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During irradiation in a nuclear reactor, the UO2 fuel and the Zr cladding come into contact due to fuel thermal expansion and cladding creep. The inner surface of the Zr cladding in contact with the UO2 fuel therefore oxidizes. This paper analyzes the microstructure of zirconia formed at the Zr cladding/UO2 interface in two samples with different burnups. It seems that the zirconia develops 'normally' until it comes into contact with the fuel. The development of internal zirconia is, however, constrained mechanically by the contact of the UO2 fuel. Four different zones can be distinguished in the zirconia layer of each sample. In the medium-burnup sample (37 GWd/tU), the zirconia in the first zone in contact with the cladding exhibits the same kind of microstructure as 'ordinary' zirconium oxide formed on the cladding outer surface, which is characterized by columnar and equiaxed grains. Thereafter, two intermediate zones can be observed: a first composed of very small equiaxed grains and a second with a mixture of intermediate and large grains. In the high-burnup sample (61 GWd/tU), zirconia presents a wavy interface with some circumvolutions. The ZrO2 in contact with the fuel is more developed in this case than in the medium-burnup sample, but it shows the same microstructure. [ABSTRACT FROM AUTHOR]

Studies that estimate indoor aeroallergen exposure typically measure a pre-selected limited range of allergens. In this study, inhalable aeroallergen particles were quantified using the halogen immunoassay ( HIA) to determine the contribution of fungal and non-fungal aeroallergens to total allergen exposure. Bioaerosols from 39 homes of fungal-allergic subjects were sampled using inhalable fraction samplers and immunostained by HIA using resident subject's immunoglobulin E (IgE) to detect allergen-laden particles. Fungal aerosols as well as particles carrying mite, cat, and cockroach allergens were identified and enumerated by HIA. Reservoir dust-mite (Der p 1), cat (Fel d 1), and cockroach (Bla g 1) allergen concentrations were quantified by ELISA. Fungal particles that bound subject's IgE in the HIA were 1.7 (bedroom)- and 1.4 (living room)-fold more concentrated than Der p 1, Fel d 1, and Bla g 1 allergen particles combined. Predominant fungal conidia that bound IgE were derived from common environmental genera including Cladosporium and other fungi that produce amerospores. Airborne mite, cat, and cockroach allergen particle counts were not associated with reservoir concentrations determined by ELISA. This study demonstrates that inhalable fungal aerosols are the predominant aeroallergen sources in Sydney homes and should be considered in future exposure assessments. [ABSTRACT FROM AUTHOR]

Simple, inexpensive methods of sampling from allergen reservoirs are necessary for large-scale studies or low-cost householder-operated allergen measurement.We tested two commercial devices: the Indoor Biotechnologies Mitest Dust Collector and the Dräger Bio-Check Allergen Control; two devices of our own design: the Electrostatic Cloth Sampler (ECS) and the Press Tape Sampler (PTS); and a Vacuum Sampler as used in many allergen studies (our Reference Method). Devices were used to collect dust mite allergen samples from 16 domestic carpets. Results were examined for correlations between the sampling methods.With mite allergen concentration expressed asμg/g, the Mitest, the ECS and the PTS correlated with the Reference Method but not with each other. When mite allergen concentration was expressed asμg/m2 the Mitest and the ECS correlated with the Reference Method but the PTS did not. In the high allergen conditions of this study, the Dräger Bio-Check did not relate to any methods.The Mitest Dust Collector, the ECS and the PTS show performance consistent with the Reference Method. Many techniques can be used to collect dust mite allergen samples. More investigation is needed to prove any method as superior for estimating allergen exposure. [ABSTRACT FROM AUTHOR]

Prototype nasal filters were developed to collect inhaled pollen. This study evaluated the efficacy of the filters for prevention of rhinitis symptoms during acute outdoor pollen exposure.A randomized double-blind design was used. Subjects (n = 46) with a history of autumn exacerbation of rhinitis and positive skin test to ragweed, Bermuda and/or Bahia grass wore either active or placebo nasal filters for 2 h in autumn in a park containing these species. Major and Total Symptoms scores were recorded at 0, 30, 60, 90 and 120 min.Subjects wearing active nasal filters had significantly reduced scores, at all time-points compared with placebo group (allP < 0.05). Of 14 individual symptoms measured, seven were significantly reduced (number of sneezes, runny nose, itchy nose, sniffles, itchy throat; itchy eyes and watery eyes) and another three showed a trend towards lower severity. The nasal filters also enabled the resolution of existing symptoms. Maximal difference in symptoms was seen immediately after subjects had spent 20 min sitting beside a large patch of ragweed.This is the first clinical trial of a nasal filter. The results suggest it has potential for enhancing rhinitis management during acute allergen exposure. [ABSTRACT FROM AUTHOR]

This paper presents experimental results concerning the behaviour of ordinary, high-strength and high-performance concretes under constant mechanical loading and increasing temperatures up to near 300 °C. Heat was applied at a rate of 0.1 °C/min such that successive constant temperature levels were reached and maintained sufficiently to ensure internal temperature stabilisation. The analysis of experimental measures focuses on the so-called transient thermal creep, obtained during the transient thermal loading stages. To study the importance of changes in the internal properties, especially those related to free and bound water, some specimens were submitted to a second heating cycle. Test results confirm the existence of transient thermal strains during first heating, and its occurrence during the second cycle only when the maximum temperature of the first cycle was exceeded even if the specimen had spent a recovery period at ambient temperature. The transient thermal creep values were estimated for different temperature levels, above 105 °C, and they were inversely proportional to the water/cement ratio. [ABSTRACT FROM AUTHOR]

Background: Measurement of exposure to the dust mite allergen Der p 1 is important in asthma research and is potentially useful in managing asthma. As no single measure can capture all characteristics of an exposure, it is important to recognize differences in the available methods of measuring exposure to Der p 1. Methods: Fourteen bedrooms and living rooms were sampled using four methods for 1 week. Airborne allergen was sampled by static Institute of Occupational Medicine samplers. Settling dust was collected on Petri dishes and an adhesive–membrane system (A-book). Vacuumed reservoir dust samples were collected from floors at the end of 1 week. Der p 1 was measured in all samples by enzyme-linked immunosorbent assay, except A-books, in which it was measured by Halogen immunoassay. Results: All four methods intercorrelated moderately (r range = 0.40–0.64, P = 0.04), except between allergen in reservoir dust (as μ g/m2 and μ g/g dust) and settling dust by Petri dishes (P = 0.2). Reservoir allergen, expressed as μ g/m2 , did not correlate with any measure, except reservoir allergen expressed as μ g/g (r = 0.39, P = 0.04). No differences in these associations occurred between bedrooms and living rooms. Conclusions: While the four methods examined correlated moderately, all have practical advantages and difficulties. No method can be considered as ideal for measuring individual exposure. For practicality, use of vacuum cleaner and Petri dish methods are recommended. [ABSTRACT FROM AUTHOR]

Summary Background : The eradication of Helicobacter pylori decreases the antisecretory activity of omeprazole and lansoprazole. Rabeprazole is a potent proton pump inhibitor that may not be affected as greatly by H. pylori status. Aim : To compare the effect of H. pylori eradication on intragastric acidity and plasma gastrin during dosing with lansoprazole, omeprazole, rabeprazole and placebo. Methods : Twenty-four healthy H. pylori -infected volunteers were studied on day 7 of dosing with placebo, lansoprazole 30 mg, omeprazole 20 mg and rabeprazole 20 mg, before and at least 5 weeks after H. pylori eradication. On each occasion, the 24-h intragastric acidity was measured by gastric aspiration. Plasma gastrin concentrations were measured hourly from 08.00 to 13.00 h. Results : Sixteen subjects completed the study. For all three drugs and placebo, H. pylori eradication increased intragastric acidity, particularly nocturnal acidity, and decreased plasma gastrin. There were no differences between the three drugs with respect to 24-h acidity, percentage of time pH > 4 or 5-h plasma gastrin, either before or after H. pylori eradication. Before eradication, the percentage nocturnal time at pH > 3 was significantly greater during rabeprazole than during lanso-prazole dosing. Conclusions : The increase in intragastric acidity seen after H. pylori eradication during dosing with proton pump inhibitors is a drug–class effect, particularly affecting nocturnal acid control. This is related to increased spontaneous intragastric acidity after H. pylori eradication. [ABSTRACT FROM AUTHOR]

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Background:Histamine H2-receptor antagonists are available over the counter for the treatment of heartburn. Aim:To compare the effects of low doses of ranitidine and famotidine on intragastric acidity in a three-way crossover study. Methods:Healthy subjects (12 male, 12 female) were dosed on three occasions with single oral doses of placebo, ranitidine, 75 mg, and famotidine, 10 mg, 1 h after lunch. The pH of gastric aspirates was then measured for 20 h. Subjects ate standard meals and snacks. Analysis of variance was used to determine the statistical significance of differences in acidity (mmol/L) during the day (12.30–22.30 hours) and night (22.30–08.30 hours). Results:Ranitidine and famotidine were superior (P < 0.05) to placebo in decreasing acidity for daytime and night-time intervals. There were no significant differences in mean gastric acidity between ranitidine and famotidine during the daytime (11.37 mmol/L vs. 13.42 mmol/L, respectively) and night-time (23.57 mmol/L vs. 24.74 mmol/L, respectively). Intragastric acidity after ranitidine was significantly lower than that after famotidine in the first 2.5-h period following dosing (4.32 mmol/L vs. 9.28 mmol/L; P < 0.05). Conclusions:Lunchtime doses of ranitidine and famotidine decreased acidity during day- and night-time periods. The effect of ranitidine was significantly greater for the first 2.5 h after dosing. [ABSTRACT FROM AUTHOR]

Ranitidine bismuth citrate was compared with an equipotent dose of ranitidine, to determine whether the former, by an anti-Helicobacter pylori activity, would counteract the rise of gastrin resulting from ranitidine's gastric acid antisecretory activity. Twenty four men with duodenal ulcers were studied before and on the 8th day of dosing with either ranitidine bismuth citrate 800 mg twice daily or ranitidine 300 mg twice daily (double blind, randomised, parallel groups). Fasting and postprandial plasma gastrin and plasma pepsinogen I and II concentrations were measured, and a 13C-urea breath test was performed before and on the 8th day of dosing. The 13C-urea breath tests were positive in 21 patients before dosing and remained positive in nine of nine of the ranitidine dosed patients, whereas only two of 12 patients treated with ranitidine bismuth citrate remained positive. The expected rise in meal stimulated plasma gastrin with ranitidine was seen in the 12 patients who received ranitidine but, despite suppression of H pylori urease activity in 10 of 12 patients taking ranitidine bismuth citrate, there was no attenuation of the meal stimulated gastrin rise. There was no significant difference in the mean derived (4 hour) plasma pepsinogen I and II concentrations after dosing with ranitidine or ranitidine bismuth citrate. [ABSTRACT FROM PUBLISHER]