• IMMUNE NETWORK
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• v.4 no.3
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• pp.131-142
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• 2004

In recent years, adjuvants have received much attention because of the development of purified subunit and synthetic vaccines which are poor immunogens and require adjuvants to evoke the immune response. Therefore, immunologic adjuvants have been developed and testing for most of this century. During the last years much progress has been made on development, isolation and chemical synthesis of alternative adjuvants such as derivatives of muramyl dipeptide, monophosphoryl lipid A, liposomes, QS-21, MF-59 and immunostimulating complexes (ISCOMS). Biodegradable polymer microspheres are being evaluated for targeting antigens on mucosal surfaces and for controlled release of vaccines with an aim to reduce the number of doses required for primary immunization. The most common adjuvants for human use today are aluminum hydroxide and aluminum phosphate. Calcium phosphate and oil emulsions have been also used in human vaccination. The biggest issue with the use of adjuvants for human vaccines is the toxicity and adverse side effects of most of the adjuvant formulations. Other problems with the development of adjuvants include restricted adjuvanticity of certain formulations to a few antigens, use of aluminum adjuvants as reference adjuvant preparations under suboptimal conditions, non-availability of reliable animal models, use of non-standard assays and biological differences between animal models and humans leading to the failure of promising formulations to show adjuvanticity in clinical trials. The availability of hundreds of different adjuvants has prompted a need for identifying rational standards for selection of adjuvant formulations based on safety and sound immunological principles for human vaccines. The aim of the present review is to put the recent findings into a broader perspective to facilitate the application of these adjuvants in general and experimental vaccinology.

• Journal of the Korean Ceramic Society
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• v.52 no.4
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• pp.253-263
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• 2015

Ordinary Portland cement is a widely favored construction material because of its good strength and durability and its reasonable price; however, spalling behaviour during fire exposure can be a serious risk that can lead to strength degradation or collapse of a building. Geopolymers, which can be synthesized by mixing aluminosilicate source materials such as metakaolin and fly ash, and alkali activators, are resistant to fire. Because the chemical composition of geopolymers controls the properties of the geopolyers, geopolymers with various Si:Al ratios were synthesized and evaluated as fire resistant construction materials. Rejected fly ash generated from a power plant was quantitatively analyzed and mixed with alkali activators to produce geopolymers having Si:Al ratios of 1.5, 2.0, and 3.5. Compressive strength of the geopolymers was measured at 28 days before and after heating at $900^{\circ}C$. Geopolymers having an Si:Al ratio of 1.5 presented the best fire resistance, with a 44% increase of strength from 29 MPa to 41 MPa after heating. This material also showed the least expansion-shrinkage characteristics. Geopolymer mortar developed no spalling and presented more than a 2 h fire resistance rating at $1,050^{\circ}C$ during the fire testing, with a cold side temperature of $74^{\circ}C$. Geopolymers have high potential as a fire resistant construction material in terms of their increased strength after exposure to fire.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.111-111
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• 2003

Several fungal isolates were isolated from diseased monochoria(Monochoria vaginalis, weed of paddy field), which has an resistance to sulfonyl urea(S.U.) herbicide, and were evaluated in the laboratory and greenhouse as potential mycoherbicide. Eight fungi, Alternaria sp., Colletotrichum sp., Curvularia sp., Paenicillium sp and etc. were observed in the isolates. Pathogenicity testing were done on the monochorias in the greenhouse. Monochorias were inoculated with suspensions containing conidia of each isolate at the rates of 1.0 ${\times}$ 10$\^$5/ conidia/ml and 0.1％ Tween 80 with hand-gun sprayer. Curvularia sp. and an unidentified fungal isolate caused 90-95％ mortality on the monochorias 15∼20 days after inoculation. However the other isolates induced slight symptom of disease on the monochorias. In the early stage of disease development sun-burn appearance was shown at the infected site and the last infected leaves and stems were withered to death. Subsequently the pathogenicity on the rice was evaluated with above two effective isolates. From the test an unidentified isolate showed pathogenicity on the rice but Curvularia sp., named as DBB2003, didn't. Now the mass production and formulation using Curvularia sp. DBB2003 are in progress and the field test will be followed. Combination product with Curvularia sp. DBB2003 and chemical herbicide will be more effect to control the monochoria resisted on S.U. herbicide and need to be further tested.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.3
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• pp.75-86
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• 1991

Ion exchange strengthening is a chemical process whereby large alkali ions(such as potassium) are substituted for smaller ions(sodium) within the surfaces of glasses and ceramics, thereby reducing the thermal expansion coefficient of this surface region, and creating beneficial state of compressive stress within the near surface region. The purpose of this study was to determine the effects of ion exchange and etching treatments on the strength of some dental porcelains. Two feldspathic dental porcelains(Vitadur-N, G-Cera) were used in this study. A commercial ion exchange paste and etching gel containing 8% hydrofluoric acid were used for surface conditioning. Transverse strength was measured using a universal testing machine and the technique of EPMA(electron probe micro analysis) was used to access the potassium contents. The results were as follows: 1. Improvement in strength was only obtained by treating the surface placed in tension. 2. No changes in the dimensions of the treated specimens were detected when samples were measured with a micrometer. 3. There was significant increase in transverse strength of G-Cera IV group treated with etching and ion exchange, compared with G-Cera II group only treated with ion exchange. 4. From the results of EPMA test, increase in potassium contents was observed on the surface treated with ion exchange paste.

• Journal of Technologic Dentistry
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• v.31 no.1
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• pp.63-74
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• 2009

Partial or complete prosthesis is needed when teeth are lost due to various kinds of reason. Artificial teeth recover occlusion instead of natural teeth. Artificial teeth are required of esthetics, fragile resistance and abrasive resistance. Artificial tooth is made of acrylic resin or porcelain. Nowadays, acrylic resin artificial teeth are mainly used. Acrylic resin teeth are occluded with natural teeth, gold alloy, Ni-Cr alloy or porcelain etc. Acrylic resin teeth have similar translucency, gloss of natural teeth. And it has good chemical bond with denture base material, but it has low wear resistance. The aim of this study is to compare wear resistance among several denture teeth(Endura, SR-orthosit-PE, Planustar) and between artificial resin denture teeth and opposing 3 restorative materials(gold, Ni-Cr alloy, porcelain). Wear tests were conducted with a rotating wear testing apparatus(pin-on-disk type wear tester) under conditions of rpm 180, 75 minutes and constant loading of 50N. The upper part was the cusp of maxillary first molar and the lower part was a disk type restorative materials. To make similar oral environment, water was supplied continually. The acrylic resin teeth wear was determined by weighing the cusp each 5 minutes during 75 minutes test. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces. The results were as follows: 1. Wear rates of acrylic resin teeth opposing to the restorative materials were high in order of Porcelain, Gold, Ni-Cr alloy (p<.05). 2. Wear resistance rate opposing to the Porcelain disk, was shown in order of Endura, SR-orthosit-PE, Planustar. The wear rate of opposing to porcelain disk was above two times more than that of other groups (p<.05). 3. Wear resistance rates opposing to the Gold, Ni-Cr alloy disk, was shown in order of Endura, SR-orthosit-PE, Planustar (p<.05). 4. A degree of the surface hardness is directly proportional to the degree of wear resistance. There are statistically significant differences between each groups (p<.05).

• Journal of Hydrogen and New Energy
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• v.31 no.3
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• pp.284-292
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• 2020

In this study, hydrogen charging was conducted for API X70 steel by the electro-chemical hydrogen charging method. Right after hydrogen was diffused from the specimen surface to the inside of the X70, the small punch tests and hydrogen concentration analysis was conducted within 5 minutes. Hydrogen was analyzed by melting the whole specimen and detect the gas after melting. Mechanical properties were measured by the small punch (SP) testing. Fracture surface and specimen surface were observed using scanning electron microscope. Three tests were repeated for study sensitivity of the SP test results under a same charging condition. It was observed that the variation of the maximum load, SP displacement at failure, hydrogen concentration as the charging period was not much in the case of X70 as the other steel such as Inconel. It can be argued that X70 base metal may have high hydrogen damage resistance and hydrogen diffusion in the base metal would not cause much embrittlement. Limitations of the SP test with 0.5 mm thickness for hydrogen damage test for X70 were discussed.

• Analytical Science and Technology
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• v.9 no.1
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• pp.26-34
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• 1996

A method to determine the trace amount of Se and Bi in the scalp hair using the hydride generation inductively coupled plasma atomic emmission spectrometry was studied. The optimum operation conditions of ICP for hydride generation are 0.6~0.8L/min for the carrier gas flow rate, and 6mm above the induction coil for the observation height. Hydrochloric acid concentrations for the optimum hydride generation conditions were greater than 1.5M when 2.5% $NaBH_4$ and NaOH were used, and greater than 0.5M when 2.5% $NaBH_4$ and 0.1% NaOH were used. Severe interference effects are observed from transition metals such as Cu and Ni, and they could be circumvented by the coprecipitation with lanthanum hydroxide.

• Journal of Embryo Transfer
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• v.23 no.4
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• pp.229-237
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• 2008

Recently, parabens have been believed to act as xenoestrogens, an identified class of endocrine disruptors (EDs). These environmental compounds are the most well-known as preservatives in many commercial products, including food, cosmetics and pharmaceutical industries. It has been demonstrated that the human health risks of parabens result from a long-term exposure to skin in which this chemical group is rapidly absorbed through the skin. On the other hand, parabens are also completely absorbed from gastrointestinal tract. It has reported that these substances possess several biological effects in which inhibitory property involved in membrane transports and mitochondrial functions is considered to be important for their action. Testing of parabens has revealed that estrogen-like activities of these chemicals are much less potent than natural estrogen, $17{\beta}$ estradiol (E2). Additionally, the estrogenicity of individual paraben- compounds is distinct depending upon their biochemical structure. Recent findings of paraben-estrogenic activities have shown that these compounds may affect breast cancer incidence in women, suggesting adverse ecological outcomes of this environmental group on human and animal health. Although the biological and toxicological effects of parabens have been demonstrated in many previous studies, possible mechanism(s) of their action are required to be explored in order to bring the better understanding in the detrimental impacts of parabens in human and wildlife. There have several different types of parabens which are the most widely used as preservatives. These include methyl-paraben, ethylparaben, propylparaben, butylparaben and p-hydroxybenzoic acid, a major metabolite of parabens. In this review, we summarize current database based on in vitro and in vivo assays for estrogenic activities and health risk assessment of paraben- EDs which have been published previously.

• Biomedical Science Letters
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• v.10 no.2
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• pp.85-92
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• 2004

Immortalization of primary corneal cells has influence on pharmacy, medical and biological fields. Especially, investigation of immortalization mechanism using viral oncoproteins is useful for medical treatments, and these cell lines will be useful materials for toxic test of medical supplies and cell biological experiments. Rabbit corneal fibroblasts in culture undergo a finite number of divisions before they reach a terminally non-proliferating state known as replicative senescence. Therefore, we attempted to induce immortalization of rabbit corneal fibroblasts with SV 40 large T antigen. As a result of experiment, expression of SV 40 large T antigen was confirmed, and expression of proteins related to cell cycle repressor was decreased in the transfection group compared with non-transfection group. According to the results of cell cycle phase distribution test, SV 40 large T antigen-transfected cells had obtained higher proliferation rate than primary cells. It was confirmed that during induction of immortalization, SV 40 large T antigen was not able to increase telomerase activity. In conclusion, we made a rabbit corneal fibroblast cell line with SV40 large T antigen. This cell line will be useful for further studies of mammalian fibroblast biology, particularly with regard to angiogenesis and malignant transformation. In addition, this cell line offers opportunity for testing potential therapeutics and can be used for toxicity tests of materials or cosmetics. In the future, our cell line can potentially be utilized in a wide range of biology related fields.

• Tunnel and Underground Space
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• v.26 no.2
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• pp.68-86
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• 2016

Understanding the frictional properties of rock discontinuities is crucial to ensure the stability of underground structures. In particular, the frictional behavior at depth depends on the complex interaction among mechanical, hydraulic, thermal and chemical characteristics and their coupled effects. In this study, a series of shear tests were carried out in a triaxial compression chamber to investigate the shearing behavior of saw-cut granite surface and rough shear surface of synthetic rocks. The test results were analyzed using Coulomb's shear strength criterion. The frictional behavior of saw-cut granite surface showed little variation at different confining, water pressures and temperature conditions, however in case of synthetic rocks, the frictional behavior showed different trend depending on normal stress level. In addition, the variation of stiffness and dilation at different testing conditions were analyzed, and the stiffness and dilation showed little variation at different water pressures and temperature conditions.