RASPT2 Analysis of the F-(H2O) n=1-7 and OH-(H2O) n=1-7 CTTS States.

We analyze the electronic structure of the lowest excited states of the F-(H2O) n=1-7 and OH-(H2O) n=1-7 anionic clusters in the framework of RASPT2 theory. At the ground-state geometry, these clusters can bind the excess electron in the first excited singlet and triplet states for n ≥ 3 for F- and n ≥ 2 for OH-. The geometry relaxation of the F-(H2O) n=1-7 clusters in their lowest-energy triplet state produces two series of minima. A first series is made of a F radical weakly bound to a negatively charged water cluster to form F-(H2O) n-. A second series associated with hydrogen transfer from a water molecule to the fluorine atom is built on a HF molecule and a OH radical bound to a negatively charged water cluster to form OH-HF-(H2O) n-1-. This second series provides the lowest-energy isomers of F-(H2O) n for the excited state. These two series of minima are inherited from the neutral fluorine water cluster structure only weakly perturbed by the excess electron. They are similar to the OH-(H2O) n isomers obtained for the lowest-energy triplet state, which are also made of a neutral OH radical inserted in the water molecule network of a (H2O) n- cluster. For all of these clusters in the lowest-energy excited state, the excess electron is localized outside of the cluster near unbound hydrogen atoms. Its binding energy is well correlated to the electric dipole of the cluster, and a lower limit of 4.1 D is necessary to bind it to the cluster. The two series of F-(H2O) n isomers offer two very different routes for geminate recombination observed in water solutions. Our calculation suggests that the recombination takes place with the OH radical left after hydrogen transfer rather than with the F radical.

Dissociation of GaN2+ and AlN2+ in APT: Electronic structure and stability in strong DC field.

We investigate from a theoretical point of view the stability of AlN2+ and GaN2+ dications produced under high static electric fields like those reached in Atom Probe Tomography (APT) experiments. By means of quantum chemical calculations of the electronic structure of these molecules, we show that their stability is governed by two independent processes. On the one hand, the spin-orbit coupling allows some molecular excited states to dissociate by inter-system crossing. On the other hand, the action of the electric field lowers the potential energy barrier, which ensures the dication stability in standard conditions. We present a detailed example of field emission dynamics in the specific case of the 11Δ states for a parabolic tip, which captures the essentials of the process by means of a simplified model. We show that the dissociation dynamics of AlN2+ and GaN2+ is completely different despite the strong resemblance of their electronic structure.

Dissociation of GaN2+ and AlN2+ in APT: Analysis of experimental measurements.

The use of a tip-shaped sample for the atom probe tomography technique offers the unique opportunity to analyze the dynamics of molecular ions in strong DC fields. We investigate here the stability of AlN2+ and GaN2+ dications emitted from an Al0.25Ga0.75N sample in a joint theoretical and experimental study. Despite the strong chemical resemblance of these two molecules, we observe only stable AlN2+, while GaN2+ can only be observed as a transient species. We simulate the emission dynamics of these ions on field-perturbed potential energy surfaces obtained from quantum chemical calculations. We show that the dissociation is governed by two independent processes. For all bound states, a mechanical dissociation is induced by the distortion of the potential energy surface in the close vicinity of the emitting tip. In the specific case of GaN2+, the relatively small electric dipole of the dication in its ground 13Σ- and excited 11Δ states induces a weak coupling with the electric field so that the mechanical dissociation into Ga+ + N+ lasts for sufficient time to be observed. By contrast, the AlN2+ mechanical dissociation leads to Al2+ + N which cannot be observed as a correlated event. For some deeply bound singlet excited states, the spin-orbit coupling with lower energy triplet states gives another chance of dissociation by system inter-system crossing with specific patterns observed experimentally in a correlated time of flight map.

Role of a Neighbor Ion in the Fragmentation Dynamics of Covalent Molecules.

Fragmentation of molecular nitrogen dimers (N_{2})_{2} induced by collision with low energy 90 keV Ar^{9+} ions is studied to evidence the influence of a molecular environment on the fragmentation dynamics of N_{2} cations. Following the capture of three or four electrons from the dimer, the three-body N_{2}^{+}+N^{m+}+N^{n+} [with (m,n)=(1,1) or (1, 2)] fragmentation channels provide clean experimental cases where molecular fragmentation may occur in the presence of a neighbor molecular cation. The effect of the environment on the fragmentation dynamics within the dimer is investigated through the comparison of the kinetic energy release (KER) spectra for these three-body channels and for isolated N_{2}^{(m+n)+} monomer cations. The corresponding KER spectra exhibit energy shifts of the order of 10 eV, attributed to the deformation of the N^{m+}+N^{n+} potential energy curves in the presence of the neighboring N_{2}^{+} cation. The KER structures remain unchanged, indicating that the primary collision process is not significantly affected by the presence of a neighbor molecule.

Electronic structure and stability of the SiO2+ dications produced in tomographic atom probe experiments.

The molecular electronic states of the SiO2+ dication have been investigated in a joint theoretical and experimental analysis. The use of a tip-shaped sample for tomographic atom probe analysis offers the unique opportunity to produce and to analyze the lifetime of some excited states of this dication. The perturbation brought by the large electric field of the polarized tip along the ion trajectory is analyzed by means of molecular dynamics simulation. For the typical electric fields used in the experiment, the lowest energy triplet states spontaneously dissociate, while the lowest energy singlet states do not. We show that the emission process leads to the formation of some excited singlet state, which dissociates by means of spin-orbit coupling with lower-energy triplet states to produce specific patterns associated with Si+ + O+ and Si2+ + O dissociation channels. These patterns are recorded and observed experimentally in a correlated time-of-flight map.

Spin-orbit coupling in the dissociative excitation of alkali atoms at the surface of rare gas clusters: A theoretical study.

We analyze the role of the spin-orbit (SO) coupling in the dissociative dynamics of excited alkali atoms at the surface of small rare gas clusters. The electronic structure of the whole system is deduced from a one-electron model based on core polarization pseudo-potentials. It allows us to obtain in the same footing the energy, forces, and non-adiabatic couplings used to simulate the dynamics by means of a surface hopping method. The fine structure state population is analyzed by considering the relative magnitude of the SO coupling ξ, with respect to the spin-free potential energy. We identify three regimes of ξ-values leading to different evolution of adiabatic state population after excitation of the system in the uppermost state of the lowest np (2)P shell. For sufficiently small ξ, the final population of the J=12 atomic states, P12, grows up linearly from P12=13 at ξ = 0 after a diabatic dynamics. For large values of ξ, we observe a rather adiabatic dynamics with P12 decreasing as ξ increases. For intermediate values of ξ, the coupling is extremely efficient and a complete transfer of population is observed for the set of parameters associated to NaAr3 and NaAr4 clusters.

Nonadiabatic molecular dynamics of photoexcited Li2(+) Ne(n) clusters.

We investigate the relaxation of photoexcited Li(2)(+) chromophores solvated in Ne(n) clusters (n = 2-22) by means of molecular dynamics with surface hopping. The simplicity of the electronic structure of these ideal systems is exploited to design an accurate and computationally efficient model. These systems present two series of conical intersections between the states correlated with the Li+Li(2s) and Li+Li(2p) dissociation limits of the Li(2)(+) molecule. Frank-Condon transition from the ground state to one of the three lowest excited states, hereafter indexed by ascending energy from 1 to 3, quickly drives the system toward the first series of conical intersections, which have a tremendous influence on the issue of the dynamics. The states 1 and 2, which originate in the Frank-Condon area from the degenerated nondissociative 1(2)Π(u) states of the bare Li(2)(+) molecule, relax mainly to Li+Li(2s) with a complete atomization of the clusters in the whole range of size n investigated here. The third state, which originates in the Frank-Condon area from the dissociative 1(2)Σ(u)(+) state of the bare Li(2)(+) molecule, exhibits a richer relaxation dynamics. Contrary to intuition, excitation into state 3 leads to less molecular dissociation, though the amount of energy deposited in the cluster by the excitation process is larger than for excitation into state 1 and 2. This extra amount of energy allows the system to reach the second series of conical intersections so that approximately 20% of the clusters are stabilized in the 2(2)Σ(g)(+) state potential well for cluster sizes n larger than 6.

Spectroscopic properties of alkali atoms embedded in Ar matrix.

We present a theoretical investigation of visible absorption and related luminescence of alkali atoms (Li, Na, and K) embedded in Ar matrix. We used a model based on core polarization pseudopotentials, which allows us to determine accurately the gas-to-matrix shifts of various trapping sites. The remarkable agreement between our calculated results and the experimental spectra recorded by several authors allows us to establish a clear assignment of the observed spectra, which are made of contributions from crystalline sites on the one hand, and of grain boundary sites on the other hand. Our study reveals remarkably large Stokes shifts, up to 9000 cm(-1), which could be observed experimentally to identify definitely the trapping sites.

Structure and photoabsorption properties of cationic alkali dimers solvated in neon clusters.

We present a theoretical investigation of the structure and optical absorption of M(2)(+) alkali dimers (M=Li,Na,K) solvated in Ne(n) clusters for n=1 to a few tens Ne atoms. For all these alkali, the lowest-energy isomers are obtained by aggregation of the first Ne atoms at the extremity of the alkali molecule. This particular geometry, common to other M(2)(+)-rare gas clusters, is intimately related to the shape of the electronic density of the X (2)Σ(g)(+) ground state of the bare M(2)(+) molecules. The structure of the first solvation shell presents equilateral Ne(3) and capped pentagonal Ne(6) motifs, which are characteristic of pure rare gas clusters. The size and geometry of the complete solvation shell depend on the alkali and were obtained at n=22 with a D(4h) symmetry for Li and at n=27 with a D(5h) symmetry for Na. For K, our study suggests that the closure of the first solvation shell occurs well beyond n=36. We show that the atomic arrangement of these clusters has a profound influence on their optical absorption spectrum. In particular, the XΣ transition from the X (2)Σ(g)(+) ground state to the first excited (2)Σ(u)(+) state is strongly blueshifted in the Frank-Condon area.

An accurate model potential for alkali neon systems.

We present a detailed investigation of the ground and lowest excited states of M-Ne dimers, for M=Li, Na, and K. We show that the potential energy curves of these Van der Waals dimers can be obtained accurately by considering the alkali neon systems as one-electron systems. Following previous authors, the model describes the evolution of the alkali valence electron in the combined potentials of the alkali and neon cores by means of core polarization pseudopotentials. The key parameter for an accurate model is the M(+)-Ne potential energy curve, which was obtained by means of ab initio CCSD(T) calculation using a large basis set. For each MNe dimer, a systematic comparison with ab initio computation of the potential energy curve for the X, A, and B states shows the remarkable accuracy of the model. The vibrational analysis and the comparison with existing experimental data strengthens this conclusion and allows for a precise assignment of the vibrational levels.

Solvation of Na(2) (+) in Ar(n) clusters. I. Structures and spectroscopic properties.

We present a theoretical study of Na(2) (+) solvation in an argon matrix Ar(n) for n=1 to a few tens. We use a model based on an explicit description of valence electron interaction with Na(+) and Ar cores by means of core polarization pseudopotential. The electronic structure determination is thus reduced to a one-electron problem, which can be handled efficiently. We investigate the ground state geometry and related optical absorption of Na(2) (+)Ar(n) clusters. For nA (2)Sigma(u) (+)), which reveals the confinement of the excited A (2)Sigma(u) (+) state. The Na(2) (+) energy spectrum is so strongly perturbed that the A (2)Sigma(u) (+) state becomes higher than the B (2)Pi(u) (+) states. The closure of the first solvation shell is observed at n=17. Above this size, the second solvation shell develops. Its structure is dominated by a pentagonal organization around the Na(2) (+) molecular axis. The optical transitions vary smoothly with n and the A (2)Sigma(u) (+) and B (2)Pi(u) states are no longer inverted, though the first optical transition remains strongly blueshifted.

Secondary neoplastic infiltration of the myocardium diagnosed by two-dimensional echocardiography in seven cases with anatomic confirmation.

In seven patients with different types of neoplasm, secondary myocardial infiltration was diagnosed in vivo by two-dimensional echocardiography and confirmed by direct inspection. In all patients, clinical and electrocardiographic findings were suggestive but nonspecific for myocardial involvement. Two patients had cardiac tamponade and three had pericardial effusion. In three patients, the echocardiographic diagnosis made it possible to plan specific therapy. Clinical, electrocardiographic and echocardiographic aspects are discussed. A two-dimensional echocardiographic examination should be performed in all patients when cardiac metastatic involvement is suspected from clinical electrocardiographic findings, because the in vivo diagnosis of such a condition may have important therapeutic implications for such patients.

PAIMS 2: alteplase combined with heparin versus heparin in the treatment of acute pulmonary embolism. Plasminogen activator Italian multicenter study 2.

BACKGROUND: The effect of alteplase versus heparin in pulmonary embolism has not been studied extensively with serial pulmonary angiograms. OBJECTIVES: The aim of this randomized, open trial was to evaluate the efficacy and safety of alteplase followed by heparin, versus heparin alone, in 36 patients with angiographically documented pulmonary embolism. METHODS: Twenty patients were allocated randomly to a 2-h infusion of alteplase (10 mg bolus, then 90 mg over 2 h) followed by heparin; the other 16 patients were given intravenous heparin at a continuous infusion rate of 1,750 IU/h. RESULTS: The vascular obstruction, assessed by the Miller index at pulmonary angiography, decreased significantly in alteplase-treated patients (p less than 0.01) from a baseline of 28.3 +/- 2.9 to a value of 24.8 +/- 5.2 2 h after the start of infusion; in the heparin group there was no change (from 25.3 +/- 5.3 to 25.2 +/- 5.4). Mean pulmonary artery pressure decreased significantly from a baseline of 30.2 +/- 7.8 mm Hg to 21.4 +/- 6.7 in the alteplase group and increased in the heparin group (from 22.3 +/- 10.5 to 24.8 +/- 11.2 mm Hg). For a subset of patients, lung scans were performed at baseline and on days 7 and 30. There were no differences between the two groups in the follow-up lung scans, but there were significant decreases from the baseline values. Bleeding occurred in 14 of 20 alteplase-treated patients and in 6 of 16 in the heparin group (p = NS). There were three major bleeding episodes in the alteplase group and two in the heparin group. Two patients died after fibrinolysis (one of acute renal failure after cardiac tamponade and one of cardiac arrest after cerebral hemorrhage) and one patient in the heparin group died of recurrent pulmonary embolism. CONCLUSIONS: Alteplase resulted in a greater and faster improvement of the angiographic and hemodynamic variables compared with heparin. However, the high frequency of bleeding observed with alteplase in this trial suggests that patients should be carefully selected before thrombolytic therapy is given.

[Influence of sex on the prognosis of high risk acute coronary syndromes treated by early angioplasty]. / Influence du sexe sur le pronostic des syndromes coronaires aigus à haut risque traités par angioplastie précoce.

The aim of this study was to evaluate the influence of sex on the prognosis of high risk acute coronary syndromes treated early with angioplasty. Over a period of two years, 694 consecutive patients (151 female, 543 male) underwent revascularisation within the first 24 hours of an acute coronary syndrome without permanent ST elevation (ST depression (52.5%) or relapse of angina despite medical treatment (47.5%). The females were older than the males (67.9 vs 62.3 years; p < 0.0001), smoked less (7.3 vs. 32.8%; p < 0.001) and had a higher prevalence of hypertension (53 vs. 42.1%; p = 0.017). The angiographic characteristics were equivalent in both sexes, except for a lower frequency of thrombus in the females (6.9 vs. 15.2%; p < 0.0001). All lesions were treated with endoprosthesis implantation. The angiographic success rate was comparable (94 vs. 93.7%) as was the rate of major cardiac events while in hospital (3.8 versus 4%). With an average survival of 2 years, the incidence of major cardiac events remained identical in both sexes (15.4 vs 15.7%: p = 0.43): cardiac mortality (3.2 vs 2%; p = 0.18), myocardial infarction (7.3 vs 6.7%; p = 0.37), further revascularisation (8.3 vs 7.2%; p = 0.47). The survival without major cardiac event was comparable at 1 year (87 +/- 0.1 vs 88 +/- 0.3%) and at 2 years (78 +/- 0.2 vs 83 +/- 0.3%; p = 0.58). In conclusion, the progression both in hospital and at two years with a strategy of early revascularisation for high risk acute coronary syndromes was comparable in males and females.

Sodium-lithium countertransport and cardiorenal abnormalities in essential hypertension.

The rate of red blood cell sodium-lithium countertransport is elevated only in a subgroup of patients with essential hypertension. We have therefore compared renal and cardiac function and morphology in two groups of hypertensive patients with high (n = 23) or normal (n = 22) sodium-lithium countertransport (mean +/- SEM: 0.61 +/- 0.10 versus 0.29 +/- 0.07 mmol/l red blood cells.hr). The two groups were similar in age, sex distribution, body mass index, smoking habit, duration of hypertension, and actual levels of untreated blood pressure. Hypertensive patients with elevated sodium-lithium countertransport activity showed elevated glomerular filtration rate (118 +/- 2 versus 109 +/- 2 ml/min.1.73 m2; p less than 0.001), albumin excretion rate (23 +/- 3 versus 14 +/- 2 micrograms/min; p less than 0.001), larger kidney volume (250 +/- 15 versus 203 +/- 13 ml.1.73 m2; p less than 0.01), lower lithium clearance rate (26.7 +/- 0.3 versus 28.9 +/- 0.3 ml/min.1.73 m2; p less than 0.01), and higher total body exchangeable sodium (2,716 +/- 33 versus 2,485 +/- 41 mmol.1.73 m2; p less than 0.01). Left ventricular mass index (139 +/- 6 versus 119 +/- 6 g/m2; p less than 0.05), relative wall thickness (0.39 +/- 0.05 versus 0.29 +/- 0.04 cm; p less than 0.001), and left posterior wall plus intraventricular septum thickness (2.02 +/- 0.04 versus 1.76 +/- 0.03 cm; p less than 0.05) were also higher in patients with high sodium-lithium countertransport. Hypertensive patients with normal sodium-lithium countertransport had renal and cardiac parameters similar to those of a normotensive control group (n = 21) except for a higher glomerular filtration rate and left ventricular mass index.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of transesophageal echocardiography in evaluation of paracardiac neoplastic masses.

Mediastinal paracardiac tumors may cause both cardiovascular complications and problems in differential diagnosis of cardiac diseases. Transesophageal echocardiography (TEE) may give an additional new window to mediastinal neoplasms, but only a few studies have been reported. TEE was performed in 70 patients with paracardiac neoplastic masses. The procedure was indicated to solve particular clinical problems in 20 patients, and as a prospective study on 50 unselected patients with mediastinal neoplasms. Twenty-three patients underwent follow-up studies; a total of 101 echocardiograms were recorded. The procedure was tolerated well or very well by most patients, and provided additional anatomic or hemodynamic data in every patient in group a and in 45 of 50 in group b. The additional data were relevant for clinical management in 14 of 20 patients in group a, and in 3 of 45 in group b. Based on the results of this study, TEE is useful in association with other radiologic techniques in patients with paracardiac neoplasms. As an imaging technique, it may represent a reliable alternative to computed tomography whenever the latter is not feasible.

Relation of right ventricular morphology and function in pectus excavatum to the severity of the chest wall deformity.

Although pectus excavatum (PE) is thought to impair right ventricular (RV) performance, the degree of RV dysfunction, if any, produced by this chest wall deformity remains controversial. To address this issue, we performed 2-dimensional echocardiography and chest wall radiography in 28 subjects with mild-to-severe degrees of PE to assess RV morphology and function in relation to the degree of the chest wall deformity. Measurements of RV anatomy and function obtained in these patients were compared to those of 24 normal control subjects of similar age and sex. In subjects with PE, mean RV outflow tract diameter at the aortic root level was narrower (1.4 +/- 0.3 cm/m2) and end-diastolic (10 +/- 2.3 cm2/m2) and end-systolic (5.8 +/- 1.4 cm2/m2) areas were larger than those in normal controls (1.6 +/- 0.3, 8.6 +/- 1.7, and 4.5 +/- 1.2 cm2/m2, respectively; p < 0.013). The magnitude of these abnormalities was related to the degree of the chest wall deformity evaluated on the chest radiogram (r = 0.54, 0.51, and 0.49, respectively). RV planar emptying fraction, an index of RV systolic function, was reduced in subjects with PE (42 +/- 10%) compared to the normal controls (48 +/- 10%; p = 0.047). No relation could be found, however, between this index and the severity of the chest wall deformity.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of transesophageal echocardiography in evaluation of pulmonary venous obstruction by paracardiac neoplastic masses.

From 71 consecutive patients with paracardiac neoplastic masses who underwent transesophageal echocardiography (TEE), obstruction of individual right upper pulmonary venous flow by compression by contiguous mass was detected by TEE in 4 patients before and disappeared after anti-neoplastic treatments. Pulmonary vein, contiguous neoplastic mass and their relation could be clearly visualized and assessed by TEE. Pulmonary venous obstruction was assessed as moderate degree by combination of Doppler flow characteristics and diameter of pulmonary vein. Before therapy, peak velocities and time-velocity integrals in obstructed right upper pulmonary venous flow were increased, whereas deceleration times of systolic flow were prolonged. After therapy, peak velocities and time-velocity integrals were reduced and deceleration times of systolic flow were shortened, with normalization of the diameter of the right upper pulmonary veins. Thus, TEE may be used to detect and evaluate pulmonary venous obstruction by neoplastic masses and its changes after antineoplastic treatments.

Sensitivity and specificity of electrocardiographic ST-T changes as markers of neoplastic myocardial infiltration. Echocardiographic correlation.

We evaluated the correlations between electrocardiographic ST-T changes (negative T waves, ST segment elevation) and echocardiographic diagnosis of neoplastic infiltration of the myocardium in 95 patients with neoplastic masses in contact with the heart. We compared echocardiographic results to computed tomography, nuclear magnetic resonance, surgery or autopsy data in 49 patients: the concordance was 86 percent. Significant ST-T changes were present in 77.7 percent of the patients with myocardial infiltration at echocardiography. The "false negatives" (normal ECG, nonspecific changes) were mainly related to infiltration limited to the right side of the heart; in some of these cases, the appearance of right bundle branch block was observed. The "false positives" (ST-T changes without echocardiographic signs of infiltration) were observed in the older patients and in those with pericardial effusion or other heart diseases. The ST segment elevation was a more specific sign of myocardial infiltration as compared to negative T waves (86 vs 47 percent). A progression or the disappearance of electrocardiographic and echocardiographic abnormalities was observed during follow-up in 24 cases. Serial electrocardiograms are useful for screening in clinical settings in neoplastic patients; the appearance of ST-T changes or of conduction disturbances should suggest the need for two-dimensional echocardiography in order to define the diagnosis.

M-mode and two-dimensional echocardiography in congenital absence of the pericardium.

The M-mode and two-dimensional echocardiographic features of congenital absence of the pericardium are described in two cases that had been confirmed by clinical and radiological data. The M-mode echocardiogram showed right ventricular dilatation and abnormal systolic motion of the interventricular septum. Echo contrast studies with peripheral injection of saline solution revealed normal persistence of microbubbles in the right side of the heart. Two-dimensional short axis parasternal views showed some dilatation of the right ventricle, with anterior displacement of the left ventricular cavity in systole, which appeared to be wider than the posterior motion of the interventricular septum towards the posterior wall. The resulting positive motion of the interventricular septum toward the transducer could account for the abnormal pattern seen in the M-mode echocardiogram. Congenital absence of the left pericardium has particular echocardiographic features not diagnostic for the anomaly. However, the M-mode and two-dimensional echocardiographic studies, used in conjunction with the echocontrast techniques, seem to help in the differential diagnosis and for excluding associated anomalies.