218 research outputs found

    Molecular Dynamics Studies on 3D Structures of the Hydrophobic Region PrP(109-136)

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    Prion diseases caused by the conversion from a soluble normal cellular prion protein into insoluble abnormally folded infectious prions, are invariably fatal and highly infectious degenerative diseases that affect a wide variety of mammalian species. The palindrome and the Glycine-rich conserved segment in the hydrophobic region 109-136 control the conversion from normal prion protein to form into diseased prions. This paper gives detailed reviews on the 109-136 region and presents the studies of its 3D structures and structural dynamics.Comment: This paper was accepted on 18-02-2013 by the journal Acta Biochimica et Biophysica Sinica, in press in Vol 45 No 4, Apr 201

    The Factors Influencing Teachers' Willingness to Remain in Rural Areas After the Expiration of Their Compulsory Service Contract: A Case Study in Enshi Prefecture, Hubei Province, China

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    Quality education can only be achieved with the assistance of experienced and qualified teachers. In order to ensure quality education in disadvantaged areas in China, it is necessary to keep experienced teachers in rural areas. This paper investigates factors that could influence rural teachers’ decision to stay or not on teaching at the expiry of their service contract. As a part of project, “Research on rural Teacher Training Mode in Minority Areas of Hubei Province in post-poverty Era “data from 1193 rural teachers who had qualified from a government teacher training programme from selected villages under the jurisdiction of the Enshi Prefecture, Hubei province was collected. As part of the survey, a number of factors are examined that influence a teacher's willingness to stay or leave, as well as remedial measures that are deemed necessary to prevent teachers from leaving. For the analysis of the data, SPSS 25 and AMOS 24 were used. The study found that the teachers have a high willingness to stay on the job after the contract expires. Among the factors contributing to their willingness are the local cultural environment, the local infrastructure attachment to the area, and the school's working environment. Wage income, professional identity, professional development, and school working conditions also play an important role as maintenance factors. There is a direct relationship between the rural infrastructure and a person's willingness to continue working after the expiration of a contract, and there is also direct relationship between the local attachment and the cultural atmosphere of the local community. Local attachment is the dominant factor, the local infrastructure is a secondary improvement area, and salary, promotion of opportunities, respect for teachers and education are in the priority improvement area. Finally, the paper proposes that the retention of rural teachers should be based on the cultivation of local attachment, rural revitalization, improvement of health factors and construction of “UGSR–P” cultivation of community

    Experimental Study on Physical Simulation of Large-Scale Interfracture Injection and Production with Different Injection Media in Tight Oil Reservoirs

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    AbstractGiven the difficulty of water injection and effective displacement system establishment in Changqing oilfield, this research carried out the interfracture injection and production experiment of a large outcrop model with two types of injection fluid medium, natural gas and surfactant, and studied the interfracture injection and production law of different displacing medium and the principal contradiction existing in the different displacing medium. The results show that natural gas drive in tight oil reservoir is beneficial to reduce the Jamin resistance and form a rapid oil production. Still, the gas drive process is easy to develop gas breakthrough, leading to a decrease in gas utilization ratio, and its oil displacement efficiency is 17.25%. Additionally, due to the strong adsorption of surfactant, the seepage capacity of a porous medium in the process of surfactant-oil displacement is reduced, and blockage is formed at the injection end, resulting in the poor oil displacement effect of surfactant. However, compared with natural gas injection, the surfactant has higher oil displacement efficiency, up to 22.05%. Therefore, for tight oil reservoirs, rational utilization of the advantages of different mediums and controlling their disadvantages are essential for the development of such reservoirs

    Direct Bypass Surgery Vs. Combined Bypass Surgery for Hemorrhagic Moyamoya Disease: A Comparison of Angiographic Outcomes

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    Objective: Extracranial-intracranial bypass is currently recognized as the optimal treatment for hemorrhagic-type moyamoya disease (MMD) which reduces incidence of rebleeding. Recent studies have reported the advantage of combined bypass over direct bypass for the general MMD patients. However, the effect of direct bypass and combined bypass surgery specifically for hemorrhagic-type MMD had not been investigated yet.Methods: Hemorrhagic-type MMD patients who underwent direct and combined bypass surgery with complete clinical and radiological documentation from a multicenter cohort between 2009 and 2017 were retrospectively included. Surgical methods included superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis (direct bypass), combined STA-MCA bypass with encephalodurosynangiosis (EDS), and combined STA-MCA bypass with encephaloduroarteriosynangiosis (EDAS). Matsushima standard on follow-up catheter angiography was used to assess surgical outcome. Modified Rankin Scale, incidence of rebleeding and ischemia during follow-up were recorded. Rebleeding-free survival rates between direct and combined bypass were compared by Kaplan-Meier analysis.Results: Sixty eight hemorrhagic-onset MMD patients were included in this study, among which 71 hemispheres were treated with surgery (direct bypass: 17; bypass+EDS: 24; bypass+EDAS: 30). Forty six (64.8%) hemispheres had satisfactory revascularization (Matsushima level 2–3) and 26 (36.6%) had poor neoangiogenesis. Matsushima level was not significantly different between surgical groups (P = 0.258). Good neoangiogenesis from dural grafts was achieved in 26 (36.6%) hemispheres, and good neoangiogenesis from STA grafts was only seen in 4 (out of 30, 12.5%) hemispheres. Multivariate analysis showed bypass patency [P < 0.001, OR (95%CI): 13.41 (3.28–54.80)] and dural neoangiogenesis [P < 0.001, OR (95%CI): 13.18 (3.26–53.36)] both independently contributed to good angiographic outcome. During follow-up, incidences of rebleeding or ischemic events, and re-bleeding free survival rate were not significantly different between surgical groups (P = 0.433, P = 0.559, and P = 0.997). However, patients who underwent combined bypass surgery had significantly lower mRS at follow-up comparing to patients who underwent direct bypass (P = 0.006).Conclusion: Combined bypass surgery and direct bypass surgery offered similar revascularization for hemorrhagic MMD. Bypass patency and dural angiogenesis both contributed to revascularization independently. The potential of indirect bypass to grow new vessels in hemorrhagic-MMD patients was generally limited, but dural leaflets offered better neoangiogenesis than STA grafts and was therefore recommended for surgical revascularization of hemorrhagic MMD

    Investigation on physical activation of some Mongolian coals

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    Activation characteristics of four different Mongolian coals were investigated. The coals were carbonized at temperatures of 550 °C and the obtained samples were activated by preheated steam. The pore size, pore volume and surface areas of all activated carbons (AC) have been determined by adsorption of nitrogen (N2) gas. The BET surface areas of Aduunchuluun (ACAC), Shivee Ovoo (SCAC), Baganuur (BCAC) coal and Ulaan Ovoo coals (UCAC) are 283, 205, 251 and 460 m2/g respectively. Langmuir surface area is 283 m2/g of ACAC, 230 m2/g of SCAC, 537 m2/g in UCAC and 254 m2/g in BCAC

    Quantitative assessment of cerebral connectivity deficiency and cognitive impairment in children with prenatal alcohol exposure

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    We would like to thank the patients, their parents, and technicians for their participation in this study. This research was supported by the National Natural Science Foundation (Grant No. 61601361), the Natural Science Foundation of Shaanxi Province in China (Grant No. 2017JM6013), the Shaanxi Key Laboratory of Complex System Control and Intelligent Information Processing (Contract No. SKL2017CP07), the Xi’an University of Technology, and the National Institutes of Health (NIH) grants (J. Stephen and T. Zhang—Grant Nos. P20AA017068, NCRR P20RR021938, NIGMS P20GM103472, and 1P50AA022534).Peer reviewedPostprintPostprintPublisher PD

    Nutrient co‐limitation in the subtropical Northwest Pacific

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    Nutrients limiting phytoplankton growth in the ocean are a critical control on ocean productivity and can underpin predicted responses to climate change. The extensive western subtropical North Pacific is assumed to be under strong nitrogen limitation, but this is not well supported by experimental evidence. Here, we report the results of 14 factorial nitrogen–phosphorus–iron addition experiments through the Philippine Sea, which demonstrate a gradient from nitrogen limitation in the north to nitrogen–iron co-limitation in the south. While nitrogen limited sites responded weakly to nutrient supply, co-limited sites bloomed with up to ~60-fold increases in chlorophyll a biomass that was dominated by initially undetectable diatoms. The transition in limiting nutrients and phytoplankton growth capacity was driven by a gradient in deep water nutrient supply, which was undetectable in surface concentration fields. We hypothesize that this large-scale phytoplankton response gradient is both climate sensitive and potentially important for regulating the distribution of predatory fish
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