Evaluation of radiation damage behavior in polyimide aerogel by infrared camera and photoacoustic spectroscopy

In this work, the optical absorption and thermal properties of polyimide aerogel have been investigated by Infrared Camera, ultraviolet–visible and photoacoustic spectroscopy under low energy proton irradiation. The characterization method of the infrared camera can obtain the optical absorption ratio, and meanwhile get the information of specific heat capacity. Moreover, it can acquire the nature information of damaged area rather than the overall performance. The results show an increase in optical absorption after proton irradiation, which is in good coincidence with Ultraviolet–visible spectroscopy analysis. And the specific heat capacity decreased linearly with proton fluences, which can be attributed to the irradiation damage and carbonization in polyimide aerogel. The Raman spectra suggested the cleavage of chemical bonds and carbonization in polyimide aerogel. This work provides the novel, non-destructive and sensitive methods to characterize irradiation damage of aerogel.     

Fabrication of exfoliated graphite reinforced silicone rubber composites - Mechanical,tribological and dielectric properties

The effect of exfoliated graphite (EG) on the mechanical, tribological and dielectric properties of the silicone rubber (QM) composites has been systematically investigated and analysed. Morphological analysis of the composites helps to understand the interfacial interaction between the filler and the rubber matrix as well as wear mechanism respectively. An enhancement in the mechanical, tribological and dielectric properties was observed with an increase in filler loading and better performance was observed at 7 phr of filler loading. The improvement in performance is attributed to the better interaction between the QM chains and the EG layers as evident from the AFM and TEM analysis. It is also evident from the Kraus plot which supports the reinforcing effect of EG in QM matrix.     

Effect of moisture content on the heat-sealing property of starch films from different botanical sources

In this study, we investigated the differences in the crystallinity of starch films (mung bean, water chestnut, sweet potato, and cassava starches) with different moisture contents stored in different humidity conditions (11%, 22%, 33%, 43%, 54%, 75%, and 84%) and evaluated their thermal adhesion and sealing properties. X-ray diffraction analysis revealed an association between the degree of crystallinity and the moisture content in starch films: crystallinity decreased with an increase in the moisture content. Field Emission Scanning Electron Microscopy (FE-SEM) analysis showed that films with low moisture content failed to completely adhere, but films with a high moisture content and lower crystallinity showed good adherence, with two films perfectly adhered at the same temperature because water molecules acted as a mobility enhancer. The peeling test demonstrated the failure modes of the heat-bound films. The cassava starch film, which had a low amylose content and crystallinity, showed better adhesion compared to other starch films.     

Anisotropic charge carrier transport of optoelectronic functional selenium-containing organic semiconductor materials

Organic semiconductors (OSCs) materials are currently under intense investigation because of their potential applications such as organic field-effect transistors, organic photovoltaic devices, and organic light-emitting diodes. Inspired by the selenization strategy can promote anisotropic charge carrier migration, and selenium-containing compounds have been proved to be promising materials as OSCs both for hole and electron transfer. Herein, we now explore the anisotropic transport properties of the series of selenium-containing compounds. For the compound containing Se Se bond, the Se Se bond will break when attaching an electron, thus those compounds cannot act as n-type OSCs. About the different isomer compounds with conjugated structure, the charge transfer will be affected by the stacking of the conjugated structures. The analysis of chemical structure and charge transfer property indicates that Se-containing materials are promising high-performance OSCs and might be used as p-type, n-type, or ambipolar OSCs. Furthermore, the symmetry of the selenium-containing OSCs will affect the type of OSCs. In addition, there is no direct relationship between the R groups with their performance, whether it or not as p-type OSCs or n-types. This work demonstrates the relationship between the optoelectronic function and structure of selenium-containing OSCs materials and hence paves the way to design and improve optoelectronic function of OSCs materials.     

基于正电荷和光热协同效应的新型半导体聚合物纳米抗菌材料

由于抗生素的不当使用和细菌多药耐药的出现, 迫切需要开发新的抗菌剂. 本文制备了具有光热转换性能的正电荷半导体高分子材料及具有协同抗菌活性的半导体聚合物纳米粒子(SP-PPh₃ NPs). SP-PPh₃ NPs的光热转化效率为43.8%. 带正电荷的SP-PPh₃ NPs可以附着在细菌上, 有助于将热量有效传递给细菌. 在热和正电荷的协同作用下, SP-PPh₃ NPs对革兰氏阴性大肠杆菌(E. coli)和革兰氏阳性金黄色葡萄球菌(S. aureus)均具有抗菌活性, 其对二者的体外抑菌率分别为99.9%和98.6%. 此外, SP-PPh₃ NPs具有良好的生物相容性, 对小鼠的主要器官几乎无副作用. 对细菌感染的小鼠皮肤伤口用SP-PPh₃ NPs治疗12 d后, 伤口可以很好地愈合.     

双金属磷化物和杂原子共修饰碳材料的制备及电催化性能

以高含氮量的苯胺五聚体二羧酸为配体, 在预氧化的泡沫镍上通过溶剂热反应合成了Fe, Co金属有机框架材料Fe/Co-MOF, 再以Fe/Co-MOF为金属源和碳源, 经磷化后制备出一种新型的双金属(Fe, Co)和杂原子(N, P)共掺杂的碳材料Fe/Co/P-NPs. 通过扫描电子显微镜和高分辨透射电子显微镜表征发现, Fe/Co/P-NPs由纳米粒子和纳米片组成, 并且形成Fe₂P和Co₂P两种晶体. 电化学测试结果表明, Fe/Co/P-NPs在析氢、 析氧及水电解中表现出了优异的多功能催化活性. 在1 mol/L KOH中, Fe/Co/P-NPs在10和100 mA/cm ²电流密度时的析氧过电位分别为270和300 mV, 均小于其它对比材料, 优于负载在泡沫镍上的RuO₂. 作为水电解双功能催化剂, Fe/Co/P-NPs仅需1.48 V的电位即可获得10 mA/cm ²的电流密度.     

Theoretical investigation of the molecular structure,vibrational spectra,and molecular docking of tramadol using density functional theory

The optimized molecular structures, harmonic vibrational wavenumbers, and the corresponding vibrational assignments of (1S,2S)-tramadol and (1R,2R)-tramadol are computationally examined using the B3LYP density functional theory method together with the standard 6–311++G(d,p) and def2-TVZP basis sets. The optimized structures show that phenolic rings of both 1R,2R and 1S,2S tramadol adopt planar geometry, which are slightly distorted due to the substitution at the meta-position; and the six-membered cyclohexane adopts a slightly distorted chair conformation. The 1S,2S enantiomer is energetically more favorable than 1R,2R with the energy differences of 1.32 and 1.03 kcal/mol obtained at B3LYP/6–311++G(d,p) and B3LYP/Def2-TVZP levels, respectively. The analysis of the binding pocket in the silico molecular docking with the m-opioid receptor shows that it originated two clusters with the 1S,2S enantiomer and one cluster with the 1R,2R enantiomer of tramadol. The results point to a more stable complex of the m-opioid receptor with the 1R,2R enantiomer of tramadol.     

Photocontrolled Release of the Anticancer Drug Chlorambucil with Caged Harmonic Nanoparticles

While chemotherapy is one of the most used treatments in oncology, the systemic administration of chemotherapeutics generally results in undesired damages to healthy tissues and cells, side effects such as severe nausea and leukopenia, and reduced efficacy due to multidrug resistance and poor target accessibility. The limitations of conventional chemotherapy formulation have prompted the development of alternative nanomaterials-based strategies to achieve targeted and stimuli sensitive payload delivery to reach optimal local drug concentration at tumor sites. In this study, the anticancer drug chlorambucil (Clb) was conjugated to the surface of silica coated lithium niobate (LNO) harmonic nanoparticles (HNPs) using a photocaging tether based on coumarin-4-yl methyl derivative. Upon laser pulsed femtosecond irradiation at 790 nm, the second harmonic emission from the metal oxide core induced the efficient release of Clb, with concomitant contribution from the nonlinear absorption of the coumarin (CM)-based moiety.     

Effect of Oxygen on the Oxidation of Methane with Hydrogen Peroxide to Methanol in the Presence of Glutathione-Stabilized Gold Nanoclusters

Kinetics and Catalysis - The catalytic activity of glutathione-stabilized gold thiolate nanoclusters (1–2 nm) in the oxidation of methane with H2O2 and air oxygen in aqueous medium at...     

An Aptamer-Nanotrain Assembled from Six-Letter DNA Delivers Doxorubicin Selectively to Liver Cancer Cells

Expanding the number of nucleotides in DNA increases the information density of functional DNA molecules, creating nanoassemblies that cannot be invaded by natural DNA/RNA in complex biological systems. Here, we show how six-letter GACTZP DNA contributes this property in two parts of a nanoassembly: 1) in an aptamer evolved from a six-letter DNA library to selectively bind liver cancer cells; and 2) in a six-letter self-assembling GACTZP nanotrain that carries the drug doxorubicin. The aptamer-nanotrain assembly, charged with doxorubicin, selectively kills liver cancer cells in culture, as the selectivity of the aptamer binding directs doxorubicin into the aptamer-targeted cells. The assembly does not kill untransformed cells that the aptamer does not bind. This architecture, built with an expanded genetic alphabet, is reminiscent of antibodies conjugated to drugs, which presumably act by this mechanism as well, but with the antibody replaced by an aptamer.