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Neutron activation analysis and gamma-ray spectroscopy were used to determine the quantity of potassium and sodium in an ash sample of Tabebuiasp bombarded with thermal neutrons. These techniques, widely applied in nuclear physics, can be used in the context of wood science as an alternative for the usual physical chemistry methods applied in this area. The quantity of K and Na in an 8.60±0.10 mg of ash was determined as being 1.3±0.3 mg and 11.0±1.8 μg, respectively. The ratio of Tabebuiasp converted into ash was also determined as 0.758±0.004%.Neutron activation analysis and gamma-ray spectroscopy were used to determine the quantity of potassium and sodium in an ash sample of Tabebuiasp bombarded with thermal neutrons. These techniques, widely applied in nuclear physics, can be used in the context of wood science as an alternative for the usual physical chemistry methods applied in this area. The quantity of K and Na in an 8.60±0.10 mg of ash was determined as being 1.3±0.3 mg and 11.0±1.8 μg, respectively. The ratio of Tabebuiasp converted into ash was also determined as 0.758±0.004%.

In this paper, ν-principal cycles of surfaces immersed in ∝4are studied. In terms of geometric invariants, an integral expression for the first derivative of the Poincaré mapping associated with a ν-principal cycle is obtained.

The structure of single-particle levels in the second minima of ^237,239,241Pu was analyzed with the help of an axially-deformed Woods-Saxon potential. The nuclear shape was parametrized in terms of the cassinian ovaloids. A parametrization of the spin-orbit part of the potential was obtained in the region corresponding to large deformations (second minimum), depending only on the nuclear surface area. With this parametrization, we were able to reproduce successfully the spin, parity and energies of the rotational band built on the 8 s isomeric state in ²³⁹Pu and, also, a spin assignment for both isomeric states in ²³⁷Pu and ²⁴¹Pu was carried out.

Loewner's umbilic-index conjecture cannot be extended to surfaces immersed in ℝ4. More precisely, given n∈ ℤ, there exists an analytic surface immersed in ℝ4having an isolated umbilic point of index n/2.