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The hysteresis and kinetics of the electro-optic response of multilayer ferroelectric polymer Langmuir–Blodgett films have been investigated.

The orientation of the lamellar phases in lyotropic systems based on cetyltrimethylammonium bromide (CTAB) detergent has been studied by polarization optical microscopy and 2H-NMR methods. The lamellar lyotropics studied are shown to align under a strong magnetic field of 11.7 T. According to 2H-NMR data, structural transformations of the lamellar phases may occur during orientation when the sample temperature increases.

The internal bias field distribution in large crystals of deuterated triglycine sulphate with an L-alanine impurity (LADTGS) grown on elongated seeds is shown to be inhomogeneous, polar symmetric, and dependent on (010) growth pyramid twinning in the (110)-pyramid zone.

In this paper we report the experimental data on the visualisation of die domain structure by FLCs in two different crystals: ammonium lithium sulphate (ALS) and deuterated triglycine sulphate (DTGS). In general, for ferroelectric solid crystals (FSC) two different geometries are available for the decoration: polar and nonpolar cuts, i.e. slices normal or parallel to the polar axis. In the experiments with FLC materials we used only polar cuts, i.e. FLC on the polar (010) plane of ALS and DTGS. The samples were prepared as sandwich structures FSC-FLC-electrode-glass substrate. The dynamic switching of the FSC domain-structure is discussed. The generation of a pyroelectric domain structure is also demonstrated.

An extended inversion boundary separating two large 180°; domains of a flux-grown KTP crystal is studied by nematic liquid-crystal (NLC) surface decoration and by X-ray projection and section topography using Mo- K α radiation. Although a non-polar (100) cleavage plate was used for NLC decoration, the domains appeared by bright optical contrast. The boundary exhibits a mainly irregular zigzag course with an—on average—charged orientation and is clearly visualized by both methods. It appears by strong contrast in X-ray reflection 004 (normal to the polar axis) and is completely invisible in reflection 040. A large uncharged planar boundary segment parallel to the polar axis and inclined by ca . 40° to the normal of the specimen surface shows in reflection 004 dynamical fringe contrast of the stacking fault type. A section topograph of this segment exhibits an ideal 9hour–glass9 contrast pattern, proving the absence of long-range strain and of any tilt of the reflecting (001) planes across the inversion boundary.

It is found that static domain structure in different growth pyramids and crystal cuts of flux-grown KTiOPO4 ferroelectric crystals can be visualized with high resolution and studied in detail by nematic liquid crystal method. The domain structure decorates the peculiarities of the crystal growth and corresponds, in the main, to the layers of growth. Head-to-head and tail-to-tail domain walls exist due to high ionic conductivity of the crystal in the region, of domain formation.

Results of investigations of domain structure and mechanical properties of DMAAS crystals over a wide temperature range are reported. Dielectric properties under external mechanical copression stress are studied. Structural changes upon twinning and gliding are found.

Optical measurement and microscopic observations have been performed of single crystals of (TMA)2ZnCl4 with the aim to establish its phase diagram in the coordinates temperature-uniaxial stress σ. Stress-induced shifts of transition temperatures have been evaluated. For stresses exceeding 4.5 MPa two new monoclinic phases are reported, tentatively labeled as VIII and IX, both with the monoclinic axis b.

An attempt is made to extend the method of experimental analysis of fluctuation behaviour at normal (N)—incommensurate (INC) phase transitions in the case of narrow INC-phases. Values of fluctuation parameters (the “effective Ginzburg Numbers”) for RbH3(SeO3)2 and RbD3(SeO3)2 crystals are suggested and compared with those of some other crystals from the A2BX4 family (G = 0.01 ÷ 0.036). In addition, in the crossover region the role of defects is clearly demonstrated by comparing the behaviour of incompletely deuterated crystal Rb(H, D)3(SeO3)2 with that of RbH3(SeO3)2.

Single crystals of [N(CH3)4]2FeCl4 have been prepared from water solution. For platelets perpendicular to the three orthorhombic axes of the high-temperature phase Pnma we present data on the temperature dependence of birefringence, orientation of the indicatrix, permittivity and domain structure. On the basis of these results and of previous studies we suggest the following phase sequence to take place on decreasing temperature: Phase I Pnma—modulated phase II with k i along the a-axis—phase III' presumably monoclinic with k = (3/7)a∗—lock-in phase IV P21/n11—lock-in phase PT. This differs from the previously published phase diagram in the absence of a reentrant incommensurate phase, in the presence of a monoclinic phase before the lock-in monoclinic P21/n11 is reached, and in the fact that the last phase is triclinic.

Anomalous (non-classical) temperature behaviour of birefringence at the second-order normal-incommensurate phase transition in Rb2ZnBr4 crystals is studied experimentally. An attempt is undertaken to discuss it using the existing theoretical approach. A critical review of some theoretical results concerning the temperature dependence of the local mean square of an order parameter is given both for the region of small corrections to the results of the Landau theory and for the scaling region. It is shown that, in the region of 'small corrections' (at mod tau mod approximately=10-1), qualitative agreement of the experiment with the results of fluctuation theory can be recognised. Near the critical point, at mod tau mod

The measurements of birefringence and indicatrix rotation of betaine calcium chloride dihydrate (BCCD) in the temperature region 90-220 K are reported. A weak indicatrix rotation observed below 164 K is probably connected with an additional phase transition at the temperature of about 0.3 K below Ti.

The reactogenic properties and immunological potency of modified cholera chemical vaccine (choleragen-toxoid + O-antigens Inaba and Ogawa) were tested in 278 volunteers aged 18 years and over in comparison with those of a commercial batch of monovalent cholera vaccine (choleragen-toxoid + O-antigen Inaba). The cholera vaccine, enriched with O-antigen Ogawa, was found to be safe; vaccination with this vaccine was not accompanied by the development of systemic and local reactions whose frequency and intensity met the requirements for the reactogenic properties of commercial cholera vaccine. The immunological potency of the bivalent vaccine with respect to strain Inaba was not inferior to that of the commercial vaccine; at the same time in persons immunized with the new preparation the titers of vibriocidal antibodies to strain of serovar Inaba were five-fold higher. The conclusion on the expediency of using cholera chemical vaccine enriched with O-antigen Ogawa was made.

276 volunteers aged 19 years and over were placed under observation in the course of the trial of oral cholera vaccine in tablets, containing choleragen toxoid, O-antigens of serovars Inaba and Ogawa and a number of Vibrio cholerae exoenzymes, for safety, reactogenic properties and immunological effectiveness. The vaccine was found to produce no reactions in a dose of 1-4 tablets; the administration of 3 tablets (300,000 binding units of the toxoid and 10,000 units of O-antigens, serovars Inaba and Ogawa) was shown to induce the most intensive synthesis of both antitoxins and vibriocidal antibodies in the blood sera of volunteers, as well as IgA coproantibodies. The oral vaccine was found to have an advantage over parenteral vaccines due to the absence of reactogenic properties and the formation of local immunity: coproantibodies appeared in 80% and 9% of the vaccinees respectively.

The 90°-light scattering on domain walls was probed in various strontium barium niobate (SBN) crystals for studies of the ferroelectric switching under pulsed fields. The validity of this optical method is proved by a good agreement of the switching parameters deduced from optical scattering data with those obtained with electric methods. Scanning of the scattering over the crystal bulk revealed local specialities of the switching, particularly, a marked distribution of the domain wall density D along the polar axis with a maximum close to the negative electrode. In compliance with these in situ observations, the electro-optic coefficient rc reveals a position dependence in all SBN crystals poled in the ferroelectric phase, rc decreasing from the positive to negative electrode. This regularity is interpreted in terms of the domain density distribution D(z) and accounted for by an asymmetry of the domain nucleation.

The electro-optical coefficients r ij and half-wave voltage V λ /2 of strontium-barium niobate crystals poled in the ferroelectric phase are shown to vary along the polar axis. The r ij ( z ) and V λ /2 ( z ) dependences indi- cate the presence of a residual domain density D ( z ) and clearly depend on the sign of the polarizing field, with r ij being minimum ( D being maximum) near the negative electrode. This character of the D ( z ) distribution and, hence, the r ij ( z ) and V λ /2 ( z ) coordinate dependences can be explained by predominant domain nucleation near the negative electrode, which is revealed when the switching processes are studied using 90 ° (Rayleigh) light scattering from domain walls. © 2005 Pleiades Publishing, Inc.

Temperature dependences of birefringence and optical activity in KLiSO4 are studied and used for analysis of symmetries of the phases in temperature region 150-300 K. Monoclinic (class 2) and triclinic (class 1) symmetries were found for phases IV and V. Kinetics of the phase transitions is discussed

The salicylate content in blood plasma after its administration into the stomach and small intestine during experimental endotoxemia in mice has been measured. In early stages of intoxication gastric evacuation was fairly slow. Histamine increased, while its antagonist pyrilamine significantly reduced the observed disorder. In the last stages of intoxication, passive absorption in the small intestine increased. Administration of histamine, serotonin and ciproheptadine did not produce any essential effect on the salicylate transport across the intestinal wall.

The temperature dependence of some elastic compliance and stiffness coefficients, linear thermal expansion coefficients, and coefficients of electrostriction from tris-sarcosine calcium chloride (TSCC) are presented. The results are discussed using a simple thermodynamical model. Obviously at the transition deformations take place only in the (001)-plane. Die Temperaturabhangigkeiten einiger elastischer Nachgiebigkeiten, elastischer Steifigkeiten, linearer thermischer Ausdehnungskoeffizienten und Elektrostriktionskoeffizienten von Tris-Sarcosin-Calcium-Chlorid (TSCC) werden vorgestellt. Die Ergebnisse werden anhand eines einfachen thermodynamischen Modells diskutiert. Offenbar treten bei der Phasenumwandlung Verzerrungen nur in der (001)-Ebene auf.

Mise en evidence de variations discontinues des coefficients de dilatation aux temperatures de transition de phase (350 K, 190 K et 113 K)

Dielectric and optical measurements of monoclinic RbD2PO4 in the temperature region around its phase transitions at T c1 = 372 K and T c2 = 320 K are reported. The nonclassical behaviours of the dielectric and optical properties were observed at both phase transitions. The effect of the biasing electric field on phase transitions and the relaxational dielectric dynamics have been investigated.

In earlier investigations on the field dependence of the orientation of the indicatrix of TGS during polarization reversal anomalous electrooptic signals are observed. It is shown that these anomalies are due to relaxation processes which can be described by two time constants. As the change of the indices of refraction, as well as piezoelectric strains and polarization, do not exhibit such anomalies, it is assumed that inhomogeneities of the crystal are the reason for these phenomena. It is shown that the observed anomalies can be described by a surface layer where, due to space-charge fields, the orientation of the indicatrix differs from that within the bulk of the crystal. Bei fruheren Untersuchungen uber die Feldstarkeabhangigkeit der Drehung der Indikatrix des TGS werden wahrend des Umpolens anomale elektrooptische Signale beobachtet. Es wird nachgewiesen, das diese auf Relaxationsprozesse zuruckzufuhren sind, die sich mit zwei Zeitkonstanten beschreiben lassen. Da die Anderung der Brechungsindices ebenso wie die piezoelektrischen Dehnungen und die Polarisation keine derartigen Anomalien aufweisen, ist anzunehmen, das die oben genannten Erscheinungen durch Inhomogenitaten des Kristalls hervorgerufen werden. Es last sich zeigen, das die beobachtete Anomalie durch eine Randschicht beschrieben werden kann, in der sich auf Grund von Raumladungsfeldern die Orientierung der Indikatrix von der im Innern des Kristalls unterscheidet.

The phase transition in phenanthrene C14H10 crystals at 72°C has been investigated. The measurements of dielectric, pyroelectric, optical and acoustical properties were performed and are reported here. The preliminary refinement of the x-ray data shows that the high temperature phase is orientationally disordered. The results indicate that the transition is probably pseudoproper ferroelectric with a symmetry change 2/m - 2.

The occurrence of a shock-like state in connection with an infectious disease was first reported by Laennek in 1831. More specifically, this relationship was established in 1899 [46]. The absence of a noticeable decrease in the frequency of recorded endotoxin shock in humans is due to a number of factors, the most important among which are the following: a) improvement in the diagnosis of endotoxin shock, made possible by the use of sophisticated diagnostic equipment; b) familiarity of specialists of various profiles with this nosological form; c) an increase in the life expectancy of patients with severe pathology and a decrease in general and immunological reactivity; d) the use of immunosuppressants and cytostatic drugs for allergies, malignant neoplasms, which facilitates the development of infectious pathology; e) frequent obstetric pathology, accompanied by the birth of children with reduced resistance; f) widespread use of antibiotic therapy, leading to the emergence of antibiotic-resistant microbes; it should also be noted here that when treating septic foci and infectious diseases with antibiotics, there is a danger of massive entry into the bloodstream of endotoxins released from dead microorganisms; g) carrying out complex diagnostic manipulations and surgical operations that open the entrance gates for infection.

The piezooptic behaviour of CsLiSO4 corresponds to the phenomenological model of a pseudoproper ferroelastic transition in a wide temperature region of the paraelastic phase but is violated in the vicinity of the phase transition. Log-log analysis of spontaneous values of birefringence, optical indicatrix rotation and shear strain indicates that the transition is very near (0.2°) the tricritical point.

Dielectric, optical and elastic properties of dimethylaminaluminiumsulphate crystals were studied. The crystal is shown to undergo a nearly tricritical second order phase transition with the symmetry change 2/m–m at Tc = 150 K. The transition can be classified as a proper ferroelectric one of the order-disorder type. Above the Tc the crystal exhibits ferroelastic behaviour.

The emergence of gram-negative septicemia in humans can be facilitated by a number of factors: 1) insufficiently effective treatment of foci of infection; 2) development of resistance of microorganisms to antibacterial agents; 3) decrease in the resistance of patients, including as a result of chronic debilitating diseases; 4) long-term therapy with corticosteroids, immunosuppressants and cytostatic drugs. The most essential link in the pathogenesis of septicemia is the effect on the body of bacterial endotoxins.

Dielectric and pyroelectric behaviour of phenanthrene single crystals between 20 and 90°C have been investigated. Sharp peaks of e have been observed during first heating of the samples. The pyroelectric charge in b-direction has been detected without a biasing field. The most probable explanation of all data available seems to be a phase transition without change of symmetry.

The statistical theory, taking into account the short-range correlations between the ordering ions and between the latter and phonons, is proposed for the phase transitions in pure ferroelastics. The thermodynamic characteristics of the transition are expressed through the microscopic parameters. The connection between the elastic and dielectric properties is revealed. Ferroelastic properties of KH3(SeO3)2 and KD3(SeO3)2 crystals are calculated and the qualitative agreement with the experiment is obtained. The comparison of microscopic and phenomenologic theories describing the thermodynamic properties of pure ferroelastics is presented.

The temperature dependence of the electrostriction coefficient Q near the paraelectric–ferroelectric phase transition in tris-sarcosine-calcium chloride (TSCC) is reported. This temperature dependence as well as earlier results may be described by a potential including a linear coupling between polarization and order parameter. Es wird uber die Temperaturabhangigkeit des Elektrostriktionskoeffizienten Q in der Nahe der paraelektrisch–ferroelektrischen Phasenumwandlung in Tris-Sarcosine-Kalziumchlorid (TSCC) berichtet. Diese Temperaturabhangigkeit kann ebenso wie fruhere Ergebnisse mit Hilfe eines Potentials beschrieben werden, das eine lineare Kopplung zwischen Polarisation und Ordnungs-parameter enthalt.

An anomalies of birefringence and thermooptic coefficient at the second order normal-incommensurate phase transition in Rb2ZnBr4 are investigated and discussed using fluctuation and defect theories.

Experimental data are presented for the temperature dependences of the spontaneous birefringence and orientation of the indicatrix in the ordered phase of CAS and of their field-induced changes. These quantities are expressed in terms of ΔB6s = Δ(σE1/σD2)spont. and of the electrooptical coefficient r63 = σB6/σP3, related to the paraelectric coordinate system. Phenomenological theory explaining the birefringent and electrooptical properties of CAS is developed; since its phase transition is improper ferroelectric, coupling of ΔB6 to both polarization and order parameters is taken into account. It is shown that the electrooptic contribution accounts for only 11% of the ΔB6s value. Optical properties of CAS are found to differ considerably from those of another improper ferroelectric, Gd2 (MoO4)3.

An investigation is made of the spontaneous polarisation, the coercive field, the dielectric constant, the electro-optical behaviour, and the domain structure of ferroelectric NaH3(SeO3)2 single crystals in the temperature range −195 to 0 °C. The existence of two phase transitions and two ferroelectric phases is confirmed; the presence of two domain systems and a contribution of this domains to the dielectric constant in the triclinic ferroelectric phase is observed. The multiaxial electrical behaviour of the crystals in this phase, the enantiomorphism of the domains, and other peculiarities of electrical twinning are discussed. A large difference is noted in the behaviour of the mutually orthogonal components of the spontaneous polarization.

It is shown that Na(DxH1-x)3(SeO3)2 crystals are isotopically nonisomorphous. It is found that external electric field Ey significantly widens temperature and concentration regions of existence of γ-component of spontaneous polarization ; hydrostatic pressure widens concentration region of existence of Psy and induces a new phase whose properties depend on field Ey.

Dielectric constant, rotation of optical indicatrix and birefringence of KH3(SeO3)2 and KD3(SeO3)2 crystals are investigated depending on temperature and mechanical stress in the region of proper ferroelastic phase transition mmm ← 2/m. Thermodynamic analysis of spontaneous and induced linear and quadratic piezo-optical and piezodielectric effects has been carried out. It is shown experimentally that a new electromechanical effect‐quadratic piezodielectric effect‐is the origin of dielectric anomalies. It is shown that the linear effects (piezo-optic and piezodielectric (electrostriction)) arise in ferroelastic phase due to linearization of corresponding quadratic effects of paraelastic phase.

Experimental data on the effect of electric fields and 7-radiation on phase transitions in Na(DxH1-X)3(SeO3)2 crystals are reported. A theoretical model which explains many of the peculiarities of these crystals is proposed.

The monoclynic form of RbD2PO4(DRDP) has two successive phase transitions: at TI-II=381 K and TII-III22 =311 K1. The superlattice structure occurs below TI-II (P21/m-P21/n)2. The typical antiferroelectric double hysteresis loops observing in the phase III is out of line with the polar group of symmetry of this phase (P21)2. The new phase IV is induced by the pressure higher than 0.7 GPa3.

The study of ferroelastic phase transitions1 is of interest as a part of general problems of structural phase transitions, and ferroelastic crystals are promising materials for acousto-optical and nonlinearacoustical applications. KH3(Se03)2 crystal undergoes the second-order phase transition at −62°C from phase mmm into a low-temperature phase having domain structure.2 This transition is pure (pseudo)proper ferroelastic one of order-disorder type, and low-temperature phase has point symmetry 2/m.3 First evidence of the isotopic effect of the transition was found in Ref. 4, and some time later another independent publication5 had appeared; it was shown that 80%H → D substitution rises transition temperature by 75°C,4 and 100% H → D-by 85°C.5 Order parameter η in KH3(Se03)2 is homogeneous, it couples linearly with shear deformation x 5 (matrix notation), therefore its temperature behaviour can be obtained from the rotation of axes of any symmetric polar 2nd rank tensor, e.g. from the rotation of o...

A comparison of the quadrupole perturbed deuteron magnetic resonance spectra of the α,β, and γ phase of partially deuterated sodium trihydrogen selenite crystals shows that not only in the monoclinic γ but also in the triclinic β phase the deutrons are ordered whereas they are disordered in the α phase. Spin-lattice relaxation time measurements show the existence of slow hindered rotations of the HSeO 3 and H 2 SeO 3 groups at high temperatures as well as the existence of an overdamped ferroelectric soft mode which condenses at the paraelectric to ferroelectric transition.

Oral cholera chemical vaccine in the doses tested (2 and 3 tablets) proved to be areactogenic, harmless and immunologically effective in a controlled limited trial in 150 volunteers. By the results of titration of specific antitoxins and vibriocidal antibodies in the blood serum, as well as of coproantibodies a dose of 2 tablets was chosen as the optimal one.