Symmetry breaking structural phase transitions, dielectric properties and molecular motions of formamidinium cations in 1D and 2D hybrid compounds: (NH2CHNH2)3[Bi2Cl9] and (NH2CHNH2)3[Bi2Br9].

Two organic-inorganic hybrid halobismuthates(iii), (NH2CHNH2)3[Bi2Cl9] (FBC) and (NH2CHNH2)3[Bi2Br9] (FBB), have been prepared with their structures revealed by single-crystal X-ray diffraction at various temperatures. FBC is characterized by one-dimensional (1D) [Bi2Cl9]3-∞ anionic chains built by edge-sharing BiCl6 octahedra, whereas FBB adopts a layer structure (2D) [Bi2Br9]3-∞. Both materials were found to exhibit a rich polymorphism in the solid state. FBC undergoes two reversible phase transitions (PTs) at 218/220 K and at 123/126 K (cooling/heating), respectively, whereas for FBB also two PTs occur close together at 196/199 K and at 190/188 K. Dielectric response around the PT temperatures of FBC and FBB reflects high disorder of dipolar groups over the high temperature phases. The 'order-disorder' mechanism of these PTs is assigned to the dynamics of formamidinium cations. FBB is considered as a ferroic material exhibiting ferroelastic domains below 196 K. The molecular motions of organic cations in a wide temperature range were studied by means of 1H NMR (spin-lattice relaxation time). Presented findings will provide a new method to explore organic-inorganic multifunctional PT materials.

Widely used hardly known. An insight into electric and dynamic properties of formamidinium iodide.

The simple organic crystal formamidinium iodide (FAI) appeared to be a novel semiconducting material in a wide temperature range. The electric properties of FAI and the role of formamidinium cation (FA+) in the molecular mechanism of the solid-to-solid phase transitions (at 345 K (III → II) and 388 K (II → I)) were analysed. The creation of the ferroelastic domain structure in phases III and II was proved on the basis of observation under a polarizing microscope. Moreover, the molecular arrangement of dipolar organic FA+ was studied by 1H NMR (spin-lattice relaxation time) and vibrational spectroscopy supported by density functional theory. The theoretical results show a good agreement with the experimental data. The infrared spectrum in a harmonic approximation was calculated and a comparative vibrational analysis was performed. All used techniques showed that the prototypic phase I exhibits the feature of plastic phase.

Relationships between ovarian cysts and morphological and hormonal state of ovarian cortex in sows.

The aim of this study was to evaluate the relationship between ovarian cysts and concentrations of ovarian steroid hormones: 17beta-estradiol (E(2)), progesterone (P(4)), testosterone (T), and androstendione (A(4)) both in blood plasma and in cysts and morphological state of the ovarian cortex in sows. Females were divided into three groups: PCO (sows with polycystical ovaries), OO (sows with oligocystic ovaries) and control (sows without ovarian cysts). The ovaries for evaluations were collected after slaughtering of 18 multiparous sows. Between the PCO and OO animals, statistically significant differences in numbers of the follicular cysts (FC) (8.6 vs. 1.5), follicular theca-lutein cysts (FTLC) (8.0 vs. 2.0), follicular lutein cysts (FLC) (4.5 vs. 2.0) and corpus luteum cysts (CLC) (1.7 vs. 0.4) (P< or =0.01) were noted. In the PCO sows the most common kinds of cysts were FC and FTLC (8.6 and 8.0) whilst in OO sows the cysts occurred on their ovaries on a similar level (FC - 1.6, FTLC - 2.0, FLC - 2.0). Existence of more than 10 ovarian cysts in the sows significantly decreases the frequency of physiological ovarian follicles (primary, growing and maturing) and significantly increases the pathological process of atresia on all stages of ovarian follicles development (P< or =0.01). The study did not reveal any effect of growing or decreasing number of ovarian cyst on concentrations of E(2) and P(4) in blood plasma of sows. Polycystical ovaries significantly decreased concentrations of A(4) but increased the concentration of T in blood plasma (P< or =0.01). The general presence of ovarian cysts considerably positively correlated with concentrations of E(2), T and A(4) from cysts' fluid, of all kinds of ovarian cysts and atresia of primary follicles (a correlation coefficient r from 0.72 up to 0.97, P< or =0.05). The phenomenon of ovarian cysts significantly negatively correlated with all generations of ovarian follicles (P< or =0.05).