一阶导数高速脉冲极谱法用于盐酸普鲁卡因的定量分析

研究了一阶导数高速脉冲极谱法,并运用于盐酸普鲁卡因及其注射制剂的定量分析。在-0.04 V(对 Ag/AgCl)处出现的良好导数峰,于1.0～6.0×10~(-4)mol/L 范围内,导数峰电流与浓度呈线性关系。检测限为3.0×10~(-8)mol/L。操作简便、快速、灵敏,结果准确。     

高速铁路软土地基处理对策及效果分析

介绍了沪宁段铁路沿线的软土分布特征,将沿线软土地基分为4类,并从技术和经济两方面,分别对各类软土地基的处理进行了分析和比较,提出了相应的处理建议。     

高速逆流色谱在天然产物分离中的应用

综述了高速逆流色谱在天然产物有效成分分离中的新应用.     

天然产物分离中高速逆流色谱溶剂体系的研究进展

根据溶剂体系的极性与分离的天然产物的关系,本文对高速逆流色谱中使用的溶剂系统进行了归纳总结,不仅对快速选择溶剂体系分离天然产物起到了一定的指导作用,而且为今后高速逆流色谱溶剂体系的研究提供了方便。     

大孔吸附树脂-高速逆流色谱法分离纯化玄参中哈巴俄苷和斩龙剑苷A

目的 以玄参的干燥根为原料,建立大孔吸附树脂-高速逆流色谱法(HSCCC)分离纯化玄参中哈巴俄苷与斩龙剑苷A的方法。方法 玄参粗提物先经过大孔吸附树脂初步分离,富集目标化合物。然后以正丁醇-乙酸乙酯-水(1∶9∶10)为溶剂体系,上相为固定相,下相为流动相,流速1.5 mL·min^-1,检测波长210 nm,利用制备型HSCCC分离纯化哈巴俄苷和斩龙剑苷A。结果 经过大孔吸附树脂-高速逆流色谱法分离后,一次性得到哈巴俄苷和斩龙剑苷A,经HPLC检测其纯度分别为98.1%和97.2%。经¹H-NMR和¹³C-NMR鉴定结构为哈巴俄苷和斩龙剑苷A。结论 该方法能够简便、高效地制备玄参中的哈巴俄苷和斩龙剑苷A。     

Study on the Interaction between Wheel Polygon and Rail Corrugation in High-Speed Railways

The wheel polygonization and rail corrugation are typical wheel–rail periodic wear problems, which seriously affect the safe operation of high-speed railways. In the present paper, the interaction between the wheel polygon and the rail corrugation in the long-slope section of high-speed railways is mainly studied based on theory of friction coupling vibration. Firstly, the simulation model of the wheel–rail contact model is established, as well as the polygonal wear of the wheel and the corrugated wear of the rail. Then, the stability analyses of the wheel–rail system with periodic wear are studied, in which the four working conditions of smooth rail–smooth wheel, polygonal wheel–smooth rail, smooth wheel–corrugated rail and polygonal wheel–corrugated rail are compared. Finally, the competition mechanisms between the wheel polygon and rail corrugation under different parameters are discussed, including the wheel–rail friction coefficient and the depth of periodic wear of the wheel–rail system. The numerical results show that both the periodic wear of the wheel and rail with certain relevance will increase the friction coupling vibration of the wheel–rail system, which may aggravate the subsequent relevant wheel polygonal and rail corrugation wear. With the increase of the friction coefficient between wheel and rail, as well as the depth of the wheel polygon and rail corrugation, the vibration trend of the friction coupling vibration of the wheel–rail system increases gradually. Moreover, the proportion of the wheel polygon’s influence on the friction coupling vibration of the wheel–rail system is greater than that of rail corrugation.     

Virtual occlusion in orthognathic surgery

The aim of this retrospective study was to determine whether a virtually created occlusion is as accurate as a conventionally created occlusion. Seventeen orthognathic patients were included in the study, which was conducted in a university clinic. Plaster cast models were obtained and digitized. Two experienced observers created the conventional (gold standard) and virtual occlusion to assess inter-observer variability. One observer created the conventional and virtual occlusion a second time to assess the intra-observer variability. The criterion for accepting the virtual occlusion was that the difference between the gold standard and the virtual occlusion was not larger than the intra-observer variability for the gold standard. A non-parametric Kruskal–Wallis H test was performed to detect statistically significant differences between the intra- and inter-observer groups for both the conventional and virtual occlusion. No statistically significant differences were found between the different groups. The difference between the conventional and virtual occlusion group was 0.20 mm larger than the intra-observer variability of the gold standard. The virtual occlusion tool presented here can be utilized in daily clinical practice and makes the use of physical dental models redundant.     

离心机模拟连续推拉动作训练方法研究

目的建立贴近实战化训练模式的连续推拉动作(PPM)离心机训练方法。方法调研提炼飞行训练中典型的PPM载荷参数,编制离心机模拟连续PPM曲线。16名战斗机飞行员作为志愿者,A组6名,采用-1Gz/3s→+6Gz/10s→2Gz/10s→0Gz/3s→+4.5Gz/10s→2Gz/10s→0.5Gz/3s→+5 Gz/10s连续PPM曲线,B组10名,采用-1Gz/3s→+6Gz/10s→2Gz/10s→0Gz/3s→+4.5Gz/10s→2Gz/10s→-1Gz/3s→+7Gz/5s连续PPM曲线(根据A组建议对曲线进行了改进),进行了HP动作对抗连续PPM离心机训练。志愿者在相对-Gz(小于+1Gz)暴露时采用HP动作的呼吸方式,在向+Gz转换时开始做较用力的HP动作,记录分析+Gz耐力、心率(HR)等指标的变化。结果A组6名志愿者均完成了连续PPM离心机训练,对PPM曲线提出了改进建议。B组9名志愿者采用改进的连续PPM曲线完成离心机训练。两组在相对-Gz时的HR均显著高于安静状态(P<0.05),连续PPM暴露时的HR变化趋势说明心血管调节有持续效应,其适应负荷有滞后。结论建立了高性能战斗机飞行员连续PPM离心机训练方法,模拟连续PPM曲线中不同水平-Gz与+Gz交替作用的模式更能体现实战化训练中长时间反复空战的特点,将应用于后续飞行员离心机训练。     

微创去腐技术治疗患者龋齿的临床效果评价

目的:分析微创去腐技术治疗患者龋齿的临床效果。方法:将98例龋齿患者分为观察组和对照组。观察组患者52例,采用微创去腐技术治疗龋齿;对照组患者46例,采用传统高速牙钻去腐治疗龋齿。结果:观察组患者的疼痛评分低于对照组,两组患者的单牙治疗时间、治疗后20个月时充填物完好率对比P>0.05,并发症对比P<0.05。结论:微创去腐技术治疗龋齿患者效果显著。     

Toxicology of 3-epi-deoxynivalenol,a deoxynivalenol-transformation product by Devosia mutans 17-2-E-8

Microbial detoxification of deoxynivalenol (DON) represents a new approach to treating DON-contaminated grains. A bacterium Devosia mutans 17-2-E-8 was capable of completely transforming DON into a major product 3-epi-DON and a minor product 3-keto-DON. Evaluation of toxicities of these DON-transformation products is an important part of hazard characterization prior to commercialization of the biotransformation application. Cytotoxicities of the products were demonstrated by two assays: a MTT bioassay assessing cell viability and a BrdU assay assessing DNA synthesis. Compared with DON, the IC₅₀ values of 3-epi-DON and 3-keto-DON were respectively 357 and 3.03 times higher in the MTT bioassay, and were respectively 1181 and 4.54 times higher in the BrdU bioassay. Toxicological effects of 14-day oral exposure of the B6C3F₁ mouse to DON and 3-epi-DON were also investigated. Overall, there were no differences between the control (free of toxin) and the 25 mg/kg bw/day or 100 mg/kg bw/day 3-epi-DON treatments in body and organ weights, hematology and organ histopathology. However, in mice exposed to DON (2 mg/kg bw/day), white blood cell numbers and serum immunoglobulin levels were altered relative to controls, and lesions were observed in adrenals, thymus, stomach, spleen and colon. Taken together, in vitro and in vivo studies indicate that 3-epi-DON is substantially less toxic than DON.