Shiv Singh

Preparation of surfactant-mediated silver and copper nanoparticles dispersed in hierarchical carbon micro-nanofibers for antibacterial applications

The antibacterial potential of copper (Cu) and silver (Ag) nanoparticles dispersed in a phenolic resin precursor-based multi-scale web of carbon microfibers (ACFs) and nanofibers (CNFs) was assessed in this study. The multi-scale web of ACF/CNF was prepared by growing the CNFs on the ACF substrate by chemical vapor deposition (CVD). The Ag or Cu nanoparticles were used as the catalyst, and acetylene (C2H2) gas was used as the carbon source. An anionic surfactant, sodium dodecyl sulfate (SDS), was used for the preparation of the Cu/Ag-ACF composites to prevent the agglomeration of Cu(II) and Ag(I) ions and achieve a uniform mono-dispersion during the impregnation step. The prepared composites with Cu and Ag dispersed in the ACF and ACF/CNF were characterized using several analytical techniques, including atomic absorption spectroscopy (AAS), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and thermal programming reduction (TPR). The antibacterial properties of the prepared multi-scale or hierarchical structures were evaluated against the gram-negative bacteria Escherichia coli (E. coli) and the gram-positive bacteria Staphylococcus aureus (S. aureus). The results revealed that the prepared Ag-ACF/CNFs were highly effective against these bacteria, achieving a complete inhibition of bacterial growth for over 72 hours.

Effect of Hurdle Technology in Food Preservation: A Review

Hurdle technology is used in industrialized as well as in developing countries for the gentle but effective preservation of foods. Hurdle technology was developed several years ago as a new concept for the production of safe, stable, nutritious, tasty, and economical foods. Previously hurdle technology, i.e., a combination of preservation methods, was used empirically without much knowledge of the governing principles. The intelligent application of hurdle technology has become more prevalent now, because the principles of major preservative factors for foods (e.g., temperature, pH, aw, Eh, competitive flora), and their interactions, became better known. Recently, the influence of food preservation methods on the physiology and behavior of microorganisms in foods, i.e. their homeostasis, metabolic exhaustion, stress reactions, are taken into account, and the novel concept of multi-target food preservation emerged. The present contribution reviews the concept of the potential hurdles for foods, the hurdle effect, and the hurdle technology for the prospects of the future goal of a multi-target preservation of foods.

The interaction between ethanol and manganese in rat brain

The effect of combined administration of ethanol and manganese on the brain tissue of rats was investigated to evaluate the role of alcohol ingestion in inducing susceptibility to manganese poisoning. Ethanol and manganese alone and the combination of the two were administered orally daily to the rats for 30 days. Almost identical increase in the brain contents of manganese in rats receiving the metal alone and in combination with ethanol indicates that ethanol administration does not influence the accumulation of manganese in that organ. The copper contents of brain also increased to almost the same extent in these two groups. Synergistic effect of ethanol and manganese was noticed on increasing the activity of ATPase and RNase while marked antagonistic effect was observed on the activity of MAO. The mechanism and the significance of these neurochemical alterations occurring after the administration of ethanol and manganese have been discussed.

Multi-scale carbon micro/nanofibers-based adsorbents for protein immobilization

In the present study, different proteins, namely, bovine serum albumin (BSA), glucose oxidase (GOx) and the laboratory purified YqeH were immobilized in the phenolic resin precursor-based multi-scale web of activated carbon microfibers (ACFs) and carbon nanofibers (CNFs). These biomolecules are characteristically different from each other, having different structure, number of parent amino acid molecules and isoelectric point. CNF was grown on ACF substrate by chemical vapor deposition, using Ni nanoparticles (Nps) as the catalyst. The ultra-sonication of the CNFs was carried out in acidic medium to remove Ni Nps from the tip of the CNFs to provide additional active sites for adsorption. The prepared material was directly used as an adsorbent for proteins, without requiring any additional treatment. Several analytical techniques were used to characterize the prepared materials, including scanning electron microscopy, Fourier transform infrared spectroscopy, BET surface area, pore-size distribution, and UV-vis spectroscopy. The adsorption capacities of prepared ACFs/CNFs in this study were determined to be approximately 191, 39 and 70 mg/g for BSA, GOx and YqeH, respectively, revealing that the carbon micro-nanofibers forming synthesized multi-scale web are efficient materials for the immobilization of protein molecules.

Development of dynamic test cases in OPAL-RT real-time power system simulator

The paper describes the development of the dynamic models of a number of commonly used test power systems in OPAL-RT real-time simulator environment. The process of building the dynamic test cases is described, and the challenges faced during such development are discussed. The performance of the dynamic test cases is investigated under various disturbances such as single-line-to-ground fault, line outages, step load change, and tap changing of on-load tap changers.

HHT-based classification of composite power quality events

Purpose – An electrical power system is expected to deliver undistorted sinusoidal, rated voltage and current continuously to the end-users. The problem of power quality (PQ) occurs when there is (are) deviation(s) in voltage and/or current which cause(s) failure or mal-operation of the customers equipments. Various methods are suggested to detect and classify single PQ event in a power system, the performance of such methods to classify composite PQ events is limited. The purpose of this paper is the classification of composite PQ events in emerging power systems. Design/methodology/approach – This paper proposes an effective method to classify composite PQ events using Hilbert Huang transform (HHT). The performance of probabilistic neural network (PNN) classifier and support vector machine (SVM) classifier to efficiently classify composite PQ events is compared. Findings – The features extracted from HHT are simple yet effective. SVMs and PNN classifiers are used for PQ classification. It is found that...

Candle soot derived carbon nanoparticles: Assessment of physico-chemical properties, cytotoxicity and genotoxicity

In this study, an evaluation of physico-chemical properties, cytotoxicity and genotoxicity of candle soot derived carbon nanoparticles (CNPs) was carried out. Several physico-chemical characterizations including scanning electron microscopy, transmission electron microscope, Brunauer-Emmet-Teller surface area and pore-size distribution, X-ray diffraction, Fourier transform infrared and Raman spectroscopy were implemented to characterize prepared CNPs. Propidium iodide uptake, reactive oxygen species assay and trypan blue exclusion and comet assay tests were executed to determine the toxicity of CNPs. It is found that the CNPs have insignificant cytotoxicity and genotoxicity and could be used in diverse biological and environmental applications as an alternative to expensive less toxic carbon materials.

Inexpensive, effective novel activated carbon fibers for sample cleanup: application to multipesticide residue analysis in food commodities using a QuEChERS method

AbstractPhenolic resin based activated carbon fibers (ACFs) were applied for the first time as a reversed-dispersive solid-phase extraction (r-DSPE) sorbent. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was applied to determine 26 pesticides (organophosphates, organochlorines, synthetic pyrethroids, and herbicides) in different complex matrices, including cauliflower, cucumber, banana, apple, wheat, and black gram. Different physicochemical characterization techniques were used to investigate the engineering and structural properties of the r-DSPE sorbent. All the chromatographic analyses were performed with a gas chromatograph equipped with an electron capture detector. The recoveries of all 26 pesticides were acceptable (70–120%), with relative standard deviations of less than 15%. The limit of detection and the limit of quantification were 1.13–5.48 ng/g and 3.42–16.60 ng/g, respectively. In the original QuEChERS method, primary secondary amine is extensively used as the r-DSPE sorbent in the cleanup process, but it is eightfold more expensive than the ACFs used in this study. Therefore, the modified QuEChERS method using ACFs during the cleanup process is more efficient, cheaper, and more robust to determine pesticides from different types of matrices, including vegetables, grains, and fruits, and ACFs could be used as a cost-effective alternative to primary secondary amine. Graphical AbstractSample clean-up using PSA and ACF as r-DSPE sorbent in QuEChERS method