• Korean Journal of Materials Research
• /
• v.4 no.3
• /
• pp.319-328
• /
• 1994

Aluminium and titanium precursors containing $\beta$-diketonate ligands were used for the synthesis of polymeric sols of alumina and titania by sol-gel methods. To prepare polymeric sols by solgel processing, we synthesized modified precursors having chelating organic ligands. With these precursors it was found to be possible to control both hydrolysis and polycondensation reaction rates which resulted in ultrafine particles few nms of average size. The optimum molar ratio of acid to alkoxide for alumina sol was 0.3-0.4 and that of water to alkoxide &as 1. On the other hand, the corresponding ratios for titania sol were found be 0.25-0.20 and 1 respectively. Dynamic light scattering measurements indicated that the average particle size in both sols was in the order of few nms. SEM photographs were taken to observe crack-free and smooth surfaces of coated membranes after sintering at $450^{\circ}C$. Alumina coated membrane on a slide glass had about 4-4.5$\mu \textrm{m}$, thickness and titania coated one had 2-2.5$\mu \textrm{m}$, thickness. And according to TEM photographs, the grain size of titania was smaller than 30nm and that of alumina was in the range of few $\AA$s to 2nms. An X-ray diffraction study revealed that alumina was $\gamma$ phase and titania was anatase crystal.

• Polymer(Korea)
• /
• v.39 no.2
• /
• pp.323-328
• /
• 2015

Poly(${\varepsilon}$-caprolactone) (PCL) nanofibers and PCL/silica membranes were synthesized by sol-gel derived electrospinning and casting, respectively. Smooth PCL nanofibers were obtained from the precursor containing N,N-dimethylformamide (DMF). PCL/silica membranes were prepared by varying the tetraethyl orthosilicate (TEOS) contents from 0 to 40 vol% to investigate the effect of silica addition on mechanical properties and cytotoxicity of the membranes. Although the strength of the membranes decreased from 12 to 8 MPa with increasing the silica content, the strength remained almost constant 7 weeks after dipping in phosphate buffered saline solution (PBS). The strength reduction was attributed to the presence of a patterned surface pores and micro-pores present in the walls between pores. The crystal structure of the membranes was orthorhombic and the crystallite size decreased from 57 to 18 nm with increasing the silica content. From the agar overlay test, the PCL/silica membranes exhibited neither deformation and discoloration nor lysis of L-929 fibroblast cells.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.2
• /
• pp.225-236
• /
• 2013

Among several bacteria examined, an antibacterial-producing Lactobacillus strain with probiotic characteristics was selected and identified based on 16S rRNA gene sequencing. Subsequent purification and mode of action of the antibacterial compounds on target cells including E. coli were investigated. Maximum production of the antibacterial compound was recorded at 18 h incubation at $30^{\circ}C$. Interestingly, antibacterial activity remained unchanged after heating at $121^{\circ}C$ for 45 min, 24 h storage in temperature range of $70^{\circ}C$ to room temperature, and 15 min exposure to UV light, and it was stable in the pH of range 2-10. The active compounds were inactivated by proteolytic enzymes, indicating their proteinaceous nature, and, therefore, referred to as bacteriocin-like inhibitory substances. Isolation and partial purification of the effective agent was done by performing ammonium sulfate precipitation and gel filtration chromatography. The molecular mass of the GFC-purified active compound (~3 kDa) was determined by Tris-Tricine SDS-PAGE. To predict the mechanisms of action, transmission electron microscopy (TEM) analysis of ultrathin sections of E. coli before and after antibacterial treatment was carried out. TEM analysis of antibacterial compounds-treated E. coli demonstrated that the completely altered bacteria appear much darker compared with the less altered bacteria, suggesting a change in the cytoplasmic composition. There were also some membrane-bound convoluted structures visible within the completely altered bacteria, which could be attributed to the response of the E. coli to the treatment with the antibacterial compound. According to the in vivo experiments oral administration of L. plantarum HKN01 resulted in recovery of infected BALB/c mice with Salmonella enterica ser. Typhimurium.

• Korean Journal of Food Science and Technology
• /
• v.29 no.3
• /
• pp.417-426
• /
• 1997

Rice bran protein hydrolysates were prepared and some of their physicochemical properties were investigated to utilize rice bran as starting material for functional food ingredient. Rice bran proteins (RBP) were prepared from defatted rice bran by alkaline extraction and isoelectric precipitation. The enzyme for hydrolysis of RBP was selected through measuring relative activity by pH-drop method and comparing the degree of hydrolysis (DH) of hydrolysates. The enzymatic hydrolysates prepared by $Esperase^{\circledR}$ treatment were partitioned into two fractions by ultrafiltration(UF) with a 10 kDa molecular weight cut-off membrane. Each fraction was applied to a cholic acid-conjugated ${\omega}-aminohexyl$ Sepharose 4B column and the bile acid-binding components were obtained by eluting with deoxycholate. Gel permeation chromatography on a Sephadex G-50 column revealed that molecular weight of the bile acid-binding fraction of UF permeate was distributed in ranges of $2\;kDa{\sim}10\;kDa$ and $0.2\;kDa{\sim}0.6\;kDa$. Three peaks (R-1, R-2 and R-3) were obtained by prep-HPLC of bile acid-binding fraction of UF retentate and analyzed for total and free amino acid composition. The results showed that proline content of the bile-acid binding polypeptides and peptides was four times as much as that of rice bran protein and that the peak corresponding to higher average hydrophobicity had a higher free amino acid content. Average hydrophobicity slightly increased with enzymatic hydrolysis.

• Journal of Periodontal and Implant Science
• /
• v.35 no.3
• /
• pp.549-561
• /
• 2005

이 연구의 목적은 새로이 제작된 chitosan-poly(L-lactic acid)(PLLA) 다층 다공성 차폐막의 생체적합성 및 골세포활성도 및 골재생능을 평가하는 것이다. 제작된 차폐막을 24 well에 넣고 clonal osteoblast-like cell line(MC3T3-E1)을 접종한 군을 실험군으로, 차폐막을 사용하지 않은 대조군으로 하였다. 배양 1일, 7일 및 14일째에 각 well에서 세포수를 측정하였다. 주사전자현미경을 이용하여 차폐막에 부착된 세포의 형태관찰을 시행하였다. RNA 추출 및 RT-PCR을 실시한 후, agarose gel상에서 전기영동하여 조골세포 표식자인 collagen type I(COL), osteopontin(OP) 및 osteocalcin(OC) mRNA의 발현을 관찰하였다. 제작된 매트릭스의 생체적합성 및 골재생능을 관찰하기 위하여 백서의 두개골에 직경 8mm의 원형 결손부를 형성한 후 차폐막을 이식한 군을 실험군으로, 아무 것도 넣지 않은 군을 대조군으로 하여 4주 경과 후 실험동물을 희생시킨 후 조직학적관찰을 시행하였다. 시간경과에 따른 부착세포수 관찰결과, 배양 14일까지 조골세포의 수가 지속적으로 증가하였고, 주사전자현미경으로 세포의 형태 관찰결과, 배양된 세포들은 중층의 형태로 성장하면서 시간경과에 따라 세포가 응집되는 양상을 나타내었다. 관찰 기간동안 COL, OP, 및 OC mRNA의 발현이 관찰되어 배양 전 기간동안 조골세포의 형질이 잘 유지되고 있음을 알 수 있었다. 백서 두개골 결손부에 이식된 차폐막은 염증반응 없이 주위 조직과 우수한 생체적합성을 나타내었으며, 차폐막을 이식하지 하지 않은 대조군에 비해 높은 신생골 형성을 나타내었다. 이상의 관찰결과로 새로이 제작된 chitosan-PLLA 차폐막은 우수한 생체적합성 및 골재생능을 나타냄을 알 수 있었으며, 향후 이를 골조직 재생 및 치주조직유도재생 분야에 응용될 수 있을 것으로 생각된다.

• Korean Journal of Metals and Materials
• /
• v.56 no.12
• /
• pp.885-892
• /
• 2018

Molybdenum disulfide ($MoS_2$) based electrocatalysts have been proposed as substitutes for platinum group metal (PGM) based electrocatalyst to hydrogen evolution reaction (HER) in water electrolysis. Here, we studied $MoS_2/CNFs$ hybrid catalyst prepared by electrospinning method with heat treatment for polymer electrolyte membrane(PEM) water electrolysis to improve the HER activity. The physicochemical and electrochemical properties such as average diameter, crystalline properties, electrocatalitic activity for HER of synthesized $MoS_2/CNFs$ were investigated by the Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Raman Spectroscopy (Raman) and Linear Sweep Voltammetry (LSV). The as spun ATTM/PVP nanofibers were prepared by sol-gel and electrospinning method. Subsequently, the $MoS_2/CNFs$ was dereived from reduction heat treatment of ATTM at the ATTM/PVP nanofibers and carbonization heat treatment. Synthesized $MoS_2/CNFs$ electrocatalyst had an average diameter of $179{\pm}30nm$. We confirmed that the $MoS_2$ layers in $MoS_2/CNF$ electrocatalyst consist of 3~4 layers from the Raman results. In addition, We confirmed that the $MoS_2$ layers in $MoS_2/CNF$ catalyst consist of 7.47% octahedral 1T phase $MoS_2$, 63.77% trigonal prismatic 2H phase $MoS_2$ with 28.75% $MoO_3$ through the XRD, Raman and XPS results. It was shown that $MoS_2/CNFs$ had the overpotential of 0.278 V at $10mA/cm^2$ and tafel slope of 74.8 mV/dec in 0.5 M sulfuric acid ($H_2SO_4$) electrolyte.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.44 no.3
• /
• pp.211-218
• /
• 2018

Instant face lifting cosmetics contain various film forming agents for stretching the wrinkles on the skin surface. But, most of the film-forming polymers have sticky feels. And they are easily scrubbed out when skin is rubbed on. In this study, we focused on the influence of sodium silicate that has rapid film forming effect on skin surface and immediate wrinkle reducing effect. Sodium silicate, also known as water glass or soluble glass, is a compound containing sodium oxide and silica. Sodium silicate is a white powder that is readily soluble in water, producing an alkaline solution. Sodium silicate is stable in neutral and alkaline solutions. The sodium silicate solution hardens by drying in air and rapidly forms a thin film. When the solution is applied to the skin, the fine membrane coating is formed by water evaporation and ionic bond re-formation. It also makes the strong siloxane (Si-O) bonding on the skin surface. When these fixation properties are applied to cosmetics, they can give remarkable skin tightening effect. The sodium silicate solution can provide the lifting effect by forming a film on skin at a proper concentration. But, skin irritation may be caused with too high concentration of sodium silicate. We studied a desirable range of the sodium silicate concentration and combination with other fixatives for skin care formulation that has no sticky feels and no scrubbing out phenomenon. Immediate lifting gel was developed by using sodium silicate and various thickening systems. Among of the various thickeners, aluminum magnesium silicate showed the best compatibility with sodium silicate for rapid lifting effect. This instant physical lifting gel was confirmed as a low stimulating formula by skin clinical test.

• Tuberculosis and Respiratory Diseases
• /
• v.40 no.2
• /
• pp.98-103
• /
• 1993

Background: Inactivation of retinoblastoma gene (Rb) has been observed in a variety of human cancers. Loss of heterozygosity (LOH) of Rb which is a common mode of allelic inactivation of Rb, has been known as a frequent genetic event in small cell lung cancer but it has been detected less frequently in non-small cell lung cancer. To define the role of Rb deletion in lung cancer, we investigated the genomic DNAs of 43 non-small cell lung cancers and 1 small cell lung cancer paired with normal lung tissues obtained by thoracotomy. Methods: The genomic DNAs were obtained by the digestion with proteinase K followed by phenol-chloroform extraction method. The genomic DNAs were digested by restriction endonuclease (EcoRI), separated by agarose gel electrophoresis, transferred to nylon membrane by Southern blot transfer and then hybridized with labelled Rb 1 probe which contains. 1.4 kb sized DNA sequence containing N-terminal portion of Rb. Results: In 26 squamous cell lung cancers, 16 cases were informative after EcoRI digestion and LOH of Rb was found in 10 cases (62.5%). In 17 adenocarcinomas of lung, 11 cases were informative and LOH of Rb was found in five cases (45.4%). The analysis of clinical parameters revealed no significant differences between the two groups with or without LOH of Rb in the aspects of age, sex, degree of differentiation, stage and smoking amount. Conclusions: These results suggest that Rb inactivation is also significantly involved in the molecular pathogenesis of non-small cell lung cancer.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.19 no.2
• /
• pp.87-96
• /
• 2003

The purposes of this study were to find out the optimum intensity of magnetic field where magnetism could promote the activity of osteoblast, and to discover the possibility of clinical application in the areas of dental implants and bone grafts by confirming the effect of clinically increasing bone formation. In this experiment, we used the Neodymium magnet, which had magnetic power six times as strong as the current ones and enabled the resistances against the demagnetization up to 20 to 50 times to be minimized with the size of 1mm in sight. In order to culture cells, a specially designed device was used. It was made to adjust the distance and accordingly to control the intensity of the magnetic field, by placing the cell culture plate in the center with a magnet of 1mm long and thick installed on the both ends. Using MC3T3-E1 cell, a kind of osteoblast-like cell, we cultured, for 24 hours, not only the test group which had been cultured under the magnetic fields with different intensity of 5, 10, 50, 100, 500, and 1000 Gauss, but also the control group excluding the influences of the magnetic field. After observing the cell's form and the density of the culture medium through an inverted microscope, we made a series of proceedings needed for the immunofluoroscence staining, such as fixation, normal serum reaction, primary antibody reaction, and secondary antibody reaction. And with a fluorescence microscope, we observed those-above and compared the frequency of expression of IFG-1 receptor. To make a Western immunoblotting analysis, the cells cultured under the same condition as the above had the procedure of the lysis buffer and the acrylamide gel electrophoresis was carried out. Protein transferred into the nitrocellulose membrane and tested on the primary and the secondary antibody reactions was observed and compared. The results were as follows: When observed through an inverted microscope, the nuclear divisions of the cells under the magnetic field of 10 Gauss were the most active, and the density of the cells could be observed the most enormously. As the result of an immunofluoroscence staining of IGF-1 receptor, the expression of IFG-1 was the most frequently observed under the magnetic field of 10 Gauss. On the other hand, few differences of consideration were made between the test group cultured under the magnetic fields of 5, 500, and 1000 Gauss and the control group. In respect of the expression of IFG-1 receptor, the test group cultured under the magnetic fields of 50 and 100 Gauss were higher than the control group, and lower than that cultured under the magnetic field of 10 Gauss.(p<0.05) According to the Western immunoblotting analysis, the band of IFG-1 receptor which had 85KDa of molecular weight was the darkest. Judging from the above-mentioned results, the growth factor receptor of an osteoblast cell which was an important criterion for the bone formation was increased in maximum under the magnetic field of 10 Gauss. Moreover it was observed that the optimum intensity of magnetic field in which magnetism made the activity of the osteoblast cell increase was about 10 Gauss.