A new VME-based high voltage power supply for large photomultiplier systems

We describe a new high voltage power supply, developed for the leadglass calorimeter of the WA98 experiment at CERN. The high voltage is produced for each of the 10 080 photomultiplier tubes of the detector individually, by the same number of active bases with on-board Greinacher voltage multipliers. The full VME-based HV controller system, which addresses each base via bus cables once per second, is miniaturized and fits into a single VME crate. The main advantages of this approach are the low heat dissipation, the considerably reduced amount of cabling and cost, as well as the high stability and low noise of the system.     

Photoluminescence polarization in strained GaN/AlGaN core/shell nanowires

The optical polarization properties of GaN/AlGaN core/shell nanowire (NW) heterostructures have been investigated using polarization resolved micro-photoluminescence (μ-PL) and interpreted in terms of a strain-dependent 6 × 6 k·p theoretical model. The NW heterostructures were fabricated in two steps: the Si-doped n-type c-axis GaN NW cores were grown by molecular beam epitaxy (MBE) and then epitaxially overgrown using halide vapor phase epitaxy (HVPE) to form Mg-doped AlGaN shells. The emission of the uncoated strain-free GaN NW core is found to be polarized perpendicular to the c-axis, while the GaN core compressively strained by the AlGaN shell exhibits a polarization parallel to the NW c-axis. The luminescence of the AlGaN shell is weakly polarized perpendicular to the c-axis due to the tensile axial strain in the shell.     

Effect of mimosine on DNA synthesis in mammalian cells

We have designed a general protocol to assess the rate of replicon initiation in mammalian cells in the presence of inhibitors of DNA synthesis. It is based on cross-linking DNA in vivo with trioxsalen, which effectively blocks the movement of the replication forks along DNA, while having little effect on initiation of replication. We applied this protocol to study the effect of the plant amino acid mimosine on the rate of replicon initiation in exponentially growing murine erythroleukemia F4N cells. We found out that during the first 2 h after application of 25-400 microM mimosine, the initiation step was inhibited more efficiently than the overall DNA synthesis. In this respect, the effect of mimosine was similar to that of gamma-ray irradiation and differed from that of hydroxyurea and aphidicolin. The results suggest that in addition to inhibiting the elongation step of DNA synthesis, mimosine inhibits the initiation of DNA replication as well.     

Relaxation during drying of hydrated cellulose fibres

Conclusions 1. The authors have studied the kinetics of the change in length and internal stresses during drying of freshly-formed hydrated cellulose fibre.2. It is shown that drying of hydrated cellulose fibre is characterised by alternation of two opposing processes: in the first drying stage, when mainly free moisture is removed and the moisture content falls to 25–30%, the thread becomes longer; with a further decrease in the moisture content, due to removal of adsorbed water, the thread becomes shorter.This characteristic of the behaviour of freshly-formed hydrated cellulose fibre must be taken into account when working out the plant procedure and lay-out for continuous-forming and fibre-dressing machines.All-Union Scientific-Research Institute for Synthetic Fibres (VNIIV). Translated from Khimicheskie Volokna, No. 5, pp. 32–34, September–October, 1969.     

Temperature regimes control during thermal treatment of bodies with organic thermoreactive coatings

An analytical solution for heating (cooling) of a flat composite plate with radiation-convection heat supply and boundary conditions of the first kind is obtained and analyzed.Scientific Research Institute of Building Materials, Tomsk, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 6, pp. 991–997, 1995.     

Radiant-convective heat exchange in turbulent motion of a gas suspension within a tube

A calculation of the temperature field and radiant and convective components of the thermal flux density is performed for combined action of convection and radiation in a dusty gaseous medium.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 5, pp. 716–721, November, 1988.