Pressure Suit Research Articles

Manipulation of Printing Direction and Temperature on the Mechanical Properties and Shape Recovery of Thermoplastic Polyurethane 4D‐Printed Polymer‐Textile Composites

ABSTRACTIn recent years, textile practitioners have utilized polyurethane (PU) SMPs to develop 4D printed polymer‐textile composites (4DP PTCs) which have distinct mechanical properties. However, little attention has been paid to combining the effects of extrusion direction and temperature of individual polymer layers on the mechanical properties and shape performance of 4DP PTCs. Hence this study explores the effects of such conditions through the development of thermo‐responsive 4DP PTCs composed of thermoplastic polyurethane (TPU) with a Shore hardness of 70A and 82A, respectively, PU SMP, and a nylon substrate. This study finds that the mechanical and shape performance of 4DP PTCs can be manipulated via varying the extrusion temperature and direction. Weft direction specimens showed greater stiffness (0.19 GPa) and shape fixity (up to 99.56%) whilst warp showed higher flexibility (0.10 GPa) and better shape recovery (up to 96.58%). Hence, 4DP PTCs can be selectively stiffened for applications that is, pressure suits and soft robotics that require enhanced stiffness in specific direction of movement, enabling further development of shape shifting textiles with complex surfaces and structures.

Feasibility study of carbon-fiber reinforced polymer linerless pressure vessel tank

Composite pressure vessels are used in aerospace engineering for storing fluids such as propellants, nitrogen, and oxygen. They are also used in life-support systems, High-performance pressure suits for astronauts, Helium Tanks for Balloons and Airships. Among many types of composites, Carbon fiber composites uses have been increasing due to its high strength to weight ratio, high thermal expansion, corrosion, fatigue and impact resistance and design flexibility. In order to improve the volume of the pressure vessel, the liner-less concept is tried. This increased volume efficiency is crucial in aerospace applications where space is at a premium and maximizing storage capacity within limited dimensions is important. Not only the volume efficiency, but also the Reduced Permeability Concerns, Enhanced Durability and Longevity, better thermal continuity and simplified manufacturing process make this research significant in the area of pressure vessel. This research paper deals with the fabrication and development of a cylinder without a lining. The test sample was subjected to several tests: tensile test, impact, shear test (3P Bending), leak test and Pressure test. The test sample was capable of withstanding 20 Bars without failure. The numerical results were also performed and compared with the experimental results. The difference was only 3%. Unsymmetrical dimethyl hydrazine (UDMH) AND red-fuming nitric acid can both be stored in this cylinder (RFNA). Unlike traditional composite overwrapped pressure vessels, the liner-less composite tanks rely completely on the composite shell to act as a permeation barrier as well as handling all pressure and environmental loads. The absence of a liner eliminates the potential for delamination or failure at the interface between the liner and the composite material.

Decontamination Validation of the BSL-4 Chemical Disinfectant Deluge Shower System.

Positive pressure breathing-air-fed protective suits are used in biosafety level 4 (BSL-4) containment laboratories as personal protective equipment to protect workers from high-consequence pathogens. However, even with the use of primary containment devices, the exterior surfaces of these suits could potentially become contaminated with those pathogens and result in their inadvertent removal from containment. To address the risk of such pathogens escaping from containment via contaminated protective suits, these suits are decontaminated in a disinfectant chemical shower situated in an anteroom prior to exiting the BSL-4 laboratory. Properly diluted chemical disinfectants such as Micro-Chem Plus™ (MCP) or peracetic acid are used for this purpose. However, whether these suits are properly decontaminated during the chemical shower process needs to be validated. The purpose of this study was to develop a suit decontamination validation method for the BSL-4 chemical showers using a risk group 2 (RG2) surrogate virus for the high consequence pathogens that are handled in the BSL-4 laboratories. Here, we evaluated the efficacy of a 5% MCP shower using coupons made from different parts of protective suits (suit fabric, visor, boot, vinyl tape) laden with a dried-on mixture of vesicular stomatitis virus in tripartite organic soil load. This validation study demonstrated that a chemical deluge shower procedure using 5% MCP for 2 min followed by a 3-min water rinse was successful in decontaminating the positive pressure suits that were experimentally contaminated with the live RG2 virus. This offers valuable insights into the rigor of the decontamination process being undertaken in the BSL-4 laboratory chemical showers.

A suite of selective pressures supports the maintenance of alleles of a Drosophila immune peptide.

The innate immune system provides hosts with a crucial first line of defense against pathogens. While immune genes are often among the fastest evolving genes in the genome, in Drosophila , antimicrobial peptides (AMPs) are notable exceptions. Instead, AMPs may be under balancing selection, such that over evolutionary timescales multiple alleles are maintained in populations. In this study, we focus on the Drosophila antimicrobial peptide Diptericin A, which has a segregating amino acid polymorphism associated with differential survival after infection with the Gram-negative bacteria Providencia rettgeri . Diptericin A also helps control opportunistic gut infections by common Drosophila gut microbes, especially those of Lactobacillus plantarum . In addition to genotypic effects on gut immunity, we also see strong sex-specific effects that are most prominent in flies without functional diptericin A . To further characterize differences in microbiomes between different diptericin genotypes, we used 16S metagenomics to look at the microbiome composition. We used both lab reared and wild caught flies for our sequencing and looked at overall composition as well as the differential abundance of individual bacterial families. Overall, we find flies that are homozygous for one allele of diptericin A are better equipped to survive a systemic infection from P. rettgeri , but in general have a shorter lifespans after being fed common gut commensals. Our results suggest a possible mechanism for the maintenance of genetic variation of diptericin A through the complex interactions of sex, systemic immunity, and the maintenance of the gut microbiome.

Spacesuit contact with wearer: Analysis and visualization

Spacesuits are pressurized garments used in space missions to protect crewmembers from the hazards of space. The wearer moves the suit through contact on the interior of the suit with their body. This contact between the suit and body is a critical factor for the fit, mobility, and comfort of the spacesuit. Part of the utility of spacesuits is providing a pressurized environment needed for astronauts to survive. This pressurization turns the spacesuit into a semi rigid enclosure around the wearer, changing how the suit interacts with the body inside. To better understand the spacesuit-wearer contact, a study was performed wherein test subjects from Johnson Space Center's (JSC) spacesuit test subject pool wore the Extravehicular Mobility Unit (EMU) spacesuit in a variety of configurations, including with and without suit pressurization, and held seven different poses. While holding each pose, the test subject reported the intensity and location of their perceived contact with the suit. This data was converted to a binary contact/no contact variable then analyzed to determine the effect that pressurization and pose had on perceived contact. As a result, overall contact trends can be understood and applied to the design of future spacesuit systems.

Contemporary Wildfires Not More Severe Than Historically: More Fire of All Severities Needed to Sustain and Adapt Western US Dry Forests as Climate Changes

Fire-adapted dry forests and nearby communities both need to be sustained as climate changes. Wildfires have increased in the ~25.5 million ha of dry forests in the western US, but are wildfires already more severe than historical (preindustrial) wildfires, warranting suppression, or is more fire needed? Recent research suggests that a higher percentage are more severe, but is this from more high-severity fire (≥70% mortality) or simply less lower-severity fire? To resolve this question, I compared government fire-severity data from 2000–2020 with corresponding government Landfire historical data, representing the last few centuries. The fire rotation (expected time to burn across an area of interest) for high-severity fire was 477 years recently versus 255 years historically, a deficit, not a surplus. High-severity fire would need to increase 1.9 times to equal historical rates. Thus, reducing high-severity fire through fuel reductions is fire suppression, which has significant well-known adverse ecological impacts. These include reductions in (1) natural burn patches, snags, and non-forest openings, that favor diverse fire-adapted species, and (2) landscape heterogeneity that can limit future disturbances and enhance landscape ecological processes. Even larger deficits were in moderate (4.4 times) and low (5.8 times) fire severities. However, if only these lower severities were restored, the high-severity percentage would correspondingly be reduced to low levels. All fire severities are needed to provide a variety of post-fire settings that favor a broad suite of selection pressures and adaptations to emerging climate. This paper shows that to sustain and adapt dry forests and nearby communities to fire and climate change, the billions spent on fuel reductions to reduce high-severity fire can be redirected to protecting the built environment, fostering both safe and sustainable dry forests and human communities.

The History and Possibilities of British Space Suits

The paper surveys, firstly, the history of pressure suit and space suit construction in Britain, and gives the locations of historic suits that could be reverse-engineered. Secondly, the requirements for space suits in the “New Space” era are considered. Thirdly, the work currently being done in Britain on space suits is considered, together with the possibilities for space suits as products that could be manufactured in the United Kingdom for domestic use and for export. Keywords: Pressure Suits, Space Suits, Extra-Vehicular Activity

ADAPTATION OF WUK-90 HIGH ALTITUDE PRESSURE SUITS FOR REHABILITATION PURPOSES

Abstract: Integrating discoveries in military technology into civilian applications represents one of the most common combinations, since these include the technologies developed to, among other things, improve the bodily functions in extreme conditions. In addition, aviation technology is characterized by such parameters as lightness, ergonomics and durability. Adaptation of flight or space suits represents the application of solutions that in their original purpose were dedicated to enhance human capabilities under altered pressure and gravitational conditions. These suits, when properly adjusted, can be used in the rehabilitation of patients with neurological or orthopaedic deficits. The purpose of this publication is to show the most commonly adapted solutions based on HAP suits and space suits, as well as to demonstrate the process of adapting HAP (High Altitude Protection) suits of WUK 90 type (Type 90 High Altitude Pressure Suits) for therapy purposes. In rehabilitation applications, these suits are suitable for adaptation in therapy where the technical parameters of the devices allow to explore completely different therapeutic possibilities. Such devices, however, require adaptation to the needs of disabled people with orthopaedic injuries or mental disorders and specific conditions for rehabilitation, as was the case with the WUK suit, which after introducing technical modifications and adaptation solutions was given the name R-WUK (abbreviated from the Polish name “Rehabilitacyjny Wysokościowy Ubiór Kompensacyjny” (Rehabilitation High Altitude Pressure Suit).

Operationalising ODEMM risk assessment for Integrated Ecosystem Assessment scoping: Complexity vs. manageability

Integrated Ecosystem Assessments (IEA) require consideration of the full suite of pressures and impacts affecting ecosystems. However, capacity limitations often severely limit our ability to do everything that we want or ‘should’ do, outside of short-term fully-funded focused research projects. In order to make IEA a reality in many contexts, priority consideration has to be given to how to achieve such comprehensive assessments. Ecoregions and Large Marine Ecosystems (LMEs) have been identified as potential management units, however these large areas encompass diverse habitats, and multiple nations with diverse human communities and use of marine environments, and a multitude of different management strategies. In this context, how can we make IEA an operational tool that can be applied at such high-level in a comparable, yet regionally-relevant adaptable approach? This paper outlines the demonstration and adaptation of an established risk assessment approach (Options for Delivering Ecosystem-Based Marine Management: ODEMM) to a rapid risk scoping tool, and how this approach has been applied using open source common analytical tools to improve operationality in both the Mission Atlantic project and the International Council for the Exploration of the Seas (ICES) Integrated Ecosystem Assessment Working Groups. Furthermore, a hierarchical approach is detailed that allows the integration of different levels of detail into a common format. The resulting assessments are then ground-truthed with stakeholders to identify issues, omissions, potential conflicts, and key areas of interest for the next steps of the IEA process.

Wild microbiomes of striped plateau lizards vary with reproductive season, sex, and body size

Long-term studies of animal microbiomes under natural conditions are valuable for understanding the effects of host demographics and environmental factors on host-associated microbial communities, and how those effects interact and shift over time. We examined how the cloacal microbiome of wild Sceloporus virgatus (the striped plateau lizard) varies under natural conditions in a multi-year study. Cloacal swabs were collected from wild-caught lizards across their entire active season and over three years in southeastern Arizona, USA. Analyses of 16S rRNA data generated on the Illumina platform revealed that cloacal microbiomes of S. virgatus vary as a function of season, sex, body size, and reproductive state, and do so independently of one another. Briefly, microbial diversity was lowest in both sexes during the reproductive season, was higher in females than in males, and was lowest in females when they were vitellogenic, and microbiome composition varied across seasons, sexes, and sizes. The pattern of decreased diversity during reproductive periods with increased sociality is surprising, as studies in other systems often suggest that microbial diversity generally increases with sociality. The cloacal microbiome was not affected significantly by hibernation and was relatively stable from year to year. This study highlights the importance of long term, wide-scale microbiome studies for capturing accurate perspectives on microbiome diversity and composition in animals. It also serves as a warning for comparisons of microbiomes across species, as each may be under a different suite of selective pressures or exhibit short-term variation from external or innate factors, which may differ in a species-specific manner.

Hydration status during commercial saturation diving measured by bioimpedance and urine specific gravity.

Excessive fluid loss triggered by hyperbaric pressure, water immersion and hot water suits causes saturation divers to be at risk of dehydration. Dehydration is associated with reductions in mental and physical performance, resulting in less effective work and an increased risk of work-related accidents. In this study we examined the hydration status of 11 male divers over 19 days of a commercial saturation diving campaign to a working depth of 74 m, using two non-invasive methods: Bioelectrical impedance analysis (BIA) and urine specific gravity (USG). Measurements were made daily before and after bell runs, and the BIA data was used to calculated total body water (TBW). We found that BIA and USG were weakly negatively correlated, probably reflecting differences in what they measure. TBW was significantly increased after bell runs for all divers, but more so for bellmen than for in-water divers. There were no progressing changes in TBW over the 19-day study period, indicating that the divers’ routines were sufficient for maintaining their hydration levels on short and long term.

Use of R-WUK pressure suits in the therapy of patients with autism and Asperger syndrome: a preliminary report

Pressure suits are used primarily to protect a pilot against increased G-forces and adverse effects of atmospheric pressure at high altitudes. However, pressure suits can also potentially be used for kinesitherapy in patients with orthopaedic, neurological and cognitive deficits, including in those with Asperger syndrome or autism. For this reason, pressure suits have been adapted for therapeutic purposes (rehabilitation). These suits have been named R-WUK. Results obtained in a pilot group show additional possibilities for the application of R-WUK suits in autism therapy and provide a different perspective on the problem of autism spectrum disorder therapy. The innovativeness of this approach is based on the fact that it does not involve any psychological, educational or pharmacological therapies; instead, it employs kinesitherapy with a system that primarily creates physical effects: the suit exerts pressure on the patient’s tissues using pneumatic mechanisms. The present approach also involves the use of physiotherapy methods such as PNF, NDT/Bobath and Stand&Go. As a result of the study intervention, significant changes were observed in the patients’ functioning and behaviour. The changes were so significant that it can be concluded that patients who have undergone R-WUK suit therapy function as neurotypical individuals. A low number of subjects in the study group does not allow one to make a definitive determination that all individuals with autism or Asperger syndrome will undergo similar changes in functioning as a result of the suit therapy.

Use of R-WUK pressure suits in the therapy of patients with autism and Asperger syndrome: a preliminary report

Pressure suits are used primarily to protect a pilot against increased G-forces and adverse effects of atmospheric pressure at high altitudes. However, pressure suits can also potentially be used for kinesitherapy in patients with orthopaedic, neurological and cognitive deficits, including in those with Asperger syndrome or autism. For this reason, pressure suits have been adapted for therapeutic purposes (rehabilitation). These suits have been named R-WUK. Results obtained in a pilot group show additional possibilities for the application of R-WUK suits in autism therapy and provide a ifferent perspective on the problem of autism spectrum disorder therapy. The innovativeness of this approach is based on the fact that it does not involve any psychological, educational or pharmacological therapies; instead, it employs kinesitherapy with a system that primarily creates physical effects: the suit exerts pressure on the patient’s tissues using pneumatic mechanisms. The present approach also involves the use of physiotherapy methods such as PNF, NDT/Bobath and Stand&Go. As a result of the study intervention, significant changes were observed in the patients’ functioning and behaviour. The changes were so significant that it can be concluded that patients who have undergone R-WUK suit therapy function as neurotypical individuals. A low number of subjects in the study group does not allow one to make a definitive determination that all individuals with autism or Asperger syndrome will undergo similar changes in functioning as a result of the suit therapy.

Using interview surveys and multispecies occupancy models to inform vertebrate conservation.

Species distribution data are an essential biodiversity variable requiring robust monitoring to inform wildlife conservation. Yet, such data remain inherently sparse because of the logistical challenges of monitoring biodiversity across broad geographic extents. Surveys of people knowledgeable about the occurrence of wildlife provide an opportunity to evaluate species distributions and the ecology of wildlife communities across large spatial scales. We analyzed detection histories of 30 vertebrate species across the Western Ghats biodiversity hotspot in India, obtained from a large-scale interview survey of 2318 people who live and work in the forests of this region. We developed a multispecies occupancy model that simultaneously corrected for false-negative (non-detection) and false-positive (misidentification) errors that interview surveys can be prone to. Using this model, we integrated data across species in composite analyses of the responses of functional species groups (based on disturbance tolerance, diet, and body mass traits) to spatial variation in environmental variables, protection, and anthropogenic pressures. We observed a positive association between forest cover and the occurrence of species with low tolerance of human disturbance. Protected areas were associated with higher occurrence for species across different functional groups compared with unprotected lands. We also observed the occurrence of species with low disturbance tolerance, herbivores, and large-bodied species was negatively associated with developmental pressures, such as human settlements, energy production and mining, and demographic pressures, such as biological resource extraction. For the conservation of threatened vertebrates, our work underscores the importance of maintaining forest cover and reducing deforestation within and outside protected areas, respectively. In addition, mitigating a suite of pervasive human pressures is also crucial for wildlife conservation in one of the world's most densely populated biodiversity hotspots.

Efficacy Testing of Personal Protective Filters on Biosafety Level 4 Positive Pressure Suits.

Introduction: Positive pressure breathing air-fed protective suits from three vendors are commonly used in biosafety level 4 (BSL-4) laboratories: they are Dover Chemturion suits (ILC Dover, DE), Delta suits (Honeywell Safety, NC), and HVO suits (HVO-ISSI-Deutschland GmbH, Germany). To address the potential risk of infectious agents being introduced through the supplied breathing air stream, some suit manufacturers incorporate protective filters on the suits themselves. However, these integrated filters are not amenable to in situ testing for efficacy verification. We have been using external filters from Matheson USA on the positive pressure suits since our BSL-4 laboratories were commissioned two decades ago. As part of our BSL-4 protective suit management program, we test these filters before them being put into use, and annually thereafter. In the past few years, we have observed these filters failing at a higher rate, as high as two out of three of the new filters tested at one point. Objective: The purpose of this study was to procure personal protective filters from other sources and validate their efficacy long-term. Methods: Filters from Respirex, HVO, and Honeywell were validated for filter integrity and filter loading. Results: Respirex filters performed well during the initial testing and periodic testing thereafter. Regular testing of the Respirex filters has now been ongoing for 30 months with continued successful performance. Conclusion: Filters from Respirex are a suitable option to protect personnel wearing positive pressure suits in BSL-4 laboratories.

Evaluating Lumbar Shape Deformation With Fabric Strain Sensors

To better study human motion inside the space suit and suit-related contact, a multifactor statistical model was developed to predict torso body shape changes and lumbar motion during suited movement by using fabric strain sensors that are placed on the body. Physical interactions within pressurized space suits can pose an injury risk for astronauts during extravehicular activity (EVA). In particular, poor suit fit can result in an injury due to reduced performance capabilities and excessive body contact within the suit during movement. A wearable solution is needed to measure body motion inside the space suit. An array of flexible strain sensors was attached to the body of 12 male study participants. The participants performed specific static lumbar postures while 3D body scans and sensor measurements were collected. A model was created to predict the body shape as a function of sensor signal and the accuracy was evaluated using holdout cross-validation. Predictions from the torso shape model had an average root mean square error (RMSE) of 2.02 cm. Subtle soft tissue deformations such as skin folding and bulges were accurately replicated in the shape prediction. Differences in posture type did not affect the prediction error. This method provides a useful tool for suited testing and the information gained will drive the development of injury countermeasures and improve suit fit assessments. In addition to space suit design applications, this technique can provide a lightweight and wearable system to perform ergonomic evaluations in field assessments.

Decompression Sickness Treatment Using a Pressure Suit After Loss of Spacecraft Atmosphere.

BACKGROUND: Loss of spacecraft atmosphere (LOA) during Earth-Moon transit may require up to 144 h of pressure suit operations. This work investigates the feasibility of DCS treatment in this paradigm and discusses the operational and engineering implications.METHODS: Three scenarios of LOA-induced DCS were considered: a permanent LOA secondary to a 0.25-in (0.64 cm) hole (unrecoverable cabin leak), a transient LOA, and a permanent LOA with early suit over-pressurization (beyond suit specification). Each was simulated in the context of the current Orion spacecraft operational concept with regards to atmosphere and anticipated cabin depress profile. Probability of DCS symptom resolution (P(SR)) was estimated using the previously derived Hypobaric DCS Treatment Model, with ΔP calculated from a Three Region Well-Stirred Tissue (3RWT) bubble dynamics model. Analysis was conducted and analogies drawn from experiences with the development and testing of the Orion Crew Survival System (OCSS).RESULTS: Maintaining 8 psia at 100% Fio₂ following LOA resulted in an eventual halt and regression of bubble growth with a P(SR) of 87% (at 8 h, time to symptom onset (Ts) = 105 min, with ambulation). If cabin atmosphere was not restored and psia dropped to 4.3, bubble growth returned, but again eventually slowed and regressed over time (P(SR) = 75% at 21 h). If the leak is repaired within the 8-h period, 8 psid (psia = 22.7) resulted in P(SR) of greater than 95%. Similarly, if the suit was over-pressurized (12 psid/psia) within 3 h after LOA, P(SR) exceeded 95%.DISCUSSION: A launch/entry pressure suit represents a contingency option for DCS management in the event of LOA.Greene MR, Jacobs SE. Decompression sickness treatment using a pressure suit after loss of spacecraft atmosphere. Aerosp Med Hum Perform. 2020; 91(7):571-577.

Nest-site selection and breeding success of two neotropical austral migrant birds in a semiarid forest: A comparison of sites with and without livestock

Understanding the mechanisms underpinning nest-site selection offers novel insights about selective forces shaping the breeding ecology of birds, and provides vital information for conservation planning. We evaluated and compared nest-site selection and breeding success of Vermilion Flycatchers (VEFL) and Fork-tailed Flycatchers (FTFL) in areas with and without livestock in the Espinal biome of La Pampa Province, Argentina. VEFL selected nest sites with greater tree cover, whereas FTFL nested in taller trees with narrower trunks. We found a weak positive effect of nest height, diameter of nest-support branches and the absence of livestock on VEFL nest survival, and a weak positive effect of nest orientation on FTFL nest survival. However, although some habitat characteristics varied between the two areas, nest site characteristics of both species in areas with and without livestock did not differ significantly. The nest survival was 12.7% for VEFL and 28.7% for FTFL, and did not differ significantly between these two flycatchers. The breeding ecology of these birds has likely been molded by a broad suite of selective pressures, such as severe weather, brood parasites and predators that characterize habitats in central Argentina.

Do differences in developmental mode shape the potential for local adaptation?

Future climate change is leading to the redistribution of life on Earth as species struggle to cope with rising temperatures. Local adaptation allows species to become locally optimized and persist despite environmental selection, but the extent to which this occurs in nature may be limited by dispersal and gene flow. Congeneric marine gastropod species (Littorina littorea and L.saxatilis) with markedly different developmental modes were collected from across a latitudinal thermal gradient to explore the prevalence of local adaptation to temperature. The acute response of metabolic rate (using oxygen consumption as a proxy) to up-ramping and down-ramping temperature regimes between 6°C and 36°C was quantified for five populations of each species. The highly dispersive L.littorea exhibited minimal evidence of local adaptation to the thermal gradient, with no change in thermal optimum (Topt ) or thermal breadth (Tbr ) and a decline in maximal performance (max ) with increasing latitude. In contrast, the direct developing L.saxatilis displayed evidence of local optimization, although these varied idiosyncratically with latitude, suggesting a suite of selective pressures may be involved in shaping thermal physiology in this relatively sedentary species. Our results show that the biogeography of thermal traits can differ significantly between related species, and show that interpopulation differences in thermal performance do not necessarily follow simple patterns that may be predicted based on latitudinal changes in environmental temperatures. Further research is clearly required to understand the mechanisms that can lead to the emergence of local adaptation in marine systems better and allow improved predictions of species redistribution in response to climate change.

Mobile Lower Body Negative Pressure Suit as an Integrative Countermeasure for Spaceflight.

BACKGROUND: Persistent headward fluid shift and mechanical unloading cause neuro-ocular, cardiovascular, and musculoskeletal deconditioning during long-term spaceflight. Lower body negative pressure (LBNP) reintroduces footward fluid shift and mechanical loading.METHODS: We designed, built, and tested a wearable, mobile, and flexible LBNP device (GravitySuit) consisting of pressurized trousers with built-in shoes to support ground reaction forces (GRF) and a thoracic vest to distribute load to the entire axial length of the body. In eight healthy subjects we recorded GRF under the feet and over the shoulders (Tekscan) while assessing cardiovascular response (Nexfin) and footward fluid shift from internal jugular venous cross-sectional area (IJVa) using ultrasound (Terason).RESULTS: Relative to normal bodyweight (BW) when standing upright, increments of 10 mmHg LBNP from 0 to 40 mmHg while supine induced axial loading corresponding to 0%, 13 ± 3%, 41 ± 5%, 75 ± 11%, and 125 ± 22% BW, respectively. Furthermore, LBNP reduced IJVa from 1.12 ± 0.3 cm² to 0.67 ± 0.2, 0.50 ± 0.1, 0.35 ± 0.1, and 0.31 ± 0.1 cm², respectively. LBNP of 30 and 40 mmHg reduced cardiac stroke volume and increased heart rate while cardiac output and mean arterial pressure were unaffected. During 2 h of supine rest at 20 mmHg LBNP, temperature and humidity inside the suit were unchanged (23 ± 1°C; 47 ± 3%, respectively).DISCUSSION: The flexible GravitySuit at 20 mmHg LBNP comfortably induced mechanical loading and desired fluid displacement while maintaining the mobility of hips and knee joints. The GravitySuit may provide a feasible method to apply low-level, long-term LBNP without interfering with daily activity during spaceflight to provide an integrative countermeasure.Petersen LG, Hargens A, Bird EM, Ashari N, Saalfeld J, Petersen JCG. Mobile lower body negative pressure suit as an integrative countermeasure for spaceflight. Aerosp Med Hum Perform. 2019; 90(12):993-999.