A Deep Investigation of the Thermal Decomposition Process of Supported Silver Catalysts

Jun Jiang,Tianhao Xu,Yaping Li,Xiaodong Lei,Hui Zhang,D. G. Evans,Xiaoming Sun,Xue Duan 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.6

A deep understanding of the metallic silver catalysts formation process on oxide support and the formation mechanism is of great scientific and practical meaning for exploring better catalyst preparing procedures. Herein the thermal decomposition process of supported silver catalyst with silver oxalate as the silver precursor in the presence of ethylenediamine and ethanolamine is carefully investigated by employing a variety of characterization techniques including thermal analysis, in situ diffuse reflectance infrared Fourier transform spectroscopy, scanning electron microscopy, and X-ray diffraction. The formation mechanism of supported silver particles was revealed. Results showed that formation of metallic silver begins at about 100 oC and activation process is essentially complete below 145 oC. Formation of silver was accompanied by decomposition of oxalate group and removal of organic amines. Catalytic performance tests using the epoxidation of ethylene as a probe reaction showed that rapid activation (for 5 minutes) at a relatively low temperature (170 oC) afforded materials with optimum catalytic performance, since higher activation temperatures and/or longer activation times resulted in sintering of the silver particles.

Influence of the precipitated phases in Al-4%Cu alloys processed in the high magnetic field and cryogenic treatment

Jiang Jun,Qi Min,Won-Jo Park 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Transformation of materials under high magnetic field is much different compared with conventional condition. There is big significant in materials science investigating transformation behavior of materials under high magnetic field. Aluminium copper alloys are one kind of typical precipitation hardening alloy which has been widely used in industry. It is interesting to investigate transformation behavior of such kind of alloys under high magnetic field. The author prepared the Al-4%Cu alloy using crucible electrical resistance furnace in order to further the research of the Al-Cu binary alloy. The analysis techniques such as optical microscopy (OM), Vickers micro-hardness, and X-ray diffraction and transmission electron microscopy (TEM) were employed in this dissertation. Firstly the Al-4%Cu alloys which annealed at 180 ℃ are briefly studies. Then the precipitating behavior of second phases in specimens that aged with and without high magnetic field and through cryogenic treatment were analyzed and discussed mainly based on the comparison of experimental results of Vickers micro-hardness testing and XRD analysis respectively.

A Deep Investigation of the Thermal Decomposition Process of Supported Silver Catalysts

Jiang, Jun,Xu, Tianhao,Li, Yaping,Lei, Xiaodong,Zhang, Hui,Evans, D.G.,Sun, Xiaoming,Duan, Xue Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.6

A deep understanding of the metallic silver catalysts formation process on oxide support and the formation mechanism is of great scientific and practical meaning for exploring better catalyst preparing procedures. Herein the thermal decomposition process of supported silver catalyst with silver oxalate as the silver precursor in the presence of ethylenediamine and ethanolamine is carefully investigated by employing a variety of characterization techniques including thermal analysis, in situ diffuse reflectance infrared Fourier transform spectroscopy, scanning electron microscopy, and X-ray diffraction. The formation mechanism of supported silver particles was revealed. Results showed that formation of metallic silver begins at about $100^{\circ}C$ and activation process is essentially complete below $145^{\circ}C$. Formation of silver was accompanied by decomposition of oxalate group and removal of organic amines. Catalytic performance tests using the epoxidation of ethylene as a probe reaction showed that rapid activation (for 5 minutes) at a relatively low temperature ($170^{\circ}C$) afforded materials with optimum catalytic performance, since higher activation temperatures and/or longer activation times resulted in sintering of the silver particles.

A New Spongilipid from the Freshwater Sponge Spongilla lacustris

Jiang-Miao Hu,You-Xing Zhao,Ji-Jun Chen,Ze-Hong Miao,Jun Zhou 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.5

Temporary formation of highly conducting domain walls for non-destructive read-out of ferroelectric domain-wall resistance switching memories

Jiang, Jun,Bai, Zi Long,Chen, Zhi Hui,He, Long,Zhang, David Wei,Zhang, Qing Hua,Shi, Jin An,Park, Min Hyuk,Scott, James F.,Hwang, Cheol Seong,Jiang, An Quan Nature Publishing Group, a division of Macmillan P 2018 NATURE MATERIALS Vol.17 No.1

Erasable conductive domain walls in insulating ferroelectric thin films can be used for non-destructive electrical read-out of the polarization states in ferroelectric memories. Still, the domain-wall currents extracted by these devices have not yet reached the intensity and stability required to drive read-out circuits operating at high speeds. This study demonstrated non-destructive read-out of digital data stored using specific domain-wall configurations in epitaxial BiFeO<SUB>3</SUB> thin films formed in mesa-geometry structures. Partially switched domains, which enable the formation of conductive walls during the read operation, spontaneously retract when the read voltage is removed, reducing the accumulation of mobile defects at the domain walls and potentially improving the device stability. Three-terminal memory devices produced 14 nA read currents at an operating voltage of 5 V, and operated up to T = 85 °C. The gap length can also be smaller than the film thickness, allowing the realization of ferroelectric memories with device dimensions far below 100 nm.

Human Liver Specific Transcriptional Factor TCP10L Binds to MAD4

Jiang, Dao-Jun,Yu, Hong-Xiu,Hexige, Sa-Yin,Guo, Ze-Kun,Wang, Xiang,Ma, Li-Jie,Chen, Zheng,Zhao, Shou-Yuan,Yu, Long Korean Society for Biochemistry and Molecular Biol 2004 Journal of biochemistry and molecular biology Vol.37 No.4

A human gene T-complex protein 10 like (TCP10L) was cloned in our lab. A previous study showed that it expressed specifically in the liver and testis. A transcription experiment revealed that TCP10L was a transcription factor with transcription inhibition activity. In this study, the human MAD4 was identified to interact with TCP10L by a yeast two-hybrid screen. This finding was confirmed by immunoprecipitation and subcellular localization experiments. As MAD4 is a member of the MAD family, which antagonizes the functions of MYC and promotes cell differentiation, the biological function of the interaction between TCP10L and MAD4 may be to maintain the differentiation state in liver cells. Also, we propose that the up-regulation of Myc is caused by the down-regulation of TCP10L in human hepatocarcinomas.

Increased Serotonin Signaling Contributes to the Warburg Effect in Pancreatic Tumor Cells Under Metabolic Stress and Promotes Growth of Pancreatic Tumors in Mice

Jiang, Shu-Heng,Li, Jun,Dong, Fang-Yuan,Yang, Jian-Yu,Liu, De-Jun,Yang, Xiao-Mei,Wang, Ya-Hui,Yang, Min-Wei,Fu, Xue-Liang,Zhang, Xiao-Xin,Li, Qing,Pang, Xiu-Feng,Huo, Yan-Miao,Li, Jiao,Zhang, Jun-Feng Elsevier 2017 Gastroenterology Vol.153 No.1

<P><B>Background & Aims</B></P> <P>Desmoplasia and poor vascularity cause severe metabolic stress in pancreatic ductal adenocarcinomas (PDACs). Serotonin (5-HT) is a neuromodulator with neurotransmitter and neuroendocrine functions that contributes to tumorigenesis. We investigated the role of 5-HT signaling in the growth of pancreatic tumors.</P> <P><B>Methods</B></P> <P>We measured the levels of proteins that regulate 5-HT synthesis, packaging, and degradation in pancreata from Kras<SUP>G12D/+</SUP>/Trp53<SUP>R172H/+</SUP>/Pdx1-Cre (KPC) mice, which develop pancreatic tumors, as well as in PDAC cell lines and a tissue microarray containing 81 human PDAC samples. We also analyzed expression levels of proteins involved in 5-HT synthesis and degradation by immunohistochemical analysis of a tissue microarray containing 311 PDAC specimens, and associated expression levels with patient survival times. 5-HT level in 14 matched PDAC tumor and non-tumor tissues were analyzed by ELISA. PDAC cell lines were incubated with 5-HT and cell survival and apoptosis were measured. We analyzed expression of the 5-HT receptor HTR2B in PDAC cells and effects of receptor agonists and antagonists, as well as HTR2B knockdown with small hairpin RNAs. We determined the effects of 5-HT stimulation on gene expression profiles of BxPC-3 cells. Regulation of glycolysis by 5-HT signaling via HTR2B was assessed by immunofluorescence and immunoprecipitation analyses, as well as by determination of the extracellular acid ratio, glucose consumption, and lactate production. Primary PDACs, with or without exposure to SB204741 (a selective antagonist of HTR2B), were grown as xenograft tumors in mice, and SB204741 was administered to tumor-bearing KPC mice; tumor growth and metabolism were measured by imaging analyses.</P> <P><B>Results</B></P> <P>In immunohistochemical analysis of a tissue microarray of PDAC specimens, increased levels of TPH1 and decreased level of MAOA, which regulate 5-HT synthesis and degradation, correlated with stage and size of PDACs and shorter patient survival time. We found levels of 5-HT to be increased in human PDAC tissues compared with non-tumor pancreatic tissues, and PDAC cell lines compared with non-transformed pancreatic cells. Incubation of PDAC cell lines with 5-HT increased proliferation and prevented apoptosis. Agonists of HTR2B, but not other 5-HT receptors, promoted proliferation and prevented apoptosis of PDAC cells. Knockdown of HTR2B in PDAC cells, or incubation of cells with HTR2B inhibitors, reduced their growth as xenograft tumors in mice. We observed a correlation between 5-HT and glycolytic flux in PDAC cells; levels of metabolic enzymes involved in glycolysis, the phosphate pentose pathway, and hexosamine biosynthesis pathway increased significantly in PDAC cells following 5-HT stimulation. 5-HT stimulation led to formation of the HTR2B–LYN–p85 complex, which increased PI3K–Akt–mTOR signaling and the Warburg effect by increasing protein levels of MYC and HIF1A. Administration of SB204741 to KPC mice slowed growth and metabolism of established pancreatic tumors and prolonged survival of the mice.</P> <P><B>Conclusions</B></P> <P>Human PDACs have increased levels of 5-HT, and PDAC cells increase expression of its receptor, HTR2B. These increases allow for tumor glycolysis under metabolic stress and promote growth of pancreatic tumors and PDAC xenograft tumors in mice.</P>

Mitigative effects of PFF-A isolated from Ecklonia cava on pigmentation in a zebrafish model and melanogenesis in B16F10 cells

Jun-Geon Je,Yunfei Jiang,Jun-Ho Heo,Xining Li,You-Jin Jeon,Bo-Mi Ryu 한국수산과학회 양식분과 2022 한국수산과학회 양식분과 학술대회 Vol.2022 No.5

First-principles study on the electronic structure and optical properties of La0.75Sr0.25MnO3-σ materials with oxygen vacancies defects

Jun Jiang,Qing-Ming Chen,Xiang Liu 한국물리학회 2018 Current Applied Physics Vol.18 No.2

The electronic structure and optical properties of La0.75Sr0.25MnO3-σ (LSMO3-σ) materials with 1 × 1 × 4 orthorhombic perovskite structure were performed by first-principles calculation. The structural changing of LSMO3 (ideal structure, σ = 0) was not obvious under generalized gradient approximation (GGA) and GGA + U arithmetic. On the contrary, the structural changing of LSMO3-σ (σ = 0.25, with oxygen vacancies defects in the z = 0, c/8, c/6, c/4, and c/2) with GGA + U were more obvious than the result of ideal. This structural distortion induced distinct changing in density of states (DOS) for LSMO3-σ materials. Oxygen vacancy defects caused a shift of the total density of states (TDOS) features toward low binding energies and LSMO3-σ keep half-metal properties as well as LSMO3 ideal structure. In addition, the hybridization between the Mn-eg and O-2p orbital was weakened and the partial density of states (PDOS) of Mn indicated a strong d-d orbital interaction. By the result of oxygen vacancy formation energy, oxygen vacancy defects can be more easily formed in La-O layers (z = 0 and c/6) to compare with other layers (z = c/8, c/4 and c/2). The calculation result of optical properties suggested that the ideal LSMO could be produced strong absorption in the range of ultraviolet and visible light, while the LSMO3-σ with oxygen vacancies defects were presented weak absorption in the range of visible light.

Organization process of the hierarchical structures in microbially synthesized polyhydroxyalkanoates

Jun Xu,Bao-Hua Guo,Qiong Wu,Jin-Chun Chen,Guo-Qiang Chen,Jian-Jun Zhou,Yong Jiang,Lin Li 한국물리학회 2007 Current Applied Physics Vol.7 No.s1

cess of the high-order structures in biomaterials. Real-time Fourier transform infrared spectroscopy and optical microscopy demon-strated that helical segments formed along with the spherulite growth. Atomic force microscopy revealed the details of growth,twisting and branching of lamellar crystals. Cooperative packing of these twisting lamellae led to regular banded spherulites observedunder polarized light microscopy. Real-time observation on the crystallization process provided richer information than the characterization of the final structures; consequently, it provides deeper insight into the organization mechanism of the hierarchical structures.