The spread of fire in corridors

Full- and quarter-scale experimental fires in corridor-room assemblies, using various combinations of floor, wall, and ceiling lining materials, yielded some interesting results. Between the small-and large-scale tests, there were marked differences in the relative effects of floor coverings and ceiling linings. Note: This paper is a contribution from the Division of Building Research, National Research Council of Canada and is published with the approval of the Director of the Division.     

Heavy metals in maternal and cord blood

Heavy metal concentrations have been determined in maternal and cord blood samples collected from mothers in the age group 20-25 years with full-term neonates (37-40 weeks). The concentrations of Pb, Cd, Cu and Zn were found to be low in cord blood as compared to mother's blood and the ratio between cord blood and maternal blood for the respective elements was found to be approximately 0.80, 0.86, 0.47 and 0.40. On the other hand, the concentrations of Fe and Mg in the mother's blood were found to be lower than those in the cord blood. Prenatal exposure to lead in Mumbai, though low (5.1 microg/dl), is approximately 2-3 times higher than that observed in Canada or Italy. A strong correlation (r = 0.79) between the maternal and cord blood lead levels has been observed during the present study.     

Organochlorines in egg samples from Norwegian birds of prey: congener-, isomer- and enantiomer specific considerations

The content of chlorinated persistent organic pollutants was determined in a total of 44 egg samples from 8 different raptor species collected throughout Norway in the period 1991-1997. The content of 8 chlorinated bornanes, 9 chlorinated pesticides, and 15 polychlorinated biphenyl congeners (PCB) were determined. The highest average concentrations for PCB were found for eggs from White-tailed Sea Eagle and Peregrine Falcon (average sum PCB concentration: 8.9 and 9.1 microg/g wet weight (w.w.), respectively). Merlin and Sparrowhawk eggs were the highest contaminated with chlorinated pesticides (average sum pesticide concentration: 3.0 and 4.3 microg/g w.w.). For the first time, the content of chlorobornanes was determined in Norwegian birds of prey eggs. However, only minor contamination compared to PCBs and conventional chlorinated pesticides was found. The highest sum concentration was determined for White-tailed Sea Eagle eggs (0.09 microg/g w.w.). No chlorobornane contamination was found in Osprey and Merlin eggs. No spatial and regional specific trends or pattern distribution were found for organochlorine contamination in the egg samples analysed. In order to gain information about enantiomer specific bioaccumulation and biotransformation capacity of the organism, enantioselective analyses was performed for the chiral contaminants trans-chlordane, oxy-chlordane and the chlorobornane B9-1679 (Parlar #50). Indications for species-dependent deviation from the racemic distribution (enantiomeric ratio = 1) were found. Peregrine Falcon and Merlin eggs were characterised with an extremely high enantiomeric excess of the (-)-trans-chlordane (enantiomeric ratio (ER) <0.01). For Golden Eagle, Goshawk and Sparrowhawk eggs, the ERs were between 0.1 and 0.22 demonstrating also here that the (-)-trans-chlordane was the most abundant enantiomer. For the distribution of oxy-chlordane and B9-1679 enantiomers no species-dependent differences were found. For all species the ER values between 0.3 and 0.8 were determined. Thus, also for oxy-chlordane and B9-1679, the (-)-enantiomers are the most dominating stereoisomers in the birds of prey eggs analysed.     

Trace-metal concentrations in normal human liver: methods to cope with marked variability

Concentrations of trace elements in human tissues characteristically vary widely, and the distributions of most concentrations are skewed to the right. Examination of some of the factors which contribute to the marked variability and skewness of the concentrations revealed that: (1) distributions of concentrations are satisfactorily normal (Gaussian) after logarithmic transformation, (2) ash weight is the best frame of reference in which to report results, (3) the distributions of metal concentrations are not further normalized by adjustments which assume that tissue lipid or collagen contains a fixed fraction of the metal found in the parenchyma, and (4) the choice of sample site within the liver is of minimal significance.     

Microanalysis of anionic surfactants in waste water by infrared spectroscopy

Infrared spectroscopy was applied to identify and determine microamounts of anionic surfactants contained in sewage or river waters. The surfactants tested were linear alkylbenzene sulfonate (LAS), branched alkylbenzene sulfonate (ABS), alpha olefine sulfonate (AOS), fatty alcohol sulfate (AS) and fatty alcohol ethoxy sulfate (AES).Anionic surfactants in waters were extracted by chloroform as methylene blue complexes and sulfate type surfactants, i.e. AS and AES were then removed by subsequent hydrolysis. Residual sulfonate type surfactants were first released from methylene blue complexes by ion exchange technique and then changed to sulfonyl chloride derivatives for infrared spectroscopy. Key bands for the identification of sulfonate type surfactants are 640, 618 and 524 cm⁻¹ for LAS, ABS and AOS, respectively. Sulfate type surfactants was calculated from the difference of methylene blue active substance contents before and after hydrolysis.     

Stable lead isotopes and lake sediments--a useful combination for the study of atmospheric lead pollution history

Analysis of stable lead isotopes and lead concentrations in lake-sediment deposits, not least in varved (annually-laminated) sediments, is a useful method to study lead pollution history. This paper presents details from a study of 31 lakes in Sweden. Using a strong acid digestion of sediment samples and ICP-MS analyses, we have found that Swedish lake sediments have a high natural (pre-pollution) 206[Pb]207[Pb] ratio (mean 1.52+/-0.18, range 1.28-2.01, n=31 lakes). In contrast, atmospheric lead pollution derived from metal smelting processes, coal burning and from alkyl-lead added to petrol has a lower ratio (< 1.2). Consequently, when pollution lead deposition began approximately 3500 years ago, the lead isotope ratio of the sediments started to decline, and in modern sediments it is typically < 1.2. Using the isotope and concentration values and a mixing model, the relative contribution of pollution and natural lead in sediment samples can be calculated. The pollution lead records of the Swedish lake sediments show a consistent picture of the atmospheric lead pollution history. Some noticeable features are the Roman peak (approx. 0 AD), the large and permanent Medieval increase (approx. 1000 AD), peaks at approximately 1200 and 1530 AD, the rapid increase after World War II, the peak in the 1970s, and the large modern decline.     

Combined nitrification/denitrification in a membrane reactor

An ever stricter legislation regulating wastewater leads to an increasing demand for biological treatment plants which are able to selectively eliminate nitrogen from wastewaters with a high influent concentration, even when operating in partial influent mode. A membrane-tube-module (MSM) reactor (Membran-Schlauch-Modul-Reaktor) was constructed and realized in the IUV at the University of Bremen. The present approach makes use of all the various layers of the whole biofilm, enabling nitrification and denitrification processes to run simultaneously in one and the same biofilm under optimized conditions. The biological degradation capacity of the system was first successfully tested with synthetic wastewater, and subsequently in a real application with effluents from a recycling of animal carcasses plant and from a coke-oven plant. A mathematical model was devised which describes this biofilm system. The resulting equations were solved by means of the simulation software AQUASIM.     

Prediction of the effectiveness of rolling dynamic compaction using artificial neural networks and cone penetration test data

Rolling Dynamic Compaction(RDC),which is a ground improvement technique involving non-circular modules drawn behind a tractor,has provided the construction industry with an improved ground compaction capability,especially with respect to a greater influence depth and a higher speed of compaction,resulting in increased productivity. However,to date,there is no reliable method to predict the effectiveness of RDC in a range of ground conditions. This paper presents a new and unique predictive tool developed by means of artificial neural networks(ANNs) that permits a priori prediction of density improvement resulting from a range of ground improvement projects that employed 4-sided RDC modules;commercially known as"impact rollers". The strong coefficient of correlation(i.e. R0.86) and the parametric behavior achieved in this study indicate that the model is successful in providing reliable predictions of the effectiveness of RDC in various ground conditions.     

On the potential of combining neutron activation analysis and particle induced X-ray emission (PIXE) for micro- and microdistribution analysis of hard metals in human tissues

Tungsten carbide and cobalt are the main components of hard metal alloy while other metals such as chromium, niobium, tantalum, titanium and vanadium are sometimes added in smaller amounts. Exposure to hard metal dusts can induce a lung fibrosis with cobalt playing a major role. In order to provide information on the role that each metal may have in causing this disease, determination of the total content and the distribution of inhaled metals in lung tissue of hard metal workers is of paramount importance. However, samples such as transbronchial biopsy and bronchoalveolar lavage (BAL), often used in the medical diagnosis of pneumoconiosis, only allow for a small amount of material. This calls for sensitive and accurate analytical procedures for microdetermination and distribution of metals in pulmonary tissue and cellular material, such as macrophages. This work proposes a combination of sophisticated analytical techniques such as neutron activation analysis (NAA), currently applied to the determination of the total concentration of more than 30 elements in biological specimens, and PIXE analysis, particularly microPIXE, which has a great potential for microdistribution analysis in small biological samples. Principles and perspectives for the combined use of these techniques for the analysis of human tissue are outlined and discussed. NAA: determination of hard metals in lung tissue are carried out by neutron irradiation (2 × 10¹⁴ neutrons cm⁻² s⁻¹) in the HFR reactor of Petten. After neutron activation, radiochemical separations of ⁶⁰Co, ¹⁸⁷W, ¹⁸²Ta, ⁵¹Cr followed by computer-based high resolution gamma ray spectrometry allow the measurement of these elements in pulmonary tissues with sensitivities ranging from 10⁻⁴ μg (Cr) to 10⁻⁶ μg (W). PIXE: this technique is multielemental and of relatively high sensitivity (μg/g) even in small total sample masses of from 10 to 100 μg, thus allowing the analysis of parts of needle biopsies. Whereas PIXE has been successfully applied to many medical problems, its usefulness is limited in the total samples analysis for cobalt-related hard metal disease, due to the low levels of cobalt in tissue combined with severe element interferences from the generally more abundant metal, iron. Nevertheless, microPIXE, a special variety of the method scanning over the sample with a focussed ion beam of about 2 × 2 μm², could complement the NAA findings in total samples in the sense of achieving a microdistribution analysis of hard metals (including cobalt) in suitable thin tissue sections.The availability of specialized facilities at the JRC such as the powerful HFR reactor (Petten), the NAA laboratories (Ispra) and the microPIXE facility (Geel) could represent a European ‘reference pole’ for the study of metals in tissues of hard metal diseased subjects.     

The coagulation of a kaolinite suspension with aluminium sulphate

A study has been made of the coagulation of a 50 mg l⁻¹ aqueous suspension of kaolinite for a range of aluminium sulphate and hydrogen ion concentrations. The rate of flocculation was determined from jar tests after stirring for 1 h. The data permitted a stability limit diagram to be drawn from which some indication of the coagulation mechanisms of the system could be ascertained.