Molecular Reaction Dynamics in Gases, Liquids and Interfaces: General Discussion

It is usually asserted that H2O is characterized by an sp3 distorted hybridization with the two lone pairs degenerate. Actually, this is the case of water in liquid or solid state. In the gas phase, when the molecule is isolated, the two O\u2013H bonding orbitals form an angle of about 104.5 and the two lone pairs are not degenerate, being one aligned along the C2v molecular axis (3a1, the sp2 lone pair orbital) and the other one perpendicular to the molecular plane (1b1, the 2pip oxygen non bonding orbital). This is well con\ufb01rmed by recent measurements from my laboratory in a Penning ionization electron spectroscopy study of water molecules by neon metastable atoms. In our experiment, due to the available energy of Ne*(3P2,0) atoms, the two not degenerate lone pair orbitals of the H2O molecule are selectively involved in the ionization process. The non-degeneracy of the two lone pairs is also well con\ufb01rmed by the presence of two separated bands in the electron energy spectra of H2O, obtained by photo- or Penning ionization, assigned to the two different approach directions of the Ne* atom to the molecule (both towards the O atom: one along the C2v molecular axis and the other one along the perpendicular direction of the molecular plane)

Effect of sibutramine on cardiovascular outcomes in overweight and obese subjects.

BACKGROUND: The long-term effects of sibutramine treatment on the rates of cardiovascular events and cardiovascular death among subjects at high cardiovascular risk have not been established. METHODS: We enrolled in our study 10,744 overweight or obese subjects, 55 years of age or older, with preexisting cardiovascular disease, type 2 diabetes mellitus, or both to assess the cardiovascular consequences of weight management with and without sibutramine in subjects at high risk for cardiovascular events. All the subjects received sibutramine in addition to participating in a weight-management program during a 6-week, single-blind, lead-in period, after which 9804 subjects underwent random assignment in a double-blind fashion to sibutramine (4906 subjects) or placebo (4898 subjects). The primary end point was the time from randomization to the first occurrence of a primary outcome event (nonfatal myocardial infarction, nonfatal stroke, resuscitation after cardiac arrest, or cardiovascular death). RESULTS: The mean duration of treatment was 3.4 years. The mean weight loss during the lead-in period was 2.6 kg; after randomization, the subjects in the sibutramine group achieved and maintained further weight reduction (mean, 1.7 kg). The mean blood pressure decreased in both groups, with greater reductions in the placebo group than in the sibutramine group (mean difference, 1.2/1.4 mm Hg). The risk of a primary outcome event was 11.4% in the sibutramine group as compared with 10.0% in the placebo group (hazard ratio, 1.16; 95% confidence interval [CI], 1.03 to 1.31; P=0.02). The rates of nonfatal myocardial infarction and nonfatal stroke were 4.1% and 2.6% in the sibutramine group and 3.2% and 1.9% in the placebo group, respectively (hazard ratio for nonfatal myocardial infarction, 1.28; 95% CI, 1.04 to 1.57; P=0.02; hazard ratio for nonfatal stroke, 1.36; 95% CI, 1.04 to 1.77; P=0.03). The rates of cardiovascular death and death from any cause were not increased. CONCLUSIONS: Subjects with preexisting cardiovascular conditions who were receiving long-term sibutramine treatment had an increased risk of nonfatal myocardial infarction and nonfatal stroke but not of cardiovascular death or death from any cause. (Funded by Abbott; ClinicalTrials.gov number, NCT00234832.