Library

Notes: [Auszug] Solid-state superconducting circuits are versatile systems in which quantum states can be engineered and controlled. Recent progress in this area has opened up exciting possibilities for exploring fundamental physics as well as applications in quantum information technology; in a series of ...

Notes: summary  The effect of jaw clenching on local blood flow in the masseter muscle was measured using the hydrogen clearance method in 13 healthy subjects. Sustained isometric masseter-muscle contraction levels of 25 and 50% of maximum voluntary contraction (MVC) were investigated. The blood flow at 25% MVC before contraction, during contraction and after contraction was 12·3 ± 10·9, 19·2 ± 12·1 and 78·8 ± 63·9 mL min−1 (100 g)−1 (mean ± s.d.), respectively. At 50% MVC, it was 14·2 ± 12·9, 18·6 ± 10·0 and 80·1 ± 61·8, respectively. The volume of blood flow was significantly greater after contraction as compared with before contraction at both levels (P 〈 0·0001) and there was no significant difference between before and during contraction periods (P = 0·17: 25% MVC; P = 0·38: 50% MVC). At 50% MVC blood flow before contraction and the difference in blood flow before and during contraction showed significant negative correlation (r = −0·636, P 〈 0·02). When the volume of blood flow was low before contraction it tended to increase during contraction and decreased when it was high before contraction. These findings indicate that blood flow in the masseter muscle during sustained isometric contraction is affected by the condition of contraction and may be influenced by the muscle region. It was also indicated that the blood flow during high level contraction was influenced by the volume of blood flow before contraction. Clinically, our findings may help to understand pathological changes which may lead to chronic masticatory muscle pain.

Notes: summary  In the present study, the biocompatibility of mineral trioxide aggregate (MTA) to the revascularization of the connective tissues was evaluated by using the improved rabbit ear chamber, in vivo. Twenty improved rabbit ear chamber was prepared from 12 male albino-rabbit by using a well through which a material could be introduced into the living vascular tissue. Ten chambers were provided for MTA, and the remaining 10 chambers were used for a calcium hydroxide-containing root canal sealer (Sealapex), as a comparator. A volume of about 1·5 mm3 of the materials were inserted into the chamber and the interaction between the vascular tissue and materials was observed by using a biomicroscope immediately after application, at 1, 3, 5·5, 8, 24, 48, 72 h, and once a week up to 4 weeks. The results revealed that revascularization of connective tissue took place with complete recovery of microcirculation within 4 weeks in both MTA and Sealapex. However, the precipitate-barrier and brown zone around periphery of Sealapex was not observed in MTA treated samples. It can be concluded that MTA is biocompatible and does not produce any adverse site effect on microcirculation of the connective tissue.

Notes: Background : The incidence and severity of non-steroidal anti-inflammatory drugs (NSAIDs)-induced gastro-duodenal ulcer have not been extensively studied in Japan.Aim : We performed a prospective study to clarify NSAIDs-induced gastro-duodenal injury, focusing especially on low-dose aspirin (L-A).Methods : Two hundred and thirty-eight patients with bleeding peptic ulcers admitted to our hospital. History of taking NSAIDs and anti-ulcer drugs was obtained from all patients who underwent endoscopic examinations. The lesion scores of patients taking L-A were classified numerically from zero (no lesion) to five (ulcer).Results : The NSAIDs were associated with 28.2% of hemorrhagic ulcers. The rates of patients using L-A, loxoprofen, diclofenac, and combination of two of these drugs were 27, 16, 10 and 9%, respectively. Co-administered anti-ulcer drugs were cytoprotective anti-ulcer drugs (27%), H2 receptor antagonists (16%), PPI (4%), and none (53%). In patients taking L-A, H2 receptor antagonists were used most frequently. The HP was positive in 63% of L-A-induced ulcer cases and in 69% of NSAIDs other than low-dose aspirin-induced ulcer cases. The lesion scores of patients taking L-A with H2 receptor antagonists or PPI were significantly lower than those of patients who were taking only L-A (P 〈 0.05).Conclusions : Approximately one-third of hospitalized patients with NSAIDs-induced hemorrhagic ulcer showed an association with L-A. Prospective randomized controlled trials including H2 receptor antagonists are required to establish preventive efforts aimed at L-A-induced gastro-duodenal injury.

Notes: Rotating bending fatigue tests were carried out to investigate the influence of grain sizeon the resistance to crack growth of Ni-base super alloy, Inconel 718, using the materials with grainsizes of about 20, 50,100 and 200 たm, at room temperature. The larger grain size, the smaller crackgrowth rate, though the static strength was decreased with increase in grain size. The growth rate ofa small crack was uniquely determined by the term jana (Small crack growth law), where ja and aare the stress amplitude and the crack length, respectively, and n is a constant. The resistance tocrack growth among materials was evaluated based on the law and showed a good correlation withtensile strength jB, meaning that fatigue life can be predicted by using only j B BB

Notes: Gelation velocity and reaction rate for the acid-catalyzed condensation reaction in the aqueous solution (10-22%) of partially N-methylolcarbamoylethylated polyvinyl alcohol (about 20 mole-% degree of methylolcarbamoylethylation) have been investigated by the falling ball viscosity method and the chemical analysis of methylol groups including the effects of kinds of acid, concentrations of acid and polymer, and temperatures of reaction. For the reciprocal gel point, 1/tg, and the hydrogen ion concentration, [H+], the following equation holds: \documentclass{article}\pagestyle{empty}\begin{document}$ 1/t_g = c[{\rm H}^ +]^\alpha $\end{document} where α and c are constants independent of the kind of acid; also α is independent of temperature and polymer concentration, while c increases with increasing temperature or polymer concentration. The 1/tg is approximately proportional to the concentration of polymer in the range of a concentrated polymer solution above about 15% by weight. From this fact, it is suggested that, in a concentrated polymer solution, the intermolecular crosslinking proceeds predominantly as a bimolecular reaction with respect to methylol groups. Assuming that the increase of the apparent viscosity of the reacting system is mainly due to that of the structural viscosity which should be increased by a bimolecular crosslinking reaction, the following expression was derived for the gelation velocity: \documentclass{article}\pagestyle{empty}\begin{document}$ \eta _0 /(\eta _t - \eta _0) = A(1/i - 1/t_g) $\end{document} in which, \documentclass{article}\pagestyle{empty}\begin{document}$ \begin{array}{*{20}c} {A/t_g = 1 - x_g /a} & {{\rm and}} & {k = x_g /(a^2 A)} \\ \end{array} $\end{document} where η0 and ηt are the apparent viscosities at time 0 and t, respectively, A is a measure of gelation velocity, a is the initial number of methylol groups, xg is the number of crosslinked methylol groups at the gel point, and k is the bimolecular rate constant. The experimental results of viscosity changes have shown a fairly good agreement with the above expression except in the early stage of condensation. The extent of reaction at the gel point (xg) has been estimated to be about 0.03-0.05 regardless of concentration of polymer and acid, kinds of acid, and temperature. Also, it has been observed that the rate constant of reaction is independent of the concentration of polymer and is proportional to the concentration of hydrogen ions. The above expression and estimation have been verified by the chemical analysis of methylol groups in the condensation processes. However, the extent of reaction at the gel point is about ten times that predicted by Flory's theory. This discrepancy may presumably be attributed to the fact that all of the methylol groups on the polymer chains which are coiled, entangled, and strongly solvated prior to the crosslinking are not equally reactive sterically and a certain extent of intramolecular crosslinking occurs. The activation energy of reaction has been estimated to be about 21 kcal./mole.

Notes: The effect of polymer dilution on the acid-catalyzed gelation of partially N-methylolcarbamoylethylated polyvinyl alcohol has been studied viscometrically and chemically. The result that the higher the degree of dilution the greater the extent of reaction at gelation, especially in the polymer concentration below 15% by weight, indicates that a certain increase of intramolecular crosslinking with dilution occurs. However, sufficient agreement with Kilb's theory could not be found. Also, even when the extent of reaction at gelation was extrapolated to infinite concentration of polymer, it was far greater than that obtained from Flory's theory. The discrepancy may presumably be attributed to the fact that in addition to the intramolecular crosslinking, all the methylol groups on the polymer chains which are coiled, entangled, and strongly solvated prior to crosslinking are not equally reactive sterically.