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Interestingly, 3A6 cells exposed to Fmoc-GGHAVDI (1d) peptide solution showed an enhanced expression level of chondrogenic specific marker collagen-II (Col-II) in comparison with other peptide sequences. In contrast, when 3A6 cells were encapsulated in the hydrogel blend (2/1c), the peptide sequence with flanking amino acid serine exhibited greater material stiffness with enhanced glycosaminoglycan (GAG) distribution and high expression levels of chondrogenic specific markers for the cartilage-specific matrix. This suggests that substrate stiffness and peptide sequences can influence stem cell differentiation. The hydrogel with the HAV motif with greater substrate stiffness (2/1c) can promote the chondrogenic differentiation of human mesenchymal stem cells which can be a promising candidate for 3D cell culture and stem cell-based cartilage regeneration therapies.Casein is a naturally derived amino group (-NH2) rich protein, that enables surface functionalization leading to hydrophilicity, which in turn facilitates better cell adhesion. Casein obtained from either commercial β-casein rich skim milk (A2 milk) or dissolved air flotation (DAF) technology was tested for its potential for tissue engineering applications in a comparative study. A novel biodegradable biomaterial was synthesized from casein by chemically modifying with methacrylic anhydride (MA) and combined with polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) blend. The resulting methacrylated casein (CasMA) with the two polymers was processed into porous scaffolds with low and high MA concentrations to demonstrate CasMA's ease of modification and reproducibility. Fourier Transform Infrared Microscopy (FTIR) and Proton Nuclear Magnetic Resonance (1H NMR) revealed the presence of all the components and the successful modification of casein. The rheological and morphological analysis presented viscous behaviour and columnar hollow tube-like microstructures in agreement with the biomaterials' swelling and biodegradation behaviour. The live/dead in vitro assay showed high cell viability that agreed with the cell proliferation (MTT) assay in vitro, which indicated increased proliferation upon casein modification at appropriate biomaterial concentrations and volumes. This study not only showed a possible mechanism of casein methacrylation but also presented the potential use of waste materials like DAF-casein as a value-added product for tissue engineering applications.Nanocrystalline (NC) metals suffer from an intrinsic thermal instability; their crystalline grains undergo rapid coarsening during processing treatments or under service conditions. Grain boundary (GB) solute segregation has been proposed to mitigate grain growth and thermally stabilize the grain structures of NC metals. However, the role of GB character in solute segregation and thermal stability of NC metals remains poorly understood. Herein, we employ high resolution microscopy techniques, atomistic simulations, and theoretical analysis to investigate and characterize the impact of GB character on segregation behavior and thermal stability in a model NC Pt-Au alloy. High resolution electron microscopy along with X-ray energy dispersive spectroscopy and automated crystallographic orientation mapping is used to obtain spatially correlated Pt crystal orientation, GB misorientation, and Au solute concentration data. Atomistic simulations of polycrystalline Pt-Au systems are used to reveal the plethora of GB segregation profiles as a function of GB misorientation and the corresponding impact on grain growth processes. With the aid of theoretical models of interface segregation, the experimental data for GB concentration profiles are used to extract GB segregation energies, which are then used to elucidate the impact of GB character on solute drag effects. Our results highlight the paramount role of GB character in solute segregation behavior. In broad terms, our approach provides future avenues to employ GB segregation as a microstructure design strategy to develop NC metallic alloys with tailored microstructures.A polymer in a turbulent flow undergoes the coil-stretch transition when the Weissenberg number, i.e. the product of the Lyapunov exponent of the flow and the relaxation time of the polymer, surpasses a critical value. The effect of internal friction on the transition is studied by means of Brownian dynamics simulations of the elastic dumbbell model in a homogeneous and isotropic, incompressible, turbulent flow and analytical calculations for a stochastic velocity gradient. The results are explained by adapting the large deviations theory of Balkovsky et al. [Phys. Rev. Lett., 2000, 84, 4765] to an elastic dumbbell with internal viscosity. In turbulent flows, a distinctive feature of the probability distribution of polymer extensions is its power-law behaviour for extensions greater than the equilibrium length and smaller than the contour length. selleck inhibitor It is shown that although internal friction does not modify the critical Weissenberg number for the coil-stretch transition, it makes the slope of the probability distribution of the extension steeper, thus rendering the transition sharper. Internal friction therefore provides a possible explanation for the steepness of the distribution of polymer extensions observed in experiments at large Weissenberg numbers.This work describes the synthesis of poly(butylene adipate) (PBAd), by melt polycondensation, poly(l-lactic acid) (PLLA), by ring opening polymerization, and the new block copolymer PLLA/PBAd in ratios 90/10, 95/5, 75/25 and 50/50. Due to the biocompatibility and low toxicity of neat PBAd and PLLA, these copolymers are suitable to be used in biomedical applications. The 1H and 13C nuclear magnetic resonance spectroscopy techniques were employed for structural characterization. The thermal transitions, with an emphasis on crystallization, were assessed by differential scanning calorimetry, supplemented by X-ray diffraction and polarized optical microscopy. Molecular mobility studies were conducted using two advanced techniques, broadband dielectric spectroscopy and thermally stimulated depolarization currents. The results from the structural techniques, in combination with each other, provided proof of the presence of PLLA and PBAd blocks and, moreover, the successful copolymer synthesis. The overall data showed that the different co-polymer compositions result directly in severe changes in the polymer crystal distribution and, indirectly, the formation of PBAd micro/nano domains surrounded by PLLA.
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