EXTRACTION OF ACTINIDES BY BIFUNCTIONAL PHOSPHINIC ACID RESIN

ABSTRACT

The extraction of U(VI), Am( III), Pu( IV), Np( IV) and ThIV) by bifunctional phosphinic acid resin of various cross linkages is reported as function of nitric acid concentration. From the comparison of the distribution coefficient values it is suggested that the recovery of these actinide elements from waste solutions as we II as their mutual separations is possible by using phosphinic acid resin.     

HYDROXYL RADICAL MODIFICATION OF FISH MUSCLE PROTEINS

A xanthine oxidase-based system was used to generate hydroxyl free radicals in washed, minced cod muscle. Oxidation of protein was measured by increase in protein carbonyl content; the system used produced approximately 0.1 mol of carbonyl groups per 10⁵ g of protein. This degree of oxidation had only minor effects on the SDS-PAGE patterns of the muscle proteins. The solubility of the proteins was not affected by this amount of oxidation unless they were also subjected to a freeze/thaw cycle. With a freeze/thaw cycle, a highly significant decrease in protein solubility occurred compared to that which took place in a sample not exposed to the free radical system. Lowering the pH from 6.8 or 6.5 to 6.0 or 5.5 had a strong negative impact on protein solubility. Protein oxidation appeared in two phases in washed cod mince, an initial rapid increase followed by a second phase that may have been linked to oxidation of the small amount of lipid in the sample. Comparison of protein carbonyl formation in stored mackerel fillets or mince indicated that the range of oxidation studied in the cod model system was similar to what occurs in stored mackerel muscle postmortem.     

Fractional cell formation in group technology

Group Technology (GT) aims at improving productivity in batch manufacturing. Here components are divided into families and machines into cells such that every component in a part family visits maximum number of machines in the assigned cell with an objective of minimizing inter-cell movement. In situations where too many inter-cell moves exist, fractional cell formation using remainder cells can be used. Here, machines are grouped into GT cells and a remainder cell, which functions like a job shop. Component families are formed such that the components visit the assigned cell and the remainder cell and do not visit other cells. The fractional cell formation problem to minimise inter-cell moves is formulated as a linear integer programming problem. Here, movement between machine cells and remainder cells is not counted as inter-cell moves but movement of components among GT cells is considered as inter-cell movement. The fractional cell formation problem is solved using Simulated Annealing. A heuristic algorithm is developed to solve large sized GT matrices. These have applied to a variety of matrices from GT literature and tested on randomly generated matrices. Computational experiences with the algorithms are presented     

Studies on electroless Ni-P-Cr_2O_3 and Ni-P-SiO_2 composite coatings

本文对化学镀镍及化学镀镍磷基质中SiO2与Cr2O3的共沉积进行了研究。微粒在不断生长的膜层中共沉积引起了新的化学复合镀层的出现,这些复合镀层许多都具有优异的耐磨及耐蚀性能。通过选取镀层合金/复合微粒/金属基体的组分可改进镀层,获得所需的性能,以满足特别的需求。在对这些复合镀层的应用需求正在迫近与增长的同时,其市场正在迅速扩张。本文开发出了一种合适的复合化学镀镍液,并通过维氏硬度法对化学复合镀镍层进行了表征。采用动电位极化及交流阻抗法测定了镀层的Taber耐磨性能及耐蚀性能。采用SEM及XRD对复合镀层的表面形貌进行了分析。     

Physicochemical Changes in Prawns (Machrobrachium rosenbergii) Subjected to Multiple Freeze-Thaw Cycles

Fresh prawns were subjected to five freeze-thaw cycles (–29°C ? 22°C) and associated physicochemical changes in muscle were determined. Shear force to break prawn tails was dependent on prawn size, more on weight (r = 0.75–0.81) than on diameter (r = 0.56–0.66). No change (P > 0.05) in shear force was observed in raw prawns after five freeze-thaw cycles. However, shear force of cooked prawns decreased after three freeze-thaw cycles which coincided with accelerated lipid oxidation in raw prawns. Electrophoretic analysis revealed gradual decreases in myosin, actin, and most other myofibrillar proteins with each successive freeze-thaw cycle. Enthalpy of protein denaturation decreased from 16.6 J/g (fresh) to 13.5 J/g after one freeze-thaw cycle with minor changes thereafter.     

Proteose Peptones and Physical Factors Affect Foaming Properties of Whey Protein Isolate

Effects of peptides and nonprotein components of whey on whey protein isolate (WPI) were studied using a differential pressure method. Decay of WPI foam followed biphasic first-order kinetics, but was affected by solution conditions. WPI foam stability exhibited two pH optima (5.0 and 8.5). Addition of 0.02–0.15M NaCl progressively decreased foaming capacity and foam stability. Addition of 0.01–0.2% proteose-peptones caused a sharp decrease in foam stability, but did not affect WPI foaming capacity. Foam stability was increased by addition of up to 20% lactose. Removal of proteose-peptones should greatly improve foaming properties of whey proteins.     

MASS TRANSFER COEFFICIENTS FOR REACTIVE FLUIDS FLOWING IN CONDUITS WITH SEMI-PERMEABLE WALLS

The advancing front theory is an approximate solution for mass transfer into a reactive fluid when the reaction can be assumed to be very fast. The theory has had considerable use in predicting mass transfer characteristics for reactive fluids flowing in conduits. In this paper, the mass transfer coefficient, in the form of the local, fluid-side Sherwood number, is derived for reactive flow in conduits with semi-permeable walls. The local, fluid-side Sherwood number is given as a function of the Graetz number, the wall Sherwood number, and a dimensionless reaction strength parameter. The limiting cases of both the constant wall concentration boundary condition (Sh_w?∞) and the constant wall flux boundary condition (Sh_w?∞)are investigated. Comparisons of the results with the classical Graetz and Leveque theories give conclusions about the accuracy of the advancing front theory for the worst possible case.     

PREDICTION OF DIFFUSIVITIES FOR ASSOCIATION COMPLEX FORMING ALCOHOL SOLVENT SYSTEMS

Solute's self association and solute-solvent complex formation in alcohol-solvent liquid mixtures can result in large errors in the prediction of diffusivities for such systems by the hitherto proposed generalized correlations. This work reports an attempt to develop a model for predicting diffusivities for alcohol-solvent systems taking into account both the self association and interassociation phenomena and assuming that the former takes place as dimer formation and the latter involves one molecule of solute that is the alcohol and one of the solvent, the non-alcohol component such as unsaturated hydrocarbons, esters ketones etc. It has been observed that an appreciable improvement in the prediction results even if these complex formation phenomena are accounted for in this simplified way and this has been shown for a few selected systems.