Study of the mechanism for controlled crystallization of BaF2 under two kinds of monolayers

Controlled crystallization of BaF2 under two different kinds of monolayers, octadecylamine [CH3(CH2)(17)NH2] and hexadecanol [CH3(CH2)(14)CH2OH], has been studied by using x-ray diffraction (XRD) and scanning electron microscope. It was found that the monolayer headgroup, the degree of ionization of the headgroup, etc., had a complicated effect on the selectivity of monolayers for crystal and on the morphology and orientation of crystals grown under the compressed monolayers. At pH = 7.0, XRD analysis showed that (100)-oriented BaF2 crystals were formed under the octadecylamine monolayer, while several kinds of crystals were found under the hexadecanol monolayer. In comparison, at pH = 8.5, both (100)-oriented BaF2 and (111)-oriented Ba(NO3)(2) crystals were obtained under the monolayer of octadecylamine. However, crystals formed under hexadecanol monolayer consist of BaF2, Ba(NO3)(2), etc. The detailed mechanism for crystallization was discussed in terms of the specific interaction and lattice matching between the monolayer headgroup and the nucleating species.

Controlled nucleation and growth of surface-confined gold nanoparticles on a (3-aminopropyl)trimethoxysilane-modified class slide: A strategy for SPR substrates

The thickness of the gold film and its morphology, including the surface roughness, are very important for getting a good, reproducible response in the SPR technique. Here, we report a novel alternative approach for preparing SPR-active substrates that is completely solution-based. Our strategy is based on self-assembly of the gold colloid monolayer on a (3-aminopropyl)trimethoxysilane-modified glass slide, followed by electroless gold plating. Using this method, the thickness of films can be easily controlled at the nanometer scale by setting the plating time in the same conditions. Surface roughness and morphology of gold films can be modified by both tuning the size of gold nanoparticles and agitation during the plating. Surface evolution of the Au film was followed in real time by UV-vis spectroscopy and in situ SPRS. To assess the surface roughness and electrochemical stability of the Au films, atomic force microscopy and cyclic voltammetry were used. In addition, the stability of the gold adhesion is demonstrated by three methods. The as-prepared Au films on substrates are reproducible and stable, which allows them to be used as electrodes for electrochemical experiments and as platforms for studying SAMs.

Controlled synthesis of L-lactide-b-epsilon-caprolactone block copolymers using a rare earth complex as catalyst

Well-defined block copolymers of L-lactide-b-epsilon-caprolactone were synthesized by sequential polymerization using a rare earth complex, Y(CF3COO)(3)/Al(iso-Bu)(3), as catalyst system. The compositions of the block copolymers could be adjusted by manipulating the feeding ratio of comonomers. The characterizations by GPC, H-1 NMR, C-13 NMR, and DSC displayed that the block copolymer, poly(epsilon-caprolactone-b-L-lactide) [P(CL-b-LLA)], had a narrow molecular weight distribution and well-controlled sequences without random placement.

Fabrication and characterization of orientation-controlled thin films of distyryl benzene derivatives

Distyryl benzene derivatives (DSB-1 and DSB-2) were deposited on a KBr (001) surface. DSB-1 molecules took two kinds of orientations depending on the substrate temperature. On the other hand, DSB-2 grew epitaxially. The longitudinal axes of DSB-2 molecules were oriented parallel to the substrate surface.

Probe beam deflection study on electrochemically controlled release of 5-fluorouracil

In this paper, the polypyrrole (PPy) film modified electrodes are used as an electroreleasing reservoir. The electrochemically controlled release of 5-fluorouracil (5-FU) from a PPy film modified electrode to aqueous electrolytes is studied by the in situ probe beam deflection (PBD) method combined with cyclic voltammetry (CV) and chronoamperometry (CA). The PBD results reveal that the release of 5-FU from PPy film depends on the electrochemical redox process of the PPy film electrode. The released amount is controlled by the reduction potential and is proportional to the thickness of the film. The exchange of 5-FU anions with Cl- on an open circuit is slow on the time scale of minutes, but the release of 5-FU anions can proceed quickly at -0.6 V (vs Ag/AgCl). The amount of released 5-FU decreases with the time that the PPy film is soaked in aqueous solution. (C) 1998 Elsevier Science Ltd. All rights reserved.

Liquid crystal alignment controlled by LB films

Copper phthalocyanine doped polymethacrylate Langmuir-Blodgett films were transferred to align a nematic liquid crystal 5CB, It is found that the pre-tilt angle of the liquid crystal can be controlled with the variation of the doped copper phthalocyanine molecular ratio and is correlated with the dichroic ratio of the aligning layer. The polarity of the aligning layer is regarded as the most likely underlying factor that causes the different LC alignment configurations. (C) 1997 Elsevier Science B.V.

ELECTROCHEMICAL CONTROLLED-RELEASE OF ADENOSINE-TRIPHOSPHATE

Polypyrrole (PPy) film was synthesized by anodic polymerization of pyrrole onto the surface of platinum electrode in the solution of sodium p-toluene sulfonate (NaTsO). When this film was oxidized anodically in an aqueous solution of adenosine triphosphatle (ATP), the ATP anions were incorporated into the film. Release of ATP From the film could be accomplished by reduction of the film in aqueous electrolyte solution. The total amount of ATP released from the film was determined by UV spectroscopic method.

FABRICATION OF STM TIPS WITH CONTROLLED GEOMETRY BY ELECTROCHEMICAL ETCHING AND ECSTM TIPS COATED WITH PARAFFIN

We have presented two simple methods of ''unfixed-position shield'' and ''pulling out'' for making sharp STM Pt-Ir tips with low aspect ratio by electrochemical etching in KCN/NaOH aqueous solution and ECSTM tips coated with paraffin. By limiting the elec

ELECTROCHEMICALLY CONTROLLED RELEASE OF ADENOSINE 5'-TRIPHOSPHATE FROM POLYPYRROLE FILM

Polypyrrole (PPy) film is synthesized by anodic polymerization of pyrrole onto the surface of a platinum electrode in the presence of toluene-p-sulfonate and the film is used for the controlled release of the neurotransmitter, adenosine 5'-triphosphate (ATP).

cDNA cloning and mRNA expression of the translationally controlled tumor protein (TCTP) gene from Japanese sea perch (Lateolabrax japonicus)

A homologue of the lower vertebrates translationally controlled tumor protein (TCTP) was cloned from the marine fish Japanese sea perch (Lateolabrax japonicus) by the technology of homology cloning. The full-length cDNA sequence of the sea perch TCTP gene contained a 5' untranslated region (UTR) of 47 bp, a 3' UTR of 433 bp, and a putative open reading frame (ORF) of 510 bp encoding a polypeptide of 170 amino acids. The deduced amino acid sequence of the sea perch TCTP gene showed a high similarity to that of zebrafish, rohu, rabbit, chicken and human. Sequence analysis revealed there were a signature sequence of TCTP family, an N-glycosylation site, and five Casein kinase phosphorylation sites in the sea perch TCTP. The temporal expression of TCTP genes in healthy and lipopolysaccharide (LPS) challenged fishes was measured by semi-quantitative reverse transcription-PCR (RT-PCR). The results indicated that LPS could up-regulate the expression of sea perch TCTP in the examined tissues, including head-kidney, spleen and liver.

Cultivation of the brown alga Hizikia fusiformis (Harvey) Okamura: controlled fertilization and early development of seedlings in raceway tanks in ambient light and temperature

Commercial cultivation of the dioecious brown macroalga Hizikia fusiformis (Harvey) Okamura in East Asia depends on the supply of young seedlings from regenerated holdfasts or from wild population. Recent development of synchronized release of male and female gametes in tumble culture provides a possibility of mass production of young seedlings via sexual reproduction. In this paper, we demonstrate that controlled fertilization can be efficiently realized in ambient light and temperature in a specially designed raceway tank in which the sperm-containing water has been recirculated. The effective fertilization time of eggs by sperm was found to be within six hours. Fast growth and development of the young seedlings relied on the presence of water currents. Velocity tests demonstrated that young seedlings of 2-3 mm in length could withstand a water current of 190 cm s(-1) stop without detachment. Culture experiments at 24 h postfertilization showed that elongation of both the seedlings and their rhizoids were not hampered by high irradiance up to 600 mu mol photons m(-2) stop s(-1) stop. However, growth was slightly retarded if cultured at a temperature of 16 degrees C compared to other culture temperatures of 22, 25 and 29 degrees C. No seedling detachment was observed after transfer of the young seedlings to raft cultivation in the sea after one and 1.5 months post-fertilization, indicating the feasibility of obtaining large quantity of seedlings in such a system.