Multifunctional mussel-inspired Gelatin and Tannic acid-based hydrogel with pH-controllable release of vitamin B12

Hydrogels have emerged to be an impeccable material for a large variety of applications over the past few decades. In the field of biomedical applications, remarkable progress has been observed in the effort of fabricating numerous hydrogel systems. In this work, gelatin and tannic acid-based stretchable and adhesive hydrogel has been synthesized to study the release behavior of vitamin B₁₂. Successful formation of the synthesized hydrogels was confirmed by Fourier transform infrared and X-ray diffraction analysis. The morphology of the surfaces and the cross section of such hydrogels were studied with Scanning electron microscopy analysis. Swelling behavior of our hydrogel was studied with Design Expert software. The maximum swelling of the hydrogel was found to be around 137 g/g. Adhesive property was demonstrated on various surfaces to observe the adhesiveness of the fabricated hydrogel. Blood compatibility study was also performed. The release behavior of vitamin B₁₂ was performed in two different pH media and it was found to have enhanced value in the fluid mimicking the intestine. This work provides a new prospect for designing hydrogels with stretchable and adhesive properties with pH-controllable drug delivery applications along with other promising applications in various fields of research.     

Raman spectra,photoluminescence and ferromagnetism of pure,Co and Fe doped SnO2 nanoparticles

The pure and transition metal (Co and Fe = 3 and 5 mol%) doped SnO₂ nanoparticles have been synthesized by a chemical route using polyvinyl alcohol as surfactant. These nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, Fourier transform infrared (FTIR) spectroscopy, photoluminescence (PL) and magnetic measurements. The XRD patterns show that all the samples have tetragonal rutile structure without any extra phase and the value of average particle size using FWHM lies within 12–29 nm is also confirmed by TEM. FTIR spectrum has been used to confirm the formation of SnO bond. Raman spectroscopy shows the intensity loss of classical cassiterite SnO₂ vibration lines which is an indication of significant structural modifications. From PL, an intense blue luminescence centered at a wavelength ～530 nm is observed in the prepared SnO₂ nanoparticles, which is different from the yellow-red light emission observed in SnO₂ nanostructures prepared by other methods. The strong blue luminescence from the as-grown SnO₂ nanoparticles is attributed to oxygen-related defects that have been introduced during the growth process. These Co and Fe-doped SnO₂ nanoparticles exhibit room temperature ferromagnetism and the value of their magnetic moment and phase transition temperature are sensitive to their size and stoichiometric ratio.     

Time Compression Multiplexing for Loop Transmission of Speech Signals

This paper considers the use of time compression multiplexing (TCM) for telephone loop communications. The analysis treats TCM transmission degradations in general, and applies the results to telephone speech transmission. To gain an understanding of the nature of TCM degradations, transmission through a linear, time invariant network and demultiplexing is considered. The channel signals are then assumed to be wide-sense stationary random processes, and expressions for the spectral properties of the TCM distortion and interchannel crosstalk are determined. To accurately evaluate the performance of a TCM system, a practical and economical equalizer is proposed. It is designed to meet speech transmission requirements for the telephone loop plant. A worst case application is chosen to evaluate the system performance. The evaluation of the TCM transmission performance utilizes both the random signal model and a computer simulation using digitized speech. The random signal analysis shows that the spectra of the distortion and crosstalk are significant for human speech. Results of the digitized speech simulation demonstrate that the subjective effect of the signal distortion is not severe, but the crosstalk is somewhat intelligible and more severe than expected.     

Defense Against Spectrum Sensing Data Falsification Attacker in Cognitive Radio Networks

Wireless Personal Communications - Cognitive radio is an empowering innovation that guarantees to achieve spectrum utilization. To manage the muddled wireless condition, cooperative spectrum...     

A study of finite size effects on cracked 2-D piezoelectric media using extended finite element method

The extended finite element method is applied on the two-dimensional (2-D) finite piezoelectric media weakened by a crack. The fourfold standard enrichment functions are taken in conjugation with the interaction integral to evaluate the intensity factors. Four sequence of analysis, namely crack–mesh alignment, aspect ratio, mesh with local refinement and domain independency is done on the center and edge crack problems. These four analyses when combined together give an optimum result to study the finite specimen. It is observed that for smaller values of strip width to crack length ratio the finiteness of the specimen size affects the intensity factors.     

Theoretical model on the electronic properties of multi-element AB5-type metal hydride

Nowadays, multi-element alloys are preferred over binary alloys for application point of view. The hydrogenation properties strongly depend on the thermodynamic, structural and electronic properties of the alloys. At present, no model is available which can predict the hydrogen storage properties of the multi-element alloy, before actual synthesis of the alloy. In the present investigation, efforts are made to develop a theoretical mathematical model to predict the hydrogenation properties of multi-element AB₅-type metal hydride. The present investigation deals with the various electronic parameters which may affect the hydrogenation characteristics of the metal hydride. Based on all such parameters, an electronic factor has been proposed for AB₅-type alloys. Electronic factor has been combined with the structural and thermodynamical factor to propose a new combined factor, which was further correlated with the hydrogen storage capacity of the alloy. Atomic radius and electronic configuration of substituted elements in the multi-element AB₅-type hydrogen storage alloy have been found as key players to predict the hydrogenation properties of the alloys before synthesis. It has been shown that in the case of alloy series with multiple substitutions, the combined factor is more relevant in deciding the hydrogen storage capacity in comparison to electronic factor alone. Combined factor is directly proportional to the hydrogen storage capacity. All the three factors thermodynamic, structural and electronic together may lead to the prediction of pressure-composition isotherm of the multi-element AB₅-type hydrogen storage alloy.     

Design of Fresnel lens with spherical facets for concentrated solar power applications

In this paper, a ray-tracing model is developed using MATLAB based on mathematical formulations used in the design of Fresnel lens with spherical facets. Further, a design chart for Fresnel lens with spherical facets is developed to determine aperture radius and design angle for a given focal length and focus size. Concentration ratio and spherical aberration for Fresnel lens with spherical facets are also compared with those of plano-convex lens and conventional Fresnel lens with triangular facets. Furthermore, the present mathematical model is validated with SolTrace model and with the experimental study conducted on a prototype of Fresnel lens with spherical facets fabricated using CO₂ laser cutting machine. Focal length for the proposed Fresnel lens with spherical facets is found to be the same. However, concentration ratio computed from the present ray-tracing model is in fair agreement with SolTrace model and experimental data with percentage deviations at focal length 5.4% and 12.4%, respectively.     

Multiferroic properties of Ba(FexTi1 − x)O3 nanorods

Multiferroic Ba(Fe_xTi_1 ? x)O₃ (BFT) nanorods were prepared by a chemical route using polyvinyl alcohol as surfactant. The presence of PVA in excess is responsible to convert cubic or spherical shaped nanoparticles into rodlike structure. Tetragonal phase and nano dimensions in the form of rods of BFT specimens are identified. These BFT nanorods show improvement in the coexistence of ferroelectricity and ferromagnetism of multiferroic properties than their nanoparticles. The effect of low dimensions of BFT rods to control dielectric constant with low loss up to higher frequency region has been observed. With 1% of Fe-doping BFT shows higher value of spontaneous polarization, saturation magnetization and dielectric constant than with other dopants.