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Grazing incidence x-ray diffraction and reflectivity measurements were carried out on ultrathin (a few unit cells thick) superconducting heterostructures, based on Ba0.9Nd0.1CuO(sub 2+x) and CaCuO2 individual blocks, using undulator radiation from a third-generation synchroton. This analysis shows that the interfaces between the different constituent blocks are very sharp with roughness less than one unit cell.

We have grown LaMnO3 thin films on (001) LaAlO3 substrates by pulsed laser deposition. X-ray diffraction confirms that the films are only slightly relaxed and are oriented “square on square” relative to the substrate. The measured Raman spectra closely resemble that observed in bulk LaMnO3, which indicates no relevant distortions of the MnO6 octahedra induced by the epitaxial strain. Therefore, no detectable changes in the lattice dynamics occurred in our LaMnO3 strained films relative to the bulk case. 55Mn nuclear magnetic resonance identifies the presence of localized Mn4+ states. Superconducting quantum interference device magnetization measures TN=131(3) K and a saturation moment μ=1.09μB/Mn, revealing a small concentration of Mn4+ and placing our films within the antiferromagnetic insulating phase. [ABSTRACT FROM AUTHOR]

In this paper, we illustrate an approach to discriminate between epitaxial strain and other factors responsible for the decrease of the metal–insulator transition temperature (TP) in thin La0.7Sr0.3MnO3 films grown by pulsed laser deposition. Using this approach, we have estimated the effect of the biaxial strain on TP. Ultrathin films, independent of epitaxial strain, do not show any metal–insulator transition over the full temperature range. This finding confirms the existence of an interface dead layer. The strain-independent decrease in TP, relative to its bulk value, observed for a much wider thickness range (up to about 1000 Å) can most likely be attributed to oxygen deficiency. [ABSTRACT FROM AUTHOR]

Thin films of LaMn[O.sub.3] (LMO) compounds were prepared by pulsed laser deposition and characterized through x-ray diffraction measurements. The study demonstrates that the epitaxial strain does not induce relevant tilting or rotation of the Mn[O.sub.6] octahedra enough to influence the observed Raman spectra, which did not show any sizable shift or broadening of peaks relative to the typical bulk spectra.

An approach to discriminate between epitaxial strain and other factors responsible for the decrease of the metal-insulator transition temperature (T(sub p)) in thin La(sub 0.7)Sr(sub 0.3)MnO(sub 3) films grown by pulsed laser deposition is presented. The effects of the biaxial strain on T(sub p) are estimated by using this approach.

We report on a Raman study of the phonon spectrum of La 0.7Sr0.3MnO3 thin films epitaxially grown on LaAlO3. The spectrum, as a function of film thickness d, does not change over the 1000–100 Å range, whereas a strong hardening of the phonon frequencies of both bending and stretching modes is apparent in ultra-thin films (d<100 Å) where substrate-induced effects are remarkable. This behaviour, which appears to be related with the measured d-dependence of the insulator-to-metal transition temperature, is ascribed to co-operative effects of MnO6 octahedra rotation and charge-localization. Raman spectroscopy proves to be a simple and powerful tool to monitor subtle structural modifications hardly detectable with conventional diffraction techniques in ultra-thin films. [ABSTRACT FROM AUTHOR]

Structural investigation using X-ray synchrotron radiation has been performed on SrRuO3/SrTiO3/SrRuO3 epitaxial heterostructures, with each constituent layer a few unit cell thick grown on (001) SrTiO3 substrate. Detailed information on the evolution of the in-plane lattice structure has been obtained, in these heterostructures, by grazing incidence diffraction measurements. The samples have been grown by low-pressure pulsed laser deposition. Under our deposition conditions, SrRuO3 layers grow with an elongated cell perpendicular to the substrate surface. The in-plane pseudocubic lattice parameters do not match the in-plane square SrTiO3 structure even in the case of very thin SrRuO3 layers. Such a distortion was found to decrease with increasing the thickness of the SrTiO3 barrier layer. [ABSTRACT FROM AUTHOR]

Presents the results of a study on the infrared phonons in the La0.7Sr0.3MnO3 manganite using reflectance measurements on epitaxial films. Relationship between the manganite phonon spectrum and the substrate and film thickness; Role of the thick films measurements in the determination of line profile and the peak-frequency of the bending and stretching of phonons.

In order to investigate the relationship between oesophageal motor abnormalities and oesophagitis, we carried out four hour studies of oesophageal motility and 24 hour pH measurements in fasting and fed conditions in eight patients before, during (pH only), and after medical healing of erosive oesophagitis. Gastrooesophageal acid reflux decreased (ns) during the treatment, but tended to return to basal values at the end. Oesophageal body motility was unchanged after healing, while the lower oesophageal sphincter basal tone was significantly increased at the end of the study in the postcibal period. The results suggest that the impairment of the sphincter tone in reflux oesophagitis is secondary to the presence of the oesophageal lesions. Macroscopic healing is not paralleled by improved major pathogenic factors of the disease, however--that is, acid reflux and oesophageal body motility. [ABSTRACT FROM PUBLISHER]

Summarizes a case investigation of lead poisoning in children associated with litargirio use in Rhode Island in 2003. Information on a statewide health alert issued by the Rhode Island Department of Health regarding the use of litargirio; Reason behind the failure of certain ethnic populations to disclose the use of the product; Limitations of the convenience survey conducted to assess litargirio use in the Hispanic community in Providence.