紫外辐照对溶胶-凝胶光学薄膜性能的影响

采用溶胶-凝胶技术,使用旋涂方法在K9玻璃和单晶硅片上制备各种光学薄膜,并用紫外光源作为高能光子源辐照溶胶-凝胶光学薄膜。使用扫描电镜(SEM)、原子力显微镜(AFM)、椭偏仪、铅笔硬度仪等测量和分析薄膜的特性。用输出波长1 064 nm、脉宽15 ns电光调Q激光系统测试薄膜的激光损伤阈值。结果表明,紫外光辐照可提高薄膜折射率和机械性能。采用紫外预处理还能将节瘤缺陷转换成孔洞缺陷,从而有效提高薄膜的激光损伤阈值,其中,单层ZrO2薄膜的激光损伤阈值达到50.6 J/cm2(1 064 nm,1 ns)。与当前流行的激光预处理技术相比,紫外预处理的设备简单、易于操作。溶胶-凝胶多层膜经紫外光处理后,有效提高了多层膜膜层的均匀性。     

Hydrolytic degradation of poly(L-lactic acid): Combined effects of UV treatment and crystallization

Amorphous and crystallized poly(L -lactic acid) (PLLA) films were prepared and the hydrolytic degradation of the ultraviolet (UV)-treated and UV-nontreated films was investigated. This study reveals that the combination of UV and thermal treatments can produce the PLLA materials having different hydrolytic degradation profiles and that the UV-irradiation in the environment will affect the design of recycling process for PLLA articles. In an early stage, the degrees of hydrolytic degradation monitored by weight loss (W_loss), number-average molecular weight (M _n), and melting temperature (T _m) were higher for the UV-treated films than for the UV-nontreated films. In a late stage, the trend traced by W_loss was reversed, and the difference in the degrees of hydrolytic degradation between the UV-treated and UV-nontreated films monitored by M _n and T _m became smaller, with the exception of the degrees of hydrolytic degradation of the amorphous films traced by T _m. Also, in the early stage, the degrees of hydrolytic degradation monitored by W_loss and M _n were higher for the crystallized films than for the amorphous films. In the late stage, this trend was reversed, with the exception of the degrees of hydrolytic degradation of the UV-treated films monitored by M _n. The main factors that determined the W_loss and T _m were the molecular weight and initial crystallinty but not the molecular structures such as terminal CC double bonds and crosslinks. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Use of titanium dioxide (TiO2) photocatalysts as alternative means for Listeria monocytogenes biofilm disinfection in food processing

The aim of this work was to study the photocatalytic activity of titanium dioxide (TiO₂) against Listeria monocytogenes bacterial biofilm. Different TiO₂ nanostructured thin films were deposited on surfaces such as stainless steel and glass using the doctor-blade technique. All the surfaces were placed in test tubes containing Brain Heart (BH) broth and inoculated with L. monocytogenes. Test tubes were then incubated for 10 days at 16 °C in order to allow biofilm development. After biofilm formation, the surfaces were illuminated by ultraviolet A light (UVA; wavelength of 315-400 nm). The quantification of biofilms was performed using the bead vortexing method, followed by agar plating and/or by conductance measurements (via the metabolic activity of biofilm cells). The presence of the TiO₂ nanoparticles resulted in a fastest log-reduction of bacterial biofilm compared to the control test. The biofilm of L. monocytogenes for the glass nanoparticle 1 (glass surface modified by 16% w/v TiO₂) was found to have decreased by 3 log CFU/cm² after 90 min irradiation by UVA. The use of TiO₂ nanostructured photocatalysts as alternative means of disinfecting contaminated surfaces presents an intriguing case, which by further development may provide potent disinfecting solutions. Surface modification using nanostructured titania and UV irradiation is an innovative combination to enhance food safety and economizing time and money.     

沥青的老化机理与性能研究

介绍了沥青的老化机理。介绍通过室内模拟加速老化试验(短期热氧老化试验、长期热氧老化试验和长期光热老化试验)和对沥青的四组分分析,研究了沥青在拌和、铺筑和使用过程中光氧、热氧老化机理。以及沥青老化表征的一些方法。在老化过程中沥青的芳香分含量均显著减少,沥青质的含量均明显增加,饱和分只有少量的挥发衰减;在短期热氧老化和长期光氧老化试验中胶质含量均降低,但在长期热氧老化中胶质含量增加。     

紫外辐射改性聚乙烯膜的亲水性研究

以低密度聚乙烯(LDPE)膜为基体,通过紫外辐射方法接枝丙烯酸(AA),制得不同接枝率的LDPE-g-AA亲水膜;利用红外光谱和扫描电子显微镜分析膜接枝前后组成和形貌的变化,并通过测试与水接触角、沉降时间和吸水率研究接枝后聚乙烯膜的亲水性.红外谱图表明,辐射接枝后的聚乙烯膜表面引入了大量羧基,并且羧基的量随着接枝率的增大而增加.扫描电镜照片显示,接枝后膜表面出现明显的颗粒状物质,证明AA接枝到了聚乙烯膜表面.当LDPE-g-AA接枝率大于10%时接枝聚乙烯膜表面与水接触角由原来的89°降低到30°,沉降时间由原来的无穷大降低到11s,并且随着接枝率的继续增大,接触角与沉降时间趋于稳定;随着接枝率的增大,接枝后聚乙烯薄膜的吸水率增大.     

高海拔地区紫外辐射对硅橡胶复合绝缘子老化的影响

随着我国西部大开发以及全国范围内特高压工程的开展,硅橡胶复合绝缘子在高海拔地区得到了越来越广泛的应用,针对高海拔地区紫外辐射环境下复合绝缘子老化问题的研究也日益迫切。针对高海拔地区目照中的紫外辐射特征,本文分别采用UV-A、UV-B和UV-C三种紫外光源模拟各种典型的大气紫外辐射环境,对硅橡胶复合绝缘子进行5000h的紫外辐射,总辐射量可达36～54kJ／Cm^2,相当于高原地区5年左右的紫外辐射量,然后采用静态接触角法测量紫外辐射对硅橡胶绝缘子表面憎水性的影响,探讨了高海拔地区复合绝缘子的紫外老化过程与特征。研究结果表明：经过UV-A、UV-B、UV-C紫外辐射后,硅橡胶绝缘子均发生了一定程度的褪色现象,但并未影响材料的绝缘性能。UV-C紫外线对硅橡胶绝缘子长时间辐射后,试样硬度变大,柔顺性降低,表面静态接触角下降,憎水性部分丧失;UV-A和UV-B紫外线对绝缘子表面的硬度和憎水性影响不大．     

Collagen immobilization on poly(ethylene terephthalate) and polyurethane films after UV functionalization

An attractive alternative method to add new functionalities such as biocompatibility due to the micro- and nanoscaled modification of surfaces is offered by UV-modified polymers. The aim of this study was to evaluate the effect of the UV light functionalization on two polymers, poly(ethylene terephthalate) (PET) and polyurethane (PU) films, by means of atomic force microscopy (AFM), Fourier transform infrared–attenuated total reflectance (FTIR–ATR), and contact angle measurements. Thus, the UV-irradiation activates the polymers surface by breaking some chemical bonds and generation of new functional groups on the surface. This process can be controlled by the irradiation time. The topography provides the formation of superposed ‘nap’ and ‘wall-type’ structures on both untreated and treated samples. The surface parameters were found to depend on the polymer films before and after irradiation. The immobilization of collagen on PET surface was confirmed by X-ray photoelectron spectroscopy measurements and for PU surface was proved by FTIR–ATR. First technique suggests an increase of the nitrogen content at longer UV exposure time, and the second one reveals the appearance of the protein Amide I band. Supplementary, AFM measurements clearly revealed the presence of collagen attached on the polymer surface. Thus, these new UV-irradiated polymers are promising materials in our further attempts to obtain new biofunctionalized surfaces.     

UV-/thermal processing of sol-gel-derived lead-magnesium-niobium titanate thin films

This work aimed to describe the sol-gel synthesis and preparation of a near-morphotropic phase boundary lead-magnesium-niobium titanate (PMNT) material system, and to investigate the influences of room-temperature-UV-irradiation and rapid thermal annealing (RTA) processes on the properties of its thin films. It was postulated that the use of UV-irradiation prior to thermal processing could play a role in the generation of a structural difference that would manifest itself via the formation of a higher film thickness, which was more pronounced at higher RTA temperatures The PMNT thin film system described here (particularly those annealed at higher temperatures) appeared to be potentially suitable for ultrahigh-value-capacitor applications; the unexposed film annealed at 750 °C exhibited the highest high k value (1425) with a strongly pronounced perovskite phase (97%).     

预光照聚四氟乙烯薄膜表面的无光引发剂气相光接枝聚合

研究了聚四氟乙烯（ＰＴＦＥ）薄膜的非极性表面光接枝改性，以赋予其在面一定的极性，改善表面的亲水性。采用预光照、不加光引发剂，用紫外光直接引发ＰＴＦＥ薄膜表面的丙烯酸接枝。改性后薄膜表面的水接触角由９８°降至６５°，染色程度明显提高。研究了反应条件对接枝结果的影响，并通过ＥＳＣＡ等分析手段，探讨了接枝反应机理。预先照可活化ＰＴＦＥ膜表面，使聚四氟乙烯的Ｃ－Ｆ键断裂产生自由基。光引发剂二苯甲酮不能引发ＰＴＦＥ膜，而能引发丙烯酸，便之一生均聚物，不加二苯甲酮可减小接枝阻力。     

狗及大鼠精巢细胞的PNA切除修复能力与其核内非组蛋白含量的关系

在狗和大鼠精巢细胞中,以初级精母细胞的核内非组蛋白(NHP)含量最多,经UV照后,其DNA切除修复能力也最高;精原细胞核内NHP含量次之,在大鼠中见到其切除修复能力明显比初级精母细胞低,而在狗中只见其平均修复能力略低于初级精母细胞,尚未得统计学显著性;圆形精子细胞核内NHP含量更少,它们与精子一样都没有切除修复能力。还发现狗和大鼠精巢精子可据碱性甲苯胺兰0染色情况分为两类:一类核可被染色,表明还残留少量NHP;另一类不被染色,表明已无NHP。狗射出精子的核不含NHP。