Study on electrical transport and photoconductivity in iodine-doped cellulose fibers

The electrical transport and photoconductivity of pure and iodine-doped cellulose fibers have been studied. The studies were conducted in the temperature range 293–363 K, while the electric field was varied over the range 1–100 V cm⁻¹. The conductivity of the iodine-doped cellulose fibers shows significant enhancement by more than four orders of magnitude as compared to undoped samples. The analysis reveals that the electrical conduction follows Ohm’s law for iodine-doped samples, while for the undoped samples the bulk-limited Pool–Frenkel conduction mechanism is likely to dominate for the steady state current. Especially, the clear photoconduction response at UV and visible region indicates that photoconduction is essential due to band-to-band electron–hole pair’s generation and that doped CF is a good conductor of photogenerated carriers.     

Tax impact on multi-stage mean-variance portfolio allocation

We investigate the sensitivity to tax change of multi‐stage portfolio allocation over a discrete time investment horizon. Special taxation rules within wrappers grouped a number of risky assets are integrated with multi‐stage linear or quadratic stochastic programming in the mean‐variance framework. The uncertainty on the returns of assets is specified as a scenario tree generated by a simulation‐based approach. We adjust different values on capital gains tax under different asset bounds and risk levels. The tax impact in the yearly reallocation of the investments for a typical case with an annual fixed withdrawal that utilizes completely the option of taper relief is also explored. Our computational results show that taxes, combined with other effects such as risk and investment upper bounds, have a significant performance impact on portfolio allocation as well as diversification over wrappers. Yet, investment strategies can be made robust to changes in taxation.     

Copolymerization of acrylonitrile,methyl acrylate,and itaconic acid in thiocyanate solutions in the presence of hydrolyzed nitron fibre waste

Conclusions -- The kinetics of the copolymerization process of AN, MA, and IA in the presence of hydrolyzed Nitron fibre characterized by various degrees of hydrolysis has been studied. It has been found that introducing H-PAN into the reaction mixture leads to an increase in degree of conversion in the copolymerization process and to an increase in molecular weight of the copolymer synthesized.-- Fibre has been spun from the products of joint copolymerization of AN, MA, and IA in the presence of H-PAN with various concentrations of these in the solution and various SEC values. Introducing up to 5% by wt. of an H-PAN with an SEC not over 0.2 meq/g into the reaction mixture aids in obtaining fibres with satisfactory properties and opens up the possibility of still another way of solving the question of regenerating wet Nitron fibre wastes.Translated from Khimicheskie Volokna, No. 4, pp. 17–19, July–August, 1991.     

Development and introduction of wire for engine valve springs in VAZ

Valve springs (inner and outer) are critical parts of a car and therefore should meet stringent requirements with respect to their endurance and elastic properties. Results of work on introducing wire for valve springs of steel 70KhFA-Sh instead of Oteva-60 (68CrV2) are described.     

Performance of refrigerating plant with efficient heat exchangers

An installation diagram is presented for investigation of the performance of a refrigerating plant with both smooth and rolled tubes having annular eddy generators. Results are presented for comparative tests with the traditional coolant R12 and an ecologically pure coolant developed by the Tashkent State Technical University — a mixture of propane/isobutane/n-butane (R290/R600a/R600) with a molar concentration of 40/30/30%, respectively — used as the effective body. Exergetic efficiencies of the plant are calculated. It is demonstrated that replacement of the coolant has virtually no effect on the thermodynamic parameters of the plant.