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The present work combines experiment and theory to reveal the behavior of bromo-substituted-biphenyls after an electron attachment. We experimentally determine anion lifetimes using an electron attachment-magnetic sector mass spectrometer instrument. Branching ratios of dissociative electron attachment fragments on longer timescales are determined using the electron attachment-quadrupole mass spectrometer instrument. In all cases, fragmentation is low: Only the Br- and [M-Br]- ions are detected, and [M-H]- is observed only in the case of 4-Br-biphenyl and parent anion lifetimes as long as 165 µs are observed. Such lifetimes are contradictory to the dissociation rates of 2- and 4-bromobiphenyl, as measured by the pulse radiolysis method to be 3.2 × 1010 and >5 × 1010 s-1, respectively. The discrepancy is plausibly explained by our calculation of the potential energy surface of the dissociating anion. Isolated in vacuum, the bromide anion can orbit the polarized aromatic radical at a long distance. A series of local minima on the potential energy surface allows for a roaming mechanism prolonging the detection time of such weakly bound complex anions. The present results illuminate the behavior recently observed in a series of bromo-substituted compounds of biological as well as technological relevance.

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Electron attachment to the 4-bromobiphenyl molecule and the decay channels of its molecular anion were investigated by means of Dissociative Electron Attachment (DEA) spectroscopy with two different spectrometers. The first apparatus is equipped with a static magnet mass analyzer (Ufa group) and the second one with a quadrupole mass filter (Prague group). The dominant DEA channel at low electron energy leads to formation of Br- negative fragments. Long-lived (τa = 40 µs at the temperature of 80 °C) molecular negative ions were detected only in the Ufa experiment. We explored the involved potential energy surfaces and found that the molecular anion has two distinct structures with the C-Br distances of 1.92 Å and 2.8 Å. The statistical model based on the Arrhenius approximation fully explains the experimental observations and sheds light on the earlier anion dissociation kinetic studies in solution.

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Phthalide, the simplest chain of conductive polymer thin film, was investigated by means of Electron Transmission Spectroscopy, Negative Ion Mass Spectrometry, and density functional theory quantum chemistry. It has been found that formation of gas-phase long-lived molecular anions of phthalide around 0.7 eV takes place through cleavage of a C-O bond of the pentacyclic ring of the parent molecular anion to give a vibrationally excited (electronically more stable) open-ring molecular anion. The energy of the transition state for ring opening of the parent negative ion is calculated to be 0.65 eV above the neutral ground state of the molecule. The energy (2.64 eV) evaluated for the corresponding transition state in the neutral molecule is much higher, so that the process of electron detachment from the anion must lead to a neutral molecule with its initial pentacyclic structure. The average lifetime of the molecular negative ions formed at an electron energy of 0.75 eV and 80 °C is measured to be about 100 µs. The known switching effect of thin phthalide films could stem from the presence of a similar open/closed transition state also in the polymer.

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RATIONALE: Electron Affinity (EA) is one of the fundamental properties of a molecule. EA values can be measured with various experimental methods, although their availability is still relatively limited. We make an attempt to use Dissociative Electron Attachment Spectroscopy (DEAS) data for evaluation of the EAs of twelve naphthoquinone (NQ) derivatives. METHODS: Naphthoquinone (NQ) and eleven of its hydroxyl derivatives were investigated by means of DEAS. A combined investigation of NQ and juglone by means of the Electron Transmission Spectroscopy (ETS) and DEAS techniques, with the support of density functional theory (DFT) calculations, allowed us to elucidate the empty-level structures of NQ and its hydroxyl derivatives. RESULTS: All molecules under investigation form extremely long-lived molecular anions associated with three resonant states (except for NQ, where only two long-lived resonances were observed). The hydroxyl substituents of NQ cause an increase in EA and number of internal degrees of freedom (N), and, as a result, an increase in the mean electron autodetachment lifetimes of the molecular negative ions (NIs). Evaluation of the EAs from the measured lifetimes of the molecular NIs through a simple Arrhenius approximation gives results in reasonable agreement with those obtained with DFT calculations. CONCLUSIONS: NI lifetime measurements by means of a modified DEAS instrumentation can provide quantitative data of EA. A simple Arrhenius approximation seems to be adequate to describe the process of electron detachment from molecular anions.

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While general cervical carcinoma morbidity is on the decline in most of the surveyed Russian Federation areas characterized by varying levels of industrial pollution, the heavily industrialized region of Salavat revealed a different tendency. Its level was 1.6 times (p<0.05) those in other areas. That was due to the morbidity of women aged 40-69 and even 20-29 and 30-39 years.

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In 45% of 212 cases of diphtheria toxica in adults heart complications were observed. The earliest ECG signs are sinus bradycardia, AV dissociation, AV escape rhythms, prolongation of QT interval, high U wave (U > T, T + U wave). In the cases where differential diagnosis of myocarditis and other heart diseases in adults is difficult, the attention must be focused on the sickle-like depression ("sagging") of ST-interval that is a typical sign in diphtheric myocarditis. The most severe forms of diphtheric myocarditis are complicated by AV and intraventricular conduction disturbances and malignant ventricular arrhythmias.

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High incidence of diphtheria became a pressing problem in recent years. The age structure of patients has changed. A specific feature of diphtheria in adults is a high share of toxic forms and a higher incidence of grave combined forms and rare localizations of the disease focus. The oral cavity proper is one of rare localizations of this infection. The authors examined 12 patients in whom the process was localized in various parts of the buccal mucosa: on the upper and lower lips, on the hard and soft palate, on the cheeks and tongue. Morphologic disturbances presenting as necrosis and inflammatory infiltration were detected in sites involved in the diphtheritic process. Changes whose manifestation was related to the diseases severity were found in zones adjacent to the foci. The authors come to a conclusion on a higher incidence of heretofore rare localizations of diphtheria than previously, this making difficult the diagnosis and treatment of the disease.

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As many as 33 children with different patterns of tachyarrhythmia were subjected to transesophageal pacing of the left atrium. Thi incidence of the orthodromal pattern of reciprocal AV-tachycardia was the highest (10 patients); antidromal reciprocal AV-tachycardia was only noted in 1 patient. Four patients turned out to have latent Kent's bundle which provoked the development of tachycardia attacks. The slow-fast pattern was revealed in both cases of nodal tachycardia. Among atrial tachycardias, monofocal automatic one was encountered most frequently (9 patients) and only one patient was diagnosed to suffer from reciprocal atrial tachycardia. The determination of the pathogenesis of tachycardia in children with the WPW syndrome is of importance for solving the problem of the successive medicamentous and non-pharmacological treatment character.

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