Relationship between Local Structure and Relaxor Behavior in Perovskite Oxides

Despite intensive investigations over the past five decades, the microscopic origins of the fascinating dielectric properties of ABO3 relaxor ferroelectrics are currently poorly understood. Here, we show that the frequency dispersion that is the hallmark of relaxor behavior is quantitatively related to the crystal chemical characteristics of the solid solution. Density functional theory is used in conjunction with experimental determination of cation arrangement to identify the 0 K structural motifs. These are then used to parametrize a simple phenomenological Landau theory that predicts the universal dependence of frequency dispersion on the solid solution cation arrangement and off-center cation displacements

Fatigue failure mechanisms of thin-walled hybrid plate girders

Steel plate girders of bridges and industrial structures are usually subjected to dynamic fatigue loading. Their thin-slender webs under dynamic fatigue loading are laterally buckling and vibrating. The consequence of that can be arising and successive development of fatigue cracks along the welded connections of the thin webs with flanges and stiffeners. Therefore, the fatigue strength and life/time of thin-walled plate girders depend beside of usual material-technological and structural influences also on stability aspects. Basic knowledge about fatigue failure mechanisms of thin-walled hybrid plate girders is presented with the regard for their local stability, obtained and by theoretical an experimental analyses. The outcome of obtained results is that the fatigue consequences of thin webs vibration can be effectively reduced by appropriate reduction of their slenderness. Therefore, the empirical formula for the limitation of web slenderness has been proposed and recommended for plate girders subjected to dynamic fatigue loading

Effects of a Combination of Thyme and Oregano Essential Oils on TNBS-Induced Colitis in Mice

We examined the anti-inflammatory effects of the combination of thyme and oregano essential oil dietary administered at three concentrations (0.4% thyme and 0.2% oregano oils; 0.2% thyme and 0.1% oregano oils; 0.1% thyme and 0.05% oregano oils) on mice with TNBS-induced colitis. Treatment of colitic animals with the essential oils decreased the mRNA levels of pro-inflammatory cytokines IL-1β, IL-6, GM-CSF, and TNFα, especially after application of the medium dose. The medium dose of the essential oils significantly lowered the amount of IL-1β and IL-6 proteins too. Moreover, administration of the medium dose decreased the mortality rate, accelerated the body weight gain recovery, and reduced the macroscopic damage of the colonic tissue. Our results indicate that combined treatment with appropriate concentrations of thyme and oregano essential oils can reduce the production of proinflammatory cytokines, and thereby attenuate TNBS-induced colitis in mice

Structural Changes during the Growth of Atomically Precise Metal Oxido Nanoclusters from Combined Pair Distribution Function and Small‐Angle X‐ray Scattering Analysis

The combination of in situ pair distribution function (PDF) analysis and small-angle X-ray scattering (SAXS) enables analysis of the formation mechanism of metal oxido nanoclusters and cluster–solvent interactions as they take place. Herein, we demonstrate the method for the formation of clusters with a [Bi38O45] core. Upon dissolution of crystalline [Bi$_6$O$_5$(OH)$_3$(NO$_3$)$_5$]⋅3 H$_2$O in DMSO, an intermediate rapidly forms, which slowly grows to stable [Bi$_{38}$O$_{45}$] clusters. To identify the intermediate, we developed an automated modeling method, where smaller [BixOy] structures based on the [Bi$_{38}$O$_{45}$] framework are tested against the data. [Bi$_{22}$O$_{26}$] was identified as the main intermediate species, illustrating how combined PDF and SAXS analysis is a powerful tool to gain insight into nucleation on an atomic scale. PDF also provides information on the interaction between nanoclusters and solvent, which is shown to depend on the nature of the ligands on the cluster surface

Structural Changes during the Growth of Atomically Precise Metal Oxido Nanoclusters from Combined Pair Distribution Function and Small‐Angle X‐ray Scattering Analysis

The combination of in situ pair distribution function (PDF) analysis and small-angle X-ray scattering (SAXS) enables analysis of the formation mechanism of metal oxido nanoclusters and cluster–solvent interactions as they take place. Herein, we demonstrate the method for the formation of clusters with a [Bi38O45] core. Upon dissolution of crystalline [Bi$_6$O$_5$(OH)$_3$(NO$_3$)$_5$]⋅3 H$_2$O in DMSO, an intermediate rapidly forms, which slowly grows to stable [Bi$_{38}$O$_{45}$] clusters. To identify the intermediate, we developed an automated modeling method, where smaller [BixOy] structures based on the [Bi$_{38}$O$_{45}$] framework are tested against the data. [Bi$_{22}$O$_{26}$] was identified as the main intermediate species, illustrating how combined PDF and SAXS analysis is a powerful tool to gain insight into nucleation on an atomic scale. PDF also provides information on the interaction between nanoclusters and solvent, which is shown to depend on the nature of the ligands on the cluster surface