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Introduction: High + Gz loads, the gravitational forces experienced by the body in hypergravity environments, can lead to bone loss in pilots and astronauts, posing significant health risks. Materials and methods: To explore the effect of treadmill exercise on bone tissue recovery, a study was conducted on 72 male Wistar rats. These rats were subjected to four weeks of varying levels of periodic high + Gz loads (1G, 8G, 20G) experiments, and were subsequently divided into the treadmill group and the control group. The treadmill group underwent a continuous two-week treadmill experiment, while the control group rested during this period. The mechanical properties, microstructure, and molecular markers of their tibial bone tissue were measured using three-point bending, micro-CT, and PCR. Results: The results showed that treadmill exercise improved the elastic modulus, ultimate deflection, and ultimate load of rat bone tissue. It also increased the number, density, and volume fraction of bone trabeculae, and decreased their separation. Moreover, treadmill exercise enhanced osteogenesis and inhibited osteoclastogenesis. Conclusion: This study demonstrates that treadmill exercise can promote the recovery of bone tissue in rats subjected to high + Gz loads, providing a potential countermeasure for bone loss in pilots and astronauts. [ABSTRACT FROM AUTHOR]

• A high accuracy deformation measurement method for semi-continuous materials is proposed. • The deformation field of 3D printed scaffolds is accurately measured. • The first visualization of cell differentiation on scaffolds was achieved by experimental measurements. • The effects of loading in vitro and water content on cell differentiation were investigated. • This work corroborates that in vitro loading culture and modulation of scaffold pore structure can be exploited to design scaffolds with regions that guide specific tissue development. Three-dimensional (3D) mechanical microenvironments, such as 3D strain fields in tissue engineering scaffolds have a crucial impact on the interactions between scaffold architecture, mechanical stimuli, and tissue differentiation. However, the discontinuity induced by the pores poses a challenge to the measurement of the 3D strains of the scaffolds. Herein, we present a tissue engineering scaffold optical coherence elastography (TES-OCE) method to visualize the full-field 3D strain fields of the tissue engineering scaffolds when cells are cultured on them and to explore the relationship between mechanical stimulation and cell differentiation. A semi-continuous digital volume correlation (SC-DVC) method based on a material component identification algorithm was proposed to automatically extract the scaffold architecture information and obtain the 3D strain fields with high accuracy. The non-uniform deformation field of a 3D printed tissue engineering scaffold with various water contents under loading in vitro was measured by the TES-OCE method, based on the tissue shear strain field obtained above, the area of cell differentiation phenotype on tissue engineering scaffolds was accurately predicted. Experimental results show that the loads and water absorption of the scaffold significantly affects the 3D tissue shear strain field in the tissue engineering scaffold. Thus, the cell differentiation fate can be modulated by loading culture and scaffold pore structure. The TES-OCE provides a new experimental method to delineate the interrelationship between tissue engineering scaffolds, the mechanical microenvironment, and cell proliferation and differentiation. It may be further developed as an effective tool to guide the design and development of superior tissue engineering scaffolds. [ABSTRACT FROM AUTHOR]

Abstract Chromium (Cr) is a well-known toxic metal, but studies on Cr toxicity to soil-dwelling springtails are fairly limited, and did not consider the effects of various soil properties and long aging time. To address this, the chronic toxicity of Cr(VI) to survival and reproduction of model organism— Folsomia candida were evaluated in the laboratory studies. The results showed that compared to the soils aged only for 2 and 21 d, the concentrations inhibiting 50% reproduction (EC 50) significantly increased by 2.8–5.2 fold and 1.7–2.6 fold, the concentrations causing 50% mortality (LC 50) were higher than the highest test concentration in four soils aged for 150 d. Furthermore, the aging effects correlated significantly with soil amorphous Fe oxides. The EC 50 values of Cr significantly differed in ten soils aged for 150 d, ranging from 27 to 512 mg kg−1, which were associated with the variations in reduction and sorption capacity in different soils. Regression analysis indicated that soil clay was the most important single factor predicting soil Cr toxicity to reproduction, and the inclusion of cation exchange capacity in the clay regression could best explain the toxicity variance (87.2%). Additionally, soil pH, organic matter and amorphous Fe oxides could also well explain the toxicity variance (>55%). Highlights • Prediction models of Cr toxicity to springtail as a function of soil properties were developed. • Soil clay was the most important single factor predicting soil Cr toxicity to springtail. • Toxicity of Cr to springtail decreased significantly after aging for 150 d. • Decreased toxicity with increasing aging in Cr(VI)-treated soil closely related to Cr(VI) reduction. [ABSTRACT FROM AUTHOR]

[Display omitted] The tissue engineering is a promising method for cartilage regeneration studies. The rough in vivo initial repair environment of articular cartilage is a challenge for the development of cartilage tissue engineering. Hereon, in this study, a silk fibroin/collagen type II scaffold was designed. The optimal mechanical environment for chondrocyte/scaffold complex in vitro maturation culture was determined and in vitro cultured mature artificial cartilage was evaluated for in vivo defect repair. Our research shows that the silk fibroin/collagen type II scaffold has good performance and can meet the special requirements of cartilage repair. 10 % compressive strain is the optimal compressive loading in vitro. Under optimal compression loading in vitro , chondrocytes can proliferate and grow rapidly on the scaffold to achieve better "maturation". The in vitro cultured chondrocyte/scaffold complex effectively improves the cartilage repair effect after implantation. The compressive elastic modulus of the new tissue reached 0.682 ± 0.010 MPa after 12 weeks of repair (0.714 ± 0.011 MPa for the surrounding host cartilage). Therefore, this study not only enhance the effect of cartilage repair but also provides a promising strategy for mechanical stimulation to promote functional in situ regeneration of articular cartilage. [ABSTRACT FROM AUTHOR]

To date, numerous studies have focused on the toxicity of antimony (Sb) to soil-dwelling organisms at the individual level. However, little is known about Sb-caused molecular level toxicity. Here, an integrated transcriptomics and metabolomics approach was used to better reveal toxicity of Sb(V) to springtails Folsomia candida considering environmentally relevant speciation of Sb. No significant effects of Sb(V) on survival, reproduction and growth of springtails were observed using the ISO standard test. Transcriptomics analysis identified 1015 and 3367 differentially expressed genes (DEGs) after 2 and 7 d of exposure, indicating an increasing transcriptomal changes with time. Significantly enriched top GO (Gene Ontology) terms (chitin metabolic process, chitin binding and extracellular region) were shared between the two time exposure groups. However, no enriched KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway was shared, with fatty acid metabolism and apoptosis-fly being the most significant pathway, respectively. Metabolomics analysis identified 155 differential changed metabolites (DCMs) in springtails after 7 d of exposure. Antifolate resistance was the most significantly enriched pathway, in which dihydrofolic acid was up-regulated and three purine nucleotides (adenosine 5′-monophosphate, inosine 5′-monophosphate, guanosine 5′-monophosphate) were down-regulated. This indicated obvious repression of DNA replication, which was also observed by transcriptomics. Additionally, metabolites level related to chitin, oxidative stress, and protein metabolism significantly changed, and these metabolites could also support and confirm main transcriptomic results. Thus, the combination of multiomics facilitated better understanding of the molecular level of toxicity of Sb(V) in Collembola. Unlabelled Image • Molecular level toxicity of Sb(V) to soil invertebrates was reported. • Prolonged exposure significantly increased Sb(V)-caused transcriptomal changes. • Sb(V) stress significantly influenced chitin- and DNA replication-related processes. • Combination of multiomics obtained better mechanistic understanding of Sb(V) toxicity. [ABSTRACT FROM AUTHOR]

The most existing studies on the toxicity of antimony (Sb) were performed in limited types of soil and after short aging time. Effects of soil properties and long aging time on chronic toxicity of Sb(III) and Sb(V) to model organism Folsomia candida were studied in the laboratory studies. The results showed that after the Sb(V)-treated soils were aged for 365 d, the Sb exhibited no toxicity to survival and reproduction even at the nominal highest concentration of 12,800 mg kg−1 in ten types of soils with distinct differences in soil properties. In the Sb(III)-treated ten soils aged only for 30 d, the concentrations causing 50% mortality (LC 50) and concentrations inhibiting 50% reproduction (EC 50) were 1288–3219 mg kg−1 and 683–1829 mg kg−1, respectively. The LC 50 were higher than the highest test concentration and the EC 50 significantly increased by 2.24–6.16 fold after the Sb(III)-treated soils were aged for 150 d, and soil pH was the most important single factor explaining the variance in aging effects. After the aging time was 365 d, similar with Sb(V)-treated soils, no toxicity were observed in the most Sb(III)-treated soils, indicating the increasing aging effects with aging time. Regression analysis indicated that the OM and pH were the most important single factor predicting Sb toxicity to reproduction in Sb(III)-treated soils aged for 30 and 150 d, respectively. • Prediction models of Sb toxicity in Sb(III)-treated soil were developed basing soil properties. • pH and OM could well predicted Sb toxicity in Sb(III)-treated soil. • Sb(III) and Sb(V) exhibited no toxicity after aged for 365 d in the most soils. • pH was the most important factor controlling aging effects on Sb toxicity in Sb(III)-treated soil. [ABSTRACT FROM AUTHOR]

• A new optical coherence elastography technique was developed based on harmonic mechanical excitation and surface wave spectroscopy (SWS). • The OCT B-mode phase analysis mechanism proposed, enables the actual surface wave velocity calculation from the waveform observed by OCT imaging. • The SWS model and the total variational regularization algorithm are proposed to solve the depth profile of the effective surface wave velocity, which is the key for accurate calculation of the elastic modulus of different layers. Diseases often initiate from a certain layer of the biological tissue, thus simultaneous measurement of the elastic modulus of each layer is important for early diagnosis and treatment of various diseases. A surface wave spectroscopy (SWS) optical coherence elastography (OCE) technique based on harmonic wave excitation was proposed. An actuator consisting of a piezoelectric stack with a pin was designed to generate harmonic surface waves. A B-mode OCT data acquisition and phase analysis method was proposed to image the wave forms, and calculate the surface wave velocity. By exciting the sample with different frequencies, the surface wave dispersion curves were obtained. A total variation (TV) regularization iterative algorithm was proposed to obtain the elastic modulus distribution along the depth. Effectiveness of the proposed method was evaluated by both finite element simulation and experimental measurement of a bi-layer phantom. The mechanically driven harmonic wave actuation based OCE method is simple and cost-effective in experimental setup. Based on B-mode OCT scans, data analysis can be very fast, which is possible to realize real-time elastography imaging. This study provides an effective method for biomechanical properties study of layered tissue. [ABSTRACT FROM AUTHOR]