• Bulletin of the Korean Chemical Society
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• v.22 no.2
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• pp.219-227
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• 2001

The silver colloidal effects on the excited-state structure and intramolecular charge transfer (ICT) of p-N,N-dimethylaminobenzoic acid (DMABA) in aqueous cyclodextrin (CD) solutions have been investigated by UV-VIS absorption, steady-state and time-resolved fluorescence, and transient Raman spectroscopy. As the concentration of silver colloids increases, the ratio of the ICT emission to the normal emission (Ia /Ib) of DMABA in the aqueous $\alpha-CD$ solutions are greatly decreased while the Ia /Ib values in the aqueous B-CD solutions are significantly enhanced. It is also noteworthy that the ICT emission maxima are red-shifted by 15-40 nm upon addition of silver colloids, implying that DMABA encapsulated in $\alpha-CD$ or B-CD cavity is exposed to more polar environment. The transient resonance Raman spectra of DMABA in silver colloidal solutions demonstrate that DMABA in the excited-state is desorbed from silver colloidal surfaces as demonstrated by the disappearance of νs (CO2-)(1380 cm-1 ) with appearance of ν(C-OH)(1280 cm -1) band, respectively. Thus, in the aqueous B-CD solutions the carboxylic acid group of DMABA in the excited-state can be readily hydrogen-bonded with the secondary hydroxyl group of B-CD while in aqueous and $\alpha-CD$ solutions the carboxylic acid group of DMABA has the hydrogen-bonding interaction with water. Consequently, in the aqueous B-CD solutions the enhancement of the Ia /Ia value arises from the intermolecular hydrogen-bonding interaction between DMABA and the secondary hydroxyl group of B-CD as well as the lower polarity of the rim of the B-CD cavity compared to bulk water. This is also supported by the increase of the association constant for DMABA/ B-CD complex in the presence of silver colloids.

• Journal of Audiology & Otology
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• v.23 no.2
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• pp.69-75
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• 2019

Background and Objectives: The antioxidant ebselen will be able to limit or prevent the ototoxicity arising from 2-hydroxypropyl-β-cyclodextrin (HPβCD). Niemann-Pick Type C (NPC) disease is a disorder of lysosomal storage manifested in sphingolipidosis. Recently, it was noted that experimental use of HPβCD could partially resolve the symptoms in both animals and human patients. Despite its desirable effect, HPβCD can induce hearing loss, which is the only major side effect noted to date. Understanding of the pathophysiology of hearing impairment after administration of HPβCD and further development of preventive methods are essential to reduce the ototoxic side effect. The mechanisms of HPβCD-induced ototoxicity remain unknown, but the resulting pathology bears some resemblance to other ototoxic agents, which involves oxidative stress pathways. To indirectly determine the involvement of oxidative stress in HPβCD-induced ototoxicity, we tested the efficacy of an antioxidant reagent, ebselen, on the extent of inner ear side effects caused by HPβCD. Materials and Methods: Ebselen was applied prior to administration of HPβCD in mice. Auditory brainstem response thresholds and otopathology were assessed one week later. Bilateral effects of the drug treatments also were examined. Results: HPβCD-alone resulted in bilateral, severe, and selective loss of outer hair cells from base to apex with an abrupt transition between lesions and intact areas. Ebselen co-treatment did not ameliorate HPβCD-induced hearing loss or alter the resulting histopathology. Conclusions: The results indirectly suggest that cochlear damage by HPβCD is unrelated to reactive oxygen species formation. However, further research into the mechanism(s) of HPβCD otopathology is necessary.

• Korean Journal of Audiology
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• v.23 no.2
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• pp.69-75
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• 2019

Background and Objectives: The antioxidant ebselen will be able to limit or prevent the ototoxicity arising from 2-hydroxypropyl-β-cyclodextrin (HPβCD). Niemann-Pick Type C (NPC) disease is a disorder of lysosomal storage manifested in sphingolipidosis. Recently, it was noted that experimental use of HPβCD could partially resolve the symptoms in both animals and human patients. Despite its desirable effect, HPβCD can induce hearing loss, which is the only major side effect noted to date. Understanding of the pathophysiology of hearing impairment after administration of HPβCD and further development of preventive methods are essential to reduce the ototoxic side effect. The mechanisms of HPβCD-induced ototoxicity remain unknown, but the resulting pathology bears some resemblance to other ototoxic agents, which involves oxidative stress pathways. To indirectly determine the involvement of oxidative stress in HPβCD-induced ototoxicity, we tested the efficacy of an antioxidant reagent, ebselen, on the extent of inner ear side effects caused by HPβCD. Materials and Methods: Ebselen was applied prior to administration of HPβCD in mice. Auditory brainstem response thresholds and otopathology were assessed one week later. Bilateral effects of the drug treatments also were examined. Results: HPβCD-alone resulted in bilateral, severe, and selective loss of outer hair cells from base to apex with an abrupt transition between lesions and intact areas. Ebselen co-treatment did not ameliorate HPβCD-induced hearing loss or alter the resulting histopathology. Conclusions: The results indirectly suggest that cochlear damage by HPβCD is unrelated to reactive oxygen species formation. However, further research into the mechanism(s) of HPβCD otopathology is necessary.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.1
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• pp.27-35
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• 2015

In this paper, we suggested a RS485 based CSMA/CD protocol that is available in low speed multi-node networks such as industry control communication network and home network etc. The suggested protocol was compared to widely used Master-Slave protocol, Modbus. We modeled realistic control network and showed that the average delay and throughput performance were significantly improved in the different transmission rates.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1493-1494
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• 2011

CdS nanostructure materials have been fabricated in porous anodic aluminum oxide (AAO) template by using chemical bath deposition (CBD). These nanostructure materials had uniform diameters of about 15e200 nm, which correspond to the pore sizes of the templates used, and the length was up to 40 mm. X-ray diffraction (XRD) investigation demonstrates that CdS nanostructure materials were hexagonal polycrystalline in nature. As the pore diameter of AAO templates was enlarged, the preferential orientation of c-axis was improved. From PL analysis, the sulfur-deficient defects at the surfaces of CdS nanostructure materials were increasedwhen the samplewas synthesized in the template with larger pore diameter.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.371-371
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• 2011

본 연구에서는 황화납(PbS)과 황화카드뮴(CdS)을 감응물질로 하는 양자점 감응형 태양전지를 만들고 효율을 측정하였다. Sputter를 이용하여 고진공의 상태에서 산화아연(ZnO) film을 seed layer로 증착한 후 수열합성법으로 ZnO 나노선을 합성한다. 합성된 나노선을 successive ionic layer adsorption and reaction (SILAR) 법으로 PbS, CdS 양자점을 합성하고 이를 주사전자 현미경(SEM), X-선 회절(XRD)을 통해 확인하였다. 또한 PbS와 CdS의 co-sensitizer를 합성하고 diffused reflectance spectra (DRS)를 측정함으로써 넓은 범위의 광흡수도를 확인할 수 있었다. Co-sensitizer의 합성 방법을 달리하여 PbS/CdS를 합성한 후 각각의 효율을 측정해보고, 더 높은 효율을 내기 위한 방안에 대해 고찰하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.113-113
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• 2015

본 연구에서는 thermal evaporation법을 이용하여 제작한 CdTe 후막의 미세구조, 전기적 특성 및 X-선 조사에 따른 특성을 비교분석하였다. 기판온도를 $370{\sim}450^{\circ}C$로 변화시키며 증착하였으며, CdCl2 첨가에 따른 미세구조 변화를 관찰하였다. CdTe 막의 상 하부에 전극을 형성하여 I-V 특성을 평가하고, 실제 X-ray를 샘플에 조사하여 sensitivity를 측정하였다. 박막형성 초기에는 기판온도가 증가함에 따라 grain size가 증가하였지만, grain uniformity는 감소하였다. X-ray 특성향상을 위해서는 grain size와 uniformity 모두 중요한 인자이기 때문에 uniformity 향상을 위해 Cl을 첨가하였다. 미량의 Cl 첨가에서는 큰 변화를 보이지 않았지만 더 많은 양의 Cl 첨가 시, grain size 와 uniformity 모두 증가되는 것을 확인하였으며, 그에 따라 I-V, X-ray 조사 특성 모두 개선되는 것을 확인할 수 있었다.

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.252-253
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• 2005

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.332-333
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• 2004

• Journal of Pharmaceutical Investigation
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• v.25 no.3
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• pp.227-237
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• 1995

Omeprazole(OMP) complexes such as inclusion complexes of OMP with $hydroxypropyl-{\beta}-cyclodextrin$(HPCD) and ${\beta}-cyclodextrin({\beta}-CD)$, OMP-cholestyramine(CHL) and OMP-ethylenediamine(OMP-ED) were prepared, respectively. The partition coefficients in Witepsol H-15 /pH 7.4 phosphate buffer solution of OMP complexes$(OMP-HPCD;\;3.69{\pm}0.26,\;OMP-{\beta}-CD;\;4.08{\pm}0.21,\;OMP-CHL;\;4.36{\pm}0.25\;and\;omeprazole\;sodium(OMP-Na);\;3.64{\pm}0.37)$ were higher than that of OMP $(2.66{\pm}0.47)$. OMP was not completely dissolved until even 3 hrs, but all the OMP complexes studied were released about 100% in 20 min. The rectal suppositories containing OMP or each above OMP complex were prepared using Witepsol H-15 base, and their dissolution and stability were examined, and pharmacokinetic study were investigated after their rectal administrations to the rabbits. While the suppository containing OMP was released only less than 60% in 150 min, $OMP-{\beta}-CD$, OMP-CHL, OMP-Na and OMP-ED suppositories were all released about 65% in 20 min. Especially, OMP-HPCD suppository released OMP about 70% in 10 min. All the additives such as sodium laurylsulfate, eglumine, arginine and PVP increased drug release from OMP-HPCD suppository to some extent. The decomposition rate constants of OMP in the suppositories were $9.117{\times}10^{-3}\;day^{-l}$ for OMP suppository, $2.121{\times}10^{-2}$ for OMP-HPCD, $1.607{\times}10^{-2}$ for $OMP-{\beta}-CD$, $9.26{\times}10^{-3}$ for OMP-Na, $6.769{\times}10^{-3}$ for OMP-CHL and $5.58{\times}10^{-3}\;day^{-l}$ for OMP-ED suppository, respectively. Additives such as arginine, eglumine and ED had some stabilizing effect for OMP-HPCD, OMP-CHL and OMP-Na suppositories, respectively. After 6 month-storage at $30^{\circ}C$, 75% RH, OMP-CHL suppository was most stable. The values of Tmax for OMP-HPCD and OMP-Na suppositories were $11.7{\pm}2.36\;and\;11.4{\pm}2.56\;min$, respectively. The values of Cmax for OMP-HPCD and OMP-CHL suppository were $2.31\;{\mu}g/ml\;(p<0.01)\;and\;1.89\;{\mu}g/ml\;p<0.01)$, respectively. The values of AUC for OMP and $OMP-{\beta}-CD$ suppository were $61.9{\pm}25.79\;and\;68.6{\pm}29.48\;{\mu}g\;{\cdot}\;min/ml$, and the corresponding values for OMP-HPCD and OMP-CHL were $106.1{\pm}43.16\;(p<0.05)\;and\;127.3{\pm}42.52\;{\mu}g\;{\cdot}\;min/ml(p<0.01)$, respectively. The above results indicate the OMP-HPCD and OMP-CHL suppositories have the excellent bioavailabilties in vivo study.