Hypergravity (HG) and microgravity (MG) modulate Ca2+ entry into the cytosol of cardiomyocytes via both voltage-gated and mechanically gated Ca2+ channels. The last include members of the TRP channel family with TRPM7 being the predominant subtype. We investigated the relationship between changes in TRPM7 channel protein synthesis and the abundance of its corresponding mRNA in cardiomyocytes from rats exposed to HG or MG for 14 days. Using transcriptome sequencing with normalization of "raw reads" by the TPM (Transcripts Per Kilobase Million) method, we found that TRPM7 TPM values significantly increased after HG exposure and significantly decreased after MG. Western blotting of TRPM7 protein levels confirmed a pronounced upregulation under HG and a substantial downregulation under MG. These changes may lead to altered ion conductance through mechanically gated channels in cardiomyocytes.

Abstract The ∼1,600 km‐long, left‐lateral strike‐slip Altyn Tagh fault system defines the northern margin of the Tibetan Plateau, accommodating the India‐Eurasia convergence. While this important fault system has generally been considered to develop along several pre‐existing lithospheric strength discontinuities, its evolution needs further exploration. This study investigates the structural evolution of the Altyn Tagh fault system through physical analog modeling under both normal and hyper gravity conditions, employing four distinct models (M1, M2, M3, and M4) that incorporate various geometries of pre‐existing strength discontinuities. Each model exhibits unique development of fault networks, illustrating the complexity of fault behaviors under different conditions. Model M3, featuring a Z‐shaped pre‐existing strength discontinuity between the hard and soft domains (representing the Tarim—Alxa blocks and the Tibetan Plateau, respectively), effectively replicates key characteristics of the Altyn Tagh fault system, including two prominent sinistral strike‐slip faults (the Altyn Tagh fault and the North Altyn fault), the triangle‐shaped Altyn Shan, and a suite of E‐W striking transpressional faults that have been widely observed on the southern side of the fault system. Our analysis suggests that the Altyn Tagh fault system evolved along complex lithospheric strength discontinuities, resulting in an complex tectonic history characterized by the early activation of the North Altyn fault and subsequent strike‐slip motion along the younger Altyn Tagh Fault. This tectonic reorganization aligns with recent geological findings, underscoring the significant influence of ancient structural configurations on Cenozoic tectonic processes.

We recently reported sex-dependent impairment in cognitive functions in male and female mice exposed for 24 h, 48 h or 15 days to 2G hypergravity (HG). In the present study, we investigated brain functional correlates by analyzing synaptic activity and plasticity in the CA1 area of the hippocampus in both genders of mice previously exposed to 2G for the same duration. This was assessed by electrophysiological extracellular recordings in ex vivo slice preparations. Basal synaptic transmission and glutamate release were unchanged regardless of HG duration. However, plasticity was altered in a sex- and time-specific manner. In males, long-term potentiation (LTP) induced by strong high-frequency stimulation and NMDA receptor (NMDAr) activation was reduced by 26% after 24 h of exposure but recovered at later timepoints. This deficit was reversed by D-serine or glycine, suggesting decreased activation at the NMDAr co-agonist site. In females, LTP deficits (23%) were found only after 15 days following mild theta burst stimulation and were not reversed by D-serine. Long-term depression (LTD) was unaffected in both sexes. This study highlights, for the first time, sex-dependent divergence in the CA1 hippocampal plasticity timeline following 2G exposure. The synaptic changes depend on exposure duration and the stimulation protocol and could underlie the previously observed cognitive deficits.

This study evaluates the effects of hypergravity (HG) on a neurodegenerative model in vitro, looking at how HG influences Tau protein aggregation in Mouse Hippocampal Neuronal Cells (HT22) induced by neurofibrillary tangle seeds. Overall, 50× g significantly, synergistically, reduced the Tau aggregate Area when combined with ERK-inhibitor PD-0325901, correlating with decreased phosphorylation at critical residues pS262 and pS396. These findings suggest HG treatments may help mitigate cytoskeletal damage linked to Tau aggregation.

The new step in space exploration coupled with an exponential increase in the number of astronauts flying in space and preparing future Moon and Mars missions in the coming years will be possible if research and training at different gravity levels is actively pursued. Blue Abyss proposes a versatile approach for astronaut training and research at various gravity levels and in different environments. Blue Abyss is establishing its first research, test and training center in Cleveland, Ohio, USA, with plans to expand to other locations in the USA, Middle-East and the Far-East. The Blue Abyss center will be built around three main axes: (1) A versatile multi-use dive pool with several platforms from 3 to 20 m, a space research area, the Astrolab platform at 12 m, and a 50 m deep shaft; (2) A centrifuge to train astronauts and to study hypergravity physiological effects; and (3) A parabolic flight capability to offer zero, Lunar, Mars, other reduced and hyper gravity accelerations for gravity-related research and training. The ground infrastructure will include classrooms, hypobaric and hyperbaric chambers, and a human performance research center including specialized test and evaluation facilities, microgravity and hypergravity simulators that will be used for physiological studies, rehabilitation and training. A pedagogical and outreach program will offer an interactive, dynamic approach to STEM-related education for students, tomorrow's scientists.

Numerical investigation on laser-induced nanobubble nucleation and dynamics of plasmonic nanoparticles with different structures

Numerical analysis on combustion characteristics of diffusion jet flame under different gravity environments

Thin structural elements such as large-scale covering plates of aerospace protection structures and vertical stabilizers of aircraft are strongly influenced by gravity (and/or acceleration); thus, exploring how the mechanical behaviors of such structures are affected by gravitational field is necessary. Built upon a zigzag displacement model, this study establishes a three-dimensional vibration theory for ultralight cellular-cored sandwich plates subjected to linearly varying in-plane distributed loads (due to, e.g., hyper gravity or acceleration), with the cross-section rotation angle induced by face sheet shearing accounted for. For selected boundary conditions, the theory enables quantifying the influence of core type (e.g., close-celled metal foams, triangular corrugated metal plates, and metal hexagonal honeycombs) on fundamental frequencies of the sandwich plates. For validation, three-dimensional finite element simulations are carried out, with good agreement achieved between theoretical predictions and simulation results. The validated theory is subsequently employed to evaluate how the geometric parameters of metal sandwich core and the mixture of metal cores and composite face sheets influence the fundamental frequencies. Triangular corrugated sandwich plate possesses the highest fundamental frequency, irrespective of boundary conditions. For each type of sandwich plate considered, the presence of in-plane distributed loads significantly affects its fundamental frequencies and modal shapes.

The forces generated by gravity have shaped life on Earth and impact gene expression and morphogenesis during early development. Conversely, disuse on Earth or during spaceflight, reduces normal mechanical loading of organisms, resulting in altered cell and tissue function. Although gravity mechanical loading in adult mammals is known to promote increased cell proliferation and differentiation, little is known about how distinct cell types respond to gravity mechanostimulation during early development. In this study we sought to understand, with single cell RNA-sequencing resolution, how a 60-min pulse of 50 g hypergravity (HG)/5 kPa hydrostatic pressure, influences transcriptomic regulation of developmental processes in the embryoid body (EB) model. Our study included both day-9 EBs and progenitor mouse embryonic stem cells (ESCs) with or without the HG pulse. Single cell t-distributed stochastic neighbor mapping shows limited transcriptome shifts in response to the HG pulse in either ESCs or EBs; this pulse however, induces greater positional shifts in EB mapping compared to ESCs, indicating the influence of mechanotransduction is more pronounced in later states of cell commitment within the developmental program. More specifically, HG resulted in upregulation of self-renewal and angiogenesis genes in ESCs, while in EBs, HG loading was associated with upregulation of Gene Ontology-pathways for multicellular development, mechanical signal transduction, and DNA damage repair. Cluster transcriptome analysis of the EBs show HG promotes maintenance of transitory cell phenotypes in early development; including EB cluster co-expression of markers for progenitor, post-implant epiblast, and primitive endoderm phenotypes with HG pulse but expression exclusivity in the non-pulsed clusters. Pseudotime analysis identified three branching cell types susceptible to HG induction of cell fate decisions. In totality, this study provides novel evidence that ESC maintenance and EB development can be regulated by gravity mechanostimulation and that stem cells committed to a differentiation program are more sensitive to gravity-induced changes to their transcriptome.

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.

Temperature control test of scaled model of high capacity hypergravity centrifuge

Higher g value stimuli (gravitational acceleration more than 1 g and referred as hyper gravity) caused by centrifugation have been shown to inhibit elongation growth of various plants. In the present study, effects of high g values were studied on wheat seeds with and without water medium at the time of exposure to high g values. Wheat seeds (variety: LOK-1) were washed with 0.5% fungicide and then 4-5 times with distilled water (D/W). Seeds were then soaked in D/W for 24 hrs. Two different experiments were performed. In initial experiment, soaked seeds were taken into the centrifuge tubes filled with 1 ml D/W. Seeds were exposed to hypergravity ranging from 500 g to 2500 g for 10 minutes. In another experiment, soaked seeds were taken into the centrifuge tubes without water or any other medium and then exposed to high g values. After exposure seeds were immediately sowed on 0.8% agar gel. Results obtained showed that exposure to high g values suppressed growth in wheat seedlings when seeds were exposed to high g values with water as a medium. Chlorophyll content also decreased with increase in g. However, no change in growth and chlorophyll content were observed when seeds were exposed without water medium up to g values as high as 2500. Thus, effects of high g value stimuli depend not only on how much centrifugal force is applied to the seeds but also depends upon how much force is experienced by the inner part of the seeds. Present observation shows that effective centrifugal force experienced by the seeds is different when applied with and without medium.

Numerical investigation on convective heat transfer of supercritical aviation kerosene in a horizontal tube under hyper gravity conditions

Objective To establish a hypergravity loading model with a high-acceleration centrifugal loading device and to investigate the effects of different hypergravity loading and icariin on osteoblast adhesion and cytoskeleton. Methods MC3T3-E1 cells were seeded in the dishes of cell culture at a density of 2×105/cm2. And the experiment was divided into 6 groups: control group (without icariin and loading); simple administration group (only icariin); 10 G loading group (only loading); 10 G administration group (with icariin and loading); 40 G loading group (only loading); 40 G administration group (with icariin and loading). The experimental loading group was loaded with MC3T3-E1 cells using a high-acceleration centrifugal loader. And continuous loading for 3 d, 30 min per d. The control group and the simple administration group were exposed to normal gravity, and the remaining conditions were not different from the experimental group. Icariin was used at a concentration of 10-7 mol/L in all administration groups, and the experiments were carried out according to the method of preventive administration. At the same time, the related molecular biological techniques such as alizarin red staining, alkaline phosphatase (ALP) activity measurement, CCK-8 cell proliferation experiment, cytoskeleton phalloidin staining, qPCR and Western Blot were used to detect the effects of icariin on osteoblasts adhesion protein integrin α5 and integrin β1 and cytoskeleton protein F-actin under hypergravity extreme mechanical environment. Results All models were successfully prepared. The alizarin red staining: The icariin could significantly promote the formation of osteoblastic calcified nodules. And the 10 G loading could also promote the mineralization of osteoblasts and increase the number of mineralized nodules, while the mineralization and the number of mineralized nodules of osteoblasts are significantly reduced in 40 G loading. ALP activity test: The OD values of simple administration group, 10 G loading group and 40 G loading group were 0.246, 0.331 and 0.163, respectively. Compared with 0.207 in the control group, the differences were statistically significant (P<0.05). The 10 G administration group and the 40 G administration group were 0.373 and 0.180, and the differences were statistically significant (P<0.05). The results of CCK-8 proliferation experiments: The OD value of simple administration group were 0.650, which was statistically significant compared with 0.551 of control group (P=0.031). The 10 G loading group and 40 G loading group were 1.193 and 0.245, and their differences with the control group were both statistically significant (P<0.05). The OD value of 10G administration group and the 40 G administration group were 1.300 and 0.310, which were significantly different from the respective loading groups (P<0.05). Phalloidin staining: 10 G loading significantly increased the number of cells, but the changes in cells morphology and skeleton were not obvious. 40 G loading significantly inhibited the increase of the number of cells, meanwhile, made the pseudopods of cells more shorter and even disappeared. 40 G loading made the seriously damage of the cytoskeleton and even cause the cells to death. Icariin had no effect on the cells morphology, but it did has a certain repair effect after the cells loading. The results of qPCR and Western Blot experiments all confirmed that the expressions of integrin α5, integrin β1 and F-actin were up-regulated after icariin treatment. 10 G loading could promote the expression of integrin α5, integrin β1 and F-actin, and 40 G loading significantly inhibited the expression of the mRNA and proteins. Conclusion Both 10 G condition and icariin can promote the development, cell adhesion and the cytoskeleton's stability of osteoblasts, while 40 G has a significant inhibitory effect. Key words: Osteoblast; Hypergravity; Cell adhesion; Cytoskeleton

Convective boiling heat transfer under microgravity and hypergravity conditions

The control of bipedal stance and the capacity to regain postural equilibrium after its deterioration in variable gravities are crucial prerequisites for manned space missions. With an emphasize on natural orthograde posture, computational techniques synthesize muscle activation patterns of high complexity to a simple synergy organization. We used nonnegative matrix factorization to identify muscle synergies during postural recovery responses in human and to examine the functional significance of such synergies for hyper-gravity (1.75 g) and hypo-gravity (0.25 g). Electromyographic data were recorded from leg, trunk and arm muscles of five human exposed to five modes of anterior and posterior support surface translations during parabolic flights including transitional g-levels of 0.25, 1 and 1.75 g. Results showed that in 1 g four synergies accounted for 99% of the automatic postural response across all muscles and perturbation directions. Each synergy in 1 g was correlated to the corresponding one in 0.25 and 1.75 g. This study therefore emphasizes the similarity of the synergy organization of postural recovery responses in Earth, hypo- and hyper-gravity conditions, indicating that the muscle synergies and segmental strategies acquired under terrestrial habits are robust and persistent across variable and acute changes in gravity levels.

Photothermal nanobubble nucleation on a plasmonic nanoparticle: A 3D lattice Boltzmann simulation

Abstract Alteration in gravitational load impacts homeorhetic response in rat dams which affects neonatal pup survival. However, the effects of hypergravity (HG) exposure on the abundance of apoptosis-associated proteins in mammary epithelial cells (MECs) have not been characterized. Therefore, we examined whether chronic exposure to HG from midpregnancy alters the abundance of proapoptotic proteins in MECs during the late pregnancy and early lactation. A group of pregnant Sprague Dawley rats were exposed to either HG (2g) or normo-gravity (1g: stationary control [SC]) from days 11 to 20 of gestation (G20). Another set of animals were investigated from day 11 of pregnancy through days 1 and 3 (P1 and P3, respectively) postpartum. Quantitative (pixels [px]/lobule) immunohistochemistry at G20 of Cleaved Caspase-3 (CC-3), Tumor Protein p53 (P53), and vitamin D receptor (VDR) revealed that all the three proteins were increased (p&lt;0.01) in HG rats compared to SC animals. At P1, the HG group had twofold higher (p&lt;0.001) expression of CC-3 relative to the SC group. Approximately, 50% (p&lt;0.001) more VDR was detected in the HG cohorts than SC at P3. These results suggest that a shift in g-load upregulates the expression of key proapoptotic proteins during the pregnancy-to-lactation transition in the rat MECs.

Heat transfer in nucleate boiling relies on the detachment and rise of the boiling bubble, in which gravity plays the dominant role. Previous studies showed that in the absence of gravity, the bubble fails to rise, causing the dryout of the heater and significantly reducing the thermal efficiency of nucleate boiling. Recently, a new boiling regime termed oscillate boiling was discovered. By localizing thermal energy as high as 50 mW into an area as small as 15 × 15μm2, a boiling bubble is formed and oscillate at high frequency while remaining pinned at the heating spot. This regime was proposed to be independent of buoyancy as its operation does not involves the detachment and rise of the boiling bubble. To test this hypothesis, we compared experimental observations of oscillate boiling in low gravity, normal gravity and hyper gravity. The results support the hypothesis and promote its potential for outer-space heat transfer application.

Transparent tubes with functions of heating and temperature measurement are badly required in the visualization investigation of two-phase flows and flow-boiling heat transfer. In order to prepare such a tube, we introduced a cost-effective and energy-efficient procedure of hypergravity assisted chemical liquid deposition (HACLD) to produce transparent and conductive silver (Ag) films on the inner surfaces of quartz tubes, typically 50 mm in length and 8 mm in inner diameter with a set-up that designed and built for this purpose. Precursors of organometallic Ag precursor solutions were prepared by dissolving silver citrate and 1,2-diaminopropane in 2-methoxyethanol with required concentration for the chemical liquid deposition process. Semitransparent and conductive Ag films formed inside the required quartz tubes under specific heating process in hypergravity. One of the films was about 47 nm in thickness, 23 ohms per square sheet resistance, and 30% optical transmittance. This attempt may pave a way for the understanding of the film forming mechanism in hypergravity, and the development of a film preparation technology of HACLD.