Synthesis of salicylaldehyde Schiff base modified Cu nanocrystals by thermal treatment in liquid paraffin

Cuboid copper nanocrystals were synthesized by thermal treatment in liquid paraffin without any inert gas protection with salicylaldehyde Schiff base copper (II) (Cu (II)-Salen) complex as precursor. Liquid paraffin was used as solvent and reductant. The obtained copper nanocrystals are morphology-controlled and stable when exposed to air for one year. The nanocrystals were characterized by X-ray diffraction measurements (XRD), UV-visible spectroscopy (UV-vis), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT-IR). The results showed that the stable cuboid copper nanocrystals are synthesized by using Salen as capping agents.     

Rapid microwave-assisted synthesis and electrochemical characterization of gold/carbon nanotube composites

Hybrid nanostructures composed of gold nanoparticles (NPs) and carbon nanotubes (CNTs) have been prepared by a microwave-assisted method in the mixed solvents of oleylamine and oleic. The morphology, structure and composition of as-obtained Au/CNT composites are characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD). The composites show characteristic plasmon absorption of Au NPs in the Ultraviolet–visual spectrum. Fourier transform infrared spectrum shows the successful introduction of functional groups on the surface of CNTs, which are crucial factors to assist the nucleation in situ of Au NPs on the surface of CNTs. Electrochemical measurements show the enhancement electrochemical response for the gold electrode modified with Au/CNT composites.     

Marangoni effect induced micro/nano-patterning on Sb<Subscript>2</Subscript>Te<Subscript>3</Subscript> phase change thin film by laser pulse

Thermocapillary and chemicapillary effects are known to coexist in a material molten pool when irradiated by a pulse laser. According to the effects, we fabricate various patterns with different shapes on a Sb₂Te₃ phase change thin film by precisely adjusting the pulse energy. In this process, the laser power is fixed at 5.0 mW, and the pulse width is adjusted from 100 ns to 5 ns. The shape of the patterns gradually changes from a dimple-bowl shape, a dome shape, a “Sombrero” shape to a deep-bowl shape following an increase in the pulse energy, which corresponds to the crystallization-threshold, bump-threshold, rupture-threshold, and ablation-threshold of the material. The different patterns are the results of the competition between the thermocapillary and chemicapillary effects in the molten pool, which determine the nature of the flow and lead to the different patterns in different laser parameters.     

Synthesis of biodiesel over ZnO/Ca(OH)2/KF catalyst prepared by the grinding method

A novel ZnO/Ca(OH)₂/KF solid base catalyst was prepared by the grinding method and applied to biodiesel synthesis by the transesterification of soybean oil. The effect of various parameters such as KF molar amount, calcination temperature, the amount of catalyst, molar ratio of methanol to oil, reaction temperature, and time on the activity of the catalyst were investigated. The catalysts were characterized by several techniques of thermogravimetry/derivative thermogravimetry, X–ray diffraction, Hammett indicator method, and scanning electron microscopy. The analysis results indicated that the KF interacted with Ca(OH)₂ and formed KCaF₃ phase before calcination of the catalyst. The formed KCaF₃ crystal phase was the main catalytic active component for the catalyst activity. In addition, the basicity of ZnO/Ca(OH)₂/KF was greatly influenced by the different calcination temperates, and the catalyst activity was correlated closely with the basicity. A desired biodiesel yield of 97.6 % was obtained at catalyst amount of 3 %, methanol/oil of 12:1, and reaction time of 1.5 h at 65 °C.     

PbO<Subscript>2</Subscript>-SnO<Subscript>2</Subscript> composite anode with interconnected structure for the electrochemical incineration of phenol

A PbO₂-SnO₂ composite anode with interconnected structure is prepared for organics electro-incineration through a two-step method, thermal-decomposition process and subsequent low-current density electrodeposition process. The element mapping, together with the impedance spectra of the composite electrode, confirms that an interconnected architecture of SnO₂ and PbO₂ grains, instead of a lamellar structure, was obtained on the Ti substrate. A lower electrodeposition current density (≤10 mA cm⁻²) is very crucial for the formation of a porous surface and an interconnected architecture of two oxides inside. The asprepared electrode exhibits an enhanced electrocatalytic activity on the mineralization of phenol and a long service life due to the interconnected architecture, which helps to utilize the merits of these two metal oxides simultaneously. This two-step method also provides us a novel and facile way to fabricate a series of composite material such as oxide-oxide, oxide-metal composite electrodes.     

Design of Sensitive Biocompatible Quantum‐Dots Embedded in Mesoporous Silica Microspheres for the Quantitative Immunoassay of Human Immunodeficiency Virus‐1 Antibodies

A novel sandwich‐type electrochemiluminescence (ECL) immunosensor was developed to enable the sensitive detection of HIV‐1 antibodies. This system incorporated mesoporous silica (mSiO₂) complexed with quantum dots (QDs) and nano‐gold particles, which were assembled to enhance signal detection. Magnetic beads were used by immobilizing the secondary anti‐IgG antibody. This was first employed to capture HIV‐1 antibody (Ab) to form a Fe₃O₄/anti‐IgG/Ab complex. A high loading and signal‐enhanced nanocomposite (hereafter referred to as Au‐mSiO₂‐CdTe) was used as a HIV‐1 antigen label. The Au‐mSiO₂‐CdTe nanocomposite was conjugated with the Fe₃O₄/anti‐IgG/Ab complex to form an immunocomplex (hereafter referred to as Fe₃O₄/anti‐IgG/Ab/HIV‐1/CdTe‐mSiO₂‐Au). This complex could be further separated by an external magnetic field to produce ECL signals. Due to the large specific surface area and pore volume of mSiO₂, the loading of the CdTe QDs was markedly increased. Thus, the loaded QDs released a powerful chemiluminescent signal with a concordantly increased sensitivity of the immunosensor. The immunosensor was highly sensitive, and displayed a linear range of responses for HIV‐1 antibody across a dilution range of 1 : 1500 through 1 : 50 with the detection limit of 1 : 4500. The immunoassay can be a promising candidate in early diagnosis of HIV infection.     

Distributed predictive control of spiral wave in cardiac excitable media

In this paper, we propose the distributed predictive control strategies of spiral wave in cardiac excitable media. The modified FitzHugh--Nagumo model was used to express the cardiac excitable media approximately. Based on the control-Lyapunov theory, we obtained the distributed control equation, which consists of a positive control-Lyapunov function and a positive cost function. Using the equation, we investigate two kinds of robust control strategies: the time-dependent distributed control strategy and the space-time dependent distributed control strategy. The feasibility of the strategies was demonstrated via an illustrative example, in which the spiral wave was prevented to occur, and the possibility for inducing ventricular fibrillation was eliminated. The strategies are helpful in designing various cardiac devices. Since the second strategy is more efficient and robust than the first one, and the response time in the second strategy is far less than that in the first one, the former is suitable for the quick-response control systems. In addition, our spatiotemporal control strategies, especially the second strategy, can be applied to other cardiac models, even to other reaction-diffusion systems.     

光束束宽概念和不同定义束宽的比较

对束宽的不同定义作了比较研究.结果表明,不同定义束宽的数值是不同的.在自由空间中传输时,二阶矩束宽遵守ABCD定律,熵束宽的传输曲线近似于双曲线,但环围功率束宽一般不满足ABCD定律.双曲余弦高斯光束按二阶矩束宽和熵束宽法所得焦移几乎相同,而环围功率法所得焦移则与之不同.     

Intrinsic damping for ultrafast laser-excited acoustic vibrations of single gold nanorods

The intrinsic damping for the acoustic vibrations of single gold nanorods excited by ultrafast laser has been studied through the atomistic simulations. It is shown that the intrinsic damping for the breathing mode is strongly sensitive to the nanorod sizes, which is very likely due to the different energy redistributions between the vibrational modes of nanorods and could play a non-negligible role in the broad distribution of the experimentally measured breathing-mode quality factors. In comparison, the intrinsic damping for the extensional vibration of gold nanorods appears much less influenced by the variations of nanorod dimensions. Moreover, we also find that the intrinsic mechanism is a significant source for the vibrational damping of gold nanorods, particularly for the breathing mode.     

Perovskite-type Ba0.5Sr0.5Al0.1Fe0.9O3-δ as Intermediate-Temperature Solid Oxide Fuel Cell Cathode

A cobalt-free perovskite-type Ba_0.5Sr_0.5Al_0.1Fe_0.9O_3-δ (BSAF) is developed and electro-chemically studied as solid oxide fuel cell (SOFC) cathode. The structures, electrical con-ductivity, and electrode polarizations in symmetrical cell based on mixed ion conducting electrolyte were investigated, respectively. The temperature dependence of conductivity of BSAF in air shows a typical semiconductor behavior with positive temperature coefficient up to 450 oC where the conductivity reaches 14.0 S/cm while above this temperature the negative temperature coefficient dominates the total conductivity. Electrochemical charac-terizations show desirable polarization resistance of BSAF cathode in a symmetric cell based on mixed ion conducting electrolyte at 650-700 oC. A single SOFC with BSAF cathode shows OCV of 1.0 V and maximum output of 420 mW/cm₂ at 700 oC with humidified hydrogen fuel and static air oxidant.