Thermogravimetry of Lithium Spinel Ferrites

The material-loss behavior of spinel ferrites on heat treatment was characterized by thermogravimetry. Most of the work was done on the system LiFeO₂-Fe₂O₃, where both Li and O₂ loss were considered. The weight-loss behavior of Ni and Zn ferrites was studied for comparison.     

Catalytic Dimerization of Alkyl Acrylates∗

The review deals with the chemistry of dimerization of acrylic esters in the presence of various catalysts. The article covers literature from 1963 through early 1995. The dimerization reactions are divided into three categories depending on the type of catalyst used, namely, phosphine-catalyzed, metal-catalyzed, and miscellaneous catalysts. Phosphine catalyzed dimerization leads to branched or head—tail dimers. Metal catalyzed dimerization deals with the reactions that take place in the coordination sphere of the transition metals (Ni, Pd, Ru, and Rh) complexes and are aimed at linear or tail—tail dimers. The tail—tail dimers, dialkyl hexenedioates, have a commercial potential as precursors of adipic acid, which is a raw material in the manufacture of nylon-6,6. Various strategies involved in designing the transition metal catalysts for tail—tail dimerization are highlighted. A miscellaneous catalyst section deals with systems that are not covered under the above two categories. It describes catalyst systems comprised of organic and/or inorganic compounds leading to head—tail or tail—tail dimers. The hydrodimerization reactions, which directly give dialkyl adipate from acrylic ester, are discussed separately. The mechanisms of the important dimerization reactions are outlined at appropriate places.

     

Isothermal Crack Healing and Strength Recovery in UO2 Subjected to Varying Degrees of Thermal Shock

Isothermal crack healing and strength recovery were investigated in UO₂ pellets subjected to varying degrees of thermal shock by water quenching. It is shown, as was speculated in an earlier paper, that crack density and/or crack width in the specimen strongly influence the subsequent healing behavior. Experimental data were used to demonstrate that, under the present thermal shock conditions, the time required for complete healing increased exponentially with the number of cracks/unit length of the specimen.     

ROLE OF CARROT ON SHELF STABILITY OF DAIRY DESSERT (RASOGOLLA) DURING REFRIGERATED STORAGE

ABSTRACT

Carotene‐enriched carrots (Daucus carota L. var. Chantenay) were evaluated for their inhibitory effects on acidity development and lipid oxidation in rasogolla during refrigerated storage. Rasogolla is mashed fresh cheese or cottage cheese boiled in rounded shape in concentrated sugar syrup. Six types of rasogolla samples containing carrot paste at 0, 10, 20, 30, 40 and 50% were prepared and stored in closed container at refrigerated condition for 20 days. Chemical changes were measured for acidity of syrup, pH of syrup, free fatty acid content and absorptivity of rasogolla samples, and sensory evaluation of rasogolla samples at days 0, 5, 10, 15 and 20 of storage. The carrot pastes showed significant protection against lipid oxidation, acidity development and sensory quality maintenance in rasogolla. Higher levels of carrot pastes were more effective to increase shelf stability in rasogolla at different tested storage times. However, after day 10 of storage, carrot concentration showed negative result, i.e., enhancement of rate of lipid oxidation of rasogolla samples and its syrups along with visual color destruction. Also, excess quantity of carrot in rasogolla reduces the overall acceptance by the consumer. According to the overall result of shelf stability, it could be suggested that carrot concentration up to 30% should be used in rasogolla for long duration of storage, i.e., above 10 days.

PRACTICAL APPLICATIONS

Traditional dairy products such as Rasogolla are important, well balanced food, which contribute a number of nutrients in relation to our need for good nutrition and health. Rasogollas' projected demand is 6000 tonnes in 2009 ( Karunanithy et al. 2007 ). Carrot is a good source of carotene specially beta‐carotene and serve as a good source of natural antioxidant. Fortification of carrot in dairy product serves as functional or health food for people of all age group. It also imparts a safe and attractive color to the dairy product. Besides, it is also cost effective for the dairy industry, because carrot is much cheaper than milk or channa (a dairy product analogous to cottage cheese). Study on the role of carrot on shelf stability of rasogolla under refrigerated storage is an attempt to establish this new product in the dairy industry.

     

Complexity of the diagnosability problem for a general model of diagnosable systems

The complexity of the diagnosability problem for a self-diagnosable system is analysed in this paper. The most commonly studied model (Preparata et al. 1967) for a diagnosable system has been analysed in the literature and a polynomial time algorithm for testing its diagnosability is known. This paper analyses a more general model of the diagnosable system and finds the diagnosability problem to be NP-hard. In this model, each unit is tested by several tests and each test is carried out jointly by several other units of the system as opposed to each test being carried out by a single unit as modelled by Preparata et al. (1967).     

Factors Affecting Antifungal Activity of Onion Extractives Against Aflatoxin-Producing Fungi

The processing factors, that could affect the inhibitory activity of onion extractives against the spores of Aspergillus parasiticus have been evaluated. The lachrymatory factor (thiopropanal-S-oxide) had maximal inhibitory activity. The survival of A. parasiticus spores depended upon the inhibitor concentration and the time of exposure of the spores to the onion inhibitors. Germinated spores showed more susceptibility to the inhibitors. The inhibitory effect of onion compounds was lost by heating, freeze-drying, dehydration, aeration and agitation, and prolonged storage.