Monitoring and Analysis of Solvent Emissions from Metal Cleaning Processes for Practical Process Improvement

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Emi Kikuchi*, Yasunori Kikuchi and Masahiko Hirao

Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo, Japan?* Author to whom correspondence should be addressed. Tel: +81-3-5841-7227; fax: +81-3-5841-6876; e-mail: e-kikuchi{at}pse.t.u-tokyo.ac.jp Received September 12, 2011. Accepted November 8, 2011. Objectives: Industrial cleaning processes are a major source of emissions of chlorinated organic solvents in Japan. Solvent emission mechanisms from metal cleaning processes were analysed to support process improvement aimed at emission reductions.

Methods: The amounts of solvents directly emitted from a washing machine and solvents taken out by metal parts to be cleaned were measured in laboratory experiments using an industrial washing machine. Direct emissions to a local ventilation system and to the workplace were analysed, while several process conditions were changed. The drying rate of solvents on surfaces was analysed for seven metal parts to clarify the effects of their materials and shape. Results: The results for direct solvent emissions show that solvents emitted because of the movement of metal parts inside a washing machine can be mainly exhausted through a local ventilation system, while the operation of an ultrasonic device can increase solvent diffusion to the workplace. Lowering the cooling water temperature can be effective in avoiding such solvent diffusion to the workplace. The results also show that the heat capacity and shape complexity of metal parts can affect the drying rate of solvents on their surfaces. Conclusions: Analysis of the results shows the effectiveness of using a local ventilation system and cooling pipes in controlling solvent emissions for several work tasks. The minimum time required to dry all solvents on the surface of metal parts was also estimated. Analyses of the emission mechanisms in this study clarified the major factors in solvent emissions and the effectiveness of process modifications for emission reductions. The findings are applicable to practical process improvement aimed at emission reductions in cleaning sites. © The Author 2012. Published by Oxford University Press on behalf of the British Occupational Hygiene SocietyThis ArticleAnn Occup Hyg (2012) 56 (7): 829-842. doi: 10.1093/annhyg/mer115 First published online: December 19, 2011 Current Issue
Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.

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Monitoring and Analysis of Solvent Emissions from Metal Cleaning Processes for Practical Process Improvement

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Emi Kikuchi*, Yasunori Kikuchi and Masahiko Hirao

Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo, Japan?* Author to whom correspondence should be addressed. Tel: +81-3-5841-7227; fax: +81-3-5841-6876; e-mail: e-kikuchi{at}pse.t.u-tokyo.ac.jp Received September 12, 2011. Accepted November 8, 2011. Objectives: Industrial cleaning processes are a major source of emissions of chlorinated organic solvents in Japan. Solvent emission mechanisms from metal cleaning processes were analysed to support process improvement aimed at emission reductions.

Methods: The amounts of solvents directly emitted from a washing machine and solvents taken out by metal parts to be cleaned were measured in laboratory experiments using an industrial washing machine. Direct emissions to a local ventilation system and to the workplace were analysed, while several process conditions were changed. The drying rate of solvents on surfaces was analysed for seven metal parts to clarify the effects of their materials and shape. Results: The results for direct solvent emissions show that solvents emitted because of the movement of metal parts inside a washing machine can be mainly exhausted through a local ventilation system, while the operation of an ultrasonic device can increase solvent diffusion to the workplace. Lowering the cooling water temperature can be effective in avoiding such solvent diffusion to the workplace. The results also show that the heat capacity and shape complexity of metal parts can affect the drying rate of solvents on their surfaces. Conclusions: Analysis of the results shows the effectiveness of using a local ventilation system and cooling pipes in controlling solvent emissions for several work tasks. The minimum time required to dry all solvents on the surface of metal parts was also estimated. Analyses of the emission mechanisms in this study clarified the major factors in solvent emissions and the effectiveness of process modifications for emission reductions. The findings are applicable to practical process improvement aimed at emission reductions in cleaning sites. © The Author 2012. Published by Oxford University Press on behalf of the British Occupational Hygiene SocietyThis ArticleAnn Occup Hyg (2012) 56 (7): 829-842. doi: 10.1093/annhyg/mer115 First published online: December 19, 2011 Current Issue
Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.

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Process controlling night vision clarifled

ScienceDaily (Oct. 17, 2012) — On the road at night or on a tennis court at dusk, the eye can be deceived. Vision is not as sharp as in the light of day, and detecting a bicyclist on the road or a careening tennis ball can be tough.

New research reveals the key chemical process that corrects for potential visual errors in low-light conditions. Understanding this fundamental step could lead to new treatments for visual deficits, or might one day boost normal night vision to new levels.

Like the mirror of a telescope pointed toward the night sky, the eye's rod cells capture the energy of photons ? the individual particles that make up light. The interaction triggers a series of chemical signals that ultimately translate the photons into the light we see.

The key light receptor in rod cells is a protein called rhodopsin. Each rod cell has about 100 million rhodopsin receptors, and each one can detect a single photon at a time.

Scientists had thought that the strength of rhodopsin's signal determines how well we see in dim light. But UC Davis scientists have found instead that a second step acts as a gatekeeper to correct for rhodopsin errors. The result is a more accurate reading of light under dim conditions.

A report on their research appears in the October issue of the journal Neuron.

Individual rhodopsin errors are relatively small in magnitude ? on the order of a few hundredths of a second ? but even this much biological noise can affect how well the signal gets transmitted to the rest of the brain, the researchers said.

The gatekeeper protects us from "seeing" more light than is actually there ? a misreading that would have endangered an ice-age hunter, as it would a driver at dusk today. The correction may prevent the photon receptor from swamping the intricate chemical apparatus that leads to accurate light perception.

"The rhodopsin receptor is the site where physics meets biology ? where a photon of light from the physical world must get interpreted for the nervous system," said Marie Burns, professor of ophthalmology and vision science at UC Davis School of Medicine and lead author of the study. "Biology is messy. Rhodopsin does a remarkable but not perfect job."

Burns and her colleagues studied rod cells in the laboratory and discovered that calcium plays the gatekeeper role.

They found that rhodopsin activity changed calcium levels in the cells and that over-active rhodopsins changed calcium levels at a faster rate than normal. This faster change led calcium to trigger a series of chemical steps to counter the over-active rhodopsin signal by producing an equal and opposite signal, thereby correcting false information before it gets sent on to the rest of the visual system.

They uncovered this fundamental new level of control by measuring how long individual rhodopsin receptors remained active in response to flashes of light, and then determining how much calcium's gatekeeping function modified the rhodopsin signals.

"Basic research like ours often doesn't translate to immediate clinical treatments for known diseases, but understanding fundamental processes has long-term significance," Burns said. "In the case of our research, this understanding can prove essential for progress on a range of vision deficits that are currently poorly understood and untreatable."

Colleagues in the research and co-authors on the paper include Owen Gross, a former doctoral student at UC Davis who is now at Oregon Health Sciences University, and Edward N. Pugh Jr., a professor in the Department of Cell Biology and Human Anatomy and Department of Physiology and Membrane Biology at the UC Davis School of Medicine.

The research was funded with a grant from the National Eye Institute.

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The above story is reprinted from materials provided by University of California - Davis Health System.

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Journal Reference:

Owen P. Gross, Edward N. Pugh, Marie E. Burns. Calcium Feedback to cGMP Synthesis Strongly Attenuates Single-Photon Responses Driven by Long Rhodopsin Lifetimes. Neuron, 2012; 76 (2): 370 DOI: 10.1016/j.neuron.2012.07.029

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

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Monitoring and Analysis of Solvent Emissions from Metal Cleaning Processes for Practical Process Improvement

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Emi Kikuchi*, Yasunori Kikuchi and Masahiko Hirao

Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo, Japan?* Author to whom correspondence should be addressed. Tel: +81-3-5841-7227; fax: +81-3-5841-6876; e-mail: e-kikuchi{at}pse.t.u-tokyo.ac.jp Received September 12, 2011. Accepted November 8, 2011. Objectives: Industrial cleaning processes are a major source of emissions of chlorinated organic solvents in Japan. Solvent emission mechanisms from metal cleaning processes were analysed to support process improvement aimed at emission reductions.

Methods: The amounts of solvents directly emitted from a washing machine and solvents taken out by metal parts to be cleaned were measured in laboratory experiments using an industrial washing machine. Direct emissions to a local ventilation system and to the workplace were analysed, while several process conditions were changed. The drying rate of solvents on surfaces was analysed for seven metal parts to clarify the effects of their materials and shape. Results: The results for direct solvent emissions show that solvents emitted because of the movement of metal parts inside a washing machine can be mainly exhausted through a local ventilation system, while the operation of an ultrasonic device can increase solvent diffusion to the workplace. Lowering the cooling water temperature can be effective in avoiding such solvent diffusion to the workplace. The results also show that the heat capacity and shape complexity of metal parts can affect the drying rate of solvents on their surfaces. Conclusions: Analysis of the results shows the effectiveness of using a local ventilation system and cooling pipes in controlling solvent emissions for several work tasks. The minimum time required to dry all solvents on the surface of metal parts was also estimated. Analyses of the emission mechanisms in this study clarified the major factors in solvent emissions and the effectiveness of process modifications for emission reductions. The findings are applicable to practical process improvement aimed at emission reductions in cleaning sites. © The Author 2012. Published by Oxford University Press on behalf of the British Occupational Hygiene SocietyThis ArticleAnn Occup Hyg (2012) 56 (7): 829-842. doi: 10.1093/annhyg/mer115 First published online: December 19, 2011 Current Issue
Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.

View the original article here

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