• 한국연초학회지
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• 제29권2호
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• pp.125-131
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• 2007

Hydrogen cyanide(HCN), formed from pyrolysis of various nitrogenous compounds such as protein, amino acids and nitrate in tobacco, is present in both the particulate phase and vapor phase of cigarette smoke. Typically the determination of HCN in cigarette smoke has been done through colorimetric and electrochemical techniques, such as fluorescence spectrometry, UV-spectrophotometry (UV), continuous flow analyzer (CFA), capillary GC-ECD and ion chromatography (IC). Most of these techniques are known to be time-consuming and some of them lack specificity or sensitivity. The available results from both our laboratory and reported literatures for 2R4F Kentucky reference cigarette, smoked under ISO condition, show a relatively wide variation ranging from 100 to 120 ug/cig of HCN. Especially, the precision and accuracy of the analytical results of HCN tend to get worse in low tar cigarettes and under intense smoking condition. In this paper, a more optimized analytical methods than previous ones are suggested. This method shows lower detection limit and has improved precision and accuracy, so it is applicable for wide tar level cigarettes under intense smoking condition as well as under ISO smoking condition. Important features of this method are improved sample collection and quantification systems such as the number of trapping units, volume, temperature and type of trapping solution. To avoid volatilization loss of HCN in analyzing mainstream smoke, it is highly recommended that pH values of trapping solutions should be maintained over 11 and cold traps should be used in collecting mainstream smoke.

• Bulletin of the Korean Chemical Society
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• 제34권4호
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• pp.1153-1159
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• 2013

A novel solid-contact indium(III)-selective sensor based on bis-(1H-benzimidazole-5-methoxy-2-[(4-methoxy-3, 5-dimethyl-1-pyridinyl) 2-methyl]) thiosulfinate, known as an omeprazole dimer (OD) and a neutral ionophore, was constructed, and its performance characteristics were evaluated. The sensor was prepared by applying a membrane cocktail containing the ionophore to a graphite rod pre-coated with polyethylene dioxythiophene (PEDOT) conducting polymer as the ion-to-electron transducer. The membrane contained 3.6% OD, 2.3% oleic acid (OA) and 62% dioctyl phthalate (DOP) as the solvent mediator in PVC and produced a good potentiometric response to indium(III) ions with a Nernstian slope of 19.09 mV/decade. The constructed sensor possessed a linear concentration range from $3{\times}10^{-7}$ to $1{\times}10^{-2}$ M and a lower detection limit (LDL) of $1{\times}10^{-7}$ M indium(III) over a pH range of 4.0-7.0. It also displayed a fast response time and good selectivity for indium(III) over several other ions. The sensor can be used for longer than three months without any considerable divergence in potential. The sensor was utilized for direct and flow injection potentiometric (FIP) determination of indium(III) in alloys. The parameters that control the flow injection method were optimized. Indium(III) was quantitatively recovered, and the results agreed with those obtained using atomic absorption spectrophotometry, as confirmed by the f and t values. The sensor was also utilized as an indicator electrode for the potentiometric titration of fluoride in the presence of chloride, bromide, iodide and thiocyanate ions using indium(III) nitrate as the titrant.

• 한국재료학회지
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• 제23권1호
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• pp.31-34
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• 2013

Trivalent cerium-ion-doped $Y_3(Al,\;Ga)_5O_{12}$ nanoparticle phosphor nanoparticles were synthesized using the reverse micelle process. The Ce doped $Y_3(Al,\;Ga)_5O_{12}$ particles were obtained from nitrate solutions dispersed in the nanosized aqueous domains of a micro emulsion consisting of cyclohexane as the oil phase and poly(oxyethylene) nonylphenyl ether (Igepal CO-520) as the non-ionic surfactant. The crystallinity, morphology, and thermal properties of the synthesized $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ powders were characterized by thermogravimetry-differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and transmission electron microscopy. The crystallinity, morphology, and chemical states of the ions were characterized; the photo-physical properties were studied by taking absorption, excitation, and emission spectra for various concentrations of cerium. The photo physical properties of the synthesized $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ powders were studied by taking the excitation and emission spectra for various concentrations of cerium. The average particle size of the synthesized YAG powders was below $1{\mu}m$. Excitation spectra of the $Y_3Al_5O_{12}$ and $Y_3Al_{3.97}Ga_{1.03}O_{12}$ samples were 485 nm and 475 nm, respectively. The emission spectra of the $Y_3Al_5O_{12}$ and $Y_3Al_{3.97}Ga_{1.03}O_{12}$ were around 560 nm and 545 nm, respectively. $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ is a red-emitting phosphor; it has a high efficiency for operation under near UV excitation, and may be a promising candidate for photonic applications.

• 한국응용과학기술학회지
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• 제33권1호
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• pp.23-29
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• 2016

육방정계 우르자이츠형의 산화아연은 n형 반도체로써 3.37 eV의 넓은 밴드갭 에너지와 60 meV의 큰 엑시톤 바인딩 에너지를 가진 물질이다. 가스센서, 발광 다이오드, 염료 감응 태양 전지, 염료오염의 분해 등의 넓은 범위에서 활용이 가능하다. 합성 시 마이크로파 수열합성법을 사용하게 되면 높은 수율, 빠른 반응속도, 에너지 절약의 장점이 있다. 아민첨가제는 수산이온 생성 및 킬레이트 효과로 인해 산화아연 입자 형상을 조정하는 역할을 한다. 본 논문에서는 전구체로는 질산아연육수화물을 사용하였고, 형상조정제로는 에탄올아민, 에틸렌디아민, 디에틸렌트리아민, 헥사메틸렌테트라민을 사용하였다. 수산화소듐을 사용하여 용액을 pH 11로 조정하였다. 합성된 산화아연은 별모양, 막대형, 꽃모양, 원추형의 다양한 형상을 확인할 수 있었다. 아민첨가제에 의한 물리 화학적 특성과 광학적 특성을 분석하기 위해 XRD, SEM, EDS, FT-IR, UV-vis 스펙트럼, PL 스펙트럼을 사용하였다.

• 한국식품과학회지
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• 제36권2호
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• pp.361-364
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• 2004

은 이온이 불포화 지방산과의 착화합물을 만든다는 이론에 근거하여 은 이온 교환수지(SER)를 제조하였다. 제조한 SER을 비롯하여 silica gel, 질산은 함침 silica gel, 은 이온 제올라이트를 column 충전물로 사용하여 EPA와 DHA를 분리 농축하고 그 결과를 비교 분석하였다. SER과 silica gel의 9 : 1(w/w)혼합물을 충전물로 사용하였을 때 결과가 가장 좋았으며 이 경우 EPA와 DHA는 각각 27.9%와 49.1%로 농축되었고 수율은 각각 86.0%, 87.3%로 나타났다. SER만을 사용한 경우 EPA와 DHA는 각각 23.5%와 42.1%로 농축되었으며 이는 SER과 silica gel의 혼합 충전물 사용 시 보다 다소 낮은 결과이었다. 질산은 함침 silica gel의 경우 다른 충전물과 비교하여 농축율과 수율이 그다지 좋지 않았으나 EPA와 DHA의 분리 측면에서는 가장 우수한 결과를 나타내었다. SER은 재사용이 가능하고, 사용한 은 이온수지 자체도 쉽게 재생할 수 있을 뿐 아니라 사용한 은 이온도 AgCl 침전이나 $AgNO_3$로 회수가 용이하다는 점에서 다른 농축과정과 비교하여 훨씬 경제적이라 할 수 있다.

• 대한전기학회논문지
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• 제41권5호
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• pp.525-532
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• 1992

Fluorine-doped YBaS12TCuS13TOS17-xTFS1yT superconducting materials with y varing two orders of magnitude form 0.02 to 2.0 have been prepared by a sol-gel process by using metal nitrate salts, sodium hydroxide and sodium fluoride. Fluorine contents have been measured using an ion-selective electrode. All fluorine doped as reactant were found to be present in the resulted samples. From the observation of XRD it has been concluded that the samples with y 0.2 formed simply the single phase of perovskite structure, whereas those with y 0.5 yielded together some compounds such as BaFS12T, YFS13T and CuO in the resulted samples. The observation of solid state S019TF NMR has been carried out in order to check whether fluorine was actually incorporated into the lattice sites, and the experimental results revealed that the mole ratio of fluorine incorporated into the lattice sites of YBaS12TCuS13TOS17-xT was approximately 0.2 per mole of the compound. Also electrical resistivity measurement indicated that onset transition temperature has the tendency to increase slightly with increasing y in the dilute region as y 0.2.

• 한국구조물진단유지관리공학회 논문집
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• 제13권5호통권57호
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• pp.160-168
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• 2009

철근이 부식되면 오염된 콘크리트를 제거하고 철근방식을 하고 보수하는 방법과 방청제를 도포하는 방법으로는 철근위치에서 방청성능을 확보하기가 곤란한 실정이다. 이에 본 연구에서는 철근위치까지 방청제를 고압 침투시키기 위한 연구개발에 앞서 방청제 가압 침투 실험을 통하여 침투깊이를 측정하고 위치별 아질산이온의 양을 측정하여 물시멘트비, 압력, 가압시간에 따른 침투깊이 예측하고 우수한 방청성을 가지는 염화물이온과 아질산이온의 몰비 0.6 이상이 되는 물시멘트비와 압력, 가압시간을 산정하였다. 실험결과 물시멘트비가 방청제의 침투에 가장 큰 영향을 주며 또한 실험체의 깊이가 깊어질수록 침투시킨 방청제의 농도는 같지 않고 낮아지는 것을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제16권9호
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• pp.819-823
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• 1995

Thin films of two kinds of Prussian Blue (PB)-modified, using iron(Ⅲ) complex instead of conventional FeCl3, were prepared on a gold substrate and these films were able to be electrochemically reduced in potassium nitrate solution. In case of PB-modified films prepared from Fe(Ⅲ)-ethylenediamine-N,N'-diacetic acid (FeEN3+)/K3Fe(CN)6 solution, the mid-peak potential was 0.156 V in 0.1 M KNO3 and it was found that potassium ion migrates into or out of the film during the electrolysis. These films were shown to be electrochromic. These films exhibited smaller peak separation than those formed from Fe(Ⅲ)-tartaric acid (FeTA3+)/K3Fe(CN)6 system. The diffusion coefficient of Fe(CN)63-/4- redox couple, evaluated using the fabricated Au rotating disc electrode(rde) previously reported, was in good agreement with the existing data. Two experimental procedures, including the voltammetry at relatively low scan rates and the rde study, have been used in order to characterize the electrode kinetics. The electrode kinetics of some redox couples (FeEN2+-FeEN3+ and FeTA2+-FeTA3+) on both PB-modified thin films and bare Au electrode were studied using a Au rde. In all cases the rate constants of electron transfer obtained with the PB-modified film electrodes were only slightly less than those obtained for the same reaction on bare Au disc electrodes. The conductivities, as determined from the slopes of the i-V curves for a ca. 1 mm sample for dried PB-modified potassium-rich and deficient bulk samples pressed between graphite electrodes, were 6.21 × 10-7 and 2.03 × 10-7(Ω·cm)-1, respectively.

• 한국자원식물학회지
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• 제31권6호
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• pp.684-694
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• 2018

This study describes the successful establishment of a cryopreservation protocol for Citrus limon cultivars: 'Frost Eureka limon' and 'Cook Eureka limon', using a droplet-vitrification method. The shoot tips that were excised from in vitro grown seedlings of the two cultivars were preserved in liquid nitrogen (LN) and successfully regenerated into whole plants. Excised shoot tips were pre-cultured for 1 or 2 days in 0.3 M and 0.5 M sucrose solutions at $25^{\circ}C$ and incubated in a loading solution (LS) composed of 17.5% glycerol + 17.5% sucrose in Murashige and Skoog (MS) medium for 40 min at $25^{\circ}C$. Prior to direct immersion in LN for 1 h, the shoot tips were dehydrated with plant vitrification solution 2 (PVS2) at $0^{\circ}C$ or PVS3 at $25^{\circ}C$. The frozen shoot tips were re-warmed and unloaded with 1.2 M sucrose in $\text\tiny{^1/_2}$ MS for 30 min at $25^{\circ}C$. Shoot tips were post-cultured overnight on survival medium and then micrografted onto 'trifoliate orange' (Poncirus trifoliate (L.) Raf. seedling rootstocks for recovery and to produce whole plants. The highest regrowth rates were 53.5% and 50.3% for cryopreserved shoot tips of 'Frost Eureka limon' and 'Cook Eureka limon', respectively, when pre-cultured in 0.3 M and 0.5 M sucrose concentrations in a sequencing manner, with LS and treated with PVS2 for 60 min at $0^{\circ}C$. We also investigated whether the ammonium ion concentration on post-culture medium affected the viability of the cryopreserved Citrus shoot tips. The viability of cooled samples, following culturing on woody plant media (WPM) containing $\text\tiny{^1/_4}$ ammonium nitrate overnight before micrografting, was the highest (70.3%) in 'Frost Eureka limon'. The study described here is a cost-effective and safe method to conserve Citrus fruit cultivars, for the improvement and large-scale multiplication of fruit plants and for breeding disease resistance.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2207-2219
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• 2018

Activated carbon (AC) was synthesized from Phoenix dactylifera stones and then modified by $CoFe_2O_4$ magnetic nanocomposite for use as a Cr(VI) adsorbent. Both $AC/CoFe_2O_4$ composite and AC were fully characterized by FTIR, SEM, XRD, TEM, TGA, and VSM techniques. Based on the surface analyses, the addition of $CoFe_2O_4$ nanoparticles had a significant effect on the thermal stability and crystalline structure of AC. Factors affecting chromium removal efficiency like pH, dosage, contact time, temperature, and initial Cr(VI) concentration were investigated. The best pH was found 2 and 3 for Cr adsorption by AC and $AC/CoFe_2O_4$ composite, respectively. The presence of ion sulfate had a greater effect on the chromium sorption efficiency than nitrate and chlorine ions. The results illustrated that both adsorbents can be used up to seven times to adsorb chromium. The adsorption process was examined by three isothermal models, and Freundlich was chosen as the best one. The experimental data were well fitted by pseudo-second-order kinetic model. The half-life ($t_{1/2}$) of hexavalent chromium using AC and $AC/CoFe_2O_4$ magnetic composite was obtained as 5.18 min and 1.52 min, respectively. Cr(VI) adsorption by AC and $AC/CoFe_2O_4$ magnetic composite was spontaneous and exothermic. In general, our study showed that the composition of $CoFe_2O_4$ magnetic nanoparticles with AC can increase the adsorption capacity of AC from 36 mg/L to 70 mg/L.