Quasiballistic transport of Dirac fermions in a Bi2Se3 nanowire.

Quantum coherent transport of surface states in a mesoscopic nanowire of the three-dimensional topological insulator Bi(2}Se(3) is studied in the weak-disorder limit. At very low temperatures, many harmonics are evidenced in the Fourier transform of Aharonov-Bohm oscillations, revealing the long phase coherence length of spin-chiral Dirac fermions. Remarkably, from their exponential temperature dependence, we infer an unusual 1/T power law for the phase coherence length L(φ)(T). This decoherence is typical for quasiballistic fermions weakly coupled to their environment.

Chemical characterization of bohrium (element 107)

The arrangement of the chemical elements in the periodic table highlights resemblances in chemical properties, which reflect the elements' electronic structure. For the heaviest elements, however, deviations in the periodicity of chemical properties are expected: electrons in orbitals with a high probability density near the nucleus are accelerated by the large nuclear charges to relativistic velocities, which increase their binding energies and cause orbital contraction. This leads to more efficient screening of the nuclear charge and corresponding destabilization of the outer d and f orbitals: it is these changes that can give rise to unexpected chemical properties. The synthesis of increasingly heavy elements, now including that of elements 114, 116 and 118, allows the investigation of this effect, provided sufficiently long-lived isotopes for chemical characterization are available. In the case of elements 104 and 105, for example, relativistic effects interrupt characteristic trends in the chemical properties of the elements constituting the corresponding columns of the periodic table, whereas element 106 behaves in accordance with the expected periodicity. Here we report the chemical separation and characterization of six atoms of element 107 (bohrium, Bh), in the form of its oxychloride. We find that this compound is less volatile than the oxychlorides of the lighter elements of group VII, thus confirming relativistic calculations that predict the behaviour of bohrium, like that of element 106, to coincide with that expected on the basis of its position in the periodic table.

Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires.

Disorder remains a key limitation in the search for robust signatures of topological superconductivity in condensed matter. Whereas clean semiconducting quantum wires gave promising results discussed in terms of Majorana bound states, disorder makes the interpretation more complex. Quantum wires of 3D topological insulators offer a serious alternative due to their perfectly-transmitted mode. An important aspect to consider is the mixing of quasi-1D surface modes due to the strong degree of disorder typical for such materials. Here, we reveal that the energy broadening γ of such modes is much smaller than their energy spacing Δ, an unusual result for highly-disordered mesoscopic nanostructures. This is evidenced by non-universal conductance fluctuations in highly-doped and disordered Bi2Se3 and Bi2Te3 nanowires. Theory shows that such a unique behavior is specific to spin-helical Dirac fermions with strong quantum confinement, which retain ballistic properties over an unusually large energy scale due to their spin texture. Our result confirms their potential to investigate topological superconductivity without ambiguity despite strong disorder.

[Economic analysis of home based versus hospital outpatient chemotherapy in stage IV non small cell lung cancer]. / Analyse économique de l'administration d'une chimiothérapie en hospitalisation à domicile (HAD) comparée à l'hospitalisation de jour dans les cancers bronchopulmonaires non à petites cellules de stade IV.

BACKGROUND: French law and government decisions have induced new development for home base treatments. The objective was to compare cost of home base chemotherapy (HBC) versus outpatient infusions, for non small cell lung cancer (NSCLC). METHODS: 10 patients were selected in each category. D8 of their cycles was performed at home compared to outpatient infusion. Costs were based on national fees with cytostatic drugs as supplement. The real cost was also assessed through a specific questionnaire. RESULTS: 30 D8 infusions were carried out at hospital and 24 D8 infusions at home. Average cost by cycle was 2,829.51 euros [2 560.74-3 147.02] for hospital infusion, 2,372.50 euros [1 962.75-2 792.88] for HBC (-16.15%). Difference was -457.01 euros by cycle [-919.74; 26.82]. Real costs by injection for BHC was 484.42 euros [424.18; 540.32] versus a fee of 699.89 euros [643.64; 750.23]. There were no difference in terms of adverse events. CONCLUSION: HBC for NSCLC is feasible. Average costs by cycle is lower of 16% versus hospital infusion. The results of this non randomized study had to be confirm by further clinical trials.

[Post-traumatic pulmonary hematomas. Apropos of 2 cases]. / Hématomes pulmonaires post-traumatiques. A propos de deux observations.

Post-traumatic pulmonary hematoma presents clinically as a hemorrhagic collection within a newly-formed cavity in the lung parenchyma. Its frequency is probably underestimated in view of the importance of the associated lesions. The most frequent clinical sign is hemoptysis. The chest radiograph, as well as the CT scan, shows a clearly defined round image. As a rule, there is a favorable outcome with slow resorption over several weeks, with a restoration of the integrity of the pulmonary parenchyma, which justifies simple observation, with an absence of any therapeutic intervention.

[Skin tests in the exploration of perianesthetic complications]. / Intérêt du bilan cutané dans l'exploration des accidents per-anesthésiques.

Adverse reactions in anesthesia are more and more frequent. The favoring factors are multiple but the physiopathology of these reactions are not right known: non specific histamine-release, complement activation is anaphylaxis can occur. Skin tests are an very important data for the diagnosis of these accidents. Forty patients and ten healthy subjects were tested with systematic research of a cross-reactivity for curare family; myorelaxants, fluid gelatin, dextran are the tests the most frequently positive. Cross reactivity for curare family is sure and sensibilization by some medicine is possible. Then the behavior of the data is looked at; the research of the favoring factors, the non utilization of some substances and prophylactic treatment are recommended.

[Does extrinsic asthma exist?]. / L'asthme extrinsèque existe-t-il?

Asthma cannot be triggered exclusively by external causes, even allergy. For it to develop, the subject must have pathological bronchial hyper-reactivity. On the contrary, however, asthma cannot be explained solely by intrinsic causes, metabolic or endocrine. It persists only in those subjects who have bronchial hyper-reactivity. The authors suggest a new definition of asthma, designed to replace the semi-logical definition of Charpin: Asthma is a dyspnoeic bronchospasmodic crisis that is linked with the existence of pathological bronchial hyper-reactivity.

[Pneumocystis carinii pneumonia radiologically simulating tuberculosis]. / Pneumonie à Pneumocystis carinii simulant radiologiquement une tuberculose.

The authors report a case of Pneumocystis carinii pneumonia simulating tuberculosis. Predominant upper lobes involvement is rarely seen but should be considered in immunocompromised patients.

First Measurement of a Thermochemical Property of a Seaborgium Compound.

With only a few atoms of seaborgium (Sg, element 106), in the form of volatile SgO(2)Cl(2), it was possible to determine the sublimation enthalpy of this compound using gas chromatography. Furthermore, it was demonstrated that in Group 6 Sg is chemically more similar to W than to Mo.

Tracing latitudinal gradient, river discharge and water masses along the subtropical South American coast using benthic Foraminifera assemblages.

More than 30% of Buccella peruviana (D'Orbigny), Globocassidulina crassa porrecta (Earland & Heron-Allen), Cibicides mackannai (Galloway & Wissler) and C. refulgens (Montfort) indicate the presence of cold Sub Antarctic Shelf Water in winter, from 33.5 to 38.3º S, deeper than 100 m, in the southern part of the study area. In summer, the abundance of this association decreases to less than 15% around 37.5-38.9º S where two species (Globocassidulina subglobosa (Brady), Uvigerina peregrina (Cushman) take over. G. subglobosa, U. peregrina, and Hanzawaia boueana (D'Orbigny) are found at 27-33º S in both seasons in less than 55 m deep in the northern part, and are linked with warm Subtropical Shelf Water and Tropical Water. Freshwater influence was signalized by high silicate concentration and by the presence of Pseudononion atlanticum (Cushman), Bolivina striatula (Cushman), Buliminella elegantissima (D'Orbigny), Bulimina elongata (D'Orbigny), Elphidium excavatum (Terquem), E. poeyanum (D'Orbigny), Ammobaculites exiguus (Cushman & Brönnimann), Arenoparrella mexicana (Kornfeld), Gaudryina exillis (Cushman & Brönnimann), Textularia earlandi (Parker) and thecamoebians in four sectors of the shelf. The presence of Bulimina marginata (D'Orbigny) between 34.1-32.8º S in the winter and 34.2-32.7º S in the summer indicates that the influence of the Subtropical Shelf Front on the sediment does not change seasonally, otherwise, the presence of Angulogerina angulosa (Williamson) in the winter, only in Mar del Plata (38.9º S), show that Malvinas currents are not influencing the sediment in the summer.

Characterization of the sterically encumbered terphenyl-substituted species 2,6-Trip2H3C6Sn-Sn(Me)2C6H3-2,6-Trip2, an unsymmetric, group 14 element, methylmethylene, valence isomer of an alkene, its related lithium derivative 2,6-Trip2H3C6(Me)2Sn-Sn(Li)(Me)C6H3-2,6-Trip2, and the monomer Sn(t-Bu)C6H3-2,6-Trip2 (Trip = C6H2-2,4,6-i-Pr3).

The reaction of the recently reported sterically encumbered terphenyl tin(II) halide species Sn(Cl)C6H3-2,6-Trip2 (Trip = C6H2-2,4,6-i-Pr3), 1, with 1 equiv of MeLi or MeMgBr afforded 2,6-Trip2H3C6Sn-Sn(Me)2C6H3-2,6-Trip2, 2, which is the first stable group 14 element methylmethylene (i.e., CH3CH) analogue of ethylene (H2CCH2). Reaction of 1 with 1.5 equiv of MeLi yielded the stannylstannate species 2,6-Trip2H3C6(Me)2Sn-Sn(Li)(Me)-C6H3-2,6-Trip2, 3, whereas reaction of 1 with 1 equiv of t-BuLi gave the heteroleptic stannanediyl monomer Sn(t-Bu)C6H3-2,6-Trip2 (4). The compounds 2-4 were characterized by 1H, 13C (7Li, 3 only), and 119Sn NMR spectroscopy in solution and by UV-vis spectroscopy. The X-ray crystal structures of 2-4 were also determined. The formation of the stannylstannanediyl 2 instead of the expected symmetrical, valence isomer "distannene" form (Sn(Me)C6H3-2,6-Trip2)2, 6, is explained through the ready formation of LiSn(Me)2C6H3-2,6-Trip2, 5, which reacts rapidly with 1 to produce 2 which can then react with a further equivalent of MeLi to give 3. The stability of singly bonded 2 in relation to the formally doubly bonded 6 was rationalized on the basis of the difference in the strength of their tin-tin bonds. In contrast to the methyl derivatives, the reaction of 1 with t-BuLi proceeded smoothly to give the monomeric compound 4. Apparently, the formation of a t-Bu analogue of 5 was prevented by the more crowding t-Bu group. Compound 2 is also the first example of a stable molecule with bonding between a two-coordinate, bivalent tin and four-coordinate tetravalent tin. Both compounds 2 and 3 display large J 119Sn-119Sn couplings between their tin nuclei and the tin-tin bond lengths in 2 (2.8909(2) A) and 3 (2.8508(4) A) are relatively normal despite the presence of the sterically crowding terphenyl substituents.

[Secondary cancer of the bronchi. General review apropos of 3 cases]. / Les cancers secondaires des bronches. Revue générale à propos de trois cas.

The authors report 3 cases of endobronchial metastases of visceral carcinomas (kidney, breast, pancreas). With the aid of a review of the 144 cases found in the literature, they analyse the characteristics of this special type of secondary neoplasm and their diagnostic, physiopathological and therapeutic aspects.

Pharmacokinetics of vinorelbine in man.

The pharmacokinetics of vinorelbine has been investigated by a new HPLC method in 8 cancer patients receiving 8 weekly doses (30 mg.m-2) administered by brief infusion (15 min). The plasma concentration-time curves showed a tri-exponential decay with a long terminal half-life (44.7 h) and a high volume of distribution (Vz = 75.61.kg-1). The concentrations after the 8th infusion were significantly lower than after the 1st infusion, but without significant modification of CL (1.28 l.h-1.kg-1) or AUC (0.80 mg.l-1.h). The pharmacokinetic parameters exhibited wide interindividual variations. The results are consistent with those of previous RIA studies, although the HPLC method appears to be more specific and more precise.

Solid-state and high-resolution liquid 119Sn NMR spectroscopy of some monomeric, two-coordinate low-valent tin compounds: very large chemical shift anisotropies.

High-resolution liquid- and solid-state 119Sn NMR spectroscopy was used to study the bonding environment in the series of monomeric, two-coordinate Sn(II) compounds of formula Sn(X)C6H3-2,6-Trip2 (X = Cl, Cr(eta 5-C5H5)(CO)3, t-Bu, Sn(Me)2C6H3-2,6-Trip2; Trip = C6H2-2,4,6-i-Pr3). The trends in the principal components of the chemical shift tensor extracted from the solid-state NMR data were consistent with the structures determined by X-ray crystallography. Furthermore, the spectra for the first three compounds displayed the largest 119Sn NMR chemical shift anisotropies (up to 3798 ppm) of any tin compound for which data are currently available. Relaxation time based calculations for the dimetallic compound 2,6-Trip2H3C6Sn-Sn(Me)2C6H3-2,6-Trip2 suggests that the chemical shift anisotropy for the two-coordinate tin center may be as much as ca. 7098 ppm, which is as broad as the 1 MHz bandwidth of the NMR spectrometer.