β-glucosidase assisted biosynthesis of gold nanoparticles: A green chemistry approach

Biogenic gold nanoparticles using medically important phytochemical (β-glucosidase) are demonstrated herein. The reduction capabilities of phytochemical and their ability to stabilize the new genre gold nanoparticles, were characterized using UV-visible, FT-IR, HR-TEM and XRD measurements. This report also focuses the newly formed gold nanoparticles application on promoting the defensive mechanism of silkworm Bombyx mori. The results highlight the possibility of green pathways to produce functionalized gold nanoparticles of medicinal significance.     

Low‐profile substrate integrated waveguide (SIW) cavity‐backed self‐triplexed slot antenna

A low‐profile self‐triplexed slot antenna is proposed for multiple system integrations. The antenna comprises of hybrid substrate integrated waveguide (SIW) cavity (a combination of a half‐mode circular and half‐mode rectangular SIW), radiating slot, and feeding network. A slot is imprinted on the upper metal‐layer of the SIW which splits the cavity into three radiating sections. It offers tri‐frequency bands when each section is excited separately. By finely tuning the antenna dimensions, it produces three frequency‐bands around 5.57, 7.17, and 7.65 GHz simultaneously utilizes a single slot with maintaining the intrinsic input‐port isolation better than 20 dB. This property helps to introduce the self‐triplexing phenomenon. Compared with the conventional multiband antennas that use an extra circuitry to ensure the port isolations, this design preserves compactness and easy to integrate with planar circuits Moreover, the proposed antenna is fabricated and the measured results mutually agreed with the simulated counterparts. The proposed design can be a feasible option for mobile transceiver applications.     

Poisson’s ratio of eTPU molded bead foams in compression via in situ synchrotron X-ray microtomography

In situ synchrotron X-ray microtomography was used to characterize the bulk deformation behavior by computing the Poisson’s ratio of expanded thermoplastic polyurethane (eTPU) molded bead foams used in footwear midsole during compression. Quantitative data on morphological characteristics were obtained using an iterative image processing workflow. Image correlation on the 4D datasets using DVC was performed to calculate the volumetric and axial strain to estimate the Poisson ratio. Strain maps from DVC showed the influence of variability in ligament thickness distribution on the global mechanical behavior exhibited which dominated the response seen in these bead foams. Finally, our results showed a strong correlation between Poisson ratio and distribution of ligament thickness in foams.

     

Application of Fracture Mechanics to Specify the Proof Load Factor for Clamp Band Systems of Launch Vehicles

This article presents a methodology for evaluation of the proof load factor (PLF) for clamp band system (CBS) made of M250 Maraging steel following fracture mechanics principles.CBS is most widely used as a structural element and as a separation system. Using Taguchi’s design of experiments and the response surface method (RSM) the compact tension specimens were tested to establish an empirical relation for the failure load (P _max) in terms of the ultimate strength, width, thickness, and initial crack length. The test results of P _max closely matched with the developed RSM empirical relation. Crack growth rates of the maraging steel in different environments were examined. Fracture strength (σ_f) of center surface cracks and through-crack tension specimens are evaluated utilizing the fracture toughness (K _IC). Stress induced in merman band at flight loading conditions is evaluated to estimate the higher load factor and PLF. Statistical safety factor and reliability assessments were made for the specified flaw sizes useful in the development of fracture control plan for CBS of launch vehicles.     

Sol–gel mediated surface modification of nanocrystalline NiFe2O4 spinel powders with amorphous SiO2

Surface modification of nanocrystalline NiFe₂O₄ spinel particles with amorphous SiO₂ by the sol–gel process at 350 °C was demonstrated. Amorphous phase of the SiO₂ layer was evaluated by X-ray diffraction technique. Structural coordination of the pristine and SiO₂ coated NiFe₂O₄ particles as investigated by employing FTIR analysis. Thickness of the SiO₂ layer was investigated through transmission electron microscopy and it was identified to be ～10–23 nm over nanocrystalline NiFe₂O₄ particles. The magnetic behavior of pristine and surface modified NiFe₂O₄ particles were investigated using vibrating sample magnetometer (VSM). Magnetic studies showed the retention of magnetic property of surface modified NiFe₂O₄ particles with the reduced saturation magnetization and coercivity compared to the pristine NiFe₂O₄ particles, which is respectively due to the lower fraction of the magnetic component and the formation of interfacial structure.     

Densification and alloying of ball milled Silicon-Germanium powder mixture during spark plasma sintering

In this research, the influence of process parameters such as sintering temperature and current during alloying and densification of silicon-germanium (Si₈₀-Ge₂₀) powder mixture using spark plasma sintering (SPS) was reported. Si₈₀-Ge₂₀ powder mixture was consolidated at the temperature range 900–1200 °C with 40 MPa pressure for 5 min. soaking. X-ray diffraction (XRD) study was made on sintered compacts to confirm the Si(Ge) alloy formation. Scanning electron microscope (SEM) was used to understand the morphology, particle size and distribution of un-milled and milled Si₈₀-Ge₂₀ powder mixture. Transmission electron microscope (TEM) study was made on milled Si₈₀-Ge₂₀ powder mixture and bulk SiGe alloy to confirm the nano-crystallinity and alloy formation. Fracture toughness of sintered bulk SiGe alloy was determined from Palmqvist cracks geometry model using Vickers hardness testing. It is understood that, during spark plasma sintering nano-structured Si₈₀-Ge₂₀ powder simultaneously increases the densification and reaction kinetics. It helps to achieve homogenous nanostructured SiGe alloy of near theoretical density. The superior hardness and benchmarked fracture toughness (K_IC) values of 630 VHN and 2.19 MPa√m was achieved for SiGe alloy sintered at 1200 °C, respectively.     

Switching Transient Analysis and Characterization of an E-Mode B-Doped GaN-Capped AlGaN DH-HEMT with a Freewheeling Schottky Barrier Diode (SBD)

Journal of Electronic Materials - This paper presents a systematic study of Al0.23Ga0.77N/GaN/AlxGa1?xN double-heterojunction high-electron-mobility transistors (DH-HEMTs) with a boron-doped...     

Fabrication of Arothron stellatus skin collagen film incorporated with Coccinia grandis as a durable wound construct

The wound dressing material has been fabricated with the novel Arothron stellatus fish skin collagen scaffold loaded with a bioactive extract obtained from Coccinia grandis (CPE) and drug Ciprofloxacin (D). The collagen scaffold was fabricated from the nonedible solid waste of marine origin (a cheaper source of raw material). The in vitro fluorescence staining of cells and in vivo evaluation of the fabricated scaffold exhibited enhanced cell adhesion and proliferation and indicated a more efficient wound healing paradigm than that of the control and other treated groups, respectively. The increased collagen synthesis and re-epithelialization of wound are proved to be potential wound constructs.     

Microscopic,structural, and electrical characterization of the carbonaceous materials synthesized from various lignin feedstocks

Microscopic, structural and electrical characterization of the carbonaceous materials synthesized from different types of lignin precursors are investigated employing scanning electron microcopy (SEM), Raman spectroscopy, X‐ray diffraction, and AC conductivity techniques. Lignin precursors from various resources carbonized at 900°C for 6 h under nitrogen atmosphere are used for this study. SEM analysis indicates formation of various microstructures, which are highly influenced by the carbonization behavior of lignin feedstocks that varies with chemical composition as well as purity. Raman spectroscopy of the carbon materials shows significant variations of its features, which represents their unique carbonization behaviors and graphitization events. Clear understanding of peak intensity, shape, and area gave very different structural features influenced by their chemical environment of the chosen precursor lignins. Phase purity and the graphitization degree are investigated through their X‐ray diffraction patterns. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41786.     

Taguchi's approach for reliability and safety assessments in the stage separation process of a multistage launch vehicle

This paper presents in brief the formulation for lateral and longitudinal dynamics associated with the separation and pull out of an ongoing functional stage from the spent stage of a multistage launch vehicle using separation motors as jettisoning system. Taguchi method is employed to understand the influencing parameters in the separation process. It is possible to minimize the number of Monte-Carlo simulations (MCS) by Taguchi's orthogonal array. Statistical analysis has been carried out to identify the probability distribution function (PDF) for reliability and safety assessment of the stage separation system. The tolerances on the pull out time, relative velocity, lateral gap and longitudinal clearances between the separating bodies are taken into account while examining the non-occurrence of collision between the separating bodies. Lateral gap/dynamic clearance between stages are found to be very vital from collision aspects. This study clearly demonstrates the applicability of Taguchi method to capture the essential Monte-Carlo simulation results in the stage separation process. The method of approach followed in this study will be useful to understand the dynamic behavior of the separating bodies during the stage separation process of multistage launch vehicles.