甘油浓度对红细胞冻干保存效果的影响

目的探讨甘油浓度浓度对红细胞冷冻干燥保存的回收率、溶血率及残余水含量的关系。方法以甘油浓度分别为3%、6%、9%、12%、15%、18%、21%(w/v)的冻干保护剂处理红细胞,冻干,用显微镜观察细胞形态、血细胞计数仪检测细胞数、分光光度计测定游离血红蛋白量,分析细胞复水后红细胞计数、溶血情况。用热重法测定冻干红细胞水分含量,分析不同保护剂组红细胞的水分含量变化情况。结果复水后红细胞形态正常,甘油浓度为9%、12%、15%时,红细胞回收率分别为(77.08±9.41)%、(84.37±3.42)%、(80.21±9.20)%,红细胞溶血率分别为(19.82±2.23)%、(17.66±1.17)%、(15.86±2.23)%,相应的冻干红细胞残余水分含量为(19.43±1.36)%、(22.89±1.57)%、(26.17±1.09)%。结论保护剂中甘油浓度影响红细胞冻干保存的效果;甘油浓度为(9-15)%时对冻干保存的红细胞损伤较小;冻干红细胞残余水分含量随保护剂中甘油浓度的增高而增高。     

Ultrasonic measurement of the effects of light irradiation and presence of water on the polymerization of self‐adhesive resin cement

Self‐adhesive resin cements are useful in restorations because they reduce the number of clinical steps involved in the restoration process. This study evaluated, using ultrasonic measurements, the influence of light irradiation and the presence of water on the polymerization behavior and elastic modulus of a self‐adhesive resin cement. A self‐adhesive resin cement (RelyX Unicem 2 Automix) or a resin cement (RelyX ARC) was inserted into a transparent mold on a sample stage, and the presence of water and effect of light‐irradiation were evaluated. The transit time of a sonic wave through the cement disk was divided by the specimen thickness to obtain the sonic velocity, and longitudinal and shear waves were used to determine the elastic modulus. When the resin cements were light‐irradiated, the sonic velocity rapidly increased and plateaued at 2,500–2,700 m s^?1. When the cements were not irradiated, the rates of increase in the sonic velocity were reduced. When water was applied to the sample stage, the sonic velocity was reduced. The elastic modulus values of the specimens ranged from 9.9 to 15.9 GPa after 24 h. The polymerization behavior of self‐adhesive resin cements is affected by the polymerization mode and the presence of water.     

Effects of Loaded End Distance and Moisture Content on the Behavior of Bolted Connections in Squared and Round Timber Subjected to Tension Parallel to the Grain

This article presents the results of static tests on bolted connections in squared and round timber with inserted steel plates. The experiment evaluates structural timber connections with different distances between the fastener and the loaded end at different moisture contents. Specimens were loaded by tension parallel to the grain and load–deformation diagrams were recorded. Fifty-six specimens with three different distances between the fastener and the loaded end, at different moisture contents, were tested. The results were statistically evaluated using regression analysis, complemented with load–deformation curves, and compared with calculations according to the valid standard for design of timber structures. A decrease in the evaluated load-carrying capacity with increasing moisture content was confirmed experimentally. A slight increase in the evaluated load-carrying capacity with increasing fastener distance from the loaded end was found.     

温度对 3 种中药浸膏片包衣工艺参数的影 响简

目的 研究温度对3种中药浸膏片包衣工艺的影响.方法 将素片置恒湿变温环境中,不同时间称定片重,记录、计算吸湿增重,分析吸湿数据;将素片置干燥环境中,其余条件相同情况下,记录、计算减重百分率、绘制减重速率曲线图.结果 冠心平片和健肾片的吸湿速率随温度升高而降低,而保肾片的吸湿速率随温度升高而升高;保肾片和冠心平片在60℃的减重百分率大于50℃的减重百分率,而健肾片的减重百分率在50℃和60℃之间变化不明显.结论 吸湿性参数、干燥速率参数可为包衣工艺参数的制订提供科学数据.     

Efficacy of heat and moisture exchangers in preventing ventilator-associated pneumonia: meta-analysis of randomized controlled trials

Objective Several randomized controlled trials (RCT) have examined the effect of antibacterial humidification strategies, particularly the replacement of heated humidifiers (HH) by heat and moisture exchangers (HME), in preventing ventilator-associated pneumonia (VAP). The present meta-analysis reviews these RCTs.Methods RCTs were identified by searching the Medline and Cochrane Central Register of Controlled Trials databases from 1990 to 2003. We included RCTs using HMEs in the treatment group and HHs in the control group and reporting the incidence of pneumonia as a study outcome. Two investigators independently abstracted key data on design, population, intervention and outcome of the studies.Results Between 1990 and 2003 eight RCTs met the inclusion criteria of this analysis. Pooling the results from these studies revealed a reduction in the relative risk of VAP in the HME group (0.7), particularly in MV with a duration of at least 7 days (five RCTs, relative risk 0.57).Conclusions This meta-analysis found a significant reduction in the incidence of VAP in patients humidified with HMEs during MV, particularly in patients ventilated for 7 days or longer. This finding is limited by the exclusion of patients at high risk for airway occlusion from some of the studies. Moreover, contraindications (tenacious secretions, airway obstructive disease, hypothermia) and technical issues of HMEs must be considered. Further RCTs are necessary to examine the wider applicability of HMEs and their extended use.     

下呼吸道感染与吸氧湿化液的相关性研究

目的:探讨预防下呼吸道感染具体有效的措施,对吸入性下呼吸道感染进行目标性监测。方法:将200例吸氧患者随机分为两组各100例,分别使用研究改进的500m l瓶/无菌专用吸氧湿化液及常规塑料桶盛装无菌蒸馏水。对两组下呼吸道感染率、吸氧时间长短与下呼吸道感染的关系、湿化液染菌情况进行统计分析。结果:改进组发生下呼吸道感染20例,占20%,取标本56份送检无1例染菌;对照组发生下呼吸道感染38例,占38%,取标本30份送检全部染菌。两组比较有显著性差异(P<0.01,P<0.05)。结论:使用研究改进的吸氧湿化液能有效控制吸入性下呼吸道感染。     

Molecular Dynamic Investigations on the Adhesion Behaviors of Asphalt Mastic–Aggregate Interface

The asphalt mastic–aggregate interface plays an essential role in determining the service performance of asphalt mixtures. The objective of this paper was to investigate the adhesion behaviors and mechanism between asphalt mastic and aggregate based on molecular dynamic (MD) simulations. First, the asphalt mastic model considering the actual mass ratio of filler to asphalt (F/A) condition was established and validated in terms of thermodynamic properties. Second, the molecular arrangement characteristics of polar components on the aggregate substrate were analyzed by radial distribution function (RDF), relative concentration (RC), and mean square displacement (MSD). Third, the interfacial adhesion ability between asphalt and aggregate was quantitively evaluated based on the work of adhesion. Finally, the coupling effect of moisture and temperature on interfacial adhesion behaviors was investigated to explore the adhesion failure characteristics of the asphalt–aggregate interface. The results demonstrate that the thermodynamic properties could be employed to validate the reliability of the asphalt mastic model. The self-aggregation degree of polar components in base asphalt could be significantly increased with the addition of silica particles, exhibiting a change of configuration from “parallel arrangement” into “stack distribution” due to the high polarity of silica particles. The polar components in asphalt mastic exhibit a more uniform distribution state and lower mobility capability than base asphalt owing to the adsorption effect of silica particles. Silica particles with amounts of residual charges could significantly increase the electrostatic energy of the asphalt mastic–aggregate interface, contributing to an improvement of the adhesion between asphalt mastic and aggregate. The increase of temperature enhances the work of adhesion of the asphalt mastic–aggregate interface, which is opposite to that of the base asphalt–aggregate interface. The asphalt mastic exhibits a greater sensitivity to interfacial moisture damage than base asphalt. The findings would provide insights into a better understanding on the micro adhesion mechanism of the asphalt mastic–aggregate interface.     

叶酸水分测定方法的研究

目的: 对叶酸的水分测定方法进行研究。方法:采用热重分析法(TG)、差示扫描量热法(DSC)等方法对叶酸的热力学行为进行研究,并建立了一个新的卡式炉-卡尔费休法测定水分的方法。结果: 采用新建立的方法测定国内及美国药典会(USP)叶酸对照品水分,结果分别为8.13%与8.00%,标准偏差分别为0.74%与0.28%(n=3)。结论: 本文建立的卡式炉-卡尔费休法方法简单方便,准确可靠,适合批量样品的测定,为叶酸对照品的标定及其原料的质量控制提供依据。     

白芍总苷对皮肤机械屏障障碍小鼠皮肤屏障功能的影响

目的:研究白芍总苷对小鼠皮肤机械屏障受损的修复作用及可能机制。方法:雌性ICR小鼠随机分为正常组、模型组、白芍总苷低剂量(0.2 mg/g)组、白芍总苷高剂量(0.4 mg/g)组和糠酸莫米松(1 mg/g)组,每组12只。除正常组外,其余各组采用胶带法诱导小鼠皮肤机械屏障损伤模型,连续5 d。第6天起,各组给予相应药物外用干预,0.3 g/只,正常组和模型组给予等量水凝胶基质,连续14 d。末次给药后,检测受损皮肤的含水量、油脂含量及pH值。分离受损皮肤组织,HE染色后光镜下观察皮肤组织形态学变化,试剂盒检测皮肤组织白介素-6(IL-6)和神经酰胺的含量。结果:①HE染色观察显示,模型组小鼠皮肤炎症细胞浸润,角质层增厚,腺上皮细胞增多;白芍总苷干预后上述病变情况明显改善,高剂量组作用更为显著。②与正常组相比,模型组小鼠受损皮肤的含水量、油脂含量及pH值明显降低(P0.01);与模型组相比,糠酸莫米松组及白芍总苷高、低剂量组小鼠的皮肤含水量均显著升高(P0.05,P0.01),糠酸莫米松组及白芍总苷高剂量组小鼠皮肤的油脂含量亦显著升高(P0.01)。③与正常组相比,模型组小鼠皮肤组织IL-6含量显著升高(P0.05),神经酰胺含量显著降低(P0.01);与模型组相比,白芍总苷高剂量组和糠酸莫米松组小鼠皮肤组织的IL-6含量明显降低(P0.05,P0.01),神经酰胺含量明显升高(P0.01)。结论:白芍总苷可修复皮肤机械屏障受损,其机制可能与降低角质层中炎症介质IL-6的含量、增加角质层中神经酰胺的含量有关。