半导体TiO2的光催化性能及其应用

TiO₂作为一种优秀的光催化材料，其在环境保护等领域的应用研究十分活跃，主要是在废水处理、空气净化、癌症治疗以及杀菌消毒等方面。介绍了新颖的光诱导超亲水性及其应用。     

Leveraging Bioinspired Structural Constraints for Tunable and Programmable Snapping Dynamics in High-Speed Soft Actuators

Creating high-speed soft actuators will have broad engineering and technological applications. Snapping provides a power-amplified mechanism to achieve rapid movements in soft actuators that typically show slow movements. However, precise control of snapping dynamics (e.g., speed and direction of launching or jumping) remains a daunting challenge. Here, a bioinspired design principle is presented that harnesses a reconfigurable constraint structure integrated into a photoactive liquid crystal elastomer actuator to enable tunable and programmable control over its snapping dynamics. By reconfiguring constrained fin-array-shaped structure, the snapping dynamics of the structured actuator, such as launching or jumping angle and height, motion speed, and release force can be on-demand tuned, thus enabling controllable catapult motion and programmable jumping. Moreover, the structured actuators exhibit a unique combination of ultrafast moving speed (up to 2.5 m s⁻¹ in launching and 0.22 m s⁻¹ in jumping), powerful ejection (long ejection distance of ≈20 cm, 35 mg ball), and high jumping height (≈8 cm, 40 times body lengths), which few other soft actuators can achieve. This study provides a new universal design paradigm for realizing controllable rapid movements and high-power motions in soft matter, which are useful for building high-performance soft robotics and actuation devices.     

钒离子注入改进Pilkington自洁玻璃材料的亲水性研究

ActivTM玻璃是Pilkington公司推出的具有优异光催化性能和光致亲水性的自洁防雾玻璃,是近几年发展起来的新型建筑材料.其表面的TiO2薄膜的光催化性和亲水性性能都很稳定,但亲水性的光致响应时间较长.采用钒离子注入工艺对ActivTM玻璃进行掺杂改性,研究了钒离子在不同注入能量、浓度和后处理退火温度的条件下对玻璃光致亲水性的影响.研究表明,钒离子注入能够有效改善玻璃表面TiO2薄膜的亲水性,而且,较高钒离子注入能量(90keV)和掺杂浓度(6×10 16ions/cm2),玻璃光致亲水性要好,在紫外光照射1h后接触角均能小于7°,退火温度取500℃为宜.     

聚丙烯酰胺凝胶的光反应合成及性能研究

以丙烯酰胺为单体,分别以N,N′-亚甲基双丙烯酰胺和过硫酸胺为交联剂、引发剂,利用紫外光引发,分别在聚合物基底(PET,PS薄膜)及硅片上制备了聚丙烯酰胺(PAAm)凝胶.研究表明,凝胶的成胶时间、表面形貌、稳定性、溶胀率等对基底的依赖性很强:在亲水性基底上凝胶成胶时间较疏水性基底短;溶胀率不仅与UV光照时间、交联剂的含量等因素有关,而且还与基底的性质有关,在亲水性基底上形成的凝胶平衡溶胀率小于在疏水性基底上制备的凝胶.     

氧化钒薄膜太赫兹波段频率特性研究

利用直流对靶磁控溅射镀膜法,在Si衬底上制备出在太赫兹（THz）波段具有开关性能的氧化钒（VOx）薄膜。用X射线光电子能谱（XPS）、扫描电子显微镜（SEM）方法对VOx薄膜的组份和形貌进行表征。利用THz时域频谱系统（THz-TDS）对VOx薄膜的光致相变性能进行测试。实验表明,VOx薄膜在波长532 nm连续激光照...     

卤氧化铋光催化剂的改性研究与应用

能源和环境作为当今世界两大热点问题,备受人们的关注。针对这两大问题的解决,光催化技术深受研究人员的青睐。其中,卤氧化铋(BiOX,X=Cl、Br、I)因其特殊的层状结构、适宜的带隙宽度、优异的光电性能,在光催化领域脱颖而出。本文围绕卤氧化铋的结构及性能,介绍了对其改性的研究,通过形貌调控、半导体复合、离子掺杂、表面改性等方法,以提高卤氧化铋及其复合物的活性位点暴露量、光生载流子的传输与分离效率及光吸收性能。同时列举了改性后的卤氧化铋在能源与环境领域的应用,并对不同改性手段的局限性进行了探讨,以期为卤氧化铋的应用提供参考。     

纳米TiO_2/β-CD光催化纸耐老化性能的研究

在紫外老化箱中对原纸表面涂覆不同比例的纳米TiO2/β-环糊精(β-CD)涂料的涂布纸进行抗紫外光返黄实验,并利用SEM和FT-IR等手段分析光照前后的纸张涂层结构和涂料成分。结果表明:经紫外光照30h后,涂布纸表面涂层稍有结块,而涂料成分没有发生明显变化;光照前后涂覆不同比例的纳米TiO2/β-CD涂料的涂布纸物理性能均优于涂布原纸,其中用含量为2%纳米TiO2和1%β-CD(均相对于涂料的质量分数)的涂料涂覆的涂布纸的物理性能和光学性能最好;用含量为3%纳米TiO2和1%β-CD的涂料涂覆的涂布纸不仅不能提高纸页的抗返黄能力,反而会加速其返黄进程。     

Structural insights into peptide self-assembly using photo-induced crosslinking experiments and discontinuous molecular dynamics

Determining the structure of the (oligomeric) intermediates that form during the self-assembly of amyloidogenic peptides is challenging because of their heterogeneous and dynamic nature. Thus, there is need for methodology to analyze the underlying molecular structure of these transient species. In this work, a combination of fluorescence quenching, photo-induced crosslinking (PIC) and molecular dynamics simulation was used to study the assembly of a synthetic amyloid-forming peptide, Aβ_16-22. A PIC amino acid containing a trifluormethyldiazirine (TFMD) group—Fmoc(TFMD)Phe—was incorporated into the sequence (Aβ*_16–22). Electrospray ionization ion-mobility spectrometry mass-spectrometry (ESI-IMS-MS) analysis of the PIC products confirmed that Aβ*_16–22 forms assemblies with the monomers arranged as anti-parallel, in-register β-strands at all time points during the aggregation assay. The assembly process was also monitored separately using fluorescence quenching to profile the fibril assembly reaction. The molecular picture resulting from discontinuous molecule dynamics simulations showed that Aβ_16-22 assembles through a single-step nucleation into a β-sheet fibril in agreement with these experimental observations. This study provides detailed structural insights into the Aβ_16-22 self-assembly processes, paving the way to explore the self-assembly mechanism of larger, more complex peptides, including those whose aggregation is responsible for human disease.     

Reduction-oxidation photocycle dynamics of flavins in starch films

The blue-light photo-reduction (conversion of oxidized flavin quinone via flavin semiquinone to fully reduced flavin hydroquinone) and dark re-oxidation of the flavins riboflavin and lumiflavin in starch (α-amylose) films was studied by absorption and luminescence spectroscopy. Blue-light photo-excitation caused an absorption, fluorescence, and phosphorescence decrease which recovered in the dark. The photo-reduction dark-oxidation cycle could be repeated. The efficiency of photo-reduction decreased with exposed excitation energy, and the speed of re-oxidation in the dark slowed down with time after excitation. The absorption did not fully recover. The fluorescence efficiency after a long time of storage in the dark increased beyond the initial flavin quinone fluorescence efficiency. Flavin photo-excitation is thought to cause starch-flavin restructuring (static fluorescence quenching center formation), enabling enhanced photo-induced starch to flavin electron transfer with subsequent flavin reduction and starch oxidation. In the dark, after light switch-off, thermal reversion of flavin reduction and starch oxidation occurred.