硫氰酸钠水溶液体系的聚丙烯腈溶液凝固行为

硫氰酸钠(NaSCN)溶剂路线是国外制备高性能聚丙烯腈(PAN)基碳纤维原丝成熟的纺丝工艺路线,该技术在国内碳纤维领域尚处于发展阶段。文中采用流变仪、红外光谱研究了PAN在不同质量分数NaSCN水溶液中形成的聚合物溶液的流变性能和PAN大分子状态;溶液中NaSCN质量分数的提高,PAN溶液的黏度先减小后增大,在51%NaSCN溶液中PAN溶液的黏度最低、,用光学显微镜和X射线衍射研究了NaSCN水溶液为溶剂的PAN溶液凝固行为。研究发现,51%NaSCN溶液中,PAN大分子以最舒展状态存在,PAN分子链的31螺旋构象更多,这与溶液中硫氰酸根主要以异硫氰酸根(—N=C=S)存在有关,PAN的氰基与异硫氰酸根的—N=C形成桥键结构。随着聚合物溶液中NaSCN质量分数增加,凝固剂水在PAN溶液中的扩散速率增加,PAN溶液凝固结晶程度先增大后减小,在质量分数为51%的NaSCN水溶液中,PAN的凝固结晶规整度更优异,这与PAN以解缠伸展状态存在相关,由于流动活化能更低,PAN溶液更易发生相转变。

Metabolism of minor isoforms of prion proteins Cytosolic prion protein and transmembrane prion protein

Transmissible spongiform encephalopathy or prion disease is triggered by the conversion from cellular prion protein to pathogenic prion protein. Growing evidence has concentrated on prion protein configuration changes and their correlation with prion disease transmissibility and patho- genicity. In vivo and in vitro studies have shown that several cytosolic forms of prion protein with specific topological structure can destroy intracellular stability and contribute to prion protein pathogenicity. In this study, the latest molecular chaperone system associated with endoplasmic re- ticulum-associated protein degradation, the endoplasmic reticulum resident protein quality-control system and the ubiquitination proteasome system, is outlined. The molecular chaperone system directly correlates with the prion protein degradation pathway. Understanding the molecular mechanisms will help provide a fascinating avenue for further investigations on prion disease treatment and prion protein-induced neurodegenerative diseases.

Prognostic comparison of operative and non-operative therapies for intracerebral hemorrhage in a local hospital: Case retrospection

BACKGROUND： At present, it is satisfactory for micro-trauma craniopuncture therapy for cerebral hemorrhage to treat spontaneous intracerebral hemorrhage （ICH）. Surgical treatment can decrease fatality rate of ICH patients; however, some reports suggest that there are no obvious differences of therapeutic effects between surgical treatment and medical therapy because of various states, operative indications, contraindications and operative styles. OBJECTIVE： To observe the effect of surgical treatment on ICH prognosis, especially on fatality rate.DESIGN ： Retrospective-case study.SETTING： Huaibei People＇s Hospital.PARTICIPANTS： ① A total of 241 ICH patients selected from Huaibei People＇s Hospital from January 1988 to May 1989 were regarded as group A. They were all coincidence with Diagnostic Criteria of Intracerebral Hemorrhage in the National Cerebrovascular Disease Academic Meeting. There were 164 males and 87 females aged 34-94 years, and among them, 230 patients were older than 50 years （95.4%）. Hemorrhage sites： Among 142 patients, 85 cases had internal capsule hemorrhage, 18 external capsule hemorrhage, 15 thalamic hemorrhage, 9 cerebellar hemorrhage, 7 brain stem hemorrhage, 7 cerebral lobe hemorrhage, and 1 corpus callosum hemorrhage. Hemorrhage volume： Among 89 clear records, 44 cases had of 1-10 mL, 35 of 11-30 mL, 5 of 31-40 mL, and 5 of 41-80 mL. Except 2 patients, other ones were treated with medical operation. ② A total of 203 ICH patients selected from the same hospital from January 2003 to December 2005 were regarded as group B. Among them, 72 cases were treated with operation, but other 131 ones were treated with non-operation. They were all diagnosed with CT. There were 113 males and 90 females aged 30-88 years, and among them, 183 patients were older than 50 years （90.1%）, Hemorrhage sites： Among 203 patients, 104 cases had internal capsule hemorrhage, 17 external capsule hemorrhage, 19 thalamic hemorrhage, 9 cerebellar hemorrhage, 12 brain stem hemorrhage, 30 cerebral lobe hemorrhage, and 12 ventricular hemorrhage. Hemorrhage volume： Among 142 clear records, 53 cases had of 1- 10 mL, 42 of 11-30 mL, 16 of 31-40 mL, and 31 of 41-200 mL. Patients in both two groups consented, METHODS ： ① Therapeutic scheme： Both therapeutic methods and medicines in the both two groups were similar to each other. The main methods were as follows： dehydrating, controlling blood pressure, modifying agent of cerebral metabolism and preventing and curing complications. Therapeutic operation styles of group B： 23 patients accepted intracerebral hematoma clearance; 1 decompression by removal of cranio-bone flap; 14 centesis of lateral ventricle; 34 basilyst suction, Therapeutic styles of group A： 2 patients accepted intracerebral hematoma clearance, and others from the same as group B.② Effect estimate criteria： General recovery： Muscular force was above grade Ⅳ; meanwhile, patients could walk by themselves and care themselves partially; Improvement： Consciousness, hemiplegia and Iogagnosia took a turn for the better; Death.③ Statistical analysis： Four-table Chi-square test was used to compare differences of enumeration data. MAIN OUTCOME MEASURES： ① General prognosis of patients in the two groups; ② Prognosis of patients with various hemorrhage sites and volumes. RESULTS： All 444 patients were involved in the final analysis. ① Compared results of prognosis of patients in the two groups： Fatality rate was 18% （3/17） in group B, which was lower than that in group A [67% （12/18）, X^2=8.58, P 〈 0.05]; general recovery rate was 82% （14/17） in group B, which was higher than that in group A [11% （2/18）, X^2=17.88, P 〈 0.01]. ② Compared results of prognosis of patients with various hemorrhage sites in the two groups： Fatality rate of external capsule hemorrhage was decreased in group B as compared with that in group A （P 〈 0.05）; however, there was no significant difference at other hemorrhage sites. ③ Compared results of prognosis of patients with various hemorrhage volumes in the two groups： Fatality rate of patients with hemorrhage volume of 1-10 mL was 9% （5/53） in group B, which was lower than that in group A [64% （28/44）, X^2=7.20, P 〈 0.01]; general recovery rate was 85% （45/53） in group B, which was higher than that in group A [29% （13/44）, X^2=31,47, P 〈 0.01]. Fatality rate of patients with hemorrhage volume of 11-30 mL was 36% （15/42） in group B, which was lower than that in group A [71% （25/35）, X^2=30.64, P 〈 0.01]; general recovery rate was 50% （21/42） in group B, which was higher than that in group A [11% （4/35）, X^2=12,94, P 〈 0,01]. Fatality rate of patients with hemorrhage volume of 31-40 mL was 6% （1/16） in group B, which was lower than that in group A [60% （3/5）, X^2=9,76, P〈 0.05].CONELUSEON： Fatality rate of ICH patients who accepted more operative therapies is decreased as compared with those patients who have less operative therapies, and the prognosis is effective.

羰基化反应在大宗化学品以及精细化学品合成中的应用

简单的有机化合物如不饱和烃、卤代烃等与一氧化碳反应合成含羰基官能团化学品的羰基化反应因具有原子经济性、对环境友好及化学/区域选择性高等优点而备受关注. 综述了近几年通过发展新催化剂体系催化羰基化反应合成具有工业应用前景的大宗化学品和精细化学品的研究进展, 包括氢甲酰化反应合成醛, 氢酯化反应合成酯, 氢酰胺化反应合成酰胺, “氢甲酰化-氢化”串联反应合成醇, 以及合成酸酐、酮、酰卤等高附加值产品. 最后, 对羰基化反应在合成大宗化学品以及精细化学品中的发展前景以及存在难点进行展望, 以期发展更多类型的羰基化反应为其工业化应用提供参考.

肠道菌群与帕金森病的相关性研究

人体内肠道菌群数量庞大,参与机体物质与能量代谢,对机体的生理活动具有重要调节作用。近年来,众多研究表明,肠道菌群稳态在维持大脑和神经系统的正常功能中发挥着重要作用,肠道菌群失调与帕金森病(Parkinson’s disease,PD)等神经疾病的发作密切相关。目前,针对PD发病机制与肠道菌群失调的研究成果丰富,表明肠道菌群在PD发病中起着重要的诱导作用。本文梳理了肠道菌群紊乱与PD发生的相关国内外文献,通过深入分析PD患者肠道菌群的变化特征,讨论了PD与肠道菌群变化间的关系;同时,探讨了粪便移植技术在PD治疗中的应用,旨在为有效预防与治疗PD提供可靠的理论依据。

Observation and analysis of near-surface atmospheric aerosol optical properties in urban Beijing

Year-round measurements of the mass concentration and optical properties of fine aerosols （PM2s） from June 2009 to May 2010 at an urban site in Beijing were analyzed. The annual mean values of the PM2.5 mass concentration, absorption coefficient （Ab）, scattering coefficient （Sc） and single scattering albedo （SSA） at 525 nm were 67 ± 66 μg/m^3, 64 ± 62 Mm^-1, 360±405 Mm^-1 and 0.82±0.09, respectively. The bulk mass absorption efficiency and scattering efficiency of the PM2.5 at 525 nm were 0.78 m^2/g and 5.55 m^2]g, respectively. The Ab and Sc showed a similar diurnal variation with a maximum at night and a minimum in the afternoon, whereas SSA displayed an opposite diurnal pattern. Significant increases in the Ab and Sc were observed in pollution episodes caused by the accumulation of pollutants from both local and regional sources under unfavorable weather conditions. Aerosol loadings in dust events increased by several times in the spring, which had limited effects on the Ab and Sc due to the low absorption and scattering efficiency of dust particles. The frequency of haze days was the highest in autumn because of the high aerosol absorption and scattering under unfavorable weather conditions. The daily PM2.5 concentration should be controlled to a level lower than 64 μg/m^3 to prevent the occurrence of haze days according to its exponentially decreased relationship with visibility.

Terrestrial Near-Surface Wind Speed Variations in China:Research Progress and Prospects

Changes in terrestrial near-surface wind speed(NSWS)are indicative of the concentrated net effect of climate change and anthropogenic activities.Investigating change mechanisms of NSWS not only furthers the understanding of how the atmosphere changes and improves the climate analysis and projection,but also aids the evaluation and application of wind energy resources.Recent advances in studies of the changes and associated mechanisms of the NSWS over China are reviewed in this paper.Some new results have been achieved in understanding the behaviors of the NSWS changes.The NSWS over China has experienced a decrease in the past 40 years and a recovery in the recent decade,exhibiting large regional and seasonal differences.Understanding of the mechanisms of the NSWS changes has been improved in several aspects;for example,it is found that the reduced NSWS over China is due to the weakening of the pressure-gradient force(PGF)attributed to variations in large-scale ocean–atmosphere circulations(LOACs)as well as the increase of surface roughness due to the land use and cover change(LUCC).The main methods used to analyze the NSWS changes and corresponding mechanisms are also elucidated and discussed.However,studies are still lacking on the mechanisms for multi-timescale(seasonal,interannual,decadal,multidecadal)variations in the NSWS over China,and it remains unknown about the contributions of different forcing factors to the NSWS changes.Finally,key scientific issues regarding our understanding of the NSWS changes are proposed for future investigation.

Comparisons of urban-related warming in Beijing using different methods to calculate the daily mean temperature

To evaluate the contribution of urban surface expansion to regional warming using different methods to calculate the daily mean surface air temperature(SAT), satellite-based images displaying urban surface expansion over the past 37 years(1980–2016) across China were collected for use in nested numerical experiments using the weather research and forecasting(WRF) regional climate model. The contribution of urban surface expansion to urban-related warming was determined using the daily mean SAT averages based on four time records each day(00, 06, 12, and 18 h UTC, T_4) and averages of the SAT maximum(Tmax) and minimum(Tmin)(Txn). The contribution of urban surface expansion to urban-related warming(relative value) in Beijing was 0.110°C per decade(22.8% of total warming) for T_4 and 0.094°C per decade(20.2%) for Txn. The values obtained when using T_4 were larger than those obtained when using Txn. Differences in the urban-related warming calculated using T_4 and Txncould be attributed to the smaller changing trends in Txnin the urban-surface expansion experiment, which resulted from a large changing trend in Tminand a much smaller changing trend in Tmax. The changes in the diurnal cycle of the energy budget due to urban surface expansion induced changes in the diurnal cycle of SAT, as evidenced by the four time records each day, as well as Tmaxand Tmin. This was especially true for periods of intense urban surface expansion, although the annual mean SAT calculated using Txnwas larger than that calculated using T_4. The increase in impervious area(walls, streets, etc.) due to urban surface expansion, as well as the widespread use of building materials with a large heat capacity resulted in a marked increase in ground heat flux in the daytime. This restricted the increase in SAT in the daytime, but promoted it at night. The increases in SAT due to urban surface expansion were not symmetrical, being smaller in the daytime and larger at night.

Kinetics of microwave-enhanced oxidation of phenol by hydrogen peroxide

Aqueous solutions of phenol were oxidized by hydrogen peroxide assisted by microwave(MW)irradiation.A simple kinetic model for the overall degradation of phenol in the presence of excess H_(2)O_(2) is proposed in which the degradation rate of phenol is expressed as a linear function of the concentrations of phenol and H_(2)O_(2).A detailed parametric study showed that the degradation rate of phenol increased with increasing[H_(2)O_(2)]until saturation was observed.Phenol degradation followed apparent zero-order kinetics under MW radiation or H_(2)O_(2) oxidation.However,after 90 min of irradiation,the observed kinetics shifted to pseudo first order.The overall reaction rates were significantly enhanced in the combined MW/H_(2)O_(2) system,mainly because microwave could accelerate H_(2)O_(2) to generate hydroxyl radical(·OH)and other reactive oxygen intermediates.The observed synergetic effects of the MW/H_(2)O_(2) process resulted in an increased in the net reaction rate by a factor of 5.75.When hydrogen peroxide is present in a large stoichiometric excess,the time required to achieve complete mineralization is reduced significantly.