Copyright (c)JCPDS-International Centre for Diffraction Data

ABSTRACT This paper describes the effect of renitriding for hot work die steel. We noticed a decrease of compressive residual stress on the nitrided die surface during thermal fatigue process. X-ray stress measurement was used to detect the decomposition of nitride layer on hot work die steel (H13). As a result, compressive residual stress decreased gradually during the thermal fatigue test, almost restoring to the pre-test level by renitriding. The number of cracks decreased with the frequency of test by surface removal effect of shot peening while renitriding. Comparing the renitrided specimen with non renitrided specimen (single nitride), the number of cracks had decreased. 1.INTRODUCTION On the surface of hot work die, such as die-casting die, heat cycles are applied during the operation. Then, the cracks occurred due to thermal stresses caused by thermal cycles. To extend die-casting die life, nitriding is often applied to the die surface 1) . Even with nitriding, the nitride layer is damaged by heat during the die-casting operation. Thus, if renitriding will be available with the detecting damaged layer quantitatively, extension of die life can be expected. On the other hand, high compressive residual stress about -900MPa is caused on the surface of hot work die steel (AISI-H13) by nitriding. And the reheating decreases the residual stress 2) . We noticed the compressive residual stress, and tried to detect decomposition of nitride layer in thermal fatigue process by X-ray stress measurement. And repair effect of nitride layer by renitriding with shot peening was investigated. During the thermal fatigue test, renitriding was applied several times and changes of residual stress and half-value breadth were measured. After the test, distribution of residual stress, maximum crack length and number of cracks were measured

Sudden infant death due to mechanical asphyxia caused by a cervical ectopic thymus—An autopsy case

The 7-month-old girl was left in a nursery until following morning. About 3 h after being given milk, she was found dead in a right lateral supine position. There was no external evidence of injury to suggest a maltreatment. Hemorrhages were present in the accessory respiratory muscles, but the most notable findings were masses on either side of the trachea and immediately inferior to the thyroid gland. Both of masses were in continuity with the intrathoracic thymus. Histopathologically, the masses showed normal thymic structure and collagen fibers on the left side of the trachea showed metachromasia on Masson’s staining. There were no remarkable findings in organs except for congestion. The cause of death was determined to be mechanical asphyxia due to tracheal compression by the cervical ectopic thymus. Hemorrhage in the accessory respiratory muscle was considered to be caused by effortful breathing during the process of asphyxia. The metachromasia of Masson's stain on the trachea may be due to the same mechanism as a “compression mark reaction”, and may be useful in proving compression by the ectopic thymus. We consider that chronic compression of the trachea led to the tracheomalacia, which enabled the final lethal compression when lying in a right lateral supine position. An ectopic thymus is caused by a failure of descent of the embryonic thymic tissue into the thoracic cavity at the appropriate developmental stage and is generally asymptomatic. However, the cervical ectopic thymus should be considered in the diagnosis of a cause of sudden infant death

National trends in the outcomes of subarachnoid haemorrhage and the prognostic influence of stroke centre capability in Japan: retrospective cohort study

Objectives To examine the national, 6-year trends in in-hospital clinical outcomes of patients with subarachnoid haemorrhage (SAH) who underwent clipping or coiling and the prognostic influence of temporal trends in the Comprehensive Stroke Center (CSC) capabilities on patient outcomes in Japan.Design Retrospective study.Setting Six hundred and thirty-one primary care institutions in Japan.Participants Forty-five thousand and eleven patients with SAH who were urgently hospitalised, identified using the J-ASPECT Diagnosis Procedure Combination database.Primary and secondary outcome measures Annual number of patients with SAH who remained untreated, or who received clipping or coiling, in-hospital mortality and poor functional outcomes (modified Rankin Scale: 3–6) at discharge. Each CSC was assessed using a validated scoring system (CSC score: 1–25 points).Results In the overall cohort, in-hospital mortality decreased (year for trend, OR (95% CI): 0.97 (0.96 to 0.99)), while the proportion of poor functional outcomes remained unchanged (1.00 (0.98 to 1.02)). The proportion of patients who underwent clipping gradually decreased from 46.6% to 38.5%, while that of those who received coiling and those left untreated gradually increased from 16.9% to 22.6% and 35.4% to 38%, respectively. In-hospital mortality of coiled (0.94 (0.89 to 0.98)) and untreated (0.93 (0.90 to 0.96)) patients decreased, whereas that of clipped patients remained stable. CSC score improvement was associated with increased use of coiling (per 1-point increase, 1.14 (1.08 to 1.20)) but not with short-term patient outcomes regardless of treatment modality.Conclusions The 6-year trends indicated lower in-hospital mortality for patients with SAH (attributable to better outcomes), increased use of coiling and multidisciplinary care for untreated patients. Further increasing CSC capabilities may improve overall outcomes, mainly by increasing the use of coiling. Additional studies are necessary to determine the effect of confounders such as aneurysm complexity on outcomes of clipped patients in the modern endovascular era