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Microbial induced calcium carbonate precipitation (MICP) is a widespread phenomenon in nature. In this paper, various factors affecting microbial growth and urease activity were studied, including temperature, initial pH, urea concentration, Ca2+ concentration and gelling solution concentration, and the optimal process conditions for calcium carbonate preparation were determined. Subsequently, the changes of Ca2+ concentration, NH4+ concentration and pH value in alkaline medium with and without bacteria were studied carefully, and the dynamic process of calcium carbonate deposition was also revealed. Finally, the mineralization mechanism model of MICP was established by characterization and analysis of the precipitates. The results indicated that urease produced by bacteria in the metabolism process of bacteria could accelerate the hydrolysis rate of urea and the formation rate of carbonate. In addition, the bacterial cells themselves were negatively charged, which could adsorb Ca2+ with positive charge. Meanwhile, they could also be used as the nucleation sites to accelerate the generation of calcium carbonate.
Haihe Yi; Tianwen Zheng; Zhirong Jia; Tian Su; Chunguang Wang. Study on the influencing factors and mechanism of calcium carbonate precipitation induced by urease bacteria. Journal of Crystal Growth 2021, 564, 126113 .
AMA StyleHaihe Yi, Tianwen Zheng, Zhirong Jia, Tian Su, Chunguang Wang. Study on the influencing factors and mechanism of calcium carbonate precipitation induced by urease bacteria. Journal of Crystal Growth. 2021; 564 ():126113.
Chicago/Turabian StyleHaihe Yi; Tianwen Zheng; Zhirong Jia; Tian Su; Chunguang Wang. 2021. "Study on the influencing factors and mechanism of calcium carbonate precipitation induced by urease bacteria." Journal of Crystal Growth 564, no. : 126113.
In recent years, the research on bitumen has reached the nanometer level, but there are still some problems in the study of the relationship between the atomic force microscope (AFM) nano-morphology and ageing of bitumen. The purpose of this paper is to find out the effect of thermal oxygen ageing on the nano-morphology of bitumen. Atomic force microscope (AFM) test sample of bitumen was prepared in this paper. Area ratio of bee-like structure, roughness, and maximum amplitude were selected as the nano-morphological parameters of the bitumen. The calculation method of nano-parameters was also proposed. Bitumen with different ageing degrees was prepared by thin film oven test (TFOT). Nano-morphological parameters of bitumen with different ageing degrees were obtained by AFM and analyzed with NanoScope Analysis, and the relationships between nano-morphological parameters and bitumen technical indexes after ageing, such as penetration, ductility, softening point, and viscosity were analyzed. The test results show that the wave crests and wave troughs of the bee-like structure on the surface of the bitumen alternate, while the other areas are relatively flat. The bee-like structure continues to develop as the ageing time prolongs, and the number of bee-like structures decreases, but the volume and the undulation degree increase. With the ageing time prolonging, the nano-parameters of bitumen, such as the area ratio of bee-like structure, roughness, and maximum amplitude, show a trend of increasing gradually, but the increasing rates become smaller and smaller. During the ageing process of bitumen, with the increase of nano-morphological parameters (area ratio of bee-like structure, roughness, and maximum amplitude), penetration at 25 °C and ductility at 15 °C of the bitumen decrease, and softening point and viscosity at 60 °C increase. AFM testing technology and image analysis method in this paper can be used for a reference in the nano-scale study of bitumen.
Wengang Zhang; Ling Zou; Zhirong Jia; Fang Wang; Ying Li; Ping Shi; Zou; Jia; Wang; Li; Shi. Effect of Thermo-Oxidative Ageing on Nano-Morphology of Bitumen. Applied Sciences 2019, 9, 3027 .
AMA StyleWengang Zhang, Ling Zou, Zhirong Jia, Fang Wang, Ying Li, Ping Shi, Zou, Jia, Wang, Li, Shi. Effect of Thermo-Oxidative Ageing on Nano-Morphology of Bitumen. Applied Sciences. 2019; 9 (15):3027.
Chicago/Turabian StyleWengang Zhang; Ling Zou; Zhirong Jia; Fang Wang; Ying Li; Ping Shi; Zou; Jia; Wang; Li; Shi. 2019. "Effect of Thermo-Oxidative Ageing on Nano-Morphology of Bitumen." Applied Sciences 9, no. 15: 3027.
Risers are indispensable components of offshore platform systems that connect the wellhead at the sea bottom and to the platform at the sea surface and are normally made of high grade steel. Nowadays, fiber reinforced polymer (FRP) composite has been recognized as an attractive alternative riser material. Similarly to steel risers, FRP composite risers are also vulnerable to vortex induced vibration (VIV), and the effects of the composite makeup of these risers on VIV are the subject of the present investigation. Three risers (the tailored design composite riser, the composite riser with orthogonal reinforcements and the steel riser), three current velocities (0.36 m/s, 1.22 m/s and 2.13 m/s) and three water depths (12.5 m, 25 m and 37.5 m) are considered. In total, 9 study cases using orthogonal array (OA) sampling are investigated to study the risers’ VIV characteristics. The computational fluid dynamics (CFD) simulations with coupled fluid–structure interaction (FSI) are used to obtain the risers’ natural frequencies, global displacements, global stresses and the stress distributions in each composite lamina. The effect of 5 parameters (Etension, Ebending, L/Douter, tension force and current velocity) on the VIV amplitude in a cross flow direction of the risers is analyzed using Grey relational analysis (GRA) and the Grey relational grade of these parameters are: r 05 ( Velocity ) > r 03 ( L / D outer ) > r 04 ( Tension Force ) > r 01 ( E t e n s i o n ) > r 02 ( E b e n d i n g ) .
Chunguang Wang; Shiquan Ge; Justin W. Jaworski; Liping Liu; Zhirong Jia. Effects of Different Design Parameters on the Vortex Induced Vibration of FRP Composite Risers Using Grey Relational Analysis. Journal of Marine Science and Engineering 2019, 7, 231 .
AMA StyleChunguang Wang, Shiquan Ge, Justin W. Jaworski, Liping Liu, Zhirong Jia. Effects of Different Design Parameters on the Vortex Induced Vibration of FRP Composite Risers Using Grey Relational Analysis. Journal of Marine Science and Engineering. 2019; 7 (7):231.
Chicago/Turabian StyleChunguang Wang; Shiquan Ge; Justin W. Jaworski; Liping Liu; Zhirong Jia. 2019. "Effects of Different Design Parameters on the Vortex Induced Vibration of FRP Composite Risers Using Grey Relational Analysis." Journal of Marine Science and Engineering 7, no. 7: 231.
The increasing attraction of crude resources on the ocean floor leads to the development of risers, which are an indispensable component of an offshore oil and gas exploitation structure. High-grade steel is normally utilized for risers, however, fiber reinforced polymer (FRP) composite risers have become a feasible and economical alternative due to the desirable properties of the material. A comparative study of vortex-induced vibration (VIV) of FRP composite risers with two designed geometries were conducted and an X80 steel riser was used as the benchmark. The length to diameter ratios of all three risers were set to 100 and their VIV responses under different environmental situations, including the natural frequencies, global displacements, global stresses and the stress distributions in every composite layers, were obtained using computational fluid dynamics (CFD) simulation with coupled fluid–structure interaction. The VIV characteristics of both FRP composite risers and their distinction compared with that of steel risers were analyzed and discussed. From this paper, the dynamic characteristics in different environmental situations of VIV for FRP composite risers can be further understood.
Chunguang Wang; Shiquan Ge; Mingyu Sun; Zhirong Jia; Baomin Han. Comparative Study of Vortex-Induced Vibration of FRP Composite Risers with Large Length to Diameter Ratio Under Different Environmental Situations. Applied Sciences 2019, 9, 517 .
AMA StyleChunguang Wang, Shiquan Ge, Mingyu Sun, Zhirong Jia, Baomin Han. Comparative Study of Vortex-Induced Vibration of FRP Composite Risers with Large Length to Diameter Ratio Under Different Environmental Situations. Applied Sciences. 2019; 9 (3):517.
Chicago/Turabian StyleChunguang Wang; Shiquan Ge; Mingyu Sun; Zhirong Jia; Baomin Han. 2019. "Comparative Study of Vortex-Induced Vibration of FRP Composite Risers with Large Length to Diameter Ratio Under Different Environmental Situations." Applied Sciences 9, no. 3: 517.
Five types of material, styrene-butadiene-styrene block copolymer (SBS), ethyl-vinyl-acetate (EVA), naphthenic oil, maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH) and butylated hydroxytoluene (BHT) were used as the raw ingredients for manufacturing direct-to-plant SBS in this paper. Thirteen kinds of direct-to-plant SBS with different EVA/SBS and naphthenic oil/SBS were prepared as well as the processes diagrammatic sketch of dispersion and swelling of direct-to-plant SBS modifier in bitumen were discussed. Microscopic images of direct-to-plant SBS modified bitumen with different components were obtained using fluorescence microscopy. The micro-images were analysed and quantified with MATLAB software. The influence of key components on the micro-morphology of direct-to-plant SBS-modified bitumen is discussed, followed with the tests on melting points and the melting indexes of direct-to-plant SBS with different EVA/SBS and naphthenic oil/SBS. The performances test of bitumen and bituminous mixture modified by these direct-to-plant SBS were also conducted. Results show that, with the ratio improvement of EVA/SBS or naphthenic oil/SBS, the number of the pixel dot number of area (SBS) in microscopic images increased. Enlargement of the pixel dot number of centre line elongate and the structure fineness was observed, indicating that the dispersion and swelling effect of the SBS modifier in bitumen had been improved. Meanwhile, the macro index, such as the melting point and melting index of direct-to-plant SBS, was also improved corresponding to the increase of EVA/SBS ratio or naphthenic oil/SBS ratio. With the addition of EVA or naphthene oil content, penetration and ductility of direct-to-plant SBS modified bitumen received gradual enhancement, but the softening point and viscosity were found out to be decreased. The high-temperature and low-temperature performances of direct-to-plant SBS modified bituminous mixture can be effectively improved by adding EVA or naphthenic oil. By meeting the required performances of direct-to-plant SBS, modified bitumen and bituminous mixture, the component of direct-to-plant SBS is recommended as, SBS:EVA:naphthenic oil:EVA-g-MAH:BHT is 1:0.1–0.5:0.05–0.2:0.03:0.05. For the compatibleness of SBS with different bitumen are different, necessary tests verification is recommended to be carried out prior to usage.
Wengang Zhang; Zhirong Jia; Yixia Zhang; Kui Hu; Longting Ding; Fang Wang. The Effect of Direct-to-Plant Styrene-Butadiene-Styrene Block Copolymer Components on Bitumen Modification. Polymers 2019, 11, 140 .
AMA StyleWengang Zhang, Zhirong Jia, Yixia Zhang, Kui Hu, Longting Ding, Fang Wang. The Effect of Direct-to-Plant Styrene-Butadiene-Styrene Block Copolymer Components on Bitumen Modification. Polymers. 2019; 11 (1):140.
Chicago/Turabian StyleWengang Zhang; Zhirong Jia; Yixia Zhang; Kui Hu; Longting Ding; Fang Wang. 2019. "The Effect of Direct-to-Plant Styrene-Butadiene-Styrene Block Copolymer Components on Bitumen Modification." Polymers 11, no. 1: 140.
Risers are an indispensable component of offshore oil and gas exploitation structures, and they are vulnerable to vortex-induced vibration (VIV). Although many studies have been conducted to investigate the VIV characteristics of risers, the effects of combination of multiple parameters and the relative significance of each parameter on the risers’ VIV characteristics have rarely been considered. In this paper, 36 experimental cases were investigated to study the risers’ VIV characteristics due to the combination of multiple parameters. The natural frequencies, response microstrains and frequencies of VIV for the risers were obtained. Meanwhile, the effect of each parameter and the relative significance of these parameters on the amplitude of VIV in risers were calculated using grey relational analysis (GRA). The results show that all the parameters considered—i.e., material property (modulus and density), end condition, top tension force and flow velocity—affect risers’ VIV response, and the grey relational grade of these parameters are: r 02 ( velocity ) > r 04 ( constraints ) > r 05 ( density ) > r 03 ( tension ) > r 01 ( modulus ) .
Chunguang Wang; Yangyang Cui; Shiquan Ge; Mingyu Sun; Zhirong Jia. Experimental Study on Vortex-Induced Vibration of Risers Considering the Effects of Different Design Parameters. Applied Sciences 2018, 8, 2411 .
AMA StyleChunguang Wang, Yangyang Cui, Shiquan Ge, Mingyu Sun, Zhirong Jia. Experimental Study on Vortex-Induced Vibration of Risers Considering the Effects of Different Design Parameters. Applied Sciences. 2018; 8 (12):2411.
Chicago/Turabian StyleChunguang Wang; Yangyang Cui; Shiquan Ge; Mingyu Sun; Zhirong Jia. 2018. "Experimental Study on Vortex-Induced Vibration of Risers Considering the Effects of Different Design Parameters." Applied Sciences 8, no. 12: 2411.
Butylated hydroxytoluene (BHT) and titanium dioxide (TiO2) were used to improve the UV anti-aging performance of TPS modified bitumen in this article, and UV aging rate equation and UV aging equation were established based on the test results, which could be used to find the optimum BHT and TiO2 content. The results show that, 0.3% TiO2 and 0.1% BHT is the optimum formula in UV anti-aging performance of TPS modified bitumen based on UV aging rate equation and UV aging equation.
Wengang Zhang; Jun Shi; Zhirong Jia. The UV anti-aging performance of TPS modified bitumen. Petroleum Science and Technology 2018, 36, 1164 -1169.
AMA StyleWengang Zhang, Jun Shi, Zhirong Jia. The UV anti-aging performance of TPS modified bitumen. Petroleum Science and Technology. 2018; 36 (15):1164-1169.
Chicago/Turabian StyleWengang Zhang; Jun Shi; Zhirong Jia. 2018. "The UV anti-aging performance of TPS modified bitumen." Petroleum Science and Technology 36, no. 15: 1164-1169.
In order to improve the problem of the bad thermal storage stability of Styrene-Butadiene-Styrene Block Copolymer Modified Bitumen (SBS-modified bitumen), the vulcanization reaction was selected as the basic mechanism for the research and development of the stabilizer. Sulfur, tetramethylthiuram disulfide (TMTD), zinc oxide, butylated hydroxytoluene (BHT), kaolin (Al2O3·2SiO2·2H2O) and carbon-white (SiO2) were used as raw materials, and 32 kinds of components with different contents of raw materials were designed. The 48-h segregation softening point and other modified bitumen technical indicators, such as ductility, penetration, penetration index, viscosity, and so on, were tested and analyzed. The fluorescence microscope test was also conducted to explore the crosslinking situation based on the vulcanization reaction. The results show that the component with good performance of the SBS-modified bitumen stabilizer powder was S:TMTD:ZnO:BHT: Al2O3·2SiO2·2H2O = 60:16:4:20:1250 or S:TMTD:ZnO:BHT:SiO2 = 60:16:4:20:625. The optimum content of stabilizer powder was 0.9% (S/modified bitumen). The stabilizer was dry powder and can be directly put into bitumen. It can cross-link SBS and especially has an effect on preventing SBS segregation. The technical performance of SBS-modified bitumen with stabilizer powder, such as hot temperature performance, low temperature performance, anti-aging performance and thermal storage stability, all meet the relevant specifications.
Wengang Zhang; Longting Ding; Zhirong Jia. Design of SBS-Modified Bitumen Stabilizer Powder Based on the Vulcanization Mechanism. Applied Sciences 2018, 8, 457 .
AMA StyleWengang Zhang, Longting Ding, Zhirong Jia. Design of SBS-Modified Bitumen Stabilizer Powder Based on the Vulcanization Mechanism. Applied Sciences. 2018; 8 (3):457.
Chicago/Turabian StyleWengang Zhang; Longting Ding; Zhirong Jia. 2018. "Design of SBS-Modified Bitumen Stabilizer Powder Based on the Vulcanization Mechanism." Applied Sciences 8, no. 3: 457.