船舶反渗透海水淡化水的水质检测及卫生学分析

目的:分析船舶反渗透海水淡化水的水质,从卫生学探讨船舶反渗透淡化水作为饮用水长期饮用对船员健康的可能影响。方法:水质分析按照《生活饮用水标准检验方法》(GB/T5750-2006)进行,并比较船舶反渗透海水淡化水、港口直供水、舱贮饮用水的水质差异。结果:船舶反渗透海水淡化水中氟化物<0.01 mg/L,总硬度<1 mg/L,显著低于港口直供水和舱贮饮用水;同时硼为1.03 mg/L,超过《生活饮用水卫生标准》(GB5749-2006)限值的两倍。结论:从卫生学分析,长期饮用船舶反渗透海水淡化水对船员的健康可能有影响,建议适度增加船舶反渗透海水淡化水中氟、钙、镁等营养元素水平,同时进一步脱除硼,从而更好地保护船员的身心健康。     

北京市某区浅层自备井水总硬度的影响因素分析

目的 了解北京某区浅层自备水井中总硬度含量的影响因素.方法 选取北京某区5眼浅层自备井和1眼深层自来水厂水源井.分别于2004-2010年枯水期(4、5月)和丰水期(8、9月),在井口泵房采集井水水样,检测总硬度、pH值、氯化物、硫酸盐.结果 共采集自备井水样70件,总硬度合格36件,合格率仅为51.43%.不同年度间...     

Combined Characterization of the Time Response of Impression Materials via Traditional and FTIR Measurements

We investigated the temporal response of four dental impression materials, namely three siloxanes (Imprint 4, Flexitime, Aquasil) and one polyether (Impregum). The null hypothesis was that the nominal working times are confirmed by instrumental laboratory tests. We also aimed to identify alternative techniques with strong physical-chemical background for the assessment of temporal response. Traditional characterization was carried out by shark fin test device and durometer at both ambient and body temperature. Additionally, Fourier-transform infrared spectroscopy was performed at room temperature. From shark fin height and Shore hardness versus time the working time and the setting time of the materials were evaluated, respectively. These were in reasonable agreement with the nominal values, except for Impregum, which showed longer working time. Spectroscopy confirmed the different character of the two types of materials, and provided for Imprint 4 and Aquasil an independent evaluation of both evolution times, consistent with the results of the other techniques. Shark fin test and durometer measurements showed deviations in setting time, low sensitivity to temperature for Flexitime, and longer working time at higher temperature for Impregum. Deviations of working time appear in operating conditions from what specified by the manufacturers. Fourier-transform infrared spectroscopy can provide insight in the correlation between material properties and their composition and structure.     

FibroScan对慢性乙型肝炎肝纤维化诊断的临床价值

目的探讨肝脏瞬时弹性扫描仪(FibroScan)对慢性乙型肝炎(chronic hepatitis B,CHB)肝纤维化的诊断价值。方法对80例行肝脏穿刺检查的CHB患者进行FibroScan检测,记录所检测到的肝脏硬度值。肝纤维化程度分为无或轻度肝纤维化(S0~S1期)、显著肝纤维化(S2~S4期)、严重肝纤维化(S3~S4期)和早期肝硬化(S4期)。以肝脏活体组织检查病理结果为"金标准",绘制受试者工作特征曲线(receiver-operating characteristic curve,ROC曲线),计算ROC曲线下面积(area under ROC curve,AUROC),评价FibroScan对CHB患者肝纤维化的诊断价值。结果肝脏硬度值与肝脏病理分期呈正相关(rs=0.739,P0.01)。FibroScan对显著肝纤维化、严重肝纤维化和早期肝硬化的AUROC值分别为0.865、0.940和0.944。结论 FibroScan可以较准确地估计CHB患者的肝纤维化程度,部分替代有创性的肝脏活体组织检查,对CHB患者肝纤维化的诊断和治疗有指导意义。     

Investigation of the Mechanical Properties of Mn-Alloyed Tin-Silver-Copper Solder Solidified with Different Cooling Rates

Manganese can be an optimal alloying addition in lead-free SAC (SnAgCu) solder alloys because of its low price and harmless nature. In this research, the mechanical properties of the novel SAC0307 (Sn/Ag0.3/Cu0.7) alloyed with 0.7 wt.% Mn (designated as SAC0307-Mn07) and those of the traditionally used SAC305 (Sn96.5/Ag3/Cu0.5) solder alloys were investigated by analyzing the shear force and Vickers hardness of reflowed solder balls. During the preparation of the reflowed solder balls, different cooling rates were used in the range from 2.7 K/s to 14.7 K/s. After measuring the shear force and the Vickers hardness, the structures of the fracture surfaces and the intermetallic layer were investigated by SEM (Scanning Electron Microscopy). The mechanical property measurements showed lower shear force for the SAC0307-Mn07 alloy (20–25 N) compared with the SAC305 alloy (27–35 N), independent of the cooling rate. However, the SAC0307-Mn07 alloy was softer; its Vickers hardness was between 12 and 13 HV, whereas the Vickers hardness of the SAC305 alloy was between 19 and 20 HV. In addition, structural analyses revealed rougher intermetallic compound layers in the case of the SAC0307-Mn07 alloy, which can inhibit the propagation of cracks at the solder–substrate interface. These two properties of SAC0307-Mn07 alloy, the softer nature and the rougher intermetallic layer, might result in better thermomechanical behavior of the solder joints during the lifetime of electronic devices.     

玻璃离子水门汀加入银合金粉后对其抗压强度和表面硬度的影响

目的：观察玻璃离子水门汀（ＧＩＣ）中直接加入不同比例银合金粉后的机械性能。方法：测试实验材料的抗压强度和表面硬度。结果：加入银合金粉后ＧＩＣ抗压强度和表面硬度明显下降，并且加入量越大，下降越明显。结论：ＧＩＣ中直接加入银合金粉不能改善ＧＩＣ的机械性能。     

低邵氏硬度SY复合型硅橡胶的配方筛选

目的 :得到邵氏硬度分别为 18、2 0、2 2的复合型硅橡胶赝复材料 ,以满足特定缺损部位的赝复体硬度要求。方法 :质量比均匀混合 ,加入适量的混合交联剂固化并加工成长方形试样。测试其邵氏硬度 ,选出硬度值最接近 18、2 0、2 2的三种硅橡胶试样 ,确定相应的配方比例。结果 :当SY复合型硅橡胶邵氏硬度为 18.1± 3 .6、19.9± 4.1、2 2 .0± 2 .8时 ,SY 1硅橡胶和C型硅橡胶的配方比例依次为 76∶2 4、78∶2 2、84∶16。结论 :按照适当比例进行SY 1硅橡胶和C型硅橡胶的并用 ,可以得到邵氏硬度分别为 18、2 0、2 2的低邵氏硬度SY复合型硅橡胶赝复材料 ,满足不同的赝复临床需要     

Effects of low power red laser on induced-dental caries in rats

OBJECTIVE: The purpose of this study was to investigate the effects of low power red laser associated with acidulated phosphate fluoride on the development of induced-dental caries in rats. DESIGN: Dental caries were induced in molars of 40 rats divided into five groups: control group (CG), the teeth were not submitted to any treatment; laser group (LG), teeth were irradiated with a low power red laser (LPRL), power of 30 mW and dose of 5 J/cm(2); fluoride group (FG), teeth were treated with topical acidulated phosphate fluoride (APF) 1.23% applied for 4 min; laser+fluoride group (LFG), teeth were irradiated with LPRL followed by APF; fluoride+laser group (FLG), teeth were treated with APF followed by LPRL. The animals were killed after 48 days, and the first and second molars were extracted to analyze the caries lesion area, microhardness, and calcium and phosphorus ratio. RESULTS: There were no statistical differences among FG, LFG, and FLG regarding to caries area and microhardness, although the caries area were smaller in LFG. Ca/P ratio did not show significant differences among all groups. CONCLUSIONS: Although LPRL before APF application appeared to diminish the caries progression, LPRL did not present any additional benefit compared with acidulated phosphate fluoride on the prevention of induced-dental caries in rats.     

Burger Model as the Best Option for Modeling of Viscoelastic Behavior of Resists for Nanoimprint Lithography

In this study, Atomic Force Microscopy-based nanoindentation (AFM-NI) with diamond-like carbon (DLC) coated tip was used to analyze the mechanical response of poly(methyl methacrylate) (PMMA) thin films (thicknesses: 235 and 513 nm) on a silicon substrate. Then, Oliver and Pharr (OP) model was used to calculate hardness and Young’s modulus, while three different Static Linear Solid models were used to fit the creep curve and measure creep compliance, Young’s modulus, and viscosity. Values were compared with each other, and the best-suited method was suggested. The impact of four temperatures below the glass transition temperature and varied indentation depth on the mechanical properties has been analyzed. The results show high sensitivity on experiment parameters and there is a clear difference between thin and thick film. According to the requirements in the nanoimprint lithography (NIL), the ratio of hardness at demolding temperature to viscosity at molding temperature was introduced as a simple parameter for prediction of resist suitability for NIL. Finally, thinner PMMA film was tentatively attributed as more suitable for NIL.