1,175 research outputs found
(Sr3La2O5)(Zn1-xMnx)2As2: A Bulk Form Diluted Magnetic Semiconductor isostructural to the "32522" Fe-based Superconductors
A new diluted magnetic semiconductor system, (Sr3La2O5)(Zn1-xMnx)2As2, has
been synthesized and characterized. 10% Mn substitution for Zn in bulk form
(Sr3La2O5)Zn2As2 results in a ferromagnetic ordering below Curie temperature,
TC ~ 40 K. (Sr3La2O5)(Zn1-xMnx)2As2 has a layered crystal structure identical
to that of 32522-type Fe based superconductors, and represents the fifth DMS
family that has a direct counterpart among the FeAs high temperature
superconductor families.Comment: Accepted for publication in EP
Occupied and unoccupied electronic structure of Na doped MoS2(0001)
The influence of sodium on the band structure of MoS2(0001) and the comparison of the experimental band dispersion with density functional theory show excellent agreement for the occupied states (angle-resolved photoemission) and qualitative agreement for the unoccupied states (inverse photoemission spectroscopy). Na-adsorption leads to charge transfer to the MoS2 surface causing an effect similar to n-type doping of a semiconductor. The MoS2 occupied valence band structure shifts rigidly to greater binding with little change in the occupied state dispersion. Likewise, the unoccupied states shift downward, approaching the Fermi level, yet the amount of the shift for the unoccupied states is greater than that of the occupied states, effectively causing a narrowing of the MoS2 bandgap
Artificial intelligence - based ultrasound elastography for disease evaluation - a narrative review
Ultrasound elastography (USE) provides complementary information of tissue stiffness and elasticity to conventional ultrasound imaging. It is noninvasive and free of radiation, and has become a valuable tool to improve diagnostic performance with conventional ultrasound imaging. However, the diagnostic accuracy will be reduced due to high operator-dependence and intra- and inter-observer variability in visual observations of radiologists. Artificial intelligence (AI) has great potential to perform automatic medical image analysis tasks to provide a more objective, accurate and intelligent diagnosis. More recently, the enhanced diagnostic performance of AI applied to USE have been demonstrated for various disease evaluations. This review provides an overview of the basic concepts of USE and AI techniques for clinical radiologists and then introduces the applications of AI in USE imaging that focus on the following anatomical sites: liver, breast, thyroid and other organs for lesion detection and segmentation, machine learning (ML) - assisted classification and prognosis prediction. In addition, the existing challenges and future trends of AI in USE are also discussed
Exploration of signals of positive selection derived from genotype-based human genome scans using re-sequencing data.
We have investigated whether regions of the genome showing signs of positive selection in scans based on haplotype structure also show evidence of positive selection when sequence-based tests are applied, whether the target of selection can be localized more precisely, and whether such extra evidence can lead to increased biological insights. We used two tools: simulations under neutrality or selection, and experimental investigation of two regions identified by the HapMap2 project as putatively selected in human populations. Simulations suggested that neutral and selected regions should be readily distinguished and that it should be possible to localize the selected variant to within 40 kb at least half of the time. Re-sequencing of two ~300 kb regions (chr4:158Mb and chr10:22Mb) lacking known targets of selection in HapMap CHB individuals provided strong evidence for positive selection within each and suggested the micro-RNA gene hsa-miR-548c as the best candidate target in one region, and changes in regulation of the sperm protein gene SPAG6 in the other
Tlr9 deficiency in B cells leads to obesity by promoting inflammation and gut dysbiosis
Toll-like receptor 9 (TLR9) recognizes bacterial, viral and self DNA and play an important role in immunity and inflammation. However, the role of TLR9 in obesity is less well-studied. Here, we generate B-cell-specific Tlr9-deficient (Tlr9fl/fl/Cd19Cre+/-, KO) B6 mice and model obesity using a high-fat diet. Compared with control mice, B-cell-specific-Tlr9-deficient mice exhibited increased fat tissue inflammation, weight gain, and impaired glucose and insulin tolerance. Furthermore, the frequencies of IL-10-producing-B cells and marginal zone B cells were reduced, and those of follicular and germinal center B cells were increased. This was associated with increased frequencies of IFNγ-producing-T cells and increased follicular helper cells. In addition, gut microbiota from the KO mice induced a pro-inflammatory state leading to immunological and metabolic dysregulation when transferred to germ-free mice. Using 16 S rRNA gene sequencing, we identify altered gut microbial communities including reduced Lachnospiraceae, which may play a role in altered metabolism in KO mice. We identify an important network involving Tlr9, Irf4 and Il-10 interconnecting metabolic homeostasis, with the function of B and T cells, and gut microbiota in obesity
Soil contamination in nearby natural areas mirrors that in urban greenspaces worldwide
Soil contamination is one of the main threats to ecosystem health and sustainability. Yet little is known about the extent to which soil contaminants differ between urban greenspaces and natural ecosystems. Here we show that urban greenspaces and adjacent natural areas (i.e., natural/semi-natural ecosystems) shared similar levels of multiple soil contaminants (metal(loid)s, pesticides, microplastics, and antibiotic resistance genes) across the globe. We reveal that human influence explained many forms of soil contamination worldwide. Socio-economic factors were integral to explaining the occurrence of soil contaminants worldwide. We further show that increased levels of multiple soil contaminants were linked with changes in microbial traits including genes associated with environmental stress resistance, nutrient cycling, and pathogenesis. Taken together, our work demonstrates that human-driven soil contamination in nearby natural areas mirrors that in urban greenspaces globally, and highlights that soil contaminants have the potential to cause dire consequences for ecosystem sustainability and human wellbeing
Unearthing the soil-borne microbiome of land plants
Plant–soil biodiversity interactions are fundamental for the functioning of terrestrial
ecosystems. Yet, the existence of a set of globally distributed topsoil microbial and small
invertebrate organisms consistently associated with land plants (i.e., their consistent soil-borne
microbiome), together with the environmental preferences and functional capabilities
of these organisms, remains unknown. We conducted a standardized field survey
under 150 species of land plants, including 58 species of bryophytes and 92 of vascular
plants, across 124 locations from all continents. We found that, despite the immense biodiversity
of soil organisms, the land plants evaluated only shared a small fraction (less than
1%) of all microbial and invertebrate taxa that were present across contrasting climatic
and soil conditions and vegetation types. These consistent taxa were dominated by generalist
decomposers and phagotrophs and their presence was positively correlated with the
abundance of functional genes linked to mineralization. Finally, we showed that crossing
environmental thresholds in aridity (aridity index of 0.65, i.e., the transition from mesic to
dry ecosystems), soil pH (5.5; i.e., the transition from acidic to strongly acidic soils), and
carbon (less than 2%, the lower limit of fertile soils) can result in drastic disruptions in the
associations between land plants and soil organisms, with potential implications for the
delivery of soil ecosystem processes under ongoing global environmental change
Lithium, an anti-psychotic drug, greatly enhances the generation of induced pluripotent stem cells
Somatic cells can be reprogrammed into induced pluripotent stem cells (iPSCs) by defined factors. The low efficiency of reprogramming and genomic integration of oncogenes and viral vectors limited the potential application of iPSCs. Here we report that Lithium (Li), a drug used to treat mood disorders, greatly enhances iPSC generation from both mouse embryonic fibroblast and human umbilical vein endothelial cells. Li facilitates iPSC generation with one (Oct4) or two factors (OS or OK). The effect of Li on promoting reprogramming only partially depends on its major target GSK3β. Unlike other GSK3β inhibitors, Li not only increases the expression of Nanog, but also enhances the transcriptional activity of Nanog. We also found that Li exerts its effect by promoting epigenetic modifications via downregulation of LSD1, a H3K4-specific histone demethylase. Knocking down LSD1 partially mimics Li's effect in enhancing reprogramming. Our results not only provide a straightforward method to improve the iPSC generation efficiency, but also identified a histone demethylase as a critical modulator for somatic cell reprogramming
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