Effects of moisture conditions of dental enamel surface on bond strength of brackets bonded with moisture-insensitive primer adhesive system

The purposes of this study were to evaluate the effects of different degrees of water contamination on the shear bond strength of orthodontic brackets bonded to dental enamel with a moisture-insensitive primer (MIP) adhesive system and to compare the modes of bracket/adhesive failure. A total of 68 human premolars were divided into four groups by primers and enamel surface conditions (desiccated, blot dry, and overwet). In group I, the hydrophobic Transbond XT primer adhesive system was used under desiccated conditions for bonding the brackets; in group II, the hydrophilic Transbond MIP adhesive system was used under desiccated conditions; in group III, the hydrophilic Transbond MIP adhesive system was used under blot dry conditions; and in group IV, the hydrophilic Transbond MIP adhesive system was used under overwet conditions. Shear bond strength was measured with a universal testing machine, and the mode of bracket/adhesive failure was determined according to the adhesive remnant index. The mean shear bond strengths were not significantly different among groups I, II, and III, and were higher than the clinically required range of 6 to 8 MPa. The mean shear bond strength achieved in group IV was significantly lower than that achieved in groups I, II, and III, and also lower than the clinically required values. Bond failure occurred at the enamel-adhesive interface more frequently in group IV than in groups I and III. To achieve clinically sufficient bond strengths with the hydrophilic MIP adhesive system, excess water should be blotted from the water-contaminated enamel surface.     

壳聚糖的改性及保湿性研究

目的：为了改善壳聚糖的水溶性,拓展其应用前景。方法：在壳聚糖6位羟基上进行羧甲基化,通过正交试验,对皂化温度、皂化时间以及醚化时间进行优化。以甘油、透明质酸、胶原蛋白为参照物,在一定相对湿度下考察了羧甲基壳聚糖保湿性能。结果：优化后的反应条件：皂化温度为45℃;皂化时间为150min;醚化时间为120min。结论：羧甲基壳聚糖保湿性最优,完全可以替代透明质酸,作为多种化妆品的保湿剂。     

不同温、湿度下多种透明敷贴潮气通透率的变化

目的：通过对目前临床导管护理常用的透明敷贴及传统敷料纱布进行潮气通透性的实验室研究与对比,寻求在不同的湿度下最佳的高潮气通透率贴膜,为临床的应用及研究提供理论依据。方法：取50ml塑料离心管内装20ml去离子水,分别用目前常用的医用贴膜（IV3000、3M HP TegadermTM、OPSITE FLEXIGRID 、3M TegadermTM）将管口封闭正置,敷料不与去离子水接触（模拟医用敷料与正常皮肤接触情况）,以及将管口封闭倒置（除12层普通纱布外）,敷料与含水表面接触（模拟医用敷料与出汗的皮肤或渗液的创面皮肤接触情况）,置于温度20℃、37℃的Rxz型智能人工气候箱中24小时,分别于实验前后称取离心管的重量,每组5个标本。观察不同湿度（湿度30％、60％、90％）条件下的水蒸发量,计算其潮气通透率（MTR）。结果：用12层普通纱布及IV3000、OPSITE FLEXIGRID 、3M HP TegadermTM、3M TegadermTM四种贴膜在模拟医用敷料与正常皮肤接触情况下,环境湿度为30％、60％、90％,其温度20℃、37℃时的潮气通透率显示总体为12层普通纱布的潮气通透性最佳,其次为IV3000、3M HP TegadermTM、OPSITE FLEXIGRID OPSITE FLEXIGRID 、3M TegadermTM四种贴膜,并随着环境相对湿度的升高其潮气通透率逐渐下降,不同敷料之间及不同湿度条件下各组的潮气通透率经统计学分析均有极显著差异（P＜0.01）;在高温（37℃）、高湿（90％）时,IV3000贴膜的潮气通透率明显优于12层的普通纱布,差异非常显著（P＜0.01）。各种反应性潮气通透率的性能IV3000贴膜为最佳,达到10.2～16.3倍,其次为3M HP TegadermTM达到2.6～9.6倍。结论：环境的湿度及温度对敷料（普通纱布及各种透明贴膜）的潮气通透性能有较大的影响。一般情况下,12层的普通纱布的透气、透湿性能为最佳,IV3000贴膜其潮气通透率与12层普通纱布较为接近,属于高潮气通透率的贴膜,具有一定的优越性,值得临床导管护理选择敷料时关注,其临床实际对导管相关感染的影响尚有待于多中心观察来进一步证实。     

Effect of Biocompost-Amendment on Degradation of Triazoles Fungicides in Soil

Soil amendments play an important role in management of pesticide residues. Present study reports the effect of biocompost-amendment on degradation of penconazole and propiconazole (triazole fungicides) in a sandy loam soil under flooded and nonflooded (60% water holding capacity) conditions. Penconazole degraded at faster rate than propiconazole. Both the fungicides were found to be more persistent in flooded soil than nonflooded soil, but application of biocompost at 2.5% and 5.0% levels enhanced their degradation under both moisture regimes.     

Importance of glassy-to-rubbery state transitions in moisture-protective polymer coatings

The aim of this study was to better understand the mechanisms governing water transport in polymeric film coatings used for moisture protection. Tablets containing garlic powder were coated with Methocel^® E5 (hydroxypropyl methylcellulose), Opadry^® AMB [poly(vinylalcohol)-based formulation] and Eudragit^® E PO [poly(methacrylate-methylmethacrylate)]. Their water content at different temperatures and relative humidities were determined. The polymers were characterized by X-ray powder diffraction and differential scanning calorimetry (DSC). The latter revealed significant physical changes in Opadry^® AMB during storage, while Eudragit^® E PO remained unchanged. For Opadry^® AMB, a strong dependence of the vapor permeability on the water content of the system was observed. The water uptake drastically increased with increasing relative humidity and storage temperature due to structural polymer changes (glassy-to-rubbery state transition). Linear relationships between the initial uptake rate and the relative humidity or temperature were established. Storage below critical threshold values of 66% RH (at room temperature) and 16 °C (at 75% RH) significantly reduced water imbibition. Opadry^® AMB-based film coatings undergo a glassy-to-rubbery state transition upon storage at room temperature and elevated relative humidity, resulting in significantly increased mobility of the polymer chains and, thus, increased water uptake rates.     

AOTF-近红外光谱技术测定前列欣胶囊中欧前胡素、水分、细菌含量的即时快速检测分析

目的:建立测定前列欣胶囊中欧前胡素、水分、细菌含量的即时快速检测分析方法。方法:采用声光可调滤光器-近红外(AOTF-NIR)光谱技术。检测器为InGaAs,测样方式为漫反射,光谱范围为1100～2200nm,波长增量为2.0nm,平均次数为300次。采用偏最小二乘法分别建立校正集样本中5个检测指标的NIR定量分析模型,并对验证集样本进行预测。采用TheUnscram-bler软件分析。结果:欧前胡素和水分含量模型的预测结果较好,NIR预测值与化学值之间的相关系数r分别为0.9993和0.9950,平均RSD为2.44%和1.07%;所建细菌梯度模型则可对不同范围内的细菌个数进行较准确预测,预测结果的平均RSD为6.61%和4.59%。结论:AOTF-NIR为前列欣胶囊的全面质量快速分析提供了一种新方法,而且为中成药固体制剂中水分的快速测定提供了借鉴,为中成药生产过程中细菌等微生物的在线检测做了有益的探索。     

Effect of water on deformation and bonding of pregelatinized starch compacts

This paper evaluates the tabletting process of pregelatinized starch with different moisture contents on the basis of the stress deformation curve. Simplification of the stress deformation curve enables the amount of elastically stored energy to be calculated. That stored energy, which is the driving force for relaxation of tablets, increases with compaction speed and decreases with increasing water activity of the material. This paper suggests a relation between absorbed water and stored energy. Interparticle bonding, however, also decreases with increasing amounts of adsorbed water. The decrease in stored energy with increasing water activity of the pregelatinized starch tends to produce stronger tablets at higher water activities, whereas the decrease of particle bonding with increasing water activity tends to produce weaker tablets at higher water activities. Given these two counteracting effects, the final tablet strength is a balance between viscoelasticity and bonding, resulting in a water activity where tablet strength has a maximum. In this case, the optimum water activity is about 0.70.     

A method for determining the heat transfer and water vapour permeability of patient support systems

The formation of pressure ulcers can be exacerbated by a breakdown in the integrity of the patient's skin caused by poor maintenance of the skin microclimate. Patient support systems (PSSs—specialised beds, mattresses, chairs, cushions and pads) play an important role in the dissipation of heat and moisture away from the skin/support interface which is necessary in order to maintain the physiological skin microclimate.

This paper reports a laboratory method and theory for the simultaneous measurement of the heat and water vapour dissipating properties of PSSs. The results demonstrate that the method is extremely selective, exhibiting very significant differences between the PSSs tested. It also shows that assessing PSS covers independently does not necessarily indicate the overall performance of the complete PSS.     

药用全蝎含水量、含盐量的测定

目的:对市售全蝎含水量、含盐量进行测定.方法:用烘干法测定全蝎含水量和银量法测定全蝎含盐量.结果:市售全蝎含水量、含盐量最高分别这40.16%、38.75%.结论:建议<中国药典>增加全蝎的含水量、含盐量限度标准,以确保全蝎的质量.     

临床急危重患者体重称量系统的设计研发

在医学临床急危重不易搬动的患者和血液透析治疗患者的体重称量对于身体内环境的管理非常重要，为解决临床这群特殊患者体重称量的难题，本人自行设计研究了适应于各种患者需要的系列体重称量装置。