Effects of long-term exposure on LDEF fastener assemblies

This presentation summarizes the Systems Special Investigations Group (SIG) findings from testing and analysis of fastener assemblies used on the Long Duration Exposure Facility (LDEF) structure, the tray mounting clamps, and by the various experimenters. The LDEF deintegration team and several experimenters noted severe fastener damage and hardware removal difficulties during post-flight activities. The System SIG has investigated all reported instances, and in all cases examined to date, the difficulties were attributed to galling during installation or post-flight removal. To date, no evidence of coldwelding was found. Correct selection of materials and lubricants as well as proper mechanical procedures is essential to ensure successful on-orbit or post-flight installation and removal of hardware

Results from the testing and analysis of LDEF batteries

Batteries were used on the Long Duration Exposure Facility (LDEF) to provide power to both the active experiments and the experiment support equipment such as the Experiment Initiative System, Experiment Power and Data System (data acquisition system), and the Environment Exposure Control Canisters. Three different types of batteries were used: lithium sulfur dioxide (LiSO2), lithium carbon monofluoride (LiCF), and nickel cadmium (NiCd). A total of 92 LiSO2, 10 LiCF, and 1 NiCd batteries were flown on the LDEF. In addition, approximately 20 LiSO2 batteries were kept in cold storage at NASA LaRC. The various investigations and post-flight analyses of the flight and control batteries are reviewed. The primary objectives of these studies was to identify degradation modes (if any) of the batteries and to provide information useful to future spacecraft missions. Systems SIG involvement in the post-flight evaluation of LDEF batteries was two-fold: (1) to fund SAFT (original manufacturer of the LiSO2 batteries) to perform characterization of 13 LiSO2 batteries (10 flight and 3 control batteries); and (2) to integrate investigator results

Analysis of systems hardware flown on LDEF. Results of the systems special investigation group

The Long Duration Exposure Facility (LDEF) was retrieved after spending 69 months in low Earth orbit (LEO). LDEF carried a remarkable variety of mechanical, electrical, thermal, and optical systems, subsystems, and components. The Systems Special Investigation Group (Systems SIG) was formed to investigate the effects of the long duration exposure to LEO on systems related hardware and to coordinate and collate all systems analysis of LDEF hardware. Discussed here is the status of the LDEF Systems SIG investigation through the end of 1991

Determination of Endocannabinoid Receptor Antagonist SR141716 (Rimonabant) in Plasma by Liquid Chromatograph Tandem Mass Spectrometry

SR141716 (rimonabant) is an endocannabinoid receptor antagonist. Endocannabinoids are a class of chemicals that affect neurotransmission via G-protein coupled CB1 (brain) and CB2 (peripheral tissue) receptors. Numerous animal studies have shown that SR141716 binds with the CB1 receptor in the brain, resulting in several biological consequences including reduced alcohol intake and reward as well as reduced food consumption. In this work, an analytical method based on liquid chromatography and electrospray ionization tandem mass spectrometry (LC–ESI-MS/MS) has been developed and validated for the quantitative measurement of SR141716 in both human and rat plasma to support the investigation of this compound. A suitable internal standard (AM251) has been chosen and the experimental conditions have been optimized for the separation and detection of singly charged positive ions of SR141716 and the internal standard. A protein precipitation protocol has been developed for extraction of SR141716 and the internal standard from plasma samples. Quantitation was achieved using multiple-reaction-monitoring (MRM) mode for SR141716 (m/z 463 → m/z 363) and the internal standard (m/z 555 → m/z 455) and calibration curve over the concentration range of 5.00–1000 ng/ml was plotted using the peak-area ratio versus the concentration of SR141716 with a LOD and LLOQ of 1.09 and 3.62 ng/ml, respectively. The method developed has been used to analyze SR141716 in rat plasma samples from an animal study

Influence of Longitudinal Position on the Evolution of Steady-State Signal in Cardiac Cine Balanced Steady-State Free Precession Imaging

Background: Emerging quantitative cardiac magnetic resonance imaging (CMRI) techniques use cine balanced steady-state free precession (bSSFP) to measure myocardial signal intensity and probe underlying physiological parameters. This correlation assumes that steady-state is maintained uniformly throughout the heart in space and time. Purpose: To determine the effects of longitudinal cardiac motion and initial slice position on signal deviation in cine bSSFP imaging by comparing two-dimensional (2D) and three-dimensional (3D) acquisitions. Material and Methods: Nine healthy volunteers completed cardiac MRI on a 1.5-T scanner. Short axis images were taken at six slice locations using both 2D and 3D cine bSSFP. 3D acquisitions spanned two slices above and below selected slice locations. Changes in myocardial signal intensity were measured across the cardiac cycle and compared to longitudinal shortening. Results: For 2D cine bSSFP, 46% ± 9% of all frames and 84% ± 13% of end-diastolic frames remained within 10% of initial signal intensity. For 3D cine bSSFP the proportions increased to 87% ± 8% and 97% ± 5%. There was no correlation between longitudinal shortening and peak changes in myocardial signal. The initial slice position significantly impacted peak changes in signal intensity for 2D sequences (P \u3c 0.001). Conclusion: The initial longitudinal slice location significantly impacts the magnitude of deviation from steady-state in 2D cine bSSFP that is only restored at the center of a 3D excitation volume. During diastole, a transient steady-state is established similar to that achieved with 3D cine bSSFP regardless of slice location

Quantitative Gadolinium-Free Cardiac Fibrosis Imaging in End Stage Renal Disease Patients Reveals a Longitudinal Correlation with Structural and Functional Decline

Patients with end stage renal disease (ESRD) suffer high mortality from arrhythmias linked to fibrosis, but are contraindicated to late gadolinium enhancement magnetic resonance imaging (MRI). We present a quantitative method for gadolinium-free cardiac fibrosis imaging using magnetization transfer (MT) weighted MRI, and probe correlations with widely used surrogate markers including cardiac structure and contractile function in patients with ESRD. In a sub-group of patients who returned for follow-up imaging after one year, we examine the correlation between changes in fibrosis and ventricular structure/function. Quantification of changes in MT revealed significantly greater fibrotic burden in patients with ESRD compared to a healthy age matched control cohort. Ventricular mechanics, including circumferential strain and diastolic strain rate were unchanged in patients with ESRD. No correlation was observed between fibrotic burden and concomitant measures of either circumferential or longitudinal strains or strain rates. However, among patients who returned for follow up examination a strong correlation existed between initial fibrotic burden and subsequent loss of contractile function. Gadolinium-free myocardial fibrosis imaging in patients with ESRD revealed a complex and longitudinal, not contemporary, association between fibrosis and ventricular contractile function

The Vehicle, Fall 1994

Table of Contents Poetry Noah\u27s WifeJennifer Moropage 8-9 The Intensity of a BreathHeather Anne Winterspage 10-11 When I Was RainNicole Moonpage 11 Wreckage at Low Tide, After a Storm On Cape FearMatt Parkspage 12-14 two belowKeith Spearpage 16 HeatScott Langrenpage 17 Plastic Shard WordsMatthew J. Nelsonpage 18 Mr. Snowplow ManMartin Paul Brittpage 19 Carpe DiemMichael Lairpage 19 untitledWalt Howardpage 20 The GameKellie J. Olsenpage 21 AT PEACEJennifer Surmanpage 22 SawdustSue Songerpage 23 Photography Unbound RealitiesKris Quiriconipage 26 untitled Mark Porter page 27 untitled Mark Porter page 28 untitled Mark Porter page 29 Prose I am Here...RememberingJ. Dylan McNeillpage 32-34 RecognitionSue Songerpage 35-36 SACCADICSteve Beinpage 37-40 The BurnBryan Levekpage 41-45 Biographiespage 46-48https://thekeep.eiu.edu/vehicle/1063/thumbnail.jp

The Vehicle, Fall 1994

Table of Contents Poetry Noah\u27s WifeJennifer Moropage 8-9 The Intensity of a BreathHeather Anne Winterspage 10-11 When I Was RainNicole Moonpage 11 Wreckage at Low Tide, After a Storm On Cape FearMatt Parkspage 12-14 two belowKeith Spearpage 16 HeatScott Langrenpage 17 Plastic Shard WordsMatthew J. Nelsonpage 18 Mr. Snowplow ManMartin Paul Brittpage 19 Carpe DiemMichael Lairpage 19 untitledWalt Howardpage 20 The GameKellie J. Olsenpage 21 AT PEACEJennifer Surmanpage 22 SawdustSue Songerpage 23 Photography Unbound RealitiesKris Quiriconipage 26 untitled Mark Porter page 27 untitled Mark Porter page 28 untitled Mark Porter page 29 Prose I am Here...RememberingJ. Dylan McNeillpage 32-34 RecognitionSue Songerpage 35-36 SACCADICSteve Beinpage 37-40 The BurnBryan Levekpage 41-45 Biographiespage 46-48https://thekeep.eiu.edu/vehicle/1063/thumbnail.jp

The N2K Consortium. I. A Hot Saturn Planet Orbiting HD 88133

The N2K ("next 2000") consortium is carrying out a distributed observing campaign with the Keck, Magellan, and Subaru telescopes, as well as the automatic photometric telescopes of Fairborn Observatory, in order to search for short-period gas giant planets around metal-rich stars. We have established a reservoir of more than 14,000 main-sequence and subgiant stars closer than 110 pc, brighter than V = 10.5, and with 0.4 0.1 dex for this survey. We outline the strategy and report the detection of a planet orbiting the metal-rich G5 IV star HD 88133 with a period of 3.41 days, semivelocity amplitude K = 35.7 m s^(-1), and M sin i = 0.29M_J. Photometric observations reveal that HD 88133 is constant on the 3.415 day radial velocity period to a limit of 0.0005 mag. Despite a transit probability of 19.5%, our photometry rules out the shallow transits predicted by the large stellar radius