Effect of Network Structure on Free Volume and Gas Transport Properties of Thiol-Ene and Epoxy-Amine Networks

Network parameters such as cross-link density or intermolecular interactions were used as effective parameters to control polymer chain packing or free volume and thereby control the mass transport properties of networks. A series of polyethylene glycol (PEG) based thiol-ene elastomeric networks having a broad range of molecular weight between cross-links, Mc, (inverse of cross-link density) was prepared. The specific volume of the networks was studied as a function of temperature and pressure using high pressure dilatometry, and the obtained PVT data was fit using Simha-Somcynsky equation of state (S-S eos) analysis. Fractional free volume, quantified through S-S eos analysis, changed linearly as a function of cross-link density of the networks proving that the system obeyed Fox and Loshaek model. Average free volume hole size, h\u3e, of the networks was directly probed using positron annihilation lifetime spectroscopy (PALS). h\u3e of the networks also changed linearly as a function of cross-link density. Typically, in traditional elastomers, changing cross-link density also causes simultaneous changes in chemical nature or polarity of the system, therefore those systems deviate from Fox and Loshaek model. Internal pressure Pi of the networks, calculated from PVT data, showed similar values for all networks, and the same was the case for storage permittivity values obtained from dielectric spectroscopy analysis. This proved that the chemical nature of the networks was unaffected and cross-link density was the only parameter controlling the free volume of the networks. Gas diffusivity of the networks obeyed Cohen Turnbull model, and thus the experimental gas diffusivity trends were modeled as a function of molecular weight between cross-links of the networks. The effect of intermolecular (repulsive) interactions on free volume and gas transport was studied in a series of perfluorinated thiol-ene elastomers. Perfluorinated thiol-ene elastomers were prepared via 2-step synthesis. In the first step, a four-functional thiol was converted into a three functional thiol containing a perfluorinated dangling moiety via Thio Michael addition reaction with a perfluorinated acrylate. The modified thiol monomer was then reacted with triene to obtain perfluorinated thiol-ene networks. Fluorine content was varied by changing the length of perfluorinated moiety used in Thio Michael addition and this enabled the synthesis of a series of perfluorinated networks containing perfluorinated dangling moieties of different lengths. Fast reaction kinetics of thiol-ene chemistry prevented the phase separation of perfluorinated moieties and locked-in the thermodynamically frustrated perfluorinated moieties within the thiol-ene scaffold. The repulsive interactions between highly non-polar perfluorinated moieties and polar thiol-ene backbone created huge free volume pockets in the network. For the biggest perfluorinated dangling moiety used in this study, h\u3e increased by four times in comparison to an unmodified network. The gas transport properties showed a significant improvement as a function of the length of the dangling moiety. But gas diffusivity of the networks did not obey Cohen Turnbull model. The deviation was explained by the static nature of free volume pockets around perfluorinated moieties, and percolation of free volume pockets as the sizes of free volume cavities increased. The 2-step synthetic approach was taken a step further to prepare a series of hybrid thiol-ene elastomers containing varying concentrations of polar PEG moieties and non-polar perfluorinated moieties. The effect of PEG and perfluorinated concentrations (or attractive and repulsive interactions) on chain packing was studied. PEG moieties improved CO2 gas permeability and selectivity because of the Lewis acid-base type interactions between PEG and CO2. In the final chapter, the effect of moisture sorption on free volume, oxygen, and water vapor transport was studied on five different epoxy-amine networks having Tgs in the range between -11 °C to 227 °C. Water sorption did not show any effect on h\u3e of elastomeric networks. Whereas, glassy networks showed a V-shaped trend when h\u3e was plotted as a function of relative humidity or water content. The decrease in h\u3e was due to water molecules filling free volume holes. Increasing water concentration in the networks beyond 75% relative humidity (RH) resulted in swelling of the networks and thereby h\u3e increase. Effect of water sorption on oxygen permeability of the glassy networks also showed a similar V-shaped trend, but the mechanism was more complex as water sorption affected both oxygen diffusivity and solubility. Water vapor permeability of the glassy networks was unaffected until 75% RH. Beyond 75% RH, free volume increase due to swelling resulted in water vapor permeability increase

Results from the centers for disease control and prevention's predict the 2013-2014 Influenza Season Challenge

Background: Early insights into the timing of the start, peak, and intensity of the influenza season could be useful in planning influenza prevention and control activities. To encourage development and innovation in influenza forecasting, the Centers for Disease Control and Prevention (CDC) organized a challenge to predict the 2013-14 Unites States influenza season. Methods: Challenge contestants were asked to forecast the start, peak, and intensity of the 2013-2014 influenza season at the national level and at any or all Health and Human Services (HHS) region level(s). The challenge ran from December 1, 2013-March 27, 2014; contestants were required to submit 9 biweekly forecasts at the national level to be eligible. The selection of the winner was based on expert evaluation of the methodology used to make the prediction and the accuracy of the prediction as judged against the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet). Results: Nine teams submitted 13 forecasts for all required milestones. The first forecast was due on December 2, 2013; 3/13 forecasts received correctly predicted the start of the influenza season within one week, 1/13 predicted the peak within 1 week, 3/13 predicted the peak ILINet percentage within 1 %, and 4/13 predicted the season duration within 1 week. For the prediction due on December 19, 2013, the number of forecasts that correctly forecasted the peak week increased to 2/13, the peak percentage to 6/13, and the duration of the season to 6/13. As the season progressed, the forecasts became more stable and were closer to the season milestones. Conclusion: Forecasting has become technically feasible, but further efforts are needed to improve forecast accuracy so that policy makers can reliably use these predictions. CDC and challenge contestants plan to build upon the methods developed during this contest to improve the accuracy of influenza forecasts. © 2016 The Author(s)

Knowledge and behaviors related to dietary salt and sources of dietary sodium in north India

Sodium, an element needed for the normal human physiology is known to be associated with high blood pressure and other consequences if consumed in excess. The assessment of knowledge and behavior related to sodium that is consumed in the form of salt plays an important role in the control of cardiovascular diseases. To control the intake of sodium, dietary sources of sodium need to be identified. To address this, a community-based cross-sectional study was conducted among women aged 20 to 59 years in north India, where knowledge, attitude, and behavior questionnaire given by the World Health Organization and 24-h dietary recall were used. The mean age of the participants was 34.5 years, and the majority of them were homemakers. Approximately, 80% of the participants believed that high salt diet causes serious health problems, and only 5% of the participants were aware of the existence of a recommendation for daily salt intake. Less than 20% of the participants took measures to control their salt intake. Vegetable-based dishes were found to be the major contributors to the daily salt intake followed by pulse-based and cereal-based dishes. This is because of the high quantity in which they are consumed. Food cooked at home contributed to 90% of the daily salt intake. To control the salt intake, we should cut- down the discretionary salt use. Dietary advice should be customized to the individual, and the family physician plays an important role in this. Behavioral change is the need of the hour to control the epidemic of non-communicable diseases

Effect of Moisture Sorption On Free Volume and Relaxation of Spray Dried Dispersions: Relation to Drug Recrystallization

The effect of vapor sorption on the free volume of drug-polymer spray dried dispersions (SDDs) was investigated, along with the crystallization propensity of drug molecules in SDDs after exposure to humidity. Subsequently, the correlation of free volume change and relaxation time with drug recrystallization was examined. Four polymers, including polyvinylpyrrolidone (PVP], polyvinylpyrrolidone vinyl acetate copolymer (PVPVA], hydroxypropyl cellulose (HPC] and hydroxypropyl methylcellulose acetate succinate (HPMCAS), and two drugs (indomethacin and ketoconazole) were selected for preparing SDDs. Free volume data of the exposed SDDs were obtained with positron annihilation lifetime spectroscopy (PALS) while the relaxation time was measured using a TA rheometer. Additionally, the crystallization propensity of APIs in the exposed SDDs was assessed using both polarized light microscopy (PLM) and powder X-ray diffraction (PXRD), followed by relating API crystallization inclination with expansion of holes and relaxation time. Finally, Cohen and Turnbull molecular transport model, along with its extensions by Vrentas and Duda, was qualitatively utilized for interpreting the recrystallization propensity of API molecules. In conclusion, API recrystallization is closely related to free volume change upon moisture sorption and relaxation time, but system dependent; overall, drug-HPMC-AS SDDs appear physically stable against recrystallization due to less increase in free volume

An updated checklist of shrimps on the Indian coast

This study reports an updated checklist of marine shrimps found along the Indian coast, including the Lakshadweep and the Andaman &amp; Nicobar Islands.  A total of 364 species classified under 128 genera belonging to the order Decapoda is reported, thus adding 27 species to the existing checklist of 337 species.  Marine shrimps are classified under two suborders of the order Decapoda, viz., Dendrobranchiata and Pleocyemata, and the two suborders account for 155 (42.6 %) and 209 species (57.4 %) of these 364 species, respectively.  Pleocyemata is represented by three infraorders, viz., Axiidea, Caridea and Stenopodidea, while Caridea has a maximum of 199 reported species. Among the 12 superfamilies, Penaeoidea contributed to 38.13% (135 species) followed by Paleaemonidea with 18.07% (64 species).  All other superfamilies were found to contribute less than 12%.  Superfamilies, Bresilloidea and Psalidopodoidea had only single species representatives (0.28% each).  The final list was compiled after reviewing all existing literature including monographs, catalogues, checklists, websites and fishery reports. The scientific names were validated with the World Register of Marine Species (WoRMS) database.  A total of 25 issues were identified from the previous checklist out of which 19 species have been updated with the correct, accepted names and six species have been removed from the previous list.</p

Understanding Drug Resistance of Wild-Type and L38HL Insertion Mutant of HIV-1 C Protease to Saquinavir

Acquired immunodeficiency syndrome (AIDS) is one of the most challenging infectious diseases to treat on a global scale. Understanding the mechanisms underlying the development of drug resistance is necessary for novel therapeutics. HIV subtype C is known to harbor mutations at critical positions of HIV aspartic protease compared to HIV subtype B, which affects the binding affinity. Recently, a novel double-insertion mutation at codon 38 (L38HL) was characterized in HIV subtype C protease, whose effects on the interaction with protease inhibitors are hitherto unknown. In this study, the potential of L38HL double-insertion in HIV subtype C protease to induce a drug resistance phenotype towards the protease inhibitor, Saquinavir (SQV), was probed using various computational techniques, such as molecular dynamics simulations, binding free energy calculations, local conformational changes and principal component analysis. The results indicate that the L38HL mutation exhibits an increase in flexibility at the hinge and flap regions with a decrease in the binding affinity of SQV in comparison with wild-type HIV protease C. Further, we observed a wide opening at the binding site in the L38HL variant due to an alteration in flap dynamics, leading to a decrease in interactions with the binding site of the mutant protease. It is supported by an altered direction of motion of flap residues in the L38HL variant compared with the wild-type. These results provide deep insights into understanding the potential drug resistance phenotype in infected individuals

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Not AvailableSpecies checklists enlist the species available within the defined geographical region and thus serve as essential input for developing conservation and management strategies. The fields of conservation biology and ecology confront the chal-lenge of inflated biodiversity, attributed to non-recognition of taxonomic inconsistencies such as synonyms, alternate rep-resentation, emendations etc. Critical review of the checklists and distributional records of Phylum Echinodermata from Indian waters and subsequent validation of species names with World Register of Marine Species (WORMS) database, re-vealed that the current literature included 236 incorrect entries comprising of 162 synonyms, 15 emendations, 5 nomina dubia, I nomen nudwn, 40 species under alternate representation, 9 species with author misnomer, 1 subspecies and 1 un-accepted. The 226 species found to be mixed with valid names and a revised checklist was prepared. The revised and up-dated checklist holds 741 species of echinoderms comprising of 182 asteroids (24.56%), 70 crinoids (9.45%), 138 echinoids (18.62%), 179 holothuroids (24.16%) and 172 ophiuroids (23.21%), placed under 28 orders and 107 families. This paper discusses the cause for taxonomic inflation and argues that such taxonomic inconsistencies alter our interpre-tations of a species including its inaccurate distribution and, could possibly impede the country's conservation and man-agement efforts.Not Availabl