Experimental Investigation on Tensile Strength of Jurassic Red-Bed Sandstone under the Conditions of Water Pressures and Wet-Dry Cycles

Zhenhua Zhang,Xiaochuan Chen,Huayan Yao,Xiang Huang,Luwang Chen 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.7

Jurassic Red-Bed sandstone is one of the main types of rock composing unstable slopes on both banks of the Three Gorges Reservoir (TGR) in China. It is vulnerable to tensile strength degradation when exposed to cyclic wet-dry conditions under reservoir operation. Therefore, the law behind this needs to be clarified in order to accurately evaluate the stability of a sandstone slope located in the drawdown area of the TGR. In this paper, Jurassic Red-Bed sandstone specimens from the Majiagou landslide in the TGR area were collected for experiments with cyclic wet-dry procedures. After each wet-dry cycle, efforts were made to implement splitting tests, measure clay mineral contents and ion contents in the soak solution, and observe changes in microstructures. The tensile strength is experimentally demonstrated to be a process of damage accumulation under the integrated actions of water pressure, calcite dissolution, and clay mineral hydration, among which hydration of illite contributes the most to the damage. The loss of the cement material and the cyclic expansion and shrinkage of clay minerals weaken the cementation between grains, leading to the tensile strength degradation.

Wake effects of an upstream bridge on aerodynamic characteristics of a downstream bridge

Zhenhua Chen,Zhenyun Lin,Haojun Tang,Yongle Li,Bin Wang 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.6

To study the wake influence of an upstream bridge on the wind-resistance performance of a downstream bridge, two adjacent long-span cable-stayed bridges are taken as examples. Based on wind tunnel tests, the static aerodynamic coefficients and the dynamic response of the downstream bridge are measured in the wake of the upstream one. Considering different horizontal and vertical distances, the flutter derivatives of the downstream bridge at different angles of attack are extracted by Computational Fluid Dynamics (CFD) simulations and discussed, and the change in critical flutter state is further studied. The results show that a train passing through the downstream bridge could significantly increase the lift coefficient of the bridge which has the same direction with the gravity of the train, leading to possible vertical deformation and vibration. In the wake of the upstream bridge, the change in lift coefficient of the downstream bridge is reduced, but the dynamic response seems to be strong. The effect of aerodynamic interference on flutter stability is related to the horizontal and vertical distances between the two adjacent bridges as well as the attack angle of incoming flow. At large angles of attack, the aerodynamic condition around the downstream girder which may drive the bridge to torsional flutter instability is weakened by the wake of the upstream bridge, and the critical flutter wind speed increases at this situation.

The Design of Linear Magnetic Negative Stiffness Element for Engineering Application using Rectangular Permanent Magnets

Zhenhua Zhou,Shuhan Chen,Xin Liu 한국자기학회 2020 Journal of Magnetics Vol.25 No.2

Negative stiffness element (NSE) has extensive uses in engineering applications, such as vibration isolation, energy harvesting, and mechanical metamaterial. However, to realize a linear negative stiffness characteristic is still a challenging task. In this paper, we present a compact magnetic negative stiffness element (MNSE) that composed of three rectangular permanent magnets and configured as repelling configuration in horizontal to realize linear negative stiffness characteristic. The effects of the MNSE configuration parameters on the negative stiffness characteristic are analyzed in detail. The results demonstrate that the magnitude of the negative stiffness characteristic can be adjusted by changing the height ratio and width ratio between the central and outer magnets. The height difference between the central and outer magnets can be used to tune the degree of nonlinearity of the negative stiffness characteristic and to get the uniformity stiffness characteristic in the equilibrium position. The procedure to realize the linear negative stiffness characteristic with the expected magnitude and displacement range is developed and confirmed. The proposed MNSE and the design procedure offer an engineering application foundation for the magnetic linear negative stiffness.

Effects of chromium picolinate on fat deposition, activity and genetic expression of lipid metabolism-related enzymes in 21 day old Ross broilers

Chen, Guangxin,Gao, Zhenhua,Chu, Wenhui,Cao, Zan,Li, Chunyi,Zhao, Haiping Asian Australasian Association of Animal Productio 2018 Animal Bioscience Vol.31 No.4

Objective: This experiment was conducted to investigate the effects of chromium picolinate (CrP) on fat deposition, genetic expression and enzymatic activity of lipid metabolism-related enzymes. Methods: Two hundred forty one-day-old Ross broilers were randomly divided into 5 groups with 4 replicates per group and 12 Ross broiler chicks per replicate. The normal control group was fed a basal diet, and the other groups fed the same basal diet supplemented with 0.1, 0.2, 0.4, and 0.8 mg/kg CrP respectively. The experiment lasted for 21 days. Results: Added CrP in the basal diet decreased the abdominal fat, had no effects on subcutaneous fat thickness and inter-muscular fat width; 0.2 mg/kg CrP significantly decreased the fatty acid synthase (FAS) enzymatic (p<0.05); acetyl-CoA carboxylase (ACC) enzymatic activity decreased in all CrP groups (p<0.05); hormone-sensitive lipase (HSL) enzymatic activity also decreased, but the change was not significant (p>0.05); 0.4 mg/kg CrP group significantly decreased the lipoprotein lipase (LPL) enzymatic activity. FAS mRNA expression increased in all experimental groups, and the LPL mRNA expression significantly increased in all experimental groups (p<0.05), but not 0.2 mg/kg CrP group. Conclusion: The results indicated that adding CrP in basal diet decreased the abdominal fat percentage, had no effects on subcutaneous fat thickness and inter-muscular fat width, decreased the enzymatic activity of FAS, ACC, LPL and HSL and increased the genetic expression levels of FAS and LPL.

First-principles study of Ti doping in FeF3$0.33H2O

Zhenhua Yang,Zhijuan Zhang,Yalong Yuan,Yunqing Huang,Xianyou Wang,Xiaoying Chen,Shuangying Wei 한국물리학회 2016 Current Applied Physics Vol.16 No.8

The effect of Ti doping on the geometrical and electronic structures of FeF3$0.33H2O are systematically investigated by using the first principles calculations. We focused on TixFe1-xF3$0.33H2O systems, in which x is equal to 0, 0.08, 0.17 and 0.25, respectively. Different kinds of Ti dopant sites are checked and the most stable structure can be obtained by comparison of total energy. The crystal volume of TixFe1- xF3$0.33H2O expands gradually with increasing Ti doping concentration. Calculated formation energies indicate TixFe1-xF3 is easiest to fabricate and the difficulty of Ti doping FeF3 with hexagonal-tungstenbronze( HTB) structure decreases with the increase of Ti doping concentration under the Fe-rich and Ti-rich growth conditions. Moreover, TixFe1-xF3$0.33H2O is thermodynamically stable, indicating that water molecule can preferentially occupy one-dimensional cavity in the TixFe1-xF3. The band gap of TixFe1-xF3$0.33H2O decreases with increasing Ti doping concentration and Ti0.25Fe0.75F3$0.33H2O exhibits character of half metal, indicating that the conductivity of FeF3$0.33H2O can be improved by Ti-doping. Besides, it can be confirmed that Ti-doping also can broaden the hexagonal cavity in the FeF3$0.33H2O by analyzing the crystal structure of FeF3$0.33H2O and TixFe1-xF3$0.33H2O. With excellent conductivity and larger hexagonal cavity, TixFe1-xF3$0.33H2O can afford open diffusion channels. Therefore, Li ions can remain unblocked, which is beneficial to fast charge and discharge.

Effect of Anhydride Grafting Agent on Trap Levels of Low-Density Polyethylene

Lijuan He,Zhenhua Yuan,Xiong Yang,Huiqing Niu,Chao Zhu,Dawei Li,Lei Zhao,Chuntian Chen 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.5

Trap distribution of the low-density polyethylene(LDPE) modified by anhydride grafting agent was studied and the effect of grafting agent on the trap levels was analyzed by the method of Photo-stimulated Discharge in this paper. Different concentrations and types of same concentration of LDPE modified by anhydride grafting agent were measured by using continuous UV scanning. The results showed that different concentrations and types of grafting agent had effect on trap levels distribution of LDPE. The trap depth would decrease with the anhydride grafting agent content increasing and increase with its damaged condition increasing when anhydride grafting agent was destroyed. Anhydride grafting agent are widely applied to the production and research of high pressure insulating polyethylene materials. The purpose of this paper is to elaborate the effect of anhydride grafting agent on the insulating properties of polyethylene material and explain the strongest binding capacity of anhydride grafting agent to space charge.

WRKY71 Acts Antagonistically Against Salt-Delayed Flowering in Arabidopsis thaliana

Yu, Yanchong,Wang, Long,Chen, Jiacai,Liu, Zhenhua,Park, Chung-Mo,Xiang, Fengning Oxford University Press 2018 Plant & cell physiology Vol.59 No.2

Structural performance of novel SCARC column under axial and eccentric loads

Chunheng Zhou,Zongping Chen,Junhua Li,Liping Cai,Zhenhua Huang 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.5

A novel spiral confined angle-steel reinforced concrete (SCARC) column was developed in this study. A total of 16 specimens were prepared and tested (eight of them were tested under axial loading, the other eight were tested under eccentric loading). The failure processes and load-displacement relationships of specimens under axial and eccentric loads were examined, respectively. The load-carrying capacity and ductility were evaluated by parametric analysis. A calculation approach was developed to predict the axial and eccentric load-carrying capacity of these novel columns. Results showed that the spiral reinforcement provided enough confinement in SCARC columns under axial and low eccentric loads, but was not effective in that under high eccentric loads. The axial load-carrying capacity and ductility of SCARC columns were improved significantly due to the satisfactory confinement from spirals. The outer reinforcement and other construction measures were necessary for SCARC columns to prevent premature spalling of the concrete cover. The proposed calculation approach provided a reliable prediction of the load-carrying capacity of SCARC columns.

Cloning and Characterization of the Ammonium Transporter Genes BaAMT1;1 and BaAMT1;3 from Chinese Kale

Shiwei Song,Riyuan Chen,Zhenhua He,Xinmin Huang,Lihua Zhong,Houcheng Liu,Guangwen Sun 한국원예학회 2017 Horticulture, Environment, and Biotechnology Vol.58 No.2

Chinese kale (Brassica alboglabra L.) is a popular vegetable rich in important nutrients. Fertilization withappropriate ammonium:nitrate ratios enhances biomass production and quality. AMT-type ammonium transporters havebeen shown to mediate ammonium uptake across the plasma membrane. However, very little is known about themolecular regulation of growth and development by ammonium in Chinese kale, including how ammonium regulatesthe expression of AMT1 genes. In this study, we identified and characterized two AMT1 genes from B. alboglabra,BaAMT1;1 and BaAMT1;3. The full-length open reading frames of BaAMT1;1 and BaAMT1;3 were 1512 bp and1515 bp, respectively. Transient expression of the fusion proteins pBE-EGFP-BaAMT1;1 and pBE-EGFP-BaAMT1;3 inonion epidermal cells indicated that these transporters are located on the plasma membrane. BaAMT1;1 and BaAMT1;3were functional in yeast and complemented a mutant defective in ammonium transport. BaAMT1;1 was expressed invegetative organs and at high levels in roots, while BaAMT1;3 expression was root specific. In addition, we observedopposite responses of BaAMT1;1 and BaAMT1;3 expression to nitrogen starvation and ammonium resupply in roots. These results provide new insights into the molecular mechanisms underlying ammonium absorption in Chinese kale.

Effect of Occupational Health and Safety Management System on Work-Related Accident Rate and Differences of Occupational Health and Safety Management System Awareness between Managers in South Korea's Construction Industry

Yoon, Seok J.,Lin, Hsing K.,Chen, Gang,Yi, Shinjea,Choi, Jeawook,Rui, Zhenhua Occupational Safety and Health Research Institute 2013 Safety and health at work Vol.4 No.4

Background: The study was conducted to investigate the current status of the occupational health and safety management system (OHSMS) in the construction industry and the effect of OHSMS on accident rates. Differences of awareness levels on safety issues among site general managers and occupational health and safety (OHS) managers are identified through surveys. Methods: The accident rates for the OHSMS-certified construction companies from 2006 to 2011, when the construction OHSMS became widely available, were analyzed to understand the effect of OHSMS on the work-related injury rates in the construction industry. The Korea Occupational Safety and Health Agency 18001 is the certification to these companies performing OHSMS in South Korea. The questionnaire was created to analyze the differences of OHSMS awareness between site general managers and OHS managers of construction companies. Results: The implementation of OHSMS among the top 100 construction companies in South Korea shows that the accident rate decreased by 67% and the fatal accident rate decreased by 10.3% during the period from 2006 to 2011. The survey in this study shows different OHSMS awareness levels between site general managers and OHS managers. The differences were motivation for developing OHSMS, external support needed for implementing OHSMS, problems and effectiveness of implementing OHSMS. Conclusion: Both work-related accident and fatal accident rates were found to be significantly reduced by implementing OHSMS in this study. The differences of OHSMS awareness between site general managers and OHS managers were identified through a survey. The effect of these differences on safety and other benefits warrants further research with proper data collection.