• 한국표면공학회지
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• 제48권6호
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• pp.303-308
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• 2015

Pd-functionalized ${\beta}-Bi_2O_3$ nanowires are synthesized by thermal evaporation of Bi powder using VLS mechanism followed by Pd coating and annealing. In this study, sensing properties of Pd-functionalized ${\beta}-Bi_2O_3$ nanowires sensor to selected concentrations of $NO_2$ gas were examined. Scanning electron microscopy showed that the nanowires with diameters in a range of 100 - 200 nm and lengths of up to a few tens of micrometers. Transmission electron microscopy and X-ray diffraction confirmed that the products corresponded to the nanowires of ${\beta}-Bi_2O_3$ crystals and Pd nanoparticles. Pd-functionalized ${\beta}-Bi_2O_3$ nanowires sensor showed an enhanced sensing performance to $NO_2$ gas compared to as-synthesized ${\beta}-Bi_2O_3$ nanowires sensor. As synthesized and Pd-functionalized ${\beta}-Bi_2O_3$ nanowire sensors showed responses of 178% - 338% and 196% - 535% at $300^{\circ}C$, respectively, to 0.05 - 2 ppm $NO_2$. In addition, the underlying mechanism of the enhancement of the sensing properties of ${\beta}-Bi_2O_3$ nanowires by Pd-functionalization is discussed.

• 한국재료학회지
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• 제19권4호
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• pp.192-197
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• 2009

Carbon nanotubes (CNT) were used as a catalyst support where catalytically active Pd and Pt metal particles decorated the outside of the external CNT walls. In this study, Pd and Pt nanoparticles supported on $HNO_3$-treated CNT were prepared by microwave-assisted heating of the polyol process using $PdCl_2$ and $H_2PtCl_6{\codt}6H_2O$ precursors, respectively, and were then characterized by SEM, TEM, and Raman. Raman spectroscopy showed that the acid treated CNT had a higher intensity ratio of $I_D/I_G$ compared to that of non-treated CNT, indicating the formation of defects or functional groups on CNT after chemical oxidation. Microwave irradiation for total two minutes resulted in the formation of Pd and Pt nanoparticles on the acid treated CNT. The sizes of Pd and Pt nanoparticles were found to be less than 10 nm and 3 nm, respectively. Furthermore, the $SnO_2$ films doped with CNT decorated by Pd and Pt nanoparticles were prepared, and then the $NO_2$ gas response of these sensor films was evaluated under $1{\sim}5\;ppm$ $NO_2$ concentration at $200^{\circ}C$. It was found that the sensing property of the $SnO_2$ film sensor on $NO_2$ gas was greatly improved by the addition of CNT-supported Pd and Pt nanoparticles.

• 한국재료학회지
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• 제15권4호
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• pp.281-284
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• 2005

Room and high temperature deformation behaviors of Cu-Zr-Ti-Pd bulk metallic glasses produced by copper mold casting were investigated. The addition of Pd was shown to enhance the glass forming ability and thermal stability of Cu-Zr-Ti base bulk metallic glass. The compressive strength of $Cu_{55}Zr_{30}Ti_{10}Pd_5$ bulk metallic glass was 2230 MPa with 1.8 plastic strain. The stress overshoot and yield drop phenomenon were observed below $487^{\circ}C$ and a drastic decrease in the flow stress was observed at $487^{\circ}C$. The stress overshoot is thought to be associated with stress-induced structural relaxation.

• 한국표면공학회지
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• 제23권2호
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• pp.30-38
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• 1990

For the purpose of suggesting the thermal resistant catalyst for automobile emission control, various catalysts, Pd-WO3 and PD-La2O3 systems, were charactrized before and after thermal aging. It was found that La2O3 formed amorphous surface compound on the support by strong metal-support interaction(SMSI). And by Temperature Programmed Desorption (TPD) expeiment, it was found that the distribution of acid site which is strong acid sites by adding the promoters. After thermal aging, it was observed that the acidity of Pd-WO3 system was decreased largely because of losing acid site by metal vaporization. On the other hand, there was pretty small change in the properties of matter of Pd-La2O3 system. Therefore, it could be considered that La2O3 formed heat resisting amorphous surface compound on the support by SMSI.

• Biomolecules & Therapeutics
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• 제30권5호
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• pp.409-417
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• 2022

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide, and accumulating evidence indicates that mitochondrial dysfunction is associated with progressive deterioration in PD patients. Previous studies have shown that sinapic acid has a neuroprotective effect, but its mechanisms of action remain unclear. The neuroprotective effect of sinapic acid was assayed in a PD mouse model generated by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as well as in SH-SY5Y cells. Target protein expression was detected by western blotting. Sinapic acid treatment attenuated the behavioral defects and loss of dopaminergic neurons in the PD models. Sinapic acid also improved mitochondrial function in the PD models. MPTP treatment increased the abundance of mitochondrial fission proteins such as dynamin-related protein 1 (Drp1) and phospho-Drp1 Ser616. In addition, MPTP decreased the expression of the REV-ERB α protein. These changes were attenuated by sinapic acid treatment. We used the pharmacological REV-ERB α inhibitor SR8278 to confirmation of protective effect of sinapic acid. Treatment of SR8278 with sinapic acid reversed the protein expression of phospho-Drp1 Ser616 and REV-ERB α on MPTP-treated mice. Our findings demonstrated that sinapic acid protects against MPTP-induced PD and these effects might be related to the inhibiting abnormal mitochondrial fission through REV-ERB α.

• 대한의생명과학회지
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• 제29권3호
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• pp.121-129
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• 2023

Parkinson's disease (PD) is a progressive neurodegenerative disorder that affects millions of people worldwide. The conventional treatment model for PD have harmful side effects, such as dyskinesia, hallucinations, nausea, and fatigue, and are expensive. As a result, natural products derived from medicinal herbs, fruits, and vegetables have emerged as potential therapeutic strategies for PD. These natural products have been traditionally used to treat various diseases and have been shown to possess anti-oxidative and anti-inflammatory properties, as well as inhibitory roles in protein misfolding, mitochondrial homeostasis, neuroinflammation and other neuroprotective processes. In addition, they have fewer side effects and are generally less expensive than conventional drugs. It also discusses the limitations of current treatments and the potential of natural remedies derived from plants to treat PD in new ways or as supplements to existing treatments. The multifunctional mechanisms of medicinal plants that may be utilized to treat PD are also discussed, including the modulation of neurotransmitter systems, the enhancement of neurotrophic factors, and the inhibition of apoptosis. While more research is needed to fully understand their mechanisms of action and efficacy, natural products have the potential to provide safer and more effective treatment options for patients with PD.

• 한국임상수의학회지
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• 제30권1호
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• pp.5-11
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• 2013

급성 위궤양은 위점막에서 세포증식과 세포사멸의 불균형으로 발병되어진다. 현재 Platycodin D (PD)는 항산화 및 항염증 등의 다양한 약리효능을 가진다고 보고되고 있다. 본 실험은 ibuprofen에 의해 유발된 급성 위궤양이 전처치한 PD에 의해 위궤양 보호효과를 가지는 가를 알아보기 위해 실시하였다. PD의 효능은 위점막에서의 COX-2의 발현과 더불어 위점막상피세포의 증생과 세포사멸정도에 의해서 평가하였다. 실험군은 정상대조군, ibuprofen 유발 위궤양군, 2.5 mg/kg PD 전처치군, 5 mg/kg PD 전처치군으로 분류하였다. 급성위궤양은 200 mg/kg의 ibuprofen을 하루에 3번 8시간 간격으로 경구 투여하여 유발하였다. PD는 5일간 경구로 하루에 한 번씩 전처치하였다. PD의 전처치가 ibuprofen에 의해 유발된 위궤양 병변을 유의적으로 감소시켰으며 과도한 위점액 분비로 인한 점액질의 소실을 억제하였다. 또한 PD 전처치가 위점막의 상피세포증식층에서 Ki-67 양성세포의 감소 및 세포사멸을 억제하였다. 추가적으로 PD의 전처치가 위궤양에 의해 증가된 COX-2 발현을 감소시켰다. 이상의 연구결과는 PD의 전처치가 ibuprofen에 의해 유발된 위점막손상에 있어 COX-2의 발현조절을 통하여 위점막세포의 증식과 사멸에 관여할 것으로 보여진다.

• 전기학회논문지
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• 제61권2호
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• pp.251-256
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• 2012

This study deals with the location of partial discharges(PDs) for power cables and GIS using 2 PD sensors and long coaxial signal cables. Throughout the experiments by use of simulated PD pulses and corona discharges in the power cable system, it is found out that the impedance matching between the coaxial signal cable and the measuring equipment should be done for good S/N ratio and the on-site measurement using more than 100m-long coaxial signal cable is possible. In addition, new PD location algorithm with the polarities of PD pulses and the arrival time difference between two pulses was proposed and was proved through the partial discharge experiments for the cable joint defect and artificial void defect.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권1호
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• pp.1-4
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• 2004

This paper presents an investigation of the phase-resolved partial discharge (PD) pattern of PET (Poly Ethylene Telephthalate) films with carbon black particles. The phase-resolved PD pattern and statistical parameter from PET samples according to the number of included semiconductor particles were measured. The measurement system consisted of a conventional PD detector using a digital signal processing technique. The partial discharge patterns of the PET films that include the semiconductor particles were investigated to simulate an actual situation that may exist in the cable. In addition, difference of PD patterns between semiconducting particles in PET films and artificial voids was studied. The relationship between the numbers of semiconductor particles in PET films was discussed through the difference of Ψ-q-n distribution and statistical analysis.

• 한국결정성장학회지
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• 제6권3호
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• pp.415-423
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• 1996

황산니켈염 수용액에서 가압수소환원법을 이용하여 알루미나 분말상에 니켈 코팅층을 형성하기 위하여 실험조건(수소분압, 반응온도, $PdCl_{2}$ 첨가량, 알루미나의 종류 및 입도)을 변화시키면서 니켈이온의 환원속도 및 석출상태를 조사하였다. 환원온도 $165^{\circ}C$, 수소분압 300 psi, 코팅촉매제 $PdCl_{2}\;2\;mg/\ell$를 첨가한 조건에서 균질한 니켈코팅층을 얻을 수 있었다.