Physical properties of a sprinkler water spray

This paper reports an experimental study on the physical properties of a sprinkler water spray. The mass flux density, shape of spray pattern, size distribution and velocity of water droplets discharged from two types of 15 mm orifice sprinkler heads were measured. Three operating flow conditions of the sprinkler system, including one specified for the Ordinary Hazard class under the LPC rules for sprinkler design, were set. The sprinkler head was installed above finished floor levels of either 2 m or 2.2 m. The median droplet size was found to be related to the water pressure and the orifice diameter of the sprinkler head as proposed by Dundas. The droplet size distribution function can be fitted by a Rosin–Rammler function.     

Silicon LEDs with room-temperature dislocation-related luminescence, fabricated by erbium ion implantation and chemical-vapor deposition of polycrystalline silicon layers heavily doped with boron and phosphorus

Light-emitting diodes (LEDs) have been fabricated in which optically active centers are formed by implantation of erbium ions into silicon and subsequent high-temperature annealing in an oxidizing atmosphere and the p-n junction and the ohmic contact are formed by chemical vapor deposition of polycrystalline silicon layers doped with boron and phosphorus, respectively. The luminescent properties of the LEDs have been studied. Use of polycrystalline layers makes it possible to eliminate the losses in the bulk of the light-emitting Si:Er layer. These losses are inevitable if the conventional ion implantation and diffusion methods are employed. At 80 K, the variation of electroluminescence spectra in the spectral range of the dislocation-related luminescence with the drive current is well described if the spectrum is decomposed into three Gaussian components whose peak positions and widths are current-independent and amplitudes linearly increase with the current. At 300 K, a single peak is observed in the spectral range of the dislocation-related luminescence at ～1.6 μm.     

Early-stage widmanstatten growth of the γ phase in a duplex steel

The present work studies the Widmanstatten γ-phase morphology and crystallographic orientation relationships with ferrite during its initial-stage growth in a duplex steel. Transmission electron microscopy (TEM) and convergent-beam electron diffraction (CBED) analyses have been applied to determine the orientation relationships with high precision. When the secondary γ phase and the α phase have special orientation relationships close to the K-S (Kurdjumov-Sachs) relation, the preferential growth involves γ phase, protruding into α phase and this leads, finally, to the formation of Widmanstatten needles. The needles grow nearly along the invariant-line direction, but they do not satisfy exactly the K-S relation, and a slight angular deviation (ϑ _[110]α ) is always present. This deviation is explained by a compromise between the well-known invariant-line condition, which offers the easiest way for directional growth of the γ phase, and a good atomic matching of the close-packed (111) _γ and (110) _α planes of both phases. A matching minimum at ϑ _[110]α = 2.3 deg is obtained when only three pairs of the nearest-neighbor atoms are considered in an atomic misfit calculation.     

Effect of Electropulsing on Recrystallization and Mechanical Properties of Silicon Steel Strips

Electropulsing-induced recrystallization and its effect on mechanical properties of oriented silicon steel strips (Fe-3.0%Si) were studied by optical microscopy, scanning electron microscopy and electron back-scatter diffraction. The results indicated that electropulsing accelerated recrystallization, and decreased the temperature of recrystallization. Electropulsing favors refinement of the grain structure of the alloy. Effects of electropulsing on strength and elongation of the alloy were discussed from the point view of dislocation dynamics, microstructural changes, and electropulsing kinetics.     

Microstructural and photoluminescence properties of tin dioxide modified by electron beam irradiation

A modified technique was developed by electron beam irradiation to prepare tin dioxide (SnO2) nanocrystals using the sol-gel method. SnO2 nanoparticles were radiated under a 1,400 KGy dose. The morphology and microstructure of the SnO2 nanocrystals were investigated by X-ray diffraction, high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The results indicate that the irradiated SnO2 nanoparticles have better crystallinity than unirradiated SnO2 nanoparticles, and the resulting nanocrystals have a tetragonal rutile crystalline structure. The HRTEM image proves that the average grain size is about 4 nm, and the clear lattice fringes indicate the improvement of SnO2 nanocrystals after irradiation. The Raman spectrum shows that there are new peaks at 535 cm(-1) and 691 cm(-1). The optical properties of SnO2 nanoparticles were characterized by ultraviolet-visible (UV-vis) and photoluminescence spectrophotometers. The band gap energy of the irradiated SnO2 was 3.29 eV smaller than that of the unirradiated SnO2 due to size effects and some defects of SnO2 nanocrystals. This work provides a novel approach for the improvement of SnO2 nanocrystals. The optical properties of the irradiated SnO2 nanomaterials are also expected to improve.     

Repeated hepatectomies for recurrent follicular dendritic cell tumour of liver: a case report

Follicular dendritic cell tumour is a very rare tumour of unknown aetiology. We report a case of follicular dendritic cell tumour of liver which was treated with extended right hemihepatectomy but recurred twice in the remaining left lobe within 3 years. The recurrent tumours were removed by further liver resection. The mainstay of treatment for this rare tumour is surgical resection.     

Impact of physical activity and sport on the immune system

This review describes how exercise and physical training affect the immune system. Although many immune functions are stimulated by moderate physical activity, more vigorous effort and periods of heavy training suppress various immune response parameters. Experimental studies from our own laboratories and elsewhere illustrate that cellular infiltration of the active muscle is accompanied by phagocyte activation, suppressed NK-cell function, impaired lymphocyte proliferation, decreased in-vitro immunoglobulin production, pro-inflammatory eicosanoid release, cytokine cascade activation, and altered expression of cytokine receptors. Examples cover deliberate heavy training; single bouts of fatiguing, submaximal work; repeated bouts of exercise; and ultra-long distance athletic events. In young adults, age, environment, and light physical training do not change immune-response parameters. Parallels between immune impairment after vigorous exercise and reactions to surgical sepsis are noted. Vigorous exercise probably induces subclinical muscle injury and an associated inflammatory response. Heavy exercise may be a useful experimental model for developing more effective treatments for sepsis. For protection average athletes may take the anti-oxidant vitamins C and E and non-steroidal inflammatory drugs, if the muscles show signs of an inflammatory reaction. Top-level athletes have received immunoglobulin preparations.