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Traveling Waves for Nonlocal and Non-monotone Delayed Reaction-difusion Equations

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Acta Mathematica Sinica,English Series 2013年第11期29卷 2159-2180页

作者： zhi Ting XU pei Xuan WENG School of Mathematical Sciences South China Normal University

We study the existence of traveling wave solutions for a nonlocal and non-monotone delayed reaction-diffusion equation. Based on the construction of two associated auxiliary reaction diffusion equations with monotonicity and by using the traveling wavefronts of the auxiliary equations, the existence of the positive traveling wave solutions for c 〉 c. is obtained. Also, the exponential asymptotic behavior in the negative infinity was established. Moreover, we apply our results to some reactiondiffusion equations with spatio-temporal delay to obtain the existence of traveling waves. These results cover, complement and/or improve some existing ones in the literature.

关键词： Nonlocal non-monotone delayed reaction-diffusion equation traveling wave solutions auxiliary equation

One new bufadienolide biotransformed from cinobufagin by Cunninghamella elegans

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Chinese Chemical Letters 2008年第3期19卷 299-301页

作者： Li Qiao yu zhi Zhou Huan Chen Jia Qing Cao yue Hu pei School of Traditional Chinese Materia Medica Shenyang Pharmaceutical University Shenyang 110016 China

Cunninghamella elegans has been employed for the biotransformation of cinobufagin （1） to afford one metabolites. The structure of the transformation product has been characterized as 7β,12β-dihydroxylcinobufagin （2）. Product 2 is a new compound. In vitro cytotoxic activities of the biotransformation product and the substrate-cinobufagin have been assayed against HeLa; they all showed cytotoxic activities.

关键词： Biotransformation Cinobufagin 7β,12β-Dihydroxylcinobufagin Cunninghamella elegans

Wake Vortex Structure Characteristics of a Flexible Oscillating Fin

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Journal of Bionic Engineering 2008年第1期5卷 49-54页

作者： zhi-dong Wang pei Chen Xiao-qing Zhang School of Naval Architecture and Ocean Engineering Jiangsu University of Science and Technology Zhenjiang 212003 P. R.China Det Norske Veritas 1591 Hongqiao Road Shanghai 200336 P. R. China

We compute the wake of a two-dimensional and three-dimensional flexible fin in an unsteady flow field with heaving and pitching motions using FLUENT. Deflexion mode is used for a non-uniform cantilever beam with non-uniformly distributed load. The effect of chordwise deflexion length on the characteristics of propulsion is discussed for two-dimensional flexible fin. The thrust coefficient decreases, propulsive efficiency increases and the intensity of turbulence attenuates gradually as the deflexion length increases. For a three-dimensional flexible fin, the intensity of the vortex in the plane of symmetry is higher than that in the plane at 3/4 span length of the caudal fin. But the propulsive *** achieved is not what we expected with the given deflexion mode.

关键词： flexible fin deflexion length turbulence intensity structure of flow field

Visualization of adaptive polymer flow and displacement in medium-permeable 3D core-on-a-chip

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Petroleum Science 2023年第2期20卷 1018-1029页

作者： Yan Zhang Xue-zhi Zhao pei-Hui Han Li-yuan Zhang David A.Weitz yu-Jun Feng Polymer Research Institute State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065SichuanPR China EOR Laboratory Exploration&Development Research InstituteDaqing Oilfield Limited CompanyPetroChinaDaqing163712HeilongjiangPR China School of Engineering and Applied Sciences Harvard UniversityCambridge02138United States School of Petroleum Engineering China University of PetroleumQingdao266580ShandongPR China

Polymer flooding has been witnessed an effective technology for enhancing oil recovery from medium-to low-permeability reservoirs;however, direct visualization of polymer solution flow in such reservoir condition is still lacking. In this work, a three-dimensional (3D) core-on-a-chip device with a permeability of around 200 mD was prepared and employed to visualize the pore-scale flow and displacement of a self-adaptive polymer (SAP, 8.7 × 106 g·mol−1)−whose microscopic association structure and macroscopic viscosity can reversibly change in response to shear action−versus partially hydrolyzed polyacrylamide (HPAM), by recording their flow curves, monitoring dynamic transportation process via particle imaging velocimetry, and building 3D structure of remaining oil. The results show that, in single-phase flow, all polymer solutions exhibit flow thinning and then thickening regions as flow rate increases, but the transition between two regimes occurs at a small Weissenberg number (10−3−10−1) in this medium-permeable condition. In contrast to HPAM-1 with close weight-average molecular weight (Mw), the adaptive character not only extends SAP's shear-govern region, allowing SAP to propagate piece by piece and achieve higher accessible pore volume, but it also enhances the elastic resistibility of polymer in the extension-dominated regime, increasing the microscopic displacement efficiency. These two effects result in 1.5–3 times more oil recovery factor for SAP than for HPAM-1. Regarding ultra-high-Mw HPAM-2 (25 × 106 g·mol−1), plugging and chain degradation do occur, thus producing lower oil recovery than SAP. This work provides a direct approach for in-situ assessment of polymer-based displacing system under a more authentic condition of practical reservoirs.

关键词： Polymer flooding Medium-permeable transparent media Adaptive polymer In-situ rheology Particle imaging velocimetry

Effects of thermophoresis on Brownian coagulation of spherical particles over the entire particle size regime

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Particuology 2022年第8期20卷 8-17页

作者： Kaiyuan Wang pei Wang Suyuan yu Institute of Applied Physics and Computational Mathematics Bejing 100094.China Center forCombustionEergy.Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energyand PowerEngineeringTsinghua UniversityBejing 100084.China Smoore International Holdings Ltd.Shenzhen 518102 China

In many energy and combustion *** experience large temperature gradients,which can affect the coagulation process due to *** study presents a rigorous theory of thermophoretically modified Brownian coagulation in the entire particle size *** theoretical derivations are based on the kinetictheory forthe free-molecular regime and the harmonic mean method for the transition *** coagulation kernels in different size regimes can be expressed as the basic Brownian coagulation kernel times an enhancement factor,The enhancement factor represents the coagulationrate enhancement induced by thermophoresis and is a function of specific dimensionless *** on the enhancement factor,the thermophoretic enhancement effects on particle coagulation are further analyzed under a wide range of gas and particle *** results show that thermophoretic enhancement effects are ignorable in the free-molecular regime,but need to be considered in the continuum regime and the transition *** addition,the enhancement effects increase significantly with increase of gas temperature and temperature gradient while decrease with increase of gas *** present study can improve understanding ofthermophoretic effects on Brownian coagulation in the entire size regime and provide a useful tool to calculate the coagulation rates in presence of thermophoresis.

关键词： Thermophoresis Brownian coagulation Enhancement factor Knudsen number

Deep original information preservation by applying in-situ film formation technology during coring

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Petroleum Science 2022年第3期19卷 1322-1333页

作者： Liang-yu Zhu Tao Liu zhi-yu Zhao Yi-Fan Wu Dong-Sheng Yang Xiang-Chao Shi zhi-Qiang Liu Fei-Fei Lu pei Qin Xiao-Liang Gao State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China Institute of New Energy and Low-Carbon Technology Sichuan UniversityChengdu610065SichuanChina College of Polymer Science and Engineering Sichuan UniversityChengdu610065China Zaoshenzhuang Village Hancheng TowuLubei DistrictTangshan064002HebeiChina Xi'an Research Institute China Coal Technology&Engineering Group CorpXi'an710077China State Key Laboratory of Coking Coal Exploitation and Comprehensive Utilization Pingdingshan467000China Institute of Coal Mining and Utilization Pingdingshan Tianan Coal Mining Co.LTD.Pingdingshan467000China

Accurately obtaining the original information of an in-situ rock via coring is a significant guiding step for exploring and developing deep oil and gas *** is difficult for traditional coring technology and equipment to preserve the original information in deep *** study develops a technology for insitu substance-preserved(ISP),moisture-preserved(IMP),and light-preserved(ILP)*** technology stores the original information in real time by forming a solid sealing film on the in-situ sample during *** study designed the ISP-IMP-ILP-Coring process and *** addition,an ISP-IMP-ILPCoring process simulation system was *** effects of temperature,pressure,and film thickness on the quality of the in-situ film were investigated by performing in-situ film-forming simulation experiments.A solid sealing film with a thickness of 2-3 mm can be formed;it completely covers the core sample and has uniform *** film maintains good ISP-IMP-ILP properties and can protect the core sample in the in-situ environment *** study verifies the feasibility of“film formation during coring”technology and provides strong support for the engineering application of ISP-IMP-ILPCoring technology.

关键词： Deep resource exploitation Original information ISP-IMP-ILP-Coring Solid sealing film In-situ film-forming Film formation during coring

Adsorption of uranium(Ⅵ) onto amidoxime-functionalized ultrahigh molecular weight polyethylene fibers from aqueous solution

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Nuclear Science and Techniques 2017年第7期28卷 97-104页

作者： Chun-yu Xie Shi-pei Jing yu Wang Xiao Lin Hong-Liang Bao Cheng-zhi Guan Chan Jin Jian-Qiang Wang Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China University of Chinese Academy of Sciences Beijing 100049China

Amidoxime-functionalized ultra-high molecular weight polyethylene fibers(UHMWPEF-AO) were used to absorb uranium U(VI) from aqueous *** this paper,we study effects of pH,initial U(VI) concentration,contact time,and temperature on U(VI) adsorption by *** adsorption process agrees well with pseudo-second-order and Langmuir *** exhibits excellent adsorptive performance for U(VI)with a maximum adsorption capacity of 176.12 mg/g at pH4 and 298 *** structures of UHMWPEF-AO and U(VI)-loaded UHMWPEF-AO are characterized by FT-IR and nano-CT.U(VI)-loaded UHMWPEF-AO is sintered after adsorption process to recycle absorbed U(VI).Powders collected after sintering process are examined by scanning electron microscopy and X-ray *** results indicate that UHMWPEF-AO is a promising candidate to remove U(VI) from uranium aqueous solutions.

关键词：超高分子量聚乙烯纤维吸附性能偕胺肟基铀(Ⅵ) 水溶液扫描电子显微镜烧结过程 FT-IR

Engineering DNA Materials for Sustainable Data Storage Using a DNA Movable-Type System

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Engineering 2023年第10期29卷 130-136页

作者： Zi-Yi Gong Li-Fu Song Guang-Sheng pei yu-Fei Dong Bing-zhi Li Ying-Jin yuan Frontiers Science Center for Synthetic Biology&Key Laboratory of Systems Bioengineering(Ministry of Education) School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China School of Biomedical Informatics The University of Texas Health Science Center at Houston(UTHealth)HoustonTX 77030USA

DNA molecules are green materials with great potential for high-density and long-term data ***,the current data-writing process of DNA data storage via DNA synthesis suffers from high costs and the production of hazards,limiting its practical ***,we developed a DNA movable-type storage system that can utilize DNA fragments pre-produced by cell factories for data *** this system,these pre-generated DNA fragments,referred to herein as“DNA movable types,”are used as basic writing units in a repetitive *** process of data writing is achieved by the rapid assembly of these DNA movable types,thereby avoiding the costly and environmentally hazardous process of de novo DNA *** this system,we successfully encoded 24 bytes of digital information in DNA and read it back accurately by means of high-throughput sequencing and decoding,thereby demonstrating the feasibility of this *** its repetitive usage and biological assembly of DNA movable-type fragments,this system exhibits excellent potential for writing cost reduction,opening up a novel route toward an economical and sustainable digital data-storage technology.

关键词： Synthetic biology DNA data storage DNA movable types Economical DNA data storage

Effect of stabilizing treatment on microstructure and stress rupture properties of phosphorus microalloyed Inconel 706 alloy

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Journal of Iron and Steel Research International 2023年第8期30卷 1613-1621页

作者： Sha Zhang yu-chao Wu yu Lil Zhong-pei Dail Dan Jia Yan-fei Xu Guang-sheng Zeng zhi-ming Guo Jian Liul College of Mechanical&Electrical Engineering Changsha UniversityChangsha 410022HunanChina Hunan Engineering Research Center of Research and Development of Degradable Materials and Molding Technology Changsha UniversityChangsha 410022HunanChina Changsha Kaiple Technology Co. Ltd.Changsha 410114HunanChina Institute of Metal Research Chinese Academy of SciencesShenyang 110016LiaoningChina

The microstructure and stress rupture properties of Inconel 706 alloy microalloyed with phosphorus are examined under stabilizing and unstabilizing heat treatment *** was found that applying the stabilizing treatment resulted in a 98% increment in the stress rupture life and a 215% increment in the elongation tested at 650℃/690 MPa for the alloy compared to that under the unstabilizing heat treatment *** stabilizing treatment led to the precipitation of rod-shaped and needle-shaped n phases at the grain *** of γ'-γ" co-precipitates in the grain interior were noncompact form and compact form for the alloy under unstabilizing and stabilizing heat treatment conditions,*** on the microstructure characterizations,the improvement of stress rupture properties by the stabilizing treatment was attributed to the precipitation of n phases at the grain boundaries,which can hinder cracks initiation and propagation and relieve the stress concentration.

关键词： Superalloy Stabilization ηphase γ'-γ"co-precipitate Stress rupture property