The long service life and high reliability of SiC sliding bearings are crucial for the long-term normal operation of aerospace power equipment.In response to the fracture phenomenon observed in the sliding bearing assembly of a certain delivery pump during operation,this paper analyzes the issue from the perspectives of stress characteristics and thermal expansion effects,proposing a structural optimization design method based on temperature coefficient compensation.The research indicates that the primary cause of bearing fracture is the difference in thermal expansion coefficients between the bearing and the metal rotor under elevated temperatures,leading to axial loosening of the bearing.Additionally,the gap between the bearing and the pin,combined with unstable lubrication of the friction pair,exacerbates bearing stalling and pin impact,ultimately causing cracks and localized chipping.By optimizing the bearing structure and employing a rubber pad for torque transmission,this issue has been successfully resolved.The improved structure demonstrated high reliability and stability in bench tests,providing important theoretical and technical references for the design of bearings under similar extreme operating conditions.

Objective To assess the incidence of contrast-induced nephropathy(CIN)in patients with chronic thromboembolic pulmonary hypertension(CTEPH)after receiving balloon pulmonary angioplasty(BPA),and to evaluate the effect of the contrast agents on renal function.Methods A total of 143 CTEPH patients,who received BPA at the China-Japan Friendship Hospital of China from December 2018 to May 2022,were enrolled in this study.The clinical data,hemodynamic indicators,and serum creatinine(SC)concentrations within one week before and 48-72 h after BPA were collected.The estimated glomerular filtration rate(eGFR)was calculated according to the Modification of Diet in Renal Disease(MDRD)formula.The SC concentration and eGFR changes before and after each BPA procedure were compared.The incidence of CIN and its risk factors were evaluated,and the changes in hemodynamics,SC and eGFR after the initial and last time of BPA treatment were analyzed.Results A total of 192 BPA procedures were performed in 115 CTEPH patients,including 88 BPA procedures in males and 103 BPA procedures in females.The mean amount of contrast agent used for each BPA was(145.58±47.26)mL.After BPA,12 patients developed 13 times of CIN,with an incidence of 6.8％.There was no significant differences(P＞0.05)in the baseline characteristics and SC concentration before BPA between CIN patients and non-CIN patients.In terms of the hemodynamic indexes,the mixed venous oxygen saturation(SvO2)in CIN patients was significantly lower than that in non-CIN patients(58.58％±10.38％vs.66.15％±8.02％,P=0.002),and no statistically significant differences(P＞0.05)in the other hemodynamic indexes existed between CIN group and non-CIN group.No statistically significant differences in SC concentration and eGFR existed before and after each BPA procedure.In patients who had received several BPA procedures,significant improvements in the SC[(78.09±18.760)μmol/L vs.(82.26±21.37)μmol/L,P＜0.001]and eGFR[(86.08±21.22)mL/(min·1.73 m2)vs.(82.07±22.05)mL/(min·1.73 m2),P=0.007]was achieved when compared with their baseline values.Conclusion CTEPH patients may develop CIN after receiving BPA treatment.After receiving several BPA treatments the patient's clinical symptoms and hemodynamics can be improved,and the patient's renal function is also significantly improved.

Objective:To investigate the values of two-dimensional and three-dimensional echocardiographic parameters in predicting pulmonary vascular resistance (PVR) in chronic pulmonary thromboembolic pulmonary hypertension (CTEPH).Methods:A total of 141 patients diagnosed with CTEPH in China-Japan Friendship Hospital from November 2015 to December 2022 were included. Two-dimensional echocardiographic indicators reflecting PVR were constructed according to the calculation formula of PVR: echocardiographic estimated systolic pulmonary artery pressure (sPAP Echo)/left ventricular end-diastolic diameter (LVIDd), echocardiographic estimated mean pulmonary artery pressure (mPAP Echo)/LVIDd. sPAP Echo/left ventricular end-diastolic volume (LVEDV), sPAP Echo/left ventricular cardiac output (LVCO) were measured by three-dimensional echocardiography. The correlations between two-dimensional and three-dimensional echocardiographic ratios and invasive PVR were then analyzed using the Spearman correlation method. Using receiver operating characteristic curve analysis, cut-off values for the ratios were generated to identify patients with PVR>1 000 dyn·s -1·cm -5. Pre- and postoperative hemodynamics and echocardiographic data were analyzed, as well as the correlation between the reduction rate of the echocardiographic index and PVR in 54 patients who underwent pulmonary endarterectomy (PEA). Results:sPAP Echo/LVIDd, sPAP Echo/LVEDV and sPAP Echo/LVCO were moderately correlated with PVR( rs=0.62, 0.52, 0.63, both P<0.001). The ratio of sPAP Echo to LVEDV, when greater than or equal to 1.41, had a sensitivity of 0.800 and a specificity of 0.930 for determining PVR >1 000 dyn·s -1·cm -5 (AUC=0.860, P<0.001). Similarly, the ratio of sPAP Echo to LVIDd, when greater than or equal to 2.14, had a sensitivity of 0.647 and a specificity of 0.861 for determining PVR >1000 dyn·s -1·cm -5 (AUC=0.830, P<0.001). The sPAP Echo/LVIDd and mPAP Echo/LVIDd significantly decreased after PEA (both P<0.001). The sPAP Echo/LVIDd and mPAP Echo/LVIDd reduction rate (ΔsPAP Echo/LVIDd and ΔmPAP Echo/LVIDd) were significantly correlated with PVR reduction rate (ΔPVR), respectively ( rs=0.61, 0.63, both P<0.05). Conclusions:Two-dimensional ratio sPAP Echo/LVIDd and three-dimensional ratio sPAP Echo/LVEDV can be used to noninvasively estimate PVR in CTEPH patients. The conventional ratio sPAP Echo/LVIDd is convenient and reproducibly suitable for monitoring the improvement of PVR before and after treatment, and its ratio of 2.14 can predict the significant increase of PVR in CTEPH patients (>1 000 dyn·s -1·cm -5).

Objective:To investigate the safety and efficacy of balloon pulmonary angioplasty (BPA) for residual pulmonary hypertension (PH) of chronic thromboembolic pulmonary hypertension(CTEPH) after pulmonary endarterectomy (PEA).Methods:Patients diagnosed as PH after PEA in China-Japan Friendship Hospital from Oct 2016 to Jun 2022 were included. The indication for BPA was decided on the basis of a consensus of the multi-disciplinary team for all patients with CTEPH. Before treatment, the patient′s exercise tolerance and pulmonary artery flow parameters were evaluated. A comparative analysis of various parameters before BPA treatment and at the last BPA was conducted. 6-min walk distance (6MWD) was analyzed using the paired Wilcoxon test; N-terminal pro-brain natriuretic peptide (NT-proBNP), mixed venous oxygen saturation, mean pulmonary arterial pressure (mPAP), cardiac index (CI) and pulmonary vascular resistance (PVR) were compared using the paired-samples t-test. WHO functional class was compared using McNemar′s test. Results:Twenty patients with a total of 130 vessels underwent 46 sessions of BPA treatment. The postoperative 6-minute walk distance (6MWD) [447 (415, 485) m] showed a significant improvement compared to the preoperative baseline [389 (335, 470) m] ( Z=6.52, P<0.05), Postoperative mixed venous oxygen saturation (72.0%±1.9%) showed a significant improvement compared to the preoperative levels (64.0%±2.7%) ( t=2.14, P<0.05).Postoperatively, plasma NT-proBNP [(351.9±129.9) pg/ml], mPAP [(24.2±1.9) mmHg], and PVR [(3.0±1.4) WU] significantly decreased compared to preoperative levels [(982.5±426.2) pg/ml, (33±2.1) mmHg, (8.0±1.6) WU)] ( t=3.38, 1.22, 2.10, P<0.05 for all). Postoperatively, there was a significant improvement in WHO functional class (Ⅰ，Ⅱ，Ⅲ，Ⅳ: 14, 4, 2, 0 cases) compared to preoperative status (Ⅰ，Ⅱ，Ⅲ，Ⅳ: 0, 13, 5, 2 cases) ( χ2=20.17, P<0.05). Four cases of pulmonary artery dissection and one episode of hemoptysis occurred postoperatively, with no other complications reported. Conclusions:BPA can significantly improve exercise tolerance and hemodynamic parameters for residual PH after PEA. BPA is a relatively safe and effective treatment for residual PH after PEA.

Objective:To evaluate the role of neuronal nitric oxide synthase (nNOS)-nitric oxide synthase 1 adaptor protein (NOS1AP) coupling in remifentanil-induced hyperalgesia in rats.Methods:Forty clean-grade healthy adult male Sprague-Dawley rats, weighing 240-260 g, aged 2-3 months, were divided into 4 groups ( n=10 each) using a random number table method: control group (group C), remifentanil group (group R), nNOS-NOS1AP inhibitor ZLc002 group (group C+ Z) and remifentanil + ZLc002 group (group R+ Z). Normal saline was intravenously infused at a rate of 0.1 ml·kg -1·min -1 for 60 min in C group. Remifentanil was intravenously infused at a rate of 1.0 μg·kg -1·min -1 for 60 min in R group. ZLc002 10 mg/kg was intraperitoneally injected for 3 consecutive days, and then normal saline 0.1 ml·kg -1·min -1 and remifentanil 1.0 μg·kg -1·min -1 were intravenously infused for 60 min in C+ Z group and R+ Z group. The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured at 24 h before intravenous infusion and 6, 24 and 48 h after intravenous infusion (T 0-3). All the rats were sacrificed after the last measurement of pain thresholds, and the L 4-6 segments of the spinal cord were removed for determination of the expression of nNOS, NOS1AP and Dexamethasone-induced Ras-related protein 1 (Dexras1) protein and mRNA using the real-time polymerase chain reaction. Nitrosylated proteins were extracted by biotin conversion for determination of the expression of nNOS, NOS1AP and total and nitrosylated Dexras1 (by Western blot) and co-expression of nNOS-NOS1AP (by co-immunoprecipitation). The content of NO in the spinal cord was measured. Results:Compared with group C, the MWT was significantly decreased, and the TWL was shortened at T 1-3, the expression of nNOS and NOS1AP protein and mRNA was up-regulated, the co-expression of nNOS-NOS1AP and NO production were increased, and the expression of nitrosylated Dexras1 was up-regulated in group R ( P<0.05), and no significant change was found in each aforementioned parameter in group C+ Z ( P>0.05). Compared with group R, the MWT was significantly increased, and the TWL was prolonged at T 1-3, the co-expression of nNOS-NOS1AP and NO production were decreased, the expression of nitrosylated Dexras1 was down-regulated ( P<0.05), and no significant change was found in the expression of nNOS and NOS1AP protein and mRNA in group R+ Z ( P>0.05). There were no significant differences in total Dexras1 protein and mRNA expression among the four groups ( P>0.05). Conclusions:The mechanism by which remifentanil induces hyperalgesia may be related to up-regulating the expression of nNOS and NOS1AP in the spinal cord, promoting interaction between nNOS and NOS1AP and mediating NO generation and Dexras1 nitrosylation modification in rats.

A LAMP-Taqman rapid detection system for porcine pseudorabies virus(PRV)was de-veloped based on LAMP and quantitative PCR.LAMP primers were designed for PRV conserved sequences,and the loop primer modified by the fluorescent quenching group was used as the Taq-man probe.The composition optimization,specificity,sensitivity and repeatability of the LAMP-Taqman system were tested using positive samples and recombinant plasmid as templates.Thirty-eight samples of pork swabs were tested with the commercial LAMP detection kit in parallel to verify the actual detection effect of the LAMP-Taqman detection system.The results showed that the optimal final concentration of each component was as follows:PRV-FIP/BIP 0.8 μmol/L,Bst DNA polymerase 0.7 U/μL,Taq DNA polymerase 0.24 U/μL,dNTPs 1.6 mmol/L,MgSO47.2 mmol/L.This system had good specificity and did not cross-react with other virus samples.The linear correlation coefficient of gradient samples was 0.995,the coefficient of variation of repeatable tests was less than 3.000％,and the minimum detection limit could reach 2.81 ×102 copies/μL.The test results of the actual swab samples were consistent with the commercial isothermal fluores-cence detection reagents.In conclusion,the PRV detection system established by LAMP-Taqman method in this study is specific,sensitive,stable and accurate,and is a reliable technical method suitable for the accurate detection of porcine PRV.

Objective:To investigate the effect of low-dose ketamine on neuroinflammation and microcirculation in mice with traumatic brain injury (TBI).Methods:Sixty adult male C57BL/6 mice, weighing 22-28 g, were randomly divided into sham-operated group, TBI group, Sham+ketamine group, and TBI+ketamine group ( n=15). A controlled cortical impingement (CCI) method was used to establish TBI models in the later 2 groups. Sham+ketamine group and TBI+ketamine group were intraperitoneally injected with 30 mg/kg ketamine once daily for 3 d at 30 min after TBI; sham-operated group and TBI group were intraperitoneally injected same amount of saline at the same time points. Cerebral cortical blood flow in 6 mice from each group was measured by laser speckle contrast imaging (LSCI) before, immediately after, 30 min after, 1 d after and 3 d after modeling, respectively. Three d after modeling, immunohistochemical staining and immunofluorescent double label staining were used to detect the nuclear translocation of microglia markers, ionized calcin-antibody-1 (Iba-1) and nuclear factor (NF)-κB p65 in damaged cortical brain tissues in 6 mice from each group. The remaining 3 mice in each group were sacrificed and tissue plasma was extracted 3 d after modeling; levels of NF-κB p65, phosphorylated (p)-NF-κB p65, p-IκB and inducible nitric oxide synthase (iNOS) in cortical brain tissues were detected by Western blotting. Expressions of tumor necrosis factor-α (TNF-α), interleukin-1-β (IL-1β) and interleukin-6 (IL-6), iNOS, reactive oxygen species (ROS) and reactive nitrogen species (RNS) in cortical brain tissues were detected by ELISA. Results:LSCI indicated that, 3 d after modeling, relative blood flow in local cerebral microcirculation of TBI+ketamine group was significantly increased compared with that of TBI group ( P<0.05). Immunohistochemical staining indicated that compared with the sham-operated group and Sham+ketamine group, the TBI group and TBI+ketamine group had significantly increased number of Iba-1 positive cells in the cerebral cortex ( P<0.05); compared with the TBI group, the TBI+ketamine group had significantly decreased number of Iba-1 positive cells ( P<0.05). ELISA indicated that compared with the sham-operated group and Sham+ketamine group, the TBI group and TBI+ketamine group had significantly increased expressions of TNF-α, IL-1β, IL-6, iNOS, ROS and RNS in damaged cortical brain tissues ( P<0.05); compared with the TBI group, the TBI+ ketamine group had significantly decreased expressions of TNF-α, IL-1β, IL-6, iNOS, ROS and RNS in damaged cortical brain tissues ( P<0.05). Immunofluorescent double label staining indicated obviously inhibited NF-κB p65 nuclear translocation in TBI+ketamine group when it was compared with TBI group. Western blotting indicated that compared with the sham-operated group and Sham+ketamine group, the TBI+ketamine group had significantly increased iNOS, NF-κB p65, p-NF-κB p65 and P-IκB protein expressions in damaged cortical brain tissues ( P<0.05); compared with the TBI group, the TBI+ketamine group had significantly decreased protein expressions of iNOS, NF-κB p65, p-NF-κB p65 and p-IκB in damaged cortical brain tissues ( P<0.05). Conclusion:Low-dose ketamine reduces neuroinflammation and improves cerebral microcirculatory blood flow after open TBI, whose mechanism may be related to inhibition of microglia NF-κB/iNOS pathway.

Objective:To understand the epidemiological characteristics of human respiratory syncytial virus (HRSV) among acute respiratory infection (ARI) cases in 16 provinces of China from 2009 to 2023.Methods:The data of this study were collected from the ARI surveillance data from 16 provinces in China from 2009 to 2023, with a total of 28 278 ARI cases included in the study. The clinical specimens from ARI cases were screened for HRSV nucleic acid from 2009 to 2023, and differences in virus detection rates among cases of different age groups, regions, and months were analyzed.Results:A total of 28 278 ARI cases were enrolled from January 2009 to September 2023. The age of the cases ranged from<1 month to 112 years, and the age M ( Q1, Q3) was 3 years (1 year, 9 years). Among them, 3 062 cases were positive for HRSV nucleic acid, with a total detection rate of 10.83%. From 2009 to 2019, the detection rate of HRSV was 9.33%, and the virus was mainly prevalent in winter and spring. During the Corona Virus Disease 2019 (COVID-19) pandemic, the detection rate of HRSV fluctuated between 6.32% and 18.67%. There was no traditional winter epidemic peak of HRSV from the end of 2022 to the beginning of 2023, and an anti-seasonal epidemic of HRSV occurred from April to May 2023. About 87.95% (2 693/3 062) of positive cases were children under 5 years old, and the difference in the detection rate of HRSV among different age groups was statistically significant ( P<0.001), showing a decreasing trend of HRSV detection rate with the increase of age ( P<0.001). Among them, the HRSV detection rate (25.69%) was highest in children under 6 months. Compared with 2009-2019, the ranking of HRSV detection rates in different age groups changed from high to low between 2020 and 2023, with the age M (Q1, Q3) of HRSV positive cases increasing from 1 year (6 months, 3 years) to 2 years (11 months, 3 years). Conclusion:Through 15 years of continuous HRSV surveillance analysis, children under 5 years old, especially infants under 6 months old, are the main high-risk population for HRSV infection. During the COVID-19 pandemic, the prevalence and patterns of HRSV in China have changed.

Background::Acute pulmonary embolism (APE) is a fatal cardiovascular disease, yet missed diagnosis and misdiagnosis often occur due to non-specific symptoms and signs. A simple, objective technique will help clinicians make a quick and precise diagnosis. In population studies, machine learning (ML) plays a critical role in characterizing cardiovascular risks, predicting outcomes, and identifying biomarkers. This work sought to develop an ML model for helping APE diagnosis and compare it against current clinical probability assessment models.Methods::This is a single-center retrospective study. Patients with suspected APE were continuously enrolled and randomly divided into two groups including training and testing sets. A total of 8 ML models, including random forest (RF), Na?ve Bayes, decision tree, K-nearest neighbors, logistic regression, multi-layer perceptron, support vector machine, and gradient boosting decision tree were developed based on the training set to diagnose APE. Thereafter, the model with the best diagnostic performance was selected and evaluated against the current clinical assessment strategies, including the Wells score, revised Geneva score, and Years algorithm. Eventually, the ML model was internally validated to assess the diagnostic performance using receiver operating characteristic (ROC) analysis.Results::The ML models were constructed using eight clinical features, including D-dimer, cardiac troponin T (cTNT), arterial oxygen saturation, heart rate, chest pain, lower limb pain, hemoptysis, and chronic heart failure. Among eight ML models, the RF model achieved the best performance with the highest area under the curve (AUC) (AUC = 0.774). Compared to the current clinical assessment strategies, the RF model outperformed the Wells score ( P = 0.030) and was not inferior to any other clinical probability assessment strategy. The AUC of the RF model for diagnosing APE onset in internal validation set was 0.726. Conclusions::Based on RF algorithm, a novel prediction model was finally constructed for APE diagnosis. When compared to the current clinical assessment strategies, the RF model achieved better diagnostic efficacy and accuracy. Therefore, the ML algorithm can be a useful tool in assisting with the diagnosis of APE.

Objective:To understand the epidemiological characteristics of human respiratory syncytial virus (HRSV) among acute respiratory infection (ARI) cases in 16 provinces of China from 2009 to 2023.Methods:The data of this study were collected from the ARI surveillance data from 16 provinces in China from 2009 to 2023, with a total of 28 278 ARI cases included in the study. The clinical specimens from ARI cases were screened for HRSV nucleic acid from 2009 to 2023, and differences in virus detection rates among cases of different age groups, regions, and months were analyzed.Results:A total of 28 278 ARI cases were enrolled from January 2009 to September 2023. The age of the cases ranged from<1 month to 112 years, and the age M ( Q1, Q3) was 3 years (1 year, 9 years). Among them, 3 062 cases were positive for HRSV nucleic acid, with a total detection rate of 10.83%. From 2009 to 2019, the detection rate of HRSV was 9.33%, and the virus was mainly prevalent in winter and spring. During the Corona Virus Disease 2019 (COVID-19) pandemic, the detection rate of HRSV fluctuated between 6.32% and 18.67%. There was no traditional winter epidemic peak of HRSV from the end of 2022 to the beginning of 2023, and an anti-seasonal epidemic of HRSV occurred from April to May 2023. About 87.95% (2 693/3 062) of positive cases were children under 5 years old, and the difference in the detection rate of HRSV among different age groups was statistically significant ( P<0.001), showing a decreasing trend of HRSV detection rate with the increase of age ( P<0.001). Among them, the HRSV detection rate (25.69%) was highest in children under 6 months. Compared with 2009-2019, the ranking of HRSV detection rates in different age groups changed from high to low between 2020 and 2023, with the age M (Q1, Q3) of HRSV positive cases increasing from 1 year (6 months, 3 years) to 2 years (11 months, 3 years). Conclusion:Through 15 years of continuous HRSV surveillance analysis, children under 5 years old, especially infants under 6 months old, are the main high-risk population for HRSV infection. During the COVID-19 pandemic, the prevalence and patterns of HRSV in China have changed.