24 research outputs found
Synthesis and Catalytic Activity of Surfactant-Templated Nanoporous TiO(2)
Nanoporous TiO(2) were synthesized via hydrolysis of titanium tetraisopropoxide (TTIP) in HCl acidic conditions using sodium dodecylsulfate (SDS) as a templating agent. The order of the nanostructure of samples before calcination was improved with increasing the SDS/TTIP molar ratio. The calcined samples presented uniform mesopore structure with the average diameter of 4-5 nm and considerably large surface areas over 200m(2)/g, although the periodicity of the nanostructure was exceedingly reduced by the removal of the template. The prepared TiO(2)
exhibited exceedingly higher activities on the catalytic oxidation of benzene compared to the commercial TiO(2), probably due to the difference of their pore suructures
Stability and Ly emission of Cold Stream in the Circumgalactic Medium: impact of magnetic fields and thermal conduction
Cold streams of gas with temperatures around play a crucial
role in the gas accretion on to high-redshift galaxies. The current resolution
of cosmological simulations is insufficient to fully capture the stability and
Ly emission characteristics of cold stream accretion, underscoring the
imperative need for conducting idealized high-resolution simulations. We
investigate the impact of magnetic fields at various angles and anisotropic
thermal conduction (TC) on the dynamics of radiatively cooling streams through
a comprehensive suite of two-dimensional high-resolution simulations. An
initially small magnetic field (), oriented
non-parallel to the stream, can grow significantly, providing stability against
Kelvin-Helmholtz instabilities and reducing the Ly emission by a factor
of compared to the hydrodynamics case. With TC, the stream evolution can
be categorised into three regimes: (1) the Diffusing Stream regime, where the
stream diffuses into the surrounding hot circumgalactic medium; (2) the
Intermediate regime, where TC diffuses the mixing layer, resulting in enhanced
stabilization and reduced emissions; (3) the Condensing Stream regime, where
the impact of magnetic field and TC on the stream's emission and evolution
becomes negligible. Extrapolating our findings to the cosmological context
suggests that cold streams with a radius of may fuel
galaxies with cold, metal-enriched, magnetized gas () for a longer time, leading to a broad range of Ly luminosity
signatures of .Comment: 19 pages, 15 figures, 1 video link (https://youtu.be/zhNCGoiUYgE), 3
Appendices; accepted to MNRAS (December 2023
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京都大学0048新制・課程博士博士(工学)甲第9178号工博第2094号新制||工||1220(附属図書館)UT51-2001-N224京都大学大学院工学研究科化学工学専攻(主査)教授 谷垣 昌敬, 教授 東谷 公, 教授 田門 肇学位規則第4条第1項該当Doctor of EngineeringKyoto UniversityDA