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Synthese de [dioxo-7,10 octahydro anthracenyl-2]-10 (et [dihydro-4',7' dioxo-4',7' spirobi-2:2'-indanyl-5]-10-) diethyl-2,8 hexamethyl-3,7,8,12,13,18 porphyrines qui presentent une structure bloquee

The possibility of using precise astrometric observations of Martian satellites in 1988 for improving the mutual orientation of the dynamic and stellar reference frames is discussed. The results obtained lead to the conclusion that the stellar reference frame is rotated about the X axis of the dynamic one. However, the value of this rotation (~2.″5) proves to be unrealistically large and repetitions of precise observations of Martian satellites are needed in the future for verifying this result.

Quantum chemical calculations of simple potential energy maps for system composed of toluene and oxygen moieties are presented. Reaction pathways following from energy profiles for interaction between reagents in different mutual orientations are discussed.

The dependence of Forster long-range resonance energy transfer efficiency on the orientational freedom of donor D and acceptor A molecules attached to a macromolecular substrate is examined. The usefulness of polarized emission measurements in determining the mutual orientation as well as the degree of orientational freedom of D and A and thereby deriving maximum and minimum values for the D–A separation from the transfer efficieny is demonstrated.

Various grain boundaries were observed in KCl tablets produced by compressing the powder. A parameter c (individual confusion factor: ICF) was proposed to describe the mode of appearance of a grain boundary which is governed by the mutual orientation of the two adjacent grains. In the present paper, the ICF is defined by c=γ trg( \widehatEF,π/2), where γ is a parameter of the imperfection in the crystal particle, \widehatEF the angle between the direction E of the particle and the direction F of the stress, and trg means a triangular wave function. It is also shown that the above expression fits experimental data qualitatively.

Complex growth polytypic structures arising from evaporated solutions of n -C 28 H 58 (octacosane) in petroleum ether are described. Dihedral concave angle effect on the step velocity is discussed in detail as the key for the determination of the mutual orientation of two layers in twin position. Several periodic polysynthetic twins are described as growth phenomena generated by screw dislocations. The 〈110〉 twin laws are discussed in detail. An attempt is made to correlate the observed occurence of both complex polytypes and periodic polysynthetic twins with the conditions of crystallization.

(Z)-3β-Acetoxy- and (Z)-3 α-acetoxy-5, 10-seco-1 (10)-cholesten-5-one (6a) and (7a) were synthesized by fragmentation of 3β-acetoxy-5α-cholestan-5-ol (1) and 3α-acetoxy-5β-cholestan-5-ol (2), respectively, using in both cases the hypoiodite reaction (the lead tetraacetate/iodine version). The 3β-acetate 6a was further transformed, via the 3β-alcohol 6d to the corresponding (Z)-3β-p-bromobenzoate ester 6b and to (Z)-5, 10-seco-1 (10)-cholestene-3, 5-dione (8) (also obtainable from the 3α-acetate 7a). The 1H-and 13C-NMR. spectra showed that the (Z)-unsaturated 10-membered ring in all three compounds (6a, 7a and 8) exists in toluene, in only one conformation of type C1, the same as that of the (Z)-3β-p-bromobenzoate 6b in the solid state found by X-ray analysis. The unfavourable relative spatial factors (interdistance and mutual orientation) of the active centres in conformations of type C1 are responsible for the absence of intramolecular cyclizations in the (Z)-ketoesters 6 and 7 (a and c).

In the limit of small exciting light-pulse areas the amplitude and polarization of the tri-level photon echo in gases formed by the exciting pulses with arbitrary shapes are obtained. It is shown that the dependence of the tri-level photon echo signal on the mutual orientation of the exciting pulse polarization vectors may be used to determine the optical coherence-matrix relaxation characteristics for an optically forbidden transition. The conditions under which a tri-level photon echo pulse repeats the shape of each of the exciting pulses are defined. It is proved that the tri-level photon-echo polarization properties do not depend on the shapes of the exciting pulses, either for small light-pulse areas or for the tri-level echo formation on narrow spectral lines.

1. It is suggested that the diamond-graphite transitions can proceed either directly or through intermediate metastable phases. 2. The conditions required for thin-layer graphite-to-diamond transition are determined by the depth and mutual orientation of the layers.

Extended Huckel calculations have been performed on a number of C3H6 complexes with a linear O−Cu−O fragment. The influence of the mutual orientation of C3H6 and the Cu2 O fragment in hypothetic surface complexes upon the energy of the system and electron density distribution has been determined. The role of these complexes in catalysis is discussed.

For monograins of Al-Al 2 Cu with two mutual orientations, misorientations Δϕ o between lamellar blocks have been evaluated and distance D between mismatch boundaries has been measured. D increases in a monotonous way with λ and is a function of mutual orientation, while Δϕ o decreases with λ and is not a function of mutual orientation. Experiments show no significant influence of thermal gradient on D and Δϕ o .

The mutual rotational orientation of the three hexon polypeptide subunits of the peripentonal hexons has been determined in relation to each other, to the penton and to the neighbouring hexons. The possible mutual orientation of all the polypeptide subunits of the adenovirus-building hexon capsomers are presented on a tentative virus model.

Ag3BO3-II, eine Stapelvariante von Ag3BO3-I, kristallisiert mit a = 987,8(3); c = 1351,2(6) pm in R3c. Strukturbestimmung und Parameterverfeinerung auf der Basis von 376 Reflexen (Diffraktometerdaten) fuhrten zu einem konventionellen R-Wert von 0,035. Die Silberteilstrukturen und die Positionen der Boratanionen sind in beiden Formen von Ag3BO3 gleich. Eine unterschiedliche gegenseitige Orientierung der BO3-Gruppen bewirkt eine Aufweitung des OAgO Valenzwinkels von 143° (Form I) auf 178° (Form II). Ag3BO3-II, a New Form of Silver(I)-orthoborate Ag3BO3-II [a = 987.8(3), c = 1351.2(6) pm, R3c] is a stacking variant of Ag3BO3-I. Determination of the crystal structure (376 diffractometer data) lead to R = 0.035. The silver partial structure as well as the positions of the borate-anions are identical in both forms of Ag3BO3. Different mutual orientation of the BO3 groups results in increased angles OAgO in form (II) (178°) compared to 143° in Ag3BO3-I.

Internal defects and twin structures exist in thermally transformed monoclinic (m)-ZrO2 particles confined in a mullite matrix. The defects were analyzed by transmission electron microscopy. Twin boundaries on (100), (110), (001), and (011) were found. Frequently, (100) and (110) twins formed complicated mosaiclike structures. Some particles could be divided into two or more twinned sections with well-defined mutual orientation relations. Domains of closure were observed at the particle-matrix interface. The observations are discussed in terms of a simple model which considered (i) the anisotropic volume increase of ZrO2 during the t→m transformation, (ii) the anisotropic thermal expansion coefficient of ZrO2, and (iii) the rather isotropic thermal expansion coefficient of the mullite matrix.

The relative orientation of benzene and aromatic ring planes in condensed phases of organic compounds is examined. Directional preferences are analyzed in terms of electrostatic and dispersion-repulsion empirical formulations. The atomic charge model is reviewed, particularly the definition of charges and their use in empirical potentials. Data are presented on the distribution of interatomic contact distances and on the orientation of benzene rings in hydrocarbon crystals; interplanar angles between 10° and 30° are not preferred, but not entirely forbidden. The forces are simple to model, but their interplay for complex molecules is not easily understood.

Organic luminophores of the azlactone series that contain a strong electronacceptor substituent, viz., a difluoromethylsulfonyl group, were synthesized. The significant effect of the electronic nature of the substituents on the frequencies of the stretching vibrations of the CO and C=N groups was demonstrated, and the trans configuration of the investigated compounds was confirmed. The introduction of a difluoromethylsulfonyl group in the azlactone molecule promotes the development of intense fluorescence in solutions at room temperature. The character of the substituents and their mutual orientation have a substantial effect on the optical characteristics.

[2.2](2,5)Pyridinophanes 1 – 4 consisting of two nicotinic ester units in the four different orientations possible were synthesized. Diquaternization to the corresponding pyridiniophanes 9 – 12 and partial reduction of 9 and 12 yielded the semi-reduced species 14 and 15; these isomers, due to their different mutual orientation of pyridinium and 1,4-dihydropyridine units, are of interest with regard to intramolecular redox reactions.

Critical cooling rates (CCR) are calculated by means of the original model. The model allows to relate CCR with glass forming conditions and the structure of glass with its thermal prehistory as well. The mechanism of the initial stage of crystallization seems to be connected with the change of mutual orientation of some structure groups in the process of their elastic vibrations, their frequency being V o ⋍ IO II sec−I. Reorientation is accompanied by bonds switching. The activation energy of this process is assumed to be initial reorientation barrier ΔG# which was introduced earlier (I).

We have investigated the dependence of the efficiency of electron tunneling between planar cyclic molecules on their mutual orientation. An expression has been obtained for the dependence on orientation of the tunneling probability in terms of the “cyclic polyene” model. The magnitude of the orientation effect has been estimated for a change in the orientation of the molecules from the face-to-face to the edge-to-edge position.

The two longest wavelength electronic transitions of the quinhydrones 1 and the dependence of transition energies and intensities on the mutual orientation of hydro-quinone and p-benzoquinone is studied within semiempirical π-theory. The results are in good agreement with the experimental UV-VIS spectra of closely related cyclophane-quinhydrones. The study is extended to the yet unknown quadruple-layered systems 2 which consist of two quinhydrone moieties.

A method is suggested to calculate the geometrical and thermodynamical characteristics of organic π- complexes. The interaction energy is considered as a sum of two terms: the specific quantum chemical interaction of the π- electron systems depending essentially on the chemical nature of reactants, and the nonspecific atom-atom (van-der-Waals) interaction depending only on the kind of atoms belonging to the fragments of a complex. An attractive quantum chemical interaction is described in terms of the PPP-method; the van-der-Waals interaction is expressed in terms of the empirical exp-6-potential. The geometries of complexes are found by the complete energy minimization with respect to six parameters characterizing the mutual orientation of the complex fragments. Energies, entropies and equilibrium constants of several tetracyanoethylene π-complexes are calculated by this method. The results agree satisfactorily with experimental data.

The calculation of the echo envelope shape In powders containing nuclei with I= 3 2 was carried out for an arbitrary mutual orientation of the external fields and for any values of η. As a result of computer processing of the expression obtained for the situation in which the radiofrequency field is aligned parallel to the static magnetic field the relations between η and experimentally measured parameters were obtained. These relationships make possible the determination Value of η for nuclei with I= 3 2 in powders.

Under the influence of electron impact, esters of saturated keto acids of the indole series undergo the fragmentation typical for 3-acylindoles, whereas esters of unsaturated and aromatic 3-indolyl keto acids have specific mass spectra that reflect the peculiarities of their structure and the mutual orientation of the substituents.

The mutual orientation of substrates (molybdenum, tungsten) and the sulfide layer formed on the surface was investigated in [i]. Independently of the substrate orientation, the orientation of the sulfide layer was characterized by the fact that plane (001) of the sulfide is primarily parallel to the surface of the substrate. Some directions in the substrate and the sulfide layer are also parallel, i.e., the preferred orientation in the sulfide layer is limited.

1. The nature and mutual arrangement of the ring substitutents are the principal factors affecting the choice of fragmentation pattern in the breakdown of the trialkylcyclopentanes. 2. Quantitative differences in the spectra of structural isomers and stereoisomers can be used for purposes of identification. 3. The possibility that the fragmenting ion retain the mutual orientation of the substituents found in the parent molecule is discussed.

The reaction of 2-formylthiophenes with Meldrum's acid gave the corresponding thenylidenedioxanediones, which, in contrast to the furfurylidene derivatives, have an s-trans conformation of the mutual orientation of the thiophene ring and the exocyclic double bond. Thenyldioxanediones were synthesized by the selective hydrogenation of the exocyclic double bond.

The problem of orientation parameter refinement was considered in [8] for an orthogonal trihedron connected to an absolutely rigid body, and calibration of a device for measuring the angular velocity of the trihedron using information on the angular position of another connected trihedron was considered, where the mutual orientation of both trihedrons was unknown. A similar problem is solved below with an account of the possibility of elastic oscillation of the carrier body, whichchanges the mutual orientation of the coupled trihedrons.

In Langmuir-Blodgett films containing organic dyes, efficient energy transfer over distances exceeding 100 nm is observed. This exceptionally long-range transfer is interpreted as due to special mutual orientation of the dye molecules.

The degree of affinity of steroids of the estrone series for the estradiol-binding system of the guinea pig uterus was analyzed. The factor determining interaction with the receptor system of the guinea pig uterus was found to be the presence of free hydroxyl groups in positions 3 (phenol) and 17β and their mutual orientation. The results suggest that the biological activity of steroids is determined by the character of their structural interaction with the receptor systems of the uterus.

1. The constructive parameters of stream cooling devices are the diameter of the nozzle, the mutual orientation of the nozzle and the surface and the height of the nozzle above the surface, and the characteristics of the water supply system, which substantially affect the cooling rate and the hardness. These parameters must be selected in planning the cooling conditions. 2. Increasing the cooling rate by increasing the water pressure is not always effective; the water pressure should be selected on the basis of experiments with specific apparatus. 3. To ensure even hardening of the surface of flat parts it is necessary that the hardened zones from neighboring streams overlap.

Tridimensional associations of lamellar polymer single crystals, grown from dilute solutions, are described as derived from their sedimentation patterns. These associations include interlocked crystals and decorating crystal halves. The origin of these crystals and their mutual orientation are discussed and tentatively interpreted by specific interactions between the fold surface and the crystallizing chains.

Stress-induced changes in energy of the phonons of the lowest acoustic phonon branch in the (q00) direction are investigated in Si by using inelastic neutron scattering. Applying uniaxial stress of 10 kbar causes energy changes in the order of 1%. A change in sign is found approximately in the middle of the Brillouin zone. Depending on the mutual orientation of the stress, the wave vector and the polarization vector of the phonons, different changes in energy are observed. From the observed energy changes general mode Gruneisen parameters are derived. Frequenzanderugen des niedrigst liegenden transversal akustischen Phononenzweiges in (q00) Richtung in Si werden bei Anlegen von uniaxialer Spannung beobachtet. Als Mesmethode dient die inelastische Neutronenstreuung. Bei Spannungen von 10 kbar sind die relativen Frequenzanderungen im Bereich von 1%. Sie wechseln ihr Vorzeichen etwa in der Mitte der Brillouin-Zone. Bei gleichem q ergeben sich je nach Orientierung der Spannungsrichtung, des Wellenvektors und des Polarisationsvektors des Phonons unterschiedliche Frequenzanderungen. Aus den Mesergebnissen werden allgemeine Gruneisenparameter berechnet.

1. In carbon tetrachloride the molecules of 1,1-diphenyl-1,2-dichloro- and 1,1-diphenyl-1, 2-dibromoethanes coexist in the form of a mixture of rotational isomers with two-thirds of the form having the trans arrangement of the C-Hal bonds. 2. In both compounds one of the phenyl rings eclipses the ethane C-C bond, irrespective of the nature of the halogen and the mutual orientation of the C-Hal bonds; the second ring in the trans isomer is orthogonal to it, while in the gauche isomer it is close to eclipsing the geminal C-Hal bond.

Differences in the thermal stability of trapped lattice dislocations in interphase boundaries and grain boundaries in austenitic–ferritic steel have been studied. It was found that the distribution of diffusional properties of α/γ interphase boundaries depends on the mutual orientation of phases and differs significantly from the distribution of diffusional properties of α/α and γ/γ grain boundaries, which stems from the fact that interphase boundaries include a substantial fraction of boundaries of particularly low diffusivity. These are interfaces of austenite grains which nucleated inside ferritic grains and demonstrate Kurdjumov–Sachs or Nishiyama–Wassermann relationship with respect to the ferritic matrix.MST/1005

We present a calculation taking into account explicitly the size of the side groups used to improve the solubility of conjugated polymers. The results indicate a large change on the statistical lengths depending on the size and mutual orientation of the side groups. On the other hand, this calculation provides a possible explanation on the absence of the temperature dependence of the statistical length (1/T law) for some polydiacetylenes.

The crystal structure of the title compound has been determined by X-ray methods. The geometry of the complex anion is a slightly distorted octahedron, and the coordinated four nitro groups occupy the cis -positions. The mutual orientation of these nitro groups is considered to be effected mainly by the intramolecular nonbonded repulsions.

It is shown that the principal topotaxial relationship between hematite α-Fe2O3 and magnetite Fe3O4 during cycles of reduction and oxidation can be considered as crystallographically reversible. The precision of the mutual orientation of the two lattices decreases as the number of cycles of reduction and oxidation increases and there is a correlation between crystallographic orientation and the rate of oxidation and of reduction.

On the basis of the measurements of dipole moments and Kerr constants it can be said that the oxides of the thiophene chalcone analogues exist in s-cis and s-trans conformations, these differing in the mutual orientation of oxirane ring and carbonyl group.

The first experimental study of two mesophases mutual orientation is done with three smectics B1 and three nematics. The smectics B orient the nematics. The axes of the molecules are parallel in the two mesophases.

Two in situ measurements of stress wave velocity in a granodiorite massif were made. Firstly, the velocities close to the source were investigated (for elimination of the influence of cracks), and secondly, the velocities in different horizontal directions over a large area were studied from the viewpoint of their dependence on the crack system of the medium. A correlation between the mutual orientation of the cracks and the maximum or minimum values of the stress wave velocities was obtained.

This essay reappraises conventional distinctions between oral-like and literate-like discourse, particularly Tannen's (1985) distinction between involvement focus and message focus. Rather than seeing message in tension with involvement, this query treats message as an embodiment of involvement. Cohesion particularly is treated as an aspect of a developing writer-reader relationship, an outgrowth of a thickening commitment to a mutual orientation. Speculations are offered for rethinking what is called “literate orientation.”

Bott a defini le reseau social comme etant un ensemble de relations sociales qui ne possedent pas de frontieres communes. Par ailleurs personne ne s'est preoccupee d'explorer les reepercussions qu'engendrent cette connexion entre ces deux concepts. En se basant sur la definition Weberienne d'une relation sociale ou interper-sonnelle (m), il devient evident qu'essentiellement c'est une orientation mutuelle entre deux individus; c'est une perception subjective ou une predisposition. Les consequences logiques de cette observation par rapport au reseau social sont examinees. On arrive a la conclusion que les reseaux sont aussi des modeles sub-jectifs et, par voie de consequence, ils possedent le pouvoir de guider la conduite dans une situation sociale. Bott has defined social network as a set of social relationships for which there is no common boundary. Yet, no one has ever bothered to explore the implications of this connection between these two concepts. By examining Weber's definition of social or interpersonal relationship (ir), it becomes evident that it is basically a “mutual orientation” between two persons; it is a subjective construct or predisposition. The logical consequences of this observation for the social network are considered, and it is concluded that networks are also subjective constructs and therefore have the potential to guide behaviour in the social situation.

The polymorphism of social wasps has been studied by arranging the different structural types in a generalised distance chart. These structural types group the wasps according to their sex, caste and species. Between each of a pair of types is the appropriate generalised distance, that is, the vector separation afforded by seven morphometric characters, combined into a discriminant function. The mutual orientation of these generalised distances reflects the various underlying modes of growth elicited during the larval instars, when all the distances are put together in a chart.

Intramolecular triplet-triplet energy transfer between nonconjugated molecular chromophores held together by rigid molecular frame at known separation distance and mutual orientation

1. Some adducts of fumaronitrile and maleonitrile with cyclic dienes were synthesized. 2. The dipole moments of 14 compounds were measured; the endo-structure was determined on the basis of them for the adduct of cyclopentadiene, furan, hexachlorocyclopentadiene, and tetracyclone with maleonitrile. 3. The dipole moments of the bonds in 1,2-disubstituted structures are strongly dependent upon the mutual orientation.

The paper presents the study of colours due to the combination of two identical or two different dichroic filters put in natural light and of colours obtained with a single filter or the combination of two filters put in linearly polarized light if their mutual orientation or their orientation with respect to linearly polarized light is changed. It is shown that in the colour diagram the colours lie on straight lines and that generally they occupy a quadrangular region. On the basis of mathematical relations derived it was shown that the colours fulfil the additive law of colour mixing and that they may be approximately expressed by means of addition of four colours properly defined.

(1) By comparison of the data on the photochemical decomposition and the azomethane‐induced decomposition of acetaldehyde vapor, it has been concluded that the chain‐carrying steps in the two cases are different. For the photolysis the following mechanism is suggested: (1)CH3CHO+hν→CH3+CHO, (2)CHO+CH3CHO→CH4+CO+CHO, (3)CHO+CH3→stable products (chain−ending),(4)CHO→stable products (chain−ending). (There are possibly other chain‐ending steps similar to reaction (3)). (2) Experiments have been performed using intermittent light at 200° and 300°. As a result of these experiments, estimates have been made for the individual rate constants, k2, k3, and k4, and it has been found that the activation energies are 2.6, 11.3, and 7.8 kcal., respectively. (3) It has been found that k2 and k3 check closely with the collision number multiplied by the appropriate Arrhenius factor. There is little or no evidence of necessity for mutual orientation of the molecules. The significance of this has ...

A system for designation of various types of mutual orientation of crystals and the processes during which they are formed is proposed. The neutral terms oriented overgrowth, oriented intergrowth and oriented inclusions, and in special cases polycrystal and single-crystal films, are considered to be sufficient for describing the fact of regular joint growth. As interpretative and genetic, four basic terms are submitted: epitaxy – for oriented growth of a phase on the crystal surface of another phase; syntaxy – for simultaneous growth of the mutually oriented crystals of two or more phases; topotaxy – for oriented transformation in an open system with a partial alteration in chemical composition of the primary crystal; and endotaxy – for oriented transformation in a closed system, without exchange of components between the system (primary crystal) and its environment. For a later oriented overgrowth of crystals of one and the same phase (in parallel or twin position) it is possible to use the term autoepitaxy.