79 research outputs found

    Effect of the Sodium Silicate Modulus and Slag Content on Fresh and Hardened Properties of Alkali-Activated Fly Ash/Slag

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    This paper presents the results of an experimental study performed to investigate the effect of activator modulus (SiO2/Na2O) and slag addition on the fresh and hardened properties of alkali-activated fly ash/slag (AAFS) pastes. Four activator moduli (SiO2/Na2O), i.e., 0.0, 1.0, 1.5, and 2.0, and five slag-to-binder ratios, i.e., 0, 0.3, 0.5, 0.7, 1.0, were used to prepare AAFS mixtures. The setting time, flowability, heat evolution, compressive strength, microstructure, and reaction products of AAFS pastes were studied. The results showed that the activator modulus and slag content had a combined effect on the setting behavior and workability of AAFS mixtures. Both the activator modulus and slag content affected the types of reaction products formed in AAFS. The coexistence of N-A-S-H gel and C-A-S-H gel was identified in AAFS activated with high pH but low SiO2 content (low modulus). C-A-S-H gel had a higher space-filling ability than N-A-S-H gel. Thus, AAFS with higher slag content had a finer pore structure and higher heat release (degree of reaction), corresponding to a higher compressive strength. The dissolution of slag was more pronounced when NaOH (modulus of 0.0) was applied as the activator. The use of Na2SiO3 as activator significantly refined the pores in AAFS by incorporating soluble Si in the activator, while further increasing the modulus from 1.5 to 2.0 prohibited the reaction process of AAFS, resulting in a lower heat release, coarser pore structure, and reduced compressive strength. Therefore, in view of the strength and microstructure, the optimum modulus is 1.5

    Ponder: Point Cloud Pre-training via Neural Rendering

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    We propose a novel approach to self-supervised learning of point cloud representations by differentiable neural rendering. Motivated by the fact that informative point cloud features should be able to encode rich geometry and appearance cues and render realistic images, we train a point-cloud encoder within a devised point-based neural renderer by comparing the rendered images with real images on massive RGB-D data. The learned point-cloud encoder can be easily integrated into various downstream tasks, including not only high-level tasks like 3D detection and segmentation, but low-level tasks like 3D reconstruction and image synthesis. Extensive experiments on various tasks demonstrate the superiority of our approach compared to existing pre-training methods.Comment: Project page: https://dihuang.me/ponder

    CoDeF: Content Deformation Fields for Temporally Consistent Video Processing

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    We present the content deformation field CoDeF as a new type of video representation, which consists of a canonical content field aggregating the static contents in the entire video and a temporal deformation field recording the transformations from the canonical image (i.e., rendered from the canonical content field) to each individual frame along the time axis.Given a target video, these two fields are jointly optimized to reconstruct it through a carefully tailored rendering pipeline.We advisedly introduce some regularizations into the optimization process, urging the canonical content field to inherit semantics (e.g., the object shape) from the video.With such a design, CoDeF naturally supports lifting image algorithms for video processing, in the sense that one can apply an image algorithm to the canonical image and effortlessly propagate the outcomes to the entire video with the aid of the temporal deformation field.We experimentally show that CoDeF is able to lift image-to-image translation to video-to-video translation and lift keypoint detection to keypoint tracking without any training.More importantly, thanks to our lifting strategy that deploys the algorithms on only one image, we achieve superior cross-frame consistency in processed videos compared to existing video-to-video translation approaches, and even manage to track non-rigid objects like water and smog.Project page can be found at https://qiuyu96.github.io/CoDeF/.Comment: Project Webpage: https://qiuyu96.github.io/CoDeF/, Code: https://github.com/qiuyu96/CoDe

    Identification of a Potential miRNA–mRNA Regulatory Network Associated With the Prognosis of HBV-ACLF

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    BackgroundHepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is a life-threatening disease with a high mortality rate; the systemic inflammatory response plays a vital role in disease progression. We aimed to determine if a miRNA–mRNA co-regulatory network exists in the peripheral blood mononuclear cells (PBMCs) of HBV-ACLF patients, which might be important for prognosis.MethodsTranscriptome-wide microRNA (miRNA) and mRNA microarrays were used to define the miRNA and mRNA expression profiles of the PBMCs of HBV-ACLF patients in a discovery cohort. The targets of the miRNAs were predicted. We built a miRNA-mRNA regulatory network through bioinformatics analysis, and used quantitative real-time polymerase chain reaction (qRT-PCR) to assess the importance of candidate miRNAs and mRNAs. We also assessed the direct and transcriptional regulatory effects of miRNAs on target mRNAs using a dual-luciferase reporter assay.ResultsThe miRNA/mRNA PBMC expression profiles of the discovery cohort, of whom eight survived and eight died, revealed a prognostic interactive network involving 38 miRNAs and 313 mRNAs; this was constructed by identifying the target genes of the miRNAs. We validated the expression data in another cohort, of whom 43 survived and 35 died; miR-6840-3p, miR-6861-3p, JADE2, and NR3C2 were of particular interest. The levels of miR-6840-3p and miR-6861-3p were significantly increased in the PBMCs of the patients who died, and thus predicted prognosis (areas under the curve values = 0.665 and 0.700, respectively). The dual-luciferase reporter assay indicated that miR-6840-3p directly targeted JADE2.ConclusionWe identified a prognostic miRNA-mRNA co-regulatory network in the PBMCs of HBV-ACLF patients. miR-6840-3p-JADE2 is a potential miRNA–mRNA pair contributing to a poor prognosis

    An Inhibitory Effect of Extracellular Ca2+ on Ca2+-Dependent Exocytosis

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    Aim: Neurotransmitter release is elicited by an elevation of intracellular Ca 2+ concentration ([Ca 2+] i). The action potential triggers Ca 2+ influx through Ca 2+ channels which causes local changes of [Ca 2+] i for vesicle release. However, any direct role of extracellular Ca 2+ (besides Ca 2+ influx) on Ca 2+-dependent exocytosis remains elusive. Here we set out to investigate this possibility on rat dorsal root ganglion (DRG) neurons and chromaffin cells, widely used models for studying vesicle exocytosis. Results: Using photolysis of caged Ca 2+ and caffeine-induced release of stored Ca 2+, we found that extracellular Ca 2+ inhibited exocytosis following moderate [Ca 2+]i rises (2–3 mM). The IC50 for extracellular Ca 2+ inhibition of exocytosis (ECIE) was 1.38 mM and a physiological reduction (,30%) of extracellular Ca 2+ concentration ([Ca 2+]o) significantly increased the evoked exocytosis. At the single vesicle level, quantal size and release frequency were also altered by physiological [Ca 2+] o. The calcimimetics Mg 2+,Cd 2+, G418, and neomycin all inhibited exocytosis. The extracellular Ca 2+-sensing receptor (CaSR) was not involved because specific drugs and knockdown of CaSR in DRG neurons did not affect ECIE. Conclusion/Significance: As an extension of the classic Ca 2+ hypothesis of synaptic release, physiological levels of extracellular Ca 2+ play dual roles in evoked exocytosis by providing a source of Ca 2+ influx, and by directly regulatin

    A large genome-wide association study of age-related macular degeneration highlights contributions of rare and common variants.

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    This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/ng.3448Advanced age-related macular degeneration (AMD) is the leading cause of blindness in the elderly, with limited therapeutic options. Here we report on a study of >12 million variants, including 163,714 directly genotyped, mostly rare, protein-altering variants. Analyzing 16,144 patients and 17,832 controls, we identify 52 independently associated common and rare variants (P < 5 × 10(-8)) distributed across 34 loci. Although wet and dry AMD subtypes exhibit predominantly shared genetics, we identify the first genetic association signal specific to wet AMD, near MMP9 (difference P value = 4.1 × 10(-10)). Very rare coding variants (frequency <0.1%) in CFH, CFI and TIMP3 suggest causal roles for these genes, as does a splice variant in SLC16A8. Our results support the hypothesis that rare coding variants can pinpoint causal genes within known genetic loci and illustrate that applying the approach systematically to detect new loci requires extremely large sample sizes.We thank all participants of all the studies included for enabling this research by their participation in these studies. Computer resources for this project have been provided by the high-performance computing centers of the University of Michigan and the University of Regensburg. Group-specific acknowledgments can be found in the Supplementary Note. The Center for Inherited Diseases Research (CIDR) Program contract number is HHSN268201200008I. This and the main consortium work were predominantly funded by 1X01HG006934-01 to G.R.A. and R01 EY022310 to J.L.H

    Surface Charge Properties of Marble Powder and its Effect on the Formation of Hydrates in Cement Paste

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    Replacing part of cement with waste stone powder can reduce the use of cement, thus reducing energy consumption and CO2 emission. Different stone powders affect the properties of cement-based materials differently. It is important to clarify the effect of the surface properties of the stone powder on the properties of cement-based materials. In this paper, the charge properties of marble powder and its effect on the formation of hydrates were investigated. Zeta potential was used to study the charge properties of the marble surface. Parallelly, the morphology of hydrates on the surface of the cement and marble particles at a very early hydration age was observed by using SEM. Finally, the influence of the surface charge properties of the marble particles on the formation of hydration products of cement was discussed. The results showed that the marble particles have specific adsorption of Ca2+ (chemical adsorption). Therefore, the marble particles in the simulated solution can adsorb a large amount of Ca2+, thus achieving a high potential value and facilitating the formation of hydrates on their surface. However, the adsorption of Ca2+ towards the surface of the cement particle is driven by a relatively weak electrostatic force. Compared with the marble particles, less Ca2+ ions are adsorbed, and thus, fewer hydrates are formed on the surface of cement particles
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