Therapeutic effects of Clostridium butyricum on experimental colitis induced by oxazolone in rats

AIM： To evaluate the therapeutic effects of a probiotic supplement （Clostridium butyricum, CGMCC0313 ） in a chemically-induced rat model of experimental colitis. METHODS： An experimental ulcerative colitis model was established by rectal injection of oxazolone into the colon of 40 Wistar rats randomly divided into four groups. The positive control group was sacrificed 3 d after colitis onset. The remaining groups were fed daily with either 2 mL of C. butyricum （2.3 × 10^11 CFU/L）, 2 mL of mesalamine （100 g/L）, or 1 mL of sodium butyrate （50 mmol/L） for 21 d. The animals＇ body weight, behavior, and bowel movements were recorded weekly. After sacrifice, visual and microscopic observations of pathological changes of colon tissue were made, body weight and wet colon mass index were measured and recorded, and serum levels of interleukin-23 （IL-23） and TNF-α were measured using ELISA. Expression of calcitonin gene-related peptide in colon tissue was measured by RT-PCR. Finally, changes in rat intestinal microflora status were measured in all groups.lowered the serum levels of both IL-23 and tumor necrosis factor-α （TNF-α） with similar or even better efficiency than that of mesalamine or sodium butyrate. The rat intestinal flora appeared to recover more quickly in the group treated with C. butyricum than in the mesalamine and sodium butyrate groups. Finally, we found that the expression level of calcitonin gene related peptide was elevated in colon tissue in the sodium butyrate treated group but not in the C. butyricum or mesalamine treated groups, indicating a sensitization of colon following sodium butyrate treatment. CONCLUSION： In our experimental colitis model, treatment with C. butyricum CGMCC0313, a probiotic supplement, is at least as efficient as treatment with mesalamine.

Motion-force Transmissibility Characteristic Analysis of a Redundantly Actuated and Overconstrained Parallel Machine

This paper presents a novel 1T2R three degrees of freedom redundantly actuated and overconstrained ■parallel machining head(■denotes the active prismatic joint), which can construct 5-axis hybrid machine to complete high speed freedom surface milling for large complex structural components in aerospace. Firstly, based on the screw theory, the mobility of the proposed parallel manipulator is briefly analysed. Secondly, the kinematic inverse position and the parasitic motion of the parallel manipulator are explicitly expressed. Furthermore, motion-force transmission performance evaluation indices are derived in detail via an alternative approach based on the screw theory. More importantly, a simple method for quickly solving the maximum virtual power coefficient is proposed, and the motion-force transmission performance evaluation index is greatly improved. To evaluate the kinematic performance, its workspace is calculated. With numerical examples, performance distribution atlases of the manipulator are depicted visually. The corresponding results illustrate that the proposed parallel manipulator has better orientation workspace and superior motion-force transmission performance than the 2 PRU-PRS parallel manipulator, which proves the validity and applicability of applying this manipulator as a machining head.

Dynamic Performance Evaluation of a Redundantly Actuated and Over-constrained Parallel Manipulator

This paper presents a redundantly actuated and over-constrained 2 RPU-2 SPR parallel manipulator with two rotational and one translational coupling degrees of freedom.The kinematics analysis is firstly carried out and the mapping relationship of the velocity,acceleration and the independent parameters between the actuator joint and the moving platform are deduced by using the vector dot product and cross product operation.By employing d′Alembert′s principle and the principle of virtual work,the dynamics equilibrium equation is derived,and the simplified dynamics mathematical model of the parallel manipulator is further derived.Simultaneously,the generalized inertia matrix which can characterize the acceleration performance between joint space and operation space is further separated,and the performance indices including the dynamics dexterity,inertia coupling characteristics,energy transmission efficiency and driving force/torque balance are introduced.The analysis results show that the proposed redundantly actuated and over-constrained 2 RPU-2 SPR parallel manipulator in comparison with the existing non-redundant one has better dynamic comprehensive performance,which can be demonstrated practically by the successful application of the parallel kinematic machine head module of the hybrid machine tool.

Type Synthesis and Kinematics Performance Analysis of a Class of 3T2R Parallel Mechanisms with Large Output Rotational Angles

Based on Lie group theory and the integration of configuration, a class of 3T2 R(T denotes translation and R denotes rotation) parallel mechanisms with large output rotational angles is synthesized through a five degree of freedom single limb evolving into two five degree of freedom limbs and constraint coupling of each kinematics chain. A kind of 3T2 R parallel mechanisms with large rotational angles was selected from type synthesis of 3T2 R parallel mechanisms, inverse kinematics and velocity Jacobian matrix of the parallel mechanism are established. The performance indices including workspace, rotational capacity, singularity and dexterity of the parallel mechanism are analyzed. The results show that the parallel mechanism has not only large output rotational angles but also better dexterity.

Design and Analysis of a Novel Hybrid Processing Robot Mechanism

In order to satisfy the requirements of large workspace and high dexterity for processing equipment of oversized cylindrical boxes′spherical crown surfaces in the aerospace industry,a novel serial-parallel hybrid processing robot mechanism is proposed.The degrees of freedom of the 5PUS-(2UR)PU parallel mechanism are obtained by using the screw theory.The inverse kinematics of the hybrid mechanism are analyzed and the velocity Jacobian matrix is established.Then,the constraints of the main factors influencing workspace of the mechanism are given,and the position and posture workspace are obtained.Next,the dexterity and stiffness performance of the mechanism is analyzed based on the Jacobian matrix.The virtual prototype is established,and the theoretical calculation and simulation analysis of the hybrid mechanism with arc curve as the processing trajectory are carried out by using Matlab and Adams software.The research results show that the mechanism can satisfy the requirements of large workspace and high dexterity of oversized cylindrical boxes′spherical crown surface processing,and has feasibility and practical application value.

Type Synthesis and Dynamics Performance Evaluation of a Class of 5-DOF Redundantly Actuated Parallel Mechanisms

This paper presents a five degree of freedom(5-DOF)redundantly actuated parallel mechanism(PM)for the parallel machining head of a machine tool.A 5-DOF single kinematic chain is evolved into a secondary kinematic chain based on Lie group theory and a configuration evolution method.The evolutional chain and four 6-DOF kinematic chain SPS(S represents spherical joint and P represents prismatic joint)or UPS(U represents universal joint)can be combined into four classes of 5-DOF redundantly actuated parallel mechanisms.That SPS-(2UPR)R(R represents revolute joint)redundantly actuated parallel mechanism is selected and is applied to the parallel machining head of the machine tool.All formulas of the 4SPS-(2UPR)R mechanism are deduced.The dynamic model of the mechanism is shown to be correct by Matlab and automatic dynamic analysis of mechanical systems(ADAMS)under no-load conditions.The dynamic performance evaluation indexes including energy transmission efficiency and acceleration performance evaluation are analyzed.The results show that the 4SPS-(2UPR)R mechanism can be applied to a parallel machining head and have good dynamic performance.