Studies of tetracene- and pentacene-based organic thin-film transistors fabricated by the neutral cluster beam deposition method

The neutral cluster beam deposition (NCBD) method has been applied to produce and characterize organic thin-film transistors (OTFTs) based upon tetracene and pentacene molecules as active layers. Organic thin films were prepared by the NCBD method on hexamethyldisilazane (HMDS)-untreated and -pretreated silicon dioxide (SiO2) substrates at room temperature. The surface morphology and structures for the tetracene and pentacene thin films were examined by atomic force microscopy (AFM) and X-ray diffraction (XRD). The measurements demonstrate that the weakly bound and highly directional neutral cluster beams are efficient in producing high-quality single-crystalline thin films with uniform, smooth surfaces and that SiO2 surface treatment with HMDS enhances the crystallinity of the pentacene thin-film phase. Tetracene- and pentacene-based OTFTs with the top-contact structure showed typical source-drain current modulation behavior with different gate voltages. Device parameters such as hole carrier mobility, current on/off ratio, threshold voltage, and subthreshold slope have been derived from the current-voltage characteristics together with the effects of surface treatment with HMDS. In particular, the high field-effect room-temperature mobilities for the HMDS-untreated OTFTs are found to be comparable to the most widely reported values for the respective untreated tetracene and pentacene thin-film transistors. The device performance strongly correlates with the surface morphology, and the structural properties of the organic thin films are discussed.     

Bioconversion of cellulose into ethanol by nonisothermal simultaneous saccharification and fermentation

The kinetic characteristics of cellulase and beta-glucosidase during hydrolysis were determined. The kinetic parameters were found to reproduce experimental data satisfactorily and could be used in a simultaneous saccharification and fermentation (SSF) system by coupling with a fermentation model. The effects of temperature on yeast growth and ethanol production were investigated in batch cultures. In the range of 35-45 degrees C, using a mathematical model and a computer simulation package, the kinetic parameters at each temperature were estimated. The appropriate forms of the model equation for the SSF considering the effects of temperature were developed, and the temperature profile for maximizing the ethanol production was also obtained. Briefly, the optimum temperature profile began at a low temperature of 35 degrees C, which allows the propagation of cells. Up to 10 h, the operating temperature increased rapidly to 39 degrees C, and then decreased slowly to 36 degrees C. In this nonisothermal SSF system with the above temperature profile, a maximum ethanol production of 14.87 g/L was obtained.     

Supramolecular conducting microfibers from amphiphilic tetrathiafulvalene-based organogelator

An amphiphilic tetrathiafulvalene molecule can gelate a variety of organic solvents in view of multiple intermolecular interactions, especially in polar solvent with the formation of highly-ordered columnar structures. The formation of mixed-valence states shows the semiconductive behaviors with the conductivity of 10^-4 S/cm, as promising candidates for organic electronics.     

Vacuum balance and related studies of green and red rusts

Green and red rusts are formed when iron is partially or completely oxidised. Analogues of the rusts may be precipitated from iron(II) and iron (III) salt solutions treated with alkali under reducing or oxidising conditions. Variations in surface area and porosity have been investigated by gravimetric nitrogen gas sorption, using vacuum microbalance techniques.Freshly-precipitated red rusts, hydrous iron (III) oxide, have surface areas of about 200–400 m²g^?1. When they are added to iron (II) hydroxide suspensions kept at pH 7, the green Fe (II)-Fe (III) rusts formed have lower surface areas of about 40–100 m²g^?1, depending on the initial iron(II) sulphate concentrations.     

Layered copper hydroxide n-alkylsulfonate salts: synthesis, characterization, and magnetic behaviors in relation to the basal spacing

A series of hybrid inorganic-organic copper(II) hydroxy n-alkylsulfonate with a triangular lattice, Cu(2)(OH)(3)(C(n)H(2)(n)(+1)SO(3)) (n = 6, 8, 10), are prepared by anion exchange, starting from copper hydroxy nitrate Cu(2)(OH)(3)NO(3). These compounds show a layered structure as determined by X-ray diffraction, with interlayer distances of 14.3-34.8 A in alternation with interdigitated bilayer packing. Magnetic properties have been investigated by means of dc and ac measurements. All the compounds show similar metamagnet behaviors, with a Neel temperature of about 11 K. A subtle difference in the ac magnetic susceptibility among the compounds is understood by the existence of hydrogen bonding between the sulfonate headgroup and the hydroxide anion. A detailed molecular structure of the alkyl chains incorporated to the inorganic copper hydroxide layer is also discussed from the FTIR data.     

硼酸溶液中氯柱硼镁石的溶解及相转化动力学

对氯柱硼镁石（2MgO•2B2O3•MgCl2•14H2O）在4.5％H3BO3水溶液40 ℃的溶解及相转化过程进行了动力学研究.对不同时间取出的液相的化学分析及不同阶段分离固相的鉴定结果表明,该复盐在溶解阶段出现与前所报导不同的同步溶解，最终产物是库水硼镁石（2MgO•3B2O3•15H2O）.提出了库水硼镁石的形成条件和溶解及相转化动力学机理，利用单纯形优化法配合Runge-Kutta微分方程组数值解法对实验数据进行处理，给出了转化结晶动力学方程.     

Chiral attachment of styrene mediated by surface dimers on Ge100

We have investigated the chiral adsorption configurations of styrene on Ge(100) using scanning tunneling microscopy at 300 K. The chemisorbed styrene on a single Ge dimer reduces the symmetry of the molecule, which produces a chiral center, and leads to the (S) or (R) chiral on-top configuration. We have found that the dimeric adsorption of styrene induced by the Ge surface dimer structure forms the enantiomeric and diastereomeric paired end-bridge configurations. We determine the absolute chirality of adsorbed styrene on Ge(100) and demonstrate a novel method for the achiral molecule to produce dimeric enantiomers and diastereomers attached to the semiconductor surface.