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A thermosensitive chitosan-based hydrogel for controlled release of insulin
Ting-Ting GAO,Ming KONG,Xiao-Jie CHENG,Gui-Xue XIA,Yuan-Yuan GAO,Xi-Guang CHEN,Dong Su CHA,Hyun Jin PARK
Frontiers of Materials Science. 2014, 8 (2 ): 142-149.
https://doi.org/10.1007/s11706-014-0247-7
Present study aims at synthesizing a thermosensitive hydrogel for controlled release of insulin. According to a modified method, hydroxybutyl chitosan (HBC) hydrogel possessed thermal sensitivity is prepared which can form hydrogel at over 25°C. The HBC hydrogel is non-cytotoxic to mice fibroblasts cells (L929). Insulin is 100% entrapped in the hydrogel, 38% of which is released in vitro from the concentration of 5% hydrogel after 48 h, whereas by enzymolysis with lysozyme, 80% of the total insulin is released after 48 h. This study suggests that HBC hydrogel could be utilized for controlled release of insulin in a non-invasive manner.
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Green synthesis of metal/C and metal oxide/C films by using natural membrane as support
Cheng-Zhen WEI,Hai-Feng MA,Feng GAO
Frontiers of Materials Science. 2014, 8 (2 ): 150-156.
https://doi.org/10.1007/s11706-014-0248-6
A protocol aiming at making use of the huge amount of naturally existing wastes such as defoliation, pericarp and egg shell for nanostructured composite materials was proposed. In this study, a green synthetic route using naturally existing membrane as support was developed for the synthesis of nanostructured and porous metal- or metal oxide-carbon composite films. Different metallic ions (Co2+ , Ni2+ , Fe3+ , Mn2+ or Cu2+ ) can be easily adsorbed onto egg membranes and the followed calcination process results in the formation of Co/C, Ni/C, Fe3 O4 /C, MnO/C or Cu/Cu2 O/CuO/C composite films. The electrochemical studies demonstrate that such composite films would have potential applications in energy fields. This method would provide a general green concept for chemical synthesis and be beneficial to the global sustainable future.
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Origin of high mechanical quality factor in CuO-doped (K, Na)NbO3 -based ceramics
Wen-Feng LIANG,Ding-Quan XIAO,Jia-Gang WU,Wen-Juan WU,Jian-Guo ZHU
Frontiers of Materials Science. 2014, 8 (2 ): 165-175.
https://doi.org/10.1007/s11706-014-0245-9
The origin of a high mechanical quality in CuO-doped (K, Na)NbO3 -based ceramics is addressed by considering the correlations between the lattice positions of Cu ions and the hardening effect in K0.48 Na0.52+x NbO3 --0.01CuO ceramics. The Cu ions simultaneously occupy K/Na and Nb sites of these ceramics with x = 0 and 0.02, only occupy the K/Na site of the ceramics with x = --0.02, and mostly form a secondary phase of the ceramics with x = --0.05. The Cu ions lead to the hardening of ceramics with an increase of E C and Q m by only occupying the K/Na site, together with the formation of double hysteresis loops in un-poled compositions. A defect model is proposed to illuminate the origin of a high Q m value, that is, the domain stabilization is dominated by the content of relatively mobile O2-- ions in the ceramics, which has a weak bonding with CuK/Na defects.
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Phase field crystal simulation of grain boundary movement and dislocation reaction
Ying-Jun GAO,Qian-Qian DENG,Si-Long QUAN,Wen-Quan ZHOU,Chuang-Gao HUANG
Frontiers of Materials Science. 2014, 8 (2 ): 176-184.
https://doi.org/10.1007/s11706-014-0229-9
The phase field crystal (PFC) model is used to simulate the premelting dislocation movement of the symmetric tilt grain boundary (STGB) under strain action when the system temperature is at far from the melting point and close to the melting point, respectively. The results show a local premelting occurs surrounding the dislocations as the premelting temperature is approached to from below temperature. The premelting dislocations of the STGB can glide under strain action, and the premelting region is a companion for dislocation gliding. The process of STGB decay is very similar at the two high temperature conditions. As premelting presents, it diminishes the gliding resistance for the dislocations and leads to a faster movement of dislocations, and also brings about more energy reduction of the system during the decay process of STGB. In spite of applying strain to these premelting samples in whole decay processes of STGB, the premelting dislocation region does not obviously develop and extend. This indicates that the external strain action does not promote the premelting at the high temperature, and cannot induce more premelting dislocation, which can be owed to the premelting phase around the dislocation exhibit fluid-like properties and to the premelting dislocation easily gliding and relaxing the strain energy; this is in agreement with the results of experiments and molecular dynamics.
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Simulation of epitaxial growth on convex substrate using phase field crystal method
Ying-Jun GAO,Li-Lin HUANG,Qian-Qian DENG,Kui LIN,Chuang-Gao HUANG
Frontiers of Materials Science. 2014, 8 (2 ): 185-192.
https://doi.org/10.1007/s11706-014-0243-y
Phase field crystal (PFC) model is employed to simulate the process of growth of epitaxial layer on plane-convex substrate with a lattice mismatch and a small inclination angle. The variation of the systematic free energy, the total atomic number of the epitaxial layer, and the effect of the curvature and the angle of the substrate are analyzed. The results show that when the surface of the substrate is plane, the free energy increases with the increase of the substrate inclination angle, and also the total atomic number of the epitaxial layer increases; while the surface of the substrate is convex, the free energy decreases with the increase of substrate angle and so also the total atomic number of the epitaxial layer decrease. This is the reason that the frontier of surface of epitaxial layer changes from the step bunching to the hill-and-valley facet structure with the increasing of the inclination angle of convex substrate. These results are in good agreement with the other method results.
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