40 research outputs found

    Development of a Mix Design Method for Multiplexed Powder Self-Compacting Concrete Based on the Multiscale Rheological Threshold Theory

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    The multiscale rheological threshold theory can guide the mix design of self-compacting concrete (SCC) from a trans-scale view. Through the paste thresholds calculated by the mini-slump flow test results, the workability of SCC can be predicted. However, this method shows insufficient prediction accuracy when handling multiplexed powder. In the existing threshold calculation formula, the characteristics of powder materials were described through empirical values, without considering the specific properties of various powders. This paper focuses on the application of the multiscale rheological threshold theory to multiplexed powder SCCs. Through the research on the characteristics of powder materials, especially D50 and Span, the effect of the powder properties on paste thresholds was carried out. The prediction accuracies were confirmed by four sets of self-compacting mixtures at paste and concrete scales and were verified with another set of tests. There are a total of 45 paste and 45 SCC test results with multiplexed powders, including cement, fly ash, and limestone powder. The predicting accuracies are expressed as the relative accuracy Δ and the accuracy index Δâ€Č, calculated by the comparison of self-compacting zones at paste and SCC scales. The calculation results showed that Δ and Δâ€Č of the modified method increased. This modified method can be efficient for the mix design of SCC containing multiplexed powders

    Dual-salts of LiTFSI and LiODFB for high voltage cathode LiNi0.5Mn1.5O4

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    The LiNi0.5Mn1.5O4 has been investigated as promising because of its high operating voltage (4.7 V vs. Li+/Li) and decent specific capacity. Despite these advantages, however, the market penetration of this material was significantly hindered by the lack of proper electrolytes that can work stably up to 5 V. To achieve better cycling stability, mixed salts of lithium bis (trifluoromethanesulfonylimide) (LiTFSI) and lithium difluoro (oxalate) borate (LiODFB) are used in LiNi0.5Mn1.5O4-based batteries to replace the lithium hexafluoride phosphate (LiPF6) salt in non-aqueous electrolytes. The SEM and CV data indicate that the corrosion to Al current collector caused by LiTFSI-based electrolytes under high voltage (similar to 5 V vs. Li+/Li) can be largely reduced by adding LiODFB into LiTFSI-based electrolytes. And a boron-based passivation layer from the oxidative decomposition of LiODFB to suppress the corrosion based on the XPS tests results. In addition, the LiTFSI0.5-LiODFB0.5-based electrolyte has better cycling stability and rate capability for LiNi0.5Mn1.5O4-based cells than LiPF6-based electrolyte.</p

    The bioelectrical properties of bone tissue

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    Abstract Understanding the bioelectrical properties of bone tissue is key to developing new treatment strategies for bone diseases and injuries, as well as improving the design and fabrication of scaffold implants for bone tissue engineering. The bioelectrical properties of bone tissue can be attributed to the interaction of its various cell lineages (osteocyte, osteoblast and osteoclast) with the surrounding extracellular matrix, in the presence of various biomechanical stimuli arising from routine physical activities; and is best described as a combination and overlap of dielectric, piezoelectric, pyroelectric and ferroelectric properties, together with streaming potential and electro‐osmosis. There is close interdependence and interaction of the various electroactive and electrosensitive components of bone tissue, including cell membrane potential, voltage‐gated ion channels, intracellular signaling pathways, and cell surface receptors, together with various matrix components such as collagen, hydroxyapatite, proteoglycans and glycosaminoglycans. It is the remarkably complex web of interactive cross‐talk between the organic and non‐organic components of bone that define its electrophysiological properties, which in turn exerts a profound influence on its metabolism, homeostasis and regeneration in health and disease. This has spurred increasing interest in application of electroactive scaffolds in bone tissue engineering, to recapitulate the natural electrophysiological microenvironment of healthy bone tissue to facilitate bone defect repair

    Fracture prediction of tight sandstone reservoirs using outcrops and log curve-based extremum method: A case study of the Chang 7 Member of the Yanchang Formation in Block X, Ordos Basin

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    The lack of seismic data and special log data on the Chang 7 Member of the Yanchang Formation in Block X of the Ordos Basin poses a major challenge to the study of the development characteristics and identification of fractures that greatly influence on-site production. To overcome this obstacle, this study determined the macroscopic characteristics of fractures in the study area based on field outcrop profiles and indoor core observations. The results are as follows: (1) Fractures in the study area are dominated by regional fractures in weakly deformed structural areas, with three sets of fractures mainly occurring. Core observations show that fractures in the study area have high dip angles, small extensions, and small openings; (2) The vertical extended lengths of these fractures are significantly controlled by rock mechanical layers; (3) Fractures show three types of extended morphologies when meeting weak planes. Vertically, there is an exponential correlation between the sand body thickness and the fracture linear density. The argillaceous shale thickness has a logarithmic relationship to the fracture linear density when it is < 1 m and has an exponential relationship to the latter otherwise. The planar distribution of fractures is significantly affected by layer thickness and rock mechanical properties. Given the stable occurrence, high dip angles, and small extensions of regional fractures, this study highlighted the abnormal increase or decrease in log curve values of fracture segments by calculating the extrema of log curves. The purpose is to identify the locations and quantity of fractures using conventional log curves in the case of limited drilling data. This log curve-based extremum method enjoys a high resolution. For both coring and non-coring wells in the study area, there is a positive correlation between their fracture linear density determined based on the production segment thickness of vertical wells and their daily liquid yield in the first week of well test and pilot production. This result indicates that the method for identifying natural fractures proposed in this study is highly reliable. Moreover, this study provides key parameter controls for predicting the three-dimensional distribution of fractures. The understanding of the fracture spatial distribution is also a key external factor that affects the design and construction of horizontal well fracturing

    Role of YAP/TAZ in Cell Lineage Fate Determination and Related Signaling Pathways

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    The penultimate effectors of the Hippo signaling pathways YAP and TAZ, are transcriptional co-activator proteins that play key roles in many diverse biological processes, ranging from cell proliferation, tumorigenesis, mechanosensing and cell lineage fate determination, to wound healing and regeneration. In this review, we discuss the regulatory mechanisms by which YAP/TAZ control stem/progenitor cell differentiation into the various major lineages that are of interest to tissue engineering and regenerative medicine applications. Of particular interest is the key role of YAP/TAZ in maintaining the delicate balance between quiescence, self-renewal, proliferation and differentiation of endogenous adult stem cells within various tissues/organs during early development, normal homeostasis and regeneration/healing. Finally, we will consider how increasing knowledge of YAP/TAZ signaling might influence the trajectory of future progress in regenerative medicine.ISSN:2296-634

    The complete chloroplast genome of Coffea liberica (Gentianales: Rubiaceae)

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    Coffee is one of the most popular beverages around the world. As one of the best-known coffee species, Liberian coffee (Coffea liberica Bull ex Hiern 1876) has a high resistance to leaf rust, a devasting disease caused by Hemileia vastatrix. However, there are few reports on the systematic position and phylogenetic relationship of C. liberica at the chloroplast (cp) genome level. Thus, we successfully assembled its cp genome. The full length is 154,799 bp with a GC content of 37.48%. We have further annotated the cp genome and predicted 85 protein-coding genes together with 8 rRNAs and 37 tRNAs. Furthermore, a large single copy region (LSC), a small single copy region (SSC), an inverted repeat region a (IRa) and an inverted repeat region b (IRb) are identified with lengths of 84,868 bp, 18,121 bp, 25,905 bp and 25,905 bp, respectively. The phylogenetic tree indicates that C. liberica is closely related to C. canephora, which is consistent with a previous result obtained from genotyping‐by‐sequencing

    Metal-Sulfide Catalysts Derived from Lignosulfonate and their Efficient Use in Hydrogenolysis

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    Catalytic lignosulfonate valorization is hampered by the in situ liberation of sulfur that ultimately poisons the catalyst. To overcome this limitation, metal sulfide catalysts were developed that are able to cleave the C-O bonds of lignosulfonate and are resistant to sulfur poisoning. The catalysts were prepared by using the lignosulfonate substrate as a precursor to form well-dispersed carbon-supported metal (Co, Ni, Mo, CoMo, NiMo) sulfide catalysts. Following optimization of the reaction conditions employing a model substrate, the catalysts were used to generate guaiacyl monomers from lignosulfonate. The Co catalyst was able to produce 23.7 mg of 4-propylguaiacol per gram of lignosulfonate with a selectivity of 84 %. The catalysts operated in water and could be recycled and reused multiple times. Thus, it was demonstrated that an inexpensive, sulfur-tolerant catalyst based on an earth-abundant metal and lignosulfonate efficiently catalyzed the selective hydrogenolysis of lignosulfonate in water in the absence of additives

    Interaction between Porcine Alveolar Macrophage-Tang Cells and <i>Streptococcus suis</i> Strains of Different Virulence: Phagocytosis and Apoptosis

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    Streptococcus suis is an important swine bacterial pathogen that activates macrophages to secrete inflammatory cytokines. Primary porcine alveolar macrophages (PAMs) are inconvenient to obtain, but it is unknown whether immortalized PAM-Tang cells can replace them as a better cell model for the study of the interaction between S. suis and macrophages. In this study, the phagocytic integrity, polarization, and pro-inflammatory cytokine secretion of PAM-Tang cells were confirmed by live-cell imaging, electron microscopy, confocal microscopy, and ELISA. Interestingly, the S. suis serotype 9 avirulent strain W7119 induced higher levels of adhesion and pro-inflammatory cytokines in PAM-Tang cells than the S. suis serotype 2 virulent strain 700794. Prolonged incubation with S. suis caused more cytotoxic cell damage, and the virulent strain induced higher levels of cytotoxicity to PAM-Tang cells. The virulent strain also induced higher levels of apoptosis in PAM-Tang cells, as shown by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) assay. In addition, it is the first report of virulent and avirulent S. suis inducing PAM-Tang polarization towards pro-inflammatory M1 macrophages and p53- and caspase-dependent apoptosis in PAMs. Taken together, this study contributes to a better understand of interactions between macrophages and S. suis isolates of different virulence, and confirms that PAM-Tang cells provide a long-term, renewable resource for investigating macrophage infections with bacteria

    Genome-Wide Identification of <i>WRKY</i> Genes and Their Response to Cold Stress in <i>Coffea canephora</i>

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    WRKY transcription factors are known to play roles in diverse stress responses in plants. Low temperatures limit the geographic distribution of Coffea canephora Pierre ex A.Froehner. The WRKYs of C. canephora are still not well characterized, and the response of C. canephora WRKYs (CcWRKYs) under cold stress is still largely unknown. We identified 49 CcWRKYs from the C. canephora genome to gain insight into these mechanisms. These CcWRKYs were divided into three groups that were based on the conserved WRKY domains and zinc-finger structure. Gene expression analysis demonstrated that 14 CcWRKYs were induced during the cold acclimation stage, 17 CcWRKYs were preferentially upregulated by 4 &#176;C treatment, and 12 CcWRKYs were downregulated by cold stress. Subsequently, we carried out a genome-wide analysis to predict 14,513 potential CcWRKY target genes in C. canephora. These isolated genes were involved in multiple biological processes, and most of them could be grouped by the response to stimulus. Among the putative CcWRKY target genes, 235 genes were categorized into response to the cold process, including carbohydrate metabolic, lipid metabolic, and photosynthesis process-related genes. Furthermore, the qRT-PCR and correlation analysis indicated that CcWRKY might control their putative targets that respond to cold stress. These results provide a basis for understanding the molecular mechanism for CcWRKY-mediated cold responses

    Anaerobic germination of green coffee beans: A novel strategy to improve the quality of commercial Arabica coffee

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    This study aimed to improve the brewing quality of commercial Arabica coffee through anaerobic germination. Changes in important compounds and cupping scores of germination roasting coffee with different germination degrees were investigated by 1H NMR, HS-SPME-GC-MS and sensory analysis. Statistical analysis of multivariate analysis results indicated that 6 water-soluble chemical components and 8 volatile chemical components have the potential to be markers of germinated roasting coffee. In addition, germination significantly reduced caffeine content and acrylamide formation in roasted coffee. Sensory analysis according to the Specialty Coffee Association (SCA) cupping protocol demonstrated that anaerobic germination modified flavor attributes, improved the quality, and increased sensory scores. Furthermore, anaerobic sprouting increased fruity descriptors, but over-sprouting did not improve overall attributes while producing both fermentative and vegetable descriptors. Therefore, suitable anaerobic germination of green coffee beans can be used as a new strategy to improve the flavor of commercial Arabica coffee
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