InGaAs quantum dots-in-a-well solar cells with anti-reflection coating

To improve the performance of self-assembled InGaAs quantum dots (QDs) solar cells, we introduce a 2-nm In0.1Ga0.9As quantum well underneath each In0.75Ga0.25As QDs layer to form an InGaAs quantum dots-in-a-well (DWell) structure. The coupled DWell solar cell consists of nine DWells spacing by GaAs layers. We change the GaAs spacer thickness to optimize the photovoltaic performance. The solar cell of 15-nm GaAs spacer shows the best results, including the open-circuit voltage (VOC) = 0.67 V, the short-circuit current density (JSC) = 17.4 mA/cm2, and the power conversion efficiency (η) = 8.7%, compared to the coupled InGaAs QDs counterpart of VOC = 0.59 V, JSC = 18.6 mA/cm2, and (η) = 8.0%. The enhancement of VOC for the DWell solar cell is attributed to the lower dark saturation current, which is caused by stronger carrier confinement and lower strain-induced defects in the active region. The DWell solar cell is further improved by Al2O3/HfO2 anti-reflection coating, and reaches η = 11.8% as JSC increases to 23.5 mA/cm2

Evaluation of stool microbiota signatures in two cohorts of Asian (Singapore and Indonesia) newborns at risk of atopy

10.1186/1471-2180-11-193BMC Microbiology1

A comparison of intrauterine haemopoietic cell transplantation and lentiviral gene transfer for the correction of severe β-thalassaemia in a HbbTh3/+ murine model

Major haemoglobinopathies place tremendous strain on global resources. Intrauterine haemopoietic cell (IUHCT) and gene (IUGT) therapies can potentially reduce perinatal morbidities with greater efficacy than postnatal therapy alone. We performed both procedures in the thalassaemic HbbTh3/+ murine model. Intraperitoneal delivery of coisogenic cells at E13-14 produced dose-dependent chimerism. High-dose adult bone marrow (BM) cells maintained 0.2-3.1% chimerism over ~24 weeks and treated heterozygotes demonstrated higher chimerism than wild-type pups (1.6 vs. 0.7%). Fetal liver cells produced higher chimerism compared to adult BM when transplanted at the same doses, maintaining 1.8-2.4% chimerism over ~32 weeks. We boosted transplanted mice postnatally with adult BM cells following busulfan conditioning. Engraftment was maintained at >1% only in recipients which were chimeric prior to boosting. IUHCT-treated non-chimeras and non-IUHCT mice showed micro- or no chimerism. Additional fludarabine treatment produced higher chimerism than busulfan alone. Engraftment was more effective following higher starting chimerism prior to boosting and in heterozygotes. Chimeric heterozygotes expressed 2.2-15.1% donor cells with eventual decline at 24 weeks (vs. <1% in non-chimeras) and demonstrated improved haematological indices and smaller spleens compared to untreated heterozygotes. Intravenous delivery of GLOBE lentiviral-vector expressing HBB (human β-globin) resulted in vector concentration of 0.001-0.6 copies/cell. Most haematological indices were higher in treated than untreated heterozygotes including haemoglobin and mean corpuscular volume, though still lower than in wild-types. Thus both direct IUGT and IUHCT strategies can be used to achieve haematological improvement but require further dose optimisation. IUHCT will be useful combined with postnatal transplantation to further enhance engraftment