1,054 research outputs found
Polytypism and Unexpected Strong Interlayer Coupling of two-Dimensional Layered ReS2
The anisotropic two-dimensional (2D) van der Waals (vdW) layered materials,
with both scientific interest and potential application, have one more
dimension to tune the properties than the isotropic 2D materials. The
interlayer vdW coupling determines the properties of 2D multi-layer materials
by varying stacking orders. As an important representative anisotropic 2D
materials, multilayer rhenium disulfide (ReS2) was expected to be random
stacking and lack of interlayer coupling. Here, we demonstrate two stable
stacking orders (aa and a-b) of N layer (NL, N>1) ReS2 from ultralow-frequency
and high-frequency Raman spectroscopy, photoluminescence spectroscopy and
first-principles density functional theory calculation. Two interlayer shear
modes are observed in aa-stacked NL-ReS2 while only one interlayer shear mode
appears in a-b-stacked NL-ReS2, suggesting anisotropic-like and isotropic-like
stacking orders in aa- and a-b-stacked NL-ReS2, respectively. The frequency of
the interlayer shear and breathing modes reveals unexpected strong interlayer
coupling in aa- and a-b-NL-ReS2, the force constants of which are 55-90% to
those of multilayer MoS2. The observation of strong interlayer coupling and
polytypism in multi-layer ReS2 stimulate future studies on the structure,
electronic and optical properties of other 2D anisotropic materials
Atomic resolution imaging of the two-component Dirac-Landau levels in a gapped graphene monolayer
The wavefunction of massless Dirac fermions is a two-component spinor. In
graphene, a one-atom-thick film showing two-dimensional Dirac-like electronic
excitations, the two-component representation reflects the amplitude of the
electron wavefunction on the A and B sublattices. This unique property provides
unprecedented opportunities to image the two components of massless Dirac
fermions spatially. Here we report atomic resolution imaging of the
two-component Dirac-Landau levels in a gapped graphene monolayer by scanning
tunnelling microscopy and spectroscopy. A gap of about 20 meV, driven by
inversion symmetry breaking by the substrate potential, is observed in the
graphene on both SiC and graphite substrates. Such a gap splits the n = 0
Landau level (LL) into two levels, 0+ and 0-. We demonstrate that the amplitude
of the wavefunction of the 0- LL is mainly at the A sites and that of the 0+ LL
is mainly at the B sites of graphene, characterizing the internal structure of
the spinor of the n = 0 LL. This provides direct evidence of the two-component
nature of massless Dirac fermions.Comment: 4 Figures in main text and 4 Figures in S
Recommended from our members
Microbial functional trait of rRNA operon copy numbers increases with organic levels in anaerobic digesters.
The ecological concept of the r-K life history strategy is widely applied in macro-ecology to characterize functional traits of taxa. However, its adoption in microbial communities is limited, owing to the lack of a measureable, convenient functional trait for classification. In this study, we performed an experiment of stepwise organic amendments in triplicate anaerobic digesters. We found that high resource availability significantly favored microbial r-strategists such as Bacillus spp. Incremental resource availability heightened average rRNA operon copy number of microbial community, resulting in a strong, positive correlation (r>0.74, P<0.008). This study quantifies how resource availability manipulations influence microbial community composition and supports the idea that rRNA operon copy number is an ecologically meaningful trait which reflects resource availability
Diagnostic value of multiple ultrasound diagnostic techniques for axillary lymph node metastases in breast cancer: A systematic analysis and network meta-analysis
BackgroundEarly diagnosis of axillary lymph node metastasis is very important for the recurrence and prognosis of breast cancer. Currently, Lymph node biopsy is one of the important methods to detect lymph node metastasis in breast cancer, however, its invasiveness might bring complications to patients. Therefore, this study investigated the diagnostic performance of multiple ultrasound diagnostic methods for axillary lymph node metastasis of breast cancer.Materials and methodsIn this study, we searched PubMed, Web of Science, CNKI and Wan Fang databases, conducted Bayesian network meta-analysis (NMA) on the studies that met the inclusion criteria, and evaluated the consistency of five different ultrasound imaging techniques in axillary lymph node metastasis of breast cancer. Funnel graph was used to evaluate whether it had publication bias. The diagnostic performance of each ultrasound imaging method was ranked using SUCRAResultsA total of 22 papers were included, US+CEUS showed the highest SUCRA values in terms of sensitivity (SEN) (0.874), specificity (SPE) (0.911), positive predictive value (PPV) (0.972), negative predictive value (NPV) (0.872) and accuracy (ACC) (0.990).ConclusionIn axillary lymph node metastasis of breast cancer, the US+CEUS combined diagnostic method showed the highest SUCRA value among the five ultrasound diagnostic methods. This study provides a theoretical basis for preoperative noninvasive evaluation of axillary lymph node metastases in breast cancer patients and clinical treatment decisions.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022351977
Rhizosphere Microenvironments of Eight Common Deciduous Fruit Trees Were Shaped by Microbes in Northern China
The rhizosphere microenvironment is the site of nutrient circulation and microbial community formation, and thus is an ongoing topic of research. Although research on this topic is extensive, studies into the rhizosphere microenvironment of fruit trees remain rare. To elucidate the mechanisms driving the fruit tree rhizosphere microenvironment, we assessed soil physicochemical properties, enzyme activities, the community-level physiological profile (CLPP) and microbial diversity in rhizospheric soils of eight common deciduous fruit trees in northern China. We found that the available minerals, pH, enzyme activities, microbial utilization of six types of carbon (C) substrates, and microbial diversity in the rhizosphere varied among tree species. Redundancy analysis (RDA) showed that rhizosphere microenvironmental parameters (ammonia nitrogen content, soil pH and invertase activity) were closely related to the soil microbial community. Further analysis revealed that the soil microbial utilization of six C sources, nitrate nitrogen content, and invertase activity were negatively correlated with Ambiguous species and Alternaria; however, these groups were positively correlated with pH. The ammonia nitrogen content was positively correlated with C source utilization and negatively correlated with Ambiguous, Lysobacter, Nitrospira, Alternaria, Fusarium, and Colletotrichum. Interestingly, invertase was closely linked to the microbial community, especially fungal diversity, and was positively correlated with plant-beneficial microbes such as Mortierella, Geomyces, Lysobacter, and Chaetomium, but negatively correlated with pathogenic microbes such as Alternaria, Fusarium, and Colletotrichum. Hence, rhizosphere soil physicochemical properties, enzyme activities and microbial community were significantly affected by tree species. Additionally, a variety of environmental factors were closely related to the microbial community in the rhizospheric soils of eight species of deciduous fruit trees
VBench: Comprehensive Benchmark Suite for Video Generative Models
Video generation has witnessed significant advancements, yet evaluating these
models remains a challenge. A comprehensive evaluation benchmark for video
generation is indispensable for two reasons: 1) Existing metrics do not fully
align with human perceptions; 2) An ideal evaluation system should provide
insights to inform future developments of video generation. To this end, we
present VBench, a comprehensive benchmark suite that dissects "video generation
quality" into specific, hierarchical, and disentangled dimensions, each with
tailored prompts and evaluation methods. VBench has three appealing properties:
1) Comprehensive Dimensions: VBench comprises 16 dimensions in video generation
(e.g., subject identity inconsistency, motion smoothness, temporal flickering,
and spatial relationship, etc). The evaluation metrics with fine-grained levels
reveal individual models' strengths and weaknesses. 2) Human Alignment: We also
provide a dataset of human preference annotations to validate our benchmarks'
alignment with human perception, for each evaluation dimension respectively. 3)
Valuable Insights: We look into current models' ability across various
evaluation dimensions, and various content types. We also investigate the gaps
between video and image generation models. We will open-source VBench,
including all prompts, evaluation methods, generated videos, and human
preference annotations, and also include more video generation models in VBench
to drive forward the field of video generation.Comment: Equal contributions from first four authors. Project page:
https://vchitect.github.io/VBench-project/ Code:
https://github.com/Vchitect/VBenc
Lot-to-lot consistency study of an Escherichia coli -produced bivalent human papillomavirus vaccine in adult women: a randomized trial.
An Escherichia. coli -produced HPV-16/18 bivalent vaccine has been proved to be well-tolerated and highly efficacious against diseases associated with vaccine HPV types. As a part of the multi-center, randomized, double-blind phase III clinical trial, this lot-to-lot consistency study aimed to assess the safety and immunogenicity consistency of this novel HPV vaccine, which is also one of the objectives of the phase III trial. A total of 3689 healthy women aged 18-45 years were enrolled and randomly assigned 1:1:1 to three lots of the HPV vaccine groups. The primary outcomes were the IgG antibody level at 1 month after the last dose (month 7). In the immunogenicity per-protocol set (PPS), almost all of the participants seroconverted at month 7 and remained seropositive at month 42. For each paired comparison of the three lot groups, the two-sides of 90% CIs of GMC ratios for both IgG and neutralizing antibodies for HPV-16 and HPV-18 at month 7 were within the equivalence interval [0.5, 2]. Lot consistency was also demonstrated at month 42. The majority of recorded solicited reactions were mild or moderate. The incidences of solicited reactions of Lot 2 and Lot 3 were slightly higher than Lot 1. However, the incidences of solicited reactions of ≥ grade 3 and solicited reactions by symptoms were all similar among the three lot groups. None of the SAEs was considered related to vaccination by the investigator. In conclusion, this study demonstrates lot-to-lot consistency of the 3 consecutive lots of the E. coli -produced HPV-16/18 bivalent vaccine
Risk factors for endometrial cancer : An umbrella review of the literature
Although many risk factors could have causal association with endometrial cancer, they are also prone to residual confounding or other biases which could lead to over- or underestimation. This umbrella review evaluates the strength and validity of evidence pertaining risk factors for endometrial cancer. Systematic reviews or meta-analyses of observational studies evaluating the association between non-genetic risk factors and risk of developing or dying from endometrial cancer were identified from inception to April 2018 using PubMed, the Cochrane database and manual reference screening. Evidence was graded strong, highly suggestive, suggestive or weak based on statistical significance of random-effects summary estimate, largest study included, number of cases, between-study heterogeneity, 95% prediction intervals, small study effects, excess significance bias and sensitivity analysis with credibility ceilings. We identified 171 meta-analyses investigating associations between 53 risk factors and endometrial cancer incidence and mortality. Risk factors were categorised: anthropometric indices, dietary intake, physical activity, medical conditions, hormonal therapy use, biochemical markers, gynaecological history and smoking. Of 127 meta-analyses including cohort studies, three associations were graded with strong evidence. Body mass index and waist-to-hip ratio were associated with increased cancer risk in premenopausal women (RR per 5 kg/m(2) 1.49; CI 1.39-1.61) and for total endometrial cancer (RR per 0.1unit 1.21; CI 1.13-1.29), respectively. Parity reduced risk of disease (RR 0.66, CI 0.60-0.74). Of many proposed risk factors, only three had strong association without hints of bias. Identification of genuine risk factors associated with endometrial cancer may assist in developing targeted prevention strategies for women at high risk.Peer reviewe
Preimplantation genetic testing guidelines of International Society of Reproductive Genetics
The International Society of Reproductive Genetics (ISRG) assembled a workgroup made up of clinicians, clinical laboratory directors, and scientists for the purpose of creating the guidelines for preimplantation genetic testing (PGT). The most up-to-date information and clinical insights for the optimal PGT practice were incorporated in these guidelines. Recommendations are provided for embryologists, medical geneticists, clinical laboratorians, and other healthcare providers to improve the wellbeing of patients seeking assisted reproductive treatment and their offspring
- …