Displacements of Multiblock Geotechnical Structures Subjected to Seismic Excitation

A method is presented for calculations of irreversible displacements of multiblock structures subjected to seismic excitation. Use is made of the kinematic approach of limit analysis. To make the analysis tractable a hodograph representing distribution of accelerations in the structure is introduced. Distinction is made between soils conforming to the associative and nonassociative flow rules, and the importance of this distinction is demonstrated. The yield acceleration calculated for slopes comprised of soils conforming to the nonassociative flow rule is lower than that for a soil with the same strength parameters, but its deformation governed by the associative flow rule. Consequently, the displacements predicted for the former are larger. An example of a slope is demonstrated, but the method presented is applicable to other structures, such as retaining walls and embankments.     

Dynamic buckling of thin-walled viscoplastic columns

The purpose of this paper is the analysis of strain-rate effect in dynamic stability of thin-walled orthotropic column of closed rectangular cross-section, subjected to in-plane pulse loading of finite duration. For the solution the first-order shear deformation theory displacement field is employed with the Green–Lagrange strain tensor application. The effect of strain rate sensitivity is included in the framework of the viscoplasticity constitutive Perzyna model for material behaviour under high strain rate loading. The numerical results are obtained with the finite element method application. In the performed analysis the strain-rate effect influence on the dynamic buckling load is examined as well as the initial imperfections of walls, pulse shape and the orthotropy ratio are considered. The results of dynamic criteria application are compared furthermore.     

Power scaling of a fiber master oscillator power amplifier system using a coherent polarization beam combination

A new coherent polarization beam combination (CPBC) architecture was employed to combine four amplified beams and produce over 25 W of coherent output with 94% efficiency and nearly diffraction-limited beam quality. The individual beams were produced by a fiber master oscillator power amplifier system and their phases were controlled and locked using servo-controlled phase modulators. The CPBC approach relies on a coherent superposition of orthogonal polarization states and allows the combination of an arbitrary number of beams with arbitrary power ratios.     

Influence of annealing on the structure and stoichiometry of europium-doped titanium dioxide thin films

This work presents the influence of annealing on the structure and stoichiometry of europium (Eu)-doped titanium dioxide (TiO₂). Thin films were fabricated by magnetron sputtering from a metallic Ti-Eu target in oxygen atmosphere and deposited on silicon and SiO₂ substrates. After deposition the selected samples were additionally annealed in air up to 1070 K.Film properties were examined by means of X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) and the results were analyzed together with the undoped TiO₂ thin films prepared under similar technological conditions.XRD results showed that depending on the Eu content, as-deposited thin films consisted of the TiO₂-anatase or TiO₂-rutile.An additional annealing will result in the growth of anatase crystals up to 35 nm, but anatase to rutile phase transformation has not been recorded. AFM images display high quality and a dense nanocrystalline structure. From the XPS Ti2p spectra the 4+oxidation state of Ti was confirmed. The O1s XPS spectra displayed the presence of an O²⁻ photoelectron peak accompanied by an additional broader peak that originates from hydroxyl species chemisorbed at the sample surface. It has been found that Eu dopant increases the OH⁻ content on the surface of prepared TiO₂:Eu thin films. The calculated O/Ti ratio was in the range of 1.85-2.04 depending on the sample.     

Electrochemistry and spectroelectrochemistry of a novel selenophene-based monomer

A stereocontrolled synthesis of a novel selenophene-based monomer namely (E,E)-1,4-dimethoxy-2,5-bis[2-(selenophen-2-yl)ethenyl]benzene has been successfully performed starting from 1,4-dimethoxybenzene. Its spectra, electrochemistry and polymerization have been studied.     

Non-carcinogenic carbon sorbents for respiratory protection

Activated carbons impregnated with compounds of chromium, copper and silver (Cr-Cu-Ag) are widely used for removing toxic substances from air, mainly in respiratory protection for industrial and military applications. Toxicological and epidemiological studies have shown chromium (especially hexavalent Cr) to have carcinogenic properties. Hence, research has been launched to develop a new adsorption-catalytic complex without chromium, which is intended to replace the activated carbon-catalyst (Cr-Cu-Ag) system. In this work activated carbon obtained from plum stones as carrier and molybdenum, copper and silver salts as impregnates were studied. The porous structure of the carbon carrier was investigated using low temperature nitrogen adsorption. Cyanogen chloride breakthrough dynamics was analyzed in order to characterize the protection properties. Studies on the substitution of chromium by non-carcinogenic metals will be continued.     

PD-L1 Inhibitors: Different Classes,Activities, and Mechanisms of Action

Targeting the programmed cell death protein 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) interaction has become an established strategy for cancer immunotherapy. Although hundreds of small-molecule, peptide, and peptidomimetic inhibitors have been proposed in recent years, only a limited number of drug candidates show good PD-1/PD-L1 blocking activity in cell-based assays. In this article, we compare representative molecules from different classes in terms of their PD-1/PD-L1 dissociation capacity measured by HTRF and in vitro bioactivity determined by the immune checkpoint blockade (ICB) co-culture assay. We point to recent discoveries that underscore important differences in the mechanisms of action of these molecules and also indicate one principal feature that needs to be considered, which is the eventual human PD-L1 specificity.     

Hydrogel of biodegradable cellulose derivatives. I. Radiation‐induced crosslinking of CMC

Radiation crosslinking of carboxymethylcellulose (CMC) with a degree of substitution (DS) from 0.7 to 2.2 was the subject of the current investigation. CMC was irradiated in solid‐state and aqueous solutions at various irradiation doses. The DS and the concentration of the aqueous solution had a remarkable affect on the crosslinking of CMC. Irradiation of CMC, even with a high DS, 2.2 in solid state, and a low DS, 0.7 in 10% aqueous solution, resulted in degradation. However, it was found that irradiation of CMC with a relatively high DS, 1.32, led to crosslinking in a 5% aqueous solution, and 20% CMC gave the highest gel fraction. CMC with a DS of 2.2 induced higher crosslinking than that with a DS of 1.32 at lower doses with the same concentration. Hence, it was apparent that a high DS and a high concentration in an aqueous solution were favorable for high crosslinking of CMC. It is assumed that high radiation crosslinking of CMC was induced by the increased mobility of its molecules in water and by the formation of CMC radicals from the abstraction of H atoms from macromolecules in the intermediate products of water radiolysis. A preliminary biodegradation study confirmed that crosslinked CMC hydrogel can be digested by a cellulase enzyme. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 278–283, 2000