Effect of Tension Temperature on the Anisotropy of Tensile Behavior for Az31 Alloys: A Visco-Plastic Self-Consistent Analysis

Wenke Wang,Jaimyun Jung,Chao Cui,Wenzhen Chen,Yang Yu,Peng Li,Wencong Zhang,Renlong Xiong,김형섭 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.4

In this work, the anisotropy variation of tensile flow stress for AZ31 magnesium alloys was investigated at various temperaturesand tensile strains with the help of the visco-plastic self-consistent model. The results showed that the anisotropyof flow stress was weakened with the increase of tensile temperature, while such anisotropy presented a slightly increasingstage first and then a continuously decreasing stage with the increase of tensile strain. During the tension deformation, theactivations of basal slip and tension twinning, together contributed to the development of a (0002)//LD (LD: loading direction)type texture. In contrast, the activations of prismatic slip produced a ⟨10–10⟩//LD type texture. Such texture variationsinfluenced the Taylor factors, but did not cause significant differences in the flow stress. By comparison, the difference inthe macroscopic average resolved shear stress, which was calculated according to the critical resolved shear stress of eachdeformation mode and their respective activation fractions, decreased significantly with the increase of tensile temperatureor tensile strain. This was the major reason for the decline of the tension deformation behavior anisotropy.

Analysis of Stress States in Compression Stage of High Pressure Torsion Using Slab Analysis Method and Finite Element Method

Wenke Wang,Yuepeng Song,Dongsheng Gao,Eun Yoo Yoon,이동준,이종수,김형섭 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.5

High pressure torsion (HPT) is useful for achieving substantial grain refinement to ultrafine grained/nanocrystalline states in bulk metallic solids. Most publications that analyzed the HPT process used experimental and numerical simulation approaches, whereas theoretical stress analyses for the HPT process are rare. Because of the key role of compression stage for the deformation of HPT, this paper aims to conduct a theoretical analysis and to establish a practical formula for stress and forming parameters of HPT process using the slab analysis method. Three equations were obtained via equations derivation to describe the normal stress states corresponding to the three zones of plastic deformation for HPT process as stick zone, drag zone and slip zone. As to the compression stage of HPT, the stress distribution results using the finite element method agree well with those using the slab analysis method. There are drag and stick zones on the contact surface of the HPT sample, as verified by the finite element method (FEM) and slab analysis method.

Finite Element Analysis of the Effect of Friction in High Pressure Torsion

Yuepeng Song,Wenke Wang,Dongsheng Gao,Eun Yoo Yoon,이동준,김형섭 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.3

High pressure torsion (HPT) is one of the most important techniques among various methods that createsevere plastic deformation in the production of bulk materials with nano/ultrafine grained microstructures. Since the driving force in deforming the workpiece in HPT is surface friction, understanding of the frictioneffect is critical for successful application of HPT. In this study, the friction effect in HPT was analyzed usingthe finite element method. The distribution of effective strain on the contact surface of the HPT samplesunder different friction conditions was investigated. The friction force influenced the effective strain morein the middle and edge regions than in the central region. The condition for the minimum friction factor thatcould achieve a sticking condition between the surfaces of the dies, and the samples in the middle and edgeregions, was investigated. There was a critical friction coefficient in which the effective strain varies sharplywith an increasing friction coefficient.

Thickness Inhomogeneity in Hardness and Microstructure of Copper After the Compressive Stage in High-Pressure Torsion

Yuepeng Song,Wenke Wang,이동준,정혁재,이성학,김형섭 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.1

Distinction between plastic deformation occuring in compression and compression–torsion stages isimportant for understanding the properties and microstructures of materials processed by high-pressure torsion(HPT). In the present study, remarkable through-thickness inhomogeneities of hardness and microstructurewere found in the samples processed by compression stage of HPT. Three regions on the radialdirection plane of compressed disks were defined to display the inhomogeneity: edge zone (high hardness),radial medium zone (uniform hardness) and center zone (low hardness near the surface and highhardness in the thickness central plane). A low hardness region in the center near the surface was detectedand found to stretch along the upper and bottom surfaces of the disks compressed by low pressure. Thislow hardness region was also found to decrease with increasing the pressure. Not only the hardness butalso the microstructure through-thickness inhomogeneity is attributed to stress and strain distribution in thedisk as well as to a huge friction between the anvil and the disk during processing.

Hardness and microstructure of interstitial free steels in the early stage of high-pressure torsion

Song, Yuepeng,Wang, Wenke,Gao, Dongsheng,Yoon, Eun Yoo,Lee, Dong Jun,Lee, Chong Soo,Kim, Hyoung Seop Springer-Verlag 2013 JOURNAL OF MATERIALS SCIENCE - Vol.48 No.13

Inhomogeneous Deformation of Interstitial Free Steel during the High Pressure Torsion Process

Yuepeng Song,Miaomiao Chen,Wenke Wang,Baoyan Xu,Dongsheng Gao,Shuai Zhang,Hyoung Seop Kim 대한금속ㆍ재료학회 2017 대한금속·재료학회지 Vol.55 No.10

Interstitial free (IF) steel disks were subjected to various degrees of revolution during application of the high-pressure torsion (HPT) process, and the resulting distributions of hardness and microstructure during the early torsion stage of high-pressure torsion (HPT) were investigated using experimental and simulation approaches. The results indicated that the deformation in the HPT-processed IF steel disk was inhomogeneous, producing low hardness in the center and high hardness in the edge region. The experimental results, including the hardness and microstructure distributions, indicated that the severe deformation zone proceeds gradually from the center to the edge of the HPT disks in the early torsion stage, and also confirmed verify that the deformation on the upper surface of the disks lags behind that on the bottom surface. Simulation results from a finite element method analysis strongly supported the experimental conclusions. (Received December 30, 2016; Accepted July 2, 2017)

Effects of red/blue versus white LED light of different intensities on the growth and organic carbon and autotoxin secretion of hydroponic lettuce

Chengbo Zhou,Qi Wang,Wenke Liu,Baoshi Li,Mingjie Shao,Yubin Zhang 한국원예학회 2022 Horticulture, Environment, and Biotechnology Vol.63 No.2

Light is a crucial signal for plant growth, development, and secondary metabolism. Exploring the effects of light on autotoxin secretion in lettuce can be helpful for improving the utilization efficiency of the nutrient solution in plant factories. The effects of white light (WL) and the combination of red (R) and blue (B) light (RB, 4R:1B) at different intensities (150, 200, and 250 μmol m −2 s −1) on the growth and root exudates of hydroponic lettuce (Lactuca sativa L.) were studied in a closed plant factory. The lettuce biomass and photosynthetic rate increased with the increasing light intensity, and the photosynthetic rate was significantly lower under WL than under RB at both 200 and 250 μmol m −2 s −1 . Lettuce under WL had the longest root length and highest root surface area at 200 μmol m −2 s −1 , while the root length, root surface area, and root volume under RB were the highest at 250 μmol m −2 s −1 . Total organic carbon (TOC) content of root exudates in the nutrient solution based on shoot or root dry weight decreased with the increasing light intensity. With the increase in light intensity, the secretion of four autotoxins (benzoic acid, ferulic acid, gallic acid, and tannic acid) based on shoot dry weight and root dry weight decreased under WL. Compared with RB, WL significantly reduced the secretion of autotoxins at 250 μmol m −2 s −1 . In conclusion, 250 μmol m −2 s −1 white light should be used for high lettuce yield, and it could also decrease the autotoxins in the nutrient solution and the occurrence of autotoxicity.

Evidence for the medicinal value of Squama Manitis (pangolin scale): A systematic review

Xinyao Jin,Hui Zi Chua,Keyi Wang,Nan Li,Wenke Zheng,Wentai Pang,Fengwen Yang,Bo Pang,Mingyan Zhang,Junhua Zhang 한국한의학연구원 2021 Integrative Medicine Research Vol.10 No.1

Background: Squama Manitis (pangolin scale) has been used in traditional Chinese medicine for thousands of years. However, its efficacy has not been systematically reviewed. This review aims to fill the gap. Methods: We searched six electronic databases including PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure Database (CNKI), WanFang Database and SinoMed from inception to May 1, 2020. Search terms included “pangolin”, “Squama Manitis”, “Manis crassicaudata”, “Manis javanica”, “Malayan pangolins”, “Manis pentadactyla”, “Ling Li”, “Chuan Shan Jia”, “Shan Jia”, “Pao Jia Zhu”, “Jia Pian” and “Pao Shan Jia”. The Cochrane Risk of Bias (RoB) assessment tool and Newcastle-Ottawa Scale (NOS) were used to evaluate the risk of bias of the included randomized controlled trials (RCTs) and case control studies (CCSs). Results: After screening, 15 articles that met the inclusion criteria were finally included. There were 4 randomized controlled trials, 1 case control study, 3 case series and 7 case reports. A total of 15 different diseases were reported in these studies, thus the data could not be merged to generate powerful results. Two RCTs suggested that Squama Manitis combined with herbal decoction or antibiotics could bring additional benifit for treating postpartum hypogalactia and mesenteric lymphadenitis. However, this result was not reliable due to low methodological quality and irrational outcomes. The other two RCTs generated negative results. All the non-RCTs did not add any valuable evidence to the efficacy of Squama Manitis beacause of small samples, incomplete records, non-standardized outcome detection. In general, currently available evidence cannot support the clinical use of Squama Manitis. Conclusion: There is no reliable evidence that Squama Manitis has special medicinal value. The removal of Squama Manitis from Pharmacopoeia is rational.

Association between the severity of hypodontia and the characteristics of craniofacial morphology in a Chinese population: A cross-sectional study

Xin Xiong,Jiaqi Liu,Yange Wu,Chengxinyue Ye,Qinlanhui Zhang,Yufan Zhu,Wenke Yang,Jun Wang 대한치과교정학회 2023 대한치과교정학회지 Vol.53 No.3

Objective: To investigate craniofacial differences in individuals with hypodontia and explore the relationship between craniofacial features and the number of congenitally missing teeth. Methods: A cross-sectional study was conducted among 261 Chinese patients (males, 124; females, 137; age, 7–24 years), divided into four groups (without hypodontia: no teeth missing, mild: one or two missing teeth, moderate: three to five missing teeth, severe: six or more missing teeth) according to the number of congenitally missing teeth. Differences in cephalometric measurements among the groups were analyzed. Further, multivariate linear regression and smooth curve fitting were performed to evaluate the relationship between the number of congenitally missing teeth and the cephalometric measurements. Results: In patients with hypodontia, SNA, NA-AP, FH-NA, ANB, Wits, ANS-Me/N-Me, GoGn-SN, UL-EP, and LL-EP significantly decreased, while Pog-NB, AB-NP, N-ANS, and S-Go/N-Me significantly increased. In multivariate linear regression analysis, SNB, Pog-NB, and S-Go/N-Me were positively related to the number of congenitally missing teeth. In contrast, NA-AP, FH-NA, ANB, Wits, N-Me, ANS-Me, ANS-Me/N-Me, GoGn-SN, SGn-FH (Y-axis), UL-EP, and LL-EP were negatively related, with absolute values of regression coefficients ranging from 0.147 to 0.357. Further, NA-AP, Pog-NB, S-Go/N-Me, and GoGn-SN showed the same tendency in both sexes, whereas UL-EP and LL-EP were different. Conclusions: Compared with controls, patients with hypodontia tend toward a Class III skeletal relationship, reduced lower anterior face height, flatter mandibular plane, and more retrusive lips. The number of congenitally missing teeth had a greater effect on certain characteristics of craniofacial morphology in males than in females.

Tongue features of patients with coronavirus disease 2019: a retrospective cross-sectional study

Wentai Pang,Dong Zhang,Junhua Zhang,Nan Li,Wenke Zheng,Hui Wang,ChunxiangLiu,Fengwen Yang,Pang Bo 한국한의학연구원 2020 Integrative Medicine Research Vol.9 No.3

Background: Traditional Chinese medicine (TCM) has been widely used in the treatment of coronavirus disease 2019 (COVID-19). Tongue features should be referred for diagnosis and treatment of diseases in TCM. Therefore, it is necessary to analyze the tongue features of the patients suffered from COVID-19. Methods: COVID-19 Symptom Database (established by Evidence-based Medicine Center of Tianjin University of TCM) was searched for eligible tongue pictures. The tongue pictures were assessed by TCM experts to extract the data of tongue color, coating color, tongue body shape and coating proper feature. The relationship between tongue features and patient’s condition was analyzed. Results: Patients diagnosed as mild and moderate COVID-19 commonly had light red tongue and white coating. Severe patients had purple tongue and yellow coating. The proportion of critical patients with tender tongue increased to 75%. Greasy coating was a significant characteristic of patients with COVID-19. The proportions of greasy coating were 53.3%, 73.3%, 83.6% and 87.5% in disease category of mild, moderate, severe and critical. In addition, the thick coating proportion increased from mild (24.9%) to critical (50.0%). Conclusions: Tongue features have certain relationship with the category of COVID-19. Tongue features can serve as potential indicators for the evaluation of patient’s condition and prognosis. Further studies are needed to enhance the quantification of tongue features and develop standards.