• Title/Summary/Keyword: IR absorption

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Preparation and Characterization of Reduced Graphene Oxide with Carboxyl Groups-Gold Nanorod Nanocomposite with Improved Photothermal Effect (향상된 광열 효과를 갖는 카르복실화된 환원 그래핀옥사이드-골드나노막대 나노복합체의 제조 및 특성 분석)

  • Lee, Seunghwa;Kim, So Yeon
    • Applied Chemistry for Engineering
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    • v.32 no.3
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    • pp.312-319
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    • 2021
  • Photothermal therapy is a treatment that necrotizes selectively the abnormal cells, in particular cancer cells, which are more vulnerable to heat than normal cells, using the heat generated when irradiating light. In this study, we synthesized a reduced graphene oxide with carboxyl groups (CRGO)-gold nanorod (AuNR) nanocomposite for photothermal treatment. Graphene oxide (GO) was selectively reduced and exfoliated at high temperature to synthesize CRGO, and the length of AuNR was adjusted according to the amount of AgNO3, to synthesize AuNR with a strong absorption peak at 880 nm, as an ideal photothermal agent. It was determined through FT-IR, thermogravimetric and fluorescence analyses that more carboxyl groups were conjugated with CRGO over RGO. In addition, CRGO exhibited excellent stability in aqueous solutions compared to RGO due to the presence of carboxylic acid. The CRGO-AuNR nanocomposites fabricated by electrostatic interaction have an average size of ~317 nm with a narrow size distribution. It was confirmed that under radiation with a near-infrared 880 nm laser which has an excellent tissue transmittance, the photothermal effect of CRGO-AuNR nanocomposites was greater than that of AuNR due to the synergistic effect of the two photothermal agents, CRGO and AuNR. Furthermore, the results of cancer cell toxicity by photothermal effect revealed that CRGO-AuNR nanocomposites showed superb cytotoxic properties. Therefore, the CRGO-AuNR nanocomposites are expected to be applied to the field of anticancer photothermal therapy based on their stable dispersibility and improved photothermal effect.

Degradation of Antibiotics Using Silver Decorated Heterojunction Carbon Nitride under Visible Light (은 장식 이종접합 질화탄소를 이용한 가시광선 조건에서의 항생제 분해 연구)

  • Taeyoon, Lee
    • Journal of the Korean GEO-environmental Society
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    • v.24 no.3
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    • pp.23-27
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    • 2023
  • Graphitic carbon nitride (g-C3N4) has been used as effective photocatalyst for degradation of antibiotics under visible light irradiation. However, the fast recombination of hole-electron pair may limit their photocatalytic efficiency. In our study, Ag was grafted on g-C3N4/g-C3N4 isotype heterojunction by a microwave-assisted decomposition method. The structure and physical properties of heterojunction photocatalyst were characterized through X-ray diffraction, UV-DRS, FT-IR, and Photoluminescence analyses. Ag decorated g-C3N4/g-C3N4 isotype heterojunction exhibited excellent photocatalytic activity for degradation of sulfamethoxazole under irradiation under visible light irradiation within 210 min, which is higher than g-C3N4/g-C3N4 isotype heterojunction and bulk g-C3N4. The addition of Ag may broaden the visible light absorption and restrict the recombination of hole-electron pair because of the surface plasmons resonance, resulting in the improving the photocatalytic activity.

Characterization of TMA-A zeolite incorporated by ZnO nanocrystals (ZnO 나노결정을 담지한 TMA-A 제올라이트의 특성분석)

  • Lee, Seok Ju;Lim, Chang Sung;Kim, Ik Jin
    • Analytical Science and Technology
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    • v.21 no.1
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    • pp.58-63
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    • 2008
  • Nano-sized ZnO crystals were successfully incorporated using ion exchange method in TMA-A zeolite synthesized by the hydrothermal method. The optimal composition for the synthesis of TMA-A zeolite was resulted in a solution of $Al(i-pro)_3$ : 2.2 TEOS : 2.4 TMAOH : 0.3 NaOH : 200 $H_2O$. 0.3 g of TMA-A zeolite and 5 mol of $ZnCl_2$ solution were employed for the preparation of ZnO incorporated TMA-A zeolite. The crystallization process of ZnO incorporated TMA-A zeolite was analyzed by X-ray diffraction (XRD). The incorporated nano-sized ZnO crystals and the crystallinity of TMA-A zeolite were evaluated by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The size of the incorporated nano-sized ZnO crystals was 3~5 nm, while the TMA-A zeolite was 60~100 nm. The bonding structure and absorption of the ZnO incorporated TMA-A zeolite were compared with the ZnO and TMA-A zeolite by the FT-IR analysis. Subsequentlly, the ZnO incorporated TMA-A zeolite showed the photoluminescent characteristics on the wavelengths of 330~260 nm and 260~230 nm by measurement of UV spectrophotometer.

Fabrication and Characterization of Si Quantum Dots in a Superlattice by Si/C Co-Sputtering (실리콘과 탄소 동시 스퍼터링에 의한 실리콘 양자점 초격자 박막 제조 및 특성 분석)

  • Kim, Hyun-Jong;Moon, Ji-Hyun;Cho, Jun-Sik;Park, Sang-Hyun;Yoon, Kyung-Hoon;Song, Jin-Soo;O, Byung-Sung;Lee, Jeong-Chul
    • Korean Journal of Materials Research
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    • v.20 no.6
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    • pp.289-293
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    • 2010
  • Silicon quantum dots (Si QDs) in a superlattice for high efficiency tandem solar cells were fabricated by magnetron rf sputtering and their characteristics were investigated. SiC/$Si_{1-x}C_x$ superlattices were deposited by co-sputtering of Si and C targets and annealed at $1000^{\circ}C$ for 20 minutes in a nitrogen atmosphere. The Si QDs in Si-rich layers were verified by transmission electron microscopy (TEM) and X-ray diffraction. The size of the QDs was observed to be 3-6 nm through high resolution TEM. Some crystal Si and -SiC peaks were clearly observed in the grazing incident X-ray diffractogram. Raman spectroscopy in the annealed sample showed a sharp peak at $516\;cm^{-1}$ which is an indication of Si QDs. Based on the Raman shift the size of the QD was estimated to be 4-6 nm. The volume fraction of Si crystals was calculated to be about 33%. The change of the FT-IR absorption spectrum from a Gaussian shape to a Lorentzian shape also confirmed the phase transition from an amorphous phase before annealing to a crystalline phase after annealing. The optical absorption coefficient also decreased, but the optical band gap increased from 1.5 eV to 2.1 eV after annealing. Therefore, it is expected that the optical energy gap of the QDs can be controlled with growth and annealing conditions.

Spectroscopic Characteristics of Ruby from Gorno-Badakhshan, Tajikistan (타지키스탄 고르노바다흐샨주 지역 루비에 대한 분광학적 특성 연구)

  • Chung, Sol Lim;Park, Jong Wan
    • The Journal of the Petrological Society of Korea
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    • v.22 no.1
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    • pp.1-8
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    • 2013
  • Physical properties, XRF, UV-Vis, FTIR studies were carried out in order to characterize gemological features of ruby from Tajikistan. Fluorescence reaction of the Tajikistan ruby to short wave ultraviolet was moderate to very strong in red and long wave ultraviolet rays was weakly detected. UV-visible analysis strong absorption bands at 468.5, 475, 476.5 nm and broaden bands at 550 nm were observed for ruby due to $Cr^{3+}$. According to FT-IR analysis, all rubies from Tajikistan showed the similar patterns and kaolinite peaks at 3500, 3617, 3630, $3677cm^{-1}$ and boehmite broaden absorption bands at 3085 and $3320cm^{-1}$. Inclusions in Tajikistan ruby are observed solid inclusions, negative crystals, needle and silk inclusions. These distinctive characteristics mentioned above can be used to identify the locality and source of ruby stones from Tajikistan.

Real-Time Monitoring of Mitochondrial ATP Synthesis and Hydrolysis by Surface Infrared Spectroscopy

  • Yamaguchi, Ryo-Taro;Hirano-Iwata, Ayumi;Aonuma, Yuki;Yoshimura, Yuya;Shinohara, Yasuo;Kimura, Yasuo;Niwano, Michio
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.108-109
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    • 2013
  • Mitochondria play key roles in the production of cell's energy. Their dominant function is the synthesis of adenosine 5'-triphosphate (ATP) from adenosine diphosphate (ADP) and phosphate (Pi) through the oxidative phosphorylation. Evaluation of drug-induced mitochondrial toxicity has become increasingly important since mitochondrial dysfunction has recently been implicated in numerous diseases including cancer and diabetes mellitus. Mitochondrial functions have been monitored via oxygen consumption, mitochondrial membrane potential, and more importantly via ATP synthesis since ATP synthesis is the most essential function of mitochondria. Various analytical methods have been employed to investigate ATP synthesis in mitochondria, including high performance liquid chromatography (HPLC), bioluminescence technique, and pH measurement. However, most of these methods are based on destructive analysis or indirect monitoring through the enzymatic reaction. Infrared absorption spectroscopy (IRAS) is one of the useful techniques for real-time, label-free, and direct monitoring of biological reactions [1,2]. However, the strong water absorption requires very short path length in the order of several micrometers. Transmission measurements with thin path length are not suitable for mitochondrial assays because solution handlings necessary for evaluating mitochondrial toxicity, such as rapid mixing of drugs and oxygen supply, are difficult in such a narrow space. On the other hand, IRAS in the multiple internal reflection (MIR) geometry provides an ideal optical configuration to combine solution handling and aqueous-phase measurement. We have recently reportedon a real-time monitoring of drug-induced necrotic and apoptotic cell death using MIR-IRAS [3,4]. Clear discrimination between viable and damaged cells has been demonstrated, showing a promise as a label-free and real-time detection for cell-based assays. In the present study, we have applied our MIR-IRAS system to mitochondria-based assays by monitoring ATP synthesis in isolated mitochondria from rat livers. Mitochondrial ATP synthesis and hydrolysis were in situ monitored with MIR-IRAS, while dissolved oxygen level and solution pH were simultaneously monitored with O2 and pH electrodes, respectively. It is demonstrated that ATP synthesis and hydrolysis can be monitored by the IR spectral changes in phosphate groups in adenine nucleotides and MIR-IRAS is useful for evaluating time-dependent drug effects of mitochondrial toxicants.

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Studies on the carotenoids in the viscera of abalone (Haliotis discus hannai) (전복(Haliotis discus hannai) 내장(內臟)의 Carotenoid에 관(關)한 연구(硏究))

  • Ahn, Seung-Yo
    • Applied Biological Chemistry
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    • v.17 no.4
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    • pp.257-274
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    • 1974
  • The studies on the carotenoids in the viscera of abalone (Haliotis discus hannai) have been-carried out. The pigments were extracted with acetone-methanol mixture (4 : 1) from the viscera of abalones which were caught around the coastal water of Korea from March to August. The individual carotenoid in the extracts was separated and purified by the silica gel TLC, $Mg(OH)_2$ impregnated paper chromatography and $Mg_2(OH)_2CO_3$ TLC. The isolated eleven carotenoids were investigated and identified by epoxide test, partition test, reduction with sodium borohydride, alkaline hydrolysis, co-chromatography and comparative test with reference carotenoids and electronic and IR absorption spectrophotometry. ${\alpha}$-Carotene, ${\beta}$-carotene. lutein, zeaxanthin, siponaxanthin, siponein, fucoxanthin, loroxan-thin-like and fucoxanthinol-like have been identified among the eleven carotenoids isolated. It has been found that fucoxanthin, on alkaline treatment, was transformed to the product of which chromophore was the same one as fucochrome and semifucoxanthol. Among the identified nein carotenoids siphonaxanthin, siponein, fucoxanthin, loroxanthin-like and fucoxanthinol-like have not been reported previously to be contained in the shellfish.

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Oxidation behavior on the surface of titanium metal specimens at high temperatures (300~1000℃) (고온 (300~1000 ℃)에서 티타늄 금속시편의 표면 산화거동)

  • Park, Yang-Soon;Han, Sun-Ho;Song, Kyuseok
    • Analytical Science and Technology
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    • v.22 no.6
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    • pp.464-470
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    • 2009
  • For the investigation of the oxidation behavior for titanium metal at various temperatures, titanium specimens were heated for 2 hours in the range of $300{\sim}1000^{\circ}C$, individually. And then X-ray diffraction(XRD), scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic analyses were carried out. At $300^{\circ}C$, infrared absorption bands on the surface of the titanium specimen were shown in a spectrum by the oxygen uptake of titanium metal(hexagonal). At increased temperature, not only infrared absorption bands but also X-ray diffraction peaks for the titanium oxide were grown and shifted to low wave number ($cm^{-1}$) and angle($^{\circ}$) due to the more oxygen diffusion into titanium metal. At $700^{\circ}C$, $Ti_3O$ (hexagonal phase) was identified by X-ray diffractometer. $TiO_2$ (rutile, tetragonal phase) layer was produced on the surface of the specimen below $1{\mu}m$ in thickness at $600^{\circ}C$, and grown about $2{\mu}m$ at $700^{\circ}C$ and with $110{\mu}m$ in thickness at $1000^{\circ}C$. Above $900^{\circ}C$, (110) plane of the crystal on the surface of rutile-$TiO_2$ layer was grown.

Near-IR Spectroscopic Studies of the Hydrogen Bonding Between Thiopropionamide and N,N-Dimethylalkylamide in Carbon Tetrachloride (사염화탄소 중에서 Thiopropionamide와 N,N-Dimethylalkylamide사이의 수소결합에 관한 분광학적 연구)

  • Byung-Chul Kim;Chang-Ju Yoon;Kyuseok Song;Young Sang Choi
    • Journal of the Korean Chemical Society
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    • v.33 no.2
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    • pp.156-163
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    • 1989
  • The $ν_a+amide II$ combination band of thiopropionamide has been recorded for investigation of Hydrogen bonding between thiopropionamide (TPA) and N,N-dimethylalkylamide (DMF, DMA and DMP) in carbon tetrachloride over the range of $5^{\circ}$ to $55^{\circ}$. The combination band of monomeric TPA and hydrogen-bonded TPA can be resolved by Lorentzian-Gaussian product function into monomeric TPA and hydrogen-bonded TPA with amides. The association constants ($K_1$) for the hydrogen-bonded TPA were calculated by the concentrations of the monomeric TPA and the hydrogen-bonded TPA obtained from the computer resolved absorption bands. Thermodynamic parameters for the Hydrogen bonding have been evaluated by the analysis of the temperature dependent spectra. The ${\Delta}$$H^{\circ}$ of hydrogen-bonded TPA with DMF, DMA and DMP have been found to be-12.5, -13.5 and -14.1 kJ/mol, respectively. The corresponding ${\Delta}$$S^{\circ}$for the above system were -15.2, -17.9 and -22.3 J/mol${\cdot}$deg, respectively.

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Characterization of the ZnSe/ZnS Core Shell Quantum Dots Synthesized at Various Temperature Conditions and the Water Soluble ZnSe/ZnS Quantum Dot

  • Hwang, Cheong-Soo;Cho, Ill-Hee
    • Bulletin of the Korean Chemical Society
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    • v.26 no.11
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    • pp.1776-1782
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    • 2005
  • ZnSe/ZnS, UV-blue luminescent core shell quantum dots, were synthesized via a thermal decomposition reaction of organometallic zinc and solvent coordinated Selenium (TOPSe) in a hot solvent mixture. The synthetic conditions of the core (ZnSe) and the shell (ZnS) were independently studied at various reaction temperature conditions. The obtained colloidal nanocrystals at corresponding temperatures were characterized for their optical properties by UV-vis, room temperature solution photoluminescence (PL) spectroscopy, and further obtained powders were characterized by XRD, TEM, and EDXS analyses. The synthetic temperature condition to obtain the best PL emission intensity for the ZnSe core was 300 ${^{\circ}C}$, and for the optimum shell capping, the temperature was 135 ${^{\circ}C}$. At this temperature, solution PL spectrum showed a narrow emission peak at 427 nm with a PL efficiency of 15%. In addition, the measured particle sizes for the ZnSe/ZnS nanocomposite via TEM were in the range of 5 to 12 nm. Furthermore, we have synthesized water-soluble ZnSe/ZnS nanoparticles by capping the ZnSe/ZnS hydrophobic surface with mercaptoacetate (MAA) molecules. For the obtained aqueous colloidal solution, the UV-vis spectrum showed an absorption peak at 250 nm, and the solution PL emission spectrum showed a peak at 425 nm, which is similar to that for hydrophobic quantum dot ZnSe/ZnS. However, the calculated PL efficiency was relatively low (0.1%) due to the luminescence quenching by water and MAA molecules. The capping ligand was also characterized by FT-IR spectroscopy, with the carbonyl stretching peak in the mercaptoacetate molecule appearing at 1575 $cm ^{-1}$. Finally, the particle sizes of the MAA capped ZnSe/ZnS were measured by TEM, showing a range of 12 to 17 nm.