Solubility of nano-sized metal oxides evaluated by using in vitro simulated lung and gastrointestinal fluids: implication for health risks

The solubility of nano-sized metal oxides (nZnO, nCuO, nTiO₂, nCeO₂, and nFe₃O₄, 17–42 nm) and some non-nano-mineral powders (ZnO, ZnSiO₃, ZnS, and CuO) were evaluated by using gastrointestinal solubility bioavailability research consortium (SBRC), in vitro gastrointestinal (IVG) method, pulmonary artificial lysosomal fluid (ALF), and Gamble solution method, respectively. It is found that these nano-sized metal oxides aggregated more or less when suspending in the simulated biological fluids analyzed by dynamic light scattering (2 mg L^?1) and UV-Vis spectrometry (100 mg L^?1). The aggregation and sedimentation of nano-metal oxides in a simulated biofluid are influenced by its surface property and the ingredient of the liquid. The dissolution in fluids may decrease the aggregating radius of a nano-metal oxide. In return, the aggregative effect can influence the solubility of metal elements and result in their weakened bioaccessibility. The suspending stability was consistent in the order of nFe₃O₄ < nCuO < nTiO₂ < nCeO₂ < nZnO in all the simulated biological fluids. Nano-ZnO and nCuO showed higher gastrointestinal and pulmonary bioaccessibility than nFe₃O₄, nTiO₂, and nCeO₂. The further comparisons on the bioaccessibility for nCuO and nZnO with non-nano-powder CuO and ZnO indicated that the aggregating size in suspension could play more important role in influencing the bioaccessibility than single particle size does. The present study reveals that aggregation of all studied nano-sized metal oxides occurred in body physiologic fluids and that nZnO and nCuO were easily dissolved in simulated physiologic fluids, suggesting more potential health risks from nZnO and nCuO’s exposure.

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Graphical abstract Aggregation and sedimentation of nano-sized metal oxides with its bioaccessibility: a hint to health risks

     

Impurity effects on ionic-liquid-based supercapacitors

Small amounts of an impurity may affect the key properties of an ionic liquid and such effects can be dramatically amplified when the electrolyte is under confinement. Here the classical density functional theory is employed to investigate the impurity effects on the microscopic structure and the performance of ionic-liquid-based electrical double-layer capacitors, also known as supercapacitors. Using a primitive model for ionic species, we study the effects of an impurity on the double layer structure and the integral capacitance of a room temperature ionic liquid in model electrode pores and find that an impurity strongly binding to the surface of a porous electrode can significantly alter the electric double layer structure and dampen the oscillatory dependence of the capacitance with the pore size of the electrode. Meanwhile, a strong affinity of the impurity with the ionic species affects the dependence of the integral capacitance on the pore size. Up to 30% increase in the integral capacitance can be achieved even at a very low impurity bulk concentration. By comparing with an ionic liquid mixture containing modified ionic species, we find that the cooperative effect of the bounded impurities is mainly responsible for the significant enhancement of the supercapacitor performance.     

Sliding-mode control of switched delay systems with nonlinear perturbations: average dwell time approach

This paper investigates the robust sliding-mode control (SMC) problem for a class of uncertain switched systems with a time delay. The design process of sliding-mode control is divided into two steps. First, a sliding surface is constructed such that the reduced-order equivalent sliding mode restricted to the sliding surface is completely invariant to all admissible uncertainties under switching laws with an average dwell-time property. Second, variable structure controllers are developed to drive the states of the switched delay system to reach the sliding surface in finite time and remain on it thereafter. Finally, a numerical example is given to illustrate the effectiveness of the proposed method.     

The hysteresis loops of a ferroelectric bilayer film with surface transition layers

Based on the transverse Ising model in the framework of the mean field approximation,this paper discusses a ferroelectric bilayer film with the surface transition layers within each constituent slab and an antiferroelectric interfacial coupling between two slabs.The hysteresis loop of a bilayer film is investigated.The results show that the surface transition layer in a ferroelectric bilayer film plays a significant role in realizing the multiple-state memory.     

Particles in composite polymer electrolyte for solid-state lithium batteries:A review

Solid-state lithium batteries(SSLBs)have been identified as one kind of the most promising energy conversion and storage devices because of their safety,high en...     

Effect of Co on the thermal stability and impact toughness of sintered Nd–Fe–B magnets

The effect of Co on the thermal stability and impact toughness of sintered Nd–Fe–B magnets has been investigated. The results showed that the addition of Co decreased the intrinsic coercivity and the temperature coefficient of remanence (α), and increased the temperature coefficient of coercivity (β) for sintered Nd–Fe–B magnets. The impact toughness of sintered Nd–Fe–B magnets with the addition of Co first decreases, reaches a minimum, and then starts to increase. The possible reasons for increasing the temperature coefficients of coercivity (β) for sintered Nd–Fe–B magnets were analyzed, and the relations between the microstructure and impact toughness of sintered Nd–Fe–B magnets were studied.     

纳米氮化硼在吡啶热条件下的物相转变规律

为了研究纳米氮化硼在溶剂热条件下的物相转变规律, 利用三氯化硼(BCl3)和氮化锂(Li3N)为原料, 吡啶作为溶剂合成了纳米氮化硼. 在实验过程中, 系统研究了反应温度、压力以及反应时间的影响, 发现在吡啶热反应体系中, 首先形成的是结构无序的无定形纳米氮化硼(aBN). 随着反应温度和压力的提高以及时间的延长, 纳米氮化硼中的原子排列有序度不断提高, 逐渐出现了结构部分有序的湍层氮化硼(tBN)和结构有序的六方氮化硼(hBN). 在反应温度和压力提高时, 样品中首先是tBN的含量提高, 然后是hBN的含量明显增加, 说明在合成反应过程中存在aBN→tBN→hBN的物相转变.     

Synthesis,Electrochemical, and Optical Properties of a Novel PPV/PPE Block‐Copolymer

Summary: A novel poly(p‐phenylene vinylene) (PPV)/poly(p‐phenylene ethynylene) (PPE) block‐copolymer was synthesized by a cross‐coupling polycondensation with Pd(PPh₃)₂Cl₂ and a phase‐transfer catalyst, and was confirmed by ¹H NMR and IR spectroscopy and elemental analysis. The thermal, electrochemical, and photoluminescent properties of the new copolymer have been investigated. The incorporation of triple bonds into the cyano‐substituted PPV (CN‐PPV) backbone leads to higher oxidation and reduction potentials than poly(2‐methoxy‐5‐(2‐ethylhexyloxy)‐p‐phenylene vinylene) (MEH‐PPV) and CN‐PPV, potentially making the copolymer a good electron‐transporting material for use in a light‐emitting‐diode device.

The cyclic voltammogram of the novel poly(p‐phenylene vinylene) (PPV)/poly(p‐phenylene ethynylene) (PPE) block‐copolymer synthesized here.     

一般单调变分不等式的一个改进的预估-校正算法

最近何炳生等提出了解大规模单调变分不等式的一种预估-校正算法,然而,这个方法在计算每一个试验点时需要一次投影运算,因而计算量较大．为了克服这个缺点,我们提出了一个解一般大规模g-单调变分不等式的新的预估-校正算法,该方法使用了一个非常有效的预估步长准则,每个步长的选取只需要计算一次投影,这将大大减少计算量．数值试验说明我们的算法比最新文献中出现的投影类方法有效．     

Seismic responses for multi-storeyed buildings composed of nonorthogonal members under bi-directional horizontal earthouake ground motions

This paper presents a method for analyzing both linear and nonlinear seismic responses of multistoreyed buildings composed of nonorthogonal structural members under the action of bi-directional horizontal earthquake waves. Different kinds of restoring force model are used. An efficient computer programme for the computation of nonlinear seismic response of the structure was worked out. In order to illustrate the application of this method, an example of a ten-storeyed building of such sort is given.