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Insights Into Emissions and Exposures From Use of Industrial-Scale Additive Manufacturing Machines
A.B. Stefaniak,A.R. Johnson,S. du Preez,D.R. Hammond,J.R. Wells,J.E. Ham,R.F. LeBouf,S.B. Martin Jr.,M.G. Duling,L.N. Bowers,A.K. Knepp,D.J. de Beer,J.L. du Plessis 한국산업안전보건공단 산업안전보건연구원 2019 Safety and health at work Vol.10 No.2
Background: Emerging reports suggest the potential for adverse health effects from exposure to emissions from some additive manufacturing (AM) processes. There is a paucity of real-world data on emissions from AM machines in industrial workplaces and personal exposures among AM operators. Methods: Airborne particle and organic chemical emissions and personal exposures were characterized using real-time and time-integrated sampling techniques in four manufacturing facilities using industrial-scale material extrusion and material jetting AM processes. Results: Using a condensation nuclei counter, number-based particle emission rates (ERs) (number/min) from material extrusion AM machines ranged from 4.1 1010 (Ultem filament) to 2.2 1011 [acrylonitrile butadiene styrene and polycarbonate filaments). For these same machines, total volatile organic compound ERs (mg/min) ranged from 1.9 104 (acrylonitrile butadiene styrene and polycarbonate) to 9.4 104 (Ultem). For the material jetting machines, the number-based particle ER was higher when the lid was open (2.3 1010 number/min) than when the lid was closed (1.5e5.5 109 number/min); total volatile organic compound ERs were similar regardless of the lid position. Low levels of acetone, benzene, toluene, and m,p-xylene were common to both AM processes. Carbonyl compounds were detected; however, none were specifically attributed to the AM processes. Personal exposures to metals (aluminum and iron) and eight volatile organic compounds were all below National Institute for Occupational Safety and Health (NIOSH)-recommended exposure levels. Conclusion: Industrial-scale AM machines using thermoplastics and resins released particles and organic vapors into workplace air. More research is needed to understand factors influencing real-world industrial- scale AM process emissions and exposures.
Insights Into Emissions and Exposures From Use of Industrial-Scale Additive Manufacturing Machines
Stefaniak, A.B.,Johnson, A.R.,du Preez, S.,Hammond, D.R.,Wells, J.R.,Ham, J.E.,LeBouf, R.F.,Martin, S.B. Jr.,Duling, M.G.,Bowers, L.N.,Knepp, A.K.,de Beer, D.J.,du Plessis, J.L. Occupational Safety and Health Research Institute 2019 Safety and health at work Vol.10 No.2
Background: Emerging reports suggest the potential for adverse health effects from exposure to emissions from some additive manufacturing (AM) processes. There is a paucity of real-world data on emissions from AM machines in industrial workplaces and personal exposures among AM operators. Methods: Airborne particle and organic chemical emissions and personal exposures were characterized using real-time and time-integrated sampling techniques in four manufacturing facilities using industrial-scale material extrusion and material jetting AM processes. Results: Using a condensation nuclei counter, number-based particle emission rates (ERs) (number/min) from material extrusion AM machines ranged from $4.1{\times}10^{10}$ (Ultem filament) to $2.2{\times}10^{11}$ [acrylonitrile butadiene styrene and polycarbonate filaments). For these same machines, total volatile organic compound ERs (${\mu}g/min$) ranged from $1.9{\times}10^4$ (acrylonitrile butadiene styrene and polycarbonate) to $9.4{\times}10^4$ (Ultem). For the material jetting machines, the number-based particle ER was higher when the lid was open ($2.3{\times}10^{10}number/min$) than when the lid was closed ($1.5-5.5{\times}10^9number/min$); total volatile organic compound ERs were similar regardless of the lid position. Low levels of acetone, benzene, toluene, and m,p-xylene were common to both AM processes. Carbonyl compounds were detected; however, none were specifically attributed to the AM processes. Personal exposures to metals (aluminum and iron) and eight volatile organic compounds were all below National Institute for Occupational Safety and Health (NIOSH)-recommended exposure levels. Conclusion: Industrial-scale AM machines using thermoplastics and resins released particles and organic vapors into workplace air. More research is needed to understand factors influencing real-world industrial-scale AM process emissions and exposures.
Controlling attosecond angular streaking with second harmonic radiation.
Hammond, T J,Kim, Kyung Taec,Zhang, Chunmei,Villeneuve, D M,Corkum, P B Optical Society of America 2015 Optics letters Vol.40 No.8
<P>High harmonic generation, which produces a coherent burst of radiation every half cycle of the driving field, has been combined with ultrafast wavefront rotation to create a series of spatially separated attosecond pulses, called the attosecond lighthouse. By adding a coherent second harmonic beam with polarization parallel to the fundamental, we decrease the generating frequency from twice per optical cycle to once. The increased temporal separation increases the pulse contrast. By scanning the carrier envelope phase, we see that the signal is 2π periodic.</P>
Attosecond pulses measured from the attosecond lighthouse
Hammond, T. J.,Brown, Graham G.,Kim, Kyung Taec,Villeneuve, D. M.,Corkum, P. B. Nature Publishing Group, a division of Macmillan P 2016 Nature photonics Vol.10 No.3
<P>The attosecond lighthouse is a method of using ultrafast wavefront rotation with high-harmonic generation to create a series of coherent, spatially separated attosecond pulses. Previously, temporal measurements by photoelectron streaking characterized isolated attosecond pulses created by manipulating the single-atom response(1-4). The attosecond lighthouse, in contrast, generates a series of pulses that spatially separate and become isolated by propagation. Here, we show that ultrafast wavefront rotation maintains the single-atom response (in terms of temporal character) of an isolated attosecond pulse over two octaves of bandwidth. Moreover, we exploit the unique property of the attosecond lighthouse-the generation of several isolated pulses-to measure the three most intense pulses. These pulses each have a unique spectrum and spectral phase.</P>