EVOLVING CONCEPTS OF CHONDROGENIC DIFFERENTIATION: HISTORY, STATE-OF-THE-ART AND FUTURE PERSPECTIVES

As a cell source, multipotent mesenchymal stromal cells or mesenchymal stem cells (MSCs) are promising candidates for chondrogenic differentiation and subsequent cartilage regeneration. From previous literature, it is known that chondrogenic differentiation of MSCs inevitably leads to hypertrophy and subsequent endochondral ossification. In this review, we examine the history of currently established protocols of chondrogenic differentiation and elaborate on the roles of individual components of chondrogenic differentiation medium. We also summarise the effects of physical, chemical and biological factors involved, and propose potential strategies to differentiate MSCs into articular chondrocytes with homogenous mature phenotypes through spatial-temporal incorporation of cell differentiation and chondrogenesis

Model testing on rainfall-induced landslide of loose soil in Wenchuan earthquake region

This study investigates the formation process of rainfall-induced landslide for slopes composed of loose soil in the Wenchuan earthquake region. Experimental investigations have been performed on the landslide's formation and the variation of the controlling soil parameters under various artificial rainfall conditions. The landslide triggering mechanisms can be described in the following way. Firstly, the large porosity of the loose soil facilitated the infiltration of water, which increased the pore water pressure and reduced the shear strength of the soil significantly. In addition, the rainfalls probably caused the concentration of finer particles at a certain depth of the valley slopes. This concentration within the soil increased the pore water pressure significantly, and consequently reduced both the porosity ratio and permeability. Therefore, when the pore water pressure reached a critical state, the effective shear strength of the soil diminished, inducing the landslide's formation

Enhancement of the performance of covalently immobilized lipase using alcohol quenching technology

In order to modulate the microenvironment for enzyme covalently attached on support and improve the covalent immobilization of lipase, alcohol molecules were used to quench the excessive activated functional group on support surface. Effects of kind and content of alcohol molecules on the relative activity of the immobilized enzyme and the characteristics of the immobilized enzyme were examined carefully. The maximum relative activities of the immobilized lipase quenched with methanol and npropanol, were 224.3 and 224.5%, respectively, both 1.96 fold of the just immobilized lipase which was not quenched with alcohol. Residual activity of the immobilized lipase using methanol to quench the excessive activated groups on support surface was 65.9% after heating at 50°C for 60 h, 1.29 folds higher than that of the ordinarily immobilized lipase (with no blockage). Alcohol molecules could alter the physical and chemical properties to modulate the microenvironment on support surface bychanging the hydrophobicity. Suitable microenvironment, resulted from the methanol quenching the excessive active groups, would further favor the activity and the stability of lipase at higher temperature

Low-Symmetry Rhombohedral GeTe Thermoelectrics

High-symmetry thermoelectric materials usually have the advantage of very high band degeneracy, while low-symmetry thermoelectrics have the advantage of very low lattice thermal conductivity. If the symmetry breaking of band degeneracy is small, both effects may be realized simultaneously. Here we demonstrate this principle in rhombohedral GeTe alloys, having a slightly reduced symmetry from its cubic structure, to realize a record figure of merit (zT ∼ 2.4) at 600 K. This is enabled by the control of rhombohedral distortion in crystal structure for engineering the split low-symmetry bands to be converged and the resultant compositional complexity for simultaneously reducing the lattice thermal conductivity. Device ZT as high as 1.3 in the rhombohedral phase and 1.5 over the entire working temperature range of GeTe alloys make this material the most efficient thermoelectric to date. This work paves the way for exploring low-symmetry materials as efficient thermoelectrics. Thermoelectric materials enable a heat flow to be directly converted to a flow of charge carriers for generating electricity. The crystal structure symmetry is one of the most fundamental parameters determining the properties of a crystalline material including thermoelectrics. The common belief currently held is that high-symmetry materials are usually good for thermoelectrics, leading to great efforts having historically been focused on GeTe alloys in a high-symmetry cubic structure. Here we show a slight reduction of crystal structure symmetry of GeTe alloys from cubic to rhombohedral, enabling a rearrangement in electronic bands for more transporting channels of charge carriers and many imperfections for more blocking centers of heat-energy carriers (phonons). This leads to the discovery of rhombohedral GeTe alloys as the most efficient thermoelectric materials to date, opening new possibilities for low-symmetry thermoelectric materials. Cubic GeTe thermoelectrics have been historically focused on, while this work utilizes a slight symmetry-breaking strategy to converge the split valence bands, to reduce the lattice thermal conductivity and therefore realize a record thermoelectric performance, all enabled in GeTe in a rhombohedral structure. This not only promotes GeTe alloys as excellent materials for thermoelectric power generation below 800 K, but also expands low-symmetry materials as efficient thermoelectrics

Experimental study of breathers and rogue waves generated by random waves over non-uniform bathymetry

Experimental results describing random, uni-directional, long crested, water waves over non-uniform bathymetry confirm the formation of stable coherent wave packages traveling with almost uniform group velocity. The waves are generated with JONSWAP spectrum for various steepness, height and constant period. A set of statistical procedures were applied to the experimental data, including the space and time variation of kurtosis, skewness, BFI, Fourier and moving Fourier spectra, and probability distribution of wave heights. Stable wave packages formed out of the random field and traveling over shoals, valleys and slopes were compared with exact solutions of the NLS equation resulting in good matches and demonstrating that these packages are very similar to deep water breathers solutions, surviving over the non-uniform bathymetry. We also present events of formation of rogue waves over those regions where the BFI, kurtosis and skewness coefficients have maximal values.Comment: 41 pages, 21 figure

The Expression and Roles of Nde1 and Ndel1 in the Adult Mammalian Central Nervous System

Open Access funded by Wellcome Trust Under a Creative Commons license Acknowledgments We thank Prof Angelo Sementilli, Department of Pathology, Universidade Metropolitana de Santos, SP, Brazil, for the human sample collection. This study is funded by Scottish Universities Life Sciences Alliance (HR07019 to S. Shen and C.D. McCaig), Medical Research Scotland (384 FRG to B. Lang, United Kingdom), Tenovus Scotland (G12/25 to B. Lang), Sino-UK Higher Education Research Partnership for PhD Studies (C.D. McCaig and Y.Q. Ding) and Wellcome Trust (WT081633MA-NCE to P.J.A. McCaffery, United Kingdom).Peer reviewedPublisher PD

Johnson-Cook model for TC4 titanium alloy based on compression experiment

To obtain the exact mechanical properties of TC4 titanium alloy, the compression experiments on TC4 titanium alloy at different strain rates (10-2,10-3,10-4 s-1) were performed at room-temperature on the MTS-810 electrohydraulic servo material testing machine. The data of TC4 titanium alloy compression experiments at different rates were obtained. And furthermore Johnson-Cook constitutive model is established. Due to different conditions, the equation is simplified, the constitutive parameters are obtained by step-by-step estimation method, and the Johnson- Cook (JC) constitutive model of TC4 titanium alloy at room temperature is established. The prediction results of the model were compared with the experimental data, the prediction curve is in good agreement, which verifies the feasibility of the model

Johnson-Cook model for TC4 titanium alloy based on compression experiment

To obtain the exact mechanical properties of TC4 titanium alloy, the compression experiments on TC4 titanium alloy at different strain rates (10-2,10-3,10-4 s-1) were performed at room-temperature on the MTS-810 electrohydraulic servo material testing machine. The data of TC4 titanium alloy compression experiments at different rates were obtained. And furthermore Johnson-Cook constitutive model is established. Due to different conditions, the equation is simplified, the constitutive parameters are obtained by step-by-step estimation method, and the Johnson- Cook (JC) constitutive model of TC4 titanium alloy at room temperature is established. The prediction results of the model were compared with the experimental data, the prediction curve is in good agreement, which verifies the feasibility of the model

A general model for collaboration networks

In this paper, we propose a general model for collaboration networks. Depending on a single free parameter "{\bf preferential exponent}", this model interpolates between networks with a scale-free and an exponential degree distribution. The degree distribution in the present networks can be roughly classified into four patterns, all of which are observed in empirical data. And this model exhibits small-world effect, which means the corresponding networks are of very short average distance and highly large clustering coefficient. More interesting, we find a peak distribution of act-size from empirical data which has not been emphasized before of some collaboration networks. Our model can produce the peak act-size distribution naturally that agrees with the empirical data well.Comment: 10 pages, 10 figure