Photochemistry of the water dimer: time-dependent quantum wave-packet description of the dynamics at the S1-S0 conical intersection.

The photoinduced electron-driven proton-transfer dynamics of the water-dimer system has been investigated by time-dependent quantum wave-packet calculations. The main nuclear degrees of freedom driving the system from the Frank-Condon region to the S(0)-S(1) conical intersection are the distance between the oxygen atoms and the displacement of the hydrogen atom from the oxygen-oxygen bond center. Two important coupling modes have been investigated: Rotation of the H-donating water dangling proton and asymmetric stretching of the H-accepting water dangling protons' O(a)H bonds.

A computational study on the mechanism of intramolecular oxo-hydroxy phototautomerism driven by repulsive pi sigma* state.

Potential energy (PE) surfaces of the lowest excited states of the 4(3H)-pyrimidinone/4-hydroxypyrimidine system were investigated with the aid of the CC2 and CASSCF methods of the electronic structure theory. These studies resulted in identification of a low-lying pi sigma* state, which is dissociative with respect to the stretching of the N-H or O-H bonds in the oxo and hydroxy structures of the compound, respectively. After initial excitation to the lowest local n pi* and/or pi pi* singlet states, the system can access the PE surface of the pi sigma* state by crossing a low barrier.

[Diagnostic difficulties in a case of multifocal changes in the brain in computerized tomography and in magnetic resonance imaging].

This paper presents a case of multifocal metastases in the brain, which on the basis of typical imaging magnetic resonance and computerized tomography suggested possible parasitic changes (cerebral cysticercosis). On the basis of these pictures cerebral cysticercosis was diagnosed, in spite in the absence of serologic changes in blood and cerebrospinal fluid. The lack of improvement after anticysticercosis drugs, the further course of the disease as well as new foci located in other organs outside the brain, allowed to recognize numerous metastases in the brain although until the end of the clinical observation the primary lesion of the neoplasm was not found.