Thermal damage assessment of metallic plates using a nonlinear electromagnetic acoustic resonance technique

Abstract(#br)Low efficiency of energy transition is generally considered to be the only weakness of electromagnetic ultrasonic transducers (EMATs). Electromagnetic acoustic resonance (EMAR) technique has been successfully used to overcome this disadvantage with a combination of the EMATs with the ultrasonic resonant method. In this paper, a nonlinear EMAR technique has been proposed to evaluate the thermal damage of metallic materials, which combines the feature of EMAR with the merit of higher harmonic generation that provides an effective indicator to material damage. The use of contactless EMATs can isolate the material nonlinearity and maintain the coupling condition consistently on measurements of higher harmonics generated. EMAR provides high enough signal magnitude for higher harmonic generated. An experimental scheme is proposed and applied to assess the thermal damage in aluminum and nickel plates. In addition, conventional EMAR techniques based on the measure of shear wave velocity and attenuation within a certain frequency range, are also carried out for the specimens. The experimental results show a monotonic relationship between the normalized amplitude of higher harmonic generated and the artificial thermal loading time, while no stable trends are observed by conventional linear EMAR approaches. The results in this paper indicate that nonlinear EMAR technique proposed can be used to assess the thermal damage in both nonferromagnetic and ferromagnetic materials, with improved reliability and sensitivity over linear one

Identifying distinctive tissue and fecal microbial signatures and the tumor-promoting effects of deoxycholic acid on breast cancer

IntroductionA growing body of evidence indicates that the dysbiosis of both mammary and intestinal microbiota is associated with the initiation and progression of breast tumors. However, the microbial characteristics of patients with breast tumors vary widely across studies, and replicable biomarkers for early-stage breast tumor diagnosis remain elusive.MethodsWe demonstrate a machine learning-based method for the analysis of breast tissue and gut microbial differences among patients with benign breast disease, patients with breast cancer (BC), and healthy individuals using 16S rRNA sequence data retrieved from eight studies. QIIME 2.0 and R software (version 3.6.1) were used for consistent processing. A naive Bayes classifier was trained on the RDP v16 reference database to assign taxonomy using the Vsearch software.ResultsAfter re-analyzing with a total of 768 breast tissue samples and 1,311 fecal samples, we confirmed that Halomonas and Shewanella were the most representative genera of BC tissue. Bacteroides are frequently and significantly enriched in the intestines of patients with breast tumor. The areas under the curve (AUCs) of random forest models were 74.27% and 68.08% for breast carcinoma tissues and stool samples, respectively. The model was validated for effectiveness via cohort-to-cohort transfer (average AUC =0.65) and leave-one-cohort-out (average AUC = 0.66). The same BC-associated biomarker Clostridium_XlVa exists in the tissues and the gut. The results of the in-vitro experiments showed that the Clostridium-specific-related metabolite deoxycholic acid (DCA) promotes the proliferation of HER2-positive BC cells and stimulates G0/G1 phase cells to enter the S phase, which may be related to the activation of peptide-O-fucosyltransferase activity functions and the neuroactive ligand–receptor interaction pathway.DiscussionThe results of this study will improve our understanding of the microbial profile of breast tumors. Changes in the microbial population may be present in both the tissues and the gut of patients with BC, and specific markers could aid in the early diagnosis of BC. The findings from in-vitro experiments confirmed that Clostridium-specific metabolite DCA promotes the proliferation of BC cells. We propose the use of stool-based biomarkers in clinical application as a non-invasive and convenient diagnostic method

Direct and indirect effects of climate on richness drive the latitudinal diversity gradient in forest trees

Data accessibility statement: Full census data are available upon reasonable request from the ForestGEO data portal, http://ctfs.si.edu/datarequest/ We thank Margie Mayfield, three anonymous reviewers and Jacob Weiner for constructive comments on the manuscript. This study was financially supported by the National Key R&D Program of China (2017YFC0506100), the National Natural Science Foundation of China (31622014 and 31570426), and the Fundamental Research Funds for the Central Universities (17lgzd24) to CC. XW was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB3103). DS was supported by the Czech Science Foundation (grant no. 16-26369S). Yves Rosseel provided us valuable suggestions on using the lavaan package conducting SEM analyses. Funding and citation information for each forest plot is available in the Supplementary Information Text 1.Peer reviewedPostprin

Contrasting elevational patterns of genetic variation in Euptelea pleiospermum along mountains at the core and edges of its latitudinal range

Patterns of genetic variation along both latitudinal and elevational gradients have been intensively studied in the last few decades. To date, however, elevational patterns of genetic diversity and gene flow remain rarely compared for the same species along mountains at the center and edges of its latitudinal range. We used nuclear microsatellite analysis to compare the elevational patterns of both genetic variation and gene flow for Euptelea pleiospermum along elevational transects on the Qinling (33 degrees N; leading edge), Shennongjia (31 degrees N; mid-latitude), and Emei (29 degrees N; rear edge) Mountains in China. First, we found no elevational pattern of genetic diversity along the two marginal mountains, but we found higher genetic diversity in the middle-altitude populations than in the low- and high-altitudes along the mid-latitude mountain. Second, there was no obvious genetic structure along the two marginal mountains, but individuals along the mid-latitude mountain were clustered into the upper and lower groups. Third, the contemporary gene flow along the two marginal mountains was higher than that along the mid-latitude mountain. Lastly, we found no isolation-by-distance along all three mountains and a significant isolation-by-elevation along the mid-latitude mountain but not along the two marginal mountains. Our results demonstrated that the elevational patterns of both genetic variation and gene flow for a tree species are different along mountains at the core and edges of its latitudinal range. These differences are likely associated with the discrepancies in spatial isolation, ecological stability, and vegetation types, but not historical events (e.g., post-glacial recolonization) at different latitudes

Numerical Investigation on Hydraulic Properties of Artificial-Splitting Granite Fractures during Normal and Shear Deformations

This study explores the effects of normal loading and shearing on hydraulic properties in roughness-walled rock fractures. The geometries of five fractures were measured by the 3D scanning technology. The flow simulation was performed for rough rock fractures with large displacements during normal loading and shearing by finite volume method (FVM). The results demonstrate that the deformation of fracture with increasing normal stress and shear causes nonuniform changes in void space geometry and further influences fracture permeability. Associated with normal displacement are an increase in contact area and a decrease in mechanical aperture. The transmissivity is decreasing by 3 orders of magnitude response to applied normal displacement values of 0.0 mm to 1.8 mm. In contrast, an increase in mechanical aperture and contact ratio that occurs with increasing shear displacement values of 0.0 mm to 4.0 mm is associated with decreasing distinctly transmissivity by 1.5–2 orders of magnitude. Based on the numerical results, an empirical equation is proposed to evaluate the effects of contact area and roughness of fracture on the hydraulic aperture. The good agreement between numerical results and the predicted results by the new model indicates that the proposed model is capable of estimating the hydraulic aperture of rock fractures through parametric analyses, compared with other published models from available literature. In addition, the new model succeeds in predicting the transmissivity in Develi and Babadagli (2014) water flow experiments

Sensitivity of seed germination to temperature of a relict tree species from different origins along latitudinal and altitudinal gradients: implications for response to climate change

Key messageSeeds of a relict tree species collected from high latitudes were more sensitive to temperature and warming could accelerate germination.AbstractSeed germination is a crucial process in a plant life cycle and is highly vulnerable to environmental change. Studying among-population variation in seed germination in response to environmental and geographic gradients is an important tool, allowing us to understand how plants adapt to different environmental conditions and to predict population dynamics under future climate change. Here, we collected seeds of Euptelea pleiospermum, a relict broad-leaved tree species, from six provenances along latitudinal and altitudinal gradients across its distribution in China. We investigated variation in seed germination percentage and germination timing of seeds from these different origins (low, middle, and high latitudes/altitudes) at three incubation temperatures (15 degrees C, 20 degrees C and 25 degrees C). The key results were as follows: first, seeds collected from high latitudes were more sensitive to temperature and was likely to benefit from the higher incubation temperature with increasing germination percentage and shorter germination timing; second, for seeds across latitudes, germination percentage of central populations was lower than that of marginal populations; seed origin and its interaction with temperature were the major drivers of germination percentage variation; germination timing was significantly affected by incubation temperature, and warming could accelerate germination; third, for seeds across altitudes, both germination percentage and germination timing were not significantly affected by seed origin, incubation temperature, or their interaction. Our results indicate that climate warming may influence the population dynamics of relict tree species by altering their seed germination patterns, especially for the leading-edge populations along latitudinal gradient. It is vital to take inter-population variation across species' geographic distribution into account when estimating the impact of environmental changes on plant species' distribution and population persistence

Adaptive strategies and driving factors of a montane riparian tree: Trait-specific mechanisms across latitude

Investigating the drivers of phenotypic and genetic divergence can reveal the underlying processes and strategies that species adopt in rapidly changing environments. However, knowledge of adaptive strategies and the underlying mechanisms is lacking for the majority of taxa, especially those living in habitats sensitive to climate change. Here, we investigated 20 populations of a Tertiary-relict tree species, Eaptelea pleiospermum (Eupteleaceae), scattered in a mountain riparian habitat in China. We integrated genetic, growth, and reproductive traits, and evaluated the relative contributions of climatic and soil factors on genetic and functional trait divergence. The E pleiospermurn populations were divided into south and north genetic clusters, and there were significant differences in leaf density and seed mass of adult trees between the two. The spatial pattern of genetic divergence resulted from effects of both isolation by distance (IBD) and isolation by environment (IBE), whereas the divergence of growth and reproductive traits resulted solely from IBE effects. Spatial distance and selection by temperalure and soils played dominant roles in genetic divergence. Precipitation drove he spatial divergence of sprouling. Both divergence of leaf density and seed mass were prominently induced by genetic divergence, and the influences might be enhanced by LemperaLure and soil nutrienis. We infer that E. pleiuspennum populations adopt a resource-conservalive strategy with low growth rates and higher sprouLing under flooding disturbance, with larger seeds for improved seedling recruitmenl. at lower lathucles. In contrast, high growth rare and sexual reproduction with small seeds are strategies adopted by populations al higher lathucles. We conclude Lhal sprouting ref-leas a plaslic response Lo precipiLiLion, and leaf densiLy and seed mass reflect local adaplion under selection by temperature and soil factors.The underlying mechanisms of species adaptation strategies were traitspecific. Temperature and soil conditions are likely the main ecological factors shaping plant divergence in montane riparian regions. (C) 2020 Elsevier BM. All rights reserved

Pattern and drivers of species-genetic diversity correlation in natural forest tree communities across a biodiversity hotspot

Aims Exploring species-genetic diversity correlation (SGDC) is essential for understanding spatial patterns of diversity and the underlying mechanisms. Until now, latitudinal patterns of species diversity (SD) and genetic diversity (GD) were rarely studied simultaneously. As the freezing-tolerance hypothesis predicts a decrease of SD from low to high latitudes and the central-marginal hypothesis predicts a unimodal pattern of GD along latitude, we hypothesized that SD and GD are uncorrelated. We also tested how climatic and edaphic factors affect the correlation between the two levels of biodiversity. Methods We measured (i) SD (species richness and Simpson's diversity index) and community dissimilarity of woody plants (63 plots), (ii) GD (allelic richness and expected heterozygosity) and genetic differentiation of a dominant tree species (Euptelea pleiospermum; 678 individuals from 21 populations) using nuclear microsatellite data, and (iii) climatic (annual mean precipitation, annual mean temperature, minimum temperature, maximum temperature, annual relative moisture, solar radiation, photosynthetically active radiation) and edaphic (total C, total N, total P, available P, K, Ca, Mg, Al, Fe, Mn, Ni, Zn, B, Mo, Cu, pH) variables of 21 sites. We conducted both linear and quadratic regression analyses of diversity parameters against latitude. Relationships between SD and GD were tested using Pearson's correlation. Pearson's and Spearman's. correlation coefficients were calculated between diversity parameters and environmental variables. We used stepwise multiple regression analysis to identify the significant environmental predictors of SD and GD. Important Findings We observed no significant correlation between measures of SD and GD. SD decreases with increasing latitude, which can be partly explained by the freezing-tolerance hypothesis, whereas GD presents a unimodal pattern along the latitudinal gradient, which is consistent with the prediction of the central-marginal hypothesis. The contrasting latitudinal patterns of SD and GD indicate that the two levels of biodiversity do not co-vary in space. Based on both correlation analysis and stepwise multiple regression analysis, SD is only related to climatic variables, whereas GD is mainly related to edaphic variables. Our results show that different geographical and environmental factors affect SD and GD, driving the non-significant correlation between the two fundamental levels of biodiversity. Furthermore, a significantly positive correlation was observed between genetic distance and community dissimilarity, both of which were significantly correlated with geographical distance