Infrared spectra of the high-Tc TlBaCaCuO superconductors

The TlBaCaCuO superconductors with zero resistance at temperatures in the range of 100–123 K have been sintered by solid state reactions. Electron microscopy and X-ray diffraction studies reveal that they are multiphased, containing both Tl₂Ba₂CaCu₂O₈ and Tl₂Ba₂Ca₂Cu₃O₁₀ superconducting phases. Infrared spectra have been measured at room temperature for the multiphase samples. The spectra display structures at 590 cm^-1 (P₁) and 530 cm^-1 (P₂) which seem characteristic to Cu-O stretching modes. The difference ΔP between P₁ and P₁ has been found to be related to the superconducting transition temperature. Smaller ΔP corresponds to a higher T_c. The electron-like excitation of0.1 eV and the phonon-like structure at 850 cm^-1 are also found to be important for high T_c.     

4,7-(氯磺酸基苯基)-1,10-菲啰啉-2,9-二羧酸-铕标记甲胎蛋白抗体

在合成BCPDA基础上 ,对甲胎蛋白抗体与BCPDA连接及与铕离子螯合条件进行了研究。BCPDA与甲胎蛋白抗体反应后 ,分离纯化最佳淋洗液为pH 9.1的 0 .1mol/L碳酸盐缓冲溶液 ,BCPDA用量为甲胎蛋白抗体量 (mol)的 12 0～ 16 0倍 ;反应时间为 30min。讨论了Eu3 + BCPDA AFP抗体螯合物的荧光光谱 ,最佳温育时间为6 0min ,体系pH值为 7.8的Tris HCl溶液。当Eu3 + 浓度为 10 -6mol/L时 ,BCPDA的检出限为 4 .3× 10 -11mol/L。     

铕苯丙氨酸配合物与DNA相互作用的循环伏安法和紫外光谱法研究

运用循环伏安法和紫外光谱法研究了Ｅｕ（ｐｈｅ）３＾３＋与ＤＮＡ的相互作用。Ｅｕ（ｐｈｅ）３＾３＋与ＤＮＡ作用后，循环伏安曲线的峰电流密度减小，峰电位差稍有增中，扩散系数减小，紫外光谱的特征吸收峰呈明显的减色效应，这可能是Ｅｕ（ｐｈｅ）３＾３＋与ＤＮＡ因静电引力形成加合物以及Ｅｕ（ｐｈｅ）３＾３＋有很强的遮蔽负电荷 作用，促使碱基面与碱基面的进一步堆积所致。     

基于渐进核图割的SAR图像自动分割

合成孔径雷达(Synthetic Aperture Radar,SAR)图像是遥感目标检测与分割等研究的重要数据源。提出了一种渐进核图割分割方法,该方法通过迭代进行二类聚类分割,自动实现合成孔径雷达SAR图像中多目标的分割。实验结果表明,该方法能够有效地实现复杂场景SAR图像的多目标分割。     

The application of trigonal curve to the Mikhailov–Shabat–Sokolov flows

Resorting to the characteristic polynomial of Lax matrix for the Mikhailov–Shabat–Sokolov hierarchy associated with a \({3 \times 3}\) matrix spectral problem, we introduce a trigonal curve, from which we deduce the associated Baker–Akhiezer function, meromorphic functions and Dubrovin-type equations. The straightening out of the Mikhailov–Shabat–Sokolov flows is exactly given through the Abel map. On the basis of these results and the theory of trigonal curve, we obtain the explicit theta function representations of the Baker–Akhiezer function, the meromorphic functions, and in particular, that of solutions for the entire Mikhailov–Shabat–Sokolov hierarchy.     

Determination of astaxanthin in feeds using high performance liquid chromatography and an efficient extraction method

A high performance liquid chromatography method using an efficient extraction method was developed for the determination of astaxanthin in eight kinds of animal feed. The chromatographic separation was achieved using a C₁₈ reversed-phase column, using methanol and acetonitrile as the mobile phases with a flow rate of 1 mL/min. The feeds containing astaxanthin were first treated with maxatase, to cause enzymatic hydrolysis, and then extracted with dichloromethane. The optimized method produced recoveries of between 82.4% and 100% for all eight kinds of feed, and the coefficients of variation were lower than 4.28%. The limit of detection, defined as the concentration that gave a signal-to-noise ratio of 3, for astaxanthin was estimated to be 0.1 µg/g. The limit of quantification, defined as the lowest spiked concentration that gave an appropriate level of precision and accuracy, was 0.3 µg/g. Finally, the method developed was used to determine astaxanthin in real, commercially sourced, feed samples. The method met the requirements for the determination of astaxanthin in feed, providing satisfactory recoveries of 70–110%.     

Organic–inorganic hybrids based on polyoxometalates and copper coordination complexes

Two new hybrids based on Keggin polyoxometalates have been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, TG analysis, and single-crystal X-ray diffraction. The crystal structure analyses reveal that complex 1 has an infinite 1D chain structure, constructed from [Cu(2,2′-bpy)(4,4′-bpy)(H₂O)] fragments and [H₂PMo₁₁VO₄₀]^2? building blocks. Complex 2 has a 2D molecular ladder structure, with a basic structural unit composed of one bis(µ-OH) dicopper(II) [Cu₂(OH)₂(H₂O)₂(4,4′-bpy)₃] fragment, one [HPMo₁₂O₄₀], and four water molecules. The [Cu₂(OH)₂(H₂O)₂(4,4′-bpy)₃] units connect alternately to form edge rails. The [HPMo₁₂O₄₀] clusters act as rungs of the ladder, linking pairs of Cu atoms from the two adjacent edge rails. The electrochemical behavior of the complexes in modified carbon paste electrodes and their electrocatalytic reduction of nitrite were investigated.     

Effects of duty cycle on the preparation and property of PbO<Subscript>2</Subscript>-CeO<Subscript>2</Subscript> nanocomposite electrodes

PbO₂-CeO₂ nanocomposite electrodes were prepared by pulse electrodeposition in the lead nitrate solution containing CeO₂ nanoparticles with different duty cycles. The effects of duty cycle on the morphology and phase structure were investigated by scanning electronic microscopy (SEM) and X-ray diffraction (XRD), respectively. The SEM and XRD results show that the decrease of duty cycle can reduce the grain size of PbO₂-CeO₂ nanocomposite electrodes and make the electrodes more compact. The CeO₂ content in composite electrodes increases with the decrease of duty cycle. The steady-state polarization curves and accelerated life tests demonstrate that the oxygen evolution overpotential and service life of PbO₂-CeO₂ nanocomposite electrodes increase with the decrease of duty cycle. The service life of PbO₂-CeO₂ nanocomposite electrodes prepared with 25 % duty cycle reaches 218 h which is 1.8 times longer than that of PbO₂-CeO₂ nanocomposite electrodes prepared by direct electrodeposition. The bulk electrolysis shows that the degradation of malachite green (MG) on the PbO₂-CeO₂ nanocomposite electrodes is the pseudo-first-order reaction and the MG and chemical oxygen demand (COD) removal efficiency on PbO₂-CeO₂ nanocomposite electrodes increases with the decrease of duty cycle, which can be attributed to the higher oxygen evolution overpotentials, electrochemical active surface area, and CeO₂ content in the composite electrodes.     

Three polymorphs of an inclusion compound of 2,2′‐(disulfanediyl)dibenzoic acid and trimethylamine

Polymorphism is the ability of a solid material to exist in more than one form or crystal structure and this is of interest in the fields of crystal engineering and solid‐state chemistry. 2,2′‐(Disulfanediyl)dibenzoic acid (also called 2,2′‐dithiosalicylic acid, DTSA) is able to form different hydrogen bonds using its carboxyl groups. The central bridging S atoms allow the two terminal arene rings to rotate freely to generate various hydrogen‐bonded linking modes. DTSA can act as a potential host molecule with suitable guest molecules to develop new inclusion compounds. We report here the crystal structures of three new polymorphs of the inclusion compound of DTSA and trimethylamine, namely trimethylazanium 2‐[(2‐carboxyphenyl)disulfanyl]benzoate 2,2′‐(disulfanediyl)dibenzoic acid monosolvate, C₃H₁₀N⁺·C₁₄H₉O₄S₂⁻·C₁₄H₁₀O₄S₂, (1), tetrakis(trimethylazanium) bis{2‐[(2‐carboxyphenyl)disulfanyl]benzoate} 2,2′‐(disulfanediyl)dibenzoate 2,2′‐(disulfanediyl)dibenzoic acid monosolvate, 4C₃H₁₀N⁺·2C₁₄H₉O₄S₂⁻·C₁₄H₈O₄S₂²⁻·C₁₄H₁₀O₄S₂, (2), and trimethylazanium 2‐[(2‐carboxyphenyl)disulfanyl]benzoate, C₃H₁₀N⁺·C₁₄H₉O₄S₂⁻, (3). In the three polymorphs, DTSA utilizes its carboxyl groups to form conventional O—H…O hydrogen bonds to generate different host lattices. The central N atoms of the guest amine molecules accept H atoms from DTSA molecules to give the corresponding cations, which act as counter‐ions to produce the stable crystal structures via N—H…O hydrogen bonding between the host acid and the guest molecule. It is noticeable that although these three compounds are composed of the same components, the final crystal structures are totally different due to the various configurations of the host acid, the number of guest molecules and the inducer (i.e. ancillary experimental acid).     

Rapid extraction and determination of 25 bioactive constituents in Alpinia oxyphylla using microwave extraction with ultra high performance liquid chromatography with tandem mass spectrometry

A novel and rapid microwave extraction and ultra high performance liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of 25 bioactive constituents (including two new constituents) in Fructus Alpinia oxyphylla. The optimized conditions of the microwave extraction was a microwave power of 300 W, extraction temperature of 80°C, solvent‐to‐solid ratio of 30 mL/g and extraction time of 8 min. Separation was achieved on a Waters ACQUITY UPLC^® HSS C₁₈ column (2.1 mm× 50 mm, 1.8 μm) using gradient elution with a mobile phase consisting of acetonitrile and 1 mM ammonium acetate at a flow rate of 0.2 mL/min. This is the first report of the simultaneous determination of 25 bioactive constituents in Fructus Alpinia oxyphylla by ultra high performance liquid chromatography with tandem mass spectrometry. The method was validated with good linearity, acceptable precision and accuracy. The validated method was successfully applied to determine the contents of 25 bioactive constituents in Fructus Alpinia oxyphylla from different sources and the analysis results were classified by hierarchical cluster analysis, which indicated the effect of different cultivation regions on the contents of constituents. This study provides powerful and practical guidance in the quality control of Alpinia oxyphylla and lays the foundation for further research of Alpinia oxyphylla.