Search

The objective of this article is to investigate the effect of the vibration mixing process (VMP) on the performance of cement stabilized recycled aggregate (CSRA). The ordinary mixing process (OMP) was also used for comparative analysis with the VMP. The performance of CSRA with different cement content was tested and comprehensively analyzed by the unconfined compressive strength test, dry shrinkage test, and temperature shrinkage test. The results showed that compared with OMP, VMP can greatly improve the compressive strength, dry shrinkage, and temperature shrinkage properties of CSRA. The optimum parameters of vibration time and vibration frequency in VMP were 30 s and 40 Hz, respectively. The reason why VMP can improve the performance of CSRA was that VMP strengthened the aggregate and interface transition zone and introduced microbubbles to optimize the pore structure. [ABSTRACT FROM AUTHOR]

The objective of this article is to investigate the effect of the vibration mixing process (VMP) on the performance of cement stabilized recycled aggregate (CSRA). The ordinary mixing process (OMP) was also used for comparative analysis with the VMP. The performance of CSRA with different cement content was tested and comprehensively analyzed by the unconfined compressive strength test, dry shrinkage test, and temperature shrinkage test. The results showed that compared with OMP, VMP can greatly improve the compressive strength, dry shrinkage, and temperature shrinkage properties of CSRA. The optimum parameters of vibration time and vibration frequency in VMP were 30 s and 40 Hz, respectively. The reason why VMP can improve the performance of CSRA was that VMP strengthened the aggregate and interface transition zone and introduced microbubbles to optimize the pore structure. [ABSTRACT FROM AUTHOR]

Fibroblast growth factor 21 (FGF21), a secretion protein, functions as a pivotal regulator of energy metabolism and is being considered as a therapeutic candidate in metabolic syndromes. However, the roles of FGF21 in myogenic differentiation and cell cycle remain obscure. In this study, we investigated the function of FGF21 in myogenesis and cell cycle exit using C2C12 cell line. Our data showed that the expression of myogenic genes as well as cell cycle exit genes was increased after FGF21 overexpression, and FGF21 overexpression induces cell cycle arrest. Moreover, cell cycle genes were decreased in FGF21 overexpression cells while they were increased in FGF21 knockdown cells. Further, FGF21/P53/p21/Cyclin-CDK has been suggested as the key pathway for cell cycle exit mediated by FGF21 in C2C12 cells. Also, we deduce that FGF21 promotes the initiation of myogenic differentiation mainly through enhancing cell cycle exit of C2C12 cells. Taken together, our results demonstrated that FGF21 promotes cell cycle exit and enhances myogenic differentiation of C2C12 cells. This study provided new evidence that FGF21 promotes myogenic differentiation, which could be useful for better understanding the roles of FGF21 in myogenesis. [ABSTRACT FROM AUTHOR]

A numerical finite element (FE) analysis technology is presented for efficient and reliable solutions of rock with hydraulic-mechanical (HM) coupling, researching the seepage characteristics and simulating the damage evolution of rock. To be in accord with the actual situation, the rock is naturally viewed as heterogeneous material, in which Young’s modulus, permeability, and strength property obey the typical Weibull distribution function. The classic Biot constitutive relation for rock as porous medium is introduced to establish a set of equations coupling with elastic solid deformation and seepage flow. The rock is subsequently developed into a novel conceptual and practical model considering the damage evolution of Young’s modulus and permeability, in which comprehensive utilization of several other auxiliary technologies, for example, the Drucker-Prager strength criterion, the statistical strength theory, and the continuum damage evolution, yields the damage variable calculating technology. To this end, an effective and reliable numerical FE analysis strategy is established. Numerical examples are given to show that the proposed method can establish heterogeneous rock model and be suitable for different load conditions and furthermore to demonstrate the effectiveness and reliability in the seepage and damage characteristics analysis for rock. [ABSTRACT FROM AUTHOR]

Tilting pad bearings offer unique dynamic stability enabling successful deployment of high-speed rotating machinery. The model of dynamic stiffness, damping, and added mass coefficients is often used for rotordynamic analyses, and this method does not suffice to describe the dynamic behaviour due to the nonlinear effects of oil film force under larger shaft vibration or vertical rotor conditions. The objective of this paper is to present a nonlinear oil force model for finite length tilting pad journal bearings. An approximate analytic oil film force model was established by analysing the dynamic characteristic of oil film of a single pad journal bearing using variable separation method under the dynamic π oil film boundary condition. And an oil film force model of a four-tilting-pad journal bearing was established by using the pad assembly technique and considering pad tilting angle. The validity of the model established was proved by analyzing the distribution of oil film pressure and the locus of journal centre for tilting pad journal bearings and by comparing the model established in this paper with the model established using finite difference method. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) simulation was performed to investigate the structure and dielectric permittivity of poly(vinylidene fluoride)- (PVDF-) based composites with different contents of barium titanate (BT). The β-phase PVDF model with 100 structural units and the spherical BT particle model with a radius of 0.495 nm were built and applied in the initial models with three PVDF macromolecular chains and BT particles for the MD simulations of the BT/PVDF composites. The influences of BT content on the morphological structure, the free volume fraction, and glass transition temperature of the composites were explored according to the simulated results and the experimental ones of X-ray diffraction (XRD) and scanning electron microscope (SEM). A model was proposed to predict the static dielectric permittivity of the composites, the results of which were compared with the Cole-Cole fitting results of dielectric spectroscopy. Attempts were made to reveal the structure evolution and the micropolarization mechanism with the increasing content of BT. [ABSTRACT FROM AUTHOR]