Direct electrochemistry and electrocatalysis of myoglobin-based nanocomposite membrane electrode

The direct electron transfer of myoglobin (Mb) was achieved based on the immobilization of Mb/Silver nanoparticles (AgNPs) on glassy carbon electrode by multi-wall carbon nanotubes (MWNTs)-chitosan(Chit) film. The immobilized Mb displayed a pair of well-defined and reversible redox peaks with a formal potential (E^θ′) of − 24 mV (vs. Ag/AgCl) in 0.1 M pH 7.0 phosphate buffer solution. The apparent heterogeneous electron transfer rate constants (k_s) of Mb confined to Chit-MWNTs film was evaluated as 5.47 s^{− 1} according to Laviron's equation. The surface concentration (Γ^?) of the electroactive Mb in the Chit-MWNTs film was estimated to be (4.16 ± 0.35) × 10^{− 9} mol cm^{− 2}. Meanwhile, the catalytic ability of Mb toward the reduction of H₂O₂ was studied. Its apparent Michaelis–Menten constant for H₂O₂ was 0.024 mM, showing a good affinity. The linear range for H₂O₂ determination was from 2.5 × 10^{− 5} M to 2.0 × 10^{− 4} M with a detection limit of 1.02 × 10^{− 6} M (S/N = 3). Moreover, the biosensor displays rapid response to H₂O₂ and good stability and reproducibility.     

Numerical simulation of incompressible two‐phase flows with a Boussinesq–Scriven interface stress tensor

We consider the numerical simulation of a three‐dimensional two‐phase incompressible flow with a viscous interface. The simulation is based on a sharp interface Navier–Stokes model and the Boussinesq–Scriven constitutive law for the interface viscous stress tensor. In the recent paper [Soft Matter 7, 7797–7804, 2011], a model problem with a spherical droplet in a Stokes Poiseuille flow with a Boussinesq–Scriven law for the surface viscosity has been analyzed. In that paper, relations for the droplet migration velocity are derived. We relate the results obtained with our numerical solver for the two‐phase Navier–Stokes model to these theoretical relations. Copyright © 2013 John Wiley & Sons, Ltd.     

Oxide‐Supported IrNiOx Core–Shell Particles as Efficient,Cost‐Effective,and Stable Catalysts for Electrochemical Water Splitting

Active and highly stable oxide‐supported IrNiO_x core–shell catalysts for electrochemical water splitting are presented. IrNi_x@IrO_x nanoparticles supported on high‐surface‐area mesoporous antimony‐doped tin oxide (IrNiO_x /Meso‐ATO) were synthesized from bimetallic IrNi_x precursor alloys (PA‐IrNi_x /Meso‐ATO) using electrochemical Ni leaching and concomitant Ir oxidation. Special emphasis was placed on Ni/NiO surface segregation under thermal treatment of the PA‐IrNi_x /Meso‐ATO as well as on the surface chemical state of the particle/oxide support interface. Combining a wide array of characterization methods, we uncovered the detrimental effect of segregated NiO phases on the water splitting activity of core–shell particles. The core–shell IrNiO_x /Meso‐ATO catalyst displayed high water‐splitting activity and unprecedented stability in acidic electrolyte providing substantial progress in the development of PEM electrolyzer anode catalysts with drastically reduced Ir loading and significantly enhanced durability.     

基于MRI影像组学的BI-RADS 3-5类乳腺病变三分类

医生根据磁共振影像征象对患者的乳腺病变程度进行BI-RADS分类评估时存在一定的主观性,且 BI-RADS 3-5类病变的良恶性存在交叉,在临床诊断时极易发生因诊断类别较高而造成不必要的有创治疗．针对这些问题,本文应用影像组学技术对乳腺的T₁加权（T1W）和动态对比增强（DCE）磁共振图像进行特征提取和融合,采用最小绝对收缩和选择算子（LASSO）算法筛选出各特征集的最优特征集,并分别使用支持向量机（SVM）、随机森林（RF）、K最近邻（KNN）及逻辑回归（LR）算法进行BI-RADS 3-5类乳腺病变三分类,并且在此基础上实现乳腺良恶性分类．结果显示基于特征融合的四个影像组学模型对乳腺病变BI-RADS 3-5类的分类准确率分别为81.25%、87.50%、78.38%、81.25%;对乳腺病变良恶性鉴别的准确率分别为90.91%、93.55%、92.73%、94.55%. 这表明MRI影像组学结合机器学习的算法对乳腺病变BI-RADS分类效果及良恶性鉴别效果均较好,且特征融合可进一步提高分类预测的准确率．     

O2在Mo(001)表面吸附的第一原理研究

采用第一原理方法计算了O2分子在 Mo(001) 表面的吸附,得到了吸附构型的各种参数,并且计算了O2分子在 Mo(001) 表面4个位置（顶位,桥位,穴位垂直,穴位平行）吸附后的能量,结果表明在顶位吸附能最高。通过对O2分子在 Mo(001) 表面吸附的原子轨道电荷分布与态密度图的分析可以看出在吸附过程中主要是O原子的2p轨道电子与钼的4s和4d轨道电子的相互作用。     

Effect of negative substrate bias on HWCVD deposited nanocrystalline silicon (nc-Si) films

The influence of the negative substrate bias on the interfacial and microstructural characteristics of nanocrystalline silicon (nc-Si) thin films was deposited by hot wire chemical vapor deposition (HWCVD). Structural characterization of nc-Si films was performed by small angle X-ray diffraction (SAXRD), Raman spectroscopy, X-ray reflectivity (XRR) and field emission scanning electron microscopy (FESEM). Crystalline fraction and crystallite size increases from 61.31 to 74.13% and 13.3 to 21.6 nm, respectively, with an increasing negative bias from 0 to ?200 V. Furthermore, the deposition rate of nc-Si films increases from 25 to 68 nm/min by increase of negative substrate bias from 0 to ?200 V.     

Photosensitizers containing the 1,8-naphthyridyl moiety and their use in dye-sensitized solar cells

Using a Friedl?nder condensation approach, we prepared a series of 2-(pyrid-2'-yl)-1,8-naphthyridines containing a carboethoxy group appended at the 4- and 4'-positions. Complexation of these ligands with Ru(II) and NaNCS led to the complexes [Ru(L)2(NCS)2], and subsequent hydrolysis of the ester groups afforded the carboxylic acid dyes 13b-15b. The more delocalized and electronegative nature of the 1,8-naphthyridyl moiety lowers the energy of the ligand pi*-level and extends the absorption envelope of these complexes well into the red. The system lacking a 4-carboxypyridine moiety shows poor absorbance in the blue region of the spectrum. Solar cells involving thin films of anatase TiO2 impregnated with these dyes were prepared, and their photovoltaic performance was evaluated. The incident photon-to-current efficiencies in the region beyond 625 nm were considerably greater than those of the prototype N3 dye.     

Sarabia洛伦兹曲线模型的推广

本文推广了文献(Sarabia J,Castillo E,Slottje D J.An ordered family of Lorenz curves[J].Journal of Econometrics,1999,91:43-60)中提出的有关洛伦兹曲线模型构造方面的一个定理,在此基础上,对其中提出的一种洛伦兹曲线模型进行了改进和推广,最后的数值试验说明新模型拟合效果远优于前人提出的模型.