排序方式: 共有8条查询结果,搜索用时 15 毫秒
1
1.
重庆市市委会办公大楼旧址前有一组露天存放的清代砂岩石狮子,表面覆盖着黑色硬壳状物质, 发生大面积脱落,起翘和卷曲。为了揭示黑色硬壳状结构组成,研究其形成过程及对文物产生的影响,利用环境扫描电子显微镜(SEM),X-射线衍射仪(XRD),X-射线荧光光谱仪(XRF),傅里叶变换红外光谱仪(FTIR)和X-射线光电子能谱(XPS)对黑色硬壳及文物表层砂岩样品进行了检测分析研究。结果发现:黑色硬壳断面Mapping元素分布图显示其分为底漆层,中间层和表层,系石刻早期封护层的老化产物;中间层含有立德粉(硫化锌和硫酸钡),黑色外观源于表层中含铅颜料(铅白)变色形成黑色硫化铅及树脂碳化所致;红外光谱与光电子能谱显示出黑色硬壳中含有强的羟基(-OH)特征峰,说明封护层中有机物老化后形成了大量羟基,从而增强了自身亲水性,造成易吸水溶胀与干燥收缩情况,导致大面积脱落,起翘和卷曲现象;黑色硬壳起翘和卷曲部位与下层石刻表面之间形成了易于积水的微空隙,能够聚集雨水中的有害物质,造成石刻表层岩石发生腐蚀,例如黑色硬壳背面及下层岩石表面中高含量硬石膏(CaSO4),经生水化作用后转化为石膏(CaSO4·2H2O),发生体积膨胀造成岩石表面松动和酥粉。因此,当露天文物表面上封护层已老化时,及时地进行清除是十分必要的。 相似文献
2.
3.
4.
5.
1引言α-氰基丙烯酸乙酯作为一类新型医用粘合剂,具有粘合此血作用快,组织反应轻、可被机体吸收等诸多优点作为医用材料,对α-氨基丙烯酸乙酯的性能指标应有严格要求,因而合成工艺校为复杂.为了提高产品质量,降低成本在生产过程中必须对a-氰基丙烯酸乙酯进行定量分析.关于α-氰基丙烯酸乙酯的定量分析.只有文献提及用元素分析法显然该法不适宜生产过程的质量控制、由于α-氰基丙烯酸乙酯容易发生聚合,色谱分析存在困难.因此我们建立了α-氰基丙烯酸乙酯分光光度法的快速定量分析.2实验部分Ztl仪器与试剂岛津UV.2… 相似文献
6.
用水热法合成出一种新的一维链状簇合物{[Ni(enMe)2][SiW12O40]}[Ni(enMe)2(H2O)2]2·3H2O, 并对其进行了元素分析、IR谱、TGA及X射线单晶衍射等系列表征. 该晶体属于单斜晶系, 空间群C2/c, a=1.2656 nm, b=2.20656(4) nm, c=2.26763(4) nm, β=92.078°, V=6.32852(16) nm3, Z=4, Dc=3.801 g/cm3, μ=2.271 mm-1, F(000)=6512, R1=0.0549, wR2=0.1087. 在该化合物中, 具有α-Keggin结构的聚阴离子簇[SiW12O40]6-之间通过配位阳离子[Ni(enMe)2]2+桥连成一维无限链状结构, 另一种配位阳离子[Ni(enMe)2(H2O)2]2+和水分子填充在结构中, 通过分子间的氢键作用将该化合物拓展为三维网状结构. 相似文献
7.
酒石酸掺杂聚苯胺纳米纤维的制备及性能研究 总被引:1,自引:0,他引:1
在酒石酸体系中研究不同合成方法、酒石酸浓度、反应温度、反应时间等因素对制备聚苯胺纳米纤维的影响,通过扫描电镜(SEM)、红外光谱(FT-IR)及紫外光谱(UV-Vis)测试技术对产物进行了表征,测定了不同方法制备产物在N-甲基吡咯烷酮中溶解性能,并采用电化学测试技术研究了产物的防腐性能。结果表明,直接混合法是一种简便高效的聚合方法,可制备高品质聚苯胺;最佳合成条件为酒石酸0.1mol/L、温度20℃、反应时间24h。直接混合法制备产物,其溶解性与缓慢滴加法产物相近,高于界面聚合法产物,为4.7g/L,防腐蚀效率优于缓慢滴加法和界面聚合法产物,达到87.79%。 相似文献
8.
Near equilibrium dynamics and one-dimensional spatial–temporal structures of polar active liquid crystals 下载免费PDF全文
We systematically explore near equilibrium, flow-driven, and flow-activity coupled dynamics of polar active liquid crystals using a continuum model. Firstly, we re-derive the hydrodynamic model to ensure the thermodynamic laws are obeyed and elastic stresses and forces are consistently accounted. We then carry out a linear stability analysis about constant steady states to study near equilibrium dynamics around the steady states, revealing long-wave instability inherent in this model system and how active parameters in the model affect the instability. We then study model predictions for onedimensional(1D) spatial–temporal structures of active liquid crystals in a channel subject to physical boundary conditions.We discuss the model prediction in two selected regimes, one is the viscous stress dominated regime, also known as the flow-driven regime, while the other is the full regime, in which all active mechanisms are included. In the viscous stress dominated regime, the polarity vector is driven by the prescribed flow field. Dynamics depend sensitively on the physical boundary condition and the type of the driven flow field. Bulk-dominated temporal periodic states and spatially homogeneous states are possible under weak anchoring conditions while spatially inhomogeneous states exist under strong anchoring conditions. In the full model, flow-orientation interaction generates a host of planar as well as out-of-plane spatial–temporal structures related to the spontaneous flows due to the molecular self-propelled motion. These results provide contact with the recent literature on active nematic suspensions. In addition, symmetry breaking patterns emerge as the additional active viscous stress due to the polarity vector is included in the force balance. The inertia effect is found to limit the long-time survival of spatial structures to those with small wave numbers, i.e., an asymptotic coarsening to long wave structures. A rich set of mechanisms for generating and limiting the flow structures as well as the spatial–temporal structures predicted by the model are displayed. 相似文献
1