Soft magnetization of a semi-hard/soft magnetic bilayer produced by oblique-incidence evaporation

The possibility of achieving soft magnetization in semi-hard magnetic films such as Fe, Fe_93.5Si_6.5, Fe₅₀Co₅₀ and Fe₇₀Co₃₀ is investigated by depositing films on an Fe₂₀Ni₈₀ underlayer by oblique-incidence evaporation. The magnetic anisotropy of the underlayer is strengthened to a depth of several lattice parameters by vapor deposition of the film at an oblique angle to the substrate surface. This method also allows magnetic anisotropy to be induced in strongly isotropic semi-hard magnetic overlayers to a thickness of a few thousands Angstroms. The coercive force of bilayer films measured along the hard-axis is reduced remarkably by this process, and the strength of the anisotropy field is demonstrated to be readily controllable. When magnetic anisotropy exists in both magnetic layers, a significant change is observed in the magnetization processes of the semi-hard magnetic layer and the coercive forces in the hard magnetization direction is dramatically reduced. Soft magnetization of the semi-hard magnetic layer cannot be achieved when magnetic anisotropy exists in only one of the magnetic layers.     

Observing the Stimulated Raman Gain Spectra of Solutions Using an Infrared Pump Pulse with Narrow Linewidth and a Low-Noise CW Probe Laser

Stimulated Raman gain (SRG) spectroscopy using infrared pump pulses with narrow linewidth and a low-noise cw probe infrared laser was proposed. High-resolution Raman spectra of solutions were obtained. The SRG spectra of crystal GaP, benzene, and toluene were measured to confirm the spectral resolution and sensitivity over the terahertz (THz) region. We discuss the polarization dependence of the spectral measurement of carbon tetrachloride. Our system can detect organic molecules in aqueous solutions.     

A numerical study on the formation of diffusion flame islands in a turbulent hydrogen jet lifted flame

This paper presents a numerical study on the formation of diffusion flame islands in a hydrogen jet lifted flame. A real size hydrogen jet lifted flame is numerically simulated by the DNS approach over a period of about 0.5 ms. The diameter of hydrogen injector is 2 mm, and the injection velocity is 680 m/s. The lifted flame is composed of a stable leading edge flame, a vigorously turbulent inner rich premixed flame, and a number of outer diffusion flame islands. The relatively long-term observation makes it possible to understand in detail the time-dependent flame behavior in rather large time scales, which are as large as the time scale of the leading edge flame unsteadiness. From the observation, the following three findings are obtained concerning the formation of diffusion flame islands. (1) A thin oxygen diffusion layer is developed along the outer boundary of the lifted flame, where the diffusion flame islands burn in a rather flat shape. (2) When a diffusion flame island comes into contact with the fluctuating inner rich premixed flame, combustion is intensified due to an increase in the hydrogen supply by molecular diffusion. This process also works for the production of the diffusion flame islands in the oxygen diffusion layer. (3) When a large unburned gas volume penetrates into the leading edge flame, the structure of the leading edge flame changes. In this transformation process, a diffusion flame island comes near the leading edge flame. The local deficiency of oxygen plays an important role in this production process.     

Determination of indium by graphite furnace atomic absorption spectrometry after coprecipitation with chitosan.

A sensitive and simple method for the determination of trace amounts of indium in water samples by graphite furnace atomic absorption spectrometry (GFAAS) after coprecipitation with chitosan was investigated. Indium was quantitatively preconcentrated from water samples by coprecipitation with chitosan at pH 7.0-9.0. The coprecipitant was easily dissolved with acetic acid, and indium in the resulting solution was determined by GFAAS. The addition of lanthanum as a chemical modifier was more effective for the atomic absorbance of indium. The detection limit (S/N > or = 3) for indium was 0.04 microg dm(-3), and the relative standard deviations (n = 5) were 3.5-4.5% at 1.0 microg/100 cm3. The results obtained in this study indicate that the proposed method can be successfully applied to the determination of trace indium in water samples.     

Dynamics of Photoelectrons and Structural Changes of Tungsten Trioxide Observed by Femtosecond Transient XAFS

The dynamics of the local electronic and geometric structures of WO₃ following photoexcitation were studied by femtosecond time‐resolved X‐ray absorption fine structure (XAFS) spectroscopy using an X‐ray free electron laser (XFEL). We found that the electronic state was the first to change followed by the local structure, which was affected within 200 ps of photoexcitation.     

A Ruthenium(III)–Oxyl Complex Bearing Strong Radical Character

Proton‐coupled electron‐transfer oxidation of a Ru^II?OH₂ complex, having an N‐heterocyclic carbene ligand, gives a Ru^III?O^. species, which has an electronically equivalent structure of the Ru^IV=O species, in an acidic aqueous solution. The Ru^III?O^. complex was characterized by spectroscopic methods and DFT calculations. The oxidation state of the Ru center was shown to be close to +3; the Ru?O bond showed a lower‐energy Raman scattering at 732 cm^?1 and the Ru?O bond length was estimated to be 1.77(1) Å. The Ru^III?O^. complex exhibits high reactivity in substrate oxidation under catalytic conditions; particularly, benzaldehyde and the derivatives are oxidized to the corresponding benzoic acid through C?H abstraction from the formyl group by the Ru^III?O^. complex bearing a strong radical character as the active species.     

添加碳元素合成化学计量比LiNiO2

本文采用添加碳元素、葡萄糖及使用多种试剂为原料的合成方法,合成了具有化学计量比的LiNiO2.分析了这些方法在合成反应中的作用,同时给出了合成LiNiO2的最佳反应条件.     

A Pretreatment Method for GC–MS Determination of Endocrine Disrupting Chemicals in Mollusk Tissues

Automatic soxhlet extraction followed by silica gel cartridge cleanup process was developed as a pretreatment method for GC–MS determination of seven endocrine disrupting chemicals in mollusk tissues. Operation parameters including extraction time, adsorption flow rate and elution flow rate were optimized as 140 min, 2 mL min^?1 and 2 mL min^?1, respectively. Thirty percent dichloromethane in n-hexane and 70% dichloromethane in n-hexane were used as elution solvents in turn. Recovery rates were 93.7, 91.7, 84.5, 83.3, 88.4, 81.2, and 79.7% for nonylphenols (NPs), bisphenol A (BPA), 17α-ethynylestradiol (EE2), estrone (E1), 17α-estradiol (17α-E2), 17β-estradiol (E2), and estriol (E3), respectively. Acceptable relative standard derivations ranged from 8.5 to 12.1%. Method detection limits ranged from 0.27 to 0.68 ng g^?1 dry weight (dw), and quantitative detection limits ranged from 0.62 to 1.26 ng g^?1 dw. The method was successfully applied to five mollusk species in Dapeng Bay of China to verify its practicability, and NPs, BPA, EE2, E1 and 17α-E2 were detected in the range from 1.6 to 131.5 ng g^?1 dw.     

Application of log D for the prediction of hydrophobicity in the advanced Marfey's method

In the advanced Marfey's method, the resolution between the diastereomers derivatized with 1-fluoro-2,4-dinitrophenyl-5-l-leucinamide (l-FDLA) and 1-fluoro-2,4-dinitrophenyl-5-d-leucinamide (d-FDLA) is reflected by the difference of hydrophobicity of the two functional groups at the asymmetric carbon. However, no effective method has been developed for the estimation of hydrophobicity so far. For this purpose, we introduced log D from the ACD Labs LogD and applied it to relatively simple primary amines, amino acids and secondary alcohols in the present study. It was found that the difference of the retention times (Δt_R) correlated with that of log D (Δlog D) for both diastereomers based on the obtained experimental results. Based on these results, the following procedure was proposed for the non-empirical determination of the absolute configuration of primary amines including amino acids and secondary alcohols: (1) estimate the hydrophobicity by the calculation of log D for the two substituent groups at the asymmetric carbon, (2) locate the trans-type arrangement of the two more hydrophobic substituents in the l-DLA derivative and judge the asymmetric carbon to be R or S in the trans-type that is eluted first, (3) derivatize the desired compound with l- or d-FDLA and analyze by LC/MS, and (4) compare the elution order with the prospective one and determine the absolute configuration at the asymmetric carbon. Furthermore, log D could also be used to predict the retention times of unavailable amino acids and small peptides, indicating that the combination of the advanced Marfey's method with log D would provide more reliable structural information on a mixture composed of amino acids and small peptides. The developed method is being applied to more complicated compounds.     

A simple, iron-catalyzed, pyridine-assisted hydrogen peroxide epoxidation system

A simple and inexpensive system comprised of H(2)O(2)-pyridine-FeCl(3)·6H(2)O for the catalysis of olefin epoxidation was established. Intriguingly, the reactivity of this system greatly depends on the amounts of pyridine. Various substrates, including aromatic and aliphatic olefins, were epoxidized by this simple system in moderate to excellent yields.