CdS:Mn nanorods: solvothermal synthesis and properties

Manganese (0.05-9 mol.%) doped CdS nanorods were synthesized via solvothermal route using ethylenediamine (En) and a mixture of En and water as the solvents. The diameters and the lengths of the doped CdS nanorods varied from 40-100 nm and 600-2500 nm, respectively, with change in the composition of the solvents. The broad photoluminescence (PL) emission from the undoped CdS nanorods centered at approximately 535 nm is found to be blue shifted to 516 nm with the incorporation of Mn in the CdS crystal structure. Also increase in the intensity of the PL was noticed in the Mn doped CdS nanorods for both the solvent systems. Maximum PL intensity was observed for 1 mol.% Mn in case of En system and for 0.5 mol.% Mn in case of En/water system, above which quenching occurred as a result of Mn-Mn clustering. EPR study revealed six-line hyperfine splitting for low Mn concentration in both solvent systems. Increase in the Mn concentration caused EPR signal broadening due to Mn-Mn clustering.     

Investigation into the Cracking of Cross Members During Forming

An investigation into the cracking of cross members during forming from E-34 grade steel found that the cracking was a result of the presence of stringers of manganese sulfide inclusions, a high free nitrogen content, and a yield strength that was near the upper limit of the specified yield strength. A decrease in sulfur level and free nitrogen contents and a decrease in the yield strength were recommended as the measures to be taken to prevent such cracking.     

Silica encapsulated Ni nanoparticles: variation of optical and magnetic properties with particle size

Ni nanoparticles embedded in SiO2 matrix were prepared by sol-gel process. The molar percentages of Ni were varied from 2 to 20% of total SiO2 present in the matrix. Transmission electron microscope (TEM) images revealed that particle sizes varied from 8.0-15.7 nm at an annealing temperature of 773 K with variation of concentration. The optical absorption spectra revealed that the surface plasmon resonance (SPR) peak in the UV region of the spectrum shifted with the particle diameter (D) from that at 247.3 nm for D = 8.0 nm to 250.7 nm for D = 15.7 nm. In hysteresis loop measurements the magnetizations (M) of the nanocomposites also increased with higher Ni content in the matrix and did not saturate in the measuring limit of the magnetic filed (H) of 4 KOe. The anhysteric curves for different samples were analyzed with the law of approach to saturation (LAS). The zero field cooled (ZFC) and field cooled (FC) magnetization measurements at 50 Oe showed increasing broadening of the ZFC curve with the higher Ni content. To calculate the average blocking temperature ((T(B a distribution of the blocking temperatures (T(B)) was assumed to initiate theoretical fittings and it was found to be increasing with the Ni concentration in the matrix.     

Role of the C-terminal domain of Bax and Bcl-XL in their localization and function in yeast cells

It has been suggested that the C-terminal domain of Bcl-2 family members may contain a signal anchor sequence that targets these proteins to the mitochondrial outer membrane. We have investigated the consequence of deleting this domain upon cytochrome c release in yeast strains that coexpress truncated forms of Bax (i.e. BaxA) and Bcl-X(L) (i.e. Bcl-X(L)delta). We find that (i) Bax(delta) is as efficient as full-length Bax in promoting cytochrome c release, but Bcl-x(L)delta has remarkably reduced rescuing ability compared to full-length Bcl-x(L); (ii) full-length Bcl-X(L) protein acts by relocalizing Bax from the mitochondrial fraction to the soluble cytosolic fraction; (iii) Bax undergoes N-terminal cleavage when expressed in yeast, which is prevented by coexpression of Bcl-X(L), suggesting that Bcl-x(L) may mask the cleavage site of Bax through a direct physical interaction of the two proteins.     

Studies on the potential of coal fly ash as a heterogeneous catalyst in oxidation of aqueous sodium sulfide solutions with hydrogen peroxide

The potential of fly ash procured form coal-fired thermal power plants was studied as a heterogeneous catalyst in the oxidation of aqueous sodium sulfide solutions with hydrogen peroxide in the temperature range of 303–323 K. The effects of various parameters (source of fly ash, fly ash loading, initial concentrations of sodium sulfide and hydrogen peroxide, electrolyte and deactivation of catalytic effect of fly ash) were studied. For an initial sodium sulfide and hydrogen peroxide concentration of 26·98×10⁻² kmol m⁻³ and 24·28×10⁻² kmol m⁻³ respectively, only 4% (w/v) fly ash loading intensified the rate of oxidation by a factor of 4·52 over that without fly ash at 303 K. The deactivation of the catalytic effect of fly ash was found to be less than 20% even after six repeated uses. The kinetics of aqueous phase decomposition of hydrogen peroxide was also studied in the presence of fly ash in alkaline medium. ©1997 SCI     

In-situ crystal growth and photoluminescence properties of YBO3: Tb3+ microstructures

Three-dimensional (3D) YBO₃:Tb³⁺ flower-like and dense flower-like hierarchitecture constituted of nanoflakes are solvothermally synthesized in the presence of polyborate precursors in the mixture of ethanol and water. The growth process of the YBO₃:Tb³⁺ flowers and dense flowers was explored based on the time-dependent experiment and the results showed that the growth mechanism follows an in situ growth rather than self-assembly process as reported previously. YBO₃:Tb³⁺ morphologies composed of nanoflakes are achieved by controlling the concentration of ethanol and dependence of photoluminescence on morphology was studied. Remarkable photoluminescence enhancement was observed for YBO₃:Tb³⁺ with flower-like morphology demonstrating the potential of the microstructure in future applications as a green phosphor. Such a synthetic method and growth mechanism may be applied to fabricate complex 3D architectures of other materials.     

Structural,microstructural, and thermal characterizations of a chalcopyrite concentrate from the Singhbhum shear zone,India

The structural and morphological characterizations of a chalcopyrite concentrate, collected from the Indian Copper Complex, Ghatshila, India, were carried out by X-ray diffraction, scanning electron mi...     

Secured secret sharing technique based on chaotic map and DNA encoding with application on secret image

This paper shows a secured key-based (k, n) threshold cryptography scheme, where key as well as secret data is shared among set of participants. In this scheme, each share has some bytes missing and these missing bytes can be recovered from a set of exactly k shares, but not less than k. Therefore, each share contains partial secret information which is also encrypted by DNA encoding scheme. Additionally, this paper introduces a concept, where each share information size is varied. More precisely, each share contains a different percentage of secret information and which is strongly dependent on the key. Moreover key sensitivity analysis and statistical analysis prove the robustness against different cryptanalysis attacks and thus ensures high acceptability for information security requirements.     

An MLP-based texture segmentation method without selecting a feature set

A texture segmentation technique which employs a multilayer perceptron (MLP) and does not consider the selection of features is presented in this paper. Thus, users can avoid selection and computation of the feature set and hence real-time segmentation may be possible. The technique apparently works in a fashion similar to our visual system whereby we do not consciously compute any feature for texture discrimination. A detailed study has been made for the selection of the network size. A newly proposed variant of the back-propagation algorithm has been used for more efficient training of the network. An edge-preserving noise-smoothing approach has been proposed to remove noise from the segmented image.