Performance Characterization and Simulation of Amine-Based Vacuum Swing Sorption Units for Spacesuit Carbon Dioxide and Humidity Control

Controlling carbon dioxide (CO2) and water (H2O) vapor concentrations in a space suit is critical to ensuring an astronauts safety, comfort, and capability to perform extra-vehicular activity (EVA) tasks. Historically, this has been accomplished using lithium hydroxide (LiOH) and metal oxide (MetOx) canisters. Lithium hydroxide is a consumable material that requires priming with water before it becomes effective at removing carbon dioxide. MetOx is regenerable through a power-intensive thermal cycle but is significantly heavier on a volume basis than LiOH. As an alternative, amine-based vacuum swing beds are under aggressive development for EVA applications. The vacuum swing units control atmospheric concentrations of both CO2 and H2O through fully-regenerative process. The current concept, referred to as the rapid cycle amine (RCA), has resulted in numerous laboratory prototypes. Performance of these prototypes have been assessed experimentally and documented in previous reports. To support developmental e orts, a first principles model has also been established for the vacuum swing sorption technology. For the first time in several decades, a major re-design of Portable Life Support System (PLSS) for the extra-vehicular mobility unit (EMU) is underway. NASA at Johnson Space Center built and tested an integrated PLSS test bed of all subsystems under a variety of simulated EVA conditions of which the RCA prototype played a significant role. The efforts documented herein summarize RCA test performance and simulation results for single and variable metabolic rate experiments in an integrated context. In addition, a variety of off-nominal tests were performed to assess the capability of the RCA to function under challenging circumstances. Tests included high water production experiments, degraded vacuum regeneration, and deliberate valve/power failure and recovery

BRB System Out-of-Plane Considerations

This paper describes a simple method for BRB system design considering BRB stability and frame out-ofplane deformation effects. The method seeks to prevent yielding in the BRB system except for in the core within the BRB restrainer/casing, and it uses standard equations with which engineers are familiar. The method discourages brace/gusset plate regions which are too flexible, where instability may occur as a result of axial force, or which are too stiff, where yielding may occur due to out-of-plane frame deformations thereby compromising the performance in later in-plane deformation cycles. The need to explicitly consider column twist restraint in the design procedure is emphasized

Autophagy upregulation and loss of NF-kB in oxidative stress-related immunodeficient SAMP8 mice

Aged spleens from senescence-accelerated prone mice 8 (SAMP8) and senescence-accelerated resistant mice 1 (SAMR1) were examined to determine whether sex or melatonin had an effect on oxidative stress-related immune impairments. We observed that the immunosenescence of SAMP8 mice was associated with a redox imbalance, leading to an age-related increase in oxidative damage, resulting from a decrease in antioxidant defense and protease activity. Moreover, increased apoptotic cell death, a decrease in proliferative activity and the loss of NF-kB activation were also related to the immunodeficiency seen in SAMP8 compared to SAMR1 mice. Females demonstrated higher oxidative stress-related alterations in the immune response, and subsequent, melatonin treatment provided the best protective effects. Pathways involved in autophagy were upregulated in SAMP8 as an adaptive response to oxidative stress, in an attempt to rescue the cell from increased apoptosis and age-related immunodeficiency. However, the NF-kB signaling and autophagic processes were unaffected by treatment with melatonin. Therefore, we propose a key role for NF-kB signaling and autophagy in the oxidative stress-related immunosenescent spleens of SAMP8 mice

Ultrasound-Assisted Melt Extrusion of Polymer Nanocomposites

A review of the latest developments in ultrasound-assisted melt extrusion of polymer nanocomposites is presented. In general, the application of ultrasound waves during melt extrusion of polymer in the presence of nanoparticles results in a more homogeneous dispersion of the nanoparticles in the polymer matrix. In spite of this, a lack of understanding in the field has hindered the development of this processing technique. Based on the analysis of literature on the field, key aspects are identified for a better understanding of the physical and chemical effects of ultrasound waves and the fabrication of polymer nanocomposites by means of melt extrusion

An Interactive Web-Based Lethal Means Safety Decision Aid for Suicidal Adults (Lock to Live): Pilot Randomized Controlled Trial

BACKGROUND: Counseling to reduce access to lethal means such as firearms and medications is recommended for suicidal adults but does not routinely occur. We developed the Web-based Lock to Live (L2L) decision aid to help suicidal adults and their families choose options for safer home storage. OBJECTIVE: This study aimed to test the feasibility and acceptability of L2L among suicidal adults in emergency departments (EDs). METHODS: At 4 EDs, we enrolled participants (English-speaking, community-dwelling, suicidal adults) in a pilot randomized controlled trial. Participants were randomized in a 13:7 ratio to L2L or control (website with general suicide prevention information) groups and received a 1-week follow-up telephone call. RESULTS: Baseline characteristics were similar between the intervention (n=33) and control (n=16) groups. At baseline, many participants reported having access to firearms (33/49, 67%), medications (46/49, 94%), or both (29/49, 59%). Participants viewed L2L for a median of 6 min (IQR 4-10 min). L2L also had very high acceptability; almost all participants reported that they would recommend it to someone in the same situation, that the options felt realistic, and that L2L was respectful of values about firearms. In an exploratory analysis of this pilot trial, more participants in the L2L group reported reduced firearm access at follow-up, although the differences were not statistically significant. CONCLUSIONS: The L2L decision aid appears feasible and acceptable for use among adults with suicide risk and may be a useful adjunct to lethal means counseling and other suicide prevention interventions. Future large-scale studies are needed to determine the effect on home access to lethal means. TRIAL REGISTRATION: ClinicalTrials.gov NCT03478501; https://clinicaltrials.gov/ct2/show/NCT03478501