Evaluation of relative nutritive value in cultivars of triticale with shrivelled grain characteristics,using Aspergillus flavus

Aspergillus flavus Link ex Fr., was used to evaluate the Relative Nutritive Value (RNV) in a set of triticale cultivars having shrivelled grain characteristics. The protein content in these samples ranged from 11.8 to 24.0%. The milled material was tested at 3 mg nitrogen level. Biomass of the fungus was measured as the total dry weight of the mycelium produced after 72 h of shaking and taken as the index of Relative Nutritive Value. The fungal biomass was negatively correlated with protein content and dye binding capacity while a positive correlation existed with protein index. With the use of glucose as an extra energy source, the basic pattern of response remained the same but the magnitude of correlation decreased.     

SELF-DIFFUSION IN POTENTIALS OF MEAN FORCE IN WEAKLY- AND STRONGLY-INTERACTING DISPERSIONS

Studies of interactions in dispersions have traditionally focused on the stability and transport properties of such systems at extreme dilution, that is, at concentrations for which colloidal and hydrodynamic interactions are significant between at most two particles at a given time. In practice, however, dispersions of interest often do not satisfy this restriction, and, consequently, many-body colloidal interactions and hydrodynamic coupling have important roles in the observed macroscopic behavior. This paper presents an analysis of the effects of many-body interactions on the self-diffusion coefficient in interacting dispersions. Self-diffusion coefficients have been determined for dilute-gas dispersions and for Yukawa dispersions interacting through appropriate potentials of mean force. It is shown that the diffusion coefficients change negligibly with attraction for typical magnitudes of the Hamaker constant in an otherwise repulsion-dominated (i.e., stable) dispersion. The results show that, for thin electrical double layers, dilute dispersions can be approximated by hard-sphere dispersions, even for large values of surface potentials. However, for thick double layers (i.e., thickness comparable to particle radius), while the short-time diffusion coefficient is affected only negligibly, the long-time coefficient can decrease considerably because of the 'memory' effects—even for moderate or low values of the surface potentials. Corresponding results are presented for both dilute-gas dispersions and dispersions with significant local structures. The long-time diffusion coefficients in the latter are effectively linear in volume fraction (up to about 0.2)for thin double layers and are given with reasonable accuracy by the dilute-gas approximation.     

The Ga−Sb (Gallium-Antimony) system

R. C. Sharma was Visiting Assistant Professor (1984–1986)     

Prediction of rate-independent constitutive behavior of Pb-free solders based on first principles

This paper presents a methodology for the theoretical estimation of rate-independent plastic constitutive properties of Pb-free solders using three approaches. The first approach is based on a nonlinear effective medium theory (NEMT) that is scale independent. The second approach is based on the micromechanics and physics of plastic slip in heterogeneous alloys (henceforth called the physical model). This approach explicitly includes microstructural features such as grain size, particle size etc. The third approach is a combination of NEMT and the physical model. Our estimates involve no adjustable calibration parameters and are based on first principles and constituent properties. Parametric studies are conducted to show that the physical model is more effective for small particles sizes (nanoscale <100 nm), small particle spacing (/spl sim/ nm range) and low volume fractions (<2.5%); while NEMT performs well for large volume fractions (>5%), large particle sizes (micron size) and large particle spacing (micron scale). The proposed hybrid approach, however, appears to be valid for a wider range of particle sizes and volume fractions. Limited comparison with experimental data is also made and implications of our work in the economical design of novel Pb-free solders is discussed.     

Corrosion of bio implants

Chemical stability, mechanical behaviour and biocompatibility in body fluids and tissues are the basic requirements for successful application of implant materials in bone fractures and replacements. Corrosion is one of the major processes affecting the life and service of orthopaedic devices made of metals and alloys used as implants in the body. Among the metals and alloys known, stainless steels (SS), Co-Cr alloys and titanium and its alloys are the most widely used for the making of biodevices for extended life in human body. Incidences of failure of stainless steel implant devices reveal the occurrence of significant localised corroding viz., pitting and crevice corrosion. Titanium forms a stable TiO₂ film which can release titanium particles under wear into the body environment. To reduce corrosion and achieve better biocompatibility, bulk alloying of stainless steels with titanium and nitrogen, surface alloying by ion implantation of stainless steels and titanium and its alloys, and surface modification of stainless steel with bioceramic coatings are considered potential methods for improving the performance of orthopaedic devices. This review discusses these issues in depth and examines emerging directions.     

Condensation polymers from natural oils

Innovative technologies and competitive industrial products are reducing the dependence on petrochemicals for the production of polymers. Increasing concerns about the deteriorating environment caused by conventional polymers have directed worldwide research toward renewable resources. Vegetable oils are one of the most readily available alternative renewable resources. The functional groups present in natural oils can be activated for condensation polymerization. Accordingly, various types of useful condensation polymers, such as polyurethanes, polyesters and polyethers, are being produced by this route. The incorporation of natural oils into the polymer chain allows tailoring the properties of polyurethane products, for their widespread applications.