Biogenic fabrication of CuNPs,Cu bioconjugates and in vitro assessment of antimicrobial and antioxidant activity

In the present study, the authors synthesised copper nanoparticles (CuNPs) by using extract of Zingiber officinale (ginger) and later the NPs were bioconjugated with nisin, which shows antimicrobial activity against food spoilage microorganisms. CuNPs and its bioconjugate were characterised by ultraviolet–vis spectroscopy, NP tracking analysis, Zetasizer, transmission electron microscopy analysis, X‐ray diffraction and Fourier transform infra‐red (FTIR) spectroscopy. Zeta potential of CuNPs and its bioconjugate were found to be very stable. They evaluated in vitro efficacy of CuNPs and its bioconjugate against selected food spoilage bacteria: namely, Staphylococcus aureus, Pseudomonas fluorescens, Listeria monocytogenes and fungi including Fusarium moniliforme and Aspergillus niger. Antimicrobial activity of CuNPs was found to be maximum against F. moniliforme (18 mm) and the least activity was noted against L. monocytogenes (13 mm). Antioxidant activity of CuNPs and ginger extract was performed by various methods such as total antioxidant capacity reducing power assay, 1‐1‐diphenyl‐2‐picryl‐hydrazyl free radical scavenging assay and hydrogen peroxide assay. Antioxidant activity of CuNPs was higher as compared with ginger extract. Hence, CuNPs and its bioconjugate can be used against food spoilage microorganisms.Inspec keywords: antibacterial activity, biomedical materials, copper, nanoparticles, nanofabrication, nanomedicine, microorganisms, ultraviolet spectra, visible spectra, electrokinetic effects, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectra, free radical reactions, food technologyOther keywords: biogenic fabrication, Cu bioconjugates, in vitro assessment, antimicrobial activity, antioxidant activity, copper nanoparticles, Zingiber officinale, ultraviolet‐visible spectroscopy, NP tracking analysis, Zetasizer, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, FTIR, zeta‐potential, food spoilage bacteria, Staphylococcus aureus, Pseudomonas fluorescens, Listeria monocytogenes, fungi, Fusarium moniliforme, Aspergillus niger, F. moniliforme, L. monocytogenes, ginger extract, total antioxidant capacity, power assay, 1‐1‐diphenyl‐2‐picryl‐hydrazyl free radical scavenging assay, hydrogen peroxide assay, food spoilage microorganisms, Cu     

Correlation between stability of a protein and its dipeptide composition: a novel approach for predicting in vivo stability of a protein from its primary sequence

Statistical analysis of 12 unstable and 32 stable proteins revealedthat there are certain dipeptides, the occurrence of which issignificantly different in the unstable proteins compared withthose in the stable ones. Based on the impact of these dipeptideson the unstable proteins over the stable ones, a weight valueof instability is assigned to each of the dipeptides. For agiven protein the summation of these weight values normalizedto the length of its sequence helps to distinguish between unstableand stable proteins. Results suggest that the in vivo instabilityof proteins is possibly determined by the order of certain aminoacids in its sequence. An attempt is made to correlate metabolicstability of proteins with features of their primary sequencewhere weight values of instability for a protein of known sequencecould thus be used as an index for predicting its stabilitycharacteristics.     

Gas hold-up behavior of mechanically agitated gas-liquid reactors using pitched blade downflow turbines

Fractional gas holdup was measured in 0.57, 1.0, and 1.5 m i.d. vessels. Pitched blade downflow turbines (PTD) were used as the impeller. Design details of the impeller, such as the impeller diameter (0.22 T to 0.5 T) and blade width (0.25 D to 0.4 D), were studied. The effect of sparger type, geometry and size on fractional gas hold-up has been investigated in detail. Four different types of spargers (pipe, conical, ring and concentric ring spargers) were used. Sparger location was varied for all the types studied. Further, design details of the ring sparger, which gave the highest hold-up were then studied in detail. These included ring diameter, number of holes and hole size. All the reported correlations for fractional gas hold-up in mechanically agitated gas-liquid reactors were tested and compared. A better correlation has been developed for pitched blade turbines.     

Petroleum Residue Upgrading Via Delayed Coking: A Review

World petroleum residue processing capacity has reached about 725 million metric tons per annum (MMTPA). The high demand for transportation fuels and the ever-rising heavy nature of crude oil have resulted in a renewed interest in the bottom-of-the-barrel processing using various conversion processes. Delayed coking, known for processing virtually any refinery stream (which not only poses a serious threat to environment, but also involves a disposal cost) has garnered tremendous importance in the current refining scenario. Needle coke obtained from delayed coking process is a highly sought-after product, which is used in electric arc furnaces (in the form of graphite electrodes) in steel making applications. In the present communication, the published literature has been extensively analyzed and a state-of-the-art review has been written that includes: (1) importance and place of delayed coking as a residue upgrading process in the current refining scenario; (2) coking mechanism and kinetics; (3) design aspects; (4) feedstocks suitable for the production of needle coke; (5) characteristics of needle coke; (6) factors affecting needle coke quality and quantity; and (7) future market for needle coke. An attempt has been made to get the above-mentioned aspects together in a coherent theme so that the information is available at a glance and could be of significant use for researchers and practising refiners.     

A stochastic approach to the mode of deformation and contact between rough surfaces

The real area of contact between a rough and an ideally flat surface is evaluated from the spectral moments of the profile of the rough surface. A stochastic criterion for plastic deformation of the asperities is developed and applied to determine the percentage of plastic and elastic deformation in the total area of contact at a given separation. An illustration is given to delineate the theory through experimental profile data obtained from a ground surface.     

Environmental impact assessment of river valley projects in upper Teesta basin of Eastern Himalaya with special reference to fish conservation: a review

Teesta river basin in Eastern Himalaya is being subjected to cascade hydropower development. To assess the impacts of this developmental activity on fish fauna of the basin, fish habitats of the four largest tributaries in the basin were selected for the present study. A total of 18 large hydroelectric projects are planned on these rivers. Here, a total of 11 EIAs and 2 carrying capacity studies in Teesta basin were reviewed. Our investigations show that after commissioning all the projects, 52–88% of the free-flowing river stretches will be diverted and 7.6–24% of the riverine ecosystems will be converted into semi lacustrine ecosystems in different rivers. The cascade hydropower development is likely to affect more than 100 fish species. All the EIA reports reviewed have investigated fish species richness, impacts on fish fauna and fishery management plans. EIA studies and management plans, however, do not adequately address important ecological and conservation issues due to various limitations. An integrated fish conservation plan for the upper Teesta basin is suggested in this contribution.