AA3型连续流动分析仪测定天然泉水中的亚硝酸盐氮

建立应用AA3连续流动分析仪测定天然泉水中亚硝酸盐氮的方法。在0-5.00mg·L^-1线性区间内该方法线性关系好,较高的精密度和准确度,检出限低。与GB／T8538-2008饮用天然矿泉水检验方法中亚硝酸盐氮分光光度法相比,该方法具有自动进样、分析速率快、试剂耗量低等优点,可应用于大批量天然泉水分析.     

The polynomial reconstruction problem: The first 50 years

The problem of reconstructing the characteristic polynomial of a graph of order at least 3 from the collection of characteristic polynomials of its vertex-deleted subgraphs was posed by Cvetkovi? in 1973 as a spectral counter part to the well-known Ulam's reconstruction conjecture. Over the last 50 years, this problem has received notable attention, many positive results have been obtained, but in the general case the problem is still unresolved. In particular, no counter example is found in literature. In this expository paper we survey classical and some more recent results concerning the polynomial reconstruction problem, discuss some related problems, variations and generalizations.     

2-F-环氧丁烷与几种生物小分子间的赝氢键结构

采用密度泛函B3LYP(Becke,three-parameter,Lee-Yang-PaH)/6-311++G**和HF(Hartree Fock)/6-311++G**方法,从理论上探讨了2-F-环氧丁烷分别与几种常见而重要的生物小分子咪唑(Iminazole)、噻唑(Thiazole)和恶唑(Oxazo1e)等分子间的弱相互作用,发现分子间同时存在N…H常规氢键和C-F…H-C赝氢键结构.弱相互作用能计算表明3个复合物的相对稳定性相当.计算结果表明,在C-F…H-C赝氢键结构中,与电子的直接供体F密切相关的共价键C-F键长增大,伸缩振动的频率红移,而作为电子受体的H-C基团,其C-H键伸缩振动光谱蓝移;另外,电子密度拓扑性质表明C-F…H-C赝氢键的共价性及离子性均与常规氢键相当.     

Microwave dielectric and magnetic properties of superparamagnetic 8-nm Fe3O4 nanoparticles

The superparamagnetic 8-nm Fe₃O₄ nanoparticles were successfully prepared by chemical oxidation process. For the complex permittivity, the dual dielectric relaxation processes have been proved by two overlapped Cole–Cole semicircles, and the natural resonance frequency is 3.03 GHz for the complex permeability. The maximum reflection loss value reaches −55.5 dB at 6.11 GHz with 3.85 mm in the thickness of the absorbers for the superparamagnetic 8-nm Fe₃O₄ nanoparticles which is better than that of 150 nm and 30 nm Fe₃O₄ nanoparticles. It is believed that the superparamagnetic 8-nm Fe₃O₄ nanoparticles can be used as a kind of candidate for microwave absorber.     

湖北十堰绿松石中杂质矿物自然硒的谱学研究

近期在湖北绿松石市场上出现一种带有肉眼可见的灰黑色异形杂质的绿松石,于此种绿松石的研究甚少.故选取来自湖北省十堰的一块该种绿松石原石,蓝色绿松石基底上布满形态各异、大小不一的灰黑色杂质,放大观察可见灰黑色杂质矿物呈金属光泽.对灰黑色杂质采用激光剥蚀电感耦合等离子体质谱仪进行原位微区微量元素测试、背散射电子图像物相观察、...     

Ultrasound-assisted preparation of ‘Ready-to-use’ extracts from Radix Paeoniae Rubra with natural deep eutectic solvents and neuroprotectivity evaluation of the extracts against cerebral ischemic/ reperfusion injury

Natural deep eutectic solvent (NaDES) is widely applied in the extraction of nutrients from natural resources as a greener alternative for fossil solvent. In the present work, 27 different NaDESs were screened for the extraction of paeoniflorin (PF) and galloyl paeoniflorin (GPF) from Radix Paeoniae Rubra (RPR). After screening and extraction parameter optimization, the extraction yields of PF and GPF reached up to 182.8 mg/g and 77.4 mg/g with the selected NaDES, ChCl-Sor. Furthermore, the antioxidant activity in vitro and neuroprotectivity in vivo of the ‘ready-to-use’ extracts were evaluated comprehensively. Especially in vivo, the cerebral ischemic/ reperfusion injury model was established in rats and the protective effects of the RPR extracts were determined. The results not only proved that NaDES is a valuable green extraction media, but also indicated the safety and potential pharmaceutical application of NaDES based ‘ready-to-use’ extracts from medical plants.     

流动注射-电感耦合等离子体发射光谱法测定天然水中的钙和镁

本文采用流动注射－电感耦合等离子体发现光谱联用技术测定了天然水中的钙、镁元素。考察了试液的雾化和曝光时间及载气压力等因素对分析信号的影响。通过与气动连续进样的对比，测出了钙、镁在流动注射进样下的分散系数。本法在测定钙、镁含量高的水性时，不需对试样进行稀释处理。对五个水样中钙、镁的分析结果与EDTA络合滴定法相吻合。     

自相似结构壳模型

为了扩展以简谐振子为基矢的常规壳模型（ＳＭ）计算到晕核，提出了自相似结构壳模型（ＳＳＭ）．通过对简谐振子动能项和势能项的重度规以及单粒子平均场模拟，可以得到ＳＳＭ中的单粒子轨道有态相关的圆频率，在ＳＳＭ中，晕核大的均方根半径、厚的中子皮以及Ｂｏｒｒｏｍｅａｎ晕核和的束缚态性质能够再现出来。     

用改进的格点哈密顿量计算2+1维QCD 0++胶球质量

用改进的格点哈密顿量和截断本征方程法计算2＋1维QCD 0^ 胶球质量,结果显示较好的标度行为。     

ICP-AES测定饮用天然矿泉水中10种微量元素

ICP- AES直接测定饮用天然矿泉水中 Fe、Pb、Cu、Cr、Cd、Zn、Sr、Ag、Ba、Li10种元素。方法简捷 ,快速 ,准确。相对标准偏差 <5 .4 % ,加标回收率 95 %— 10 5 %。