An improved Corten-Dolan’s model based on damage and stress state effects

Huiying Gao,Hong-Zhong Huang,Zhiqiang Lv,Fang-Jun Zuo,Hai-Kun Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8

The value of exponent d in Corten-Dolan’s model is generally considered to be a constant. Nonetheless, the results predicted on thebasis of this statement deviate significantly from the real values. In consideration of the effects of damage and stress state on fatigue lifeprediction, Corten-Dolan’s model is improved by redefining the exponent d used in the traditional model. The improved model performsbetter than the traditional one with respect to the demonstration of a fatigue failure mechanism. Predictions of fatigue life on thebasis of investigations into three metallic specimens indicate that the errors caused by the improved model are significantly smaller thanthose induced by the traditional model. Meanwhile, predictions derived according to the improved model fall into a narrower dispersionzone than those made as per Miner’s rule and the traditional model. This finding suggests that the proposed model improves the life predictionaccuracy of the other two models. The predictions obtained using the improved Corten-Dolan’s model differ slightly from thosederived according to a model proposed in previous literature; a few life predictions obtained on the basis of the former are more accuratethan those derived according to the latter. Therefore, the improved model proposed in this paper is proven to be rational and reliable giventhe proven validity of the existing model. Therefore, the improved model can be feasibly and credibly applied to damage accumulationand fatigue life prediction to some extent.

RNAi-Mediated Gene Silencing of Trcot1 Induces a Hyperbranching Phenotype in Trichoderma reesei

Fei Gao,Mengzhu Li,Weiquan Liu,Yingguo Bai,Tu Tao,Yuan Wang,Jie Zhang,Huiying Luo,Bin Yao,Huoqing Huang,Xiaoyun Su 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.2

Trichoderma reesei is the major filamentous fungus used to produce cellulase and there is huge interest in promoting its ability to produce higher titers of cellulase. Among the many factors affecting cellulase production in T. reesei, the mycelial phenotype is important but seldom studied. Herein, a close homolog of the Neurospora crassa COT1 kinase was discovered in T. reesei and designated TrCOT1, which is of 83.3% amino acid sequence identity. Functional disruption of Trcot1 in T. reesei by RNAi-mediated gene silencing resulted in retarded sporulation on potato dextrose agar and dwarfed colonies on minimal medium agar plates containing glucose, xylan, lactose, xylose, or glycerol as the sole carbon source. The representative mutant strain, SUS2/Trcot1i, also displayed reduced mycelia accumulation but hyperbranching in the MM glucose liquid medium, with hyphal growth unit length values decreased to 73.0 μm/tip compared to 239.8 μm/tip for the parent strain SUS2. The hyperbranching phenotype led to slightly but significantly increased cellulase secretion from 24 to 72 h in a batch culture. However, the cellulase production per unit of mycelial biomass was much more profoundly improved from 24 to 96 h.

Highly Porous Cellulose Microbeads and their Adsorption for Methylene Blue

Jiarui Hua,Ranju Meng,Tiejun Wang,Huiying Gao,Zhenze Luo,Yuanyuan Jin,Lin Liu,Juming Yao 한국섬유공학회 2019 Fibers and polymers Vol.20 No.4

Highly porous cellulose microbeads with porosity of more than 90 % were successfully prepared via a faciledissolution and subsequent regeneration of cellulose in H2SO4/Na2SO4 coagulation bath. Effects of coagulation temperature,H2SO4, and Na2SO4 concentration on the microstructure, average diameter, porosity, specific surface area, and mechanicalproperty of formed cellulose beads were investigated systematically. In view of the high porosity and specific area, thecellulose beads were used as adsorbents for dye removal. The results revealed that the porous cellulose beads exhibited highadsorption performance with maximum adsorption capacity of 48.80 mg/g for cationic dye methylene blue. Besides, theporous cellulose beads also presented a potential in practical application and its adsorption capacity for methylene blue stillretained 29.43 mg/g after six adsorption-desorption cycles.

Lifetime prediction for turbine discs based on a modified Walker strain model

Zhiqiang Lv,Hong-Zhong Huang,Huiying Gao,Fang-Jun Zuo,Hai-Kun Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

We created three-dimensional models of turbine disc and blades of a type of aero-engine according to their geometries. Extant studies show that low cycle fatigue is the main failure mechanism of turbine disc. By using a non-linear elastic-plasticfinite element method, the static stress and strain state of the critically high stress regions, which can lead to operational failures,are determined. On the basis of stress-strain relation, a modified Walker strain life prediction model is proposed with norequired knowledge on the mean stress correction. Then the predicted life data from the modified Walker strain model arecompared with the testing results. After the verification, the modified Walker strain life prediction model and Miner’s rule wereapplied to predict the lifetime of the turbine disc under various operating conditions.

The Risk Factors and Outcomes for Radiological Abnormalities in Early Convalescence of COVID-19 Patients Caused by the SARS-CoV-2 Omicron Variant: A Retrospective, Multicenter Follow-up Study

Wang Hong,Yang Qingyuan,Li Fangfei,Wang Huiying,Yu Jing,Ge Xihong,Gao Guangfeng,Xia Shuang,Xing Zhiheng,Shen Wen 대한의학회 2023 Journal of Korean medical science Vol.38 No.8

Background: The emergence of the severe acute respiratory syndrome coronavirus 2 omicron variant has been triggering the new wave of coronavirus disease 2019 (COVID-19) globally. However, the risk factors and outcomes for radiological abnormalities in the early convalescent stage (1 month after diagnosis) of omicron infected patients are still unknown. Methods: Patients were retrospectively enrolled if they were admitted to the hospital due to COVID-19. The chest computed tomography (CT) images and clinical data obtained at baseline (at the time of the first CT image that showed abnormalities after diagnosis) and 1 month after diagnosis were longitudinally analyzed. Uni-/multi-variable logistic regression tests were performed to explore independent risk factors for radiological abnormalities at baseline and residual pulmonary abnormalities after 1 month. Results: We assessed 316 COVID-19 patients, including 47% with radiological abnormalities at baseline and 23% with residual pulmonary abnormalities at 1-month follow-up. In a multivariate regression analysis, age ≥ 50 years, body mass index ≥ 23.87, days after vaccination ≥ 81 days, lymphocyte count ≤ 1.21 × 10-9/L, interleukin-6 (IL-6) ≥ 10.05 pg/mL and IgG ≤ 14.140 S/CO were independent risk factors for CT abnormalities at baseline. The age ≥ 47 years, presence of interlobular septal thickening and IL-6 ≥ 5.85 pg/mL were the independent risk factors for residual pulmonary abnormalities at 1-month follow-up. For residual abnormalities group, the patients with less consolidations and more parenchymal bands at baseline could progress on CT score after 1 month. There were no significant changes in the number of involved lung lobes and total CT score during the early convalescent stage. Conclusion: The higher IL-6 level was a common independent risk factor for CT abnormalities at baseline and residual pulmonary abnormalities at 1-month follow-up. There were no obvious radiographic changes during the early convalescent stage in patients with residual pulmonary abnormalities.

Determining the Walker exponent and developing a modified Smith-Watson-Topper parameter model

Zhiqiang Lv,Hong-Zhong Huang,Hai-Kun Wang,Huiying Gao,Fang-Jun Zuo 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.3

Mean stress effects significantly influence the fatigue life of components. In general, tensile mean stresses are known to reduce the fatigue life of components, whereas compressive mean stresses are known to increase it. To date, various methods that account for mean stress effects have been studied. In this research, considering the high accuracy of mean stress correction and the difficulty in obtaining the material parameter of the Walker method, a practical method is proposed to describe the material parameter of this method. The test data of various materials are then used to verify the proposed practical method. Furthermore, by applying the Walker material parameter and the Smith-Watson-Topper (SWT) parameter, a modified strain-life model is developed to consider sensitivity to mean stress of materials. In addition, three sets of experimental fatigue data from super alloy GH4133, aluminum alloy 7075-T651, and carbon steel are used to estimate the accuracy of the proposed model. A comparison is also made between the SWT parameter method and the proposed strainlife model. The proposed strain-life model provides more accurate life prediction results than the SWT parameter method.