• The Korean Journal of Ceramics
• /
• 제7권2호
• /
• pp.70-73
• /
• 2001

Phase transformation of TiSi$_2$ confined in sub-micron area of which the size is around or smaller than the grain size of C49 TiSi$_2$ phase is studied. It has been known that the C49 to C54 phase change is massive transformation that occurs abruptly starting from C54 nuclei located at triple point grain boundaries of C49 phase. When the C49 phase is confined in sub-micron area, however, the massive phase transformation is observed to be hindered due to the lack of the triple point grain boundaries of C49 phase. Heat treatment at higher temperatures starts to decompose the C49 phase, and the resulting decomposed Ti atoms diffuse to, and react with, the underneath Si material to form C54 phase that exhibits spherical interface with silicon. The newly formed C54 grains can also trigger the massive phase transformation to convert the remaining undecomposed C49 grains to C54 grains by serving as nuclei like conventional C54 nuclei located at triple point grain boundaries.

• The Journal of the Korean dental association
• /
• 제10권1호
• /
• pp.29-33
• /
• 1972

The author has studied histochemically on the giant cells appeqring in the 10 giant cell lesions which had been collected from the biopsies at the deaprtment of oral pathology, college of dentistry, Seoul national university and dental sections of several hospitals in Seoul. The results obtained were as follows: 1. The giant cells varied in size had 2 to 10 nuclei without any mitotic figures. 2. The giant cells showed high granularity in cytoplasm, extreme irregularity in outline of nuclear and cytoplasmic membrane, and very large and prominent nucleoli. 3. The giant cells were reacted moderately by Periodic Acid-Schiffraction. 4. The chtoplams of giant cells were stained moderately of deeply with Pyronin, and their nuclei with Methyl green. 5. In the sections stained with Iron-Hematoxylin, the giant cells showed microvacules and fine granular type mitochondria aggregated close to nuclei but not phagocytosed materials.

• Phonetics and Speech Sciences
• /
• 제6권4호
• /
• pp.109-115
• /
• 2014

Fricated nuclei in Nuosu Yi were found to be more correctly described as fricated vowels, rather than syllabic fricatives due to the presence of clear formant structures typical of front vowels. In this exploratory study, two types of fricated nuclei were examined: retroflex "yr" and non-retroflex "y". The retroflex nucleus "yr" had higher F1 and lower F3 than non-retroflex "y", indicating a lower tongue height. On the other hand, F2 was found to correlate not with nucleus retroflexion, but instead with onset consonant retroflexion: F2 was higher following retroflex onsets, in both vowels. This effect was persistent through the entire vowel, suggesting a phonological effect, rather than a coarticulatory one. Interpretation of the F2 results require accompanying articulatory data since the usual coupling of F2 and tongue backness does not always hold for retroflex vowels. Examining the articulation of the fricated nuclei in Nuosu Yi is a direction for future research.

• Nuclear Engineering and Technology
• /
• 제53권5호
• /
• pp.1612-1618
• /
• 2021

The fusion-barrier distribution is very sensitive to the structure of the colliding nuclei such as nuclear quadrupole and hexadecapole deformation parameters and their signs. If the nuclei that enter the fusion reaction are deformed, the barrier problem becomes complicated. Therefore the deformation parameters are taken into account in the calculations. In this study, Neuro-Fuzzy approach, ANFIS, method has been used for the estimation of ground-state quadrupole (𝜀₂) and hexadecapole (𝜀₄) deformation parameters for the nuclei. According to the results, the method is suitable for this task and one can confidently use it to obtain the data that is not available in the literature.

• Journal of The Korean Society of Clinical Toxicology
• /
• 제20권1호
• /
• pp.31-34
• /
• 2022

Cerebellar Hippocampal and Basal Nuclei Transient Edema with Restricted diffusion (CHANTER) syndrome is characterized by an altered mental status. The acute MRI lesions show abnormal restricted diffusion imaging bilaterally and symmetrically in the cerebellum, hippocampus, and basal nuclei. This syndrome is an unknown syndrome and is presumed to be mainly an opioidinduced toxidrome. Here, we present a case study wherein we show that it can also be caused by an antidepressant overdose.

• Proceedings of the KSAR Conference
• /
• 한국동물번식학회 2001년도 춘계학술발표대회
• /
• pp.15-15
• /
• 2001

We recently demonstrated that satellite regions exhibit an aberrant DNA methylation in cloned bovine embryos. Here, we examined, using bisulfite -sequencing technology, whether the inefficient demethylation of cloned donor genomes could be rescued by the presence of oocytic nuclei. Both AciI digestion and sequencing analyses showed that satellite sequence was demethylated more efficiently in cloned tetraploid blastocysts than in diploid clones. When methyl -CpG density (the number of methyl-CpG sites per string) was scored, a significant decrease was observed In tetraploids (P<0.001). These results suggest that unknown mechanisms provided by oocytic nuclei could assist the demethylation of satellite sequences in tetraploid clones.

• Journal of Astronomy and Space Sciences
• /
• 제36권1호
• /
• pp.21-33
• /
• 2019

This paper focuses on the interpretation of radiation fluxes from active galactic nuclei. The advantage of positron annihilation spectroscopy over other methods of spectral diagnostics of active galactic nuclei (therefore AGN) is demonstrated. A relationship between regular and random components in both bolometric and spectral composition of fluxes of quanta and particles generated in AGN is found. We consider their diffuse component separately and also detect radiative feedback after the passage of high-velocity cosmic rays and hard quanta through gas-and-dust aggregates surrounding massive black holes in AGN. The motion of relativistic positrons and electrons in such complex systems produces secondary radiation throughout the whole investigated region of active galactic nuclei in form of cylinder with radius R= 400-1000 pc and height H=200-400 pc, thus causing their visible luminescence across all spectral bands. We obtain radiation and electron energy distribution functions depending on the spatial distribution of the investigated bulk of matter in AGN. Radiation luminescence of the non-central part of AGN is a response to the effects of particles and quanta falling from its center created by atoms, molecules and dust of its diffuse component. The cross-sections for the single-photon annihilation of positrons of different energies with atoms in these active galactic nuclei are determined. For the first time we use the data on the change in chemical composition due to spallation reactions induced by high-energy particles. We establish or define more accurately how the energies of the incident positron, emitted ${\gamma}-quantum$ and recoiling nucleus correlate with the atomic number and weight of the target nucleus. For light elements, we provide detailed tables of all indicated parameters. A new criterion is proposed, based on the use of the ratio of the fluxes of ${\gamma}-quanta$ formed in one- and two-photon annihilation of positrons in a diffuse medium. It is concluded that, as is the case in young supernova remnants, the two-photon annihilation tends to occur in solid-state grains as a result of active loss of kinetic energy of positrons due to ionisation down to thermal energy of free electrons. The single-photon annihilation of positrons manifests itself in the gas component of active galactic nuclei. Such annihilation occurs as interaction between positrons and K-shell electrons; hence, it is suitable for identification of the chemical state of substances comprising the gas component of the investigated media. Specific physical media producing high fluxes of positrons are discussed; it allowed a significant reduction in the number of reaction channels generating positrons. We estimate the brightness distribution in the ${\gamma}-ray$ spectra of the gas-and-dust media through which positron fluxes travel with the energy range similar to that recorded by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) research module. Based on the results of our calculations, we analyse the reasons for such a high power of positrons to penetrate through gas-and-dust aggregates. The energy loss of positrons by ionisation is compared to the production of secondary positrons by high-energy cosmic rays in order to determine the depth of their penetration into gas-and-dust aggregations clustered in active galactic nuclei. The relationship between the energy of ${\gamma}-quanta$ emitted upon the single-photon annihilation and the energy of incident electrons is established. The obtained cross sections for positron interactions with bound electrons of the diffuse component of the non-central, peripheral AGN regions allowed us to obtain new spectroscopic characteristics of the atoms involved in single-photon annihilation.

• The Korean Journal of Physiology and Pharmacology
• /
• 제1권3호
• /
• pp.275-284
• /
• 1997

Unilateral labyrinthectorny (ULX) causes autonomic symptoms, ocular and postural asymmetries, which disappear over tune in the process of equilibrium recovery known as vestibular compensation. In the present study in order to elucidate mechanisms responsible for the effects of electrical stimulation on vestibular compensation and investigate the relationship between vestibular compensation and c-Fos expression in the medial vestibular nuclei following ULX, we measured spontaneous nystagmus, eye movement induced by sinusoidal rotation and c-Fos expression or to 72 hs after ULX in Sprague-Dawley rats. Experimental animals were divided into two groups: ULX group with ULX only, and electrical stimulation (ES) group with electrical stimulation of $-2{\sim}-5V$, 1.0ms, 100 Hz to the lesioned vestibular system for 4 hs/day. Spontaneous nystagmus following ULX disappeared by 72 hs in ULX group and 36 hs in ES group. In eye movement induced by sinusoidal rotation, normal pattern of eye movement by rotation toward the lesioned side was recovered 24 hs after ULX at rotation of 0.1 Hz and 6 hs after at 0.2 Hz, 0.5 Hz in ULX group. In ES group, the eye movement recovered after 12 hs at 0.1 Hz, 6 hs at 0.2 Hz, and 4 hs at 0.5 Hz. Directional Preponderance which represents the symmetry of bilateral vestibular functions showed significantly early recovery in ES group compared with that of ULX group. Expression or c-Fos immunoreactive cells in the bilateral medial vestibular nuclei was severely asymmetrical till 36 hs in ULX group, and then it became a symmetry and disappeared after 72 hs. However, ES group showed the symmetry of c-Fos expression after 6 hs, which was significantly early recovery in 25 group. All these findings suggest that electrical stimulation ameliorates recovery of vestibuloocular reflex following ULX by the restoration of the balance of the resting activity between bilateral medial vestibular nuclei. In addition, c-Fos expression in the medial vestibular nuclei could be used as a marker of vestibular compensation since c-Fos expression is closely related to the course of recovery following ULX.

• Journal of the Korean Magnetic Resonance Society
• /
• 제21권4호
• /
• pp.131-134
• /
• 2017

Proton detected Heteronuclear Multiple Quantum Coherence (HMQC) and Heteronuclear Single Quantum Coherence (HSQC) essentially provide the same information - correlation of the chemical shift of the proton to J-coupled hetero nuclei such as $^{13}C$ or $^{15}N$ nuclei. This paper is a practical note for the students who ask which one is better and which methods they use routinely. Artifact suppression using phase cycling and gradient pulses are discussed.

• Journal of the Korean Ceramic Society
• /
• 제32권1호
• /
• pp.90-94
• /
• 1995

In Sr-ferrite system, it has been attempted to inhibit the abnormal grian growth using Sr-ferrite powders synthesized by molten salt method as the matrix and the seeds, respectively. At each sintering temperature, the addition of seed more than 15% suppressed the abnormal grain growth, and the uniform microstructure resulted. Particularly, at 12$25^{\circ}C$, it was observed that the maximum number of the abnormal grain growth nuclei was achieved since the abnormal grain growth was suppressed even by the addition of 10% seed.