19 research outputs found

    Crystal structure and electrical properties of textured Ba2Bi4Ti5O18 ceramics

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    Highly textured Ba2Bi4Ti5O18 ceramic was prepared by spark plasma sintering (SPS). X-ray diffraction of the ceramics revealed the coexistence of a major ferroelectric phase (Space group, SG: B2cb) and a minor paraelectric phase (SG: I4/mmm) at room temperature. A diffused phase transition was observed at around 240 °C. The evolution of the switching current peaks in the electric current vs. electric field (I-E) loops with increasing temperature was interpreted by the structural changes and temperature dependent polarisation reversal processes. The slim polarisation vs. electric field (P-E) loops, the extra switching current peaks in the I-E loops and the non-zero piezoelectric d33 coefficient indicate that Ba2Bi4Ti5O18 is a relaxor ferroelectric material. The recoverable energy density (0.41 ± 0.01 J/cm3) of Ba2Bi4Ti5O18 ceramics in the perpendicular direction to the SPS pressing direction is close to that of Pb(Mg1/3Nb2/3)O3-based ceramics. The obtained results suggest Ba2Bi4Ti5O18 ceramics might be promising for energy storage applications

    Exploring PVFM-Based Janus Membrane-Supporting Gel Polymer Electrolyte for Highly Durable Li–O<sub>2</sub> Batteries

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    Electrolyte is the key to constructing the ionic transport paths and O<sub>2</sub> gas diffusion routes in the cathode as well as maintaining the electrode interfacial stability in view of the complex chemistry of Li–O<sub>2</sub> batteries. A novel poly­(vinyl formal) (PVFM)-based Janus membrane, which is prepared via coating multiwalled carbon nanotubes (MWCNTs) on the porous side of the cross-linked PVFM membrane, has been proposed herein to achieve membrane-supporting gel polymer electrolyte (GPE) for Li–O<sub>2</sub> batteries. Within Li–O<sub>2</sub> batteries, the dense side of PVFM-based Janus membrane demonstrates a good compatibility with lithium metal anode, while the other side with MWCNTs coating reserves much more solvent on the surface, assisting the cathode to form enlarged electrolyte-wetted interface. Moreover, the comparative studies indicate that PVFM-based Janus membrane also can provide a conductive pathway, modulate the morphology of the discharge products, and produce accommodation space for the products. So, the Li–O<sub>2</sub> batteries containing PVFM-based Janus membrane-supporting GPE not only demonstrate significantly improved discharge capacity and cycling stability, i.e., 150 times at 1000 mAh g<sup>–1</sup> capacity limitation, but also a narrow voltage gap of 0.90 V and an excellent rate performance up to 1000 mA g<sup>–1</sup>

    Image1_Transcriptomic profiles of poplar (Populus simonii Ă— P. nigra) cuttings during adventitious root formation.JPEG

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    The formation of adventitious roots (ARs) is vital for the vegetative propagation of poplars. However, the relevant mechanisms remain unclear. To reveal the underlying molecular mechanism, we used RNA-seq to investigate the transcriptional alterations of poplar cuttings soaked in water for 0, 2, 4, 6, 8, and 10 d; 3,798 genes were differentially expressed at all the time points, including 2,448 upregulated and 1,350 downregulated genes. Biological processes including “cell cycle,” “photosynthesis,” “regulation of hormone levels,” and “auxin transport” were enriched in the differentially expressed genes (DEGs). KEGG results showed that the common DEGs were most enriched in the pathway of “Carbon fixation in photosynthetic organisms” and “Starch and sucrose metabolism.” We further dissected 38 DEGs related to root and auxin, including two lateral root primordium 1 (LRP1), one root meristem growth factor (RGF9), one auxin-induced in the root (AIR12), three rooting-associated genes (AUR1 and AUR3), eight auxin transcription factors (ARFs and LBDs), 10 auxin respective genes (SAURs and GH3s), nine auxin transporters (PINs, ABCs, LAX2, and AUXs), and four auxin signal genes (IAAs and TIR1). We found that the rooting abilities of poplar cuttings with and without leaves are different. By applying different concentrations of IBA and sucrose to the top of cuttings without leaves, we found that 0.2 mg/ml IBA and 2 mg/ml sucrose had the best effect on promoting AR formation. The transcriptome results indicated photosynthesis may influence AR formation in poplar cuttings with leaves and revealed a potential regulatory mechanism of leafy cuttage from poplar cuttings. In addition, we provided a new perspective to resolve rooting difficulties in recalcitrant species.</p

    Consideration of climate change impacts will improve the efficiency of protected areas on the Qinghai-Tibet Plateau

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    The protection of migratory birds and their habitats is important to the ecological stability of the Qinghai-Tibet Plateau (QTP). Currently protected areas (PAs) were designed in accordance with species distribution patterns under current climatic conditions, thus ignoring climate change will lead to a decrease in the protection efficiency of PAs. In this study, using the flagship species Grus nigricollis, as an example, we used the maximum entropy (MaxEnt) model to simulate the distributions and conservation status of G. nigricollis and optimized the existing PA boundaries . The results showed that (1) suitable habitat- for G. nigricollis accounts for 12.48% of the QTP area, and the PAs established under current climatic conditions cover 17.84% of this suitable habitat area; (2) future climate changes will influence the distribution and quality of G. nigricollis habitats, and the average protection efficiency of the current PAs in four climatic scenarios will decrease from 17.84% to 15.31%; and (3) through optimization, the efficiency of existing PAs can be increased by 0.75 times and reach 28.37%, indicating PA planning must consider not only current climate conditions but also the effects of climate changes. Our results aim to address shortcomings in the conservation efficiency of PAs and provide an example for resolving mismatched PA boundaries and habitat changes for species.</p

    Sirt6 promotes DNA damage repair in osteoarthritis chondrocytes by activating the Keap1/Nrf2/HO-1 signaling pathway

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    The aim of this study was to explore the effect and mechanism of Sirt6 on DNA damage repair in OA chondrocytes. Cartilage tissues were collected from OA patients with knee arthroplasty and traumatic amputation patients without OA. Besides, 7-week-old male C57BL/6 mice were randomly divided into Control and OA groups; CHON-001 cells of corresponding groups were treated with 10 ng/ml interleukin (IL)-1β, respectively. Subsequently, Sirt6 or siNrf2 was over-expressed in CHON-001 cells to observe the effect of Sirt6 on DNA damage and senescence of chondrocytes by IL-1β through the nuclear factor E2-related factor 2 (Nrf2) signaling pathway. The expression level of Sirt6 in human and mouse OA cartilage tissues was significantly decreased. However, 24 h of treatment with IL-1β significantly decreased the expression of Sirt6 in chondrocytes, induced DNA damage, and promoted cellular senescence. In addition, over-expression of Sirt6 promoted DNA damage repair and inhibited cellular senescence in IL-1β-induced chondrocytes. Moreover, the overexpression of Sirt6 activated the Keap1/Nrf2/HO-1 signaling pathway in chondrocytes, while knockdown of Nrf2 expression inhibited the DNA damage repair and anti-senescence effects of Sirt6 on IL-1β-treated chondrocytes. Sirt6 may reduce DNA damage and cellular senescence in OA chondrocytes induced by IL-1β through activating the Keap1/Nrf2/HO-1 signaling pathway.</p

    Pregnancy-Induced Metabolic Phenotype Variations in Maternal Plasma

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    Metabolic variations occur during normal pregnancy to provide the growing fetus with a supply of nutrients required for its development and to ensure the health of the woman during gestation. Mass spectrometry-based metabolomics was employed to study the metabolic phenotype variations in the maternal plasma that are induced by pregnancy in each of its three trimesters. Nontargeted metabolomics analysis showed that pregnancy significantly altered the profile of metabolites in maternal plasma. The levels of six metabolites were found to change significantly throughout pregnancy, with related metabolic pathway variations observed in biopterin metabolism, phospholipid metabolism, amino acid derivatives, and fatty acid oxidation. In particular, there was a pronounced elevation of dihydrobiopterin (BH<sub>2</sub>), a compound produced in the synthesis of dopa, dopamine, norepinephrine, and epinephrine, in the second trimester, whereas it was markedly decreased in the third trimester. The turnover of BH<sub>2</sub> and tryptophan catabolites indicated that the fluctuations of neurotransmitters throughout pregnancy might reveal the metabolic adaption in the maternal body for the growth of the fetus. Furthermore, 11 lipid classes and 41 carnitine species were also determined and this showed variations in the presence of long-chain acylcarnitines and lysophospholipids in later pregnancy, suggesting changes of acylcarnitines and lysophospholipids to meet the energy demands in pregnant women. To our knowledge, this work is the first report of dynamic metabolic signatures and proposed related metabolic pathways in the maternal plasma for normal pregnancies and provided the basis for time-dependent metabolic trajectory against which disease-related disorders may be contrasted

    LC–MS-Based Urinary Metabolite Signatures in Idiopathic Parkinson’s Disease

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    Increasing evidence has shown that abnormal metabolic phenotypes in body fluids reflect the pathogenesis and pathophysiology of Parkinson’s disease (PD). These body fluids include urine; however, the relationship between, specifically, urinary metabolic phenotypes and PD is not fully understood. In this study, urinary metabolites from a total of 401 clinical urine samples collected from 106 idiopathic PD patients and 104 normal control subjects were profiled by using high-performance liquid chromatography coupled to high-resolution mass spectrometry. Our study revealed significant correlation between clinical phenotype and urinary metabolite profile. Metabolic profiles of idiopathic PD patients differed significantly and consistently from normal controls, with related metabolic pathway variations observed in steroidogenesis, fatty acid beta-oxidation, histidine metabolism, phenylalanine metabolism, tryptophan metabolism, nucleotide metabolism, and tyrosine metabolism. In the fruit fly <i>Drosophila melanogaster</i>, the alteration of the kynurenine pathway in tryptophan metabolism corresponded with pathogenic changes in the alpha-synuclein overexpressed <i>Drosophila</i> model of PD. The results suggest that LC–MS-based urinary metabolomic profiling can reveal the metabolite signatures and related variations in metabolic pathways that characterize PD. Consistent PD-related changes across species may provide the basis for understanding metabolic regulation of PD at the molecular level
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