A simple approach to the nuclear dynamics

We propose an approach to the nuclear dynamics which enables us to understand the relations between the time-dependent Hartree-Fock method and the quantumstatistical approach to the heavy ion reactions. The same formalism allows us to generalize the random phase approximation in order to include the spreading width of collective states.     

Phonon detection by shallow electronic trap states in luminescent ZnO

High-frequency acoustic phonons are detected in a ZnO crystal by phonon- induced luminescence radiation. Our experiments indicate that this radiation is caused by recombination processes of carriers captured at very shallow traps with an ionization energy of about 4 meV. Propagation of the phonons is studied by a time of flight method.     

The effect of vacuum polarisation in the calculation of internal conversion coefficients

The effect of vacuum polarisation on internal conversion coefficients is investigated for the nuclear charge numbersZ=26 andZ=80; it contributes less than one percent to the conversion rate.     

Sample optimization and identification of signal patterns of amino acid side chains in 2D RFDR spectra of the alpha-spectrin SH3 domain

Future structural investigations of proteins by solid-state CPMAS NMR will rely on uniformly labeled protein samples showing spectra with an excellent resolution. NMR samples of the solid alpha-spectrin SH3 domain were generated in four different ways, and their (13)C CPMAS spectra were compared. The spectrum of a [u-(13)C, (15)N]-labeled sample generated by precipitation shows very narrow (13)C signals and resolved scalar carbon-carbon couplings. Linewidths of 16-19 Hz were found for the three alanine C(beta )signals of a selectively labeled [70% 3-(13)C]alanine-enriched SH3 sample. The signal pattern of the isoleucine, of all prolines, valines, alanines, and serines, and of three of the four threonines were identified in 2D (13)C-(13)C RFDR spectra of the [u-(13)C, (15)N]-labeled SH3 sample. A comparison of the (13)C chemical shifts of the found signal patterns with the (13)C assignment obtained in solution shows an intriguing match.     

Counter-current chromatography based analysis of synergy in an anti-tuberculosis ethnobotanical

The crude extract of an Alaskan ethnobotanical plant, Oplopanax horridus, was subjected to counter-current chromatography (CCC), and the selected active regions were evaluated for their synergistic effects with an in vitro model of anti-tubercular efficacy. CCC as a support-free high-resolution separation method was employed to preclude potential irreversible absorption to a solid stationary phase. The microplate Alamar blue assay and the isobole method were used to measure the biological activity and eliminate dose-response dependent errors, respectively. Using the combination of CCC, bioassay and isobole method, significant synergistic effects were observed. Among the entire polarity range, fractions with distribution constant between 0.44 and 0.81 showed the most synergistic enhancement with an increase in potency by 108% for the recombined fractions.     

Aluminum speciation and thermal evolution of aluminas resulting from modified Yoldas sols

Aluminas resulting from sols prepared via a modified Yoldas procedure were studied with differential thermal analysis (DTA), differential thermal gravimetrie (DTG), ²⁷Al nuclear magnetic resonance (²⁷Al MAS NMR) and X-ray diffraction (XRD) concerning their thermal properties, aluminum speciation and phase content.Hydrolysis of aluminum-sec-butoxide in aluminum nitrate solutions allowed to prepare stable sols with varying molar ratios, solids contents and pH values. Resulting sols contained different aluminum species including also Al₁₃ polycations. Sol preparation conditions also determined aluminum speciation in solid products obtained after thermal treatments of gels obtained from these sols. Al₁₃ polycations and AlO₅ species were found to play an important role for thermally induced transformation from amorphous products via eta-Al₂O₃ to alpha-Al₂O₃. Intermediately formed eta-Al₂O₃ promotes the phase transformation to alpha-Al₂O₃.