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471.
Samir Mohamed Awad Shima Mahmoud Ali Yara Essam Mansour Samar Said Fatahala 《Molecules (Basel, Switzerland)》2021,26(10)
Since herpes simplex virus type 1 (HSV-1) infection is so widespread, several antiviral drugs have been developed to treat it, among which are uracil nucleosides. However, there are major problems with the current medications such as severe side-effects and drug resistance. Here we present some newly synthesized cyclic and acyclic uracil nucleosides that showed very promising activity against HSV-1 compared to acyclovir. 相似文献
472.
Vahid Siahpoush;Vahideh Mohadesi;S. Saeid Taheri; 《等离子体物理论文集》2024,64(2):e202200188
In this article, a plasma-metal model is studied as an electromagnetic absorber for stealth application. Epstain distribution is considered for plasma and the electromagnetic reflection of the structure is analyzed by the Green's function volume integral equation method. The attenuation of microwaves in plasma depends on microwave frequency, plasma electron density, spatial distribution of plasma, collision frequency, and plasma thickness. Using a metaheuristic optimization method, it is possible to change the parameters simultaneously in the specified domains to obtain conditions for which microwaves can be absorbed effectively in the specified frequency. In this paper, optimized plasma parameters related to ideal attenuation in desired frequency band are determined by this method. The advantage of this method is that the intervals related to the plasma parameters are selecting according to the practical conditions and in many cases prevent the production of high volume with high density plasma to achieve effective attenuation. The proposed method can be useful for designing adjustable devices in stealth applications. Proper management of power consumption in these devices is one of the results of adjustment. 相似文献
473.
Zhen Jiang Ming Li Tan Mahdiar Taheri Qiao Yan Takuya Tsuzuki Michael G. Gardiner Broden Diggle Luke A. Connal 《Angewandte Chemie (International ed. in English)》2020,59(18):7049-7056
The most pressing challenges for light‐driven hydrogel actuators include reliance on UV light, slow response, poor mechanical properties, and limited functionalities. Now, a supramolecular design strategy is used to address these issues. Key is the use of a benzylimine‐functionalized anthracene group, which red‐shifts the absorption into the visible region and also stabilizes the supramolecular network through π–π interactions. Acid–ether hydrogen bonds are incorporated for energy dissipation under mechanical deformation and maintaining hydrophilicity of the network. This double‐crosslinked supramolecular hydrogel developed via a simple synthesis exhibits a unique combination of high strength, rapid self‐healing, and fast visible‐light‐driven shape morphing both in the wet and dry state. As all of the interactions are dynamic, the design enables the structures to be recycled and reprogrammed into different 3D objects. 相似文献
474.
We report a simple and facile self-assembly method for the successful fabrication of a biological macromolecule, MnTPPCl (manganese(III) chloride 5,10,15,20-tetraphenylporphyrin), intercalated into gold nanoparticles using the cooperative effects of Sesbania sesban plant. This biohybrid was characterized using various techniques for further investigation. The catalytic activity of this biological hybrid was considered in the production of aldehydes and ketones from primary and secondary alcohols, respectively. Excellent conversions and selectivties were obtained applying Au@MnTPPCl colloidal nanocomposite and NaIO4 as an oxygen donor in ethanol. 相似文献
475.
476.
Tamás Kósa Pedro Coutino Antonio Munoz Bahman Taheri István Jánossy 《Liquid crystals》2019,46(1):145-150
In-plane periodic modulation of the director field of an initially homeotropic liquid crystal layer with negative dielectric anisotropy is studied in external electric field with time varying amplitude envelope. Periodically turning a low frequency electric field on and off the cell, an in-plane periodic modulation of the director develops with a length scale that is orders of magnitude larger than the cell gap and can be as large as couple of centimetres. Doping the liquid crystal layer with low concentration of dichroic dye allows easy mapping of the director. We show that the periodic pattern is a periodic arrangement of +1 and ?1 point defects, so called ‘umbilics’. We argue that the in-plane direction of the director is governed by the local flow that accompanies the turn on and off of the electric field. The finite size and the shape of the cell, incompressibility constraint and the nature of the surface alignment material, all together with the flow, are ultimately responsible for the development of the observed periodic director modulation. 相似文献
477.
In this research, a manganese dioxide/multiwalled carbon nanotube (MnO2/MWCNT) was firstly synthesized and characterized and then was applied as an effective sorbent for removing Cu2+ ions from aqueous solution. The effects of initial concentration, temperature, contact time, pH solution, and sorbent dosage were investigated and the optimum value of each was determined. The Langmuir isotherm model, Freundlich model, and Temkin model were used to fit our experimental results. Ultimately, using the Van't Hoff approach, the thermodynamic functions of the intended adsorption phenomenon such as ΔH°ad, ΔS°ad, and ΔG°ad were estimated. 相似文献
478.
Tomohiro Watanabe Tristan Wagner Gangfeng Huang Jrg Kahnt Kenichi Ataka Ulrich Ermler Seigo Shima 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3544-3548
[Fe]‐hydrogenase (Hmd) catalyzes the reversible hydrogenation of methenyl‐tetrahydromethanopterin (methenyl‐H4MPT+) with H2. H4MPT is a C1‐carrier of methanogenic archaea. One bacterial genus, Desulfurobacterium, contains putative genes for the Hmd paralog, termed HmdII, and the HcgA–G proteins. The latter are required for the biosynthesis of the prosthetic group of Hmd, the iron–guanylylpyridinol (FeGP) cofactor. This finding is intriguing because Hmd and HmdII strictly use H4MPT derivatives that are absent in most bacteria. We identified the presence of the FeGP cofactor in D. thermolithotrophum. The bacterial HmdII reconstituted with the FeGP cofactor catalyzed the hydrogenation of derivatives of tetrahydrofolate, the bacterial C1‐carrier, albeit with low enzymatic activities. The crystal structures show how Hmd recognizes tetrahydrofolate derivatives. These findings have an impact on future biotechnology by identifying a bacterial Hmd paralog. 相似文献
479.
Dr. Qingde Zhuo Dr. Xiaoxi Zhou Dr. Takanori Shima Prof. Dr. Zhaomin Hou 《Angewandte Chemie (International ed. in English)》2023,62(19):e202218606
Dinitrogen (N2) activation and functionalization is of fundamental interest and practical importance. This review focuses on N2 activation and addition to unsaturated substrates, including carbon monoxide, carbon dioxide, heteroallenes, aldehydes, ketones, acid halides, nitriles, alkynes, and allenes, mediated by transition metal complexes, which afforded a variety of N−C bond formation products. Emphases are placed on the reaction modes and mechanisms. We hope that this work would stimulate further explorations in this challenging field. 相似文献
480.
When a single metal fails to promote an efficient Suzuki‐Miyaura coupling reaction at ambient temperature, the synergistic cooperation of two distinct metals might improve the reaction. To examine the synergistic effect of palladium and nickel for catalyzing Suzuki coupling reaction, g‐C3N4 supported metal nanoparticles of PdO, NiO and Pd‐PdO‐NiO were prepared, characterized and their catalytic activities evaluated over different aryl halides at room temperature and 78 °C. The morphological characterization of Pd‐PdO‐NiO/g‐C3N4 demonstrated that the bimetallic particles were uniformly dispersed over the g‐C3N4 layers with diameters ranging from 3.5‐7.7 nm. XPS analysis showed that nanoparticles of Pd‐PdO‐NiO consisted of Pd(II), Pd(0) and Ni(II) sites. The experiments performed on the catalytic activity of Pd‐PdO‐NiO/g‐C3N4 showed that the prepared catalyst demonstrated an efficient activity without using toxic solvents. 相似文献