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High Responsivity and Photovoltaic Effect Based on Vertical Transport in Multilayer α-In2Se3
No full textHerein, device demonstration based on vertical transport in multilayer α-In2Se3 is reported. Photodetectors realized using a metal/α-In2Se3/indium tin oxide (ITO) vertical junction exhibit clear signature of the band edge in spectral responsivity. The wavelength at 680 nm corresponding to an ultrahigh responsivity of 1000 A W�1 and a detectivity of >1013 cm Hz0.5 W�1 at a bias of 0.5 V. The variation of responsivity and detectivity with optical power density is studied, and a transient response of 20 ms is obtained for the devices (instrument limitation). In addition, an asymmetric barrier height arising out of ITO and Au contacts to a vertical α-In2Se3 junction resulted in a photovoltaic effect with VOC �0.1 V and ISC �0.4 μA under an illumination of 520 nm
Robust emergence of sharply tuned place-cell responses in hippocampal neurons with structural and biophysical heterogeneities
No full textHippocampal pyramidal neurons sustain propagation of fast electrical signals and are electrotonically non-compact structures exhibiting cell-to-cell variability in their complex dendritic arborization. In this study, we demonstrate that sharp place-field tuning and several somatodendritic functional maps concomitantly emerge despite the presence of geometrical heterogeneities in these neurons. We establish this employing an unbiased stochastic search strategy involving thousands of models that spanned several morphologies and distinct profiles of dispersed synaptic localization and channel expression. Mechanistically, employing virtual knockout models (VKMs), we explored the impact of bidirectional modulation in dendritic spike prevalence on place-field tuning sharpness. Consistent with the prior literature, we found that across all morphologies, virtual knockout of either dendritic fast sodium channels or N-methyl-d-aspartate receptors led to a reduction in dendritic spike prevalence, whereas A-type potassium channel knockouts resulted in a non-specific increase in dendritic spike prevalence. However, place-field tuning sharpness was critically impaired in all three sets of VKMs, demonstrating that sharpness in feature tuning is maintained by an intricate balance between mechanisms that promote and those that prevent dendritic spike initiation. From the functional standpoint of the emergence of sharp feature tuning and intrinsic functional maps, within this framework, geometric variability was compensated by a combination of synaptic democracy, the ability of randomly dispersed synapses to yield sharp tuning through dendritic spike initiation, and ion-channel degeneracy. Our results suggest electrotonically non-compact neurons to be endowed with several degrees of freedom, encompassing channel expression, synaptic localization and morphological microstructure, in achieving sharp feature encoding and excitability homeostasis
Influence of cations on optical properties of iodobismuthates
No full textSynthesis of iodobismuthates and tuning their properties attracted a lots of attention due to their contribution in developing opto-electronic devices. Two 1-D polymeric iodobismuthate compounds, 2,6-(NH2)2PyHBiI4n (1), 4-NMe2PyHBiI4n (2), Py: Pyridine have been reported, where structurally similar polymeric anionic iodobismuthate is stabilised by two different pyridinium cations namely 2,6-bis(amino)pyridine and 4-(N,N-dimethylamino)pyridine derivatives. The compounds have been characterised by single crystal XRD, IR and elemental analysis. It is interesting to observe that the structurally similar compounds differ drastically in their optical properties because of slight variation in the cations. Comparison in structural features and their thermal, optical properties (band gap: 1.91 eV (1); 2.10 eV (2)) have been discussed. Thermochromism is exhibited by 1. DFT studies of compound 1 has been performed considering the crystal structure measured at two different temperature and the role of cation in tuning the optical properties of iodobismuthates has been established
Obesity-induced sympathoexcitation is associated with Nrf2 dysfunction in the rostral ventrolateral medulla
No full textIncreases in sympathetic nerve activity (SNA) have been implicated in obesity-induced risk for cardiovascular diseases, especially hypertension. Previous studies indicate that oxidative stress in the rostral ventrolateral medulla (RVLM), a key brain stem region that regulates sympathetic outflow to peripheral tissues, plays a pathogenic role in obesity-mediated sympathoexcitation. However, the molecular mechanisms underlying this phenomenon are not clear. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates the expression of antioxidant and anti-inflammatory genes and confers cytoprotection against oxidative stress. The present study was designed to investigate whether Nrf2 dysfunction was associated with obesity-induced oxidative stress in the RVLM and sympathoexcitation. C57BL/6J mice were fed with chow or a high-fat diet (HFD) for 16 wk. Blood pressure parameters were assessed by radiotelemeters in conscious freely moving mice. SNA was measured by heart rate variability analysis and also through assessment of depressor response to ganglionic blockade. The RVLM was microdissected for gene expression and protein analysis (Western blot analysis and activity assay) related to Nrf2 signaling. Our results showed that HFD-induced obesity resulted in significant increases in SNA, although we only observed a mild increase in mean arterial pressure. Obesity-induced oxidative stress in the RVLM was associated with impaired Nrf2 signaling marked by decreased Nrf2 activity, downregulation of Nrf2 mRNA, its target genes NAD(P)H quinone dehyrogenase 1 (Nqo1) and superoxide dismutase 2 (Sod2), and inflammation. Our findings suggest that obesity results in Nrf2 dysfunction, which likely causes maladaptation to oxidative stress and inflammation in the RVLM. These mechanisms could potentially contribute to obesity-induced sympathoexcitation
Electric current driven formation of micro-and nano-sized beads in thin Cr films
No full textNano films of chromium with thicknesses from 20 to 200 nm were deposited on silicon substrates and were treated by electric current induced by AFM tip in ambient atmosphere. The melting on the nanoscale, electric current induced migration of the material and chemical reaction of oxidization of chromium were revealed in melting craters around the point of application of the current by optical and electronic scanning microscopy, AFM, and Raman spectroscopy. The flow of the material induced by electric current is accompanied by formation and motion of the matrix of the spherical nanoparticles (beads) in the crater of melt on its periphery. The reaction of chromium oxidation and surface tension of the melted material on the silicon substrate are expected to be responsible for the matrix of nano beads formation under comparatively small currents. Raman spectroscopy confirms that in the vicinity of the periphery of the melted craters around AFM tip application, the beads of oxide phase Cr2O5 are present
Ultrasonic guided wave scattering due to delamination in curved composite structures
No full textWave propagation in a curved composite structure having delamination is simulated using time domain spectral finite element (TSFE) method that enables fast computation with higher-order field interpolation. Curved structures are very common in aerospace, marine and other composite structural components and understanding ways to detect delamination in these curved structures with the help of ultrasonic guided wave simulation is essential. Guided wave interaction with curved region progressively causes mode converted waves, which are present in both reflected as well as transmitted wave packets. The details are poorly understood. The additional wave packets due to interaction cause difficulty in identification of damaged induced responses. Mode conversion and reflection from the curved section reduce the useful signal strength to interrogate any delamination in the curved region. Guided wave interaction with the curved section in an L-shaped structure and a structure with T-joint are studied using TSFE simulation. Simulation results are validated using analytical solutions. Mode conversion and transmission in T-joint is studied using numerical simulation with experimental validation. Signal loss due to mode conversion and reflections at different frequencies is investigated in terms of geometric and wave parameters, which promises to identify the appropriate frequencies and choice of wave mode for monitoring
Elemental partitioning in medium Mn steel during short-time annealing: An in-situ study using synchrotron x-rays
No full textIn this study, high energy synchrotron radiation was used to perform an in-situ diffraction experiment in medium Mn Fe-6Mn-0.5C-1Al alloy to study the elemental partitioning and consequent austenite phase evolution at different stages, namely, during heating, holding and cooling. It has been observed that the austenite phase fraction significantly increases on annealing at the inter-critical annealing temperature and remains stable at room temperature. The austenite phase stability at room temperature is due to the rapid partitioning of manganese (Mn) and carbon (C) during annealing. The relative change in d-spacing (�d/d) during heating-cooling confirms the partitioning of alloying elements during inter-critical annealing. © 202
Identification and characterization of two conserved G-quadruplex forming motifs in the Nipah virus genome and their interaction with G-quadruplex specific ligands
No full textThe G-quadruplex (GQ) motifs are considered as potential drug-target sites for several human pathogenic viruses such as Zika, Hepatitis, Ebola, and Human Herpesviruses. The recent outbreaks of Nipah virus (NiV) in India, the highly fatal emerging zoonotic virus is a potential threat to global health security as no anti-viral drug or vaccine in currently available. Therefore, here in the present study, we sought to assess the ability of the putative G-quadruplex forming sequences in the NiV genome to form G-quadruplex structures and act as targets for anti-viral compounds. Bioinformatics analysis underpinned by various biophysical and biochemical techniques (such as NMR, CD, EMSA, DMS footprinting assay) confirmed the presence of two highly conserved G-quadruplex forming sequences (HGQs) in the G and L genes of NiV. These genes encode the cell attachment glycoprotein and RNA-dependent RNA polymerase, respectively and are essential for the virus entry and replication within the host cell. It remains possible that stabilization of these HGQs by the known G-quadruplex binding ligands like TMPyP4 and Braco-19 represents a promising strategy to inhibit the expression of the HGQ harboring genes and thereby stop the viral entry and replication inside the host cell. Accordingly, we report for the first time, that HGQs in Nipah virus genome are targets for G-quadruplex specific ligands; therefore, could serve as potential targets for anti-viral therapy
Forest working plan for the sustainable management of forest and biodiversity in India
No full textForests are one of the major sources of livelihood that need to be conserved. In India, there have been continuous efforts to evolve a scientific basis for sustainable management of forests. In recent century, this has primarily been addressed through ``forest management plans,'' also known as ``working plans.'' To make the plans uniform for each of the forest management units, guidelines have been issued by Government of India in the name of ``working plan code,'' which are revised periodically to match present days' requirement. A working plan largely deals with the present state of the forest, outcomes of past management, and proposal of future management on a scientific basis. With a significant lapse of time, the role of forests has been recognized beyond mere supply of timber (a major resource) to fulfilling the demands of minor resources and ecological services. This has transformed the basis of forest management and the working plans. With reference to India, we discuss the relevance of working plan for sustainable management of forests; highlights of the most recent working plan code (2014); relevance of the code with reference to climate change and biodiversity, future perspectives, and recommendations for better management of the forests
Effect of LaNiO3 on the impedance and dielectric properties of CoFe2O4: a high temperature study
No full textIn this article, we report the impedance and dielectric properties of the nanocomposites comprising of CoFe2O4 (CFO) and LaNiO3 (LNO) with varying LNO content (0, 5, 10 and 15%) in the temperature range from 35 degrees C-400 degrees C. The impedance and modulus spectroscopy show the non-Debye type dielectric relaxation behaviour of the grain and grain boundary separately in pure CFO with an additional relaxation in the composite with 15% LNO, arising from the electrode polarization. Mostly the grain boundary of the composites is affected by the presence of LNO as its activation energy in the composite with 15% LNO is reduced by similar to 0.2-eV compared to pure CFO, whereas that of the grain remains similar. The dielectric constant increases consistently with increasing LNO content in the composites owing to the Maxwell-Wagner-Sillar type polarization effect between the interfaces of LNO and CFO. The dielectric constant manifests a negative value in both pure CFO and the composite with 15% LNO at all temperatures in the frequency of hundreds of MHz which is explained by the interband transition. The ac conductivity of pure CFO reveals short range and orientational hopping inside the grains and across the grain boundary, respectively. However, in the composite with 15% LNO, the reduced activation energy assists the charge carriers for short range hopping across the grain boundary while the conductivity inside the grain remains unaffected