• Textile Coloration and Finishing
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• v.12 no.4
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• pp.239-247
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• 2000

The coloring matter was extracted from the heartwood of Amur cork tree by distilled water. Change of UV-Visible spectra of coloring matter solution by extraction condition and stability for irradiation were determined, and the effect of repeated dyeing with condition of dyebath and mordanting method on shade depth and lightfastness were also investigated. The results are as follows : 1) Absorbance of Amur cork tree extract increased with the lapse of extraction time. λmax of color solution extracted from Amur cork tree was found at 420, 333, and 262nm. 2) Absorbance of Amur cork tree extract decreased remarkably after 2hr irradiation. 3) The K/S of silk fabrics increased with the increase of dyeing temperature, time, amounts of Amur cork tree for extraction, and pH of color solution. 4) K/S of silk fabrics dyed by repeated dyeing method was affected by pH and concentration of color solution. 5) Lightfastness of silk twice dyed with Amur cork tree extract after pre-mordanted by 8%(o.w.f) chromium acetate was moderately improved.

• Journal of the Korean Chemical Society
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• v.60 no.1
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• pp.28-33
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• 2016

The spiropyran is a typical material having photodegradation properties in the process of photochromism. The spiropyran has been utilized in various applications such as optical switch, optical memories, and biosensor because of its remarkable stability, fast responsive time, stronger color change, and photo-induced controllability. However, the spriropyran is photodegraded by the repetitive optical irradiation. The photodegradation of spiropyran have been investigated by using UV-Visible spectroscopy, nuclear magnetic resonance (NMR), and Raman spectroscopy. Herein, the properties of spiropyran were characterized by using terahertz time-domain spectroscopy (THz-TDS) in the terahertz frequency region. In terahertz region, the measured absorbance of spiropyran was increased due to the photodegradation induced by the repetitive UV irradiation. The absorbance tendency of spiropyran in the terahertz frequency region was compared with that in the visible region, and they were completely opposite to each other.

• Mycobiology
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• v.46 no.1
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• pp.47-51
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• 2018

In the present study, the characterization and properties of silver nanoparticles from Yucca shilerifera leaf extract (AgNPs) were investigated using UV-visible spectroscopic techniques, zeta potential, and dynamic light scattering. The UV-visible spectroscopic analysis showed the absorbance peaked at 460 nm, which indicated the synthesis of silver nanoparticles. The experimental results showed silver nanoparticles had Z-average diameter of 729 nm with lower stability (195.1 mV). Additionally, our dates revealed that AgNPs showed broad spectrum antagonism ($p{\leq}.05$) against Fusarium solani (83.05%) and Macrophomina phaseolina (67.05%) when compared to the control after nine days of incubation. Finally, AgNPs from leaf extracts of Y. shilerifera may be used as an agent of biocontrol of microorganism of importance. However, further studies will be needed to fully understand the agronanotechnological potentialities of AgNPs from Yucca schidigera.

• Bulletin of the Korean Chemical Society
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• v.22 no.5
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• pp.463-466
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• 2001

The determination of Cd2+ and Cu2+ with ammonium pyrrolidinedithiocarbamate (APDC) in Tween 80 micellar media has been studied. The UV-visible spectrum of Cd(PDC)2 complex in Tween 80 media had more sensitivity tha n in chloroform. Although the UV-visible spectrum of the Cu(PDC)2 complex in Tween 80 media had somewhat less sensitivity than that in chloroform, absorbance data of Cu2+ were more reproducible in Tween 80 media. The Cd(PDC)2 and Cu(PDC)2 complexes were very stable at pH 7.0 for up to 100 minutes and could be quantitatively chelated if APDC were added to the sample solution more than 30 times the moles of Cd2+ and Cu2+ . The optimum concentration of Tween 80 was 0.1%. The calibration curves of Cd(PDC)2 and Cu(PDC)2 complexes with good linearity were obtained in 0.1% Tween 80 media. The detection limits of Cd2+ and Cu2+ were 0.0493 ㎍mL-1 and 0.0393 ㎍mL-1 , respectively. Recovery yields of Cd2+ and Cu2+ ions in the spiked real samples were almost 100%. Based on experimental results, this proposed method could be applied to the rapid and simple determination of Cd2+ and Cu2+ in real samples.

• Journal of the Korean Ceramic Society
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• v.54 no.5
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• pp.388-394
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• 2017

Here, utilizing rhodamine B (RhB) as standard color dye, we examined the photo degradation proficiency of $Ag_2Se-Graphene-TiO_2$ nanocomposites under visible light irradiation; samples were prepared by ultrasonication techniques and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopic investigation and UV-Vis absorbance spectra examination. Our outcomes demonstrate that the $Ag_2Se-G-TiO_2$ nanocomposite showed significant photodegradation efficiency as compared with those of $TiO_2-G$ and $Ag_2Se-G$, with around 85.2% of Rhodamine B (RhB) degraded after 180 min. It is concluded that the $Ag_2Se-G-TiO_2$ nanocomposite is a competent candidate for dye pollutants.

• Journal of Environmental Science International
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• v.25 no.12
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• pp.1717-1726
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• 2016

In this study, the reductive decolorization of three acid and basic dyes using modified zero-valent iron (i.e., acid-washed iron (Aw/Fe) and palladium coated iron (Pd/Fe)) at various pH conditions (pH 3~5) was experimentally investigated and the decolorization characteristics were evaluated by analyzing the absorbance spectra and reaction kinetics. In the case of acid dyes such as methyl orange and eriochrome black T, color removal efficiencies increased as initial pH of the dye solution decreased. However, the color removal of methylene blue, a basic dye, was not affected much by the initial pH and more than 70% of color was removed within 10 min. During the decolorization reaction, the absorbance of methyl orange (${\lambda}_{max}=464nm$) and eriochrome black T (${\lambda}_{max}=528nm$) decreased in the visible range but increased in the UV range. The absorbance of methylene blue (${\lambda}_{max}=664nm$) also decreased gradually in the visible range. Pseudo-zero order, pseudo-first order, and pseudo-second order kinetic models were used to analyze the reaction kinetics. The pseudo-second order kinetic model was found to be the best with good correlation. The decolorization reaction rate constants ($k_2$) of methylene blue were relatively higher than those of methyl orange and eriochrome black T. The reaction rate constants of methyl orange and eriochrome black T increased with a decrease in the initial pH.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.351-354
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• 2010

Nickel nanoparticles (Ni NPs) appeared to exhibit the catalytic activity in one-pot cyclocondensation reaction for the preparation of 3,4-dihydropyrimidine-2(1H)-ones via Biginelli reaction from aromatic/heteroaromatic/aliphatic aldehydes, urea/thiourea and ethyl acetoacetate under microwave irradiation has been described. The UV absorbance spectra showed metallic Ni characteristics and appreciate with the particle size determined by Transmission electron microscopy (TEM). After reaction course the Ni NPs can be re-covered and reused without any apparent loss of activity.

• Journal of Environmental Science International
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• v.27 no.7
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• pp.611-620
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• 2018

In this study, a metal-organic framework (MOF) material $NH_2$-MIL-101(Fe) was synthesized using the solvothermal method, and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-visible spectrophotometry, field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and surface area measurements. The XRD pattern of the synthesized $NH_2$-MIL-101(Fe) was similar to the previously reported patterns of MIL-101 type materials, which indicated the successful synthesis of $NH_2$-MIL-101(Fe). The FT-IR spectrum showed the molecular structure and functional groups of the synthesized $NH_2$-MIL-101(Fe). The UV-visible absorbance spectrum indicated that the synthesized material could be activated as a photocatalyst under visible light irradiation. FE-SEM and TEM images showed the formation of hexagonal microspindle structures in the synthesized $NH_2$-MIL-101(Fe). Furthermore, the EDS spectrum indicated that the synthesized material consisted of Fe, N, O, and C elements. The synthesized $NH_2$-MIL-101(Fe) was then employed as an adsorbent and photocatalyst for the removal of Indigo carmine and Rhodamine B from aqueous solutions. The initial 30 min of adsorption for Indigo carmine and Rhodamine B without light irradiation achieved removal efficiencies of 83.6% and 70.7%, respectively. The removal efficiencies thereafter gradually increased with visible light irradiation for 180 min, and the overall removal efficiencies for Indigo carmine and Rhodamine B were 94.2% and 83.5%, respectively. These results indicate that the synthesized MOF material can be effectively applied as an adsorbent and photocatalyst for the removal of dyes.

• Nuclear Engineering and Technology
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• v.50 no.3
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• pp.432-438
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• 2018

The occurrence of saturation in the CR-39 detector reduces and limits its detection dynamic range; nevertheless, this range could be extended using spectroscopic techniques and by measuring the net bulk rate of the saturated CR-39 detector surface. CR-39 detectors were irradiated by 1.5 MeV high alpha-particle fluence varying from $0.06{\times}10^8$ to $7.36{\times}10^8\;alphas/cm^2$ from Am-241 source; thereafter, they were etched in a 6.25N NaOH solution at a temperature of $70^{\circ}C$ for different durations. Net bulk etch rate measurement of the 1.5 MeV alpha-irradiated CR-39 detector surface revealed that rate increases with increasing etching time and reaches its maximum value at the end of the alpha-particle range. It is also correlated with the alpha-particle fluence. The measurements of UV-Visible (UV-Vis) absorbance at 500 and 600 nm reveal that the absorbance is linearly correlated with the fluence of alpha particles at the etching times of 2 and 4 hour. For extended etching times of 6, 10, and 14.5 hour, the absorbance is saturated for fluence values of $4.05{\times}10^8$, $5.30{\times}10^8$, and $7.36{\times}10^8\;alphas/cm^2$. These new methods pave the way to extend the dynamic range of polymer-based solid state nuclear track detectors (SSNTDs) in measurement of high fluence of heavy ions as well as in radiation dosimetry.

• Journal of Technologic Dentistry
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• v.33 no.4
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• pp.291-297
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• 2011

Purpose: The purpose of this study was to know the availability of three photosensitizers, CQ, PD, DA, as a photosensitizer of dental resin composite. We want to know abortion band around visible light region for the using potential possibility as a photosensitizer for visible light cured dental composite resin. And I studied to know the relative photodecomposition ratio of three photosensitizers with or without photoinitiator, DAEM. Methods: The photodecomposition of three photosensitizers were studied by UV absorption spectroscopy in ethanol and determined by same instrument with irradiation time for relative photodecomposition. In order to study the effect of amine on photodecomposition was added the DAEM in the photosensitizer solution and the relative rate was measured by the same procedure with aove mentioned. Results: The all of three photosensitizers are absorbed around visible light region. The relative rate of decrease in absorbance incereased in the order: CQ < BD < PD. The effect of DAEM on the photodecomposition of the photosensitizers was appeared different results without DAEM. The photodecomposition rate of PD and DA decreased somewhat with the addition of amine, while that of CQ increased. The rtealtive photodecomposition rate increased in the oprder: BD ${\leq}$ CQ < PD with the addition of amine, but the differnce was not significant. Conclusion: PD and DA like CQ gives to the possibility of use as a photosensitizer for visible light cured dental composite resin by absorption around visible light region and photodecomposition in the maximum absorption wavelength. And it is showed that PD and DA are not effective decomposed with amine initiator, DAEM but CQ decomposed with DAEM effectively. This result may be due to a different mechanism operating for the decomposition of photosensitizers in the presence of amine.