Coupled surface-enhanced Raman spectroscopy and electrical conductivity measurements of 1,4-phenylene diisocyanide in molecular electronic junctions

Probing the structure of molecules in a metal-molecule-metal junction under an applied voltage is critical for understanding molecular electron transport properties. We present an approach that allows recording surface-enhanced Raman spectra simultaneously with electrical measurements of a monolayer of molecules in molecular electronic junctions. 1,4-Phenylene diisocyanide in two different types of junctions was used to illustrate the approach. The results show that the molecular integrity was intact in the molecular junctions and under the applied bias. The monolayer sensitivity of the approach provides a new powerful tool for characterizing molecular structure in a molecular electronic junction.     

Normalized Antecedent Precipitation Index Based Model for Prediction of Runoff from Un-Gauged Catchments

Water Resources Management - The ‘Normalized Antecedent Precipitation Index (NAPI)’ model developed based on water balance equation was found capable to predict runoff yields from...     

Comparing double-step and penalty-based semirecursive formulations for hydraulically actuated multibody systems in a monolithic approach

The simulation of mechanical systems often requires modeling of systems of other physical nature, such as hydraulics. In such systems, the numerical stiffness introduced by the hydraulics can become a significant aspect to consider in the modeling, as it can negatively effect to the computational efficiency. The hydraulic system can be described by using the lumped fluid theory. In this approach, a pressure can be integrated from a differential equation in which effective bulk modulus is divided by a volume size. This representation can lead to numerical stiffness as a consequence of which time integration of a hydraulically driven system becomes cumbersome. In this regard, the used multibody formulation plays an important role, as there are many different procedures for the constraint enforcement and different sets of coordinates to choose from. This paper introduces the double-step semirecursive approach and compares it with a penalty-based semirecursive approach in case of coupled multibody and hydraulic dynamics within the monolithic framework. To this end, hydraulically actuated four-bar and quick-return mechanisms are analyzed as case studies. The two approaches are compared in terms of the work cycle, energy balance, constraint violation, and numerical efficiency of the mechanisms. It is concluded that the penalty-based semirecursive approach has a number of advantages compared with the double-step semirecursive approach, which is in accordance with the literature.

     

Single-channel speech enhancement using implicit Wiener filter for high-quality speech communication

International Journal of Speech Technology - Speech enables easy human-to-human communication as well as human-to-machine interaction. However, the quality of speech degrades due to background...     

Detection of Copy-Move Forgery in Digital Image Using Multi-scale,Multi-stage Deep Learning Model

Neural Processing Letters - Images are an important source of information and copy-move forgery (CMF) is one of the vicious forgery attacks. Its objective is to conceal sensitive information from...     

Temporal stability of oxygen-ion conductivity in 1Nb2O5-10Sc2O3-89ZrO2

A slight Nb₂O₅ co-doping in 11Sc₂O₃-89ZrO₂ was earlier reported to stabilize the high-symmetry cubic phase completely and enhances the conductivity significantly. The present work looked at the temporal stability of conductivity in 1Nb₂O₅-10Sc₂O₃-89ZrO₂ (1Nb10ScSZ) for the electrolyte application in solid oxide fuel cells. In-situ conductivity measurement was done using impedance spectroscopy at 650 °C in the air for 2000 h. A substantial conductivity loss (29%) was observed in the first 1000 h. Following which, conductivity remained relatively stable for the next 1000 h. Impedance analysis showed that the main contribution to the conductivity degradation was from grain conductivity. Phase analysis performed using XRD, TEM and Raman spectroscopy revealed that both the unaged and aged 1Nb10ScSZ samples consisted of metastable t″-phase. However, the extent of tetragonality was found to increase after ageing. The formation of low-symmetry phase was suggested to be the reason for the grain conductivity loss in 1Nb10ScSZ.     

Visible quantum cutting in Tb<Superscript>3+</Superscript> doped BaGdF<Subscript>5</Subscript> phosphor for plasma display panel

Visible quantum cutting (QC) via down-conversion and enhancement in photoluminescence properties has been observed in terbium (Tb³⁺) doped BaGdF₅ phosphor. This phosphor was synthesized by varying molar concentration of Tb³⁺ ions via co-precipitation method. The prepared phosphor was characterized through X-ray diffraction technique. The photoluminescence spectra of BaGdF₅:Tb³⁺ phosphor measured under vacuum ultraviolet or UV excitation. The QC process was observed in prepared phosphor due to cross relaxation and direct energy transfer between Tb³⁺ and Tb³⁺ or Tb³⁺ and Gd³⁺ ions depending on the excitation wavelength. The maximum quantum efficiencies were found to be 162, 174 and 177 %, under the excitation of 172, 187 and 240 nm respectively. The green emission of 544 nm was observed at excitation of 172 and 187 nm. Hence this phosphor may be prime candidate for application in plasma display panels and mercury free fluorescent lamps.     

Enhanced Fear Memories and Altered Brain Glucose Metabolism (18F-FDG-PET) following Subanesthetic Intravenous Ketamine Infusion in Female Sprague–Dawley Rats

Although women and men are equally likely to receive ketamine following traumatic injury, little is known regarding sex-related differences in the impact of ketamine on traumatic memory. We previously reported that subanesthetic doses of an intravenous (IV) ketamine infusion following fear conditioning impaired fear extinction and altered regional brain glucose metabolism (BGluM) in male rats. Here, we investigated the effects of IV ketamine infusion on fear memory, stress hormone levels, and BGluM in female rats. Adult female Sprague–Dawley rats received a single IV ketamine infusion (0, 2, 10, or 20 mg/kg, over a 2-h period) following auditory fear conditioning (three pairings of tone and footshock). Levels of plasma stress hormones, corticosterone (CORT) and progesterone, were measured after the ketamine infusion. Two days after ketamine infusion, fear memory retrieval, extinction, and renewal were tested over a three-day period. The effects of IV ketamine infusion on BGluM were determined using ¹⁸F-fluoro-deoxyglucose positron emission tomography (¹⁸F-FDG-PET) and computed tomography (CT). The 2 and 10 mg/kg ketamine infusions reduced locomotor activity, while 20 mg/kg infusion produced reduction (first hour) followed by stimulation (second hour) of activity. The 10 and 20 mg/kg ketamine infusions significantly elevated plasma CORT and progesterone levels. All three doses enhanced fear memory retrieval, impaired fear extinction, and enhanced cued fear renewal in female rats. Ketamine infusion produced dose-dependent effects on BGluM in fear- and stress-sensitive brain regions of female rats. The current findings indicate that subanesthetic doses of IV ketamine produce robust effects on the hypothalamic–pituitary–adrenal (HPA) axis and brain energy utilization that may contribute to enhanced fear memory observed in female rats.     

Study of Electromagnetic Properties of Fabricated NiFe2O4/Polyurethane Nanocomposites

Nickel ferrite loaded (NiFe₂O₄) segmented polyurethane (SPU) nanocomposites prepared by melt mixing method using microcompounder at temperature 185 °C in recirculation mode to ensure proper dispersion and distribution of nanoparticles at optimized residency time of 5 min. Three different weight percentages of nanocomposites (3, 5, and 10 wt %) was prepared and studied the electromagnetic property of nanocomposites obtained from complex permittivity and permeability. The effect of nanofiller (NiFe₂O₄) has been studied to assess their thermal properties using thermogravimetric analysis, differential scanning calorimetry, and thermomechanical analysis. The nanocomposites (NiFe₂O₄/SPU) have further been studied using FE-SEM, and the micrographs show embedded NiFe₂O₄ filler uniformly dispersed in SPU matrix without agglomeration (size 20–40 nm). It is also evident that further loading of nanofiller resulted in saturation effect yielding no applicable change in thermal behavior and revealed lesser melting enthalpy due to the coalescence of the nanofillers. X-ray diffraction and vibrating sample magnetometer also support the formation of the nanocomposite. The electric and magnetic properties of NiFe₂O₄ incorporated nanocomposite (NiFe₂O₄/SPU) may have potential application in microwave absorption. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48645.     

Activity of modified SnO2 catalysts for acid-catalysed reactions

The effect of Lewis and Brønsted acid modification on the catalytic behaviour of SnO₂ was studied. Modified AlCl₃, FeCl₃, ZnCl₂ and H₂SO₄ were used for this purpose. Catalytic activity was tested for Friedel–Crafts alkylation, acylation and Pechmann condensation. It was observed that the alkylation activity of SnO₂ was improved upon treatment with Lewis acids and Brønsted acids. However the acylation activity was observed only when SnO₂ was treated with H₂SO₄. Moderate improvement in the activity for Pechmann condensation reaction was observed in the case of all the modified catalysts. It was inferred that this method of modification resulted in an increase in acid strength as well as acidity of the parent oxide catalyst. © 1998 SCI