Permeation of dimethyl sulfoxide through polyethylene membraness

Permeability and diffusion coefficients for dimethyl sulfoxide (DMSO) in polyethylene have been measured by the “time-lag” technique and found to be affected by the adsorption of DMSO vapor in the low-pressure side of the apparatus. An analytical method is described for correcting the apparent permeability coefficients for such adsorption effects. “True” permeability coefficients for DMSO in polyethylene, expressed in units of cm³(STP) – cm/(sec-cm²-cmHg), vary from 0.92 X 10^-7 at 30°C to 1.7 X 10^-7 at 45°C, and their dependence on relative DMSO pressure appears to be small. The energy of activation for the permeation process is 7.1 kcal/mole. The described correction method is also applicable to the permeation of water vapor through polyethylene and poly-(phenylene oxide). The apparent diffusion coefficients could not be corrected by this method. The solubility of DMSO in polyethylene was measured with a Bakr-McBain balance and found to be very small; solubility coefficients are less than 0.8 cm³(STP) DMSO/(cm³ polymer-cmHg). It is concluded that the transport and solution behavior of DMSO in polyethylene is more similar to that of water vapor than to the corresponding behavior of organic vapors.     

Susceptibility of solid 3He near the ordering temperature

The magnetic susceptibility of solid ³He at melting pressure has been measured down to 1.25 mK. Below about 4 mK, the susceptibility begins to rise significantly above the Curie-Weiss behavior followed at higher temperatures.     

Experimental demonstration of a controlled-NOT wave-packet gate

We report the experimental demonstration of a controlled-NOT (CNOT) quantum logic gate between motional and internal-state qubits of a single ion where, as opposed to previously demonstrated gates, the conditional dynamics depends on the extent of the ion's wave packet. Advantages of this CNOT gate over one demonstrated previously are its immunity from Stark shifts due to off-resonant couplings and the fact that an auxiliary internal level is not required. We characterize the gate logic through measurements of the postgate ion state populations for both logic basis and superposition input states, and we demonstrate the gate coherence via an interferometric measurement.     

Tissue distribution and metabolism of the putative cancer chemopreventive agent 3′,4′,5′‐trimethoxyflavonol (TMFol) in mice

3′,4′,5′‐Trimethoxyflavonol (TMFol) is a synthetic flavonol with preclinical cancer chemopreventive properties. The hypothesis was tested that, in mice, p.o. administration of TMFol results in measureable levels of the parent in target tissues. A single oral dose (240 mg/kg) was administered to mice (n = 4 per time point) with time points ranging from 5 to 1440 min. TMFol and its metabolites were identified and quantitated in all tissues by high‐performance liquid chromatography (HPLC). Plasma levels of TMFol were at the limit of quantification or below, although metabolites were identified. Peak levels of TMFol in the gastrointestinal tract and the prostate averaged 1671 ± 265 µg/g (5.3 µmol/g) and 6.0 ± 1.6 µg/g (18.4 nmol/g), and occurred 20 and 360 min post‐dose, respectively. The area under the tissue concentration–time curve (AUC) for TMFol was greater than those of the metabolites, indicating that TMFol is relatively metabolically stable. Micromolar TMFol levels are easily achieved in the prostate and gastrointestinal tract, suggesting that TMFol might exert chemopreventive efficacy at these tissue sites. Further investigations are warranted to elucidate the potential chemopreventive potency of TMFol. Copyright © 2012 John Wiley & Sons, Ltd.     

Monte-Carlo based background reduction and shielding optimisation for a large hyper-pure germanium detector

The performance of a radiation shielding system for a hyper-pure germanium detector has been characterised for Terrestrial radiation sources, Cosmic muons, X-ray fluorescence and the Compton scattering of source photons. Several methods to reduce the background seen are quantified, including increasing the inner radius of the Pb cave, and increasing the thickness of the shielding. Substantial improvements in the reduction of fluorescence X-rays are found to be achievable by modifying the liner thicknesses used. Increasing the Sn liner from 1.5 to 2.5 mm will increase the shielding of Pb X-rays from 95 to 99.5 %. Reducing the Cu liner from 1.0 to 0.5 mm maintains a 99.5 % level of shielding for Sn/Cd X-rays, however it greatly reduces the amount of Compton scattering of source photons into the detector (a process that is shown to cause an order of magnitude more events in the background than X-ray fluorescence). Cosmic muons were found to increase the amount of background radiation seen, both through direct interaction and the production of secondary radiation. The Cosmic muon contribution, however, was found to produce a much smaller effect than that caused by Terrestrial radiation and Compton scattered photons/fluorescence from the source. The total level of background radiation entering the detector chamber was found to decrease up to the full 200 mm of Pb shielding simulated.     

Die colorimetrische Methode zur Bestimmung des gebundenen Kohlenstoffs in Gusseisen und Stahl

Ohne Zusammenfassung     

Two Algorithms for the Multi-Weber Problem

This paper develops two methods for finding building-blocks for solving Rosing's multi-Weber problem as a set-covering problem in zero–one programming. The building blocks are those subsets of the universe of points to be partitioned that do not contain any non-members within their own convex hulls. For a particular universe of 100 cities, there are almost six billion such subsets, and the paper sets out computational methods that make this enumeration feasible. Some of these methods have wider applications, but the central methods are closely tailored to this problem. Means are also suggested for reducing the number of subsets to be enumerated, without ruling out possibly optimal solutions for the complete problem.