Esso

About: Esso is a based out in . It is known for research contribution in the topics: Catalysis & Polymer. The organization has 3490 authors who have published 2850 publications receiving 62124 citations.

Thin Layer Chromatography

Abstract: The idea of using a chromatographic adsorbent in the form of a thin layer fixed on an inert rigid support seems to have been suggested by Izmailov and Shraiber in 1938. Meinhard and Hall[1] in 1949 developed this notion of an ‘open column’, and in 1951 Kirchner, Miller, and Keller[2] reported the separation of terpenes on a ‘chromatostrip’, prepared by coating a small glass strip with an adsorbent mixed with starch or plaster of Paris, which acted as a binder. The strips were handled in the same way that paper is handled in paper chromatography, and indeed the original object of the thin-layer technique was to apply the methods of paper partition chromatography to an adsorption system.

Estuarine facies models; conceptual basis and stratigraphic implications

Abstract: The nature and organization of facies within incised-valley estuaries is controlled by the interplay between marine processes (waves and tides), which generally decrease in intensity up-estuary, and fluvial processes, which decrease in strength down-estuary. All estuaries ideally possess a three-fold (tripartite) structure: an outer, marine-dominated portion where the net bedload transport is headward; a relatively low-energy central zone where there is net bedload convergence; and an inner, river-dominated (but marine-influenced) part where the net transport is seaward. These three zones are not equally developed in all estuaries because of such factors as sediment availability, coastal zone gradient and the stage of estuary evolution. Two distinct but intergradational types of estuaries (wave- and tide-dominated) are recognized on the basis of the dominant marine process. Wave-dominated estuaries typically possess a well-defined tripartite zonation: a marine sand body comprised of barrier, washover, tidal inlet and tidal delta deposits; a fine-grained (generally muddy) central basin; and a bay-head delta that experiences tidal and/or salt-water influence. The marine sand body in tide-dominated estuaries consists of elongate sand bars and broad sand flats that pass headward into a low-sinuosity ("straight") single channel; net sand transport is headward in these areas. The equivalent of the central basin consists of a zone of tight meanders where bedload transport by flood-tidal and river currents is equal in the long term, while the inner, river-dominated zone has a single, low-sinuosity ("straight") channel. These facies models and their conceptual basis provide a practical means of highlighting the differences and similarities between estuaries. They also allow the predication of the stratigraphy of estuarine deposits within a sequence-stratigraphic context.

Long Optical Paths of Large Aperture

Abstract: THE measurement of the vapor phase spectra T of compounds having high boiling points presents an experimental problem that may be solved either by heating the absorption cells or by making them very long. In the infra-red region radiation from the hot gases in heated cells decreases the accuracy of absorption measurements. If only a small amount of sample is available, the only possibility is to use an optical system in which the radiation goes back and forth through the same volume a large number of times. Several designs for such systems have been published recently1' 2 but none of them permits the use of large angular apertures at points off the optic axis. In this paper an absorption cell is described in which the light traverses a small volume a large and arbitrarily variable number of times, and in which the angular aperture of the mirrors is not occulted either on or off the optical axis. The design gives very high light transmission and can be used for observing spectra that are very weak, or that belong to high boiling point compounds or to compounds obtainable only in very low concentrations. It can be used for any liquids or gases that do not injure the mirror surfaces, with which they are directly in contact. The essential parts of the equipment are three spherical, concave mirrors that all have the same radius of curvature. These are set up as shown in Fig. 1 with two mirrors A and A' close together at one end of the absorption cell, and the third mirror B at the other end. The centers of curvature of A and A' are on the front surface of B, and the center of curvature of B is halfway between A and A'. This arrangement establishes a system of conjugate foci on the reflecting surfaces of the mirrors, by which all the light leaving any point on A is brought to a focus by B at the corresponding point on A', and all the light leaving this point on A' is focused back again to the

The role of serum haemagglutination-inhibiting antibody in protection against challenge infection with influenza A2 and B viruses.

Abstract: The intranasal inoculation of volunteers with living partially attenuated strains of influenza A and B viruses offers a new opportunity to determine the protective effect of serum haemagglutin-inhibiting antibody against a strictly homologous virus, under conditions where the time and dosage of the infective challenge can be controlled, the scoring of proven infections can be more precise and higher rates of infection can be achieved than in most natural epidemics.In 1032 adult volunteers, whose serum HI antibody titre was determined immediately before virus challenge, there was a consistent inverse quantitative relationship between the HI titre and the likelihood of infection. The PD 50 (50% protective dose) of HI antibody was 1/18-1/36, but an unusual finding was that volunteers with no detectable pre-challenge antibody often seem to be less susceptible to infection than those with pre-challenge antibody in low titre.In one group of volunteers challenged with an influenza B strain there was no evidence that pre-challenge antibody titres against viral neuraminidase had any significant protective effect against challenge infection.

An empirical correlation of second virial coefficients

Abstract: A new correlation of second virial coefficients of both polar and nonpolar systems is presented. It uses the Pitzer-Curl correlation for nonpolar compounds, but in a modified form. The second virial coefficient of nonhydrogen bonding compounds (ketones, acetaldehyde, acetonitrile, ethers) and weakly hydrogen bonding compounds (phenol) is fitted satisfactorily with only one additional parameter per compound, which is shown to be a strong function of the reduced dipole moment. Two parameters are needed for hydrogen bonding compounds (alcohols, water), but for alcohols, one parameter has been kept constant and the other expressed as a function of the reduced dipole moment. The extension of the correlation to mixtures is satisfactory, direct, and involves only one coefficient per binary.