Search

Dual two-phase intermetallic alloy that has an alloy composition of Ni75Al9V13Nb3 and is composed of geometrically close packed (GCP) Ni3Al (L12) and Ni3V (D022) phases was studied, focusing on the effect of TiC addition on high-temperature tensile properties. The two-phase microstructures defined by primary Ni3Al precipitates and eutectoid region consisting of Ni3Al and Ni3V phases were kept and were dispersed by TiC particles. EPMA analysis showed that alloy compositions in matrix of the TiC added alloy were different from those in the base alloy. The positive temperature dependence of flow strength was observed for all TiC added alloys. In low temperature range the maximum strengthening took place at 1 at.% TiC content. On the other hand, tensile elongation increased with increasing TiC content up to 1 at.% TiC content and was independent of TiC content over 1 at.% in whole temperature ranges. Also, the TiC addition resulted in change of the fracture mode from brittle transgranular fracture to ductile transgranular fracture in low temperature range, and from brittle intergranular fracture to ductile transgranular fracture in high-temperature range. Possible mechanisms responsible for the strengthening and ductilization by TiC addition were interpreted, based on the behavior of C and Ti solutes, and Nb solute in the matrix, which were decomposed from TiC and affected by TiC addition, respectively.

Aims Although increased digitalis-like immunoreactive substances have been found in cases of hypertension and heart failure, no information is available about digitalis-like immunoreactive substances in patients with hypertrophic cardiomyopathy. We investigated digitalis-like immunoreactive substances in the plasma and biopsied specimens of patients with hypertrophic cardiomyopathy. Methods and Results In 40 patients with hypertrophic cardiomyopathy (27 with the non-obstructive type and 13 with the obstructive type), the plasma concentration of digitalis-like immunoreactive substances was studied by fluorescence polarization immunoassay. Right ventricular endomyocardial biopsy specimens were analysed immunohistochemically, using a monoclonal antibody against digoxin. An increase in digitalis-like immunoreactive substances of more than 0·2ng.ml−1in plasma was found in six of 27 patients with non-obstructive hypertrophic cardiomyopathy (22·2%) and five of 13 with obstructive hypertrophic cardiomyopathy (38·4%). Under light microscopy, positive staining against the antibody was observed heterogeneously on some cardiocytes. In non-obstructive hypertrophic cardiomyopathy, digitalis-like immunoreactive substances in the plasma correlated with the left atrial dimension and inversely with the cardiac index. In obstructive hypertrophic cardiomyopathy, plasma and myocardial digitalis-like immunoreactive substances were positively correlated; they also correlated with left ventricular end-diastolic pressures. Under electron microscopy, digitalis-like immunoreactive substances were detected at the sarcolemma in the free wall, T-tubules, intercalated discs and Z-bands of cardiocytes. Conclusions Increased digitalis-like immunoreactive substances in plasma and cardiocytes, which may have been caused by pressure and/or volume overload, were found in patients with hypertrophic cardiomyopathy. Digitalis-like immunoreactive substances may act on the sarcolemma of cardiocytes and be transported into the cytoplasm.

Asymmetric tilt-angle-implanted lightly doped drain (LDD)-WN/sub x/-GaAs MESFETs with an optimized transconductance performance are discussed. A tilt-angle implantation is used to reduce the parasitic source resistance below the gate sidewall without increasing short- and narrow-channel effects. This leads to a transconductance increase of nearly 25% for submicrometer FETs while the gate-source capacitance increase is almost negligible. The influence of the implantation angle on the threshold voltage transconductance, and Schottky-barrier characteristics is reported. >

Alzheimer’s disease (AD) is characterized by cognitive and memory dysfunctions, and is accompanied by default mode network (DMN) abnormalities. We investigated the neurophysiological basis of these dysfunctions by examining functional connectivity using standardized low resolution electromagnetic tomography (sLORETA). Resting, eyes closed EEGs were recorded from 19 patients with mild AD and 22 healthy control subjects. Electrophysiological connectivity maps between parahippocampal gyri and all other cortical regions were computed, as well as pairwise connectivity among DMN regions. Between-group comparisons in 7 frequency bands were carried out. Beta2 connectivity was marginally decreased between right parahippocampus and right superior frontal gyrus, right precentral gyrus, and right occipital lobe in AD patients. They also showed significantly decreased alpha2 and beta2 connectivity between posterior cingulate gyrus and right inferior parietal lobe within DMN. Previous fMRI studies have shown AD decreased connectivity between parahippocampus, where significant neurological degeneration appears, and other brain regions. The disconnection between the hubs of DMN in sLORETA connectivity suggest AD patients have an abnormal DMN, in agreement with previous fMRI resting state networks studies. sLORETA connectivity provides complimentary information on the neurophysiological dysfunction between parahippocampus and other cortical areas, and on the DMN aberrance in patients with AD.

Long-chain fatty acids (LCFA) are the major energy substrate for heart and their oxidation is important for achieving maximal cardiac work. However, the mechanism of uptake of LCFA by myocardium has not been clarified. We previously reported that bovine myocardial LCFA transporter has a sequence homology to human CD36. Clinically, total defect of myocardial uptake of radiolabeled long-chain fatty acid analog [123I-BMIPP: Iodine-123 15-(p-iodophenyl)-(R,S)-methylpentadecanoic acid] has been reported in some restricted cases, but the etiology has not been clarified. In the present study, we analyzed CD36 expression and CD36 gene in subjects who showed total lack of myocardial 123I-BMIPP accumulation, and, vice versa, evaluated myocardial 123I-BMIPP uptake in subjects with CD36 deficiency. Four unrelated subjects were evaluated, Two were found to have negative myocardial LCFA accumulation by 123I-BMIPP scintigraphy, after which the expression of CD36 on their platelets and monocytes was analyzed. Remaining two subjects were identified as CD36 deficiency by screening, then 123I-BMIPP scintigraphy was performed. Expression of CD36 on platelets and monocytes was measured by flow cytometric analysis. The molecular defects responsible for CD36 deficiency was detected by allele-specific restriction enzyme analysis. CD36 expression was totally deficient in all 4 subjects on both platelets and monocytes. Two subjects were homozygous for a 478C--T mutation. One was heterozygous for the dinucleotide deletion of exon V and single nucleotide insertion of exon X, and remaining one was considered to be heterozygous for the dinucleotide deletion of exon V and an unknown gene abnormality. All cases demonstrated a completely negative accumulation of myocardial LCFA despite of normal myocardial perfusion, which was evaluated by thallium scintigraphy. In addition, all cases demonstrated apparently normal hepatic LCFA accumulation Thus, these findings suggested that CD36 acts as a major myocardial specific LCFA transporter in humans.

Reliability of Ti–Pt–Au and Ti–Mo–Au systems has been investigated for GaAs integrated circuit first‐level metallizations on semi‐insulating GaAs substrates and second‐level metallizations on interlayer SiO2 films using Auger depth profile analysis, residual resistance examination and temperature storage step‐stress testing. Auger analysis and residual resistance examination showed significant reaction between first‐level Ti–Pt–Au and GaAs substrates during metallization processes, while Ti–Mo–Au system with the electron‐beam evaporated Mo film showed higher thermal stability because the Mo film acted as a good diffusion barrier between GaAs and Au. The second‐level Ti–Pt–Au on SiO2 was found to be free from the reaction with GaAs substrates, and its degradation was ascribed to interdiffusion of composite metals. The resistance increase in step‐stress testing for the second Ti–Pt–Au was analyzed on the basis of a new diffusion‐controlled model, and long‐term reliability was estimated. A mean time to failu...