RESUMEN
Safety assessments and environmental impact statements for facilities require an estimation of airborne releases. Aerosols generated by accidents are being investigated to develop the source terms for these releases. A severe accidental release event could be a pressurized powder release. Pressurized powder release experiments performed in static air measured the mass airborne and particle size distribution of these aerosols as a function of source size and containment pressure. Both containment pressure and source size were significant in pressurized powder releases. Release in static air can be estimated using the relationships developed in this work. Weight percent of the source powder airborne ranged from approximately 2 to 24%. Mass median aerodynamic equivalent diameters of the airborne particles ranged from 5 to 19 microns. All of the pressurized releases produced a significant fraction of respirable particles 10 microns AED and less.
Asunto(s)
Accidentes de Trabajo , Contaminantes Atmosféricos/análisis , Compuestos de Uranio , Aerosoles , Contaminantes Radiactivos del Aire/análisis , Tamaño de la Partícula , Polvos , Presión , Titanio/análisis , Uranio/análisisRESUMEN
Safety assessments and environmental impact statements for facilities require an estimation of airborne releases from accidents. Aerosols generated by accidents are being investigated to develop the source terms for these releases. One example of a severe accidental release event is a pressurized liquid release. Pressurized liquid release experiments performed in static air measured the mass airborne as a function of source size and containment pressure. Pressurized releases with the containment breach above the liquid level were investigated. For this configuration, only containment pressure at the time of release was found to be a significant parameter. Releases in static air can be estimated using the relationships developed in this work. Weight percent of the airborne source ranged from 4 X 10(-4) to 0.15%. All of the pressurized releases produced a significant fraction of respirable particles.
Asunto(s)
Accidentes de Trabajo , Aerosoles/análisis , Contaminantes Atmosféricos/análisis , Fluoresceína , Fluoresceínas/análisis , Tamaño de la PartículaRESUMEN
A new apparatus for continuously detecting fluorescently labeled DNA fragments is based on infrared fluorescence technology. This technology combines state-of-the-art developments in chemistry, laser technology, and detection, while achieving improved reliability, sensitivity, and flexibility for applications including DNA sequencing. DNA molecules labeled with a novel infrared fluorophore are detected during electrophoresis using a scanning infrared fluorescence microscope. The microscope consists of a laser diode for exciting the fluorophore and a silicon avalanche photodiode for detecting the infrared emission. Optimum conditions for detection and throughput are obtained by adjusting electrophoresis, scanning and imaging parameters. Typical DNA sequencing runs (test templates) allow identification of over 500 bases per sample with greater than 99% accuracy.
Asunto(s)
ADN/química , Electroforesis en Gel de Poliacrilamida/instrumentación , Rayos Láser , Procesamiento de Señales Asistido por Computador , Secuencia de Bases , ADN de Cadena Simple/síntesis química , Procesamiento de Imagen Asistido por Computador , Microscopía Fluorescente , Datos de Secuencia Molecular , Estructura Molecular , Espectrofotometría Infrarroja/instrumentación , Moldes GenéticosRESUMEN
Near-infrared fluorescence provides a nonradioactive method of detection with high sensitivity and low background. An infrared fluorophore has been attached covalently to the nucleotide deoxyadenosine triphosphate (dATP) to provide a reagent for enzymatic labeling of various types of DNA molecules and for facilitating their detection with an automated DNA sequencing and analysis system. DNA sequencing reaction products can be labeled internally by performing limited polymerization utilizing infrared-labeled dATP (IR-dATP) as the sole source of adenine deoxynucleotide prior to a dideoxy-specific termination reaction. PCR products can be labeled fluorescently by the addition of limited quantities of IR-dATP to the amplification reaction. This latter strategy has been utilized for detection of short tandem repeat polymorphisms (STRPs) which are useful for gene mapping, genetic diagnostics, forensic analysis, and paternity testing. Restriction fragments can be labeled also by fill-in reactions of appropriate 5' overhangs. Diminutive amounts of such fluorescently labeled DNA molecules can be visualized rapidly and conveniently using infrared detection technology.