• 한국결정성장학회지
• /
• 제22권3호
• /
• pp.147-151
• /
• 2012

이산화탄소($CO_2$)를 폐기물에 안정하게 고정화시키기 위하여 탄산화 가능한 알칼리 토금속인 Ca와 Mg 성분을 다량 포함한 석탄재에 CO2를 저장하여 건자재의 제조 가능성을 연구하였다. 초기 실험으로는 Ca 산화물과 수화물을 사용하였으며, $CO_2$ 저장 반응기로는 Autoclave를 사용하여 일정한 압력과 온도에서 조성을 변화시켜 탄산화를 시행하였다. 탄산화 된 시편의 무게변화율, X-선 회절분석 및 시차열분석을 통하여 관찰한 결과 $Ca^{2+}$의 이온용출 반응에 의해 탄산화가 진행되었음을 확인할 수 있었다. 10 $kgf/cm^2$의 압력과 $120^{\circ}C$에서 10분간 온도를 유지한 분위기에서 폐기물자원 원료에 15 % 이상의 탄산화율을 얻는 것이 가능할 것으로 판단되었다.

• 대한치과기공학회지
• /
• 제27권1호
• /
• pp.79-88
• /
• 2005

This study was performed to investigate the surface properties of electrochemically oxidized pure niobium by anodic oxide and hydrothermal treatment technique. Niobium specimens of $10\times10mm$ in dimension were polished sequentially from #600, #800, #1000 emery paper. The surface pure niobium specimens were anodized in an electrolytic solution that was dissolved calcium and phosphate in water. The electrolytic voltage was set in the range of 250 V and the current density was 10 $mA/cm^2$. The specimen was hydrothermal treated in high-pressure steam at 300$^{\circ}C$ for 2 hours using an autoclave. Then, specimens were immersed in the Hanks' solution with pH 7.4 at 37$^{\circ}C$ for 30 days. The surface of specimen was characterized by scanning electron microscope(SEM), energy dispersive X-ray microanalysis(EDX), potentiostat/galvanostat test, and cytotoxicity test. The results obtained was summarized as follows; According to the result of measuring corrosion behavior at 0.9% NaCl, corrosion resistance was improved more specimens treated with anodic oxide than in hydrothermal treated ones. The multi-porous oxide layer on surface treated through anodic oxidation showed a structure that fine pores overlap one another, and the early precipitation of apatite was observed on the surface of hydrothermal treated samples. According to the result of EDX after 30 days deposition in Hanks' solution, Ca/P was 1.69 in hydrothermal treated specimens. In MTT test, specimens treated through anodic oxidation and hydrothermal treated ones showed spectrophotometer similar to that of the control group. Thus no significant difference in cytotoxicity was observed (P>0.05).

• Asian-Australasian Journal of Animal Sciences
• /
• 제33권12호
• /
• pp.1940-1947
• /
• 2020

Objective: Combination of two stressors on alteration of mineral footprints in animals needs due attention to meet maximum production and welfare, particularly in grazing sheep. This study tested whether ewes (Ovis aries) exposed to water deprivation and thermal-humidity stressors had altered mineral footprints in their wool, serum, urine, and feces. Methods: Nine ewes (age = 3 years; mean body weight = 41±3.5 kg) were divided among a control group with free access to water, and treatment groups with water deprivation lasting either 2 h (2hWD) or 3 h (3hWD) after feeding. Using a 3×3 Latin square design, animals were assigned to treatment groups for three sampling periods of 21 days each (n = 9). Blood was collected by jugular venipuncture. Wool was collected at the end of periods 2 and 3. Metabolic crates designed with metal grated floors were used for urine and feces collection. We measured sodium (Na), magnesium (Mg), phosphorus (P), chloride (Cl), calcium (Ca), manganese (Mn), copper (Cu), iron (Fe), and zinc (Zn). Results: The wool mineral levels did not differ between the treatment groups, although K was marginally lower (p = 0.10) in the 2hWD group. The serum and urine mineral levels did not differ between the treatments (p>0.05). Fecal K was significantly lower in the 2hWD group than in the other groups (p≤0.05). Conclusion: In conclusion, water deprivation and thermal-humidity exposure altered the excretion of K, but not of other minerals, in the wool, urine, feces, or serum of ewes. Thus, no additional mineral supplementation is needed for water deprived ewes during thermalhumidity exposure.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2017년도 춘계학술대회 논문집
• /
• pp.158-158
• /
• 2017

Titanium and its alloys have been used in the field dental and orthopedic implants because of their excellent mechanical properties and biocompatibility. Despite these attractive properties, their passive films were somewhat bioinert in nature so that sufficient adhesion of bone cells to implant surface was delayed after surgical treatment. Recently, plasma electrolyte oxidation (PEO) of titanium metal has attracted a great deal of attention is a comparatively convenient and effective technique and good adhesion to substrates and it enhances wear and corrosion resistances and produces thick, hard, and strong oxide coatings. Silicon(Si), Zinc(Zn), and Manganese(Mn) have a beneficial effect on bone. Si in particular has been found to be essential for normal bone and cartilage growth and development. And, Zn has been shown to be responsible for variations in body weight, bone length and bone biomechanical properties. Also, Mn influences regulation of bone remodeling because its low content in body is connected with the rise of the concentration of calcium, phosphates and phosphatase out of cells. The objective of this work was research on bone-like apatite morphology on Si-Zn-Mn-hydroxyapatite coating on Ti-6Al-4V alloy by plasma electrolytic oxidation. Anodized alloys were prepared at 280V voltage in the solution containing Si, Zn, and Mn ions. The surface characteristics of PEO treated Ti-6Al-4V alloy were investigated using XRD, FE-SEM, and EDS.

• Journal of Microbiology
• /
• 제34권2호
• /
• pp.179-183
• /
• 1996

Streptoccus Pneumoniae (pneumococcus), the most common cause of bacterial pneumonia, has an ample polysaccharide (PS) capsule that is highly antigenic and is the source of PS vaccine. This investigation was undertaken to optimize the culture conditions for the production of capsulard PS by type 1 pneumococcus. Among several culture media, brain heart infusion (BHI) and Casitone based media were found to support luxuriant growth of pneumococcus type 1 at the same level. Because BHI medium is rather expensive and more complex than the Casitone based media, the Casitone based media was uwed to study optimization of the culture condition. The phase of growth which accomodated maximum PS production was logarithmic phase. Concentrations of glucose greater than 0.2% did not ehnahce growth or PS production. Substitution of netrogen sources with other resources or supplementation of various concentrations of metal ion (with the exception of calcium ion) had adverse affects on growth and PS production. On the other hand, low level aeration was beneficial for increased PS production. Addition of 3 mg/1 concentration of methionine, phenylalanine, and threonine were found to enhance growth and PS production. The synerigistic effect of all the favorable conditions observed in pneumococcal growth assays provided a two-fold cummulative increase in capsular PS production.

• 보존과학회지
• /
• 제10권1호
• /
• pp.1-9
• /
• 2001

본 연구의 목적은 전남 고흥 능가사 대웅전과 천왕문에서 발굴된 종이와 섬유의 해부학적 특성과 미량 화학성분을 광학현미경, 화상해석, 주사전자현미경(SEM-EDS)으로 분석하는 것이다. 모든 종이는 닥나무로 식별되었다. 인피섬유에서 분리된 투명막의 존재가 특징적이었다. 대웅전 벽에 붙여 있는 종이가 가장 손상이 심하였으며 천왕문에서 발굴된 책의 종이 세포는 비교적 보존 상태가 양호하였다. 천왕문의 동방지국상 아래에서 발굴된 섬유는 매우 좁은 세포폭을 갖는 실크이었다. SEM-EDS 분석에서 높은 실리카 함량이 발견되었다. 종이 내에서 발견된 칼슘, 철, 염소, 그 밖의 미량원소 분석 결과를 연대, 생산지 및 보존처리와 관련하여 고찰하였다.

• 한국재료학회지
• /
• 제28권5호
• /
• pp.273-278
• /
• 2018

Lithium-ion batteries have been considered the most important devices to power mobile or small-sized devices due to their high energy density. $LixCoO_2$ has been studied as a cathode material for the Li-ion battery. However, the limitation of its capacity impedes the development of high capacity cathode materials with Ni, Mn, etc. in them. The substitution of Mn and Ni for Co leads to the formation of solid solution phase $LiNi_xMn_yCo_{1-x-y}O_2$ (NMC, both x and y < 1), which shows better battery performance than unsubstituted $LiCoO_2$. However, despite a high discharge capacity in the Ni-rich compound (Ni > 0.8 in the metal site), poor cycle retention capability still remains to be overcome. In this study, aiming to improve the stability of the physical and chemical bonding, we investigate the stabilization effect of Ca in the Ni-rich layered compound $Li(Ni_{0.83}Co_{0.12}Mn_{0.05})O_2$, and then Ca is added to the modified secondary particles to lower the degree of cationic mixing of the final particles. For the optimization of the final grains added with Ca, the Ca content (x = 0, 2.5, 5.0, 10.0 at.%) versus Li is analyzed.

• 대한화학회지
• /
• 제30권1호
• /
• pp.118-125
• /
• 1986

약 15g 정도의 소형탄 연소시험 장치를 고안, 제작하여 여러종류의 촉매능이 있는 전이 금속 계열의 화합물, 천연광물 및 산화제등이 첨가된 소형탄 연소시험을 실시하였다. 이들 여러 첨가제중에서 구리성분이 가장 우수한 CO억제효과를 나타냈으며 같은 구리성분의 경우에도 산화물의 형태로 표면적이 넓은 ${\gamma}-Al_2O_3$와 같은 지지체에 분산시켜 사용하는 경우가 가장 효과적이었다. 이 때 구리성분으로 연탄에 대하여 0.5% 첨가하므로서 착화 및 연소초가 CO함량을 1.4 %, 연소말기에는 0.3 %로 낯출수 있었다. 또한 연탄 연소 배기가스중의 황화합물을 줄이기 위한 칼슘화합물의 황고정 효과도 정량적으로 검토하였다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
• /
• 한국우주과학회 2009년도 한국우주과학회보 제18권2호
• /
• pp.30.2-30.2
• /
• 2009

There is a growing body of evidence for the presence of multiple stellar populations in some globular clusters, including NGC 1851. For most of these peculiar globular clusters, however, the evidence for the multiple red giant-branches (RGBs) having different heavy elemental abundances as observed in $\omega$ Centauri is hitherto lacking, although spreads in some lighter elements are reported. It is therefore not clear whether they also share the suggested dwarf galaxy origin of $\omega$ Cen or not. Here we show from the CTIO 4m UVI photometry of the globular cluster NGC 1851 that its RGB is clearly split into two in the U - I color. The two distinct RGB populations are also clearly separated in the abundance of heavy elements as traced by Calcium, suggesting that the type II supernovae enrichment is also responsible, in addition to the pollutions of lighter elements by intermediate mass asymptotic giant branch stars or fast-rotating massive stars. The RGB split, however, is not shown in the V - I color, as indicated by previous observations. Our stellar population models show that this and the presence of bimodal horizontal-branch distribution in NGC 1851 can be naturally reproduced if the metal-rich second generation stars are also enhanced in helium.

• 한국미생물·생명공학회지
• /
• 제20권3호
• /
• pp.263-270
• /
• 1992

채소 등 작물의 부패균인 Erwinia carotovora subsp. carotovora의 생육을 억제하는 길항세균을 경작지 표토층으로부터 분리하고 배양조건에 따른 억제력변화를 조사하고, 길항관련 유전자의 소재를 확인하였다. 분리균들중 가장 우수한 억제력을 갖는 S4, S14, S65 균주를 최종 선발하고 Pseudomonas 근연종으로 동정하였다. 523 배지를 사용하여 배양조건에 따른 억제력 변화를 조사한 결과 배지초기 pH를 7-8로 조정하여 $30^{\circ}C$에서 3일간 배양하였을 때 가장 높은 억제력을 보였고, 배지성분중 탄소원으로 mannitol과 sorbitol, 무기염으로 CaCl2를 첨가했을 때 효과적이었으나 질소원에 대한 감수성은 낮았다.