FATIGUE LIMIT OF BLUNT-NOTCHED COMPONENTS

The position and effective resistance of microstructural barriers and their relation to the fatigue strength of blunt-notched specimens are analysed and modelled for three low-carbon steel microstructures. A relationship for the notch size effect on the basis of the experimental evidence that the fatigue limit (both plain and notched) represents the threshold stress for the propagation of the nucleated microstructurally short cracks, was derived. The derived relationship characterizes the fatigue notch sensitivity by means of the parameter k_td defined as the stress concentration introduced by the notch at a distance d from the notch root surface equal to the distance between microstructural barriers, and was experimentally verified for two notch geometries in three microstructures: ferrite, ferrite–bainite and bainite–martensite.     

Poly(ethylene oxide) macromonomers

Summary p-Vinylbenzyl-terninated poly(ethylene oxide) macromonomers (M₂) were radical-copolymerized with styrene (M₁) in benzene, tetrahydrofuran, and methyl isobutyl ketone at 60°C. Relative reactivity of the macromonomer toward polystyryl radical, as estimated by l/r₁ was found to decrease with increasing number-average degree of polymerization and also in a solvent which gives a higher [] of both polystyrene and the macromonomer. The results support our previous suggestion that a repulsion between the macromonomer and the propagating polymer radical can be a factor responsible for disturbing their mutual reaction.Part 1: Ref. 1, Part 2: Ref. 2     

An additional variant of the persistent primitive trigeminal artery: accessory meningeal artery--antero-superior cerebellar artery anastomosis associated with moyamoya disease

Neuropathy is a frequent complication in diabetes mellitus. Since the involvement of the autonomic nervous system indicates a poor prognosis, early detection and subsequent management are important. Analysis of heart rate variability (HRV) provides a quantitative measure of sympathovagal modulation activities on the heart and has been proven to be useful for the early assessment of the diabetic autonomic neuropathy. We recently developed a simple method of measuring pulse wave velocity (PWV) to evaluate sympathetic nervous activity in the vascular system. In this paper, we examined 33 diabetic patients with and without peripheral neuropathy (15 and 18 respectively) using these methods. In time domain analysis, the mean heart rate, standard deviation and coefficient of variation of HRVs significantly differed between these two groups, whereas the indices of PWVs did not show a significant difference. In frequency domain analysis of HRV, both low and high frequency components were decreased, and the low frequency component in normalized unit did not increase after standing in patients with peripheral neuropathy. We previously reported that the mean PWV decreased after standing in patients with diabetic neuropathy. This disagreement suggests that beta sympathetic dysfunction precedes alpha sympathetic dysfunction in diabetic neuropathy.     

Effects of ACE inhibitor on renal anemia in predialysis patients

Enterocolitis necroticans or pigbel is a rare condition characteristically affecting chronically malnourished people who abruptly increase their intake of protein. The classic presentation of the disease as seen in the highlands of Papua New Guinea is that of a necrotising enterocolitis after the ritual ingestion of contaminated pork. In this context, the presentation of the same disease in a well nourished white vegetarian in Oxford was all the more intriguing.     

S.A.W. right-angle reflection coefficient from metal strip array reflector on y-cut LiNbO3

The s.a.w. reflection coefficient of the metal strip has been measured on y-cut LiNbO3 for waves reflected through 90° from the z into the x direction. The maximum value of the reflection coefficient of a metal strip is 0.020, when the width/periodicity ratio of the metal strips is about 0.3.     

InGaAs avalanche photodiode with InP p-n junction

A new InGaAs avalanche photodiode structure that has an InGaAs light absorption region and InP avalanche multiplying region is proposed. A dark-current density of 2.2 × 10?3 A/cm2 at 90% of breakdown voltage and a multiplication factor of 45 were obtained for the new structure diode fabricated from a liquid-phase epitaxially grown wafer.     

High-gain GaAs avalanche photodiodes with proton-implanted guard ring

A GaAs avalanche photodiode with a multiplication factor as high as 8000 was prepared by Zn diffusion and proton double implantation. The proton-implanted guard ring completely prevented edge breakdown, and multiplication occurred uniformly over the junction area. Dark current was proved to be due to a leakage current at the periphery between junction and implanted layer.     

Growth of silicon nanowires on H-terminated Si {111} surface templates studied by transmission electron microscopy

We have studied the growth of silicon nanowires (SiNWs) by means of transmission electron microscopy. SiNWs are grown from nanocatalysts via the Vapor-Liquid-Solid (VLS) mechanism using silane (SiH4) gas as a source gas. The nanocatalysts are prepared on a hydrogen (H)-terminated Si surface. We have examined the formation mechanism of nanocatalysts on H-terminated surface and have observed several structural variants of SiNWs. According to the study we have suggested that many structural variations of SiNWs are possible, which modify the structural properties of SiNWs to great extents.     

Hepta-and nonadecene from marine fish

Two monoalkenes were detected in gizzard shad (Clupanodon punctatus) and sardine (Sardinops melanosticta) by gas chromatography and were identified by combined gas chromatography-mass spectrometry of their cyclic boronate and dioxolane derivatives ascis-6-n-heptadecene andcis-8-n-nonadecene.