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71.
In γ-picoline a minimum in the proton spin lattice relaxation time is found at 1/T = 0.44 K-1, suggesting a nearly free methyl group ratation. 相似文献
72.
van den Brom CR Rudolf P Palstra TT Hessen B 《Chemical communications (Cambridge, England)》2007,(46):4922-4924
Molecular recognition between two species of Au55 clusters bearing complementary hydrogen-bonding groups provides a facile route to accomplish solution-based assembly of two-component nanoparticle aggregates. 相似文献
73.
van den Brom CR Vogel N Hauser CP Goerres S Wagner M Landfester K Weiss CK 《Langmuir : the ACS journal of surfaces and colloids》2011,27(13):8044-8053
Symmetric transition metal complexes of 2,4-pentanedione (acetyl acetone) are interfacially active: Spinning drop tensiometry reveals lowering of the interfacial tension at the water-organic interface, most pronounced for [Cr(acac)(3)], [Fe(acac)(3)], [Zr(acac)(4)], and [Hf(acac)(4)]. The interfacial activity is explained by the in situ generation of amphiphilic species. Based on tensiometry and (1)H and diffusion-ordered NMR spectroscopy (DOSY NMR), hydrogen bonding of the organically dissolved complexes with water, in some cases in combination with inner-sphere hydrolytic coordination, is identified as the primary origin of this amphiphilicity. The complexes are a rare example of symmetric molecules that turn amphiphilic only upon interfacial interaction with water. 相似文献
74.
Nikky Kortbeek Aleida Braaksma Ferry HF Smeenk Piet JM Bakker Richard J Boucherie 《The Journal of the Operational Research Society》2015,66(7):1061-1076
The design and operations of inpatient care facilities are typically largely historically shaped. A better match with the changing environment is often possible, and even inevitable due to the pressure on hospital budgets. Effectively organizing inpatient care requires simultaneous consideration of several interrelated planning issues. Also, coordination with upstream departments like the operating theatre and the emergency department is much-needed. We present a generic analytical approach to predict bed census on nursing wards by hour, as a function of the Master Surgical Schedule and arrival patterns of emergency patients. Along these predictions, insight is gained on the impact of strategic (ie, case mix, care unit size, care unit partitioning), tactical (ie, allocation of operating room time, misplacement rules), and operational decisions (ie, time of admission/discharge). The method is used in the Academic Medical Center Amsterdam as a decision-support tool in a complete redesign of the inpatient care operations. 相似文献
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77.
A. F. Deutz H. B. Brom H. Deelen L. J. de Jongh W. J. Huiskamp
K. H. J. Buschow
《Solid State Communications》1986,60(12):917-921We present measurements of the magnetization in very high fields, the low temperature specific heat and the AC susceptibility, both in zero and nonzero magnetic field, of the intermetallic cubic Laves phase compound TmNi2. This material appears to be a singlet-singlet system with an inter-ionic exchange which just exceeds the critical value for magnetic ordering. The absence of a clear anomaly in the specific heat near the ferromagnetic transition temperature Tc = 1.1 K is discussed in a molecular field approximation including crystal field effects. The results of the experiments can qualitatively be described in terms of a set of crystal field parameters corresponding to a Hamiltonian for a system with a distortion from cubic symmetry. 相似文献
78.
J. Baak S.I. Mukhin H.B. Brom M.J.V. Menken A.A. Menovsky 《Physica C: Superconductivity and its Applications》1993,210(3-4):391-400
Specific heat data below 1 K of Bi2Sr2CaCu2O8 and YBa2Cu3O7 are analyzed. For YBa2Cu3O7 the nuclear specific heat, CN, amounts to 38T−2 μJ/mol K. CN for Bi2Sr2CaCu2O8 exceeds that of YBa2Cu3O7 by a factor of 15. The nuclear quadrupolar specific heat contribution alone is insufficient to explain the data for YBa2Cu3O7, while lack of NQR data does not allow such a comparison in Bi2Sr2CaCu2O8 to be made. The contribution to CN from nuclear spins coupled via the contact hyperfine interaction with correlated magnetic spins (in the CuO2 plane) is derived as a function of the correlation length. This contribution can be treated independently from the quadrupolar term. We show that the excess specific heat in YBa2Cu3O7 likely originates in a few percentage of an impurity (oxygen deficient) phase with a strong hyperfine field on the Cu nuclei. 相似文献
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80.
Bakharev ON Abu-Shiekah IM Brom HB Nugroho AA McCulloch IP Zaanen J 《Physical review letters》2004,93(3):037002
By Cu NMR we studied the spin and charge structure in Nd(2-x)Ce(x)CuO(4-delta). For x=0.15, starting from a superconducting sample, the low temperature magnetic order in the sample reoxygenated under 1 bar oxygen at 900 degrees C reveals a peculiar modulation of the internal field, indicative of a phase characterized by large charge droplets ("blob" phase). By prolonged reoxygenation at 4 bars the blobs break up and the spin structure changes to that of an ordered antiferromagnet. We conclude that the superconductivity in the n-type systems competes with a genuine type I Mott-insulating state. 相似文献