Interplay of structural distortions, dielectric effects and magnetic order in multiferroic GdMnO3

Multiferroic materials are characterized by simultaneous magnetic and ferroelectric ordering making them good candidates for magneto-electrical applications. We conducted thermal expansion and magnetostriction measurements in magnetic fields up to 14 T on perovskitic GdMnO3 by highresolution capacitive dilatometry in an effort to determine all longitudinal and transversal components of the magnetostriction tensor. Below the ordering temperature T (N) = 42 K, i.e., within the different complex (incommensurate or complex) antiferromagnetic phases, lattice distortions of up to 100 ppm have been found. Although no change of the lattice symmetry occurs, the measurements reveal strong magneto-structural phenomena, especially in the incommensurate sinusoidal antiferromagnetic phase. A strong anisotropy of the magnetoelastic properties was found, in good agreement with the type and propagation vector of the magnetic structure. We demonstrate that our capacitive dilatometry can detect lattice expansion effects and changes of the dielectric permittivity simultaneously because the sample is housed inside the capacitor. A separation of both effects is possible by shielding the sample. Dielectric transitions could be detected by this method and compared to the critical values of H and T in the magnetic phase diagram. Dielectric changes measured at 1 kHz excitation frequency are detected in GdMnO3 at about 180 K, and between 10 K and 25 K in the canted antiferromagnetic structure which is characterized by a complex magnetic order on both the Gd- and Mn-sites.

New solid forms of the anti-HIV drug etravirine: salts, cocrystals, and solubility

Thirteen new solid forms of etravirine were realized in the process of polymorph and cocrystal/salt screening to improve the solubility of this anti-HIV drug. One anhydrous form, five salts (hydrochloride, mesylate, sulfate, besylate, and tosylate), two cocrystals (with adipic acid and 1,3,5-benzenetricarboxylic acid), and five solvates (formic acid, acetic acid, acetonitrile, and 2:1 and 1:1 methanolates) were obtained. The conformational flexibility of etravirine suggests that it can adopt four different conformations, and among these, two are sterically favorable. However, in all 13 solid forms, the active pharmaceutical ingredient (API) was found to adopt just one conformation. Due to the poor aqueous solubility of the API, the solubilities of the salts and cocrystals were measured in a 50% ethanol water mixture at neutral pH. Compared to the salts, the cocrystals were found to be stable and showed an improvement in solubility with time. All the salts were dissociated within an hour, except the tosylate, which showed 50% phase transformation after 1 h of the slurry experiment. A structure property relationship was examined to analyze the solubility behavior of the solid forms.

Intermolecular interactions, charge-density distribution and the electrostatic properties of pyrazinamide anti-TB drug molecule: an experimental and theoretical charge-density study

An experimental charge-density analysis of pyrazinamide (a first line antitubercular drug) was performed using high-resolution X-ray diffraction data (sin theta/lambda)(max) = 1.1 angstrom(-1)] measured at 100 (2) K. The structure was solved by direct methods using SHELXS97 and refined by SHELXL97. The total electron density of the pyrazinamide molecule was modeled using the Hansen-Coppens multipole formalism implemented in the XD software. The topological properties of electron density determined from the experiment were compared with the theoretical results obtained from CRYSTAL09 at the B3LYP/6-31G** level of theory. The crystal structure was stabilized by N-H center dot center dot center dot N and N-H center dot center dot center dot O hydrogen bonds, in which the N3-H3B center dot center dot center dot N1 and N3-H3A center dot center dot center dot O1 interactions form two types of dimers in the crystal. Hirshfeld surface analysis was carried out to analyze the intermolecular interactions. The fingerprint plot reveals that the N center dot center dot center dot H and O center dot center dot center dot H hydrogen-bonding interactions contribute 26.1 and 18.4%, respectively, of the total Hirshfeld surface. The lattice energy of the molecule was calculated using density functional theory (B3LYP) methods with the 6-31G** basis set. The molecular electrostatic potential of the pyrazinamide molecule exhibits extended electronegative regions around O1, N1 and N2. The existence of a negative electrostatic potential (ESP) region just above the upper and lower surfaces of the pyrazine ring confirm the pi-electron cloud.

Using heat treatment effects and EBSD analysis to tailor microstructure of hybrid Mg nanocomposite for enhanced overall mechanical response

In this study, a detailed investigation on the effect of heat treatment on the microstructural characteristics, texture evolution and mechanical properties of Mg-(5.6Ti+2.5B(4)C)(BM) hybrid nanocomposite is presented. Optimised heat treatment parameters, namely, heat treatment temperature and heat treatment time, were first identified through grain size and microhardness measurements. Initially, heat treatment of composites was conducted at temperature range between 100 and 300 degrees C for 1 h. Based on optical microscopic analysis and microhardness measurements, it was evident that significant grain growth and reduction in microhardness occurred for temperatures > 200 degrees C. The cutoff temperature that caused significant grain growth/matrix softening was thus identified. Second, at constant temperature (200 degrees C), the effect of variation of heat treatment time was carried out (ranging between 1 and 5 h) so as to identify the range wherein increase in average grain size and reduction in microhardness occurred. Furthering the study, the effect of optimised heat treatment parameters (200 degrees C, 5 h) on the microstructural texture evolution and hence, on the tensile and compressive properties of the Mg-(5.6Ti+2.5B(4)C)(BM) hybrid nanocomposite was carried out. From electron backscattered diffraction (EBSD) analysis, it was identified that the optimised heat treatment resulted in recrystallisation and residual stress relaxation, as evident from the presence of similar to 87% strain free grains, when compared to that observed in the non-heat treated/as extruded condition (i.e. 2.2 times greater than in the as extruded condition). For the heat treated composite, under both tensile and compressive loads, a significant improvement in fracture strain values (similar to 60% increase) was observed when compared to that of the non-heat treated counterpart, with similar to 20% reduction in yield strength. Based on structure-property correlation, the change in mechanical characteristics is identified to be due to: (1) the presence of less stressed matrix/reinforcement interface due to the relief of residual stresses and (2) texture weakening due to matrix recrystallisation effects, both arising due to heat treatment.

Seismotectonics of the April-May 2015 Nepal earthquakes: An assessment based on the aftershock patterns, surface effects and deformational characteristics

Occurrence of the April 25, 2015 (Mw 7.8) earthquake near Gorkha, central Nepal, and another one that followed on May 12 (Mw 7.3), located similar to 140 km to its east, provides an exceptional opportunity to understand some new facets of Himalayan earthquakes. Here we attempt to assess the seismotectonics of these earthquakes based on the deformational field generated by these events, along with the spatial and temporal characteristics of their aftershocks. When integrated with some of the post-earthquake field observations, including the localization of damage and surface deformation, it became obvious that although the mainshock slip was mostly limited to the Main Himalayan Thrust (MHT), the rupture did not propagate to the Main Frontal Thrust (MFT). Field evidence, supported by the available InSAR imagery of the deformation field, suggests that a component of slip could have emerged through a previously identified out-of-sequence thrust/active thrust in the region that parallels the Main Central Thrust (MCT), known in the literature as a co-linear physiographic transitional zone called PT2. Termination of the first rupture, triggering of the second large earthquake, and distribution of aftershocks are also spatially constrained by the eastern extremity of PT2. Mechanism of the 2015 sequence demonstrates that the out-of-sequence thrusts may accommodate part of the slip, an aspect that needs to be considered in the current understanding of the mechanism of earthquakes originating on the MHT. (c) 2015 Elsevier Ltd. All rights reserved.

Genomic amplification upregulates estrogen-related receptor alpha and its depletion inhibits oral squamous cell carcinoma tumors in vivo

The ESRRA gene encodes a transcription factor and regulates several genes, such as WNT11 and OPN, involved in tumorigenesis. It is upregulated in several cancers, including OSCC. We have previously shown that the tumor suppressor miR-125a targets ESRRA, and its downregulation causes upregulation of ESRRA in OSCC. Upregulation of ESRRA in the absence of downregulation of miR-125a in a subset of OSCC samples suggests the involvement of an alternative mechanism. Using TaqMan (R) copy number assay, here we report for the first time that the genomic amplification of ESRRA causes its upregulation in a subset of OSCC samples. Ectopic overexpression of ESRRA led to accelerated cell proliferation, anchorage-independent cell growth and invasion, and inhibited apoptosis. Whereas, knockdown of ESRRA expression by siRNA led to reduced cell proliferation, anchorage-independent cell growth and invasion, and accelerated apoptosis. Furthermore, the delivery of a synthetic biostable ESRRA siRNA to OSCC cells resulted in regression of xenografts in nude mice. Thus, the genomic amplification of ESRRA is another novel mechanism for its upregulation in OSCC. Based on our in vitro and in vivo experiments, we suggest that targeting ESRRA by siRNA could be a novel therapeutic strategy for OSCC and other cancers.