Nucleophilic substitution with two reactive centers: The CN(-) + CH3I case.

The nucleophilic substitution reaction CN(-) + CH3I allows for two possible reactive approaches of the reactant ion onto the methyl halide, which lead to two different product isomers. Stationary point calculations predict a similar shape of the potential and a dominant collinear approach for both attacks. In addition, an H-bonded pre-reaction complex is identified as a possible intermediate structure. Submerged potential energy barriers hint at a statistical formation process of both CNCH3 and NCCH3 isomers at the experimental collision energies. Experimental angle- and energy differential cross sections show dominant direct rebound dynamics and high internal excitation of the neutral product. No distinct bimodal distributions can be extracted from the velocity images, which impedes the indication of a specific preference towards any of the product isomers. A forward scattering simulation based on the experimental parameters describes accurately the experimental outcome and shows how the possibility to discriminate between the two isomers is mainly hindered by the large product internal excitation.

Formation of cyanopolyyne anions in the interstellar medium: the possible role of permanent dipoles.

The possibility of attaching near-threshold electrons to N-terminated carbon chains, like those observed in the outer envelopes of carbon-rich stars, is examined via accurate quantum chemistry orbital structures evaluation and quantum scattering analysis of the corresponding extra-electron wavefunctions at meV energies. It is shown that the differences in the signs and sizes of the permanent dipole moments which exist for both the neutral and anionic species of the C(n)N series of molecules play a significant role in suggesting or excluding possible energy paths to permanent anion formations of cyanopolyynes, for which the cases with n from 1 to 7 are examined in more detail.

Electron scattering cross sections from anthracene over a broad energy range (0.00001-10,000 eV).

We report a computational investigation of electron scattering by anthracene (C14H10) in the gas phase. Integral and differential cross sections have been calculated by employing two distinct ab-initio quantum scattering methods: the symmetry adapted-single centre expansion method (ePOLYSCAT) and a screening corrected form of the independent atom model (IAM-SCAR) at low and high energies, respectively. After a detailed evaluation of the current results, we present a complete set of integral scattering cross sections from 0.00001 to 10,000 eV.

Electron scattering cross section calculations for polar molecules over a broad energy range.

We report computational integral and differential cross sections for electron scattering by two different polar molecules, HCN and pyrimidine, over a broad energy range. We employ, for low energies, either the single-centre expansion (ePOLYSCAT) or the R-matrix method, while for the higher energies we select a corrected form of the independent-atom representation (IAM-SCAR). We provide complete sets of integral electron scattering cross sections from low energies up to 10,000 eV. Our present calculated data agree well with prior experimental results.

Modeling chemical evolution in a cold molecular plasma: quantum dynamics of CF2(-) intermediates after electron attachment.

A dynamical study is presented for the chemical processes induced by electrons (with energies up to about 16 eV) on gaseous CF(2) (X(1)A(1) state), one of the important components of plasma etching molecular mixtures. The nuclear deformations from the C(2v) initial geometry are seen to lead to different anionic intermediates that suggest different chemical evolutions into final fragments. All nuclear motions are shown to be effective for the formation of a variety of resonances which could lead to different final fragments. The effect of the above vibrational activation of the transient anionic states initially formed at the equilibrium geometry is analyzed and discussed in detail, providing compelling evidence and physical reasons for the fragment observations given by various experiments on such plasmas.

Nautilus survey on chronic venous diseases.

AIM: The large diffusion of venous disease (CVD) has been confirmed by several epidemiological studies in Europe and the USA. Since general practitioners (GPs) are the first segment of the population to evaluate for CVD, the Italian Project Nautilus (concerning vascular prevention) organized a monitoring campaign in 2009 with the aim of studying CVD using the CEAP classification criteria. METHODS: More than 1000 GPs were included in the survey. The study produced anamnestic and clinical data on more than 10,000 patients with CVD divided into three age segments: 60 years. Of these results, 83% were considered valid for a statistical evaluation. RESULTS: The prevalent population in CVD includes adult and aging subjects; four out of five are women. The number of pregnancies is the first risk or predisposing factor in the adult population, and prolonged standing is the first cause in younger subjects. Excess weight and previous thromboses, either superficial (SVT) or deep (DVT), become more significant factors with advancing age and included, respectively, 58% and 44% of the study's subjects over the age of 60. The most severe signs of CVD (edema, venous ulcers) show a significant progression in the aging segment of the population. Edema is present in 50% of the aging population, and inflammatory endothelial activation (swollen, heavy or painful legs) also increases with aging. Symptoms related to hemorrheological activation (including itching, nocturnal cramps) progress in parallel with increasing signs. A history of previous SVT or DVT episodes is the determining factor in more severe signs (CEAP: C4-C6) in more than 50% of the studied patients in comparison with only 20% of patients without a history for SVT or DVT. Diabetes is associated with more severe signs in 50% of patients. CONCLUSION: The Nautilus Survey of CVD indicates determining factors associated with the beginning and progression of CVD in three different age segments. These factors may be considered as clinically significant parameters for defining the clinical evolution of CVD. The observations are useful to evaluate the best preventive and treatment options on the basis of the most recent pathophysiological considerations.

Controversy and consensus in the management of upper gastrointestinal disease in primary care. The International Gastro Primary Care Group.

Approximately 5% of all primary care consultations in the UK are for upper gastrointestinal (GI) diseases, the most common of which is dyspepsia, with a prevalence of between 25 and 50% in the western world. The exact definition of dyspepsia is elusive, which has resulted in confusion about diagnosis and treatment, highlighting the need for management guidelines. The International Gastro Primary Care Groups (IGPCG) has developed, by consensus, practical guidelines to help GPs manage patients with upper GI symptoms. After a detailed history is taken, alarm symptoms identified and organic disease excluded, the predominant symptom should be identified. This strategy, as outlined in the IGPCG upper GI disease management plan, can help the GP in the selection of the most appropriate treatment for each patient. This plan is flexible enough to be used in a wide variety of healthcare systems and will evolve as new evidence becomes available.

Disposable film cover for the tip of Goldmann's tonometer.

The application of a thin, transparent, polyvinylchloride film on the double prism of Goldmann's tonometer is proposed, so as to prevent bacterial and viral infection during tonometry. This film, mounted in such a way as to facilitate its application, is supplied in disposable sterile packaging. The use of the film does not alter the calibration of the instrument and does not substantially modify readings thereby obtained.