LDEF yaw and pitch angle estimates

Quantification of the LDEF yaw and pitch misorientations is crucial to the knowledge of atomic oxygen exposure of samples placed on LDEF. Video camera documentation of the LDEF spacecraft prior to grapple attachment, atomic oxygen shadows on experiment trays and longerons, and a pinhole atomic oxygen camera placed on LDEF provided sources of documentation of the yaw and pitch misorientation. Based on uncertainty-weighted averaging of data, the LDEF yaw offset was found to be 8.1 plus or minus 0.6 degrees, allowing higher atomic oxygen exposure of row 12 than initially anticipated. The LDEF pitch angle offset was found to be 0.8 plus or minus 0.4 degrees, such that the space end was tipped forward toward the direction of travel. The resulting consequences of the yaw and pitch misorientation of LDEF on the atomic oxygen fluence is a factor of 2.16 increase for samples located on row 12, and a factor of 1.18 increase for samples located on the space end compared to that which would be expected for perfect orientation

The use of plasma ashers and Monte Carlo modeling for the projection of atomic oxygen durability of protected polymers in low Earth orbit

The results of ground laboratory and in-space exposure of polymeric materials to atomic oxygen has enabled the development of a Monte Carlo computational model which simulates the oxidation processes of both environments. The cost effective projection of long-term low-Earth-orbital durability of protected polymeric materials such as SiO(x)-coated polyimide Kapton photovoltaic array blankets will require ground-based testing to assure power system reliability. Although silicon dioxide thin film protective coatings can greatly extend the useful life of polymeric materials in ground-based testing, the projection of in-space durability based on these results can be made more reliable through the use of modeling which simulates the mechanistic properties of atomic oxygen interaction, and replicates test results in both environments. Techniques to project long-term performance of protected materials, such as the Space Station Freedom solar array blankets, are developed based on ground laboratory experiments, in-space experiments, and computational modeling

Monte Carlo modeling of atomic oxygen attack of polymers with protective coatings on LDEF

Characterization of the behavior of atomic oxygen interaction with materials on the Long Duration Exposure Facility (LDEF) assists in understanding of the mechanisms involved. Thus the reliability of predicting in-space durability of materials based on ground laboratory testing should be improved. A computational model which simulates atomic oxygen interaction with protected polymers was developed using Monte Carlo techniques. Through the use of an assumed mechanistic behavior of atomic oxygen interaction based on in-space atomic oxygen erosion of unprotected polymers and ground laboratory atomic oxygen interaction with protected polymers, prediction of atomic oxygen interaction with protected polymers on LDEF was accomplished. However, the results of these predictions are not consistent with the observed LDEF results at defect sites in protected polymers. Improved agreement between observed LDEF results and predicted Monte Carlo modeling can be achieved by modifying of the atomic oxygen interactive assumptions used in the model. LDEF atomic oxygen undercutting results, modeling assumptions, and implications are presented

Atomic oxygen interaction at defect sights in protective coatings on polymers flown on LDEF

Although the Long Duration Exposure Facility (LDEF) has exposed materials with a fixed orientation relative to the ambient low-Earth-orbital environment, arrival of atomic oxygen is angularly distributed as a result of the atomic oxygen's high temperature Maxwellian velocity distribution and the LDEF's orbital inclination. Thus, atomic oxygen entering defects in protective coatings on polymeric surfaces can cause wider undercut cavities than the size of the defect in the protective coating. Because only a small fraction of atomic oxygen reacts upon first impact with most polymeric materials, secondary reactions with lower energy thermally accommodated atomic oxygen can occur. The secondary reactions of scattered and/or thermally accommodated atomic oxygen also contribute to widening the undercut cavity beneath the protective coating defect. As the undercut cavity enlarges, exposing more polymer, the probability of atomic oxygen reacting with underlying polymeric material increases because of multiple opportunities for reaction. Thus, the effective atomic oxygen erosion yield for atoms entering defects increases above that of the unprotected material. Based on the results of analytical modeling and computational modeling, aluminized Kapton multilayer insulation exposed to atomic oxygen on row 9 lost the entire externally exposed layer of polyimide Kapton, yet based on the results of this investigation, the bottom surface aluminum film must have remained in place, but crazed. Atomic oxygen undercutting at defect sites in protective coatings on graphite epoxy composites indicates that between 40 to 100 percent of the atomic oxygen thermally accommodates upon impact, and that the reaction probability of thermally accommodated atomic oxygen may range from 7.7 x 10(exp -6) to 2.1 x 10(exp -3), depending upon the degree of thermal accommodation upon each impact

Atomic Oxygen Durability Evaluation of Protected Polymers Using Thermal Energy Plasma Systems

The durability evaluation of protected polymers intended for use in low Earth orbit (LEO) has necessitated the use of large-area, high-fluence, atomic oxygen exposure systems. Two thermal energy atomic oxygen exposure systems which are frequently used for such evaluations are radio frequency (RF) plasma ashers and electron cyclotron resonance plasma sources. Plasma source testing practices such as ample preparation, effective fluence prediction, atomic oxygen flux determination, erosion measurement, operational considerations, and erosion yield measurements are presented. Issues which influence the prediction of in-space durability based on ground laboratory thermal energy plasma system testing are also addressed

A descriptive analysis of human milk dispensed by the Leipzig Donor Human Milk Bank for neonates between 2012 and 2019

BackgroundHuman milk banking has become an important aspect of Nutritional medicine. It is not just about the provision of mother’s own milk (MOM) or donor human milk (DHM) in the hospital, but also a strategy to encourage breastfeeding in the clinical setting and beyond.ObjectiveTo describe the feeding patterns of hospitalised infants including human milk dispensed by the Leipzig Donor Human Milk Bank (LMB).DesignA descriptive analysis of daily data on milk feeds dispensed by LMB for hospitalised infants distinguishing between MOM or DHM, either fresh or frozen, and raw/pasteurised milk from 2012–2019.ResultsWe included 2,562 infants with median hospitalisation of 23 days, for whom human milk was dispensed on median 76% of those days and other nutrition on the remaining days. Raw MOM and raw DHM comprised 52% and 8% of the dispensed milk, respectively. Dispensing exclusive DHM instead of MOM for at least one full day was required for 55% of the infants, mostly at the beginning but also later during hospitalisation. Exclusive raw DHM was dispensed on at least 1 day for 37% of the infants, in different birthweight strata <1,000 g: 10%, 1,000-1500 g: 11%, 1,500-2500 g: 13% and > 2,500 g: 3%. At discharge, MOM was dispensed for more than 60% of the infants.ConclusionDuring an infant’s hospital stay, LMB dispenses various human milk feeds with interspersed DHM resulting in complex intra-individual and time-variant feeding patterns. LMB dispenses raw MOM and especially raw DHM with the intention to retain the properties of human milk unlike a diet containing pasteurised DHM and/or formula. Although raw DHM comprises a small percentage of all dispensed milk, raw DHM is dispensed for a substantial portion of infants. Our results document that dispensing raw DHM, is possible in routine settings

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

”Man måste se snygg ut - hela tiden” : en kvalitativ studie av tonårstjejer och deras relation till kläder

The purpose of this study was to investigate a group of teenage girls and their relation to clothes by using the theories about habitus and different types of capital by the French sociologist Pierre Bourdieu. We have used semiotics since we also wanted to know what clothes symbolized for our respondents. The questions were therefore: 1. How is a group of teenage girls who go to school in Stockholm city influenced by their habitus and symbolical capital in their attitude and relation to clothes? 2. What do the clothes symbolize for these girls? We have interviewed four sixteen year old girls who all study at a high school in Stockholm city. Our conclusion is that each girls habitus and different assets of capitals have an influence on her attitude and relation to clothes. For our respondents the clothes symbolized status, economical capital and to look attractive to others.Avsikten med denna uppsats var att undersöka en grupp tonårstjejer och deras relation till kläder utifrån den franske sociologen Pierre Bourdieus teorier om habitus och olika former av kapital. Vi har också använt oss utav semiotiken då vi även ville veta vad kläder symboliserar för våra respondenter. Våra frågeställningar blev därför: 1. Hur influeras en grupp tonårstjejer som går i skolan i Stockholm av sitt habitus och symboliska kapital när det gäller deras inställning och relation till kläder? 2. Vad symboliserar kläder för dessa tjejer? För att besvara dessa frågor har vi intervjuat fyra sextonåriga tjejer som alla studerar vid ett gymnasium i Stockholms innerstad. Vår slutsats är att det habitus och olika tillgångar av kapital hos respektive tjej vi intervjuade påverkade hennes klädbruk. Kläderna symboliserade status, ekonomiskt kapital och att se attraktiv ut inför andra