87,905 research outputs found
The activity of indigo carmine against bacteriophages: an edible antiphage agent
No full textIn this dataset, raw data is provided for four different experiments and sub-experiments by the name of Figure 1a-c, figure 2a-b, figure 4a-f, and figure 5a-b. The data is the experiment value (i.e., the concentration of phages/ bacteria) obtained after taking the average of three biological repetitions of either phage titration or cell plating.</p
Secondary ion mass spectrometry and optical characterization of Ti : LiNbO3 optical waveguides
No full textSecondary ion mass spectrometry (SIMS) and m-lines spectroscopy have been applied to study Ti:LiNbO3 slab optical waveguides with high titanium surface concentration. By combining the two techniques, a saturation in the dependence of the refractive index change on the dopant concentration has been found. By the use of SIMS in image mode, the lateral diffusion of titanium in Ti:LiNbO3 channel waveguides has been observed and analyzed
Correlation between optical and compositional properties of Ti : LiNbO3 channel optical waveguides
No full textOptical, compositional, and structural characterization of titanium-diffused LiNbO3 channel waveguides has been performed. The refractive index profiles have been reconstructed from near field measurements using a well-adapted mathematical approximation. Crystal lattice deformations have been measured by x-ray diffraction. Titanium concentration profiles measured by secondary ion mass spectrometry have been correlated to the refractive index profiles. The correlation between compositional, structural, and optical properties is discussed
Characterization of waveguides obtained by proton exchange on a LiNbO3 substrate
No full textWaveguides obtained by proton exchange in LiNbO3 were characterized by Secondary Ion Mass Spectrometry and m-lines technique. Additional micro-Raman investigations evidenced marked changes in the spectra of the waveguide with respect to the substrate. This suggests that micro-Raman spectroscopy may constitute a direct non-destructive method to determine the depth of the exchanged layer, with a limit which is set by the diffraction-limited spot size
Etching effect on periodic domain structures of lithium niobate crystals
No full textIn order to improve the knowledge of the domain structure in LiNbO crystals, the effect of the etching process with HF : HNO (1 : 2 by vol.) has been studied. It has been found, by analyzing the superficial composition with the secondary ion mass spectrometry technique, that during the etching treatment, the fluorine ion diffuses into the crystal, mainly along the positive ferroelectric domain
Erbium incorporation in LiNbO3 crystals obtained by ion-exchange process
No full textErbium local doping of LiNbO3 single crystal by the ion-exchange has been performed. The role of the process parameters such as exchange time and temperature, crystal cut direction, composition and heating rate of the Er ions liquid source has been investigated by means of secondary ion mass spectrometry, X-ray diffraction and micro-lumi- nescence techniques. A theoretical model has been presented for describing the ion-exchange process and has been successfully applied to fit the experimental data. We have demonstrated that the method is suitable for Er-doping of LiNbO3 crystals, with the possibility of tailoring the optical performances of the material through the preparation parameters
Silver and gold doping of SiO2 glass by solid-state field-assisted diffusion
No full textIn this work, a solid-state field-assisted diffusion technique is used to induce diffusion of silver or gold ions into a silica matrix. The obtained systems are characterized by secondary ion mass spectrometry and Rutherford backscattering spectrometry. The metal/glass interface chemistry plays an important role in the behavior of the metals and, especially for Ag, a proper time is required for the deposited film to first oxidize and then diffuse into the matrix, owing to the external electric field. Diffusion of Ag in silica is observed to be very sensitive to the applied field at relatively high temperatures, being stopped when a high field value is applied. This behavior may be attributed to the low availability of sites and the build-up of local electric fields within the glass. As for gold, a quite peculiar behavior of the current density during the process was recorded, indicating that its behavior is even more complex than one could expect. In general, the presented preliminary experimental observations demonstrate the potential of the technique
Dimer assembly of SadA.
No full text<p><b><i>A</i></b>, Ribbon representation of the SadA dimer in an asymmetric unit. The two protomers A and B are colored cyan and wheat, respectively. The loop between α5 and β4 is colored yellow. <b><i>B</i></b>, The disulfide linkage is shown as a stick model in the dimeric structure. The salt bridges of Asp105-Arg102 (<b><i>C</i></b>) and Lys171-Asp87 (<b><i>D</i></b>), the hydrophobic amino acids (<b><i>E</i></b>) and the hydrogen bonds (<b><i>F</i></b>) are shown as white sticks. Distances are given in angstroms.</p
Diffusion behavior of transition metals in field-assisted ion-exchanged glasses
No full textThe use of ion-exchange techniques for doping silicate glasses with transition metals has attracted much attention in the last decades for its potential in several applications, namely, light waveguides technology, luminescent materials, and for the possibility to realize systems in which metal nanocluster formation is controlled by suitable post-exchange techniques. In this framework, the control of metal distribution inside the glass is a central issue for both the understanding of the incorporation process and for the definition of effective preparation protocols. In this experiment, metallic films (Ag, Cu, Au, Co) were deposited onto the substrates by the rf-sputtering technique. Metal ions then penetrate to substitute glass alkali by means of field-assisted ion-exchange, realized at different temperature and electric field values. In particular, we present in this paper the Au doping of silicate glasses, successfully realized for the first time with this method. The gold diffusion profiles, as measured by Secondary Ion Mass Spectrometry (SIMS), indicate that the migration depends on the experimental parameters (temperature and electric field), but also on the local structure, as well as on chemical phenomena occurring at the metal/glass interface
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