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Influence of Sub-zero Temperatures on the Dynamic Behaviour of Foam Concrete with Sand
Yongliang He,Mingshi Gao,Dong Xu,Xin Yu 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.10
The mechanical properties of foam concrete with sand at different low temperatures and different strain rates were studied. Foam concrete with sand at low temperatures (-10, -20, and -30oC) were tested using a split Hopkinson pressure bar (SHPB) apparatus with different impact pressures (0.15, 0.20, 0.25, 0.30, and 0.35 MPa). The experimental results show that the porosity of sand containing foam concrete with a density of 1,000, 1,200, 1,400 kg/m3decreases with increasing density. In the same strain rate range, the lower the temperature of the same density foam concrete with sand, the greater the ultimate compressive strength. The change in strength was caused by the presence of pore water or ice in the foam concrete with sand in low-temperature conditions. The dynamic compressive strength of foam concrete with sand decreases with increasing strain rate. The macroscopic failure of foam concrete was closely related to the energy absorption and dependent on the rate. The total dissipated energy of the low-temperature foam concrete with sand increased linearly as the temperature decreased. The research results provide the low-temperature mechanical properties of foam concrete with sand, which provides a reference for the application of foam concrete with sand.
Kim, Jin Yeong,Jin, Mingshi,Lee, Kyung Joo,Cheon, Jae Yeong,Joo, Sang Hoon,Kim, Ji Man,Moon, Hoi Ri Springer 2012 NANOSCALE RESEARCH LETTERS Vol.7 No.1
<P>The preparation of redox-active metal-organic framework (<I>ra</I>-MOF)-supported Pd nanoparticles (NPs) via the redox couple-driven method is reported, which can yield unprotected metallic NPs at room temperature within 10 min without the use of reducing agents. The Pd@<I>ra</I>-MOF has been exploited as a precursor of an active catalyst for CO oxidation. Under the CO oxidation reaction condition, Pd@<I>ra</I>-MOF is transformed into a PdO<SUB><I>x</I></SUB>-NiO<SUB><I>y</I></SUB>/C nanocomposite to generate catalytically active species <I>in situ</I>, and the resultant nanocatalyst shows sustainable activity through synergistic stabilization.</P>
Catalytic properties of highly ordered crystalline nanoporous tungsten oxide in butanol dehydration.
Choi, Hyeonhee,Lee, Eunok,Jin, Mingshi,Park, Young-Kwon,Kim, Ji Man,Jeon, Jong-Ki American Scientific Publishers 2014 Journal of nanoscience and nanotechnology Vol.14 No.11
<P>Highly ordered mesoporous tungsten oxide (meso-WO3) was successfully synthesized using mesoporous silica KIT-6 as a hard template via the nanoreplication method. The physicochemical properties of meso-WO3 were characterized by X-ray diffraction, nitrogen adsorption-desorption, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption of ammonia, and infra-red spectroscopy of adsorbed pyridine. No oxidation state other than WO3 was observed in the meso-WO3 sample. Lewis acid sites were dominant in meso-WO3, which could be confirmed by infra-red spectroscopy of pyridine and temperature-programmed desorption of ammonia. Its catalytic behavior in 2-butanol dehydration was investigated in a fixed bed reactor and compared with that of the WO3/MCM-41 catalyst prepared by the atomic layer deposition method. The meso-WO3 catalyst exhibited higher 2-butanol dehydration activity than that of the WO3/MCM-41 catalyst, which is ascribed to the stronger acidity as well as higher amount of acid sites that are mainly composed of Lewis acid sites in the meso-WO3 catalyst.</P>
Kang, Narae,Park, Ji Hoon,Jin, Mingshi,Park, Nojin,Lee, Sang Moon,Kim, Hae Jin,Kim, Ji Man,Son, Seung Uk American Chemical Society 2013 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.135 No.51
<P>Hollow microporous organic networks (<B>H-MON</B>s) were prepared by a template method using silica spheres. The shell thickness was delicately controlled by changing the synthetic conditions. The <B>H-MON</B>s were used as a template for the synthesis of nanoparticulate Co<SUB>3</SUB>O<SUB>4</SUB> hollows which showed excellent catalytic performance in H<SUB>2</SUB>O<SUB>2</SUB> oxidation.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2013/jacsat.2013.135.issue-51/ja411263h/production/images/medium/ja-2013-11263h_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja411263h'>ACS Electronic Supporting Info</A></P>
Park, Jung-Nam,Shon, Jeong Kuk,Jin, Mingshi,Hwang, Seong Hee,Park, Gwi Ok,Boo, Jin-Hyo,Han, Tae Hee,Kim, Ji Man The Chemical Society of Japan 2010 Chemistry letters Vol.39 No.5
<P>Highly ordered mesoporous α-Mn<SUB>2</SUB>O<SUB>3</SUB> with well-defined mesopores, high surface area, and high oxygen vacancy exhibits excellent catalytic activity toward H<SUB>2</SUB>O<SUB>2</SUB> decomposition at low temperature.</P>
Pretreatment Effect on CO Oxidation over Highly Ordered Mesoporous Silver Catalyst
Jeong Kuk Shon,Jung-Nam Park,Seong Hee Hwang,Mingshi Jin,Kiyoung Moon,부진효,한태희,김지만 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.2
Highly ordered mesoporous silver material was successfully synthesized from a mesoporous silica template (KIT-6) with 3-d channel structure using the nano-replication method. The effects of H2 or O2 pretreatments on the catalytic performance of the mesoporous silver were investigated using a temperature programmed CO oxidation technique in a fixed bed reactor. The mesoporous silver material that was pretreated with H2 exhibited an excellent catalytic activity compared to the as-prepared and O2-pretreated catalysts. Moreover, this present mesoporous silver material showed good catalytic stability. For the CO oxidation, the apparent activation energy of the H2-pretreated mesoporous silver catalyst was 61 ± 0.5 kJ mol‒1, which was also much lower than the as-prepared (132 ± 1.5 kJ mol‒1) and O2-pretreated (124 ± 1.4 kJ mol‒1) catalysts.
Li, Xiuhua,Wu, Xue,Kim, Ji Man,Kim, Sung Soo,Jin, Mingshi,Li, Donghao Springer-Verlag 2009 Journal of the American Society for Mass Spectrome Vol.20 No.11
<P>Mesoporous silica, SBA-15 was successfully functionalized with quinoline moiety, and was applied as a matrix in the MALDI-TOF-MS analysis of small molecules. The modified SBA-15 material [SBA-15-8-(3-(triethoxysilyl)propoxy) quinoline, SBA-15-8QSi] was obtained by using calcined SBA-15 and 8-hydroxy quinoline. The structure of the functionalized mesoporous material was systemically characterized by TEM, the N<SUB>2</SUB> adsorption-desorption isotherm technique and FT-IR spectra. Compared with DHB and SBA-15, SBA-15-8QSi demonstrated several advantages in the analysis of small molecules with MALDI-TOF-MS, such as less background interference ions, high homogeneity, and better reproducibility. Based on these results, the various analytical parameters were optimized. The ideal operating conditions were (1) methanol used as the dissolving solvent; (2) sample first dropping method; (3) a ratio between the analyte and the matrix of 3.5:10. Under these optimization conditions, a low detection limit (8 pmol for L-Arginine-HCl) and high reproducibility (≤29%) were obtained. This technique was successfully applied to the analysis of various types of small molecules, such as saccharides, amino acids, metabolites, and natural honey.</P>