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• An efficient formulation for rigid-flexible coupling dynamics is derived for LWPM. • The ECDM is developed by integrating the RFCDM with the dynamics model of PMSM. • Two reduced-order subsystems are decoupled using singular perturbation theory. • A hybrid control is proposed for trajectory tracking and vibration suppression. • The superiority of hybrid control is illustrated by two simulation experiments. In the scenarios of high-speed operation, the bad elastic vibrations of lightweight manipulators readily arise, thus affect the overall motion of system even induce motion instability, which is a critical issue needing to be tackled appropriately. This paper concentrates on the efficient dynamic modeling and tracking/vibration integrated control for a lightweight parallel manipulator (LWPM) including servo motor dynamics. Firstly, a systematic methodology is proposed to establish the rigid-flexible coupling dynamics model (RFDM) of mechanical system possessing a modular feature, which can reduce the modeling effort. To alleviate computational burden, the RFDM is elaborately reduced to a concise model characterized by fewer generalized coordinates of system. Further, by integrating the simplified RFDM with the dynamics model of permanent magnet synchronous motor (PMSM), the electromechanical coupling dynamics model (ECDM) of system is formulated. On this basis, the ECDM is decoupled into two reduced-order subsystems by virtue of singular perturbation theory, and following that, a novel hybrid control strategy is proposed, in which a kind of task space-based proportional-integral robust sliding mode controller is designed for the slow subsystem while an quadratic optimal controller is designed for the fast subsystem. Ultimately, two simulation experiments are implemented to comprehensively investigate the dynamic performance of the presented hybrid control in comparison with the traditional joint-based PD feedback control. The results substantiate that both the excellent trajectory tracking precision of end-effector and vibration suppression can be achieved efficiently by the hybrid control, which lays a sound foundation for the application of the proposed approach in practice. [ABSTRACT FROM AUTHOR]

Combining the digital speckle correlation method (DSCM) with the finite element model updating (FEMU) method, a new inversion method of non-uniform distribution of rock material parameters is proposed to study the characteristics of non-uniform distribution of rock material parameters and its evolution with the loading process. The non-uniform displacement field of the specimen during experimental loading is calculated based on DSCM. Based on FEMU, the experimental loading process is simulated in finite element software ABAQUS. Under the initial conditions, different material parameters (elastic modulus and Poisson’s ratio) are given for each element according to Weibull distribution to calculate the non-uniform displacement field. The objective function is constructed by the difference between the experimental displacement field and the finite element simulation displacement field. The objective function is optimized and iterated by the genetic algorithm (GA) and the particle swarm optimization (PSO) algorithm to calculate the elastic modulus and Poisson’s ratio of the experimental specimen. The inversion method for non-uniform distribution of rock materials is applied to the uniaxial compression experiment of sandstone, and the non-uniform distribution of elastic modulus and Poisson’s ratio under different loading states is obtained. The inversion method for non-uniform distribution of rock material parameters proposed in this paper provides a basis for complex experiments or structural system parameter inversion. [ABSTRACT FROM AUTHOR]

Topology and performance are the two main topics dealt in the development of robotic mechanisms. However, it is still a challenge to connect them by integrating the modeling and design process of both parts in a unified frame. As the properties associated with topology and performance, finite motion and instantaneous motion of the robot play key roles in the procedure. On the purpose of providing a fundamental preparation for integrated modeling and design, this paper carries out a review on the existing unified mathematic frameworks for motion description and computation, involving matrix Lie group and Lie algebra, dual quaternion and pure dual quaternion, finite screw and instantaneous screw. Besides the application in robotics, the review of the work from these mathematicians concentrates on the description, composition and intersection operations of the finite and instantaneous motions, especially on the exponential-differential maps which connect the two sides. Furthermore, an in-depth discussion is worked out by investigating the algebraical relationship among these methods and their further progress in integrated robotic development. The presented review offers insightful investigation to the motion description and computation, and therefore would help designers to choose appropriate mathematical tool in the integrated design and modeling and design of mechanisms and robots. [ABSTRACT FROM AUTHOR]

Background: The objective of this systematic review was to explore the association between private health insurance and health care utilization.Methods: We searched the MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) electronic databases for relevant articles since 2010. Studies were eligible if they described original empirical research on the utilization of public health care by individuals with private health insurance, compared with individuals without private insurance. A pooled measure of association between insurance status with health care utilization was assessed through meta-analysis.Results: Twenty-six articles were included in the final analysis. We found that patients with private insurance did not use more public health care than people without private insurance (P < 0.05). According to the subgroup analysis, people with private insurance were more likely to be hospitalized than people with no insurance (OR 1.67; 95% CI, 1.18 to 2.36).Conclusions: People with private insurance did not increase their use of health care (outpatient services), compared to those without private insurance. Private health insurance coverage may ease the financial burden on patients and on the public health insurance system. [ABSTRACT FROM AUTHOR]

The crucial procedure of mobility and singularity identification of parallel mechanisms is widely recognized as how to determine their motions (constraints) concisely and visually. In this paper, we propose a geometric algebra (GA) based approach to determine the motions/constraints, mobility and singularity of parallel mechanisms mainly utilizing the geometric and algebraic relations. Firstly, the motions, constraints and their relations are represented by conformal geometric algebra (CGA) formulas in a concise form by employing the characterized geometric elements with G 4 , 1 . Secondly, the mobility of parallel mechanism, including its number and property and the axes of motions, not only at origin configuration but also in the prescribed workspace, is obtained by the procedure proposed in this paper. Thirdly, the singularity of parallel mechanism is identified by the two indices proposed in this paper with shuffle and outer products. Finally, a typical example is given to illustrate the motions/constraints, mobility and singularity analysis. This approach is beneficial to kinematic analysis and optimal design of parallel mechanisms, especially for which would be carried out in automatic and visual manner using computer programming languages. [ABSTRACT FROM AUTHOR]

Taking a horizontally-mounted 3-RPS parallel kinematic machine (PKM) as an example, this paper investigates passive and active gravity compensation strategies for improving PKM precision. Herein, R, P and S denote revolute, actuated prismatic and spherical joint, respectively. Based on inverse position kinematic and force analysis, passive gravity compensation is firstly implemented by three extension springs. Geometric parameters of these springs are optimized by minimizing potential energy fluctuation within a prescribed workspace. Then deformation caused by gravity is adopted to evaluate compensation strategies. The deviations of an end reference point demonstrate that passive gravity compensation is capable of substantially balancing gravity. In order to further eliminate the effect of gravity, active gravity compensation is proposed to adjust spring displacements by several one degree-of-freedom (DoF) translational mechanisms. Deformation of the 3-RPS PKM is directly regarded as the objective function for determining the active translations. Overall, both passive and active gravity compensations are able to improve mechanism precision due to the partial and complete gravity balancing capability, respectively, which makes the 3-RPS PKM suitable for the application of rough and fine machining. [ABSTRACT FROM AUTHOR]

Driven by the requirements of inter-satellite link antenna for tracking mechanism with two degree-of-freedom (DoF), this paper proposes a 2-DoF over-constrained rotational parallel mechanism (RPM) with an articulated traveling platform and formulates its stiffness model considering gravitational effects. The stiffness modeling is implemented by three steps: 1) Considering the over-constrained property and gravitational effects, twist/wrench mapping models of two R (RU) 2 limbs connecting the fixed base and the articulated traveling platform are obtained based upon screw theory. 2) Employing deformation superposition principle, the compliance models of two R (RU) 2 limbs in their joint spaces are formulated, of which component compliance is described by n -DoF ( n ≤ 6) virtual springs; and 3) by applying deformation compatibility conditions and twist/wrench mapping models into the virtual work equations, the stiffness model of the 2-DoF over-constrained RPM considering gravitational effects is derived. From component, limbs to mechanism, the stiffness modeling process demonstrates their relations with clear physical meaning and unifies performances including kinematic, stiffness, accuracy and dynamics. This approach is verified by commercial FEA software. Finally the stiffness distribution and gravitational effects within prescribed workspace are discussed. [ABSTRACT FROM AUTHOR]

A pre folded energy absorbing device, which is the key device of energy absorption anti impact for roadway support, is tested by quasi-static compression and simulated. The energy absorbing device is divided into zones, and the influence of the area on the load displacement curve of the energy absorbing device is studied according to the area. It is found that the error of numerical simulation is within 5%, indicating that the finite element modeling procedure is appropriate for the problem analyzed here. The device crushes following the pre folded origami pattern in a stable progressive. The device was divided into four areas: the upper and lower opening region of the concave surface four corner parts; the other areas of opening regions; the middle fold edge; the surrounding four sides edge. Each area has effect on the first drop stage and the second rise stage of the load displacement curve. The middle fold edge area has an effect on the peak load value of load displacement curve. Four indicators of peak load, average load, load efficiency, and specific energy absorption were generated from the results of numerical simulation. The strength enhancement of corner region can ensure the energy absorbing device with low peak load and high mean crushing load. The other areas of opening regions affect the first descending and second ascending of the curve. The first rising stage bears the load from the middle edge. [ABSTRACT FROM AUTHOR]

In order to carry out high-precision machining of aerospace structural components with large size, thin wall and complex surface, this paper proposes a novel parallel kinematic machine (PKM) and formulates its semi-analytical theoretical stiffness model considering gravitational effects that is verified by stiffness experiments. From the viewpoint of topology structure, the novel PKM consists of two substructures in terms of the redundant and overconstrained parallel mechanisms that are connected by two interlinked revolute joints. The theoretical stiffness model of the novel PKM is established based upon the virtual work principle and deformation superposition principle after mapping the stiffness models of substructures from joint space to operated space by Jacobian matrices and considering the deformation contributions of interlinked revolute joints to two substructures. Meanwhile, the component gravities are treated as external payloads exerting on the end reference point of the novel PKM resorting to static equivalence principle. This approach is proved by comparing the theoretical stiffness values with experimental stiffness values in the same configurations, which also indicates equivalent gravity can be employed to describe the actual distributed gravities in an acceptable accuracy manner. Finally, on the basis of the verified theoretical stiffness model, the stiffness distributions of the novel PKM are illustrated and the contributions of component gravities to the stiffness of the novel PKM are discussed. [ABSTRACT FROM AUTHOR]

The inherently heterogeneous microstructures of rocks lead to heterogeneity of the deformation distribution within the rock volume. In this study, experiments were conducted on red sandstone specimens with four different pre-existing crack inclinations stressed under uniaxial loading to investigate these features. Acoustic emission and digital image correlation techniques were used to confirm the damage process and obtaining deformation fields, respectively. The results showed that the heterogeneity of the deformation fields in the rock specimens amplifies with increasing stress magnitude, i.e., the displacement field heterogeneity shows two dense bands around the pre-existing crack, and the strain field heterogeneity shows localized regions with a numerical difference (quantified by the normalized standard deviation) and spatial concentration (quantified by the spatial correlation coefficient). The variations in the normalized standard deviation and spatial correlation coefficient were closely related to the damage process. The normalized standard deviation presented four evolution stages: relatively constant low value, steady growth, significant growth, and high rate growth. The spatial correlation coefficient changed from increasing at a relatively constant rate to increasing at a gentle rate and finally increasing rapidly. The evolution rate along with the strain showed two sharp fluctuations. The first could be used as precursor information of the damage. Finally, we confirmed the feasibility of the damage variable obtained from the heterogeneous deformation indicators used to calibrate or form damage evolution laws. [ABSTRACT FROM AUTHOR]

Ultrasound (US) has been introduced to computer-assisted orthopedic surgery for bone registration owing to its advantages of nonionizing radiation, low cost, and noninvasiveness. However, the registration accuracy is limited by US image distortion caused by variations in the acoustic properties of soft tissues. This paper proposes a soft-tissue sound-speed-aware registration method to overcome the above challenge. First, the feature enhancement strategy of multi-channel overlay is proposed for U2-net to improve bone segmentation performance. Secondly, the sound speed of soft tissue is estimated by simulating the bone surface distance map for the update of US-derived points. Finally, an iterative registration strategy is adopted to optimize the registration result. A phantom experiment was conducted using different registration methods for the femur and tibia/fibula. The fiducial registration error (femur, 0.98 ± 0.08 mm (mean ± SD); tibia/fibula, 1.29 ± 0.19 mm) and the target registration error (less than 2.11 mm) showed the high accuracy of the proposed method. The experimental results suggest that the proposed method can be integrated into navigation systems that provide surgeons with accurate 3D navigation information.First, multi-channel input data including the original image, phase symmetric image, and depth weighted map are fused for U2-net model training in the automatic bone segmentation of US images. When US-derived points are obtained, the sound speed of soft tissue is estimated by simulating the bone surface distance map for the update of the locations of US-derived points. An iterative registration strategy based on the cost function of corresponding point distances is adopted to optimize the registration result. Finally, a gold-standard transformation based on artificial fiducials is constructed for method evaluation.Graphical abstract: Ultrasound (US) has been introduced to computer-assisted orthopedic surgery for bone registration owing to its advantages of nonionizing radiation, low cost, and noninvasiveness. However, the registration accuracy is limited by US image distortion caused by variations in the acoustic properties of soft tissues. This paper proposes a soft-tissue sound-speed-aware registration method to overcome the above challenge. First, the feature enhancement strategy of multi-channel overlay is proposed for U2-net to improve bone segmentation performance. Secondly, the sound speed of soft tissue is estimated by simulating the bone surface distance map for the update of US-derived points. Finally, an iterative registration strategy is adopted to optimize the registration result. A phantom experiment was conducted using different registration methods for the femur and tibia/fibula. The fiducial registration error (femur, 0.98 ± 0.08 mm (mean ± SD); tibia/fibula, 1.29 ± 0.19 mm) and the target registration error (less than 2.11 mm) showed the high accuracy of the proposed method. The experimental results suggest that the proposed method can be integrated into navigation systems that provide surgeons with accurate 3D navigation information.First, multi-channel input data including the original image, phase symmetric image, and depth weighted map are fused for U2-net model training in the automatic bone segmentation of US images. When US-derived points are obtained, the sound speed of soft tissue is estimated by simulating the bone surface distance map for the update of the locations of US-derived points. An iterative registration strategy based on the cost function of corresponding point distances is adopted to optimize the registration result. Finally, a gold-standard transformation based on artificial fiducials is constructed for method evaluation. [ABSTRACT FROM AUTHOR]

To develop a natural polysaccharide targeted nanomicelles drug delivery system loaded with the broad-spectrum anti-tumor drug adriamycin (ADM), FA-LNT-OA polymer was synthesized, the ADM/FA-LNT-OA polymer nanomicelles was prepared, and response surface approach was used to optimize the drug loading procedure of the ADM/FA-LNT-OA nanomicelles. Under the optimum conditions, the drug loading ratio was 14.36 ± 0.12% while the entrapment efficiency was 95.17 ± 0.13%. The drug-loaded micelles were spherical, with the size about 170 nm, and the size distribution was uniform. The CMC of ADM/FA-LNT-OA nanomicelles was 48 ± 0.46 μg/mL, their release was more sensitive to pH than that of ADM, and they had good stability. The FA-LNT-OA nanomicelles had good blood compatibility and cell compatibility. In vitro anti-tumor pharmacodynamic studies proved that the IC 50 of ADM/FA-LNT-OA nanomicelles on Hela, ES-2 and A549 cells were 48.49 ± 0.25, 63.56 ± 0.68 and 105.93 ± 17.03 μg/mL respectively. Moreover, the plasma elimination half-life of ADM/FA-LNT-OA nanomicelles was 5.341 h, the T max was 0.083 h, the CL was 0.017 L/h/kg. Compared with the common ADM formulation, the ADM/FA-LNT-OA nanomicelles prolonged the clearance half-life of ADM, decreased the clearance rate, and extended the retention time of ADM in vivo. In conclusion, the above results laid the foundation for the increase of therapeutic effects and reduction of the clinical toxic and side effects of ADM. [Display omitted] • ADM/FA-LNT-OA can be prepared by simple self-assembly. • The cytotoxicity and half-inhibitory concentration were investigated • The nanomicelles can successfully reduce the toxic effects of ADM. [ABSTRACT FROM AUTHOR]

Mobile robots with multi locomotion modes have excellent terrain adaptability. However, traditional multi-locomotion mobile robots are usually actuated by a large number of motors, making their structures heavy and bulky. As a result, the controls become complex, the load-to-mass ratio is low, and the energy consumption is high. Inspired by the bio-mechanism of worms, a novel tensegrity-based multi-locomotion mobile robot, named TJUBot, has been designed. It is actuated by only two motors, yet it has the potential to realize three locomotion modes: earthworm-like, inchworm-like, and tumbling locomotion. The design of these three locomotion modes has been implemented based on kinematic and dynamic models, and the driving law of the two motors under each locomotion mode has been established. Notably, the robot's locomotion has been analyzed under five different terrains. A laboratory prototype of TJUBot has been developed, and experiments demonstrate that the robot can adjust to five types of terrains using the three locomotion modes. For instance, on flat ground, it achieves a maximum velocity of 2.34 BL/min, and it can pass through confined spaces with a minimum height of 1.26 BH. Moreover, the robot can climb slopes with a maximum angle of 7°, overcome obstacles with a maximum height of 0.52 BH, and traverse gaps with a maximum width as 0.35 BL. Herein, BL and BH represent the body length and body height of the robot, respectively. In addition, TJUBot exhibits outstanding performance in terms of its load-to-mass ratio, which is measured at 5.56, and its low energy consumption of 0.69J/m, as observed in experiments. The promising results obtained from these experiments indicate that TJUBot holds significant potential for applications in multi-terrain environments. [Display omitted] • A novel tensegrity robot with three locomotion modes and two actuators is designed. • Multi-locomotion modes design based on kinematic and dynamic models is conducted. • Gait analysis of the multi-locomotion modes under typical terrains is carried out. • Experiments show that the robot has high load-to-mass ratio and low energy consumption. [ABSTRACT FROM AUTHOR]

• Topology characters are parameterized and identified by analytical expression • Algebraic mapping between performance with topology and dimension is constructed • Two algorithms are provided for topology generation and performance modeling • Synchronous optimal design for topologies and dimensions is carried out Parallel robots have attracted much attention from both academia and engineering in last two decades. For development of novel parallel robots, topology and dimensions are brought into sharper focus, which are associated closely and have coupled influence on both motion pattern and performance together. However, currently topology design and dimension design are always performed individually with independent aims, leading to local optimal solutions and difficulties in further modification. Actually, the intrinsic relationship between topology and performance is concerned far from abundant. In this article, a method for topology and dimension synchronous optimization is investigated by employing finite screw theory. Within this approach, two algorithms are formulated to parameterize and deliver topology characters in the same format with dimensions. Topology design and dimension design are converted into a synchronous optimization model with mixed variables and multi-objectives, resulting in global optimal solutions of both optimal topology and dimensions. Topology and dimension synchronous optimization of a kind of 1T2R parallel robots is presented and discussed by comparing with state-of-the-art methods. [ABSTRACT FROM AUTHOR]

• A SPMM with eight stable equilibrium states is proposed. • The kinetostatic model and the multi-stability topologies of SPMM are developed. • The stabilities and switching paths are verified by experiments. A multi-stable flexible mechanism is a mechanical device that can switch to different stable equilibrium states under external power. Most existing multi-stable mechanisms are achieved by splicing bi-stable mechanisms. This paper proposes a novel Spatial Parallel Multi-stable Mechanism (SPMM) without bi-stable mechanisms connected, which even could achieve eight stable equilibrium states and meanwhile contain bi-stable mechanisms' advantages such like simple structure and reliable abilities. To identify the equilibrium states, the paper develops a kinetostatic model using the Energy-Kinematics Differential Equations (EKDE) for the proposed SPMM. Based on the equilibrium states, the multi-stability topologies are drawn referring to direct groups, including the distribution of various equilibrium states and the switching paths between every two stable states. At last, the paper shows the experimental results of a 3D printed prototype and verify the eight-stability behaviors and the switching paths through unstable equilibrium states. A concept of the application in deformable cable protection shell using the SPMM is introduced. [ABSTRACT FROM AUTHOR]

• A design method of parallel flexible mechanisms is proposed. • Principles of stiffness superposition and joint type determination are deduced. • A design example of the RCC and the final structure are presented. Parallel flexible mechanisms with joints can better avoid stress concentration and achieve large motion range compared with integrated-structure ones. However, because of the lack of a mathematical model that can describe the stiffness contribution from the joints to the whole mechanism, the mechanism design is difficult and needs to be addressed. This paper proposes a synchronous design method involving stiffness and topology for parallel flexible mechanisms. To introduce and explain this method, this paper deduces two fundamental principles, namely, "Linear Stiffness Superposition Principle (LSSP)" and "Joint Type Determination Principle (JTDP)", and their deduction processes serve as the cores of the design method. To verify the method's effectiveness, a design process of a Remote Central Compliance (RCC) is presented as an example. [ABSTRACT FROM AUTHOR]

• This paper proposes a structure of a planar three-limb flexible mechanism. • The determination of equilibrium and stability by contour maps is introduced. • The variation of the multi-stability topology of the mechanism is analyzed. In general, the classical multi-stable mechanisms are made of single-loop bi-stable mechanism elements, but this paper proposes a novel structure of a planar three-limb flexible mechanism whose multi-stability is dependent on the structure parameters. The structure of this flexible mechanism is ingeniously designed to have a large selection range of the original limb length, resulting in the variation of the multi-stability distribution and the possible switching paths. To analyze the variation of this flexible mechanism, the paper introduces a method avoiding computational singularity to determine the stability by contour map and a method to draw the multi-stability topology to seek for the possible switching paths. Using these methods, the paper presents the variation of the multi-stability topology of an axisymmetric and two mirror-symmetric planar three-limb flexible mechanisms as the original length of the limbs increases. The results shows the mulita-stability of this flexible mechanism can be determined by the original length of the limbs and limb arrangement. The whole statements provide a theoretical basis for designing and applying such type of flexible multi-stable mechanism. [ABSTRACT FROM AUTHOR]

• A novel modular self-crossing mechanism is proposed. • Kinematic analysis of the self-crossing mechanism is conducted based on FIS theory. • Degree of freedom and gait of self-crossing locomotion is obtained. • Simulation is carried out to prove feasibility of self-crossing mechanism. In this paper, a novel mobile mechanism based on Bennett mechanism is proposed, which can realize self-crossing locomotion. Unlike the most of the self-crossing mechanisms, the proposed mechanism can be assembled modularly, which has better environment adaptability. Firstly, on the basis of revealing mechanism of the self-crossing movement, configuration of the self-crossing mechanism is designed. The mechanism consists of n Bennett mechanisms connected in series by 2(n -1) 3 R limbs that are symmetrically distributed on both sides of n Bennett mechanisms. Then, kinematic analysis of the mechanism is carried out based on finite and instantaneous screw theory, including mobility analysis and gait analysis. For the former, the number of degrees of freedom that the mechanism can achieve self-crossing locomotion is obtained, and for the latter, the trajectory of end point of the mechanism in the self-crossing movement is obtained. Finally, On the basis of theoretical analysis, simulation is conducted, and the results show that the proposed novel mechanism can realize self-crossing locomotion without interference, which verified the rationality of the mechanism. This paper provides a useful reference for the design and analysis of self-crossing mobile mechanism. [ABSTRACT FROM AUTHOR]

• A direct and analytical kinematic and force modeling method is applied. • Complete dynamic model of an over-constrained tracking mechanism is developed. • Practical dynamic identification is performed compromising precision and efficiency. • Predicted dynamic model for real-time control system is validated by experiments. To improve tracking precision against complex external forces in the working environment, dynamic model-based control algorithms are widely used in tracking mechanisms. As a foundation of the real-time dynamic control system, this paper focuses on the complete predicted dynamic modelling and dynamic parameter identification of a 2-DoF over-constrained tracking parallel mechanism. Firstly, the kinematic model is obtained by differential mapping of the topology models based on finite and instantaneous screws (FIS). Referred to virtual work principle, dynamic equation is constructed. To reduce the computation cost in practice, a linear model involving inertial and friction parameters is formulated for dynamic identification. A direct identification method is applied and all the parameters are obtained at the same time. Experiments are performed to show the accuracy and efficiency of the identification results. The contributions of the paper lie in 1) a concise method for constructing velocity and acceleration models of components is provided without tedious analysis 2) complete dynamic model of an over-constrained tracking parallel mechanism is developed 3) practical dynamic identification process is carried out compromising between precision and efficiency. [ABSTRACT FROM AUTHOR]

In order to obtain the real material parameters of heterogeneous rock, the material parameters of red sandstone specimens under uniaxial compression tests are inverted based on the Digital Image Correlation (DIC) method and the Finite Element Model Updating (FEMU) method. The DIC method is employed to calculate the displacement field of red sandstone specimens during uniaxial compression loading. Concurrently, a uniaxial compression elastic-plastic finite element numerical model with non-uniform material parameters is developed based on the FEMU method. The model adopts the Mohr-Coulomb yield criterion and adjusts the boundary conditions in real-time to maintain consistency with the test. The vertical displacement field of the numerical model is juxtaposed with that of the test to construct the objective function. Optimization is achieved using the Artificial Fish Swarm algorithm, which enables the acquisition of the non-uniform distribution and evolution process of the material parameters of specimens at different loading moments. The results indicate that this method can spatially obtain the non-uniform distribution field of material parameters and temporally track the evolution of material parameters during the loading process. This research lays a solid foundation for enhancing the accuracy of intelligent coal mining and dynamic disaster monitoring and early warning in coal mines., (© 2023. The Author(s).)

A microseismic localization algorithm that combines global search and local optimization is proposed. The Fewer Conditions Trigger Difference (FCTD) objective function of global search and local optimization is constructed, the execution process of the algorithm is described by numerical simulation, and the global search and local optimization microseismic localization algorithm is verified and applied by field data analysis. The results show that: (1) the global search and local optimization methods have fast search speed in the global range, high convergence accuracy and stable localization results in the local range, and high localization accuracy and stability without relying on the velocity model and initial values in the process of search. (2) By comparing the localization results of different localization methods, the global search and local optimization algorithms have better localization results., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 Published by Elsevier Ltd.)

Purpose: Computer-assisted high tibial osteotomy (HTO) is a frequently used treatment technique for lower extremity orthopedics, and its small incision and low exposure area are major limitations in tibial registration. This work combines skin surface features and gives a suitable registration algorithm based on Iterative Closest Points (ICP) algorithm to improve registration results. Furthermore, the precision, stability and efficiency of the described method is evaluated., Methods: After the initialization stage, the bone surface and skin surface data are combined to construct registration features. Then, a steepest perturbation search method is performed after the ICP algorithm (SPS-ICP) to obtain the optimal transformation through several iterations. Finally, the registration result is evaluated by establishing ground-truth through manual landmarks., Results: Phantom experiments including simulated human tissue show that the proximal fiducial registration error (FRE) of our method can reach 0.80 ± 0.30 mm (mean ± SD) with an overall rotational error < 1° and translational error < 1.5 mm. Furthermore, it remains stable when the point set is sparse. The average registration time is less than 40 s to ensure the high efficiency of surgical operation., Conclusions: The approach fully describes a well-defined framework without additional imaging acquisition equipment for Computer-assisted HTO. By the experiment on the basis of a phantom with simulated soft tissue, the proposed method enables the accurate and robust registration of the tibia, and its computation time meets the demands of surgery., (© 2022. CARS.)

Through the improvement of supporting structure and the utilization of the interaction between surrounding rock and supporting structure, the synergistic system of energy-absorbing yielding anti-impact supporting structure and surrounding rock is established. The process of energy absorption device, energy-absorbing yielding anti-impact supporting structure and synergistic system under impact is simulated to analyze the properties of them. The following conclusions could be drawn. The deformation and yielding process under compression of energy absorption device is divided into five stages. Compared with the traditional supporting structure, the energy-absorbing yielding anti-impact supporting structure has the reaction force with lower value and smaller fluctuation range before the deformation of the energy absorption device reaches the third ascending section. The synergy between surrounding rock and supporting structure plays an important role in roadway support. Compared with the supporting structure without surrounding rock, the reaction force of the supporting structure in the synergistic system is lower, and a stationary stage is added in the early stage of the reaction force curve., (© 2022. The Author(s).)

This work aims to study the construction of reverse aspirin-loaded micelles prepared from amphiphilic PEG-PLA-SA triblock copolymers and the optimization of the preparation process. Using polyethylene glycol (PEG) as the initiator, ring-opening polymerization of L-lactide (L-LA) was used to prepare PEG-PLA diblock copolymers. Final product PEG-PLA-SA triblock copolymers were prepared by the reaction of stearic acid (SA) and PEG-PLA catalyzed by 4-dimethylaminopyridine (DMAP) and N,N'-Dicyclohexylcarbodiimide (DCC). Fourier transform infrared spectrometer (FT-IR) was used to characterize the product structure. PEG-PLA-SA triblock copolymers self-assembled in toluene/ethanol/water system to form reverse micelles, which could encapsulate aspirin into a hydrophilic core. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to determine the size and morphology of reverse micelles. The results showed that the reverse micelles are spherical, with a particle size of less than 70 nm. Response surface analysis method was applied to optimize the preparation process of PEG-PLA-SA. In vitro drug release was achieved by embedding reverse aspirin-loaded micelles in the biocompatible membrane in phosphate buffer saline (PBS) at 37°C. In the first 8 h, the drug release rate of the triblock copolymers was slower than that of the diblock copolymers. After 8 h, the drug release rate of both tended to be flat. The stability of aspirin-loaded reverse micelles was studied through accelerated test. These results indicate that reverse micelle PEG-PLA-SA may be a promising carrier for hydrophilic drugs like aspirin., Competing Interests: No potential conflict of interest was reported by the authors., (© 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Papillary carcinoma is the most common type of thyroid cancer responsible for significant number of mortalities across the globe. This study was conducted to investigate the role and therapeutic implications of microRNA-7 in human papillary carcinoma. Gene expression analysis was carried out through quantitative real time PCR method. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was performed to determine the cell proliferation. Clonogenic assay was used to assess the colony forming ability of cancer cells. Cell apoptosis was analyzed by 4',6-diamidino-2-phenylindole (DAPI), acridine orange/ethidium bromide (AO/EB) and annexin V/PI staining assays. Migration of cancer cells was estimated through scratch heal assay and cell invasion was determined by transwell assay method. Western blotting was done to examine the protein expression. Xenografted mice models were employed to examine the effects of miR-7 overexpression in vivo . Results showed miR-7 to be significantly ( P < 0.05) repressed in papillary carcinoma. Cancer cell proliferation was inhibited by miR-7 through induction of apoptotic cell death as revealed by DAPI, AO/EB and annexin V/PI staining assays. The colony forming potential of cancer cells also decreased under miR-7 overexpression. miR-7 overexpression also inhibited the migration and invasion of cancer cells. Bcl-2 was identified as the intracellular target of miR-7 and regulatory effects of miR-7 were seen to be exerted through translation repression of Bcl-2. The results of xenograft study revealed miR-7 overexpression significantly ( P < 0.05) suppressed the growth of the tumor in vivo . The results point towards the therapeutic implications of miR-7 in the management of papillary carcinoma., Competing Interests: None., (AJTR Copyright © 2020.)

A series of novel 2-(6-thioxo-1,3,5-thiadiazinan-3-yl)-N'-phenylacethydrazide derivatives were designed, synthesized and evaluated for their antifungal activities against Fusarium graminearum (Fg), Rhizoctonia solani (Rs), Botrytis cinerea (Bc) and Colletotrichum capsici (Cc). The bioassay results in vitro showed that most of the title compounds exhibited impressive antifungal activities against the above plant fungi. Particularly, the compounds 5c, 5f, 5g, 5i, 5m and 5p displayed desirable anti-Rs activities, with the corresponding EC 50 values of 0.37, 0.32, 0.49, 0.50, 0.46 and 0.45 µg/mL, respectively, which are superior to the positive control carbendazim (0.55 µg/mL). Further in vivo bioassay results showed that the anti-Rs activity of title compound 5f at 200 µg/mL reached 95.84% on detached rice leaves and 93.96% on rice plants. Featuring convenient synthesis, novel structures and desirable antifungal activity, these 2-(6-thioxo-1,3,5-thiadiazinan-3-yl)-N'-phenylacethydrazide derivatives could be further studied as the potential candidates of novel agricultural fungicides.

Currently, accumulating documents have paid great attention to the critical role of long non-coding RNAs. The long non-coding RNAs DLEU1 has been demonstrated to be dysregulated in many solid tumors and hematological malignancies. However, the detailed descriptions about its potential roles and molecular mechanism in gastric cancer (GC) are still blurry. As for our research, it was found out that DLEU1 was observably intensified in GC tissues and cell lines. And highly expressed DLEU1 was relevant to tumor size, advanced stage of pathology and lymph node metastasis in GC patients. Silenced DLEU1 obviously suppressed proliferation via leading to the cell cycle arrest and inducing cell apoptosis of GC. Furthermore, mechanistic experiments uncovered that DLEU1 could recruit LSD1 (lysine specific demethylase 1) to the promoter regions of KLF2 and then suppressed its transcription. In addition, rescue assays revealed that the oncogenic function mediated by DLEU1 in GC was partly by regulating KLF2. Collectively, our findings manifested that DLEU1 might serve as an oncogene in GC.

Using gas-chromatography/mass spectrometry (GC-MS) method dating data ( 210 Pb and 137 Cs) and OCPs signatures, the temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was investigated in dated sediment core from Baoxianghe reservoir in Dianchi watershed, Southwest China. The concentrations of total PAHs were in the range of 162.3-762.2 ng g -1 from 1945 to 2013. There showed an obvious increase from 1960s to 2000s. The distributions of PAHs were influenced by local population and Gross Domestic Product (GDP) during the period between1962 and 2004. PAHs sources changed from biomass or domestic coal combustion (before 1980) to liquid fossil fuel combustion (after 1980). Total toxic toxicity equivalents (TEQs) of the carcinogenic PAHs were very low (3.03-28.08 ng g -1 ).

To study high-frequency ultrasound features and pathological characteristics of medullary thyroid carcinoma (medullary thyroid carcinoma, MTC) with the purpose to improve the diagnostic accuracy of this disease. The clinical data of 20 cases of patients with MTC confirmed by the clinical surgery were retrospectively analyzed. And the high-frequency ultrasound features were analyzed and compared with the pathological characteristics. There were 16 cases with tumor invasion into one side of the thyroid gland; 17 cases with tumor in the middle-upper pole of the thyroid gland. And 8 cases were detected with uneven echo of high frequency ultrasound appearance and pathological manifestations of cystic degeneration to necrosis seen under the light microscope or normal thyroid tissue within part of the lump. 16 cases were tested with even echo of high frequency ultrasound appearance, and tumor cells were formed in the solid and block-like shape under the light microscope. And 18 cases were manifested with low echo, with proliferation of fibrous tissue within the intercellular substance under the light microscope. 18 cases could be seen the calcification points and often amyloid-like content deposited in the intercellular substance seen under the light microscope. In addition, the pathological manifestations of the 8 cases combined with lymph node metastasis were the "lash tumor" of the metastatic lymph nodes and primary tumor. MTC was commonly located in the middle-upper region of the thyroid gland and in one leaf of the thyroid gland, combined with lymph node metastasis. The high frequency ultrasound appearance was the even low-echo tumor in round or quasi-circular shape, with obscure boundary and often combined with rough calcification. High frequency ultrasound could be used as the prior physical diagnostic method for medullary thyroid carcinoma.

Objective: To study the effect of xenotransplantation with pig parathyroid cells, which was prepared using cell microencapsulation technique, on the treatment of hypoparathyroidism in rats without immunosuppressor., Methods: Parathyroid cells were isolated from 10 healthy newborn pigs and encapsulated in alginate-polylysine-alginate (APA) membranes. Thirty-two aparathyroid Wistar rats were randomly allocated to microcapsule, non-microcapsule, empty microcapsule, and control groups. Each rat was injected intraperitoneally with encapsulated porcine parathyroid cells, free porcine parathyroid cells, empty capsules or 0.9% NaCl, respectively. Total serum calcium and parathyroid hormone levels were monitored continuously for 40 weeks. And then, the transplant beds were retrieved and subjected to morphologic and electron microscopic examination., Results: In those animals xenotransplanted with microencapsulated porcine parathyroid cells, the calcium and PTH levels were consistently within the normal range during the 40 weeks. In contrast, no therapeutic effects were observed in rats in the non-microcapsule group. Furthermore, neither empty capsules nor 0.9% NaCl were shown to have any effect on the recipient's serum calcium or PTH levels. After 40 weeks, electron microscopic examination demonstrated that the parathyroid cells within the microcapsules had survived well in vivo., Conclusions: Xenotransplantation of microencapsulated newborn pig parathyroid cells can successfully treat hypoparathyroidism in rats without using immunosuppressive drugs. The results of this study show the possible clinical use of microencapsulated porcine parathyroid cells.