• Bulletin of the Korean Chemical Society
• /
• v.31 no.5
• /
• pp.1143-1148
• /
• 2010

We investigated the separation of nitrogen heterocyclic compound (NHC) contained in a model coal tar fraction comprising four kinds of NHC [indole (In), quinoline (Q), iso-quinoline (iQ), quinaldine (Qu)], three kinds of bicyclic aromatic compound (BAC) [1-methylnaphthalene (1MN), 2-methylnaphthalene (2MN), dimethylnaphthalene (DMN) mixture with ten structural isomers (DMNs; regarded as one component)], biphenyl (Bp) and phenyl ether (Pe) by liquid membrane permeation (LMP). A batch-stirred tank was used as the permeation unit. An aqueous solution of saponin and n-hexane were used as the liquid membrane and the outer oil phase, respectively. Yield and selectivity of individual NHC was much larger than that of BAC, Bp and Pe. Increasing the initial mass fraction of the saponin to the membrane solution ($C_{sap,0}$) and the initial volume fraction of O/W emulsion to total liquid in a stirred tank (${\phi}_{OW,0}$) resulted in deteriorating the yield of individual NHC, but increasing the stirring speed (N) resulted in improving the yield of each NHC. With increasing $C_{sap,0}$, the selectivity of each NHC based on DMNs increased. Increasing ${\phi}_{OW,0}$ and N resulted in decreasing the selectivity of individual NHC based on DMNs. At an experimental condition fixed, the sequence of the yield and selectivity in reference to DMNs for each NHC was Q > Qu = iQ > In. Furthermore, we compared LPM method with methanol extraction method in view of the separation efficiency (yield, selectivity) of NHC.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.26 no.1
• /
• pp.48-57
• /
• 2016

Objectives: This study was conducted to evaluate the accuracy and precision of airborne metal analysis using polyvinyl chloride(PVC) membrane filter by pretreatment methods. Methods: A total of 75 spiked PVC samples for Cr, Fe and Mn ranged from 6 ug/sample to 40 ug/sample were used to evaluate recovery rates for three pretreatment methods: acid extraction, hot plate ashing and microwave digestion. For Mn, an additional 75 spiked mixed cellulose ester(MCE) membrane filters were analysed to compare the recovery rates of PVC samples. All samples were analysed with an inductively coupled plasma optical emission spectrometer(ICP-OES) and manganese samples were additionally analyzed by atomic absorption spectrometer(AAS). Results: The overall mean recovery rates of PVC samples for Cr, Fe and Mn were 90% or higher regardless of pretreatment methods, but there were statistically significant differences in recovery rates for Cr(p<0.05) and Mn(p<0.01) samples by pretreatment methods. The biases and the coefficient variations of PVC samples for three metals pretreated with three kinds of pretreatment methods ranged from 1.7% to 4.7% and from 1.6% to 6.5%, respectively. The manganese PVC samples pretreated by microwave digestion and analyzed with ICP-OES had the lowest bias at 1.9% and also showed lower bias than the bias for MCE samples, 2.7%. Conclusions: In order to accurately analyze the metals sampled with PVC membrane filters, microwave digestion and ICP-OES can be recommended.

• Korean Journal of Microbiology
• /
• v.26 no.3
• /
• pp.197-206
• /
• 1988

An outer membrane-associated 2-furaldehyde dehydrogenase, catalyzing the oxidation of 2-furaldehyde to 2-furoic acid from Klebsiella pneumoniae was purified to homogeneity and characterized. The enzyme showed its highly specific dependency on $\beta$-$NAD^{+}$. Enzyme activity was monitored during purification by using substrate 2-furaldehyde and coenzyme $\beta$-$NAD^{+}$ by means of high performance liquid chromatography. The outer membrane was successfully collected by the methods of Percoll density gradient ultracentrifugation and ultracentrifugation after preferential solubilization of the membrane with $Mg^{2+}$ and Triton X-100. The enzyme was purified by the series of procedures including extraction of outer membrane protein with EDTA and lysozume, and fractionation by column chromatography on QAE-Sephades Q-50, and subsequently Sephadex G-100. The enzume showed its optimal activity at $85^{\circ}C$, pH 9.5, and in the presence of 1.5% (vol/vol) Triton X-100. The enzyme exhibited a native molecular size of 88,000 by nondenaturing polyacrylamide gel electrophoresis and had an apparent Km of 4.72mM for 2-furaldehyde.

• Journal of Periodontal and Implant Science
• /
• v.37 no.3
• /
• pp.647-653
• /
• 2007

Rapid crestal bone resorption following maxillary tooth loss is further accentuated in the posterior regions because of pneumatization and enlargement of the maxillary sinuses. A treatment rationale that allows preservation and augmentation of vertical available bone at the time of posterior maxil-lary tooth extraction may offer numerous therapeutic benefits which are more short courses of ther-apy and no needs of additional surgical augmentation. The present study comprised 3 patients who had 4 posterior maxillary teeth with no evident bone between the tooth apex and sinus floor, as estimated through preoperative radiographic analysis. Sinus floor augmentation at the time of tooth extraction was chosen for the ltreatment of these patients. After the tooth was carefully extracted, the empty alveolus was thoroughly debrided and a trephine approach was performed. Particulated autogenous bone was gently pushed beyond the empty alveolus to elevate the sinus membrane using an osteotome. The distance between bone crest and si-nus floor was radiographically estimated 4 months after the first procedure. Another procedure was then carried out to place the implants of 11 mm length without another augmentation procedure. All implant were clinically stable, with no sign of infection. The presented surgical procedure performed at the time of extraction of posterior maxillary teeth in close proximity to the sinus floor allowed placement of implants of proper length.

• The Journal of the Korean dental association
• /
• v.58 no.6
• /
• pp.336-345
• /
• 2020

Peri-apical implant lesion, also known as 'retrograde peri-implantitis' can occur with multifactorial etiological factors. The purpose of this case report is to demonstrate resolution of periapical implant lesion by removal of causative factors and saving implant by regenerative therapy. A 54-year old male patient with mild dull pain around implant on the right mandibular second premolar area due to persistent peri-apical infection of the adjacent first premolar was treated. Extraction of tooth with symptomatic apical periodontitis and regenerative therapy on the buccal fenestration area of the implant and extraction site were performed. After 6-month reentry, notable regenerated bone tissue around implant was found, and implant placement on the previous extraction site was performed. After 14-month follow-up from the regenerative therapy, neither biological nor mechanical complication could be found around the implant, evidenced by high implant stability, normal clinical probing depth, and absence of discomfort spontaneously and during masticatory function. In conclusion, surgical intervention including regenerative therapy using bone graft and barrier membrane on periapical implant lesion can be suggested as one of the treatment options considering the extent of periapical lesion.

• Nuclear Engineering and Technology
• /
• v.52 no.2
• /
• pp.328-336
• /
• 2020

Cesium is a major product of uranium fission, which is the most commonly existed radionuclide in radioactive wastes. Various technologies have been applied to separate radioactive cesium from radioactive wastes, such as chemical precipitation, solvent extraction, membrane separation and adsorption. Crown ethers and calixarenes derivatives can selectively coordinate with cesium ions by ion-dipole interaction or cation-π interaction, which are promising extractants for cesium ions due to their promising coordinating structure. This review systematically summarized and analyzed the recent advances in the crown ethers and calixarenes derivatives for cesium separation, especially focusing on the adsorbents based on extractants for cesium removal from aqueous solution, such as the grafting coordinating groups (e.g. crown ether and calixarenes) and coordinating polymers (e.g. MOFs) due to their unique coordination ability and selectivity for cesium ions. These adsorbents combined the advantages of extraction and adsorption methods and showed high adsorption capacity for cesium ions, which are promising for cesium separation The key restraints for cesium separation, as well as the newest progress of the adsorbents for cesium separation were also discussed. Finally, some concluding remarks and suggestions for future researches were proposed.

• Journal of Korean Dental Science
• /
• v.14 no.1
• /
• pp.1-11
• /
• 2021

Purpose: The alveolar ridge preservation (ARP) is widely conducted for implant placement. However, experimental results using deproteinized porcine bone mineral (DPBM) have been scarce. This retrospective study evaluated factors affecting the primary stability of implants in an area where ARP was performed using DPBM. Materials and Methods: Thirty-eight patients were divided into two groups based on the primary stability, with torque value of 30 Ncm as borderline. To determine the factors that affect the primary stability of implants, we collected data from patients' medical records including age, sex, reentry time, socket location, remaining bone wall at the time of extraction, and type of collagen membrane, as well as from radiographs and histomorphometric analysis. Result: The results showed statistically significant difference for the remaining extraction socket wall (P=0.014), residual graft (P=0.029), and fibrovascular tissue (P=0.02) between the two groups. There was an insignificant tendency toward the time of reentry surgery (P=0.052) and location (P=0.077). All implants placed in sites using DPBM functioned well up to 3 years. Conclusion: Within the limitations of the present study, extraction socket wall, residual graft, and fibrovascular tissue can affect the primary stability at the time of implant placement on grafted sites using DPBM and collagen membranes. In addition, reentry time and locations can be considered. In future studies, comparative experiments in quantified models will be required to supporting the findings.

• Journal of Korean Society on Water Environment
• /
• v.32 no.6
• /
• pp.600-627
• /
• 2016

Korea is one of the countries with a large veterinary antibiotics market, although antimicrobial resistance in bacteria is becoming a serious issue in many countries. The Korean government started to take interest in estimating the effects of livestock manure on rivers and agricultural soils and in monitoring of heavy metals, organic pollutants and antibiotics in the ambient water and soil. In this paper, pre-treatment methods to separate the selected antibiotics from solid samples were reviewed. It is essential to select an efficient and appropriate procedure for pre-treatment due to the high proportion of proteins and organics in biosolid samples. Pre-treatment consists of extraction followed by clean-up. Initially, homogenized samples were extracted by sonication, mechanical agitation or pressurized liquid extraction with methanol/acetonitrile/water mixture under acidic/basic conditions depending on the compound. However, aminoglycosides and colistin were extracted with 5% trichloroacetic acid and HCl, respectively. Since the ${\beta}-lactams$ are easily decomposed in acidic and basic conditions, they were extracted in neutral pH. Filtration with a membrane (pore size, $0.2{\mu}m$) or solid phase extraction with HLB and methanol, as eluents, was normally applied for the clean-up. At least, three different pre-treatment procedures should be adopted to screen all the selected antibiotics in solid samples.

• Journal of Veterinary Clinics
• /
• v.24 no.3
• /
• pp.305-307
• /
• 2007

Lactoferrin-binding proteins (LBP) has not been well characterized in Streptococcus uberis isolated from milk of bovine mastitis and to date this protein is considered to be an important virulence factor in Streptococcal mastitis. To determine the more efficient extraction method of LBP from four S. uberis strains, we used two different extraction methods (mutanolysin and sodium dodecyl sulfate) in this study. Bacterial proteins extracted were electrophoresed by 10% polyacrylamide gels in the presence of sodium deodecyl sulfate and gels were transferred onto nitrocellulose membrane. Rabbit anti-bovine lactoferrin antibody and HRP-conjugated donkey anti-rabbit IgG antibody were used to detect LBP. This Western blotting analysis demonstrates that extraction method with SDS extracted 110 kDa and 112 kDa LBPs more efficiently compared to the mutanolysin extraction method.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.12
• /
• pp.1256-1260
• /
• 1997

A series of acyclic polyethers bearing amide end-groups and lipophilic alkyl chains (3-5) were successfully synthesized with quantitative yields. Based upon the transport experiment in a bulk liquid membrane (BLM) system and solvent extraction, a very high selectivity of Pb2+ over other transition metal cations was observed. Measurement of thermodynamic parameters for complexation in methanol at 25 ℃ gave a strong evidence for excellent selective complexation for lead ion over other transition metal ions.