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991.
A.-A.H. Mohamed J. F. Kolb K. H. Schoenbach 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(3):517-522
Micro-plasma jets in atmospheric pressure molecular gases
(nitrogen, oxygen, air) were generated by blowing these gases through direct
current microhollow cathode discharges (MHCDs). The tapered discharge
channel, drilled through two 100 to 200 μm thick molybdenum electrodes
separated by a 200 μm thick alumina layer, is 150 to 450 μm in
diameter in the cathode and has an opening of 100 to 300 μm in diameter
in the anode. Sustaining voltages are 400 to 600 V, the maximum current is
25 mA. The gas temperature of the microplasma inside the microhollow
cathode varies between ~2000 K and ~1000 K depending on current,
gas, and flow rate. Outside the discharge channel the temperature in the jet
can be reduced by manipulating the discharge current and the gas flow to
achieve values close to room temperature. This cold microplasma jet can be
used for surface treatment of heat sensitive substances, and for
sterilization of contaminated areas. 相似文献
992.
Elmouloudi Ed-Dari Mohamed Amine Khamsi 《Proceedings of the American Mathematical Society》2006,134(7):2019-2025
We give a partial answer to the problem of computing the numerical index of for .
993.
Clark TE Makha M Raston CL Sobolev AN 《Dalton transactions (Cambridge, England : 2003)》2006,(46):5449-5453
p-Bu(t)-calix[5]arene forms crystalline inclusion complexes with o- and m-carboranes in toluene or dichloromethane-hexane, but not with the p-isomer, the extended structures being based on 1 : 1 host-guest supermolecules, with the p-Bu(t)-substituents creating a snug fit for o- and m-carborane; p-carborane forms a highly hexane soluble complex, induced by grinding, which crystallizes as fibres. Solution phase studies showed the presence of a 1 : 1 host-guest stoichiometry with all three isomeric carboranes as determined from Job plots. The association constants for the o- and m-carborane complexes are 6.4 +/- 0.3 M(-1) and 3.8 +/- 0.1 M(-1) respectively, whereas the p-isomer is only weakly associated. Competition experiments involving all three isomers show rapid exchange on the NMR time scale, and no selectivity in solution is evident. Selective association involving the o- and m-isomers in the solid state is therefore remarkable, and it is a manifestation of crystal packing forces which embodies the differences in dipole moments of the carboranes. 相似文献
994.
Bugarcić ZD Nandibewoor ST Hamza MS Heinemann F van Eldik R 《Dalton transactions (Cambridge, England : 2003)》2006,(24):2984-2990
Substitution reactions of the complexes [Pd(bpma)(H2O)]2+, [Pd(bpma)Cl]+, [Pd(dien)(H2O)]2+ and [Pd(dien)Cl]+, where bpma = bis(2-pyridylmethyl)amine and dien = diethylentriamine or 1,5-diamino-3-azapentane, with some nitrogen-donor ligands such as triazole, pyrazole, pyrimidine, pyrazine and pyridazine, were studied in an aqueous 0.10 M NaClO4 at pH 2.8 using variable-temperature and -pressure stopped-flow spectrophotometry. The second-order rate constants indicate that the Pd(II) complexes of bpma, viz. [Pd(bpma)(H2O)]2+ and [Pd(bpma)Cl]+, are more reactive than the complexes of dien, viz. [Pd(dien)(H2O)]2+ and [Pd(dien)Cl]+. Also, the aqua complexes, [Pd(bpma)(H2O)]2+ and [Pd(dien)(H2O)]2+, are much more reactive than the corresponding chloro complexes. The most reactive nucleophile of the five-membered rings is triazole and for the six-membered rings the most reactive one is pyridazine. Activation parameters were determined for all reactions and the negative entropies and volumes of activation (Delta S++, Delta V++) support an associative ligand substitution mechanism. The crystal structure of [Pd(bpma)(H2O)](ClO4)2.2H2O was determined by X-ray diffraction. Crystals are monoclinic with the space group P2(1)/c. The coordination geometry of [Pd(bpma)(H2O)]2+ is distorted square-planar. The Pd-N (central) bond distance, 1.958(5) A, is shorter than the other two Pd-N distances, 2.007(5) and 2.009(5) A. The Pd-O distance is 2.043(5) A. 相似文献
995.
Surin M Leclère P De Feyter S Abdel-Mottaleb MM De Schryver FC Henze O Feast WJ Lazzaroni R 《The journal of physical chemistry. B》2006,110(15):7898-7908
In this paper we present a joint experimental and theoretical approach for the study of the assembly of end-substituted oligothiophenes at surfaces with different polarities (i.e., mica vs graphite). Scanning probe microscopy studies of (sub)monolayer deposits show various types of structures (one-dimensional fibrils, two-dimensional regular layers, and monolayers), depending on the nature of the end groups and the substrate. Using molecular modeling with an atomistic approach, we focus on the interplay between the molecule-molecule (and segment-segment) interactions and the molecule-substrate interactions and their influence on the observed morphologies and the stacking geometry. Such information is relevant for controlling the structural order in thin layers of thiophene oligomers for use in field-effect transistor applications, for example, by modifying the nature of dielectric material over which those compounds are deposited. 相似文献
996.
A simple proof for a theorem of Luxemburg and Zaanen 总被引:1,自引:0,他引:1
Mohamed Ali Toumi 《Journal of Mathematical Analysis and Applications》2006,322(2):1231-1234
In this paper a simple proof for the following theorem, due to Luxemburg and Zaanen is given: an Archimedean vector lattice A is Dedekind σ-complete if and only if A has the principal projection property and A is uniformly complete. As an application, we give a new and short proof for the following version of Freudenthal's spectral theorem: let A be a uniformly complete vector lattice with the principal projection property and let 0<u∈A. For any element w in A such that 0?w?u there exists a sequence in A which satisfies , where each element sn is of the form , with real numbers α1,…,αk such that 0?αi?1 (i=1,…,k) and mutually disjoint components p1,…,pk of u. 相似文献
997.
Rute A Sá Ferreira Mohamed Karmaoui Sónia S Nobre Luís D Carlos Nicola Pinna 《Chemphyschem》2006,7(10):2215-2222
In this article a detailed study of the optical properties of lanthanide doped lamellar nanohybrids synthesized by the "benzyl alcohol route" is presented. The synthetic approach results in the formation of a highly ordered lamellar nanocomposite consisting of yttrium or gadolinium oxide crystalline layers with a confined thickness of about 0.6 nm, separated from each other by organic layers of intercalated benzoate molecules. When the inorganic layers are doped with optically-active lanthanide ions they show outstanding emission properties in the green (Tb(3+)), red (Eu(3+)) and near infrared (Nd(3+)). The local environment of the emitting ions and the energy transfer processes involving the phenyl ring of the benzoate complexes and the lanthanide ions are presented, as well as radiance and lifetime measurements. The radiance values are comparable and in some cases even larger than those of standard phosphors, proving that these nanohybrids can compete, from an emission efficiency point of view, with commercial phosphors. Furthermore, in these nanohybrids it is possible by simply changing the excitation wavelength, to tune the emission colour chromaticity without loosing the radiance. 相似文献
998.
We demonstrate a method for generating flow within a microfluidic channel using an optically driven pump. The pump consists of two counter rotating birefringent vaterite particles trapped within a microfluidic channel and driven using optical tweezers. The transfer of spin angular momentum from a circularly polarised laser beam rotates the particles at up to 10 Hz. We show that the pump is able to displace fluid in microchannels, with flow rates of up to 200 microm(3) s(-1) (200 fL s(-1)). The direction of fluid pumping can be reversed by altering the sense of the rotation of the vaterite beads. We also incorporate a novel optical sensing method, based upon an additional probe particle, trapped within separate optical tweezers, enabling us to map the magnitude and direction of fluid flow within the channel. The techniques described in the paper have potential to be extended to drive an integrated lab-on-chip device, where pumping, flow measurement and optical sensing could all be achieved by structuring a single laser beam. 相似文献
999.
Isab AA Wazeer MI 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,65(1):191-195
Complexation of Ag(+) with captopril, 1-[(2S)-3-mercapto-2-methylpropionyl]-L-proline, has been studied by (1)H and (13)C-NMR spectroscopy. The equilibrium constants for the trans to cis isomers of captopril bound to Ag(+) were measured by (1)H NMR spectroscopy. It is observed that the trans isomer of the drug binds more strongly to Ag(+) between pH 5 and 8, as shown by the broadening of the trans isomer's resonances in (13)C NMR spectra on complexation. A monodentate complexation of the trans captopril with Ag(+) via the thiol site is proposed based on the solid-state NMR and IR data. A superior antimicrobial activity is exhibited by the Cap-Ag(I) complex compared to captopril ligand itself against Heterotrotropic Plate Counts (HPC), Pseudomonas aeruginosa and Fecal streptococcus bacteria. 相似文献
1000.
Metal complexes derived from 2,6-pyridinedicarboxaldehydebis(p-hydroxyphenylimine); L1, 2,6-pyridinedicarboxaldehydebis (o-hydroxyphenylimine); L2, are reported and characterized based on elemental analyses, IR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The complexes are found to have the formulae [MX2(L1 or L2)] x nH2O, where M=Fe(II), Co(II), Ni(II), Cu(II) and Zn(II), X=Cl in case of Fe(II), Co(II), Ni(II), Cu(II) complexes and Br in case of Zn(II) complexes and n=0-2.5. The molar conductance data reveal that the chelates are non-electrolytes. IR spectra show that the Schiff bases are coordinated to the metal ions in a terdentate manner with NNN donor sites of the pyridine-N and two azomethine-N. From the magnetic and solid reflectance spectra, it is found that the geometrical structure of these complexes are trigonal bipyramidal (in case of Co(II), Ni(II), Cu(II) and Zn(II) complexes) and octahedral (in case of Fe(II) complexes). The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the coordinated water, anions and ligands (L1 and L2) in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the TG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent organic ligands against one or more bacterial species. 相似文献