离子色谱同时测定果汁中22种糖、糖醇和醇

目的建立积分安培-离子色谱法同时测果汁中22种糖、糖醇和醇定的方法。方法在流速为0.40 mL/min, pH值在6.5～8.6,柱温为30℃条件下,在CarboPacTM MA1(4 mm×250 mm)色谱柱中进行分离。结果 22种组分在测定浓度范围内具有良好的线性关系(r~20.999);除了甲醇外,其他21种组分检出限在0.006～0.203 mg/L之间;在0.50、1.00、5.00 mg/L 3个添加浓度水平下,回收率为75.83%～105.89%,相对标准偏差(RSD)在1.03%～10.39%范围内。结论该方法简便、快速、准确、灵敏,完全适于果汁中22种糖、糖醇和醇的分析测定。     

基于采动和承压水作用下断层突水关键路径的力学分析

 断层突水是煤矿典型的动力灾害,是煤岩体在采动和承压水共同作用下失稳破坏过程。论文针对导水断层缩短了煤层和含水层距离特点,建立了断层突水的关键路径力学模型。将极限平衡理论和尖点突变理论引入断层突水分析,建立了承压水及采动影响下断层突水关键部位失稳破坏模型,获得了断层突水的力学判据,以及防突煤柱预留临界宽度。同时分析了断层参数、煤柱参数对突水条件的影响规律     

常用V型组合杆密封液压缸压盖螺钉断裂原因的分析

分析了常用V型组合杆密封液压缸压盖螺钉断裂的各种原因,提醒液压缸设计师注意完善设计细节、制造者应提高产品质量监控意识,液压缸用户应提供较为完善的订货工况描述.     

四苯基卟啉铟纳米材料的制备及其光学传感性能研究

在水/二甲基亚砜(DMSO)的混合溶液体系中,利用自组装方法,使5,10,15,20-四苯基卟啉铟(InTPP)分子聚集成纳米材料,并研究了其最优制备温度为50℃。通过场发射扫描电子显微镜(FE-SEM)对铟卟啉纳米材料的表面形貌进行了研究,可获得粒径为100～200nm的棒状铟卟啉纳米材料。利用紫外-可见光谱分析了铟卟啉单体与纳米材料光学性质的差别:在紫外-可见光谱中,铟卟啉纳米分散体系的Soret带吸收峰从原来的423nm分别红移到433和453nm,吸光值明显减小,峰形呈劈裂状且明显变宽。利用紫外-可见光谱对铟卟啉的光学检测性能进行了研究,将铟卟啉单体和纳米溶液体系对低浓度甲基膦酸二甲酯(DMMP)的检测效果进行了对比,结果显示铟卟啉纳米溶液体系的检测效果明显优于单体。     

浅谈土壤源热泵系统的发展及其应用

概述了土壤源热泵系统的特点，阐述了土壤源热泵技术在国内外的发展、研究现状，最后介绍了土壤源热泵技术在发展中面临的问题及在制冷空调中的广阔应用前景。     

A randomized, controlled trial of a behavioral intervention to prevent sexually transmitted disease among minority women

Using annual bite-wing radiographs, the incidence and progression of approximal caries (4d-7m) were assessed longitudinally in teenagers and adolescents whose treatment had been based on remineralizing rather than restorative strategies. A closed cohort of 536 children initially was followed from 11 to 22 years of age. The scoring system was: 0 = no visible radiolucency; 1-2 = radiolucency in the enamel up to the enamel-dentin border; 3 = radiolucency with a broken enamel-dentin border but with no obvious progression in the dentin; 4 = radiolucency with obvious spread in the outer half of the dentin, and 5 = radiolucency in the inner half of the dentin. Caries rates were estimated as the number of new lesions/100 tooth surface-years, and the Kaplan-Meier estimate was used to calculate the cumulative survival time of each approximal surface. Three events were used: the transitions from states 0 to 2, 2 to 4 and 3 to 4. The results showed a considerable variation between the surfaces in both caries rates and survival time. For all surfaces combined, the median caries rate from state 0 to 2 was 3.9 new lesions/100 tooth surface-years; from state 2 to 4, the rate was 5.4, and from state 3 to 4 it was 20.3. Of the sound surfaces (state 0), 75% survived 6.3 years without reaching state 2. Given state 2, 75% survived 4.8 years without reaching the outer half of the dentin (state 4), while given a lesion at the enamel-dentin border (state 3), 75% survived 1.3 years without doing the same. The median survival time of lesions from state 3 to 4 was 3.1 years. The group with DMFSappr>1 at the age of 11-12 years had a risk of new approximal enamel lesions (state 0-2) that was 2.5 times greater than that of the group with DMFSappr = 0-1.     

Correlation between in vitro and in vivo parameters of commercial paracetamol tablets

Three leading and competitive commercial products of paracetamol tablets coded as brands A, B and C (A, being the innovator product) in the country were evaluated for their in vitro properties and in vivo comparative bioavailability. The studies included chemical equivalence, hardness, disintegration time, dissolution rate and systemic availability among eight healthy volunteers. The disintegration times were 2.1 min for brand A, 5.7 min for brand B and 36.2 min for brand C. The dissolution rate (T70) were 33.0 min, 74.5 min and 56.5 min for brands A, B and C, respectively. While brand A passed all the in vitro tests as specified in the official monograph, brand B failed only the dissolution rate test and brand C failed both the disintegration and dissolution tests. These significant differences observed among the products after in vitro tests were not reflected in the in vivo availability. While the absorption rate (indicated by tmax) of brand C was significantly faster (i.e. shorter) than those of Brands A and B, the extent of absorption (indicated by AUC) was comparable among the three brands. The relative bioavailabilities (with respect to brand A) were 92 and 91% for brands B and C, respectively indicating that the products were bioequivalent. Comparison of the in vitro and in vivo data suggest that the systemic absorption of paracetamol may not be dissolution--rate limited and that using in vitro dissolution rate studies alone to establish bioequivalency of paracetamol tablets should be done with caution.