Development and Characterization of Inorganic-Organic (Si-O-Al) Hybrid Geopolymeric Precursors via Solid State Method

Silicon - In this study, an innovative one part, solution free concept applied for the development of hybrid inorganic–organic geopolymeric precursors having Si-O-Al networks at the precursor...     

Perspectives on Inhibiting β‐Amyloid Aggregation through Structure‐Based Drug Design

Targeting β‐amyloid (Aβ) remains the most desired strategy in Alzheimer’s disease (AD) drug discovery research. Many peptides that specifically target Aβ aggregates are known, encompassing efforts from both industrial and academic research settings. However, in clinical terms, not much success has been gained with peptide research; in turn, small drug‐like molecules are already globally recognized as showing promise as an alternate approach. Aβ aggregation inhibitors are the most important part of the multifunctional drug design regimen for treating AD. Unfortunately, rational drug design approaches with small molecules are still in the initial stages. Herein we highlight, update, and elaborate on the structural anatomy of Aβ and known Aβ aggregation inhibitors in hopes of helping to optimize their use in structure‐based drug design approaches toward inhibitors with greater specificity. Furthermore, we present the first review of efforts to target a previously uncharacterized region of acetylcholinesterase: the N‐terminal 7–20 sub‐region, which was experimentally elucidated to participate in Aβ aggregation and deposition.     

Effect of A‐ or B‐site doping of perovskite calcium manganite on structure,resistivity, and thermoelectric properties

Bismuth‐, lanthanum‐, and molybdenum‐doped calcium manganite (CaMnO₃, abbreviated Mn113) are synthesized by solid‐state synthesis route from their respective oxide precursors at a same doping level (x=0.05). Depending on the ionic sizes, trivalent dopants (Bi³⁺ and La³⁺) replace Ca²⁺(A site), while penta/hexavalent dopant Mo⁵⁺/Mo⁶⁺ replaces Mn⁴⁺ (B site) in the Mn113 structure. XRD of all three doped samples confirm formation of single phase. In all three samples, doping causes unit cell volume to expand, while volume expansion is maximum for the Mo‐Mn113. The transport behavior of the doped samples follows small polaron hopping mechanism. Resistivity of the doped samples depends not only on the carrier concentration but also on the effective bandwidth determined by the structural distortion introduced by the dopant ions. Bi‐Mn113 has highest resistivity at the both temperature end, while La‐Mn113 has the lowest. Thermopower is determined by the carrier concentration only and does not depend on dopant type, having value ~260 μV/K at 1000 K. At high (>800 K), S reaches a saturation value and becomes independent of T. La‐Mn113 is having highest figure of merit (zT) 0.19 at 1000 K.     

An ocular wavefront sensor based on binary phase element: design and analysis

A modal wavefront sensor for ocular aberrations exhibits two main advantages compared to a conventional Shack–Hartmann sensor. As the wavefront is detected in the Fourier plane, the method is robust against local loss of information (e.g. local opacity of ocular lens as in the case of cataract), and is not dependent on the spatial distribution of wavefront sampling. We have proposed a novel method of wavefront sensing for ocular aberrations that directly detects the strengths of Zernike aberrations. A multiplexed Fourier computer-generated hologram has been designed as the binary phase element (BPE) for the detection of second-order and higher-order ocular aberrations (HOAs). The BPE design has been validated by comparing the simulated far-field pattern with the experimental results obtained by displaying it on a spatial light modulator. Simulation results have demonstrated the simultaneous wavefront detection with an accuracy better that ～λ/30 for a measurement range of ±2.1λ with reduced cross-talk. Sensor performance is validated by performing a numerical experiment using the City data set for test waves containing second-order and HOAs and measurement errors of 0.065?µm peak-to-valley (PV) and 0.08?µm (PV) have been obtained, respectively.     

Dielectric relaxation in complex perovskite Ba(Bi1/2Ta1/2)O3

A new lead-free perovskite Ba(Bi_1/2Ta_1/2)O₃ was prepared by conventional ceramic fabrication technique at 1,200 °C/4 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were determined from the experimental results using FullProf software. The crystallite size and lattice strain were estimated from Williamson-Hall approach. XRD analysis of the compound indicated the formation of a single-phase cubic structure with the space group Pm3m. EDAX and SEM studies were carried out in order to evaluate the quality and purity of the compound. Permittivity data showed a low temperature coefficient of capacitance (T _CC  < 4%) up to +125 °C. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. Electric modulus studies supported the hopping type of conduction in Ba(Bi_1/2Ta_1/2)O₃.     

Characterisation and oxidation of LVOF sprayed Al2O3–40%TiO2 coating on superni 601 and superni 718 superalloys at 800 and 900°C

Failure of components due to high temperature oxidation is the major degradation mechanism in boiler and gas turbine industries. Superalloys having superior mechanical properties and creep resistance are used in these applications but lack resistance to oxidation under aggressive environments. Protective coatings are used to improve their oxidation resistance in such applications. In the present investigation, Al₂O₃–40%TiO₂ coating was deposited on superni 718 and superni 601 superalloys by low velocity oxy fuel process. The as sprayed coating was characterised for microhardness, surface roughness, scanning electron microscopy and X-ray diffraction analysis. High temperature oxidation behaviour of Al₂O₃–40%TiO₂ coated and uncoated superni 718 and superni 601 superalloys has been evaluated at the elevated temperatures of 800 and 900°C for total duration of 50 cycles under cyclic conditions. Each cycle consisted of keeping the samples for 1 h at the elevated temperature followed by 20 min cooling in ambient air. Al₂O₃–40TiO₂ coating in the as sprayed condition showed the presence of Al₂O₃–TiO₂, α-Al₂O₃, TiO₂ as the main phases. Al₂O₃–40%TiO₂ coating on superni 718 and superni 601 superalloys has shown a lower oxidation rate as compared to those of uncoated superalloys. However, the oxidation rate of the coating was not steady due to the occurrence of spallation/sputtering at various stages. The coating was found adherent on the substrate superalloys throughout the study.     

Determination of satellite nadir and azimuth angles for a tilting sensor

The procedure for the determination of satellite nadir and azimuth angles has beenverifiedusing the Coastal Zone Color Scanner (CZCS) geolocation algorithm formulated by Wilson and co-workers in 1981. The error involved in the determination of satellite nadir and azimuth angles for positive and negative tilt of the mirror using the above method is discussed. A simple method to determine nadir and azimuth angles for a tilting mirror is proposed. The nadir and azimuth angles after roll, pitch and yaw of the satellite are presented.     

Structure of lean premixed hydrogen-air flames in an annular microcombustor

Self-sustainable combustion and narrow stability limits are the most critical issues in microcombustors (length scale 1 mm) as increased heat losses can lead to thermal quenching of the flame. Hydrogen is a potential fuel for microcombustion due to its high specific energy and wide flammability limits. This work focuses on the lean premixed hydrogen-air flames stabilized in a newly developed annular microcombustor. Detailed axisymmetric numerical calculations involving multistep kinetics, multicomponent mass-heat transport, conjugate heat transfer, and thermal radiation in gas and solid media are performed. It has been shown that flame stabilization occurs by preheating even though wall temperatures are higher than the autoignition temperature. Results unravel the importance of H radical reactions in the kinetics of microflames in low- and high-temperature regions of the microcombustor.     

Preparation of rice analogues using extrusion technology

Rice is considered as staple food in many parts of the world. An issue of concern is the breakage of rice kernels in milling processes, and these broken kernels are not generally accepted by consumers. These broken kernels can be mixed with some desired additives to improve their quality and extruded for the preparation of reconstituted rice kernels or rice analogues. Various studies have been conducted for the preparation of the rice analogues in the past few decades, and recently attempts have been made to fortify these analogues with protein, certain vitamins and minerals. The main features such as colour, shape, size, texture, and cooking characteristics and cooking time of these rice‐like grains can be tailored to the requirements of specific applications by modification of the extrusion parameters. Various organisations, such as Wuxi NutriRice Co. (DSM/Buhler) and China National Cereals, Oils and Foodstuffs Corporate (COFCO), Superlative Snacks Inc., Vigui and PATH, have utilised this technique to prepare fortified and reconstituted rice. Studies have shown that it is possible to improve the nutritional quality of rice by fortified rice analogues. This article reviews research results of the many approaches to the formation of fortified rice analogues by extrusion‐based technologies.