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1,121 results on '"Zhang, Hongfei"'

259. Crystal structure of bis(μ2-2-oxido-2-phenylacetate-κ3 O:O,O′)-bis(1-isopropoxy-2-oxo-2-phenylethan-1-olato-κ2O,O′)-bis(propan-2-olato-κ1O)dititanium(IV), C44H52O14Ti2

Author

Niu Yongsheng, Guo Yuhua, Zhang Hongfei, Liu Nana, and Yu Youzhu

Subjects
Inorganic Chemistry, Phenylacetate, 010405 organic chemistry, Chemistry, General Materials Science, Crystal structure, 010402 general chemistry, Condensed Matter Physics, 01 natural sciences, Medicinal chemistry, 0104 chemical sciences
Abstract

C44H52O14Ti2, orthorhombic, Pbca (no. 61), a = 15.0005(7) Å, b = 15.9478(8) Å, c = 18.4438(10) Å, V = 4412.2(4) Å3, Z = 4, R gt(F) = 0.0372, wR ref(F 2) = 0.1089, T = 296(2) K.

Published
2021

269. Wind erosion and its ecological effects on soil in the northern piedmont of the Yinshan Mountains

Author

Jiaqi Fan, Yunfeng Yao, Yan Xudong, Wenfeng Chi, Lin Sun, Wu Xiaoguang, Yushan Jia, Zhang Hongfei, Yan Xu, and Jian Zhou

Subjects
0106 biological sciences, General Decision Sciences, 010501 environmental sciences, 010603 evolutionary biology, 01 natural sciences, Wind speed, Northern piedmont of the Yinshan Mountains, Restoration ecology, Ecology, Evolution, Behavior and Systematics, QH540-549.5, 0105 earth and related environmental sciences, RWEQ model, Ecology, business.industry, Storm, Wind direction, Soil quality, Arid, Wind erosion of soil, Agriculture, Influencing factor, Aeolian processes, Environmental science, business, Ecological effect
Abstract

Soil erosion by wind is a serious problem that threatens ecological security and damages the ecological environment, thereby hindering the sustainable development of agriculture and animal husbandry in arid and semiarid areas. Using the northern piedmont of the Yinshan Mountains in the Inner Mongolia Autonomous Region of China as a study area, this study explores the spatiotemporal variation in soil loss by wind erosion and its impact on soil nutrients from 1990 to 2015. Various approaches, including remote sensing technology, the revised wind erosion equation model, the fallout cesium-137 tracing technique, and the geographic information system (GIS) spatial analysis technique, were jointly used in the present study. From 1990 to 2015, the soil loss by wind erosion obviously decreased, with a slope of −0.59 t/ha/a, in the study area. Affected by factors such as regional topography and wind direction, the wind erosion modulus is high in the northwest and low in the south and southeast of the northern piedmont of the Yinshan Mountains. The soil nutrient content decreased overall from 1990 to 2015, including a severe loss from 1990 to 2005 and a relatively low nutrient enrichment from 2005 to 2015. The decline in the sand-dust storm frequency and wind speed protected the soil from wind erosion. Implementing ecological management projects has played an important role in slowing wind erosion and enhancing the regional ability to resist wind erosion and fix sand. To improve soil quality and the regional ecological environment, ecological restoration projects should be further promoted in the study area.

Published
2021

270. Baseline quantitative hepatitis B core antibody titre alone strongly predicts HBeAg seroconversion across chronic hepatitis B patients treated with peginterferon or nucleos(t)ide analogues

Author

Fan, Rong, Sun, Jian, Yuan, Quan, Xie, Qing, Bai, Xuefan, Ning, Qin, Cheng, Jun, Yu, Yanyan, Niu, Junqi, Shi, Guangfeng, Wang, Hao, Tan, Deming, Wan, Mobin, Chen, Shijun, Xu, Min, Chen, Xinyue, Tang, Hong, Sheng, Jifang, Lu, Fengmin, Jia, Jidong, Zhuang, Hui, Xia, Ningshao, Hou, Jinlin, Dou, Xiaoguang, Shi, Junping, Ren, Hong, Wang, Maorong, Ma, Hong, Gao, Zhiliang, Zhang, Hongfei, and Chen, Chengwei

Published
2016
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271. Experimental study on the pressure drop characteristics of supercritical CO2 in horizontal rectangular microchannels.

Author

Zhang, Hongfei, Shi, Lingfeng, Wang, Xuan, Sun, Rui, Yuan, Ping, Tian, Hua, and Shu, Gequn

Subjects
*PRESSURE drop (Fluid dynamics), *HEAT exchangers, *SUPERCRITICAL carbon dioxide, *SUPERCRITICAL water, *HEAT flux, *PRINTED circuits, *THERMOPHYSICAL properties
Abstract

The pressure drop characteristics of supercritical carbon dioxide (S-CO2) are experimentally studied in horizontal rectangular microchannels with hydraulic diameters of 1 and 2 mm, which are used in printed circuit heat exchangers. The operating conditions include an operating pressure of 9–12 MPa, a mass flux of 290–1200 kg/m2 s, and a heat flux of 25–50 kW/m2. The four contributors to pressure drop in the S-CO2 microchannels were investigated. The results indicate that the total pressure drop decreases for lower operating pressures and mass fluxes, whereas the heat flux has little impact. The most significant contributor to the total pressure drop is the frictional pressure drop. The accelerational pressure drop increases with the heat flux. Eventually, a new frictional resistance correlation is proposed where the microchannel size and thermophysical property variations are considered. [ABSTRACT FROM AUTHOR]

Published
2022
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282. High-Precision Flatness Measurement for Cryogenic Mosaic Focal Plane Arrays

Author

Zhang, Yihao, Zhang, Hongfei, Zhang, Jun, Wang, Xingbo, and Wang, Jian

Abstract

Mosaic charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) cameras are crucial for giant telescopes, especially those with a large field of view (FOV). One of the critical determinants of image quality is the flatness of the mosaic focal plane arrays (MFPAs). The MFPAs can only be assembled at room temperature and operated under cryogenic cooling with a vacuum chamber to reduce image noise; however, changes and inhomogeneities in temperature can deform the focal plane and affect the flatness. Under cryogenic conditions, the measurement must be taken through a flat dewar window, which will reduce the measurement precision. To correctly measure the MFPAs under cryogenic conditions, we developed a method called differential triangulation measurement (DTM) using the method of laser triangulation and differential measurement. In this study, the feasibility of the laser triangulation measurement through a flat window using the oblique mode is demonstrated. Furthermore, a differential measurement method using two laser triangulation sensors is adopted to improve the precision of measurement. One sensor is used to scan a precision optical flat as a reference, and the other is used to scan the MFPAs. A flatness calculation method based on the progressive sample consensus algorithm (PROSAC) is used to optimize data processing. A measurement system based on DTM (DTMS) is designed and implemented for the flatness measurement of MFPAs in a vacuum chamber. The measurement precision of the system was verified by measuring an ultrahigh precision gauge step block. The test results show that the measurement error through the flat dewar window is less than 0.5%. Finally, the DTMS is applied in the MFPA flatness measurement of the prime-focus camera of the wide field sky survey telescope (WFST).

Published
2023
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283. Ultra-fast terahertz time domain spectroscopy system

Author

Zhang Hongfei, Zhang Cun-Lin, He Jingsuo, and Su Bo

Subjects
Physics, Dynamic range, Terahertz radiation, business.industry, Detector, Laser, Signal, Atomic and Molecular Physics, and Optics, law.invention, Pulse (physics), Optics, law, Femtosecond, business, Terahertz time-domain spectroscopy
Abstract

Ultra-fast terahertz time-domain spectroscopy(THz-TDS) system operates based on the principle of high-speed asynchronous optical sampling. The system uses two femtosecond oscillators whose repetition frequencies can vary around 1 GHz, and uses a high-bandwidth feedback circuit to control the repetition frequencies. There is a difference of Δf in the repetition frequency between two femtosecond oscillators. One femtosecond oscillator has a repetition frequency of 1G+Δf Hz, which is the pump pulse; the other has a repetition frequency of 1G Hz, which provides the time difference between the pump pulse and the probe pulse, and the time delay varies periodically with the scanning cycle. The period can be given by 1/Δf. This system abandons the mechanical delay line necessary for the traditional THz-TDS system and uses double-photon detector to generate trigger signal. When the frequency difference between the two femtosecond laser oscillators is 1 kHz, a THz spectrum can be detected in only 1 ms, and a THz signal with a dynamic range of 21 dB and a spectral resolution of 5 GHz can be obtained in 10.3 s. Hence it can be characterized by fast detection speed and high resolution. It has incomparable advantages over the traditional THz-TDS system in the application environment that requires rapid measurement.

Published
2019

290. Parathyroid Hormone (1–34) Attenuates Cartilage Degradation and Preserves Subchondral Bone Micro-architecture in Rats with Patella Baja-Induced-Patellofemoral Joint Osteoarthritis.

Author

Zhang, Hongfei, Bei, Mingjian, Zheng, Zhiyuan, Liu, Ning, Cao, Xuehui, Xiao, Yaping, Lian, Qiangqiang, Wang, Yudan, Hou, Xiaoli, and Tian, Faming

Subjects
*PATELLAR tendon, *PATELLOFEMORAL joint, *CARTILAGE, *PATELLA, *PARATHYROID hormone, *BONE health, *CARTILAGE cells, *OSTEOARTHRITIS
Abstract

Several studies have revealed that PTH1-34 may possess the potential for treating osteoarthritis (OA) and osteoporosis. However, no study has yet determined whether PTH1-34 can be used for the treatment of patella baja-induced patellofemoral joint OA (PFJOA). Thus, this study sought to assess the efficacy of PTH1-34 for the treatment of PFJOA in a rat model. Patella baja was induced in 3-month-old female Sprague–Dawley (SD) rats by patellar ligament shortening (PLS), after which the rats were randomly divided into three groups (n = 12): Sham, PLS, and PTH group (PTH + PLS, PTH1-34, 30 µg/kg/d, 5 days per week for 10 weeks). Thereafter, radiographic imaging, macroscopic and microscopic analyses, immunohistochemistry, and microcomputed tomography (CT) analysis were performed. The appearance of PLS-induced PFJOA promoted obvious changes in the patellar position and structure in the PLS group, which were characterized by cartilage degeneration, subchondral bone microstructure deterioration, patella baja, and increasing patella length. However, these negative characteristics were markedly ameliorated by PTH1-34, which not only inhibited cartilage catabolism by decreasing MMP-13 and ADAMTS-4 but also enhanced anabolism by increasing Col-II and Aggrecan. Furthermore, the micro-CT results showed a marked improvement in subchondral bone microarchitecture. The findings presented herein demonstrated that early treatment with PTH1-34 could improve cartilage metabolism and subchondral bone health in this PFJOA model. [ABSTRACT FROM AUTHOR]

Published
2022
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