Room temperature CW operation ofGa0.3In0.7As/GaInAsP/InP strained MQW lasers withwire active region

A room temperature CW operation of Ga_0.3In_0.7As/GaInAsP/InP GRINSCH compressive strained MQW lasers with 30~60 nm wide wire active region was achieved. This device was fabricated by two-step LP-OMVPE growths on p-type InP substrate and wet chemical etching. Threshold current as low as 53 mA ( L=910 μm, J_th=2.9 kA/cm²) was obtained at RT-CW condition. The spontaneous emission peak and the lasing wavelength of strained MQW wire lasers exhibited approximately 20-meV blue shift from those of MQW film lasers cut out from the same wafer     

Fine-Grained Silicon Nitride Ceramics Prepared from β-Powder

Fine β-powder with an average particle size of 0.28 μm was prepared by grinding and centrifugal sedimentation of sub-micrometer β-powder. Fine- and uniform-grained ceramics were fabricated from the powder by hot pressing. The average grain size of the ceramic was 0.21 μm. It was shown that this kind of microstructure was desirable for the matrix of in situ composite. It was also shown that the ceramics could be superplastically deformed at a temperature as low as 1500°C.     

Association of alpha1-antichymotrypsin polymorphism with cerebral amyloid angiopathy

Hemodialysis permits a long term survival to patients with End Stage Renal Disease (E.S.R.D.). However the patients ongoing hemodialysis presented a immunodeficiency and a important modification of drugs biodisponibility. Tuberculosis is an endemic disease in our countries. Extrapulmonary tuberculosis is reported from these two cases among 13 patients treated in C.H.U.A. Le Dantec hemodialysis center. Clinical symptoms are not specific bacteria is not found. Diagnosis is obtained by a bundle of arguments. Antituberculosis treatment need to be adjusted in this field. Even if Rifampicine can be administrated at normal dose. The others drugs must be adapted on their clearance and the underlying disease. The two patients presented psychiatrical symptoms motivating a reduction of isoniazide dose witch threshold toxicity is lowered by renal failure state. These observations must increase watchfulness on nephrologist of undeveloping countries, confronted with tuberculosis renewed out break.     

Electric-field-induced refractive index variation in quantum-well structure

The refractive index variation in a quantum-well structure by an electric field is given theoretically. The calculated variation is ?1% for an applied field of 3.1×105 V/cm in a 300 ?-thick GaInAsP/InP single quantum well, which is about 39 times larger than the bulk value. A semiconductor quantum-well structure is found theoretically to be a new material with a larger electro-optic coefficient. Application to a new optical switching device is also suggested.     

Synthesis of Highly Luminescent SnO2 Nanocrystals: Analysis of their Defect‐Related Photoluminescence Using Polyoxometalates as Quenchers

Colloidal semiconductor nanocrystals (NCs), called quantum dots (QDs), have been intensively studied because of their excellent photoluminescence (PL) quantum yields. However, commercial QDs such as CdSe and InP contain toxic or expensive rare elements, limiting their sustainable use. This study focuses on nontoxic, stable, and cheap tin oxides, and synthesized luminescent SnO₂ NCs of ≈2 nm in size by a heating‐up method. Tin precursors and diols in a high‐boiling point solvent with oleylamine as the surfactant are heated at 240 °C. SnO₂ NCs show defect‐related photoluminescence at 400–460 nm by excitation at 370 nm, achieving a high quantum yield of more than 60%. The PL intensity is stable even when the NCs are stored in atmospheric air at room temperature for over 1 year. The defect‐related emissions of the SnO₂ NCs are studied using polyoxometalates (POMs) as the PL quencher. POMs efficiently quench the PL emissions by extracting excited electrons from the conduction band and shallow surface defects. The results reveal that PL emissions from SnO₂ NCs are associated with radiative charge recombination via shallow defect levels on the surface and in the bulk, demonstrating the effectiveness of the PL quenching technique using POMs in studying the PL emission mechanism in QDs.     

Effect of Blocking and Superconducting Layer Doping on the Superconductivity and Magnetic Properties of Polycrystalline Sr<Subscript>2</Subscript>CaCu<Subscript>2</Subscript>O<Subscript>6</Subscript>

The possible difference in the properties upon doping the Sr₂CaCu₂O₆ superconducting or blocking layers with Fe and Eu respectively was investigated in this work. The homogeneous Sr_2?yEu_yCaCu₂O_6+δ and Sr₂CaCu_2?xFe_xO_6+δ (y = 0, 0.1, 0.5, x = 0, 0.05) compounds were produced by a high-pressure synthesis route. Judging by the magnetic susceptibility measurements, all samples exhibit a superconductivity transition and the Eu/Fe concentration dependencies on the diamagnetic moment and average T_c have been constructed using the experimental data. As a result, an unusual behavior of the T_c value was observed for the samples with doped Eu: a fivefold reduction in the europium concentration in the sample does not give a noticeable effect on the transition temperature value while the diamagnetic signal becomes more stronger. Complex superconducting dome was found for Eu-doped material: 0.1 ≤ y ≤ 0.5 region T_c vs. concentration data were approximated by inverted parabola-like curve with a maximum at y = 0.3. Difference in properties of the Eu and Fe-doped samples was also found in the behavior of the hysteresis loops showed the opposite orientations.