No abstract

Internal rotation of methyl group in o and mtoluidine cations as studied by pulsed field ionization-zero kinetic energy spectroscopy

Objective-To obtain normal values for intracardiac pressures in the human fetus. Design-Intracardiac pressures were measured directly in the four chambers of the human fetal heart during clinically indicated invasive obstetric procedures. Setting-Department of fetal medicine in a tertiary referral centre. Patients-39 fetuses between 16 and 29 weeks of gestation. Results-The ventricular waveforms obtained were similar to those found in postnatal life. There was an increase in ventricular systolic and end diastolic pressures with advancing gestation. There was no diVerence between left and right ventricular pressures. Atrial pressures were equal and remained constant in the gestational age range studied. Conclusions-Fetal cardiovascular pressure measurements in the normal fetus assist in understanding the fetal circulation, and provide a basis for the assessment of cases of congenital heart disease that may be amenable to intrauterine treatment.

Quantum yields and rates of intersystem crossing and internal conversion are obtained for the lowest excited singlet state of collisionless phenol. It is found that internal conversion is the dominant decay channel, even at the origin of S1, in contrast to previously studied molecules. Also, triplet lifetimes measured as a function of vibrational energy are an order of magnitude shorter than in other isoelectronic aromatics. Hydrogen bonding by water and in a dimer is found to lengthen the singlet lifetime and decrease the quantum yield of internal conversion. This behavior parallels the effects, in solution, of going from a nonpolar to a polar solvent, indicating that substantial solvation effects are caused by a single hydrogen bond.