Abstract
Iron-chalcogenide superconductors have emerged as a promising Majorana platform for topological quantum computation. By combining topological band and superconductivity in a single material, ...they provide significant advantage to realize isolated Majorana zero modes. However, iron-chalcogenide superconductors, especially Fe(Te,Se), suffer from strong inhomogeneity which may hamper their practical application. In addition, some iron-pnictide superconductors have been demonstrated to have topological surface states, yet no Majorana zero mode has been observed inside their vortices, raising a question of universality about this new Majorana platform. In this work, through angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy measurement, we identify Dirac surface states and Majorana zero modes, respectively, for the first time in an iron-pnictide superconductor, CaKFe
4
As
4
. More strikingly, the multiple vortex bound states with integer-quantization sequences can be accurately reproduced by our model calculation, firmly establishing Majorana nature of the zero mode.
Since its emergence in December 2019, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has developed into a global pandemic within a matter of months. While subunit vaccines are one of ...the prominent options for combating coronavirus disease 2019 (COVID‐19), the immunogenicity of spike protein‐based antigens remains unknown. When immunized in mice, the S1 domain induced much higher IgG and IgA antibody levels than the receptor‐binding domain (RBD) and more efficiently neutralized SARS‐CoV‐2 when adjuvanted with alum. It is inferred that a large proportion of these neutralization epitopes are located in the S1 domain but outside the RBD and that some of these are spatial epitopes. This finding indicates that expression systems with posttranslational modification abilities are important to maintain the natural configurations of recombinant spike protein antigens and are critical for effective COVID‐19 vaccines. Further, adjuvants prone to a Th1 response should be considered for S1‐based subunit COVID‐19 vaccines to reduce the potential risk of antibody‐dependent enhancement of infection.
Highlights
Antibodies induced by the S1 domain neutralized SARS‐Cov‐2 more efficiently than those induced by the receptor‐binding domain (RBD). Antibodies induced by the S1 domain produced from HEK293K cells neutralized SARS‐Cov‐2 more efficiently than those induced by the S1 domain produced from E. coli. Both the S1 domain and the RBD induced a highly Th2 response when adjuvanted with alum.
Alzheimer’s disease (AD) is the most common form of dementia but has no effective treatment. A comprehensive investigation of cell type-specific responses and cellular heterogeneity in AD is required ...to provide precise molecular and cellular targets for therapeutic development. Accordingly, we perform single-nucleus transcriptome analysis of 169,496 nuclei from the prefrontal cortical samples of AD patients and normal control (NC) subjects. Differential analysis shows that the cell type-specific transcriptomic changes in AD are associated with the disruption of biological processes including angiogenesis, immune activation, synaptic signaling, and myelination. Subcluster analysis reveals that compared to NC brains, AD brains contain fewer neuroprotective astrocytes and oligodendrocytes. Importantly, our findings show that a subpopulation of angiogenic endothelial cells is induced in the brain in patients with AD. These angiogenic endothelial cells exhibit increased expression of angiogenic growth factors and their receptors (i.e., EGFL7, FLT1, and VWF) and antigen-presentation machinery (i.e., B2M and HLA-E). This suggests that these endothelial cells contribute to angiogenesis and immune response in AD pathogenesis. Thus, our comprehensive molecular profiling of brain samples from patients with AD reveals previously unknown molecular changes as well as cellular targets that potentially underlie the functional dysregulation of endothelial cells, astrocytes, and oligodendrocytes in AD, providing important insights for therapeutic development.
Carbon dioxide (CO2) is cheap, renewable, abundant, and nontoxic carbon feedstocks in chemical reactions. In the past two decades, utilization of CO2 in polymer science has become a meaningful topic ...bridging two separate subjects, namely CO2 valorization and sustainable polymer synthesis. This review summarizes the recent progress in CO2 copolymer materials from synthesis to material performance adjustment, focusing on commercialized or potential commodity sustainable materials such as biodegradable polycarbonates and new structure polyurethanes from CO2‐polyol building blocks.
In the past two decades, utilization of CO2 in polymer science has become a meaningful topic bridging two separate subjects, namely CO2 valorization and sustainable polymer synthesis. This review summarizes the recent progress in CO2 copolymer materials from synthesis to material performance adjustment, focusing on commercialized or potential commodity sustainable materials such as biodegradable polycarbonates and new structure polyurethanes from CO2‐polyol building blocks.
The long‐range magnetic ordering in frustrated magnetic systems is stabilized by coupling magnetic moments to various degrees of freedom, for example, by enhancing magnetic anisotropy via lattice ...distortion. Here, the unconventional spin‐lattice coupled metamagnetic properties of atomically‐thin CrOCl, a van der Waals antiferromagnet with inherent magnetic frustration rooted in the staggered square lattice, are reported. Using temperature‐ and angle‐dependent tunneling magnetoconductance (TMC), in complementary with magnetic torque and first‐principles calculations, the antiferromagnetic (AFM)‐to‐ferrimagnetic (FiM) metamagnetic transitions (MTs) of few‐layer CrOCl are revealed to be triggered by collective magnetic moment flipping rather than the established spin‐flop mechanism, when external magnetic field (H) enforces a lattice reconstruction interlocked with the five‐fold periodicity of the FiM phase. The spin‐lattice coupled MTs are manifested by drastic jumps in TMC, which show anomalous upshifts at the transition thresholds and persist much higher above the AFM Néel temperature. While the MTs exhibit distinctive triaxial anisotropy, reflecting divergent magnetocrystalline anisotropy of the c‐axis AFM ground state, the resulting FiM phase has an a‐c easy plane in which the magnetization axis is freely rotated by H. At the 2D limit, such a field‐tunable FiM phase may provide unique opportunities to explore exotic emergent phenomena and novel spintronics devices.
Distinct from the established spin‐flop type metamagnetism, this work reports the unconventional spin‐lattice interlocked metamagnetism in few‐layer CrOCl down to the monolayer thickness. These unconventional metamagnetic transitions produce a unique field‐tunable ferrimagnetic phase with the magnetization axis freely rotated by magnetic field within an easy plane.
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•An improved COPK method is proposed for the covered karst groundwater vulnerability assessment, which is modified from the widely used COP method according to the unique ...hydrogeological features in northern China.•The COPK method is used in the Baotu Spring basin in Jinan City as a typical representative.•Most of the study area exhibits moderate to low karst groundwater vulnerability.•The nitrate concentration in karst groundwater demonstrated that the improved COPK method has much better performance than the original COP method.
Karst in China is characterized by a wide distribution, diverse forms, well-developed features, and excellent preservation, making it a representative example on a global scale. The semi-arid karst in northern China, widely distributed in many provinces, has unique hydrogeological features, including covered karst, weak karst development, thick aquifers, highly interconnected fissure network, and numerous karst springs, making it difficult to directly apply the COP method which is widely used in karst groundwater vulnerability assessment in this area. Additionally, the quality of the karst groundwater in many northern China cities is facing a threat in recent years, making it urgent to evaluate the vulnerability of the karst groundwater. This study aims to develop an improved COPK method for the covered karst groundwater vulnerability assessment modified from the widely used COP method, and to use it in the Baotu Spring basin in Jinan City, as a typical representative of the covered karst area in northern China. The assessment result by the improved COPK method shows that most of the study area exhibits moderate to low karst groundwater vulnerability, and the area with very high to high vulnerability is situated in the Middle Ordovician-Upper Cambrian Chaomidian Formation limestone exposed area. The above results by the improved COPK method are more consistent with the hydrogeological conditions than those by the original COP method. A comparison of nitrate contamination map to the groundwater vulnerability map reveals the more efficient performance of the improved COPK method compared to the original COP method in vulnerability assessment of the typical covered karst areas in northern China. This paper can provide a reference for karst groundwater vulnerability assessment of covered karst areas in northern China, as well as other countries and regions with similar hydrogeological conditions, which can provide valuable support for groundwater pollution control efforts.
Epigenetic alterations frequently participate in the onset of hematological malignancies. Histone deacetylases (HDACs) are essential for regulating gene transcription and various signaling pathways. ...Targeting HDACs has become a novel treatment option for hematological malignancies. Chidamide is the first oral selective HDAC inhibitor for HDAC1, HDAC2, HDAC3, and HDAC10 and was first approved for the treatment of R/R peripheral T‐cell lymphoma by the China Food and Drug Administration in 2014. Chidamide was also approved under the name Hiyasta (HBI‐8000) in Japan in 2021. In vitro studies revealed that chidamide could inhibit proliferation and induce apoptosis via cell cycle arrest and the regulation of apoptotic proteins. In clinical studies, chidamide was also efficacious in multiple myeloma, acute leukemia and myelodysplastic syndrome. This review includes reported experimental and clinical data on chidamide monotherapy or chidamide treatment in combination with chemotherapy for various hematological malignancies, offering a rationale for the renewed exploration of this drug.
•Working conditions of coolant R134a, R22 and R410A are tested for heat pipe system.•The condition and reason of the best filling ratio is given.•On a given heat transfer temperature difference, ...R410A coolant has the best heat transfer ability.
This paper mainly studied the influence factors of separated heat pipe system. Such factors include the type of Freon coolant and filling ratio. R134a, R22 and R410A are tested. Separated heat pipe system can be used in data center cooling. In order to be more similar to the real data center cooling system, there are two evaporators which are connected in parallel and the system uses one plate heat exchanger as condenser. A room in constant temperature controlled by enthalpy difference laboratory is used as heat source while chilled water is heat sink. The paper analysis the relationship between filling ratio and heat transfer capacity and make a comparison between the heat transfer capacity of each coolant. The experiment results find that with the increasing of filling ratio, the heat transfer capacity first increases, then almost remains constant. Finally, when filling ratio is high enough, heat transfer capacity decreases. The reason of this phenomenon is given in the paper. The results of the experiment are useful to engineering.
Unsupervised flood detection in large areas using Synthetic Aperture Radar (SAR) data always faces the challenge of automatic thresholding, because the histograms of large-scale images are unimodal, ...which thus makes it difficult to determine the threshold. In this paper, an iteratively multi-scale chessboard segmentation-based tiles selection method is introduced. This method includes a robust search procedure for tiles which obey bimodal Gaussian distribution, and a non-parametric histogram-based thresholding algorithm for thresholds identifying water areas. Then, the thresholds are integrated into the region-growing algorithm to obtain a consistent flood map. In addition, a classification refinement technique using multiresolution segmentation is proposed to address the omission in a heterogeneous flood area caused by water surface roughening due to weather factors (e.g., wind or rain). Experiments on the flooded area of Jialing River on July 2018 using Sentinel-1 images show a high classification accuracy of 99.05% through the validation of Landsat-8 data, indicating the validity of the proposed method.
Yak is an important livestock animal for the people indigenous to the harsh, oxygen‐limited Qinghai‐Tibetan Plateau and Hindu Kush ranges of the Himalayas. The yak genome was sequenced in 2012, but ...its assembly was fragmented because of the inherent limitations of the Illumina sequencing technology used to analyse it. An accurate and complete reference genome is essential for the study of genetic variations in this species. Long‐read sequences are more complete than their short‐read counterparts and have been successfully applied towards high‐quality genome assembly for various species. In this study, we present a high‐quality chromosome‐scale yak genome assembly (BosGru_PB_v1.0) constructed with long‐read sequencing and chromatin interaction technologies. Compared to an existing yak genome assembly (BosGru_v2.0), BosGru_PB_v1.0 shows substantially improved chromosome sequence continuity, reduced repetitive structure ambiguity, and gene model completeness. To characterize genetic variation in yak, we generated de novo genome assemblies based on Illumina short reads for seven recognized domestic yak breeds in Tibet and Sichuan and one wild yak from Hoh Xil. We compared these eight assemblies to the BosGru_PB_v1.0 genome, obtained a comprehensive map of yak genetic diversity at the whole‐genome level, and identified several protein‐coding genes absent from the BosGru_PB_v1.0 assembly. Despite the genetic bottleneck experienced by wild yak, their diversity was nonetheless higher than that of domestic yak. Here, we identified breed‐specific sequences and genes by whole‐genome alignment, which may facilitate yak breed identification.
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