Microwave absorbing properties of a thermally reduced graphene oxide/nitrile butadiene rubber composite

Reduced graphene oxide (RGO) with a layered and porous structure was synthesized by thermal exfoliation of graphite oxide. Synthesized RGO is very light weight and flaky. The formation of RGO was studied using Fourier transform infrared and Raman spectroscopies, X-ray diffraction and scanning electron microscopy. Composites were prepared by dispersing 2%, 4% and 10% by weight of the synthesized RGO into nitrile butadiene rubber (NBR) matrix. Microwave absorption properties of RGO/NBR composites were investigated by measuring their complex permittivity and permeability by using waveguide method. Simulation studies show that 10 wt.% of graphene oxide in NBR matrix exhibits high values of reflection loss (>10 dB) over a wide frequency range 7.5–12 GHz and maximum loss is 57 dB at 9.6 GHz at a thickness of 3 mm.     

Hypocholesterolemic effects of low calorie structured lipids on rats and rabbits fed on normal and atherogenic diet

The hypocholesterolemic effects of two low calorie structured lipids (SL1 and SL2) containing essential fatty acids, prepared by lipase catalysed interesterification of ethyl behenate respectively with sunflower and soybean oils were studied in rats and rabbits. The feeding experiment conducted on rats as well as rabbits, fed on normal and atherogenic diet containing 10% of SL1 and SL2 (experimental) and sunflower oil (control) indicated no adverse effects on growth and food intake. However, the structured lipids beneficially lowered serum and liver lipids, particularly cholesterol, LDL cholesterol, triglycerides and also maintains the essential fatty acid status in serum and liver. The lipid deposition observed in the arteries of rabbits fed on atherogenic diets was significantly reduced when structured lipids were included in the diet. These observations coincided with reduced levels of serum cholesterol particularly LDL cholesterol observed in experimental groups. Therefore the structured lipids, designed to have low calorific value also beneficially lower serum lipids and lipid deposition in animals fed on atherogenic diets.     

Radiative transfer modeling of filter-based measurements of light absorption by particles: Importance of particle size dependent penetration depth

We present new physical models to interpret the response characteristics of filter-based measurements of aerosol light absorption. They were motivated by a recently found particle size dependence of a systematic bias in absorption measurements that cannot be interpreted by any models reported thus far. A theory of particle filtration by fibrous filter is applied to reproduce the penetration depth of particles into a filter matrix, and the light transmissivity of the matrix is calculated by the use of radiative transfer theory for plane-parallel layers. Optical properties of individual layers are calculated from microphysical properties and the number density of filter fibers and deposited particles. The size-dependent systematic bias in absorption measurement is successfully explained by the particle size dependence of penetration depth into a filter matrix. In practice the physical models developed here are useful for selecting operating conditions and filter matrices for instruments with fewer systematic biases.     

Fat and fatty acids of Indian edible mushrooms

Twenty-three species of naturally grown and collected mushroom fruiting bodies, from different geographic locations of India, were analysed for their total fat and fatty acid contents. On a dry weight basis, the mushroom species were found to contain 0.6–4.7% total fat. The mushroom species were high in unsaturated fatty acids (52–87%), compared to saturated fatty acids. Oleic acid was the major monounsaturated fatty acid in all the species studied, while linoleic acid was the major polyunsaturated fatty acid. Linolenic acid was in significant quantity in Hydnum repandum and Macrolepiota procera. Linoleic:oleic acid ratios of the mushroom species varied considerably (0.48–10.58).     

Dielectric characterization of fiber- and nanofiller-reinforced polymeric materials

This review provides an in-depth analysis of the electrical responses and relaxation behaviors of various polymeric materials including fiber-reinforced polymer composites, polymer nanocomposites (PNC), and nanofiller-reinforced polymeric films and coatings using dielectric spectroscopy (DS). The underlying theory of DS, corresponding instrumentation, various dielectric parameters, relevant equations, interpretations, and polarization mechanisms are thoroughly explored. The impact of synthetic and natural fibers and a diverse range of nanofillers on the dielectric responses and relaxation mechanisms of fiber-reinforced composites, and PNC and films, respectively, are also examined. For each summarized article, we provide an overview of the composite or film preparation, followed by concise explanations of the dielectric behaviors under diverse conditions, including variations in temperature, frequency, moisture levels, fiber/filler ratios, and chemical treatment. In essence, this review contributes to a nuanced understanding of the intricate relationship between material structure, properties, and performance via DS data interpretation across a spectrum of scenarios.     

Speech to speech interaction system using Multimedia Tools and Partially Observable Markov Decision Process for visually impaired students

Multimedia Tools and Applications - In general, visually impaired students need of another person’s to teach them with the help of computers and book. However, a number of students are not...     

Optimisation of lipase-catalysed interesterification reaction for modulating rheological and heat transfer properties of frying oil

The present work reports the optimisation of enzyme interesterification reaction of rice bran oil (RBO) and refined, bleached, deodorized, palm olein (RBDPO) blend using immobilized 1,3-specific lipase, to improve the kinematic viscosity and heat transfer coefficient of oil, important for characterising heat transfer during the frying process. Four variables, namely RBO (20–80%) in RBO–RBDPO blend, reaction temperature (25–65 °C), enzyme concentration (1–13%, w/w) and reaction time (1–13 h) were selected and optimised using response surface methodology (RSM) coupled with central composite rotatable design (CCRD). The optimisation results predicted that optimum reaction conditions for preparing enzyme interesterified oil, having minimum kinematic viscosity (2.63 × 10⁻⁶ m² s⁻¹) and maximum heat transfer coefficient (262.0 Wm⁻² °C⁻¹) were at 62% RBO, temperature 65 °C, enzyme concentration 10% (w/w) and time 6.4 h. The predicted values were validated experimentally and corroborated with DSC melting profile and triacylglycerol molecular species data. This investigation could help snack food industries to develop suitable oils for frying operations.     

Cost analysis of a two-unit electronic parallel redundant system with overloading effect

A two-unit parallel redundant repairable electronic system with exponential failure-time distribution and overloading effect is considered. The system is to be in any of the three states: good, degraded and failed. One repair facility is available when the system is either in degraded or failed state. The repair for the system in any state follows general distribution. To make the system more applicable to practical life problems, time dependent probabilities have been evaluated so as to forecast the expected profit and operational availability of the system at any time. Using supplementary variable technique, Laplace transforms of various state probabilities have been evaluated. Making use of Abel's theorem, various time independent probabilities have been computed. Also the overloading effect for the expected profit on the operational availability of the complex system has been studied.     

Interaction of curcumin with human serum albumin—A spectroscopic study

Curcumin (diferuloyl methane) has a wide range of physiological and pharmacological actions. Curcumin interaction with human serum albumin (HSA) has been followed by fluorescence quenching and circular dichroism (CD) measurements. Based on fluorescence measurements, the equilibrium constant for the interaction is 2.0±0.2×10⁵M⁻¹. Binding of curcumin to HSA induces an extrinsic CD band in the visible region. From the induced CD band measurements, the equilibrium constant has a value of 2.1±0.3×10⁴M⁻¹. Thus, HSA has two kinds of affinity sites for curcumin, one with high affinity and the other with lower affinity. Job’s plot indicated a binding stoichiometry of 1∶1 for the high-affinity site. The equilibrium constant was invariant with temperature in the range of 15 to 45°C, suggesting the role of hydrophobic interactions in the binding of curcumin to HSA. Curcumin does not change the conformation of the HSA molecule. These measurements have implications in the understanding of the curcumin transport under physiological conditions.     

Innovative Disulfide Esters of Dithiocarbamic Acid as Women‐Controlled Contraceptive Microbicides: A Bioisosterism Approach

In an ongoing effort to discover an effective, topical, dual‐function, non‐surfactant contraceptive vaginal microbicide, a novel series of 2,2′‐disulfanediylbis(3‐(substituted‐1‐yl)propane‐2,1‐diyl) disubstituted‐1‐carbodithioates were designed by using a bioisosterism approach. Thirty‐three compounds were synthesized, and interestingly, most demonstrated multiple activities: they were found to be spermicidal at a minimal effective concentration of 1–0.001 %, trichomonacidal against drug‐susceptible and resistant Trichomonas strains at minimal inhibitory concentration (MIC) ranges of 10.81–377.64 and 10.81–754.14 μM , respectively, and fungicidal at MIC 7.93–86.50 μM . These compounds were also found to be non‐cytotoxic to human cervical (HeLa) epithelial cells and vaginal microflora (Lactobacilli) in vitro. The most promising compound, 2,2′‐disulfanediylbis(3‐(pyrrolidin‐1‐yl)propane‐2,1‐diyl)dipyrrolidine‐1‐carbodithioate ( 5 ), exhibited spermicidal activity 15‐fold higher than that of the marketed spermicide Nonoxynol‐9 (N‐9) and also demonstrated microbicidal potency. To identify common structural features required for spermicidal activity, a 3D‐QSAR analysis was carried out, as well as in vivo efficacy studies and fluorescent labeling studies to determine the biological targets of compound 5 .