Plasma cutting is a metal fabrication process that employs an electrically conductive plasma arc to cut metals. The metal fume emitted from stainless steel plasma cutting may consist of hexavalent chromium (Cr6+), which is a carcinogen, and other toxicants. Overexposure to plasma cutting fume may cause pulmonary toxicity and other health effects. This study was to evaluate the effects of operation parameters (arc current and arc time) on the fume formation rates, Cr6+ and other oxides concentrations, particle size distributions (PSD), and particle morphology. A fume chamber and high-volume pump were used to collect fume produced from cutting ER308L stainless steel plates with arc currents varying between 20 and 50 A. The amount of fume collected on glass fiber filters was gravimetrically determined and normalized to arc time. Cr6+ and other oxides in the fume were analyzed using ion chromatography. PSD of the fume was examined using a scanning mobility particle sizer and an aerodynamic particle sizer for fine and coarse fractions, respectively. The particle morphology was imaged through a transmission electron microscope (TEM). Total fume generation rate increased with arc current and ranged from 16.5 mg min-1 at 20 A to 119.0 mg min-1 at 50 A. Cr6+ emissions (219.8-480.0 µg min-1) from the plasma cutting were higher than welding fume in a previous study. Nitrogen oxides level can be an indicator of oxidation level and Cr6+ formation (R = 0.93). Both PSD measurement and TEM images confirmed a multimodal size distribution. A high concentration of a fine fraction of particles with geometric mean sizes from 96 to 235 nm was observed. Higher arc current yielded more particles, while lower arc current was not able to penetrate the metal plates. Hence, the worker should optimize the arc current to balance cut performance and fume emission. The findings indicated that arc current was the dominant factor in fume emission from plasma cutting. Appropriate ventilation and respiratory protection should be used to reduce workers' exposure.

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This study aims to propose a method to calculate optimum exchanged grinding wheel diameter to minimize grinding cost in grinding surface process for stainless steel. The interactions of the grinding cost and optimum exchanged grinding wheel diameter have been analyzed and presented in mathematical formulae. To obtain the minimal grinding cost, the optimal exchanged grinding wheel diameter has been determined by investigating six two-level grinding process parameters including initial grinding wheel diameter, total dressing depth, radial grinding wheel wear per dress, wheel life, machine tool hour and grinding wheel cost. Based on 26 experiments conducted in computational program, the optimal exchanged grinding wheel diameter is presented as a function of these grinding parameters. This developed model has been verified and proven by experimental results. The proposed method of calculation of the optimum exchanged grinding wheel diameter can be applied in practice to reduce the grinding cost.

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The short form of the Experiences in Close Relationships Scale-Revised Child version (ECR-RC) is a promising self-report measure of anxious and avoidant attachment in Western adolescents, yet little is known about its psychometric properties across cultures. More importantly, little is known about attachment styles across cultures, child gender, and parental gender. The present study aims to address these limitations by studying the psychometric properties and measurement invariance of the ECR-RC in a sample of 1,232 Belgian and Vietnamese adolescents (45.9% boys, M age = 12.3, SD = 1.20, range = 9.0-15.0; 61.36% Vietnamese adolescents). Results indicated that the factor structure of the mother-oriented ECR-RC was replicated across a Belgian and a Vietnamese sample and that the scale was invariant across both cultures and across gender and age. Vietnamese adolescents were more avoidantly and anxiously attached to their mothers compared to their Belgian counterparts. Boys were more avoidantly and anxiously attached compared to girls for the total sample. Considering two countries separately, boys were found to be more avoidantly attached, not anxiously attached compared to girls. Furthermore, with increasing age, more anxious and avoidant attachment was reported, except in Belgian adolescents where anxious and avoidant attachment did not differ over age. Focusing solely on the Vietnamese data, results revealed that the ECR-RC is a reliable measure to assess Vietnamese adolescents' anxious and avoidant attachment to both parents. Vietnamese adolescents did not differ in their levels of anxious attachment toward both parents but showed higher avoidant attachment to fathers compared to mothers. This document is copyrighted by the American Psychological Association or one of its allied publishers.This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.