Oxidation and protection of fiberglass-epoxy composite masts for photovoltaic arrays in the low Earth orbital environment

Fiberglass-epoxy composites are considered for use as structural members for the mast of the space station solar array panel. The low Earth orbital environment in which space station is to operate is composed mainly of atomic oxygen, which has been shown to cause erosion of many organic materials and some metals. Ground based testing in a plasma asher was performed to determine the extent of degradation of fiberglass-epoxy composites when exposed to a simulated atomic oxygen environment. During exposure, the epoxy at the surface of the composite was oxidized, exposing individual glass fibers which could easily be removed. Several methods of protecting the composite were evaluated in an atomic oxygen environment and with thermal cycling and flexing. The protection techniques evaluated to date include an aluminum braid covering, an indium-tin eutectic and a silicone based paint. The open aluminum braid offered little protection while the CV-1144 coating offered some initial protection against atomic oxygen, but appears to develop cracks which accelerate degradation when flexed. Coatings such as the In-Sn eutectic may provide adequate protection by containing the glass fibers even though mass loss still occurs

Spaceflight Safety on the North Coast of America

Spaceflight Safety (SFS) engineers at NASA Lewis Research Center (LeRC) are responsible for evaluating the microgravity fluids and combustion experiments, payloads and facilities developed at NASA LeRC which are manifested for spaceflight on the Space Shuttle, the Russian space station Mir, and/or the International Space Station (ISS). An ongoing activity at NASA LeRC is the comprehensive training of its SFS engineers through the creation and use of safety tools and processes. Teams of SFS engineers worked on the development of an Internet website (containing a spaceflight safety knowledge database and electronic templates of safety products) and the establishment of a technical peer review process (known as the Safety Assurance for Lewis Spaceflight Activities (SALSA) review)

Radiomics for the detection of diffusely impaired myocardial perfusion: A proof-of-concept study using 13N-ammonia positron emission tomography

AIM The current proof-of-concept study investigates the value of radiomic features from normal 13N-ammonia positron emission tomography (PET) myocardial retention images to identify patients with reduced global myocardial flow reserve (MFR). METHODS Data from 100 patients with normal retention 13N-ammonia PET scans were divided into two groups, according to global MFR (i.e., < 2 and ≥ 2), as derived from quantitative PET analysis. We extracted radiomic features from retention images at each of five different gray-level (GL) discretization (8, 16, 32, 64, and 128 bins). Outcome independent and dependent feature selection and subsequent univariate and multivariate analyses was performed to identify image features predicting reduced global MFR. RESULTS A total of 475 radiomic features were extracted per patient. Outcome independent and dependent feature selection resulted in a remainder of 35 features. Discretization at 16 bins (GL16) yielded the highest number of significant predictors of reduced MFR and was chosen for the final analysis. GLRLM_GLNU was the most robust parameter and at a cut-off of 948 yielded an accuracy, sensitivity, specificity, negative and positive predictive value of 67%, 74%, 58%, 64%, and 69%, respectively, to detect diffusely impaired myocardial perfusion. CONCLUSION A single radiomic feature (GLRLM_GLNU) extracted from visually normal 13N-ammonia PET retention images independently predicts reduced global MFR with moderate accuracy. This concept could potentially be applied to other myocardial perfusion imaging modalities based purely on relative distribution patterns to allow for better detection of diffuse disease

GABAergic circuits reflect different requirements for emergent perception in postnatal mouse neocortex

Information transfer in the mammalian cerebral cortex is dependent on locally-projecting GABAergic interneuron circuits that are widely assumed to be uniform across neocortical areas. We demonstrate that this does not hold true during the highly dynamic period of postnatal life prior to the onset of active sensory exploration. During this time, a subset of interneuron defined by expression of the neuropeptide somatostatin differentially contribute to sensory-evoked activity in primary somatosensory and visual cortices. This functional divergence between the two areas is explained by differences in the composition of somatostatin interneuron subtypes and the transient circuits formed by these cells; the somatosensory circuit representing an adaptation to control early neonatal touch information. Understanding such area-dependent differences will promote our endeavours to understand the aetiology of developmental psychiatric disorders

Post-hoc motion correction for coronary computed tomography angiography without additional radiation dose - Improved image quality and interpretability for “free”

Objective To evaluate the impact of a motion-correction (MC) algorithm, applicable post-hoc and not dependent on extended padding, on the image quality and interpretability of coronary computed tomography angiography (CCTA). Methods Ninety consecutive patients undergoing CCTA on a latest-generation 256-slice CT device were prospectively included. CCTA was performed with prospective electrocardiogram-triggering and the shortest possible acquisition window (without padding) at 75% of the R-R-interval. All datasets were reconstructed without and with MC of the coronaries. The latter exploits the minimal padding inherent in cardiac CT scans with this device due to data acquisition also during the short time interval needed for the tube to reach target currents and voltage (“free” multiphase). Two blinded readers independently assessed image quality on a 4-point Likert scale for all segments. Results A total of 1,030 coronary segments were evaluated. Application of MC both with automatic and manual coronary centerline tracking resulted in a significant improvement in image quality as compared to the standard reconstruction without MC (mean Likert score 3.67 [3.50;3.81] vs 3.58 [3.40;3.73], P = 0.005, and 3.7 [3.55;3.82] vs 3.58 [3.40;3.73], P < 0.001, respectively). Furthermore, MC significantly reduced the proportion of non-evaluable segments and patients with at least one non-evaluable coronary segment from 2% to as low as 0.3%, and from 14% to as low as 3%. Reduction of motion artifacts was predominantly observed in the right coronary artery. Conclusions A post-hoc device-specific MC algorithm improves image quality and interpretability of prospectively electrocardiogram-triggered CCTA and reduces the proportion of non-evaluable scans without any additional radiation dose exposure

Long-term impact of myocardial inflammation on quantitative myocardial perfusion-a descriptive PET/MR myocarditis study.

PURPOSE Whether myocardial inflammation causes long-term sequelae potentially affecting myocardial blood flow (MBF) is unknown. We aimed to assess the effect of myocardial inflammation on quantitative MBF parameters, as assessed by 13N-ammonia positron emission tomography myocardial perfusion imaging (PET-MPI) late after myocarditis. METHODS Fifty patients with a history of myocarditis underwent cardiac magnetic resonance (CMR) imaging at diagnosis and PET/MR imaging at follow-up at least 6 months later. Segmental MBF, myocardial flow reserve (MFR), and 13N-ammonia washout were obtained from PET, and segments with reduced 13N-ammonia retention, resembling scar, were recorded. Based on CMR, segments were classified as remote (n = 469), healed (inflammation at baseline but no late gadolinium enhancement [LGE] at follow-up, n = 118), and scarred (LGE at follow-up, n = 72). Additionally, apparently healed segments but with scar at PET were classified as PET discordant (n = 18). RESULTS Compared to remote segments, healed segments showed higher stress MBF (2.71 mL*min-1*g-1 [IQR 2.18-3.08] vs. 2.20 mL*min-1*g-1 [1.75-2.68], p < 0.0001), MFR (3.78 [2.83-4.79] vs. 3.36 [2.60-4.03], p < 0.0001), and washout (rest 0.24/min [0.18-0.31] and stress 0.53/min [0.40-0.67] vs. 0.22/min [0.16-0.27] and 0.46/min [0.32-0.63], p = 0.010 and p = 0.021, respectively). While PET discordant segments did not differ from healed segments regarding MBF and MFR, washout was higher by ~ 30% (p < 0.014). Finally, 10 (20%) patients were diagnosed by PET-MPI as presenting with a myocardial scar but without a corresponding LGE. CONCLUSION In patients with a history of myocarditis, quantitative measurements of myocardial perfusion as obtained from PET-MPI remain altered in areas initially affected by inflammation. CMR = cardiac magnetic resonance; PET = positron emission tomography; LGE = late gadolinium enhancement

Long-term impact of myocardial inflammation on quantitative myocardial perfusion-a descriptive PET/MR myocarditis study

PURPOSE Whether myocardial inflammation causes long-term sequelae potentially affecting myocardial blood flow (MBF) is unknown. We aimed to assess the effect of myocardial inflammation on quantitative MBF parameters, as assessed by 13N-ammonia positron emission tomography myocardial perfusion imaging (PET-MPI) late after myocarditis. METHODS Fifty patients with a history of myocarditis underwent cardiac magnetic resonance (CMR) imaging at diagnosis and PET/MR imaging at follow-up at least 6 months later. Segmental MBF, myocardial flow reserve (MFR), and 13N-ammonia washout were obtained from PET, and segments with reduced 13N-ammonia retention, resembling scar, were recorded. Based on CMR, segments were classified as remote (n = 469), healed (inflammation at baseline but no late gadolinium enhancement [LGE] at follow-up, n = 118), and scarred (LGE at follow-up, n = 72). Additionally, apparently healed segments but with scar at PET were classified as PET discordant (n = 18). RESULTS Compared to remote segments, healed segments showed higher stress MBF (2.71 mL*min$^{-1}$*g$^{-1}$ [IQR 2.18-3.08] vs. 2.20 mL*min$^{-1}$*g$^{-1}$ [1.75-2.68], p < 0.0001), MFR (3.78 [2.83-4.79] vs. 3.36 [2.60-4.03], p < 0.0001), and washout (rest 0.24/min [0.18-0.31] and stress 0.53/min [0.40-0.67] vs. 0.22/min [0.16-0.27] and 0.46/min [0.32-0.63], p = 0.010 and p = 0.021, respectively). While PET discordant segments did not differ from healed segments regarding MBF and MFR, washout was higher by ~ 30% (p < 0.014). Finally, 10 (20%) patients were diagnosed by PET-MPI as presenting with a myocardial scar but without a corresponding LGE. CONCLUSION In patients with a history of myocarditis, quantitative measurements of myocardial perfusion as obtained from PET-MPI remain altered in areas initially affected by inflammation. CMR = cardiac magnetic resonance; PET = positron emission tomography; LGE = late gadolinium enhancement

Development and validation of characterization methods for Lipidots® Multifunctional Platform: a step towards industrial transfer

Lipidots® technology has thrived towards a versatile nanodelivery platform for designing and producing a series of nanoproducts for in vivo diagnostic, in vivo imaging, activated or non-activated targeted drug delivery. In order to ensure quality of final products, characterization as nanotherapeutics is a key parameter. Thus, we are seeking to implement and validate a panel of characterization methods significantly suitable for Lipidots®. More particularly, we have investigated the lipid quantification, the drug/dye encapsulation, release kinetics and leakage to anticipate the nanocarrier behavior in biological media