US nuclear power performance

During the past decade there has been a steady diminution in the economic expectations and public support for nuclear power in the USA. An increasing number of nuclear plants have been delayed, deferred, or cancelled, and those being completed face unforeseen rising costs. As a result, both the electric utility industry and the public generally perceive nuclear power, based on light water reactor technology, as intrinsically uneconomic and troublesome as a future option for power generation. The authors believe that this is not because of the inherent nature of nuclear power in general or light water reactors in particular. It arises mainly from the adverse regulatory and institutional framework in which electrical utilities and power plant constructors have to operate in the USA.     

Vaginal microbiology of women with acute recurrent vulvovaginal candidiasis

Alterations in the autochthonous vaginal microflora can predispose women to recurring attacks of Candida vaginitis. Quantitative aerobic and anaerobic cultures were obtained from 24 premenopausal women with acute recurrent vulvovaginal candidiasis and from 21 healthy asymptomatic premenopausal women. Lactobacillus species constituted the predominant flora in both groups, with a mean log10 CFU/ml of 8.7, a total isolation rate of 96%, and a mean of 1.6 Lactobacillus species isolated per patient compared with a mean log10 CFU/ml of 8.9, a total isolation rate of 90%, and a mean of 1.2 Lactobacillus species isolated per patient in the vaginitis and control groups, respectively. The results of this small study failed to provide evidence of an altered or abnormal vaginal bacterial flora in women with non-antibiotic-induced recurrent vulvovaginal candidiasis suffering from acute Candida vaginitis.     

Dodecafoam and substitution tilings

We discuss substitution tilings, certain hierarchical, highly structured tilings in the plane or more general geometric spaces. We use “Dodecafoam” as an artful, appealing example.     

Chemical applications of near-field scanning optical microscopy: Surface and near-surface chemical imaging with conventional near-field optical probes and externally illuminated chemically active ion sensors

Near-field optics using force sensing cantilevered optical fibers and micropipettes is used to investigate the chemical distribution of protein complexing dyes in chromosomes and the sensing and chemical imaging of surfaces and nearsurface regions. These results are put in the context of what presently can be considered as a broad picture of near-field optical chemical applications.     

Joining of ZrO2-4.5 wt% Y2O3 (Y-TZP) ceramics using nanocrystalline tape cast interlayers

Nanocrystalline Y-TZP tape casts were used as interlayers to join conventional Y-TZP ceramic pellets. The joining experiments were performed by hot pressing at 1000°C to 1300°C under constant pressure of 55 MPa. Two types of joints were obtained with and without a nanocrystalline interlayer. At 1100°C, the successful joints were enabled only with the interlayer; four point bending test results revealed an average joint strength of 206 ± 10 MPa. The joint strength increased with the joining temperature. The specimens joined at 1300°C with an interlayer exhibited a joint strength of 613 ± 40 MPa, which is 96% of the strength of the ceramic pellets. The interlayer at the joint exhibited homogeneous and crack free microstructure and preserved its nanocrystalline nature at all temperatures. The advantage of the nanocrystalline interlayer for joining is pronounced at lower joining temperatures and most probably for pellets with large grain size.     

Fabrication and characterization of YBa2Cu3O7−x /Sn composite superconductors

YBa₂Cu₃O_7–x /Sn composites containing 5, 10, 15, and 20 wt% Sn were prepared by conventional powder metallurgy and pressureless sintering at 950 °C. Sn caused degradation of the ceramic superconductor by its chemical reaction with Ba, whose extent increased with Sn content. Composites with between 5 and 10 wt% Sn preserved their superconducting critical temperature,T _c, those with higher Sn content exhibited non-zero residual resistivity at low temperatures. Room-temperature resistivity and its thermal coefficient also increased with Sn content. The brittle behaviour of the composites is attributed to oxidation of Sn during sintering.     

Modified atmosphere packaging of fresh mushrooms

The storage life of harvested fruits and vegetables is influenced by their continued respiration and biochemical activity. Lowering the temperature, and modifying the atmosphere surrounding the product, can extend the shelf-life of the produce. Mushrooms (Agaricus bisporus) were placed into different structural containers covered with PVC films and stored at three temperatures. The effect of key variables, such as temperature, respiration rate, critical and optimal concentrations of O₂ and CO₂, package-weight/area ratio and film permeability, were studied. It was concluded that a highly perishable product, such as mushrooms, must be wrapped and refrigerated in order to prevent transpiration and shrivelling. Modified atmosphere packaging (MAP) may be beneficial but was not found to be essential. If a certain batch of mushrooms respires faster than predicted, or is exposed to large temperature fluctuations, MAP could have a damaging effect.     

Effect of conditioners on the flow properties of powdered sucrose

The effect of two anticaking agents, calcium stearate and aluminium silicate, on the physical characteristics of powdered sugar was studied. The compressibility of the powder was found to be a useful criterion for evaluating the cohesiveness of these powders. It was shown that anticaking agents which reduced cohesivehess also reduced compressibility while increasing the initial bulk density. Moisture, which increased cohesivehess, had the opposite effect on compressibility and bulk density. Cohesion and angle of internal friction were measured using the Jenike Flow Factor Tester. Results indicated that collesion decreased with the addition of anticaking agents while increasing with moisture. The angle of internal friction was found to decrease with the addition of calcium stearate while aluminium silicate slightly increased it. Caking observations showed that these flow conditioners acted like anticaking agents and vice versa.