Numerical simulation of strain localization and damage evolution in large plastic deformation using mixed finite element method

An investigation of computer simulation is presented to analyze the effectsof strain localization and damage evolution in large plastic deformation. The simulation is carriedout by using an elastic-plastic-damage coupling finite element program that is developed based onthe concept of mixed interpolation of displacement/pressure. This program has been incorporated intoa damage mechanics model as well as the corresponding damage criterion. To illustrate theperformance of the proposed approach, a typical strain localization problem has been simulated. Theresults show that the proposed approach is of good capability to capture strain localization andpredict the damage evolution.

Breathing Intolerance Index in COPD and Obesity: A Comparative Observational Study

Background: The breathing intolerance index, BIT, a noninvasive derivation of the tension-time index of respiratory muscles, has been recently used to evaluate patients with respect to their need for noninvasive ventilation. Comparing the BIT index in different disorders with mild to moderate respiratory impairment, such as COPD and obesity, would be useful in determining differences in threshold for respiratory muscle fatigue amongst cohorts. Objectives: The purpose of this study was to compare control of ventilation and BIT in individuals with obesity, chronic obstructive pulmonary disease (COPD), and control subjects free of cardiorespiratory disorders. Because change in posture can alter respiratory load and control of ventilation, variables were assessed in two postures. Methods: We assessed 142 subjects consisting of 81 with obesity, 42 with COPD, and 19 non-smoking healthy adults. All subjects underwent evaluation of pulmonary function, control of ventilation and BIT index [(Ti/Ttot) × (Vt/FVC)] in seated and supine postures. Findings: BIT index was significantly greater in seated posture in all 3 cohorts due primarily to an increase in Vt in this position. BIT index was similar in value amongst cohorts in both postures, but tended to be higher in patients with obesity and COPD. Conclusion: While BIT index is higher in seated posture, and tends to be higher in patients with obesity and COPD as compared to control subjects, discrimination between cohorts is not found in our study because of small inter-group variations of respiratory function amongst cohorts. Thus, in clinically stable patients whose vital capacities are mild to moderately reduced, the BIT index alone cannot be recommended as a predictive guide for initiating assisted ventilation for respiratory failure. Nevertheless, because it is easy to perform, and is comfortably tolerated by patients, its potential usefulness may be in periodic measurements to monitor its increase as respiratory reserve declines.

Potential therapeutic effects of dipyridamole in the severely ill patients with COVID-19

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection can cause acute respiratory distress syndrome,hypercoagulability,hypertension,and multiorgan dysfunction.Effective antivirals with safe clinical profile are urgently needed to improve the overall prognosis.In an analysis of a randomly collected cohort of 124 patients with COVID-19,we found that hypercoagulability as indicated by elevated concentrations of D-dimers was associated with disease severity.By virtual screening of a U.S.FDA approved drug library,we identified an anticoagulation agent dipyridamole(DIP)in silico,which suppressed SARS-CoV-2 replication in vitro.In a proof-of-concept trial involving 31 patients with COVID-19,DIP supplementation was associated with significantly decreased concentrations of D-dimers(P<0.05),increased lymphocyte and platelet recovery in the circulation,and markedly improved clinical outcomes in comparison to the control patients.In particular,all 8 of the DIP-treated severely ill patients showed remarkable improvement:7 patients(87.5%)achieved clinical cure and were discharged from the hospitals while the remaining 1 patient(12.5%)was in clinical remission.