Impact of reaction temperature,stirring and cosolvent on the solvothermal synthesis of anatase TiO2 and TiO2/titanate hybrid nanostructures: Elucidating the growth mechanism

One-dimensional anatase TiO₂ and hybrid TiO₂/titanate nanostructures are synthesized by a simple low temperature solvothermal route followed by the Na⁺/H⁺ ion-exchange and final calcination process. We investigated the impact of reaction temperature, stirring conditions and cosolvent on the morphologies of the as-prepared nanostructures. Nanotubes and nanorods are formed in alkaline solution, while nanorods/nanowires and nanoporous nanoribbons are formed in alkaline water–ethanol and alkaline water–ethylene glycol mixed solvents, respectively. X-ray diffraction, Raman scattering and high-resolution transmission electron microscopy studies are employed to identify the structure and phase composition. The formation of different morphologies of the as-synthesized nanostructures is investigated by field emission scanning electron microscopy and transmission electron microscopy. The growth mechanism and reaction process of the as-prepared nanostructures are explained based on the experimental observations. The photoluminescence, optical absorption and the tuning of band gap of the prepared samples are also studied. This work will be valuable for understanding the growth mechanism of various nanostructured TiO₂ and to explore the commercial applications of nanoporous nanoribbons of TiO₂.     

Geographic variation in the flavour volatiles of Alphonso mango

Alphonso, one of the most popular cultivars of mango in India is known to exhibit geographic variation in the flavour of ripe fruits. To get chemical insight into this difference, volatiles were studied in the ripening fruits of Alphonso mangoes from three cultivation locations in India. Ripe fruits from Deogad had lower content of mono- and sesquiterpenes and higher content of lactones and furanones as compared to the fruits from Dapoli; whereas fruits from Vengurle had average quantities of these chemicals in comparison with Deogad and Dapoli fruits. This variation was clearly reflected as separate clustering of the localities in the Principal Component Analysis. The localities were indistinguishable from each other in terms of raw fruit volatiles. This study exemplifies a case of phenotypic plasticity; since the plants chosen were clonally propagated, such geographic variation in the volatiles can be attributed to varied abiotic conditions at these three localities.     

Clay incorporated wet laid wood pulp based wound dressing for severe hemorrhage

Abstract

Nonwoven mats used for hemostat wound dressing was prepared by miniature wet laid nonwoven technique using wood pulp and kaolin. The wood pulp was dispersed along with kaolin in water medium and was wet laid by altering the process parameters. Optimum concentration of kaolin that can be loaded in the Web was found to be 2 gpl. The PBS swelling of the wood pulp/kaolin mat was 110% higher compared to the wood pulp control sample. The blood coagulation time for wood pulp/kaolin was 100?s whereas for the control sample was 250?s. The developed nonwoven mats have tremendous potential in trauma wound care.     

Anisotropic Magnetocaloric Effect in Single-crystalline Pr0.52Sr0.48MnO3

We report the magnetocaloric effect (MCE) in a Pr_0.52Sr_0.48MnO₃ single crystal estimated from the isothermal magnetization curve using the Maxwell relation. Isothermal magnetization curves are measured over the range 20 K to 320 K where the field was applied parallel (??) and perpendicular (??) to the [110] direction of the perovskite structure with Pbnm space group. A peak in the temperature (T) dependence of magnetic entropy change (??S _M) with a fairly large negative value (???3.3 J/kg?K) is observed at 275 K close to the Curie temperature (T _C) for a change in field of ??H=40 kOe. The ?? and ?? components of ??S _M deviate from each other below ??260 K and an inverse MCE is observed below ??150 K. We note that the Landau theory of phase transitions satisfactorily explains the ??S _M vs T plot around the second-order transition at T _C.     

Agave sisalana,a biosorbent for the adsorption of Reactive Red 120 from aqueous solution

The textile industry is one of the largest producers of dye effluent. Treatment of these effluents has to be cost effective hence a number of precursors have been studied as a viable alternative adsorbent. Sisal fibre was converted to activated carbon by chemical methods. Sisal fibre was activated with different activating agents such as H₃PO₄, HCl, HNO₃, NaOH and KOH. The adsorption of Reactive Red 120 (RR 120) dye onto sisal fibre activated carbon (SFAC) from aqueous solution was investigated. Adsorption experiments were carried out at different dye concentrations, initial solution pH and carbon dosage. Batch adsorption studies were carried out using activated carbon produced using phosphoric acid yielded better carbon as it good results in terms of Methylene Blue number and Iodine number. These carbons were used to study the batch adsorption studies. Methylene Blue number and Iodine number of SFAC were found to be 240 mg/g and 855 mg/g, respectively. The BET surface area of the carbon was 885 m²/g. The batch experiments adsorption isotherm studies fitted well to Langmuir isotherm and the adsorption capacity was found to be 110 mg/g. Adsorption kinetics data were tested using pseudo-first-order and pseudo-second-order models. Kinetic studies showed that the adsorption data followed a pseudo-second-order reaction.     

Biodegradation of endosulfan isomers in broth culture and soil microcosm by Pseudomonas fluorescens isolated from soil

Bacterial isolates from endosulfan-contaminated soil were grown in minimal medium and screened for endosulfan degradation. The isolate which used endosulfan and showed maximum growth was selected for detailed study. Maximum degradation in shake flask culture by Pseudomonas fluorescens was 92.80% of α and 79.35% of β endosulfan isomers in 15?days at 20?mg/L concentration, followed by 50 and 100?mg/L, while the corresponding values in static condition were 69.15 and 51.39%, respectively. Endosulfan concentration degradation declined significantly at 50 and 100?mg/L. Concomitant to degradation, release of chloride ion exhibited positive relation, while pH decreased from 7.0 to 4.53 in agitating and 7.0–5.18 in static condition. The soil microcosm study revealed maximum endosulfan degradation in sterilized soil amended with P. fluorescens. Endosulfan diol and endosulfan ether were among the products of endosulfan metabolism in broth culture, but only endosulfan ether was detected in the soil microcosm. Endosulfan sulphate, a persistent and toxic metabolite of endosulfan, was not detected in either case. The study showed that P. fluorescens could be used effectively for bioremediation of the pesticide contaminated sites.     

Spatial and temporal changes in the volatile profile of Alphonso mango upon exogenous ethylene treatment

Alphonso is a highly favoured and exported mango cultivar among the vast mango germplasm of India. Being a climacteric fruit, ethylene plays an important role in ripening of mango. For deeper understanding of effect of pre-climacteric ethylene treatment on volatile profiles of Alphonso mango, 26 volatiles were tracked through six ripening stages of pulp and skin of ethylene-treated and control Alphonso fruits. The study revealed accelerated ripening in terms of early appearance of ripening-specific compounds, lactones and mesifuran, upon ethylene treatment. While the level of lactones remained unaffected, the mesifuran level vastly increased upon ethylene treatment. Skin showed high terpene content while pulp had higher amount of lactones compared to skin. This work points towards involvement of ethylene as a natural hormone in the biosynthesis of lactones and furanones in naturally ripened fruits; whereas, an increase in the terpene level during ripening appears to be independent of ethylene.