Graphene/M_xWO₃ (M=Na, K) nanohybrids with excellent electrical properties

Liu, B.,Yin, S.,Wu, X.,Wang, Y.,Huang, Y.,Wu, J.,Sekino, T.,Matsushita, J.,Lee, S.W.,Kobayashi, M.,Kakihana, M.,Sato, T. Pergamon Press ; Elsevier Science Ltd 2015 Carbon Vol.94 No.-

Graphene/M<SUB>x</SUB>WO<SUB>3</SUB> (M=Na, K) nanocomposites with different weight ratios were successfully synthesized using MBH<SUB>4</SUB> as a reducing agent in aqueous solution, followed by crystallization of amorphous precursors under calcination in H<SUB>2</SUB> (5vol.%)/N<SUB>2</SUB> atmosphere at 600<SUP>o</SUP>C. The coupled samples showed good shielding properties in NIR wavelength range together with certain visible lights transparency. The as-prepared tungsten bronze nanoparticles are homogeneously anchored on graphene sheets, and the graphene/tungsten bronze nanocomposite showed an enhanced electrical conductivity with good shielding properties in the NIR range together with certain visible lights transparency. With the increment of graphene amount in the composites, the contact between the graphene sheets was enhanced, and the M<SUB>x</SUB>WO<SUB>3</SUB> might enhance the charge transport properties of graphene by generating the short conductive path for electrons over the remained oxygenated functional groups. The synergistic effects could be observed in the composites. When 5wt.% or more graphene were composed into M<SUB>x</SUB>WO<SUB>3</SUB>, the hybrid composite showed the higher electrical conductivity than those of uncoupled graphene and tungsten bronze alone.

EFFECTS OF ALTITUDE ON COMBUSTION CHARACTERISTIC DURING COLD START OF HEAVY-DUTY DIESEL ENGINE

Z. C. KAN,D. M. LOU,Z. Z. CAO,Z. Y. HU,S. LIU,Z. H. YANG 한국자동차공학회 2017 International journal of automotive technology Vol.18 No.2

Altitude has a significant effect on combustion of heavy-duty diesel engines, especially during cold start. An experimental study on a heavy-duty diesel engine operating at different altitudes was conducted. Tests were based on a direct injection (DI) turbocharged diesel engine with intake and exhaust pressure controlled by the plateau simulation test system to stimulate altitude conditions including 0 m, 1000 m, 2000 m, 3000 m and 4000 m. Results indicated that the compression and expansion resistance moment reduced and the speed increased during the cranking period. The peak pressure of several cycles was increased during the start-up period; however, the expansion pressure dropped more and the indicated mean effective pressure (IMEP) reduced as the altitude rose. While at an altitude of over 2000 m, the peak pressure fluctuated obviously during the start-up period. The higher the altitude was, the more the fluctuation amplitude and cycle number increased and combustion instability enhanced, which resulted the start-up period time increasing at high altitude. When the altitude rose, the cycle-to-cycle variation of the peak pressure and speed fluctuation increased during the idle, the ignition and CA50 were delayed and the combustion duration was shortened. The effect of altitude on combustion characteristics of the diesel engine was more significant during the start-up period than during its idle period.

Planck Cold Clumps in the <i>λ</i> Orionis Complex. II. Environmental Effects on Core Formation

Yi, Hee-Weon,Lee, Jeong-Eun,Liu, Tie,Kim, Kee-Tae,Choi, Minho,Eden, David,II, Neal J. Evans,Francesco, James Di,Fuller, Gary,Hirano, N.,Juvela, Mika,Kang, Sung-ju,Kim, Gwanjeong,M. Koch, Patrick,Lee, American Astronomical Society 2018 The Astrophysical journal, Supplement series Vol.236 No.2

<P>Based on the 850 mu m dust continuum data from SCUBA-2 at James Clerk Maxwell Telescope (JCMT), we compare overall properties of Planck Galactic Cold Clumps (PGCCs) in the lambda Orionis cloud to those of PGCCs in the Orion A and B clouds. The Orion A and B clouds are well-known active star-forming regions, while the A Orionis cloud has a different environment as a consequence of the interaction with a prominent OB association and a giant H-II region. PGCCs in the lambda Orionis cloud have higher dust temperatures (T-d = 16.13 +/- 0.15 K) and lower values of dust emissivity spectral index (beta = 1.65 +/- 0.02) than PGCCs in the Orion A (T-d = 13.79 +/- 0.21 K, beta = 2.07 +/- 0.03) and Orion B (T-d = 13.82 +/- 0.19 K, beta =1.96 +/- 0.02) clouds. We find 119 substructures within the 40 detected PGCCs and identify them as cores. Out of a total of 119 cores, 15 cores are discovered in the lambda Orionis cloud, while 74 and 30 cores are found in the Orion A and B clouds, respectively. The cores in the lambda Orionis cloud show much lower mean values of size R = 0.08 pc, column density N(H-2) (9.5 +/- 1.2) x 10(22)cm(-2) , number density n(H-2) - (2.9 +/- 0.4) x 10 5 CM -3 , and mass M-core = 1.0 +/- 0.3 M(circle dot)compared to the cores in the Orion A [R = 0.11 pc, N(H-2) = (2.3 +/- 0.3) x 10(23) cm(-2), n(H-2) = (3.8 +/- 0.5) x 10(5)cm(-3) , and M-core = 2.4 +/- 0.3 M-circle dot] and Orion B [R = 0.16 pc, N(H-2) (3.8 +/- 0.4) x 10(23) cm(-2), n(H-2) = (15.6 +/- 1.8) x 10(5) cm(-3) , and M-core = 2.7 +/- 0.3 M-circle dot] clouds. These core properties in the A Orionis cloud can be attributed to the photodissociation and external heating by the nearby H rr region, which may prevent the PGCCs from forming gravitationally bound structures and eventually disperse them. These results support the idea of negative stellar feedback on core formation.</P>

An experimental and numerical study on the crush responses and energy absorption characteristics of single- and bi-layer cups under low-velocity impact

M.A. Ghasemabadian,M. Kadkhodayan,W. Altenhof,Y. Liu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.39 No.6

Observations on the crush responses and the energy absorption characteristics of single- and bi-layer deep-drawn cups subjected to experimental axial impact loading are presented in this manuscript. Bi-layer plates composed of aluminum and stainless steel alloys were fabricated by joining with adhesive and formed by a deep drawing process to produce the final cup shape. Impact testing was performed using a custom-built drop-tower system with a mass of 45.45 kg and impact velocities ranging from 2.8 m/s to 4.5 m/s. Various material and geometric parameters for the bi- and single-layer cups were considered in the study. Numerical simulations were conducted to investigate the deformation mechanisms and crushing behavior of the combined shells. Furthermore, based on the polynomial response surface method and using non-domain sorting genetic algorithm II, some multi-objective optimizations were performed on specific energy absorption, stroke efficiency, specific total efficiency, and initial peak load. Experimental and numerical results illustrated that the deformation of the bi-layer cups was different from the single-layer cups, especially in the head zone. Moreover, the specific total efficiency for specimens having a diameter of 55 mm and 65 mm were approximately 35% and 55% less than cups with a diameter of 45mm, respectively. It was found that the layer order of the bi-layer cup influences the energy absorption capacities of the specimen. Specifically, cups with steel as the outer layer experienced crush force efficiency and total efficiency of 6% and 5% higher than those with an aluminum outer layer, respectively.

Variation of magnetic properties with different annealed temperatures in the Ni_3[Fe(CN)_6]_2ㆍXH_2O

M. Liu,X.F. Bian,Y.F. Xia,Z. Bao,H.S. Wu,M.X. Xu 한국물리학회 2011 Current Applied Physics Vol.11 No.3

Molecular magnet nickel(II) hexacyanoferrate(III) powder Ni_3[Fe(CN)_6]_2ㆍXH_2O was prepared by coprecipitation method. The coprecipitated powder was annealed in vacuum at different temperatures of 140,and 160 ℃. Water molecules contained in Prussian blue analogues were removed by heating. The annealing of Ni^II ferricyanide induced an inner charge transfer from Ni^II towards Fe^III to form the mixed valence system Ni(II) Ni(III) ferri-ferro-cyanide. Variation of magnetic properties with different annealed temperatures was studied by elemental analysis, powder X-ray diffraction, transmission electron microscopy, Fourier transform infrared, and Mössbauer and magnetization measurements. The differences in magnetic phase transition temperature, coercivity, remanence and effective magnetization are studied. Differences in magnetic properties may be attributed to a partial charge transfer from Ni^II to Fe^III.

Highly flexible, erosion resistant and nitrogen doped hollow SiC fibrous mats for high temperature thermal insulators

Liu, Y.,Liu, Y.,Choi, W.,Chae, S.,Lee, J.,Kim, B. S.,Park, M.,Kim, H. Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.6

<P>Thermally stable and chemical resistant silicon carbide (SiC) fibrous mats have drawn much attention as a high-temperature thermal insulator in top end equipment and technology. Herein, novel free-standing, flexible, acid/alkali-resistant and nitrogen doped (N-doped) hollow SiC fibrous mats bearing ultralow thermal conductivity are reported. The materials were fabricated via a three-step process: the preparation of core-shell fibers from polymeric precursors by co-axial electrospinning, the thermal or electron beam irradiation curing process and pyrolysis process. The as-obtained continuous fibers manifested an oval-shape hollow structure and the thickness of the cavity wall was approximately 1.5 mu m. The crystal pattern was obtained after pyrolysis over 1300 degrees C under a nitrogen atmosphere. The morphology, composition, curing and formation mechanisms of N-containing hollow SiC fibers with texture and porous surfaces were elaborately analysed. These facilely fabricated N-doped hollow SiC fibrous mats possess good flexibility, noninflammability, high thermal stability, erosion resistance, light weight (0.218 g cm(-3)) and low thermal conductivity at high temperature (0.039 W m(-1) K-1), suggesting promising application as a high temperature thermal insulator.</P>

Fuel Cell Based on Novel Hyper-Branched Polybenzimidazole Membrane

Changzhi Liu,Sher Bahadar Khan,이민주,김광인,Kalsoom Akhtar,한학수,Abdullah M. Asiri 한국고분자학회 2013 Macromolecular Research Vol.21 No.1

A novel hyper-branched polybenzimidazole (HB-PBI) has been synthesized and efficiently utilized as a conducting polymer for the fabrication of an efficient high temperature fuel cell. The developed fuel cell showed outstanding proton conductivity (0.168 Scm-1 at 150 ºC) along with excellent single cell performance, displaying a maximum power density of 0.346 Wcm-2. The HB-PBI has been synthesized by polymerization of bibenzimidazole diterephthalic acid (BBIDTA) and 3,3'-diaminobenzene in the presence of poly phosphoric acid while the BBIDTA was synthesized by treating trimellitic anhydride with 3,3'-diaminobenzene. Both HB-PBI and BBIDTA were structurally characterized by nuclear magnetic resonance (1H and 13C NMR). HB-PBI showed high thermal stability and mechanical properties, findings that were corroborated by thermogravimetric analysis and use of a universal testing machine. Additionally, proton conduction and the thermal and mechanical properties of HB-PBI were compared with polybenzene imidazole (m-PBI), and found that HB-PBI has higher proton conducting, thermal and mechanical properties.

Characterization of trnk-matk Gene in Potato Plastid

Jung, M 한국식물조직배양학회 1998 식물생명공학회지 Vol.25 No.6

Interfacial fabrication and property of hydroxyapatite/polylactideresorbable bone fixation composites

S.M. Zhang,J. Liu,W. Zhou,L. Cheng,X.D. Guo 한국물리학회 2005 Current Applied Physics Vol.5 No.5

Based on surface modication of hydroxyapatite with silane derivatives, interfacial fabrications of hydroxyapatite (HAP)/poly-lactide (PLA) resorbable bone xation composites are realized. The results indicate that interfacial adhesion, swelling property, andultimate mechanical properties of the HAP/PLA composites are signicantly improved. As a result, the maximum bending strengthenhances 27.8%. Scanning electron microscopy (SEM) observation suggests that the modied HA particles are homogeneously dis-persed in the composites, their size ranges are about 215l m. The modied HA/PLA composites are of toughened rupture. Thisconclusion is consistent with bending property of the composites. Finally, a possible mechanism for the interfacial adhesion is alsodiscussed..

Edge-directed [(M₂)₂L₄] tetragonal metal–organic polyhedra decorated using a square paddle-wheel secondary building unit

Jaya Prakash, M.,Oh, Minhak,Liu, Xinfang,Han, Kwi Nam,Seong, Gi Hun,Lah, Myoung Soo Royal Society of Chemistry 2010 Chemical communications Vol.46 No.12

<P>A general strategy was developed for edge-directed self-assembly of tetragonal metal–organic polyhedra (MOPs) having a <I>C</I><SUB>4</SUB> symmetry Cu<SUP>II</SUP><SUB>2</SUB>(COO)<SUB>4</SUB> paddle-wheel as a secondary building unit, using <I>C</I><SUB>2</SUB> symmetric dicarboxylic ligands as pincer-type primary building units.</P> <P>Graphic Abstract</P><P>Augmented tetragonal metal–organic polyhedra (MOPs) were self-assembled from <I>C</I><SUB>2</SUB> symmetric bidentate ligands based on a Cu(<SMALL>II</SMALL>) paddle-wheel moiety as a secondary building unit, where the ligands occupy the edges of the tetragonal cages. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b925335a'> </P>