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Search Results: 1 - 10 of 104278 matches for " Yingkui Zhang "
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Comparisons between Chinese and Mongolian Patient Satisfaction  [PDF]
Na Chen, Xinxing Zhou, Yingkui Zhang
Psychology (PSYCH) , 2017, DOI: 10.4236/psych.2017.813135
Abstract: This study compared the differences between Chinese and Mongolian patient satisfaction and investigated factors influencing patient satisfaction of the two countries in order to provide suggestions for the establishment and improvement of Mongolia’s health care system. This study involved two questionnaire surveys. Questionnaire Survey I investigated patient satisfaction of the two countries, whereas based on the first survey, Questionnaire Survey II revisited the respondents and investigated the reasons for their dissatisfaction with different aspects of health care service. According to the results of Questionnaire Survey I, Chinese overall patient satisfaction was higher than that of Mongolian. China and Mongolia had their own advantages in different health care service aspects respectively. The factors of consideration, cost of care and quality/competence showed significant influences on Chinese patient satisfaction, whereas the factors of hospitals, payment mechanisms and quality/competence showed significant influences on Mongolian patient satisfaction. According to the results of Questionnaire Survey II, Chinese individuals were more likely to express their dissatisfaction. Chinese individuals’ dissatisfaction focused on the issues of high costs of seeing a doctor, long waiting time and unreasonable procedures, whereas Mongolian individuals’ dissatisfaction focused on the issues of long waiting time, high costs of seeing a doctor and doctors’ poor attitudes. Implications were discussed for the development of Mongolia’s health care system.
Synthesis and photo-responsive behaviors of hollow polyazobenzene micro-spheres
XiaoTao Wang,YingKui Yang,ZhiFang Yang,YongGui Liao,Wei Zhang,XiaoLin Xie
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-010-3248-6
Abstract: By means of distillation precipitation polymerization, the silica-hybrid particles with polyazobenzene shell (PAzo@SiO2) microspheres were prepared with 6-(4-methoxy-4′-oxy-azobenzene) hexyl methacrylate (Azo-M) as monomer, divinylbenzene (DVB) as cross-linker, and ~250 nm vinylated sol-gel silica particles as template. Hollow polyazobenzene microspheres were further developed after selective removal of the silica cores with HF solution. When the content of DVB related to Azo-M is 20 wt%, the acetonitrile is 200 mL, and the polymerization time is 4.5 h, the hollow PAzo microspheres with about 20 nm shell are successfully fabricated. These hollow PAzo microspheres have excellent reversible photoisomerization, and their first-order rate constant of trans-cis isomerization only decreases 11.8% compared with homopolymer of azobenzene (Homo-PAzo).
0.25μm Gate-Length AlGaN/GaN Power HEMTs on Sapphire with fT of 77GHz
Zheng Yingkui,Liu Guoguo,He Zhijing,Liu Xinyu,Wu Dexin
半导体学报 , 2006,
Abstract: 在蓝宝石衬底上用MOCVD技术生长的AlGaN/GaN结构上制作出0.25μm栅长的高电子迁移率功率晶体管. 0.25μm栅长的单指器件测到峰值跨导为250mS/mm,特征频率为77GHz. 功率器件的最大电流密度达到1.07A/mm. 8GHz频率下在片测试80×10μm栅宽器件的输出功率为27.04dBm,同时功率附加效率达到26.5%.
Progress in Imidazolium Ionic Liquids Assisted Fabrication of Carbon Nanotube and Graphene Polymer Composites
Rengui Peng,Yuanzhen Wang,Wei Tang,Yingkui Yang,Xiaolin Xie
Polymers , 2013, DOI: 10.3390/polym5020847
Abstract: Carbon nanotubes (CNTs) and graphene sheets are the most promising fillers for polymer nanocomposites due to their superior mechanical, electrical, thermal optical and gas barrier properties, as well as high flame-retardant efficiency. The critical challenge, however, is how to uniformly disperse them into the polymer matrix to achieve a strong interface for good load transfer between the two. This problem is not new but more acute in CNTs and graphene, both because they are intrinsically insoluble and tend to aggregate into bundles and because their surfaces are atomically smooth. Over the past decade, imidazolium ionic liquids (Imi-ILs) have played a multifunctional role (e.g., as solvents, dispersants, stabilizers, compatibilizers, modifiers and additives) in the fabrication of polymer composites containing CNTs or graphene. In this review, we first summarize the liquid-phase exfoliation, stabilization, dispersion of CNTs and graphene in Imi-ILs, as well as the chemical and/or thermal reduction of graphene oxide to graphene with the aid of Imi-ILs. We then present a full survey of the literature on the Imi-ILs assisted fabrication of CNTs and graphene-based nanocomposites with a variety of polymers, including fluoropolymers, hydrocarbon polymers, polyacrylates, cellulose and polymeric ionic liquids. Finally, we give a future outlook in hopes of facilitating progress in this emerging area.
Microstructure and Performance of 2Y-PSZ/TRIP Steel Composites
Microstructure and Performance of 2Y-PSZ/TRIP Steel Composites

Yingkui GUO,Yu ZHOU,Dongbo LI,Xiaoming DUAN,Tingquan LEI,

材料科学技术学报 , 2003,
Abstract: 2Y-PSZ/TRIP steel composites have been sintered by hot-pressing method. Their microstructure and mechanical properties were investigated by means of SEM, TEM, XRD and static tension, split Hopkinson pressure bar method. The results showed that the strength and elastic modulus of 2Y-PSZ/TRIP steel composites at room temperature decreased with the increase of 2Y-PSZ content. The main reason was that the combining strength was quite weak between the grains of ZrO2. Distortion induced martensite transformation and plasticity during the dynamic loading increased the strength and distortion capability of the composites. The transformation was carried out mainly through twins formation. The shape of martensite induced by distortion was lamellate with substructures of twins. The habit plane was near {259}T with no mid-ridge and no explosion phenomena. The interface was straight between the austenite and martensite induced by distortion. The increase of 2Y-PSZ content, on the one hand, made the composite dynamic flow stress improved. Thereby, the fracture strength was improved. On the other hand, it depressed both the distortion capability and the martensite transformation induced by distortion. This resulted in the decrease of dynamic fracture strength.
A revised approach to Schottky parameter extraction for GaN HEMT
用于GaN HEMT肖特基参数提取的修正方法

Wang Xinhu,Zhao Miao,Liu Xinyu,Zheng Yingkui,Wei Ke,

半导体学报 , 2010,
Abstract: We carry out a thermal storage research on GaN HEMT at 350 oC for 48 h, and a recess phenomenon is observed in the low voltage section of Schottky forward characteristics. The decrease of 2DEG density will be responsible for the recess phenomenon. Because the conventional method is not suitable for this kind of curve, a revised approach is presented by analyzing the back-to-back Schottky junction energy band to extract Schottky parameters, which leads to a consistent fit effect.
Device Characteristics Comparison Between GaAs Single and Double Delta-Doped Pseudomorphic High Electron Mobility Transistors

Chen Zhen,Zheng Yingkui,Liu Xinyu,He Zhijing,Wu Dexin,

半导体学报 , 2004,
Abstract: The Al 0.24Ga 0.76As/In 0.22Ga 0.78As single delta-doped PHEMT (SH-PHEMT) and double delta-doped PHEMT (DH-PHEMT) are fabricated and investigated.Based on the employment of double heterojunction,double delta doped design,the DH-PHEMT can enhance the carrier confinement,increase the electron gas density,and improve the electron gas distribution,which is beneficial to the device performance.A high device linearity,high transconductance over a large gate voltage swing,high current drivability are found in DH-PHEMT.These improvements suggest that DH-PHEMT is more suitable for high linearity applications in microwave power device.
X-Band GaN Power HEMTs with Power Density of 2.23W/mm Grown on Sapphire by MOCVD
Wang Xiaoliang,Liu Xinyu,Hu Guoxin,Wang Junxi,Ma Zhiyong,Wang Cuimei,Li Jianping,Ran Junxue,Zheng Yingkui,Qian He,Zeng Yiping,Li Jinmin,
Wang Xiaoliang
,Liu Xinyu,Hu Guoxin,Wang Junxi,Ma Zhiyong,Wang Cuimei,Li Jianping,Ran Junxue,Zheng Yingkui,Qian He,Zeng Y

半导体学报 , 2005,
Abstract: The growth,fabrication,and characterization of 0.2μm gate-length AlGaN/GaN HEMTs, with a high mobility GaN thin layer as a channel,grown on (0001) sapphire substrates by MOCVD,are described.The unintentionally doped 2.5μm thick GaN epilayers grown with the same conditions as the GaN channel have a room temperature electron mobility of 741cm2/(V·s) at an electron concentration of 1.52e16cm-3.The resistivity of the thick GaN buffer layer is greater than 1e8Ω·cm at room temperature.The 50mm HEMT wafers grown on sapphire substrates show an average sheet resistance of 440.9Ω/□ with uniformity better than 96%.Devices of 0.2μm×40μm gate periphery exhibit a maximum extrinsic transconductance of 250mS/mm and a current gain cutoff frequency of 77GHz.The AlGaN/GaN HEMTs with 0.8mm gate width display a total output power of 1.78W (2.23W/mm) and a linear gain of 13.3dB at 8GHz.The power devices also show a saturated current density as high as 1.07A/mm at a gate bias of 0.5V.
Impact of UV/ozone surface treatment on AlGaN/GaN HEMTs
UV/Ozone 表面处理对AlGaN/GaN HEMTs 性能的影响

Yuan Tingting,Liu Xinyu,Zheng Yingkui,Li Chengzhan,Wei Ke,Liu Guoguo,

半导体学报 , 2009,
Abstract: Surface treatment plays an important role in the process of making high performance AlGaN/GaN HEMTs. A clean surface is critical for enhancing device performance and long-term reliability. By experimenting with different surface treatment methods, we find that using UV/ozone treatment significantly influences the electrical properties of Ohmic contacts and Schottky contacts. According to these experimental phenomena and X-ray photoelectron spectroscopy surface analysis results, the effect of the UV/ozone treatment and the reason that it influences the Ohmic/Schottky contact characteristics of AlGaN/GaN HEMTs is investigated.
An 8W X Band AlGaN/GaN Power HEMT
8W AlGaN/GaN HEMT功率器件的研制

Liu Guoguo,Zheng Yingkui,Wei Ke,Li Chengzhan,Liu Xinyu,He Zhijing,

半导体学报 , 2008,
Abstract: 报道了基于国产衬底以及国产外延的AlGaN/GaN HEMT X波段功率器件的研究进展.利用国产衬底以及外延材料,优化了器件栅场板的结构,研制成功栅长0.35μm,栅宽为lmm的微波功率器件.该器件输出电流密度达到0.83A/mm,击穿电压大于100V,跨导为236mS/mm,截止频率(fT)达到30GHz,最大振荡频率(fmax)为32GHz,8GHz下在片进行连续波测试,漏端电压为40V时测试得到功率增益4.9dB,输出功率达8W,功率附加效率(PAE)为45%.
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