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91.
Yuan LF Yang J Wang H Zeng C Li Q Wang B Hou JG Zhu Q Chen DM 《Journal of the American Chemical Society》2003,125(1):169-172
Orientationally ordered structures of two-dimensional (2D) C(60) at low temperature have been investigated theoretically and experimentally. Using total energy optimization with a phenomenological potential, we find the ground state is a close packed hexagonal lattice in which all the molecules have the same orientation. Several local minima of the potential energy surface are found to be associated with other 1 x 1 lattices as well as 2 x 2 lattices. The energies of the orientational domain boundaries of the 1x1 lattices are also computed, and two kinds of which yield negative values. A majority of these theoretical findings are confirmed by our low-temperature scanning tunneling microscopy study of a 2D C(60) array supported on a self-assembled monolayer. 相似文献
92.
用自制的N-十二酰基-L-脯氨酸和N-十二酰基-L-脯氨酸-3,5-二甲基苯胺两种L-脯氨酸衍生物作手性流动相添加剂,在氨丙基硅烷化硅胶柱上,用正己烷/异丙醇作流动相,对多种手性化合物进行了高效液相色谱拆分。实验结果表明:用N-十二酰基-L-脯氨酸作添加剂拆分的12种手性化合物,有8种手性化合物能得到拆分,具有较好的手性选择性。虽然用N-十二酰基-L-脯氨酸-3,5-二甲基苯胺作添加剂,手性选择性也较好,但由于含有苯环,紫外吸收增强,基线波动严重。 相似文献
93.
94.
The vanadium trapping effect of Mg and La containing additives in cracking catalyst contaminated with 2300 ppm Ni and 4700 ppm V has been analyzed by microactivity test (MAT) and imaging secondary ion mass spectrometry (SIMS). The results of SIMS imaging are consistent with cracking activity data and show that the La/spinel is a superior vanadium trap for the fluid catalytic cracking of hydrocarbons (FCC) operation. La/spinel serves as a dual function additive for both vanadium trap and SOx removal. The optimum amount of La/spinel added to the cracking catalyst is about 15% by weight. This results in an increased catalytic activity, an increase in gasoline yield, and a decrease in coke and gas factors. The MgAl2O4 phase of Mg/Al2O3 additive is found capable of trapping vanadium while its MgO of Mg/Al2O3 phase can migrate to zeolite particles (the active component of the FCC catalyst) that, in turn, causes a decline in the activity of that catalyst. 相似文献
95.
Hou Y Jaffrezic-Renault N Martelet C Tlili C Zhang A Pernollet JC Briand L Gomila G Errachid A Samitier J Salvagnac L Torbiéro B Temple-Boyer P 《Langmuir : the ACS journal of surfaces and colloids》2005,21(9):4058-4065
To make ultrathin films for the fabrication of artificial olfactory systems, odorant biosensors, we have investigated mixed Langmuir and Langmuir-Blodgett films of odorant-binding protein/amphiphile. Under optimized experimental conditions (phosphate buffer solution, pH 7.5, OBP-1F concentration of 4 mg L(-1), target pressure 35 mN m(-1)), the mixed monolayer at the air/water interface is very stable and has been efficiently transferred onto gold supports, which were previously functionalized by self-assembled monolayers (SAMs) with 1-octadecanethiol (ODT). Atomic force microscopy and electrochemical impedance spectroscopy were used to characterize mixed Langmuir-Blodgett (LB) films before and after contact with a specific odorant molecule, isoamyl acetate. AFM phase images show a higher contrast after contact with the odorant molecule due to the new structure of the OBP-1F/ODA LB film. Non-Faradaic electrochemical spectroscopy (EIS) is used to quantify the effect of the odorant based on the electrical properties of the OBP-1F/ODA LB film, as its resistance strongly decreases from 1.18 MOmega (before contact) to 25 kOmega (after contact). 相似文献
96.
The reactions of 1,4-bis(phenylthio)butane (L) with Ag(I) salts in varied conditions (varying the solvents, metal-to-ligand ratios, and counteranions) lead to the formation of four new two-dimensional (2D) coordination polymers with different network structures: [Ag(2)L(3)(ClO(4))(2)](infinity) 1, [Ag(2)L(3)(ClO(4))(2) x CH(3)OH](infinity) 2, [[AgL(2)](ClO(4))](infinity) 3, and [AgLNO(3)](infinity) 4. All the structures were established by single-crystal X-ray diffraction analysis. Crystal data for 1: triclinic, P-1, a = 11.0253(9) A, b = 11.3455(9) A, c = 11.5231(9) A, alpha = 93.931(2) degrees, beta = 92.689(2) degrees, gamma = 112.9810(10) degrees, Z = 2. 2: triclinic, P-1, a = 11.9147(13) A, b = 16.1534(17) A, c = 16.2259(17) A, alpha = 74.977(2) degrees, beta = 69.030(2) degrees, gamma = 69.986(2) degrees, Z = 2. 3: triclinic, P-1, a = 12.1617(9) A, b = 12.5054(10) A, c = 13.1547(10) A, alpha = 64.3370(10) degrees, beta =85.938 (2) degrees, gamma = 69.3010(10) degrees, Z = 2. 4: monoclinic, P2(1)/c, a = 5.4032(17) A, b = 16.974(6) A, c = 19.489(6) A, beta = 94.234(6) degrees, Z = 4. In all four complexes, each Ag(I) center has a tetracoordination geometry, and the 2D networks consist of fused large macrometallacyclic ring systems. The "hexagonal" 42-membered rings, Ag(6)L(6), observed in 1 and 2 are nearly identical, which could be considered as unique examples of self-sustaining noninterpenetrated frameworks formed with flexible ligands. The repeating rectangular 28-membered macrometallacycle, Ag(4)L(4), is the basis for the network of 3, in which the perchlorate anions occupy the voids to prevent the ring from collapsing. In 4, columns of the fused rectangular 22-membered rings, Ag(4)L(2)(NO(3))(2), are cross-linked through the L ligands to form a unique 2D network consisting of two types of 22-membered repeating units. 相似文献
97.
The photoluminescence of Co-Al-layered double hydroxide 总被引:1,自引:0,他引:1
Shuai Sun Wan Guo Hou 《中国化学快报》2007,18(11):1371-1373
We report a new optical behaviour of pure Co-Al-layered double hydroxide (LDH).It was found that the Co-Al-LDH sample could emit fluorescence without any fluorescent substances intercalated.Its excitation spectrum shows a maximum peak near the wavelength 370nm,the maximum emission peak appears at 430 nm and the photoluminescence colour of the Co-Al-LDH sample is blue.This new optical property will be expected to extend the potential applications of LDHs in optical materials field. 相似文献
98.
Automated hollow fiber-protected dynamic liquid-phase microextraction of pesticides for gas chromatography-mass spectrometric analysis 总被引:2,自引:0,他引:2
Dynamic liquid-phase microextraction (LPME) controlled by a programmable syringe pump was evaluated for extracting pesticides in water prior to GC-MS analysis. A conventional microsyringe with a 1.3-cm length of hollow fiber attached to its needle was connected to a syringe pump to perform the extraction. The microsyringe was used as both the microextraction device as well as the sample introduction device for GC-MS analysis. The attached hollow fiber served as the "holder" and protector" of 3 microl of organic solvent. The solvent was repeatedly withdrawn into and discharged from the hollow fiber by the syringe pump. Pesticides were extracted from 4-ml water samples into the organic solvent impregnated in the hollow fiber. The effects of organic solvents, plunger movement pattern, agitation and extraction time were investigated. Good repeatabilities of extraction performance were obtained, with the RSD values ranging from 3.0% (alachlor) to 9.8% (4-chlorophenol) for the 14 pesticides; most RSD values were under 5.0%. The method provided a 490-fold preconcentration of the target pesticides. The limits of detection were in the range of 0.01-5.1 microg/l (S/N = 3) in the GC-MS selected ion monitoring mode. In addition, sample clean-up was achieved during LPME because of the selectivity of the hollow fiber, which prevented undesirable large molecules from being extracted. A slurry sample (mixture of 40 mg soil/ml of water) containing seven pesticides was extracted using this method which also gave good linearity and precision (most RSDs <7.0%, n = 3). 相似文献
99.
We have developed efficient synthetic routes to obtain a novel building block spiro[[8H]indeno[2,1-b]thiophene-8,9′-fluorene] (SITF), a monothiophene-containing spirobifluorene analogue, and constructed blue light-emitting materials, including 2′,7′-bis([1,1′-biphenyl]-4-yl)-spiro[indeno[2,1-b]thiophene-8,9′-fluorene] (BBP-SITF) and 2′,7′-bis(9,9′-spirobifluoren-2-yl)spiro[[8H]indeno[2,1-b]-thiophene-8,9′-fluorene] (BSBF-SITF). BSBF-SITF has shown to be a stable blue light-emitting material with high PL quantum efficiency (89%) and unique regioselective feature at the C2 of thiophene, which indicate that BSBF-SITF will be useful for constructing complicated optoelectronic systems. 相似文献
100.
Wang Shutao Wang Enbo Hou Yu Li Yangguang Wang Li Yuan Mei Hu Changwen 《Transition Metal Chemistry》2003,28(6):616-620
A novel organic/inorganic hybrid molybdenum phosphate, [NH3(CH2CH2)2NH3]3[NH3(CH2CH2)2NH2]Na5-[Mo6O12(OH)3(PO4)(HPO4)3]2·4H2O (1), involving molybdenum presented in V oxidation, has been hydrothermally prepared and characterized by elemental analysis, i.r., u.v.–vis., x.p.s., t.g. and single crystal X-ray diffraction. The structure of the title compound (1) may be considered to consist of two [Mo6O12(OH)3(PO4)(HPO4)3] units bonded together with NaO6 octahedra, forming dimers. Further, these dimers connect with each other through four Na+ cations as bridges, giving rise to novel one-dimensional chain-like skeleton. Piperazines exist among inorganic chains acting as charge balancing cations. 相似文献