Reverse Micelle Based Synthesis of Microporous Materials in Microgravity

Formation of zincophosphates from zinc and phosphate containing reverse micelles (water droplets in hexane) has been examined. The frameworks formed resemble that made by conventional hydrothermal synthesis. Dynamics of crystal growth are however quite different, and form the main focus of this study. In particular, the formation of zincophosphate with the sodalite framework was examined in detail. The intramicellar pH was found to have a strong influence on crystal growth. Crystals with a cubic morphology were formed directly from the micelles, without an apparent intermediate amorphous phase over a period of four days by a layer-bylayer growth at the intramicellar pH of 7.6. At a pH of 6.8, an amorphous precipitate rapidly sediments in hours. Sodalite was eventually formed from this settled phase via surface diffusion and reconstruction within four days. With a rotating cell, it was possible to minimize sedimentation and crystals were found to grow epitaxially from the spherical, amorphous particles. Intermediate pH's of 7.2 led to formation of aggregated sodalite crystals prior to settling, again without any indication of an intermediate amorphous phase. These diverse pathways were possible due to changes in intramicellar supersaturation conditions by minor changes in pH. In contrast, conventional syntheses in this pH range all proceeded by similar crystallization pathways through an amorphous gel. This study establishes that synthesis of microporous frameworks is not only possible in reverse micellar systems, but they also allow examination of possible crystallization pathways

Study of Calcination-Carbonation of Calcium Carbonate in Different Fluidizing Mediums for Chemical Looping Gasification in Circulating Fluidized Beds

Chemical looping gasification (CLG) of biomass in a circulating fluidized bed is an excellent option for production of separate streams of hydrogen rich and carbon dioxide rich gases. This process uses H2O (steam) instead of air or oxygen for gasification, and thereby produces high value nitrogen free product gas. An important feature of this process is in-process removal of carbon dioxide from the reaction site by CaO. This allows the reaction to move towards higher yield of hydrogen. Circulating fluidized bed (CFB) provides an ideal reactor configuration for such a looping reaction. A CFB based CLG unit operates somewhat similar to the FCC reactor except that the bubbling bed in the loopseal serves as the gasifier where calcined limestone absorbs carbon dioxide forming calcium carbonate. The riser works as the regenerator of CaCO3, the CO2 sorbent. Thus, the sorbent particles move back and forth between the riser calciner and loopseal carbonizer. To study this process closely and to determine how well the sorbent retains its reactivity through such a cyclical process, an experiment was carried out in a Quartz wool matrix reactor (QWM), which closely simulates the highly expanded ambience of a fast-fluidized bed. An empirical relation was developed for the conversion of calcium carbonate (CaCO3) as a function of temperature and residence time. A simple reaction kinetic model for calcination in presence of N2, CO2 and H2O has been developed and compared. Loss in effectiveness of the sorbent has been studied and another empirical relation was developed for the estimation of extent of carbonation with the number of cycle

CO-INFECTION OF BRUCELLA AND DENGUE VIRUS

Objective: Brucellosis is an important zoonotic infection having a worldwide distribution. In South East Asian developing countries like India, brucellosis is yet well-known but often neglected disease. Although dengue fever has a global distribution, South East Asian region together with the Western Pacific region represents 75% of the current global disease burden. Frequent dengue fever outbreaks have been encountered in different parts of India. Both brucellosis and dengue fever may present with many nonspecific symptoms. This study was designed to identify the trend of their co-infection.Methods: The study was carried out from February 2015 to July 2016 in Eastern India. Blood samples collected from clinically suspected dengue fever cases were confirmed serologically by dengue specific NS1, IgM, and IgG capture ELISA methods. The confirmed dengue samples were further subjected to Brucella specific serological and molecular investigations.Results: Out of 37 serologically confirmed dengue cases, 8 (21.6%) showed co-infection of brucellosis and dengue fever. Female predominance was observed among the co-infection cases. Most of these cases belonged to the age group 21-40 years and resided in and around Kolkata.Conclusion: This study portrays the simultaneous acquisition of these two pathogens in a few patients. Co-infection of these two pathogens, while feasible, has not been accounted previously in this part of India. Thus, this report highlights the significance of studying the possibility of occurrence of dual infection of these two diseases and its outcome in patients with febrile illness thereby providing future scope of preventing case fatalitiesKeywords: Brucellosis, Dengue, Co-infection, ELISA, Polymerase chain reaction

Structure and Vibrational Spectra of Mononitrated Benzo [a] Pyrenes.

The molecules benzo[a]pyrene (BaP) and 1-, 3-, and 6-nitrobenzo[a]pyrene (1-NBaP, 3-NBaP, 6-NBaP) are currently of significant interest due to their presence in respirable combustion exhaust particulates and their mutagenic and carcinogenic properties. Structure−function correlations as well as spectroscopic signatures for trace analysis are necessary for these benzo[a]pyrene derivatives. In this paper, detailed infrared and Raman spectroscopic data of BaP and its three mononitrated isomers are provided for the first time. By utilizing density functional theory (DFT, B3LYP method with 6-311+G** basis set), the molecular geometries and the vibrational spectra are calculated. Good agreement is noted between the calculated and experimental geometry for BaP, and predictions of the vibrational data for all compounds are within ∼5 cm-1 of the experimental data. Normal mode assignments are proposed with particular emphasis on the nitro group vibrations. The geometrical distortions of the BaP structure upon nitro group substitution and correlations between structural parameters and vibrational data as well as structure−function relationships related to the mutagenicity of this important class of polycyclic aromatic hydrocarbons are discussed

Mixed Ionic and Electronic Conduction in Li_3PO_4 Electrolyte for a CO_2 Gas Sensor

An electrochemical CO_2 gas sensor using Li_2CO_3 and Li_2TiO_3+TiO_2 as sensing and reference electrodes, respectively, and Li_3PO_4 as the electrolyte is the subject of this paper. The sensor response to CO_2 gas showed a systematic deviation from the prediction of the Nernst equation at low pCO_2. Based on the electromotive force (emf) measurement, the transference numbers of Li_3PO_4, a lithium-ion conductor, were estimated for different pCO_2 values, and the conduction domain boundary for Li_3PO_4 separating n-type electronic conduction from ionic conduction was constructed. The conduction domain predicts that change in the Li activity in the sensing side of the cell drives the Li_3PO_4 electrolyte to a mixed (n-type electronic and ionic) conduction region at low pCO_2. Hebb-Wagner dc polarization measurements also indicate n-type electronic conduction in Li_3PO_4 with a mixture of Li_2CO_3 and gold as a reversible electrode. The transference numbers obtained from both the emf measurement and the Hebb-Wagner polarization measurements demonstrate that the origin of the non-Nernstian behavior of the CO_2 sensor is due to the lithium mass transport from the Li_2CO_3-sensing electrode to the Li_3PO_4 electrolyte, resulting in nonstoichiometry of Li_3PO_4 at temperatures above 500°C

COMPARISON OF SEROLOGICAL TESTS AND PCR FOR DIAGNOSIS OF HUMAN BRUCELLOSIS SUFFERING FROM FEVER

Objective: Brucellosis is an important zoonotic disease throughout the globe and other developing countries. The present study was aimed to compare results of different serological tests and PCR for diagnosis of brucellosis in patients sufferings from fever in Kolkata and in adjoining districts.Methods: A total of 2088 serum samples were collected from the patients suffering from fever from January, 2013 to September, 2015. The samples were tested by serological tests STAT, RBPT, ELISA(IgM,IgG) and Brucella genus specific PCR. Results: The study revealed decreasing positive results by STAT (18.43%, N=385), RBPT (12.59%, N=263), IgM ELISA (7.71%, N=161), PCR (4.21%, N=88) and IgG ELISA (1.43%, N=30). When serological tests were compared with PCR, it was found that both STAT and PCR were positive in 84 samples( 4.02%), both RBPT and PCR were positive in 65 samples(3.11%), both IgM and PCR were positive in 51 samples(2.44%) and both IgG and PCR were positive in 9 samples(0.43%). Conclusion: In this cross sectional study in a zonal population of India it was found that STAT was the most sensitive test for diagnosis of brucellosis followed by RBPT when compared to PCR test results. Four STAT negative samples showed positive results in PCR, which were positive by RBPT test. This indicates that if we combine STAT and RBPT for diagnosis of brucellosis then both sensitivity and specificity of the combined test will increase.Â

Novel optically active lead-free relaxor ferroelectric (Ba0.6Bi0.2Li0.2)TiO3

We discovered a near room temperature lead-free relaxor-ferroelectric (Ba0.6Bi0.2Li0.2)TiO3 (BBLT) having A-site compositional disordered ABO3 perovskite structure. Microstructure-property relations revealed that the chemical inhomogeneities and development of local polar nano regions (PNRs) are responsible for dielectric dispersion as a function of probe frequencies and temperatures. Rietveld analysis indicates mixed crystal structure with 80% tetragonal structure (space group P4mm) and 20% orthorhombic structure (space group Amm2) which is confirmed by the high resolution transmission electron diffraction pattern. Dielectric constant and tangent loss dispersion with and without illumination of light obey nonlinear Vogel-Fulture relation. It shows slim polarization-hysteresis (P-E) loops and excellent displacement coefficients (d33 ~ 233 pm/V) near room temperature, which gradually diminish near the maximum dielectric dispersion temperature (Tm). The underlying physics for light-sensitive dielectric dispersion was probed by X-ray photon spectroscopy (XPS) which strongly suggests that mixed valence of bismuth ions, especially Bi5+ ions, are responsible for most of the optically active centers. Ultraviolet photoemission measurements showed most of the Ti ions are in 4+ states and sit at the centers of the TiO6 octahedra, which along with asymmetric hybridization between O 2p and Bi 6s orbitals appears to be the main driving force for net polarization. This BBLT material may open a new path for environmental friendly lead-free relaxor-ferroelectric research.Comment: 23 pages, 5 figure

Self organized criticality of magnetic avalanches in disordered ferrimagnetic material

We observe multiple step-like jumps in a Dy-Fe-Ga-based ferrimagnetic alloy in its magnetic hysteresis curve at 2 K. The observed jumps have a stochastic character with respect to their magnitude and the critical field of occurrence, and the jumps do not show any temporal effect. The jump size distribution follows a power law variation indicating the scale invariance nature of the jumps. We have invoked a simple two-dimensional random bond Ising-type spin system to model the dynamics. Our computational work can qualitatively reproduce the jumps and their scale invariant character. It also elucidates that the flipping of antiferromagnetically coupled Dy and Fe clusters is responsible for the observed discrete avalanche-like features in the hysteresis loop. These characteristics indicate that the present phenomenon can be well described within the realm of self-organized criticalityComment: 12 pages, 13 figure

A Review on the Degradation of Ionic and Non Ionic Surfactants in Water

The ability to respond to changing consumer and industrial wastes is critical for water treatment. Surfactants are of importance because of their increasing prevalence in home and industrial settings, as well as the challenges they provide to standard treatment. Surface active agents (SAAs) are chemical compounds that are discharged into the environment. They may have a deleterious impact on ecosystem biotic components. They also produce an increase in the aqueous phase solubility of organic contaminants. The destiny of SAAs in the environment is currently uncertain. Recognizing this issue will help to safeguard live species and maintain the quality and balance of a diverse ecosystem.This critical evaluation considers studies from several technical disciplines to offer an up-to-date summary of the environmental effects of surfactants. A variety of technologies are discussed, as well as their drawbacks and potential solutions

A Simple Analytical Model of a GaN MODFET to Study its DC and RF Performance

395-400This work presents a theoretical study of a GaN MODFET considering accurate velocity field relation of GaN for a wide range of electric field. The analytical expression of different DC parameters such as drain current, mutual conductance and drain conductance of the device has been derived and their variation over different field regions has been investigated. This work has also been extended to study the RF parameters like cut-off frequency and maximum operating frequency of the device. The threshold voltage of the device is also derived and studied in terms of the thickness of the doped AlGaN layer and mole fraction of AlGaN. The mathematical model presented here is calibrated with the experimentally available results reported earlier and a good agreement has been observed