• KSBB Journal
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• v.6 no.2
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• pp.181-187
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• 1991

Physiological and morphological characteristics of Anabaena azollae cells immobilized in a synthetic polymer, polyvinyl(PV), were investigated. The cell density of the non-immersed PV foam reached 4.4mg Chl/g dry wt. PV foam. This is 8 times higher than that of PV-immobiliz action in immersed batch system. And MSX-induced ammonia productivity and the photosynthectic oxygen evolution activity are higher than that of free cells after short-term dark storage. Nitrogenase activity and thermostability of photosynthetic activity are also higher than that of free Anabaena cells after immobilization. Total hydrogen production reached to 1.6ml $H_2$ per reactor (total 4mg Chl) after 6 days.

• Journal of Ocean Engineering and Technology
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• v.31 no.6
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• pp.413-418
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• 2017

In the present study, silica-aerogel-polyurethane foams were synthesized to improve the mechanical characteristics and insulation performance of the polyurethane foam applied to a liquefied natural gas carrier at a cryogenic temperature of $-163^{\circ}C$. A silica-aerogel-polyurethane foam bulk was prepared using a homogenizer by varying the weight ratio of the silica aerogel (0, 1, 3, and 5 wt%), while maintaining the contents of the polyol, isocyanate, and blowing agent constant. Compression tests were performed at room and cryogenic temperatures to compare the mechanical properties of the silica-aerogel polyurethane foams. The internal temperature of the universal testing machine was maintained through the cryogenic chamber. The thermal conductivity of the silica-aerogel-polyurethane foam was measured using a heat flow meter to confirm the insulation performance. In addition, the effect of the silica aerogels on the cells of the polyurethane foam was investigated using FE-SEM and FTIR. From the experimental results, the 1 wt% silica aerogel polyurethane foam showed outstanding mechanical and thermal performances.

• Smart Structures and Systems
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• v.13 no.4
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• pp.615-636
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• 2014

Aluminium Foam Sandwich (AFS) panels are becoming always more attractive in transportation applications thanks to the excellent combination of mechanical properties, high strength and stiffness, with functional ones, thermo-acoustic isolation and vibration damping. These properties strongly depend on the density of the foam, the morphology of the pores, the type (open or closed cells) and the size of the gas bubbles enclosed in the solid material. In this paper, the vibrational performances of two classes of sandwich panels with an Alulight(R) foam core are studied. Experimental tests, in terms of frequency response function and modal analysis, are performed in order to investigate the effect of different percentage of porosity in the foam, as well as the effect of the random distribution of the gas bubbles. Experimental results are used as a reference for developing numerical models using finite element approach. Firstly, a sensitivity analysis is performed in order to obtain a limit-but-bounded dynamic response, modelling the foam core as a homogeneous one. The experimental-numerical correlation is evaluated in terms of natural frequencies and mode shapes. Afterwards, an update of the previous numerical model is presented, in which the core is not longer modelled as homogeneous. Mass and stiffness are randomly distributed in the core volume, exploring the space of the eigenvectors.

• IMMUNE NETWORK
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• v.20 no.3
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• pp.22.1-22.21
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• 2020

In the progression of atherosclerosis, macrophages are the key immune cells for foam cell formation. During hyperlipidemic condition, phagocytic cells such as monocytes and macrophages uptake oxidized low-density lipoproteins (oxLDLs) accumulated in subintimal space, and lipid droplets are accumulated in their cytosols. In this review, we discussed the characteristics and phenotypic changes of macrophages in atherosclerosis and the effect of cytosolic lipid accumulation on macrophage phenotype. Due to macrophage plasticity, the inflammatory phenotypes triggered by oxLDL can be re-programmed by cytosolic lipid accumulation, showing downregulation of NF-κB activation followed by activation of anti-inflammatory genes, leading to tissue repair and homeostasis. We also discuss about various in vivo and in vitro models for atherosclerosis research and next generation sequencing technologies for foam cell gene expression profiling. Analysis of the phenotypic changes of macrophages during the progression of atherosclerosis with adequate approach may lead to exact understandings of the cellular mechanisms and hint therapeutic targets for the treatment of atherosclerosis.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.343-348
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• 1989

Production of shikonin derivatives by Lithospermum erythrorhizon cells by using polyurethane foam was invesliigated. Shikonin derivatives were effectively adsorbed mostly by phase distribution to polyurethane matrices and their production increased significantly compared to the suspension culture. The enhanced production of shikonin was probably due to more facilitated cell to cell con-tact and lowered intracellular shikonin concentration, both of which are known to be favorable for plant secondary metabolite production. In order to improve the process productivity, tell culture was conducted under various culture conditions: Of them, Schenk and Hildebrandt medium containing indole-3-acetic acid (1.75mg/ι) and kinetin (0.1mg/ι) was considered most appropriate for shikonin production. Production of shikonin increased about 4.5 times in the Schenk and Hildebrandt medium containing indole-3-acetic acid (1.15mg/ι) and kinetin (0.1mg/ι) when compared to the same medium containing p-chlorophenoxyacetic acid (2.0mg/ι) and kinetin (0.1mg/ι). When poly-urethane was used as the support material, a single-stage system was more preferred to the conventional two-stage culture system in terms of shikonin productivity.

• Design & Manufacturing
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• v.9 no.3
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• pp.24-28
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• 2015

Speaking in general terms the form injection process can be described as a new process-variant of already known structural foam molding technology which roots go back to the early sixties. The most limiting factors of already know foaming processes are large cell size and the lack of uniformity of these cells as well and the inability to foam all kinds of plastic materials. In this paper, Process Study on weight change in injection rate during foaming. Experimental conditions were set as the injection speed 50,150,300 and 450 mm/s. The experiments PA, PA+GF, PP, was confirmed that the weight increase to PP+TA.

• Steel and Composite Structures
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• v.51 no.1
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• pp.53-61
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• 2024

Aluminum foams sandwich panel (AFSP) has been used in engineering field, where cyclic loading is used in most of the applications. In this paper, the fatigue life of AFSP prepared by the bonding method was investigated through a three-point bending test. The mathematical statistics method was used to analyze the influence of different plate thicknesses and core densities on the bending fatigue life. The macroscopic fatigue failure modes and damage mechanisms were observed by scanning electron microscopy (SEM). The results indicate that panel thickness and core layer density have a significant influence on the bending fatigue life of AFSP and their dispersion. The damage mechanism of fatigue failure to cells in aluminum foam is that the initial fatigue crack begins the cell wall, the thinnest position of the cell wall or the intersection of the cell wall and the cell ridge, where stress concentrations are more likely to occur. The fatigue failure of aluminum foam core usually starts from the semi-closed unit of the lower layer, and the fatigue crack propagates layer by layer along the direction of the maximum shear stress. The results can provide a reference for the practical engineering design and application of AFSP.

• Journal of the Korean Geosynthetics Society
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• v.3 no.2
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• pp.3-11
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• 2004

Fabric Foam systems provide a variety of flexible bank protection for open channels and hydrulic structures. The structural performance and durability of conventional bank protection materials such as concrete, gravel, riprap and vegetation can be significantly improved by confining the materials within the cells of Fabric Foam system. This paper presents the results of field and laboratory tests carried out to evaluate the performance of new Fabric Foam System as a Bank Protection. The results of the tests confirmed effect of Fabric Foam System in Bank Protection.

• Korean Journal of Materials Research
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• v.23 no.7
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• pp.366-372
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• 2013

Flexible polyurethane/clay porous nanocomposite foams were synthesized using natural and organically modified montmorillonite clays such as bentonite, closite 10A and closite 30B. The content of nanoclays was varied from 1 to 5 wt% of polyol. Dispersion of clay in Polyurethane(PU) matrix was investigated by X-ray diffraction(Cu-$K{\alpha}$ rays of wavelength $1.54{\AA}$) using an X-ray diffractometer. Also, we determined that the thermal resistance of PU foam increased with added clay, compared to that of pure PU foam. The cell size and the fraction of open cells of the precursor foam were controlled by the addition of clay to the polyurethane foam. Modified clays were found to be more efficient cell openers than the unmodified clay. In addition, the tensile strength and elongation of the polyurethane/clay porous nanocomposites were examined. Increasing clay content increased the mechanical properties of the composites, such as tensile strength, and elongation at break. However, increasing the content over 5 wt% deteriorated the properties of the composites. We found that the nanofillers(bentonite, closite 10A and closite 30B) improved the thermal stability of the nanocomposite foam. The nanocomposite foam containing 3 wt% of closite 30B exhibited the best tensile strength and thermal stability.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.79-84
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• 2001

In this study, the effect of polyol structure(OH-value, functionality) on the reactivity, mechanical property and cell morphology of polyurethane foam and the possibility of replacing HFC-36smfc was examined by evaluating how each blowing agent(CFC-11, HCFC-l4lb, HFC-36smfc) affects the reactivity, mechanical property and cell morphology. Results of the experiment showed that as the functionality and OH-value of polyol increased, there was an increase in the temperature profile, reaction rate, density and compressive strength. However. as the functionality and OH-value increased. the ceil size became smaller The use of different kinds of blowing agents did not appear to have and significant influence on the temperature profile, reaction rate, density and compressive strength. The foam using HFC-365mfc produced more uniform cells compared to the foam using HCFC-l4lb.