RESUMEN
Uniparental disomy (UPD) is when all or part of the homologous chromosomes are inherited from only one of the two parents. Currently, UPD has been reported to occur for almost all chromosomes. In this study, we report two cases of UPD for chromosome 2 (UPD2) encountered during prenatal diagnosis. The ultrasound findings of the fetuses from two unrelated families showed intrauterine growth restriction. The karyotype analyses were normal. The two fetuses both had complete paternal chromosome 2 uniparental disomy detected by whole-exome sequencing, but their clinical outcomes were significantly different, with fetal arrest in case 1 and birth in case 2. In this report, we analyzed and discussed the phenotypes of the fetuses in these two cases and reviewed the literature on UPD2.
RESUMEN
Surface-enhanced Raman scattering (SERS) spectroscopy aims to augment the relatively weak molecular vibrations based on electromagnetic enhancement (EE) and chemical enhancement (CE) mechanisms, and offers a potential way for material identification, even up to the single-molecule level, under atmospheric conditions. We have subtly combined the advantages of EE and CE, and propose new MXene (Ti3C2TX) nano-sheet/Au nanostructure architectures to break through the limitations of the Raman detection with long-time stability. The MXene nanosheets with excellent biocompatibility can effectively prevent structural distortion from the interaction with the Au NSs, and can also guarantee a high enhancement effect owing to the spatially extended electromagnetic field distribution and electron injection into the molecules. The self-assembled Au nanostructures are aggregated based on the Volmer-Weber growth model, and the electromagnetic field distribution radically evolves depending on the morphologies of the resultant Au nanostructures, leading to a drastic compensation for the limited EE of the MXene nano-sheets. Consequently, the intensified Raman vibrational signals of R6G molecules lead to a high enhancement factor of 2.9 × 107, even at an ultra-low concentration of 10-10 M. Similarly, the Raman signals of the methylene blue (MB) and crystal violet (CV) molecules can also be detected at low concentrations below 10-8 M, manifesting universal applications of the MXene/Au architectures for ultra-sensitive molecular detection under atmospheric conditions.
RESUMEN
The structural, magnetic, electrical and dielectric properties of an Ir-based double perovskite compound, La2CoIrO6, have been investigated. The sample undergoes a paramagnetic-ferromagnetic transition at TC, followed by a reentrant spin-glass transition at lower temperatures. The reentrant spin glass state in La2CoIrO6 is associated with the competitions of the antiferromagnetic coupling between Ir4+ and Co2+ ions and the ferromagnetic clusters. La2CoIrO6 shows a semiconducting transport behavior in the temperature range 65 to 360 K and the transport behavior can be well described by the three-dimensional Mott variable range hopping conduction mechanism. Moreover, a strong frequency dependence of dielectric constant behavior for La2CoIrO6 is observed and the dielectric relaxation can be ascribed to the electron hopping between different transition metal ions. In addition, the isothermal magnetic field dependent dielectric constant measurements show that a clear magnetodielectric coupling effect exists in La2CoIrO6 at low temperatures.