A performance degradation model of nitrile butadiene rubber (NBR) O-rings for hydrogen permeation effects under high-pressure.

The integration of molecular chain changes on a microscopic scale to achieve macroscopic performance is crucial in degradation processes concerning O-ring seals. Nonetheless, a comprehensive and compelling mathematical model that can describe molecular chains' material properties and macroscopic material properties simultaneously for O-rings under high-pressure conditions is yet to be established. In this paper, we propose a degradation model based on viscoelasticity and molecular chain statistics for hydrogen permeation. The proposed model aims to establish the relationship between the material molecular chains and macroscopic material properties, with a primary focus on accurately recognizing the performance degradation process of rubber sealing rings. We verify the model's reliability through uniaxial tensile strength experiments and high-pressure hydrogen immersion experiments, respectively. Predictions of the model exhibit favorable conformity with the experimental data concerning the above phenomena. Furthermore, we derive the number of molecular chains and maximum strain of the degradation process. Based on the similarity of the degradation process's descent, it is plausible to speculate that NBR properties' degradation can be characterized by the average number of molecular chains.

Bio-Inspired Fault Diagnosis for Aircraft Fuel Pumps Using a Cloud-Edge System.

The fuel pump serves as the central component of the aircraft fuel system, necessitating real-time data acquisition for monitoring purposes. As the number of sensors increases, there is a substantial rise in data volume, leading to a simultaneous increase in computational processing for traditional Prognostics and Health Management methods while computational efficiency decreases. In response to this challenge, a novel health monitoring approach for aircraft fuel pumps is proposed based on the collaborative utilization of cloud-edge resources. This approach enables efficient cooperation among the sensor side, edge side, and cloud side to achieve timely fault warnings and accurate fault classification for fuel pumps. Within this method, anomaly judgment tasks are allocated to the edge side, and an anomaly judgment method that integrates the 3σ threshold and "3/5 strategy" is devised. Additionally, a fault diagnosis algorithm, founded on a convolutional auto-encoder, is formulated in the cloud to discern various fault types and severities. Comparative results demonstrate that, in contrast to long short-term memory networks, convolutional neural networks, extreme learning machines, and support vector machines, the proposed method yields improvements in accuracy of 4.35%, 6.40%, 17.65%, and 19.35%, respectively. Consequently, it is evident that the proposed method exhibits notable efficacy in the condition monitoring of aircraft fuel pumps.

[Necessity and safety of conversion from mycophenolate mofetil to AzA thioprine after renal transplantation].

OBJECTIVE: To investigate the necessity and safety of conversion from mycophenolate mofetil (MMF) to Azathioprine (AzA) in stable renal transplant patients. METHODS: In a randomised open clinical trial, A total of 87 low-risk renal allograft recipients on triple immunosuppressive therapy (prednisone/MMF/cyclosporine) 6 months after transplantation was randomised into two groups: converted (switching MMF to AzA treatment 6 months after transplantation, n = 42) and control (continued MMF treatment, n = 45). Renal function, acute rejection episodes, side effects and related complications were analysed in each group. RESULTS: The outcome (such as event-free graft survival rate and incidence of acute rejection) of treatment after a 12-months follow-up of patients in two groups was similar. Liver lesion and leukocytopenia, most of which was reversible, occurred more frequently in the converted than in the control group. CONCLUSION: Under the special economic atmosphere and medical insurance system of our country, the conversion from MMF to AzA in some renal transplant patients was necessary and safe. Further study is needed to evaluate the long-term outcome of this conversion.

Kidney transplantation at the Chinese People's Liberation Army General Hospital.

Between October 1977 and December 2004, 2,037 kidney transplants were performed in 1,804 patients with ESRD at the Peoples Liberation Army General Hospital Postgraduate Medical School. Overall graft survival rates at one, 5, 10, 15, and 20 years were 91.6%, 79.3%, 64.3%, 53.8%, and 47.6%, respectively. The number of transplants significantly increased during the past decade. One-year patient and graft survival rates have increased from 40% and 35% in the 1970s to 98% and 96% in the 2000s, respectively. Since CSA was introduced to our clinic, one-year graft survival rates have increased from 33% to 93% and the half-lives have significantly improved from 13.1 years to 21.7 years. Also, the graft survival rate for patients on CSA-based triple therapy using MMF was about 18% higher at 5 years than those for patients using AZA (92% vs. 74%, p < 0.001), and 11% higher at 10 years (71% vs. 60%, p < 0.01). Our analysis showed that transplant year, DGF, rejection, immunosuppressive regimen, ABO blood group, and original disease were independent factors impacting on graft survival and poor HLA matching with 5-6 mismatches had an adverse effect on graft survival compared with 1-2 mismatches. Infection, cardio- and cerebral accidents and hepatic failure were the 3 main causes of death in transplant recipients.