Search results for "21"
showing 10 items of 34876 documents
Cryo-EM structure of ssDNA bacteriophage ΦCjT23 provides insight into early virus evolution.
2022
AbstractThe origin of viruses remains an open question. While lack of detectable sequence similarity hampers the analysis of distantly related viruses, structural biology investigations of conserved capsid protein structures facilitate the study of distant evolutionary relationships. Here we characterize the lipid-containing ssDNA temperate bacteriophage ΦCjT23, which infects Flavobacterium sp. (Bacteroidetes). We report ΦCjT23-like sequences in the genome of strains belonging to several Flavobacterium species. The virion structure determined by cryogenic electron microscopy reveals similarities to members of the viral kingdom Bamfordvirae that currently consists solely of dsDNA viruses wit…
The Importance of Empowerment in Entrepreneurship
2017
Empowerment comes at a time when global competition and change require people to take initiative and be innovative. Based on the active, persistent, and change-oriented behaviors associated with psychological empowerment, the chapter states that empowerment can contribute to entrepreneurship. The dimensions of empowerment that suggest a theoretical and empirical link with entrepreneurial behavior are discussed. Several propositions regarding the interplay between empowerment and entrepreneurship are formulated. The chapter describes paths to promote empowerment and entrepreneurship in applied context and suggests future directions to advance research on empowerment in the field of entrepren…
FRCM systems for strengthening masonry structures
2017
Composite materials have been widely used for strengthening weak masonry buildings. Particularly, wrapping with fibre reinforced polymer (FRP) composites has become a common method for strengthening masonry members primarily subjected to compressive static loads or seismic actions. More recently, in an effort to alleviate some drawbacks associated with the use of FRP materials, fibrereinforced cementitious matrix (FRCM) composites have received a lot of interests for external strengthening of historical masonry structures. It is used as an alternative to FRP in situations where these composites have shown some disadvantages or their use is banned. This paper presents a literature review on …
Use of Density Functional Based Tight Binding Methods in Vibrational Circular Dichroism.
2018
Vibrational circular dichroism (VCD) is a spectroscopic technique used to resolve the absolute configuration of chiral systems. Obtaining a theoretical VCD spectrum requires computing atomic polar and axial tensors on top of the computationally demanding construction of the force constant matrix. In this study we evaluated a VCD model in which all necessary quantities are obtained with density functional based tight binding (DFTB) theory. The analyzed DFTB parametrizations fail at providing accurate vibrational frequencies and electric dipole gradients but yield reasonable normal modes at a fraction of the computational cost of density functional theory (DFT). Thus, by applying DFTB in comp…
“Sweet” ionic liquid gels: materials for sweetening of fuels
2018
The search for new materials to be used in desulfurisation (sweetening) of fuels is one of the main topics of current research. In this paper, we explored the possibility of using supramolecular gels obtained from the gelation of ionic liquid binary mixtures. Indeed, some ionic liquids are generally known as efficient extraction phases for desulfurisation of fuels. In rare cases, one of their main drawbacks is their partial solubility in the fuel, leading to contamination. Then, their immobilisation due to the formation of a gelatinous network may be a challenge. Ionic liquid gels were obtained by mixing certain [NTf2]−-based ionic liquids (solvents) with the ones of gluconate-based ionic l…
Injection and ultrafast regeneration in dye-sensitized solar cells
2014
Injection of an electron from the excited dye molecule to the semiconductor is the initial charge separation step in dye-sensitized solar cells (DSC's). Though the dynamics of the forward injection process has been widely studied, the results reported so far are controversial, especially for complete DSC's. In this work, the electron injection in titanium dioxide (TiO2) films sensitized with ruthenium bipyridyl dyes N3 and N719 was studied both in neat solvent and in a typical iodide/triiodide (I-/I3 -) DSC electrolyte. Transient absorption (TA) spectroscopy was used to monitor both the formation of the oxidized dye and the arrival of injected electrons to the conduction band of TiO2. Emiss…
Existence of fixed point for GP(Λ;Θ)-contractive mappings in GP-metric spaces
2017
We combine some classes of functions with a notion of hybrid $GP_{(\Lambda,\Theta )}$ - $H$ - $F$ - contractive mapping for establishing some fixed point results in the setting of $GP$-metric spaces. An illustrative example supports the new theory.
Erratum to: Methods of Electron Microdiffraction and X-Ray Analysis in Structure Study of Nanodisperse Partially Stabilized ZrO2 Powders
2019
Analytical electron microscopy (AEM) has been used to study both structure and morphology of partially yttria-stabilized zirconia dioxide nanopowders (YSZ) obtained by wet-chemical methods (glycine and azeotropic distillation) and ceramics produced from them. Both morphological and structural inhomogeneity of nanopowders obtained by glycine (glc) method has been estimated. Besides the tetragonal ZrO2 phase (results of X-ray analyses) the cubic phase of ZrO2 with different degree of crystallinity has been estimated by Electron Microdiffraction (EMD) methods. In powders obtained by azeotropic distillation (dest) method besides the amorphous phase (identified in X-ray investigations) the high …
Optical detection of paramagnetic centres in activated oxyfluoride glass-ceramics
2018
Electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD) and EPR detected via MCD (MCD-EPR) investigations have been performed on rare-earth activated oxyfluoride glasses and glass-ceramics. Er3+, Gd3+, and Mn2+ activators in oxyfluoride glass-ceramics show paramagnetic MCD behaviour and the MCD-EPR has been detected. The results of the MCD-EPR measurements for the Er-doped oxyfluoride glass-ceramics showed that Er3+ ions in the CaF2 crystallites in these ceramics embed only in the cubic symmetry environment, similarly to the previous observations of cubic Gd3+ centres in the glass-ceramics containing CaF2. Finally, the correlation of optics and paramagnetic centres is discu…
Effect of space charge on the negative oxygen flux during reactive sputtering
2017
Negative ions often play a distinctive role in the phase formation during reactive sputter deposition. The path of these high energetic ions is often assumed to be straight. In this paper, it is shown that in the context of reactive magnetron sputtering space charge effects are decisive for the energetic negative ion trajectories. To investigate the effect of space charge spreading, reactive magnetron sputter experiments were performed in compound mode with target materials that are expected to have a high secondary ion emission yield (MgO and CeO2). By the combination of energy flux measurements, and simulations, a quantitative value for the negative oxygen ion yield can be derived.