Synthesis and characterization of novel elastomeric poly(D,L-lactide urethane) maleate composites for bone tissue engineering

Here, we report the synthesis and characterization of a novel 4-arm poly(lactic acid urethane)-maleate (4PLAUMA) elastomer and its composites with nano-hydroxyapatite (nHA) as potential weight-bearing composite. The 4PLAUMA/nHA ratios of the composites were 1:3, 2:5, 1:2 and 1:1. FTIR and NMR characterization showed urethane and maleate units integrated into the PLA matrix. Energy dispersion and Auger electron spectroscopy confirmed homogeneous distribution of nHA in the polymer matrix. Maximum moduli and strength of the composites of 4PLAUMA/nHA, respectively, are 1973.31 ± 298.53 MPa and 78.10 ± 3.82 MPa for compression, 3630.46 ± 528.32 MPa and 6.23 ± 1.44 MPa for tension, 1810.42 ± 86.10 MPa and 13.00 ± 0.72 for bending, and 282.46 ± 24.91 MPa and 5.20 ± 0.85 MPa for torsion. The maximum tensile strains of the polymer and composites are in the range of 5–93%, and their maximum torsional strains vary from 0.26 to 0.90. The composites exhibited very slow degradation rates in aqueous solution, from approximately 50% mass remaining for the pure polymer to 75% mass remaining for composites with high nHA contents, after a period of 8 weeks. Increase in ceramic content increased mechanical properties, but decreased maximum strain, degradation rate, and swelling of the composites. Human bone marrow stem cells and human endothelial cells adhered and proliferated on 4PLAUMA films and degradation products of the composites showed little-to-no toxicity. These results demonstrate that novel 4-arm poly(lactic acid urethane)-maleate (4PLAUMA) elastomer and its nHA composites may have potential applications in regenerative medicine.     

Li-ion-conductive Li2TiO3-coated Li[Li0.2Mn0.51Ni0.19Co0.1]O2 for high-performance cathode material in lithium-ion battery

Journal of Solid State Electrochemistry - Li2TiO3 is used as a novel coating material to modify Li(Li0.2Mn0.51Ni0.19Co0.1)O2 electrode to enhance the electrochemical performance of the host...     

聚丙烯及增韧剂对复合材料熔接痕强度的影响

研究了聚丙烯基体的熔体粘度(以熔体流动速率表征)、增韧剂POE的粘度(以门尼粘度表征)、增韧剂POE的含量等因素对聚丙烯复合材料熔接痕强度的影响。结果表明:聚丙烯基体/增韧剂的粘度比越小,聚丙烯复合材料的熔接痕强度越高,即聚丙烯粘度越小、增韧剂粘度越大,整个复合材料的熔接痕强度越高;增韧剂POE的含量越大复合材料的熔接痕强度越小。     

Local discrimination scheme for some unitary operations

It has been shown that for two different multipartite unitary operations U_1 and U_2, when tr(U_1~?U_2) = 0, they can always be perfectly distinguished by local operations and classical communication in the single-run scenario. However, how to find the detailed scheme to complete the local discrimination is still a fascinating problem. In this paper, aiming at some U_1 and U_2 acting on the bipartite and tripartite space respectively, especially for U_1~?U_2 locally unitary equivalent to the high dimensional X-type hermitian unitary matrix V with trV = 0, we put forward the explicit local distinguishing schemes in the single-run scenario.     

Co-precipitation synthesis of precursor with lactic acid acting as chelating agent and the electrochemical properties of LiNi0.5Co0.2Mn0.3O2 cathode materials for lithium-ion battery

Journal of Solid State Electrochemistry - Hydroxide precursor Ni0.5Co0.2Mn0.3(OH)2 was successfully prepared by co-precipitation using lactic acid as the environment-friendly chelating agent. And...