The effect of surface treatment using silanes on the frost durability is investigated on both laboratory and field specimens in an accelerated laboratory test. Measurements include moisture uptake ...during the pre-saturation and F-T stages, cumulative mass loss and internal bulk cracking under frost salt/water exposure. It is found silane treatment substantially reduces surface scaling, but cannot prevent bulk moisture uptake or the occurrence of the internal frost damage when concrete is insufficiently air entrained. Salt scaling is dominated by the capillary suction process in the thin surface region under freezing which can be curtailed by the pore lining effect from silanes creating a hydrophobic barrier to the ingress of external liquid. This in turn suppresses ice growth in the surface region, evidenced by the complete elimination of sub-freezing dilation in a length-change measurement of small-scale concrete specimens with surface treatment. However, internal frost damage is controlled by the universal degree of pore saturation which in turn is dependent on the bulk moisture uptake.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Although ultra high-performance concrete (UHPC) has great performance in strength and durability, it has a disadvantage in the environmental aspect; it contains a large amount of cement that is ...responsible for a high amount of CO
emissions from UHPC. Supplementary cementitious materials (SCMs), industrial by-products or naturally occurring materials can help relieve the environmental burden by reducing the amount of cement in UHPC. This paper reviews the effect of SCMs on the properties of UHPC in the aspects of material properties and environmental impacts. It was found that various kinds of SCMs have been used in UHPC in the literature and they can be classified as slag, fly ash, limestone powder, metakaolin, and others. The effects of each SCM are discussed mainly on the early age compressive strength, the late age compressive strength, the workability, and the shrinkage of UHPC. It can be concluded that various forms of SCMs were successfully applied to UHPC possessing the material requirement of UHPC such as compressive strength. Finally, the analysis on the environmental impact of the UHPC mix designs with the SCMs is provided using embodied CO
generated during the material production.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The interaction between a salt solution and ice formation in capillary pores might provide new insight into the salt frost scaling process. To accomplish this small prismatic specimens ...(10mm×10mm×90mm) were cut from air-entrained concrete, dried at 50°C until constant weight, then immersed in sodium chloride (NaCl) solutions of different concentrations (0%, 3%, 9% and 12%) until they reached full capillary saturation. They were then subjected to a freeze–thaw (F–T) cycle in a high resolution low temperature dilatometer (LTD) with the surface temperature and uniaxial length-change continuously monitored. Internal saturation of capillary pores with increasing salt solutions is found to have a profound effect on the F–T response including the temperature rise and instant dilation associated with ice nucleation. It is concluded that salt ions retard ice formation and the effect of ice-growth on pore expansion during an F–T cycle. The presence of salt ions in the concrete pores and surface liquid has a counter-balancing effect on specimen length-change associated with ice-growth, which may provide one possible explanation for the pessimum salt concentration effect. The extent of surface scaling is also affected by the intrinsic capillary transport property (i.e., sorptivity) of the porous cementitious binder. Salt scaling is exacerbated in concretes with increasing sorptivity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Ultra-high performance concrete (UHPC) achieves extraordinary strength characteristics through optimization of the particle packing density of the cementitious matrix. The dense matrix also promotes ...exceptional durability properties and is arguably the biggest benefit of the material. A durable concrete enables structures to last longer, reduces the cost of maintenance and helps achieve a significantly more sustainable infrastructure. To assess the durability of UHPC, the performance of several non-proprietary blends are investigated by assessing the materials' resistance to freeze-thaw cycles, ingress of chlorides as well as the presence and distribution of air voids. The main experimental variables are cement type and the quantity of silica powder, which varies from 0% to 25% of the cement weight. All mixes displayed negligible chloride ion penetration and high resistance to freeze-thaw with mass loss well below the limit in over 60 cycles of freeze-thaw. Analysis of the test data indicates that the silica powder content has little influence on performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Viruses cause serious pathogenic contamination that severely affects the environment and human health. Cold atmospheric-pressure plasma efficiently inactivates pathogenic bacteria; however, the ...mechanism of virus inactivation by plasma is not fully understood. In this study, surface plasma in argon mixed with 1% air and plasma-activated water was used to treat water containing bacteriophages. Both agents efficiently inactivated bacteriophages T4, Φ174, and MS2 in a time-dependent manner. Prolonged storage had marginal effects on the antiviral activity of plasma-activated water. DNA and protein analysis revealed that the reactive species generated by plasma damaged both nucleic acids and proteins, consistent with the morphological examination showing that plasma treatment caused the aggregation of bacteriophages. The inactivation of bacteriophages was alleviated by the singlet oxygen scavengers, demonstrating that singlet oxygen played a primary role in this process. Our findings provide a potentially effective disinfecting strategy to combat the environmental viruses using cold atmospheric-pressure plasma and plasma-activated water.
Contamination with pathogenic and infectious viruses severely threatens human health and animal husbandry. Current methods for disinfection have different disadvantages, such as inconvenience and contamination of disinfection by-products (e.g., chlorine disinfection). In this study, atmospheric surface plasma in argon mixed with air and plasma-activated water was found to efficiently inactivate bacteriophages, and plasma-activated water still had strong antiviral activity after prolonged storage. Furthermore, it was shown that bacteriophage inactivation was associated with damage to nucleic acids and proteins by singlet oxygen. An understanding of the biological effects of plasma-based treatment is useful to inform the development of plasma into a novel disinfecting strategy with convenience and no by-product.
Water exchange and migration of superabsorbent polymers (SAP) in cement paste is a very complicated process and governs the effectiveness of internal curing in concrete. The early state of SAP in ...real pore fluids was investigated under different water-cement ratios and hydration time. It is found out water absorption of SAP is not a constant value, but varies depending on these two factors. The absorption and desorption behavior of SAP is demonstrated in the shifted hydration peak location and the water-rich region around the SAP gels. The water exchange between SAP and cement pastes is quantified by the measured water content with time, from which a characteristic “two-stage desorption” driven by osmotic pressure and humidity gradient, respectively, is identified. The humidity-controlled desorption that is beneficial for internal curing is calculated. It is indicated the internal curing efficiency could be improved by shortening the osmotic stage and prolonging the humidity stage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Understanding physiological and pathological processes in the brain requires tracking the reversible changes in chemical signals with long‐term stability. We developed a new anti‐biofouling ...microfiber array to real‐time quantify extracellular Ca2+ concentrations together with neuron activity across many regions in the mammalian brain for 60 days, in which the signal degradation was < ca. 8 %. The microarray with high tempo‐spatial resolution (ca. 10 μm, ca. 1.3 s) was implanted into 7 brain regions of free‐moving mice to monitor reversible changes of extracellular Ca2+ upon ischemia‐reperfusion processes. The changing sequence and rate of Ca2+ in 7 brain regions were different during the stroke. ROS scavenger could protect Ca2+ influx and neuronal activity after stroke, suggesting the significant influence of ROS on Ca2+ overload and neuron death. We demonstrated this microarray is a versatile tool for investigating brain dynamic during pathological processes and drug treatment.
An anti‐biofouling microfiber array was created to real‐time tracking and reversibly quantifying of extracellular concentration of Ca2+ together with neuron activity across many regions in freely moving mammalian brain for 60 days. The changing sequence and rate of Ca2+ in 7 brain regions were different during the stroke, and ROS scavenger could protect Ca2+ influx and neuronal activity after stroke.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Advanced microscopy enables us to acquire quantities of time-lapse images to visualize the dynamic characteristics of tissues, cells or molecules. Microscopy images typically vary in signal-to-noise ...ratios and include a wealth of information which require multiple parameters and time-consuming iterative algorithms for processing. Precise analysis and statistical quantification are often needed for the understanding of the biological mechanisms underlying these dynamic image sequences, which has become a big challenge in the field. As deep learning technologies develop quickly, they have been applied in bioimage processing more and more frequently. Novel deep learning models based on convolution neural networks have been developed and illustrated to achieve inspiring outcomes. This review article introduces the applications of deep learning algorithms in microscopy image analysis, which include image classification, region segmentation, object tracking and super-resolution reconstruction. We also discuss the drawbacks of existing deep learning-based methods, especially on the challenges of training datasets acquisition and evaluation, and propose the potential solutions. Furthermore, the latest development of augmented intelligent microscopy that based on deep learning technology may lead to revolution in biomedical research.
•Deep learning-based microscopy image analysis is of great significance for biomedical researches.•The applications of deep learning in image classification, segmentation, tracking and reconstruction are summarized.•The challenges in deep learning (e.g. lack of annotated public datasets) are discussed.•Augmented intelligent microscopy that based on deep learning technology may lead to revolution in biomedical research.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Repetitive control (RC) with linear phase lead compensation provides a simple but very effective control solution for any periodic signal with a known period. Multirate repetitive control (MRC) with ...a downsampling rate can reduce the need of memory size and computational cost, and then leads to a more feasible design of the plug-in RC systems in practical applications. However, with fixed sampling rate, both MRC and its linear phase lead compensator are sensitive to the ratio of the sampling frequency to the frequency of interested periodic signals: 1) MRC might fails to exactly compensate the periodic signal in the case of a fractional ratio; 2) linear phase lead compensation might fail to enable MRC to achieve satisfactory performance in the case of a low ratio. In this paper, a universal fractional-order design of linear phase lead compensation MRC is proposed to tackle periodic signals with high accuracy, fast dynamic response, good robustness, and cost-effective implementation regardless of the frequency ratio, which offers a unified framework for housing various RC schemes in extensive engineering application. An application example of programmable ac power supply is explored to comprehensively testify the effectiveness of the proposed control scheme.
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