Effects of environmental temperature and age on the elastic modulus of concrete

Shuzhen Yang,Baodong Liu,Yuzhong Li,Minqiang Zhang 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.6

Concrete mechanical properties change constantly with age, temperature, humidity and the other environmental factors. This research studies the effects of temperature and age on the development of concrete elastic modulus by a series of prism specimens. Elastic modulus test was conducted at various temperatures and ages in the laboratory to examine the effects of temperature and age on it. The experimental results reveal that the concrete elastic modulus decreases with the rise of temperature but increases with age. Then, a temperature coefficient K is proposed to describe the effects of temperature and validated by existing studies. Finally, on the basis of K, analytical models are proposed to determine the elastic modulus of concrete at a given temperature and age. The proposed models can offer designers an approach to obtain more accurate properties of concrete structures through the elastic modulus modification based on actual age and temperature, rather than using a value merely based on laboratory testing.

Long-term development of compressive strength and elastic modulus of concrete

Shuzhen Yang,Baodong Liu,Mingzhe Yang,Yuzhong Li 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.2

Compressive strength and elastic modulus of concrete are constantly changing with age. In order to determine long-term development of compressive strength and elastic modulus of concrete, an investigation of C30 concrete cured in air conditions was carried out. Changes of compressive strength and elastic modulus up to 975 days were given. The results indicated that compressive strength and elastic modulus of concrete rapidly increased with age during the initial 150 days and then increased slowly. The gain in elastic modulus was slower than that of compressive strength. Then relationships of time-compressive strength, time-elastic modulus and compressive strength-elastic modulus were proposed by regression analysis and compared with other investigations. The trends of time-compressive strength and time-elastic modulus with age agreed best with ACI 209R-92. Finally, factors contributed to long-term development of compressive strength and elastic modulus of concrete were proposed and briefly analyzed.

Long-term development of compressive strength and elastic modulus of concrete

Yang, Shuzhen,Liu, Baodong,Yang, Mingzhe,Li, Yuzhong Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.2

Compressive strength and elastic modulus of concrete are constantly changing with age. In order to determine long-term development of compressive strength and elastic modulus of concrete, an investigation of C30 concrete cured in air conditions was carried out. Changes of compressive strength and elastic modulus up to 975 days were given. The results indicated that compressive strength and elastic modulus of concrete rapidly increased with age during the initial 150 days and then increased slowly. The gain in elastic modulus was slower than that of compressive strength. Then relationships of time-compressive strength, time-elastic modulus and compressive strength-elastic modulus were proposed by regression analysis and compared with other investigations. The trends of time-compressive strength and time-elastic modulus with age agreed best with ACI 209R-92. Finally, factors contributed to long-term development of compressive strength and elastic modulus of concrete were proposed and briefly analyzed.

Optimization of Medium Components for Plasmid Production by Recombinant E. coli $DH5{\alpha}$ $pUK21CMV{\beta}1.2$

Zheng, Shuzhen,Friehs, Karl,He, Ning,Deng, Xu,Li, Qingbiao,He, Zheng,Xu, Chenyun,Lu, Yinghua Korean Society for Biotechnology and Bioengineerin 2007 Biotechnology and Bioprocess Engineering Vol.12 No.3

In this study we investigated the effects of carbon and nitrogen sources, and the carbon to nitrogen ratio (C:N) of growth medium on the production of plasmid DNA by $pUK21CMV{\beta}1.2$ harbouring recombinant E. coli. The results indicated that sucrose and casein peptone were the most suitable carbon and nitrogen sources, respectively, for plasmid production, and the plasmid concentration was significantly influenced by the C:N ratio. A Box-Behnken design and surface response methodology were employed to formulate the optimal medium. In the optimized medium, a plasmid concentration of 51.80mg/L and a plasmid selectivity of 23.49mg/g were achieved after 24h of incubation. These values were approximately 3.5 and 1.7 times higher, respectively, than those obtained on the original LB medium.

Optimization of Medium Components for Plasmid Production by Recombinant E. coli DH5α pUK21CMVβ1.2

Yinghua Lu,Shuzhen Zheng,Karl Friehs,Ning He,Xu Deng,Qingbiao Li,Zheng He,Chenyun Xu 한국생물공학회 2007 Biotechnology and Bioprocess Engineering Vol.12 No.3

In this study we investigated the effects of carbon and nitrogen sources, and the carbon to nitrogen ratio (C:N) of growth medium on the production of plasmid DNA by pUK21CMVβ1.2 harbouring recombinant E. coli. The results indicated that sucrose and casein peptone were the most suitable carbon and nitrogen sources, respectively, for plasmid production, and the plasmid concentration was significantly influenced by the C:N ratio. A Box-Behnken design and surface response methodology were employed to formulate the optimal medium. In the optimized medium, a plasmid concentration of 51.80 mg/L and a plasmid selectivity of 23.49 mg/g were achieved after 24 h of incubation. These values were approximately 3.5 and 1.7 times higher, respectively, than those obtained on the original LB medium.

Investment and Risk Control of China's Mining Enterprises

Yunzhong Liu,Li Gao,Shuzhen Yao,Lin Yang 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10

Mining investment environment influences mining business risk factors. How enterprises face changing environment and implement successful risk management is the central task for mining enterprise management and development. This paper begins with the analysis of Chinn"s mining invesment environment, identifiesrisk factors of S Mining Limited Company, explores its risk control countermeasures, and propose resolutions of risk management for mining enterprises.

Complete chloroplast genome sequence and phylogenetic analysis of Rhododendron molle G. Don, an endangered Ericaceae species located on Dabie Mountains (central China)

Xu Bilin,Li Zhiliang,Liu Yan,Zhang Wanjing,Yu Jiaojun,Dong Hongjin,Zhang Jialiang,Wang Shuzhen 한국식물생명공학회 2023 Plant biotechnology reports Vol.17 No.2

Rhododendron molle G. Don, an endemic species of the Ericaceae family, possesses valuable medicinal and horticultural values. In this research, R. molle cp genome proved to be a typical quadripartite structure with the length of 200,878 bp. In particular, the lengths of large single-copy region (LSC), small single-copy region (SSC), and inverted repeat regions (IR) were 198,019 bp, 629 bp, and 1117 bp, respectively. Among the 149 unique genes, 97 were protein-coding genes, 44 were tRNA genes, and 8 were rRNA genes, respectively. Leucine was the most representative amino acid (10.663%), while Cysteine was the lowest representative (1.178%). A set of 30 codons showed obvious codon usage bias, while 29 were A/U-ending codons. Six gene regions showed high levels of nucleotide diversity (Pi > 0.02). Totally, 273 SSRs were identified. Maximum-likelihood (ML) phylogenetic analysis revealed that R. molle was relatively closed to the R. pulchrum and R. delavayi. High similarity was detected among Ericaceae species, and the coding regions were more conserved than the non-coding regions. Expansion and contraction detected in IR region could be the main length variation in R. molle and related Ericaceae species. This research will supply rich genetic resource for R. molle and related species of Ericaceae.

Simultaneous removal of sulphide and nickel by the compound of Chitosan Schiff Base from crude oil under microwave irradiation

Lei Wang,Quanming Peng,Shuzhen Li,Liucheng Du,Haijun Cai 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2

A study has been carried out for simultaneous desulfurization and demetalization by electric desalting from crude oil based on the oxidation of alkyl thiophene and nickel compounds with the compound of Chitosan Schiff Base under the condition of microwave irradiation (SDDM). Besides, an investigation has been made about the influence of Chitosan Schiff Base compound dose, initial temperature, and microwave time on desulfurization and demetalization. By using the optimized conditions for SDDM, up to 56% of sulfur and 82% of nickel removal rates were achieved for model compounds in crude oil samples. With the same conditions but without microwave the removal efficiency was lower than 56%for sulfur model compound and than 82% for nickel porphyrin in crude oil samples. Additionally, in order to develop a fundamental understanding of the SDDM mechanism of sulfides, a molecular simulation of sulfur compounds was performed with both the Hartree–Fock (HF) and second-order Moller–Plesset (MP2) levels of theory for the calculation of reaction kinetic rate by using Gaussian 03 program package. In comparison with conventional desulfurization and demetalization technology, the proposed SDDM process can accomplish the simultaneous removal of sulfur and nickel compounds from crude oil under relatively mild conditions.

Transformations of phenol into fuel over TiO2–CeO2/ZSM-5 aided by ultrasound and ultraviolet

Lei Wang,Fang yuan,Luoxin Liu,Nchare Mominou,Shuzhen Li,Cheng Li,Wenjiu Wang 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1

A novel technology, named transformations of phenol into fuel over TiO2–CeO2/ZSM-5 aided byultrasound and ultraviolet (TPFU), was developed. ZSM-5 zeolite was adjusted by TiO2 and CeO2 bymeans of impregnation. X-ray diffraction (XRD) and scanning electron microscope (SEM) analysisindicated the ZSM-5 remained intact after modification, and the titanium and cerium partly entered thecatalyst channel. The effect of temperature, pressure, space speed, and phenol to the catalyst ratio on theproduction yield was studied. The model compounds were transformed into fuel on the conditions oftemperature 300 8C; pressure 0.11 MPa, space velocity 1.0 h 1, and the ratio 1.5. Gasoline and diesel oilyield, and phenol compound conversion rate reached the maximum values of 50.1%, 44.1% and 98.5%,respectively. Meanwhile, biomass oil was transformed into fuel under the best conditions. The content ofaromatic compounds and alkane compounds in refined oil was higher than that in biomass crude oil, andphenol content has a significant decrease.