Structural phase transition and high temperature phase structure of Friedels salt, 3CaO · Al2O3 · CaCl2 · 10H2O

Friedels salt, the chlorinated compound 3CaO · Al₂O₃ · CaCl₂ · 10H₂O (AFm phase), presents a structural phase transition at about 30°C from a monoclinic to a rhombohedral phase. It has been studied by X-ray powder diffraction and optical microscopy in transmitted light with crossed polarisers on single crystals prepared by hydrothermal synthesis. The high temperature phase was determined at 37°C from X-ray single crystal diffraction data. The compound crystallises in the space group R c with lattice parameters of a = 5.7358(6)Å and c = 46.849(9)Å (Z = 3 and D_x = 2.111 g/cm³). The refinement of 498 independent reflections with I > 2σ(I) led to a residual factor of 7.1%. The Friedels salt can be described as a layered structure with positively charged main layers of composition [Ca₂Al(OH)₆]⁺ and negatively charged layers of composition [Cl⁻,2H₂O]. The chloride anions are surrounded by 10 hydrogen atoms, of which six belong to hydroxyl groups and four to water molecules. The structural phase transition may be related to the size of the chloride anions, which are not adapted to the octahedral cavity formed by bonded water molecules.     

Analysis of inter-tap correlation for measured mobile radio channels at 1.9 GHz

Tapped-delay line representations are analysed by presenting an empirical model relating the inter-tap correlation to the tap powers obtained from pedestrian radio channel impulse responses measured at 1.9 GHz. The impact of the filtering bandwidth on the parameters of this model is also investigated.     

Featured‐Based Registration of Terrestrial Laser Scans with Minimum Overlap Using Photogrammetric Data

Currently, there is a considerable interest in 3D object reconstruction using terrestrial laser scanner (TLS) systems due to their ability to automatically generate a considerable amount of points in a very short time. To fully map an object, multiple scans are captured. The different scans need to be registered with the help of the point cloud in the overlap regions. To guarantee reliable registration, the scans should have large overlap ratio with good geometry for the estimation of the transformation parameters among these scans. The objective of this paper is to propose a registration method that relaxes/eliminates the overlap requirement through the utilization of photogrammetrically reconstructed features. More specifically, a point‐based procedure, which utilizes non‐conjugate points along corresponding linear features from photogrammetric and TLS data, will be used for the registration. The non‐correspondence of the selected points along the linear features is compensated for by artificially modifying their weight matrices. The paper presents experimental results from simulated and real datasets to illustrate the feasibility of the proposed procedure.     

Interface properties in granular compound films studied by Mössbauer spectroscopy

The nature of iron atoms in granular iron compounds (FeSiO₂, FeAl₂O₃, FeZrO₂) was studied by the Mössbauer effect. Granular compounds with a low concentration of iron are almost amorphous and exhibit a large distribution of hyperfine parameters. Superparamagnetism occurs, the transition temperature depending on the diameter of the grains. The behaviour of iron in granular samples depends on the nature of the insulating matrix.     

Dephosphorylation activates the purified plant plasma membrane H+-ATPase--possible function of phosphothreonine residues in a mechanism not involving the regulatory C-terminal domain of the enzyme

The plasma membrane H+-ATPase was purified from tobacco cells (line BY-2). After solubilization by lysophosphatidylcholine followed by separation on a glycerol gradient, a fraction with a high specific activity of 9 micromol ATP x min(-1) x mg protein(-1) was obtained, in which the H+-ATPase polypeptide represented at least 80% of the protein. The incubation of this fraction in the presence of alkaline phosphatase increased H+-ATPase activity by 40%, in a manner consistent with dephosphorylation of the enzyme itself. The hydrolytic activity of the solubilized enzyme and its proton translocating activity, after reconstitution into proteoliposomes, were stimulated to the same extent. Alkaline phosphatase treatment was also accompanied by a 92% decrease in the H+-ATPase phosphothreonine content, whereas the phosphoserine residues were almost unaffected. The dephosphorylation induced a slight decrease of the affinity of the enzyme towards ATP. The purified enzyme was not activated by lysophosphatidylcholine addition nor by trypsin-mediated proteolysis, two treatments reported to release the inhibitory control by the C-terminal domain of the H+-ATPase and to increase the affinity of the enzyme towards ATP. Based on these results, the regulatory phosphorylation evoked by alkaline phosphatase most likely differs from the autoinhibitory control of the H+-ATPase by its C-terminal domain.     

La technologie asynchrone au service de la réduction d’énergie dans les systèmes embarqués

This article presents the benefits of asynchronous systems versus synchronous systems in term of energy reduction in the context of embedded systems and in particular for telecom equipments such as mobile communicating objects. The electrical consumption reduction is obtained at the hardware and software levels. The shutdown technique and the dynamic voltage scaling for asynchronous systems are studied and compared to synchronous systems. Finally, a power management policy is proposed for asynchronous microprocessors processing periodic and sporadic tasks.     

In vitro activity of BAY 12-8039, a new fluoroquinolone against mycoplasmas

The in vitro activity of the fluoroquinolone BAY 12-8039 against 66 strains of different mycoplasma species and 30 strains of Ureaplasma urealyticum was compared with those of three other antimicrobial agents. BAY 12-8039 at 0.5 microg/ml inhibited 100% of all the mycoplasmal and ureaplasmal strains tested. The minimal bactericidal concentrations of BAY 12-8039 increased only two- to eightfold compared to the MICs. Furthermore, they were comparable to those of sparfloxacin and lower than those of doxycycline and clarithromycin.     

Influence of the status of the contralateral carotid artery on the outcome of carotid surgery

This is a preliminary report of four cases of meniscal displaced tears: two bucket handle medial meniscus tears, one complex tear in the avascular zone or lateral meniscus, and one longitudinal full-thickness tear on the lateral meniscus. These tears were treated by applying hi-frequency current stimulation to the tissues and obtaining total meniscal visual healing on a second arthroscopic view after 6 weeks.