Solid Polymer Electrolytes from Copolymers Based on Vinyl Dimethyl Phosphonate and Vinylidene Fluoride

Solid polymer electrolytes are prepared by mixing various amounts of lithium bis(trifluoromethanesulfonyl)imide with poly(vinylidene fluoride‐co‐vinyl dimethyl phosphonate) statistical copolymers with different compositions. Such copolymers are obtained by conventional radical copolymerization of vinylidene fluoride (VDF) with vinyl dimethyl phosphonate (VDMP) initiated by peroxides. A morphological study of the obtained solid polymer electrolytes (SPEs) shows that only samples prepared from the copolymer with the lower amount of VDMP (16 mol%) result in the formation of homogeneous electrolytes while aggregates of lithium salts are observed for the other copolymers. The best ionic conductivity values are accordingly observed for the copolymers with the lower VDMP amount and are reaching 5 × 10^?3 mS cm^?1 at 100 °C. The dependence of the ionic conductivity versus temperature suggests that the ionic conductivity is controlled by the motion of polymer segments. Indeed, the ionic conductivity can be increased by adding a small amount of trimethylphosphate plasticizer and can reach 1.9 × 10^?2 mS cm^?1 at 20 °C. Finally, the prepared SPEs exhibit a high electrochemical stability and a good resistance to flame because of the presence of fire‐retardant phosphate groups in their structure.     

Comparison of the effect and safety of Er:YAG laser combined with fluoride and methylene blue-photodynamic therapy on caries prevention

目的 比较Er:YAG激光-氟化钠联合法与亚甲基蓝-光动力疗法（MB-PDT）的防龋效果及安全性。方法 建立28只大鼠龋齿模型,随机分成7组：不同功率密度的光动力疗法（PDT）组、激光+氟化钠联合组、激光组、氟化钠组和0.9%生理盐水组。分光光度法检测变异链球菌生长抑制情况;激光荧光诊断仪（LF）检测龋损脱矿程度;组织病理观察牙髓及颊黏膜损伤状况。结果 PDT组与激光+氟化钠联合组光密度值明显低于其他处理组（P<0.05）;不同处理方法均可使LF值上升,出现不同程度的脱矿;组织病理学观察,70 mw·cm^-2的联合组和Er:YAG激光组存在牙髓及颊黏膜损伤。结论 相同参数下,联合组与PDT均有良好的杀菌效果,但PDT不良反应少、损伤小,是一种高效且安全的防龋手段。     

Determination of Impact Damage in CFRP via PVDF Signal Analysis with Support Vector Machine

Carbon fiber reinforced plastics (CFRPs) have high specific stiffness and strength, but they are vulnerable to transverse loading, especially low-velocity impact loadings. The impact damage may cause serious strength reduction in CFRP structure, but the damage in a CFRP is mainly internal and microscopic, that it is barely visible. Therefore, this study proposes a method of determining impact damage in CFRP via poly(vinylidene fluoride) (PVDF) sensor, which is convenient and has high mechanical and electrical performance. In total, 114 drop impact tests were performed to investigate on impact responses and PVDF signals due to impacts. The test results were analyzed to determine the damage of specimens and signal features, which are relevant to failure mechanisms were extracted from PVDF signals by means of discrete wavelet transform (DWT). Support vector machine (SVM) was used for optimal classification of damage state, and the model using radial basis function (RBF) kernel showed the best performance. The model was validated through a 4-fold cross-validation, and the accuracy was reported to be 92.30%. In conclusion, impact damage in CFRP structures can be effectively determined using the spectral analysis and the machine learning-based classification on PVDF signals.     

氟化钠甘油过敏1例

近年来药物过敏引起的口腔黏膜溃疡越来越多,但氟化钠甘油过敏引起的溃疡却极少见。山东大学千佛山校区医院遇到氟化钠甘油过敏1例,氟化钠甘油治疗后患者口腔黏膜充血水肿明显,颊、腭黏膜有大量红色粟粒状颗粒,3 h后出现吞咽困难,但无呼吸困难,次日出现口腔黏膜大面积溃疡。治疗7 d后患者痊愈,氟化钠敏感试验结果为阳性。