Discovery of Lorentz-violating Weyl fermion semimetal state in LaAlGe materials

We report theoretical and experimental discovery of Lorentz-violating Weyl fermion semimetal type-II state in the LaAlGe class of materials. Previously type-II Weyl state was predicted in WTe2 materials which remains unrealized in surface experiments. We show theoretically and experimentally that LaAlGe class of materials are the robust platforms for the study of type-II Weyl physics.Comment: This paper reports theoretical prediction and experimental discovery together. A detailed theoretical paper describing the topology of the full family of X(Lanthanides)AlGe materials will follow. Other related papers can be found at http://physics.princeton.edu/zahidhasangroup/index_WS.htm

Middle Jurassic terrestrial environmental and floral changes linked to volcanism: Evidence from the Qinghai Tibet Plateau, China

The breakup of Pangaea and the rapid opening of the Ligurian and Central Atlantic oceans during the Middle Jurassic resulted in widespread volcanism accompanied by significant shifts in global environments, climates, and floras. Although major volcanism is a plausible driver of such global changes, linking these phenomena in the Middle Jurassic is hindered by a lack of detailed sedimentary records from which to evaluate cause and effect. Here, we link Middle Jurassic environmental, climatic, and floral changes with volcanism using records from the Dameigou section of the Qaidam Basin on the Qinghai-Tibet Plateau. High-resolution chemostratigraphic (δ13Corg patterns) and biostratigraphic (palynological fossils) data reveal three negative organic carbon isotope excursions (NCIE) at the Aalenian-Bajocian boundary, the Bajocian-Bathonian boundary, and in the middle of the Callovian, respectively. The first two NCIEs (NCIE-I and NCIE-II) were accompanied by relatively warm and humid climatic conditions and coal accumulation. In contrast, the third NCIE (NCIE-III) was accompanied by warm but dry climatic conditions, a decrease in coal accumulation, a decline in plant diversity, the significant decline in fern spore diversity and abundance, and a rapid increase in the abundance of Classopollis pollen (based on petrological, palynological, PCA, Hydrophyte/Xerophyte ratio, and nMDS data). Four sedimentary mercury anomalies (Hg/Al spikes) have temporal coincidence with the three NCIEs and climate warming events, suggesting a volcanic origin for these. We suggest that volcanism was a key driver of Middle Jurassic change, with major pulses releasing large amounts of CO2 and Hg into the atmosphere, resulting in Hg loading, NCIEs, climatic warming, and floral changes in terrestrial strata. Our multi-proxy study provides new insights into the links between volcanism and terrestrial environmental, climatic, and floral changes during the Middle Jurassic

Four volcanically driven climatic perturbations led to enhanced continental weathering during the Late Triassic Carnian Pluvial Episode

The arid climate of the Late Triassic was interrupted by a particularly humid episode known as the Carnian Pluvial Episode (CPE; ca. 234–232 million years ago). The CPE is often linked to eruptions in the Wrangellia Large Igneous Province (LIP), and is assumed to have led to global warming, enhanced weathering, water deoxygenation, and biotic changes. However, direct evidence for a temporal link between volcanic activity and chemical weathering has not yet been established due to the lack of comprehensive records across the CPE. In this study, geochemical and mineralogical analyses are applied to a lacustrine stratigraphic succession of the Jiyuan Basin (North China) that captures the CPE in high resolution. We identify four distinct pulses of enhanced continental chemical weathering characterized by elevated Chemical Index of Alteration values and kaolinite contents. These peaks in continental weathering coincide with Hg/TOC enrichments and negative organic carbon isotope excursions that mark four short (~400 kyr) but intense pulses of Wrangellia LIP volcanism. In combination with signs of increased humidity, our findings provide direct and independent evidence that Wrangellia LIP eruptions significantly altered CPE chemical weathering rates in response to global warming and wetting. The lake experienced eutrophication and water deoxygenation after each volcanic pulse but the swift recovery of carbon isotopes suggests that the system rapidly returned to conditions prior to the volcanic perturbation. Organic carbon burial facilitated by widespread dysoxic and anoxic waters, and CO2 consumption via enhanced weathering likely played crucial roles in the rapid climatic recovery after each volcanic pulse

Observation of Weyl fermions in a magnetic non-centrosymmetric crystal

Characterized by the absence of inversion symmetry, non-centrosymmetric materials are of great interest because they exhibit ferroelectricity, second harmonic generation, emergent Weyl fermions, and other fascinating phenomena. It is expected that if time-reversal symmetry is also broken, additional magneto-electric effects can emerge from the interplay between magnetism and electronic order. Here we report topological conducting properties in the non-centrosymmetric magnet PrAlGe. By photoemission spectroscopy, we observe an arc parametrizing surface-localized states---a topological arc. Using the bulk-boundary correspondence, we conclude that these arcs correspond to projected topological charges of $\pm{1}$ in the surface Brillouin zone, demonstrating the presence of magnetic Weyl quasiparticles in bulk. We further observe a large anomalous Hall response, arising from diverging bulk Berry curvature fields associated with the magnetic Weyl band structure. Our results demonstrate a topological phase with robust electronic surface states and anomalous transport in a non-centrosymmetric magnet for the first time, providing a novel material platform to study the interplay between magnetic order, band topology and transport.Comment: To appear in Nature Communications (2020

Constructing a new integrated genetic linkage map and mapping quantitative trait loci for vegetative mycelium growth rate in Lentinula edodes

The most saturated linkage map for Lentinula edodes to date was constructed based on a mono-. karyotic population of 146 single spore isolates (SSIs) using sequence-related amplified polymorphism (SRAP), target region amplification polymorphism (TRAP), insertion deletion (InDel) markers, and the mating-type loci. Five hundred and twenty-four markers were located on 13 linkage groups (LGs). The map spanned a total length of 1006.1 cM, with an average marker spacing of 2.0 cM. Quantitative trait loci (QTLs) mapping was utilized to uncover the loci regulating and controlling the vegetative mycelium growth rate on various synthetic media, and complex medium for commercial cultivation of L. edodes. Two and 13 putative QTLs, identified respectively in the monokaryotic population and two testcross dikaryotic populations, were mapped on seven different LGs. Several vegetative mycelium growth rate-related QTLs uncovered here were clustered on LG4 (Qmgr1, Qdgr1, Qdgr2 and Qdgr9) and LG6 (Qdgr3, Qdgr4 and Qdgr5), implying the presence of main genomic areas responsible for growth rate regulation and control. The QTL hotspot region on LG4 was found to be in close proximity to:the region containing the mating-type A (MAT-A) locus. Moreover, Qdgr2 on LG4 was detected on different media, contributing 8.07%-23.71% of the phenotypic variation. The present study provides essential information for QTL mapping and marker-assisted selection (MAS) in L. edodes. (C) 2014 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.The most saturated linkage map for Lentinula edodes to date was constructed based on a mono-. karyotic population of 146 single spore isolates (SSIs) using sequence-related amplified polymorphism (SRAP), target region amplification polymorphism (TRAP), insertion deletion (InDel) markers, and the mating-type loci. Five hundred and twenty-four markers were located on 13 linkage groups (LGs). The map spanned a total length of 1006.1 cM, with an average marker spacing of 2.0 cM. Quantitative trait loci (QTLs) mapping was utilized to uncover the loci regulating and controlling the vegetative mycelium growth rate on various synthetic media, and complex medium for commercial cultivation of L. edodes. Two and 13 putative QTLs, identified respectively in the monokaryotic population and two testcross dikaryotic populations, were mapped on seven different LGs. Several vegetative mycelium growth rate-related QTLs uncovered here were clustered on LG4 (Qmgr1, Qdgr1, Qdgr2 and Qdgr9) and LG6 (Qdgr3, Qdgr4 and Qdgr5), implying the presence of main genomic areas responsible for growth rate regulation and control. The QTL hotspot region on LG4 was found to be in close proximity to:the region containing the mating-type A (MAT-A) locus. Moreover, Qdgr2 on LG4 was detected on different media, contributing 8.07%-23.71% of the phenotypic variation. The present study provides essential information for QTL mapping and marker-assisted selection (MAS) in L. edodes. (C) 2014 The British Mycological Society. Published by Elsevier Ltd. All rights reserved

Effects of soybean isoflavone aglycone on osteoporosis in ovariectomized rats

Postmenopausal osteoporosis is one of the most common metabolic diseases in old women, and supplementing estrogen through bioactive substances is one of the important ways to improve menopausal syndrome. Some studies have confirmed that soybean isoflavone has estrogenic activity, and the main active component of soybean isoflavones is isoflavone aglycones. However, few studies have investigated the improvement effect of high-purity soy isoflavone aglycones on postmenopausal osteoporosis. Thus, the effect of different doses of high-purity soybeans isoflavone aglycone on the ovariectomized female osteoporosis rat model was evaluated by oral gavage. The rats were divided into seven experimental groups including SHAM, OVX, EE, SIHP, AFDP-L, AFDP-M, and AFDP-H, which was administered for 60 days from 30 days after ovariectomy. We collected blood from the abdominal aorta of rats on the 30th, 60th, and 90th days respectively, analyzed its serum biochemistry, and took out the femur for micro-CT imaging and bone microstructure parameter analysis. Results showed that the intervention effect of AFDP-H group on osteoporosis rats at 60 and 90 days was similar to that of EE group, and superior to the OVX group, SIHP group, AFDP-L group, AFDP-M group. The AFDP-H group inhibited the decrease in serum bone markers, bone density, trabeculae quantity, trabeculae thickness, and bone volume fraction, and increased the trabecular separation caused by ovariectomy, thereby significantly improving bone microstructure. It also prevented continuous weight gain and increased cholesterol levels in female rats. This study provided theoretical to application of soybean isoflavone aglycone in the intervention of osteoporosis. and confirmed that could replace chemical synthetic estrogen drugs

The importance of NOx control for peak ozone mitigation based on a sensitivity study using CMAQ‐HDDM‐3D model during a typical episode over the Yangtze River delta region, China.

In recent years, ground-level ozone (O3) has been one of the main pollutants hindering air quality compliance in China's large city-clusters including the Yangtze River Delta (YRD) region. In this work, we utilized the process analysis (PA) and the higher-order decoupled direct method (HDDM-3D) tools embedded in the Community Multiscale Air Quality model (CMAQ) to characterize O3 formation and sensitivities to precursors during a typical O3 pollution episode over the YRD region in July 2018. Results indicate that gas-phase chemistry contributed dominantly to the ground-level O3 although a significant proportion was chemically produced at the middle and upper boundary layer before reaching the surface via diffusion process. Further analysis of the chemical pathways of O3 and Ox formation provided deep insights into the sensitivities of O3 to its precursors that were consistent with the HDDM results. The first-order sensitivities of O3 to anthropogenic volatile organic compounds (AVOC) were mainly positive but small, and temporal variations were negligible compared with those to NOx. During the peak O3 time in the afternoon, the first- and second-order sensitivities of O3 to NOx were significantly positive and negative, respectively, suggesting a convex response of O3 to NOx over most areas including Shanghai, Hangzhou, Nanjing and Hefei. These findings further highlighted an accelerated decrease in ground-level O3 in the afternoon corresponding to continuous decrease of NOx emissions in the afternoon. Therefore, over the YRD region including its metropolises, NOx emission reductions will be more important in reducing the afternoon peak O3 concentration compared with the effect of VOC emission control alone