Poly(Urethane)-Crosslinked Poly(HEMA) Hydrogels

Abstract

Hydrogels have been prepared from 2-hydroxyethyl methacrylate polymerized in the presence of isocyanate-terminated poly(ethylene glycol) (PEG) crosslinking agents. PEGS of molecular weights 200, 400, and 1000 were investigated. The crosslinked nature of the hydrogels was demonstrated by their insolubility in solvents which normally dissolve poly(HEMA). Hexamethylene diisocyanate (HDI) was mainly used as the isocyanate. The molecular weight of the PEG and the crosslinker content significantly influenced the equilibrium water sorption and mechanical properties of the saturated networks. It was observed that as the molecular weight of the PEG increased, the water sorption increased and the nominal modulus decreased. However, for higher levels of cross-linker, water sorption decreased and modulus increased at low molecular weight PEG; for PEG 1000, water absorption increased as crosslinker content increased. These results are explained by the competing effects of flexibility, crosslink density, and hydrophobicity contributed by the various constituents of the hydrogels.     

Electron transfer reactions associated with ethyl viologen-β-cyclodextrin complexation: equilibrium and kinetic aspects

Formation of the complex of ethyl viologen in its cationic (Ev^+?) and neutral (Ev^°) forms with β-cyclodextrin (β-CD) was investigated by means of voltammetric technique in buffer solution of pH 7.00. The number of βCD (n or m) per viologen species (Ev^+?) or (Ev^°), bonding equilibrium constants as well as bonding rate constants was calculated. The calculated values of $K_{\text{eq}}^{(1)}$ and $K_{\text{eq}}^{ ( 2)}$ (pertaining to the bonding of Ev^+? and Ev^° with βCD) are 13.6 M^–n and 2.1 × 10³ M^?m , respectively, whereas the calculated values of n and m are 0.54 and 1.25, respectively. The bimolecular rate constant for the Ev^°?βCD inclusion complex formation is 3.03 × 10³ M^?1s^?1. These results are supported by the simulation of the experimental cyclic voltammograms. This study also highlights the significance of the proposed electrochemical method as compared to earlier studies on viologen-Cyclodextrin systems.     

Selenium Alleviates the Adverse Effect of Drought in Oilseed Crops Camelina (Camelina sativa L.) and Canola (Brassica napus L.)

Drought poses a serious threat to oilseed crops by lowering yield and crop failures under prolonged spells. A multi-year field investigation was conducted to enhance the drought tolerance in four genotypes of Camelina and canola by selenium (Se) application. The principal aim of the research was to optimize the crop yield by eliciting the physio-biochemical attributes by alleviating the adverse effects of drought stress. Both crops were cultivated under control (normal irrigation) and drought stress (skipping irrigation at stages i.e., vegetative and reproductive) conditions. Four different treatments of Se viz., seed priming with Se (75 μM), foliar application of Se (7.06 μM), foliar application of Se + Seed priming with Se (7.06 μM and 75 μM, respectively) and control (without Se), were implemented at the vegetative and reproductive stages of both crops. Sodium selenite (Na₂SeO₃), an inorganic compound was used as Se sources for both seed priming and foliar application. Data regarding physiochemical, antioxidants, and yield components were recorded as response variables at crop maturity. Results indicated that WP, OP, TP, proline, TSS, TFAA, TPr, TS, total chlorophyll contents, osmoprotectant (GB, anthocyanin, TPC, and flavonoids), antioxidants (APX, SOD, POD, and CAT), and yield components (number of branches per plant, thousand seed weight, seed, and biological yields were significantly improved by foliar Se + priming Se in both crops under drought stress. Moreover, this treatment was also helpful in boosting yield attributes under irrigated (non-stress) conditions. Camelina genotypes responded better to Se application as seed priming and foliar spray than canola for both years. It has concluded that Se application (either foliar or priming) can potentially alleviate adverse effects of drought stress in camelina and canola by eliciting various physio-biochemicals attributes under drought stress. Furthermore, Se application was also helpful for crop health under irrigated condition.     

Study of the interfacial charge transfer in bismuth vanadate/reduce graphene oxide (BiVO4/rGO) composite and evaluation of its photocatalytic activity

Research on Chemical Intermediates - We prepared unique BiVO4/reduce graphene oxide (BiVO4/rGO) nanocomposite with enhanced photocatalytic ability by hydrothermal method applying...     

Magnetic,Electrical and Thermal Studies of Polypyrrole-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> Nanocomposites

This research paper comprises of the synthesis of polypyrrole (PPy)-Fe₂O₃ nanocomposites by employing the in situ chemical oxidative polymerization method. The concentration of the filler material was adjusted between 10–50 wt % of PPy. The synthesized nanocomposites were characterized by using X-ray diffraction (XRD). Magnetic analysis and DC electrical conductivity of the samples were carried out using vibrating sample magnetometer (VSM) and two probe DC conductivity method, point towards magnetically active and electrically conductive samples. The magnetic parameters under applied magnetic field demonstrated that the values of coercivity (H _c ), saturation magnetization (M _s ) and remanence (M _r ) can be tailored by carefully controlling the amount of dopant material into the nanocomposites indicating their suitability for controllable switching devices and microwave absorption applications. The DC electrical conductivity showed an increase up to 20 wt % of filler material and thereafter a decrease in the conductivity of nanocomposites with increase in filler content is observed. Thermogravimetric analysis (TGA) showed an increase in thermal stability with an increase in ferrite content in nanocomposites.     

A Comprehensive Review on Therapeutic Perspectives of Phytosterols in Insulin Resistance: A Mechanistic Approach

Natural products in the form of functional foods have become increasingly popular due to their protective effects against life-threatening diseases, low risk of adverse effects, affordability, and accessibility. Plant components such as phytosterol, in particular, have drawn a lot of press recently due to a link between their consumption and a modest incidence of global problems, such as Type 2 Diabetes mellitus (T2DM), cancer, and cardiovascular disease. In the management of diet-related metabolic diseases, such as T2DM and cardiovascular disorders, these plant-based functional foods and nutritional supplements have unquestionably led the market in terms of cost-effectiveness, therapeutic efficacy, and safety. Diabetes mellitus is a metabolic disorder categoriszed by high blood sugar and insulin resistance, which influence major metabolic organs, such as the liver, adipose tissue, and skeletal muscle. These chronic hyperglycemia fallouts result in decreased glucose consumption by body cells, increased fat mobilisation from fat storage cells, and protein depletion in human tissues, keeping the tissues in a state of crisis. In addition, functional foods such as phytosterols improve the body’s healing process from these crises by promoting a proper physiological metabolism and cellular activities. They are plant-derived steroid molecules having structure and function similar to cholesterol, which is found in vegetables, grains, nuts, olive oil, wood pulp, legumes, cereals, and leaves, and are abundant in nature, along with phytosterol derivatives. The most copious phytosterols seen in the human diet are sitosterol, stigmasterol, and campesterol, which can be found in free form, as fatty acid/cinnamic acid esters or as glycosides processed by pancreatic enzymes. Accumulating evidence reveals that phytosterols and diets enriched with them can control glucose and lipid metabolism, as well as insulin resistance. Despite this, few studies on the advantages of sterol control in diabetes care have been published. As a basis, the primary objective of this review is to convey extensive updated information on the possibility of managing diabetes and associated complications with sterol-rich foods in molecular aspects.     

Outdoor ground impedance models

Many models for the acoustical properties of rigid-porous media require knowledge of parameter values that are not available for outdoor ground surfaces. The relationship used between tortuosity and porosity for stacked spheres results in five characteristic impedance models that require not more than two adjustable parameters. These models and hard-backed-layer versions are considered further through numerical fitting of 42 short range level difference spectra measured over various ground surfaces. For all but eight sites, slit-pore, phenomenological and variable porosity models yield lower fitting errors than those given by the widely used one-parameter semi-empirical model. Data for 12 of 26 grassland sites and for three beech wood sites are fitted better by hard-backed-layer models. Parameter values obtained by fitting slit-pore and phenomenological models to data for relatively low flow resistivity grounds, such as forest floors, porous asphalt, and gravel, are consistent with values that have been obtained non-acoustically. Three impedance models yield reasonable fits to a narrow band excess attenuation spectrum measured at short range over railway ballast but, if extended reaction is taken into account, the hard-backed-layer version of the slit-pore model gives the most reasonable parameter values.