Salidroside promotes osteoblast proliferation and differentiation via the activation of AMPK to inhibit bone resorption of knee osteoarthritis mice.

AIM: Balance between osteoclasts and osteoblasts was important for bone development and regeneration, which attracted wide attention. To investigate whether the pro-restorative effect of salidroside (SAL) on knee osteoarthritis in mice was associated with adenosine monophosphate-activated protein kinase (AMPK). METHODS: MC3T3-E1 cells were used to perform CCK8, ALP measurement, alizarin red assay and western blot. Mouse model with knee osteoarthritis was constructed and received the treatment of SAL. Body weight, arthritis index, and inflammatory factors were recorded and measured. The paraffin sections of knee bone joints were performed by HE and immunohistochemical staining. Western blot was carried out. CCK8, EDU and flow cytometry were used to analyzed the inhibitory effect of salidroside on osteoclast. RESULTS: We found that salidroside could promote osteoblast proliferation and differentiation, and upregulate COL1A1, RUNX2 and OCN proteins and increase ALP content and phosphorylation level of AMPK. In vivo assays showed that salidroside inhibited inflammatory reaction, improved pathological condition. Salidroside reduced TRAP and NFATc1 expression, and increased the expression of ALP, COL1A1, RUNX2 and OCN proteins. p-AMPK protein was upregulated by salidroside treatment. We also performed in vitro assay, and found salidroside could inhibit proliferation of osteoclast and increase apoptosis of osteoclast. CONCLUSION: In a word, salidroside promoted osteoblast proliferation and differentiation through AMPK activation to further inhibit osteoclast bone resorption, so as to achieve the purpose of relieving knee osteoarthritis.

Circ_0008956 contributes to IL-1ß-induced osteoarthritis progression via miR-149-5p/NAMPT axis.

Circular RNAs (circRNAs) have been identified to involve in the pathophysiology of osteoarthritis (OA). Herein, this study aimed to investigate the role and mechanisms underlying circ_0008956 in the process of OA. The expression of circ_0008956 and microRNA (miR)-149-5p and Nicotinamide phosphoribosyl transferase 1 (NAMPT) was detected using quantitative real-time polymerase chain reaction and Western blot assays. Cell viability, apoptosis, cell cycle and extracellular matrix (ECM) degradation were analyzed using cell counting kit-8, flow cytometry, and Western blot assays, respectively. The binding interaction between miR-149-5p and circ_0008956 or NAMPT was confirmed using dual-luciferase reporter assay. Circ_0008956 was highly expressed in OA cartilage tissues and interleukin (IL)-1ß mediated chondrocytes. Knockdown of circ_0008956 promoted cell viability, cell cycle, suppressed cell apoptosis, and increased type II collagen and aggracan expression in IL-1ß-treated chondrocytes. MiR-149-5p was verified to be a target of circ_0008956, inhibition of miR-149-5p reversed the protective effects of circ_0008956 knockdown on IL-1ß-stimulated chondrocytes. NAMPT was a target of miR-149-5p, miR-149-5p attenuated IL-1ß-induced growth arrest and ECM degradation in chondrocytes, which was abolished by NAMPT overexpression. Importantly, circ_0008956 served as a sponge for miR-149-5p to up-regulate NAMPT expression in chondrocytes. Circ_0008956 contributed to IL-1ß-induced growth arrest and ECM degradation in chondrocytes via miR-149-5p/NAMPT axis, suggesting a new insight into the pathogenesis of OA and a promising therapeutic target for OA treatment.

Star sensor calibration with separation of intrinsic and extrinsic parameters.

The calibration method based on integrated modeling with intrinsic and extrinsic parameters is widely used for star sensors. However, the unified optimization of parameters results in the coupling between intrinsic and extrinsic parameters in this method, further influencing the calibration accuracy of the intrinsic parameters and causing certain limitations for the practical applications involving precise extrinsic parameters. A novel calibration method for star sensors with separation of intrinsic and extrinsic parameters is proposed in this paper to solve the issue. Firstly, the coupling form of intrinsic and extrinsic parameters in the integrated calibration model is analyzed, and the coupling degree is analyzed through the partial correlation coefficient (PCC). Then, on the basis of the analysis results, combined with the applications of star sensors in satellites and missiles, the extrinsic parameters coupled with the intrinsic parameters are separated individually, and the intrinsic and extrinsic parameters without coupling are optimized nonlinearly as a whole. The experimental results verify the validity of the proposed method.

Camera calibration based on two-cylinder target.

A large-size 2D target cannot be used for calibration in the application scenarios with confined spaces, neither can traditional 1D target because the need of constrained motion. To solve this problem, a camera calibration method based on two-cylinder (TC) target is proposed. The TC target is placed in the Field of View (FOV) arbitrarily and images of the target are acquired from multiple views, then the camera can be calibrated by establishing the perspective projection relationship between the TC target and its projective contours in each view. The experiments with both synthetic and real data show that the proposed method has better anti-noise ability and higher accuracy compared with small-size 2D target.

Plume Noise Suppression Algorithm for Missile-Borne Star Sensor Based on Star Point Shape and Angular Distance between Stars.

When a missile is launched, the plume generated by the propulsion system will produce a lot of fake stars in the star image, which will affect the normal work of the missile-borne star sensor. A plume noise suppression algorithm based on star point shape and angular distance between stars is proposed in this paper, which is a preprocessing algorithm for star identification. Firstly, principal component analysis is used to extract the shape features of star points. Secondly, the authenticity of star points is evaluated based on length-width ratios. Thirdly, in two consecutive frames of star images, according to the shape features of star points, the optimal matching window is determined to achieve accurate matching of the corresponding star points. Finally, the rapid elimination of fake stars is completed by the principle of invariant angular distance between true stars. Simulation experiment results show that the proposed algorithm is quite robust and fast, and the elimination ratio is high even if the number of fake stars reaches four times more than true stars. Compared with the existing star identification algorithms, when the number of fake stars is large, the advantage of the proposed algorithm is obvious. Experimentation on actual star images verifies that the proposed algorithm can meet the requirements of spacecraft even if there are a large number of fake stars in the star image.

Optimal design of an antireflection coating structure for enhancing the energy-conversion efficiency of a silicon nanostructure solar cell.

In this paper, we present our investigation of the optical and electrical characteristics of silicon solar cells using silicon nanowire, silicon nanocone, silicon nanopillar, and silicon nanopillar/silicon nitride structures, which were obtained by the Ag-assisted electroless etching method and ICP etching with extreme ultraviolet lithography. We introduced the formation mechanism for four kinds of solar cells. We simulated the absorption of four structures for different parameters. Furthermore, we also performed current density-voltage (J-V) characterization of the samples with silicon nitride, which exhibited an improvement of the power conversion efficiency (PCE) in contrast to the samples without silicon nitride. It was found that the properties of trapping light for silicon nitride had a prominent impact on the improvement of the PCE in the silicon nanopillar solar cells.

Micro digital sun sensor with linear detector.

In this paper, the design of a novel micro digital sun sensor is described. It relies on V-shaped slit and linear array CCD to measure sun-ray angle against two axes. A highly integrated microprogram control unit) is used to make a very simple and compact system. V-shaped slit can simplify algorithm and achieve a wider field of view. Error compensation and accurate calibration are employed to improve accuracy. Adaptive threshold and adjustable expose time further improve reliability. Experiments and flight validation show that the FOV (Field of View) of the sun sensor is ±65° × ± 65° and the accuracy is 0.1° in the whole FOV. It can work reliably at an update rate of 25 Hz, while the consumption is only 200 mW. This sun sensor is proved to have a good prospect in micro/nanosatellites.

Error modeling and calibration for encoded sun sensors.

Error factors in the encoded sun sensor (ESS) are analyzed and simulated. Based on the analysis results, an ESS error compensation model containing structural errors and fine-code algorithm errors is established, and the corresponding calibration method for model parameters is proposed. As external parameters, installation deviation between ESS and calibration equipment are introduced to the ESS calibration model, so that the model parameters can be calibrated accurately. The experimental results show that within plus/minus 60 degree of incident angle, the ESS measurement accuracy after compensation is three times higher on average than that before compensation.