Determination of Chemical Composition of Commercial Rose Bengal Preparations by Chemical and Biological Methods

The method of the fraction separation in commercial rose bengal has been described. Individual fractions were identified on the basis of the absorption maxima obtained on a spectrophotometer. Iodine labelled rose bengal was used for biological investigation in the experimental animals. It was found that rose bengal produced by Durand contains a high percentage of the main component of tetraiodotetrachlor-fluoresceine (absorption maxima at 548 nm) and is therefore most suitable for the labelling process.     

Critical properties of non-spherical molecule fluids from the virial expansion

Critical constants of pure fluids (as important reference data in constructing vapour-liquid phase diagrams and basic input of various estimation methods) were determined for systems of non-spherical Kihara molecules; values of the critical temperature, density, compression factor and pressure of fluids composed of prolate and oblate molecules were evaluated from the fourth-order virial expansion. The second and third virial coefficients of the Kihara molecules were determined by applying the recently proposed method in which the effect of molecular core geometry and functional dependence of a pair interaction on the surface-surface distance are factorized and the former contribution determined from a formula for the corresponding hard convex body virial coefficient. The virial expansion for non-spherical Kihara molecules is applied to determine the critical constants of n-alkanes (methane to octane) and cyclic hydrocarbons (cyclopentane, cyclohexane, benzene and naphthalene); a fair agreement with experimental data was found.     

Investigating the characteristics of the commercial gas tube ‘S10 Starter’ using a time-delay measuring method

The results of the commercial gas discharge tube investigation (starter ‘S10 Philips’), using the time-delay measuring method, are presented in this paper. This gas discharge tube is usually used as a starter, that is, for electrode heating regularization in fluorescent tubes. The measurements of time delay are performed for different voltages (from 210 V to 400 V) and different relaxation times (from 1 ms to 3 s). The obtained memory curves show that the used gas discharge tube has a very small memory effect, which indicates a fast response after a long (out-of-use) time. This characteristic of the used commercial gas discharge tube is a consequence of gas tube geometry. It also shows that the time-delay distributions for small relaxation time values have a Gaussian shape; with the increase in relaxation time the right tail of distributions increases and distributions lose symmetry and become exponential.     

Order-from-disorder effect in the exactly solved mixed spin-(1/2, 1) Ising model on fully frustrated triangles-in-triangles lattices

The mixed spin-(1/2, 1) Ising model on two fully frustrated triangles-in-triangles lattices is exactly solved with the help of the generalized star-triangle transformation, which establishes a rigorous mapping correspondence with the equivalent spin- 1/2 Ising model on a triangular lattice. It is shown that the mutual interplay between the spin frustration and single-ion anisotropy gives rise to various spontaneously ordered and disordered ground states, which differ mainly in an occurrence probability of the non-magnetic spin state of the integer-valued decorating spins. We have convincingly evidenced a possible coexistence of the spontaneous long-range order with a partial disorder within the striking ordered–disordered ground state, which manifests itself through a non-trivial criticality at finite temperatures as well. A rather rich critical behavior including the order-from-disorder effect and reentrant phase transitions with either two or three successive critical points is also found.     

Ferromagnetism in the two-dimensional Hubbard model with long-range hopping

The combination of small-cluster exact-diagonalization calculations and the quantum Monte Carlo method is used to examine ferromagnetism in the two-dimensional Hubbard model with a generalized type of hopping. It is found that the long-range hopping with exponentially decaying hopping amplitudes t _ij ～ ? q ^Ri?Rj stabilizes the ferromagnetic state for a wide range of electron interactions U and electron concentrations n > 1. The critical value of the hopping parameter q _c above which the ferromagnetic state becomes stable is calculated numerically and the ground-state phase diagram of the model is discussed for physically the most interesting cases.     

Merck's Success in the Japanese Liquid Crystal Market

Abstract

Liquid crystal displays are a key component of the information society. They are found in many places in cars, measurement equipment, portable computers, and portable communication equipment. A typical state-of-the-art active matrix colour liquid crystal display today has a diagonal of 10 in, 550 × 650 pixels, and costs about US$ 1200 each in industrial quantities. In many products the liquid crystal display is the dominant component in terms of value. Each pixel has it's own transistor control circuit which at the moment uses amorphous silicon thin film transistor (TFT) technology. Very soon, however, polycrystalline silicon will be used instead of amorphous silicon. Since polycrystalline silicon is the same as that used in ordinary silicon VLSI, all other electronic circuits including the CPU can then be integrated onto the substrate of the liquid crystal display. Therefore, very soon, the business of all those companies will be threatened, who at present purchase liquid crystal displays externally, and build a product around it (see also: IEEE-Spectrum, May 1995, pages 62–69).     

From realistic to primitive models: a primitive model of methanol

An attempt to develop a methodology to construct a primitive model which descends directly from a parent realistic short-range model and reproduces its structural properties has been made. The realistic three-site OPLS model of methanol has been chosen as a test case. The primitive model copies the geometry of the OPLS model and thus pictures the methanol molecule as a hard heteronuclear dumbbell (representing oxygen and carbon atoms) with one embedded hydrogen site. All sites interact as hard spheres with the exception of the oxygen-hydrogen pair which may form a hydrogen bond mimicked by a square-well attraction. To determine parameters of the model two routes have been followed: (i) theoretical, based on an effective sphericalized site-site potential obtained from the parent potential, and (ii) semitheoretical which makes use of the knowledge of the structure of the dense parent fluid. Both sets of parameters provide similar results and reproduce the structure (site-site correlation functions, distribution of H-bonds and H-bond geometry) of the parent OPLS fluid reasonably well.     

Ruthenium-tin sol-gel catalysts: effect of the preparation and tin precursor influence

The influence of the synthesis route and the chemical nature of tin precursors on the catalytic properties of supported sol-gel Ru-Sn/SiO₂ catalysts were studied. It was demonstrated that introduction of tin afforded better selectivities than a monometallic sol-gel catalyst in the liquid-phase hydrogenation of cinnamaldehyde; however, the chemical nature of the tin precursor did not influence the catalyst performance. Sol-gel catalyst properties depended significantly upon the preparation method used and on the activation temperature. The selectivity to unsaturated alcohol increased with conversion, which is indicative of the in-situ creation of active sites selective in the carbonyl bond hydrogenation.     

The synthetic fragrant compounds based on 2-tert-butylcyclohexanol

The reaction of 2-tert-butylcyclohexanol with dimethyl carbonate resulting in 2-tert-butylcyclohexylmethyl carbonate (1a) and di-(2-tert-butylcyclohexyl) carbonate (1b) was studied. A second part investigates the reactions of 2-tert-butylcyclohexanone (obtained by dehydrogenation of 2-tert-butylcyclohexanol) with diols resulting in the corresponding ketals. The sensoric and fragrant characteristics of the synthesized compounds were also described.