Development of β-NMR and β-NQR

The β-NMR (nuclear magnetic resonance) and β-NQR (nuclear quadrupole resonance) technique and its ex-perimental set-up have been developed for the first time in China. The lifetime, magnetic moment and spin polarization of ^12B were determ/ned. The experimental results show the reliability of this newly developed β-NMR and β-NQR set-up.     

The SU(3) β-functionat large β

MCRG results are presented for the SU(3) β-function obtained from optimized blockspin transformations at β = 6.9 and 7.2. At both couplings for the shiftΔβ, corresponding to a change of length scale by a factor 2, Δβ = 0.51 is found. Although the error is large, deviations from asymptotic scaling seem to be larger than expected on the basis of earlier calculations.     

Anti-proton scheme of β-disintegration

The author considers the possibility of generalizing known schemes of-decay by means of the anti-proton reaction.     

Nuclear β-decay. I

In order to clarify the validity of the theory of nuclearβ-transition a new formulation is given. The nuclear properties are contained in form factors, arising from a decomposition of the matrix element of the V-A operator for nuclear states. The connection of these form factors with nuclear physics matrix elements is tabulated. The total transition amplitude can be written as an integral over these form factors folded with off-shell amplitudes for elastic and inelastic electron scattering on nuclei.     

Combinatorial chemistry of β-hairpins

Combinatorial chemistry is expanding rapidly both in terms of chemistry development and application to the synthesis of compound libraries for lead discovery and optimization. Combinatorial technologies continue evolving and developing, in fact they are being used as basic research tools in different fields that include peptide/protein folding. This review examines the use of combinatorial chemistry in the design of peptides and protein domains that adopt beta-sheet conformations. In particular, the use of conformationally restricted peptide libraries has allowed the identification of linear peptides that are folded in a beta-hairpin structure in plain aqueous solutions.     

The four-loop dilaton β-function

We employ the identity derived by Curci and Paffuti relating the metric and dilaton β-functions for the bosonic σ-model to deduce the O(α′³) (four-loop) dilaton β-function from the O(α′³) (three-loop) metric β-function. We also give details of an explicit four-loop calculation in partial confirmation of our result.     

Nuclear β-decay. II

A general expression for the beta-decay transition amplitude is evaluated, using the decomposition of the nuclear current matrix element into beta-decay form factors as obtained in the previous paper. For the electron radial wave functions the finite nuclear size is taken into account. Formulas for the spectrum shape factor and the polarisation are calculated.     

Simple Formula of β+-Decay Half-Lives of Nuclei Far From β-Stable Line

We generalize the formula of β⁺-decay half-lives [Phys. Rev. C 73 (2006) 014305] to include all available data of nuclei far from the β-stable line. Good agreement with experimental data is obtained by taking into account the even-odd (e-o) effect. It is shown that the e-o effect on β⁺-decay half-life is apparent for the allowed β⁺-transition, whereas it is not apparent for the first and second forbidden transitions. This demonstrates that the allowed β⁺-transition is more sensitive to the nuclear even-odd effect than the forbidden β⁺-transition. The underlying physics is discussed. This formula can be used to predict the β⁺-decay half-lives of the nuclei far from β-stability. It is useful to experimental physicists for analyzing the data of β⁺-decay.     

Solvent complexes of jet-cooled β-phenylethylamine

Laser-induced fluorescence spectroscopy was used to investigate -phenylethylamine molecules that were cooled via supersonic gas expansions. The bare molecule spectra reveal 0-0 transitions that can be attributed to four separate conformers. Upon the addition of water or alcohol solvents, a series of new peaks is induced that appear to be built off separate bare molecule transitions. This is a pattern that is markedly different from the one seen for solvent addition to tyramine, which includes an-OH in the para position. As a result, definite hypotheses can be made to explain the influence of the para-OH in affecting solvent induced conformations.     

Effect of Stretching on β-Phase Content of Isotactic Polypropylene Melt Containing β-Nucleating Agent

Pure isotactic polypropylene (iPP) and that containing 0.2 wt% of a β-nucleating agent (β-NA) were extruded through a slit die. Simultaneously, the extruded melt was stretched at the die exit with different stretching rates (SR). The change of β-phase content with different SR was investigated by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The results indicate that, for pure iPP, the content of β-phase first increases with increasing SR till it reaches a maximum and then it gradually decreases. However, for the case of β-nucleated iPP, it decreases monotonously with increasing SR. The spatial confinement is considered as the best explanation for the suppression of β-phase in the nucleated iPP melt upon stretching.     

Das β-Spektrum des Tl204

Theβ-spectrum of Tl²⁰⁴ was measured with Tl²⁰⁴ impregnated NaJ(Tl)crystals. The maximumβ-energy was found to be 761±8 keV. The measured deviations from the statistical shape correspond with the theoretical shape factor for first unique forbidden transitions. Aβ-transition into the 375 keV-level of Pb²⁰⁴ could not be found.     

Ordering of hexagonal layers in phase β- and β′-Mg2Al3

Two phases, β and β′, in Mg₂Al₃ have been compared. Structural rod-like domains composed of sets of hexagonal layers have been described. The main set containing 11 layers does not change during β′–β transformation. The short sequences of layers on the β′ phase transform into clusters in the β-phase. The centres of the domains form a superstructure with a modulation vector equal to 3/22.     

Semi-gross theory of nuclear β-decay

The gross theory of β-decay is refined to take into account shell effects of the parent nuclei, and the resulting theory is named semi-gross theory. In this theory, the one-particle energy distribution in the parent nucleus is taken to have structures, and the one-particle strength function is assumed to depend on the quantum numbers of the initial state of the decaying nucleon. β-decay (partial) half-lives are calculated for 1659 nuclides, and the results are compared with experimental data as well as with those calculated by the gross theory. The β-decay strength functions are shown for two selected nuclides, and briefly discussed. These numerical studies confirm that the semi-gross theory includes some part of the shell effects correctly, although there still remain deviations of the theoretical results from experimental data, which should, at least partly, be due to shell effects of the daughter nuclei. Comparison of the present results with microscopic theories shows that the overall accuracy of the semi-gross theory is comparable with those of the microscopic theories.     

Das β-Spektrum des In114

The shape of the In¹¹⁴ β-spectrum has been measured with a magnetic lens spectrometer. The shape factor was found to be essentially allowed. A least square fit gave the following result for the deviation termb/W:b=(5±2)·10^?2 mc². The stated error is the standard deviation only. This result does not agree with the large deviation reported byLanger et al. Additional information is given for the isomeric transition.