Search results for "Chemical engineering"

Relationship between microscopic and macroscopic structures of organic thin films for SHG

1993

The experiments described in this paper were undertaken in order to obtain information about the relationship between the structure and non-linear optical properties (second-harmonic generation) of organic thin films. For this purpose, two closely related dyes, diones and tetrones, were compared, both of which are shown to have large hyperpolarisabilities. Their microscopic properties are investigated by conformational analysis and electron diffraction. It could be shown that detailed knowledge about the structure and the adjacent neighbour packing can be obtained from conformational analysis and electron diffraction in order to understand the non-linear optical properties of the two dyes.

Contradicting Reports on Magnetic Properties of Layered Molecule-Based Material N(n-C3H7)4[FeIIFeIII(C2O4)3]

2003

The Phase Behaviour of Amphiphilic Monolayers

1991

Amphiphilic monolayers display a wealth of condensed phases. It is only recently that these have been widely recognised as being distinct, but they are in fact quite analogous to the well-known lamellar gel phases of bulk lyotropic and thermotropic mesogens. An understanding of these phases has proved to be important for controlling the defect structure of the monolayers used in the fabrication of Langmuir-Blodgett films. This understanding is being achieved by developments in a number of techniques, including X-ray diffraction and isotherm miscibility. The phase diagrams of the materials studied so far are all very closely related, lending new credibility to the principle of corresponding …

Der Einfluß von Trichlormethan auf die δ-Relaxation eines kristallin-flüssigen Seitenkettenpolymers

1986

Dielektrische Untersuchungen an flussig-kristallinen Polymeren, in denen die Flussigkristalleinheit in der Seitenkette angeordnet ist, wurden von 10 Hz bis 100 kHz bei unterschiedlichen Temperaturen durchgefuhrt. Es konnte gezeigt werden, das sowohl die Relaxationsfrequenz als auch die Geometrie der Absorptionskurven der δ-Relaxation (Reorientierung der Seitenkette infolge der segmentalen Beweglichkeit der Hauptkette) durch Zugabe von Trichlormethan verandert werden. Trichlormethan wirkt als Weichmacher. Bei langerer Lagerung verdunstet das Trichlormethan und die molekulare Beweglichkeit vermindert sich. Dielectric investigations on liquid-crystalline polymers with the liquid crystal unit p…

Deduction of the oxidation degree of the group A15 elements at the phthalocyanines on the basis of the Q band

2017

Synthesis And Sorptive Properties Of Dodecasil 1 H With An Acessible Pore System

1994

Abstract The synthesis of Dodecasil 1H was studied in the system SiO2/1-adamantylamine/NH3/water with the objective of controlling the particle size and the morphology of the crystals. Since nucleation occurs in a very early stage of the synthesis, the heating rate to the final temperature have a strong influence on both parameters. Using seed crystals and such a heating programme, the expensive template 1-adamantylamine can be reduced to so small amounts, that a nearly template free pore system is achieved. The emptiness of the pore system was demonstrated from adsorption measurement using He and H2.

Hydrogen bond mediated intermolecular magnetic coupling in mononuclear high spin iron(iii) Schiff base complexes: synthesis, structure and magnetic s…

2020

The crystal structure and magnetic properties of two mononuclear iron(III) Schiff base complexes, [FeL1(NCS)2] (1), HL1 = 2-[1-[[2-[(2-aminoethyl)amino]ethyl]imino]ethyl]phenol and [FeL2(N3)Cl] (2), HL2 = 2-(-1-(2-(2-aminoethylamino)ethylimino)ethyl)-4-methylphenol are reported. Each complex contains a Fe(III) ion surrounded by a N3O Schiff base ligand and two NCS− ligands (in 1) or one N3− and one Cl− ligands (in 2). The magnetic properties can be well reproduced with zero field splittings in the high spin S = 5/2 Fe(III) ions and weak intermolecular Fe–Fe interactions mediated by hydrogen bonds. This intermolecular antiferromagnetic interaction has been validated by using DFT calculations…

Deposition of Cu Nanoparticles on the Surface of Metallic Aluminum

2012

Deposition of Cu particles by electrolysis at constant electrode potential and by internal electrolysis methods was investigated. The composition of deposited material was confirmed by optical and scanning electron microscope methods. Combination of electrolysis at constant electrode potential with internal electrolysis method was found most effective for fabrication of nanoparticle arrays. Single crystalline Cu particles are fabricated by internal electrolysis, while polycrystalline ones obtained by combined chronopotentiometric and internal electrolysis methods. The formation mechanism of Cu nanoparticles is described.

Immunoanalytical approaches for the control of xenobiotics and biotoxins in food

2020

[ES] El control efectivo de la calidad y seguridad de los ali­mentos requiere de métodos analíticos que garanticen la deter­minación fiable de cualquier sustancia potencialmente perjudicial para el consumidor que pueda estar presente en el alimento antes de su distribución y comercialización. Una de las aproximaciones analíticas que contribuye a garantizar este objetivo engloba una serie de técnicas que tienen en común la utilización de anticuerpos como elementos esenciales para la detección del analito diana, y que en conjunto reciben el nombre de métodos inmunoquímicos. Este artículo pretender aportar una visión básica de los principios bioquímicos subyacentes a estas tecnologías y cuáles…

Thermal frontal polymerization with a thermally released redox catalyst

2012

ABSTRACT: We studied thermal frontal polymerization using a re-dox systeminan attempt to lower the temperature of thefrontallypolymerizable system while increasing the front velocity so as toobtain a self-sustaining front in a thinner layer than without theredox components. A cobalt-containing polymer with a meltingpoint of 63 C (Intelimer 6050X11) and cumene hydroperoxidewere used with a triacrylate. The use of the Intelimer decreasedthe front velocity but allowed fronts to propagate in thinner layersand with more filler while still having a pot life of days. Nonplanarmodes of propagation occurred. Fronts propagated faster when6-O-palmitoyl- L -ascorbic acid was used as a reductant. Intere…