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43篇 您的检索式:作者名="Renpeng"
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1Review on photocatalytic and electrocatalytic artificial nitrogen fixation for ammonia synthesis at mild conditions: Advances,challenges and perspectives显示文摘The ammonia synthesis from nitrogen and water under ambient conditions is one of the most inviting but challenging reaction routes.Although nitrogen is abundant in the atmosphere and the ammonia synthesis reaction is exothermic on the thermodynamics,the conversion of N2 to ammonia is actually hard to proceed owing to the chemical inertness and stability of N2 molecules.In industry,ammonia synthesis is carried out by the Haber-Bosch process under harsh conditions (300-500 ℃,20-30 MPa) associated with the requirement of substantial energy input and the enormous emission of greenhouse gases (e.g.,CO2).Recently,a growing number of studies on photo(electro)catalytic and electrocatalytic nitrogen reduction reaction (NRR) in aqueous solution have attracted extensive attention,which holds great promise for nitrogen fixation under room temperature and atmospheric pressure.However,the very low efficiency and ambiguous mechanism still remain as the major hurdles for the development of photochemical and electrochemical NRR systems.Here we provide an overview of the latest progresses,remaining challenges and future prospects in photocatalytic and electrocatalytic nitrogen fixation.Moreover,this review offers a helpful guidance for the reasonable design of photocatalysts and electrocatalysts towards NRR by combining theory predictions and experiment results.We hope this review can stimulate more research interests in the relatively understudied but highly promising research field of NRR.Xiaolan Xue Renpeng Chen Changzeng Yan Peiyang Zhao Yi Hu Wenjun Zhang Songyuan Yang Zhong Jin 2019Nano Research2019,12,6:20
2Prediction of shield tunneling-induced ground settlement using machine learning techniques显示文摘Predicting the tunneling-induced maximum ground surface settlement is a complex problem since the settlement depends on plenty of intrinsic and extrinsic factors.This study investigates the efficiency and feasibility of six machine learning(ML)algorithms,namely,back-propagation neural network,wavelet neural network,general regression neural network(GRNN),extreme learning machine,support vector machine and random forest(RF),to predict tunneling?induced settlement.Field data sets including geological conditions,shield operational parameters,and tunnel geometry collected from four sections of tunnel with a total of 3.93 km are used to build models.Three indicators,mean absolute error,root mean absolute error,and coefficient of determination the(7?2)are used to demonstrate the performance of each computational model.The results indicated that ML algorithms have great potential to predict tunneling-induced settlement,compared with the traditional multivariate linear regression method.GRNN and RF algorithms show the best performance among six ML algorithms,which accurately recognize the evolution of tunneling-induced settlement.The correlation between the input variables and settlement is also investigated by Pearson correlation coefficient.Renpeng CHEN Pin ZHANG Huaina WU Zhiteng WANG Zhiquan ZHONG 2019Frontiers of Structural and Civil Engineering2019,13,6:20
3Analysis of diffusion-adsorption equivalency of landfill liner systems for organic contaminants显示文摘The equivalence between multilayered barriers regarding diffusion and adsorption was studied. The bottom boundary of the liner system is defined by assuming concentration continuous and flux continuous conditions of the contaminant between the bottom liner layer and the underlying soil. Five different liner systems were compared in terms of solute breakthrough time. The results of the analysis showed that breakthrough time of the hydrophobic organic compounds for a 2-meter-thick compacted clay liner (CCL) could be 3-4 orders of magnitude is greater than the breakthrough time for a geosynthetic clay liner (GCL) composite liner. The GM/GCL and GM/CCL composite liner systems provide a better diffusion barrier for the hydrophilic organic compounds than that for the hydrophobic compounds due to their different Henry's coeffcient. The calculated breakthrough times of the organic contaminants for the Chinese standard liner systems were found to be generally greater than those for the GCL alternatives, for the specific conditions examined. If the distribution coeffcient increases to 2.8 for the hydrophobic compounds or 1.0 for the hydrophilic compounds, the thickness of the attenuation layer needed to achieve the same breakthrough time as the standard liner systems can be reduced by a factor of about 1.9-2.4. As far as diffusive and adsorption contaminant transport are concerned, GM or GCL is less effective than CCL.XIE Haijian, CHEN Yunmin, KE Han, TANG Xiaowu, CHEN Renpeng MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Zhejiang University, Hangzhou 310027, China. 2009Journal of Environmental Sciences2009,21,4:8
4Shear wave velocity-based evaluation and design of stone column improved ground for liquefaction mitigation显示文摘The evaluation and design of stone column improvement ground for liquefaction mitigation is a challenging issue for the state of practice. In this paper, a shear wave velocity-based approach is proposed based on the well-defined correlations of liquefaction resistance(CRR)-shear wave velocity(V_s)-void ratio(e) of sandy soils, and the values of parameters in this approach are recommended for preliminary design purpose when site specific values are not available. The detailed procedures of pre-and post-improvement liquefaction evaluations and stone column design are given. According to this approach, the required level of ground improvement will be met once the target V_s of soil is raised high enough(i.e., no less than the critical velocity) to resist the given earthquake loading according to the CRR-V_s relationship, and then this requirement is transferred to the control of target void ratio(i.e., the critical e) according to the V_s-e relationship. As this approach relies on the densification of the surrounding soil instead of the whole improved ground and is conservative by nature, specific considerations of the densification mechanism and effect are given, and the effects of drainage and reinforcement of stone columns are also discussed. A case study of a thermal power plant in Indonesia is introduced, where the effectiveness of stone column improved ground was evaluated by the proposed V_s-based method and compared with the SPT-based evaluation. This improved ground performed well and experienced no liquefaction during subsequent strong earthquakes.Zhou Yanguo Sun Zhengbo Chen Jie Chen Yunmin Chen Renpeng 2017Earthquake Engineering and Engineering Vibration2017,16,2:7
5Present Terrestrial Heat Flow Measurements of the Geothermal Fields in the Chagan Sag of the YingenEjinaqi Basin,Inner Mongolia,China显示文摘Owing to the lack o f terrestrial heat flow data, studying lithospheric thermal structure and geodynamics of the Yingen-Ejinaqi Basin in Inner Mongolia is limited. In this paper, the terrestrial heat flow o f the Chagan sag in the YingenEjinaqi Basin were calculated by 193 system steady-state temperature measurements of 4 wells, and newly measuring 62 rock thermal conductivity and 20 heat production rate data on basis o f the original 107 rock thermal conductivity and 70 heat production data. The results show that the average thermal conductivity and heat production rate are 2.11 ±0.28 W/(m.K) and2.42±0.25 nW/m^3 in the Lower Cretaceous o f the Chagan sag. The average geothermal gradient from the Lower Suhongtu 2 Formation to the Suhongtu 1 Fonnation is 37.6 °C/km, and that o f the Bayingebi 2 Formation is 27.4 °C/km. Meanwhile, the average terrestrial heat flow in the Chagan sag is 70.6 mW/m^2. On the above results, it is clear that there is an obvious negative correlation between the thermal conductivity o f the stratum and its geothermal gradient. Moreover, it reveals that there is a geothermal state between tectonically stable and active areas. This work may provide geothermal parameters for further research o f lithospheric thermal structure and geodynamics in the Chagan sag.FENG Renpeng ZUO Yinhui YANG Meihua ZHANG Jiong LIU Zhi ZHOU Yongshui HAO Qingqing 2019Acta Geologica Sinica(English Edition)2019,93,2:6
6Controlled growth and photoconductive properties of hexagonal SnS2 nanoflakes with mesa-shaped atomic steps显示文摘We demonstrated the controlled growth of two-dimensional (2D) hexagonal tin disulfide (SnS2) nanoflakes with stacked monolayer atomic steps. The morphology was similar to flat-topped and step-sided mesa plateaus or step pyramids. The SnS2 nanoflakes were grown on mica substrates via an atmospheric-pressure chemical vapor deposition process using tin monosulfide and sulfur powder as precursors. Atomic force microscopy (AFM), electron microscopy, and Raman characterizations were performed to investigate the structural features, and a sequential layer-wise epitaxial growth mechanism was revealed. In addition, systematic Raman characterizations were performed on individual SnS2 nanoflakes with a wide range of thicknesses (1-100 nm), indicating that the A1g peak intensity and Raman shifts were closely related to the thickness of the SnS2 nanoflakes. Moreover, photoconductive AFM was performed on the monolayer-stepped SnS2 nanoflakes, revealing that the flat surface and the edges of the SnS2 atomic steps had different electrical conductive properties and photoconductive behaviors. This is ascribed to the dangling bonds and defects at the atomic step edges, which caused a height difference of the Schottky barriers formed at the interfaces between the PtIr-coated AFM tip and the step edges or the flat surface of the SnS2 nanoflakes. The 2D SnS2 crystals with regular monolayer atomic steps and fast photoresponsivity are promising for novel applications in photodetectors and integrated optoelectronic circuits.Yi Hu Tao Chen Xiaoqi Wang Lianbo Ma Renpeng Chen Hongfei Zhu Xin Yuan Changzeng Yan Guoyin Zhu Hongling Lv Jia Liang Zhong Jin Jie Liu 2017Nano Research2017,10,4:5
7Experimental study on dynamic load magnification factor for ballastless track-subgrade of high-speed railway显示文摘The magnitude of dynamic load produced by high-speed trains depends on many factors,of which train speed is the most critical one.However,it is quite difficult to determine the effect of train speed on dynamic load using the theoretical methods due to the complexity of the interaction between vehicle and track-subgrade.Thus large-scale model test has gradually become an important approach for studying dynamic responses of ballastless track-subgrade of high-speed railway.In this study,a full-scale model of ballastless track-subgrade was constructed in accordance with the design and construction standards for Shanghai-Nanjing intercity high-speed railway line firstly.Then,the dynamic strain of slab and the dynamic earth pressure of subgrade were measured by conducting single wheel axle excitation test.In addition,the relationship between the dynamic load magnification factor(DLF) and the train speed was obtained.Finally,the DLF of track-subgrade under different train speeds was proposed,similar to that given by German Railway Standard.Renpeng Chen Xing Zhao Zuozhou Wang Hongguang Jiang Xuecheng Bian 2013Journal of Rock Mechanics and Geotechnical Engineering2013,5,4:5
8Experimental study on applicability of using time-domain reflectometry to detect NAPLs contaminated sands显示文摘Underground contamination by non-aqueous phase liquids (NAPLs) becomes increasingly serious. Rapid and reliable detection of contaminated zone and degree is the first step to site remediation. In this paper, diesel and fine sand are used as experiment materials to investigate the applicability of using time-domain reflectometry (TDR) to detect LNAPLs contamination. The major work includes: measurement of dielectric constant and electrical conductivity for the diesel-water-air-sand mixtures; measurement of reflection waveform and dielectric constant for specimens with a diesel contaminated layer being sandwiched in sand. The experimental results show the followings: A significant decrease in both dielectric constant and electrical conductivity is observed for the diesel-water-air-sand mixtures when diesel displaces the pore water, and the content of diesel can be calculated by the model; insignificant change in dielectric properties is measured when diesel only displaces the pore gas; when the diesel contaminated sand is sandwiched between two saturated sand layers, the interfaces of the diesel contaminated layer can be identified by analyzing the reflection waveform; for field application, TDR method is valid for the case that LNAPLs seep into saturated sand layer, and the applicability of TDR method in vadose zone depends on the initial saturation of the sand layer. The findings obtained in this paper provide a guidance for the use of TDR for the field investigation of NAPLs contaminated site.ZHAN LiangTong MU QingYi CHEN YunMin CHEN RenPeng 2013Science China(Technological Sciences)2013,56,6:5
9Seismic stability and permanent displacement of landfill along liners显示文摘The three-part wedge limit equilibrium method for seismic stability analysis of the landfill along liners is presented. The approximate solutions of the factor of safety and the yield acceleration coefficient are obtained. Parametric studies show that the interface strength of liners, the shear strength of waste and the height of retaining wall can influence the seismic stability of landfill along liners. The density and the shear wave velocity of the field waste are obtained by the borehole investigation and the spectral analysis of surface wave (SASW), respectively. The strain-dependent shear modulus and damping ratio of the artifical waste are obtained by the moderate-scale dynamic triaxial tests. The onedimensional (1D) equivalent linear dynamic response analysis is used to calculate the horizontal equivalent seismic coefficient-time history of the sliding landfill during earthquake. The seismic permanent displacement of the landfill along liners with different site conditons and heights is evaluated by the Newmark method. The catculated results show that ratio of ky /kmax, site conditions, the amplitude and frequency content of the bedrock motion can affect the seismic permanent displacement of the landfill along liners in some degree. Finally, the seismic stability and permanent displacements of three expanded configurations of a certain landfill case are analyzed.CHEN YunMin GAO Deng ZHU Bin CHEN RenPeng 2008Science China(Technological Sciences)2008,51,4:4
10Structural Characterization of Glucan Produced by Lactobacillus sake L-7 from Sausage显示文摘A linear glucan was produced by Lactobacillus sake L-7 isolated from homemade sausage. Cultivation of the strain in Man–Rogosa–Sharpe(MRS) medium containing 50 g/L sucrose yielded 5.3 g/L of purified exopolysaccharide(EPS). The EPS was characterized by gas chromatography(GC), Fourier-transform infrared(FT-IR) spectroscopy, high-performance sizeexclusion chromatography(HPSEC), nuclear magnetic resonance(NMR) spectroscopy, and scanning electron microscopy(SEM). The monosaccharide composition of the EPS was glucose, and its molecular weight was 1 × 10~7 Da. The FT-IR and NMR spectra revealed that the L-7 EPS was a linear glucan with α-(1 → 6) glucosidic bonds. SEM images of the dried EPS revealed a hollow tubular structure. The water solubility index and water holding capacity of L-7 EPS were 96 and 272%, respectively. The results of hydrolysis indicated that L-7 EPS was not susceptible to hydrolysis by physiological barriers and can be used as a soluble dietary fiber with health benefits. All these characteristics suggest that L-7 EPS might have potential applications in the food, cosmetic, and pharmaceutical industries.Fang Feng Qingqing Zhou Yanfang Yang Fangkun Zhao Renpeng Du Ye Han Zhijiang Zhou 2019Transactions of Tianjin University2019,25,1:3
11High-performance Li-ion capacitor based on black-TiO2-x/graphene aerogel anode and biomass-derived microporous carbon cathode显示文摘Lithium-ion capacitor (LIC) has been regarded as a promising energy storage system with high powder density and high energy density.However,the kinetic mismatch between the anode and the cathode is a major issue to be solved.Here we report a high-performance asymmetric LIC based on oxygen-deficient black-TiO2-x/graphene (B-TiO2-x/G) aerogel anode and biomass derived microporous carbon cathode.Through a facile one-pot hydrothermal process,graphene nanosheets and oxygen-vacancy-rich porous B-TiO2-x/G nanosheets were self-assembled into three-dimensional (3D) interconnected B-TiO2-x/G aerogel.Owing to the rich active sites,high conductivity and fast kinetics,the B-TiO2-x/G aerogel exhibits remarkable reversible capacity,high rate capability and long cycle life when used as anode material for lithium ion storage.Moreover,density functional theory (DFT) calculation reveals that the incorporation of graphene nanosheets can reduce the energy barrier of Li^+ diffusion in B-TiO2-x.The asymmetric LIC based on B-TiO2-x/G aerogel anode and naturally-abundant pine-needles derived microporous carbon (MPC) cathode work well within a large voltage window (1.0-4.0 V),and can deliver high energy density (166.4 Wh·kg^-1 at 200 mA·g^-1),and high power density (7.9 kW·kg^-1 at 17.1 Wh·kg^-1).Moreover,the LIC shows a high capacitance retention of 87% after 3,000cycles at 2,000 mA·g^-1.The outstanding electrochemical performances indicate that the rationally-designed LICs have promising prospect to serve as advanced fast-charging energy storage devices.Guoyin Zhu Lianbo Ma Huinan Lin Peiyang Zhao Lei Wang Yi Hu Renpeng Chen Tao Chen Yanrong Wang Zuoxiu Tie Zhong Jin 2019Nano Research2019,12,7:2
12Isolation, Purification, and Characterization of Exopolysaccharide Produced by Leuconostoc Citreum N21 from Dried Milk Cake显示文摘A strain with high production of exopolysaccharide(EPS) was isolated from dried milk cake(a traditional fermented food from Inner Mongolia). The strain was called N21 and later identified as Leuconostoc citreum( Leu. citreum). The strain was cultured in Man-Rogosa-Sharpe medium containing 50 g/L of sucrose for 48 h at 30 °C and the EPS purified, with a yield of 24.5 g/L. An average molecular weight of 6.07 × 10~6 g/mol was determined by high-performance size-exclusion chromatography. The structure of the purified EPS was investigated through gas chromatography, ~1H and ^(13)C nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. The results demonstrated a polysaccharide composed of D-glucopyranose units in a linear chain with consecutive α(1 → 6) linkages. No branching was found in the structure of the exopolysaccharide. The purified EPS showed high water solubility and emulsibility. Based on the thermogravimetric curve, the degradation temperature of the EPS was 308.47 °C, which suggested that the dextran in the study exhibited high thermal stability. The results indicated that Leu. citreum N21 could be widely used to produce linear EPS and that the EPS has potential applications in food science and processing as a food additive.Yanfang Yang Fang Feng Qingqing Zhou Fangkun Zhao Renpeng Du Zhijiang Zhou Ye Han 2019Transactions of Tianjin University2019,25,2:2
13Three-dimensional spongy framework as superlyophilic, strongly absorbing,and electrocatalytic polysulfide reservoir layer for high-rate and long-cycling lithiumsulfur batteries显示文摘In the development of lithium-sulfur (Li-S)batteries,various approaches have been adopted to enhance the electronic conductivity of the sulfur cathode and alleviate the shuttle effect of polysulfides;however,the strategies providing efficient solutions are still limited.To further improve the electrochemical performance of Li-S batteries,in this work we propose a new strategy involving the incorporation of a three-dimensional functional spongy framework as polysulfide reservoir layer,with strong absorbability and electrocatalytic activity towards sulfur species.The spongy framework has a hierarchical architecture composed of highly conductive Ni foam/graphene/carbon nanotubes/MnO2nanoflakes (NGCM).The strongly interconnected Ni foam,graphene,and carbon nanotubes of the NGCM sponge facilitate electron transfer during discharge/charge processes;moreover,the superlyophilic properties of the NGCM sponge ensure good wettability and interface contact with the Li-S electrolyte,and the porous MnO2nanoflakes provide strong chemisorptive and electrocatalytic effects on polysulfides (as confirmed theoretically and experimentally).The NGCM sponge, serving as a polysulfide reservoir layer attached on a conventional sulfur-mixed carbon nanotubes (S/CNTs)cathode,can provide improved reversible capacity, rate capability (593mAh·g^-1at 3.0C),and cycling stability.In addition,the self-discharge rate is greatly reduced,owing to the efficient conservation of polysulfides in the NGCM spongy framework.Lianbo Ma Guoyin Zhu Wenjun Zhang Peiyang Zhao Yi Hu Yanrong Wang Lei Wang Renpeng Chen Tao Chen Zuoxiu Tie Jie Liu Zhong Jin 2018Nano Research2018,11,12:2
14Production of Pectinolytic Enzymes by Two Bacillus spp. Strains and Their Application in Flax Degumming显示文摘This study demonstrated that Bacillus licheniformis HDYM-03 and Bacillus megaterium HDYM-09, isolated from a liquid sample of fl ax retting pool, were able to produce pectinolytic enzymes using polysaccharides as substrates. Bacillus megaterium HDYM-09 produced pectin lyase that exhibited the highest activity of 2116.71 ± 11.55 U/mL. Bacillus licheniformis HDYM-03 produced pectate lyase that exhibited the highest activity of 611.21 ± 14.54 U/mL. Based on these fi ndings, we constructed four retting systems to degrade the pectin substance. The results showed that the content of galacturonic acid in the mixed system was 529.21 μg/mL, the content of reducing sugar was 98.14 mg/mL, and the weight loss ratio of cells reached 19.49%, which were signifi cantly higher than those in other systems. The mixed system has more advantages, and the utilization rate of degumming was higher, which further ensured that the degumming can be carried out effi ciently and quickly. The mixed system exhibits feasible applications in the fi ber and textile industry.Jingping Ge Zhiyu Yang Renpeng Du Li Zhang Wenxiang Ping Dan Zhao 2019Transactions of Tianjin University2019,25,4:2
15Stability control of underground construction显示文摘这份报纸为地下的建设的不稳定性论述原因。为了在整个构造期间知道失败机制,处理,一个研究框架基于实验和数字分析多尺度被建立。在稳定性控制的话题的一些有希望的方面也在论文被给。Chen Renpeng Tang Lvjun Chen Yunmin 2010Engineering Sciences2010,8,4:2
16Synthesis of polydopamine‐coated graphene–polymer nanocomposites via RAFT polymerization显示文摘Renpeng Gu William Z. Xu Paul A. Charpentier 2013J. Polym. Sci. Part A: Polym. Chem2013,,18:1
17Overexpression of Hdac6 extends reproductive lifespan in mice显示文摘Xiaoxi Zhang Jiao Yang Haiying Wang Renpeng Guo Yu Yin Dongdong Zhang Qian Zhang Hua Wang Zhongcheng Zhou Lingyi Chen Jun Zhou Lin Liu 2017Protein & Cell2017,8,5:1
18An analytical solution for one-dimensional contaminant diffusion through multi-layered system and its applications显示文摘Yunmin Chen Haijian Xie Han Ke Renpeng Chen 2009Environmental Geology2009,,5:1
19A Theoretical Solution for Pilesupported 显示文摘Chen Renpeng Chen Yunmin Xu Zhengzhong 2008Candian Geotechnical Journal2008,,45:1
20Correlation of Shear Wave Velocity with Liquefaction Resistance Based on Laboratory Tests 显示文摘CHEN Yunmin KE Han CHEN Renpeng 2005Soil Dynamics and Earthquake Engineering2005,25,6:1
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