Optimizing the geometrical parameters in a group of high- and intermediate-pressure stages used in large steam turbines

An algorithm for calculating a turbine flow path compartment is considered using which it is possible to minimize the loss of energy in a group of stages while fulfilling strength limitations. The calculations were carried out using information from a database containing the generalized characteristics of flow path elements obtained from tests. Calculation examples are given, the results of which are compared with the data of previous calculations carried out for a compartment in the high-pressure cylinder of a K-800-240 turbine.     

Morphology control and luminescence properties of YAG:Eu phosphors prepared by spray pyrolysis

Starting from nitrate aqueous solutions with citric acid and polyethylene glycol (PEG) as additives, Y₃Al₅O₁₂:Eu (YAG:Eu) phosphors were prepared by a two-step spray pyrolysis (SP) method. The obtained YAG:Eu phosphor particles have spherical shape, submicron size and smooth surface. The effects of process conditions of the spray pyrolysis on the crystallinity, morphology and luminescence properties of phosphor particles were investigated. The emission intensity of the phosphors increased with increasing of sintering temperature and solution concentration due to the increase of the crystallinity and particles size, respectively. Adequate amount of PEG was necessary for obtaining spherical particles, and the optimum emission intensity could be obtained when the concentration of PEG was 0.10 g/ml in the precursor solution. Compared with the YAG:Eu phosphor prepared by citrate-gel (CG) method with non-spherical morphology, spherical YAG:Eu phosphor particles showed a higher emission intensity.     

Spatial association of prekinetochores and chromocentres in the interphase nuclei of mouse cultured fibroblasts

The literature has been reviewed to evaluate the technique and clinical value of radionuclide measurements of microvascular permeability and oedema formation in the lungs. Methodology, modelling and interpretation vary widely among studies. Nevertheless, most studies agree on the fact that the measurement of permeability via pulmonary radioactivity measurements of intravenously injected radiolabelled proteins versus that in the blood pool, the so-called pulmonary protein transport rate (PTR), can assist the clinician in discriminating between permeability oedema of the lungs associated with the adult respiratory distress syndrome (ARDS) and oedema caused by an increased filtration pressure, for instance in the course of cardiac disease, i.e. pressure-induced pulmonary oedema. Some of the techniques used to measure PTR are also able to detect subclinical forms of lung microvascular injury not yet complicated by permeability oedema. This may occur after cardiopulmonary bypass and major vascular surgery, for instance. By paralleling the clinical severity and course of the ARDS, the PTR method may also serve as a tool to evaluate new therapies for the syndrome. Taken together, the currently available radionuclide methods, which are applicable at the bedside in the intensive care unit, may provide a gold standard for detecting minor and major forms of acute microvascular lung injury, and for evaluating the severity, course and response to treatment.     

Oxygen-doped ZnTe phosphors for synchrotron X-ray imaging detectors

ZnTe:O powder phosphors were successfully prepared by a dry synthesis process using gaseous doping and etching media. It was found that dry doping by O₂ through ball-milling was an effective way to synthesize ZnTe:O powder phosphors and produced a red emission centered at 680 nm with a decay time of 1.1 μs. The emission intensity of dry O₂-doped samples was three times more intense than from ZnO-doped samples, possibly due to a more uniform distribution of oxygen substitution on tellurium sites. The samples annealed in a 95% N₂/5% H₂ forming gas atmosphere exhibited a x-ray luminescent efficiency five times higher than did powders annealed in vacuum or N₂ atmosphere. This enhancement was attributed to the removal of surface tellurium oxides. ZnTe:O phosphor screens were prepared with x-ray luminescence efficiencies equivalent to 56% of ZnSe:Cu,Ce,Cl and 76% of Gd₂O₂S:Tb screens under 17-keV radiation. An x-ray imaging resolution of 2.5 lines/mm was resolved, the same as that measured for commercial ZnSe:Cu,Ce,Cl and Gd₂O₂S:Tb screens. These results indicate that ZnTe:O is a promising phosphor candidate for synchrotron x-ray imaging applications.     

Efficient near-infrared downconversion in GdVO4:Dy phosphors for enhancing the photo-response of solar cells

Near-infrared (NIR) downconversion (DC) has been observed in a Dy³⁺-doped GdVO₄ phosphor, where one ultraviolet-blue photon can be split efficiently into two NIR photons. Underlying mechanism for the process of NIR-DC is analyzed in terms of absorption spectrum, static and dynamic photoemission and monitored excitation spectra. Internal quantum efficiency is obtained up to 111% on the basis of experimental and theoretical calculation results. This enables the phosphor promising in significant enhancement of spectral response of silicon solar cells, particularly in the range of 200-500 nm.     

Analysis of trends in the development of cities’ heat supply systems

New challenges—including the modern urban development policy, formation of the market of energy efficient technologies and different types of equipment of a broad power capacity range, tightening requirements to reliability, quality, and economic accessibility of heat supply—enhance the competitiveness of decentralized heat supply. In addition, its spontaneous growth and not always reasonable implementation lead to unjustified expenses, low efficiency, and ecological inconsistency. This proves the relevance of solving the problems of dividing an urban territory into zones of centralized heating (CH) and decentralized heating (DCH) along with their planning and justification, as well as determining a reasonable level of heat supply centralization and concentration of heat sources' power capacity. Solving these problems using the suggested method will allow optimizing the application areas for various types of heat supply and heat sources, justifying the degree of heat power capacity concentration and the extent of the systems as early as at the phase of a detailed urban planning project and then refining them during the design of urban heat supply systems. This will dramatically improve the reasonability of the decisions made and will simplify the procedure of their implementation. For criteria of limiting the extent (radius) of heat supply systems and defining their type, we suggest using standard values—the density of heat load per unit length of the pipeline and per unit area of urban territory. Standard values must be differentiated across the territory of Russia taking into account regional climatic and economic conditions and unique characteristics of heat supply development in cities and towns. The present article continues and develops the statements made in the previous articles created within the framework of the Theory of Hydraulic Circuits and takes into account the current situation and emerging trends in heat supply.     

Cholinergic excitation of dendrites in neocortical neurons

Discharge patterns were studied in response to iontophoretic application of acetylcholine to the soma and dendrites of 128 neocortical pyramidal neurons of layer V. Extracellular recordings were obtained from slices of the guinea-pig parietal cortex. All responses found were excitatory and were better expressed in spontaneously firing cells than in silent ones. Sensitivity to acetylcholine was approximately the same at somatic and dendritic sites in all the cells. Activation of muscarinic receptors gave rise to firing patterns with equal latencies and intensities when applied to both soma and dendrites. The latter suggests that membrane excitation elicited in dendrites by binding of acetylcholine to muscarinic cholinoreceptors is likely to propagate towards the soma through intracellular biochemical processes. Modulating effect of acetylcholine on output firing patterns, elicited by dendritic application of excitatory amino acids, included shortening of the somatic response latency and increase of response intensity and duration. We propose that, in contrast to glutamatergic excitation, the spread of cholinergic excitation along dendrites involves intra-cellular chemical signalling and results in changing the electrical properties of dendrites all over their length.