The location of atomic hydrogen in NiTi alloy: A first principles study

A first principles density functional theory study to investigate the H defect in NiTi alloy is presented. We have determined the interstitial H atom position in bulk B2 phase NiTi alloy. H positions on both the Ti and Ni terminated NiTi surfaces are calculated. Surface adsorptions of H atom on Ni/Ti terminated surfaces are calculated for a low surface coverage of 1.96 × 10¹⁴ cm^?2. We have also calculated the penetration barrier energy for an H atom from the surface site to the bulk lattice site.     

Adsorption and penetration of hydrogen in W: A first principles study

In BCC crystals, such as Tungsten (W), slippage has been observed on the (1 1 0) and (1 1 2) planes. In this work, hydrogen diffusion paths from three different W surfaces ((1 0 0), (1 1 0) and (1 1 2)) have been calculated using first principles density functional theory. Equilibrium sites for H at the surfaces are identified. The energetics for H penetration from the surfaces to the solute site in the bulk is calculated. It is found that for our low surface coverage of H (3.4 × 10¹⁴ H/cm²), approximately 2 eV is required for an H atom to penetrate any of the W surfaces considered in this study.     

Enhanced Fresnel zone plate coded microscopy of large-size objects

A scheme for microscopy of relatively large-size objects by using Fresnel zone plate (FZP) coded imaging (FZ-PCI) is digitally demonstrated. The limit on the source size in zone-plate-based microscopy comes from interference of out-of-focus multidiffraction orders of the FZP with the focused-order image. From the study of the angular spectrum of the coded image, it is shown that noise contribution from higher orders to a lower-order image can be digitally suppressed by selective propagation of spatial frequencies. Similarly, noise from aliasing and noise from lower orders to a higher-order image can be reduced by spatially limiting the coded image. To my knowledge for the first time, the results of digitally performed FZPCI-based microscopy of an object that is three times larger than the first zone of the FZP with a resolution better than 2 microm are presented and discussed.     

A macro level analysis of the airlift deployment problem

This paper presents mathematical models for a macro level analysis of the airlift deployment problem which involves the allocation of a limited number of aircraft towards the shipment of cargo and personnel between many origins and destinations within prescribed time windows. The problem has been modeled by three linear programming formulations in a manner such that it can be solved in a personal computer environment in a timely manner. The first and second formulations represent an explicit statement of the problem. These formulations attempt to optimally allocate strategic airlift resources towards the shipment of demand (cargo and personnel) such that the maximum amount of demand is delivered on time using preferred aircraft types. A much smaller statement of the problem is achieved in the third formulation by assuming that lateness is distributed evenly over all routes. Thus, the formulations offer a tradeoff between the degree of control to be exercised by the planner and the speed of computation. The paper presents the basic structure of these formulations along with some test results.     

Intergranular Corrosion Behavior of Low-Nickel and 304 Austenitic Stainless Steels

Intergranular corrosion (IGC) susceptibility for Cr-Mn austenitic stainless steel and 304 austenitic stainless steel (ASS) was estimated using electrochemical techniques. Optical and SEM microscopy studies were carried out to investigate the nature of IGC at 700 °C with increasing time (15, 30, 60, 180, 360, 720, 1440 min) according to ASTM standard 262 A. Quantitative analysis was performed to estimate the degree of sensitization (DOS) using double loop electrochemical potentiokinetic reactivation (DLEPR) and EIS technique. DLEPR results indicated that with the increase in thermal aging duration, DOS becomes more severe for both types of stainless steel. The DOS for Cr-Mn ASS was found to be higher (65.12% for 1440 min) than that of the AISI 304 ASS (23% for 1440 min). The higher degree of sensitization resulted in lowering of electrical charge capacitance resistance. Chronoamperometry studies were carried out at a passive potential of 0.4 V versus SCE and was observed to have a higher anodic dissolution of the passive film of Cr-Mn ASS. EDS studies show the formation of chromium carbide precipitates in the vicinity of the grain boundary. The higher Mn content was also observed for Cr-Mn ASS at the grain boundary.     

Overview on the Current Status of Hydrogen Energy Research and Development in India

The energy demand for the automobile and industrial sectors is increasing drastically worldwide. Conventional sources will no longer fulfil the growing energy demand and environmental pollution is a big concern. Thus, an alternative fuel for vehicles is highly required. The focus is shifted on renewable energy sources like hydrogen, which is abundant in nature. This review examines the continuous progress of hydrogen regarding production and storage techniques in India. Current studies and ongoing projects are summarized projecting the status of production, storage, and application of hydrogen. Challenges like infrastructure development, distribution, policies, cost, and public acceptance as obstacles for the commercialization of hydrogen-powered vehicles in the Indian market are analyzed.     

Dexamethasone eluting biodegradable polymeric matrix coated stent for intravascular drug delivery

Targeted drug delivery systems are used to minimize the adverse effects of the pharmaceutical agents while maintaining the high local drug concentrations. To minimize post-angioplasty complications like tissue hyperplasia and related restenotic events, cardiovascular stents coated with anti-inflammatory, anti-proliferative agents have been proposed. The efficacy and toxicity of local therapeutics depends upon drug release kinetics which will further decide drug deposition, distribution, and retention at the target site. Drug eluting stents (DES) presently possesses clinical importance as an alternative to coronary artery bypass grafting due to ease of procedure and comparable safety and efficacy. This paper focuses on preparation and evaluation of controlled drug release biodegradable systems for stent base drug delivery providing insight of the drug elution mechanism which ultimately governs release kinetics. Multiple layers of dexamethasone-biodegradable polymers were successfully spray coated on Co–Cr alloy L605 metallic stents by modified air brush technique. In vitro drug elution data acquired by high performance liquid chromatography (HPLC) revealed that release of dexamethasone can be modulated up to 3 weeks by optimized use of blends of biodegradable poly-l-lactide-co-caprolactone and polyvinyl pyrrolidone. Surface investigation by scanning electron microscopy (SEM) represented smooth surface finish without any irregularities suggesting the efficacy of utilization of optimal coating parameters for multiple layer coating.     

Raw Milk-Induced Protection against Food Allergic Symptoms in Mice Is Accompanied by Shifts in Microbial Community Structure

The mechanism underlying the allergy-protective effects of raw cow’s milk is still unknown, but the modulation of the gut microbiome may play a role. The effects of consuming raw cow’s milk or processed milk on fecal microbial communities were therefore characterized in an experimental murine model. C3H/HeOuJ mice were treated with raw milk, pasteurized milk, skimmed raw milk, pasteurized milk supplemented with alkaline phosphatase (ALP), or phosphate-buffered saline (PBS) for eight days prior to sensitization and challenge with ovalbumin (OVA). Fecal samples were collected after milk exposure and after OVA sensitization, and microbiomes were characterized using 16S ribosomal RNA gene amplicon sequencing. Treatment with raw milk prior to OVA sensitization increased the relative abundance of putative butyrate-producing bacteria from the taxa Lachnospiraceae UCG-001, Lachnospiraceae UCG-008, and Ruminiclostridium 5 (Clostridial clusters XIVa and IV), while it decreased the relative abundance of Proteobacterial genera such as Parasutterella, a putative pro-inflammatory bacterial genus. This effect was observed after eight days of raw milk exposure and became more pronounced five weeks later, after allergic sensitization in the absence of milk. Similar trends were observed after treatment with skimmed raw milk. Conversely, the feeding of pasteurized milk led to a loss of allergy protection and a putative dysbiotic microbiome. The addition of ALP to pasteurized milk restored the protective effect observed with raw milk and mitigated some of the microbial community alterations associated with milk pasteurization. Raw milk-induced protection against food allergic symptoms in mice is accompanied by an increased relative abundance of putative butyrate-producing Clostridiales and a decreased relative abundance of putative pro-inflammatory Proteobacteria. Given the safety concerns regarding raw milk consumption, this knowledge is key for the development of new, microbiologically safe, preventive strategies to reduce the incidence of allergic diseases.     

Triple-Networked Hybrid Hydrogels Reinforced with Montmorillonite Clay and Graphene Nanoplatelets for Soft and Hard Tissue Regeneration

Hydrogel is a three-dimensional (3D) soft and highly hydrophilic, polymeric network that can swell in water and imbibe a high amount of water or biological fluids. Hydrogels have been used widely in various biomedical applications. Hydrogel may provide a fluidic tissue-like 3D microenvironment by maintaining the original network for tissue engineering. However, their low mechanical performances limit their broad applicability in various functional tissues. This property causes substantial challenges in designing and preparing strong hydrogel networks. Therefore, we report the triple-networked hybrid hydrogel network with enhanced mechanical properties by incorporating dual-crosslinking and nanofillers (e.g., montmorillonite (MMT), graphene nanoplatelets (GNPs)). In this study, we prepared hybrid hydrogels composed of polyacrylamide, poly (vinyl alcohol), sodium alginate, MMT, and MMT/GNPs through dynamic crosslinking. The freeze-dried hybrid hydrogels showed good 3D porous architecture. The results exhibited a magnificent porous structure, interconnected pore-network surface morphology, enhanced mechanical properties, and cellular activity of hybrid hydrogels.