磷脂存在下人参皂甙的含量测定

探讨了磷脂对人参皂甙含量测定的影响。实验结果表明：当以氯仿脱脂时,由于磷脂的增溶作用,增加了人参皂甙在非极性有机溶剂中的溶解度,造成含量测定结果偏低;从而建立了以大孔吸附树脂分出磷脂后进行比色测定的方法。平均回收率为１０１．３８％,ＲＳＤ为１．２２％。     

The Influence of Abrasive and Acidic Aggressions on the Surface Condition of Flowable Composite Resin

The aim of this in vitro study was to evaluate the effect of hydrochloric acid associated with the abrasive effect of toothbrushing on the surface condition of three flowable composite resins used for direct restoration. Seventy samples of each composite resin: Grandio Flow (VOCO, Germany)—group A, Filtek Ultimate Flow (3M-ESPE, MN, USA)—group B, G-aenial Flo X (GC Europe)—group C were prepared, submersed in hydrochloric acid 30% for 60 min and then submitted to simulated toothbrushing procedure using 5000 cycles with toothbrushes with medium and hard bristles, immediately after the chemical attack, after 30 min or without any chemical attack. The sample’s surface roughness was analyzed using a noncontact profilometer (Dektak XT, Bruker, USA). ANOVA and post hoc Bonferroni tests, with a p < 0.05, were used to analyze the values. Hydrochloric acid action for 60 min and six months of toothbrushing using toothbrushes having medium hardness or firm bristles affects the surface roughness of tested flowable composite resins. Toothbrushing with firm bristles immediately after acidic challenge determines increased surface roughness for two of the three flowable composite resins (Grandio Flow and Filtek Ultimate Flow). Toothbrushing with medium or firm bristles thirty minutes after the acidic aggression determine no effect on surface condition of flowable composite resins.     

AB-8树脂精制柴芩两解汤的工艺研究

目的确定AB-8树脂精制柴芩两解汤的最佳工艺。方法采用L9(34)正交设计,以HPLC法测定其中黄芩苷和栀子苷的吸附、解析率为指标,分别考察动态吸附中药液浓度、树脂量、流速对吸附的影响;以及解析液浓度、体积、流速3个因素对解析的影响。结果吸附药液浓度为0.15 g生药/mL,树脂用量为3倍药材量,速度10 mL/min;解析液为75%乙醇,10倍药材量,流速10 mL/mim,黄芩苷及栀子苷的解析率可达95%以上。结论AB-8树脂精制柴芩两解汤工艺简单、稳定、可控。      

不同粘结剂对瓷-牙本质粘结剪切强度的研究

目的：观察比较不同树脂粘结剂对IPS Empress 2全瓷基底粘结剪切强度的效果。方法：选择无龋坏的人磨牙24个,随机分为4组,每组6个。第1组用RelyX Veneer进行粘结。第2组用RelyX unicem进行粘结。第3组用RelyX ARC进行粘结。第4组用Variolink 2进行粘结。所有样本在37°C蒸馏水中储存24h后,进行测试,记录剪切强度值,用SPSS11.0对结果进行单因素方差分析,并在光学显微镜下观察粘结破坏情况。结果：RelyX Veneer、RelyX ARC、Variolink 2的剪切强度显著高于RelyX unicem的剪切强度（P〈0.05）,破坏界面多发生在牙本质与粘结剂之间。结论：RelyX Veneer、RelyX ARC、Variolink 2都可以用于IPS Empress 2全瓷系统的粘结。     

Crack-Resistant Amino Resin Flame-Retardant Coatings Using Waterborne Polyurethane as a Co-Binder Resin

Surface cracking is a major issue in amino resin-based flame-retardant coatings, which can be reduced by mixing flexible resins into the coatings. In this study, flexible waterborne polyurethane (WPU) was added into a melamine-modified, urea-formaldehyde, resin-based intumescent flame retardant (MUF-IFR) coating. A molecular chain of WPU was inserted into the MUF network and formed a WPU/MUF-semi-IPN structure. The cracking resistance of the coating was gradually enhanced with the increase in WPU content. When the WPU content exceeded 25% of the total resin, there were no cracks in the coatings after crack-resistance tests. The coatings before and after toughening showed good transparency on wood surfaces. The influence of WPU on char formation and flame retardant properties were explored by TGA, SEM, and cone calorimetry. The results showed that the decomposition of WPU occurred before char formation, which decreased the integrity of the coating and damaged the compactness of the char. Therefore, the addition of WPU reduced the expansion height and the barrier capacity of the char as well as the flame retardant properties of the coating. When the amount of WPU was 25% of the total resin, compared to the non-WPU coating, the average heat release rate in 300 s (AveHRR_300s) and the total heat release at 300 s (THR_300s) of the samples were increased by 45.8% and 35.7%, respectively. However, compared to the naked wood, the peak heat release rate (pHRR₁), AveHRR_300s, and THR_300s of the samples with the coating containing 25% WPU were decreased by 64.2%, 39.0%, and 39.7%, respectively. Therefore, the thermal stability of WPU affected char formation. The amount of WPU added should be chosen to be the amount that was added just before the coating cracked.     

An Evaluation of the Hydrolytic Stability of Selected Experimental Dental Matrices and Composites

Materials with potential use as dental restoration should be evaluated in an aggressive environment. Such accelerated aging is widely used in other industries and allows the assessment of service life. In the presented study, three neat resins (UDMA/Bis-GMA/TEGDMA 70/10/20 wt.%, UDMA/Bis-GMA/TEGDMA 40/40/20 wt.% and UDMA/Bis-EMA/TEGDMA 40/40/20 wt.%) and three composites based on these matrices were tested before and after aging protocols (I-7500 cycles, 5 °C and 55 °C, water and 7 days, 60 °C, 0.1 M NaOH; II-5 days, 55 °C, water and 7 days, 60 °C, 0.1 M NaOH). Flexural strength (FS), diametral tensile strength (DTS) and hardness (HV) were determined. Applied aging protocols resulted in a decrease in the value of the FS, DTS and HV. Larger changes were noticed for the neat resins. Materials in which the content of bis-GMA was lower or substituted by bis-EMA showed better resistance to degradation. The choice of mixtures with monomers characterized by lower sorption values may favorably affect hydrolytic stability. It was shown that for composites there was a drastic decrease in hardness, which suggests a more superficial effect of the used protocols. However, degradation of the surface layer can result in a growing problem over time given that the mastication processes are an inherent element in the oral environment.     

Resin Flow Analysis for the Foam Core Sandwich Spoiler by Vacuum-Assisted Resin Injection Process

This article presents the numerical analysis and experimental investigation for the manufacturing of a foam core sandwich spoiler by vacuum-assisted resin injection (VARI) process. To find an injection scheme that guarantees both a good impregnation of the preform and a filling time compatible with the process window, the finite element model (FEM) was applied to analyze the effect of different injection schemes on the resin flow front patterns. Based on the obtained results, two optimal injection schemes are selected to form the spoiler structure. The experimental results show that the best molding quality can be achieved from the thick-end injection with a thin-end exit scheme. The comparison between simulation and experimental results shows that the overall deviation of the numerical analysis on resin flow time is 15.9%.     

Resin infiltration of deproteinised natural occlusal subsurface lesions improves initial quality of fissure sealing

The aim of this ex vivo study was to evaluate the infiltration capability and rate of microleakage of a low-viscous resin infiltrant combined with a flowable composite resin (RI/CR) when used with deproteinised and etched occlusal subsurface lesions (International Caries Detection and Assessment System code 2). This combined treatment procedure was compared with the exclusive use of flowable composite resin (CR) for fissure sealing. Twenty premolars and 20 molars revealing non-cavitated occlusal carious lesions were randomly divided into two groups and were meticulously cleaned and deproteinised using NaOCl (2%). After etching with HCl (15%), 10 premolar and 10 molar lesions were infiltrated (Icon/DMG; rhodamine B isothiocyanate (RITC)-labelled) followed by fissure sealing (G-?nial Flo/GC; experimental group, RI/CR). In the control group (CR), the carious fissures were only sealed. Specimens were cut perpendicular to the occlusal surface and through the area of the highest demineralisation (DIAGNOdent pen, KaVo). Using confocal laser-scanning microscopy, the specimens were assessed with regard to the percentage of caries infiltration, marginal adaption and internal integrity. Within the CR group, the carious lesions were not infiltrated. Both premolar (57.9%± 23.1%) and molar lesions (35.3%± 22.1%) of the RI/CR group were uniformly infiltrated to a substantial extent, albeit with significant differences (P=0.034). Moreover, microleakage (n=1) and the occurrence of voids (n=2) were reduced in the RI/CR group compared with the CR group (5 and 17 specimens, respectively). The RI/CR approach increases the initial quality of fissure sealing and is recommended for the clinical control of occlusal caries.     

曲马多药树脂速释混悬剂的研制

为掩盖盐酸曲马多的苦味 ,并达到迅速镇痛的目的 ,利用盐酸曲马多与离子交换树脂结合制成药物树脂的制备方法 ,进行了曲马多药树脂速释混悬剂的研制实验。实验结果表明 ,该制备方法简单 ,研制出的曲马多药树脂速释混悬剂稳定、口味好、释放迅速     

ABS树脂的阻燃化研究：I.添加小分子阻燃剂

系统地研究了ＦＲ－ＴＮＸ、Ｓｂ２Ｏ３、Ｍｇ（ＯＨ）２、Ａｌ（ＯＨ）３等小分子阻燃剂对ＡＢＳ树脂的阻燃效果及其协同效应。结果表明，单一阻燃剂的作用不太明显；锑卤复配可取得较好的协同效应；通过测定冲击强度和拉伸性能，考察了阻燃剂对ＡＢＳ树脂的机械性能的影响，并通过ＤＭＡ进一步分析了阻燃剂与树脂的相容性；通过ＴＧＡ等热分析手段探讨了小分子阻燃剂在凝聚相的阻燃行为与作用机理。