CO2 snow cleaning of optics: curing the contamination problem

2000 ◽  
Author(s):  
Richard R. Zito
Keyword(s):  
Contamination Problem

An Attack on the Contamination Problem in the Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 368-368
Author(s):  
J. J. Kelsch ◽  
A. Holtz
Keyword(s):  
Electron Microscope ◽  
Pressure Gradient ◽  
Ionization Potential ◽  
Simple Solution ◽  
Specimen Surface ◽  
Contamination Rate ◽  
Local Pressure ◽  
High Ionization ◽  
Hydrocarbon Molecules ◽  
Contamination Problem

A simple solution to the serious problem of specimen contamination in the electron microscope is presented. This is accomplished by the introduction of clean helium into the vacuum exactly at the specimen position. The local pressure gradient thus established inhibits the migration of hydrocarbon molecules to the specimen surface. The high ionization potential of He permits the use of relatively large volumes of the gas, without interfering with gun stability. The contamination rate is reduced on metal samples by a factor of 10.

scholarly journals GUIDING FUTURE RESEARCH ON THE VALORISATION OF SHREDDER FINE RESIDUES: A REVIEW OF FOUR DECADES OF RESEARCH

Detritus ◽  
2019 ◽  
pp. 150-164 ◽  
Author(s):  
Tharaka Gunaratne ◽  
Joakim Krook ◽  
Mats Eklund ◽  
Hans Andersson
Keyword(s):  
Process Development ◽  
Future Research ◽  
Research Topics ◽  
Main Research ◽  
Systems Perspective ◽  
Material Characterisation ◽  
Micro Level ◽  
Substitute Material ◽  
The Individual ◽  
Contamination Problem

Millions of tonnes of shredder fines are generated and disposed of globally, despite compelling reasons for its recovery. The absence of a review of previous literature, however, makes it difficult to understand the underlying reasons for this. Thus, this study attempts to investigate and assess what, to what extent, and in what ways shredder fines have been addressed in previous research. In doing so, guidelines are drawn for future research to facilitate the valorisation (upgrading and recovery) of shredder fines. Previous research concerning shredder fines was identified with respect to three main research topics. The material characterisation studies are predominantly confined to the occurrence of metals due to their recovery and contamination potential. The process development studies have often undertaken narrowly conceived objectives of addressing one resource opportunity or contamination problem at a time. Consequently, the full recovery (the retrieval of valuable resources and the bulk-utilisation as substitute material) potential of shredder fines has been largely overlooked. The main limitation of policy and regulation studies is the absence of in-depth knowledge on the implications of governmental waste- and resource-policies (macro-level) on actors’ incentives and capacities (micro-level) for fines valorisation, which is necessary to understand the marketability of fines-derived resources. Undertaking a systems perspective is the key to recognising not only the different aspects within the individual research topics but also the inter-relations between them. It also facilitates the internalisation of the inter-relations into topical research.

scholarly journals Assessing Occupational Exposure to Surface Contaminants in Kuwaiti Educational Buildings

2019 ◽  
Vol 2 (3) ◽  
pp. 1
Author(s):  
Abdul-Salam Al-Temeemi ◽  
Jamal Al-Hubail ◽  
Ahmad Al-Khayat
Keyword(s):  
Architectural Design ◽  
Bacterial Contamination ◽  
Sampling Location ◽  
Contamination Level ◽  
E Coli ◽  
Surface Contaminants ◽  
Microbiological Testing ◽  
Stool Samples ◽  
The State Of Kuwait ◽  
Contamination Problem

The prevalence of surface contaminants, such as potentially harmful bacteria, within building environments in the State of Kuwait is not known.To the authors’ knowledge, this article is the frst of such a report. A total of 342 stool samples were collected from 46 secondary schools to evaluate indoor occurrences of E. coli bacteria within selected lavatory surfaces. After microbiological testing, the results for the spread of the E. coli bacteria were categorized by total count, sampling location dependency, contamination level comparison between genders, and lavatory fxtures (i.e. seat and squat toilets). The results revealed that 7 schools have a bacterial contamination problem, there is cross-contamination between surfaces in the lavatory stalls, the boys’ lavatories were less sanitary than the girls’, and that the squat-style toilets are more contaminated than the seat-style. The results suggest that there is signifcant risk of spread of bacterial infection among students via contaminated hands and surfaces in the lavatory area in some schools. Thus, this study emphasizes the need to improve environmental hygiene and enhanced sanitation in these schools. In addition, conclusions can be drawn as to the effectiveness of the janitorial staff employed by the schools and the effcacy of the cleaning regime used in the lavatories. Furthermore, based on the fndings, there are architectural design consequences as squat-style toilets might be excluded in lavatories designed for schools to be constructed in the future.

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