Se-directed synthesis of polymeric carbon nitride with potential applications in heavy metal-containing industrial sewage treatment

By calcining melamine at 500 °C with selenium powder as the structure director, polymeric carbon nitride could be prepared with enhanced specific surface area and mesoporous volume. Compared with the material fabricated without Se, this cost-effective Se-incorporated PCN (PCN-Se) could adsorb heavy metals (such as Ni, Cu and Pb) much more efficiently. Materials characterizations such as SEM, TEM and XPS demonstrated that the enlarged specific surface area and total mesoporous volume as well as the interaction of the incorporated Se with the metals via coordination should be the promoting factors for the advanced performances of the novel materials.     

Welding dynamics in an atomistic model of an amorphous polymer blend with polymer–polymer interface

We consider an atomistic model of thermal welding at the polymer-polymer interface of a polyetherimide/polycarbonate blend, motivated by applications to 3D manufacturing in space. We follow diffusion of semiflexible chains at the interface and analyze strengthening of the samples as a function of the welding time t_w by simulating the strain–stress and shear viscosity curves. The time scales for initial wetting, and for fast and slow diffusion, are revealed. It is shown that each component of the polymer blend has its own characteristic time of slow diffusion at the interface. Analysis of strain–stress demonstrates saturation of the Young's modulus at t_w = 240 ns, while the tensile strength continues to increase. The shear viscosity is found to have a very weak dependence on the welding time for t_w > 60 ns. It is shown that both strain–stress and shear viscosity curves agree with experimental data.     

Emerging Electron Microscopy Techniques for Probing Functional Interfaces in Energy Materials

Interfaces play a fundamental role in many areas of chemistry. However, their localized nature requires characterization techniques with high spatial resolution in order to fully understand their structure and properties. State‐of‐the‐art atomic resolution or in situ scanning transmission electron microscopy and electron energy‐loss spectroscopy are indispensable tools for characterizing the local structure and chemistry of materials with single‐atom resolution, but they are not able to measure many properties that dictate function, such as vibrational modes or charge transfer, and are limited to room‐temperature samples containing no liquids. Here, we outline emerging electron microscopy techniques that are allowing these limitations to be overcome and highlight several recent studies that were enabled by these techniques. We then provide a vision for how these techniques can be paired with each other and with in situ methods to deliver new insights into the static and dynamic behavior of functional interfaces.     

Designing Covalent Organic Frameworks with a Tailored Ionic Interface for Ion Transport across One‐Dimensional Channels

A strategy based on covalent organic frameworks for ultrafast ion transport involves designing an ionic interface to mediate ion motion. Electrolyte chains were integrated onto the walls of one‐dimensional channels to construct ionic frameworks via pore surface engineering, so that the ionic interface can be systematically tuned at the desired composition and density. This strategy enables a quantitative correlation between interface and ion transport and unveils a full picture of managing ionic interface to achieve high‐rate ion transport. Moreover, the effect of interfaces was scaled on ion transport; ion mobility is increased in an exponential mode with the ionic interface. This strategy not only sets a benchmark system but also offers a general guidance for designing ionic interface that is key to systems for energy conversion and storage.     

QM/MM method for metal–organic interfaces

We present a QM/MM method for modeling metal/organic interfaces, which incorporates contributions from long‐range electron correlation, characteristic to metals and non‐bonded interactions in organic systems. This method can be used to study structurally irregular systems. We apply the method to model finite size domains of self‐assembled monolayers on the gold (111) surface and discuss the influence of boundary effects on the electrostatic and electronic properties of these systems. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010     

Effect of impurity atoms on α2/γ lamellar interfacial misfit in Ti–Al alloy: a systematic first principles study

The effect of transition metal solutes on the lattice parameters of γ-TiAl and α₂-Ti₃Al were studied by first principles calculations to find suitable elements for controlling the α₂/γ interfacial misfit in lamellar Ti–Al alloys. Better agreement was found between the calculated and experimental phase and site preferences of impurity atoms than in a previous first principles study. The calculated lattice parameters suggest that elements in groups 6–11 of the 4th period (Cr, Mn, Fe, Co, Ni and Cu) are effective for increasing the misfit, leading to increasing density of misfit dislocation and, in turn, higher yield strength and ductility. This effect is caused by the change in the lattice parameter of the γ-TiAl phase rather than those of α₂-Ti₃Al phase. This prediction agrees qualitatively with experimental data from a previous study although the effects of temperature are not taken into account. Further improvements should be possible by considering those effects. Nevertheless, the results highlight the effects of impurity addition on interfacial misfit at a level which cannot be achieved by classical concepts such as atomic size in a hard sphere model. The results will also be valuable in further more quantitative predictions and in understanding the effects of temperature, including off-stoichiometry, thermal expansion and vibration entropy.     

Phase Diagrams of a Transverse Ising Model with Interfaces

A transverse Ising model for a magnetic superlattice of spin-1/2 Ising layered media intercalated by periodic interfaces described by the spin-1/2 Ising model is considered. Phase diagrams and different profiles of magnetization determined by the parameters of the model are discussed within a variational procedure based on Bogoliubov's inequality for the free energy. Our results agree to those of the other's work at the limit of Ω = 0.     

弱光非晶硅太阳电池的研制

讨论了弱光下影响非晶硅太阳电池性能的主要因素,指出要提高弱光下太阳电池开路电压主要应提高太阳电池的并联电阻.用辉光放电法顺序沉积p, i, n三层非晶硅,制作出了弱光非晶硅太阳电池,在200lx白荧光灯照射下,其单位面积最大输出功率达7.76μW/cm2.     

Ethylene-Octene Copolymer-Nanosilica Nanocomposites: Effects of Epoxy Resin Functionalized Nanosilica on Morphology,Mechanical, Dynamic Mechanical and Thermal Properties

A comparative study of the structural, thermal, mechanical and thermomechanical properties of ethylene-octene copolymer 1

1 Ethylene-octene copolymer is produced using Dow's INSITETM ™ constrained geometry catalyst and process technology. ENGAGE the trade name of this copolymer.

(mPE) 2

2 This copolymer will be represented as mPE .

nanocomposites synthesized with pure nanosilica (NS) and nanosilica-functionalized with diglycidyl ether of bisphenol-A (ENS) has been reported. These nanocomposites were prepared using “melt mixing” method at a constant loading level of 2.5 wt. %. The effects of pure nanosilica (NS) and epoxy resin-functionalized-nanosilica (ENS) on the above mentioned properties of ethylene-octene copolymer were analyzed by wide-angle-x-ray diffractometer (WAXD), transmission electron microscope (TEM), thermo gravimetric analyzer (TGA), differential scanning calorimeter (DSC), dynamic mechanical analyzer (DMA) and scanning electron microscope (SEM). TEM studies have shown a better dispersion of nanoparticles in case of ethylene-octene copolymer-epoxy resin-functionalized-nanosilica nanocomposite (mPE-ENS) than that of ethylene-octene copolymer-nanosilica nanocomposite (mPE-NS). The tensile tests show that organic modification of nanosilica particles brings up an appreciable increase in yield strength, ultimate tensile strength and elongation at break of the polymer. DMA studies have shown an increase in the storage modulus and glass transition temperature for mPE-ENS with respect to mPE-NS. Further, the TGA results have shown a higher thermal stability for mPE-ENS in comparison to mPE-NS.