Thermal and Volume Effects at Deformation of Thermoplastics and Their Glass Fiber-Reinforced Composites

Parallel measurements have been made of stresses, specific volume, and temperature of PC samples in the process of uniaxial tension. This information made it possible to establish the borders of different regions of a deformation curve. It has been established that the start of microplastic deformations corresponds to maximum value of volume increase and minimum value of temperature change. It has been shown that the tensile yield point corresponds to sharp increase of temperature and Δ V/V ₀ = 0. Experimental methods of determining deformation limits of durability of glass fiber-reinforced thermoplasts have been developed.     

On the response of MMC laminated plates to non-uniform temperature loading: the effect of temperature-dependent material properties

Thermal response of antisymmetrically laminated metal matrix composite (MMC) plates subjected to non-uniform temperature field is analysed. Temperature dependence of both elastic and viscoplastic properties of the metallic matrix is taken into account; this suggests that a non-uniformly heated plate should be considered as a non-homogeneous structure. A micro-to-macro approach is employed to establish the instantaneous thermo-inelastic constitutive law at each point of the plate and to perform the structural analysis.

Results are presented for simply-supported and clamped graphitealuminium plates. The effects of boundary conditions, lamination angle, length-to-thickness ratio and different types of spatial temperature distributions are illustrated. Comparisons with the results obtained using an approach that treats the effect of temperature-dependent material properties in a simplified manner are shown. Comparisons with the corresponding elastic solutions (which neglect the inelastic effects in the metallic matrix) are given.     

Production of H2 for fuel cell applications: methanol steam reforming with sufficiently thorough cleaning of H2 from CO impurity

Methanol steam reforming (MSR) and preferential CO oxidation (PROX) were studied with the view of improving the generation of H₂-rich gases. In MSR, conventional catalysts of methanol synthesis were tested, various Cu-based catalysts were prepared and studied. A theoretic kinetic model (based on the reaction mechanism established using independent methods [1]) is developed and checked out. PROX was studied over various Ru/Al₂O₃ catalysts using a flow “quasi-adiabatic” reactor. On-line recording of gas temperature in the catalyst bed and CO residual concentration at varied reaction conditions allowed to observe ignition and extinction of the catalyst surface and the transition states of the process. It is shown that in the ignition mode a sharp decrease in CO residual concentration can be achieved. The combination of proposed catalyst and the control of the macrokinetic regime of PROX allows high degree of CO removal from gaseous mixtures produced by MSR. Residual CO content in a H₂-rich gaseous mixture can be lowered to < 15 ppm at GHSV∼100 m³/(kg cat)/h and O₂/CO ratio of 1. Obtained data show the possibility of designing a high-throughput set-up for generation of H₂-rich gases from methanol with one-step cleaning from the CO impurity.     

Catabolism of Hydroxyproline in Vertebrates: Physiology,Evolution, Genetic Diseases and New siRNA Approach for Treatment

Hydroxyproline is one of the most prevalent amino acids in animal proteins. It is not a genetically encoded amino acid, but, rather, it is produced by the post-translational modification of proline in collagen, and a few other proteins, by prolyl hydroxylase enzymes. Although this post-translational modification occurs in a limited number of proteins, its biological significance cannot be overestimated. Considering that hydroxyproline cannot be re-incorporated into pro-collagen during translation, it should be catabolized following protein degradation. A cascade of reactions leads to production of two deleterious intermediates: glyoxylate and hydrogen peroxide, which need to be immediately converted. As a result, the enzymes involved in hydroxyproline catabolism are located in specific compartments: mitochondria and peroxisomes. The particular distribution of catabolic enzymes in these compartments, in different species, depends on their dietary habits. Disturbances in hydroxyproline catabolism, due to genetic aberrations, may lead to a severe disease (primary hyperoxaluria), which often impairs kidney function. The basis of this condition is accumulation of glyoxylate and its conversion to oxalate. Since calcium oxalate is insoluble, children with this rare inherited disorder suffer from progressive kidney damage. This condition has been nearly incurable until recently, as significant advances in substrate reduction therapy using small interference RNA led to a breakthrough in primary hyperoxaluria type 1 treatment.     

Hierarchical parallel search for markov control with enhanced selector

A new method of hierarchical parallel search is proposed for dealing with Markov planning/control processes in systems with uncertain information. It is based on a new concept of analyzing alternative with uncertain cost evaluation. Under definite conditions, instead of making an immediate choice based on expectation of cost at each step of the search, it is recommended to postpone the final decision until information is improved, and the uncertainty is reduced. In addition to elementary alternatives, their combinations are also considered for possible pursuit. The best set of rough elementary solutions is to be determined at the upper of two adjacent planning/control levels, then all elementary alternatives of this set as well as their combinations, are being pursued at the lower level with a higher resolution of information, while evaluation of the remaining cost for each of the alternatives, is being constantly improved due to the process of evolutionary uncertainty reduction. This bilevel process is easily extendible over the whole hierarchy of the system. The method is working in the graph-search and dynamic programming paradigms. The set of problems to be solved is formulated and some of them are addressed. Various applications are contemplated.     

Design of aplanatic waveguide Fresnel lenses and aberration-freeplanar optical systems

A modification of the waveguide Fresnel lens design that has phase-shifting zones placed on the curved contour is suggested. It is shown that the selection of a suitable shape for this contour allows coma aberration to be eliminated. Computer simulation results are presented to demonstrate the significant improvement of the optical characteristics for curved contour lenses. The aplanatic homogeneous refracting waveguide lenses are also considered. It is found that thick aplanatic refracting lenses and the proposed Fresnel lenses have field curvature aberration of opposite sign. This fact allows planar optical systems free from low-order aberration to be designed by combining refracting and Fresnel lenses. An algorithm for producing such a system is presented