Designing and Judd–Ofelt evaluation of versatile luminescent Eu (III) complexes sensitized with β-diketone ligand for multifarious applications

The present research work entails the synthesis of one binary and four ternary red light−emitting Eu (III)-based complexes with 3-benzylidene-2,4-pentanedione as the main ligand and 1,10-phenanthroline, bathophenanthroline, neocuproine, and 4,4′-′dimethyl-2,2′-′bipyridyl as auxiliary ligands. The metal–organic framework of the series was elucidated using energy dispersive X-ray analysis, elemental analysis, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance. This Eu (III) series exhibits optimum thermal stability, making them a promising candidate for organic light-emitting diodes. On the basis of emission spectra, their optical parameters such as nonradiative and radiative decay rates, luminescence decay time, intrinsic quantum efficiency, and Judd–Ofelt intensity parameter were determined. The monocentric luminescence and Judd–Ofelt parameters reveal the absence of symmetry around the europium center. CIE chromaticity coordinates, correlated color temperature values, color purity, and asymmetric ratios authenticate the color coordinates of the complexes in red region. Optical band gap values lie within the range of wide band gap semiconductors, indicating their utilization in military radars and biological labeling.     

Application of calcium alginate immobilized and crude pectin lyase from Bacillus cereus in degumming of plant fibres

Abstract

In this study, the purified pectin lyase was immobilized in calcium alginate beads and compared with crude enzyme for application in degumming of buel and banana plant fibres. From the data of scanning electron microscopy (SEM), it was observed that untreated buel fibres were covered by non-cellulosic materials (pectin, hemicelluloses and waxes) and the surface of enzymatically treated buel fibres looked smoother. Also, the crude alkaline pectin lyase treated buel fibre exhibited a considerably cleaner surface, which suggested that the crude pectin lyase could provide better degumming effects in comparison to the immobilized pectin lyase. In case of banana fibre, the FTIR spectroscopy showed that both crude and immobilized alkaline pectin lyase treatments of banana plant fibres were equally efficient in degumming. The enzymatic degumming of buel and banana with crude pectin lyase resulted in maximum release of galacturonide after 24?h for buel and 15?h for banana fibre. The optimum temperature for degumming of buel and banana fibres with crude pectin lyase was found to be 50?°C and 45?°C, respectively. Also, the maximum galacturonide was released with 200 and 250?U of pectin lyase for buel and banana fibre, respectively.     

Effects of dual stress (high salt and high temperature) on the photochemical efficiency of wheat leaves (Triticum aestivum)

In this study, we have focused on those components of Photosystem (PS) II which are significantly affected by dual stress (high salt and temperature) on wheat as measured by Plant Efficiency Analyser (PEA). It was observed that some of the chlorophyll a fluorescence parameters were temperature dominated, while some other parameters were salt dominated. We have also observed additive effects for parameters like antenna size heterogeneity. An important observation was that in high temperature alone, the K-step was observed at 40 °C, while in case of dual stress, the K-step was observed at 45 °C, while the Chl a fluorescence transient of 40 °C?+?0.5 M?NaCl was quite similar to 35 °C transient curve. In the presence of salt, K-step was observed at higher temperature suggesting a protection of OEC by salt. Plants are under dual stress, but effect of temperature stress is less severe in presence of salt stress. Thus, we can say that salt stress caused partial prevention from high temperature stress but it did not cause complete protection of PS II.     

A functional approach toward xerogel immobilization for encapsulation biocompatibility of Rhizobium toward biosensor

Sol-gel derived silica has tremendous applications as a biocompatible scaffold for the immobilization of cells. The use of xerogel as a matrix in the blueprint of biosensors is an appealing proposition due to several inimitable characteristics of xerogels, primarily because of their high porous nature, amendable pore size, and exceptionally large internal surface area. Morphological （X-Ray Diffraction and Thermogravimmetric Analysis） and optical （Fourier Transform Infrared and UV-Vis absorption） studies of the silica matrices with entrapped Rhizobial （Rz） structure of the biomaterial has been made. Temporal and concentration dependent studies were conducted for impregnated samples; it showed that the response time for the new biosensor for determining the concentration of Rz is less than 20 min. In this work, first time a novel avenue to create a generic approach for the fabrication of biosensor has been created.     

Thermally stable Sm3+-doped alkali zinc alumino borosilicate (AZABS) glass for warm white light generation and w-LED applications

Samarium ion (Sm³⁺)-doped alkali zinc alumino borosilicate (AZABS) glass was synthesized via quick melt quench technique. Various spectroscopic studies like optical absorption, photoluminescence (PL) emission, PL excitation, temperature-dependent PL and PL decay kinetics were performed on the as prepared glass system. Under 402 nm excitation, three sharp bands at wavelengths 563, 599 and 645 nm corresponding to transitions ⁴G_5/2 → ⁶H_5/2, ⁶H_7/2 and ⁶H_9/2, respectively, can be seen in the PL emission spectra. The 0.25 mol% Sm³⁺ glass has the highest intensity for these emissions. The lanthanide interaction in the glass matrix is dipole–dipole in nature as was proven from Dexter's analysis. The direct bandgap of 0.25 mol% Sm³⁺-doped AZABS glass was calculated to be 2.88 eV. The lifetimes of the as prepared glass range from 1.93 ms for the lowest concentration of Sm³⁺ to 0.75 ms for the highest. From temperature dependent PL studies, the activation energy for 0.25 mol% Sm³⁺-doped AZABS glass was found to be 0.19 eV which shows high thermal stability of this glass. We propose to utilize these Sm³⁺-doped AZABS glasses for white-light emitting diodes (w-LEDs) and solid-state lighting (SSL) applications.     

Assessment of Genetic Diversity,Micromorphology and Antimicrobial Activity in Nepeta cataria L.

The mosquito repellent Nepetalactone rich Nepeta cataria L. (catmint) plant has a variety of therapeutic and industrial potential. Reports on the genetic diversity of N. cataria germplasm are minimal globally and need attention for adding a new variety into commercial cultivation. The present study, therefore, assessed the genetic diversity among thirteen half-sib genotypes of N. cataria using agro economic and phytochemical traits. The experimental set has shown substantial variation for agro economic traits studied. Among all the studied populations, fresh herb-based essential oil content ranged from 0.1 % to 0.3 %, with a grand mean of 1.67 %. However, the estimated oil yield ranged from 44.4 kg/h to 120.73 kg/h with an average of 71.34 kg/h. Among the eleven phytochemical constituents detected in different concentrations in the essential oil of experimental sets, 4aα,7α,7aα-Nepetalactone (67.9–87.5 %) constituted the significant proportion of essential oil. Altogether, based on mean comparison, the population NC8 was found to be promising for estimated oil yield and 4aα,7α,7aα-Nepetalactone content. The greater heritability estimates (h²bs) and genetic advance as percent of mean (GAM) were observed for important economic parameters, i. e., oil content, herb yield, and oil yield. The cluster analysis revealed the least interactions between various agro economic and phytochemical variables. The microscopic study of trichome showed a positive correlation of abaxial leaf surface with essential oil content. The promising antimicrobial potential of catmint oil was also observed against human health-related pathogens. The results infer from our study provide valuable insight for genetic improvement and product development in the catmint germplasm.     

Synthesis of rhamnolipid biosurfactant and mode of hexadecane uptake by Pseudomonas species

Background  

Microorganisms have devised ways by which they increase the bioavailability of many water immiscible substrates whose degradation rates are limited by their low water solubility. Hexadecane is one such water immiscible hydrocarbon substrate which forms an important constituent of oil. One major mechanism employed by hydrocarbon degrading organisms to utilize such substrates is the production of biosurfactants. However, much of the overall mechanism by which such organisms utilize hydrocarbon substrate still remains a mystery.