two-dimensional mic...

  8. Characterization and Modeling of Subfemtofarad Nanowire Capacitance Using the CBCM Technique

    OpenAIRE

    Zhao, Hui; Kim, Raseong; Paul, Abhijeet; Luisier, Mathieu; Klimeck, Gerhard; Ma, Fa-Jun; Rustagi, Subhash; Ganesh S. Samudra; Singh, Navab; Lo, Guo-Qiang; Kwong, Dim-Lee

    2009-01-01

    The experimental characterization of gate capacitance in nanoscale devices is challenging. We report an application of the charge-based capacitance measurement (CBCM) technique to measure the gate capacitance of a single-channel nanowire transistor. The measurement results are validated by 3-D electrostatic computations for parasitic estimation and 2-D self-consistent sp(3)s*d5 tight-binding computations for intrinsic gate capacitance calculations. The device simulation domains were construct...

  9. Characterization and Modeling of Subfemotofarad Nanowire Capacitance Using the CBCM Technique

    OpenAIRE

    Zhao, Hui; Kim, Raseong; Paul, Abhijeet; Luisier, Mathieu; Klimeck, Gerhard; Ma, Fa-Jun; Rustagi, Subhash C.; Ganesh S. Samudra; Singh, Navab; Lo, Guo-Qiang; Kwong, Dim-Lee

    2009-01-01

    The experimental characterization of gate capacitance in nanoscale devices is challenging. We report an application of the charge-based capacitance measurement (CBCM) technique to measure the gate capacitance of a single-channel nanowire transistor. The measurement results are validated by 3-D electrostatic computations for parasitic estimation and 2-D self-consistent sp3s∗d5 tight-binding computations for intrinsic gate capacitance calculations. The device simulation domains were constructed...

  10. On the capacitance of crystalline silicon solar cells in steady state

    OpenAIRE

    BARRO, FABE IDRISSA; SANE, Moustapha; ZOUMA, BERNARD

    2015-01-01

    In this work, an analytical approach is presented for modeling the capacitance of crystalline silicon solar cells. Based on a one-dimensional modeling of the cell, the excess minority carrier density, the photovoltage, and the capacitance are calculated. The motivation of this work are two-fold: to show base doping density and illumination effects on the capacitance of silicon solar cells, and to propose a determination technique for both dark capacitance and base doping density f...

  11. Theory of volumetric capacitance of an electric double-layer supercapacitor

    OpenAIRE

    Skinner, Brian; Chen, Tianran; Loth, M. S.; Shklovskii, B. I.

    2011-01-01

    Electric double layer supercapacitors are a fast-rising class of high-power energy storage devices based on porous electrodes immersed in a concentrated electrolyte or ionic liquid. As of yet there is no microscopic theory to describe their surprisingly large capacitance per unit volume (volumetric capacitance) of ~ 100 F/cm^3, nor is there a good understanding of the fundamental limits on volumetric capacitance. In this paper we present a non-mean-field theory of the volumetric capacitance o...

  12. Electrode Polarization in Glassy Electrolytes: Large Interfacial Capacitance Values and Indication for Pseudocapacitive Charge Storage

    OpenAIRE

    Mariappan, C. R.; Heins, T. P.; Roling, B.

    2009-01-01

    We study the electrode polarization behaviour of different Na-Ca-phosphosilicate glasses by measuring the differential capacitance between blocking Pt electrodes. At low applied dc bias voltages, we detect a linear capacitance regime with interfacial capacitance values considerably larger than expected from double layer theories and also considerably larger than found for ionic liquids with similar ion concentrations. With increasing bias voltages, the differential capacitance of interfacial ...

  13. Corrections to the Capacitance between Two Electrodes Due to the Presence of Quantum Confined System

    OpenAIRE

    Macucci, M.; K. Hess

    1998-01-01

    We have studied the capacitance between two parallel plates enclosing a quantum confined system and its dependence on the applied voltage. The concepts of capacitance and differential capacitance are discussed together with their applicability to systems characterized by single.electron tunneling. We determine the tunneling thresholds by means of a formalism based on the minimization of the system free energy and we retrieve, as a special case, Luryi's quantum capacitance formula. We apply ou...

  14. An Annular Mechanical Temperature Compensation Structure for Gas-Sealed Capacitive Pressure Sensor

    OpenAIRE

    Kohei Higuchi; Yonggang Jiang; Kazusuke Maenaka; Hidekuni Takao; Xiuchun Hao

    2012-01-01

    A novel gas-sealed capacitive pressure sensor with a temperature compensation structure is reported. The pressure sensor is sealed by Au-Au diffusion bonding under a nitrogen ambient with a pressure of 100 kPa and integrated with a platinum resistor-based temperature sensor for human activity monitoring applications. The capacitance-pressure and capacitance-temperature characteristics of the gas-sealed capacitive pressure sensor without temperature compensation structure are calculated. It is...

  15. Mechanism for defoaming by oils and calcium soap in aqueous systems.

    Science.gov (United States)

    Zhang, Hui; Miller, Clarence A; Garrett, Peter R; Raney, Kirk H

    2003-07-15

    The effect of oils, hardness, and calcium soap on foam stability of aqueous solutions of commercial surfactants was investigated. For conditions where negligible calcium soap was formed, stability of foams made with 0.1 wt% solutions of a seven-EO alcohol ethoxylate containing dispersed drops of n-hexadecane, triolein, or mixtures of these oils with small amounts of oleic acid could be understood in terms of entry, spreading, and bridging coefficients, i.e., ESB analysis. However, foams made from solutions containing 0.01 wt% of three-EO alcohol ethoxysulfate sodium salt and the same dispersed oils were frequently more stable than expected based on ESB analysis, reflecting that repulsion due to overlap of electrical double layers in the asymmetric oil-water-air film made oil entry into the air-water interface more difficult than the theory predicts. When calcium soap was formed in situ by the reaction of fatty acids in the oil with calcium, solid soap particles were observed at the surfaces of the oil drops. The combination of oil and calcium soap produced a synergistic effect facilitating the well-known bridging instability of foam films or Plateau borders and producing a substantial defoaming effect. A possible mechanism of instability involving increases in disjoining pressure at locations where small soap particles approach the air-water interface is discussed. For both surfactants with the triolein-oleic acid mixtures, calculated entry and bridging coefficients for conditions when calcium soap formed were positive shortly after foam generation but negative at equilibrium. These results are consistent with the experimental observation that most defoaming action occurred shortly after foam generation rather than at later times.

  16. Optimal R&D investment strategies with quantity competition under the threat of superior entry

    OpenAIRE

    Lukach, R.; Kort, P.M.; Plasmans, J.E.J.

    2005-01-01

    This paper studies R&D investment decisions of a firm facing the threat of new technology entry and subject to technical uncertainty. We distinguish four scenarios: inevitable entry, entry deterrence, entry blockade, and non-credible entry threat. The entry threat stimulates the incumbent to innovate in case entry prevention is possible, but discourages R&D if entry is inevitable. In the case of entry deterrence the incumbent successfully prevents entry by innovating. Greater technical uncert...

  17. Comparison of C-V measurement methods for RF-MEMS capacitive switches

    NARCIS (Netherlands)

    Wang, J; Salm, Cora; Schmitz, Jurriaan

    2013-01-01

    The applicability of several capacitance-voltage measurement methods is investigated for the on-wafer characterization of RF-MEMS capacitive switches. These devices combine few-picofarad capacitance with a high quality factor. The standard quasistatic and high-frequency measurements are employed, as

  18. Simplified Capacitance Monitoring for the Determination of Campylobacter spp. Growth Rates

    Science.gov (United States)

    Capacitance monitoring is commonly used as an efficient means to measure growth curves of bacterial pathogens. However, the use of capacitance monitoring with Campylobacter spp. was previously determined difficult due to the complexity of the required media. We investigated capacitance monitoring ...

  19. Artificial Neural Network Algorithm for Condition Monitoring of DC-link Capacitors Based on Capacitance Estimation

    DEFF Research Database (Denmark)

    Soliman, Hammam Abdelaal Hammam; Wang, Huai; Gadalla, Brwene Salah Abdelkarim;

    2015-01-01

    challenges. A capacitance estimation method based on Artificial Neural Network (ANN) algorithm is therefore proposed in this paper. The implemented ANN estimated the capacitance of the DC-link capacitor in a back-toback converter. Analysis of the error of the capacitance estimation is also given...

  20. Indirect activation of neuronal noncapacitative Ca2+ entry is the final step involved in the neurotoxic effect of Tityus serrulatus scorpion beta-toxin.

    Science.gov (United States)

    Grolleau, Françoise; Stankiewicz, Maria; Kielbasiewicz, Ewa; Martin-Eauclaire, Marie-France; Lavialle, Céline; De Vente, Jan; Lapied, Bruno

    2006-03-01

    Interweaving strategies of electrophysiology, calcium imaging and immunocytochemistry bring new insights into the mode of action of the Brazilian scorpion Tityus serrulatusbeta-toxin VII. Pacemaker dorsal unpaired median neurons isolated from the cockroach central nervous system were used to study the effects of toxin VII. In current-clamp, 50 nm toxin VII produced a membrane depolarization and reduced spiking. At 200 nM, depolarization associated with multiphasic effects was seen. After artificial hyperpolarization, plateau potentials on which spontaneous electrical activity appeared were observed. In voltage clamp, toxin VII induced a negative shift of the voltage dependence of sodium current activation without significant effect on steady-state inactivation. In addition, toxin VII produced a permanent TTX-sensitive holding inward current, indicating that background sodium channels were targeted by beta-toxin. Cell-attached patch recordings indicated that these channels were switched from unclustered single openings to current fluctuating between distinct subconductance levels exhibiting increased open probability and open-time distribution. Toxin VII also produced a TTX-sensitive [Ca2+]i rise. Immunostaining with Cav2.2(alpha1b) antibodies and calcium imaging data obtained with omega-CgTx GVIA indicated that N-type high-voltage-activated calcium channels initiated calcium influx and were an essential intermediate in the pathway linking toxin VII-modified sodium channels to the activation of an additional route for calcium entry. By using inhibitors of (i) noncapacitative calcium entry (inhibitor LOE-908), (ii) NO-sensitive guanylyl cyclase (ODQ) and (iii) phosphodiesterase 2 (EHNA), together with cGMP antibodies, we demonstrated that noncapacitative calcium entry was the final step in a complex combination of events that was initiated by toxin VII-alteration of sodium channels and then involved successive activation of other membrane ion channels. PMID:16553610

  1. Modes and orders of market entry

    DEFF Research Database (Denmark)

    Ulhøi, John Parm

    2012-01-01

    This paper focuses on the initial questions of how and when to enter a market from the perspective of a firm. By entry mode is meant a firm’s strategy (innovation or imitation) for entering the market in response to environmental changes. Entry order refers to the related issue of market timing...... (first-mover or follower). Invention is understood as the conversion of human creativity, time and financial resources into new ideas. Innovation in turn reflects the practical and financial return on such investments. While there is little disagreement about what an innovator strategy is, imitative...... strategies are more ambiguous. Based on a corporate technology and innovation strategy perspective, the paper reconceptualises and extends existing modes and orders of market entry, and in particular clarifies the ambiguity associated with imitative strategies. Four distinct imitator strategies...

  2. Simultaneous Characterization of Instantaneous Young’s Modulus and Specific Membrane Capacitance of Single Cells Using a Microfluidic System

    Directory of Open Access Journals (Sweden)

    Yang Zhao

    2015-01-01

    Full Text Available This paper presents a microfluidics-based approach capable of continuously characterizing instantaneous Young’s modulus (Einstantaneous and specific membrane capacitance (Cspecific membrane of suspended single cells. In this method, cells were aspirated through a constriction channel while the cellular entry process into the constriction channel was recorded using a high speed camera and the impedance profiles at two frequencies (1 kHz and 100 kHz were simultaneously measured by a lock-in amplifier. Numerical simulations were conducted to model cellular entry process into the constriction channel, focusing on two key parameters: instantaneous aspiration length (Linstantaneous and transitional aspiration length (Ltransitional, which was further translated to Einstantaneous. An equivalent distribution circuit model for a cell travelling in the constriction channel was used to determine Cspecific membrane. A non-small-cell lung cancer cell line 95C (n = 354 was used to evaluate this technique, producing Einstantaneous of 2.96 ± 0.40 kPa and Cspecific membrane of 1.59 ± 0.28 μF/cm2. As a platform for continuous and simultaneous characterization of cellular Einstantaneous and Cspecific membrane, this approach can facilitate a more comprehensive understanding of cellular biophysical properties.

  3. Entry Mode and Performance of Nordic Firms

    DEFF Research Database (Denmark)

    Wulff, Jesper

    2015-01-01

    This study investigates whether the relationship between mode of international market entry and non-location bound international experience is weaker for firms that are large or have a high foreign to total sales ratio, labeled multinational experience. Empirical evidence based on 250 foreign mar...... including the proposed moderating effect, on average, yield higher post-entry performance. This study sheds light on inconsistent results found in previous research investigating the impact of international experience and has practical implications for managerial decision-making....

  4. Strontium and calcium determination in sea fishes in neighborhood of Angra nuclear power plant

    International Nuclear Information System (INIS)

    Strontium-90 is an important radionuclide present in the liquid effluents of the Angra Nuclear Power Plant, located in the coastline of Rio de Janeiro State. It has a long effective half-life, easy entry into food chain due to its chemical similarity to calcium and stays for a long time in solution. With the aim of calculating the concentration factor (CF) for 90 Sr and observed ratio (OR) in the most abundant local fish, it was determined the strontium and calcium content in the edible fraction of nine species and in sea water by atomic absorption spectrophotometry. (author)

  5. Comprehensive characterization of interface and oxide states in metal/oxide/semiconductor capacitors by pulsed mode capacitance and differential isothermal capacitance spectroscopy

    OpenAIRE

    Muret, Pierre

    2014-01-01

    In metal/insulator/semi-conductor structures, capacitance-voltage characteristics and capacitance or voltage transients can be measured in different conditions, which are described and implemented. Each method contains information about charges which are accommodated, captured or emitted by energy levels or bands at interface and inside the oxide. Pulsed capacitance measurements and differential isothermal procedures are analysed and performed. Calibration of the energy scale from the interfa...

  6. Cytosolic organelles shape calcium signals and exo-endocytotic responses of chromaffin cells.

    Science.gov (United States)

    García, Antonio G; Padín, Fernando; Fernández-Morales, José C; Maroto, Marcos; García-Sancho, Javier

    2012-01-01

    The concept of stimulus-secretion coupling was born from experiments performed in chromaffin cells 50 years ago. Stimulation of these cells with acetylcholine enhances calcium (Ca(2+)) entry and this generates a transient elevation of the cytosolic Ca(2+) concentration ([Ca(2+)](c)) that triggers the exocytotic release of catecholamines. The control of the [Ca(2+)](c) signal is complex and depends on various classes of plasmalemmal calcium channels, cytosolic calcium buffers, the uptake and release of Ca(2+) from cytoplasmic organelles, such as the endoplasmic reticulum, mitochondria, chromaffin vesicles and the nucleus, and Ca(2+) extrusion mechanisms, such as the plasma membrane Ca(2+)-stimulated ATPase, and the Na(+)/Ca(2+) exchanger. Computation of the rates of Ca(2+) fluxes between the different cell compartments support the proposal that the chromaffin cell has developed functional calcium tetrads formed by calcium channels, cytosolic calcium buffers, the endoplasmic reticulum, and mitochondria nearby the exocytotic plasmalemmal sites. These tetrads shape the Ca(2+) transients occurring during cell activation to regulate early and late steps of exocytosis, and the ensuing endocytotic responses. The different patterns of catecholamine secretion in response to stress may thus depend on such local [Ca(2+)](c) transients occurring at different cell compartments, and generated by redistribution and release of Ca(2+) by cytoplasmic organelles. In this manner, the calcium tetrads serve to couple the variable energy demands due to exo-endocytotic activities with energy production and protein synthesis. PMID:22209033

  7. Inhibitory action of oestrogen on calcium-induced mitosis in rat bone marrow and thymus.

    Science.gov (United States)

    Smith, G R; Gurson, M L; Riddell, A J; Perris, A D

    1975-04-01

    In the male rat injections of CaCl-2 and MgCl-2 stimulated mitosis in bone marrow and thymus tissue. The magnesium salt was also mitogenic in the normal female, but calcium only exerted its mitogenic effect after ovariectomy. Oestradiol, but not progesterone replacement therpy abolished calcium-induced mitosis in the ovariectomized rat. The inability of calcium to stimulate cell division was also apparent in the thyroparathyroidectomized female rat, suggesting the oestradiol blockage did not operate via some indirect action on the calcium homeostatic hormones calcitonin or parathyroid hormone. When thymic lymphocytes derived from male or female rats were isolated and maintained in suspension, increased calcium or magnesium concentrations in the culture medium stimulated the entry of cells into mitosis. Addition of oestradiol to the culture medium abolished the mitogenic effect of increased calcium levels, but had no effect on magnesium-induced proliferation. These experiments suggested that oestradiol might act at the cell surface to prevent the influx of calcium but not magnesium ions into the interior of the cell and thus to block the sequence of biochemical events which led to the initiation of DNA synthesis and culminate in mitosis.

  8. An Analytical Model for Fringing Capacitance in Double gate Hetero Tunnel FET and Analysis of effect of Traps and Oxide charges on Fringing Capacitance

    Directory of Open Access Journals (Sweden)

    Brinda Bhowmick

    2012-02-01

    Full Text Available In this paper fringe capacitance of double hetero gate Tunnel FET has been studied. The physical model for fringe capacitance is derived considering source gate overlap and gate drain non overlap. Inerface trap charge and oxide charges are also introduced under positive bias stress and hot carrier stress and their effect on fringe capacitance is also studied. The fringe capacitance is significant speed limiter in Double gate technology. The model is tested by comparing with simulation results obtained from Sentauras TCAD simulations.

  9. SLO BK Potassium Channels Couple Gap Junctions to Inhibition of Calcium Signaling in Olfactory Neuron Diversification.

    Science.gov (United States)

    Alqadah, Amel; Hsieh, Yi-Wen; Schumacher, Jennifer A; Wang, Xiaohong; Merrill, Sean A; Millington, Grethel; Bayne, Brittany; Jorgensen, Erik M; Chuang, Chiou-Fen

    2016-01-01

    The C. elegans AWC olfactory neuron pair communicates to specify asymmetric subtypes AWCOFF and AWCON in a stochastic manner. Intercellular communication between AWC and other neurons in a transient NSY-5 gap junction network antagonizes voltage-activated calcium channels, UNC-2 (CaV2) and EGL-19 (CaV1), in the AWCON cell, but how calcium signaling is downregulated by NSY-5 is only partly understood. Here, we show that voltage- and calcium-activated SLO BK potassium channels mediate gap junction signaling to inhibit calcium pathways for asymmetric AWC differentiation. Activation of vertebrate SLO-1 channels causes transient membrane hyperpolarization, which makes it an important negative feedback system for calcium entry through voltage-activated calcium channels. Consistent with the physiological roles of SLO-1, our genetic results suggest that slo-1 BK channels act downstream of NSY-5 gap junctions to inhibit calcium channel-mediated signaling in the specification of AWCON. We also show for the first time that slo-2 BK channels are important for AWC asymmetry and act redundantly with slo-1 to inhibit calcium signaling. In addition, nsy-5-dependent asymmetric expression of slo-1 and slo-2 in the AWCON neuron is necessary and sufficient for AWC asymmetry. SLO-1 and SLO-2 localize close to UNC-2 and EGL-19 in AWC, suggesting a role of possible functional coupling between SLO BK channels and voltage-activated calcium channels in AWC asymmetry. Furthermore, slo-1 and slo-2 regulate the localization of synaptic markers, UNC-2 and RAB-3, in AWC neurons to control AWC asymmetry. We also identify the requirement of bkip-1, which encodes a previously identified auxiliary subunit of SLO-1, for slo-1 and slo-2 function in AWC asymmetry. Together, these results provide an unprecedented molecular link between gap junctions and calcium pathways for terminal differentiation of olfactory neurons.

  10. Study of materials for the design of MEMS capacitive pressure sensor

    Science.gov (United States)

    Jindal, Sumit Kumar; Raghuwanshi, Sanjeev Kumar

    2016-04-01

    Highly sensitive MEMS capacitive pressure sensor is nowadays used for many different applications such as aerospace, automobile, Bio-MEMS etc. This paper deals with study and comparison of different types of materials that can be used in design of MEMS capacitive pressure sensor. Initially principle and design of basic MEMS capacitive pressure sensor is explained. In the next section the properties of different materials is elaborated. The centre deflection of the diaphragm is calculated using COMSOL Multiphysics and Capacitance is calculated using MATLAB simulation. From the capacitance calculated sensitivity of the materials can be interpreted. The analysis is carried out for a pressure range of 0 to 0.1 MPa.

  11. MEMS Capacitive Pressure Sensors: A Review on Recent Development and Prospective

    Directory of Open Access Journals (Sweden)

    Eswaran P

    2013-06-01

    Full Text Available Recently MEMS Capacitive Pressure Sensor gains more advantage over micromachined piezoresistive pressure sensor due to high sensitivity, low power consumption, free from temperature effects, IC compatibility, etc,. The spectrum of capacitive pressure sensor application is increasing, hence it is essential to review the path of technological development and further prospective of micromachinedcapacitive pressure sensor. This paper focuses on the review of various types of capacitive pressure sensor principle, MEMS materials used in fabrication, procedures adopted in microfabrication for silicon and polymer material diaphragm, bonding and packaging techniques used. Selected result on capacitive sensitivity, effect of temperature on capacitive sensitivity was also presented. Finally, the development of smart sensor was discussed.

  12. Calcium – how and why?

    Indian Academy of Sciences (India)

    J K Jaiswal

    2001-09-01

    Calcium is among the most commonly used ions, in a multitude of biological functions, so much so that it is impossible to imagine life without calcium. In this article I have attempted to address the question as to how calcium has achieved this status with a brief mention of the history of calcium research in biology. It appears that during the origin and early evolution of life the Ca2+ ion was given a unique opportunity to be used in several biological processes because of its unusual physical and chemical properties.

  13. Calcium Phosphate Biomaterials: An Update

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Current calcium phosphate (CaP) biomaterials for bone repair, substitution, augmentation and regeneration include hydroxyapatite ( HA ) from synthetic or biologic origin, beta-tricalcium phosphate ( β-TCP ) , biphasic calcium phosphate (BCP), and are available as granules, porous blocks, components of composites (CaP/polymer) cements, and as coatings on orthopedic and dental implants. Experimental calcium phosphate biomaterials include CO3- and F-substituted apatites, Mg-and Zn-substituted β-TCP, calcium phosphate glasses. This paper is a brief review of the different types of CaP biomaterials and their properties such as bioactivity, osteoconductivity, osteoinductivity.

  14. Cardiovascular Effects of Calcium Supplements

    Directory of Open Access Journals (Sweden)

    Ian R. Reid

    2013-07-01

    Full Text Available Calcium supplements reduce bone turnover and slow the rate of bone loss. However, few studies have demonstrated reduced fracture incidence with calcium supplements, and meta-analyses show only a 10% decrease in fractures, which is of borderline statistical and clinical significance. Trials in normal older women and in patients with renal impairment suggest that calcium supplements increase the risk of cardiovascular disease. To further assess their safety, we recently conducted a meta-analysis of trials of calcium supplements, and found a 27%–31% increase in risk of myocardial infarction, and a 12%–20% increase in risk of stroke. These findings are robust because they are based on pre-specified analyses of randomized, placebo-controlled trials and are consistent across the trials. Co-administration of vitamin D with calcium does not lessen these adverse effects. The increased cardiovascular risk with calcium supplements is consistent with epidemiological data relating higher circulating calcium concentrations to cardiovascular disease in normal populations. There are several possible pathophysiological mechanisms for these effects, including effects on vascular calcification, vascular cells, blood coagulation and calcium-sensing receptors. Thus, the non-skeletal risks of calcium supplements appear to outweigh any skeletal benefits, and are they appear to be unnecessary for the efficacy of other osteoporosis treatments.

  15. Calcium measurement methods

    Directory of Open Access Journals (Sweden)

    CarloAlberto Redi

    2010-09-01

    Full Text Available Rightly stressed by prof. Wolfgang Walz in the Preface to the series Neuromethods series, the “careful application of methods is probably the most important step in the process of scientific inquiry”. Thus, I strongly suggest to all those interested in calcium signaling and especially to the new-comers in the hot topic of neuroscience (which has so much space even in science-society debate for its implications in legal issues and in the judge-decision process to take profit from this so well edited book. I am saying this since prof. Verkhratsky and prof. Petersen......

  16. 21 CFR 573.240 - Calcium periodate.

    Science.gov (United States)

    2010-04-01

    ... with calcium hydroxide or calcium oxide to form a substance consisting of not less than 60 percent by... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium periodate. 573.240 Section 573.240 Food... Additive Listing § 573.240 Calcium periodate. The food additive calcium periodate may be safely used...

  17. 21 CFR 573.260 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 573.260 Section 573.260 Food and... Listing § 573.260 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used as an anticaking agent in animal feed, provided that the amount of calcium silicate does...

  18. Calcium entry induces mitochondrial oxidant stress in vagal neurons at risk in Parkinson’s disease

    OpenAIRE

    Goldberg, Joshua A.; Guzman, Jaime N.; Estep, Chad M.; Ilijic, Ema; Kondapalli, Jyothisri; Sanchez-Padilla, Javier; Surmeier, D. James

    2012-01-01

    Mitochondrial oxidant stress is widely viewed as critical to pathogenesis in Parkinson’s disease. But the origins of this stress are poorly defined. One possibility is that it arises from the metabolic demands associated with regenerative activity. To test this hypothesis, neurons in the dorsal motor nucleus of the vagus (DMV), a population cholinergic neurons that shows signs of pathology in the early stages of Parkinson’s disease, were characterized in mouse brain slices. DMV neurons were s...

  19. 19 CFR 10.31 - Entry; bond.

    Science.gov (United States)

    2010-04-01

    ... exported to Canada or Mexico (see § 181.53 of this chapter). ... voucher of the carnet shall serve as the entry. (3) In addition to the data usually shown on a regular... intended for display or demonstration, if brought into the United States by a resident of Canada,...

  20. Perceptions regarding strategic and structural entry barriers

    NARCIS (Netherlands)

    Lutz, Clemens H. M.; Kemp, Ron G. M.; Dijkstra, S. Gerhard

    2010-01-01

    This article uses factor analysis to identify the underlying dimensions of strategic and structural entry barriers. We find that, in the perception of firms, both types of barriers are important and that the effectiveness of strategic barriers depends on attributes of the market structure. Based on