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.     

Tunnel fire and life safety within the world road association (PIARC)

This paper presents the global activities of the World Road Association (PIARC) in the area of fire and life safety in road tunnels. It traces the organizational structure in the form of technical committees, its publications, current activities and concludes with a summary as to the position of the organization with regard to fire and life safety in tunnels.     

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.     

A contribution to the study of some greek marbles

The use of marble in Architecture began on the 7th century B.C. and continued to be used without stop untill today. Greece and especially the East Macedonia region is an extremely privileged area on marble deposits both in quantities and qualities and colours. In the present work the main physical and engineering properties of some varieties of greek marbles are given and a comparison with the international standards is made. The experimental material (marbles) was from East Macedonia, Argolida-Arcadia and Magnessia, three of the biggest marble deposit areas in Greece. From the results obtained, it is concluded that the marbles examined satisfy all the international standard codes and thus they can be used as building stones and decoration materials.     

Stress-Strain State of Weak Saturated Clay Beds of Embankments

Results are presented for laboratory and field tests of weak saturated soils serving as beds for embankments in Ho Chi Min City and various regions of the Mekong River Delta (Vietnam). A method is outlined for quantitative evaluation of the stress-strain state (SSS) of the weak saturated clayey beds (plane problem). A method is described for quantitative evaluation of the deformation and stability of weak beds in the initial, intermediate, and stabilized stages of the formation and transformation of the SSS. __________ Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 2–6, September–October, 2005.     

Object–Oriented Enterprise Modeling and Simulation of AEC Projects

In this paper we describe an object–oriented framework for developing enterprise models of Architecture, Engineering, Construction projects, and a methodology for formalizing these models such that they can be used for discrete event simulation of information processing and coordination in project execution. The simulation results can be used to predict the probable effects of carrying out proposed changes in planning and managing projects.
In our enterprise modeling framework we represent engineering design projects in terms of deliverables (requirements and solutions), plans (activities and process relations), and organization (participants and organizational relations). The resulting project model is the starting point for identifying coordination requirements between project team participants. Our methodology uses matrix techniques derived from qualtiy function deployment (QFD) to identify interactions between project requirements and solutions and calculate measures of product complexity . We then describe information flow between project activities in a similar matrix and calculate measures of process uncertainty . Finally, we identify the responsibilities of project team members and use a matrix to point out organizational interdependencies .
We apply our framework and methodology to model and simulate engineering design for a major extension of an electrical power substation. Our simulation results demonstrate how project performance is contingent on the fit between the project policies and the objectives and preferences of the project team.     

A study of the effect of stiffness distribution on nonlinear seismic response of multi-degree-of-freedom structures

The ductility requirement of elastoplastic multi-d.o.f. shear structures is studied by analysing the response obtained through step-by-step integration of the equations of motion for some recorded accelerograms. In view of the high dependence of the structural strength reserve beyond the elastic range on the distribution of plastic deformations in the structure, this paper aims to establish the influence of the stiffness distribution and of the earthquake features on the local ductility demand. Attention is also paid to the analysis of the influence of variation in excitation intensity and duration on the seismic behaviour of the structural models considered. Numerical results show that overall structural ductility alone is not sufficiently representative to evaluate the ultimate state of multi-d.o.f. structures. Local ductility must also be specified in order to create a reliable aseismic design. In this context, the important role played by the distribution of stiffness over the structure is emphasized.     

Interaction of bacteriophage R17 and reovirus type III with the clay mineral allophane

A study has been made of the adsorption of bacteriophage R17 and reovirus type 3 by the amorphous aluminosilicate clay mineral allophane. In agreement with previous studies of virus adsorption to other minerals such as montmorillonite and aluminium hydroxide, the principal factors influencing adsorption were found to be mixing time, pH and the concentrations and isoelectric points of both the virus and the absorbent. However, allophane was found to be a much better adsorbent for reovirus and R17 over the pH range 5–7, the natural pH range of many fresh waters.By using highly purified radioactive reovirus it was possible to follow both the distribution of radioactive virus in a clay suspension and the specific infectivity of the virus. This study revealed that when adsorbed virus was eluted by neutral phosphate solutions it retained its physical integrity but was of a lower specific infectivity.     

Self-purification of rivers a two-phase model for bacterial biodegradation

A simple two-phase model has been developed, which accounts for up to 95% of the total oxygen consumption during the bacterial phase of river self-purification. The two phases are characterized by a logistic model. The first corresponds roughly to a destruction of of the substrate, and is accompanied by the formation of cellular reserves. The second is the consumption of these stored substances, and begins when the external substrate ceases to be more attractive than the endogenous reserves. The cell yield as well as the stored material proportion appear to be constant, while the kinetic parameter ( ) is strongly S₀ dependent. All this can be studied through oxygen balances.