Synthesis,structure, stability and phase diagrams of selected bimetallic silver- and nickel-based nanoparticles

An overview of the research on silver-based (Ag-Sn, Ag-Cu, Ag-Ni) and nickel-based (Cu-Ni, Au-Ni, Ni-Pt) bimetallic nanoparticles is presented. The investigated nanoparticles in this review are formed by elements that represent an important group of metals revealing fcc lattice under macro-sized conditions (with the exception of Sn). The effects of surface stabilizing layer of the alloy nanoparticles are also described. Our experience with synthesis, characterization and stabilization of alloy nanoparticles is summarized. The development of the nanoparticle synthesis represents an important and mandatory part of the experimental nanoalloy research. Main synthetic routes under focus are the low temperature borohydride reduction method, the high temperature oleylamine synthesis, and the high pressure method in autoclave. The subsequent structural studies are focused on both nanoparticle core and outer stabilizing layer. The cores of the nanoparticles are studied mainly by electron microscopy techniques. The phase stability of the nanoparticle core is investigated by thermal analysis. The Knudsen effusion mass spectrometry was applied for studies of stabilizing organic molecules that can be found on the surface of the nanoparticles. The presented overview of the experimental results is complemented by thermodynamic calculations of phase diagrams by the CALPHAD method.     

Onset of buoyancy-driven convection in melting from below

When a horizontal homogeneous solid is melted from below, convection can be induced in a thermally unstable melt layer. In this study the onset of buoyancy-driven convection during time-dependent melting is investigated by using similarly transformed disturbance equations. The critical Rayleigh numbers based on the melt-layer thickness are found numerically for various conditions. For small superheats, the present predictions approach the well known results of classical Rayleigh-Bénard problems, that is, critical Rayleigh numbers are located between 1,296 and 1,708, regardless of the Prandtl number. However, for high superheats the critical Rayleigh number increases with an increase in phase change rate but with decrease in Prandtl number.     

不饱和单体熔融接枝PP体系中引发剂的选择

本文选择了过氧化异丙苯、过氧化苯甲酰、二叔丁基过氧化物三种引发剂进行实验。比较了三种引发剂的基本性能。讨论了引发剂种类及用量对接枝反应的影响，并研究了三种引发剂对ＰＰ降解及对接枝物外观颜色的影响。     

废钢在电炉中的高效熔化技术的发展

随着电炉炼钢技术的发展，电炉已成为一种高效的废钢熔化设备，本文从利用初级燃料及电炉废气能的观点出发，对强化电炉冶炼的措施进行了讨论．     

高炉炉渣流动性的实验研究

以宝钢高炉渣中的四大组元(CaO,SiO2,Al2O3,MgO)为基础,实验研究MgO,Al2O3含量及碱度对炉渣的熔化性温度和流动性的影响.结果表明,炉渣中Al2O3含量控制在16%,配制适量的MgO(9%～10%),在1 500℃以上的高温区域,炉渣仍能保持正常的流动性,适合炉缸温度充沛的高炉使用;MgO含量由6%增加到10%时,较明显地降低了炉渣粘度,粘度的递减值约为0.07～0.15 Pa.s.     

Influence of residual milk-clotting enzyme and proteolysis on melting properties of soft cheese

In this work, we assessed the influence of coagulant residual activity and primary proteolysis on Cremoso Argentino cheese melting properties. For that purpose, we made Cremoso soft cheeses using different amounts of coagulant, and also obtained samples in which milk-clotting enzyme was inactivated. Primary proteolysis correlated with residual activity of coagulant in early stages of cheese ripening; however, it was similar in all cheeses after 30 days. The hydrolysis of caseins did not significantly affect the melting ability of the cheeses, expressed as the area increase after heating samples under standardized conditions. Samples with similar proximate composition showed some changes in meltability; those seemed related to pH evolution during ripening.     

Flame retardant and the degradation mechanism of high impact polystyrene/Fe-montmorillonite nanocomposites

High impact polystyrene/Fe-montmorillonite (HIPS/Fe-MMT) nanocomposites were successfully prepared by melting intercalation. The nanostructures of HIPS/Fe-MMT were testified by X-ray diffraction (XRD) and transmission electron microscope (TEM). Corresponding to pure HIPS, the thermal stability of HIPS/Fe-MMT nanocomposites was notably improved. The peaks of heat release rate (PHRR) and the mass loss rate (MLR) were significantly reduced after the formation of the HIPS/Fe-MMT nanocomposites from cone calorimetry. And nanocomposites PHRR was further lower with the increase of Fe-MMT content in the range of 1 to 5 wt%. The degradation mechanism of HIPS and HIPS/Fe-MMT nanocomposites was conducted by pyrolysis gas chromatography mass spectrometry (Py-GC-MS). And the reason of the enhancement of thermal stability maybe is that structural iron is the operative site for radical trapping in the Fe-MMT and the nanostructure enhances the interaction of the chains of the HIPS.     

Composite group vector space method for estimating melting and boiling point of pure organic compound

Composition Group Vector Space (CGVS) method for estimating melting and boiling point T _m , T _b of organic compound has been proposed, and the principle of this method has been elucidated. The models for estimating T _m , T _b have been established and the numerical values of relative parameters have been presented. The average percentage deviations of T _m , T _b estimation are 7.53 and 1.58, respectively, which show that the present method demonstrates significant improvement in applicability to predict the above properties, compared to conventional group methods.     

Electroless plating of copper on polyimide films modified by surface grafting of tertiary and quaternary amines polymers

Argon plasma-pretreated polyimide (PI, Kapton^® HN) films were subjected to UV-induced surface graft copolymerization with N,N′-(dimethylamino)ethyl methacrylate (DMAEMA) and 2-(trimethylammonium)ethyl methacrylate chloride (TMMAC). The DMAEMA graft-copolymerized PI (DMAEMA-g-PI) surfaces were also quaternized and amino-functionalized with 3-bromopropylamine hydrobromide (the Q-DMAEMA-g-PI surfaces). The surface composition and the degree of quaternization of the graft-modified PI films were determined by X-ray photoelectron spectroscopy. The DMAEMA-g-PI, Q-DMAEMA-g-PI and TMMAC graft-copolymerized PI (TMMAC-g-PI) surfaces can be activated directly by PdCl₂, in the absence of prior sensitization by SnCl₂ (the ‘Sn-free’ activation process), for the subsequent electroless plating of copper. A shorter induction time for the electroless deposition of copper was found for the palladium-activated Q-DMAEMA-g-PI and TMMAC-g-PI surfaces than for the palladium-activated DMAEMA-g-PI surface. The T-peel adhesion strength of the electrolessly deposited copper with the Q-DMAEMA-g-PI surface was enhanced to above 6 N/cm, in comparison to only about 4 N/cm for the DMAEMA-g-PI surface, about 2.5 N/cm for the TMMAC-g-PI surface, or about 0.5 N/cm for the PI surface with argon plasma treatment alone.