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.     

Post-crash fire testing of titanium fuselages

The problem … maintain fuselage integrity and a survivable cabin environment during a post-crash fire. Its high melting point made titanium an attractive candidate for the large-scale test discussed here. Note: This paper is an adaptation of Report No. FAA-RD-71-3, “Titanium Fuselage Environmental Conditions in Post-Crash Fires,” prepared by the author for the Federal Aviation Administration. The report was also the basis for Mr. Sarkos’ presentation at the 75th Annual Meeting of the National Fire Protection Association in San Francisco on May 18, 1971.     

Geochemistry of some rare earth elements in groundwater,Vierlingsbeek, The Netherlands

Groundwater samples were taken from seven bore holes at depths ranging from 2 to 41m nearby drinking water pumping station Vierlingsbeek, The Netherlands and analysed for Y, La, Ce, Pr, Nd, Sm and Eu. Shale-normalized patterns were generally flat and showed that the observed rare earth elements (REE) were probably of natural origin. In the shallow groundwaters the REEs were light REE (LREE) enriched, probably caused by binding of LREEs to colloids. To improve understanding of the behaviour of the REE, two approaches were used: calculations of the speciation and a statistical approach.For the speciation calculations, complexation and precipitation reactions including inorganic and dissolved organic carbon (DOC) compounds, were taken into account. The REE speciation showed REE(3+), REE(SO(4))(+), REE(CO(3))(+) and REE(DOC) being the major species. Dissolution of pure REE precipitates and REE-enriched solid phases did not account for the observed REEs in groundwater. Regulation of REE concentrations by adsorption-desorption processes to Fe(III)(OH)(3) and Al(OH)(3) minerals, which were calculated to be present in nearly all groundwaters, is a probable explanation.The statistical approach (multiple linear regression) showed that pH is by far the most significant groundwater characteristic which contributes to the variation in REE concentrations. Also DOC, SO(4), Fe and Al contributed significantly, although to a much lesser extent, to the variation in REE concentrations. This is in line with the calculated REE-species in solution and REE-adsorption to iron and aluminium (hydr)oxides. Regression equations including only pH, were derived to predict REE concentrations in groundwater. External validation showed that these regression equations were reasonably successful to predict REE concentrations of groundwater of another drinking water pumping station in quite different region of The Netherlands.     

Stability analysis of simply-supported rectangular plates under non-uniform uniaxial compression using rigorous and approximate plane stress solutions

The non-classical problem of buckling of a simply-supported rectangular plate due to various types of non-uniform compressive edge loads is analysed here. For each case, the elasticity solution for the internal in-plane stress field is obtained rigorously using a superposition of Airy's stress functions and also approximately using extended Kantorovich method. Subsequently, the convergent buckling loads are obtained using Galerkin's method. Results are presented to highlight the dependence of the total buckling load and the corresponding buckled shape on the edge load distribution, as well as to illustrate the applicability of the approximate plane stress solutions.     

Method of Determining Strength and Deformation Characteristics of Soils from Results of Deep Impression of Rod Plates

The possibility of determining strength and deformation characteristics of soils under field conditions using rod plates is discussed. The mutual relationship between these characteristics is established from results of deep impression of these rods.     

Chloroaromatic formation in incineration processes

The high-temperature reactions of chlorinated hydrocarbons are reviewed with a primary focus on the gas-phase molecular growth chemistry and elementary reaction mechanisms leading to the formation of chlorinated benzenes and chlorinated polycyclic aromatic hydrocarbons. Recent heterogeneous mechanistic studies of the chlorination and condensation of aliphatic hydrocarbons at lower temperatures are also summarized. Copper(II) valent species play an important role as catalyst and reagent. The main thermal pathways for chlorinated dibenzodioxins and furans have been deduced by these laboratory experiments, which try to model the complex reality of the post-incineration zone of municipal and hazardous waste incinerators.     

Use of toxicity test results and confrontation of some toxicity test methods with fire scenarios

The enormous, world wide research activity in the field of combustion toxicology has given rise to an impressive amount of toxicity data.

The first part of this paper discusses the problems which arise when such results are used to rank materials in an order of the relative toxicity of their combustion products or in attempting to relate them to toxicological hazard evaluation.

In the second part, after introducing the notion of fire scenarios and describing two such possible situations, existing test methods are compared in relation to their relevance to the scenario parameters. It is shown that none of the evaluated methods completely fulfills the considered conditions.

It is concluded by the authors that agreement on thoroughly described scenarios is necessary for further trials towards international harmonisation and development of test methods.     

Circular footings resting on geotextile-reinforced sand bed

The note pertains to an experimental study made on circular footings resting on semi-infinite layer of sand reinforced with geotextiles. Using the concept of homogenization of such soils, both analytical and numerical analyses have also been conducted to predict the load-settlement behavior and compared with experimental observations. The study highlights the effect of the footing size, number of reinforcing layers, reinforcement placement pattern and bond length and the relative density of the soil on the load-settlement characteristics of the footings.     

Reviews

DROUGHT AND FAMINE IN ETHIOPIA Editor: Abdul Mejid Hussein. African Environment Special Report No. 2, The International African Institute, London, 1976,121 pp. £1.50.

HEDGING (A Practical conservation handbook) Alan Brooks, The British Trust for Conservation Volunteers, The Zoological Gardens, Regents Park, London, 1975. 117 pp. £2.10 inc. postage.

THREE JOURNALS Habitat: Published by : The Council for Nature, The Zoological Gardens, Regents Park, NW1 4RY. At £2.50, or £5.00 per annum.

Recreation News: Published by: The Countryside Commission , John Dower House, Crescent Place, Cheltenham, Glos., GL50 3RA.

The International Journal of Environmental Studies: Published by : Gordon Breach Science Publishers Ltd., 42 William IV Street. London, W.C.2. £17.50 for individuals, £35.00 for Libraries. Habitat

A HISTORY OF LANCASHIRE J.J. Bagley, Phillimore & Co. Ltd., London & Chichester 1976. 128 pp. £4.95.