Abstract
The global regulators agr and sar control expression of cell wall and extracellular proteins. Inactivation of either sar and/or agr in a typical heterogeneously methicillin-resistant ...Staphylococcus aureus resulted in a small but reproducible decrease in the number of cells in the subpopulation expressing high methicillin resistance. The amount of low affinity penicillin-binding protein PBP2′, the prerequisite for methicillin resistance, was apparently not affected, however, a reduction in PBP1 and PBP3 production was observed, suggesting that these resident PBPs of the cells might be involved somehow together with PBP2′ in high level methicillin resistance.
High-density BaTiO3 ceramics with homogeneous fine-grained microstructure were obtained by incorporating small amounts of SiO2, P2O5 and ZnO and sintering at temperatures between 1175 and 1225 C. ...Dilatometry and porosimetry tests showed that sintering starts at a higher temperature (around 200 C higher) for the doped material. As a consequence, porosity coalescence and removal is promoted while grain growth is inhibited during the first sintering step. SEM and TEM analysis did not reveal any secondary phases in the microstructure of the samples sintered below 1250 C. Grain growth control and microstructural homogeneity seem related to the dopant distribution. XPS analysis showed that the dopants are distributed on the surface of the BaTiO3 particles before the temperature at which sintering starts is reached. The behaviour of the Curie temperature indicates that dopants are incorporated as a solid solution after sintering below 1250 C. This incorporation may lead to compositional changes at the grain boundaries. 10 refs.
Extract: The microbiological quality of fresh blue crabmeat, soft- and hardshell clams, and shucked Eastern oysters was determined at the retail (crabmeat, oysters) and wholesale (clams) levels. ...Geometric means of aerobic plate counts incubated at 35 degrees C were: blue crabmeat 140,000 colony-forming units (CFU)/g, hardshell clams 950 CFU/g, softshell clams 680 CFU/g and shucked Eastern oysters 390,000 CFU/g. Coliform geometric means ranged from 3.6/100 g for hardshell clams to 21/g for blue crabmeat. Means for fecal coliforms or Escherichia coli ranged from less than 3/100 g for clams to 27/100 g for oysters. The mean Staphylococcus aureus count in blue crabmeat was 10/g. (author)
The scope of this paper is to report the results obtained about the solid state phase relations in the interfacial region for a system consisting of Y2O3-modified CeO2 solid electrolyte and ...Y0.7Ca0.3MnO3-based ceramic electrode. The ceria–yttria solid electrolyte has been doped with CaO for improving the grain boundary conductivity, according to the results described elsewhere. The electrode was fixed on the electrolyte by powder pressing and the sandwich was cofired at several temperatures. The microstructure was observed with Scanning Electron Microscopy (SEM), and the reaction products were established by X-Ray Diffraction (XRD) of the cofired materials. Complex Impedance Spectroscopy was used for determining the total electrical conductivity and the electrical behaviour of the interphase electrode–electrolyte. The boundary region between the electrode and the electrolyte showed no reaction phases. The complex impedance measurements indicate that the (Y,Ca) manganites have the conductivity comparable to that of the Ag electrodes.
This paper describes the preparation of homogeneous Bi7Ti4NbO21 single‐phase ceramic powders of ∼55 nm crystallite size, at temperatures as low as 400°–500°C using a metal citrate complex method ...based on the Pechini‐type reaction route. The thermal decomposition/oxidation of the polymerized resin, as investigated by TG/DTA, XRD, and SEM, led to the formation of a well‐defined orthorhombic Bi7Ti4NbO21 compound with lattice parameters a= 0.544, b= 0.540, and c= 2.905 ± 0.0005 nm. Reaction takes place through an intermediate binary phase with a stoichiometry close to Bi20TiO32 which forms between 300° and 375°C. The metal‐organic precursor synthesis method, where Bi, Ti, and Nb ions are first chelated to form metal complexes and then polymerized to give a gel, allows control of the Bi/Ti/Nb stoichiometric ratio leading to the rapid formation of nanosized bismuth titanate niobate (Bi7Ti4NbO21) ceramic powders, at temperatures much lower than usually needed by conventional processing of mixed‐oxide powders.
This thesis analyses a shift in the history of experimental writing during which literary experimentation stopped being circumscribed by the historical avant-gardes and adopted a more democratic, ...ludic and inclusive approach to the textual experience: what I will term an experimentalism. In order to illuminate this shift I will explore works written in Paris by Julio Cortázar and Italo Calvino between 1963 and 1973, including Cortázar's Rayuela (1963) Hopscotch (1966), 62: Modelo para armar (1968) 62: A Model Kit (1972) and Libro de Manuel (1973) A Manual for Manuel (1978), and Calvino's Le cosmicomiche (1965) Cosmicomics (1968), Il castello dei destini incrociati (1969) The Castle of Crossed Destinies (1976) and Le città invisibili (1972) Invisible Cities (1974). I will also pay special attention to their collaboration, La fosse de Babel (1972), as it combines their experimentalisms and is pivotal to the shift I theorise. I will read this development of the experimental as a product of a history that begins with Émile Zola's Le Roman Experimental (1880), through which the novel became a laboratory for social experiment, changing with the emergence of the historical avant-gardes between the 1910s and 1930s, as the experiment focused on language in order to challenge tradition and the establishment. I will offer a revision of Umberto Eco's reading on this shift while challenging his ideas on the open work. This will allow me to undertake a comparative study of Cortázar's and Calvino's experimental writings in Paris, where other new avant-garde groups such as the nouveau roman writers were publishing innovative novels and members of the Oulipo were exploring the potentiality of literary constraints. I will, however, contend that the events of May '68 triggered a point of no return for their experimental practices. Influenced by the Cuban revolution, Cortázar developed his revolutionary poetics further, while Calvino continued to play with combinatorial inventiveness, vouchsafing his membership in the Oulipo in 1973. Such a comparison will provide a contextual understanding to these authors' experimentalisms at the same time that will venture a re-examination of its political and critical meanings.
This thesis analyses a shift in the history of experimental writing during which literary experimentation stopped being circumscribed by the historical avant-gardes and adopted a more democratic, ...ludic and inclusive approach to the textual experience: what I will term an experimentalism. In order to illuminate this shift I will explore works written in Paris by Julio Cortázar and Italo Calvino between 1963 and 1973, including Cortázar’s Rayuela (1963) Hopscotch (1966), 62: Modelo para armar (1968) 62: A Model Kit (1972) and Libro de Manuel (1973) A Manual for Manuel (1978), and Calvino’s Le cosmicomiche (1965) Cosmicomics (1968), Il castello dei destini incrociati (1969) The Castle of Crossed Destinies (1976) and Le città invisibili (1972) Invisible Cities (1974). I will also pay special attention to their collaboration, La fosse de Babel (1972), as it combines their experimentalisms and is pivotal to the shift I theorise. I will read this development of the experimental as a product of a history that begins with Émile Zola’s Le Roman Experimental (1880), through which the novel became a laboratory for social experiment, changing with the emergence of the historical avant-gardes between the 1910s and 1930s, as the experiment focused on language in order to challenge tradition and the establishment. I will offer a revision of Umberto Eco’s reading on this shift while challenging his ideas on the open work. This will allow me to undertake a comparative study of Cortázar’s and Calvino’s experimental writings in Paris, where other new avant-garde groups such as the nouveau roman writers were publishing innovative novels and members of the Oulipo were exploring the potentiality of literary constraints. I will, however, contend that the events of May ’68 triggered a point of no return for their experimental practices. Influenced by the Cuban revolution, Cortázar developed his revolutionary poetics further, while Calvino continued to play with combinatorial inventiveness, vouchsafing his membership in the Oulipo in 1973. Such a comparison will provide a contextual understanding to these authors’ experimentalisms at the same time that will venture a re-examination of its political and critical meanings.
Pb(Zn
1/3
Nb
2/3
)O
3
‐based ceramics have been prepared by two different processing methods: conventional (PZN‐C) and reaction‐sintering (PZN‐RS). The conventionally prepared PZN‐based ceramics ...densified at lower temperatures (950°C) than the reaction‐sintered samples (1100°C), but the perovskite/pyrochlore ratio was always higher in PZN‐RS. The presence of a substantial amount of pyrochlore phase in PZN‐C ceramics caused a decrease in the electrical properties. The maximum dielectric constant values in PZN‐C ceramics were 10%–15% lower than those of PZN‐RS, despite a similar average grain size, 7 ± 0.2 μm. The temperature of the maximum of the dielectric constant (
T
max
) was lower than that expected from the mixing rule because of the possible formation of Ba–Nb clusters. The higher chemical homogeneity in PZN‐RS ceramics is the main reason for the higher dielectric constant,
T
max
and electromechanical response, as well as for the lower difference between
T
max
and the depolarization temperature (
T
d
) and the lower diffusiveness parameter (δ).
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