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Sample records for voltage sensor s4

  1. Stabilization of the Activated hERG Channel Voltage Sensor by Depolarization Involves the S4-S5 Linker.

    Science.gov (United States)

    Thouta, Samrat; Hull, Christina M; Shi, Yu Patrick; Sergeev, Valentine; Young, James; Cheng, Yen M; Claydon, Thomas W

    2017-01-24

    Slow deactivation of hERG channels is critical for preventing cardiac arrhythmia yet the mechanistic basis for the slow gating transition is unclear. Here, we characterized the temporal sequence of events leading to voltage sensor stabilization upon membrane depolarization. Progressive increase in step depolarization duration slowed voltage-sensor return in a biphasic manner (τfast = 34 ms, τslow = 2.5 s). The faster phase of voltage-sensor return slowing correlated with the kinetics of pore opening. The slower component occurred over durations that exceeded channel activation and was consistent with voltage sensor relaxation. The S4-S5 linker mutation, G546L, impeded the faster phase of voltage sensor stabilization without attenuating the slower phase, suggesting that the S4-S5 linker is important for communications between the pore gate and the voltage sensor during deactivation. These data also demonstrate that the mechanisms of pore gate-opening-induced and relaxation-induced voltage-sensor stabilization are separable. Deletion of the distal N-terminus (Δ2-135) accelerated off-gating current, but did not influence the relative contribution of either mechanism of stabilization of the voltage sensor. Lastly, we characterized mode-shift behavior in hERG channels, which results from stabilization of activated channel states. The apparent mode-shift depended greatly on recording conditions. By measuring slow activation and deactivation at steady state we found the "true" mode-shift to be ∼15 mV. Interestingly, the "true" mode-shift of gating currents was ∼40 mV, much greater than that of the pore gate. This demonstrates that voltage sensor return is less energetically favorable upon repolarization than pore gate closure. We interpret this to indicate that stabilization of the activated voltage sensor limits the return of hERG channels to rest. The data suggest that this stabilization occurs as a result of reconfiguration of the pore gate upon opening by

  2. Mutations within the S4-S5 linker alter voltage sensor constraints in hERG K+ channels.

    Science.gov (United States)

    Van Slyke, Aaron C; Rezazadeh, Saman; Snopkowski, Mischa; Shi, Patrick; Allard, Charlene R; Claydon, Tom W

    2010-11-03

    Human ether-a-go-go related gene (hERG) channel gating is associated with slow activation, yet the mechanistic basis for this is unclear. Here, we examine the effects of mutation of a unique glycine residue (G546) in the S4-S5 linker on voltage sensor movement and its coupling to pore gating. Substitution of G546 with residues possessing different physicochemical properties shifted activation gating by ∼-50 mV (with the exception of G546C). With the activation shift taken into account, the time constant of activation was also accelerated, suggesting a stabilization of the closed state by ∼1.6-4.3 kcal/mol (the energy equivalent of one to two hydrogen bonds). Predictions of the α-helical content of the S4-S5 linker suggest that the presence of G546 in wild-type hERG provides flexibility to the helix. Deactivation gating was affected differentially by the G546 substitutions. G546V induced a pronounced slow component of closing that was voltage-independent. Fluorescence measurements of voltage sensor movement in G546V revealed a slow component of voltage sensor return that was uncoupled from charge movement, suggesting a direct effect of the mutation on voltage sensor movement. These data suggest that G546 plays a critical role in channel gating and that hERG channel closing involves at least two independently modifiable reconfigurations of the voltage sensor.

  3. PIP2 controls voltage-sensor movement and pore opening of Kv channels through the S4-S5 linker.

    Science.gov (United States)

    Rodriguez-Menchaca, Aldo A; Adney, Scott K; Tang, Qiong-Yao; Meng, Xuan-Yu; Rosenhouse-Dantsker, Avia; Cui, Meng; Logothetis, Diomedes E

    2012-09-04

    Voltage-gated K(+) (Kv) channels couple the movement of a voltage sensor to the channel gate(s) via a helical intracellular region, the S4-S5 linker. A number of studies link voltage sensitivity to interactions of S4 charges with membrane phospholipids in the outer leaflet of the bilayer. Although the phospholipid phosphatidylinositol-4,5-bisphosphate (PIP(2)) in the inner membrane leaflet has emerged as a universal activator of ion channels, no such role has been established for mammalian Kv channels. Here we show that PIP(2) depletion induced two kinetically distinct effects on Kv channels: an increase in voltage sensitivity and a concomitant decrease in current amplitude. These effects are reversible, exhibiting distinct molecular determinants and sensitivities to PIP(2). Gating current measurements revealed that PIP(2) constrains the movement of the sensor through interactions with the S4-S5 linker. Thus, PIP(2) controls both the movement of the voltage sensor and the stability of the open pore through interactions with the linker that connects them.

  4. Coupling between residues on S4 and S1 defines the voltage-sensor resting conformation in NaChBac.

    Science.gov (United States)

    Paldi, Tzur; Gurevitz, Michael

    2010-07-21

    The voltage sensor is a four-transmembrane helix bundle (S1-S4) that couples changes in membrane potential to conformational alterations in voltage-gated ion channels leading to pore opening and ion conductance. Although the structure of the voltage sensor in activated potassium channels is available, the conformation of the voltage sensor at rest is still obscure, limiting our understanding of the voltage-sensing mechanism. By employing a heterologously expressed Bacillus halodurans sodium channel (NaChBac), we defined constraints that affect the positioning and depolarization-induced outward motion of the S4 segment. We compared macroscopic currents mediated by NaChBac and mutants in which E43 on the S1 segment and the two outermost arginines (R1 and R2) on S4 were substituted. Neutralization of the negatively charged E43 (E43C) had a significant effect on channel gating. A double-mutant cycle analysis of E43 and R1 or R2 suggested changes in pairing during channel activation, implying that the interaction of E43 with R1 stabilizes the voltage sensor in its closed/available state, whereas interaction of E43 with R2 stabilizes the channel open/unavailable state. These constraints on S4 dynamics that define its stepwise movement upon channel activation and positioning at rest are novel, to the best of our knowledge, and compatible with the helical-screw and electrostatic models of S4 motion.

  5. The S4-S5 linker directly couples voltage sensor movement to the activation gate in the human ether-a'-go-go-related gene (hERG) K+ channel.

    Science.gov (United States)

    Ferrer, Tania; Rupp, Jason; Piper, David R; Tristani-Firouzi, Martin

    2006-05-05

    A key unresolved question regarding the basic function of voltage-gated ion channels is how movement of the voltage sensor is coupled to channel opening. We previously proposed that the S4-S5 linker couples voltage sensor movement to the S6 domain in the human ether-a'-go-go-related gene (hERG) K+ channel. The recently solved crystal structure of the voltage-gated Kv1.2 channel reveals that the S4-S5 linker is the structural link between the voltage sensing and pore domains. In this study, we used chimeras constructed from hERG and ether-a'-go-go (EAG) channels to identify interactions between residues in the S4-S5 linker and S6 domain that were critical for stabilizing the channel in a closed state. To verify the spatial proximity of these regions, we introduced cysteines in the S4-S5 linker and at the C-terminal end of the S6 domain and then probed for the effect of oxidation. The D540C-L666C channel current decreased in an oxidizing environment in a state-dependent manner consistent with formation of a disulfide bond that locked the channel in a closed state. Disulfide bond formation also restricted movement of the voltage sensor, as measured by gating currents. Taken together, these data confirm that the S4-S5 linker directly couples voltage sensor movement to the activation gate. Moreover, rather than functioning simply as a mechanical lever, these findings imply that specific interactions between the S4-S5 linker and the activation gate stabilize the closed channel conformation.

  6. Molecular dissection of the contribution of negatively and positively charged residues in S2, S3, and S4 to the final membrane topology of the voltage sensor in the K+ channel, KAT1.

    Science.gov (United States)

    Sato, Yoko; Sakaguchi, Masao; Goshima, Shinobu; Nakamura, Tatsunosuke; Uozumi, Nobuyuki

    2003-04-11

    Voltage-dependent ion channels control changes in ion permeability in response to membrane potential changes. The voltage sensor in channel proteins consists of the highly positively charged segment, S4, and the negatively charged segments, S2 and S3. The process involved in the integration of the protein into the membrane remains to be elucidated. In this study, we used in vitro translation and translocation experiments to evaluate interactions between residues in the voltage sensor of a hyperpolarization-activated potassium channel, KAT1, and their effect on the final topology in the endoplasmic reticulum (ER) membrane. A D95V mutation in S2 showed less S3-S4 integration into the membrane, whereas a D105V mutation allowed S4 to be released into the ER lumen. These results indicate that Asp(95) assists in the membrane insertion of S3-S4 and that Asp(105) helps in preventing S4 from being releasing into the ER lumen. The charge reversal mutation, R171D, in S4 rescued the D105R mutation and prevented S4 release into the ER lumen. A series of constructs containing different C-terminal truncations of S4 showed that Arg(174) was required for correct integration of S3 and S4 into the membrane. Interactions between Asp(105) and Arg(171) and between negative residues in S2 or S3 and Arg(174) may be formed transiently during membrane integration. These data clarify the role of charged residues in S2, S3, and S4 and identify posttranslational electrostatic interactions between charged residues that are required to achieve the correct voltage sensor topology in the ER membrane.

  7. Functionality of the voltage-gated proton channel truncated in S4.

    Science.gov (United States)

    Sakata, Souhei; Kurokawa, Tatsuki; Nørholm, Morten H H; Takagi, Masahiro; Okochi, Yoshifumi; von Heijne, Gunnar; Okamura, Yasushi

    2010-02-02

    The voltage sensor domain (VSD) is the key module for voltage sensing in voltage-gated ion channels and voltage-sensing phosphatases. Structurally, both the VSD and the recently discovered voltage-gated proton channels (Hv channels) voltage sensor only protein (VSOP) and Hv1 contain four transmembrane segments. The fourth transmembrane segment (S4) of Hv channels contains three periodically aligned arginines (R1, R2, R3). It remains unknown where protons permeate or how voltage sensing is coupled to ion permeation in Hv channels. Here we report that Hv channels truncated just downstream of R2 in the S4 segment retain most channel properties. Two assays, site-directed cysteine-scanning using accessibility of maleimide-reagent as detected by Western blotting and insertion into dog pancreas microsomes, both showed that S4 inserts into the membrane, even if it is truncated between the R2 and R3 positions. These findings provide important clues to the molecular mechanism underlying voltage sensing and proton permeation in Hv channels.

  8. KCNQ1 Channels Voltage Dependence through a Voltage-dependent Binding of the S4-S5 Linker to the Pore Domain*

    OpenAIRE

    2010-01-01

    Voltage-dependent potassium (Kv) channels are tetramers of six transmembrane domain (S1–S6) proteins. Crystallographic data demonstrate that the tetrameric pore (S5–S6) is surrounded by four voltage sensor domains (S1–S4). One key question remains: how do voltage sensors (S4) regulate pore gating? Previous mutagenesis data obtained on the Kv channel KCNQ1 highlighted the critical role of specific residues in both the S4-S5 linker (S4S5L) and S6 C terminus (S6T). From these data, we hypothesiz...

  9. The S4-S5 linker couples voltage sensing and activation of pacemaker channels.

    Science.gov (United States)

    Chen, J; Mitcheson, J S; Tristani-Firouzi, M; Lin, M; Sanguinetti, M C

    2001-09-25

    Voltage-gated channels are normally opened by depolarization and closed by repolarization of the membrane. Despite sharing significant sequence homology with voltage-gated K(+) channels, the gating of hyperpolarization-activated, cyclic-nucleotide-gated (HCN) pacemaker channels has the opposite dependence on membrane potential: hyperpolarization opens, whereas depolarization closes, these channels. The mechanism and structural basis of the process that couples voltage sensor movement to HCN channel opening and closing is not understood. On the basis of our previous studies of a mutant HERG (human ether-a-go-go-related gene) channel, we hypothesized that the intracellular linker that connects the fourth and fifth transmembrane domains (S4-S5 linker) of HCN channels might be important for channel gating. Here, we used alanine-scanning mutagenesis of the HCN2 S4-S5 linker to identify three residues, E324, Y331, and R339, that when mutated disrupted normal channel closing. Mutation of a basic residue in the S4 domain (R318Q) prevented channel opening, presumably by disrupting S4 movement. However, channels with R318Q and Y331S mutations were constitutively open, suggesting that these channels can open without a functioning S4 domain. We conclude that the S4-S5 linker mediates coupling between voltage sensing and HCN channel activation. Our findings also suggest that opening of HCN and related channels corresponds to activation of a gate located near the inner pore, rather than recovery of channels from a C-type inactivated state.

  10. Voltage Sensors Monitor Harmful Static

    Science.gov (United States)

    2009-01-01

    A tiny sensor, small enough to be worn on clothing, now monitors voltage changes near sensitive instruments after being created to alert Agency workers to dangerous static buildup near fuel operations and avionics. San Diego s Quasar Federal Systems received a Small Business Innovation Research (SBIR) contract from Kennedy Space Center to develop its remote voltage sensor (RVS), a dime-sized electrometer designed to measure triboelectric changes in the environment. One of the unique qualities of the RVS is that it can detect static at greater distances than previous devices, measuring voltage changes from a few centimeters to a few meters away, due to its much-improved sensitivity.

  11. KCNQ1 channels voltage dependence through a voltage-dependent binding of the S4-S5 linker to the pore domain.

    Science.gov (United States)

    Choveau, Frank S; Rodriguez, Nicolas; Abderemane Ali, Fayal; Labro, Alain J; Rose, Thierry; Dahimène, Shehrazade; Boudin, Hélène; Le Hénaff, Carole; Escande, Denis; Snyders, Dirk J; Charpentier, Flavien; Mérot, Jean; Baró, Isabelle; Loussouarn, Gildas

    2011-01-07

    Voltage-dependent potassium (Kv) channels are tetramers of six transmembrane domain (S1-S6) proteins. Crystallographic data demonstrate that the tetrameric pore (S5-S6) is surrounded by four voltage sensor domains (S1-S4). One key question remains: how do voltage sensors (S4) regulate pore gating? Previous mutagenesis data obtained on the Kv channel KCNQ1 highlighted the critical role of specific residues in both the S4-S5 linker (S4S5(L)) and S6 C terminus (S6(T)). From these data, we hypothesized that S4S5(L) behaves like a ligand specifically interacting with S6(T) and stabilizing the closed state. To test this hypothesis, we designed plasmid-encoded peptides corresponding to portions of S4S5(L) and S6(T) of the voltage-gated potassium channel KCNQ1 and evaluated their effects on the channel activity in the presence and absence of the ancillary subunit KCNE1. We showed that S4S5(L) peptides inhibit KCNQ1, in a reversible and state-dependent manner. S4S5(L) peptides also inhibited a voltage-independent KCNQ1 mutant. This inhibition was competitively prevented by a peptide mimicking S6(T), consistent with S4S5(L) binding to S6(T). Val(254) in S4S5(L) is known to contact Leu(353) in S6(T) when the channel is closed, and mutations of these residues alter the coupling between the two regions. The same mutations introduced in peptides altered their effects, further confirming S4S5(L) binding to S6(T). Our results suggest a mechanistic model in which S4S5(L) acts as a voltage-dependent ligand bound to its receptor on S6 at rest. This interaction locks the channel in a closed state. Upon plasma membrane depolarization, S4 pulls S4S5(L) away from S6(T), allowing channel opening.

  12. CONTRIBUTIONS OF INTRACELLULAR IONS TO Kv CHANNEL VOLTAGE SENSOR DYNAMICS.

    Directory of Open Access Journals (Sweden)

    Samuel eGoodchild

    2012-06-01

    Full Text Available Voltage sensing domains of Kv channels control ionic conductance through coupling of the movement of charged residues in the S4 segment to conformational changes at the cytoplasmic region of the pore domain, that allow K+ ions to flow. Conformational transitions within the voltage sensing domain caused by changes in the applied voltage across the membrane field are coupled to the conducting pore region and the gating of ionic conductance. However, several other factors not directly linked to the voltage dependent movement of charged residues within the voltage sensor impact the dynamics of the voltage sensor, such as inactivation, ionic conductance, intracellular ion identity and block of the channel by intracellular ligands. The effect of intracellular ions on voltage sensor dynamics is of importance in the interpretation of gating current measurements and the physiology of pore/voltage sensor coupling. There is a significant amount of variability in the reported kinetics of voltage sensor deactivation kinetics of Kv channels attributed to different mechanisms such as open state stabilization, immobilization and relaxation processes of the voltage sensor. Here we separate these factors and focus on the causal role that intracellular ions can play in allosterically modulating the dynamics of Kv voltage sensor deactivation kinetics. These considerations are of critical importance in understanding the molecular determinants of the complete channel gating cycle from activation to deactivation.

  13. hERG S4-S5 linker acts as a voltage-dependent ligand that binds to the activation gate and locks it in a closed state.

    Science.gov (United States)

    Malak, Olfat A; Es-Salah-Lamoureux, Zeineb; Loussouarn, Gildas

    2017-12-01

    Delayed-rectifier potassium channels (hERG and KCNQ1) play a major role in cardiac repolarization. These channels are formed by a tetrameric pore (S5-S6) surrounded by four voltage sensor domains (S1-S4). Coupling between voltage sensor domains and the pore activation gate is critical for channel voltage-dependence. However, molecular mechanisms remain elusive. Herein, we demonstrate that covalently binding, through a disulfide bridge, a peptide mimicking the S4-S5 linker (S4-S5L) to the channel S6 C-terminus (S6T) completely inhibits hERG. This shows that channel S4-S5L is sufficient to stabilize the pore activation gate in its closed state. Conversely, covalently binding a peptide mimicking S6T to the channel S4-S5L prevents its inhibiting effect and renders the channel almost completely voltage-independent. This shows that the channel S4-S5L is necessary to stabilize the activation gate in its closed state. Altogether, our results provide chemical evidence that S4-S5L acts as a voltage-controlled ligand that binds S6T to lock the channel in a closed state, elucidating the coupling between voltage sensors and the gate in delayed rectifier potassium channels and potentially other voltage-gated channels.

  14. Structural interactions between lipids, water and S1-S4 voltage-sensing domains.

    Science.gov (United States)

    Krepkiy, Dmitriy; Gawrisch, Klaus; Swartz, Kenton J

    2012-11-01

    Membrane proteins serve crucial signaling and transport functions, yet relatively little is known about their structures in membrane environments or how lipids interact with these proteins. For voltage-activated ion channels, X-ray structures suggest that the mobile voltage-sensing S4 helix would be exposed to the membrane, and functional studies reveal that lipid modification can profoundly alter channel activity. Here, we use solid-state NMR to investigate structural interactions of lipids and water with S1-S4 voltage-sensing domains and to explore whether lipids influence the structure of the protein. Our results demonstrate that S1-S4 domains exhibit extensive interactions with lipids and that these domains are heavily hydrated when embedded in a membrane. We also find evidence for preferential interactions of anionic lipids with S1-S4 domains and that these interactions have lifetimes on the timescale of ≤ 10(-3)s. Arg residues within S1-S4 domains are well hydrated and are positioned in close proximity to lipids, exhibiting local interactions with both lipid headgroups and acyl chains. Comparative studies with a positively charged lipid lacking a phosphodiester group reveal that this lipid modification has only modest effects on the structure and hydration of S1-S4 domains. Taken together, our results demonstrate that Arg residues in S1-S4 voltage-sensing domains reside in close proximity to the hydrophobic interior of the membrane yet are well hydrated, a requirement for carrying charge and driving protein motions in response to changes in membrane voltage.

  15. Arrangement and mobility of the voltage sensor domain in prokaryotic voltage-gated sodium channels.

    Science.gov (United States)

    Shimomura, Takushi; Irie, Katsumasa; Nagura, Hitoshi; Imai, Tomoya; Fujiyoshi, Yoshinori

    2011-03-04

    Prokaryotic voltage-gated sodium channels (Na(V)s) form homotetramers with each subunit contributing six transmembrane α-helices (S1-S6). Helices S5 and S6 form the ion-conducting pore, and helices S1-S4 function as the voltage sensor with helix S4 thought to be the essential element for voltage-dependent activation. Although the crystal structures have provided insight into voltage-gated K channels (K(V)s), revealing a characteristic domain arrangement in which the voltage sensor domain of one subunit is close to the pore domain of an adjacent subunit in the tetramer, the structural and functional information on Na(V)s remains limited. Here, we show that the domain arrangement in NaChBac, a firstly cloned prokaryotic Na(V), is similar to that in K(V)s. Cysteine substitutions of three residues in helix S4, Q107C, T110C, and R113C, effectively induced intersubunit disulfide bond formation with a cysteine introduced in helix S5, M164C, of the adjacent subunit. In addition, substituting two acidic residues with lysine, E43K and D60K, shifted the activation of the channel to more positive membrane potentials and consistently shifted the preferentially formed disulfide bond from T110C/M164C to Q107C/M164C. Because Gln-107 is located closer to the extracellular side of helix S4 than Thr-110, this finding suggests that the functional shift in the voltage dependence of activation is related to a restriction of the position of helix S4 in the lipid bilayer. The domain arrangement and vertical mobility of helix S4 in NaChBac indicate that the structure and the mechanism of voltage-dependent activation in prokaryotic Na(V)s are similar to those in canonical K(V)s.

  16. Non-contact current and voltage sensor

    Science.gov (United States)

    Carpenter, Gary D; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C; Schappert, Michael A

    2014-03-25

    A detachable current and voltage sensor provides an isolated and convenient device to measure current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing that contains the current and voltage sensors, which may be a ferrite cylinder with a hall effect sensor disposed in a gap along the circumference to measure current, or alternative a winding provided through the cylinder along its axis and a capacitive plate or wire disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

  17. The effects of S4 segments on the voltage-dependence of inactivation for Cav3.1 calcium channels

    Institute of Scientific and Technical Information of China (English)

    LI JunYing

    2007-01-01

    T-type calcium channels exhibit fast voltage-dependent inactivation,for which the underlying structure-function relationship still remains unclear.To investigate the roles of S4 segments in voltage-dependent inactivation of T-type calcium channels,we created S4 replacement chimeras between Cav3.1 calcium channels(fast voltage-dependent inactivation)and Cav1.2 calcium channels(little oltage-dependent inactivation)by replacing S4s in Cav3.1 with the corresponding regions in Cav1.2.Wild type and chimeric channels were expressed in Xenopus oocytes and channel currents were recorded with two-electrode voltage-clamp.We showed that replacing S4 region in domain I shifted voltage-dependence for inactivation of Cav3.1 to the left,and the V0.5 inact and kinact value were significantly changed.However replacing S4s in domains Ⅱ-Ⅳ had no effects on the voltage-dependent inactivation properties.These results suggest that the roles of S4 segments in domains Ⅰ-Ⅳ are different,and S4 in domain I is likely to be involved in voltage-dependent Inactivation process.Its movement during membrane depolarization may trigger a conformational change in the inactivation gate.

  18. The Cu2ZnSnS4 solar cell with high open circuit voltage

    Science.gov (United States)

    Yang, Min; Ma, Xun; Jiang, Zhi; Li, Zhishan; Liu, Sijia; Lu, Yilei; Wang, Shurong

    2017-03-01

    In this paper, the effects of two different sulfurization processes on the CZTS films were investigated, and the results indicated that a rapid high-temperature crystallization process after sulfurization was beneficial for CZTS thin films to obtain a compact and flat surface with large grains. However, a common sulfurization without rapid high-temperature crystallization process would easily lead to undesirable properties of films, such as rough surface with pin holes, which degenerate the performance of devices. Cu2ZnSnS4 (CZTS) solar cell based on a rapid high-temperature process after sulfurization achieved a high open circuit voltage of 722 mV and the best efficiency 3.32% was obtained.

  19. Intermediate state trapping of a voltage sensor

    DEFF Research Database (Denmark)

    Lacroix, Jérôme J; Pless, Stephan Alexander; Maragliano, Luca

    2012-01-01

    Voltage sensor domains (VSDs) regulate ion channels and enzymes by undergoing conformational changes depending on membrane electrical signals. The molecular mechanisms underlying the VSD transitions are not fully understood. Here, we show that some mutations of I241 in the S1 segment of the Shaker...... Kv channel positively shift the voltage dependence of the VSD movement and alter the functional coupling between VSD and pore domains. Among the I241 mutants, I241W immobilized the VSD movement during activation and deactivation, approximately halfway between the resting and active states......, and drastically shifted the voltage activation of the ionic conductance. This phenotype, which is consistent with a stabilization of an intermediate VSD conformation by the I241W mutation, was diminished by the charge-conserving R2K mutation but not by the charge-neutralizing R2Q mutation. Interestingly, most...

  20. Voltage-sensor mutations in channelopathies of skeletal muscle

    Science.gov (United States)

    Cannon, Stephen C

    2010-01-01

    Mutations of voltage-gated ion channels cause several channelopathies of skeletal muscle, which present clinically with myotonia, periodic paralysis, or a combination of both. Expression studies have revealed both loss-of-function and gain-of-function defects for the currents passed by mutant channels. In many cases, these functional changes could be mechanistically linked to the defects of fibre excitability underlying myotonia or periodic paralysis. One remaining enigma was the basis for depolarization-induced weakness in hypokalaemic periodic paralysis (HypoPP) arising from mutations in either sodium or calcium channels. Curiously, 14 of 15 HypoPP mutations are at arginines in S4 voltage sensors, and recent observations show that these substitutions support an alternative pathway for ion conduction, the gating pore, that may be the source of the aberrant depolarization during an attack of paralysis. PMID:20156847

  1. Capacitor Voltages Measurement and Balancing in Flying Capacitor Multilevel Converters Utilizing a Single Voltage Sensor

    DEFF Research Database (Denmark)

    Farivar, Glen; Ghias, Amer M. Y. M.; Hredzak, Branislav

    2017-01-01

    This paper proposes a new method for measuring capacitor voltages in multilevel flying capacitor (FC) converters that requires only one voltage sensor per phase leg. Multiple dc voltage sensors traditionally used to measure the capacitor voltages are replaced with a single voltage sensor at the ac...... side of the phase leg. The proposed method is subsequently used to balance the capacitor voltages using only the measured ac voltage. The operation of the proposed measurement and balancing method is independent of the number of the converter levels. Experimental results presented for a five-level FC...

  2. Interface band gap narrowing behind open circuit voltage losses in Cu2ZnSnS4 solar cells

    DEFF Research Database (Denmark)

    Crovetto, Andrea; Palsgaard, Mattias Lau Nøhr; Gunst, Tue

    2017-01-01

    We present evidence that bandgap narrowing at the heterointerface may be a major cause of the large open circuit voltage deficit of Cu2ZnSnS4/CdS solar cells. Bandgap narrowing is caused by surface states that extend the Cu2ZnSnS4valence band into the forbidden gap. Those surface states are consi......We present evidence that bandgap narrowing at the heterointerface may be a major cause of the large open circuit voltage deficit of Cu2ZnSnS4/CdS solar cells. Bandgap narrowing is caused by surface states that extend the Cu2ZnSnS4valence band into the forbidden gap. Those surface states...... Zn to passivate those surface states. Focusing future research on Zn-based buffers is expected to significantly improve the open circuit voltage and efficiency of pure-sulfide Cu2ZnSnS4 solar cells....

  3. Niflumic acid alters gating of HCN2 pacemaker channels by interaction with the outer region of S4 voltage sensing domains.

    Science.gov (United States)

    Cheng, Lan; Sanguinetti, Michael C

    2009-05-01

    Niflumic acid, 2-[[3-(trifluoromethyl)phenyl]amino]pyridine-3-carboxylic acid (NFA), is a nonsteroidal anti-inflammatory drug that also blocks or modifies the gating of many ion channels. Here, we investigated the effects of NFA on hyperpolarization-activated cyclic nucleotide-gated cation (HCN) pacemaker channels expressed in X. laevis oocytes using site-directed mutagenesis and the two-electrode voltage-clamp technique. Extracellular NFA acted rapidly and caused a slowing of activation and deactivation and a hyperpolarizing shift in the voltage dependence of HCN2 channel activation (-24.5 +/- 1.2 mV at 1 mM). Slowed channel gating and reduction of current magnitude was marked in oocytes treated with NFA, while clamped at 0 mV but minimal in oocytes clamped at -100 mV, indicating the drug preferentially interacts with channels in the closed state. NFA at 0.1 to 3 mM shifted the half-point for channel activation in a concentration-dependent manner, with an EC(50) of 0.54 +/- 0.068 mM and a predicted maximum shift of -38 mV. NFA at 1 mM also reduced maximum HCN2 conductance by approximately 20%, presumably by direct block of the pore. The rapid onset and state-dependence of NFA-induced changes in channel gating suggests an interaction with the extracellular region of the S4 transmembrane helix, the primary voltage-sensing domain of HCN2. Neutralization (by mutation to Gln) of any three of the outer four basic charged residues in S4, but not single mutations, abrogated the NFA-induced shift in channel activation. We conclude that NFA alters HCN2 gating by interacting with the extracellular end of the S4 voltage sensor domains.

  4. Molecular Action of Lidocaine on the Voltage Sensors of Sodium Channels

    OpenAIRE

    Sheets, Michael F.; Hanck, Dorothy A

    2003-01-01

    Block of sodium ionic current by lidocaine is associated with alteration of the gating charge-voltage (Q-V) relationship characterized by a 38% reduction in maximal gating charge (Qmax) and by the appearance of additional gating charge at negative test potentials. We investigated the molecular basis of the lidocaine-induced reduction in cardiac Na channel–gating charge by sequentially neutralizing basic residues in each of the voltage sensors (S4 segments) in the four domains of the human hea...

  5. Reversal of HCN channel voltage dependence via bridging of the S4-S5 linker and Post-S6.

    Science.gov (United States)

    Prole, David L; Yellen, Gary

    2006-09-01

    Voltage-gated ion channels possess charged domains that move in response to changes in transmembrane voltage. How this movement is transduced into gating of the channel pore is largely unknown. Here we show directly that two functionally important regions of the spHCN1 pacemaker channel, the S4-S5 linker and the C-linker, come into close proximity during gating. Cross-linking these regions with high-affinity metal bridges or disulfide bridges dramatically alters channel gating in the absence of cAMP; after modification the polarity of voltage dependence is reversed. Instead of being closed at positive voltage and activating with hyperpolarization, modified channels are closed at negative voltage and activate with depolarization. Mechanistically, this reversal of voltage dependence occurs as a result of selectively eliminating channel deactivation, while retaining an existing inactivation process. Bridging also alters channel activation by cAMP, showing that interaction of these two regions can also affect the efficacy of physiological ligands.

  6. S3-S4 linker length modulates the relaxed state of a voltage-gated potassium channel.

    Science.gov (United States)

    Priest, Michael F; Lacroix, Jérôme J; Villalba-Galea, Carlos A; Bezanilla, Francisco

    2013-11-19

    Voltage-sensing domains (VSDs) are membrane protein modules found in ion channels and enzymes that are responsible for a large number of fundamental biological tasks, such as neuronal electrical activity. The VSDs switch from a resting to an active conformation upon membrane depolarization, altering the activity of the protein in response to voltage changes. Interestingly, numerous studies describe the existence of a third distinct state, called the relaxed state, also populated at positive potentials. Although some physiological roles for the relaxed state have been suggested, little is known about the molecular determinants responsible for the development and modulation of VSD relaxation. Several lines of evidence have suggested that the linker (S3-S4 linker) between the third (S3) and fourth (S4) transmembrane segments of the VSD alters the equilibrium between resting and active conformations. By measuring gating currents from the Shaker potassium channel, we demonstrate here that shortening the S3-S4 linker stabilizes the relaxed state, whereas lengthening the linker or splitting it and coinjecting two fragments of the channel have little effect. We propose that natural variations of the length of the S3-S4 linker in various VSD-containing proteins may produce differential VSD relaxation in vivo.

  7. Research and Experiments on a Unipolar Capacitive Voltage Sensor

    Directory of Open Access Journals (Sweden)

    Qiang Zhou

    2015-08-01

    Full Text Available Voltage sensors are an important part of the electric system. In service, traditional voltage sensors need to directly contact a high-voltage charged body. Sensors involve a large volume, complex insulation structures, and high design costs. Typically an iron core structure is adopted. As a result, ferromagnetic resonance can occur easily during practical application. Moreover, owing to the multilevel capacitor divider, the sensor cannot reflect the changes of measured voltage in time. Based on the electric field coupling principle, this paper designs a new voltage sensor; the unipolar structure design solves many problems of traditional voltage sensors like the great insulation design difficulty and high costs caused by grounding electrodes. A differential signal input structure is adopted for the detection circuit, which effectively restrains the influence of the common-mode interference signal. Through sensor modeling, simulation and calculations, the structural design of the sensor electrode was optimized, miniaturization of the sensor was realized, the voltage division ratio of the sensor was enhanced, and the phase difference of sensor measurement was weakened. The voltage sensor is applied to a single-phase voltage class line of 10 kV for testing. According to the test results, the designed sensor is able to meet the requirements of accurate and real-time measurement for voltage of the charged conductor as well as to provide a new method for electricity larceny prevention and on-line monitoring of the power grid in an electric system. Therefore, it can satisfy the development demands of the smart power grid.

  8. Structure and function of the voltage sensor of sodium channels probed by a beta-scorpion toxin.

    Science.gov (United States)

    Cestèle, Sandrine; Yarov-Yarovoy, Vladimir; Qu, Yusheng; Sampieri, François; Scheuer, Todd; Catterall, William A

    2006-07-28

    Voltage sensing by voltage-gated sodium channels determines the electrical excitability of cells, but the molecular mechanism is unknown. beta-Scorpion toxins bind specifically to neurotoxin receptor site 4 and induce a negative shift in the voltage dependence of activation through a voltage sensor-trapping mechanism. Kinetic analysis showed that beta-scorpion toxin binds to the resting state, and subsequently the bound toxin traps the voltage sensor in the activated state in a voltage-dependent but concentration-independent manner. The rate of voltage sensor trapping can be fit by a two-step model, in which the first step is voltage-dependent and correlates with the outward gating movement of the IIS4 segment, whereas the second step is voltage-independent and results in shifted voltage dependence of activation of the channel. Mutations of Glu(779) in extracellular loop IIS1-S2 and both Glu(837) and Leu(840) in extracellular loop IIS3-S4 reduce the binding affinity of beta-scorpion toxin. Mutations of positively charged and hydrophobic amino acid residues in the IIS4 segment do not affect beta-scorpion toxin binding but alter voltage dependence of activation and enhance beta-scorpion toxin action. Structural modeling with the Rosetta algorithm yielded a three-dimensional model of the toxin-receptor complex with the IIS4 voltage sensor at the extracellular surface. Our results provide mechanistic and structural insight into the voltage sensor-trapping mode of scorpion toxin action, define the position of the voltage sensor in the resting state of the sodium channel, and favor voltage-sensing models in which the S4 segment spans the membrane in both resting and activated states.

  9. Structure and Function of the Voltage Sensor of Sodium Channels Probed by a β-Scorpion Toxin*S

    Science.gov (United States)

    Cestèle, Sandrine; Yarov-Yarovoy, Vladimir; Qu, Yusheng; Sampieri, François; Scheuer, Todd; Catterall, William A.

    2006-01-01

    Voltage sensing by voltage-gated sodium channels determines the electrical excitability of cells, but the molecular mechanism is unknown. β-Scorpion toxins bind specifically to neurotoxin receptor site 4 and induce a negative shift in the voltage dependence of activation through a voltage sensor-trapping mechanism. Kinetic analysis showed that β-scorpion toxin binds to the resting state, and subsequently the bound toxin traps the voltage sensor in the activated state in a voltage-dependent but concentration-independent manner. The rate of voltage sensor trapping can be fit by a two-step model, in which the first step is voltage-dependent and correlates with the outward gating movement of the IIS4 segment, whereas the second step is voltage-independent and results in shifted voltage dependence of activation of the channel. Mutations of Glu779 in extracellular loop IIS1–S2 and both Glu837 and Leu840 in extracellular loop IIS3–S4 reduce the binding affinity of β-scorpion toxin. Mutations of positively charged and hydrophobic amino acid residues in the IIS4 segment do not affect β-scorpion toxin binding but alter voltage dependence of activation and enhance β-scorpion toxin action. Structural modeling with the Rosetta algorithm yielded a three-dimensional model of the toxin-receptor complex with the IIS4 voltage sensor at the extracellular surface. Our results provide mechanistic and structural insight into the voltage sensor-trapping mode of scorpion toxin action, define the position of the voltage sensor in the resting state of the sodium channel, and favor voltage-sensing models in which the S4 segment spans the membrane in both resting and activated states. PMID:16679310

  10. Optical voltage sensors: principle, problem and research proposal

    Science.gov (United States)

    Li, Changsheng

    2016-10-01

    Sensing principles and main problems to be solved for optical voltage sensors are briefly reviewed. Optical effects used for voltage sensing usually include electro-optic Pockels and Kerr effects, electro-gyration effect, elasto-optical effect, and electroluminescent effects, etc. In principle, typical optical voltage sensor is based on electro-optic Pockels crystals and closed-loop signal detection scheme. Main problems to be solved for optical voltage sensors include: how to remove influence of unwanted multiple optical effects on voltage sensing performance; how to select or develop a proper voltage sensing material and element; how to keep optical phase bias to be stable under temperature fluctuation and vibration; how to achieve dc voltage sensing, etc. In order to suppress the influence of unwanted optical effects and light beam coupling-related loss on voltage sensing signals, we may pay more attention to all-fiber and waveguide voltage sensors. Voltage sensors based on electroluminescent effects are also promising in some application fields due to their compact configuration, low cost and potential long-term reliability.

  11. Proton currents constrain structural models of voltage sensor activation

    Science.gov (United States)

    Randolph, Aaron L; Mokrab, Younes; Bennett, Ashley L; Sansom, Mark SP; Ramsey, Ian Scott

    2016-01-01

    The Hv1 proton channel is evidently unique among voltage sensor domain proteins in mediating an intrinsic ‘aqueous’ H+ conductance (GAQ). Mutation of a highly conserved ‘gating charge’ residue in the S4 helix (R1H) confers a resting-state H+ ‘shuttle’ conductance (GSH) in VGCs and Ci VSP, and we now report that R1H is sufficient to reconstitute GSH in Hv1 without abrogating GAQ. Second-site mutations in S3 (D185A/H) and S4 (N4R) experimentally separate GSH and GAQ gating, which report thermodynamically distinct initial and final steps, respectively, in the Hv1 activation pathway. The effects of Hv1 mutations on GSH and GAQ are used to constrain the positions of key side chains in resting- and activated-state VS model structures, providing new insights into the structural basis of VS activation and H+ transfer mechanisms in Hv1. DOI: http://dx.doi.org/10.7554/eLife.18017.001 PMID:27572256

  12. Functional interaction between S1 and S4 segments in voltage-gated sodium channels revealed by human channelopathies.

    Science.gov (United States)

    Amarouch, Mohamed-Yassine; Kasimova, Marina A; Tarek, Mounir; Abriel, Hugues

    2014-01-01

    The p.I141V mutation of the voltage-gated sodium channel is associated with several clinical hyper-excitability phenotypes. To understand the structural bases of the p.I141V biophysical alterations, molecular dynamics simulations were performed. These simulations predicted that the p.I141V substitution induces the formation of a hydrogen bond between the Y168 residue of the S2 segment and the R225 residue of the S4 segment. We generated a p.I141V-Y168F double mutant for both the Nav1.4 and Nav1.5 channels. The double mutants demonstrated the abolition of the functional effects of the p.I141V mutation, consistent with the formation of a specific interaction between Y168-S2 and R225-S4. The single p.Y168F mutation, however, positively shifted the activation curve, suggesting a compensatory role of these residues on the stability of the voltage-sensing domain.

  13. Molecular basis of the interaction between gating modifier spider toxins and the voltage sensor of voltage-gated ion channels

    Science.gov (United States)

    Lau, Carus H. Y.; King, Glenn F.; Mobli, Mehdi

    2016-01-01

    Voltage-sensor domains (VSDs) are modular transmembrane domains of voltage-gated ion channels that respond to changes in membrane potential by undergoing conformational changes that are coupled to gating of the ion-conducting pore. Most spider-venom peptides function as gating modifiers by binding to the VSDs of voltage-gated channels and trapping them in a closed or open state. To understand the molecular basis underlying this mode of action, we used nuclear magnetic resonance to delineate the atomic details of the interaction between the VSD of the voltage-gated potassium channel KvAP and the spider-venom peptide VSTx1. Our data reveal that the toxin interacts with residues in an aqueous cleft formed between the extracellular S1-S2 and S3-S4 loops of the VSD whilst maintaining lipid interactions in the gaps formed between the S1-S4 and S2-S3 helices. The resulting network of interactions increases the energetic barrier to the conformational changes required for channel gating, and we propose that this is the mechanism by which gating modifier toxins inhibit voltage-gated ion channels. PMID:27677715

  14. Molecular basis of the interaction between gating modifier spider toxins and the voltage sensor of voltage-gated ion channels

    Science.gov (United States)

    Lau, Carus H. Y.; King, Glenn F.; Mobli, Mehdi

    2016-09-01

    Voltage-sensor domains (VSDs) are modular transmembrane domains of voltage-gated ion channels that respond to changes in membrane potential by undergoing conformational changes that are coupled to gating of the ion-conducting pore. Most spider-venom peptides function as gating modifiers by binding to the VSDs of voltage-gated channels and trapping them in a closed or open state. To understand the molecular basis underlying this mode of action, we used nuclear magnetic resonance to delineate the atomic details of the interaction between the VSD of the voltage-gated potassium channel KvAP and the spider-venom peptide VSTx1. Our data reveal that the toxin interacts with residues in an aqueous cleft formed between the extracellular S1-S2 and S3-S4 loops of the VSD whilst maintaining lipid interactions in the gaps formed between the S1-S4 and S2-S3 helices. The resulting network of interactions increases the energetic barrier to the conformational changes required for channel gating, and we propose that this is the mechanism by which gating modifier toxins inhibit voltage-gated ion channels.

  15. Alternative splicing modulates inactivation of type 1 voltage-gated sodium channels by toggling an amino acid in the first S3-S4 linker.

    Science.gov (United States)

    Fletcher, Emily V; Kullmann, Dimitri M; Schorge, Stephanie

    2011-10-21

    Voltage-gated sodium channels underlie the upstroke of action potentials and are fundamental to neuronal excitability. Small changes in the behavior of these channels are sufficient to change neuronal firing and trigger seizures. These channels are subject to highly conserved alternative splicing, affecting the short linker between the third transmembrane segment (S3) and the voltage sensor (S4) in their first domain. The biophysical consequences of this alternative splicing are incompletely understood. Here we focus on type 1 sodium channels (Nav1.1) that are implicated in human epilepsy. We show that the functional consequences of alternative splicing are highly sensitive to recording conditions, including the identity of the major intracellular anion and the recording temperature. In particular, the inactivation kinetics of channels containing the alternate exon 5N are more sensitive to intracellular fluoride ions and to changing temperature than channels containing exon 5A. Moreover, Nav1.1 channels containing exon 5N recover from inactivation more rapidly at physiological temperatures. Three amino acids differ between exons 5A and 5N. However, the changes in sensitivity and stability of inactivation were reproduced by a single conserved change from aspartate to asparagine in channels containing exon 5A, which was sufficient to make them behave like channels containing the complete exon 5N sequence. These data suggest that splicing at this site can modify the inactivation of sodium channels and reveal a possible interaction between splicing and anti-epileptic drugs that stabilize sodium channel inactivation.

  16. Engineering of a Genetically Encodable Fluorescent Voltage Sensor Exploiting Fast Ci-VSP Voltage-Sensing Movements

    OpenAIRE

    Alicia Lundby; Hiroki Mutoh; Dimitar Dimitrov; Walther Akemann; Thomas Knöpfel

    2008-01-01

    Ci-VSP contains a voltage-sensing domain (VSD) homologous to that of voltage-gated potassium channels. Using charge displacement ('gating' current) measurements we show that voltage-sensing movements of this VSD can occur within 1 ms in mammalian membranes. Our analysis lead to development of a genetically encodable fluorescent protein voltage sensor (VSFP) in which the fast, voltage-dependent conformational changes of the Ci-VSP voltage sensor are transduced to similarly fast fluorescence re...

  17. Voltage Sensors in Hypokalemic Periodic Paralysis

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2009-06-01

    Full Text Available Researchers at the National Hospital, Queen Square, London, UK, conducted automated DNA sequencing of the S4 regions of CACNA1S and SCN4A in 83 patients with hypokalemic periodic paralysis (HypoPP.

  18. A torsional sensor for MEMS-based RMS voltage measurements

    Directory of Open Access Journals (Sweden)

    J. Dittmer

    2008-05-01

    Full Text Available RF voltage measurement based on electrostatic RMS voltage-to-force conversion is an alternative method in comparison to the conventional thermal power dissipation method. It is based on a mechanical force induced by an RF voltage applied to a micro-mechanical system. For a theoretically adequate resolution and high precision measurements, the necessary geometrical dimensions of the sensor require the application of micro machining. In this contribution, the dependence between electrical and geometrical properties of different sensor designs is investigated. Based on these results, problems related to practical micro-machining and solutions with respect to possible sensor realizations are discussed. The evolution of different sensor generations is shown.

  19. Voltage sensor charge loss accounts for most cases of hypokalemic periodic paralysis.

    Science.gov (United States)

    Matthews, E; Labrum, R; Sweeney, M G; Sud, R; Haworth, A; Chinnery, P F; Meola, G; Schorge, S; Kullmann, D M; Davis, M B; Hanna, M G

    2009-05-05

    Several missense mutations of CACNA1S and SCN4A genes occur in hypokalemic periodic paralysis. These mutations affect arginine residues in the S4 voltage sensors of the channel. Approximately 20% of cases remain genetically undefined. We undertook direct automated DNA sequencing of the S4 regions of CACNA1S and SCN4A in 83 cases of hypokalemic periodic paralysis. We identified reported CACNA1S mutations in 64 cases. In the remaining 19 cases, mutations in SCN4A or other CACNA1S S4 segments were found in 10, including three novel changes and the first mutations in channel domains I (SCN4A) and III (CACNA1S). All mutations affected arginine residues, consistent with the gating pore cation leak hypothesis of hypokalemic periodic paralysis. Arginine mutations in S4 segments underlie 90% of hypokalemic periodic paralysis cases.

  20. Tunable sensor response by voltage-control in biomimetic hair flow sensors

    NARCIS (Netherlands)

    Droogendijk, H.; Krijnen, G.J.M.

    2012-01-01

    We report improvements in detection limit and responsivity of biomimetic hair flow sensors by electrostatic spring-softening (ESS). Applying a DC-bias voltage to our capacitive flow sensors mediates large (80% and more) voltage-controlled electromechanical amplification of the flow signal for freque

  1. Tunable sensor response by voltage-control in biomimetic hair flow sensors

    NARCIS (Netherlands)

    Droogendijk, H.; Krijnen, G.J.M.

    2012-01-01

    We report improvements in detection limit and responsivity of biomimetic hair flow sensors by electrostatic spring-softening (ESS). Applying a DC-bias voltage to our capacitive flow sensors mediates large (80% and more) voltage-controlled electro-mechanical amplification of the flow signal for frequ

  2. Opposite Effects of the S4-S5 Linker and PIP(2) on Voltage-Gated Channel Function: KCNQ1/KCNE1 and Other Channels.

    Science.gov (United States)

    Choveau, Frank S; Abderemane-Ali, Fayal; Coyan, Fabien C; Es-Salah-Lamoureux, Zeineb; Baró, Isabelle; Loussouarn, Gildas

    2012-01-01

    Voltage-gated potassium (Kv) channels are tetramers, each subunit presenting six transmembrane segments (S1-S6), with each S1-S4 segments forming a voltage-sensing domain (VSD) and the four S5-S6 forming both the conduction pathway and its gate. S4 segments control the opening of the intracellular activation gate in response to changes in membrane potential. Crystal structures of several voltage-gated ion channels in combination with biophysical and mutagenesis studies highlighted the critical role of the S4-S5 linker (S4S5(L)) and of the S6 C-terminal part (S6(T)) in the coupling between the VSD and the activation gate. Several mechanisms have been proposed to describe the coupling at a molecular scale. This review summarizes the mechanisms suggested for various voltage-gated ion channels, including a mechanism that we described for KCNQ1, in which S4S5(L) is acting like a ligand binding to S6(T) to stabilize the channel in a closed state. As discussed in this review, this mechanism may explain the reverse response to depolarization in HCN-like channels. As opposed to S4S5(L), the phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PIP(2)), stabilizes KCNQ1 channel in an open state. Many other ion channels (not only voltage-gated) require PIP(2) to function properly, confirming its crucial importance as an ion channel cofactor. This is highlighted in cases in which an altered regulation of ion channels by PIP(2) leads to channelopathies, as observed for KCNQ1. This review summarizes the state of the art on the two regulatory mechanisms that are critical for KCNQ1 and other voltage-gated channels function (PIP(2) and S4S5(L)), and assesses their potential physiological and pathophysiological roles.

  3. Opposite effects of the S4-S5 linker and PIP2 on voltage-gated channel function: KCNQ1/KCNE1 and other channels

    Directory of Open Access Journals (Sweden)

    Frank S Choveau

    2012-07-01

    Full Text Available Voltage-gated potassium (Kv channels are tetramers, each subunit presenting six transmembrane segments (S1-S6, with each S1-S4 segments forming a voltage-sensing domain (VSD and the four S5-S6 forming both the conduction pathway and its gate. S4 segments control the opening of the intracellular activation gate in response to changes in membrane potential. Crystal structures of several voltage-gated ion channels in combination with biophysical and mutagenesis studies highlighted the critical role of the S4-S5 linker (S4S5L and of the S6 C-terminal part (S6T in the coupling between the VSD and the activation gate. Several mechanisms have been proposed to describe the coupling at a molecular scale. This review summarizes the mechanisms suggested for various voltage-gated ion channels, including a mechanism that we described for KCNQ1, in which S4S5L is acting like a ligand binding to S6T to stabilize the channel in a closed state. As discussed in this review, this mechanism may explain the reverse response to depolarization in HCN-like channels. As opposed to S4S5L, the phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PIP2, stabilizes KCNQ1 channel in an open state. Many other ion channels (not only voltage-gated require PIP2 to function properly, confirming its crucial importance as an ion channel co-factor. This is highlighted in cases in which an altered regulation of ion channels by PIP2 leads to channelopathies, as observed for KCNQ1. This review summarizes the state of the art on the two regulatory mechanisms that are critical for KCNQ1 and other voltage-gated channels function (PIP2 and S4-S5L, and assesses their potential physiological and pathophysiological roles.

  4. Time varying voltage combustion control and diagnostics sensor

    Science.gov (United States)

    Chorpening, Benjamin T.; Thornton, Jimmy D.; Huckaby, E. David; Fincham, William

    2011-04-19

    A time-varying voltage is applied to an electrode, or a pair of electrodes, of a sensor installed in a fuel nozzle disposed adjacent the combustion zone of a continuous combustion system, such as of the gas turbine engine type. The time-varying voltage induces a time-varying current in the flame which is measured and used to determine flame capacitance using AC electrical circuit analysis. Flame capacitance is used to accurately determine the position of the flame from the sensor and the fuel/air ratio. The fuel and/or air flow rate (s) is/are then adjusted to provide reduced flame instability problems such as flashback, combustion dynamics and lean blowout, as well as reduced emissions. The time-varying voltage may be an alternating voltage and the time-varying current may be an alternating current.

  5. A fiber optic hybrid multifunctional AC voltage sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sokolovsky, A.; Zadvornov, S. [IRE, Moscow (Russian Federation); Ryabko, M. [UFD, Moscow (Russian Federation)

    2008-07-01

    Hybrid sensors have the advantages of both electronic and optical technologies. Their sensing element is based on conventional transducers and the optical fiber is used as a transmission media for the optical signal encoded with information between the local module and the remote module. The power supply for the remote module is usually provided by a built-in photoelectric converter illuminated by the optical radiation going through the same or another optical fiber. Electro-optic hybrid sensors have been widely used because of the electrical isolation provided by optical fiber. In the conventional fiber optic voltage sensor, piezoelectric or electro-optic transducers are implemented. Processing and conditioning measurement information is a complex task in these sensors. Moreover, the considerable drawback of most of these systems is that only one parameter, usually voltage value, is measured. This paper presented a novel fiber optic hybrid sensor for alternating current voltage measurements. This instrument provides the simultaneous measurement of four parameters, notably voltage value, frequency, phase angle and the external temperature. The paper described the measurement technology of the instrument including the remote module and optical powering as well as the unique modulation algorithm. The results and conclusions were also presented. 7 refs., 4 figs.

  6. Temperature Induced Voltage Offset Drifts in Silicon Carbide Pressure Sensors

    Science.gov (United States)

    Okojie, Robert S.; Lukco, Dorothy; Nguyen, Vu; Savrun, Ender

    2012-01-01

    We report the reduction of transient drifts in the zero pressure offset voltage in silicon carbide (SiC) pressure sensors when operating at 600 C. The previously observed maximum drift of +/- 10 mV of the reference offset voltage at 600 C was reduced to within +/- 5 mV. The offset voltage drifts and bridge resistance changes over time at test temperature are explained in terms of the microstructure and phase changes occurring within the contact metallization, as analyzed by Auger electron spectroscopy and field emission scanning electron microscopy. The results have helped to identify the upper temperature reliable operational limit of this particular metallization scheme to be 605 C.

  7. Integration of Shaker-type K+ channel, KAT1, into the endoplasmic reticulum membrane: synergistic insertion of voltage-sensing segments, S3-S4, and independent insertion of pore-forming segments, S5-P-S6.

    Science.gov (United States)

    Sato, Yoko; Sakaguchi, Masao; Goshima, Shinobu; Nakamura, Tatsunosuke; Uozumi, Nobuyuki

    2002-01-08

    KAT1 is a member of the Shaker family of voltage-dependent K(+) channels, which has six transmembrane segments (called S1-S6), including an amphipathic S4 with several positively charged residues and a hydrophobic pore-forming region (called P) between S5 and S6. In this study, we systematically evaluated the function of individual and combined transmembrane segments of KAT1 to direct the final topology in the endoplasmic reticulum membrane by in vitro translation and translocation experiments. The assay with single-transmembrane constructs showed that S1 possesses the type II signal-anchor function, whereas S2 has the stop-transfer function. The properties fit well with the results derived from combined insertion of S1 and S2. S3 and S4 failed to integrate into the membrane by themselves. The inserted glycosylation sequence at the S3-S4 loop neither prevented the translocation of S3 and S4 nor impaired the function of voltage-dependent K(+) transport regardless of the changed length of the S3-S4 loop. S3 and S4 are likely to be posttranslationally integrated into the membrane only when somewhat specific interaction occurs between them. S5 had the ability of translocation reinitiation, and S6 had a strong preference for N(exo)/C(cyt) orientation. The pore region resided outside because of its lack of its transmembrane-spanning property. According to their own topogenic function, combined constructs of S5-P-S6 conferred the membrane-pore-membrane topology. This finding supports the notion that a set of S5-P-S6 can be independently integrated into the membrane. The results in this study provide the fundamental topogenesis mechanism of transmembrane segments involving voltage sensor and pore region in KAT1.

  8. Molecular Dynamics Simulations of Voltage Gated Cation Channels: Insights on Voltage-Sensor Domain Function and Modulation

    Directory of Open Access Journals (Sweden)

    Lucie eDelemotte

    2012-05-01

    Full Text Available Since their discovery in the 1950s, the structure and function of voltage gated cation channels (VGCC has been largely understood thanks to results stemming from electrophysiology, pharmacology, spectroscopy and structural biology. Over the past decade, computational methods such as molecular dynamics (MD simulations have also contributed, providing molecular level information that can be tested against experimental results, thereby allowing the validation of the models and protocols. Importantly, MD can shed light on elements of VGCC function that cannot be easily accessed through classical experiments. Here, we review the results of recent MD simulations addressing key questions that pertain to the function and modulation of the VGCC’s voltage sensor domain (VSD highlighting: 1 the movement of the S4-helix basic residues during channel activation, articulating how the electrical driving force acts upon them; 2 the nature of the VSD intermediate states on transitioning between open and closed states of the VGCC; and 3 the molecular level effects on the VSD arising from mutations of specific S4 positively charged residues involved in certain genetic diseases.

  9. Voltage dependence of Hodgkin-Huxley rate functions for a multistage K+ channel voltage sensor within a membrane

    Science.gov (United States)

    Vaccaro, S. R.

    2014-11-01

    The activation of a K+channel sensor in two sequential stages during a voltage clamp may be described as the translocation of a Brownian particle in an energy landscape with two large barriers between states. A solution of the Smoluchowski equation for a square-well approximation to the potential function of the S4 voltage sensor satisfies a master equation and has two frequencies that may be determined from the forward and backward rate functions. When the higher-frequency terms have small amplitude, the solution reduces to the relaxation of a rate equation, where the derived two-state rate functions are dependent on the relative magnitude of the forward rates (α and γ ) and the backward rates (β and δ ) for each stage. In particular, the voltage dependence of the Hodgkin-Huxley rate functions for a K+channel may be derived by assuming that the rate functions of the first stage are large relative to those of the second stage—α ≫γ and β ≫δ . For a Shaker IR K+ channel, the first forward and backward transitions are rate limiting (α <γ and δ ≪β ), and for an activation process with either two or three stages, the derived two-state rate functions also have a voltage dependence that is of a similar form to that determined for the squid axon. The potential variation generated by the interaction between a two-stage K+ ion channel and a noninactivating Na+ ion channel is determined by the master equation for K+channel activation and the ionic current equation when the Na+channel activation time is small, and if β ≪δ and α ≪γ , the system may exhibit a small amplitude oscillation between spikes, or mixed-mode oscillation, in which the slow closed state modulates the K+ ion channel conductance in the membrane.

  10. Lattice-matched Cu2ZnSnS4/CeO2 solar cell with open circuit voltage boost

    DEFF Research Database (Denmark)

    Crovetto, Andrea; Yan, Chang; Iandolo, Beniamino

    2016-01-01

    We report a reproducible enhancement of the open circuit voltage in Cu2ZnSnS4 solar cells by introduction of a very thin CeO2 interlayer between the Cu2ZnSnS4 absorber and the conventional CdS buffer. CeO2, a non-toxic earth-abundant compound, has a nearly optimal band alignment with Cu2ZnSnS4...... and the two materials are lattice-matched within 0.4%. This makes it possible to achieve an epitaxial interface when growing CeO2 by chemical bath deposition at temperatures as low as 50 °C. The open circuit voltage improvement is then attributed to a decrease in the interface recombination rate through...

  11. Lattice-matched Cu2ZnSnS4/CeO2 solar cell with open circuit voltage boost

    Science.gov (United States)

    Crovetto, Andrea; Yan, Chang; Iandolo, Beniamino; Zhou, Fangzhou; Stride, John; Schou, Jørgen; Hao, Xiaojing; Hansen, Ole

    2016-12-01

    We report a reproducible enhancement of the open circuit voltage in Cu2ZnSnS4 solar cells by introduction of a very thin CeO2 interlayer between the Cu2ZnSnS4 absorber and the conventional CdS buffer. CeO2, a non-toxic earth-abundant compound, has a nearly optimal band alignment with Cu2ZnSnS4 and the two materials are lattice-matched within 0.4%. This makes it possible to achieve an epitaxial interface when growing CeO2 by chemical bath deposition at temperatures as low as 50 °C. The open circuit voltage improvement is then attributed to a decrease in the interface recombination rate through formation of a high-quality heterointerface.

  12. Engineering of a genetically encodable fluorescent voltage sensor exploiting fast Ci-VSP voltage-sensing movements

    DEFF Research Database (Denmark)

    Lundby, Alicia; Mutoh, Hiroki; Dimitrov, Dimitar

    2008-01-01

    Ci-VSP contains a voltage-sensing domain (VSD) homologous to that of voltage-gated potassium channels. Using charge displacement ('gating' current) measurements we show that voltage-sensing movements of this VSD can occur within 1 ms in mammalian membranes. Our analysis lead to development of a g...... of a genetically encodable fluorescent protein voltage sensor (VSFP) in which the fast, voltage-dependent conformational changes of the Ci-VSP voltage sensor are transduced to similarly fast fluorescence read-outs....

  13. A Novel Voltage Sensor in the Orthosteric Binding Site of the M2 Muscarinic Receptor.

    Science.gov (United States)

    Barchad-Avitzur, Ofra; Priest, Michael F; Dekel, Noa; Bezanilla, Francisco; Parnas, Hanna; Ben-Chaim, Yair

    2016-10-04

    G protein-coupled receptors (GPCRs) mediate many signal transduction processes in the body. The discovery that these receptors are voltage-sensitive has changed our understanding of their behavior. The M2 muscarinic acetylcholine receptor (M2R) was found to exhibit depolarization-induced charge movement-associated currents, implying that this prototypical GPCR possesses a voltage sensor. However, the typical domain that serves as a voltage sensor in voltage-gated channels is not present in GPCRs, making the search for the voltage sensor in the latter challenging. Here, we examine the M2R and describe a voltage sensor that is comprised of tyrosine residues. This voltage sensor is crucial for the voltage dependence of agonist binding to the receptor. The tyrosine-based voltage sensor discovered here constitutes a noncanonical by which membrane proteins may sense voltage.

  14. Solution structure and phospholipid interactions of the isolated voltage-sensor domain from KvAP.

    Science.gov (United States)

    Butterwick, Joel A; MacKinnon, Roderick

    2010-11-05

    Voltage-sensor domains (VSDs) are specialized transmembrane segments that confer voltage sensitivity to many proteins such as ion channels and enzymes. The activities of these domains are highly dependent on both the chemical properties and the physical properties of the surrounding membrane environment. To learn about VSD-lipid interactions, we used nuclear magnetic resonance spectroscopy to determine the structure and phospholipid interface of the VSD from the voltage-dependent K(+) channel KvAP (prokaryotic Kv from Aeropyrum pernix). The solution structure of the KvAP VSD solubilized within phospholipid micelles is similar to a previously determined crystal structure solubilized by a nonionic detergent and complexed with an antibody fragment. The differences observed include a previously unidentified short amphipathic α-helix that precedes the first transmembrane helix and a subtle rigid-body repositioning of the S3-S4 voltage-sensor paddle. Using (15)N relaxation experiments, we show that much of the VSD, including the pronounced kink in S3 and the S3-S4 paddle, is relatively rigid on the picosecond-to-nanosecond timescale. In contrast, the kink in S3 is mobile on the microsecond-to-millisecond timescale and may act as a hinge in the movement of the paddle during channel gating. We characterized the VSD-phospholipid micelle interactions using nuclear Overhauser effect spectroscopy and showed that the micelle uniformly coats the KvAP VSD and approximates the chemical environment of a phospholipid bilayer. Using paramagnetically labeled phospholipids, we show that bilayer-forming lipids interact with the S3 and S4 helices more strongly than with S1 and S2.

  15. Mapping of voltage sensor positions in resting and inactivated mammalian sodium channels by LRET.

    Science.gov (United States)

    Kubota, Tomoya; Durek, Thomas; Dang, Bobo; Finol-Urdaneta, Rocio K; Craik, David J; Kent, Stephen B H; French, Robert J; Bezanilla, Francisco; Correa, Ana M

    2017-03-07

    Voltage-gated sodium channels (Navs) play crucial roles in excitable cells. Although vertebrate Nav function has been extensively studied, the detailed structural basis for voltage-dependent gating mechanisms remain obscure. We have assessed the structural changes of the Nav voltage sensor domain using lanthanide-based resonance energy transfer (LRET) between the rat skeletal muscle voltage-gated sodium channel (Nav1.4) and fluorescently labeled Nav1.4-targeting toxins. We generated donor constructs with genetically encoded lanthanide-binding tags (LBTs) inserted at the extracellular end of the S4 segment of each domain (with a single LBT per construct). Three different Bodipy-labeled, Nav1.4-targeting toxins were synthesized as acceptors: β-scorpion toxin (Ts1)-Bodipy, KIIIA-Bodipy, and GIIIA-Bodipy analogs. Functional Nav-LBT channels expressed in Xenopus oocytes were voltage-clamped, and distinct LRET signals were obtained in the resting and slow inactivated states. Intramolecular distances computed from the LRET signals define a geometrical map of Nav1.4 with the bound toxins, and reveal voltage-dependent structural changes related to channel gating.

  16. Mapping of voltage sensor positions in resting and inactivated mammalian sodium channels by LRET

    Science.gov (United States)

    Kubota, Tomoya; Durek, Thomas; Dang, Bobo; Finol-Urdaneta, Rocio K.; Craik, David J.; Kent, Stephen B. H.; French, Robert J.; Bezanilla, Francisco; Correa, Ana M.

    2017-01-01

    Voltage-gated sodium channels (Navs) play crucial roles in excitable cells. Although vertebrate Nav function has been extensively studied, the detailed structural basis for voltage-dependent gating mechanisms remain obscure. We have assessed the structural changes of the Nav voltage sensor domain using lanthanide-based resonance energy transfer (LRET) between the rat skeletal muscle voltage-gated sodium channel (Nav1.4) and fluorescently labeled Nav1.4-targeting toxins. We generated donor constructs with genetically encoded lanthanide-binding tags (LBTs) inserted at the extracellular end of the S4 segment of each domain (with a single LBT per construct). Three different Bodipy-labeled, Nav1.4-targeting toxins were synthesized as acceptors: β-scorpion toxin (Ts1)-Bodipy, KIIIA-Bodipy, and GIIIA-Bodipy analogs. Functional Nav-LBT channels expressed in Xenopus oocytes were voltage-clamped, and distinct LRET signals were obtained in the resting and slow inactivated states. Intramolecular distances computed from the LRET signals define a geometrical map of Nav1.4 with the bound toxins, and reveal voltage-dependent structural changes related to channel gating. PMID:28202723

  17. Determination of the aging offset voltage of AMR sensors based on accelerated degradation test

    NARCIS (Netherlands)

    Zambrano, Andreina; Kerkhoff, Hans G.

    2015-01-01

    Usually Anisotropic Magnetoresistance angle sensors are configured with two Wheatstone bridges, but an undesirable offset voltage included in the sensor output affects its accuracy. The total offset voltage combines a voltage due to resistance mismatches during manufacturing and a voltage from inequ

  18. Ozone Sensor for Application in Medium Voltage Switchboard

    Directory of Open Access Journals (Sweden)

    Letizia De Maria

    2009-01-01

    Full Text Available The application of a new spectroscopic type fiber sensor for ozone detection in electrical components of Medium Voltage (MV network is evaluated. The sensor layout is based on the use of an optical retroreflector, to improve the detection sensitivity, and it was especially designed for detecting in situ rapid changes of ozone concentration. Preliminary tests were performed in a typical MV switchboard. Artificial defects simulated predischarge phenomena arising during real operating conditions. Results are discussed by a comparison with data simultaneously acquired with a standard partial discharge system.

  19. 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...

  20. Voltage dependence of Hodgkin-Huxley rate functions for a multistage K^{+} channel voltage sensor within a membrane.

    Science.gov (United States)

    Vaccaro, S R

    2014-11-01

    The activation of a K^{+} channel sensor in two sequential stages during a voltage clamp may be described as the translocation of a Brownian particle in an energy landscape with two large barriers between states. A solution of the Smoluchowski equation for a square-well approximation to the potential function of the S4 voltage sensor satisfies a master equation and has two frequencies that may be determined from the forward and backward rate functions. When the higher-frequency terms have small amplitude, the solution reduces to the relaxation of a rate equation, where the derived two-state rate functions are dependent on the relative magnitude of the forward rates (α and γ) and the backward rates (β and δ) for each stage. In particular, the voltage dependence of the Hodgkin-Huxley rate functions for a K^{+} channel may be derived by assuming that the rate functions of the first stage are large relative to those of the second stage-α≫γ and β≫δ. For a Shaker IR K^{+} channel, the first forward and backward transitions are rate limiting (αchannel and a noninactivating Na^{+} ion channel is determined by the master equation for K^{+} channel activation and the ionic current equation when the Na^{+} channel activation time is small, and if β≪δ and α≪γ, the system may exhibit a small amplitude oscillation between spikes, or mixed-mode oscillation, in which the slow closed state modulates the K^{+} ion channel conductance in the membrane.

  1. A vesicle-trafficking protein commandeers Kv channel voltage sensors for voltage-dependent secretion.

    Science.gov (United States)

    Grefen, Christopher; Karnik, Rucha; Larson, Emily; Lefoulon, Cécile; Wang, Yizhou; Waghmare, Sakharam; Zhang, Ben; Hills, Adrian; Blatt, Michael R

    2015-01-01

    Growth in plants depends on ion transport for osmotic solute uptake and secretory membrane trafficking to deliver material for wall remodelling and cell expansion. The coordination of these processes lies at the heart of the question, unresolved for more than a century, of how plants regulate cell volume and turgor. Here we report that the SNARE protein SYP121 (SYR1/PEN1), which mediates vesicle fusion at the Arabidopsis plasma membrane, binds the voltage sensor domains (VSDs) of K(+) channels to confer a voltage dependence on secretory traffic in parallel with K(+) uptake. VSD binding enhances secretion in vivo subject to voltage, and mutations affecting VSD conformation alter binding and secretion in parallel with channel gating, net K(+) concentration, osmotic content and growth. These results demonstrate a new and unexpected mechanism for secretory control, in which a subset of plant SNAREs commandeer K(+) channel VSDs to coordinate membrane trafficking with K(+) uptake for growth.

  2. Design and Simulation Test of an Open D-Dot Voltage Sensor

    Directory of Open Access Journals (Sweden)

    Yunjie Bai

    2015-09-01

    Full Text Available Nowadays, sensor development focuses on miniaturization and non-contact measurement. According to the D-dot principle, a D-dot voltage sensor with a new structure was designed based on the differential D-dot sensor with a symmetrical structure, called an asymmetric open D-dot voltage sensor. It is easier to install. The electric field distribution of the sensor was analyzed through Ansoft Maxwell and an open D-dot voltage sensor was designed. This open D-voltage sensor is characteristic of accessible insulating strength and small electric field distortion. The steady and transient performance test under 10 kV-voltage reported satisfying performances of the designed open D-dot voltage sensor. It conforms to requirements for a smart grid measuring sensor in intelligence, miniaturization and facilitation.

  3. Voltage-dependent gating of hyperpolarization-activated, cyclic nucleotide-gated pacemaker channels: molecular coupling between the S4-S5 and C-linkers.

    Science.gov (United States)

    Decher, Niels; Chen, Jun; Sanguinetti, Michael C

    2004-04-02

    Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels have a transmembrane topology that is highly similar to voltage-gated K(+) channels, yet HCN channels open in response to membrane hyperpolarization instead of depolarization. The structural basis for the "inverted" voltage dependence of HCN gating and how voltage sensing by the S1-S4 domains is coupled to the opening of the intracellular gate formed by the S6 domain are unknown. Coupling could arise from interaction between specific residues or entire transmembrane domains. We previously reported that the mutation of specific residues in the S4-S5 linker of HCN2 (i.e. Tyr-331 and Arg-339) prevented normal channel closure presumably by disruption of a crucial interaction with the activation gate. Here we hypothesized that the C-linker, a carboxyl terminus segment that connects S6 to the cyclic nucleotide binding domain, interacts with specific residues of the S4-S5 linker to mediate coupling. The recently solved structure of the C-linker of HCN2 indicates that an alpha-helix (the A'-helix) is located near the end of each S6 domain, the presumed location of the activation gate. Ala-scanning mutagenesis of the end of S6 and the A'-helix identified five residues that were important for normal gating as mutations disrupted channel closure. However, partial deletion of the C-linker indicated that the presence of only two of these residues was required for normal coupling. Further mutation analyses suggested that a specific electrostatic interaction between Arg-339 of the S4-S5 linker and Asp-443 of the C-linker stabilizes the closed state and thus participates in the coupling of voltage sensing and activation gating in HCN channels.

  4. A novel voltage output integrated circuit temperature sensor

    Institute of Scientific and Technical Information of China (English)

    吴晓波; 方志刚; 等

    2002-01-01

    The novel integrated circuit(IC) temperature sensor presented in this paper works similarly as a two-terminal Zener,has breakdown voltage directly proportional to Kelvin temperature at 10mV/℃,with typical error of less tha ±1.0℃ over a temperature range from-50℃to +120℃ .In addition to all the features that conventional IC temperature sensors have,the new device also has very low static power dissipation(0.5mW),low output impedance(less than 1Ω),execllent stability,high reproducibility,and high precision.The sensor's circuit design and layout are discussed in detail.Applications of the sensor include almost and type of temperature sensing over the range of -50℃-+125℃。The low impedance and linear output of the device make interfacing the readout or control circuitry especially easy.Due to the excellent performance and low cost of this sensor.more application of the sensor over wide temperature range are expected.

  5. A novel voltage output integrated circuit temperature sensor

    Institute of Scientific and Technical Information of China (English)

    吴晓波; 赵梦恋; 严晓浪; 方志刚

    2002-01-01

    The novel integrated circuit (IC) temperature sensor presented in this paper works similarly as a two-terminal Zener, has breakdown voltage directly proportional to Kelvin temperature at 10 mV/℃, with typical error of less than ±1.0℃ over a temperature range from -50℃ to +125℃. In addition to all the features that conventional IC temperature sensors have, the new device also has very low static power dissipation ( 0.5 mW ) , low output impedance ( less than 1Ω), excellent stability, high reproducibility, and high precision. The sensor's circuit design and layout are discussed in detail. Applications of the sensor include almost any type of temperature sensing over the range of -50℃-+125℃. The low impedance and linear output of the device make interfacing the readout or control circuitry especially easy. Due to the excellent performance and low cost of this sensor, more applications of the sensor over wide temperature range are expected.

  6. Polarity-dependent conformational switching of a peptide mimicking the S4-S5 linker of the voltage-sensitive sodium channel.

    Science.gov (United States)

    Helluin, O; Breed, J; Duclohier, H

    1996-02-21

    The S4-S5 linker (or S45) in voltage-sensitive sodium channels was previously shown to be involved in the permeation pathway. The secondary structure, investigated by circular dichroism, of a S4-S45 peptide from domain IV and its fragments (including S45) is reported here and compared with that of the homologous peptide from domain II as a function of the solvent dielectric constant. The reduction in helicity seen for S4-S45 (II) in polar media is cancelled in membrane-like environment. The most striking result-- a sharp alpha-helix --> beta-sheet transition upon exposure of the S45 moiety to aqueous solvents-- is discussed as regards channel activation and selectivity.

  7. Direct evidence that scorpion α-toxins (site-3 modulate sodium channel inactivation by hindrance of voltage-sensor movements.

    Directory of Open Access Journals (Sweden)

    Zhongming Ma

    Full Text Available The position of the voltage-sensing transmembrane segment, S4, in voltage-gated ion channels as a function of voltage remains incompletely elucidated. Site-3 toxins bind primarily to the extracellular loops connecting transmembrane helical segments S1-S2 and S3-S4 in Domain 4 (D4 and S5-S6 in Domain 1 (D1 and slow fast-inactivation of voltage-gated sodium channels. As S4 of the human skeletal muscle voltage-gated sodium channel, hNav1.4, moves in response to depolarization from the resting to the inactivated state, two D4S4 reporters (R2C and R3C, Arg1451Cys and Arg1454Cys, respectively move from internal to external positions as deduced by reactivity to internally or externally applied sulfhydryl group reagents, methane thiosulfonates (MTS. The changes in reporter reactivity, when cycling rapidly between hyperpolarized and depolarized voltages, enabled determination of the positions of the D4 voltage-sensor and of its rate of movement. Scorpion α-toxin binding impedes D4S4 segment movement during inactivation since the modification rates of R3C in hNav1.4 with methanethiosulfonate (CH3SO2SCH2CH2R, where R = -N(CH33 (+ trimethylammonium, MTSET and benzophenone-4-carboxamidocysteine methanethiosulfonate (BPMTS were slowed ~10-fold in toxin-modified channels. Based upon the different size, hydrophobicity and charge of the two reagents it is unlikely that the change in reactivity is due to direct or indirect blockage of access of this site to reagent in the presence of toxin (Tx, but rather is the result of inability of this segment to move outward to the normal extent and at the normal rate in the toxin-modified channel. Measurements of availability of R3C to internally applied reagent show decreased access (slower rates of thiol reaction providing further evidence for encumbered D4S4 movement in the presence of toxins consistent with the assignment of at least part of the toxin binding site to the region of D4S4 region of the voltage-sensor

  8. Binding of Hanatoxin to the Voltage Sensor of Kv2.1

    Directory of Open Access Journals (Sweden)

    Shin-Ho Chung

    2012-12-01

    Full Text Available Hanatoxin 1 (HaTx1 is a polypeptide toxin isolated from spider venoms. HaTx1 inhibits the voltage-gated potassium channel kv2.1 potently with nanomolar affinities. Its receptor site has been shown to contain the S3b-S4a paddle of the voltage sensor (VS. Here, the binding of HaTx1 to the VSs of human Kv2.1 in the open and resting states are examined using a molecular docking method and molecular dynamics. Molecular docking calculations predict two distinct binding modes for the VS in the resting state. In the two binding modes, the toxin binds the S3b-S4a from S2 and S3 helices, or from S1 and S4 helices. Both modes are found to be stable when embedded in a lipid bilayer. Only the mode in which the toxin binds the S3b-S4a paddle from S2 and S3 helices is consistent with mutagenesis experiments, and considered to be correct. The toxin is then docked to the VS in the open state, and the toxin-VS interactions are found to be less favorable. Computational mutagenesis calculations performed on F278R and E281K mutant VSs show that the mutations may reduce toxin binding affinity by weakening the non-bonded interactions between the toxin and the VS. Overall, our calculations reproduce a wide range of experimental data, and suggest that HaTx1 binds to the S3b-S4a paddle of Kv2.1 from S2 and S3 helices.

  9. Combinatorial mutagenesis of the voltage-sensing domain enables the optical resolution of action potentials firing at 60 Hz by a genetically encoded fluorescent sensor of membrane potential.

    Science.gov (United States)

    Piao, Hong Hua; Rajakumar, Dhanarajan; Kang, Bok Eum; Kim, Eun Ha; Baker, Bradley J

    2015-01-07

    ArcLight is a genetically encoded fluorescent voltage sensor using the voltage-sensing domain of the voltage-sensing phosphatase from Ciona intestinalis that gives a large but slow-responding optical signal in response to changes in membrane potential (Jin et al., 2012). Fluorescent voltage sensors using the voltage-sensing domain from other species give faster yet weaker optical signals (Baker et al., 2012; Han et al., 2013). Sequence alignment of voltage-sensing phosphatases from different species revealed conserved polar and charged residues at 7 aa intervals in the S1-S3 transmembrane segments of the voltage-sensing domain, suggesting potential coil-coil interactions. The contribution of these residues to the voltage-induced optical signal was tested using a cassette mutagenesis screen by flanking each transmembrane segment with unique restriction sites to allow for the testing of individual mutations in each transmembrane segment, as well as combinations in all four transmembrane segments. Addition of a counter charge in S2 improved the kinetics of the optical response. A double mutation in the S4 domain dramatically reduced the slow component of the optical signal seen in ArcLight. Combining that double S4 mutant with the mutation in the S2 domain yielded a probe with kinetics voltage-sensing domain could potentially lead to fluorescent sensors capable of optically resolving neuronal inhibition and subthreshold synaptic activity.

  10. An automatic method to analyze the Capacity-Voltage and Current-Voltage curves of a sensor

    CERN Document Server

    Matorras Cuevas, Pablo

    2017-01-01

    An automatic method to perform Capacity versus voltage analysis for all kind of silicon sensor is provided. It successfully calculates the depletion voltage to unirradiated and irradiated sensors, and with measurements with outliers or reaching breakdown. It is built using C++ and using ROOT trees with an analogous skeleton as TRICS, where the data as well as the results of the ts are saved, to make further analysis.

  11. Analysis and Improvement of Reflection-type Transverse Modulation Optical Voltage Sensors

    Institute of Scientific and Technical Information of China (English)

    LUO Sunan; YE Miaoyuan; XU Yan; CUI Ying

    2001-01-01

    Reflection-type transverse modulation optical voltage sensors, which employ reflection retarders to replace quarter-wave plates, are convenient for practical use. In previous literatures, the measured voltage was all applied to Bi4Ge3O12 crystal along the (110) direction for transverse modulation optical voltage sensor, and crystals are used as sensing materials. In this paper, reflection-type transverse modulation optical voltage sensor has been analyzed theoretically and a novel configuration in which the measured voltage is applied to a Bi4C-e3O12 crystal along the (001) direction with light wave passing through the crystal in the (110) direction has been proposed. According to this theoretical analysis, a novel optical voltage sensor, which can be used in a 220 kV optical fiber voltage transformer, has been designed and assembled. Experimental results showed that the linearity and the stability of the sensor during 24 hours can reach 0.3%.

  12. Deletion of cytosolic gating ring decreases gate and voltage sensor coupling in BK channels.

    Science.gov (United States)

    Zhang, Guohui; Geng, Yanyan; Jin, Yakang; Shi, Jingyi; McFarland, Kelli; Magleby, Karl L; Salkoff, Lawrence; Cui, Jianmin

    2017-03-06

    Large conductance Ca(2+)-activated K(+) channels (BK channels) gate open in response to both membrane voltage and intracellular Ca(2+) The channel is formed by a central pore-gate domain (PGD), which spans the membrane, plus transmembrane voltage sensors and a cytoplasmic gating ring that acts as a Ca(2+) sensor. How these voltage and Ca(2+) sensors influence the common activation gate, and interact with each other, is unclear. A previous study showed that a BK channel core lacking the entire cytoplasmic gating ring (Core-MT) was devoid of Ca(2+) activation but retained voltage sensitivity (Budelli et al. 2013. Proc. Natl. Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1313433110). In this study, we measure voltage sensor activation and pore opening in this Core-MT channel over a wide range of voltages. We record gating currents and find that voltage sensor activation in this truncated channel is similar to WT but that the coupling between voltage sensor activation and gating of the pore is reduced. These results suggest that the gating ring, in addition to being the Ca(2+) sensor, enhances the effective coupling between voltage sensors and the PGD. We also find that removal of the gating ring alters modulation of the channels by the BK channel's β1 and β2 subunits.

  13. Contributions of counter-charge in a potassium channel voltage-sensor domain

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Galpin, Jason D; Niciforovic, Ana P

    2011-01-01

    Voltage-sensor domains couple membrane potential to conformational changes in voltage-gated ion channels and phosphatases. Highly coevolved acidic and aromatic side chains assist the transfer of cationic side chains across the transmembrane electric field during voltage sensing. We investigated...

  14. Non-contact current and voltage sensor having detachable housing incorporating multiple ferrite cylinder portions

    Science.gov (United States)

    Carpenter, Gary D.; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C.; Schappert, Michael A.

    2016-04-26

    A detachable current and voltage sensor provides an isolated and convenient device to measure current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing formed from two portions that mechanically close around the wire and that contain the current and voltage sensors. The current sensor is a ferrite cylinder formed from at least three portions that form the cylinder when the sensor is closed around the wire with a hall effect sensor disposed in a gap between two of the ferrite portions along the circumference to measure current. A capacitive plate or wire is disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

  15. The free energy barrier for arginine gating charge translation is altered by mutations in the voltage sensor domain.

    Directory of Open Access Journals (Sweden)

    Christine S Schwaiger

    Full Text Available The gating of voltage-gated ion channels is controlled by the arginine-rich S4 helix of the voltage-sensor domain moving in response to an external potential. Recent studies have suggested that S4 moves in three to four steps to open the conducting pore, thus visiting several intermediate conformations during gating. However, the exact conformational changes are not known in detail. For instance, it has been suggested that there is a local rotation in the helix corresponding to short segments of a 3(10-helix moving along S4 during opening and closing. Here, we have explored the energetics of the transition between the fully open state (based on the X-ray structure and the first intermediate state towards channel closing (C1, modeled from experimental constraints. We show that conformations within 3 Å of the X-ray structure are obtained in simulations starting from the C1 model, and directly observe the previously suggested sliding 3(10-helix region in S4. Through systematic free energy calculations, we show that the C1 state is a stable intermediate conformation and determine free energy profiles for moving between the states without constraints. Mutations indicate several residues in a narrow hydrophobic band in the voltage sensor contribute to the barrier between the open and C1 states, with F233 in the S2 helix having the largest influence. Substitution for smaller amino acids reduces the transition cost, while introduction of a larger ring increases it, largely confirming experimental activation shift results. There is a systematic correlation between the local aromatic ring rotation, the arginine barrier crossing, and the corresponding relative free energy. In particular, it appears to be more advantageous for the F233 side chain to rotate towards the extracellular side when arginines cross the hydrophobic region.

  16. Study and Experiment on Non-Contact Voltage Sensor Suitable for Three-Phase Transmission Line.

    Science.gov (United States)

    Zhou, Qiang; He, Wei; Xiao, Dongping; Li, Songnong; Zhou, Kongjun

    2015-12-30

    A voltage transformer, as voltage signal detection equipment, plays an important role in a power system. Presently, more and more electric power systems are adopting potential transformer and capacitance voltage transformers. Transformers are often large in volume and heavyweight, their insulation design is difficult, and an iron core or multi-grade capacitance voltage division structure is generally adopted. As a result, the detection accuracy of transformer is reduced, a huge phase difference exists between detection signal and voltage signal to be measured, and the detection signal cannot accurately and timely reflect the change of conductor voltage signal to be measured. By aiming at the current problems of electric transformation, based on electrostatic induction principle, this paper designed a non-contact voltage sensor and gained detection signal of the sensor through electrostatic coupling for the electric field generated by electric charges of the conductor to be measured. The insulation structure design of the sensor is simple and its volume is small; phase difference of sensor measurement is effectively reduced through optimization design of the electrode; and voltage division ratio and measurement accuracy are increased. The voltage sensor was tested on the experimental platform of simulating three-phase transmission line. According to the result, the designed non-contact voltage sensor can realize accurate and real-time measurement for the conductor voltage. It can be applied to online monitoring for the voltage of three-phase transmission line or three-phase distribution network line, which is in accordance with the development direction of the smart grid.

  17. Study and Experiment on Non-Contact Voltage Sensor Suitable for Three-Phase Transmission Line

    Directory of Open Access Journals (Sweden)

    Qiang Zhou

    2015-12-01

    Full Text Available A voltage transformer, as voltage signal detection equipment, plays an important role in a power system. Presently, more and more electric power systems are adopting potential transformer and capacitance voltage transformers. Transformers are often large in volume and heavyweight, their insulation design is difficult, and an iron core or multi-grade capacitance voltage division structure is generally adopted. As a result, the detection accuracy of transformer is reduced, a huge phase difference exists between detection signal and voltage signal to be measured, and the detection signal cannot accurately and timely reflect the change of conductor voltage signal to be measured. By aiming at the current problems of electric transformation, based on electrostatic induction principle, this paper designed a non-contact voltage sensor and gained detection signal of the sensor through electrostatic coupling for the electric field generated by electric charges of the conductor to be measured. The insulation structure design of the sensor is simple and its volume is small; phase difference of sensor measurement is effectively reduced through optimization design of the electrode; and voltage division ratio and measurement accuracy are increased. The voltage sensor was tested on the experimental platform of simulating three-phase transmission line. According to the result, the designed non-contact voltage sensor can realize accurate and real-time measurement for the conductor voltage. It can be applied to online monitoring for the voltage of three-phase transmission line or three-phase distribution network line, which is in accordance with the development direction of the smart grid.

  18. A membrane-access mechanism of ion channel inhibition by voltage sensor toxins from spider venom

    Science.gov (United States)

    Lee, Seok-Yong; MacKinnon, Roderick

    2004-07-01

    Venomous animals produce small protein toxins that inhibit ion channels with high affinity. In several well-studied cases the inhibitory proteins are water-soluble and bind at a channel's aqueous-exposed extracellular surface. Here we show that a voltage-sensor toxin (VSTX1) from the Chilean Rose Tarantula (Grammostola spatulata) reaches its target by partitioning into the lipid membrane. Lipid membrane partitioning serves two purposes: to localize the toxin in the membrane where the voltage sensor resides and to exploit the free energy of partitioning to achieve apparent high-affinity inhibition. VSTX1, small hydrophobic poisons and anaesthetic molecules reveal a common theme of voltage sensor inhibition through lipid membrane access. The apparent requirement for such access is consistent with the recent proposal that the sensor in voltage-dependent K+ channels is located at the membrane-protein interface.

  19. Results of the 2015 testbeam of a 180 nm AMS High-Voltage CMOS sensor prototype

    CERN Document Server

    Benoit, M; de Mendizabal, J. Bilbao; Chen, H; Chen, K; Di Bello, F.A; Ferrere, D; Golling, T; Gonzalez-Sevilla, S; Iacobucci, G; Lanni, F; Liu, H; Meng, L; Miucci, A; Muenstermann, D; Nessi, M; Peric, I; Rimoldi, M; Ristic, B; Pinto, M. Vicente Barrero; Vossebeld, J; Weber, M; Wu, W; Xu, L

    2016-01-01

    Active pixel sensors based on the High-Voltage CMOS technology are being investigated as a viable option for the future pixel tracker of the ATLAS experiment at the High-Luminosity LHC. This paper reports on the testbeam measurements performed at the H8 beamline of the CERN Super Proton Synchrotron on a High-Voltage CMOS sensor prototype produced in 180 nm AMS technology. Results in terms of tracking efficiency and timing performance, for different threshold and bias conditions, are shown.

  20. S1-S3 counter charges in the voltage sensor module of a mammalian sodium channel regulate fast inactivation.

    Science.gov (United States)

    Groome, James R; Winston, Vern

    2013-05-01

    The movement of positively charged S4 segments through the electric field drives the voltage-dependent gating of ion channels. Studies of prokaryotic sodium channels provide a mechanistic view of activation facilitated by electrostatic interactions of negatively charged residues in S1 and S2 segments, with positive counterparts in the S4 segment. In mammalian sodium channels, S4 segments promote domain-specific functions that include activation and several forms of inactivation. We tested the idea that S1-S3 countercharges regulate eukaryotic sodium channel functions, including fast inactivation. Using structural data provided by bacterial channels, we constructed homology models of the S1-S4 voltage sensor module (VSM) for each domain of the mammalian skeletal muscle sodium channel hNaV1.4. These show that side chains of putative countercharges in hNaV1.4 are oriented toward the positive charge complement of S4. We used mutagenesis to define the roles of conserved residues in the extracellular negative charge cluster (ENC), hydrophobic charge region (HCR), and intracellular negative charge cluster (INC). Activation was inhibited with charge-reversing VSM mutations in domains I-III. Charge reversal of ENC residues in domains III (E1051R, D1069K) and IV (E1373K, N1389K) destabilized fast inactivation by decreasing its probability, slowing entry, and accelerating recovery. Several INC mutations increased inactivation from closed states and slowed recovery. Our results extend the functional characterization of VSM countercharges to fast inactivation, and support the premise that these residues play a critical role in domain-specific gating transitions for a mammalian sodium channel.

  1. A distinct sodium channel voltage-sensor locus determines insect selectivity of the spider toxin Dc1a

    Science.gov (United States)

    Bende, Niraj S.; Dziemborowicz, Sławomir; Mobli, Mehdi; Herzig, Volker; Gilchrist, John; Wagner, Jordan; Nicholson, Graham M.; King, Glenn F.; Bosmans, Frank

    2014-07-01

    β-Diguetoxin-Dc1a (Dc1a) is a toxin from the desert bush spider Diguetia canities that incapacitates insects at concentrations that are non-toxic to mammals. Dc1a promotes opening of German cockroach voltage-gated sodium (Nav) channels (BgNav1), whereas human Nav channels are insensitive. Here, by transplanting commonly targeted S3b-S4 paddle motifs within BgNav1 voltage sensors into Kv2.1, we find that Dc1a interacts with the domain II voltage sensor. In contrast, Dc1a has little effect on sodium currents mediated by PaNav1 channels from the American cockroach even though their domain II paddle motifs are identical. When exploring regions responsible for PaNav1 resistance to Dc1a, we identified two residues within the BgNav1 domain II S1-S2 loop that when mutated to their PaNav1 counterparts drastically reduce toxin susceptibility. Overall, our results reveal a distinct region within insect Nav channels that helps determine Dc1a sensitivity, a concept that will be valuable for the design of insect-selective insecticides.

  2. Modeling of a Silicon Nanowire pH Sensor with Nanoscale Side Gate Voltage

    Institute of Scientific and Technical Information of China (English)

    Alireza Kargar

    2009-01-01

    A silicon nanowire (Si-NW) sensor for pH detection is presented.The conductance of the device is analytically obtained,demonstrating that the conductance increases with decreasing oxide thickness.To calculate the electrical conductance of the sensor,the diffusion-drift model and nonlinear Poisson-Boltzmann equation are applied.To improve the conductance and sensitivity,a Si-NW sensor with nanoscale side gate voltage is offered and its characteristics are theoretically achieved.It is revealed that the conductance and sensor sensitivity can be enhanced by adding appropriate side gate voltages.This effect is compared to a similar fabricated structure in the literature,which has a wire with a rectangular cross section.Finally,the effect of NW length on sensor performance is investigated and an inverse relation between sensor sensitivity and NW length is achieved.

  3. Independent movement of the voltage sensors in KV2.1/KV6.4 heterotetramers.

    Science.gov (United States)

    Bocksteins, Elke; Snyders, Dirk J; Holmgren, Miguel

    2017-01-31

    Heterotetramer voltage-gated K(+) (KV) channels KV2.1/KV6.4 display a gating charge-voltage (QV) distribution composed by two separate components. We use state dependent chemical accessibility to cysteines substituted in either KV2.1 or KV6.4 to assess the voltage sensor movements of each subunit. By comparing the voltage dependences of chemical modification and gating charge displacement, here we show that each gating charge component corresponds to a specific subunit forming the heterotetramer. The voltage sensors from KV6.4 subunits move at more negative potentials than the voltage sensors belonging to KV2.1 subunits. These results indicate that the voltage sensors from the tetrameric channels move independently. In addition, our data shows that 75% of the total charge is attributed to KV2.1, while 25% to KV6.4. Thus, the most parsimonious model for KV2.1/KV6.4 channels' stoichiometry is 3:1.

  4. Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal, E-mail: zainabh@petronas.com.my [Centre of Innovative Nanostructures and Nanodevices, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2014-03-24

    Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

  5. Optical fiber sensor of partial discharges in High Voltage DC experiments

    Science.gov (United States)

    Búa-Núñez, I.; Azcárraga-Ramos, C. G.; Posada-Román, J. E.; Garcia-Souto, J. A.

    2014-05-01

    A setup simulating High Voltage DC (HVDC) transformers barriers was developed to demonstrate the effectiveness of an optical fiber (OF) sensor in detecting partial discharges (PD) under these peculiar conditions. Different PD detection techniques were compared: electrical methods, and acoustic methods. Standard piezoelectric sensors (R15i-AST) and the above mentioned OF sensors were used for acoustic detection. The OF sensor was able to detect PD acoustically with a sensitivity better than the other detection methods. The multichannel instrumentation system was tested in real HVDC conditions with the aim of analyzing the behavior of the insulation (mineral oil/pressboard).

  6. High Voltage Coil Current Sensor for DC-DC Converters Employing DDCC

    Directory of Open Access Journals (Sweden)

    M. Drinovsky

    2015-12-01

    Full Text Available Current sensor is an integral part of every switching converter. It is used for over-current protection, regulation and in case of multiphase converters for balancing. A new high voltage current sensor for coil-based current sensing in DC-DC converters is presented. The sensor employs DDCC with high voltage input stage and gain trimming. The circuit has been simulated and implemented in 0.35 um BCD technology as part of a multiphase DC-DC converter where its function has been verified. The circuit is able to sustain common mode voltage on the input up to 40 V, it occupies 0.387*0.345 mm2 and consumes 3.2 mW typically.

  7. KCNE1 divides the voltage sensor movement in KCNQ1/KCNE1 channels into two steps

    Science.gov (United States)

    Barro-Soria, Rene; Rebolledo, Santiago; Liin, Sara I.; Perez, Marta E.; Sampson, Kevin J.; Kass, Robert S.; Larsson, H. Peter

    2014-04-01

    The functional properties of KCNQ1 channels are highly dependent on associated KCNE-β subunits. Mutations in KCNQ1 or KCNE subunits can cause congenital channelopathies, such as deafness, cardiac arrhythmias and epilepsy. The mechanism by which KCNE1-β subunits slow the kinetics of KCNQ1 channels is a matter of current controversy. Here we show that KCNQ1/KCNE1 channel activation occurs in two steps: first, mutually independent voltage sensor movements in the four KCNQ1 subunits generate the main gating charge movement and underlie the initial delay in the activation time course of KCNQ1/KCNE1 currents. Second, a slower and concerted conformational change of all four voltage sensors and the gate, which opens the KCNQ1/KCNE1 channel. Our data show that KCNE1 divides the voltage sensor movement into two steps with widely different voltage dependences and kinetics. The two voltage sensor steps in KCNQ1/KCNE1 channels can be pharmacologically isolated and further separated by a disease-causing mutation.

  8. Investigation of leakage current and breakdown voltage in irradiated double-sided 3D silicon sensors

    Science.gov (United States)

    Dalla Betta, G.-F.; Ayllon, N.; Boscardin, M.; Hoeferkamp, M.; Mattiazzo, S.; McDuff, H.; Mendicino, R.; Povoli, M.; Seidel, S.; Sultan, D. M. S.; Zorzi, N.

    2016-09-01

    We report on an experimental study aimed at gaining deeper insight into the leakage current and breakdown voltage of irradiated double-sided 3D silicon sensors from FBK, so as to improve both the design and the fabrication technology for use at future hadron colliders such as the High Luminosity LHC. Several 3D diode samples of different technologies and layout are considered, as well as several irradiations with different particle types. While the leakage current follows the expected linear trend with radiation fluence, the breakdown voltage is found to depend on both the bulk damage and the surface damage, and its values can vary significantly with sensor geometry and process details.

  9. Bio-Inspired Carbon Monoxide Sensors with Voltage-Activated Sensitivity

    KAUST Repository

    Savagatrup, Suchol

    2017-09-27

    Carbon monoxide (CO) outcompetes oxygen when binding to the iron center of hemeproteins, leading to a reduction in blood oxygen level and acute poisoning. Harvesting the strong specific interaction between CO and the iron porphyrin provides a highly selective and customizable sensor. We report the development of chemiresistive sensors with voltage-activated sensitivity for the detection of CO comprising iron porphyrin and functionalized single-walled carbon nanotubes (F-SWCNTs). Modulation of the gate voltage offers a predicted extra dimension for sensing. Specifically, the sensors show a significant increase in sensitivity toward CO when negative gate voltage is applied. The dosimetric sensors are selective to ppm levels of CO and functional in air. UV/Vis spectroscopy, differential pulse voltammetry, and density functional theory reveal that the in situ reduction of FeIII to FeII enhances the interaction between the F-SWCNTs and CO. Our results illustrate a new mode of sensors wherein redox active recognition units are voltage-activated to give enhanced and highly specific responses.

  10. A Fiber-Optic Sensor for Acoustic Emission Detection in a High Voltage Cable System

    Directory of Open Access Journals (Sweden)

    Tongzhi Zhang

    2016-11-01

    Full Text Available We have proposed and demonstrated a Michelson interferometer-based fiber sensor for detecting acoustic emission generated from the partial discharge (PD of the accessories of a high-voltage cable system. The developed sensor head is integrated with a compact and relatively high sensitivity cylindrical elastomer. Such a sensor has a broadband frequency response and a relatively high sensitivity in a harsh environment under a high-voltage electric field. The design and fabrication of the sensor head integrated with the cylindrical elastomer is described, and a series of experiments was conducted to evaluate the sensing performance. The experimental results demonstrate that the sensitivity of our developed sensor for acoustic detection of partial discharges is 1.7 rad / ( m ⋅ Pa . A high frequency response up to 150 kHz is achieved. Moreover, the relatively high sensitivity for the detection of PD is verified in both the laboratory environment and gas insulated switchgear. The obtained results show the great potential application of a Michelson interferometer-based fiber sensor integrated with a cylindrical elastomer for in-situ monitoring high-voltage cable accessories for safety work.

  11. A Fiber-Optic Sensor for Acoustic Emission Detection in a High Voltage Cable System.

    Science.gov (United States)

    Zhang, Tongzhi; Pang, Fufei; Liu, Huanhuan; Cheng, Jiajing; Lv, Longbao; Zhang, Xiaobei; Chen, Na; Wang, Tingyun

    2016-11-30

    We have proposed and demonstrated a Michelson interferometer-based fiber sensor for detecting acoustic emission generated from the partial discharge (PD) of the accessories of a high-voltage cable system. The developed sensor head is integrated with a compact and relatively high sensitivity cylindrical elastomer. Such a sensor has a broadband frequency response and a relatively high sensitivity in a harsh environment under a high-voltage electric field. The design and fabrication of the sensor head integrated with the cylindrical elastomer is described, and a series of experiments was conducted to evaluate the sensing performance. The experimental results demonstrate that the sensitivity of our developed sensor for acoustic detection of partial discharges is 1.7 rad / ( m ⋅ Pa ) . A high frequency response up to 150 kHz is achieved. Moreover, the relatively high sensitivity for the detection of PD is verified in both the laboratory environment and gas insulated switchgear. The obtained results show the great potential application of a Michelson interferometer-based fiber sensor integrated with a cylindrical elastomer for in-situ monitoring high-voltage cable accessories for safety work.

  12. Glutamine substitution at alanine1649 in the S4-S5 cytoplasmic loop of domain 4 removes the voltage sensitivity of fast inactivation in the human heart sodium channel.

    Science.gov (United States)

    Tang, L; Chehab, N; Wieland, S J; Kallen, R G

    1998-05-01

    Normal activation-inactivation coupling in sodium channels insures that inactivation is slow at small but rapid at large depolarizations. M1651Q/M1652Q substitutions in the cytoplasmic loop connecting the fourth and fifth transmembrane segments of Domain 4 (S4-S5/D4) of the human heart sodium channel subtype 1 (hH1) affect the kinetics and voltage dependence of inactivation (Tang, L., R.G. Kallen, and R. Horn. 1996. J. Gen. Physiol. 108:89-104.). We now show that glutamine substitutions NH2-terminal to the methionines (L1646, L1647, F1648, A1649, L1650) also influence the kinetics and voltage dependence of inactivation compared with the wild-type channel. In contrast, mutations at the COOH-terminal end of the S4-S5/D4 segment (L1654, P1655, A1656) are without significant effect. Strikingly, the A1649Q mutation renders the current decay time constants virtually voltage independent and decreases the voltage dependences of steady state inactivation and the time constants for the recovery from inactivation. Single-channel measurements show that at negative voltages latency times to first opening are shorter and less voltage dependent in A1649Q than in wild-type channels; peak open probabilities are significantly smaller and the mean open times are shorter. This indicates that the rate constants for inactivation and, probably, activation are increased at negative voltages by the A1649Q mutation reminiscent of Y1494Q/ Y1495Q mutations in the cytoplasmic loop between the third and fourth domains (O'Leary, M.E., L.Q. Chen, R.G. Kallen, and R. Horn. 1995. J. Gen. Physiol. 106:641-658.). Other substitutions, A1649S and A1649V, decrease but fail to eliminate the voltage dependence of time constants for inactivation, suggesting that the decreased hydrophobicity of glutamine at either residues A1649 or Y1494Y1495 may disrupt a linkage between S4-S5/D4 and the interdomain 3-4 loop interfering with normal activation-inactivation coupling.

  13. Neutralization of Gating Charges in Domain II of the Sodium Channel α Subunit Enhances Voltage-Sensor Trapping by a β-Scorpion Toxin

    Science.gov (United States)

    Cestèle, Sandrine; Scheuer, Todd; Mantegazza, Massimo; Rochat, Hervé; Catterall, William A.

    2001-01-01

    β-Scorpion toxins shift the voltage dependence of activation of sodium channels to more negative membrane potentials, but only after a strong depolarizing prepulse to fully activate the channels. Their receptor site includes the S3–S4 loop at the extracellular end of the S4 voltage sensor in domain II of the α subunit. Here, we probe the role of gating charges in the IIS4 segment in β-scorpion toxin action by mutagenesis and functional analysis of the resulting mutant sodium channels. Neutralization of the positively charged amino acid residues in the IIS4 segment by mutation to glutamine shifts the voltage dependence of channel activation to more positive membrane potentials and reduces the steepness of voltage-dependent gating, which is consistent with the presumed role of these residues as gating charges. Surprisingly, neutralization of the gating charges at the outer end of the IIS4 segment by the mutations R850Q, R850C, R853Q, and R853C markedly enhances β-scorpion toxin action, whereas mutations R856Q, K859Q, and K862Q have no effect. In contrast to wild-type, the β-scorpion toxin Css IV causes a negative shift of the voltage dependence of activation of mutants R853Q and R853C without a depolarizing prepulse at holding potentials from −80 to −140 mV. Reaction of mutant R853C with 2-aminoethyl methanethiosulfonate causes a positive shift of the voltage dependence of activation and restores the requirement for a depolarizing prepulse for Css IV action. Enhancement of sodium channel activation by Css IV causes large tail currents upon repolarization, indicating slowed deactivation of the IIS4 voltage sensor by the bound toxin. Our results are consistent with a voltage-sensor–trapping model in which the β-scorpion toxin traps the IIS4 voltage sensor in its activated position as it moves outward in response to depolarization and holds it there, slowing its inward movement on deactivation and enhancing subsequent channel activation. Evidently

  14. Manufacturing challenges of optical current and voltage sensors for utility applications

    Energy Technology Data Exchange (ETDEWEB)

    Yakymyshyn, C.P. [Montana State Univ., Bozeman, MT (United States). Dept. of Electrical and Computer Engineering; Brubaker, M.A. [Los Alamos National Lab., NM (United States); Johnston, P.M. [Johnston (Paul M.), Raleigh, NC (United States); Reinbold, C. [ABB High Voltage Switchgear, Greensburg, PA (United States)

    1997-12-01

    Measurement of voltages and currents in power transmission and distribution systems are critical to the electric utility industry for both revenue metering and reliability. Nonconventional instrument transformers based on intensity modulation of optical signals have been reported in the literature for more than 20 years. Recently described devices using passive bulk optical sensor elements include the Electro-Optic Voltage Transducer (EOVT) and Magneto-Optic Current Transducer (MOCT). These technologies offer substantial advantages over conventional instrument transformers in accuracy, optical isolation bandwidth, environmental compatibility, weight and size. This paper describes design and manufacturing issues associated with the EOVT and the Optical Metering Unit (OMU) recently introduced by ABB with field installation results presented for prototype units in the 345 kV and 420 kV voltage classes. The OMU incorporates an EOVT and MOCT to monitor the voltage and current on power transmission lines using a single free-standing device.

  15. Manufacturing challenges of optical current and voltage sensors for utility applications

    Energy Technology Data Exchange (ETDEWEB)

    Yakymyshyn, C.P. [Montana State Univ., Bozeman, MT (United States). Dept. of Electrical and Computer Engineering; Brubaker, M.A. [Los Alamos National Lab., NM (United States); Johnston, P.M. [Johnston (Paul M.), Raleigh, NC (United States); Reinbold, C. [ABB High Voltage Switchgear, Greensburg, PA (United States)

    1997-12-01

    Measurement of voltages and currents in power transmission and distribution systems are critical to the electric utility industry for both revenue metering and reliability. Nonconventional instrument transformers based on intensity modulation of optical signals have been reported in the literature for more than 20 years. Recently described devices using passive bulk optical sensor elements include the Electro-Optic Voltage Transducer (EOVT) and Magneto-Optic Current Transducer (MOCT). These technologies offer substantial advantages over conventional instrument transformers in accuracy, optical isolation bandwidth, environmental compatibility, weight and size. This paper describes design and manufacturing issues associated with the EOVT and the Optical Metering Unit (OMU) recently introduced by ABB with field installation results presented for prototype units in the 345 kV and 420 kV voltage classes. The OMU incorporates an EOVT and MOCT to monitor the voltage and current on power transmission lines using a single free-standing device.

  16. Asymmetric functional contributions of acidic and aromatic side chains in sodium channel voltage-sensor domains

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Elstone, Fisal D; Niciforovic, Ana P

    2014-01-01

    functional phenotypes that are different from those observed previously in Kv VSDs. In contrast, and similar to results obtained with Kv channels, individually neutralizing acidic side chains with synthetic derivatives and with natural amino acid substitutions in the INC had little or no effect......Voltage-gated sodium (NaV) channels mediate electrical excitability in animals. Despite strong sequence conservation among the voltage-sensor domains (VSDs) of closely related voltage-gated potassium (KV) and NaV channels, the functional contributions of individual side chains in Nav VSDs remain...... largely enigmatic. To this end, natural and unnatural side chain substitutions were made in the S2 hydrophobic core (HC), the extracellular negative charge cluster (ENC), and the intracellular negative charge cluster (INC) of the four VSDs of the skeletal muscle sodium channel isoform (NaV1...

  17. MoS2 oxygen sensor with gate voltage stress induced performance enhancement

    Science.gov (United States)

    Tong, Yu; Lin, Zhenhua; Thong, John T. L.; Chan, Daniel S. H.; Zhu, Chunxiang

    2015-09-01

    Two-dimensional (2D) materials have recently attracted wide attention and rapidly established themselves in various applications. In particular, 2D materials are regarded as promising building blocks for gas sensors due to their high surface-to-volume ratio, ease in miniaturization, and flexibility in enabling wearable electronics. Compared with other 2D materials, MoS2 is particularly intriguing because it has been widely researched and exhibits semiconducting behavior. Here, we have fabricated MoS2 resistor based O2 sensors with a back gate configuration on a 285 nm SiO2/Si substrate. The effects of applying back gate voltage stress on O2 sensing performance have been systematically investigated. With a positive gate voltage stress, the sensor response improves and the response is improved to 29.2% at O2 partial pressure of 9.9 × 10-5 millibars with a +40 V back-gate bias compared to 21.2% at O2 partial pressure of 1.4 × 10-4 millibars without back-gate bias; while under a negative gate voltage stress of -40 V, a fast and full recovery can be achieved at room temperature. In addition, a method in determining O2 partial pressure with a detectability as low as 6.7 × 10-7 millibars at a constant vacuum pressure is presented and its potential as a vacuum gauge is briefly discussed.

  18. Numerical Electric Field Analysis of Power Status Sensor Observing Power Distribution System Taking into Account Voltage Divider Measurement Circuit

    Science.gov (United States)

    Kubo, Takuro; Furukawa, Tatsuya; Itoh, Hideaki; Fukumoto, Hisao; Wakuya, Hiroshi; Ohchi, Masashi

    We have proposed and preproducted the voltage-current waveform sensor of resin molded type for measuring the power factor and harmonics in power distribution systems. We have executed numerical electromagnetic analyses using the finite element method to estimate the characteristics and behaviours of the sensor. Although the magnetic field analyses for the current sensor have involved the measurement circuit, the electric field analyses have not included the measurement circuit for measuring voltage waveforms of power lines. In this paper, we describe the electric field analyses with the measurement circuit and prove the insulating strength of the proposed sensor permissible to the use in 22kV power distribution systems.

  19. NMR analysis of interaction of LqhalphaIT scorpion toxin with a peptide corresponding to the D4/S3-S4 loop of insect para voltage-gated sodium channel.

    Science.gov (United States)

    Schnur, Einat; Turkov, Michael; Kahn, Roy; Gordon, Dalia; Gurevitz, Michael; Anglister, Jacob

    2008-01-22

    Voltage-gated sodium channels (Navs) are large transmembrane proteins that initiate action potential in electrically excitable cells. This central role in the nervous system has made them a primary target for a large number of neurotoxins. Scorpion alpha-neurotoxins bind to Navs with high affinity and slow their inactivation, causing a prolonged action potential. Despite the similarity in their mode of action and three-dimensional structure, alpha-toxins exhibit great variations in selectivity toward insect and mammalian Navs, suggesting differences in the binding surfaces of the toxins and the channels. The scorpion alpha-toxin binding site, termed neurotoxin receptor site 3, has been shown to involve the extracellular S3-S4 loop in domain 4 of the alpha-subunit of voltage-gated sodium channels (D4/S3-S4). In this study, the binding site for peptides corresponding to the D4/S3-S4 loop of the para insect Nav was mapped on the highly insecticidal alpha-neurotoxin, LqhalphaIT, from the scorpion Leiurus quinquestriatus hebraeus, by following changes in the toxin amide 1H and 15N chemical shifts upon binding. This analysis suggests that the five-residue turn (residues LqK8-LqC12) of LqhalphaIT and those residues in its vicinity interact with the D4/S3-S4 loop of Nav. Residues LqR18, LqW38, and LqA39 could also form a patch contributing to the interaction with D4/S3-S4. Moreover, a new bioactive residue, LqV13, was identified as being important for Nav binding and specifically for the interaction with the D4/S3-S4 loop. The contribution of LqV13 to NaV binding was further verified by mutagenesis. Future studies involving other extracellular regions of Navs are required for further characterization of the structure of the LqhalphaIT-Navs binding site.

  20. Characterization and performance studies of high-voltage CMOS based pixel sensors

    CERN Document Server

    Smaranda, Dumitru Dan

    2015-01-01

    The high luminosity upgrade of the LHC will push the limits for detectors, specially the silicon trackers which are closest to the interaction point. The ATLAS CMOS Sensor R&D efort is investigating a new technology using high-voltage CMOS processes for producing pixel and strip sensors. In contrast to the currently used technology these devices implement active electronics on the sensor itself, offering a multitude of tuning parameters for achieving the best performance. My summer project revolved around characterising existing samples along with assembling and debugging hardware required for their improvement and functionality. Other tasks involved writing communication protocols using pyBAR to remotely control injection circuitry on a GPAC card, and helping various members of the group with data collection and analysis. Through the summer student programme I have had the opportunity to be part of a vibrant scientic community at the forefront of research, to create bonds with fellow students from univ...

  1. Voltage-dependent gating of hERG potassium channels

    Directory of Open Access Journals (Sweden)

    Yen May eCheng

    2012-05-01

    Full Text Available The mechanisms by which voltage-gated channels sense changes in membrane voltage and energetically couple this with opening of the ion conducting pore has been the source of significant interest. In voltage-gated potassium (Kv channels, much of our knowledge in this area comes from Shaker-type channels, for which voltage-dependent gating is quite rapid. In these channels, activation and deactivation are associated with rapid reconfiguration of the voltage-sensing domain unit that is electromechanically coupled, via the S4-S5 linker helix, to the rate-limiting opening of an intracellular pore gate. However, fast voltage-dependent gating kinetics are not typical of all Kv channels, such as Kv11.1 (human ether-a-go-go related gene, hERG, which activates and deactivates very slowly. Compared to Shaker channels, our understanding of the mechanisms underlying slow hERG gating is much poorer. Here, we present a comparative review of the structure-function relationships underlying voltage-dependent gating in Shaker and hERG channels, with a focus on the roles of the voltage sensing domain and the S4-S5 linker that couples voltage sensor movements to the pore. Measurements of gating current kinetics and fluorimetric analysis of voltage sensor movement are consistent with models suggesting that the hERG activation pathway contains a voltage independent step, which limits voltage sensor transitions. Constraints upon hERG voltage sensor movement may result from loose packing of the S4 helices and additional intra-voltage sensor counter charge interactions. More recent data suggest that key amino acid differences in the hERG voltage sensing unit and S4-S5 linker, relative to fast activating Shaker-type Kv channels, may also contribute to the increased stability of the resting state of the voltage sensor.

  2. Structural Dynamics of an Isolated-Voltage Sensor Domain in Lipid Bilayer

    Science.gov (United States)

    Chakrapani, Sudha; Cuello, Luis G.; Cortes, Marien D.; Perozo, Eduardo

    2009-01-01

    Summary A strong interplay between the voltage-sensor domain (VSD) and the pore domain (PD) underlies voltage-gated channel functions. In a few voltage-sensitive proteins, the VSD has been shown to function without a canonical PD, although its structure and oligomeric state remain unknown. Here using EPR spectroscopy we show that the isolated-VSD of KvAP can remain monomeric in reconstituted bilayer and retain a transmembrane conformation. We find that water-filled crevices extend deep into the membrane around S3, a scaffold conducive to transport of proton/cations is intrinsic to the VSD. Differences in solvent accessibility in comparison to the full-length KvAP, allowed us to define an interacting footprint of the PD on the VSD. This interaction is centered around S1 and S2 and shows a rotation of 70–100° relative to Kv1.2-Kv2.1 chimera. Sequence-conservation patterns in Kv channels, Hv channels and voltage-sensitive phosphatases reveal several near-universal features suggesting a common molecular architecture for all VSDs. PMID:18334215

  3. Analysis of the Light Propagation Model of the Optical Voltage Sensor for Suppressing Unreciprocal Errors.

    Science.gov (United States)

    Li, Hui; Fu, Zhida; Liu, Liying; Lin, Zhili; Deng, Wei; Feng, Lishuang

    2017-01-03

    An improved temperature-insensitive optical voltage sensor (OVS) with a reciprocal dual-crystal sensing method is proposed. The inducing principle of OVS reciprocity degradation is expounded by taking the different temperature fields of two crystals and the axis-errors of optical components into consideration. The key parameters pertaining to the system reciprocity degeneration in the dual-crystal sensing unit are investigated in order to optimize the optical sensing model based on the Maxwell's electromagnetic theory. The influencing principle of axis-angle errors on the system nonlinearity in the Pockels phase transfer unit is analyzed. Moreover, a novel axis-angle compensation method is proposed to improve the OVS measurement precision according to the simulation results. The experiment results show that the measurement precision of OVS is superior to ±0.2% in the temperature range from -40 °C to +60 °C, which demonstrates the excellent temperature stability of the designed voltage sensing system.

  4. Structural analysis of the S4-S5 linker of the human KCNQ1 potassium channel.

    Science.gov (United States)

    Gayen, Shovanlal; Li, Qingxin; Kang, CongBao

    2015-01-02

    KCNQ1 plays important roles in the cardiac action potential and consists of an N-terminal domain, a voltage-sensor domain, a pore domain and a C-terminal domain. KCNQ1 is a voltage-gated potassium channel and its channel activity is regulated by membrane potentials. The linker between transmembrane helices 4 and 5 (S4-S5 linker) is important for transferring the conformational changes from the voltage-sensor domain to the pore domain. In this study, the structure of the S4-S5 linker of KCNQ1 was investigated by solution NMR, circular dichroism and fluorescence spectroscopic studies. The S4-S5 linker adopted a helical structure in detergent micelles. The W248 may interact with the cell membrane.

  5. MoS{sub 2} oxygen sensor with gate voltage stress induced performance enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Yu; Lin, Zhenhua; Thong, John T. L.; Chan, Daniel S. H.; Zhu, Chunxiang, E-mail: elezhucx@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 (Singapore)

    2015-09-21

    Two-dimensional (2D) materials have recently attracted wide attention and rapidly established themselves in various applications. In particular, 2D materials are regarded as promising building blocks for gas sensors due to their high surface-to-volume ratio, ease in miniaturization, and flexibility in enabling wearable electronics. Compared with other 2D materials, MoS{sub 2} is particularly intriguing because it has been widely researched and exhibits semiconducting behavior. Here, we have fabricated MoS{sub 2} resistor based O{sub 2} sensors with a back gate configuration on a 285 nm SiO{sub 2}/Si substrate. The effects of applying back gate voltage stress on O{sub 2} sensing performance have been systematically investigated. With a positive gate voltage stress, the sensor response improves and the response is improved to 29.2% at O{sub 2} partial pressure of 9.9 × 10{sup −5} millibars with a +40 V back-gate bias compared to 21.2% at O{sub 2} partial pressure of 1.4 × 10{sup −4} millibars without back-gate bias; while under a negative gate voltage stress of −40 V, a fast and full recovery can be achieved at room temperature. In addition, a method in determining O{sub 2} partial pressure with a detectability as low as 6.7 × 10{sup −7} millibars at a constant vacuum pressure is presented and its potential as a vacuum gauge is briefly discussed.

  6. A novel bioelectrochemical BOD sensor operating with voltage input.

    Science.gov (United States)

    Modin, Oskar; Wilén, Britt-Marie

    2012-11-15

    Biochemical oxygen demand (BOD) is a measure of biodegradable compounds in water and is, for example, a common parameter to design and assess the performance of wastewater treatment plants. The conventional method to measure BOD is time consuming (5 or 7 days) and requires trained personnel. Bioelectrochemical BOD sensors designed as microbial fuel cells (MFCs), which are systems where bacteria convert organic matter into an electrical current, have emerged as an alternative to the conventional technique. In this study, a new type of bioelectrochemical BOD sensor with features that overcome some of the limitations of current MFC-type designs was developed: (1) An external voltage was applied to overcome internal resistances and allow bacteria to generate current at their full capacity, and (2) the ion exchange membrane was omitted to avoid pH shifts that would otherwise limit the applicability of the sensor for wastewaters with low alkalinity. The sensor was calibrated with an aerated nutrient medium containing acetate as the BOD source. Linear correlation (R(2) = 0.97) with charge was obtained for BOD concentrations ranging from 32 to 1280 mg/L in a reaction time of 20 h. Lowering the reaction time to 5 h resulted in lowering the measurable BOD concentration range to 320 mg/L (R(2) = 0.99). Propionate, glucose, and ethanol could also be analyzed by the sensor that was acclimated to acetate. The study demonstrates a way to design more robust and simple bioelectrochemical BOD sensors that do not suffer from the usual limitations of MFCs (high internal resistance and pH shifts).

  7. Transfer of Kv3.1 voltage sensor features to the isolated Ci-VSP voltage-sensing domain.

    Science.gov (United States)

    Mishina, Yukiko; Mutoh, Hiroki; Knöpfel, Thomas

    2012-08-22

    Membrane proteins that respond to changes in transmembrane voltage are critical in regulating the function of living cells. The voltage-sensing domains (VSDs) of voltage-gated ion channels are extensively studied to elucidate voltage-sensing mechanisms, and yet many aspects of their structure-function relationship remain elusive. Here, we transplanted homologous amino acid motifs from the tetrameric voltage-activated potassium channel Kv3.1 to the monomeric VSD of Ciona intestinalis voltage-sensitive phosphatase (Ci-VSP) to explore which portions of Kv3.1 subunits depend on the tetrameric structure of Kv channels and which properties of Kv3.1 can be transferred to the monomeric Ci-VSP scaffold. By attaching fluorescent proteins to these chimeric VSDs, we obtained an optical readout to establish membrane trafficking and kinetics of voltage-dependent structural rearrangements. We found that motifs extending from 10 to roughly 100 amino acids can be readily transplanted from Kv3.1 into Ci-VSP to form engineered VSDs that efficiently incorporate into the plasma membrane and sense voltage. Some of the functional features of these engineered VSDs are reminiscent of Kv3.1 channels, indicating that these properties do not require interactions between Kv subunits or between the voltage sensing and the pore domains of Kv channels.

  8. Design, Experiments and Simulation of Voltage Transformers on the Basis of a Differential Input D-dot Sensor

    Directory of Open Access Journals (Sweden)

    Jingang Wang

    2014-07-01

    Full Text Available Currently available traditional electromagnetic voltage sensors fail to meet the measurement requirements of the smart grid, because of low accuracy in the static and dynamic ranges and the occurrence of ferromagnetic resonance attributed to overvoltage and output short circuit. This work develops a new non-contact high-bandwidth voltage measurement system for power equipment. This system aims at the miniaturization and non-contact measurement of the smart grid. After traditional D-dot voltage probe analysis, an improved method is proposed. For the sensor to work in a self-integrating pattern, the differential input pattern is adopted for circuit design, and grounding is removed. To prove the structure design, circuit component parameters, and insulation characteristics, Ansoft Maxwell software is used for the simulation. Moreover, the new probe was tested on a 10 kV high-voltage test platform for steady-state error and transient behavior. Experimental results ascertain that the root mean square values of measured voltage are precise and that the phase error is small. The D-dot voltage sensor not only meets the requirement of high accuracy but also exhibits satisfactory transient response. This sensor can meet the intelligence, miniaturization, and convenience requirements of the smart grid.

  9. Design, experiments and simulation of voltage transformers on the basis of a differential input D-dot sensor.

    Science.gov (United States)

    Wang, Jingang; Gao, Can; Yang, Jie

    2014-07-17

    Currently available traditional electromagnetic voltage sensors fail to meet the measurement requirements of the smart grid, because of low accuracy in the static and dynamic ranges and the occurrence of ferromagnetic resonance attributed to overvoltage and output short circuit. This work develops a new non-contact high-bandwidth voltage measurement system for power equipment. This system aims at the miniaturization and non-contact measurement of the smart grid. After traditional D-dot voltage probe analysis, an improved method is proposed. For the sensor to work in a self-integrating pattern, the differential input pattern is adopted for circuit design, and grounding is removed. To prove the structure design, circuit component parameters, and insulation characteristics, Ansoft Maxwell software is used for the simulation. Moreover, the new probe was tested on a 10 kV high-voltage test platform for steady-state error and transient behavior. Experimental results ascertain that the root mean square values of measured voltage are precise and that the phase error is small. The D-dot voltage sensor not only meets the requirement of high accuracy but also exhibits satisfactory transient response. This sensor can meet the intelligence, miniaturization, and convenience requirements of the smart grid.

  10. Voltage-sensor movements describe slow inactivation of voltage-gated sodium channels II: a periodic paralysis mutation in Na(V)1.4 (L689I).

    Science.gov (United States)

    Silva, Jonathan R; Goldstein, Steve A N

    2013-03-01

    In skeletal muscle, slow inactivation (SI) of Na(V)1.4 voltage-gated sodium channels prevents spontaneous depolarization and fatigue. Inherited mutations in Na(V)1.4 that impair SI disrupt activity-induced regulation of channel availability and predispose patients to hyperkalemic periodic paralysis. In our companion paper in this issue (Silva and Goldstein. 2013. J. Gen. Physiol. http://dx.doi.org/10.1085/jgp.201210909), the four voltage sensors in Na(V)1.4 responsible for activation of channels over microseconds are shown to slowly immobilize over 1-160 s as SI develops and to regain mobility on recovery from SI. Individual sensor movements assessed via attached fluorescent probes are nonidentical in their voltage dependence, time course, and magnitude: DI and DII track SI onset, and DIII appears to reflect SI recovery. A causal link was inferred by tetrodotoxin (TTX) suppression of both SI onset and immobilization of DI and DII sensors. Here, the association of slow sensor immobilization and SI is verified by study of Na(V)1.4 channels with a hyperkalemic periodic paralysis mutation; L689I produces complex changes in SI, and these are found to manifest directly in altered sensor movements. L689I removes a component of SI with an intermediate time constant (~10 s); the mutation also impedes immobilization of the DI and DII sensors over the same time domain in support of direct mechanistic linkage. A model that recapitulates SI attributes responsibility for intermediate SI to DI and DII (10 s) and a slow component to DIII (100 s), which accounts for residual SI, not impeded by L689I or TTX.

  11. Voltage-sensor movements describe slow inactivation of voltage-gated sodium channels II: A periodic paralysis mutation in NaV1.4 (L689I)

    Science.gov (United States)

    Silva, Jonathan R.

    2013-01-01

    In skeletal muscle, slow inactivation (SI) of NaV1.4 voltage-gated sodium channels prevents spontaneous depolarization and fatigue. Inherited mutations in NaV1.4 that impair SI disrupt activity-induced regulation of channel availability and predispose patients to hyperkalemic periodic paralysis. In our companion paper in this issue (Silva and Goldstein. 2013. J. Gen. Physiol. http://dx.doi.org/10.1085/jgp.201210909), the four voltage sensors in NaV1.4 responsible for activation of channels over microseconds are shown to slowly immobilize over 1–160 s as SI develops and to regain mobility on recovery from SI. Individual sensor movements assessed via attached fluorescent probes are nonidentical in their voltage dependence, time course, and magnitude: DI and DII track SI onset, and DIII appears to reflect SI recovery. A causal link was inferred by tetrodotoxin (TTX) suppression of both SI onset and immobilization of DI and DII sensors. Here, the association of slow sensor immobilization and SI is verified by study of NaV1.4 channels with a hyperkalemic periodic paralysis mutation; L689I produces complex changes in SI, and these are found to manifest directly in altered sensor movements. L689I removes a component of SI with an intermediate time constant (∼10 s); the mutation also impedes immobilization of the DI and DII sensors over the same time domain in support of direct mechanistic linkage. A model that recapitulates SI attributes responsibility for intermediate SI to DI and DII (10 s) and a slow component to DIII (100 s), which accounts for residual SI, not impeded by L689I or TTX. PMID:23401572

  12. Temperature- and supply voltage-independent time references for wireless sensor networks

    CERN Document Server

    De Smedt, Valentijn; Dehaene, Wim

    2015-01-01

    This book investigates the possible circuit solutions to overcome the temperature- and supply voltage-sensitivity of fully-integrated time references for ultra-low-power communication in wireless sensor networks. The authors provide an elaborate theoretical introduction and literature study to enable full understanding of the design challenges and shortcomings of current oscillator implementations.  Furthermore, a closer look to the short-term as well as the long-term frequency stability of integrated oscillators is taken. Next, a design strategy is developed and applied to 5 different oscillator topologies and 1 sensor interface.All 6 implementations are subject to an elaborate study of frequency stability, phase noise, and power consumption. In the final chapter all blocks are compared to the state of the art. The main goals of this book are: • to provide a comprehensive overview of timing issues and solutions in wireless sensor networks; • to gain understanding of all underlying mechanisms by starti...

  13. Growth and Characterization of Single Crystalline Bi4Ge3O12 Fibers for Electrooptic High Voltage Sensors

    Directory of Open Access Journals (Sweden)

    Stephan Wildermuth

    2013-01-01

    Full Text Available The micro-pulling-down technique for crystalline fiber growth is employed to grow fibers and thin rods of bismuth germanate, Bi4Ge3O12 (BGO, for use in electrooptic high voltage sensors. The motivation is the growth of fibers that are considerably longer than the typical lengths (100–250 mm that are achieved by more conventional growth techniques like the Czochralski technique. At a given voltage (several hundred kilovolts in high voltage substation applications longer sensors result in lower electric field strengths and therefore more compact and simpler electric insulation. BGO samples with lengths up to 850 mm and thicknesses from 300 μm to 3 mm were grown. Particular challenges in the growth of BGO fibers are addressed. The relevant optical properties of the fibers are characterized, and the electrooptic response is investigated at voltages up to .

  14. A Complex Permittivity Based Sensor for the Electrical Characterization of High-Voltage Transformer Oils

    Directory of Open Access Journals (Sweden)

    Panayota Vassiliou

    2005-05-01

    Full Text Available This work investigates the use of a specially designed cylindrical metal cell, inorder to obtain complex permittivity and tanδ data of highly insulating High Voltage (HVtransformer oil samples. The data are obtained at a wide range of frequencies and operationtemperatures to demonstrate the polarization phenomena and the thermally stimulatedeffects. Such complex permittivity measurements may be utilized as a criterion for theservice life prediction of oil field electrical equipment (OFEE. Therefore, by one set ofmeasurements on a small oil volume, data may be provided on the impending termination,or continuation of the transformer oil service life. The oil incorporating cell, attached to theappropriate measuring units, could be described as a complex permittivity sensor. In thiswork, the acquired dielectric data from a great number of operating distribution networkpower transformers were correlated to corresponding physicochemical ones to demonstratethe future potential employment of the proposed measuring technique.

  15. Leaky sodium channels from voltage sensor mutations in periodic paralysis, but not paramyotonia

    Science.gov (United States)

    Francis, David G.; Rybalchenko, Volodymyr; Struyk, Arie

    2011-01-01

    Background: Hypokalemic periodic paralysis (HypoPP) is associated with mutations in either the CaV1.1 calcium channel or the NaV1.4 sodium channel. Some NaV1.4 HypoPP mutations have been shown to cause an anomalous inward current that may contribute to the attacks of paralysis. Herein, we test whether disease-associated NaV1.4 mutations in previously untested homologous regions of the channel also give rise to the anomalous current. Methods: The functional properties of mutant NaV1.4 channels were studied with voltage-clamp techniques in an oocyte expression system. Results: The HypoPP mutation NaV1.4-R1132Q conducts an anomalous gating pore current, but the homologous R1448C mutation in paramyotonia congenita does not. Conclusions: Gating pore currents arising from missense mutations at arginine residues in the voltage sensor domains of NaV1.4 are a common feature of HypoPP mutant channels and contribute to the attacks of paralysis. PMID:21490317

  16. Analysis of the Light Propagation Model of the Optical Voltage Sensor for Suppressing Unreciprocal Errors

    Science.gov (United States)

    Li, Hui; Fu, Zhida; Liu, Liying; Lin, Zhili; Deng, Wei; Feng, Lishuang

    2017-01-01

    An improved temperature-insensitive optical voltage sensor (OVS) with a reciprocal dual-crystal sensing method is proposed. The inducing principle of OVS reciprocity degradation is expounded by taking the different temperature fields of two crystals and the axis-errors of optical components into consideration. The key parameters pertaining to the system reciprocity degeneration in the dual-crystal sensing unit are investigated in order to optimize the optical sensing model based on the Maxwell's electromagnetic theory. The influencing principle of axis-angle errors on the system nonlinearity in the Pockels phase transfer unit is analyzed. Moreover, a novel axis-angle compensation method is proposed to improve the OVS measurement precision according to the simulation results. The experiment results show that the measurement precision of OVS is superior to ±0.2% in the temperature range from −40 °C to +60 °C, which demonstrates the excellent temperature stability of the designed voltage sensing system. PMID:28054951

  17. Chloride Anions Regulate Kinetics but Not Voltage-Sensor Qmax of the Solute Carrier SLC26a5.

    Science.gov (United States)

    Santos-Sacchi, Joseph; Song, Lei

    2016-06-07

    In general, SLC26 solute carriers serve to transport a variety of anions across biological membranes. However, prestin (SLC26a5) has evolved, now serving as a motor protein in outer hair cells (OHCs) of the mammalian inner ear and is required for cochlear amplification, a mechanical feedback mechanism to boost auditory performance. The mechanical activity of the OHC imparted by prestin is driven by voltage and controlled by anions, chiefly intracellular chloride. Current opinion is that chloride anions control the Boltzmann characteristics of the voltage sensor responsible for prestin activity, including Qmax, the total sensor charge moved within the membrane, and Vh, a measure of prestin's operating voltage range. Here, we show that standard narrow-band, high-frequency admittance measures of nonlinear capacitance (NLC), an alternate representation of the sensor's charge-voltage (Q-V) relationship, is inadequate for assessment of Qmax, an estimate of the sum of unitary charges contributed by all voltage sensors within the membrane. Prestin's slow transition rates and chloride-binding kinetics adversely influence these estimates, contributing to the prevalent concept that intracellular chloride level controls the quantity of sensor charge moved. By monitoring charge movement across frequency, using measures of multifrequency admittance, expanded displacement current integration, and OHC electromotility, we find that chloride influences prestin kinetics, thereby controlling charge magnitude at any particular frequency of interrogation. Importantly, however, this chloride dependence vanishes as frequency decreases, with Qmax asymptoting at a level irrespective of the chloride level. These data indicate that prestin activity is significantly low-pass in the frequency domain, with important implications for cochlear amplification. We also note that the occurrence of voltage-dependent charge movements in other SLC26 family members may be hidden by inadequate

  18. Position and motions of the S4 helix during opening of the Shaker potassium channel.

    Science.gov (United States)

    Phillips, L Revell; Swartz, Kenton J

    2010-12-01

    The four voltage sensors in voltage-gated potassium (Kv) channels activate upon membrane depolarization and open the pore. The location and motion of the voltage-sensing S4 helix during the early activation steps and the final opening transition are unresolved. We studied Zn(2+) bridges between two introduced His residues in Shaker Kv channels: one in the R1 position at the outer end of the S4 helix (R362H), and another in the S5 helix of the pore domain (A419H or F416H). Zn(2+) bridges readily form between R362H and A419H in open channels after the S4 helix has undergone its final motion. In contrast, a distinct bridge forms between R362H and F416H after early S4 activation, but before the final S4 motion. Both bridges form rapidly, providing constraints on the average position of S4 relative to the pore. These results demonstrate that the outer ends of S4 and S5 remain in close proximity during the final opening transition, with the S4 helix translating a significant distance normal to the membrane plane.

  19. Laser ultrasonic analysis of normal modes generated by a voltage pulse on an AT quartz sensor.

    Science.gov (United States)

    Goossens, Jozefien; Martinez, Loïc; Glorieux, Christ; Wilkie-Chancellier, Nicolas; Ehssein, Chighali Ould; Serfaty, Stéphane

    2006-12-22

    Laser ultrasonic detection is a versatile and highly sensitive tool for the observation of surface waves. In the following study, laser ultrasonic detection is used for the experimental study of spurious normal vibration modes of a disk quartz sensor excited by a voltage pulse. The AT cut crystal (cut of the crystal relative to the the main crystallographic axis is 35.25 degrees) is optimal for generating mainly thickness-shear vibrations (central frequency 6 MHz) on the quartz surface. However, resulting from shear-to-longitudinal and shear-to-surface mode conversion, and from the weak coupling with the other crystallographic axes, other modes (thickness-compressional and bending modes) are always present in the plate response. Since the laser vibrometer is sensitive to normal displacements, the laser investigation shows waves that can be considered as unwanted for the AT quartz used as a shear sensor. The scanned three dimensional (3D) amplitude-space-time signals are carefully analysed using their representation in three dual Fourier domains (space-time, wave number-frequency). Results on the transient analysis of the waves, the normal bending modes and the dispersion curves are shown.

  20. Cable Crosstalk Suppression with Two-Wire Voltage Feedback Method for Resistive Sensor Array.

    Science.gov (United States)

    Wu, Jianfeng; He, Shangshang; Li, Jianqing; Song, Aiguo

    2016-01-01

    Using a long, flexible test cable connected with a one-wire voltage feedback circuit, a resistive tactile sensor in a shared row-column fashion exhibited flexibility in robotic operations but suffered from crosstalk caused by the connected cable due to its wire resistances and its contacted resistances. Firstly, we designed a new non-scanned driving-electrode (VF-NSDE) circuit using two wires for every row line and every column line to reduce the crosstalk caused by the connected cables in the circuit. Then, an equivalent resistance expression of the element being tested (EBT) for the two-wire VF-NSDE circuit was analytically derived. Following this, the one-wire VF-NSDE circuit and the two-wire VF-NSDE circuit were evaluated by simulation experiments. Finally, positive features of the proposed method were verified with the experiments of a two-wire VF-NSDE prototype circuit. The experiment results show that the two-wire VF-NSDE circuit can greatly reduce the crosstalk error caused by the cables in the 2-D networked resistive sensor array.

  1. An LMS Programming Scheme and Floating-Gate Technology Enabled Trimmer-Less and Low Voltage Flame Detection Sensor

    Science.gov (United States)

    Iglesias-Rojas, Juan Carlos; Gomez-Castañeda, Felipe; Moreno-Cadenas, Jose Antonio

    2017-01-01

    In this paper, a Least Mean Square (LMS) programming scheme is used to set the offset voltage of two operational amplifiers that were built using floating-gate transistors, enabling a 0.95 VRMS trimmer-less flame detection sensor. The programming scheme is capable of setting the offset voltage over a wide range of values by means of electron injection. The flame detection sensor consists of two programmable offset operational amplifiers; the first amplifier serves as a 26 μV offset voltage follower, whereas the second amplifier acts as a programmable trimmer-less voltage comparator. Both amplifiers form the proposed sensor, whose principle of functionality is based on the detection of the electrical changes produced by the flame ionization. The experimental results show that it is possible to measure the presence of a flame accurately after programming the amplifiers with a maximum of 35 LMS-algorithm iterations. Current commercial flame detectors are mainly used in absorption refrigerators and large industrial gas heaters, where a high voltage AC source and several mechanical trimmings are used in order to accurately measure the presence of the flame. PMID:28613250

  2. An LMS Programming Scheme and Floating-Gate Technology Enabled Trimmer-Less and Low Voltage Flame Detection Sensor.

    Science.gov (United States)

    Iglesias-Rojas, Juan Carlos; Gomez-Castañeda, Felipe; Moreno-Cadenas, Jose Antonio

    2017-06-14

    In this paper, a Least Mean Square (LMS) programming scheme is used to set the offset voltage of two operational amplifiers that were built using floating-gate transistors, enabling a 0.95 VRMS trimmer-less flame detection sensor. The programming scheme is capable of setting the offset voltage over a wide range of values by means of electron injection. The flame detection sensor consists of two programmable offset operational amplifiers; the first amplifier serves as a 26 μV offset voltage follower, whereas the second amplifier acts as a programmable trimmer-less voltage comparator. Both amplifiers form the proposed sensor, whose principle of functionality is based on the detection of the electrical changes produced by the flame ionization. The experimental results show that it is possible to measure the presence of a flame accurately after programming the amplifiers with a maximum of 35 LMS-algorithm iterations. Current commercial flame detectors are mainly used in absorption refrigerators and large industrial gas heaters, where a high voltage AC source and several mechanical trimmings are used in order to accurately measure the presence of the flame.

  3. Control of a Two-Stage Direct Power Converter with a Single Voltage Sensor Mounted in the Intermediary Circuit

    DEFF Research Database (Denmark)

    Klumpner, Christian; Wheeler, P.; Blaabjerg, Frede

    2004-01-01

    Controlling a converter requires not only a powerful processors but also accurate voltage and current sensors and fast and precise analogue-digital converters, which increase the cost per kW of the assembly, especially in the low power range. A matrix converter requires less transducers than a ba...

  4. Mechanism of electromechanical coupling in voltage-gated potassium channels

    Directory of Open Access Journals (Sweden)

    Rikard eBlunck

    2012-09-01

    Full Text Available Voltage-gated ion channels play a central role in the generation of action potentials in the nervous system. They are selective for one type of ion – sodium, calcium or potassium. Voltage-gated ion channels are composed of a central pore that allows ions to pass through the membrane and four peripheral voltage sensing domains that respond to changes in the membrane potential. Upon depolarization, voltage sensors in voltage-gated potassium channels (Kv undergo conformational changes driven by positive charges in the S4 segment and aided by pairwise electrostatic interactions with the surrounding voltage sensor. Structure-function relations of Kv channels have been investigated in detail, and the resulting models on the movement of the voltage sensors now converge to a consensus; the S4 segment undergoes a combined movement of rotation, tilt and vertical displacement in order to bring 3-4 e+ each through the electric field focused in this region. Nevertheless, the mechanism by which the voltage sensor movement leads to pore opening, the electromechanical coupling, is still not fully understood. Thus, recently, electromechanical coupling in different Kv channels has been investigated with a multitude of techniques including electrophysiology, 3D crystal structures, fluorescence spectroscopy and molecular dynamics simulations. Evidently, the S4-S5 linker, the covalent link between the voltage sensor and pore, plays a crucial role. The linker transfers the energy from the voltage sensor movement to the pore domain via an interaction with the S6 C-termini, which are pulled open during gating. In addition, other contact regions have been proposed. This review aims to provide (i an in-depth comparison of the molecular mechanisms of electromechanical coupling in different Kv channels; (ii insight as to how the voltage sensor and pore domain influence one another; and (iii theoretical predictions on the movement of the cytosolic face of the KV channels

  5. Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears

    Directory of Open Access Journals (Sweden)

    Xiaoxing Zhang

    2016-07-01

    Full Text Available In this study a new built-in ultrahigh frequency (UHF antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor.

  6. Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears.

    Science.gov (United States)

    Zhang, Xiaoxing; Cheng, Zheng; Gui, Yingang

    2016-07-26

    In this study a new built-in ultrahigh frequency (UHF) antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD) detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor.

  7. Bimane fluorescence scanning suggests secondary structure near the S3-S4 linker of BK channels.

    Science.gov (United States)

    Semenova, Nina P; Abarca-Heidemann, Karin; Loranc, Eva; Rothberg, Brad S

    2009-04-17

    Gating of large conductance Ca(2+)-activated K(+) channels (BK or maxi-K channels) is controlled by a Ca(2+)-sensor, formed by the channel cytoplasmic C-terminal domain, and a voltage sensor, formed by its S0-S4 transmembrane helices. Here we analyze structural properties of a portion of the BK channel voltage sensing domain, the S3-S4 linker, using fluorescence lifetime spectroscopy. Single residues in the S3-S4 linker region were substituted with cysteine, and the cysteine-substituted mutants were expressed in CHO cells and covalently labeled with the sulfhydryl-reactive fluorophore monobromo-trimethylammonio-bimane (qBBr). qBBr fluorescence is quenched by tryptophan and, to a lesser extent, tyrosine side chains. We found that qBBr fluorescence in several of the labeled cysteine-substituted channels shows position-specific quenching, as indicated by increase of the brief lifetime component of the qBBr fluorescence decay. Quenching was reduced with the mutation W203F (in the S4 segment), suggesting that Trp-203 acts as a quenching group. Our results suggest a working hypothesis for the secondary structure of the BK channel S3-S4 region, and places residues Leu-204, Gly-205, and Leu-206 within the extracellular end of the S4 helix.

  8. Regional flexibility in the S4-S5 linker regulates hERG channel closed-state stabilization.

    Science.gov (United States)

    Hull, Christina M; Sokolov, Stanislav; Van Slyke, Aaron C; Claydon, Tom W

    2014-10-01

    hERG K(+) channel function is vital for normal cardiac rhythm, yet the mechanisms underlying the unique biophysical characteristics of the channel, such as slow activation and deactivation gating, are incompletely understood. The S4-S5 linker is thought to transduce voltage sensor movement to opening of the pore gate, but may also integrate signals from cytoplasmic domains. Previously, we showed that substitutions of G546 within the S4-S5 linker destabilize the closed state of the channel. Here, we present results of a glycine-scan in the background of 546L. We demonstrate site-specific restoration of WT-like activation which suggests that flexibility in the N-terminal portion of the S4-S5 linker is critical for the voltage dependence of hERG channel activation. In addition, we show that the voltage dependence of deactivation, which was recently shown to be left-shifted from that of activation due to voltage sensor mode-shift, is also modulated by the S4-S5 linker. The G546L mutation greatly attenuated the coupling of voltage sensor mode-shift to the pore gate without altering the mode-shift itself. Indeed, all of the S4-S5 linker mutations tested similarly reduced coupling of the mode-shift to the pore gate. These data demonstrate a key role for S4-S5 linker in the unique activation and deactivation gating of hERG channels. Furthermore, uncoupling of the mode-shift to the pore by S4-S5 linker mutations parallels the effects of mutations in the N-terminus suggestive of functional interactions between the two regions.

  9. Enhanced low current, voltage, and power dissipation measurements via Arduino Uno microcontroller with modified commercially available sensors

    Science.gov (United States)

    Tanner, Meghan; Eckel, Ryan; Senevirathne, Indrajith

    The versatility, simplicity, and robustness of Arduino microcontroller architecture have won a huge following with increasingly serious engineering and physical science applications. Arduino microcontroller environment coupled with commercially available sensors have been used to systematically measure, record, and analyze low currents, low voltages and corresponding dissipated power for assessing secondary physical properties in a diverse array of engineering systems. Setup was assembled via breadboard, wire, and simple soldering with an Arduino Uno with ATmega328P microcontroller connected to a PC. The microcontroller was programmed with Arduino Software while the bootloader was used to upload the code. Commercial Hall effect current sensor modules ACS712 and INA169 current shunt monitor was used to measure corresponding low to ultra-low currents and voltages. Stable measurement data was obtained via sensors and compared with corresponding oscilloscope measurements to assess reliability and uncertainty. Sensor breakout boards were modified to enhance the sensitivity of the measurements and to expand the applicability. Discussion of these measurements will focus on capabilities, capacities and limitations of the systems with examples of possible applications. Lock Haven Nanotechnology Program.

  10. A Tracker for the Mu3e Experiment based on High-Voltage Monolithic Active Pixel Sensors

    CERN Document Server

    Berger, Niklaus; Bachmann, Sebastian; Kiehn, Moritz; Perić, Ivan; Perrevoort, Ann-Kathrin; Philipp, Raphael; Schöning, André; Stumpf, Kevin; Wiedner, Dirk; Windelband, Bernd; Zimmermann, Marco

    2013-01-01

    The Mu3e experiment searches for the lepton flavour violating decay mu+ -> e+e-e+, aiming for a branching fraction sensitivity of 10^-16. This requires an excellent momentum resolution for low energy electrons, high rate capability and a large acceptance. In order to minimize multiple scattering, the amount of material has to be as small as possible. These challenges can be met with a tracker built from high-voltage monolithic active pixel sensors (HV-MAPS), which can be thinned to 50 um and which incorporate the complete read-out electronics on the sensor chip. To further minimise material, the sensors are supported by a mechanical structure built from 25 um thick Kapton foil and cooled with gaseous helium.

  11. A tracker for the Mu3e experiment based on high-voltage monolithic active pixel sensors

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Niklaus, E-mail: nberger@physi.uni-heidelberg.de [Physikalisches Institut, Heidelberg University, Heidelberg (Germany); Augustin, Heiko; Bachmann, Sebastian; Kiehn, Moritz [Physikalisches Institut, Heidelberg University, Heidelberg (Germany); Perić, Ivan [Zentralinstitut für technische Informatik, Heidelberg University, Mannheim (Germany); Perrevoort, Ann-Kathrin; Philipp, Raphael; Schöning, André; Stumpf, Kevin; Wiedner, Dirk; Windelband, Bernd; Zimmermann, Marco [Physikalisches Institut, Heidelberg University, Heidelberg (Germany)

    2013-12-21

    The Mu3e experiment searches for the lepton flavour violating decay μ{sup +}→e{sup +}e{sup −}e{sup +}, aiming for a branching fraction sensitivity of 10{sup −16}. This requires an excellent momentum resolution for low energy electrons, high rate capability and a large acceptance. In order to minimise multiple scattering, the amount of material has to be as small as possible. These challenges can be met with a tracker built from high-voltage monolithic active pixel sensors (HV-MAPS), which can be thinned to 50μm and which incorporate the complete read-out electronics on the sensor chip. To further minimise material, the sensors are supported by a mechanical structure built from 25μm thick Kapton foil and cooled with gaseous helium.

  12. The Mechanism of Voltage Dependent Gating of the NaChBac Prokaryotic Sodium Channel

    Science.gov (United States)

    Decaen, Paul G.

    Electrical signaling in cells depends on selective conductance of ions through membrane proteins called 'voltage gated ion channels'. These channels are characterized by their ability turn on and off the flow of ionic current by opening and closing their conductive pore in response to changes in membrane potential. The opening and closing of the pore is a mechanically linked to conformational movement of the positively charged fourth transmembrane segment (S4) in 'the voltage sensor' region. How the S4 moves in response to membrane potential is a controversial subject. In this thesis, we used the prokaryotic sodium channel NaChBac as our model sodium channel to study voltage dependent movement of the S4 in the voltage sensor. We use a disulfide-locking method where we introduced pairs of cysteines in the voltage sensor that crosslink and trap the S4 in its path after depolarization. We screened over one hundred mutations of the NaChBac channel in the whole cell patch clamp assay and demonstrated discrete and sequential voltage dependent ion pair interactions that occur in at least three states between the positively charged residues of the S4 segment and the acidic residues in the S1, S2 and S3 segments. In conjunction with structural modeling of the voltage sensor and our disulfide locking data, we propose that the S4 moves in and out of the plane of the membrane 8-13 A, forming distinct gating charge interactions with counter charges of the voltage sensor and adopts a 310 helix over a portion of its structure during activation. These findings are compatible with the sliding helix model and refine our understanding of the structural determinates of voltage sensor function in voltage gated ion channels.

  13. Influence of Ambient Humidity on the Voltage Response of Ionic Polymer-Metal Composite Sensor.

    Science.gov (United States)

    Zhu, Zicai; Horiuchi, Tetsuya; Kruusamäe, Karl; Chang, Longfei; Asaka, Kinji

    2016-03-31

    Electrical potential based on ion migration exists not only in natural systems but also in ionic polymer materials. In order to investigate the influence of ambient humidity on voltage response, classical Au-Nafion IPMC was chosen as the reference sample. Voltage response under a bending deformation was measured in two ways: first, continuous measurement of voltage response in the process of absorption and desorption of water to study the tendency of voltage variation at all water states; second, measurements at multiple fixed ambient humidity levels to characterize the process of voltage response quantitatively. Ambient humidity influences the voltage response mainly by varying water content in ionic polymer. Under a step bending, the amplitude of initial voltage peak first increases and then decreases as the ambient humidity and the inherent water content decrease. This tendency is explained semiquantitatively by mass storage capacity related to the stretchable state of the Nafion polymer network. Following the initial peak, the voltage shows a slow decay to a steady state, which is first characterized in this paper. The relative voltage decay during the steady state always decreases as the ambient humidity is lowered. It is ascribed to progressive increase of the ratio between the water molecules in the cation hydration shell to the free water. Under sinusoidal mechanical bending excitation in the range of 0.1-10 Hz, the voltage magnitude increases with frequency at high ambient humidity but decreases with frequency at low ambient humidity. The relationship is mainly controlled by the voltage decay effect and the response speed.

  14. Low-Voltage 96 dB Snapshot CMOS Image Sensor with 4.5 nW Power Dissipation per Pixel

    Directory of Open Access Journals (Sweden)

    Orly Yadid-Pecht

    2012-07-01

    Full Text Available Modern “smart” CMOS sensors have penetrated into various applications, such as surveillance systems, bio-medical applications, digital cameras, cellular phones and many others. Reducing the power of these sensors continuously challenges designers. In this paper, a low power global shutter CMOS image sensor with Wide Dynamic Range (WDR ability is presented. This sensor features several power reduction techniques, including a dual voltage supply, a selective power down, transistors with different threshold voltages, a non-rationed logic, and a low voltage static memory. A combination of all these approaches has enabled the design of the low voltage “smart” image sensor, which is capable of reaching a remarkable dynamic range, while consuming very low power. The proposed power-saving solutions have allowed the maintenance of the standard architecture of the sensor, reducing both the time and the cost of the design. In order to maintain the image quality, a relation between the sensor performance and power has been analyzed and a mathematical model, describing the sensor Signal to Noise Ratio (SNR and Dynamic Range (DR as a function of the power supplies, is proposed. The described sensor was implemented in a 0.18 um CMOS process and successfully tested in the laboratory. An SNR of 48 dB and DR of 96 dB were achieved with a power dissipation of 4.5 nW per pixel.

  15. Low-voltage 96 dB snapshot CMOS image sensor with 4.5 nW power dissipation per pixel.

    Science.gov (United States)

    Spivak, Arthur; Teman, Adam; Belenky, Alexander; Yadid-Pecht, Orly; Fish, Alexander

    2012-01-01

    Modern "smart" CMOS sensors have penetrated into various applications, such as surveillance systems, bio-medical applications, digital cameras, cellular phones and many others. Reducing the power of these sensors continuously challenges designers. In this paper, a low power global shutter CMOS image sensor with Wide Dynamic Range (WDR) ability is presented. This sensor features several power reduction techniques, including a dual voltage supply, a selective power down, transistors with different threshold voltages, a non-rationed logic, and a low voltage static memory. A combination of all these approaches has enabled the design of the low voltage "smart" image sensor, which is capable of reaching a remarkable dynamic range, while consuming very low power. The proposed power-saving solutions have allowed the maintenance of the standard architecture of the sensor, reducing both the time and the cost of the design. In order to maintain the image quality, a relation between the sensor performance and power has been analyzed and a mathematical model, describing the sensor Signal to Noise Ratio (SNR) and Dynamic Range (DR) as a function of the power supplies, is proposed. The described sensor was implemented in a 0.18 um CMOS process and successfully tested in the laboratory. An SNR of 48 dB and DR of 96 dB were achieved with a power dissipation of 4.5 nW per pixel.

  16. Tyrosine Residues from the S4-S5 Linker of Kv11.1 Channels Are Critical for Slow Deactivation.

    Science.gov (United States)

    Ng, Chai-Ann; Gravel, Andrée E; Perry, Matthew D; Arnold, Alexandre A; Marcotte, Isabelle; Vandenberg, Jamie I

    2016-08-12

    Slow deactivation of Kv11.1 channels is critical for its function in the heart. The S4-S5 linker, which joins the voltage sensor and pore domains, plays a critical role in this slow deactivation gating. Here, we use NMR spectroscopy to identify the membrane-bound surface of the S4S5 linker, and we show that two highly conserved tyrosine residues within the KCNH subfamily of channels are membrane-associated. Site-directed mutagenesis and electrophysiological analysis indicates that Tyr-542 interacts with both the pore domain and voltage sensor residues to stabilize activated conformations of the channel, whereas Tyr-545 contributes to the slow kinetics of deactivation by primarily stabilizing the transition state between the activated and closed states. Thus, the two tyrosine residues in the Kv11.1 S4S5 linker play critical but distinct roles in the slow deactivation phenotype, which is a hallmark of Kv11.1 channels.

  17. The piezoelectronic stress transduction switch for very large-scale integration, low voltage sensor computation, and radio frequency applications

    Science.gov (United States)

    Magdǎu, I.-B.; Liu, X.-H.; Kuroda, M. A.; Shaw, T. M.; Crain, J.; Solomon, P. M.; Newns, D. M.; Martyna, G. J.

    2015-08-01

    The piezoelectronic transduction switch is a device with potential as a post-CMOS transistor due to its predicted multi-GHz, low voltage performance on the VLSI-scale. However, the operating principle of the switch has wider applicability. We use theory and simulation to optimize the device across a wide range of length scales and application spaces and to understand the physics underlying its behavior. We show that the four-terminal VLSI-scale switch can operate at a line voltage of 115 mV while as a low voltage-large area device, ≈200 mV operation at clock speeds of ≈2 GHz can be achieved with a desirable 104 On/Off ratio—ideal for on-board computing in sensors. At yet larger scales, the device is predicted to operate as a fast (≈250 ps) radio frequency (RF) switch exhibiting high cyclability, low On resistance and low Off capacitance, resulting in a robust switch with a RF figure of merit of ≈4 fs. These performance benchmarks cannot be approached with CMOS which has reached fundamental limits. In detail, a combination of finite element modeling and ab initio calculations enables prediction of switching voltages for a given design. A multivariate search method then establishes a set of physics-based design rules, discovering the key factors for each application. The results demonstrate that the piezoelectronic transduction switch can offer fast, low power applications spanning several domains of the information technology infrastructure.

  18. Analysis of a three-part 230 kV optical voltage transducer with multiple electric field sensors

    Energy Technology Data Exchange (ETDEWEB)

    Namedanian, M.; Mozafari, M.; Razavi, S. [Niroo Research Inst., Tehran (Iran, Islamic Republic of). Dept. of Electronics, Control and Instrumentation

    2008-07-01

    A 3-part optical voltage transducer (OVT) was used as a replacement for conventional inductive and capacitive transformers. A quadrature method was used to position the sensors. The OVT was designed using a finite element simulation program with a particle swarm optimization (PSO) algorithm. Each section of the 3-part insulator consisted of a fiberglass tube with silicon rubber shedding. A corona ring was positioned around the top of the insulator. The simulations were conducted to demonstrate various perturbation scenarios and examine the potential distorted behaviour of the electric field. Ratio errors and voltage differences occurring from the various perturbations were calculated in order to determine the optimal positions and weights of the OVT. Results of the study indicated that the OVT will meet all standard requirements and be cheaper and easier to implement than conventional capacitive or inductive transformers. 8 refs., 3 tabs., 5 figs.

  19. Rapid Cellular Phenotyping of Human Pluripotent Stem Cell-Derived Cardiomyocytes using a Genetically Encoded Fluorescent Voltage Sensor

    Directory of Open Access Journals (Sweden)

    Jordan S. Leyton-Mange

    2014-02-01

    Full Text Available In addition to their promise in regenerative medicine, pluripotent stem cells have proved to be faithful models of many human diseases. In particular, patient-specific stem cell-derived cardiomyocytes recapitulate key features of several life-threatening cardiac arrhythmia syndromes. For both modeling and regenerative approaches, phenotyping of stem cell-derived tissues is critical. Cellular phenotyping has largely relied upon expression of lineage markers rather than physiologic attributes. This is especially true for cardiomyocytes, in part because electrophysiological recordings are labor intensive. Likewise, most optical voltage indicators suffer from phototoxicity, which damages cells and degrades signal quality. Here we present the use of a genetically encoded fluorescent voltage indicator, ArcLight, which we demonstrate can faithfully report transmembrane potentials in human stem cell-derived cardiomyocytes. We demonstrate the application of this fluorescent sensor in high-throughput, serial phenotyping of differentiating cardiomyocyte populations and in screening for drug-induced cardiotoxicity.

  20. Involvement of the S4-S5 linker and the C-linker domain regions to voltage-gating in plant Shaker channels: comparison with animal HCN and Kv channels.

    Science.gov (United States)

    Nieves-Cordones, Manuel; Gaillard, Isabelle

    2014-01-01

    Among the different transport systems present in plant cells, Shaker channels constitute the major pathway for K(+) in the plasma membrane. Plant Shaker channels are members of the 6 transmembrane-1 pore (6TM-1P) cation channel superfamily as the animal Shaker (Kv) and HCN channels. All these channels are voltage-gated K(+) channels: Kv channels are outward-rectifiers, opened at depolarized voltages and HCN channels are inward-rectifiers, opened by membrane hyperpolarization. Among plant Shaker channels, we can find outward-rectifiers, inward-rectifiers and also weak-rectifiers, with weak voltage dependence. Despite the absence of crystal structures of plant Shaker channels, functional analyses coupled to homology modeling, mostly based on Kv and HCN crystals, have permitted the identification of several regions contributing to plant Shaker channel gating. In the present mini-review, we make an update on the voltage-gating mechanism of plant Shaker channels which seem to be comparable to that proposed for HCN channels.

  1. Optimal Geometry of CMOS Voltage-Mode and Current-Mode Vertical Magnetic Hall Sensors

    OpenAIRE

    2015-01-01

    Four different geometries of a vertical Hall sensor\\ud are presented and studied in this paper. The current spinning\\ud technique compensates for the offset and the sensors, driven in\\ud current-mode, provide a differential signal current for a possible\\ud capacitive integration over a defined time-slot. The sensors have\\ud been fabricated using a 6-metal 0.18-μm CMOS technology and\\ud fully experimentally tested. The optimal solution will be further\\ud investigated for bendable electronics. ...

  2. Fabrication of Ultra-Thin Printed Organic TFT CMOS Logic Circuits Optimized for Low-Voltage Wearable Sensor Applications.

    Science.gov (United States)

    Takeda, Yasunori; Hayasaka, Kazuma; Shiwaku, Rei; Yokosawa, Koji; Shiba, Takeo; Mamada, Masashi; Kumaki, Daisuke; Fukuda, Kenjiro; Tokito, Shizuo

    2016-05-09

    Ultrathin electronic circuits that can be manufactured by using conventional printing technologies are key elements necessary to realize wearable health sensors and next-generation flexible electronic devices. Due to their low level of power consumption, complementary (CMOS) circuits using both types of semiconductors can be easily employed in wireless devices. Here, we describe ultrathin CMOS logic circuits, for which not only the source/drain electrodes but also the semiconductor layers were printed. Both p-type and n-type organic thin film transistor devices were employed in a D-flip flop circuit in the newly developed stacked structure and exhibited excellent electrical characteristics, including good carrier mobilities of 0.34 and 0.21 cm(2) V(-1) sec(-1), and threshold voltages of nearly 0 V with low operating voltages. These printed organic CMOS D-flip flop circuits exhibit operating frequencies of 75 Hz and demonstrate great potential for flexible and printed electronics technology, particularly for wearable sensor applications with wireless connectivity.

  3. Fabrication of Ultra-Thin Printed Organic TFT CMOS Logic Circuits Optimized for Low-Voltage Wearable Sensor Applications

    Science.gov (United States)

    Takeda, Yasunori; Hayasaka, Kazuma; Shiwaku, Rei; Yokosawa, Koji; Shiba, Takeo; Mamada, Masashi; Kumaki, Daisuke; Fukuda, Kenjiro; Tokito, Shizuo

    2016-05-01

    Ultrathin electronic circuits that can be manufactured by using conventional printing technologies are key elements necessary to realize wearable health sensors and next-generation flexible electronic devices. Due to their low level of power consumption, complementary (CMOS) circuits using both types of semiconductors can be easily employed in wireless devices. Here, we describe ultrathin CMOS logic circuits, for which not only the source/drain electrodes but also the semiconductor layers were printed. Both p-type and n-type organic thin film transistor devices were employed in a D-flip flop circuit in the newly developed stacked structure and exhibited excellent electrical characteristics, including good carrier mobilities of 0.34 and 0.21 cm2 V‑1 sec‑1, and threshold voltages of nearly 0 V with low operating voltages. These printed organic CMOS D-flip flop circuits exhibit operating frequencies of 75 Hz and demonstrate great potential for flexible and printed electronics technology, particularly for wearable sensor applications with wireless connectivity.

  4. Ultra-low power sensor for autonomous non-invasive voltage measurement in IoT solutions for energy efficiency

    Science.gov (United States)

    Villani, Clemente; Balsamo, Domenico; Brunelli, Davide; Benini, Luca

    2015-05-01

    Monitoring current and voltage waveforms is fundamental to assess the power consumption of a system and to improve its energy efficiency. In this paper we present a smart meter for power consumption which does not need any electrical contact with the load or its conductors, and which can measure both current and voltage. Power metering becomes easier and safer and it is also self-sustainable because an energy harvesting module based on inductive coupling powers the entire device from the output of the current sensor. A low cost 32-bit wireless CPU architecture is used for data filtering and processing, while a wireless transceiver sends data via the IEEE 802.15.4 standard. We describe in detail the innovative contact-less voltage measurement system, which is based on capacitive coupling and on an algorithm that exploits two pre-processing channels. The system self-calibrates to perform precise measurements regardless the cable type. Experimental results demonstrate accuracy in comparison with commercial high-cost instruments, showing negligible deviations.

  5. Modeling and discussion of threshold voltage for a multi-floating gate FET pH sensor

    Institute of Scientific and Technical Information of China (English)

    Shi Zhaoxia; Zhu Dazhong

    2009-01-01

    Research into new pH sensors fabricated by the standard CMOS process is currently a hot topic. The new pH sensing multi-floating gate field effect transistor is found to have a very large threshold voltage, which is different from the normal ion-sensitive field effect transistor. After analyzing all the interface layers of the structure, a new sensitive model based on the Gauss theorem and the charge neutrality principle is created in this paper. According to the model, the charge trapped on the multi-floating gate during the process and the thickness of the sensitive layer are the main causes of the large threshold voltage. From this model, it is also found that removing the charge on the multi-floating gate is an effective way to decrease the threshold voltage. The test results for three different standard pH buffer solutions show the correctness of the model and point the way to solve the large threshold problem.

  6. Surface expression and channel function of TRPM8 are cooperatively controlled by transmembrane segments S3 and S4.

    Science.gov (United States)

    Kühn, Frank J P; Winking, Mathis; Kühn, Cornelia; Hoffmann, Daniel C; Lückhoff, Andreas

    2013-11-01

    TRPM8 is a voltage-dependent cation channel additionally gated by cold temperatures, menthol, and icilin. Stimulation by the chemical agonists is at least in part mediated by a conserved sequence motif in transmembrane segment S3. Based on molecular dynamics simulation studies for TRPM8 a gating model was recently developed which predicts a direct electrostatic interaction between S3 and S4. Here, we performed charge reversal mutations to pinpoint possible interactions of the putative S4 voltage sensor with S3. The charge reversals R842D, R842E, and D835R in S4 prevented channel glycosylation and function, indicating a deficient insertion into the plasma membrane. The mutations R842D and R842E were specifically rescued by the reciprocal charge reversal D802R in S3. The alternative charge reversal in S3, D796R, failed to compensate for the dysfunction of the mutants R842D and R842E. Remarkably, the double charge reversal mutants R842D + D802R and R842E + D802R retained intrinsic voltage-sensitivity, although the critical voltage sensor arginine was substituted by a negatively charged residue. Likewise, the insertion of three additional positively charged residues into S4 did not crucially change the voltage-sensitivity of TRPM8 but abolished the sensitivity to icilin. We conclude that S4 does not play a separate role for the gating of TRPM8. Instead, the cooperation with the adjacent segment S3 and the combined charges in these two segments is of general importance for both channel maturation and channel function. This mechanism distinguishes TRPM8 from other voltage-dependent cation channels within and outside the TRP family.

  7. Profile structures of the voltage-sensor domain and the voltage-gated K+-channel vectorially oriented in a single phospholipid bilayer membrane at the solid-vapor and solid-liquid interfaces determined by x-ray interferometry

    Science.gov (United States)

    Gupta, S.; Liu, J.; Strzalka, J.; Blasie, J. K.

    2011-09-01

    One subunit of the prokaryotic voltage-gated potassium ion channel from Aeropyrum pernix (KvAP) is comprised of six transmembrane α helices, of which S1-S4 form the voltage-sensor domain (VSD) and S5 and S6 contribute to the pore domain (PD) of the functional homotetramer. However, the mechanism of electromechanical coupling interconverting the closed-to-open (i.e., nonconducting-to-K+-conducting) states remains undetermined. Here, we have vectorially oriented the detergent (OG)-solubilized VSD in single monolayers by two independent approaches, namely “directed-assembly” and “self-assembly,” to achieve a high in-plane density. Both utilize Ni coordination chemistry to tether the protein to an alkylated inorganic surface via its C-terminal His6 tag. Subsequently, the detergent is replaced by phospholipid (POPC) via exchange, intended to reconstitute a phospholipid bilayer environment for the protein. X-ray interferometry, in which interference with a multilayer reference structure is used to both enhance and phase the specular x-ray reflectivity from the tethered single membrane, was used to determine directly the electron density profile structures of the VSD protein solvated by detergent versus phospholipid, and with either a moist He (moderate hydration) or bulk aqueous buffer (high hydration) environment to preserve a native structure conformation. Difference electron density profiles, with respect to the multilayer substrate itself, for the VSD-OG monolayer and VSD-POPC membranes at both the solid-vapor and solid-liquid interfaces, reveal the profile structures of the VSD protein dominating these profiles and further indicate a successful reconstitution of a lipid bilayer environment. The self-assembly approach was similarly extended to the intact full-length KvAP channel for comparison. The spatial extent and asymmetry in the profile structures of both proteins confirm their unidirectional vectorial orientation within the reconstituted membrane and

  8. Applications of passive remote surface acoustic wave sensors in high-voltage systems; Einsatz von passiven funkabfragbaren Oberflaechenwellensensoren in der elektrischen Energietechnik

    Energy Technology Data Exchange (ETDEWEB)

    Teminova, R.

    2007-06-29

    Passive remote Surface Acoustic Wave (SAW) sensors have been applied e.g. as temperature, pressure or torque sensors. Their important advantages over standard methods are their passive operating principle, which allows operation without any power supply, as well as the wireless high-frequency signal transmission over distances up to about 10..15 m even through (non metallic) housings. These properties of SAW sensors particularly qualify them for applications in high voltage operational equipment. First experience was gained in a long time field test of surge arrester monitoring based on SAW temperature sensors in a German high-voltage substation. Now, this system has been further developed at Darmstadt University of Technology for other applications, the first of them being an overhead line (OHL) conductor temperature measurement, the second one a temperature monitoring system for of high-voltage disconnectors. After designing and building the sensors, extensive laboratory tests were carried out applying high-voltage, high-current and thermal stress in order to approve the suitability for the intended application. All these tests confirmed the assumption that SAW sensors, due to their passive working principle, are not affected at all by any kind of electrical, magnetic or thermal stress that may occur during service. The complete temperature sensor consists of three parts: a sensor chip, an antenna which receives and transmits the signal from and to the radar unit and a body for installation and for protection against environmental impact. One must find a good compromise between optimizing of thermal, dielectric and high-frequency characteristics and at the same time taking into consideration a simple installation. These requirements on the SAW sensors turned out to be difficult to coordinate. To achieve a high measuring precision is especially difficult. First, a new sensor for OHL application was developed. The OHL conductor temperature sensor had been optimized

  9. High voltage monolithic active pixel sensors for the PANDA luminosity detector

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Tobias; Feldbauer, Florian; Jasinski, Prometeusz; Leithoff, Heinrich; Motzko, Christof; Fritsch, Miriam [Helmholtz-Institut Mainz and Institut fuer Kernphysik, Universitaet Mainz (Germany); Collaboration: PANDA-Collaboration

    2014-07-01

    The PANDA-Experiment will be part of the new FAIR accelerator center at Darmstadt, Germany. It is a fixed target experiment using a antiproton beam with very high resolution for precision measurements. For a variety of measurements like energy-scans the precise determination of the luminosity is needed. The luminosity detector will determine the luminosity by measuring the angular distribution of elastically scattered antiprotons very close to the beam axis (3-8 mrad). To reconstruct antiproton tracks four layers of thinned silicon sensors with smart pixel readout on chip (HV-MAPS) will be used. Those sensors are currently under development by the Mu3e-collaboration. In the talk the concept of the luminosity measurement is shortly introduced before a summary of the status of HV-MAP prototypes and recent test beam results are presented.

  10. Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors.

    Science.gov (United States)

    Lee, Sungmoo; Piao, Hong Hua; Sepheri-Rad, Masoud; Jung, Arong; Sung, Uhna; Song, Yoon-Kyu; Baker, Bradley J

    2016-02-04

    Genetically encoded voltage indicators (GEVIs) have improved to the point where they are beginning to be useful for in vivo recordings. While the ultimate goal is to image neuronal activity in vivo, one must be able to image activity of a single cell to ensure successful in vivo preparations. This procedure will describe how to image membrane potential in a single cell to provide a foundation to eventually image in vivo. Here we describe methods for imaging GEVIs consisting of a voltage-sensing domain fused to either a single fluorescent protein (FP) or two fluorescent proteins capable of Förster resonance energy transfer (FRET) in vitro. Using an image splitter enables the projection of images created by two different wavelengths onto the same charge-coupled device (CCD) camera simultaneously. The image splitter positions a second filter cube in the light path. This second filter cube consists of a dichroic and two emission filters to separate the donor and acceptor fluorescent wavelengths depending on the FPs of the GEVI. This setup enables the simultaneous recording of both the acceptor and donor fluorescent partners while the membrane potential is manipulated via whole cell patch clamp configuration. When using a GEVI consisting of a single FP, the second filter cube can be removed allowing the mirrors in the image splitter to project a single image onto the CCD camera.

  11. Two-photon scanning microscopy of in vivo sensory responses of cortical neurons genetically encoded with a fluorescent voltage sensor in rat

    Directory of Open Access Journals (Sweden)

    Kurt F Ahrens

    2012-03-01

    Full Text Available A fluorescent voltage sensor protein Flare was created from a Kv1.4 potassium channel with YFP situated to report voltage-induced conformational changes in vivo. The RNA virus Sindbis introduced Flare into neurons in the binocular visual crescent in rat. Injection sites were selected based on intrinsic optical imaging. Expression of Flare occurred in the cell bodies and dendritic processes. Neurons imaged in vivo using two-photon scanning microscopy typically revealed the soma best, discernable against the background labeling of the neuropil. Somatic fluorescence changes were correlated with flashed visual stimuli; however, averaging was essential to observe these changes. This study demonstrates that the genetic modification of single neurons to express a fluorescent voltage sensor can be used to assess neuronal activity in vivo.

  12. Two-photon scanning microscopy of in vivo sensory responses of cortical neurons genetically encoded with a fluorescent voltage sensor in rat

    Science.gov (United States)

    Ahrens, Kurt F.; Heider, Barbara; Lee, Hanson; Isacoff, Ehud Y.; Siegel, Ralph M.

    2012-01-01

    A fluorescent voltage sensor protein “Flare” was created from a Kv1.4 potassium channel with YFP situated to report voltage-induced conformational changes in vivo. The RNA virus Sindbis introduced Flare into neurons in the binocular region of visual cortex in rat. Injection sites were selected based on intrinsic optical imaging. Expression of Flare occurred in the cell bodies and dendritic processes. Neurons imaged in vivo using two-photon scanning microscopy typically revealed the soma best, discernable against the background labeling of the neuropil. Somatic fluorescence changes were correlated with flashed visual stimuli; however, averaging was essential to observe these changes. This study demonstrates that the genetic modification of single neurons to express a fluorescent voltage sensor can be used to assess neuronal activity in vivo. PMID:22461770

  13. Impact of field limiting ring technique on breakdown voltage of irradiated Si sensors

    CERN Document Server

    Bhardwaj, Ashutosh; Jha Manoj, Kr; Kumar, Ashish; Ranjan, Kirti; Shivpuri, RK; Srivastava-Ajay, K

    2003-01-01

    The very intense radiation environment of high luminosity future colliding beam experiments (like LHC) makes radiation hardness the most important issue for Si detectors. One of the central issues concerning all LHC experiments is the breakdown performance of these detectors. The major macroscopic effect of radiation damage in determining the viability of long-term operation of Si sensors is the change in effective charge carrier concentration (N //e//f//f), leading to type-inversion. Floating field limiting guard rings have been established as means of improving the breakdown performance of Si detectors. In this work the usefulness of the guard rings in improving the breakdown performance of detectors after type-inversion has been studied. Simulations are carried out to study the effect of change in N//e//f//f on the breakdown performance of optimized guard ring structure using two dimensional device simulation program, TMA- MEDICI. Detailed calculations using Hamburg Model have allowed the parameterization ...

  14. Impact of field limiting ring technique on breakdown voltage of irradiated Si sensors

    CERN Document Server

    Bhardwaj, A; Namrata, S; Chatterji, S; Srivastava-Ajay, K; Kumar, A; Jha, Manoj Kumar; Shivpuri, R K

    2004-01-01

    The very intense radiation environment of high luminosity future colliding beam experiments (like LHC) makes radiation hardness the most important issue for Si detectors. One of the central issues concerning all LHC experiments is the breakdown performance of these detectors. The major macroscopic effect of radiation damage in determining the viability of long-term operation of Si sensors is the change in effective charge carrier concentration (N/sub eff/), leading to type-inversion. Floating field limiting guard rings have been established as means of improving the breakdown performance of Si detectors. In this work the usefulness of the guard rings in improving the breakdown performance of detectors after type-inversion has been studied. Simulations are carried out to study the effect of change in N/sub eff/ on the breakdown performance of optimized guard ring structure using two dimensional device simulation program, TMA- MEDICI. Detailed calculations using Hamburg Model have allowed the parameterization o...

  15. Application of HFCT and UHF Sensors in On-Line Partial Discharge Measurements for Insulation Diagnosis of High Voltage Equipment

    Directory of Open Access Journals (Sweden)

    Fernando Álvarez

    2015-03-01

    Full Text Available Partial discharge (PD measurements provide valuable information for assessing the condition of high voltage (HV insulation systems, contributing to their quality assurance. Different PD measuring techniques have been developed in the last years specially designed to perform on-line measurements. Non-conventional PD methods operating in high frequency bands are usually used when this type of tests are carried out. In PD measurements the signal acquisition, the subsequent signal processing and the capability to obtain an accurate diagnosis are conditioned by the selection of a suitable detection technique and by the implementation of effective signal processing tools. This paper proposes an optimized electromagnetic detection method based on the combined use of wideband PD sensors for measurements performed in the HF and UHF frequency ranges, together with the implementation of powerful processing tools. The effectiveness of the measuring techniques proposed is demonstrated through an example, where several PD sources are measured simultaneously in a HV installation consisting of a cable system connected by a plug-in terminal to a gas insulated substation (GIS compartment.

  16. A DC-Link Voltage Self-Balance Method for a Diode-Clamped Modular Multilevel Converter With Minimum Number of Voltage Sensors

    DEFF Research Database (Denmark)

    Gao, Congzhe; Jiang, Xinjian; Li, Yongdong

    2013-01-01

    Voltage balance issue of dc-link capacitors is very important for applications of a cascade multilevel converter or a modular multilevel converter. In this paper, a novel diode-clamped modular multilevel converter (DCM2C) topology is proposed and a power feedback control method is developed...

  17. Applications of passive remote surface acoustic wave sensors in high-voltage systems; Einsatz von passiven funkabfragbaren Oberflaechenwellensensoren in der elektrischen Energietechnik

    Energy Technology Data Exchange (ETDEWEB)

    Teminova, R.

    2007-06-29

    Passive remote Surface Acoustic Wave (SAW) sensors have been applied e.g. as temperature, pressure or torque sensors. Their important advantages over standard methods are their passive operating principle, which allows operation without any power supply, as well as the wireless high-frequency signal transmission over distances up to about 10..15 m even through (non metallic) housings. These properties of SAW sensors particularly qualify them for applications in high voltage operational equipment. First experience was gained in a long time field test of surge arrester monitoring based on SAW temperature sensors in a German high-voltage substation. Now, this system has been further developed at Darmstadt University of Technology for other applications, the first of them being an overhead line (OHL) conductor temperature measurement, the second one a temperature monitoring system for of high-voltage disconnectors. After designing and building the sensors, extensive laboratory tests were carried out applying high-voltage, high-current and thermal stress in order to approve the suitability for the intended application. All these tests confirmed the assumption that SAW sensors, due to their passive working principle, are not affected at all by any kind of electrical, magnetic or thermal stress that may occur during service. The complete temperature sensor consists of three parts: a sensor chip, an antenna which receives and transmits the signal from and to the radar unit and a body for installation and for protection against environmental impact. One must find a good compromise between optimizing of thermal, dielectric and high-frequency characteristics and at the same time taking into consideration a simple installation. These requirements on the SAW sensors turned out to be difficult to coordinate. To achieve a high measuring precision is especially difficult. First, a new sensor for OHL application was developed. The OHL conductor temperature sensor had been optimized

  18. A limited 4 Å radial displacement of the S4-S5 linker is sufficient for internal gate closing in Kv channels.

    Science.gov (United States)

    Faure, Élise; Starek, Greg; McGuire, Hugo; Bernèche, Simon; Blunck, Rikard

    2012-11-16

    Voltage-gated ion channels are responsible for the generation of action potentials in our nervous system. Conformational rearrangements in their voltage sensor domains in response to changes of the membrane potential control pore opening and thus ion conduction. Crystal structures of the open channel in combination with a wealth of biophysical data and molecular dynamics simulations led to a consensus on the voltage sensor movement. However, the coupling between voltage sensor movement and pore opening, the electromechanical coupling, occurs at the cytosolic face of the channel, from where no structural information is available yet. In particular, the question how far the cytosolic pore gate has to close to prevent ion conduction remains controversial. In cells, spectroscopic methods are hindered because labeling of internal sites remains difficult, whereas liposomes or detergent solutions containing purified ion channels lack voltage control. Here, to overcome these problems, we controlled the state of the channel by varying the lipid environment. This way, we directly measured the position of the S4-S5 linker in both the open and the closed state of a prokaryotic Kv channel (KvAP) in a lipid environment using Lanthanide-based resonance energy transfer. We were able to reconstruct the movement of the covalent link between the voltage sensor and the pore domain and used this information as restraints for molecular dynamics simulations of the closed state structure. We found that a small decrease of the pore radius of about 3-4 Å is sufficient to prevent ion permeation through the pore.

  19. mTORC1 Is a Local, Postsynaptic Voltage Sensor Regulated by Positive and Negative Feedback Pathways

    Directory of Open Access Journals (Sweden)

    Farr Niere

    2017-05-01

    Full Text Available The mammalian/mechanistic target of rapamycin complex 1 (mTORC1 serves as a regulator of mRNA translation. Recent studies suggest that mTORC1 may also serve as a local, voltage sensor in the postsynaptic region of neurons. Considering biochemical, bioinformatics and imaging data, we hypothesize that the activity state of mTORC1 dynamically regulates local membrane potential by promoting and repressing protein synthesis of select mRNAs. Our hypothesis suggests that mTORC1 uses positive and negative feedback pathways, in a branch-specific manner, to maintain neuronal excitability within an optimal range. In some dendritic branches, mTORC1 activity oscillates between the “On” and “Off” states. We define this as negative feedback. In contrast, positive feedback is defined as the pathway that leads to a prolonged depolarized or hyperpolarized resting membrane potential, whereby mTORC1 activity is constitutively on or off, respectively. We propose that inactivation of mTORC1 increases the expression of voltage-gated potassium alpha (Kv1.1 and 1.2 and beta (Kvβ2 subunits, ensuring that the membrane resets to its resting membrane potential after experiencing increased synaptic activity. In turn, reduced mTORC1 activity increases the protein expression of syntaxin-1A and promotes the surface expression of the ionotropic glutamate receptor N-methyl-D-aspartate (NMDA-type subunit 1 (GluN1 that facilitates increased calcium entry to turn mTORC1 back on. Under conditions such as learning and memory, mTORC1 activity is required to be high for longer periods of time. Thus, the arm of the pathway that promotes syntaxin-1A and Kv1 protein synthesis will be repressed. Moreover, dendritic branches that have low mTORC1 activity with increased Kv expression would balance dendrites with constitutively high mTORC1 activity, allowing for the neuron to maintain its overall activity level within an ideal operating range. Finally, such a model suggests that

  20. Probing S4 and S5 segment proximity in mammalian hyperpolarization-activated HCN channels by disulfide bridging and Cd2+ coordination.

    Science.gov (United States)

    Bell, Damian C; Turbendian, Harma K; Valley, Matthew T; Zhou, Lei; Riley, John H; Siegelbaum, Steven A; Tibbs, Gareth R

    2009-06-01

    We explored the structural basis of voltage sensing in the HCN1 hyperpolarization-activated cyclic nucleotide-gated cation channel by examining the relative orientation of the voltage sensor and pore domains. The opening of channels engineered to contain single cysteine residues at the extracellular ends of the voltage-sensing S4 (V246C) and pore-forming S5 (C303) domains is inhibited by formation of disulfide or cysteine:Cd(2+) bonds. As Cd(2+) coordination is promoted by depolarization, the S4-S5 interaction occurs preferentially in the closed state. The failure of oxidation to catalyze dimer formation, as assayed by Western blotting, indicates the V246C:C303 interaction occurs within a subunit. Intriguingly, a similar interaction has been observed in depolarization-activated Shaker voltage-dependent potassium (Kv) channels at depolarized potentials but such an intrasubunit interaction is inconsistent with the X-ray crystal structure of Kv1.2, wherein S4 approaches S5 of an adjacent subunit. These findings suggest channels of opposite voltage-sensing polarity adopt a conserved S4-S5 orientation in the depolarized state that is distinct from that trapped upon crystallization.

  1. Relationship between CO2 Sensor Voltage Response and Phase Equilibrium of Solid Electrolyte Na, K-β/β"-Al2O3

    Institute of Scientific and Technical Information of China (English)

    J.H. YANG; H.N(a)fe; F. Aldinger; D.S. YAN

    2003-01-01

    A type of CO2 sensor based on oxygen concentration cell was designed as following: Cell I: Pt | Au, O2,CO2|Na2CO3(Au)|NKBA(Au)|YSZ|O2, CO2|Pt or Cell Ⅱ: Pt|Au, O2, CO2|K2CO3(Au)|NKBA(Au)|YSZ|O2, CO2|Pt.(Na,K-β/β″-Al2O3 is named by NKBA). The sensor signal is consistent with the Nernstian slope within the region ofphase equilibrium for Na, K-β/β"-Al2O3 material. The relationship between CO2 sensor voltage response and phaseequilibrium of solid electrolyte Na, K-β/β-Al2O3 is discussed in this paper.

  2. The S4-S5 linker acts as a signal integrator for HERG K+ channel activation and deactivation gating.

    Science.gov (United States)

    Ng, Chai Ann; Perry, Matthew D; Tan, Peter S; Hill, Adam P; Kuchel, Philip W; Vandenberg, Jamie I

    2012-01-01

    Human ether-à-go-go-related gene (hERG) K(+) channels have unusual gating kinetics. Characterised by slow activation/deactivation but rapid inactivation/recovery from inactivation, the unique gating kinetics underlie the central role hERG channels play in cardiac repolarisation. The slow activation and deactivation kinetics are regulated in part by the S4-S5 linker, which couples movement of the voltage sensor domain to opening of the activation gate at the distal end of the inner helix of the pore domain. It has also been suggested that cytosolic domains may interact with the S4-S5 linker to regulate activation and deactivation kinetics. Here, we show that the solution structure of a peptide corresponding to the S4-S5 linker of hERG contains an amphipathic helix. The effects of mutations at the majority of residues in the S4-S5 linker of hERG were consistent with the previously identified role in coupling voltage sensor movement to the activation gate. However, mutations to Ser543, Tyr545, Gly546 and Ala548 had more complex phenotypes indicating that these residues are involved in additional interactions. We propose a model in which the S4-S5 linker, in addition to coupling VSD movement to the activation gate, also contributes to interactions that stabilise the closed state and a separate set of interactions that stabilise the open state. The S4-S5 linker therefore acts as a signal integrator and plays a crucial role in the slow deactivation kinetics of the channel.

  3. Energetic role of the paddle motif in voltage gating of Shaker K(+) channels.

    Science.gov (United States)

    Xu, Yanping; Ramu, Yajamana; Shin, Hyeon-Gyu; Yamakaze, Jayden; Lu, Zhe

    2013-05-01

    Voltage-gated ion channels underlie rapid electric signaling in excitable cells. Electrophysiological studies have established that the N-terminal half of the fourth transmembrane segment ((NT)S4) of these channels is the primary voltage sensor, whereas crystallographic studies have shown that (NT)S4 is not located within a proteinaceous pore. Rather, (NT)S4 and the C-terminal half of S3 ((CT)S3 or S3b) form a helix-turn-helix motif, termed the voltage-sensor paddle. This unexpected structural finding raises two fundamental questions: does the paddle motif also exist in voltage-gated channels in a biological membrane, and, if so, what is its function in voltage gating? Here, we provide evidence that the paddle motif exists in the open state of Drosophila Shaker voltage-gated K(+) channels expressed in Xenopus oocytes and that (CT)S3 acts as an extracellular hydrophobic 'stabilizer' for (NT)S4, thus biasing the gating chemical equilibrium toward the open state.

  4. Conserved residues within the putative S4-S5 region serve distinct functions among thermosensitive vanilloid transient receptor potential (TRPV) channels.

    Science.gov (United States)

    Boukalova, Stepana; Marsakova, Lenka; Teisinger, Jan; Vlachova, Viktorie

    2010-12-31

    The vanilloid transient receptor potential channel TRPV1 is a tetrameric six-transmembrane segment (S1-S6) channel that can be synergistically activated by various proalgesic agents such as capsaicin, protons, heat, or highly depolarizing voltages, and also by 2-aminoethoxydiphenyl borate (2-APB), a common activator of the related thermally gated vanilloid TRP channels TRPV1, TRPV2, and TRPV3. In these channels, the conserved charged residues in the intracellular S4-S5 region have been proposed to constitute part of a voltage sensor that acts in concert with other stimuli to regulate channel activation. The molecular basis of this gating event is poorly understood. We mutated charged residues all along the S4 and the S4-S5 linker of TRPV1 and identified four potential voltage-sensing residues (Arg(557), Glu(570), Asp(576), and Arg(579)) that, when specifically mutated, altered the functionality of the channel with respect to voltage, capsaicin, heat, 2-APB, and/or their interactions in different ways. The nonfunctional charge-reversing mutations R557E and R579E were partially rescued by the charge-swapping mutations R557E/E570R and D576R/R579E, indicating that electrostatic interactions contribute to allosteric coupling between the voltage-, temperature- and capsaicin-dependent activation mechanisms. The mutant K571E was normal in all aspects of TRPV1 activation except for 2-APB, revealing the specific role of Lys(571) in chemical sensitivity. Surprisingly, substitutions at homologous residues in TRPV2 or TRPV3 had no effect on temperature- and 2-APB-induced activity. Thus, the charged residues in S4 and the S4-S5 linker contribute to voltage sensing in TRPV1 and, despite their highly conserved nature, regulate the temperature and chemical gating in the various TRPV channels in different ways.

  5. Evidence for intersubunit interactions between S4 and S5 transmembrane segments of the Shaker potassium channel.

    Science.gov (United States)

    Neale, Edward J; Elliott, David J S; Hunter, Malcolm; Sivaprasadarao, Asipu

    2003-08-01

    Voltage-gated potassium channels are transmembrane proteins made up of four subunits, each comprising six transmembrane (S1-S6) segments. S1-S4 form the voltage-sensing domain and S5-S6 the pore domain with its central pore. The sensor domain detects membrane depolarization and transmits the signal to the activation gates situated in the pore domain, thereby leading to channel opening. An understanding of the mechanism by which the sensor communicates the signal to the pore requires knowledge of the structure of the interface between the voltage-sensing and pore domains. Toward this end, we have introduced single cysteine mutations into the extracellular end of S4 (positions 356 and 357) in conjunction with a cysteine in S5 (position 418) of the Shaker channel and expressed the mutants in Xenopus oocytes. We then examined the propensity of each pair of engineered cysteines to form a metal bridge or a disulfide bridge, respectively, by examining the effect of Cd2+ ions and copper phenanthroline on the K+ conductance of a whole oocyte. Both reagents reduced currents through the S357C,E418C double mutant channel, presumably by restricting the movements necessary for coupling the voltage-sensing function to pore opening. This inhibitory effect was seen in the closed state of the channel and with heteromers composed of S357C and E418C single mutant subunits; no effect was seen with homomers of any of the single mutant channels. These data indicate that the extracellular end of S4 lies in close proximity to the extracellular end of the S5 of the neighboring subunit in closed channels.

  6. Impact of metal overhang and guard ring techniques on breakdown voltage of Si strip sensors - 2003 IEEE nuclear science symposium, medical imaging conference, and workshop of room-temperature semiconductor detectors

    CERN Document Server

    Ranjan, K; Namrata, S; Chatterji, S; Srivastava-Ajay, K; Kumar, A; Jha, Manoj Kumar; Shivpuri, R K

    2004-01-01

    The importance of Si sensors in high-energy physics (HEP) experiments can hardly be overemphasized. However, the high luminosity and the high radiation level in the future HEP experiments, like Large Hadron Collider (LHC), has posed a serious challenge to the fabrication of Si detectors. For the safe operation over the full LHC lifetime, detectors are required to sustain very high voltage operation, well exceeding the bias voltage needed to full deplete the heavily irradiated Si sensors. Thus, the main effort in the development of Si sensors is concentrated on a design that avoids p-n junction breakdown at operational biases. Among various proposed techniques, Field-limiting Ring (FLR) (or guard ring) and Metal-Overhang (MO) are technologically simple and are suitable for vertical devices. Since high-voltage planar Si junctions are of great importance in the HEP experiments, it is very interesting to compare these two aforementioned techniques for achieving the maximum breakdown voltage under optimal conditio...

  7. Development and Application of a Wireless Sensor for Space Charge Density Measurement in an Ultra-High-Voltage, Direct-Current Environment.

    Science.gov (United States)

    Xin, Encheng; Ju, Yong; Yuan, Haiwen

    2016-10-20

    A space charge density wireless measurement system based on the idea of distributed measurement is proposed for collecting and monitoring the space charge density in an ultra-high-voltage direct-current (UHVDC) environment. The proposed system architecture is composed of a number of wireless nodes connected with space charge density sensors and a base station. The space charge density sensor based on atmospheric ion counter method is elaborated and developed, and the ARM microprocessor and Zigbee radio frequency module are applied. The wireless network communication quality and the relationship between energy consumption and transmission distance in the complicated electromagnetic environment is tested. Based on the experimental results, the proposed measurement system demonstrates that it can adapt to the complex electromagnetic environment under the UHVDC transmission lines and can accurately measure the space charge density.

  8. Wireless Power Supply via Coupled Magnetic Resonance for on-line Monitoring Wireless Sensor of High-voltage Electrical Equipment

    DEFF Research Database (Denmark)

    Xingkui, Mao; Qisheng, Huang; Yudi, Xiao

    2016-01-01

    , in this paper, the wireless power supply via coupled magnetic resonance (MR-WPS) is proposed for powering the wireless sensor and the associated wireless sensor solution is also proposed. The key specifications of the MR-WPS working in switchgear cabinet with a harsh operation environment are analyzed...

  9. Fibre-optic sensors for partial discharge-generated ultrasound in elastomeric high-voltage insulation materials

    Science.gov (United States)

    Rohwetter, P.; Habel, W.

    2013-05-01

    Recent progress in the development of ultrasonic fibre-optic sensors for detecting acoustic emission from partial discharge in elastomeric insulations is presented. These sensors are an important part of a proposed comprehensive scheme for the fibre-optic monitoring of cable accessories. After specifying the underlying design goals the improved fibre-optic sensor design is outlined. It is experimentally shown that it offers about ten-fold improvement over a previously investigated resonant cantilever-type design in terms of detection limit, making it competitive with conventional piezoelectric transducers, however with the added compatibility with strong electrical fields and electromagnetically noisy environments.

  10. CMOS temperature sensor using a resistively degenerated common-source amplifier biased by an adjustable proportional-to-absolute-temperature voltage

    Science.gov (United States)

    Wang, Ruey-Lue; Fu, Chien-Cheng; Yu, Chi; Hao, Yi-Fan; Shi, Jian-Liang; Lin, Chen-Fu; Liao, Hsin-Hao; Tsai, Hann-Huei; Juang, Ying-Zong

    2014-01-01

    A high-linearity CMOS temperature sensor with pulse output is presented. The temperature core is a resistively degenerated common-source amplifier which gate is biased by a proportional-to-absolute-temperature (PTAT) voltage generator. The source resistor is made of polysilicon which resistance has a PTAT characteristic. The current flowing through the resistor exhibits a PTAT characteristic with high linearity of 99.99% at least for a temperature range from 0 to 125 °C. The PTAT voltage generator can be adjusted by a bias voltage Vb and hence the PTAT current can also be adjusted by the Vb. The PTAT current is mirrored to an added current controlled oscillator which output pulse frequencies also exhibit a PTAT characteristic. For the chip using the 0.35 µm process, the plots of measured pulse frequencies against temperature exhibit the sensitivity of 2.30 to 2.24 kHz/°C with linearity of more than 99.99% at the Vb of 1 to 1.2 V.

  11. The concerted contribution of the S4-S5 linker and the S6 segment to the modulation of a Kv channel by 1-alkanols.

    Science.gov (United States)

    Bhattacharji, Aditya; Kaplan, Benjamin; Harris, Thanawath; Qu, Xiaoguang; Germann, Markus W; Covarrubias, Manuel

    2006-11-01

    Gating of voltage-gated K(+) channels (K(v) channels) depends on the electromechanical coupling between the voltage sensor and activation gate. The main activation gate of K(v) channels involves the COOH-terminal section of the S6 segment (S6-b) and the S4-S5 linker at the intracellular mouth of the pore. In this study, we have expanded our earlier work to probe the concerted contribution of these regions to the putative amphipathic 1-alkanol site in the Shaw2 K(+) channel. In the S4-S5 linker, we found a direct energetic correlation between alpha-helical propensity and the inhibition of the Shaw2 channel by 1-butanol. Spectroscopic structural analyses of the S4-S5 linker supported this correlation. Furthermore, the analysis of chimeric Shaw2 and K(v)3.4 channels that exchanged their corresponding S4-S5 linkers showed that the potentiation induced by 1-butanol depends on the combination of a single mutation in the S6 PVPV motif (PVAV) and the presence of the Shaw2 S4-S5 linker. Then, using tandem-heterodimer subunits, we determined that this potentiation also depends on the number of S4-S5 linkers and PVAV mutations in the K(v) channel tetramer. Consistent with the critical contribution of the Shaw2 S4-S5 linker, the equivalent PVAV mutation in certain mammalian K(v) channels with divergent S4-S5 linkers conferred weak potentiation by 1-butanol. Overall, these results suggest that 1-alkanol action in Shaw2 channels depends on interactions involving the S4-S5 linker and the S6-b segment. Therefore, we propose that amphiphilic general anesthetic agents such as 1-alkanols may modulate gating of the Shaw2 K(+) channel by an interaction with its activation gate.

  12. Ion permeation and block of the gating pore in the voltage sensor of NaV1.4 channels with hypokalemic periodic paralysis mutations.

    Science.gov (United States)

    Sokolov, Stanislav; Scheuer, Todd; Catterall, William A

    2010-08-01

    Hypokalemic periodic paralysis and normokalemic periodic paralysis are caused by mutations of the gating charge-carrying arginine residues in skeletal muscle Na(V)1.4 channels, which induce gating pore current through the mutant voltage sensor domains. Inward sodium currents through the gating pore of mutant R666G are only approximately 1% of central pore current, but substitution of guanidine for sodium in the extracellular solution increases their size by 13- +/- 2-fold. Ethylguanidine is permeant through the R666G gating pore at physiological membrane potentials but blocks the gating pore at hyperpolarized potentials. Guanidine is also highly permeant through the proton-selective gating pore formed by the mutant R666H. Gating pore current conducted by the R666G mutant is blocked by divalent cations such as Ba(2+) and Zn(2+) in a voltage-dependent manner. The affinity for voltage-dependent block of gating pore current by Ba(2+) and Zn(2+) is increased at more negative holding potentials. The apparent dissociation constant (K(d)) values for Zn(2+) block for test pulses to -160 mV are 650 +/- 150 microM, 360 +/- 70 microM, and 95.6 +/- 11 microM at holding potentials of 0 mV, -80 mV, and -120 mV, respectively. Gating pore current is blocked by trivalent cations, but in a nearly voltage-independent manner, with an apparent K(d) for Gd(3+) of 238 +/- 14 microM at -80 mV. To test whether these periodic paralyses might be treated by blocking gating pore current, we screened several aromatic and aliphatic guanidine derivatives and found that 1-(2,4-xylyl)guanidinium can block gating pore current in the millimolar concentration range without affecting normal Na(V)1.4 channel function. Together, our results demonstrate unique permeability of guanidine through Na(V)1.4 gating pores, define voltage-dependent and voltage-independent block by divalent and trivalent cations, respectively, and provide initial support for the concept that guanidine-based gating pore blockers

  13. Membrane-perturbing properties of two Arg-rich paddle domains from voltage-gated sensors in the KvAP and HsapBK K(+) channels.

    Science.gov (United States)

    Unnerståle, Sofia; Madani, Fatemeh; Gräslund, Astrid; Mäler, Lena

    2012-05-15

    Voltage-gated K(+) channels are gated by displacement of basic residues located in the S4 helix that together with a part of the S3 helix, S3b, forms a "paddle" domain, whose position is altered by changes in the membrane potential modulating the open probability of the channel. Here, interactions between two paddle domains, KvAPp from the K(v) channel from Aeropyrum pernix and HsapBKp from the BK channel from Homo sapiens, and membrane models have been studied by spectroscopy. We show that both paddle domains induce calcein leakage in large unilamellar vesicles, and we suggest that this leakage represents a general thinning of the bilayer, making movement of the whole paddle domain plausible. The fact that HsapBKp induces more leakage than KvAPp may be explained by the presence of a Trp residue in HsapBKp. Trp residues generally promote localization to the hydrophilic-hydrophobic interface and disturb tight packing. In magnetically aligned bicelles, KvAPp increases the level of order along the whole acyl chain, while HsapBKp affects the morphology, also indicating that KvAPp adapts more to the lipid environment. Nuclear magnetic resonance (NMR) relaxation measurements for HsapBKp show that overall the sequence has anisotropic motions. The S4 helix is well-structured with restricted local motion, while the turn between S4 and S3b is more flexible and undergoes slow local motion. Our results indicate that the calcein leakage is related to the flexibility in this turn region. A possibility by which HsapBKp can undergo structural transitions is also shown by relaxation NMR, which may be important for the gating mechanism.

  14. A Disease Mutation Causing Episodic Ataxia Type I in the S1 Links Directly to the Voltage Sensor and the Selectivity Filter in Kv Channels.

    Science.gov (United States)

    Petitjean, Dimitri; Kalstrup, Tanja; Zhao, Juan; Blunck, Rikard

    2015-09-02

    The mutation F184C in Kv1.1 leads to development of episodic ataxia type I (EA1). Although the mutation has been said to alter activation kinetics and to lower expression, we show here that the underlying molecular mechanisms may be more complex. Although F184 is positioned in the "peripheral" S1 helix, it occupies a central position in the 3D fold. We show in cut-open oocyte voltage-clamp recordings of gating and ionic currents of the Shaker Kv channel expressed in Xenopus oocytes that F184 not only interacts directly with the gating charges of the S4, but also creates a functional link to the selectivity filter of the neighboring subunit. This link leads to impaired fast and slow inactivation. The effect on fast inactivation is of an allosteric nature considering that fast inactivation is caused by a linked cytosolic ball peptide. The extensive effects of F184C provide a new mechanism underlying EA. Episodic ataxia (EA) is an inherited disease that leads to occasional loss of motor control in combination with variable other symptoms such as vertigo or migraine. EA type I (EA1), studied here, is caused by mutations in a voltage-gated potassium channel that contributes to the generation of electrical signals in the brain. The mechanism by which mutations in voltage-gated potassium channels lead to EA is still unknown and there is no consistent pharmacological treatment. By studying in detail one disease-causing mutation in Kv1.1, we describe a novel molecular mechanism distinct from mechanisms described previously. This mechanism contributes to the understanding of potassium channel function in general and might lead to a better understanding of how EA develops. Copyright © 2015 the authors 0270-6474/15/3512198-09$15.00/0.

  15. PWM的整流器无交流电压传感器控制%Vector Control of PWM Rectifier without AC Voltage sensors

    Institute of Scientific and Technical Information of China (English)

    张宏杰

    2012-01-01

      针对采用虚拟磁链定向控制策略的PWM整流器无交流电压传感器控制中存在的由积分环节带来的一系列问题,将滑模观测器(SMO)应用于估测电网电压角度,利用饱和函数代替传统滑模观测器中的符号函数以削弱系统抖振,并对比分析了两种情况下等效控制信号的频谱图,仿真和实验结果表明,基于滑模观测器的PWM整流器具有良好的动静态响应和输入输出特性,验证了所提出的无交流电压传感器控制策略的有效性和准确性。%  To solve the problems caused by integer which were used in virtual flux oriented control of PWM rec⁃tifier without AC voltage sensors, a sliding mode observer (SMO) was designed to estimate grid voltage angle. This paper analyzes the principle, designs steps of SMO .and uses saturated function instead of symbols function in traditional sliding mode observer to weaken the system chattering. The paper also analyzes the equivalent con⁃trol signal spectrum diagram in the two cases. Simulation and experimental results show that PWM rectifier has a good dynamic/static response and input/output characteristics and verifies the validity and feasibility of the pro⁃posed AC voltage sensorless control strategy.

  16. A CAD investigation of metal-overhang on multiple guard ring design for high voltage operation of Si sensors

    Science.gov (United States)

    Bhardwaj, Ashutosh; Ranjan, Kirti; Namrata; Chatterji, Sudeep; Srivastava, Ajay K.; Shivpuri, R. K.

    2002-12-01

    The extension of Si detectors to the next generation high-energy physics experiments such as large hadron collider implies a reliable operation in high radiation environment which is by far the main technological challenge for these detectors. Multiple field limiting ring systems are well established as a means of protecting diffused junction from high voltage premature breakdown. Also, a spread of the Al metallization over the inter-cathodic field oxide sensibly lowers the electric field at the junction edges, thus, allowing for higher breakdown voltages. The purpose of this work is to combine the positive aspects of these two termination techniques with the aim of defining layouts and technological solutions suitable for the use of Si detectors in adverse radiation environment. An important feature is the potential distribution in the multi-guard ring structure, which depends on the bulk doping concentration, the oxide charge, the size of the gap between guard rings and the metal-overhang design. A systematic investigation on the breakdown performance is done by varying the physical and geometrical parameters such as width of overhang, guard ring spacing, junction depth and oxide charge. CAD tools are used for evaluating potential and electric field distributions within the device.

  17. Fluorescence-tracking of activation gating in human ERG channels reveals rapid S4 movement and slow pore opening.

    Directory of Open Access Journals (Sweden)

    Zeineb Es-Salah-Lamoureux

    Full Text Available BACKGROUND: hERG channels are physiologically important ion channels which mediate cardiac repolarization as a result of their unusual gating properties. These are very slow activation compared with other mammalian voltage-gated potassium channels, and extremely rapid inactivation. The mechanism of slow activation is not well understood and is investigated here using fluorescence as a direct measure of S4 movement and pore opening. METHODS AND FINDINGS: Tetramethylrhodamine-5-maleimide (TMRM fluorescence at E519 has been used to track S4 voltage sensor movement, and channel opening and closing in hERG channels. Endogenous cysteines (C445 and C449 in the S1-S2 linker bound TMRM, which caused a 10 mV hyperpolarization of the V((1/2 of activation to -27.5+/-2.0 mV, and showed voltage-dependent fluorescence signals. Substitution of S1-S2 linker cysteines with valines allowed unobstructed recording of S3-S4 linker E519C and L520C emission signals. Depolarization of E519C channels caused rapid initial fluorescence quenching, fit with a double Boltzmann relationship, F-V(ON, with V((1/2 (,1 = -37.8+/-1.7 mV, and V((1/2 (,2 = 43.5+/-7.9 mV. The first phase, V((1/2 (,1, was approximately 20 mV negative to the conductance-voltage relationship measured from ionic tail currents (G-V((1/2 = -18.3+/-1.2 mV, and relatively unchanged in a non-inactivating E519C:S620T mutant (V((1/2 = -34.4+/-1.5 mV, suggesting the fast initial fluorescence quenching tracked S4 voltage sensor movement. The second phase of rapid quenching was absent in the S620T mutant. The E519C fluorescence upon repolarization (V((1/2 = -20.6+/-1.2, k = 11.4 mV and L520C quenching during depolarization (V((1/2 = -26.8+/-1.0, k = 13.3 mV matched the respective voltage dependencies of hERG ionic tails, and deactivation time constants from -40 to -110 mV, suggesting they detected pore-S4 rearrangements related to ionic current flow during pore opening and closing. CONCLUSION: THE DATA INDICATE: 1

  18. State-dependent electrostatic interactions of S4 arginines with E1 in S2 during Kv7.1 activation.

    Science.gov (United States)

    Wu, Dick; Delaloye, Kelli; Zaydman, Mark A; Nekouzadeh, Ali; Rudy, Yoram; Cui, Jianmin

    2010-06-01

    The voltage-sensing domain of voltage-gated channels is comprised of four transmembrane helices (S1-S4), with conserved positively charged residues in S4 moving across the membrane in response to changes in transmembrane voltage. Although it has been shown that positive charges in S4 interact with negative countercharges in S2 and S3 to facilitate protein maturation, how these electrostatic interactions participate in channel gating remains unclear. We studied a mutation in Kv7.1 (also known as KCNQ1 or KvLQT1) channels associated with long QT syndrome (E1K in S2) and found that reversal of the charge at E1 eliminates macroscopic current without inhibiting protein trafficking to the membrane. Pairing E1R with individual charge reversal mutations of arginines in S4 (R1-R4) can restore current, demonstrating that R1-R4 interact with E1. After mutating E1 to cysteine, we probed E1C with charged methanethiosulfonate (MTS) reagents. MTS reagents could not modify E1C in the absence of KCNE1. With KCNE1, (2-sulfonatoethyl) MTS (MTSES)(-) could modify E1C, but [2-(trimethylammonium)ethyl] MTS (MTSET)(+) could not, confirming the presence of a positively charged environment around E1C that allows approach by MTSES(-) but repels MTSET(+). We could change the local electrostatic environment of E1C by making charge reversal and/or neutralization mutations of R1 and R4, such that MTSET(+) modified these constructs depending on activation states of the voltage sensor. Our results confirm the interaction between E1 and the fourth arginine in S4 (R4) predicted from open-state crystal structures of Kv channels and reveal an E1-R1 interaction in the resting state. Thus, E1 engages in electrostatic interactions with arginines in S4 sequentially during the gating movement of S4. These electrostatic interactions contribute energetically to voltage-dependent gating and are important in setting the limits for S4 movement.

  19. An intersubunit interaction between S4-S5 linker and S6 is responsible for the slow off-gating component in Shaker K+ channels.

    Science.gov (United States)

    Batulan, Zarah; Haddad, Georges A; Blunck, Rikard

    2010-04-30

    Voltage-gated ion channels are controlled by the membrane potential, which is sensed by peripheral, positively charged voltage sensors. The movement of the charged residues in the voltage sensor may be detected as gating currents. In Shaker K(+) channels, the gating currents are asymmetric; although the on-gating currents are fast, the off-gating currents contain a slow component. This slow component is caused by a stabilization of the activated state of the voltage sensor and has been suggested to be linked to ion permeation or C-type inactivation. The molecular determinants responsible for the stabilization, however, remain unknown. Here, we identified an interaction between Arg-394, Glu-395, and Leu-398 on the C termini of the S4-S5 linker and Tyr-485 on the S6 of the neighboring subunit, which is responsible for the development of the slow off-gating component. Mutation of residues involved in this intersubunit interaction modulated the strength of the associated interaction. Impairment of the interaction still led to pore opening but did not exhibit slow gating kinetics. Development of this interaction occurs under physiological ion conduction and is correlated with pore opening. We, thus, suggest that the above residues stabilize the channel in the open state.

  20. Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, H. [PBI-Dansensor A/S (Denmark); Toft Soerensen, O. [Risoe National Lab., Materials Research Dept. (Denmark)

    1999-10-01

    A new type of ceramic oxygen sensors based on semiconducting oxides was developed in this project. The advantage of these sensors compared to standard ZrO{sub 2} sensors is that they do not require a reference gas and that they can be produced in small sizes. The sensor design and the techniques developed for production of these sensors are judged suitable by the participating industry for a niche production of a new generation of oxygen sensors. Materials research on new oxygen ion conducting conductors both for applications in oxygen sensors and in fuel was also performed in this project and finally a new process was developed for fabrication of ceramic tubes by dip-coating. (EHS)

  1. Sensors

    CERN Document Server

    Pigorsch, Enrico

    1997-01-01

    This is the 5th edition of the Metra Martech Directory "EUROPEAN CENTRES OF EXPERTISE - SENSORS." The entries represent a survey of European sensors development. The new edition contains 425 detailed profiles of companies and research institutions in 22 countries. This is reflected in the diversity of sensors development programmes described, from sensors for physical parameters to biosensors and intelligent sensor systems. We do not claim that all European organisations developing sensors are included, but this is a good cross section from an invited list of participants. If you see gaps or omissions, or would like your organisation to be included, please send details. The data base invites the formation of effective joint ventures by identifying and providing access to specific areas in which organisations offer collaboration. This issue is recognised to be of great importance and most entrants include details of collaboration offered and sought. We hope the directory on Sensors will help you to find the ri...

  2. Mapping the Interaction Site for a β-Scorpion Toxin in the Pore Module of Domain III of Voltage-gated Na+ Channels*

    Science.gov (United States)

    Zhang, Joel Z.; Yarov-Yarovoy, Vladimir; Scheuer, Todd; Karbat, Izhar; Cohen, Lior; Gordon, Dalia; Gurevitz, Michael; Catterall, William A.

    2012-01-01

    Activation of voltage-gated sodium (Nav) channels initiates and propagates action potentials in electrically excitable cells. β-Scorpion toxins, including toxin IV from Centruroides suffusus suffusus (CssIV), enhance activation of NaV channels. CssIV stabilizes the voltage sensor in domain II in its activated state via a voltage-sensor trapping mechanism. Amino acid residues required for the action of CssIV have been identified in the S1-S2 and S3-S4 extracellular loops of domain II. The extracellular loops of domain III are also involved in toxin action, but individual amino acid residues have not been identified. We used site-directed mutagenesis and voltage clamp recording to investigate amino acid residues of domain III that are involved in CssIV action. In the IIISS2-S6 loop, five substitutions at four positions altered voltage-sensor trapping by CssIVE15A. Three substitutions (E1438A, D1445A, and D1445Y) markedly decreased voltage-sensor trapping, whereas the other two substitutions (N1436G and L1439A) increased voltage-sensor trapping. These bidirectional effects suggest that residues in IIISS2-S6 make both positive and negative interactions with CssIV. N1436G enhanced voltage-sensor trapping via increased binding affinity to the resting state, whereas L1439A increased voltage-sensor trapping efficacy. Based on these results, a three-dimensional model of the toxin-channel interaction was developed using the Rosetta modeling method. These data provide additional molecular insight into the voltage-sensor trapping mechanism of toxin action and define a three-point interaction site for β-scorpion toxins on NaV channels. Binding of α- and β-scorpion toxins to two distinct, pseudo-symmetrically organized receptor sites on NaV channels acts synergistically to modify channel gating and paralyze prey. PMID:22761417

  3. Mapping the interaction site for a β-scorpion toxin in the pore module of domain III of voltage-gated Na(+) channels.

    Science.gov (United States)

    Zhang, Joel Z; Yarov-Yarovoy, Vladimir; Scheuer, Todd; Karbat, Izhar; Cohen, Lior; Gordon, Dalia; Gurevitz, Michael; Catterall, William A

    2012-08-31

    Activation of voltage-gated sodium (Na(v)) channels initiates and propagates action potentials in electrically excitable cells. β-Scorpion toxins, including toxin IV from Centruroides suffusus suffusus (CssIV), enhance activation of Na(V) channels. CssIV stabilizes the voltage sensor in domain II in its activated state via a voltage-sensor trapping mechanism. Amino acid residues required for the action of CssIV have been identified in the S1-S2 and S3-S4 extracellular loops of domain II. The extracellular loops of domain III are also involved in toxin action, but individual amino acid residues have not been identified. We used site-directed mutagenesis and voltage clamp recording to investigate amino acid residues of domain III that are involved in CssIV action. In the IIISS2-S6 loop, five substitutions at four positions altered voltage-sensor trapping by CssIV(E15A). Three substitutions (E1438A, D1445A, and D1445Y) markedly decreased voltage-sensor trapping, whereas the other two substitutions (N1436G and L1439A) increased voltage-sensor trapping. These bidirectional effects suggest that residues in IIISS2-S6 make both positive and negative interactions with CssIV. N1436G enhanced voltage-sensor trapping via increased binding affinity to the resting state, whereas L1439A increased voltage-sensor trapping efficacy. Based on these results, a three-dimensional model of the toxin-channel interaction was developed using the Rosetta modeling method. These data provide additional molecular insight into the voltage-sensor trapping mechanism of toxin action and define a three-point interaction site for β-scorpion toxins on Na(V) channels. Binding of α- and β-scorpion toxins to two distinct, pseudo-symmetrically organized receptor sites on Na(V) channels acts synergistically to modify channel gating and paralyze prey.

  4. X-ray crystal structure of voltage-gated proton channel.

    Science.gov (United States)

    Takeshita, Kohei; Sakata, Souhei; Yamashita, Eiki; Fujiwara, Yuichiro; Kawanabe, Akira; Kurokawa, Tatsuki; Okochi, Yoshifumi; Matsuda, Makoto; Narita, Hirotaka; Okamura, Yasushi; Nakagawa, Atsushi

    2014-04-01

    The voltage-gated proton channel Hv1 (or VSOP) has a voltage-sensor domain (VSD) with dual roles of voltage sensing and proton permeation. Its gating is sensitive to pH and Zn(2+). Here we present a crystal structure of mouse Hv1 in the resting state at 3.45-Å resolution. The structure showed a 'closed umbrella' shape with a long helix consisting of the cytoplasmic coiled coil and the voltage-sensing helix, S4, and featured a wide inner-accessible vestibule. Two out of three arginines in S4 were located below the phenylalanine constituting the gating charge-transfer center. The extracellular region of each protomer coordinated a Zn(2+), thus suggesting that Zn(2+) stabilizes the resting state of Hv1 by competing for acidic residues that otherwise form salt bridges with voltage-sensing positive charges on S4. These findings provide a platform for understanding the general principles of voltage sensing and proton permeation.

  5. Two mutations in the IV/S4-S5 segment of the human skeletal muscle Na+ channel disrupt fast and enhance slow inactivation.

    Science.gov (United States)

    Alekov, A K; Peter, W; Mitrovic, N; Lehmann-Horn, F; Lerche, H

    2001-06-29

    Fast and slow inactivation (FI, SI) of the voltage-gated Na+ channel are two kinetically distinct and structurally dissociated processes. The voltage sensor IV/S4 and the intracellular IV/S4-S5 loop have been shown to play an important role in FI mediating the coupling between activation and inactivation. Two mutations in IV/S4-S5 of the human muscle Na+ channel, L1482C/A, disrupt FI by inducing a persistent Na+ current, shifting steady-state inactivation in the depolarizing direction and accelerating its recovery. These effects were more pronounced for L1482A. In contrast, SI of L1482C/A channels was enhanced showing a more complete SI and a 3-fold slowing of its recovery. Effects on SI were more pronounced for L1482C. The results indicate an important role of the IV/S4-S5 loop not only in FI but also in SI of the Na+ channel.

  6. Interactions between S4-S5 linker and S6 transmembrane domain modulate gating of HERG K+ channels.

    Science.gov (United States)

    Tristani-Firouzi, Martin; Chen, Jun; Sanguinetti, Michael C

    2002-05-24

    Outward movement of the voltage sensor is coupled to activation in voltage-gated ion channels; however, the precise mechanism and structural basis of this gating event are poorly understood. Potential insight into the coupling mechanism was provided by our previous finding that mutation to Lys of a single residue (Asp(540)) located in the S4-S5 linker endowed HERG (human ether-a-go-go-related gene) K(+) channels with the unusual ability to open in response to membrane depolarization and hyperpolarization in a voltage-dependent manner. We hypothesized that the unusual hyperpolarization-induced gating occurred through an interaction between Lys(540) and the C-terminal end of the S6 domain, the region proposed to form the activation gate. Therefore, we mutated six residues located in this region of S6 (Ile(662)-Tyr(667)) to Ala in D540K HERG channels. Mutation of Arg(665), but not the other five residues, prevented hyperpolarization-dependent reopening of D540K HERG channels. Mutation of Arg(665) to Gln or Asp also prevented reopening. In addition, D540R and D540K/R665K HERG reopened in response to hyperpolarization. Together these findings suggest that a single residue (Arg(665)) in the S6 domain interacts with Lys(540) by electrostatic repulsion to couple voltage sensing to hyperpolarization-dependent opening of D540K HERG K(+) channels. Moreover, our findings suggest that the C-terminal ends of S4 and S6 are in close proximity at hyperpolarized membrane potentials.

  7. Orientations and proximities of the extracellular ends of transmembrane helices S0 and S4 in open and closed BK potassium channels.

    Directory of Open Access Journals (Sweden)

    Xiaowei Niu

    Full Text Available The large-conductance potassium channel (BK α subunit contains a transmembrane (TM helix S0 preceding the canonical TM helices S1 through S6. S0 lies between S4 and the TM2 helix of the regulatory β1 subunit. Pairs of Cys were substituted in the first helical turns in the membrane of BK α S0 and S4 and in β1 TM2. One such pair, W22C in S0 and W203C in S4, was 95% crosslinked endogenously. Under voltage-clamp conditions in outside-out patches, this crosslink was reduced by DTT and reoxidized by a membrane-impermeant bis-quaternary ammonium derivative of diamide. The rate constants for this reoxidation were not significantly different in the open and closed states of the channel. Thus, these two residues are approximately equally close in the two states. In addition, 90% crosslinking of a second pair, R20C in S0 and W203C in S4, had no effect on the V50 for opening. Taken together, these findings indicate that separation between residues at the extracellular ends of S0 and S4 is not required for voltage-sensor activation. On the contrary, even though W22C and W203C were equally likely to form a disulfide in the activated and deactivated states, relative immobilization by crosslinking of these two residues favored the activated state. Furthermore, the efficiency of recrosslinking of W22C and W203C on the cell surface was greater in the presence of the β1 subunit than in its absence, consistent with β1 acting through S0 to stabilize its immobilization relative to α S4.

  8. Three-dimensional structure of the S4-S5 segment of the Shaker potassium channel.

    Science.gov (United States)

    Ohlenschläger, Oliver; Hojo, Hironobu; Ramachandran, Ramadurai; Görlach, Matthias; Haris, Parvez I

    2002-06-01

    The propagation of action potentials during neuronal signal transduction in phospholipid membranes is mediated by ion channels, a diverse group of membrane proteins. The S4-S5 linker peptide (S4-S5), that connects the S4 and S5 transmembrane segments of voltage-gated potassium channels is an important region of the Shaker ion-channel protein. Despite its importance, very little is known about its structure. Here we provide evidence for an amphipathic alpha-helical conformation of a synthetic S4-S5 peptide of the voltage-gated Drosophila melanogaster Shaker potassium channel in water/trifluoroethanol and in aqueous phospholipid micelles. The three-dimensional solution structures of the S4-S5 peptide were obtained by high-resolution nuclear magnetic resonance spectroscopy and distance-geometry/simulated-annealing calculations. The detailed structural features are discussed with respect to model studies and available mutagenesis data on the mechanism and selectivity of the potassium channel.

  9. Scalar Field Theory on Fuzzy S^4

    CERN Document Server

    Medina, J; Medina, Julieta; Connor, Denjoe O'

    2003-01-01

    Scalar fields are studied on fuzzy $S^4$ and a solution is found for the elimination of the unwanted degrees of freedom that occur in the model. The resulting theory can be interpreted as a Kaluza-Klein reduction of CP^3 to S^4 in the fuzzy context.

  10. 激励电压对汽车碰撞试验传感器输出的影响分析%Analysis on Effect of Excitation Voltage on Sensor Output during the Automotive Crash Test

    Institute of Scientific and Technical Information of China (English)

    郑佳丽; 张毅; 韩刚; 刘卫国; 赵福全

    2013-01-01

      碰撞试验中,假人及传感器组成数据采集系统的第一部分,输出的数据反映了冲击环境中模拟人体的生物力学响应。因此,最终的数据结果非常重要。传感器激励电压的不同,产生的热量也不同。碰撞试验中使用的传感器数量达200多个,因此假人体内会因激励电压产生较大的热量,从而产生温度误差,最终引起数据的不准确。因此,在碰撞试验中,要确保假人体内温度与标准符合;要求传感器标定电压与数据采集输入的激励电压一致。%The dummy and sensors constitute the first part of a data acquisition system during the crash test. The output data reflects the biomechanical response of a simulation human body under impact environment; therefore, final data results are quite important. The different excitation voltages of sensors usually generate different heat amount. There are more than 200 sensors which are used in the crash test. Hence, more heat amount may be produced in a dummy body due to excitation voltage, thus leading to temperature error. The incorrect data would be ultimately created. Therefore, it is guaranteed that body temperature of dummy conforms to standard during the crash test. Furthermore, it is also required that calibration voltage of sensors is always consistent with excitation voltage intended for data acquisition.

  11. Cu2ZnSiS4

    Directory of Open Access Journals (Sweden)

    Kimberly A. Rosmus

    2011-04-01

    Full Text Available Single crystals of Cu2ZnSiS4, dicopper(I zinc silicon tetrasulfide, have been prepared via high-temperature solid-state synthesis. Cu2ZnSiS4 was found to have the wurtz-stannite structure type, like that of Li2CdGeS4, Li2CdSnS4, and Cu2CdSiS4. Each sulfur anion is tetrahedrally coordinated by two Cu cations, one Si cation, and one Zn cation, forming a three-dimensional honeycomb structure. When viewed along the c axis, the atoms are aligned in rows in which each cation alternates with the sulfur anions.

  12. Giant magnetoimpedance intrinsic impedance and voltage sensitivity of rapidly solidified Co66Fe2Cr4Si13B15 amorphous wire for highly sensitive sensors applications

    Science.gov (United States)

    Das, Tarun K.; Banerji, Pallab; Mandal, Sushil K.

    2016-11-01

    We report a systematic study of the influence of wire length, L, dependence of giant magneto-impedance (GMI) sensitivity of Co66Fe2Cr4Si13B15 soft magnetic amorphous wire of diameter ~100 µm developed by in-water quenching technique. The magnetization behaviour (hysteresis loops) of the wire with different length ( L = 1, 2, 3, 5, 8 and 10 cm) has been evaluated by fuxmetric induction method. It was observed that the behaviour of the hysteresis loops change drastically with the wire length, being attributed to the existence of a critical length, L C, found to be around 3 cm. GMI measurements have been taken using automated GMI measurement system and the GMI sensitivities in terms of intrinsic impedance sensitivity ( S Ω/Am -1) and voltage sensitivity ( S V/Am -1) of the wire have been evaluated under optimal bias field and excitation current. It was found that the maximum ( S Ω/Am -1) max ≈ 0.63 Ω/kAm-1/cm and ( S V/Am -1) max ≈ 3.10 V/kAm-1/cm were achieved at a critical length L C ~ 3 cm of the wire for an AC current of 5 mA and a frequency of 5 MHz. These findings provide crucial insights for optimization of the geometrical dimensions of magnetic sensing elements and important practical guidance for designing high sensitive GMI sensors. The relevant combinations of magnetic material parameters and operating conditions that optimize the sensitivity are highlighted.

  13. Isomerically Pure Tetramethylrhodamine Voltage Reporters.

    Science.gov (United States)

    Deal, Parker E; Kulkarni, Rishikesh U; Al-Abdullatif, Sarah H; Miller, Evan W

    2016-07-27

    We present the design, synthesis, and application of a new family of fluorescent voltage indicators based on isomerically pure tetramethylrhodamines. These new Rhodamine Voltage Reporters, or RhoVRs, use photoinduced electron transfer (PeT) as a trigger for voltage sensing, display excitation and emission profiles in the green to orange region of the visible spectrum, demonstrate high sensitivity to membrane potential changes (up to 47% ΔF/F per 100 mV), and employ a tertiary amide derived from sarcosine, which aids in membrane localization and simultaneously simplifies the synthetic route to the voltage sensors. The most sensitive of the RhoVR dyes, RhoVR 1, features a methoxy-substituted diethylaniline donor and phenylenevinylene molecular wire at the 5'-position of the rhodamine aryl ring, exhibits the highest voltage sensitivity to date for red-shifted PeT-based voltage sensors, and is compatible with simultaneous imaging alongside green fluorescent protein-based indicators. The discoveries that sarcosine-based tertiary amides in the context of molecular-wire voltage indicators prevent dye internalization and 5'-substituted voltage indicators exhibit improved voltage sensitivity should be broadly applicable to other types of PeT-based voltage-sensitive fluorophores.

  14. Hydrophobic plug functions as a gate in voltage-gated proton channels.

    Science.gov (United States)

    Chamberlin, Adam; Qiu, Feng; Rebolledo, Santiago; Wang, Yibo; Noskov, Sergei Y; Larsson, H Peter

    2014-01-14

    Voltage-gated proton (Hv1) channels play important roles in the respiratory burst, in pH regulation, in spermatozoa, in apoptosis, and in cancer metastasis. Unlike other voltage-gated cation channels, the Hv1 channel lacks a centrally located pore formed by the assembly of subunits. Instead, the proton permeation pathway in the Hv1 channel is within the voltage-sensing domain of each subunit. The gating mechanism of this pathway is still unclear. Mutagenic and fluorescence studies suggest that the fourth transmembrane (TM) segment (S4) functions as a voltage sensor and that there is an outward movement of S4 during channel activation. Using thermodynamic mutant cycle analysis, we find that the conserved positively charged residues in S4 are stabilized by countercharges in the other TM segments both in the closed and open states. We constructed models of both the closed and open states of Hv1 channels that are consistent with the mutant cycle analysis. These structural models suggest that electrostatic interactions between TM segments in the closed state pull hydrophobic residues together to form a hydrophobic plug in the center of the voltage-sensing domain. Outward S4 movement during channel activation induces conformational changes that remove this hydrophobic plug and instead insert protonatable residues in the center of the channel that, together with water molecules, can form a hydrogen bond chain across the channel for proton permeation. This suggests that salt bridge networks and the hydrophobic plug function as the gate in Hv1 channels and that outward movement of S4 leads to the opening of this gate.

  15. Membrane Potential-dependent Uptake of 18F-triphenylphosphonium - A New Voltage Sensor as an Imaging Agent for Detecting Burn-induced Apoptosis

    Science.gov (United States)

    Zhao, Gaofeng; Yu, Yong-Ming; Shoup, Timothy M.; Elmaleh, David R.; Bonab, Ali A.; Tompkins, Ronald G.; Fischman, Alan J.

    2014-01-01

    Background Mitochondrial dysfunction has been closely related to many pathological processes, such as cellular apoptosis. Alterations in organelle membrane potential are associated with mitochondrial dysfunction. A fluorine -18 labeled phosphonium compound: 18F-triphenylphosphonium (18F-TPP) was prepared to determine its potential use as a mitochondria-targeting radiopharmaceutical to evaluate cellular apoptosis. Methods Studies were conducted in both ex vivo cell lines and in vivo using a burned animal model. Uptake of 18F-TPP was assessed in PC-3 cells by gamma counting under the following conditions: graded levels of extra-cellular potassium concentrations, incubation with carbonyl cyanide m-chlorophenylhydrazone (CCCP) and staurosporine. Apoptosis was studied in a burn animal model using TUNEL staining and simultaneous assessment of 18F-TPP uptake by biodistribution. Results We found that stepwise membrane depolarization by potassium (K) resulted in a linear decrease in 18F-TPP uptake, with a slope of 0.62+/−0.08 and a correlation coefficient of 0.936+/−0.11. Gradually increased concentrations of CCCP lead to decreased uptakes of 18F-TPP. Staurosporine significantly decreased the uptake of 18F-TPP in PC-3 cells from 14.2+/−3.8% to 5.6+/−1.3% (P<0.001). Burn induced significant apoptosis (sham: 4.4 +/−1.8% vs. burn: 24.6+/− 6.7 %; p<0.005) and a reduced uptake of tracer in the spleens of burn injured animals as compared to sham burn controls (burn: 1.13+/−0.24% vs. sham: 3.28+/−0.67%; p<0.005). Biodistribution studies demonstrated that burn induced significant reduction in 18F-TPP uptake in spleen, heart, lung, and liver, which were associated with significantly increased apoptosis. Conclusions 18F-TPP is a promising new voltage sensor for detecting mitochondrial dysfunction and apoptosis in various tissues. PMID:24582214

  16. The α2δ-1 subunit remodels CaV1.2 voltage sensors and allows Ca2+ influx at physiological membrane potentials

    Science.gov (United States)

    Pantazis, Antonios; Sigg, Daniel; Weiss, James N.; Neely, Alan

    2016-01-01

    Excitation-evoked calcium influx across cellular membranes is strictly controlled by voltage-gated calcium channels (CaV), which possess four distinct voltage-sensing domains (VSDs) that direct the opening of a central pore. The energetic interactions between the VSDs and the pore are critical for tuning the channel’s voltage dependence. The accessory α2δ-1 subunit is known to facilitate CaV1.2 voltage-dependent activation, but the underlying mechanism is unknown. In this study, using voltage clamp fluorometry, we track the activation of the four individual VSDs in a human L-type CaV1.2 channel consisting of α1C and β3 subunits. We find that, without α2δ-1, the channel complex displays a right-shifted voltage dependence such that currents mainly develop at nonphysiological membrane potentials because of very weak VSD–pore interactions. The presence of α2δ-1 facilitates channel activation by increasing the voltage sensitivity (i.e., the effective charge) of VSDs I–III. Moreover, the α2δ-1 subunit also makes VSDs I–III more efficient at opening the channel by increasing the coupling energy between VSDs II and III and the pore, thus allowing Ca influx within the range of physiological membrane potentials. PMID:27481713

  17. Samsung Galaxy S4 for dummies

    CERN Document Server

    Hughes, Bill

    2013-01-01

    Explore a world of possibilities with your Samsung Galaxy S 4 smartphone Everything's more exciting when you've got the Galaxy in your hand. Let For Dummies be your guide to getting the most out of your Galaxy S 4. You'll cruise through the smartphone basics and set up process before moving on to the fun stuff like staying in touch with e-mail and texting, surfing the web, navigating with maps, shooting and sharing photos and video, watching movies, listening to music, and so much more. Whether you're entering the smartphone world for the first time or just moving up to

  18. Low-noise Magnetic Sensors

    KAUST Repository

    Kosel, Jurgen

    2014-03-27

    Magnetic sensors are disclosed, as well as methods for fabricating and using the same. In some embodiments, an EMR effect sensor includes a semiconductor layer. In some embodiments, the EMR effect sensor may include a conductive layer substantially coupled to the semiconductor layer. In some embodiments, the EMR effect sensor may include a voltage lead coupled to the conductive layer. In some embodiments, the voltage lead may be configured to provide a voltage for measurement by a voltage measurement circuit. In some embodiments, the EMR effect sensor may include a second voltage lead coupled to the semiconductor layer. In some embodiments, the second voltage lead may be configured to provide a voltage for measurement by a voltage measurement circuit. Embodiments of a Hall effect sensor having the same or similar structure are also disclosed.

  19. 差动变压器式位移传感器零位电压研究%Study on Zero-point Remainder Voltage of Differential Transformer Displacement Sensor

    Institute of Scientific and Technical Information of China (English)

    贾惠霞; 王健; 张娟

    2015-01-01

    The principle of the differential transformer displacement sensor is very simple,and it is very easy to realize.The measurement errors exit not only because of zero-point remainder voltage of the carrier,but also because of the circuit drift in the process of signal processing.This article was based on the principle and the signal processing of this kind of sensor,and the princi-ple of zero-point remainder voltage and the method of removing it were introduced,thus improving the certainty of measurement.The main part of null voltage was proved through MATLAB simulation and experiment,thus proving the importance of magnetic circuit symmetry in the differential transformer displacement sensor.%差动变压器式位移传感器原理简单,便于实现。但是位移传感器会产生零位电压,同时在信号处理过程中,电路漂移也会引起测量误差。文中主要基于这种传感器的工作原理和信号处理过程,阐述零位电压产生的机理和消除的方法,提高传感器的测量精度,并用MATLAB仿真和实验的方法证明零位电压产生的主要部位,进而说明差动变压器式位移传感器加工时保证磁路对称的重要性。

  20. Three-dimensional structure of the S4-S5 segment of the Shaker potassium channel.

    OpenAIRE

    2002-01-01

    The propagation of action potentials during neuronal signal transduction in phospholipid membranes is mediated by ion channels, a diverse group of membrane proteins. The S4-S5 linker peptide (S4-S5), that connects the S4 and S5 transmembrane segments of voltage-gated potassium channels is an important region of the Shaker ion-channel protein. Despite its importance, very little is known about its structure. Here we provide evidence for an amphipathic alpha-helical conformation of a synthetic ...

  1. Functional interactions between residues in the S1, S4, and S5 domains of Kv2.1.

    Science.gov (United States)

    Bocksteins, E; Ottschytsch, N; Timmermans, J-P; Labro, A J; Snyders, D J

    2011-06-01

    The voltage-gated potassium channel subunit Kv2.1 forms heterotetrameric channels with the silent subunit Kv6.4. Chimeric Kv2.1 channels containing a single transmembrane segment from Kv6.4 have been shown to be functional. However, a Kv2.1 chimera containing both S1 and S5 from Kv6.4 was not functional. Back mutation of individual residues in this chimera (to the Kv2.1 counterpart) identified four positions that were critical for functionality: A200V and A203T in S1, and T343M and P347S in S5. To test for possible interactions in Kv2.1, we used substitutions with charged residues and tryptophan for the outermost pair 203/347. Combinations of substitutions with opposite charges at both T203 and S347 were tolerated but resulted in channels with altered gating kinetics, as did the combination of negatively charged aspartate substitutions. Double mutant cycle analysis with these mutants indicated that both residues are energetically coupled. In contrast, replacing both residues with a positively charged lysine together (T203K + S347K) was not tolerated and resulted in a folding or trafficking deficiency. The nonfunctionality of the T203K + S347K mutation could be restored by introducing the R300E mutation in the S4 segment of the voltage sensor. These results indicate that these specific S1, S4, and S5 residues are in close proximity and interact with each other in the functional channel, but are also important determinants for Kv2.1 channel maturation. These data support the view of an anchoring interaction between S1 and S5, but indicate that this interaction surface is more extensive than previously proposed.

  2. Mapping of sites facing aqueous environment of voltage-gated proton channel at resting state: a study with PEGylation protection.

    Science.gov (United States)

    Kurokawa, Tatsuki; Okamura, Yasushi

    2014-01-01

    Hv1 (also named, voltage-sensor only protein, VSOP) lacks an authentic pore domain, and its voltage sensor domain plays both roles in voltage sensing and proton permeation. The activities of a proton channel are intrinsic to protomers of Hv1, while Hv1 is dimeric in biological membranes; cooperative gating is exerted by interaction between two protomers. As the signature pattern conserved among voltage-gated channels and voltage-sensing phosphatase, Hv1 has multiple arginines intervened by two hydrophobic residues on the fourth transmembrane segment, S4. S4 moves upward relative to other helices upon depolarization, causing conformational change possibly leading to the formation of a proton-selective conduction pathway. However, detailed mechanisms of proton-selectivity and gating of Hv1 are unknown. Here we took an approach of PEGylation protection assay to define residues facing the aqueous environment of mouse Hv1 (mHv1). Accessibilities of two maleimide molecules, N-ethylmaleimide (NEM) and 4-acetamido-4'-maleimidylstilbene-2,2'-disulfonic acid (AMS), were examined on cysteine introduced into individual sites. Only the first arginine on S4 (R1: R201) was inaccessible by NEM and AMS in mHv1. This is consistent with previous results of electrophysiology on the resting state channel, suggesting that the accessibility profile represents the resting state of mHv1. D108, critical for proton selectivity, was accessible by AMS and NEM, suggesting that D108 faces the vestibule. F146, a site critical for blocking by a guanidinium-reagent, was accessible by NEM, suggesting that F146 also faces the inner vestibule. These findings suggest an inner vestibule lined by several residues on S2 including F146, D108 on S1, and the C-terminal half of S4. © 2013.

  3. Molecular mechanisms underlying the effect of the novel BK channel opener GoSlo: involvement of the S4/S5 linker and the S6 segment.

    Science.gov (United States)

    Webb, Timothy I; Kshatri, Aravind Singh; Large, Roddy J; Akande, Adebola Morayo; Roy, Subhrangsu; Sergeant, Gerard P; McHale, Noel G; Thornbury, Keith D; Hollywood, Mark A

    2015-02-17

    GoSlo-SR-5-6 is a novel large-conductance Ca(2+)-activated K(+) (BK) channel agonist that shifts the activation V1/2 of these channels in excess of -100 mV when applied at a concentration of 10 μM. Although the structure-activity relationship of this family of molecules has been established, little is known about how they open BK channels. To help address this, we used a combination of electrophysiology, mutagenesis, and mathematical modeling to investigate the molecular mechanisms underlying the effect of GoSlo-SR-5-6. Our data demonstrate that the effects of this agonist are practically abolished when three point mutations are made: L227A in the S4/S5 linker in combination with S317R and I326A in the S6C region. Our data suggest that GoSlo-SR-5-6 interacts with the transmembrane domain of the channel to enhance pore opening. The Horrigan-Aldrich model suggests that GoSlo-SR-5-6 works by stabilizing the open conformation of the channel and the activated state of the voltage sensors, yet decouples the voltage sensors from the pore gate.

  4. The Molecular Basis of Polyunsaturated Fatty Acid Interactions with the Shaker Voltage-Gated Potassium Channel.

    Directory of Open Access Journals (Sweden)

    Samira Yazdi

    2016-01-01

    Full Text Available Voltage-gated potassium (KV channels are membrane proteins that respond to changes in membrane potential by enabling K+ ion flux across the membrane. Polyunsaturated fatty acids (PUFAs induce channel opening by modulating the voltage-sensitivity, which can provide effective treatment against refractory epilepsy by means of a ketogenic diet. While PUFAs have been reported to influence the gating mechanism by electrostatic interactions to the voltage-sensor domain (VSD, the exact PUFA-protein interactions are still elusive. In this study, we report on the interactions between the Shaker KV channel in open and closed states and a PUFA-enriched lipid bilayer using microsecond molecular dynamics simulations. We determined a putative PUFA binding site in the open state of the channel located at the protein-lipid interface in the vicinity of the extracellular halves of the S3 and S4 helices of the VSD. In particular, the lipophilic PUFA tail covered a wide range of non-specific hydrophobic interactions in the hydrophobic central core of the protein-lipid interface, while the carboxylic head group displayed more specific interactions to polar/charged residues at the extracellular regions of the S3 and S4 helices, encompassing the S3-S4 linker. Moreover, by studying the interactions between saturated fatty acids (SFA and the Shaker KV channel, our study confirmed an increased conformational flexibility in the polyunsaturated carbon tails compared to saturated carbon chains, which may explain the specificity of PUFA action on channel proteins.

  5. Kv channel gating requires a compatible S4-S5 linker and bottom part of S6, constrained by non-interacting residues.

    Science.gov (United States)

    Labro, Alain J; Raes, Adam L; Grottesi, Alessandro; Van Hoorick, Diane; Sansom, Mark S P; Snyders, Dirk J

    2008-12-01

    Voltage-dependent K(+) channels transfer the voltage sensor movement into gate opening or closure through an electromechanical coupling. To test functionally whether an interaction between the S4-S5 linker (L45) and the cytoplasmic end of S6 (S6(T)) constitutes this coupling, the L45 in hKv1.5 was replaced by corresponding hKv2.1 sequence. This exchange was not tolerated but could be rescued by also swapping S6(T). Exchanging both L45 and S6(T) transferred hKv2.1 kinetics to an hKv1.5 background while preserving the voltage dependence. A one-by-one residue substitution scan of L45 and S6(T) in hKv1.5 further shows that S6(T) needs to be alpha-helical and forms a "crevice" in which residues I422 and T426 of L45 reside. These residues transfer the mechanical energy onto the S6(T) crevice, whereas other residues in S6(T) and L45 that are not involved in the interaction maintain the correct structure of the coupling.

  6. Detection Method of High Voltage Circuit Breaker and Its Application Based on Ultrasonic Sensor%基于超声波传感器的高压断路器检测方法及应用

    Institute of Scientific and Technical Information of China (English)

    程旭东; 王兰芳

    2011-01-01

    In order to improve the efficiency and precision of velocity detection of High voltage circuit breaker (HVCB), a detection method based on ultrasonic sensor is proposed. The TR40 series of ultrasonic transducer is adopted to generate ultrasonic signals. The emission sensor is fixed on the breaker's closing/opening connection rod while receiving sensor installed in the universal triangular bracket. By measuring the frequency difference between emission signals and receiving signals, instantaneous velocity of the current circuit breaker operation can be calculated. Furthermore, a mechanical characteristic detection instrument for HVCB is developed. Field test results show that the ultrasonic sensor is convenient to be installed and the results has high accuracy and small uncertainty, which satisfies the field test requirements for velocity detection of HVCB.%为提高高压断路器速度检测效率与精度,提出了一种基于超声波传感器的高压断路器速度检测方法,利用TR40系列超声波换能器产生超声波信号,将发射传感器固定于断路器合/分连接杆上,接收传感器安装在万能三角支架上,通过统计接收和发送信号的频率差,计算当前断路器运行的瞬时速度,并在此基础上开发了断路器机械特性测试仪.现场试验结果表明,超声波传感器安装方便、测试数据精度较高、不确定度小,能满足高压断路器现场速度检测的需求.

  7. The S4-S5 loop contributes to the ion-selective pore of potassium channels.

    Science.gov (United States)

    Slesinger, P A; Jan, Y N; Jan, L Y

    1993-10-01

    Mutagenesis experiments on voltage-gated K+ channels have suggested that the ion-selective pore is comprised mostly of H5 segments. To see whether regions outside of the H5 segment might also contribute to the pore structure, we have studied the effect of single amino acid substitutions in the segment that connects the S4 and S5 putative transmembrane segments (S4-S5 loop) on various permeation properties of Shaker K+ channels. Mutations in the S4-S5 loop alter the Rb+ selectivity, the single-channel K+ and Rb+ conductances, and the sensitivity to open channel block produced by intracellular tetraethylammonium ion, Ba2+, and Mg2+. The block of Shaker K+ channels by intracellular Mg2+ is surprising, but is reminiscent of the internal Mg2+ blockade of inward rectifier K+ channels. The results suggest that the S4-S5 loop constitutes part of the ion-selective pore. Thus, the S4-S5 loop and the H5 segment are likely to contribute to the long pore characteristic of voltage-gated K+ channels.

  8. Role of hydrophobic and ionic forces in the movement of S4 of the Shaker potassium channel.

    Science.gov (United States)

    Elliott, David J S; Neale, Edward J; Munsey, Tim S; Bannister, John P; Sivaprasadarao, Asipu

    2012-12-01

    Voltage-gated ion (K(+), Na(+), Ca(2+)) channels contain a pore domain (PD) surrounded by four voltage sensing domains (VSD). Each VSD is made up of four transmembrane helices, S1-S4. S4 contains 6-7 positively charged residues (arginine/lysine) separated two hydrophobic residues, whereas S1-S3 contribute to two negatively charged clusters. These structures are conserved among all members of the voltage-gated ion channel family and play essential roles in voltage gating. The role of S4 charged residues in voltage gating is well established: During depolarization, they move out of the membrane electric field, exerting a mechanical force on channel gates, causing them to open. However, the role of the intervening hydrophobic residues in voltage sensing is unclear. Here we studied the role of these residues in the prototypical Shaker potassium channel. We have altered the physicochemical properties of both charged and hydrophobic positions of S4 and examined the effect of these modifications on the gating properties of the channel. For this, we have introduced cysteines at each of these positions, expressed the mutants in Xenopus oocytes, and examined the effect of in situ addition of charge, via Cd(2+), on channel gating by two-electrode voltage clamp. Our results reveal a face of the S4 helix (comprising residues L358, L361, R365 and R368) where introduction of charge at hydrophobic positions destabilises the closed state and removal of charges from charged positions has an opposite effect. We propose that hydrophobic residues play a crucial role in limiting gating to a physiological voltage range.

  9. High Voltage Switchgear Temperature Acquisition System Based on SAW Sensor Technology Analysis%基于 SAW 传感器技术的高压开关柜温度采集系统设计分析

    Institute of Scientific and Technical Information of China (English)

    郭翠玲; 高丽

    2015-01-01

    根据传统高压开关柜温度采集方法的不足,采用 SAW 传感器技术对高压开关柜进行无源无线温度采集。该系统具有温度测量、报警功能、参数设定、数据存储等功能,对温度进行远程实时在线监测,是智能电网建设的重要依据。%Based on the shortcomings of the traditional method of temperature measurement of high voltage switchgear ,the paper uses SAW sensor technology to take passive wireless temperature measurement for high voltage switchgear .T he system ,w hich has temperature measurement ,alarm function ,parameter setting ,data storage and other functions that can take real - time remote temperature online monito‐ring ,is an important basis for smart grid construction .

  10. The dipeptidyl-aminopeptidase-like protein 6 is an integral voltage sensor-interacting beta-subunit of neuronal K(V)4.2 channels.

    Science.gov (United States)

    Dougherty, Kevin; Tu, Liwei; Deutsch, Carol; Covarrubias, Manuel

    2009-01-01

    Auxiliary beta-subunits dictate the physiological properties of voltage-gated K(+) (K(V)) channels in excitable tissues. In many instances, however, the underlying mechanisms of action are poorly understood. The dipeptidyl-aminopeptidase-like protein 6 (DPP6) is a specific beta-subunit of neuronal K(V)4 channels, which may promote gating through interactions between the single transmembrane segment of DPP6 and the channel's voltage sensing domain (VSD). A combination of gating current measurements and protein biochemistry (in-vitro translation and co-immunoprecipitations) revealed preferential physical interaction between the isolated K(V)4.2-VSD and DPP6. Significantly weaker interactions were detected between DPP6 and K(V)1.3 channels or the K(V)4.2 pore domain. More efficient gating charge movement resulting from a direct interaction between DPP6 and the K(V)4.2-VSD is unique among the known actions of K(V) channel beta-subunits. This study shows that the modular VSD of a K(V) channel can be directly regulated by transmembrane protein-protein interactions involving an extrinsic beta-subunit. Understanding these interactions may shed light on the pathophysiology of recently identified human disorders associated with mutations affecting the dpp6 gene.

  11. A surface plasmon resonance approach to monitor toxin interactions with an isolated voltage-gated sodium channel paddle motif.

    Science.gov (United States)

    Martin-Eauclaire, Marie-France; Ferracci, Géraldine; Bosmans, Frank; Bougis, Pierre E

    2015-02-01

    Animal toxins that inhibit voltage-gated sodium (Na(v)) channel fast inactivation can do so through an interaction with the S3b-S4 helix-turn-helix region, or paddle motif, located in the domain IV voltage sensor. Here, we used surface plasmon resonance (SPR), an optical approach that uses polarized light to measure the refractive index near a sensor surface to which a molecule of interest is attached, to analyze interactions between the isolated domain IV paddle and Na(v) channel-selective α-scorpion toxins. Our SPR analyses showed that the domain IV paddle can be removed from the Na(v) channel and immobilized on sensor chips, and suggest that the isolated motif remains susceptible to animal toxins that target the domain IV voltage sensor. As such, our results uncover the inherent pharmacological sensitivities of the isolated domain IV paddle motif, which may be exploited to develop a label-free SPR approach for discovering ligands that target this region.

  12. Accurate Switched-Voltage voltage averaging circuit

    OpenAIRE

    金光, 一幸; 松本, 寛樹

    2006-01-01

    Abstract ###This paper proposes an accurate Switched-Voltage (SV) voltage averaging circuit. It is presented ###to compensated for NMOS missmatch error at MOS differential type voltage averaging circuit. ###The proposed circuit consists of a voltage averaging and a SV sample/hold (S/H) circuit. It can ###operate using nonoverlapping three phase clocks. Performance of this circuit is verified by PSpice ###simulations.

  13. Extracellular Linkers Completely Transplant the Voltage Dependence from Kv1.2 Ion Channels to Kv2.1.

    Science.gov (United States)

    Elinder, Fredrik; Madeja, Michael; Zeberg, Hugo; Århem, Peter

    2016-10-18

    The transmembrane voltage needed to open different voltage-gated K (Kv) channels differs by up to 50 mV from each other. In this study we test the hypothesis that the channels' voltage dependences to a large extent are set by charged amino-acid residues of the extracellular linkers of the Kv channels, which electrostatically affect the charged amino-acid residues of the voltage sensor S4. Extracellular cations shift the conductance-versus-voltage curve, G(V), by interfering with these extracellular charges. We have explored these issues by analyzing the effects of the divalent strontium ion (Sr(2+)) on the voltage dependence of the G(V) curves of wild-type and chimeric Kv channels expressed in Xenopus oocytes, using the voltage-clamp technique. Out of seven Kv channels, Kv1.2 was found to be most sensitive to Sr(2+) (50 mM shifted G(V) by +21.7 mV), and Kv2.1 to be the least sensitive (+7.8 mV). Experiments on 25 chimeras, constructed from Kv1.2 and Kv2.1, showed that the large Sr(2+)-induced G(V) shift of Kv1.2 can be transferred to Kv2.1 by exchanging the extracellular linker between S3 and S4 (L3/4) in combination with either the extracellular linker between S5 and the pore (L5/P) or that between the pore and S6 (LP/6). The effects of the linker substitutions were nonadditive, suggesting specific structural interactions. The free energy of these interactions was ∼20 kJ/mol, suggesting involvement of hydrophobic interactions and/or hydrogen bonds. Using principles from double-layer theory we derived an approximate linear equation (relating the voltage shifts to altered ionic strength), which proved to well match experimental data, suggesting that Sr(2+) acts on these channels mainly by screening surface charges. Taken together, these results highlight the extracellular surface potential at the voltage sensor as an important determinant of the channels' voltage dependence, making the extracellular linkers essential targets for evolutionary selection.

  14. Characterisation of the VELO High Voltage System

    CERN Document Server

    Rakotomiaramanana, B; Eklund, L

    2008-01-01

    The high voltage system supplies the bias voltage to the 88 silicon sensors which comprise the LHCb Vertex Locator (VELO). This note describes the results of the tests which have been performed on the hardware of the high voltage system of the VELO. Each individual test detailed in this note corresponds to a specific requirement of the system. These requirements arise primarily from ensuring the safety of the silicon sensors and the quality of the data taken from the VELO modules. The tests performed are in four categories: normal operation of the high voltage system; vercation of its stability under operation; discussion of its behaviour in failure modes; and details of operation at low voltage. Noteworthy issues, identified through the tests, include the behaviour of the high voltage modules at voltages below 9V, the current limit that can be applied during ramping of the voltage, and the speed with which the voltage is cut during failures of the system. The results of these tests provide high confidence th...

  15. Characterisation of the VELO High Voltage System

    CERN Document Server

    Rakotomiaramanana, B; Parkes, C; Eklund, L

    2008-01-01

    The high voltage system supplies the bias voltage to the 88 silicon sensors which comprise the LHCb Vertex Locator (VELO). This note describes the results of the tests which have been performed on the hardware of the high voltage system of the VELO. Each individual test detailed in this note corresponds to a specific requirement of the system. These requirements arise primarily from ensuring the safety of the silicon sensors and the quality of the data taken from the VELO modules. The tests performed are in four categories: normal operation of the high voltage system; verification of its stability under operation; discussion of its behaviour in failure modes; and details of operation at low voltage. Noteworthy issues, identified through the tests, include the behaviour of the high voltage modules at voltages below 9V, the current limit that can be applied during ramping of the voltage, and the speed with which the voltage is cut during failures of the system. The results of these tests provide high confidence...

  16. Beta-scorpion toxin effects suggest electrostatic interactions in domain II of voltage-dependent sodium channels. : Electrostatic interactions between segments IIS2, IIS3 and IIS4 of Na+ channel.

    OpenAIRE

    Mantegazza, Massimo; Cestèle, Sandrine

    2005-01-01

    International audience; Beta-scorpion toxins specifically modulate the voltage dependence of sodium channel activation by acting through a voltage-sensor trapping model. We used mutagenesis, functional analysis and the action of beta-toxin as tools to investigate the existence and role in channel activation of molecular interactions between the charged residues of the S2, S3 and S4 segments in domain II of sodium channels. Mutating to arginine the acidic residues of the S2 and S3 transmembran...

  17. PIP₂-dependent coupling is prominent in Kv7.1 due to weakened interactions between S4-S5 and S6.

    Science.gov (United States)

    Kasimova, Marina A; Zaydman, Mark A; Cui, Jianmin; Tarek, Mounir

    2015-01-06

    Among critical aspects of voltage-gated potassium (Kv) channels' functioning is the effective communication between their two composing domains, the voltage sensor (VSD) and the pore. This communication, called coupling, might be transmitted directly through interactions between these domains and, as recently proposed, indirectly through interactions with phosphatidylinositol-4,5-bisphosphate (PIP₂), a minor lipid of the inner plasma membrane leaflet. Here, we show how the two components of coupling, mediated by protein-protein or protein-lipid interactions, both contribute in the Kv7.1 functioning. On the one hand, using molecular dynamics simulations, we identified a Kv7.1 PIP₂ binding site that involves residues playing a key role in PIP₂-dependent coupling. On the other hand, combined theoretical and experimental approaches have shown that the direct interaction between the segments of the VSD (S4-S5) and the pore (S6) is weakened by electrostatic repulsion. Finally, we conclude that due to weakened protein-protein interactions, the PIP2-dependent coupling is especially prominent in Kv7.1.

  18. PIP2-dependent coupling is prominent in Kv7.1 due to weakened interactions between S4-S5 and S6

    Science.gov (United States)

    Kasimova, Marina A.; Zaydman, Mark A.; Cui, Jianmin; Tarek, Mounir

    2015-01-01

    Among critical aspects of voltage-gated potassium (Kv) channels' functioning is the effective communication between their two composing domains, the voltage sensor (VSD) and the pore. This communication, called coupling, might be transmitted directly through interactions between these domains and, as recently proposed, indirectly through interactions with phosphatidylinositol-4,5-bisphosphate (PIP2), a minor lipid of the inner plasma membrane leaflet. Here, we show how the two components of coupling, mediated by protein-protein or protein-lipid interactions, both contribute in the Kv7.1 functioning. On the one hand, using molecular dynamics simulations, we identified a Kv7.1 PIP2 binding site that involves residues playing a key role in PIP2-dependent coupling. On the other hand, combined theoretical and experimental approaches have shown that the direct interaction between the segments of the VSD (S4-S5) and the pore (S6) is weakened by electrostatic repulsion. Finally, we conclude that due to weakened protein-protein interactions, the PIP2-dependent coupling is especially prominent in Kv7.1.

  19. Super-Yang-Mills theories on S4 x R

    CERN Document Server

    Kim, Jungmin; Lee, Kimyeong; Park, Jaemo

    2014-01-01

    We construct super-Yang-Mills theories on S4 x R, S4 x S1 and S4 x interval with the field content of maximal SYM, coupled to boundary degrees in the last case. These theories provide building blocks of the `5d uplifts' of gauge theories on S4, obtained by compactifying the 6d (2,0) theory. We pay special attention to the N=2* theory on S4. We also explain how to construct maximal SYM on S5 x R, and clarify when SYM theories can be put on S^n x R.

  20. Steric hindrance between S4 and S5 of the KCNQ1/KCNE1 channel hampers pore opening.

    Science.gov (United States)

    Nakajo, Koichi; Kubo, Yoshihiro

    2014-06-12

    In voltage-gated K(+) channels, membrane depolarization induces an upward movement of the voltage-sensing domains (VSD) that triggers pore opening. KCNQ1 is a voltage-gated K(+) channel and its gating behaviour is substantially modulated by auxiliary subunit KCNE proteins. KCNE1, for example, markedly shifts the voltage dependence of KCNQ1 towards the positive direction and slows down the activation kinetics. Here we identify two phenylalanine residues on KCNQ1, Phe232 on S4 (VSD) and Phe279 on S5 (pore domain) to be responsible for the gating modulation by KCNE1. Phe232 collides with Phe279 during the course of the VSD movement and hinders KCNQ1 channel from opening in the presence of KCNE1. This steric hindrance caused by the bulky amino-acid residues destabilizes the open state and thus shifts the voltage dependence of KCNQ1/KCNE1 channel.

  1. Thermodynamic and kinetic properties of amino-terminal and S4-S5 loop HERG channel mutants under steady-state conditions.

    Science.gov (United States)

    Alonso-Ron, Carlos; de la Peña, Pilar; Miranda, Pablo; Domínguez, Pedro; Barros, Francisco

    2008-05-15

    Gating kinetics and underlying thermodynamic properties of human ether-a-go-go-related gene (HERG) K(+) channels expressed in Xenopus oocytes were studied using protocols able to yield true steady-state kinetic parameters. Channel mutants lacking the initial 16 residues of the amino terminus before the conserved eag/PAS region showed significant positive shifts in activation voltage dependence associated with a reduction of z(g) values and a less negative DeltaG(o), indicating a deletion-induced displacement of the equilibrium toward the closed state. Conversely, a negative shift and an increased DeltaG(o), indicative of closed-state destabilization, were observed in channels lacking the amino-terminal proximal domain. Furthermore, accelerated activation and deactivation kinetics were observed in these constructs when differences in driving force were considered, suggesting that the presence of distal and proximal amino-terminal segments contributes in wild-type channels to specific chemical interactions that raise the energy barrier for activation. Steady-state characteristics of some single point mutants in the intracellular loop linking S4 and S5 helices revealed a striking parallelism between the effects of these mutations and those of the amino-terminal modifications. Our data indicate that in addition to the recognized influence of the initial amino-terminus region on HERG deactivation, this cytoplasmic region also affects activation behavior. The data also suggest that not only a slow movement of the voltage sensor itself but also delaying its functional coupling to the activation gate by some cytoplasmic structures possibly acting on the S4-S5 loop may contribute to the atypically slow gating of HERG.

  2. Experimental validation of a high voltage pulse measurement method.

    Energy Technology Data Exchange (ETDEWEB)

    Cular, Stefan; Patel, Nishant Bhupendra; Branch, Darren W.

    2013-09-01

    This report describes X-cut lithium niobates (LiNbO3) utilization for voltage sensing by monitoring the acoustic wave propagation changes through LiNbO3 resulting from applied voltage. Direct current (DC), alternating current (AC) and pulsed voltage signals were applied to the crystal. Voltage induced shift in acoustic wave propagation time scaled quadratically for DC and AC voltages and linearly for pulsed voltages. The measured values ranged from 10 - 273 ps and 189 ps 2 ns for DC and non-DC voltages, respectively. Data suggests LiNbO3 has a frequency sensitive response to voltage. If voltage source error is eliminated through physical modeling from the uncertainty budget, the sensors U95 estimated combined uncertainty could decrease to ~0.025% for DC, AC, and pulsed voltage measurements.

  3. The Voltage-Dependent Anion Channel 1 (AtVDAC1 Negatively Regulates Plant Cold Responses during Germination and Seedling Development in Arabidopsis and Interacts with Calcium Sensor CBL1

    Directory of Open Access Journals (Sweden)

    Zhi-Yong Li

    2013-01-01

    Full Text Available The voltage-dependent anion channel (VDAC, a highly conserved major mitochondrial outer membrane protein, plays crucial roles in energy metabolism and metabolite transport. However, knowledge about the roles of the VDAC family in plants is limited. In this study, we investigated the expression pattern of VDAC1 in Arabidopsis and found that cold stress promoted the accumulation of VDAC1 transcripts in imbibed seeds and mature plants. Overexpression of VDAC1 reduced tolerance to cold stress in Arabidopsis. Phenotype analysis of VDAC1 T-DNA insertion mutant plants indicated that a vdac1 mutant line had faster germination kinetics under cold treatment and showed enhanced tolerance to freezing. The yeast two-hybrid system revealed that VDAC1 interacts with CBL1, a calcium sensor in plants. Like the vdac1, a cbl1 mutant also exhibited a higher seed germination rate. We conclude that both VDAC1 and CBL1 regulate cold stress responses during seed germination and plant development.

  4. Dual Regulation of Voltage-Sensitive Ion Channels by PIP(2).

    Science.gov (United States)

    Rodríguez-Menchaca, Aldo A; Adney, Scott K; Zhou, Lei; Logothetis, Diomedes E

    2012-01-01

    Over the past 16 years, there has been an impressive number of ion channels shown to be sensitive to the major phosphoinositide in the plasma membrane, phosphatidylinositol 4,5-bisphosphate (PIP(2)). Among them are voltage-gated channels, which are crucial for both neuronal and cardiac excitability. Voltage-gated calcium (Cav) channels were shown to be regulated bidirectionally by PIP(2). On one hand, PIP(2) stabilized their activity by reducing current rundown but on the other hand it produced a voltage-dependent inhibition by shifting the activation curve to more positive voltages. For voltage-gated potassium (Kv) channels PIP(2) was first shown to prevent N-type inactivation regardless of whether the fast inactivation gate was part of the pore-forming α subunit or of an accessory β subunit. Careful examination of the effects of PIP(2) on the activation mechanism of Kv1.2 has shown a similar bidirectional regulation as in the Cav channels. The two effects could be distinguished kinetically, in terms of their sensitivities to PIP(2) and by distinct molecular determinants. The rightward shift of the Kv1.2 voltage dependence implicated basic residues in the S4-S5 linker and was consistent with stabilization of the inactive state of the voltage sensor. A third type of a voltage-gated ion channel modulated by PIP(2) is the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel. PIP(2) has been shown to enhance the opening of HCN channels by shifting their voltage-dependent activation toward depolarized potentials. The sea urchin HCN channel, SpIH, showed again a PIP(2)-mediated bidirectional effect but in reverse order than the depolarization-activated Cav and Kv channels: a voltage-dependent potentiation, like the mammalian HCN channels, but also an inhibition of the cGMP-induced current activation. Just like the Kv1.2 channels, distinct molecular determinants underlied the PIP(2) dual effects on SpIH, with the proximal C-terminus implicated in the

  5. Dual Regulation of Voltage-Sensitive Ion Channels by PIP2

    Directory of Open Access Journals (Sweden)

    Aldo A Rodríguez Menchaca

    2012-09-01

    Full Text Available Over the past 16 years, there has been an impressive number of ion channels shown to be sensitive to the major phosphoinositide in the plasma membrane, phosphatidilinositol 4,5-bisphosphate (PIP2. Among them are voltage-gated channels, which are crucial for both neuronal and cardiac excitability. Voltage-gated calcium (Cav channels were shown to be regulated bidirectionally by PIP2. On one hand, PIP2 stabilized their activity by reducing current rundown but on the other hand it produced a voltage-dependent inhibition by shifting the activation curve to more positive voltages. For voltage-gated potassium (Kv channels PIP2 was first shown to prevent N-type inactivation. Careful examination of the effects of PIP2 on the activation mechanism of Kv1.2 has shown a similar bidirectional regulation as in the Cav channels. The two effects could be distinguished kinetically, in terms of their sensitivities to PIP2 and by distinct molecular determinants. The rightward shift of the Kv1.2 voltage dependence implicated basic residues in the S4-S5 linker and was consistent with stabilization of the inactive state of the voltage sensor. A third type of a voltage-gated ion channel modulated by PIP2 is the hyperpolarization-activated cyclic nucleotide-gated (HCN channel. PIP2 has been shown to enhance the opening of HCN channels by shifting their voltage-dependent activation toward depolarized potentials. The sea urchin HCN channel, SpIH, showed again a PIP2-mediated bidirectional effect but in reverse order than the depolarization-activated Cav and Kv channels: a voltage-dependent potentiation, like the mammalian HCN channels, but also an inhibition of the cGMP-induced current activation. Just like the Kv1.2 channels, distinct molecular determinants underlied the PIP2 dual effects on SpIH channels. The dual regulation of these very different ion channels, all of which are voltage dependent, points to conserved mechanisms of regulation of these channels by PIP2.

  6. 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.

  7. External Force Damage Simulation of Submarine High-voltage Cable Based on Distributed Fiber Optic Sensor Technology%基于分布式光纤传感技术的高压海底电缆外力损坏仿真

    Institute of Scientific and Technical Information of China (English)

    陆莹; 黄辉

    2012-01-01

    高压海底电缆的安全稳定运行对于海上能源的开发具有重要的作用,海缆电缆的损坏主要由外力引起,针对分布式光纤传感器在线监测高压海底电缆运行状况的方法,利用有限元软件ANSYS建立XLPE高压海底电缆模型,仿真分析海底电缆受到外力损坏时,内部物理量的变化,为分布式光纤传感器在线监测高压海底电缆运行状态提供参考。%Safety and stable operation of submarine high-voltage cable has played an important role in the development of Marine energy. However, submarine high-voltage cable was mainly damaged by external forces. According to the method for operation state of submarine high-voltage cable using on-line monitoring technology based on distributed fiber optic sensor, the model of the XLPE submarine high-voltage cable was gained by using finite element software ANSYS. Then, based on the model, the change of internal physical quantities were researched ,when submarine high-voltage cable was damaged by external force, with the function to provide the practical reference for running state of submarine high-voltage cable monitoring on-line based on distributed fiber optic sensor.

  8. Giant magnetoimpedance intrinsic impedance and voltage sensitivity of rapidly solidified Co{sub 66}Fe{sub 2}Cr{sub 4}Si{sub 13}B{sub 15} amorphous wire for highly sensitive sensors applications

    Energy Technology Data Exchange (ETDEWEB)

    Das, Tarun K.; Mandal, Sushil K. [CSIR - National Metallurgical Laboratory, NDE and Magnetic Materials Group, MST Division, Jamshedpur (India); Banerji, Pallab [Indian Institute of Technology, Kharagpur, Materials Science Centre, Kharagpur (India)

    2016-11-15

    We report a systematic study of the influence of wire length, L, dependence of giant magneto-impedance (GMI) sensitivity of Co{sub 66}Fe{sub 2}Cr{sub 4}Si{sub 13}B{sub 15} soft magnetic amorphous wire of diameter ∝ 100 μm developed by in-water quenching technique. The magnetization behaviour (hysteresis loops) of the wire with different length (L = 1, 2, 3, 5, 8 and 10 cm) has been evaluated by fuxmetric induction method. It was observed that the behaviour of the hysteresis loops change drastically with the wire length, being attributed to the existence of a critical length, L{sub C}, found to be around 3 cm. GMI measurements have been taken using automated GMI measurement system and the GMI sensitivities in terms of intrinsic impedance sensitivity (S{sub Ω/Am}{sup -1}) and voltage sensitivity (S{sub V/Am}{sup -1}) of the wire have been evaluated under optimal bias field and excitation current. It was found that the maximum (S{sub Ω/Am}{sup -1}){sub max} ∼ 0.63 Ω/kAm{sup -1}/cm and (S{sub V/Am}{sup -1}){sub max} ∼ 3.10 V/kAm{sup -1}/cm were achieved at a critical length L{sub C} ∝ 3 cm of the wire for an AC current of 5 mA and a frequency of 5 MHz. These findings provide crucial insights for optimization of the geometrical dimensions of magnetic sensing elements and important practical guidance for designing high sensitive GMI sensors. The relevant combinations of magnetic material parameters and operating conditions that optimize the sensitivity are highlighted. (orig.)

  9. Doctor-bladed Cu2ZnSnS4 light absorption layer for low-cost solar cell application

    Institute of Scientific and Technical Information of China (English)

    Chen Qin-Miao; Li Zhen-Qing; Ni Yi; Cheng Shu-Yi; Dou Xiao--Ming

    2012-01-01

    The doctor-blade method is investigated for the preparation of Cu2ZnSnS4 films for low-cost solar cell application.Cu2ZnSnS4 precursor powder,the main raw material for the doctor-blade paste,is synthesized by a simple ball-milling process.The doctor-bladed Cu2ZnSnS4 films are annealed in N2 ambient under various conditions and characterized by X-ray diffraction,ultravio1lent/vis spectrophotometry,scanning electron microscopy,and current-voltage (J-V)meansurement. Our experimental results indicate that (i) the X-ray diffraction peaks of the Cu2ZnSnS4 precursor powder each show a red shift of about 0.4°; (ii) the high-temperature annealing process can effectively improve the crystallinity of the doctor-bladed Cu2ZnSnS4,whereas an overlong annealing introduces defects; (iii) the band gap value of the doctor-bladed Cu2ZnSnS4 is around 1.41 eV; (iv) the short-circuit current density,the open-circuit voltage,the fill factor,and the efficiency of the best Cu2ZnSnS4 solar cell obtained with the superstrate structure of fluorine-doped tin oxide glass/TiO2/In2S3/Cu2ZnSnS4/Mo are 7.82 mA/cm2,240 mV,0.29,and 0.55%,respectively.

  10. Duration of Acute and Chronic Toxicity Testing in Animals (ICH S4A and S4B)

    DEFF Research Database (Denmark)

    Spindler, Per; Van Cauteren, Herman

    2013-01-01

    To support approval of pharmaceuticals for long term use in humans it is required that product safety is supported by acute and chronic toxicity studies in rodents and non-rodents. The duration of acute toxicity studies (S4A) and chronic rodent studies (S4B) were harmonised between the three ICH ...

  11. Methods and apparatuses for low-noise magnetic sensors

    KAUST Repository

    Kosel, Jurgen

    2015-10-20

    Magnetic sensors are disclosed, as well as methods for fabricating and using the same. In some embodiments, an EMR effect sensor includes a semiconductor layer. In some embodiments, the EMR effect sensor may include a conductive layer substantially coupled to the semiconductor layer. In some embodiments, the EMR effect sensor may include a first voltage lead coupled to the semiconductor layer. In some embodiments, the first voltage lead may be configured to provide a voltage for measurement by a voltage measurement circuit. In some embodiments, the EMR effect sensor may include a second voltage lead coupled to the conductive layer. In some embodiments, the second voltage lead may be configured to provide a voltage for measurement by a voltage measurement circuit. Embodiments of a Hall effect sensor having the same or similar structure are also disclosed.

  12. The cytoplasmic coiled-coil mediates cooperative gating temperature sensitivity in the voltage-gated H(+) channel Hv1.

    Science.gov (United States)

    Fujiwara, Yuichiro; Kurokawa, Tatsuki; Takeshita, Kohei; Kobayashi, Megumi; Okochi, Yoshifumi; Nakagawa, Atsushi; Okamura, Yasushi

    2012-05-08

    Hv1/VSOP is a dimeric voltage-gated H(+) channel in which the gating of one subunit is reportedly coupled to that of the other subunit within the dimer. The molecular basis for dimer formation and intersubunit coupling, however, remains unknown. Here we show that the carboxy terminus ends downstream of the S4 voltage-sensor helix twist in a dimer coiled-coil architecture, which mediates cooperative gating. We also show that the temperature-dependent activation of H(+) current through Hv1/VSOP is regulated by thermostability of the coiled-coil domain, and that this regulation is altered by mutation of the linker between S4 and the coiled-coil. Cooperative gating within the dimer is also dependent on the linker structure, which circular dichroism spectrum analysis suggests is α-helical. Our results indicate that the cytoplasmic coiled-coil strands form continuous α-helices with S4 and mediate cooperative gating to adjust the range of temperatures over which Hv1/VSOP operates.

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

    Science.gov (United States)

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

    2016-07-05

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

  14. Transient Voltage Recorder

    Science.gov (United States)

    Medelius, Pedro J. (Inventor); Simpson, Howard J. (Inventor)

    2002-01-01

    A voltage transient recorder can detect lightning induced transient voltages. The recorder detects a lightning induced transient voltage and adjusts input amplifiers to accurately record transient voltage magnitudes. The recorder stores voltage data from numerous monitored channels, or devices. The data is time stamped and can be output in real time, or stored for later retrieval. The transient recorder, in one embodiment, includes an analog-to-digital converter and a voltage threshold detector. When an input voltage exceeds a pre-determined voltage threshold, the recorder stores the incoming voltage magnitude and time of arrival. The recorder also determines if its input amplifier circuits clip the incoming signal or if the incoming signal is too low. If the input data is clipped or too low, the recorder adjusts the gain of the amplifier circuits to accurately acquire subsequent components of the lightning induced transients.

  15. Molecular mechanism of voltage sensing in voltage-gated proton channels

    Science.gov (United States)

    Rebolledo, Santiago; Perez, Marta E.

    2013-01-01

    Voltage-gated proton (Hv) channels play an essential role in phagocytic cells by generating a hyperpolarizing proton current that electrically compensates for the depolarizing current generated by the NADPH oxidase during the respiratory burst, thereby ensuring a sustained production of reactive oxygen species by the NADPH oxidase in phagocytes to neutralize engulfed bacteria. Despite the importance of the voltage-dependent Hv current, it is at present unclear which residues in Hv channels are responsible for the voltage activation. Here we show that individual neutralizations of three charged residues in the fourth transmembrane domain, S4, all reduce the voltage dependence of activation. In addition, we show that the middle S4 charged residue moves from a position accessible from the cytosolic solution to a position accessible from the extracellular solution, suggesting that this residue moves across most of the membrane electric field during voltage activation of Hv channels. Our results show for the first time that the charge movement of these three S4 charges accounts for almost all of the measured gating charge in Hv channels. PMID:23401575

  16. Holography for ${\\cal N}=2^*$ on $S^4$

    CERN Document Server

    Bobev, Nikolay; Freedman, Daniel Z; Pufu, Silviu S

    2013-01-01

    We find the gravity dual of $\\mathcal{N}=2^*$ super-Yang-Mills theory on $S^4$ and use holography to calculate the universal contribution to the corresponding $S^4$ free energy at large $N$ and large 't Hooft coupling. Our result matches the expression previously computed using supersymmetric localization in the field theory. This match represents a non-trivial precision test of holography in a non-conformal, Euclidean signature setting.

  17. CMB-S4 Science Book, First Edition

    OpenAIRE

    Abazajian, Kevork N.; Adshead, Peter; Ahmed, Zeeshan; Allen, Steven W.; Alonso, David; Arnold, Kam S.; Baccigalupi, Carlo; Bartlett, James G.; Battaglia, Nicholas; Benson, Bradford A.; Bischoff, Colin A.; Borrill, Julian; Buza, Victor; Calabrese, Erminia; Caldwell, Robert

    2016-01-01

    This book lays out the scientific goals to be addressed by the next-generation ground-based cosmic microwave background experiment, CMB-S4, envisioned to consist of dedicated telescopes at the South Pole, the high Chilean Atacama plateau and possibly a northern hemisphere site, all equipped with new superconducting cameras. CMB-S4 will dramatically advance cosmological studies by crossing critical thresholds in the search for the B-mode polarization signature of primordial gravitational waves...

  18. S4 as a natural flavor symmetry for lepton mixing

    CERN Document Server

    Bazzocchi, Federica

    2008-01-01

    Group theoretical motivations seem to indicate the discrete symmetry S4 as the minimal flavour symmetry compatible with tribimaximal neutrino mixing. We prove in a model independent way that indeed S4 can realize exact TriBimaximal mixing through different symmetry breaking patterns. We present two models in which lepton TriBimaximal mixing is realized in different ways and for each one we discuss the superpotential that leads to the correct breaking of the flavor symmetry.

  19. Variable Rail Voltage Control of a Brushless DC (BLDC) Motor

    Science.gov (United States)

    2013-01-01

    Variable Rail Voltage Control of a Brushless DC (BLDC) Motor by Yuan Chen, Joseph Conroy, and William Nothwang ARL-TR-6308 January 2013...TR-6308 January 2013 Variable Rail Voltage Control of a Brushless DC (BLDC) Motor Yuan Chen, Joseph Conroy, and William Nothwang Sensors...DATES COVERED (From - To) 4. TITLE AND SUBTITLE Variable Rail Voltage Control of a Brushless DC (BLDC) Motor 5a. CONTRACT NUMBER 5b. GRANT

  20. Automatic voltage imbalance detector

    Science.gov (United States)

    Bobbett, Ronald E.; McCormick, J. Byron; Kerwin, William J.

    1984-01-01

    A device for indicating and preventing damage to voltage cells such as galvanic cells and fuel cells connected in series by detecting sequential voltages and comparing these voltages to adjacent voltage cells. The device is implemented by using operational amplifiers and switching circuitry is provided by transistors. The device can be utilized in battery powered electric vehicles to prevent galvanic cell damage and also in series connected fuel cells to prevent fuel cell damage.

  1. Mixed voltage VLSI design

    Science.gov (United States)

    Panwar, Ramesh; Rennels, David; Alkalaj, Leon

    1993-01-01

    A technique for minimizing the power dissipated in a Very Large Scale Integration (VLSI) chip by lowering the operating voltage without any significant penalty in the chip throughput even though low voltage operation results in slower circuits. Since the overall throughput of a VLSI chip depends on the speed of the critical path(s) in the chip, it may be possible to sustain the throughput rates attained at higher voltages by operating the circuits in the critical path(s) with a high voltage while operating the other circuits with a lower voltage to minimize the power dissipation. The interface between the gates which operate at different voltages is crucial for low power dissipation since the interface may possibly have high static current dissipation thus negating the gains of the low voltage operation. The design of a voltage level translator which does the interface between the low voltage and high voltage circuits without any significant static dissipation is presented. Then, the results of the mixed voltage design using a greedy algorithm on three chips for various operating voltages are presented.

  2. Enhancing Roentgen Sensitivity of Gold-Doped CdIn2S4 Thiospinel for X-Ray Detection Applications

    Directory of Open Access Journals (Sweden)

    Solmaz N. Mustafaeva

    2015-01-01

    Full Text Available The single crystals CdIn2S4Au were grown from preliminarily synthesized polycrystals by the method of chemical transport reactions in a closed volume with iodine used as a carrier. The influence of doping CdIn2S4 single crystals by gold (3 mol % on their X-ray dosimetric parameters is studied. It is found that the X-ray sensitivity coefficients of CdIn2S4Au crystals increase 6–8 times compared with undoped CdIn2S4 at effective radiation hardness Va= 25–50 keV and dose rate E=0.75–78.05 R/min. Moreover, the persistence of the crystal characteristics completely disappears and the supple voltage of a CdIn2S4Au roentgen detector decreases threefold. The dependence of the steady X-ray-induced current in CdIn2S4Au on the X-ray dose is described by linear law. The studied crystals have a rather high room-temperature X-ray sensitivity (K=2·10-9–1.5·10-8 (A·min/(R·V and are attractive as materials for X-ray detectors.

  3. Non-commutative Field Theory on S^4

    CERN Document Server

    Nakayama, R; Nakayama, Ryuichi; Shimono, Yusuke

    2004-01-01

    In the previous paper (hep-th/0402010) we proposed a matrix configuration for a non-commutative S^4 (NC4S) and constructed a non-commutative (star) product for field theories on NC4S. This star product and the functions on NC4S turned out to be singular (ambiguous) on a circle on S^4. In the present paper we will show that any matrix can be expanded in terms of the matrix configuration representing NC4S just like any matrix can be expanded into symmetrized products of the matrix configuration for non-commutative S^2. Then we will show that the singularities of the functions on S^4 and the star product can be removed by covering the (commutative) manifold by coordinate neighborhoods and performing appropriate coordinate transformations. Finally a scalar field theory on NC4S is constructed. Our matrix configuration describes two S^4's joined at the circle and the Matrix theory action contains a projection matrix inside the trace to restrict the space of matrices to that for one S^4.

  4. Mapping of scorpion toxin receptor sites at voltage-gated sodium channels.

    Science.gov (United States)

    Gurevitz, Michael

    2012-09-15

    Scorpion alpha and beta toxins interact with voltage-gated sodium channels (Na(v)s) at two pharmacologically distinct sites. Alpha toxins bind at receptor site-3 and inhibit channel inactivation, whereas beta toxins bind at receptor site-4 and shift the voltage-dependent activation toward more hyperpolarizing potentials. The two toxin classes are subdivided to distinct pharmacological groups according to their binding preferences and ability to compete for the receptor sites at Na(v) subtypes. To elucidate the toxin-channel surface of interaction at both receptor sites and clarify the molecular basis of varying toxin preferences, an efficient bacterial system for their expression in recombinant form was established. Mutagenesis accompanied by toxicity, binding and electrophysiological assays, in parallel to determination of the three-dimensional structure using NMR and X-ray crystallography uncovered a bipartite bioactive surface in toxin representatives of all pharmacological groups. Exchange of external loops between the mammalian brain channel rNa(v)1.2a and the insect channel DmNa(v)1 highlighted channel regions involved in the varying sensitivity to assorted toxins. In parallel, thorough mutagenesis of channel external loops illuminated points of putative interaction with the toxins. Amino acid substitutions at external loops S1-S2 and S3-S4 of the voltage sensor module in domain II of rNa(v)1.2a had prominent impact on the activity of the beta-toxin Css4 (from Centruroides suffusus suffusus), and substitutions at external loops S1-S2 and S3-S4 of the voltage sensor module in domain IV affected the activity of the alpha-toxin Lqh2 (from Leiurus quinquestriatus hebraeus). Rosetta modeling of toxin-Na(v) interaction using the voltage sensor module of the potassium channel as template raises commonalities in the way alpha and beta toxins interact with the channel. Css4 interacts with rNa(v)1.2a at a crevice between S1-S2 and S3-S4 transmembrane segments in domain

  5. Voltage-gated proton (H(v)1) channels, a singular voltage sensing domain.

    Science.gov (United States)

    Castillo, Karen; Pupo, Amaury; Baez-Nieto, David; Contreras, Gustavo F; Morera, Francisco J; Neely, Alan; Latorre, Ramon; Gonzalez, Carlos

    2015-11-14

    The main role of voltage-gated proton channels (Hv1) is to extrude protons from the intracellular milieu when, mediated by different cellular processes, the H(+) concentration increases. Hv1 are exquisitely selective for protons and their structure is homologous to the voltage sensing domain (VSD) of other voltage-gated ion channels like sodium, potassium, and calcium channels. In clear contrast to the classical voltage-dependent channels, Hv1 lacks a pore domain and thus permeation necessarily occurs through the voltage sensing domain. Hv1 channels are activated by depolarizing voltages, and increases in internal proton concentration. It has been proposed that local conformational changes of the transmembrane segment S4, driven by depolarization, trigger the molecular rearrangements that open Hv1. However, it is still unclear how the electromechanical coupling is achieved between the VSD and the potential pore, allowing the proton flux from the intracellular to the extracellular side. Here we provide a revised view of voltage activation in Hv1 channels, offering a comparative scenario with other voltage sensing channels domains.

  6. Holography for $\\mathcal{N}=1^*$ on $S^4$

    CERN Document Server

    Bobev, Nikolay; Kol, Uri; Olson, Timothy; Pufu, Silviu S

    2016-01-01

    We construct the five-dimensional supergravity dual of the $\\mathcal{N}=1^*$ mass deformation of the $\\mathcal{N} =4$ supersymmetric Yang-Mills theory on $S^4$ and use it to calculate the universal contribution to the corresponding $S^4$ free energy at large 't Hooft coupling in the planar limit. The holographic RG flow solutions are smooth and preserve four supercharges. As a novel feature compared to the holographic duals of $\\mathcal{N} = 1^*$ on $\\mathbb{R}^4$, in our backgrounds the five-dimensional dilaton has a non-trivial profile, and the gaugino condensate is fixed in terms of the mass-deformation parameters. Important aspects of the analysis involve characterizing the ambiguities in the partition function of non-conformal $\\mathcal{N}=1$ supersymmetric theories on $S^4$ as well as the action of S-duality on the $\\mathcal{N}=1^*$ theory.

  7. Neutrino Mixings and the S4 Discrete Flavour Symmetry

    CERN Document Server

    Bazzocchi, Federica

    2012-01-01

    Discrete non-Abelian Symmetries have been extensively used to reproduce the lepton mixings. In particular, the S4 group turned out to be suitable to describe predictive mixing patterns, such as the well-known Tri-Bimaximal and the Bimaximal schemes, which all represent possible first approximations of the experimental lepton mixing matrix. We review the main application of the S4 discrete group as a flavour symmetry, first dealing with the formalism and later with the phenomenological implications. In particular, we summarize the main features of flavour models based on S4, commenting on their ability in reproducing a reactor angle in agreement with the recent data and on their predictions for lepton flavour violating transitions.

  8. Is NiCo2S4 really a semiconductor?

    KAUST Repository

    Xia, Chuan

    2015-08-31

    NiCo2S4 is a technologically important electrode material that has recently achieved remarkable performance in pseu-docapacitor, catalysis, and dye-synthesized solar cell applications.[1-5] Essentially, all reports on this material have pre-sumed it to be semiconducting, like many of the chalcogenides, with a reported band-gap in the range of 1.2-1.7 eV.[6,7] In this report, we have conducted detailed experimental and theoretical studies, most of which done for the first time, which overwhelmingly show that NiCo2S4 is in fact a metal. We have also calculated the Raman spectrum of this mate-rial and experimentally verified it for the first time, hence clarifying inconsistent Raman spectra reports. Some of the key results that support our conclusions include: (1) the measured carrier density in NiCo2S4 is 3.18×1022 cm-3, (2) Ni-Co2S4 has a room temperature resistivity of around 103 µΩ cm which increases with temperature, (3) NiCo2S4 exhibits a quadratic dependence of the magnetoresistance on magnetic field, (4) thermopower measurements show an extremely low Seebeck coefficient of 5 µV K-1, (5) first principles calculations confirm that NiCo2S4 is a metal. These results sug-gest that it is time to re-think the presumed semiconducting nature of this promising material. They also suggest that the metallic conductivity is another reason (besides the known significant redox activity) behind the excellent perfor-mance reported for this material.

  9. Synthesis of (3S,4R)-bengamide E

    Institute of Scientific and Technical Information of China (English)

    Qi Jun Liu; Hong Li; Shao Peng Chen; Guo Chun Zhou

    2011-01-01

    (3S,4R)-Bengamide E (2) was synthesized starting from D-glucono-δ-lactone (3) and the key deoxygenation step from 13 to 15 was achieved by the application of NaBH3CN and ZnI2. Compared with natural bengamide E (1), the synthetic compound (3S,4R)-bengamide E (2) was inactive against the cell growth of HUVEC and cancer cells. These data represent the significance of the stereochemistry at C-3 and C-4 of bengamides for structural recognition and binding with the target(s).

  10. Phenomenology of S_4 Flavor Symmetric extra U(1) model

    CERN Document Server

    Daikoku, Yasuhiro

    2013-01-01

    We study several phenomenologies of an E_6 inspired extra U(1) model with S_4 flavor symmetry. With the assignment of left-handed quarks and leptons to S_4-doublet, SUSY flavor problem is softened. As the extra Higgs bosons are neutrinophilic, baryon number asymmetry in the universe is realized by leptogenesis without causing gravitino overproduction. We find that the allowed region for the lightest chargino mass is given by 100-140 GeV, if the dark matter is a singlino dominated neutralino whose mass is about 36 GeV.

  11. Electrodeposited Cu2ZnSnS4 thin films

    CSIR Research Space (South Africa)

    Valdes, M

    2014-05-01

    Full Text Available Electrochimica Acta Vol. 128, pp 393-399 Electrodeposited Cu2ZnSnS4thin films M. Valdesa, M. Modibedib, M. Matheb, T. Hilliec,d, M. Vazqueza,∗ aDivisión Electroquimica y Corrosión, INTEMA, UNMdP-CONICET, J. B. Justo 4302 B7608FDQ Mar del Plata, Argentina...

  12. N=2 SUSY gauge theories on S^4

    CERN Document Server

    Hosomichi, Kazuo

    2016-01-01

    We review exact results in N=2 supersymmetric gauge theories defined on S^4 and its deformation. We first summarize the construction of rigid SUSY theories on curved backgrounds based on off-shell supergravity, then explain how to apply localization principle to supersymmetric path integrals. Closed formulae for partition function as well as expectation values of non-local BPS observables are presented.

  13. Cu7 S4 Nanosuperlattices with Greatly Enhanced Photothermal Efficiency.

    Science.gov (United States)

    Cui, Jiabin; Jiang, Rui; Xu, Suying; Hu, Gaofei; Wang, Leyu

    2015-09-02

    According to the simulation, the self-assembly of Cu7 S4 nanocrystals would enhance the photothermal conversion efficiency (PCE) because of the localized surface plasmon resonance effects, which is highly desirable for photothermal therapy (PTT). A new strategy to synthesize Cu7 S4 nanosuperlattices with greatly enhanced PCE up to 65.7% under irradiation of 808 nm near infrared light is reported here. By tuning the surface properties of Cu7 S4 nanocrystals during the synthesis via thermolysis of a new single precursor, dispersed nanoparticles (NPs), rod-like alignments, and nanosuperlattices are obtained, respectively. To explore their PTT applications, these hydrophobic nanostructures are transferred into water by coating with home-made amphiphilic polymer while maintaining their original structures. Under identical conditions, the PCE are 48.62% and 56.32% for dispersed NPs and rod-like alignments, respectively. As expected, when the nanoparticles are self-assembled into nanosuperlattices, the PCE is greatly enhanced up to 65.7%. This strong PCE, along with their excellent photothermal stability and good biocompatibility, renders these nanosuperlattices good candidates as PTT agents. In vitro photothermal ablation performances have undoubtedly proved the excellent PCE of our Cu7 S4 nanosuperlattices. This research offers a versatile and effective solution to get PTT agents with high photothermal efficiency.

  14. Synthesis and characterization of Cu2ZnSnS4 thin films by SILAR method

    Science.gov (United States)

    Mali, Sawanta S.; Shinde, Pravin S.; Betty, Chirayath A.; Bhosale, Popatrao N.; Oh, Young Woo; Patil, Pramod S.

    2012-06-01

    Semiconducting Cu2ZnSnS4 (CZTS) material has been receiving a great technological interest in the photovoltaic industry because of its low-cost non-toxic constituents, ideal direct band gap as a absorber layer and high absorption coefficient. CZTS thin films have been successfully deposited onto the fluorine-doped tin oxide/glass (glass/FTO) substrates coated glass substrates using successive ionic layer adsorption and reaction (SILAR) method and investigated for photoelectrochemical conversion (PEC) of light into electricity. The best solar cell sample showed an open-circuit voltage of 390 mV, a short-circuit current density of 636.9 μA/cm2, a fill factor of 0.62 and an efficiency of 0.396% under irradiation of 30 mW/cm2. Preliminary results obtained for solar cells fabricated with this material are promising.

  15. Duration of Acute and Chronic Toxicity Testing in Animals (ICH S4A and S4B)

    DEFF Research Database (Denmark)

    Spindler, Per; Van Cauteren, Herman

    2013-01-01

    for the ICH S4B guideline regarding the duration of non-rodent repeated dose toxicity studies is explained and lessons learned are discussed. Since the guideline was issued in 1997 changes occurred in e.g. the language of the European legislation, and the requirements for non-clinical studies to support...

  16. Technological Aspects: High Voltage

    CERN Document Server

    Faircloth, D C

    2013-01-01

    This paper covers the theory and technological aspects of high-voltage design for ion sources. Electric field strengths are critical to understanding high-voltage breakdown. The equations governing electric fields and the techniques to solve them are discussed. The fundamental physics of high-voltage breakdown and electrical discharges are outlined. Different types of electrical discharges are catalogued and their behaviour in environments ranging from air to vacuum are detailed. The importance of surfaces is discussed. The principles of designing electrodes and insulators are introduced. The use of high-voltage platforms and their relation to system design are discussed. The use of commercially available high-voltage technology such as connectors, feedthroughs and cables are considered. Different power supply technologies and their procurement are briefly outlined. High-voltage safety, electric shocks and system design rules are covered.

  17. Multimeric nature of voltage-gated proton channels

    OpenAIRE

    Koch, Hans P.; Kurokawa, Tatsuki; Okochi, Yoshifumi; Sasaki, Mari; Okamura, Yasushi; Larsson, H. Peter

    2008-01-01

    Voltage-gated potassium channels are comprised of four subunits, and each subunit has a pore domain and a voltage-sensing domain (VSD). The four pore domains assemble to form one single central pore, and the four individual VSDs control the gate of the pore. Recently, a family of voltage-gated proton channels, such as HV or voltage sensor only protein (VSOP), was discovered that contain a single VSD but no pore domain. It has been assumed that VSOP channels are monomeric and contain a single ...

  18. Mutations of the S4-S5 linker alter activation properties of HERG potassium channels expressed in Xenopus oocytes.

    Science.gov (United States)

    Sanguinetti, M C; Xu, Q P

    1999-02-01

    1. The structural basis for the activation gate of voltage-dependent K+ channels is not known, but indirect evidence has implicated the S4-S5 linker, the cytoplasmic region between the fourth and fifth transmembrane domains of the channel subunit. We have studied the effects of mutations in the S4-S5 linker of HERG (human ether-á-go-go-related gene), a human delayed rectifier K+ channel, in Xenopus oocytes. 2. Mutation of acidic residues (D540, E544) in the S4-S5 linker of HERG channels to neutral (Ala) or basic (Lys) residues accelerated the rate of channel deactivation. Most mutations greatly accelerated the rate of activation. However, E544K HERG channels activated more slowly than wild-type HERG channels. 3. Mutation of residues in the S4-S5 linker had little or no effect on fast inactivation, consistent with independence of HERG channel activation and inactivation 4. In response to large hyperpolarizations, D540K HERG channels can reopen into a state that is distinct from the normal depolarization-induced open state. It is proposed that substitution of a negatively charged Asp with the positively charged Lys disrupts a subunit interaction that normally stabilizes the channel in a closed state at negative transmembrane potentials. 5. The results indicate that the S4-S5 linker is a crucial component of the activation gate of HERG channels.

  19. Stray voltage mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Jamali, B.; Piercy, R.; Dick, P. [Kinetrics Inc., Toronto, ON (Canada). Transmission and Distribution Technologies

    2008-04-09

    This report discussed issues related to farm stray voltage and evaluated mitigation strategies and costs for limiting voltage to farms. A 3-phase, 3-wire system with no neutral ground was used throughout North America before the 1930s. Transformers were connected phase to phase without any electrical connection between the primary and secondary sides of the transformers. Distribution voltage levels were then increased and multi-grounded neutral wires were added. The earth now forms a parallel return path for the neutral current that allows part of the neutral current to flow continuously through the earth. The arrangement is responsible for causing stray voltage. Stray voltage causes uneven milk production, increased incidences of mastitis, and can create a reluctance to drink water amongst cows when stray voltages are present. Off-farm sources of stray voltage include phase unbalances, undersized neutral wire, and high resistance splices on the neutral wire. Mitigation strategies for reducing stray voltage include phase balancing; conversion from single to 3-phase; increasing distribution voltage levels, and changing pole configurations. 22 refs., 5 tabs., 13 figs.

  20. High voltage engineering

    CERN Document Server

    Rizk, Farouk AM

    2014-01-01

    Inspired by a new revival of worldwide interest in extra-high-voltage (EHV) and ultra-high-voltage (UHV) transmission, High Voltage Engineering merges the latest research with the extensive experience of the best in the field to deliver a comprehensive treatment of electrical insulation systems for the next generation of utility engineers and electric power professionals. The book offers extensive coverage of the physical basis of high-voltage engineering, from insulation stress and strength to lightning attachment and protection and beyond. Presenting information critical to the design, selec

  1. High voltage test techniques

    CERN Document Server

    Kind, Dieter

    2001-01-01

    The second edition of High Voltage Test Techniques has been completely revised. The present revision takes into account the latest international developments in High Voltage and Measurement technology, making it an essential reference for engineers in the testing field.High Voltage Technology belongs to the traditional area of Electrical Engineering. However, this is not to say that the area has stood still. New insulating materials, computing methods and voltage levels repeatedly pose new problems or open up methods of solution; electromagnetic compatibility (EMC) or components and systems al

  2. Mitigation of Unbalanced Voltage Sags and Voltage Unbalance in CIGRE Low Voltage Distribution Network

    OpenAIRE

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar; Cecati, Carlo

    2013-01-01

    Any problem with voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM) etc. can be used to mitigate the voltage problems in the distribution system. The voltage problems dealt with in this paper are to show how to mitigate unbalanced voltage sags and voltage unbalance in the CIGRE Low Voltage (LV) test network and net-works like this. The voltage unbala...

  3. CMB-S4 Science Book, First Edition

    CERN Document Server

    Abazajian, Kevork N; Ahmed, Zeeshan; Allen, Steven W; Alonso, David; Arnold, Kam S; Baccigalupi, Carlo; Bartlett, James G; Battaglia, Nicholas; Benson, Bradford A; Bischoff, Colin A; Borrill, Julian; Buza, Victor; Calabrese, Erminia; Caldwell, Robert; Carlstrom, John E; Chang, Clarence L; Crawford, Thomas M; Cyr-Racine, Francis-Yan; De Bernardis, Francesco; de Haan, Tijmen; Alighieri, Sperello di Serego; Dunkley, Joanna; Dvorkin, Cora; Errard, Josquin; Fabbian, Giulio; Feeney, Stephen; Ferraro, Simone; Filippini, Jeffrey P; Flauger, Raphael; Fuller, George M; Gluscevic, Vera; Green, Daniel; Grin, Daniel; Grohs, Evan; Henning, Jason W; Hill, J Colin; Hlozek, Renee; Holder, Gilbert; Holzapfel, William; Hu, Wayne; Huffenberger, Kevin M; Keskitalo, Reijo; Knox, Lloyd; Kosowsky, Arthur; Kovac, John; Kovetz, Ely D; Kuo, Chao-Lin; Kusaka, Akito; Jeune, Maude Le; Lee, Adrian T; Lilley, Marc; Loverde, Marilena; Madhavacheril, Mathew S; Mantz, Adam; Marsh, David J E; McMahon, Jeffrey; Meerburg, Pieter Daniel; Meyers, Joel; Miller, Amber D; Munoz, Julian B; Nguyen, Ho Nam; Niemack, Michael D; Peloso, Marco; Peloton, Julien; Pogosian, Levon; Pryke, Clement; Raveri, Marco; Reichardt, Christian L; Rocha, Graca; Rotti, Aditya; Schaan, Emmanuel; Schmittfull, Marcel M; Scott, Douglas; Sehgal, Neelima; Shandera, Sarah; Sherwin, Blake D; Smith, Tristan L; Sorbo, Lorenzo; Starkman, Glenn D; Story, Kyle T; van Engelen, Alexander; Vieira, Joaquin D; Watson, Scott; Whitehorn, Nathan; Wu, W L Kimmy

    2016-01-01

    This book lays out the scientific goals to be addressed by the next-generation ground-based cosmic microwave background experiment, CMB-S4, envisioned to consist of dedicated telescopes at the South Pole, the high Chilean Atacama plateau and possibly a northern hemisphere site, all equipped with new superconducting cameras. CMB-S4 will dramatically advance cosmological studies by crossing critical thresholds in the search for the B-mode polarization signature of primordial gravitational waves, in the determination of the number and masses of the neutrinos, in the search for evidence of new light relics, in constraining the nature of dark energy, and in testing general relativity on large scales.

  4. CMB-S4 and the Hemispherical Variance Anomaly

    CERN Document Server

    O'Dwyer, Marcio; Knox, Lloyd; Starkman, Glenn D

    2016-01-01

    Cosmic Microwave Background (CMB) full-sky temperature data show a hemispherical asymmetry in power nearly aligned with the Ecliptic. In real space, this anomaly can be quantified by the temperature variance in the northern and southern Ecliptic hemispheres. In this context, the northern hemisphere displays an anomalously low variance while the southern hemisphere appears unremarkable (consistent with expectations from the best-fitting theory, $\\Lambda$CDM). While this is a well established result in temperature, the low signal-to-noise ratio in current polarization data prevents a similar comparison. This will change with a proposed ground-based CMB experiment, CMB-S4. With that in mind, we generate realizations of polarization maps constrained by the temperature data and predict the distribution of the hemispherical variance in polarization considering two different sky coverage scenarios possible in CMB-S4: full Ecliptic north coverage and just the portion of the North that can be observed from a ground ba...

  5. Violation of Bell inequality based on S4 symmetry

    Science.gov (United States)

    Bolonek-Lasoń, Katarzyna

    2016-08-01

    In two recent papers [Phys. Rev. A 90, 062121 (2014), 10.1103/PhysRevA.90.062121 and Phys. Rev. A, 91, 052110 (2015), 10.1103/PhysRevA.91.052110] an interesting method of analyzing the violation of Bell inequalities has been proposed which is based on the theory of finite group representations. Here we apply this method to more complicated examples of S4 symmetry. We show how the Bell inequality can be related to the symmetries of regular tetrahedron. By choosing the orbits of three-dimensional representations of S4 determined by the geometry of tetrahedron we find that the Bell inequality under consideration is violated in quantum theory. The corresponding nonlocal game is analyzed.

  6. CMB-S4 Science Book, First Edition

    Energy Technology Data Exchange (ETDEWEB)

    Abazajian, Kevork N. [Univ. of California, Irvine, CA (United States); et al.

    2016-10-09

    This book lays out the scientific goals to be addressed by the next-generation ground-based cosmic microwave background experiment, CMB-S4, envisioned to consist of dedicated telescopes at the South Pole, the high Chilean Atacama plateau and possibly a northern hemisphere site, all equipped with new superconducting cameras. CMB-S4 will dramatically advance cosmological studies by crossing critical thresholds in the search for the B-mode polarization signature of primordial gravitational waves, in the determination of the number and masses of the neutrinos, in the search for evidence of new light relics, in constraining the nature of dark energy, and in testing general relativity on large scales.

  7. Efficient Low Voltage Amplification Using Self Starting Voltage Regulator for Storage System

    Directory of Open Access Journals (Sweden)

    Haslinah Binti Mohd Nasir

    2014-10-01

    Full Text Available This paper presents a storage system design based on energy harvesting to achieve batteryless for Wireless Sensor Network (WSN application. The storage system is part of the Wireless Sensor Energy Harvesting to store and amplify the energy harvested from the surroundings. Finding a new sources of renewable energy has becomes a fashionable among researchers nowadays in particular harvesting the energy from the surrounding. However the challenge raised is to boost up the energy that known are very low. Thus the proposed method must be consumes very little power and suitable for ambient environmental sources such as vibration, wind and RF energy and be able to boost up the energy for storage system. The output of the harvested voltage is insufficient for most applications, therefore the system will boost up the input voltage level using DC to DC converter topology to higher dc voltage.The DC to DC converter shall be designed to suit the types of storage required. The output voltage of this DC converter should be sufficient to charge either capacitor or supercapacitor that will be use in this system as the energy storage system. The supercapacitor will provide power to energize any system such as in this case wireless sensor network[1]. In the case of wireless sensor network for example, the node would require the energy during transmitting and receiving data only whereas during standby mode or sleep mode, the amount of energy required would be very small[2]. Therefore the storage system will make use of this standby time or sleep mode of the sensor node to store as much energy as possible. The presented DC to DC converter in this paper has high efficiency upto 85.4% with input voltage between range 300mV to 600mV.

  8. Voltage verification unit

    Science.gov (United States)

    Martin, Edward J.

    2008-01-15

    A voltage verification unit and method for determining the absence of potentially dangerous potentials within a power supply enclosure without Mode 2 work is disclosed. With this device and method, a qualified worker, following a relatively simple protocol that involves a function test (hot, cold, hot) of the voltage verification unit before Lock Out/Tag Out and, and once the Lock Out/Tag Out is completed, testing or "trying" by simply reading a display on the voltage verification unit can be accomplished without exposure of the operator to the interior of the voltage supply enclosure. According to a preferred embodiment, the voltage verification unit includes test leads to allow diagnostics with other meters, without the necessity of accessing potentially dangerous bus bars or the like.

  9. Electrocatalytic cermet sensor

    Science.gov (United States)

    Shoemaker, Erika L.; Vogt, Michael C.

    1998-01-01

    A sensor for O.sub.2 and CO.sub.2 gases. The gas sensor includes a plurality of layers driven by a cyclic voltage to generate a unique plot characteristic of the gas in contact with the sensor. The plurality of layers includes an alumina substrate, a reference electrode source of anions, a lower electrical reference electrode of Pt coupled to the reference source of anions, a solid electrolyte containing tungsten and coupled to the lower reference electrode, a buffer layer for preventing flow of Pt ions into the solid electrolyte and an upper catalytically active Pt electrode coupled to the buffer layer.

  10. Differential-output B-dot and D-dot monitors for current and voltage measurements on a 20-MA, 3-MV pulsed-power accelerator

    Directory of Open Access Journals (Sweden)

    T. C. Wagoner

    2008-10-01

    Full Text Available We have developed a system of differential-output monitors that diagnose current and voltage in the vacuum section of a 20-MA 3-MV pulsed-power accelerator. The system includes 62 gauges: 3 current and 6 voltage monitors that are fielded on each of the accelerator’s 4 vacuum-insulator stacks, 6 current monitors on each of the accelerator’s 4 outer magnetically insulated transmission lines (MITLs, and 2 current monitors on the accelerator’s inner MITL. The inner-MITL monitors are located 6 cm from the axis of the load. Each of the stack and outer-MITL current monitors comprises two separate B-dot sensors, each of which consists of four 3-mm-diameter wire loops wound in series. The two sensors are separately located within adjacent cavities machined out of a single piece of copper. The high electrical conductivity of copper minimizes penetration of magnetic flux into the cavity walls, which minimizes changes in the sensitivity of the sensors on the 100-ns time scale of the accelerator’s power pulse. A model of flux penetration has been developed and is used to correct (to first order the B-dot signals for the penetration that does occur. The two sensors are designed to produce signals with opposite polarities; hence, each current monitor may be regarded as a single detector with differential outputs. Common-mode-noise rejection is achieved by combining these signals in a 50-Ω balun. The signal cables that connect the B-dot monitors to the balun are chosen to provide reasonable bandwidth and acceptable levels of Compton drive in the bremsstrahlung field of the accelerator. A single 50-Ω cable transmits the output signal of each balun to a double-wall screen room, where the signals are attenuated, digitized (0.5-ns/sample, numerically compensated for cable losses, and numerically integrated. By contrast, each inner-MITL current monitor contains only a single B-dot sensor. These monitors are fielded in opposite-polarity pairs. The two

  11. Differential B-dot and D-dot monitors for current and voltage measurements on a 20-MA 3-MV pulsed-power accelerator.

    Energy Technology Data Exchange (ETDEWEB)

    Shoup, Roy Willlam (ITT Industries, Albuquerque, NM); Gilliland, Terrance Leo (Ktech Corporation, Albuquerque, NM); Lee, James R.; Speas, Christopher Shane; Kim, Alexandre A. (High Current Electronic Institute, Russian Academy of Sciences, Tomsk, Russia); Struve, Kenneth William; York, Mathew William; Leifeste, Gordon T.; Rochau, Gregory Alan; Sharpe, Arthur William; Stygar, William A.; Porter, John Larry Jr.; Wagoner, Tim C. (Ktech Corporation, Albuquerque, NM); Reynolds, Paul Gerard (Team Specialty Products Corporation, Albuquerque, NM); Slopek, Jeffrey Scott (Ktech Corporation, Albuquerque, NM); Moore, William B. S.; Dinwoodie, Thomas Albert (Ktech Corporation, Albuquerque, NM); Woodring, R. M. (Ktech Corporation, Albuquerque, NM); Broyles, Robin Scott (Ktech Corporation, Albuquerque, NM); Mills, Jerry Alan; Melville, J. A. (Prodyn Technologies Incorporated, Albuquerque, NM); Dudley, M. E. (Ktech Corporation, Albuquerque, NM); Androlewicz, K. E. (Ktech Corporation, Albuquerque, NM); Mourning, R. W. (Ktech Corporation, Albuquerque, NM); Moore, J. K. (Ktech Corporation, Albuquerque, NM); Serrano, Jason Dimitri (Ktech Corporation, Albuquerque, NM); Ives, H. C. (EG& G, Albuquerque, NM); Johnson, M. F. (Team Specialty Products Corporation, Albuquerque, NM); Peyton, B. P. (Ktech Corporation, Albuquerque, NM); Leeper, Ramon Joe; Savage, Mark Edward; Donovan, Guy Louis; Spielman, R. B. (Ktech Corporation, Albuquerque, NM); Seamen, Johann F.

    2007-12-01

    We have developed a system of differential-output monitors that diagnose current and voltage in the vacuum section of a 20-MA 3-MV pulsed-power accelerator. The system includes 62 gauges: 3 current and 6 voltage monitors that are fielded on each of the accelerator's 4 vacuum-insulator stacks, 6 current monitors on each of the accelerator's 4 outer magnetically insulated transmission lines (MITLs), and 2 current monitors on the accelerator's inner MITL. The inner-MITL monitors are located 6 cm from the axis of the load. Each of the stack and outer-MITL current monitors comprises two separate B-dot sensors, each of which consists of four 3-mm-diameter wire loops wound in series. The two sensors are separately located within adjacent cavities machined out of a single piece of copper. The high electrical conductivity of copper minimizes penetration of magnetic flux into the cavity walls, which minimizes changes in the sensitivity of the sensors on the 100-ns time scale of the accelerator's power pulse. A model of flux penetration has been developed and is used to correct (to first order) the B-dot signals for the penetration that does occur. The two sensors are designed to produce signals with opposite polarities; hence, each current monitor may be regarded as a single detector with differential outputs. Common-mode-noise rejection is achieved by combining these signals in a 50-{Omega} balun. The signal cables that connect the B-dot monitors to the balun are chosen to provide reasonable bandwidth and acceptable levels of Compton drive in the bremsstrahlung field of the accelerator. A single 50-{omega} cable transmits the output signal of each balun to a double-wall screen room, where the signals are attenuated, digitized (0.5-ns/sample), numerically compensated for cable losses, and numerically integrated. By contrast, each inner-MITL current monitor contains only a single B-dot sensor. These monitors are fielded in opposite-polarity pairs. The two

  12. Entanglement entropy and duality in AdS4

    Directory of Open Access Journals (Sweden)

    Ioannis Bakas

    2015-07-01

    Full Text Available Small variations of the entanglement entropy δS and the expectation value of the modular Hamiltonian δE are computed holographically for circular entangling curves in the boundary of AdS4, using gravitational perturbations with general boundary conditions in spherical coordinates. Agreement with the first law of thermodynamics, δS=δE, requires that the line element of the entangling curve remains constant. In this context, we also find a manifestation of electric–magnetic duality for the entanglement entropy and the corresponding modular Hamiltonian, following from the holographic energy–momentum/Cotton tensor duality.

  13. Synthsis of(3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid%(3 S,4 S)-4-氨基-3-羟基-6-甲基庚酸的合成

    Institute of Scientific and Technical Information of China (English)

    金瑛; 张天一; 刘帆

    2015-01-01

    (3S,4S)-4-(Dibenzylamino)-3-hydroxy-6-methyl-heptanoic acid was synthesized from L-Leucine by protection of amino and carboxyl group to give( S)-2-( dibenzylamino)-4-methylbenzyl valerate,which was subjected to nucleophilic substitution with acetontrile and stereoselective reduction with NaBH4 to afford(3S,4S)-4-(dibenzylamino)-3-hydroxy-6-methylheptanenitrile,fol-lowed by oxidation with hydrogen peroxide to give(3S,4S)-4-(dibenzylamino)-3-hydroxy-6-methylheptanoic acid. Finally,depro-tection of benzyl group in presence of Pd(OH)2/C-H2 to achieve(3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid in an overall yield of about 33. 6%.%价廉易得的L-亮氨酸先以苄基同时保护氨基及羧基得( S)-2-(二苄胺基)-4-甲基戊酸苄酯,进而在碱性条件下与乙腈发生亲核取代反应得( S)-4-(二苄胺基)-6-甲基-3-氧代庚腈,再经硼氢化钠选择性还原羰基得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚腈,用双氧水氧化得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚酸,最后在Pd(OH)2/C-H2作用下脱掉苄基得到(3S,4S)-4-氨基-3-羟基-6-甲基庚酸,即(3S,4S)-statine。整个合成路线总产率为33.6%。

  14. SOGI-based capacitor voltage feedback active damping in LCL-filtered grid converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    The capacitor voltage feedback active damping control is an attractive way to suppress LCL-filter resonance especially for the systems where the capacitor voltage is used for grid synchronization, since no extra sensors are added. The derivative is the core of the capacitor voltage feedback active...... derivative is more suited for capacitor voltage feedback active damping control. Experimental results validate the effectiveness of the proposed method....

  15. Pirquitasite, Ag2ZnSnS4

    Directory of Open Access Journals (Sweden)

    Benjamin N. Schumer

    2013-02-01

    Full Text Available Pirquitasite, ideally Ag2ZnSnS4 (disilver zinc tin tetrasulfide, exhibits tetragonal symmetry and is a member of the stannite group that has the general formula A2BCX4, with A = Ag, Cu; B = Zn, Cd, Fe, Cu, Hg; C = Sn, Ge, Sb, As; and X = S, Se. In this study, single-crystal X-ray diffraction data are used to determine the structure of pirquitasite from a twinned crystal from the type locality, the Pirquitas deposit, Jujuy Province, Argentina, with anisotropic displacement parameters for all atoms, and a measured composition of (Ag1.87Cu0.13(Zn0.61Fe0.36Cd0.03SnS4. One Ag atom is located on Wyckoff site Wyckoff 2a (symmetry -4.., the other Ag atom is statistically disordered with minor amounts of Cu and is located on 2c (-4.., the (Zn, Fe, Cd site on 2d (-4.., Sn on 2b (-4.., and S on general site 8g. This is the first determination of the crystal structure of pirquitasite, and our data indicate that the space group of pirquitasite is I-4, rather than I-42m as previously suggested. The structure was refined under consideration of twinning by inversion [twin ratio of the components 0.91 (6:0.09 (6].

  16. Littlest Seesaw model from S4 x U(1)

    CERN Document Server

    King, Stephen F

    2016-01-01

    We show how a minimal (littlest) seesaw model involving two right-handed neutrinos and a very constrained Dirac mass matrix, with one texture zero and two independent Dirac masses, may arise from $S_4\\times U(1)$ symmetry. The resulting CSD3 form of neutrino mass matrix only depends on two real mass parameters plus one undetermined phase. We show how the phase may be fixed to be one of the cube roots of unity by extending the $S_4\\times U(1)$ symmetry to include a product of $Z_3$ factors together with a CP symmetry, which is spontaneously broken leaving a single residual $Z_3$ in the charged lepton sector and a residual $Z_2$ in the neutrino sector, with suppressed higher order corrections. With the phase chosen from the cube roots of unity to be $-2\\pi/3$, the model predicts a normal neutrino mass hierarchy with $m_1=0$, reactor angle $\\theta_{13}=8.7^\\circ$, solar angle $\\theta_{12}=34^\\circ$, atmospheric angle $\\theta_{23}=44^\\circ$, and CP violating oscillation phase $\\delta_{\\rm CP}=-93^\\circ$, dependin...

  17. Littlest Seesaw model from S 4 × U(1)

    Science.gov (United States)

    King, Stephen F.; Luhn, Christoph

    2016-09-01

    We show how a minimal (littlest) seesaw model involving two right-handed neutrinos and a very constrained Dirac mass matrix, with one texture zero and two independent Dirac masses, may arise from S 4 ×U(1) symmetry in a semi-direct supersymmetric model. The resulting CSD3 form of neutrino mass matrix only depends on two real mass parameters plus one undetermined phase. We show how the phase may be fixed to be one of the cube roots of unity by extending the S 4 × U(1) symmetry to include a product of Z 3 factors together with a CP symmetry, which is spontaneously broken leaving a single residual Z 3 in the charged lepton sector and a residual Z 2 in the neutrino sector, with suppressed higher order corrections. With the phase chosen from the cube roots of unity to be -2π /3, the model predicts a normal neutrino mass hierarchy with m 1 = 0, reactor angle θ 13 = 8 .7°, solar angle θ 12 = 34°, atmospheric angle θ 23 = 44°, and CP violating oscillation phase δ CP = -93°, depending on the fit of the model to the neutrino masses.

  18. Interaction of local anesthetics with a peptide encompassing the IV/S4-S5 linker of the Na+ channel.

    Science.gov (United States)

    Fraceto, Leonardo F; Oyama, Sérgio; Nakaie, Clóvis R; Spisni, Alberto; de Paula, Eneida; Pertinhez, Thelma A

    2006-08-20

    The peptide pIV/S4-S5 encompasses the cytoplasmic linker between helices S4-S5 in domain IV of the voltage-gated Na+ channel, residues 1644-1664. The interaction of two local anesthetics (LA), lidocaine and benzocaine, with pIV/S4-S5 has been studied by DOSY, heteronuclear NMR 1H-15N-HSQC spectroscopy and computational methods. DOSY indicates that benzocaine, a neutral ester, exhibits stronger interaction with pIV/S4-S5 than lidocaine, a charged amine-amide. Weighted average chemical shifts, Deltadelta(1H-15N), show that benzocaine affects residues L1653, M1655 and S1656 while lidocaine slightly perturbs residues I1646, L1649 and A1659, L1660, near the N- and C-terminus, respectively. Computational methods confirmed the stability of the benzocaine binding and the existence of two binding sites for lidocaine. Even considering that the approach of studying the peptide in the presence of a co-solvent (TFE/H2O, 30%/70% v/v) has an inherently limited implication, our data strongly support the existence of multiple LA binding sites in the IV/S4-S5 linker, as suggested in the literature. In addition, we consider that LA can bind to the S4-S5 linker with diverse binding modes and strength since this linker is part of the receptor for the "inactivation gate particle". Conditions for devising new functional studies, aiming to better understand Na+ channel functionality as well as the various facets of LA pharmacological activity are proposed in this work.

  19. The solution structure of the S4-S5 linker of the hERG potassium channel.

    Science.gov (United States)

    Gayen, Shovanlal; Li, Qingxin; Kang, CongBao

    2012-02-01

    The human ether-à-go-go related gene (hERG) encodes a protein that forms a voltage-gated potassium channel and plays an important role in the heart by controlling the rapid delayed rectifier K(+) current (I(Kr)). The S4-S5 linker was shown to be important for the gating of the hERG channel. Nuclear magnetic resonance study showed that a peptide derived from the S4-S5 linker had no well-ordered structure in aqueous solution and adopted a 3(10) -helix (E544-Y545-G546) structure in detergent micelles. The existence of an amphipathic helix was confirmed, which may be important for interaction with cell membrane. Close contact between side chains of residues R541 and E544 was observed, which may be important for its regulation of channel gating.

  20. Biased low differential input impedance current receiver/converter device and method for low noise readout from voltage-controlled detectors

    Science.gov (United States)

    Degtiarenko, Pavel V.; Popov, Vladimir E.

    2011-03-22

    A first stage electronic system for receiving charge or current from voltage-controlled sensors or detectors that includes a low input impedance current receiver/converter device (for example, a transimpedance amplifier), which is directly coupled to the sensor output, a source of bias voltage, and the device's power supply (or supplies), which use the biased voltage point as a baseline.

  1. Color regeneration from reflective color sensor using an artificial intelligent technique.

    Science.gov (United States)

    Saracoglu, Ömer Galip; Altural, Hayriye

    2010-01-01

    A low-cost optical sensor based on reflective color sensing is presented. Artificial neural network models are used to improve the color regeneration from the sensor signals. Analog voltages of the sensor are successfully converted to RGB colors. The artificial intelligent models presented in this work enable color regeneration from analog outputs of the color sensor. Besides, inverse modeling supported by an intelligent technique enables the sensor probe for use of a colorimetric sensor that relates color changes to analog voltages.

  2. Inductive Position Sensor

    Science.gov (United States)

    Youngquist, Robert C. (Inventor); Simmons, Stephen M. (Inventor)

    2015-01-01

    An inductive position sensor uses three parallel inductors, each of which has an axial core that is an independent magnetic structure. A first support couples first and second inductors and separate them by a fixed distance. A second support coupled to a third inductor disposed between the first and second inductors. The first support and second support are configured for relative movement as distance changes from the third inductor to each of the first and second inductors. An oscillating current is supplied to the first and second inductors. A device measures a phase component of a source voltage generating the oscillating current and a phase component of voltage induced in the third inductor when the oscillating current is supplied to the first and second inductors such that the phase component of the voltage induced overlaps the phase component of the source voltage.

  3. Creation and electrical properties of p-Cu2ZnSnS4/ n-Si heterojunctions

    Science.gov (United States)

    Yusupov, A.; Adambaev, K.; Turaev, Z. Z.; Aliev, S. R.; Kutlimratov, A.

    2017-01-01

    Anisotype p-Cu2ZnSnS4/ n-Si heterojunctions have been manufactured for the first type by sulfidation of base-metal layers predeposited onto polycrystalline silicon substrates. Current-voltage characteristics of the heterojunctions are analyzed, and the mechanisms of current transfer are discussed. It is established that forward-biased structures are characterized by both tunneling-recombination processes and space-charge limited mobility of carriers. In reversely biased heterojunctions, space-charge limited currents predominate.

  4. KV4.3 expression and gating: S2 and S3 acidic and S4 innermost basic residues.

    Science.gov (United States)

    Skerritt, Matthew R; Campbell, Donald L

    2009-11-01

    Effects of neutralizing individual negatively charged (acidic [E,D]) and innermost positively charged (basic [K,R]) residues in transmembrane segments S2 (D230Q, E240Q), S3 (D263Q) and S4 (K299A/Q, R302A/Q) of the K(V)4.3 putative voltage sensing domain (VSD) were determined. S2 D230Q generated large macroscopic currents, depolarized steady-state activation ("a(4)") and isochronal (1 sec) inactivation ("i") relationships, and significantly accelerated kinetics of deactivation and recovery (from both macroscopic and closed state inactivation [CSI]). D230Q thus stabilized non-inactivated closed states. These effects were attributable to structural perturbations, and indicated D230 is not primarily involved in voltage sensing. Both S2 E240Q and S3 D263Q failed to generate measurable ionic currents, suggesting deletion of negative charges at these putatively more intracellular acidic positions were functionally "lethal" to macroscopic K(V)4.3 function. S4 innermost positive charge deletion mutants K299A/Q and R032A/Q generated functional currents with reduced peak amplitudes. While reduced K299A/Q and R302A/Q currents prevented accurate determination of "a(4)" and estimates of potential electrostatic perturbations, both sets of mutants: (i) depolarized potentials at which currents could be macroscopically detected, consistent with stabilization of closed states (structural perturbations); and (ii) accelerated macroscopic recovery. These results provide further evidence that: (i) basic residues in S4 are involved not only in regulating K(V)4.3 activation and deactivation, but also CSI and recovery; and (ii) suggest putative electrostatic interactions between acidic S2/S3 and basic S4 residues may be different in K(V)4.3 from those proposed to exist in Shaker. Functional implications are discussed.

  5. High Voltage Distribution

    Science.gov (United States)

    Norbeck, Edwin; Miller, Michael; Onel, Yasar

    2010-11-01

    For detector arrays that require 5 to 10 kV at a few microamps each for hundreds of detectors, using hundreds of HV power supplies is unreasonable. Bundles of hundreds of HV cables take up space that should be filled with detectors. A typical HV module can supply 1 ma, enough current for hundreds of detectors. It is better to use a single HV module and distribute the current as needed. We show a circuit that, for each detector, measures the current, cuts off the voltage if the current exceeds a set maximum, and allows the HV to be turned on or off from a control computer. The entire array requires a single HV cable and 2 or 3 control lines. This design provides the same voltage to all of the detectors, the voltage set by the single HV module. Some additional circuitry would allow a computer controlled voltage drop between the HV and each individual detector.

  6. High voltage engineering fundamentals

    CERN Document Server

    Kuffel, E; Hammond, P

    1984-01-01

    Provides a comprehensive treatment of high voltage engineering fundamentals at the introductory and intermediate levels. It covers: techniques used for generation and measurement of high direct, alternating and surge voltages for general application in industrial testing and selected special examples found in basic research; analytical and numerical calculation of electrostatic fields in simple practical insulation system; basic ionisation and decay processes in gases and breakdown mechanisms of gaseous, liquid and solid dielectrics; partial discharges and modern discharge detectors; and over

  7. Compact steep-spectrum sources from the S4 sample

    CERN Document Server

    Saikia, D J; Salter, C J; Thomasson, P; Spencer, R E; Mantovani, F

    2000-01-01

    We present the results of 5-GHz observations with the VLA A-array of a sample of candidate Compact Steep Spectrum sources (CSSs) selected from the S4 survey. We also estimate the symmetry parameters of high-luminosity CSSs selected from different samples of radio sources, and compare these with the larger sources of similar luminosity to understand their evolution and the consistency of the CSSs with the unified scheme for radio galaxies and quasars. The majority of CSSs are likely to be young sources advancing outwards through a dense asymmetric environment. The radio properties of CSSs are found to be consistent with the unified scheme, in which the axes of the quasars are observed close to the line of sight, while radio galaxies are observed close to the plane of the sky.

  8. Neutrino masses and mixing from S4 flavor twisting

    CERN Document Server

    Ishimori, Hajime; Tanimoto, Morimitsu; Watanabe, Atsushi

    2010-01-01

    We discuss a neutrino mass model based on the S4 discrete symmetry where the symmetry breaking is triggered by the boundary conditions of the bulk right-handed neutrino in the fifth spacial dimension. While the symmetry restricts bare mass parameters to flavor-diagonal forms, the viable mixing angles emerge from the wave functions of the Kaluza-Klein modes which carry symmetry breaking effect. The magnitudes of the lepton mixing angles, especially the reactor angle is related to the neutrino mass patterns and the model will be tested in future neutrino experiments, e.g., an early (late) discovery of the reactor angle favors the normal (inverted) hierarchy. The size of extra dimension has a connection to the possible mass spectrum; a small (large) volume corresponds to the normal (inverted) mass hierarchy.

  9. Low-voltage gyrotrons

    Science.gov (United States)

    Glyavin, M. Yu.; Zavolskiy, N. A.; Sedov, A. S.; Nusinovich, G. S.

    2013-03-01

    For a long time, the gyrotrons were primarily developed for electron cyclotron heating and current drive of plasmas in controlled fusion reactors where a multi-megawatt, quasi-continuous millimeter-wave power is required. In addition to this important application, there are other applications (and their number increases with time) which do not require a very high power level, but such issues as the ability to operate at low voltages and have compact devices are very important. For example, gyrotrons are of interest for a dynamic nuclear polarization, which improves the sensitivity of the nuclear magnetic resonance spectroscopy. In this paper, some issues important for operation of gyrotrons driven by low-voltage electron beams are analyzed. An emphasis is made on the efficiency of low-voltage gyrotron operation at the fundamental and higher cyclotron harmonics. These efficiencies calculated with the account for ohmic losses were, first, determined in the framework of the generalized gyrotron theory based on the cold-cavity approximation. Then, more accurate, self-consistent calculations for the fundamental and second harmonic low-voltage sub-THz gyrotron designs were carried out. Results of these calculations are presented and discussed. It is shown that operation of the fundamental and second harmonic gyrotrons with noticeable efficiencies is possible even at voltages as low as 5-10 kV. Even the third harmonic gyrotrons can operate at voltages about 15 kV, albeit with rather low efficiency (1%-2% in the submillimeter wavelength region).

  10. CMB-S4 and the hemispherical variance anomaly

    Science.gov (United States)

    O'Dwyer, Márcio; Copi, Craig J.; Knox, Lloyd; Starkman, Glenn D.

    2017-09-01

    Cosmic microwave background (CMB) full-sky temperature data show a hemispherical asymmetry in power nearly aligned with the Ecliptic. In real space, this anomaly can be quantified by the temperature variance in the Northern and Southern Ecliptic hemispheres, with the Northern hemisphere displaying an anomalously low variance while the Southern hemisphere appears unremarkable [consistent with expectations from the best-fitting theory, Lambda Cold Dark Matter (ΛCDM)]. While this is a well-established result in temperature, the low signal-to-noise ratio in current polarization data prevents a similar comparison. This will change with a proposed ground-based CMB experiment, CMB-S4. With that in mind, we generate realizations of polarization maps constrained by the temperature data and predict the distribution of the hemispherical variance in polarization considering two different sky coverage scenarios possible in CMB-S4: full Ecliptic north coverage and just the portion of the North that can be observed from a ground-based telescope at the high Chilean Atacama plateau. We find that even in the set of realizations constrained by the temperature data, the low Northern hemisphere variance observed in temperature is not expected in polarization. Therefore, observing an anomalously low variance in polarization would make the hypothesis that the temperature anomaly is simply a statistical fluke more unlikely and thus increase the motivation for physical explanations. We show, within ΛCDM, how variance measurements in both sky coverage scenarios are related. We find that the variance makes for a good statistic in cases where the sky coverage is limited, however, full northern coverage is still preferable.

  11. Rain Drop Charge Sensor

    Science.gov (United States)

    S, Sreekanth T.

    begin{center} Large Large Rain Drop Charge Sensor Sreekanth T S*, Suby Symon*, G. Mohan Kumar (1) , S. Murali Das (2) *Atmospheric Sciences Division, Centre for Earth Science Studies, Thiruvananthapuram 695011 (1) D-330, Swathi Nagar, West Fort, Thiruvananthapuram 695023 (2) Kavyam, Manacaud, Thiruvananthapuram 695009 begin{center} ABSTRACT To study the inter-relations with precipitation electricity and precipitation microphysical parameters a rain drop charge sensor was designed and developed at CESS Electronics & Instrumentation Laboratory. Simultaneous measurement of electric charge and fall speed of rain drops could be done using this charge sensor. A cylindrical metal tube (sensor tube) of 30 cm length is placed inside another thick metal cover opened at top and bottom for electromagnetic shielding. Mouth of the sensor tube is exposed and bottom part is covered with metal net in the shielding cover. The instrument is designed in such a way that rain drops can pass only through unhindered inside the sensor tube. When electrically charged rain drops pass through the sensor tube, it is charged to the same magnitude of drop charge but with opposite polarity. The sensor tube is electrically connected the inverted input of a current to voltage converter operational amplifier using op-amp AD549. Since the sensor is electrically connected to the virtual ground of the op-amp, the charge flows to the ground and the generated current is converted to amplified voltage. This output voltage is recorded using a high frequency (1kHz) voltage recorder. From the recorded pulse, charge magnitude, polarity and fall speed of rain drop are calculated. From the fall speed drop diameter also can be calculated. The prototype is now under test running at CESS campus. As the magnitude of charge in rain drops is an indication of accumulated charge in clouds in lightning, this instrument has potential application in the field of risk and disaster management. By knowing the charge

  12. A fault-tolerant voltage measurement method for series connected battery packs

    Science.gov (United States)

    Xia, Bing; Mi, Chris

    2016-03-01

    This paper proposes a fault-tolerant voltage measurement method for battery management systems. Instead of measuring the voltage of individual cells, the proposed method measures the voltage sum of multiple battery cells without additional voltage sensors. A matrix interpretation is developed to demonstrate the viability of the proposed sensor topology to distinguish between sensor faults and cell faults. A methodology is introduced to isolate sensor and cell faults by locating abnormal signals. A measurement electronic circuit is proposed to implement the design concept. Simulation and experiment results support the mathematical analysis and validate the feasibility and robustness of the proposed method. In addition, the measurement problem is generalized and the condition for valid sensor topology is discovered. The tuning of design parameters are analyzed based on fault detection reliability and noise levels.

  13. Study on the Stereoselective Synthesis of Carbapenem Sidechain (2S,4S)-4-Acetylsulphanyl-2-[(S)-1-phenylethylcarbamoyl]-pyrrolidine-1-carboxylic Acid 4-Nitrobenzyl Ester

    Institute of Scientific and Technical Information of China (English)

    Qian LIU; Gang FANG; Li Ping WU; Jian Mei CUI; Xiao Tian LIANG; Song WU

    2004-01-01

    A stereoselective and economic synthesis of the carbapenem sidechain (2S, 4S)-4-ace-tylsulphanyl-2-[ (S)1-phenylethyl-carbamoyl] pyrrolidine-l-carboxylic acid 4-nitrobenzyl ester was developed. Due to the effect of spatial hindrance, only the (2S,4S) diastereomer 3 was obtained by coupling 1 and the inexpensive racemic 2 catalyzed by EEDQ.

  14. NiCo2S4 nanowires array as an efficient bifunctional electrocatalyst for full water splitting with superior activity

    Science.gov (United States)

    Liu, Danni; Lu, Qun; Luo, Yonglan; Sun, Xuping; Asiri, Abdullah M.

    2015-09-01

    The present communication reports the topotactic conversion of NiCo2O4 nanowires array on carbon cloth (NiCo2O4 NA/CC) into NiCo2S4 NA/CC, which is used as an efficient bifunctional electrocatalyst for water splitting with good durability and superior activity in 1.0 M KOH. This NiCo2S4 NA/CC electrode produces 100 mA cm-2 at an overpotential of 305 mV for hydrogen evolution and 100 mA cm-2 at an overpotential of 340 mV for oxygen evolution. To afford a 10 mA cm-2 water-splitting current, the alkaline water electrolyzer made from NiCo2S4 NA/CC needs a cell voltage of 1.68 V, which is 300 mV less than that for NiCo2O4 NA/CC, and has good stability.The present communication reports the topotactic conversion of NiCo2O4 nanowires array on carbon cloth (NiCo2O4 NA/CC) into NiCo2S4 NA/CC, which is used as an efficient bifunctional electrocatalyst for water splitting with good durability and superior activity in 1.0 M KOH. This NiCo2S4 NA/CC electrode produces 100 mA cm-2 at an overpotential of 305 mV for hydrogen evolution and 100 mA cm-2 at an overpotential of 340 mV for oxygen evolution. To afford a 10 mA cm-2 water-splitting current, the alkaline water electrolyzer made from NiCo2S4 NA/CC needs a cell voltage of 1.68 V, which is 300 mV less than that for NiCo2O4 NA/CC, and has good stability. Electronic supplementary information (ESI) available: Experimental section and ESI Figures. See DOI: 10.1039/c5nr04064g

  15. Device for monitoring cell voltage

    Science.gov (United States)

    Doepke, Matthias [Garbsen, DE; Eisermann, Henning [Edermissen, DE

    2012-08-21

    A device for monitoring a rechargeable battery having a number of electrically connected cells includes at least one current interruption switch for interrupting current flowing through at least one associated cell and a plurality of monitoring units for detecting cell voltage. Each monitoring unit is associated with a single cell and includes a reference voltage unit for producing a defined reference threshold voltage and a voltage comparison unit for comparing the reference threshold voltage with a partial cell voltage of the associated cell. The reference voltage unit is electrically supplied from the cell voltage of the associated cell. The voltage comparison unit is coupled to the at least one current interruption switch for interrupting the current of at least the current flowing through the associated cell, with a defined minimum difference between the reference threshold voltage and the partial cell voltage.

  16. High voltage pulse generator

    Science.gov (United States)

    Fasching, George E.

    1977-03-08

    An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

  17. Structural determinants for the action of grayanotoxin in D1 S4-S5 and D4 S4-S5 intracellular linkers of sodium channel alpha-subunits.

    Science.gov (United States)

    Maejima, Hiroshi; Kinoshita, Eiji; Yuki, Tsunetsugu; Yakehiro, Masuhide; Seyama, Issei; Yamaoka, Kaoru

    2002-07-12

    We located a novel binding site for grayanotoxin on the cytoplasmic linkers of voltage-dependent cardiac (rH1) or skeletal-muscle (mu 1) Na(+) channel isoforms (segments S4-S5 in domains D1 and D4), using the alanine scanning substitution method. GTX-modification of Na(+) channels, transiently expressed in HEK 293 cells, was evaluated under whole-cell voltage clamp, from the ratio of maximum chord conductance for modified and unmodified Na(+) channels. In mu 1, mutations K237A, L243A, S246A, K248A, K249A, L250A, S251A, or T1463A, caused a moderate, but statistically significant decrease in this ratio. On making corresponding mutations in rH1, only L244A dramatically reduced the ratio. Because in mu 1, the serine at position 251 is the only heterologous residue with respect to rH1 (Ala-252), we made a double mutant L243A&S251A to match the sequence of mu 1 and rH1 in S4-S5 linkers of both domains. This double mutation resulted in a significant decrease in the ratio, to the same extent as L244A substitution in rH1 did, indicating that the site at Leu-244 in rH1 or at Leu-243 in mu 1 is a novel one, exhibiting a synergistic effect of grayanotoxin.

  18. Two atomic constraints unambiguously position the S4 segment relative to S1 and S2 segments in the closed state of Shaker K channel.

    Science.gov (United States)

    Campos, Fabiana V; Chanda, Baron; Roux, Benoît; Bezanilla, Francisco

    2007-05-01

    It is now well established that the voltage-sensing S4 segment in voltage-dependent ion channels undergoes a conformational change in response to varying membrane potential. However, the magnitude of the movement of S4 relative to the membrane and the rest of the protein remains controversial. Here, by using histidine scanning mutagenesis in the Shaker K channel, we identified mutants I241H (S1 segment) and I287H (S2 segment) that generate inward currents at hyperpolarized potentials, suggesting that these residues are part of a hydrophobic plug that separates the water-accessible crevices. Additional experiments with substituted cysteine residues showed that, at hyperpolarized potentials, both I241C and I287C can spontaneously form disulphide and metal bridges with R362C, the position of the first charge-carrying residue in S4. These results constrain unambiguously the closed-state positions of the S4 segment with respect to the S1 and S2 segments, which are known to undergo little or no movement during gating. To satisfy these constraints, the S4 segment must undergo an axial rotation of approximately 180 degrees and a transmembrane (vertical) movement of approximately 6.5 A at the level of R362 in going from the open to the closed state of the channel, moving the gating charge across a focused electric field.

  19. Stability of Charged Global AdS$_4$ Spacetimes

    CERN Document Server

    Arias, Raúl; Serantes, Alexandre

    2016-01-01

    We study linear and nonlinear stability of asymptotically AdS$_4$ solutions in Einstein-Maxwell-scalar theory. After summarizing the set of static solutions we first examine thermodynamical stability in the grand canonical ensemble and the phase transitions that occur among them. In the second part of the paper we focus on nonlinear stability in the microcanonical ensemble by evolving radial perturbations numerically. We find hints of an instability corner for vanishingly small perturbations of the same kind as the ones present in the uncharged case. Collapses are avoided, instead, if the charge and mass of the perturbations come to close the line of solitons. Finally we examine the soliton solutions. The linear spectrum of normal modes is not resonant and instability turns on at extrema of the mass curve. Linear stability extends to nonlinear stability up to some threshold for the amplitude of the perturbation. Beyond that, the soliton is destroyed and collapses to a hairy black hole. The relative width of t...

  20. S4: A Spatial-Spectral model for Speckle Suppression

    CERN Document Server

    Fergus, Rob; Oppenheimer, Rebecca; Brenner, Douglas; Pueyo, Laurent

    2014-01-01

    High dynamic-range imagers aim to block out or null light from a very bright primary star to make it possible to detect and measure far fainter companions; in real systems a small fraction of the primary light is scattered, diffracted, and unocculted. We introduce S4, a flexible data-driven model for the unocculted (and highly speckled) light in the P1640 spectroscopic coronograph. The model uses Principal Components Analysis (PCA) to capture the spatial structure and wavelength dependence of the speckles but not the signal produced by any companion. Consequently, the residual typically includes the companion signal. The companion can thus be found by filtering this error signal with a fixed companion model. The approach is sensitive to companions that are of order a percent of the brightness of the speckles, or up to $10^{-7}$ times the brightness of the primary star. This outperforms existing methods by a factor of 2-3 and is close to the shot-noise physical limit.

  1. S4: A spatial-spectral model for speckle suppression

    Energy Technology Data Exchange (ETDEWEB)

    Fergus, Rob [Department of Computer Science, New York University, New York, NY 10003 (United States); Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003 (United States); Oppenheimer, Rebecca; Brenner, Douglas [Department of Astrophysics, American Museum of Natural History, New York, NY 10024-5192 (United States); Pueyo, Laurent, E-mail: fergus@cs.nyu.edu [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

    2014-10-20

    High dynamic range imagers aim to block or eliminate light from a very bright primary star in order to make it possible to detect and measure far fainter companions; in real systems, a small fraction of the primary light is scattered, diffracted, and unocculted. We introduce S4, a flexible data-driven model for the unocculted (and highly speckled) light in the P1640 spectroscopic coronagraph. The model uses principal components analysis (PCA) to capture the spatial structure and wavelength dependence of the speckles, but not the signal produced by any companion. Consequently, the residual typically includes the companion signal. The companion can thus be found by filtering this error signal with a fixed companion model. The approach is sensitive to companions that are of the order of a percent of the brightness of the speckles, or up to 10{sup –7} times the brightness of the primary star. This outperforms existing methods by a factor of two to three and is close to the shot-noise physical limit.

  2. The stellar mass distribution of S$^{4}$G disk galaxies

    CERN Document Server

    Díaz-García, Simón; Laurikainen, Eija

    2016-01-01

    We use 3.6 $\\mu$m imaging from the S$^{4}$G survey to characterize the typical stellar density profiles ($\\Sigma_{\\ast}$) and bars as a function of fundamental galaxy parameters (e.g. the total stellar mass $M_{\\ast}$), providing observational constraints for galaxy simulation models to be compared with. We rescale galaxy images to a common frame determined by the size in physical units, by their disk scalelength, or by their bar size and orientation. We stack the resized images to obtain statistically representative average stellar disks and bars. For a given $M_{\\ast}$ bin ($\\ge 10^{9}M_{\\odot}$), we find a significant difference in the stellar density profiles of barred and non-barred systems that gives evidence for bar-induced secular evolution of disk galaxies: (i) disks in barred galaxies show larger scalelengths and fainter extrapolated central surface brightnesses, (ii) the mean surface brightness profiles of barred and non-barred galaxies intersect each other slightly beyond the mean bar length, most...

  3. Investigation of magnetic properties on spin-ordering effects of FeGa2S4 and FeIn2S4

    Science.gov (United States)

    Myoung, Bo Ra; Lim, Jung Tae; Kim, Chul Sung

    2017-09-01

    We have studied crystal and magnetic properties of chalcogenides FeGa2S4 and FeIn2S4 with X-ray diffractometer (XRD), magnetic property measurement system (MPMS), magnetometer, physical property measurement system (PPMS), and Mössbauer spectrometer. The crystal structure has 2-dimension triangular lattice structure with P-3m1 of FeGa2S4, while FeIn2S4 has inverse spinel with space group Fd3m. The AC magnetic susceptibility measurements show that FeGa2S4 is an insulating spin glass material, exhibiting geometrical frustration, unlike in the antiferromagnetic [AFM] metallic spin glass FeIn2S4. From hysteresis (M-H) curves at 4.2 K, FeGa2S4 has spin-flop behavior with an angle of 120° of triangle, as against linear slope of FeIn2S4 due to anti-parallel spin. The gap energy by splitting of 5T2g, Δ1 and electric quadrupole splitting ΔEQ of FeIn2S4 are much higher than that of FeGa2S4 at 4.2 K because FeGa2S4 is geometrically frustrated magnet having degenerate ground state at low temperature.

  4. System for improving measurement accuracy of transducer by measuring transducer temperature and resistance change using thermoelectric voltages

    Science.gov (United States)

    Anderson, Karl F. (Inventor); Parker, Allen R., Jr. (Inventor)

    1993-01-01

    A constant current loop measuring system measures a property including the temperature of a sensor responsive to an external condition being measured. The measuring system includes thermocouple conductors connected to the sensor, sensing first and second induced voltages responsive to the external condition. In addition, the measuring system includes a current generator and reverser generating a constant current, and supplying the constant current to the thermocouple conductors in forward and reverse directions generating first and second measured voltages, and a determining unit receiving the first and second measured voltages from the current generator and reverser, and determining the temperature of the sensor responsive to the first and second measured voltages.

  5. Low voltage integrated optics electro-optical modulator applied to optical voltage transformer based on WLI technique

    Science.gov (United States)

    Santos, J. C.; Rubini, J.; Silva, L. P. C.; Caetano, R. E.

    2015-09-01

    The use of two electro-optical modulators linked in series, one for sensing and one for recovering signals, was formerly presented by some of the authors as a solution for interrogation of optical fiber sensor systems based on WLI method. A key feature required from such systems is that half-wave voltage (Vπ) of recovering modulator must be as small as possible. Aiming at meeting this requirement, in this paper it is presented the use of an unbalanced Michelson Interferometer implemented using an integrated optics component as recover interferometer in an optical voltage transformer intended for high voltage measurements.

  6. Voltage Regulators for Photovoltaic Systems

    Science.gov (United States)

    Delombard, R.

    1986-01-01

    Two simple circuits developed to provide voltage regulation for highvoltage (i.e., is greater than 75 volts) and low-voltage (i.e., is less than 36 volts) photovoltaic/battery power systems. Use of these circuits results in voltage regulator small, low-cost, and reliable, with very low power dissipation. Simple oscillator circuit controls photovoltaic-array current to regulate system voltage and control battery charging. Circuit senses battery (and system) voltage and adjusts array current to keep battery voltage from exceeding maximum voltage.

  7. Voltage-sensitive rhodol with enhanced two-photon brightness.

    Science.gov (United States)

    Kulkarni, Rishikesh U; Kramer, Daniel J; Pourmandi, Narges; Karbasi, Kaveh; Bateup, Helen S; Miller, Evan W

    2017-03-14

    We have designed, synthesized, and applied a rhodol-based chromophore to a molecular wire-based platform for voltage sensing to achieve fast, sensitive, and bright voltage sensing using two-photon (2P) illumination. Rhodol VoltageFluor-5 (RVF5) is a voltage-sensitive dye with improved 2P cross-section for use in thick tissue or brain samples. RVF5 features a dichlororhodol core with pyrrolidyl substitution at the nitrogen center. In mammalian cells under one-photon (1P) illumination, RVF5 demonstrates high voltage sensitivity (28% ΔF/F per 100 mV) and improved photostability relative to first-generation voltage sensors. This photostability enables multisite optical recordings from neurons lacking tuberous sclerosis complex 1, Tsc1, in a mouse model of genetic epilepsy. Using RVF5, we show that Tsc1 KO neurons exhibit increased activity relative to wild-type neurons and additionally show that the proportion of active neurons in the network increases with the loss of Tsc1. The high photostability and voltage sensitivity of RVF5 is recapitulated under 2P illumination. Finally, the ability to chemically tune the 2P absorption profile through the use of rhodol scaffolds affords the unique opportunity to image neuronal voltage changes in acutely prepared mouse brain slices using 2P illumination. Stimulation of the mouse hippocampus evoked spiking activity that was readily discerned with bath-applied RVF5, demonstrating the utility of RVF5 and molecular wire-based voltage sensors with 2P-optimized fluorophores for imaging voltage in intact brain tissue.

  8. High voltage dc-dc converter with dynamic voltage regulation and decoupling during load-generated arcs

    Science.gov (United States)

    Shimer, Daniel W.; Lange, Arnold C.

    1995-01-01

    A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.

  9. Studying Voltage Transformer Ferroresonance

    Directory of Open Access Journals (Sweden)

    Hamid Radmanesh

    2012-09-01

    Full Text Available This study studies the effect of Circuit Breaker Shunt Resistance (CBSR, Metal Oxide Vaistor (MOV and Neutral earth Resistance (NR on the control of ferroresonance in the voltage transformer. It is expected that NR can controlled ferroresonance better than MOV and CBSR. Study has been done on a one phase voltage transformer rated 100 VA, 275 kV. The simulation results reveal that considering the CBSR and MOV exhibits a great mitigating effect on ferroresonance overvoltages, but these resistances cannot control these phenomena for all range of parameters. By applying NR to the system structure, ferroresonance has been controlled and its amplitude has been damped for all parameters values.

  10. Modular sensor network node

    Science.gov (United States)

    Davis, Jesse Harper Zehring; Stark, Jr., Douglas Paul; Kershaw, Christopher Patrick; Kyker, Ronald Dean

    2008-06-10

    A distributed wireless sensor network node is disclosed. The wireless sensor network node includes a plurality of sensor modules coupled to a system bus and configured to sense a parameter. The parameter may be an object, an event or any other parameter. The node collects data representative of the parameter. The node also includes a communication module coupled to the system bus and configured to allow the node to communicate with other nodes. The node also includes a processing module coupled to the system bus and adapted to receive the data from the sensor module and operable to analyze the data. The node also includes a power module connected to the system bus and operable to generate a regulated voltage.

  11. Non-Invasive Electro-Magnetic Field Sensor.

    Science.gov (United States)

    1986-01-01

    69 30 Fiber optic sensor’s response to a pulsed electric field . 74 31 Fiber optic electric field sensor’s response to an oscil- latory field...first test type involved a pulsed electric field . The applied voltage pulse was negative with a peak voltage of approxi- mately -24,000 volts and a

  12. VOLTAGE REGULATORS ASYNCHRONOUS GENERATORS

    Directory of Open Access Journals (Sweden)

    Grigorash O. V.

    2015-06-01

    Full Text Available A promising is currently the use of asynchronous generators with capacitive excitation as a source of electricity in stand-alone power systems. Drive asynchronous generators may exercise as a thermal engine and wind wheel wind power plant or turbines of small hydropower plants. The article discusses the structural and schematics of voltage stabilizers and frequency of asynchronous generators with improved operational and technical specifications. Technical novelty of design solutions of the magnetic system and stabilizers asynchronous generator of electricity parameters confirmed by the patents for the invention of the Russian Federation. The proposed technical solution voltage stabilizer asynchronous generators, can reduce the weight of the block capacitors excitation and reactive power compensation, as well as to simplify the control system power circuit which has less power electronic devices. For wind power plants it is an important issue not only to stabilize the voltage of the generator, but also the frequency of the current. Recommend functionality stabilizer schemes parameters of electric power made for direct frequency converters with artificial and natural switching power electronic devices. It is also proposed as part of stabilization systems use single-phase voltage, three-phase transformers with rotating magnetic field, reduce the level of electromagnetic interference generated by power electronic devices for switching, enhance the efficiency and reliability of the stabilizer.

  13. Geomagnetism and Induced Voltage

    Science.gov (United States)

    Abdul-Razzaq, W.; Biller, R. D.

    2010-01-01

    Introductory physics laboratories have seen an influx of "conceptual integrated science" over time in their classrooms with elements of other sciences such as chemistry, biology, Earth science, and astronomy. We describe a laboratory to introduce this development, as it attracts attention to the voltage induced in the human brain as it…

  14. High-voltage picoamperemeter

    Energy Technology Data Exchange (ETDEWEB)

    Bugl, Andrea; Ball, Markus; Boehmer, Michael; Doerheim, Sverre; Hoenle, Andreas; Konorov, Igor [Technische Universitaet Muenchen, Garching (Germany); Ketzer, Bernhard [Technische Universitaet Muenchen, Garching (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany)

    2014-07-01

    Current measurements in the nano- and picoampere region on high voltage are an important tool to understand charge transfer processes in micropattern gas detectors like the Gas Electron Multiplier (GEM). They are currently used to e.g. optimize the field configuration in a multi-GEM stack to be used in the ALICE TPC after the upgrade of the experiment during the 2nd long shutdown of the LHC. Devices which allow measurements down to 1pA at high voltage up to 6 kV have been developed at TU Muenchen. They are based on analog current measurements via the voltage drop over a switchable shunt. A microcontroller collects 128 digital ADC values and calculates their mean and standard deviation. This information is sent with a wireless transmitting unit to a computer and stored in a root file. A nearly unlimited number of devices can be operated simultaneously and read out by a single receiver. The results can also be displayed on a LCD directly at the device. Battery operation and the wireless readout are important to protect the user from any contact to high voltage. The principle of the device is explained, and systematic studies of their properties are shown.

  15. Surface functionalized Cu2Zn1- x Cd x SnS4 quinternary alloyed nanostructure for DNA sensing

    Science.gov (United States)

    Ibraheam, A. S.; Al-Douri, Y.; Voon, C. H.; Foo, K. L.; Azizah, N.; Gopinath, S. C. B.; Ameri, M.; Ibrahim, Sattar S.

    2017-03-01

    A sensing plate of extended Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures, fabricated on an oxidized silicon substrate by the sol-gel method, is reported in this paper. The fabricated device was characterized and analyzed via field emission-scanning electron microscopy, X-ray diffraction (XRD), and photoluminescence (PL). The XRD peaks shifted towards the lower angle side alongside increasing concentration of cadmium. The average diameter of the Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures falls between 21.55 and 43.12 nm, while the shift of the PL bandgap was from 1.81 eV ( x = 0) to 1.72 eV ( x = 1). The resulting Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures components were functionalized with oligonucleotides probe DNA molecules and interacted with the target, exhibiting good sensing capabilities due to its large surface-to-volume ratio. The fabrication, immobilization, and hybridization processes were analyzed via representative current-voltage ( I- V) plots. Its electrical profile shows that the device is capable to distinguish biomolecules. Its high performance was evident from the linear relationship between the probe DNA from cervical cancer and the target DNA, showing its applicability for medical applications.

  16. Structural refinement of the hERG1 pore and voltage-sensing domains with ROSETTA-membrane and molecular dynamics simulations.

    Science.gov (United States)

    Subbotina, Julia; Yarov-Yarovoy, Vladimir; Lees-Miller, James; Durdagi, Serdar; Guo, Jiqing; Duff, Henry J; Noskov, Sergei Yu

    2010-11-01

    The hERG1 gene (Kv11.1) encodes a voltage-gated potassium channel. Mutations in this gene lead to one form of the Long QT Syndrome (LQTS) in humans. Promiscuous binding of drugs to hERG1 is known to alter the structure/function of the channel leading to an acquired form of the LQTS. Expectably, creation and validation of reliable 3D model of the channel have been a key target in molecular cardiology and pharmacology for the last decade. Although many models were built, they all were limited to pore domain. In this work, a full model of the hERG1 channel is developed which includes all transmembrane segments. We tested a template-driven de-novo design with ROSETTA-membrane modeling using side-chain placements optimized by subsequent molecular dynamics (MD) simulations. Although backbone templates for the homology modeled parts of the pore and voltage sensors were based on the available structures of KvAP, Kv1.2 and Kv1.2-Kv2.1 chimera channels, the missing parts are modeled de-novo. The impact of several alignments on the structure of the S4 helix in the voltage-sensing domain was also tested. Herein, final models are evaluated for consistency to the reported structural elements discovered mainly on the basis of mutagenesis and electrophysiology. These structural elements include salt bridges and close contacts in the voltage-sensor domain; and the topology of the extracellular S5-pore linker compared with that established by toxin foot-printing and nuclear magnetic resonance studies. Implications of the refined hERG1 model to binding of blockers and channels activators (potent new ligands for channel activations) are discussed.

  17. Non-contact current and voltage sensing method using a clamshell housing and a ferrite cylinder

    Science.gov (United States)

    Carpenter, Gary D.; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C.; Schappert, Michael

    2016-04-26

    A method of measurement using a detachable current and voltage sensor provides an isolated and convenient technique for to measuring current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing that contains the current and voltage sensors, which may be a ferrite cylinder with a hall effect sensor disposed in a gap along the circumference to measure current, or alternative a winding provided through the cylinder along its axis and a capacitive plate or wire disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

  18. Optically monitoring voltage in neurons by photo-induced electron transfer through molecular wires.

    Science.gov (United States)

    Miller, Evan W; Lin, John Y; Frady, E Paxon; Steinbach, Paul A; Kristan, William B; Tsien, Roger Y

    2012-02-07

    Fluorescence imaging is an attractive method for monitoring neuronal activity. A key challenge for optically monitoring voltage is development of sensors that can give large and fast responses to changes in transmembrane potential. We now present fluorescent sensors that detect voltage changes in neurons by modulation of photo-induced electron transfer (PeT) from an electron donor through a synthetic molecular wire to a fluorophore. These dyes give bigger responses to voltage than electrochromic dyes, yet have much faster kinetics and much less added capacitance than existing sensors based on hydrophobic anions or voltage-sensitive ion channels. These features enable single-trial detection of synaptic and action potentials in cultured hippocampal neurons and intact leech ganglia. Voltage-dependent PeT should be amenable to much further optimization, but the existing probes are already valuable indicators of neuronal activity.

  19. Sensor Technology Baseline Study for Enabling Condition Based Maintenance Plus in Army Ground Vehicles

    Science.gov (United States)

    2012-03-01

    and mechanisms are identified. Based on this analysis, baselines sensor technologies are determined to prognosticate these types failure causes early...Current/voltage sensor measured at sensor terminals; Fluid level sensor Excessive slippage and clutch chatter Internal transmission failure ... TYPE Final 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Sensor Technology Baseline Study for Enabling Condition Based Maintenance Plus in

  20. Scalar and Spinor Field Actions on Fuzzy $S^4$: fuzzy $CP^3$ as a $S^2_F$ bundle over $S^4_F$

    CERN Document Server

    Medina, Julieta; O'Connor, Denjoe; Dolan, Brian P

    2012-01-01

    We present a manifestly Spin(5) invariant construction of squashed fuzzy $CP^3$ as a fuzzy $S^2$ bundle over fuzzy $S^4$. We develop the necessary projectors and exhibit the squashing in terms of the radii of the $S^2$ and $S^4$. Our analysis allows us give both scalar and spinor fuzzy action functionals whose low lying modes are truncated versions of those of a commutative $S^4$.

  1. Two distinct voltage-sensing domains control voltage sensitivity and kinetics of current activation in CaV1.1 calcium channels.

    Science.gov (United States)

    Tuluc, Petronel; Benedetti, Bruno; Coste de Bagneaux, Pierre; Grabner, Manfred; Flucher, Bernhard E

    2016-06-01

    Alternative splicing of the skeletal muscle CaV1.1 voltage-gated calcium channel gives rise to two channel variants with very different gating properties. The currents of both channels activate slowly; however, insertion of exon 29 in the adult splice variant CaV1.1a causes an ∼30-mV right shift in the voltage dependence of activation. Existing evidence suggests that the S3-S4 linker in repeat IV (containing exon 29) regulates voltage sensitivity in this voltage-sensing domain (VSD) by modulating interactions between the adjacent transmembrane segments IVS3 and IVS4. However, activation kinetics are thought to be determined by corresponding structures in repeat I. Here, we use patch-clamp analysis of dysgenic (CaV1.1 null) myotubes reconstituted with CaV1.1 mutants and chimeras to identify the specific roles of these regions in regulating channel gating properties. Using site-directed mutagenesis, we demonstrate that the structure and/or hydrophobicity of the IVS3-S4 linker is critical for regulating voltage sensitivity in the IV VSD, but by itself cannot modulate voltage sensitivity in the I VSD. Swapping sequence domains between the I and the IV VSDs reveals that IVS4 plus the IVS3-S4 linker is sufficient to confer CaV1.1a-like voltage dependence to the I VSD and that the IS3-S4 linker plus IS4 is sufficient to transfer CaV1.1e-like voltage dependence to the IV VSD. Any mismatch of transmembrane helices S3 and S4 from the I and IV VSDs causes a right shift of voltage sensitivity, indicating that regulation of voltage sensitivity by the IVS3-S4 linker requires specific interaction of IVS4 with its corresponding IVS3 segment. In contrast, slow current kinetics are perturbed by any heterologous sequences inserted into the I VSD and cannot be transferred by moving VSD I sequences to VSD IV. Thus, CaV1.1 calcium channels are organized in a modular manner, and control of voltage sensitivity and activation kinetics is accomplished by specific molecular mechanisms

  2. VFT PHASE VOLTAGE MEASUREMENT IN THREE-PHASE ENCLOSED GIS

    Institute of Scientific and Technical Information of China (English)

    邹建华; 岳子丁; 李洋

    2002-01-01

    The measuring of VFT phase voltage in three-phase enclosed GIS is more complex and difficult than in single-phase ones. There are 3 capacitive sensors in the measuring system, the outputs of which are with a linear relation to the three phase voltages. This linear relation is presented with a factorial matrix. Because each capacitive sensor is coupled with the electric field of three phases (A, B, and C), the electric coupling coefficients are introduced. In order to determine the matrix of electric coupling coefficients, the numerical calculation method can be used. From the discussion on two types of three-phase enclosed GIS bus, i.e. standard arrangement and biased arrangement, the dominant electric coupling coefficients are named, which can be simply and approximately calculated by an analytic expression. Finally, as an example, the waveforms of VFT phase voltage generated on a three-phase enclosed GIS bus model are displayed. When a capacitive sensor is located at the 'shortest point' of phase A (or B, or C), the VFT phase voltage VA (or VB, or VC) can almost be measured by that capacitive sensor alone.

  3. Optogenetic Monitoring of Synaptic Activity with Genetically Encoded Voltage Indicators

    Science.gov (United States)

    Nakajima, Ryuichi; Jung, Arong; Yoon, Bong-June; Baker, Bradley J.

    2016-01-01

    The age of genetically encoded voltage indicators (GEVIs) has matured to the point that changes in membrane potential can now be observed optically in vivo. Improving the signal size and speed of these voltage sensors has been the primary driving forces during this maturation process. As a result, there is a wide range of probes using different voltage detecting mechanisms and fluorescent reporters. As the use of these probes transitions from optically reporting membrane potential in single, cultured cells to imaging populations of cells in slice and/or in vivo, a new challenge emerges—optically resolving the different types of neuronal activity. While improvements in speed and signal size are still needed, optimizing the voltage range and the subcellular expression (i.e., soma only) of the probe are becoming more important. In this review, we will examine the ability of recently developed probes to report synaptic activity in slice and in vivo. The voltage-sensing fluorescent protein (VSFP) family of voltage sensors, ArcLight, ASAP-1, and the rhodopsin family of probes are all good at reporting changes in membrane potential, but all have difficulty distinguishing subthreshold depolarizations from action potentials and detecting neuronal inhibition when imaging populations of cells. Finally, we will offer a few possible ways to improve the optical resolution of the various types of neuronal activities. PMID:27547183

  4. Deployment of low-voltage regulator considering existing voltage control in medium-voltage distribution systems

    Directory of Open Access Journals (Sweden)

    Hiroshi Kikusato

    2016-01-01

    Full Text Available Many photovoltaic (PV systems have been installed in distribution systems. This installation complicates the maintenance of all voltages within the appropriate range in all low-voltage distribution systems (LVDSs because the trends in voltage fluctuation differ in each LVDS. The installation of a low-voltage regulator (LVR that can accordingly control the voltage in each LVDS has been studied as a solution to this problem. Voltage control in a medium-voltage distribution system must be considered to study the deployment of LVRs. In this study, we installed LVRs in the LVDSs in which the existing voltage-control scheme cannot prevent voltage deviation and performed a numerical simulation by using a distribution system model with PV to evaluate the deployment of the LVRs.

  5. Omega currents in voltage-gated ion channels: what can we learn from uncovering the voltage-sensing mechanism using MD simulations?

    Science.gov (United States)

    Tarek, Mounir; Delemotte, Lucie

    2013-12-17

    Ion channels conduct charged species through otherwise impermeable biological membranes. Their activity supports a number of physiological processes, and genetic mutations can disrupt their function dramatically. Among these channels, voltage gated cation channels (VGCCs) are ubiquitous transmembrane proteins involved in electrical signaling. In addition to their selectivity for ions, their function requires membrane-polarization-dependent gating. Triggered by changes in the transmembrane voltage, the activation and deactivation of VGCCs proceed through a sensing mechanism that prompts motion of conserved positively charged (basic) residues within the S4 helix of a four-helix bundle, the voltage sensor domain (VSD). Decades of experimental investigations, using electrophysiology, molecular biology, pharmacology, and spectroscopy, have revealed details about the function of VGCCs. However, in 2005, the resolution of the crystal structure of the activated state of one member of the mammalian voltage gated potassium (Kv) channels family (the Kv1.2) enabled researchers to make significant progress in understanding the structure-function relationship in these proteins on a molecular level. In this Account, we review the use of a complementary technique, molecular dynamics (MD) simulations, that has offered new insights on this timely issue. Starting from the "open-activated state" crystal structure, we have carried out large-scale all atom MD simulations of the Kv1.2 channel embedded in its lipidic environment and submitted to a hyperpolarizing (negative) transmembrane potential. We then used steered MD simulations to complete the full transition to the resting-closed state. Using these procedures, we have followed the operation of the VSDs and uncovered three intermediate states between their activated and deactivated conformations. Each conformational state is characterized by its network of salt bridges and by the occupation of the gating charge transfer center by a

  6. Analyzing of Dynamic Voltage Restorer in Series Compensation Voltage

    Directory of Open Access Journals (Sweden)

    Naser Parhizgar

    2012-02-01

    Full Text Available The Dynamic Voltage Restorer (DVR is a series-connected compensator to generate a controllable voltage to against the short-term voltage disturbances. The technique of DVR is an effective and cost competitive approach to improve voltage quality at the load side. This study presents a single-phase and threephase DVR system with reduced switch-count topology to protect the sensitive load against abnormal voltage conditions. Most basic function, the DVR configuration consist of a two level Voltage Source Converter (VSC, a dc energy storage device, a coupling transformer Connected in shunt with the ac system This study presents the application of Dynamic Voltage Restorer (DVR on power distribution systems for mitigation of voltage sag at critical loads. DVR is one of the compensating types of custom power devices. The DVR, which is based on forced-commutated Voltage Source Converter (VSC has been proved suitable for the task of compensating voltage sags/swells. Simulation results are presented to illustrate and understand the performances of DVR in supporting load voltages under voltage sags/swells conditions.

  7. High Voltage Charge Pump

    KAUST Repository

    Emira, Ahmed A.

    2014-10-09

    Various embodiments of a high voltage charge pump are described. One embodiment is a charge pump circuit that comprises a plurality of switching stages each including a clock input, a clock input inverse, a clock output, and a clock output inverse. The circuit further comprises a plurality of pumping capacitors, wherein one or more pumping capacitors are coupled to a corresponding switching stage. The circuit also comprises a maximum selection circuit coupled to a last switching stage among the plurality of switching stages, the maximum selection circuit configured to filter noise on the output clock and the output clock inverse of the last switching stage, the maximum selection circuit further configured to generate a DC output voltage based on the output clock and the output clock inverse of the last switching stage.

  8. DFT study of optoelectronic and magnetic properties of iron-containing diamond-like materials Ag2FeSiS4, Li2FeSnS4, and Li2FeGeS4

    Science.gov (United States)

    Azam, Sikander; Khan, Saleem Ayaz; Goumri-Said, Souraya

    2017-10-01

    Ag2FeSiS4, Li2FeSnS4, and Li2FeGeS4 have been studied by first-principles calculations within density functional theory (DFT) added to the Coulomb energy (U Hubbard term) to treat the strong correlation of Fe 3d electrons. All three materials have shown that their conduction band minimum (CBM) and valence band maximum (VBM) were situated at Γ point, indicating a direct band gap of 1.99 and 2.26 eV, 2.24 eV for Ag2FeSiS4, Li2FeSnS4, and Li2FeGeS4 respectively. The lower part of the valence band was dominated by S-s orbitals while the mid part were contributed mostly by Sn/Ge-s and Ag-d states. Hence, the VBM and CBM were mainly due to Fe-d states. The bonding characterization have shown a strong covalent bonding between the Fe-S, Ge-S, Sn-S, Ag-S and Si-S atoms. The imaginary part of the dielectric constant have revealed that the first optical critical point energy occurred at 1.2 eV for Ag2FeSiS4, and at 2.0 eV for Li2FeSnS4, and Li2FeGeS4 compounds leading them to absorb less of visible spectrum. The existence of iron in the composition of these compounds have induced magnetic properties that we explored by the calculation of the magnetic moment and spin-densities maps.

  9. Increased voltage photovoltaic cell

    Science.gov (United States)

    Ross, B.; Bickler, D. B.; Gallagher, B. D. (Inventor)

    1985-01-01

    A photovoltaic cell, such as a solar cell, is provided which has a higher output voltage than prior cells. The improved cell includes a substrate of doped silicon, a first layer of silicon disposed on the substrate and having opposite doping, and a second layer of silicon carbide disposed on the first layer. The silicon carbide preferably has the same type of doping as the first layer.

  10. High Voltage Seismic Generator

    Science.gov (United States)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes

  11. Voltage-induced reduction of graphene oxide

    Science.gov (United States)

    Faucett, Austin C.

    Graphene Oxide (GO) is being widely researched as a precursor for the mass production of graphene, and as a versatile material in its own right for flexible electronics, chemical sensors, and energy harvesting applications. Reduction of GO, an electrically insulating material, into reduced graphene oxide (rGO) restores electrical conductivity via removal of oxygen-containing functional groups. Here, a reduction method using an applied electrical bias, known as voltage-induced reduction, is explored. Voltage-induced reduction can be performed under ambient conditions and avoids the use of hazardous chemicals or high temperatures common with standard methods, but little is known about the reduction mechanisms and the quality of rGO produced with this method. This work performs extensive structural and electrical characterization of voltage-reduced GO (V-rGO) and shows that it is competitive with standard methods. Beyond its potential use as a facile and eco-friendly processing approach, V-rGO reduction also offers record high-resolution patterning capabilities. In this work, the spatial resolution limits of voltage-induced reduction, performed using a conductive atomic force microscope probe, are explored. It is shown that arbitrary V-rGO conductive features can be patterned into insulating GO with nanoscale resolution. The localization of voltage-induced reduction to length scales < 10 nm allows studies of reduction reaction kinetics, using electrical current obtained in-situ, with statistical robustness. Methods for patterning V-rGO nanoribbons are then developed. After presenting sub-10nm patterning of V-rGO nanoribbons in GO single sheets and films, the performance of V-rGO nanoribbon field effect transistors (FETs) are demonstrated. Preliminary measurements show an increase in electrical current on/off ratios as compared to large-area rGO FETs, indicating transport gap modulation that is possibly due to quantum confinement effects.

  12. Detailed Study of Amplitude Nonlinearity in Piezoresistive Force Sensors

    OpenAIRE

    Pablo Gonzalez De Santos; Elena Garcia; Luis Emmi; Leonel Paredes-Madrid

    2011-01-01

    This article upgrades the RC linear model presented for piezoresistive force sensors. Amplitude nonlinearity is found in sensor conductance, and a characteristic equation is formulated for modeling its response under DC-driving voltages below 1 V. The feasibility of such equation is tested on four FlexiForce model A201-100 piezoresistive sensors by varying the sourcing voltage and the applied forces. Since the characteristic equation proves to be valid, a method is presented for obtaining a s...

  13. Computational Chemistry of Modified [MFe3S4] and [M2Fe2S4] Clusters: Assessment of Trends in Electronic Structure and Properties

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta; Ooi, Bee Lean; Christensen, Hans Erik Mølager

    2008-01-01

    The aim of this work is to understand the molecular evolution of iron−sulfur clusters in terms of electronic structure and function. Metal-substituted models of biological [Fe4S4] clusters in oxidation states [MxFe4−xS4]3+/2+/1+ have been studied by density functional theory (M = Cr, Mn, Fe, Co, ...

  14. Computational Chemistry of Modified [MFe3S4] and [M2Fe2S4] Clusters: Assessment of Trends in Electronic Structure and Properties

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta; Ooi, Bee Lean; Christensen, Hans Erik Mølager

    2008-01-01

    The aim of this work is to understand the molecular evolution of iron−sulfur clusters in terms of electronic structure and function. Metal-substituted models of biological [Fe4S4] clusters in oxidation states [MxFe4−xS4]3+/2+/1+ have been studied by density functional theory (M = Cr, Mn, Fe, Co, ...

  15. Mitigation of Voltage Sags in CIGRE Low Voltage Distribution Network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar;

    2013-01-01

    problems in the distribution system. The voltage problems dealt with in this paper are to show how to mitigate voltage sags in the CIGRE Low Voltage (LV) test network and networks like this. The voltage sags, for the tested cases in the CIGRE LV test network are mainly due to three phase faults....... The compensation of voltage sags in the different parts of CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0....

  16. Voltage Controlled Dynamic Demand Response

    DEFF Research Database (Denmark)

    Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    . An adaptive dynamic model has been developed to determine composite voltage dependency of an aggregated load on feeder level. Following the demand dispatch or control signal, optimum voltage setting at the LV substation is determined based on the voltage dependency of the load. Furthermore, a new technique...

  17. Charge-pump voltage converter

    Science.gov (United States)

    Brainard, John P.; Christenson, Todd R.

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  18. Transient voltage sharing in series-coupled high voltage switches

    Directory of Open Access Journals (Sweden)

    Editorial Office

    1992-07-01

    Full Text Available For switching voltages in excess of the maximum blocking voltage of a switching element (for example, thyristor, MOSFET or bipolar transistor such elements are often coupled in series - and additional circuitry has to be provided to ensure equal voltage sharing. Between each such series element and system ground there is a certain parasitic capacitance that may draw a significant current during high-speed voltage transients. The "open" switch is modelled as a ladder network. Analy­sis reveals an exponential progression in the distribution of the applied voltage across the elements. Overstressing thus oc­curs in some of the elements at levels of the total voltage that are significantly below the design value. This difficulty is overcome by grading the voltage sharing circuitry, coupled in parallel with each element, in a prescribed manner, as set out here.

  19. Compositional dependence of charge carrier transport in kesterite Cu2ZnSnS4 solar cells

    Science.gov (United States)

    Just, Justus; Nichterwitz, Melanie; Lützenkirchen-Hecht, Dirk; Frahm, Ronald; Unold, Thomas

    2016-12-01

    Cu2ZnSnS4 solar cells deposited by thermal co-evaporation have been characterized structurally and electronically to determine the dependence of the electronic properties on the elemental composition of the kesterite phase, which can significantly deviate from the total sample composition. To this end, the kesterite phase content and composition were determined by a combination of X-ray fluorescence and X-ray absorption measurements. The electronic properties, such as carrier density and minority carrier diffusion length, were determined by electron beam induced current measurements and capacitance-voltage profiling. The charge-carrier transport properties are found to strongly depend on the Cu/(Sn+Zn) ratio of the kesterite phase. For the Cu-poor sample, a minority carrier diffusion length of 270 nm and a total collection length of approx. 500 nm are deduced, indicating that current collection should not be an issue in thin devices.

  20. Recommendation of Sensors for Vehicle Transmission Diagnostics

    Science.gov (United States)

    2012-05-01

    module. This could degrade the operation of the solenoid to the point that there is a failure or the clutch plates could stick. The viscosity of...Voltage sensor measured at sensor terminals; Fluid level sensor Excessive slippage and Clutch chatter Internal transmission failure ; Faulty torque...ADDRESS. 1. REPORT DATE (DD-MM-YYYY) May 2012 2. REPORT TYPE 3. DATES COVERED (From - To) October 2010 to September 2011 4. TITLE AND SUBTITLE

  1. Voltage balancing strategies for serial connection of microbial fuel cells

    Science.gov (United States)

    Khaled, Firas; Ondel, Olivier; Allard, Bruno; Buret, François

    2015-07-01

    The microbial fuel cell (MFC) converts electrochemically organic matter into electricity by means of metabolisms of bacteria. The MFC power output is limited by low voltage and low current characteristics in the range of microwatts or milliwatts per litre. In order to produce a sufficient voltage level (>1.5 V) and sufficient power to supply real applications such as autonomous sensors, it is necessary to either scale-up one single unit or to connect multiple units together. Many topologies of connection are possible as the serial association to improve the output voltage, or the parallel connection to improve the output current or the series/parallel connection to step-up both voltage and current. The association of MFCs in series is a solution to increase the voltage to an acceptable value and to mutualize the unit's output power. The serial association of a large number of MFCs presents several issues. The first one is the hydraulic coupling among MFCs when they share the same substrate. The second one is the dispersion between generators that lead to a non-optimal stack efficiency because the maximum power point (MPP) operation of all MFCs is not permitted. Voltage balancing is a solution to compensate non-uniformities towards MPP. This paper presents solutions to improve the efficiency of a stack of serially connected MFCs through a voltage-balancing circuit. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2014)", edited by Adel Razek

  2. No-Voltage Meter

    Science.gov (United States)

    1976-02-01

    VW- IKft, 1/4 H4 -Wv- IK!1, I/4W INTERNAL VOLTAGE NOTE ALL TRANSISTORS ARE 2N43A OR EQUIVALENT GERMANIUM ALLOY PNP AA ALKALINE BATTERY...D-,, regardless of polarity. This signal is then full-wave rectified by the diode-connected Germanium transistor bridge, T,, T-,, T3, and T4... Transistor T5 acts as a second current limiter. Resistor R2 was selected to give 90 f# of full-scale meter deflection with an input signal of 115 volts

  3. Paroxysmal extreme pain disorder mutations within the D3/S4-S5 linker of Nav1.7 cause moderate destabilization of fast inactivation.

    Science.gov (United States)

    Jarecki, Brian W; Sheets, Patrick L; Jackson, James O; Cummins, Theodore R

    2008-09-01

    Single-point missense mutations in the peripheral neuronal voltage-gated sodium channel Nav1.7 are implicated in the painful inherited neuropathy paroxysmal extreme pain disorder (PEPD). The Nav1.7 PEPD mutations are located in regions of the channel suggested to play important roles in fast inactivation. PEPD mutations in the putative inactivation gate have been reported to significantly impair fast inactivation, resulting in pronounced persistent currents. However, PEPD mutations in the S4-S5 linker of domain 3 (D3/S4-S5) had not been characterized and the roles of specific residues in this linker in channel gating are unclear. We functionally characterized two of the D3/S4-S5 PEPD mutations (V1298F and V1299F) and compared their effects on gating to an adjacent non-PEPD mutation (V1300F) and the I1461T PEPD mutation, located in the putative inactivation gate. The primary effect of the V1298F and V1299F mutations is to shift the voltage dependence of fast inactivation by approximately 20 mV in the depolarizing direction. We observed a similar effect with the PEPD mutation I1461T. Interestingly, while all three PEPD mutations increased persistent currents, the relative amplitudes (approximately 6% of peak) were much smaller than previously reported for the I1461T mutation. In contrast, the main effect of the V1300F mutation was a depolarizing shift in the voltage dependence of activation. These data demonstrate that (1) mutations within D3/S4-S5 affect inactivation of Nav1.7 in a residue-specific manner and (2) disruption of the fast-inactivated state by PEPD mutations can be more moderate than previously indicated, which has important implications for the pathophysiology of PEPD.

  4. Benchmarking of Voltage Sag Generators

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang

    2012-01-01

    The increased penetration of renewable energy systems, like photovoltaic and wind power systems, rises the concern about the power quality and stability of the utility grid. Some regulations for Low Voltage Ride-Through (LVRT) for medium voltage or high voltage applications, are coming into force...... to guide these grid-connected distributed power generation systems. In order to verify the response of such systems for voltage disturbance, mainly for evaluation of voltage sags/dips, a Voltage Sag Generator (VSG) is needed. This paper evaluates such sag test devices according to IEC 61000 in order...... to provide cheaper solutions to test against voltage sags. Simulation and experimental results demonstrate that the shunt impedance based VSG solution is the easiest and cheapest one for laboratory test applications. The back-to-back fully controlled converter based VSG is the most flexible solution...

  5. An easily fabricated high performance ionic polymer based sensor network

    Science.gov (United States)

    Zhu, Zicai; Wang, Yanjie; Hu, Xiaopin; Sun, Xiaofei; Chang, Longfei; Lu, Pin

    2016-08-01

    Ionic polymer materials can generate an electrical potential from ion migration under an external force. For traditional ionic polymer metal composite sensors, the output voltage is very small (a few millivolts), and the fabrication process is complex and time-consuming. This letter presents an ionic polymer based network of pressure sensors which is easily and quickly constructed, and which can generate high voltage. A 3 × 3 sensor array was prepared by casting Nafion solution directly over copper wires. Under applied pressure, two different levels of voltage response were observed among the nine nodes in the array. For the group producing the higher level, peak voltages reached as high as 25 mV. Computational stress analysis revealed the physical origin of the different responses. High voltages resulting from the stress concentration and asymmetric structure can be further utilized to modify subsequent designs to improve the performance of similar sensors.

  6. Coordinated Voltage Control of Distributed PV Inverters for Voltage Regulation in Low Voltage Distribution Networks

    DEFF Research Database (Denmark)

    Nainar, Karthikeyan; Pokhrel, Basanta Raj; Pillai, Jayakrishnan Radhakrishna

    2017-01-01

    This paper reviews and analyzes the existing voltage control methods of distributed solar PV inverters to improve the voltage regulation and thereby the hosting capacity of a low-voltage distribution network. A novel coordinated voltage control method is proposed based on voltage sensitivity...... analysis, which is simple for computation and requires moderate automation and communication infrastructure. The proposed method is suitable for a hierarchical control structure where a supervisory controller has the provision to adapt the settings of local PV inverter controllers for overall system...

  7. Heat-pump performance: voltage dip/sag, under-voltage and over-voltage

    Directory of Open Access Journals (Sweden)

    William J.B. Heffernan

    2014-12-01

    Full Text Available Reverse cycle air-source heat-pumps are an increasingly significant load in New Zealand and in many other countries. This has raised concern over the impact wide-spread use of heat-pumps may have on the grid. The characteristics of the loads connected to the power system are changing because of heat-pumps. Their performance during under-voltage events such as voltage dips has the potential to compound the event and possibly cause voltage collapse. In this study, results from testing six heat-pumps are presented to assess their performance at various voltages and hence their impact on voltage stability.

  8. EXPERIMENTAL ANALYSIS OF THERMAL FIELD DISTRIBUTION WITHIN THE HIGH VOLTAGE COIL OF X-RAY DETECTOR WITH FLUORESCENT FIBER-OPTIC TEMPERATURE SENSOR%用荧光光纤温度传感器测试X射线探伤机高压包热场分布

    Institute of Scientific and Technical Information of China (English)

    胡红利; 张晓鹏; 徐通模; 于敏

    2001-01-01

    Thermal field distribution within the high voltage coil of type XGQ3005 X-ray detector is measured wity a multi-channel radiation fluorescent fiber-optic temperabure sensor made in our laboratory.The measured results are analyzed and discussed,which give a good reference to the reliable design and the safe use of type XGQ3005 X-ray detector.%采用一种自制的荧光辐射型多路光纤温度传感器,对XGQ3005型充气变频X射线探伤机的高压包(高压变压器绕组)中热场分布进行了测量,给出了测量结果,并进行了分析和讨论;为充气变频X射线探伤机的可靠性设计和安全使用提供了有力的依据。

  9. Review on the Traction System Sensor Technology of a Rail Transit Train.

    Science.gov (United States)

    Feng, Jianghua; Xu, Junfeng; Liao, Wu; Liu, Yong

    2017-06-11

    The development of high-speed intelligent rail transit has increased the number of sensors applied on trains. These play an important role in train state control and monitoring. These sensors generally work in a severe environment, so the key problem for sensor data acquisition is to ensure data accuracy and reliability. In this paper, we follow the sequence of sensor signal flow, present sensor signal sensing technology, sensor data acquisition, and processing technology, as well as sensor fault diagnosis technology based on the voltage, current, speed, and temperature sensors which are commonly used in train traction systems. Finally, intelligent sensors and future research directions of rail transit train sensors are discussed.

  10. Voltage Swells Improvement in Low Voltage Network Using Dynamic Voltage Restorer

    Directory of Open Access Journals (Sweden)

    R. Omar

    2011-01-01

    Full Text Available Problem statement: Voltage disturbances are the most common power quality problem due to the increased use of a large numbers of sophisticated electronic equipment in industrial distribution system. The voltage disturbances such as voltage sags, swells, harmonics, unbalance and flickers. High quality in the power supply is needed, since failures due to such disturbances usually have a high impact on production cost. There are many different solutions to compensate voltage disturbances but the use of a DVR is considered to be the most cost effective method. The objective of this study is to propose a new topology of a DVR in order to mitigate voltage swells using a powerful power custom device namely the Dynamic Voltage Restorer (DVR. Approach: New configuration of a DVR with an improvement of a controller based on direct-quadrature-zero method has been introduced to compensate voltage swells in the network. Results: The effectiveness of the DVR with its controller were verify using Matlab/Simulinks SimPower Toolbox and then implemented using 5KVA DVR experimental setup. Simulations and experimental results demonstrate the effective dynamic performance of the proposed configuration. Conclusion: The implimentation of the proposed DVR validate the capabilities in mitigating of voltage swells effectiveness.During voltage swells, the DVR injects an appropriate voltage to maintain the load voltage at its nominal value.

  11. The S4-S5 linker of KCNQ1 channels forms a structural scaffold with the S6 segment controlling gate closure.

    Science.gov (United States)

    Labro, Alain J; Boulet, Inge R; Choveau, Frank S; Mayeur, Evy; Bruyns, Tine; Loussouarn, Gildas; Raes, Adam L; Snyders, Dirk J

    2011-01-07

    In vivo, KCNQ1 α-subunits associate with the β-subunit KCNE1 to generate the slowly activating cardiac potassium current (I(Ks)). Structurally, they share their topology with other Kv channels and consist out of six transmembrane helices (S1-S6) with the S1-S4 segments forming the voltage-sensing domain (VSD). The opening or closure of the intracellular channel gate, which localizes at the bottom of the S6 segment, is directly controlled by the movement of the VSD via an electromechanical coupling. In other Kv channels, this electromechanical coupling is realized by an interaction between the S4-S5 linker (S4S5(L)) and the C-terminal end of S6 (S6(T)). Previously we reported that substitutions for Leu(353) in S6(T) resulted in channels that failed to close completely. Closure could be incomplete because Leu(353) itself is the pore-occluding residue of the channel gate or because of a distorted electromechanical coupling. To resolve this and to address the role of S4S5(L) in KCNQ1 channel gating, we performed an alanine/tryptophan substitution scan of S4S5(L). The residues with a "high impact" on channel gating (when mutated) clustered on one side of the S4S5(L) α-helix. Hence, this side of S4S5(L) most likely contributes to the electromechanical coupling and finds its residue counterparts in S6(T). Accordingly, substitutions for Val(254) resulted in channels that were partially constitutively open and the ability to close completely was rescued by combination with substitutions for Leu(353) in S6(T). Double mutant cycle analysis supported this cross-talk indicating that both residues come in close contact and stabilize the closed state of the channel.

  12. MFTF sensor verification computer program

    Energy Technology Data Exchange (ETDEWEB)

    Chow, H.K.

    1984-11-09

    The design, requirements document and implementation of the MFE Sensor Verification System were accomplished by the Measurement Engineering Section (MES), a group which provides instrumentation for the MFTF magnet diagnostics. The sensors, installed on and around the magnets and solenoids, housed in a vacuum chamber, will supply information about the temperature, strain, pressure, liquid helium level and magnet voltage to the facility operator for evaluation. As the sensors are installed, records must be maintained as to their initial resistance values. Also, as the work progresses, monthly checks will be made to insure continued sensor health. Finally, after the MFTF-B demonstration, yearly checks will be performed as well as checks of sensors as problem develops. The software to acquire and store the data was written by Harry Chow, Computations Department. The acquired data will be transferred to the MFE data base computer system.

  13. Stabilizing Superacid Anions: The New [H(S4 O13 )2 ](3-) Anion in the Crystal Structure of Li3 [H(S4 O13 )2 ].

    Science.gov (United States)

    Schindler, Lisa Verena; Becker, Anna; Wickleder, Mathias Siegfried

    2016-12-05

    The unique hydrogenium-bis-tetrasulfate anion [H(S4 O13 )2 ](3-) in the crystal structure of Li3 [H(S4 O13 )2 ] (monoclinic, P21 /n (No. 14), Z=2, a=552.46(4) pm, b=939.70(6) pm, c=1876.6(1) pm, β=97.492(3)°, V=965.9(1)⋅10(6)  pm(3) ) is the longest protonated polysulfate chain ever observed. Very strong symmetrical hydrogen bonds are a bold feature of the crystal structure. The protonation of a very weak base such as [S4 O13 ](2-) and accordingly the stabilization of the first base of the superacid H2 S4 O13 is a significant success towards the still elusive polysulfuric acids.

  14. NExt(S4)中 Bull 逻辑再探%Bull’s Logics in NExt(S4) Revisited*

    Institute of Scientific and Technical Information of China (English)

    马明辉

    2013-01-01

      本文重新考察 Bull 在1964给出的一个结论:以纯句法方式定义的一些扩张S4的正规模态逻辑具有有穷模型性质。本文修订 Bull 的代数证明。对于新定义的 S4的 Bull 公式,证明通过它们在 S4基础上生成的正规模态逻辑都具有有穷模型性质。这是关于模态逻辑的有穷模型性质的句法结论。本文还证明,相对于所有克里普克框架类而言,并非所有 S4的 Bull 公式都具有一阶对应句子。%We revisit a result given by Robert Bull in [5] that certain logics in NExt(S4) de-fined by a pure syntax have finite model property and fix Bull’s algebraic proof. We show that every logic in NExt(S4) generated by our new Bull formulas for S4 have finite model property. This is a syntactical result about finite model property of modal logics. We also show that not all Bull formulas for S4 have first-order correspondent with respect the class of all Kripke frames.

  15. Design of output voltage waveform on magnetic encoder

    Energy Technology Data Exchange (ETDEWEB)

    Shi Yu E-mail: shiyu_aaa@163.com; Zhang Huaiwu; Jiang Xiangdong; Wen Qiye; Han Baoshan

    2004-11-01

    A novel design model based on slant multi-phase filter (SMPF) theory is presented. By the theory nth harmonic voltage (n=2nd, 3rd and 4th...(V)) can be reduced easily. Magnetic encoder with sinusoidal output voltage waveform has been developed and sinusoidal output waveform can be easily improved. The minimum of distortion factor was observed when the difference of slant phase is 2{pi}3. This result agrees with SMPF theory value {phi}=4.904 deg. (p=0.8 mm, l=3 mm, {delta}{theta}=2{pi}3]. This result can be widely used in magnetoresistive sensor fields.

  16. Electric Voltage Control as an Implementation of Neural Network Applications

    Directory of Open Access Journals (Sweden)

    A. A. Al-Rababah

    2008-01-01

    Full Text Available Present study was proposed the monitoring of mathematical model of electric voltage source with using neural network for application in control systems as sensor and command signal. The monitoring system, consist of toroidal choke or transformer with high saturated ferromagnetic cores. The input information we receive from current periodic curves. The current was distributed into Fourier or walsh series. The combination of these harmonics and their amplitude values determine monitoring voltage value directly. For increase of this system precision, the mathematical model was constructed on basis of partial differential quasi-stationary electromagnetic field equations and ordi-nary differential electromagnetic circuit equations combination.

  17. Ambient Sensors

    NARCIS (Netherlands)

    Börner, Dirk; Specht, Marcus

    2014-01-01

    This software sketches comprise two custom-built ambient sensors, i.e. a noise and a movement sensor. Both sensors measure an ambient value and process the values to a color gradient (green > yellow > red). The sensors were built using the Processing 1.5.1 development environment. Available under th

  18. Ambient Sensors

    NARCIS (Netherlands)

    Börner, Dirk; Specht, Marcus

    2014-01-01

    This software sketches comprise two custom-built ambient sensors, i.e. a noise and a movement sensor. Both sensors measure an ambient value and process the values to a color gradient (green > yellow > red). The sensors were built using the Processing 1.5.1 development environment. Available under

  19. NOx Sensor Development

    Energy Technology Data Exchange (ETDEWEB)

    Woo, L Y; Glass, R S

    2010-11-01

    NO{sub x} compounds, specifically NO and NO{sub 2}, are pollutants and potent greenhouse gases. Compact and inexpensive NO{sub x} sensors are necessary in the next generation of diesel (CIDI) automobiles to meet government emission requirements and enable the more rapid introduction of more efficient, higher fuel economy CIDI vehicles. Because the need for a NO{sub x} sensor is recent and the performance requirements are extremely challenging, most are still in the development phase. Currently, there is only one type of NO{sub x} sensor that is sold commercially, and it seems unlikely to meet more stringent future emission requirements. Automotive exhaust sensor development has focused on solid-state electrochemical technology, which has proven to be robust for in-situ operation in harsh, high-temperature environments (e.g., the oxygen stoichiometric sensor). Solid-state sensors typically rely on yttria-stabilized zirconia (YSZ) as the oxygen-ion conducting electrolyte and then target different types of metal or metal-oxide electrodes to optimize the response. Electrochemical sensors can be operated in different modes, including amperometric (a current is measured) and potentiometric (a voltage is measured), both of which employ direct current (dc) measurements. Amperometric operation is costly due to the electronics necessary to measure the small sensor signal (nanoampere current at ppm NO{sub x} levels), and cannot be easily improved to meet the future technical performance requirements. Potentiometric operation has not demonstrated enough promise in meeting long-term stability requirements, where the voltage signal drift is thought to be due to aging effects associated with electrically driven changes, both morphological and compositional, in the sensor. Our approach involves impedancemetric operation, which uses alternating current (ac) measurements at a specified frequency. The approach is described in detail in previous reports and several publications

  20. 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.

  1. A probe station for testing silicon sensors

    CERN Multimedia

    Caraban Gonzalez, Noemi

    2017-01-01

    A probe station for testing silicon sensors. The probe station is located inside a dark box that can keep away light during the measurement. The set-up is located in the DSF (Department Silicon Facility). The golden plate is the "chuck" where the sensor is usually placed on. With the help of "manipulators", thin needles can be precisely positioned that can contact the sensor surface. Using these needles and the golden chuck, a high voltage can be applied to the sensor to test its behaviour under high voltage. We will use the silicon sensors that we test here for building prototypes of a highly granular sandwich calorimeter, the CMS HGC (Highly granular Calorimeter) upgrade for High-Luminosity LHC.

  2. A probe station for testing silicon sensors

    CERN Multimedia

    Ulysse, Fichet

    2017-01-01

    A probe station for testing silicon sensors. The probe station is located inside a dark box that can keep away light during the measurement. The set-up is located in the DSF (Department Silicon Facility). The golden plate is the "chuck" where the sensor is usually placed on. With the help of "manipulators", thin needles can be precisely positioned that can contact the sensor surface. Using these needles and the golden chuck, a high voltage can be applied to the sensor to test its behaviour under high voltage. We will use the silicon sensors that we test here for building prototypes of a highly granular sandwich calorimeter, the CMS HGC (Highly granular Calorimeter) upgrade for High-Luminosity LHC.

  3. SDS-assisted hydrothermal synthesis of porous CdIn2S4 microspheres

    Science.gov (United States)

    Bai, X. F.; Li, J. S.; Wu, W.

    2017-02-01

    The porous CdIn2S4 microspheres were synthesized via a sodium dodecyl sulfate (SDS)-assisted hydrothermal technology. The as-prepared CdIn2S4 products were characterized by X-ray diffraction, field emission scanning electron microscopy and UV-Vis diffusive reflectance spectroscopy. The results showed that hydrothermal time and the surfactant addition had great effect on the structure, morphology and optical property of CdIn2S4 products.

  4. Voltage-gated proton channel is expressed on phagosomes.

    Science.gov (United States)

    Okochi, Yoshifumi; Sasaki, Mari; Iwasaki, Hirohide; Okamura, Yasushi

    2009-05-01

    Voltage-gated proton channel has been suggested to help NADPH oxidase activity during respiratory burst of phagocytes through its activities of compensating charge imbalance and regulation of pH. In phagocytes, robust production of reactive oxygen species occurs in closed membrane compartments, which are called phagosomes. However, direct evidence for the presence of voltage-gated proton channels in phagosome has been lacking. In this study, the expression of voltage-gated proton channels was studied by Western blot with the antibody specific to the voltage-sensor domain protein, VSOP/Hv1, that has recently been identified as the molecular correlate for the voltage-gated proton channel. Phagosomal membranes of neutrophils contain VSOP/Hv1 in accordance with subunits of NADPH oxidases, gp91, p22, p47 and p67. Superoxide anion production upon PMA activation was significantly reduced in neutrophils from VSOP/Hv1 knockout mice. These are consistent with the idea that voltage-gated proton channels help NADPH oxidase in phagocytes to produce reactive oxygen species.

  5. Matrix Configurations for Spherical 4-branes and Non-commutative Structures on S^4

    CERN Document Server

    Nakayama, R; Nakayama, Ryuichi; Shimono, Yusuke

    2004-01-01

    We present a Matrix theory action and Matrix configurations for spherical 4-branes. The dimension of the representations is given by N=2(2j+1) (j=1/2,1,3/2,...). The algebra which defines these configurations is not invariant under SO(5) rotations but under SO(3) \\otimes SO(2). We also construct a non-commutative product for field theories on S^4 in terms of that on S^2. An explicit formula of the non-commutative product which corresponds to the N=4 dim representation of the non-commutative S^4 algebra is worked out. Because we use S^2 \\otimes S^2 parametrization of S^4, our S^4 is doubled and the non-commutative product and functions on S^4 are indeterminate on a great circle (S^1) on S^4. We will however, show that despite this mild singularity it is possible to write down a finite action integral of the non-commutative field thoery on S^4. NS-NS B field background on S^4 which is associated with our Matrix S^4 configurations is also constructed.

  6. A Sentinel Sensor Network for Hydrogen Sensing

    Directory of Open Access Journals (Sweden)

    Andrew J. Mason

    2003-02-01

    Full Text Available A wireless sensor network is presented for in-situ monitoring of atmospheric hydrogen concentration. The hydrogen sensor network consists of multiple sensor nodes, equipped with titania nanotube hydrogen sensors, distributed throughout the area of interest; each node is both sensor, and data-relay station that enables extended wide area monitoring without a consequent increase of node power and thus node size. The hydrogen sensor is fabricated from a sheet of highly ordered titania nanotubes, made by anodization of a titanium thick film, to which platinum electrodes are connected. The electrical resistance of the hydrogen sensor varies from 245 Ω at 500 ppm hydrogen, to 10.23 kΩ at 0 ppm hydrogen (pure nitrogen environment. The measured resistance is converted to voltage, 0.049 V at 500 ppm to 2.046 V at 0 ppm, by interface circuitry. The microcontroller of the sensor node digitizes the voltage and transmits the digital information, using intermediate nodes as relays, to a host node that downloads measurement data to a computer for display. This paper describes the design and operation of the sensor network, the titania nanotube hydrogen sensors with an apparent low level resolution of approximately 0.05 ppm, and their integration in one widely useful device.

  7. Analysis of bias voltage scan data recorded with hybrid Timepix1 silicon pixel assemblies at the DESY testbeam

    CERN Document Server

    Maimon, Shir

    2014-01-01

    This report will present results from the analysis of bias voltage scans in Timepix1 testbeam data. Three assemblies of varying sensor thickness were used to collect data. The effect of the bias voltage on charge sharing, in particular cluster size, was investigated and found to have a significant impact. The effect of the bias voltage on energy collection was also studied, leading to estimates for the depletion voltage, donor concentration, mobility and resistivity of each assembly. Finally, the effect of the bias voltage on the two-hit cluster resolution and detection efficiency was investigated. This report contains extracts from a longer document (LCD-OPEN-2014-001).

  8. Role in fast inactivation of conserved amino acids in the IV/S4-S5 loop of the human muscle Na+ channel.

    Science.gov (United States)

    Mitrovic, N; Lerche, H; Heine, R; Fleischhauer, R; Pika-Hartlaub, U; Hartlaub, U; George, A L; Lehmann-Horn, F

    1996-08-16

    Since it has been shown that point mutations in the S4-S5 loop of the Shaker K+ channel may disrupt fast inactivation, we investigated the role of three conserved amino acids in IV/S4-S5 of the adult human muscle Na+ channel (L1471, S1478, L1482). In contrast to the K+ channel mutations, the analogous substitutions in the Na+ channel (S1478A/C, L1482A) did not substantially affect fast inactivation. Nevertheless, the mutations S1478A/C/Q shifted the voltage dependence of steady-state inactivation; L1471Q and S1478C slowed recovery from inactivation. In contrast, a novel non-conserved IV/S4-S5 mutation causing paramyotonia congenita (F1473S) slowed fast inactivation 2-fold and accelerated recovery from inactivation 5-fold. The results indicate involvement of the IV/ S4-S5 loop of the human muscle Na+ channel in fast inactivation, but different roles for conserved amino acids among Na+ and K+ channels.

  9. Programmable differential capacitance-to-voltage converter for MEMS accelerometers

    Science.gov (United States)

    Royo, G.; Sánchez-Azqueta, C.; Gimeno, C.; Aldea, C.; Celma, S.

    2017-05-01

    Capacitive MEMS sensors exhibit an excellent noise performance, high sensitivity and low power consumption. They offer a huge range of applications, being the accelerometer one of its main uses. In this work, we present the design of a capacitance-to-voltage converter in CMOS technology to measure the acceleration from the capacitance variations. It is based on a low-power, fully-differential transimpedance amplifier with low input impedance and a very low input noise.

  10. Power conditioning for low-voltage piezoelectric stack energy harvesters

    Science.gov (United States)

    Skow, E.; Leadenham, S.; Cunefare, K. A.; Erturk, A.

    2016-04-01

    Low-power vibration and acoustic energy harvesting scenarios typically require a storage component to be charged to enable wireless sensor networks, which necessitates power conditioning of the AC output. Piezoelectric beam-type bending mode energy harvesters or other devices that operate using a piezoelectric element at resonance produce high voltage levels, for which AC-DC converters and step-down DC-DC converters have been previously investigated. However, for piezoelectric stack energy harvesters operating off-resonance and producing low voltage outputs, a step-up circuit is required for power conditioning, such as seen in electromagnetic vibration energy scavengers, RF communications, and MEMS harvesters. This paper theoretically and experimentally investigates power conditioning of a low-voltage piezoelectric stack energy harvester.

  11. A microwave powered sensor assembly for microwave ovens

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention relates to a microwave powered sensor assembly for micro- wave ovens. The microwave powered sensor assembly comprises a microwave antenna for generating an RF antenna signal in response to microwave radiation at a predetermined excitation frequency. A dc power supply circuit...... of the microwave powered sensor assembly is operatively coupled to the RF antenna signal for extracting energy from the RF antenna signal and produce a power supply voltage. A sensor is connected to the power supply voltage and configured to measure a physical or chemical property of a food item under heating...

  12. Temperature and voltage coupling to channel opening in transient receptor potential melastatin 8 (TRPM8).

    Science.gov (United States)

    Raddatz, Natalia; Castillo, Juan P; Gonzalez, Carlos; Alvarez, Osvaldo; Latorre, Ramon

    2014-12-19

    Expressed in somatosensory neurons of the dorsal root and trigeminal ganglion, the transient receptor potential melastatin 8 (TRPM8) channel is a Ca(2+)-permeable cation channel activated by cold, voltage, phosphatidylinositol 4,5-bisphosphate, and menthol. Although TRPM8 channel gating has been characterized at the single channel and macroscopic current levels, there is currently no consensus regarding the extent to which temperature and voltage sensors couple to the conduction gate. In this study, we extended the range of voltages where TRPM8-induced ionic currents were measured and made careful measurements of the maximum open probability the channel can attain at different temperatures by means of fluctuation analysis. The first direct measurements of TRPM8 channel temperature-driven conformational rearrangements provided here suggest that temperature alone is able to open the channel and that the opening reaction is voltage-independent. Voltage is a partial activator of TRPM8 channels, because absolute open probability values measured with fully activated voltage sensors are less than 1, and they decrease as temperature rises. By unveiling the fast temperature-dependent deactivation process, we show that TRPM8 channel deactivation is well described by a double exponential time course. The fast and slow deactivation processes are temperature-dependent with enthalpy changes of 27.2 and 30.8 kcal mol(-1). The overall Q10 for the closing reaction is about 33. A three-tiered allosteric model containing four voltage sensors and four temperature sensors can account for the complex deactivation kinetics and coupling between voltage and temperature sensor activation and channel opening.

  13. Different proportions of C/KCu7S4 hybrid structure for high-performance supercapacitors

    Science.gov (United States)

    Dai, Shuge; Xi, Yi; Hu, Chenguo; Yue, Xule; Cheng, Lu; Wang, Guo

    2014-10-01

    KCu7S4 has the channel structure and minor resistance. Its double larger channels ensure that the ions can well exchange with other's, at the same time, can shorten the ionic diffusion path and improve the ionic and electronic transport. So KCu7S4 shows good electrochemical property. The paper reports a novel and high performance supercapacitor based on hybrid carbon particles and KCu7S4 (C/KCu7S4) electrode. For the hybrid structure with different proportions of C and KCu7S4, the C/KCu7S4 (1:10) hybrid supercapacitor shows preferable electrochemical performance and large specific capacitance (469 mF cm-2) at high charge-discharge rate (2 mA), still retaining ∼95% of the capacitance over 5000 cycles by charge-discharge process at a fixed current of 10 mA. Three supercapacitor units in series can light 50 light-emitting diodes (LEDs) for 2.5 min, 10 LEDs for 4 min, one LED for 5.5 min. The much-increased capacity, rate capability, and cycling stability may be attributed to the superionic conductive KCu7S4 nanowires and C/KCu7S4 hybrid structure, which improve ionic and electronic transport, enhance the kinetics of redox reactions through the electrode system.

  14. Preparation of Cu2ZnSnS4 thin films by hybrid sputtering

    Science.gov (United States)

    Tanaka, Tooru; Nagatomo, Takeshi; Kawasaki, Daisuke; Nishio, Mitsuhiro; Guo, Qixin; Wakahara, Akihiro; Yoshida, Akira; Ogawa, Hiroshi

    2005-11-01

    In order to fabricate Cu2ZnSnS4 thin films, hybrid sputtering system with two sputter sources and two effusion cells is used. The Cu2ZnSnS4 films are fabricated by the sequential deposition of metal elements and annealing in S flux, varying the substrate temperature. The Cu2ZnSnS4 films with stoichiometric composition are obtained at the substrate temperature up to 400 °C, whereas the film composition becomes quite Zn-pool at the substrate temperature above 450 °C. The Cu2ZnSnS4 film shows p-type conductivity, and the optical absorption coefficient and the band gap of the Cu2ZnSnS4 film prepared in this experiment are suitable for fabricating a thin film solar cell.

  15. Multipurpose Electric Potential Sensor for Spacecraft Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is based on a new, compact, solid-state electric potential sensor that has over an order of magnitude lower voltage noise than the prior...

  16. Metamaterial Sensors

    Directory of Open Access Journals (Sweden)

    Jing Jing Yang

    2013-01-01

    Full Text Available Metamaterials have attracted a great deal of attention due to their intriguing properties, as well as the large potential applications for designing functional devices. In this paper, we review the current status of metamaterial sensors, with an emphasis on the evanescent wave amplification and the accompanying local field enhancement characteristics. Examples of the sensors are given to illustrate the principle and the performance of the metamaterial sensor. The paper concludes with an optimistic outlook regarding the future of metamaterial sensor.

  17. Electronic, optical and lattice dynamic properties of the novel diamond-like semiconductors Li2CdGeS4 and Li2CdSnS4

    Science.gov (United States)

    Li, Yanlu; Fan, Weiliu; Sun, Honggang; Cheng, Xiufeng; Li, Pan; Zhao, Xian

    2011-06-01

    Li2CdGeS4 and Li2CdSnS4 are novel quaternary diamond-like semiconductors (DLSs) which have been synthesized recently. We present first-principles calculations of their electronic, optical and lattice dynamic properties with the plane-wave pseudopotential method. We have found an indirect band gap of 2.78 eV for Li2CdGeS4 and a direct band gap of 2.50 eV for Li2CdSnS4. The serious stretching vibrations of the Ge/Sn-S and Li-S bonds may enhance their phonon energies, and cause them to exhibit high heat capacities and Debye temperatures, which are promising for nonlinear optical applications. Compared with Cu-based DLSs, Li plays a key role in enlarging the band gaps and increasing the lattice phonon energies, which would increase the thermal conductivity accompanied by an increase of the optical damage threshold.

  18. Attention Sensor

    NARCIS (Netherlands)

    Börner, Dirk; Kalz, Marco; Specht, Marcus

    2014-01-01

    This software sketch was used in the context of an experiment for the PhD project “Ambient Learning Displays”. The sketch comprises a custom-built attention sensor. The sensor measured (during the experiment) whether a participant looked at and thus attended a public display. The sensor was built us

  19. Attention Sensor

    NARCIS (Netherlands)

    Börner, Dirk; Kalz, Marco; Specht, Marcus

    2014-01-01

    This software sketch was used in the context of an experiment for the PhD project “Ambient Learning Displays”. The sketch comprises a custom-built attention sensor. The sensor measured (during the experiment) whether a participant looked at and thus attended a public display. The sensor was built us

  20. Color Regeneration from Reflective Color Sensor Using an Artificial Intelligent Technique

    Directory of Open Access Journals (Sweden)

    Hayriye Altural

    2010-09-01

    Full Text Available A low-cost optical sensor based on reflective color sensing is presented. Artificial neural network models are used to improve the color regeneration from the sensor signals. Analog voltages of the sensor are successfully converted to RGB colors. The artificial intelligent models presented in this work enable color regeneration from analog outputs of the color sensor. Besides, inverse modeling supported by an intelligent technique enables the sensor probe for use of a colorimetric sensor that relates color changes to analog voltages.

  1. A comprehensive analysis and hardware implementation of control strategies for high output voltage DC-DC boost power converter

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevikumar; Grandi, Gabriele; Blaabjerg, Frede

    2017-01-01

    Classical DC-DC converters used in high voltage direct current (HVDC) power transmission systems, lack in terms of efficiency, reduced transfer gain and increased cost with sensor (voltage/current) numbers. Besides, the internal self-parasitic behavior of the power components reduces the output v...

  2. Proximity and Force Characteristics of CMC Touch Sensor with Square/Dome-shaped Sensor Elements

    Science.gov (United States)

    Kawamura, T.; Inaguma, N.; Kakizaki, Y.; Yamada, H.; Tani, K.

    2013-04-01

    A tactile sensor called Carbon Micro Coil (CMC) touch sensor was developed by CMC Technology Development Co., Ltd. The sensor's elements used in the experiments of this paper are made of silicon rubber containing CMCs several micrometers in diameter. One of the elements is molded into a square 30 mm on a side and 3 mm thick; the other is a dome 16 mm in diameter and 2 mm height. CMCs in the sensor element contribute to the electrical conductivity and the sensor element is considered to constitute an LCR circuit. When an object approaches to the sensor element or the sensor element is deformed mechanically, the impedance changes, and the CMC sensor detects the impedance changes by measuring the modulation of amplitude and phase of an input excitation signal to the sensor element. The CMC sensor also creates voltage signals of the R- and LC-components separately according to the amplitude and phase modulation. In this paper, the characteristics of the CMC sensor with respect to its proximity and force senses are investigated. First, the output of the CMC sensor with the square-shaped sensor element is measured when an object approaches to the sensor element. Next, the output of the CMC sensor with the dome-shaped sensor element is measured when fine deformations of 1 to 5 μm are applied to the sensor element under variable compression force. The results suggest that the CMC sensor can measure the force variance applied to the sensor element as well as the distance between the sensor element and an object.

  3. Enhanced visible light photocatalytic activity of ZnIn2S4 modified by semiconductors.

    Science.gov (United States)

    Yang, Sai; Li, Li; Yuan, Wenhui; Xia, Zilong

    2015-04-14

    To improve the visible light photocatalytic activity of a ZnIn2S4 sample, we synthesized two kinds of coupled-photocatalysts: TiO2@ZnIn2S4 core-shell type heterostructure composites by a simple and flexible hydrothermal route using TiO2 as the precursor and CuO/ZnIn2S4 contact type heterostructure composites incorporated with different amounts of CuO by the impregnation-calcination method. These as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Visible absorption spectra (UV-Vis) and nitrogen adsorption measurements. An enhancement in photocatalytic activity was observed after the addition of TiO2 and CuO. It was found that the as-synthesized TiO2@ZnIn2S4 photocatalyst was more efficient than TiO2 and ZnIn2S4 in the photocatalytic degradation of methylene blue (MB). TEM images confirmed that the TiO2@ZnIn2S4 nanoparticles possessed a well-proportioned core-shell morphology. On the other hand, the effects of CuO loading amount on the crystal structure, and photocatalytic properties of CuO/ZnIn2S4 samples for MB degradation under visible light irradiation were investigated, suggesting that the introduction of CuO could influence the morphology and BET specific surface area of the ZnIn2S4 sample and enhance the visible light absorption of photocatalysts. The photocatalytic degradation performance of MB was remarkably improved in the presence of CuO/ZnIn2S4 compared to pure ZnIn2S4 and 10 mol% CuO/ZnIn2S4 was found to possess the optimal photocatalytic performance. Moreover, mechanisms for the enhanced photocatalytic activity of the TiO2@ZnIn2S4 and CuO/ZnIn2S4 composites were proposed.

  4. Simulation Research on Self-compensation Technique of Temperature-induced Scale Factor Error for Optical Voltage Sensor%光学电压互感器变比温度误差自补偿技术仿真研究

    Institute of Scientific and Technical Information of China (English)

    李传生; 荆平; 张朝阳; 孙海江

    2014-01-01

    变比温度误差是限制光学电压互感器实用化的主要因素。分析Faraday旋光器及BGO晶体线性电光系数的温度相关性对互感器变比的影响机制,提出一种基于Faraday旋光角温度特性及其对互感器变比的影响自动补偿BGO晶体电光系数温度相关性的变比误差自补偿方法。仿真结果表明:在–40+70℃,对于温度系数为0.04/℃的Faraday旋光器,当常温下Faraday旋光角在41.643.2时,变比误差在0.5%以内;当常温下Faraday旋光角为42.3时,互感器的变比误差最小,约为0.3%。要使补偿后互感器的变比误差小于0.2%,Faraday 旋光角的温度系数应小于0.03/℃。该方法为光学电压互感器变比温度误差的抑制提供新途径。%The temperature-induced scale factor error is a primary constraint on the practical applications of the optical voltage sensor (OVS). The effect mechanism of the temperature-dependent rotation angle of the Faraday rotator and the temperature-dependent linear electro-optic coefficient of the BGO crystal on the scale factor is analyzed. The method utilizing the temperature dependence of the Faraday rotator and its effect on the scale factor to self-compensate the scale factor error of the temperature-dependent electro-optic coefficient of the BGO crystal is presented. Over the temperature range from –40℃ to +70℃, if the temperature coefficient of the Faraday rotation angle is 0.04/℃, the rotation angle at room temperature must be set between 41.6 and 43.2 to ensure the scale factor error of the sensor to be within0.5%. In addition, when the rotation angle at room temperature is 42.3, the scale factor error obtains the minimum 0.3%. If the scale factor error of the sensor is required to be controlled within0.2% after compensation, the temperature coefficient of the Faraday rotation angle must be less than 0.03/℃. The proposed method offers a potential

  5. Wide Dynamic Range CMOS Potentiostat for Amperometric Chemical Sensor

    OpenAIRE

    Wei-Song Wang; Wei-Ting Kuo; Hong-Yi Huang; Ching-Hsing Luo

    2010-01-01

    Presented is a single-ended potentiostat topology with a new interface connection between sensor electrodes and potentiostat circuit to avoid deviation of cell voltage and linearly convert the cell current into voltage signal. Additionally, due to the increased harmonic distortion quantity when detecting low-level sensor current, the performance of potentiostat linearity which causes the detectable current and dynamic range to be limited is relatively decreased. Thus, to alleviate these irreg...

  6. MAu2GeS4-Chalcogel (M = Co, Ni): Heterogeneous Intra- and Intermolecular Hydroamination Catalysts

    KAUST Repository

    Davaasuren, Bambar

    2017-08-08

    High surface area macroporous chalcogenide aerogels (chalcogels) MAu2GeS4 (M = Co, Ni) were prepared from K2Au2GeS4 precursor and Co(OAc)2 or NiCl2 by one-pot sol-gel metathesis reactions in aqueous media. The MAu2GeS4-chalcogels were screened for catalytic intramolecular hydroamination of 4-pentyn-1-amine substrate at different temperatures. 87% and 58% conversion was achieved at 100 °C, using CoAu2GeS4- and NiAu2GeS4-chalcogels respectively, and the reaction kinetics follows the first order. It was established that the catalytic performance of the aerogels is associated with the M(2+) centers present in the structure. Intermolecular hydroamination of aniline with 1-R-4-ethynylbenzene (R = -H, -OCH3, -Br, -F) was carried out at 100 °C using CoAu2GeS4-chalcogel catalyst, due to its promising catalytic performance. The CoAu2GeS4-chalcogel regioselectively converted the pair of substrates to respective Markovnikov products, (E)-1-(4-R-phenyl)-N-phenylethan-1-imine, with 38% to 60% conversion.

  7. Low Voltage Power Supply Incorporating Ceramic Transformer

    CERN Document Server

    Imori, M

    2007-01-01

    A low voltage power supply provides the regulated output voltage of 1 V from the supply voltage around 48 V. The low voltage power supply incorporates a ceramic transformer which utilizes piezoelectric effect to convert voltage. The ceramic transformer isolates the secondary from the primary, thus providing the ground isolation between the supply and the output voltages. The ceramic transformer takes the place of the conventional magnetic transformer. The ceramic transformer is constructed from a ceramic bar and does not include any magnetic material. So the low voltage power supply can operate under a magnetic field. The output voltage is stabilized by feedback. A feedback loop consists of an error amplifier, a voltage controlled oscillator and a driver circuit. The amplitude ratio of the transformer has dependence on the frequency, which is utilized to stabilize the output voltage. The low voltage power supply is investigated on the analogy of the high voltage power supply similarly incorporating the cerami...

  8. Detailed Study of Amplitude Nonlinearity in Piezoresistive Force Sensors

    Directory of Open Access Journals (Sweden)

    Pablo Gonzalez De Santos

    2011-09-01

    Full Text Available This article upgrades the RC linear model presented for piezoresistive force sensors. Amplitude nonlinearity is found in sensor conductance, and a characteristic equation is formulated for modeling its response under DC-driving voltages below 1 V. The feasibility of such equation is tested on four FlexiForce model A201-100 piezoresistive sensors by varying the sourcing voltage and the applied forces. Since the characteristic equation proves to be valid, a method is presented for obtaining a specific sensitivity in sensor response by calculating the appropriate sourcing voltage and feedback resistor in the driving circuit; this provides plug-and-play capabilities to the device and reduces the start-up time of new applications where piezoresistive devices are to be used. Finally, a method for bypassing the amplitude nonlinearity is presented with the aim of reading sensor capacitance.

  9. Detailed study of amplitude nonlinearity in piezoresistive force sensors.

    Science.gov (United States)

    Paredes-Madrid, Leonel; Emmi, Luis; Garcia, Elena; de Santos, Pablo Gonzalez

    2011-01-01

    This article upgrades the RC linear model presented for piezoresistive force sensors. Amplitude nonlinearity is found in sensor conductance, and a characteristic equation is formulated for modeling its response under DC-driving voltages below 1 V. The feasibility of such equation is tested on four FlexiForce model A201-100 piezoresistive sensors by varying the sourcing voltage and the applied forces. Since the characteristic equation proves to be valid, a method is presented for obtaining a specific sensitivity in sensor response by calculating the appropriate sourcing voltage and feedback resistor in the driving circuit; this provides plug-and-play capabilities to the device and reduces the start-up time of new applications where piezoresistive devices are to be used. Finally, a method for bypassing the amplitude nonlinearity is presented with the aim of reading sensor capacitance.

  10. Modular High Voltage Power Supply

    Energy Technology Data Exchange (ETDEWEB)

    Newell, Matthew R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-18

    The goal of this project is to develop a modular high voltage power supply that will meet the needs of safeguards applications and provide a modular plug and play supply for use with standard electronic racks.

  11. Voltage-controlled metal binding on polyelectrolyte-functionalized nanopores.

    Science.gov (United States)

    Actis, Paolo; Vilozny, Boaz; Seger, R Adam; Li, Xiang; Jejelowo, Olufisayo; Rinaudo, Marguerite; Pourmand, Nader

    2011-05-17

    Most of the research in the field of nanopore-based platforms is focused on monitoring ion currents and forces as individual molecules translocate through the nanopore. Molecular gating, however, can occur when target analytes interact with receptors appended to the nanopore surface. Here we show that a solid state nanopore functionalized with polyelectrolytes can reversibly bind metal ions, resulting in a reversible, real-time signal that is concentration dependent. Functionalization of the sensor is based on electrostatic interactions, requires no covalent bond formation, and can be monitored in real time. Furthermore, we demonstrate how the applied voltage can be employed to tune the binding properties of the sensor. The sensor has wide-ranging applications and, its simplest incarnation can be used to study binding thermodynamics using purely electrical measurements with no need for labeling.

  12. Reliability criteria for voltage stability

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Carson W.; Silverstein, Brian L. [Bonneville Power Administration, Portland, OR (United States)

    1994-12-31

    In face of costs pressures, there is need to allocate scare resources more effectively in order to achieve voltage stability. This naturally leads to development of probabilistic criteria and notions of rick management. In this paper it is presented a discussion about criteria for long term voltage stability limited to the case in which the time frames are topically several minutes. (author) 14 refs., 1 fig.

  13. A Voltage Quality Detection Method

    DEFF Research Database (Denmark)

    Chen, Zhe; Wei, Mu

    2008-01-01

    This paper presents a voltage quality detection method based on a phase-locked loop (PLL) technique. The technique can detect the voltage magnitude and phase angle of each individual phase under both normal and fault power system conditions. The proposed method has the potential to evaluate vario...... power quality disturbances, such as interruptions, sags and imbalances. Simulation studies have been performed. The effectiveness of the proposed method has been demonstrated under the simulated typical power disturbances....

  14. Small, Inexpensive Combined NOx Sensor and O2 Sensor

    Energy Technology Data Exchange (ETDEWEB)

    W. N. Lawless; C. F. Clark, Jr.

    2008-09-08

    electronic control units were designed and built. One control unit provides independent constant voltages to the NOx and oxygen sensors and reads the current from them (that is, detects the amount of test gas present). The second controller holds the fully-assembled sensor at the desired operating temperature and controllably pumps excess oxygen from the test chamber. While the development of the sensor body was a complete success, the development of the packaging was only partially successful. All of the basic principles were demonstrated, but the packaging was too complex to optimize the operation within the resources of the program. Thus, no fully-assembled sensors were sent to outside labs for testing of cross-sensitivities, response times, etc. Near the end of the program, Sensata Technologies of Attleboro, MA tested the sensor bodies and confirmed the CeramPhysics measurements as indicated in the following attached letter. Sensata was in the process of designing their own packaging for the sensor and performing cross-sensitivity tests when they stopped all sensor development work due to the automotive industry downturn. Recently Ceramatec Inc. of Salt Lake City has expressed an interest in testing the sensor, and other licensing opportunities are being pursued.

  15. A matter of quantum voltages.

    Science.gov (United States)

    Sellner, Bernhard; Kathmann, Shawn M

    2014-11-14

    Voltages inside matter are relevant to crystallization, materials science, biology, catalysis, and aqueous chemistry. The variation of voltages in matter can be measured by experiment, however, modern supercomputers allow the calculation of accurate quantum voltages with spatial resolutions of bulk systems well beyond what can currently be measured provided a sufficient level of theory is employed. Of particular interest is the Mean Inner Potential (V(o))--the spatial average of these quantum voltages referenced to the vacuum. Here we establish a protocol to reliably evaluate V(o) from quantum calculations. Voltages are very sensitive to the distribution of electrons and provide metrics to understand interactions in condensed phases. In the present study, we find excellent agreement with measurements of V(o) for vitrified water and salt crystals and demonstrate the impact of covalent and ionic bonding as well as intermolecular/atomic interactions. Certain aspects in this regard are highlighted making use of simple model systems/approximations. Furthermore, we predict V(o) as well as the fluctuations of these voltages in aqueous NaCl electrolytes and characterize the changes in their behavior as the resolution increases below the size of atoms.

  16. VOLTAGE COMPENSATION USING ARTIFICIAL NEURAL NETWORK

    African Journals Online (AJOL)

    VOLTAGE COMPENSATION USING ARTIFICIAL NEURAL NETWORK: A CASE STUDY OF RUMUOLA DISTRIBUTION NETWORK. ... The artificial neural networks controller engaged to controlling the dynamic voltage ... Article Metrics.

  17. 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.

  18. Cation/Anion Substitution in Cu2ZnSnS4 for Improved Photovoltaic Performance

    OpenAIRE

    Balakrishna Ananthoju; Jeotikanta Mohapatra; Jangid, Manoj K.; Bahadur, D.; Medhekar, N. V.; ASLAM, M.

    2016-01-01

    Cations and anions are replaced with Fe, Mn, and Se in CZTS in order to control the formations of the secondary phase, the band gap, and the micro structure of Cu2ZnSnS4. We demonstrate a simplified synthesis strategy for a range of quaternary chalcogenide nanoparticles such as Cu2ZnSnS4 (CZTS), Cu2FeSnS4 (CFTS), Cu2MnSnS4 (CMTS), Cu2ZnSnSe4 (CZTSe), and Cu2ZnSn(S0.5Se0.5)4 (CZTSSe) by thermolysis of metal chloride precursors using long chain amine molecules. It is observed that the crystal s...

  19. Spin dynamics and spin freezing in the triangular lattice antiferromagnets FeGa2S4 and NiGa2S4

    Science.gov (United States)

    Zhao, Songrui; Dalmas de Réotier, P.; Yaouanc, A.; MacLaughlin, D. E.; Mackie, J. M.; Bernal, O. O.; Nambu, Y.; Higo, T.; Nakatsuji, S.

    2012-08-01

    Magnetic susceptibility and muon spin relaxation (μSR) experiments have been carried out on the quasi-2D triangular-lattice spin S=2 antiferromagnet FeGa2S4. The μSR data indicate a sharp onset of a frozen or nearly frozen spin state at T*=31(2) K, twice the spin-glass-like freezing temperature Tf=16(1) K. The susceptibility becomes field dependent below T*, but no sharp anomaly is observed in any bulk property. A similar transition is observed in μSR data from the spin-1 isomorph NiGa2S4. In both compounds the dynamic muon spin relaxation rate λd(T) above T* agrees well with a calculation of spin-lattice relaxation by Chubukov, Sachdev, and Senthil in the renormalized classical regime of a 2D frustrated quantum antiferromagnet. There is no firm evidence for other mechanisms. At low temperatures, λd(T) becomes temperature independent in both compounds, indicating persistence of spin dynamics. Scaling of λd(T) between the two compounds is observed from ˜Tf to ˜1.5T*. Although the μSR data by themselves cannot exclude a truly static spin component below T*, together with the susceptibility data they are consistent with a slowly fluctuating “spin gel” regime between Tf and T*. Such a regime and the absence of a divergence in λd(T) at T* are features of two unconventional mechanisms: (1) binding/unbinding of Z2 vortex excitations, and (2) impurity spins in a nonmagnetic spin-nematic ground state. The absence of a sharp anomaly or history dependence at T* in the susceptibility of FeGa2S4, and the weakness of such phenomena in NiGa2S4, strongly suggest transitions to low-temperature phases with unconventional dynamics.

  20. Horizontal gene transfer of zinc and non-zinc forms of bacterial ribosomal protein S4

    Directory of Open Access Journals (Sweden)

    Luthey-Schulten Zaida

    2009-07-01

    Full Text Available Abstract Background The universal ribosomal protein S4 is essential for the initiation of small subunit ribosomal assembly and translational accuracy. Being part of the information processing machinery of the cell, the gene for S4 is generally thought of as being inherited vertically and has been used in concatenated gene phylogenies. Here we report the evolution of ribosomal protein S4 in relation to a broad sharing of zinc/non-zinc forms of the gene and study the scope of horizontal gene transfer (HGT of S4 during bacterial evolution. Results In this study we present the complex evolutionary history of ribosomal protein S4 using 660 bacterial genomes from 16 major bacterial phyla. According to conserved characteristics in the sequences, S4 can be classified into C+ (zinc-binding and C- (zinc-free variants, with 26 genomes (mainly from the class Clostridia containing genes for both. A maximum likelihood phylogenetic tree of the S4 sequences was incongruent with the standard bacterial phylogeny, indicating a departure from strict vertical inheritance. Further analysis using the genome content near the S4 genes, which are usually located in a conserved gene cluster, showed not only that HGT of the C- gene had occurred at various stages of bacterial evolution, but also that both the C- and C+ genes were present before the individual phyla diverged. To explain the latter, we theorize that a gene pool existed early in bacterial evolution from which bacteria could sample S4 gene variants, according to environmental conditions. The distribution of the C+/- variants for seven other zinc-binding ribosomal proteins in these 660 bacterial genomes is consistent with that seen for S4 and may shed light on the evolutionary pressures involved. Conclusion The complex history presented for "core" protein S4 suggests the existence of a gene pool before the emergence of bacterial lineages and reflects the pervasive nature of HGT in subsequent bacterial evolution

  1. Electrical Characteristics of Silicon Pixel Sensors

    CERN Document Server

    Gorelov, I; Hoeferkamp, M; Mata-Bruni, V; Santistevan, G; Seidel, S C; Ciocio, A; Einsweiler, K F; Emes, J; Gilchriese, M G D; Joshi, A; Kleinfelder, S A; Marchesini, R; McCormack, F; Milgrome, O; Palaio, N; Pengg, F; Richardson, J; Zizka, G; Ackers, M; Comes, G; Fischer, P; Keil, M; Klasen, V; Kühl, T; Meuser, S; Ockenfels, W; Raith, B; Treis, J; Wermes, N; Gössling, C; Hügging, F G; Klaiber Lodewigs, Jonas M; Krasel, O; Wüstenfeld, J; Wunstorf, R; Barberis, D; Beccherle, R; Caso, Carlo; Cervetto, M; Darbo, G; Gagliardi, G; Gemme, C; Morettini, P; Netchaeva, P; Osculati, B; Rossi, L; Charles, E; Fasching, D; Blanquart, L; Breugnon, P; Calvet, D; Clemens, J-C; Delpierre, P A; Hallewell, G D; Laugier, D; Mouthuy, T; Rozanov, A; Valin, I; Andreazza, A; Caccia, M; Citterio, M; Lari, T; Meroni, C; Ragusa, F; Troncon, C; Vegni, G; Lutz, Gerhard; Richter, R H; Rohe, T; Boyd, GR; Skubic, P L; Sícho, P; Tomasek, L; Vrba, V; Holder, M; Ziolkowski, M; Cauz, D; Cobal-Grassmann, M; D'Auria, S; De Lotto, B; del Papa, C; Grassmann, H; Santi, L; Becks, K H; Lenzen, G; Linder, C

    2001-01-01

    Prototype sensors for the ATLAS silicon pixel detector have been electrically characterized. The current and voltage characteristics, charge collection efficiencies, and resolutions have been examined. Devices were fabricated on oxygenated and standard detector-grade silicon wafers. Results from prototypes which examine p-stop and standard and moderated p-spray isolation are presented for a variety of geometrical options. Some of the comparisons relate unirradiated sensors with those that have received fluences relevant to LHC operation.

  2. Meeting power requirements for organic printed sensor tags (Conference Presentation)

    Science.gov (United States)

    Ng, Tse Nga; Mei, Ping; Schwartz, David E.; Veres, Janos; Broms, Per; Karlsson, Christer

    2016-11-01

    In electronic systems, components often require different supply voltage for operation. In order to meet this requirement and to optimize power consumption for flexible electronics, we demonstrate a pulsed voltage multiplier that boosts the voltage at specific circuit nodes above the supply voltage. A five-stage pulsed voltage multiplier is shown to provide an output voltage up to 18 V from a supply voltage of 10 V, with minimum 10 ms pulse rise time for a 70 pF load. A key requirement for the pulsed voltage multiplier circuit is low device leakage to boost the output voltage level. To minimize leakage, the composition of the organic semiconducting layer is modified by blending an insulating polymer with the small molecule semiconductor. This modification allows control over the transistor turn-on voltage, which enables low leakage current required for operation of the circuits. The printed multiplier allows a single power source to deliver multiple voltage levels and enables integration of lower voltage logic with components that require higher operating voltage, for example, in the case of recording data into memory cells in sensor tags.

  3. Modulation of decoding fidelity by ribosomal proteins S4 and S5.

    Science.gov (United States)

    Agarwal, Deepali; Kamath, Divya; Gregory, Steven T; O'Connor, Michael

    2015-03-01

    Ribosomal proteins S4 and S5 participate in the decoding and assembly processes on the ribosome and the interaction with specific antibiotic inhibitors of translation. Many of the characterized mutations affecting these proteins decrease the accuracy of translation, leading to a ribosomal-ambiguity phenotype. Structural analyses of ribosomal complexes indicate that the tRNA selection pathway involves a transition between the closed and open conformations of the 30S ribosomal subunit and requires disruption of the interface between the S4 and S5 proteins. In agreement with this observation, several of the mutations that promote miscoding alter residues located at the S4-S5 interface. Here, the Escherichia coli rpsD and rpsE genes encoding the S4 and S5 proteins were targeted for mutagenesis and screened for accuracy-altering mutations. While a majority of the 38 mutant proteins recovered decrease the accuracy of translation, error-restrictive mutations were also recovered; only a minority of the mutant proteins affected rRNA processing, ribosome assembly, or interactions with antibiotics. Several of the mutations affect residues at the S4-S5 interface. These include five nonsense mutations that generate C-terminal truncations of S4. These truncations are predicted to destabilize the S4-S5 interface and, consistent with the domain closure model, all have ribosomal-ambiguity phenotypes. A substantial number of the mutations alter distant locations and conceivably affect tRNA selection through indirect effects on the S4-S5 interface or by altering interactions with adjacent ribosomal proteins and 16S rRNA.

  4. Neural network-based sensor signal accelerator.

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, M. C.

    2000-10-16

    A strategy has been developed to computationally accelerate the response time of a generic electronic sensor. The strategy can be deployed as an algorithm in a control system or as a physical interface (on an embedded microcontroller) between a slower responding external sensor and a higher-speed control system. Optional code implementations are available to adjust algorithm performance when computational capability is limited. In one option, the actual sensor signal can be sampled at the slower rate with adaptive linear neural networks predicting the sensor's future output and interpolating intermediate synthetic output values. In another option, a synchronized collection of predictors sequentially controls the corresponding synthetic output voltage. Error is adaptively corrected in both options. The core strategy has been demonstrated with automotive oxygen sensor data. A prototype interface device is under construction. The response speed increase afforded by this strategy could greatly offset the cost of developing a replacement sensor with a faster physical response time.

  5. Facile synthesis of hybrid CNTs/NiCo2S4 composite for high performance supercapacitors.

    Science.gov (United States)

    Li, Delong; Gong, Youning; Pan, Chunxu

    2016-07-11

    In this work, a novel carbon nanotubes (CNTs)/NiCo2S4 composite for high performance supercapacitors was prepared via a simple chemical bath deposition combined with a post-anion exchange reaction. The morphologies and phase structures of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and low-temperature sorption of nitrogen (BET). The electro-chemical tests revealed that the CNT/NiCo2S4 composite exhibited high electrochemical performance, because the CNTs were used as a conductive network for the NiCo2S4 hexagonal nanoplates. Compared with pure NiCo2S4 and the mechanically mixed CNTs/NiCo2S4 composite, the CNTs/NiCo2S4 composite electrode material exhibited excellent supercapacitive performance, such as a high specific capacitance up to 1537 F/g (discharge current density of 1 A/g) and an outstanding rate capability of 78.1% retention as the discharge current density increased to 100 A/g. It is therefore expected to be a promising alternative material in the area of energy storage.

  6. Quaternary Cu2ZnSnS4 quantum dot-sensitized solar cells: Synthesis, passivation and ligand exchange

    Science.gov (United States)

    Bai, Bing; Kou, Dongxing; Zhou, Wenhui; Zhou, Zhengji; Tian, Qingwen; Meng, Yuena; Wu, Sixin

    2016-06-01

    The quaternary Cu2ZnSnS4 (CZTS) QDs had been successfully introduced into quantum dot-sensitized solar cells (QDSC) via hydrolysis approach in our previous work [Green Chem. 2015, vol. 17, p. 4377], but the obtained cell efficiency was still limited by low open-circuit voltage and fill factor. Herein, we use 1-dodecanethiol (DDT) as capping ligand for fairly small-sized CZTS QDs synthesis to improve their intrinsic properties. Since this strong bonded capping ligand can not be replaced by 3-mercaptopropionic acid (MPA) directly, the nature cation (Cu, Zn or Sn)-DDT units of QDs are first exchanged by the preconjugated Cd-oleate via successive ionic layer adsorption and reaction (SILAR) procedure accompanied with the formation of a core/shell structure. The weak bonded oleic acid (OA) can be finally replaced by MPA and the constructed water soluble CZTS/CdSe QDSC achieves an impressive conversion efficiency of 4.70%. The electron transport and recombination dynamic processes are confirmed by intensity-modulated photocurrent spectroscopy (IMPS)/intensity-modulated photovoltage spectroscopy (IMVS) measurements. It is found that the removal of long alkyl chain is conducive to improve the electron transport process and the type-II core/shell structure is beneficial to accelerate electron transport and retard charge recombination. This effective ligand removal strategy is proved to be more convenient for the applying of quaternary QDs in QDSC and would boost a more powerful efficiency in the future work.

  7. Metal Disorder in Cu2ZnSnS4 (CZTS) Solar Cells from Multi-Scale Simulations

    Science.gov (United States)

    Wallace, Suzanne; Frost, Jarvist; Walsh, Aron

    Kesterite-structured Cu2ZnSnS4 (CZTS) is a promising earth-abundant and non-toxic material for the active layer of thin-film solar cells due to its high optical absorption coefficient of >104 cm-1 and sunlight matched band gap of 1.5 eV. Device efficiencies are hampered by low open circuit voltage (VOC) compared to the optical band gap. One possible origin of this is disorder amongst the Cu and Zn ions. Such disorder could lead to sub band-gap recombination centres due to fluctuations in electrostatic potential from the presence of charged defects. Understanding the origin of these sub-gap states, and the resulting impediment on device performance, is essential to discover design and processing rules for high efficiency kesterite, and other multi-component semiconductor, devices. We investigate this by writing custom Monte-Carlo codes to simulate the on-lattice disorder. A generalised Ising Hamiltonian is parameterised with hybrid density functional theory (DFT) total-energy calculations on defect pairs. The resulting disorder is simulated as a function of temperature, and the order-disorder behaviour and resulting local and long-range electrostatic potential variation due to Cu-Zn disorder is quantified.

  8. Sensor Compendium

    CERN Document Server

    Artuso, M; Bolla, G; Bortoletto, D; Caberera, B; Carlstrom, J E; Chang, C L; Cooper, W; Da Via, C; Demarteau, M; Fast, J; Frisch, H; Garcia-Sciveres, M; Golwala, S; Haber, C; Hall, J; Hoppe, E; Irwin, K D; Kagan, H; Kenney, C; Lee, A T; Lynn, D; Orrell, J; Pyle, M; Rusack, R; Sadrozinski, H; Sanchez, M C; Seiden, A; Trischuk, W; Vavra, J; Wetstein, M; Zhu, R-Y

    2013-01-01

    Sensors play a key role in detecting both charged particles and photons for all three frontiers in Particle Physics. The signals from an individual sensor that can be used include ionization deposited, phonons created, or light emitted from excitations of the material. The individual sensors are then typically arrayed for detection of individual particles or groups of particles. Mounting of new, ever higher performance experiments, often depend on advances in sensors in a range of performance characteristics. These performance metrics can include position resolution for passing particles, time resolution on particles impacting the sensor, and overall rate capabilities. In addition the feasible detector area and cost frequently provides a limit to what can be built and therefore is often another area where improvements are important. Finally, radiation tolerance is becoming a requirement in a broad array of devices. We present a status report on a broad category of sensors, including challenges for the future ...

  9. Wind Sensor

    OpenAIRE

    Li, Jiaoyang; Ni, Jiqin

    2014-01-01

    Wind measurement is needed in many practical and scientific research situations. Some specific applications require to precisely measuring both wind direction and wind speed at the same time. Current commercial sensors for wind direction and wind speed measurement usually use ultrasonic technology and the sensors are very expensive (> $1500). In addition, the sensors are large in dimension and cannot measure airflow patterns in high spatial resolution. Therefore new and low cost wind speed an...

  10. A Differential Reflective Intensity Optical Fiber Angular Displacement Sensor.

    Science.gov (United States)

    Jia, Binghui; He, Lei; Yan, Guodong; Feng, Yong

    2016-09-16

    In this paper, a novel differential reflective intensity optical fiber angular displacement sensor was proposed. This sensor can directly measure the angular and axial linear displacement of a flat surface. The structure of the sensor probe is simple and its basic principle was first analyzed according to the intensity modulation mechanisms. Secondly, in order to trim the dark output voltage to zero, the photoelectric conversion circuit was developed to adjust the signals. Then, the sensor model including the photoelectric conversion circuit has been established, and the influence of design parameters on the sensor output characteristic has been simulated. Finally, the design parameters of the sensor structure were obtained based on the simulation results; and an experimental test system was built for the sensor calibration. Experimental results show that the linear angular range and the sensitivity of the sensor were 74.4 and 0.051 V/°, respectively. Its change rules confirm the operating principle of the sensor well.

  11. A Differential Reflective Intensity Optical Fiber Angular Displacement Sensor

    Science.gov (United States)

    Jia, Binghui; He, Lei; Yan, Guodong; Feng, Yong

    2016-01-01

    In this paper, a novel differential reflective intensity optical fiber angular displacement sensor was proposed. This sensor can directly measure the angular and axial linear displacement of a flat surface. The structure of the sensor probe is simple and its basic principle was first analyzed according to the intensity modulation mechanisms. Secondly, in order to trim the dark output voltage to zero, the photoelectric conversion circuit was developed to adjust the signals. Then, the sensor model including the photoelectric conversion circuit has been established, and the influence of design parameters on the sensor output characteristic has been simulated. Finally, the design parameters of the sensor structure were obtained based on the simulation results; and an experimental test system was built for the sensor calibration. Experimental results show that the linear angular range and the sensitivity of the sensor were 74.4 and 0.051 V/°, respectively. Its change rules confirm the operating principle of the sensor well. PMID:27649199

  12. Electrode voltage fall and total voltage of a transient arc

    Science.gov (United States)

    Valensi, F.; Ratovoson, L.; Razafinimanana, M.; Masquère, M.; Freton, P.; Gleizes, A.

    2016-06-01

    This paper deals with an experimental study of the components of a transient arc total voltage with duration of a few tens of ms and a current peak close to 1000 A. The cathode tip is made of graphite whereas the flat anode is made either of copper or of graphite; the electrodes gap is a few mm. The analysis of the electrical parameters is supported and validated by fast imaging and by two models: the first one is a 2D physical model of the arc allowing to calculate both the plasma temperature field and the arc voltage; the second model is able to estimate the transient heating of the graphite electrode. The main aim of the study was to detect the possible change of the cathode voltage fall (CVF) during the first instants of the arc. Indeed it is expected that during the first ms the graphite cathode is rather cool and the main mechanism of the electron emission should be the field effect emission, whereas after several tens of ms the cathode is strongly heated and thermionic emission should be predominant. We have observed some change in the apparent CVF but we have shown that this apparent change can be attributed to the variation of the solid cathode resistance. On the other hand, the possible change of CVF corresponding to the transition between a ‘cold’ and a ‘hot’ cathode should be weak and could not be characterized considering our measurement uncertainty of about 2 V. The arc column voltage (ACV) was estimated by subtracting the electrode voltage fall from the total arc voltage. The experimental transient evolution of the ACV is in very good agreement with the theoretical variation predicted by the model, showing the good ability of the model to study this kind of transient arc.

  13. Gas Sensor

    KAUST Repository

    Luebke, Ryan

    2015-01-22

    A gas sensor using a metal organic framework material can be fully integrated with related circuitry on a single substrate. In an on-chip application, the gas sensor can result in an area-efficient fully integrated gas sensor solution. In one aspect, a gas sensor can include a first gas sensing region including a first pair of electrodes, and a first gas sensitive material proximate to the first pair of electrodes, wherein the first gas sensitive material includes a first metal organic framework material.

  14. Sensor web

    Science.gov (United States)

    Delin, Kevin A. (Inventor); Jackson, Shannon P. (Inventor)

    2011-01-01

    A Sensor Web formed of a number of different sensor pods. Each of the sensor pods include a clock which is synchronized with a master clock so that all of the sensor pods in the Web have a synchronized clock. The synchronization is carried out by first using a coarse synchronization which takes less power, and subsequently carrying out a fine synchronization to make a fine sync of all the pods on the Web. After the synchronization, the pods ping their neighbors to determine which pods are listening and responded, and then only listen during time slots corresponding to those pods which respond.

  15. Unbalanced Voltage Compensation in Low Voltage Residential AC Grids

    DEFF Research Database (Denmark)

    Trintis, Ionut; Douglass, Philip; Munk-Nielsen, Stig

    2016-01-01

    This paper describes the design and test of a control algorithm for active front-end rectifiers that draw power from a residential AC grid to feed heat pump loads. The control algorithm is able to control the phase to neutral or phase to phase RMS voltages at the point of common coupling....... The voltage control was evaluated with either active or reactive independent phase load current control. The control performance in field operation in a residential grid situated in Bornholm, Denmark was investigated for different use cases....

  16. Highly Accurate Derivatives for LCL-Filtered Grid Converter with Capacitor Voltage Active Damping

    DEFF Research Database (Denmark)

    Xin, Zhen; Loh, Poh Chiang; Wang, Xiongfei

    2016-01-01

    The middle capacitor voltage of an LCL-filter, if fed back for synchronization, can be used for active damping. An extra sensor for measuring the capacitor current is then avoided. Relating the capacitor voltage to existing popular damping techniques designed with capacitor current feedback would...... are then proposed, based on either second-order or non-ideal generalized integrator. Performances of these derivatives have been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately. Experimental results presented have verified...

  17. Digital Realization of Capacitor-Voltage Feedback Active Damping for LCL-Filtered Grid Converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    The capacitor voltage of an LCL-filter can also be used for active damping, if it is fed back for synchronization. By this way, an extra current sensor can be avoided. Compared with the existing active damping techniques designed with capacitor current feedback, the capacitor voltage feedback....... To overcome their drawbacks, a new derivative method is then proposed, based on the non-ideal generalized integrator. The performance of the proposed derivative has been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately...

  18. Gas sensing properties of branched carbon nanotube-based structures using a novel low voltage emission.

    Science.gov (United States)

    Darbari, S; Azimi, S; Abdi, Y; Mohajerzadeh, S

    2012-11-01

    Branched carbon nanostructures have been successfully grown on interdigital comb-like structures for a gas sensing application. Field emission scanning electron microscopy has been utilized to investigate the morphology and structure of the grown nanostructures at different stages of growth process. Tunneling current of the fabricated sensor has been measured when a monotonically increasing voltage is applied between the electrodes. The effect of exposure to three different gases on the measured current has been studied. A data processing on the measured current voltage characteristics results in the evolution of various peaks at distinct voltages which depends on the type of the gas.

  19. Automated Voltage Control in LHCb

    CERN Document Server

    Granado Cardoso, L; Jacobsson, R

    2011-01-01

    LHCb is one of the 4 LHC experiments. In order to ensure the safety of the detector and to maximize efficiency, LHCb needs to coordinate its own operations, in particular the voltage configuration of the different subdetectors, according to the accelerator status. A control software has been developed for this purpose, based on the Finite State Machine toolkit and the SCADA system used for control throughout LHCb (and the other LHC experiments). This software permits to efficiently drive both the Low Voltage (LV) and High Voltage (HV) systems of the 10 different sub-detectors that constitute LHCb, setting each sub-system to the required voltage (easily configurable at run-time) based on the accelerator state. The control software is also responsible for monitoring the state of the Sub-detector voltages and adding it to the event data in the form of status-bits. Safe and yet flexible operation of the LHCb detector has been obtained and automatic actions, triggered by the state changes of the ...

  20. Magnetostrictive-piezoelectric magnetic sensor with current excitation

    CERN Document Server

    Prieto, J L; López, E; Sanchez, M C; Sanchez, P

    2000-01-01

    A new working configuration for magnetostrictive-piezoelectric magnetic sensors is presented. In this configuration, the excitation is caused using an electrical current flowing through the ferromagnetic sample and the induced signal is sensed in the piezoelectric support as an electrical voltage. This new idea allows a magnetic field detection without any coil and opens a possibility for a future miniaturisation of the sensor.

  1. Optimized Controller Design for a 12-Pulse Voltage Source Converter Based HVDC System

    Science.gov (United States)

    Agarwal, Ruchi; Singh, Sanjeev

    2017-08-01

    The paper proposes an optimized controller design scheme for power quality improvement in 12-pulse voltage source converter based high voltage direct current system. The proposed scheme is hybrid combination of golden section search and successive linear search method. The paper aims at reduction of current sensor and optimization of controller. The voltage and current controller parameters are selected for optimization due to its impact on power quality. The proposed algorithm for controller optimizes the objective function which is composed of current harmonic distortion, power factor, and DC voltage ripples. The detailed designs and modeling of the complete system are discussed and its simulation is carried out in MATLAB-Simulink environment. The obtained results are presented to demonstrate the effectiveness of the proposed scheme under different transient conditions such as load perturbation, non-linear load condition, voltage sag condition, and tapped load fault under one phase open condition at both points-of-common coupling.

  2. As4S4 Induced Apoptosis in HeLa Cells and Its Molecular Mechanism

    Institute of Scientific and Technical Information of China (English)

    YIN Ling; PU De-min; CHENG Yan-xiang; LIU Rong; LI Tian

    2007-01-01

    Objective: To investigate the As4S4 induced growth inhibition and apoptosis in HeLa cells and its possible relationship with cyclooxygenase-2 (COX-2). Methods: HeLa cells were treated with various concentrations (7.5, 15, 30, 60 mg/L) of As4S4 at different times (12, 24, 36, 48, 60 h). Cell growth was measured by MTT. Apoptosis was detected by double staining flow cytometry (FCM). Levels of PGE2 were measured by radioimmunoassay. The expression of COX-2 protein was examined by Western blot analysis. Results: After treated with different concentrations of As4S4, the growth of HeLa cells was suppressed significantly in a dose-and time-dependent manner. The IC50 of 24 h was 30 mg/L (P<0.01). As4S4 induced apoptosis with apoptosis rates at 8.13%-62.36% by flow cytometry (FCM) in a dose-dependent manners. The release of PGE2 was reduced in HeLa cells with the values being (70.56±2.03), (48.58±2.28), (29.25±1.57) and (18.02±1.04) respectively, significantly different compared with control group (3.15±0.01) (P<0.01). As4S4 also inhibited the activity and expression of COX-2 in a dose dependent manner and down-regulated the expression of COX-2 protein greatly. Conclusion: As4S4 could inhibit the proliferation and increase apoptosis in human HeLa cells. These effects may depend on the inhibition of the expression of COX-2 and PGE2 by As4S4.

  3. A Comparative Study of Ultra-Low Voltage Digital Circuit Design

    Directory of Open Access Journals (Sweden)

    Aaron Arthurs

    2012-07-01

    Full Text Available Ultra-low voltage digital circuit design is an active research area, especially for portable applications such as wearable electronics, intelligent remote sensors, implantable medical devices, and energy-harvesting systems. Due to their application scenarios and circuit components, two major goals for these systems are minimizing energy consumption and improving compatibility with low-voltage power supplies and analog components. The most effective solution to achieve these goals is to reduce the supply voltage, which,however, raises the issue of operability. At ultra-low supply voltages, the integrity of digital signals degrades dramatically due to the indifference between active and leakage currents. In addition, the system timing becomes more unpredictable as the impact of process and supply voltage variations being more significant at lower voltages. This paper presents a comparative study among three techniques for designing digital circuits operating at ultra-low voltages, i.e., Schmitt-triggered gate structure, delayinsensitive asynchronous logic, and Fully-Depleted Silicon-on-Insulator technology. Results show that despite the tradeoffs, all eight combinations of these techniques are viable for designing ultra-low voltage circuits. For a given application, the optimum circuit design can be selected from these combinations based on the lowest voltage, the dynamic range, the power budget, the performance requirement, and the available semiconductor process node.

  4. A Comparative Study of Ultra-Low Voltage Digital Circuit Design

    Directory of Open Access Journals (Sweden)

    Aaron Arthurs,

    2012-06-01

    Full Text Available Ultra-low voltage digital circuit design is an active research area, especially for portable applications such as wearable electronics, intelligent remote sensors, implantable medical devices, and energy-harvesting systems. Due to their application scenarios and circuit components, two major goals for these systems are minimizing energy consumption and improving compatibility with low-voltage power supplies and analog components. The most effective solution to achieve these goals is to reduce the supply voltage, which,however, raises the issue of operability. At ultra-low supply voltages, the integrity of digital signals degrades dramatically due to the indifference between active and leakage currents. In addition, the system timing becomes more unpredictable as the impact of process and supply voltage variations being more significant at lower voltages. This paper presents a comparative study among three techniques for designing digital circuits operating at ultra-low voltages, i.e., Schmitt-triggered gate structure, delay insensitive asynchronous logic, and Fully-Depleted Silicon-on-Insulator technology. Results show that despite the trade offs, all eight combinations of these techniques are viable for designing ultra-low voltage circuits. For a given application, the optimum circuit design can be selected from these combinations based on the lowest voltage, the dynamic range, the power budget, the performance requirement, and the available semiconductor process node.

  5. Development of a New Cascade Voltage-Doubler for Voltage Multiplication

    OpenAIRE

    Arash Toudeshki; Norman Mariun; Hashim Hizam; Noor Izzri Abdul Wahab

    2014-01-01

    For more than eight decades, cascade voltage-doubler circuits are used as a method to produce DC output voltage higher than the input voltage. In this paper, the topological developments of cascade voltage-doublers are reviewed. A new circuit configuration for cascade voltage-doubler is presented. This circuit can produce a higher value of the DC output voltage and better output quality compared to the conventional cascade voltage-doubler circuits, with the same number of stages.

  6. Low-Energy Real-Time OS Using Voltage Scheduling Algorithm for Variable Voltage Processors

    OpenAIRE

    Okuma, Takanori; Yasuura, Hiroto

    2001-01-01

    This paper presents a real-time OS based on $ mu $ITRON using proposed voltage scheduling algorithm for variable voltage processors which can vary supply voltage dynamically. The proposed voltage scheduling algorithms assign voltage level for each task dynamically in order to minimize energy consumption under timing constraints. Using the presented real-time OS, running tasks with low supply voltage leads to drastic energy reduction. In addition, the presented voltage scheduling algorithm is ...

  7. Simple buck/boost voltage regulator

    Science.gov (United States)

    Paulkovich, J.; Rodriguez, G. E.

    1980-01-01

    Circuit corrects low or high supply voltage, produces regulated output voltage. Circuit has fewer components because inductory/transformer combination and pulse-width modulator serve double duty. Regulator handles input voltage variation from as low as one half output voltage to as high as input transistor rating. Solar arrays, fuel cells, and thermionic generators might use this regulator.

  8. 30 CFR 18.47 - Voltage limitation.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Voltage limitation. 18.47 Section 18.47 Mineral... § 18.47 Voltage limitation. (a) A tool or switch held in the operator's hand or supported against his... particular voltage(s) are provided in the design and construction of the equipment, its wiring,...

  9. Microhotplate Temperature Sensor Calibration and BIST.

    Science.gov (United States)

    Afridi, M; Montgomery, C; Cooper-Balis, E; Semancik, S; Kreider, K G; Geist, J

    2011-01-01

    In this paper we describe a novel long-term microhotplate temperature sensor calibration technique suitable for Built-In Self Test (BIST). The microhotplate thermal resistance (thermal efficiency) and the thermal voltage from an integrated platinum-rhodium thermocouple were calibrated against a freshly calibrated four-wire polysilicon microhotplate-heater temperature sensor (heater) that is not stable over long periods of time when exposed to higher temperatures. To stress the microhotplate, its temperature was raised to around 400 °C and held there for days. The heater was then recalibrated as a temperature sensor, and microhotplate temperature measurements were made based on the fresh calibration of the heater, the first calibration of the heater, the microhotplate thermal resistance, and the thermocouple voltage. This procedure was repeated 10 times over a period of 80 days. The results show that the heater calibration drifted substantially during the period of the test while the microhotplate thermal resistance and the thermocouple-voltage remained stable to within about plus or minus 1 °C over the same period. Therefore, the combination of a microhotplate heater-temperature sensor and either the microhotplate thermal resistance or an integrated thin film platinum-rhodium thermocouple can be used to provide a stable, calibrated, microhotplate-temperature sensor, and the combination of the three sensor is suitable for implementing BIST functionality. Alternatively, if a stable microhotplate-heater temperature sensor is available, such as a properly annealed platinum heater-temperature sensor, then the thermal resistance of the microhotplate and the electrical resistance of the platinum heater will be sufficient to implement BIST. It is also shown that aluminum- and polysilicon-based temperature sensors, which are not stable enough for measuring high microhotplate temperatures (>220 °C) without impractically frequent recalibration, can be used to measure the

  10. Cavity Voltage Phase Modulation MD

    CERN Document Server

    Mastoridis, Themistoklis; Molendijk, John; Timko, Helga; CERN. Geneva. ATS Department

    2016-01-01

    The LHC RF/LLRF system is currently configured for extremely stable RF voltage to minimize transient beam loading effects. The present scheme cannot be extended beyond nominal beam current since the demanded power would exceed the peak klystron power and lead to saturation. A new scheme has therefore been proposed: for beam currents above nominal (and possibly earlier), the cavity phase modulation by the beam will not be corrected (transient beam loading), but the strong RF feedback and One-Turn Delay feedback will still be active for loop and beam stability in physics. To achieve this, the voltage set point will be adapted for each bunch. The goal of this MD was to test a new algorithm that would adjust the voltage set point to achieve the cavity phase modulation that would minimize klystron forward power.

  11. Portable High Voltage Impulse Generator

    Directory of Open Access Journals (Sweden)

    S. Gómez

    2011-07-01

    Full Text Available This paper presents a portable high voltage impulse generator which was designed and built with insulation up to 20 kV. This design was based on previous work in which simulation software for standard waves was developed. Commercial components and low-cost components were used in this work; however, these particular elements are not generally used for high voltage applications. The impulse generators used in industry and laboratories are usually expensive; they are built to withstand extra high voltage and they are big, making them impossible to transport. The proposed generator is portable, thereby allowing tests to be made on devices that cannot be moved from their location. The results obtained with the proposed impulse generator were satisfactory in terms of time and waveforms compared to other commercial impulse generators and the standard impulse wave simulator.

  12. A low voltage CMOS low drop-out voltage regulator

    Science.gov (United States)

    Bakr, Salma Ali; Abbasi, Tanvir Ahmad; Abbasi, Mohammas Suhaib; Aldessouky, Mohamed Samir; Abbasi, Mohammad Usaid

    2009-05-01

    A low voltage implementation of a CMOS Low Drop-Out voltage regulator (LDO) is presented. The requirement of low voltage devices is crucial for portable devices that require extensive computations in a low power environment. The LDO is implemented in 90nm generic CMOS technology. It generates a fixed 0.8V from a 2.5V supply which on discharging goes to 1V. The buffer stage used is unity gain configured unbuffered OpAmp with rail-to-rail swing input stage. The simulation result shows that the implemented circuit provides load regulation of 0.004%/mA and line regulation of -11.09mV/V. The LDO provides full load transient response with a settling time of 5.2μs. Further, the dropout voltage is 200mV and the quiescent current through the pass transistor (Iload=0) is 20μA. The total power consumption of this LDO (excluding bandgap reference) is only 80μW.

  13. Implementation of Dynamic Voltage Restorer for Mitigation of Voltage Sag

    Directory of Open Access Journals (Sweden)

    K.Vinod Kumar

    2013-07-01

    Full Text Available Power quality is one of major concerns in the present. It has become important, especially with the introduction of sophisticated devices, whose performance is very sensitive to the quality of power supply. The dynamic voltage restorer (DVR is one of the modern devices used in distribution systems to improve the power quality. In this paper, emergency control in distribution systems is discussed by using the proposed multifunctional DVR control strategy.Also, themultiloop controller using the Posicast and P+Resonant controllers is proposed in order to improve the transient response and eliminate the steady state error in DVR response,respectively.The proposed process is applied to some riots in load voltage effected by induction motors starting, and a three-phase short circuit fault. The three-phase short circuits, and the large induction motors are suddenly started then voltage sags areoccurred.The innovation here is that by using the Multifunctional Dynamic Voltage Restorer, improve the power quality in distribution side. Simulation results show the capability of the DVR to control the emergency conditions of the distribution systems by using MATLAB/Simulink software.

  14. The high voltage homopolar generator

    Science.gov (United States)

    Price, J. H.; Gully, J. H.; Driga, M. D.

    1986-11-01

    System and component design features of proposed high voltage homopolar generator (HVHPG) are described. The system is to have an open circuit voltage of 500 V, a peak output current of 500 kA, 3.25 MJ of stored inertial energy and possess an average magnetic-flux density of 5 T. Stator assembly components are discussed, including the stator, mount structure, hydrostatic bearings, main and motoring brushgears and rotor. Planned operational procedures such as monitoring the rotor to full speed and operation with a superconducting field coil are delineated.

  15. Chemical sensors

    Science.gov (United States)

    Lowell, J.R. Jr.; Edlund, D.J.; Friesen, D.T.; Rayfield, G.W.

    1991-07-02

    Sensors responsive to small changes in the concentration of chemical species are disclosed. The sensors comprise a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment. They are operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical response. 9 figures.

  16. Resilient architecture design for voltage variation

    CERN Document Server

    Reddi, Vijay Janapa

    2013-01-01

    Shrinking feature size and diminishing supply voltage are making circuits sensitive to supply voltage fluctuations within the microprocessor, caused by normal workload activity changes. If left unattended, voltage fluctuations can lead to timing violations or even transistor lifetime issues that degrade processor robustness. Mechanisms that learn to tolerate, avoid, and eliminate voltage fluctuations based on program and microarchitectural events can help steer the processor clear of danger, thus enabling tighter voltage margins that improve performance or lower power consumption. We describe

  17. Pathogen Sensors

    Directory of Open Access Journals (Sweden)

    Joseph Irudayaraj

    2009-10-01

    Full Text Available The development of sensors for detecting foodborne pathogens has been motivated by the need to produce safe foods and to provide better healthcare. However, in the more recent times, these needs have been expanded to encompass issues relating to biosecurity, detection of plant and soil pathogens, microbial communities, and the environment. The range of technologies that currently flood the sensor market encompass PCR and microarray-based methods, an assortment of optical sensors (including bioluminescence and fluorescence, in addition to biosensor-based approaches that include piezoelectric, potentiometric, amperometric, and conductometric sensors to name a few. More recently, nanosensors have come into limelight, as a more sensitive and portable alternative, with some commercial success. However, key issues affecting the sensor community is the lack of standardization of the testing protocols and portability, among other desirable elements, which include timeliness, cost-effectiveness, user-friendliness, sensitivity and specificity. [...

  18. Smart Sensors

    Science.gov (United States)

    Corsi, C.

    2007-01-01

    The term "Smart Sensors" refers to sensors which contain both sensing and signal processing capabilities with objectives ranging from simple viewing to sophisticated remote sensing, surveillance, search/track, weapon guidance, robotics, perceptronics and intelligence applications. Recently this approach is achieving higher goals by a new and revolutionary sensors concept which introduced inside the sensor some of the basic functions of living eyes, such as dynamic stare, non-uniformity compensation, spatial and temporal filtering. New objectives and requirements are presented for this type of new infrared smart sensor systems. This paper is concerned with the front end of FPA microbolometers processing, namely, the enhancement of target-to-noise ratio by background clutter suppression and the improvement in target detection by "smart" and pattern correlation thresholding.

  19. Low voltage electron multiplying CCD in a CMOS process

    Science.gov (United States)

    Dunford, Alice; Stefanov, Konstantin; Holland, Andrew

    2016-07-01

    Low light level and high-speed image sensors as required for space applications can suffer from a decrease in the signal to noise ratio (SNR) due to the photon-starved environment and limitations of the sensor's readout noise. The SNR can be increased by the implementation of Time Delay Integration (TDI) as it allows photoelectrons from multiple exposures to be summed in the charge domain with no added noise. Electron Multiplication (EM) can further improve the SNR and lead to an increase in device performance. However, both techniques have traditionally been confined to Charge Coupled Devices (CCD) due to the efficient charge transfer required. With the increase in demand for CMOS sensors with equivalent or superior functionality and performance, this paper presents findings from the characterisation of a low voltage EMCCD in a CMOS process using advanced design features to increase the electron multiplying gain. By using the CMOS process, it is possible to increase chip integration and functionality and achieve higher readout speeds and reduced pixel size. The presented characterisation results include analysis of the photon transfer curve, the dark current, the electron multiplying gain and analysis of the parameters' dependence on temperature and operating voltage.

  20. Regulation of Na(+) channel inactivation by the DIII and DIV voltage-sensing domains.

    Science.gov (United States)

    Hsu, Eric J; Zhu, Wandi; Schubert, Angela R; Voelker, Taylor; Varga, Zoltan; Silva, Jonathan R

    2017-03-06

    Functional eukaryotic voltage-gated Na(+) (NaV) channels comprise four domains (DI-DIV), each containing six membrane-spanning segments (S1-S6). Voltage sensing is accomplished by the first four membrane-spanning segments (S1-S4), which together form a voltage-sensing domain (VSD). A critical NaV channel gating process, inactivation, has previously been linked to activation of the VSDs in DIII and DIV. Here, we probe this interaction by using voltage-clamp fluorometry to observe VSD kinetics in the presence of mutations at locations that have been shown to impair NaV channel inactivation. These locations include the DIII-DIV linker, the DIII S4-S5 linker, and the DIV S4-S5 linker. Our results show that, within the 10-ms timeframe of fast inactivation, the DIV-VSD is the primary regulator of inactivation. However, after longer 100-ms pulses, the DIII-DIV linker slows DIII-VSD deactivation, and the rate of DIII deactivation correlates strongly with the rate of recovery from inactivation. Our results imply that, over the course of an action potential, DIV-VSDs regulate the onset of fast inactivation while DIII-VSDs determine its recovery.

  1. Design Of Piezoelectric Microcantilever Chemical Sensors In COMSOL Multiphysics Area

    OpenAIRE

    Maziar Norouzi; Alireza Kashaninia

    2009-01-01

    This paper offers an analytical modeling ofthin-filmed, multi-layer piezoelectric microcantileversthat are used as MEMS sensors. These sensors arechemical kind and use piezoelectric microcantilever.These types of microcantilevers are covered withvariety of unique probe coating. The sensor has highsensitivity with external voltage measured in mV anduses PSD1 system to indentify chemical ingredients ofmaterials. The identification of the chemical ingredientof materials is based on change in ang...

  2. Design,Fabrication and Test of a VME Pressure Sensor

    Institute of Scientific and Technical Information of China (English)

    XIAShanhong; CHENShaofeng; LIUJia

    2003-01-01

    This paper presents the design,fabrication,packaging and measurement results of a vacuum microelectronic(VME)pressure sensor.A new configuration,named "cathode-on-membrane",greatly reduces the difficulties in the packaging process and enables practical VME pressure sensors to be developed.Experimental studies and results demonstrate the characteristics of the sensor output current variation with applied pressure under different working voltages.

  3. Fine-tuning of voltage sensitivity of the Kv1.2 potassium channel by interhelix loop dynamics.

    Science.gov (United States)

    Sand, Rheanna; Sharmin, Nazlee; Morgan, Carla; Gallin, Warren J

    2013-04-01

    Many proteins function by changing conformation in response to ligand binding or changes in other factors in their environment. Any change in the sequence of a protein, for example during evolution, which alters the relative free energies of the different functional conformations changes the conditions under which the protein will function. Voltage-gated ion channels are membrane proteins that open and close an ion-selective pore in response to changes in transmembrane voltage. The charged S4 transmembrane helix transduces changes in transmembrane voltage into a change in protein internal energy by interacting with the rest of the channel protein through a combination of non-covalent interactions between adjacent helices and covalent interactions along the peptide backbone. However, the structural basis for the wide variation in the V50 value between different voltage-gated potassium channels is not well defined. To test the role of the loop linking the S3 helix and the S4 helix in voltage sensitivity, we have constructed a set of mutants of the rat Kv1.2 channel that vary solely in the length and composition of the extracellular loop that connects S4 to S3. We evaluated the effect of these different loop substitutions on the voltage sensitivity of the channel and compared these experimental results with molecular dynamics simulations of the loop structures. Here, we show that this loop has a significant role in setting the precise V50 of activation in Kv1 family channels.

  4. Non-contiguous finished genome sequence of plant-growth promoting Serratia proteamaculans S4.

    Science.gov (United States)

    Neupane, Saraswoti; Goodwin, Lynne A; Högberg, Nils; Kyrpides, Nikos C; Alström, Sadhna; Bruce, David; Quintana, Beverly; Munk, Christine; Daligault, Hajnalka; Teshima, Hazuki; Davenport, Karen; Reitenga, Krista; Green, Lance; Chain, Patrick; Erkkila, Tracy; Gu, Wei; Zhang, Xiaojing; Xu, Yan; Kunde, Yulia; Chertkov, Olga; Han, James; Han, Cliff; Detter, John C; Ivanova, Natalia; Pati, Amrita; Chen, Amy; Szeto, Ernest; Mavromatis, Kostas; Huntemann, Marcel; Nolan, Matt; Pitluck, Sam; Deshpande, Shweta; Markowitz, Victor; Pagani, Ioanna; Klenk, Hans-Peter; Woyke, Tanja; Finlay, Roger D

    2013-07-30

    Serratia proteamaculans S4 (previously Serratia sp. S4), isolated from the rhizosphere of wild Equisetum sp., has the ability to stimulate plant growth and to suppress the growth of several soil-borne fungal pathogens of economically important crops. Here we present the non-contiguous, finished genome sequence of S. proteamaculans S4, which consists of a 5,324,944 bp circular chromosome and a 129,797 bp circular plasmid. The chromosome contains 5,008 predicted genes while the plasmid comprises 134 predicted genes. In total, 4,993 genes are assigned as protein-coding genes. The genome consists of 22 rRNA genes, 82 tRNA genes and 58 pseudogenes. This genome is a part of the project "Genomics of four rapeseed plant growth-promoting bacteria with antagonistic effect on plant pathogens" awarded through the 2010 DOE-JGI's Community Sequencing Program.

  5. Potential role of voltage-sensing phosphatases in regulation of cell structure through the production of PI(3,4)P2.

    Science.gov (United States)

    Yamaguchi, Shinji; Kurokawa, Tatsuki; Taira, Ikuko; Aoki, Naoya; Sakata, Souhei; Okamura, Yasushi; Homma, Koichi J

    2014-04-01

    Voltage-sensing phosphatase, VSP, consists of the transmembrane domain, operating as the voltage sensor, and the cytoplasmic domain with phosphoinositide-phosphatase activities. The voltage sensor tightly couples with the cytoplasmic phosphatase and membrane depolarization induces dephosphorylation of several species of phosphoinositides. VSP gene is conserved from urochordate to human. There are some diversities among VSP ortholog proteins; range of voltage of voltage sensor motions as well as substrate selectivity. In contrast with recent understandings of biophysical mechanisms of VSPs, little is known about its physiological roles. Here we report that chick ortholog of VSP (designated as Gg-VSP) induces morphological feature of cell process outgrowths with round cell body in DF-1 fibroblasts upon its forced expression. Expression of the voltage sensor mutant, Gg-VSPR153Q with shifted voltage dependence to a lower voltage led to more frequent changes of cell morphology than the wild-type protein. Coexpression of PTEN that dephosphorylates PI(3,4)P2 suppressed this effect by Gg-VSP, indicating that the increase of PI(3,4)P2 leads to changes of cell shape. In addition, visualization of PI(3,4)P2 with the fluorescent protein fused with the TAPP1-derived pleckstrin homology (PH) domain suggested that Gg-VSP influenced the distribution of PI(3,4)P2 . These findings raise a possibility that one of the VSP's functions could be to regulate cell morphology through voltage-sensitive tuning of phosphoinositide profile.

  6. A VDF/TrFE copolymer on silicon pyroelectric sensor: design considerations and experiments

    NARCIS (Netherlands)

    Setiadi, D.; Regtien, P.P.L.

    1995-01-01

    For an optimal design of a VDF/TrFE (vinylidene fluoride trifluoroethylene) copolymer-on-silicon pyroelectric sensor, the one-dimensional diffusion equation is solved for the pyroelectric multilayer structure. Output current and voltage of the sensor are calculated. Improvement of the sensor can be

  7. Multimeric nature of voltage-gated proton channels.

    Science.gov (United States)

    Koch, Hans P; Kurokawa, Tatsuki; Okochi, Yoshifumi; Sasaki, Mari; Okamura, Yasushi; Larsson, H Peter

    2008-07-01

    Voltage-gated potassium channels are comprised of four subunits, and each subunit has a pore domain and a voltage-sensing domain (VSD). The four pore domains assemble to form one single central pore, and the four individual VSDs control the gate of the pore. Recently, a family of voltage-gated proton channels, such as H(V) or voltage sensor only protein (VSOP), was discovered that contain a single VSD but no pore domain. It has been assumed that VSOP channels are monomeric and contain a single VSD that functions as both the VSD and the pore domain. It remains unclear, however, how a protein that contains only a VSD and no pore domain can conduct ions. Using fluorescence measurements and immunoprecipitation techniques, we show here that VSOP channels are expressed as multimeric channels. Further, FRET experiments on constructs with covalently linked subunits show that VSOP channels are dimers. Truncation of the cytoplasmic regions of VSOP reduced the dimerization, suggesting that the dimerization is caused mainly by cytoplasmic protein-protein interactions. However, these N terminus- and C terminus-deleted channels displayed large proton currents. Therefore, we conclude that even though VSOP channels are expressed mainly as dimers in the cell membrane, single VSOP subunits could function independently as proton channels.

  8. Approaching Minimal Flavour Violation from an S4 x SU(5) SUSY GUT

    CERN Document Server

    Dimou, Maria; Luhn, Christoph

    2015-01-01

    We show how approximate Minimal Flavour Violation (MFV) can emerge from an SU(5) Supersymmetric Grand Unified Theory (SUSY GUT) supplemented by an S4 x U(1) family symmetry, which provides a good description of all quark and lepton (including neutrino) masses, mixings and CP violation. Assuming a SUSY breaking mechanism which respects the family symmetry, we calculate in full explicit detail the low energy mass insertion parameters in the super-CKM basis, including the effects of canonical normalisation and renormalisation group running. We find that the very simple family symmetry S4 x U(1) is sufficient to approximately reproduce the effects of low energy MFV.

  9. VOLTAGE REGULATORS OF SYNCHRONOUS GENERATORS

    Directory of Open Access Journals (Sweden)

    Grigorash O. V.

    2015-06-01

    Full Text Available Synchronous generators are the primary source of electrical power autonomous electrosupply systems, including backup systems. They are also used in a structure of rotating electricity converters and are widely used in renewable energy as part of wind power plants of small, mini and micro hydroelectric plants. Increasing the speed and the accuracy of the system of the voltage regulation of synchronous generators is possible due to the development of combined systems containing more stabilizers. The article illustrates the functional schemes of circuit voltage stabilizers and frequency synchronous generators (with electromagnetic excitation and permanent magnet excitation and describes the features of their work, including two and three-aggregate rotating converters of electricity used in uninterruptible power supply systems. To improve the technical characteristics of the system of stabilization we have proposed functional solutions for stabilizers of synchronous generators made on the base of direct frequency converters and using a transformer with a rotating magnetic field. To improve the reliability of and to improve the operational characteristics of the autonomous independent sources of electricity we suggest creating the main functional blocks and the elements of the stabilization system in a modular way. The functional circuit solutions of voltage regulators of synchronous generators and the characteristics of their work considered in the article, are able to improve the efficiency of pre-design work in the development of new technical solutions for stabilizing the voltage and the frequency in synchronous generators of electrosupply autonomous systems

  10. Frequency-controlled voltage regulator

    Science.gov (United States)

    Mclyman, W. T.

    1980-01-01

    Converting input ac to higher frequency reduce size and weight and makes possible unique kind of regulation. Since conversion frequency is above range of human hearing, supply generated on audible noise. It also exploits highfrequency conversion features to regulate its output voltage in novel way. Circuit is inherently short-circuit proof.

  11. High voltage magnetic pulse generation using capacitor discharge technique

    Directory of Open Access Journals (Sweden)

    M. Rezal

    2014-12-01

    Full Text Available A high voltage magnetic pulse is designed by applying an electrical pulse to the coil. Capacitor banks are developed to generate the pulse current. Switching circuit consisting of Double Pole Double Throw (DPDT switches, thyristor, and triggering circuit is developed and tested. The coil current is measured using a Hall-effect current sensor. The magnetic pulse generated is measured and tabulated in a graph. Simulation using Finite Element Method Magnetics (FEMM is done to compare the results obtained between experiment and simulation. Results show that increasing the capacitance of the capacitor bank will increase the output voltage. This technology can be applied to areas such as medical equipment, measurement instrument, and military equipment.

  12. Voltage-gated Proton Channels

    Science.gov (United States)

    DeCoursey, Thomas E.

    2014-01-01

    Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance ~103 smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. PMID:23798303

  13. A Micro-Fabricated Force Sensor Using an All Thin Film Piezoelectric Active Sensor

    Directory of Open Access Journals (Sweden)

    Junwoo Lee

    2014-11-01

    Full Text Available The ability to measure pressure and force is essential in biomedical applications such as minimally invasive surgery (MIS and palpation for detecting cancer cysts. Here, we report a force sensor for measuring a shear and normal force by combining an arrayed piezoelectric sensors layer with a precut glass top plate connected by four stress concentrating legs. We designed and fabricated a thin film piezoelectric force sensor and proposed an enhanced sensing tool to be used for analyzing gentle touches without the external voltage source used in FET sensors. Both the linear sensor response from 3 kPa to 30 kPa and the exact signal responses from the moving direction illustrate the strong feasibility of the described thin film miniaturized piezoelectric force sensor.

  14. Aurelia aurita bio-inspired tilt sensor

    Science.gov (United States)

    Smith, Colin; Villanueva, Alex; Priya, Shashank

    2012-10-01

    The quickly expanding field of mobile robots, unmanned underwater vehicles, and micro-air vehicles urgently needs a cheap and effective means for measuring vehicle inclination. Commonly, tilt or inclination has been mathematically derived from accelerometers; however, there is inherent error in any indirect measurement. This paper reports a bio-inspired tilt sensor that mimics the natural balance organ of jellyfish, called the ‘statocyst’. Biological statocysts from the species Aurelia aurita were characterized by scanning electron microscopy to investigate the morphology and size of the natural sensor. An artificial tilt sensor was then developed by using printed electronics that incorporates a novel voltage divider concept in conjunction with small surface mount devices. This sensor was found to have minimum sensitivity of 4.21° with a standard deviation of 1.77°. These results open the possibility of developing elegant tilt sensor architecture for both air and water based platforms.

  15. Biomimetic actuator and sensor for robot hand

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Baekchul; Chung, Jinah; Cho, Hanjoung; Shin, Seunghoon; Lee, Hyoungsuk; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, Jachoon [Sungkyunkwan Univ., Seoul (Korea, Republic of)

    2012-12-15

    To manufacture a robot hand that essentially mimics the functions of a human hand, it is necessary to develop flexible actuators and sensors. In this study, we propose the design, manufacture, and performance verification of flexible actuators and sensors based on Electro Active Polymer (EAP). EAP is fabricated as a type of film, and it moves with changes in the voltage because of contraction and expansion in the polymer film. Furthermore, if a force is applied to an EAP film, its thickness and effective area change, and therefore, the capacitance also changes. By using this mechanism, we produce capacitive actuators and sensors. In this study, we propose an EAP based capacitive sensor and evaluate its use as a robot hand sensor.

  16. Automotive sensors

    Science.gov (United States)

    Marek, Jiri; Illing, Matthias

    2003-01-01

    Sensors are an essential component of most electronic systems in the car. They deliver input parameters for comfort features, engine and emission control as well as for the active and passive safety systems. New technologies such as silicon micromachining play an important role for the introduction of these sensors in all vehicle classes. The importance and use of these sensor technologies in today"s automotive applications will be shown in this article. Finally an outlook on important current developments and new functions in the car will be given.

  17. Piezoceramic Sensors

    CERN Document Server

    Sharapov, Valeriy

    2011-01-01

    This book presents the latest and complete information about various types of piezosensors. A sensor is a converter of the measured physical size to an electric signal. Piezoelectric transducers and sensors are based on piezoelectric effects. They have proven to be versatile tools for the measurement of various processes. They are used for quality assurance, process control and for research and development in many different industries. In each area of application specific requirements to the parameters of transducers and sensors are developed. This book presents the fundamentals, technical des

  18. Numerical and experimental characterizations of low frequency MEMS AE sensors

    Science.gov (United States)

    Saboonchi, Hossain; Ozevin, Didem

    2013-04-01

    In this paper, new MEMS Acoustic Emission (AE) sensors are introduced. The transduction principle of the sensors is capacitance due to gap change. The sensors are numerically modeled using COMSOL Multiphysics software in order to estimate the resonant frequencies and capacitance values, and manufactured using MetalMUMPS process. The process includes thick metal layer (20 μm) made of nickel for freely vibration layer and polysilicon layer as the stationary layer. The metal layer provides a relatively heavy mass so that the spring constant can be designed high for low frequency sensor designs in order to increase the collapse voltage level (proportional to the stiffness), which increases the sensor sensitivity. An insulator layer is deposited between stationary layer and freely vibration layer, which significantly reduces the potential of stiction as a failure mode. As conventional AE sensors made of piezoelectric materials cannot be designed for low frequencies (vacuum packaging. The MEMS sensor responses are compared with similar frequency piezoelectric AE sensors.

  19. Voltage-gated K+ channels contain multiple intersubunit association sites.

    Science.gov (United States)

    Tu, L; Santarelli, V; Sheng, Z; Skach, W; Pain, D; Deutsch, C

    1996-08-02

    A domain in the cytoplasmic NH2 terminus of voltage-gated K+ channels supervises the proper assembly of specific tetrameric channels (Li, M., Jan, J. M., and Jan, L. Y.(1992) Science 257, 1225-1230; Shen, N. V., Chen X., Boyer, M. M., and Pfaffinger, P. (1993) Neuron 11, 67-76). It is referred to as a first tetramerization domain, or T1 (Shen, N. V., Chen X., Boyer, M. M., and Pfaffinger, P.(1993) Neuron 11, 67-76). However, a deletion mutant of Kv1.3 that lacks the first 141 amino acids, Kv1.3 (T1(-)) forms functional channels, suggesting that additional association sites in the central core of Kv1.3 mediate oligomerization. To characterize these sites, we have tested the abilities of cRNA Kv1.3 (T1(-)) fragments co-injected with Kv1.3 (T1(-)) to suppress current in Xenopus oocytes. The fragments include portions of the six putative transmembrane segments, S1 through S6, specifically: S1, S1-S2, S1-S2-S3, S2-S3, S2-S3-S4, S3-S4, S3-S4-S5, S2 through COOH, S3 through COOH, S4 through COOH, and S5-S6-COOH. Electrophysiologic experiments show that the fragments S1-S2-S3, S3-S4-S5, S2 through COOH, and S3 through COOH strongly suppress Kv1.3 (T1(-)) current, while others do not. Suppression of expressed current is due to specific effects of the translated peptide Kv1.3 fragments, as validated by in vivo immunoprecipitation studies of a strong suppressor and a nonsuppressor. Pulse-chase experiments indicate that translation of truncated peptide fragments neither prevents translation of Kv1.3 (T1(-)) nor increases its rate of degradation. Co-immunoprecipitation experiments suggest that suppression involves direct association of a peptide fragment with Kv1.3 (T1(-)). Fragments that strongly suppress Kv1.3 (T1(-)) also suppress an analogous NH2-terminal deletion mutant of Kv2.1 (Kv2.1 (DeltaN139)), an isoform belonging to a different subfamily. Our results indicate that sites in the central core of Kv1.3 facilitate intersubunit association and that there are suppression

  20. Chemical Sensors Based on Piezoresistive Cantilever Array

    Institute of Scientific and Technical Information of China (English)

    于晓梅; 张大成; 王丛舜; 杜先锋; 王小宝; 阮勇

    2003-01-01

    U-shaped and rectangle piezoresistive cantilever arrays have been designed with the analysing results of stress,noise and sensitivity of the cantilevers. Based on silicon micromachining technology, the piezoresistive cantilevers were fabricated by using polysilicon as the piezoresistive materials. With the measurement results of noise and sensitivity, the Hooge factor is calculated to be 3 × 10-3, the gauge factor is 27, and the minimum detectable deflection of piezoresistive cantilevers are calculated to be 1.0nm for rectangle cantilever and 0.5 nm for the Ushaped cantilever at a 6 V bias voltage and a 1000 Hz measurement bandwidth. Using polymer-coated cantilevers as individual sensors, their responses to water vapour and ammonia were tested by measuring their output voltage signals. The measured results show that the sensor sensitivity to ammonia can reach a few ppm and the sensor responses are quick.

  1. Archaerhodopsin variants with enhanced voltage-sensitive fluorescence in mammalian and Caenorhabditis elegans neurons.

    Science.gov (United States)

    Flytzanis, Nicholas C; Bedbrook, Claire N; Chiu, Hui; Engqvist, Martin K M; Xiao, Cheng; Chan, Ken Y; Sternberg, Paul W; Arnold, Frances H; Gradinaru, Viviana

    2014-09-15

    Probing the neural circuit dynamics underlying behaviour would benefit greatly from improved genetically encoded voltage indicators. The proton pump Archaerhodopsin-3 (Arch), an optogenetic tool commonly used for neuronal inhibition, has been shown to emit voltage-sensitive fluorescence. Here we report two Arch variants with enhanced radiance (Archers) that in response to 655 nm light have 3-5 times increased fluorescence and 55-99 times reduced photocurrents compared with Arch WT. The most fluorescent variant, Archer1, has 25-40% fluorescence change in response to action potentials while using 9 times lower light intensity compared with other Arch-based voltage sensors. Archer1 is capable of wavelength-specific functionality as a voltage sensor under red light and as an inhibitory actuator under green light. As a proof-of-concept for the application of Arch-based sensors in vivo, we show fluorescence voltage sensing in behaving Caenorhabditis elegans. Archer1's characteristics contribute to the goal of all-optical detection and modulation of activity in neuronal networks in vivo.

  2. Archaerhodopsin Variants with Enhanced Voltage Sensitive Fluorescence in Mammalian and Caenorhabditis elegans Neurons

    Science.gov (United States)

    Flytzanis, Nicholas C.; Bedbrook, Claire N.; Chiu, Hui; Engqvist, Martin K. M.; Xiao, Cheng; Chan, Ken Y.; Sternberg, Paul W.; Arnold, Frances H.; Gradinaru, Viviana

    2014-01-01

    Probing the neural circuit dynamics underlying behavior would benefit greatly from improved genetically encoded voltage indicators. The proton pump Archaerhodopsin-3 (Arch), an optogenetic tool commonly used for neuronal inhibition, has been shown to emit voltage sensitive fluorescence. Here we report two Arch variants that in response to 655 nm light have 3–5 times increased fluorescence and 55–99 times reduced photocurrents compared to Arch WT. The most fluorescent variant, Archer1, has 25–40% fluorescence change in response to action potentials while using 9 times lower light intensity compared to other Arch-based voltage sensors. Archer1 is capable of wavelength specific functionality as a voltage sensor under red-light and as an inhibitory actuator under green-light. As a proof-of-concept for the application of Arch-based sensors in vivo, we show fluorescence voltage sensing in behaving C. elegans. Archer1’s characteristics contribute to the goal of all-optical detection and modulation of activity in neuronal networks in vivo. PMID:25222271

  3. Caution Is Required in Interpretation of Mutations in the Voltage Sensing Domain of Voltage Gated Channels as Evidence for Gating Mechanisms

    Directory of Open Access Journals (Sweden)

    Alisher M. Kariev

    2015-01-01

    Full Text Available The gating mechanism of voltage sensitive ion channels is generally considered to be the motion of the S4 transmembrane segment of the voltage sensing domains (VSD. The primary supporting evidence came from R→C mutations on the S4 transmembrane segment of the VSD, followed by reaction with a methanethiosulfonate (MTS reagent. The cys side chain is –SH (reactive form –S−; the arginine side chain is much larger, leaving space big enough to accommodate the MTS sulfonate head group. The cavity created by the mutation has space for up to seven more water molecules than were present in wild type, which could be displaced irreversibly by the MTS reagent. Our quantum calculations show there is major reorientation of three aromatic residues that face into the cavity in response to proton displacement within the VSD. Two phenylalanines reorient sufficiently to shield/unshield the cysteine from the intracellular and extracellular ends, depending on the proton positions, and a tyrosine forms a hydrogen bond to the cysteine sulfur with its side chain –OH. These could produce the results of the experiments that have been interpreted as evidence for physical motion of the S4 segment, without physical motion of the S4 backbone. The computations strongly suggest that the interpretation of cysteine substitution reaction experiments be re-examined in the light of these considerations.

  4. The Extremes in Intra-Night Blazar Variability: The S4 0954+65 Case

    CERN Document Server

    Bachev, Rumen; Semkov, Evgeni; Dimitrova, Rosa Victoria Muñoz; Latev, Georgi; Spassov, Borislav; Petrov, Blagovest

    2016-01-01

    We present results of optical observations of the extremely violently variable blazar S4 0954+65 on intra-night time scales. The object showed flux changes of up to 100% within a few hours. Time delays between optical bands, color changes and "rms-flux" relations are investigated and the results are discussed in terms of existing models of blazar variability.

  5. Transsacral S2-S4 nerve block for vaginal pain due to pudendal neuralgia.

    Science.gov (United States)

    Cok, Oya Yalcin; Eker, H Evren; Cok, Tayfun; Akin, Sule; Aribogan, Anis; Arslan, Gulnaz

    2011-01-01

    Pudendal neuralgia is a type of neuropathic pain experienced predominantly while sitting, and causes a substantial decrease in quality of life in affected patients. Pudendal nerve block is a diagnostic and therapeutic option for pudendal neuralgia. Transsacral block at S2 through S4 results in pudendal nerve block, which is an option for successful relief of pain due to pudendal nerve injury. Herein is reported blockade of S2 through S4 using lidocaine and methylprednisolone for successful treatment of pudendal neuralgia in 2 patients with severe chronic vaginal pain. The patients, aged 44 and 58 years, respectively, were referred from the Gynecology Department to the pain clinic because of burning, stabbing, electric shock-like, unilateral pain localized to the left portion of the vagina and extending to the perineum. Their initial pain scores were 9 and 10, respectively, on a numeric rating scale. Both patients refused pudendal nerve block using classical techniques. Therefore, diagnostic transsacral S2-S4 nerve block was performed using lidocaine 1%, and was repeated using lidocaine 1% and methylprednisolone 80 mg after confirming block efficiency as demonstrated by an immediate decrease in pain scores. After 1 month, pain scores were 1 and 0, respectively, and both patients were free of pain at 6-month follow up. It is suggested that blockade of S2 through S4 using lidocaine and methylprednisolone is an effective treatment option in patients with chronic pudendal neuralgia when traditional pudendal nerve block is not applicable.

  6. Classical strings in $AdS_4\\times\\mathbb{CP}^3$ with three angular momenta

    CERN Document Server

    Giardino, Sergio

    2011-01-01

    In this paper, rotating strings in three directions of $AdS_4 \\times \\mathbb{CP}^3$ geometry are studied; its divergent energy limit, and conserved charges are also determined. An interpretation of these configurations as either giant magnons or spiky strings are discussed.

  7. Role of the S4-S5 linker in CNG channel activation.

    Science.gov (United States)

    Kusch, Jana; Zimmer, Thomas; Holschuh, Jascha; Biskup, Christoph; Schulz, Eckhard; Nache, Vasilica; Benndorf, Klaus

    2010-10-20

    Cyclic nucleotide-gated (CNG) channels mediate sensory signal transduction in retinal and olfactory cells. The channels are activated by the binding of cyclic nucleotides to a cyclic nucleotide-binding domain (CNBD) in the C-terminus that is located at the intracellular side. The molecular events translating the ligand binding to the pore opening are still unknown. We investigated the role of the S4-S5 linker in the activation process by quantifying its interaction with other intracellular regions. To this end, we constructed chimeric channels in which the N-terminus, the S4-S5 linker, the C-linker, and the CNBD of the retinal CNGA1 subunit were systematically replaced by the respective regions of the olfactory CNGA2 subunit. Macroscopic concentration-response relations were analyzed, yielding the apparent affinity to cGMP and the Hill coefficient. The degree of functional coupling of intracellular regions in the activation gating was determined by thermodynamic double-mutant cycle analysis. We observed that all four intracellular regions, including the relatively short S4-S5 linker, are involved in controlling the apparent affinity of the channel to cGMP and, moreover, in determining the degree of cooperativity between the subunits, as derived from the Hill coefficient. The interaction energies reveal an interaction of the S4-S5 linker with both the N-terminus and the C-linker, but no interaction with the CNBD.

  8. Phase transitions of magnetic AdS4 black holes with scalar hair

    NARCIS (Netherlands)

    Hristov, K.; Toldo, C.; Vandoren, S.

    2013-01-01

    We determine the thermodynamic properties of a class of spherically symmetric and static black holes in AdS4 with magnetic charges and scalar hair. These black holes are solutions in four-dimensional N=2 gauged supergravity that can arise from 11-dimensional supergravity compactified on S7. At zero

  9. Globular Cluster Populations: First Results from S$^4$G Early-Type Galaxies

    CERN Document Server

    Zaritsky, Dennis; Athanassoula, E; Bosma, Albert; Comerón, Sébastien; Elmegreen, Bruce G; Erroz-Ferrer, Santiago; Gadotti, Dimitri A; Hinz, Joannah L; Ho, Luis C; Holwerda, Benne; Knapen, Johan H; Laine, Jarkko; Laurikainen, Eija; Muñoz-Mateos, Juan Carlos; Salo, Heikki; Sheth, Kartik

    2014-01-01

    Using 3.6$\\mu$m images of 97 early-type galaxies, we develop and verify methodology to measure globular cluster populations from the S$^4$G survey images. We find that 1) the ratio, T$_{\\rm N}$, of the number of clusters, N$_{\\rm CL}$, to parent galaxy stellar mass, M$_*$, rises weakly with M$_*$ for early-type galaxies with M$_* > 10^{10}$ M$_\\odot$ when we calculate galaxy masses using a universal stellar initial mass function (IMF), but that the dependence of T$_{\\rm N}$ on M$_*$ is removed entirely once we correct for the recently uncovered systematic variation of IMF with M$_*$, and 2) for M$_* 10^{10}$ M$_\\odot$ and can be as large as $\\sim 0.02$ for less massive galaxies. These are the first results from the S$^4$G sample of galaxies, and will be enhanced by the sample of early-type galaxies now being added to S$^4$G and complemented by the study of later type galaxies within S$^4$G.

  10. F-string Solution in AdS4 X CP3 PP-wave Background

    CERN Document Server

    Banerjee, Gourav

    2016-01-01

    We present supergravity solution for F-string in pp wave background obtained from AdS4 X CP3 with zero flat directions.The classical solution is shown to break all space-time supersymmetries. We explicitly write down the standard as well as supernumerary Killing spinors both for the background and F-string solution.

  11. Hydrogen Evolution on Supported Incomplete Cubane-type [Mo3S4](4+) Electrocatalysts

    DEFF Research Database (Denmark)

    Jaramillo, Thomas; Bonde, Jacob Lindner; Zhang, Jingdong

    2008-01-01

    Electrocatalytic properties of biomimetic supported incomplete cubane-type [Mo3S4](4+) clusters are investigated. The activity toward the hydrogen evolution reaction (HER) is evaluated on both a high surface area gas diffusion electrode in a membrane electrode assembly and on highly orientated...

  12. Structural and electronic properties of Y2CrS4 from first-principles study

    Science.gov (United States)

    Wang, B.-T.; Yin, W.; Li, W.-D.; Wang, F.

    2011-04-01

    We systematically study the structural, electronic, and magnetic properties of chromium sulfide Y2CrS4 by using density-functional theory. We find that antiferromagnetic order is more energetically favorable than ferromagnetic state and near the Fermi level the main occupation is from Cr 3 d states.

  13. High-Purity Fe3S4 Greigite Microcrystals for Magnetic and Electrochemical Performance

    NARCIS (Netherlands)

    Li, Guowei; Zhang, Baomin; Yu, Feng; Novakova, Alla A.; Krivenkov, Maxim S.; Kiseleva, Tatiana Y.; Chang, Liao; Rao, Jiancun; Polyakov, Alexey O.; Blake, Graeme R.; de Groot, Robert A.; Palstra, Thomas T. M.

    2014-01-01

    High-purity Fe3S4 (greigite) microcrystals with octahedral shape were synthesized via a simple hydrothermal method using a surfactant. The as-prepared samples have the inverse spinel structure with high crystallinity. The saturation magnetization (M-s) reaches 3.74 mu(B) at 5 K and 3.51 mu(B) at roo

  14. Magnetic charges in the AdS(4) superalgebra osp(4 vertical bar 2)

    NARCIS (Netherlands)

    Dibitetto, Giuseppe; Klemm, Dietmar

    2010-01-01

    We discuss the issue of how to include magnetic charges in the AdS(4) superalgebra osp(4 vertical bar 2). It is shown that the usual way of introducing a pseudoscalar central charge on the right hand side of the basic anticommutator does not work, because this breaks SO(2, 3) covariance. We propose

  15. Ionic liquid-modulated synthesis of ferrimagnetic Fe(3)S(4) hierarchical superstructures.

    Science.gov (United States)

    Ma, Jianmin; Chang, Liao; Lian, Jiabiao; Huang, Zheng; Duan, Xiaochuan; Liu, Xiaodi; Peng, Peng; Kim, Tongil; Liu, Zhifang; Zheng, Wenjun

    2010-07-21

    Ferrimagnetic Fe(3)S(4) nanowalls and triple hierarchical microspheres have been fabricated via an ionic liquid-modulated solution-phase process, respectively. Magnetic hysteresis measurements demonstrate that their morphology-dependent magnetic properties might be originated from their unique nanostructures.

  16. Bimaximal neutrino mixing and weak complementarity with S4 discrete symmetry

    CERN Document Server

    Merlo, Luca

    2009-01-01

    The neutrino oscillation data are well explained by the tri-bimaximal pattern. Recently a paper appeared showing that also the bimaximal pattern could be a very good starting point in order to describe the lepton mixing. In this paper I review both the flavour structures and then I present an explicit model based on the discrete symmetry group S4.

  17. Tri-bimaximal Mixing and Cabibbo Angle in S4 Flavor Model with SUSY

    CERN Document Server

    Ishimori, Hajime; Shimizu, Yusuke; Tanimoto, Morimitsu

    2010-01-01

    We present a flavor model of quarks and leptons with the non-Abelian discrete symmetry S_4 in the framework of the SU(5) SUSY GUT. Three generations of $\\bar 5$-plets in SU(5) are assigned to ${\\bf 3}$ of $S_4$ while the first and second generations of 10-plets in SU(5) are assigned to ${\\bf 2}$ of $S_4$, and the third generation of 10-plet is assigned to ${\\bf 1}$ of $S_4$. Right-handed neutrinos are also assigned to ${\\bf 2}$ for the first and second generations and ${\\bf 1}'$ for the third generation, respectively. We predict the Cabibbo angle as well as the tri-bimaximal mixing of neutrino flavors. We also predict the non-vanishing $U_{e3}$ of the neutrino flavor mixing due to higher dimensional mass operators. Our predicted CKM mixing angles and the CP violation are consistent with experimental values. We also study SUSY breaking terms in the slepton sector. Our model leads to smaller values of flavor changing neutral currents than the present experimental bounds.

  18. Computational studies of modified [Fe3S4] clusters: Why iron is optimal

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta

    2008-01-01

    This work reports density functional computations of metal-substituted models of biological [Fe3S4] clusters in oxidation states [MFe2S4]+/0/−1 (M = Mn, Fe, Co, Ni, Cu, Zn, and Mo). Geometry optimization with a dielectric screening model is shown to provide a substantial improvement in structure......, compared to earlier used standard procedures. The error for average Fe–S bonds decreased from 0.038 Å to 0.016 Å with this procedure. Four density functionals were compared, B3LYP, BP86, TPSS, and TPSSh. B3LYP and to a lesser extent TPSSh energies were inconsistent with experiment for the oxidized [Fe3S4......]+ cluster. BP86 (and to a slightly lesser extent TPSS) was within expected theoretical and experimental uncertainties for all oxidation states, the only qualitative error being 5 kJ/mol in favor of the MS = 3/2 configuration for the [Fe3S4]+ cluster, so BP86 was used for quantitative results. Computed...

  19. Mutations at opposite ends of the DIII/S4-S5 linker of sodium channel NaV1.7 produce distinct pain disorders

    Directory of Open Access Journals (Sweden)

    Tyrrell Lynda

    2010-04-01

    Full Text Available Abstract Background Two groups of gain-of-function mutations in sodium channel NaV1.7, which are expressed in dorsal root ganglion (DRG neurons, produce two clinically-distinct pain syndromes - inherited erythromelalgia (IEM and paroxysmal extreme pain disorder (PEPD. IEM is characterized by intermittent burning pain and skin redness in the feet or hands, triggered by warmth or mild exercise, while PEPD is characterized by episodes of rectal, ocular and mandibular pain accompanied with skin flushing, triggered by bowel movement and perianal stimulation. Most of the IEM mutations are located within channel domains I and II, while most of the PEPD mutations are located within domains III and IV. The structural dichotomy parallels the biophysical effects of the two types of mutations, with IEM mutations shifting voltage-dependence of NaV1.7 activation in a hyperpolarized direction, and PEPD mutations shifting fast-inactivation of NaV1.7 in a depolarized direction. While four IEM and four PEPD mutations are located within cytoplasmic linkers joining segments 4 and 5 (S4-S5 linkers in the different domains (IEM: domains I and II; PEPD: domains III and IV, no S4-S5 linker has been reported to house both IEM and PEPD mutations thus far. Results We have identified a new IEM mutation P1308L within the C-terminus of the DIII/S4-S5 linker of NaV1.7, ten amino acids from a known PEPD mutation V1298F which is located within the N-terminus of this linker. We used voltage-clamp to compare the biophysical properties of the two mutant channels and current-clamp to study their effects on DRG neuron excitability. We confirm that P1308L and V1298F behave as prototypical IEM and PEPD mutations, respectively. We also show that DRG neurons expressing either P1308L or V1298F become hyperexcitable, compared to DRG neurons expressing wild-type channels. Conclusions Our results provide evidence for differential roles of the DIII/S4-S5 linker N- and C-termini in channel

  20. Automatic Distance Monitoring System of Contact Connections in High Voltage Equipment of Electric Power Lines

    Directory of Open Access Journals (Sweden)

    M. Diachenko

    2013-01-01

    Full Text Available The developed automatic distance monitoring system of contact connections in high voltage equipment is based on technology of sensor circuits. The paper shows application of control methodology for contact connections in accordance with time rate of conductor temperature changes and contact connection and also direct measurement of transient resistance.

  1. Simulation Test System of Non-Contact D-dot Voltage Transformer

    Science.gov (United States)

    Yang, Jie; Wang, Jingang; Luo, Ruixi; Gao, Can; Songnong, Li; Kongjun, Zhou

    2016-04-01

    The development trend of future voltage transformer in smart grid is non-contact measurement, miniaturization and intellectualization. This paper proposes one simulation test system of non-contact D-dot transformer for voltage measurement. This simulation test system consists of D-dot transformer, signal processing circuit and ground PC port. D-dot transformer realizes the indirect voltage measurement by measuring the change rate of electric displacement vector, a non-contact means (He et al. 2004, Principles and experiments of voltage transformer based on self-integrating D-dot probe. Proc CSEE 2014;15:2445-51). Specific to the characteristics of D-dot transformer signals, signal processing circuits with strong resistance to interference and distortion-free amplified sensor output signal are designed. WIFI wireless network is used to transmit the voltage detection to LabVIEW-based ground collection port and LabVIEW technology is adopted for signal reception, data processing and analysis and other functions. Finally, a test platform is established to simulate the performance of the whole test system of single-phase voltage transformer. Test results indicate that this voltage transformer has sound real-time performance, high accuracy and fast response speed and the simulation test system is stable and reliable and can be a new prototype of voltage transformers.

  2. Cation/Anion Substitution in Cu2ZnSnS4 for Improved Photovoltaic Performance

    Science.gov (United States)

    Ananthoju, Balakrishna; Mohapatra, Jeotikanta; Jangid, Manoj K.; Bahadur, D.; Medhekar, N. V.; Aslam, M.

    2016-10-01

    Cations and anions are replaced with Fe, Mn, and Se in CZTS in order to control the formations of the secondary phase, the band gap, and the micro structure of Cu2ZnSnS4. We demonstrate a simplified synthesis strategy for a range of quaternary chalcogenide nanoparticles such as Cu2ZnSnS4 (CZTS), Cu2FeSnS4 (CFTS), Cu2MnSnS4 (CMTS), Cu2ZnSnSe4 (CZTSe), and Cu2ZnSn(S0.5Se0.5)4 (CZTSSe) by thermolysis of metal chloride precursors using long chain amine molecules. It is observed that the crystal structure, band gap and micro structure of the CZTS thin films are affected by the substitution of anion/cations. Moreover, secondary phases are not observed and grain sizes are enhanced significantly with selenium doping (grain size ~1 μm). The earth-abundant Cu2MSnS4/Se4 (M = Zn, Mn and Fe) nanoparticles have band gaps in the range of 1.04–1.51 eV with high optical-absorption coefficients (~104 cm‑1) in the visible region. The power conversion efficiency of a CZTS solar cell is enhanced significantly, from 0.4% to 7.4% with selenium doping, within an active area of 1.1 ± 0.1 cm2. The observed changes in the device performance parameters might be ascribed to the variation of optical band gap and microstructure of the thin films. The performance of the device is at par with sputtered fabricated films, at similar scales.

  3. PI and Fuzzy Control Strategies for High Voltage Output DC-DC Boost Power Converter - Hardware Implementation and Analysis

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Siano, Pierluigi

    2016-01-01

    converter with inbuilt voltage-lift technique and overcome the aforementioned deficiencies. Further, the control strategy is adapted based on proportional-integral (P-I) and fuzzy logic, closed-loop controller to regulate the outputs and ensure the performances. Complete hardware prototype of EHV converter......This paper presents the control strategies by Proportional-Integral (P-I) and Fuzzy Logic (FL) for a DC-DC boost power converter for high output voltage configuration. Standard DC-DC converters are traditionally used for high voltage direct current (HVDC) power transmission systems. But, lack its...... performances in terms of efficiency, reduced transfer gain and increased cost with sensor units. Moreover, the internal self-parasitic components reduce the output voltage and efficiency of classical high voltage converters (HVC). This investigation focused on extra high-voltage (EHV) DC-DC boost power...

  4. A sensorless control method for capacitor voltage balance and circulating current suppression of modular multilevel converter

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Loh, Poh Chiang

    2015-01-01

    There are several problems in the Modular Multilevel Converter (MMC), such as the appearance of circulating current, capacitor voltage unbalance and the requirement for a high number of sensors. All these problems will decrease the reliability and raise the cost/uncertainty of using MMC solutions....... As a result, a sensorless control method is proposed in this paper, which targets to improve the performances of MMC in respect to the above mentioned disadvantages: To decrease the cost and simplify the physical implementation, a state observer is proposed and designed to estimate both the capacitor voltages...... and the circulating currents in order to replace the high numbers of sensors. Furthermore, a control method combining the circulating current suppression and the capacitor voltage balancing is conducted based on the proposed state observer. It is concluded that the proposed state observer and control method can...

  5. Vibrissa Sensor

    Science.gov (United States)

    2016-09-30

    Docket No. 300119 1 of 11 VIBRISSA SENSOR STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and used by...REFERENCE TO OTHER PATENT APPLICATIONS [0002] None. BACKGROUND OF THE INVENTION (1) Field of the Invention [0003] The present invention provides a... measured as strain. [0009] Thus, there is a need for a sensor utilizing a vibrissa that can detect dynamic and high frequency movement of the

  6. Vibration sensors

    Science.gov (United States)

    Gupta, Amita; Singh, Ranvir; Ahmad, Amir; Kumar, Mahesh

    2003-10-01

    Today, vibration sensors with low and medium sensitivities are in great demand. Their applications include robotics, navigation, machine vibration monitoring, isolation of precision equipment & activation of safety systems e.g. airbags in automobiles. Vibration sensors have been developed at SSPL, using silicon micromachining to sense vibrations in a system in the 30 - 200 Hz frequency band. The sensing element in the silicon vibration sensor is a seismic mass suspended by thin silicon hinges mounted on a metallized glass plate forming a parallel plate capacitor. The movement of the seismic mass along the vertical axis is monitored to sense vibrations. This is obtained by measuring the change in capacitance. The movable plate of the parallel plate capacitor is formed by a block connected to a surrounding frame by four cantilever beams located on sides or corners of the seismic mass. This element is fabricated by silicon micromachining. Several sensors in the chip sizes 1.6 cm x 1.6 cm, 1 cm x 1 cm and 0.7 cm x 0.7 cm have been fabricated. Work done on these sensors, techniques used in processing and silicon to glass bonding are presented in the paper. Performance evaluation of these sensors is also discussed.

  7. Uncoupling charge movement from channel opening in voltage-gated potassium channels by ruthenium complexes.

    Science.gov (United States)

    Jara-Oseguera, Andrés; Ishida, Itzel G; Rangel-Yescas, Gisela E; Espinosa-Jalapa, Noel; Pérez-Guzmán, José A; Elías-Viñas, David; Le Lagadec, Ronan; Rosenbaum, Tamara; Islas, León D

    2011-05-06

    The Kv2.1 channel generates a delayed-rectifier current in neurons and is responsible for modulation of neuronal spike frequency and membrane repolarization in pancreatic β-cells and cardiomyocytes. As with other tetrameric voltage-activated K(+)-channels, it has been proposed that each of the four Kv2.1 voltage-sensing domains activates independently upon depolarization, leading to a final concerted transition that causes channel opening. The mechanism by which voltage-sensor activation is coupled to the gating of the pore is still not understood. Here we show that the carbon-monoxide releasing molecule 2 (CORM-2) is an allosteric inhibitor of the Kv2.1 channel and that its inhibitory properties derive from the CORM-2 ability to largely reduce the voltage dependence of the opening transition, uncoupling voltage-sensor activation from the concerted opening transition. We additionally demonstrate that CORM-2 modulates Shaker K(+)-channels in a similar manner. Our data suggest that the mechanism of inhibition by CORM-2 may be common to voltage-activated channels and that this compound should be a useful tool for understanding the mechanisms of electromechanical coupling.

  8. A study on InSb Magnetic Sensor Using Hall Effect

    Energy Technology Data Exchange (ETDEWEB)

    Chon, C.S. [Inha Univ., Inchon (Korea, Republic of)

    1994-02-01

    InSb thin film magnetic sensor, which have been prepared on glass substrate by vacuum evaporation, is investigated in this paper. The dependence of hall voltage with on magnetic field and temperature is examined by Hall effect. The variation of Hall voltage with magnetic field is almost linear at constant current drive but it is deviated from the linearity at constant voltage drive. Hall voltage decreases as the ambient temperature increases, so it is necessary to take into account the temperature effect when the InSb thin film is used as magnetic sensor. (author). 17 refs., 5 figs.

  9. Over-voltage protection system and method

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Song; Dong, Dong; Lai, Rixin

    2017-05-02

    An over-voltage protection system includes an electronic valve connected across two terminals of a circuit and an over-voltage detection circuit connected across one of the plurality of semiconductor devices for detecting an over-voltage across the circuit. The electronic valve includes a plurality of semiconductor devices connected in series. The over-voltage detection circuit includes a voltage divider circuit connected to a break-over diode in a way to provide a representative low voltage to the break-over diode and an optocoupler configured to receive a current from the break-over diode when the representative low voltage exceeds a threshold voltage of the break-over diode indicating an over-voltage condition. The representative low voltage provided to the break-over diode represents a voltage across the one semiconductor device. A plurality of self-powered gate drive circuits are connected to the plurality of semiconductor devices, wherein the plurality of self-powered gate drive circuits receive over-voltage triggering pulses from the optocoupler during the over-voltage condition and switch on the plurality of semiconductor devices to bypass the circuit.

  10. Improving Efficiency of Evaporated Cu2ZnSnS4 Thin Film Solar Cells by a Thin Ag Intermediate Layer between Absorber and Back Contact

    Directory of Open Access Journals (Sweden)

    Hongtao Cui

    2015-01-01

    Full Text Available A 20 nm Ag coating on Mo back contact was adopted to improve the back contact of evaporated Cu2ZnSnS4 (CZTS solar cells. The Ag layer helped reduce the thickness of MoS2 which improves fill factor (FF significantly; additionally, it reduced secondary phases ZnS and SnS2−x, which may help carrier transport; it was also involved in the doping of the absorber layer, which compensated the intrinsic p-type doping and therefore drags down the doping level. The doping involvement may enlarge the depletion region and improve lifetime of the absorber, which led to enhancing open circuit voltage (VOC, short circuit current density (JSC, and efficiency significantly. However, it degrades the crystallinity of the material slightly.

  11. Advances in high voltage engineering

    CERN Document Server

    Haddad, A

    2005-01-01

    This book addresses the very latest research and development issues in high voltage technology and is intended as a reference source for researchers and students in the field, specifically covering developments throughout the past decade. This unique blend of expert authors and comprehensive subject coverage means that this book is ideally suited as a reference source for engineers and academics in the field for years to come.

  12. High Voltage Pulse Testing Survey.

    Science.gov (United States)

    1985-10-01

    Cryogenic 23 E. Liquids 26 F. Solids 28 1. Polyethylene 28 2. Cross-Linked Polyethylene ( XLPE ) 29 3. Polyimide and Polyvenylchloride (PVC) 31 VI Benefits 35 A...Strength of XLPE Cables 29 vii * 4" I PROGRAM OBJECTIVES The Pulse Test Survey summarizes government, industry, and technical reports on high voltage pulse...system of silicone oil on a XLPE (cross-linked polyethylene) spacer tends to lower the impulse breakdown by approximately 10 percent. The negative impulse

  13. TRANSISTOR HIGH VOLTAGE POWER SUPPLY

    Science.gov (United States)

    Driver, G.E.

    1958-07-15

    High voltage, direct current power supplies are described for use with battery powered nuclear detection equipment. The particular advantages of the power supply described, are increased efficiency and reduced size and welght brought about by the use of transistors in the circuit. An important feature resides tn the employment of a pair of transistors in an alternatefiring oscillator circuit having a coupling transformer and other circuit components which are used for interconnecting the various electrodes of the transistors.

  14. Low Cost Smart Sensor Design

    Directory of Open Access Journals (Sweden)

    Dr. T.A. Al Smadi

    2011-01-01

    Full Text Available Problem statement: Sensor with local processing power that enables it to react to local conditions without having to refer back to the central controller. The size and the cost of smart sensor circuit have been reduced. Approach: The use of microcontroller, such as (PIC16C715, with an 8- bit ADC (Analogue to Digital Converter in one chip. This reduction in the circuit size makes it possible sometimes to incorporate the primary sensor with the signal processing circuit in one unit, then the lookup table should be modified accordingly. The program mobility of smart sensor enables the system to perform self calibration routine by applying known input voltage signal, where its corresponding expected value is stored in the self calibration code. Results: The correction for the measurement signal is done by multiplying the measured signal by the gain correction value and then adding the result of the multiplication to the offset compensation value. The smart sensor performs the self calibration routine for every new measurement value, to adapt any changes in the system environment such as temperature drift. Conclusion: The system performance has been enhanced by implementing the PIC16C715 Circuit design complexity and cost has been reduced and also it’s easy to upgrade.

  15. Low voltage electron beam accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Masafumi [Iwasaki Electric Co., Ltd., Tokyo (Japan)

    2003-02-01

    Widely used electron accelerators in industries are the electron beams with acceleration voltage at 300 kV or less. The typical examples are shown on manufactures in Japan, equipment configuration, operation, determination of process parameters, and basic maintenance requirement of the electron beam processors. New electron beam processors with acceleration voltage around 100 kV were introduced maintaining the relatively high dose speed capability of around 10,000 kGy x mpm at production by ESI (Energy Science Inc. USA, Iwasaki Electric Group). The application field like printing and coating for packaging requires treating thickness of 30 micron or less. It does not require high voltage over 110 kV. Also recently developed is a miniature bulb type electron beam tube with energy less than 60 kV. The new application area for this new electron beam tube is being searched. The drive force of this technology to spread in the industries would be further development of new application, process and market as well as the price reduction of the equipment, upon which further acknowledgement and acceptance of the technology to societies and industries would entirely depend. (Y. Tanaka)

  16. A novel readout system for wireless passive pressure sensors

    Science.gov (United States)

    Zhang, Huixin; Hong, Yingping; Ge, Binger; Liang, Ting; Xiong, Jijun

    2014-03-01

    This paper presents a novel readout system for wireless passive pressure sensors based on the inductively coupled inductor and cavity (LC) resonant circuits. The proposed system consists of a reader antenna inductively coupled to the sensor circuit, a readout circuit, and a personal computer (PC) post processing unit. The readout circuit generates a voltage signal representing the sensor's capacitance. The frequency of the reader antenna driving signal is a constant, which is equal to the sensor's resonant frequency at zero pressure. Based on mechanical and electrical modeling, the pressure sensor design based on the high temperature co-fired ceramic (HTCC) technology is conducted and discussed. The functionality and accuracy of the readout system are tested with a voltage-capacitance measurement system and demonstrated in a realistic pressure measurement environment, so that the overall performance and the feasibility of the readout system are proved.

  17. The Domain II S4-S5 Linker in Nav1.9: A Missense Mutation Enhances Activation, Impairs Fast Inactivation, and Produces Human Painful Neuropathy.

    Science.gov (United States)

    Han, Chongyang; Yang, Yang; de Greef, Bianca T A; Hoeijmakers, Janneke G J; Gerrits, Monique M; Verhamme, Camiel; Qu, Jian; Lauria, Giuseppe; Merkies, Ingemar S J; Faber, Catharina G; Dib-Hajj, Sulayman D; Waxman, Stephen G

    2015-06-01

    Painful small fiber neuropathy is a challenging medical condition with no effective treatment. Non-genetic causes can be identified in one half of the subjects. Gain-of-function variants of sodium channels Nav1.7 and Nav1.8 have recently been associated with painful small fiber neuropathy. More recently, mutations of sodium channel Nav1.9 have been linked to human pain disorders, with two gain-of-function mutations found in patients with painful small fiber neuropathy. Here we report a novel Nav1.9 mutation, a glycine 699 substitution by arginine (G699R) in the domain II S4-S5 linker, identified in a patient with painful small fiber neuropathy. In this study, we assayed the mutant channels by voltage-clamp in superior cervical ganglion neurons, which do not produce endogenous Nav1.8 or Nav1.9 currents, and provide a novel platform where Nav1.9 is expressed at relatively high levels. Voltage-clamp analysis showed that the mutation hyperpolarizes (-10.1 mV) channel activation, depolarizes (+6.3 mV) steady-state fast inactivation, slows deactivation, and enhances ramp responses compared with wild-type Nav1.9 channels. Current-clamp analysis showed that the G699R mutant channels render dorsal root ganglion neurons hyperexcitable, via depolarized resting membrane potential, reduced current threshold and increased evoked firing. These observations show that the domain II S4-S5 linker plays an important role in the gating of Nav1.9 and demonstrates that a mutation in this linker is linked to a common pain disorder.

  18. Research experiments on pressure-difference sensors with ferrofluid

    Energy Technology Data Exchange (ETDEWEB)

    Ruican, Hao, E-mail: haoruican@163.com [School of Mechanical Engineering, Beijing Polytechnic, Beijing 100176 (China); Huagang, Liu; Wen, Gong; Na, Zhang [School of Mechanical Engineering, Beijing Polytechnic, Beijing 100176 (China); Ruixiao, Hao [Civil and Architectural Engineering Institute of CCCC-FHEB Co., Ltd., Beijing 101102 (China)

    2016-10-15

    Ferrofluid has distinctive properties and can be applied in many industrial uses, especially in sensors. The principles of pressure-difference sensors with ferrofluid were illustrated and experiments were demonstrated. Four types of ferrofluids with different concentrations were selected for the experiments performed. Then, the parameters of ferrofluid, such as density and magnetization, were measured. The magnetization curves of the ferrofluid were sketched. Four U tubes with different diameters were designed and built. Experiments were conducted to analyze the impacts of tube diameter and ferrofluid concentration on the output voltage/pressure difference performance. According to the experiment results, the tube diameter has little effect on the sensor output voltage. With the concentration of ferrofluid increasing, the output voltage and sensitivity of the pressure-difference sensor increases. The measurable range of the sensor also increases with the increasing concentration of ferrofluid. The workable range and the sensitivity of the designed sensor were (−2000~+2000)Pa and 1.26 mV/Pa, respectively. - Highlights: • The principle of pressure difference sensor with ferrofluid was illustrated. • The parameters of ferrofluid, such as density and magnetization, were measured. The magnetization curves of the ferrofluid were sketched. • Four series of U tubes with different diameter were designed and manufactured. • The experiments were made to analyze the factors of the tube diameter and the concentration of ferrofluid on the output-input pressure difference. • The sensitivity of the pressure difference sensor with ferrofluid was studied and the corresponding conclusions were obtained.

  19. Triboelectric Hydrogen Gas Sensor with Pd Functionalized Surface

    Directory of Open Access Journals (Sweden)

    Sung-Ho Shin

    2016-10-01

    Full Text Available Palladium (Pd-based hydrogen (H2 gas sensors have been widely investigated thanks to its fast reaction and high sensitivity to hydrogen. Various sensing mechanisms have been adopted for H2 gas sensors; however, all the sensors must be powered through an external battery. We report here an H2 gas sensor that can detect H2 by measuring the output voltages generated during contact electrification between two friction surfaces. When the H2 sensor, composed of Pd-coated ITO (indium tin oxide and PET (polyethylene Terephthalate film, is exposed to H2, its output voltage is varied in proportion to H2 concentration because the work function (WF of Pd-coated surface changes, altering triboelectric charging behavior. Specifically, the output voltage of the sensor is gradually increased as exposing H2 concentration increases. Reproducible and sensitive sensor response was observed up 1% H2 exposure. The approach introduced here can easily be adopted to development of triboelectric gas sensors detecting other gas species.

  20. Piezo Voltage Controlled Planar Hall Effect Devices

    OpenAIRE

    Bao Zhang; Kang-Kang Meng; Mei-Yin Yang; Edmonds, K. W.; Hao Zhang; Kai-Ming Cai; Yu Sheng; Nan Zhang; Yang Ji; Jian-Hua Zhao; Hou-Zhi Zheng; Kai-You Wang

    2015-01-01

    The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the pie...