Minimally invasive injectable short nanofibers of poly(glycerol sebacate) for cardiac tissue engineering

Myocardial tissue lacks the ability to appreciably regenerate itself following myocardial infarction (MI) which ultimately results in heart failure. Current therapies can only retard the progression of disease and hence tissue engineering strategies are required to facilitate the engineering of a suitable biomaterial to repair MI. The aim of this study was to investigate the in?vitro properties of an injectable biomaterial for the regeneration of infarcted myocardium. Fabrication of core/shell fibers was by co-axial electrospinning, with poly(glycerol sebacate) (PGS) as core material and poly-l-lactic acid (PLLA) as shell material. The PLLA was removed by treatment of the PGS/PLLA core/shell fibers with DCM:hexane (2:1) to obtain PGS short fibers. These PGS short fibers offer the advantage of providing a minimally invasive injectable technique for the regeneration of infarcted myocardium. The scaffolds were characterized by SEM, FTIR and contact angle and cell-scaffold interactions using cardiomyocytes. The results showed that the cardiac marker proteins actinin, troponin, myosin heavy chain and connexin 43 were expressed more on short PGS fibers compared to PLLA nanofibers. We hypothesized that the injection of cells along with short PGS fibers would increase cell transplant retention and survival within the infarct, compared to the standard cell injection system.     

Correlation Between Charge, Spin and Lattice in La–Eu–Sr Manganites

To understand the structural, electrical, magnetic, elastic and anelastic properties of La_0.67?x Eu _x Sr_0.33MnO₃ (0.30≤x≤0.39) manganites, a series of samples was prepared by citrate gel route. X-ray diffraction studies along with Rietveld analysis indicate the samples crystallize in single phase with Pnma space group. Studies on the variations of magnetization with temperature indicate that the Curie transition temperature (T _C) decreases with increasing Eu content. Furthermore, Eu substitution is found to increase the electrical resistivity and significantly enhances the colossal magnetoresistance effect, while it is found to decrease the characteristic metal–insulator transition temperature (T _P). On analyzing the electrical resistivity data, it has been concluded that the resistivity below T _P can be explained based on electron–electron, electron–phonon and two magnon scattering processes, while that above T _P, the adiabatic small polaron model is found to explain the observed behavior. Finally, the longitudinal modulus (L) and internal friction (Q ^?1) have been measured and a dramatic change in L (T) is observed at T _C, accompanied by a sharp peak in Q ^?1 (T). Simultaneous occurrence of magnetic, transport and lattice anomalous behavior at T _C indicate the presence of strong electron–phonon and spin–phonon interactions in these manganites.     

Photovoltaic device performance of single-walled carbon nanotube and polyaniline films on n-Si: device structure analysis

In this paper, we explore the use of two organic materials that have been touted for use as photovoltaic (PV) materials: inherently conducting polymers (ICPs) and carbon nanotubes (CNTs). Due to these materials' attractive features, such as environmental stability and tunable electrical properties, our focus here is to evaluate the use of polyaniline (PANI) and single wall carbon nanotube (SWNT) films in heterojunction diode devices. The devices are characterized by electron microscopy (film morphology), current-voltage characteristics (photovoltaic behavior), and UV/visible/NIR spectroscopy (light absorption). We have found that both PANI and SWNT can be utilized as photovoltaic materials in a simple bilayer configuration with n-type Silicon: n-Si/PANI and n-Si/SWNT. It was our aim to determine how photovoltaic performance was affected utilizing both PANI and SWNT layers in multilayer devices: n-Si/PANI/SWNT and n-Si/SWNT/PANI. The short-circuit current density increased from 4.91 mA/cm(2) (n-Si/PANI) to 12.41 mA/cm(2) (n-Si/PANI/SWNT), while an increase in power conversion efficiency by ~91% was also observed. In the case of n-Si/SWNT/PANI and its corresponding device control (n-Si/SWNT), the short-circuit current density was decreased by an order of magnitude. The characteristics of the device were affected by the architecture and the findings have been attributed to the more effective transport of holes from the PANI to SWNT and less effective transport of holes from PANI to SWNT in the respective multilayer devices.     

A novel low temperature integration of hybrid CMOS devices on flexible substrates

In this work we demonstrate a novel integration approach to fabricate CMOS circuits on plastic substrates (poly-ethylene naphthalate, PEN). We use pentacene and amorphous silicon (a-Si:H) thin-film transistors (TFTs) as p-channel and n-channel devices, respectively. The maximum processing temperature for n-channel TFTs is 180 °C and 120 °C for the p-channel TFTs. CMOS circuits demonstrated in this work include inverters, NAND, and NOR gates. Carrier mobilities for nMOS and pMOS after the CMOS integration process flow are 0.75 and 0.05 cm²/V s, respectively. Threshold voltages (V_t) are 1.14 V for nMOS and −1.89 V for pMOS. The voltage transfer curve of the CMOS inverter showed a gain of 16. Correct logic operation of integrated flexible NAND and NOR CMOS gates is also demonstrated. In addition, we show that the pMOS gate dielectric is likely failing after electrical stress.     

Purified mesoporous nickel metal organic framework as electrocatalyst for hydrogen evolution reaction (HER) in basic medium

Metal organic framework or MOFs are found to be a good catalyst for hydrogen evolution in view of its excellent structural features like porous nature and well-defined morphology. This report describes the synthesis of Nickel-MOF prepared by solvothermal approach and further purified by a chemical process. Both impure and purified Nickel-MOFs are fabricated as electrodes for evaluating HER reaction. The performance towards electrocatalytic activity is affected due to the impurities present in the porous structure. In view of investigating the effect of activation/purification process towards morphology and in-turn HER activity, activation and purification is carried out to enhance the performance of MOFs. The electrochemical characterization proves high electrocatalytic activity for purified Ni-MOF with high rate kinetics towards HER than impure Ni-MOF. The Tafel slope of purified Nickel MOF is estimated to be 73.7 mV/dec with a low charge transfer resistance of 1.84 Ω, whereas the unpurified Ni-MOF shows 87.47 mV/dec and 3.85 Ω. Results show that pure Ni-MOF has abundant catalytic active edge sites and obeys Volmer-Heyrvosky mechanism with makes desorption of hydrogen as rate determining step.     

Design and Implementation of Hybrid Compression Algorithm for Personal Health Care Big Data Applications

Wireless Personal Communications - Advanced telemedicine requires the gathering of big data through wireless body area network or internet of things based applications. These networks perform...     

Metallurgical Analysis of Cracked Redundant Valves for Propellant Flow Control in the Attitude Orbital Control System of a Satellite

Attitude Orbital Control System (AOCS) thrusters, used in Indian satellites employ Latchable Series Redundant Valves (LSRV) for propellant flow control. The valve body has a major component called bobbin, which comprises four parts, three parts made of AISI 304L stainless steel and one part of AISI 446 stainless steel. About 150 bobbins were electron beam welded and one, from a group of thirty bobbins, developed a crack in the HAZ of one of the face welds. Detailed analysis revealed that the crack was due to stress-assisted cracking phenomenon. The stress induced by press fitting of a part in between other two parts of valve was primarily responsible for the cracking.     

Synthesis of MnWO4 nanorods and its electrical and electrochemical properties

The MnWO₄ nanorods were successfully synthesized by surfactant assisted ultrasonics method and characterized its structural (XRD), morphological (SEM) electrical (solid state impedance) and electrochemical (CV) properties. The X-ray diffraction patterns inferred the formation of highly crystalline monoclinic structure of MnWO₄. The formation of nanorods with the aspect ratios of 30–40?nm were reveals from SEM image. The maximum d.c. electrical conductivity was found to be 4.40?×?10^?5?S/cm at 570°C for MnWO₄ nanorods prepared by surfactant assisted ultrasonic method. The quasi-rectangular behavior of cyclic voltammogram inferred the supercapacitive behavior of the prepared MnWO₄ nanorods.     

Sol–Gel Synthesis and Formation Mechanism of Ultrahigh Temperature Ceramic: HfB2

Hafnium diboride (HfB₂) powder has been synthesized via a sol–gel‐based route using phenolic resin, hafnium chloride, and boric acid as the source of carbon, hafnium, and boron, respectively, though a small number of comparative experiments involved amorphous boron as boron source. The effects of heat‐treatment dwell time and hafnium:carbon (Hf:C) and hafnium:boron (Hf:B) molar ratio on the purity and morphology of the final powder have been studied and the mechanism of HfB₂ formation investigated using several techniques. The results showed that while temperatures as low as 1300°C could be used to produce HfB₂ particles, the heat treatment needed to last for about 25 h. This in turn resulted in anisotropic particle growth along the c‐axis of the HfB₂ crystals yielding tube‐like structures of about 10 μm long. Equiaxed particles 1–2 μm in size were obtained when the precursor was heat treated at 1600°C for 2 h. The reaction mechanism involved boro/carbothermal reduction and the indications were that the formation of HfB₂ at 1300°C is through the intermediate formation of an amorphous B or boron suboxides, although at higher temperatures more than one reaction mechanism may be active.     

Ecofriendly geopolymer concrete: a comprehensive review

Clean Technologies and Environmental Policy - After ordinary Portland cement (OPC) concrete, geopolymer concrete (GPC) is the most advanced form of concrete. GPC has many advantages including...