• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.412-420
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• 2023

In this study, red mud/fly ash based geopolymer adsorbents (RFGPA) were prepared with calcination temperatures of 200, 400, and 600 ℃, and the effects of these calcination temperatures on the adsorption of methylene blue (MB) were investigated. In addition, the prepared RFGPA was characterized using X-ray fluorescence (XRF), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) spectroscopy, and Brunauer-EmmettTeller (BET) analysis. The results of the adsorption kinetics of MB at RFGPA prepared calcination temperatures indicated that the adsorption equilibrium of MB was reached after about 72 h. From the results of the adsorption isotherm, we verified that the degree of adsorption increased with increasing MB concentrations. In addition, the adsorption amount (Q) of MB decreased with an increase in calcination temperature. The experimental adsorption isotherm data were well fitted to the Freundlich and Sips equations compared to the Langmuir equation. In order to verify the effects of photocatalytic decomposition (C/C₀) of MB on Fe₂O₃ present in prepared RFGPA, the degree of decomposition of MB was examined under dark and visible conditions. Results indicated that the decomposition of MB in visible conditions was about 3.0 times faster than that in dark conditions.

• Journal of Photoscience
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• v.9 no.2
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• pp.457-459
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• 2002

Sunlight causes various types of adverse skin changes on the sun-exposed areas of the skin, in which the most hazardous one is the induction of malignant skin tumours. FT -IR spectra were obtained from specimens excised from normal skin, BCCs, SCCs, MMs, nevi, lesions of solar keratosis and Bowen's disease. Tissue samples from freshly frozen specimens were cut into 2 sections in strictly sequential order to be stained with H & E for histopathological analysis, and then to be air-dried on CaF$_2$ slide glasses for further spectral data acquisition from defined area of interest. Intra- and inter-sample variations were estimated within grouped lesion categories according to each skin component. Mean spectra for each type of tissue pathology in the 800-1800 $cm^{-1}$ / region was interpreted using the classical group frequency approach that showed the most visible differences in spectra of benign, premalignant and malignant changes directly related to protein conformation and nucleic acid bases. The relative intensity of the nucleic acid peak was increased with progression to malignancy. In addition, PCA was able to evaluate and maximise the differences in the spectra by reducing the number of variables characterizing each patient and pathology category. This type of approach to non-destructively estimate the complexity of IR-spectra of inhomogeneous samples such as skin demonstrates the advantage of FT -IR microspectroscopy to be able to observe diseased states (benign, premalignant, malignant) and distinguish them from normal against a huge background of inter- and intra-subject variability.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.11
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• pp.722-727
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• 2017

Transparent ZnS ceramics were synthesized by hydrothermal synthesis ($180^{\circ}C$ for 70 h), and were sintered by a hot press process at $950^{\circ}C$. To confirm the optical properties of the ZnS ceramics after sintering for various sintering holding times, we performed X-ray diffraction analysis, scanning electron microscopy, and Fourier-transform-infrared spectroscopy. The ZnS nanopowders was found to be single-phase (cubic) without any hexagonal phase. However, the hexagonal phase is formed and increases in content with increasing sintering holding time. The density of the ZnS ceramics was above 99.7%, except for the unsintered one. The ZnS ceramics showed high transmittance (~70%) when sintered for more than 2 h.

• Journal of Microbiology and Biotechnology
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• v.30 no.2
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• pp.226-236
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• 2020

Antibiotic resistance by pathogenic bacteria and fungi is one of the most serious global public health problems in the 21^st century, directly affecting human health and lifestyle. Pseudomonas aeruginosa and Staphylococcus aureus with strong resistance to the common antibiotics have been isolated from Intensive Care Unit patients at Zagazig Hospital. Thus, in this study we assessed the biocidal activity of nanoparticles of silver, copper and zinc synthesized by Fusarium solani KJ 623702 against these multidrug resistant-bacteria. The synthesized Metal Nano-particles (MNPs) were characterized by UV-Vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Zeta potential. The Fourier transform infrared spectroscopy (FTIR) result showed the presence of different functional groups such as carboxyl, amino and thiol, ester and peptide bonds in addition to glycosidic bonds that might stabilize the dispersity of MNPs from aggregation. The antimicrobial potential of MNPs by F. solani against the multidrug-resistant (MDR) P. aeruginosa and S. aureus in addition to the mycotoxigenic Aspergillus awamori, A. fumigatus and F. oxysporum was investigated, based on the visual growth by diameter of inhibition zone. Among the synthesized MNPs, the spherical AgNPs (13.70 nm) displayed significant effect against P. aeruginosa (Zone of Inhibition 22.4 mm and Minimum Inhibitory Concentration 21.33 ㎍/ml), while ZINC oxide Nano-Particles were the most effective against F. oxysporum (ZOI, 18.5 mm and MIC 24.7 ㎍/ml). Transmission Electron Microscope micrographs of AgNP-treated P. aeruginosa showed cracks and pits in the cell wall, with internalization of NPs. Production of pyocyanin pigment was significantly inhibited by AgNPs in a concentration-dependent manner, and at 5-20 ㎍ of AgNPs/ml, the pigment production was reduced by about 15-100%, respectively.

• Polymer(Korea)
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• v.29 no.4
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• pp.369-374
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• 2005

In this work, the calcium alginate microcapsules containing lemon oil were prepared by emulsification-internal gelation and their potential use as aromatherapy was examined by the controlled release system. The lemon oil encapsulated in the alginate was successfully observed by Fourier transform (FT-IR) spectroscopy and differential scanning calorimeter (DSC) measurements. Analysis of the diameters and shapes of microcapsules was conducted by scanning electron microscopy (SEM). The mean diameters ranging from 4 to 7 um and encapsulation yield ranging from 50 to $85\%$ were obtained. The controlled release of the lemon oil at $37^{circ}$ was demonstrated by the infrared moisture determination (IMDB). It was found that the amount of released lemon oil decreased with increasing concentrations of alginate and $CaCl_2$ due to the higher the cross-linking density of the capsules prepared. The oil release from the capsule was measured as a function of physical force. We confirmed that the external factor could control the collapse of capsule wall and the release rate.

• Journal of Pharmacopuncture
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• v.20 no.1
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• pp.36-44
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• 2017

Objectives: The goal of this study was to characterize Suvarna Bhasma Parada Marit by using the Ayurvedic test parameters, physico-chemical tests, and various instrumentation techniques. Methods: Suvarna Bhasma, an Ayurvedic formulation manufactured as per Bharat Bhaishajya Ratnakar 5/8357 (BBR), has been studied using various instrumentation techniques: X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), laser particle size distribution (PSD) analysis, fourier transform infrared spectroscopy (FT-IR), and atomic absorption spectroscopy (AAS), and physico-chemical parameters, such as the loss on drying (LOD), loss on ignition (LOI), and acid insoluble Ash (AIA) were determined. In addition, Ayurvedic tests, such as Rekhapurnatva (enterable in the furrows of the fingers), Varitaratwa (floatable over water), Nirdhoomta (smokeless), Dantagre Kach-Kach (gritty particle feeling between the teeth), were performed. Results: The XRD study showed Suvarna Bhasma to be crystalline in nature and to contain more than 98% gold. The mean size of the gold crystallites was less than 10 microns, and the morphology was globular and irregular. Suvarna Bhasma contains gold as its single and major element, with EDAX and FT-IR spectra showing that it is more than 98% pure gold. The moisture content (LOD) is less than 0.5%, the LOI is less than 2%, and the AIA is not less than 95%. The Ayurvedic tests, as specified above, helped to confirm the quality of Suvarna bhasma prepared as per the text reference (BBR). Conclusion: This chemical characterization of Suvarna Bhasma performed in this study by using modern instrumentation techniques will be helpful in understanding its pharmacological actions and will help in establishing quality protocols and specifications to substantiate the safety, efficacy & quality of Suvarna Bhasma.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.129-129
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• 2010

적외선 검출소자(Infrared Photodetector)는 근적외선에서 원적외선 영역에 이르는 광범위한 파장 범위의 적외선을 이용하는 기기로서 대상물이 방사하는 적외선 영역의 에너지를 흡수하여 이를 영상화할 수 있는 장비이다. 적외선 관련 기술은 2차 세계대전 기간에 태동하였으며, 현재에는 원거리 감지기술 등과 접목되면서 그 활용 분야가 다양해지고 있다. 특히 능동형 정밀 타격무기를 비롯한 감시 정찰 장비 및 지능형 전투 장비 시스템 등에 대한 요구를 바탕으로 보다 정밀하고 신속한 표적 감지 및 정보처리 기술에 관한 연구가 선진국을 통해서 활발히 진행되고 있다. 기존의 Bolometer 형식의 열 감지 소자는 반응 속도가 느리고 측정 감도가 낮은 단점이 있으며, MCT(HgCdTe)를 이용한 적외선 검출기의 경우 높은 기계적 결함과 77K 저온에서 동작해야하기 때문에 발생하는 추가 비용 등이 문제점으로 지적되고 있다[1]. 이에 반해 화합물 반도체 자기조립 양자점(self-assembled quantum dot)을 이용한 적외선 수광소자는 양자점이 가지는 불연속적인 내부 에너지 준위로 인하여, 높은 내부 양자 효율과 온도 안정성을 기대할 수 있으며, 고성능, 고속처리, 저소비전력 및 저소음의 실현이 가능하다. 본 연구에서는 적층 InAs/InGaAs dot-in-a-well 구조를 유기금속화학기상증착법을 이용하여 성장하고 이를 소자에 응용하였다. 균일한 적층 양자점의 성장을 위해서 원자현미경(atomic force microscopy)을 이용하여, 각 층의 양자점의 크기와 밀도를 관찰하였고, photoluminescence (PL)를 이용하여 발광특성을 연구하였다. 각 층간의 GaAs space layer의 두께와 온도 조절 과정을 조절함으로써 균일한 적층 양자점 구조를 얻을 수 있었다. 이를 이용하여 양자점의 전도대 내부의 에너지 준위간 천이(intersubband transition)를 이용하는 n-type GaAs/intrinsic InAs 양자점/n-type GaAs 구조의 양자점 적외선수광소자 구조를 성장하였다. 이 과정에서 상부 n-type GaAs의 성장 온도가 600도 이상이 되는 경우 발광효율이 급격히 감소하고, 암전류가 크게 증가하는 것을 관찰하였다. 이는 InAs 양자점과 주변 GaAs 간의 열에 의한 상호 확산에 의하여 양자점의 전자 구속 효과를 저해하는 것으로 설명된다.

• Polymer(Korea)
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• v.36 no.1
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• pp.9-15
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• 2012

We prepared a series of aromatic liquid crystals (LCs) based on wholly aromatic ester units with the reactive end group methyl maleimide by means of melt condensation method, and the resulting LCs were thermally crosslinked to produce liquid crystalline thermoset (LCT) films. The synthesized LCs and LCTs were characterized with Fourier transform infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechanical analysis (TMA), and polarizing optical microscopy (POM) with a hot stage. The glass transition temperature ($T_g$) and coefficient of thermal expansion are strongly affected by the mesogen units in their main chain structures. The $p$-substituted biphenyl LC was found to have the highest thermal property value.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.112-112
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• 2009

In this study, the effect of a long post-deposition thermal annealing(600 and 1000 $^{\circ}C$) on the surface acoustic wave (SAW) properties of polycrystalline (poly) aluminum-nitride (AlN) thin films grown on a 3C-SiC buffer layer was investigates. The poly-AlN thin films with a (0002) preferred orientation were deposited on the substrates by using a pulsed reactive magnetron sputtering system. Experimental results show that the texture degree of AlN thin film was reduced along the increase in annealing temperature, which caused the decrease in the electromechanical coupling coefficient ($k^2$). The SAW velocity also was decreased slightly by the increase in root mean square (RMS) roughness over annealing temperature. However, the residual stress in films almost was not affect by thermal annealing process due to small lattice mismatch different and similar coefficient temperature expansion (CTE) between AlN and 3C-SiC. After the AlN film annealed at 1000 $^{\circ}C$, the insertion loss of an $IDT/AlN/3C-SiC/SiO_2/Si$ structure (-16.44 dB) was reduced by 8.79 dB in comparison with that of the as-deposited film (-25.23 dB). The improvement in the insertion loss of the film was fined according to the decrease in the grain size. The characteristics of AlN thin films were also evaluated using Fourier transform-infrared spectroscopy (FT-IR) spectra and X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) images.

• Journal of Conservation Science
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• v.35 no.5
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• pp.385-391
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• 2019

In order to examine the material characteristics of a black and white photograph of the Borobudur temple, in Indonesia, several analyses were conducted. A sample was taken from a black and white photograph; microscopy, Fourier transform-infrared spectroscopy, scanning electron microscopy/energy dispersive spectroscopy, X-ray diffraction, and X-ray fluorescence analyses showed that the black and white photograph was composed of four layers including a paper substrate, baryta, binder and surface layers. It was confirmed that the substrate was paper made of cellulose fiber from Cannabis sativa, the baryta layer was made of barium sulfate(BaSO₄) in powder form, the binder was an emulsion containing silver halide, and the surface protective layer was made of gelatin. Since photographs have different characteristics and require different preservation environments depending on the material of construction, it is necessary to study various black and white photographic material characteristics corresponding to each time period.