7,883 research outputs found
Studies on the oxidation of hexamethylbenzene 2: Preparation of dimethylpyromellitic acid
Hexamethylbenzene (HMB) was difficult to be oxidized with an alkaline potassium permanganate solution, since HMB was insoluble in an aqueous alkaline solution. But, when HMB was warmed with 50% nitric acid for a short time, and then treated with aqueous potassium permanganate, the reaction occurred readily and dimethylpyromellitic acid was obtained. When HMB was warmed with 50% nitric acid for 1 to 2 minutes, a yellow material was produced, which was soluble in hot aqueous potassium hydroxide, though free from carboxylic acids. It contained a little amount of bis-(nitromethyl)prehnitene and several unknown compounds. Further, the heat stability of polyimide prepared by the reaction of tetramethyldimethylpyromellitate with 4,4 prime-diaminodiphenylmethane turned out to be nearly equal to that of polyimide prepared from tetramethylpyromellitate
Instanton and Monopole in External Chromomagnetic Fields
We study properties of instanton and monopole in an external chromomagnetic
field. Generally, the 't Hooft ansatz is no longer a solution of the Yang-Mills
field equation in the presence of external fields. Therefore, we investigate a
stabilized instanton solution with minimal total Yang-Mills action in a
nontrivial topological sector. With this aim, we consider numerical
minimization of the action with respect to the global color orientation, the
anisotropic scale transformation and the local gauge-like transformation
starting from a simple superposed gauge field of the 't Hooft ansatz and the
external color field. Here, the external color field is, for simplicity, chosen
to be a constant Abelian magnetic field along a certain direction. Then, the
4-dimensional rotational symmetry O(4) of the instanton solution is reduced to
two 2-dimensional rotational symmetries due to the effect of
a homogeneous external field. In the space \mib{R}^{3} at fixed , we find
a quadrupole deformation of this instanton solution. In the presence of a
magnetic field , a prolate deformation occurs along the direction of
. Contrastingly, in the presence of an electric field an
oblate deformation occurs along the direction of . We further discuss
the local correlation between the instanton and the monopole in the external
field in the maximally Abelian gauge. The external field affects the appearance
of the monopole trajectory around the instanton. In fact, a monopole and
anti-monopole pair appears around the instanton center, and this monopole loop
seems to partially screen the external field.Comment: 15 pages,8 figure
New Approach for Evaluating Incomplete and Complete Fusion Cross Sections with Continuum-Discretized Coupled-Channels Method
We propose a new method for evaluating incomplete and complete fusion cross
sections separately using the Continuum-Discretized Coupled-Channels method.
This method is applied to analysis of the deuteron induced reaction on a 7Li
target up to 50 MeV of the deuteron incident energy. Effects of deuteron
breakup on this reaction are explicitly taken into account. Results of the
method are compared with those of the Glauber model, and the difference between
the two is discussed. It is found that the energy dependence of the incomplete
fusion cross sections obtained by the present calculation is almost the same as
that obtained by the Glauber model, while for the complete fusion cross
section, the two models give markedly different energy dependence. We show also
that a prescription for evaluating incomplete fusion cross sections proposed in
a previous study gives much smaller result than an experimental value.Comment: 10 pages, 5 figure
Properties of hadron and quark matter studied with a molecular dynamics
We study the hadron-quark phase transition in a molecular dynamics (MD) of
quark degrees of freedom. The hadron state at low density and temperature, and
the deconfined quark state at high density and temperature are observed in our
model. We investigate the equations of state and draw the phase-diagram at wide
baryon density and temperature range. We also discuss the transport property,
e.g. viscosity, of matter. It is found that the ratio of the shear
viscosity to the entropy density is less than one for quark matter.Comment: Poster presentation at Quark Matter 200
Studies on the oxidation of hexamethylbenzene 1: Oxidation of hexamethylbenzene with nitric acid
The oxidative reaction of hexamethylbenzene (HMB) with nitric acid was studied, and the hitherto unknown polymethylbenzenepolycarboxylic acids were isolated: tetramethylphthalic anhydride, tetramethylisophthalic acid, 1,3,5-, 1,2,4- and 1,2,3-trimethylbenzenetricarboxylic acids. When HMB was warmed with 50% nitric acid at about 80 C, tetramethylphthalic anhydride and tetramethylisophthalic acid were initially produced. The continued reaction led to the production of trimethylbenzenetricarboxylic acids, but only slight amounts of dimethylbenzenetetracarboxylic acids were detected in the reaction mixture. Whereas tetramethylphthalic anydride and tetramethylisophthalic acid were obtained, pentamethylbenzoic acid, a possible precursor of them, was scarcely produced. On the other hand, a yellow material extracted with ether from the initial reaction mixture contained bis-(nitromethyl)prehnitene (CH3)4C6(CH2NO2)2, which was easily converted into the phthalic anhydride
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