Evidence for non-yrast states in 254No

Evidence for the decay of non-yrast states in ²⁵⁴No has been observed for the first time in an experiment performed at the University of Jyv?skyl?. The experiment employed the JUROGAM array of germanium detectors coupled to the gas-filled recoil separator RITU and the focal-plane spectrometer GREAT. The ground-state rotational band has been tentatively extended up to a spin of 24ℏ and has a smoothly behaving dynamical moment of inertia. It is speculated that the observation of high-energy γ-rays is due to the decay of a K = 3 band-head state.     

Prediction of sinkage and rolling resistance for off-the-road vehicles considering penetration velocity

The use of plate pressure tests is common for the prediction of sinkage and rolling resistance for off-the-road vehicles. Most of these penetration tests are carried out with small penetration bodies in a quasi-static way. However, when vehicles are rolling on soft soil, the soil is charged dynamically. Consequently, this dynamic effect should be considered by the prediction of sinkage and rolling resistance. At the Institute of Automotive Engineering at Hamburg, tests were carried out with penetration bodies in sizes up to 900 cm², which is comparable to the contact area of wheels. The results confirm the influence of the penetration velocity. With a constant load, the body sinkage is smaller at a higher penetration velocity. Also shear tests with shear rings of different sizes have been carried out and an exponential equation for the shear strength, not depending on the shear ring size, was found. A dynamic pressure-sinkage relationship depending on the penetration velocity or driving speed was derived and transferred to the sinkage and rolling resistance of a rigid wheel.     

In vivo photodynamic characteristics of the near-infrared photosensitizer 5,10,15,20-tetrakis(M-hydroxyphenyl) bacteriochlorin

This paper describes the photodynamic characteristics of the new near-infrared photosensitizer 5,10,15,20-tetrakis(m-hydroxyphenyl)bacteriochlorin (mTHPBC or SQN400) in normal rat and mouse tissues. A rat liver model of photodynamic tissue necrosis was used to determine the in vivo action spectrum and the dose-response relationships of tissue destruction with drug and light doses. The effect of varying the light irradiance and the time interval between drug administration and light irradiation on the biological response was also measured in the rat liver model. Photobleaching of mTHPBC was measured and compared with that of its chlorine analog (mTHPC) in normal mouse skin and an implanted mouse colorectal tumor. The optimum wavelength for biological activation of mTHPBC in rat liver was 739 nm. mTHPBC was found to have a marked drug-dose threshold of around 0.6 mg kg-1 when liver tissue was irradiated 48 h after drug administration. Below this administered drug dose, irradiation, even at very high light doses, did not cause liver necrosis. At administered doses above the photodynamic threshold the effect of mTHPBC-PDT was directly proportional to the product of the drug and light doses. No difference in the extent of liver necrosis produced by mTHPBC was found on varying the light irradiance from 10 to 100 mW cm-2. The extent of liver necrosis was greatest when tissue was irradiated shortly after mTHPBC administration and necrosis was absent when irradiation was performed 72 h or later after drug administration, suggesting that the drug was rapidly cleared from the liver. In vivo photobleaching experiments in mice showed that the rate of bleaching of mTHPBC was approximately 20 times greater than that of mTHPC. It is argued that this greater rate of bleaching accounts for the higher photodynamic threshold and this could be exploited to enhance selective destruction of tissues which accumulate the photosensitizer.     

Dynamic properties of water in silicalite-1 powder

Self-diffusion of D₂O in partially filled silicalite-1 crystals was studied at 25°C by ²H nuclear magnetic resonance (NMR) with bipolar field gradient pulses and longitudinal Eddy-current-delay. For the first time, reliable experimental diffusion data for this system were obtained. Analysis of NMR diffusion decays revealed the presence of a continuous distribution of apparent self-diffusion coefficients (SDCs) of water, ranging from 10⁻⁷ to ∼10⁻¹⁰ m²/s, which include values much higher and lower than that of bulk water (∼10⁻⁹ m²/s) in liquid phase. The observed distribution of SDC changes with variation of the diffusion time in the range of 10–200 ms. A two-site Kärger exchange model was successfully fitted to the data. Finally, the water distribution and exchange in silicalite-1 pores were described by taking into account (a) a gas-like phase in the zeolite pores, a gas-like phase in mesopores and an intercrystalline gas-like phase and (b) intercrystalline liquid droplets with intermediate exchange rate with the other phases. The other phases experience fast exchange on the NMR diffusion time scale. Diffusion coefficients and mean residence times of water in some of these states were estimated.     

Recoil-fission tagging of the transfermium nucleus 252No

An in-beam study of the transfermium nucleus ²⁵²No has been performed using the JUROSPHERE II array of germanium detectors coupled to the gas-filled recoil separator RITU. A new technique of recoil-fission tagging was used to extract tagged γ-ray data. Having significant spontaneous fission and α-decay branches, ²⁵²No is an ideal candidate for a comparative study. In a similar manner to α-decay tagging the fission events can be used to obtain γ-ray data. The recoil-fission tagged γ-ray spectrum showed a similar structure to the α-decay tagged γ-ray spectrum. By comparing the α-tagged and fission-tagged spectra and decay curves, it was shown that the spontaneous fission originates from the same initial state as the α decay. This extension of the tagging method allows in-beam spectroscopic data to be obtained from heavy nuclei with significant spontaneous-fission branches.