Kinetics of formation of polymer dispersed liquid crystals in a liquid-crystalline polymer matrix

With the use of optical polarization microscopy, the kinetics of phase separation during cooling of molten mixtures of a nematic low-molecular-mass liquid crystal and a liquid crystalline polymer is studied to produce polymer dispersed liquid crystals. The statistical drop-size distribution of a low-molecular-mass liquid crystal is described in the terms of equilibrium thermodynamics of irreversible processes. For a nematic polymer component of a mixture, the analysis of time dependences of the average diameter of drops of a low-molecular-mass liquid crystal makes it possible to reveal two stages in the kinetics of their growth and to describe this process according to the universal law of cluster growth. For a smectic polymer component, the Avrami equation is used to quantitatively describe the kinetics of growth of low-molecular-mass liquid-crystal drops.     

漫谈有效数字和计算器

介绍了有效数字的概念及其计算规则,介绍了计算器的一般特性及使用技巧,并给出计算实例.     

速度算符和电子的颤动

指出了国外某些量子力学教材中关于速度算符的概念错误和相对论自由电子进行颤动的错误,分析了错误的原因.     

A new approach to the description of the deformation kinetics and relaxation of mechanical properties of oriented polymers

The reduction of Young's modulus and stress as well as the creep rate of highly oriented polymers with different chemical structure has been investigated. The kinetics of these processes are described by Arrhenius-type equations having the same activation parameters. The deformation and relaxation processes were assumed identical in their physical nature and functions of thermal fluctuation. Evidence for this assumption was obtained by investigating spectroscopically excited extended interatomic bonds of the macromolecules. The generation of excited bonds was found to determine the kinetics of these macroscopic processes in polymers.     

Solitonlike solutions for interacting fields with consideration of gravitation

Within the general theory of relativity the interaction between scalar and vector massless fields with interaction LagrangianF ^αβ F _αβ Ψ (?) is considered, where ψ is an arbitrary function of the scalar field. For six types of space-time symmetry (spherical, cylindrical, pseudospherical, planar, pseudoplanar, and toroidal) such interaction induces nonlinearity in the scalar field, which can be chosen in trigonometric (for example, sin-Gordon) or polynomial form. Exact solutions of the field equations are obtained for all six symmetries. The spherically symmetric solutions are studied in detail and solitionlike solutions are found.     

Thermophysical properties of macromolecules in the block state

The macromolecules of linear polymers usually consist of regular helices. The paper presents the results of investigation of the concentration, thermal expansion coefficient and vibration amplitude of such helices at different temperatures. These parameters were determined from temperature dependences of the intensity, frequency and halfwidth of regular bands in IR and Raman spectra of polymers.

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Zusammenfassung Die Makromoleküle linearer Polymere zeigen gewöhnlich Helixstruktur. Es wurden Konzentration, Wärmeausdehnungskoeffizient und Schwingungsamplitude derartiger Helizes bei verschiedenen Temperaturen untersucht. Diese Parameter wurden anhand von Intensität, Frequenz und Halbwertbreite der Normalbanden in IR- und Raman-Spektren von Polymeren bestimmt.

     

The kinetics of cholesteric phase growth from an isotropic melt of liquid crystalline polymer with mesogenic groups in the main chain

The kinetics of growth of cholesteric phase drops in the phase transition (during cooling) of an isotropic melt of a liquid crystalline polymer containing mesogenic groups in the main chain was studied by polarization optical microscopy. The statistical drop size distribution was described in terms of the equilibrium thermodynamics of irreversible processes. An analysis of the time dependences of the mean diameter of drops revealed the existence of two stationary stages of the kinetics of cholesteric phase growth and allowed these stages to be quantitatively described by the universal law of the growth of clusters.     

Self-Gravitating String-Like Configurations of Nonlinear Spinor Fields

We consider the problem of the existence of soliton-like self-gravitating cylindrically symmetric configurations of a classical spinor field with the nonlinearity F(S) ( , F is an arbitrary function). Soliton-like configurations should have, by definition, a regular axis of symmetry and a flat or string-like geometry far from the axis (i.e., an asymptotically Minkowskian metric with a possible angular defect). It is shown that these conditions can be fulfilled if F(S) is finite as S and decreases faster than S ² as S 0. The set of field equations is entirely integrated, and some explicit examples are considered. A regularizing role of gravity is discussed.     

A multidimensional global monopole and nonsingular cosmology

We consider a spherically symmetric global monopole in general relativity in (D=d+2)-dimensional space-time. For γ<d?1, where γ is a parameter characterizing the gravitational field strength, the monopole is shown to be asymptotically flat up to a solid angle defect. In the range d?1< γ<2d(d+1)/(d+2), the monopole space-time contains a cosmological horizon. Outside the horizon, the metric corresponds to a cosmological model of the Kantowski-Sachs type, where spatial sections have the topology ? × S ^d . In the important case where the horizon is far from the monopole core, the temporal evolution of the Kantowski-Sachs metric is described analytically. The Kantowski-Sachs space-time contains a subspace with a (d+1)-dimensional Friedmann-Robertson-Walker metric, whose possible cosmological application is discussed. Some estimates in the d=3 case show that this class of nonsingular cosmologies can be viable. In particular, the symmetry-breaking potential at late times can give rise to both dark matter and dark energy. Other results, generalizing those known in 4-dimensional space-time, are derived, in particular, the existence of a large class of singular solutions with multiple zeros of the Higgs field magnitude.