Structural and Optical Properties of Diluted Magnetic Ga1−xMnxAs–AlAs Quantum Wells Grown on High-Index GaAs Planes

We report on the structural and optical properties of Ga₁₋ᵪ Mn ᵪ As-AlAs quantum wells (QWs) with χ=0.1% grown by molecular beam epitaxy (MBE) on semi-insulating GaAs substrates with orientations (100), (110), (311)B and (411)B. Atomic force microscopy (AFM), X-ray diffraction (XRD) and photoluminescence (PL) techniques were used to investigate these QWs. AFM results have evidenced the formation of Mn-induced islands, which are randomly distributed on the surface. These islands tend to segregate for samples grown on (110) and (411)B planes, while no clear segregation was observed for samples grown on (100) and (311)B orientations. Results show that the PL line width increases with Mn segregation. XRD measurements were used to determine 2θ,d and cell parameters

Comparative Study of rK39 Leishmania Antigen for Serodiagnosis of Visceral Leishmaniasis: Systematic Review with Meta-Analysis

Visceral Leishmaniasis (VL) is a neglected tropical disease for which serodiagnostic tests are available, but not yet widely implemented in rural areas. The rK39 recombinant protein is derived from a kinesin-like protein of parasites belonging to the Leishmania donovani complex, and has been used in the last two decades for the serodiagnosis of VL. We present here a systematic review and meta-analysis of studies evaluating serologic assays (rK39 strip-test, rK39 ELISA, Direct Agglutination Test [DAT], Indirect Immunofluorescence test [IFAT] and ELISA with a promastigote antigen preparation [p-ELISA]) to diagnose VL to determine the accuracy of rK39 antigen in comparison to the use of other antigen preparations. Fourteen papers fulfilled the inclusion and exclusion selection criteria. The summarized sensitivity for the rK39-ELISA was 92% followed by IFAT 88% and p-ELISA 87%. The summarized specificity for the three diagnostic tests was 81%, 90%, and 77%. Studies comparing the rK39 strip test with DAT found a similar sensitivity (94%) and specificity (89%). However, the rK39 strip test was more specific than the IFAT and p-ELISA. In conclusion, we found the rK39 protein used either in a strip test or in an ELISA is a good choice for the serodiagnosis of VL

Immunochromatographic rK39 strip test in the serodiagnosis of visceral leishmaniasis in Tunisia

International audienceThe performance of the rK39 strip test in the diagnosis of Tunisian visceral leishmaniasis (VL) was evaluated and compared with that of immunofluorescent antibody test (IFAT). A total of 929 sera, including 574 from VL patients, 54 from cutaneous leishmaniasis (CL) patients, 42 from patients with other protozoan diseases, 152 from patients with non-parasitic diseases and 107 from healthy controls, were used in the study. The sensitivity and specificity of the rK39 strip test were 87.1 and 94.4%, respectively. Sixteen CL sera showed positive results, suggesting that the rK39 strip test is not restricted to Leishmania donovani complex detection. IFAT was comparatively more sensitive (98.9%) but slightly less specific (90.7%). Despite cross-reactivity shown by CL sera, the rK39 strip test can be recommended for the routine diagnosis of VL in Tunisia, as VL and CL are distinct clinical. entities. (C) 2008 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved

Electrical and optical characterizations of InAs/GaAs quantum dot solar cells

© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. The electrical and optical characterizations of InAs/GaAs quantum dot solar cells (QDSCs) were investigated by frequency dependent capacitance–voltage (C–V) measurements and photoreflectance (PR) spectroscopy. The C–V results confirmed that the frequency dependent junction capacitance (C j ) of QDSC is sensitive to the carrier exhaustion process through trapping and recapturing in the strain-induced defects and QD states caused by the interface strain between InAs and GaAs materials. As a result, at a low frequency (≤ 200 kHz), the C j of the QDSCs decreased with increasing InAs deposition thickness (θ), leading to the decrease in carrier concentration (N d ) of the n-GaAs absorber layer due to the carrier losses processes caused by the trapping and re-capturing in the defects and the relatively large QDs. At θ ≤ 2.0 ML, the p-n junction electric field strength (F pn ) of the QDSCs which was evaluated by PR spectra decreased with increasing excitation photon intensity (I ex ) due to the typical field screening effect in the SC structure. On the other hand, the F pn of QDSCs with θ ≥ 2.5 ML approached a constant value with a relatively high I ex , which suggests that the decrease in photo-generated carriers in the QDSC was caused by the re-capturing and trapping process