铽-环丙沙星体系的荧光特性及环丙沙星的测定

近中性条件下,铽（Ⅲ）能与环丙沙星（ｃｉｐｒｏｆｌｏｘａｃｉｎ）反应形成１：２的络合物。利用这一反应,建立了简单、快速、灵敏的测定环丙沙星的荧光方法,并且详细讨论了测定的各种条件。测定的最佳条件为：λｅｘ／λｅｍ＝３２５．０／５４５／０ｎｍ,Ｔｂ＾３＋（３．０＊１０－３ｍｏｌ／Ｌ）２．０ｍＬ,ｐＨ＝６．０的ＮａＡｃ－ＨＡｃ缓冲溶液２．０ｍＬ。线性范围１３－１０００μｇ／Ｌ,回归方程为Ｆ＝５．４２＋０．２２０７μｇ／Ｌ）（ｒ＝０．９９８）;检出限为１０μｇ／Ｌ。此方法用于血清及环丙沙星片剂的测定,结果令人满意。     

Separation and determination of two sesquiterpene lactones in Radix inulae and Liuwei Anxian San by microemulsion electrokinetic chromatography

A novel microemulsion electrokinetic chromatography (MEEKC) method for separating and determining two sesquoterpene lactones, alantolactone (AL) and isoalantolactone (IAL), in Radix inulae and Liuwei Anxian San has been developed. The effects of several important factors such as internal organic phases, concentration of microemulsion, concentration of acetonitrile, injection time and running voltage were systematically investigated to determine the optimum conditions. The optimum microemulsion system was composed of n-hexane (0.32% w/w), SDS (1.24% w/w), 1-butanol (2.64% w/w), acetonitrile (10% w/w) and 10 mm sodium tetraborate buffer (85.80% w/w, pH 9.2). The applied voltage was 20 kV. The analytes were detected at 214 nm. Regression equations revealed linear relationships (correlation coefficients 0.9950 for AL and 0.9946 for IAL) between the peak area of each analyte and the concentration. The limits of detection (defined as a signal-to-noise ratio of about 3) were approximately 0.45 microg/mL for AL and 0.56 microg/mL for IAL. The levels of the analytes were successfully determined with recoveries ranging from 98.2 to 104.3%. Furthermore, a simple and effective extraction method, with methanol in an ultrasonic water bath for 60 min, was used for sample preparing. Also, MEEKC was compared with micellar electrokinetic chromatography (MEKC) and shown better separation results.     

On-line capillary electrophoresis enrichment by combining chitosan trapping with surfactant assisted sample stacking for the ultratrace determination of organic acids in Plateau alfalfa roots

In this paper, four organic acids constituents of Plateau alfalfa roots have been identified and detected by a novel capillary electrophoresis (CE) strategy which combined chitosan (CS) trapping and cetyltrimethyl ammonium bromide (CTAB) assisted sample stacking. Under the optimized condition, organic acids, i.e., aconitic acid, gallic acid, citric acid and l-malic acid were concentrated and separated within 3 min. Validation parameters of this method (such as detection limits, linearity and precision) were also investigated and the limit of detection (LOD) was 2.41-53.9 ng mL⁻¹. Linearity was obtained over the magnitude range of 5-4000 ng mL⁻¹ approximately for different organic acids and 3 × 10²-1.5 × 10⁴ folds enrichment was achieved. The method has been applied to the determination of organic acids in roots of normal grown Plateau alfalfa and stressing affected Plateau alfalfa. Satisfactory results and recoveries were obtained in the analysis without costly and complicated sample pretreatment.     

Efficient Preparation of Large‐Sized Rings of Single‐Stranded DNA through One‐Pot Ligation of Multiple Fragments

Circular single‐stranded DNA (c‐ssDNA) has significant applications in DNA detection, the development of nucleic acid medicine, and DNA nanotechnology because it shows highly unique features in mobility, dynamics, and topology. However, in most cases, the efficiency of c‐ssDNA preparation is very low because polymeric byproducts are easily formed due to intermolecular reaction. Herein, we report a one‐pot ligation method to efficiently prepare large c‐ssDNA. By ligating several short fragments of linear single‐stranded DNA (l‐ssDNA) in one‐pot by using T4 DNA ligase, longer l‐ssDNAs intermediates are formed and then rapidly consumed by the cyclization. Since the intramolecular cyclization reaction is much faster than intermolecular polymerization, the formation of polymeric products is suppressed and the dominance of intramolecular cyclization is promoted. With this simple approach, large‐sized single‐stranded c‐ssDNAs (e.g., 200‐nt) were successfully synthesized in high selectivity and yield.     

二维材料范德华间隙的利用

Since their discovery, two-dimensional (2D) materials have attracted significant research attention owing to their excellent and controllable physical and chemical properties. These materials have emerged rapidly as important material system owing to their unique properties such as electricity, optics, quantum properties, and catalytic properties. 2D materials are mostly bonded by strong ionic or covalent bonds within the layers, and the layers are stacked together by van der Waals forces, thereby making it possible to peel off 2D materials with few or single layers. The weak interaction between the layers of 2D materials also enables the use of van der Waals gaps for regulating the electronic structure of the system and further optimizing the material properties. The introduction of guest atoms can significantly change the interlayer spacing of the original material and coupling strength between the layers. Also, interaction between the guest and host atom also has the potential to change the electronic structure of the original material, thereby affecting the material properties. For example, the electron structure of a host can be modified by interlayer guest atoms, and characteristics such as carrier concentration, optical transmittance, conductivity, and band gap can be tuned. Organic cations intercalated between the layers of 2D materials can produce stable superlattices, which have great potential for developing new electronic and optoelectronic devices. This method enables the modulation of the electrical, magnetic, and optical properties of the original materials, thereby establishing a family of 2D materials with widely adjustable electrical and optical properties. It is also possible to introduce some new properties to the 2D materials, such as magnetic properties and catalytic properties, by the intercalation of guest atoms. Interlayer storage, represented by lithium-ion batteries, is also an important application of 2D van der Waals gap utilization in energy storage, which has also attracted significant research attention. Herein, we review the studies conducted in recent years from the following aspects: (1) changing the layer spacing to change the interlayer coupling; (2) introducing the interaction between guest and host atoms to change the physico-chemical properties of raw materials; (3) introducing the guest substances to obtain new properties; and (4) interlayer energy storage. We systematically describe various interlayer optimization methods of 2D van der Waals gaps and their effects on the physical and chemical properties of synthetic materials, and suggest the direction of further development and utilization of 2D van der Waals gaps.     

钠离子电池新型Cu基隧道型氧化物正极材料研究

成本较为低廉的钠离子电池成为储能领域的新秀,备受关注.以Na₂CO₃,CuO,Fe₂O₃,MnO₂和TiO₂为原料,通过简单的固相反应法合成了一系列新型Cu基隧道结构化合物.通过X射线衍射（XRD）、扫描电子显微镜（SEM）和电化学性能测试对所得样品的结构、形貌以及电化学性能进行了表征.XRD结果表明材料结构与Na_0.44MnO₂一样为隧道结构,空间群为pbam.室温下的电化学性能测试表明Mn替代的样品在1.5~4.1 V的范围内表现出了90 mAh/g的比容量,循环稳定,倍率性能较好,1C容量保持率仍为74%.XPS结果验证了Cu在充放电过程中参与了变价.原位XRD结果表明Na_0.66Cu_0.17Mn_0.33Ti_0.5O₂电极材料在1.5~4.1 V的范围内可以保持稳定的隧道型结构.本工作首次报道了Cu在隧道型结构材料中的变价行为,为进一步设计隧道结构的材料以及钠离子电池正极材料提供新思路.     

Hydrogen absorption property and magnetism of SmFeAl and its hydrides

Magnetic properties of SmFeAl and its hydrides synthesized at 298–673 K under 40 bar hydrogen pressure were investigated by a superconducting quantum interference device (SQUID) from 4.2 to 300 K. SmFeAl and its hydrides have a mictomagnetic transition during the field-cooled process. In both SmFeAl and its hydrides, a shifted magnetic hysteresis cycle towards positive magnetization was observed. But when SmFeAlH_x decomposes completely into SmH_x and Fe–Al alloy, this special transition disappears.     

The study of the target emissivity and detection using a superconducting detector in the submillimeter wave region

This paper researches mainly the radiation characteristics of the target and detecting techniques by superconducting detector in the submillimeter wave(SMMW) region. The calculation of transition wavelength(TW) between Planck and Rayleigh-Jeans is given out. The experiment of detecting different targets is finished by use of superconducting detector possessing high performances. Through the experiments in paper we can select and determine the wave bands of SMMW detecting and imaging system. The many novel theoretical analyses and experimental results are expressed in Figs and tables of the paper. Finally, a part of calculating results and experimental datum detected by a superconducting detector in SMMW regions are given in this paper.     

Effect of annealing time on the structural and ferromagnetic properties of the GaMnN thin films

GaMnN thin films were deposited on a sapphire (0001) substrate by using laser assisted molecular beam epitaxy. Subsequently, the samples were annealed in the ammonia ambience at 1000 °C for different time lengths. The crystalline quality was improved gradually, and the room temperature ferromagnetism of our samples becomes stronger with the increase of the annealing time within 25 min. The X-ray photoelectron spectra analysis confirmed that the Mn³⁺ concentration in the GaMnN films increased after annealing. The stronger ferromagnetism was observed in the sample with the higher Mn³⁺ concentration. However, too long annealing time, such as 35 min, will lead to the degradation of the crystalline quality and the decrease of Mn³⁺ concentration, which results in the weakened ferromagnetism. The optimal annealing time is 25 min at 1000 °C in our experiments. Finally, the origin of the room temperature ferromagnetism in our samples was discussed preliminarily.