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DOE OSTI2020

Internal Fragments Generated by Electron Ionization Dissociation Enhance Protein Top-Down Mass Spectrometry

Top-down proteomics by mass spectrometry (MS) involves the mass measurement of an intact protein followed by subsequent activation of the protein to generate product ions. Electron-based fragmentation methods like electron capture dissociation and electron transfer dissociation are widely used for these types of analyses. Recently, electron ionization dissociation (EID), which utilizes higher energy electrons (>20 eV) has been suggested to be more efficient for top-down protein fragmentation compared to other electron-based dissociation methods. In this paper, we demonstrate that the use of EID enhances protein fragmentation and subsequent detection of protein fragments. Protein product ions can form by either single cleavage events, resulting in terminal fragments containing the C-terminus or N-terminus of the protein, or by multiple cleavage events to give rise to internal fragments that include neither the C-terminus nor the N-terminus of the protein. Conventionally, internal fragments have been disregarded, as reliable assignments of these fragments were limited. Here, we demonstrate that internal fragments generated by EID can account for ~20–40% of the mass spectral signals detected by top-down EID-MS experiments. By including internal fragments, the extent of the protein sequence that can be explained from a single tandem mass spectrum increases from ~50 to ~99% for 29 kDa carbonic anhydrase II and 8.6 kDa ubiquitin. When searching for internal fragments during data analysis, previously unassigned peaks can be readily and accurately assigned to confirm a given protein sequence and to enhance the utility of top-down protein sequencing experiments.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2023

Low temperature absolute internal quantum efficiency of InGaN-based light-emitting diodes

A method to reveal low temperature absolute internal quantum efficiency of an InGaN-based light-emitting diode (LED) is reported. Structural (via scanning electron and atomic force microscopies, x-ray diffraction, and Raman spectroscopy) and optical (via temperature- and power-dependent photoluminescence) properties of InGaN-based blue LEDs are coupled with a channel-based recombination model, which reveals the low temperature absolute internal quantum efficiency of the LED on traditional sapphire and emerging Si (111) substrates as 27.5% and 71.1%, respectively. High low-temperature absolute internal quantum efficiency of the former is attributed to its lower defect density and less strain. Furthermore, our results show assuming perfect (i.e., 100%) internal quantum efficiency in an InGaN-based LED at low temperatures could be misleading, and using negative thermal quenching properties of defect luminesce bands with a channel-based recombination model can be a method to quantify LED's less than ideal low temperature internal quantum efficiencies.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Long plasma duration operation analyses with an international multi-machine (tokamaks and stellarators) database

Combined high-fusion performance and long-pulse operation is one of the key integration challenges for fusion energy development in magnetic devices. Addressing these challenges requires an integrated vision of physics and engineering aspects with the purpose of simultaneously increasing time duration and fusion performance. Significant progress has been made in tokamaks and stellarators, including very recent achievement in duration and/or performance. This progress is reviewed by analyzing the experimental data (109 plasma pulses with a total of 3200 data points, i.e. on average 29 data per pulse) provided by ten tokamaks (in alphabetical order: Axially Symmetric Divertor Experiment Upgrade, DIII-D, Experimental Advanced Superconducting Tokamak, Joint European Torus, JT-60 Upgrade, Korea Superconducting Tokamak Advanced Research, tokamak à configuration variable, Tokamak Fusion Test Reactor, Tore Supra, W Environment in Steady-State Tokamak) and two stellarators (Large Helical Device and Wendelstein 7-X) expanding the pioneering work of Kikuchi (Kikuchi M. and Azumi M. 2015 Frontiers in Fusion Research II: Introduction to Modern Tokamak Physics (Springer)). Data have been gathered up to January 2022 and coordination has been provided by the recently created International Energy Agency-International Atomic Energy Agency international Coordination on International Challenges on Long duration OPeration group. By exploiting the multi-machine international database, recent progress in terms of injected energies (e.g. 1730 MJ in L-mode, 425 MJ in H-mode), durations (1056 s in L-mode, 101 s in H-mode), injected powers, and sustained performance will be reviewed. Progress has been made to sustain long-pulse operation in tokamaks and stellarators with superconducting coils, actively cooled components, and/or with metallic walls. The graph of the fusion triple products as a function of duration shows a dramatic reduction of, at least two orders of magnitude when increasing the plasma duration from less than 1 s to 100 s. Indeed, long-pulse operation is usually reached in dominant electron-heating modes at reduced density (current drive optimization) but with low ion temperatures ranging from 1 to 3 keV for discharges above 100 s. Difficulties in extending the duration may arise from coupling high heating powers over long durations and the evolving plasma-wall interaction towards an unstable operational domain. Possible causes limiting the duration and critical issues to be addressed prior to ITER operation and DEMO design are reported and analyzed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2023

Intrinsic value of the international benchmark projects, ICSBEP and IRPhEP, for advanced reactor development

The International Criticality Safety Benchmark Evaluation Project, a sanctioned program under the auspices of the Nuclear Energy Agency of the Organisation for Economic Co-operation and Development, has been a highly successful and productive collaboration, now encompassing over 5,000 evaluated experimental benchmarks trusted and relied upon throughout the international nuclear communities. The success of this project led to the development of the International Reactor Physics Experiment Evaluation Project, which is dedicated to the evaluation of benchmark experiment data to sustain current and future reactor physics validation needs. These exemplary programs, and their widely utilized handbooks, serve as gold standards to which other databases strive to emulate. The purpose of the two projects is to preserve modern and legacy experimental data and evaluate it in a standardized handbook format to provide quality benchmarks to support modern and future criticality safety and reactor physics validation. These two projects have often served as the mechanism through which historic and modern neutronics experiments are evaluated and shared across international borders, to best provide unique, high-quality peer-reviewed, and often otherwise unavailable, benchmark data. The contents of these handbooks are utilized not only in validating criticality safety, reactor physics, and advanced reactor calculations, but are used to validate neutronics calculations and nuclear data for most other nuclear applications. This paper discusses both international programs and available content to enable advanced reactor design validation.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2021

Measurement of internal dark current in a 17 GHz accelerator structure with an elliptical sidewall

A 17 GHz single cell, standing wave, copper accelerator structure with an axisymmetric elliptical central cell sidewall was tested for internal and downstream dark current as a function of gradient up to 93 MV/m. The elliptical sidewall was predicted to suppress the internal dark current and the lower order multipactor modes as compared with a previously tested structure having a straight sidewall. During the conditioning phase of the elliptical sidewall structure, strong internal dark current generated by an N = 1 multipactor mode was observed at gradients in the 10 to 20 MV/m range. After conditioning with 2.2x10^5 pulses to 93 MV/m, the N = 1 mode was completely suppressed and no multipactor resonances were observed. The internal dark current was reduced to a comparatively low level, much smaller than in the previously studied, straight sidewall structure, in good agreement with simulations. The energy spectrum of the electrons colliding with the sidewall was measured using an isolated side dark current monitor and a bias voltage. As the conditioning progressed, the electron energy spectrum showed an increase in the concentration of lower energy electrons, also in good agreement with simulations. Studies of internal dark current may help to understand the rf conditioning and ultimate performance of high gradient accelerator structures.

43 PARTICLE ACCELERATORS↗

NASA NTRS1970

Thermodynamics of the internal combustion engine

The ubiquitous automobile has played both the role of hero and villain during the course of its history. At the present time it is being cast as the villain with increasing frequency because it has been indicted as a major source of air pollution. It is just this characterization that is responsible for our renewed interest in the automobile. When we speak of the automobile as a source of air pollution, we really mean the heart of the automobile, the internal combustion engine. The prototype of the modern internal combustion engine was first successfully operated by Nicholas August Otto in 1876. In spite of its long history, the internal combustion engine is still poorly understood in terms of the details of the physical processes that take place during its operations. The internal combustion engine operates on what is known as the Otto cycle, and Otto cycle calculations have been with us for many years. The emphasis in earlier calculations was usually on the performance rather than on the pollution aspects. Performance characteristics can often be estimated reasonably accurately even with a considerable degree of simplification. We are interested in the pollution aspects of the internal combustion engine, and therefore the calculations must be performed with more care. Our extensive experience with equilibrium calculations places us in a position to carry out such careful calculations. We have just recently begun such an analysis, and its objective is the prediction of exhaust gas properties. I will describe our progress by first reviewing the Otto cycle, and then I will illustrate the effect of various assumptions on the calculated results.

Frank J. Zeleznik↗

NASA NTRS1950

Improvements in Heat Transfer for Anti-Icing of Gas-Heated Airfoils with Internal Fins and Partitions

The effect of modifying the gas passage of hollow metal airfoils by the additIon of internal fins and partitions was experimentally investigated and comparisons were made among a basic unfinned airfoil section and two airfoil designs having metal fins attached at the leading edge of the internal gas passage. An analysis considering the effects of heat conduction in the airfoil metal was made to determine the internal modification effectiveness that may be obtained in gas-heated components, such as turbojet-inlet guide vanes, support struts, hollow propeller blades, arid. thin wings. Over a wide range of heated-gas flow and tunnel-air velocity, the increase In surface-heating rates with internal finning was marked (up to 3.5 times), with the greatest increase occurring at the leading edge where anti-icing heat requirements are most critical. Variations in the amount and the location of internal finning and. partitioning provided. control over the local rates of surface heat transfer and permitted efficient anti-icing utilization of the gas-stream heat content.

Gray, Vernon H.↗

NASA NTRS1984

Internal waves in the Gulf of California - Observations from a spaceborne radar

Pronounced signatures of internal waves were detected repeatedly in the Gulf of California by the Seasat synthetic aperture radar (SAR). A series of nine images with exactly repeating ground coverage was used to study the temporal variability of the internal wave field in the area. It was found that the number of observed wave groups was highly correlated with the strength of the local tides: the maximum number occurred during spring tides and the minimum number occurred during neap tides, indicating that the internal waves were tidally forced. Most of the wave activity was found to the north of 28 deg N where the tides were the strongest in the Gulf. The application of a simple, nonlinear internal wave model to the observations indicated that the peak-to-peak amplitude of the observed waves was about 50 m with an uncertainty of a factor of 2. The estimated upper bound for the rate of the loss of tidal energy to internal waves was about 5 x 10 to the 15th erg/s, representing only 10 percent of the rate of the dissipation of the dominant M2 tide in the Gulf.

Fu, L.-L.↗

NASA NTRS1984

SAR internal wave signature experiment

Internal wave and surface wave observations by research vessels will be conducted in conjunction with aircraft SAR images. Synthetic Aperture Radar Internal Wave Signature Experiment (SARSEX) provides an opportunity to acquire aircraft and spacecraft SAR imagery of internal waves with appropriate sea truth data. Objectives are to investigate basic mechanisms (both hydrodynamic and electromagnetic) responsible for internal wave signatures and quantitatively test theories and models for predicting internal wave signatures from given ocean and radar parameters.

Winokur, R. S.↗

NASA NTRS1990

International cooperation for Mars exploration and sample return

The National Research Council's Space Studies Board has previously recommended that the next major phase of Mars exploration for the United States involve detailed in situ investigations of the surface of Mars and the return to earth for laboratory analysis of selected Martian surface samples. More recently, the European space science community has expressed general interest in the concept of cooperative Mars exploration and sample return. The USSR has now announced plans for a program of Mars exploration incorporating international cooperation. If the opportunity becomes available to participate in Mars exploration, interest is likely to emerge on the part of a number of other countries, such as Japan and Canada. The Space Studies Board's Committee on Cooperative Mars Exploration and Sample Return was asked by the National Aeronautics and Space Administration (NASA) to examine and report on the question of how Mars sample return missions might best be structured for effective implementation by NASA along with international partners. The committee examined alternatives ranging from scientific missions in which the United States would take a substantial lead, with international participation playing only an ancillary role, to missions in which international cooperation would be a basic part of the approach, with the international partners taking on comparably large mission responsibilities. On the basis of scientific strategies developed earlier by the Space Studies Board, the committee considered the scientific and technical basis of such collaboration and the most mutually beneficial arrangements for constructing successful cooperative missions, particularly with the USSR.

Levy, Eugene H.↗

NASA NTRS1990

Methods for determining the internal thrust of scramjet engine modules from experimental data

Methods for calculating zero-fuel internal drag of scramjet engine modules from experimental measurements are presented. These methods include two control-volume approaches, and a pressure and skin-friction integration. The three calculation techniques are applied to experimental data taken during tests of a version of the NASA parametric scramjet. The methods agree to within seven percent of the mean value of zero-fuel internal drag even though several simplifying assumptions are made in the analysis. The mean zero-fuel internal drag coefficient for this particular engine is calculated to be 0.150. The zero-fuel internal drag coefficient when combined with the change in engine axial force with and without fuel defines the internal thrust of an engine.

Voland, Randall T.↗

NASA NTRS1990

Differences in the size-internal velocity relation of galactic and extragalactic HII regions

The nature of the size-internal velocity relation in extragalactic HII regions is examined in order to improve their use as distance determinants. The relation between the linear size and the internal velocity was compared for HII regions in the Galaxy and in external galaxies. Data for the former are from the researcher's own studies at high spatial resolution, while the latter have been the subject of spectroscopy that includes almost the entire objects. The Galactic HII regions are corrected to values of the internal velocity that would be observed if they were at extragalactic distances. A very different size-internal velocity relation was found for the two types of objects in the sense that the extragalactic objects are some ten times larger at the same internal velocity. This is interpreted to mean that the extragalactic HII regions are actually complexes of small HII regions comparable in size to their Galactic counterparts.

Odell, C. R.↗

NASA NTRS1991

The 1991 International Conference on Aging Aircraft and Structural Airworthiness

Civil aviation serves a strategic interest to the United States. Thus, the need to maintain a high standard of aviation safety is axiomatic. While the industry has witnessed phenomenal growth in the past two decades, the proportion of aging aircraft in air carrier fleets has been ever increasing-a trend that is projected to continue. Certain events which occurred in 1988 and previous years and public concern about the safety of the high time aircraft led to an International Conference on Aging Aircraft in Washington, D.C., during which a number of aviation safety related issues applicable to aging aircraft were raised and discussed among the conference participants. Various groups that have a vital stake in commercial aviation made certain recommendations which led to the formation of a task force and a broad undertaking involving the Federal Aviation Administration (FAA), the National Aeronautics and Space Administration (NASA), industry and international organizations to insure continued airworthiness of aging airplanes. At the same time, significant research and development programs were initiated by the FAA and NASA to complement the broader effort. In view of the success of the 1988 conference, the FAA desired that conferences be held annually to disseminate information on the status of the task force's activities on aircraft certification and airline maintenance related issues and to offer a forum for participation by all interested parties. Thus, the 2nd International Conference was held in 1989 in Baltimore and the third in the series in 1990 in Bordeaux, France. Both of them, like the first conference, attracted rousing attendance and interest. Thus, the stage was set for organizing the 4th International Conference in 1991. By 1991, the FAA and NASA research programs were yielding significant results, a consideration that led to a larger segment of the 4th International Conference Program being devoted to presentations about the impact of the research on the other activities of the task group. Agreement had also been reached between the FAA and NASA to coordinate and integrate their respective program activities. Hence, NASA was co-opted as a sponsor of the conference. A group consisting of Mr. Stephen Erickson of the Air Transport Association of America, Mr. Jesse Lewis and Mr. Richard Johnson of the FAA, and Mr. Thomas Crooker of NASA was formed to organize the conference. The members of the group are owed special thanks for their efforts that ensured the success of the conference.

Aging Aircraft↗

NASA NTRS2001

Thermo-Elastic Analysis of Internally Cooled Structures Using a Higher Order Theory

This paper presents the results of a study on the thermomechanical behavior of internally cooled silicon nitride structures. Silicon nitride is under consideration for elevated temperature aerospace engine applications. and techniques for lowering the operating temperature of structures composed of this material are under development. Lowering the operating temperature provides a large payoff in terms of fatigue life and may be accomplished through the use of thermal barrier coatings (TBC's) and the novel concept of included cooling channels. Herein, an in-depth study is performed on the behavior of a flame-impinged silicon nitride plate with a TBC and internal channels cooled by forced air. The analysis is performed using the higher order theory for functionally graded materials (HOTFGM), which has been developed through NASA Glenn Research Center funding over the past several years. HOTFGM was chosen over the traditional finite element approach as a prelude to an examination of functionally graded silicon nitride structures for which HOTFGM is ideally suited. To accommodate the analysis requirement% of the internally cooled plate problem, two crucial enhancements were made to the two-dimensional Cartesian-based version of HOTFGM. namely, incorporation of internal boundary capabilities and incorporation of convective boundary conditions. Results indicate the viability and large benefits of cooling the plate via forced air through cooling channels. Furthermore, cooling can positively impact the stress and displacement fields present in the plate, yielding an additional payoff in terms of fatigue life. Finally, a spin-off capability resulted from inclusion of internal boundaries within HOTFGM; the ability to simulate the thermo-elastic response of structures with curved surfaces. This new capability is demonstrated, and through comparison with an analytical solution, shown to be viable and accurate.

Arnold, Steven M.↗

NASA NTRS2000

International Laser Ranging Service (ILRS): Terms of Reference

The International Laser Ranging Service (ILRS) is an established Service within Section II , Advanced Space Technology, of the International Association of Geodesy (IAG). The primary objective of the ILRS is to provide a service to support, through Satellite and Lunar Laser Ranging data and related products, geodetic and geophysical research activities as well as International Earth Rotation Service (IERS) products important to the maintenance of an accurate International Terrestrial Reference Frame (ITRF). The service also develops the necessary standards/specifications and encourages international adherence to its conventions.

Husson, Van↗

NASA NTRS2003

Amateur Radio on the International Space Station - Phase 2 Hardware System

The International Space Station (ISS) ham radio system has been on-orbit for over 3 years. Since its first use in November 2000, the first seven expedition crews and three Soyuz taxi crews have utilized the amateur radio station in the Functional Cargo Block (also referred to as the FGB or Zarya module) to talk to thousands of students in schools, to their families on Earth, and to amateur radio operators around the world. Early on, the Amateur Radio on the International Space Station (ARISS) international team devised a multi-phased hardware development approach for the ISS ham radio station. Three internal development Phases. Initial Phase 1, Mobile Radio Phase 2 and Permanently Mounted Phase 3 plus an externally mounted system, were proposed and agreed to by the ARISS team. The Phase 1 system hardware development which was started in 1996 has since been delivered to ISS. It is currently operational on 2 meters. The 70 cm system is expected to be installed and operated later this year. Since 2001, the ARISS international team have worked to bring the second generation ham system, called Phase 2, to flight qualification status. At this time, major portions of the Phase 2 hardware system have been delivered to ISS and will soon be installed and checked out. This paper intends to provide an overview of the Phase 1 system for background and then describe the capabilities of the Phase 2 radio system. It will also describe the current plans to finalize the Phase 1 and Phase 2 testing in Russia and outlines the plans to bring the Phase 2 hardware system to full operation.

Bauer, F.↗

NASA NTRS2004

The Living With a Star Program and International Collaboration

International cooperation has long been a vital element in the scientific investigation of solar variability and its impact on Earth and the space environment. Recently a new international cooperative initiative in solar-terrestrial physics has been established by the major space agencies of the world, called the International Living With a Star (ILWS) program. ILWS is a follow-on to the highly successful International Solar Terrestrial Physics (ISTP) program, which derived its success from the ,cooperation of a number of international partners. ISTP, with its steady flow of discoveries and new knowledge in solar-terrestrial physics, has laid the foundation for the coordinated study of the Sun-Earth system as a connected stellar-planetary system and as humanity's home. The first step in establishing ILWS was taken in the fall of 2000 when funding was approved for the NASA's LWS program whose goal is to "develop the scientific understanding necessary to effectively address those aspects of the connected Sun-Earth system that directly affect life and society".

Thompson, Barbara J.↗

NASA NTRS2004

The International Space Station: A Pathway to the Future

Nearly six years after the launch of the first International Space Station element, and four years after its initial occupation, the United States and our 16 international partners have made great strides in operating this impressive Earth orbiting research facility. This past year we have done so in the face of the adversity of operating without the benefit of the Space Shuttle. In his January 14, 2004, speech announcing a new vision for America's space program, President Bush affirmed the United States' commitment to completing construction of the International Space Station by 2010. The President also stated that we would focus our future research aboard the Station on the longterm effects of space travel on human biology. This research will help enable human crews to venture through the vast voids of space for months at a time. In addition, ISS affords a unique opportunity to serve as an engineering test bed for hardware and operations critical to the exploration tasks. NASA looks forward to working with our partners on International Space Station research that will help open up new pathways for future exploration and discovery beyond low Earth orbit. This paper provides an overview of the International Space Station Program focusing on a review of the events of the past year, as well as plans for next year and the future.

Kitmacher, Gary H.↗