Dendrimer, a new class of hyper-branched polymer with predetermined molecular weight, is being received much attention in nano biomedical applications such as anticancer drug delivery, gene therapy, disease diagnosis and etc. In this study, polyamidoamine (PAMAM)-based dendrimer generation 3.0 (G 3.0) was synthesized and subsequently pegylated. Obtained results showed that pegylation degree of the dendrimer was around 31% for its external amine groups. TEM image of the pegylated dendrimer exhibited spherical shape and nano sizes ranging from 30 to 40 nm. The fluorouracil (5-FU)-loaded pegylated dendrimer showed a slow release profile of the drug. In vitro study, at the primary screening concentration of 100 microg/mL, the PAMAM dendrimer presented higher toxicity in MCF-7 cells as compared to its pegylated counterpart. Meanwhile, the (5-FU)-loaded pegylated dendrimer exhibited the antiproliferative activity against the cell line with the IC50 of 9.92 +/- 0.19 microg/mL. In vivo tumor xenograft study, we succeeded in generating MCF-7 cells-derived cancer tumors on mice that was well-confirmed by using flow cytometer assay. The 5-FU encapsulated pegylated dendrimer exhibited a significant decrement in volume of the tumors which was generated by MCF-7 cancer cells.
In this study, magnetic snail shell (MSS) prepared by impregnating of iron oxide onto snail shell (SS) powder was used for removing Cr(VI) from aqueous solution. Among different mass ratios of Fe/SS powder studied, the MSS25 produced at a ratio of 25% achieved the highest Cr(VI) adsorption capacity. Batch adsorption experiments were conducted to investigate the adsorption isotherm, kinetics and mechanism of Cr(VI) onto MSS25. The results illustrated that adsorption of Cr(VI) onto MSS25 reached equilibrium after 150 min at pH 3. The adsorption kinetics could be well described by the pseudo-second order model (R 2 =0.986). The Langmuir model (R 2 =0.971) was the best-fitting model that described the adsorption isotherm of Cr(VI) onto MSS25. The maximum adsorption capacity was 46.08 mg Cr(VI) per gram of MSS25. Ion-exchange, electrostatic attraction and adsorption-coupled reduction were determined as the main adsorption mechanisms of Cr(VI) onto MSS25. The high percentages of CaCO3 and Fe3O4 found in the MSS25 structure made a significant contribution to the Cr(VI) adsorption process.
Star-shaped poly(methyl acrylate) (PMA) was synthesized using tri(2-bromopropionate) glyceride as the initiator and methyl acrylate as the monomer via atom transfer radical polymerization (ATRP). The structures of tri(2-bromopropionate) glyceride and PMA were characterized by IR, GC-MS, 1 H NMR, and 13 C NMR. The reinforcing effects of this star-shaped PMA on polyvinylchloride (PVC) in various PMA/PVC blends were evaluated. The results indicated that a blend containing 1% star-shaped PMA exhibits an 18% increase in the elastic modulus and a 10% increase in tensile strength compared to PVC. Moreover, the impact resistance of the blend was 30% higher than that for PVC. The blend also exhibited high thermal stability. SEM images showed that the star-shaped PMA and PVC are highly compatible when blended, which causes the enhanced elasticity of the blend.
Aeroelasticity on airplane wing has a significant impact on the efficiency and the safety of a flight. Therefore, the study of aeroelasticity problems is a great attention in wing design process. To analyze this, three primary subjects of aeroelastic phenomena that the examination has to focus on, which are wingtip oscillation amplitude, flutter frequency and critical flutter velocity of the wing. [1] As these subjects are highly dependent on structures and materials of the wings, therefore, the aim of this paper is to introduce a structural calculation which is the combination of three experimental models and the infinite element method. Supercritical is chosen as the sample airfoils of the simulation. The model wings are made from different materials and size in order to create varied wing structures, thereby a comprehensive analysis is accomplished and the flutter velocity is also restricted to appropriate values within the working range of experiment devices. Simultaneously, Infinite element method using ANSYS software to simulate the phenomena on the same model wings is also conducted as a verification for the precision of the experimental models. In conclusion, obtained results from the structural calculation have a high applicability in the preliminary design stage of airplane wings, by making comparisons between two or more chosen airfoils to conclude which is the better one in term of wing sustainability and aeroelasticity resistance.
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