Distinct magnetic properties of one novel type of nanoscale cobalt-iron Prussian blue analogues synthesized in microemulsion

One novel type of nanoscale cobalt-iron Prussian blue analogues (PBA) in the form of mixed nanorods and nanocubes were synthesized using cetyltrimethyl ammonium bromide (CTAB) as the surfactant in microemulsion at low temperature. The generated products were characterized by SQUID, XRD and IR techniques, etc. The effects of potassium contents, cobalt-to-iron ratios, reaction temperatures on the properties of the nanoscale cobalt-iron PBA were systematically explored. The results showed that the novel type of nanomaterials possessed distinct magnetic properties in that their coercivities were intensely dependent on cobalt-to-iron ratios and potassium contents. Furthermore, it was observed that low reaction temperature not only affected the morphologies of the products, but also had influence on their magnetic properties. Additionally, the cobalt-iron Prussian blue analogues were strongly influenced by CTAB around their surface, which led to higher Curie temperatures.     

Structural and electronic properties of type-I and type-VIII Ba8Ga16Sn30 clathrates under compression

The total energy and electronic structures for type-I (β phase) and type-VIII (α phase) Ba₈Ga₁₆Sn₃₀ clathrates under hydrostatic pressure have been investigated using density functional theory (DFT) calculations. It was found that the type-VIII phase is more stable than the type-I one at ambient conditions and that β→α phase transition can not occur under hydrostatic pressure. The band structures show that the type-I and type-VIII Ba₈Ga₁₆Sn₃₀ are indirect semiconductors with band gaps of 0.24 eV and 0.19 eV, respectively. The results suggested that type-I clathrate Ba₈Ga₁₆Sn₃₀ has a larger value of the thermoelectric (TE) power than that of type-VIII clathrate. We found that pressure tuning changes the k-point of conduction band minimum (CBM) in the Brillouin zone for β-phase, but it is not the case for α-phase. Furthermore, the results show that the pressure can change the interaction between guest atoms and the host lattice, and consequently results in the decrease of the band gap of β-phase and the increase of the band gap of α-phase, indicating that the pressure effect can play an important role in the magnitude of the TE power.     

Non‐intrusive reduced‐order modeling for multiphase porous media flows using Smolyak sparse grids

In this article, we describe a non‐intrusive reduction method for porous media multiphase flows using Smolyak sparse grids. This is the first attempt at applying such an non‐intrusive reduced‐order modelling (NIROM) based on Smolyak sparse grids to porous media multiphase flows. The advantage of this NIROM for porous media multiphase flows resides in that its non‐intrusiveness, which means it does not require modifications to the source code of full model. Another novelty is that it uses Smolyak sparse grids to construct a set of hypersurfaces representing the reduced‐porous media multiphase problem. This NIROM is implemented under the framework of an unstructured mesh control volume finite element multiphase model. Numerical examples show that the NIROM accuracy relative to the high‐fidelity model is maintained, whilst the computational cost is reduced by several orders of magnitude. Copyright © 2016 John Wiley & Sons, Ltd.     

Real‐Time Measurement of the Size Distribution of Diesel Exhaust Particles using a Portable 4‐stage Electrical Low Pressure Impactor

For this study, a 4 stage electrical low pressure impactor was designed to measure the real‐time size distribution of diesel particulate matter (DPM). For the performance evaluation, sodium chloride (NaCl) particles and dioctyl sebacate (DOS) particles were used. After evaluating the collection efficiency of each stage of the impactor, the size distributions of test particles were estimated using electrical current data and their inversion algorithm, and this was found to agree with the results obtained by a scanning mobility particle sizer (SMPS). For measurement of DPM, a common‐rail direct injection (CRDI) diesel engine, for engine speeds of 1,200 rpm and 1,500 rpm at 2.7 kgf·m, was used. Therefore, it was found that the size distribution of the DPM could be easily obtained, with the currents measured by the impactor and the data inversion algorithm, in less than 5 seconds. Furthermore, the effective density of the DPM could be obtained using the calculated results and the SMPS data.     

带拯救的两参数Markov碰撞过程的遍历性

本文考虑了一类带拯救的两参数Markov碰撞过程.首先讨论了带拯救的两参数Markov碰撞q-矩阵发生函数的性质,通过发生函数给出了过程的正则性和唯一性判别准则,得到了过程的常返性和遍历性的充分必要条件,并给出了几个易于验证的充分条件.最后,给出了遍历情形下该过程平稳分布的发生函数,并给出了过程强遍历的判别准则.     

An Investigation of the Effect of Semi-Acetal Formation on the Properties of Dialdehyde Starch and its Thermoplastic Blend with Glycerol

Dialdehyde sweet potato starch (DASS) with various aldehyde contents was prepared and the properties analyzed in terms of solubility, intrinsic viscosity, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results demonstrated that when the aldehyede content of DASS was increased from 20% to 95%, the solubility, molecular weight, crystallizability, and thermal stability decreased. Thermoplastic DASS (TPDASS) was prepared by adding glycerol as a plasticizer; the thermal, rheological, hydrophobic, and tensile properties of TPDASS were investigated. The results indicated that, for the same glycerol content, with the increase of aldehyde content, the moisture adsorption decreased, while the shear viscosity, glass transition temperature, and tensile properties of TPDASS increased significantly. The effects were attributed to the introduction of aldehyde groups reducing the hydrogen bonds and decreasing the hydrophility of the starch. Moreover, the aldehyde and hydroxyl groups of DASS favored a semi-acetal formation with higher aldehyde content and cross-linking of DASS occurred with the increase of aldehyde content. In summary, compared to starch, the thermoplastic properties and hydrophobicity of DASS was improved. In the presence of water (10 wt%), the tensile strength of TPDASS with 95% aldehyde content (TPDASS95) moderately decreased, from 16.7 MPa to 14.0 MPa, when the glycerol content increased from 10% to 30%. The TPDASS with improved properties will find their applications in preparing biodegradable plastics.     

R~N上具有渐近线性项的奇异椭圆问题的研究（英文）

本文通过变分方法,证明包含Hardy位势的奇异椭圆问题-Δu(x)-μ/|x|2u(x)=K(x)f(u),x ∈RN,x在u∈D1,2(RN)中至少有一个非平凡解,其中N≥3,0≤μ≤∶=((N-2)/2)2,f(t)是在R上的连续函数并且在无穷远处渐近线性.