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Pure magnesium (Mg) develops a strong basal texture after conventional processing of hot rolling or extrusion. Consequently, it exhibits anisotropic mechanical properties and is difficult to form at room temperature. Adding appropriate alloying elements can weaken the basal texture or even change it, but the improvement in formability and mechanical properties is still far from expectations. Over the past 20 years, considerable efforts have been made and significant progress has been made on wrought Mg alloys at the fundamental and technological levels. At the fundamental level, textures formed in sheets and extrusions of different alloy compositions and produced under different strain paths or thermomechanical processing conditions are relatively well established, with the assistance of the advanced characterization technique of electron backscatter diffraction. At the technological level, room temperature formability of sheet has been significantly improved, and tension–compression yield asymmetry of extrusion is also remarkably reduced or eliminated. This paper starts with an overview of dislocations, stacking faults and twins, and deformation of single crystals of pure Mg along different orientations and under different loading conditions, followed by a review of microstructure (texture and grain size) and deformation of polycrystalline pure Mg with different textures, grain sizes, and loading conditions. With this information as a base, texture, grain size, and deformation of polycrystalline Mg alloy sheets and extrusions produced under different processing conditions are systematically examined and compared. Remaining and emerging scientific and technology issues are then highlighted and discussed in the context of texture and grain size. The need for better-resolution diffraction and spectroscopy techniques is also discussed in the relationship between texture change and grain boundary solute segregation.

The presence of a di-unsaturated highly branched isoprenoid (HBI) lipid biomarker (diene II) in Southern Ocean sediments has previously been proposed as a proxy measure of palaeo Antarctic sea ice. Here we show that a source of diene II is the sympagic diatom Berkeleya adeliensis Medlin. Furthermore, the propensity for B. adeliensis to flourish in platelet ice is reflected by an offshore downward gradient in diene II concentration in >100 surface sediments from Antarctic coastal and near-coastal environments. Since platelet ice formation is strongly associated with super-cooled freshwater inflow, we further hypothesize that sedimentary diene II provides a potentially sensitive proxy indicator of landfast sea ice influenced by meltwater discharge from nearby glaciers and ice shelves, and re-examination of some previous diene II downcore records supports this hypothesis. The term IPSO 25 —Ice Proxy for the Southern Ocean with 25 carbon atoms—is proposed as a proxy name for diene II. The sedimentary presence of the diatom lipid diene II (hereafter IPSO 25 ) has been proposed as a proxy for palaeo Antarctic sea ice. Here, the authors identify a source of IPSO 25 and hypothesize that its sedimentary distribution may provide proxy evidence of landfast ice influenced by freshwater discharge.

We use five years (2009–2013) of multiwavelength Raman lidar measurements at Gwangju, South Korea (35.10° N, 126.53° E) for the identification of changes of optical properties of East Asian dust depending on its transport path over China. Profiles of backscatter and extinction coefficients, lidar ratios, and backscatter-related Ångström exponents (wavelength pair 355/532 nm) were measured at Gwangju. Linear particle depolarization ratios were used to identify East Asian dust layers. We used backward trajectory modeling to identify the pathway and the vertical position of dust-laden air masses over China during long-range transport. Most cases of Asian dust events can be described by the emission of dust in desert areas and subsequent transport over highly polluted regions of China. The Asian dust plumes could be categorized into two classes according to the height above ground at which these plumes were transported: (case I) the dust layers passed over China at high altitude levels (> 3 km) until arrival over Gwangju, and (case II) the Asian dust layers were transported near the surface and within the lower troposphere (< 3 km) over industrialized areas before they arrived over Gwangju. We find that the optical characteristics of these mixed Asian dust layers over Gwangju differ depending on their vertical position above ground over China and the change of height above ground during transport. The mean linear particle depolarization ratio was 0.21 ± 0.06 (at 532 nm), the mean lidar ratios were 52 ± 7 sr at 355 nm and 53 ± 8 sr at 532 nm, and the mean Ångström exponent was 0.74 ± 0.31 for case I. In contrast, plumes transported at lower altitudes (case II) showed low depolarization ratios (0.13 ± 0.04 at 532 nm), and higher lidar ratio (63 ± 9 sr at 355 nm and 62 ± 8 sr at 532 nm) and Ångström exponents (0.98 ± 0.51). These numbers show that the optical characteristics of mixed Asian plumes are more similar to optical characteristics of urban pollution. We find a decrease of the linear depolarization ratio of the mixed dust/pollution plume depending on transport time if the pollution layer traveled over China at low heights, i.e., below approximately 3 km above ground. In contrast, we do not find such a trend if the dust plumes traveled at heights above 3 km over China. We need a longer time series of lidar measurements in order to determine in a quantitative way the change of optical properties of dust with transport time.

Ghost imaging is demonstrated using beams of correlated pairs of ultracold helium atoms, rather than photons, yielding a reconstructed image with submillimetre resolution. Ghost imaging with massive particles Ghost imaging achieves a feat that sounds impossible: the reconstruction of an image of an object using a beam of light that has never interacted with the object. The trick that makes it possible involves the use of two beams of correlated photons. One beam passes through the object to a bucket (single-pixel) detector, while the spatial profile of the second beam is measured by a high-resolution (multi-pixel) detector; but, this second beam never interacts with the object. Until now ghost imaging has been achieved only with photons, but here Andrew Truscott and colleagues report a technique for producing ghost images with massive particles—specifically, with ultracold helium atoms. Substituting photons in quantum mechanical experiments for massive particles could shed light on fundamental questions such as the quantum-to-classical transition. In addition, this methodology may facilitate applications such as real-time control of atom lithography while imaging the deposition remotely via the ghost imaging technique. Ghost imaging is a counter-intuitive phenomenon—first realized in quantum optics 1 , 2 —that enables the image of a two-dimensional object (mask) to be reconstructed using the spatio-temporal properties of a beam of particles with which it never interacts. Typically, two beams of correlated photons are used: one passes through the mask to a single-pixel (bucket) detector while the spatial profile of the other is measured by a high-resolution (multi-pixel) detector. The second beam never interacts with the mask. Neither detector can reconstruct the mask independently, but temporal cross-correlation between the two beams can be used to recover a ‘ghost’ image. Here we report the realization of ghost imaging using massive particles instead of photons. In our experiment, the two beams are formed by correlated pairs of ultracold, metastable helium atoms 3 , which originate from s -wave scattering of two colliding Bose–Einstein condensates 4 , 5 . We use higher-order Kapitza–Dirac scattering 6 , 7 , 8 to generate a large number of correlated atom pairs, enabling the creation of a clear ghost image with submillimetre resolution. Future extensions of our technique could lead to the realization of ghost interference 9 , and enable tests of Einstein–Podolsky–Rosen entanglement 9 and Bell’s inequalities 10 with atoms.

While there are persistent calls for developing more marine protected areas (MPAs) for Asian horseshoe crab conservation in response to population declines in Asia–Pacific region, most existing horseshoe crab MPAs were designated without prior comprehensive population assessment and habitat characterization. This study collected biological and habitat information in Hong Kong, in order to identify priority sites for conservation and management of Asian horseshoe crab populations. The territory-wide surveys at 18 spawning/nursery beaches displayed a persistently low mean juvenile density from 0.16 to 2.19 ind/100 m² in 2012 and 0.08 to 1.41 ind/100 m² in 2014. These density data were within the same range of that in 2002 and 2007 (0.10–1.97 ind/100 m²), apart from a low survey return of 0.08–0.31 ind/100 m² in 2004. The current population of juvenile T. tridentatus and C. rotundicauda in Hong Kong is estimated about 2100–4300 and 2400–3000 individuals, respectively. From the 2012–2014 data, no new recruitments of 1st–3rd instar juveniles were found, as the shores were occupied mostly by 6th–9th instar juveniles of prosomal width between 23 and 45 mm, in which considerably high mortality rates were noted. The present findings of existing small and discrete juvenile populations, coupled with relatively few recruits, suggest that the status of juvenile horseshoe crabs in Hong Kong is fragile and vulnerable to local extirpation, especially if no urgent protection measures are implemented. Based on available population data and habitat characteristics, three MPAs, ranging from 5 to 7 km², are proposed, so as to conserve over 60 and 70 % of the existing juvenile populations of T. tridentatus and C. rotundicauda, respectively. The approach adopted in this study may serve as a case study for proposing other horseshoe crab MPAs in Asia, where increasing human disturbances and over-harvest are imminent.

SummaryThe population-based cohort study used the Korean National Health Insurance claims database to evaluate the effect of anti-diabetic drugs on osteoporosis. The use of DPP-IV inhibitors does not increase the risk of osteoporosis compared with the use of sulfonylureas in patients with type 2 diabetes mellitus, while a weak association was found between thiazolidinediones and increased risk of osteoporosis.PurposeThe current study aimed to evaluate the effect of dipeptidyl peptidase IV inhibitors (DPP-IVi), thiazolidinedione (TZD), and sulfonylurea (SU) on osteoporosis in patients with type 2 diabetes.MethodsA population-based cohort study was conducted in the Republic of Korea using the Korean National Health Insurance claims database. Data from 2012 to 2017 for patients of 50–99 years of age who were prescribed DPP-IVi, TZD, or SU during 2013–2015 were extracted from the database. Based on pre-defined criteria, a total of 381,404 patients were analyzed after inverse probability of treatment weighting. The association between the study drugs and osteoporosis was estimated using Cox proportional hazards models. Data of 220,166 patients who were prescribed DPP-IVi, 18,630 who were prescribed TZD, and 142,608 patients who were prescribed SU were set.ResultsIn the multivariate-adjusted analysis, the hazard ratio (HR) of osteoporosis in the DPP-IVi group was not significantly different from that of the SU group (HR: 0.97; 95% confidence interval (CI) 0.94–1.00), whereas the HR of osteoporosis in the TZD group was higher (HR: 1.13; 95% CI 1.06–1.20). In the subgroup analysis, the HRs of osteoporosis were higher with pioglitazone (HR: 1.14; 95% CI 1.06–1.23) in the TZD group and with glibenclamides (HR: 1.39; 95% CI 1.09–1.77) in the SU group, whereas drugs with lower HR in the DPP-IVi group were saxagliptin (HR: 0.93; 95% CI 0.87–0.99) and sitagliptin (HR: 0.93; 95% CI 0.89–0.97).ConclusionDPP-IV inhibitors do not increase the risk of osteoporosis compared with sulfonylureas in patients with type 2 diabetes mellitus, while a weak association was found between thiazolidinediones and increased risk of osteoporosis.

Fast radio bursts (FRBs) are flashes of unknown physical origin 1 . The majority of FRBs have been seen only once, although some are known to generate multiple flashes 2 , 3 . Many models invoke magnetically powered neutron stars (magnetars) as the source of the emission 4 , 5 . Recently, the discovery 6 of another repeater (FRB 20200120E) was announced, in the direction of the nearby galaxy M81, with four potential counterparts at other wavelengths 6 . Here we report observations that localized the FRB to a globular cluster associated with M81, where it is 2 parsecs away from the optical centre of the cluster. Globular clusters host old stellar populations, challenging FRB models that invoke young magnetars formed in a core-collapse supernova. We propose instead that FRB 20200120E originates from a highly magnetized neutron star formed either through the accretion-induced collapse of a white dwarf, or the merger of compact stars in a binary system 7 . Compact binaries are efficiently formed inside globular clusters, so a model invoking them could also be responsible for the observed bursts. The fast radio burst FRB 20200120E is shown to originate from a globular cluster in the galaxy M81, and may be a collapsed white dwarf or a merged compact binary star system.

Effect of 1 wt pct Gd addition on the microstructural evolution, mechanical properties and bio-corrosion behavior of the biodegradable Mg-4Zn alloy was studied. The average grain size of the base alloy decreased from 14.6 to 5.7 µm after Gd addition. In contrast to the base Gd-free alloy, a fiber texture with higher intensity of basal poles and lower Schmid factor was formed during the hot extrusion in the Gd-containing alloy. This was attributed to the presence of a relatively high volume fraction of un-recrystallized grains. The respective yield stress (YS) and ultimate tensile strength (UTS) values were significantly improved from 198 MPa and 301 MPa in the Mg-4Zn alloy to 241 MPa and 336 MPa in the Mg-4Zn-1Gd alloy, due to the finer grain size, second phase particles and textural hardening. Extension twins were responsible for achieving the respective high elongations of 33.9 and 20.6 pct for the base and Gd-containing alloys, during tensile loading. Electron backscattered diffraction (EBSD) analysis of the corroded surfaces indicated high pitting susceptibility of the non-basal planes and un-recrystallized grains. Despite the higher stored energy in the Gd-containing alloy due to the lower fraction of recrystallized grains, the finer grain size and the presence of Gd in the corroded layer resulted in improved biodegradability of this alloy.

The functional interpretation of genome-wide association studies (GWAS) is challenging due to the cell-type-dependent influences of genetic variants. Here, we generated comprehensive maps of expression quantitative trait loci (eQTLs) for 659 microdissected human kidney samples and identified cell-type-eQTLs by mapping interactions between cell type abundances and genotypes. By partitioning heritability using stratified linkage disequilibrium score regression to integrate GWAS with single-cell RNA sequencing and single-nucleus assay for transposase-accessible chromatin with high-throughput sequencing data, we prioritized proximal tubules for kidney function and endothelial cells and distal tubule segments for blood pressure pathogenesis. Bayesian colocalization analysis nominated more than 200 genes for kidney function and hypertension. Our study clarifies the mechanism of commonly used antihypertensive and renal-protective drugs and identifies drug repurposing opportunities for kidney disease. Cell-type-specific eQTL maps in the human kidney generated from the analysis of over 600 microdissected kidney samples, together with single-cell RNA sequencing and single-nucleus ATAC-seq, prioritize cell types influencing kidney function, hypertension and other traits.

Detailed dielectric measurements are reported for polycrystalline ( NH 4 ) 3 H( SO 4 ) 2 at temperatures 10 K < T < 100 K and frequencies 20 Hz < ν < 3 MHz. Instead of the ferroelectric phase transition expected at 63 K, a typical dipole glass transition was observed at around 60 K. The frequency dependence of the complex dielectric permeability at T < 50 K was well described by a sum of two Cole–Cole functions. One of the two relaxators provides a background contribution to the dielectric dispersion. The most probable relaxation time for the main relaxator was best fitted to the modified Arrhenius law with τ 0 = 3.5 × 10 - 13 s, E = 50 K γ , and γ = 0.37 .