Insight into morphology changes of nanoparticle laden droplets in acoustic field

Hollow structures with unique morphologies form due to particle agglomeration in acoustically levitated nanofluid functional droplets when subjected to external heating. The final diameter of the structure depends only on the ratio of agglomeration to evaporation time scales for various nanoparticle laden droplets, and not on the type of the suspended particles. These time scales depend only on nanoparticle concentration. This valuable information may be exploited to form microstructures with desired properties from ceramic compounds. Phase diagrams for alumina and silica droplets indicate the transition from a bowl to ring structure depending on concentration.

Surface morphology, optical properties and conductivity changes of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) by using additives

The optical properties and electrical conductivity of highly conducting poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonate) (PSS) are reported as a function of the processing additive conditions. The addition of dimethyl sulfoxide (DMSO) increases the conductivity and modifies the dielectric response as observed from the ellipsometric studies. Also the surface roughness and morphology change with the composition of PEDOT: PSS: DMSO and film deposition conditions. The real part of the dielectric function becomes negative in highly conducting samples, indicating the presence of delocalized charge carriers. The real and imaginary parts of the refractive index were determined as a function of wavelength. The results are consistent with the increase in conductivity upon the addition of DMSO.

Sea-level changes and its impact on coastal archaeological monuments: seven pagodas of Mahabalipuram, a case study

The name `Seven Pagodas' has served as a nickname for the south Indian port of Mahabalipuram since the early European explorers used it as landmark for navigation as they could see summits of seven temples from the sea. There are many theories concerning the name Seven Pagodas. The present study has compared coastline and adjacent seven monuments illustrated in a 17th century Portolan Chart (maritime map) with recent remote sensing data. This analysis throws new light on the name ``Seven Pagodas'' for the city. This study has used DEM of the site to simulate the coastline which is similar to the one depicted in the old portolan chart. Through this, the then sea level and corresponding flooding extent according to topography of the area and their effect on monuments could be analyzed. Most importantly this work has in the process identified possibly the seven monuments that constituted the name Seven Pagodas and this provides an alternative explanation to one of the mysteries of history. This work has demonstrated unique method of studying coastal archaeological sites. As large numbers of heritage sites around the world are on coastlines, this methodology has potential to be very useful for coastal heritage preservation and management.

Potential ultrastructural changes in rat epididymal cell types induced by Boswellia papyrifera and Boswellia carterii incense

Boswellia papyrifera and Boswellia carterii, known as Arabian incense, diffuses smoke, contaminating the air, which adversely affects human health. Therefore, this study was designed to ascertain the effect of these plants on histopathological and ultrastructure changes in cauda epididymis of Albino rats. Animals were exposed to 4 g/kg body weight of B. papyrifera and B. carterii daily for 120 days along with suitable controls. Our study indicates a significant reduction in epithelial heights. Cells showed signs of degeneration. The ultrastructural study revealed that the cauda epididymis was affected, including its cell types. Furthermore, a decrease in the size of mitochondria, Golgi complex, and both ERs was observed. In all treated groups, plasma fructose decreased considerably, indicating the sign of reduced energy, vital for motility and other sperm functions. The results of this study suggest that these plants systematically affect cauda epididymal cell types and its lumen through its potential toxicity. (C) 2013 Published by Elsevier Masson SAS on behalf of Academie des sciences.

Solvent-induced changes on the polarity of the triplet excited state of 2-chlorothioxanthone: From time-resolved absorption and resonance Raman spectroscopies

Solvent polarity has been known to influence the triplet state structure and reactivity. Here, we present our experimental and theoretical study on the effect of solvent on the lowest triplet excited state structure of 2-chlorothioxanthone (CTX). Time-resolved absorption (TA) spectroscopy has been employed to understand the triplet state electronic structure; whereas solvent-induced structural changes have been studied using time-resolved resonance Raman (TR3) spectroscopy. Both the DFT and TD-DFT calculations have been performed in the solution phase employing self-consistent reaction field implicit solvation model to support the experimental data. It has been observed that CO stretching frequencies of the excited triplet state are sensitive to the solvent polarity and increase with the increase in the solvent polarity. Both TA and TR3 studies reveal that specific solvent effect (H-bonding) is more pronounced in comparison to the nonspecific solvent effect. (C) 2013 Elsevier B.V. All rights reserved.

Observed changes in Himalayan glaciers

In the Himalaya, large areas are covered by glaciers and seasonal snow. They are an important source of water for the Himalayan rivers. In this article, observed changes in glacial extent and mass balance have been discussed. Various studies suggest that most of the Himalayan glaciers are retreating though the rate of retreat varies from glacier to glacier, ranging from a few meters to almost 61 m/year, depending upon the terrain and meteorological parameters. In addition, mapping of almost 11,000 out of 40,000 sq. km of glaciated area, distributed in all major climatic zones of the Himalaya, suggests an almost 13% loss in area in the last 4-5 decades. The glacier mass balance observations and estimates made using methods like field, AAR, ELA and geodetic measurements, suggest a significant increase in mass wastage of Himalayan glaciers in the last 3-4 decades. In the last four decades loss in glacial ice has been estimated at 19 +/- 7 m. This suggests loss of 443 +/- 136 Gt of glacial mass out of a total 3600-4400 Gt of glacial stored water in the Indian Himalaya. This study has also shown that mean loss in glacier mass in the Indian Himalaya is accelerated from -9 +/- 4 to -20 +/- 4 Gt/year between the periods 1975-85 and 2000-2010. The estimate of glacial stored water in the Indian Himalaya is based on glacier inventory on a 1 : 250,000 scale and scaling methods; therefore, we assume uncertainties to be large.

Glacial mass balance changes in the Karakoram and Himalaya based on CMIP5 multi-model climate projections

The impact of future climate change on the glaciers in the Karakoram and Himalaya (KH) is investigated using CMIP5 multi-model temperature and precipitation projections, and a relationship between glacial accumulation-area ratio and mass balance developed for the region based on the last 30 to 40 years of observational data. We estimate that the current glacial mass balance (year 2000) for the entire KH region is -6.6 +/- 1 Gta(-1), which decreases about sixfold to -35 +/- 2 Gta(-1) by the 2080s under the high emission scenario of RCP8.5. However, under the low emission scenario of RCP2.6 the glacial mass loss only doubles to -12 +/- 2 Gta(-1) by the 2080s. We also find that 10.6 and 27 % of the glaciers could face `eventual disappearance' by the end of the century under RCP2.6 and RCP8.5 respectively, underscoring the threat to water resources under high emission scenarios.

Cybernetic modeling of adaptive prediction of environmental changes by microorganisms

Microorganisms exhibit varied regulatory strategies such as direct regulation, symmetric anticipatory regulation, asymmetric anticipatory regulation, etc. Current mathematical modeling frameworks for the growth of microorganisms either do not incorporate regulation or assume that the microorganisms utilize the direct regulation strategy. In the present study, we extend the cybernetic modeling framework to account for asymmetric anticipatory regulation strategy. The extended model accurately captures various experimental observations. We use the developed model to explore the fitness advantage provided by the asymmetric anticipatory regulation strategy and observe that the optimal extent of asymmetric regulation depends on the selective pressure that the microorganisms experience. We also explore the importance of timing the response in anticipatory regulation and find that there is an optimal time, dependent on the extent of asymmetric regulation, at which microorganisms should respond anticipatorily to maximize their fitness. We then discuss the advantages offered by the cybernetic modeling framework over other modeling frameworks in modeling the asymmetric anticipatory regulation strategy. (C) 2013 Published by Elsevier Inc.

Ultrastructural and hormonal changes in rat cauda epididymal spermatozoa induced by Boswellia papyrifera and Boswellia carterii

Boswellia papyrifera and Boswellia carterii diffuses smoke polluting air that adversely affects indoor environment that certainly harm human health. Therefore, this study aims at ascertaining the effect of these plants on gonadal hormones and molecular changes in rat spermatozoa. The animals were exposed to 4 g/kg body weight of B. papyrifera and B. carterii daily for 120 days along with suitable controls. Significant decreases in FSH, LH and testosterone levels were evidenced, along with a reduction of protein, sialic acid, and carnitine levels. In sperm physiology, sperm count, motility, speed decrease, whereas sperm anomalies increase. TEM observation indicates morphological changes in plasma and acrosomal membranes, cytoplasmic droplet in the tail region, vacuolated, and disorganization of the mitochondrial sheath. These findings demonstrate that B. papyrifera and B. carterii smoke affects the process of sperm formation and maturation, which indicates the detrimental effects of these plants on the reproductive system. (c) 2014 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.d

Do stable isotopes in carbonate cement of Mio-Pleistocene Himalayan sediments record paleoecological and paleoclimatic changes?

Non-pedogenic carbonates, such as carbonate cement and nodules in the sandstones, are quite common in the terrestrial geological record. Unlike pedogenic carbonates, their stable isotope ratios lack investigations for paleo-climatic reconstructions. The present investigation therefore, explores the possibility of use of stable isotope studies of non-pedogenic carbonates from the Mb-Pleistocene Siwalik Group of sediments exposed in the Ramnagar sub-basin of the NW Himalaya. Petrographic studies reveal the dominance of micrite fabric in carbonate nodules both of pedogenic and non-pedogenic samples irrespective of specific stratigraphic unit However, calcite as cement in the sandstones shows the dominance of micrite fabric in the younger in age sediments. Seventy-two non-pedogenic carbonate samples from the carbonate nodules and cement in the Siwalik sandstones, ranging in age between similar to 1 Ma and 12.2 Ma, were analyzed for delta C-13 and delta O-18 values. The delta C-13 values vary from -24.77 parts per thousand to -1.1 parts per thousand and delta O-18 values vary from -15.34 parts per thousand to -7.81 parts per thousand. Pedogenic and non-pedogenic carbonates ranging in age between similar to 1 Ma and 6 Ma have largely similar delta C-13 values and the range of delta C-13 values indicate the dominance of C-4 type of vegetation. However, unlike pedogenic carbonates which showed the dominance of C-3 type of vegetation pre- 7 Ma on the basis of delta C-13 -depleted isotopic values (Singh et al., 2011), delta C-13 values are largely enriched in the corresponding aged non-pedogenic carbonates revealing no information on specific type of vegetation. Likewise, paleoprecipitational reconstructions from delta O-18 values in pedogenic carbonates showed a progressive increase in aridity from similar to 12 Ma to recent excluding short term increases in rainfall/monsoon intensity at around 10 Ma, 5 Ma, and 1.8 Ma (Singh et al., 2012). On the contrary, such reconstructions are not possible from the delta O-18 values of non-pedogenic carbonates and indeed the delta O-18 values of non-pedogenic carbonates are largely depleted to as much as 6 parts per thousand from the corresponding pedogenic carbonates. Such differences in delta C-13 and delta O-18 values of non-pedogenic carbonates from pedogenic carbonates are primarily due to the dependence of the former on groundwater conditions responsible for precipitating carbonate. Further, a comparison of isotopic values between non-pedogenic and pedogenic carbonates can be interpreted that post-6 Ma and pre-6 Ma non-pedogenic carbonates were largely formed by shallow and deep groundwater conditions respectively. The result of these investigative studies therefore, suggests that the stable delta C-13 and delta O-18 values of non-pedogenic carbonates, unlike the pedogenic carbonates and irrespective of nature of calcite fabric, showed their little importance in paleoclimatic and paleoecological reconstructions. (C) 2014 Elsevier B.V. All rights reserved.

Reversible and irreversible pH induced conformational changes in self-assembled weak polyelectrolyte multilayers probed using etched fiber Bragg grating sensors

Polyelectrolytes are charged polymer species which electrostatically adsorb onto surfaces in a layer by layer fashion leading to the sequential assembly of multilayer structures. It is known that the morphology of weak polyelectrolyte structures is strongly influenced by environmental variables such as pH. We created a weak polyelectrolyte multilayer structure (similar to 100 nm thick) of cationic polymer poly-allylamine hydrochloride (PAH) and an anionic polymer poly-acrylic acid (PAA) on an etched clad fiber Bragg grating (EFBG) to study the pH induced conformational transitions in the polymer multilayers brought about by the variation in charge density of weak polyelectrolyte groups as a function of pH. The conformational changes of the polyelectrolyte multilayer structure lead to changes in optical density of the adsorbed film which reflects in the shift of the Bragg wavelength from the EFBG. Using the EFBG system we were able to probe reversible and irreversible pH induced transitions in the PAH/PAA weak polyelectrolyte system. (C) 2014 Elsevier B.V. All rights reserved.

Sign changes of Fourier coefficients of Hilbert modular forms

Sign changes of Fourier coefficients of various modular forms have been studied. In this paper, we analyze some sign change properties of Fourier coefficients of Hilbert modular forms, under the assumption that all the coefficients are real. The quantitative results on the number of sign changes in short intervals are also discussed. (C) 2014 Elsevier Inc. All rights reserved.

Hydrophobic hydration driven self-assembly of curcumin in water: Similarities to nucleation and growth under large metastability, and an analysis of water dynamics at heterogeneous surfaces

As the beneficial effects of curcumin have often been reported to be limited to its small concentrations, we have undertaken a study to find the aggregation properties of curcumin in water by varying the number of monomers. Our molecular dynamics simulation results show that the equilibrated structure is always an aggregated state with remarkable structural rearrangements as we vary the number of curcumin monomers from 4 to 16 monomers. We find that the curcumin monomers form clusters in a very definite pattern where they tend to aggregate both in parallel and anti-parallel orientation of the phenyl rings, often seen in the formation of beta-sheet in proteins. A considerable enhancement in the population of parallel alignments is observed with increasing the system size from 12 to 16 curcumin monomers. Due to the prevalence of such parallel alignment for large system size, a more closely packed cluster is formed with maximum number of hydrophobic contacts. We also follow the pathway of cluster growth, in particular the transition from the initial segregated to the final aggregated state. We find the existence of a metastable structural intermediate involving a number of intermediate-sized clusters dispersed in the solution. We have constructed a free energy landscape of aggregation where the metatsable state has been identified. The course of aggregation bears similarity to nucleation and growth in highly metastable state. The final aggregated form remains stable with the total exclusion of water from its sequestered hydrophobic core. We also investigate water structure near the cluster surface along with their orientation. We find that water molecules form a distorted tetrahedral geometry in the 1st solvation layer of the cluster, interacting rather strongly with the hydrophilic groups at the surface of the curcumin. The dynamics of such quasi-bound water molecules near the surface of curcumin cluster is considerably slower than the bulk signifying a restricted motion as often found in protein hydration layer. (C) 2014 AIP Publishing LLC.

Tin-Incorporation Induced Changes in the Microstructural, Optical, and Electrical Behavior of Tungsten Oxide Nanocrystalline Thin Films Grown Via Spray Pyrolysis

Undoped and Sn-doped WO3 thin films were grown on cleaned glass substrates by chemical spray pyrolysis, using ammonium tungstate (NH4)(2)WO4 as the host precursor and tin chloride (SnCl4 center dot 5H(2)O) as the source of dopant. The XRD spectra confirm the monoclinic structure with a sharp narrow peak along (200) direction along with other peaks of low relative intensities for all the samples. On Sn doping, the films exhibit reduced crystallinity relative to the undoped film. The standard deviation for relative peak intensity with dopant concentration shows enhancement in heterogeneous nucleation growth. As evident from SEM images, on Sn doping, appearance of island-like structure (i.e., cluster of primary crystallites at few places) takes place. The transmittance has been found to decrease in all the Sn-doped films. The optical band gap has been calculated for both direct and indirect transitions. On Sn doping, the direct band gap shows a red shift and becomes 2.89 eV at 2 at.% doping. Two distinct peaks, one blue emission at 408 nm and other green emission at 533 nm, have been found in the PL spectra. Electrical conductivity has been found to increase with Sn doping.

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.