The precipitates inside deformation twins may block the dislocation motion and consequently affect the mechanical property of materials. Herein, at the atomic level, we directly visualize that the ...basal dislocation slips shear the twinned stacking faults (TSFs) within the deformation twins in an Mg–Zn–Y alloy containing long-period stacking ordered (LPSO) structures. The TSFs, enriched with solute atoms, could be considered as precipitates inside deformation twins. They are sheared by a single step or multiple shearing steps on the basal plane. The microstructural fingerprints, i.e., the width of basal shearing steps, enable a quantitative assessment of the local and total plastic shear strain due to the basal dislocation within the deformation twins. The TSFs can block dislocation slip, while the dislocation shearing induces large lattice distortion and even solute atoms redistribution at local intersection. The TSFs-dislocation interaction is expected to lower the basal dislocation motion and resultantly modulate the mechanical properties of magnesium alloys. These results may offer a novel strategy for strengthening and toughening magnesium alloys via tailoring the shearable precipitates.
Abstract
The fast transitions between different types of quasi-periodic oscillations (QPOs) are generally observed in black hole transient sources (BHTs). We present a detailed study of the timing ...and spectral properties of the transitions of type-B QPOs in MAXI J1348–630, observed by Insight-HXMT. The fractional rms variability–energy relationship and energy spectra reveal that type-B QPOs probably originate from jet precession. Compared to a weak power-law dominated power spectrum, when type-B QPOs are present, the corresponding energy spectrum shows an increase in the Comptonization component and the need for the
xillverCp
component, and a slight increase in the height of the corona when using the
relxilllp
model. Therefore, we suggest that a coupled inner disk-jet region is responsible for the observed type-B QPO transitions. The timescale for the appearance/disappearance of type-B QPOs is either long or short (seconds), which may indicate instability of the disk-jet structure. For these phenomena, we hypothesize that the Bardeen–Petterson effect causes the disk-jet structure to align with the BH spin axis or that the disappearance of small-scale jets bound by the magnetic flux tubes leads to the disappearance of type-B QPOs. We observed three events regarding the B/C transitions, one of which occurred over a short time period from ∼9.2 Hz (C) to ∼4.8 Hz (B). The energy spectral analysis for the other two transitions shows that when type-C QPO is present, the Comptonization flux is higher, the spectrum is harder, and the inner radius of the disk changes insignificantly. We suggest that type-C QPOs probably originate from relatively stronger jets or the corona.
The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This ...work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2
/
years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.
We study electronic ordering instabilities of twisted bilayer graphene around the filling ofn=2electrons per supercell, where correlated insulator state and superconductivity have been recently ...observed. Motivated by the Fermi surface nesting and the proximity to Van Hove singularity, we introduce a hot-spot model to study the effect of various electron interactions systematically. Using the renormalization group method, we find thatdorp-wave superconductivity and charge or spin density wave emerge as the two types of leading instabilities driven by Coulomb repulsion. The density-wave state has a gapped energy spectrum aroundn=2and yields a single doubly degenerate pocket upon doping ton>2. The intertwinement of density wave and superconductivity and the quasiparticle spectrum in the density-wave state are consistent with experimental observations.
The CDEX-1 experiment conducted a search of low-mass (< 10GeV/c super(2)) weakly interacting massive particles dark matter at the China Jinping Underground Laboratory using a p-type point-contact ...germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report the hardware setup, detector characterization, data acquisition, and analysis procedures of this experiment. No excess of unidentified events is observed after the subtraction of the known background. Using 335.6 kg-days of data, exclusion constraints on the weakly interacting massive particle-nucleon spin-independent and spin-dependent couplings are derived.
Microstructure and voids evolution of a selective laser melted (SLM) AlSi10Mg alloy during tension were systematically investigated. The SLM AlSi10Mg sample is featured with a multi-level ...heterogeneous microstructure that is composed of melt pools (MPs), columnar Al grains and sub-cells. According to the Si morphologies and thermal history, the MP could be divided into three regions, including the fine structure zone (FSZ), remelted zone (RMZ) and heat-affected zone (HAZ), respectively. The Si segregation phenomenon on sub-cells boundaries is observed and may attributed to the constitutional supercooling. The tensile deformation behaviors of the vertical sample (V-sample) vary from the horizontal sample (H-sample) for that heterogeneous microstructure arises strain localization in V-sample. In addition, the voids have no obvious effect on the uniform plastic deformation, while they may affect the non-uniform deformation during tension. The combined effects of strain localization and void contribute to the earlier break in V-samples than in H-samples.
Using a total of 9.0 fb−1 of e+e− collision data with center-of-mass energies between 4.15 and 4.30 GeV collected by the BESIII detector, we search for the processes e+e−→γX(3872) with X(3872)→π0χcJ ...for J=0, 1, 2. We report the first observation of X(3872)→π0χc1, a new decay mode of the X(3872), with a statistical significance of more than 5σ for all systematic fit variations. Normalizing to the previously established process e+e−→γX(3872) with X(3872)→π+π−J/ψ, we find B(X(3872)→π0χc1)/B(X(3872)→π+π−J/ψ)=0.88−0.27+0.33±0.10, where the first error is statistical and the second is systematic. We set 90% confidence level upper limits on the corresponding ratios for the decays to π0χc0 and π0χc2 of 19 and 1.1, respectively.
Summary
Background
Pemphigus is a group of rare life‐threatening mucocutaneous autoimmune diseases, presenting mainly as two subtypes: pemphigus vulgaris (PV) and pemphigus foliaceus (PF). Inherited ...predispositions to pemphigus have long been speculated but they remain poorly understood.
Objectives
To identify common and specific nongenetic and genetic factors associated with pemphigus and its subtypes in the Chinese population.
Methods
A genome‐wide association study (GWAS) was performed in 496 unrelated patients with pemphigus (including 365 with PV and 104 with PF) and 1105 controls without pemphigus.
Results
A sex preference was observed only in PV (57·5% female) and not in PF (47·1% female). For male patients only, the mean age at diagnosis was significantly lower for PV than for PF (P < 0·001). The strongest associated single‐nucleotide polymorphisms are in the human leucocyte antigen (HLA) region: rs70993900 (PV; P = 1·5 × 10−45) and rs9469220 (PF; P = 1·1 × 10−8). HLA‐DQB1*05:03 ranks at the top (P = 4·7 × 10−40; odds ratio 12·4) in both subtypes, with significantly different risk allele frequency (RAFPV = 34·2% vs. RAFPF = 18·8% vs. RAFcontrol = 4·4%), whereas HLA‐DRB1*14:01 and HLA‐DRB1*04:06 are PV specific. HLA‐DQB1*03:03 and HLA‐DQB1*03:02 show significant subtype specificity in opposite directions. All of these associations were validated in the replication series with 147 cases of pemphigus and 604 controls. Multiple novel non‐HLA susceptibility loci were also identified in the GWAS.
Conclusions
This study represents the largest GWAS on pemphigus in the Chinese population published to date, and has allowed us to identify HLA haplotypes significantly shared between or specific to the two main subtypes of pemphigus.
What's already known about this topic?
Pemphigus is a group of autoimmune mucocutaneous diseases.
It has multiple subtypes associated with certain human leucocyte antigen (HLA) haplotypes in an ethnicity‐specific manner.
What does this study add?
This is the largest genome‐wide association study published on pemphigus to date.
We identified, for the first time, more than 100 single‐nucleotide polymorphisms (SNPs; six independent) at the HLA locus, with associations reaching genome‐wide significance.
Some of these SNPs are strongly associated with specific subtypes of pemphigus.
What is the translational message?
The identified new haplotypes can potentially serve as genetic markers to improve investigation of the epidemiology and pathogenesis of pemphigus and its specific subtypes.
Linked Comment: Geller. Br J Dermatol 2019; 180:713–714.
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Using a total of 11.0 fb^{-1} of e^{+}e^{-} collision data with center-of-mass energies between 4.009 and 4.6 GeV and collected with the BESIII detector at BEPCII, we measure fifteen exclusive cross ...sections and effective form factors for the process e^{+}e^{-}→Ξ^{-}Ξover ¯^{+} by means of a single baryon-tag method. After performing a fit to the dressed cross section of e^{+}e^{-}→Ξ^{-}Ξover ¯^{+}, no significant ψ(4230) or ψ(4260) resonance is observed in the Ξ^{-}Ξover ¯^{+} final states, and upper limits at the 90% confidence level on Γ_{ee}B for the processes ψ(4230)/ψ(4260)→Ξ^{-}Ξover ¯^{+} are determined. In addition, an excited Ξ baryon at 1820 MeV/c^{2} is observed with a statistical significance of 6.2-6.5σ by including the systematic uncertainty, and the mass and width are measured to be M=(1825.5±4.7±4.7) MeV/c^{2} and Γ=(17.0±15.0±7.9) MeV, which confirms the existence of the J^{P}=3/2^{-} state Ξ(1820).
•A simplified theoretical model is proposed to predict tip cracking and non-tip cracking by decoupling the S-shape fissure into three cracking models.•The specimens prepared by 3D-printed transparent ...resin material are employed to approximate the counterparts of rock-like materials for their similarities in fracture pattern.•Minimal research found that non-tip-cracking occurs in S-shape fissure by tested on a lab. The cracking behavior of S-shape fissures is different from that of straight fissures with respect to the occurrence of non-tip-cracking.
Non-tip cracking for kinked fissures has been investigated in our previous study. This paper reveals that non-tip cracking also occurs for smooth fissures without kinks. 3D printed photosensitive resin specimens with a smooth S-shape fissure are tested under uniaxial compression. The influence of geometry and orientation of the S-shape fissure on the specimen deformation and strength behaviour, especially the non-tip-cracking failure is investigated. Results show that two cracking patterns, tip-cracking and non-tip cracking, occurs in a similar trend with that observed for kinked fissures. The non-tip cracking is sensitive to the inclination angle β and the ratio between the amplitude and ratio of the amplitude to the half length of the S-shape fissure, i.e., the effective curvature A/a, as it only occurs when β equals to 30°, 45°, 60° and the A/a is equal to or greater than 2/7.5. A simplified piecewise linear crack model is proposed to predict the occurrence of the non-tip cracking failure. The S-shape fissure is approximated by three straight segments and the three failure models A, B and C corresponding to their equivalent straight segments are identified based on the maximum circumferential stress criterion. The cracking pattern of the S-shape fissure is governed by model A and C failure and the predicted cracking patterns match well with the respective experimental ones. The results from the present research complement the traditional fracture mechanics by extending the understanding about non-tip cracking failure.
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