• Journal of Environmental Science International
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• v.7 no.5
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• pp.599-605
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• 1998

The purpose of this work was to examine whether X-Y chromosome dissociation in the primary spermatocytes of mice could be used as an in vivo short-term assaying system that detect environmental mutagens. Four alkylating agents(EMS, MMS, MMC and MNNG) which were known as strong mutagens were administered to BALB/c male mice 3-4 months old. In the control group, the mean frequencies of previously dissociated X and Y chromosomes and autosomes were 7.17% and 2.12%, respectively. Compared to the control group, mutagen-treated groups have no significant differences in dissociation rate of autosomes, while these poops were about 1.2-2.5 times higher in the frequencies of X-Y dissociation. Generally, X-Y dissociation frequency increased consistently with the concentration of mutagens whereas the tendency of autosome dissociation frequency was variable among several mutagens. These results suggest that X-Y dissociation in the primary spermatocytes of mice is applicable as an vivo short-term assaying system for environmental mutagens. There were significantly distinct increase in dissociation of X-Y chromosome in both the hybrid and parents but the X-Y previous dissociation of hybrid appeared higher frequency than BALB /c and wild mice. These results indicate that the factor related to binding X-Y chromosome is specific to strains.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1285-1293
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• 2014

Several interesting features in trajectory were observed in the direct dynamics study of formaldehyde dissociation above radical dissociation limit. The hydrogen atom deliberately placed on the radical dissociation path can turn around at some distance from C without completion of dissociation and return to HCO moiety, colliding with it just as in a radical-radical recombination and producing a highly energized molecule. Excursion of a hydrogen atom to a distance of 6-8 bohrs and migration of a hydrogen atom back and forth between C and O are two of the most interesting features exhibited by the energized molecule. A series of excursions is seen to lead to a different kind of dissociation resembling roaming-like dissociation characterized by high vibrational excitation of $H_2$ fragment. It is suggested that excursion occurs due to involvement of two different force field systems that exhibit discontinuity in 6-8 bohrs from HCO moiety. We argue that roaming is a non-zero impact parameter version of the excursion.

• Anxiety and mood
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• v.7 no.1
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• pp.29-33
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• 2011

Objective : This study was performed to analyze the relationship between posttraumatic stress, coping style, and dissociation in Korean firefighters. Methods : Subjects included 193 male and 9 female firefighters in the metropolitan city of Daejeon. Their age ranged from 25 to 57 with an average of 39.17 (SD : 7.572) years. Their posttraumatic stress or traumatic experiences were assessed with the Korean Version of the Posttraumatic Stress Diagnostic Scale. Their coping style was categorized with the Korean version of the Ways of Coping Checklist. Their dissociation was assessed with the Korean version of Dissociative Experiences Scale. The data analysis included a correlation analysis and structural equation modeling. The modeling tested the validity of the model that posttraumatic stress had a direct effect on dissociation and coping style had an mediatory effect between stress and dissociation. Results : First, firefighters' posttraumatic stress or traumatic experiences had a direct effect on dissociation, a symptom of a mental disorder. Second, the firefighters employed passive styles to cope with their stress. This is explained that they had been exposed to their traumatic events repeatedly without being able to control it themselves. Third, coping style had no effect on the mediation between posttraumatic stress and dissociation. This is explained in terms of repeated exposure to the traumatic events. Conclusion : Based on the results, it is concluded that Korean firefighters' dissociation was not relieved by their coping effort but associated directly with their traumatic experiences. To decrease their dissociation, it is necessary to reduce the exposure to their traumatic events.

• Toxicological Research
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• v.11 no.1
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• pp.51-55
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• 1995

The present experiment was carried out to investigate whether X and Y chromosome dissociation in the primary spermatocytes of mice can be used as an in vivo assaying system that detect environmental mutagens. For this purpose, alkylating agents (EMS, MMS and MMC), which are strong mutagens, were administered to ICR male mice 12-15 weeks old. The mean frequencies of previously dissociated X-Y chromosomes and autosomes of the control group were 7.34-7.45% and 0.92-1.04%, respectively. The frequencies of X-Y dissociation in the mutagen-treated groups with 10.0 mM EMS and 5.0 mM MMS were about 3.3-4.6 times higher than that in the control group, but there were no significant differences in dissociation of autosomes in both the control and the mutagen-treated groups. These results suggest that X-Y dissociation in the primary spermatocytes of mice can be used as an in vivo short-term assaying system for environmental mutagens.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1029-1035
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• 2014

The protolytic dissociation process of hydrochloric acid (HCl) and hydrofluoric acid (HF) is studied using the B3LYP and MP2 methods with the 6-311+G(d,p) basis set in the gas phase and in aqueous solution. To study the phenomena in detail, discrete and discrete/continuum models were applied by placing water molecules in various positions around the acid. The dissociation process was studied using the thermodynamic cycle involving the structures optimized both in the gas phase and in aqueous solution and was analyzed with two key energy factors, relaxation free energy (${\Delta}G_{Rex(g)}$) and solvation free energy (${\Delta}G_s$). Based on the results, we could understand the dissociation mechanism and wish to propose the best way to study acid dissociation process using the CPCM methodology in aqueous solution.

• PNF and Movement
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• v.20 no.1
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• pp.51-58
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• 2022

Purpose: The purpose of this study was to investigate the effect of thoracic-lumbar dissociation motion and slump motion on thoracic-lumbar erector spinae and rectus abdominis muscle activity. Methods: Seventeen healthy adult volunteers participated in this study. All participants performed two motions (thoracic-lumbar dissociation motion, slump motion). Muscle activation during the two motions was measured using a surface electromyography device. The data from this were collected from the iliocostalis thoracis, iliocostalis lumborum, and rectus abdominis. The activities of these muscles before and after each motion were then compared. Results: The iliocostalis thoracis activation was significantly greater during the thoracic-lumbar dissociation motion than during the slump motion (p <0.05). The iliocostalis lumborum activation was greater during the slump motion than during the thoracic-lumbar dissociation motion (p <0.05). The rectus abdominis activation was lesser during the slump motion than during the thoracic-lumbar dissociation motion (p <0.05). Conclusion: This study confirmed that individual contraction of the erector spinae muscles is possible during thoracic-lumbar dissociation motion, which increases the stability of the thoracic spine. In addition, this motion could improve control of the rectus abdominis. Therefore, thoracic-lumbar dissociation motion should be considered for rehabilitation programs for patients with kyphosis and back pain.

• Mass Spectrometry Letters
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• v.13 no.4
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• pp.177-183
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• 2022

The monomer and dimer structures of the amyloid fragment Aβ(1-16) sequence formed in H₂O were investigated using electrospray ionization mass spectrometry (MS) and tandem MS (MS/MS). Aβ16 monomers and dimers were indicated by signals representing multiple proton adduct forms, [monomer+zH]ⁿ⁺ (=M^z+, z = charge state) and [dimer+zH]^z+ (=D^z+), in the MS spectrum. Fragment ions of monomers and dimers were observed using collision-induced dissociation MS/MS. Peptide bond dissociation was mostly observed in the D1-D7 and V11-K16 regions of the MS/MS spectra for the monomer (or dimer), regardless of the monomer (or dimer) charge state. Both covalent and non-covalent bond dissociation processes were indicated by the MS/MS results for the dimers. During the non-covalent bond dissociation process, the D³⁺ dimer complex was separated into two components: the M¹⁺ and M²⁺ subunits. During the covalent bond dissociation of the D³⁺ dimer complex, the b and y fragment ions attached to the monomer, (M+b_10-15)^z+ and (M+y_9-15)^z+, were thought to originate from the dissociation of the M²⁺ monomer component of the (M¹⁺+M²⁺) complex. Two different D³⁺ complex geometries exist; two distinguished interaction geometries resulting from interactions between the M¹⁺ monomer and two different regions of M²⁺ (the N-terminus and C-terminus) are proposed. Intricate fragmentation patterns were observed in the MS/MS spectrum of the D⁵⁺ complex. The complicated nature of the MS/MS spectrum is attributable to the coexistence of two D⁵⁺ configurations, (M¹⁺+M⁴⁺) and (M²⁺M³⁺), in the Aβ16 solution.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.4
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• pp.197-201
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• 2001

The influence of argon, oxygen, and nitrogen admixtures on the dissociation of $Cl_2$ molecules in a glow discharge low-temperature plasma under the constant pressure conditions was investigated. For $Cl_2/Ar$ and $Cl_2/O_2$mixtures, the concentration of chlorine atoms was observed to be a practically constant at argon or oxygen concentrations up to 50%. This invariability is a most pro bably explained by relative increase in rate of $Cl_2$ direct electron impact dissociation due to the changes in electrophysical parameters of plasma such as EEDF, electron drift rate and mean energy. For all the considered mixtures, the contribution of stepwise dissociation involving active species from gas additives (metastable atoms and molecules, vibrationally excited molecules) was found to be negligible.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.399-404
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• 2008

The influence of gas hydrate dissociation on submarine slope stability was studied in this paper. Gas hydrates are stable under high pressure and low temperature conditions. Once gas hydrate dissociates due to natural or human activities, it generates large amount of gas and water. During gas hydrate dissociation, a pore pressure between soil particles increases and results in the loss of an effective stress and degradation of soil stiffness. A pore pressures model was proposed to calculated excess pore pressures generated by gas hydrate dissociation at the Storegga Slide. A slope stability analysis for the Storegga Slide using a two dimensional finite difference method was carried out by considering excess pore pressures due to gas hydrate dissociation. Since the excess pore pressure calculated by the proposed method resulted in the considerable loss of stiffness and strength in slope, a submarine slope failure occurred at the Storegga slide was well simulated.

• BMB Reports
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• v.38 no.5
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• pp.533-538
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• 2005

The kinetics of thermal dissociation of superoxide dismutase (SOD) was studied in 0.05 M Tris-HCl buffer at pH 7.4 containing $10^{-4}\;M$ EDTA. The number of conformational locks and contact areas and amino acid residues of dimers of SOD were obtained by kinetic analysis and biochemical calculation. The cleavage bonds between dimers of SOD during thermal dissociation and type of interactions between specific amino acid residues were also simulated. Two identical contact areas between two subunits were identified. Cleavage of these contact areas resulted in dissociation of the subunits, with destruction of the active centers, and thus, lost of activity. It is suggested that the contact areas interact with active centers by conformational changes involving secondary structural elements.