Synthesis,magnetic and electrical transport properties of magnetoresistance material Sr2FeMoO6 by microwave sintering

Magnetoresistance material Sr₂FeMoO₆ with double perovskite structure was synthesized by microwave sintering method using SrCO₃, Fe₂O₃ and MoO₃ as raw materials, with MnO₂ for microwave absorber. The phase structure, magnetic and electrical transport properties were investigated by X-ray powder diffraction (XRD) and vibrating-sample magnetometer. XRD analysis shows that the as-synthesized sample is Sr₂FeMoO₆ with tetragonal crystal structure and I4/mmm space group. The unit cell parameters are a=0.5587 nm, c=0.7894 nm, volume=0.2464 nm³. The calculated grain size of the sample is 31.62 nm, which is obtained by the Scherrer formula using the diffraction data. Magnetism testing results show that the sample Sr₂FeMoO₆ is ferromagnetic with the magnetic transition temperature of about 380 K. Under 1.0 T magnetic field, the saturation and spontaneous magnetization of Sr₂FeMoO₆ is 1.25 μ_B/f.u. and 1.00 μ_B/f.u. at room temperature. The magnetoresistance ratio of the sample is 28%. Electrical transport properties testing results indicate that the sample exhibits typical semiconductor behavior. The conductive mechanism of Sr₂FeMoO₆ is highly dependent on temperature: within the temperature range of 100–300 K, the mechanism is attributed to the small polaron variable-range hopping model; while it is ascribed to the adiabatic small polaron model within the temperature range of 80–100 K.     

大面积等离子体片密度分布分析

利用空心阴极放电产生了尺寸为60 cm× 60 cm× 2 cm的大面积等离子体面. 在实验室条件下对大面积等离子体片的密度分布进行了测量. 由于高压放电脉冲脉宽较短, 实验中改变了测量方法, 同时, 在中等磁场影响下, 为了得到真实的等离子体密度, 进行了必要的数值修正.在放电电流为1---6 A时, 测量了二维的电子密度分布. 另外, 测量并讨论了其他环境参数对等离子体密度的影响. 电子密度的分布情况对与微波波束切换相当重要. 由空心阴极增强型放电产生的大面积等离子体面具有反射X波段(8---12 GHz) 微波需要的足够稠密的电子密度和足够均匀的密度分布, 这是等离子体面在雷达系统中取代金属面板的有利条件.     

Facile synthesis and platinum complexes of 4',5,5'-trisubstituted-2,2':6',2'-terpyridines

The synthesis of trisubstituted 4',5,5' terpyridines is described. The strategy begins with synthesis of 2-acetyl-5-bromopyridine (3) from 2,5-dibromopyridine, substitution of the bromine in 3 using a variety of metal-catalyzed reactions and then formation of the terpyridine using the Krohnke reaction. The complexes have been prepared by reaction of [Pt(PhCN)(2)Cl(2)] with the appropriate silver salt followed by addition of the terpyridyl ligand. The crystal structure of two complexes have been determined via X-ray diffraction and the MLCT (metal-to-ligand charge-transfer) emissions determined by UV/Vis spectroscopy.     

Design and synthesis of affinity ligands and relation of their structure with adsorption of proteins

Affinity chromatography has played an increasingly important role both in the pharmaceutical industry and academic research. In the present study, we report our preliminary investigation on the relationship between the affinity ligand structure and its adsorption to multi-protein samples. The structure of the ligands, including the size of the ring (cyclic group) and the length of the chain (linear group), has a great impact on the adsorption of ligands to proteins. Meanwhile, the functional groups that the ligands carry are also closely related to the adsorption of ligands to proteins. This research provides good guidance for the design and synthesis of affinity materials in affinity chromatography. It is also useful to other protein-ligand interaction-related research.     

Simultaneous analysis of hydrochlorothiazide, triamterene and reserpine in rat plasma by high performance liquid chromatography and tandem solid-phase extraction

A tandem solid-phase extraction method (SPE) of connecting two different cartridges (C(18) and MCX) in series was developed as the extraction procedure in this article, which provided better extraction yields (>86%) for all analytes and more appropriate sample purification from endogenous interference materials compared with a single cartridge. Analyte separation was achieved on a C(18) reversed-phase column at the wavelength of 265 nm by high-performance liquid chromatography (HPLC). The method was validated in terms of extraction yield, precision and accuracy. These assays gave mean accuracy values higher than 89% with RSD values that were always less than 3.8%. The method has been successfully applied to plasma samples from rats after oral administration of target compounds.     

Simultaneous quantification of three iridoids in rat plasma after oral administration of Zhi-zi-chi decoction using LC-MS

A sensitive and efficient liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for the simultaneous determination of geniposide, 6α-hydroxygeniposide, and genipin gentiobioside in rat plasma. After the addition of internal standard (I.S.) salidroside and acidification (formic acid, 0.1%), plasma samples were carried out by protein precipitation with acetonitrile and separated on a Kromasil C(18) column (200 mm × 4.6 mm, 5 μm) within a runtime of 15.0 min. The linear ranges were 2-250 ng/mL for both 6α-hydroxygeniposide and genipin gentiobioside and 2-2000 ng/mL for geniposide, respectively. The lower limit of quantification (LLOQ) was 2 ng/mL for all the analytes. The validated method was successfully applied to the pharmacokinetics study of geniposide, 6α-hydroxygeniposide, and genipin gentiobioside in rats after oral administration of Zhi-zi-chi decoction.     

Effect of end groups on the raman spectra of lycopene and β-carotene under high pressure

The Raman spectra of all-trans-lycopene in n-hexane were measured under high pressure, and the results compared with those of β-carotene. The different pressure effects on Raman spectra are analyzed taking into account the different structures of lycopene and β-carotene molecules. It is concluded that: (a) the vibronic coupling between the S? and S? states of β-carotene is stronger than that of lycopene, (b) the diabatic frequency increment of the ν? mode is more susceptible to pressure than that of the ν? mode for lycopene, and (c) β-rings rotation can relieve the pressure effect on the C=C bond length in β-carotene. This work provides some insights for elucidating the structural and environmental effects on Raman spectra of carotenoids.     

Design and synthesis of novel mesostructured metal-organic frameworks templated by cationic surfactants via cooperative self-organization

A novel design strategy to synthesize highly ordered hexagonally mesostructured metal-organic framework materials was successfully explored, which means the realization of directly cooperative self-assembly of metal ions, bridging ligands and surfactants in an aqueous system.     

一种水飞蓟宾恶唑衍生物的合成及体外抗肿瘤活性研究

水飞蓟宾多作为保肝药使用,近年来因其在抗肿瘤方面显示的良好潜力而备受关注。为提高水飞蓟宾的抗肿瘤活性,以天然产物水飞蓟宾为先导化合物,合成一系列水飞蓟宾衍生物,其化学结构经1H NMR、13C NMR、MS确证。采用MTT法测试目标化合物对人乳腺癌细胞(MCF-7)和人胃癌细胞(SGC-7901)的体外抗肿瘤活性;并运用分子对接的方法分析目标化合物与HER2靶点的作用方式。结果表明,目标化合物对两种癌细胞的抑制率均优于水飞蓟宾,其中衍生物Ⅱ3和Ⅱ9与阳性对照药拉帕替尼和阿法替尼抑制作用相当,衍生物Ⅱ3和Ⅱ9能与HER2靶蛋白周围的氨基酸残基通过氢键紧密结合。本研究可为新型抗肿瘤药物的研发提供参考。