Search

Abstract Bone loss caused by long-duration spaceflight seriously affects the skeletal health of astronauts. There are many shortcomings in currently available treatments for weightlessness-induced bone loss. The aim of this study was to evaluate the preventive effect of Angelica dahuricae Radix (AR) on simulated microgravity-induced bone loss. Here, we established a hind limb unloading (HLU) mouse model and treated HLU mice with AR (2 g/kg) for 4 weeks. Results indicated that AR significantly inhibited simulated microgravity-induced bone loss. In addition, the components in AR were analyzed using UPLC-MS/MS; results showed that a total of 224 compounds were detected in AR, which mainly contained 7 classes of components. Moreover, the network pharmacological predictions suggested that active ingredients of AR might act on PTGS2 to prevent bone loss. These results elucidate the efficacy of AR in preventing microgravity-induced bone loss and its potential for use in protecting the bone health of astronauts.

Abstract Bone loss induced by microgravity exposure seriously endangers the astronauts’ health, but its countermeasures still have certain limitations. The study aims to find potential protective drugs for the prevention of the microgravity-induced bone loss. Here, we utilized the network pharmacology approach to discover a natural compound calycosin by constructing the compound-target interaction network and analyzing the topological characteristics of the network. Furthermore, the hind limb unloading (HLU) rats’ model was conducted to investigate the potential effects of calycosin in the prevention of bone loss induced by microgravity. The results indicated that calycosin treatment group significantly increased the bone mineral density (BMD), ameliorated the microstructure of femoral trabecular bone, the thickness of cortical bone and the biomechanical properties of the bone in rats, compared that in the HLU group. The analysis of bone turnover markers in serum showed that both the bone formation markers and bone resorption markers decreased after calycosin treatment. Moreover, we found that bone remodeling-related cytokines in serum including IFN-γ, IL-6, IL-8, IL-12, IL-4, IL-10 and TNF-α were partly recovered after calycosin treatment compared with HLU group. In conclusion, calycosin partly recovered hind limb unloading-induced bone loss through the regulation of bone remodeling. These results provided the evidence that calycosin might play an important role in maintaining bone mass in HLU rats, indicating its promising application in the treatment of bone loss induced by microgravity.

Covariance analysis describing function technique is a conventional method to solve the performance analysis of the nonlinear missile guidance system. Aiming at the faultiness of covariance analysis describing function technique and its improved method, this paper proposes a new method to solve the mean and covariance transfer issue by using the high-degree spherical-radial cubature rule. In terms of simulation models, the nonlinear missile guidance system contains the saturation link to limit the lateral acceleration command and the initial heading error is introduced. In addition, the zero-mean target evasive maneuver with exponentially-decaying autocorrelation function is chosen as the input of the missile guidance system. Furthermore, compared with the existing methods, the proposed method has higher computational efficiency, accuracy and better applicability in high-dimensional nonlinear systems by theoretical derivation and simulation results from the mean and covariance values of relative lateral separation. Finally, the presented analysis method can be used as a general method for the design and statistical analysis of multidimensional nonlinear systems.

Aimed at the poor performance of guidance algorithms designed based on a linearized model in active defense under large leading angle deviation, both-way and one-way cooperative sliding mode guidance algorithms based on the smooth nonsingular terminal sliding mode for the defense missile are proposed. The relative kinematics and linearized models of the target, the active defense missile, and the attacking missile are established. In the design process, two smooth nonsingular terminal sliding mode surfaces are constructed based on zero-effort miss distance and zero-effort velocity, as well as their integral values. A tracking differentiator is introduced for excessive initial command deviation to meet the overload constraints of the active missile and the target. The sensitivity of guidance law to the estimated time-to-go error is reduced, and the target is allowed to perform an independent evasive maneuver. The effectiveness of the proposed guidance strategy is verified by numerical simulation and compared to the existing guidance strategies, the high accuracy, anti-chattering, and strong robustness of the proposed guidance algorithm are verified.