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Your search keyword '"Cai, Yuhang"' showing total 4 results
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4 results on '"Cai, Yuhang"'

1. Impedance Study of Thermal Barrier Coating Deterioration in Gas Turbines

Author

DONG Xiaoke, ZHANG Hao, TAN Yu, CAI Yuhang, YUAN Weiming, LIANG Kexin, ZHANG Shenghan

Subjects
ac impedance； thermal barrier coating； actual machine temperature； deterioration process； nondestructive testing, Materials of engineering and construction. Mechanics of materials, TA401-492, Technology
Abstract

Some inherent characteristics of thermal barrier coatings (TBC), such as porosity, thinner thickness and relatively high electrical resistivity, limit the application of traditional room temperature non-destructive testing techniques.Therefore, a method for monitoring oxide growth in thermal barrier coatings using impedance spectroscopy in high-temperature environments was proposed.Based on the principle of impedance spectroscopy test, the growth information of oxides in thermal barrier coatings was obtained by analyzing the response of AC impedance in different frequency domains and phase angle information, and the prediction model was constructed based on the micromorphology of SEM.Results showed that after oxidizing at 1 000 ℃for different times, a dense dark thermally grown oxide (TGO) layer was formed between the ceramic layer and the adhesive layer, and its thickness increased with the prolongation of oxidation time, exhibiting a non-linear relationship.As the oxidation time prolonged, the composition of the TGO layer transitions from Al2O3 in the early stage of oxidation to a mixed oxide of Al2O3 (mainly), Cr2O3, CoO and NiO.Furthermore, the relationship between the resistance of the TGO layer and the oxidation time was constructed by establishing an appropriate circuit model to fit the impedance spectrum data, which confirmed the feasibility of non-destructive testing using impedance testing technology in the process of high-temperature degradation of thermal barrier coatings.

Published
2024
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2. In-situ zircon U-Pb dating method by LA-ICP-MS and discussions on the effect of different beam spot diameters on the dating results

Author

WANG Sen, ZHANG Shuanhong, ZHANG Qiqi, LIANG Xia, KONG Linghao, HU Guohui, WANG Kai, WANG Hongyu, and CAI Yuhang

Subjects
la-icp-ms, zircon, u-pb dating, trace element, Geology, QE1-996.5
Abstract

By using the newly introduced GeoLas HD 193 nm ArF excimer laser ablation system and the Agilent 7900 quadrupole inductively coupled plasma mass spectrometer (ICP-MS) in the Key Laboratory of Paleomagnetism and Tectonic Reconstruction at the Institute of Geomechanics, we successfully established the in-situ zircon U-Pb dating method and trace element analytical method by LA-ICP-MS. U-Pb dating experiments were carried out on Plešovice, Temora1 and Qinghu zircons under the experimental conditions of 32 μm beam spot diameter, 5.0 J/cm2 energy density and 5 Hz denudation frequency using the standard zircon 91500 as the external standard. The ideal age results are consistent with their recommended values, and the measured U-Pb ages for Plešovice zircon remain stable in different periods. Meanwhile, a comparative study of the U-Pb dating results in different laboratories was carried out on an unknown sample 11-5, and the dating results are consistent with that obtained in the State Key Laboratory of Geological Processes and Mineral Resources at China University of Geosciences (Wuhan) within analytical error. Trace elements in zircon standard 91500 and glass standard NIST SRM 612 were analyzed by using NIST SRM 610 as an external standard and 29Si as an internal standard, and the measured values are consistent with the recommended values of trace element contents. In addition, the influence of different beam spot diameters on the zircon U-Pb age results was explored by using the Plešovice zircon as an example. The results show that a denudation diameter of 16~44 μm can obtain reliable zircon U-Pb ages similar to the recommended age, and under the same energy density and denudation frequency conditions, U-Pb ages obtained by using 32~44 μm beam spot diameters are more accurate than those obtained by 16~24 μm beam spot diameters.

Published
2022
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3. Analysis of risk factors and clinical prognosis of acute kidney injury early after lung transplantation

Author

Chen Ao, Lian Qiaoyan, Zhang Jianheng, Xu Xin, Wei Bing, Cai Yuhang, Huang Danxia, He Jianxing, and Ju Chunrong

Subjects
tacrolimus (tac), mean arterial pressure (map), estimated glomerular filtration rate, urogenital system, lcsh:R, lung transplantation, lcsh:Medicine, acute kidney injury (aki), urologic and male genital diseases, continuous renal replacement therapy (crrt), intensive care unit, female genital diseases and pregnancy complications, serum creatinine
Abstract

Objective To analyze the risk factors and clinical prognosis of acute kidney injury (AKI) early after lung transplantation. Methods Clinical data of 155 recipients undergoing lung transplantation or combined heart-lung transplantation were retrospectively analyzed, and they were divided into the AKI group (n=104) and non-AKI group (n=51) according to the 2012 Kidney Disease: Improving Global Outcomes Clinical Practice Guideline. The incidence of AKI early after lung transplantation was summarized. The main indexes of recipients were collected. The risk factors of the occurrence of AKI early after lung transplantation were subjected to univariate and multivariate analysis. The clinical prognosis of lung transplant recipients was evaluated and the survival curve was delineated. Results The incidence of AKI early after lung transplantation was 67.1%(104/155), including 47 recipients with stage 1 AKI, 34 recipients with stage2 AKI and 23 recipients with stage 3 AKI, respectively. Sixteen recipients required continuous renal replacement therapy (CRRT) early after lung transplantation. Preoperative complication with diabetes mellitus, preoperative complication with pulmonary hypertension, intraoperative mean arterial pressure (MAP) < 60 mmHg, intraoperative massive blood transfusion, and treatment with excessive therapeutic concentration of tacrolimus (Tac) within postoperative 1 week were the independent risk factors for the occurrence of AKI early after lung transplantation. Up to the end of follow-up, 66 recipients (42.6%) died, including 50 recipients in the AKI group and 16 recipients in the non-AKI group. The cumulative survival rate in the AKI group was significantly lower than that in the non-AKI group (40% vs. 66%, P < 0.05). With the increase of AKI severity, the cumulative survival rate of lung transplant recipients was decreased. Conclusions AKI develops early after lung transplantation with high incidence and poor clinical prognosis. Preoperative complication with diabetes mellitus and pulmonary hypertension, intraoperative MAP < 60 mmHg and massive blood transfusion, and treatment with excessive therapeutic concentration of Tac within postoperative 1 week are the independent risk factors for the occurrence of AKI early after lung transplantation.

Published
2021

4. Analysis on dynamic changes of T lymphocyte subsets in recipients with stable graft status after lung transplantation

Author

Lian Qiaoyan, Chen Ao, Xu Xin, Wei Bing, Cai Yuhang, Huang Danxia, He Jianxing, and Ju Chunrong

Subjects
immunosuppressant, lcsh:R, lung transplantation, lcsh:Medicine, t lymphocyte subset, cd8, rejection, cd3, infection, cd4
Abstract

Objective To analyze the dynamic changes and the influencing factors of T lymphocyte subsets in recipients with stable graft status within 1 year after lung transplantation. Methods Clinical data of 41 recipients with stable graft status after allogeneic lung transplantation were analyzed. The absolute value and ratio of T lymphocyte subsets in peripheral blood from recipients were measured by flow cytometry before operation, 2 weeks and each month (within 1 year) after operation, respectively. The effects of age, gender, body mass index (BMI), surgical method, incidence of primary graft dysfunction (PGD) after operation, and primary disease upon the absolute values of T lymphocytes were evaluated. Results Within 1 year after lung transplantation, the absolute values of CD3+, CD3+CD4+, CD3+CD8+T lymphocytes and CD4+/CD8+ ratio were changed over time (all P < 0.001). Compared with preoperative values, there was no statistical significance in the absolute values of CD3+ and CD3+CD4+T lymphocytes at 12 months after operation (P=0.659, 0.109), whereas the absolute value of CD3+CD8+T lymphocytes was increased (P=0.02) and the CD4+/CD8+ ratio was decreased (P < 0.001). Age, gender, BMI, surgical method and incidence of PGD after operation exerted no significant effect on the dynamic changes of absolute values of CD3+CD4+ and CD3+CD8+T lymphocytes (all P > 0.05). Primary disease before lung transplantation exerted no effect on the changes of CD3+CD4+T lymphocytes, whereas the postoperative absolute value of CD3+CD8+T lymphocytes was higher in recipients with infectious lung diseases (P < 0.05). Conclusions The absolute values of CD3+, CD3+CD4+, CD3+CD8+T lymphocytes in recipients with stable graft status after lung transplantation are relatively low in the early stage after lung transplantation, then gradually restore, and stabilize at 6 months after operation. Dynamic changes are not associated with age, gender, BMI, surgical method and incidence of PGD after operation of recipients.

Published
2021

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