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Biomedical subjects

A Marconi

Publications and source records attributed to A Marconi.

78 records · Page 5Linked to original sources
PubMedDate not supplied

Queyrat's erythroplasia of the prepuce: a case-report.

A case of Queyrat's erythroplasia of the prepuce is reported. The Authors emphasize the precancerous role of the lesion because of its high frequency of malignant transformation. Local excision appears to be the only adequate form of treatment.

Erythroplasia↗
PubMedDate not supplied

[Asbestos in brake and clutch factories. Results of an environmental survey].

Asbestos is an essential ingredient of friction materials: an environmental survey has been carried out in a brake and clutch factory to evaluate the exposure to airborne asbestos fibres. The measurement of the fibre concentrations has been carried out by means of personal and general air sampling on membrane filters, and subsequent counting by phase-contrast microscopy (400 X). In 17 out of 19 operations entailing exposure for a full shift, mean concentrations obtained by means of personal sampling exceeded 1 f/cc, in 11 they exceeded 2 f/cc; the maximum mean concentration value (7,2 f/cc) has been found at the preforming presses. The mean value for all the working operations was 2,8 f/cc. In addition total dust levels were determined: from a comparison between numerical and gravimetric concentrations, it appears that, for the same total dust level, the initial manufacturing stages have a greater asbestos risk; the relations between the results of the two analytical techniques are discussed. The results are compared with those reported in the literature for similar factories.

Asbestos↗
PubMedDate not supplied

[A comparison between phase-contrast optical microscopy and scanning electron microscopy for the analysis of air-borne asbestos fibers in an office environment].

There is no general agreement on the relationship between results obtained by optical microscopy (PCOM) and electron scanning microscopy (SEM) or electron transmission microscopy (TEM) for airborne asbestos fibres. However, a considerable amount of data has been produced in latter years indicating that a general correlation factor, not differing greatly from unity, can be established between the two analytical techniques if counts are limited to fibres longer than 5 microns. A study was made of the relationship between SEM and PCOM when used simultaneously for determination of background concentrations of asbestos in office buildings. Twenty-four couples of samples were collected in parallel for PCOM and SEM in different locations distributed over the various floors of two buildings containing amosite sprayed on structural parts. Asbestos and total fibre counts by SEM were performed following the Verein Deutscher Ingenieure (VDI) method 3492. For total fibre counts the European PCOM method was mainly used. Discrimination of asbestos from non-asbestos fibres was performed using criteria based on birefringence and morphological characteristics of fibres. Counts included only those fibres longer than 5 microns, diameter less than 3 microns and aspect ratio greater than 3. Both total fibres and asbestos fibres were recorded separately by PCOM and SEM. the arithmetic and geometric means of the ratio between PCOM and SEM were 1.3 and 1.1 respectively for total fibres and 1.2 and 1.1 for asbestos fibres (excluding one outlying value). The regression study showed a significant linear correlation (P = 0.01) with correlation coefficients of 0.84 for asbestos fibres and 0.52 for total fibres.

Air Pollution, Indoor↗