Aortic dissection extending from the left coronary artery during percutaneous coronary angioplasty

A 72-year-old woman with acute aortic dissection as a complication of percutaneous coronary angioplasty was successfully treated. She received a graft replacement of the ascending aorta as well as triple coronary artery bypass grafts. The dissection had extended from the left coronary artery. Although acute aortic dissection is a rare complication of percutaneous coronary angioplasty, physicians and cardiac surgeons should keep its potential occurrence in mind.     

Tests of a silica aerogel Cherenkov counter

A Cherenkov counter with silica aerogel of refractive index 1.06 as radiator has been constructed and tested. The Cherenkov light produced in 9 cm thick silica aerogel was detected with four 5″-photomultipliers through a 162 cm long air light guide. The photoelectron yield for a 1 GeV/c pion beam was found to be 6 and uniform over a sensitive area of 40 × 30 cm².     

A case of progressive multifocal leukoencephalopathy with methionine uptake demonstrated by PET]

We report here a 55-year-old man with progressive multifocal leukoencephalopathy (PML) associated with chronic adult T cell leukemia (ATL). Neurological examination revealed mild dementia, right homonymous hemianopsia and visual agnosia. Serologically anti-HTLV-I antibody was positive. Peripheral blood analysis showed ATL cells up to 23% in white blood cells. Because he did not have symptoms or signs directly related to ATL, it was considered that he had chronic ATL. T2-weighted cranial MRI demonstrated multiple hyperintensity lesions confined to the white matter from the bilateral occipital to parietal lobes, without enhancement after gadolinium administration or mass effect. We performed stereotactic biopsy of the left occipitoparietal white matter. Histological examination of the biopsied specimens showed demyelinated lesions, containing foamy macrophages and bizarre astrocytes. Oligodendrocytes contained nuclear inclusions which reacted with an antibody against the JC virus (JCV) antigen. These findings were consistent with those of PML. The genomic analysis of JCV from the biopsied brain revealed deletions in the regulatory region. We investigated cerebral blood flow, glucose and amino acid metabolism in this patient using positron emission tomography, and obtained the following three characteristic findings in the lesions: 1) luxury perfusion state, 2) decreased fluorodeoxyglucose (FDG) uptake, and 3) increased methionine (Met) uptake. These findings resembled those of low grade tumors.     

Effects of salicylate on neural activity in cat primary auditory cortex

The effect of systemically applied salicylate on single-unit firing activity in primary auditory cortex was investigated in six cats. A dose of 200 mg/kg sodium salicylate was administered intraperitoneally, and recordings from the same units were performed prior to application and continuously up to, on average. 6 h after administration. Local field potentials were used to track the threshold shifts and general input-output (I/O) behavior following salicylate administration. All animals showed 20-30 dB of threshold shift about 2 h after administration and showed no recovery during the following 4 h. I/O curves were invariably of the recruitment type. Significant changes were found in spontaneous firing rates for two groups of unit separately. Low-spontaneous rate units (initial firing rate < 1 spike/s) showed an increase in spontaneous rate and high-spontaneous rate units (initial firing rate > 1 spike/s) showed a decrease in spontaneous firing rate. There were no significant changes in modal and mean values for interspike-interval (ISI) histograms. The duration-to-rebound peak in the autocorrelation function for spontaneous firings was prolonged significantly after salicylate administration. Peak cross-correlation coefficients for the firing patterns of simultaneously recorded cells showed no significant change but the correlogram's central peak was significantly narrower after salicylate application. The percentage of firings occurring in bursts showed no significant change after administration of salicylate. The best modulation frequency in response to stimulation with periodic click trains decreased after administration. Both the changes in the spontaneous autocorrelogram and in the temporal modulation transfer function suggest a prolongation in the duration of the Ca(2+)-activated K+ conductance of the cortical pyramidal cells following salicylate. This suggests that salicylates affect both the auditory periphery and the auditory cortex.     

Ductility of a magnesium alloy in warm forging with controlled forming speed using a CNC servo press

The influence of press ram motion on forging performance for magnesium alloys was examined at elevated temperatures using an upsettability test on a CNC servo press. The forging limit of a wrought AZ31B (Mg–3 mass%Al–1 mass%Zn) magnesium specimen, forged using applied deceleration of the press ram motion, was found to be 30% higher than the forging limit achieved without press ram motion control. A finite element analysis was conducted to model the experimental results. The calculated temperature distribution was relatively uniform during upsetting with decelerated ram motion, and the maximum equivalent strain was maintained at a low level. Experimental and simulation results suggested that the influence of the press ram motion on the ductility of the Mg specimen could be described by a strain localization model. Furthermore, the ductility of Mg specimens during decelerated ram motion was improved in backward extrusion.     

Evaluation of joint strength of friction welded carbon steel by heat input

In a search for increases in productivity and to comply with labour laws, companies have focused on questions related to health and safety at work. Among the many risks involved in the welding scenario (fumes, electric shock, mechanical crushing by movable parts in pressure processes, or jig systems, etc.), non-ionizing radiation stands out as a major concern in the arc welding process and some authors have called for attention to measuring ultraviolet (UV) radiation. This radiation measurement can be applied to the development of welding processes or to establish less hazardous conditions for human beings where robotic welding is not suitable. As a result, the aim of this work is to present a comparison of radiation levels in terms of different wavelength ranges (UV-total and visible, UV-A, UV-B, and UV-C) for different arc welding processes (GTAW, GMAW, SMAW, and FCAW). It is expected that the results will lead to a more in-depth discussion on this subject.     

A computer simulation of strength of metal matrix

The deformation and fracture behavior of metal matrix composites with a reaction layer at the fiber-matrix interface was studied by means of a computer simulation experiment, using a two-dimensional model, and the results of the simulation experiment were compared with the predictions based on the single fiber model, which has been proposed to describe the reduction of strength of composites due to a reaction layer. In the simulation experiment, the composite was regarded as an assembly of single fiber elements, in which, for each element, the reaction layer introduces a notch on the fiber surface when it is broken, which reduces the strength of the fiber if the thickness of the layer is thinner than a critical value, as has been studied by using the single fiber model. The strength of composites was reduced with increasing thickness of the reaction layer and the fracture mode became catastrophic. The strength values obtained by the simulation were equal to those based on the single fiber model only when the fracture of the fiber was caused by the extension of the notch having been introduced by premature fracture of the reaction layer. In other cases, the strength values of the simulation were lower than those predicted by the single fiber model, although the single fiber model gave approximate values.     

Hydrolysis and condensation mechanisms of a silane coupling agent studied by 13C and 29Si NMR

The mechanisms of hydrolysis and condensation of a silane coupling agent, γ-methacrylo-xypropyltrimetoxysilane (γ-MPTS) were investigated by the use of both ¹³C and ²⁹Si nuclear magnetic resonance (NMR) spectroscopies. The NMR peaks of the hydrolyzed monomer and condensed polymer were assigned readily. The rate of hydrolysis and condensation of γ-MPTS was dependent on water content. On the basis of the time-dependent behavior of these peaks, the mechanisms of hydrolysis and condensation were clear.