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At least 163 records · Page 9

Cleanroom Contaminant Monitor

Under a Small Business Innovation Research (SBIR) contract from Kennedy Space Center (KSC), Femtometrics, Inc. developed the Real-Time Non-Volatile Residue (NVR) monitor. Criteria established by KSC called for a technology that could regulate the accumulation of nonvolatile residues in cleanroom environments. The company accommodated the Center's need with an advanced, highly sensitive surface acoustic wave (SAW) microsensor capable of detecting sub-monolayer deposition in cleanrooms where aerospace systems are assembled. Years earlier, Femtometrics responded to and received SBIR contracts from Langley Research Center for highly sensitive aerosol detectors for environmental researchers. Stimulated by the SBIR wins, the company set about to develop the SAW resonator technology. A new type of sensor has evolved from the research, one that has the ability to measure a range of chemical vapors by applying chemical-specific coating on the sensing surface. Commercial applications of the Real-Time NVR include Class 1 cleanrooms at semiconductor and hard-disk manufacturing plants.

Source record↗

More on Ru Endemic Isotope Anomalies in Meteorites

We reported last year on endemic isotope anomalies for Ru in iron meteorites, pallasites, ordinary chondrites, and on a whole-rock sample of Allende. We have extended the Ru measurements to more meteorites, to refractory Ca-Al-rich inclusions (CAI) from Allende, and to a whole rock sample of Murchison (CM2). In a companion abstract we report on new measurements for the Mo isotopes, in some of the same samples. There has been a renewed interest in searching for isotope anomalies in this nuclide region, as Ru and Mo include many isotopes from r-, s-, and p-process nucleosynhesis. Furthermore, the Ru and Mo p-process isotopes show atypically high abundances, which have been hard to explain through the standard nucleosynthetic processes. Effects are possible in Ru-98 and Ru-99 from Tc-98 (with a poorly known t(sub 1/2)=4.2 to 10Ma) and from Tc-99 (t(sub 1/2)=0.21Ma). Natural Tc is now extinct on Earth due to the short half-lives, but may have been present in the early solar system. Both radiogenic and general isotope anomalies are important in understanding the processes for the formation of the early solar system. The current emphasis on Ru and Mo is also the result of the development of Negative-ion Thermal Ionization Mass Spectrometry and of Multiple-Collector, Inductively-Coupled-Mass-Spectrometry. We have also developed specific chemical siparation techniques for Ru, which eliminated mass interference effects.

Papanastassiou, D. A.↗

In vitro evolution of nucleic acids

The author reviews recent published reports of in vitro selection and evolution of nucleic acids. These nucleic acids will bind to a target ligand or catalyze a specific chemical reaction. The terms aptamers and systematic evolution of ligands by exponential enrichment (SELEX) are explained. The review focuses on protein binders, small molecule binders, and ribozymes obtained by directed evolution. The reference list identifies articles of special or outstanding interest.

Review↗

Crop Surveillance Demonstration Using a Near-Daily MODIS Derived Vegetation Index Time Series

Effective response to crop disease outbreaks requires rapid identification and diagnosis of an event. A near-daily vegetation index product, such as a Normalized Difference Vegetation Index (NDVI), at moderate spatial resolution may serve as a good method for monitoring quick-acting diseases. NASA s Moderate Resolution Imaging Spectroradiometer (MODIS) instrument flown on the Terra and Aqua satellites has the temporal, spatial, and spectral properties to make it an excellent coarse-resolution data source for rapid, comprehensive surveillance of agricultural areas. A proof-of-concept wide area crop surveillance system using daily MODIS imagery was developed and tested on a set of San Joaquin cotton fields over a growing season. This area was chosen in part because excellent ground truth data were readily available. Preliminary results indicate that, at least in the southwestern part of the United States, near-daily NDVI products can be generated that show the natural variations in the crops as well as specific crop practices. Various filtering methods were evaluated and compared with standard MOD13 NDVI MODIS products. We observed that specific chemical applications that produce defoliation, which would have been missed using the standard 16-day product, were easily detectable with the filtered daily NDVI products.

McKellip, Rodney↗

The devil that we know: lead (Pb) replacement policies under conditions of scientific uncertainty

Engineering and economic considerations are typical driving forces behind the selection of specific chemicals used in the manufacture of consumer products. Only recently has post-consumer environmental impact become part of the major considerations during the initial phases of product design. Therefore, reactive, rather than proactive strategies have dominated the consideration of environmental and health issues in product design.

Pb-free↗

Compositions of Spherules and Rock Surfaces at Meridiani

The Alpha Particle X-ray Spectrometers (APXS) on the Mars Exploration Rovers (MER) have proven extremely valuable for analyzing rocks and soils on the surface of Mars. The precision of their compositional measurements has been shown to be phenomenal through analyses of the compositionally very uniform Meridiani soils. Through combined use of the rock abrasion tool (RAT) and the analytical instruments on the in-situ deployment device (IDD), analyses of the interiors of fine-grained and texturally uniform rocks with surfaces ground flat have been made under conditions that are nearly ideal for this mode of analysis. The APXS has also been used frequently to analyze materials whose characteristics, surface morphologies, and sample-detector geometries are less than ideal, but the analyses of which are nonetheless very useful for understanding the makeup of the target materials. Such targets include undisturbed rocks with irregular and sometimes coated surfaces and mixed targets such as soils that include fine-grained components as well as coarse grains and pieces of rocks. Such target materials include the well known hematite-rich concretions, referred to as blueberries because of their multispectral color, size, and mode of occurrence. In addition to non-ideal target geometry, such mixed materials also present a heterogeneous target in terms of density. These irregularities violate the assumptions commonly associated with analyses done in the laboratory to achieve the highest possible accuracy. Here we acknowledge the irregularities and we examine the inferences drawn from specific chemical trends obtained on imperfect targets in light of one of the potential pitfalls of natural materials on the surface of Mars, namely thin dust coatings.

Mittlefehldt, David W.↗

Molecular Dynamics Simulations of Adhesion at Epoxy Interfaces

The effect of moisture on adhesives used in aerospace applications can be modeled with chemically specific techniques such as molecular dynamics simulation. In the present study, the surface energy and work of adhesion are calculated for epoxy surfaces and interfaces, respectively, by using molecular dynamics simulation. Modifications are made to current theory to calculate the work of adhesion at the epoxy-epoxy interface with and without water. Quantitative agreement with experimental values is obtained for the surface energy and work of adhesion at the interface without water. The work of adhesion agrees qualitatively with the experimental values for the interface with water: the magnitude is reduced 15% with respect to the value for the interface without water. A variation of 26% in the magnitude is observed depending on the water configuration at a concentration of 1.6 wt%. The methods and modifications to the method that are employed to obtain these values are expected to be applicable for other epoxy adhesives to determine the effects of moisture uptake on their work of adhesion.

Frankland, Sarah-Jane V.↗

NASA Tech Briefs, May 2008

Topics covered inclde: Deployable Wireless Camera Penetrators; Hand-Held Units for Short-Range Wireless Biotelemetry; Wearable Wireless Telemetry System for Implantable BioMEMS Sensors; Electronic Escape Trails for Firefighters; Architecture for a High-to-Medium-Voltage Power Converter; 24-Way Radial Power Combiner/Divider for 31 to 36 GHz; Three-Stage InP Submillimeter-Wave MMIC Amplifier; Fast Electromechanical Switches Based on Carbon Nanotubes; Solid-State High-Temperature Power Cells; Fast Offset Laser Phase-Locking System; Fabricating High-Resolution X-Ray Collimators; Embossed Teflon AF Laminate Membrane Microfluidic Diaphragm Valves; Flipperons for Improved Aerodynamic Performance; System Estimates Radius of Curvature of a Segmented Mirror; Refractory Ceramic Foams for Novel Applications; Self-Deploying Trusses Containing Shape-Memory Polymers; Fuel-Cell Electrolytes Based on Organosilica Hybrid Proton Conductors; Molecules for Fluorescence Detection of Specific Chemicals; Cell-Detection Technique for Automated Patch Clamping; Redesigned Human Metabolic Simulator; Compact, Highly Stable Ion Atomic Clock; LiGa(OTf)(sub 4) as an Electrolyte Salt for Li-Ion Cells; Compact Dielectric-Rod White-Light Delay Lines; Single-Mode WGM Resonators Fabricated by Diamond Turning; Mitigating Photon Jitter in Optical PPM Communication; MACOS Version 3.31; Fiber-Optic Determination of N2, O2, and Fuel Vapor in the Ullage of Liquid-Fuel Tanks; Spiking Neurons for Analysis of Patterns; Symmetric Phase-Only Filtering in Particle-Image Velocimetry; Efficient Coupler for a Bessel Beam Dispersive Element; and Attitude and Translation Control of a Solar Sail Vehicle.

Source record↗

Calculation of Oxygen Fugacity in High Pressure Metal-Silicate Experiments and Comparison to Standard Approaches

Calculation of oxygen fugacity in high pressure and temperature experiments in metal-silicate systems is usually approximated by the ratio of Fe in the metal and FeO in the silicate melt: (Delta)IW=2*log(X(sub Fe)/X(sub FeO)), where IW is the iron-wustite reference oxygen buffer. Although this is a quick and easy calculation to make, it has been applied to a huge variety of metallic (Fe- Ni-S-C-O-Si systems) and silicate liquids (SiO2, Al2O3, TiO2, FeO, MgO, CaO, Na2O, K2O systems). This approach has surely led to values that have little meaning, yet are applied with great confidence, for example, to a terrestrial mantle at "IW-2". Although fO2 can be circumvented in some cases by consideration of Fe-M distribution coefficient, these do not eliminate the effects of alloy or silicate liquid compositional variation, or the specific chemical effects of S in the silicate liquid, for example. In order to address the issue of what the actual value of fO2 is in any given experiment, we have calculated fO2 from the equilibria 2Fe (metal) + SiO2 (liq) + O2 = Fe2SiO4 (liq).

Righter, K.↗

Second-Generation Electronic Nose

A report discusses the second generation of the JPL Electronic Nose (ENose), an array of 32 semi-specific chemical sensors used as an event monitor to identify and quantify contaminants released into breathing air by leaks or spills. It is designed to monitor the environment for changes in air quality, and is trained to identify and quantify selected chemical species at predetermined concentrations, ranging from sub-ppm to ppth. This system has improved reproducibility for making matched arrays, allowing use of data analysis software with minimal recalibration on sensor set replacement. The Second Generation (SG) ENose is a follow-up to the first JPL Electronic Nose that was tested on an earlier space shuttle mission (STS-95). Improvements have been made to the hardware, sensor materials, and data analysis software.

Homer, Margie↗

Spacecraft Water Exposure Guidelines for Selected Contaminants

The International Space Station is a closed and complex environment, so some contamination of its internal atmosphere and water system is expected. To protect space crews from contaminants in potable and hygiene water, the National Aeronautics and Space Administration (NASA) requested that the National Research Council (NRC) provide guidance on how to develop water exposure guidelines and review NASA s development of the exposure guidelines for specific chemicals. NASA selects water contaminants for which spacecraft water exposure guidelines (SWEGs) will be established; this involves identifying toxicity effects relevant to astronauts and calculating exposure concentrations on the basis of those end points. SWEGs are established for exposures of 1, 10, 100, and 1,000 days. This report is the second volume in the series, Spacecraft Water Exposure Guidelines for Selected Chemicals. SWEG reports for acetone, alkylamines, ammonia, barium, cadmium, caprolactam, formate, formaldehyde, manganese, total organic carbon, and zinc are included in this report. The committee concludes that the SWEGs developed for these chemicals are scientifically valid based on the data reviewed by NASA and are consistent with the NRC (2000) report, Methods for Developing Spacecraft Water Exposure Guidelines. SWEG reports for additional chemicals will be presented in a subsequent volume.

Source record↗

JPL Electronic Nose: From Sniffing Brain Cancer to Trouble in Space

What Is An Electronic Nose? An array of non-specific chemical sensors, controlled and analyzed electronically, which mimics the action of the mammalian nose by recognizing patterns of response. An Enose: (1.) ENose measures background resistance in each sensor and establishes a baseline. (2.) Contaminant comes in contact with sensors on the sensing head. (3.) The sensing films, change physical properties, such as thickness or color, as air composition changes. (4.) Sensor response is recorded by a computer, the change in resistance is computed, and the distributed response pattern of the sensor array is used to identify gases and mixtures of gases. (5. Responses of the sensor array are analyzed and quantified using software developed for the task.

chemical sensing↗

Measuring Total and Germinable Spore Populations

It has been shown that bacterial endospores can be enumerated using a microscopy based assay that images the luminescent halos from terbium ions bound to dipicolinic acid, a spore specific chemical marker released upon spore germination. Further development of the instrument has simplified it towards automation while at the same time improving image quality. Enumeration of total spore populations has also been developed allowing measurement of the percentage of viable spores in any population by comparing the germinable/culturable spores to the total. Percentage viability will allow a more quantitative comparison of the ability of spores to survive across a wide range of extreme environments.

microbial life↗

Particle Capture Devices and Methods of Use Thereof

The present invention provides a device and methods of use thereof in microscale particle capturing and particle pairing. This invention provides particle patterning device, which mechanically traps individual particles within first chambers of capture units, transfer the particles to second chambers of opposing capture units, and traps a second type of particle in the same second chamber. The device and methods allow for high yield assaying of trapped cells, high yield fusion of trapped, paired cells, for controlled binding of particles to cells and for specific chemical reactions between particle interfaces and particle contents. The device and method provide means of identification of the particle population and a facile route to particle collection.

Voldman, Joel↗

Bonding to Bulk Metallic Glass using Aerospace-Grade Structural Adhesive

Bulk metallic glasses (BMGs) are non-crystalline metals with growing applications in aerospace. Due to their amorphous nature, BMGs generally exhibit stronger mechanical properties than most crystalline alloys and are more corrosion resistant. The limited reactivity of a corrosion resistant surface may explain the difficulty in establishing robust bonds to certain adhesives, especially commonly used structural adhesives for aerospace applications. Here, an amine cured aerospace adhesive was used for bonding an iron-nickel based BMG satellite component. Various types of processes were explored to avoid adhesive failure and increase bond strength. It was found that the BMG required specific chemical derivatization of the metal surface in order to achieve cohesive failure. Surface analysis was used to determine the mechanisms of adhesion enhancement. The process was optimized to maximize bond strength. This work helps explain the difficulties in bonding BMG materials and provides strategies for design of future bonded BMG components.

Roberts, Rose↗

Enabling Mission Flexibility to Battery Driven Deep Space Endeavors With Generalized Battery-Health-Monitoring Using Physics-Based and Data-Driven Reduced-Order Models

The needs and requirements for an electrochemical energy storage for deep space exploration is well explored. It is often understood that different mission sites and environmental conditions require different battery chemistries or technologies. Additionally, various engineering solutions are deployed to overcome specific chemical challenges. One often overlooked need is the “health” monitoring of an electrochemical storage system. The term generalized health monitoring, as envisioned in this work, refers to the monitoring of various aspects such as electrode health, electrolyte health, reaction pathway health, cooling system health, sensor health, and BMS health [1]. Generalized health monitoring allows mission leads, engineers, and scientists to incorporate flexibility in mission designs, make on-the-fly mission changes, and extend the duration of science missions. Moreover, it enables automation and data-driven decision-making without compromising safety and performance. Recently, our group developed a hierarchy of thermal reduced-order models (TROM) by combining a physics-based modeling approach and data-driven model reduction techniques applied to flight data [2]. The resulting TROMs were found to be not only accurate but also identifiable from the flight data. Consequently, the coefficient of variance of the model parameters is small over the course of hundreds of flights, allowing for monitoring the parameter evolution trajectories as the battery ages and degrades. These parameters constitute the metrics of the generalized health of a battery. Monitoring their evolution allows such models to be used for anomaly detection and prognostics, improving early detection of abnormal behavior and thus enabling timely maintenance, longer battery life, and enhanced battery safety. For this presentation, the practicality of the thermal model will be validated on a pack of 14cells under various topology configurations such as 1S14P, 2P7S, 7S2P, and 1P14S. It is well known that manufacturing and non-uniform aging lead to variability in the performance of a cell, which is exacerbated by cell balancing during active load. Additionally, in extreme scenarios, the paramount objective is to complete the mission, regardless of the stresses on the battery. Topology-induced balancing issues further stress the battery. The goal of this study is to determine if the noise (identifiability) in the reduced-order thermal model parameters is sensitive to topology, cell spacing, cooling strategy, and manufacturing or age variability. The variability in cells is considered by assuming a multimodal distribution for microscopic parameters of a cell (such as porosity, tortuosity, reaction kinetics, volumetric thermal conductivity, and volumetric heat capacity). The compounded effect of manufacturing variability, topological selection, cooling strategies, and cell balancing ages each cell in a battery differently. The study aims to clarify whether the challenge in extracting maximum information depends on the minimum number of sensors or models used for data extraction.

Automation↗

Deciphering exopolysaccharide functional specificity via visualization of chemical motifs that mediate microbial-microenvironment interactions in soil micromodels

Exopolysaccharides (EPS) are carbohydrate-based matrices of microbial biofilms that microbes use to adapt to their surroundings. Microbial EPS also promotes soil aggregate stability and contributes toward soil health by reducing erosion caused by continued land use. The chemical structure of EPS, even within single species biofilms, can vary greatly: from repeating units and branching patterns to the non-carbohydrate decorations. Despite the wealth of knowledge on EPS chemistry, many unresolved questions regarding the biological implications of EPS chemical variations remain. Here, we develop a mass spectrometry imaging toolbox that reveal how EPS chemistry enables microbial adaptation to different microenvironments such as specific moisture, soil-biofilm interfaces, and food source proximity. First, we developed emulated soil micromodels (ESMs), microfluidic channels that simulate the physical properties of soil, for biofilm formation in different microenvironments. Then, in order to map chemical features of EPS in these micromodels, we develop strategies for in-situ releasing of oligosaccharides using specific enzymes. Lastly, we optimized matrix-assisted laser desorption ionization (MALDI) mass spectrometry imaging (MSI) to spatially analyze the released compounds in ESMs.

54 ENVIRONMENTAL SCIENCES↗

Distributed heterogeneous compute infrastructure for the study of additive manufacturing systems

We present the current status of a large-scale computing framework to address the need of the multidisciplinary effort to study chemical dynamics. Specifically, we are enabling scientists to process and store experimental data, run large-scale computationally expensive high-fidelity physical simulation, and analyze these results using the state-of-the-art data analytics tools, machine learning, and uncertainty quantification methods using heterogeneous computing resources, such as CPU and GPU cluster. The framework can integrate or abstract out multiple domains based on roles. In order to develop this framework, we have leveraged an existing framework coupled with in-house heterogeneous computing resources. We present the results of using this framework on a single metadata triggered workflow to accelerate an additive manufacturing use case.

heterogeneous computing, hpc, workflows, reproduci↗