Synthese,Kristallstruktur und 121Sb-Mößbauer-Spektrum von [SbCl2(18-Krone-6)]+SbCl6−

Synthesis, Crystal Structure, and ¹²Sb-Mössbauer Spectrum of [SbCl₂(18-Crown-6)]⁺SbCl₆^? The title compound, which has been prepared by the reaction of antimony trichloride and antimony pentachloride in the presence of 18-crown-6 in acetonitrile solution, is characterized by its ¹²¹Sb-Mössbauer spectrum and by an X-ray structure determination. Space group P2₁, Z = 2, 2439 observed unique reflections, R = 0.045, wR = 0.043. Lattice dimensions at ?80°C: a = 780.6(7), b = 1297.5(9), c = 1 278.5(10) pm, β = 100.56(7)°. The structure of [SbCl₂(18-crown-6)]⁺SbCl₆^? contains cations in which the antimony atom in the first coordination sphere is surrounded in a ?-trigonal-bipyramidal fashion by two oxygen atoms of the crown ether in axial position as well as in the equatorial position by the two chlorine atoms and the lone electron pair.     

Quasielastic reactions around the coulomb barrier in 16O+118Sn

Measurement of elastic and quasielastic reaction cross sections were done in ¹⁶O + ¹¹⁸Sn system at two different energies above the barrier. Attempts are being made to understand the results in the framework of coupled reaction channel model.     

Permutation Tests for Multivariate Location Problems

The paper presents some permutation test procedures for multivariate location. The tests are based on projected univariate versions of multivariate data. For one-sample cases, the tests are affine invariant and strictly distribution-free for the symmetric null distribution with elliptical direction and their permutation counterparts are conditionally distribution-free when the underlying null distribution of the sample is angularly symmetric. For multi-sample cases, the tests are also affine invariant and permutation counterparts of the tests are conditionally distribution-free for any null distribution with certain continuity. Hence all of the tests in this paper are exactly valid. Furthermore, the equivalence, in the large sample sense, between the tests and their permutation counterparts are established. The power behavior of the tests and of their permutation counterparts under local alternative are investigated. A simulation study shows the tests to perform well compared with some existing tests in the literature, particularly when the underlying null distribution is symmetric whether light-tailed or heavy-tailed. For revealing the influence of data sparseness on the effect of the test, some simulations with different dimensions are also performed.     

Asymptotic power properties of the Cramér-von Mises test under contiguous alternatives

The asymptotic power of the Cramér-von Mises test (CvM test) when parameters are estimated from the data is studied under certain local (contiguous) alternatives. The notion of (asymptotic) direction and distance from the null hypothesis of alternatives is introduced, and it is shown that there exist directions with maximum, minimum, and arbitrary intermediate power. For each direction, there exists a natural asymptotic testing problem with an uniformly most powerful test that is compared with the CvM test. For that, the notion of asymptotic local efficiency (ALE) of the CvM test is introduced. finally, the influence of more information on the (unknown) parameter is studied for three tests of the CvM-type for independence. it is shown that for certain directions, a better knowledge of the parameter may increase the power, and for other ones decrease it. These properties are analogous to that of the X²-test in similar situations.     

Relative wavefunctions, vertex functions and coupling constants for the virtual decay of 4He

The d + d, t + p and h + n relative wavefunctions and their asymptotic normalizations are considered in the framework of the generator coordinate method (GCM) and compared with ATMS (amalgamation of two-body correlation into multiple scattering processes) method which used the realistic Reid soft core interaction. The asymptotic normalization of relative wavefunctions provide various coupling constants, the cluster probability amplitude (the so-called Z ^1/2-factor) and matter RMS radii. These wavefunctions are also used to obtain ⁴He − d − d, ⁴He − t − p and ⁴He − h − n vertex functions in the virtual decay of ⁴He. The extrapolation of vertex functions for negative values of q ² upto the corresponding poles provide the vertex constants which are comparable with other estimates. It is noticed that in GCM the coupling constants C ² for ⁴He − d − d vertex is less than 2 as has been obtained in the forward dispersion relation technique.     

Growth and form of planetary seedlings: results from a microgravity aggregation experiment

The outcome of the first stage of planetary formation, which is characterized by ballistic agglomeration of preplanetary dust grains due to Brownian motion in the free molecular flow regime of the solar nebula, is still somewhat speculative. We performed a microgravity experiment flown onboard the space shuttle in which we simulated, for the first time, the onset of free preplanetary dust accumulation and revealed the structures and growth rates of the first dust agglomerates in the young solar system. We find that a thermally aggregating swarm of dust particles evolves very rapidly and forms unexpected open-structured agglomerates.     

Methoxylbestimmungen

Ohne Zusammenfassung     

Mikrotitration organischer Verbindungen

Ohne Zusammenfassung