Estimation of growth rate in unidirectionally solidified multicrystalline silicon by the growth-induced striation method

Multicrystalline silicon was grown by unidirectional solidification method using the accelerated crucible rotation technique. The application of the accelerated crucible rotation technique in unidirectional solidification method induced growth striations across the axial direction of the grown crystal. This striation pattern was observed from carbon concentration distribution, obtained by using Fourier transform infrared spectroscopy. The generated striation pattern was found to be weak and discontinuous. Some striations were absent, probably due to back melting, caused during each crucible rotation. From the growth striations and applied time period in crucible rotation, the growth rate was estimated by using Fourier transformation analysis.     

DNA-conjugated polymers for self-assembled DNA chip fabrication.

We developed two DNA-conjugated polymers, one based on polyallylamine and the other on polyacrylic acid, for use in DNA chips. A 30-mer single-stranded DNA probe and thioctic acid were covalently attached to polyallylamine as sidechains. The same single-stranded DNA and 3-(pyridyldithio)propionyl hydrazide were covalently attached to polyacrylic acid as sidechains. Both DNA-conjugated polymers could be specifically immobilized onto a gold sensor substrate by a self-assembly technique. The interactions between fully matched DNA and each DNA-conjugated polymer were investigated by surface plasmon resonance. A gold surface modified with either DNA-conjugated polymer recognized fully matched DNA much better than unmatched DNA. The hybridization selectivity and efficiency of DNA-conjugated polyallylamine was optimized by adjusting the pH so as to reduce the effects of cationic polymer sidechains. The hybridization selectivity and efficiency of DNA-conjugated polymers were higher than those of a conventional immobilized thiol-based DNA. The coating of DNA-conjugated polymers reduced nonspecific adsorption of DNA by the gold substrate. DNA-conjugated polyacrylic acid was more selective toward fully matched DNA than was DNA-conjugated polyallylamine. Therefore, DNA-conjugated polymers show promise for application in novel DNA chips.     

Certain condition on the second fundamental form of CR submanifolds of maximal CR dimension of complex Euclidean space

We treat m-dimensional real submanifolds M of complex space forms ̿M when the maximal holomorphic tangent subspace is (m−1)-dimensional. On these manifolds there exists an almost contact structure F which is naturally induced from the ambient space and in this paper we study the condition h(FX,Y)−h(X,FY) = g(FX,Y)η, η∊ T⊥(M), on the structure F and on the second fundamental form h of these submanifolds. Especially when the ambient space ̿M is a complex Euclidean space, we obtain a complete classification of submanifolds M which satisfy these conditions.Mathematics Subject Classifications (2000): 53C15, 53C40, 53B20.     

Self-assembled DNA-conjugated polymer for novel DNA chip.

We developed DNA-conjugated polymer for DNA chip fabrication. A 30 mer probe DNA and disulfide bridges were covalently attached to the polymer side chain. The DNA-conjugated polymer can be specifically adsorbed on a gold substrate surface by a self-assembly technique. The interaction between fully matched DNA and DNA-conjugated polymer was investigated by surface plasmon resonance (SPR) technique. The DNA-conjugated polymer-modified gold surface highly recognized fully matched DNA, rather than unmatched DNA. Therefore, DNA-conjugated polymer can be used for novel DNA chip fabrication.     

Borderline of hydrogen bonding of silanols

Two new silanols bearing very bulky silyl groups, (i-Pr₃ Si)₃SiOH and (t − BuMe₂Si)₃SiOH were prepared by peracidoxidation of their respective silanes. The X − ray crystallographic analysis revealed that (t − BuMe₂Si)₃ SiOH forms a dimeric structure with hydrogen bonding, while (i − Pr₃ Si)₃ SiOH exists as a monomer in the crystal. The effects of the size of the substituents as well as the reactivity of these silanols are discussed.     

Spectroscopic and Electrochemical Characterization of Cytochrome P450st‐DDAB Films on a Plastic‐Formed Carbon Electrode

We have studied the characterization of thermophilic cytochrome P450 (P450st)‐didodecyldimethylammonium bromide (DDAB) films by using UV‐vis absorption, resonance Raman spectroscopy, and electrochemical methods. The observed Raman spectrum indicated near‐native conformation of the heme iron in DDAB film on the surface of a glass slide, while on the surface of a plastic‐formed carbon (PFC) electrode, the conformation of P450st‐DDAB was very similar to that of heme‐DDAB film, suggesting the release of heme from P450st in DDAB films on PFC electrodes. When NaBr was added as salt to the casting solution, the result of Raman spectrum indicated near‐native conformation of P450st in DDAB film even on the PFC electrode, but no redox potential of P450st which has near native structure was observed. This study suggests the essential experimental conditions when working with heme protein‐DDAB films as, in some cases, heme iron from proteins is released on the surface of the electrode.     

Photochemical preparation of poly(N-vinyl-2-pyrrolidone)-stabilized platinum colloids and their deposition on titanium dioxide

Preparation processes for Pt-deposited TiO(2) (Pt/TiO(2)) by the synthesis of Pt nanoparticles and their deposition were pursued by transmission electron microscopy, extended X-ray absorption fine structure, UV-vis spectroscopy, and Fourier transform infrared spectroscopic studies. Colloidal dispersions of Pt particles stabilized by poly(N-vinyl-2-pyrrolidone) (PVP) were photochemically synthesized in aqueous ethanol solution. The average diameter of Pt particles was estimated to be 2.0 +/- 0.5 nm, which was almost unchanged by changing the reducing agent from ethanol to methanol and 2-propanol. The PVP-stabilized Pt particles were distributed over a TiO(2) surface only by mixing the Pt colloidal dispersions and TiO(2). CO was chemically coordinated on the Pt particles on a TiO(2) surface after heat treatment was carried out in an O(2) flow at 673 K to completely remove the residual PVP on Pt/TiO(2). Hydrogen reduction at 473 K did not increase the amount of CO adsorbed on Pt sites. The Pt/TiO(2) catalyst after the oxidation treatment showed higher activity for CO photooxidation than that obtained for pure TiO(2) catalyst. The CO photooxidation rate was not unchanged by the H(2) reduction.     

Single molecular multianalyte sensor: jewel pendant ligand

[structure: see text] The jewel pendant ligand has multiple chromogenic units combined in a single molecule with the dyes linked to a semiselective binding site by three heteroatoms (O, N, S) having different HSAB characteristics, to indicate diverse response to individual transition metal ions. Using a single-molecular multianalyte sensor, multiple analytes could be determined with a minimal sensing system.     

Synthetic study of optically active 3-azabicyclo[3.3.0]octane-2,6,8-tricarboxylic acid

Synthesis of (1R,2S,5S,6R,8S)-3-azabicyclo[3.3.0]octane-2,6,8-tricarboxylic acid (2) from trans-4-hydroxy-L-proline (5) was attempted. A Diels-Alder reaction of 3,4-dehydroproline derivative 9 and cyclopentadiene afforded a single stereoisomer 11. The Diels-Alder adduct was smoothly converted to the hydrochloride of 2 (24) via RuO(4) oxidation. Although some racemization of the material or product was observed during the synthetic processes, the amino acid 24 proved to be optically pure.     

Near-infrared fluorescent probes: a next-generation tool for protein-labeling applications

The development of near-infrared (NIR) fluorescent probes over the past few decades has changed the way that biomolecules are imaged, and thus represents one of the most rapidly progressing areas of research. Presently, NIR fluorescent probes are routinely used to visualize and understand intracellular activities. The ability to penetrate tissues deeply, reduced photodamage to living organisms, and a high signal-to-noise ratio characterize NIR fluorescent probes as efficient next-generation tools for elucidating various biological events. The coupling of self-labeling protein tags with synthetic fluorescent probes is one of the most promising research areas in chemical biology. Indeed, at present, protein-labeling techniques are not only used to monitor the dynamics and localization of proteins but also play a more diverse role in imaging applications. For instance, one of the dominant technologies employed in the visualization of protein activity and regulation is based on protein tags and their associated NIR fluorescent probes. In this mini-review, we will discuss the development of several NIR fluorescent probes used for various protein-tag systems.

This minireview describes the development of NIR chemical probes for various protein-tag systems.