Characteristics of the high-power reconnection heating were measured for the first time directly by two-dimensional measurements of ion and electron temperatures. While electrons are heated mainly inside the current sheet by the Ohmic heating power, ions are heated mainly by fast shock or viscosity damping of the reconnection outflow in the two downstream areas. The magnetic reconnection converts the energy of reconnecting magnetic field B(p) mostly to the ion thermal energy, indicating that the reconnection heating energy is proportional to B(p)(2).
The self-association of octan-1-01 in the pure liquid state and in decane solutions has been studied by nearinfrared spectroscopic observation over the temperature range 298.1-348.1 K and also by viscosity, self-diff usion and NMR measurements. The absorption bands assigned to the hydroxy group are superimposed on several bands attributed to the methylene groups belonging to both the alcohol and decane molecules. A superior technique using a computer was adopted for the cancellation of the absorption bands due to the methylene groups so as to obtain the net OH absorption bands. The analysis of the sharp band at 1410 nm (the first overtone band of the OH-stretching vibration attributed to the free OH-monomer and partly to the OH-polymer) leads to the conclusion that the mean degree of association n (i.e. the average size of the multimer in monomeric units) in the polymer of octan-1-01 is ca. four, both in the liquid and in decane solutions under the temperature conditions given above. From the arguments about the aggregated species, a cyclic tetramer was proposed as the associated alcohol species in the liquid and in decane solutions. The association equilibrium constant and other thermodynamic properties such as changes in enthalpy, entropy and Gibbs energy for tetramer formation were also determined.
The dissociation of dimers of cis-9-octadecenoic acid into its monomeric species in its pure liquid was studied by near-infrared spectroscopic measurements over a temperature range of 8.6-84.4 OC. An absorption band at 1445 nm, which is attributed to the free OH of the fatty acid molecules, appeared even at relatively low temperatures; its peak height increased with increasing temperature. This shows that the dissociation of the acid dimers occurs even at low temperatures and increases with increasing temperature. The molar absorption coefficient at 1445 nm for the monomeric OH stretch mode in the carboxyl group was obtained through the absorbance measurements in carbon tetrachloride solution at very low concentrations. The molar absorption coefficient and the absorbance for the neat sample at various temperatures, T, give the temperature dependence of the degree of dissociation, a, for dimeric cis-9-octadecenoic acid into monomers in the liquid state. The a-T curve has two break points at 30 and 55 OC. The break-point temperatures correspond to the transition temperatures in the liquid structures of cis-9-octadecenoic acid: 30 OC corresponds to a quasi-smectic liquid crystal to a more disordered liquid crystal, and 55 OC corresponds the disordered liquid crystal to isotropic liquid.' Namely, the transitions in the liquid state of cis-9-octadecenoic acid are attributable to the presence of the monomeric molecules produced by the dissociation of the dimeric acid: The monomeric molecules existing as an impurity would initiate the transition in the pure liquid state consisting mainly of cis-9-octadecenoic acid dimers.
To
enhance the hydrogenation activity of alumina supported Au (Au/Al2O3) catalyst for selective hydrogenation of 5-hydroxymethylfurfural
(HMF), an important biomass-derived aldehyde, Al2O3 support was modified with iron oxide (FeO
x
). The apparent catalytic activity of the FeO
x
/Al2O3 supported Au (Au/FeO
x
/Al2O3) catalysts increased
as an increase of Fe loading up to 10 wt % (3–4 times higher
than Au/Al2O3). When the Fe loading was more
than 10 wt %, the apparent catalytic activity decreased, and Au/α-Fe2O3 showed much lower activity than Au/Al2O3. The Fe K-edge X-ray absorption fine structure (XAFS)
spectra and the atomic scale observation using aberration corrected
scanning transmission electron microscopy (Cs-STEM) suggested positive
and negative effects of FeO
x
support.
As the positive effect, FeO
x
promotes
formation of Au clusters by reduction of Au single atoms having low
or no catalytic activity for the hydrogenation. On the other hand,
as the negative effect, FeO
x
, more specifically,
large α-Fe2O3, can form buried structure
of Au clusters in FeO
x
due to reduction
of α-Fe2O3 to Fe metal by H2 pretreatment. The buried structure of Au clusters is responsible
for the decrease of hydrogenation activity at high Fe loading. In
contrast, dispersed Fe2O3 species of Au/FeO
x
/Al2O3 with less than
20 wt % of Fe loading was not subjected to the reduction of Fe2O3 species to Fe metal, and the Au clusters were
exposed on the support surface. Therefore, the dispersed Fe2O3 on Al2O3 is effective to enhance
the activity of Au catalysts for the hydrogenation because of the
formation of exposed small Au clusters.
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