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Cheng Zhou,Shemin Zhu,Xiuming Wu,Bo Jiang,Tao Cen,Shubao Shen 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.3
Penicillin acylase (PA) is known to regulate the microenvironment of nanospores. In this study, nanopores containing chemically-modified macromolecules co-assembled with immobilized PA were constructed. We also investigated the various types of functionalized mesocellular siliceous foams (MCFs) commonly used for the immobilization of PA by measuring the catalytic performance and stability of each PA preparation. Amino-MCF activated by p-benzoquinone was chosen as the optimum support for PA immobilization. Successful modification of macromolecules was verified by FT-IR and ultraviolet (UV)spectroscopy. The specific activity of PA co-assembled with dextran 10 k was 99.1 U/mg, which was 1.5-fold that of pristine immobilized PA, while the optimum pH was shifted to neutral. Compared to pristine immobilized and free PA, the optimum temperatures for the modified PA were 5 and 10oC higher, respectively. The residual activity of the ficoll derivative of PA after treatment at 50oC for 6 h was 70%, and this was later increased to 214.5% compared to that of pristine immobilized PA. The dextran 10 k derivative of PA exhibited 90.2% residual activity after 25times of continuous use. The results show that chemicallymodified macromolecules co-assembled with PA in amino-MCF provided a suitable microenvironment for enzyme stability.
Zhiwei Xue,Shemin Zhu,Yuesong Shen,Shubao Shen,Chengliang Li 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.30 No.-
Promotional effects of Ce4+, La3+ and Nd3+ incorporations on FeCu2O3.5/ATS for decomposing N2O wereinvestigated. Results showed that all the ions especially La3+ can dramatically improve the catalyticperformance. FeCu2La1.5Ox/ATS, the optimal catalyst, can decompose 100% N2O at 550 8C. The formedperovskite-type LaFeO3 and spinel-type CuLa2O4 largely improved catalytic performance. The ionmodification increased N2O adsorption capacity, and La3+-doped catalyst enhanced desorption ability ofsurface oxygen. Both effects can accelerate the rate-determine steps of N2O decomposition reaction,promote catalytic performance. Moreover, the supported catalysts studied were economic efficiency forapplication.
Applicable range of the Reynolds equation for fluid flow in a rock fracture
In Wook Yeo,Shemin Ge 한국지질과학협의회 2005 Geosciences Journal Vol.9 No.4
The applicability of the Reynolds equation to fluidflow in rock fractures has recently been questioned. One issue isthat the Reynolds equation overestimates the transmissivity forrough fractures. Another issue is to delineate the range of fractureroughness over which the Reynolds equation is reasonably accu-rate. In this paper, the analysis was undertaken to examine therelationship between fracture geometry and the accuracy of theparameter, (bm/Λ)(A/Λ), where bm/Λ is the ratio of mean apertureto wavelength, representing roughness, and A/Λ is the ratio ofamplitude of oscilated fracture roughness to the wavelength, rep-resenting tortuosity. We found that when (bm/Λ)(A/Λ) is less than0.01, the Reynolds equation may yield accurate transmissivity pre-dictions.
Induced seismicity: the potential hazard from shale gas development and CO2 geologic storage
Jin-Yong Lee,Matthew Weingarten,Shemin Ge 한국지질과학협의회 2016 Geosciences Journal Vol.20 No.1
We present an overview of the current status of unconventional energy development, particularly of shale gas, and underground CO2 storage as a measure to mitigate greenhouse gas increase in the atmosphere. We review their potential to induce seismicity, which has caused debates among related energy enterprises, engineers, researchers, and environmental and public communities regarding their potential hazards. Studies show that fracking can be a problem in that it consumes abundant water, but the seismicity induced by fracking has not yet been observed to induce many felt earthquakes. However, massive wastewater injection, a part of the unconventional energy development process has caused M5.0+ earthquakes in the past as well as several recent and ongoing cases of induced seismicity. Large-scale CO2 injection as a part of carbon sequestration efforts in the near future has a high risk of inducing large earthquakes. Therefore, injection operations related to both unconventional energy development and carbon sequestration should be optimized and managed to mitigate the likelihood of an induced seismic event.
Cheng Zhou,Anming Wang,Zhiqiang Du,Shemin Zhu,Shubao Shen 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.4
Macromolecular reagents were co-assembled with penicillin acylase (PA) and immobilized in mesocellular siliceous foams (MCFs) to resemble living cells. Types and concentrations of macromolecules were studied. The catalytic characteristic and stability of PA preparations were also investigated. PA assembled with dextran 10 k in MCFs showed maximum specific activity, 1.32-fold of that of the solely immobilized PA. The optimum pH of dextran and BSA derivatives shifted to neutrality, and the optimum temperature increased by 10 oC. Also, Km of BSA derivative of PA declined 56.7% compared to solely immobilized PA, while the Kcat/Km of PA assembled with BSA was enhanced to 147%. After incubation at 50℃ for 6 h, residual activity of PA assembled with BSA exhibited 53.0%. The ficoll derivative showed 82.8% of its initial activity at 4 oC after 8-week storage. The results indicated that macromolecular reagents assembled with PA in MCFs could dramatically improve the catalytic performance and stability of im- mobilized enzyme.
Cheng Zhou,Shubao Shen,Bo Jiang,Zecui Sheng,Shemin Zhu 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.3
Chemically modified macromolecules were assembled with adsorptive trypsin in mesoporous silica foams (MCFs) to establish covalent linkage. Effects of catalytic properties and stability of immobilized trypsin were examined. The addition of chemically modified protein (BSA) and polysaccharide (ficoll) to the immobilized trypsin exhibited high coupled yield (above 90%) and relative activities (174.5% and 175.9%, respectively), showing no protein leaching after incubating for 10 h in buffers. They showed broader pH and temperature profiles, while the half life of thermal stability of BSA-modified preparation at 50 ℃ increased to 1.3 and 2.3 times of unmodified and free trypsin,respectively. The modified trypsin in aqueous-organic solvents exhibited 100% activity after 6 h at 50 ℃. The kinetic parameters of trypsin preparations and suitable pore diameter of MCFs warranted compatibility of covalent modification for substrate transmission. The covalent crowding modification for immobilized trypsin in nanopores establishes suitable and accessible microenvironment and renders possibility of biological application.
Managing injection-induced seismic risks
Lee, Kang-Kun,Ellsworth, William L.,Giardini, Domenico,Townend, John,Ge, Shemin,Shimamoto, Toshihiko,Yeo, In-Wook,Kang, Tae-Seob,Rhie, Junkee,Sheen, Dong-Hoon,Chang, Chandong,Woo, Jeong-Ung,Langenbruc American Association for the Advancement of Scienc 2019 Science Vol.364 No.6442
<P>Heat transported from deep within Earth's crust can be used to generate electricity or provide direct heating by circulating fluid through permeable fracture networks in hot rock. Because naturally permeable systems are rare, enhanced geothermal system (EGS) technology stimulates the creation of permeable pathways in otherwise impermeable rock by means of the injection of water under high pressure, creating new fractures and causing preexisting fractures to open. But several EGS projects have encountered problems of induced seismicity, particularly the moment magnitude (<I>M</I><SUB>w</SUB>) 5.5 earthquake in 2017 that occurred near an EGS drill site in Pohang, Republic of Korea (South Korea). Here we explore the implications of, and derive lessons from, the Pohang experience. The Pohang earthquake provides unequivocal evidence that EGS stimulation can trigger large earthquakes that rupture beyond the stimulated volume and disproves the hypothesis that the maximum earthquake magnitude is governed by the volume of injected fluids. Because that hypothesis tacitly underpins hazard-based methods used for managing induced seismicity, those methods must be revised and based on considerations of risk.</P>
The influence factors on CeSn0.8W0.6Ox/TiO2 for catalytic removals of NO, CO and C3H8
Guorong Sui,Zhiwei Xue,Dan Zhou,Yan Wang,Yuesong Shen,Yuhao Zong,Youlin Liu,Tai Qiu,Shemin Zhu 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.51 No.-
Series of CeSn0.8W0.6Ox/TiO2 catalysts were tested for selective catalytic reduction of NO and forsynergistic catalytic removals of CO and C3H8 from diesel engine exhaust. Results revealed that catalyst12%-CeSn0.8W0.6Ox/TiO2 calcined at 500 C exhibited the optimal catalytic performance for NH3-SCR ofNO. The catalyst obtained more than 90% NO conversion at a wide temperature range of 252–456 C. BothCO and C3H8 could be oxidized into CO2 by the optimized catalyst. Moreover, excellent redox property,rich surface acidity and big specific surface area were the promotional factors for good catalyticperformance in catalytic removals of NO, CO and C3H8.
Bo Yang,Yuesong Shen,Yun Su,Peiwen Li,Yan-Wei Zeng,Shubao Shen,Shemin Zhu 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.50 No.-
A novel Mn-Ce-Nb-Ox/P84 catalyticfilter for synergetic removal of particulates and NO was designed andprepared by a new method using functional foaming coating. Removal characteristics of nitrogen oxides(including catalyst loading amount, O2 concentration, NH3/NO molar ratio, H2O and SO2) andparticulates, were systematically studied. Results showed that the NO removal efficiency of catalyticfilter reached 95.3% at 200 C, as the catalyst loading amount,filtration velocity and mole ratio of NH3/NOwere set to be 450 g/m2, 1 m/min and 1, respectively. The removal characteristic of particulates of Mn-Ce-Nb-Ox/P84 catalyticfilter belonged surfacefiltration and the PM2.5 removal efficiency reached 99.98%.
She-Min Zhu,Da-Hai Zheng,Yuesong Shen,Yun-Shun Qiu,Bing Li,Yan-Wei Zeng,Shubao Shen,Shemin Zhu 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.24 No.-
Effects of catalyst loading amount, reaction temperature, O2 concentration, NH3/NO molar ratio and SO2 on low-temperature catalytic performance of the Mn–La–Ce–Ni–Ox (Mn/La/Ce/Ni = 2.5:2.5:1:1 in mol)/ PPS for NH3-SCR of NO were mainly studied. Results showed that the filter with catalyst loading amount of 250 g/m2 obtained more than 95% NO removal efficiency at 200 8C under filtration velocity of 1 m/min. The NO removal efficiency was still above 85% by injecting 300 ppm SO2 at 200 8C. Anyway, the Mn–La– Ce–Ni–Ox/PPS catalytic filter is promising to achieve the expectation of simultaneous removing particulate and NOx from low-sulfur flue gas in cement kiln.