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Analysis of electronic parameters and frequency-dependent properties of Au/NiO/n-GaN heterojunctions
No full textThe electrical and frequency-dependent properties of ten Au/NiO/n-GaN heterojunctions fabricated with similar conditions are assessed by I-V, C-V, and G-V measurement methods. In addition, C-f and G-f measurements are conducted in the frequency range of 1 kHz-1 MHz. The electronic parameters are changed from junction to junction even if they are fabricated in the similar way. The calculated barrier height and ideality factor values are fitted by the Gaussian distribution function. Statistical analysis of the data provides the mean barrier height and ideality factor values of 0.84 eV and 2.70 for the heterojunction. Besides, the mean barrier height (Phi(b)), donor concentration (N-d), space charge layer width (W-D), and Fermi level (E-F) are determined from the C-V data and the corresponding values are 1.30 eV, 2.00x 10(17) cm(-3), 8.222 x 10(-6) cm, and 0.018 eV, respectively. The interface state density (N-SS) and relaxation time (tau) are assessed from C-f and G-f measurements. Moreover, the dielectric constant (epsilon'), dielectric loss (epsilon `'), tangent loss (tan delta), and electrical conductivity (sigma(ac)) are determined from C-f and G-f data in the frequency range of 1 kHz-1 MHz with various biases (0.1-0.6 V). epsilon' and epsilon `' are decreased with increasing frequency
Understanding the unusual photoluminescence properties of SiOx nanoropes prepared by thermal evaporation method
No full textWe report the indium oxide catalyzed growth of the amorphous SiOx nanoropes using the silicon wafer as both source-cum-substrates by thermal evaporation and investigate the luminescence properties. Both blue and yellow emissions are observed from the nanoropes. Blue emission could be attributed to the defect centers of the oxygen deficiency in the nanoropes, whereas yellow emission is due to the trapped excitons in the Si/SiOx interface of the materials. Effect of laser exposure on luminescence properties is studied by performing time-dependent PL measurements at different ambiance. Irrespective of laser excitation and ambiance, a monoexponential decay of blue emission with continuous laser exposure is clearly observed, which is due to the gradual removal of surface adsorbed species
Burden of Dilated Perivascular Spaces, an Emerging Marker of Cerebral Small Vessel Disease, Is Highly Heritable
No full textBackground and Purpose-The genetic contribution to dilated perivascular space (dPVS) burden-an emerging MRI marker of cerebral small vessel disease-is unknown. We measured the heritability of dPVS burden and its shared heritability with other MRI markers of cerebral small vessel disease. Methods-The study sample comprised 1597 participants from the population-based Three City (3C) Dijon Study, with brain MRI and genome-wide genotyping (mean age, 72.8 +/- 4.1 years; 61% women). dPVS burden and lacunar brain infarcts were rated on a semiquantitative scale, whereas an automated algorithm generated white matter hyperintensity volume (WMHV). We estimated dPVS burden heritability and shared heritability with WMHV and lacunar brain infarcts using the genome-wide complex trait analysis tool, on unrelated participants, adjusting for age, sex, intracranial volume, and principal components of population stratification. Results-dPVS burden was significantly correlated with WMHV and lacunar brain infarcts, the strongest correlation being found between WMHV and dPVS in basal ganglia. Heritability estimates were h(2) = 0.59 +/- 0.24 (P = 0.007) for dPVS burden, h(2) = 0.54 +/- 0.24 (P = 0.010) for WMHV, and h(2) = 0.48 +/- 0.81 (P = 0.278) for lacunar brain infarcts. We found a nonsignificant trend toward shared heritability between dPVS and WMHV (r(g) = 0.41 +/- 0.28; P = 0.096), which seemed driven by dPVS in basal ganglia (r(g) = 0.72 +/- 0.61; P= 0.126) and not dPVS in white matter (r(g) =-0.10 +/- 0.36; P = 0.393). A genetic risk score for WMHV based on published loci was associated with increased dPVS burden in basal ganglia (P = 0.031). Conclusions-We provide evidence for important genetic contribution to dPVS burden in older community-dwelling people, some of which may be shared with WMHV. Differential heritability patterns for dPVS in white matter and basal ganglia suggest at least partly distinct underlying biological processes
A beta mediates F-actin disassembly in dendritic spines leading to cognitive deficits in Alzheimer's disease
No full textDendritic spine loss is recognized as an early feature of Alzheimer's disease (AD), but the underlying mechanisms are poorly understood. Dendritic spine structure is defined by filamentous actin (F-actin) and we observed depolymerization of synaptosomal F-actin accompanied by increased globular-actin (G-actin) at as early as 1 month of age in a mouse model of AD(APPswe/PS1 Delta E9, male mice). This led to recall deficit after contextual fear conditioning (cFC) at 2 months of age in APPswe/PS1 Delta E9 male mice, which could be reversed by the actin-polymerizing agent jasplakinolide. Further, the F-actin-depolymerizing agent latrunculin induced recall deficit after cFC in WT mice, indicating the importance of maintaining F-/G-actin equilibrium for optimal behavioral response. Using direct stochastic optical reconstruction microscopy (dSTORM), we show that F-actin depolymerization in spines leads to a breakdown of the nano-organization of outwardly radiating F-actin rods in cortical neurons from APPswe/PS1 Delta E9 mice. Our results demonstrate that synaptic dysfunction seen as F-actin disassembly occurs very early, before onset of pathological hallmarks in AD mice, and contributes to behavioral dysfunction, indicating that depolymerization of F-actin is causal and not consequent to decreased spine density. Further, we observed decreased synaptosomal F-actin levels in postmortem brain from mild cognitive impairment and AD patients compared with subjects with normal cognition. F-actin decrease correlated inversely with increasing AD pathology (Braak score, A beta load, and tangle density) and directly with performance in episodic and working memory tasks, suggesting its role in human disease pathogenesis and progression
Insights to bioprocess and treatment competence of urban wetlands
No full textWetlands play a major role in the recharge of groundwater resources, maintenance of water quality (remediation), moderate microclimate while supporting local livelihood through provision of fish, fodder, etc. The present study aims to investigate algal-bacterial consortium as a function of residence time with the water quality dynamics in two major wetlands in Bangalore city, India. Over thirty-two genera of algae were recorded with more than 40 species in the lakes and two dominant bacterial assemblages. The higher Ammonium-N content favoured the growth of these members. Significant correlation was observed between the nutrient concentrations and the community structure at the inflows and the outflows. The algal community showed negative correlation to filterable COD and high nutrients levels while bacterial abundance was observed under high loadings. The green algae Chlorophyceae (Chlorella blooms), which are indicators of nutrient enrichment were observed predominantly, that needs an immediate attention. Higher overall treatment efficiency was observed in terms of CNP removal during the Pre-monsoon season attributed to absence of macrophytes cover and rapid growth of algal assemblage's due to higher temperature regimes with adequate solar insolation. (C) 2017 Elsevier Ltd. All rights reserved
Quantification of annual sediment deposits for sustainable sand management in Aghanashini river estuary
No full textSedimentation involving the process of silt transport also carries nutrients from upstream to downstream of a river/stream. Sand being one of the important fraction of these sediments is extracted in order to cater infrastructural/housing needs in the region. This communication is based on field research in the Aghanshini river basin, west coast of India. Silt yield in the river basin and the sedimentation rate assessed using empirical techniques supplemented with field quantifications using soundings (SONAR), show the sediment yield of 1105-1367 kilo cum per year and deposition of sediment of 61 (2016) to 71 (2015) cm. Quantifications of extractions at five locations, reveal of over exploitation of sand to an extent of 30% with damages to the breeding ground of fishes, reduced productivity of bivalves, etc., which has affected dependent people's livelihood. This study provides vital insights towards sustainable sand harvesting through stringent management practices. (C) 2017 Elsevier Ltd. All rights reserved
Pseudorapidity distributions of charged hadrons in proton-lead collisions at root s(NN)=5:02 and 8.16 TeV
No full textThe pseudorapidity distributions of charged hadrons in proton-lead collisions at nucleon-nucleon center-of-mass energies root s(NN) = 5.02 and 8.16 TeV are presented. The measurements are based on data samples collected by the CMS experiment at the LHC. The number of primary charged hadrons produced in non-single-diffractive proton-lead collisions is determined in the pseudorapidity range vertical bar eta(lab)vertical bar < 2.4. The charged-hadron multiplicity distributions are compared to the predictions from theoretical calculations and Monte Carlo event generators. In the center-of-mass pseudorapidity range vertical bar eta(cm)vertical bar < 0.5, the average charged-hadron multiplicity densities < dN(ch)/d eta(cm)>vertical bar(vertical bar eta cm vertical bar) < 0.5 are 17.1 +/- 0.01 (stat) +/- 0.59 (syst) and 20.10 +/- 0.01 (stat) +/- 0.5(syst) at root s(NN) = 5.02 and 8.16 TeV, respectively. The particle densities per participant nucleon are compared to similar measurements in proton-proton, proton-nucleus, and nucleus-nucleus collisions
High Performance Parallel Single-Phase Converter Reconfiguration for Enhanced Availability
No full textParalleling power converters is a common practice in industries to enhance total power rating, reliability, and availability of the system. In case of fault occurring in systems with parallel converters, the faulty power converter can be isolated and the system can still be operated at reduced power level. In this paper, a grid-connected power converter consisting of two parallel H-bridge converters with low ground leakage current is considered. Two contingency configurations, that are also of low ground leakage current, are proposed to enhance the availability of the system. This is done by reconfiguring the power circuit to a single H-bridge in the case of failure in one of the bridges. The power converter is experimentally tested with the proposed configurations for experimental validation. The results show that the second configuration has better performance in terms of power loss and current total harmonic distortion when operating at lower power level
Determination of GMPE functional form for an active region with limited strong motion data: application to the Himalayan region
No full textAdvancement in the seismic networks results in formulation of different functional forms for developing any new ground motion prediction equation (GMPE) for a region. Till date, various guidelines and tools are available for selecting a suitable GMPE for any seismic study area. However, these methods are efficient in quantifying the GMPE but not for determining a proper functional form and capturing the epistemic uncertainty associated with selection of GMPE. In this study, the compatibility of the recent available functional forms for the active region is tested for distance and magnitude scaling. Analysis is carried out by determining the residuals using the recorded and the predicted spectral acceleration values at different periods. Mixed effect regressions are performed on the calculated residuals for determining the intra- and interevent residuals. Additionally, spatial correlation is used in mixed effect regression by changing its likelihood function. Distance scaling and magnitude scaling are respectively examined by studying the trends of intraevent residuals with distance and the trend of the event term with magnitude. Further, these trends are statistically studied for a respective functional form of a ground motion. Additionally, genetic algorithm and Monte Carlo method are used respectively for calculating the hinge point and standard error for magnitude and distance scaling for a newly determined functional form. The whole procedure is applied and tested for the available strong motion data for the Himalayan region. The functional form used for testing are five Himalayan GMPEs, five GMPEs developed under NGA-West 2 project, two from Pan-European, and one from Japan region. It is observed that bilinear functional form with magnitude and distance hinged at 6.5 M (w) and 300 km respectively is suitable for the Himalayan region. Finally, a new regression coefficient for peak ground acceleration for a suitable functional form that governs the attenuation characteristic of the Himalayan region is derived
Mechanism of formation of a toroid around DNA by the mismatch sensor protein
No full textThe DNA mismatch repair (MMR) pathway removes errors that appear during genome replication. MutS is the primary mismatch sensor and forms an asymmetric dimer that encircles DNA to bend it to scan for mismatches. The mechanism utilized to load DNA into the central tunnel was unknown and the origin of the force required to bend DNA was unclear. We show that, in absence of DNA, MutS forms a symmetric dimer wherein a gap exists between the monomers through which DNA can enter the central tunnel. The comparison with structures of MutS-DNA complexes suggests that the mismatch scanning monomer (B-m) will move by nearly 50 angstrom to associate with the other monomer (A(m)). Consequently, the N-terminal domains of both monomers will press onto DNA to bend it. The proposed mechanism of toroid formation evinces that the force required to bend DNA arises primarily due to the movement of B-m and hence, the MutS dimer acts like a pair of pliers to bend DNA. We also shed light on the allosteric mechanism that influences the expulsion of adenosine triphosphate from A(m) on DNA binding. Overall, this study provides mechanistic insight regarding the primary event in MMR i.e. the assembly of the MutS-DNA complex