Mg∶Er∶LiNbO_3晶体的生长和抗光损伤性能

在1%(摩尔分数,下同)Er∶LiNbO3中分别掺入2%,4%,6%的MgO,用提拉法生长Mg∶Er∶LiNbO3晶体。用X射线荧光光谱仪 测试Mg∶Er∶LiNbO3晶体中Mg和Er的分凝系数。采用m线法研究Mg∶Er∶LiNbO3晶体波导基片光损伤阈值。结果表明:随着Mg2+浓 度的增加,Er3+在LiNbO3中的分凝系数下降。6%Mg∶l%Er∶LiNbO3晶体波导基片光损伤阈值比l%Er∶LiNbO3基片提高2个数量级以 上。采用锂空位模型讨论Mg∶Er∶LiNbO3晶体光损伤阈值提高的机理。     

Characterization of fibrillar collagen types using multi-dimensional multiphoton laser scanning microscopy

In dermal photodamage the ratio of the collagen types III to I changes. This makes the investigation of the fibrillar collagen type characteristics interesting for skin research. In this study collagen types were characterized using 5-dimensional multiphoton laser scanning microscopy (5D-IVT) that can be applied in vivo. Second harmonic generation (SHG) signals and fluorescence lifetimes of the collagen autofluorescence were analysed. Collagen type I generates a higher SHG intensity and a longer fluorescence lifetime compared to collagen type III. Thus, the SHG intensity decrease found in photodamaged skin might be explained by the increase in collagen type III. Calculating the in vivo relevant increase of collagen type III gives a negligible difference in fluorescence lifetime not qualifying this method for the determination of collagen type changes in dermal photodamage in vivo in human skin. However, for pathologies that exhibit higher differences in collagen types 5D-IVT analysis might be a suitable method.     

Update on ultraviolet A and B radiation generated by the sun and artificial lamps and their effects on skin

Solar radiation, especially ultraviolet A (UVA) and ultraviolet B (UVB), can cause damage to the human body, and exposure to the radiation may vary according to the geographical location, time of year and other factors. The effects of UVA and UVB radiation on organisms range from erythema formation, through tanning and reduced synthesis of macromolecules such as collagen and elastin, to carcinogenic DNA mutations. Some studies suggest that, in addition to the radiation emitted by the sun, artificial sources of radiation, such as commercial lamps, can also generate small amounts of UVA and UVB radiation. Depending on the source intensity and on the distance from the source, this radiation can be harmful to photosensitive individuals. In healthy subjects, the evidence on the danger of this radiation is still far from conclusive.     

物理性因素对头发的影响

头发自长出头皮就受到各种物理性和化学性因素的影响。影响头发的物理性因素主要有日光、梳理、吹风以及一些机械性损害等。掌握一定的科学美发知识,可避免造成头发的物理性和化学性损伤。     

高掺锌富锂铌酸锂体抗光损伤能力的研究

以Czochralski法生长Zn(6mol%)：LiNbO3,Li/Nb=0.94,0.97,1,1.02。测试晶体的光损伤阈值。采用质子交换法制作高掺锌富锂铌酸锂晶体光波导,研究了它们的抗光损伤能力。     

激光对DNA作用的损伤效应

用Ｎｄ（３＋）：ＹＡＧＱ开关二倍频激光分别照射λ－ＤＮＡ／ＨｉｎｄⅢ，鱼－ＤＮＡ，小牛－ＤＮＡ和酵母－ＲＮＡ，在相同的激光剂量条件下，观察不同激光照射时间对ＤＮＡ的作用。测定了ＤＮＡ的ＵＶ谱，讨论了激光辐照导致ＤＮＡ链断裂的分子机制．     

Destruction of polymer growth substrates for cell cultures in two-photon microscopy

The choice of the growth substrate for cell cultures used in fluorescence microscopy is guided by several factors including the type of cells studied and the type of microscopy used. Usually, cells can be cultured on either polymer or glass substrates. One type of polymer, termed Aclar, presents several attractive features: the adhesive properties are better than those of glass, the optical properties are comparable to those of glass, it is biochemically inert, unbreakable, flexible and has a high surface tension, convenient for seeding cells on the cover slip. However, here we show that when imaging with two-photon microscopy, which is based on a femtosecond pulsed laser source, local damage of the Aclar substrate occurs, starting at an average intensity of 10⁵ W cm⁻² at the focal point and for exposure times insufficient to cause cell damage. This leads to the appearance of gas bubbles on cultures plated on Aclar cover slips, which perturb the imaging. By contrast, this phenomenon does not occur on borosilicate cover slips, probably because of their different physical (thermal conductivity, absorbance, melting point) and material homogeneity properties. Thus, for cell culture applications using pulsed lasers with high intensities, the use of glass is preferable to Aclar. The results also reveal that substrates can be more susceptible to thermal damage than the cells themselves.     

光甘草定包合物对中波紫外线诱导小鼠皮肤光损伤的保护作用

目的 以环糊精(cyclodextrin,CD)为载体制备光甘草定(glabridin,GL)包合物,探讨光甘草定环糊精包合物(GL/CD)对中波紫外线(middlewave ultraviolet radiation,UVB)诱导的小鼠皮肤光损伤的保护作用。方法 制备GL/CD,进行包封率和透射电子显微镜(transmission electron microscope,TEM)表征分析,通过UVB照射小鼠皮肤光损伤模型,在小鼠背部皮肤涂抹不同浓度的GL及GL/CD,通过测试经皮水分散失(trans-epidermal water loss,TEWL)、皮肤组织生化指标、免疫组化染色研究其对光损伤后皮肤屏障保护的效果。结果 GL/CD的包封率为84.21%±1.36%,平均粒径为(533.1±42.8) nm,Zeta电位为(-30.24±1.54) mV,表明包合物在水体系中分散为纳米颗粒且稳定性良好。TEM结果显示GL/CD分散在水体系后主要呈现为球形胶束状态。小鼠皮肤黑色素染色结果显示GL/CD对黑色素生成的抑制效果优于GL。TEWL测试结果显示GL/CD显著降低小鼠经皮失水率,且效果比GL好。苏木精-伊红染色结果显示GL经CD包合之后能显著增强其抗炎作用,降低UVB照射引起的表皮增厚和炎症浸润。酶联免疫吸附实验结果显示GL经CD包合之后能显著提升抗氧化酶包括超氧化物歧化酶和过氧化氢酶的生物合成,降低活性氧及促炎细胞因子包括白细胞介素1、白细胞介素6和肿瘤坏死因子α在体内的表达水平。结论 GL经过CD的包合,有效提升了其在UVB诱导的皮肤损伤方面的保护作用。