排序方式: 共有21条查询结果,搜索用时 69 毫秒
11.
The preparation and characterization of selected ammonium and methylammonium tetraazidoaurates(III) are reported. All ammonium salts were shown to be highly explosive materials. The first crystal structure of such an ammonium salt, that of [Me(4)N][Au(N(3))(4)], features polymeric units of the anion, which are linked by weak Au...Au interactions. 相似文献
12.
In this paper, we show that a graphene quantum disk (GQD) can be generated on monolayer graphene via structural modification using the electron beam. The electronic structure and local optical responses of the GQD, supported on monolayer graphene, were probed with electron energy-loss spectrum imaging on an aberration-corrected scanning transmission electron microscope. We observe that for small GQD, ~1.3 nm in diameter, the electronic structure and optical response are governed by the dominating edge states, and are distinctly different from either monolayer graphene or double-layer graphene. Highly localized plasmon modes are generated at the GQD due to the confinement from the edge of the GQD in all directions. The highly localized optical response from GQDs could find use in designing nanoscale optoelectronic and plasmonic devices based on monolayer graphene. 相似文献
13.
Juan-Carlos Ruiz Pierre-Luc Girard-Lauriault Florina Truica-Marasescu Michael R. Wertheimer 《Radiation Physics and Chemistry》2010,79(3):310-314
Nitrogen (N)- and oxygen (O)-rich organic thin films were deposited by vacuum-ultraviolet (VUV)-assisted photo-chemical polymerisation of flowing ethylene (C2H4)–ammonia (NH3) and C2H4–nitrous oxide (N2O) mixtures of varying ratios, R, respectively. The reaction mechanism of these binary gas mixtures was investigated as a function of the wavelength, λ, of two near-mono-chromatic VUV sources. Surface-near compositions of these “UV-PE:N” and “UV-PE:O” films were determined by X-ray photoelectron (XPS), and by Fourier transform (reflection–absorption) infrared (FTIR) spectroscopies. The two types of films were compared with plasma polymers deposited using low-pressure radio-frequency (r.f.) glow discharges in similar gas flow mixtures, “PPE:N” and “PPE:O”. VUV-photochemistry appears to be superior to plasma-chemistry in its capability to produce nearly “mono-functional” organic thin films, ones that are rich in primary amines, –NH2, and in carboxylic acid groups, –COOH, respectively. 相似文献
14.
Gigout A Ruiz JC Wertheimer MR Jolicoeur M Lerouge S 《Macromolecular bioscience》2011,11(8):1110-1119
Low seeding efficiency and poor cell retention under flow-induced shear stress limit the effectiveness of in vitro endothelialization strategies for small-diameter vascular grafts. Primary-amine-rich plasma-polymerized coatings (PPE:N) deposited using low- and atmospheric-pressure plasma discharges on PET and PTFE are evaluated for their ability to improve endothelial cells' kinetics and strength of attachment. PPE:N coatings increase cell adhesion and adhesion rate, spreading, focal adhesion, and resistance to flow-induced shear compared with bare and gelatin-coated PET and PTFE. In particular, about 90% of the cells remain on coated surfaces after 1 h exposure to shear. These coatings, therefore, appear as a promising versatile approach to improve cell seeding strategies for vascular grafts. 相似文献
15.
Pyrazole and its derivatives are considered a privileged N-heterocycle with immense therapeutic potential. Over the last few decades, the pot, atom, and step economy (PASE) synthesis of pyrazole derivatives by multicomponent reactions (MCRs) has gained increasing popularity in pharmaceutical and medicinal chemistry. The present review summarizes the recent developments of multicomponent reactions for the synthesis of biologically active molecules containing the pyrazole moiety. Particularly, it covers the articles published from 2015 to date related to antibacterial, anticancer, antifungal, antioxidant, α-glucosidase and α-amylase inhibitory, anti-inflammatory, antimycobacterial, antimalarial, and miscellaneous activities of pyrazole derivatives obtained exclusively via an MCR. The reported analytical and activity data, plausible synthetic mechanisms, and molecular docking simulations are organized in concise tables, schemes, and figures to facilitate comparison and underscore the key points of this review. We hope that this review will be helpful in the quest for developing more biologically active molecules and marketed drugs containing the pyrazole moiety. 相似文献
16.
Rodolfo Moreno-Fuquen Kevin Arango-Daravia Diana Becerra Juan-Carlos Castillo Alan R. Kennedy Mario A. Macías 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(3):359-371
An efficient approach for the regioselective synthesis of (5‐amino‐3‐methylsulfanyl‐1H‐1,2,4‐triazol‐1‐yl)(2‐fluorophenyl)methanone, C10H9FN4OS, (3), from the N‐acylation of 3‐amino‐5‐methylsulfanyl‐1H‐1,2,4‐triazole, (1), with 2‐fluorobenzoyl chloride has been developed. Heterocyclic amide (3) was used successfully as a strategic intermediate for the preparation of 2‐fluoro‐N‐(3‐methylsulfanyl‐1H‐1,2,4‐triazol‐5‐yl)benzamide, C10H9FN4OS, (4), through a microwave‐assisted Fries rearrangement under catalyst‐ and solvent‐free conditions. Theoretical studies of the prototropy process of (1) and the Fries rearrangement of (3) to provide (4), involving the formation of an intimate ion pair as the key step, were carried out by density functional theory (DFT) calculations. The crystallographic analysis of the intermolecular interactions and the energy frameworks based on the effects of the different molecular conformations of (3) and (4) are described. 相似文献
17.
Loretta Sandoval Juan-Carlos Herraez Gregg Steadman Kent I. Mahan 《Mikrochimica acta》1992,108(1-2):19-27
Comparisons were made of various methods for the homogenization of sediment slurries for the determination of Pb and Cd by ETA-AAS. Homogenization techniques evaluated included the use of impact bead, propeller and foamless generators, vortexing and ultrasonic homogenization. On the basis of precision and accuracy, speed and ease of operation; the ultrasonic homogenization technique was clearly the method of choice. Precision obtained for this method using both reduced PdCl2 modifier and the L'vov platform approaches what is obtained for aqueous solutions. Accuracy for Pb and Cd was excellent using both slurry and aqueous calibration standards with slurry standards being somewhat superior for Cd. 相似文献
18.
Oliver Susan Lei Lei Fan Ka Wai Wang Cheng Baena Juan-Carlos Pham Phuong Lin Qianlan Kabir Imrana I. Wong Edgar H. H. Yuen Anthony Chun Yin Boyer Cyrille Yeoh Guan Heng 《Cellulose (London, England)》2021,28(13):8821-8840
Cellulose - Cotton, the most popular textile fibre used today, suffers from high combustibility and a propensity for microbial growth. In this study, we used oxygen tolerant, visible... 相似文献
19.
20.
Poole RA Bobba G Cann MJ Frias JC Parker D Peacock RD 《Organic & biomolecular chemistry》2005,3(6):1013-1024
The synthesis and photophysical characterisation are reported of a series of cationic, neutral and anionic europium and terbium complexes based on structurally related, nonadentate ligands based on the cyclen macrocycle. Each complex incorporates a tetraazatriphenylene moiety and overall absolute emission quantum yields are in the range 15-40% in aerated aqueous media. Dynamic quenching of the lanthanide excited state occurs with electron-rich donors, e.g. iodide, ascorbate and urate, and a mechanistic interpretation is put forward involving an electron transfer process. The cationic lanthanide complexes are taken up by NlH/3T3 cells and tend to localise inside the cell nucleus. 相似文献