• Parasites, Hosts and Diseases
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• v.25 no.2
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• pp.99-109
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• 1987

The present study was carried out to examine the effect of a calcinogen, aflatoxin B1 on the ultrastructural changes of ciliary epithelial cells in mice infected with Clonerchis sinensis. A total of 93 male albino mice(BALB/c strain) was divided into 3 groups; group I, treated with 1.0 ppm aflatoxin Bl for 12 weeks; group II, given 50 C. sinensis n;etacercariae, and group III, given 50 metacercariae and treated with 1.0 ppm aflatoxin Bl for 12 weeks. Three mice served for untreated-uninfected controls. From 4 weeks after the treatsment and/or in(ection, three mice from each group were sacrificed at 4 week intervals up to the 40th week, and their hepatobiliary tissues were prepared for transmission electron microscopy. The most prominent ultrastructural changes in group I were remarkable enlargement of nuclear size, separation of nucleolus, dispersed chromatin granules in nuclei and increased dense granules along the inner membrane of nuclei. In the cytoplasm there was slight proliferation of mitochondria and endoplasmic reticulum (ER) at earlier stage. At the 12th week separation of fibrillar and granular components of the nucleolus was a characteristic finding. As the time elapsed, epithelial cells showed fiattened-cuboidal form and a tendency of atrophy. Most of the nuclei were elongated and polygonal in shape. In group II the appearance of elaborate interwoven folds of lateral cytoplasm forming a labyrinth of interconnected intercellular space and variety in nuclear shape were the prominent fadings at earlier stage. The cytoplasm showed slight proliferation and dilatation of mitochondria and ER, and a small number of mucin droplets. In the basement membrane scanty fibrous cells were seen. With time, variety in nuclear shape, marked proliferation and dilatation of rough ER and some collagen fibrils were demonstrated. Other features of intracellular organelles and mucin droplets persisted. In group III cuboidal epithelial cells showed their remarkably enlarged and irregular nuclei, increased chromatin granules in the nuclei, separated nucleoli, proliferated and dilated rough ER. With time, sequestered mitochondria showed blob-like evaginations which lacked cristae and dense matrix, and were limited by a single membrane. Since the 20th week, microvilli were relatively scanty and poorly developed. Organelles and inclusions in the cytoplasm of metaplastic cells were poor. Nuclei were variable in shape. The nlost prominent changes at later stage were separation of nuclei from the cytoplasm, and appearance of numerous and irregularly angled electron dense granules in the nuclei.

• Parasites, Hosts and Diseases
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• v.31 no.4
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• pp.301-314
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• 1993

An electron microscopic study was performed to observe the ultrastructure of the tegument of U seoulensis. The outer surface of the tegument was covered with a tnlaminated plasma membrane. The electron-dense cytoplasmic layer was $2.5{\;}\mu\textrm{m}$ wide In the anterior portion and contained numerous vacuoles, mitochondriae and granular materials in its matrix. The basement layer was 330 nm wade or so, and Its numerous extensions protruded into the cytoplasmic layer. The sensory organ was composed of a small vesicle of $1.7{\;}{\times}{\;}1.1{\;}\mu\textrm{m}$ in dimensions, which possessed a cilium of $1.2{\;}{\times}{\;}0.19{\;}\mu\textrm{m}$ in size. The pharynx was composed of the epithelial layer of about $0.5{\;}\mu\textrm{m}$ wide, well developed muscle layer and basement layer. The tegument of the oral sucker was composed of a cytoplasmic layer of $0.4-0.5{\;}\mu\textrm{m}$ width, a narrow basement layer, a well developed muscle layer and tegumental cells. Some kinds of secretory granules that seemed to be originated from the cells of the oral sucker were observed In the parenchymal portions of the adjacent cells. The tribocytic organ consisted of numerous microvilli. The microvilli were 5 nm wide and heptalaminated. Two types of secretory granules originated from the gland cells of tribocytic organ were observed In the tegument and parenchyme. The tegumental cells were irregular in shape, and of which nuclei were multifarious.

• Korean Journal of Food Science and Technology
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• v.10 no.3
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• pp.306-312
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• 1978

Residue levels of an organochlorine insecticide, BHC, were determined for brown rice samples produced in Korea by collection and field experiments to obtain the following results. 1) Residue levels of total BHC in 112 samples (an Indica type variety Tongil) produced in 1976 and collected from 9 provinces in proportion to the production level of rice ranged from 0.0010 to 0.0762 ppm, the average being 0.0061 ppm. 2) The residue levels in samples from Jeonbook, Kyongnam and Choongnam provinces were higher than the average for whole samples. BHC isomers were found in the order of ${\alpha}>{\gamma}>{\beta}>{\delta}$ isomers, and the detection frequency by range were 89.3% below 0.01 ppm, 9.8% for $0.01{\sim}0.05{\;}ppm$ and 0.9% for $0.05{\sim}0.10{\;}ppm$. 3) In field experiments according to conventional agronomical practices, the brown rice samples after spraying of BHC at the first generation time of rice stem borer (4 kg of 6% granular formulation/10 a paddy field) showed a little higher residue level than control samples, but not more than 0.035 ppm, whereas samples after spraying at the second generation time (3 kg/10 a) contained in the range of $0.04{\sim}0.19\;ppm$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.1-7
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• 2020

As of 2018, Steel slag was generated approximately 24.23 million tons. Howeve, except blast furnace slag, steel slag is a typical by-product which does not have a clearly defined purpose in recycling. Thus, countries around the world are putting great efforts into developing a purpose for the recycling of steel slag. The vast habitat foundation of marine life has been destroyed due to recent reckless marine development and environment pollution, resulting in intensification of the decline of marine resources, and a solution to this issue is imperative. In order to propose a method to recycle large amounts of by-product slag into a material that can serve as an alternative to natural aggregate, the engineering properties and applicability for each mixing factor of environment friendly porous concrete as a material for the composition of seawater purification were in this study. Regarding the nutrient elution properties, it was clear that the nutrients continuously flowed out up to an immersion time by 8 months in natural seawater; the nitrogenous fertilizer displayed excellent elution properties in this regard.

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.235-244
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• 2010

Ultrastructural characteristics of the testis and spermatogenesis of Crassostrea gigas were investigated by Transmission and Scanning Electron microscope observations. The testis is a diffuse organ consisting of branching acini containing differentiating germ cells in a variety of stages. The acinus is surrounded by an intermitent layer of myoepithelial cells andis divided into subcompartments that are partially separated by pleomorphic accessory cells which remain in close contact with germ cells until late stages of development. these accessory cells contain a large quantity of glycogen particles and lipid droplets in the cytoplasm. Therefore, it is assumed that they are involved in the supplying of the nutrients for germ cell development, while any phenomena associated with phagocytosis of undischarged, residual sperms by lysosomes could be find in the cytoplasm of the accessory cells. The morphology of the spermatozoon has a primitive type and is similar to those of other bivalves. Mature spermatozoa consist of broad, cap-shaped acrosomal vesicle, subacrosomal material (containing axial rod embedded in a granular matrix), a oval nucleus showing deeply invaginated anteriorly, two triplet substructure centrioles surrounded by four spherical mitochondria, and satelite fibres appear to the distal centriole and plasma membrane. Spermatozoa of C. gigas resemble to those of other investigated ostreids. In particular, the anterior region of the acrosomal vesicle is transversely banded. It is assumed that differences in this acrosomal substructure are associated with the inability of fertilization between the genus Crassostrea and other genus species in Ostreidae. Therefore, we can use sperm morphology in the resolution of taxonomic relationships within the Ostreidea. The spermatozoon is approximately $42-47{\mu}m$ in length including an oval sperm nucleus (about $0.91{\mu}m$ in length), an acrosome (about $0.42{\mu}m$ in length) and tail flagellum ($40-45{\mu}m$). The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9 + 2 structure. These morphological charateristics of acrosomal vesicle belong to the family Ostreidae in the subclass Pteriomorphia.

• Asian Journal of Turfgrass Science
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• v.20 no.2
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• pp.175-190
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• 2006

The term mycoherbicide started in 1970, but its interest heightened due to increase costs of chemical herbicides. A classical biocontrol agent is expected to become a permanent part of its new environment and do no harm to it. Contemporary biological control agent(BCA) must be produced by artificial culture and could be applied like chemical herbicides over weeds. BCA is different from the classical approach in that it released through natural spread. To date 26 species of fungi are used as classical BCA against 26 species of weeds in seven countries. There are a number of examples of pathogens attacking non-target plants. But through risk assessments which include understanding the taxonomy, biology and ecology, the target and non-target species, it will be safe to introduce of exotic pathogens to control weeds. But pathogens have not been successfully used in practice. Many mycoherbicides show potential in laboratories, but are ineffective in the field and not consistent from year to year or field to field. There is also a lack of understanding humidity, dew formation and temperature and their effects on suppression of weeds by plant pathogens. Potential pathogen must be selected as a BCA. Previous studies suggest that these pathogens must (1) produce abundant and durable inoculum in artifical culture, (2) be genetically stable and weed specific and (3) kill weeds in control. A granular preparation of mycoherbicide into sodium alginate is lighter than liquids and less bulky than organic matter. Gel forms have also been used.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.46 no.1
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• pp.73-80
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• 2020

Psychological stress can affect the physiological condition of the skin and cause various cutaneous disorders. The stress hormone cortisol is secreted by various skin cells such as fibroblasts, keratinocytes, and melanocytes. Tight junctions (TJs) are cell-cell junctions that form a barrier in the stratum granulosum of mammalian skin. TJs can also affect other skin barriers and are affected by chemical, microbial, or immunological barriers. Stress can cause damage to the skin barrier. Interestingly, to our knowledge, there has not been any research demonstrating the involvement of TJs in this process. In this study, cortisol was used to treat keratinocytes to determine its role in regulating TJs. We found that cortisol damaged skin barrier function by regulating the gene expression and structure of TJ components. Cortisol also inhibited the development of the granular layer in a skin equivalent model. These results suggest that cortisol affects the skin barrier function by the regulation of TJs.

• The Journal of the Petrological Society of Korea
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• v.15 no.3 s.45
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• pp.128-138
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• 2006

The west stone pagoda of Gameunssji temple site (National Treasure No. 112) has been damaged mainly by fracture, exfoliation and granular disintegration. In this study, the source area of the rocks using the west stone pagoda was examined in terms of petrological feature, magnetic susceptibility, and ${\gamma}-ray$ spectrometer. The stones include abundant crystal fragments of biotite, quartz and feldspars in the fine-grained matrix; they are petrographically discriminated to vitric-crystal tuff or crystal tuff. Measured magnetic susceptibility values are of from 10 to 20 $({\times}10^{-3}\;SI\;unit)$. From the ${\gamma}-ray$ spectrometer measurement K, eU, and eTh contents of the stones are about 3%, 0 to 8ppm, and 9 to 18 ppm, respectively. These features are used as indicators to presume the source area of the stones. Comparing the petrographical and chemical characteristics between the stones of the west stone pagoda and the country rocks near the Gameunsaji temple site, it is suggested that the most similar country rock to the stones could be dacitic volcanic rocks of the Beomgokri group in the Waeup basin. The Beomgokri group is lithostratigraphically divided into Waeupri tuff, Yongdongri tuff and Beomgokri volcanic rocks. Among the three rocks, the crystal tuff of the Beomgokri volcanic rocks seems likely to have been the source rock of the stones of the west stone pagoda.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.1-6
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• 2005

Analogue physical modelling using granular materials (i.e., sandbox experiments) has been applied with great success to a number of geological problems at various scales. Such physical experiments can also be simulated numerically with the Discrete Element Method (DEM). In this study, we apply the DEM simulation to the collision between the Indian subcontinent and the Eurasian Plate, one of the most significant current tectonic processes in the Earth. DEM simulation has been applied to various kinds of dynamic modelling, not only in structural geology but also in soil mechanics, rock mechanics, and the like. As the target of the investigation is assumed to be an assembly of many tiny particles, DEM simulation makes it possible to treat an object with large and discontinuous deformations. However, in DEM simulations, we often encounter difficulties when we examine the validity of the input parameters, since little is known about the relationship between the input parameters for each particle and the properties of the whole assembly. Therefore, in our previous studies (Yamada et al.,2002a,2002b,2002c), we were obliged to tune the input parameters by trial and error. To overcome these difficulties, we introduce a numerical biaxial test with the DEM simulation. Using the results of this numerical test, we examine the validity of the input parameters used in the collision model. The resulting collision model is quite similar to the real deformation observed in eastern Asia, and compares well with GPS data and in-situ stress data in eastern Asia.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.343-355
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• 2021

Agricultural reservoirs seek human convenience by supplying agricultural water and providing flood damage effects and rest areas at the same time, but preventing them from aging reservoirs and earthquakes is important. The safety of levees is influenced by field material properties such as soil parameter values of the granular materials that make up the levees, but since precision safety diagnosis or general literature values are diverted, the final safety factors are limited to material properties alone. Since safety factors are determined by physical characteristic values and embankment shapes and have a significant impact on safety factors, accurate contemplation is required when examining reinforced cross sections. Therefore, this study analyzed the case of reasonable and economical reinforcement intersections when designing '◯◯reservoir' in Goheung-geun, Jeollanam-do using the GEP-SLOPE program to enable rational economic design of reinforcement intersections through repeated reviews. As a result of reducing and analyzing the first, second, and third seismic reinforcement of the levees, it was confirmed that the safety ratio was secured even with a significantly smaller amount of reinforcement than the first, second, and lower slopes by obtaining design standards of 1.20. In addition, when determining all seismic reinforcement cross-sectional shapes, it was confirmed that the shape that reinforces only the lower side rather than the upper side of the slope and the entire slope was economical with minimized cross-sectional reinforcement.