• 콘크리트학회논문집
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• 제17권1호
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• pp.105-112
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• 2005

트럭믹서 및 배쳐 플랜트 세척으로 발생되는 회수수를 안정화시켜 재이용하는 것은 콘크리트의 품질 불안정을 해소하고 강도 향상의 효과를 기대할 수 있기 때문에 이의 활용방안에 대한 적극적인 검토가 요구된다. 본 연구에서는 우리나라의 레미콘 생산 조건에서 사용 가능한 안정화제의 종류를 도출하고자 이를 사용한 회수수 중의 고형분 성상에 대하여 실험?고찰하였다. 실험결과, 회수수 전용 안정화제인 옥시칼본산계 지연제의 고형분량 감소가 상대적으로 우세하였다. 다만, 잉여 반응량에 의해 시멘트 페이스트의 응결지연이 관찰되었으나 레미콘 적용상 저해되는 수준은 아니었다. 안정화제를 혼입한 회수수를 방치함에 따른 영향에서는 초기의 응결지연 효과가 7${\~}$8일 정도에서 상수도수만을 사용한 수준으로 회복됨을 알 수 있었으며, 2${\~}$3일 정도에 안정화 회수수를 사용하는 것이 효과적임을 확인할 수 있었다. 한편, 국내산 당류계 초지연제 역시 유사한 효과를 보여 적용성이 높은 것으로 파악되었다. 시판되는 회수수 안정화제는 수입에 의존하고 있으므로 사회비용의 절감을 위해 안정화제의 국산화가 시급하며 가능한 안정화제의 다각적인 사용성 검토가 긴요하다 할 것이다.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.1972-1984
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• 2013

Microtubules play an important role in intracellular transport, mobility, and particularly mitosis. Paclitaxel (Taxol$^{TM}$) and paclitaxel-like compounds have been shown to be anti-tumor agents useful for various human tumors. Paclitaxel-like compounds operate by stabilizing microtubules through interface binding at the interface between two ${\beta}$-tubulin monomers in adjacent protofilaments. In this paper we present the elucidation of the structural features of paclitaxel and paclitaxel-like compounds (e.g., epothilones) with microtubule stabilizing activities, and relate their activities to spatial and chemical features of the molecules. CATALYST program was used to generate three-dimensional quantitative structure activity relationships (3D-QSARs) resulting in 3D pharmacophore models of epothilone- and paclitaxel-derivatives. Pharmacophore models were generated from diverse conformers of these compounds resulting in a high correlation between experimental and predicted biological activities (r = 0.83 and 0.91 for epothilone and paclitaxel derivatives, respectively). On the basis of biological activities of the training sets, five- and four-feature pharmacophore hypotheses were generated in the epothilone and paclitaxel series. The validation of generated hypotheses was achieved by using twelve epothilones and ten paclitaxels, respectively, which are not in the training sets. The clustering (grouping) and merging techniques were used in order to supplement spatial restrictions of each of hypothesis and to develop more comprehensive models. This approach may be of use in developing novel inhibitor candidates as well as contributing a better understanding of structural characters of many compounds useful as anticancer agents targeting microtubules.

• Macromolecular Research
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• 제13권3호
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• pp.236-242
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• 2005

Three dithioester-derived carboxyl acid functionalized RAFT(reversible addition-fragmentation chain transfer) agents, viz. acetic acid dithiobenzoate, butanoic acid dithiobenzoate and 4-toluic acid dithiobenzoate, were used in the RAFT bulk polymerization of styrene, in order to study the effects of the R-group structure on the living nature of the polymerization. By conducting the polymerization with various concentrations of the RAFT agents and at different temperatures, it was found that the R-group structure of the RAFT agents plays an important role in the RAFT polymerization; the bulky structure and radical stabilizing property of the R-group enhances the living nature of the polymerization and allows the polymerization characteristics to be well controlled.

• 한국재료학회지
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• 제22권9호
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• pp.465-469
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• 2012

This paper focuses on the after synthesis of CdTe quantum dots(QDs) in aqueous solution. CdTe nanoparticles were prepared in aqueous solution using mercaptocarboxylic acid or thioglycolic acid(TGA) as stabilizing agents. QDs emit light smaller than the nano size. The contents of the mercaptocarboxylic acid, and a kind of raw material, were revealed for a period of time. We succeeded in synthesizing a very high quality QDs solution; we discussed how to make QDs better and to keep them stabilized. TGA is known as one of the best stabilizing agents. Many papers have mentioned that TGA is a good stabilizing agent. We dramatically confirmed the state of QDs after the experiments. The QDs solution can be influenced by several factors. Different content of TGA can influence the stability of the CdTe solution. Most papers deal with the synthesis of CdTe, so we decided to discuss the after synthesis process for the stability of the CdTe solution.

• The Korean Journal of Ecology
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• 제24권2호
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• pp.121-123
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• 2001

Gums, resins and gum-resins represent a variety of plant exudates that are highly prized and are extensively used in various industries. The usage of water soluble gums is growing at faster rate as they are excellent suspending agents, dispersants stabilizing agents, emulsifiers and gel forming agents. The gums are made up of carbohydrate polymers, composed of sugar units glycosidically condensed to form large molecules. Resins are non-volatile products, and oxidative products of terpenes or fatty acids, and are of greater commercial importance. They are soluble in water and contrasted with gums, soluble in organic solvents only.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권6호
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• pp.1-11
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• 2017

This study was conducted to investigate the performance of four commercial chemical agents in stabilizing arsenic (As) in soil at the forest area near the former Janghang smelter site. After amending the stabilizing agents (A, B, C, and D) into As-contaminated soil samples, synthetic precipitation leaching procedure (SPLP) and solubility bioavailability research consortium (SBRC)-extractable As concentrations significantly decreased except for agent D, which is mainly composed of fly ash and calcium carbonate. Increase of SPLP and SBRC-extractable As concentrations in four soil samples (S1, S2, S3, and J2) was attributed to desorption of As adsorbed on iron oxides due to high pH generated by agent D. It is therefore necessary to consider application conditions according to soil characteristics such as pH and buffering capacity. Results of sequential extraction showed that readily extractable fractions of As in soil (i.e., sum of $SO_4-$ and $PO_4-extractable$ As in soil) were converted into non-readily extractable fractions by amending agents A, B, and C. Such changes in the As distribution in soil resulted in the decrease of SPLP and SBRC-extractable As concentration. A series of follow-up monitoring and management plan has been suggested to assess the longevity of the stabilization treatments in the site.

• The Korean Journal of Physiology and Pharmacology
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• 제17권3호
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• pp.197-201
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• 2013

The purpose of this study was to examine the anti-oxidative activity of pectin and other polysaccharides in order to develop a cosmeceutical base having anti-oxidative effects towards retinyl palmitate (RP). The anti-oxidative stabilizing effects of pectin and other polysaccharides on RP were evaluated by DPPH assay and then the stabilizing effect of pectin on RP was examined as a function of time. Among the polysaccharides we examined, pectin exhibited a considerably higher anti-oxidative activity, with an approximately 5-fold greater DPPH radical scavenging effect compared to other polysaccharides. The DPPH radical scavenging effect of pectin increased gradually with increasing concentrations of pectin. At two different RP concentrations, 0.01 and 0.1% in ethanol, addition of pectin improved the stability of RP in a concentration dependent manner. The stabilizing effect of pectin on RP was more effective for the lower concentration of RP (0.01%, v/v). Further, degradation of RP was reduced following the addition of pectin as measured over 8 hours. From the results obtained, it can be suggested that pectin may be a promising ingredient for cosmeceutical bases designed to stabilize RP or other pharmacological agents subject to degradation by oxidation.

• 한국지하수토양환경학회지:지하수토양환경
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• 제14권4호
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• pp.45-53
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• 2009

본 연구는 안정화제를 이용한 윈위치 화학적 고정(In-situ Chemical fixation) 방법으로 휴, 폐광산 주변 중금속 오염농경지 정화 방법의 적용성을 자연상태에 보다 근접한 컬럼시험을 통해 평가하였다. 특히 특정원소가 아닌 다원소로 오염된 토양을 대상으로, 두가지 이상의 안정화제 조합을 시도하여 최적 비율을 산정하였다. 컬럼시험에 사용된 안정화제들은 $FeSO_4\;+\;KMnO_4$, $CaCO_3$, 영가철, 슬러지(탄광폐수처리소택지 발생) 및 지올라이트 등이었으며 비소가 주 오염원인 경북 달성 지역 소재 광산에서 밭토양을 채취하여 시험한 결과 비소의 경우 $FeSO_4\;+\;KMnO_4$, > 지올라이트 등의 순서로 좋은 효율을 보였으며 구리의 경우 영가철과 슬러지가 안정화 효율을 보였다. 황화철 혼합제재의 경우 대부분의 중금속들에 대해 가장 좋은 효율을 보임에도 용출 초기 pH 4정도의 산성으로 인해 중금속이 다량 용출되므로 pH를 조정하거나 전처리를 거칠 경우 안정화 효율이 증가할 것으로 판단된다. 컬럼은 시험 시작에 앞서 증류수로 72시간 이상 포화한 것과 사전에 포화과정 없이 바로 물을 흘려 넣은 두 조합을 동시에 운영하였으며 전자가 더 좋은 효율을 나타낸다.

• 보존과학회지
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• 제8권1호
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• pp.28-32
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• 1999

비교적 치수안정화 처리가 어려운 참나무과 고목재를 선택하여 락티톨, PEG (Mw, 4000), 슈크로오스를 이용하여 치수안정화효과에 대한 비교실험을 하였다. 시료 제작은 접선단면 판재 형태의 유물에서 굽음, 뒤틀림 등의 변형이 발생할 우려가 특히 크므로 접선단면이 넓게 나오도록 제작하였다. 보존처리약제의 처리농도는 10, 30, 50, $70\%$로 상승시켰고 각 농도단계별로 3일간, 7일간씩 처리하여 중량증가율을 측정하였다. 처리가 종료된 후의 시험편의 치수안정화효과를 평가하기 위한 지표로써 횡단면수축율을 산출하였다. 그 결과 슈크로오스를 함침처리한 시험편은 중량 증가율이 가장 높았으며, 횡단면수축율도 3일, 7일 처리에서 각각 $7\%,\;4\%$로 가장 높은 치수안정화효과를 나타내었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권4호
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• pp.1-8
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• 2012

The success of stabilization treatment in heavy metal contaminated sediment depends on the heavy metal bioavailability reduction through the sequestration of the heavy metals. This study was performed to assess the changes in the bioavailability of Pb or Cd in the Pb or Cd contaminated sediments by using birnessite and hydroxyapatite as stabilizing agents. The toxicity tests were carried out using a microorganism (Vibrio fischeri), an amphipod (Hyalella azteca) and an earthworm (Eisenia foetida). With Vibrio fischeri, the toxicities of both Pb and Cd were reduced by more than ten times in the presence of birnessite and hydroxyapatite compared to that of in the absence of birnessite and hydroxyapatite. The concentrations of Pb and Cd in the contaminated sediments were lethal to Hyalella azteca, however, in the presence of birnessite and hydroxyapatite more than 90%, on average, of Hyalella azteca survived. With Eisenia foetida, the bioaccumulated concentrations of both Pb and Cd were reduced by more than 75%, on average, lower with the addition of birnessite and hydroxyapatite to the contaminated sediments. These results show that the addition of birnessite and hydroxyapatite can reduce the bioavailability of Pb and Cd in contaminated sediments. In addition, the in situ and ex situ performance of birnessite and hydroxyapatite as stabilizing agents can be verified using the toxicity tests with Hyalella azteca and Eisenia foetida, respectively.