Use of AgInTe2 for optoelectronic switching at higher frequencies

A possible application of AgInTe₂ for optoelectronic switching is reported. Alternating and direct current (a.c. and d.c.) response of the material has been studied over a wide frequency range (5 Hz to 1 MHz) through measurements of conductance, capacitance and photocurrent at different temperature and illumination levels. The switching/recovery time has been analysed in terms of time constant and found to be of the order of microseconds for this material. Higher frequencies of operation (>40 kHz) are preferable because, at such frequencies, becomes almost independent of illumination level and temperature. Furthermore, the switching speed can be conveniently controlled with d.c. bias applied across the sample. Elliott's CBH model has been satisfactorily used to explain the switching behaviour for AgInTe₂.     

Correlation of burst pressure of GRP cylinders with the stress wave factor

Glass fibre-reinforced plastic (GRP) cylinders are increasingly used for highly stressed structural elements. The higher the demands on the materials, the higher are the fault detection requirements to be met by non-destructive materials testing methods. Acousto-ultrasonics is a valuable aid for the non-destructive evaluation of GRP composite materials, because it may be the answer to evaluating effects of subtle defects in composites. The aim of the research is to evaluate the burst pressure of GRP cylinders by acousto-ultrasonics techniques. The theoretical results have been found to be in good agreement with the experimental values. Hence the results strongly suggest that stress wave factor measurements can be exploited successfully to predict burst pressure of GRP cylinders.Nomenclature P Internal pressure, kgf cm^–2 - d Internal diameter, cm - t Thickness of cylinder, cm - (N ,N ,N ) Resultant forces, kgf - (M ,M ,M ) Moments, kg cm - [A] Extensional stiffness matrix - [B] Bending stretching coupling matrix - [D] Flexural stiffness matrix - ( ⁰ , ⁰ , ⁰ ) Midplane strains - (k ,k ,k ) Curvatures - n Number of laminae - Z Distance from midplane, cm - _u Ultimate tensile strength of GRP composite, kg cm^–2 - S _W Stress wave factor - m Material parameter - Filament winding angle     

Effect of laser irradiation on the electrical properties of amorphous germanium films

Amorphous films of germanium were grown using a vacuum evaporation technique, on glass substrates kept at room temperature. As-grown films were irradiated with Q-Switched Nd-YAG laser pulses (=1.06 m, 20nsec, 10 to 50Jcm^–2). The d.c. conductivity measurements were made in the temperature range 77 to 300 K. It was observed that the effect of laser irradiation was similar to the effect caused by the thermal annealing of the films. The d.c. conductivity data were analysed in the light of Mott's theory of a variable range hopping conduction process.     

Barium ferrite: Preparation by liquid mix technique and its characterization

Barium ferrite has been prepared by a novel non-conventional preparation method known as the liquid mix technique which involves the preparation of citrates of the metals concerned. The decomposition of the citrates indicated a gradual transition from an amorphous material to a crystalline phase leading to the formation of barium ferrite at 600° C as indicated by the X-ray diffraction and Mössbauer measurements. Submicrometre-sized particles of the ferrite could be obtained directly on decomposition of the citrates, thus avoiding the milling or grinding operations normally employed to reduce the particles to the size required for obtaining good magnetic properties. The best properties (coercivity and remanence) were obtained for the ferrite sintered around 990° C.     

On the synthesis and characterization of a new manganite type CMR material: La0.7Hg0.3MnO3

A new manganite type CMR material, La_0.7Hg_0.3MnO₃ has been successfully synthesized and has been found to exhibit magnetoresistance (≈9%) at low fields (≈1.5 kG). The synthesis has been carried out through a solid state reaction route consisting of the formation of La_0.7MnO₃ followed by diffusion of Hg leading to La_0.7Hg_0.3MnO₃. The as grown samples are polycrystalline and correspond to an orthorhombic unit cell with the lattice parameters; a=5.5183 Å, b=5.6383 Å and c=7.5368 Å. The typical grain size as revealed by scanning electron microscopy is in the range of 0.5–2 μm. The ρ–T behaviour shows a peak at T_IM=227 K. The ρ–T behaviour above this temperature corresponds to that of an insulator and below this to that of a metal. The ρ–T behaviour remains unaltered when a magnetic field (H_dc=1.5 kG) is applied. However, with this magnetic field a drop in the resistivity is observed up to 77 K. At room temperature the magnetoresistance ratio (MRR) is too small but it steadily increases as the temperature is decreased. Thus, MRRs at 227.13 and 77 K are 3.41 and 9.05%, respectively, in an applied field of H_dc=1.5 kG. At a given temperature the variation in MRR with field H_dc is rapid at lower field values (H_dc<1.2 kG) and scales linearly for higher field values (H_dc>1.2 kG). It may be mentioned that the present work on the synthesis and magnetoresistance behaviour of La_0.7Hg_0.3MnO₃, is the first of its type.     

All Ag Nanoparticles Are Not the Same: Covalent Interactions between Ag Nanoparticles and Nitrile Groups Help Combat Drug- and Ag-Resistant Bacteria

Antimicrobial resistance has long been viewed as a lethal threat to global health. Despite the availability of a wide range of antibacterial medicines all around the world, organisms have evolved a resistance mechanism to these therapies. As a result, a scenario has emerged requiring the development of effective antibacterial drugs/agents. In this article, we exclusively highlight a significant finding reported by Zbořil and associates (Adv. Sci. 2021, 2003090). The authors construct a covalently bounded silver-cyanographene (GCN/Ag) with the antibacterial activity of 30 fold higher than that of free Ag ions or typical Ag nanoparticles (AgNPs). Ascribed to the strong covalent bond between nitrile and Ag, an immense cytocompatibility is shown by the GCN/Ag towards healthy human cells with a minute leaching of Ag ions. Firm interactions between the microbial membrane and the GCN/Ag are confirmed by molecular dynamics simulations, which rule out the dependence of antibacterial activity upon the Ag ions alone. Thus, this study furnishes ample scope to unfold next-generation hybrid antimicrobial drugs to confront infections arising from drug and Ag-resistant bacterial strains.     

AKT Inhibitors: The Road Ahead to Computational Modeling-Guided Discovery

AKT, is a serine/threonine protein kinase comprising three isoforms—namely: AKT1, AKT2 and AKT3, whose inhibitors have been recognized as promising therapeutic targets for various human disorders, especially cancer. In this work, we report a systematic evaluation of multi-target Quantitative Structure-Activity Relationship (mt-QSAR) models to probe AKT’ inhibitory activity, based on different feature selection algorithms and machine learning tools. The best predictive linear and non-linear mt-QSAR models were found by the genetic algorithm-based linear discriminant analysis (GA-LDA) and gradient boosting (Xgboost) techniques, respectively, using a dataset containing 5523 inhibitors of the AKT isoforms assayed under various experimental conditions. The linear model highlighted the key structural attributes responsible for higher inhibitory activity whereas the non-linear model displayed an overall accuracy higher than 90%. Both these predictive models, generated through internal and external validation methods, were then used for screening the Asinex kinase inhibitor library to identify the most potential virtual hits as pan-AKT inhibitors. The virtual hits identified were then filtered by stepwise analyses based on reverse pharmacophore-mapping based prediction. Finally, results of molecular dynamics simulations were used to estimate the theoretical binding affinity of the selected virtual hits towards the three isoforms of enzyme AKT. Our computational findings thus provide important guidelines to facilitate the discovery of novel AKT inhibitors.     

Application of Machine Learning Algorithms With and Without Principal Component Analysis for the Design of New Multiphase High Entropy Alloys

Metallurgical and Materials Transactions A - The design of high entropy alloys (HEAs) can be accelerated using machine learning (ML) algorithms. In the current study, the design parameter’s...     

Effects of temperature and blank holding force on biaxial forming behavior of aluminum sheet alloys

Biaxial forming behavior is investigated for three aluminum sheet alloys (Al 5182 containing 1% Mn (5182+Mn), Al 5754, and 6111-T4) using a heated die and punch in the warm forming temperature range of 200–350 °C. It is found that, while all three alloys exhibit significant improvement in their formability compared with that at room temperature, the non-heat-treatable alloys 5182 + Mn and 5754 give higher part depths than that of heat-treatable 6111-T4. The formability generally increases with decreasing BHP (BHP), but increasing the forming temperature and/or BHP minimizes the wrinkling tendency and improves the forming performance. The stretchability of the sheet alloys increase with increasing temperature and increasing BHP. For the alloys and forming conditions involved in the current study, the formability, measured in terms of part depth, comes mainly from the drawing of metal into the die cavity, although stretching effects do influence the overall forming behavior. The optimum formability is achieved by setting the die temperature 50 °C higher than the punch temperature to enhance the drawing component. Setting the die temperature higher than the punch temperature also improves the strain distribution in a part in such a manner that postpones necking and fracture by altering the location of greatest thinning.     

Ionic liquid mediated nano-composite polymer gel electrolyte for rechargeable battery application

ABSTRACT

Nano-composite polymer gel electrolytes (NPGEs) based on polymer poly(vinylidene fluoride-co-hexafluoropropylene) PVdF-HFP, ionic liquid, 1-butyl-3- methylimidazolium bis(trifluoromethanesulfonyl)imide BMIMTFSI, Li-salt along with the addition of SiO₂ nanoparticles have been synthesized and characterized by various techniques. Prepared NPGEs show high room temperature ionic conductivity (~10^?3 S/cm) and have a wide electrochemical window (ECW) (~3.3–3.5 V). The galvanostatic charge/discharge profile was studied by sandwiching best performing NPGEs between a LiFePO₄ cathode and lithium metal anode. The specific discharge capacity of the cell (Li/NPGE/LiFePO₄) room temperature at 0.1C rate is found to be 138 mAh/g.