Efficient visible light photocatalytic activity and enhanced stability of BiOBr/Cd(OH)(2) heterostructures

Novel BioBr/Cd(OH)(2) heterostructures were synthesized by a facile chemical bath method under ambient conditions. A series of BiOBr/Cd(OH)(2) heterostructures were obtained by tuning the Bi/Cd molar ratios. The obtained heterostructures were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). Optical properties were studied by UV-visible spectroscopy, diffuse reflectance spectroscopy and photoluminescence (PL). Photocatalytic studies on rhodamine B (RhB) under visible light irradiation showed that the heterostructures are very efficient photocatalysts in mild basic medium. Scavenger test studies confirmed that the photogenerated holes and superoxide radicals (O-2(center dot-)) are the main active species responsible for RhB degradation. Comparison of photoluminescence (PL) intensity suggested that an inhibited charge recombination is crucial for the degradation process over these photocatalysts. Moreover, relative positioning of the valence and conduction band edges of the semiconductors, O-2/O-2(center dot-) and (OH)-O-center dot/H2O redox potentials and HOMO-LUMO levels of RhB appear to be responsible for the hole-specificity of degradation. Photocatalytic recycling experiments indicated the high stability of the catalysts in the reaction medium without any significant loss of activity. This study hence concludes that the heterojunction constructed between Cd(OH)(2) and BiOBr interfaces play a crucial role in influencing the charge carrier dynamics and subsequent photocatalytic activity.

Influence of soil pedological properties on termite mound stability

This study investigated the influence of soil properties on the density and shape of epigeous fungus-growing termite nests in a dry deciduous forest in Karnataka, India. In this environment, Odontotermes obesus produces cathedral shaped mounds. Their density, shape (height and volume) and soil physicochemical properties were analyzed in ferralsol and vertisol environments. No significant difference was observed in O. obesus mound density (n = 2.7 mound ha(-1) on average in the vertisol and ferralsol areas). This study also showed that O. obesus has a limited effect on soil physical properties. No differences in soil particle size, pH, or the C:N ratio and base saturation were measured whereas the C and N contents were reduced and CEC was higher in termite nest soils in both environments. Clay mineralogical composition was also measured, and showed the presence of higher amounts of smectite clays in termite nest soils, which thus explained the increasing CEC despite the reduced C and N content. However, the main difference was the shape of the termite mounds. The degradation of the nests created a hillock of eroded soil at the base of termite mounds in the vertisol while only a thin layer of eroded soil was observed in the ferralsol. The increased degradation of termite mounds in the vertisol is explained by the presence of smectites (2:1 swelling clays), which confer macroscopic swelling and shrinking characteristics to the soil. Soil shrinkage during the dry season leads to the formation of deep cracks in the termite mounds that allow rain to rapidly penetrate inside the mound wall and then breakdown unstable aggregates. In conclusion, it appears that despite a similar abundance, termite mound properties depend to a large extent on the soil properties of their environments. (C) 2015 Elsevier B.V. All rights reserved.

Stability analysis of thick piezoelectric metal based FGM plate using first order and higher order shear deformation theory

This paper presents the stability analysis of functionally graded plate integrated with piezoelectric actuator and sensor at the top and bottom face, subjected to electrical and mechanical loading. The finite element formulation is based on first order and higher order shear deformation theory, degenerated shell element, von-Karman hypothesis and piezoelectric effect. The equation for static analysis is derived by using the minimum energy principle and solutions for critical buckling load is obtained by solving eigenvalue problem. The material properties of the functionally graded plate are assumed to be graded along the thickness direction according to simple power law function. Two types of boundary conditions are used, such as SSSS (simply supported) and CSCS (simply supported along two opposite side perpendicular to the direction of compression and clamped along the other two sides). Sensor voltage is calculated using present analysis for various power law indices and FG (functionally graded) material gradations. The stability analysis of piezoelectric FG plate is carried out to present the effects of power law index, material variations, applied mechanical pressure and piezo effect on buckling and stability characteristics of FG plate.

Mapping Key Residues of ISD11 Critical for NFS1-ISD11 Subcomplex Stability IMPLICATIONS IN THE DEVELOPMENT OF MITOCHONDRIAL DISORDER, COXPD19

Biogenesis of the iron-sulfur (Fe-S) cluster is an indispensable process in living cells. In mammalian mitochondria, the initial step of the Fe-S cluster assembly process is assisted by the NFS1-ISD11 complex, which delivers sulfur to scaffold protein ISCU during Fe-S cluster synthesis. Although ISD11 is an essential protein, its cellular role in Fe-S cluster biogenesis is still not defined. Our study maps the important ISD11 amino acid residues belonging to putative helix 1 (Phe-40), helix 3 (Leu-63, Arg-68, Gln-69, Ile-72, Tyr-76), and C-terminal segment (Leu-81, Glu-84) are critical for in vivo Fe-S cluster biogenesis. Importantly, mutation of these conserved ISD11 residues into alanine leads to its compromised interaction with NFS1, resulting in reduced stability and enhanced aggregation of NFS1 in the mitochondria. Due to altered interaction with ISD11 mutants, the levels of NFS1 and Isu1 were significantly depleted, which affects Fe-S cluster biosynthesis, leading to reduced electron transport chain complex (ETC) activity and mitochondrial respiration. In humans, a clinically relevant ISD11 mutation (R68L) has been associated in the development of a mitochondrial genetic disorder, COXPD19. Our findings highlight that the ISD11 R68A/R68L mutation display reduced affinity to form a stable subcomplex with NFS1, and thereby fails to prevent NFS1 aggregation resulting in impairment of the Fe-S cluster biogenesis. The prime affected machinery is the ETC complex, which showed compromised redox properties, causing diminished mitochondrial respiration. Furthermore, the R68L ISD11 mutant displayed accumulation of mitochondrial iron and reactive oxygen species, leading to mitochondrial dysfunction, which correlates with the phenotype observed in COXPD19 patients.

Effect of Surface Energy Anisotropy on the Stability of Growth Fronts in Multiphase Alloys

Eutectic growth offers a variety of examples for pattern formation which are interesting both for theoreticians as well as experimentalists. One such example of patterns is ternary eutectic colonies which arise as a result of instabilities during growth of two solid phases. Here, in addition to the two major components being exchanged between the solid phases during eutectic growth, there is an impurity component which is rejected by both solid phases. During progress of solidification, there develops a boundary layer of the third impurity component ahead of the solidification front of the two solid phases. Similar to Mullins-Sekerka type instabilities, such a boundary layer tends to make the global solidification envelope unstable to morphological perturbations giving rise to two-phase cells. This phenomenon has been studied numerically in two dimensions for the conditions of directional solidification, by Plapp and Karma (Phys Rev E 66:061608, 2002) using phase-field simulations. While, in the work by Plapp and Karma (Phys Rev E 66:061608, 2002) all interfaces are isotropic, in our presentation, we extend the phase-field model by considering interfacial anisotropy in the solid-solid and solid-liquid interfaces and characterize the role of interfacial anisotropy on the stability of the growth front through phase-field simulations in two dimensions.