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Antimicrobial properties of nanostructured surfaces – demonstrating the need for a standard testing methodology
Bioinspired nanostructured materials that exhibit antimicrobial properties are being synthesized and tested at increasing rates for use in healthcare, manufacturing processes, and diagnostics. Although progress has been made in improving and understanding their bactericidal activity, arguably, the biggest problem currently in the field is the lack of a standard testing methodology that allows for optimal characterization and better comparison of emerging nanostructures. In this work, we examine two forms of nanostructured silicon that vary in their ability to kill certain bacterial species due to different physical mechanisms and derive guidelines for the comparative testing. We perform a comprehensive evaluation of methodologies used extensively in the field (e.g., colony counting and live dead analysis) and the novel application of high-throughput flow cytometry. The data reveal how the techniques are complementary but not always directly equivalent or correlative. Therefore, comparison of results obtained using different methodologies on different materials can be grossly misleading. We report significant variations in bactericidal efficiencies depending on experimental environments (medium type, etc.) and methodologies employed. In addition, we demonstrate how cytometry is yet another powerful complementary tool that can aid the mechanistic understanding of antimicrobial activities of rough surfaces. Besides standardization for comparison, ultimately, evaluation methods need to consider anticipated applications. Then and only then can the true potential (or limitation) of a novel material be determined for its suitability for advancement in a particular field of use.
Standard test case for a low-speed, turbulent junction vortex flow
The mean flow structure upstream, around within, and in the near wake of a turbulent junction or horseshoe vortex is reported for an incompressible subsonic flow. Measurements of the primitive variables of velocity and pressure are reported on all surfaces bounding the region of the vortex flow and on three transverse and one streamwise plane within the flowfield itself for comparisons between the measured and any calculated flow variables. Detailed surface flow visualizations and some direct force measurements of surface shear stress are also available. The data is a highly detailed, coherent, self-consistent set offered to the computational fluid mechanics community as a standard test case for the evaluation of the capability of numerical solvers intended for predicting the flowfield in such a complex, separated, three-dimensional turbulent flow. This data base is available for copying to user supplied tapes or for transmission via BITNET, as well as in two National Technical Information Service (NTIS) reports.
Dust Testing Standard Overview
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Strategies For Low-Risk Tailoring Of Thermal and Structural Reliability Test Standards
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Developing a Standard Test Program for CubeSats
Developers of CubeSats and other miniaturized satellites often lack the schedule and budget to devise and implement an extensive environmental test campaign. CubeSat projects have become increasingly common at Jet Propulsion Laboratory (JPL) over the past few years, revealing the need for a standard CubeSat test program to maximize the likelihood of mission success while meeting project cost and schedule constraints. In this paper, we describe our efforts to develop a general protoflight test program for CubeSats in low-Earth orbit (LEO) and compare this test program with a typical test program for non-CubeSat LEO satellites and instruments. We investigate the effectiveness of the CubeSat test program—both as a design and workmanship screen and as a standard needing minimal project-specific tailoring—and discuss potential areas for improvement.
Draft Standard Test Method for Characterizing Mode-I Interlaminar Fracture Toughness of Adhesives with Composite Adherends
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Strategies for Tailoring Reliability Test Standards
The paper suggests a simple strategy for the tailoring of the ground testing of unmanned spacecraft including considerations of project costs and risks. It is simply stated in five steps: (1) access the specific project's requirements and constraints, (2) use the existing comprehensive quality assurance programs as a guide, (3) prioritize the risks, (4) prioritize the tests, and (5) tailor the test program as appropriate. This approach addresses the specific project needs without unduly compromising the wealth of accumulated flight experience. Tailoring falls into three categories: tailoring of test levels, tailoring of test configurations, and tailoring of test techniques. Three examples are included to illustrate these types of tailoring activities. This paper on stratagies for tailoring spacecraft standards both advocates for and cautions against tailoring depending on the situation. Applied sensibly and carefully, tailoring can improve the test effectiveness and relax constraints on certain project resources. On the other hand, tailoring a product assurance program usually incurres some element of risk and may increase project costs.
Current Performance Characteristics of NASA Langley Research Center's Cockpit Motion Base and Standardized Test Procedure for Future Performance Characterization
This report documents the updated performance characteristics of NASA Langley Research Center's (LaRC) Cockpit Motion Base (CMB) after recent revisions that were made to its inner-loop, feedback control law. The modifications to the control law will be briefly described. The performance of the CMF will be presented. A short graphical comparison to the previous control law can be found in the appendix of this report. The revised controller will be shown to yield reduced parasitic accelerations with respect to the previous controller. Metrics based on the AGARD Advisory Report No. 144 are used to assess the overall system performance due to its recent control algorithm modification. This report also documents the standardized simulator test procedure which can be used in the future to evaluate potential updates to the control law.
Current Performance Characteristics of NASA Langley Research Center's Cockpit Motion Base and Standardized Test Procedure for Future Performance Characterization
This report documents the updated performance characteristics of NASA Langley Research Center's (LaRC) Cockpit Motion Base (CMB) after recent revisions that were made to its inner-loop, feedback control law. The modifications to the control law will be briefly described. The performance of the Cockpit Motion Facility (CMF) will be presented. A short graphical comparison to the previous control law can be found in the appendix of this report. The revised controller will be shown to yield reduced parasitic accelerations with respect to the previous controller. Metrics based on the AGARD Advisory Report No. 144 are used to assess the overall system performance due to its recent control algorithm modification. This report also documents the standardized simulator test procedure which can be used in the future to evaluate potential updates to the control law.
Proposed Ground Testing Standard Methods and Techniques
The methodologies used for prediction for on-orbit microgravity environment needs to be ground validated. The data and models for such validation will be coming from diverse sources. No standardized methodologies have been validated which cover the entire 0 - 300 Hz range. Current ground test data feeds into this process and therefore should be standardized to support both narrow and third octave band analysis.
Joint Report on Standardization Tests on N.P.L. R.A.F 15 Airfoil Model
This report contains the wind-tunnel test data obtained in the United States on a 36 by 6 inch R.A.F. 15 airfoil model prepared by the British Aeronautical Research Committee for International Trials. Tests were made in cooperation with the National Advisory Committee for Aeronautics at the Bureau of Standards, Langley Memorial Aeronautical Laboratory, Massachusetts Institute of Technology, and McCook field. In addition to brief descriptions of the various wind tunnels and methods of testing, the report contains an analysis of the test data. It is shown that while in general the agreement is quite satisfactory there are two cases in which it is unsatisfactory. Since the lack of agreement in the latter is probably explained by errors known to be inherent in the methods of determining and applying corrections in these particular tests, it is concluded that the agreement obtained is more a matter of technique than a wind tunnel characteristic. (author)
Nondestructive-test standards for evaluation of fiber-reinforced composites
Advanced composite standards, representing potential variations occurring when composites are processed into finished structures, were designed, fabricated and tested. Testing methods utilized were ultrasonic C-scan, radiography, and infrared.
Standard test evaluation of graphite fiber/resin matrix composite materials for improved toughness
Programs sponsored by NASA with the commercial transport manufacturers to develop a technology data base are required to design and build composite wing and fuselage structures. To realize the full potential of composite structures in these strength critical designs, material systems having improved ductility and interlaminar toughness are being sought. To promote systematic evaluation of new materials, NASA and the commercial transport manufacturers have selected and standardized a set of five common tests. These tests evaluate open hole tension and compression performance, compression performance after impact at an energy level of 20 ft-lb, and resistance to delamination. Ten toughened resin matrix/graphite fiber composites were evaluated using this series of tests, and their performance is compared with a widely used composite system.
JESD89 Test Standard [Slides]
This report contains a set of slides discussing JESD89A, specifically the revision of JESD89 from August 2001, intended for a presentation at a summer school at Los Alamos National Laboratory (LANL). It discusses how tests are designed and the different types of tests implemented, including real time testing, alpha testing, fast neutron testing, and thermal neutron testing.
Development of a Standard Test Method for Reducing the Uncertainties in Measuring the Capture Efficiency of Range Hoods
Cooking activities are a major source of indoor air pollutants. To control pollutants generated from cooking activities, a range hood is commonly used in residential kitchens. Several building codes require that a range hood be installed in new homes to control pollutants from cooking, and the required airflow rates for range hoods are specified by indoor air quality (IAQ) standards. However, air flow alone does not tell us how much of the cooking pollutants are exhausted by the range hood. A better metric to evaluate range hood IAQ performance is capture efficiency (CE)—the fraction of contaminants emitted during cooking that are exhausted directly to the outside via the range hood. This paper summarizes the development of a range hood CE test method for use in laboratory testing and equipment rating.
Development of a Standard Test Scenario to Evaluate the Effectiveness of Portable Fire Extinguishers on Lithium-ion Battery Fires
Many sources of fuel are present aboard current spacecraft, with one especially hazardous source of stored energy: lithium ion batteries. Lithium ion batteries are a very hazardous form of fuel due to their self-sustaining combustion once ignited, for example, by an external heat source. Batteries can become extremely energetic fire sources due to their high density electrochemical energy content that may, under duress, be violently converted to thermal energy and fire in the form of a thermal runaway. Currently, lithium ion batteries are the preferred types of batteries aboard international spacecraft and therefore are routinely installed, collectively forming a potentially devastating fire threat to a spacecraft and its crew. Currently NASA is developing a fine water mist portable fire extinguisher for future use on international spacecraft. As its development ensues, a need for the standard evaluation of various types of fire extinguishers against this potential threat is required to provide an unbiased means of comparing between fire extinguisher technologies and ranking them based on performance.
Towards the development of a standardized testing protocol for overhead island kitchen exhaust devices: Procedures, measurements and paths forward
Cooking is one of the most important sources of airborne pollutants in the indoor environments of residential buildings. Elevated concentrations of NO 2 due to cooking have been reported widely (Garret et al. 1998; Garrett et al. 1999; Mullen et al. 2016; Ryan et al. 1988; Schwab et al. 1994; J. Spengler et al. 1994; J. D. Spengler et al. 1983; Wilson et al. 1995). Many researchers have attributed elevated particulate concentrations to cooking, and some have attributed extremely high short-term concentrations of fine particles (>300 μg/m3) and ultrafine particles (>105 μg/m3) to cooking events (Abdullahi et al. 2013; Abt et al. 2000; Afshari et al. 2005; Buonanno et al. 2009; He et al. 2004; Kearney et al. 2011; Lance A. Wallace et al. 2004; See and Balasubramanian 2008; Stieb et al. 2008; Wallace and Ott 2011; Wheeler et al. 2011; Zhang et al. 2010). Cooking is also a source of other gas-phase pollutants including carbon monoxide, formaldehyde, acrolein, and other volatile organic compounds (Garret et al. 1998; Garrett et al. 1999; Logue et al. 2013; Mullen et al. 2016; Ryan et al. 1988; Schwab et al. 1994; J. Spengler et al. 1994; J. D. Spengler et al. 1983; V. Seaman et al. 2007; Wilson et al. 1995). Lastly, cooking can be a significant source of water vapor, and the water vapor produced from cooking can eventually lead to moisture-related problems (Parrott and Emmel 2003)