• 한국재료학회지
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• 제28권4호
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• pp.208-213
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• 2018

Epitaxial ($11{\bar{2}}0$) a-plane GaN films were grown on a ($1{\bar{1}}02$) R-plane sapphire substrate with photoresist (PR) masks using metal organic chemical vapor deposition (MOCVD). The PR mask with striped patterns was prepared using an ex-situ lithography process, whereas carbonization and heat treatment of the PR mask were carried out using an in-situ MOCVD. The heat treatment of the PR mask was continuously conducted in ambient $H_2/NH_3$ mixture gas at $1140^{\circ}C$ after carbonization by the pyrolysis in ambient $H_2$ at $1100^{\circ}C$. As the time of the heat treatment progressed, the striped patterns of the carbonized PR mask shrank. The heat treatment of the carbonized PR mask facilitated epitaxial lateral overgrowth (ELO) of a-plane GaN films without carbon contamination on the R-plane sapphire substrate. Thhe surface morphology of a-plane GaN films was investigated by scanning electron microscopy and atomic force microscopy. The structural characteristics of a-plane GaN films on an R-plane sapphire substrate were evaluated by ${\omega}-2{\theta}$ high-resolution X-ray diffraction. The a-plane GaN films were characterized by X-ray photoelectron spectroscopy (XPS) to determine carbon contamination from carbonized PR masks in the GaN film bulk. After $Ar^+$ ion etching, XPS spectra indicated that carbon contamination exists only in the surface region. Finally, the heat treatment of carbonized PR masks was used to grow high-quality a-plane GaN films without carbon contamination. This approach showed the promising potential of the ELO process by using a PR mask.

• 한국약용작물학회지
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• 제11권4호
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• pp.298-305
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• 2003

Polygalae Radix (PR) from Polygala tenuifolia. (Polygalaceae) is traditionally used in China and Korea, since this herb has a sedative, antiinflammatory, and antibacterial agent. To extend pharmacological actions of PR in the CNS on the basis of its CNS inhibitory effect, the present study examined whether PR has the neuroprotective action against kainic acid (KA) -induced cell death in primarily cultured rat cerebellar granule neurons. PR, over a concentration range of 0.05 to $5{\mu}g/ml$ inhibited KA $(500\;{\mu}M)$-induced neuronal cell death, which was measured by a trypan blue exclusion test and a 3-[4,5-dimethylthiazol-2-y1]-2,5-diphenyl-tetrazolium bromide (MTT) assay. PR $(0.5{\mu}g/ml)$ inhibited glutamate release into medium induced by KA $(500\;{\mu}M)$, which was measured by HPLC. Pretreatment of PR $(0.5{\mu}g/ml)$ inhibited KA $(500\;{\mu}M)$-induced elevation of cytosolic calcium concentration $([Ca^{2+}]_c)$ which was measured by a fluorescent dye, Fura 2-AM, and generation of reactive oxygen species (ROS). These results suggest that PR prevents KA-induced neuronal cell damage in vitro.

• Journal of Preventive Medicine and Public Health
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• 제57권1호
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• pp.8-17
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• 2024

Objectives: The effectiveness and efficiency of pre-exposure prophylaxis (PrEP) in reducing the transmission of human immunodeficiency virus (HIV) among men who have sex with men (MSM) relies on how widely it is adopted and adhered to, particularly among high-risk groups of MSM. The meta-analysis aimed to collect and analyze existing evidence on various factors related to PrEP adherence in MSM, including demographic characteristics, sexual behaviors, substance use, and psychosocial factors. Methods: The meta-analysis followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The search included articles published between January 2018 and December 2022, obtained from the PubMed, ScienceDirect, and Scopus databases. The studies that were included in the analysis reported the proportion of MSM who demonstrated adherence to PrEP and underwent quality appraisal using the Newcastle-Ottawa Scale. Results: Of the 268 studies initially identified, only 12 met the inclusion criteria and were included in the final meta-analysis. The findings indicated that education (odds ratio [OR], 1.64; 95% confidence interval [CI], 1.12 to 2.40), number of sexual partners (OR, 1.16; 95% CI, 1.02 to 1.31), engaging in sexual activities with an human immunodeficiency virus-positive partner (OR, 1.59; 95% CI, 1.16 to 2.26), substance use (OR, 0.83; 95% CI, 0.70 to 0.99), and lower levels of depression (OR, 0.55; 95% CI, 0.37 to 0.82) were associated with higher rates of PrEP adherence among MSM. Conclusions: Despite these findings, further research is necessary to investigate PrEP adherence more comprehensively. The findings of this meta-analysis can be utilized to inform interventions aimed at improving PrEP adherence among MSM and provide directions for future research in this area.

• Korean Chemical Engineering Research
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• 제47권4호
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• pp.465-469
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• 2009

산소-공융염(LiCl-KCl) 기포탑에서 4종의 희토류염화물($Ce/Nd/Pr/EuCl_3$)의 산화반응 특성에 대한 연구를 수행하였다. HSC Chemistry software를 이용한 모델링 결과 산소 및 희토류염화물이 존재하는 계에서 가장 안정된 화합물은 옥시염화물(EuOCl, NdOCl, PrOCl)과 산화물($CeO_2$, $PrO_2$)이었으며, 이러한 결과는 옥시염화물 및 산화물이 형성되는 반응의 Gibbs 자유에너지 경향성과도 일치하였다. 실험결과 공융염 내에서 산소와 희토류염화물과의 반응으로 산소분산 시간 및 공융염 온도와 상관없이 Eu, Nd, Pr은 옥시염화물로, Ce, Pr은 산화물형태의 침전물로 형성되었으며, 이러한 결과는 열역학적 데이터를 이용한 모델링 결과와 일치하였다. 4종의 복합희토류 침전물은 등방형태와 정방형태의 침전물로 구분되었는데 주사전자현미경(SEM-EDS) 분석결과 등방구조(cubic structure) 형태의 침전물은 산화물이었고, 정방형 구조(tetragonal structure)의 침전물은 옥시염화물이었다. 실험에 사용된 4종의 희토류염화물의 공융염에 불용성인 침전물로의 전환효율은 온도 및 분산시간이 증가하면 증가하였으며, Ce가 가장 빠른 반응특성을 나타내었다. $650^{\circ}C$의 공융염 온도 및 420분의 산소분산시간 조건에서 4종의 희토류염화물의 산화효율은 모두 99% 이상이었다.

• Toxicological Research
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• 제22권4호
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• pp.431-438
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• 2006

The object of this study was to obtain acute toxicity information (single oral dose toxicity) of lyophilized water extract of Puerariae Radix (PR) in both male and female mice. In order to investigate the 50% lethal dose $(LD_{50})$, approximate lethal dosage (ALD), test substances were once orally administered to female and male ICR mice at dose levels of 2000 and 0 (control) mg/kg (body wt.) according to the recommendation of KFDA Guidelines [2005-60, 2005]. The mortality and body weight changes, clinical signs and gross observation were monitored during 14 days after dosing. Organ weight and histopathology of 12 principal organs were measured. As the results, we could not find any mortality, clinical signs, body weight changes and gross findings except for PR extracts unrelated sporadic findings. In addition, no abnormal changes related PR extracts treatment on the organ weight and histopathology of principal organs were detected except for some sporadic findings including hyperplasia of lymphoid follicles in the popliteal lymph nodes and spleen as pharmacological effects of PR extracts. The results obtained in this study suggest that the PR extracts does not cause any toxicological signs except for pharmacological effects of enhancement of Immune system. The $LD_{50}$ and ALD of PR extracts in both female and male mice were considered as over 2000 mg/kg because no mortalities were detected up to 2000mg/kg that was the highest dose recommended by KFDA and Organization for Economic Co-Operation and Development.

• Bulletin of the Korean Chemical Society
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• 제24권5호
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• pp.566-568
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• 2003

The phosphor $CaTiO_3:Pr^{3+}$ attracts much attention as a low-voltage red phosphor because of its good chromaticity and intrinsic conductivity. The addition of Ga into this CaTiO₃:Pr led the luminance intensity to greatly enhance without the change of the wavelength for the electronic transition and the peak shape of it. The increase of the recombination rate of electron-hole pairs through the Ga ion doping, which was expected to play a role of a hole-trap center, is proposed to be one of the reasons for the enhancement of the cathodoluminescence intensity.

• 한국가스학회지
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• 제14권2호
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• pp.22-26
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• 2010

본 연구에서는 PC-SAFT 모델식을 활용하여 메탄과 에탄의 온도에 따른 증기압과 기상 및 액상에서의 밀도를 추산하였으며, 그 결과를 PR 상태방정식과 비교하였다. 기상의 밀도에 대해서는 두 모델이 모두 실험 데이터를 잘 추산하였으며, 액상의 밀도에 대해서는 PR 상태방정식보다 PC-SAFT 모델식이 좀 더 정확함을 알 수 있었다. 한편 메탄과 에탄 이성분계에 대한 기-액 상평형 실험 데이터에 대해서 두 모델식을 이용하여 추산하였는데 PC-SAFT 모델식이 PR 상태방정식보다 좀 더 우수함을 알 수 있었다.

• 한국미생물·생명공학회지
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• 제43권2호
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• pp.91-96
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• 2015

Prion은 양의 scrapie, 소의 bovine spongiform encephalopathy와 사람의 CJD와 같은 다양한 신경 퇴행성 질환을 유발시키는 단백질 병원체이다. 정상 prion 단백질인 PrP^C가 병원성 PrP^Sc로 바뀌는 과정에 대해서는 많은 연구가 진행되었고, PrP^Sc로의 단백질 구조 변화가 다양한 환경적 요소에 의해서 영향 받는 것으로 추측된다. 바다조류로부터 분리된 MAAs는 다양한 스트레스 환경에서 조류를 보호해주는 것으로 알려져 있다. 이와 같은 사실에 기초하여 mycosporineglycine, porphyra-334와 shinorine 3종의 MAAs로 처리한 prion 감염 신경세포 주에서 prion 단백질 축적의 변화를 평가하였다. PK 저항성을 갖는 PrP^Sc를 western blot 방법으로 확인한 결과, MAA에 의해서 PrP^Sc 단백질의 증식을 관찰하였다.

• 자원리싸이클링
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• 제26권4호
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• pp.79-87
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• 2017

Cyanex 572에 의한 경희토류 다성분 혼합 용액에서 La, Ce, Pr, Nd, Sm의 분리특성에 대해 연구하였다. 5성분계 혼합 용액에서 추출제 농도가 증가할수록 5성분 모두 $pH_{50}$(추출율이 50%인 pH) 값은 감소하였다. 추출제 농도 0.6 M 이상에서 La과 Ce, Nd와 Sm 는 10 이상의 분리계수 값을 보인 반면, Ce과 Pr, Pr과 Nd 사이의 분리계수는 0.5~2.2로 낮았다. 분리계수 개선을 위해 0.6 M Cyanex 572에 TBP를 첨가하였으나 상 분리 속도나 분리계수 개선 효과는 나타나지 않았다. 실험 결과를 고찰한 결과, La/(Pr, Nd, Sm) 그룹과 (Pr, Nd)/Sm 의 경우는 그룹 별 분리는 가능할 것으로 보이나, (La, Ce) 과 (Pr, Nd)의 그룹분리는 Ce와 Pr 사이의 분리계수가 낮아 어려울 것으로 사료된다.

• Journal of Acupuncture Research
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• 제22권6호
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• pp.1-15
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• 2005

Objectives : The aim of this study was to investigate the effect of Peucedani Radix herbal acupuncture(PR-HA) at St36(joksamni) on ovalbumin-induced asthma in mice. Methods : C57BL/6 mice were sensitized and challenged with OVA(ovalbumin) for 12 weeks(once a week) C57BL/6 mice were injected, inhaled and sprayed with OVA for 12 weeks (3times a week). One of the two experimental groups was just treated with needle-prick on St36 and the other group was treated with 1% concentrations of PR-HAS at St36, for the later 8 weeks (3times /week). Results : 1. The weight and total cells of lung of the mice group treated with PR-HA decreased significantly compared with those of control group. 2. Total Leukocytes and Eosinophils in BALF of the mice group treated with PR-HA decreased significantly compared with those of control group. 3. Eosinophils in BALF of the mice group treated with PR-HA in Photomicrographs decreased significantly compared with those of control group. 4. According to Histological analysis of lung sections, it decreased significantly adhension of collagen in PR-HA than those of control group 5. The concentration of IgE, IL-4, IL-5, in BALF and IL-4, IL-5, Il-13 in serum of the mice group treated with PR-HA decreased significantly compared with that of control group. 6. The number of Gr-1+/CD11b+, CD11b+, CD3-/CCR3+, CD4+, CD3e+/CD69+ , CD23+B220+ cells in the lungs of the mice group treated with PR-HA decreased significantly compared with those of control group. 7. The cytokine's manifestation of mRNA of the mice group treated with PR-HA with RT-PCR decreased significantly compared with that of control group. Conclusion : We conclude that PR-HA is effective on OVA-induced asthma of C57BL/6 mouse.