bluuebunny/crossref_metadata_2025 huggingface dataset:
Synaptic NMDA receptors in developing mouse hippocampal neurones: functional properties and sensitivity to ifenprodil.
Authors: Kirson E D , Yaari Y
Published: December 2014

1. Whole‐cell patch‐clamp techniques were used to record pharmacologically isolated NMDA receptor‐mediated EPSCs (NMDA EPSCs) from CA1 pyramidal cells (PCs) in hippocampal slices from 4‐day‐old to 36‐week‐old mice, in order to characterize developmental changes in functional properties and subunit composition of synaptic NMDA receptors. 2. During the first postnatal weeks the dendritic tree of CA1 PCs stained with biocytin increased both in size and in complexity. This was associated with an increase in amplitude of the focally evoked NMDA EPSCs recorded either in nominally Mg(2+)‐free or Mg(2+)‐containing saline. In adult PCs (> 5 weeks old) EPSC amplitude was 4‐fold larger than in very young (up to 2 weeks old) neurones. 3. The sensitivity of NMDA EPSCs to blockade by Mg2+ did not change with age. In very young, intermediate and adult PCs the EPSC‐voltage relation displayed an area of negative slope conductance at membrane potentials more negative than ‐30 mV. The apparent Kd values of the NMDA receptors for Mg2+ at 0 mV were 7.8 +/‐ 6.4, 10.4 +/‐ 14.1 and 6.5 +/‐ 4.7 mM in very young, intermediate and adult neurones, respectively. 4. The decay of the NMDA EPSC in both young and adult neurones could be described by the sum of a fast and a slow exponential function. Both EPSC rise time and fast and slow decay time constants measured at ‐60 mV, decreased with age. 5. The decay of NMDA EPSCs in young versus adult PCs was differentially modulated by membrane voltage. In young PCs depolarization slowed both the fast and the slow EPSC components. In adult PCs depolarization slightly accelerated the initial EPSC decay, though the overall duration of the EPSC did not change. The rise time of the EPSCs was not affected by voltage at any age. 6. The subunit‐selective NMDA receptor antagonist ifenprodil similarly blocked iontophoretic NMDA‐induced currents and NMDA EPSCs. In both young and adult PCs, the concentration‐response curves for this effect disclosed distinct low and high affinity binding sites for ifenprodil. 7. In young PCs, low and high affinity binding sites for ifenprodil were about equally expressed (57 versus 43%, respectively), whereas in adult PCs, synaptic NMDA receptors expressed a majority (78%) of low affinity binding sites for ifenprodil. 8. The long duration of NMDA EPSCs (and by implication, of Ca2+ transfer through NMDA receptor channels) and its further prolongation by depolarization in young PCs are consistent with heightened NMDA‐dependent neuronal plasticity early in development. The age‐related changes in these properties may result from a developmental change in NMDA receptor subunit composition.
A transferable, beta‐naphthoflavone‐inducible, hyperpolarizing factor is synthesized by native and cultured porcine coronary endothelial cells.
Authors: Popp R , Bauersachs J , Hecker M , Fleming I , Busse R
Published: December 2014

1. The vascular endothelium releases a hyperpolarizing factor (endothelium‐derived hyperpolarizing factor, EDHF) tentatively identified as a cytochrome P450‐derived arachidonic acid metabolite. However, there is still controversy concerning its transferability and identity. We designed a bioassay system for assessing EDHF release in which the membrane potential was recorded in cultured vascular smooth muscle cells located downstream from donor endothelial cells. 2. Under combined nitric oxide (NO) synthase and cyclo‐oxygenase blockade with NG‐nitro‐L‐arginine (100 mumol l‐1) and diclofenac (10 mumol l‐1), the superfusate from bradykinin (30 mumol l‐1)‐stimulated, cultured porcine coronary endothelial cells induced a distinct hyperpolarization followed by a depolarization. Direct application of bradykinin to the smooth muscle cells resulted solely in membrane depolarization. Similar results were obtained using bradykinin‐stimulated porcine coronary arteries as donor. 3. Single‐channel current measurements suggest that this EDHF‐induced hyperpolarization was elicited by the activation of Ca(2+)‐dependent K+ channels. 4. Increasing the transmural pressure within the donor segment significantly enhanced the duration, but not the amplitude of the hyperpolarization induced by the effluate from bradykinin‐stimulated donor segments. 5. Inhibition of P450 oxygenase activity with clotrimazole (3 mumol l‐1) or 17‐octadecynoic acid (3 mumol l‐1) abolished EDHF release from the coronary endothelium, while the P450‐derived arachidonic acid metabolite, 5,6‐epoxyeicosatrienoic acid, induced a hyperpolarization of detector smooth muscle cells almost identical to that induced by EDHF. Moreover, induction of P450 activity by beta‐naphthoflavone (3 mumol l‐1, 48 h), significantly increased the bradykinin‐induced release of EDHF. 6. These findings suggest that the vascular endothelium releases a transferable hyperpolarizing factor, chemically distinct from NO and prostacyclin, in response to agonists and mechanical stimulation. This beta‐naphthoflavone‐inducible EDHF appears to be a cytochrome P450‐derived metabolite of arachidonic acid, which elicits hyperpolarization by activation of Ca(2+)‐dependent K+ channels.
Properties and functions of Na(+)‐activated K+ channels in the soma of rat motoneurones.
Authors: Safronov B V , Vogel W
Published: December 2014

1.Properties and functions of Na(+)‐activated K+ (KNa) channels in the soma of motoneurones were studied in spinal cord slices of newborn rat. KNa channels had a conductance of 44.8 pS in 5.6 mM external K+ (Ko+)/106 mM internal K+ (Ki+) solutions and 139.2 pS in 155 mM Ko+/85 mM Ki+ solutions. KNa channels were voltage independent and needed a relatively high [Na+]i to become active (EC50 = 39.9 mM). Li+ could not substitute for Na+ in activation of KNa channels. The channels were predominantly found in the vicinity of cell processes, in the regions of most probable accumulation of cytoplasmic Na+. 2. In current‐clamp experiments, the shape of the single action potential (AP) recorded in Ca(2+)‐free Ringer solution was not changed after substitution of external Na+ with Li+. However, 0.4‐0.8 s trains of APs were followed by a slow (1‐2s) after‐hyperpolarization (sAHP), which reversibly disappeared when external Na+ was replaced by Li+. Na(+)‐activated sAHP persisted after addition of ouabain and its amplitude was even increased in K(+)‐free Ringer solution. sAHP disappeared when the membrane potential was equal to the K+ equilibrium potential. This indicated that sAHP resulted from activation of a Na(+)‐dependent K+ conductance, rather than from activation of the electrogenic Na(+)‐K+ pump. 3. In conclusion, KNa channels can play an important role in excitability of motoneurones. KNa channels do not make a contribution to the single AP, but they can be activated by a local accumulation of internal Na+ during trains of APs. A Na(+)‐activated K+ conductance can reduce membrane excitability and contribute to regulation of AP firing in motoneurones.
Protein kinase A‐mediated enhancement of miniature IPSC frequency by noradrenaline in rat cerebellar stellate cells.
Authors: Kondo S , Marty A
Published: December 2014

1. Cellular mechanisms underlying the enhancement by noradrenaline (NA) of inhibitory postsynaptic currents (IPSCs) were studied at inhibitory synapses in the molecular layer of the cerebellum. IPSCs were obtained from stellate cells in rat cerebellar slices using tight‐seal whole‐cell recording. 2. Miniature IPSCs (mIPSCs) were recorded in the presence of tetrodotoxin (TTX; 100 nM). NA (10 microM) markedly increased the frequency of mIPSCs, but did not alter their mean amplitude. Bath application of the inhibitor of adenylyl cyclase 9‐(tetrahydro‐2'‐furyl) adenine (SQ 22,536; 300 microM), of the wide spectrum protein kinase inhibitor staurosporine (1 microM), and of the Rp‐diastereomer of adenosine‐3',5'‐cyclic monophosphothioate (Rp‐cAMPS; 500 microM), a specific inhibitor of cAMP‐dependent protein kinase (PKA), inhibited the mIPSC frequency increase induced by NA. 3. The increase in mIPSC frequency was not attenuated by Cd2+ (100 microM), a blocker of voltage dependent calcium channels. However, after a 12‐15 min pre‐incubation in Ca(2+)‐free saline, the effect of NA on mIPSCs was markedly inhibited. If Ca2+ ions were readmitted in the presence of NA, enhancement of the mIPSC frequency was largely restored. 4. Application of the membrane permeant analogue of cAMP, 8‐Br‐cAMP (1 mM), together with the inhibitor of cAMP phosphodiesterase, 3‐isobutyl‐1‐methylxanthine (IBMX; 100 microM), caused a frequency increase of mIPSCs. Forskolin also mimicked the stimulatory effect of NA on mIPSC frequency. The effects of both 8‐Br‐cAMP and forskolin persisted in Ca(2+)‐free saline, suggesting that the modulation of transmitter release does not require Ca2+ influx. 5. On the whole, the results indicate that the potentiation of mIPSC frequency by NA is mediated through the sequential activation of adenylyl cyclase and protein kinase A (PKA), and that PKA modulates the vesicle release mechanism rather than Ca2+ influx. The lack of effect of NA after prolonged incubation in Ca(2+)‐free solution may be due to an inhibition of adenylyl cyclase by a gradual lowering of the cytosolic presynaptic Ca2+ concentration.
Dynamic properties of nitric oxide release from parallel fibres in rat cerebellar slices.
Authors: Shibuki K , Kimura S
Published: December 2014

1. Nitric oxide (NO) release following repetitive electrical stimulation was studied in the molecular layer of rat cerebellar slices using electrochemical NO probes. 2. In parasagittal slices of the vermis, most Purkinje cells showed climbing fibre responses in response to white matter stimulation without accompanying NO release. 3. In frontal slices, parallel fibre volley potentials and NO release were elicited concurrently by parallel fibre stimulation. 4. The NO release following parallel fibre stimulation was not affected by blockers of non‐NMDA, NMDA and metabotropic glutamate receptors. 5. The NO release was reduced significantly (P < 0.001) to 29% of the control level after climbing fibre deafferentation with 3‐acetylpyridine treatment. 6. The rate of NO release was roughly proportional to the second or third power of the stimulus frequency, and to the third power of the extracellular Ca2+ concentration. 7. The rate of NO release was not affected by nicardipine (10 microM). It was reduced to 87 +/‐ 4% (n = 5, mean +/‐ S.E.M.) of the control level by omega‐conotoxin GVIA (0.3 microM), and to 18 +/‐ 4% (n = 4) by omega‐agatoxin IVA (0.3 microM). 8. Tetanic parallel fibre stimulation potentiated NO release by 24 +/‐ 5% (n = 5). 9. These data indicate that NO is derived mainly from parallel fibres. The relationship between NO release and cerebellar synaptic plasticity is discussed.
Effects of Ostertagia ostertagi on gastrin gene expression and gastrin‐related responses in the calf.
Authors: Purewal A , Fox M T , Shivalkar P , Carroll A P , Uche U E , Vaillant C , Watkinson A
Published: December 2014

1. Infection with the bovine abomasal nematode Ostertagia ostertagi results in a loss of acid‐secreting parietal cells and an increase in gastric pH. The effects of an experimental infection on gastrin mRNA expression, blood and tissue gastrin concentrations, the different molecular forms of gastrin in each, and pyloric mucosal chromogranin A‐derived peptides were investigated in the calf. 2. An increase in blood gastrin concentrations in the infected group reached a peak by day 28 postinfection (635 pg ml‐1; P < 0.01). Gel chromatography analysis of blood samples revealed that the hypergastrinaemia comprised largely gastrin‐34 (G‐34) in parasitized calves while gastrin‐17 (G‐17) predominated in control animals. 3. An 11‐fold increase in gastrin mRNA expression was recorded in the parasitized animals which was accompanied by a 23.8% reduction in pyloric mucosal gastrin content and an apparent drop of 24.7% in the number of gastrin‐producing G cells detected. There was no major change in the relative abundance of G‐17 and G‐34 in the pyloric mucosa of infected calves. No significant differences in the concentration of pyloric mucosal chromogranin A‐derived peptides were recorded between infected and control groups. 4. These data suggest that the hypergastrinaemia seen in parasitized calves results largely from an increase in gastrin synthesis and that depletion of previously stored peptide makes virtually no contribution to elevated blood gastrin concentrations.
Recurrent inhibition between motor nuclei innervating opposing wrist muscles in the human upper limb.
Authors: Aymard C , Decchi B , Katz R , Lafitte C , Pénicaud A , Raoul S , Rossi A
Published: December 2014

1. Effects of conditioning motor volleys of increasing amplitude on antagonistic motor nuclei were tested at the wrist and elbow level in man. 2. The modifications of biceps, triceps, flexor carpi radialis (FCR) and extensor carpi radialis (ECR) motoneurone excitability were tested both in post‐stimulus time histogram (PSTH) and rectified averaged EMG experiments. 3. Conditioning motor volleys were evoked in biceps, triceps, FCR and ECR muscles by electrical stimuli applied to the corresponding nerves. The intensity of the conditioning stimuli was systematically varied from an intensity just below motor threshold to one giving rise to a motor response equal to half of the maximal direct motor response (Mmax). 4. The effect of the injection of a cholinergist agonist, L‐acetylcarnitine (L‐Ac), on antagonistic conditioning motor volleys was tested for each motor nucleus. 5. Results obtained at the wrist and elbow level were strikingly different. Antagonistic motor volleys resulted in an early and long‐lasting inhibition enhanced by L‐Ac injection in wrist motor nuclei, while no modification was observed in elbow motor nuclei. 6. The characteristics of the early and long‐lasting inhibition evoked in wrist motor nuclei by antagonistic motor volleys suggest that they are due to the activation of Renshaw cells by the conditioning motor volleys. 7. It is therefore concluded that these experiments provide further evidence that the interconnections between motoneurones, interneurones mediating reciprocal inhibition and Renshaw cells at the wrist level are different from those described elsewhere. Indeed, it has already been shown that the interneurones mediating reciprocal inhibition between FCR and ECR are not inhibited by Renshaw cells, and the results presented here suggest that FCR‐coupled Renshaw cells inhibit ECR motoneurones and vice versa.
Biophysical properties of heterotypic gap junctions newly formed between two types of insect cells.
Authors: Bukauskas F F , Vogel R , Weingart R
Published: December 2014

1. Cell pairs of the insect cell line Sf9 (Spodoptera frugiperda) were chosen to examine the electrical properties of gap junction channels. The dual voltage‐clamp method was used to control the membrane potential of each cell (Vm,1 and Vm,2) and hence the junctional voltage gradient (Vj), and to measure intercellular current. 2. Studies with preformed pairs revealed that the gap junction conductance (gj) is controlled by a Vj‐ and a Vm‐sensitive gate. At steady state, gj = f(Vj) was bell shaped and symmetrical (Boltzmann: Vj.0 = ‐54 and 55 mV, the normalized minimum conductance at large Vj values (gj,min) = 0.24 and 0.23, z = 5.5 and 6.1 for negative and positive Vj, respectively) and gj = f(Vm) was S shaped (Vm.0 = 13 mV, gj,min = 0, z = 1.5). 3. Single channels exhibited two conductances, a main state (gamma j,main) of 224 pS and a residual state (gamma j,residual) of 42 pS. 4. We conclude that gap junctions in Sf9 cells behave similarly to those in the insect cell line C6/36 (Aedes albopictus). 5. An induced cell pair approach was used to examine heterotypic gap junction channels between Sf9 cells and C3/36 cells. 6. Heterotypic channels showed a gamma j,main of 303 pS and a gamma j,residual of 45 and 64 pS, depending on whether the Sf9 cell or C6/36 cell was positive inside. 7. In heterotypic gap junctions, gj = f(Vj) was bell shaped and asymmetrical (gj was more sensitive to Vj when the C6/36 cell was positive inside) and gj = f(Vm) was S shaped (Vm,0 = 2 mV, gj,min = 0, z = 2.9). 8. We conclude that heterotypic channels possess a Vj‐ and Vm‐sensitive gating mechanism. Vj gating involves two gates, one located in each hemi‐channel. Vj gates are operated independently and close when the cytoplasmic aspect is made positive. 9. A comparison of homo‐ and heterotypic channel data suggests that docking of hemi‐channels may affect channel gating, but not channel conductance.
3‐hydroxybutyrate blocks the transient K+ outward current in myocardial mouse cells in a stereoselective fashion.
Authors: Doepner B , Thierfelder S , Hirche H , Benndorf K
Published: December 2014

1. Mouse ventricular myocytes develop a large transient K+ outward current (I(TO)) which accelerates repolarization and is a crucial determinant for the regulation of the action potential duration at various heart rates. The effect of 3‐hydroxybutyrate on I(TO) was investigated under voltage‐ and current‐clamp conditions. 2. The drug blocked I(TO) in a stereoselective manner with the L‐enantiomer being the effective and the D‐enantiomer, the ineffective form. The blocking action of the L‐enantiomer was established immediately and it could be completely washed out within several tens of seconds. 3. The dose‐response characteristic for the peak I(TO) showed a strict 1:1 binding of the drug to the receptor with a concentration of half‐maximum effect of 2.1 mmol l(‐1). 4. The action of L‐hydroxybutyrate was voltage independent, did not need channel opening and preferentially affected the slow component of both inactivation and recovery from inactivation. 5. At the high concentration of 20 mmol l(‐1) the optically inactive form, the racemate, did not affect I(TO), indicating that the ineffective D‐enantiomer interacts with the channels at much lower concentrations. 6. At a concentration of 10 mmol l(‐1), L‐hydroxybutyrate prolonged the action potential by 218 +/‐ 26 and 127 +/‐ 10% (means +/‐ S.E.M.) at 50 and 90% repolarization, respectively. 7. It is concluded that the non‐physiological L‐hydroxybutyrate is a novel type of blocker of I(TO), It interacts either with the channel itself, or with a receptor protein closely related to the channel and preferentially affects slow inactivation.
Modulation of dog atrial swelling‐induced chloride current by cAMP: protein kinase A‐dependent and ‐independent pathways.
Authors: Du X Y , Sorota S
Published: December 2014

1. The modulation of dog atrial swelling‐induced chloride current (I(Cl,swelling)) by cAMP‐elevating agents was studied. Forskolin (10 microM) or isoprenaline (1 microM) exerted multiple effects. Although the pattern between cells was variable, there was, in general, a stimulatory action and a more slowly developing inhibitory effect. 2. In any given cell, the response to forskolin or isoprenaline was qualitatively similar suggesting that all of the responses were dependent on stimulation of adenylyl cyclase. The effects of forskolin or isoprenaline on I(Cl,swelling) were inhibited by intracellular dialysis with a P‐site inhibitor of adenylyl cyclase, 2'‐deoxyadenosine 3'‐monophosphate (300 microM). 3. Intracellular dialysis with a peptide inhibitor of protein kinase A (PKI(6‐22); 100 microM) blocked the inhibitory response to forskolin or isoprenaline and all cells responded with a monophasic stimulation of I(Cl,swelling). 4. After intracellular dialysis of cells with PKI(6‐22) (100 microM) and cAMP (100 microM), current amplitude was not further stimulated by forskolin. 5. After intracellular dialysis with PKI(6‐22) and adenosine 5'‐O‐(3‐thiotriphosphate) (ATPgammaS), forskolin stimulated I(Cl,swelling) and the effect of forskolin subsided after it was washed out. 6. In conclusion, there are dual pathways by which cAMP can modulate dog atrial cell I(Cl,swelling). Inhibition results from protein kinase A (PKA)‐dependent phosphorylation. In addition, a stimulatory pathway exists that is independent of phosphorylation by PKA or other cellular kinases. Although alternative explanations are possible, the stimulatory effect of cAMP may represent a direct modulation of I(Cl,swelling).
Ca2+ release‐induced inactivation of Ca2+ current in rat ventricular myocytes: evidence for local Ca2+ signalling.
Authors: Sham J S
Published: December 2014

1. Inactivation of Ca2+ current (ICa) induced by Ca2+ release from sarcoplasmic reticulum (SR) was studied in single rat ventricular myocytes using whole‐cell patch‐clamp and indo‐1 fluorescence measurement techniques. 2. Depolarizing pulses to 0 mV elicited large Ca2+ transients and ICa with biexponential inactivation kinetics. Varying SR Ca2+ loading by a 20 s pulse of caffeine showed that the fast component of ICa inactivation was dependent on the magnitude of Ca2+ release. 3. Inactivation of ICa induced by Ca2+ release was quantified, independently of voltage and Ca2+ entry, using a function termed fractional inhibition of ICa (FICa). The voltage relation of FICa had a negative slope, resembling that of single‐channel Ca2+ current (iCa) rather than the bell‐shaped current‐voltage (I‐V) relation of macroscopic ICa and Ca2+ transients. 4. Intracellular dialysis of myocytes with 10 mM EGTA (150 nM free [Ca2+]) had no effect on ICa inactivation induced by Ca2+ release, despite abolition of Ca2+ transients and cell contraction. Dialysis with 3 or 10 mM BAPTA (180 nM free [Ca2+]) attenuated FICa in a concentration‐dependent manner, with greater inhibition at positive than at negative potentials, consistent with more effective buffering of Ca2+ microdomains of smaller iCa. 5. Spatial profiles of [Ca2+] near an opened Ca2+ channel were simulated. [Ca2+] reached submillimolar levels at the mouth of the channel, and dropped steeply as radial distance increased. At any given distance from the channel, [Ca2+] was higher at negative than at positive potentials. The radii of Ca2+ microdomains were significantly reduced by 3 or 10 mM BAPTA, but not by 10 mM EGTA. 6. In conclusion, the distinctive voltage dependence and susceptibility of Ca2+ release‐induced ICa inactivation to fast and slow Ca2+ buffers suggests that the process is mediated through local changes of [Ca2+] in the vicinity of closely associated Ca2+ channels and ryanodine receptors.
Electroosmotic Flow Through Porous Materials
Authors: Saini Rakesh , Kenny Matthew , Barz Dominik P. J.
Published: December 2014

Electroosmotic flow can be employed in many microfluidic systems. Especially, highly porous materials are suitable since they generate significant flow rates and pressures.

In the current research, we employ electroosmosis experiments using a relatively simple and cost-effective set-up including different sets of sintered packed beds of borosilicate micro spheres having a wider range of porosities. Various experiments are performed with varying applied electric field, and packed bed porosity. The flow rates are measured by tracking the air/liquid interface in a capillary which is connected to the packed bed. A mathematical model of the setup reveals the influence of the capillary flow on the flow rate of the electroosmotic flow.
Study on Ice Plug and Ferrofluid Pulled by a Magnet in a Microchannel
Authors: Shibata Yuichi , Okamoto Osamu , Kawaji Masahiro
Published: December 2014

The field of microfluidics is fast developing with advances in MEMS, biotechnology and μ-TAS technologies. In various microfluidic devices, controlling the motion of liquid slugs and materials in a microchannel is necessary. In the biotechnology field, freezing of cells in a microchannel and transfer of frozen cells in a micro reactor are required. We previously studied the motion of liquid and air plugs by moving a ferrofluid plug electromagnetically. In this study, we focus on the formation and motion of an ice plug in a microchannel. First, an abrupt change from a supercooled water slug to the ice plug is observed. As the ice plug is heated and a water layer is produced between the tube wall and ice plug, the frozen ice plug is then moved in the microchannel by using a ferrofluid plug. By controlling the driving power exerted on the ferrofluid plug, the motion of the ice plug has been studied.
MHF (Minimum Heat Flux) Point on Anodized Zirconium Surface During Quenching
Authors: Kang Jun-young , Kim Seol Ha , Jo HangJin , Ahn Ho Seon , Kim Moo Hwan , Park Hyun Sun
Published: December 2014

Quenching experiment for the evaluation of the Minimum Heat Flux (MHF) point on an anodized zirconium surface was conducted. The anodized zirconium surface showed complete wetting (Contact Angle, ∼ 0°) due to the capillary wicking force by nano- and micro-scaled structures in contrast to bare zirconium surface (∼ 54.3±2°). The cylindrical test sections (bare and anodized zirconium surface) heated up to 800 [°C] by radiation furnace was rapidly immersed into saturated distilled water. The temperature history of the test section showed the enhancement of the MHF point noticeably from 324 [°C] for the bare to 497 [°C] for the anodized zirconium surface. High speed visualization focusing on the interfacial dynamics at the film boiling showed stable wavy motion at the bare zirconium surface. On the contrary, vigorous fluctuation of the liquid-vapor interface on the anodized zirconium surface occurred. The visual observation suggested that it was caused by completely wetting features at the anodized zirconium surface. Therefore, it triggered the enhancement of the MHF point.
Electrical Interconnect and Microfluidic Cooling Within 3D ICs and Silicon Interposer
Authors: Oh Hanju , Zhang Yue , Zheng Li , Bakir Muhannad S.
Published: December 2014

Heat dissipation is a significant challenge for three-dimensional integrated circuits (3D IC) due to the lack of heat removal paths and increased power density. In this paper, a 3D IC system with an embedded microfluidic cooling heat sink (MFHS) is presented. In the proposed 3D IC system, high power tiers contain embedded MFHS and high-aspect ratio (23:1) through-silicon-vias (TSVs) routed through the integrated MFHS. In addition, each tier has dedicated solder-based microfluidic chip I/Os. Microfluidic cooling experiments of staggered micropin-fins with embedded TSVs are presented for the first time. Moreover, the lateral thermal gradient across a chip is analyzed with segmented heaters.
Pressure Drop Analysis Using the Homogeneous Model for Open Microchannel With Manifold (OMM)
Authors: Kalani Ankit , Kandlikar Satish G.
Published: December 2014

Flow boiling in microchannels has the ability to dissipate high heat fluxes due to the associated small hydraulic diameter and latent heat effects. However, flow instabilities and early critical heat flux have often limited the heat transfer performance of such systems. In a previous study, the open microchannel with manifold (OMM) design was introduced to address these issues. Low pressure drop at high heat flux were obtained with this configuration. In this work, theoretical modeling of pressure drop for the OMM geometry with a uniform and a tapered manifold is undertaken. Applicability of the homogeneous model is evaluated using seven different viscosity averaging schemes. Experiments were performed with two test sections (one plain and one with open microchannels) and with four different manifolds (one uniform and three tapered). All experimental data with various configurations were compared with the different viscosity models. The viscosity model of Owen et al. predicted the highest value of pressure drop, while the lowest value was obtained with that of Dukler et al. All models underpredicted for uniform manifold with plain and microchannel chips with an average MAE of 50%. For tapered manifolds, plain chip underpredicted, while good agreement was obtained with microchannel chip for McAdams et al. and Akers et al.
A Modular Microfluidic System for High Flow Rate Re-Dispersion of Gas-Liquid
Authors: Tollkoetter Alexander , Kockmann Norbert
Published: December 2014

The application of microchannels is often limited in high-flow-rate processes due to large pressure losses. The flow of microbubbles in millichannels offers a reduced pressure loss with simultaneous large specific contact surface. Hence, a combination of micro- and millistructured channels termed as multi-scale architecture is an alternative scale-up procedure beside numbering-up or equaling-up. Several methods exist generating primary micro dispersions, while bubble coalescence in the channels has a contrary effect. A continuous re-dispersion by flow through micro nozzles prevents this effect. The transformation of pressure into kinetic energy creates an aimed secondary flow. Differences in velocity and pressure act on the phase boundary of the bubbles and lead to deformation and break-up. In this work, a modular redispersion system with different nozzle and channel modules is studied experimentally and by CFD simulations. Each module consists of micro nozzles and channels with a width from 0.1 to 3.0 mm. The design of the modules is flexible to be adjusted to process demands with different nozzles or channel structures. The effect of the nozzle dimensions on bubble sizes are evaluated for hydraulic diameters of 0.1 to 0.5 mm. Different channel structures are analyzed to offer less coalescence and a narrow residence time distribution. The modules are arranged in a holder and are fixed under a glass plate for optical characterization. Volume flow rates from 10 to 500 mL min−1 are studied with various phase ratios. Bubble diameters are generated in the range from 0.1 to 0.7 mm with narrow size distributions dependent on the entire flow rate through the device. Pressure losses account for less than 2 bar. Generally, a linear relation of smaller bubble diameters with larger energy input was identified. Flow detachment in curves resulted in larger coalescence rates, which was avoided by smoother radii.
Experimental Study on Two-Phase Pressure Drop of Air-Water in Horizontal Mini Channel
Authors: Engineer Ravi S. , Mehta Hemant B.
Published: December 2014

The new correlation for two-phase pressure drop for mini channel is developed by performing experiment on adiabatic two-phase pressure drop in mini channel with 3.1 mm diameter. Air-water mixture is used as the working substance. 180°-90°-90° (straight flow) test sections made of transparent glass tubes of 3.1 mm diameter with lengths of 900 mm. The superficial velocity varies from 0.2238 m/s to 1.1876 m/s for liquid (UL) and air (UG). Two phase flow pressure drop experiment is divided into two parts. First single phase pressure drop for air and water is experimented. The diameter is verified by measuring pressure drop of the air. Single phase pressure drop for air and water is experimented first which is followed by two phase pressure drop in the same mini channel. The existing correlations for macro and mini-channels are compared with the experimental data. Using Matlab & Minitab; a new correlation has been developed to predict two-phase pressure drop in horizontal mini channels.
Comparison of surface vacuum ultraviolet emissions with resonance level number densities. II. Rare-gas plasmas and Ar-molecular gas mixtures
Authors: Boffard John B. , Lin Chun C. , Wang Shicong , Wendt Amy E. , Culver Cody , Radovanov Svetlana , Persing Harold
Published: December 2014

Vacuum ultraviolet (VUV) emissions from excited plasma species can play a variety of roles in processing plasmas, including damaging the surface properties of materials used in semiconductor processing. Depending on their wavelength, VUV photons can easily transmit thin upper dielectric layers and affect the electrical characteristics of the devices. Despite their importance, measuring VUV fluxes is complicated by the fact that few materials transmit at VUV wavelengths, and both detectors and windows are easily damaged by plasma exposure. The authors have previously reported on measuring VUV fluxes in pure argon plasmas by monitoring the concentrations of Ar(3p54s) resonance atoms that produce the VUV emissions using noninvasive optical emission spectroscopy in the visible/near-infrared wavelength range [Boffard et al., J. Vac. Sci. Technol., A 32, 021304 (2014)]. Here, the authors extend this technique to other rare-gases (Ne, Kr, and Xe) and argon-molecular gas plasmas (Ar/H2, Ar/O2, and Ar/N2). Results of a model for VUV emissions that couples radiation trapping and the measured rare-gas resonance level densities are compared to measurements made with both a calibrated VUV photodiode and a sodium salicylate fluorescence detection scheme. In these more complicated gas mixtures, VUV emissions from a variety of sources beyond the principal resonance levels of the rare gases are found to contribute to the total VUV flux.
Formation of PtSi Schottky barrier MOSFETs using plasma etching
Authors: Woo Young Min , Hwang Wan Sik , Yoo Won Jong
Published: December 2014

PtSi Schottky barrier (SB) MOSFETs were fabricated and their device performance was characterized. PtSi was selected instead of NiSi to form the p-type SB junction since such a configuration would be easy to fabricate through SF6 based plasma etching. The addition of He-O2 in SF6 decreases the etching rate of PtSi while the etching rate of Pt remains unchanged. The retardation in the etching rate of PtSi in He-O2/SF6 is attributed to the formation of a metal oxide on the etched PtSi surface, as evidenced by the x-ray photoelectron spectroscopy results. Optical emission spectroscopy was conducted to establish the endpoint where the wavelength from the feed gas was traced instead of tracing the etching by-products since the by-products have little association with the plasma reaction. The IDS–VDS curves at various VG–VTH indicate that plasma etching resulted in the successful removal of the Pt on the sidewall region, with negligible damage to the S/D area.
Reading Plato for the 21st Century
Authors: Elgersma Helleman Wendy
Published: December 2014

Plato has received his share of bad press in this century. A number of significant schools of thought, like existentialism and phenomenology, have openly expressed impatience with Platonic ‘essentialism.’ He has even been blamed for fascism. Perhaps the problem goes back to Nietzsche’s call, at the turn of the century, to be true to the earth, our common mother. His message was aimed at otherworldly, pious Christians who, with a spiritualism worthy of the Platonists, regarded contemplative thought as the way to truth. Like a doubleedged sword Nietzsche’s call was also directed against metaphysics, dogmatism and intellectualism, the fruits of which he confronted in the weighty tomes for which German scholars then were justifiably renowned. It is not surprising that in the Soviet empire, built on Marxist-Leninist atheism, Nietzsche’s words fell on receptive ears. Not only were philosophers who dared openly to identify themselves as ‘Platonist’ or ‘idealist’ banned, exiled or executed. The teaching of classical antiquity, too, was almost entirely removed from the curriculum; the ancients could be considered only from a highly restricted point of view, via Democritus, Lucretius, or Aristotle.
Conditional Receptivity to Citizen Participation
Authors: Meng Tianguang , Pan Jennifer , Yang Ping
Published: December 2014

An increasing number of scholars have established that authoritarian regimes employ quasi-democratic institutions as part of their efforts to retain power. However, we know little about the potential variation among institutions providing citizens with opportunities for voice and the conditions under which such institutions are true channels of responsiveness. In this article, we develop and test the concept of “receptivity,” that is, whether autocrats are willing to incorporate citizen preferences into policy, using a list experiment of 1,377 provincial-and city-level leaders in China. Contrary to expectation, we find that leaders are similarly receptive to citizen suggestions obtained through either formal institutions or the Internet unless they perceive antagonism between the state and citizens, in which case receptivity to input from the Internet declines, while receptivity to formal institutions remains unchanged. Our findings show that whether quasi-democratic institutions are mere window dressing or true channels of responsiveness depends on the perceived quality of state–society relations.
Nuanced understandings of privatization in local authorities’ services to schools
Authors: Boyask Ruth
Published: December 2014

This article draws upon findings from the New Relations between Local Authorities (LAs) and Schools project to identify ideological and value-based differences between the models of service to schools adopted within four case study LAs. While each of the LAs has developed a privatized model of service, there are subtle differences between the models, which I term cooperative, entrepreneurial, community engagement and corporate. In this article I describe the differences between these models, and their underpinning values.
Potential Impact of Subsequent Entry Biologics in Nephrology Practice in Canada
Authors: Martinusen Daniel J , Lo Clifford , Marin Judith G , Tsao Nicole W , Leung Marianna
Published: December 2014

Purpose of review:

Subsequent entry biologics may soon be a reality in Canadian nephrology practice. Along with opportunities to reduce health care costs, these agents pose unique challenges that must be met for successful implementation. Understanding the experiences around the globe in both regulatory affairs and implementation will be a valuable guide for Canadian clinicians. This report provides an executive summary of the information required to guide decisions to use or implement subsequent entry biologics by comparing Canadian regulations to other developed nations, discussing their clinical issues and predicting their impact on the Canadian market and nephrology practice. We hope that this review will assist clinicians and policy makers to navigate this complex subject and to make informed decisions in the best interest of their patients.

Sources of information:

Sources of information include published literature and reports available in the public domain including guidelines obtained from regulatory agencies and information shared by Pharmaceutical companies. Lastly, we generated information from our own focus group consisting of nephrologists, a regulatory body representative, a hospital formulary representative, a patient representative, a hospital administrator, and a health economist.

Findings:

There exists a common and robust approach in the G20 countries for approval and regulation of subsequent entry biologics. Although by definition these agents do not have advantages (other than costs) or disadvantages compared to the original biologic, there are potential concerns and economic uncertainties regarding their implementation. Where SEBs are on the market, their market share is variable and modest.

Limitations:

We did not purchase third party reports for up to the minute marketing data. Since there are no subsequent entry biologics currently on the Canadian market, the information is only predictive.

Implications:

The nephrology community will have to work with patients, payers, and regulatory bodies to ensure safe and effective use of subsequent entry biologics. Cost savings can be achieved but these agents should only be used after fully understanding their unique challenges. At this time, they should not be automatically substitutable and only used for Health Canada-approved indications. Only through good pharmacovigilence will health care providers and patients become better informed.
Field Tests and Numerical Modeling of Vehicle Impacts on a Boulder Embedded in Compacted Fill
Authors: Reese Lynsey , Qiu Tong , Linzell Daniel , O'Hare Edward , Rado Zoltan
Published: December 2014

Landscape Vehicular Anti-Ram (LVAR) systems are a group of protective barriers, which are designed using natural materials (e.g., boulders) and have proven to both effectively protect sensitive structures against threats and be aesthetically pleasing. This paper presents two consecutive vehicular crash tests hitting the same single boulder embedded in AASHTO coarse aggregate fill. A LS-DYNA model was developed to simulate the field-scale tests, which were instrumented with high-speed cameras and pressure cells. A readily available truck model from the National Crash Analysis Center was modified and implemented in the LS-DYNA model. The boulder and surrounding soil were modeled using the Mohr-Coulomb failure criteria. The model parameters were calibrated using results from the first field-scale test with a truck traveling at 48.3 km/hr (30 mph) impacting the LVAR system. The calibrated model was then used to simulate the second field-scale test, which involved a truck traveling at 80.5 km/hr (50 mph) impacting the same LVAR system without resetting the boulder or soil. The calibrated model was able to provide the global response of the system, including the time-history of the translational displacement and rotation of the boulder, and was in good agreement with field-scale test results. This suggests that the overall global response was dominated by the dynamic behavior of the truck and boulder system upon impact. Hence, a simple material model for soil and boulder is sufficient for simulating the tests conducted.
Impact of Aircraft Wing against World Trade Center Columns
Authors: Szuladziński Gregory
Published: December 2014

The problem of interest is the collision between the wing of the aircraft and the WTC columns. This is quantified in two ways: by an analytical method and by FEA simulation. The first involved simple static and somewhat more complex dynamic patterns. The FEA approach used moderate size models, which had some features not employed before. The real question behind this work was if a significant amount of fuel was necessary in the wing to make it cut the columns. The question is answered by conducting the analyses for the outboard part of the wing that had rather thin skin, 4 and 2 mm respectively and negligible fuel content.
Contribuição para o Conhecimento da Fauna de Arctiinae (Lepidoptera: Erebidae) no Estado de Santa Catarina, Brasil
Authors: Silva Janaína Madruga , Silva Eduardo José Ely
Published: December 2014

Com o objetivo de contribuir para o conhecimento da fauna de Arctiinae (Lepidoptera: Erebidae) ocorrentes no Estado de Santa Catarina, elaborou-se uma lista das espécies depositadas no Museu Entomológico Ceslau Biezanko. Os dados são referentes a coletas realizadas na região entre os anos 1943 e 1976 por Ceslau Maria Biezanko, Vitor Becker e Fritz Plauman. Foram encontradas 101 espécies, distribuídas em 57 gêneros e 238 indivíduos de Arctiini. Um total de 15 espécies é novo registro para o estado.

Contribution to the Knowledge of the Arctiinae (Lepidoptera: Erebidae) Fauna in the Santa Catarina State, Brazil

Abstract. Aiming to contribute to the knowledge of the Arctiinae (Lepidoptera: Family: Erebidae) fauna occurring in the Santa Catarina State, drew up a list of species deposited in the Entomological Museum Ceslau Biezanko. The data relating to collections made in the region between 1943 and 1976 by Maria Ceslau Biezanko, Vitor Becker and Fritz Plauman. We found 101 species in 57 genera and 238 individuals of Arctiini. A total of 15 species are new record for the state.
Primeira Reportagem da Mosca Minadora em Cebola no Alto Paranaíba
Authors: Alves Flávia , Fernandes Flávio , Silva Paulo , Gorri Jéssica , Ribeiro Luan
Published: December 2014

Liriomyza spp. é considera praga em várias culturas no Brasil. As larvas confeccionam minas nas folhas, reduzem a área fotossintética, causam murcha e queda precoce de folhas. Objetivou-se neste trabalho reportar o primeiro ataque de Liriomyza spp., seu dano e a sobrevivência em cebola (Allium cepa L.) no Alto Paranaíba-MG. A sua ocorrência e o prejuízo foram detectados em cinco avaliações em 12 lavouras de cebola (50 plantas/ha). Já a sobrevivência foi determinada em condições de temperatura controlada. Observou-se a presença de Liriomyza spp. causando minas serpenteadas, com relação direta e negativa do número de minas com a produtividade, com prejuízo de 120 kg ha-1 e com taxa de sobrevivência de larva-pupa (57,89%) e pupa-adulto (63,63%). Este fitófago pode se tornar praga séria nesta cultura.

First Occurrence of Leafminer Causing Damage in Onion at Alto Paranaíba

Abstract. Liriomyza spp. is considered pests in various crops in Brazil. The larvae mine the leaves cook up, reduce the photosynthetic area, cause wilting and premature leaf drop. The objective of this study report the first attack of Liriomyza spp., its damage and survival in onion (Allium cepa L.) in Alto Parnaíba-MG. Their occurrence and injury ratings were detected in five of onion crops in 12 (50 plants/ha). Since survival was determined under conditions of controlled temperature. We observed the presence of Liriomyza spp. causing serpentine mines, with direct and negative relationship with the number of mines productivity, a loss of 120 kg ha-1 and survival rate of larva-pupa (57.89%) and pupa-adult (63.63%). Thus, this phytophagous insect can become a serious pest in this crop.
The Metapleural Secretion of Acromyrmex laticeps (Forel) does not have Fungicide Effect on the Entomopathogenic Fungus Beauveria bassiana (Bals.) Vuill
Authors: Junqueira Luciane Kern , Diehl Elena
Published: December 2014

The metapleural gland (MPG) is an exocrine structure, exclusive to formicids, being more developed in females and workers. This structure is stunted or nonexistent in males. Several possible functions for the secretion produced by this gland have been suggested, but a protection against entomopathogens is the most accepted hypothesis. To test this, we applied a suspension of spores (1.30 x 106) of Beauveria bassiana (Bals.) Vuill. on the MPG and the antero-superior portion of the metathorax (ASM) of winged females of Acromyrmex laticeps (Forel). We only applied the suspension in the ASM of males, since they do not have the atrium characteristic in the MPG. Our results indicated that the metapleural secretion of females has no fungicidal effect on B. bassiana, and therefore both males and winged females are sensitive to this entomopathogenic fungus.

Ausência de Efeito Fungicida da Secreção Metapleural de Acromyrmex laticeps (Forel) Contra Beauveria bassiana (Bals.) Vuill.

Resumo. A glândula metapleural (GMP) é uma estrutura exógena, encontrada apenas nos formicídeos, sendo mais desenvolvida nas fêmeas e operárias, enquanto nos machos ou está atrofiada ou não existe. Tem sido sugerido várias possíveis funções para a secreção produzida por esta glândula, sendo a hipótese de efeito protetor contra entomopatógenos a mais estudada. Para testar esta hipótese, foi aplicada uma suspensão de conídios (1,30 x 106) de Beauveria bassiana (Bals.) Vuill. nas GMP e na porção ântero-superior do metatórax (ASM) de fêmeas aladas de Acromyrmex laticeps (Forel), enquanto nos machos a suspensão foi aplicada apenas na porção ASM, pois estes não apresentam o átrio característico da GMP. Os resultados obtidos indicaram que a secreção metapleural das fêmeas desta espécie não possui efeito fungicida sobre B. bassiana, e que tanto os machos como as fêmeas alados são sensíveis a este fungo entomopatogênico.