In this study, rice husk ash (RHA)-based reactive filler was used in ultra-high performance concrete (UHPC) to improve mechanical properties without heat-treatment. This strategy replaces inert ...quartz filler with the reactive RHA filler, to increase the amorphous silica content while maintaining the physical role of the micron-sized quartz filler. Due to the high porosity of RHA, internal curing is effective, which promotes the hydration reaction over a long period of time. Experimental results show an outstanding strength around 200 MPa after 91 days, under ambient conditions (20 °C and 60% relative humidity). This was possible due to the promotion of pozzolanic reaction by additional water and amorphous silica provided by the porous (i.e., internal curing effect) and reactive filler, respectively; hence, the volume of capillary pores was reduced. The result reported herein will further promote the utilization of agricultural byproduct for the development of reactive RHA-based construction materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A new modified tea-bag method with various cement-based solutions is used to investigate the absorption kinetics of superabsorbent polymer (SAP) in concrete with low water to cement ratio (W/C). It ...includes a centrifugal process to efficiently remove the excess solution that can cause inaccurate absorption measurements. Various cement-based artificial pore solutions are prepared by dissolving ions in cement filtrates and considering the influence of silica fumes and polycarboxylate-ether type superplasticizers. Depending on the monovalent ion concentrations under the given Ca concentration of the filtrate, the absorption kinetics is drastically altered. This result underlines the risk of underestimating the absorption capacity of SAP in concrete. The suggested method and prepared solutions can be used to reasonably and efficiently determine the amount of required extra water for internal curing. Furthermore, the investigated ion-dependent characteristics will enhance our understanding of the absorption kinetics and contribute to the development of hydrogel products for concrete.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Mesenchymal stem cell (MSC) is a promising tool for the therapy of immune disorders. However, their efficacy and mechanisms in treating allergic skin disorders are less verified. We sought to ...investigate the therapeutic efficacy of human umbilical cord blood‐derived MSCs (hUCB‐MSCs) against murine atopic dermatitis (AD) and to explore distinct mechanisms that regulate their efficacy. AD was induced in mice by the topical application of Dermatophagoides farinae. Naïve or activated‐hUCB‐MSCs were administered to mice, and clinical severity was determined. The subcutaneous administration of nucleotide‐binding oligomerization domain 2 (NOD2)‐activated hUCB‐MSCs exhibited prominent protective effects against AD, and suppressed the infiltration and degranulation of mast cells (MCs). A β‐hexosaminidase assay was performed to evaluate the effect of hUCB‐MSCs on MC degranulation. NOD2‐activated MSCs reduced the MC degranulation via NOD2‐cyclooxygenase‐2 signaling. In contrast to bone marrow‐derived MSCs, hUCB‐MSCs exerted a cell‐to‐cell contact‐independent suppressive effect on MC degranulation through the higher production of prostaglandin E2 (PGE2). Additionally, transforming growth factor (TGF)‐β1 production from hUCB‐MSCs in response to interleukin‐4 contributed to the attenuation of MC degranulation by downregulating FcεRI expression in MCs. In conclusion, the subcutaneous application of NOD2‐activated hUCB‐MSCs can efficiently ameliorate AD, and MSC‐derived PGE2 and TGF‐β1 are required for the inhibition of MC degranulation. Stem Cells 2015;33:1254–1266
•Two experimental methods (3D μ-CT and MIP) were used to analyze a wide range of pores in UHPC.•The pore structure of UHPC was altered by superabsorbent polymer (SAP)-based internal curing and ...heat-treatment.•A linear relationship was found between the compressive strength of UHPC and the total porosity determined by MIP.•The effect of heat-treatment was diminished due to the internal curing effect.
The addition of superabsorbent polymer (SAP) mainly has two opposite effects on the pore structure of ultra-high performance concrete (UHPC): the densification of microstructure due to internal curing (IC) and the increase of large voids by swollen SAP particles. To further elucidate these effects on various properties of UHPC, the pore structure of internally cured UHPC is studied in a wide range of 3 nm–10 mm (in diameter), by two methods of micro X-ray computed tomography (μ-CT) and mercury intrusion porosimetry (MIP). Owing to the different measurable pore scale, each method provides different total porosity and pore size distribution. The SAP voids significantly increase the porosity in the size range of 267 µm–2.7 mm, whereas IC makes the pore structure finer within 3–100 nm. In particular, the microstructural change due to the IC has a more decisive influence on the compressive strength than larger SAP voids. In addition, it is discovered that the positive effect of heat-treatment (HT) for UHPC is diminished due to the applied IC. The IC and HT have to share limited amounts of raw materials and space necessary to promote the hydration reaction. However, the IC consumes parts of them before the HT does, thereby limits conventional positive effect of the HT.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•A novel piezoelectric flag orientation with enhanced energy harvesting capability.•Easy flapping tunability and flapping at a wide range of wind speed.•High electrical energy ...generation from ambient wind with fluctuating conditions.•Self-powered device using ambient wind energy.
The paper describes an experimental study of wind energy harvesting by self-sustained oscillations (flutter) of a flexible piezoelectric membrane fixed in a novel orientation called the “inverted flag”. We conducted parametric studies to evaluate the influence of geometrical parameters of the flag on the flapping behavior and the resulting energy output. We have demonstrated the capability for inducing aero-elastic flutter in a desired wind velocity range by simply tuning the geometrical parameters of the flag. A peak electrical power of ∼5.0mW/cm3 occurred at a wind velocity of 9m/s. Our devices showed sustained power generation (∼0.4mW/cm3) even in low-wind speed regimes (∼3.5m/s) suitable for ambient wind energy harvesting. We also conducted outdoor experiments and harvested ambient wind energy to power a temperature sensor without employing a battery for energy storage. Moreover, a self-aligning mechanism to compensate for changing wind directions was incorporated and resulted in an increase in the temperature sensor data output by more than 20 times. These findings open new opportunities for self-powered devices using ambient wind energy with fluctuating conditions and low speed regimes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In this study, the interdependent relationships among hydration reaction, internal relative humidity (RH), and strength of internally cured ultra-high performance concrete (UHPC) were investigated, ...to emphasize the importance of drying on superabsorbent polymer-based internal curing (IC). Experiments showed that the self-desiccation of UHPC cannot be prevented by external curing, such as water curing, but can be prevented by IC. Although the desiccation and resulting shrinkage of UHPC were effectively mitigated by the IC, a slow strength development was found when maintaining a high internal RH. Under water-curing conditions, the internally cured UHPCs showed 12–17% lower strength at 28 days compared with the reference sample. However, the results were 0–1% when exposed to dry air (RH 60%) between 7 and 28 days, showing accelerated external drying. The results show that the early-age shrinkage-related problem of UHPC can be fundamentally resolved, without a negative effect on strength, by controlling the drying period.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
: To quantify the effects of midline-related landmark identification on midline deviation measurements in posteroanterior (PA) cephalograms using a cascaded convolutional neural network (CNN).
: A ...total of 2,903 PA cephalogram images obtained from 9 university hospitals were divided into training, internal validation, and test sets (n = 2,150, 376, and 377). As the gold standard, 2 orthodontic professors marked the bilateral landmarks, including the frontozygomatic suture point and latero-orbitale (LO), and the midline landmarks, including the crista galli, anterior nasal spine (ANS), upper dental midpoint (UDM), lower dental midpoint (LDM), and menton (Me). For the test, Examiner-1 and Examiner-2 (3-year and 1-year orthodontic residents) and the Cascaded-CNN models marked the landmarks. After point-to-point errors of landmark identification, the successful detection rate (SDR) and distance and direction of the midline landmark deviation from the midsagittal line (ANS-mid, UDM-mid, LDM-mid, and Me-mid) were measured, and statistical analysis was performed.
: The cascaded-CNN algorithm showed a clinically acceptable level of point-to-point error (1.26 mm vs. 1.57 mm in Examiner-1 and 1.75 mm in Examiner-2). The average SDR within the 2 mm range was 83.2%, with high accuracy at the LO (right, 96.9%; left, 97.1%), and UDM (96.9%). The absolute measurement errors were less than 1 mm for ANS-mid, UDM-mid, and LDM-mid compared with the gold standard.
: The cascaded-CNN model may be considered an effective tool for the auto-identification of midline landmarks and quantification of midline deviation in PA cephalograms of adult patients, regardless of variations in the image acquisition method.
This study investigated the effect of the incorporation of the supplementary cementitious material (SCM) of hydrophobic silica and silica fume on the mechanical properties and hydration behavior of ...ordinary Portland cement (OPC). Silica fume is a well-known SCM owing to its good compatibility with OPC by providing seeding sites for nucleation and subsequent acceleration and reactive silica for pozzolanic reaction. This study revealed that mortars containing hydrophobic silica developed higher compressive strength than pure mortar and mortar with regular silica fume during all curing ages. Furthermore, it was confirmed that it contributed to produce more hydration products and consume more portlandite, implying its acceleration and pozzolanic reaction, respectively. Although its particle size is larger than that of silica fume, its hydrophobicity accelerated the hydration reaction due to the better dispersion of OPC in the system, which leads to more exposure of cement particles to available water. These effects could cause higher dissolution of the particles and faster interfacial precipitation of hydration products. Therefore, the hydrophobic silica outperformed the seeding-based acceleration effect of silica fume.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Reactive microglia are a major pathological feature of Alzheimer's disease (AD). However, the exact role of microglia in AD pathogenesis is still unclear. Here, using metabolic profiling, we found ...that exposure to amyloid-β triggers acute microglial inflammation accompanied by metabolic reprogramming from oxidative phosphorylation to glycolysis. It was dependent on the mTOR-HIF-1α pathway. However, once activated, microglia reached a chronic tolerant phase as a result of broad defects in energy metabolisms and subsequently diminished immune responses, including cytokine secretion and phagocytosis. Using genome-wide RNA sequencing and multiphoton microscopy techniques, we further identified metabolically defective microglia in 5XFAD mice, an AD mouse model. Finally, we showed that metabolic boosting with recombinant interferon-γ treatment reversed the defective glycolytic metabolism and inflammatory functions of microglia, thereby mitigating the AD pathology of 5XFAD mice. Collectively, metabolic reprogramming is crucial for microglial functions in AD, and modulating metabolism might be a new therapeutic strategy for AD.
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•Aβ induces metabolic reprogramming of microglia from OXPHOS to glycolysis•Metabolic reprogramming of microglia is dependent on the mTOR-HIF-1α pathway•Chronic exposure to Aβ induces metabolic defects of microglia•Metabolic boosting with IFN-γ restores immunological function of microglia
Baik et al. report that amyloid-β acutely triggers microglial activation and metabolic reprogramming from OXPHOS to glycolysis. However, chronic exposure to amyloid-β induces overall metabolic defects in microglia in a model of Alzheimer's disease. Treatment with IFN-γ restores glycolytic metabolism and immunological function of microglia, suggesting that modulation of microglial metabolism may be a potential therapeutic strategy.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The shrinkage and cracking risk of heat-treated ultra-high performance concrete (UHPC) can be mitigated by using the superabsorbent polymer (SAP)-based internal curing method. The heat treatment (HT) ...accelerates the hydration reaction and resulting self-desiccation of UHPC; consequently, the UHPC experiences severe shrinkage during the HT. This study experimentally demonstrates that the shrinkage is effectively resolved by adopting the SAP-based internal curing method during the HT period as well as early-ages. This method also reduces the strain rate resulting from dimensional change, without showing an increase in drying shrinkage. The accurately conducted experiments herein can help to better understand the shrinkage characteristics of heat-treated UHPC and broaden the application of various internal curing agents.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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