A HIGHLY REACTIVE HETEROATOM ANALOG OF RETINAL AND ITS INTERACTION WITH BACTERIORHODOPSIN

Abstract— C₁₈ formate ester (5) [2-(6-methyl-8-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3E,5E,7E-octatrienyl formate], a highly reactive analog of retinal, was synthesized and its interaction with bacterioopsin studied. The formate ester, in the absence of purple or bleached membrane, undergoes very rapid reaction (t_l/2= 0.9 min) in neutral buffer but with membrane present it diffuses more rapidly into the membrane where it reacts slowly. Incorporation of 5 in the membrane results in a 38 nm (3900 cm^-1) red shift which remains after reconstitution with retinal. Similar experiments with the corresponding C₁₈ alcohol (4) results in a red shift, but this absorption blue shifts upon reconstitution with retinal. Washing the formate ester-treated membrane with bovine serum albumin or the corresponding lyophilized preparation with hexane, treatments that remove retinal oxime, fails to remove the UV-visible absorption, suggesting that a covalent bond between the C₁₈ moiety and a nucleophilic group of the protein has probably formed.     

Strukturanalyse organischer Sulfide mit Hilfe der Gras-Chromatographie

Zusammenfassung Eine Methode der Identifizierung von Alkyl- und Arylgruppen organischer Sulfide wurde ausgearbeitet, die die Spaltung dieser Stoffe mit Raney-Nickel zur gaschromatographischen Bestimmung der dabei entstandenen Kohlenwasserstoffe ausnützt.

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Summary A method was developed for identifying alkyl- and aryl groups of organic sulfides. The method employs the cleavage of these materials with Raney nickel for the gas chromatographic determination of the resulting hydrocarbons.

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Résumé On a mis au point une méthode d'identification des groupes alkylés et arylés des sulfures organiques exploitant la dissociation de ceux-ci par le nickel Raney pour le dosage par chromatographic en phase gazeuse des carbures d'hydrogène qui se forment.

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Die Autoren danken den Kollegen Dr.M. Veea, Ing.J. Petránek und Ing.J. Gaspari für die Überlassung von Proben organischer Sulfide.     

Axial segregation of granular materials

When mixtures of granular materials are rotated, it is often found that they segregate into bands, along the axis of rotation, which are rich in the various components. This effect is discussed experimentally and theoretically, with emphasis on a mechanism based on surface flow. The complimentary phenomenon of radial segregation is reviewed, and a mechanism is proposed. Finally, we consider the long-time behavior of rotating mixtures, particularly their anomolous coarsening. (c) 1999 American Institute of Physics.     

Decidability results in non-classical logic. III

A Kripke type semantics is given to a large class of tense logics with statability operators (including PriorsQK _t) in such a manner as to obtain their decidability using Rabin’s theorem. Dedicated to the Memory of A. N. Prior     

The deBranges theorem and uniqueness statements

Recently deBranges gave a very remarkable proof of Milin’s conjecture. This implies both the conjectures of Robertson and Bieberbach. It is our aim to show that the statement of equality case in both Robertson’s and Bierbach’s conjectures may be proved by a different and easier method.     

Dynamic Contrast-Enhanced Imaging and Analysis at High Spatial Resolution of MCF7 Human Breast Tumors

High resolution, dynamic GdDTPA-enhanced images of MCF7 human breast tumors in immunodeficient mice were analyzed at pixel resolution. The analysis, based on a physiological model, was performed by applying a nonlinear least-square algorithm using a color coded scale. The final output mapped at pixel resolution capillary permeability times surface area and fraction of extracellular volume, for each tumor slice. In addition, the output included assessment of the fit to the model by determining the proportion of variability (R²) for each pixel. The spatial variation in theR²values served to identify regions where the predominant mechanism of enhancement was leakage from the intravascular volume to the extracellular volume (R²close to 1). In regions with lowR²other mechanisms of enhancement appear to be dominating presumably diffusion within the extracellular space. As expected, in necrotic regions lacking microcapillaries and identified by analyzingT₂-weighted images of the same tumors, the model failed to fit the dynamic contrast enhanced data. The heterogeneous distribution of the determined pathophysiological features demonstrates the importance of recording and analyzing breast tumor images at high spatial resolution.     

From crack deflection to lattice vibrations—macro to atomistic examination of dynamic cleavage fracture

A set of cleavage experiments with strip-shaped single-crystal silicon specimens subjected to three-point bending is reported. The experiments enabled examination of the relationships between the dynamic energy release rate, the velocity, the orientation-dependent cleavage energy, and the cleavage plane of propagation.Dynamic crack propagation experiments show that when a [0 0 1] silicon single crystal is fractured under three-point bending at ‘parallel’ velocity (directly measured at the bottom surface of the specimen) of up to , it prefers to cleave along the vertical (1 1 0) plane, while when the specimen is fractured under the same conditions but at a velocity higher than , it cleaves along the inclined (1 1 1) plane. At intermediate velocities, the crack will deflect from the (1 1 0) plane to the (1 1 1) plane. Crack velocity was determined by the initial notch length. The local (calculated) velocity of deflection between the cleavage planes ranges from , for a crack propagating on the (1 1 0) plane in the direction, to about , for a crack on the (1 1 0) plane, but in the [0 0 1] direction.It is suggested that the cause of the deflection phenomenon is the anisotropic, velocity-dependent cleavage energy, resulted phonon radiation caused by anisotropic, velocity-dependent lattice vibrations. We have studied the effect of material properties and propose selection criteria to explain the deflection phenomenon: the crack will deflect to the plane of least-energy, for which G−Γ_i(V)=max, or to the plane with maximum crack tip velocity, V_i(Γ)=max.     

Quasi-Values on Subspaces

Quasi-values are operators satisfying all axioms of the Shapley value with the possible exception of symmetry. We introduce the characterization and extendability problems for quasivalues on linear subspaces of games, provide equivalence theorems for these problems, and show that a quasi-value on a subspaceQ is extendable to the space of all games iff it is extendable toQ+Sp{u} for every gameu.Finally, we characterize restrictable subspaces and solve the characterization problem for those which are also monotone.     

On the Bieberbach conjecture for functions with a small second coefficient

In the following we prove that for a given univalent function such that |a ₂|<1.05, |a _n|<n for eachn. This is an improvement of the result in [1].     

An axiomatization of the egalitarian solutions

The egalitarian solutions for general cooperative games which were defined and axiomatized by Kalai and Samet, are compared to the Harsanyi solution. It is shown that axioms used by Hart to characterize the Harsanyi solution can be used to characterize the (symmetric) egalitarian solution. The only changes needed are the omission of the scale covariance axiom and the inclusion, in the domain of the solution, of games which lack a certain smoothness requirement.