High-precision frequency attenuation analysis and its application

Based on seismic attenuation theory in a fluid-filled porous medium, we improve conventional methods of low-frequency shadow analysis （LFSA） and energy absorption analysis （EAA） and propose a high-precision frequency attenuation analysis technology. First, we introduce the method of three-parameter wavelet transform and the time-frequency focused criterion and develop a high-precision time-frequency analysis method based on an adaptive three-parameter wavelet transform, which has high time-frequency resolution with benefit to LFSA and can obtain a single-peaked spectrum with narrow side-lobes with benefit to EAA. Second, we correctly compute absorption coefficient by curve fitting based on the nonlinear Nelder-Mead algorithm and effectively improve EAA precision. Practical application results show that the proposed frequency attenuation analysis technology integrated with LFSA and EAA can effectively predict favorable zones of carbonate oolitic reservoir. Furthermore, reservoir prediction results based on LFSA correspond with EAA. The new technology can effectively improve reservoir prediction reliability and reduce exploration risk.

Local Structure Analysis of Lead Zinc Niobate-Barium Titanate Ceramic by X-Ray Absorption Spectroscopy and Density Functional Calculation

The local structure of an alternative Pb（Zn1/3Nb2/3）O3-based perovskite ceramic is investigated. The 0.07BaTiO33-0.93Pb（Zn1/3Nb2/3）O3 ceramic is synthesized using a combination of Zn3Nb2O8 B-site precursor and BaTiO33 perovskite phase stabilizer. Then, x-ray absorption spectroscopy and density functional theory are employed to calculate the local structure configuration and formation energy of the prepared samples. Ba2＋ is found to replace Pb2＋ in AA-site with Zn2＋ occupying BB-site in Pb（Zn1/3Nb2/3）O3, while in the neighboring structure, Ti4＋4＋ replaces Nb5＋5＋ in BB-site with Pb2＋2＋ occupying AA-site. With the substitution of BaTiO33 in Pb（Zn1/3Nb2/3）O3, the bond length between Zn2＋ and Pb2＋ is longer than that of the typical perovskite phase of Pb（Zn1/3Nb2/3）O3. This indicates the key role of BaTiO33 in decreasing the steric hindrance of Pb2＋ lone pair, and the mutual interactions between Pb2＋ lone pair and Zn2＋ and the formation energy is seen to decrease. This finding of the formation energy and local structure configuration relationship can further extend a fundamental understanding of the role of BaTiO33 in stabilizing the perovskite phase in PbZn13Nb23O3-based materials, which in turn will lead to an improved preparation technique for desired electrical properties.

Anti-ultraviolet aging tests of asphalts adapting to environment in Tibetan Plateau of China

Ultraviolet （UV） aging is one of the main factors which cause premature damage of asphalt pavements in the Tibetan Plateau, China. According to the measured levels of UV radiation, aging tests of styrene-butadiene rubber （SBR） asphalts with different contents of three anti-UV-aging agents including nano-TiO2, CeO2 and carbon black are performed. Common indices, which include retained penetration after thin film oven tests （TFOT） and softening point, and strategic highway research program （SHRP） indices of aged asphalts are evaluated. Infrared absorption spectral analysis is performed on asphalt specimens with 0. 8% carbon black which have been aged for different aging times （500, 1000 and 1 500 h）. By grey incidence analysis, the optimal contents of anti-UV-aging agents are determined. The results show that TiO2 and CeO2 are not only good UV absorbing or shielding agents, but also strong oxidants. Carbon black is a good anti-UV-aging agent, and its optimal content is about 0. 8% of asphalt weight. UV aging of asphalt mainly occurs in the early stages of aging. The longer the aging time, the more severe the aging of asphalt.

Oxidation state specific analysis of arsenic species in tissues of wild-type and arsenic(+3 oxidation state)methyltransferase-knockout mice

Arsenic methyltransferase（As3mt） catalyzes the conversion of inorganic arsenic（i As） to its methylated metabolites, including toxic methylarsonite（MAs~Ⅲ） and dimethylarsinite（DMAs~Ⅲ）. Knockout（KO） of As3 mt was shown to reduce the capacity to methylate i As in mice. However, no data are available on the oxidation states of As species in tissues of these mice. Here, we compare the oxidation states of As species in tissues of male C57BL/6 As3mt-KO and wild-type（WT） mice exposed to arsenite（iA s~Ⅲ） in drinking water. WT mice were exposed to50 mg/L As and As3mt-KO mice that cannot tolerate 50 mg/L As were exposed to 0, 15, 20, 25 or30 mg/L As. iA s~Ⅲaccounted for 53% to 74% of total As in liver, pancreas, adipose, lung, heart, and kidney of As3mt-KO mice; tri- and pentavalent methylated arsenicals did not exceed 10% of total As. Tissues of WT mice retained iA s and methylated arsenicals： iA s~Ⅲ, MAs~Ⅲand DMAs~Ⅲ represented 55%‐68% of the total As in the liver, pancreas, and brain. High levels of methylated species, particularly MAs~Ⅲ, were found in the intestine of WT, but not As3mt-KO mice,suggesting that intestinal bacteria are not a major source of methylated As. Blood of WT mice contained significantly higher levels of As than blood of As3mt-KO mice. This study is the first to determine oxidation states of As species in tissues of As3mt-KO mice. Results will help to design studies using WT and As3mt-KO mice to examine the role of iA s methylation in adverse effects of iA s exposure.

Kinetics of fluorescence properties of Eu^(3+) ion in strontium-aluminiumbismuth-borate glasses

Eu3＋ doped strontium-aluminium-bismuth-borate glasses with the chemical composition（50–x）B2O3＋20Bi2O3＋7Al F3＋ 8Sr O＋15Sr F2＋x Eu2O3（where x=0.1 mol.%, 0.5 mol.%, 1.0 mol.% and 1.5 mol.%） were prepared by the conventional melt quenching technique.Structural properties of the prepared glasses were analysed through X-ray diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS） and Raman spectral techniques.Thermal stability of glass was analysed by differential thermal analysis（DTA） curve.Photoluminescence characteristics were studied using excitation, emission spectra and decay curves of Eu3＋ doped strontium-aluminium-bismuth-borate glasses.The Judd-Ofelt（J-O） intensity parameters, Ωλ（λ=2, 4 and 6） were obtained using emission spectra and was used to identify the nature of Eu3＋ ions with their surrounding ligands.Using J-O parameters the transition probabilities（A）, stimulated emission cross-sections σE p, branching ratios（βR） and radiative lifetimes（τmeas and τcal） were evaluated for the 5D0→7F J（J=0, 1, 2, 3 and 4） transition of Eu3＋ ions in the present glasses.The decay profiles were found to be non exponential for all the concentrations and the measured lifetimes（τmeas） were obtained from the decay profiles.The higher values of A, σE p, βR and quantum efficiency（η） for 5D0→7F2 emission transition at 617 nm confirmed the present glass was as active medium for red laser emission applications.

Synthesis,structural study,thermal,optical properties and characterization of the new compound[C6H7N2O2]3TeCl5·2Cl

The new organic-inorganic compound, [C_6H_7N_2O_2]_3TeCl_5·2Cl was synthesized and its structure was determined at room temperature in the triclinic system （P^-1） with the following parameters： a = 10.5330（11） ？, b = 10.6663（11） ？, c = 15.9751（16）？, α = 82.090（2）°, β = 71.193（2）°, γ = 68.284（2）°and Z = 2. The final cycle of refinement led to R = 0.057 and Rw = 0.149. The crystal structure was stabilized by an extensive network of N--H···Cl and non-classical C--H···Cl hydrogen bonds between the cation and the anionic group. Several thermal analysis techniques such as thermogravimetric analysis, differential scanning calorimetric analysis and evolved gas analysis were used. We used isoconversional kinetics methods to determine the kinetics parameters. We observe that the decomposition of [C_6H_7N_2O_2]_3TeCl_5·2Cl entails the formation hydrochloric acid of nitroaniline as volatiles. The infrared spectra were recorded in the4000–400 cm^（-1）frequency region. The Raman spectra were recorded in the external region of the anionic sublattice vibration 50–1500 cm^（-1）. The optical band gap was calculated from the UV-Vis absorbance spectra using classical Tauc relation which was found to be 3.12 and 3.67 eV.