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991.
Anton Muravev Ayrat Yakupov Tatiana Gerasimova Ramil Nugmanov Ekaterina Trushina Olga Babaeva Guliya Nizameeva Viktor Syakaev Sergey Katsyuba Sofiya Selektor Svetlana Solovieva Igor Antipin 《International journal of molecular sciences》2021,22(7)
Understanding the interaction of ions with organic receptors in confined space is of fundamental importance and could advance nanoelectronics and sensor design. In this work, metal ion complexation of conformationally varied thiacalix[4]monocrowns bearing lower-rim hydroxy (type I), dodecyloxy (type II), or methoxy (type III) fragments was evaluated. At the liquid–liquid interface, alkylated thiacalixcrowns-5(6) selectively extract alkali metal ions according to the induced-fit concept, whereas crown-4 receptors were ineffective due to distortion of the crown-ether cavity, as predicted by quantum-chemical calculations. In type-I ligands, alkali-metal ion extraction by the solvent-accessible crown-ether cavity was prevented, which resulted in competitive Ag+ extraction by sulfide bridges. Surprisingly, amphiphilic type-I/II conjugates moderately extracted other metal ions, which was attributed to calixarene aggregation in salt aqueous phase and supported by dynamic light scattering measurements. Cation–monolayer interactions at the air–water interface were monitored by surface pressure/potential measurements and UV/visible reflection–absorption spectroscopy. Topology-varied selectivity was evidenced, towards Sr2+ (crown-4), K+ (crown-5), and Ag+ (crown-6) in type-I receptors and Na+ (crown-4), Ca2+ (crown-5), and Cs+ (crown-6) in type-II receptors. Nuclear magnetic resonance and electronic absorption spectroscopy revealed exocyclic coordination in type-I ligands and cation–π interactions in type-II ligands. 相似文献
992.
Ramesh Ade S. Sathish Kumar S. Valanarasu S. Saravana Kumar S. Sasikumar V. Ganesh Yugandhar Bitla H. Algarni I.S. Yahia 《Ceramics International》2021,47(17):24031-24038
We report the effect of Ti-doping on structural, morphological, photoluminescence, optical and photoconductive properties of ZnO thin films. Pure and Ti(1, 3 and 5%)-doped ZnO thin films are deposited by the successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction analysis revealed the single-phase hexagonal wurtzite ZnO structure of all the films. Scanning electron microscope images suggest the formation of rod shaped particles in Ti-doped ZnO thin films. Photoluminescence spectra of all the films show emission peaks centered at 398 nm, 413 nm, 438 nm, 477 nm and 522 nm wavelengths. Optical properties support the semiconducting nature of all the films. The optical bandgap values are estimated to be 3.29 eV, 3.26 eV, 3.19 eV and 3.23 eV for ZnO, ZnO:Ti(1%), ZnO:Ti(3%) and ZnO:Ti(5%) thin films, respectively. Photoconductivity study indicates that ZnO:Ti(3%) thin film exhibits high responsivity, external quantum efficiency and detectivity of 0.30 AW-1, 97% and 5.49 × 1010 Jones, respectively, among all the films. The enhanced photoconductivity of Ti-doped ZnO thin films make them useful for optoelectronic applications. 相似文献
993.
Carolina Roxo Weronika Kotkowiak Anna Pasternak 《International journal of molecular sciences》2021,22(9)
G-quadruplexes (G4s) are non-canonical structures formed by guanine-rich sequences of DNA or RNA that have attracted increased attention as anticancer agents. This systematic study aimed to investigate the anticancer potential of five G4-forming, sequence-related DNA molecules in terms of their thermodynamic and structural properties, biostability and cellular uptake. The antiproliferative studies revealed that less thermodynamically stable G4s with three G-tetrads in the core and longer loops are more predisposed to effectively inhibit cancer cell growth. By contrast, highly structured G4s with an extended core containing four G-tetrads and longer loops are characterized by more efficient cellular uptake and improved biostability. Various analyses have indicated that the G4 structural elements are intrinsic to the biological activity of these molecules. Importantly, the structural requirements are different for efficient cancer cell line inhibition and favorable G4 cellular uptake. Thus, the ultimate antiproliferative potential of G4s is a net result of the specific balance among the structural features that are favorable for efficient uptake and those that increase the inhibitory activity of the studied molecules. Understanding the G4 structural features and their role in the biological activity of G-rich molecules might facilitate the development of novel, more potent G4-based therapeutics with unprecedented anticancer properties. 相似文献
994.
Mengqing Jiang Yihua Yin Weiquan Cai Jingli Zhang Lihong Fan Ying Yi Yue Dai Ting Zhou Jinsheng Liu 《应用聚合物科学杂志》2021,138(30):50731
To improve photostability and enhance utilization rate and reduce pest resistance, a new strategy based on the combination of photodynamic insecticide action and stimulus-responsive polymer micelles is developed. 4-(phenylazo)benzoic acid (PBA)-modified poly(ethylene glycol) monomethyl ether (mPEG) conjugate is prepared by the esterification reaction of mPEG and PBA, and followed by self-assembly in aqueous solution to obtain polymeric nanoparticles. TEM shows that the nanoparticles have a core-shell structure and an average diameter of 78 nm. DLS shows that the nanoparticles are stability in water solution but can change their structure in response to UV light and/or esterase stimulation. The photodegradation of Protoporphyrin IX (PpIX) encapsulated in the nanoparticles can be effectively inhibited because of aggregation-caused quenching effect, whose maximum photodegradation rate is about 20.54% after 8 h exposure to daylight compared with the complete photodegradation of free PpIX. UV light and/or esterase stimulus can trigger PpIX release and result in a high photodynamic activity. Compared with free PpIX, the PpIX-loaded nanoparticles show a higher phototoxicity to insect cells and the daylight pretreatment has little influence on the phototoxicity. 相似文献
995.
996.
997.
Anyamanee Chaiprasongsuk Zorica Janjetovic Tae-Kang Kim Cynthia J. Schwartz Robert C. Tuckey Edith K. Y. Tang Chander Raman Uraiwan Panich Andrzej T. Slominski 《International journal of molecular sciences》2020,21(24)
Lumisterol (L3) is a stereoisomer of 7-dehydrocholesterol and is produced through the photochemical transformation of 7-dehydrocholesteol induced by high doses of UVB. L3 is enzymatically hydroxylated by CYP11A1, producing 20(OH)L3, 22(OH)L3, 20,22(OH)2L3, and 24(OH)L3. Hydroxylumisterols function as reverse agonists of the retinoic acid-related orphan receptors α and γ (RORα/γ) and can interact with the non-genomic binding site of the vitamin D receptor (VDR). These intracellular receptors are mediators of photoprotection and anti-inflammatory activity. In this study, we show that L3-hydroxyderivatives significantly increase the expression of VDR at the mRNA and protein levels in keratinocytes, both non-irradiated and after UVB irradiation. L3-hydroxyderivatives also altered mRNA and protein levels for RORα/γ in non-irradiated cells, while the expression was significantly decreased in UVB-irradiated cells. In UVB-irradiated keratinocytes, L3-hydroxyderivatives inhibited nuclear translocation of NFκB p65 by enhancing levels of IκBα in the cytosol. This anti-inflammatory activity mediated by L3-hydroxyderivatives through suppression of NFκB signaling resulted in the inhibition of the expression of UVB-induced inflammatory cytokines, including IL-17, IFN-γ, and TNF-α. The L3-hydroxyderivatives promoted differentiation of UVB-irradiated keratinocytes as determined from upregulation of the expression at the mRNA of involucrin (IVL), filaggrine (FLG), and keratin 14 (KRT14), downregulation of transglutaminase 1 (TGM1), keratins including KRT1, and KRT10, and stimulation of ILV expression at the protein level. We conclude that CYP11A1-derived hydroxylumisterols are promising photoprotective agents capable of suppressing UVB-induced inflammatory responses and restoring epidermal function through targeting the VDR and RORs. 相似文献
998.
Lakshmikandhan Thatchanamurthy Sethuraman Krishnamoorthy Chandramohan Ayyavu 《Polymer-Plastics Technology and Engineering》2016,55(12):1211-1219
In the present work, 3-glycidyloxypropyltrimethoxysilane functionalized alumina (F-Al2O3) was prepared and the formation of chemical bonding was confirmed with FTIR spectroscopy. Varying weight percentages of (5, 10, 15 and 20 wt%) glycidyl F-Al2O3 were reinforced with blend of diaminophenoxydimethylsilane and epoxy resin and then cured with diamonodiphenylmethane. The surface morphology of samples was analyzed before and after UV exposure for 168 h using SEM. The 20 wt% F-Al2O3 reinforced epoxy nanocomposite sample possesses higher thermal stability, higher dielectric constant and better UV radiation resistant properties than that of other weight percentages of F-Al2O3 reinforced epoxy nanocomposites. 相似文献
999.
为了实现高灵敏度紫外探测,基于600×500元紫外电荷耦合器件(Charge-Coupled Device, CCD)
图像传感器,创新性地运用软件开窗技术设计了一种基于数字时间延迟积分(Time Delay Integration, TDI)的
紫外成像系统。具体分析了成像系统的噪声来源以及TDI阶数M对成像系统信噪比的影响,并从理论上分析了
采用M阶数字TDI技术对成像系统信噪比的影响。然后详细介绍了在FPGA内部实现数字TDI算法的情况,并给
出了数据采集系统中的上位机交互流程。实验结果表明,基于数字TDI技术的紫外成像系统可以获得较
高的图像对比度和信噪比以及优良的成像质量。 相似文献
1000.
采用基于蒙特卡罗的多次散射模型,研究无 公共散射体传输模型下紫外光(UV)传输特性,对该模型下 UV在大气中传输的平均散射次数随距离的变化情况、路径损耗随传输距离的变化情况 、脉冲响应时间 延迟随传输距离的变化情况以及脉冲响应曲线随能见度的变化情况进行仿真分析。结果显示 ,无公共散射体 传输模型下的UV至少需要两次的大气散射才能够到达接收端,相同传输距离无公共散 射体传输模型的 路径损耗和脉冲响应时间延迟也远高于有公共散射体传输模型的路径损耗和脉冲响应时间 延迟。通过归 一化得到的随能见度变化的脉冲响应曲线发现,无公共散射体传输模型在大气中传输的 脉冲响应时间 延迟不随能见度的变化而变化,但脉冲响应峰值高度随能见度的增大而增高。 相似文献