Gravitational Conditions Research Articles

3D Clinorotation Affects Drug Sensitivity of Human Ovarian Cancer Cells

Numerous studies have reported that gravity alteration displays a remarkable influence on the biological processes of cancer cells. Therefore, gravity-related experiments have become a promising method of improving knowledge in the field of cancer biology and may be useful to detect remarkable implications for future cancer treatment. Taking this concept further, we used a 3D clinostat (3D-C; 10 rpm of changing direction) to analyse the effect of short-term exposure to simulated microgravity (sμg) on cisplatin sensitivity of drug resistant human ovarian cancer cells SKOV-3. This allowed us to investigate whether altered gravity affects drug susceptibility of cancer cells. Our studies revealed that sμg exposure affects SKOV-3 cells morphology and drug efficiency. We observed the altered cell shape, the presence of membrane blebbing and lamellipodia as well as the lack of filopodia when the cells had been cultured on 3D-C for 2 h. Cytotoxicity, cell death and cell cycle assays showed an increased percentage of apoptotic cells and G0/G1 cell cycle arrest after exposure on the 3D-C with cisplatin in comparison to the static control, non clinorotated cells. Cell proliferation and migration were altered after the exposure to sμg as well. Our studies suggest that the altered gravity conditions affected cellular mechanisms involved in cisplatin resistance, resulting in higher sensitivity of cancer cells to the chemotherapeutic. The investigation and clarification of these results may be a crucial step toward improving our understanding of the relationship between cellular resistance to chemotherapy and the response to altered gravitational conditions.

Comparison of Electromyographic Activity During Hip Extension Exercises Under Gravitational or Inertial Loading Conditions.

Hamstring injury prevention programs include strengthening, especially eccentric exercises using both gravitational and inertial loading. Inertial exercises are characterized by eccentric contractions of high intensity and velocity. This study aimed to analyze the muscular activation of the biceps femoris (BF), semitendinosus (ST), gluteus maximus (GM), and gracilis (GC) muscles during hip extension (HE) exercises performed under both gravitational and inertial loading conditions. Inertial training would generate a greater activation of HE muscles than gravitational training. Cross-sectional study. Level 4. Fifteen resistance-trained men performed the unilateral straight knee bridge (SKB), 45° of HE, and stiff-leg deadlift (SDL) exercises under gravitational and inertial loading conditions. Concentric and eccentric phases were identified with a linear encoder. Differences between load types, exercises, and their interaction were examined to establish the electromyographic (EMG) activity of each muscle and BF/ST ratio. In the concentric phase, inertial loading showed a higher normalized EMG than gravitational loading for BF, ST, and GM. SKB and HE activated BF and ST between 9.6% and 24.3% more than SDL. In the eccentric phase, the inertial modality achieved greater GM activation than the gravitational form (18.1%). BF activation was increased with HE and SKB as compared with SDL (24.4% and 16.4%, respectively), while ST activation was likewise enhanced with HE as compared with SDL (15.1%). Inertial training is more effective than gravitational training for the concentric activation of the hamstring muscles while SDL showed lower hamstring activation than HE and SKB. Therefore, HE and SKB with inertial loading should be taken into account in hamstring training programs. Inertial training is more effective than gravitational training for the concentric activation of the hamstring muscles. HE and SKB with inertial loading should be taken into account in hamstring training programs.

Stability of Antimicrobial Drug Molecules in Different Gravitational and Radiation Conditions in View of Applications during Outer Space Missions.

The evolution of different antimicrobial drugs in terrestrial, microgravity and hypergravity conditions is presented within this review, in connection with their implementation during human space exploration. Drug stability is of utmost importance for applications in outer space. Instabilities may be radiation-induced or micro-/hypergravity produced. The antimicrobial agents used in space may have diminished effects not only due to the microgravity-induced weakened immune response of astronauts, but also due to the gravity and radiation-altered pathogens. In this context, the paper provides schemes and procedures to find reliable ways of fighting multiple drug resistance acquired by microorganisms. It shows that the role of multipurpose medicines modified at the molecular scale by optical methods in long-term space missions should be considered in more detail. Solutions to maintain drug stability, even in extreme environmental conditions, are also discussed, such as those that would be encountered during long-duration space exploratory missions. While the microgravity conditions may not be avoided in space, the suggested approaches deal with the radiation-induced modifications in humans, bacteria and medicines onboard, which may be fought by novel pharmaceutical formulation strategies along with radioprotective packaging and storage.

Microbially-Enhanced Vanadium Mining and Bioremediation Under Micro- and Mars Gravity on the International Space Station.

As humans explore and settle in space, they will need to mine elements to support industries such as manufacturing and construction. In preparation for the establishment of permanent human settlements across the Solar System, we conducted the ESA BioRock experiment on board the International Space Station to investigate whether biological mining could be accomplished under extraterrestrial gravity conditions. We tested the hypothesis that the gravity (g) level influenced the efficacy with which biomining could be achieved from basalt, an abundant material on the Moon and Mars, by quantifying bioleaching by three different microorganisms under microgravity, simulated Mars and Earth gravitational conditions. One element of interest in mining is vanadium (V), which is added to steel to fabricate high strength, corrosion-resistant structural materials for buildings, transportation, tools and other applications. The results showed that Sphingomonas desiccabilis and Bacillus subtilis enhanced the leaching of vanadium under the three gravity conditions compared to sterile controls by 184.92 to 283.22%, respectively. Gravity did not have a significant effect on mean leaching, thus showing the potential for biomining on Solar System objects with diverse gravitational conditions. Our results demonstrate the potential to use microorganisms to conduct elemental mining and other bioindustrial processes in space locations with non-1 × g gravity. These same principles apply to extraterrestrial bioremediation and elemental recycling beyond Earth.

Additive Manufacturing Under Lunar Gravity and Microgravity

Mankind is setting to colonize space, for which the manufacturing of habitats, tools, spare parts and other infrastructure is required. Commercial manufacturing processes are already well engineered under standard conditions on Earth, which means under Earth’s gravity and atmosphere. Based on the literature review, additive manufacturing under lunar and other space gravitational conditions have only been researched to a very limited extent. Especially, additive manufacturing offers many advantages, as it can produce complex structures while saving resources. The materials used do not have to be taken along on the mission, they can even be mined and processed on-site. The Einstein-Elevator offers a unique test environment for experiments under different gravitational conditions. Laser experiments on selectively melting regolith simulant are successfully conducted under lunar gravity and microgravity. The created samples are characterized in terms of their geometry, mass and porosity. These experiments are the first additive manufacturing tests under lunar gravity worldwide.

Study of mouse behavior in different gravity environments

Many experiments have analyzed the effect of the space environment on various organisms. However, except for the group-rearing of mice in space, there has been little information on the behavior of organisms in response to gravity changes. In this study, we developed a simple Active Inactive Separation (AIS) method to extract activity and inactivity in videos obtained from the habitat cage unit of a space experiment. This method yields an activity ratio as a ratio of ‘activity’ within the whole. Adaptation to different gravitational conditions from 1g to hypergravity (HG) and from microgravity (MG) to artificial 1g (AG) was analyzed based on the amount of activity to calculate the activity ratio and the active interval. The result for the activity ratios for the ground control experiment using AIS were close to previous studies, so the effectiveness of this method was indicated. In the case of changes in gravity from 1g to HG, the ratio was low at the start of centrifugation, recovered sharply in the first week, and entered a stable period in another week. The trend in the AG and HG was the same; adapting to different gravity environments takes time.

Experimental Investigation of non‐periodic oscillations in a surface tension driven flow around a bubble

AbstractThermocapillary convection around an air bubble under a heated wall is experimentally investigated under gravitational conditions. The flow is basically studied through temperature fluctuation plots near the bubble periphery, which is subjected to an upward flow driving temperature gradient. This study illuminates the thermocapillary‐buoyancy convective flow behaviour within the regime of non‐periodic oscillations. Moreover, the fluid flow is qualitatively categorized according to the transient behaviour of the thermocapillary vortex boundary line around the bubble using the shadowgraph technique. A low viscous silicone oil as test fluid restricts reaching higher temperature gradients to avoid the formation of undesired vapour bubbles. However, pursuing the experiments under high pressures allowed reaching higher temperature gradients in order to achieve the non‐periodic flow regime. Both periodic and chaotic oscillations of the liquid flow around the bubble were recorded. They were distinguished from each other through the periodicity of the visualized thermocapillary vortex boundary line movements. The recording of temperature fluctuations at positions near the bubble during a time period Δt demonstrated the thermocapillary fluid flow behaviour at different Marangoni‐numbers Mg.

Сателлитные клетки скелетных мышц в условиях гравитационной разгрузки

It is known that skeletal muscles have a high degree of plasticity. Gravitational unloading has a strong impact on the structural and functional organization of the postural muscles. Skeletal muscle has a unique ability to repair damage. Recovery (regeneration) of muscles is carried out by satellite cells. Myosatellites are quiescent mononuclear cells (G0 phase of the cell cycle) located at the periphery of the muscle fiber. When muscles are damaged, satellite cells are activated, they participate in proliferation and give rise to new satellite cells and myoblasts. Differentiated myoblasts can fuse with muscle fibers during muscle hypertrophy and regeneration, as well as with each other to form new muscle fibers. Studies of the effect of gravitational unloading on muscle satellite cells are few. This review to consider of the influence of gravitational unloading on the pool of muscle satellite cells and the mechanisms of skeletal muscle regeneration after injury. Based on the literature data, the authors found, that the mechanisms underlying the change in the regenerative potential of muscles under gravitational unloading conditions are poorly understood. The authors highlight the need for further studies of the regenerative potential of satellite cells under microgravity conditions.

Downward Annular Flow of Air–Oil–Water Mixture in a Vertical Pipe

The paper presents the results of a study concerned with the hydrodynamics of an annular downward multiphase flow of gas and two mutually non-mixing liquids through a vertical pipe with a diameter of 12.5 mm. The air, oil and water were used as working media in this study with changes in superficial velocities in the ranges of jg = 0.34–52.5 m/s for air, jo = 0.000165–0.75 m/s for oil, and jw = 0.02–2.5 m/s for water, respectively. The oil density and viscosity were varied within the ranges of ρo = 859–881 kg/m3 and ηo = 29–2190 mPas, respectively. The research involved the identification of multiphase flow patterns and determination of the void fraction of the individual phases. New flow patterns have been identified and described for the gravitational flow conditions of a two-phase water–oil liquid and a three-phase air–water–oil flow. New flow regime maps and equations for the calculation of air, oil and water void fractions have been developed. A good conformity between the calculated and measured values of void fraction were obtained. The map for the oil–water–air three-phase flow is valid for the following conditions: j3P = 0.35–53.4 m/s (velocity of three-phase mixture) and oil in liquid concentration βo* = 0.48–94% (oil in liquid concentration). In the case of a downward annular oil–water two-phase flow, this map is valid for liquid mixture velocity jl = 0.052–2.14 m/s and βo* = 0.48–94%.

Gravitational radiation condition at infinity with a positive cosmological constant

Gravitational waves have been directly detected and astronomical observations indicate that our Universe has a positive cosmological constant $\Lambda$. Nevertheless, a theoretical gauge-invariant notion of gravitational waves arriving at infinity (escaping from the space-time) in the presence of a positive $\Lambda$ has been elusive. We find the answer to this long-standing gravitational puzzle and present a geometric, gauge-invariant radiation condition at infinity.

Annihilation-to-nothing: a quantum gravitational boundary condition for the Schwarzschild black hole

The interior of a static Schwarzschild metric can be written in terms of two functions, similar to some models of anisotropic cosmology. With a suitable choice of canonical variables, we solve the Wheeler-DeWitt equation (WDW) inside the horizon of a Schwarzschild black hole. By imposing classicality near the horizon, and requiring boundedness of the wave function, we get a rather generic solution of the WDW equation, whose steepest-descent solution, i.e., the ridge of the wave function, coincides nicely with the classical trajectory. However, there is an ambiguity in defining the arrow of time which leads to two possible interpretations—(i) if there is only one arrow of time, one can infer that the steepest-descent of the wave function follows the classical trajectory throughout: coming from the event horizon and going all the way down to the singularity, while (ii) if there are two different arrows of time in two separate regimes, it can be inferred that the steepest-descent of the wave function comes inwards from the event horizon in one region while it moves outwards from the singularity in the other region, and there exists an annihilation process of these two parts of the wave function inside the horizon. Adopting the second interpretation could shed light on the information loss paradox: as time goes on, probabilities for histories that include black holes and singularities decay to zero and eventually only trivial geometries dominate.

Dressing the weightless body: Subjective verticality and the disoriented experience of dress in microgravity

Design practice has historically been constrained by the assumption that designed objects, including clothing, will be made and worn in Earth gravity. The notion that designed objects have an upright state has influenced common approaches to design, including the tendency towards depiction and presentation of designed objects in elevation view, which, for fashion, is frequently understood in terms of silhouette. However, those who have experienced weightlessness, either in space travel or on board reduced-gravity aircraft, describe a post-gravity experience that prompts them to revisit these assumptions and consider the extent to which future commercial space travel will liberate creative practitioners to operate at all angles and orientations. As we enter the commercial space age, fashion will be increasingly worn in a variety of gravitational conditions, and the dressed body will therefore be encountered at a variety of orientations, showcasing views of garments that are not often encountered on Earth, and that are therefore often overlooked by fashion designers. This article responds to descriptions of the post-gravity experience by identifying the need to consider alternative views of the clothed body, and consequently to define garments without reference to the silhouette in fashion design for the new commercial space age.

Microgravity and Hypergravity Induced by Parabolic Flight Differently Affect Lumbar Spinal Stiffness.

The objective of this study was to determine the response of the lumbar spinal motor control in different gravitational conditions. This was accomplished by measuring indicators of lumbar motor control, specifically lumbar spinal stiffness, activity of lumbar extensor and flexor muscles and lumbar curvature, in hypergravity and microgravity during parabolic flights. Three female and five male subjects participated in this study. The mean age was 35.5 years (standard deviation: 8.5 years). Spinal stiffness of the L3 vertebra was measured using impulse response; activity of the erector spinae, multifidi, transversus abdominis, and psoas muscles was recorded using surface electromyography; and lumbar curvature was measured using distance sensors mounted on the back-plate of a full-body harness. An effect of gravity condition on spinal stiffness, activity of all muscles assessed and lumbar curvature (p’s < 0.007) was observed (Friedman tests). Post hoc analysis showed a significant reduction in stiffness during hypergravity (p < 0.001) and an increase in stiffness during microgravity (p < 0.001). Activity in all muscles significantly increased during hypergravity (p’s < 0.001). During microgravity, the multifidi (p < 0.002) and transversus abdominis (p < 0.001) increased significantly in muscle activity while no significant difference was found for the psoas (p = 0.850) and erector spinae muscles (p = 0.813). Lumbar curvature flattened in hypergravity as well as microgravity, albeit in different ways: during hypergravity, the distance to the skin decreased for the upper (p = 0.016) and the lower sensor (p = 0.036). During microgravity, the upper sensor showed a significant increase (p = 0.016), and the lower showed a decrease (p = 0.005) in distance. This study emphasizes the role of spinal motor control adaptations in changing gravity conditions. Both hypergravity and microgravity lead to changes in spinal motor control. The decrease in spinal stiffness during hypergravity is interpreted as a shift of the axial load from the spine to the pelvis and thoracic cage. In microgravity, activity of the multifidi and of the psoas muscles seems to ensure the integrity of the spine. Swiss (BASEC-NR: 2018-00051)/French “EST-III” (Nr-ID-RCB: 2018-A011294-51/Nr-CPP: 18.06.09).

Vegetative and reproductive growth of Arabidopsis under microgravity conditions in space.

We have performed a seed-to-seed experiment in the cell biology experiment facility (CBEF) installed in the Kibo (Japanese Experiment Module) in the International Space Station. The CBEF has a 1 × g compartment on a centrifuge and a microgravity compartment, to investigate the effects of microgravity on the vegetative and reproductive growth of Arabidopsis thaliana (L.) Heynh. Seeds germinated irrespective of gravitational conditions after water supply on board. Thereafter, seedlings developed rosette leaves. The time of bolting was slightly earlier under microgravity than under space 1 × g. Microgravity enhanced the growth rate of peduncles as compared with space 1 × g or ground control. Plants developed flowers, siliques and seeds, completing their entire life cycle during 62-days cultivation. Although the flowering time was not significantly affected under microgravity, the number of flowers in a bolted plant significantly increased under microgravity as compared with space 1 × g or ground control. Microscopic analysis of reproductive organs revealed that the longitudinal length of anthers was significantly shorter under microgravity when compared with space 1 × g, while the length of pistils and filaments was not influenced by the gravitational conditions. Seed mass significantly increased under microgravity when compared with space 1 × g. In addition, seeds produced in space were found not to germinate on the ground. These results indicate that microgravity significantly influenced the reproductive development of Arabidopsis plants even though Earth's gravitational environment is not absolutely necessary for them to complete their life cycle.

An Interplanetary Mission Design of a Solar Sailing CubeSat to Mars

While solar sailing missions have been developed in the past, orbital solar sailing missions are limited in number. Increasing access to the solar system can be achieved by leveraging the potential of solar sailing spacecraft. A feasibility study is performed to analyse a controlled solar sailing mission to Mars using a CubeSat platform. The proposal to send a solar sailing CubeSat to Mars would be revolutionary in delivering small payloads to the red planet by harnessing the solar radiation pressure emitted from the Sun. By utilising solar sailing and aerocapture techniques in the mission design, the need for chemical propulsion for transfer and capture is greatly reduced, minimising launch mass and maximizing payload mass efficiency.In this study, investigations were carried out as mission analyses in the area of trajectory architecture and subsystem overview for systems available today and in the future. The influence and evolution of trajectories under gravitational and environmental conditions on Mars and the interplanetary transfer were scrutinised individually as relevant restricted dynamic systems. For a chosen insertion orbit, several feasible trajectories to Mars based on different solar sail systems were investigated, including optimised ballistic trajectories and the Sundiver transfer for solar sails. For the interplanetary trajectories, the planetary capture manoeuvre of the spacecraft to a serviceable orbit using aerobraking capture is evaluated. The final trajectory design features minimum-time optimisation for the interplanetary transfer of a solar sailing spacecraft from Earth to Mars. As the selected spacecraft platform is limited to low-thrust solar sailing propulsion, severe performance limitations apply to this mission. This work aims to highlight possible interplanetary trajectories for present and future small satellite platforms despite these limitations by using dynamical orbital simulation models.

Centrifuge modeling of failure behaviors of sandy slope caused by gravity, rainfall, and base shaking

This study focused on slope stability behaviors under different conditions, including gravity, rainfall, and earthquake. The slope models were prepared by mixing sand (80%) and clay (kaolinite, 20%) and compacting at optimum water content. Under the gravitational condition, the model tests were performed with three different directions of a gravel layer embedded into the slope. During the test, the artificial acceleration was gradually increased until slope failure occurred to observe the slope behaviors under rainfall and earthquake. The results indicated that the direction of the gravel layer affected the distribution of water content. Additionally, it was found that the inclination angle was a key factor influencing slope stability. Rainfall intensity played an important role in infiltration water. With regard to the failure wedge, among the three conditions examined, the earthquake condition generated the most significant effect on slope stability. Herein, for evaluating the stability of slopes, the Bishop's method incorporating an inclination angle of a gravel layer and apparent cohesion is introduced.

Convective boiling heat transfer under microgravity and hypergravity conditions

The present paper concerns an experimental investigation of the gravitational effects on subcooled and saturated flow boiling heat transfer in a vertical 3.75 mm diameter aluminum tube, using perfluorohexane as working fluid. Experimental results obtained during parabolic flights are compared with data gathered in the same test facility for normal gravity. Results were obtained for mass velocities of 133, 252, 377 and 428 kg/m2s, heat fluxes up to 106 kW/m2 and vapor qualities up to 0.28. The assessments of prediction methods from literature for flow boiling heat transfer proposed for normal gravitational conditions were evaluated through comparisons of calculated and experimental results. In general, for either a mass velocity of 428 kg/m2s or a vapor quality lower than -0.2, the gravitational effects on the heat transfer coefficient were found as negligible. For lower mass velocities and saturated flow boiling, higher heat transfer coefficients were observed under hypergravity conditions. This behavior was associated to the fact that higher gravitational forces favor bubbles detachment. The method of Kanizawa et al. [1] provided reasonable predictions of the saturated flow boiling results under microgravity and hyper gravity conditions, predicting 100% of the data within an error band of ±30%.

Targeted silencing of miRNA-132-3p expression rescues disuse osteopenia by promoting mesenchymal stem cell osteogenic differentiation and osteogenesis in mice

BackgroundSkeletal unloading can induce severe disuse osteopenia that often occurs in spaceflight astronauts or in patients subjected to prolonged bed-rest or immobility. Previously, we revealed a mechano-sensitive factor, miRNA-132-3p, that is closely related to the osteoblast function. The aim of this study was to investigate whether miRNA-132-3p could be an effective target for treating disuse osteopenia.MethodsThe 2D-clinostat device and the hindlimb-unloaded (HU) model were used to copy the mechanical unloading condition at the cellular and animal levels, respectively. Mimics or inhibitors of miRNA-132-3p were used to interfere with the expression of miRNA-132-3p in bone marrow-derived mesenchymal stem cells (BMSCs) in vitro for analyzing the effects on osteogenic differentiation. The special in vivo antagonists of miRNA-132-3p was delivered to the bone formation regions of HU mice for treating disuse osteopenia by a bone-targeted (AspSerSer)6-cationic liposome system. The bone mass, microstructure, and strength of the hindlimb bone tissue were analyzed for evaluating the therapeutic effect in vivo.ResultsmiRNA-132-3p expression was declined under normal conditions and increased under gravitational mechanical unloading conditions during osteogenic differentiation of BMSCs in vitro. The upregulation of miRNA-132-3p expression resulted in the inhibition of osteogenic differentiation, whereas the downregulation of miRNA-132-3p expression enhanced osteogenic differentiation. The inhibition of miRNA-132-3p expression was able to attenuate the negative effects of mechanical unloading on BMSC osteogenic differentiation. Most importantly, the targeted silencing of miRNA-132-3p expression in the bone tissues could effectively preserve bone mass, microstructure, and strength by promoting osteogenic differentiation and osteogenesis in HU mice.ConclusionThe overexpression of miRNA-132-3p induced by mechanical unloading is disadvantageous for BMSC osteogenic differentiation and osteogenesis. Targeted silencing of miRNA-132-3p expression presents a potential therapeutic target for the prevention and treatment of disuse osteoporosis.

Progress in the solidification of monotectic alloys under the microgravity condition of space

Monotectic alloys or alloys with a miscibility gap in the liquid state are a broad kind of materials. They are especially suitable for the manufacturing of either the in-situ particle composite materials or the composite materials with a core/shell structure and, thus, have a strong industry application background. These alloys, however, have an essential drawback that just the miscibility gap poses problems during solidification. When a single-phase melt of these alloys is cooled into the miscibility gap, it decomposes into two liquids enriched with different components. Generally, the convection flow caused by the gravity and the liquid-liquid phase transformation cause the formation of a phase segregated microstructure when these alloys are solidified under the normal gravitational conditions. Under microgravity condition, the convection flow caused by the gravity and the sediment or floating of the second phase due to the density difference between the components are obviously weakened, it is beneficial for the study of solidification theory of monotectic alloy and the preparation of monotectic alloys composited with a well dispersed microstructure. In recent decades, plenty of efforts have been made to investigate the solidification of monotectic alloys under microgravity conditions, this article will review the research work in this field during the last few decades.

Gravitational corner conditions in holography

Contrary to popular belief, asymptotically anti-de Sitter solutions of gravitational theories cannot be obtained by taking initial data (satisfying the constraints) on a spacelike surface, and choosing an arbitrary conformal metric on the timelike boundary at infinity. There are an infinite number of corner conditions that also must be satisfied where the initial data surface hits the boundary. These are well known to mathematical relativists, but to make them more widely known we give a simple explanation of why these conditions exist and discuss some of their consequences. An example is given which illustrates their power. Some implications for holography are also mentioned.