• Journal of Photoscience
• /
• v.9 no.2
• /
• pp.106-109
• /
• 2002

Archaeal rhodopsins possess retinal molecule as their chromophores, and their light-energy and light-signal conversions are triggered by all-trans to 13-cis isomerization of the retinal chromophore. Relaxation through structural changes of protein then leads to functional processes, proton pump in bacteriorhodopsin (bR) and transducer activation in phoborhodopsin (pR). It is known that sensory rhodopsins can pump protons in the absence of their transducers. Thus, there should be common and specific features in their protein structural changes for function. In this paper, our r ecent studies on pR from Natronobacterium pharaonis (ppR) by means of low-temperature Fourier-transform infrared (FTIR) spectroscopy are compared with those of bR. In particular, protein structural changes upon retinal photoisomerization are studied. Comparative investigation of ppR and bR revealed the similar structures of the polyene chain of the chromophore and water-containing hydrogen-bonding network, whereas the structural changes upon photoisomerization were more extended in ppR than in bR. Extended protein structural changes were clearly shown by the assignment of the C=O stretch of Asnl05. FTIR studies of a ppR mutant with the same retinal binding site as in bR revealed that the Schiff base region is important to determine their colors.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.141-141
• /
• 2010

The effect of thermal anneal on the characteristics of structural properties and the enhancement of luminescence and photovoltaic (PV) characteristics of silicon-rich silicon-nitride films were investigated. By using an ultra high vacuum ion beam sputtering deposition, B-doped silicon-rich silicon-nitride (SRSN) thin films, with excess silicon content of 15 at. %, on P-doped (n-type) Si substrate was fabricated, sputtering a highly B doped Si wafer with a BN chip by N plasma. In order to examine the influence of thermal anneal, films were then annealed at different temperature up to $1100^{\circ}C$ under $N_2$ environment. Raman, X-ray diffraction, and X-ray photoemission spectroscopy did not show any reliable evidence of amorphous or crystalline Si clusters allowing us concluding that nearly no Si nano-cluster could be formed through the precipitation of excess Si from SRSN matrix during thermal anneal. Instead, results of Fourier transform infrared and X-ray photoemission spectroscopy clearly indicated that defective, amorphous Si-N matrix of films was changed to be well-ordered thanks to high temperature anneal. The measurement of spectral ellipsometry in UV-visible range was carried out and we found that the optical absorption edge of film was shifted to higher energy as the anneal temperature increased as the results of thermal anneal induced formation of $Si_3N_4$-like matrix. These are consistent with the observation that higher visible photoluminescence, which is likely due to the presence of Si-N bonds, from anneals at higher temperature. Based on these films, PV cells were fabricated by the formation of front/back metal electrodes. For all cells, typical I-V characteristic of p-n diode junction was observed. We also tried to measure PV properties using a solar-simulator and confirmed successful operation of PV devices. Carrier transport mechanism depending on anneal temperature and the implication of PV cells based on SRSN films were also discussed.

• Journal of Biomedical Engineering Research
• /
• v.27 no.5
• /
• pp.218-223
• /
• 2006

We examined the effects of ${\beta}$-glucan-reinforced PLGA film and scaffold on HDFs (human dermal fibroblast) attachment and proliferation. The PLGA films were prepared by simple solvent-casting method. The prepared films were grafted with $(1{\to}3)(1{\to}6)-{\beta}-glucan$ in various ratios after plasma treatment on surface. The surface of the film was characterized by contact angle measurement, scanning electron microscope (SEM), and Fourier-transform infrared spectrophotometer (FT-IR). The amount of $(1{\to}3)(1{\to}6)-{\beta}-glucan$ in the prepared film was indirectly determined by phenol-sulfuric acid method. The HDFs (Human dermal fibroblasts) were used to evaluate the cell attachment and proliferation on PLGA specimens before and after plasma/${\beta}-glucan$ treatment. The result showed that the plasma treated groups exhibited more mont of ${\beta}-glucan$ might be grafted than the non plasma treated groups. Cell attachment was significantly enhanced in the plasma/${\beta}-glucan$ grafted group after 4 hours incubation (p<0.05) due to the improved hydrophilicity and cytoactivity effect of the ${\beta}-glucan$. The cell proliferation of plasma/${\beta}-glucan$ (2mg/ml) grafted group was the highest rate among the groups (p<0.05).

• Journal of the Mineralogical Society of Korea
• /
• v.11 no.1
• /
• pp.20-31
• /
• 1998

Adsorption of metal elements onto illite and halloysite was investigated at $25^{\circ}C$ using pollutant water collected from the gold-bearing metal mine. Incipient solution of pH 3.19 was reacted with clay minerals as a function of time: 10 minute, 30 minute, 1 hour, 12 hour, 24 hour, 1 day, 2 day, 1 week, and 2 week. Twenty-seven cations and six anions from solutions were analyzed by AAs (atomic absorption spectrometer), ICP(induced-coupled plasma), and IC (ion chromatography). Speciation and saturation index of solutions were calculated by WATEQ4F and MINTEQA2 codes, indicating that most of metal ions exist as free ions and that there is little difference in chemical species and relative abundances between initial solution and reacted solutions. The adsorption results showed that the adsorption extent of elements varies depending on mineral types and reaction time. As for illite, adsorption after 1 hour-reaction occurs in the order of As>Pb>Ge>Li>Co, Pb, Cr, Ba>Cs for trace elements and Fe>K>Na>Mn>Al>Ca>Si for major elements, respectively. As for halloysite, adsorption after 1 hour-reaction occurs in the order of Cu>Pb>Li>Ge>Cr>Zn>As>Ba>Ti>Cd>Co for trace elements and Fe>K>Mn>Ca>Al>Na>Si for major elements, respectively. After 2 week-reaction, the adsorption occurs in the order of Cu>As>Zn>Li>Ge>Co>Ti>Ba>Ni>Pb>Cr>Cd>Se for trace elements and Fe>K>Mn>Al, Mg>Ca>Na, Si for major elements, respectively. No significant adsorption as well as selectivity was found for anions. Although halloysite has a 1:1 layer structure, its capacity of adsorption is greater than that of illite with 2:1 structure, probably due to its peculiar mineralogical characteristics. According to FTIR (Fourier transform infrared spectroscopy) results, there was no shift in the OH-stretching bond for illite, but the ν1 bond at 3695 cm-1 for halloysite was found to be stronger. In the viewpoint of adsorption, illite is characterized by an inner-sphere complex, whereas halloysite by an outer-sphere complex, respectively. Initial ion activity and dissociation constant of metal elements are regarded as the main factors that control the adsorption behaviors in a natural system containing multicomponents at the acidic condition.

• Journal of Soil and Groundwater Environment
• /
• v.20 no.2
• /
• pp.22-31
• /
• 2015

In the present study, surface of laccase producing Ceriporia lacerata was modified using 4-bromobutyryl chloride and polyethylenimine. The modified biomass was freeze dried and utilized as a biosorbent for the removal of Ni(II) from aqueous solution. The physicochemical properties of the biosorbent were analyzed using scanning electron microscopy and Fourier transform infrared spectroscopy. Batch experiments were carried out as a function of contact time (0-60 min), pH (2 to 8), adsorbent dosage (25-150 mg), and initial Ni(II) concentration (25-125 mg/L). The results indicate that surface modified biosorbent effectively adsorbed (9.5 mg/0.1 g biomass) Ni(II) present in the solution. The equilibrium adsorption data were modeled with different kinetic and isotherm models. The Ni(II) adsorption followed pseudo-first-order kinetics (R² = 0.998) and Langmuir isotherm (R² = 0.994) model. Hydroxyl and carbonyl functional groups present in biomass play a major role in the adsorption of Ni(II). The adsorbed Ni(II) from the biosorbent was successfully desorbed (85%) by 1M HCl. The results of the study indicate that the surface modified C. lacerate biomass could be used for the treatment of Ni(II) contaminated ground waters.

• Nuclear Engineering and Technology
• /
• v.54 no.3
• /
• pp.1062-1070
• /
• 2022

In the present communication, pure and stable α-Bismuth Oxide (Bi₂O₃) nanoparticles (NPs) were synthesized by low temperature solution combustion method using urea as a fuel and calcined at 500℃. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Visible absorption spectroscopy. The PXRD pattern confirms the formation of mono-clinic, stable and low temperature phase α-Bi₂O₃. The direct optical energy band gap was estimated by using Wood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range 0.081-1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shielding parameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accurate theory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present work opens new window to use this facile, economical, efficient, low temperature method to synthesize nanomaterials for X-ray/gamma ray shielding purpose.

• Tribology and Lubricants
• /
• v.32 no.5
• /
• pp.141-146
• /
• 2016

The diketopyrrolopyrrole (DPP) pigment is a bicyclic 8-π-electron system containing two lactam units. Typical DPP derivative pigments have melting points of over 350°C and very low solubility in most solvents, and show absorption in the visible region with a molar extinction coefficient of 33,000 dm²mol⁻¹ and strong photoluminescence with maxima in the range 500–600 nm. X-ray structure analyses of DPP show that the whole molecule is almost in one plane. The phenyl rings are twisted out of the heterocyclic plane and the intermolecular hydrogen bonding between neighboring lactam NH and carbonyl units influences the structure of the DPP pigment in the solid state. In this study, mono-N-alkylation and mono-N-arylation were undertaken for Pigment Red 264 or Pigment Orange 73 with alkyl halide and aryl halide, respectively, in the presence of sodium tert-butoxide as a base catalyst to improve the solubility of DPP pigments and their application as CO₂ indicators. The synthetic yield was in the range 11–88%. The indicator dyes are highly soluble in organic solvents and shows pH-dependent absorption (λ_max 501 and 572 nm for the protonated and deprotonated forms, respectively) and emission (λ_max 524 and 605 nm for the protonated and deprotonated forms, respectively) spectra. The mono-N-alkylated and mono-N-arylated DPP pigment was identified by ¹H-NMR (¹H-Nuclear Magnetic Resonance Spectrometer), FT-IR (Fourier Transform Infrared Spectroscopy), and MS (Mass Spectrometry). According to the results of color and hue properties obtained by a color matching analyzer, the synthesized DPP pigment material can be used as a CO₂ indicator.

• Animal Bioscience
• /
• v.36 no.3
• /
• pp.451-460
• /
• 2023

Objective: This program aimed to reveal the association of feed intrinsic molecular structure with nutrient supply to animals from canola feedstocks and co-products from bio-oil processing. The special objective of this study was to quantify the relationship between molecular spectral feature and nutrient availability and develop nutrient prediction equation with vibrational molecular structure spectral profiles. Methods: The samples of feedstock (canola oil seeds) and co-products (meals and pellets) from different bio-oil processing plants in Canada (CA) and China (CH) were submitted to this molecular spectroscopic technique and their protein and carbohydrate related molecular spectral features were associated with the nutritional results obtained through the conventional methods of analyses for chemical and nutrient profiles, rumen degradable and intestinal digestible parameters. Results: The results showed that the spectral structural carbohydrates spectral peak area (ca. 1,487.8 to 1,190.8 cm^-1) was the carbohydrate structure that was most significant when related to various carbohydrate parameters of canola meals (p<0.05, r>0.50). And spectral total carbohydrate area (ca. 1,198.5 to 934.3 cm^-1) was most significant when studying the various carbohydrate parameters of canola seeds (p<0.05, r>0.50). The spectral amide structures (ca. 1,721.2 to 1,480.1 cm^-1) were related to a few chemical and nutrient profiles, Cornell Net Carbohydrate and Protein System (CNCPS) fractions, truly absorbable nutrient supply based on the Dutch protein system (DVE/OEB), and NRC systems, and intestinal in vitro protein-related parameters in co-products (canola meals). Besides the spectral amide structures, α-helix height (ca. 1,650.8 to 1,643.1 cm^-1) and β-sheet height (ca. 1,633.4 to 1,625.7 cm^-1), and the ratio between them have shown to be related to many protein-related parameters in feedstock (canola oil seeds). Multi-regression analysis resulted in moderate to high R² values for some protein related equations for feedstock (canola seeds). Protein related equations for canola meals and carbohydrate related equations for canola meals and seeds resulted in weak R² and low p values (p<0.05). Conclusion: In conclusion, the attenuated total reflectance Fourier transform infrared spectroscopy vibrational molecular spectroscopy can be a useful resource to predict carbohydrate and protein-relates nutritional aspects of canola seeds and meals.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.46 no.5
• /
• pp.608-615
• /
• 2017

The objective of this study was to evaluate the physicochemical, structural, and rheological properties of new domestic potato cultivars ('Goun', 'Sebong', and 'Jinsun') against the foreign potato cultivar 'Atlantic'. Based on the results obtained from scanning electron micrograph, X-ray, and Fourier transform infrared spectrum analyses, the structural properties of all potato flours were not considerably different. Rapid visco analyzer analyses showed that the setback viscosities of 'Goun', 'Sebong', and 'Jinsun' were significantly lower than that of 'Atlantic'. For steady shear rheological properties, potato flour dispersions showed shear-thinning behaviors (n=0.45~0.49) at $25^{\circ}C$. Apparent viscosity and consistency index of 'Atlantic' were similar to those of 'Sebong' and 'Jinsun'. For dynamic shear rheological properties, storage modulus (G′) and loss modulus increased, whereas complex viscosity (${\eta}^*$) was reduced with increasing frequency from 0.63 to 62.8 rad/s. G′ and ${\eta}^*$ values of 'Jinsun' were significantly higher than those of the other potato cultivars.

• Restorative Dentistry and Endodontics
• /
• v.26 no.1
• /
• pp.86-94
• /
• 2001

기존의 광중합기는 높은 광강도를 제공함으로써 광중합 복합레진을 최대한 단축된 시간내의 중합을 목표로 하였다. 이러한 높은 광강도는 복합레진의 중합깊이, 중합률면에서는 우수하나 중합 반응속도가 빠름으로 인해 중합시 응력 발생이 높아진다는 일련의 보고가 있다. 최근에는 광중합 속도를 늦춤으로써 변연적합도 및 중합시 응력 발생을 낮추는 새로운 중합방법들이 제시되고 있다. 이에 본 실험에서는 광조사 강도의 변화가 광중합 복합레진의 중합반응 과정에 미치는 영향 및 중합된 복합레진의 중합률에 대한 영향을 분석하고자 하였다. 5개의 혼합형 광중합 복합레진 (Z-100, Spectrum, Z-250, Clearfil AP-X, P-60)을 사용하였으며 중합시 적용된 광조사 강도에 따라 6개의 실험군으로 정의하였다. 실험군과 이에 따른 광조사 방법은 다음과 같다. 1군은 110mW/$\textrm{cm}^2$로 40초 중합, 2군 210mW/$\textrm{cm}^2$로 40초 중합, 3군 410mW/$\textrm{cm}^2$로 40초 중합, 4군 620mW/$\textrm{cm}^2$로 40초 중합, 5군 110mW/$\textrm{cm}^2$로 10초 중합 후 1분 뒤 620mW/$\textrm{cm}^2$로 30초 중합, 6군 210mW/$\textrm{cm}^2$로 10초 중합 후 1분 뒤 410mW/$\textrm{cm}^2$로 30초 중합하였다. 광중합시 중합 반응 양상에 관한 분석은 시차주사 열계량기를 이용하여 37$^{\circ}C$ 항온상태에서 10분간의 열흐름곡선을 기록하였다. 기록된 열흐름곡선에서 중합 반응시 나타나는 중합열 및 최대 중합열에 이르는 시간을 기록하여 중합반응 속도를 측정하였다. 중합된 복합레진의 중합률은 Fourier Transform Infrared Spectrometer(FTIR)를 이용하였으며 2mm 두께의 복합레진 하방에서의 중합률을 측정하였다. 측정된 결과는 ANOVA 및 Student-Newman-Keuls 방법을 이용하여 유의성을 검증하였다. 실험결과 다음과 같은 결론을 얻었다. 1. 광중합 복합레진 중합시 광조사 강도가 증가할수록 중합열은 증가하였으나 통계적 유의성은 보이지 않았다 (p>0.05). 2. 최대 중합열에 이르는 시간은 광조사 강도가 증가할수록 단축되었다. 이단계 중합방법을 사용한 경우 중합반응 속도를 감소시킬 수 있음을 보였다. 3. 광조사 강도가 증가할수록 중합률은 증가하였다. 이단계 중합방법을 사용한 경우 연속적인 고광강도를 사용한 경우와 유사한 높은 중합률을 보였다. 4. 중합률면에서 광중합복합레진의 중합시 400mW/$\textrm{cm}^2$ 이상의 광강도가 필요한 것으로 나타났다.