Space programs summary no. 37-61, volume 1 for the period 1 November - 31 December 1969. Flight projects

Mariner Mars 1969 project, Mariner Mars 1971 project, and Viking 1973 project - research and advancement developmen

A Gas Chromatographic Microsystem for Volatile Organic Compounds: Critical Components, Chemometric Algorithms, and a Laboratory Prototype for Workplace Exposure Monitoring.

Current methods for evaluating worker exposures to mixtures of airborne volatile organic compounds (VOC) entail the collection of breathing-zone air samples, typically over several hours, followed by off-site laboratory analysis. Performing measurements with a direct-reading instrument worn by the worker would improve the quality of exposure data by capturing exposure dynamics within a shift. This dissertation describes work directed toward the development of a wearable, battery-powered instrument containing a gas chromatographic microsystem (mGC) made from Si-microfabricated components, which offers the potential for quantitative determinations of multiple VOCs. The core components of our μGC are a dual-adsorbent micro-preconcentrator-focuser (μPCF), a dual-μcolumn separation module, and a μsensor-array detector. The latter consists of 4-8 chemiresistors (CR) coated with monolayer-protected Au nanoparticles (MPN), which collectively yield partially selective response patterns that enhance the recognition/discrimination of VOCs. In phase one of this research we adapted a multivariate curve resolution method to the problem of differentiating and quantifying the components of chromatographically unresolved VOCs on the basis of their CR-array response patterns. Results showed that the rank of a given composite peak could be correctly determined in most cases, but, due to the low dimensionality of the array, the accuracies of recognition and quantification were less than optimal in most cases. Next, we optimized the mPCF for the capture and injection of VOCs within a specified vapor pressure range at concentrations near their respective occupational exposure limits. Using a few mg each of two high-surface-area graphitized carbons, conditions were established to permit exhaustive selective trapping of VOCs in sample volumes sufficient to meet required detection limits of all mixture components, and efficient, focused thermal desorption/injection to facilitate rapid, high-resolution separations of all components. Phase three entailed the design, assembly, and characterization of a first-generation laboratory prototype μGC. Component-level and system-level characterizations yielded a set of operating conditions suitable for numerous possible workplace exposure scenarios. The reproducible analysis of mixtures of VOCs at relevant concentrations was demonstrated; the combination of retention times and response patterns provided the identity and quantity of all analytes. Results have provided critical guidance for the next-generation wearable μGC.PhDEnvironmental Health SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133310/1/genevier_1.pd

A Micro-Analytical System for Complex Vapor Mixtures - Development and Application to Indoor Air Contaminants.

This dissertation concerns the development of two fully integrated, automatically controlled, field-deployable Si-microfabricated gas chromatograph (µGC) prototypes, and their application to indoor-air monitoring of trace-level trichloroethylene (TCE) vapor concentrations. Each µGC prototype has a pre-trap and a partially selective high-volume sampler of conventional design, a micromachined-Si focuser for injection, dual micromachined-Si columns for separation, and an integrated array of four microscale chemiresistors with functionalized gold-nanoparticle interface films for detection. Scrubbed ambient air is used as the carrier gas. Operating conditions and control settings are user-defined through a laptop computer, providing real-time data display and continuous unattended operation. A meso-scale GC employing the same detector technology as in the µGC prototypes was adapted for the same application, and the laboratory results obtained were used to guide the design and operating conditions of the µGCs. Application of a multivariate curve resolution method for deconvoluting microsensor array responses from partially overlapping interferences was also demonstrated. The µGC prototypes were characterized in the laboratory and then field tested in Utah in a house with active TCE vapor intrusion. In the laboratory, the separation of TCE from 45 other VOCs in < 60 sec, unique sensor-array response patterns, and accurate quantification of as little as 0.12 parts per billion (ppb) of TCE were demonstrated. In the field, the projected single-microsensor detection limit was 0.052 ppb for an 8-L air sample collected and analyzed in 20 min. Above the mitigation action level (MAL) of 2.3 ppb for the field-test site, accurate TCE determinations were achieved in the presence of up to 52 documented background VOCs. Below the MAL, positive biases were observed, which are attributable to background VOCs that were unresolvable chromatographically or by analysis of the sensor-array response patterns. Spatial and temporal variations in TCE concentrations, ranging from 0.23 to 56 ppb, provided by the prototypes were in good agreement with reference method values. This is the first study to validate the performance of a µGC in the field. Results demonstrate that µGC technology could provide selective, trace-level, on-site determinations of VOCs in numerous applications relevant to occupational and environmental exposure assessment.Ph.D.Environmental Health SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91391/1/airbuff_1.pd

Single- and Multi-Transducer Arrays Employing Nanoparticle Interface Layers as Vapor Detectors for a Microfabricated Gas Chromatograph.

This body of research focuses on improving microsensor arrays used as detectors in Si-microfabricated gas chromatographs (µGC) for the determination of volatile organic compounds (VOCs). By means of such improvements, µGC technology should find wider application in homeland security, disease diagnosis, and environmental monitoring. The microsensors considered here all employ thiolate-monolayer-protected gold nanoparticles (MPN) as vapor sorptive interface layers. The central hypothesis is that by altering the MPN ligand, core size, and/or the underlying transducer, the diversity of responses to VOCs provided by microsensor arrays with MPN interfaces can be improved. The first study evaluated a single transducer (ST) array of MPN-coated chemiresistors (CR) as a µGC detector for three semi-volatile markers of the explosive 2,4,6-trinitrotoluene in the presence of alkane interferences of similar volatility. The effects of flow rate and temperature on chromatographic resolution, sensitivity, and limits of detection (LOD) were assessed. Under optimized conditions, a complete analysis required 95%). These types of sensor arrays can enhance the vapor discrimination of sorption-based detectors utilized in µGC technology, making the analysis of complex VOC mixtures possible.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111430/1/lkamos_1.pd

A study to examine the feasibility of using surface penetrators for mineral exploration

The feasibility of using penetrators in earth applications is examined. Penetrator applications in exploration for mineral resources only is summarized. Instrumentation for future penetrators is described. Portions of this report are incorporated into a more extensive report examining other penetrator applications in exploration for fossil fuels, geothermal resources, and in environmental and engineering problems, which is to be published as a NASA technical publication

MEMS Devices for Miniaturized Gas Chromatography

In the era of the Internet of Things, the need for mobile devices able to analyze accurately real samples with sometimes very small volumes is a must. Gas chromatography (GC) is a common laboratory technique widely used for analyzing semi-volatile and volatile compounds. However, this technique is not suitable to be used outside labs. The development of micro-machined processes encouraged the development of miniaturized gas chromatographs. This chapter focuses on the recent development in the field of miniaturized gas chromatography and its component up to the present in various fields of analyses

Review of Portable and Low-Cost Sensors for the Ambient Air Monitoring of Benzene and Other Volatile Organic Compounds

This article presents a literature review of sensors for the monitoring of benzene in ambient air and other volatile organic compounds. Combined with information provided by stakeholders, manufacturers and literature, the review considers commercially available sensors, including PID-based sensors, semiconductor (resistive gas sensors) and portable on-line measuring devices as for example sensor arrays. The bibliographic collection includes the following topics: sensor description, field of application at fixed sites, indoor and ambient air monitoring, range of concentration levels and limit of detection in air, model descriptions of the phenomena involved in the sensor detection process, gaseous interference selectivity of sensors in complex VOC matrix, validation data in lab experiments and under field conditions

Site investigation techniques for DNAPL source and plume zone characterisation

Establishing the location of the Source Area BioREmediation (SABRE) research cell was a primary objective of the site characterisation programme. This bulletin describes the development of a two-stage site characterisation methodology that combined qualitative and quantitative data to guide and inform an assessment of dense nonaqueous phase liquid (DNAPL) distribution at the site. DNAPL site characterisation has traditionally involved multiple phases of site investigation, characterised by rigid sampling and analysis programmes, expensive mobilisations and long decision-making timeframes (Crumbling, 2001a) , resulting in site investigations that are costly and long in duration. Here we follow the principles of an innovative framework, termed Triad (Crumbling, 2001a, 2001b; Crumbling et al., 2001, Crumbling et al. 2003), which describes a systematic approach for the characterisation and remediation of contaminated sites. The Triad approach to site characterisation focuses on three main components: a) systematic planning which is implemented with a preliminary conceptual site model from existing data. The desired outcomes are planned and decision uncertainties are evaluated; b) dynamic work strategies that focus on the need for flexibility as site characterisation progresses so that new information can guide the investigation in real-time and c) real-time measurement technologies that are critical in making dynamic work strategies possible. Key to this approach is the selection of suitable measurement technologies, of which there are two main categories (Crumbling et al., 2003). The first category provides qualitative, dense spatial data, often with detection limits over a preset value. These methods are generally of lower cost, produce real-time data and are primarily used to identify site areas that require further investigation. Examples of such "decisionquality" methods are laser induced fluorescence (Kram et al., 2001), membrane interface probing (McAndrews et al., 2003) and cone penetrometer testing (Robertson, 1990), all of which produce data in continuous vertical profiles. Because these methods are rapid, many profiles can be generated and hence the subsurface data density is greatly improved. These qualitative results are used to guide the sampling strategy for the application of the second category of technologies that generate quantitative, precise data that have low detection limits and are analyte-specific. These methods tend to be high cost with long turnaround times that preclude on-site decision making, hence applying them to quantify rather than produce a conceptual model facilitates a key cost saving. Examples include instrumental laboratory analyses such as soil solvent extractions (Parker et al., 2004)and water analyses (USEPA, 1996). Where these two categories of measurement technologies are used in tandem, a more complete and accurate dataset is achieved without additional site mobilisations. The aim of the site characterisation programme at the SABRE site was to delineate the DNAPL source zone rapidly and identify a location for the in situ research cell. The site characterisation objectives were to; a) test whether semi-quantitative measurement techniques could reliably determine geological interfaces, contaminant mass distribution and inform the initial site conceptual model; and b) quantitatively determine DNAPL source zone distribution, guided by the qualitative site conceptual model

JRU METROFOOD-MK AS A PART OF THE EUROPEAN RESEARCH INFRASTRUCTURE FOR PROMOTING METROLOGY IN FOOD AND NUTRITION

The METROFOOD-RI is European research infrastructure for promoting metrology in food and nutrition. This infrastructure is aimed to promote scientific excellence in the field of food quality and safety. JRU METROFOOD-MK is Joint Research Unit i.e. Macedonian Node which belongs to METROFOOD-MK infrastructure and consisted of two institutions, Institute of Public Health (IJZRSM) and Faculty of Agricultural Sciences and Food - Skopje (FASF). The METROFOOD-RIincludes physical infrastructure (P-RI) and electronic infrastructure (e-RI). The P-RI covers facilities for realization of different analyses related to food quality and safety such as: contaminants and ecotoxicology, food quality control, trace elements analysis, chemical analysis of primary agricultural and processed products. The e-RI represents a state of the art web platform enabling sharing and integrating information and data on availability of metrological tools for food analysis. METROFOOD-RI will be of great scientific importance for following user categories: researchers, policy makers, food inspection and control experts and organizations, food business operators and citizens