Biological activities of synthesized silver nanoparticles from <Emphasis Type="Italic">Cardiospermum halicacabum</Emphasis> L.

The present study focuses on the green synthesis of silver nanoparticles using aqueous extract of Cardiospermum halicacabum. AgNPs were confirmed by UV–Visible spectrophotometer analysis showed SPR at 424 nm. FT-IR analysis revealed biomolecules capping of the AgNPs. XRD pattern of synthesized AgNPs was found in face-centered-cubic crystal structure and average crystal size was 23 nm. SEM analyses of the synthesized AgNPs determine the spherical shape and EDX spectra confirmed the presence of silver ions. DLS studies revealed that the synthesized AgNPs showed the average size as 74 nm and Zeta potential value of AgNPs was ?34 mv. The C. halicacabum leaf extract synthesized AgNPs efficiency were tested against different bacterial pathogens MTCC-426 Proteus vulgaris, MTCC-2453 Pseudomonas aeruginosa, MTCC-96 Staphylococcus aureus, MTCC-441 Bacillus subtilis and MTCC-735 Salmonella paratyphi, and fungal pathogens Alternaria solani and Fusarium-oxysporum. The antioxidant ability of the AgNPs was tested and the results showed significant DPPH, hydroxyl and superoxide, radical scavenging activities.     

Plant growth-promoting rhizobacteria (PGPR) and its mechanisms against plant diseases for sustainable agriculture and better productivity

Plant growth-promoting rhizobacteria (PGPR) are specialized bacterial communities inhabiting the root rhizosphere and the secretion of root exudates helps to, regulate the microbial dynamics and their interactions with the plants. These bacteria viz., Agrobacterium, Arthobacter, Azospirillum, Bacillus, Burkholderia, Flavobacterium, Pseudomonas, Rhizobium, etc., play important role in plant growth promotion. In addition, such symbiotic associations of PGPRs in the rhizospheric region also confer protection against several diseases caused by bacterial, fungal and viral pathogens. The biocontrol mechanism utilized by PGPR includes direct and indirect mechanisms direct PGPR mechanisms include the production of antibiotic, siderophore, and hydrolytic enzymes, competition for space and nutrients, and quorum sensing whereas, indirect mechanisms include rhizomicrobiome regulation via. secretion of root exudates, phytostimulation through the release of phytohormones viz., auxin, cytokinin, gibberellic acid, 1-aminocyclopropane-1-carboxylate and induction of systemic resistance through expression of antioxidant defense enzymes viz., phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenyloxidases (PPO), superoxide dismutase (SOD), chitinase and β-glucanases. For the suppression of plant diseases potent bio inoculants can be developed by modulating the rhizomicrobiome through rhizospheric engineering. In addition, understandings of different strategies to improve PGPR strains, their competence, colonization efficiency, persistence and its future implications should also be taken into consideration.

     

D.C. conductivity and spectroscopic studies of polyaniline doped with binary dopant ZrOCl<Subscript>2</Subscript>/AgI

Aqueous binary dopant (ZrOCl₂/AgI) is used in different ratios such as 1:1, 1:2 and 2:1 (w/w) for chemical doping to enhance the conductivity of synthesized polyaniline (PANI). The doping of polyaniline is carried out using tetrahydrofuran as a solvent. Doped samples are characterized using various techniques such as I–V characteristics, UV-visible spectroscopy, X-ray diffractometry (XRD), FTIR and photoluminescence (PL) studies. A significant enhancement in d.c. conductivity has been observed with the introduction of binary dopant. UV-visible study shows that optical parameters change considerably after doping. Interestingly, both direct and indirect bandgaps are observed in the doped samples. XRD patterns show the semi-crystalline nature of doped polyaniline. FTIR study shows structural modifications in functional groups with doping in PANI. Photoluminescence spectra exhibit emission properties of the samples.     

S-,N-and C-doped ZnO as semiconductor photocatalysts:A review

In the past few decades,many novel non-metal doped ZnO materials have developed hasty interest due to their adaptable properties such as low recombination rate and high activity under the solar light exposure.In this article,we compiled recent research advances in non-metal(S,N,C)doped ZnO,emphasizing on the related mechanism of catalysis and the effect of non-metals on structural,morphological,optical and photocatalytic characteristics of ZnO.This review will enhance the knowledge about the advancement in ZnO and will help in synthesizing new ZnO-based materials with modified structural and photocatalytic properties.     

Studies on electrical conductivity and dielectric behaviour of PVdF–HFP–PMMA–NaI polymer blend electrolyte

Polymer blend electrolytes composed of poly(vinylidene fluoride-co-hexafluoro-propylene), poly(methyl methacrylate) and 1·0 M NaI as salt have been synthesized using solution caste technique by varying the PVdF(HFP)–PMMA blend concentration ratio systematically. A.c. impedance studies were performed to evaluate the ionic conductivity of the polymer electrolyte films. The highest ionic conductivity at room temperature for [PVdF(HFP)–PMMA(4:1)](20 wt%) – [NaI(1·0 M)](80 wt%) system is found to be 1·67 × 10^???2 S cm^???1. XRD studies reveal complete complexation of the salt in the polymeric blend systems. The temperature dependence conductivity has been performed in the range of 303–373 K and it is observed that it obeys the Arrhenius behaviour. It has been observed that the dielectric constant, ε _r and dielectric loss, ε _i, increases with temperature in the lower frequency region and is almost negligible in the higher frequency region. This behaviour can be explained on the basis of electrode polarization effects. Plot of real part, M _r and imaginary part, M _i vs frequency indicates that the systems are predominantly ionic conductors. The phenomenon suggests a plurality of relaxation mechanism.     

Extruded Potato Peel Functional Properties Affected by Extrusion Conditions

Extrusion cooking of potato peel waste from processing plants to im-prove food safety affects functional properties of these peels as a high-fiber ingredient in foods. The effects of barrel temperature (104°C and 143°C) and feed moisture (31, 33.5, and 36% d.b.) on extruder performance and physical and functional properties of peels were studied. Torque and die pressure decreased with barrel temperature; all variables affected melt temperature. Samples were darker at the higher temperature. Expansion, Hunter a, and powder bulk density decreased with both variables. Hydration capacity increased with feed moisture. Extruded peels differed from commercial fiber products in color, but hydration capacity was similar among extruded peels and cereal brans.     

Location of tuna resources in Indian waters using NOAA AVHRR data

Abstract

The world demand for tuna resources is ever increasing and there is scope for better economic returns in terms of foreign exchange earnings. It is one of the least exploited resources of the Indian seas. Remote sensing based studies on the tuna environment began in the seventies in the Gulf of Guinea. This study helped to establish a fishing strategy during the eighties. But so far this has not been attempted in Indian waters. With the basic understanding that most of the species of tuna respond directly to temperature, a study using NOAA AVHRR data was carried out to locate tuna resources. Thermal data of NOAA AVHRR for eight dates in the 1989-90 season were analysed to generate sea surface temperature (SST) images. Catch per unit effort (CPUE) of tuna longline data acquired from the Fishery Survey of India pertaining to fishing conducted by chartered vessels, was plotted on the SST images. Yellowfin tuna (YFT) comprises the maximum catch plus small quantities of marlins. It was observed that almost all the data points were located near the edge of warm water (27°-29°C). A relation between average CPUE of YFT and multi-channel sea surface temperature (MCSST) charts generated by OPC (the Ocean Products Centre) of NOAA was established. It shows on an average an increasing trend in the CPUE of YFT from 26° C (hooking rate ～ 1 per cent) to 29°C (hooking rate ～3 65 per cent) and then shows a drop with further rise in temperature. Since YFT is known to be present in a wide range of temperatures, it can be concluded that the location of warm water edges having a gradient of about 1°C and the above mentioned range of temperature will be desirable in locating tuna potential areas.