Characterization of wood dust emission from hand-held woodworking machines.

This article focuses on the prevention of exposure to wood dust when operating electrical hand-held sawing and sanding machines. A laboratory methodology was developed to measure the dust concentration around machines during operating processes. The main objective was to characterize circular saws and sanders, with the aim of classifying the different power tools tested in terms of dust emission (high dust emitter vs. low dust emitter). A test set-up was developed and is described and a measurement methodology was determined for each of the two operations studied. The robustness of the experimental results is discussed and shows good tendencies. The impact of air-flow extraction rate was assessed and the pressure loss of the system for each machine established. For the circular saws, three machines over the nine tested could be classified in the low dust emitter group. Their mean concentration values measured are between 0.64 and 0.98 mg/m3 for the low dust emitter group and from 2.55 and 4.37 mg/m3 for the high dust emitter group. From concentration measurements, a machine classification is possible-one for sanding machines and one for sawing machines-and a ratio from 1-7 is obtained when comparing the results. This classification will be helpful when a choice of high performance power tools, in terms of dust emission, must be made by professionals.

Particulate pollutant source evaluation using an inverse method under steady-state conditions.

This article presents a method that enables the generation rate from one or /more particle sources to be estimated, using far-field concentration measurements. The method is made up of two distinct steps; a calibration phase, followed by an estimation phase. The calibration phase makes it possible to create a transfer relationship between a known source ("reference source") and the measurement of the far-field concentration. The second step consists of estimating unknown source generation rates by inverting the transfer relationship and using measurements of far-field concentrations resulting from these unknown sources. In addition, this article presents a technique to improve the positioning of the sensors in the room in which the sources are situated. A numerical study using computational fluid dynamics was first conducted to theoretically validate the estimation method and assist with choosing the sensor positions in the experimental rig. The study established that, with ideal sensors, the difference between the real and estimated generation rates can be accurate to within 0.1%. The method was then deployed on an experimental case. The results confirmed that it is possible to estimate an isolated source. However, the quality of the estimation deteriorated when the source to be estimated was significantly different from the reference source, from an aerodynamic perspective.

Alterations in pentobarbital pharmacokinetics in response to parenteral and enteral alimentation in the rat.

Recent in vitro observations suggest that the intestine, in addition to the liver, may be an important organ of first-pass drug metabolism. While a variety of changes in intestinal morphology and function in response to continuous parenteral and enteral nutrition have been documented, the effect of different routes of alimentation on intestinal drug metabolism has not been previously investigated. Objectives of this study were to assess the contribution of intestinal pentobarbital metabolism to overall in vivo pentobarbital pharmacokinetics in the rat and to determine if differences in pentobarbital pharmacokinetics were seen between parenterally and enterally nourished animals. After 7 days of continuous infusion of amino acid-glucose mixture via a gastric or jugular vein catheter, pharmacokinetic parameters were determined after 40 mg/kg of pentobarbital was given orally or into the portal or femoral vein. Reduced systemic availability of pentobarbital after oral administration as compared to portal vein injection was seen in both alimentation groups indicating that significant intestinal metabolism of pentobarbital occurred in vivo. Total area under the pentobarbital plasma concentration-time curve was significantly greater in parenterally nourished animals as compared with enterally alimented animals after oral, portal vein and systemic vein drug administration. Differences in pentobarbital, pharmacokinetics between the two alimentation groups appeared to be primarly due to effects on hepatic pentobarbital metabolism. While the mechanism producing these changes has not been defined, differences in gut hormones release and/or pancreatic secretion in response to the two routes of alimentation may be contributory. The widespread use of enteral and parenteral alimentation in clinical medicine suggests that studies to determine if nutrition route of administration similarly influences drug metabolism in humans may be indicated.