ディスプレイ用ガラスにおける圧子押し込み誘起表面残留応力の評価

Residual stress field around a Vickers diamond indentation was studied in three commercial glasses with different strain points (Ts=635°C, 570°C and 511°C, respectively). The basis of the experimental technique is to use cracks from a small indentation as a microprobe to measure the residual stress at a specific point around a large indentation and to study the change of the residual stress by heat treatment. Residual tensile and compressive stresses around a large indentation produced by applying the load of 19.6N were distributed up to a distance of about 400μm from the indentation center. For all specimens, the tensile and compressive stresses were about 10 MPa and -50MPa--30MPa, respectively, at a distance of 200μm from the indentation center. The residual stresses decreased by heat treatment at temperatures as low as 300°C below the strain point and became zero by keeping the indented specimen at temperatures close to the strain point of each glass, for 7.2ks. The resistance to decrease in residual stresses against temperature was in the order Si-B-Al-O(Ts=635°C)>Si-Al-O(Ts=570°C)>Si-Ca-Na-O(Ts=511°C) glass. The results were discussed based on the difference of the mobility of constituent ions and flow of glasses

Noninvasive Positive Pressure Ventilation in Treatment of Non-COPD Related Acute Respiratory Failure Cases

We used Noninvasive Positive Pressure Ventilation (NPPV) in nine patients with acute respiratory failure (ARF), not related to chronic obstructive pulmonary disease (COPD). After separating the nine patients into a hypercapnic group (five patients) and a non-hypercapnic group (four patients), we investigated its effectiveness in physiological improvement and avoiding intubation. Dyspnea, physiological findings and ABG improved rapidly in both groups without serious adverse effects. The intubation avoidance rate was 66.7% (6 of 9) in total, and 80% in the hypercapnic group and 50% in the non-hypercapnic group. The ratio of PaO_2 to FiO_2 (P/F ratio) increased during NPPV in most cases where intubation could be avoided. It is worthwhile to use NPPV as a bridging therapy between O_2 therapy and invasive ventilation in patients with non-COPD related ARF, regardless of the existence of hypercapnia. Careful monitoring of the P/F ratio and complications is needed to make an appropriate decision whether avoiding intubation will be possible or not