Synthesis of PVA/PVP based hydrogel for biomedical applications: a review

The composition and synthesis of hydrogel were developed by using Polyvinyl alcohol (PVA) and Polyvinylpyrrolidone (PVP). Polyvinyl alcohol (PVA) and Polyvinylpyrrolidone (PVP) based hydrogels are the most popular water-soluble, biodegradable, biocompatible, non-carcinogenic, and extremely low cytotoxicity synthetic polymers due to their good biocompatibility have been used in numerous biomedical applications, such as implants, artificial organs, drug delivery devices, and wound dressings. In this review paper, details of synthetic of hydrogel formulations with PVA and PVP for biomedical applications.     

Development and validation of a deep learning-based algorithm for drowsiness detection in facial photographs

Multimedia Tools and Applications - Drowsiness is a feeling of sleepiness before the sleep onset and has severe implications from a safety perspective for the individuals involved in industrial...     

Estimates of dietary exposure of children to artificial food colours in Kuwait

To assess the intake of artificial food colour additives by 5-14-year-old children in the State of Kuwait, a 24-h dietary recall was conducted twice on 3141 male and female Kuwaiti and non-Kuwaiti children from 58 schools. The determination of colour additives in 344 foods items consumed was performed using high-performance liquid chromatography with diode array detector. A comparison with the Food and Agriculture Organization and World Health Organization acceptable daily intakes (ADIs) was undertaken to evaluate the potential risk associated with the consumption of artificial colour additives by children in Kuwait. The results indicated that out of nine permitted colours, four exceeded their ADIs by factors of 2-8: tartrazine, sunset yellow, carmoisine and allura red. Further, follow-up studies to provide insight into potential adverse health effects associated with the high intakes of these artificial colour additives on the test population are warranted.     

Performance of an inverted flat plate solar collector

In this note an analysis of an inverted flat plate solar collector has been presented. Effect of various parameters, namely thickness of the insulation, air conductance between flowing water and top of the bottom insulation, length of the collector and flow velocity of water on the performance of the collector have been studied. Numerical calculations have been made for typical cold day in Delhi, namely 26 January 1980.     

Optical, electrical and structural investigations on Cd1−xZnxSe sintered films for photovoltaic applications

II–VI polycrystalline semiconducting materials have come under increased scrutiny because of their wide use in the cost reduction of devices for photovoltaic applications. Cd_1−xZn_xSe is an important semiconducting alloy because of the tunability of its physical parameters such as band gap and lattice parameters by controlling its stoichiometry. Many more material characteristics of it would be altered and excellently controlled by controlling system composition x.Polycrystalline thin films of Cd_1−xZn_xSe with variable composition (0x1) have been deposited onto ultra-clean glass substrates by sintering process. The optical, structural and electrical transport properties of Cd_1−xZn_xSe thin films have been examined. The optical band gap and optical constants of these films were determined by using double beam spectrophotometer. The DC conductivity and activation energy of the films were measured in vacuum by two-probe technique. The Schottky junction of Cd_1−xZn_xSe with indium was made and the barrier height and ideality factor were determined using current–voltage characteristics. The nature of sample, crystal structure and lattice parameters were determined from X-ray diffraction patterns. The films were polycrystalline in nature having cubic zinc-blende structure over the whole range studied.Sintering is very simple and viable compared to other cost intensive methods. The results of the present investigation will be useful in characterizing the material, Cd_1−xZn_xSe, for its applications in photovoltaics.     

Oligodendroglial precursor cell susceptibility to hypoxia is related to poor ability to cope with reactive oxygen species

Paired helical filaments, one of the major hallmarks of Alzheimer's disease brains at autopsy, consist mainly of aberrantly phosphorylated tau. This aberrant tau phosphorylation can be induced in the human neuroblastoma cell line TR14 by a hyperstimulating mixture, consisting of nerve growth factor (NGF), db-cAMP, gangliosides and sodium butyrate (NaBut) [20,23]. Evidence is presented that exposing these cells to increasing concentrations of NaBut alone in the 0.5-2 mM dose-range is sufficient to induce aberrant tau phosphorylation within 24 h, measured by AT-8 immunocytochemistry and Western blotting. This process is associated with increased morphological differentiation. Furthermore, the aberrant tau phosphorylation is followed by neurotoxicity. This neurotoxicity has features of programmed cell death, such as fragmentation on a DNA agarose gel, fragmented nuclei and chromatin condensation and inhibition by the protein synthesis inhibitor cycloheximide. The mechanism by which NaBut induces these modified tau proteins and neurotoxicity are largely unknown but the data suggest an involvement of cytoskeletal proteins.     

Comparative Evaluation Of Surface Water Availability,Wastewater Reuse And Desalination In Saudi Arabia

ABSRTACT

There is a growing concern in the Kingdom of Saudi Arabia to exploit water resources of acceptable quality to meet demands in domestic, industrial, and agricultural sectors. The agricultural water need, which constitutes approximately 84% of the total demand, was estimated to be 7430 million cubic meters in 1985. The annual domestic and other demands amounted to 1400 million cubic meters for 1985. Various alternative supplies to meet these demands are surface water, renewable groundwater resources, reclaimed wastewater, desalinated water, and non-renewable groundwater. Due to excessive withdrawal of water from deep aquifers, considerable drawdown has recently been noticed.

This paper reviews the existing and future trends in developing surface water resources, reclamation of waste-water from various towns and cities and its use, and the role of desalination plants in the coastal regions of the Arabian Gulf and Red Sea. These alternatives are evaluated and compared in economic terms. Cost-capacity relationships are developed for various alternatives which will be used in developing long-term plans for optimum allocation of available resources in different parts of the Kingdom.     

A Redox‐Based Superoxide Generation System Using Quinone/Quinone Reductase

Superoxide (O₂^.?) generation in biological systems is achieved through some of the most complex enzymatic systems. Of these, only xanthine/xanthine oxidase has been used for in vitro biochemical studies. However, it suffers from limitations such as a lack of suitable heterologous expression system for xanthine oxidase and the irreversible consumption and low solubility of xanthine under physiological conditions. Herein, we report a redox‐based, enzyme‐catalyzed system, in which autoxidation of hydroquinone to quinone via semiquinone results in superoxide generation. Quinone is reduced back to hydroquinone by using the NfsB (oxygen‐insensitive nitroreductase) enzyme of Escherichia coli strain K‐12 and nicotinamide adenine dinucleotide phosphate hydride (NADPH; which is regenerated by using the glucose/glucose dehydrogenase system). This new system relies on quinones that can be recycled and have superior water solubility, as well as enzymes that are heterologously expressed. By using a variety of quinones and reaction conditions, along with a comparison of real‐time fluorescence, menadione has been identified as the optimal substrate for superoxide generation. The new redox‐based system presents a viable alternative for studying the biochemistry of superoxide under different physiological and pathological conditions.     

Improving high‐power properties of PZT ceramics by external DC bias field

This paper concludes that the deterioration of the mechanical quality factor Q_m when operated under high power, can be recovered by externally applying positive DC bias field. Material constants for piezoelectric ceramics are generally characterized under low‐power conditions. However, high‐power properties deviate significantly from the ones measured under low‐power conditions (Q_m degrades by a factor of ~2). DC Bias field helps to recover the properties of the ceramic under high‐power conditions. The DC bias field of 200 V/mm exhibits an almost equivalent “opposite” change rate to the vibration velocity of 0.1 m/s. It is also notable that the piezoelectric loss tan θ’ can be decreased most effectively under positive DC bias field (1.9% per 100 V/mm for the hard PZT and 3.1% per 100 V/mm for the soft PZT), in comparison with the elastic or dielectric losses. This report presents a comprehensive analysis on the low‐ and high‐power piezoelectric properties of hard and soft Lead Zirconate Titanates (PZT's) under externally applied DC bias field in the k₃₁ resonance mode (transverse extensional).