• Macromolecular Research
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• 제14권2호
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• pp.199-204
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• 2006

Remarkably high and stable separation performance for olefin/paraffin mixtures was previously reported by facilitated olefin transport through ${\pi}$-complex membranes consisting of silver ions dissolved in poly(hexamethylenevinylene) (PHMV). In this study, the ${\pi}$-complex formation of $AgBF_4,\;AgClO_4\;and\;AgCF_{3}SO_3$ with PHMV and their ionic interactions were investigated. FT-Raman spectroscopy showed that the C=C stretching bands of PHMV shifted to a lower frequency upon incorporation of silver salt, but the degree of peak shift depended on the counter-anions of salt due to different complexation strengths. The symmetric stretching modes of anions indicated the presence of only free ions up to [C=C]:[Ag]=1:1, demonstrating the unusually high solubility of silver salt in PHMV. Above the solubility limit, the ion pairs and higher-order ionic aggregates started to form. The coordination number of silver ion for C=C of PHMV was in the order $AgBF_4$ > $AgClO_4$ > $AgCF_{3}SO_3$, but became similar at [C=C]:[Ag]=1:1. The different coordination number was interpreted in terms of the different transient crosslinks of silver cations in the complex, which may be related to both the interaction strength of the polymer/silver ion and the bulkiness of the counteranion.

• 상하수도학회지
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• 제30권3호
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• pp.263-270
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• 2016

Recent Engineered nanoparticles were increasingly exposed to environmental system with the wide application and production of nanomaterials, concerns are increasing about their environmental risk to soil and groundwater system. In order to assess the transport behavior of silver nanoparticles (AgNPs), a saturated packed column experiments were examined. Inductively coupled plasma-mass spectrometry and a DLS detector was used for concentration and size measurement of AgNPs. The column experiment results showed that solution chemistry had a considerable temporal deposition of AgNPs on the porous media of solid glass beads. In column experiment, comparable mobility improvement of AgNPs were observed by changing solution chemistry conditions from salts (in both NaCl and $CaCl_2$ solutions) to DI conditions, but in much lower ionic strength (IS) with $CaCl_2$. Additionally, the fitted parameters with two-site kinetic attachment model form the experimental breakthrough curves (BTCs) were associated that the retention rates of the AgNPs aggregates were enhanced with increasing IS under both NaCl and $CaCl_2$ solutions.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2918-2922
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• 2010

We demonstrate a facile route to synthesize silver chloride nanocubes and derivative nanomaterials. For the synthesis of silver chloride nanocubes, silver nitrate and hydrochloric acid were used as precursors in ethylene glycol, and poly (vinyl pyrrolidone) as a surfactant. Molar ratio of the two precursors greatly influenced the morphology and composition of the final products. As-synthesized silver chloride nanocubes showed size-dependent optical properties in the visible region of light, which is likely due to a small amount of silver clusters formed on the surface of silver chloride nanocubes. Moreover, we show for the first time that simple reduction of silver chloride nanocubes with different reducing reagents leads to the formation of delicate nanostructures such as cube-shaped silver-nanoparticle aggregates, and silver chloride nanocubes with truncated corners and with silver-nanograin decorated corners. Additionally, we quantitatively investigated for the first time the evolution of silver chloride nanocubes to silver chloride nanocubes decorated with silver nanoparticles upon exposure to e-beam. Our novel and facile synthesis of silver chloride related nanoparticles with delicately controlled morphologies could be an important basis for fabricating efficient photocatalysts and antibacterial materials.

• Carbon letters
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• 제2권3_4호
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• pp.159-164
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• 2001

In this study, the effects of carbon black (CB) content and anodic oxidation treatment with $AgNO_3$ on positive temperature coefficient (PTC) behavior of CB/HDPE nanocomposites were investigated. Also, the addition of elastomer as a toughing agent was studied. The 20~50 wt% of CB, 0~5 wtt% of elastomer, and 1 wt% of $AgNO_3$-filled HDPE nanocomposites were prepared using the internal mixer in 60 rpm at $160{\circ}C$ and the compression-molded at $180{\circ}C$ for 10 min. As a result, the room temperature resistivity and PTC intensity of the composites were dependent, to a large extent, on the content of CB, addition of elastomer, and surface chemical properties that were controlled in the relative arrangements of the carbon black aggregates in a polymeric matrix. Moreover, the composites with relatively low room temperature resistivity and suitable PTC intensity could be achieved by treatment of $AgNO_3$. Consequently, it was noted that PTC effect was due to the deagglomeration or the breakage of the conductive networks caused by thermal expansion or crystalline melting of the polymeric matrix.

• 대한약침학회지
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• 제25권4호
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• pp.326-343
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• 2022

Neurological disorders represent a substantial healthcare burden worldwide due to population aging. Acorus gramineus Solander (AG) and Acorus tatarinowii Schott (AT), whose major component is asarone, have been shown to be effective in neurological disorders. This review summarized current information from preclinical and clinical studies regarding the effects of extracts and active components of AG and AT (e.g., α-asarone and β-asarone) on neurological disorders and biomedical targets, as well as the mechanisms involved. Databases, including PubMed, Embase, and RISS, were searched using the following keywords: asarone, AG, AT, and neurological disorders, including Alzheimer's disease, Parkinson's disease, depression and anxiety, epilepsy, and stroke. Meta-analyses and reviews were excluded. A total of 873 studies were collected. A total of 89 studies were selected after eliminating studies that did not meet the inclusion criteria. Research on neurological disorders widely reported that extracts or active components of AG and AT showed therapeutic efficacy in treating neurological disorders. These components also possessed a wide array of neuroprotective effects, including reduction of pathogenic protein aggregates, antiapoptotic activity, modulation of autophagy, anti-inflammatory and antioxidant activities, regulation of neurotransmitters, activation of neurogenesis, and stimulation of neurotrophic factors. Most of the included studies were preclinical studies that used in vitro and in vivo models, and only a few clinical studies have been performed. Therefore, this review summarizes the current knowledge on AG and AT therapeutic effects as a basis for further clinical studies, and clinical trials are required before these findings can be applied to human neurological disorders.

• Macromolecular Research
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• 제16권8호
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• pp.676-681
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• 2008

The $\pi$-complex membranes of poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) of two silver salts of $AgBF_4$ and $AgCF_3SO_3$ were prepared and tested for the separation of the propylene/propane mixtures. The Fourier-transform infrared (FT-IR) spectra of these complexes showed that the silver salts were dissolved in SEBS up to a silver mole fraction of 0.14, due to $\pi$-complexation between the aromatic C=C bonds of styrene blocks and silver ions. Above this solubility limit, ion pairs and high-order ionic aggregates began to form, so that silver salts were distributed unselectively in both the EB and PS blocks. The domain size of the PS blocks was enlarged up to this critical concentration with increasing silver concentration without structural transitions, as confirmed by small angle x-ray scattering (SAXS). These structural properties of the SEBS/silver salt complexes may explain the lower separation properties for propylene/propane mixtures compared to poly(styrene-b-butadiene-b-styrene)(SBS)/silver salt complex membranes.

• 한국건축시공학회지
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• 제15권2호
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• pp.161-167
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• 2015

최근, 전 세계적으로는 지구온난화 등 환경문제의 심각성을 인식하여 이산화탄소의 배출량을 줄이는 노력을 경주하고 있다. 이와 관련하여 선행 연구에서는 산업부산물인 RA의 알칼리로 BS의 잠재 수경성 반응을 자극시켜, 무시멘트 조건에서 알칼리 활성(Alkali activation)화 시키는 새로운 메커니즘으로 강도 발현성을 확인 바 있다. 본 연구는 제조과정에 따른 석고의 종류 및 소각장에서 발생한 WA 등을 자극제 용도로 추가하여 강도등 품질에 미치는 영향에 대해 검토를 진행하였다. 그 결과, BS에 RA를 사용하는 무 시멘트 모르타르에 WA 0.5%와 AG 20%를 사용할 경우 초기강도는 낮을 지라도 91일강도는 OPC강도이상으로 발휘 되어 양호한 결과를 얻을 수 있었다.

• 마이크로전자및패키징학회지
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• 제21권4호
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• pp.133-137
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• 2014

직경 수 마이크론급의 Ag 코팅 Cu 플레이크를 제조하기 위한 선행공정으로 습식 화학적 합성법으로 제조된 서브마이크론급의 Cu 입자를 볼 밀링 공정을 통해 프레이크화 하였다. 입자들의 산화 및 응집을 막기 위해 볼 밀링 유체로는 에틸렌글리콜을 사용하였고, 에틸아세테이트 표면개질제도 첨가하였다. 용기의 회전수에 따른 실험 결과를 통해 회전수에 따른 회전 모드의 변화가 밀링 후 Cu 입자들의 평균적인 형상과 형상 균일도를 크게 변화시킴을 확인할 수 있었다. 또한 첨가한 지르코니아 볼의 직경 역시 Cu 입자들의 플레이크화 균일도를 결정하는 대표 공정변수임을 확인할 수 있었다. 그 결과 다소간의 응집체를 포함한 서브마이크론급의 Cu 입자를 사용했음에도 불구하고, 회전수, 표면개질제 첨가량, 그리고 지르코니아 볼의 직경 등의 대표 공정변수들을 최적화한 볼 밀링 공정을 통해 분산성이 우수한 수 마이크론급의 Cu 플레이크를 성공적으로 제조할 수 있었다.

• Macromolecular Research
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• 제15권4호
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• pp.343-347
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• 2007

Novel composite membranes, which delivered high separation performance for propylene/propane mixtures, were developed by coating inert poly(ethylene-co-propylene) rubber (EPR) onto a porous polyester substrate, followed by the physical distribution of $AgBF_4$. Scanning electron microscopy-wavelength dispersive spectrometer (SEM-WDS) revealed that silver salts were uniformly distributed in the EPR layer. The physical dispersion of the silver salts in the inert polymer matrix, without specific interaction, was characterized by FT-IR and FT-Raman spectroscopy. The high separation performance was presumed to stem from the in-situ dissolution of crystalline silver ionic aggregates into free silver ions, which acted as an active propylene carrier within a propylene environment, leading to facilitated propylene transport through the membranes. The membranes were functional at all silver loading levels, exhibiting an unusually low threshold carrier concentration (less than 0.06 of silver weight fraction). The separation properties of these membranes, i.e. the mixed gas selectivity of propylene/propane ${\sim}55$ and mixed gas permeance ${\sim}7$ GPU, were stable for several days.

• 한국농공학회지
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• 제37권1호
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• pp.73-80
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• 1995

This study was carried out to investigate the engineering properties of no-fines con- crete, consisting only of coarse aggregate, cement and water. The used coarse aggregates were two, one is natural coarse aggregate grading 4.75~ lOmm, the other is synthetic lightweight coarse aggregate grading 3~8mm. The results of this study are summarized as follows; 1. The W/C ratio of each type was increased with increase of additional amount of coarse aggregate. 2. The unit weight of used ndtural coarse aggregate was shown 1.762~2.184g/cm$^3$, and synthetic lightweight coarse aggregate was shown 0.756 ~ 1 .348g/cm$^3$. 3. The ahsorption rate of used natural coarse aggregate was shown 8.4 ~ 9.4 %, and synthetic lightweight coarse aggregate was shown 17.0~42.4%. 4. The compressive, tensile and hending strength was decreased with increase of coarse aggregate, respectively. The compressive strength of natural coarse aggregate 1:3 was shown 309kg/cm$^2$. 5. The ultrasonic pulse velocity and dynamic medulus of elasticity of each type was de- creased with increase coarse aggregate, respectively. Also, the decreasing rate of the natural aggregate was larger than that of the synthetic lightweight coarse ag- gregate.