Effect of Thermal Aging and Chemical Treatment on Tensile Properties of Coir Fiber

Effect of thermal aging and chemical treatment on the physical properties of coir fiber was investigated. Coir fibers were treated with sodium hydroxide and glutaraldehyde for 2 h. The influence of alkali and aldehyde treatment on tensile strength and elongation at break was studied in detail. Enhancement in tensile strength of coir fiber was observed up to five days of aging at 50°C and further decreased. Thermal cross linking of cellulose present in the fiber may be the reason for the increase in tensile strength and thermal degradation due to the chain scission of cellulose reduced the tensile strength. Sodium-hydroxide-treated samples showed an increase in tensile strength and reduction in elongation at break. The removal of impurities such as waxy and fatty acid residues from the coir fiber by reacting with strong base solution improved the strength of fiber. Cross linking of cellulose with glutaraldehyde in the fiber reduced the elasticity and enhances the strength of the material. Scanning electron microscopy was employed to analyze the change in surface morphology upon chemical treatment. Improvement in the tensile strength suggests that NaOH and glutaraldehyde can be effectively used to modify coir fiber with excellent physical properties.     

A model of the structure of the receptor apparatus of HIV target cells (1)

A model is proposed and well based of structure of the receptor apparatus of interacting HIV target cells: Langerhans cells (LC) and helper cells (HC)--designed to explain feasibility of realizing a double activation signal, together with some features of immune pathogenesis of HIV-infection (morphofunctional abnormalities in certain subpopulations of the immune system such as HC, suppressor cells, killer cells, natural killers, lymph cells, macrophages, LC), as well as immunogenetic predisposition to AIDS.     

Kinetics, mathematical modeling, and optimization of the oxidative coupling of methane over a LiMnW/SiO2 catalyst

A phenomenological kinetic model is developed, and the numerical values of the kinetic parameters of the oxidative coupling of methane that is catalyzed by a new LiMnW/SiO₂ composite material are determined. The mathematical modeling of the process is performed, and the optimal conditions and approaches to the apparatus-technological design of the process are determined.