• 열처리공학회지
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• 제17권6호
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• pp.346-355
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• 2004

The flame quenching process has been employed to modify the surfaces of commercial marine propeller material, aluminum bronze alloy (Cu-8.8Al-5Ni-5Fe), and the microstructure, hardness and wear properties of the flame-quenched layers have been studied. The thermal history was accurately monitored during the process with respect to both the designed maximum surface temperature and holding time. The XRD and EDX analyses have shown that at temperatures above $T_{\beta}$, the microstructure consisting of ${\alpha}+{\kappa}$ phases changed into the ${\alpha}+{\beta}^{\prime}$ martensite due to an eutectoid reaction of ${\alpha}+{\kappa}{\rightarrow}{\beta}$ and a martensitic transformation of ${\beta}{\rightarrow}{\beta}^{\prime}$. The ${\beta}^{\prime}$ martensite phase formed showed a face-centered cubic (FCC) crystal structure with the typical twinned structure. The hardness of the flame-quenched layer having the ${\alpha}+{\beta}^{\prime}$ structure was similar to that of the ${\alpha}+{\kappa}$ structure and depended sensitively on the size and distribution of hard ${\kappa}$ and ${\beta}^{\prime}$ phases with depth from the surface. As a result of the sliding wear test, the wear resistance of the flame-quenched layer was markedly enhanced with the formation of the ${\beta}^{\prime}$ martensite.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제28권5호
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• pp.417-433
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• 2006

Purpose : Platelet rich plasma (PRP) is an autologous material with many growth factors, such as BMPs, PDGF, $TGF-{\beta}_1$, $TGF-{\beta}_2$, VEGF, and IGF, facilitating bone healing process. The prominent osteoconductive activity and the biodegradable nature of beta-tricalciumphosphate (${\beta}-TCP$) for bone grafts in animal experiments have been reported. The purpose of this study was to evaluate the effect of PRP on the osteogenesis of ${\beta}-TCP$. Materials & Methods : Two artificial calvarial bone defects were made in 32 rabbits which were divided into 2 groups. In one group of 16 rabbits, autogenous bone / ${\beta}-TCP$ was grafted on each side of cranial bone defect. In the other group of 16 rabbits, mixture of ${\beta}-TCP$ and PRP / PRP alone was grafted on each side of the cranial bone defect. The animals were sacrificed at 2, 4, 8, and 12 weeks after surgery. The specimens were harvested and examined histologically and immunohistochemically by the expression of BMP2/4/7, PDGF, VEGF and $TGF-{\beta}_1$. Results : The mean volume of new bone formation was significantly higher at 4, 8, 12 weeks in autogenous graft than that in ${\beta}-TCP$. The BMP2/4 expression was significantly higher at 4 weeks in autogenous bone graft and at 4 weeks in mixture of ${\beta}-TCP$ and PRP and at 12 weeks in ${\beta}-TCP$. The expression of BMP7, PDGF, VEGF and $TGF-{\beta}_1$ showed no significant difference in autogenous, ${\beta}-TCP$, mixture of ${\beta}-TCP$ and PRP, and PRP alone during grafted bone regeneration. Conclusion : The results showed that PRP had no additional value in promoting healing process of ${\beta}-TCP$ grafts.

• 한국재료학회지
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• 제21권2호
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• pp.111-114
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• 2011

As a growth-template of ZnO nanorods (NR), a hexagonal $\beta-Ni(OH)_2$ nanosheet (NS) was synthesized with the low temperature hydrothermal process and its microstructure was investigated using a high resolution scanning electron microscope and transmission electron microscope. Zinc nitrate hexahydrate was hydrolyzed by hexamethylenetetramine with the same mole ratio and various temperatures, growth times and total concentrations. The optimum hydrothermal processing condition for the best crystallinity of hexagonal $\beta-Ni(OH)_2$ NS was determined to be with 3.5 mM at $95^{\circ}C$ for 2 h. The prepared $Ni(OH)_2$ NSs were two dimensionally arrayed on a substrate using an air-water interface tapping method, and the quality of the array was evaluated using an X-ray diffractometer. Because of the similarity of the lattice parameter of the (0001) plane between ZnO (wurzite a = 0.325 nm, c = 0.521 nm) and hexagonal $\beta-Ni(OH)_2$ (brucite a = 0.313 nm, c = 0.461 nm) on the synthesized hexagonal $\beta-Ni(OH)_2$ NS, ZnO NRs were successfully grown without seeds. At 35 mM of divalent Zn ion, the entire hexagonal $\beta-Ni(OH)_2$ NSs were covered with ZnO NRs, and this result implies the possibility that ZnO NR can be grown epitaxially on hexagonal $\beta-Ni(OH)_2$ NS by a soluble process. After the thermal annealing process, $\beta-Ni(OH)_2$ changed into NiO, which has the property of a p-type semiconductor, and then ZnO and NiO formed a p-n junction for a large area light emitting diode.

• 한국세라믹학회지
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• 제36권6호
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• pp.655-661
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• 1999

${\beta}$-SiC formation mechanism in Si melt-C-SiC system with varying in size of carbon source was investigated. A continuous reaction sintering process using Si melt infiltration method was adopted to control the reaction sintering time effectively. It was found that ${\beta}$-SiC formation mechanism in Si melt-C-SiC system was directly affected by the size of carbon source. In the Si melt-C-SiC system with large carbon source ${\beta}$-SiC formation mechanism could be divided into two stages depending on the reaction sintering time: in early stage of reaction sintering carbon dissolution in Si melt and precipitation of ${\beta}$-SiC was occurred preferentially and then SIC nucleation and growth was controlled by diffusion of carbon throughy the ${\beta}$-SiC layer formed on graphite particle. Furthmore a dissolution rate of graphite particles in Si melt could be accelerated by the infiltration of Si melt through basal plane of graphite crystalline.

• The Journal of Korean Physical Therapy
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• 제14권3호
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• pp.145-173
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• 2002

This study was performed to investigate the effect of ultrasound irradiation on $TGF-\beta_1$ expression in the surgically injured achilles tendons of rats. The results of this study were as following: 1. The control group (3 days after injury) expressed little immunoreactivity for $TGF-\beta_1$. 2. In the experimental groups, $TGF-\beta_1$ immunoreactivity of group 11(applied US for 3 days) was increased markedly than that of group 1(applied US for 1 day). 3, The experimental group 11(applied US for 3 days) expressed higher immunoreactivity for $TGF-\beta_1$ than control group. These findings suggest that ultrasound irradiation on the injured Achilles tendon may be of benefit such as increasing $TGF-\beta$ release in the inflammatory phase of heal ins process.

• Journal of the Korean Data and Information Science Society
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• 제27권2호
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• pp.451-461
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• 2016

본 연구의 목적은 400병상 이상 종합병원에 근무하는 간호사들의 비판적 사고성향, 간호과정 수행능력과 근거기반실무역량 수준을 파악하고, 비판적 사고성향, 간호과정 수행능력과 근거기반실무역량과의 관계를 파악하여 근거기반실무역량 향상을 위한 기초 자료를 제공하고자 시도되었다. 본 연구는 서술적 상관관계 연구로 종합병원에 근무하는 262명의 간호사를 대상으로 자기기입식 설문지를 통해 조사하였다. 수집된 자료는 SPSS 21.0을 사용하여 통계 분석하였다. 본 연구의 결과 간호사의 비판적 사고성향과 간호과정 수행능력과 근거기반실무역량은 중정도 이상의 수준이었고 간호사의 근거기반실무역량은 비판적 사고성향 (r=.42, p <.001), 간호과정 수행능력 (r=.58, p <.001)과 정적인 상관관계를 나타냈다. 위계적 회귀분석 결과 비판적 사고성향 (${\beta}=.34$, p <.001)과 간호과정 수행능력 (${\beta}=.57$, p <.001)은 근거기반실무역량에 유의한 영향요인으로 나타났다. 이러한 연구결과를 통해서 간호사의 근거기반실무역량 향상을 위해서 간호사의 비판적 사고성향과 간호과정 수행능력의 향상을 위한 전략이 요구되어진다.

• Journal of Microbiology and Biotechnology
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• 제12권5호
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• pp.813-818
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• 2002

Expression of monokine induced by IFN-$\gamma$(Mig) mRNA is well-known to strictly depend on Interferon-$\gamma$(IFN-$\gamma$). Lipopolysaccharide (LPS) alone Is weakly effective on Mig mRNA expression in mouse Peritoneal macrophages. This study was undertaken to investigate the synergistic effect of LPS and IFN-$\beta$ on chemokine Mig gene expression in mouse peritoneal macrophages. Although IFN-$\beta$ alone was minimally effective, LPS plus IFN-$\beta$ synergized to produce a high level of Mig mRNh. The synergistic effect of LPS and IFN-$\beta$ (LPS/IFN-$\beta$) on Mig mRNA expression was strain-specific. The most effective synergistic effect of LPS/IFN-$\beta$ on the mRNh expression was found in simultaneous stimulation of LPS/IFN-$\beta$. This synergy was modulated at the level of the gene transcription and was not dependent on a new protein synthesis. Synergistic effect of LPS/IFN-$\beta$ also required the activation of $NF-_KB$. Accordingly, these data suggest that LPS/IFN-$\beta$ synergizes the expression of Mig mRNA through a process that depends on a pretranscriptional level and/or coincident Mig mRNA transcription.

• Biomolecules & Therapeutics
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• 제20권3호
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• pp.245-255
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• 2012

Amyloid-${\beta}$ peptide ($A{\beta}$) is still best known as a molecule to cause Alzheimer's disease (AD) through accumulation and deposition within the frontal cortex and hippocampus in the brain. Thus, strategies on developing AD drugs have been focused on the reduction of $A{\beta}$ in the brain. Since accumulation of $A{\beta}$ depends on the rate of its synthesis and clearance, the metabolic pathway of $A{\beta}$ in the brain and the whole body should be carefully explored for AD research. Although the synthetic pathway of $A{\beta}$ is equally important, we summarize primarily the clearance pathway in this paper because the former has been extensively reviewed in previous studies. The clearance of $A{\beta}$ from the brain is accomplished by several mechanisms which include non-enzymatic and enzymatic pathways. Nonenzymatic pathway includes interstitial fluid drainage, uptake by microglial phagocytosis, and transport across the blood vessel walls into the circulation. Multiple $A{\beta}$-degrading enzymes (ADE) implicated in the clearance process have been identified, which include neprilysin, insulin-degrading enzyme, matrix metalloproteinase-9, glutamate carboxypeptidase II and others. A series of studies on $A{\beta}$ clearance mechanism provide new insight into the pathogenesis of AD at the molecular level and suggest a new target for the development of novel therapeutics.

• 환경생물
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• 제17권4호
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• pp.493-498
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• 1999

포도박과 같은 쥬기성 폐기물의 퇴비화에서 효소활성도가 퇴비의 안정성 혹은 부숙도를 나타내는 지표로서의 사용가능성이 있는지를 검증하기 위해 $\beta$-glucosidase, cellobiohydrolase 및 alkaline phosphatase의 활성도를 측정하였다. 측정한 모든 효소가 퇴비화초기에 최대의 활성도를 나타냈는데 이는 포도박에 잔류해있던 분해가 용이한 유기물질과 관련이 있는 것으로 추정되며 그 후 활성도는 점차감소하였다. 그러나 퇴비화 60일이 경과한 후에 $\beta$-glucosidase와 cellobiohydrolase활성도는 다시 급격히 상승했고 alkaline phosphatase의 활성도는 큰 변화를 나타내지 않았다. 퇴비화 후반기에 나타나는 이와 같은 효소활성도의 증가는 퇴비의 안정성을 나타내는 하나의 지표로 사용할 수 있음을 시사해 준다.

• Journal of Microbiology and Biotechnology
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• 제1권4호
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• pp.274-280
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• 1991

Effects of IPTG induction on cell growth and production of ${\beta}$-galactosidase-preS2 fusion protein (${\beta}$gal-preS2) were studied in a defined medium using a recombinant Escherichia coli JM109/pCMHB30. IPTG was added (0.2 mM) to induce the cloned-gene expression in the early-, mid-, and late-log growth phases. The most serious decreases in growth rate and plasmid stability were observed for the induction in the early-log growth phase. The expression level of ${\beta}$gal-preS2 attained by the induction in the mid-log phase was about 0.51 mg fusion protein/mg total cellular protein, which was 2- and 5-fold improvement over the levels obtained with the inductions in the early- and late-log phases. Formation of acidic byproducts including acetate and pyruvate showed different profiles during the fermentation period for each cases of induction; pyruvate was the major byproduct for the induction in the early-log phase while acetate production became more significant for the cases of inductions in the mid- and late-log phases.