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991.
Costa M Pergola RD Fumagalli A Laschi F Losi S Macchi P Sironi A Zanello P 《Inorganic chemistry》2007,46(2):552-560
The nitrido-encapsulated heterometallic cluster anions [Co(10)Rh(N)2(CO)21](3-) (1), [Co(10)Rh2(N)2(CO)24](2-) (2), and [Co(11)Rh(N)2(CO)24](2-) (3) have been obtained by tailored redox-condensation reactions. These three anions are rare high-nuclearity mixed-metal clusters containing two interstitial nitrogen atoms. Their structures have been determined by single-crystal X-ray diffraction on their [NR4]+ salts (R = Me for 1 and 3, R = Et for 2), and their electrochemical and ESR properties have been studied in detail. It is noteworthy that 1 has an unprecedented stereochemistry that does not exhibit a close geometrical resemblance with the isoelectronic homometallic anion [Co(11)N2(CO)11(mu2-CO)10](3-), and 2, despite its even number of electrons, is a paramagnetic species. 相似文献
992.
Caira MR de Vries EJ Nassimbeni LR 《Chemical communications (Cambridge, England)》2003,(16):2058-2059
The isolation and structural elucidation by single crystal X-ray diffraction of triclinic and monoclinic modifications of an inclusion complex of beta-cyclodextrin with the same guest, methylparaben, are reported. 相似文献
993.
Manea F Bindoli C Polizzi S Lay L Scrimin P 《Langmuir : the ACS journal of surfaces and colloids》2008,24(8):4120-4124
A protocol is reported for the preparation of water-soluble, thiol-protected Au nanoparticles (Au-MPC) where dioctylamine is used as a stabilizing agent when the gold cluster is formed using the two-phase Brust and Schiffrin procedure. The amount of amine controls the size of the nanoparticles in the 1.9-8.9 nm diameter range. The final stabilization of the gold clusters by addition of functionalized thiols is performed under very mild conditions compatible with most biomolecules. The procedure is suitable for a wide variety of functional groups present in the thiol and allows one to use thiol mixtures with a precise control of their composition in the monolayer. As a proof of principle, examples of nanoparticles protected with thiols comprising functional groups ranging from polyethers, saccharides, polyamines and ammonium ions are reported. 相似文献
994.
A potentiometric method is proposed for the determination or boron in silicon, based on dissolution of silicon by treatment with hydrofluoric acid and ammonium fluoride in the presence of hydrogen peroxide, and conversion of boron to fluoroborate ion. The fluoroborate activity is measured with the Orion fluoroborate-selective electrode. Some important points, such as the effect of various interfering ions and the hydrolysis of fluoroborate ion, are described in detail. The method is applied to the determination of boron in silicon containing at least 10 p.p.m. of boron, with a relative standard deviation of ±4%. 相似文献
995.
We construct examples of symplectic half-flat manifolds on compact quotients of solvable Lie groups. We prove that the Calabi-Yau
structures are not rigid in the class of symplectic half-flat structures. Moreover, we provide an example of a compact 6-dimensional
symplectic half-flat manifold whose real part of the complex volume form is d-exact. Finally we discuss the 4-dimensional case.
This work was supported by the Projects M.I.U.R. “Geometric Properties of Real and Complex Manifolds”, “Riemannian Metrics
and Differentiable Manifolds” and by G.N.S.A.G.A. of I.N.d.A.M. 相似文献
996.
The purpose of this work is to understand the effect of an external environment on the adiabatic dynamics of a quantum critical system. By means of scaling arguments we derive a general expression for the density of excitations produced in the quench as a function of its velocity and of the temperature of the bath. We corroborate the scaling analysis by explicitly solving the case of a one-dimensional quantum Ising model coupled to an Ohmic bath. 相似文献
997.
Paula Cojocaru Antonello Vicenzo Pietro Luigi Cavallotti 《Journal of Solid State Electrochemistry》2005,9(12):850-858
Ultra-dispersed diamond UDD particles were codeposited in gold matrix coatings from a sulphite electrolyte, changing bath
load and key operating parameters. The influence of electrolyte pH, current density and bath load on current efficiency, particle
co-deposition, surface morphology and microhardness of composite coatings was investigated. UDD incorporation is mainly affected
by bath load; however, particle embedding is specifically sensitive to electrolyte pH and deposition current density. The
maximum mass fraction of carbon in the coating, about 0.55%, is obtained by depositing from ultrasonically pre-treated electrolytes
with UDD concentration 20 g l−1, pH 9.5 and 3 mA cm−2 . Au/UDD composites are characterised by an increased microhardness and improved wear resistance. When compared to pure gold
coatings which are notoriously weak, Au/UDD electrodeposits from sulphite electrolytes represent a significant improvement.
Presented at the 4th Baltic Conference on Electrochemistry, Greifswald, 13–16, 2005 相似文献
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