• Resources Recycling
• /
• v.18 no.6
• /
• pp.30-37
• /
• 2009

Silica sol was prepared from the mixture of sodium silicate solution and oxidized silicate solution in which sodium had been removed by sol-gel process. The properties of sodium silicate solution and silicate solution thus prepared were characterized by yellow silicomolydate method. Moreover, the formation and growth of silica sol from sodium silicate solution was investigated. Sodium silicate solution with 2% of $SiO_2$ contains 95% of reactive silicate, and 50% of reactive silicate participates sol-gel reaction. From the results of FT-IR analysis, it was found that the intensity of silanol bond decreased and the intensity of siloxane bond increased with increasing reaction temperature. Zeta potential of silica sol prepared at each condition was -40~-60 mV and it could be known that silica sol in this study was well dispersed. The silica sol with 5~10 nm size could be prepared by heating the mixed solution of sodium silicate and silicate solution. And the silica sol grew into about 20 nm as silicate solution was added to silica sol solution.

• Korean Journal of Environmental Agriculture
• /
• v.16 no.4
• /
• pp.333-340
• /
• 1997

An analytical method was developed to determine residues of haloxyfop-R and its methyl ester in soils and soybeans using gas-liquid chromatography (GLC) with electron capture detector (ECD). Soil or soybean sample was acidified and extracted with acetone. The extract was then subjected to ion-associated partition to individually separate haloxyfop-R and the neutral methyl ester. One phase containing haloxyfop-R was methylated with $BF_3$/methanol, partitioned to n-hexane and analyzed by GLC/ECD. The other phase containing the methyl ester was further purified by Florisil column chromatography prior to GLC determination. No cross contamination was found between two phases containing each of the acid and methyl ester, thus two compounds can be separately determined as the identical haloxyfop-R-methyl. Overall recoveries of haloxyfop-R from fortified samples averaged 88.2${\pm}$3.9% (n=12) and 88.3${\pm}$4.0% (n=6) for soils and soybeans respectively, and those of haloxyfop-R-methyl showed mean values of 89.2${\pm}$4.0% (n=12) and 85.6${\pm}$5.6% (n=6). Detection limits of both haloxyfop-R and its methyl esterwere 0.005㎎/㎏ and 0.01㎎/㎏ for soil and soybean samples respectively.

• Korean Journal of Soil Science and Fertilizer
• /
• v.33 no.1
• /
• pp.40-46
• /
• 2000

The investigation and the analysis of soil chemical properties, microbial flora and cultural practices in plastic house of 60 farms (pepper 20, cucumber 20, oriental melon 20) were conducted in Chonnam area film. An amount of fertilizer application of farms was more than that of standard fertilizer application. That was phosphate at two and a half times, potassium at twice and manure at three times the amount of standard application. It was inferred that excessive fertilizer application would lead to salts accumulation in soil. Continuous cropping injury would be incurred by excesive salts accumulation in soil. Even if inorganic elements in soil culturing peppers, cucumbers and oriental melons were greater than optimum level, base-saturation degree of soil culturing peppers, cucumbers and oriental melons was 40:18:12, 55:16:14 and 40:27:11 respectively. That was lower than the optimum levels (60:15:5). Therefore, crops would be affected by uptake inhibition by nutrition imbalance. Density of Fusarium is related to plant decease in soil i.e. pepper $26.2{\times}10^2\;cfu\;g^{-1}$, cucumber $75.8{\times}10^2\;cfu\;g^{-1}$ and oriental melon $6.5{\times}10^2\;cfu\;g^{-1}$. B/F of soil planted with pepper, cucumber and oriental melon was 91.2, 80.4 and 18.8, respectively.

• Food Science and Preservation
• /
• v.12 no.4
• /
• pp.402-410
• /
• 2005

In order to manufacture the alcoholic drinks using cultured wild ginseng roots(CWGR) of 5 and $10\%$ (w/v), sugar content of fermentation media was adjusted to 24-25 $^{\circ}$Brix with white sugar and glucose. And 3 kinds of yeast (S. cerevisiae(KCCM 50757), S. cerevisiae (KCCM 50583) and S. bayanus(ATCC 10601) were used and then the quality of alcoholic drinks was analyzed by physical, chemical and sensory evaluation. Alcohol content was highest value of $15.8\%$ in $10\%$ of CWGR, white sugar, and S. bayanus(ATCC 10601). Major alcohols were ethanol and 1-propanol. Number of yeast cells increased to 5 days fermentation and slightly decreased afterwards. The pH was decreased abruptly from 5.0 in initial fermentation to 3.1-4.1 in 5 days fermentation. Total sugar contents were decreased continuously with fermentation periods and showed 7.0-10.5 $^{\circ}$Brix in 20 days fermentation. Saponin patterns and contents were various and higher in wine treated with S. bayanus(ATCC 10601). From the sensory evaluation, the highest score of overall quality was observed in the alcoholic beverage of $10\%$(w/v) of CWGR, glucose, and S. cerevisiae(KCCM 50583).

• Applied Chemistry for Engineering
• /
• v.32 no.6
• /
• pp.684-689
• /
• 2021

In this paper, we develop a cost effective and disposable voltammetric sensing platform involving screen-printed carbon electrode (SPCE) modified with the nanocomposites composed of multi-walled carbon nanotubes, polyelectrolyte, and tyrosinase for bisphenol A. This is known as an endocrine disruptor which is also related to chronic diseases such as obesity, diabetes, cardiovascular and female reproductive diseases, precocious puberty, and infertility. A negatively charged oxidized multi-walled carbon nanotubes (MWCNTs) wrapped with a positively charged polyelectrolyte, e.g., polydiallyldimethylammonium, was first wrapped with a negatively charged tyrosinae layer via electrostatic interaction and assembled onto oxygen plasma treated SPCE. The nanocomposite modified SPCE was then immersed into different concentrations of bisphenol A for a given time where the tyrosinase reacted with OH group in the bisphenol A to produce the product, 4,4'-isopropylidenebis(1,2-benzoquinone). Cyclic and differential pulse voltammetries at the potential of -0.08 V vs. Ag/AgCl was employed and peak current changes responsible to the reduction of 4,4'-isopropylidenebis(1,2-benzoquinone) were measured which linearly increased with respect to the bisphenol A concentration. In addition, the SPCE based sensor showed excellent selectivity toward an interferent agent, bisphenol S, which has a very similar structure. Finally, the sensor was applied to the analysis of bisphenol A present in an environmental sample solution prepared in our laboratory.

• The Korea Journal of Herbology
• /
• v.33 no.5
• /
• pp.105-110
• /
• 2018

Objectives : We tried to observe the fluorescence anisotropy and intensity of ethidium ion in the intercalating binding interaction between DNA and ethidium ions in the presence of berberine, and then tried to explain the effect of berberine on the intercalating interaction of ethidium ion with DNA. Methods : DNA(calf thymus DNA), berberine and ethidium bromide(EtBr) were purchased from Sigma-Aldrich Co. Proper amount of each compound was dissolved in 20 mM sodium phosphate buffer(pH 7.0) containing 100 mM of NaCl to prepare stock solutions. Collections of the fluorescence anisotropy and intensity data were performed on JASCO FP-8300 spectrofluorometer equipped with a polarizer and a Peltier temperature controller. The excitation of ethidium ion was done at 550 nm and the emission data were collected at 600 nm. For Stern-Volmer plot, the fluorescence data were collected at $18^{\circ}C$ and $30^{\circ}C$. Results : According to the results of this research, the weak competitive binding pattern between ethidium ion and berberine appeared in binding with DNA at low ratio of DNA to ethidium ion. But at high ratio of DNA to ethidium ion, this weak competition disappeared. Instead, berberine might bind to DNA by intercalating way. In other words, berberine could de-intercalate ethidium ion from DNA at low concentration of DNA relative to ethidium ion, but could not at high concentration of DNA relative to ethidium ion. In addition, the mechanism of fluorescence quenching of ethidium ion could also proceed differently, depending on the ratio of the amount of DNA to that of ethidium ion. Conclusions : The effect of berberine on the DNA-ethidium ion intercalating interaction could work differently, depending on the relative ratio of the amount of DNA to that of ethidium ion. This study also showed that fluorescence anisotropy analysis is very useful method to obtain detailed information for investigation of the complex binding interactions. In order to fully understand the mechanism of action of the pharmacological effect by berberine, studies on the effect of berberine on the action of proteins such as various enzymes closely related to berberine-induced medicinal effects should be continued.

• The Korea Journal of Herbology
• /
• v.34 no.6
• /
• pp.79-89
• /
• 2019

Objective : This study investigated the anti-diabetic effects of DM1, a herbal mixture with Atractylodis Rhizoma, Anemarrhenae Rhizoma, and Cinnamomi Cortex in high fat diet (HFD)-induced diabetic mice and the mechanism in C2C12 mouse skeletal muscle cells. Methods : The C57B/6 mice were fed high fat for 12 weeks, and then administrated DM1 extract (500 mg/kg, p.o.) for 4 weeks. The changes of body weight, calorie and water intakes, fasting blood glucose levels and the serum levels of glucose, insulin, triglyceride, HDL-cholesterol, AST and ALT were measured in mice. The histological changes of liver and pancreas tissues were also observed by H&E stain. C2C12 myoblasts were differentiated into myotubes and then treated with DM1 extract (0.5, 1, and 2 mg/㎖) for 24 hr. The expression of myosin heavy chain (MHC), PGC1α, Sirt1 and NRF1, and the AMPK phosphorylation were determined in the myotubes by western blot, respectively. Results : The DM1 extract administration significantly decreased the calorie and water intakes, glucose, triglyceride, AST and ALT levels and increased insulin and HDL-cholesterol in HFD-induced diabetic mice. DM1 extract inhibited lipid accumulation in liver tissue and improved glucose tolerance. In C2C12 myotubes, DM1 treatment increased the expression of MHC, PGC1α, Sirt-1, NRF-1 and the AMPK phosphorylation. Conclusion : In our results indicate that DM1 can improve diabetic symptoms by decreasing the obesity, glucose tolerance and fatty liver in HFD-induced diabetic mice, and responsible mechanism is might be related with energy enhancement.

• Resources Recycling
• /
• v.32 no.3
• /
• pp.9-17
• /
• 2023

Efforts are currently underway to develop a method for efficiently recovering lithium from the cathode material of waste lithium iron phosphate batteries (LFP). The successful application of lithium battery recycling can address the regional ubiquity and price volatility of lithium resources, while also mitigating the environmental impact associated with both waste battery material and lithium production processes. The isomorphic substitution leaching process was used to recover lithium from spent lithium iron phosphate batteries. Lithium was leached by the isomorphic substitution of Fe²⁺ in LFP using a relatively inexpensive ferric chloride etching solution as a leaching agent. In the study, the leaching rate of lithium was compared using the ferric chloride etching solution at various multiples of the LFP molar ratio: 0.7, 1.0, 1.3, and 1.6 times. The highest lithium leaching rate was shown at about 98% when using 1.3 times the LFP molar ratio. Subsequently, to eliminate Fe, the leachate was treated with NaOH. The Fe-free solution was then used to synthesize lithium carbonate, and the harvested powder was characterized and validated. The surface shape and crystal phase were analyzed using SEM and XRD analysis, and impurities and purity were confirmed using ICP analysis.

• Korean Journal of Soil Science and Fertilizer
• /
• v.38 no.3
• /
• pp.150-156
• /
• 2005

The increasing emission of greenhouse gases may change agricultural environment. The agronomic productivity will depend upon change of temperature, precipitation, solar radiation and fertilization. This study was conducted to investigate greenhouse gas emission with irrigation water depth in paddy field. Area of each experiment plot is $70m^2$, Three treatments with three replications were carried out in this experiment, which was laid out as randomized complete block design. The treatments of irrigation water were maximum field water capacity and 4 and 8 cm depth. The application rate of fresh rice straw was $8,000kg\;ha^{-1}$ in combination with chemical fertilizers ($110kg\;N\;ha^{-1}$, $45kg\;P_2O_5\;ha^{-1}$ and $57kg\;K_2O\;ha^{-1}$). The $CH_4$ emission was highest at 32 days after rice transplanting with rice straw treatment. The $CH_4$ emission in the plot of maximum field water capacity was lower compared with 4 and 8 cm of irrigation depth. $CH_4$ and $N_2O$ emission under different water depth in the paddy field were 30 and $1.52kg\;ha^{-1}$ at 8 cm depth, 281 and $1.71kg\;ha^{-1}$ at 4 cm depth, and 219 and $2.01kg\;ha^{-1}$ at water saturated condition. The total emission of greenhouse gases equivalent to $CO_2$ emission with rice straw application were $6,939kg\;CO_2\;ha^{-1}$ at 8 cm depth plot, $6,431kg\;CO_2\;ha^{-1}$ at 4 cm depth plot and $5,222kg\;CO_2\;ha^{-1}$ at water saturated condition. The GWPs without rice straw application were $4,449kg\;CO_2\;ha^{-1}$ at 8 cm depth plot, $3,702kg\;CO_2\;ha^{-1}$ at 4 cm depth plot and $4,579kg\;CO_2\;ha^{-1}$ at water saturated condition.

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1996.06b
• /
• pp.219-222
• /
• 1996

수열법은 밀폐용기중에서 10$0^{\circ}C$이상의 가열, 가압된 수용액이 반응에 관여하는 것으로써, 수정, CaCO3, AlPO4, GaPO4 등과 같은 단결정의 육성 뿐만 아니라 균일분산계로부터 균일한 결정성의 미립자 합성에도 폭넓게 이용되고 있다. 세라믹분말의 합성에 있어서, 이 방법은 특히 형상, 입자크기의 제어가 용이할 뿐만 아니라 고상법, 졸-겔법, 공침법에서와 같은 열처리, 분쇄과정이 필요없기 때문에 고순도의 초미립자를 얻을 수 있는 장점이 있다. 근년 미국, 일본에서는 수열법을 이용한 유전, 압전체 등 세라믹분말의 일부가 공업적인 규모로 대량 생산되고 있다. 그러나 이에 대한 국내 기술은 아직 초기단계에 이르고 있는 실정이다. 따라서 본 연구실에서는 수열법에 의한 단결정 육성 (예; 자수정, CaCO3, AlPO4, GaPO4, KTP, Emerald 등), 박막제조 (예; GaP, PbTiO3, BaTiO3 등), 정제 (고령토, 장석, 도석 등), 원석처리 (진주, 인공 emerald, 비취 등) 그리고 각종 세라믹분말의 합성 등과 같은 다양한 기반기술의 축적과 동시에 공업화에 대응한 수열장치를 위하여 반응용기의 대형화, 엄밀한 밀폐방식, 실용적인 수열조건 등을 개발해 오고 있다. 본 발표에서는 현재까지의 연구개발 내용 중에서 결정성 미립자에 관련한 세라믹분말의 합성에 대한 일부의 결과들을 보고한다. 일반적으로 수열장치는 전기로, 반응용기, 온도 및 압력제어계 등을 기본으로 하고 있으며 시판용의 대부분이 교반기가 부착된 수직형 (vertical type)이다. 이와 같은 방식에 있어서는 엄밀한 밀폐가 곤란, 반응온도의 한계성 (25$0^{\circ}C$ 이하), 증진율의 한계성 (소량생산) 등과 같은 점이 있기 때문에 본 연구실에서는 개폐식 전기로내에 엄밀한 밀폐가 가능한 수평식(horizontal type)의 반응용기를 채택한 뒤 이를 회전 또는 시이소(seesaw)식으로 움직일 수 있도록 하여 연속공정화, 온도구배의 자율조절 그리고 보다 저온에서도 인위적인 이온의 확산을 효율적으로 유도할 수 있도록 하였다. 이와 같은 방식은 기존의 방식과 비교하여 반응용기 내에 응집현상과 미반응물이 존재하지 않으며 또한 단분산으로 결정성 미립자를 대량적으로 얻을 수 있는 장점이 있었다. 다음은 이상과 같이 본 연구실에서 자체 개발한 수열장치를 이용하여 PbTiO3, (Pb,La)TiO3Mn, BaTiO3, ZnSiO4:Mn, CaWO4 등과 같은 세라믹분말에 대한 합성 실험의 결과이다. 압전성, 초전성이 우수한 PbTiO3 및 (Pb,La)TiO3:Mn 분말의 수열합성은 PbO, TiO2, La2O3 등의 분말을 출발원료로 하여 합성도도 25$0^{\circ}C$부근의 알카리성 용액중에서 결정성 PbTiO3 및 (Pb,La)TiO3:Mn 미립자를 단상으로 얻었으며 입자의 형상 및 크기는 합성온도와 수열용매의 종류에 의존하였다. 유전체로서 폭넓게 응용되고 있는 BaTiO3 분말은 Ba(OH)2.8H2O, TiO2와 같은 최적의 출발원료를 선택함으로써 15$0^{\circ}C$ 부근의 저온영역에서도 용이하게 합성할 수 있었다. 특히 본 연구에서는 수용성인 Ba(OH)2.8H2O를 사용함으로써 host-guest적인 반응을 유도시키는데 있어 물의 가장 실용적이고 효과적인 수열용매임도 알았다. ZnSiO4:Mn, CaWO4, MgWO4와 같은 형광체 분말은 공업적으로 고상반응 또는 습식법에 의해 얻어지고 있으나 이들 방법에 있어서는 분쇄공정으로 인한 형광특성의 저하와 같은 문제점이 있다. 따라서 본 연구에서는 수열법을 이용하여 이들 화합물의 합성을 시도하였으며 그 결과 합성온도 30$0^{\circ}C$ 부근의 알칼리성 용액중에서 수열적으로 얻어짐을 알았다. 여기서의 합성분말을 이용하여 실제 조명램프로 제조한 결과 녹색, 청색 발광용 형광체로서 우수한 형광특성을 나타내었다. 천연에서 소량 산출되고 있는 고가의 (Li,Al)MnO2(OH)2:Co 분말은 도자기의 전사지용 청색안료로써 이용되고 있다. 본 연구실에서는 LiOH.H2O, Al(OH)3, MnO2 등의 분말을 출발원료로 하고 24$0^{\circ}C$ 온도 부근 그리고 물을 수열용매로 하여 천연산에 필적하는 (Li,Al)MnO2(OH)2:Co 분말을 인공적으로 합성하였다.