Fabrication and structural characterization of TiO nanoparticle soft-landed on substrate by the magnetron sputtering-gas aggregation method

We have succeeded to fabricate the thin film mainly or entirely consisting of nano-crystallites TiO on a substrate at room temperature by using the magnetron sputtering combined with the gas aggregation method which has the capability to deposit grown small particles and/or clusters of the desired compound material on the substrate in soft-landed mode. The important experimental parameters to control the growth of TiO particles are identified as partial pressure of additional oxygen gas, growth-reaction distance L_td, and LN₂ cooling of growth chamber. The smallest averaged diameter of TiO nano-particles is 5.62 nm and size distribution being from 2 to 8 nm under 50 mm of L_td. The compositional uniformity is confirmed by EDS and EELS. The chemical state of the film observed by Ti 2P XPS peak confirms the primarily growth of TiO and indicates the formation of minor content of amorphous Ti_1-xO_x and/or Ti_1-xC_x particularly at the surface of the film.     

Studies on Polymerization Activities by Soluble Catalysts Based on Compounds of Organotransition Metals and Aluminum Alkyls

Polymerization activities of the soluble Ziegler-type of catalyst systems, Ti(OR)₄-AlEt₃, Ti(NEt₂)₄-AlMe₃, and V(NEt₂)4-AlEt₃, were investigated. In the catalyst system of Ti(OR)₄-AlEt₃, formation of two types of Ti(III) compounds, i.e., Ti(OR)₂Et and its bridged complex with aluminum alkyl, was confirmed by IR and ESR measurements. With the addition of donor molecule to the system, it was found that the polymer yield decreased remarkably and that the bridged complex dissociated into a single or uncomplex Ti(III) paramagnetic species. It has been concluded that the bridged structure of Ti(III) species was responsible for the polymerization activity of styrene. Two reaction products of Ti(NEt₂)₃Me and Al(NEt2)Me₂ were found by NMR spectroscopic observation with the Ti(NEt₂)₄-AlMe₃ catalyst system. From the kinetic study of polymerization of styrene, it was found that Ti(NEt₂)₃Me is an active species. An anionic mechanism was proposed for the styrene polymerization by Ti(NEt₂)₃Me. In the polymerization of MMA with the V(NEt₂)₄-AlEt₃ system, a difference in the tacticity of polymer was found to depend on the polymerization conditions, e.g., AI/V ratio and temperature. From an analysis of the tacticity of the polymer, the presence of two active sites in the propagation process is suggested.     

Atomic absorption spectrometric determination of trace copper in water by sorption on an ion-exchange resin and direct atomization of the resin

Traces of copper ions are sorbed on a cation-exchange resin, and a copper-loaded resin bead is inserted directly into a graphite furnace for atomic absorption spectrometry. The procedure is used for the determination of copper ( > 2 pg ml^?1) in tap and various distilled waters.     

Carbon-Based Materials: Growth,Properties, MEMS/NEMS Technologies,and MEM/NEM Switches

Micro- or nanoelectromechanical system (MEMS/NEMS) is a multidisciplinary field, which has witnessed explosive growth during the past decades. The current materials for MEMS are dominated by Si thanks to the fully based technology for CMOS. However, Si has its own intrinsic limitations such as poor mechanical or tribological properties and poor thermal stability. Carbon-based materials such as diamond, carbon nanotube, and graphene possess excellent properties such as low mass, high Young's modulus, high thermal conductivity, hydrophobic surface, and tailorable electronic configuration, which make these materials promising for MEMS/NEMS applications with diverse and much better performance than Si. In this review, we describe the recent progress of carbon-based materials for MEMS/NEMS with focus on diamond, carbon nanotube, and graphene. The growth of these carbon materials is briefly described and only selected properties are discussed with respect to MEMS/NEMS applications. The fabrication process for suspended structures of these materials toward MEMS/NEMS is comprehensively reviewed from the recent literatures. Special attention is devoted to the state-of-the-art of MEM/NEM switches based on these carbon materials, one of the most important fields in MEMS/NEMS. Finally, the application of carbon-based MEM/NEM switches to microwave field is critically analyzed.     

MOVPE growth and properties of GaN on (1 1 1)Si using an AlInN intermediate layer

Using an AlInN intermediate layer, GaN was grown on (1 1 1)Si substrate by selective metalorganic vapor phase epitaxy. The variation of the surface morphology was investigated as a function of the In composition and thickness of the AlInN layer. It was found that the In composition in the AlInN layer was a function of the growth temperature and thickness. Because of the small band offset at the AlInN/Si hetero-interface, we have achieved a low series resistance of the order of 9 Ω (0.0036 Ω cm²) across the GaN/AlInN/AlN/Si layer structure.     

Effect of binding and conformation on fluorescence quenching in new 2',7'-dichlorofluorescein derivatives

[structure: see text] Symmetrical and unsymmetrical 2',7'-dichlorofluorescein (DCF) derivatives have been synthesized by means of Mannich reactions and an aromatic Claisen rearrangement. NMR and fluorescence spectroscopic studies reveal the correlation between the conformations, the photoinduced electron transfer mechanism, and fluorescent intensities of these DCF derivatives. Two quenching nitrogen atoms cooperatively and reversibly suppress the fluorescence of the chromophore.     

A Stable Organic π‐Radical of a Zinc(II)–Copper(I)–Zinc(II) Complex of Decaphyrin

A Zn^II‐Cu^I‐Zn^II heterotrimetal complex of decaphyrin was synthesized by stepwise metalations: metalation of a [46]decaphyrin with Zn^II ions to produce a 46π decaphyrin bis(Zn^II) complex and its subsequent metalation with Cu^II ion. In the second metalation step, it has been shown that Cu^II ion is reduced to a Cu^I ion in the complex and a dianionic bis(Zn^II) containing [46]decaphyrin ligand is oxidized to the corresponding monoanionic [45]decaphyrin ligand, indicating a non‐innocent nature of the decaphyrin ligand. Despite the radical nature, the heterotrimetal complex is fairly stable under ambient conditions and exhibits almost no intermolecular magnetic interaction, owing to extensive delocalization of an unpaired electron in the large π‐conjugated circuit of decaphyrin moiety.     

Fluorescent sensors for specific RNA: a general paradigm using chemistry and combinatorial biology

Here, we describe a new paradigm for the development of small molecule-based RNA sensors. We prepared a series of potential PET (photoinduced electron transfer) sensors on the basis of 2',7'-dichlorofluorescein (DCF) fluorophore conjugated with two aniline derivatives as electron donors (quenchers). NMR and fluorescent spectroscopic analyses of these DCF derivatives revealed the correlation between the conformations, the PET, and the fluorescent intensities of these DCF derivatives, enabling us to select a sensor candidate. RNA aptamers were raised against the aniline-based quencher via in vitro selection (SELEX). One of these aptamers enhanced the fluorescence intensity of the DCF-aniline conjugate in a concentration-dependent manner. To demonstrate the power and generality of this approach, additional in vitro selection was performed and aptamers from this selection were found to have similar activities. These results show that one can develop fluorescence-inducing reporter RNA and morph it into remotely related sequences without prior structural insight into RNA-ligand binding.