• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.297-297
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• 2006

Recently columnar liquid crystals have been studied due to their possible application to organic conducting materials. Supramolecular columnar liquid crystals consist of mesogenic unit which can aggregate into discs that will make up the columns which associate to form a two-dimensional network. In this study, we prepared supramolecular columnar liquid crystals containing hydrogen bonding between carboxylic acid and, pyridine moieties. Thermal and structural properties of prepared complexe were investigated, and it exhibited hexagonal columnar structure ($Col_{h}$) at room temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.6
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• pp.357-366
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• 2003

This study was conducted to develop n convenient and efficient granular type absorbent with high CEC from powdery zeolite, which is a waste produced while crushing the natural zeolite of Korea to get a particular particle size. The change of mineralogical characteristics during hydrothermal alternation of natural zeolite to Na-P zeolite in alkaline solution at various reaction times was determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and total elemental analysis. The columnar aggregate of Na-P Zeolite was produced by calcinating the natural zeolite-charcoal extrudates of about 3 mm diameter. In 24 hours reaction, clinoptillonite, mordenite and feldspar in natural zeolite were disappeared by 3 N NaOH treatment, while Na-P Zeolite with spherical granular structure was newly detected by XRD. As increasing reaction time, Si/Al ratio in remaining solution was deceased. The CEC of the synthesized material increased more than 2 times compared with that of natural zeolite, although the diameter of Na-P zeolite were rather increased.

• The Korean Journal of Zoology
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• v.32 no.3
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• pp.211-220
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• 1989

The fine structure of the aggregate glands-one of the capture thread producing organs-in the orb web spider, Nephila clavata L.Koch, is studied with light and electron microscopes. Gluey capture threads or sticky spirals of the orb web are originated from the silks of two flagelliform glands and four aggregate glands which are connected to the posterior spinnerets, and the arrangement fo their spigots(large spinning tubes) shows a charaterstic form called "triad". The aggregate galnd is composed of large and multilobed secretory portion and thick excretory duct surrounded by large irregular nodules. The excretory duct of the aggregate galnds basically consists of three superposed types of cells which are inner columnar epithelium, nodule-forming cells and outer connestives. The cuticles of the proximal duct near the secretory portion are composed of endocuticle and exocuticle, whereas ghe distal duct near the spinning tubes has a electron lucent subcuticle which had the functions of water removal and orientation of silk fibers. In the cytoplasmic process of the large and irregular nodule-forming cells surrounded by invaginations of the plasma membranes, numerous mitochondria and glycogen particles are contained. The maturational level of the nodule cells is perceived from the appearence of these cell inclusions. The secretory portion of the glands which porduce the secretory silk material shows two layers of the cells which are simple cuboidal epithelium and several connective layers. In the cytoplasm of the glandular epithelial cell, rough endoplasmic reticulums are well developed, and two types of secretory granules are observed. Between the adjacent epithelial cells, specialized septate junctions are formed along the plasma membranes.membranes.

• International Journal of Oral Biology
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• v.37 no.2
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• pp.77-83
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• 2012

We investigated the pulpal response to direct pulp capping in rat molar teeth using mineral trioxide aggregate (MTA) and calcium hydroxide (CH). A palatal cavity was prepared in rat maxillary molar teeth. Either MTA or CH was placed on the exposed pulp and all cavities were restored with composite. Rats were sacrificed for histological evaluation after 12 hours and at 2, 7, 14 and 21 days. In both the MTA and CH groups, reparative dentin formation was clearly observed on histology after 14 days. The MTA-capped pulps were found to be mostly free from inflammation, and hard tissue of a tubular consistent barrier was observed. In contrast, in CH-capped teeth, excessive formation of reparative dentin toward residual pulp was evident. The pulpal cell response beneath the reparative dentin layer was examined by immunofluorescence using antibodies against DSP. After 2 days, a few DSP immunopositive cells, most of which showed a cuboidal shape, appeared beneath the predentin layer. At 7 days, DSP-immunopositive cells with columnar odontoblast-like cells were seen beneath the newly formed hard tissues. At 14 and 21 days, DSP was more abundant in the vicinity of the odontoblastic process along the dentinal tubules than in the mineralized reparative dentin. The CH group showed strong expression patterns in terms of DSP immunoreactivity. Our results thus indicate that MTA may be a more effective pulp capping material as it induces the differentiation of odontoblast-like cells and the formation of reparative dentin without the loss of residual pulp functions.

• Applied Microscopy
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• v.28 no.3
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• pp.363-377
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• 1998

After the investigation on the eye of Incilaria fruhstorieri with light and electron microscopes, the following results were obtained. The eye of Incilaria fruhstorferi comprises cornea, lens, vitreous body, retina, and optic nerve inward from the outside. Cornea is composed of squamous, cuboid, columnar and irregular cells, which appear to be light due to their low electron density. In their cytoplasms, glycogen granules, multivesicular body, and nucleus were observed. Vitreous body, located behind non-cellular transparent lens, is filled with long and short microvilli protruding from the retinal epithelia. Retinal epithelium, the organ to perceive objects, is divided into four parts; microvillar layer pigment layer, nuclear layer, and neutrophils layer, from the apical portion. Microvillar layer consists of the type-I photoreceptor cells and pigmented granule cells. In the apical portion of their cytoplasms, long microvilli (length, $19{\mu}m$) , short microvilli (length, $8{\mu}m$), and rolled microvilli grow thick in the irregular and mixed forms. Photoreceptor cells are classified into type-I and type-II, according to their structures. The type-I cell has the apical portion rising roundly like a fan and the lower part which looks like the helve of a fan. In the cytoplasm of the apical portion, there are clear vesicles, cored vesicles, ovoid mitochondria, and microfilaments, and in the cytoplasm of the lower part, photic vesicles with their diameters about 60nm aggregate densely. The type-II photoreceptor cell, located at the lower end of the type-I cells, has a very large ovoid nucleus 3nd no microvilli. In the cytoplasm of the type-II cell, the photic vesicles with sizes 60nm aggregate more densely than in the cytoplasm of the type-I cell. Pigmented cells are classified into type-A and type-B, according to their structures. The type-A is identified to be a large cell containing round granules (diameter, $0.5{\mu}m$) of very high electron density, while the type-B is identified as a small cell where the irregular granules (diameter, $0.6{\mu}m$) of a little lower electron density amalgamate. Nuclear layer ranges from the bottom of pigment layer to the top of the capsule, and contains three kinds of nuclei (nuclei of the type-II photoreceptor cell, pigmented granule cell, and accessory neuron). The capsules covering the outmost part of the eyeball are composed of collagenous fiber and three longitudinal muscle layers (the thickness of each longitudinal muscle layer, $0.4{\mu}m$) and thick circular muscle layer (thickness, $0.3{\mu}m$). Around the capsules, there is a neurophile layer consisting of neurons and nerve fibers. Each neuron has a relatively large ovoid nucleus for its cytoplasm, and in the karyosome, large lumps of keterochromatin form a wheel nucleus.

• Journal of the Mineralogical Society of Korea
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• v.13 no.3
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• pp.115-120
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• 2000

Oxidation of pyrite has caused a serious environmental problem such as the acidification of soil and surface water. The mineralogical change of acid sulfate weathering of hydrothermally altered andesite which contained 11.8% of pyrite and was exposed in atmosphere by lay out works for a residential area and a golf course was studied using X-ray diffraction (XRD) and electronmicroscopes. Ferrihydrite, jarosite, and an unidentified water soluble phase were observed as weathering products of the andesite. Under electronmicroscopes, showed aggregate of platy microcrystals; jarosite was platy morphology: water soluble Phase was columnar. Morphology of fresh Pyrite in the andesite changed from pyritrohedron to cubic in its frequency with increasing its particle size. The drainage water was acidic (pH 3.5) and in an equilibrium state with both ferrihydrite and jarosite.

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.433-440
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• 2020

In this study, a new type of Durometer was invented by modifying the currently used Durometer with the hemisphere shaped needle to columnar shaped needle. The aim of the study is, hence, to provide the feasibility of the advanced Durometer for assessing setting time of the concrete. Generally, the finishing of concrete surface should be conducted to secure the smooth surface, improve the permeability, and prevent the plastic shrinkage cracking. Although this surface finishing work should be conducted during the plastic phase between initial and final setting, currently in practical situations, the timing of starting the finishing work was determined by the sense of the worker. To improve this situation, Kato Junji suggested to use the hemisphere and needle shaped Durometers to determine the initial and final setting time, respectively. However, in this case, there are difficulties of using two different Durometers and of occurring failure of the Durometer due to the intruded cement paste. To prove the feasibility of new typed Durometer, setting time and surface hardness were evaluated by applying for the concrete with various replacing ratios of fly-ash and coal gasification slag as an aggregate.