50175 research outputs found
Sort by
Toward a Fast and Highly Responsive SnSe2-Based Photodiode by Exploiting the Mobility of the Counter Semiconductor
No full textIn photodetection, the response time is mainly controlled by the device architecture and electron/hole mobility, while the absorption coefficient and the effective separation of the electrons/holes are the key parameters for high responsivity. Here, we report an approach toward the fast and highly responsive infrared photodetection using an n-type SnSe2 thin film on a p-Si(100) substrate keeping the overall performance of the device. The I-V characteristics of the device show a rectification ratio of similar to 147 at +/- 5 V and enhanced optoelectronic properties under 1064 nm radiation. The responsivity is 0.12 A/W at 5 V, and the response/recovery time constants were estimated as similar to 57 +/- 25/34 +/- 15 mu s, respectively. Overall, the response times are shown to be controlled by the mobility of the constituent semiconductors of a photodiode. Further, our findings suggest that n-SnSe2 can be integrated with well-established Si technology with enhanced optoelectronic properties and also pave the way in the design of fast response photodetectors for other wavelengths as well
Conjugal transfer of erm(B) and multiple tet genes from Lactobacillus spp. to bacterial pathogens in animal gut, in vitro and during food fermentation
No full textThree strains of Lactobacillus comprising Lactobacillus salivarius (CHS-1E and CH7-1E) and Lactobacillus reuteri (CH2-2) previously isolated from chicken meat were analyzed for their transferability of antibiotic resistance (AR) genes to pathogenic strains under in vivo, in vitro, and during food fermentation. For in vivo model, Albino Wistar rats were inoculated with 10(10) CFU/g/ml of Enterococcus faecalis JH2-2 (recipient). After 7 days, either of two donors L. salivarius CH7-1E or L. reuteri harbouring erythromycin and tetracycline resistance genes] were introduced at a concentration of 10(9) CFU/ml daily for 1 week. Two days after donor introduction, there was a stable increase in the number of transconjugants in the animal faeces from 10(2) to 10(3)CFU/g and presented erm (B), tet(M), tet(L) and tet(W) in their genome like donor strains. Similar observations were made with in vitro filter mating between CHS-1E, CH2-2 and CH7-1E and E. faecalis JH2-2 with transfer frequencies of 1 x 10(-4), 3.8 x 10(-3) and 2 x 10(-3) per donor cell respectively. With the results obtained in vivo and in vitro, the AR transferability of donor strains was estimated during food fermentation (chicken sausage, fermented milk or idii batter) with pathogenic recipient strains added as contaminants. At the end of mating period, phenotypic resistance to erythromycin and tetracycline in Listeria monocytogenes and Yersinia enterocolitica strains was observed. This study showed the ability of food borne Lactobacillus in diffusing their AR traits in diverse natural environments increasing their concern of AR dissemination in the food chain when used as food additives and/or probiotics
Critical investigation on Cu-O bonding configuration variation in copper-oxide thin films for low-cost solar cell applications
No full textThe present work provides a detailed investigation on how Copper-Oxygen bonding configuration varies with the plasma processing parameters. XRD, FTIR, XPS and Raman spectroscopy is extensively used to identify and study the phases and phase changes in the films. The Copper-Oxygen bonding configuration was altered by varying the RF power and substrate temperature. We studied the combined effect of both RF power and substrate temperature on the Cu-O bonding configuration, which in turn affects the optical and electrical properties, which are essential to understand before the device fabrication. Films were deposited with 40, 60 and 80 W of RF power at the different growth temperatures such as RT(room temperature), 200 °C and 400 °C. Even the RT deposited films were found to be exhibiting the crystalline nature to the maximum extent. We observed a wide range of variation in the Cu-O bonding configurations with the RF power and growth temperature. Films deposited at 80 W are leaning towards Cu 2 O phase, whereas films deposited with 40 W is close to CuO phase. Also it is found that, for a fixed power, the films deposited at high substrate temperature are leaning towards Cu 2 O Phase. © 2019 Elsevier Lt
Luminescence- and Fluorescence-Based Complementation Assays to Screen for GPCR Oligomerization: Current State of the Art
No full textG protein-coupled receptors (GPCRs) have the propensity to form homo- and heterodimers. Dysfunction of these dimers has been associated with multiple diseases, e.g., pre-eclampsia, schizophrenia, and depression, among others. Over the past two decades, considerable efforts have been made towards the development of screening assays for studying these GPCR dimer complexes in living cells. As a first step, a robust in vitro assay in an overexpression system is essential to identify and characterize specific GPCR-GPCR interactions, followed by methodologies to demonstrate association at endogenous levels and eventually in vivo. This review focuses on protein complementation assays (PCAs) which have been utilized to study GPCR oligomerization. These approaches are typically fluorescence- and luminescence-based, making identification and localization of protein-protein interactions feasible. The GPCRs of interest are fused to complementary fluorescent or luminescent fragments that, upon GPCR di- or oligomerization, may reconstitute to a functional reporter, of which the activity can be measured. Various protein complementation assays have the disadvantage that the interaction between the reconstituted split fragments is irreversible, which can lead to false positive read-outs. Reversible systems offer several advantages, as they do not only allow to follow the kinetics of GPCR-GPCR interactions, but also allow evaluation of receptor complex modulation by ligands (either agonists or antagonists). Protein complementation assays may be used for high throughput screenings as well, which is highly relevant given the growing interest and effort to identify small molecule drugs that could potentially target disease-relevant dimers. In addition to providing an overview on how PCAs have allowed to gain better insights into GPCR-GPCR interactions, this review also aims at providing practical guidance on how to perform PCA-based assays
Investigation of fundamental and higher harmonic AC magnetic susceptibility of FeSe0.5Te0.5 superconductor
No full textWe present the complex harmonic magnetic susceptibilities chi(n) =chi'(n)-i chi `'(n) (n = 1, 3) of FeSe0.5Te0.5 polycrystalline superconducting sample. The ac magnetic susceptibility is measured as a function of various external perturbations such as temperature T, the ac magnetic field amplitude H-ac, frequency v, and the magnitude of dc bias field H-dc. The in-phase (chi'(n)) and out of phase (chi `'(n)) components of the fundamental and third harmonics of ac susceptibility are found to vary as a function of ac driven field. Particularly, the curves shift toward lower temperatures with increasing H-ac. Contrary to ac magnetic field (H-ac), no noticeable change has been observed within the range of applied dc magnetic field (H-dc) of up to 20 Oe. At a fixed ac magnetic field of H-ac = 0.5 Oe, both parts of the third harmonics show frequency dependence. The imaginary part of the third harmonics, chi `'(3) shows a small peak followed by a negative minimum at lower temperatures. The small peak diminishes as the frequency increases. The negative minimum suppresses and shifts towards the higher temperatures as we increase the frequency. To better understand the ac magnetic response under the influence of various perturbations, we have analyzed the polar plots (Cole-Cole) of the complex ac susceptibility for both the harmonics. Our analysis suggests that the studied sample is in a vortex glass state, characterized by a collective flux creep with in Bean's model, while the Kim-Anderson model is ruled out
Individual borrowing and default behaviour in surplus and constrained credit environments: evidence from India
No full textThe present article studies borrowing behaviour between credit surplus and credit constrained environments in the context of microfinance, with respect to rural borrowing. Surplus and constrained environments get defined based on the number of the state-promoted self help groups (SHGs) in the district, and the volume of credit disbursed through these SHGs. Four hundred nineteen respondents comprising of farmers, off-farm workers, farm labourers, small businesspersons, SHG members and chit-fund or cooperative members were interviewed in the surplus district of Chittoor and the constrained district of Nalgonda in the erstwhile state of Andhra Pradesh. Statistical analyses comprising of OLS, binary logistic regression, ANOVA, t-test and chi-square tests show that surplus environments offer more adverse credit terms, especially for farmers and farm labourers. Further, surplus causes over-borrowing and defaults. Constraint propels planned repayments. Both the environments offer varying credit terms across trades. We also observe better lending terms when farmers and traders are among lenders in a constraint environment. Interlinking factor markets like land, labour and capital in a constrained environment leads to efficient outcomes, reinforcing the theory of New Institutional Economics
Investigation of the elastically shock-compressed region and elastic-plastic shock transition in single-crystalline copper to understand the dislocation nucleation mechanism under shock compression
No full textShock-induced plasticity in FCC crystals has been demonstrated in many experimental and numerical simulation studies. Even though some theories have been proposed with regard to dislocation nucleation, the phenomenon occurring in the elastically shock-compressed region and the elastic-plastic transition region, which might be the origin region for dislocation nucleation, is largely unexplored. In this work, we present a molecular dynamics simulation of the shock compression of a Cu single crystal along the < 110 & rang; direction specifically focusing on the mechanisms observed in the elastically compressed and the elastic-plastic transition regions. A distribution of planes of high and low atomic volume is observed in the elastically compressed region near the shock front, but the distribution becomes random as the elastic-plastic transition regime is approached. Density variations are also observed. It is observed that the formation of the defects initiates through local atomic shuffling/rearrangement. Shear stress distribution shows values greater than those required for homogeneous nucleation, and Shockley partials are observed at a certain region behind the shock front. Potential energy variations are also observed in these regions, explaining the mechanisms leading to dislocation nucleation. The present findings shed new insight into the mechanism of dislocation nucleation in shock-induced single-crystal FCC metals
Molybdenum disulfide/reduced graphene oxide hybrids with enhanced electrocatalytic activity: An efficient counter electrode for dye-sensitized solar cells
No full textDevelopment of low cost, metal-free electrodes for photovoltaic applications is critical to meet future energy demands. In this work, the one-step hydrothermal synthesis and electrocatalytic activity of molybdenum disulfide/reduced graphene oxide (MoS2-rGO) hybrids are investigated as high-performance counter electrode materials for dye-sensitized solar cells (DSSCs). The crystal structure and morphology analyses of as-prepared MoS2-rGO hybrids indicated the presence of MoS2 nanostructures having a petal-like morphology on rGO sheets. Raman spectroscopy provided evidence for weak Van der Waals interactions between MoS2 and rGO layers along with a low defect density. DSSCs made with counter electrodes (CEs) of MoS2-rGO hybrids, showed an impressive power conversion efficiency of 7.83% surpassing the DSSCs with CEs of pristine MoS2 (5.97%) and the conventional Pt (7.57%). The cyclic voltammetry and electrochemical impedance studies have shown that the incorporation of reduced graphene oxide in the MoS2 nanostructures significantly decreased the charge transfer resistance and improved the electrocatalytic activity of their CEs. This is partly attributed to the morphology of the hybrid in which the petal-like MoS2 nanostructures on the rGO sheets provided numerous catalytic sites, which, in turn, enhanced the charge transfer across the CE providing a synergistically high performance. These results have indicated that the MoS2-rGO hybrids are promising alternatives to the conventional Pt-based CEs in DSSCs
Intramolecular hydrogen bond directed distribution of conformational populations in the derivatives of N `-benzylidenebenzohydrazide
No full textExtensive investigation by 1D and various 2D NMR techniques revealed the presence of only E isomers with respect to the C & xe001;N bond and the existence of cis/trans conformations in the synthesized N `-benzylidenebenzohydrazide and its derivatives. The stable conformations of these molecules are attributed to the rotation of the molecular fragment around the C(O)-N bond. Interestingly, the conformational rigidity and the populations of the conformers are governed by the strengths of the intramolecular hydrogen bonds (HBs) between the ortho substituent on the benzoyl ring and the proton of the amide group, thereby permitting the architectural design of the preferred conformation of the molecules. The temperature perturbation studies and dilution studies using solvents of different polarities aided in the interpretation of inter- and intra-molecular HB interactions. The engagement of organic fluorine in the intramolecular HB is indubitably ascertained by the detection of the interaction strengths of a significant magnitude between organic fluorine and the NH proton, where the only mode of magnetization transfer between the interacting nuclei is HB ((1h)J(FH)). This is further endorsed by a physical parameter dependent perceivable variation in the strength of (1h)J(FH). The weak molecular interactions are further ascertained by DFT based computations
Giant dielectric macroporous graphene oxide foams with aqueous salt solutions: Impedance spectroscopy
No full textUltralight and ultrathin dielectric materials with high dielectric permittivity and power densities are required to meet the ever-increasing demands of microelectronic and energy storage devices. In the present study, we demonstrate the feasibility of achieving giant dielectric performance of light weight, highly porous three-dimensional architectures of insulating graphene oxide (GO) foams by saturating the pores with liquid containing mobile ions. Dielectric behavior of GO foam is investigated over a range of frequencies (1 kHz-10 kHz) by employing electrochemical impedance spectroscopy. The relative permittivity of pristine GO foam is shown to improve by five orders upon saturating the pores with different concentrations of aqueous NaCl solutions. Dielectric constants of foams saturated with aqueous NaCl solutions are measured to be of the order of 10(6) at high frequencies (1 kHze10 kHz) and are observed to enhance to 10(8) at lower frequencies down to 0.01 Hz. Various contributions to the measured capacitance are deciphered by modelling the impedance data to an equivalent circuit in order to evaluate the exact contribution from dipole orientation. The plausible reasons for the enhanced dielectric behavior are emphasized. (C) 2019 Elsevier Ltd. All rights reserved