• 한국의류학회지
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• 제41권3호
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• pp.517-526
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• 2017

The biodegradation and water absorption properties of lignin/poly(vinyl alcohol) (PVA) nanofibrous webs are investigated. Lignin/PVA nanofibrous webs containing 0, 50, and 85wt% of lignin were prepared via an electrospinning process to observe the effect of the lignin concentration on the biodegradability and water absorption properties of lignin/PVA nanofibrous webs. The morphology of the materials was examined by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). To understand the wetting behavior and hydrophilic nature of the electrospun lignin/PVA nanofibrous webs, the water absorbency, contact angle, and water uptake were examined. The enzymatic degradation of lignin/PVA nanofibrous webs was investigated using laccase by measuring total organic carbon (TOC) concentration over a course of 50 days. Water drops were absorbed immediately into all of the specimens. The water uptake of lignin/PVA nanofibrous webs increased as the amount of PVA in the lignin/PVA hybrid webs increased. The enzymatic degradation experiment indicated that the inherent biodegradability of lignin was retained after its transformation into nanofibers. Our findings imply that blending these two types of polymers is promising because it can lead to the development of a new range of multifunctional materials such as antimicrobial absorbent nanotextiles based on sustainable biopolymers.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.337-337
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• 2011

The elecronic absorption and surface morphology evolution of two types of molecular double layer thin films, copper phthalocyanine(CuPc) layer deposited on top of chloro[subphtalocyaninato]boron(III) (SubPc) layer, denoted as SubPc/CuPc, and vice versa, at various thicknesses were invertigated using ultraviolet(UV)-visible spectroscopy and atomic force microscopy (AFM). Both types of double layer structures showed similar broadened absorption patterns in UV-visible region which were well consistent with fitted spectra by a simple linear combination of single layer absorption spectra of two materials. In contrast, the surface morphology of double layer structures was dependent on the order of deposition. For CuPc/SubPc structures, the surface morphology was characterized by elongated grains, characteristic of SubPc thin films, indicating the morphological influence of underlying CuPc layer on subsequent SubPc layer was not large. For SubPc/CuPc structures, however, the underlying SubPc layer acted as a morphological template for the subsequently deposited CuPc layer. It was also observed that the grain size of CuPc layer varied by the thickness of underlying SubPc layer.

• 천문학논총
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• 제30권2호
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• pp.75-78
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• 2015

A growing body of evidence has been supporting the existence of so-called "dark molecular gas" (DMG), which is invisible in the most common tracer of molecular gas, i.e., CO rotational emission. DMG is believed to be the main gas component of the intermediate extinction region from Av~0.05-2, roughly corresponding to the self-shielding threshold of $H_2$ and $^{13}CO$. To quantify DMG relative to $H{\small{I}}$ and CO, we are pursuing three observational techniques; $H{\small{I}}$ self-absorption, OH absorption, and THz $C^+$ emission. In this paper, we focus on preliminary results from a CO and OH absorption survey of DMG candidates. Our analysis shows that the OH excitation temperature is close to that of the Galactic continuum background and that OH is a good DMG tracer co-existing with molecular hydrogen in regions without CO. Through systematic "absorption mapping" by the Square Kilometer Array (SKA) and ALMA, we will have unprecedented, comprehensive knowledge of the ISM components including DMG in terms of their temperature and density, which will impact our understanding of galaxy evolution and star formation profoundly.

• 천문학회보
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• 제44권1호
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• pp.42.3-42.3
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• 2019

The high-resolution near-infrared (NIR) spectroscopy can reveal the evidence of the accretion burst (e.g., the broadened absorption features produced by the Keplerian disk motion) although the moment of the outburst was not caught. The embedded protostar IRAS 16316-1540 observed with the Immersion Grating Infrared Spectrograph (IGRINS, $R={\Delta}{\lambda}/{\lambda}{\sim}45000$) shows the broad absorption features in atomic and CO transitions, as seen in FU Orionis objects (FUors), indicative of an outburst event. We examine whether the spectra of IRAS 16316-1540 arise from the rotating inner hot gaseous disk. Using the IGRINS spectral library, we show that the line profiles of IRAS 16316-1540 are more consistent with an M1.5 V template spectrum convolved with a disk rotation profile than the protostellar photosphere absorption features with a high stellar rotation velocity. We also note that the absorption features deviated from the expected line profile of the accretion disk model can be explained by a turbulence motion generated in the disk atmosphere. From previous observations that show the complex environment and the misaligned outflow axes in IRAS 16316-1540, we suggest that an impact of infalling clumpy envelope material against the disk induces the disk precession, causing the accretion burst from the inner disk to the protostar.

• Journal of Nutrition and Health
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• 제33권7호
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• pp.717-724
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• 2000

A number of epidemiological studies has indicated lifestyles including dietary habits are closely related to the development of certain forms of cancer. These findings have led several investigators to identify the ways in which these factors mdulate the risk of cancer. Seaweeds are rich sources of non-digestible polysaccharides which possibly posses physiological functions. In vitro studies showed several components in seaweeds inhibit tumor cell growth and mutagenicity of known food mutagens. On the other hand non-digestible polysaccharides of different food sources negatively affect mineral nutrition by decreasing mineral absorption. The objectives of this study was to investigate the effect of major seaweed intake on azoxymethane(AOM) - induced DNA damage a known cancer initiation step and on apparent absorption of calcium and iron. To accomplish these objectives twenty five ICR mice were divided into five groups and fed one of the following diets for 10 days : control diet d, diet containing 10% water-soluble fraction of seamustard or seatangle diet containing 10% water-insoluble fraction of seamustard or seatangle. AOM was injected 6 hours before sacrifice and N7-methylated guanines from the colonic DNA were quantified using a gas chromatography -mass spectroscopy. Fecal samples were collected on days 4 and 8. Caclium and iron contents of the diets and feces were analyzed using an atomic absorption spectrophotometry to determine the apparent absorption of these minerals. Results are as follows. AOM-induced guanine methylation of colon was decreased in animals fed diets containing water-soluble fractions of seamustard or seatangle compared to those in animals fed control diet although only the seatnagle fed group showed statistically significant effect. Apparent calcium absorption was significantly reduced in animals fed diets containing water-insoluble fractions of seaweeds. Iron absorption was significantly decreased and negatively balanced in animals fed diets containing water-insoluble fractions of both seaweeds, and water-soluble fraction of seatangle. In conclusion, seamustard and seatangle intakes may effectively prevent colon tumorigenesis by reducing a carcinogen-induced DNA damages, and more mechanistic studies on possible role of seaweeds on carcinogenesis are required. Also, adverse effects of seaweed diets cintaming a large amount of polysaccharides on mineral nutrition should be carefully monitored.

• 대한화학회지
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• 제29권2호
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• pp.129-136
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• 1985

공기-아세틸렌 불꽃 원자 흡수분광법으로 칼슘분석을 하는 경우 비교적 방해가 큰 것은 지르코늄, 주석, 알루미늄, 안티몬 등 양이온과 황산이온, 바나듐산이온, 규산이온 등 음이온이다. 여기에 해방제로서 세륨을 사용하면 이들 방해 효과를 제거할 수 있음을 알게 되었다. 칼슘과 같은 농도($3.0 {\times} 10^{-4}$M)의 이 방해이온들에 의한 방해는 방해이온 농도의 2배의 세륨에 의하여 완전히 해방됨을 보았고 방해 양이온혼합물(지르코늄, 주석, 알루미늄, 안티몬), 방해음이온 혼합물(황산이온, 바나듐산이온, 규산이온)또는 방해양이온 음이온 혼합물의 방해는 각각의 양이온 혹은 음이온에 의한 방해보다 더 큰 방해를 주는데 세륨($1.5 {\times} 10^{-2}$M)에 의한 해방효과는 방해양이온, 음이온 혼합물의 농도가 각각 $3.0 {\times} 10^{-3}$M까지 증가하여도 거의 변하지 않고 좋았다.

• 한국산업보건학회지
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• 제11권1호
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• pp.48-55
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• 2001

The purpose of this study was to evaluate the analytical accuracy and precision of microwave oven digestion/atomi absorption spectrophotometry (AAS) for analyzing airborne chromium collected on mixed cellulose ester membrane (M filter from the work environment, and to compare the accuracy and the precision with those of the National Institute for Occupational Safety and Health (NIOSH) Method #7024 hot plate digestion/AAS method. For this study, field air sample pairs were collected from a electroplating process, and spiked samples in a laboratory were prepared and using these samples. Two digestion methods were comp; and evaluated in terms of recovery rate and bias as indices of accuracy and coefficient of variation as a index of precision. The results and conclusions are as follows. In spiked samples, the accuracies (% mean recoveries) of hot plate/AAS and microwave oven/AAS method were 97.19%, 97.1%, respectively, and the precisions (pooled respectively, and the precisions (pooled coefficient of variance, $CV_{pooled}$) 6.93% and 3.88%, respectively. The biases of hot plate ani microwave oven methods were 4.56 - 14.7% and 2.22 - 7.42% respectively. There was no statistically significant difference between hot plate and microwave oven methods recovery rates of spiked samples (p>0,05). Also, no statistically significant difference was shown among the concentrations of air samples determined by two method (p>0.05). In conclusion, microwave oven/AAS method h excellent accuracy and precision, and advantages such as time-saving and simple procedure in comparison with the classical NIOSH method. Therefore, this method can be use widely to analyze airborne chromium collected on MCE filter from the work environments.

• 한국진공학회지
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• 제20권4호
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• pp.252-257
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• 2011

본 연구 그룹은 6H-SiC (0001)에서 성장시킨 그라핀 층에 흡착된 퓨란(furan)의 고리 형성과 전자적 성질을 원자 힘 현미경(Atomic Force Microscope : AFM), C K-edge에 대한 Near Edge X-ray Absorption Fine Structure (NEXAFS) 스펙트럼, 핵심부 준위 광전자 분광스펙트럼(Core-level Photoemission Spectroscopy : CLPES)을 이용하여 연구했다. 우리는 그라핀위에 흡착된 퓨란 분자들이 화학적 도핑이 가능한 산소기의 홀 전자쌍을 통하여 그라핀의 특성을 조절할 수 있는 화학적 기능화에 이용될 수 있다는 것을 알아냈다. 또한, 퓨란이 자발적으로 세 가지의 다른 결합 구조들 중 하나로 고리를 형성한다는 것과 그라핀 위에 퓨란에 의해 형성된 고리의 전자적 성질들이 AFM, NEXAFS, CLPES를 이용하여 각각 설명될 수 있다는 것을 보여주었다.

• 대한화학회지
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• 제36권2호
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• pp.273-281
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• 1992

원자흡수분광법을 위한 글로우방전 분광 장치를 sputtering된 시료원자가 기저상태의 원자가 최대이며 여기 상태의 원자가 최소가 되는 지역을 측정하도록 설계 개발하였다. 빠른 속도의 가스 jet는 방전의 육안 및 전기적 변화 뿐만 아니라 시료표면의 변화에서 처럼 시료가 원자화되는 양을 현저히 증가시킨다. 가스 jet는 원자흡수분광법으로 시료를 직접할 수 있는 가능성을 보여주었다. 감도와 재현성에 영향을 끼치는 여러 가지 요인들에 관하여 연구하였다.

• Journal of Electrochemical Science and Technology
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• 제1권1호
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• pp.31-38
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• 2010

In this study, we have demonstrated the fine structure effect of PdCo electrocatalyst on oxygen reduction reaction activity with different alloy composition and heat-treatment time. In order to identify the intrinsic factors for the electrocatalytic activity, various X-ray analyses were used, including inductively coupled plasma-atomic emission spectrometer, transmission electron microscopy, X-ray diffractometer, and X-ray Absorption Spectroscopy technique. In particular, extended X-ray absorption fine structure was employed to extract the structural parameters required for understanding the atomic distribution and alloying extent, and to identify the corresponding simulated structures by using FEFF8 code and IFEFFIT software. The electrocatalytic activity of PdCo alloy nanoparticles for the oxygen reduction reaction was evaluated by using rotating disk electrode technique and correlated to the change in structural parameters. We have found that Pd-rich surface was formed on the Co core with increasing heating time over 5 hours. Such core shell structure of PdCo/C showed that a superior oxygen reduction reaction activity than pure Pd/C or alloy phase of PdCo/C electrocatalysts, because the adsorption energy of adsorbates was apparently reduced by lowering the dband center of the Pd skin due to a combination of the compressive strain effect and ligand effect.