18 research outputs found

    Morphological features of distribution of branches of the ethmoid arteries on from the shape of the orbit

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    To study the topography of the lattice of the arteries of the labyrinth and their relationship to the form of the orbit was carried out anthropometric measurements by the method of V. N. Shevkunenko, A. M. Eselevich, T. V. Zolotareva, G. N. Toporov. To determine the shape of the orbit was measured by the following parameters: 1 - the height of the entrance to the eye socket - the distance between the upper and lower walls of the orbit; 2 - entrance width - the distance between the inner and outer walls of the orbit; 3 - the depth - the distance between the inner boundary of the entrance into the orbit to the optic canal

    An X-Ray Diffraction Study of the Conformation of the Cellulose Chain

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    Small angle neutron and X-ray scattering study of the formation and structure of micelles of CTAB in formamide

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    Small angle neutron and X-ray scattering was used to study micellization of cetyltrimethylammonium bromide (CTAB) in partially deuterated or hydrogenated formamide from the absolute values of scattered intensities,). Highly charged aggregates of around 6 monomers were observed at CTAB concentrations above the cmc (2.8 % wt at 60 ^{\circ}C). These aggregates along with spherical particles (2 nm radius) containing 29 monomers were consistently observed at concentrations above 8 %. These particles were considered to be micelles as they had similar structure, albeit of smaller size to those observed in water (2.7 nm, aggregation number 90). They also had a higher charge in formamide than in water (degree of ionization 0.55 in formamide and 0.14 in water). With increase in surfactant concentration, the micelles elongated, although the radius of the cylinders in the two dimensional hexagonal phase remained close to 2 nm. The importance of interactions of polar head with solvent molecules of high dipole moment and dielectric constant is discussed. The less spontaneous self-association of surfactant molecules in formamide than in water poses the problem of the cmc

    Etude par diffusion centrale des neutrons de la formation et de la structure des micelles de tensioactifs cationiques dans le formamide

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    We report here a study of the micellization of different surfactants to observe the effects of the chain length, counterions and headgroups in a non-aqueous polar solvent-formamide. Small-angle neutron scattering measurements were performed in a PACE spectrometer in L.L.B. The solvent used was a 2/3 deuterated formamide. The aggregation number and the spontaneity of the association depend on the chain length ; but, in formamide, micelles always are smaller and more ionized than in water. Their growth is much more low in formamide than in water where "rod-like micelles" form especially with Br". Cl- in formamide leads preferentially to the formation of small micelles as it does in water. The micellar ordered phase is observed in the binary C16 Py Cl/formamide system at high concentration. With regard to the headgroup N+(CH3)3, the pyridinium ring encouraged the micellization in formamide close to 20°C

    Micellization of N

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