检索结果-南通市图书馆

UWB-over-Fiber transmission system using a dual-output Mach-Zehnder modulator

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Optics Letters 2010年第5期8卷 454-456页

作者：赵颖郑小平张汉一周炳琨 state key laboratory on Integrated Optics Tsinghua National Laboratory for Information Science and TechnologyDepartment of Electronic EngineeringTsinghua University

A novel scheme for ultra-wideband（UWB） monocycle pulse generation is proposed based on a dual-output push-pull Mach-Zehnder modulator（MZM）.The MZM is driven by a non-return-to-zero（NRZ） data sequence and biased at the nonlinear point to generate edge-triggered *** combine the complementary pulses forming a monocycle UWB pulse,two schemes are used to implement incoherent summation structure. A proof-of-concept experiment of UWB-over-fiber down-link system is set ***,by using digital signal processing（DSP） to calculate the bit error rate（BER）,the transmission performance of two system configurations is studied.

关键词： Bit error rate Light modulators Optical communication Signal processing

Preparation of microstructure-controllable superhydrophobic polytetrafluoroethylene porous thin film by vacuum thermal-evaporation

在线全文

学校读者我要写书评

暂无评论

Frontiers of Materials Science 2016年第3期10卷 320-327页

作者： Na YI Shanhu BAO Huaijuan ZHOU Yunchuan XIN Aibin HUANG Yining MA Rong LI PingJIN state key laboratory of High Performance ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Beijing 100049 China Materials Research Institute for Sustainable Development National Institute of Advanced Industrial Science and Technology (AIST) Nagoya 463-8560 Japan

The three-dimensional porous network polytetrafluoroethylene （PTFE） thin films were achieved by a vacuum technique through evaporating the pure PTFE powders. The surfaces of PTFE thin films showed various morphologies by adjusting the evaporation temperature and the corresponding contact angle ranging from 133° to 155°. Further analyses of surface chemical composition and morphology by FTIR and FE-SEM revealed that the origin of hydrophobicity for the PTFE thin films could be ascribed to the fluorine-containing groups and the surface morphologies, indicating that abundant -CF2 groups and network structures with appropriate pore sizes played a vital role in superhydrophobicity. By characterization of UV-Vis, the films also showed high transmittance and antireflection effect. The films prepared by this simple method have potential applications such as waterproof membrane and self-cleaning coating.

关键词： polytetrafluoroethylene (PTFE) vacuum superhydrophobicity

Controlled high-density interface engineering of Fe_(3)O_(4)-FeS nanoarray for efficient hydrogen evolution

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2022年第5期31卷 96-103页

作者： Min Yang Wen-Hui Hu Meng-Xuan Li Yu-Ning Cao Bin Dong Yu Ma Hui-Ying Zhao Feng-Ge Wang Jier Huang Yong-Ming Chai state key laboratory of Heavy Oil processing College of Chemical EngineeringChina University of Petroleum(East China)Qingdao 266580ShandongChina Department of Chemistry Marquette UniversityMilwaukeeWI 53201United States X-ray Science Division Argonne National LaboratoryArgonneIL 60349United States

The rational design of double active sites system is vital for constructing high-efficiency iron sulfides electrocatalysts towards hydrogen evolution reaction(HER) in alkaline media. However, it remains a challenge to controllably create the high-density interface of double sites for optimal synergistic ***, we reported a simple chemical oxidation-induced surface reconfiguration strategy to obtain the interface-rich Fe_(3)O_(4)-FeS nanoarray supported on iron foam(Fe_(3)O_(4)-FeS/IF) using FeS nanosheets as precursors. The abundant Fe_(3)O_(4)-FeS interfaces could improve the dispersion of active sites and facilitate the electron transfer, leading to enhanced hydrogen evolution efficiency. And meanwhile, by altering the oxidation temperature, the content of S and O could be effectively controlled, further achieving the ratio optimization of Fe_(3)O_(4)to FeS. Synchrotron-based X-ray absorption near-edge structure, X-ray photoelectron spectroscopy and ultraviolet photoemission spectroscopy consistently confirm the changes of electronic structure and d-band center of Fe_(3)O_(4)-FeS after chemical oxidation. Consequently, Fe_(3)O_(4)-FeS/IF exhibits excellent alkaline HER activity with a low overpotential of 120.8 mV to reach 20 mA cm^(-2),and remains stable ranging from 10, 20 to 50 mA cm^(-2) for each 20 h, respectively. Therefore, the facile and controllable chemical oxidation may be an effective strategy for designing high-density interfaces of transition metal-based sulfides towards alkaline HER.

关键词： High-density interfaces Double sites Chemical oxidation Hydrogen evolution reaction

Interfacial characteristics and mechanical properties of additive manufacturing martensite stainless steel on the Cu-Cr alloy substrate by directed energy deposition

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第31期90卷 121-132页

作者： Wenqi Zhang Hailong Liao Zhiheng Hu Shasha Zhang Baijin Chen Huanqing Yang Yun Wang Haihong Zhu Wuhan National laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China state key laboratory of Material processing and Die&Mould Technology School of Material Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China XI’AN Space Engine Company Limited Xi’an710100China

Copper/steel is a typical bimetal functional material,combining the excellent electrical and thermal conductivity of copper alloy and the high strength and hardness of stainless *** has been recent interest in manufacturing copper/steel bimetal by directed energy deposition(DED)due to its layer-bylayer ***,cracks tend to form on the copper/steel interface because of the great difference in thermal expansion coefficient and crystal structure between copper and *** this work,interfacial characteristics and mechanical properties of the copper/steel bimetal were studied from one layer to *** laser power has a great influence on the Cu element distribution of the molten pool,affecting the crack formation dramatically on the solidification *** tend to form along columnar grain boundaries because of the Cu-rich liquid films and spherical particles in the ***-free and good metallurgical bonding copper/steel interface is formed at a scanning velocity of 800 mm/min and the laser power of 3000 *** ultimate tensile strength(UTS)and the break elongation(EL)of the vertically combined crack-free copper/steel bimetal are 238.2±4.4 MPa and 20.6±0.7%,*** fracture occurs on the copper side instead of the copper/steel interface,indicating that the bonding strength is higher than that of the Cu-Cr *** UTS of the horizontally combined crack-free copper/steel bimetal is 746.7±22.6 MPa,which is 200%higher than that of the Cu-Cr alloy *** microhardness is 398.6±5.4 HV at the steel side and is 235.3±64.1 HV at the interface,which is400%higher than that of the Cu-Cr alloy *** paper advances the understanding of the interfacial characteristics of heterogeneous materials and provides guidance and reference for the fabrication of multi-material components by DED.

关键词： Directed energy deposition Additive manufacturing Bimetal Interfacial characteristics Crack

Encapsulation strategies on 2D materials for field effect transistors and photodetectors

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第5期33卷 2281-2290页

作者： Wenjuan Huang Yue Zhang Mengting Song Bugao Wang Huayi Hou Xiaozong Hu Xiangbai Chen Tianyou Zhai Hubei key laboratory of Optical Information and Pattern Recognition Wuhan Institute of TechnologyWuhan 430205China state key laboratory of Materials processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Green Catalysis Center College of ChemistryZhengzhou UniversityZhengzhou 450001China

Two-dimensional(2D)layered materials provide a promising alternative solution for overcoming the scal-ing limits in conventional Si-based ***,practical applications of 2D materials are facing crucial bottlenecks,particularly that arising from the instability under ambient *** studies of degradation mechanisms and protecting strategies for overcoming the ambient instability of 2D materials have attracted extensive research attentions,both experimentally and *** review attempts to provide an overview on the recent progress of the encapsulation strategies for 2D *** en-capsulation strategies of mechanical transfer,polymer capping,atomic layer deposition,in-situ oxidation,and surface functionalization are systematically discussed for improving the ambient stability of 2D *** addition,the current advances in air-stable and high-performance 2D materials-based field effect transistors(FETs)and photodetectors assisted by the encapsulation strategies are ***,the future directions of encapsulation techniques of 2D materials for FETs and photodetectors applications are suggested.

关键词： Two-dimensional materials Encapsulation Degradation Stability Field effect transistors Photodetectors

Ni(OH)_(2) Derived from NiS_(2) Induced by Reflux Playing Three Roles for Hydrogen/Oxygen Evolution Reaction

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2022年第8期41卷 52-57页

作者： Sheng-Jun Xu Ya-Nan Zhou Guo-Ping Shen Bin Dong Dongying Haike Ruilin Chemical Co. LTD.Dongying 257000China state key laboratory of Heavy Oil processing College of Chemistry and Chemical EngineeringChina University of Petroleum(East China)Qingdao 266580China

Developing efficient and promising non-noble catalysts for oxygen evolution reaction(OER) and hydrogen evolution reaction(HER) is vital but still a huge challenge for the clean energy system. Herein, we have integrated the active components for OER(Ni(OH)_(2)) and HER(Ni S_(2) and Ni(OH)_(2)) into Ni(OH)_(2)@NiS_(2) heterostructures by a facile reflux method. The in-situ formed Ni(OH)_(2) thin layer is coated on the surface of hollow Ni S2 nanosphere. The uniform Ni(OH)_(2)@NiS_(2) hollow sphere processes enlarge the electrochemically active specific surface area and enhance the intrinsic activity compared to NiS_(2) precursor, which affords a current density of 10 m A cm^(-2) at the overpotential of 309 m V and 100 m Acm^(-2) at 359 m V for OER. Meanwhile, Ni(OH)_(2)@NiS_(2) can reach 10 m A cm^(-2) at 233 m V for HER, superior to pure NiS_(2). The enhanced performance can be attributed to the synergy between Ni(OH)_(2) and NiS_(2). Specifically, Ni(OH)_(2) has three functions for water splitting: providing active sites for hydrogen adsorption and hydroxyl group desorption and working as real OER active sites. Moreover, Ni(OH)_(2)@NiS_(2) displays great stability for OER(50 h) and HER(30 h).

关键词： Ni(OH)_(2) NiS_(2) heterostructures oxygen evolution reaction hydrogen evolution reaction

Multi-scale simulation of single crystal hollow turbine blade manufactured by liquid metal cooling process

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2018年第1期28卷 78-84页

作者： Xuewei Yan Hang Zhang Ning Tang Changbo Sun Qingyan Xu Baicheng Liu key laboratory for Advanced Materials processing Technology MoE School of Materials Science and Engineering Tsinghua University School of Mechanical Engineering Xi’an Jiao Tong University State Key Laboratory of Manufacturing System Engineering SUVAST Special Alloy Technology Co. LTD 4. Shenyang Aero Engine Precision Casting Co. LTD

Liquid metal cooling(LMC) process as a powerful directional solidification(DS) technique is prospectively used to manufacture single crystal(SC) turbine blades. An understanding of the temperature distribution and microstructure evolution in LMC process is required in order to improve the properties of the blades. For this reason, a multi-scale model coupling with the temperature field, grain growth and solute diffusion was established. The temperature distribution and mushy zone evolution of the hollow blade was simulated and *** to the simulation results, the mushy zone might be convex and ahead of the ceramic beads at a lower withdrawal rate, while it will be concave and laggard at a higher withdrawal rate, and a uniform and horizontal mushy zone will be formed at a medium withdrawal rate. Grain growth of the blade at different withdrawal rates was also investigated. Single crystal structures were all selected out at three different withdrawal ***, mis-orientation of the grains at 8 mm/min reached ～30°, while it was ～5° and ～15° at 10 mm/min and 12 mm/min, respectively. The model for predicting dendritic morphology was verified by corresponding experiment. Large scale for 2D dendritic distribution in the whole sections was investigated by experiment and simulation, and they presented a well agreement with each other.

关键词： Hollow blade Single crystal Multi-scale simulation Liquid metal cooling

Dialectics of nature： Temporal and spatial regulation in material sciences

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2017年第4期10卷 1115-1124页

作者： Jianlong Xia Lei Jiang School of Chemistry Chemical Engineering and Life Science State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology No. 122 Luoshi Road Wuhan 430070 China laboratory of Bioinspired Smart Interfacial Science Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China

The cooperative interaction distance measure has been proposed as a novel law pertaining to dialectics of nature, and has been extensively carried out in the design of functional nanomaterials. However, the temporal and spatial dimensions are akin to yin and yang, and thus temporal regulation needs to be accounted for when implementing the above-mentioned principle. Here, we summarize recent advances in temporally and spatially regulated materials and devices. We showcase the temporal regulation of organic semiconductors for organic photovoltaics （OPVs） using the example of exciton lifetime manipulation. As an example of spatial regulation, we consider the distribution of charge carriers in core-shell quantum dot （QD） nanocrystals for modulating their optical properties. Long exciton lifetime can in principle increase the exciton diffussion length, which is desiable for high-efficiency large-area OPV devices. Spatially regulated QDs are highly valuable emitters for light-emitting applications. We aim to show that cooperative spatio-temporal regulation of nanomaterils is of vital importance to the development of functional devices.

关键词： dialectics of nature temporal regulation spatial regulation singlet fission

Protein adsorption on materials surfaces with nano-topography

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2007年第23期52卷 3169-3173页

作者： SONG Wei CHEN Hong School of Materials Science and Engineering Wuhan University of Technology Wuhan 430070 China state key laboratory of Advanced Technology for Materials Synthesis and processing Wuhan University of Technology Wuhan 430070 China

Protein adsorption behavior on the surfaces of biomedical materials is highly related to the biocom- patibility of the materials. In the past, numerous research reports were mainly focused on the effect of chemical components of a material’s surface on protein adsorption. The effect of surface topography on protein adsorption, the topic of this review, has recently received keen interest. The influence of surface nano-topographic factors, including roughness, curvature and geometry, on protein adsorption as well as the protein adsorption behavior, such as the amount of protein adsorbed, the activity and morphology of adsorbed protein, is introduced.

关键词：蛋白质吸附材料表面地形图生物适应性