• 한국분말재료학회지
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• 제24권2호
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• pp.141-146
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• 2017

$Bi_2Te_3$ powders are recovered by wet chemical reduction for waste n-type thermoelectric chips, and the recovered particles with different morphologies are prepared using various surfactants such as cetyltrimethylammonium bromide (CTAB), sodium dodecylbenzenesulfonate (SDBS), and ethylenediaminetetraacetic acid (EDTA). When citric acid is added as the surfactant, the shape of the aggregated particles shows no distinctive features. On the other hand, rod-shaped particles are formed in the sample with CTAB, and sheet-like particles are synthesized with the addition of SDBS. Further, particles with a tripod shape are observed when EDTA is added as the surfactant. The growth mechanism of the particle shapes depending on the surfactant is investigated, with a focus on the nucleation and growth phenomena. These results help to elucidate the intrinsic formation mechanism of the rod, plate, and tripod structures of the $Bi_2Te_3$ recovered by the wet reduction process.

• 대한화학회지
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• 제54권4호
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• pp.437-442
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• 2010

수용액 속에서 $NaHSO_4$, TBAB (phase transfer catalyst), ionic liquid (IL) (1-butyl-3-methyl imidazolium hydrogen sulphate [bmim]$HSO_4$)를 사용하여, formalin, ${\beta}$-naphthol, aromatic amines을 반응시켜서 대응하는 2,3-dihydro-2-phenyl-1Hnaphtho-[1,2-e] [1,3] oxazine 유도체를 합성할 수 있는 보다 친환경적이고, 수율이 좋고, 크로마토그래피 분리 방법을 사용하지 않는 합성 방법을 개발하였다.

• BMB Reports
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• 제38권3호
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• pp.281-289
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• 2005

Tumor necrosis factor (TNF) signaling is mediated via two distinct receptors, TNFR2 and TNFR1, which shows partially overlapping signaling mechanisms and biological roles. In the present study, TNFR2 and TNFR1 signal transduction mechanisms involved in activation of $NF{\kappa}B$ and CMV promoter-enhancer were compared with respect to their susceptibility towards inhibitors of intracellular signaling. For this, we used SW480 cells, where we have shown that TNF-signaling can occur independently through each of the two receptors. The TNFR1 response was inhibited by D609, bromophenacyl bromide (BPB), nordihydroguararetic acid (NDGA), and by sodium salicylate, while TNFR2-mediated activation of $NF{\kappa}B$ and CMV promoter-enhancer was resistant to these compounds. The signaling mechanisms known to be affected by these inhibitors include phospholipases as well as redox- and pH-sensitive intracellular components. Our results imply that TNFR2 signaling involved in $NF{\kappa}B$ activation proceeds independently of these inhibitor-sensitive signaling components, indicating distinct signaling pathways not shared with TNFR1.

• 대한의생명과학회지
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• 제15권1호
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• pp.61-66
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• 2009

Leflunomide is an immunomodulatory agent used for the treatment of rheumatoid arthritis (RA). Leflunomide known as a regulator of iNOS synthesis which largely decreases NO production in diverse cell type. However, the effect of leflunomide on chondrocyte is still poorly understood. In our previous studies, we have shown that direct production of Nitric oxide (NO) by treating chondrocytes with NO donor, sodium nitroprusside (SNP), causes apoptosis via p38 mitogen-activated protein kinase in association with elevation of p53 protein level, caspase-3 activation. In this study, we characterized the molecular mechanism by which A77 1726 inhibit apoptosis. We found that A77 1726 inhibit NO-induced apoptosis as determined by MTT (Thiazolyl Blue Tetrazolium Bromide) assay and DNA fragmentation. The inhibition of apoptosis by A77 1726 was accompanied by increased PI-3 kinase and AKT activities. So, inhibition of phosphatidylinositol (PI)-3kinase with LY294002 rescued apoptosis. Triciribine, the specific inhibitor of AKT, also abolished anti-apoptotic effect. Our results indicate that A77 1726, the active metabolite of leflunomide, mediates NO-induced apoptosis in chondrocytes by modulating up-regulation of PI-3 kinase and AKT.

• 식물병연구
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• 제15권1호
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• pp.30-35
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• 2009

청양지역을 비롯한 멜론 연작재배지에서 매년 피해를 나타내고 있는 시들음 증상 발생주의 뿌리로부터 뿌리씩 음병 원균 Monosporascus cannonballus(28.4%), Fusarium spp.(27.4%), Didymella bryoniae(24.2%), Phytophthora spp.(20.0%) 등을 각각 분리하였다. 멜론 연작재배 토양내 뿌리썩음병 방제를 위해 고온수 관주 및 훈증제 3종 살균처리하고 방제효율을 검정하였다. 고온수($92{\sim}98^{\circ}C$) 토양관주 살균처리는 $'05{\sim}'06$년 정식전 4시간(관주량: $52{\sim}55$ tons/10a) 관주하였다. 그 결과 발병율이 0.01$\sim$0.08%로 무처리의 발병량(6.6$\sim$81.4%)보다 높은 방제효과를 나타내었다(p<0.05). 이는 토양훈증 살균제 3종의 방제효과(54.8$\sim$79.7%) 보다 20.2$\sim$45.1% 높았다. 또한, 고온수 관주처리 토양에서의 역병(Fire blight), 시들음병 (Fusarium wilt)의 발병율도 극히 낮았다 한편, 2005-2006년 고온수 관주처리구의 수량은 39톤/ha으로 무처리구(13.6톤/ha)에 비해 매우 높아 고도의 유의성을 나타내었다(P<0.05). 그러나, Dazomet, methyl bromide등 훈증제 처리는 약제 처리간 유의성은 없었으나 수량은 무처리 보다 39$\sim$47% 높았다. 결과적으로 고온수($92{\sim}98^{\circ}C$)를 이용한 연작재배지 토양 살균은 토양병해에 높은 방제효과를 나타내어 약제에 의한 훈증살균보다 효과적이라 판단되었다.

• 환경생물
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• 제41권3호
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• pp.193-203
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• 2023

에틸포메이트(Ethyl formate)는 자연상에서 발생되는 천연살충제로서 훈증방식으로 검역단계에서 해외로부터 유입되는 해충의 방제를 위하여 사용되고 있다. 특히, 메틸브로마이드의 대체제로서 주로 사용되며 인축에 독성이 약하고 식물에 대한 약해가 적다. 이러한 에틸포메이트를 농업해충방제를 훈증제로 사용하기 전에 유용생물체에 대한 독성과 수박, 애호박, 참외에 대한 식물독성 및 발생한 식물독성의 저감화 방안을 강구하고자 본 연구를 수행하였다. 에틸포메이트 2시간 훈증처리 후 지렁이, 꿀벌, 누에에 대한 LC₅₀ 값은 각각 39.9, 7.09, 17.9 g m^-3였다. EF에 대한 감수성 정도는 LC₅₀ 값 기준 지렁이, 누에, 꿀벌 순으로 낮게 나타났으며 에틸포메이트 훈증처리는 꿀벌에 대하여 강한 독성을 유발하였다. 식물독성은 7.5 g m^-3 농도로 처리된 수박 잎에서 관찰되었으며 10.0 g m^-3 농도로 처리 시 수박 잎의 가장자리는 까맣게 타들어 가는 산에 의한 약해가 발생함을 확인하였다. 다른 박과 식물인 애호박 및 참외에는 10 g m^-3 농도처리 시 잎에 강한 약해를 보였고 이를 저감하기 위하여 사용된 sodium silicate는 10% 및 20% 처리 시 약해의 저감을 확인할 수 있었다. 이와 같이 에틸포메이트 훈증처리 시 비표적생물에 대한 급성독성연구와 대상작물의 약해발생을 저감하는 연구는 에틸포메이트의 효율적인 농업해충 방제를 위한 중요한 결과를 도출했다.

• 대한화학회지
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• 제39권8호
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• pp.657-665
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• 1995

여러가지 비대칭 벤질 에테르들과 벤질 알킬 에테르들을 $CH_3CO_2Et$-NaOCI수용액(6.6 mol eq.)의 2상 용매계에서 4-methoxy-2, 2, 6, 6,-tetramethylpiperidine-1-oxyl(0.03 mol eq., 4-methoxy-TEMPO)을 이용하여 산화시키면 벤조에이트로 산화가 일어난다. 4-methoxy-TEMPO는 2차 산화제인 NaOCI에 의하여 본반응의 산화제인 N-oxo-4-2, 2, 6, 6, -tetramethyl-piperidium 염(N-oxoammonium 염)으로 변환된다. N-oxoammonium 염은 에테르를 산화시키고 N-hydroxy-4-methoxy-2, 2, 6, 6,-tetramethylpiperidine(hydroxyamine)으로 환원된다. Hydroxy-amine은 NaOCI에 의하여 N-oxoammonium 염으로 순환 재생되므로 4-methoxy-TEMPO는 촉매량 사용하였다. 이 반응은 또한 조촉매인 KBr(0.03 mol eq.)가 필수적이고 반응 중 pH는 8.0 이하로 유지되어야 한다. 0 - 5$^{\circ}C$의 반응 온도로 2.5시간 반응시키면 대부분 벤조에이트로 산화 되었다. 벤질 알킬 에테르들의 선택성 산화는 수소의 산도와 알킬기의 입체효과에 영향을 받음이 고찰되었다.

• Clinical and Experimental Pediatrics
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• 제49권6호
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• pp.593-601
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• 2006

Allergic rhinitis is a common disease of childhood characterized by nasal, throat, and ocular itching, rhinorrhea, sneezing, nasal congestion. Those affected with allergic rhinitis often suffer from associated inflammatory conditions of the mucosa, such as allergic conjunctivitis, rhinosinusitis, asthma, otitis media with effusion, and other atopic conditions, such as eczema and food allergies. Allergic rhinitis must be diagnosed and treated properly to prevent complications and impaired quality of life. Despite a high prevalence, allergic rhinitis isoften undiagnosed and inadequately treated, especially in the pediatric population. The first step in treatment is environmental control when appropriate. It may be difficult to eliminate all offending allergens effectively to reduce symptoms, so medications are often required. Many different classes of medications are now available, and they have been shown to be effective and safe in a large number of well-designed, clinical trials. Antihistamines are effective in treating immediate symptoms of sneezing, pruritus, watery eyes, and rhinorrhea. Second generation antihistamines are the preferred antihistamines because of their superior side effect profile. Thus, decongestants are commonly used with oral antihistamines. Intranasal corticosteroids are the most effective therapy for allergic rhinitis. Leukotriene modifier may be as effective as antihistamines in treating allergic rhinitis symptoms. Cromolyn sodium is an option for mild disease when used prophylactically, and ipratropium bromide is effective when rhinorrhea is the predominant symptom. When avoidance measures and medications are not effective, specific immunotherapy is an effective alternative. Only immunotherapy results in sustained changes in the immune system. Because of improved understanding of the pathogenesis, new and better therapies may be forthcoming. The effective treatment of allergic rhinitis in children will reduce symptoms and will improve overall health and quality of life, making a happier, healthier child.

• 한국환경과학회지
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• 제15권5호
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• pp.485-491
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• 2006

In the aqueous solutions the dephosphorylations of isopropyl phenyl-4-nitrophenyl phosphinate(IPNPIN) mediated by hydroxide$(OH^{\theta})$ and o-iodosobenzoate$(IB^{\theta})$ ions ate relatively slow, because of hydrophobicity of the substrate, and however it appears that $OH^{\theta}$ is inherently better nucleophile than $IB^{\theta}$, which is more soft ion. On the other hand, in cetyltrimetyiammonium bromide(CTABr) solutions which contain cationic micelles, the dephosphorylations of IPNPIN mediated by $OH^{\theta}$ or $IB^{\theta}$ ate very accelerated to 120 or 100,000 times as compared with those in the aqueous solutions. The values of pseudo first order rate constants reach a maximum with increasing. Such rate maxima are typical of micellar catalysed bimolecular reactions and the rise in rate constant followed by a gradual decrese is characteristic of reactions of hydrophobic substrates. In the cationic micellar solutions of CTABr, $IB^{\theta}$ accelerates the reactions much more than that $OH^{\theta}$ does. The reason seems that $IB^{\theta}$ which is more hydrophobic and soft ion than $OH^{\theta}$ is more easily moved into the Stern layer of the CTABr micelles than $OH^{\theta}$. In the anionic micellar solutions of sodium dodecyl sulfate(SDS), the dephosrhorylations of IPNPIN ate slower than those in aqeous solutions. It means that $OH^{\theta}$ or $IB^{\theta}$ cannot easily move and approach to the Stern layer of the micelle in which almost all the hydrophobic substrate are located and which has a negative circumstance.

• 한국축산식품학회지
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• 제24권1호
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• pp.80-85
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• 2004

본 연구에서는 역미셀을 이용한 단백질 추출공정에서 적극적으로 활용되지 못했던 양이온 계면활성제에 의한 단백질 추출 가능성을 제시하였으며 초유로부터 IgG의 분리를 위한 반응조건을 조사하였다. IgG의 분리에 적합한 조건은 반응 수용액상의 경우 pH 8, 50 mM KCl었으며 유기용매상의 계면활성제(CDAB) 농도는 100 mM로 나타났다. 위의 조건에서는 초기시료에 존재하는 IgG의 90%이상이 회수되었으며 회수된 단백질의 93%가 IgG로 나타났다. 또한 본 연구는 기존의 역미셀을 이용한 일반적인 단백질 추출공정인 정추출 및 역추출 공정을 이용하지 않고 정추출 공정만을 이용함으로써 추출과정을 단순화하였다.