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排序方式: 共有285条查询结果,搜索用时 15 毫秒
1.
Shoaib Ahmad 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):309-318
The mechanisms and processes of the formation of the regenerative soot in a graphite hollow cathode discharge that produces
and emits carbon clusters are presented. Mass spectrometry with a specially designed E×B velocity filter analyzes the entire range of the charged clusters from C
1 to ∼C
4300. The state of the carbon vapour within the source is evaluated by using the characteristic line emissions from the carbonaceous
discharge whose formative mechanisms depend upon the kinetic and potential sputtering of the sooted cathode. The carbonaceous
discharge generates atomic and ionic C and its clusters C
m (m≥ 2), noble gas metastable atoms and ions, energetic electrons and photons in the cavity of the graphite hollow cathode. The
parameters of soot formation and its recycling depend critically on the discharge parameters, the geometry of the hollow cathode
and 3D profile of the cusp magnetic field contours.
Received 2nd July 2001 and Received in final form 10 September 2001 相似文献
2.
Martin L. Bennink Dessy N. Nikova Kees O. van der Werf Jan Greve 《Analytica chimica acta》2003,479(1):3-15
Atomic force microscopy (AFM) imaging of static DNA-protein complexes, in air and in liquid, can be used to directly obtain quantitative and qualitative information on the structure of different complexes. For example, DNA length, the location of preferential binding sites for proteins and bending of DNA as a result of the complexation can all be measured. Recording consecutive AFM images of DNA and protein molecules under conditions that they are still able to move and interact, or dynamic AFM imaging, however, can reveal information on the dynamic aspects of the interactions between these molecules. Here, an overview is given of the technical challenges that need to be considered for successful dynamic AFM imaging studies of individual DNA-protein interactions. Necessary technical improvements to the AFM set-up and the development of new sample preparation methods are described in this paper. 相似文献
3.
《Electroanalysis》2003,15(22):1787-1794
Surface electrode reactions involving lateral uniform interactions between adsorbed species is studied by means of square‐wave voltammetry (SWV). Interactions are represented by the interaction product aΘ, were a is the Frumkin interaction parameter (a is positive for attraction and negative for repulsion forces) and Θ is the surface coverage. The properties of the SW voltammetric response enable detection of interactions and recognition of the type of interaction forces by a simple procedure. The influence of the interactions on the apparent electrochemical reversibility of the surface electrode reaction is studied in detail. Utilizing “quasireversible maximum” the simple methodology for estimation of the standard redox rate constant without knowing the exact value of the interaction product aΘ is developed. Theoretical predictions are illustrated and confirmed by experiments with Mo(VI) in the presence of phenantroline and an excess of fulvic acids. 相似文献
4.
An additive procedure (SIBFA) is developed for the rapid computation of conformational energy variations in very large molecules. The macromolecule is built out of constitutive molecular fragments and the intramolecular energy is computed as a sum of interaction energies between the fragments. The electrostatic and the polarization components are calculated using multicenter multipole expansions of theab initio SCF electron density of the fragments. The repulsion component is obtained as a sum of bond and lone pair interactions.Tests of the procedure on a series of model compounds containing ether oxygens and pyridine-like nitrogens are reported and compared with the results of correspondingab initio SCF calculations. The resulting methodology is compatible with the simultaneous computation of intermolecular interactions. 相似文献
5.
The reaction of cis-[ClP(μ-NtBu)]2 with N,N′-dimethylurea leads to the formation of both mono- and di-substituted derivatives [ClP(μ-NtBu)2P(NMeCON(H)Me)] and [(μ-NtBu)P(NMeCON(H)Me)]2, instead of monomeric, dimeric or higher oligomeric macrocycles. The structure of [ClP(μ-NtBu)2P(NMeCON(H)Me)] shows rare non-bonded P?Cl and intermolecular hydrogen bonding interactions leading to a 2D-sheet like structure. 相似文献
6.
A.?González-Pérez J.?M.?RusoEmail author G.?Prieto F.?Sarmiento 《Colloid and polymer science》2004,282(4):351-356
The interactions of sodium dodecyl sulphate with ovalbumin in aqueous solution at room temperature are described for a wide concentration range of both substances. A phase diagram covering a wide range of concentrations shows a total of five different morphologies. Dynamic light scattering of the samples from each morphology offered better understanding of the different structures (between three and four) present in the solution. The amount of ovalbumin present in the solution was confirmed with differential scanning spectroscopy, while the interactions between sodium dodecyl sulphate and ovalbumin were interpreted by zeta potential and electrical conductivity measurements. 相似文献
7.
为探讨咪唑环上取代基团对反应平衡的影响, 在模拟生理条件(0.15 mol·L-1 NaCl溶液)下, 应用多核(1H、13C和51V)、扩散排序谱(DOSY)以及变温NMR等谱学技术研究双过氧钒配合物NH4[OV(O2)2{2-(2’-Pyri-dine)-Imidazole}]·4H2O(简写为bpV(Imi-Py))和咪唑类配体(咪唑、2-甲基鄄咪唑、4-甲基-咪唑和组氨酸)的相互作用, 其从强到弱的顺序为咪唑≈4-甲基-咪唑>2-甲基-咪唑>组氨酸. 研究结果表明, 咪唑环上取代基团空间位阻对反应平衡产生较大影响,同时竞争配位的结果导致新的6 配位过氧物种[OV(O2)2L]-(L 为咪唑类配体)的生成, 当配体为4-甲基-咪唑和组氨酸时, 生成的则是一对异构体. 相似文献
8.
Luca Bernazzani Maria Rita Carosi Celia Duce Paolo Gianni Vincenzo Mollica 《Journal of solution chemistry》2006,35(11):1567-1585
Excess molar volumes, V
m
E, over the whole composition range for binary mixtures of 1-butanol, 2-butanol, and 2-methyl-2-propanol + 1-octanol, or 2-octanol, or di-n-butyl ether, or n-hexylacetate were determined at 298.15 K from density measurements carried out with a vibrating-tube densimeter. Small V
m
E values, both positive and negative, are displayed by mixtures containing 1- or 2-octanol, whereas positive and larger values are always found for mixtures containing dibutyl ether and hexylacetate. These results can be justified in terms of H-bonding interactions and/or steric hindrance due to the branched alkyl chains. Partial molar volumes at infinite dilution of the isomeric butanols in the C8 compounds were also calculated from the apparent molar volumes in dilute solution. The solute-solvent interactions and the effects of the local organisation of the solvent around the butanol molecules were discussed using the void and cavity volumes as different estimates of the intrinsic volume of the molecules. The volumetric behavior of butanols seems to be determined by the solute-solvent interactions rather than packaging effects. 相似文献
9.
D. Mihrin Dr. P. W. Jakobsen A. Voute Dr. L. Manceron Prof. R. Wugt Larsen 《Chemphyschem》2019,20(23):3238-3244
The high-resolution infrared absorption spectrum of the donor bending fundamental band ν of the homodimer (HCN)2 has been collected by long-path static gas-phase Fourier transform spectroscopy at 207 K employing the highly brilliant 2.75 GeV electron storage ring source at Synchrotron SOLEIL. The rovibrational structure of the ν transition has the typical appearance of a perpendicular type band associated with a Σ–Π transition for a linear polyatomic molecule. The total number of 100 assigned transitions are fitted employing a standard semi-rigid linear molecule Hamiltonian, providing the band origin ν0 of 779.05182(50) cm−1 together with spectroscopic parameters for the degenerate excited state. This band origin, blue-shifted by 67.15 cm−1 relative to the HCN monomer, provides the final significant contribution to the change of intra-molecular vibrational zero-point energy upon HCN dimerization. The combination with the vibrational zero-point energy contribution determined recently for the class of large-amplitude inter-molecular fundamental transitions then enables a complete determination of the total change of vibrational zero-point energy of 3.35±0.30 kJ mol−1. The new spectroscopic findings together with previously reported benchmark CCSDT(Q)/CBS electronic energies [Hoobler et al. ChemPhysChem. 19 , 3257–3265 (2018)] provide the best semi-experimental estimate of 16.48±0.30 kJ mol−1 for the dissociation energy D0 of this prototypical homodimer. 相似文献
10.
Jian Zhang Zhao‐Ji Li Yi‐Hang Wen Yao Kang Jian‐Kai Cheng Yuan‐Gen Yao 《无机化学与普通化学杂志》2004,630(15):2731-2735
Two new metal succinates modified by rigid bipyridines, Cd(4, 4′‐bpy)(C4H4O4)·1/4H2O ( 1 ) and Cu(2, 2′‐bpy)(C4H4O4)0.5(NO3)(H2O) ( 2 ) (bpy = bipyridine), have been synthesized by hydrothermal reactions and structurally determined. Complex 1 crystallizes in the orthorhombic space group Cmca with the cell parameters a = 11.696(2), b = 15.554(2), c = 15.874(3) Å, α = β = γ = 90.00°, V = 2888(3) Å3, Z = 8. Complex 2 crystallizes in the triclinic space group with a = 7.077(1), b = 9.838(2), c = 10.461(2) Å, α = 71.941(3)°, β = 73.078(3)°, γ = 74.502(3)°, V = 649.8(2) Å3, Z = 2. In complex 1 , a 2‐D network was formed by Cd‐succinato bonding. The 2‐D networks are pillared by 4, 4′‐bpy ligands, forming a 3‐D grid framework. The 2‐fold interpenetration of the resulting 3‐D frameworks completes the molecular structure. In complex 2 , the CuII atom adopts a distorted octahedral in which the CuII atoms are bridged by two H2O molecules into an infinite zigzag chain, [Cu2(H2O)2(C4H4O4)]n. The neighboring chains are further linked by π‐π stacking interactions into a 2‐D network, and the interlayer hydrogen bonds lead to the final 3‐D crystal structure. 相似文献