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101.
It has often been observed anecdotally and implied through experimentation that acrylic emulsion paintings accumulate and entrain soils over time due to the inherent mechanical softness in artist's acrylic paint films, through the presence of hydrophilic film components, and by virtue of the ubiquitous presence of surfactant moieties on these film surfaces once they dry. In the present study, it has been this last effect that we have sought to describe more fully in terms of surfactant responsiveness to both temperature and relative humidity (RH). Surfactant hydration and dehydration under varying temperature and RH conditions affects the ultimate partitioning of the surfactant at the paint–air interface, as well as the inherent size, aggregation tendencies, and solubility of surfactant in the bulk paint materials which contain components that are highly responsive to changes in temperature and RH (e.g. polyacrylic or polymaleic anhydride-type dispersal materials). In this work, analytical techniques including three-dimensional microscopy and quartz crystal microbalance with dissipation were used to add to and reinforce current understanding of the physical and mechanical changes to acrylic paint films with temperature and RH. The migration of surfactant at the film surface was studied using desorption electrospray ionization-mass spectrometry and attenuated total reflectance Fourier transform infrared microscopy. 相似文献
102.
Mu-zi Li Jin-rui Wang Hong Liu Xia Wang Kang Gan Xiu-ju Liu De-li Niu Xiao-qing Song 《Journal of Zhejiang University. Science. B》2016,17(9):703-711
Objective
This study explored the effects of different light curing modes and ethanol-wet bonding on dentin bonding strength and durability.Methods
A total of 54 molars were randomly divided into three groups: Single Bond 2, Gluma Comfort Bond, and N-Bond. Based on the three light-curing modes and presence or absence of ethanol pretreatment, the samples were assigned to six subgroups: high-light mode, ethanol pretreatment+high-light mode, soft-start mode, ethanol pretreatment+soft-start mode, standard mode, and ethanol pretreatment+standard mode. All samples were bonded with resin based on the experimental groups. After 24 h and 6 months of water storage, a universal testing machine was used to measure microtensile bond strength. Scanning electron microscopy (SEM) was applied to observe mixed layer morphology.Results
The 24-h and 6-month microtensile bond strengths of the ethanol pretreatment groups were significantly higher than those of the non-ethanol pretreatment groups at the same light modes (P<0.05). With or without ethanol pretreatment, the microtensile bond strengths of the high-light modes were significantly lower than those of the soft-start modes and standard modes (P<0.05). The microtensile bond strengths of samples from the 6-month water storage group significantly decreased compared with those of samples from the 24-h water storage group (P<0.05). The soft-start groups and standard groups formed better mixed layers than the high-light mode groups, whereas the ethanol pretreatment groups formed more uniform mixed layers than those without ethanol pretreatment.Conclusions
Ethanol-wet bonding technique, soft-start, and standard modes could improve dentin bonding properties.103.
采用液态镓作为离子源的FIB系统在材料科学研究领域可以起非常重要的作用。离子束聚焦于样品表面，在不同大小、束流及通入不同辅助气体的情况下，可分别实现图形刻蚀、绝缘和金属膜的沉淀，扫描离子成像等功能。该系统有三大用途：形貌观察，分辨率高达5nm；微刻蚀以及微沉淀。本文介绍了FIB技术的应用。 相似文献
104.
Dan LIU Song LI Ejazul ISLAM Jun-ren CHEN Jia-sen WU Zheng-qian YE Dan-li PENG Wen-bo YAN Kou-ping LU 《Journal of Zhejiang University. Science. B》2015,16(2):123-130
目的:探索毛竹在修复铅污染土壤的植物修复潜力。创新点:使用了毛竹作为一种全新的植物修复材料进行研究。得到了毛竹幼苗在铅胁迫下的生长与生理反应情况,不同植物组织对铅的吸收与积累情况,铅胁迫下毛竹幼苗表层与细胞超微结构的特征。方法:根系形态分析(图3)、植物重金属含量分析(表1)、扫描电镜分析(图4)和透射电镜分析(图5)。结论:各组织部位铅浓度的值揭示了,毛竹是一个很好的固定铅污染土壤的植物材料;但是由于毛竹茎的高生物量,也可以作为铅污染土壤的植物修复材料。在0~200μmol/L铅处理下,毛竹的生物量与根系形态没有显著性差异,生长正常未出现中毒症状。通过扫描电镜观察铅胁迫导致叶片的气孔减少,根与茎内含物增多。通过透射电镜观察高浓度的铅胁迫导致部分细胞内部叶绿体变形、内质网消失、细胞核与核仁缩小和类囊体膜消失。尽管超微结构观察到细胞内部的损害,但是未出现视觉的毒性症状。毛竹铅的高耐性与茎的高生物量,提供了毛竹作为材料修复土壤重金属铅更大的可能性。 相似文献
105.
The concept and existence of learning styles has been fraught with controversy, and recent studies have thrown their existence into doubt. Yet, many students still hold to the conventional wisdom that learning styles are legitimate, and may adapt their outside of class study strategies to match these learning styles. Thus, this study aims to assess if undergraduate anatomy students are more likely to utilize study strategies that align with their hypothetical learning styles (using the VARK analysis from Fleming and Mills, 1992 , Improve Acad. 11:137–155) and, if so, does this alignment correlate with their outcome in an anatomy course. Relatedly, this study examines whether students’ VARK learning styles are correlated with course outcomes regardless of the students’ study strategies, and whether any study strategies are correlated with course outcomes, regardless of student-specific VARK results. A total of 426 anatomy students from the 2015 and 2016 Fall semesters completed a study strategies survey and an online VARK questionnaire. Results demonstrated that most students did not report study strategies that correlated with their VARK assessment, and that student performance in anatomy was not correlated with their score in any VARK categories. Rather, some specific study strategies (irrespective of VARK results), such as use of the virtual microscope, were found to be positively correlated with final class grade. However, the alignment of these study strategies with VARK results had no correlation with anatomy course outcomes. Thus, this research provides further evidence that the conventional wisdom about learning styles should be rejected by educators and students alike. Anat Sci Educ. © 2018 American Association of Anatomists. 相似文献
106.
引言(1)历史背景和目的：此处微小晶体指尺寸小于1μm,不宜用X射线单晶体衍射分析方法测定结构的晶体。电子晶体学是借助电子射线与晶体的相互作用研究晶体结构的科学。20世纪70年代初期报道了能直接观测晶体中原子团的高分辨电子显微 相似文献
107.
108.
我们用兔抗人α-actinin(α-辅肌动蛋白)抗血清和羊抗兔IgG-胶体金复合物作为标记物,在由Lowicryl K4M包埋的组织超薄切片上定位Z带蛋白α-actinin。在大负荷斜蹲后48小时从6名男性受试者(年龄为22—22岁)的两侧腿股外肌中取得活检样品,并在运动后不同时刻及活检取样前对随机确定的每一受试者的一条腿进行针刺或静力牵张,另一侧腿作对照。结果发现,针刺或静力牵张腿Z带特异性标记密度比其对照腿高。此外,针刺或静力牵张还能使Z带发生超微结果的变化率分别减少36％和22％,并使显著变化的比例减少,轻度变化的比例增加。以上观察结果揭示了针刺或静力牵张能抑制由于α-actinin的解聚或降解引起的Z带超微结构变化过程,或者通过加速α-actinin的聚合或合成而促进Z带超微结构的恢复。 相似文献
109.
基于原子力显微镜的沥青微观结构观察与表征(英文) 总被引：1，自引：0，他引：1
利用原子力显微镜进行沥青微观结构的观察与表征.选用针入度分别为50#和70#的2种基质沥青及一种SBS改性沥青,分析沥青种类及短期老化对微观结构的影响.基于对微观特性的认识,讨论了沥青微观结构与自愈性能之间的联系.研究表明:对于不同沥青,其微观结构形态相差较大,且结构随老化而变化的规律也各不相同.初步推断观测到的蜂状结构是一种结晶体,其分子组成与已有研究观测到的"桥接"自愈现象关系密切.相关结论为沥青微观结构机理和自愈性能研究提供了新的思路. 相似文献
110.
采用多层膜理论的菲涅尔矩阵系数法导出光子隧道信息的计算公式,并对电子隧道信息进行了光学方法的推导,得到了与量子力学中电子隧道效应一致的公式.此外,比较了光子隧道效应与电子隧道效应的异同. 相似文献