离子色谱-氢化物发生原子荧光光谱联用技术在砷形态分析中的应用

建立了离子色谱-氢化物发生原子荧光光谱联用分离4种常见有毒砷化合物的方法. 二者通过内径0.25 mm的PEEK管直接相连. 实验对影响分离度和测定灵敏度的参数进行了优化. 在优化条件下, 质量浓度均为50 μg/L的4种砷化合物混合标准溶液平行7次进样, 得到DMA、 As(Ⅲ)、 MMA和As(Ⅴ)的色谱峰面积的相对标准偏差(RSD)为2.8～3.0%. 250 μL进样的线性范围为5～1000 μg/L, 检出限为0.8～1.2 μg/L (三倍基线噪音峰高). 用建立的方法测定了砷处理后的水稻木质部伤流液中的砷量, 4种砷化合物的加标回收率为89%～105%. 该装置接口简单, 方法分离度好, 灵敏度高, 可用于实际样品中痕量砷化合物的形态分析.     

Transport properties of boron nanotubes investigated by ab initio calculation

We investigate atomic and electronic structures of boron nanotubes (BNTs) by using the density functional theory (DFT). The transport properties of BNTs with different diameters and chiralities are studied by the Keldysh nonequilibrium Green function (NEGF) method. It is found that the cohesive energies and conductances of BNTs decrease as their diameters decrease. It is more diffcult to form (N,0) tubes than (M,M) tubes when the diameters of the two kinds of tubes are comparable. However, the (N,0) tubes have a higher conductance than the (M,M) tubes. When the BNTs are connected to gold electrodes, the coupling between the BNTs and the electrodes will affect the transport properties of tubes significantly.     

聚氨酯／聚丙烯酸酯复合涂料的新进展

本文综述了近年来聚氨酯／聚丙烯酸酯复合涂料的新进展，主要介绍了合成方法、特点及几类新型的涂料体系，并对该领域进一步的发展提出了看法。     

关于κ-广义酉矩阵

本文研究了κ-广义酉矩阵的性质及其与酉矩阵、辛矩阵、Householder矩阵之间的联系，取得了许多新的结果，推广了酉矩阵及Householder矩阵的相应结果，特别将正交矩阵的广义Cayley分解推广到了广义酉矩阵上；并将各类酉矩阵及辛矩阵统一了起来．     

超高效液相色谱-电喷雾串联质谱法同时分析鸡肉中7种氟喹诺酮类药物残留

建立了一种同时测定鸡肉中7种氟喹诺酮类药物残留的超高效液相色谱-电喷雾串联质谱确证分析方法(UPLC-ESI-MS/MS)。样品经酸化乙腈提取、正己烷脱脂和HLB固相萃取柱净化,采用ACQUITY UPLCTM BEH C18色谱柱(50 mm×2.1 mm,1.7 μm)分离,以0.1%甲酸水溶液和乙腈作为流动相进行梯度洗脱,电喷雾质谱检测,正离子多反应监测模式进行定性和定量分析。7种药物在5～100 μg/kg范围内线性关系良好,相关系数(r2)均大于0.99;以5,25,50 μg/kg3个浓度水平进行添加回收试验,7种药物的平均回收率在79.2%～108.6%之间,相对标准偏差为4.2%～8.9%,方法的检出限(LOD)为0.2～1.4 μg/kg。方法重现性好、灵敏度高、分析时间短、确证能力强,适用于鸡肉中氟喹诺酮类药物多残留的确证检测。     

Fe基非晶纳米晶电弧喷涂层的摩擦学性能

采用自动化高速电弧喷涂技术在AZ91镁合金基体上制备了FeCrBSiMnNbW非晶纳米晶涂层.研究了涂层材料在干摩擦条件下的摩擦学性能.采用配备有能谱分析仪（EDAX）的扫描电子显微镜（SEM）和X射线衍射仪（XRD）对涂层的微观组织结构进行了表征.采用显微硬度计和纳米压痕仪对涂层的力学性能进行了分析,摩擦磨损试验在UMT-2型摩擦磨损试验机上进行,并采用三维白光干涉表面形貌仪（Phase Shift MicroWAM-3D）测定磨损量.结果表明：涂层组织均匀、结构致密、氧化物含量低,涂层主要由非晶相和纳米晶相组成;涂层具有较高的硬度和弹性模量;在相同的试验条件下,非晶纳米晶合金涂层的相对耐磨性是传统3Cr13涂层的3倍;磨损机制主要为典型的脆性剥落.     

Low-Dimensional Forest-Like and Desert-Like Fractal Patterns Formed in a DDAN Molecular System

Two kinds of forest-like and desert-like patterns are formed by thermal evaporation of 4-dicyanovinyl-N, Ndimethylamino-1-naphthalene （DDAN） onto SiO2 substrates. Based on thermal kinetics of the molecules on the substrate the transformation between the forest and desert patterns is due to two factors. The first one is the diffusion length, which is related to the deposition rate, the diffusion potential energy barrier and the substrate temperature. The second one is the strong interaction between the two polarity chemical groups of the molecules, which is beneficial to the formation of branches. Totally different patterns are also found on mica substrates, and are attributed to the anisotropic diffusion and the stronger interaction between DDAN molecules and the mica surface.     

储备池状态空间重构与混沌时间序列预测

分析了现有的基于回声状态网络(ESN)的迭代预测方法，指出了该方法在理论上存在的问题以及应用中存在的障碍.提出了一种基于储备池的直接预测方法，该方法利用预测原点和预测时域之间的关系直接构建预测器，因此可以预先对预测器的稳定性施加约束，从而避免了在迭代预测方法中由于网络回路闭合而产生的稳定性问题.在仿真中，首先以Lorenz时间序列为例分析了迭代预测方法在闭合回路前后储备池的变化情况，然后通过Mackey-Glass标杆问题的测试验证了直接预测方法的可行性.     

Spin and spin-orbit coupling effects in nickel-based superalloys: A first-principles study on Ni3Al doped with Ta/W/Re

Heavy elements(X=Ta/W/Re)play an important role in the performance of superalloys,which enhance the strength,anti-oxidation,creep resistance,and anti-corrosiveness of alloy materials in a high-temperature environment.In the present research,the heavy element doping effects in FCC-Ni(γ)and Ni₃Al(γ')systems are investigated in terms of their thermodynamic and mechanical properties,as well as electronic structures.The lattice constant,bulk modulus,elastic constant,and dopant formation energy in non-spin,spin polarized,and spin-orbit coupling(SOC)calculations are compared.The results show that the SOC effects are important in accurate electronic structure calculations for alloys with heavy elements.We find that including spin for bothγandγ'phases is necessary and sufficient for most cases,but the dopant formation energy is sensitive to different spin effects,for instance,in the absence of SOC,even spin-polarized calculations give 1%to 9%variance in the dopant formation energy in our model.Electronic structures calculations indicate that spin polarization causes a split in the metal d states,and SOC introduces a variance in the spin-up and spin-down states of the d states of heavy metals and reduces the magnetic moment of the system.