Primary intraosseous hemangioma of the orbit: CT and MR appearance

An 8-year-old girl had acute onset of blurred vision, proptosis, and lateral and vertical gaze palsies on the right. CT and MR examinations showed an expansile mass involving the greater wing of the right sphenoid bone. Pathologic analysis of the surgical specimen revealed a capillary hemangioma. The lesion was inhomogeneous but predominantly isointense with gray matter on T1-weighted images. On T2-weighted images the lesion was inhomogeneous with areas of both high and low signal intensity. The rim enhanced uniformly, and there was inhomogeneous enhancement of the bulk of the lesion.     

Fundamental studies of the contribution of galvanic interaction to acid-bacterial leaching of mixed metal sulfides

A systematic study has been made towards understanding the role of galvanic interactions in the leaching of sulfide minerals both in the absence and presence of bacteria. When two sulfide minerals are in contact with each other in an acid-aqueous solution, the mineral lower in the electromotive series dissolves rapidly while the one higher in the series is galvanically protected. To ascertain the magnitude of galvanic interaction when chalcopyrite (CuFeS₂) and pyrite (FeS₂) are in contact, potentiodynamic polarization measurements were carried out in 1 M H₂SO₄ and in Bryner and Anderson medium. The individual rest potentials of CuFeS₂ and FeS₂ were found to be 0.52 V and 0.63 V [vs. Standard Hydrogen Electrode (SHE)] respectively. The mixed potential of the CuFeS₂: FeS₂ couple was found to be 0.56 V and 0.28 V (vs. SHE) in 1 M H₂SO₄ and in Bryner and Anderson medium respectively. The corrosion current (5 μA/cm²) was calculated from the polarization curves. These results were found to be in agreement with the actual leaching rates of copper from contacting large mineral specimens composing the CuFeS₂/FeS₂ system.Both powdered samples as well as large mineral specimens of CuFeS₂, FeS₂ and ZnS were used to observe the effect of galvanic interactions on the process of leaching. Chalcopyrite and pyrite powders, as pulp mixtures, were leached under a variety of experimental conditions to optimize their ratio (total pulp density) and size fraction for efficient metal extraction by way of maximum contact with each other. A CuFeS₂:FeS₂ ratio of 5:5 (g/g) and size fraction of ?200 mesh was found to be the most preferable when leaching was carried out in the presence of T. ferrooxidans. The effect of temperature and thermophilic bacteria on the rate of leaching was also studied. The presence of pyrite in the optimized quantities considerably enhanced the rate of copper dissolution which was increased, by a factor of 2, to 15. Under these experimental conditions, E_h increased from 338 mV to 580 mV while pH dropped from 2.30 to 1.56.In order to have a definite control over surface area of the ores and a constant contact between two sulfide ores, large crystalline-mineral samples of CuFeS₂, FeS₂ and ZnS were leached singly as well as in intimate contact (coupled galvanically). This also made it possible to observe the surfaces of the specimens as the leaching proceeded in the presence of galvanic interaction. Coupled CuFeS₂/FeS₂, ZnS/FeS₂ and CuFeS₂/FeS₂/ZnS systems showed improved metal dissolution as compared to leaching of single large specimens.Scanning electron microscope observations showed that there were no major changes on pyrite surfaces when in galvanic contact with chalcopyrite and/or sphalerite. These observations have been supported by chemical data and by energy-dispersive X-ray analysis.     

A dynamic simulation of a nuclear power station for control analysis

Nonlinear simulation has been applied to the control study of an organic-cooled Canadian CANDU reactor. The study was carried out as an integral part of an overall design study. The control characteristics of the power plant were studied for reactor start-up, pump failures, reactor trips and various rates of power change. The response of the power plant to these disturbances is discussed.     

Status of EPRI''s hydrogen program

EPRI has, through a series of techno-ecomonic studies, market evaluations and a survey of utility consumption of hydrogen, determined that: (a) hydrogen produced by water electrolysis could be of near-term benefit to the utilities, (b) other thermochemical water-splitting cycles do not offer significantly lower costs or improved efficiencies and (c) developing reliable, cost-effective water electrolysers for utility applications would establish a “hands-on” technological basis. The R&D strategy and program plans for development of small (20–50kW) electrolysers for generator cooling, and for evolutionary growth towards use of hydrogen as an energy carrier, are presented.     

Increase in brain stem cytokine mRNA levels as an early response to chemical-induced myelin edema

This study examined the early response of pro-inflammatory and regulatory cytokines in the mouse brain following triethyltin (TET)-induced myelin injury characterized by edematous vacuolation. Following an acute intraperitoneal injection of triethyltin (TET) sulfate (3 mg/kg) to 17-day old CD1 mice, significant increases in brain stem TNF-alpha and IL-1alpha mRNA levels occurred at 6 and 24 h, respectively with elevations in TGF-beta1 and MIP-1alpha at 1 h. In the cortex, responses were limited to elevations at 6 h in TNF-alpha, TGF-beta1 and MIP-1alpha. These data suggest that a chemokine/cytokine response can occur with minimal alterations to the integrity of the myelin sheath and may contribute to the initial signaling mechanisms associated with demyelinating disorders.