Distributed biological computation: from oscillators,logic gates and switches to a multicellular processor and neural computing applications

Neural Computing and Applications - Ever since its foundational years, synthetic biology has been focused on the implementation of biological computing structures. In the beginning, engineered...     

Reactions of uranium oxysulfide with some nonmetals and metals

Conclusions A study was made, using the optical microscopy and x-ray diffraction techniques, of the reactions of uranium oxysulfide with boron, silicon, lanthanum, and yttrium in the temperature range 1000–1700°C. Boron and silicon cannot be employed as reducing agents in the synthesis of uranium monosulfide from uranium oxysulfide. It was established that in the operation of a reactor UOS present in sulfide fuel is a harmful impurity because it reacts with lanthanides forming in the course of fission.Translated from Poroshkovaya Metallurgiya, No. 10(166), pp. 97–100, October, 1976.The author wishes to thank Professor D. Kolar for helpful discussion. He is also most grateful to the Boris Kidri Fund for financing the work.     

Gelatin-pretreated carbon particles for potential use in lithium ion batteries

Graphite anodes for use in lithium ion batteries were prepared from graphite particles pretreated in a gelatin solution. The content of gelatin in the final anode material was determined from the difference in mass of graphite particles before and after the treatment with gelatin and by thermogravimetric analysis. Forces between a gelatin-coated glass particle and graphite surface were measured in solution using an atomic force microscope. The effect of gelatin content on the characteristics of first charge-discharge cycle is measured and commented in terms of a simple passivation model.     

The investigation of high-temperature strength of SiC based refractories

The Brew-Instron apparatus was used in order to investigate the temperature dependence of bend strength of SiC based refractories in the range from room temperature up to 1400°C. The results obtained show that the strength of the samples strongly depends on the type and amount of bonding phase used (silicate, nitride) as well as on the grain size and the grain size distribution of the SiC phase. Nitride bonded materials are superior to silicate bonded and by decreasing the SiC grain size the high-temperature strength can be markedly increased. The extend of deformation is governed mainly by the SiC grain size, whereas the amount of binder phase does not influence it significantly. The results are discussed with reference to other methods which are used to characterize the performance of the refractories.     

Crack extension and arrest within the particle subjected to tensile thermoelastic stresses in brittle matrix composites

A stress relaxation mechanism which entails circumferential cracking around a spherical particle is presented. In a dispersion-strengthened system, composed of spherical particles of different elastic and fracture properties and a matrix of lower thermal expansion, the location and extent of crack propagation is determined by the relative magnitude of elastic and fracture properties of the matrix and the particulate phase. A simple energy balance criteria is adopted to describe the extent of post-initiation crack propagation and to show the relationship between the initial flaw size and the arrested crack length. The major implications of the analysis are discussed in the light of the reported experimental data.     

Low-temperature synthesis of sinterable SiC powders by carbothermic reduction of colloidal SiO2

-SiC powders were synthesised by carbothermic reduction of carbon-black doped silica gel. The morphological characteristics of the resulting powders depend on the morphology of precursor carbon black as well as the reaction conditions. A model for particle coarsening during carbothermic reduction is presented, suggesting that surface diffusion may be responsible for the formation of polycrystalline aggregates, while at higher reaction temperatures volume diffusion is operative. Processing consisting of decarburization, HF treatment and sedimentation but no milling is required to convert crude reaction products into sinterable powders. After doping with boron and carbon they can be sintered to 98–99% of theoretical density which, in general, is better than or comparable to results obtained with commercial -SiC powders which were also included in the present study.