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  • Articles  (1,602)
  • Springer  (1,602)
  • Institute of Electrical and Electronics Engineers (IEEE)
  • National Academy of Sciences
  • Microgravity Science and Technology  (396)
  • Microgravity Science and Technology. 2001; 13(1): 14-19. Published 2001 Mar 01. doi: 10.1007/bf02873326.  (1)
  • Microgravity Science and Technology. 2001; 13(1): 20-23. Published 2001 Mar 01. doi: 10.1007/bf02873327.  (1)
  • Microgravity Science and Technology. 2001; 13(1): 24-28. Published 2001 Mar 01. doi: 10.1007/bf02873328.  (1)
  • Microgravity Science and Technology. 2001; 13(1): 29-34. Published 2001 Mar 01. doi: 10.1007/bf02873329.  (1)
  • Microgravity Science and Technology. 2001; 13(1): 3-6. Published 2001 Mar 01. doi: 10.1007/bf02873324.  (1)
  • Microgravity Science and Technology. 2001; 13(1): 35-38. Published 2001 Mar 01. doi: 10.1007/bf02873330.  (1)
  • Microgravity Science and Technology. 2001; 13(1): 8-12. Published 2001 Mar 01. doi: 10.1007/bf02873325.  (1)
  • Microgravity Science and Technology. 2002; 13(2): 12-15. Published 2002 Jun 01. doi: 10.1007/bf02872066.  (1)
  • Microgravity Science and Technology. 2002; 13(2): 16-21. Published 2002 Jun 01. doi: 10.1007/bf02872067.  (1)
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  • Natural Sciences in General  (1,602)
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  • Articles  (1,602)
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  • Springer  (1,602)
  • Institute of Electrical and Electronics Engineers (IEEE)
  • National Academy of Sciences
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  • 1
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    Machine Learning for 3D Particle Tracking in Granular Gases (2020)
    Springer
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    Publication Date: 2020-07-18
    Description: Dilute ensembles of granular matter (so-called granular gases) are nonlinear systems which exhibit fascinating dynamical behavior far from equilibrium, including non-Gaussian distributions of velocities and rotational velocities, clustering, and violation of energy equipartition. In order to understand their dynamic properties, microgravity experiments were performed in suborbital flights and drop tower experiments. Up to now, the experimental images were evaluated mostly manually. Here, we introduce an approach for automatic 3D tracking of positions and orientations of rod-like particles in a dilute ensemble, based on two-view video data analysis. A two-dimensional (2D) localization of particles is performed using a Mask R-CNN neural network trained on a custom data set. The problem of 3D matching of the particles is solved by minimization of the total reprojection error, and finally, particle trajectories are tracked so that ensemble statistics are extracted. Depending on the required accuracy, the software can work fully self-sustainingly or serve as a base for subsequent manual corrections. The approach can be extended to other 3D and 2D particle tracking problems.
    Print ISSN: 0938-0108
    Electronic ISSN: 1875-0494
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Technology
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  • 2
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    Microtubules and Vimentin Fiber Stability during Parabolic Flights (2020)
    Springer
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    Publication Date: 2020-07-19
    Description: Adequate mechanical stimulation is essential for cellular health and tissue maintenance, including articular cartilage, which lines the articulating bones in joints. Chondrocytes, which are the sole cells found in articular cartilage, are responsible for matrix synthesis, maintenance and degradation. It is generally believed that chondrocytes require mechanical stimuli through daily physical activity for adequate cartilage homeostasis. However, to date, the molecular mechanisms of cellular force sensing (mechanotransduction) are not fully understood. Among other mechanisms, the cytoskeleton is thought to play a key role. Despite that gravity is a very small force at the cellular level, cytoskeletal adaptations have been observed under altered gravity conditions of a parabolic flight in multiple cell types. In this study, we developed a novel hardware which allowed to chemically fix primary bovine chondrocytes at 7 time points over the course of a 31-parabola flight. The samples were subsequently stained for the microtubules and vimentin network and microscopic images were acquired. The images showed a large heterogeneity among the cells in morphology as well as in the structure of both networks. In all, no changes or adaptions in cytoskeleton structure could be detected over the course of the parabolic flight.
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Technology
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  • 3
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    Design, Simulation and Test of Thermal Control System of Centrifuge for Space Utilization (2020)
    Springer
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    Publication Date: 2020-07-16
    Print ISSN: 0938-0108
    Electronic ISSN: 1875-0494
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Technology
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  • 4
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    Small RNA Deep Sequencing and the Effects of microRNA408 on Root Gravitropic Bending in Arabidopsis (2015)
    Springer
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    Publication Date: 2015-08-21
    Description: MicroRNA (miRNA) is a non-coding small RNA composed of 20 to 24 nucleotides that influences plant root development. This study analyzed the miRNA expression in Arabidopsis root tip cells using Illumina sequencing and real-time PCR before (sample 0) and 15 min after (sample 15) a 3-D clinostat rotational treatment was administered. After stimulation was performed, the expression levels of seven miRNA genes, including Arabidopsis miR160, miR161, miR394, miR402, miR403, miR408, and miR823, were significantly upregulated. Illumina sequencing results also revealed two novel miRNAsthat have not been previously reported, The target genes of these miRNAs included pentatricopeptide repeat-containing protein and diadenosine tetraphosphate hydrolase. An overexpression vector of Arabidopsis miR408 was constructed and transferred to Arabidopsis plant. The roots of plants over expressing miR408 exhibited a slower reorientation upon gravistimulation in comparison with those of wild-type. This result indicate that miR408 could play a role in root gravitropic response.
    Print ISSN: 0938-0108
    Electronic ISSN: 1875-0494
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Technology
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  • 5
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    Dynamical and Microrheological Analysis of Amyloplasts in the Plant Root Gravity-Sensing Cells (2015)
    Springer
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    Publication Date: 2015-08-04
    Description: Gravitropism in plants is one of the most controversial issues. In the most wildly accepted starch-statolith hypothesis the sedimentation movement of amyloplasts in the gravisensing columella cells primarily triggers the asymmetric distribution of auxin which leads to the differential growth of the plant root. It has been gradually recognized that the inhomogeneous structures in statocytes arising from intracellular components such as cytoskeletons significantly affect the complex movements of amyloplasts and the final gravimorphogenesis. In this letter, we implement a diffusive dynamics measurement and inplanta microrheological analysis of amyloplasts in the wild-type plants and actin cytoskeleton mutants for the first time. We found that the intracellular environment of columella cells exhibits the spatial heterogeneity and the cage-confinement on amyloplasts which is the typically characteristics in colloidal suspensions. By comparing the distinct diffusive dynamics of amyloplasts in different types of plants with the behaviors of colloidal systems in different states, we quantitatively characterized the influence of the actin organization dominated intracellular envoronments on the amyloplast movements. Furthermore, the cage-confinement strength was measured by calculating the spatial fluctuation of local apparent viscosity within the columella cells. Finally, a linear association between the initial mechanical stimulation in the columella cells the subsequent intercellular signal transduction and the final gravity response was observed and a possible gravity sensing mechanism was suggested. It suggests the existence of a potential gravity-sensing mechanism that dictates a linear frustration effect of the actin cytoskeleton on the conversion of the mechanical stimulation of amyloplasts into gravitropic signals.
    Print ISSN: 0938-0108
    Electronic ISSN: 1875-0494
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Technology
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  • 6
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    Simulating Parabolic Flight like g -Profiles on Ground - A Combination of Centrifuge and Clinostat (2015)
    Springer
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    Publication Date: 2015-09-25
    Description: Clinostats and centrifuges are widely used to create simulated microgravity or hypergravity, respectively, in order to study the impact of gravity on biosystems. Here, we used a clinostat and a centrifuge in alternating modes of operation in order to create a simulated parabolic flight like g -profile. To our knowledge, it is the first time that both devices were run in connection. In order to test the method, we investigated the production of reactive oxygen species of immune cells (macrophages) during oxidative burst in an on-line kinetic approach, which has been extensively studied under real (parabolic flight) and simulated microgravity (clinostat) as well as under hypergravity conditions (centrifuge). Our results indicate that clinostat and centrifuge can be operated in an alternating way to simulate the repetitive changes of gravity during parabolic flight. Although the switch from one gravity level to the other could not be carried out as quickly as it takes place during actual parabolic flight due to technical and operational reasons, it can be concluded that running experiments in a clinostat aboard a centrifuge on ground are suitable for studying gravity-related phenomena.
    Print ISSN: 0938-0108
    Electronic ISSN: 1875-0494
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Technology
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  • 7
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    Evaluation of Simulated Microgravity Environments Induced by Diamagnetic Levitation of Plant Cell Suspension Cultures (2015)
    Springer
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    Publication Date: 2015-11-21
    Description: Ground-Based Facilities (GBF) are essetial tools to understand the physical and biological effects of the absence of gravity and they are necessary to prepare and complement space experiments. It has been shown previously that a real microgravity environment induces the dissociation of cell proliferation from cell growth in seedling root meristems, which are limited populations of proliferating cells. Plant cell cultures are large and homogeneous populations of proliferating cells, so that they are a convenient model to study the effects of altered gravity on cellular mechanisms regulating cell proliferation and associated cell growth. Cell suspension cultures of the Arabidopsis thaliana cell line MM2d were exposed to four altered gravity and magnetic field environments in a magnetic levitation facility for 3 hours, including two simulated microgravity and Mars-like gravity levels obtained with different magnetic field intensities. Samples were processed either by quick freezing, to be used in flow cytometry for cell cycle studies, or by chemical fixation for microscopy techniques to measure parameters of the nucleolus. Although the trend of the results was the same as those obtained in real microgravity on meristems (increased cell proliferation and decreased cell growth), we provide a technical discussion in the context of validation of proper conditions to achieve true cell levitation inside a levitating droplet. We conclude that the use of magnetic levitation as a simulated microgravity GBF for cell suspension cultures is not recommended.
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Technology
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  • 8
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    Hypergravity Facilities in the ESA Ground-Based Facility Program – Current Research Activities and Future Tasks (2015)
    Springer
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    Publication Date: 2015-10-25
    Description: Research on Artificial Gravity (AG) created by linear acceleration or centrifugation has a long history and could significantly contribute to realize long-term human spaceflight in the future. Employing centrifuges plays a prominent role in human physiology and gravitational biology. This article gives a short review about the background of Artificial Gravity with respect to hypergravity (including partial gravity) and provides information about actual ESA ground-based facilities for research on a variety of biosystems such as cells, plants, animals or, particularly, humans.
    Print ISSN: 0938-0108
    Electronic ISSN: 1875-0494
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Technology
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  • 9
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    Changes in Plastid and Mitochondria Protein Expression in Arabidopsis Thaliana Callus on Board Chinese Spacecraft SZ-8 (2015)
    Springer
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    Publication Date: 2015-06-02
    Description: Microgravity represents an adverse abiotic environment, which causes rearrangements in cellular organelles and changes in the energy metabolism of cells. Plastids and mitochondria are two subcellular energy organelles that are responsible for major metabolic processes, including photosynthesis, oxidative phosphorylation, ß -oxidation, and the tricarboxylic acid cycle. In our previous study performed on board the Chinese spacecraft SZ-8, we evaluated the global changes exerted by microgravity on the proteome of Arabidopsis thaliana cell cultures by comparing the microgravity-exposed samples with the controls either under 1 g centrifugation in space or 1 g ground conditions. Here, we report additional data from this space experiment that highlights the plastid and mitochondria proteins that responded to space flight conditions. We observed that 43 plastidial proteins and 50 mitochondrial proteins changed their abundances under microgravity in space. The major changes in both plastids and mitochondria involved proteins that functions in a suite of redox antioxidant and metabolic pathways. These results suggested that these antioxidant and metabolic changes in plastids and mitochondria could be important components of the adaptive strategy in plants subjected to microgravity in space.
    Print ISSN: 0938-0108
    Electronic ISSN: 1875-0494
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Technology
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  • 10
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    Drop Tower Experiment to Study the Capillary Flow in Symmetrical and Asymmetrical Channels: Experimental Set-up and Preliminary Results (2016)
    Springer
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    Publication Date: 2016-08-03
    Description: Owing to the development of the space exploration activities, the in-orbit management of fluids such as the transportation of propellant liquid in microgravity becomes the important direction of microgravity fluid research, and one of main problems is the stability behaviors of free surface flow in capillary channel of PMD. In the present study, an experiment set-up of the fluid transport with two different capillary channels has been developed on the Beijing Drop Tower platform. Both symmetrical and asymmetrical flow channels, with the same cross-sectional areas and lengths and different cross-sectional geometries were used and HFE-7500 is chosen as test liquid. 10 times of the drop-down experiments were performed for investigation of the capillary flow characters in different volumetric flow rates, and the three main patterns of capillary flows: subcritical flow, critical flow and supercritical flow were found in experiments, these patterns are distinguished by the movement of the point of lowest surface over time. Meanwhile, the critical flow rates at which free surface becomes instable observed in our experiments are (1) 2.7 ±0.2ml/s for the critical flow rate of asymmetrical channel; and (2) 2.2 ±0.2ml/s for symmetrical channel flow, respectively.
    Print ISSN: 0938-0108
    Electronic ISSN: 1875-0494
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Natural Sciences in General , Technology
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