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The bio-molecules from various plant components and microbial species have been used as potential agents for the synthesis of silver nanoparticles (AgNPs). In spite of a wide range of bio-molecules assisting in the process, synthesizing stable and widely applicable AgNPs by many researchers still poses a considerable challenge to the researchers. The biological agents for synthesizing AgNPs cover compounds produced naturally in microbes and plants. More than 100 different biological sources for synthesizing AgNPs are reported in the past decade by various authors. Reaction parameters under which the AgNPs were being synthesized hold prominent impact on their size, shape and application. Available published information on AgNPs synthesis, effects of various parameters, characterization techniques, properties and their application are summarised and critically discussed in this review.

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Previous experimental data on mass transfer between particles and fluid in fixed and fluidized beds are reanalyzed and correlating equations are developed for the various situations.

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~Two new glycowithanolides, sitoindoside IX (1) and sitoindoside X (Z), isolated from Withuniu somniferu Dun., were evaluated for their immunomodulatory and CNS effects (anti-stress, memory and learning) in laboratory animals, because the plant extract is used by practitioners of the Indian systems of medicine for similar purposes. The two compounds, in doses of 100-400 & n o u s e , produced statistically significant mobilization and activation of peritoneal macrophages, phagocytosis and increased activity of the lysosomal enzymes secreted by the activated macrophages. Both these compounds (50-200 mg/kg p.0.) also produced significant anti-stress activity in albino mice and rats and augmented learning acquisition and memory retention in both young and old rats. These findings are consistent with the use of W . somniferu, in Ayurveda, to attenuate cerebral function deficits in the geriatric population and to provide non-specific host defence.

To render layered silicates miscible with polymer matrices, one must convert the normally hydrophilic silicate surface to an organophilic one, making the intercalation of polymeric chain between silicate layers possible. This can be done by ion-exchange reactions with cationic surfactants. Sodium montmorillonite (Na-MMT) was modified with several organic cationic surfactants. Organoclays with water soluble surfactants were prepared by the traditional cation exchange reaction. An alternative procedure was used to prepare organoclays with water insoluble salts. The basal spacing and thermal behavior of organoclays were characterized by X-ray diffraction, XRD and Thermogravimetric analysis, TGA respectively

Alumina nanoparticles were developed by the sol−gel method and were used for the removal of Ni(II) ions from aqueous solutions. The nanoparticles were characterized by TEM and XRD. Nanoparticles of alumina were then used for removal of Ni(II) ions from aqueous solutions of nickel. The nanosize of the adsorbent was confirmed by TEM and XRD. Removal (%) was found to be dependent on the initial concentration of nickel, and maximum removal was found to be 96.6% at 25 mg/L Ni(II). The removal increased from 99 to 99.6% by decreasing the initial concentration from 75 to 25 mg/L. Equilibrium time was found to be 120 min. As expected, higher removal was obtained at higher adsorbent dose. The removal was governed by first-order kinetics, and the value of the rate constant of adsorption was found to be 1.83 × 10−2 min−1 at 25 mg/L and 25 °C. The removal was found to be pH dependent, and maximum removal was found to be at pH 8.0. The adsorption process was endothermic in nature. The experimental data fit well the Langmuir and Freundlich isotherms. Constants of the two isotherm equations were determined. Thermodynamic studies for the present process were performed by determining the values of ΔG°, ΔH°, and ΔS° at different temperatures.