Samarium Ion-Doped Maghemite Nanoparticles: Synthesis,Microstructural, Optical,and Magnetic Characterizations

Journal of Superconductivity and Novel Magnetism - This paper reports the effects of rare-earth Sm3+ ion substitution on structural, optical, electronic, and magnetic responses of maghemite...     

An adaptive plant leaf mobile informatics using RSSC

Multimedia Tools and Applications - An automated plant biometric system is now an important step in preserving nature’s biodiversity. This paper presents a novel Relative Sub-image Sparse...     

<Emphasis Type="Bold">Analysis of Spatio-temporal Characteristics and Regional Frequency of Droughts in the Southern Peninsula of India</Emphasis>

A detailed regional drought study is carried out in the southern peninsula of India to characterize the spatio-temporal nature of droughts and to predict the drought magnitudes for various probabilities in the homogeneous drought regions. The method of several random initializations of the cluster centres of the K-means algorithm is suggested for the identification of the initial regions in the context of drought regionalization, which is shown to perform better than the initialization from the Ward’s algorithm and the Ward’s algorithm itself. The peninsula is classified into seven spatially well-separated homogeneous drought regions. The robust L-moment framework is used for the regional frequency analysis of drought magnitudes computed using the standardized precipitation index. The Pearson type III is found to be appropriate for regional drought frequency analysis in six of the regions, while the robust Wakeby distribution is suggested for one region. Low magnitude droughts are frequent and dominant in the northern part of west coast, the north-eastern coast and its adjoining inland region, while high magnitude droughts are less in number and are experienced in semi-arid central part, southern part of western coast, south-eastern part and north-western inland region. The spatial maps of drought magnitudes indicate that at higher return periods (100 and 200 years) the south-eastern part of the peninsula is likely to encounter high magnitude droughts, while the central region is likely to experience the same at lower return periods (10 and 50 years). Hence these regions need to be given special importance in the drought mitigation planning activities.     

Carbohydrate polymers of chirata (Swertia chirata) leaves: Structural features, in vitro anti-oxidant activity and fluorescence quenching study

Chirata (Swertia chirata) is widely used in Indian folk medicine for the prevention of various disorders. Herein, we analyzed the water-extracted carbohydrate polymer (WECP) of this herb using chemical, chromatographic, and spectroscopic methods. The anti-oxidant capacity of this fraction was studied by ferric reducing anti-oxidant power (FRAP) and DPPH radical assays. Effect of WECP on bovine serum albumin spectrum (BSA) was determined using excitation wavelength of 282 nm. Anion exchange chromatography of WECP yielded 5 fractions (F1–F5) with different chemical compositions. The major fraction (F5) was homogeneous, had an apparent molecular mass of 4.5 kDa, and contains both carbohydrates (57%) and phenolics (34%). The anti-oxidant capacities of WECP and F5 were comparable to standard anti-oxidants. Notably, activities of the carbohydrate polymers (F1–F5) correlate with their phenolics content. Fluorescence quenching measurement suggests that F5 can form complex with BSA and the value of the binding constant is K=6.28×10⁵/M.     

Oxidation and Oxidative Bromination Reactions Catalyzed By a Reusable Polymer-Anchored Iron(III) Complex in Water at Room Temperature

A polymer-anchored iron(III) catalyst was synthesized and characterized. Its catalytic activity was evaluated for the oxidation of various alkenes, sulfides, aromatic alcohols and ethylbenzene with 30 % H₂O₂ as the oxidizing agent. The catalyst was also effective for the oxidative bromination reaction with 80–100 % selectivity of monobrominated products with H₂O₂/KBr at room temperature. The above reactions require a minimum amount of H₂O₂ and short reaction time. Most importantly, all the above reactions occur in aqueous medium. The catalyst can be facilely recovered and reused six-atimes without significant decrease in its activity and selectivity.     

Water‐soluble ionic polythiophenes for biological and analytical applications

Ionic polythiophenes are important conjugated polymers because of their excellent optical properties and water solubility. They are classified as cationic, anionic and zwitterionic conjugated polyelectrolytes. This review article describes concisely their biological and analytical applications. The specific detection of different negatively charged biomolecules such as DNA and adenosine triphosphate, anions like halides and toxic pseudo‐halide (CN ^?) and environmental pollutants, e.g. surfactants, is discussed. The conformational changes of cationic polythiophenes (CPTs ) induced by various analytes due to formation of ionic conjugates and the cooperative responses of all segments cause dominant signal amplification even in the presence of a small perturbation. In addition, reactive oxygen scavenging, antimicrobial photosensitizing and cell imaging applications of CPTs are documented. Use of anionic polythiophenes for sensing of protamine and cations like Cu²⁺ and Ca²⁺ is also discussed. Finally, sensing of DNA , peptides and surfactants by zwitterionic polythiophenes is included. The concluding part discusses future prospects. © 2016 Society of Chemical Industry     

Dextrin crosslinked with poly(lactic acid): A novel hydrogel for controlled drug release application

A new class of biodegradable crosslinked hydrogel, consisting of hydrophobic polylactic acid (PLA) and hydrophilic dextrin in presence of crosslinker N,N‐methylene bisacrylamide (MBA) has been synthesized by free‐radical polymerization technique using potassium persulfate (KPS) as initiator. By variation of crosslinker concentration, a series of hydrogels have been prepared and the optimized grade has been selected on the basis of higher crosslinking efficiency as well as lower equilibrium swelling characteristics, XRD analysis. The hydrogels have been characterized by FTIR spectra, ¹³C‐NMR spectra, CHN analysis, SEM analysis, swelling characteristics, and toxicity study. In vitro release study of model drugs (ciprofloxacin and ornidazole) from hydrogel matrix has been performed in various buffer solutions at 37°C. The drug release kinetics and mechanism have been studied using zero order, first‐order kinetic models, Korsemeyar–Peppas model, Higuchi model, Hixson–Crowell model, and nonlinear Kopcha model. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40039.     

CO2‐induced crystal engineering of polylactide and the development of a polymeric nacreous microstructure

Nacre's biomineralization process and its self‐organizing brick‐and‐mortar crystalline microstructure have inspired many researchers to develop new materials derived from the natural world. In our study, we took a novel approach to two‐dimensional (2‐D) crystallization. That is, we applied the biomineralization self‐organizational principle that exists in natural materials to a biopolymer (polylactide). The CO₂‐induced crystallization of poly(d ‐lactide), with its unique diffusion‐controlled crystallization mechanism, tends to produce distinct 2‐D spherulitic structures. We found that these 2‐D spherulites were self‐organizing in nature, and that they created a stack of 2‐D spherulitic structures. These crystalline microstructures, with their intervening amorphous phase, were foamed in situ due to the CO₂‐induced crystallization self‐exclusion phenomenon. We compared the resultant crystalline structure with nacre's brick‐and‐mortar crystalline microstructure to confirm the biomimetic principle of self‐organization. To the best of our knowledge, this is the first time that a biopolymer has been crystallized in a 2‐D manner in a way that resembles nature's biomineralization process. The hierarchical crystalline microstructure is morphologically similar to that of nacre biomaterials. This novel crystallization technique is simple, absolutely non‐toxic and works swiftly to produce a brick‐and‐mortar crystalline microstructure with a high degree of order. © 2017 Society of Chemical Industry