Tunable ordered droplets induced by convection in phase-separating P2VP/PS blend film

Ordered hexagonal droplets patterns in phase-separating polymeric blend films of polystyrene and poly(2-vinylpyridine) (PS/PVP) formed due to the convection effect by solvent evaporation. The influences of PS molecular weight, solvent evaporation rate, and the weight ratio of PS to PVP on the PVP-rich domains pattern formation and distributions were investigated by atomic force microscope (AFM). Only in an appropriate range of molecular weight of PS, can the ordered pattern form. Too low or too high molecular weight of PS led no ordered pattern due to the viscosity effects. The increase of solvent evaporation rate decreased the mean radius of the PVP-rich domains and the intervals between the centers of the domains due to the enhancement of the viscosity on the top layer of the fluid film. The increase of the weight ratio of PS to PVP decreased mean radius of the PVP-rich domains whereas the intervals between the centers of droplets remained constant. Therefore, the size and the distributions of ordered patterns can be tuned by the polymer molecular weight, the weight ratio of the two components and the solvent evaporation rate.

In-situ FTIR spectroelectrochemical investigation of cobalt(II)-cyanoferrate polymeric film coated on a glassy carbon electrode

Cobalt(II)-cyanoferrate polymeric film has been electrochemically deposited on a glassy carbon electrode and investigated by cyclic voltammetry and in-situ reflection FTIR spectroscopy. A reorientation of the terminal C=N groups upon redox reactions was proposed. The stretching vibration mode of the terminal C=N groups associated with Fe(III) was observed at 2122 cm(-1), however, the stretching vibration mode for terminal groups associated with Fe(II) did not appear. This process could result in a switch between lattice-closed and lattice-opened surface structure. (C) 1997 Elsevier Science B.V.

THE EFFECT OF FILM-FORMING CONDITIONS FOR TAPCUPC LANGMUIR-BLODGETT-FILMS ON MORPHOLOGY AND PROPERTIES

The dependence of morphology and properties on film-forming conditions is described for the symmetrically substituted copper tetra-4-(2, 4-di-t-amylphenoxy) phthalocyanine (tapCuPc) Langmuir-Blodgett (LB) films. The effects of LB film-forming conditions (such as the surface pressure, pH value and the concentrations of spreading solutions) on film quality were studied with the help of a UV-visible spectrophotometer and a transmission electron microscope. Transmission electron microscopy photographs of the surface morphology of tapCuPc LB films show that a smooth and homogeneous surface structure can be obtained under optimum film-forming conditions.

ELECTROCATALYSIS ON ELECTROCHEMICALLY PRETREATED GLASSY-CARBON ELECTRODE

The surface structure of glassy carbon electrode subjected to "galvanostat" pretreat- ment and its electrocatalytic behaviour in the presence of ascorbic acid, catechol and hydroquinone were studied by means of cyclic voltammetry, chronoamperometry, chronocoulometry and scanning electron microscopy. The electrocatalytic mechanism was discussed, which was due to the adsorption and the catalysis of functional groups at the electrode surface. Three separated peaks from the mixture of catecnol, hydroq...

Effect of ultraviolet irradiation on sperm of the left-eyed flounder, Paralichthys olivaceus

In this study, at proper dosage of ultraviolet (UV) irradiation (180 sec: 36,000 erg/mm(2)), sperm chromosomes of left-eyed flounder, Paralichthys olivaceus, were inactivated, while spermatozoa maintained ability to move and inseminate eggs. Gynogenetic haploids were detected by morphological observation, chromosome counting, and flow cytometer analysis. The ultrastructure of treated sperm was observed under scanning electronic microscope (SEM) and transmission electronic microscope (TEM). The results showed that after being irradiated at lower dosage of irradiation (0-180 sec: 0-36,000 erg/mm(2)), the surface structure of spermatozoa was not affected by UV irradiation, while the inner structures including membrane system and karyoplasm denseness of treated spermatozoa were little changed. However, obvious changes were observed in their membrane system, mitochondria, and nucleus if the dosage of irradiation increased to 240 sec: 48,000 erg/mm(2) or 300 sec: 60,000 erg/mm(2). The sperm survival rates did not change at the lower dosages of the UV irradiation (0-180 sec: 0-36,000 erg/mm(2)) but decreased as the irradiation dosage increased. The motility of treated sperm was lower than that of control group in general but did not change with UV irradiation dosage increasing at the certain range of 0-300 sec: 0-60,000 erg/mm(2).

Comparative study by infrared spectroscopy and microcalorimetry of the CO adsorption over supported palladium catalysts

The adsorption of CO on Al(2)O(3), ZrO(2), ZrO(2)-SiO(2), and ZrO(2)-La(2)O(3) supported Pd catalysts was studied by adsorption microcalorimetry and infrared (TR) spectroscopy. Some interesting and new correlations between the results of microcalorimetry and IR spectroscopy have been found. The CO is adsorbed on palladium catalysts in three different modes: multibonded (3-fold), bridged (2-fold), both on Pd(lll) and (100) planes, and linear (1-fold) adsorbed species. The corresponding differential adsorption heats lie in the field of high (210-170 kJ/mol), medium (140-120 kJ/mol), and low (95-60 kJ/mol) values, respectively. The nature of the support, the reduction temperature, and the pretreatment conditions affect the surface structure of the Pd catalysts, resulting in variations in the site energy distribution, i.e., changes in the fraction of sites adsorbing CO with specific heats of adsorption. Moreover, the CeO(2); promoter addition weakens the adsorption strength of CO on palladium. Based on the exposed results, a correctness factor, which considers the percentages of various CO adsorption states, must be introduced when one calculates the Pd dispersion using CO adsorption data.

FTIR study of CO and NO adsorbed on nitrided CoMo/Al2O3 catalysts

The states of surface Co and Mo sites on nitrided CoMo supported on Al2O3 were studied by adsorption of CO and NO as IR probe molecules. Three IR bands at 2200, 2060 and 2025 cm(-1) were detected for adsorbed CO. These bands can be respectively attributed to the surface NCO species as a result of CO adsorbed on surface N sites, and linearly adsorbed CO on surface Co and Mo sites in low valence states. The addition of cobalt to the Mo nitride diminishes the band at 2200 cm(-1). This may be due to either the change of the surface structure of the supported nitride, or the formation of a new phase, CoxMoyNz, as suggested in the literature Kim et al., Catal. Lett., 1997, 43, 91 and Logan et al., Catal. Lett., 1998, 56, 165. Comparison of CO and NO adsorption on Mo2N/Al2O3 and CoMoNx/Al2O3 indicates that the presence of cobalt can promote the reduction and nitridation of Mo.

The Representation of Image Texture

This thesis explores how to represent image texture in order to obtain information about the geometry and structure of surfaces, with particular emphasis on locating surface discontinuities. Theoretical and psychophysical results lead to the following conclusions for the representation of image texture: (1) A texture edge primitive is needed to identify texture change contours, which are formed by an abrupt change in the 2-D organization of similar items in an image. The texture edge can be used for locating discontinuities in surface structure and surface geometry and for establishing motion correspondence. (2) Abrupt changes in attributes that vary with changing surface geometry ??ientation, density, length, and width ??ould be used to identify discontinuities in surface geometry and surface structure. (3) Texture tokens are needed to separate the effects of different physical processes operating on a surface. They represent the local structure of the image texture. Their spatial variation can be used in the detection of texture discontinuities and texture gradients, and their temporal variation may be used for establishing motion correspondence. What precisely constitutes the texture tokens is unknown; it appears, however, that the intensity changes alone will not suffice, but local groupings of them may. (4) The above primitives need to be assigned rapidly over a large range in an image.

The role of Sn in Pt-Sn/CeO2 catalysts for the complete oxidation of ethanol

The structural features and catalytic properties of Pt-Sn/CeO2 catalysts prepared by modified polyol method were extensively investigated for the complete oxidation of ethanol. CO chemisorption, TPR, DTA and XPS measurements identically indicated that the electronic configuration of Pt by Sn as well as the formation of PtSn alloy were the key factors in determining the nature of the active sites, A strong Pt/Sn atomic ratio dependence of catalytic perfortmances was observed. which was explained in terms of the change., in the Surface structure of metal phases and the electronic Pt-Sn interaction. (c) 2005 Elsevier B.V. All rights reserved.

Effects of Highlights on Gloss Perception

The perception of a glossy surface in a static monochromatic image can occur when a bright highlight is embedded in a compatible context of shading and a bounding contour. Some images naturally give rise to the impression that a surface has a uniform reflectance, characteristic of a shiny object, even though the highlight may only cover a small portion of the surface. Nonetheless, an observer may adopt an attitude of scrutiny in viewing a glossy surface, whereby the impression of gloss is partial and nonuniform at image regions outside of a higlight. Using a rating scale and small probe points to indicate image locations, differential perception of gloss within a single object is investigate in the present study. Observers' gloss ratings are not uniform across the surface, but decrease as a function of distance from highlight. When, by design, the distance from a highlight is uncoupled from the luminance value at corresponding probe points, the decrease in rated gloss correlates more with the distance than with the luminance change. Experiments also indicate that gloss ratings change as a function of estimated surface distance, rather than as a function of image distance. Surface continuity affects gloss ratings, suggesting that apprehension of 3D surface structure is crucial for gloss perception.

Souterrain in Grallagh Lower Td. Co. Waterford

A souterrain was discovered here when the weight of a tractor passing overhead caused a collapse of the roof of Chamber I. It was surveyed in March 1976. The landowner, Mr. Thomas Curran of Ballylangdon has consented to keep the site open for future inspection. The site is not directly connected with any visible surface structure. A small uni-vallate ringfort is however situated c.I60m S.S.E. of the site. The bedrock is a slaty sandstone.

Reactivity of sub 1 nm supported clusters: (TiO2)(n) clusters supported on rutile TiO2 (110)

Metal oxide clusters of sub-nm dimensions dispersed on a metal oxide support are an important class of catalytic materials for a number of key chemical reactions, showing enhanced reactivity over the corresponding bulk oxide. In this paper we present the results of a density functional theory study of small sub-nm TiO2 clusters, Ti2O4, Ti3O6 and Ti4O8 supported on the rutile (110) surface. We find that all three clusters adsorb strongly with adsorption energies ranging from -3 eV to -4.5 eV. The more stable adsorption structures show a larger number of new Ti-O bonds formed between the cluster and the surface. These new bonds increase the coordination of cluster Ti and O as well as surface oxygen, so that each has more neighbours. The electronic structure shows that the top of the valence band is made up of cluster derived states, while the conduction band is made up of Ti 3d states from the surface, resulting in a reduction of the effective band gap and spatial separation of electrons and holes after photon absorption, which shows their potential utility in photocatalysis. To examine reactivity, we study the formation of oxygen vacancies in the cluster-support system. The most stable oxygen vacancy sites on the cluster show formation energies that are significantly lower than in bulk TiO2, demonstrating the usefulness of this composite system for redox catalysis.

CO oxidation on Pd(100) and Pd(111): A comparative study of reaction pathways and reactivity at low and medium coverages

We have performed density functional theory calculations with the generalized gradient approximation to investigate CO oxidation on a close-packed transition metal surface, Pd(lll), and a more open surface, Pd(100), aiming to shed light on surface structure effects on reaction pathways and reactivity, an important issue in catalysis. Reaction pathways on both surfaces at two different coverages have been studied. It is found that the reaction pathways on both surfaces possess crucial common features despite the fact that they have different surface symmetries. Having determined reaction barriers in these systems, we find that the reaction on Pd(lll) is strongly coverage dependent. Surface coverages, however, have little effect on the reaction on Pd(100). Calculations also reveal that the low coverage reactions are structure sensitive while the medium coverage reactions are not. Detailed discussions on these results are given.

Deposit-feeding mechanisms and resource partitioning in tropical holothurians

Aspidochirote holothurians found on tropical reef flats feed on particulate deposits which form a variety of substrata. The synaptid holothurian Opheodesoma grisea (Semper) feeds in a similar manner by scraping deposits from the surfaces of sea grasses. Distributional and gut content analyses showed that species partitioning is on the basis of substratum and particle size preference. Scanning electron microscopy revealed that the tentacles of aspidochirotes have a nodular surface while those of O. grisea have a tessellated surface structure. The twelve different species examined were shown to have different tentacular surface textures which bore an apparent relationship with the mean particle sizes selected by the different species. Light microscope studies of tentacle sections confirmed earlier observations on the extent of the water vascular system in aspidochirote and pinnate tentacles. From these observations a functional interpretation is proposed for tentacular operation and the means of particle selection in such holothurians.

Immunochemical characterization of a polysaccharide antigen of Bacteroides fragilis with an IgM monoclonal antibody

An IgM mouse monoclonal antibody (McAb) Bf4 was produced to a surface polysaccharide of Bacteroides fragilis NCTC 9343. Immunoblotting showed that McAb Bf4 reacted strongly with a high molecular mass structure which was sensitive to oxidation with periodate but resisted protease treatment. An inhibition enzyme-linked immunosorbent assay (ELISA) indicated that McAb Bf4 did not cross react with the sixteen Bacteroides species and strains tested. Cells of B. fragilis NCTC 9343 recovered from the various interfaces of a Percoll discontinuous density gradient were tested in the inhibition ELISA. Bacteria from the 0-20%, 20-40% and 40-60% interfaces inhibited the ELISA; however, cells from the 60-80% interface did not. Electron microscopy with immunogold labelling showed that McAb Bf4 did not react with the extracellular fibrous network on bacteria recovered from the 0-20% interface, or the extracellular electron dense layer on cells from the 60-80% interface; however, it was associated with a surface structure on cells from the 20-40% interface. Growth in vivo did not enrich for bacteria with this structure.