175 research outputs found

    On Constructing the Analytical Solutions for Localizations in a Slender Cylinder Composed of an Incompressible Hyperelastic Material

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    In this paper, we study the localization phenomena in a slender cylinder composed of an incompressible hyperelastic material subjected to axial tension. We aim to construct the analytical solutions based on a three-dimensional setting and use the analytical results to describe the key features observed in the experiments by others. Using a novel approach of coupled series-asymptotic expansions, we derive the normal form equation of the original governing nonlinear partial differential equations. By writing the normal form equation into a first-order dynamical system and with the help of the phase plane, we manage to solve two boundary-value problems analytically. The explicit solution expressions (in terms of integrals) are obtained. By analyzing the solutions, we find that the width of the localization zone depends on the material parameters but remains almost unchanged for the same material in the post-peak region. Also, it is found that when the radius-length ratio is relatively small there is a snap-back phenomenon. These results are well in agreement with the experimental observations. Through an energy analysis, we also deduce the preferred configuration and give a prediction when a snap-through can happen. Finally, based on the maximum-energy-distortion theory, an analytical criterion for the onset of material failure is provided.Comment: 27 pages 10 figure

    A Corpus-Based Study on Reporting Verbs Used in Doctoral Dissertations by Chinese EFL Learners

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    Reference to previous studies is an indispensable component in the academic discourse. Based on a self-built corpus, this study aims to analyze the use of reporting verbs in doctoral dissertations written by Chinese EFL learners with both qualitative and quantitative approaches. The findings show that Chinese EFL learners show a preference for citing previous studies as Discourse Acts. The absence of certain subtypes of Research Act verbs and Cognitive Act verbs reveals the reluctance of Chinese EFL learners to convey a critical viewpoint or judge the cited materials as false or incorrect. In terms of tense, simple present tense is most frequently used in the corpus to refer to previous studies as accepted facts. As for voice, active voice plays a dominant role in the corpus with a high proportion of 92.14%. At the same time, a small percentage of passive voice is used by writers to emphasize the essential contribution of certain cited scholars

    Microbial communities and arsenic biogeochemistry at the outflow of an alkaline sulfide-rich hot spring.

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    Alkaline sulfide-rich hot springs provide a unique environment for microbial community and arsenic (As) biogeochemistry. In this study, a representative alkaline sulfide-rich hot spring, Zimeiquan in the Tengchong geothermal area, was chosen to study arsenic geochemistry and microbial community using Illumina MiSeq sequencing. Over 0.26 million 16S rRNA sequence reads were obtained from 5-paired parallel water and sediment samples along the hot spring's outflow channel. High ratios of As(V)/AsSum (total combined arsenate and arsenite concentrations) (0.59-0.78), coupled with high sulfide (up to 5.87 mg/L), were present in the hot spring's pools, which suggested As(III) oxidation occurred. Along the outflow channel, AsSum increased from 5.45 to 13.86 μmol/L, and the combined sulfide and sulfate concentrations increased from 292.02 to 364.28 μmol/L. These increases were primarily attributed to thioarsenic transformation. Temperature, sulfide, As and dissolved oxygen significantly shaped the microbial communities between not only the pools and downstream samples, but also water and sediment samples. Results implied that the upstream Thermocrinis was responsible for the transformation of thioarsenic to As(III) and the downstream Thermus contributed to derived As(III) oxidation. This study improves our understanding of microbially-mediated As transformation in alkaline sulfide-rich hot springs

    Graphene-analogues boron nitride nanosheets confining ionic liquids: a high-performance quasi-liquid solid electrolyte

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    Solid electrolytes are one of the most promising electrolyte systems for safe lithium batteries, but the low ionic conductivity of these electrolytes seriously hinders the development of efficient lithium batteries. Here, a novel class of graphene-analogues boron nitride (g-BN) nanosheets confining an ultrahigh concentration of ionic liquids (ILs) in an interlayer and out-of-layer chamber to give rise to a quasi-liquid solid electrolyte (QLSE) is reported. The electron-insulated g-BN nanosheet host with a large specific surface area can confine ILs as much as 10 times of the host's weight to afford high ionic conductivity (3.85 × 10−3 S cm−1 at 25 °C, even 2.32 × 10−4 S cm−1 at −20 °C), which is close to that of the corresponding bulk IL electrolytes. The high ionic conductivity of QLSE is attributed to the enormous absorption for ILs and the confining effect of g-BN to form the ordered lithium ion transport channels in an interlayer and out-of-layer of g-BN. Furthermore, the electrolyte displays outstanding electrochemical properties and battery performance. In principle, this work enables a wider tunability, further opening up a new field for the fabrication of the next-generation QLSE based on layered nanomaterials in energy conversion devices

    Generation of cloned transgenic pigs rich in omega-3 fatty acids

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    Meat products are generally low in omega-3 (n-3) fatty acids, which are beneficial to human health. We describe the generation of cloned pigs that express a humanized Caenorhabditis elegans gene, fat-1, encoding an n-3 fatty acid desaturase. The hfat-1 transgenic pigs produce high levels of n-3 fatty acids from n-6 analogs, and their tissues have a significantly reduced ratio of n-6/n-3 fatty acids (P < 0.001). © 2006 Nature Publishing Group

    Clinical study of exhaled nitric oxide in children with asthma and allergic rhinitis

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    Objective·To determine the levels of nasally exhaled nitric oxide (FnNO) combined with fractional concentration of exhaled nitric oxide (FeNO) in children with asthma (AS) complicated with allergic rhinitis (AR), and analyze the levels of FnNO and FeNO in different clinical stages of AS with different severities of AR, so as to provide basis for guiding clinical diagnosis and treatment.Methods·Children diagnosed with AR with AS in the Department of Respiratory and Otolaryngology of Children's Hospital of Soochow University from April 2021 to November 2021 were included, and healthy children who visited the Department of Pediatrics for normal physical examination during the same period were enrolled as the control group. FeNO and FnNO were measured in all children to assess the severity of the children's diseases. The levels of FeNO and FnNO in children with AR and AS at different clinical stages of AS and their correlation with pulmonary function were compared and analyzed.Results·The proportion of persistent moderate-to-severe rhinitis was higher in the acute exacerbation stage of AS, and the proportion of intermittent mild rhinitis was higher in the clinical remission stage of AS. The FeNO level in the acute exacerbation stage were higher than that in the chronic persistent stage and clinical remission stage of AS (adjusted P=0.022, 0.000), and higher in the chronic persistent stage than that in the clinical remission stage of AS (adjusted P=0.002). The FnNO level in the acute exacerbation stage was higher than that in the clinical remission stage of AS (adjusted P=0.044). In the chronic persistent stage of AS, the FnNO levels in the persistent mild group and persistent moderate-to-severe control group were higher than those in the intermittent mild group (adjusted P=0.001, 0.000). In the clinical remission stage of AS, the FnNO levels in the persistent mild group and persistent moderate to severe control group were higher than those in the intermittent mild group (adjusted P=0.001, 0.007). In the intermittent mild group of AR, the FnNO levels in the acute exacerbation stage were higher than those in the chronic persistent stage and clinical remission stage of AS (adjusted P=0.010, 0.019). Part of pulmonary functions in the acute exacerbation stage of AS children were negatively correlated with the FeNO and FnNO levels (all P<0.05), while FEV1/pred in the chronic persistent stage was negatively correlated with FeNO level (P=0.010).Conclusion·FeNO and FnNO levels increased in the acute exacerbation stage of AS, and symptom scores of AR also increased. FeNO and FnNO levels were negatively correlated with pulmonary function in AS with AR children

    Jump-seq: Genome-Wide Capture and Amplification of 5-Hydroxymethylcytosine Sites

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    5-Hydroxymethylcytosine (5hmC) arises from the oxidation of 5-methylcytosine (5mC) by Fe2+ and 2-oxoglutarate-dependent 10–11 translocation (TET) family proteins. Substantial levels of 5hmC accumulate in many mammalian tissues, especially in neurons and embryonic stem cells, suggesting a potential active role for 5hmC in epigenetic regulation beyond being simply an intermediate of active DNA demethylation. 5mC and 5hmC undergo dynamic changes during embryogenesis, neurogenesis, hematopoietic development, and oncogenesis. While methods have been developed to map 5hmC, more efficient approaches to detect 5hmC at base resolution are still highly desirable. Herein, we present a new method, Jump-seq, to capture and amplify 5hmC in genomic DNA. The principle of this method is to label 5hmC by the 6-N3-glucose moiety and connect a hairpin DNA oligonucleotide carrying an alkyne group to the azide-modified 5hmC via Huisgen cycloaddition (click) chemistry. Primer extension starts from the hairpin motif to the modified 5hmC site and then continues to “land” on genomic DNA. 5hmC sites are inferred from genomic DNA sequences immediately spanning the 5-prime junction. This technology was validated, and its utility in 5hmC identification was confirmed

    Rnd3/RhoE Modulates HIF1α/VEGF Signaling by Stabilizing HIF1α and Regulates Responsive Cardiac Angiogenesis

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    The insufficiency of compensatory angiogenesis in the heart of patients with hypertension contributes to heart failure transition. The hypoxia-inducible factor 1α-vascular endothelial growth factor (HIF1α-VEGF) signaling cascade controls responsive angiogenesis. One of the challenges in reprograming the insufficient angiogenesis is to achieve a sustainable tissue exposure to the proangiogenic factors, such as HIF1α stabilization. In this study, we identified Rnd3, a small Rho GTPase, as a proangiogenic factor participating in the regulation of the HIF1α-VEGF signaling cascade. Rnd3 physically interacted with and stabilized HIF1α, and consequently promoted VEGFA expression and endothelial cell tube formation. To demonstrate this proangiogenic role of Rnd3 in vivo, we generated Rnd3 knockout mice. Rnd3 haploinsufficient (Rnd3(+/-)) mice were viable, yet developed dilated cardiomyopathy with heart failure after transverse aortic constriction stress. The poststress Rnd3(+/-) hearts showed significantly impaired angiogenesis and decreased HIF1α and VEGFA expression. The angiogenesis defect and heart failure phenotype were partially rescued by cobalt chloride treatment, a HIF1α stabilizer, confirming a critical role of Rnd3 in stress-responsive angiogenesis. Furthermore, we generated Rnd3 transgenic mice and demonstrated that Rnd3 overexpression in heart had a cardioprotective effect through reserved cardiac function and preserved responsive angiogenesis after pressure overload. Finally, we assessed the expression levels of Rnd3 in the human heart and detected significant downregulation of Rnd3 in patients with end-stage heart failure. We concluded that Rnd3 acted as a novel proangiogenic factor involved in cardiac responsive angiogenesis through HIF1α-VEGFA signaling promotion. Rnd3 downregulation observed in patients with heart failure may explain the insufficient compensatory angiogenesis involved in the transition to heart failure
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