• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.513-528
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• 2020

This paper presents the results of an experimental study on the residual behavior of reinforced recycled aggregate concrete (RRAC) beam-columns after exposure to elevated temperatures. Two parameters were considered in this test: (a) recycled coarse aggregate (RCA) replacement percentages (i.e. 0, 30, 50, 70 and 100%); (b) high temperatures (i.e. 20, 200, 400, 600, and 800℃). A total of 25 RRAC short columns and 32 RRAC beams were conducted and subjected to different high temperatures for 1 h. After cooling down to ambient temperature, the following basic physical and mechanical properties were then tested and discussed: (a) surface change and mass loss ratio; (b) strength of recycled aggregate concrete (RAC) and steel subjected to elevated temperatures; (c) bearing capacity of beam-columns; (d) load-deformation curve. According to the test results, the law of performance degradation of RRAC beam-columns after exposure to high temperatures is analyzed. Finally, introducing the influence coefficient of RCA replacement percentage and high temperatures, respectively, to correct the calculation formulas of bearing capacity of beam-columns in Chinese Standard, and then the residual bearing capacity of RRAC beam-columns subjected elevated temperatures is calculated according to the modified formulas, the calculated results are in good agreement with the experimental results.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.3
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• pp.207-218
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• 2022

Aging in mammals, including humans, is accompanied by loss of bone and muscular function and mass, characterized by osteoporosis and sarcopenia. Although resistance exercise training (RET) is considered an effective intervention, its effect is blunted in some elderly individuals. Fibroblast growth factor (FGF) and its receptor, FGFR, can modulate bone and muscle quality during aging and physical performance. To elucidate this possibility, the FGFR inhibitor NVP-BGJ398 was administrated to C57BL/6n mice for 8 weeks with or without RET. Treatment with NVPBGJ398 decreased grip strength, muscular endurance, running capacity and bone quality in the mice. FGFR inhibition elevated bone resorption and relevant gene expression, indicating altered bone formation and resorption. RET attenuated tibial bone resorption, accompanied by changes in the expression of relevant genes. However, RET did not overcome the detrimental effect of NVP-BGJ398 on muscular function. Taken together, these findings provide evidence that FGFR signaling may have a potential role in the maintenance of physical performance and quality of bone and muscles.

• Steel and Composite Structures
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• v.45 no.3
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• pp.369-388
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• 2022

Composite effect between steel and recycled aggregate concrete (RAC) in steel reinforced-RAC (SRRAC) structures can effectively improve RAC's adverse mechanical properties due to the natural defects of recycled coarse aggregate (RCA). However, the performance of SRRAC after thermal exposure will have a great impact on the safety of the structure. In this paper, firstly, the mechanical properties of SRRAC structures after high temperatures exposure were tested, including 24 SRRAC columns and 32 SRRAC beams. Then, the change rules of beams and columns performance with the maximum temperature and replacement percentage were compared. Finally, the formulas to evaluate the residual bearing capacity of SRRAC beams and columns after exposure to high temperatures were established. The experimental results show that the maximum exposure temperature can be judged by the apparent phenomenon and mass loss ratio of RAC. After high temperatures exposure, the mechanical properties of SRRAC beams and columns change significantly, where the degradation of bearing capacity and stiffness is the most obvious. Moreover, it is found that the degradation degree of compression member is more serious than that of flexural member. The formulas of residual bearing capacity established by introducing influence coefficient of material strength agree well with the experimental results.

• Food Science and Biotechnology
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• v.15 no.3
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• pp.447-452
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• 2006

To determine the functions of specific cell wall polysaccharides, polysaccharides of three mutants, mur3-1, mur3-2, and mur3-3, obtained from Arabidopsis wild type, underwent structural characterization. Upon sequential separation of pectins (RG-I and RG-II) and cross-linking glycans (xyloglucan, XG), only XG was affected by the mud mutation. Wild-type XG contained a considerable amount of fucose, whereas the fucose level in mur3 XGs was less than 20% that of wild type. Further analysis of XGs by matrix-assisted laser-induced/ionization time-of-flight (MALDI-TOF) mass spectrometry indicated that mud lines considerably or completely lost the fucosylated XG oligosaccharides such as XXFG and XLFG and the double-galactosylated oligosaccharide XLLG $^1H$-NMR spectroscopic analyses of the XG oligosaccharides from mur3-3 plant revealed the absence of fucose and a galactose level in the galactosylated side chain that was reduced by 40% compared to that of Arabidopsis wild-type plant. In contrast, 85% less fucose and a slight loss of galactose were observed in the mur3-1 and mur3-2 lines which show normal growth habit. Of the three Arabidopsis mur3 lines studied here, mur3-3 is disrupted by a T-DNA insertion in the exon of MUR3 which encodes XG-specific galactosyltransferase, and exhibits slight dwarfism. These results indicated that the T-DNA insertion at the MUR3 locus did not induce the complete loss of galactose in XG, and that galactose, rather than fucose, in the XG side chains made a major contribution to overall wall strength.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.200-209
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• 2019

To improve the water resistance of melamine-urea-formaldehyde (MUF) resins, different levels of blocked polymeric 4,4 diphenyl methane diisocyanate (B-pMDI) were blended with MUF resins to prepare B-pMDI/MUF hybrid adhesives, and their adhesion performances were evaluated for the surface lamination of fancy veneer on plywood. FT-IR spectra showed that the de-blocked -NCO groups reacted with the -OH of hydroxymethyl groups of the MUF resins to form urethane bonds at 2% B-pMDI/MUF, which was detected before and after their hydrolysis. The mass loss after the hydrolysis consistently decreased as the B-pMDI level increased, indicating an improvement in the water resistance. As the B-pMDI level increased, the activation energy of hybrid adhesives decreased, which improved the reactivity of the hybrid adhesives. Additionally, the water resistance improvement of the hybrid adhesives increased the tensile shear strength of the surface laminated plywood in semi-water proof and water-proof by 23 % and 8 %, respectively, at 2% B-pMDI level. This was likely due to the urethane linkages in the hybrid adhesives. However, the formaldehyde emission from plywood panels bonded with the hybrid adhesives increased in the dry state, indicating incomplete curing of the hybrid adhesives.

• Journal of the Korean Society for Railway
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• v.17 no.1
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• pp.7-13
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• 2014

Stiffness variations and wave propagation/reflection in railway catenaries are the primary sources of contact loss between a pantograph and a railway contact wire. This paper analyzes which design parameter is more important for 200km/h conventional rail and 300km/h high-speed rail, in order to effectively reduce the contact loss. For the high-speed rail, the wave propagation and reflection in the overhead contact lines are more influential than the stiffness variation over a span. When the high-speed rail needs to speed-up, it is necessary to develop higher strength contact wires in order to increase the wave propagation speed. In addition, the dropper clamp mass should be reduced in order to alleviate the wave reflection. However, it is noted that the increase in the tension to a messenger wire could deteriorate the current collection quality, which contrasts with expectations. For the 200km/h conventional rail, the stiffness variation over a span is more influential than the wave propagation and reflection. Therefore, shortening span length, increasing the tension in the contact wire and optimizing the location of the droppers are recommended for a smoother stiffness variation over the span.

• Composites Research
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• v.30 no.1
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• pp.21-25
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• 2017

The aim of this study is to fabricate composite bone plates consisted of unidirectional biodegradable glass fibers (BGF) and polylactic acid (PLA) and evaluate the performance of the composite bone plates according to the temperature ($50.0^{\circ}C$) of PBS (Phosphate Buffer Saline) solution and exposure time (0~3 weeks). Mechanical characteristics, such as bending stiffness, flexural strength, water uptake and mass loss, were investigated and the results showed that mechanical properties of the plates decreased as soaking duration increased due to loss of composite material.

• Journal of Ginseng Research
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• v.45 no.6
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• pp.744-753
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• 2021

Background: Gintonin-enriched fraction (GEF) is a new non-saponin component glycolipoprotein isolated from ginseng root. This study examined the effect of GEF on age-related sarcopenia in old C57BL/6J mice. Methods: Young (3-6 months) and old (20-24 months) C57BL/6J mice received oral GEF (50 mg/kg/day or 150 mg/kg/day) daily for 5 weeks. During the oral administration period, body weight and grip strength were measured weekly. After sacrifice, muscles from the hindlimb were excised and used for hematoxylin and eosin staining and western blotting to determine the effects of GEF on sarcopenia. The thymus was photographed to compare size, and flow cytometry was performed to examine the effect of GEF on immune homeostasis in the thymus and spleen. Blood samples were collected, and the concentrations of pro-inflammatory cytokines and IGF-1 were measured. Results: GEF caused a significant increase in muscle strength, mass, and fiber size in old mice. GEF restored age-related disruption of immune homeostasis by maintaining T cell compartments and regulating inflammatory biomarkers. Thus, GEF reduced common low-grade chronic inflammatory parameters, which are the main cause of muscle loss. Conclusion: GEF maintained immune homeostasis and inhibited markers of chronic inflammation, resulting in anti-sarcopenia effects in aged C57BL/6J mice. Thus, GEF is a potential therapeutic agent that slows sarcopenia in the elderly.

• Advances in environmental research
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• v.3 no.4
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• pp.337-353
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• 2014

The determination of the effectiveness of the immobilization of blasting dust (waste generated in galvanic activities) in cement matrix, as well of mechanical, physical and microstructural properties of concrete paving blocks produced with partial replacement of cement was the objective of this work. The results showed that blasting dust has high percentage of silica in the composition and very fine particle size, characteristics that qualify it for replacement of cement in manufacturing concrete blocks. The replacement of Portland cement by up to 5% residues did not cause a significant loss in compressive strength nor increase in water absorption of the blocks. Chemical tests indicated that there is no problem of leaching or solubilization of contaminants to the environment during the useful life of the concrete blocks, since the solidification/stabilization process led to the immobilization of waste in the cement mass. Therefore, the use of blasting dust in the manufacture of concrete paving blocks is promising, thus being not only an alternative for proper disposal of such waste as well as a possibility of saving raw materials used in the construction industry.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.251-258
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• 1990

Optimal design of heat exchanger for closed CO$_{2}$ gas turbine plant of three processes selected from the result of cycle analysis have been discussed previously paper(I) has been carried out under specified inlet and outlet conditions. Independent variables such as number of parallel connection, tube diameter, shell side and tube side pressure loss as well as dependent variables such as shell diameter, number of tubes, number of serial connections were all characterized according to the standardization or so. Search method was used to construct a computer simulation together with the calculation of heat transfer rate by logarithmic mean temperature difference method. Strength analysis of major parts was carried to examine their dimensions satisfying heat transfer and pressure loss requirements.