Adsorption properties and photocatalytic activity of TiO2/activated carbon fiber composite

Photocatalysts of titanium dioxide (TiO₂) and TiO₂/activated carbon fiber (TiO₂/ACF) composite were prepared by sol-gel method, followed by calcining the pure TiO₂ sols and the TiO₂/ACF sols at 500°C for 2 h in a N₂ atmosphere, respectively. These photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N₂ adsorption-desorption isotherms measurement. Batch experiments were conducted to study the adsorption property of TiO₂/ACF composite using methylene blue as adsorbate. The adsorption data obtained from different batch experiments were analyzed using pseudo-second-order kinetic model, the experimental data can be adequately described by the pseudo-second-order equation. The photodecomposition behavior of TiO₂/ACF was investigated in aqueous solution using methylene blue as target pollutant. It was found that methylene blue could be removed rapidly from water by TiO₂/ACF, the photocatalytic decomposition was obviously improved when the photocatalyst was used. Kinetics analysis revealed that the photocatalytic decomposition reaction can be described well by a first-order rate equation.     

Fusion of urban remote image based on multi-characteristics

A fusion approach is proposed to refine the resolution of urban multi-spectral images using the corre sponding high-resolution panchromatic (PAN) images. Firstly, the two images are decomposed by wavelet transformation, and five texture features are extracted from high-frequency detailed sub-images. Then a multi-characteristics fusion rule is used to merge wavelet coefficients from the two images according to the extracted features. Experimental results indicate that, comparing with the non-characteristic methods, the proposed method can efficiently preserve the spectral information while improving the spatial resolution of the urban remote sensing images.     

THE MAXIMUM NUMBER OF INTERSECTIONS BETWEEN TWO PLANE RECTANGULAR PATHS

We show that the maximum number of intersections between two plane rectangular paths with lengths m and n: 2 ≤ m ≤ n, is 4n 2, if m=4 and n≡1(mod 3); and it is mn 1 otherwise.     

Effects of carbonization and substrate temperature on the growth of 3C-SiC on Si(1 1 1) by SSMBE

The growth of 3C-SiC on Si(1 1 1) substrate was performed at different carbonization temperatures and substrate temperatures by solid-source molecular beam epitaxy (SSMBE). The properties of SiC film were analyzed with in situ reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The best carbonization temperature of 810 °C was found to be optimal for the surface carbonization. The quality of SiC film grown on Si at substrate temperature of 1000 °C is best. The worse crystalline quality for the sample grown at higher temperature was attributed to the large mismatch of thermal expansion coefficient between SiC and Si which caused more dislocation when sample was cooled down to room temperature from higher substrate temperature. Furthermore, the larger size of single pit and the total area of the pits make the quality of SiC films grown at higher temperature worse. More Si atoms for the sample grown at lower temperature were responsible for the degradation of crystalline quality for the sample grown at lower temperature.     

Multidimensional Gas Chromatography–Mass Spectrometry Method for Fingerprinting Polycyclic Aromatic Hydrocarbons and Their Alkyl-Homologs in Crude Oil

The composition of polycyclic aromatic hydrocarbons in crude oil is usually too complex to use standard capillary gas chromatography to separate all of the components. In this study, a multidimensional gas chromatography–mass spectrometry (GC-MS) technique was used to analyze polycyclic aromatic hydrocarbon fractions of crude oil collected from the Dongying oil field in the Bohai Sea. A DB-17MS column (30?m?×?0.25?mm?×?0.25?µm) was used as a prefractionating column and only selected heart-cuts were transferred to the second chromatographic dimension (HP-5MS, 15?m?×?0.25?mm?×?0.25?µm) by a pressure-adjusted continual flow-type switching device for quantification of the polycyclic aromatic hydrocarbons. The chromatographic elements and parameters, such as detector selection and column combinations, were optimized. Naphthalene, phenanthrene, fluorene, dibenzothiophene, chrysene, and their C₁–C₄ alkyl homologs were identified. The profile of the polycyclic aromatic hydrocarbons obtained using the multidimensional GC-MS method was compared with the results obtained by traditional one-dimensional GC-MS.     

Calorimetric studies on the electrorefining process of copper

Calorimetric measurements were carried out on the electrorefining of copper using different current densities with a Calvet type microcalorimeter at room temperature. The ratio (R) of the measured heat (Q _m orW _m) to the input electric energy (Q _in orW _in) and the excess heat (Q _ex orW _ex), i.e. the difference betweenQ _m (orW _m) andQ _in (orW _in) during the electrorefining process were discussed in terms of general thermodynamics. It was found thatR andQ _ex were related to the current density employed in the experiment and varied as a logarithmic function. The results obtained here indicate that the heat generation under different conditions, such as different currents or voltages, may be caused partially by the irreversibility of the process or by some unknown processes.Dedicated to Prof. Menachem Steinberg on the occasion of his 65th birthdayThe authors would like to acknowledge the extreme encouragements and help of Professor Shuyi Liu (University of Science and Technology of China) and Professors Fu Tan and Guoquan Liu (Institute of Chemistry, Academia Sinica).This study was supported by the National Nature Science Foundation of China.     

Excess molar enthalpies for binary mixtures of trimethyl phosphate with alkanols {CH3(CH2)nOH, n = 0–3} at 298.15 K

The excess molar enthalpies () for the binary mixtures of trimethyl phosphate (TMP) with alkanols {CH₃(CH₂)_nOH, n = 0–3} have been measured with an isothermal calorimeter at 298.15 K and atmospheric pressure. The values are positive for all the mixtures over the whole composition range. The values increase in the order methanol < ethanol < 1-propanol < 1-butanol. The experimental results have been correlated with the Redlich–Kister equation.     

关于测定二元系中挥发组分活度系数的GLPC方法的研究

GLPC法测定二元系中挥发组分有限浓度时的活度系数曾为Chueh和Ziegler、Conder和Purnell、Chch和Parcher等所探讨,但因后续工作太少,迄今未能成熟,将这一方法得到肯定,对于研究二元溶液的热力学是有意义的,经过反复比较,我们决定对Chueh和Ziegler的方法作进一步探讨。     

Fabrication of self-assembled ultrathin photochromic films containing mixed-addenda polyoxometalates H5[PMo10V2O40] and 1,10-decanediamine

A layered phosphovanadomolybdate/1,10-decanediamine (1,10-DAD) self-assembled ultrathin film was fabricated by means of alternating adsorption of mixed-addenda polyoxometalates (POMs) (phosphovanadomolybdate, H₅[PMo₁₀V₂O₄₀]) and 1,10-DAD, and its photochromic properties were investigated. It is found that the self-assembled multilayer (SAM) film shows high-photochromic response, excellent photochromic stability and reversibility. The photochromic behavior of the SAM is closely related to the reduction potentials of addenda atoms in mixed-addenda POMs. In the case of photo-reduced mixed-addenda POMs, the electron is localized on the more reducible atom, and the addenda atoms with higher reduction potentials show prior photochromism compared with those with lower reduction potentials. The coloration speed is improved after introduction of V into molybdenum POM. The well-ordered lamellar structure of the film was well maintained during the coloration.