367 research outputs found
Hexaazide octahedral molybdenum cluster complexes: synthesis, properties and the evidence of hydrolysis
This article reports the synthesis, crystal structure of new molybdenum hexaazide cluster complex (ⁿBu₄N)₂[{Mo₆I₈}(N₃)₆] (3) and comparison of its photophysical and electrochemical properties to those of earlier reported analogues (ⁿBu₄N)₂[{M₆X₈}(N₃)₆] (X = Cl, Br). Additionally, the dimerisation of 3 as a result of hydrolysis was revealed by mass spectrometry and single crystal X-Ray diffraction. Indeed, the structurally characterised compound (ⁿBu₄N)₄[{Mo₆I₈}(N₃)₅)₂O] represents the first example of oxo-bridged dimer of octahedral molybdenum clusters complexes
Form Factors of Composite Systems by Generalized Wigner-Eckart Theorem for Poincar\'e group
The relativistic approach to electroweak properties of two-particle composite
systems developed previously is generalized here to the case of nonzero spin.
This approach is based on the instant form of relativistic Hamiltonian
dynamics. A special mathematical technique is used for the parametrization of
matrix elements of electroweak current operators in terms of form factors. The
parametrization is a realization of the generalized Wigner--Eckart theorem on
the Poincar\'e group, form factors are corresponding reduced matrix elements
and they have the sense of distributions (generalized functions). The
electroweak current matrix element satisfies the relativistic covariance
conditions and in the case of electromagnetic current it also automatically
satisfies the conservation law.Comment: Submitted to Theor. Math. Phy
A comparative study of optical properties and X-ray induced luminescence of octahedral molybdenum and tungsten cluster complexes
© 2017 The Royal Society of Chemistry. Octahedral metal cluster complexes have high potential for biomedical applications. In order to evaluate the benefits of these moieties for combined CT/X-ray luminescence computed tomography, this paper compares photoluminescence, radiodensity and X-ray induced luminescence properties of eight related octahedral molybdenum and tungsten cluster complexes [{M 6 I 8 }L 6 ] n (where M is Mo or W and L is I - , NO 3 - , OTs - or OH - /H 2 O). This article demonstrates that despite the fact that molybdenum cluster complexes are better photoluminescence emitters, tungsten cluster complexes, in particular (Bu 4 N) 2 [{W 6 I 8 }I 6 ], demonstrate significantly higher X-ray induced luminescence due to a combination of relatively good photoluminescence properties and high X-ray attenuation. Additionally, photo-degradation of [{M 6 I 8 }(NO 3 ) 6 ] 2- was evaluated
THE FIRST EXPERIENCE WITH TISSUCOL AT MOSCOW CITY CANCER HOSPITAL SIXTY-TWO
The paper describes the first experience with the fibrin sealant Tissucol at Moscow City Cancer Hospital Sixty-Two. The authors used this agent in different clinical situations. However, Tissucol showed the highest efficacy in arresting long-term severe lymphorrhea. The described clinical case clearly demonstrates the abilities of this agent and allows it to be recommended for use in other areas of oncology
Chiral anomaly for local boundary conditions
It is known that in the zeta function regularization and in the Fujikawa
method chiral anomaly is defined through a coefficient in the heat kernel
expansion for the Dirac operator. In this paper we apply the heat kernel
methods to calculate boundary contributions to the chiral anomaly for local
(bag) boundary conditions. As a by-product some new results on the heat trace
asymptotics are also obtained.Comment: 20 p., late
Interactions of a boson in the component theory
The amplitudes for boson-boson and fermion-boson interactions are calculated
in the second order of perturbation theory in the Lobachevsky space. An
essential ingredient of the used model is the Weinberg's component
formalism for describing a particle of spin , recently developed
substantially. The boson-boson amplitude is then compared with the two-fermion
amplitude obtained long ago by Skachkov on the ground of the hamiltonian
formulation of quantum field theory on the mass hyperboloid, , proposed by Kadyshevsky. The parametrization of the amplitudes by
means of the momentum transfer in the Lobachevsky space leads to same spin
structures in the expressions of matrices for the fermion and the boson
cases. However, certain differences are found. Possible physical applications
are discussed.Comment: REVTeX 3.0 file. 12pp. Substantially revised version of IFUNAM
preprints FT-93-24, FT-93-3
A cosmological constant from the QCD trace anomaly?
According to recent astrophysical observations the large scale mean pressure
of our present universe is negative suggesting a positive cosmological constant
like term. This article addresses the question of whether non-perturbative
effects of self-interacting quantum fields in curved space-times may yield a
significant contribution. Focusing on the trace anomaly of quantum
chromo-dynamics (QCD), a preliminary estimate of the expected order of
magnitude yields a remarkable coincidence with the empirical data, indicating
the potential relevance of this effect. PACS: 04.62.+v, 12.38.Aw, 12.38.Lg,
98.80.Es.Comment: 4 pages, RevTe
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