Multilayer of TiO2 and TiO2:SiO2 thin films were grown on a glass substrate by sol?Cgel processes, followed by high temperature treatment at 500?°C. The fine grained TiO2 films controlled by SiO2 dopant showed very good wear resistance and endurance life. Energy dispersive X-ray spectroscopy was used to indicate the elements in the films. X-ray diffraction analyses indicated that TiO2 and TiO2:SiO2 film contain only anatase phase. The morphologies of the original and worn surfaces of the samples were analyzed by means of scanning tunneling microscope and scanning electron microscopy. The tribological properties of TiO2 and TiO2:SiO2 thin films sliding against AISI52100 steel pin were evaluated on a pin on disk friction and wear tester. The results showed that 25-layer TiO2:SiO2 films are superior in reducing friction and resisting wear compared with the glass substrate. 相似文献
It is shown that the obtained hardness and electrophilicity values of the short length oligomers for a heterocyclic conductive polymer from density functional theory method are quadraticly correlated to those obtained from semiempirical method. Therefore these quantities for all oligomers (up to 15 repeating units) are predicted using the obtained quadratic relations. Both of these predicted quantities for different oligomers are fitted to a new exponential model (Y = Y∞ ed/n) to estimate the electronic properties for the considered conjugated polymers. The calculated band gaps from this model show better agreement with the reported experimental data than those predicted by the previous models. Because of a wide range of variations, the electrophilicity could be a better index for investigating the doping effect in polymers than the hardness.
The single-wing extension of the bowl-shaped tribenzotriquinacene (TBTQ) framework with polycondensed aromatic hydrocarbon units has been reported. In the course of a Scholl reaction, one of the three-dimensional bays of the TBTQ core has been bridged by a PAH unit to generate a seven-membered ring within the merged TBTQ-(hexa-peri-hexabenzocoronene) scaffold. 相似文献
The natural bond orbital (NBO) analysis, nucleus independent chemical shift (NICS), and 14N NQR parameters of the most stable tautomers of adenine in the gas phase were predicted using density functional theory method. The NBO analysis revealed that the resonance interaction between lone pair of the nitrogen atom and empty non‐Lewis NBO increases with increasing the p character of the nitrogen lone pair. The present investigation indicated the π clouds in both the considered heterocyclic rings containing six electrons, and these tautomers has the aromatic character. The NICS study utilizing the gauge‐invariant atomic orbital method showed that there are diatropic currents in the heterocyclic rings of the tautomers, so we determined the order of overall aromaticity of these tautomers. The results of NQR parameter calculations showed three parameters are effective on nuclear quadrupole coupling constant; the p character value of lone pair electrons of nitrogens, and the related occupancies and whenever, the lone pair electrons of nitrogens participate in the formation of chemical bond and/or π system of the ring, the qzz and consequently its χ decreases. 相似文献
We have synthesized ferromagnetic nanoparticles with an imprinted polymer coating that is capable of adsorbing and extracting uranyl ions. The adsorbent was characterized using infrared spectroscopy, elemental analysis, X-ray powder diffraction analysis, and scanning electron microscopy. The effects of sample pH, sample volume, weight of the adsorbent, contact time and of other ions have been investigated in the batch extraction mode. The performance of the material was compared to that of particles coated with a non-imprinted polymer. The adsorbent containing the imprinted coating displays higher sorption capacity and better selectivity to uranyl ions. The method was successfully applied to the determination of uranyl ions in water samples.
Figure
Magnetic separation of uranyl ions from aqueous solution using a new uranyl-imprinted material prepared by surface modification of silica coated magnetic nanoparticles 相似文献
A well crystalline nickel?Caluminum?Czirconium ternary-layered double hydroxide was firstly synthesized and applied as a solid-phase extraction sorbent for the separation of trace levels of chloride ions from aqueous solutions. An indirect method was used for monitoring of the extracted chloride ions. For this purpose, the extracted chloride ions were passed through a reaction column containing silver chloranilate powder and the analyte was precipitated as silver chloride. The concentration of chloranilate ions released from the reaction column, which corresponds to the chloride ions concentration, was then determined spectrophotometrically at 530?nm. The effect of several parameters, such as pH, sample loading flow rate, elution conditions, amount of nano-sorbent, sample volume and effect of potential interfering ions on the recovery was investigated. In the optimum experimental conditions, the limit of detection (3?s) and enrichment factor were 0.12 and 40???g?mL?1, respectively. The calibration graph using the pre-concentration system was linear in the range of 0.25?C3.00???g?mL?1 with a correlation coefficient of 0.997. The validation of the presented method was checked by the analysis of two certified reference materials. The optimized method was successfully applied to the determination of chloride ions in waters, food and biological samples. 相似文献
A concise and facile synthesis of a new class of P,O-heterocycles is described. Knoevenagel condensation reaction of a salicylaldehyde and a cyclohexane-1,3-dione forms an α,β-unsaturated intermediate, which undergoes nucleophilic addition of a trialkyl phosphite under solvent-free conditions to afford the title compounds in good to excellent yields. 相似文献
A one-pot three-component synthesis of 6-aryl-8H-dibenzo[d,h][1,3,7,2]dioxazaborecin-8-ones is described. A mixture of 2-aminobenzoic acid, 2-hydroxybenzaldehyde, and arylboronic acid undergo a 1:1:1 addition reaction in CCl4 under microwave irradiation to produce bridgehead bicyclo[4.4.0]boron heterocycles in excellent yields. 相似文献
Triphenylphosphine ditriflate (TPPD) was found to be an efficient promoter for the Friedel-Crafts benzylation of arenes with benzyl alcohols in CH2Cl2 at room temperature. The good yields, the 1:1 molar ratio of arene and benzyl alcohol, the benzylation of chlorobenzene as a nonactivated aromatic compound at room temperature, and no by-product formation are the main advantages of this procedure. 相似文献
A simple, efficient one-step route to polystyrene-supported trialkylphosphine ligands is reported. These polymer-supported alkyl phosphine ligands proved to be highly active for Suzuki-Miyaura reactions and in alkoxycarbonylation reactions. The palladium loaded polymer-supported catalysts can be recycled several times with only minimal loss of catalyst activity. 相似文献