Investigation on the Evolution of Nano-Scale Defects of CL-20 Crystals under Thermal Treatment by Wide/Small-Angle X-ray Scattering

Nano-scale crystal defects extremely affect the security and reliability of the explosive charges of weapons. In order to understand the evolution of nano-scale defects of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane (CL-20) explosive crystals under thermal treatments, the specific surface, volume fraction and size distribution of the nano-scale defects were studied by using Wide Angle X-ray Scattering (WAXS) and Small Angle X-ray Scattering (SAXS) during the temperature range from 30 °C to 200 °C. The results showed that the number and size of the pores in CL-20 powder did not change significantly during the heating process before phase transformation (30–160 °C). At 170 °C, CL-20 began to convert from ε- to γ- phase, and the specific surface and volume fraction of the nano-scale defects increased significantly. Further investigation of the pore size distribution showed that the number of pores with a small size (radius 9–21 nm) changed particularly significantly, resulting from the cracking of the CL-20 crystal powder during phase transition. At 200 °C, the phase transition was completed and γ-CL-20 was created, and the small-sized pores gradually grew into medium-sized (radius 21–52 nm) pores over time when the temperature was fixed at 200 °C.     

Wettability and Surface Roughness of Parylene C on Three-Dimensional-Printed Photopolymers

The use of poly-(para-chloro-xylylene) (Parylene C) in microelectromechanical systems and medical devices has increased rapidly. However, little research has been conducted on the wettability and surface roughness of Parylene C after being soaked in solutions. In this study, the contact angle and surface roughness (arithmetic average of roughness) of Parylene C on three-dimensional (3D)-printed photopolymer in 10% sodium hydroxide, 10% ammonium hydroxide, and 100% phosphate-buffered saline (PBS) solutions were investigated using a commercial contact angle measurement system and laser confocal microscope, respectively. The collected data indicated that 10% ammonium hydroxide had no major effect on the contact angle of Parylene C on a substrate, with a Shore A hardness of 50. However, 10% sodium hydroxide, 10% ammonium hydroxide, and 100% PBS considerably affected the contact angle of Parylene C on a substrate with a Shore A hardness of 85. Substrates with Parylene C coating exhibited lower surface roughness than uncoated substrates. The substrates coated with Parylene C that were soaked in 10% ammonium hydroxide exhibited high surface roughness. The aforementioned results indicate that 3D-printed photopolymers coated with Parylene C can offer potential benefits when used in biocompatible devices.     

The Effect of Dentifrice on Micro-Hardness,Surface Gloss,and Micro-Roughness of Nano Filled Conventional and Bulk-Fill Polymer Composite—A Micro Indentation and Profilometric Study

The aim of the present study was to evaluate the effect of brushing with two whitening dentifrices (Colgate Optic White (COW) and Colgate Optic White Charcoal (COC)) on surface gloss, micro-roughness, and micro-hardness of nanostructured hybrid conventional (Z350) and bulk-fill (Tetric N Ceram bulk-fill) polymer composite. In total, 96 disk samples using two nano-hybrid composite polymers (Z350 and Tetric N Ceram Bulk-fill) were prepared. All specimens were exposed to two different dentifrices (COW and COC), resulting in four main subgroups in the study. Specimens were assessed for surface gloss, micro-roughness (Ra), and micro-hardness using standardized methodology. Means and standard deviations of properties compared using paired t-test, one-way and two-way ANOVA, and post hoc test. The presence of dentifrices did not show any significant difference in micro-hardness values of Z350 (p > 0.05), whereas micro-hardness of bulk-fill composite significantly reduced on dentifrices exposure (p ≤ 0.05). Bulk-fill polymer composite showed significant reduction in gloss after dentifrice exposure (p < 0.05), however, Z350 showed no significant loss of gloss due to dentifrices (p > 0.05). A significant increase in Ra was observed for both resin materials after exposure to dentifrices (COC and COW). Conventional resin composite (Z350) showed comparable surface hardness and gloss before and after dentifrice exposure, however, micro-roughness increased significantly due to dentifrice exposure. Bulk-fill resin (Tetric N Ceram) showed significant loss of micro-hardness and gloss and increase in micro-roughness on dentifrice exposure. Conventional nano-hybrid composite polymer showed better durability in resisting loss of surface properties compared to bulk-fill resin polymer in the present experiment.     

基于Box-Behnken响应面设计优选中药复方便乃通的提取工艺

[目的] 利用Box-Behnken响应面设计法优化中药复方便乃通（BNT）的提取工艺。[方法] 基于单因素实验优选BNT提取工艺的影响因素及其范围,运用Box-Behnken响应面设计法构建三因素三水平实验设计方案,以番泻苷B、番泻苷A及橙皮苷的含量作为响应指标优选最佳提取工艺条件,并进行工艺验证。[结果] 中药复方BNT的最佳提取工艺条件为料液比1∶8,回流时间30 min,提取次数2次。[结论] 利用Box-Behnken响应面设计法优化中药复方BNT提取工艺方法稳定,可为BNT提取工艺提供参考。     

鼻咽癌放疗性角膜损伤的跟踪研究

目的:探讨鼻咽癌(NPC)放射治疗眼部并发症。方法:对 213 例 NPC 初程放疗患者进行跟踪观察。放疗前、放疗中及放疗后作视功能(包括远视力、裂隙灯活体显微镜、眼底、自动电脑视野及视诱发电位)检查和角膜荧光素染色。结果:发生角膜损伤 19 例,占 8.9 %(19/213)。I～Ⅱ期6 例,Ⅲ期 8 例,Ⅳ期 5 例。全部发病患者均无角膜刺激症状,放疗后 10mo 内,角膜病变消退,但知觉仍较对侧眼明显减退;20mo 后尚未恢复正常。未发现晶状体混浊的患者。结论:NPC 放疗性角膜损伤与鼻咽癌临床分期及照射剂量无密切关系(P>0.05),可能主要与角膜感觉神经损伤导致眼表疾病密切相关;不排除患者不同个体对辐射的敏感差异性。     

Study on Milling Force and Surface Quality during Slot Milling of Plain-Woven CFRP with PCD Tools

Carbon-fiber-reinforced polymers (CFRPs) have been widely used in many industrial fields, such as automobile, aerospace and so on, because of their excellent mechanical properties. However, due to their anisotropy and inhomogeneity, machining CFRPs is a great challenge. In this paper, the slot milling of a plain-woven CFRP with PCD tools is carried out, and the effects of cutting parameters and tool rake angle on cutting force and surface roughness are studied. The results show that the 4° rake angle PCD tool has smaller cutting force than the 0° rake angle PCD tool, but the effect of rake angle on surface roughness is not significant. The concept of equivalent cutting area is introduced to study the variation law of cutting force and surface roughness. It is found that the cutting force and surface roughness increase with the increase in equivalent cutting area, and decrease with the decrease in equivalent cutting area. The removal mechanism of surface materials under different equivalent cutting areas is different, which leads to the difference in surface roughness. Finally, the causes of delamination on the top layer after milling are explained.     

Artificial Weathering of Contact-Charred Wood—The Effect of Modification Duration,Wood Species and Material Density

A relevant issue with charred exteriors is the inconsistency of the result, which makes service life predictions complicated. Contact charring enables the creation of a very evenly modified surface with accurate control of temperature and modification time, but the weathering properties are questionable. This paper evaluated the effect of the modification time relative to char layer and transition zone thickness, wood species and material density in an artificial weathering test. The results revealed higher color stability in connection to longer modification time, but also an increase in the cracked surface area. Cracking was heavily dependent on the modification regime and increased with increasing char and transition zone thicknesses. Dense spruce had the highest color stability with the most severe modification regime, but char layer thickness varied more than on other wood types. Furthermore, species-dependent cracking patterns affected the final result as the small-scale flaking experienced by birch increased the washing off of char. It is likely an even higher modification temperature with a shorter modification time is needed to produce sufficient weathering resistance suitable for exterior uses.     

Quality and Quantity Assessment of the Water Repellent Properties of Functional Clothing Materials after Washing

The aim of the research was to evaluate the changes in the surface properties of five functional clothing materials with water-repellent finishes (including PFC-free finish) after 1, 5, and 10 washes with three detergents. A new approach to the interpretation of the water-repellent properties of textile materials is presented, based on two techniques, i.e., the spray test method and contact angle measurements. The results showed that washing materials with hydrophobic finishes can cause significant changes in their properties, which are mainly dependent on the composition and structure of the material, as well as the type of hydrophobic finish. The PFC-free finish is the least resistant to washing. For all materials with PFC finishes, the water repellency depends on the fluorine content on the surface and fabric topography. It was also found that increasing washing frequency resulted in a gradual decrease in water repellency. The loss of water repellency below an acceptable level (Grade 3) occurred after the fifth washing for all materials. Significant differences in the interpretation of the results of the spray test and contact angle measurements were observed. Using these methods separately provides information on the changes in the surface properties of the tested materials; however, their parallel application allows for obtaining complementary data, which is important for the proper interpretation of results.     

上海市浦东新区自动售水机卫生状况及影响因素分析

[目的]了解自动售水机选址与外表卫生状况,为改善自动售水机卫生现状提出建议。[方法]以上海市浦东新区辖区内所有的自动售水机为对象,随机抽取236台对其选址、遮雨棚设置、机器外表整洁及完整与否、出水口防护门、出水管口及取水凹口周壁等内容开展卫生学调查。[结果]调查结果表明,17．37％的自动售水机设置点周围10m范围内存在污染源;11．44％的自动售水机设置点周围地面排水不畅,有积水;2．54％的自动售水机未安装防护门和8．47％的自动售水机防护门已损坏不能正常使用;30．93％的自动售水机器外表存在各种污迹,同时有2．12％的受调查机器外壳已破损;受调查自动售水机的出水管口、取水凹口顶壁、内侧壁的细菌总数、霉菌、大肠菌群的检出率分别为78．81％、39．41％、48．30％;75．85％、81．78％、90．68％和21．19％、5．93％、15．25％。同时,保持自动售水机周边环境整洁、设置取水凹口防护门并保持正常运作、出水管外套有套管对减少或减轻上述部位的污染有着显著的意义。[结论]自动售水机经营单位应加强设备管理,注意维护设备的外表整洁,定期对取水凹口周壁、出水管口进行清洗、消毒;同时,要注意保持设备周边环境的整洁,并应在设备上加装取水凹口防护门、出水管套管等装置,维护其正常运作和洁净。     

Box-behnken响应面法优化紫红生肌软膏的醇提工艺

目的 优选紫红生肌软膏的醇提工艺参数,为紫红生肌软膏的新药开发提供依据.方法 以栀子苷、连翘酯苷A、羟基红花黄色素A为评价指标,在单因素试验的基础上,以乙醇浓度、加醇量、提取时间为考察因素,采用Box-behnken响应面法设计试验,采用层次分析法-熵权法组合赋权确定各指标权重系数并计算综合评分,从而优化紫红生肌软膏醇...