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 Lyα\alpha emission of Cold Stream in the Circumgalactic Medium: impact of magnetic fields and thermal conduction

Cold streams of gas with temperatures around $10^4 \, \rm K$ 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$\alpha$ 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 ($\sim 10^{-3} \, \rm \mu G$), oriented non-parallel to the stream, can grow significantly, providing stability against Kelvin-Helmholtz instabilities and reducing the Ly$\alpha$ emission by a factor of $<20$ 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 $\leq 1 \rm \, \rm kpc$ may fuel galaxies with cold, metal-enriched, magnetized gas ($B \sim 0.1-1 \, \rm \mu G$) for a longer time, leading to a broad range of Ly$\alpha$ luminosity signatures of $\sim 10^{37}-10^{41}\, \rm \, erg \, s^{-1}$.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