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Optimal synthesis of antimony-doped cuprous oxides for photoelectrochemical applications
Yun, Young Dae,Baek, Seung Ki,Kim, Joo Sung,Kim, Young Been,Jung, Sung Hyeon,Kim, Yunseok,Cho, Hyung Koun Elsevier 2019 THIN SOLID FILMS - Vol.671 No.-
<P><B>Abstract</B></P> <P>We investigated the influence of Sb dopant concentration on the structural, electrical, and photoelectrochemical properties of the photocathode cuprous oxide (Cu<SUB>2</SUB>O) thin films. The photoabsorber p-type Cu<SUB>2</SUB>O films were prepared by electrodeposition in ionic electrolytes including copper sulfate and antimony sulfate at 333 K and pH = 10. The small amount of Sb doping contributes to the fast Cu ion transport to the substrate and ion consumption; consequently, the p-type Cu<SUB>2</SUB>O with high crystalline quality can be reproducibly synthesized with high electrical stability. Among the various samples, the mole fraction of c(Sb)/[c(Cu) + c(Sb)] = 0.75 mol% exhibits the best electrical resistivity and improved transparency in the infrared region, which is involved with the fast overlap of the nuclei crystals under 5 nm from the high nuclei density. Additionally, the post-thermal annealed Sb-doped Cu<SUB>2</SUB>O sample reveals an enhanced photocurrent of ~0.65 mA/cm<SUP>2</SUP> vs. RHE (reversible hydrogen electrode) without metal catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sb added electrodeposition of Cu<SUB>2</SUB>O (cuprous oxide) films were electrodeposited. </LI> <LI> Best Sb concentration on the Cu<SUB>2</SUB>O was determined. </LI> <LI> Sb contents affected the photoelectrochemical characteristics of the films. </LI> <LI> Post annealing process improved the absorbance and electrical conductivity. </LI> </UL> </P>
Yun-Sung Lee,Miseon Shim,Ga-Young Choi,Sang Ho Kim,Wansu Lim,Jin-Woo Jeong,Young-Jin Jung,Han-Jeong Hwang 대한의용생체공학회 2023 Biomedical Engineering Letters (BMEL) Vol.13 No.3
Recently, we introduced a current limiter-based novel transcranial direct-current stimulation (tDCS) device that does notgenerate significant tDCS-induced electrical artifacts, thereby facilitating simultaneous electroencephalography (EEG)measurement during tDCS application. In this study, we investigated the neuromodulatory effect of the tDCS device usingresting-state EEG data measured during tDCS application in terms of EEG power spectral densities (PSD) and brainnetwork indices (clustering coefficient and path length). Resting-state EEG data were recorded from 10 healthy subjects during both eyes-open (EO) and eyes-closed (EC)states for each of five different conditions (baseline, sham, post-sham, tDCS, and post-tDCS). In the tDCS condition,tDCS was applied for 12 min with a current intensity of 1.5 mA, whereas tDCS was applied only for the first 30 s in thesham condition. EEG PSD and brain network indices were computed for the alpha frequency band most closely associatedwith resting-state EEG. Both alpha PSD and network indices were found to significantly increase during and after tDCS application comparedto those of the baseline condition in the EO state, but not in the EC state owing to the ceiling effect. Our resultsdemonstrate the neuromodulatory effect of the tDCS device that does not generate significant tDCS-induced electricalartifacts, thereby allowing simultaneous measurement of electrical brain activity. We expect our novel tDCS device to be practically useful in exploring the impact of tDCS on neuromodulation moreprecisely using ongoing EEG data simultaneously measured during tDCS application.
Expression of Nm23 in gliomas and its effect on migration and invasion in vitro.
Jung, Shin,Paek, Yun-Woong,Moon, Kyung-Sub,Wee, Sung-Chan,Ryu, Hyang-Hwa,Jeong, Young-Il,Sun, Heung-Suk,Jin, Yong-Hao,Kim, Kyung-Keun,Ahn, Kyu-Youn Potamitis Press 2006 Anticancer research Vol. No.
<P>BACKGROUND: Despite the well-documented importance of Nm23 in the control of metastasis, there is currently a paucity of data regarding the role of this gene family in the control of glioma invasion. MATERIALS AND METHODS: Nm23-H1 expression in gliomas was assessed via immunohistochemistry, Western blot, RT-PCR and Northern blot analyses. The migration and invasion ability were also investigated in primary glioma culture cells, human glioma cell lines and nm23-H1 transfectant, using an in vitro brain slice invasion model and a simple scratch technique. RESULTS: Although no significant correlations were detected between nm23-H1 expression and pathological grade, the endogenous nm23-H1 expression in gliomas was found to be inversely correlated with their migratory abilities. Additionally, the nm23-H1 transfectant resulted in a reduction of approximately 45% of the migratory ability and suppressed the invasiveness of the parental cell line. CONCLUSION: Our overall findings suggest that nm23-H1 may play an important role in the suppression of glioma invasion and migration.</P>
Scandium(III) Triflate-Catalyzed Coumarin Synthesis
Jung, Keumnyeo,Park, Yun-Jeong,Ryu, Jae-Sang Taylor Francis 2008 Synthetic communications Vol.38 No.24
<P> Scandium(III) triflate is an excellent catalyst in the von Pechmann condensation. The solvent-free catalytic reactions proceed smoothly with a range of phenols and &bgr;-ketoesters in the presence of 10 mol% scandium(III) triflate at 80 °C. This simple method affords various 4-substituted coumarins in good to excellent yield and is superior to the classical method in several aspects: solvent-free conditions, short reaction times, a decreased catalyst loading, a mild reaction temperature, and an easy workup.</P>
Yun, J.C.,Jung, S.S.,Lee, Jung Goo,Choi, C.J.,Lee, Jai Sung Trans Tech Publications, Ltd. 2010 Materials science forum Vol.638 No.-
<P>The present investigation attempted to optimize the R-D (reduction-diffusion) process for fabricating Sm2Fe17 nanoscale powder from ball-milled powders of samarium oxide and iron oxide using a solid reducing agent of calcium hydrides (CaH2). It was found that the target alloy phase of Sm2Fe17 can be produced by controlling the gas atmosphere in the process of powder preparation to R-D reaction. Powder handling of CaH2 in a protective atmosphere is essential to avoid the formation of Ca(OH)2 which suppresses calcium formation. A switching gas atmosphere of H2 to Ar-H2 during the R-D process at 350oC resulted in a reduction of Fe2O3 and alloying of Sm-Fe, consequently forming nanocrystalline Sm2Fe17.</P>
Sung-Hee Son,윤제정,Gwang-Chae Oh,Sang-Yun Jung,V. I. Adamovich,A. V. Kuhta,한은미 한국물리학회 2005 Current Applied Physics Vol.5 No.1
Green-emitting biphenyl derivative with benzoxazole (4,40-bis[2-(1,3-benzoxazol-yl-1-ethenyl)]-2-hexyloxybiphenyl) was newlysynthesized. The benzoxazole, due to its electron-rich and good thermal stability, is introduced to enhance organic light-emittingdiodes(OLEDs). This paper reports the optical and electrical characteristics by utilizing new biphenyl derivative with benzoxazole asthe emitting layer for OLEDs. According to Thermogravimetric Analyzer (TGA) analysis, the weight ratio of that biphenylderivative with benzoxazole starts to decrease at 350.C, which suggests relatively good thermal property. The structure of the deviceis ITO/TPD ora-NPD (50 nm)/biphenyl derivative (50 nm)/LiF (0.5 nm)/Al (150 nm). The maximum luminance of the device usinga-NPD is about 74,700 nW/cm2 at 9.6 V. With increase of applied voltage, the emitting zone changes from green to blue due to theinuence of emission froma-NPD. On the other hand, the device based on TPD is 217,900 nW/cm2 at 6.4 V and the emitting zone ofthe device is constant regardless of the driving voltage.
Jung, Jin Su,Kim, Jae Hoon,Kim, Min Seok,Jeong, Han Mo,Kim, Yong Sung,Kim, Tae Kyoon,Hwang, Jeong Mi,Lee, Sang Yun,Cho, Yang Lae Wiley Subscription Services, Inc., A Wiley Company 2008 Journal of applied polymer science Vol.109 No.3
<P>The properties of reactive hot melt polyurethane adhesives (RHAs) modified by dihydroxyl-terminated reactive acrylic macromonomers were examined and compared with those of RHAs modified with a nonreactive commercial acrylic copolymer. The melt viscosity and initial bond strength was increased when a portion of the polyols and tackifier was replaced by macromonomers or acrylic copolymers, which have higher glass transition temperatures. When RHA was modified by macromonomer, the storage modulus at low shear rate was reduced and set time was increased, which suggests that the chain entanglement was diminished by short-chain branches created by the macromonomers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008</P>