263 research outputs found
3D Host Design Strategies Guiding “Bottom–Up” Lithium Deposition: A Review
Lithium metal batteries (LMBs) have the potential to be the next-generation rechargeable batteries due to the high theoretical specific capacity and the lowest redox potential of lithium metal. However, the practical application of LMBs is hindered by challenges such as the uncontrolled growth of lithium dendrites, unstable solid electrolyte interphase (SEI), and excessive volume change of Li metal. To solve these issues, the design of high-performance lithium metal anodes (LMAs) with various 3D structures is critical. Targeting at realizing the “bottom–up” Li deposition to fully utilize the 3D architecture, in recent years, strategies such as gradient host materials construction, magnetic field modulation, SEI component design, and so on have attracted intensive attention. This review begins with a fundamental discussion of the Li nucleation and deposition mechanism. The recent advances in the aspects of construction strategies and modification methods that enable the “bottom–up” Li deposition within advanced 3D host materials, with a particular emphasize on their design principles are comprehensively overviewed. Finally, future challenges and perspectives on the design of advanced hosts toward practical LMAs are proposed
Comparison of metagenomic samples using sequence signatures
BACKGROUND: Sequence signatures, as defined by the frequencies of k-tuples (or k-mers, k-grams), have been used extensively to compare genomic sequences of individual organisms, to identify cis-regulatory modules, and to study the evolution of regulatory sequences. Recently many next-generation sequencing (NGS) read data sets of metagenomic samples from a variety of different environments have been generated. The assembly of these reads can be difficult and analysis methods based on mapping reads to genes or pathways are also restricted by the availability and completeness of existing databases. Sequence-signature-based methods, however, do not need the complete genomes or existing databases and thus, can potentially be very useful for the comparison of metagenomic samples using NGS read data. Still, the applications of sequence signature methods for the comparison of metagenomic samples have not been well studied. RESULTS: We studied several dissimilarity measures, including d(2), d(2)(*) and d(2)(S) recently developed from our group, a measure (hereinafter noted as Hao) used in CVTree developed from Hao’s group (Qi et al., 2004), measures based on relative di-, tri-, and tetra-nucleotide frequencies as in Willner et al. (2009), as well as standard l(p) measures between the frequency vectors, for the comparison of metagenomic samples using sequence signatures. We compared their performance using a series of extensive simulations and three real next-generation sequencing (NGS) metagenomic datasets: 39 fecal samples from 33 mammalian host species, 56 marine samples across the world, and 13 fecal samples from human individuals. Results showed that the dissimilarity measure d(2)(S) can achieve superior performance when comparing metagenomic samples by clustering them into different groups as well as recovering environmental gradients affecting microbial samples. New insights into the environmental factors affecting microbial compositions in metagenomic samples are obtained through the analyses. Our results show that sequence signatures of the mammalian gut are closely associated with diet and gut physiology of the mammals, and that sequence signatures of marine communities are closely related to location and temperature. CONCLUSIONS: Sequence signatures can successfully reveal major group and gradient relationships among metagenomic samples from NGS reads without alignment to reference databases. The d(2)(S) dissimilarity measure is a good choice in all application scenarios. The optimal choice of tuple size depends on sequencing depth, but it is quite robust within a range of choices for moderate sequencing depths
Second order finite difference approximations for the two-dimensional time-space Caputo-Riesz fractional diffusion equation
In this paper, we discuss the time-space Caputo-Riesz fractional diffusion
equation with variable coefficients on a finite domain. The finite difference
schemes for this equation are provided. We theoretically prove and numerically
verify that the implicit finite difference scheme is unconditionally stable
(the explicit scheme is conditionally stable with the stability condition
) and 2nd order convergent in space direction, and
-th order convergent in time direction, where .Comment: 27 page
Unconventional polarization switching mechanism in (Hf, Zr)O2 ferroelectrics
HfO-based ferroelectric thin films are promising for their application
in ferroelectric devices. Predicting the ultimate magnitude of polarization and
understanding its switching mechanism are critical to realize the optimal
performance of these devices. Here, a generalized solid-state variable cell
nudged elastic band (VCNEB) method is employed to predict the switching pathway
associated with domain-wall motion in (Hf, Zr)O ferroelectrics. It is
found that the polarization reversal pathway, where three-fold coordinated O
atoms pass across the nominal unit-cell boundaries defined by the Hf/Zr atomic
planes, is energetically more favorable than the conventional pathway where the
O atoms do not pass through these planes. This finding implies that the
polarization orientation in the orthorhombic Pca2 phase of HfO nd
its derivatives is opposite to that normally assumed, predicts the spontaneous
polarization magnitude of about 70 C/cm that is nearly 50% larger
than the commonly accepted value, signifies a positive intrinsic longitudinal
piezoelectric coefficient, and suggests growth of ferroelectric domains, in
response to an applied electric field, structurally reversed to those usually
anticipated. These results provide important insights into the understanding of
ferroelectricity in HfO-based ferroelectrics.Comment: 34 pages, 28 figure
Xpert: Empowering Incident Management with Query Recommendations via Large Language Models
Large-scale cloud systems play a pivotal role in modern IT infrastructure.
However, incidents occurring within these systems can lead to service
disruptions and adversely affect user experience. To swiftly resolve such
incidents, on-call engineers depend on crafting domain-specific language (DSL)
queries to analyze telemetry data. However, writing these queries can be
challenging and time-consuming. This paper presents a thorough empirical study
on the utilization of queries of KQL, a DSL employed for incident management in
a large-scale cloud management system at Microsoft. The findings obtained
underscore the importance and viability of KQL queries recommendation to
enhance incident management.
Building upon these valuable insights, we introduce Xpert, an end-to-end
machine learning framework that automates KQL recommendation process. By
leveraging historical incident data and large language models, Xpert generates
customized KQL queries tailored to new incidents. Furthermore, Xpert
incorporates a novel performance metric called Xcore, enabling a thorough
evaluation of query quality from three comprehensive perspectives. We conduct
extensive evaluations of Xpert, demonstrating its effectiveness in offline
settings. Notably, we deploy Xpert in the real production environment of a
large-scale incident management system in Microsoft, validating its efficiency
in supporting incident management. To the best of our knowledge, this paper
represents the first empirical study of its kind, and Xpert stands as a
pioneering DSL query recommendation framework designed for incident management.Comment: Accepted as a reseach paper at ICSE 202
Developing a class of dual atom materials for multifunctional catalytic reactions
Dual atom catalysts, bridging single atom and metal/alloy nanoparticle catalysts, offer more opportunities to enhance the kinetics and multifunctional performance of oxygen reduction/evolution and hydrogen evolution reactions. However, the rational design of efficient multifunctional dual atom catalysts remains a blind area and is challenging. In this study, we achieved controllable regulation from Co nanoparticles to CoN4 single atoms to Co2N5 dual atoms using an atomization and sintering strategy via an N-stripping and thermal-migrating process. More importantly, this strategy could be extended to the fabrication of 22 distinct dual atom catalysts. In particular, the Co2N5 dual atom with tailored spin states could achieve ideally balanced adsorption/desorption of intermediates, thus realizing superior multifunctional activity. In addition, it endows Zn-air batteries with long-term stability for 800 h, allows water splitting to continuously operate for 1000 h, and can enable solar-powered water splitting systems with uninterrupted large-scale hydrogen production throughout day and night. This universal and scalable strategy provides opportunities for the controlled design of efficient multifunctional dual atom catalysts in energy conversion technologies
Identification and isolation of Genotype-I Japanese Encephalitis virus from encephalitis patients
Historically, Japanese Encephalitis virus (JEV) genotype III (GIII) has been responsible for human diseases. In recent years, JEV genotype I (GI) has been isolated from mosquitoes collected in numerous countries, but has not been isolated from patients with encephalitis. In this study, we report recovery of JEV GI live virus and identification of JEV GI RNA from cerebrospinal fluid (CSF) of encephalitis patients in JE endemic areas of China. Whole-genome sequencing and molecular phylogenetic analysis of the JEV isolate from the CSF samples was performed. The isolate in this study is highly similar to other JEV GI strains which isolated from mosquitoes at both the nucleotide and deduced amino acid levels. Phylogenetic analysis based on the genomic sequence showed that the isolate belongs to JEV GI, which is consistent with the phylogenetic analysis based on the pre-membrane (PrM) and Glycoprotein genes. As a conclusion, this is the first time to isolate JEV GI strain from CSF samples of encephalitis patients, so continuous survey and evaluate the infectivity and pathogenecity of JEV GI strains are necessary, especially for the JEV GI strains from encephalitis patients. With respect to the latter, because all current JEV vaccines (live and inactivated are derived from JEV GIII strains, future studies should be aimed at investigating and monitoring cross-protection of the human JEV GI isolates against widely used JEV vaccines
Construction of a High-Density Linkage Map and QTL Fine Mapping for Growth- and Sex-Related Traits in Channel Catfish (Ictalurus punctatus)
A high-density genetic linkage map is of particular importance in the fine mapping for important economic traits and whole genome assembly in aquaculture species. The channel catfish (Ictalurus punctatus), a species native to North America, is one of the most important commercial freshwater fish in the world. Outside of the United States, China has become the major producer and consumer of channel catfish after experiencing rapid development in the past three decades. In this study, based on restriction site associated DNA sequencing (RAD-seq), a high-density genetic linkage map of channel catfish was constructed by using single nucleotide polymorphisms (SNPs) in a F1 family composed of 156 offspring and their two parental individuals. A total of 4,768 SNPs were assigned to 29 linkage groups (LGs), and the length of the linkage map reached 2,480.25 centiMorgans (cM) with an average distance of 0.55 cM between loci. Based on this genetic linkage map, 223 genomic scaffolds were anchored to the 29 LGs of channel catfish, and a total length of 704.66 Mb was assembled. Quantitative trait locus (QTL) mapping and genome-wide association analysis identified 10 QTLs of sex-related and six QTLs of growth-related traits at LG17 and LG28, respectively. Candidate genes associated with sex dimorphism, including spata2, spata5, sf3, zbtb38, and fox, were identified within QTL intervals on the LG17. A sex-linked marker with simple sequence repeats (SSR) in zbtb38 gene of the LG17 was validated for practical verification of sex in the channel catfish. Thus, the LG17 was considered as a sex-related LG. Potential growth-related genes were also identified, including important regulators such as megf9, npffr1, and gas1. In a word, we constructed the high-density genetic linkage map and developed the sex-linked marker in channel catfish, which are important genetic resources for future marker-assisted selection (MAS) of this economically important teleost
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