• Journal of the Korean Chemical Society
• /
• v.31 no.4
• /
• pp.352-358
• /
• 1987

Rate constants for the hydrolysis of para-substituted phenyl N-(p-chlorobenzoyl)chloroformimidate (I) derivatives in 1 : 4 dioxane-water at $25^{\circ}C$ have been determined. Rate data, substituent effect $(\rho\>{\rho}^+)$, product analysis and MO calculation indicate that the uncatalyzed reaction proceeds through an $S_N1$ mechanism involving the formation of azocarbonium ion (II) below pH 3.0, and the base-catalyzed reaction proceeds through an $S_N2$ mechanism via transition state (III) above pH 4.0. The relative stability of four peri planar conformational isomers were (E-ap) > (Z-ap) > (E-sp) > (Z-ap), respectively, and the most stable stereo structures shows that the Y-substituted phenyl group $(C_6H_4-Y)$ occupy vertical $(90^{\circ})$ position on the plane of the benzimidochloroformyl group in (E-ap) conformer. The nucleophilic substitution of water molecule occurs by sigma attack to the activatived azomethine carbon atom of (I) derivatives.

• Journal of the Korean Chemical Society
• /
• v.22 no.3
• /
• pp.164-172
• /
• 1978

Carboxypeptidase A-catalyzed hydrolysis of ester substrates was carried out at room temperature in the presence of a number of external reagents. If the acyl-enzyme intermediate, an anhydride, is attacked by the external reagents, products formed by trapping at the acyl portion or at the enzyme portion of the anhydride group can be obtained. Examination of the uv/vis spectral properties of the reaction products and of changes in enzyme activity indicated that such trapping reactions did not occur. Also performed was evaluation of enzymatic rate parameters for the the hydrolysis of O-(o-hydroxyphenylacetyl)-L-${\beta}$-phenyllactate. Detection of 2-coumaranone possibly formed by attack of the o-hydroxy group as an intramolecular trapping group at the acyl-enzyme intermediate was tried, but no evidences for the intramolecular trapping reaction were obtained. Failure to trap the intermediate was discussed in terms of steric hindrance imposed on the approach of the trapping reagents to the anhydride group of the acyl-enzyme intermediate and of the fast enzymatic breakdown of the intermediate.

• Journal of Korean Neurosurgical Society
• /
• v.47 no.2
• /
• pp.119-123
• /
• 2010

Objective : Aneurysmal rebleeding is a major cause of death and disability. The aim of this study is to investigate the incidence of rebleeding, and the factors related with patient's outcome. Methods : During a period of 12 years, from September 1995 to August 2007, 492 consecutive patients with aneurysmal subarachnoid hemorrhage (SAH) underwent surgery at our institution. We reviewed the patient's clinical records, radiologic findings, and possible factors inducing rebleeding. Also, we statistically analyzed various factors between favorable outcome group (FG) and unfavorable outcome group (UG) in the rebleeding patients. Results : Rebleeding occurred in 38 (7.7%) of 492 patients. Male gender, location of aneurysm (anterior communicating artery) were statistically significant between rebleeding group and non-rebleeding group (p=0.01 and p=0.04, respectively). Rebleeding occurred in 26 patients (74.3%) within 2 hours from initial attack. There were no statistically significant factors between FG and UG. However, time interval between initial SAH to rebleeding was shorter in the UG compared to FG (FG=28.71 hrs, UG=2.9 hrs). Conclusion : Rebleeding occurs more frequently in the earlier period after initial SAH. Thus, careful management in the earlier period after SAH and early obliteration of aneurysm will be necessary.

• Journal of Ginseng Research
• /
• v.46 no.4
• /
• pp.585-591
• /
• 2022

Background: Korean Red Ginseng (KRG) extract has been shown to have beneficial effects in patients with atherosclerosis, suggesting that KRG extract may be effective in preventing subsequent ischemic stroke in patients with severe atherosclerosis. Methods: This double-blind, placebo-controlled trial randomized patients with severe atherosclerosis in major intracranial arteries or extracranial carotid artery, to ginseng group and placebo group. They were given two 500-mg KRG tablets or identical placebo tablets twice daily for 12 months according to randomization. The primary endpoint was the composite of cerebral ischemic stroke and transient ischemic attack during 12 months after randomization. The secondary endpoints were change in volumetric blood flow of the intracranial vessels and the incidence of newly developed asymptomatic ischemic lesions. Any adverse events were monitored. Results: Fifty-eight patients were randomized from June 2016 to June 2017, 29 to ginseng and 29 to placebo, and 52 (28 and 24, respectively) completed the study. One patient in the placebo group, but none in the ginseng group, experienced ischemic symptoms (p = 0.46). Changes in volumetric blood flow and the presence of ischemic brain lesions did not differ significantly in the two groups, and none of these patients experienced adverse drug reactions. Conclusion: Ginseng was well tolerated by patients with severe atherosclerosis, with these patients showing good compliance with ginseng dosing. Ginseng did not show significant effects compared with placebo, although none of the ginseng-treated patients experienced ischemic events. Long-term studies in larger patient populations are required to test the effect of ginseng.

• Journal of Chest Surgery
• /
• v.55 no.6
• /
• pp.462-469
• /
• 2022

Background: Carotid endarterectomy (CEA) is used to treat carotid stenosis, which is associated with cerebral infarction and may result in neurologic deficits such as stroke, transient ischemic attack (TIA), and local nerve injury. To decrease surgery-related complications and improve patient satisfaction with esthetic outcomes, efforts have been made to minimize incision size instead of using a standard longitudinal incision. Methods: We performed a retrospective analysis of 151 cases of CEA, of which 110 used conventional incisions and 41 used high mini-skin incisions (HMIs), from March 2015 to December 2021 at a single institution. Short-term (30-day) postoperative results were evaluated for rates of mortality, stroke, TIA, and cranial/cervical nerve injuries. Risk factors for nerve injury were also assessed. Results: The HMI group showed significantly (p<0.01) shorter operative and clamp times than the conventional group. The HMI group also had significantly shorter incision lengths (5.3±0.9 cm) than the conventional group (11.5±2.8 cm). The rates of stroke, TIA, and death at 30 days were not significantly different between the 2 groups. There was no significant difference in the rate of cranial and cervical nerve injuries, and all injuries were transient. A high lesion level (odds ratio [OR], 9.56; 95% confidence interval [CI], 3.21-28.42; p<0.01) and the clamp time (OR, 1.07; 95% CI, 1.03-1.12; p<0.01) were found to be risk factors for nerve injuries. Conclusion: Use of the HMI in CEA for carotid stenosis was advantageous for its shorter operative time, shorter internal carotid artery clamp time, reduced neurologic complications, and improved esthetics.

• Animal Systematics, Evolution and Diversity
• /
• v.36 no.1
• /
• pp.17-24
• /
• 2020

Doryctinae is a large and heterogeneous group with more than 1,000 described. It is idiobiont ectoparasitoids on the larvae of wood-boring and xylophagous beetles. Some species attack larvae of wood boring lepidoptera. In the present study, fifteen species belonging to eight genera of the subfamily Doryctinae are recorded for the first time from Korea: Doryctes Haliday (2 species), Eodendrus Belokobylskij (1 species), Heterospilus Haliday (4 species), Monolexis Förster (1 species), Neurocrassus Snoflak (2 species), Rhoptrocentrus Marshall (1 species), Sonanus Belokobylskij et Konishi (1 species), Spathius Nees (3 speices). The genera Eodendrus Belokobylskij, Monolexis Förster, Rhoptrocentrus Marshall, Sonanus Belokobylskij et Konishi and fifteen species are reported for the first times from Korea. Diagnosis and host information are provided.

• Textile Coloration and Finishing
• /
• v.1 no.1
• /
• pp.26-34
• /
• 1989

The selective chemical degradation or etching of PET based on an organic amine attack on the ester group. The techniques involves the chemical removal of loss ordered amorphous regions or crystalline regions, which are essentially unaffected by the degradative etchant. Thus, most of previous studies have limited to consideration which has been given to structural changes taking place. Therefore, this study was carried out to investigate surface characterization, dyeing properties of PET film hydrazinolyzed with hydrazine hydrate in methanol. PET film was treated with 30% hydrazine hydrate in methanol at $30^\circ{C}$ for various time intervals. The total surface tension of treated PET increased, the dispersion force decreased and the hydrogen bonding force increased. The equilibrium dye adsorption, dyeing rate and apparent diffusion coefficient of acid dyes increased, and the apparent activation energies of diffusion decreased.

• Journal of the Korean Applied Science and Technology
• /
• v.19 no.3
• /
• pp.161-166
• /
• 2002

The alkaline hydrolysis of alkyl alkylphosphinate and alkyl phenylphosphinates have been studied at room temperature. The hydrolysis proceeded as an one-stage reaction($S_{N}$ 2) and involved a nucleophilic attack of the hydroxyl ion on the phosphorus atom. And the length of the alkoxy group in the phosphinate esters affected on hydrolysis. Therefore, the alkaline hydrolysis may be used as a method to decompose the chemical agents.

• The Journal of the Korean life insurance medical association
• /
• v.29 no.1
• /
• pp.7-11
• /
• 2010

Anxiety disorders Anxiety disorders are among the most prevalent mental disorders in the general population. Anxiety disorders can be viewed as a family of related but distinct mental disorders, which include following as classified in the text revision of fourth edition of Diagnostic and Statistical Manual Disorders(DSM-IV-TR): (1) panic disorder with or without agoraphobia; (2) agoraphobia with or without panic disorder; (3) specific phobia; (4) social phobia; (5) obsessive-compulsive disorder; (6) posttraumatic stress disorder; (7) acute stress disorder; (8) generalized anxiety disorder. An acute intense attack of anxiety accompanied by feeling of impending doom is known as panic disorder. The term phobia refer to an excessive fear of a specific object, circumstance, or situation. Obsessivecompulsive disorder is represented by a diverse group of symptoms that include intrusive thoughts, rituals, preoccupations, and compulsions. Posttraumatic stress disorder is a condition marked by development of symptoms after exposure to traumatic life events. Generalized anxiety disorder is defined as excessive anxiety and worry about several events or activities for most days during at least a 6-month period.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.487-488
• /
• 2008

SiOC films containing alkyl groups have a low dielectric constant because of the interaction between the C-H hydrogen bonds and the oxygen of high electro-negative atom. The Si-$CH_3$ in a void is broken by the $O_2$, therefore the strength of CH bond in Si-O-O-$CH_3$ bond increases. The Si-O-O-$CH_3$ bond is broken by nucleophilic attack due to Si atom, again. The elongation of C-H bond causes the red shift, and the compression of C-H bond causes the blue shift. Among these chemical shifts, the blue shift from $1000\;cm^{-1}$ to $1250\;cm^{-1}$ was related with the formation of pores. If the oxygen is deficient condition, the methylradicals of the electron-rich substitution group terminate easily the Si-O-Si cross-link, and the pore is originated from the cross-link breakdown due to much methyl radicals of Si-$CH_3$. The dielectric constant of the films decreases due to pore generation.