氢化物发生原子荧光光谱法测定铅基合金中砷

建立了以HG-AFS测定铅基合金样品中砷的简单方法,研究了共存元素可能引起的干扰并成功地加以解决,优化了氢化物发生条件及仪器的工作参数。KBH4最优浓度为1.0%(m/V),样品溶液和载流中HCl的最优浓度分别为10%(V/V)和5%(V/V)。实验表明,当硫脲存在时,Cu不干扰As的测定;Sb、Sn和Bi引起的干扰可以通过0.5%(m/V)KMnO4溶液在线吸收相应的氢化物加以消除。通过测定铅基合金标准样品以检验方法的准确性,由标准加入法得到的结果与标准值吻合。本方法的检出限为0.17μg/L,对40μg/LAs标准溶液连续测定11次的相对标准偏差为1.45%。     

离子交换色谱法检测离子液体中阴离子

建立了用阴离子交换分离柱、化学抑制模式、电导检测测定系列离子液体中BF-4阴离子及其他杂阴离子(F-、Cl-、Br-)含量的方法,并用于在线监控离子液体合成工艺中阴离子杂质含量.确定淋洗液组成为1.6 mmol/L Na2CO3+3.9 mmol/L NaHCO3,流速为0.6 mL/min.本方法对所测阴离子检出限分别为50 μg/L(F-、Br-)和80 μg/L(BF-4);线性范围在3个数量级以上;r＞0.999;回收率在98%～102%之间.方法用于对离子液体小试工艺样品分析及过程监控时,结果满意,样品的RSD小于2.6%(n＝6).     

Cyclodextrin Solubilization of the Antibacterial Agents Triclosan and Triclocarban: Effect of Ionization and Polymers

The natural β-cyclodextrin (βCD) and its complexes have limited solubility in aqueous solutions. This low aqueous solubility, as well as low aqueous solubility of the guest molecule (i.e. triclosan or triclocarban (TCC)), can result in low complexation efficiency (CE). The purpose of this study was to enhance the apparent intrinsic solubility (S ₀) of the guest molecule and its βCD complexes through ionization and addition of auxiliary compounds such as polymers, amino acids and metal ions. Both triclosan (pK _a 7.9) and TCC (pK _a 12.7) are weak acids. Addition of ethanol to the complexation medium enhanced S ₀ of both triclosan and TCC but at the same time ethanol lowered the stability constant (K _c ) of their βCD complexes resulting in overall lowering of CE. Addition of small amount of water-soluble polymers enhanced the βCD solubilization of both guests, and addition lysine enhanced the solubilization of TCC. Ionization of triclosan resulted in significant enhancement of CE and enhanced triclosan release from tablets containing triclosan/βCD complex. The effect of ionization was not as pronounced in the case of TCC.This revised version was published online in July 2005 with a corrected issue number.     

A modified internal lock-mass method for calibration of the product ions derived from sustained off-resonance irradiation collision-induced dissociation using a Fourier transform mass spectrometer

A modified internal lock-mass calibration method is introduced for improving the mass measurement accuracy of the product ion spectra derived from sustained off-resonance irradiation collision-induced dissociation (SORI-CID) Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. This method involves an initial external calibration of the Fourier transform mass spectrometer to obtain the initial A- and B-terms for the equation (f(i) = A/(m/z)(i) + B). The A-term is adjusted by using an empirical relationship between the up-shift of the A-term and the pulse-gas duration, whereas the B-term is adjusted by using the mass of the unfragmented precursor ion from the SORI-CID mass spectrum of the unknown sample as internal lock-mass. These adjusted A- and B-terms are then used to provide exact mass SORI-CID calibration for the unknown sample. The modified internal lock-mass method achieved average mass measurement accuracy of approximately 3 ppm which is significantly better than that of the conventional internal lock-mass calibration ( approximately 9 ppm) and is approaching that of the internal calibration ( approximately 2 ppm) and requires no addition of internal calibrant or instrumental modifications.     

Novel hydrogen-bonded three-dimensional network complexes containing cobalt-pyridine-2,6-dicarboxylic acid

The novel complex, Co(H₂O)₅[Co(2,6-pydc)₂] (1) has been prepared in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses and i.r. spectra. X-ray structural analysis revealed that three novel compounds each possess both – stacking and hydrogen-bonding interaction three-dimensional (3-D) networks.     

熔融碳酸盐燃料电池阳极材料表面改性

选择铌作为合金化元素，通过氟化物熔盐电化学表面合金化的方法对熔融碳酸盐燃料电池阳极材料镍进行表面改性，改性后的阳极材料的耐蚀性能与电催化性能均得到明显的改善。     

Linear alkyl benzene sulphonate (LAS) degradation by immobilized Pseudomonas aeruginosa under low intensity ultrasound

We studied the LAS degradation of immobilized Pseudomonas aeruginosa with low-intensity ultrasonic and the influence of original LAS concentration, pH, rotary velocity and different conditions of low-intensity ultrasonic irradiation on the degradation of LAS. In our experiment, the degradation rate of LAS was the main index. We found that low-intensity ultrasonic irradiation could improve the metabolism of microorganism cells and promote the LAS biodegradation of immobilized cells. In the experiment, 50 mg/l LAS were used to simulate wastewater, and low-intensity ultrasonic was considered. We found the influence was obvious, and the optimal degradation rate was acquired when the conditions of ultrasonic were frequency 24 kHz, power 8 W, stimulation time 5 s, intermissive time 30 s, and total time 10 min. The LAS degradation rate of immobilized cells with ultrasonic were respectively 40% and 9.5% higher than that of the suspending cells and immobilized cells without irradiation.     

On the vanishing dissipation limit for the incompressible MHD equations on bounded domains

In this paper,we investigate the solvability,regularity and the vanishing dissipation limit of solutions to the three-dimensional viscous magnetohydrodynamic(MHD)equations in bounded domains.On the boundary,the velocity field fulfills a Navier-slip condition,while the magnetic field satisfies the insulating condition.It is shown that the initial boundary value problem has a global weak solution for a general smooth domain.More importantly,for a flat domain,we establish the uniform local well-posedness of the strong solution with higher-order uniform regularity and the asymptotic convergence with a rate to the solution of the ideal MHD equation as the dissipations tend to zero.