• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.11 no.1
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• pp.48-55
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• 2001

The purpose of this study was to evaluate the analytical accuracy and precision of microwave oven digestion/atomi absorption spectrophotometry (AAS) for analyzing airborne chromium collected on mixed cellulose ester membrane (M filter from the work environment, and to compare the accuracy and the precision with those of the National Institute for Occupational Safety and Health (NIOSH) Method #7024 hot plate digestion/AAS method. For this study, field air sample pairs were collected from a electroplating process, and spiked samples in a laboratory were prepared and using these samples. Two digestion methods were comp; and evaluated in terms of recovery rate and bias as indices of accuracy and coefficient of variation as a index of precision. The results and conclusions are as follows. In spiked samples, the accuracies (% mean recoveries) of hot plate/AAS and microwave oven/AAS method were 97.19%, 97.1%, respectively, and the precisions (pooled respectively, and the precisions (pooled coefficient of variance, $CV_{pooled}$) 6.93% and 3.88%, respectively. The biases of hot plate ani microwave oven methods were 4.56 - 14.7% and 2.22 - 7.42% respectively. There was no statistically significant difference between hot plate and microwave oven methods recovery rates of spiked samples (p>0,05). Also, no statistically significant difference was shown among the concentrations of air samples determined by two method (p>0.05). In conclusion, microwave oven/AAS method h excellent accuracy and precision, and advantages such as time-saving and simple procedure in comparison with the classical NIOSH method. Therefore, this method can be use widely to analyze airborne chromium collected on MCE filter from the work environments.

• The Korean Journal of Pain
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• v.14 no.2
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• pp.193-198
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• 2001

Background: Anterior atlantoaxial subluxation (AAS) is a frequent phenomenon in rheumatoid arthritis (RA). AAS compresses the C2 ganglion or nerve and is a cause of posterior neck pain or occipital headache. Methods: We selected RA patients that had developed posterior neck pain or occipital headache caused by AAS. AAS was diagnosed by an increase of ADI (atlantodental interval). A distance of 3 mm or more was considered significant. Patients with vertical subluxation or symptoms suggestive of myelopathy were excluded. Before C2 RF ganglionotomy, we proceeded with a C2 ganglion block or greater occipital nerve block used by local anesthetics. For C2 RF ganglionotomy, the patient was placed in the supine position on a fluoroscopic table. A 100 mm, 4 mm active tip electrode was chosen. Following sensory stimulation at 0.2 to 0.6 V, the lesion was performed at a temperature of $60^{\circ}C$ to $65^{\circ}C$ for 60 sec. We followed up the patient after 6 months later. Results: All cases were female and the average duration of RA was 8.5 years. The duration of posterior neck pain or occipital headache was 1-8 months. The average ADI was 4.2 mm and the McGregor index was 3.3 mm on the average. In all cases, the score on the 4 point Likert scale was 4 (pain free) during the follow-up period. Conclusions: We found that the occipital headache or posterior neck pain caused by AAS in rheumatoid arthritis patients was alleviated over a short term follow up. C2 RF ganglionotomy is suggested as an effective palliative treatment for AAS in RA patients.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.3
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• pp.191-200
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• 2014

We investigated the anxiolytic-like activity of ${\alpha}$-asarone (AAS) from Acorus gramineus in an experimental rat model of anxiety induced by repeated administration of the exogenous stress hormone corticosterone (CORT). The putative anxiolytic effect of AAS was studied in behavioral tests of anxiety, such as the elevated plus maze (EPM) test and the hole-board test (HBT) in rats. For 21 consecutive days, male rats received 50, 100, or 200 mg/kg AAS (i.p.) 30 min prior to a daily injection of CORT. Dysregulation of the HPA axis in response to the repeated CORT injections was confirmed by measuring serum levels of CORT and the expression of corticotrophin-releasing factor (CRF) in the hypothalamus. Daily AAS (200 mg/kg) administration increased open-arm exploration significantly in the EPM test, and it increased the duration of head dipping activity in the HBT. It also blocked the increase in tyrosine hydroxylase (TH) expression in the locus coeruleus (LC) and decreased mRNA expression of brain-derived neurotrophic factor (BDNF) and its receptor, TrkB, in the hippocampus. These results indicated that the administration of AAS prior to high-dose exogenous CORT significantly improved anxiety-like behaviors, which are associated with modification of the central noradrenergic system and with BDNF function in rats. The current finding may improve understanding of the neurobiological mechanisms responsible for changes in emotions induced by repeated administration of high doses of CORT or by elevated levels of hormones associated with chronic stress. Thus, AAS did exhibit an anxiolytic-like effects in animal models of anxiety.

• Journal of Soil and Groundwater Environment
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• v.22 no.6
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• pp.22-28
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• 2017

The accuracy of analytical results in response to the use of different additives ($NH_4Cl$, KCl, $LaCl_3$) and oxidant gases was evaluated and compared by using Atomic Absorption Spectrometry (AAS). Identification of spectroscopic interferences and possible improvements in Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) analysis were also discussed. The average accuracies of total chromium using Certified Reference Materials (CRMs) were found to be 72.1~94.2% in air/acetylene flame condition by AAS, and they were improved to 100.5~110.5% when the oxidants was changed to nitrous oxide rather than adding the additives. The field samples showed similar trends to CRMs, but chromium concentrations were highly variable depending on analytical conditions. The average accuracies using CRMs were estimated to be 89.3~166.1% by ICP-AES, and improved to below 121.7% after eliminating iron interference. Field samples with low chromium and high iron concentration were measured to be > 30% lower in total chromium concentrations by ICP-AES than AAS in nitrous oxide/acetylene flame. Total chromium concentrations in soil could be analyzed with better accuracy under nitrous oxide/acetylene flame by AAS because it was more effective to increase the temperature of the flame than to eliminate the chemical interference for maximizing atomization of chromium. When using ICP-AES, interference substances, total chromium levels, and analytical conditions should be also considered.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.1
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• pp.47-53
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• 2011

The artificial aggregates (AAs) were manufactured from the parent batch powders consisting of bottom ash containing excess unburned carbon and dredged soil, 7 : 3 weight ratio by direct sintering method and those physical properties were evaluated. Especially, the effects of waste glass or frit (NWG) which was made by addition of 5 wt% $Na_2O$ to the waste glass upon the bloating phenomenon of AAs were analyzed. The AAs manufactured from the parent batch powders showed a lower specific gravity than that of specimens containing waste glass or NWG due to excess u$Na_2O$nburned carbon which usually obstructs a sintering process. But, the waste glass added on parent batch powders promoted the sintering and densification thus increased the specific gravity of AAs. Also the specific gravity of AAs added with 5 wt% NWG, was lowered compared to that of AAs added with as-received waste glass. This is because of bloating of shell which captures gases owing to the lowered viscosity of liquid formed at the specimen surface caused by $Na_2O$ addition. In conclusion, the AAs sintered at above $1100^{\circ}C$ in this study showed characters of lightweight aggregate of specific gravity 1.15~1.34 and water absorption 11~19 %, and the bloating phenomenon of AAs was occurred at the shell rather black core part.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.2
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• pp.63-69
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• 2012

Recently, the cement industries brought very severe environment problems such as resource depletion and global warming with massive carbon dioxide during its production. The number of cases using industrial by-products such as the ground granulated blast furnace slag (GGBFS) in concrete mixtures is increasing to resolve the environmental issue. GGBFS is mainly used in the range between 20 to 50% to replace cement, but nowadays lots of researches are carried out to develop the alkali-activated slag (AAS) concrete with no cement. In this study, the early age properties of alkali activated slag (AAS) mortar are investigated to obtain the fundamental data for AAS concrete application to structural members. The experimental variables were the water-binder ratios of 0.3, 0.4, and 0.5 and NaOH as the alkali activator of 4%, 8%, and 12% by the mass of GGBFS, and compressive strength, flow, setting time, and ultrasonic pulse velocity of AAS mortars were measured and analyzed. It is found from the test results that as the normal concrete the lower W/B, the higher compressive strength. However, superplasticizer has to be used for producing high strength AAS concrete because the workability of AAS mortar are significantly lowered.

• Korean Journal of Ecology and Environment
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• v.50 no.4
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• pp.432-440
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• 2017

Compound specific isotope analysis of amino acids (CSIA-AAs) is being highlighted as an alternative approach for overcoming some restrictions in application of stable isotope analysis of bulk tissue (SIA) for trophic position (TP) estimation. However, this approach has rarely been applied in Korea. The present study determines TP of two Polychaeta (Nephtyidae and Glyceridae) and two fish species(Platycephalus indicus and Lophius litulon) collected from the Geum River estuary using nitrogen isotope ratio of amino acid and compared with the TP values estimated by SIA. The Polychaeta species, sampled in two sites, showed similar TP between SIA(2.7 and 3.1) and CSIA-AAs (2.6 and 3.1). However, for both fish species, TP values displayed a large difference between SIA (3.1 and 2.3) and CSIA-AAs (3.8 and 3.7). In this study TP values estimated by CSIA-AAs showed more similar to the previously reported gut content analysis of both fishes compared with the results of SIA. Current study suggests the applicability of nitrogen isotope ratio of amino acid to understand coastal ecosystem structure and trophic ecology.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.315-322
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• 2012

Alkali-activated slag (AAS) is the most obvious alternative materials that can replace OPC. But, AAS industrial usage as a structural material should be evaluated for its durability. Carbonation resistance is one of the most important factors in durability evaluation. Test results for 18 slag-based mortars activated by sodium silicate and 6 OPC mortars were obtained in this study to verify the carbonation property. Main variables considered in the study were flow, compressive strength before and after carbonation, and carbonation depth. Mineralogical and micro-structural analysis of OPC and AAS specimens prior to and after carbonation was conducted using XRD, TGA, FTIR FE-SEM. Test results showed that CHS was major hydration products of AAS and, unlike OPC, no other hydration products were found. After carbonation, CSH of hydration product in AAS turned into an amorphous silica gel, and alumina compounds was not detected. From the analysis of the results, it was estimated that the micro-structures of CSH in AAS easily collapsed during carbonation. Also, the results showed that this collapse of chemical chain of CSH lowered the compressive strength of concrete after carbonation. By increasing the dosage of activators, carbonation resistance and compressive strength were effectively improved.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.6
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• pp.305-311
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• 2012

In order to recycle the coal bottom ashes (denoted as BA) produced from a thermal power plant, the artificial aggregates (denoted as AAs) containing BA and red clay were manufactured, and the physical properties of AAs were studied as a function of particle size of BA and batch compositions. As-received BA had 38 wt% coarse particles of above 2 mm and many unburned carbon mass and porous slag particles were co-existed. So the two particle sizes of BA, the fine (< 100 ${\mu}m$) and coarse (< 2 mm), were prepared by milling and screening process. The AAs containing fine BA sintered at $1100{\sim}1200^{\circ}C$ had the higher bulk density and lower water absorption compared to the specimen made of coarse BA. The inside core of AAs manufactured by using coarse BA showed nonuniform and porous microstructure, while the AAs made of fine BA had a uniform and dense microstructure. In this research, the AAs containing BA and red clay with various bulk density (1.2~1.7) and water absorption (13~21 %) could be manufactured by controlling the particle size of BA and batch compositions, so the AAs of various physical properties could be applied to the wide fields such as construction/building materials in near future.

• Reproductive and Developmental Biology
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• v.36 no.3
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• pp.193-198
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• 2012

This study was to examine expression of the recombinant full-length adiponectin (recombinant adiponectin) in insect ovarian cell culture system and to characterize structural properties of the recombinant adiponectin secreted in medium. Gene construct encoding the recombinant adiponectin contained N-terminal collagen-like domain (110 Amino Acids, AAs), C-terminal globular domain (137 AAs) and C-terminal peptides for detection with V5 antibody (26 AAs included adaptor peptide) and purification using the 6xHis tag (6 AAs). The approximate molecular weight of the product (monomer) was 35 kDa. Molecular mass species of the expressed recombinant adiponectin were monomer (~35 kDa), dimer (~70 kDa), trimer (~105 kDa) and hexamer (~210 kDa). The major secreted species were the LMW forms, such as monomer, dimer, and trimer. There was MMW of hexamer as minor form. HMW multimers (~300 kDa) were shown as a tracer or not detected on the SDS-PAGE in several experiments (data not shown). The multimer forms in this study were not compatible to those in animal or human serum and adipose tissue by other researcher's study in which the major multimer forms were HMW. By protein denaturing experiments with reducing reagent (${\beta}$-MeOH), anionic detergent (SDS) and heat ($95^{\circ}C$) on the SDS-PAGE, not all adiponectin multimers seemed to have disulfide bond linked structure to form multimers. The recombinant adiponectin which expressed in insect ovarian cell culture system seemed to have the limitation as full physiological regulator for the application to animal and human study.