Earticle

목적: 본 연구는 1,2-octanediol과 1,2-hexanediol을 중심으로 ethyl hexanediol, methylpropanediol, 2-butyl-2-ethyl-1,3- propanediol, ethylhexylglycerin의 알칸디올을 유화 에멀젼 제형에 적용하여 미생물 오염에 대한 보존력과 함께 제형 내 상안정성을 확인하여 다양한 화장품 처방 개발에 기여하고자 한다. 방법: 에멀젼에 적용하여 보존력과 3개월 동안 온도 보관에 따른 상안정성 을 확인하고 섬유아세포의 세포독성과 균주별 항균력을 비교하였다. 결과: 알칸디올류의 알킬선형 탄소 사슬 길이가 길수록 보존력이 우수하나 제형 함유 함량이 높을수록 상안정성에 불안정성이 나타났다. 섬유아세포 세포독성 평가를 통해 세포막을 변형시켜 항균력을 나타나는 관계를 확인하였다. 결론: 탄소수와 다이올의 화학구조에 의한 세포독성과 항균력의 상관관계를 활용하여 향후 미생물 오염에 대한 항균력, 인체에 대한 안전성, 제형의 상안정성 항목에서 상승효과를 부여하는 이상적인 보존제 부스터를 개발 하는데 기여할 것으로 기대된다

Purpose: This study aimed to contribute to the development of various cosmetic formulations by adding alkanediols of ethyl hexanediol, methylpropanediol, 2-butyl-2-ethyl-1,3-propanediol, and ethylhexylglycerin (mainly 1,2-octanediol and 1,2-hexanediol) to emulsion formulations to determine their emulsion phase stability as well as their preservation against microbial contamination. Methods: The alkanediols were added to the emulsions to assess their preservation effects and phase stability under various storage temperatures for 3 months. In addition, their fibroblast cytotoxicity and anti-bacterial activity against microorganisms were compared. Results: A greater preservation effect was observed with longer linear alkanediol alkyl carbon chain lengths. However, higher formulation content revealed instability in phase stability. Furthermore, evaluation of fibroblast cytotoxicity showed that the relationship between cell membrane disruption and antimicrobial activity was affected. Conclusion: Utilizing the correlation between cytotoxicity and antimicrobial activity because of the carbon number and diol chemical structure, these results are expected to contribute to the development of improved preservative boosters that provide synergistic effects in terms of antimicrobial activity against microbial contamination, human safety, and the phase stability of formulations in the future.

目的: 本研究重点关注1,2-辛二醇和 1,2-己二醇，并将乙基己二醇、甲基丙二醇、2-丁基-2-乙基-1,3-丙二醇和乙 基己基甘油等链烷二醇应用于乳液配方中，通过确认配方内的相稳定性和针对微生物污染的防腐能力，为各种 化妆品配方的开发做出贡献。方法: 将链烷二醇添加到乳液中，评估其在不同储存温度下3个月的保存效果和相 稳定性。此外，还比较了它们的成纤维细胞毒性和对微生物的抗菌活性。结果: 线性链烷二醇烷基碳链长度越 长，保存效果越好。然而，较高的配方含量表明相稳定性不稳定。此外，成纤维细胞细胞毒性的评估表明细胞 膜破坏与抗菌活性之间的关系受到影响。结论: 利用由于碳数和二醇化学结构而导致的细胞毒性和抗菌活性之间 的相关性，这些结果有望有助于开发改进的防腐剂增强剂，这些增强剂在针对微生物污染的抗菌活性、人类安 全和配方的相稳定性方面协同效应。

We report the solid-liquid phase equilibria on the GdBa2Cu3O7-δ (GdBCO) stability phase diagram in low oxygen pressures (PO2) ranging from 1 to 100 mTorr. On the basis of the GdBCO stability phase diagram experimentally determined in low oxygen pressures, the isothermal sections of three different phase fields on log PO2 vs. 1/T diagram were schematically constructed within the Gd2O3-Ba2CuOy-Cu2O ternary system, and the solid-liquid phase equilibria in each phase field were described. The invariant points on the phase boundaries include the following three reactions; a pseudobinary peritectic reaction of GdBCO ↔ Gd2O3 + liquid (L1), a ternary peritectic reaction of GdBCO ↔ Gd2O3 + GdBa6Cu3Oy + liquid (L2), and a monotectic reaction of L1 ↔ GdBa6Cu3Oy +L2. A conspicuous feature of the solid-liquid phase equilibria in low PO2 regime (1 - 100 mTorr) is that the GdBCO phase is decomposed into Gd2O3 + L1 or Gd2O3 + GdBa6Cu3Oy + L2 rather than Gd2BaCuO5 + L well-known in high PO2 like air.

이 연구는 성인 애착의 안정성 및 생활적응과의 관계를 6개월에 걸쳐 탐색한 것이다. 145명의 생도가 6개월 간격으로 시행된 두 번의 조사에 참여하였으며 여기에는 관계질문지, 성인애착 척도, 생도생활적응검사가 사용되었다. 연구 결과, 전 생도의 63%가 6개월에 걸쳐 동일한 애착 유형을 나타냈으며 성인 애착 요인에 대한 반응은 어느 정도 안정적인 것으로 나타났다. 성인 애착의 자신감 요인은 생도생활적응검사의 모든 요인과 긍정적인 상관관계를 나타냈으며, 두 번의 측정에서 안정된 애착 유형의 집단은 불안정한 집단에 비해 높은 사회적응 점수를 보였다. 끝으로 본 연구의 제한점과 앞으로의 성인 애착 연구에 주는 시사점이 논의되었다.

This study explored stability in adult attachment and its relation with life adaptation over six months. 145 cadets participated in the survey which was carried two times with six months interval, using the Relational Questionnaire(RQ), the Adult Attachment Scale(AAS) and the Cadets Adjustment to Academy(CAA). Results indicated that 63% of the cadets showed no difference in the adult attachment styles of the RQ and their responses in the adult attachment factors of the AAS were moderately stable after the six months. The confidence factor of the AAS turned out to have positive co-relations with the all factors of the CAA. In the two measurements, the secure attachment group showed a higher score in social adaptation than the insecure group. In the conclusion, the limitations of this study were discussed and the suggestions were made for the future adult attachment studies.

Phase stability diagram and boundary of a- and c-axis orientation of $SmBa_2Cu_3O_{7-y}$ (SmBCO) thin films grown by pulsed laser deposition (PLD) were reported with studies based on x-ray diffraction [1]. Four different samples are systematically analyzed: normal c-axis oriented orthorhombic $SmBa_2Cu_3O_{7-y}$, a-axis oriented $SmBa_2Cu_3O_{7-y}$, c-axis oriented orthorhombic $SmBa_2Cu_3O_{7-y}$ with $Sm_2BaCuO_5$ phase, and a mixture with c-axis oriented orthorhombic $SmBa_2Cu_3O_{7-y}$ and anomalously long-c tetragonal $SmBa_2Cu_3O_x$. Raman scattering spectroscopy equipped with polarization analysis elucidates the crystal orientation and the origin of the growth of the materials. It indicates that the technique can be used for quality control of conductor manufacturing processes as well as for enhancement of the materials properties.

First-principles calculations were carried out to investigate the crystal stability and magnetism of $Fe_{16}C_2$ and $Fe_{16}C_2$. Our precise calculations show that the structure of high carbon phase is $Fe_{16}C_2$ and this structure is more stable in the ferromagnetic state than the nonmagnetic state. The Fe atoms induced negative magnetic moment at the C atoms, which interact with the nearest Fe atoms.

Phase stability and morphological investigation on the $Si/SiO_2/HfO_2$ and $Si/SiO_2/ZrO_2$ stack are presented. Thermal stability of $HfO_2$ and $ZrO_2$ determines the quality of interface and subsequently the performance of device. The stacks have been fabricated and annealed at $1000^{\circ}C$ for various time. In evolution of crystalline phase and morphology (electrical and geometrical) of high-k materials, annealing time and process are observed to be crucial factors. The crystallization of some phase has been observed in the case of $Si/SiO_2/HfO_2$. The chemical environment around Zr and Hf in respective samples is observed to be different.

Bi-2212 and Bi-2223 thin films are prepared by IBS(ion beam sputtering) technique. Three phases of Bi-2201, Bi-2212 and Bi-2223 appear as stable ones in spite of the conditions for thin film fabrication of Bi-2212 and Bi-2223 compositions, depending on substrate temperature (T $_{sub}$) and ozone pressure(PO$_3$). It is found out that these phases are limited within very narrow temperature.e.

Bi2212 and Bi2223 thin films are fabricated by ion beam sputtering method. Three phases of Bi2201, Bi2212 and Bi2223 appear as stable ones in spite of the condition for thin film fabrication of Bi2212 and bi2223 compositions, depending on substrate temperature(T$\sub$sub/) and ozone pressure (PO$_3$). It is found out that these phases show similar T$\sub$sub/ and PO$_3$dependence, and that the stable regions of these phases are limited within very narrow temperature.

Bi2212 and Bi2223 thin films are fabricated by ion beam sputtering method. Three phases of Bi2201, Bi2212 and Bi2223 appear as stable ones in spite of the condition for thin film fabrication of Bi2212 and bi2223 compositions, depending on substrate temperature(T$\sub$sub/) and ozone pressure (PO$_3$). It is found out that these phases show similar T$\sub$sub/ and PO$_3$ dependence, and that the stable regions of these phases are limited within very narrow temperature.

In the present work, hydroxyapatite (HA) derived from calcined eggshell via a wet chemical precipitation method wasinvestigated. The as-received eggshells was calcined at 900 oC to produce crystalline calcium oxide which reacted withorthophosphoric acid under controlled conditions. The final solution was filtered, dried and sieved to obtain ready to press,phase pure hydroxyapatite powder as confirmed by X-ray diffraction (XRD) analysis. Green samples were prepared andsintered in air at various temperatures ranging from 900 oC to 1300 oC at a ramp rate of 10 oC per minute and 1 hr holdingtime. The sintered samples were evaluated in terms of HA phase stability, relative density, grain size, Vickers hardness andfracture toughness. The results showed that the HA phase remained stable even after sintering at 1300 oC. In addition, the relativedensity, Vickers hardness and fracture toughness were found to increase rapidly between 900 to 1100 oC and reached a plateauthereafter. A relatively density of 98.5%, high Vickers hardness of 5.9 GPa and fracture toughness of 1.09 MPam1/2 was achievedat 1250 oC despite having a large grain size of 2.5 μm at this temperature.

Alpha-SiAlON ceramics having various compositions and modifying cations were investigated with respect to their phase stability, transformation kinetics. and resulting microstructures. Each composition was heat treated at 150$0^{\circ}C$ for 1h and measured the $\alpha$-SiAlON transformation. The phase-boundary composition in the single-phase $\alpha$-SiAlON region showed sluggish transformation from $\alpha$-$Si_3N_4$ to $\alpha$-SiAlON compared to the phase-center composition in the diagram. Using the different rare earth modifying cations, dependence of transformation kinetics on the phase stability in a fixed composition was also explained. By changing size of the stable u-phase region with exchanging cations, systematic change in transformation was observed. Transformation rate of $\alpha$-SiAlON at low temperature has an important role on controlling the final microstructure. Less transformation gives more chances to develop elongated grain in the microstructure.

The effect of aliovalent dopants, $ Nb_2O_5$ and MnO, on the phase stability of 12 mol% ceria partially-stabilized zirconia (Ce-TZP) polycrystals was studied. Both dopants (MnO and $ Nb_2O_5$) significantly increased the stability of the tetragonal zirconia phase (Mb temperature lower than liquid nitrogen temperature). The enhancement of the stability of the tetragonal phase in Ce-TZP doped with 1 mol% of Mno(Ce-TZP/MnO) andCe-TZP doped with 1 mol% of $ Nb_2O_5$(Ce-TZP/$ Nb_2O_5$) were explained by the significant reduction of the driving force, -${\Delta}$Gchem, for the tetragonal-to-mono-clinic phase transformation caused by the addition of MnO and $ Nb_2O_5$. The enhanced stability of the tetragonal phase in the Ce-TZP and Al2O3 composite (Ce-TZP/$Al_2O_3$) is believed to be caused by smaller grain size, moderate reduction in the chemical driving force and increase in the strain energy barrier to the transformation. Mechanical properties of the Ce-TZP and the Ce-TZP/$Al_2O_3$ with (i) the same grain size and (ii) the same Mb temperature were examined by measuring stress-strain behavior in 3 point bending. The Ce-TZP/$Al_2O_3$ composite doped with 1.3w% MnO (Ce-TZP/$Al_2O_3$/MnO), which had the same grain size as the Ce-TZP and De-TZP/$Al_2O_3$ showed more transformation plasticity than either the Ce-TZP or the Ce-TZP/$Al_2O_3$ composite. The Ce-TZP wihch had the same Mb temperature as that of the Ce-TZP/$Al_2O_3$/MnO did not show any transformation plasticity.

Alpha-SiAlON ceramics having various compositions and modifying cations were investigated with respect to their phase stability, transformation kinetics, and resulting microstructures. Each composition was heat treated at 1500℃ for 1h and measured the α-SiAlON transformation. The phase-boundary composition in the single-phase α-SiAlON region showed sluggish transformation from α-Si3N4 to α-SiAlON compared to the phase-center composition in the diagram. Using the different rare earth modifying cations, dependence of transformation kinetics on the phase stability in a fixed composition was also explained. By changing size of the stable α-phase region with exchanging cations, systematic change in transformation was observed. Transformation rate of α-SiAlON at low temperature has an important role on controlling the final microstructure. Less transformation gives more chances to develop elongated grain in the microstructure.

A set of $Fe_{1-x}Ni_{x}$ (x=0.10, 0.25, 0.30, 0.35, 0.50, 0.60, 0.75, 0.85) fine particles prepared by the gas evaporation technique was studied by $M\"{o}ssbauer$, XRD and other techniques. The XRD and $M\"{o}ssbauer$ patterns of the sample with x=0.10 ($Fe_{90}Ni_{10}$) were found to be exceptionally different, showing an austenite phase stability when the particles are quenched. This phase stability is quite different from that of the corresponding bulk alloy. Using binomial distrbution fits of the $M\"{o}ssbauer$ spectra of the particles in terms of nearest and next nearest neighbour configurations around the Fe atoms, an analysis of this phase stability is given. The changes in the relative intensities of the resulting magnetic sextets are used to determine the increase in martensite following the austenite-martensite transformation process. The stable austenite can, therefore, be determined. This stability may be related to the oxide surface layer and the small number of atoms of these fine particles.

A perovskite-type ($La_{0.6}Sr_{0.4}Ti_{0.2}Fe_{0.8}O_{3-{\delta}}$) dense ceramic membrane was prepared by polymerized complex method, using citric acid as a chelating agent and ethylene glycol as an organic stabilizer. Effect of Ti addition on lanthanum-strontium ferrite mixed conductor was investigated by evaluating the thermal expansion coefficient, the oxygen flux, the electrical conductivity, and the phase stability. The thermal expansion coefficient in air was $21.19\;{\times}\;10^{-6}/K$ at 473 to 1,223 K. At the oxygen partial pressure of 0.21 atm ($20%\;O_2$), the electrical conductivity increased with temperature and then decreased after 973 K. The decrement in electrical conductivity at high temperatures was explained by a loss of the lattice oxygen. The oxygen flux increased with temperature and was $0.17\;mL/cm^2{\cdot}min$ at 1,223 K. From the temperature-dependent oxygen flux data, the activation energy of oxygen ion conduction was calculated and was 80.5 kJ/mol at 1,073 to 1,223 K. Also, the Ti-added lanthanum-strontium ferrite mixed conductor was structurally and chemically stable after 450 hours long-term test at 1,173 K.

The purpose of this paper was to investigate the effect of a high-energy milling (HEM) process on the particle morphology and the correlation between a thermal treatment and tetragonal/monoclinic nanostructured zirconia powders obtained by a precipitation process. To eliminate chloride residue ions from hydrous zirconia, a modified washing method was used. It was found that the used washing method was effective in removing the chloride from the precipitated gel. In order to investigate the effect of a pre-milling process on the particle morphology of the precipitate, dried $Zr(OH)_4$ was milled using a HEM machine with distilled water. The particle size of the $Zr(OH)_4$ powder exposed to HEM reduced to 100~150 nm, whereas that of fresh $Zr(OH)_4$ powder without a pre-milling process had a large and irregular size of 100 nm~1.5 ${\mu}m$. Additionally, modified heat treatment process was proposed to achieve nano-sized zirconia having a pure monoclinic phase. It was evident that two-step calcining process was effective in perfectly eliminating the tetragonal phase, having a small average particle of ~100 nm with good uniformity compared to the sample calcined by a single-step process, showing a large average particle size of ~300 nm with an irregular particle shape and a broad particle size distribution. The modified method is considered to be a promising process for nano-sized zirconia having a fully monoclinic phase.

STATEMENT OF PROBLEM. Recently Yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) has been introduced due to superior flexural strength and fracture toughness compared to other dental ceramic systems. Although zirconia has outstanding mechanical properties, the phenomenon of decrease in the life-time of zirconia resulted from degradation in flexural strength after low temperature aging has been reported. PURPOSE. The objective of this study was to investigate degradation of flexural strength of Y-TZP ceramics after various low temperature aging treatments and to evaluate the phase stability and micro-structural change after aging by using X-ray diffraction analysis and a scanning electron microscope (SEM). MATERIAL AND METHODS. Y-TZP blocks of Vita In-Ceram YZ (Vita Zahnfabrik, Bad $S\ddot{a}ckingen$, Germany) were prepared in 40 mm (length) $\times$ 4 mm (width) $\times$ 3 mm (height) samples. Specimens were artificially aged in distilled water by heat-treatment at a temperature of 75, 100, 125, 150, 175, 200, and $225^{\circ}C$ for 10 hours, in order to induce the phase transformation at the surface. To measure the mechanical property, the specimens were subjected to a four-point bending test using a universal testing machine (Instron model 3365; Instron, Canton, Mass, USA). In addition, X-ray diffraction analysis (DMAX 2500; Rigaku, Tokyo, Japan) and SEM (Hitachi s4700; Jeol Ltd, Tokyo, Japan) were performed to estimate the phase transformation. The statistical analysis was done using SAS 9.1.3 (SAS institute, USA). The flexural strength data of the experimental groups were analyzed by one-way analysis of variance and to detect statistically significant differences ($\alpha$= .05). RESULTS. The mean flexural strength of sintered Vita In-Ceram YZ without autoclaving was 798 MPa. When applied aging temperature at below $125^{\circ}C$ for 10 hours, the flexural strength of Vita In-Ceram YZ increased up to 1,161 MPa. However, at above $150^{\circ}C$, the flexural strength started to decrease. Although low temperature aging caused the tetragonal-to-monoclinic phase transformation related to temperature, the minimum flexural strength was above 700 MPa. CONCLUSION. The monoclinic phase started to appear after aging treatment above $100^{\circ}C$. With the higher aging temperature, the fraction of monoclinic phase increased. The ratio of monoclinic/tetragonal + monoclinic phase reached a plateau value, circa 75% above $175^{\circ}C$. The point of monoclinic concentration at which the flexural strength begins to decrease was between 12% and 54%.

In this work, styrene butadiene rubber (SBR) and styrene butadiene styrene (SBS) were used to modify asphalt, resulting in SBR- and SBS-modified asphalt, respectively. The two modified asphalts were emulsified with a nonionic emulsifier (Span 60) and cationic emulsifiers (ID, DDA) and their phase stabilization was investigated via particle size, Zeta potential, and flow behavior analysis. With increasing amount of the mixed emulsifier, the particle size decreased, leading to an increase in viscosity. The shear thinning behaviors and Zeta potential values ranging from 35-65 mV were determined and remained considerably stable. In addition, the adhesion strength and compression strength of the SBR-and SBS-modified asphalt emulsion were evaluated via surface free energy examination. The remarkable adhesion and compression strengths were estimated when 5 phr ID and 6 phr DDA were added to the emulsified asphalt modified with SBR and SBS. Therefore ID and DDA, the two cationic surfactants, played significant roles in improving the dispersion and interfacial adhesion strength, resulting in the improved adhesion and compression strength of the emulsified asphalts modified with SBR and SBS.