Ignition and Burning of Fibreboard Exposed to Transient Irradiation

Fire Technology - Natural materials like wood are increasingly used in the construction industry, making the understanding of their ignition and burning behaviour in fires crucial. The state of the...     

Polar organic solvent removal in microcosm constructed wetlands

Three polar organic solvents, acetone, tetrahydrofuran (THF) and 1-butanol, were added at 100 mg/l each to post-primary municipal wastewater in order to simulate a mixed waste stream. This mixture was applied to an experimental microcosm subsurface constructed wetland system consisting of replicates of Juncus effusus, Carex lurida, Iris pseudacorus, Pondeteria cordata and unplanted controls in a series of 14-day batch incubations over a yearlong period simulating a summer and winter season. 90% removal of 1-butanol typically took less than 3 days. 90% removal of acetone required from 5 to 10 days in summer and 10 to 14 days in winter. 90% removal of THF required at least 10 days and was frequently not achieved during the 14-day incubations. Initial experiments confirmed that the majority of solvent removal was via microbial bioremediation. Solvent removal was typically better in planted replicates, especially Juncus, regardless of season. The removal rate of all solvents was slower in winter, but the seasonal effect was most pronounced in the unplanted control replicates and least in the Carex and Juncus replicates. Plant and seasonal effects are believed to be due, in part, to variation in metabolic pathways induced by plant and seasonal variation in available root-zone oxygen. Variation in transpiration also influenced species and seasonal effects on THF removal, but not the other more biodegradable solvents. A model based on a prediction of plant uptake of nonionic dissolved chemicals suggests that as much as 39% of the THF in solution could have been removed through plant transpiration.     

Scheduling of deconstruction projects under resource constraints

In many countries a large part of the building stock will have to be maintained, renovated, rehabilitated or even removed in the next few decades. Although profitability will be one of the major requirements to be met when these works are carried out, there will be more and more emphasis on the environmental requirements to be respected. To make the modernization of the building stock more efficient, dismantling with the aim of producing high quality recycling materials at reasonable costs is a promising approach. This paper presents an integrated approach to deconstruction site management that focuses on both economic and environmental goals. As a first step, material flow management aims at the closed-loop recycling of various construction materials. In a second step, resource constrained project planning models are used to evaluate strategies for optimized deconstruction site management. The approach offers high flexibility and can be adapted readily to different conditions. Results show that time and cost for deconstruction can be reduced by more than 50%, together with recycling quotas of more than 90%. Even when resources are strictly limited or when strong budget and time restrictions have to be respected, tremendous improvements in deconstruction site management can be achieved.     

The Propensity of Wooden Crevices to Smoldering Ignition by Firebrands

Fire Technology - Fires occurring at the wildland-urban interface (WUI) have rapidly increased in frequency and severity over the past few decades. As a result of these extreme fires, multiple...     

Determination of radon exhalation from construction materials using VOC emission test chambers

The inhalation of ²²²Rn (radon) decay products is one of the most important reasons for lung cancer after smoking. Stony building materials are an important source of indoor radon. This article describes the determination of the exhalation rate of stony construction materials by the use of commercially available measuring devices in combination with VOC emission test chambers. Five materials – two types of clay brick, clinker brick, light‐weight concrete brick, and honeycomb brick – generally used for wall constructions were used for the experiments. Their contribution to real room concentrations was estimated by applying room model parameters given in ISO 16000‐9, RP 112, and AgBB. This knowledge can be relevant, if for instance indoor radon concentration is limited by law. The test set‐up used here is well suited for application in test laboratories dealing with VOC emission testing.     

Atmospheric mercury depletion event study in Ny-Alesund (Svalbard) in spring 2005. Deposition and transformation of Hg in surface snow during springtime

A field campaign was conducted in Ny-Alesund (78 degrees 54'N, 11 degrees 53'E), Svalbard (Norway) during April and May 2005. An Atmospheric Mercury (Hg) Depletion Event (AMDE) was observed from the morning of April 24 until the evening of April 27. Transport of already Hg and ozone (O3) depleted air masses could explain this observed depletion. Due to a snowfall event during the AMDE, surface snow Hg concentrations increased two fold. Hg deposition took place over a short period of time corresponding to 3-4 days. More than 80% of the deposited Hg was estimated to be reemitted back to the atmosphere in the days following the event. During the campaign, we observed night and day variations in surface snow Hg concentrations, which may be the result of gaseous elemental mercury (GEM) oxidation to divalent Hg at the snow/air interface by daylight surface snow chemistry. Finally, a decrease in the reactive Hg (HgR) fraction of total Hg (HgT) in the surface snow was observed during spring. We postulate that the transformation of HgR to a more stable form may occur in Arctic snow during spring.     

Processing and morphology of molecularly imprinted nylon thin films

The characterization of thin, selectively imprinted films of nylon‐6 was performed. Amino acids were used as template molecules. Spin‐cast films were prepared with sizes ranging from 2 μm to 300 nm, depending on the nylon and template concentration in the casting solution. The morphological characteristics of the film surface were examined by atomic force microscopy, and the structure within the films was observed by freeze‐fracture scanning electron microscopy. The film activity was clearly coordinated with the appearance of nanometer‐sized pores both on the surface and within the film. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2919–2926, 2006     

Quantitative analysis of small angle neutron scattering data from montmorillonite dispersions

A new model is presented which can describe quantitatively the small angle neutron scattering from montmorillonite-type clay dispersions and polymer-clay nanocomposites. The model is shown to be able to describe well the data from a series of dilute montmorillonite in water dispersions in which the deuterium content of the water phase is varied. The fits combined with information from other techniques suggest strongly that H-D exchange occurs in the montmorillonite-water dispersions. Deviations from Q⁻² behaviour often observed experimentally for clay dispersions are convincingly explained by the presence of a small proportion of tactoids.     

3β-Chlorsteroide – Ernährungsphysiologische und toxikologische Eigenschaften in Mäusen

3β-Chlorosteroids - Nutritional and Toxicological Effects in Mice 3-Chlorosteroids, e.g. 3-chlorocholest-5-ene and 3-chlorostigmast-5-ene, are formed from the corresponding sterols during the industrial hydrolysis of proteins for the production of flavor enhancers. In future, these compounds may also attract attention as environmental contaminants. A simple method for the fractionation and quantitative determination of 3β-chlorosteroids by C₁₈ reversed-phase HPLC has been developed and used for the analysis of these chlorinated steroids in protein hydrolysates. In addition, the biological effects of orally administrated 3β-chloro-steroids were tested in mice that were fed 3β-chlorocholest-5-ene and 3β-chlorostigmast-5-ene in doses of 1 and 10 mg/animal/day. The results of our study showed that body and organ weights as well as feed intake of the various experimental groups were not significantly different from those of the control group. The quantitative determination of 3β-chlorosteroids in organs and tissues revealed that intestinal absorption of 3β-chlorocholest-5-ene was higher than that of 3β-chlorostigmast-5-ene. Highest concentration of 3β-chlorocholest-5-ene was detected in liver and adipose tissue. Absorption and distribution in tissues as well as metabolism of both radioactive 3β-chloro-[4-¹⁴C]cholest-5-ene and 3β-chloro-[4-¹⁴C]stigmast-5-ene have also been studied in mice. At 2 hours after stomach incubation of the two substrates, large proportions of radioactivity had passed through the small intestine and were concentrated in the contents of caecum and colon. Only small proportions of radioactivity were detected outside the alimentary canal, predominantly in the liver. Histopathological examination of sections of organs and tissues such as stomach, duodenum, liver, kidneys, and spleen showed no indications of irreversible cell damages caused by 3β-chlorosteroids.