Papers by Keyword: Synthesis

Abstract: The aim of the present work is to study the influence of the precipitation temperature in the synthesis of nanohydroxyapatite (n-HAp) on the properties of the resulting n-HAp powder for the fabrication of highly porous scaffolds for bone tissue engineering. The n-HAp powder was obtained by a wet precipitation technique starting from calcium nitrate tetrahydrate (Ca (NO₃)₂*4H₂O) and phosphoric acid (H₃PO₄) at different temperatures: 10°C, 37°C and 50°C. Highly porous scaffolds were fabricated using the three different powders by the sponge replica method and sintering at 1300°C. Combined X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses on powders indicated that on increasing the precipitation temperature the formation of pure n-HAp is accelerated, without significant changes in particles morphology and size. Scaffolds characterized by high porosity (89%) and good compressive strength (0.53 MPa for n-HAp prepared at 37°C) were obtained. XRD analyses on sintered n-HAp confirmed the thermal stability of the material. Therefore, the as-synthesized n-HAp powder can be successfully used for the fabrication of highly porous scaffolds as bone substitutes.

Abstract: Cu/graphene nanosheets composites were fabricated at 800°C by the hot-pressing method using Cu and graphene as initial materials. Graphene content was 1 wt. %-5 wt. %. The fracture morphology and physical properties of the composites were investigated. It was found that the relative density increased with the increment of graphene content from 1 wt% to 5 wt. % with reaching its highest level (96.68%) at 5wt. %. The composites have the anisotropic property which is vertical to the direction of pressure is higher than parallel to the direction of pressure. With the increasing of graphene content, the thermal conductivity property and the electronic conductivity decrease first and then increase with the minimum thermal conductivity and electric conductivity at 3wt%~4wt%.

Abstract: Waterborne side-chain fluorinated polyurethanes were prepared from fluorine-containing polyether polyol, N210, isophorone diisocyanate (IPDI) as main materials through self-emulsified method. The factors on FWPU, including the particle size and distribution, solid content, the acid and alkali resistant properties of emulsion film, were investigated. The results indicated that the particle size of fluoronated polyurethane dispersion was small, and dispersion had good stability. The emulsion film had better chemical resistant properties.

Abstract: A novel binuclear ruthenium vinyl complexes with dithienylethene unit II [RuCl (CO)(PMe₃)₃]₂(μ-CH=CH-DTE-CH=CH) has been synthesized and characterized by elemental analysis and NMR spectra. Meanwhile, the crystal of II was obtained and determined by X-ray single-crystal diffraction.

Abstract: We report on the synthesis and electrochemical properties of multi-walled carbon nanotube (MWNT)/polyaniline (PANI) nanocomposites. The MWNT/PANI composite was prepared through electrochemical polymerization and is confirmed by ultraviolet-visible spectroscopy (UV-vis) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The MWNT/PANI nanocomposites show a specific capacitance value as high as 463 F/g.

Abstract: 2, 2'- methylene-bis (4,6-di-tert-butyl-phenyl) phosphate sodium (NA-11), a nucleator of polypropylene (PP) was high-efficiently prepared with homemade 2,2-methylene-bis (4,6-di-tert-butyl-phenyl) phosphorus oxychloride as raw materials by means of hydrolysis and neutralization, and the overall yield of the product was 95.9 %. The synthesized product was characterized by Fourier Transform Infrared spectroscopy (FTIR), thermogravimetry (TG), elemental analysis and ³¹P-NMR. Polypropylene was modified with the synthesized product as a nucleating agent. The results showed that the tensile strength, flexural strength, and the flexural modulus of composites increased by 12.1%, 30.2%, 41.0% respectively when the synthesized product is 0.1wt%, and the haze decreased form 42.9% to 17.3%.

Abstract: The complex of di-(2-methyl-8-hydroxyquinoline) zinc (Zn (2-mq)₂) was synthesized. The complex was characterized by elemental analysis, ¹HNMR, ¹³CNMR, infrared, UV-vis, XRD and molar conductivity. The zinc (II) ion was found to coordinate to the oxygen atom of phenolic hydroxyl and nitrogen atoms of 2-methyl-8-hydroxyquinoline and the complex conformes to 1:2 metal-to-ligand stoichiometry. The fluorescence properties of the complex in solid and solution were studied. The complex exhibits yellow light under the excitation of UV light. The solvent factors influencing the fluorescent intensity are discussed.

Abstract: Solketal is widely used as organic solvent, plasticizer and pharmaceutical intermediates. A synthetic technique for solketal, which is characteristic of being catalyzed by sulfonic acid resin, was developed. Experimental results showed that the suitable synthetic conditions for solketal were as follows: mass ratio of two kinds of raw materials, glycerol to acetone, is 1:20, catalyst DT-851 sulfonic acid resin dosage is 5% (wt, calculated by glycerol), reaction temperature is 58 °C and reaction time is 2 h. The product solketals yield is 95% with purity above 99% under the optimal conditions. This new technique features mild reaction conditions, easy purification, high yield, and less pollution and therefore, it is a kind of clean and green production technique.

Abstract: Pyrrolo [1,2-a] pyrazine possessed widely bioactivities due to its particular structure. In this work, three pyrrolo [1,2-a] pyrazines derivatives were synthesized from the 2-bromo-5-methoxypyrazine and propargyl amines or ethers through the Pd-catalyzed intermolecular cycloisomerization strategy. Their structures were characterized by NMR, IR, EI-MS and elemental analysis, and all of them exhibited moderate in vitro anti-inflammatory effects with the inhibitions of 43-59% against IL-6 at 50 μM. The compound 3c revealed relatively good anti-inflammatory activities. The bioactive pyrrolo [1,2-a] pyrazines might be potentially used as anti-inflammatory agents.

Abstract: Hydroxylchalcone are known to act on various physiological targets. In this study, a series of nine hydroxychalcones were synthesized via the aldol condensation with the aim of obtaining bioactive small molecules. Their structures were characterized by NMR spectra. The anti-breast cancer activity evaluation indicated the monohydroxychalcones exhibited the better anti-proliferative effect than dihydroxylchalcones against MDA-MB-231 cells, and the compound 3b showed the best anti-breast cancer activities at 18 μM. The bioactive compounds might be used to develop as potential anti-breast cancer agents.