• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.561-569
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• 2014

This study was carried out to get the characteristics of anaerobic digestion for chemical/biological sludge produced from municipal sewage treatment plant for phosphorus. Anaerobic mesophilic batch tests showed that the ultimate biodegradability of waste activated sludge showed 31%, PACl sludge 24%, Alum sludge 26%, respectively. At the S/I 1.0, 75% of total biodegradable volatile solids (TBVS) of waste activated sludge was degraded with an initial rapid decay coefficient, k1 of $0.1129day^{-1}$ and 74% of TBVS of PACl sludge with k1 of $0.0998day^{-1}$, and 76% of TBVS of Alum sludge with k1 of $0.1091day^{-1}$ for 20 days. During the operation of SCFMRs, the 3 reactor (Control, PACl, Alum) pH maintained 6.7~7.0 and the reactor alkalinity maintained 1,800~ 2,200 mg/L as $CaCO_3$. The average biogas production rates of SCFMRs fed with PACl sludge and Alum sludge were 0.089 v/v-d and 0.091 v/v-d, respectively, which was 27~28% lower than that of the control (0.124 v/v-d) at an HRT (hydraulic retention times) of 20 days. And the methane content during the operation ranged 70~76% in 3 reactor. The average TVS removal efficiency of SCFMRs fed with PACl sludge and Alum sludge were 19.6% and 19.9%, respectively, at an HRT of 20 days, which showed 4% lower than that of the control (23.8%). The average BVS removal efficiency of SCFMRs fed with PACl sludge and Alum sludge were 25.8% and 26.9%, respectively, at an HRT of 20 days, which was 8~9% lower than that of the control (34.5%).

• Membrane Journal
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• v.22 no.2
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• pp.95-103
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• 2012

To treat nitrate and non-biodegradable organics effectively in sewage, industrial wastewater and livestock wastewater, the activated sludge process integrated by a membrane separation and a porous electrode- electrolysis was proposed and its efficiency was investigated. The proposed system was consisted of 3 processes; activated sludge, membrane filtration and electrolysis. In the study, the membrane filtration played a role in reducing the load of the electrolysis to operate the proposed process stably. The electrolysis consisted of a porous electrode to increase the efficiency due to the extension of the specific surface area. Additionally, redox reaction in the electrolysis was induced by decomposing influent water as current was applied. As a result, hydrogen free radicals and oxygen radicals as intermediates were produced and they acted as oxidants to play a role in decomposing non-degradable organics. It was environmentally-friendly process because intermediates produced by porous electrode were used to treat waste matters without supplying external reagent. Experimental data showed that the proposed process was more excellent than activated sludge process. SS removal efficiencies of the proposed process, membrane filtration and activated sludge process were about 100%, about 100% and about 90%, respectively. COD removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 92%, about 84% and about 78%, respectively. T-N removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 88%, about 67%, and about 58%, respectively. The SS data showed that SS was efficiently removed in the single of the membrane filtration. The COD/T-N data showed that COD/T-N of membrane hybrid process was treated by removing a little soluble organics and SS, and that COD/T-N of electrolysis hybrid process was treated by oxidize organics with high removal rate.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.474-481
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• 2012

This study was performed to investigate the degree of long-term pollution at the mainstream of the Han River by comparing the concentration of BOD and COD from 1975 to 2011. The long-term annual average BOD and COD concentration at the mainstream of the Han River showed an increasing trend as it flowed downstream from Paldang Dam to Gayang. The concentration of BOD ($r^2$=0.646) and COD ($r^2$=0.260) showed a consistent decreasing trend for 37 years. In the case of Paldang Dam, BOD has maintained a decreasing trend, whereas the COD value showed an increasing trend after the 1990s. Therefore, a control of non-biodegradable materials in areas around Paldang Dam is required. The result of the seasonal variations of BOD and COD is as follows: spring>winter>summer and fall (p<0.001). The time series analysis revealed a strong correlation for every 12-month period. Also, the amount of water discharge at Paldang Dam has to be systematically controlled because the amount of water discharge from the dam influences the water quality at the mainstream of the Han River.

• Polymer(Korea)
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• v.24 no.4
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• pp.505-512
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• 2000

The mixture density data for poly(lactide-co-glycolide) [PLGA] with supercritical $CO_2$, CHF$_3$ and CHClF$_2$ were obtained in the temperature range of 27 to 10$0^{\circ}C$ and at pressures as high as 3000 bar (PLGA$_{x}$, Where the molar concentration of glycolide in the backbone, x, range from 0 to 50 mol%). The PLA-$CO_2$, PLA-CHF$_3$, and PLA-CHClF$_2$ systems dissolve in the pressure less than 1430 below 700, and below 100 bar, respectively. The mixture density shows from 1.084 to 1.334 g/cm$^3$ at temperatures from 27 to 93$^{\circ}C$. The PLGA$_{15}$ -$CO_2$ mixture dissolves at pressures of below 1900 bar and the mixture density is in the range of 1.158 to 1.247 g/cm$^3$ at temperatures between 37 and 92$^{\circ}C$. The solubilities of the PLGA$_{25}$ for $CO_2$, CHF$_3$, and CHClF$_2$ are shown to pressure as high as 2390, 1470, and 118 bar, respectively, and the mixture density exhibits iron 1.154 to 1.535 g/cm$^3$ at temperatures from 29 to 81$^{\circ}C$. The PLGA$_{50}$-$CO_2$ system does not dissolve at 24$0^{\circ}C$ and 3000 bar while the PLGA$_{50}$-CHCIF$_2$ does easily at 5$0^{\circ}C$ and 100 bar. The mixture density for the PLGA-CHClF$_2$ system increases even at low pressures as the glycolide molar concentration increases.es.es.

• Development and Reproduction
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• v.15 no.2
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• pp.87-98
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• 2011

The present experiment was performed to evaluate the osteogenic differentiation of human adipose tissue derived mesenchymal stem cells (ATMSCs) seeded in bioceramic-poly D,L-latic-co-glycolic acid (PLGA) scaffold. Osteogenic differentiation of ATMSCs were induced using the osteogenic induction (OI) medium. ATMSCs were cultured with OI medium during 28 days in well plate. The proliferation of ATMSCs in OI medium group was significantly increased for 14 days of plate culture but slowed after 21 days. On the other hand, proliferation in the control group showed constant increase for 28 days of culturing. The alkaline phosphatase (ALP) activity of ATMSCs in OI medium group increased during the 21 days of culture but decreased on 28 days. However, in control group ALP activity of ATMSCs was continuously decreased as time goes. Nodule was observed at 21 days of culture in OI medium group and confirmed accumulation of calcium in cell by alizarin red staining. ATMSCs were seeded in PLGA scaffold or in Bioceramic-PLGA scaffold, and cultured with OI medium. ALP activity of ATMSCs by osteoblast differentiation in each scaffold increased on 21 days of culture and decreased rapidly on 28 days. ALP activity of ATMSCs was increased highly in Bioceramic-PLGA scaffold compared to PLGA scaffold on 21 days of culturing. SEM-EDS analysis demonstrated that calcium and phosphate content and Ca/P ratio in Bioceramic-PLGA scaffold increased higher than in PLGA scaffold. Biodegradability of scaffold at 56 days after implantation showed that Bioceramic-PLGA scaffold was more biodegradable than PLGA scaffold. The results demonstrated that the differentiation of ATMSCs to osteoblast were more effective in scaffold culture than well plate culture. Bioceramic increased cell adhesion rate on scaffold and ALP activity by osteoblast differentiation. Also, bioceramic was considered to increase the calcium and phosphate in scaffold when ATMSCs was mineralized by osteogenic differentiation. Bioceramic-PLGA scaffold enhanced the osteogenesis of seeded ATMSCs compared to PLGA scaffold.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.2
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• pp.66-75
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• 2012

The objective of this study was to assess the effects of methanogenic bacteria-activated leachate recirculation method for enhancing waste stabilization and landfill gas production from a solid waste landfill. To simulate a conventional landfill (Lys-A), a landfill recirculated only fresh leachate (Lys-B), and two landfills recirculated leachate after pretreating with ASBR (Lys-C and Lys-D), four lysimeters were operated over a period of 4 years. Lys-D was recirculated two times of pretreated leachate volume than that of Lys-C. In the case of the landfill recirculated only fresh leachate and the landfill recirculated leachate after pretreating with ASBR, methane productions were increased until about 600 days, but there were not effect of leachate recirculation for enhancing methane production after about 600 days. It was assumed that leachate recirculation into fewer biodegradable organic wastes had not effect to enhance landfill gas production. Lys-C and Lys-D showed the highest performance for enhancing cumulative methane yield as well as acceleration waste stabilization. In cumulative methane yield, Lys-C (35.51 mL $CH_4/g$ VS) and Lys-D (36.12 mL $CH_4/g$ VS) were much higher than Lys-A (28.37 mL $CH_4/g$ VS) and Lys-B (30.07 mL $CH_4/g$ VS). In case of between Lys-B and Lys-C with the same recirculation rate, COD concentration in Lys-C was more rapidly decreased compared with that in Lys-B. This was attributed to the presence of methanogenic bacteria as well as dilution of inhibitory substances by the methanogenic bacteria-activated leachate recirculation. Therefore, the landfill recirculated leachate after pretreating with ASBR was found to be the most appropriate operating techniques for enhancing waste stabilization and landfill gas production.

• Journal of Periodontal and Implant Science
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• v.31 no.1
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• pp.1-23
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• 2001

Chitosan is biodegradable natural polymer that has been demonstrated its ability to improve wound healing, and calcium metaphosphate(CMP) is a unique class of phosphate minerals having a polymeric structure. In this study, chitosan/CMP and platelet derived growth factor(PDGF-BB) loaded chitosan/CMP sponges were developed, and the effect of the sponges on bone regeneration and their possibility as scaffolds for bone formation by three-dimensional osteoblast culture were examined. PDGF-BB loaded chitosan/CMP sponges were prepared by freeze-drying of a mixture of chitosan solution and CMP powder, and soaking in a PDGF-BB solution. Fabricated sponge retained its 3-dimensional porous structure with $100-200\;{\mu}m$ pores. The release kinetics of PDGF-BB loaded onto the sponge were measured in vitro with $^{125}I-labeled$ PDGF-BB. In order to examine their possibility as scaffolds for bone formation, fetal rat calvarial osteoblastic cells were isolated, cultured, and seeded into the sponges. The cell-sponge constructs were cultured for 28 days. Cell proliferation, alkaline phosphatase activity were measured at 1, 7, 14 and 28 days, and histologic examination was performed. In order to examine the effect on the healing of bone defect, the sponges were implanted into rat calvarial defects. Rats were sacrificed 2 and 4 weeks after implantation and histologic and histomorphometrical examination were performed. An effective therapeutic concentration of PDGF-BB following a high initial burst release was maintained throughout the examination period. PDGF-BB loaded chitosan/CMP sponges supported the proliferation of seeded osteoblastic cells as well as their differentiation as indicated by high alkaline phosphatase activities. Histologic findings indicated that seeded osteoblastic cells well attached to sponge matrices and proliferated in a multi-layer fashion. In the experiments of implantation in rat calvarial defects, histologic and histomorphometric examination revealed that chitosan/CMP sponge promoted osseous healing as compared to controls. PDGF-BB loaded chitosan/CMP sponge further echanced bone regeneration. These results suggested that PDGF-BB loaded chitosan/CMP sponge was a feasable scaffolding material to grow osteoblast in a three-dimentional structure for transplantation into a site for bone regeneration.

• Clinics in Shoulder and Elbow
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• v.15 no.1
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• pp.8-15
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• 2012

Purpose: The object of this study was to investigate the difference in torque and pullout strength between the standard anchor insertion (5.0 mm) with a small awl (3.7 mm) and larger anchor insertion (6.5 mm), with a standard awl (5.0 mm) in osteoporotic humeral head. Materials and Methods: The embalmed 24 paired cadaveric shoulders were assigned to either Group A or B. After measuring the bone mineral density (BMD) of the ROI (region of interest) in the humeral head, 5.0 mm suture anchors were inserted using a 3.7 mm awl in Group A1, and the same 5.0 mm anchors were inserted using a 5.0 mm awl in Group A2. The 5.0 mm anchors were inserted using a 5.0 mm awl in Group B1, and 6.5 mm anchors were inserted using a 5.0 mm awl in Group B2. We measured the torques at the time of the anchor insertion and pullout strengths. Results: There was no significant difference in the BMD between the groups. The torque of A1 (20.6 $cN{\cdot}m$) was significantly higher than that of A2 (13.2 $cN{\cdot}m$), and the torque of B2 (20.8 $cN{\cdot}m$) was significantly higher than that of B1(12.1 $cN{\cdot}m$). However, the difference in the increased torque between group A and B was not significant. The pullout strength of A1 (204.2 N) was significantly higher than that of A2 (152.9 N), and the pullout strength of B2 (210.9 N) was significantly higher than that of B1 (149.5 N). However, the difference in the increased pullout strength between Group A and B was not significant. Conclusion: In severe osteoporosis, the use of a larger suture anchor with a standard awl increased the torque and pullout strength significantly, in comparison to the use of the same sized suture anchor and awl. If there is an inadequate interval between the anchors on the greater tuberosity, the use of a 3.7 mm awl and 5.0 mm anchor will be beneficial compared to that of a 5.0 mm awl and 6.5 mm anchor, considering that an increase in the pullout strength does not depend on the awl size.

• Journal of Veterinary Clinics
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• v.29 no.4
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• pp.283-296
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• 2012

Allergic contact dermatitis (ACD) is an inflammatory skin disease and regarded as a prototype of T-cell mediated delayed-type hypersensitivity reactions. Poly-${\gamma}$-glutamic acid (PGA) is a biodegradable polymer that is produced by Bacillus subtilis. This study was performed to assess the effects of PGA in a canine model of ACD. ACD was induced on the back of dogs induced by sensitization and repeated application by 2,4-dinitro-1-chlorobenzene (DNCB). Topical treatment of PGA was applied once a day for 12 days and skin biophysical parameters including transepidermal water loss (TEWL), skin hydration, skin pH, skin thickness and erythema index, were measured every two days during experimental periods. Histopathology and immunohistochemistry were performed to evaluate the antiinflammatory effect. In skin biophysical parameters, TEWL, skin hydration, skin thickness and erythema index were significantly increased, with a maximum increase appeared on day 2 (p < 0.05). On the other hand, skin pH was significantly decreased, with a maximum decrease appeared on day 2 (p < 0.01). After the completion of PGA treatment, skin biophysical parameters were significantly reached those of baseline in a time-dependent manner (p < 0.05). In histopathology, marked increases of epidermal thicknesses were induced after DNCB challenge with numerous inflammatory cell infiltrations and edematous changes, decreases of connective tissue occupied regions in dermis. In addition, marked increases of cytokine - tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) and interferon-${\gamma}$ (IFN-${\gamma}$)-immunoreactivities in the dermis and of apoptotic markers - caspase-3 and PARP-immunoreactivities in the epidermis were observed in DNCB-PBS control as compared with intact control, respectively (p < 0.01). It means, the ACD and related apoptotic changes were induced by DNCB in the present study. However, these ACD induced by DNCB and related apoptosis in epidermis were significantly inhibited by treatment of PGA treated skin, the decreases of infiltrated inflammatory cells and related decreases of pro-inflammatory cytokine immunoreactivities were also observed (p < 0.01). Based on these findings, PGA may have anti-inflammatory and alleviatory effects in the allergic contact dermatitis.