The investigation of pH threshold value on the corrosion of steel reinforcement in concrete

Qi Pu,Yan Yao,Ling Wang,Xingxiang Shi,Jingjing Luo,Yifei Xie 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.3

The aim of this study is to investigate the pH threshold value for the corrosion of steel reinforcement in concrete. A method was designed to attain the pH value of the pore solution on the location of the steel in concrete. Then the pH values of the pore solution on the location of steel in concrete were changed by exposing the samples to the environment (CO25%, RH 40%) to accelerate carbonation with different periods. Based on this, the pH threshold value for the corrosion of steel reinforcement had been examined by the methods of half-cell potential and electrochemical impedance spectra (EIS). The results have indicated that the pH threshold value for the initial corrosion of steel reinforcement in concrete was 11.21. However, in the carbonated concrete, agreement among whether steel corrosion was initiatory determined by the detection methods mentioned above could be found.

Explicit co-simulation with interface Jacobian approximation

Pu Li,Qi Yuan 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.3

Explicit co-simulation denotes a weak coupling of subsystems without iteration between the communication time points (macro-time points). Extrapolated polynomials are commonly used to represent coupling variables. The error introduced by the polynomials can induce instability. Partial derivatives of the interface variables are used in the iterative cosimulation (implicit or semi-implicit co-simulation) to enhance stability. However, repetition of macro-time step becomes a main drawback especially for practical applications. In this manuscript we approximate the interface Jacobian using a truncated matrix exponential and study the numerical behavior in the framework of explicit co-simulations. The stability is greatly improved compared to the classical explicit method. The error of the interface Jacobian approximation has been investigated. A supported pendulum is used to validate the proposed cosimulation method.

Synthesis, Crystal Structure and Property Studies on a Tetrachlorocuprate Salt of an Organic Cation

Pu Su Zhao,Fang Fang Jian,Yong Qi Qin,Jing Zhang 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.7

Influence of coupling approximation on the numerical stability of explicit co-simulation

Pu Li,Qi Yuan 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6

Co-simulation allows the parallelization of several subsystems in a distributed manner with data exchanges at discrete user-defined communication points (macro-time points). Between two macro-time points, subsystems are integrated in a local circumstance using specified solvers. By adopting the technique, the computational efficiency can be enhanced greatly without exposure of inner information. As a weak coupling, communication between subsystems is usually approximated by extrapolated or interpolated polynomials that may induce instability. Implicit or semi-implicit co-simulation with iteration of macro-time steps can improve stability behavior significantly. However, reinitialization may be unfeasible for realtime simulation or not supported by most commercial tools. Therefore, stabilized non-iterative co-simulation has been more popular that can be achieved either by appropriate communication techniques or by interface error estimations. However, the influence of the coupling approximations on numerical stability is not well understood. In this paper, the numerical stability of explicit co-simulation will be studied using different approximations of coupling techniques. The influence of communication schemes (parallel and sequential coupling scheme), least square as well as relaxation techniques using an applied force coupling approach will be investigated quantitatively with the help of a linear two-mass oscillator. A quarter car model is used to validate the stability analysis of the linear oscillator. The results indicate that by adopting appropriate coupling techniques, stability improvement can be accomplished. Higher order of extrapolation (interpolation) introduces damping to the distributed system while relaxation and least square approaches might trigger artificial oscillations.

Changes in Dust Activity in Spring over East Asia under a Global Warming Scenario

Qi Zong,Rui Mao,Dao-Yi Gong,Chenglai Wu,Bing Pu,Xingya Feng,Yijie Sun 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.4

Dust activity not only influences human health through dust storms but also affects climate at local and regional scales through the direct effects of dust aerosols on both solar and longwave radiative heating. In this study, based on dust simulations from seven Coupled Model Intercomparison Project Phase 5 (CMIP5) models, the spatial and temporal changes in dust activity over East Asia under a Representative Concentration Pathway 8.5 global warming scenario were examined for the periods of 2016– 2035 (P1), 2046–2065 (P2) and 2080–2099 (P3). The results show that the multimodel ensemble mean (MME) of the CMIP5 models largely captures the spatial distribution of dust emissions and dust optical depth (DOD) over East Asia during 1986–2005 (P0). The MME reproduces the increasing trend in dust emissions and DOD over dust sources in East Asia during P0. Accompanying emission reductions during P1 to P3, the DOD simultaneously decreases, and the evident DOD decline can also be found over downwind areas in eastern China and the Korean Peninsula. Simulations project increases in precipitation and the LAI (leaf area index). Simultaneously, the weakened East Asian trough leads to anomalous southerly winds and lower wind speeds at the surface. All these results indicate unfavorable conditions for dust emissions over the sources regions, resulting in a decreased DOD over East Asia during P1 to P3.

Transformational Leadership, Psychological Capital and Front-line Sales Staffs’ Service Quality : Psychological Capital as a Mediator

Qi-chao He,Qiao An,Pu-xin Lin 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.7

Confronting diverse working pressure during office time, front-line sales staffs’ service quality will be threatened, which can affect customers’ satisfaction and loyalty degree, then influence market share and competitive edge of the company further. Thus, this paper focuses on the front-line sales staffs and aims at identifying the influence mechanism of transformational leadership on their service quality and the role of psychological capital among the triadic relationship. The result of hierarchy regression analysis about 250 sample data showed that both transformational leadership and psychological capital had significantly positive effect on front-line sales staffs’ service quality, while psychological capital acted as mediator between transformational leadership and front-line sales staffs’ service quality. Organizational management is advised to adopt transformational leadership and promote the employees’ level of psychological capital so as to improve the service quality of front-line sales staffs and the entire company.

Effects of Fdft 1 gene silencing and VD3 intervention on lung injury in hypoxia-stressed rats

Pu Xiaoyan,Lin Xue,Qi Yinglian,Li Yinglian,Li Tiantian,Liu Yang,Wei Dengbang 한국유전학회 2022 Genes & Genomics Vol.44 No.10

Background: Hypoxia can induce lung injury such as pulmonary arterial hypertension and pulmonary edema. And in the rat model of hypoxia-induced lung injury, the expression of Farnesyl diphosphate farnesyl transferase 1 (Fdft 1) was highly expressed and the steroid biosynthesis pathway was activated. However, the role of Fdft 1 and steroid biosynthesis pathway in hypoxia-induced lung injury remains unclear. Objective: The study aimed to further investigate the relationship between Fdft1 and steroid biosynthesis pathway with hypoxia-induced lung injury. Methods: A rat model of lung injury was constructed by hypobaric chamber with hypoxic stress, the adenovirus interference vector was used to silence the expression of Fdft 1, and the exogenous steroid biosynthesis metabolite Vitamin D3 (VD3) was used to treat acute hypoxia-induced lung injury in rats. Results: Sh-Fdft 1 and exogenous VD3 significantly inhibited the expression of Fdft 1 and the activation of the steroid pathway in hypoxia-induced lung injury rats, which showed a synergistic effect on the steroid activation pathway. In addition, sh-Fdft 1 promoted the increase of pulmonary artery pressure and lung water content, the decrease of oxygen partial pressure and oxygen saturation, and leaded to the increase of lung cell apoptosis and the aggravation of mitochondrial damage in hypoxia-stressed rats. And VD3 could significantly improve the lung injury induced by hypoxia and sh-Fdft 1 in rats. Conclusions: Fdft 1 gene silencing can promote hypoxic-induced lung injury, and exogenous supplement of VD3 has an antagonistic effect on lung injury induced by Fdft 1 gene silencing and hypoxic in rats, suggesting that VD3 has a preventive and protective effect on the occurrence and development of hypoxia-induced lung injury.

Improvement of the vibration performance of rod-fastened rotor by multioptimization on the distribution of original bending and unbalance

Bingxi Zhao,Qi Yuan,Pu Li 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

Manufacturing errors of disks, namely, parallelism error and mass imbalance, cause complex bending and unbalance of rod-fastened rotor (RFR) after assembly, which act as original excitations and increase vibration. A method was introduced in this study to improve the vibration performance of an RFR. The method optimized the distribution of bending and unbalance and offered an improved assembly scheme. As a basic step, the quantitative relation of RFR bending and assembly angles of disks with parallelism errors was established. On this basis, dimensionless bending was proposed to evaluate the integral bending of an RFR. With respect to the unbalance of the RFR, the balance principle of rigid rotor was applied, that is, small equivalent reaction forces were considered better. The dynamic model of an RFR supported by elliptic bearings was established by using finite element method. Optimizations on the bending and unbalance were then performed individually, and related vibration responses of the RFR system were investigated. Results of single optimization on bending and unbalance proved the effectiveness in reducing the vibration responses of the RFR system. Moreover, results revealed that the bending and unbalance induced mainly the vibration of first order, which explained the difficulty to distinguish each other in actual balance of an RFR. Finally, the multioptimization on the bending and unbalance was performed, which greatly decreased the vibration responses of the RFR system. Optimizations on bending and unbalance in this study were independent with supporting conditions, which gave them a better application and provided a new way to improve the dynamic performance before assembly.

Efficient Enantioselective Synthesis of (R)-[3, 5-Bis (trifluoromethyl) phenyl] Ethanol by Leifsonia xyli CCTCC M 2010241 Using Isopropanol as Co-Substrate

( Ou Yang Qi ),( Pu Wang ),( Jin Huang ),( Jin Bo Cai ),( Jun Yao He ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.3

(R)-[3,5-Bis(trifluoromethyl)phenyl] ethanol is a key chiral intermediate for the synthesis of aprepitant. In this paper, an efficient synthetic process for (R)-[3,5- bis(trifluoromethyl)phenyl] ethanol was developed via the asymmetric reduction of 3,5-bis(trifluoromethyl) acetophenone, catalyzed by Leifsonia xyli CCTCC M 2010241 cells using isopropanol as the co-substrate for cofactor recycling. Firstly, the substrate and product solubility and cell membrane permeability of biocatalysts were evaluated with different co-substrate additions into the reaction system, in which isopropanol manifested as the best hydrogen donor of coupled NADH regeneration during the bioreduction of 3,5-bis(trifluoromethyl) acetophenone. Subsequently, the optimization of parameters for the bioreduction were undertaken to improve the effectiveness of the process. The determined efficient reaction system contained 200mM of 3,5-bis(trifluoromethyl) acetophenone, 20% (v/v) of isopropanol, and 300 g/l of wet cells. The bioreduction was executed at 30oC and 200 rpm for 30 h, and 91.8% of product yield with 99.9% of enantiometric excess (e.e.) was obtained. The established bioreduction reaction system could tolerate higher substrate concentrations of 3,5- bis(trifluoromethyl) acetophenone, and afforded a satisfactory yield and excellent product e.e. for the desired (R)-chiral alcohol, thus providing an alternative to the chemical synthesis of (R)-[3,5-bis(trifluoromethyl)phenyl] ethanol.

CADMIUM TELLURIDE NANOCRYSTALS: SYNTHESIS, GROWTH MODE AND EFFECT OF REACTION TEMPERATURE ON CRYSTAL STRUCTURES

XIAO-YING QI,KAN-YI PU,QU-LI FAN,DUO-FENG TANG,GUI-AN WEN,FREDDY Y. C. BOEY,LIAN-HUI WANG,WEI HUANG,HUA ZHANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2008 NANO Vol.3 No.2

A series of cadmium telluride (CdTe) nanocrystals were synthesized by a modified organometallic synthesis method at various reaction temperatures ranging from 130 to 250°C. In this method, octadecylamine (ODA) was introduced as an additional coordinating component to the mixture of trioctylphosphine oxide (TOPO) and trioctylphosphine (TOP). CdO was used as a precursor. The prepared CdTe nanocrystals were studied by the absorption and emission spectra as well as the powder X-ray diffraction (XRD) patterns. The result shows that besides the traditional continuous-growth mode observed frequently at relatively high reaction temperature, a discontinuous-growth mode was confirmed at the initial growth stage of CdTe nanocrystals, arising from the change of the absorption spectra of CdTe nanocrystals with the reaction time at relatively low reaction temperature. The structures of CdTe nanocrystals, e.g., the cubic zinc blende structure at 160°C and the hexagonalwurtzite structure at 250°C, were characterized by XRD.