Efficient photocatalytic degradation of bisphenol A by green synthesized CuO decorated nickel hexacyanoferrate nanocomposite

Bisphenol A (BPA), a chemical additive in polycarbonate plastics and epoxy resins, is suspected to be an endocrine-disrupter. Extensive use and irregular treating methods have led to frequent detection of BPA in wastewater, raising demand for their removal by efficient nanomaterials-based technique. Nanocomposite CuO@NiHCF was synthesized via green method using Citrus aurantium peel extract. Crystalline structure (particle size <50 nm) of CuO@NiHCF was analysed by microscopic and spectroscopic analysis. This nanocomposite showed 97% degradation of BPA (50 mg L⁻¹) at neutral pH in sunlight. Moreover, improved particle stability (zeta potential: −56.2 mV; 2.0 eV) and high surface area, pore volume (81 m²g⁻¹, 13.9 nm) resulted from synergism of NiHCF (−26.3 mV; 2.4 eV), and CuO (−11.5 mV; 1.9 eV) led to efficient photodegradation of BPA. Degradation of BPA was found photo-adsorptive. Moreover, degradation was carried out by OH radicals based with ring-opening mechanisms by GC–MS. High efficiency and sustainability of CuO@NiHCF were revealed by its multiple reusability (n = 10), leading to a promising and sustainable photocatalyst.     

Studies on the salt concentration of a PVdF–PVC based polymer blend electrolyte

To investigate the effects of salt concentration, LiBF₄ was incorporated into a PVdF–PVC based polymer blend and thin electrolytes were prepared by solution casting technique. The obtained thin films were subjected to various characterizations such as FTIR, XRD and TG/DTA analysis to study their complex behaviour, amorphicity and thermal stability, respectively. The ionic conductivities of the electrolytes were measured by AC impedance. A PVdF (80)–PVC (20)–LiBF₄ (8 wt%) polymer electrolyte was found to have high conductivity compared to other complexes. Similar investigations were also repeated with a LiClO₄ salt in the above blend and the electrical conductivity was found to be higher in the polymer complex having 8 wt% of salt concentration.     

Chemo‐enzymatic synthesis and evaluation of novel structured phenolic lipids as potential lipophilic antioxidants

Chemo‐enzymatic synthesis of structured triacylglycerol bearing ferulic acid as a phenolic acid at sn‐1/3 position is described in the present work. Four compounds of varying chain lengths, namely 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐hexanoyloxy‐propyl ester, 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐octanoyloxy‐propyl ester, 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐dodecanoyloxy‐propyl ester, and 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐acrylic acid‐2,3‐bis‐9‐octadecenoyloxy‐propyl ester were synthesized, and their structures were confirmed by IR, NMR, and MS. Antioxidant activity of the structured phenolic lipids were evaluated using three different in vitro antioxidant assays such as 2, 2‐diphenyl‐1‐picrylhydrazyl free radical (DPPH^•) scavenging, antioxidant potency in lipid matrix using rancimat, and by the rate of inhibition of autoxidation of linoleic acid in micelles. Ferulic acid and dodecylgallate were used as reference antioxidant compounds. DPPH^• assay did not show any improvement in the antioxidant activity of ferulic acid with lipophilic modification. However, the antioxidant potency of the structured phenolic lipids measured by rancimat method as well as by the rate of inhibition of autoxidation of linoleic acid in micelle showed improvement in antioxidant activity compared to ferulic acid. This is probably due to better solubility of the synthesized phenolic lipids in a hydrophobic medium and appropriate anchorage in Tween 20 micelle. The observed activities of the structured phenolic lipids are comparable to dodecyl gallate in rancimat assay, but superior to dodecyl gallate in Tween 20 micellar system.     

Diabetes aggravates nanoparticles induced breakdown of the blood-brain barrier permeability, brain edema formation, alterations in cerebral blood flow and neuronal injury. An experimental study using physiological and morphological investigations in the rat

The possibility that diabetes aggravates nanoparticles induced blood-brain barrier (BBB) breakdown, edema formation and brain pathology was examined in a rat model. Engineered nanoparticles from metals Ag and Cu (50-60 mn) were administered (50 mg/kg, i.p.) once daily for 7 days in normal and streptozotocine induced diabetic rats. On the 8th day, BBB permeability to Evans blue and radioactive iodine (131I-sodium) was examined in 16 brain regions. In these brain regions alterations in regional CBF was also evaluated using radiolabelled (125I) carbonized microspheres (o.d. 15 +/- 6 microm). Regional brain edema and Na+, K+ and Cl- ion analysis were done in 8 selected brain regions. Histopathology was used to detect neuronal damage employing Nissl staining. Nanoparticles treatment in diabetic rats showed much more profound disruption of the BBB to Evans blue albumin (EBA) and radioiodine in almost all the 16 regions examined as compared to the normal animals. In these diabetic animals reduction in regional cerebral blood flow (CBF) was more pronounced than in normal rats. Edema development as seen using water content and increase in Na+ and a decrease in K+ ion were most marked in diabetic rats as compared to normal rats after nanoparticles treatment. Cell changes in the regions of BBB disruptions were also exacerbated in diabetic rats compared to normal group after nanoparticles treatment. Taken together, these observations are the first to show that diabetic rats are more susceptible to nanoparticles induced cerebrovascular reactions in the brain and neuronal damage. The possible mechanisms and significance of the present findings are discussed.     

A genetic algorithm for FMS part type selection and machine loading

Part type selection (PTS) and machine loading are two major problems in the production planning of flexible manufacturing systems. In this paper, we solve these problems by the use of genetic algorithms (GAs). We exploit the problem's MIP (mixed integer programming) model to make our GA more meaningful and less computation-intensive. The GA strategy is developed in three parts: solution coding, solution generation and solution recombination. In solution coding, we replace the original binary routing variables with integer variables and thus reduce the chromosome length significantly. In solution generation, the level of feasibility is the main concern. We divide the constraints into two categories: direct and indirect. The direct constraints involve only two variables each and are easily satisfied by context-dependent genes. Since the direct constraints form the major chunk of constraints, their satisfaction controls infeasibility to a large extent. The remaining indirect constraints are handled by the penalty function approach. The solution recombination involves crossover and mutation. The crossover is performed in two steps, the PTS swap followed by the routing swap, so that the feasibility level is not disturbed. With a similar intent, the mutation is allowed to operate only on selective genes. All the steps are illustrated with examples. Our GA is able to achieve optimum or near-optimum performance on a variety of objectives. A parametric study of GA factors is also carried out, indicating population size and mutation probability as influential parameters.     

Rapid synthesis of silver nanoparticles by Pseudomonas stutzeri isolated from textile soil under optimised conditions and evaluation of their antimicrobial and cytotoxicity properties

Present study utilised textile soil isolated bacterium Pseudomonas stutzeri to synthesise extracellular silver nanoparticles (AgNPs) under optimised conditions. The synthesised AgNPs were characterised using ultraviolet‐visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Optimisation showed AgNPs synthesis within 8 h using 2mM Ag nitrate at pH9, temperature 80°C and maximum absorbance toward 400 nm. TEM analysis revealed spherical shape AgNPs and reduction in size upto 8 nm was observed under optimised conditions. FTIR spectra confirmed presence of proteins bound to AgNPs act as reducing agent. AgNPs showed strong antibacterial activity against multi‐drug resistant (MDR) Escherichia coli and Klebsiella pneumoniae as demonstrated by disc diffusion and colony forming unit assays. Zone of inhibition increased with increasing concentration of AgNPs with maximum of 19 mm against E. coli and 17 mm against K. pneumoniae at concentration of 2 μg/disc. Furthermore, AgNPs did not show any cytotoxic effects on human epithelial cells as demonstrated by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay even at 2 μg/ml concentration of AgNPs. The results of the present study suggest that AgNPs can be synthesised rapidly under optimised conditions and show strong antimicrobial property against MDR pathogens without having toxicity effect on human epithelial cells.Inspec keywords: ultraviolet spectra, proteins, transmission electron microscopy, infrared spectra, Fourier transform spectra, visible spectra, microorganisms, toxicology, cellular biophysics, biomedical materials, antibacterial activity, nanomedicine, nanofabrication, nanoparticles, silverOther keywords: 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay, human epithelial cells, cytotoxic effects, K. pneumoniae, colony forming unit counting assays, disc diffusion, Klebsiella pneumoniae, Escherichia coli, multidrug resistant, stabilising agent, reducing agent, proteins, parametric optimisation, TEM, transmission electron microscopy, FTIR spectra, Fourier transform infrared spectroscopy, ultraviolet‐visible spectroscopy, bacterium, cytotoxicity properties, antimicrobial properties, textile soil, Pseudomonas stutzeri, silver nanoparticle synthesis     

Timing and Carrier Frequency Offset Estimation Using Selective Extended Cyclic Prefix for Correlation Sequence for OFDM Systems

In this paper a novel technique for timing and carrier frequency offset (CFO) estimation for orthogonal frequency division multiplexing (OFDM) systems is presented. This technique is a modification of extended cyclic prefix for correlation sequence (ECPCS) based technique, called as selective extended cyclic prefix for correlation sequence (SECPCS) based technique. In cyclic prefix (CP) based technique, magnitude of timing metric near the exact starting point of CP is quite similar which causes problem in timing estimation. SECPCS is utilized in order to increase the difference between magnitudes of timing metric at the exact starting point of time of CP and its adjacent timing instants. In SECPCS technique, first of all correlation length of CP is extended using available CP samples and then those sequences which enlarge the difference in the magnitude of timing metric is selected. In the proposed technique the difference between magnitude of timing metric at exact starting point and its adjacent timing instants is significantly large compared to the previous techniques. The performance of different techniques is evaluated in terms of mean square error (MSE) in estimation of timing and CFO estimate. Further signal-to-interference-plus-noise ratio (SINR) loss of different techniques in different channel conditions is also estimated. From the simulation results it is observed that under different channel conditions, performance of the proposed SECPCS based technique is significantly better than previous techniques.     

Defect‐Related Emissions and Magnetization Properties of ZnO Nanorods

A clear correlation between defect‐related emissions and the magnetization of ZnO nanorods synthesized by a one‐step aqueous chemical method is demonstrated. The relative contribution of the emission bands arising from various types of defects is determined and found to be linked with the size of the nanorods and annealing conditions. When the size of the nanorods and the annealing temperature are increased, the magnetization of pure ZnO nanorods decreases with the reduction of a defect‐related band originating from singly charged oxygen vacancies ($V_{\rm o}^ +$ ). With a sufficient increase of annealing temperature (at 900 °C), the nanorods show diamagnetic behavior. Combining with the electron paramagnetic resonance results, a direct link between the magnetization and the relative occupancy of the singly charged oxygen vacancies present on the surface of ZnO nanorods is established.