Photocatalytic Activity of Reduced Graphene Oxide-SnSe Nanohybrids with Efficiency Interface Effect

H. Y. He 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.3

Reduced graphene oxide-SnSe (rGO-SnSe) nanohybrids were synthesized with a solution chemical reaction at room temperature. The nanohybrids were characterized by various techniques for their microstructural and photocatalytic activities in photodegradation of alkaline dye malachite green in the water. The effects of rGO/SnSe ratio, initial solution pH, and H2O2 concentration on the photodegradation efficiency were studied. The SnSe nanocrystallines with nanoscale size and narrow bandgap were formed and uniformly adhered on the rGO surface. Raman analysis confirmed the reduction of GO. The experimental results indicated that the nanohybrids showed excellent sunlight-excited photocatalytic activity in degrading malachite green in the water. Significantly, the nanohybrids showed remarkable photo-Fenton-like catalytic activity. The photodegradation rates of the hybrids were greater than that of SnSe nanoparticles, increased with increasing rGO/SnSe ratio, and related to operation parameters. High photocatalytic activities were ascribed to the efficiency interface effect that was confirmed by the calculations of band energy level and photoconductivity. The TOC measurement further verified the photodegradation results. The nanoparticles and nanohybrids also showed excellent reusability.

The Thermal Stability and Elevated Temperature Mechanical Properties of Spray-Deposited $SiC_P$/Al-11.7Fe-1.3V-1.7Si Composite

Hao, L.,He, Y.Q.,Wang, Na,Chen, Z.H.,Chen, Z.G.,Yan, H.G.,Xu, Z.K. The Korean Society for Composite Materials 2009 Advanced composite materials Vol.18 No.4

The thermal stability and elevated temperature mechanical properties of $SiC_P$/Al-11.7Fe-1.3V-1.7Si (Al-11.7Fe-1.3V-1.7Si reinforced with SiC particulates) composites sheets prepared by spray deposition (SD) $\rightarrow$ hot pressing $\rightarrow$ rolling process were investigated. The experimental results showed that the composite possessed high ${\sigma}_b$ (elevated temperature tensile strength), for instance, ${\sigma}_b$ was 315.8 MPa, which was tested at $315^{\circ}C$, meanwhile the figure was 232.6 MPa tested at $400^{\circ}C$, and the elongations were 2.5% and 1.4%, respectively. Furthermore, the composite sheets exhibited excellent thermal stability: the hardness showed no significant decline after annealing at $550^{\circ}C$ for 200 h or at $600^{\circ}C$ for 10 h. The good elevated temperature mechanical properties and excellent thermal stability should mainly be attributed to the formation of spherical ${\alpha}-Al_{12}(Fe,\;V)_3Si$ dispersed phase particulates in the aluminum matrix. Furthermore, the addition of SiC particles into the alloy is another important factor, which the following properties are responsible for. The resultant Si of the reaction between Al matrix and SiC particles diffused into Al matrix can stabilize ${\alpha}-Al_{12}(Fe,\;V)_3Si$ dispersed phase; in addition, the interface (Si layer) improved the wettability of Al/$SiC_P$, hence, elevated the bonding between them. Furthermore, the fine $Al_4C_3$ phase also strengthened the matrix as a dispersion-strengthened phase. Meanwhile, load is transferred from Al matrix to SiC particles, which increased the cooling rate of the melt droplets and improved the solution strengthening and dispersion strengthening.

A facile sol-gel method for synthesis of porous Nd-doped TiO₂ monolith with enhanced photocatalytic activity under UV-Vis irradiation

Du, J.,Chen, H.,Yang, H.,Sang, R.,Qian, Y.,Li, Y.,Zhu, G.,Mao, Y.,He, W.,Kang, D.J. Elsevier 2013 Microporous and mesoporous materials Vol.182 No.-

A porous Nd-doped TiO<SUB>2</SUB> monolith was successfully synthesized with polystyrene spheres as a template using a sol-gel method followed by calcination at high temperature. The porous Nd-doped TiO<SUB>2</SUB> monolith was characterized by X-ray diffractometry, scanning electron microscopy and Brunauer-Emmett-Teller measurements. Nd doping can increase the TiO<SUB>2</SUB> surface area by hindering the growth of large TiO<SUB>2</SUB> particles, and suppressing the recombination of photo-produced hole/electron (h<SUP>+</SUP>/e<SUP>-</SUP>) pairs. Moreover, its porous structure can provide a large surface area, facilitating enhanced adsorption and fast transfer of pollutants. To evaluate the photocatalytic activity of the porous Nd-doped TiO<SUB>2</SUB> monolith, the photo-degradation for methyl orange was investigated under UV-Vis irradiation. The porous 0.5% Nd-doped TiO<SUB>2</SUB> monolith showed better behavior than the other as-prepared samples and Degussa P25 due to its narrow band gap, high efficiency for h<SUP>+</SUP>/e<SUP>-</SUP> pair separation, and large surface area. The synergistic combination of Nd doping and the porous structure is a promising material design strategy for use in the degradation of organic pollutants.

Astrophysically Important 26Si States Studied with the 28Si(4He,6He)26Si Reaction

Y. K. Kwon,이춘식,J. Y. Moon,J. H. Lee,J. Y. Kim,M. K. Cheoun,S. Kubono,H. Yamaguchi,J. J. He,A. Saito,Y. Wakabayashi,H. Fujikawa,G. Amadio,N. Iwasa,K. Inafuku,L. H. Khiem,M. Tanaka,Y. Fuchi,A. A. Chen,S 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2

The emission of a 1.809-MeV γ-ray from the first excited state of 26Mg, followed by β-decay of 26Al in its ground state (denoted as 26Alg.s.), has been identied by several gamma-ray telescopes. To resolve the controversy over the possible sources of the observational 1.809-MeV γ-rays, one needs accurate knowledge of the production rate of 26Alg.s.. The 25Al(p,γ)26Si reaction is one of the most important astrophysical reactions to be investigated, but its rate is uncertain due to the lack of level information on 26Si above the proton threshold (Qpγ = 5.518 MeV). Illiadis et al. suggested that the 25Al(p,γ)26Si reaction should be dominated by a 3+ unnatural parity state at Ex = 5970 keV. Recent studies proposed several states as candidates for the 3+ states. However, the spin-parity assignments for these states are still uncertain. In the present work, we measured the 28Si(4He,6He)26Si reaction at 120 MeV to confirm the unnatural parity states just above the proton threshold. The measurement was performed with the high-resolution particle analyzer at the Center for Nuclear Study, University of Tokyo. We observed a total of 22 excited states in 26Si. The 7018-keV level, which was only observed by Bardayan et al. with the 28Si(p; t)26Si reaction, was confirmed in our measurement. Among the candidates of unnatural parity states at Ex = 5678, 5916, and 5945 keV, the 5918-keV state was only observed within the error of the excitation energy. A new state at Ex = 6101 keV was also identified.

PLS Preinjector Linac Vacuum System

Y. K. Kim,J. S. Bak,M. H. Cho,W. Namkung,H. S. Oh,Y. B. Kwon,F. He,H. J. Yang,H. F. Chen 한국진공학회 1992 한국진공학회 학술발표회초록집 Vol.- No.-

δ-catenin overexpression promotes angiogenic potential of CWR22Rv-1 prostate cancer cells via HIF-1α and VEGF

He, Y.,Kim, H.,Ryu, T.,Kang, Y.,Kim, J.A.,Kim, B.H.,Lee, J.H.,Kang, K.,Lu, Q.,Kim, K. North-Holland Pub ; Elsevier Science Ltd 2013 FEBS letters Vol.587 No.2

This study revealed that CWR22Rv-1 cells overexpressing δ-catenin display bigger tumor formation and higher angiogenic potentials than their matched control cells in the CAM assay. In addition, δ-catenin overexpression in CWR22Rv-1 cells results in increased hypoxia-inducible factor 1-alpha (HIF-1α and vascular endothelial growth factor (VEGF) expression. Furthermore, δ-catenin overexpression was found to enhance nuclear distribution of both β-catenin and HIF-1α in hypoxic condition, which is diminished by knockdown of δ-catenin. Our current study adds novel evidence regarding contribution of δ-catenin to the progression of prostate cancer.

Tribological behavior of a 20CrMo alloy implanted with nitrogen ions by plasma source ion implantation

He, H.B.,Li, H.Y.,Lyu, S.K. Elsevier Sequoia [etc.] 2010 Wear: An international journal on the science and Vol.268 No.3

A 20CrMo alloy was implanted with nitrogen ions using plasma source ion implantation (PSII), at a dose range of 1.0x10<SUP>17</SUP> to 6.0x10<SUP>17</SUP>ionscm<SUP>-2</SUP>. Electron Probe Micro-Analysis (EPMA) was used to investigate the depth profile of the implanted layer. Friction and wear tests were carried out on a multi-purpose wear tester. Scanning electron microscopy (SEM) was used to observe the micro-morphology of the worn surface. The results revealed that after being implanted with nitrogen ions, the friction coefficient of the surface layer decreased, and the wear resistance increased with the nitrogen dose. The tribological mechanism was mainly adhesive, and the adhesive wear tended to become weaker oxidative wear with the increase of the nitrogen dose. The effects were mainly attributed to the formation of a hard nitride precipitate and a supersaturated solid solution of nitrogen in the surface layer.

Synthesis and magnetic properties of BaAl4Fe8O19 powders fabricated by a microemulsion method

H. Y. He,Z. He,Q. Shen 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.5

Al-substituted M-type hexaferrite is a high anisotropy ferromagnetic material. In this paper, we report the synthesis and characterization of BaAl4Fe8O19 powders from two microemulsion systems of po1yoxyethylene octylphenol ether/1, 2-propylene glycol or ethanol/cyclohexane/water and cetrimonium bromide/1, 2-propylene glycol/cyclohexane/water. Two microemulsion systems were found to give wide stable regions. The synthesized powders were characterized with X-ray diffraction, scanning electron microscopy and a vibrating sample magnetometer. The experimental results indicated that the surfactant, co-surfactant,and oil/water ratio remarkably affected the particle size, size distribution, anisotropy and magnetic properties of the powders. The powder prepared with the microemulsion of po1yoxyethylene octylphenol ether/1, 2-propylene glycol/cyclohexane/water exhibited the best particle characters, that is, a uniform thin particle morphology, a large shape anisotropy, a small particle size, a large coercivity of 8734.16 Oe, and a saturation magnetization of 20.821 emu/g.

Microstructural and magnetic property of Co1-xZnxFe2O4 nanoparticles synthesized by the hydrothermal method

H. Y. He 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.3

The cobalt zinc ferrite (Co1-xZnxFe2O4 x = 01.0) nanoparticles were synthesized by a hydrothermal method. Effects of zinc content and synthesis time on the microstructure and magnetic property of the nanoparticles were studied. The experimental results indicated that Zn2+ substitution for Co2+ and different synthesis time lead to obvious changes in microstructure and magnetic property of the ferrites. The saturation magnetization of the nanoparticles showed maximal value for the Zn content x = 0.2 and overall increased as increasing synthesis time form 12 hrs to 24 hrs. The residual magnetization, the coercivity and anisotropy constant had similar variation trends with shape anisotropy as varying Zn content.

Enhanced delivery of T cells to tumor after chemotherapy using membrane-anchored, apoptosis-targeted peptide

He, X.,Bonaparte, N.,Kim, S.,Acharya, B.,Lee, J.Y.,Chi, L.,Lee, H.J.,Paik, Y.K.,Moon, P.G.,Baek, M.C.,Lee, E.K.,Kim, J.H.,Kim, I.S.,Lee, B.H. Elsevier Science Publishers 2012 Journal of controlled release Vol.162 No.3

Chemotherapy-induced apoptosis of tumor cells enhances the antigen presentation and sensitizes tumor cells to T cell-mediated cytotoxicity. Here we harnessed the apoptosis of tumor cells as a homing signal for the delivery of T cells to tumor. Jurkat T cells were anchored with ApoPep-1, an apoptosis-targeted peptide ligand, using the biocompatible anchor for membrane (BAM), an oleyl acid derivative. The ApoPep-1-BAM conjugate was efficiently anchored to cell membrane, while little anchoring was obtained with ApoPep-1 alone. The retention period of the ApoPep-1-BAM conjugate on cell membrane was approximately 80 and 40min in the absence and presence of serum, respectively. ApoPep-1 was resistant to degradation in serum until 2h. The apoptosis-targeted T cells that were anchored with the ApoPep-1-BAM preferentially bound to apoptotic tumor cells over living cells. When intravenously injected into tumor-bearing mice, the number of apoptosis-targeted T cells and in vivo fluorescence signals by the homing of the cells to doxorubicin-treated tumor were higher than those of untargeted T cells. Accumulation of apoptosis-targeted T cells at other organs such as liver was not detected. These results suggest that the chemotherapy-induced apoptosis and subsequent enhancement of T cell delivery to tumor by the membrane anchoring of the apoptosis-targeted peptide could be a novel strategy for cancer immunotherapy.