排序方式: 共有108条查询结果,搜索用时 15 毫秒
31.
L. D. Gulay M. Daszkiewicz I. P. Ruda O. V. Marchuk 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(3):i19-i21
Crystals of La2Pb(SiS4)2, dilanthanum(III) lead(II) bis[tetrasulfidosilicate(IV)], were obtained from the La–Pb–Si–S system and structurally characterized using X‐ray single‐crystal diffraction. The La and Pb atoms are coordinated in bicapped trigonal prisms of S atoms, with the Si atoms in tetrahedra. An occupational disorder of the La and Pb centres was refined for one position in the structure. The bicapped trigonal prisms and tetrahedra share edges. A gap located 2.629 (1) Å from the sulfide anions was found around the coordination polyhedra, which makes La2Pb(SiS4)2 a prospective material in crystal engineering. The Si and one S atom lie on a threefold axis. 相似文献
32.
Karadas F Ertas G Ozkaraoglu E Suzer S 《Langmuir : the ACS journal of surfaces and colloids》2005,21(1):437-442
Prolonged exposure to X-rays of HAuCl(4) deposited from an aqueous solution onto a SiO(2)/Si substrate or into a poly(methyl methacrylate) (PMMA) matrix induces reduction of the Au(3+) ions to Au(0) and subsequent nucleation to gold nanoclusters as recorded by X-ray photoelectron spectroscopy. The corresponding major oxidation product is determined as chlorine {HAuCl(4)(ads) + X-rays --> Au(ads) + (3/2)Cl(2)(ads) + HCl(ads)}, which is initially adsorbed onto the surface but eventually diffuses out of the system into the vacuum. The reduced gold atoms aggregate (three-dimensionally) into gold nanoclusters as evidenced by the variation in the binding energy during X-ray exposure, which starts as 1.3 eV but approaches a value that is 0.5 eV higher than that of the bulk gold. The disappearance of the oxidation product (Cl2p signal) and the growth of the nanoclusters (related to the measured binding energy difference between the Si2p of the oxide and Au4f of the reduced gold) exhibit first-order kinetics which is approximately 3 times slower than the reduction of Au(3+), indicating that both of the former processes are diffusion controlled. Similarly, gold ions incorporated into PMMA can also be reduced and aggregated to gold nanoclusters using 254 nm deep UV irradiation in air evidenced by UV-vis-NIR absorption spectrocopy. 相似文献
33.
1-[N-(4-bromophenyl)]aminomethylidene-2(1H)naphthalenone (C17H12NOBr) (1) was synthesized and its crystal structure was determined. Compound (1) is monoclinic, space group P21/n with a = 4.808(1) Å, b = 20.617(1) Å, c = 13.750(1) Å, = 93.004(1)°, V = 1361.11(3) Å3, Z = 4, Dc = 1.592 g·cm–3, (Mo K) = 3.014 mm–1, R = 0.051 for 1013 reflections [I > 2(I)]. There is a strong intramolecular hydrogen bond of distance 2.544(2) Å between the hydroxyl oxygen atom and imine nitrogen atom, the hydrogen atom essentially being bonded to the nitrogen atom. The title molecule is not planar. X-ray crystal structure determination reveals the existence of the keto (or predominantly keto) tautomer in (1). Spectra of compound (1) were observed by IR and NMR, and UV–visible spectra of (1) were studied in different solvents and acidic media. 相似文献
34.
Selim Senkan Kevin Krantz Sukru Ozturk Veysel Zengin Isik Onal 《Angewandte Chemie (International ed. in English)》1999,38(18):2794-2799
Eighty isolated channels are present in the array microreactor system that was coupled to a quadrupole mass spectrometer for high-throughput testing of heterogeneous catalyst libraries. The system was used to monitor the activities, selectivities, and reaction kinetics of 66 ternary Pt/Pd/In catalysts for the dehydrogenation of cyclohexane to benzene over 24 h. It was possible to screen the entire 80-channel library in less than 10 minutes (see picture). 相似文献
35.
Katarzyna Sukowska-Ziaja Gokhan Zengin Agnieszka Gunia-Krzyak Justyna Popi Agnieszka Szewczyk Magdalena Jaszek Jerzy Rogalski Boena Muszyska 《Molecules (Basel, Switzerland)》2022,27(1)
Fungal mycelium cultures are an alternative to natural sources in order to obtain valuable research materials. They also enable constant control and adaptation of the process, thereby leading to increased biomass growth and accumulation of bioactive metabolites. The present study aims to assess the biosynthetic potential of mycelial cultures of six Ganoderma species: G. adspersum, G. applanatum, G. carnosum, G. lucidum, G. pfeifferi, and G. resinaceum. The presence of phenolic acids, amino acids, indole compounds, sterols, and kojic acid in biomass extracts was determined by HPLC. The antioxidant and cytotoxic activities of the extracts and their effects on the inhibition of selected enzymes (tyrosinase and acetylcholinesterase) were also evaluated. The total content of phenolic acids in the extracts ranged from 5.8 (G. carnosum) to 114.07 mg/100 g dry weight (d.w.) (G. pfeifferi). The total content of indole compounds in the extracts ranged from 3.03 (G. carnosum) to 11.56 mg/100 g d.w. (G. lucidum) and that of ergosterol ranged from 28.15 (G. applanatum) to 74.78 mg/100 g d.w. (G. adspersum). Kojic acid was found in the extracts of G. applanatum and G. lucidum. The tested extracts showed significant antioxidant activity. The results suggest that the analyzed mycelial cultures are promising candidates for the development of new dietary supplements or pharmaceutical preparations. 相似文献
36.
Jagdish S. Thakur Houbei Dai Gulay K. Serhatkulu Ratna Naik Vaman M. Naik Alex Cao Abhilash Pandya Gregory W. Auner Rajah Rabah Michael D. Klein Carl Freeman 《Journal of Raman spectroscopy : JRS》2007,38(2):127-134
Raman spectroscopy involves the interaction of light with the molecular vibrations and therefore can provide information about molecular structure, tissue composition and changes in its environment. We explored whether Raman spectroscopy can reliably distinguish mammary tumors from normal mammary tissues and other pathological states in mice. We analyzed a large number of Raman spectra from the tumor and normal mammary glands of mice injected with 4T1 tumor cells, which were collected using a high‐resolution (less than 4 cm−1) Raman spectrometer at a fixed (785 nm) laser excitation wavelength and with 60 mW of laser power. The spectra of normal and tumor mammary glands showed consistent differences in the intensity of certain Raman bands and loss of some bands in the tumor spectra. Multivariate statistical methods—principal component analysis (PCA) and discriminant functional analysis (DFA)—were used to separate the data into different groups of mammary tumors, mastitis, lymph nodes contralateral and tumor‐cell‐injected sides, and normal contralateral and tumor‐cell‐injected sides. We demonstrate that this spectroscopic technique has the feasibility of discriminating tumor and mastitis from normal tissues and other pathological states in a short period of time and may detect tumor transformation earlier than the standard histological examination stage. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
37.
Alex Cao Abhilash K. Pandya Gulay K. Serhatkulu Rachel E. Weber Houbei Dai Jagdish S. Thakur Vaman M. Naik Ratna Naik Gregory W. Auner Raja Rabah D. Carl Freeman 《Journal of Raman spectroscopy : JRS》2007,38(9):1199-1205
This paper introduces a new robust method for the removal of background tissue fluorescence from Raman spectra. Raman spectra consist of noise, fluorescence and Raman scattering. In order to extract the Raman scattering, both noise and background fluorescence must be removed, ideally without human intervention and preserving the original data. We describe the rationale behind our robust background subtraction method, determine the parameters of the method and validate it using a Raman phantom against other methods currently used. We also statistically compare the methods using the residual mean square (RMS) with a fluorescence‐to‐signal (F/S) ratio ranging from 0.1 to 1000. The method, ‘adaptive minmax’, chooses the subtraction method based on the F/S ratio. It uses multiple fits of different orders to maximize each polynomial fit. The results show that the adaptive minmax method was significantly better than any single polynomial fit across all F/S ratios. This method can be implemented as part of a modular automated real‐time diagnostic in vivo Raman system. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
38.
Davut Avcı Sümeyye Altürk Fatih Sönmez Ömer Tamer Adil Başoğlu Yusuf Atalay Belma Zengin Kurt Necmi Dege 《应用有机金属化学》2020,34(4):e5412
A series of mixed-ligand M(II) complexes containing 1,10-phenanthroline (phen) and 3-methylpyridine-2-carboxylic acid (3-mpaH) or 6-methylpyridine-2-carboxylic acid (6-mpaH), namely [Co(3-mpa)2(phen)]·3H2O ( 1 ), [Hg(6-mpa)2(phen)]·2H2O ( 2 ), [Mn(6-mpa)2(phen)]·2H2O ( 3 ), [Co(6-mpa)2(phen)]·H2O ( 4 ) and [Ni(6-mpa)2(phen)]·H2O ( 5 ), were synthesized for the first time. Among them, 1 was obtained as single crystals. The structural characterization for 1 was conducted using X-ray diffraction and that for 2 – 5 using mass spectrometry. The IC50 values for α-glucosidase inhibition of 1 – 5 were obtained as 0.161 to >600 μM. The spectral properties were also investigated using Fourier transform infrared and UV–visible spectra. Furthermore, to investigate the geometrical parameters, spectral and electronic properties and second- and third-order nonlinear optical parameters for 1 – 5 , density functional calculations were applied. 相似文献
39.
Melnychuk Khrystyna Marchuk Oleg Daszkiewicz Marek Gulay Lubomir 《Structural chemistry》2020,31(5):1945-1957
Structural Chemistry - The crystal structures of quaternary R3Fe0.5SnS7, R3Co0.5SnS7 and R3Ni0.5SnS7 (R = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy and Ho) compounds of La3Mn0.5SiS7 structure type (space... 相似文献
40.
Andreana Marino Gokhan Zengin Antonia Nostro Giovanna Ginestra Paola Dugo Francesco Cacciola 《Natural product research》2016,30(22):2620-2623
The antimicrobial activity of acetone, methanol and aqueous extracts of Asphodeline anatolica E. Tuzlaci leaves was evaluated against American type culture collection, food and clinical isolates (Listeria monocytogenes and Staphylococcus aureus including methicillin-resistant strains-MRSA). Biofilm formation, toxicity and characterisation of the polyphenolic content were analysed. The acetone extract demonstrated a higher antibacterial activity against S. aureus including MRSA strains, L. monocytogenes and Pseudomonas aeruginosa than against other extracts. No effect was observed in biofilm formation. The extracts resulted non-toxic against Artemia salina Leach. The phytochemical screening of extracts indicated that they mainly contained six polyphenols identified as catechin 3-O-gallate, protocatechuic acid, diosmin, rutin, cirsimaritin and kaempferol glucoside. This study is the first report on antimicrobial activity and phenolic content of A. anatolica and contributes to enrich the literature data on the biological properties of this plant. A. anatolica leaves have a potential as source of natural antimicrobial compounds. 相似文献