Synthesis,Structural, and Magnetic Properties of Nanocrystalline Ti 0.95Co0.05O2-Diluted Magnetic Semiconductors

With a view to investigate the influence of nanometric size on the structural, surface, and magnetic properties of nanocrystalline Ti_0.95Co_0.05O₂-diluted magnetic semiconductors, prepared by a novel simple controllable peroxide-assisted reflux chemical route followed by annealing at different temperatures, a systematic investigation has been undertaken. Structural characterizations such as X-ray diffraction followed by Rietveld refinement, electron diffraction pattern, Fourier transform infrared, Raman scattering, and X-ray photoelectron spectroscopy (XPS) measurements have shown anatase phase formation in nanocrystalline Ti_0.95Co_0.05O₂ without any additional impurity phases. The modified reflux chemical route was effective in obtaining pure phase Ti_0.95Co_0.05O₂ nanoparticles. Surface morphological investigations by using transmission electron microscopy and atomic force microscopy measurements showed the predominant effect of random distribution of nanoparticles on the aggregation behavior and local microstructural changes. The deconvoluted XPS core level Co 2p spectral study manifested the oxidation state of Co as + 2 and is found to be stable with varying particle size and annealing temperature. The ferromagnetic behavior was investigated by vibrating sample magnetometer, magnetic force microscopy, and electron spin resonance measurements. These magnetization studies showed all the samples are ferromagnetic at room temperature without any magnetic clusters. The correlation between structure, surface condition of the nanoparticles and local electronic interactions, and magnetization of the samples was analyzed and explored the origin of ferromagnetism.     

Purification,characterisation and application of α‐l‐rhamnosidase from Penicillium citrinum MTCC‐8897

An α‐l ‐rhamnosidase secreted by Penicillium citrinum MTCC‐8897 has been purified to homogeneity from the culture filtrate of the fungal strain using ammonium sulphate precipitation and cation‐exchange chromatography on carboxymethyl cellulose. The sodium dodecyl sulphate/polyacrylamide gel electrophoresis analysis of the purified enzyme gave a single protein band corresponding to the molecular mass 51.0 kDa. The native polyacrylamide gel electrophoresis also gave a single protein band confirming the enzyme purity. The K_m and V_max values of the enzyme for p‐nitrophenyl α‐l ‐rhamnopyranoside were 0.36 mm and 22.54 μmole min^?1 mg^?1, respectively, and k_cat value was 17.1 s^?1 giving k_cat/K_m value of 4.75 × 10⁴ m ^?1 s^?1. The pH and temperature optima of the enzyme were 7.0 and 60 °C, respectively. The purified enzyme liberated l ‐rhamnose from naringin, rutin, hesperidin and wine, indicating that it has biotechnological application potential for the preparation of l ‐rhamnose and other pharmaceutically important compounds from natural glycosides containing terminal α‐l ‐rhamnose and also in the enhancement of wine aroma.     

Influence of microstructural inhomogeneities on the fracture toughness of modified 9Cr–1Mo steel at 298–823 K

Quasistatic fracture behaviour of two heats of modified 9Cr–1Mo steel for steam generator applications have been assessed at 298, 653 and 823 K. J–R curves were established and the elastic–plastic fracture toughness values at 0.2 mm crack extension (J_0.2) were determined. The fracture mechanisms were entirely different for the two steels at 298 K, with brittle fracture controlled by cleavage crack initiation in one and ductile fracture in the other by void nucleation and growth. At 653 and 823 K, fracture in both materials was by ductile crack growth. The difference in behaviour between the two steels at 298 K was attributed to the differences in microstructure, distribution and density of inclusions as well as phosphorous contents.     

Fabrication and characterization of nanostructured (Sn–Ti)O<Subscript>2</Subscript> pellets and films for liquefied petroleum gas sensing

Present paper reports the synthesis of nanostructured (Sn–Ti)O₂ via physicochemical method, its characterization and performance as liquefied petroleum gas (LPG) sensor. The synthesized material was characterized using XRD that confirmed the formation of (Sn–Ti)O₂ nanocomposite. Minimum crystallite size was found as 7 nm. The material was also investigated through SEM, DSC, FTIR, PL and UV–Vis spectrophotometer. Further, the pellet, thick and thin films were fabricated for the sensing analysis. Pellets (9 mm diameter, 4 mm thickness) of (Sn–Ti)O₂ nanocomposite were made by hydraulic pressing machine by applying uniaxial pressure of 616 MPa, thick films (thickness ~2 µm) were made by screen printing technique and thin films were prepared using a Photo resist spinner unit. Further at room temperature, the pellet and films were exposed to LPG in a gas chamber under controlled conditions at room temperature and variations in resistance with the concentrations of LPG were observed. The maximum value of sensitivity of solid state pellet, thick and thin films based sensors were found 7, 9 and 39 for 5 vol% of LPG, respectively. Sensing characteristics were found to be reproducible, after 6 months of their fabrication, indicating the stability of the sensors.     

Reactive flash sintering: MgO and α-Al2O3 transform and sinter into single-phase polycrystals of MgAl2O4

We show that flash experiments with three phase mixed-powders of yttria-stabilized zirconia (8YSZ), MgO, and α-Al₂O₃ not only produce polycrystals of high density, but also the transformation of magnesia and alumina into single-phase spinel. The presence of zirconia facilitates the onset of the flash. The sintering experiments in the laboratory were extended to live experiments at the National Synchrotron Light Source II at Brookhaven National Laboratory in order to measure the time-dependent evolution of single-phase spinel. The phase transformation occurred in <3 seconds during Stage II. Later, during Stage III the cubic zirconia transformed partly into the monoclinic phase, which reverted back to the cubic phase when the flash was extinguished by turning off the current to the specimen. The results underpin a recent report on the synthesis of single-phase bismuth ferrite from constituent oxides in reactive flash experiments, raising the specter of flash as a method for synthesis as well as sintering of complex oxide ceramics. The role of zirconia in catalyzing the flash in the present study is discussed.     

A Chaucer microstrip fractal antenna for mobile applications

In this paper a Chaucer fractal patch antenna integrated with split ring structure is simulated using Ansoft’s (HFSS), as well as fabricated and tested using VNA. The obtained results indicate that the proposed antenna resonates at 2.4 GHz in the ISM band. In addition, the structure offers multi-band operation with the fair value of return loss, gain, and bandwidth, impedance and directivity in the entire range of frequency operation.     

Neural network and GMM based feature mappings for consonant–vowel recognition in emotional environment

In this work, we propose a mapping function based feature transformation framework for developing consonant–vowel (CV) recognition system in the emotional environment. An effective way of conveying messages is by expressing emotions during human conversations. The characteristics of CV units differ from one emotion to other emotions. The performance of existing CV recognition systems is degraded in emotional environments. Therefore, we have proposed mapping functions based on artificial neural network and GMM models for increasing the accuracy of CV recognition in the emotional environment. The CV recognition system has been explored to transform emotional features to neutral features using proposed mapping functions at CV and phone levels to minimize mismatch between training and testing environments. Vowel onset and offset points have been used to identify vowel, consonant and transition segments. Transition segments are identified by considering initial 15% speech samples between vowel onset and offset points. The average performance of CV recognition system is increased significantly using feature mapping technique at phone level in three emotional environments (anger, happiness, and sadness).     

Effect of hydrophilic and hydrophobic polymers on permeation of S-amlodipine besylate through intercalated polymeric transdermal matrix: 3(2) designing,optimization and characterization

Objective: Innovation in material science has made it possible to fabricate a pharmaceutical material of modifiable characteristics and utility, in delivering therapeutics at a sustained/controlled rate. The objective of this study is to design and optimize the controlled release transdermal films of S-Amlodipine besylate by intercalating hydrophilic and hydrophobic polymers.

Methods: 3(2) factorial design and response surface methodology was utilized to prepare formulations by intercalating the varied concentration of polymers(A) and penetration enhancer(B) in solvent. The effect of these independent factors on drug release and flux was investigated to substantiate the ex-vivo, stability and histological findings of the study.

Results: FTIR, DSC revealed the compatibility of drug with polymers; however, the semicrystallinity in drug was observed under PXRD. SEM micrographs showed homogeneous dispersion and entanglement of drug throughout the matrix. Results from the permeation study suggested the significant effect of factors on the ex vivo permeation of drug. It was observed that drug release was found to be increased with an increase in hydrophilic polymer concentration and PE. The formulations having polymers (EC:PVPK-30) at 7:3 showed maximum drug release with highest flux (102.60?±?1.12?µg/cm²/h) and permeability coefficient (32.78?±?1.38?cm/h). Significant effect of PE on lipid and protein framework of the skin was also observed which is responsible for increased permeation. The optimized formulation was found to be stable and showed no-sign of localized reactions, indicating safety and compatibility with the skin.

Conclusion: Thus, results indicated that the prepared intercalated transdermal matrix can be a promising nonoral carrier to deliver effective amounts of drug.