Controlled Environmental Effects on Creep Test Data of Woven Fabric Webbings for Inflatable Space Modules

eveloping technologies for proposed lunar and Mars space exploration missions. Enhanced habitation sy g studied as potential habitats due to their inherent low mass and small launch volume. One goal of inflatable module research is quantification of the safe-life and end-of-life creep-strain spectrum. Full-scale pressurized inflatable modules are large, costly, and difficult to experimentally study. Therefore, material subcomponents are often studied as an alternative. An experimental thermally controlled long-term creep study of VectranTM webbings for application to inflatable modules is presented. Vectran fibers have high strength and low creep properties. High strength webbing materials are desirable for the load bearing restraint layer of inflatable modules because they are strong, flexible, and lightweight. Characterization of the creep behavior, safe-life, and end-of- life of webbing specimens will help quantify comparable life properties for inflatable modules. Several experimental multiple-year creep studies of webbing specimens in uncontrolled thermal environments have been conducted at NASA Langley Research Center. Experimental data obtained exhibits the classic creep-strain curve due to load, coupled with unique sinusoidal variation due to variation in temperature and humidity over daily and annual time periods. Results also have indicated that specimens fail within a year if the applied load is greater than 50 percent of the rated load. The primary goal of this study is to eliminate thermal effects from the creep data for a group of webbing specimens, and to allow uncontrolled thermal effects to influence the creep data of a second group of webbing specimens. Comparison of both sets of data will define how temperature influences creep data. A unique creep test facility was fabricated to facilitate the generation and comparison of the two sets of data. The facility consists of five creep test stands with an integrated heating and cooling system, and four creep test stands exposed to external environmental or ambient conditions. The facility contains displacement, temperature, humidity, and load sensors. Test specimens consist of one- inch wide, 48-inch long Vectran webbings rated at 12,500 pounds-per-inch. Experimental thermally controlled creep-strain data has been generated for two groups of webbing specimens. Applied load for all test stands was above 9000 lbs and greater than 50 percent of the rated load. Temperatures varied between 58F and 83F for the four test stands exposed to ambient conditions. Associated creep data exhibited the classic creep- strain profiles. The temperature was set to 72F for the five test stands in the controlled temperature environment. Creep data for tests with temperature control also exhibited the classic strain profiles. Data indicated that if the load is greater n thermal effects do not manifest. Therefore, creep tests with loads less than 50 percent of the rated load are planned for in the near future

Environmental Effects on Long Term Displacement Data of Woven Fabric Webbings Under Constant Load for Inflatable Structures

An experimental study of the effects of environmental temperature and humidity conditions on long-term creep displacement data of high strength Kevlar and VectranTM woven fabric webbings under constant load for inflatable structures is presented. The restraint layer of an inflatable structure for long-duration space exploration missions is designed to bear load and consists of an assembly of high strength webbings. Long-term creep displacement data of webbings can be utilized by designers to validate service life parameters of restraint layers of inflatable structures. Five groups of high-strength webbings were researched over a two year period. Each group had a unique webbing length, load rating, applied load, and test period. The five groups consisted of 1.) 6K Vectran webbings loaded to 49% ultimate tensile strength (UTS), 2.) 6K Vectran webbings loaded to 55% UTS, 3.) 12.5K Vectran webbings loaded to 22% UTS, 4.) 6K Kevlar webbings loaded to 40% and 43% UTS, and 5.) 6K Kevlar webbings loaded to 48% UTS. Results show that all webbing groups exhibit the initial two stages of three of a typical creep curve of an elastic material. Results also show that webbings exhibit unique local wave patterns over the duration of the test period. Data indicate that the local pattern is primarily generated by daily variations in relative humidity values within the test facility. Data indicate that after a three to six month period, where webbings reach a steady-state creep condition, an annual sinusoidal displacement pattern is exhibited, primarily due to variations in annual mean temperature values. Data indicates that variations in daily temperature values and annual mean humidity values have limited secondary effects on creep displacement behavior. Results show that webbings in groups 2 and 5 do not exhibit well defined annual displacement patterns because the magnitude of the applied loads cause large deformations, and data indicate that material yielding within a webbing tends to neutralize the annual sinusoidal displacement pattern. Study indicates that applied load, environmental effects, mechanical strength, coefficient of thermal expansion, and hygroscopic properties of webbings are fundamental requirements for quantifying accurate creep displacements and behaviors over multiple year time periods. Results from a study of the environmental effects on long-term creep displacement data of Kevlar and Vectran woven webbings are presented to increase the knowledge base of webbing materials and to enhance designs of inflatable space structures for long-duration space missions

Optical Fiber Distributed Sensing Structural Health Monitoring (SHM) Strain Measurements Taken During Cryotank Y-Joint Test Article Load Cycling at Liquid Helium Temperatures

This paper outlines cryogenic Y-joint testing at Langley Research Center (LaRC) to validate the performance of optical fiber Bragg grating strain sensors for measuring strain at liquid helium temperature (-240 C). This testing also verified survivability of fiber sensors after experiencing 10 thermal cool-down, warm-up cycles and 400 limit load cycles. Graphite composite skins bonded to a honeycomb substrate in a sandwich configuration comprised the Y-joint specimens. To enable SHM of composite cryotanks for consideration to future spacecraft, a light-weight, durable monitoring technology is needed. The fiber optic distributed Bragg grating strain sensing system developed at LaRC is a viable substitute for conventional strain gauges which are not practical for SHM. This distributed sensing technology uses an Optical Frequency Domain Reflectometer (OFDR). This measurement approach has the advantage that it can measure hundreds of Bragg grating sensors per fiber and the sensors are all written at one frequency, greatly simplifying fiber manufacturing. Fiber optic strain measurements compared well to conventional strain gauge measurements obtained during these tests. These results demonstrated a high potential for a successful implementation of a SHM system incorporating LaRC's fiber optic sensing system on the composite cryotank and other future cryogenic applications

Recommendation for post-exposure prophylaxis after potential exposure to herpes b virus in Germany

Although the risk of a herpes B virus (Cercopithecine herpes virus 1) infection is low, the clinical course of the infectious disease is generally unfavourable. A high safety standard can be achieved if people with professional contact to primates apply proper organisational, technical and personal safety precautions. The risk can be considerably reduced if animal keepers, laboratory assistants and scientists receive adequate information about the pathology of herpes B virus and are well trained in the necessary procedures and the precautions. For this reason, comprehensive and regular training, information and instruction must be provided to all primate workers and to laboratory workers who come into contact with potentially infectious material. After potential contamination, the risk for the affected worker must be assessed immediately and post-exposure chemoprophylaxis performed if necessary. This necessitates internal risk assessment. An interdisciplinary group of experts has developed an action plan for Germany

Effects of pressure-controlled intermittent coronary sinus occlusion on regional ischemic myocardial function

Pressure-controlled intermittent coronary sinus occlusion has been reported to reduce infarct size in dogs with coronary artery occlusion, possibly because of increased ischemic zone perfusion and washout of toxic metabolites. The influence of this intervention on regional myocardial function was investigated in open and closed chest dogs. In six open chest dogs with severe stenosis of the left anterior descending coronary artery and subsequent total occlusion, a 10 minute application of intermittent coronary sinus occlusion increased ischemic myocardial segment shortening from 5.5 ± 1.2 to 8.2 ± 2.6% (NS) and from −0.1 ± 2.1 to 2.3 ± 1.2% (NS), respectively.In eight closed chest anesthetized dogs, intermittent coronary sinus occlusion was applied for 2.5 hours between 30 minutes and 3 hours of intravascular balloon occlusion of the proximal left anterior descending coronary artery. Standardized two-dimensional echocardio-graphic measurements of left ventricular function were performed to derive systolic sectional and segmental fractional area changes in five short-axis cross sections of the left ventricle. Fractional area change in all the severely ischemic segments (< 5% systolic wall thickening) was −4.0 ± 4.7% at 30 minutes after occlusion, and increased with subsequent 60 and 150 minutes of treatment to 13.1 ± 3.3 and 7.0 ± 3.3%, respectively (p < 0.05). At the most extensively involved low papillary muscle level of the ventricle, regional ischemic fractional area change was increased by intermittent coronary sinus occlusion between 30 and 180 minutes of coronary occlusion from −0.4 ± 0.1 to 14.4 ± 4% (p < 0.05), whereas a further deterioration was noted in untreated dogs with coronary occlusion.Continuous arterial and coronary venous blood density measurements were performed in seven open chest dogs to determine the influence of pressure-controlled intermittent coronary sinus occlusion on ischemic myocardial washout. The arteriovenous density gradient was 0.16 ± 0.05 g/Iiter during coronary artery occlusion, and decreased to 0.05 ± 0.08 g/liter (p < 0.05) as a result of the intervention, suggesting a significant fluid washout from the myocardium. It is concluded that pressure-controlled intermittent coronary sinus occlusion provides recovery of cardiac function and that this benefit might be associated with enhanced ischemic zone washout

Serotonin 5-HT2A receptors underlie increased motor behaviors induced in dopamine-depleted rats by intrastriatal 5-HT2A/2C agonism

ABSTRACT Gene expression studies have suggested that dopamine (DA) depletion increases the sensitivity of striatal direct pathway neurons to the effects of serotonin (5-HT) via the 5-HT 2 receptor. The present study examined the possible influence(s) of 5-HT 2A or 5-HT 2C receptor-mediated signaling locally within the striatum on motor behavior triggered by 5-HT 2 receptor agonism in the neonatal DA-depleted rat. Male Sprague-Dawley rats were treated with 6-hydroxydopamine (6-OHDA; 60 g in 5 l per lateral ventricle) on postnatal day 3 to achieve near-total DA depletion bilaterally. Sixty days later, sham-operated (saline-injected) or 6-OHDA-treated rats were challenged with the 5-HT 2A/2C agonist DOI [(Ϯ)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane] or saline either by systemic treatment or bilateral intrastriatal infusion. Motor behavior was quantified for 60 min after agonist injection using computerized activity monitors. Systemic DOI treatment (0.2 or 2.0 mg/kg i.p.) was more effective in inducing motor activity in the DA-depleted group compared with intact controls. Intrastriatal DOI infusion (1.0 or 10.0 g/side) also produced a significant rise in motor activity in the DA-depleted group during the 30-to 60-min period of behavioral analysis but did not influence behavior in intact animals. The effects of intrastriatal DOI infusion were blocked by intrastriatal coinfusion of the 5-HT 2 antagonist ketanserin (1. A loss of dopamine (DA) transmission to the rodent striatum during early postnatal development results in a compensatory increase in serotonin (5-HT) innervation to the dorsal striatum Several studies indicate that 5-HT 2A receptors are positioned to mediate the influences of enhanced 5-HT signaling in the DA-depleted striatum. First, 5-HT release agents and 5-HT 2 receptor agonists gain potency in inducing striatal preprotachykinin (PPT; encodes substance P and neurokini

Long Term Displacement Data of Woven Fabric Webbings Under Constant Load for Inflatable Structures

Inflatable modules for space applications offer weight and launch volume savings relative to current metallic modules. Limited data exist on the creep behavior of the restraint layer of inflatable modules. Long-term displacement and strain data of two high strength woven fabric webbings, Kevlar and Vectran, under constant load is presented. The creep behavior of webbings is required by designers to help determine service life parameters of inflatable modules. Four groups of different webbings with different loads were defined for this study. Group 1 consisted of 4K Kevlar webbings loaded to 33% ultimate tensile strength and 6K Vectran webbings loaded to 27% ultimate tensile strength, group 2 consisted of 6K Kevlar webbings loaded to 40% and 43% ultimate tensile strength, and 6K Vectran webbings loaded to 50% ultimate tensile strength, group 3 consisted of 6K Kevlar webbings loaded to 52% ultimate tensile strength and 6K Vectran webbings loaded to 60% ultimate tensile strength, and group 4 consisted of 12.5K Kevlar webbings loaded to 22% ultimate tensile strength, and 12.5K Vectran webbings loaded to 22% ultimate tensile strength. The uniquely designed test facility, hardware, displacement measuring devices, and test data are presented. Test data indicate that immediately after loading all webbings stretch an inch or more, however as time increases displacement values significantly decrease to fall within a range of several hundredth of an inch over the remainder of test period. Webbings in group 1 exhibit near constant displacements and strains over a 17-month period. Data acquisition was suspended after the 17th month, however webbings continue to sustain load without any local webbing damage as of the 21st month of testing. Webbings in group 2 exhibit a combination of initial constant displacement and subsequent increases in displacement rates over a 16-month period. Webbings in group 3 exhibit steady increases in displacement rates leading to webbing failure over a 3-month period. Five of six webbings experienced local damage and subsequent failure in group 3. Data from group 4 indicates increasing webbing displacements over a 7-month period. All webbings in groups 1, 2, and 4 remain suspended without any local damage as of the writing of this paper. Variations in facility temperatures over test period seem to have had limited effect on long-term webbing displacement data

Wet, wild and convivial : past, present and future contributions of Australia’s ocean pools to surf, beach, pool and body cultures and recreational coasts

I investigated the past, present and possible futures of Australia’s ocean pools, over a hundred public seawater pools sited on rocky surfcoasts, so that waves wash over their walls. My interdisciplinary analysis informed by actor-­‐network theory explored their contributions to surf, beach, pool and body cultures and recreational coasts. Ocean pools have since the nineteenth century been far more significant in the surf, beach, pool and body cultures of Australia and South Africa, than in those of Britain and the United States. Most of Australia’s ocean pools lie within state of New South Wales, and my work strengthens the case for recognising Australian and NSW ocean pools as having distinct collective identities and affinities with their South African counterparts. Ocean pools are sites of social and environmental learning that challenge efforts to establish human mastery over wild natures and depictions of coastal environments as mere stages for enacting human activities unconstrained by non-­‐human nature. They also challenge the notion that people prefer to swim and bathe at patrolled beaches or in private or public pools far less wild than an ocean pool. They are evidence that supervision by suitably trained and equipped lifeguards or lifesavers is not the only or the most satisfactory way to adequately safeguard bathers and swimmers from the dangers of the sea. Australia’s ocean pools demonstrate that regardless of race, class, gender, age or ability, people can and do make themselves at home in pools shared convivially with wild nature and well-­‐suited for sustained, unsupervised recreation and sport on rocky surfcoast. Ocean pools serve as places of refuge, therapeutic and restorative environments, adventure playgrounds, convivial public spaces, visually appealing cultural landscapes, brands, icons and symbols. Australia’s ocean pools are unified by their sites, their affordances and core actor-­‐ networks linked to their fundamental and enduring identity as ‘wild but safe enough surfside pools’. Rocky shores and coastal waters characterised by surf, sharks and rips are among the most persistent macro-­‐actors in these networks that include bathers, swimmers, tourism and transport networks, news media, local councils and progress associations. Australian ocean pools that gained a further identity as ‘public pools for competition and carnivals’ acquired additional actor-­‐networks strongly linked since the late nineteenth century to amateur swimming clubs and schools, and since the twentieth century to surf lifesaving clubs and winter swimming clubs. Those ocean pools nevertheless, remained predominately recreational facilities. As other types of public pools became more affordable, Australia’s ocean pools remained popular despite gaining new identities as an ‘unusually hazardous type of public pool’ and ‘a type of facility no longer created’. The growing threats to ocean pools and their actor-­‐networks are a further unifying factor. As sport and recreation venues cultivating healthy, convivial relationships with wild nature and possessing unrealised potential as centres for community engagement, learning and research, ocean pools are worth emulating on other rocky shores and in other public places. My work strengthens efforts to sustain and create ocean pools and supports further studies on seawater pools and their actor-­‐networks

Comparison of Autoclave and Out-of-Autoclave Composites

The National Aeronautics and Space Administration (NASA) Exploration Systems Mission Directorate initiated an Advanced Composite Technology Project through the Exploration Technology Development Program in order to support the polymer composite needs for future heavy lift launch architectures. As an example, the large composite dry structural applications on Ares V inspired the evaluation of autoclave and out-of-autoclave (OOA) composite materials. A NASA and industry team selected the most appropriate materials based on component requirements for a heavy lift launch vehicle. Autoclaved and OOA composites were fabricated and results will highlight differences in processing conditions, laminate quality, as well as initial room temperature thermal and mechanical performance. Results from this study compare solid laminates that were both fiber-placed and hand-laid. Due to the large size of heavy-lift launch vehicle composite structures, there is significant potential that the uncured composite material or prepreg will experience significant out-life during component fabrication. Therefore, prepreg out-life was a critical factor examined in this comparison. In order to rigorously test material suppliers recommended out-life, the NASA/Industry team extended the out-time of the uncured composite prepreg to values that were approximately 50% beyond the manufacturers out-time limits. Early results indicate that the OOA prepreg composite materials suffered in both composite quality and mechanical property performance from their extended out-time. However, the OOA materials performed similarly to the autoclaved composites when processed within a few days of exposure to ambient "shop" floor handling. Follow on studies evaluating autoclave and OOA aluminum honeycomb core sandwich composites are planned