Mechanical and Engineering Behavior of MICP-Treated Coarse Siliceous Sands

Zhigang Shan,Peng Zhang,Hailei Kou 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.1

Microbial-induced calcium carbonate precipitation (MICP) technology has been widely used in geotechnical engineering. The undrained and unconsolidated (UU) triaxial tests were conducted in this study to investigate the effect of bio-cementation concentration and treatment times on the mechanical behavior of MICP treated siliceous sands. Test results indicated that the strength of treated specimen is significantly affected by the bio-cementation concentration. The normalized σ 'p/σ 'p_u increases exponentially with treatment times and produced calcium carbonate. For the same treatment times, the higher the bio-cementation concentration, the larger the produced calcium carbonate and smaller corresponding failure strain. The void ratio and permeability of treated specimens decrease lineally with treatment times increase. The higher the used bio-cementation concentration, the larger the reduction of void ratio and permeability. SEM analysis illustrates that when the bio-cementation concentration is 0.5 mol/L, the crystal form of calcium carbonate is mainly spherical, while the concentrations are 0.7 mol/L and 1.0 mol/L, the crystal form of calcium carbonate is mainly block. This can explain from the perspective that the treatment effect of 0.7 mol/L and 1.0 mol/L bio-cement cementation is better than that of 0.5 mol/L.

An Experimental Study on Behaviour of Reinforced Concrete T-shaped Columns Subjected to Combined Loads

Zhigang Yu,Deshan Shan 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.3

Reinforced concrete girders of curved cable-stayed bridges are subjected to the combined loads of compression-bending-shear-torsion, which can result in complex interaction behaviours. This paper presents an experimental study conducted to understand the behaviours of T-shaped reinforced concrete columns subjected to the combined loads of compression-bending-shear-torsion. The main variables considered in this study are axial pressure ratio and torsional change. The results of tests on twelve reinforced concrete columns subjected to the combined loads are obtained, and the effects of combined loads on the bending strength are discussed. This paper presents the formula established for calculating the bending strength and the diagrams of interaction under the combined loads of compression-bending-shear-torsion. Particularly, the results highlight the turning point from the bending failure to the compression failure, and demonstrate that bending capability increases within the specified range of axial pressure ratio and decreases with the increasing torsion. In addition, this study indicates the importance of considering the effects of compression, shear and torsion on bending strength in the engineering design.

Rapid Detection of Food-borne Listeria monocytogenes by Real-time Quantitative Loop-mediated Isothermal Amplification

Xiaoxiao Shan,Yaoqi Zhang,Zhigang Zhang,Miaorui Chen,Yongyu Su,Yingna Yuan,M. Jahangir Alam,He Yan,Lei Shi 한국식품과학회 2012 Food Science and Biotechnology Vol.21 No.1

The purpose of this study was to develop a real-time quantitative loop-mediated isothermal amplication (LAMP) method for the rapid, sensitive, and convenient detection of Listeria monocytogenes in food. The LAMP method could amplify the hlyA gene of L. monocytogenes successfully at 63oC with a loopamp real-time turbidimeter. The detection limits of the LAMP for hlyA gene were 6colony forming units (CFU)/tube. A standard curve was generated for L. monocytogenes LAMP by plotting the graph based different log CFU values of L. monocytogenes and time of positivity through real-time monitoring of the amplication. Then, the LAMP method was employed to test 94 retail food samples effectively. Sensitivity in detection of L. monocytogenes by the LAMP was higher than that of PCR and none of the conventional methodpositive samples was missed by the LAMP method.

Insight into the anti-corrosion performance of Acanthopanax senticosus leaf extract as eco-friendly corrosion inhibitor for carbon steel in acidic medium

Bokai Liao,Zhigang Luo,Shan Wan,Lijuan Chen 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-

In this work, the extract of acanthopanax senticosus leaf (ASLE), prepared using one-step pure waterextraction method, is firstly utilized as a sustainable eco-friendly corrosion inhibitor for carbon steel inacidic solutions. The corrosion inhibition efficiency is evaluated by weight loss method and electrochemicaltests, including electrochemical impedance spectroscopy and potentiodynamic polarization curve. The compositions of ASLE are analyzed using Fourier transform infrared spectroscopy, components andmicrostructures of corrosion products are characterized by scanning electron microscopy and X-ray photoelectronspectroscopy. Results indicate that ASLE is successfully prepared using the clean productionprocess, and it can act as an efficient mixed-type corrosion inhibitor for Q235 carbon steel in 1 mol/LHCl. The maximum corrosion inhibition efficiency can reach 98.79 % after 144 h immersion with the additionof 150 mg/L. ASLE also displays the superior long-term corrosion inhibition performance. The protectivehydrophobic adsorption film can effectively retard the invasion of aggressive ions and inhibit thecorrosion of carbon steel in acidic service occasions.

Thermo-mechanical Behaviour of Soft Clay between Operation and Shutdown of Submarine Hot Oil Pipeline

Kuanjun Wang,Hongwei Li,Kanmin Shen,Zhigang Shan,Weida Ni,Liuyuan Zhao,Hongyu Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.6

The interaction between the pipeline and the surrounding soil is a critical factor in thebuckling analysis of the pipeline operating at high temperatures and pressures. The heatingpipeline alters the temperature and induces excess pore pressure in the surrounding soil,which in turn affects the mechanical properties of the soil. Therefore, a comprehensiveunderstanding of the thermo-mechanical response of the soil surrounding the pipeline duringoperation and shutdown is essential. To address this issue, this study developed a temperaturecontrolledpipe model test device that simulates the heating and cooling cycle of the pipe andthe temperature field and pore pressure response of the surrounding kaolin clay. The testresults showed that the soil temperature at the closest location to the pipe (0.1D) reached apeak value of approximately 48.7°C when the pipe was heated from 12.5°C to 55°C. Thepeak temperature decreased with increasing distance, reaching 22.5°C at 0.875D. Heattransfer analysis using ABAQUS software revealed that the influence range of the pipeline onthe soil temperature field during the heating cycle was about 2D. Additionally, a parametricstudy focused on the thermal conductivity (λsoil) of kaolin, and the best-fit value wasdetermined to be 0.6 W/(m·°C). The excess pore pressures were generated in the kaolinsurrounding the pipes during the heating cycle, and negative pore pressures were observedafter cooling cycle. Furthermore, a theoretical solution for calculating the thermally inducedpore pressure was derived, and preliminary verification showed good agreement between thetheoretically computed and experimentally measured results. These findings provide valuableinsights into the thermo-mechanical response of the soil surrounding pipelines duringoperation and shutdown, which can improve the design and safety of oil and gas pipelines.

Feasibility analysis of bone density evaluation with Hounsfield unit value after fibula flap reconstruction of jaw defect

Yihui Yang,Yifan Kang,Yifan Yang,Mengkun Ding,Xiaofeng Shan,Zhigang Cai 대한악안면성형재건외과학회 2023 Maxillofacial Plastic Reconstructive Surgery Vol.45 No.-

Background Implant-supported dentures have become an essential means of restoring occlusal function after jaw reconstruction. Bone mineral density (BMD) may influence the success rate of implant denture restorations. This study aimed to explore whether the Hounsfield unit (HU) value can be used to monitor the changing trend of fibular BMD after jaw reconstruction. Results A total of 54 patients who underwent maxillar/mandibular reconstruction with a fibula flap were included in this study. There was a significant correlation between the HU value and BMD at 1 week, 3 months, and 6 months after surgery, and both were significantly correlated with follow-up time. The difference between each pair of absorption rates (DAR) was less than 10% in 66.7% and 75.9% of patients at 3 and 6 months; however, the DAR was more than 20% in 12% and 13.8% of patients at 3 and 6 months, respectively. Conclusions There is a significant correlation between HU value and BMD. The HU value can be used to roughly reflect the fibular BMD changing trend in a group of patients as opposed to an individual, and the HU value is not equivalent to BMD. Trial registration ChiCTR, ChiCTR2300069661, retrospectively registered on 22 March 2023. Retrospectively registered, https:// www. chictr. org. cn/ showp roj. html? proj= 188953.