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Three compounds: 4-vinylpyridine-4-(N,N-diphenylamino)benzene(PPAB), Tris[4- (4-Pyridylethenyl)phenyl]amine (TPPA), 4-(N,N-diphenylamine)benzene -vinyl -1-methyl- pyridinium iodide(PBPI), were synthesized and characterized. The absorption and one-photon fluorescence properties have been investigated . Three-photon upconversion fluorescence spectra of these molecules were measured using a femtosecond Ti:sapphire. Large optical power limiting has also been demonstrated for the three compounds. Their three-photon absorption coefficients obtained by nonlinear transmission method are 1.91×10-79cm6s2, 3.46×10-79cm6s2, 3.64×10-79cm6s2 , respectively.
Using B3LYP/6-311+G** method, the initial geometrical structures of boron-carbon clusters C2+nB10-n (n=0~10) containing double planar pentacoordinate carbon (ppC) were optimized and their vibrational frequencies were calculated. Present results showed that C2+nB10-n (n=0~2) clusters are stable, in which the Wiberg bond index (WBI) of ppC—B bonds are between 0.511 and 0.909 and the WBIs of ppC—C are 0.2254 (n=1) and 0.8586 (n=2), as well as the WBIs of ppC are 3.778 and 3.879, i.e. the three molecules include double ppCs and ppCs obey octal rule; the C2+nB10-n (n=3~6) clusters with the lowest energy contain one ppC, while the lowest energy C2+nB10-n (n>6) clusters have no ppC. In addition, only the C2+nB10-n (n=0~2) clusters do not include dangling bonds, and the numbers of ( electron in the C2+nB10-n (n=0~2) clusters are 6, 7 and 8, respectively. Calculated NICS(0) values indicate that the strong aromaticity mainly locates at the centers of the three-membered rings. The vertical transition energies of C2+nB10-n (n=0~2) clusters are 1.91, 0.56 and 3.12 eV.
The isomeric structures and energetics of two Sn, Pb-containing penta-atomic planar tetracoordinate carbon molecules [CAl3X] and [CAl3X]- (X=Sn, Pb) (with 17 and 18 valence electrons, respectively) were studied by using the B3LYP method combined with the mixed basis set 6-311+G(d)&LANl2dz for the first time. The results were compared with the previously reported [CAl3X] and [CAl3X]- (X=Si, Ge). It was shown that the isomer int1 with the planar tetracoordinate carbon structure was the global minimum point. Relative to the 17e system [CAl3X], achieving an additional electron to form the 18e system [CAl3X]- int1 becomes thermodynamically more stable. The present work would enrich the penta-atomic planar tetracoordinate carbon chemistry.
Using poly(acrylamide-co-methacrylic acid) copolymer microgels prepared by a reverse suspension polymerization technique as templates, poly(acrylamide-co-methacrylic acid)/tungsten [P(AM-co- MAA)/W] composite microspheres with core-shell structures were fabricated by centrifugal deposition of tungsten powder on the polymer template surface. Then P(AM-co-MAA)/W/UF(urea-formaldehyde) resin composite microspheres with multi-layer core-shell structures were produced via polycondensation between formaldehyde and urea conducted at the interface between the P(AM-co-MAA)/W template and oil/water phase. The prepared composite microspheres were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR) and thermogravimetric analysis (TGA) techniques. It was demonstrated that the amount of UF resin coated and surface morphologies of P(AM-co- MAA)/W/UF composite microspheres could be controlled by varying the concentrations of formaldehyde and urea solutions and the molar ratio of formaldehyde to urea. The electric conductivity of prepared composite microspheres significantly decreased from 1.9×10-3 to 0.9×10-8 S•m-1, before and after coating of urea-formaldehyde resin layer on the surface of P(AM-co-MAA)/W composite microspheres. The prepared composite microspheres with the three-layer core-shell structures are of the quite full and dense coating layer, and its conductivity is nearly close to the insulating materials. All these characteristics of the composite microspheres containing tungsten materials would establish a better foundation for the application as the anti-radiation coating materials of the electronic component.
1-(3,4-Dimethoxyphenyl)ethanol (DMPE) was synthesized and used as the model of lignin. Kinetics of the reaction of DMPE with hydrogen peroxide catalyzed by three copper(II) complexes was studied in phosphoric acid buffer solution at 40 ℃. A kinetic model of catalytic oxidation of DMPE was suggested, and the kinetic parameters k2 and Km under different conditions were obtained. The catalytic efficiency of the copper(II) complexes increased with increasing pH. The complex with the electron conjugated ligand showed the best catalytic activity on the oxidation reaction. A possible catalytic mechanism of the oxidation of DMPE was proposed and discussed in detail.
TiO2 and CdSe nanorods were prepared by a hydrothermal method. The photoelectrochemical properties of TiO2/CdSe composite film and TiO2/CdSe/PMeT film were investigated. The experiment results showed that the incident photon to current conversion efficiency (IPCE) of TiO2/CdSe/PMeT was obviously increased in comparison to that of TiO2/CdSe composite film. The experiment results showed that the p-n heterojunction existed in the TiO2/CdSe/PMeT nanostructure film, which favored the separation of electron-hole pairs generated by photoexcitation. The IPCE value of TiO2/CdSe/PMeT film was 56% at -0.2 V, and the incident light wavelength of 370 nm. The hybrid solar cell was fabricated with TiO2/CdSe nanostructure composite film and poly(3-methylthiophene) (PMeT). The conversion efficiency of the hybrid solar cell was 0.08%, short current 0.61 mA/cm2, open voltage 0.4 V, fill factor 0.33, under irradiation of 100 mW/cm2 white light from a Xe lamp.
The geometries and binding energies of the complexes between C4H4Y (Y=O, S, Se) and BX3 (X=H, F, Cl) have been calculated at the density function theory B3LYP and the second-order M?ller-Plesset theory MP2(full) levels. The vibration and natural bond orbital analyses were carried out, which indicate that the 18 conformers obtained include π-p interaction (the BX3 locating exactly above the C=C double bond) and n-p interaction (the boron atom directly combining to O, S or Se). The stabilities of C4H4Y-BH3 complexes are in the order of n-p>π-p. The stabilities of C4H4Y-BF3 and C4H4Y-BCl3 complexes with n-p interaction are relative to the π-p type complexes. The calculated results show that charge transfers, frequency shifts and change of geometries are relative to the stabilities of the complexes in the forming process.
A stage-like appearance occurred in the first exponential phase of several bacteria's thermogenic curves determined by a microcalorimetry ampoule method, and the growth rate constants of these stages were very different, which has not been found before in a stop-flow method and disturbs the precise antibacterial activity evaluation. In order to find the possible reasons, the growth of E. coli under different environmental atmosphere as well as the condition similar to the stop-flow method was determined and analyzed. The environmental atmosphere is mainly responsible for this variation. A criterion was recommended for the selection of growth rate constant under various atmosphere when determined by ampoule method.
The competition interaction of two active components of Chinese traditional herb, ferulic acid (FA) and paeonol (PAE), with immobilized human serum albumin (HSA) on chromatographic support under human physiological condition (pH 7.4) has been investigated by high-performance affinity chromatography (HPAC). Based upon the assumption that there were several independent types of binding sites on an HSA molecule for each drug, the interaction of immobilized HSA with FA and PAE was investigated by frontal analysis and competition displacement analysis. The results showed that there was only a single binding site in the HSA molecule for FA and PAE. As FA and PAE coexisted, they had a direct competition for the indole site (site II) of HSA molecule. According to the thermodynamic parameters, the main force between HSA and FA or PAE was deduced to be hydrogen bonding. The conclusion that both PAE and FA competed with each other for the same binding site of HSA molecule could be used to explain some phenomena in the Chinese medicine clinic, in which the clinical efficacy of each drug can be improved by utilizing the compatibility of Chinese traditional medicine.
A dinuclear Eu(III) complex [HN(CH3CH2)3]2[Eu2(bdb)4]•CH3CH2OH [H2bdb=4,4'-bis (4",4",4"-trifluoro-1",3"-dioxobutyl)-o-terphenyl] was synthesized. The complex emits bright red luminescence, characteristic of the 5D0 → 7FJ (J=0~4) emission peaks of Eu3+ under near UV irradiation. The luminescence lifetime of the emitting 5D0 level of the complex is 704 μs. The decay curve can be fit with a single exponential model. Monitored at 614 nm, excitation wavelength is located in the range of 250~420 nm. Excitation intensity of the complex is strong enough at 395 nm and the complex can be well excited by the 395 nm emission light of InGaN chip. The investigation of the temperature dependence of PL intensity for the Eu(III) complex shows that the complex can keep up with good emission intensity as the temperature rises to 200 ℃. The thermogravimetric analyses curve for complex shows the complex is up to 260 ℃. The luminescence properties and thermostability meet the requirements of fabrication of LED device. Bright red conversion light-emitting diode (LED) device was fabricated by coating complex onto 395 nm InGaN chip. When the mass ratio of the europium complex to the silicone is 1∶20, the LED CIE chromaticity coordinates is x=0.61, y=0.31. The luminescence efficiency of device is 3.64 lm/W under 20 mA forward bias. White conversion LED was fabricated by coating this europium complex and bis(2-(2'-hydroxyphenyl)benzothiazolate)zinc [Zn(btz)2] onto 395 nm InGaN chip. The appropriate mass ratio to obtain white light of the europium complex, [Zn(btz)2] and the silicone is 1∶1∶25, the LED CIE(Commission International d'Eclairage) chromaticity coordinates is x=0.32, y=0.32, Tc=6026 K, Ra=81 under 20 mA forward bias. The luminescence efficiency of device is 1.26 lm/W. The results indicate that the europium complex can act as red component in the fabrication of white LEDs.
The electrochemical measurement and surface analysis methods were carried out to investigate the corrosion behavior of steel A3 in Thiobacillus ferrooxidans, streptomyces and T. f-streptomyces mixed colony systems. Results showed that asymmetric biofilms adhered on the surface of steel A3 after 7 days of exposure in different corrosive systems; pitting corrosion occurred on the surface of steel A3 after 7 days of exposure in T. f and streptomyce solutions, but an even corrosion appeared in T. f-streptomyces mixed colony solution; weight loss in the mixed colony system was between those caused by each individual microorganisms; the electrochemical impedance spectroscopy results indicated that the impedance value of steel A3 in the mixed colony system was the medium of those in T. f and streptomyces system. Above results revealed that the most serious corrosion occurred in the streptomyces system, secondly for the T. f-streptomyces mixed colony solution, and corrosiveness of the T. f solution was the lightest to steel A3.
A magnetic field controlled and disposable amperometric immunosensor was fabricated for determination of chloramphenicol (CAP) by carbon nanotube (CNT)/ferrocene(Fc)/Nafion-membrane coated on the screen-printed carbon electrodes (SPCE) and then GMP [Fe3O4(core)/Au(shell)] composite nanoparticle coated chloramphenicol-bovine serum albumin (CAP-BSA) was absorbed on it through external magnetic field. Scanning electron micrography (SEM) and X-ray fluorescence spectrometry (XRFS) were employed to characterize the construction process of the immunosensor. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study its electrochemical properties. The content of CAP was determined with competitive immunoassay. When CAP of different concentration was added in 25 μL of pH=6.0 phosphate buffer solution (PBS) containing 100 ng•mL-1 anti-CAP, the percentage of cathodic peak DPV current increase ratio (CI%) was proportional to the concentration of CAP over the range of 0.2~80.0 ng•mL-1 after incubation for 6 min at 25 ℃. The detection limit was 0.11 ng•mL-1. The immunosensor was employed to determine CAP in milk samples and the recovery rates exhibited a range of 88%~104%. The results were consistent to the tradition HPLC method. The proposed amperometric immunosensor was sensitive, quick, magnetic field controllable, low sample consumable and disposable, which was suitable for determining the trace chloramphenicol in food.
Herring sperm DNA (hsDNA) was used to modify 10 nm nanogold to obtain a resonance scattering (RS) spectral probe (AuhsDNA) for Hg2+. In the medium of pH 7.0 Tris-HCl-0.017 mol/L NaCl, Hg2+ interacted with AuhsDNA to form stable Hg2+-hsDNA complex and larger nanogold clusters, which could be removed by membrane filtration. The excess AuhsDNA in the filtration solution exhibited catalytic effect on the Fehling reagent-glucose reaction to form Cu2O particles that exhibit the strongest RS peak at 580 nm. With addition of Hg2+, the excess AuhsDNA in the filtration solution decreased accordingly, and the RS intensity at 580 nm decreased. The decreased RS intensity (ΔI580 nm) was linear to Hg2+concentration in the range of 1~833 nmol/L, with regression equation of ΔI580 nm=+0.9, coefficient of 0.9990 and detection limit of 0.3 nmol/L. The proposed method was applied to detect Hg2+ in water samples with satisfactory results.
An environmentally friendly energetic coordination compound [Zn(DAT)6](ClO4)2 (DAT=1,5-diaminotetrazole) has been synthesized by using DAT as ligand, characterized by elemental analysis and FT-IR spectroscopy. The single crystal structure of the title compound was determined by applying X-ray single crystal diffraction, which shows that the crystal belongs to trigonal crystal system with space group , and its crystal parameters: a=b=1.18398(9) nm, c=0.65700(10) nm, γ=120°, V=0.79760(15) nm3, and Z=1. There are one Zn2+, six DAT molecules and two in the minimum asymmetric unit of the title compound. The central zinc(II) cation is coordinated by six N atoms from six DAT molecules to form a six-coordinated and distorted octahedral structure. Thermal decomposition mechanism of [Zn(DAT)6]- (ClO4)2 was predicted based on DSC, TG-DTG and FT-IR analysis results. Also the kinetic parameters of the first exothermic process and sensitivities of the title compound have been studied. The result shows that the title compound has good friction sensitivity.
At first, relevant discussions on pyrolysis reaction rules of hydrocarbon fuels, including the sensitivity analysis of the specific reaction rule and the relative importance between these reaction rules, were presented. According to the 1-D representation rule of a chemical and the limited number of pyrolysis reaction rules, a program ReaxGen was developed for automatic generation of the detailed mechanisms for large hydrocarbons. Then, relevant thermochemical and kinetic databases were constructed. In addition, how to construct a detailed pyrolysis modeling of hydrocarbon fuels was discussed. Finally, the detailed pyrolysis kinetic model of n-heptane was constructed. The newly constructed mechanisms were modeled to obtain the product distribution and the conversion of the initial reactants, as well as the heat sink. The comparative discussions of the modeling results with those in literature have been made.