Effects of intermittent loading time and stress ratio on dwell fatigue behavior of titanium alloy Ti-6Al-4V ELI used in deep-sea submersibles

Different components of deep-sea submersibles,such as the pressure hull,are usually subjected to intermittent loading,dwell loading,and unloading during service.Therefore,for the design and reliability assessment of structural parts under dwell fatigue loading,understanding the effects of intermittent loading time on dwell fatigue behavior of the alloys is essential.In this study,the effects of the intermittent loading time and stress ratio on dwell fatigue behavior of the titanium alloy Ti-6 Al-4 V ELI were investigated.Results suggest that the dwell fatigue failure modes of Ti-6 Al-4 V ELI can be classified into three types,i.e.,fatigue failure mode,ductile failure mode,and mixed failure mode.The intermittent loading time does not affect the dwell fatigue behavior,whereas the stress ratio significantly affects the dwell fatigue life and dwell fatigue mechanism.The dwell fatigue life increases with an increase in the stress ratio for the same maximum stress,and specimens with a negative stress ratio tend to undergo ductile failure.The mechanism of dwell fatigue of titanium alloys is attribute to an increase in the plastic strain caused by the part of the dwell loading,thereby resulting in an increase in the actual stress of the specimens during the subsequent loading cycles and aiding the growth of the formed crack or damage,along with the local plastic strain or damage induced by the part of the fatigue load promoting the cumulative plastic strain during the dwell fatigue process.The interaction between dwell loading and fatigue loading accelerates specimen failure,in contrast to the case for individual creep or fatigue loading alone.The dwell fatigue life and cumulative maximum strain during the first loading cycle could be correlated by a linear relationship on the log–log scale.This relationship can be used to evaluate the dwell fatigue life of Ti alloys with the maximum stress dwell.

NATURAL HISTORY OBSERVATION FOR ESOPHAGEAL AND CARDIA PRECURSORS BY REPETITIVE ENDOSCOPIC SCREENING OF 301 SUBJECTS IN SHEXIAN

OBJECTIVE To investigate the natural history of fast developing esophageal and cardia precursors.METHODS Repetitive endoscopic screenings were performed among 40-69-year-olds in the high-incidence areas for esophageal cancer in Shexian. RESULTS The initial diagnosis and the lag-time for 7 subsequently identified severe dysplasia （SD） subjects were as follows： in one subject 13 months after a baseline diagnosis of normal epithelium, in another subject 7 months after a baseline diagnosis of base cell hyperplasia （BCH）, in four subjects 3, 4, 4, and 10.5 months after baseline diagnosis of mild dysplasia （mD）, and in one subject 12.5 months after a baseline diagnosis of moderate dysplasia （MD）. The initial diagnosis and the lag-time for 6 subsequently identified carcinomas in situ or intramucosal carcinoma cases were： in one case 48 months after a baseline diagnosis of mD, in 2 cases 4 and 13 months after baseline diagnoses of MD, and in the other 3 cases 3.5, 9, and 17.5 months after baseline diagnoses of SD. The initial diagnosis and lag-time for 3 subsequently identified invasive cancer cases, were： in one case 50 months after a baseline diagnosis of MD, in 2 cases 14 and 19 months after baseline diagnoses of SD. In addition, during a 4-year-follow-up of 18 subjects after endoscopic mucosa resection, 9 of them were found to have developed precursors again at other sites, and also additional findings were obtained for 11 of the 16 dysplasia cases by repetitive biopsy in less than 2 months after the initial endoscopy. CONCLUSION A 5-year screening interval for BCH and mD, and a 3-year interval for MD may be too long for the fast developing precursors. Periodic screenings with shorter intervals should be considered to control the number of interval cases due to fast development, multifocal carcinogenesis, and false negative results inherent in one-time endoscopic biopsy sampling.

The Progress of the Study on the Effect of Vibration Training on Muscle Strength Exercise

Vibration training is more and more extensively applied to the field of strength training. It, as a beneficial supplement to the traditional strength, is able to improve specific strength or the strength of weak positions, for the purpose of achieving the muscle strength development in an all-round way. In this paper, the anatomy, physiology, and biomechanics foundations for vibration training to increase muscle strength are mainly analyzed, and then the principle of vibration training to increase muscle strength is further expounded, and also the increase of muscle strength is discussed from the aspects such as vibration frequency, vibration amplitude, vibration posture, vibration intermittent time, and vibration mode, so as to clarify the domestic and foreign progress of the study on vibration training.

Implications of clinical pathway reform on pharmaceutical costs at a hospital in Qingdao city

To study on the effect of clinical pathway （CP） on controlling pharmaceutical costs, we selected complex, chronic, non-communicable diseases, including cerebral infarction, cerebral hemorrhage, transient ischemic attack, and chronic obstructive pulmonary disease, as diseases to implement clinical pathways at a tertiary hospital in Qingdao. We then conducted intermittent time series analysis on pharmaceutical costs. After the implementation of clinical pathway, overall pharmaceutical costs of patients with transient ischemic attack reduced significantly. The effect was not significant for cerebral hemorrhage patients. The implementation of clinical pathway has a desirable outcome on controlling pharmaceutical costs.