Search results for "Monolayer"

Superparamagnetic iron oxide/oleic acid nanoparticles with immobilized organosilicon derivatives ofN-(2-hydroxyethyl)tetrahydroisoquinoline: synthesi…

2013

Superparamagnetic iron oxide/oleic acid nanoparticles bearing lipid-like organosilicon N-(2-hydroxyethyl)-1,2,3,4-tetrahydroisoquinoline derivatives have been synthesized with the aim of their potential biomedical application. X-ray diffraction analysis, Dynamic light-scattering measurements, method of magnetogranulometry and some others have been employed to investigate the morphology and properties of the nanoparticles synthesized. The magnetic core diameter of mixed covered nanoparticles ranged between 4.8 and 9.6 nm. The magnetization analyses showed that the particles are superparamagnetic at room temperature. In vitro cell cytotoxicity and intracellular NO generation caused by the wat…

Real-space observation of xenon adsorption and desorption kinetics on graphite (0001) by photoemission electron microscopy

2003

Abstract The growth and desorption of Xe monolayers on the basal plane of graphite has been investigated by real-space imaging using photoemission electron microscopy. Adsorption kinetics was studied at different substrate temperatures (39–65 K), corresponding to different growth modes. Coexisting phases showed up as different grey values in the image. Typical domain sizes of the 2D solid phases around 60 K are of the order of one to several μm. The domains exhibit an elongated shape with their long axis oriented preferentially parallel to step edges of the substrate. With increasing coverage the brightness of the domains increases, the 2D gas-phase regions shrink and finally disappear at h…

Probing DNA conductivity with photoinduced electron transfer and scanning tunneling microscopy.

2012

Abstract The possibility that the stacked DNA bases can mediate vectorial electron transfer has been examined using two different approaches. Experiments on photoinduced electron transfer with intercalated donors and acceptors (either randomly bound or linked dyads of ruthenium complex and viologen) indicate that while DNA may be a better medium than acetonitrile for electron transfer over short distances (2-3-base pair, equivalent to 10-14Å centre-to-centre separation), it is a poor medium for transport over larger separations. Attempts to measure conductivity of individual DNA molecules using scanning tunneling microscopy to image mixed monolayers of mercaptohexanol (MCH) and 30-mer or 10…

Measuring the Contact Angle of Individual Colloidal Particles.

1998

The aim of this study was to measure the contact angles of individual colloidal spheres ( solidus in circle 4.4 µm) and compare it to contact angles obtained on similarly prepared planar surfaces. For this purpose the particles were attached to atomic force microscope cantilevers. Then the force between the particle in aqueous medium and an air bubble was measured versus the distance. From the resulting force curves we obtained contact angles and detachment forces of single particles. Contact angles of gold coated silica particles were adjusted between 20 degrees and 100 degrees by self-assembling monolayers from different mixtures of undecanethiols and omega-hydroxy undecanethiols from sol…

Atomistic Modeling of a New Storage

2008

It was observed that Me/Li2O and Me/LiF nanocomposites (Me is a metal that does not alloy with lithium) are able to exhibit an extra Li storage typically beyond the uptake of stoichiometric Li in the potential window 1.2 0.02 V, with pseudo-capacitive behavior and high-rate performance. Among the composites, the Ru/Li2O exhibits a high extra Li storage at this low potential. Moreover, the Li2O matrix allows one a higher storage in contact with transition metal than the LiF matrix [1,2]. To clarify the mechanism of the Li interfacial storage anomaly, we have performed comparative first principles calculations on the atomic and electronic structure of polar Ti/Li2O(111) and nonpolar Cu/LiF(00…

Dual-emitting Langmuir-Blodgett film-based organic light-emitting diodes.

2010

Langmuir-Blodgett (LB) films containing alternating layers of the metallosurfactants bis(4,4'-tridecyl-2,2'-bipyridine)-(4,4'-dicarboxy-2,2'-bipyridine) ruthenium(II)-bis(chloride) (1) and bis[2-(2,4-difluorophenyl)pyridine](4,4'-dinonadecyl-2,2'-bipyridine)iridium(III) chloride (2) have been prepared. Langmuir monolayers at the air-water interface of 1 and 2 with different anions in the subphase have been characterized by pi-A compression isotherms and Brewster angle microscopy (BAM). The transferred LB films have been characterized by IR, UV-vis and emission spectroscopy, and atomic force microscopy (AFM). Electroluminescent devices formed by LB films containing alternating layers of thes…

Molecular organization via ionic interactions at interfaces. 1. Monolayers and LB films of cyclic bisbipyridinium tetracations and dimyristoylphospha…

1993

Synthesis and properties of chemically modified dihydroxy-, hydroxyamino- and amino-functional silica packings in adsorption chromatography

1980

1,2-Dihydroxy-3-propoxypropyl (HPP), 1-amino-2-hydroxy-3-propoxypropyl (AHP) and 3-(2-aminoethylamino)propyl (AEAP) silica packings were synthesized by means of both a surface modification and a bulk modification procedure. In surface modification a complete monolayer of bonded groups could be achieved. The modifiers reacted with the silanol groups according to a bifunctional mechanism. Eluotropic series of solvents were established on these polar modified silicas referring to n-heptane having ɛ∘=0. The solvent parameter ratio of modified to bare silica was found to be constant over a wide range of solvent compositions as \(\varepsilon _{{\text{HPP - silica}}}^ \circ = 0.26\varepsilon _{{\t…

Adsorption of proteins on porous and non-porous poly(ethyleneimine) and tentacle-type anion exchangers

1990

Abstract Adsorption isotherms of proteins [bovine serum albumin (BSA), soybean trypsin inhibitor and alcohol dehydrogenase] on anion exchangers were measured by on-line and off-line methods. The poly(ethyleneimine) (PEI) type and the tentacle-type materials exhibited principally different modes of adsorption. On thin layers of PEI, bonded to non-porous silica, BSA adsorption data corresponded to a monolayer of molecules, with 80% adsorbed side-on, with a high affinity constant for binding, and 20% adsorbed more weakly. With porous material, the amount of BSA bound per unit surface with high affinity was smaller. With tentacle-type anion exchangers, adsorption exceeded a monolayer by far, an…

EFFECT OF SURFACTANT AND SUBSTRATE TEMPERATURE ON THE GROWTH OF Ag FILMS ON A SAPPHIRE SURFACE

1997

The possibility of modification of the thin film growth on an insulating (sapphire) substrate by using a Ga monolayer as a "surfactant" was studied. We found that the films grown in this way are electrically conducting and can emit photoelectrons at much lower thickness than those deposited on a pure substrate. The surfactant stabilizes the positions of Ag atoms on the substrate surface and inhibits the coalescence of small nuclei into bigger islands, even when the film is annealed to 450 K. This fact may be very important for thin metal film technology.