Photothermal effect for Fe3O4 nanoparticles contained in micelles induced by near-infrared light

Near infrared (NIR) light induced photothermal effect for Fe₃O₄ nanoparticles, contained in Pluronic F127 micelles, has been studied and it exhibits high photothermal converting efficiency. Heat is found to be rapidly generated in micelles containing Fe₃O₄ nanoparticles by NIR laser irradiation. Upon irradiation at 808 nm light and with mass concentration of Fe₃O₄ nanoparticles in 4 g/L, the micelle temperature increase is higher than 34°C for 10min irradiation. The maximum temperature of micelles containing Fe₃O₄ nanoparticles in 4 g/L reaches 62°C.     

Gain and noise figure analysis of Er<Superscript>3+</Superscript>-doped YAG transparent ceramic microchip amplifier

The rate equations and the power evolution equations based on excited state absorption (ESA) and cooperative upconversion (CUC) of high concentration erbium-doped yttrium aluminum garnet (YAG) transparent ceramic waveguide amplifier are set up to analyze the effects of the pump power, active ion concentration and waveguide length on the amplifier gain and noise figure (NF). The numerical analysis predicts that with a pump power of 100mW, an active ion concentration of 1.0×10²⁶ ion/m³ and a waveguide length of 3 cm, a small-signal gain of 30 dB and an NF of 5 dB can be achieved in the micro-chip amplifier.     

Research on reduction of Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> by biomass sawdust

The research on biomass reduction of Fe₂O₃ was carried out by using sawdust as reductant. The direct reducing agents in the biomass magnetization process were determined by comparing various biomass pyrolysis products with the reduction degree (divalent iron content in total iron), reduction temperature range and valence change of Fe₂O₃ in the reduction process. The microstructure variation of Fe₂O₃ at different stages was also analyzed by scanning electron microscopy (SEM). Nonisothermal thermogravimetric analysis (TGA) was applied to explore the thermal reduction process. The results show that the direct reducing substances in the biomass reaction with Fe₂O₃ are H₂ and bio-oil, and the reduction process can be divided into two steps: biomass pyrolyzing to release H₂ and bio-oil, and reductive volatiles reacting with Fe₂O₃. The two steps are relatively independent. The kinetic of the reduction reaction follows a first-order reaction kinetic model, with 88.99 kJ/mol activation energy and 9.55 × 10⁸ min^?1 frequency factor.     

Effect of oxygen content on structural and optical properties of single Cu2O film by reactive magnetron sputtering method

Cuprous oxide (Cu₂O) thin films have been deposited on glass substrate by reactive magnetron sputtering method using Cu target and argon oxygen gas atmosphere. Effect of oxygen flow rate on structural and optical properties of thin films has been discussed. The results of X-ray diffraction, ultraviolet-visible spectrophotometry and atomic force micrograph indicated that the condition window for single Cu₂O phase was about 3.8 to 4.4 cm³/min, and the optimum oxygen flow rate was 4.2 cm³/min. The optical band gap E _g of Cu₂O film was determined by using the data of transmittance versus wavelength, and slightly decreased from 2.46 to 2.40 eV with the increase of oxygen flow rate from 3.8 to 4.4 cm³/min. The Cu₂O film formed at the oxygen flow rate of 4.2 cm³/min had an optical band gap of 2.43 eV.     

Improvement of immunoassay detection sensitivity by using well-defined raspberry-like magnetic microbeads as carriers

Well-defined raspberry-like magnetic microbeads(RMMBs) as immunoassay solid carriers were prepared by chemical covalent binding between Fe3O4 magnetic microspheres and SiO2 nanoparticles. These RMMBs were not as agglomerative as nano-sized magnetie particles( 200 nm), which was an advangtage for high efficient magnetic separation. When compared to Fe3O4@SiO2core-shell magnetic microbeads(CMMBs) with smooth surface, RMMBs exhibited stronger capacity to bind biomolecules. Limit of blank(LoB) and limit of detection(LoD) of HBsAg detection using RMMBs as carriers via chemiluminiscence immunoassay(CLIA) were 0.472 and1.022 μg/L, respectively, showing a notable improvement compared with CMMBs whose LoB and LoD were 1.017 and 1.988 μg/L, respectively. All these indicated a great potential of RMMBs in immunoassay application.     

Effect of Cu Co-doping on the magnetism of Zn0.95Co0.05O films

Zn_0.95?x Co_0.05Cu _x O (atomic ratio, x = 0?C8%) thin films are fabricated on Si(111) substrate by reactive magnetron sputtering method. Detailed characterizations indicate that the doped Cu ions substitute the Zn²⁺ ions in ZnO lattice. The doped Cu ions are in +1 and +2 mixture valent state. The ferromagnetism of the Zn_0.95?x Co_0.05Cu _x O film increases gradually with the increase of the Cu⁺ ion concentration till x = 6%, but decreases for higher Cu concentration. Experimental results indicate that the increase of ferromagnetism is not owing to the magnetic contribution of Cu⁺ ions themselves, but owing to the enhancement of magnetic interaction between Co²⁺ ions, which suggests that p-type doping of Cu⁺ ions plays an important role in mediating the ferromagnetic coupling between Co ions.     

Effect of oil shale on Na+ solidification of red mud-fly ash cementitious material

Red mud-fly ash based cementitious material mixed with different contents of oil shale calcined at 700°C is investigated in this paper. The effect of active Si and Al content on the solidification of Na⁺ during the hydration process is determined by using X-ray diffraction (XRD), ²⁷Al and ²⁹Si magic-angle-spinning nuclear magnetic resonance (MAS-NMR), infrared (IR), scanning electronic microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It is shown that the content of oil shale has a remarkable effect on the solidified content of Na⁺. The hydration process generates a highly reactive intermediate gel phase formed by co-polymerisation of individual alumina and silicate species. This kind of gel is primarily considered as 3D framework of SiO₄ and AlO₄ tetrahedra interlinked by the shared oxygen atoms randomly. The negative charges and four-coordinated Al inside the network are mainly charge-balanced by Na⁺. The solidifying mechanism of Na⁺ is greatly attributed to the forming of this kind of gel.     

Microwave hydrothermal synthesis and characterization of ZnO nanostructures in aqueous solution

ZnO nanostructures were prepared in aqueous solution by microwave hydrothermal synthesis. Xray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize ZnO nanostructures (ZNs). The effects of pH, reaction temperature and reaction time on yield of ZnO were investigated. The yield of ZnO increased significantly with the increase of pH value, reaction temperature and reaction time. High yield and well crystallinity of ZNs could be obtained at 120°C for 60min by microwave hydrothermal synthesis. The spherical and rugby-like ZNs were obtained at 120°C without triethanolamine (TEA) and with TEA (mass ratio, $r = m_{Zn^{2 + } }$ : m _TEA = 1: 1), respectively. The concentration of Zn(OH) ₄ ^?2 ions in the reaction solution and TEA had an important effect on the nucleation and morphology of ZnO nanostructures. Mechanism for the formation of ZnO nanostructures was proposed.     

Purification effects of C2Cl6 on A00 aluminum

The effects of several fluxes on purification, microstructures and properties of A00 aluminum have been studied. The experimental results and analyses indicate that many cracks and large porosities exist in the surface film above the melt purified by C₂Cl₆ and that the film is floc and mostly composed of Al₂O₃ and pure aluminum, which carries many carbon particles and AlCl₃ not fully volatilized. And then over 50% (mass fraction) of the all-melting residue is pure aluminum, which is one of the major reasons for high melting loss. Moreover, because of a mass of gas bubbles and a state of seethe, there are many inclusions which size is under 10 ??m in the microstructure of A00 aluminum purified with C₂Cl₆ or fluxes containing C₂Cl₆. With this purifying method, the aluminum crystal grains are extended along the radius that was observed firstly and the average crystal size of A00 aluminum are about 100?C150 ??m. In addition, small size inclusions have little affected on tensile strength and micro inclusions under 10 ??m have little affected on elongation.     

Threshold signature scheme with threshold verification based on multivariate linear polynomial

Secret sharing schemes are multi-party protocols related to key establishment. They also facilitate distributed trust or shared control for critical activities (e.g., signing corporate cheques and opening bank vaults), by gating the critical action on cooperation from t(t ∈ Z ⁺) of n(n ∈ Z ⁺) users. A (t, n) threshold scheme (t < n) is a method by which a trusted party computes secret shares Γ _i (1 ⩽ i ⩽ n) from an initial secret Γ ₀ and securely distributes Γ _i to user. Any t or more users who pool their shares may easily recover Γ ₀, but any group knowing only t−1 or fewer shares may not. By the ElGamal public key cryptophytes and the Schnorr’s signature scheme, this paper proposes a new (t, n) threshold signature scheme with (k,m) (k,m ∈ Z ⁺) threshold verification based on the multivariate linear polynomial.     

Improvements of elevated temperature strength and creep resistance of Mg-12Zn-4Al based alloy with calcium addition

A series of Mg-12Zn-4Al-0.3Mn (ZA124) based alloys with additions of calcium have been prepared and their microstructure and properties have been investigated. The results show that Mg-12Zn-4Al-0.3Mn alloy consists of the ??-Mg matrix and block quasicrystal and exhibits excellent creep resistance compared to commonly used AZ91 alloy. A small amount of calcium addition to the ZA124 based alloys increased the yield strenghth at both ambient and elevated temperatures as well as creep resistance, although the ductility decreased slightly. Microanalysis indicated that the addition of calcium decreased the quasicrystalline phase and caused the formation of some lamellar precipitates of Al₂Mg₅Zn₂ with orthorhombic crystal structure. This Ca-containing Al₂Mg₅Zn₂ phase with high stability straddled the grain boundaries and strengthened grain boundaries by inhibiting crack propagation during creep tests at elevated temperature.     

Safety Evaluation for Freeway Exit Ramp Based on Speed Consistency

Speed differential has direct relationship with road safety. Conventional speed consistency measures draw sample data from independent population that follows a normal distribution. These methods may fall into ecological fallacy and overestimate the safety level of road elements. After deducing the relationship between the difference in operating speed ΔV₈₅ and85(ΔV), the 85^th percentile value of individual speed reduction, this paper recommends 85(ΔV) and speed reduction rate 85(ΔV)R is used to evaluate ramp safety. Point speeds of individual vehicle at freeway diverge area, upper ramp, and lower ramp are collected by radar guns. Safety performance of 37 exit ramps are appraised using three different measures, namely, ΔV₈₅, 85(ΔV), and 85(ΔV)R. The results show that 85(ΔV) is 1.42 to 2.02 times of ΔV₈₅, and that the evaluation result of 85(ΔV)R is between the other two. The measure 85(ΔV)R considers not only individual speed but also the base speed on upstream element, which avoid the pitfalls of ecological fallacy and overestimation possessed by conventional measures. It is a safer and reasonable measure that should be adopted in practice.     

Measurement of swarm parameters of c-C4F8/CO2 and its insulation characteristics analysis

In c-C₄F₈ and c-C₄F₈/CO₂ mixtures, the swarm parameters including ionization coefficient, attachment coefficient and effective ionization coefficient were obtained at the ratio of the electric field strength to the gas density between 150–550 Td by the steady-state Townsend (SST) method. Static breakdown voltages at each ratio were also measured at the SST condition. The limiting field strengths were obtained by two methods: computing the density-normalized effective ionization coefficient as a function of the overall density-reduced electric field strength; and measuring static breakdown voltages as a function of the product of gas density and electrode separation. Good agreement was obtained by these two methods, which ensures the correctness of the former method. The limiting field strengths of c-C₄F₈ and c-C₄F₈/CO₂ mixtures were compared with those of pure SF₆, SF₆/CO₂ mixtures and pure c-C₄F₈. It is found that buffer gas CO₂ does not reduce the limiting field strengths of c-C₄F₈ greatly, the limiting field strengths of c-C₄F₈/CO₂ mixtures are higher than those of SF₆/CO₂ mixtures or even pure SF₆, and so c-C₄F₈/CO₂ mixtures are suggested to be possible substitutes for SF₆. Foundation item: the National Natural Science Foundation of China (No. 50777041)     

Numerical simulation of thermal and iron ore reduction conditions in pre-reduction shaft furnace based on reducing gas composition and temperature

Based on the principles of mass, momentum and heat transfers between the reducing gas and the iron ore solid, a two-dimensional mathematical model for above two phases is established to study the influences of reducing gas composition on thermal and reduction conditions in pre-reduction shaft furnace with the temperature ranging from 1 023 to 1 223K. Due to the strong endothermic effect of iron ore reduction participated by hydrogen (H₂), increasing the ratio of carbon monoxide (CO) to H₂ enlarges high temperature zone under present calculation conditions, thus improves reduction efficiency inside the furnace. In addition, replacing of the reducing gas with an appropriate proportion of nitrogen (N₂) featuring the same temperature has a potential to reduce fuel consumption by as much as 6.5% while the products of similar quality are yielded.     

NFκBIA HaeⅢ、EC-SOD基因多态性和饮酒与溃疡性结肠炎的相关性

目的探讨核转录因子-κB抑制因子HaeⅢ(NFκBIA HaeⅢ)、细胞外超氧化物岐化酶(EC-SOD)基因多态性和饮酒与溃疡性结肠炎(UC)发病之间的关系。方法采用病例-对照研究的方法,以400例UC患者及400例健康对照者的外周血白细胞为样本,利用聚合酶链反应(polymerase chain reaction,PCR)技术分析了NFκBIA HaeⅢ和EC-SOD基因多态性。结果 NFκBIA HaeⅢ(Non-A/A)基因型和EC-SOD(C/G)基因型频率分布分别为39.50%、71.50%(病例组)和21.25%、43.00%(对照组),二者经χ2检验差异有统计学意义(P<0.01;P<0.01)。NFκBIAHaeⅢ(Non-A/A)患UC的风险显著增加(OR=2.419 5,95%CI=1.827 1～4.065 4)。EC-SOD(C/G)基因型者患UC的风险也显著增加(OR=3.325 6,95%CI=1.908 5～4.538 7)。基因突变的协同分析发现,NFκBIA HaeⅢ(Non-A/A)/EC-SOD(C/G)基因型者在UC组和对照组中的分布频率分别为32.50%和6.25%,二者经χ2检验有显著性差异(P<0.01)。NFκBIA HaeⅢ(Non-A/A)/EC-SOD(C/G)基因型者患UC的风险显著增加(OR=10.158 1,95%CI=4.192 4～12.309 4)。病例组的饮酒率显著高于对照组(OR=2.583 7,95%CI=1.408 1～4.932 6,P<0.01),NFκBIA HaeⅢ(Non-A/A)/EC-SOD(C/G)基因型与饮酒有协同作用(OR=35.209 9,95%CI=19.975 1～62.592 2)。结论 NFκBIA HaeⅢ(Non-A/A)/EC-SOD(C/G)基因型和饮酒是UC的易患因素,三者在UC发生中起协同作用。     

Monte Carlo simulation of B2-L2<Subscript>1</Subscript> ordering transitions in Au-Cu-Al alloy systems

The B2-L2₁ ordering transitions in Au-Cu-Al shape-memory alloys are studied by the Monte Carlo exchange simulations, where a set of the first, the second and the third nearest-neighbor mixing potentials for Cu-Al in the Au-Cu-Al alloys are calculated from first principals using the Connolly-Williams methods. To ensure the phase stability of the β-Au-Cu-Al, the investigation includes the range of compositions Au₂Cu_1−x Al_1+x (−0.15 ⩽ x ⩽ 0.15). The B2-L2₁ transition temperatures are predicted, and are in agreement with the experimental results. The atomic ordering around vacancy of the L2₁ structure is further discussed.     

Impacts of CaO Solid Particles in Carbon Dioxide Absorption Process from Ship Emission with NaOH Solution

CO₂ emitted from ship exhaust is one of the major sources of atmospheric pollution. In order to reduce ship CO₂ emissions, this paper comes up with the idea of recovering CO₂ from ship exhaust by NaOH solution and improves the absorption rate by adding CaO solid particles. The effect mechanism of CaO solid particles on CO₂ absorption efficiency is analyzed in detail, and the mathematical model is deduced and the CaO enhancement factor is calculated through experiments. Experiment result demonstrates that the effect of CaO solid particles on the absorption of CO₂ in alkali solution is significant. The absorption rate of pure CO₂ gas, the simulated ship exhaust gas and 6135AZG marine diesel engine emission can be increased by 10%, 15.85% and 10.30%, respectively. So it can be seen that CaO solid particles play an important role in improving the absorption efficiency of ship CO₂ emission.     

Modified Nafion polymer electrolyte membranes by ��-ray irradiation used in direct methanol fuel cells

Modification of the commercial polymer electrolyte membrane (PEM) Nafion 117 by ??-ray irradiation to produce an improved proton exchange membrane for direct methanol fuel cells (DMFCs) was described. The Nafion 117 membrane was exposed under ??-ray irradiation circumstance with the irradiation doses from 10³ to 10⁵ Gy. Subsequently the properties of the membrane itself, in terms of swelling ratio, water uptake rate, proton conductivity and methanol permeability, together with the performance of its membrane electrode assembly (MEA) in DMFC were analyzed and contrasted with the untreated material. When the Nafion 117 membrane was exposed under ??-ray irradiation circumstance, the degradation and crosslinking reactions occurred at the same time. Specific scopes of the ??-ray irradiation dose may cause the membrane crosslinking, thus reduce the membrane swelling ratio and decrease the methanol crossover. By reducing the membrane swelling ratio and methanol permeation, the single DMFC with the modified Nafion 117 membrane produced reasonable power density performance as high as 32W/m² under 2mol/L methanol solution at room temperature.     

Improvement the electrochemical performance of Li1.2Ni0.2Mn0.6O2 electrode with AlF3 added

Layered solid solution material Li_1.2Ni_0.2Mn_0.6O₂ is synthesized and the AlF₃ is added to improve the electrochemical performance. X-ray diffraction (XRD) results show that the Li_1.2Ni_0.2Mn_0.6O₂ samples exhibit layered characteristics. The AlF₃ additive is detected by transmission electron microscope (TEM) technology. The electrochemical tests show that Li_1.2Ni_0.2Mn_0.6O₂ electrode with AlF₃ added delivers better discharge capacity (240mA· h/g), first coulomb efficiency 79.2%, cyclic performance (capacity retention ratio of 100.6% after 50 cycles), and rate capacity (68mA · h/g at 10 capacity (C)) than the pristine sample. Electrochemical impedance spectroscopy (EIS) results show that the charge transfer resistance of Li_1.2Ni_0.2Mn_0.6O₂ electrode with AlF₃ added increases slower than that of pristine Li_1.2Ni_0.2Mn_0.6O₂ after cycling, which is responsible for better cyclic and rate performance.     

Hydrogen adsorption by woodceramics produced from biomass

Hydrogen adsorption characteristics of woodceramics, made from radiata pine wood fiber boards carbonized at 1 473K after impregnation with phenolic resin, with and without chemical treatment in an alkaline (KOH) or an acid (H₂SO₄) solution were investigated The hydrogen adsorption capacity is improved by chemical treatment. The chemical treatment by KOH improves the adsorption capacity more than by H₂SO₄. The improvement of the capacity level, in any solution, is dependent on the type of chemical in the solution and its concentration. The maximum hydrogen capacity measured at 93K is mass fraction about w(H) = 2% for the woodceramics after chemical treatment in a volume fraction ?? = 50% KOH solution, although that is about w(H) = 0.7% for one without chemical treatment. The microscopic condition of pores in the woodceramics is thought to vary after chemical treatment.