Showing papers in "Progress in Chemistry in 2012"

Hierarchical Equations of Motion for Quantum Dissipation and Quantum Transport

Abstract: In the mesoscopic world the nano-structured environment is not just of quantum in nature but also often nonperturbative and non-Markovian for its influence on the system of primary interest. In this talk, I will discuss the hierarchical equations of motion (HEOM) approach [1–4] that can be considered as a fundamental formalism in quantum mechanics of dissipative and open systems. HEOM is formally equivalent to such as the Feynman-Vernon influence functional and nonequilibrium many-body Green’s function formalisms [5], but numerically more implementable. It provides a unified treatment of various decoherence and quantum transport processes. It renders also a unified view on various existing approximated theories, such as the quantum master equation and stochastic Liouville equation [6], and consequently, often further results in some simple but important modifications to those conventional approximations [7]. I will also discuss about two recent developments, the best/minimum stochastic environment basis set for optimal HEOM construction [8] and the efficient on-the-fly numerical filtering algorithm [9], that significantly enhance the numerical tractability of the exact HEOM dynamics. Numerical results on the 2D spectrum of a model light harvesting antenna system and the quantum transport through Anderson model quantum dots system will be presented.

Vanadium-Based Catalysts for the Selective Catalytic Reduction of NOx with NH3

Abstract: Selective catalytic reduction of NOx with NH3 or urea (NH3/Urea-SCR) as reducing agents over catalytic materials in oxygen-rich conditions is one of the most efficient and widely-used techniques for the removal of NOx from stationary and mobile sources. The most important catalyst system for NH3-SCR process is vanadium-based catalyst. In this review, the composition and NH3-SCR performance, the activity improvement of vanadium-based catalysts and the corresponding NH3-SCR reaction mechanisms are summarized. The possible developing orientations in the field of NH3-SCR technique are also prospected. The conventional V2O5-WO3 (WoO(3))/TiO2 catalyst and corresponding improved vanadium-based catalysts usually show excellent deNO(x) efficiency and SO2 durability in the medium temperature range. On these catalysts, the highly dispersed V5+ species and poly-vanadate species are confirmed to be the active phase for NH3-SCR reaction. Over vanadium-bsed catalysts prepared by different methods or with different compositions, a majority of researchers consider that the NH3-SCR reaction follows an Eley-Rideal (E-R) mechanism and some researchers prefer to a Langmuir-Hinshelwood (L-H) mechanism, which might be related to the vanadium loading amount and reaction temperature. During the subsequent work in further study, the researchers should combine multiple characterization methods aiming at different catalyst systems, and pay more attention to the influence of temperature on the reaction mechanism together with the effect of surface acid/basic property on the adsorption and activation of NH3/NOx. Accordingly, much more comprehensive and authentic reaction mechanism can be concluded. The systematic understanding of the research progress in vanadium-based catalysts is beneficial to the development of highly efficient, stable vanadium-based SCR catalytic converters at the present stage, and also important for the design and synthesis of novel,efficient, environmentally-friendly vanadium-free SCR catalysts with high resistance to poisoning.

Novel Polyimide Materials Produced by Electrospinning

Abstract: Due to one-dimentional nanostructures’ unique properties and their intriguing applications, there has being a great demanding on the technologies which are able to produce such structures. Among the applicable strategies, electrospinning seems to be the simplest approach to generate continues nanofibers with ultrathin and uniform diameters (Li & Xia, 2004). Electrospinning is a spin technology which involves the use of a high voltage, usually directcurrent, to trigger the formation of a liquid jet (Li & Xia, 2004; Greiner & Wendorff, 2007).

Research of QSPR/QSAR for Ionic Liquids

Abstract: Ionic liquids, which are considered as the sustainable "green product", are gaining increasing interest due to their physical and chemical characteristics. Although a lot of efforts have been focused on the investigation of their syntheses and applications, structure-property/activity relationships of ionic liquids are poorly known to us. The quantitative structure-property/activity relationships (QSPR/QSAR) research methods and steps are described systematically in this article. The latest researches of quantitative structure-property/activity relationships on the melting points of ionic liquids, the infinite dilution activity coefficients of organic compounds, surface tensions of ionic liquids, conductivities of ionic liquids, solubility of organic solutes in ionic liquids, viscosities of ionic liquids and biological toxicity and degradation of ionic liquids are reviewed. Both advantages and disadvantages of the QSPR/QSAR used in the ionic liquid property prediction are discussed, and the prospective of this research area is proposed.

Steam Explosion Technology Applied to High-Value Utilization of Herb Medicine Resources

Abstract: Utilization of herb medicine requires combination of modern and traditional methods to develop new medicines which are high quality, safe, stable and convenient. At the same time, herb medicine resource is an important biomass resources, can be used to replace petroleum, gas and coal resources for energy, materials and chemicals production. Application of modern technology to enhance the value of the herb medicine resources is an important development direction for herb medicine research. The roles of steam explosion technology for high-value utilization of herb medicine resources are gradually exhibiting; steam explosion treatment can break the barriers of herb medicine plant cell wall structure, as a result, it is conducive to separation and extraction of active ingredients from medicine plant; steam explosion is contributed to the deglycosylation of glycosides in the natural plants and improves the efficiency of extraction and separation of aglycone; steam explosion is used in herb medicine processing and detoxification with several advantages such as efficient, fast, avoiding the loss of active ingredients, etc; steam explosion process is conducive to effective separation and utilization of non-medicinal components such as cellulose and hemicellulose for the production of ethanol, butanol and other energy and chemical products. This paper reviews the research of steam explosion technology for the high-value utilization of herb medicine resources.