Constraining chameleon field driven warm inflation with Planck 2018 data

The European Physical Journal C - We study the Yukawa model with one scalar and one axial scalar fields, coupled to N copies of Dirac fermions, in curved spacetime background. The theory possesses...     

Immobilization of alkaliphilic Bacillus sp. cells for xylanase production using batch and continuous culture

Agar-immobilized alkaliphilic Bacillus sp. AR-009 cells were used for xylanase production using batch and continuous culture. In a batch culture, maximum enzyme production was observed after 48 h and remained high up to 72 h. In repeated batch cultivation, immobilized cells produced an appreciable level of xylanase activity in seven consecutive batches without any significant decline in productivity. For continuous xylanase production, immobilized cells were packed in a jacketed glass column and sterile medium was continuously pumped. A stable continuous production of xylanase was observed over a period of 1 mo. The volumetric productivity of the continuous culture was 17-fold higher than the batch culture using free cells.     

Polymer-modified glassy carbon electrode for the electrochemical detection of quinine in human urine and pharmaceutical formulations

Glassy carbon electrode was modified by electropolymerization of 4-amino-3-hydroxynaphthalene sulfonic acid. Cyclic voltammetric study of quinine showed higher current response at the modified electrode compared to the bare and activated glassy carbon electrodes in pH 7.0 phosphate buffer solution. Under optimized conditions, a calibration curve was obtained by square wave voltammetry at the modified electrode. The linear relationship between the peak current and the concentration of quinine in the range of 1.0?×?10^?7 to 1.0?×?10^?5 M was I _pa (in microamperes)?=?6.26C (in micromolars)?+?0.2997 (R ²?=?0.999). The detection limit calculated (S/N?=?3) was 1.42?×?10^?8 M, which is much lower than similar reports. The method was successfully applied for the determination of quinine in spiked human urine, and pharmaceutical formulations and recovery values >90 % were obtained.     

High-Performance Bismuth-Doped Nickel Aerogel Electrocatalyst for the Methanol Oxidation Reaction

Low-cost, non-noble-metal electrocatalysts are required for direct methanol fuel cells, but their development has been hindered by limited activity, high onset potential, low conductivity, and poor durability. A surface electronic structure tuning strategy is presented, which involves doping of a foreign oxophilic post-transition metal onto transition metal aerogels to achieve a non-noble-metal aerogel Ni₉₇Bi₃ with unprecedented electrocatalytic activity and durability in methanol oxidation. Trace amounts of Bi are atomically dispersed on the surface of the Ni₉₇Bi₃ aerogel, which leads to an optimum shift of the d-band center of Ni, large compressive strain of Bi, and greatly increased conductivity of the aerogel. The electrocatalyst is endowed with abundant active sites, efficient electron and mass transfer, resistance to CO poisoning, and outstanding performance in methanol oxidation. This work sheds light on the design of high-performance non-noble-metal electrocatalysts.     

Three-dimensional static and dynamic stiffness analyses of the cable driven parallel robot with non-negligible cable mass and elasticity

This study investigates the three-dimensional static and dynamic stiffness analyses of the cable driven parallel robot by considering cable mass, elasticity, and mass of end-effector. According to these models, optimization of cable tensions and cable lengths using fminimax solver is performed to determine the static stiffness. Static and dynamic stiffness of the cables are obtained with simulations. Results show that analyses in three-dimension are very important to measure the actual performance of the cable driven parallel robot. This demonstrates potential for general applicability and motion of the cable driven parallel robot.     

High‐Performance Bismuth‐Doped Nickel Aerogel Electrocatalyst for the Methanol Oxidation Reaction

Low‐cost, non‐noble‐metal electrocatalysts are required for direct methanol fuel cells, but their development has been hindered by limited activity, high onset potential, low conductivity, and poor durability. A surface electronic structure tuning strategy is presented, which involves doping of a foreign oxophilic post‐transition metal onto transition metal aerogels to achieve a non‐noble‐metal aerogel Ni₉₇Bi₃ with unprecedented electrocatalytic activity and durability in methanol oxidation. Trace amounts of Bi are atomically dispersed on the surface of the Ni₉₇Bi₃ aerogel, which leads to an optimum shift of the d‐band center of Ni, large compressive strain of Bi, and greatly increased conductivity of the aerogel. The electrocatalyst is endowed with abundant active sites, efficient electron and mass transfer, resistance to CO poisoning, and outstanding performance in methanol oxidation. This work sheds light on the design of high‐performance non‐noble‐metal electrocatalysts.     

Influence of particle size on the low and high strain rate behavior of dense colloidal dispersions of nanosilica

Shear thickening is a non-Newtonian flow behavior characterized by the increase in apparent viscosity with the increase in applied shear rate, particularly when the shear rate exceeds a critical value termed as the critical shear rate (CSR). Due to this remarkable property of shear-thickening fluids (STFs), they are extensively used in hip protection pads, protective gear for athletes, and more recently in body armor. The use of STFs in body armor has led to the development of the concept of liquid body armor. In this study, the effect of particle size is explored on the low and high strain rate behavior of nanosilica dispersions, so as to predict the efficacy of STF-aided personal protection systems (PPS), specifically for ballistic applications. The low strain rate study was conducted on cone and plate rheometer, whereas the high strain rate characterization of STF was conducted on in-house fabricated split Hopkinson pressure bar (SHPB) system. Spherical nanosilica particles of three different sizes (100, 300, and 500 nm) as well as fumed silica particles of four different specific surface areas (Aerosil A-90, A-130, A-150, and A-200), respectively, were used in this study. The test samples were prepared by dispersing nanosilica particles in polypropylene glycol (PPG) using ultrasonic homogenization method. The low strain rate studies aided in determining the CSR of the synthesized STF dispersions, whereas the high strain rate studies explored the impact-resisting ability of STFs in terms of the impact toughness and the peak stress attained during the impact loading of STF in SHPB testing.