Dielectric relaxation and anti-ferromagnetic coupling of BiEu03 and BiGd03

BiEuO3 (BE) and BiGdO3 (BG) are synthesized by the solid-state reaction technique. Rietveld refinement of the X-ray diffraction data shows that the samples are crystallized in cubic phase at room temperature having Fm3m symmetry with the lattice parameters of 5.4925(2) and 5.4712(2) A for BE and BG, respectively. Raman spectra of the samples are investigated to obtain the phonon modes of the samples. The dielectric properties of the samples are investigated in the frequency range from 42 Hz to 1.1 MHz and in the temperature range from 303 K to 673 K. An analysis of the real and imaginary parts of impedance is performed assuming a distribution of relaxation times as confirmed by the Cole-Cole plots. The frequency-dependent maxima in the loss tangent are found to obey an Arrhenius law with activation energy similar to 1 eV for both the samples. The frequency-dependent electrical data are also analyzed in the framework of conductivity formalism. Magnetization of the samples are measured under the field cooled (EC) and zero field cooled (ZFC) modes in the temperature range from 5 K to 300 K applying a magnetic Field of 500 Oe. The FC and ZFC susceptibilities show that BE is a Van Vleck paramagnetic material with antiferromagnetic coupling at low temperature whereas BG is an anti-ferromagnetic system. The results are substantiated by the M-11 loops of the materials taken at 5 K in the ZFC mode. (C) 2014 Elsevier B.V. All rights reserved

High Throughput, Low Latency, Memory Optimized 64K Point FFT Architecture using Novel Radix-4 Butterfly Unit

In this paper we propose a fully parallel 64K point radix-4(4) FFT processor. The radix-4(4) parallel unrolled architecture uses a novel radix-4 butterfly unit which takes all four inputs in parallel and can selectively produce one out of the four outputs. The radix-4(4) block can take all 256 inputs in parallel and can use the select control signals to generate one out of the 256 outputs. The resultant 64K point FFT processor shows significant reduction in intermediate memory but with increased hardware complexity. Compared to the state-of-art implementation 5], our architecture shows reduced latency with comparable throughput and area. The 64K point FFT architecture was synthesized using a 130nm CMOS technology which resulted in a throughput of 1.4 GSPS and latency of 47.7 mu s with a maximum clock frequency of 350MHz. When compared to 5], the latency is reduced by 303 mu s with 50.8% reduction in area.

Biotechnological potential of plant-associated endophytic fungi:hope versus hype

The potential of endophytes, particularly endophytic fungi, capable of demonstrating desirable functional traits worth exploitation using red biotechnology is well established. However, these discoveries have not yet translated into industrial bioprocesses for commercial production of biopharmaceuticals using fungal endophytes. Here, we define the current challenges in transforming curiosity driven discoveries into industrial scale endophyte biotechnology. The possible practical, feasible, and sustainable strategies that can lead to harnessing fungal endophyte-mediated pharmaceutical products are discussed.

Evidence that TSC2 acts as a transcription factor and binds to and represses the promoter of Epiregulin

The TSC2 gene, mutated in patients with tuberous sclerosis complex (TSC), encodes a 200 kDa protein TSC2 (tuberin). The importance of TSC2 in the regulation of cell growth and proliferation is irrefutable. TSC2 in complex with TSC1 negatively regulates the mTOR complex 1 (mTORC1) via RHEB in the PI3K-AKT-mTOR pathway and in turn regulates cell proliferation. It shows nuclear as well as cytoplasmic localization. However, its nuclear function remains elusive. In order to identify the nuclear function of TSC2, a whole-genome expression profiling of TSC2 overexpressing cells was performed, and the results showed differential regulation of 266 genes. Interestingly, transcription was found to be the most populated functional category. EREG (Epiregulin), a member of the epidermal growth factor family, was found to be the most downregulated gene in the microarray analysis. Previous reports have documented elevated levels of EREG in TSC lesions, making its regulatory aspects intriguing. Using the luciferase reporter, ChIP and EMSA techniques, we show that TSC2 binds to the EREG promoter between -352 bp and -303 bp and negatively regulates its expression. This is the first evidence for the role of TSC2 as a transcription factor and of TSC2 binding to the promoter of any gene.

Electromagnetic Interference Shielding Materials Derived from Gelation of Multiwall Carbon Nanotubes in Polystyrene/Poly(methyl methacrylate) Blends

Blends of polystyrene (PS) and poly(methyl methacrylate) (PMMA) with different surface-functionalized multiwall carbon nanotubes (MWNTs) were prepared by solution blending to design materials with tunable EMI (electromagnetic interference) shielding. Different MWNTs like pristine, amine (similar to NH2), and carboxyl acid (similar to COOH) functionalized were incorporated in the polymer by solution blending. The specific interaction driven localization of MWNTs in the blend during annealing was monitored using contact mode AFM (atomic force microscopy) on thin films. Surface composition of the phase separated blends was further evaluated using X-ray photoelectron spectroscopy (XPS). The localization of MWNTs in a given phase in the bulk was further supported by selective dissolution experiments. Solution-casted PS/PMMA (50/50, wt/wt) blend exhibited a cocontinuous morphology on annealing for 30 min, whereas on longer annealing times it coarsened into matrix-droplet type of morphology. Interestingly, both pristine MWNTs and NH2-MWNTs resulted in interconnected structures of PMMA in PS matrix upon annealing, whereas COOH-MWNTs were localized in the PMMA droplets. Room-temperature electrical conductivity and electromagnetic shielding effectiveness (SE) were measured in a broad range of frequency. It was observed that both electrical conductivity and SE were strongly contingent on the type of surface functional groups on the MWNTs. The thermal conductivity of the blends was measured with laser flash technique at different temperatures. Interestingly, the SE for blends with pristine and NH2-MWNTs was >-24 dB at room temperature, which is commercially important, and with very marginal variation in thermal conductivity in the temperature range of 303-343 K. The gelation of MWNTs in the blends resulted in a higher SE than those obtained using the composites.

Digestive ripening and green synthesis of ultra-small (r < 2 nm) stable ZnO quantum dots

Given the recent reports pertaining to novel optical properties of ultra-small quantum dots (QDs) (r <2 nm), this nanomaterial is of relevance to both technology and science. However it is well known that in these size regimes most chalocogenide QD dispersions are unstable. Since applications often require use of QD dispersions (e.g. for deployment on a substrate), stabilizing these ultra-small particles is of practical relevance. In this work we demonstrate a facile, green, solution approach for synthesis of stable, ultra-small ZnO QDs having radius less than 2 nm. The particle size is calculated using Brits' equation and confirmed by transmission electron micrographs. ZnO QDs reported remain stable for > 120 days in ethanol (at similar to 298-303 K). We report digestive ripening (DR) in TEA capped ZnO QDs; this occurs rapidly over a short duration of 5 min. To explain this observation we propose a suitable mechanism based on the Lee's theory, which correlates the tendency of DR with the observed zeta potentials of the dispersed medium. To the best of our knowledge this is the (i) first report on DR in oxide QDs, as well as the first direct experimental verification of Lee's theory, and (ii) most rapid DR reported so far. The facile nature of the method presented here makes ultra-small ZnO readily accessible for fundamental exploration and technologically relevant applications. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Simultaneous measurements of thickness and temperature profile of the lubricant film at chip-tool interface during machining process using luminescent sensors

Simultaneous measurements of thickness and temperature profile of the lubricant film at chip-tool interface during machining have been studied in this experimental programme. Conventional techniques such as thermography can only provide temperature measurement under controlled environment in a laboratory and without the addition of lubricant. The present study builds on the capabilities of luminescent sensors in addition to direct image based observations of the chip-tool interface. A suite of experiments conducted using different types of sensors are reported in this paper, especially noteworthy are concomitant measures of thickness and temperature of the lubricant. (C) 2014 Elsevier Ltd.

Influence of initial degree of saturation on swell pressures of compacted Barmer bentonite specimens

Densely compacted bentonite or bentonite-sand mixture has been identified as suitable buffer in deep geological repositories as its exceptionally high swelling capacity enables tight contact between the waste canister and surrounding rock. The degree of saturation of the compacted bentonite buffer can increase upon ingress of groundwater from the surrounding rock mass or decrease from evaporation due to high temperature (50-210 degrees C) derived from the waste canister. Available studies indicate that the influence of initial moisture content or degree of saturation on the swell pressure or swell potential of compacted bentonites is unclear. Some studies suggest that initial degree of saturation has an influence, while others suggest that it does not have bearing on the swell pressure of compacted bentonites. This paper examines the influence of initial degree of saturation in montmorillonite voids (termed,S-r,S-MF) on swell pressure of compacted Barmer bentonite-sand mixtures (dry density range: 1.4-2 Mg/m(3)) from micro-structural considerations. The experimental results bring out that, constant dry density specimens that developed similar number of hydration layers upon wetting developed comparable swell pressures and were unaffected by variations in initial S-r,S-MF values. Comparatively, constant dry density specimens that developed dis-similar number of hydration layers upon wetting established different swell pressures and were responsive to variations in initial S-r,S-MF. (C) 2015 Elsevier Ltd. All rights reserved.

Changes in the expression of DNA double strand break repair genes in primordial follicles from immature and aged rats

Oocytes present at birth undergo a progressive process of apoptosis in humans and other mammals as they age. Accepted opinion is that no fresh oocytes are produced other than those present at the time of birth. Studies have shown that DNA repair genes in oocytes of mice and women decline with age, and lack of these genes show higher DNA breaks and increased oocyte death rates. In contrast to the ethical problems associated with monitoring the changes in DNA double-strand breaks in oocytes from young and old humans, it is relatively easy to carry out such a study using a rodent model. In this study, the mRNA levels of DNA repair genes are compared with protein products of some of the genes in the primordial follicles isolated from immature (18-20 days) and aged (400-450 days) female rats. Results revealed a significant decline in mRNA levels of BRAC1 (P < 0.01), RAD51 (P < 0.05), ERCC2 (P < 0.05), and H2AX (P < 0.01) of DNA repair genes and phospho-protein levels of BRAC1 (P < 0.01) and H2AX (P < 0.05) in primordial follicles of aged rats. Impaired DNA repair is confirmed as a mechanism of oocyte ageing. (C) 2014 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

Looking beyond parks: the conservation value of unprotected areas for hornbills in Arunachal Pradesh, Eastern Himalaya

The loss of tropical forests and associated biodiversity is a global concern. Conservation efforts in tropical countries such as India have mostly focused on state-administered protected areas despite the existence of vast tracts of forest outside these areas. We studied hornbills (Bucerotidae), an ecologically important vertebrate group and a flagship for tropical forest conservation, to assess the importance of forests outside protected areas in Arunachal Pradesh, north-east India. We conducted a state-wide survey to record encounters with hornbills in seven protected areas, six state-managed reserved forests and six community-managed unclassed forests. We estimated the density of hornbills in one protected area, four reserved forests and two unclassed forests in eastern Arunachal Pradesh. The state-wide survey showed that the mean rate of encounter of rufous-necked hornbills Aceros nipalensis was four times higher in protected areas than in reserved forests and 22 times higher in protected areas than in unclassed forests. The mean rate of encounter of wreathed hornbills Rhyticeros undulatus was twice as high in protected areas as in reserved forests and eight times higher in protected areas than in unclassed forests. The densities of rufous-necked hornbill were higher inside protected areas, whereas the densities of great hornbill Buceros bicornis and wreathed hornbill were similar inside and outside protected areas. Key informant surveys revealed possible extirpation of some hornbill species at sites in two protected areas and three unclassed forests. These results highlight a paradoxical situation where individual populations of hornbills are being lost even in some legally protected habitat, whereas they continue to persist over most of the landscape. Better protection within protected areas and creative community-based conservation efforts elsewhere are necessary to maintain hornbill populations in this biodiversity-rich region.

Continuous vapour adsorption cooling system with three adsorber beds

In this paper, the design of a new solar operated adsorption cooling system with two identical small and one large adsorber beds, which is capable of producing cold continuously, has been proposed. In this system, cold energy is stored in the form of refrigerant in a separate refrigerant storage tank at ambient temperature. Silica gel water is used as a working pair and system is driven by solar energy. The operating principle is described in details and its thermodynamic transient analysis is presented. Effect of COP and SCE for different adsorbent mass and adsorption/desorption time of smaller beds are discussed. Recommended mass and number of cycles of operation for smaller beds to attain continuous cooling with average COP and SCE of 0.63 and 337.5 kJ/kg, respectively are also discussed, at a generation, condenser and evaporator temperatures of 368 K, 303 K and 283 K, respectively. (C) 2015 Elsevier Ltd. All rights reserved.

Conformational Stability and Intramolecular Hydrogen Bonding in 1,2-Ethanediol and 1,4-Butanediol

The gas-phase infrared spectra of 1,2-ED and 1,4-BD have been, recorded at three different temperatures using a multipass gas cell of 6 m optical path length. DFT calculation has also been carried out using 6-311++G** and aug-cc-pVDZ basis sets to look for the existence of intramolecular hydrogen bonding, in them from the red shift and infrared absorption intensity enhancement of the bonded O-H band compared to that of the free O-H hand. Equilibrium population analysis With 10 conformers of 1,2-ED and 1,4-BD at experimental temperatures were-carried out for the reconstruction of the Observed vibrational spectra at that temperature,using standard statistical relationships. The most abundant conformer at experimental temperatures, was identified. In 1,2-ED a red shift of 45 cm(-1) in the intramolecularly interacting O-H stretching vibrational band position and no significant intensity enhancement compared to that of-the free O-H have been observed. On the contrary, in one of the hydrogen bonded conformers of 1,4-BD, a 124 cm(-1) red shift in the O-H stretching frequency and 8.5 times-intensity enhancement for the ``bonded'' O-H compared to that of the ``free'' O-H is seen. On the basis of this comparative study, we have concluded that strong intramolecular hydrogen bonding exists in 1,4-BD. But there appears, to be weak intramolecular hydrogen bonding in 1,2-ED at temperatures of 303, 313, and 323 Km the gas phase We have found that most stable hydrogen-bonded conformers of 1,4-BD are less populated than some of the non-hydrogen-bonded conformers. Even for the 1,4-BD, the relative population of the g'GG'Gt conformer, which has a strong intramolecular,hydrogen bond, is less than what is predicted. Perhaps the intramolecular hydrogen bond plays a less Significant role in the relative stability,of the various Conformers than what has been predicted from calculations and prevails in the literature.

Nonlinear Optical Properties and Temperature-Dependent UV-Vis Absorption and Photoluminescence Emission in 2D Hexagonal Boron Nitride Nanosheets

Recently, a lot of interest has been centred on the optical properties of hexagonal boron nitride (h-BN), which has a similar lattice structure to graphene. Interestingly, h-BN has a wide bandgap and is biocompatible, so it has potential applications in multiphoton bioimaging, if it can exhibit large nonlinear optical (NLO) properties. However, extensive investigation into the NLO properties of h-BN have not been done so far. Here, NLO properties of 2D h-BN nanosheets (BNNS) are reported for the first time, using 1064-nm NIR laser radiation with a pulse duration of 10 ns using the Z-scan technique. The reverse saturable absorption occurs in aqueous colloidal solutions of BNNS with a very large two-photon absorption cross section (sigma(2PA)) of approximate to 57 x 10(-46) cm(4) s(-1) photon(-1). Also, by using UV-Vis absorption spectroscopy, the temperature coefficient of the bandgap (dE(g)/dT) of BNNS is determined to be 5.9 meV K-1. Further defect-induced photoluminescence emission in the UV region is obtained in the 283-303 K temperature range, under excitations of different wavelengths. The present report of large sigma(2PA) combined with stability and biocompatibility could open up new possibilities for the application of BNNS as a potential optical material for multiphoton bioimaging and advanced photonic devices.

Drift parameters optimization of a TPC polarimeter: a simulation study

Time Projection Chamber (TPC) based X-ray polarimeters using Gas Electron Multiplier (GEM) are currently being developed to make sensitive measurement of polarization in 2-10 keV energy range. The emission direction of the photoelectron ejected via photoelectric effect carries the information of the polarization of the incident X-ray photon. Performance of a gas based polarimeter is affected by the operating drift parameters such as gas pressure, drift field and drift-gap. We present simulation studies carried out in order to understand the effect of these operating parameters on the modulation factor of a TPC polarimeter. Models of Garfield are used to study photoelectron interaction in gas and drift of electron cloud towards GEM. Our study is aimed at achieving higher modulation factors by optimizing drift parameters. Study has shown that Ne/DME (50/50) at lower pressure and drift field can lead to desired performance of a TPC polarimeter.