磁性Ag@Fe3O4@C负载纳米金的制备及其SERS性能

利用一步溶剂热法制备了具有核壳结构的Ag@Fe₃O₄磁性纳米颗粒,然后以葡萄糖作为碳源对Ag@Fe₃O₄进行包覆,再利用酰胺化反应成功的将聚乙烯亚胺（PEI）修饰到Ag@Fe₃O₄@C表面,最后以N-Au共价键的方式将Au纳米粒子组装到Ag@Fe₃O₄@C表面。以4-巯基苯甲酸（4MBA）为拉曼活性探针分子来考察该复合纳米材料的表面增强拉曼（SERS）性能。通过控制Au纳米粒子的加入量,来调节Ag@Fe₃O₄@C-Au复合纳米材料的SERS活性。通过实验测试及利用时域有限差分法（FDTD）得出不同纳米金用量包覆的Ag@Fe₃O₄@C磁性纳米颗粒对4MBA的SERS效果依次为Ag@Fe₃O₄@C-Au-40 > Ag@Fe₃O₄@C-Au-10 > Ag@Fe₃O₄@C-Au-60 > Ag@Fe₃O₄@C,其中Ag@Fe₃O₄@C-Au-40的饱和磁化强度为411 A·g^-1,其对4MBA的检测限为1×10^-9 mol·L^-1。这种功能性复合材料既具有良好的SERS活性,又可通过外加磁场的方式实现对待测分子的分离、富集。     

基于四(3-吡啶氧亚甲基)甲烷及氰化铜螺旋链手性金属有机骨架化合物的合成及其性质研究

通过一个非手性配体和1D氰化铜链螺旋成功构建了一种新型的手性金属有机骨架:[Cu₄(CN)₄(L)₂]_n (1,L=四(3-吡啶氧亚甲基甲烷));铜(Ⅰ)和原位生成的氰基组装而生成的螺旋是左旋并且它使得金属有机框架具有手性。这是首例通过半刚性四面体配体多变的构像诱导合成独特的手性金属有机骨架化合物。此外还研究了该化合物的手性、热稳定性以及介电性质。     

求解对流扩散方程的四种差分格式的比较

利用对流扩散方程，在边界和参数存在随机扰动的情况下，考察四种差分格式的优劣，为求 解对流扩散方程提供一种可靠的差分格式，并得到通过空间加密网格的方法可以控制边界、 参数随机影响的结论. 关键词： 对流扩散方程 差分格式 随机扰动     

Thermal formation of mixed-metal inorganic complexes at atmospheric pressure

Atmospheric-pressure thermal desorption ionization (APTDI), a new variant on older ionization methods, is employed to generate gas-phase ions from inorganic and organometallic compounds. The method is compared to conventional electrospray ionization (ESI) of these compounds and found in most cases examined to yield simpler mass spectra which are useful in the characterization of the pure compounds. Cluster formation, however, is prominent in these spectra and mixtures of V(IV)O(salen), Ni(II)(salen) and Co(II)(salen) show mixed-metal cluster ions. This makes APTDI a way to prepare gas-phase ions which contain multiple selected metal atoms and ligands. Such mixed-metal complexes can be mass-selected and structurally characterized by tandem mass spectrometry. Strong contrasts are evident in the dissociation behavior of homonuclear and heteronuclear metal clusters, the latter showing accompanying redox processes. The chemical reactivity accompanying collision-induced dissociation (CID) of some of the mixed-metal clusters is typified by the protonated species H+[NiVO(salen)], which undergoes a formal oxidation process (hydrogen atom loss) to give the molecular radical cation of Ni(salen). This ionization method may provide a new route to unique inorganic compounds on surfaces through soft landing of appropriate cluster ions. The contrasting behavior of the ESI and APTDI processes is evident in the salens where ESI shows simple Bronsted acid/base chemistry, no mixed-metal clusters and no redox chemistry.     

2′-(4-氟基苯亚甲基)-3，5-二羟基苯甲酰腙Ni(Ⅱ)配合物的合成、表征、晶体结构及光谱性质

In ethanol, a new mononuclear nickel(Ⅱ) complex incorporating Schiff base ligands, [NiL₂](DMF)₄ (HL=2′-(4-fluorobenzylidene)-3,5-dihydroxybenzoylhy drazide) has been synthesized and characterized by IR, UV-Vis, elemental analysis and X-ray crystal structure analysis. The single crystal structure has been determined by single-crystal X-ray diffraction structure analysis. The crystal belongs to monoclinic system, space group P2₁/c with a=1.617 3(2) nm,b=1.798 5(2) nm, c=0.737 61(10) nm, β=91.953(3)°, V=2.144 3(5) nm³, Z=2, μ=0.526 mm^-1, D_c=1.390 g·cm^-3, F(000)=940, R_int=0.105 3. In the compound nickel(Ⅱ) atom is four-coordinated with two nitrogen atoms from amide and two oxygen atoms from keto group. The complex has the centrosymmetry and the nickel(Ⅱ) ion is located in the center. CCDC: 675522.     

一种用于光催化氧化硫醚成亚砜的超薄卟啉的共价有机骨架纳米片

单线态氧(~1O_2)可将硫醚化合物选择性氧化为亚砜,而开发具有高~1O_2量子产率的高效光敏剂至关重要。本文中我们报道了超薄二维共价有机骨架(COFs)纳米片(NSs)COF-367 NSs的制备和表征。COF-367 NSs在各种有机溶剂中的良好分散性和高效率的光收集赋予其在可见光照射下产生~1O_2的显著性能,且远优于块体COF-367。我们还证明了COF-367 NSs是硫醚化合物光催化氧化成亚砜的优良非均相催化剂,具有高效率和选择性以及良好的循环稳定性。     

热辅助存储磁盘硅掺杂非晶碳薄膜氧化的ReaxFF反应力场分子动力学模拟

Heat-assisted magnetic recording (HAMR) is one of the promising ways to extend the magnetic recording area density to 1 Tb·in^-2 in hard disk drives (HDDs).High temperature induced by laser heating can cause carbon overcoat (COC) oxidation.Reactive molecular dynamics (MD) simulations are performed to investigate the oxidation process of silicon-doped amorphous carbon (a-C:Si) films for HAMR application.The atomic details of the structure evolution and oxidation process are investigated, and, the oxidation mechanism of the a-C:Si film is clarified.The effect of the duration of laser irradiation on the oxidation of the a-C:Si film is investigated.The oxidation occurs during heating and the beginning of cooling process.Both volume expansion during heating process and cluster of carbon atoms during cooling process increase the rate of sp² carbon.Because of the decrease in the amount of unsaturated silicon atoms and low diffusion coefficient of atomic oxygen, the oxidation rate of the a-C:Si film decreases with laser irradiation cycles.The molecular oxygen is the oxidant due to surface defect of a-C:Si film.The atomic strains break the O-O bonds in Si-O-O-Si linkages and rearrange the surface oxide layers, and process the oxidation of the a-C:Si film.     

Molecular dynamics simulation of the structural evolution of misfit dislocation networks at γ/γ′ phase interfaces in Ni-based superalloys

The structural evolution of misfit dislocation networks at γ/γ′ phase interfaces in Ni-based single crystal superalloys under tensile loading and temperatures is simulated by molecular dynamics. From the simulation, we find that, with increasing load or temperature, the patterns of dislocation networks on the (100), (110) and (111) phase interfaces change from regular to irregular or disappear. Under the same load and temperature, the dislocation networks of the different phase interfaces show different degrees and patterns of damage. The density and stability of the dislocation networks decrease with increasing temperature. When the interfacial dislocation networks become more regular, the γ/γ′ interfaces become more stable. The simulated results are supported by related experimental findings. Moreover, based on MD simulations, the averaged stress–strain responses for different phase interfaces under loading are presented. The results indicate that the combined influences of temperature and load play an important role for the structure evolution of misfit dislocation networks at γ/γ′ phase interfaces of Ni-based superalloys.     

基于偏态分布的百分位估计公式的建立

顺序统计量将累积概率与数据排序后的位置建立相关联系,可用于估计数据分布的累积概率.鉴于不同气候要素概率分布存在着不同程度的偏态特征,基于偏态分布条件下的累积概率函数,通过理论推导和数值模拟建立了与偏态指数相关的位置参数的回归模型,从而给出了基于数据偏态特征的经验百分位估计公式.利用1980年-2009年全球夏季逐日平均温度资料,进一步对比分析了偏态百分位估计方法与Jenkinson方法下得到的第90个百分位值所对应的温度排序后位置的差异. 关键词： 顺序统计量 偏态分布 百分位     

不同滤波方法在去趋势波动分析中去噪的应用比较

研究了连续噪声和尖峰噪声对去趋势波动分析的影响,发现噪声的存在使得双对数曲线在尺度较小时发生了"转折"现象.针对这一问题,文中采用三种不同滤波方法对理想时间序列进行了实验,结果表明,多级Vondrak滤波得到的高频序列与真实噪声序列无论是在强度还是在演变趋势上都展现出惊人的一致性,低频滤波序列的去趋势波动分析结果与真实信号十分接近,多级Vondrak滤波基本上能够消除由于噪声所引起的"转折"现象,而且这一研究结果对于滤波周期阈值的依赖性并不太大.多点滑动加权平均滤波虽然能够在一定程度上减轻噪声对于去趋势波动的影响,但不能从根本上消除由于噪声所引起的"转折"现象.快速傅里叶滤波在选择合适的滤波周期阈值时,能够基本消除噪声对去趋势波动分析的影响,但是由于其滤波结果对于滤波周期阈值的依赖较大,在实际应用中滤波周期阈值的选取比较困难.因此,多级Vondrak滤波是消除噪声对去趋势波动分析结果影响的一种有效的途径. 关键词： 多级Vondrak滤波 去趋势波动分析 多点滑动加权平均滤波 快速傅里叶滤波