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Sample records for capacitative calcium entry

  1. 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.

  2. Characterization of T cell mutants with defects in capacitative calcium entry: genetic evidence for the physiological roles of CRAC channels.

    Science.gov (United States)

    Fanger, C M; Hoth, M; Crabtree, G R; Lewis, R S

    1995-11-01

    Prolonged Ca2+ influx is an essential signal for the activation of T lymphocytes by antigen. This influx is thought to occur through highly selective Ca2+ release-activated Ca2+ (CRAC) channels that are activated by the depletion of intracellular Ca2+ stores. We have isolated mutants of the Jurkat human T cell line NZdipA to explore the molecular mechanisms that underlie capacitative Ca2+ entry and to allow a genetic test of the functions of CRAC channels in T cells. Five mutant cell lines (CJ-1 through CJ-5) were selected based on their failure to express a lethal diphtheria toxin A chain gene and a lacZ reporter gene driven by NF-AT, a Ca(2+)- and protein kinase C-dependent transcription factor. The rate of Ca2+ influx evoked by thapsigargin was reduced to varying degrees in the mutant cells whereas the dependence of NF-AT/lacZ gene transcription on [Ca2+]i was unaltered, suggesting that the transcriptional defect in these cells is caused by a reduced level of capacitative Ca2+ entry. We examined several factors that determine the rate of Ca2+ entry, including CRAC channel activity, K(+)-channel activity, and Ca2+ clearance mechanisms. The only parameter found to be dramatically altered in most of the mutant lines was the amplitude of the Ca2+ current (ICRAC), which ranged from 1 to 41% of that seen in parental control cells. In each case, the severity of the ICRAC defect was closely correlated with deficits in Ca2+ influx rate and Ca(2-)-dependent gene transcription. Behavior of the mutant cells provides genetic evidence for several roles of ICRAC in T cells. First, mitogenic doses of ionomycin appear to elevate [Ca2+]i primarily by activating CRAC channels. Second, ICRAC promotes the refilling of empty Ca2+ stores. Finally, CRAC channels are solely responsible for the Ca2+ influx that underlies antigen-mediated T cell activation. These mutant cell lines may provide a useful system for isolating, expressing, and exploring the functions of genes involved in

  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. Negative Feedback for Small Capacitive Touchscreen Interfaces: A Usability Study for Data Entry Tasks.

    Science.gov (United States)

    Parikh, S P; Esposito, J M

    2012-01-01

    Touchscreen technology has become pervasive in the consumer product arena over the last decade, offering some distinct advantages such as software reconfigurable interfaces and the removal of space consuming mice and keyboards. However, there are significant drawbacks to these devices that have limited their adoption by some users. Most notably, standard touchscreens demand the user's visual attention and require them to look at the input device to avoid pressing the wrong button. This issue is particularly important for mobile, capacitive sensing, nonstylus devices, such as the iPhone where small button sizes can generate high error rates. While previous work has shown the benefits of augmenting such interfaces with audio or vibrotactile feedback, only positive feedback (confirmation of button presses) has been considered. In this paper, we present a simple prototype interface that provides negative vibrotactile feedback. By negative, we mean feedback is generated when an inactive or ambiguous part of the screen, such as the area between two buttons, is touched. First, we present a usability study comparing positive and negative vibrotactile feedback for a benchmark numerical data entry task. The difference in performance is not statistically significant, implying negative feedback provides comparable benefits. Next, based on the experimenter's observations and the users comments, we introduce a multimodal feedback strategy-combining complementary positive audio and negative vibrotactile signals. User tests on a text entry experiment show that, with multimodal feedback, users exhibit a (statistically significant) 24 percent reduction in corrective key presses, as compared to positive audio feedback alone. Exit survey comments indicate that users favor multimodal feedback.

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

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    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.

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

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    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

  7. Suppression of EGF-induced cell proliferation by the blockade of Ca2+ mobilization and capacitative Ca2+ entry in mouse mammary epithelial cells.

    Science.gov (United States)

    Ichikawa, J; Kiyohara, T

    2001-09-01

    The role of intracellular Ca2+ stores and capacitative Ca2+ entry on EGF-induced cell proliferation was investigated in mouse mammary epithelial cells. We have previously demonstrated that EGF enhances Ca2+ mobilization (release of Ca2+ from intracellular Ca2+ stores) and capacitative Ca2+ entry correlated with cell proliferation in mouse mammary epithelial cells. To confirm their role on EGF-induced cell cycle progression, we studied the effects of 2,5-di-tert-butylhydroquinone (DBHQ), a reversible inhibitor of the Ca2+ pump of intracellular Ca2+ stores, and SK&F 96365, a blocker of capacitative Ca2+ entry, on mitotic activity induced by EGF. Mitotic activity was examined using an antibody to PCNA for immunocytochemistry. SK&F 96365 inhibited capacitative Ca2+ entry in a dose-dependent manner (I50: 1-5 microM). SK&F 96365 also inhibited EGF-induced cell proliferation in the same range of concentration (I50: 1-5 microM). DBHQ suppressed [Ca2+]i response to UTP and thus depleted completely Ca2+ stores at 5 microM. DBHQ also inhibited EGF-induced cell proliferation at an I50 value of approximately 10 microM. The removal of these inhibitors from the culture medium increased the reduced mitotic activity reversibly. Using a fluorescent assay of DNA binding of ethidium bromide, no dead cells were detected in any of the cultures. These results indicate that the inhibitory effects of SK&F 96365 and DBHQ on cell proliferation were due to the inhibition of capacitative Ca2+ entry and Ca2+ mobilization suggesting the importance of capacitative Ca2+ entry and Ca2+ mobilization in the control of EGF-induced cell cycle progression in mouse mammary epithelial cells.

  8. Adaptation of mammalian auditory hair cell mechanotransduction is independent of calcium entry.

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    Peng, Anthony W; Effertz, Thomas; Ricci, Anthony J

    2013-11-20

    Adaptation is a hallmark of hair cell mechanotransduction, extending the sensory hair bundle dynamic range while providing mechanical filtering of incoming sound. In hair cells responsive to low frequencies, two distinct adaptation mechanisms exist, a fast component of debatable origin and a slow myosin-based component. It is generally believed that Ca(2+) entry through mechano-electric transducer channels is required for both forms of adaptation. This study investigates the calcium dependence of adaptation in the mammalian auditory system. Recordings from rat cochlear hair cells demonstrate that altering Ca(2+) entry or internal Ca(2+) buffering has little effect on either adaptation kinetics or steady-state adaptation responses. Two additional findings include a voltage-dependent process and an extracellular Ca(2+) binding site, both modulating the resting open probability independent of adaptation. These data suggest that slow motor adaptation is negligible in mammalian auditory cells and that the remaining adaptation process is independent of calcium entry.

  9. T Cell Receptor Mediated Calcium Entry Requires Alternatively Spliced Cav1.1 Channels.

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    Didi Matza

    Full Text Available The process of calcium entry in T cells is a multichannel and multi-step process. We have studied the requirement for L-type calcium channels (Cav1.1 α1S subunits during calcium entry after TCR stimulation. High expression levels of Cav1.1 channels were detected in activated T cells. Sequencing and cloning of Cav1.1 channel cDNA from T cells revealed that a single splice variant is expressed. This variant lacks exon 29, which encodes the linker region adjacent to the voltage sensor, but contains five new N-terminal exons that substitute for exons 1 and 2, which are found in the Cav1.1 muscle counterpart. Overexpression studies using cloned T cell Cav1.1 in 293HEK cells (that lack TCR suggest that the gating of these channels was altered. Knockdown of Cav1.1 channels in T cells abrogated calcium entry after TCR stimulation, suggesting that Cav1.1 channels are controlled by TCR signaling.

  10. Adaptation of mammalian auditory hair cell mechanotransduction is independent of calcium entry

    OpenAIRE

    Peng, A.W.; Effertz, T.; Ricci, A.J.

    2013-01-01

    Adaptation is a hallmark of hair cell mechanotransduction, extending the sensory hair bundle dynamic range while providing mechanical filtering of incoming sound. In hair cells responsive to low frequencies, two distinct adaptation mechanisms exist, a fast component of debatable origin and a slow myosin-based component. It is generally believed that Ca2+ entry through mechano-electric transducer channels is required for both forms of adaptation. This study investigates the calcium dependence ...

  11. Intracellular calcium movements of boar spermatozoa during 'in vitro' capacitation and subsequent acrosome exocytosis follow a multiple-storage place, extracellular calcium-dependent model.

    Science.gov (United States)

    Yeste, M; Fernández-Novell, J M; Ramió-Lluch, L; Estrada, E; Rocha, L G; Cebrián-Pérez, J A; Muiño-Blanco, T; Concha, I I; Ramírez, A; Rodríguez-Gil, J E

    2015-07-01

    This work analysed intracellular calcium stores of boar spermatozoa subjected to 'in vitro' capacitation (IVC) and subsequent progesterone-induced acrosome exocytosis (IVAE). Intracellular calcium was analysed through two calcium markers with different physico-chemical properties, Fluo-3 and Rhod-5N. Indicative parameters of IVC and IVAE were also evaluated. Fluo-3 was located at both the midpiece and the whole head. Rhod-5N was present at the sperm head. This distribution did not change in any of the assayed conditions. Induction of IVC was concomitant with an increase in both head and midpiece Ca(2+) signals. Additionally, while IVC induction was concurrent with a significant (p sperm membrane permeability, no significant changes were observed in O2 consumption and ATP levels. Incubation of boar spermatozoa in the absence of calcium showed a loss of both Ca(2+) labellings concomitantly with the sperm's inability to achieve IVC. The absence of extracellular calcium also induced a severe decrease in the percentage of spermatozoa exhibiting high mitochondrial membrane potential (hMMP). The IVAE was accompanied by a fast increase in both Ca(2+) signalling in control spermatozoa. These peaks were either not detected or much lessened in the absence of calcium. Remarkably, Fluo-3 marking at the midpiece increased after progesterone addition to sperm cells incubated in a medium without Ca(2+) . The simultaneous addition of progesterone with the calcium chelant EGTA inhibited IVAE, and this was accompanied by a significant (p boar spermatozoa present different calcium deposits with a dynamic equilibrium among them and with the extracellular environment. Additionally, the modulation role of the intracellular calcium in spermatozoa function seems to rely on its precise localization in boar spermatozoa.

  12. Selective inhibition of Ebola entry with selective estrogen receptor modulators by disrupting the endolysosomal calcium

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    Fan, Hanlu; Du, Xiaohong; Zhang, Jingyuan; Zheng, Han; Lu, Xiaohui; Wu, Qihui; Li, Haifeng; Wang, Han; Shi, Yi; Gao, George; Zhou, Zhuan; Tan, Dun-Xian; Li, Xiangdong

    2017-01-01

    The Ebola crisis occurred in West-Africa highlights the urgency for its clinical treatments. Currently, no Food and Drug Administration (FDA)-approved therapeutics are available. Several FDA-approved drugs, including selective estrogen receptor modulators (SERMs), possess selective anti-Ebola activities. However, the inhibitory mechanisms of these drugs remain elusive. By analyzing the structures of SERMs and their incidental biological activity (cholesterol accumulation), we hypothesized that this incidental biological activity induced by SERMs could be a plausible mechanism as to their inhibitory effects on Ebola infection. Herein, we demonstrated that the same dosages of SERMs which induced cholesterol accumulation also inhibited Ebola infection. SERMs reduced the cellular sphingosine and subsequently caused endolysosomal calcium accumulation, which in turn led to blocking the Ebola entry. Our study clarified the specific anti-Ebola mechanism of SERMs, even the cationic amphiphilic drugs (CADs), this mechanism led to the endolysosomal calcium as a critical target for development of anti-Ebola drugs. PMID:28117364

  13. [Capacitative Ca²⁺ entry is involved in ACh-induced distal colon smooth muscle contraction in rats].

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    Kong, De-Hu; Zhou, Hua; Song, Jie; Ke, Dao-Ping; Hu, Jin-Lan; Li, Zhong-Wen; Ma, Rong

    2006-04-25

    Contraction of smooth muscle cells is triggered by an increase in cytosolic Ca(2+) upon agonist stimulation. Ca(2+) influx across the plasma membrane constitutes a major component of the agonist-induced response in smooth muscle cells. Traditionally, voltage-operated Ca(2+) channel (VOCC) is considered as the channel mediating the Ca(2+) entry. However, this view has been challenged by recent discoveries, which demonstrated that other types of ion channels, such as store-operated and/or receptor-operated Ca(2+) channels (SOCC and/or ROCC), also participate in Ca(2+) response induced by agonists in smooth muscle cells. SOCC is defined as the channel activated in response to the depletion of the internal Ca(2+) stores, an event secondary to G protein coupled receptor or receptor tyrosine kinase stimulation. The Ca(2+) flow mediated by SOCC is termed as capacitative Ca(2+) entry (CCE). Previous study from other group has demonstrated that VOCC played a predominant role in ACh-induced contraction of distal colon smooth muscle in guinea pig. However, whether SOCC participates in the agonist-induced contractile response in this particular tissue is unknown. The present study was performed to investigate the role of CCE in ACh-induced mechanical activity of distal colon smooth muscle in rats. The contractile function of the smooth muscle was assessed by measuring isometric force of isolated rat distal colon rings. We showed that both high extracellular K(+) (40 mmol/L) and ACh (5 mumol/L) evoked striking contraction of the smooth muscle. The contractile responses were almost abolished by removal of extracellular Ca(2+) with ethylene glycol-bis(2-aminoethylether)-N,N,N',N' tetraacetic acid (EGTA), suggesting a critical contribution of extracellular source of Ca(2+) to the contraction. Verapamil (5 mumol/L), an L-type VOCC blocker, significantly attenuated, but didn't completely eliminate the high K(+)- and ACh-induced contraction (74% and 41% for high K(+) and ACh

  14. Atlastin regulates store-operated calcium entry for nerve growth factor-induced neurite outgrowth

    Science.gov (United States)

    Li, Jing; Yan, Bing; Si, Hongjiang; Peng, Xu; Zhang, Shenyuan L.; Hu, Junjie

    2017-01-01

    Homotypic membrane fusion of the endoplasmic reticulum (ER) is mediated by a class of dynamin-like GTPases known as atlastin (ATL). Depletion of or mutations in ATL cause an unbranched ER morphology and hereditary spastic paraplegia (HSP), a neurodegenerative disease characterized by axon shortening in corticospinal motor neurons and progressive spasticity of the lower limbs. How ER shaping is linked to neuronal defects is poorly understood. Here, we show that dominant-negative mutants of ATL1 in PC-12 cells inhibit nerve growth factor (NGF)-induced neurite outgrowth. Overexpression of wild-type or mutant ATL1 or depletion of ATLs alters ER morphology and affects store-operated calcium entry (SOCE) by decreasing STIM1 puncta formation near the plasma membrane upon calcium depletion of the ER. In addition, blockage of the STIM1-Orai pathway effectively abolishes neurite outgrowth of PC-12 cells stimulated by NGF. These results suggest that SOCE plays an important role in neuronal regeneration, and mutations in ATL1 may cause HSP, partly by undermining SOCE. PMID:28240257

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

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    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.

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    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.

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    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. Sustained calcium entry through P2X nucleotide receptor channels in human airway epithelial cells.

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    Zsembery, Akos; Boyce, Amanda T; Liang, Lihua; Peti-Peterdi, János; Bell, P Darwin; Schwiebert, Erik M

    2003-04-11

    Purinergic receptor stimulation has potential therapeutic effects for cystic fibrosis (CF). Thus, we explored roles for P2Y and P2X receptors in stably increasing [Ca(2+)](i) in human CF (IB3-1) and non-CF (16HBE14o(-)) airway epithelial cells. Cytosolic Ca(2+) was measured by fluorospectrometry using the fluorescent dye Fura-2/AM. Expression of P2X receptor (P2XR) subtypes was assessed by immunoblotting and biotinylation. In IB3-1 cells, ATP and other P2Y agonists caused only a transient increase in [Ca(2+)](i) derived from intracellular stores in a Na(+)-rich environment. In contrast, ATP induced an increase in [Ca(2+)](i) that had transient and sustained components in a Na(+)-free medium; the sustained plateau was potentiated by zinc or increasing extracellular pH. Benzoyl-benzoyl-ATP, a P2XR-selective agonist, increased [Ca(2+)](i) only in Na(+)-free medium, suggesting competition between Na(+) and Ca(2+) through P2XRs. Biochemical evidence showed that the P2X(4) receptor is the major subtype shared by these airway epithelial cells. A role for store-operated Ca(2+) channels, voltage-dependent Ca(2+) channels, or Na(+)/Ca(2+) exchanger in the ATP-induced sustained Ca(2+) signal was ruled out. In conclusion, these data show that epithelial P2X(4) receptors serve as ATP-gated calcium entry channels that induce a sustained increase in [Ca(2+)](i). In airway epithelia, a P2XR-mediated Ca(2+) signal may have therapeutic benefit for CF.

  19. The BSA-induced Ca(2+ influx during sperm capacitation is CATSPER channel-dependent

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    Ren Dejian

    2009-10-01

    Full Text Available Abstract Background Serum albumin is a key component in mammalian sperm capacitation, a functional maturation process by which sperm become competent to fertilize oocytes. Capacitation is accompanied by several cellular and molecular changes including an increased tyrosine phosphorylation of sperm proteins and a development of hyperactivated sperm motility. Both of these processes require extracellular calcium, but how calcium enters sperm during capacitation is not well understood. Methods BSA-induced changes in intracellular calcium concentration were studied using Fluo-4 and Fura-2 calcium imaging with wild-type and Catsper1 knockout mouse sperm. Results We found that the fast phase of the BSA-induced rises in intracellular calcium concentration was absent in the Catsper1 knockout sperm and could be restored by an EGFP-CATSPER1 fusion protein. The calcium concentration increases were independent of G-proteins and phospholipase C but could be partially inhibited when intracellular pH was clamped. The changes started in the principal piece and propagated toward the sperm head. Conclusion We conclude that the initial phase of the increases in intracellular calcium concentration induced by BSA requires the CATSPER channel, but not the voltage-gated calcium channel. Our findings identify the molecular conduit responsible for the calcium entry required for the sperm motility changes that occur during capacitation.

  20. Dynamic interaction of hTRPC6 with the Orai1-STIM1 complex or hTRPC3 mediates its role in capacitative or non-capacitative Ca(2+) entry pathways.

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    Jardin, Isaac; Gómez, Luis J; Salido, Gines M; Rosado, Juan A

    2009-05-13

    TRPC (canonical transient receptor potential) channel subunits have been shown to assemble into homo- or hetero-meric channel complexes, including different Ca2+-handling proteins, required for the activation of CCE (capacitative Ca2+ entry) or NCCE (non-CCE) pathways. In the present study we found evidence for the dynamic interaction between endogenously expressed hTRPC6 (human TRPC6) with either both Orai1 and STIM1 (stromal interaction molecule 1) or hTRPC3 to participate in CCE or NCCE. Electrotransjection of cells with an anti-hTRPC6 antibody, directed towards the C-terminal region, reduces CCE induced by TPEN [N,N,N',N'-tetrakis-(2-pyridylmethyl)-ethylenediamine], which reduces the intraluminal free Ca2+ concentration. Cell stimulation with thrombin or extensive Ca2+-store depletion by TG (thapsigargin)+ionomycin enhanced the interaction between hTRPC6 and the CCE proteins Orai1 and STIM1. In contrast, stimulation with the diacylglycerol analogue OAG (1-oleoyl-2-acetyl-sn-glycerol) displaces hTRPC6 from Orai1 and STIM1 and enhances the association between hTRPC6 and hTRPC3. The interaction between hTRPC6 and hTRPC3 was abolished by dimethyl-BAPTA [1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid] loading, which indicates that this phenomenon is Ca2+-dependent. These findings support the hypothesis that hTRPC6 participates both in CCE and NCCE through its interaction with the Orai1-STIM1 complex or hTRPC3 respectively.

  1. Elevation of extracellular Ca2+ induces store-operated calcium entry via calcium-sensing receptors: a pathway contributes to the proliferation of osteoblasts.

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    Fen Hu

    Full Text Available AIMS: The local concentration of extracellular Ca(2+ ([Ca(2+]o in bone microenvironment is accumulated during bone remodeling. In the present study we investigated whether elevating [Ca(2+]o induced store-operated calcium entry (SOCE in primary rat calvarial osteoblasts and further examined the contribution of elevating [Ca(2+]o to osteoblastic proliferation. METHODS: Cytosolic Ca(2+ concentration ([Ca(2+]c of primary cultured rat osteoblasts was detected by fluorescence imaging using calcium-sensitive probe fura-2/AM. Osteoblastic proliferation was estimated by cell counting, MTS assay and ATP assay. Agonists and antagonists of calcium-sensing receptors (CaSR as well as inhibitors of phospholipase C (PLC, SOCE and voltage-gated calcium (Cav channels were applied to study the mechanism in detail. RESULTS: Our data showed that elevating [Ca(2+]o evoked a sustained increase of [Ca(2+]c in a dose-dependent manner. This [Ca(2+]c increase was blocked by TMB-8 (Ca(2+ release inhibitor, 2-APB and BTP-2 (both SOCE blockers, respectively, whereas not affected by Cav channels blockers nifedipine and verapamil. Furthermore, NPS2143 (a CaSR antagonist or U73122 (a PLC inhibitor strongly reduced the [Ca(2+]o-induced [Ca(2+]c increase. The similar responses were observed when cells were stimulated with CaSR agonist spermine. These data indicated that elevating [Ca(2+]o resulted in SOCE depending on the activation of CaSR and PLC in osteoblasts. In addition, high [Ca(2+]o significantly promoted osteoblastic proliferation, which was notably reversed by BAPTA-AM (an intracellular calcium chelator, 2-APB, BTP-2, TMB-8, NPS2143 and U73122, respectively, but not affected by Cav channels antagonists. CONCLUSIONS: Elevating [Ca(2+]o induced SOCE by triggering the activation of CaSR and PLC. This process was involved in osteoblastic proliferation induced by high level of extracellular Ca(2+ concentration.

  2. Microtubule remodeling mediates the inhibition of store-operated calcium entry (SOCE) during mitosis in COS-7 cells.

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    Russa, Afadhali Denis; Ishikita, Naoyuki; Masu, Kazuki; Akutsu, Hitomi; Saino, Tomoyuki; Satoh, Yoh-ichi

    2008-12-01

    Regulation of the intracellular calcium ion concentration ([Ca(2+)](i)) is critical, because calcium signaling controls diverse and vital cellular processes such as secretion, proliferation, division, gene transcription, and apoptosis. Store-operated calcium entry (SOCE) is the main mechanism through which non-excitable cells replenish and thus maintain this delicate balance. There is limited evidence which indicates that SOCE may be inhibited during mitosis, and the mechanisms leading to the presumed inhibition has not been elucidated. In the present study, we examined and compared the [Ca(2+)](i) dynamics of COS-7 cells in mitotic and non-mitotic phases with special reference paid to SOCE. Laser scanning confocal microscopy to monitor [Ca(2+)](i) dynamics revealed that SOCE was progressively inhibited in mitosis and became virtually absent during the metaphase. We used various cytoskeletal modifying drugs and immunofluorescence to assess the contribution of microtubule and actin filaments in SOCE signaling. Nocodazole treatment caused microtubule reorganization and retraction from the cell periphery that mimicked the natural mitotic microtubule remodeling that was also accompanied by SOCE inhibition. Short exposure to paclitaxel, a microtubule-stabilizing drug, bolstered SOCE, whereas long exposure resulted in microtubule disruption and SOCE inhibition. Actin-modifying drugs did not affect SOCE. These findings indicate that mitotic microtubule remodeling plays a significant role in the inhibition of SOCE during mitosis.

  3. Activation of TRPV2 and BKCa channels by the LL-37 enantiomers stimulates calcium entry and migration of cancer cells

    Science.gov (United States)

    Guéguinou, Maxime; Chourpa, Igor; Fromont, Gaëlle; Bouchet, Ana Maria; Burlaud-Gaillard, Julien; Potier-Cartereau, Marie; Roger, Sébastien; Aucagne, Vincent; Chevalier, Stéphan; Vandier, Christophe

    2016-01-01

    Expression of the antimicrobial peptide hCAP18/LL-37 is associated to malignancy in various cancer forms, stimulating cell migration and metastasis. We report that LL-37 induces migration of three cancer cell lines by activating the TRPV2 calcium-permeable channel and recruiting it to pseudopodia through activation of the PI3K/AKT pathway. Ca2+ entry through TRPV2 cooperated with a K+ efflux through the BKCa channel. In a panel of human breast tumors, the expression of TRPV2 and LL-37 was found to be positively correlated. The D-enantiomer of LL-37 showed identical effects as the L-peptide, suggesting that no binding to a specific receptor was involved. LL-37 attached to caveolae and pseudopodia membranes and decreased membrane fluidity, suggesting that a modification of the physical properties of the lipid membrane bilayer was the underlying mechanism of its effects. PMID:26993604

  4. Mechanosensitive store-operated calcium entry regulates the formation of cell polarity.

    Science.gov (United States)

    Huang, Yi-Wei; Chang, Shu-Jing; I-Chen Harn, Hans; Huang, Hui-Ting; Lin, Hsi-Hui; Shen, Meng-Ru; Tang, Ming-Jer; Chiu, Wen-Tai

    2015-09-01

    Ca(2+) -mediated formation of cell polarity is essential for directional migration which plays an important role in physiological and pathological processes in organisms. To examine the critical role of store-operated Ca(2+) entry, which is the major form of extracellular Ca(2+) influx in non-excitable cells, in the formation of cell polarity, we employed human bone osteosarcoma U2OS cells, which exhibit distinct morphological polarity during directional migration. Our analyses showed that Ca(2+) was concentrated at the rear end of cells and that extracellular Ca(2+) influx was important for cell polarization. Inhibition of store-operated Ca(2+) entry using specific inhibitors disrupted the formation of cell polarity in a dose-dependent manner. Moreover, the channelosomal components caveolin-1, TRPC1, and Orai1 were concentrated at the rear end of polarized cells. Knockdown of TRPC1 or a TRPC inhibitor, but not knockdown of Orai1, reduced cell polarization. Furthermore, disruption of lipid rafts or overexpression of caveolin-1 contributed to the downregulation of cell polarity. On the other hand, we also found that cell polarity, store-operated Ca(2+) entry activity, and cell stiffness were markedly decreased by low substrate rigidity, which may be caused by the disorganization of actin filaments and microtubules that occurs while regulating the activity of the mechanosensitive TRPC1 channel.

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

    Science.gov (United States)

    Müller, Margit S; Fox, Rebecca; Schousboe, Arne; Waagepetersen, Helle S; Bak, Lasse K

    2014-04-01

    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 Ca(2+) homeostasis, by analyzing interdependency of glycogen and store-operated Ca(2+) entry (SOCE), a mechanism in cellular signaling that maintains high endoplasmatic reticulum (ER) Ca(2+) concentration and thus provides the basis for store-dependent Ca(2+) signaling. We stimulated SOCE in primary 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 astrocytes by 1,4-dideoxy-1,4-imino-D-arabinitol, the amount of Ca(2+) loaded into ER via sarco/endoplasmic reticulum Ca(2)-ATPase (SERCA) was reduced, which suggests that SERCA pumps preferentially metabolize glycogenolytic ATP. Our study demonstrates SOCE as a novel pathway in stimulating astrocytic glycogenolysis. We also provide first evidence for a new functional role of brain glycogen, in providing local ATP to SERCA, thus establishing the bioenergetic basis for astrocytic Ca(2+) signaling. This mechanism could offer a novel explanation for the impact of glycogen on learning and memory.

  6. Myeloperoxidase modulates human platelet aggregation via actin cytoskeleton reorganization and store-operated calcium entry

    Directory of Open Access Journals (Sweden)

    Irina V. Gorudko

    2013-07-01

    Myeloperoxidase (MPO is a heme-containing enzyme released from activated leukocytes into the extracellular space during inflammation. Its main function is the production of hypohalous acids that are potent oxidants. MPO can also modulate cell signaling and inflammatory responses independently of its enzymatic activity. Because MPO is regarded as an important risk factor for cardiovascular diseases associated with increased platelet activity, we studied the effects of MPO on human platelet functional properties. Laser scanning confocal microscopy was used to reveal carbohydrate-independent MPO binding to human platelet membrane. Adding MPO to platelets did not activate their aggregation under basal conditions (without agonist. In contrast, MPO augmented agonist-induced platelet aggregation, which was not prevented by MPO enzymatic activity inhibitors. It was found that exposure of platelets to MPO leads to actin cytoskeleton reorganization and an increase in their elasticity. Furthermore, MPO evoked a rise in cytosolic Ca2+ through enhancement of store-operated Ca2+ entry (SOCE. Together, these findings indicate that MPO is not a direct agonist but rather a mediator that binds to human platelets, induces actin cytoskeleton reorganization and affects the mechanical stiffness of human platelets, resulting in potentiating SOCE and agonist-induced human platelet aggregation. Therefore, an increased activity of platelets in vascular disease can, at least partly, be provided by MPO elevated concentrations.

  7. 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.

  8. 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.

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

    Science.gov (United States)

    Shi, Zi-xuan; Rao, Wei; Wang, Huan; Wang, Nan-ding; Si, Jing-wen; Zhao, Jiao; Li, Jun-chang; Wang, Zong-ren

    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.

  10. 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.

  11. 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

  12. Involvement of transient receptor potential melastatin-8 (TRPM8) in menthol-induced calcium entry, reactive oxygen species production and cell death in rheumatoid arthritis rat synovial fibroblasts.

    Science.gov (United States)

    Zhu, Shuyan; Wang, Yuxiang; Pan, Leiting; Yang, Shuang; Sun, Yonglin; Wang, Xinyu; Hu, Fen

    2014-02-15

    Rheumatoid arthritis is most prominently characterized by synoviocyte hyperplasia which therefore serves as an important target for clinical therapy. In the present study, it was observed that menthol, the specific agonist of transient receptor potential melastatin subtype 8 (TRPM8), could induce sustained increases of cytosolic calcium concentration ([Ca(2+)]c) in synoviocytes isolated from collagen-induced arthritis rats in dose-dependent manner, which was evidently blocked by applying an extracellular Ca(2+)-free buffer. Menthol-induced [Ca(2+)]c increase was also significantly inhibited by potent TRPM8 antagonist capsazepine (CZP), indicating that this [Ca(2+)]c elevation was mostly attributed to TRPM8-mediated Ca(2+) entry. Besides, RT-PCR indeed demonstrated presence of TRPM8 in the synoviocytes. Meanwhile, it was found that menthol evoked production of intracellular reactive oxygen species, which could be abolished by Ca(2+) free solutions or CZP. Further experiments showed that menthol reduced the cell numbers and survival of synoviocytes. This reduction was associated with apoptosis as suggested by mitochondrial membrane depolarization, nuclear condensation and a caspase 3/7 apoptotic assay. Menthol-induced death and apoptosis of synoviocytes both were obviously inhibited by CZP, intracellular calcium chelator BAPTA-AM, and reactive oxygen species inhibitor diphenylene iodonium, respectively. Taken together, our data indicated that menthol resulted in synoviocyte death associated with apoptosis via calcium entry and reactive oxygen species production depending on TRPM8 activation.

  13. Involvement of intracellular calcium and src tyrosine-kinase in capacitation of cryopreserved bovine spermatozoa Participación del calcio intracelular y src tirosina quinasas en la capacitación del espermatozoide bovino criopreservado

    Directory of Open Access Journals (Sweden)

    M Satorre

    2010-06-01

    Full Text Available Increase of intracellular calcium concentration and tyrosine kinase involvement are pivotal in sperm capacitation. The aim was to determine the involvement of intracellular calcium and tyrosine kinases activity in frozen-thawed spermatozoa capacitated with heparin or quercetin. Genistein or PP2 (4-amino-5-(4-chlorophenyl-7-(t-butylpyrazolo3,4, pyrimidine were used to inhibit tyrosine kinases, and methoxyverapamil to inhibit voltage dependent calcium channels. Capacitation was determined by chlortetracycline and calcium by fl uorescence spectrophotometry. Protein tyrosine-phosphorylation was determined by western blot. Pooled frozen semen samples from four bulls were used. In presence of heparin or quercetin capacitated spermatozoa percentage and intracellular calcium were greater (PEl incremento de calcio intracelular [Ca]i y la participación de tirosina quinasa son pasos cruciales en la inducción de la capacitación. El objetivo fue determinar en espermatozoides criopreservados, la variación [Ca]i y la actividad de tirosina quinasa en la capacitación con heparina o quercetina. Genisteina o PP2(4-amino-5-(4-clorofenil-7-(t-butilpirazolo3,4,d pirimidina son inhibidores de tirosinas quinasas y de la isoforma SRC, respectivamente. Metoxiverapamil es un inhibidor de canales de calcio voltaje dependiente (CCVD. La capacitación, [Ca]i y fosforilación en tirosina se evaluaron con clorotetraciclina, espectrofl uorometría y western blot, respectivamente. El porcentaje de espermatozoides capacitados y [Ca]i fueron mayores (P<0.05 en muestras con heparina o quercetina respecto a sus controles. Genisteina o PP2 disminuyeron (P<0.05 la capacitación y el incremento de [Ca]i en las muestras con heparina pero no en las tratadas con quercetina. Genisteina o PP2 inhibió diferencialmente la fosforilación de proteínas espermáticas con ambos inductores. Methoxiverapamil bloqueó el incremento de [Ca]i sólo en la muestras con heparina. Siendo los

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

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    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

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

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    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

  16. Potassium-induced contraction in the lamb proximal urethra: Involvement of norepinephrine and different calcium entry pathways

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Pascual, A.; Costa, G.; Isla, M.; Jimenez, E.; Garcia-Sacristan, A. (Universidad Complutense de Madrid (Spain))

    1991-01-01

    The purpose of this work was to investigate the mechanisms involved in the peculiar biphasic response of the lamb urethral smooth muscle to high K+ solutions. The relative amplitude of the phasic and tonic components of the contraction and its reproducibility were dependent on the concentration of K+ used. Only concentrations higher than 80 mM (i.e., 120 mM) showed a tonic component greater in amplitude than the phasic one and manifested a tachyphylactic effect. Phentolamine (10(-6) M), prazosin (10(-6) M) and chemical denervation with 6-hydroxydopamine significantly inhibited the tonic component of the K+ (120 mM)-induced contraction, modifying its morphology. Reproducible contractions to K+ (120 mM) could be obtained in the presence of prazosin (10(-6) M) or cocaine (10(-6) M). The preparations were also shown to accumulate (3H)noradrenaline and release it upon depolarization with K+ (60 and 120 mM). Calcium removal inhibited the K+ (120 mM)-induced contraction. After addition of calcium (0.5-5 mM) the contractile activity was restored. Nifedipine (10(-6) M) and verapamil (10(-6) M) but not sodium nitroprusside (10(-6) M) significantly blocked the contractile response for calcium as well as the phasic component of the K+ contraction in calcium-containing medium. In preparations treated with prazosin (10(-6) M) the tonic component of the K+ (120 mM) contraction was more sensitive to nifedipine and removal of extracellular calcium than the phasic one.

  17. Phemindole, a synthetic di-indole derivative maneuvers the store operated calcium entry (SOCE to induce potent anti-carcinogenic activity in human triple negative breast cancer cells

    Directory of Open Access Journals (Sweden)

    Supriya eChakraborty

    2016-05-01

    Full Text Available Triple-negative breast cancer (TNBC, is a specific subtype of epithelial breast tumours that are immuno-histochemically negative for the protein expression of the estrogen receptor (ER, the progesterone receptor (PR and lack over expression/gene amplification of HER2. This subtype of breast cancers is highly metastatic, shows poor prognosis and hence represents an important clinical challenge to researchers worldwide. Thus alternative approaches of drug development for TNBC have gained utmost importance in the present times. Dietary indole and its derivatives have gained prominence as anti-cancer agents and new therapeutic approaches are being developed to target them against TNBC. But a major drawback with 3, 3’di Indolyl methane (DIM is their poor bioavailability and high effective concentration against TNBC. However the Aryl methyl ring substituted analogs of DIM display interesting anti-cancer activity in breast cancer cells. In the current study we report the synthesis of a novel synthetic aryl methyl ring substituted analog of DIM, named as Phemindole as an effective anti-tumor agent against TNBC cells. Furthermore, we enumerated that Phemindole caused ROS mediated mitochondrial-dependent apoptosis in MDAMB-231 cells. Furthermore, Phemindole mediated Store Operated Calcium Entry (SOCE retardation favored inactivation of STIM1 and henceforth activated ER stress to induce apoptosis in TNBC cells. Simultaneously, Phemindole was also found to restrict the in-vitro cell migration through its anti mitotic property and pFAK regulation. Studies extended to ex-ovo and in-vivo mice models further validated the efficacy of Phemindole. Thus our results cumulatively propose Phemindole as a new chemotherapeutic regime which might be effective to target the deadly aspects of the TNBC.

  18. Orai1 and Orai3 in Combination with Stim1 Mediate the Majority of Store-operated Calcium Entry in Astrocytes

    Science.gov (United States)

    Kwon, Jea; An, Heeyoung; Sa, Moonsun; Won, Joungha; Shin, Jeong Im

    2017-01-01

    Astrocytes are non-excitable cells in the brain and their activity largely depends on the intracellular calcium (Ca2+) level. Therefore, maintaining the intracellular Ca2+ homeostasis is critical for proper functioning of astrocytes. One of the key regulatory mechanisms of Ca2+ homeostasis in astrocytes is the store-operated Ca2+ entry (SOCE). This process is mediated by a combination of the Ca2+-store-depletion-sensor, Stim, and the store-operated Ca2+-channels, Orai and TrpC families. Despite the existence of all those families in astrocytes, previous studies have provided conflicting results on the molecular identification of astrocytic SOCE. Here, using the shRNA-based gene-silencing approach and Ca2+-imaging from cultured mouse astrocytes, we report that Stim1 in combination with Orai1 and Orai3 contribute to the major portion of astrocytic SOCE. Gene-silencing of Stim1 showed a 79.2% reduction of SOCE, indicating that Stim1 is the major Ca2+-store-depletion-sensor. Further gene-silencing showed that Orai1, Orai2, Orai3, and TrpC1 contribute to SOCE by 35.7%, 20.3%, 26.8% and 12.2%, respectively. Simultaneous gene-silencing of all three Orai subtypes exhibited a 67.6% reduction of SOCE. Based on the detailed population analysis, we predict that Orai1 and Orai3 are expressed in astrocytes with a large SOCE, whereas TrpC1 is exclusively expressed in astrocytes with a small SOCE. This analytical approach allows us to identify the store operated channel (SOC) subtype in each cell by the degree of SOCE. Our results propose that Stim1 in combination with Orai1 and Orai3 are the major molecular components of astrocytic SOCE under various physiological and pathological conditions. PMID:28243166

  19. Simultaneous determination of a novel calcium entry blocker, monatepil maleate, and its metabolites in rat plasma by means of solid-phase extraction and reversed-phase liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Kurono, M; Suzuki, K; Yoshida, K; Naruto, S

    1997-02-21

    A reversed-phase LC method with electrochemical detection is described for the simultaneous determination of monatepil maleate (AJ-2615, AJ), a novel calcium entry blocker, and its three S-oxidized metabolites in plasma. These compounds were extracted from plasma by solid-phase extraction and injected onto an ODS column. The determination limit in plasma (0.5 ml) was 10 ng/ml for AJ and 5 ng/ml for the three metabolites. The method was applied to the determination of AJ and the metabolites in rat plasma samples.

  20. 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.

  1. The polybasic lysine-rich domain of plasma membrane-resident STIM1 is essential for the modulation of store-operated divalent cation entry by extracellular calcium.

    Science.gov (United States)

    Jardin, Isaac; Dionisio, Natalia; Frischauf, Irene; Berna-Erro, Alejandro; Woodard, Geoffrey E; López, José J; Salido, Ginés M; Rosado, Juan A

    2013-05-01

    STIM1 acts as an endoplasmic reticulum Ca(2+) sensor that communicates the filling state of the intracellular stores to the store-operated channels. In addition, STIM1 is expressed in the plasma membrane, with the Ca(2+) binding EF-hand motif facing the extracellular medium; however, its role sensing extracellular Ca(2+) concentrations in store-operated Ca(2+) entry (SOCE), as well as the underlying mechanism remains unclear. Here we report that divalent cation entry stimulated by thapsigargin (TG) is attenuated by extracellular Ca(2+) in a concentration-dependent manner. Expression of the Ca(2+)-binding defective STIM1(D76A) mutant did not alter the surface expression of STIM1 but abolishes the regulation of divalent cation entry by extracellular Ca(2+). Orai1 and TRPC1 have been shown to play a major role in SOCE. Expression of the STIM1(D76A) mutant did not alter Orai1 phosphoserine content. TRPC1 silencing significantly attenuated TG-induced Mn(2+) entry. Expression of the STIM1(K684,685E) mutant impaired the association of plasma membrane STIM1 with TRPC1, as well as the regulation of TG-induced divalent cation entry by extracellular Ca(2+), which suggests that TRPC1 might be involved in the regulation of divalent cation entry by extracellular Ca(2+) mediated by plasma membrane-resident STIM1. Expression of the STIM1(D76A) or STIM1(K684,685E) mutants reduced store-operated divalent cation entry and resulted in loss of dependence on the extracellular Ca(2+) concentration, providing evidence for a functional role of plasma membrane-resident STIM1 in the regulation of store-operated divalent cation entry, which at least involves the EF-hand motif and the C-terminal polybasic lysine-rich domain.

  2. Reduction in traumatic brain injury-induced oxidative stress, apoptosis, and calcium entry in rat hippocampus by melatonin: Possible involvement of TRPM2 channels.

    Science.gov (United States)

    Yürüker, Vehbi; Nazıroğlu, Mustafa; Şenol, Nilgün

    2015-02-01

    Melatonin, which is a very effective reactive oxygen species (ROS) scavenger, acts through a direct reaction with free radicals. Ca(2+) entry induced by traumatic brain injury (TBI) has deleterious effects on human hippocampal function. TRPM2 is a Ca(2+) permeable non-selective channel in hippocampal neurons, and its activation of during oxidative stress has been linked to cell death. Despite the importance of oxidative stress in TBI, its role in apoptosis and Ca(2+) entry in TBI is poorly understood. Therefore, we tested the effects of melatonin on apoptosis, oxidative stress, and Ca(2+) entry through the TRPM2 channel in the hippocampal neurons of TBI-induced rats. Thirty-two rats were divided into the following four groups: control, melatonin, TBI, and TBI + melatonin groups. Melatonin (5 mg/kg body weight) was intraperitoneally given to animals in the melatonin group and the TBI + melatonin group after 1 h of brain trauma. Hippocampal neurons were freshly isolated from the four groups, incubated with a nonspecific TRPM2 blocker (2-aminoethyl diphenylborinate, 2-APB), and then stimulated with cumene hydroperoxide. Apoptosis, caspase-3, caspase-9, intracellular ROS production, mitochondrial membrane depolarization and intracellular free Ca(2+) ([Ca(2+)]i) values were high in the TBI group, and low in the TBI + melatonin group. The [Ca(2+)]i concentration was decreased in the four groups by 2-APB. In our TBI experimental model, TRPM2 channels were involved in Ca(2+) entry-induced neuronal death, and the negative modulation of the activity of this channel by melatonin pretreatment may account for the neuroprotective activity of TRPM2 channels against oxidative stress, apoptosis, and Ca(2+) entry.

  3. 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.

  4. Mefloquine-Induced Disruption of Calcium Homeostasis in Mammalian Cells Is Similar to That Induced by Ionomycin▿

    Science.gov (United States)

    Caridha, D.; Yourick, D.; Cabezas, M.; Wolf, L.; Hudson, T. H.; Dow, G. S.

    2008-01-01

    In previous studies, we have shown that mefloquine disrupts calcium homeostasis in neurons by depletion of endoplasmic reticulum (ER) stores, followed by an influx of external calcium across the plasma membrane. In this study, we explore two hypotheses concerning the mechanism(s) of action of mefloquine. First, we investigated the possibility that mefloquine activates non-N-methyl-d-aspartic acid receptors and the inositol phosphate 3 (IP3) signaling cascade leading to ER calcium release. Second, we compared the disruptive effects of mefloquine on calcium homeostasis to those of ionomycin in neuronal and nonneuronal cells. Ionomycin is known to discharge the ER calcium store (through an undefined mechanism), which induces capacitative calcium entry (CCE). In radioligand binding assays, mefloquine showed no affinity for the known binding sites of several glutamate receptor subtypes. The pattern of neuroprotection induced by a panel of glutamate receptor antagonists was dissimilar to that of mefloquine. Both mefloquine and ionomycin exhibited dose-related and qualitatively similar disruptions of calcium homeostasis in both neurons and macrophages. The influx of external calcium was blocked by the inhibitors of CCE in a dose-related fashion. Both mefloquine and ionomycin upregulated the IP3 pathway in a manner that we interpret to be secondary to CCE. Collectively, these data suggest that mefloquine does not activate glutamate receptors and that it disrupts calcium homeostasis in mammalian cells in a manner similar to that of ionomycin. PMID:17999964

  5. 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.

  6. 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.

  7. Homers regulate calcium entry and aggregation in human platelets: a role for Homers in the association between STIM1 and Orai1.

    Science.gov (United States)

    Jardin, Isaac; Albarrán, Letizia; Bermejo, Nuria; Salido, Ginés M; Rosado, Juan A

    2012-07-01

    Homer is a family of cytoplasmic adaptor proteins that play different roles in cell function, including the regulation of G-protein-coupled receptors. These proteins contain an Ena (Enabled)/VASP (vasodilator-stimulated phosphoprotein) homology 1 domain that binds to the PPXXF sequence motif, which is present in different Ca²⁺-handling proteins such as IP3 (inositol 1,4,5-trisphosphate) receptors and TRPC (transient receptor potential canonical) channels. In the present study we show evidence for a role of Homer proteins in the STIM1 (stromal interaction molecule 1)-Orai1 association, as well as in the TRPC1-IP3RII (type II IP3 receptor) interaction, which might be of relevance in platelet function. Treatment of human platelets with thapsigargin or thrombin results in a Ca²⁺-independent association of Homer1 with TRPC1 and IP3RII. In addition, thapsigargin and thrombin enhanced the association of Homer1 with STIM1 and Orai1 in a Ca²⁺-dependent manner. Interference with Homer function by introduction of the synthetic PPKKFR peptide into cells, which emulates the proline-rich sequences of the PPXXF motif, reduced STIM1-Orai1 and TRPC1- IP3RII associations, as compared with the introduction of the inactive PPKKRR peptide. The PPKKFR peptide attenuates thrombin-evoked Ca²⁺ entry and the maintenance of thapsigargin-induced store-operated Ca²⁺ entry. Finally, the PPKKFR peptide attenuated thrombin-induced platelet aggregation. The findings of the present study support an important role for Homer proteins in thrombin-stimulated platelet function, which is likely to be mediated by the support of agonist-induced Ca²⁺ entry.

  8. 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+.

  9. 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+.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Heart failure drug digitoxin induces calcium uptake into cells by forming transmembrane calcium channels

    OpenAIRE

    2008-01-01

    Digitoxin and other cardiac glycosides are important, centuries-old drugs for treating congestive heart failure. However, the mechanism of action of these compounds is still being elucidated. Calcium is known to potentiate the toxicity of these drugs, and we have hypothesized that digitoxin might mediate calcium entry into cells. We report here that digitoxin molecules mediate calcium entry into intact cells. Multimers of digitoxin molecules also are able to form calcium channels in pure plan...

  16. 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.

  17. Capacitive deionization of seawater

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J.C.; Fix, D.V.; Mack, G.V. [and others

    1995-10-01

    Capacitive deionization with carbon aerogel electrodes is an efficient and economical new process for removing salt and impurities from water. Carbon aerogel is a material that enables the successful purification of water because of its high surface area, optimum pore size, and low electrical resistivity. The electrodes are maintained at a potential difference of about one volt; ions are removed from the water by the imposed electrostatic field and retained on the electrode surface until the polarity is reversed. The capacitive deionization of water with a stack of carbon aerogel electrodes has been successfully demonstrated. The overall process offers advantages when compared to conventional water-purification methods, requiring neither pumps, membranes, distillation columns, nor thermal heaters. Consequently, the overall process is both robust and energy efficient. The current state of technology development, commercialization, and potential applications of this process are reviewed.

  18. 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.

  19. Ouabain, a steroid hormone that signals with slow calcium oscillations.

    Science.gov (United States)

    Aizman, O; Uhlén, P; Lal, M; Brismar, H; Aperia, A

    2001-11-06

    The plant-derived steroid, digoxin, a specific inhibitor of Na,K-ATPase, has been used for centuries in the treatment of heart disease. Recent studies demonstrate the presence of a digoxin analog, ouabain, in mammalian tissue, but its biological role has not been elucidated. Here, we show in renal epithelial cells that ouabain, in doses causing only partial Na,K-ATPase inhibition, acts as a biological inducer of regular, low-frequency intracellular calcium ([Ca(2+)](i)) oscillations that elicit activation of the transcription factor, NF-kappa B. Partial inhibition of Na,K-ATPase using low extracellular K(+) and depolarization of cells did not have these effects. Incubation of cells in Ca(2+)-free media, inhibition of voltage-gated calcium channels, inositol triphosphate receptor antagonism, and redistribution of actin to a thick layer adjacent to the plasma membrane abolished [Ca(2+)](i) oscillations, indicating that they were caused by a concerted action of inositol triphosphate receptors and capacitative calcium entry via plasma membrane channels. Blockade of ouabain-induced [Ca(2+)](i) oscillations prevented activation of NF-kappa B. The results demonstrate a new mechanism for steroid signaling via plasma membrane receptors and underline a novel role for the steroid hormone, ouabain, as a physiological inducer of [Ca(2+)](i) oscillations involved in transcriptional regulation in mammalian cells.

  20. 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.

  1. 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

  2. Efficiency of Capacitively Loaded Converters

    DEFF Research Database (Denmark)

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

    2012-01-01

    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...... 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...... polypropylene film capacitor can be the equivalent capacitive load. Because of the voltage dependent characteristic, X7R MLCC cannot be used to replace the DEAP actuator. However, this type of capacitor can be used to substitute the capacitive actuator with voltage dependent property at the development phase....

  3. Superoxide enhances Ca2+ entry through L-type channels in the renal afferent arteriole.

    Science.gov (United States)

    Vogel, Paul A; Yang, Xi; Moss, Nicholas G; Arendshorst, William J

    2015-08-01

    Reactive oxygen species regulate cardiovascular and renal function in health and disease. Superoxide participates in acute calcium signaling in afferent arterioles and renal vasoconstriction produced by angiotensin II, endothelin, thromboxane, and pressure-induced myogenic tone. Known mechanisms by which superoxide acts include quenching of nitric oxide and increased ADP ribosyl cyclase/ryanodine-mediated calcium mobilization. The effect(s) of superoxide on other calcium signaling pathways in the renal microcirculation is poorly understood. The present experiments examined the acute effect of superoxide generated by paraquat on calcium entry pathways in isolated rat afferent arterioles. The peak increase in cytosolic calcium concentration caused by KCl (40 mmol/L) was 99±14 nmol/L. The response to this membrane depolarization was mediated exclusively by L-type channels because it was abolished by nifedipine but was unaffected by the T-type channel blocker mibefradil. Paraquat increased superoxide production (dihydroethidium fluorescence), tripled the peak response to KCl to 314±68 nmol/L (Psuperoxide and not of hydrogen peroxide. Unaffected by paraquat and superoxide was calcium entry through store-operated calcium channels activated by thapsigargin-induced calcium depletion of sarcoplasmic reticular stores. Also unresponsive to paraquat was ryanodine receptor-mediated calcium-induced calcium release from the sarcoplasmic reticulum. Our results provide new evidence that superoxide enhances calcium entry through L-type channels activated by membrane depolarization in rat cortical afferent arterioles, without affecting calcium entry through store-operated entry or ryanodine receptor-mediated calcium mobilization.

  4. Calcium signalling and calcium channels: evolution and general principles.

    Science.gov (United States)

    Verkhratsky, Alexei; Parpura, Vladimir

    2014-09-15

    Calcium as a divalent cation was selected early in evolution as a signaling molecule to be used by both prokaryotes and eukaryotes. Its low cytosolic concentration likely reflects the initial concentration of this ion in the primordial soup/ocean as unicellular organisms were formed. As the concentration of calcium in the ocean subsequently increased, so did the diversity of homeostatic molecules handling calcium. This includes the plasma membrane channels that allowed the calcium entry, as well as extrusion mechanisms, i.e., exchangers and pumps. Further diversification occurred with the evolution of intracellular organelles, in particular the endoplasmic reticulum and mitochondria, which also contain channels, exchanger(s) and pumps to handle the homeostasis of calcium ions. Calcium signalling system, based around coordinated interactions of the above molecular entities, can be activated by the opening of voltage-gated channels, neurotransmitters, second messengers and/or mechanical stimulation, and as such is all-pervading pathway in physiology and pathophysiology of organisms.

  5. 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

  6. Unified capacitance modelling of MOSFETs

    Science.gov (United States)

    Johannessen, O. G.; Fjeldly, T. A.; Ytterdal, T.

    1994-01-01

    A unified physics based capacitance model for MOSFETs suitable for implementation in circuit simulators is presented. This model is based on the charge conserving, so-called Meyer-like approach proposed by Turchetti et al., and utilizes a unified charge control model to assure a continuous description of the MOSFET capacitances both above and below threshold. The capacitances associated with the model are comparable to those of the well-known BSIM model in the above-threshold regime, but it is more precise in the description of near-threshold and subthreshold behaviour. Moreover, the discontinuities at the transitions between the various regimes of operation are removed. The present modelling scheme was implemented in our circuit simulator AIM-Spice, and simulations of the dynamic behaviour of various demanding benchmark circuits clearly reveal its superiority over simulations using the simple Meyer model.

  7. 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.

  8. Control of superoxide and nitric oxide formation during human sperm capacitation.

    Science.gov (United States)

    de Lamirande, Eve; Lamothe, Geneviève; Villemure, Michèle

    2009-05-15

    We studied the modulation of superoxide anion (O(2).(-)) and nitric oxide (NO.) generation during human sperm capacitation (changes needed for the acquisition of fertility). The production of NO. (diaminofluorescein-2 fluorescence assay), but not that of O(2).(-) (luminescence assay), related to sperm capacitation was blocked by inhibitors of protein kinase C, Akt, protein tyrosine kinase, etc., but not by those of protein kinase A. Extracellular calcium (Ca(2+)) controlled O(2).(-) synthesis but extra- and intracellular Ca(2+) regulated NO. formation. Zinc inhibited capacitation and formation of O(2).(-) and NO.. Zinc chelators (TPEN and EDTA) and sulfhydryl-targeted compounds (diamide and N-ethylmaleimide) stimulated capacitation and formation of O(2).(-) and NO.; superoxide dismutase (SOD) and nitric oxide synthase inhibitor (L-NMMA) prevented these events. Diphenyliodonium (flavoenzyme inhibitor) blocked capacitation and related O(2).(-) synthesis but promoted NO. formation, an effect canceled by SOD and L-NMMA. NADPH induced capacitation and NO. (but not O(2).(-)) synthesis and these events were blocked by L-NMMA and not by SOD. Integration of these data on O(2).(-) and NO. production during capacitation reinforces the concept that a complex, but flexible, network of factors is involved and probably is associated with rescue mechanisms, so that spermatozoa can achieve successful fertilization.

  9. 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

  10. 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.

  11. The ins and outs of mitochondrial calcium.

    Science.gov (United States)

    Finkel, Toren; Menazza, Sara; Holmström, Kira M; Parks, Randi J; Liu, Julia; Sun, Junhui; Liu, Jie; Pan, Xin; Murphy, Elizabeth

    2015-05-22

    Calcium is thought to play an important role in regulating mitochondrial function. Evidence suggests that an increase in mitochondrial calcium can augment ATP production by altering the activity of calcium-sensitive mitochondrial matrix enzymes. In contrast, the entry of large amounts of mitochondrial calcium in the setting of ischemia-reperfusion injury is thought to be a critical event in triggering cellular necrosis. For many decades, the details of how calcium entered the mitochondria remained a biological mystery. In the past few years, significant progress has been made in identifying the molecular components of the mitochondrial calcium uniporter complex. Here, we review how calcium enters and leaves the mitochondria, the growing insight into the topology, stoichiometry and function of the uniporter complex, and the early lessons learned from some initial mouse models that genetically perturb mitochondrial calcium homeostasis.

  12. 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. PMID:22993694

  13. Entry at Venus

    Science.gov (United States)

    Venkatapathy, Ethiraj; Smith, Brandon

    2016-01-01

    This is lecture to be given at the IPPW 2016, as part of the 2 day course on Short Course on Destination Venus: Science, Technology and Mission Architectures. The attached presentation material is intended to be introduction to entry aspects of Venus in-situ robotic missions. The presentation introduces the audience to the aerodynamic and aerothermodynamic aspects as well as the loads, both aero and thermal, generated during entry. The course touches upon the system design aspects such as TPS design and both high and low ballistic coefficient entry system concepts that allow the science payload to be protected from the extreme entry environment and yet meet the mission objectives.

  14. Calcium supplements

    Science.gov (United States)

    ... do not help. Always tell your provider and pharmacist if you are taking extra calcium. Calcium supplements ... 2012:chap 251. The National Osteoporosis Foundation (NOF). Clinician's Guide to prevention and treatment of osteoporosis . National ...

  15. 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.

  16. Double entry bookkeeping vs single entry bookkeeping

    Directory of Open Access Journals (Sweden)

    Ileana Andreica

    2016-11-01

    Full Text Available Abstract: A financial management eficiently begin, primarily, with an accounting record kept in the best possible conditions, this being conditioned on the adoption of a uniform forms, rational, clear and simple accounting. Throughout history, there have been known two forms of accounting: the simple and double entry. Romanian society after 1990 underwent a substantial change in social structure, the sector on which put a great emphasis being private, that of small manufacturers, peddler, freelance, who work independently and authorized or as associative form (family enterprises, various associations (owners, tenants, etc., liberal professions, etc.. They are obliged to keep a simple bookkeeping, because they have no juridical personality. Companies with legal personality are required to keep double entry bookkeeping; therefore, knowledge and border demarcation between the two forms of organisation of accounting is an essential. The material used for this work is mainly represented by the financial and accounting documents, by the analysis of the economic, by legislative updated sources, and as the method was used the comparison method, using hypothetical data, in case of an authorized individual and a legal entity. Based on the chosen material, an authorized individual (who perform single entry accounting system and a juridical entity (who perform double entry accounting system were selected comparative case studies, using hypothetical data, were analysed advantages and disadvantages in term of fiscal, if using two accounting systems, then were highlighted some conclusion that result.

  17. Capacitance enhancement via electrode patterning

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Tuan A.; Striolo, Alberto, E-mail: a.striolo@ucl.ac.uk [School of Chemical, Biological and Materials Engineering, The University of Oklahoma, Norman, Oklahoma 73019 (United States); Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    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.

  18. 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

  19. Capacitance enhancement via electrode patterning

    Science.gov (United States)

    Ho, Tuan A.; Striolo, Alberto

    2013-11-01

    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.

  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. Compact monolithic capacitive discharge unit

    Science.gov (United States)

    Roesler, Alexander W.; Vernon, George E.; Hoke, Darren A.; De Marquis, Virginia K.; Harris, Steven M.

    2007-06-26

    A compact monolithic capacitive discharge unit (CDU) is disclosed in which a thyristor switch and a flyback charging circuit are both sandwiched about a ceramic energy storage capacitor. The result is a compact rugged assembly which provides a low-inductance current discharge path. The flyback charging circuit preferably includes a low-temperature co-fired ceramic transformer. The CDU can further include one or more ceramic substrates for enclosing the thyristor switch and for holding various passive components used in the flyback charging circuit. A load such as a detonator can also be attached directly to the CDU.

  2. 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.

  3. [Bone and Nutrition. Vitamin D independent calcium absorption].

    Science.gov (United States)

    Masuyama, Ritsuko

    2015-07-01

    Vitamin D endocrine system is required for normal calcium and bone homeostasis. Trans-epithelial calcium absorption is initiated with calcium entry into the intestinal epithelial cells from luminal fluid through calcium permeable channels, and those expressions are strongly supported by vitamin D action. On the other hands, dietary treatment, mineral supplementation or restriction, successfully improves intestinal calcium absorption in global vitamin D receptor knock-out (VDR KO) mice, though vitamin D dependent active transport pathway is lacking. Dietary rescue of intestinal calcium absorption provided a positive calcium balance in this mouse model, and suggested that the major role of vitamin D function on calcium homeostasis was considered to be intestinal active absorption. To elucidate the entire process of intestinal calcium absorption, vitamin D independent calcium transport system was characterized into either trans-cellular or para-cellular process.

  4. Calcium channel antagonists in hypertension.

    Science.gov (United States)

    Ambrosioni, E; Borghi, C

    1989-02-01

    The clinical usefulness of calcium entry-blockers for the treatment of high blood pressure is related to their capacity to act upon the primary hemodynamic derangement in hypertension: the increased peripheral vascular resistance. They can be used alone or in combination with other antihypertensive agents for the treatment of various forms of hypertensive disease. The calcium entry-blockers appear to be the most useful agents for the treatment of hypertension in the elderly and for the treatment of hypertension associated with ischemic heart disease, pulmonary obstructive disease, peripheral vascular disease, and supraventricular arrhythmias. They are effective in reducing blood pressure in pregnancy-associated hypertension and must be considered as first-line therapy for the treatment of hypertensive crisis.

  5. 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

  6. 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...

  7. Locating Depots for Capacitated Vehicle Routing

    DEFF Research Database (Denmark)

    Gørtz, Inge Li; Nagarajan, Viswanath

    2016-01-01

    We study a location-routing problem in the context of capacitated vehicle routing. The input to the k-location capacitated vehicle routing problem (k-LocVRP) consists of a set of demand locations in a metric space and a fleet of k identical vehicles, each of capacity Q. The objective is to locate k...

  8. Novel RF-MEMS capacitive switching structures

    NARCIS (Netherlands)

    Rottenberg, X.; Jansen, H.; Fiorini, P.; De Raedt, W.; Tilmans, H.A.C.

    2002-01-01

    This paper reports on novel RF-MEMS capacitive switching devices implementing an electrically floating metal layer covering the dielectric to ensure intimate contact with the bridge in the down state. This results in an optimal switch down capacitance and allows optimisation of the down/up capacitan

  9. 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.

  10. 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

  11. Capacitively-coupled chopper amplifiers

    CERN Document Server

    Fan, Qinwen; Huijsing, Johan H

    2017-01-01

    This book describes the concept and design of the capacitively-coupled chopper technique, which can be used in precision analog amplifiers. Readers will learn to design power-efficient amplifiers employing this technique, which can be powered by regular low supply voltage such as 2V and possibly having a +\\-100V input common-mode voltage input. The authors provide both basic design concepts and detailed design examples, which cover the area of both operational and instrumentation amplifiers for multiple applications, particularly in power management and biomedical circuit designs. Discusses basic working principles and details of implementation for proven designs; Includes a diverse set of applications, along with measurement results to demonstrate the effectiveness of the technique; Explains advantages and drawbacks of the technique, given particular circumstances.

  12. Capacitance Measurement Methods for Integrated Sensor Applications

    Directory of Open Access Journals (Sweden)

    Alireza Hassanzadeh

    2013-09-01

    Full Text Available In this paper different measurement methods that have been used for integrated capacitance measurement are reviewed and their advantage and disadvantages are discussed. For the designers of high accuracy on chip integrated circuits for capacitive sensors, it is important to know which method will provide the best approach for high accuracy, small chip area and power consumption especially for array sensors. These methods include on chip capacitive sensor and transducer measurement techniques that have been implemented for low value capacitance evaluations using CMOS technology. After the best structure is known the designer can optimize the chip for specific application. Voltage mode and current mode, linear and switched mode techniques are reviewed and a useful comparison table comparing all figures of merit including accuracy, range of measurement, chip area, speed and complexity is provided. The provided comparison table can be used as a reference for analog designers in the design of high accuracy integrated capacitive sensor interface

  13. Evaluation of the antihypertensive effect of barnidipine, a dihydropyridine calcium entry blocker, as determined by the ambulatory blood pressure level averaged for 24 h, daytime, and nighttime. Barnidipine Study Group.

    Science.gov (United States)

    Imai, Y; Abe, K; Nishiyama, A; Sekino, M; Yoshinaga, K

    1997-12-01

    We evaluated the effect of barnidipine, a dihydropyridine calcium antagonist, administered once daily in the morning in a dose of 5, 10, or 15 mg on ambulatory blood pressure (BP) in 34 patients (51.3+/-9.6 years). Hypertension was diagnosed based on the clinic BP. The patients were classified into groups according to the ambulatory BP: group 1, dippers with true hypertension; group 2, nondippers with true hypertension; group 3, dippers with false hypertension; and Group 4, nondippers with false hypertension. Barnidipine reduced the clinic systolic BP (SBP) and diastolic BP (DBP) in all groups and significantly reduced the average 24 h ambulatory BP (133.0+/-16.5/90.7+/-12.3 mm Hg v 119.7+/-13.7/81.8+/-10.3 mm Hg, P Barnidipine significantly reduced the daytime ambulatory SBP in groups 1, 2, and 3, but not in group 4, and significantly reduced daytime ambulatory DBP in group 1 but not in groups 2, 3, and 4. Barnidipine significantly reduced the nighttime ambulatory SBP only in group 2 and the nighttime ambulatory DBP in groups 2 and 4. Once-a-day administration of barnidipine influenced 24 h BP on true hypertensives (the ratio of the trough to peak effect > 50%), but had minimal effect on low BP such as the nocturnal BP in dippers and the ambulatory BP in false hypertensives. These findings suggest that barnidipine can be used safely in patients with isolated clinic ("white coat") hypertension and in those with dipping patterns of circadian BP variation whose nocturnal BP is low before treatment.

  14. Shuttle entry guidance

    Science.gov (United States)

    Harpold, J. C.; Graves, C. A., Jr.

    1978-01-01

    This paper describes the design of the entry guidance for the Space Shuttle Orbiter. This guidance provides the steering commands for trajectory control from initial penetration of the earth's atmosphere until the terminal area guidance is activated at an earth-relative speed of 2500 fps. At this point, the Orbiter is at a distance of about 50 nmi from the runway threshold, and at an altitude of about 80,000 ft. The entry guidance design is based on an analytic solution of the equations of motion defining the drag acceleration profile that meets the terminal criteria of the entry flight while maintaining the flight within systems and operational constraints. Guidance commands, which are based on a control law that ensures damping of oscillatory type trajectory motion, are computed to steer the Orbiter to this drag acceleration profile.

  15. Sperm capacitation in the porcine oviduct.

    Science.gov (United States)

    Tienthai, P; Johannisson, A; Rodriguez-Martinez, H

    2004-01-01

    In vitro studies suggests that sperm capacitation occurs in the sperm reservoir (SR) of the pig, with spermatozoa progressing towards the ampullary-isthmic junction (AIJ) around ovulation as a consequence of capacitation/hyperactivation. In contrast, in vivo studies are scarce. Consequently, we determined the degree of capacitation in boar spermatozoa that were retrieved from the SR of sows at well-defined periods of spontaneous standing oestrus, namely pre-, peri- and post-ovulation, using flow cytometry of Merocyanine-540/Yo-Pro-1-loaded spermatozoa. SR-spermatozoa retrieved and incubated in non-capacitating medium (bicarbonate-free mBO [mBO-]) were largely viable (70-85%) and uncapacitated (69-73%), irrespective of the stage of oestrus considered. Those undergoing capacitation were a minor proportion (1-5%) during pre- and peri-ovulation, but they significantly increased (14%) in post-ovulation oestrus. To clarify whether these SR-spermatozoa were able to undergo capacitation under stimuli, sperm aliquots were challenged in vitro either by incubation in a bicarbonate-rich medium (capacitation medium, mBO+), then further in mBO+ with 20% (v/v) of in vivo collected homologous pre-ovulatory isthmic oviductal fluid (IOF), or incubation with hyaluronan (HA, 500 microg/ml). Exposure to mBO+ significantly increased the sub-population of capacitated spermatozoa from the pre- and peri-ovulation SR, indicating that the uncapacitated SR-spermatozoa were responsive to the effector/inducer bicarbonate at levels recorded in peri-ovulatory AIJ/ampulla in vivo. While addition of IOF or HA to SR-spermatozoa incubated in capacitating medium (mBO+) maintained sperm viability without obviously inducing capacitation in pre- or peri-ovulatory SR-spermatozoa, they significantly increased these percentages during post-ovulation, when compared to baseline values of control incubations (mBO-). The results suggest that massive sperm capacitation does not occur in vivo in the porcine SR

  16. Calcium in diet

    Science.gov (United States)

    ... D is needed to help your body use calcium. Milk is fortified with vitamin D for this reason. ... of calcium dietary supplements include calcium citrate and calcium carbonate. Calcium citrate is the more expensive form of ...

  17. 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.

  18. Effect of surface asperities on the capacitances of capacitive RF MEMS switches

    Science.gov (United States)

    Chen, Zhiqiang; Tian, Wenchao; Zhang, Xiaotong

    2017-03-01

    The effects of surface asperities on the up- and down-state capacitances of the capacitive radio frequency (RF) micro electromechanical system (MEMS) switches were studied in this paper based on the single asperity model and statics. The research results demonstrated that surface asperities effects on the up-state capacitance could be neglected, whereas surface asperities must be taken into consideration at the down-state position in the RF MEMS switches because the surface asperities significantly affected the down-state capacitance. The down-state capacitance typically decreased as the root mean square (RMS) roughness and asperity radius increased. The down-state capacitance was approximately 26% of the theoretical value when the RMS roughness was 20 nm, and 32% of the theoretical value when the asperity radius was 100 nm. The experimental results were in good agreement with the simulation results.

  19. Capacitive Cells for Dielectric Constant Measurement

    Science.gov (United States)

    Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco

    2015-01-01

    A simple capacitive cell for dielectric constant measurement in liquids is presented. As an illustrative application, the cell is used for measuring the degradation of overheated edible oil through the evaluation of their dielectric constant.

  20. 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

  1. 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.

  2. 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

  3. 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....

  4. The role of actin in capacitation-related signaling: an in silico and in vitro study

    Directory of Open Access Journals (Sweden)

    Lucidi Pia

    2011-03-01

    Full Text Available Abstract Background The signalling cascades involved in many biological processes require the coordination of different subcellular districts. It is the case of the pathways involved in spermatozoa acquisition of fertilizing ability (the so called "capacitation". In the present work the coordination of subcellular signalling, during the boar sperm capacitation, was studied by a computational and experimental approach. As first the biological network representing all the molecular interactions involved in capacitation was build and analyzed, then, an experimental set up was carried out to confirm the computational model-based prediction. Results The analysis of computational model pointed out that the "actin polymerization" node had some important and unique features: - it is one of the most connected nodes, - it links in a specific manner all the intracellular compartments, - its removal from the network did not affect the global network topology but caused the loss of five important nodes (and among them the "plasma membrane" and "outer acrosome membrane" fusion. Thus, it was suggested that actin polymerization could be involved in the signaling coordination of different subcellular districts, and that its functional ablation could compromise spermatozoa ability to complete the capacitation (while the main signaling pathway remained unaffected. The experiments, carried out inhibiting the actin polymerization in capacitating boar spermatozoa by the administration of cytocalasin D (CD, demonstrated that the CD treatment inhibited spermatozoa ability to reach the full fertilizing ability, while, the examined signaling pathways (membrane acquisition of chlortetracicline pattern C, protein tyrosine phosphorylation, phospholipase C-γ1 relocalization, intracellular calcium response to zonae pellucidae remained effective, thus, confirming the model-based hypothesis. Conclusions The model based-hypothesis was confirmed by the reported data obtained

  5. 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.

  6. 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...

  7. 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.

  8. 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

  9. 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.

  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. 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.

  12. 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.

  13. 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. ...

  14. Role of the oviduct in sperm capacitation.

    Science.gov (United States)

    Rodriguez-Martinez, H

    2007-09-01

    Following insemination of spermatozoa pre-ovulation, the mammalian oviduct ensures, by the formation of a functional sperm reservoir (SR), that suitable (low) numbers of viable and potentially fertile spermatozoa are available for fertilization at the ampullary isthmic junction (AIJ). As ovulation approaches, a proportion of the SR-stored spermatozoa is continuously distributed towards the AIJ and individually activated leading to step-wise capacitation and the attainment of hyperactivated motility. This paper reviews in vivo changes in the intra-luminal milieu of the oviduct of pigs and cows, in particular the SR and the AIJ which relate to the modulation of sperm capacitation around spontaneous ovulation. In vivo, most viable spermatozoa in the pre-ovulatory SR are uncapacitated. Capacitation rates significantly increase after ovulation, apparently not massively but concurrent with the individual, continuous sperm dislocation from the SR. Bicarbonate, whose levels differ between the SR and the AIJ, appears as the common primary effector of the membrane destabilizing changes that encompasses the first stages of capacitation. Sperm activation can be delayed or even reversed by co-incubation with membrane proteins of the tubal lining, isthmic fluid or specific tubal glycosaminoglycans, such as hyaluronan. Although the pattern of response to in vitro induction of sperm activation - capacitation in particular - is similar for all spermatozoa, the capacity and speed of the response is very individual. Such diversity in responsiveness among spermatozoa insures full sperm viability before ovulation and the presence of spermatozoa at different stages of capacitation at the AIJ, thus maximizing the chances of normal fertilization.

  15. Calcium Test

    Science.gov (United States)

    ... if a person has symptoms of a parathyroid disorder , malabsorption , or an overactive thyroid. A total calcium level is often measured as part of a routine health screening. It is included in the comprehensive metabolic panel (CMP) and the basic metabolic panel (BMP) , ...

  16. Calcium Carbonate

    Science.gov (United States)

    ... doctor if you have or have ever had kidney disease or stomach conditions.tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking calcium carbonate, call your doctor.

  17. Capacitance sensor for automatic soil retreat measurements

    Institute of Scientific and Technical Information of China (English)

    GU Jun; YANG Juan; YIN Wu-liang; WANG Chao; WANG Hua-xiang; LIU Ze; CHENG Su-sen

    2008-01-01

    To continuously monitor the soil retreat due to erosion in field, provide valuable information about the erosion processes and overcome the disadvantages of inefficiency, high time-consumption and labor-intensity of existing methods, this paper describes a novel capacitance sensor for measuring the soil retreat. A capaci-tance sensor based probe is proposed, which can measure the depth of the soil around it automatically and the data can be recorded by a data logger. Experimental results in the lab verify its usefulness.

  18. 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.

  19. 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...

  20. Regulation of voltage gated calcium channels by GPCRs and post-translational modification.

    Science.gov (United States)

    Huang, Junting; Zamponi, Gerald W

    2016-10-18

    Calcium entry via voltage gated calcium channels mediates a wide range of physiological functions, whereas calcium channel dysregulation has been associated with numerous pathophysiological conditions. There are myriad cell signaling pathways that act on voltage gated calcium channels to fine tune their activities and to regulate their cell surface expression. These regulatory mechanisms include the activation of G protein-coupled receptors and downstream phosphorylation events, and their control over calcium channel trafficking through direct physical interactions. Calcium channels also undergo post-translational modifications that alter both function and density of the channels in the plasma membrane. Here we focus on select aspects of these regulatory mechanisms and highlight recent developments.

  1. 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...

  2. 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

  3. 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.

  4. Comparison of piezoresistive and capacitive ultrasonic transducers

    Science.gov (United States)

    Neumann, John J.; Greve, David W.; Oppenheim, Irving J.

    2004-07-01

    MEMS ultrasonic transducers for flaw detection have heretofore been built as capacitive diaphragm-type devices. A diaphragm forms a moveable electrode, placed at a short gap from a stationary electrode, and diaphragm movement has been detected by capacitance change. Although several research teams have successfully demonstrated that technology, the detection of capacitance change is adversely affected by stray and parasitic capacitances, limiting the sensitivity of such transducers and typically requiring relatively large diaphragm areas. We describe the design and fabrication of what to our knowledge is the first CMOS-MEMS ultrasonic phased array transducer using piezoresistive strain sensing. Piezoresistors have been patterned within the diaphragms, and diaphragm movement creates bending strain which is detected by a bridge circuit, for which conductor losses will be less significant. The prospective advantage of such piezoresistive transducers is that sufficient sensitivity may be achieved with very small diaphragms. We compare transducer response under fluid-coupled ultrasonic excitation and report the experimental gauge factor for the piezoresistors. We also discuss the phased array performance of the transducer in sensing the direction of an incoming wave.

  5. 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...

  6. Investigation on a Novel Capacitive Electrode for Geophysical Surveys

    Directory of Open Access Journals (Sweden)

    Zhiyu Wang

    2016-01-01

    Full Text Available Nonpolarizable electrodes are applied widely in the electric field measurement for geophysical surveys. However, there are two major problems: (1 systematic errors caused by poor electrical contact in the high resistive terrains and (2 environmental damage associated with using nonpolarizable electrodes. A new alternative structure of capacitive electrode, which is capable of sensing surface potential through weak capacitive coupling, is presented to solve the above problems. A technique is introduced to neutralize distributed capacitance and input capacitance of the detection circuit. With the capacitance neutralization technique, the transmission coefficient of capacitive electrode remains stable when environmental conditions change. The simulation and field test results indicate that the new capacitive electrode has an operating bandwidth range from 0.1 Hz to 1 kHz. The capacitive electrodes have a good prospect of the applications in geophysical prospecting, especially in resistive terrains.

  7. 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.

  8. Membrane fusion during poxvirus entry.

    Science.gov (United States)

    Moss, Bernard

    2016-12-01

    Poxviruses comprise a large family of enveloped DNA viruses that infect vertebrates and invertebrates. Poxviruses, unlike most DNA viruses, replicate in the cytoplasm and encode enzymes and other proteins that enable entry, gene expression, genome replication, virion assembly and resistance to host defenses. Entry of vaccinia virus, the prototype member of the family, can occur at the plasma membrane or following endocytosis. Whereas many viruses encode one or two proteins for attachment and membrane fusion, vaccinia virus encodes four proteins for attachment and eleven more for membrane fusion and core entry. The entry-fusion proteins are conserved in all poxviruses and form a complex, known as the Entry Fusion Complex (EFC), which is embedded in the membrane of the mature virion. An additional membrane that encloses the mature virion and is discarded prior to entry is present on an extracellular form of the virus. The EFC is held together by multiple interactions that depend on nine of the eleven proteins. The entry process can be divided into attachment, hemifusion and core entry. All eleven EFC proteins are required for core entry and at least eight for hemifusion. To mediate fusion the virus particle is activated by low pH, which removes one or more fusion repressors that interact with EFC components. Additional EFC-interacting fusion repressors insert into cell membranes and prevent secondary infection. The absence of detailed structural information, except for two attachment proteins and one EFC protein, is delaying efforts to determine the fusion mechanism.

  9. 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.

  10. 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.

  11. 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.

  12. Water Entry of Projectiles

    Science.gov (United States)

    Truscott, Tadd T.; Epps, Brenden P.; Belden, Jesse

    2014-01-01

    The free-surface impact of solid objects has been investigated for well over a century. This canonical problem is influenced by many physical parameters, including projectile geometry, material properties, fluid properties, and impact parameters. Through advances in high-speed imaging and visualization techniques, discoveries about the underlying physics have improved our understanding of these phenomena. Improvements to analytical and numerical models have led to critical insights into cavity formation, the depth and time of pinch-off, forces, and trajectories for myriad different impact parameters. This topic spans a wide range of regimes, from low-speed entry phenomena dominated by surface tension to high-speed ballistics, for which cavitation is important. This review surveys experimental, theoretical, and numerical studies over this broad range, utilizing canonical images where possible to enhance intuition and insight into the rich phenomena.

  13. Shuttle entry guidance revisited

    Science.gov (United States)

    Mease, Kenneth D.; Kremer, Jean-Paul

    1992-01-01

    The Shuttle entry guidance concept is reviewed which is aimed at tracking a reference drag trajectory that leads to the specified range and velocity for the initiation of the terminal energy management phase. An approximate method of constructing the domain of attraction is proposed, and its validity is ascertained by simulation. An alternative guidance law yielding global exponential tracking in the absence of control saturation is derived using a feedback linearization method. It is noted that the alternative guidance law does not improve on the stability and performance of the current guidance law, for the operating domain and control capability of the Shuttle. It is suggested that the new guidance law with a larger operating domain and increased lift-to-drag capability would be superior.

  14. Shuttle entry guidance revisited

    Science.gov (United States)

    Mease, Kenneth D.; Kremer, Jean-Paul

    1992-08-01

    The Shuttle entry guidance concept is reviewed which is aimed at tracking a reference drag trajectory that leads to the specified range and velocity for the initiation of the terminal energy management phase. An approximate method of constructing the domain of attraction is proposed, and its validity is ascertained by simulation. An alternative guidance law yielding global exponential tracking in the absence of control saturation is derived using a feedback linearization method. It is noted that the alternative guidance law does not improve on the stability and performance of the current guidance law, for the operating domain and control capability of the Shuttle. It is suggested that the new guidance law with a larger operating domain and increased lift-to-drag capability would be superior.

  15. Heart failure drug digitoxin induces calcium uptake into cells by forming transmembrane calcium channels.

    Science.gov (United States)

    Arispe, Nelson; Diaz, Juan Carlos; Simakova, Olga; Pollard, Harvey B

    2008-02-19

    Digitoxin and other cardiac glycosides are important, centuries-old drugs for treating congestive heart failure. However, the mechanism of action of these compounds is still being elucidated. Calcium is known to potentiate the toxicity of these drugs, and we have hypothesized that digitoxin might mediate calcium entry into cells. We report here that digitoxin molecules mediate calcium entry into intact cells. Multimers of digitoxin molecules also are able to form calcium channels in pure planar phospholipid bilayers. These digitoxin channels are blocked by Al(3+) and La(3+) but not by Mg(2+) or the classical l-type calcium channel blocker, nitrendipine. In bilayers, we find that the chemistry of the lipid affects the kinetics of the digitoxin channel activity, but not the cation selectivity. Antibodies against digitoxin promptly neutralize digitoxin channels in both cells and bilayers. We propose that these digitoxin calcium channels may be part of the mechanism by which digitoxin and other active cardiac glycosides, such as digoxin, exert system-wide actions at and above the therapeutic concentration range.

  16. 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.

  17. 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...... 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...... of the routes in the PCVRP solution. This paper develops an exact branch-and-cut-and-price (BCP) algorithm for the PCVRP. At the pricing stage, elementary routes can be computed in pseudo-polynomial time in the PCVRP, unlike in the CVRP. We have therefore implemented pricing algorithms that generate only...

  18. 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.

  19. 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.

  20. Regucalcin is widely distributed in the male reproductive tract and exerts a suppressive effect on in vitro sperm capacitation in the water buffalo (Bubalus bubalis).

    Science.gov (United States)

    Pillai, Harikrishna; Shende, Ashish Mukunda; Parmar, Mehtab Sing; A, Anjaneya; L, Sreela; Kumaresan, Arumugam; G, Taru Sharma; Bhure, Sanjeev Kumar

    2017-03-01

    Regucalcin is a multi-functional, calcium-binding protein with roles in calcium homeostasis, apoptosis, cell proliferation, and free radical neutralization. Regucalcin is broadly expressed in the male reproductive organs of rat and bovine; here, we report its expression in the reproductive tract of male buffalo-especially in testis, epididymis, seminal vesicle, prostate, and bulbourethral gland of buffalo-as analyzed by real-time PCR, Western blot, and immunolocalization. Regucalcin degradation in seminal plasma, despite its high abundance in vesicular fluid, was demonstrated using recombinant regucalcin co-incubated with buffalo seminal plasma. This depletion of regucalcin appears to be related to its suppressive effect on in vitro sperm capacitation, observed using the chlortetracycline assay after treating buffalo spermatozoa with recombinant protein. Indeed, addition of recombinant regucalcin to capacitating media significantly reduced (P < 0.05) the percentage of capacitated spermatozoa to 6.1 ± 0.6 from 36.4 ± 1.8 in the untreated group. Taken together, the wide distribution of regucalcin in male buffaloes, versus its degradation in the seminal plasma and suppressive effects on in vitro capacitation of spermatozoa, indicate its possible anti-capacitation role in the reproductive tract. Mol. Reprod. Dev. 84: 212-221, 2017. © 2016 Wiley Periodicals, Inc.

  1. Evaluation of a Capacitance Scaling System

    Science.gov (United States)

    2007-01-01

    2009 at 11:32 from IEEE Xplore . Restrictions apply. Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the...Downloaded on January 30, 2009 at 11:32 from IEEE Xplore . Restrictions apply. 2162 IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 56, NO. 6...30, 2009 at 11:32 from IEEE Xplore . Restrictions apply. AVRAMOV-ZAMUROVIC et al.: EVALUATION OF A CAPACITANCE SCALING SYSTEM 2163 measured to vary by

  2. THERMAL DRIFT CHARACTERISTICS OF CAPACITIVE PRESSURE SENSORS

    OpenAIRE

    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...

  3. A new desalination technique using capacitive deionization

    Science.gov (United States)

    Rostamy, Mohammad Sajjad; Khashechi, Morteza; Pipelzadeh, Ehsan; desalination Team

    2016-11-01

    Capacitive deionization (CDI) is an emerging energy efficient, low pressure and low capital intensive desalination process where ions are separated by a pure electrostatic force imposed by a small bias potential as low as 1 V That funded by an external Renewable (Solar) power supply to materials with high specific surface area. The main objective of this configuration is to separate the cation and anions on oppositely charged electrodes. Various electrode materials have been developed in the past, which have suffered from instability and lack of performance. Preliminary experimental results using carbon black, graphite powder, graphene ∖graphite ∖PTFE (Active ∖Conductive ∖binder), show that the graphene reduced via urea method is a suitable method to develop CDI electrode materials with capacitance as high as 52.2 mg/g for free standing graphene electrode. The focus of these studies has been mainly on developing electrodes with high specific surface area, high capacitance, excellent electronic conductivity and fast charge discharge cycles for desalination. Although some progress has been made, production of efficient and stable carbon based electrode materials for large scale desalination has not been fully realized.

  4. 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.

  5. 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.

  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. 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.

  8. CaV1.2 calcium channels: just cut out to be regulated?

    Science.gov (United States)

    Groth, Rachel D; Tirko, Natasha N; Tsien, Richard W

    2014-06-04

    Tight regulation of calcium entry through the L-type calcium channel CaV1.2 ensures optimal excitation-response coupling. In this issue of Neuron, Michailidis et al. (2014) demonstrate that CaV1.2 activity triggers negative feedback regulation through proteolytic cleavage of the channel within the core of the pore-forming subunit.

  9. Store-Operated Calcium Channels.

    Science.gov (United States)

    Prakriya, Murali; Lewis, Richard S

    2015-10-01

    Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca(2+) from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca(2+) sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca(2+) from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca(2+) depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease.

  10. 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.

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

    Science.gov (United States)

    Nandi, Pinki; Ghosh, Swatilekha; Jana, Kuladip; Sen, Parimal C

    2012-01-01

    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.

  12. 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.

  13. 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.

  14. 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...

  15. 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.

  16. Orion Entry Handling Qualities Assessments

    Science.gov (United States)

    Bihari, B.; Tiggers, M.; Strahan, A.; Gonzalez, R.; Sullivan, K.; Stephens, J. P.; Hart, J.; Law, H., III; Bilimoria, K.; Bailey, R.

    2011-01-01

    The Orion Command Module (CM) is a capsule designed to bring crew back from the International Space Station (ISS), the moon and beyond. The atmospheric entry portion of the flight is deigned to be flown in autopilot mode for nominal situations. However, there exists the possibility for the crew to take over manual control in off-nominal situations. In these instances, the spacecraft must meet specific handling qualities criteria. To address these criteria two separate assessments of the Orion CM s entry Handling Qualities (HQ) were conducted at NASA s Johnson Space Center (JSC) using the Cooper-Harper scale (Cooper & Harper, 1969). These assessments were conducted in the summers of 2008 and 2010 using the Advanced NASA Technology Architecture for Exploration Studies (ANTARES) six degree of freedom, high fidelity Guidance, Navigation, and Control (GN&C) simulation. This paper will address the specifics of the handling qualities criteria, the vehicle configuration, the scenarios flown, the simulation background and setup, crew interfaces and displays, piloting techniques, ratings and crew comments, pre- and post-fight briefings, lessons learned and changes made to improve the overall system performance. The data collection tools, methods, data reduction and output reports will also be discussed. The objective of the 2008 entry HQ assessment was to evaluate the handling qualities of the CM during a lunar skip return. A lunar skip entry case was selected because it was considered the most demanding of all bank control scenarios. Even though skip entry is not planned to be flown manually, it was hypothesized that if a pilot could fly the harder skip entry case, then they could also fly a simpler loads managed or ballistic (constant bank rate command) entry scenario. In addition, with the evaluation set-up of multiple tasks within the entry case, handling qualities ratings collected in the evaluation could be used to assess other scenarios such as the constant bank angle

  17. Tunable Lowpass Filter with RF MEMS Capacitance and Transmission Line

    Directory of Open Access Journals (Sweden)

    Shimul C. Saha

    2012-01-01

    Full Text Available We have presented an RF MEMS tuneable lowpass filter. Both distributed transmission lines and RF MEMS capacitances were used to replace the lumped elements. The use of RF MEMS capacitances gives the flexibility of tuning the cutoff frequency of the lowpass filter. We have designed a low-pass filter at 9–12 GHz cutoff frequency using the theory of stepped impedance transmission lines. A prototype of the filter has been fabricated using parallel plate capacitances. The variable shunt capacitances are formed by a combination of a number of parallel plate RF MEMS capacitances. The cutoff frequency is tuned from C to X band by actuating different combinations of parallel capacitive bridges. The measurement results agree well with the simulation result.

  18. 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.

  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. 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.

  1. Magnetic field tunable capacitive dielectric:ionic-liquid sandwich composites

    Science.gov (United States)

    Wu, Ye; Bhalla, Amar; Guo, Ruyan

    2016-03-01

    We examined the tunability of the capacitance for GaFeO3-ionic liquid-GaFeO3 composite material by external magnetic and electric field. Up to 1.6 folds of capacitance tunability could be achieved at 957 kHz with voltage 4 V and magnetic field 0.02 T applied. We show that the capacitance enhancement is due to the polarization coupling between dielectric layer and ionic liquid layer.

  2. 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.

  3. Calcium and Vitamin D

    Science.gov (United States)

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

  4. Circuit analysis and simulation of an ultrahigh-frequency capacitance sensor for scanning capacitance microscopy

    Science.gov (United States)

    Yang, Jing; Postula, A.; Bialkowski, M.

    2004-03-01

    Quantitative two-dimensional dopant profiling tools are urgently needed for nowadays semiconductor industry. Scanning Capacitance Microscopy (SCM) holds most promise to become such a tool. The key component of SCM is an ultra high frequency (UHF) capacitance sensor. The output of the sensor has been approximately regarded as dC/dV, the derivative of the capacitance between the SCM tip and the sample versus the applied bias voltage. The SCM dopant profiling involves extracting the dopant profile from the SCM signal using analytic or numerical simulation models of Metal-Oxide-Semiconductor physics. To achieve a quantitative SCM dopant profiling, the operational principle of the whole SCM measurement has to be well understood and correctly included in those models. Recently, experimental evidences show the SCM signal is dramatically affected by many SCM experimental factors, including the behavior of the UHF capacitance sensor. However, till now, very little research has been reported on the behavior of the sensor in SCM measurement of semiconductors. In this paper, we derive an analytic expression of the sensor output, a circuit simulation model of the sensor is established using Advanced Design System 2003, and the dependences of the sensor output on the SCM operational factors are simulated.

  5. Effect of calcium on anxiolytic activity of diazepam and verapamil in rats

    Directory of Open Access Journals (Sweden)

    Hiremath Sharanabasayyaswamy

    2010-01-01

    Full Text Available Objective: To analyze the role of calcium in anxiety and its effect on anxiolytic activity of diazepam and verapamil. Materials and Methods: Study was conducted using female albino rats in light and dark arena; a nonconflicting animal experimental model for anxiety. Animals were divided into six groups with six animals in each group. Test drugs, calcium gluconate (10 mg/kg, diazepam (1 mg/kg, verapamil (5 mg/kg, calcium + diazepam, and calcium + verapamil were administered intraperitoneally. Percentage of time spent in light arena and number of entries into light arena were the two parameters observed for 5 min after 30 min of drug administration. ANOVA test was used for statistical analysis. Results: Compared to the control group, diazepam group, and calcium group, only calcium + diazepam group showed considerable increase in mean percentage of time spent in light arena. However, this increase was statistically insignificant. In the case of total number of entries into light arena, animals in calcium + diazepam group showed statistically significant increase in total number of entries into light arena when compared to calcium group and diazepam group. Conclusion: Results of the study suggest that calcium may enhance the anxiolytic activity of diazepam, but has no effect on anxiolytic activity of verapamil.

  6. 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...

  7. 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.

  8. Interactions of Mitochondria/Metabolism and Calcium Regulation in Alzheimer's Disease: A Calcinist Point of View.

    Science.gov (United States)

    Gibson, Gary E; Thakkar, Ankita

    2017-02-08

    Decades of research suggest that alterations in calcium are central to the pathophysiology of Alzheimer's Disease (AD). Highly reproducible changes in calcium dynamics occur in cells from patients with both genetic and non-genetic forms of AD relative to controls. The most robust change is an exaggerated release of calcium from internal stores. Detailed analysis of these changes in animal and cell models of the AD-causing presenilin mutations reveal robust changes in ryanodine receptors, inositol tris-phosphate receptors, calcium leak channels and store activated calcium entry. Similar anomalies in calcium result when AD-like changes in mitochondrial enzymes or oxidative stress are induced experimentally. The calcium abnormalities can be directly linked to the altered tau phosphorylation, amyloid precursor protein processing and synaptic dysfunction that are defining features of AD. A better understanding of these changes is required before using calcium abnormalities as therapeutic targets.

  9. A capacitive biosensor based on an interdigitated electrode with nanoislands.

    Science.gov (United States)

    Jung, Ha-Wook; Chang, Young Wook; Lee, Ga-yeon; Cho, Sungbo; Kang, Min-Jung; Pyun, Jae-Chul

    2014-09-24

    A capacitive biosensor based on an interdigitated electrode (IDE) with nanoislands was developed for label-free detection of antigen-antibody interactions. To enable sensitive capacitive detection of protein adsorption, the nanoislands were fabricated between finger electrodes of the IDE. The effect of the nanoislands on the sensitive capacitive measurement was estimated using horseradish peroxidase (HRP) as a model protein. Additionally, a parylene-A film was coated on the IDE with nanoislands to improve the efficiency of protein immobilization. By using HRP and hepatitis B virus surface antigen (HBsAg) as model analytes, the effect of the parylene-A film on the capacitive detection of protein adsorption was demonstrated.

  10. Imaging calcium in neurons.

    Science.gov (United States)

    Grienberger, Christine; Konnerth, Arthur

    2012-03-08

    Calcium ions generate versatile intracellular signals that control key functions in all types of neurons. Imaging calcium in neurons is particularly important because calcium signals exert their highly specific functions in well-defined cellular subcompartments. In this Primer, we briefly review the general mechanisms of neuronal calcium signaling. We then introduce the calcium imaging devices, including confocal and two-photon microscopy as well as miniaturized devices that are used in freely moving animals. We provide an overview of the classical chemical fluorescent calcium indicators and of the protein-based genetically encoded calcium indicators. Using application examples, we introduce new developments in the field, such as calcium imaging in awake, behaving animals and the use of calcium imaging for mapping single spine sensory inputs in cortical neurons in vivo. We conclude by providing an outlook on the prospects of calcium imaging for the analysis of neuronal signaling and plasticity in various animal models.

  11. 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...

  12. 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.

  13. 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.

  14. Autonomous gliding entry guidance with

    Directory of Open Access Journals (Sweden)

    Guo Jie

    2015-10-01

    Full Text Available 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.

  15. 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.

  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. 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…

  18. 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...

  19. 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...

  20. 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 be ...

  1. 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...

  2. Distributed Capacitance of Coaxial Line With Perturbed Walls

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Perturbation method of boundary geometry(PMOBG) used in Laplacian problems is dealt with and the three-term perturbation expression of distributed capacitance of a coaxial line with perturbed walls is obtained. As an example,four-order expression of distributed capacitance of a elliptic coaxial line with small eccentricity is given.

  3. Nanoscale capacitance: A quantum tight-binding model

    Science.gov (United States)

    Zhai, Feng; Wu, Jian; Li, Yang; Lu, Jun-Qiang

    2017-01-01

    Landauer-Buttiker formalism with the assumption of semi-infinite electrodes as reservoirs has been the standard approach in modeling steady electron transport through nanoscale devices. However, modeling dynamic electron transport properties, especially nanoscale capacitance, is a challenging problem because of dynamic contributions from electrodes, which is neglectable in modeling macroscopic capacitance and mesoscopic conductance. We implement a self-consistent quantum tight-binding model to calculate capacitance of a nano-gap system consisting of an electrode capacitance C‧ and an effective capacitance Cd of the middle device. From the calculations on a nano-gap made of carbon nanotube with a buckyball therein, we show that when the electrode length increases, the electrode capacitance C‧ moves up while the effective capacitance Cd converges to a value which is much smaller than the electrode capacitance C‧. Our results reveal the importance of electrodes in modeling nanoscale ac circuits, and indicate that the concepts of semi-infinite electrodes and reservoirs well-accepted in the steady electron transport theory may be not applicable in modeling dynamic transport properties.

  4. 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

  5. Characterizing Inductive and Capacitive Nonlinear RLC Circuits : A Passivity Test

    NARCIS (Netherlands)

    García-Canseco, Eloísa; Jeltsema, Dimitri; Ortega, Romeo; Scherpen, Jacquelien M.A.

    2004-01-01

    Linear time-invariant RLC circuits are said to be inductive (capacitive) if the current waveform in sinusoidal steady-state has a negative (resp., positive) phase shift with respect to the voltage. Furthermore, it is known that the circuit is inductive (capacitive) if and only if the magnetic energy

  6. 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.

  7. Effect of estrogens on boar sperm capacitation in vitro

    Directory of Open Access Journals (Sweden)

    Ded Lukas

    2010-07-01

    Full Text Available Abstract Background Mammalian sperm must undergo a series of controlled molecular processes in the female reproductive tract called capacitation before they are capable of penetrating and fertilizing the egg. Capacitation, as a complex biological process, is influenced by many molecular factors, among which steroidal hormone estrogens play their role. Estrogens, present in a high concentration in the female reproductive tract are generally considered as primarily female hormones. However, there is increasing evidence of their important impact on male reproductive parameters. The purpose of this study is to investigate the effect of three natural estrogens such as estrone (E1, 17beta-estradiol (E2 and estriol (E3 as well as the synthetical one, 17alpha-ethynylestradiol (EE2 on boar sperm capacitation in vitro. Methods Boar sperm were capacitated in vitro in presence of estrogens. Capacitation progress in control and experimental samples was analyzed by flow cytometry with the anti-acrosin monoclonal antibody (ACR.2 at selected times of incubation. Sperm samples were analyzed at 120 min of capacitation by CTC (chlortetracycline assay, immunocytochemistry and flow cytometry with anti-acrosin ACR.2 antibody. Furthermore, sperm samples and capacitating media were analyzed by immunocytochemistry, ELISA with the ACR.2 antibody, and the acrosin activity assay after induced acrosomal reaction (AR. Results Estrogens stimulate sperm capacitation of boar sperm collected from different individuals. The stimulatory effect depends on capacitation time and is highly influenced by differences in the response to estrogens such as E2 by individual animals. Individual estrogens have relatively same effect on capacitation progress. In the boar samples with high estrogen responsiveness, estrogens stimulate the capacitation progress in a concentration-dependent manner. Furthermore, estrogens significantly increase the number of acrosome-reacted sperm after zona

  8. Capacitated dynamic lot sizing with capacity acquisition

    DEFF Research Database (Denmark)

    Li, Hongyan; Meissner, Joern

    2011-01-01

    batch, along with inventory carrying costs. The production per period is limited by a capacity restriction. The underlying capacity must be purchased up front for the upcoming season and remains constant over the entire season. We assume that the capacity acquisition cost is smooth and convex......One of the fundamental problems in operations management is determining the optimal investment in capacity. Capacity investment consumes resources and the decision, once made, is often irreversible. Moreover, the available capacity level affects the action space for production and inventory...... planning decisions directly. In this article, we address the joint capacitated lot-sizing and capacity-acquisition problems. The firm can produce goods in each of the finite periods into which the production season is partitioned. Fixed as well as variable production costs are incurred for each production...

  9. Capacitated Dynamic Lot Sizing with Capacity Acquisition

    DEFF Research Database (Denmark)

    Li, Hongyan; Meissner, Joern

    with inventory carrying costs. The production per period limited by a capacity restriction. The underlying capacity must be purchased up front for the upcoming season and remains constant over the entire season. We assume that the capacity acquisition cost is smooth and convex. For this situation, we develop......One of the fundamental problems in operations management is to determine the optimal investment in capacity. Capacity investment consumes resources and the decision is often irreversible. Moreover, the available capacity level affects the action space for production and inventory planning decisions...... directly. In this paper, we address the joint capacitated lot sizing and capacity acquisition problem. The firm can produce goods in each of the finite periods into which the production season is partitioned. Fixed as well as variable production costs are incurred for each production batch, along...

  10. 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.

  11. Creatinine Diffusion Modeling in Capacitive Sensors

    Science.gov (United States)

    Mohabbati-Kalejahi, Elham; Azimirad, Vahid; Bahrami, Manouchehr

    2016-12-01

    In this paper, creatinine diffusion in capacitive sensors is discussed. The factors influencing the response time of creatinine biosensors are mathematically formulated and then three novel approaches for decreasing the response time are presented. At first, a piezoelectric actuator is used to vibrate the microtube that contains the blood sample, in order to reduce the viscosity of blood, and thus to increase the coefficient of diffusion. Then, the blood sample is assumed to be pushed through a porous medium, and the relevant conditions are investigated. Finally, the effect of the dentate shape of dielectric on response time is studied. The algorithms and the mathematical models are presented and discussed, and the results of simulations are illustrated. The response times for the first, second and third method are 60, 0.036 and about 31 s, respectively. It is also found that pumping results in very fast responses.

  12. [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.

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Re-entry flight clearance

    NARCIS (Netherlands)

    Juliana, S.

    2006-01-01

    The objective of the research was to identify and evaluate promising mathematical techniques for re-entry flight clearance. To fulfil this objective, two mathematical methods were investigated and developed: μ analysis for linear models and interval analysis for both linear and non-linear model

  19. 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

  20. 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…

  1. Nonequilibrium calcium dynamics regulate the autonomous firing pattern of rat striatal cholinergic interneurons.

    Science.gov (United States)

    Goldberg, Joshua A; Teagarden, Mark A; Foehring, Robert C; Wilson, Charles J

    2009-07-01

    Striatal cholinergic interneurons discharge rhythmically in two patterns associated with different afterhyperpolarization timescales, each dictated by a different calcium-dependent potassium current. Single spiking depends on a medium-duration afterhyperpolarization (mAHP) generated by rapid SK currents that are associated with N-type calcium channels. Periodic bursting is driven by a delayed and slowly decaying afterhyperpolarization (sAHP) current associated with L-type channels. Using calcium imaging we show that the calcium transients underlying these currents exhibit two corresponding timescales throughout the somatodendritic tree. This result is not consistent with spatial compartmentalization of calcium entering through the two calcium channels and acting on the two potassium currents, or with differences in channel gating kinetics of the calcium dependent potassium currents. Instead, we show that nonequilibrium dynamics of calcium redistribution among cytoplasmic binding sites with different calcium binding kinetics can give rise to multiple timescales within the same cytoplasmic volume. The resulting independence of mAHP and sAHP currents allows cytoplasmic calcium to control two different and incompatible firing patterns (single spiking or bursting and pausing), depending on whether calcium influx is pulsatile or sustained. During irregular firing, calcium entry at both timescales can be detected, suggesting that an interaction between the medium and slow calcium-dependent afterhyperpolarizations may underlie this firing pattern.

  2. 19 CFR 142.3a - Entry numbers.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Entry numbers. 142.3a Section 142.3a Customs... (CONTINUED) ENTRY PROCESS Entry Documentation § 142.3a Entry numbers. (a) Placement on CBP forms. The importer or broker shall place an 11 character entry number on the entry and corresponding entry...

  3. 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.

  4. 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.

  5. Calcium - Function and effects

    NARCIS (Netherlands)

    Liang, Jianfen; He, Yifan; Gao, Qian; Wang, Xuan; Nout, M.J.R.

    2016-01-01

    Rice is the primary food source for more than half of the world population. Levels of calcium contents and inhibitor - phytic acid are summarized in this chapter. Phytic acid has a very strong chelating ability and it is the main inhibit factor for calcium in rice products. Calcium contents in br

  6. 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...

  7. 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.

  8. 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.

  9. 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...

  10. 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.

  11. 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.

  12. 19 CFR 143.36 - Form of immediate delivery, entry and entry summary.

    Science.gov (United States)

    2010-04-01

    ... Form of immediate delivery, entry and entry summary. (a) Electronic form of data. If Customs determines... 19 Customs Duties 2 2010-04-01 2010-04-01 false Form of immediate delivery, entry and entry summary. 143.36 Section 143.36 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF...

  13. 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.

  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. 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.

  16. 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 ...

  17. 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.

  18. Zinc modulation of calcium activity at the photoreceptor terminal: a calcium imaging study.

    Science.gov (United States)

    Anastassov, Ivan; Shen, Wen; Ripps, Harris; Chappell, Richard L

    2013-07-01

    There is abundant experimental evidence that zinc ions (Zn(2+)) are present in the synaptic vesicles of vertebrate photoreceptors, and that they are co-released with glutamate. Here we show that increasing the concentration of extracellular zinc (2 μM-2 mM) suppresses the entry of calcium into the synaptic terminals of isolated salamander double cones. The resultant dose-dependent curve was fit by an inverse Hill equation having an IC50 of 38 μM, and Hill coefficient of 1.1. Because there is currently no reliable way to measure the concentration of extracellular zinc, it is not known whether the zinc released under normal circumstances is of physiological significance. In an attempt to circumvent this problem we used zinc chelators to reduce the available pool of endogenous zinc. This enabled us to determine how the absence of zinc affected calcium entry. We found that when intra- or extra-cellular zinc was chelated by 250 μM of membrane-permeable TPEN or 500 μM of membrane-impermeable histidine, there was a significant rise in the depolarization-induced intracellular calcium level within photoreceptor terminals. This increase in internal [Ca(2+)] will undoubtedly lead to a concomitant increase in glutamate release. In addition, we found that blocking the L-type calcium channels that are expressed on the synaptic terminals of photoreceptors with 50 μM nicardipine or 100 μM verapamil abolished the effects of zinc chelation. These findings are a good indication that, when released in vivo, the zinc concentration is sufficient to suppress voltage-gated calcium channels, and reduce the rate of glutamate release from photoreceptor terminals.

  19. 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

  20. Quantum Capacitance of a Topological Insulator-Ferromagnet Interface.

    Science.gov (United States)

    Siu, Zhuo Bin; Chowdhury, Debashree; Jalil, Mansoor B A; Basu, Banasri

    2017-03-24

    We study the quantum capacitance in a topological insulator thin film system magnetized in the in-plane direction in the presence of an out-of-plane magnetic field and hexagonal warping. To first order, the modification in quantum capacitance due to hexagonal warping compared to the clean case, where both the in-plane magnetization and hexagonal warping are absent, is always negative, and increases in magnitude monotonically with the energy difference from the charge neutrality point. In contrast, the change in the quantum capacitance due to in-plane magnetization oscillates with the energy in general, except when a certain relation between the inter-surface coupling, out of plane Zeeman energy splitting and magnetic field strength is satisfied. In this special case, the quantum capacitance remains unchanged by the in-plane magnetization for all energies.

  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. 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...

  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. 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.

  5. 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)

  6. 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.

  7. 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.

  8. 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.

  9. Capacitance Variation of Electrolyte-Gated Bilayer Graphene Based Transistors

    OpenAIRE

    Hediyeh Karimi; Rubiyah Yusof; Mohammad Taghi Ahmadi; Mehdi Saeidmanesh; Meisam Rahmani; Elnaz Akbari; Wong King Kiat

    2013-01-01

    Quantum capacitance of electrolyte-gated bilayer graphene field-effect transistors is investigated in this paper. Bilayer graphene has received huge attention due to the fact that an energy gap could be opened by chemical doping or by applying external perpendicular electric field. So, this extraordinary property can be exploited to use bilayer graphene as a channel in electrolyte-gated field-effect transistors. The quantum capacitance of bi-layer graphene with an equivalent circuit is presen...

  10. Modeling high-frequency capacitance in SOI MOS capacitors

    Science.gov (United States)

    Łukasiak, Lidia; Jasiński, Jakub; Beck, Romuald B.; Ikraiam, Fawzi A.

    2016-12-01

    This paper presents a model of high frequency capacitance of a SOI MOSCAP. The capacitance in strong inversion is described with minority carrier redistribution in the inversion layer taken into account. The efficiency of the computational process is significantly improved. Moreover, it is suitable for the simulation of thin-film SOI structures. It may also be applied to the characterization of non-standard SOI MOSCAPS e.g. with nanocrystalline body.

  11. 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/%.

  12. Simulation Study on Quantum Capacitances of Graphene Nanoribbon VLSI Interconnects

    Science.gov (United States)

    Dutta, Arin; Rahman, Silvia; Nandy, Turja; Mahmood, Zahid Hasan

    2016-03-01

    In this paper, study on the capacitive effects of Graphene nanoribbon (GNR) in VLSI interconnect has been studied as a function of GNR width, Fermi function and gate voltage. The quantum capacitance of GNR has been simulated in terms of Fermi function for three different values of insulator thickness — 1.5nm, 2nm and 2.5nm. After that, quantum capacitance is studied in both degenerate and nondegenerate region with respect to Fermi function and gate voltage of range 1-5V. Then, the total capacitance of GNR is studied as a function of gate voltage of -2-5V range at degenerate and nondegenerate regions, where width of GNR is considered 4nm. Finally, the total capacitance of GNR is studied in both regions with varying GNR width, considering fixed gate voltage of 3V. After analyzing these simulations, it has been found that GNR in degenerate region shows nearly steady capacitance under a certain applied gate voltage.

  13. Atmospheric Entry Experiments at IRS

    Science.gov (United States)

    Auweter-Kurtz, M.; Endlich, P.; Herdrich, G.; Kurtz, H.; Laux, T.; Löhle, S.; Nazina, N.; Pidan, S.

    2002-01-01

    Entering the atmosphere of celestial bodies, spacecrafts encounter gases at velocities of several km/s, thereby being subjected to great heat loads. The thermal protection systems and the environment (plasma) have to be investigated by means of computational and ground facility based simulations. For more than a decade, plasma wind tunnels at IRS have been used for the investigation of TPS materials. Nevertheless, ground tests and computer simulations cannot re- place space flights completely. Particularly, entry mission phases encounter challenging problems, such as hypersonic aerothermodynamics. Concerning the TPS, radiation-cooled materials used for reuseable spacecrafts and ablator tech- nologies are of importance. Besides the mentioned technologies, there is the goal to manage guidance navigation, con- trol, landing technology and inflatable technologies such as ballutes that aim to keep vehicles in the atmosphere without landing. The requirement to save mass and energy for planned interplanetary missions such as Mars Society Balloon Mission, Mars Sample Return Mission, Mars Express or Venus Sample Return mission led to the need for manoeuvres like aerocapture, aero-breaking and hyperbolic entries. All three are characterized by very high kinetic vehicle energies to be dissipated by the manoeuvre. In this field flight data are rare. The importance of these manoeuvres and the need to increase the knowledge of required TPS designs and behavior during such mission phases point out the need of flight experiments. As result of the experience within the plasma diagnostic tool development and the plasma wind tunnel data base, flight experiments like the PYrometric RE-entry EXperiment PYREX were developed, fully qualified and successfully flown. Flight experiments such as the entry spectrometer RESPECT and PYREX on HOPE-X are in the conceptual phase. To increase knowledge in the scope of atmospheric manoeuvres and entries, data bases have to be created combining both

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

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yi-hua [Department of Clinical Laboratory, The Second Affiliated Hospital of Harbin Medical University, Harbin 150086 (China); Li, Yong-quan [Harbin Medical University, Harbin 150086 (China); Feng, Shan-li [Department of Clinical Laboratory, The Second Affiliated Hospital of Harbin Medical University, Harbin 150086 (China); Li, Bao-xin; Pan, Zhen-wei [Department of Pharmacology, Harbin Medical University, Harbin 150086 (China); Xu, Chang-qing [Department of Pathophysiology, Harbin Medical University, Harbin 150086 (China); Li, Ting-ting [Department of Clinical Laboratory, The Second Affiliated Hospital of Harbin Medical University, Harbin 150086 (China); Yang, Bao-feng, E-mail: syh200415@yahoo.com.cn [Department of Pharmacology, Harbin Medical University, Harbin 150086 (China)

    2010-04-16

    Capacitative calcium entry (CCE) refers to the influx of calcium through plasma membrane channels activated on depletion of endoplasmic sarcoplasmic/reticulum (ER/SR) Ca{sup 2+} 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 Ca{sup 2+} imaging, we found that the depletion of ER/SR Ca{sup 2+} stores by thapsigargin (TG) elicited a transient rise in cytoplasmic Ca{sup 2+} ([Ca{sup 2+}]{sub i}), followed by sustained increase depending on extracellular Ca{sup 2+}. But, TRP channels inhibitor (SKF96365), not L-type channels or the Na{sup +}/Ca{sup 2+} exchanger inhibitors, inhibited [Ca{sup 2+}]{sub i} relatively high. Then, we found that the stimulation of CaR with its activator gadolinium chloride (GdCl{sub 3}) or by an increased extracellular Ca{sup 2+}([Ca{sup 2+}]{sub o}) increased the concentration of intracelluar Ca{sup 2+}, whereas, the sustained elevation of [Ca{sup 2+}]{sub i} was reduced in the presence of SKF96365. Similarly, the duration of [Ca{sup 2+}]{sub i} increase was also shortened in the absence of extracellular Ca{sup 2+}. Western blot analysis showed that GdCl{sub 3} increased the expression of TRPC6, which was reversed by SKF96365. Additionally, SKF96365 reduced cardiomyocyte apoptosis induced by GdCl{sub 3}. Our results suggested that CCE exhibited in rat neonatal myocytes and CaR activation induced Ca{sup 2+}-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.

  15. Calcium is important forus.

    Institute of Scientific and Technical Information of China (English)

    高利平

    2005-01-01

    Calcium is important for our health.We must have it in our diet to stay well.A good place to get it is from dairy products like milk, cheese and ice cream.One pound of cheese has fifty times the calcium we should have every day.Other foods have less.For example,a pound of beans also has calcium.But it has only three times the amount we ought to have daily.

  16. 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.

  17. Pertussis toxin nullifies the depolarisation of the membrane potential and the stimulation of the rapid phase of 45Ca2+ entry through L-type calcium channels that are produced by follicle stimulating hormone in 10- to 12-day-old-rat Sertoli cells.

    Directory of Open Access Journals (Sweden)

    Ana P Jacobus

    2010-10-01

    Full Text Available The aim of this study was to evaluate the effect of pertussis toxin (PTX on the depolarising component of the action of FSH on the membrane potential of Sertoli cells, which is linked to the rapid entry of Ca2+ into cells and to the Ca2+-dependent transport of neutral amino acids by the A system. This model allowed us to analyse the involvement of Gi proteins in the action of FSH in these phenomena. In parallel, using an inactive analogue of IGF-1, JB1, and an anti-IGF-I antibody we investigated the possible mediating role of IGF-I on these effects of FSH because IGF-I is produced and released by testicular cells in response to stimulation by FSH and shows depolarisation effects on membrane potential similar to those from FSH. Our results have the following implications: a the rapid membrane actions of FSH, which occur in a time-frame of seconds to min and include the depolarisation of the membrane potential, and stimulation of 45Ca2+ uptake and [14C]- methyl aminoisobutyric acid ([14C]-MeAIB transport, are nullified by the action of PTX and, therefore, are probably mediated by GiPCR activation; b the effects of FSH were also nullified by verapamil, an L-type voltage-dependent Ca2+ channel blocker; c wortmannin, an inhibitor of PI3K, prevented FSH stimulation of 45Ca2+ entry and [14C]-MeAIB transport; and d these FSH actions are independent of the IGF-I effects. In conclusion, these results strongly suggest that the rapid action of FSH on L-type Ca2+ channel activity in Sertoli cells from 10- to 12-day-old rats is mediated by the Gi/βγ/PI3Kγ pathway, independent of the effects of IGF-I.

  18. 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.

  19. Calcium channel blockers in cardiovascular pharmacotherapy.

    Science.gov (United States)

    Godfraind, Theophile

    2014-11-01

    This paper summarizes the pharmacological properties of calcium channel blockers (CCBs), their established therapeutic uses for cardiovascular disorders and the current improvement of their clinical effects through drug combinations. Their identification resulted from study of small molecules including coronary dilators, which were named calcium antagonists. Further experiments showed that they reduced contraction of arteries by inhibiting calcium entry and by interacting with binding sites identified on voltage-dependent calcium channels. This led to the denomination calcium channel blockers. In short-term studies, by decreasing total peripheral resistance, CCBs lower arterial pressure. By unloading the heart and increasing coronary blood flow, CCBs improve myocardial oxygenation. In long-term treatment, the decrease in blood pressure is more pronounced in hypertensive than in normotensive patients. A controversy on the safety of CCBs ended after a large antihypertensive trial (ALLHAT) sponsored by the National Heart, Lung, and Blood Institute. There are two main types of CCBs: dihydopyridine and non-dihydropyridine; the first type is vascular selective. Dihydropyrines are indicated for hypertension, chronic, stable and vasospastic angina. Non-dihydropyridines have the same indications plus antiarrythmic effects in atrial fibrillation or flutter and paroxysmal supraventricular tachycardia. In addition, CCBs reduced newly formed coronary lesions in atherosclerosis. In order to reach recommended blood pressure goals, there is a recent therapeutic move by combination of CCBs with other antihypertensive agents particularly with inhibitors acting at the level of the renin-angiotensin system. They are also combined with statins. Prevention of dementia has been reported in hypertensive patients treated with nitrendipine, opening a way for further studies on CCBs' beneficial effect in cognitive deterioration associated with aging.

  20. 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

  1. 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 inhibi...

  2. 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.

  3. Capacitance and compressibility of heterostructures with strong electronic correlations

    Science.gov (United States)

    Steffen, Kevin; Frésard, Raymond; Kopp, Thilo

    2017-01-01

    Strong electronic correlations related to a repulsive local interaction suppress the electronic compressibility in a single-band model, and the capacitance of a corresponding metallic film is directly related to its electronic compressibility. Both statements may be altered significantly when two extensions to the system are implemented which we investigate here: (i) we introduce an attractive nearest-neighbor interaction V as antagonist to the repulsive onsite repulsion U , and (ii) we consider nanostructured multilayers (heterostructures) assembled from two-dimensional layers of these systems. We determine the respective total compressibility κ and capacitance C of the heterostructures within a strong coupling evaluation, which builds on a Kotliar-Ruckenstein slave-boson technique. Whereas the capacitance C (n ) for electronic densities n close to half-filling is suppressed, illustrated by a correlation induced dip in C (n ) , it may be appreciably enhanced close to a van Hove singularity. Moreover, we show that the capacitance may be a nonmonotonic function of U close to half-filling for both attractive and repulsive V . The compressibility κ can differ from C substantially, as κ is very sensitive to internal electrostatic energies which in turn depend on the specific setup of the heterostructure. In particular, we show that a capacitor with a polar dielectric has a smaller electronic compressibility and is more stable against phase separation than a standard nonpolar capacitor with the same capacitance.

  4. 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.)

  5. Calcium signaling in neurodegeneration

    Directory of Open Access Journals (Sweden)

    Dreses-Werringloer Ute

    2009-05-01

    Full Text Available Abstract Calcium is a key signaling ion involved in many different intracellular and extracellular processes ranging from synaptic activity to cell-cell communication and adhesion. The exact definition at the molecular level of the versatility of this ion has made overwhelming progress in the past several years and has been extensively reviewed. In the brain, calcium is fundamental in the control of synaptic activity and memory formation, a process that leads to the activation of specific calcium-dependent signal transduction pathways and implicates key protein effectors, such as CaMKs, MAPK/ERKs, and CREB. Properly controlled homeostasis of calcium signaling not only supports normal brain physiology but also maintains neuronal integrity and long-term cell survival. Emerging knowledge indicates that calcium homeostasis is not only critical for cell physiology and health, but also, when deregulated, can lead to neurodegeneration via complex and diverse mechanisms involved in selective neuronal impairments and death. The identification of several modulators of calcium homeostasis, such as presenilins and CALHM1, as potential factors involved in the pathogenesis of Alzheimer's disease, provides strong support for a role of calcium in neurodegeneration. These observations represent an important step towards understanding the molecular mechanisms of calcium signaling disturbances observed in different brain diseases such as Alzheimer's, Parkinson's, and Huntington's diseases.

  6. Estimation of Transformer Winding Capacitances through Frequency Response Analysis - An Experimental Investigation

    Science.gov (United States)

    Shah, Krupa; Ragavan, K.

    2013-10-01

    This article focuses on developing a non-invasive method for determining capacitances using frequency response data. The proposed methodology involves acquiring driving-point impedance of the winding under consideration over wide frequency range. With certain terminal conditions and using the terminal impedance measured at specific frequencies, input and shunt capacitances are determined. For the purpose of estimating series capacitance of the winding, an algorithm is proposed. To demonstrate the capability of the method, initially model coils that have provisions for connecting external capacitances are considered. Then, it is found that the estimated values of capacitances are nearly same as those of connected capacitances. The method is, then, extended to transformer winding, and a capacitive ladder network is constructed. To assess the accuracy of estimation, capacitive voltage distribution is utilized. That is, the voltage distribution in the winding is compared with that of synthesized circuit. A good agreement between those data reveals that the estimated capacitance values are accurate.

  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. 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.

  9. Entry Into a Care Trajectory

    Directory of Open Access Journals (Sweden)

    Normand Carpentier

    2013-06-01

    Full Text Available A broad range of services are developing in response to the needs of an aging population. Although most interventions are carried out in the patient’s living environment—at the heart of society—few studies on service utilization refer to social theory. This paper suggests that studies on older people with chronic health conditions would benefit from a stronger theoretical foundation. Drawing on 15 in-depth interviews, it highlights the relevance of individualization processes and the network society, 2 central theoretical concerns in sociology. The research provides a unique perspective on the entry into the care trajectory and expands our comprehension of the emergence of a social organization that can respond to the needs of elderly patients. Data of this nature may be useful in service planning and the development of a care-centered approach.

  10. 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.

  11. 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)

  12. 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.

  13. CMOS capacitive biosensors for highly sensitive biosensing applications.

    Science.gov (United States)

    Chang, An-Yu; Lu, Michael S-C

    2013-01-01

    Magnetic microbeads are widely used in biotechnology and biomedical research for manipulation and detection of cells and biomolecules. Most lab-on-chip systems capable of performing manipulation and detection require external instruments to perform one of the functions, leading to increased size and cost. This work aims at developing an integrated platform to perform these two functions by implementing electromagnetic microcoils and capacitive biosensors on a CMOS (complementary metal oxide semiconductor) chip. Compared to most magnetic-type sensors, our detection method requires no externally applied magnetic fields and the associated fabrication is less complicated. In our experiment, microbeads coated with streptavidin were driven to the sensors located in the center of microcoils with functionalized anti-streptavidin antibody. Detection of a single microbead was successfully demonstrated using a capacitance-to-frequency readout. The average capacitance changes for the experimental and control groups were -5.3 fF and -0.2 fF, respectively.

  14. Extracting Impurity Locations using Scanning Capacitance Microscopy Measurements

    Directory of Open Access Journals (Sweden)

    AGHAEI, S.

    2016-08-01

    Full Text Available In this article we investigate the possibility to use scanning capacitance microscopy (SCM for the 2-D and 3-D "atomistic" dopant profiling of semiconductor materials. For this purpose, we first analyze the effects of random dopant fluctuations (RDF on SCM measurements with nanoscale probes and show that the discrete and random locations of dopant impurities significantly affect the differential capacitance measured in SCM experiments if the dimension of the probe is below 50 nm. Then, we present an algorithm to compute the x, y, and z coordinates of the ionized impurities in the semiconductor material using a set of SCM measurements. The algorithm is based on evaluating the doping sensitivity functions of the differential capacitance and uses a gradient-based iterative method to compute the locations of dopants. Finally, we discuss a standard simulation case and show that we are able to successfully retrieve the locations of the ionized impurities using the proposed algorithm.

  15. A Wearable Capacitive Sensor for Monitoring Human Respiratory Rate

    Science.gov (United States)

    Kundu, Subrata Kumar; Kumagai, Shinya; Sasaki, Minoru

    2013-04-01

    Realizing an untethered, low-cost, and comfortably wearable respiratory rate sensor for long-term breathing monitoring application still remains a challenge. In this paper, a conductive-textile-based wearable respiratory rate sensing technique based on the capacitive sensing approach is proposed. The sensing unit consists of two conductive textile electrodes that can be easily fabricated, laminated, and integrated in garments. Respiration cycle is detected by measuring the capacitance of two electrodes placed on the inner anterior and posterior sides of a T-shirt at either the abdomen or chest position. A convenient wearable respiratory sensor setup with a capacitance-to-voltage converter has been devised. Respiratory rate as well as breathing mode can be accurately identified using the designed sensor. The sensor output provides significant information on respiratory flow. The effectiveness of the proposed system for different breathing patterns has been evaluated by experiments.

  16. 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.

  17. 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...

  18. Extraction method for parasitic capacitances and inductances of HEMT models

    Science.gov (United States)

    Zhang, HengShuang; Ma, PeiJun; Lu, Yang; Zhao, BoChao; Zheng, JiaXin; Ma, XiaoHua; Hao, Yue

    2017-03-01

    A new method to extract parasitic capacitances and inductances for high electron-mobility transistors (HEMTs) is proposed in this paper. Compared with the conventional extraction method, the depletion layer is modeled as a physically significant capacitance model and the extrinsic values obtained are much closer to the actual results. In order to simulate the high frequency behaviour with higher precision, series parasitic inductances are introduced into the cold pinch-off model which is used to extract capacitances at low frequency and the reactive elements can be determined simultaneously over the measured frequency range. The values obtained by this method can be used to establish a 16-elements small-signal equivalent circuit model under different bias conditions. The results show good agreements between the simulated and measured scattering parameters up to 30 GHz.

  19. 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.

  20. 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.

  1. 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...

  2. Evidence for a possible calcium flux dependent cardiomyopathy in hyperthyroidism

    Energy Technology Data Exchange (ETDEWEB)

    Barat, J.L.; Wicker, P.; Manley, W.; Brendel, A.J.; Lefort, G.; San Galli, F.; Commenges-Ducos, M.; Latapie, J.L.; Riviere, J.; Ducassou, D.

    1985-05-01

    This study was designed to test the hypothesis that the impaired functional cardiac reserve to exercise in hyperthyroidism is related to alterations in the regulation of calcium transport. In 2l hyperthyroid patients, the left ventricular ejection fraction (LVEF) was measured using equilibrium gated radionuclide angiocardiography at rest and during supine dynamic exercise. After a recovery period, the patients performed a second exercise study after random administration of Verapamil, a calcium entry blocker (11 pts), or propanolol, a beta adrenergic antagonist (10 pts) for comparison. The results showed i) normal resting LVEF with no significant change during exercise before any medication, ii) resting LVEF significantly decreased after Propanolol, and no significantly changed after Verapamil, iii) during exercise, significant increase of LVEF after Verapamil, and no significant change after Propanolol. These results are consistent with previous studies showing that abnormal change in LVEF during exercise in hyperthyroidism seems independent of beta adrenergic activation, and suggest a reversible functional cardiomyopathy dependent of calcium transporting systems.

  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. SEMICONDUCTOR DEVICES Multi-bias capacitance voltage characteristic of AlGaN/GaN HEMT

    Science.gov (United States)

    Yan, Pu; Liang, Wang; Tingting, Yuan; Sihua, Ouyang; Lei, Pang; Guoguo, Liu; Weijun, Luo; Xinyu, Liu

    2010-10-01

    The method of multi-bias capacitance voltage measurement is presented. The physical meaning of gate—source and gate—drain capacitances in AlGaN/GaN HEMT and the variations in them with different bias conditions are discussed. A capacitance model is proposed to reflect the behaviors of the gate—source and gate—drain capacitances, which shows a good agreement with the measured capacitances, and the power performance obtains good results compared with the measured data from the capacitance model.

  5. Differential CaMKII regulation by voltage-gated calcium channels in the striatum.

    Science.gov (United States)

    Pasek, Johanna G; Wang, Xiaohan; Colbran, Roger J

    2015-09-01

    Calcium signaling regulates synaptic plasticity and many other functions in striatal medium spiny neurons to modulate basal ganglia function. Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is a major calcium-dependent signaling protein that couples calcium entry to diverse cellular changes. CaMKII activation results in autophosphorylation at Thr286 and sustained calcium-independent CaMKII activity after calcium signals dissipate. However, little is known about the mechanisms regulating striatal CaMKII. To address this, mouse brain slices were treated with pharmacological modulators of calcium channels and punches of dorsal striatum were immunoblotted for CaMKII Thr286 autophosphorylation as an index of CaMKII activation. KCl depolarization increased levels of CaMKII autophosphorylation ~2-fold; this increase was blocked by an LTCC antagonist and was mimicked by treatment with pharmacological LTCC activators. The chelation of extracellular calcium robustly decreased basal CaMKII autophosphorylation within 5min and increased levels of total CaMKII in cytosolic fractions, in addition to decreasing the phosphorylation of CaMKII sites in the GluN2B subunit of NMDA receptors and the GluA1 subunit of AMPA receptors. We also found that the maintenance of basal levels of CaMKII autophosphorylation requires low-voltage gated T-type calcium channels, but not LTCCs or R-type calcium channels. Our findings indicate that CaMKII activity is dynamically regulated by multiple calcium channels in the striatum thus coupling calcium entry to key downstream substrates.

  6. 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

  7. Touch mode micromachined capacitive pressure sensor with signal conditioning electronics

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio; Eriksen, Gert F.; Christensen, Carsten

    2010-01-01

    is one of the key challenges nowadays. In this context, house heating is a priority for environmental issues. For this reason, the possibilities of using a low power consumption technique, such as capacitive pressure sensing, in harsh environments is a concrete market opportunity. Our aim is therefore....... A measurement setup was arranged and tested for accuracy and reliability with respect to hysteresis. Finally, designs with different radii of the top plate were characterized by a capacitance versus pressure curve at different frequencies and temperatures (Fig. 3). Industrial possibilities Energy saving systems...

  8. 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.

  9. 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.

  10. 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.

  11. Comprehensive measurements of GaAs pixel detectors capacitance

    CERN Document Server

    Caria, M; D'Auria, S; Lai, A; Randaccio, P; Cadeddu, S

    2002-01-01

    We have studied GaAs pixel detectors on semi-insulating wafers with Schottky contacts. We performed comprehensive measurements on the inter-pixel and capacitance to back plane. Being semi-insulating, the behaviour is totally different with respect to other common semiconductors, such as high resistivity silicon. Non-homogeneities are also an issue, due to both the contacts and the crystal bulk. In order to detect them and their influence on capacitance, we undertook systematic measurements with different configurations of the measuring electrodes.

  12. 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.

  13. Micromachined capacitive pressure sensor with signal conditioning electronics

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio

    Micromachined capacitive pressure sensors for harsh environment together with interfacing electronic circuits have been studied in this project. Micro-electromechanical systems (MEMS) have been proposed as substitutes for macro scale sensor’s systems in many different fields and are the only...... a great deal of sensors are used. Pressure sensors are among the most successful MEMS and are used in a huge variety of applications. In this project an absolute capacitive pressure sensor has been developed with the aim to integrate it in pump control systems to improve the efficiency of the pump...

  14. 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%.

  15. Quantum capacitance in monolayers of silicene and related buckled materials

    Science.gov (United States)

    Nawaz, S.; Tahir, M.

    2016-02-01

    Silicene and related buckled materials are distinct from both the conventional two dimensional electron gas and the famous graphene due to strong spin orbit coupling and the buckled structure. These materials have potential to overcome limitations encountered for graphene, in particular the zero band gap and weak spin orbit coupling. We present a theoretical realization of quantum capacitance which has advantages over the scattering problems of traditional transport measurements. We derive and discuss quantum capacitance as a function of the Fermi energy and temperature taking into account electron-hole puddles through a Gaussian broadening distribution. Our predicted results are very exciting and pave the way for future spintronic and valleytronic devices.

  16. [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.

  17. 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 fin......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...

  18. 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 technological...

  19. 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....

  20. 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...

  1. 19 CFR 142.3 - Entry documentation required.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Entry documentation required. 142.3 Section 142.3... TREASURY (CONTINUED) ENTRY PROCESS Entry Documentation § 142.3 Entry documentation required. (a) Contents. Except as provided in paragraph (b) of this section, the entry documentation required to secure...

  2. 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.

  3. Adaptive Text Entry for Mobile Devices

    DEFF Research Database (Denmark)

    Proschowsky, Morten Smidt

    The reduced size of many mobile devices makes it difficult to enter text with them. The text entry methods are often slow or complicated to use. This affects the performance and user experience of all applications and services on the device. This work introduces new easy-to-use text entry methods...... 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...... be touch sensitive wheels, sliders or similar input devices. The interaction design of TUP is done with a combination of high level task models and low level models of human motor behaviour. Three prototypes of TUP are designed and evaluated by more than 30 users. Observations from the evaluations are used...

  4. Calcium and Your Child

    Science.gov (United States)

    ... for dinner. Create mini-pizzas by topping whole-wheat English muffins or bagels with pizza sauce, low- ... Minerals Do I Need to Drink Milk? Lactose Intolerance Becoming a Vegetarian Soy Foods and Health Calcium ...

  5. Stoichiometry of Calcium Medicines

    Science.gov (United States)

    Pinto, Gabriel

    2005-01-01

    The topic of calcium supplement and its effects on human lives is presented in the way of questions to the students. It enables the students to realize the relevance of chemistry outside the classroom surrounding.

  6. 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.

  7. 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.

  8. 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

  9. Stray capacitances in the watt balance operation: electrostatic forces

    CERN Document Server

    Quagliotti, Danilo

    2014-01-01

    In a watt balance, stray capacitances exist between the coil and the magnet. Since the electric current flowing in the coil originates a difference between the coil and magnet electric-potentials, their electrostatic interactions must be taken into account. This paper reports the results of a finite element analysis of the forces acting on the coil.

  10. 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.  

  11. A Multifunction Low-Power Preamplifier for MEMS Capacitive Microphones

    DEFF Research Database (Denmark)

    Jawed, Syed Arsalan; Nielsen, Jannik Hammel; Gottardi, Massimo;

    2009-01-01

    A multi-function two-stage chopper-stabilized preamplifier (PAMP) for MEMS capacitive microphones (MCM) is presented. The PAMP integrates digitally controllable gain, high-pass filtering and offset control, adding flexibility to the front-end readout of MCMs. The first stage of the PAMP consists...

  12. 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...

  13. 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

  14. Waterproof, Ultrahigh Areal-Capacitance, Wearable Supercapacitor Fabrics.

    Science.gov (United States)

    Yang, Yu; Huang, Qiyao; Niu, Liyong; Wang, Dongrui; Yan, Casey; She, Yiyi; Zheng, Zijian

    2017-02-24

    High-performance supercapacitors (SCs) are promising energy storage devices to meet the pressing demand for future wearable applications. Because the surface area of a human body is limited to 2 m(2) , the key challenge in this field is how to realize a high areal capacitance for SCs, while achieving rapid charging, good capacitive retention, flexibility, and waterproofing. To address this challenge, low-cost materials are used including multiwall carbon nanotube (MWCNT), reduced graphene oxide (RGO), and metallic textiles to fabricate composite fabric electrodes, in which MWCNT and RGO are alternatively vacuum-filtrated directly onto Ni-coated cotton fabrics. The composite fabric electrodes display typical electrical double layer capacitor behavior, and reach an ultrahigh areal capacitance up to 6.2 F cm(-2) at a high areal current density of 20 mA cm(-2) . All-solid-state fabric-type SC devices made with the composite fabric electrodes and water-repellent treatment can reach record-breaking performance of 2.7 F cm(-2) at 20 mA cm(-2) at the first charge-discharge cycle, 3.2 F cm(-2) after 10 000 charge-discharge cycles, zero capacitive decay after 10 000 bending tests, and 10 h continuous underwater operation. The SC devices are easy to assemble into tandem structures and integrate into garments by simple sewing.

  15. 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

  16. 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.

  17. 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.

  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. 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.

  20. 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

  1. Micro coriolis mass flow sensor with integrated capacitive readout

    NARCIS (Netherlands)

    Haneveld, J.; Lammerink, T.S.J.; Boer, de M.J.; Wiegerink, R.J.

    2009-01-01

    We have realized a micromachined micro Coriolis mass flow sensor with integrated capacitive readout to detect the extremely small Coriolis vibration of the sensor tube. A special comb-like detection electrode design eliminates the need for multiple metal layers and sacrificial layer etching methods.

  2. An organic integrated capacitive DC-DC up-converter

    NARCIS (Netherlands)

    Marien, H.; Steyaert, M.; Steudel, S.; Vicca, P.; Smout, S.; Gelinck, G.H.; Heremans, P.L.

    2010-01-01

    In this paper a fully integrated organic DC-DC upconverter is presented in a pentacene p-type only technology. This 3-stage Dickson converter reaches a voltage conversion factor of 3 for a purely capacitive load and 2.5 for a 10 μA load current. The maximal output voltage goes up to 75 V and the Dic

  3. 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

  4. Production of pulsed electric fields using capacitively coupled electrodes

    Science.gov (United States)

    Kendall, B. R. F.; Schwab, F. A. S.

    1980-01-01

    It is shown that pulsed electric fields can be produced over extended volumes by taking advantage of the internal capacitances in a stacked array of electrodes. The design, construction, and performance of practical arrays are discussed. The prototype arrays involved fields of 100-1000 V/cm extending over several centimeters. Scaling to larger physical dimensions is straightforward.

  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. 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

  8. Parasitic capacitance characteristics of deep submicrometre grooved gate MOSFETs

    Science.gov (United States)

    Sreelal, S.; Lau, C. K.; Samudra, G. S.

    2002-03-01

    Grooved gate metal-oxide-semiconductor field-effect transistors (MOSFETs) are known to alleviate many of the short channel and hot carrier effects that arise when MOSFET devices are scaled down to very short channel lengths. However, they exhibit much higher parasitic capacitance with stronger bias dependence when compared to conventional planar devices. In this paper, we present a model for gate-to-drain and gate-to-source capacitance characteristics of a deep submicrometre grooved gate MOSFET. Both the intrinsic and extrinsic parts of the capacitance are modelled separately. In particular, the model presents a novel but simple way to account for the accumulation layer formation in the source/drain region of MOSFETs due to the application of the gate voltage. The results are compared with those obtained from a two-dimensional device simulator. The close match between the modelled and simulated data establishes the validity of the model. The model is then used to account for the superiority of capacitance characteristics of planar device structures and to arrive at optimization guidelines for grooved gate devices to match these characteristics.

  9. 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.

  10. Calcium and Calcium-Base Alloys

    Science.gov (United States)

    1949-01-01

    should be satisfactory, because the electrolytic process for •(!>: A. H. Everts and G. D. Baglev’, " Physical «nrt m<„.+„4 i «_ of Calcium«, Electrochem...Rev. Metalurgie , 3j2, (1), 129 (1935). 10 ^sm^mssss^ma^^ extension between two known loads, is preferable to the value of 3,700,000 p.B.i. obtained

  11. LABORATORY VOICE DATA ENTRY SYSTEM.

    Energy Technology Data Exchange (ETDEWEB)

    PRAISSMAN,J.L.SUTHERLAND,J.C.

    2003-04-01

    We have assembled a system using a personal computer workstation equipped with standard office software, an audio system, speech recognition software and an inexpensive radio-based wireless microphone that permits laboratory workers to enter or modify data while performing other work. Speech recognition permits users to enter data while their hands are holding equipment or they are otherwise unable to operate a keyboard. The wireless microphone allows unencumbered movement around the laboratory without a ''tether'' that might interfere with equipment or experimental procedures. To evaluate the potential of voice data entry in a laboratory environment, we developed a prototype relational database that records the disposal of radionuclides and/or hazardous chemicals Current regulations in our laboratory require that each such item being discarded must be inventoried and documents must be prepared that summarize the contents of each container used for disposal. Using voice commands, the user enters items into the database as each is discarded. Subsequently, the program prepares the required documentation.

  12. Novel Approaches to Inhibit HIV Entry

    Directory of Open Access Journals (Sweden)

    Chukwuka A. Didigu

    2012-02-01

    Full Text Available Human Immunodeficiency Virus (HIV entry into target cells is a multi-step process involving binding of the viral glycoprotein, Env, to its receptor CD4 and a coreceptor—either CCR5 or CXCR4. Understanding the means by which HIV enters cells has led to the identification of genetic polymorphisms, such as the 32 base-pair deletion in the ccr5 gene (ccr5∆32 that confers resistance to infection in homozygous individuals, and has also resulted in the development of entry inhibitors—small molecule antagonists that block infection at the entry step. The recent demonstration of long-term control of HIV infection in a leukemic patient following a hematopoietic stem cell transplant using cells from a ccr5∆32 homozygous donor highlights the important role of the HIV entry in maintaining an established infection and has led to a number of attempts to treat HIV infection by genetically modifying the ccr5 gene. In this review, we describe the HIV entry process and provide an overview of the different classes of approved HIV entry inhibitors while highlighting novel genetic strategies aimed at blocking HIV infection at the level of entry.

  13. 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.

  14. 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...

  15. [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

  16. 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.

  17. Advances in spacecraft atmospheric entry guidance

    Science.gov (United States)

    Benito Manrique, Joel

    In order to advance entry guidance technology two different research areas have been explored with the objective of increasing the reachable landing area and the landing accuracy for future Mars missions. Currently only the northern hemisphere of Mars is available for landing due to its low elevation. Only low elevation landing sites have the necessary atmospheric density to allow landing using current Entry, Descent and Landing (EDL) technology. In order to reach most of the Ancient Highlands, the majority of the southern hemisphere, advanced EDL technology is needed in multiple fields, including entry guidance. The first research area is the definition and applications of reachable and controllable sets for entry. The definition of the reachable and controllable sets provides a framework for the study of the capabilities of an entry vehicle in a given planet. Reachable and controllable sets can be used to comprehensively characterize the envelope of trajectories that a vehicle can fly, the sites it can reach and the entry states that can be accommodated. The sets can also be used for the evaluation of trajectory planning algorithms and to assist in the selection of the entry or landing sites. In essence, the reachable and controllable sets offer a powerful vehicle and trajectory analysis and design framework that allows for better mission design choices. In order to illustrate the use of the sets, they are computed for a representative Mars mission using two different vehicle configurations. The sets characterize the impact of the vehicle configuration on the entry capability. Furthermore, the sets are used to find the best skip-entry trajectory for a return from the Moon mission, highlighting the utility of the sets in atmospheric maneuvers other than entry. The second research area is the development of the components of an entry guidance algorithm that allow high elevation landing and provide as well high landing accuracy. The approach taken follows the

  18. Texting while driving: is speech-based text entry less risky than handheld text entry?

    Science.gov (United States)

    He, J; Chaparro, A; Nguyen, B; Burge, R J; Crandall, J; Chaparro, B; Ni, R; Cao, S

    2014-11-01

    Research indicates that using a cell phone to talk or text while maneuvering a vehicle impairs driving performance. However, few published studies directly compare the distracting effects of texting using a hands-free (i.e., speech-based interface) versus handheld cell phone, which is an important issue for legislation, automotive interface design and driving safety training. This study compared the effect of speech-based versus handheld text entries on simulated driving performance by asking participants to perform a car following task while controlling the duration of a secondary text-entry task. Results showed that both speech-based and handheld text entries impaired driving performance relative to the drive-only condition by causing more variation in speed and lane position. Handheld text entry also increased the brake response time and increased variation in headway distance. Text entry using a speech-based cell phone was less detrimental to driving performance than handheld text entry. Nevertheless, the speech-based text entry task still significantly impaired driving compared to the drive-only condition. These results suggest that speech-based text entry disrupts driving, but reduces the level of performance interference compared to text entry with a handheld device. In addition, the difference in the distraction effect caused by speech-based and handheld text entry is not simply due to the difference in task duration.

  19. 3D printed biomimetic whisker-based sensor with co-planar capacitive sensing

    NARCIS (Netherlands)

    Delamare, John; Sanders, Remco; Krijnen, Gijs

    2016-01-01

    This paper describes the development of a whisker sensor for tactile purposes and which is fabricated by 3D printing. Read-out consists of a capacitive measurement of a co-planar capacitance which is affected by a dielectric that is driven into the electric field of the capacitance. The current impl

  20. A branch-and-cut-and-price algorithm for the mixed capacitated general routing problem

    DEFF Research Database (Denmark)

    Bach, Lukas; Wøhlk, Sanne; Lysgaard, Jens

    2016-01-01

    In this paper, we consider the Mixed Capacitated General Routing Problem which is a combination of the Capacitated Vehicle Routing Problem and the Capacitated Arc Routing Problem. The problem is also known as the Node, Edge, and Arc Routing Problem. We propose a Branch-and-Cut-and-Price algorithm...

  1. 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

  2. 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

  3. Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia

    OpenAIRE

    Wilson, Rosamund J; Copley, J Brian

    2017-01-01

    Background Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. Scope A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent...

  4. [Microbial geochemical calcium cycle].

    Science.gov (United States)

    Zavarzin, G A

    2002-01-01

    The participation of microorganisms in the geochemical calcium cycle is the most important factor maintaining neutral conditions on the Earth. This cycle has profound influence on the fate of inorganic carbon, and, thereby, on the removal of CO2 from the atmosphere. The major part of calcium deposits was formed in the Precambrian, when prokaryotic biosphere predominated. After that, calcium recycling based on biogenic deposition by skeletal organisms became the main process. Among prokaryotes, only a few representatives, e.g., cyanobacteria, exhibit a special calcium function. The geochemical calcium cycle is made possible by the universal features of bacteria involved in biologically mediated reactions and is determined by the activities of microbial communities. In the prokaryotic system, the calcium cycle begins with the leaching of igneous rock predominantly through the action of the community of organotrophic organisms. The release of carbon dioxide to the soil air by organotrophic aerobes leads to leaching with carbonic acid and soda salinization. Under anoxic conditions, of major importance is the organic acid production by primary anaerobes (fermentative microorganisms). Calcium carbonate is precipitated by secondary anaerobes (sulfate reducers) and to a smaller degree by methanogens. The role of the cyanobacterial community in carbonate deposition is exposed by stromatolites, which are the most common organo-sedimentary Precambrian structures. Deposition of carbonates in cyanobacterial mats as a consequence of photoassimilation of CO2 does not appear to be a significant process. It is argued that carbonates were deposited at the boundary between the "soda continent", which emerged as a result of subaerial leaching with carbonic acid, and the ocean containing Ca2+. Such ecotones provided favorable conditions for the development of the benthic cyanobacterial community, which was a precursor of stromatolites.

  5. 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.

  6. 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.

  7. 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...... market entries made by Norwegian, Danish and Swedish firms suggests that the association between equity mode choice and non-location bound international experience diminishes in the presence of higher levels of multinational experience. Furthermore, firms whose entry mode choice is predicted by the model...... 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....

  8. 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...

  9. 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.

  10. 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...... compared to non-family firms. Furthermore, the Danish exporters regarded China as being the most established of the four BRIC markets which could be seen in their willingness to use high control entry modes in China. Finally, non-family firms are more concerned about higher flexibility and lower control...... 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....

  11. 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.

  12. 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...

  13. Hypersonic and planetary entry flight mechanics

    Science.gov (United States)

    Vinh, N. X.; Busemann, A.; Culp, R. D.

    1980-01-01

    The book treats hypersonic flight trajectories and atmospheric entry flight mechanics in light of their importance for space shuttle entry. Following a review of the structures of planetary atmospheres and aerodynamic forces, equations are derived for flight over a spherical planet, and the performance of long-range hypervelocity vehicles in extra-atmospheric flight is analyzed. Consideration is then given to vehicle trajectories in the powered and atmospheric reentry phases of flight, and several first-order solutions are derived for various planetary entry situations. The second-order theory of Loh for entry trajectories is presented along with the classical theories of Yaroshevskii and Chapman for entry into planetary atmospheres, and the thermal problems encountered in hypersonic flight are analyzed. A unified theory for entry into planetary atmospheres is then introduced which allows the performance of a general type of lifting vehicle to be studied, and applied to the analysis of orbit contraction due to atmospheric drag, flight with lift modulation and lateral maneuvers.

  14. Pulmonary Vascular Capacitance as a Predictor of Vasoreactivity in Idiopathic Pulmonary Arterial Hypertension Tested by Adenosine

    Directory of Open Access Journals (Sweden)

    Shafie

    2015-09-01

    Full Text Available Background Acute pulmonary vasoreactivity testing has been recommended in the diagnostic work-up of patients with idiopathic pulmonary arterial hypertension (IPAH. Pulmonary arteriolar capacitance (Cp approximated by stroke volume divided by pulmonary pulse pressure (SV/PP is considered as an independent predictor of mortality in patients with IPAH. Objectives We sought to evaluate any differences in baseline and adenosine Cp between vasoreactive and non-vasoreactive IPAH patients tested with adenosine. Patients and Methods Fourteen patients with IPAH and a vasoreactive adenosine vasoreactivity testing according to the ESC guidelines were compared with 24 IPAH patients with nonreactive adenosine test results. Results There were no statistical significant differences between the two groups regarding NYHA class, body surface area, heart rate, and systemic blood pressure during right heart catheterization. Hemodynamic study showed no statistical significant differences in cardiac output/Index, mean pulmonary artery pressure, pulmonary vascular resistance, and baseline Cp between the two groups. There was a statistical significant but weak increase in adenosine Cp in vasoreactive group compared to non-reactive group (P = 0.04. Multivariable analysis showed an association between Cp and vasoreactivity (Beta = 2, P = 0.04, OR = 0.05 (95%CI = 0.003 - 0.9. Conclusions Cp could be considered as an index for the prediction of vasoreactivity in patients with IPAH. Prediction of long-term response to calcium channel blockers in patients with IPAH and a positive vasoreactive test by this index should be addressed in further studies.

  15. Inositol trisphosphate and calcium signalling

    Science.gov (United States)

    Berridge, Michael J.

    1993-01-01

    Inositol trisphosphate is a second messenger that controls many cellular processes by generating internal calcium signals. It operates through receptors whose molecular and physiological properties closely resemble the calcium-mobilizing ryanodine receptors of muscle. This family of intracellular calcium channels displays the regenerative process of calcium-induced calcium release responsible for the complex spatiotemporal patterns of calcium waves and oscillations. Such a dynamic signalling pathway controls many cellular processes, including fertilization, cell growth, transformation, secretion, smooth muscle contraction, sensory perception and neuronal signalling.

  16. Planetary/DOD entry technology flight experiments. Volume 2: Planetary entry flight experiments

    Science.gov (United States)

    Christensen, H. E.; Krieger, R. J.; Mcneilly, W. R.; Vetter, H. C.

    1976-01-01

    The technical feasibility of launching a high speed, earth entry vehicle from the space shuttle to advance technology for the exploration of the outer planets' atmospheres was established. Disciplines of thermodynamics, orbital mechanics, aerodynamics propulsion, structures, design, electronics and system integration focused on the goal of producing outer planet environments on a probe shaped vehicle during an earth entry. Major aspects of analysis and vehicle design studied include: planetary environments, earth entry environment capability, mission maneuvers, capabilities of shuttle upper stages, a comparison of earth entry planetary environments, experiment design and vehicle design.

  17. The Impact of Vitamin D3 Supplementation on Mechanisms of Cell Calcium Signaling in Chronic Kidney Disease

    Directory of Open Access Journals (Sweden)

    Ingrid Lajdova

    2015-01-01

    Full Text Available Intracellular calcium concentration in peripheral blood mononuclear cells (PBMCs of patients with chronic kidney disease (CKD is significantly increased, and the regulatory mechanisms maintaining cellular calcium homeostasis are impaired. The purpose of this study was to examine the effect of vitamin D3 on predominant regulatory mechanisms of cell calcium homeostasis. The study involved 16 CKD stages 2-3 patients with vitamin D deficiency treated with cholecalciferol 7000–14000 IU/week for 6 months. The regulatory mechanisms of calcium signaling were studied in PBMCs and red blood cells. After vitamin D3 supplementation, serum concentration of 25(OHD3 increased (P<0.001 and [Ca2+]i decreased (P<0.001. The differences in [Ca2+]i were inversely related to differences in 25(OHD3 concentration (P<0.01. Vitamin D3 supplementation decreased the calcium entry through calcium release activated calcium (CRAC channels and purinergic P2X7 channels. The function of P2X7 receptors was changed in comparison with their baseline status, and the expression of these receptors was reduced. There was no effect of vitamin D3 on P2X7 pores and activity of plasma membrane Ca2+-ATPases. Vitamin D3 supplementation had a beneficial effect on [Ca2+]i decreasing calcium entry via CRAC and P2X7 channels and reducing P2X7 receptors expression.

  18. Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

    Science.gov (United States)

    Henrickson, Charles H.; Robinson, Paul R.

    1979-01-01

    The gravimetric determination of calcium as calcium carbonate is described. This experiment is suitable for undergraduate quantitative analysis laboratories. It is less expensive than determination of chloride as silver chloride. (BB)

  19. Calcium and Calcium Supplements: Achieving the Right Balance

    Science.gov (United States)

    ... bone mass, which is a risk factor for osteoporosis. Many Americans don't get enough calcium in their diets. Children and adolescent girls are at particular risk, but so are adults age 50 and older. How much calcium you ...

  20. Concentration Fluctuations and Capacitive Response in Dense Ionic Solutions

    CERN Document Server

    Uralcan, Betul; Debenedetti, Pablo G; Limmer, David T

    2016-01-01

    We use molecular dynamics simulations in a constant potential ensemble to study the effects of solution composition on the electrochemical response of a double layer capacitor. We find that the capacitance first increases with ion concentration following its expected ideal solution behavior but decreases upon approaching a pure ionic liquid. The non-monotonic behavior of the capacitance as a function of ion concentration results from the competition between the independent motion of solvated ions in the dilute regime and solvation fluctuations in the concentrated regime. When charge fluctuations induced by correlated ion-solvent fluctuations are large relative to those induced by the pure ionic liquid, such non-monotonic behavior is expected to be generic.

  1. Spin-orbit controlled capacitance of a polar heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Steffen, Kevin; Kopp, Thilo [Center for Electronic Correlations and Magnetism, EP VI, Institute of Physics, University of Augsburg, 86135 Augsburg (Germany); Loder, Florian [Center for Electronic Correlations and Magnetism, EP VI and TP III, Institute of Physics, University of Augsburg, 86135 Augsburg (Germany)

    2015-07-01

    Oxide heterostructures with polar films display special electronic properties, such as the electronic reconstruction at their internal interfaces with the formation of two-dimensional metallic states. Moreover, the electrical field from the polar layers is inversion-symmetry breaking and may generate a strong Rashba spin-orbit coupling (RSOC) in the interfacial electronic system. We investigate the capacitance of a heterostructure in which a strong RSOC at a metallic interface is controlled by the electric field of a surface electrode. Such a structure is for example given by a LaAlO{sub 3} film on a SrTiO{sub 3} substrate which is gated by a top electrode. We find that due to a strong RSOC the capacitance can be larger than the classical geometric value.

  2. Capacitated Vehicle Routing with Non-Uniform Speeds

    CERN Document Server

    Gortz, Inge Li; Nagarajan, Viswanath; Ravi, R

    2010-01-01

    The capacitated vehicle routing problem (CVRP) involves distributing (identical) items from a depot to a set of demand locations, using a single capacitated vehicle. We study a generalization of this problem to the setting of multiple vehicles having non-uniform speeds (that we call Heterogenous CVRP), and present a constant-factor approximation algorithm. The technical heart of our result lies in achieving a constant approximation to the following TSP variant (called Heterogenous TSP). Given a metric denoting distances between vertices, a depot r containing k vehicles with possibly different speeds, the goal is to find a tour for each vehicle (starting and ending at r), so that every vertex is covered in some tour and the maximum completion time is minimized. This problem is precisely Heterogenous CVRP when vehicles are uncapacitated. The presence of non-uniform speeds introduces difficulties for employing standard tour-splitting techniques. In order to get a better understanding of this technique in our con...

  3. Microbial desalination cell with capacitive adsorption for ion migration control.

    Science.gov (United States)

    Forrestal, Casey; Xu, Pei; Jenkins, Peter E; Ren, Zhiyong

    2012-09-01

    A new microbial desalination cell with capacitive adsorption capability (cMDC) was developed to solve the ion migration problem facing current MDC systems. Traditional MDCs remove salts by transferring ions to the anode and cathode chambers, which may prohibit wastewater beneficial reuse due to increased salinity. The cMDC uses adsorptive activated carbon cloth (ACC) as the electrodes and utilizes the formed capacitive double layers for electrochemical ion adsorption. The cMDC removed an average of 69.4% of the salt from the desalination chamber through electrode adsorption during one batch cycle, and it did not add salts to the anode or cathode chamber. It was estimated that 61-82.2mg of total dissolved solids (TDS) was adsorbed to 1g of ACC electrode. The cMDC provides a new approach for salt management, organic removal, and energy production. Further studies will be conducted to optimize reactor configuration and achieve in situ electrode regeneration.

  4. Leakage Currents and Capacitances of Thick CZT Detectors

    CERN Document Server

    Garson, Alfred; Jung, Ira V; Dowkontt, Paul; Bose, Richard; Simburger, Garry; Krawczynski, Henric

    2009-01-01

    The quality of Cadmium Zinc Telluride (CZT) detectors is steadily improving. For state of the art detectors, readout noise is thus becoming an increasingly important factor for the overall energy resolution. In this contribution, we present measurements and calculations of the dark currents and capacitances of 0.5 cm-thick CZT detectors contacted with a monolithic cathode and 8x8 anode pixels on a surface of 2 cm x 2 cm. Using the NCI ASIC from Brookhaven National Laboratory as an example, we estimate the readout noise caused by the dark currents and capacitances. Furthermore, we discuss possible additional readout noise caused by pixel-pixel and pixel-cathode noise coupling.

  5. Parameter optimization of temperature field in RF-capacitive hyperthermia

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To realize a certain target temperature distribution in tumor tissues and avoid over-heating in normal tissues in radio frequency (RF)-capacitive hyperthermia, an objective function and some weight coefficients are introduced. Then using the 2-D finite element method, the electromagnetic and bio-heat transfer equations are solved, and using the genetic algorithm the heating configurations are recursively modified to minimize the objective function. Finally an optimum solution of the expected heating field distribution in hyperthermia is achieved. And with a human heterogeneous tissue model extracted from X-ray CT images, satisfactory optimization results are obtained in the simulations on a biplate RF-capacitive hyperthermia device. This optimization technique for controlling the body temperature field has shown scientific importance and practical values in the research of hyperthermia.

  6. Sugar Cube Purity: Capacitive Sensing and Image Processing Approach

    Science.gov (United States)

    Madhumitha, S.; Rajath, R.; Venkatanathan, N.; Raajan, N. R.; Sridharan, M.

    2016-12-01

    Several methods have been implemented to find out if impurity is present in sugar cubes or powders so far. Several high end imaging techniques with X-ray scanners have been used to check the quality of the sugar. In this present study, without disturbing the physical nature of sugar, we have simply used the dielectric property analysis to check the purity of the sugar. This method can detect even infinitesimal amounts of impurity present in sugar with good accuracy. The positional accuracy is derived using artificial neural networks, which is been trained with various capacitance values when the impurity is present and gives the details on the change in capacitance value as the impurity position changes.

  7. OPTIMIZATION OF CAPACITATED VEHICLE ROUTING PROBLEM USING PSO

    Directory of Open Access Journals (Sweden)

    S.R.VENKATESAN

    2011-10-01

    Full Text Available This paper presents solution techniques for Capacitated Vehicle Routing Problem (CVRP using metaheuristics. Capacitated Vehicle Routing Problem is divided into set of customers called cluster, and find optimum travel distance of vehicle route. The CVRP is a combinatorial optimization problem; particle swarm optimization(PSO technique is adapted in this paper to solve this problem. The main problem is divided into subprograms/clusters and each subprogram is treated as travelling salesman problem and solved by usingparticle swarm optimization techniques (PSO. This paper presents a sweep, Clark and wright algorithm to form the clusters. This model is then solved by using a particle swarm optimization (PSO method to find optimum travel distance of vehicle route. Our analysis suggests that the proposed model enables users to establish route to serve all given customers with minimum distance of vehicles and maximum capacity.

  8. Composition change and capacitance properties of ruthenium oxide thin film

    Institute of Scientific and Technical Information of China (English)

    刘泓; 甘卫平; 刘仲武; 郑峰

    2015-01-01

    RuO2·nH2O film was deposited on tantalum foils by electrodeposition and heat treatment using RuCl3·3H2O as precursor. Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·nH2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2 h, RuO2·nH2O electrode surface gains mass of 2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly 20%with voltage scan rate increasing from 5 to 250 mV/s.

  9. Capacitance of a passive iron electrode in acidic solutions

    Energy Technology Data Exchange (ETDEWEB)

    Grilikhes, M.S.; Berezin, M.Yu.; Gorlin, A.V.; Sapelova, E.V.; Sokolov, M.A.; Sukhotin, A.M.

    1985-12-01

    In the present work the authors measured the capacitance of the electrical double layer on passive Armco iron in acidic solutions with the simultaneous recording of the potentiodynamic curves. The measurements were carried out on an apparatus which is based on the double-pulse variant of the galvanostatic method with a pulse lifetime of 2 microseconds, in which the influence of the faradic processes on the capacitance curves is negligibly small in the case of electrochemical systems with small exchange currents. The experiments were carried out at room temperature in 0.5 M sulfuric acid (pH 0.25) and 0.5 M tartaric acid H/sub 2/C/sub 4/H/sub 4/O/sub 6/ (pH 1.6).

  10. Capacitance Variation of Electrolyte-Gated Bilayer Graphene Based Transistors

    Directory of Open Access Journals (Sweden)

    Hediyeh Karimi

    2013-01-01

    Full Text Available Quantum capacitance of electrolyte-gated bilayer graphene field-effect transistors is investigated in this paper. Bilayer graphene has received huge attention due to the fact that an energy gap could be opened by chemical doping or by applying external perpendicular electric field. So, this extraordinary property can be exploited to use bilayer graphene as a channel in electrolyte-gated field-effect transistors. The quantum capacitance of bi-layer graphene with an equivalent circuit is presented, and also based on the analytical model a numerical solution is reported. We begin by modeling the DOS, followed by carrier concentration as a function V in degenerate and nondegenerate regimes. To further confirm this viewpoint, the presented analytical model is compared with experimental data, and acceptable agreement is reported.

  11. High resolution capacitance detection circuit for rotor micro-gyroscope

    Directory of Open Access Journals (Sweden)

    Ming-Yuan Ren

    2014-03-01

    Full Text Available Conventional methods for rotor position detection of micro-gyroscopes include common exciting electrodes (single frequency and common sensing electrodes (frequency multiplex, but they have encountered some problems. So we present a high resolution and low noise pick-off circuit for micro-gyroscopes which utilizes the time multiplex method. The detecting circuit adopts a continuous-time current sensing circuit for capacitance measurement, and its noise analysis of the charge amplifier is introduced. The equivalent output noise power spectral density of phase-sensitive demodulation is 120 nV/Hz1/2. Tests revealed that the whole circuitry has a relative capacitance resolution of 1 × 10−8.

  12. Capacitated Vehicle Routing with Non-Uniform Speeds

    DEFF Research Database (Denmark)

    Gørtz, Inge Li; Molinaro, Marco; Nagarajan, Viswanath

    2011-01-01

    The capacitated vehicle routing problem (CVRP) [21] involves distributing (identical) items from a depot to a set of demand locations in the shortest possible time, using a single capacitated vehicle. We study a generalization of this problem to the setting of multiple vehicles having non-uniform...... vehicles having speeds {λ i } i = 1 k , the goal is to find a tour for each vehicle (starting and ending at r), so that every vertex is covered in some tour and the maximum completion time is minimized. This problem is precisely Heterogenous CVRP when vehicles are uncapacitated. The presence of non-uniform...... the introduction of a new approximate MST construction called Level-Prim, which is related to Light Approximate Shortest-path Trees [18]. The last component of our algorithm involves partitioning the Level-Prim tree and matching the resulting parts to vehicles. This decomposition is more subtle than usual since...

  13. A High-Stability Capacitance Sensor System and Its Evaluation

    Science.gov (United States)

    2008-12-01

    15:45 from IEEE Xplore . Restrictions apply. Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of...45 from IEEE Xplore . Restrictions apply. AVRAMOV-ZAMUROVIC AND LEE: HIGH-STABILITY CAPACITANCE SENSOR SYSTEM AND ITS EVALUATION 957 Fig. 4...Authorized licensed use limited to: US Naval Academy. Downloaded on May 13, 2009 at 15:45 from IEEE Xplore . Restrictions apply. 958 IEEE TRANSACTIONS

  14. Simulation of New Switched Capacitance Power Converter for Srm

    Directory of Open Access Journals (Sweden)

    S. M. Mohamed Saleem

    2014-06-01

    Full Text Available In this paper, design and simulation of switched capacitance power converter are proposed for 6/4 switched reluctance motor (SRM drive. The operating principle and design consideration of the proposed converter is explained. The proposed converter performance is better in reduction of torque ripple and constant speed can be achieved quickly with reduced power loss when compared with asymmetric converter. The proposed system is simulated by using MATLAB Simulink and their results are clearly presented.

  15. Enhanced Capacitive Characteristics of Activated Carbon by Secondary Activation

    Institute of Scientific and Technical Information of China (English)

    YANG Hui; LU Tian-hong; Yoshio Masaki

    2004-01-01

    The effect of the improvement of commercial activated carbon(AC) on its specific capacitance and high rate capability of double layer(dl) charging/discharging process has been studied. The improvement of AC was carried out via a secondary activation under steam in the presence of catalyst NiCl2, and the suitable condition was found to be a heat treatment at about 875 ℃ for 1 h. Under those conditions, the discharge specific capacitance of the improved AC increases up to 53.67 F/g, showing an increase of about 25% as compared with that of as-received AC. The good rectangular-shaped voltammograms and A.C. impedance spectra prove that the high rate capability of the capacitor made of the improved AC is enhanced significantly. The capacitance resistance(RC) time constant of the capacitor containing the improved AC is 1.74 s, which is much lower than that of the one containing as-received AC(an RC value of 4. 73 s). It is noted that both kinds of AC samples show a similar specific surface area and pore size distribution, but some changes have taken place in the carbon surface groups, especially a decrease in the concentration of surface carbonyl groups after the improvement, which have been verified by means of X-photoelectron spectroscopy. Accordingly, it is suggested that the decrease in the concentration of surface carbonyl groups for the improved AC is beneficial to the organic electrolyte ion penetrating into the pores, thus leading to the increase in both the specific capacitance and high rate capability of the supercapacitor.

  16. Computation of Capacitance for MEMS Comb-Drive Structures

    Institute of Scientific and Technical Information of China (English)

    LI Ming-hui; GAO Shi-qiao; LIU Hai-peng; LIANG Xin-jian

    2009-01-01

    According to the characteristics of comb-drive structures,the electrical potential field is analyzed;the model based on corner capacitor is presented and solved with the capacitance characteristic formula of nonlinear capacitor.Compared with the results of finite element method simulation,the model based on corner capacitor is more accurate than the models based on infinite parallel plate capacitor and parallel plate capacitor with edge effects,

  17. A Capacitated Facility Location Approach for the Tanker Employment Problem

    Science.gov (United States)

    2005-03-01

    Depot (MD) Vehicle Routing Problem (VRP) ......................................... 14 2.5 Capacitated Facility Location Problem (CFLP) with Sole...service receiver groups. In this sense the problem can be viewed as a multi-depot vehicle routing problem . Anchor points are two stationary points...for future research. 2.4 Multi-Depot (MD) Vehicle Routing Problem (VRP) Another approach to the Tanker Employment Problem is to model it as a VRP

  18. Capacitive technology for energy extraction from chemical potential differences

    OpenAIRE

    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.   Chapter 2 introduces the principle and initial tests. The entropy increase of mixing two solutions of different salt concentrations can be harnessed to generate electrical energy. Worldwide, the potent...

  19. Managing periodic review inventory systems with capacitated replenishments

    OpenAIRE

    B. RAA; Dubois, T.; Dullaert, W

    2011-01-01

    This paper studies periodic review inventory systems in which replenishments are capacitated. This capacity restriction implies that the order-up-to level may not always be reached at each replenishment, such that additional safety stock is needed to achieve the same service level as in the uncapacitated case usually assumed in the existing literature. To determine the required level of safety stock, and hence the order-up-to level, an iterative procedure is proposed which can be adjusted to ...

  20. DNA Nucleotides Detection via capacitance properties of Graphene

    Science.gov (United States)

    Khadempar, Nahid; Berahman, Masoud; Yazdanpanah, Arash

    2016-05-01

    In the present paper a new method is suggested to detect the DNA nucleotides on a first-principles calculation of the electronic features of DNA bases which chemisorbed to a graphene sheet placed between two gold electrodes in a contact-channel-contact system. The capacitance properties of graphene in the channel are surveyed using non-equilibrium Green's function coupled with the Density Functional Theory. Thus, the capacitance properties of graphene are theoretically investigated in a biological environment, and, using a novel method, the effect of the chemisorbed DNA nucleotides on electrical charges on the surface of graphene is deciphered. Several parameters in this method are also extracted including Electrostatic energy, Induced density, induced electrostatic potential, Electron difference potential and Electron difference density. The qualitative and quantitative differences among these parameters can be used to identify DNA nucleotides. Some of the advantages of this approach include its ease and high accuracy. What distinguishes the current research is that it is the first experiment to investigate the capacitance properties of gaphene changes in the biological environment and the effect of chemisorbed DNA nucleotides on the surface of graphene on the charge.

  1. Capacitance-modulated transistor detects odorant binding protein chiral interactions

    Science.gov (United States)

    Mulla, Mohammad Yusuf; Tuccori, Elena; Magliulo, Maria; Lattanzi, Gianluca; Palazzo, Gerardo; Persaud, Krishna; Torsi, Luisa

    2015-01-01

    Peripheral events in olfaction involve odorant binding proteins (OBPs) whose role in the recognition of different volatile chemicals is yet unclear. Here we report on the sensitive and quantitative measurement of the weak interactions associated with neutral enantiomers differentially binding to OBPs immobilized through a self-assembled monolayer to the gate of an organic bio-electronic transistor. The transduction is remarkably sensitive as the transistor output current is governed by the small capacitance of the protein layer undergoing minute changes as the ligand-protein complex is formed. Accurate determination of the free-energy balances and of the capacitance changes associated with the binding process allows derivation of the free-energy components as well as of the occurrence of conformational events associated with OBP ligand binding. Capacitance-modulated transistors open a new pathway for the study of ultra-weak molecular interactions in surface-bound protein-ligand complexes through an approach that combines bio-chemical and electronic thermodynamic parameters.

  2. Ring VCO Design with Variable Capacitance XNOR Delay Cell

    Science.gov (United States)

    Kumar, Manoj; Arya, Sandeep; Pandey, Sujata

    2015-12-01

    This paper presents the new designs of voltage controlled oscillator (VCO) with three transistors XNOR gate as variable capacitive load. Design of three, five and seven stage VCO have been reported using single ended ring topology. CMOS inverter based delay cell is modified with addition of XNOR capacitive load. Output frequency has been controlled by applied voltage to variable capacitive load. Control voltage of VCO has been varied from 1.3 to 2.1 V. Three stage VCO provides output frequency variation in the range of 3.52-3.34 GHz with power consumption variation from 0.81 to 1.76 mW. Five stage VCO shows frequency variation from 2.06 to 1.98 GHz with power consumption varying from 1.35 to 2.94 mW. Moreover, frequency of seven stage VCO varies from 1.47 to 1.41 GHz with varying power from 1.89 to 4.12 mW. Power consumption and output frequency of proposed VCO circuits have been compared with earlier reported circuits and present approach shows considerable improvements.

  3. Investigation of capacitively coupled ultrasonic transducer system for nondestructive evaluation.

    Science.gov (United States)

    Zhong, Cheng Huan; Wilcox, Paul D; Croxford, Anthony J

    2013-12-01

    Capacitive coupling offers a simple solution to wirelessly probe ultrasonic transducers. This paper investigates the theory, feasibility, and optimization of such a capacitively coupled transducer system (CCTS) in the context of nondestructive evaluation (NDE) applications. The noncontact interface relies on an electric field formed between four metal plates-two plates are physically connected to the electrodes of a transducer, the other two are in a separate probing unit connected to the transmit/receive channel of the instrumentation. The complete system is modeled as an electric network with the measured impedance of a bonded piezoelectric ceramic disc representing a transducer attached to an arbitrary solid substrate. A transmission line model is developed which is a function of the physical parameters of the capacitively coupled system, such as the permittivity of the material between the plates, the size of the metal plates, and their relative positions. This model provides immediate prediction of electric input impedance, pulse-echo response, and the effect of plate misalignment. The model has been validated experimentally and has enabled optimization of the various parameters. It is shown that placing a tuning inductor and series resistor on the transmitting side of the circuit can significantly improve the system performance in terms of the signal-to-crosstalk ratio. Practically, bulk-wave CCTSs have been built and demonstrated for underwater and through-composite testing. It has been found that electrical conduction in the media between the plates limits their applications.

  4. Capacitive-coupled Series Spoof Surface Plasmon Polaritons

    Science.gov (United States)

    Yin, Jia Yuan; Ren, Jian; Zhang, Hao Chi; Zhang, Qian; Cui, Tie Jun

    2016-04-01

    A novel method to realize stopband within the operating frequency of spoof surface plasmon polaritons (SPPs) is presented. The stopband is introduced by a new kind of capacitive-coupled series spoof SPPs. Two conventional H-shaped unit cells are proposed to construct a new unit cell, and every two new unit cells are separated by a gap with certain distance, which is designed to implement capacitive coupling. The original surface impedance matching is disturbed by the capacitive coupling, leading to the stopband during the transmission of SPPs. The proposed method is verified by both numerical simulations and experiments, and the simulated and measured results have good agreements. It is shown that the proposed structure exhibits a stopband in 9-9.5 GHz while the band-pass feature maintains in 5-9 GHz and 9.5-11 GHz. In the passband, the reflection coefficient is less than -10 dB, and the transmission loss is around 3 dB in the stopband, the reflection coefficient is -2 dB, and the transmission coefficient is less than -30 dB. The compact size, easy fabrication and good band-pass and band-stop features make the proposed structure a promising plasmonic device in SPP communication systems.

  5. Capacitive properties of polypyrrole/activated carbon composite

    Directory of Open Access Journals (Sweden)

    Porjazoska-Kujundziski Aleksandra

    2014-01-01

    Full Text Available Electrochemical synthesis of polypyrrole (PPy and polypyrrole / activated carbon (PPy / AC - composite films, with a thickness between 0.5 and 15 μm were performed in a three electrode cell containing 0.1 mol dm-3 Py, 0.5 mol dm-3 NaClO4 dissolved in ACN, and dispersed particles of AC (30 g dm-3. Electrochemical characterization of PPy and PPy / AC composites was performed using cyclic voltammetry (CV and electrochemical impedance spectroscopy (EIS techniques. The linear dependences of the capacitance (qC, redox capacitance (qred, and limiting capacitance (CL of PPy and PPy / AC - composite films on their thickness (L, obtained by electrochemical and impedance analysis, indicate a nearly homogeneous distribution of the incorporated AC particles in the composite films (correlation coefficient between 0.991 and 0.998. The significant enhancement of qC, qred, and CL, was observed for composite films (for ∼40 ± 5% in respect to that of the “pure” PPy. The decreased values of a volume resistivity in the reduced state of the composite film, ρ = 1.3 ⋅ 106 Ω cm (for L = 7.5 μm, for two orders of magnitude, compared to that of PPy - film with the same thickness, ρ ∼ 108 Ω cm, was also noticed.

  6. Can a Pressure Standard be Based on Capacitance Measurements?

    Science.gov (United States)

    Moldover, Michael R

    1998-01-01

    We consider the feasibility of basing a pressure standard on measurements of the dielectric constant ϵ and the thermodynamic temperature T of helium near 0 °C. The pressure p of the helium would be calculated from fundamental constants, quantum mechanics, and statistical mechanics. At present, the relative standard uncertainty of the pressure ur(p) would exceed 20 × 10(-6), the relative uncertainty of the value of the molar polarizability of helium Aϵ calculated ab initio. If the relativistic corrections to Aϵ were calculated as accurately as the classical value is now known, a capacitance-based pressure standard might attain ur(p) < 6 × 10(-6) for pressures near 1 MPa, a result of considerable interest for pressure metrology. One obtains p by eliminating the density from the virial expansions for p and ϵ - 1. If ϵ - 1 were measured with a very stable, 0.5 pF toroidal cross capacitor, the small capacitance and the small values of ϵ - 1 would require state-of-the-art capacitance measurements to achieve a useful pressure standard.

  7. Investigation on the Sensitivity Distribution in Electrical Capacitance Tomography System

    Directory of Open Access Journals (Sweden)

    Pan Jiang

    2013-07-01

    Full Text Available The gas-solid-liquid three-phase flow is a very complicated flow pattern in pipeline transportation. By using electrical capacitance tomography (ETC it can acquire the permittivity distribution of the multi-phase. The sensitivity distribution in ETC may affect the analysis of the permittivity distribution of the multi-phase. However, very limited work has been done in this issue. In order to investigate the sensitivity distribution in ETC, this paper employs the finite element method (FEM to establish the principle and components of ECT. The FEM model of the sensitivity distribution as a function of the inter-electrode capacitance was discussed. Simulation tests were carried out to calculate the charge on the electrode pairs to access the potential distribution of the ETC. The analysis results show that the dielectric have great influence on the capacitance value and small distance between the electrode pair and the sensitivity field will produce high sensitivity value. Hence, the findings of this work can provide reference for the design of ECT in practice.

  8. 19 CFR 142.44 - Entry number range.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Entry number range. 142.44 Section 142.44 Customs... (CONTINUED) ENTRY PROCESS Line Release § 142.44 Entry number range. After an application for Line Release has received final approval, filers must provide the port director, in writing, with a range of entry...

  9. 77 FR 5681 - Establishment of Global Entry Program

    Science.gov (United States)

    2012-02-06

    ... assist in developing a marketing strategy. The firm has created a new Global Entry logo and tag line... SENTRI II. Analysis of Comments A. Program Performance and Entry Process B. Marketing of Global Entry C.... Marketing of Global Entry Comment: CBP received two comments suggesting that CBP should expand marketing...

  10. 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...

  11. Calcium and the damage pathways in muscular dystrophy.

    Science.gov (United States)

    Allen, David G; Gervasio, Othon L; Yeung, Ella W; Whitehead, Nicholas P

    2010-02-01

    Duchenne muscular dystrophy (DMD) is a severe muscle-wasting disease caused by the absence of the cytoskeletal protein dystrophin. Experiments on the mdx mouse, a model of DMD, have shown that mdx muscles are particularly susceptible to stretch-induced damage. In this review, we discuss evidence showing that a series of stretched contractions of mdx muscle fibres causes a prolonged increase in resting intracellular calcium concentration ([Ca2+]i). The rise in [Ca2+]i is caused by Ca2+ entry through a class of stretch-activated channels (SACNSC) for which one candidate gene is TRPC1. We review the evidence for activation of SACNSC in muscle by reactive oxygen species (ROS) and suggest that stretch-induced ROS production is part of the pathway that triggers increased channel activity. When the TRPC1 gene was transfected into C2 myoblasts, expression occurred throughout the cell. Only when the TRPC1 gene was coexpressed with caveolin-3 did the TRPC1 protein express in the membrane. When TRPC1 was expressed in the membrane, it could be activated by ROS to produce Ca2+ entry and this entry was inhibited by PP2, an inhibitor of src kinase. These results suggest that stretched contractions activate ROS production, which activates src kinase. Activity of this kinase causes opening of SACNSC and allows Ca2+ entry. This pathway appears to be a significant cause of muscle damage in DMD.

  12. Calcium, vitamin D and bone

    OpenAIRE

    Borg, Andrew A.

    2012-01-01

    Calcium, protein and vitamin D are the main nutrients relevant to bone health. This short article discusses the importance of vitamin D and its relation to calcium homeostasis. The various causes, clinical manifestations and treatment are outlined.

  13. 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

  14. Calcium carbonate overdose

    Science.gov (United States)

    Calcium carbonate is not very poisonous. Recovery is quite likely. But, long-term overuse is more serious than a single overdose, because it can cause kidney damage. Few people die from an antacid overdose. Keep all medicines in child-proof bottles and out ...

  15. High Blood Calcium (Hypercalcemia)

    Science.gov (United States)

    ... as well as kidney function and levels of calcium in your urine. Your provider may do other tests to further assess your condition, such as checking your blood levels of phosphorus (a mineral). Imaging studies also may be helpful, such as bone ...

  16. 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 500...

  17. Lessons learned from planetary entry probe missions

    Science.gov (United States)

    Niemann, Hasso; Atreya, Sushil K.; Kasprzak, Wayne

    Probing the atmospheres and surfaces of the planets and their moons with fast moving entry probes has been a very useful and essential technique to obtain in situ or quasi in situ scientific data (ground truth) which could not otherwise be obtained from fly by or orbiter only missions and where balloon, aircraft or lander missions are too complex and too costly. Planetary entry probe missions have been conducted successfully on Venus, Mars, Jupiter and Titan after having been first demonstrated in the Earth's atmosphere. Future planetary missions should also include more entry probe missions back to Venus and to the outer planets. The success of and science returns from past missions, the need for more and unique data, and a continuously advancing technology generate confidence that future missions will be even more successful with respect to science return and technical performance. There are, however, unique challenges associated with entry probe missions and with building instruments for an entry probe, as compared to orbiters, landers, or rovers. Conditions during atmospheric entry are extreme. There are operating time constraints due to the usually short duration of the probe descent, and the instruments experience rapid environmental changes in temperature and pressure. In addition, there are resource limitations, i.e. mass, power, size and bandwidth. Because of the protective heat shield and the high acceleration the probe experiences during entry, the ratio of payload to total probe mass is usually much smaller than in other missions. Finally, the demands on the instrument design are determined in large part by conditions (pressure, temperature, composition) unique to the particular body under study, and as a result, there is no one-size-fits-all instrument for an atmospheric probe. Many of these requirements are more easily met by miniaturizing the probe instrumentation and consequently reducing the required size of the probe. Improved heat shield

  18. 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.

  19. 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.

  20. 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

  1. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...

  2. 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.

  3. 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.

  4. Shuttle program. MCC Level C formulation requirements: Entry guidance and entry autopilot

    Science.gov (United States)

    Harpold, J. C.; Hill, O.

    1980-01-01

    A set of preliminary entry guidance and autopilot software formulations is presented for use in the Mission Control Center (MCC) entry processor. These software formulations meet all level B requirements. Revision 2 incorporates the modifications required to functionally simulate optimal TAEM targeting capability (OTT). Implementation of this logic in the MCC must be coordinated with flight software OTT implementation and MCC TAEM guidance OTT. The entry guidance logic is based on the Orbiter avionics entry guidance software. This MCC requirements document contains a definition of coordinate systems, a list of parameter definitions for the software formulations, a description of the entry guidance detailed formulation requirements, a description of the detailed autopilot formulation requirements, a description of the targeting routine, and a set of formulation flow charts.

  5. Bioceramics of calcium orthophosphates.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2010-03-01

    A strong interest in use of ceramics for biomedical applications appeared in the late 1960's. Used initially as alternatives to metals in order to increase a biocompatibility of implants, bioceramics have become a diverse class of biomaterials, presently including three basic types: relatively bioinert ceramics, bioactive (or surface reactive) and bioresorbable ones. Furthermore, any type of bioceramics could be porous to provide tissue ingrowth. This review is devoted to bioceramics prepared from calcium orthophosphates, which belong to the categories of bioresorbable and bioactive compounds. During the past 30-40 years, there have been a number of major advances in this field. Namely, after the initial work on development of bioceramics that was tolerated in the physiological environment, emphasis was shifted towards the use of bioceramics that interacted with bones by forming a direct chemical bond. By the structural and compositional control, it became possible to choose whether the bioceramics of calcium orthophosphates was biologically stable once incorporated within the skeletal structure or whether it was resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics, which is able to regenerate bone tissues, has been developed. Current biomedical applications of calcium orthophosphate bioceramics include replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Potential future applications of calcium orthophosphate bioceramics will include drug-delivery systems, as well as they will become effective carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes.

  6. The molecular choreography of a store-operated calcium channel.

    Science.gov (United States)

    Lewis, Richard S

    2007-03-15

    Store-operated calcium channels (SOCs) serve essential functions from secretion and motility to gene expression and cell growth. A fundamental mystery is how the depletion of Ca2+ from the endoplasmic reticulum (ER) activates Ca2+ entry through SOCs in the plasma membrane. Recent studies using genetic approaches have identified genes encoding the ER Ca2+ sensor and a prototypic SOC, the Ca2+-release-activated Ca2+ (CRAC) channel. New findings reveal a unique mechanism for channel activation, in which the CRAC channel and its sensor migrate independently to closely apposed sites of interaction in the ER and the plasma membrane.

  7. 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.

  8. Mitochondrial modulation of store-operated Ca(2+) entry in model cells of Alzheimer's disease.

    Science.gov (United States)

    Ma, Tuo; Gong, Kai; Yan, Yufang; Song, Bo; Zhang, Xiufang; Gong, Yandao

    2012-09-21

    Mitochondrial malfunction and calcium dyshomeostasis are early pathological events considered as important features of the Alzheimer's disease (AD) brain. Recent studies have suggested mitochondrion as an active regulator of Ca(2+) signaling based on its calcium buffering capacity. Herein, we investigated the mitochondrial involvement in the modulation of store-operated calcium entry (SOCE) in neural 2a (N2a) transgenic AD model cells. Results showed that SOCE was significantly depressed in N2a cells transfected with wild-type human APP695 (N2a APPwt) compared with empty vector control (N2a WT) cells. Pharmacological manipulation with mitochondrial function blockers, such as FCCP, RuR, or antimycin A/oligomycin, could inhibit mitochondrial calcium handling, and then impair SOCE pathway in N2a WT cells. Furthermore, mitochondria of N2a APPwt cells exhibited more severe swelling in response to Ca(2+), which is an indication of mitochondrial membrane permeability transition (MPT), than the wild-type controls. Additionally, treatment with cyclosporin A, a potent inhibitor of cyclophilin D, which can block MPT, could significantly restore the attenuated SOCE in N2a APPwt cells. Therefore, inhibition of cyclophilin D might be a therapeutic strategy for Alzheimer's disease.

  9. Theoretical study of quantum capacitance and associated delay in armchair-edge graphene nanoribbons

    Science.gov (United States)

    Hassan, Asif; Hossain, Md. Faruque; Rana, Md. Sohel; Kouzani, Abbas Z.

    2015-09-01

    This work presents a comprehensive investigation of the quantum capacitance and the associated effects on the carrier transit delay in armchair-edge graphene nanoribbons (A-GNRs) based on semi-analytical method. We emphasize on the realistic analysis of bandgap with taking edge effects into account by means of modified tight binding (TB) model. The results show that the edge effects have significant influence in defining the bandgap which is a necessary input in the accurate analyses of capacitance. The quantum capacitance is discussed in both nondegenerate (low gate voltage) and degenerate (high gate voltage) regimes. We observe that the classical capacitance limits the total gate (external) capacitance in the degenerate regime, whereas, quantum capacitance limits the external gate capacitance in the nondegenerate regime. The influence of gate capacitances on the gate delay is studied extensively to demonstrate the optimization of switching time. Moreover, the high-field behavior of a GNR is studied in the degenerate and nondegenerate regimes. We find that a smaller intrinsic capacitance appears in the channel due to high velocity carrier, which limits the quantum capacitance and thus limit the gate delay. Such detail analysis of GNRs considering a realistic model would be useful for the optimized design of GNR-based nanoelectronic devices.

  10. A simple efficient model of parasitic capacitances of deep-submicron LDD MOSFETs

    Science.gov (United States)

    Prégaldiny, Fabien; Lallement, Christophe; Mathiot, Daniel

    2002-12-01

    Estimation of parasitic capacitances in a MOSFET device is very important, notably in mixed circuit simulation. For deep-submicron LDD MOSFETs, the extrinsic capacitance (overlap plus fringing capacitances) is a growing fraction of the total gate capacitance. A correct estimation of the extrinsic capacitance requires an accurate modeling of each of its constituents. However the major existing models do not correctly predict the overlap capacitance and the inner fringing capacitance (which is often ignored). In this paper a new approach to model the overlap Cov and fringing Cif+ Cof capacitances in the zero-current regime is presented. The bias dependence of the extrinsic capacitance is investigated and a detailed study of the influence of the LDD doping dose is also undertaken. Then, an efficient, simple and continuous model describing the evolution of overlap and fringing capacitances in all operating regimes of a n-channel LDD MOSFET is developed. Finally this model is incorporated in an existing compact-model for circuit simulation. It is shown that this new model leads to excellent results in comparison with full 2D numerical device simulation.

  11. 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...... 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...... are identified. The paper closes with a brief discussion of limitations, avenues for future research, and implications for managers and affected policymakers....

  12. Project Prometheus and Future Entry Probe Missions

    Science.gov (United States)

    Spilker, Thomas R.

    2005-01-01

    A viewgraph presentation on project Prometheus and future entry probe missions is shown. The topics include: 1) What Is Project Prometheus?; 2) What Capabilities Can Project Prometheus Offer? What Mission Types Are Being Considered?; 3) Jupiter Icy Moons Orbiter (JIMO); 4) How Are Mission Opportunities Changing?; 5) Missions Of Interest a Year Ago; 6) Missions Now Being Considered For Further Study; 7) Galileo-Style (Conventional) Probe Delivery; 8) Galileo-Style Probe Support; 9) Conventional Delivery and Support of Multiple Probes; 10) How Entry Probe Delivery From an NEP Vehicle Is Different; and 11) Concluding Remarks.

  13. Automated Re-Entry System using FNPEG

    Science.gov (United States)

    Johnson, Wyatt R.; Lu, Ping; Stachowiak, Susan J.

    2017-01-01

    This paper discusses the implementation and simulated performance of the FNPEG (Fully Numerical Predictor-corrector Entry Guidance) algorithm into GNC FSW (Guidance, Navigation, and Control Flight Software) for use in an autonomous re-entry vehicle. A few modifications to FNPEG are discussed that result in computational savings -- a change to the state propagator, and a modification to cross-range lateral logic. Finally, some Monte Carlo results are presented using a representative vehicle in both a high-fidelity 6-DOF (degree-of-freedom) sim as well as in a 3-DOF sim for independent validation.

  14. Form, its meaning, and dictionary entries

    Directory of Open Access Journals (Sweden)

    Violetta Koseska-Toszewa

    2015-11-01

    It is worth stressing that distinguishing between the form and its meaning in comparing the material 6 languages belonging to three different groups of Slavic languages (as is the case in the MONDILEX Project will allow us to avoid numeorus substantiva mistakes and erroneous conclusions. Hence dictionary entries should be verified and made uniform in that respect before they are “digitalized”... Distinction between the form and its meaning in a dictionary entry is fully possible, as shown by works of Z. Saloni (2002 and A.Przepiórkowski (2008.

  15. 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.

  16. Depleted internal store-activated Ca2+ entry can trigger neurotransmitter release in bovine chromaffin cells.

    Science.gov (United States)

    Powis, D A; Clark, C L; O'Brien, K J

    1996-02-09

    A potential role of the intracellular Ca2+ stores in modulating catecholamine release has been investigated in bovine chromaffin cells maintained in tissue culture. Pharmacological depletion of the stores with a combination of caffeine, histamine and thapsigargin in Ca2+-free media resulted in a significantly greater release of catecholamines on re-exposure to Ca2+-containing media compared with that from non-store depleted cells. The increase in catecholamine release was prevented by intracellular BAPTA indicating that the increase was caused by a rise in Ca2+. Measurement of intracellular free Ca2+ concentration with the fluorescent indicator, fura-2, over the same time-course as the catecholamine release experiments showed that upon restoration of external Ca2+ there was an immediate, substantial and maintained increase in cytosolic Ca2+. It is most probable that the increase in catecholamine release was a consequence of an increase in Ca2+ influx triggered by prior depletion of the internal Ca2+ stores. However, the data suggest that capacitative Ca2+ entry is poorly linked to catecholamine release; although Ca2+ entry on restoration of external Ca2+ was immediate and substantial, the increase in catecholamine release, although quantitatively significant, was slowly realised.

  17. Dynamic quantification of intracellular calcium and protein tyrosine phosphorylation in cryopreserved boar spermatozoa during short-time incubation with oviductal fluid.

    Science.gov (United States)

    Kumaresan, A; González, R; Johannisson, A; Berqvist, A-S

    2014-11-01

    Freshly ejaculated boar spermatozoa require several hours of exposure to capacitating conditions to undergo capacitation. We hypothesized that cryopreserved boar spermatozoa might elicit a capacitation response after a relatively shorter time of exposure to capacitating conditions. Washed, frozen-thawed boar spermatozoa were incubated separately with pre-ovulatory isthmic oviductal fluid (EODF), post-ovulatory ODF (MODF), capacitation medium (CM), and noncapacitating medium (NCM) for 60 minutes. Aliquots of spermatozoa were taken at 0, 5, 15, 30, and 60 minutes during incubation and sperm kinematics, intracellular calcium [Ca2(+)]i content, and protein tyrosine phosphorylation (PTP) were studied. The proportion of motile spermatozoa increased significantly after 5 minutes of incubation with EODF. A similar increase was not observed in the other groups. During the initial 5 minutes of incubation, the proportion of spermatozoa with high [Ca(2+)]i decreased significantly in all four groups. The proportion of tyrosine phosphorylated spermatozoa increased from 6.49 ± 1.93% to 15.42 ± 3.58% and 18.41 ± 1.57% in EODF and MODF groups, respectively, at 5 minutes of incubation. Neither CM nor NCM elicited any immediate effect on PTP in spermatozoa. There was a positive and significant correlation between [Ca(2+)]i and sperm motility (P = 0.009). It may be concluded that frozen-thawed boar spermatozoa undergo capacitation-associated changes after a relatively short exposure to EODF, and there are some subpopulations of spermatozoa that undergo PTP despite possessing low [Ca(2+)]i.

  18. 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

  19. Position-optimization on retained entry and backfilling wall in gob-side entry retaining techniques

    Institute of Scientific and Technical Information of China (English)

    Xiaowei Feng; Nong Zhang

    2015-01-01

    This study investigates the stability problem of gob-side entry retaining (GER) and backfilling wall which located under the key block B. Based on the combined research of elastic–plastic mechanics, structure mechanics and modern theory of mining-induced pressure, the caving characteristic and roof structure over the GER were analyzed, and the vertical force and the torque on retained entry roof were also derived as the position for the retained entry varies. On the basis of the specific geology in Huainan mining area, the results indicate that a relatively more stable position for retained entry neighbors the hinge point of block A and B, and it also located at a scope ranging from this point to the one-third length of block B in horizontal direction. As to appropriate position for backfilling wall, this study recommends partial-road-in backfilling method for GER. Field trial conducted at panel face 12418 of Xieqiao Mine demonstrates that the recommended width for original entry is 3.6 m and the preferred width proportion between original retained entry and original entry is 75%or so whereas the avoidable one is 88%or so. These findings provide qualitative references to the mines which share similar geology as what Huainan mining area characterized.

  20. 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.

  1. A robust parasitic-insensitive successive approximation capacitance-to-digital converter

    KAUST Repository

    Omran, Hesham

    2014-09-01

    In this paper, we present a capacitive sensor digital interface circuit using true capacitance-domain successive approximation that is independent of supply voltage. Robust operation is achieved by using a charge amplifier stage and multiple comparison technique. The interface circuit is insensitive to parasitic capacitances, offset voltages, and charge injection, and is not prone to noise coupling. The proposed design achieves very low temperature sensitivity of 25ppm/oC. A coarse-fine programmable capacitance array allows digitizing a wide capacitance range of 16pF with 12.5-bit quantization limited resolution in a compact area of 0.07mm2. The fabricated prototype is experimentally verified using on-chip sensor and off-chip MEMS capacitive pressure sensor. © 2014 IEEE.

  2. Absolute Position Sensing Based on a Robust Differential Capacitive Sensor with a Grounded Shield Window.

    Science.gov (United States)

    Bai, Yang; Lu, Yunfeng; Hu, Pengcheng; Wang, Gang; Xu, Jinxin; Zeng, Tao; Li, Zhengkun; Zhang, Zhonghua; Tan, Jiubin

    2016-05-11

    A simple differential capacitive sensor is provided in this paper to measure the absolute positions of length measuring systems. By utilizing a shield window inside the differential capacitor, the measurement range and linearity range of the sensor can reach several millimeters. What is more interesting is that this differential capacitive sensor is only sensitive to one translational degree of freedom (DOF) movement, and immune to the vibration along the other two translational DOFs. In the experiment, we used a novel circuit based on an AC capacitance bridge to directly measure the differential capacitance value. The experimental result shows that this differential capacitive sensor has a sensitivity of 2 × 10(-4) pF/μm with 0.08 μm resolution. The measurement range of this differential capacitive sensor is 6 mm, and the linearity error are less than 0.01% over the whole absolute position measurement range.

  3. The Semen pH Affects Sperm Motility and Capacitation.

    Science.gov (United States)

    Zhou, Ji; Chen, Li; Li, Jie; Li, Hongjun; Hong, Zhiwei; Xie, Min; Chen, Shengrong; Yao, Bing

    2015-01-01

    As the chemical environment of semen can have a profound effect on sperm quality, we examined the effect of pH on the motility, viability and capacitation of human sperm. The sperm in this study was collected from healthy males to avoid interference from other factors. The spermatozoa cultured in sperm nutrition solution at pH 5.2, 6.2, 7.2 and 8.2 were analyzed for sperm total motility, progressive motility (PR), hypo-osmotic swelling (HOS) rate, and sperm penetration. Our results showed that these parameters were similar in pH 7.2 and 8.2 sperm nutrition solutions, but decreased in pH 5.2 and 6.2 solutions. The HOS rate exhibited positive correlation with the sperm total motility and PR. In addition, the sperm Na(+)/K(+)-ATPase activity at different pHs was measured, and the enzyme activity was significantly lower in pH 5.2 and 6.2 media, comparing with that in pH 8.2 and pH 7.2 solutions. Using flow cytometry (FCM) and laser confocal scanning microscopy (LCSM) analysis, the intracellular Ca2(+ )concentrations of sperm cultured in sperm capacitation solution at pH 5.2, 6.2, 7.2 and 8.2 were determined. Compared with that at pH 7.2, the mean fluorescence intensity of sperm in pH 5.2 and 6.2 media decreased significantly, while that of pH 8.2 group showed no difference. Our results suggested that the declined Na(+)/K(+)-ATPase activity at acidic pHs result in decreased sperm movement and capacitation, which could be one of the mechanisms of male infertility.

  4. 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.

  5. Synthesis of calcium superoxide

    Science.gov (United States)

    Rewick, R. T.; Blucher, W. G.; Estacio, P. L.

    1972-01-01

    Efforts to prepare Ca(O2) sub 2 from reactions of calcium compounds with 100% O3 and with O(D-1) atoms generated by photolysis of O3 at 2537 A are described. Samples of Ca(OH) sub 2, CaO, CaO2, Ca metal, and mixtures containing suspected impurities to promote reaction have been treated with excess O3 under static and flow conditions in the presence and absence of UV irradiation. Studies with KO2 suggest that the superoxide anion is stable to radiation at 2537 A but reacts with oxygen atoms generated by the photolysis of O3 to form KO3. Calcium superoxide is expected to behave in an analogous.

  6. Capacitive micromachined ultrasonic transducer arrays as tunable acoustic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Lani, Shane W., E-mail: shane.w.lani@gmail.com, E-mail: karim.sabra@me.gatech.edu, E-mail: levent.degertekin@me.gatech.edu; Sabra, Karim G. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); Wasequr Rashid, M.; Hasler, Jennifer [School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States); Levent Degertekin, F. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States)

    2014-02-03

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) operating in immersion support dispersive evanescent waves due to the subwavelength periodic structure of electrostatically actuated membranes in the array. Evanescent wave characteristics also depend on the membrane resonance which is modified by the externally applied bias voltage, offering a mechanism to tune the CMUT array as an acoustic metamaterial. The dispersion and tunability characteristics are examined using a computationally efficient, mutual radiation impedance based approach to model a finite-size array and realistic parameters of variation. The simulations are verified, and tunability is demonstrated by experiments on a linear CMUT array operating in 2-12 MHz range.

  7. Dynamic actuation methods for capacitive MEMS shunt switches

    Science.gov (United States)

    Khater, M. E.; Vummidi, K.; Abdel-Rahman, E. M.; Nayfeh, A. H.; Raman, S.

    2011-03-01

    We develop dynamic actuation methods for capacitive MEMS shunt switches. We show that the dynamic actuation voltage is significantly less than the static actuation voltage and demonstrate 60% reduction in the actuation voltage. We also show that this reduction in the actuation voltage depends on the specific dynamic switching technique adopted. For a given operating condition, the minimum realizable switching time is that obtained using static switching. However, we developed a dynamic switching method that yields comparable switching time to that minimum. We also found that squeeze-film damping is the dominant damping mechanism for a shunt switch with a relatively slender bridge (aspect ratio of 11:1).

  8. Low-Frequency Relaxation Oscillations in Capacitive Discharge Processes

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhu-Wen; M.A.LIEBERMAN; Sungjin KIM; JI Shi-Yin; DENG Ming-Sen; SUN Guang-Yu

    2008-01-01

    Low-frequency (2.72-3.70 Hz) relaxation oscillations at 100m Tort at higher absorbed power were observed from time-varying optical emission of the main discharge chamber and the periphery.We interpret the low frequency oscillations using an electromagnetic model of the slot impedance with parallel connection variational peripheral capacitance,coupled to a circuit analysis of the system including the matching network.The model results are in general agreement with the experimental observations,and indicate a variety of bchaviours dependent on the matching conditions.

  9. Leakage Currents and Capacitances of Thick CZT Detectors

    OpenAIRE

    Garson III, Alfred; Li, Qiang; Jung, Ira V.; Dowkontt, Paul; Bose, Richard; Simburger, Garry; Krawczynski, Henric

    2009-01-01

    The quality of Cadmium Zinc Telluride (CZT) detectors is steadily improving. For state of the art detectors, readout noise is thus becoming an increasingly important factor for the overall energy resolution. In this contribution, we present measurements and calculations of the dark currents and capacitances of 0.5 cm-thick CZT detectors contacted with a monolithic cathode and 8x8 anode pixels on a surface of 2 cm x 2 cm. Using the NCI ASIC from Brookhaven National Laboratory as an example, we...

  10. Rapid Prototyping of Tangibles with a Capacitive Mouse

    DEFF Research Database (Denmark)

    Ramos, Juan David Hincapie; Esbensen, Morten; Kogutowska, Magdalena

    2011-01-01

    This paper presents the Toki toolkit: a do-it-yourself guide and API to support the rapid prototyping of tangibles. The toolkit provides support for two common requirements for tangibles: capture of touch input by an user and commu- nication of such input to a computer. At the core of the toolkit...... 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...

  11. Correlated Coulomb drag in capacitively coupled quantum-dot structures

    DEFF Research Database (Denmark)

    Kaasbjerg, Kristen; Jauho, Antti-Pekka

    2016-01-01

    We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs) -- a biasdriven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach which accounts for higher-order tunneling (cotunneling....... Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments...

  12. Experimental Analysis of Bisbenzocyclobutene Bonded Capacitive Micromachined Ultrasonic Transducers

    OpenAIRE

    2016-01-01

    Experimental measurement results of a 1.75 mm × 1.75 mm footprint area Capacitive Micromachined Ultrasonic Transducer (CMUT) planar array fabricated using a bisbenzocyclobutene (BCB)-based adhesive wafer bonding technique has been presented. The array consists of 40 × 40 square diaphragm CMUT cells with a cavity thickness of 900 nm and supported by 10 µm wide dielectric spacers patterned on a thin layer of BCB. A 150 µm wide one µm thick gold strip has been used as the contact pad for gold wi...

  13. New Multipole Method for 3-D Capacitance Extraction

    Institute of Scientific and Technical Information of China (English)

    Zhao-Zhi Yang; Ze-Yi Wang

    2004-01-01

    This paper describes an effcient improvement of the multipole accelerated boundary element method for 3-D capacitance extraction.The overall relations between the positions of 2-D boundary elements are considered instead of only the relations between the center-points of the elements,and a new method of cube partitioning is introduced.Numerical results are presented to demonstrate that the method is accurate and has nearly linear computational growth as O(n),where n is the number of panels/boundary elements.The proposed method is more accurate and much faster than Fastcap.

  14. Design of capacitance sensor system for void fraction measurement

    Institute of Scientific and Technical Information of China (English)

    LIU Yi-ping; NIU Gang; WANG Jing

    2005-01-01

    Simulation and optimization were applied to a capacitive sensor system based on electrical tomography technology.Sensors, consisting of Morgantown Energy Technology Center (METC) axial synchro driving guard electrodes and two sets of detecting electrodes, make it possible to obtain simultaneously two groups of signals of the void fraction in oil-gas two-phase flow.The computational and experimental results showed that available sensors, charactered by high resolution and fast real-time response can be used for real-time liquid-gas two-phase flow pattern determination.

  15. Contrast distortion induced by modulation voltage in scanning capacitance microscopy

    Science.gov (United States)

    Chang, M. N.; Hu, C. W.; Chou, T. H.; Lee, Y. J.

    2012-08-01

    With a dark-mode scanning capacitance microscopy (SCM), we directly observed the influence of SCM modulation voltage (MV) on image contrasts. For electrical junctions, an extensive modulated area induced by MV may lead to noticeable changes in the SCM signal phase and intensity, resulting in a narrowed junction image and a broadened carrier concentration profile. This contrast distortion in SCM images may occur even if the peak-to-peak MV is down to 0.3 V. In addition, MV may shift the measured electrical junction depth. The balance of SCM signals components explain these MV-induced contrast distortions.

  16. FPGA Based Low Power ROM Design Using Capacitance Scaling

    DEFF Research Database (Denmark)

    Bansal, Meenakshi; Bansal, Neha; Saini, Rishita

    2015-01-01

    An ideal capacitor will not dissipate any power, but a real capacitor wil l have some power dissipation. In this work, we are going to design capacitance scaling based low power ROM design. In order to test the compatibility of this ROM design with latest i7 Processor, we are operating this ROM w...... in I/O Power, saving of 0.2% occur in Leakage Power, there will be a saving of 11.54% occur in Total Power. This design is implemented on Virtex-5 FPGA using Xilinx ISE and Verilog....

  17. Capacitively Loaded Loop-Based Antennas with Reconfigurable Radiation Patterns

    Directory of Open Access Journals (Sweden)

    Saber Dakhli

    2015-01-01

    Full Text Available A class of metamaterial-inspired antennas having reconfigurable radiation patterns is proposed. They consist of a driven monopole antenna with one- and two-capacitively loaded loop (CLL, near field resonant parasitic elements. Two configurations are studied by considering the state of these CLL elements as being either open or closed configurations. Simulation results explain the design features and demonstrate that the structure can change its beam direction simply by controlling the switched states. Two prototypes with one- and two-CLL elements were fabricated and tested. The measured impedance mismatch and radiation pattern results are presented and compared to the corresponding simulated values.

  18. 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...

  19. Time dependent capacitance voltage measurements on Cu(In,Ga)Se{sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Adler, Tobias; Klein, Andreas [Darmstadt University of Technology, Institute of Materials Science, Petersenstrasse 32, D-64287 Darmstadt (Germany); Witte, Wolfram; Hariskos, Dimitrios [Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung Baden-Wuerttemberg (ZSW), Industriestrasse 6, D-70565 Stuttgart (Germany)

    2011-07-01

    Capacitance Voltage (C-V) measurements are widely used to determine the doping density of semiconductor interfaces in dependence on the width of the space charge layer. In Cu(In,Ga)Se{sub 2} (CIGS) solar cells we observe a time dependent capacitance signal, which can be explained by different models like filling and emptying of electronic (metastable) defect states or by the diffusion of copper ions. The observed capacitance transients are compared to the different models.

  20. Analytical comparison of circular diaphragm based simple, single and double touch mode - MEMS capacitive pressure sensor

    Science.gov (United States)

    Jindal, Sumit Kumar; Raghuwanshi, Sanjeev Kumar

    2016-03-01

    In this paper a comparative study is done between normal capacitive pressure sensor, a touch mode capacitive pressure sensor and a double touch mode capacitive pressure sensor. The diaphragm in use is of circular shape. The theory and underlying equations has been described for the said devices and then simulations have been done for different performance parameters to understand the advantage of one over the other.

  1. Internet portals as portfolios of entry options

    NARCIS (Netherlands)

    Perotti, E.C.; Rossetto, S.

    2000-01-01

    We investigate the valuation of platform investment, such as a software operating system or an Internet portal WebPage. Platform investment is the creation of an innovative distribution and production infrastructure, which increases access to customers; as a result it reduces entry costs in related

  2. Processes with multiple entries and exits

    NARCIS (Netherlands)

    Bergstra, J.A.; Stefanescu, G.

    1995-01-01

    This paper is an attempt to integrate the algebra of communicating processes (ACP) and the algebra of flownomials (AF). Basically, this means to combine axiomatized parallel and looping operators. To this end we introduce a model of process graphs with multiple entries and exits. In this model the u

  3. Entry modes of European firms in Vietnam

    Directory of Open Access Journals (Sweden)

    Daniel Simonet

    2012-09-01

    Full Text Available Purpose: The purpose of the paper is to explore the entry modes of EU firms setting up operations in Vietnam. Design/methodology/approach: we use a case study approach on Haymarket, Cadbury, Creative Education, Fairchild, Aventis and Artemisinin and Farming International using interviews from managerial professionals in Vietnam. Findings: Despite the fact that Vietnam has been opening up for more than 20 years, licensing is the preferred entry mode because of the risks involved in venturing with local firms; that preference signals a low level commitment and a high perception of risk and state interference. In line with Vietnam transition to state - rather than private market - capitalism, a foreign company opting for a joint-venture will do so with a state-owned rather than privately-owned company. The choice of a subsidiary can be explained by the lack of trust in partners and institutions, not by improvement in the socio-political environment. Limitations: In determining the entry mode strategy, the paper focuses on the Uppsala school’s “psychic distance” (e.g. cultural distance, lack of trust rather than on firm-specific advantages (Rugman, 1980; 2006. Key-words: international entry mode; emerging markets; subsidiary; joint-venture; India; Vietnam

  4. Flavivirus cell entry and membrane fusion

    NARCIS (Netherlands)

    Smit, Jolanda M.; Moesker, Bastiaan; Rodenhuis-Zybert, Izabela; Wilschut, Jan

    2011-01-01

    Flaviviruses, such as dengue virus and West Nile virus, are enveloped viruses that infect cells through receptor-mediated endocytosis and fusion from within acidic endosomes. The cell entry process of flaviviruses is mediated by the viral E glycoprotein. This short review will address recent advance

  5. HIV-1 Entry Inhbitors: An Overview

    Science.gov (United States)

    Kuritzkes, Daniel R.

    2009-01-01

    Purpose of review This review provides an overview of HIV-1 entry inhibitors, with a focus on chemokine receptor antagonists. Recent findings Entry of HIV-1 into target cells is an ordered multi-step process involving attachment, co-receptor binding and fusion. Inhibitors of each step have been identified and shown to have antiviral activity in clinical trials. Phase 1-2 trials of monoclonal antibodies and small-molecule attachment inhibitors have demonstrated activity in HIV-1-infected subjects, but none has progressed to later phase clinical trials. The post-attachment inhibitor ibalizumab has shown activity in phase 1 and 2 trials; further studies are anticipated. The CCR5 antagonists maraviroc (now been approved for clinical use) and vicriviroc (in phase 3 trials) have shown significant benefit in controlled trials in treatment-experienced subjects; additional CCR5 antagonists are in various stages of clinical development. Targeting CXCR4 has proven to be more challenging. Although proof of concept has been demonstrated in phase 1-2 trials of two compounds, neither proved suitable for chronic administration. Little progress has been reported in developing longer acting or orally bioavailable fusion inhibitors. Summary ACCR5 antagonist and a fusion inhibitor are approved for use as HIV-1 entry inhibitors. Development of drugs targeting other steps in HIV-1 entry is ongoing. PMID:19339945

  6. 19 CFR 4.8 - Preliminary entry.

    Science.gov (United States)

    2010-04-01

    ... electronic equivalent of a complete Customs Form 1302 (Cargo Declaration), in the manner provided in § 4.7(b... 19 Customs Duties 1 2010-04-01 2010-04-01 false Preliminary entry. 4.8 Section 4.8 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE...

  7. Continuous Aerodynamic Modelling of Entry Shapes

    NARCIS (Netherlands)

    Dirkx, D.; Mooij, E.

    2011-01-01

    During the conceptual design phase of a re-entry vehicle, the vehicle shape can be varied and its impact on performance evaluated. To this end, the continuous modeling of the aerodynamic characteristics as a function of the shape is useful in exploring the full design space. Local inclination method

  8. Bovine serum albumin detection and quantitation based on capacitance measurements of liquid crystals

    Science.gov (United States)

    Lin, Chi-Hao; Lee, Mon-Juan; Lee, Wei

    2016-08-01

    Liquid crystal (LC)-based biosensing is generally limited by the lack of accurate quantitative strategies. This study exploits the unique electric capacitance properties of LCs to establish quantitative assay methods for bovine serum albumin (BSA) biomolecules. By measuring the voltage-dependent electric capacitance of LCs under an alternating-current field with increasing amplitude, positive correlations were derived between the BSA concentration and the electric capacitance parameters of LCs. This study demonstrates that quantitative analysis can be achieved in LC-based biosensing through electric capacitance measurements extensively employed in LCD research and development.

  9. Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia

    Science.gov (United States)

    Wilson, Rosamund J; Copley, J Brian

    2017-01-01

    Background Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. Scope A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent-to-treat population (N=2520), 752 patients with recorded dose data for calcium acetate (n=551)/calcium carbonate (n=201) at baseline and lanthanum carbonate at week 16 were studied. Elemental calcium intake, serum phosphate, corrected serum calcium, and serum intact parathyroid hormone levels were analyzed. Findings Of the 551 patients with calcium acetate dose data, 271 (49.2%) had an elemental calcium intake of at least 1.5 g/day at baseline, and 142 (25.8%) had an intake of at least 2.0 g/day. Mean (95% confidence interval [CI]) serum phosphate levels were 6.1 (5.89, 6.21) mg/dL at baseline and 6.2 (6.04, 6.38) mg/dL at 16 weeks; mean (95% CI) corrected serum calcium levels were 9.3 (9.16, 9.44) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Of the 201 patients with calcium carbonate dose data, 117 (58.2%) had an elemental calcium intake of at least 1.5 g/day, and 76 (37.8%) had an intake of at least 2.0 g/day. Mean (95% CI) serum phosphate levels were 5.8 (5.52, 6.06) mg/dL at baseline and 5.8 (5.53, 6.05) mg/dL at week 16; mean (95% CI) corrected serum calcium levels were 9.7 (9.15, 10.25) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Conclusion Calcium acetate/calcium carbonate phosphate binders, taken to control serum phosphate levels, may result in high levels of elemental calcium intake. This may lead to complications related to calcium balance. PMID:28182142

  10. Flexible Bond Wire Capacitive Strain Sensor for Vehicle Tyres

    Directory of Open Access Journals (Sweden)

    Siyang Cao

    2016-06-01

    Full Text Available The safety of the driving experience and manoeuvrability of a vehicle can be improved by detecting the strain in tyres. To measure strain accurately in rubber, the strain sensor needs to be flexible so that it does not deform the medium that it is measuring. In this work, a novel flexible bond wire capacitive strain sensor for measuring the strain in tyres is developed, fabricated and calibrated. An array of 25 micron diameter wire bonds in an approximately 8 mm × 8 mm area is built to create an interdigitated structure, which consists of 50 wire loops resulting in 49 capacitor pairs in parallel. Laser machining was used to pattern copper on a flexible printed circuit board PCB to make the bond pads for the wire attachment. The wire array was finally packaged and embedded in polydimethylsiloxane (PDMS, which acts as the structural material that is strained. The capacitance of the device is in a linear like relationship with respect to the strain, which can measure the strain up to at least ±60,000 micro-strain (±6% with a resolution of ~132 micro-strain (0.013%. In-tyre testing under static loading has shown the ability of the sensor to measure large tyre strains. The technology used for sensor fabrication lends itself to mass production and so the design is considered to be consistent with low cost commercialisable strain sensing technology.

  11. Opening of K+ channels by capacitive stimulation from silicon chip

    Science.gov (United States)

    Ulbrich, M. H.; Fromherz, P.

    2005-10-01

    The development of stable neuroelectronic systems requires a stimulation of nerve cells from semiconductor devices without electrochemical effects at the electrolyte/solid interface and without damage of the cell membrane. The interaction must rely on a reversible opening of voltage-gated ion channels by capacitive coupling. In a proof-of-principle experiment, we demonstrate that Kv1.3 potassium channels expressed in HEK293 cells can be opened from an electrolyte/oxide/silicon (EOS) capacitor. A sufficient strength of electrical coupling is achieved by insulating silicon with a thin film of TiO2 to achieve a high capacitance and by removing NaCl from the electrolyte to enhance the resistance of the cell-chip contact. When a decaying voltage ramp is applied to the EOS capacitor, an outward current through the attached cell membrane is observed that is specific for Kv1.3 channels. An open probability up to fifty percent is estimated by comparison with a numerical simulation of the cell-chip contact.

  12. Capacitated arc routing problem and its extensions in waste collection

    Energy Technology Data Exchange (ETDEWEB)

    Fadzli, Mohammad; Najwa, Nurul [Institut Matematik Kejuruteraan, Universiti Malaysia Perlis, Kampus Pauh Putra, 02600 Arau, Perlis (Malaysia); Luis, Martino [Othman Yeop Abdullah Graduate School of Business, Universiti Utara Malaysia, 06010 Sintok, Kedah (Malaysia)

    2015-05-15

    Capacitated arc routing problem (CARP) is the youngest generation of graph theory that focuses on solving the edge/arc routing for optimality. Since many years, operational research devoted to CARP counterpart, known as vehicle routing problem (VRP), which does not fit to several real cases such like waste collection problem and road maintenance. In this paper, we highlighted several extensions of capacitated arc routing problem (CARP) that represents the real-life problem of vehicle operation in waste collection. By purpose, CARP is designed to find a set of routes for vehicles that satisfies all pre-setting constraints in such that all vehicles must start and end at a depot, service a set of demands on edges (or arcs) exactly once without exceeding the capacity, thus the total fleet cost is minimized. We also addressed the differentiation between CARP and VRP in waste collection. Several issues have been discussed including stochastic demands and time window problems in order to show the complexity and importance of CARP in the related industry. A mathematical model of CARP and its new version is presented by considering several factors such like delivery cost, lateness penalty and delivery time.

  13. A novel capacitance sensor for fireside corrosion measurement

    Science.gov (United States)

    Ban, Heng; Li, Zuoping

    2009-11-01

    Fireside corrosion in coal-fired power plants is a leading mechanism for boiler tube failures. Online monitoring of fireside corrosion can provide timely data to plant operators for mitigation implementation. This paper presents a novel sensor concept for measuring metal loss based on electrical capacitance. Laboratory-scale experiments demonstrated the feasibility of design, fabrication, and operation of the sensor. The fabrication of the prototype sensor involved sputtering deposition of a thin metal coating with varying thickness on a ceramic substrate. Corrosion metal loss resulted in a proportional decrease in electrical capacitance of the sensor. Laboratory experiments using a muffle furnace with an oxidation environment demonstrated that low carbon steel coatings on ceramic substrate survived cyclic temperatures over 500 °C. Measured corrosion rates of sputtered coating in air had an Arrhenius exponential dependence on temperature, with metal thickness loss ranging from 2.0 nm/h at 200 °C to 2.0 μm/h at 400 °C. Uncertainty analysis indicated that the overall measurement uncertainty was within 4%. The experimental system showed high signal-to-noise ratio, and the sensor could measure submicrometer metal thickness changes. The laboratory experiments demonstrated that the sensor concept and measurement system are capable of short term, online monitoring of metal loss, indicating the potential for the sensor to be used for fireside corrosion monitoring and other metal loss measurement.

  14. Evidence for nonlinear capacitance in biomembrane channel system.

    Science.gov (United States)

    Ghosh, S; Bera, A K; Das, S

    1999-10-01

    The electrophysiological properties of voltage-dependent anion channels from mitochondrial membrane have been studied in a bilayer membrane system. It was observed that the probability of opening of the membrane channel depends on externally applied voltage and the plot is a bell-shaped curve symmetric around probability axis. A scheme of conformational energy levels under varying externally applied voltage was formulated. Assuming that the probability follows Boltzmann distribution, we arrive at an expression of change in energy containing a separate term identical to the energy of a capacitor. This fact indicates the possibility of existence of an added capacitance due to the channel protein. Further it was shown that the aforesaid channel capacitor could be a function of voltage leading to nonlinearity. We have offered a general method of calculating nonlinear capacitance from the experimental data on opening probability of a membrane channel. In case of voltage-dependent anion channel the voltage dependence of the capacitor has a power 0.786. The results have been interpreted in view of the structural organization of the channel protein in the membrane. Our hypothesis is that the phenomenon of capacitor behaviour is a general one for membrane channels.

  15. Capacitated arc routing problem and its extensions in waste collection

    Science.gov (United States)

    Fadzli, Mohammad; Najwa, Nurul; Luis, Martino

    2015-05-01

    Capacitated arc routing problem (CARP) is the youngest generation of graph theory that focuses on solving the edge/arc routing for optimality. Since many years, operational research devoted to CARP counterpart, known as vehicle routing problem (VRP), which does not fit to several real cases such like waste collection problem and road maintenance. In this paper, we highlighted several extensions of capacitated arc routing problem (CARP) that represents the real-life problem of vehicle operation in waste collection. By purpose, CARP is designed to find a set of routes for vehicles that satisfies all pre-setting constraints in such that all vehicles must start and end at a depot, service a set of demands on edges (or arcs) exactly once without exceeding the capacity, thus the total fleet cost is minimized. We also addressed the differentiation between CARP and VRP in waste collection. Several issues have been discussed including stochastic demands and time window problems in order to show the complexity and importance of CARP in the related industry. A mathematical model of CARP and its new version is presented by considering several factors such like delivery cost, lateness penalty and delivery time.

  16. High capacitance of coarse-grained carbide derived carbon electrodes

    Science.gov (United States)

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; Zozulya, Yuliya; Simon, Patrice; Gogotsi, Yury

    2016-02-01

    We report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. Using a titanium carbide (TiC) precursor, we synthesized 70-250 μm sized particles with high surface area and a narrow pore size distribution. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. The material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250-1000 micron thick dense CDC films with up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.

  17. Effect of displacement on resistance and capacitance of polyaniline film

    Institute of Scientific and Technical Information of China (English)

    Khasan Sanginovich Karimov; Muhammad Tariq Saeed; Fazal Ahmad Khalid; Syed Abdul Moiz

    2011-01-01

    This paper investigates the properties of displacement sensors based on polyaniline(PANI)films. About 1 wt% of PANI micropowder is mixed and stirred in a solution of 90 wt% water and 10 wt% alcohol at room temperature. The films of PANI are deposited from solution by drop-casting on Ag electrodes, which are preliminary deposited on glass substrates. The thicknesses of the PANI films are in the range of 20 jun-80 p.m. A displacement sensor with polyaniline film as an active material is designed and fabricated. The investigations showed that, on average, the AC resistance of the sensor decreases by 2 times and the capacitance accordingly increases by 1.6 times as the displacement changes in the range of 0 mm-0.5 mm. The polyaniline is the only active material of the displacement sensor. The resistance and capacitance of the PANI changes under the pressure of spring and elastic rubber, and this pressure is created by the downward movement of the micrometer.

  18. 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.

  19. [Raynaud's phenomenon and calcium blocking agents. A preliminary open study with flunarizine].

    Science.gov (United States)

    Centonze, V; Campanale, G; Vino, M; Caporaletti, P; Magrone, D; Russo, P; Di Bari, M; Loragno, V; Albano, O

    1991-04-30

    Raynaud's phenomenon (Raynaud's disease), an accessual vascular acrosyndrome characterised by an important constriction of distal arterioles, has still no specific pharmacological therapy. In the last years, the use of calcium-entry-blockers (nifedipine, diltiazem, verapamil, nicardipine), drugs able to control the contractility of the vessels, showed some positive results. Considering this data, we appraised the efficacy of flunarizine, another calcium-entry-blocker, in a preliminary study of 28 patients (23 females, 5 males, aged between 15 and 48 years) suffering from Raynaud's disease. Apart from a statistically insignificant improvement of subjective symptoms (i.e. acroparesthesias, cold extremities) flunarizine (10 mg/day for 1 month) did not have positive results. Finally, this drug caused some side-effects: drowsiness, increase of weight and appetite, but without a real necessity for withdrawal of therapy.

  20. Electrical Capacitance Volume Tomography with High-Contrast Dielectrics

    Science.gov (United States)

    Nurge, Mark

    2010-01-01

    The Electrical Capacitance Volume Tomography (ECVT) system has been designed to complement the tools created to sense the presence of water in nonconductive spacecraft materials, by helping to not only find the approximate location of moisture but also its quantity and depth. The ECVT system has been created for use with a new image reconstruction algorithm capable of imaging high-contrast dielectric distributions. Rather than relying solely on mutual capacitance readings as is done in traditional electrical capacitance tomography applications, this method reconstructs high-resolution images using only the self-capacitance measurements. The image reconstruction method assumes that the material under inspection consists of a binary dielectric distribution, with either a high relative dielectric value representing the water or a low dielectric value for the background material. By constraining the unknown dielectric material to one of two values, the inverse math problem that must be solved to generate the image is no longer ill-determined. The image resolution becomes limited only by the accuracy and resolution of the measurement circuitry. Images were reconstructed using this method with both synthetic and real data acquired using an aluminum structure inserted at different positions within the sensing region. The cuboid geometry of the system has two parallel planes of 16 conductors arranged in a 4 4 pattern. The electrode geometry consists of parallel planes of copper conductors, connected through custom-built switch electronics, to a commercially available capacitance to digital converter. The figure shows two 4 4 arrays of electrodes milled from square sections of copper-clad circuit-board material and mounted on two pieces of glass-filled plastic backing, which were cut to approximately square shapes, 10 cm on a side. Each electrode is placed on 2.0-cm centers. The parallel arrays were mounted with the electrode arrays approximately 3 cm apart. The open ends

  1. 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.

  2. STIM and calcium channel complexes in cancer.

    Science.gov (United States)

    Jardin, Isaac; Rosado, Juan A

    2016-06-01

    The ion Ca(2+) is a ubiquitous second messenger that mediates a variety of cellular functions. Dysfunction of the mechanisms involved in Ca(2+) homeostasis underlies a number of pathological processes, including cancer. Store-operated Ca(2+) entry (SOCE) is a major mechanism for Ca(2+) entry modulated by the intracellular Ca(2+) stores. The Ca(2+)-selective store-operated current (ICRAC) is mediated by the endoplasmic reticulum (ER) Ca(2+) sensor STIM1 and the store-operated Ca(2+) (SOC) channel Orai1, while other non-selective cation currents (ISOC) involves the participation of members of the canonical transient receptor potential (TRPC) channel family, including TRPC1. Distinct isoforms of the key components of SOCE have been described in mammalian cells, STIM1 and 2, Orai1-3 and TRPC1-7. In cancer cells, SOCE has been reported to play an important role in cell cycle progression and proliferation, migration, metastasis and evasion of apoptosis. Changes in the expression of the key elements of SOCE and Ca(2+) homeostasis remodeling have been account to play important roles in the phenotypic changes observed in transformed cells. Despite there are differences in the expression level of the molecular components of SOCE, as well as in the relevance of the STIM, Orai and TRPC isoforms in SOCE and tumorigenesis among cancer cell types, there is a body of evidence supporting an important role for SOCE underlying the phenotypic modifications of cancer cells that propose STIM and the SOC channels as suitable candidate targets for future prognostic or therapeutic strategies. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen.

  3. Designing dynamical output feedback controllers for store-operated Ca²+ entry.

    Science.gov (United States)

    Liu, Weijiu; Tang, Fusheng; Chen, Jingvoon

    2010-11-01

    Store-operated calcium entry (SOCE) has been proposed as the main process controlling Ca²+ entry in non-excitable cells. Although recent breakthroughs in experimental studies of SOCE have been made, its mathematical modeling has not been developed. In the present work, SOCE is viewed as a feedback control system subject to an extracellular agonist disturbance and an extracellular calcium input. We then design a dynamic output feedback controller to reject the disturbance and track Ca²+ resting levels in the cytosol and the endoplasmic reticulum (ER). The constructed feedback control system is validated by published experimental data and its global asymptotic stability is proved by using the LaSalle's invariance principle. We then simulate the dynamic responses of STIM1 and Orai1, two major components in the operation of the store-operated channels, to the depletion of Ca²+ in the ER with thapsigargin, which show that: (1) Upon the depletion of Ca²+ in the ER, the concentrations of activated STIM1 and STIM1-Orai1 cluster are elevated gradually, indicating that STIM1 is accumulating in the ER-PM junctions and that the cytosolic portion of the active STIM1 is binding to Orai1 and driving the opening of CRAC channels for Ca²+ entry; (2) after the extracellular Ca²+ addition, the concentrations of both STIM1 and STIM1-Orai1 cluster decrease but still much higher than the original levels. We also simulate the system responses to the agonist disturbance, which show that, when a sequence of periodic agonist pulses is applied, the system returns to its equilibrium after each pulse. This indicates that the designed feedback controller can reject the disturbance and track the equilibrium.

  4. Analytic Guidance for the First Entry in a Skip Atmospheric Entry

    Science.gov (United States)

    Garcia-Llama, Eduardo

    2007-01-01

    This paper presents an analytic method to generate a reference drag trajectory for the first entry portion of a skip atmospheric entry. The drag reference, expressed as a polynomial function of the velocity, will meet the conditions necessary to fit the requirements of the complete entry phase. The generic method proposed to generate the drag reference profile is further simplified by thinking of the drag and the velocity as density and cumulative distribution functions respectively. With this notion it will be shown that the reference drag profile can be obtained by solving a linear algebraic system of equations. The resulting drag profile is flown using the feedback linearization method of differential geometric control as guidance law with the error dynamics of a second order homogeneous equation in the form of a damped oscillator. This approach was first proposed as a revisited version of the Space Shuttle Orbiter entry guidance. However, this paper will show that it can be used to fly the first entry in a skip entry trajectory. In doing so, the gains in the error dynamics will be changed at a certain point along the trajectory to improve the tracking performance.

  5. Design and Simulation Tools for Planetary Atmospheric Entry Vehicles Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Atmospheric entry is one of the most critical phases of flight during planetary exploration missions. During the design of an entry vehicle, experimental and...

  6. Adaptive Deployable Entry and Placement Technology (ADEPT) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The ADEPT Project is developing a mechanically deployable low-ballistic coefficient aeroshell entry system to perform entry descent landing (EDL) functions for...

  7. 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.

  8. 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.

  9. 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......

  10. 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...

  11. 31 CFR 337.6 - Conversions to book-entry.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Conversions to book-entry. 337.6... HOUSING ADMINISTRATION DEBENTURES Certificated Debentures § 337.6 Conversions to book-entry. Upon implementation of the book-entry debenture system, to be announced in advance by separate public notice, all...

  12. 14 CFR 375.24 - Entry and clearance.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Entry and clearance. 375.24 Section 375.24 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) SPECIAL... Entry and clearance. All U.S. entry and clearance requirements for aircraft, passengers, crews,...

  13. Maximum Atmospheric Entry Angle for Specified Retrofire Impulse

    Directory of Open Access Journals (Sweden)

    T. N. Srivastava

    1969-07-01

    Full Text Available Maximum atmospheric entry angles for vehicles initially moving in elliptic orbits are investigated and it is shown that tangential retrofire impulse at the apogee results in the maximum entry angle. Equivalence of maximizing the entry angle and minimizing the retrofire impulse is also established.

  14. 19 CFR 143.16 - Substitution of warehouse entry.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Substitution of warehouse entry. 143.16 Section 143.16 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT... warehouse entry. The importer may substitute an entry for warehouse at any time within 1 year from the...

  15. 30 CFR 877.14 - Entry for emergency reclamation.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Entry for emergency reclamation. 877.14 Section 877.14 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR ABANDONED MINE LAND RECLAMATION RIGHTS OF ENTRY § 877.14 Entry for emergency reclamation. (a)...

  16. 50 CFR 91.16 - Submission procedures for entry.

    Science.gov (United States)

    2010-10-01

    ... (CONTINUED) MISCELLANEOUS PROVISIONS MIGRATORY BIRD HUNTING AND CONSERVATION STAMP CONTEST Procedures for.... Each entry must be accompanied by a non-refundable entrance fee and a completed and signed Reproduction... the Reproduction Rights Agreement must be attached to the back of the entry. (b) Each entry should...

  17. 40 CFR 90.1207 - Entry and access.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Entry and access. 90.1207 Section 90... § 90.1207 Entry and access. (a) To allow the Administrator to determine whether a manufacturer is... maintenance. (c) The provisions of § 90.705(c), (d), (e), (f) and (g) also apply to entry and access...

  18. 77 FR 17492 - Expansion of Global Entry to Additional Airports

    Science.gov (United States)

    2012-03-26

    ... selection process, and the initial airport locations. See 77 FR 5681 and 8 CFR 235.12. Travelers who wish to... SECURITY U.S. Customs and Border Protection Expansion of Global Entry to Additional Airports AGENCY: U.S... as Global Entry, at twenty major U.S. airports. Global Entry allows pre-approved,...

  19. 19 CFR 143.35 - Procedure for electronic entry summary.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Procedure for electronic entry summary. 143.35 Section 143.35 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) SPECIAL ENTRY PROCEDURES Electronic Entry Filing § 143.35...

  20. Extracellular calcium sensing and extracellular calcium signaling

    Science.gov (United States)

    Brown, E. M.; MacLeod, R. J.; O'Malley, B. W. (Principal Investigator)

    2001-01-01

    , localized changes in Ca(o)(2+) within the ECF can originate from several mechanisms, including fluxes of calcium ions into or out of cellular or extracellular stores or across epithelium that absorb or secrete Ca(2+). In any event, the CaR and other receptors/sensors for Ca(o)(2+) and probably for other extracellular ions represent versatile regulators of numerous cellular functions and may serve as important therapeutic targets.

  1. Involvement of phospholipase D in store-operated calcium influx in vascular smooth muscle cells.

    Science.gov (United States)

    Walter, M; Tepel, M; Nofer, J R; Neusser, M; Assmann, G; Zidek, W

    2000-08-11

    In non-excitable cells, sustained intracellular Ca2+ increase critically depends on influx of extracellular Ca2+. Such Ca2+ influx is thought to occur by a 'store-operated' mechanism, i.e. the signal for Ca2+ entry is believed to result from the initial release of Ca2+ from inositol 1,4,5-trisphosphate-sensitive intracellular stores. Here we show that the depletion of cellular Ca2+ stores by thapsigargin or bradykinin is functionally linked to a phosphoinositide-specific phospholipase D (PLD) activity in cultured vascular smooth muscle cells (VSMC), and that phosphatidic acid formed via PLD enhances sustained calcium entry in this cell type. These results suggest a regulatory role for PLD in store-operated Ca2+ entry in VSMC.

  2. Novel graphene-like electrodes for capacitive deionization.

    Science.gov (United States)

    Li, Haibo; Zou, Linda; Pan, Likun; Sun, Zhuo

    2010-11-15

    Capacitive deionization (CDI) is a novel technology that has been developed for removal of charged ionic species from salty water, such as salt ions. The basic concept of CDI, as well as electrosorption, is to force charged ions toward oppositely polarized electrodes through imposing a direct electric field to form a strong electrical double layer and hold the ions. Once the electric field disappears, the ions are instantly released back to the bulk solution. CDI is an alternative low-energy consumption desalination technology. Graphene-like nanoflakes (GNFs) with relatively high specific surface area have been prepared and used as electrodes for capacitive deionization. The GNFs were synthesized by a modified Hummers' method using hydrazine for reduction. They were characterized by atomic force microscopy, N2 adsorption at 77 K and electrochemical workstation. It was found that the ratio of nitric acid and sulfuric acid plays a vital role in determining the specific surface area of GNFs. Its electrosorption performance was much better than commercial activated carbon (AC), suggesting a great potential in capacitive deionisation application. Further, the electrosorptive performance of GNFs electrodes with different bias potentials, flow rates and ionic strengths were measured and the electrosorption isotherm and kinetics were investigated. The results showed that GNFs prepared by this process had the specific surface area of 222.01 m²/g. The specific electrosorptive capacity of the GNFs was 23.18 µmol/g for sodium ions (Na+) when the initial concentration was at 25 mg/L, which was higher than that of previously reported data using graphene and AC under the same experimental condition. In addition, the equilibrium electrosorption capacity was determined as 73.47 µmol/g at 2.0 V by fitting data through the Langmuir isotherm, and the rate constant was found to be 1.01 min⁻¹ by fitting data through pseudo first-order adsorption. The results suggested that the

  3. CAPACITIVE TOMOGRAPHY FOR THE LOCATION OF PLASTIC PIPE

    Energy Technology Data Exchange (ETDEWEB)

    Brian J. Huber

    2002-10-30

    Throughout the utility industry, there is high interest in subsurface imaging of plastic, ceramic, and metallic objects because of the cost, reliability, and safety benefits available in avoiding impacts with the existing infrastructure and in reducing inappropriate excavations. Industry interest in locating plastic pipe has resulted in funding available for the development of technologies that enable this imaging. Gas Technology Institute (GTI) proposes to develop a compact and inexpensive capacitive tomography imaging sensor that takes the form of a flat plate or flexible mat that can be placed on the ground to image objects embedded in the soil. A compact, low-cost sensor that can image objects through soil could be applied to multiple operations and will produce a number of cost savings for the gas industry. In a stand-alone mode, it could be used to survey an area prior to excavation. The technology would improve the accuracy and reliability of any operation that involves excavation by locating or avoiding buried objects. An accurate subsurface image of an area will enable less costly keyhole excavations and other cost-saving techniques. Ground penetrating radar (GPR) has been applied to this area with limited success. Radar requires a high-frequency carrier to be injected into the soil: the higher the frequency, the greater the image resolution. Unfortunately, high-frequency radio waves are more readily absorbed by soil. Also, high-frequency operation raises the cost of the associated electronics. By contrast, the capacitive tomography sensor uses low frequencies with a multiple-element antenna to obtain good resolution. Low-frequency operation lowers the cost of the associated electronics while improving depth of penetration. The objective of this project is to combine several existing techniques in the area of capacitive sensing to quickly produce a demonstrable prototype. The sensor itself will take the form of a flat array of electrodes that can be

  4. Prototipicality in entries of school dictionaries

    Directory of Open Access Journals (Sweden)

    Everton Castro de Almeida

    2015-01-01

    Full Text Available Theoretical Lexicography is the discipline which, in a general way, studies and criticizes the dictionaries. It is open to the theoretical contribution from other fields of research, such as Text Linguistics, Pragmatics, and Multimodality, once they may show another lexical dimension. Thus, we base our analysis on the theoretical support from Prototypes Theory, from cognitive sciences. In that sense, this paper aims to identify and describe the prototypicality in entries from the five type 3 dictionaries from the PNLD 2012 (National Plan for the Didactic Books. In order to do so, we use theories from Pontes (2008; 2009 and Geeraerts (2007. We analyze five entries, one from each dictionary type 3.

  5. Dependency of radon entry on pressure difference

    Science.gov (United States)

    Kokotti, H.; Kalliokoski, P.; Jantunen, M.

    Radon levels, ventilation rate and pressure differences were monitored continuously in four apartment houses with different ventilation systems. Two of them were ventilated by mechanical exhaust, one by mechanical supply and exhaust, and one by natural ventilation. The two-storey houses were constructed from concrete elements on a slab and located on a gravel esker. It was surprising to find that increasing the ventilation rate increased levels of radon in the apartments. Increased ventilation caused increased outdoor-indoor pressure difference, which in turn increased the entry rate of radon and counteracted the diluting effect of ventilation. The increase was significant when the outdoor-indoor pressure difference exceeded 5 Pa. Especially in the houses with mechanical exhaust ventilation the pressure difference was the most important factor of radon entry rate, and contributed up to several hundred Bq m -3 h -1.

  6. Minimization of the transformer inter-winding parasitic capacitance for modular stacking power supply applications

    DEFF Research Database (Denmark)

    Nguyen-Duy, Khiem; Ouyang, Ziwei; Knott, Arnold;

    2014-01-01

    In an isolated power supply, the inter-winding parasitic capacitance plays a vital role in the mitigation of common mode noise currents created by fast voltage transient responses. The lower the transformer inter-winding capacitance, the more immune the power supply is to fast voltage transient r...

  7. A capacitive level shifter for high voltage (2.5kV)

    DEFF Research Database (Denmark)

    Andersen, Thomas; Andersen, Michael A. E.; Thomsen, Ole Cornelius;

    2012-01-01

    with focus on low power consumption as well as low capacitive load between the floating half-bridge node and ground (output capacitance). The operation of the level-shifter is tested and verified by measurements on a prototype half-bridge gate driver. Results conclude stabile operation at 2.44kV, 50k...

  8. A branch-and-cut-and-price algorithm for the cumulative capacitated vehicle routing problem

    DEFF Research Database (Denmark)

    Wøhlk, Sanne; Lysgaard, Jens

    2014-01-01

    The paper considers the Cumulative Capacitated Vehicle Routing Problem (CCVRP), which is a variation of the well-known Capacitated Vehicle Routing Problem (CVRP). In this problem, the traditional objective of minimizing total distance or time traveled by the vehicles is replaced by minimizing...

  9. An iterated tabu search heuristic for the Single Source Capacitated Facility Location Problem

    DEFF Research Database (Denmark)

    Ho, Sin C.

    2015-01-01

    This paper discusses the Single Source Capacitated Facility Location Problem (SSCFLP) where the problem consists in determining a subset of capacitated facilities to be opened in order to satisfy the customers’ demands such that total costs are minimized. The paper presents an iterated tabu search...

  10. Polycrystalline VO{sub 2} film characterization by quantum capacitance measurement

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhe; Knighton, Talbot, E-mail: talbot.knighton@wayne.edu; Tarquini, Vinicio; Huang, Jian [Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201 (United States); Torres, David; Wang, Tongyu; Sepúlveda, Nelson [Electrical and Computer Engineering Department, Michigan State University, East Lansing, Michigan 48824 (United States)

    2015-09-07

    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.

  11. Faster Time Response by the Use of Wire Electrodes in Capacitive Salinity Gradient Energy Systems

    NARCIS (Netherlands)

    Burheim, O.S.; Liu, F.; Sales, B.B.; Schaetzle, O.; Buisman, C.J.N.; Hamelers, H.V.M.

    2012-01-01

    Capacitive energy extraction based on Donnan potential (CDP) and capacitive energy extraction based on double layer expansion (CDLE) are novel electroctrochemical processes to convert the potential free energy of mixing sea and river water into electric work. This is done by the use of supercapacito

  12. The polarizability and the capacitance change of a bounded object in a parallel plate capacitor

    Science.gov (United States)

    Kristensson, Gerhard

    2012-09-01

    A method for solving the change in capacitance (or charge) if an object is introduced in a parallel plate capacitor is developed. The integral representation of the potential is exploited in a systematic way to solve the potential everywhere inside the capacitor. In particular, the change in capacitance is extracted. The method shows similarities with the null field approach for solving dynamic problems.

  13. Capacitance-voltage characteristics of GaAs ion-implanted structures

    Directory of Open Access Journals (Sweden)

    Privalov E. N.

    2008-08-01

    Full Text Available A noniterative numerical method is proposed to calculate the barrier capacitance of GaAs ion-implanted structures as a function of the Schottky barrier bias. The features of the low- and high-frequency capacitance-voltage characteristics of these structures which are due to the presence of deep traps are elucidated.

  14. Advanced Restricted Area Entry Control System (Araecs)

    Science.gov (United States)

    2014-06-01

    the standardized effect of each factor on the response. The red line in Figure 9 is the statistically significant threshold for an alpha value of 0.05...system. The red line indicates the secure area boundary. Figure 14. Overall Conceptual View of ARAECS (1) Prime Directive. Entry control and...template information is not readable from the smart card. With this technique, the smart card must be microcontroller (as opposed to just memory) based

  15. Hypersonic Flight Mechanics. [for atmospheric entry trajectories

    Science.gov (United States)

    Busemann, A.; Vinh, N. X.; Culp, R. D.

    1976-01-01

    The effects of aerodynamic forces on trajectories at orbital speeds are discussed in terms of atmospheric models. The assumptions for the model are spherical symmetry, nonrotating, and an exponential atmosphere. The equations of flight, and the performance in extra-atmospheric flight are discussed along with the return to the atmosphere, and the entry. Solutions of the exact equations using directly matched asymptotic expansions are presented.

  16. Unified treatment of lifting atmospheric entry

    Science.gov (United States)

    Nachtsheim, P. R.; Lehman, L. L.

    1980-01-01

    This paper presents a unified treatment of the effect of lift on peak acceleration during atmospheric entry. Earlier studies were restricted to different regimes because of approximations invoked to solve the same transcendental equation. This paper shows the connection between the earlier studies by employing a general expression for the peak acceleration and obtains solutions to the transcendental equation without invoking the earlier approximations. Results are presented and compared with earlier studies where appropriate.

  17. Kinetics of virus entry by endocytosis

    Science.gov (United States)

    Zhdanov, Vladimir P.

    2015-04-01

    Entry of virions into the host cells is either endocytotic or fusogenic. In both cases, it occurs via reversible formation of numerous relatively weak bonds resulting in wrapping of a virion by the host membrane with subsequent membrane rupture or scission. The corresponding kinetic models are customarily focused on the formation of bonds and do not pay attention to the energetics of the whole process, which is crucially dependent, especially in the case of endocytosis, on deformation of actin filaments forming the cytoskeleton of the host cell. The kinetic model of endocytosis, proposed by the author, takes this factor into account and shows that the whole process can be divided into a rapid initial transient stage and a long steady-state stage. The entry occurs during the latter stage and can be described as a first-order reaction. Depending on the details of the dependence of the grand canonical potential on the number of bonds, the entry can be limited either by the interplay of bond formation and membrane rupture (or scission) or by reaching a maximum of this potential.

  18. Filovirus tropism: Cellular molecules for viral entry

    Directory of Open Access Journals (Sweden)

    Ayato eTakada

    2012-02-01

    Full Text Available In human and nonhuman primates, filoviruses (Ebola and Marburg viruses cause severe hemorrhagic fever.Recently, other animals such as pigs and some species of fruit bats have also been shown to be susceptible to these viruses. While having a preference for some cell types such as hepatocytes, endothelial cells, dendritic cells, monocytes, and macrophages, filoviruses are known to be pantropic in infection of primates. The envelope glycoprotein (GP is responsible for both receptor binding and fusion of the virus envelope with the host cell membrane. It has been demonstrated that filovirus GP interacts with multiple molecules for entry into host cells, whereas none of the cellular molecules so far identified as a receptor/coreceptor fully explains filovirus tissue tropism and host range. Available data suggest that the mucin-like region (MLR on GP plays an important role in attachment to the preferred target cells, whose infection is likely involved in filovirus pathogenesis, whereas the MLR is not essential for the fundamental function of the GP in viral entry into cells in vitro. Further studies elucidating the mechanisms of cellular entry of filoviruses may shed light on the development of strategies for prophylaxis and treatment of Ebola and Marburg hemorrhagic fevers.

  19. Nuclear Chk1 prevents premature mitotic entry.

    Science.gov (United States)

    Matsuyama, Makoto; Goto, Hidemasa; Kasahara, Kousuke; Kawakami, Yoshitaka; Nakanishi, Makoto; Kiyono, Tohru; Goshima, Naoki; Inagaki, Masaki

    2011-07-01

    Chk1 inhibits the premature activation of the cyclin-B1-Cdk1. However, it remains controversial whether Chk1 inhibits Cdk1 in the centrosome or in the nucleus before the G2-M transition. In this study, we examined the specificity of the mouse monoclonal anti-Chk1 antibody DCS-310, with which the centrosome was stained. Conditional Chk1 knockout in mouse embryonic fibroblasts reduced nuclear but not centrosomal staining with DCS-310. In Chk1(+/myc) human colon adenocarcinoma (DLD-1) cells, Chk1 was detected in the nucleus but not in the centrosome using an anti-Myc antibody. Through the combination of protein array and RNAi technologies, we identified Ccdc-151 as a protein that crossreacted with DCS-310 on the centrosome. Mitotic entry was delayed by expression of the Chk1 mutant that localized in the nucleus, although forced immobilization of Chk1 to the centrosome had little impact on the timing of mitotic entry. These results suggest that nuclear but not centrosomal Chk1 contributes to correct timing of mitotic entry.

  20. Cell entry by human pathogenic arenaviruses.

    Science.gov (United States)

    Rojek, Jillian M; Kunz, Stefan

    2008-04-01

    The arenaviruses Lassa virus (LASV) in Africa and Machupo (MACV), Guanarito (GTOV) and Junin viruses (JUNV) in South America cause severe haemorrhagic fevers in humans with fatality rates of 15-35%. The present review focuses on the first steps of infection with human pathogenic arenaviruses, the interaction with their cellular receptor molecules and subsequent entry into the host cell. While similarities exist in genomic organization, structure and clinical disease caused by pathogenic Old World and New World arenaviruses these pathogens use different primary receptors. The Old World arenaviruses employ alpha-dystroglycan, a cellular receptor for proteins of the extracellular matrix, and the human pathogenic New World arenaviruses use the cellular cargo receptor transferrin receptor 1. While the New World arenavirus JUNV enters cells via clathrin-dependent endocytosis, evidence occurred for clathrin-independent entry of the prototypic Old World arenavirus lymphocytic choriomeningitis virus. Upon internalization, arenaviruses are delivered to the endosome, where pH-dependent membrane fusion is mediated by the envelope glycoprotein (GP). While arenavirus GPs share characteristics with class I fusion GPs of other enveloped viruses, unusual mechanistic features of GP-mediated membrane fusion have recently been discovered for arenaviruses with important implications for viral entry.

  1. 19 CFR 149.6 - Entry and entry summary documentation and Importer Security Filing submitted via a single...

    Science.gov (United States)

    2010-04-01

    ... Security Filing submitted via a single electronic transmission. 149.6 Section 149.6 Customs Duties U.S... submitted via a single electronic transmission. If the Importer Security Filing is filed pursuant to § 149.2 of this part via the same electronic transmission as entry or entry/entry summary...

  2. Electron heating in low pressure capacitive discharges revisited

    Science.gov (United States)

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

    2014-12-01

    The electrons in capacitively coupled plasmas (CCPs) absorb energy via ohmic heating due to electron-neutral collisions and stochastic heating due to momentum transfer from high voltage moving sheaths. We use Particle-in-Cell (PIC) simulations to explore these heating mechanisms and to compare the PIC results with available theories on ohmic and stochastic heating. The PIC results for ohmic heating show good agreement with the ohmic heating calculation of Lafleur et al. [Phys. Plasmas 20, 124503 (2013)]. The PIC results for stochastic heating in low pressure CCPs with collisionless sheaths show good agreement with the stochastic heating model of Kaganovich et al. [IEEE Trans. Plasma Sci. 34, 696 (2006)], which revises the hard wall asymptotic model of Lieberman [IEEE Trans. Plasma Sci. 16, 638 (1988)] by taking current continuity and bulk oscillation into account.

  3. A novel heuristic algorithm for capacitated vehicle routing problem

    Science.gov (United States)

    Kır, Sena; Yazgan, Harun Reşit; Tüncel, Emre

    2017-02-01

    The vehicle routing problem with the capacity constraints was considered in this paper. It is quite difficult to achieve an optimal solution with traditional optimization methods by reason of the high computational complexity for large-scale problems. Consequently, new heuristic or metaheuristic approaches have been developed to solve this problem. In this paper, we constructed a new heuristic algorithm based on the tabu search and adaptive large neighborhood search (ALNS) with several specifically designed operators and features to solve the capacitated vehicle routing problem (CVRP). The effectiveness of the proposed algorithm was illustrated on the benchmark problems. The algorithm provides a better performance on large-scaled instances and gained advantage in terms of CPU time. In addition, we solved a real-life CVRP using the proposed algorithm and found the encouraging results by comparison with the current situation that the company is in.

  4. Enhanced capacitive deionization of graphene/mesoporous carbon composites

    Science.gov (United States)

    Zhang, Dengsong; Wen, Xiaoru; Shi, Liyi; Yan, Tingting; Zhang, Jianping

    2012-08-01

    Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are well retained and the composites display improved specific surface area and pore size distribution, as well as pore volume. Well dispersed GE nanosheets are deduced to be beneficial for enhanced electrical conductivity. The electrochemical performance of electrodes in an NaCl aqueous solution was characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrodes perform better on the capacitance values, conductive behaviour, rate performance and cyclic stability. The desalination capacity of the electrodes was evaluated by a batch mode electrosorptive experiment and the amount of adsorbed ions can reach 731 μg g-1 for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 μg g-1). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area.Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are

  5. Advances in Modern Capacitive ECG Systems for Continuous Cardiovascular Monitoring

    Directory of Open Access Journals (Sweden)

    A. Schommartz

    2011-01-01

    Full Text Available The technique of capacitive electrocardiography (cECG is very promising in a flexible manner. Already integrated into several everyday objects, the single lead cECG system has shown that easy-to-use measurements of electrocardiograms are possible without difficult preparation of the patients. Multi-channel cECG systems enable the extraction of ECG signals even in the presence of coupled interferences, due to the additional redundant information. Thus, this paper presents challenges for electronic hardware design to build on developments in recent years, going from the one-lead cECG system to multi-channel systems in order to provide robust measurements - e.g. even while driving an automobile.

  6. Interaction phenomena in graphene seen through quantum capacitance.

    Science.gov (United States)

    Yu, G L; Jalil, R; Belle, Branson; Mayorov, Alexander S; Blake, Peter; Schedin, Frederick; Morozov, Sergey V; Ponomarenko, Leonid A; Chiappini, F; Wiedmann, S; Zeitler, Uli; Katsnelson, Mikhail I; Geim, A K; Novoselov, Kostya S; Elias, Daniel C

    2013-02-26

    Capacitance measurements provide a powerful means of probing the density of states. The technique has proved particularly successful in studying 2D electron systems, revealing a number of interesting many-body effects. Here, we use large-area high-quality graphene capacitors to study behavior of the density of states in this material in zero and high magnetic fields. Clear renormalization of the linear spectrum due to electron-electron interactions is observed in zero field. Quantizing fields lead to splitting of the spin- and valley-degenerate Landau levels into quartets separated by interaction-enhanced energy gaps. These many-body states exhibit negative compressibility but the compressibility returns to positive in ultrahigh B. The reentrant behavior is attributed to a competition between field-enhanced interactions and nascent fractional states.

  7. Improved Circuits with Capacitive Feedback for Readout Resistive Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Óscar Oballe-Peinado

    2016-01-01

    Full Text Available One of the most suitable ways of distributing a resistive sensor array for reading is an array with M rows and N columns. This allows reduced wiring and a certain degree of parallelism in the implementation, although it also introduces crosstalk effects. Several types of circuits can carry out the analogue-digital conversion of this type of sensors. This article focuses on the use of operational amplifiers with capacitive feedback and FPGAs for this task. Specifically, modifications of a previously reported circuit are proposed to reduce the errors due to the non-idealities of the amplifiers and the I/O drivers of the FPGA. Moreover, calibration algorithms are derived from the analysis of the proposed circuitry to reduce the crosstalk error and improve the accuracy. Finally, the performances of the proposals is evaluated experimentally on an array of resistors and for different ranges.

  8. A novel design of micromachined capacitive Lamb wave transducers

    Science.gov (United States)

    Ge, Lifeng

    2006-11-01

    A new design for micromachined capacitive Lamb wave transducers (mCLWT) has been developed. The design is based on a theoretical TDK model previously developed for groove ultrasonic transducers. By the investigation of the dynamic behavior of a rectangular high aspect ratio diaphragm of the mCLWTs, the second order bending mode of the diaphragm is exploited to excite and detect Lamb wave. The new exiting mechanism can minimize the energy of the acoustic radiation at the normal direction of the diaphragm so as to provide more energy coupled into the Lamb wave in the silicon substrate. Also, the natural frequencies and mode shapes of such a mCLWT can be determined accurately from its geometry and materials used, so the TDK model provides guidance for the optimal design of mCLWTs.

  9. Frequency scanning capaciflector for capacitively determining the material properties

    Science.gov (United States)

    Campbell, Charles E. (Inventor)

    1996-01-01

    A capaciflector sensor system scanned in frequency is used to detect the permittivity of the material of an object being sensed. A capaciflector sensor element, coupled to current-measuring voltage follower circuitry, is driven by a frequency swept oscillator and generates an output which corresponds to capacity as a function of the input frequency. This swept frequency information is fed into apparatus e.g. a digital computer for comparing the shape of the capacitance vs. frequency curve against characteristic capacitor vs. frequency curves for a variety of different materials which are stored, for example, in a digital memory of the computer or a database. Using a technique of pattern matching, a determination is made as to the identification of the material. Also, when desirable, the distance between the sensor and the object can be determined.

  10. Capacitively coupled hybrid pixel assemblies for the CLIC vertex detector

    CERN Document Server

    AUTHOR|(SzGeCERN)734627; Benoit, Mathieu; Dannheim, Dominik; Dette, Karola; Hynds, Daniel; Kulis, Szymon; Peric, Ivan; Petric, Marko; Redford, Sophie; Sicking, Eva; Valerio, Pierpaolo

    2016-01-01

    The vertex detector at the proposed CLIC multi-TeV linear e+e- collider must have minimal material content and high spatial resolution, combined with accurate time-stamping to cope with the expected high rate of beam-induced backgrounds. One of the options being considered is the use of active sensors implemented in a commercial high-voltage CMOS process, capacitively coupled to hybrid pixel ASICs. A prototype of such an assembly, using two custom designed chips (CCPDv3 as active sensor glued to a CLICpix readout chip), has been characterised both in the lab and in beam tests at the CERN SPS using 120 GeV/c positively charged hadrons. Results of these characterisation studies are presented both for single and dual amplification stages in the active sensor. Pixel cross-coupling results are also presented, showing the sensitivity to placement precision and planarity of the glue layer.

  11. A Tagless Indoor Localization System Based on Capacitive Sensing Technology

    Directory of Open Access Journals (Sweden)

    Alireza Ramezani Akhmareh

    2016-09-01

    Full Text Available Accurate indoor person localization is essential for several services, such as assisted living. We introduce a tagless indoor person localization system based on capacitive sensing and localization algorithms that can determine the location with less than 0.2 m average error in a 3 m × 3 m room and has recall and precision better than 70%. We also discuss the effects of various noise types on the measurements and ways to reduce them using filters suitable for on-sensor implementation to lower communication energy consumption. We also compare the performance of several standard localization algorithms in terms of localization error, recall, precision, and accuracy of detection of the movement trajectory.

  12. Using MEMS Capacitive Switches in Tunable RF Amplifiers

    Directory of Open Access Journals (Sweden)

    Danson John

    2006-01-01

    Full Text Available A MEMS capacitive switch suitable for use in tunable RF amplifiers is described. A MEMS switch is designed, fabricated, and characterized with physical and RF measurements for inclusion in simulations. Using the MEMS switch models, a dual-band low-noise amplifier (LNA operating at GHz and GHz, and a tunable power amplifier (PA at GHz are simulated in m CMOS. MEMS switches allow the LNA to operate with 11 dB of isolation between the two bands while maintaining dB of gain and sub- dB noise figure. MEMS switches are used to implement a variable matching network that allows the PA to realize up to 37% PAE improvement at low input powers.

  13. Analysis of new actuation methods for capacitive shunt micro switchs

    Directory of Open Access Journals (Sweden)

    Ben Sassi S

    2016-01-01

    Full Text Available This work investigates the use of new actuation methods in capacitive shunt micro switches. We formulate the coupled electromechanical problem by taking into account the fringing effects and nonlinearities due to mid-plane stretching. Static analysis is undertaken using the Differential Quadrature Method (DQM to obtain the pull in voltage which is verified by means of the Finite Element Method (FEM. Based on Galerkin approximation, a single degree of freedom dynamic model is developed and limit-cycle solutions are calculated using the Finite Difference Method (FDM. In addition to the harmonic waveform signal, we apply novel actuation waveform signals to simulate the frequency-response. We show that, biased signals, using a square wave signal reduces significantly the pull-in voltage compared to the triangular and harmonic signal . Finally, these results are validated experimentally.

  14. Transport of Sputtered Particles in Capacitive Sputter Sources

    CERN Document Server

    Trieschmann, Jan

    2015-01-01

    The transport of sputtered aluminum inside a multi frequency capacitively coupled plasma chamber is simulated by means of a kinetic test multi-particle approach. A novel consistent set of scattering parameters obtained for a modified variable hard sphere collision model is presented for both argon and aluminum. An angular dependent Thompson energy distribution is fitted to results from Monte-Carlo simulations and used for the kinetic simulation of the transport of sputtered aluminum. For the proposed configuration the transport of sputtered particles is characterized under typical process conditions at a gas pressure of p = 0.5 Pa. It is found that - due to the peculiar geometric conditions - the transport can be understood in a one dimensional picture, governed by the interaction of the imposed and backscattered particle fluxes. It is shown that the precise geometric features play an important role only in proximity to the electrode edges, where the effect of backscattering from the outside chamber volume be...

  15. Attractive forces in microporous carbon electrodes for capacitive deionization

    CERN Document Server

    Biesheuvel, P M; Levi, M; Bazant, M Z

    2013-01-01

    The recently developed modified Donnan (mD) model provides a simple and useful description of the electrical double layer in microporous carbon electrodes, suitable for incorporation in porous electrode theory. By postulating an attractive excess chemical potential for each ion in the micropores that is inversely proportional to the total ion concentration, we show that experimental data for capacitive deionization (CDI) can be accurately predicted over a wide range of applied voltages and salt concentrations. Since the ion spacing and Bjerrum length are each comparable to the micropore size (few nm), we postulate that the attraction results from fluctuating bare Coulomb interactions between individual ions and the metallic pore surfaces (image forces) that are not captured by meanfield theories, such as the Poisson-Boltzmann-Stern model or its mathematical limit for overlapping double layers, the Donnan model. Using reasonable estimates of the micropore permittivity and mean size (and no other fitting parame...

  16. Capacitive immunosensor for C-reactive protein quantification

    KAUST Repository

    Sapsanis, Christos

    2015-08-02

    We report an agglutination-based immunosensor for the quantification of C-reactive protein (CRP). The developed immunoassay sensor requires approximately 15 minutes of assay time per sample and provides a sensitivity of 0.5 mg/L. We have measured the capacitance of interdigitated electrodes (IDEs) and quantified the concentration of added analyte. The proposed method is a label free detection method and hence provides rapid measurement preferable in diagnostics. We have so far been able to quantify the concentration to as low as 0.5 mg/L and as high as 10 mg/L. By quantifying CRP in serum, we can assess whether patients are prone to cardiac diseases and monitor the risk associated with such diseases. The sensor is a simple low cost structure and it can be a promising device for rapid and sensitive detection of disease markers at the point-of-care stage.

  17. A Memetic Algorithm for the Capacitated Location-Routing Problem

    Directory of Open Access Journals (Sweden)

    Laila KECHMANE

    2016-06-01

    Full Text Available In this paper, a hybrid genetic algorithm is proposed to solve a Capacitated Location-Routing Problem. The objective is to minimize the total cost of the distribution in a network composed of depots and customers, both depots and vehicles have limited capacities, each depot has a homogenous vehicle fleet and customers’ demands are known and must be satisfied. Solving this problem involves making strategic decisions such as the location of depots, as well as tactical and operational decisions which include assigning customers to the opened depots and organization of the vehicle routing. To evaluate the performance of the proposed algorithm, its results are compared to those obtained by a greedy randomized adaptive search procedure, computational results shows that the algorithm gave good quality solutions.

  18. Variable neighbourhood simulated annealing algorithm for capacitated vehicle routing problems

    Science.gov (United States)

    Xiao, Yiyong; Zhao, Qiuhong; Kaku, Ikou; Mladenovic, Nenad

    2014-04-01

    This article presents the variable neighbourhood simulated annealing (VNSA) algorithm, a variant of the variable neighbourhood search (VNS) combined with simulated annealing (SA), for efficiently solving capacitated vehicle routing problems (CVRPs). In the new algorithm, the deterministic 'Move or not' criterion of the original VNS algorithm regarding the incumbent replacement is replaced by an SA probability, and the neighbourhood shifting of the original VNS (from near to far by k← k+1) is replaced by a neighbourhood shaking procedure following a specified rule. The geographical neighbourhood structure is introduced in constructing the neighbourhood structures for the CVRP of the string model. The proposed algorithm is tested against 39 well-known benchmark CVRP instances of different scales (small/middle, large, very large). The results show that the VNSA algorithm outperforms most existing algorithms in terms of computational effectiveness and efficiency, showing good performance in solving large and very large CVRPs.

  19. Characterization of active CMOS sensors for capacitively coupled pixel detectors

    Energy Technology Data Exchange (ETDEWEB)

    Hirono, Toko; Gonella, Laura; Janssen, Jens; Hemperek, Tomasz; Huegging, Fabian; Krueger, Hans; Wermes, Norbert [Institute of Physics, University of Bonn (Germany); Peric, Ivan [Institut fuer Prozessdatenverarbeitung und Elektronik, Karlsruher Institut fuer Technologie, Karlsruhe (Germany)

    2015-07-01

    Active CMOS pixel sensor is one of the most attractive candidates for detectors of upcoming particle physics experiments. In contrast to conventional sensors of hybrid detectors, signal processing circuit can be integrated in the active CMOS sensor. The characterization and optimization of the pixel circuit are indispensable to obtain a good performance from the sensors. The prototype chips of the active CMOS sensor were fabricated in the AMS 180nm and L-Foundry 150 nm CMOS processes, respectively a high voltage and high resistivity technology. Both chips have a charge sensitive amplifier and a comparator in each pixel. The chips are designed to be glued to the FEI4 pixel readout chip. The signals from 3 pixels of the prototype chips are capacitively coupled to the FEI4 input pads. We have performed lab tests and test beams to characterize the prototypes. In this presentation, the measurement results of the active CMOS prototype sensors are shown.

  20. Capacitance probe for detection of anomalies in non-metallic plastic pipe

    Science.gov (United States)

    Mathur, Mahendra P.; Spenik, James L.; Condon, Christopher M.; Anderson, Rodney; Driscoll, Daniel J.; Fincham, Jr., William L.; Monazam, Esmail R.

    2010-11-23

    The disclosure relates to analysis of materials using a capacitive sensor to detect anomalies through comparison of measured capacitances. The capacitive sensor is used in conjunction with a capacitance measurement device, a location device, and a processor in order to generate a capacitance versus location output which may be inspected for the detection and localization of anomalies within the material under test. The components may be carried as payload on an inspection vehicle which may traverse through a pipe interior, allowing evaluation of nonmetallic or plastic pipes when the piping exterior is not accessible. In an embodiment, supporting components are solid-state devices powered by a low voltage on-board power supply, providing for use in environments where voltage levels may be restricted.