Adsorption of hydrogen and hydrocarbon molecules on SiC(001)

Adsorption of hydrogen and hydrocarbon molecules on semiconductor surfaces plays a key role in surface science and technology. Most studies have employed silicon (Si) as a substrate because of its paramount technological importance and scientific interest. However, other semiconductor substrates are gaining an increasing interest as well. Silicon carbide (SiC), which is a material with very special properties allowing developments of novel devices and applications, offers particularly fascinating new degrees of freedom for exceptional adsorption behaviour. For example, a very unusual hydrogen-induced metallization of a SiC(001) surface has been reported and hydrogen molecules show very different adsorption behaviour on different SiC(001) reconstructions although the latter exhibit very similar surface dimers. In marked contrast to the Si(001) surface, the adsorption of hydrocarbon molecules on SiC(001) can yield structurally well-defined adlayers in favourable cases which may have large potential for organic functionalization. We review and discuss theoretical ab initio results on conceivable adsorption scenarios of atomic and molecular hydrogen as well as acetylene, ethylene, butadiene, benzene and cyclohexadiene on various reconstructions of the SiC(001) surface. The main emphasize is on a detailed understanding of these adsorption systems and on identifying the physical origin of the particular adsorption behaviour. The results will be discussed in the light of related adsorption events on the Si(001) surface and in comparison with available experimental data.     

Trace analysis of anions in organic matrices by ion chromatography coupled with a novel reversed-phase column for on-line sample pretreatment

An ion chromatography(IC) system coupled with on-line column-switching technique was used to determine anions ofμg/g levels in organic chemicals of analytical reagent grade.A novel polystyrene-divinylbenzene-carbon nanotube(PS-DVB-CNT) stationary phase was utilized for matrix elimination.A calibration study was conducted by preparing and analyzing eight concentrations(between 10 and 5000μg/L) of eight standards in deionized water.The linearity was between 0.9978 and 1.And the detection limits ranged from 1.54μg/L to 10.02μg/L.A spiking study was performed on two representative organic chemicals.The recoveries were between 84.3%and 119.6%.     

Molecule and ion recognition of nano-baskets of calixarenes since 2005

Two new isomorphous oxovanadium composite solids, [Zn(btx)V₂O₆] (1) and [Cu(btx)V₂O₆] (2) (btx = 1,4-bis(triazol-1-ylmethyl)benzene), have been synthesized and characterized by elemental analysis, IR, TGA, and single-crystal X-ray diffraction. The structures of 1 and 2 are composed of {MV₂O₆} (M = Zn or Cu) bimetallic oxide layers, linked through {MO₂N₂} building blocks and btx ligands into 3-D architectures. The two compounds consist of infinite spiral chains and all helical chains are meso-helices, which lead to racemic solid-state compounds. The electrochemical properties of the two compounds have been studied.     

Electrochemistry of Klason Lignin

The possibility of the use of Klason lignin extracted from sunflower husks as a cathode-active material for primary lithium battery has been demonstrated for the first time. The chemical composition, morphological and physical features were characterized by X-ray energy dispersive spectroscopy, impedance spectroscopy, scanning electron microscopy, and infrared spectroscopy. Electrochemical behavior of Klason lignin vs. Li/Li⁺ was studied by galvanostatic discharge and cyclic voltammetry. The reaction mechanism in electrochemical system was discussed. The maximum specific capacity of Klason lignin amounted to 380 mAh g^–1 at a current density of 25 mA g^–1.     

Chiral Morphology of Calcium Carbonate Mineralized in Agarose Gel

Calcareous crystallites with chiral morphology are difficult to obtain in vitro . Using the d ‐form of aspartic acid as crystal modifier, calcium carbonate with chiral morphology has been obtained in agarose gel. We show that the formation of the chiral morphology of crystallites does not necessarily involve complicated cellular processes.     

Organic light-emitting diode performance enhancement via indium tin oxide glass surface modification

A self-assembly monolayer (SAM), with phenyl-triethoxysilane (PTES), was used to modify the indium tin oxide anode for an organic light-emitting diode (OLED) in order to improve the OLED performance. The enhancement of OLED performance is attributed to the blockage of excessive hole injection by PTES, balancing the hole and electron injection numbers. The result indicates that the SAM process reaction time duration greatly affects the OLED performance outcomes. If the reaction time is too long, it will impact on the optical efficiency due to molecular aggregates accumulated on the SAM layers, thus reducing the performance of the OLEDs. The electrical and optical characteristics of the OLEDs are modeled by using the modified Shockley equation. Modified Shockley parameters are extracted to interpret the experimental data with excellent accuracy. Those parameters, both electrical and optical, can be used as the DC level modeling parameters for OLED product design simulations.     

Characterization of Fluorescence Induced by Side Illumination of Rhodamine B Doped Plastic Optical Fibers

The impact of a post-OTDM-demultiplexing optical filter on the performance of dense on-off keying (OOK) optical time division multiplexing (OTDM)—wavelength division multiplexing (WDM) systems was studied. For return-to-zero (RZ) modulation, it was found that the additional filter working in a double-tier filter configuration did not offer any significant improvements to performance when the signal pulse width is optimized. Improvements generally increase only when the signal pulse width deviates from its optimal value and only for low spectral densities. For ideal non-return-to-zero (NRZ) modulation, however, significant improvements of around 1 dB are obtained using the double-tier configuration over a large range of spectral densities.