Effect of low temperature and environment on the kinetics of fatigue crack growth in VT5-1kt titanium alloy with different microstructures

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 27, No. 6, pp. 69–71, November–December, 1991.     

Optimal Control of Solar Sludge Dryers

Optimal control (OC) methodology is used to develop a control policy for a batch-operated solar sludge dryer with ventilation as the dominant control. Batch performance criteria and instantaneous optimization criteria are developed for two economic environments: quota limited and capital limited. The general formulation, as well as simplifications resulting from the multiplicative form of the evaporation (drying) rate model, are presented. The multiplicative form results in a single constant number, called here “control intensity,” which is used to guide the on-line control decisions. These decisions turn out to be independent of the dry solids content (DSC) of the sludge. Further simplification, by assuming a strictly constant weather, is used to demonstrate the general effects of the economic and physical (weather) environment on the solution.

The OC approach is used to address, via simulation under realistic weather conditions, several design, operation, and pricing problems. In particular, the following have been considered: sizing of the ventilation fans, determination of a fair fee for sludge disposal, finding the best final DSC, and evaluating the effect of the price of electricity. Regarding the particular location represented by the data, it has been shown that the installed capacity of the ventilation fans should be increased and that there seems to be sufficient economic incentive for solar drying.     

Dislocation structure of diffusion layers of boron in iron

Conclusion The dislocation structure and the microstructure of diffusion layers, which at the temperature of diffusion annealing represent a single-phase solid solution of boron in -iron, are determined by the local boron concentration and by the cooling rate from the austenitic state. The high dislocation density in the layer, which is found independently of the cooling rate, testifies to the fact that diffusion of boron in iron is accompanied by the formation of a large number of dislocations. The presence of boron in the solution slows down their redistribution and annihilation in the porcess of high-temperature annealing.The distribution of microdistortions across the thickness of the layer is characterized by the existence of a maximum near the diffusion line; this is due to the high density of the randomly distributed dislocations on the boundary between the diffusion zone and iron.Tula Polytechnic Institute. Translated from Metallovedenie i Termicheskaya obrabotka Metallov, No. 1, pp. 20–23, January, 1988.     

Therapeutic Effects of hiPSC-Derived Glial and Neuronal Progenitor Cells-Conditioned Medium in Experimental Ischemic Stroke in Rats

Transplantation of various types of stem cells as a possible therapy for stroke has been tested for years, and the results are promising. Recent investigations have shown that the administration of the conditioned media obtained after stem cell cultivation can also be effective in the therapy of the central nervous system pathology (hypothesis of their paracrine action). The aim of this study was to evaluate the therapeutic effects of the conditioned medium of hiPSC-derived glial and neuronal progenitor cells in the rat middle cerebral artery occlusion model of the ischemic stroke. Secretory activity of the cultured neuronal and glial progenitor cells was evaluated by proteomic and immunosorbent-based approaches. Therapeutic effects were assessed by overall survival, neurologic deficit and infarct volume dynamics, as well as by the end-point values of the apoptosis- and inflammation-related gene expression levels, the extent of microglia/macrophage infiltration and the numbers of formed blood vessels in the affected area of the brain. As a result, 31% of the protein species discovered in glial progenitor cells-conditioned medium and 45% in neuronal progenitor cells-conditioned medium were cell type specific. The glial progenitor cell-conditioned media showed a higher content of neurotrophins (BDNF, GDNF, CNTF and NGF). We showed that intra-arterial administration of glial progenitor cells-conditioned medium promoted a faster decrease in neurological deficit compared to the control group, reduced microglia/macrophage infiltration, reduced expression of pro-apoptotic gene Bax and pro-inflammatory cytokine gene Tnf, increased expression of anti-inflammatory cytokine genes (Il4, Il10, Il13) and promoted the formation of blood vessels within the damaged area. None of these effects were exerted by the neuronal progenitor cell-conditioned media. The results indicate pronounced cytoprotective, anti-inflammatory and angiogenic properties of soluble factors secreted by glial progenitor cells.     

Role of Chiral Configuration in the Photoinduced Interaction of D- and L-Tryptophan with Optical Isomers of Ketoprofen in Linked Systems

The study of the L- and D-amino acid properties in proteins and peptides has attracted considerable attention in recent years, as the replacement of even one L-amino acid by its D-analogue due to aging of the body is resulted in a number of pathological conditions, including Alzheimer’s and Parkinson’s diseases. A recent trend is using short model systems to study the peculiarities of proteins with D-amino acids. In this report, the comparison of the excited states quenching of L- and D-tryptophan (Trp) in a model donor–acceptor dyad with (R)- and (S)-ketoprofen (KP-Trp) was carried out by photochemically induced dynamic nuclear polarization (CIDNP) and fluorescence spectroscopy. Quenching of the Trp excited states, which occurs via two mechanisms: prevailing resonance energy transfer (RET) and electron transfer (ET), indeed demonstrates some peculiarities for all three studied configurations of the dyad: (R,S)-, (S,R)-, and (S,S)-. Thus, the ET efficiency is identical for (S,R)- and (R,S)-enantiomers, while RET differs by 1.6 times. For (S,S)-, the CIDNP coefficient is almost an order of magnitude greater than for (R,S)- and (S,R)-. To understand the source of this difference, hyperpolarization of (S,S)-and (R,S)- has been calculated using theory involving the electron dipole–dipole interaction in the secular equation.     

Effect of crystallization conditions of pulse die forging on structure formation in TiAl-and Ti3Al-base alloys

The structure and properties of alloys based on TiAl and Ti₃Al titanium aluminides obtained by the method of pulse die forging are studied. It is shown that the content of aluminum and the changes in the structural factors (the grain size and the width of Ti₃Al lamellas) that control the strength characteristics of TiAl-base alloys with lamellar structure are correlated.     

High-temperature rheological properties of clay bodies and bodies plasticized with clay

Conclusions We determined the rheological properties of clay materials at elevated temperatures. With an increase in the temperature and pressure the structural-mechanical constants diminish, and the plasticity increases. The total proportion of elastic and plastic deformations reaches significant values (92–95%) in kaolins at 1450°C, and in Chasov-Yar clay at 1200–1250°C. It is in these conditions precisely that we obtain the densest thermal-pressed products.With optimum thermoplastic pressing temperatures the various clay materials have the closest viscosity and maximum yield point values.The best natural raw material for thermoplasticizing is Chasov-Yar clay, but it is possible to use other clay materials. It is possible to regulate the rheological properties of bodies by varying the compositions (filler + thermoplasticizer) of the bodies, the pressing temperature, and pressure.The rheological properties of mixtures of zircon and thermoplasticizer (10% Chasov-Yar clay) at 1450–1480°C facilitate the production of especially dense products for continuous steel casting. Tests carried out on continuous casting plant were successful.Translated from Ogneupory, No. 6, pp. 43–51, June, 1973.