•Influencing factors on recycled aggregate quality are discussed.•Influence of recycled aggregate quality on concrete properties is overviewed.•Properties of parent concrete affect the properties of ...recycled aggregate concrete.•Optimal replacement levels based on recycled aggregate quality are discussed.
Considering that a lot of energy is consumed to produce high quality recycled aggregate, efficient use of each quality of recycled aggregate is required. Therefore, this study overviews the literature on the effect of recycled aggregate quality on the mechanical properties of concrete. Some discussion of the characteristics of recycled aggregate and factors affecting the quality of recycled aggregate has been included. Data on the fresh and hardened properties of recycled aggregate concrete mixed with each quality were reviewed. This article can provide insight into the effective utilization of recycled aggregate.
Abstract
Osteocytes are mechanosensory commander cells to regulate bone remodeling throughout the lifespan. While the osteocytes are known as terminally differentiated cells derived from mesenchymal ...stem cells, the detailed mechanisms of osteocyte differentiation remain unclear. In this study, we fabricated 3D self-organized spheroids using human mesenchymal stem cells (MSCs). Under the osteogenesis induction medium, the spheroid culture model exerted the osteocyte-likeness within 2 days compared to a conventional 2D monolayer model. Moreover, we showed that an inhibition of actin polymerization in the spheroid further up-regulated the osteocyte gene expressions. Notably, we represented that the cell condensed condition acquired in the 3D spheroid culture model determined a differentiation fate of MSCs to osteocytes. Taken together, we suggest that our self-organized spheroid model can be utilized as a new in vitro model to represent the osteocyte and to recapitulate an in vitro ossification process.
The abundance of fluorescent dissolved organic matter (FDOM) in the surface ocean plays a critical role in the growth of marine microorganisms and corals by affecting the optical properties (i.e., ...the penetration of UV radiation) of seawater. In general, it is known that rivers are the main source of FDOM to surface ocean waters. Here, however, we show that the concentrations of FDOM in coastal seawater off a volcanic island, Jeju, Korea, are dependent primarily on submarine groundwater discharge (SGD). Based on a significant correlation between
Rn and salinity in seawater, fresh groundwater was found to be the main source of groundwater as well as fresh water in the bay. The addition of dissolved organic carbon (DOC) and protein-like FDOM to the bay via SGD was generally negligible or negative. However, SGD enhanced the inventory of humic-like FDOM (FDOM
) in seawater by 2-3 times over all seasons, with conservative behavior of FDOM
in bay seawater. These results suggest that SGD-driven fluxes of FDOM regulate its inventory in seawater and consequently play a significant role in determining the optical properties of coastal waters off islands and associated coastal ecosystems (i.e., corals).
The distribution of fluorescent dissolved organic matter (FDOM) in the East Sea (Sea of Japan) was examined by excitation‐emission matrix spectroscopy with parallel factor analysis (PARAFAC). ...Humic‐like FDOM (FDOMH) increased with depth and was significantly correlated with Apparent Oxygen Utilization (AOU), indicating that FDOMH in the deep water is mainly produced by oxidation of organic matter. In addition, a surprisingly large excess of FDOMH relative to that expected from the observed AOU was found from 1000 m to the bottom (up to 3500 m). Based on the high‐resolution geographical distribution and characteristics of FDOM in the East Sea, we conclude that this excess likely originates from anaerobic FDOMH production in subsurface bottom sediments. This FDOMH flux accounts for 8–15% of the total FDOM production in the water column. Our results suggest that anaerobic activities in subsurface sediments are an important hidden source of FDOM in the ocean.
Key Points
Excess FDOM was observed in the deep East Sea (Sea of Japan)
FDOM is produced by an anaerobic process in subsurface bottom sediments
Excess FDOM fluxes account for about 10% of the deep‐sea CDOM production
Osteocytes play an important role to modulate the bone remodeling and are also known as terminally differentiated cells originated from the osteoblast precursor cells, but its differentiation ...mechanism remains unclear. Since an efficient in vitro method to evoke the osteocyte differentiation from the osteoblast precursor cells has not been established, we conducted the comparative gene expression analysis for mouse pre-osteoblast MC3T3-E1 cells in order to elucidate the key factors to induce the osteocyte differentiation from the pre-osteoblast cells. In this study, we prepared four different culture environments by modulating their cell-substrate interaction and cell–cell interaction; (i) low and (ii) high cell density on the adhesive culture models, and (iii) low and (iv) high cell density on the non-adhesive floating culture models. By comparing these conditions in terms of cell-substrate and cell–cell interaction, we showed that the elimination of cell-substrate interaction under non-adhesive floating culture greatly up-regulated the gene expression of osteocyte markers in the pre-osteoblast cells. Moreover, the presence of moderate cell–cell interaction in the non-adhesive spheroid culture further enhanced the up-regulation of osteocyte markers for the pre-osteoblast cells. The results altogether suggest the most appropriate culture environment to induce the in vitro osteocyte differentiation of pre-osteoblast cells.
Image processing can be used to extract meaningful optical results from images. Here, from images of plasmonic structures, we combined convolutional neural networks with recurrent neural networks to ...extract the absorption spectra of structures. To provide the data required for the model, we performed 100,000 simulations with similar setups and random structures. In designing this deep network, we created a model that can predict the absorption response of any structure with a similar setup. We used convolutional neural networks to collect spatial information from the images, and then, we used that data and recurrent neural networks to teach the model to predict the relationship between the spatial information and the absorption spectrum. Our results show that this image processing method is accurate and can be used to replace time- and computationally-intensive numerical simulations. The trained model can predict the optical results in less than a second without the need for a strong computing system. This technique can be easily extended to cover different structures and extract any other optical properties.
Academic burnout has a negative effect on learning outcomes of nursing students. Factors affecting academic burnout may differ depending on whether or not they have experience in clinical practice ...and identifying these differences would be necessary to seek for strategies to lower academic burnout of nursing students. This study aimed to determine the effects of stress, depression, and anxiety on academic burnout according to the clinical practice experience of nursing students.
Data were collected from 171 female nursing students in South Korea. Self-report questionnaires from 83 participants without clinical practice experience and 88 with clinical practice experience were analyzed using descriptive statistics, χ2-tests, analysis of variance, t-test, Spearman correlation coefficient, and stepwise multiple regression.
Academic burnout was positively correlated to stress (r = .52, p < .001), anxiety (r = .50, p < .001) and depression (r = .44, p < .001). In those students with no clinical practice experience, anxiety and depression explained for academic burnout by 44%, and those students with clinical practice experience, stress and major satisfaction explained for 33% of academic burnout.
Universities and clinical institutions should establish a cooperative system to reduce stress, depression and anxiety and increase major satisfaction.
Capabilities in health monitoring enabled by capture and quantitative chemical analysis of sweat could complement, or potentially obviate the need for, approaches based on sporadic assessment of ...blood samples. Established sweat monitoring technologies use simple fabric swatches and are limited to basic analysis in controlled laboratory or hospital settings. We present a collection of materials and device designs for soft, flexible, and stretchable microfluidic systems, including embodiments that integrate wireless communication electronics, which can intimately and robustly bond to the surface of the skin without chemical and mechanical irritation. This integration defines access points for a small set of sweat glands such that perspiration spontaneously initiates routing of sweat through a microfluidic network and set of reservoirs. Embedded chemical analyses respond in colorimetric fashion to markers such as chloride and hydronium ions, glucose, and lactate. Wireless interfaces to digital image capture hardware serve as a means for quantitation. Human studies demonstrated the functionality of this microfluidic device during fitness cycling in a controlled environment and during long-distance bicycle racing in arid, outdoor conditions. The results include quantitative values for sweat rate, total sweat loss, pH, and concentration of chloride and lactate.
•The MnOx particles assembled with nanosheets were uniformly coated on PET fibers.•The growth process of MnOx layer on PET is clearly clarified.•MnOx/PET showed good activity for HCHO decomposition ...at room temperature.•MnOx/PET material is promising for indoor air purification due to its light, flexible and low air-resistant properties.
Removal of low-level formaldehyde (HCHO) is of great interest for indoor air quality improvement. Supported materials especially those with low air pressure drop are of necessity for air purification. Manganese oxides (MnOx) was in situ deposited on the surface of fibers of a non-woven fabric made of polyethylene terephthalate (PET). As-synthesized MnOx/PET were characterized by SEM, XRD, TEM, ATR-FTIR and XPS analysis. The growth of MnOx layer on PET is thought to start with partial hydrolysis of PET, followed by surface oxidation by KMnO4 and then surface-deposition of MnOx particles from the bulk phase. The MnOx particles assembled with nanosheets were uniformly coated on the PET fibers. MnOx/PET showed good activity for HCHO decomposition at room temperature which followed the Mars–van Krevelen mechanism. The removal of HCHO was kept over 94% after 10h continuous reaction under the conditions of inlet HCHO concentration ∼0.6mg/m3, space velocity ∼17,000h−1 and relative humidity∼50%. This research provides a facile method to deposit active MnOx onto polymers with low air resistance, and composite MnOx/PET material is promising for indoor air purification.
Low modulus, compliant systems of sensors, circuits and radios designed to intimately interface with the soft tissues of the human body are of growing interest, due to their emerging applications in ...continuous, clinical-quality health monitors and advanced, bioelectronic therapeutics. Although recent research establishes various materials and mechanics concepts for such technologies, all existing approaches involve simple, two-dimensional (2D) layouts in the constituent micro-components and interconnects. Here we introduce concepts in three-dimensional (3D) architectures that bypass important engineering constraints and performance limitations set by traditional, 2D designs. Specifically, open-mesh, 3D interconnect networks of helical microcoils formed by deterministic compressive buckling establish the basis for systems that can offer exceptional low modulus, elastic mechanics, in compact geometries, with active components and sophisticated levels of functionality. Coupled mechanical and electrical design approaches enable layout optimization, assembly processes and encapsulation schemes to yield 3D configurations that satisfy requirements in demanding, complex systems, such as wireless, skin-compatible electronic sensors.
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