Spin-Dependent ππ

We present a detailed analysis of the electronic properties of graphene/Eu/Ni(111). By using angle- and spin-resolved photoemission spectroscopy and ab initio calculations, we show that the intercalation of Eu in the graphene/Ni(111) interface gives rise to a gapped freestanding dispersion of the ππ^{*} Dirac cones at the K[over ¯] point with an additional lifting of the spin degeneracy due to the mixing of graphene and Eu states. The interaction with the magnetic substrate results in a large spin-dependent gap in the Dirac cones with a topological nature characterized by a large Berry curvature and a spin-polarized Van Hove singularity, whose closeness to the Fermi level gives rise to a polaronic band.

Synthesis of mesoscale ordered two-dimensional π-conjugated polymers with semiconducting properties.

Two-dimensional materials with high charge carrier mobility and tunable band gaps have attracted intense research effort for their potential use in nanoelectronics. Two-dimensional π-conjugated polymers constitute a promising subclass because the band structure can be manipulated by varying the molecular building blocks while preserving key features such as Dirac cones and high charge mobility. The major barriers to the application of two-dimensional π-conjugated polymers have been the small domain size and high defect density attained in the syntheses explored so far. Here, we demonstrate the fabrication of mesoscale ordered two-dimensional π-conjugated polymer kagome lattices with semiconducting properties, Dirac cone structures and flat bands on Au(111). This material has been obtained by combining a rigid azatriangulene precursor and a hot dosing approach, which favours molecular diffusion and eliminates voids in the network. These results open opportunities for the synthesis of two-dimensional π-conjugated polymer Dirac cone materials and their integration into devices.

Resonant circular dichroism of chiral metal-organic complex.

A sizable enhancement of the circular dichroism in photoelectron spectroscopy has been measured and computed for the metal complex Δ-cobalt(III) tris-acetylacetonate highest occupied molecular orbital state in the region of the Co 3p→3d Fano resonance. In the resonance the dichroism reaches the maximum value of 5% and even changes its sign as compared to the direct photoionization channel. We ascribe this enhancement to electron correlation processes, namely, with the coupling between discrete excitations and the continuum, which is correctly described in the time dependent density functional theory (TDDFT) framework. These findings open new physical aspects of photoelectron circular dichroism that now can be interpreted not only via the simple direct ionization, but also through more complex electron correlation processes.

Binding geometry of hydrogen-bonded chain motif in self-assembled gratings and layers on Ag(111).

Upon adsorption on the (111) facet of Ag, 4-[trans-2-(pyrid-4-yl-vinyl)] benzoic acid (PVBA) self-assembles into a highly ordered, chiral twin chain structure at submonolayer coverages with domains that can extend for micrometers in one dimension. Using polarization-dependent measurements of C and N K-shell excitations in near-edge X-ray absorption fine structure (NEXAFS) spectra, we determine the binding geometry of single PVBA molecules within this unique ensemble for both low and high coverage regimes. At submonolayer coverage, the molecule is twisted to facilitate the formation of hydrogen bonds. The gas-phase planarity is gradually recovered as the coverage is increased, with complete planarity coinciding with loss of order in the overlayer. Thermal treatment of the PVBA film results in deprotonation of the carboxyl tail of the molecule, but despite the suppression of the stabilizing hydrogen-bonds, the overlayer remains ordered.

Chirality transfer from a single chiral molecule to 2D superstructures in alaninol on the Cu(100) surface.

The formation of 2D chiral monolayers obtained by self-assembly of chiral molecules on surfaces has been widely reported in the literature. Control of chirality transfer from a single molecule to surface superstructures is a challenging and important aspect for tailoring the properties of 2D nanostructures. However, despite the wealth of investigations performed in recent years, how chiral transfer takes place on a large scale still remains an open question. In this paper we report a coupling of scanning tunneling microscopy and low energy electron diffraction measurements with an original theoretical approach, combining molecular dynamics and essential dynamics with density functional theory, to investigate self-assembled chiral structures formed when alaninol adsorbs on Cu(100). The peculiarity of this system is related to the formation of tetrameric molecular structures which constitute the building blocks of the self-assembled chiral monolayer. Such characteristics make alaninol/Cu(100) a good candidate to reveal chiral expression changes. We find that the deposition of alaninol enantiomers results in the formation of isolated tetramers that are aligned along the directions of the substrate at low coverage or when geometrical confinement prevents long-range order. Conversely, a rotation of 14° with respect to the Cu(100) unit vectors is observed when small clusters of tetramers are formed. An insight to the process leading to a 2D globally chiral surface has been obtained by monitoring molecular assemblies as they grow from the early stages of adsorption, suggesting that the distinctive orientation of the self-assembled monolayer originates from a balance of cooperating forces which start acting only when tetramers pack together to form small clusters.

The valence electronic structure and conformational flexibility of epichlorohydrin.

The electronic structure of epichlorohydrin is investigated in the whole valence region by a combined experimental and theoretical study. The issue of controversial assignments of the molecular electronic structure is here addressed. Photoelectron spectra (PES) and Threshold Photoelectron spectra (TPES) of room temperature molecules in the gas phase are recorded. Geometries and energies of the stable conformers due to internal rotation of the C-C-C-Cl dihedral angle, gauche-II (g-II), gauche-I (g-I), and cis, are calculated, and the effect of the conformational flexibility on the photoionization energetics is studied by DFT and 2h-1p Configuration Interaction (CI) methods. Strong breakdown of the Koopmans Theorem (KT) is obtained for the four outermost ionizations, which are further investigated by higher level ab initio calculations. The full assignment of the spectrum is put on a firm basis by the combination of experimental and theoretical results. The orbital composition from correlated calculations is found closer to the DFT orbitals, which are then used to analyze the electronic structure of the molecule. The Highest Occupied Molecular Orbital (HOMO) and HOMO--2 are n(O)/n(Cl) mixed orbitals. The nature of each valence MO is generally preserved in all the conformers, although the magnitude of the n(O)/n(Cl) mixing in HOMO and HOMO--2 varies to some extent with the C-C-C-Cl dihedral angle. The low energy part of the HOMO PE band is predicted to be substantially affected by the conformational flexibility, as experimentally observed in the spectra. The rest of the spectrum is described in terms of the dominant conformer g-II, and a good agreement between experiment and theory is found. The inner-valence PE spectrum is characterized by satellite structures, due to electron correlation effects, which are interpreted by means of 2h-1p CI calculations.

Temperature-induced molecular reorganization on Au(111) driven by oligomeric defects.

The formation of ordered molecular structures on surfaces is determined by the balance between molecule-molecule and molecule-substrate interactions. Whether the aggregation process is guided by non-covalent forces or on-surface reactions, a deeper understanding of these interactions is pivotal to formulating a priori predictions of the final structural features and the development of bottom-up fabrication protocols. Theoretical models of molecular systems corroborate the information gathered through experimental observations and help explain the thermodynamic factors that underpin on-surface phase transitions. Here, we report a scanning tunneling microscopy investigation of a tribromo-substituted heterotriangulene on the Au(111) surface, which initially forms an extended close-packed ordered structure stabilized by BrBr halogen bonds when deposited at room temperature. X-ray photoelectron spectroscopy reveals that annealing the self-assembled layer induces a fraction of the molecular precursors to partially dehalogenate that in turn leads to the formation of a less stable BrO non-covalent network which coexists with the short oligomers. Density functional theory (DFT) and Monte Carlo (MC) simulations illustrate how dimer moieties act as defects whose steric hindrance prevents the retention of the more stable configuration. A small number of dimers is sufficient to drive the molecular reorganization into a lower cohesive energy phase. Our study shows the importance of a combined DFT - MC approach to understand the evolution of molecular systems on substrates.

Cardiovascular effects of a single high dose of dilazep by oral route.

The acute hemodynamic effects on the coronary and systemic arteries of a single high dose of dilazep given orally (200-400 mg; 3-5 mg/kg) were studied in 25 anginal patients who, for diagnostic reasons, underwent cardiac catheterization and coronary angiography. From 20 to 30 min after drug administration, systemic vascular resistance (1666 +/- 348 to 1367 +/- 312 dyn X sec X cm-5, P less than 0.05) and left ventricular end-diastolic pressure (16.5 +/- 5 to 12 +/- 4.4 mm Hg, P less than 0.01) decreased significantly. The heart rate rose from 74 +/- 10 to 84 +/- 12 beats/min (P less than 0.05), while the cardiac index, dp/dt max and pulmonary arteriolar resistance did not change significantly. Concomitantly, coronary blood flow significantly increased, coronary resistance was reduced by 42% (P less than 0.01) while myocardial oxygen consumption was unchanged. The increase in mean coronary arterial diameter was by 22-25%. It is concluded that dilazep has a prompt and potent vasodilating action even after oral administration. The drug is therefore useful in the chronic treatment of ischemic heart disease.

Myocardial indium-111 antimyosin uptake after uncomplicated coronary artery bypass surgery.

The prevalence of myocardial damage after coronary artery bypass grafting is related to the criteria of its evaluation. Indium-111 monoclonal antimyosin antibody scintigraphy has been shown to be highly sensitive and specific for even small areas of myocardial necrosis or injury like those of myocarditis or transplant rejection. Our purpose was to evaluate, by using this method, myocardial damage after uncomplicated coronary artery bypass grafting. Uptake of this radio tracer was evaluated after coronary artery bypass grafting in 14 informed and consenting consecutive patients without previous myocardial infarction, with no post-surgical complications and a favorable postoperative course, following coronary artery bypass grafting for stable angina pectoris. Monoclonal antimyosin antibody indium-111 74 MBq (Myoscint Centocor) was injected on the third postoperative day; planar images in the anterior, left anterior oblique 45 degrees and 70 degrees projections were obtained 24 and 48 h later and analyzed for myocardial uptake. Indium-111 antimyosin uptake was present in 10 out of 14 patients (71.4%); it was diffuse in 6 and localized in 4. The ratio of the maximal counts in the myocardium to the counts in the adjacent lung background was measured and found elevated: 1.94 +/- 0.23, higher than the normal values reported in the literature. Indium-111 antimyosin uptake was clear in a group of patients after uncomplicated coronary artery bypass grafting. No correlation was observed between indium-111 antimyosin uptake or heart to lung ratio and creatine kinase, creatine kinase isoenzyme MB, glutamic oxalacetic transferase levels, duration of cardiopulmonary bypass or aortic cross-clamp time, while elevated serum beta myosin heavy chain fragments (IRMA Pasteur) were observed (1378 +/- 238 microU/l). This study suggests that some degree of myocardial damage, though silent, is common after coronary artery bypass grafting.

Perioperative myocardial cell damage assessed by immunoradiometric assay of beta-myosin heavy chain serum levels in patients undergoing coronary bypass surgery.

In order to investigate myocardial cell damage in patients undergoing coronary bypass surgery, serum levels of cardiac myosin fragments, using monoclonal antibodies to myosin beta heavy chains, were measured in serial blood samples of 85 patients, 79 male and 6 female, 43-66 years old, after a total of 86 internal mammary artery and 137 saphenous vein graft implants. Eight patients had perioperative acute myocardial infarction (MI), detected by abnormal Q waves and a rise of CK-MB levels. After surgery, beta-myosin levels increased from post-operative day 3 and reached peak values on day 5 in patients without and in day 7 in patients with perioperative MI, in these 8 patients, myosin peak levels were greater as compared to 77 patients without perioperative MI (3452 +/- 1596 vs. 761 +/- 494; P < 0.01). There was a correlation between myosin peak levels and creatine kinase (CK) (r = 0.71; P < 0.05) and CK-MB peak levels (r = 0.74; P < 0.05) only in the patients with perioperative MI, but not in the patients without MI. There was no correlation between myosin peak levels and the times of aortic cross clamping or cardiopulmonary bypass. Peak myosin levels over 75% confidence limits of the mean were found in 23 patients; post-operative low output syndrome occurred in 10 of these 23 patients and in 7 out of 62 patients with peak myosin levels within 75% of the mean (P < 0.005). The increase in beta-myosin heavy chain serum levels observed in almost all patients undergoing coronary surgery suggests lesser perioperative damage of the contractile apparatus, which could be detected by the usual enzyme and ECG criteria. The higher prevalence of low output syndrome in patients with higher increases in myosin levels suggests more pronounced damage to the contractile apparatus in these patients. The higher myosin levels clearly indicate the presence of perioperative MI.

Exercise cardiovascular responses to gallopamil in ischemic heart disease.

UNLABELLED: In a single-blind, placebo-controlled, crossover trial versus diltiazem, we evaluated the influence of gallopamil on cardiovascular responses evoked by bicycle exercise. Twelve patients with chronic stable angina were enrolled. After a 5 days placebo run-in period, patients were randomly assigned either to gallopamil (50 mg thrice daily) or diltiazem (60 mg thrice daily) for 10 days. Then, patients were changed to the alternative drug. After placebo, and at the end of each subsequent period, all subjects underwent right heart catheterization by means of a Swan-Ganz thermodilution catheter. Hemodynamics were determined in 3 ways: supine, standing and during a multistage exercise test. RESULTS: anginal attacks were reduced to a similar degree by gallopamil (2.1 +/- 1/week versus 5.8 +/- 2.8/week during placebo, p less than 0.01) and diltiazem (2.0 +/- 0.8/week versus 5.8 +/- 2.8/week during placebo, P less than 0.01). At rest, gallopamil caused a significant decrease in heart rate and a slight fall in systemic vascular resistance. Cardiac index rose during exercise and was higher with respect to placebo at peak exercise (6.7 vs 5.6 l/min/m2, P less than 0.05). As a consequence, stroke volume index and stroke work index both increased at maximum workload (P less than 0.05). Compared to placebo, exercise time was significantly improved by gallopamil (+50%, P less than 0.02) and diltiazem (+38%, P less than 0.05). Likewise, time to onset of ST-segment depression was prolonged by 70% with gallopamil (P less than 0.01) and by 64% with diltiazem (P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Isolated and preclinical impairment of left ventricular filling in insulin-dependent and non-insulin-dependent diabetic patients.

BACKGROUND: Diabetes mellitus can induce a pattern of myocardial pathology known as specific diabetic cardiomyopathy, even if this is not clearly specified. HYPOTHESIS: The aim of our study was to evaluate the presence of preclinical myocardial damage in insulin- and non-insulin-dependent diabetic patients and controls by assessment with Doppler echocardiography. METHODS: Twenty insulin-dependent diabetic (IDDM) patients, 10 non-insulin-dependent diabetic (NIDDM) patients, and 12 healthy individuals (C) as controls, matched for age, gender, and without overt cardiovascular disease, were assessed in this study. RESULTS: Systolic function parameters presented normal values in the three groups, with the exception of a slight reduction in ventricular volume indices in the NIDDM group. Diastolic function was clearly impaired in both groups of patients versus that in healthy controls. In particular, ventricular filling was impaired in the NIDDM compared with the IDDM patients, especially the peak early filling rate E (p < 0.001). Moreover, in the IDDM group, the duration of diabetes (p < 0.01) and glycosilated hemoglobin value (HbA1C, p < 0.02) were higher than in the NIDDM group. Multiple regression analysis showed a significant inverse correlation between HbA1C and peak late filling rate A (R2 = 0.28) in both groups of patients and a direct correlation between velocity time integral E and age, duration of diabetes, and HbA1C (R2 = 0.46). The two groups presented a small, homogeneous number of cases with initial microangiopathy and borderline autonomic neuropathy, associated with microalbuminuria. Doppler echocardiography showed an early impairment of left ventricular filling, as well as an early preclinical alteration of myocardial function in diabetic patients, especially in the NIDDM group. CONCLUSION: These early signs of cardiomyopathy could constitute a predisposing condition toward the high cardiac morbidity and mortality rate in diabetic patients.

Surgical treatment of left main coronary stenosis. Notes on 179 consecutive patients.

The authors report the clinical haemodynamic and angiographic data and early and late postoperative results of 179 patients consecutively operated on for left main coronary artery stenosis. Operative mortality was 3.9%; incremental risk factors were identified by univariate analysis and included female sex, unstable angina pectoris and congestive heart failure. Late postoperative mortality was 4.9%. After a mean follow-up of 31 months overall survival is 91.6%; the great majority of survivors are doing well, free from anginal pain, while 16.4% of patients experience recurrent angina pectoris of lesser severity than before operation (I-II C.C.S. class) and well controlled by medical treatment alone.

[Right ventricular function before and 6 months after aortocoronary bypass. A radioisotope angiographic study]. / La funzione ventricolare destra prima e sei mesi dopo bypass aorto-coronarico. Studio angiografico radioisotopico.

The aim of the present paper is the study of the changes induced on right ventricular function after myocardial revascularization with aortocoronary bypass graft. Two-three days before and 6 months after operation gated radionuclide ventriculography has been performed in 25 patients with previous myocardial infarction (MI), anterior in 16 patients and inferior in 9. At postoperative examination, right ventricular ejection fraction (EF) was slightly but significantly reduced (p less than 0.01), while peak ejection and filling rates were unchanged. Symmetric parameters of left ventricular function did not show changes at post-operative control, except a clear-cut rise of left ventricular peak filling rate (p less than 0.05). Before operation, in patients with previous anterior MI, left ventricular EF was slightly less and right ventricular EF slightly more than in patients with previous inferior MI; after operation right ventricular EF significantly decreased (p less than 0.01) only in patients with previous anterior MI. No correlation has been demonstrated in pre- postoperative changes of the observed parameters, neither between the two groups of previous MI nor between right and left ventricular cavity. Six months after myocardial revascularization, left ventricular performance, as examined with radionuclide angiography, was practically unchanged except for improvement of diastolic function, while right ventricular performance was moderately impaired, more in patients with previous anterior MI than in those with previous inferior MI.

[Radioisotope angiography in the differential diagnosis between aneurysm and pseudoaneurysm of left ventricle. Report of a case]. / L'angiografia radioisotopica nello studio discriminante tra aneurisma e pseudoaneurisma ventricolare sinistro. Descrizione di un caso.

We describe the case of a patient with large posteroinferior left ventricular aneurysm following myocardial infarction. Contrast ventriculography, Doppler echocardiography, as well as radionuclide angiography indicated a small orifice that was in communication with the ventricular cavity. These data suggested the presence of left ventricular pseudoaneurysm. Thus a short-term surgical intervention was performed, but the diagnosis was not confirmed by surgical observation; indeed the presence of a true aneurysm was demonstrated. Our study confirms the diagnostic difficulties by invasive and non invasive techniques in the precise identification of postinfarct pseudoaneurysm. This observation suggests the remarkable interest of our radionuclide ventriculographic results, not usually observed. Thus, we point out the possibilities of several nuclear cardiology imaging in the study of diagnostic problems concerning the analysis of these conditions of myocardial pathology.

[Critical myocardial ischemia in systemic lupus erythematosus. Case report]. / Ischemia miocardica critica in corso di lupus eritematoso sistemico. Descrizione di un caso clinico.

We present the clinical case of a 26-year-old woman, suffering systemic lupus erythematosus for 15 years, who suddenly had coronary heart disease with angina pectoris on mild effort. Thallium 201 exercise test demonstrated clearcut anteroseptal and apical perfusion defects, whereas repeated echocardiography showed a hypokinetic anteroseptal segment; ECG also reported new Q wave in lead V4. After stronger corticosteroid and immunosuppressive treatment, angina pectoris attenuated and perfusion defects disappeared within few months. We hypothesize a coronary artery vasculitis in the course of systemic lupus erythematosus, probably associated with early coronary artery atherosclerosis.

[Urokinase in the therapy of spontaneous angina]. / L'urochinasi nella terapia dell'angina spontanea.

UNLABELLED: In an open non-comparative clinical study, 19 patients with spontaneous angina pectoris admitted to hospital with attacks lasting greater than 10 minutes, unresponsive to nitrate and/or calcium antagonist treatment, at least 2 ECG readings of raised (greater than or equal to 1.5 mm) or lowered (greater than or equal to 1 mm) ST segment not attributable to earlier AMI in the same area, were treated after the interruption of conventional treatment (mean 47 +/- 34.2 min) with 2 million IU endovenous UK in 15 mins followed by 1 million IU endovenous UK in 60 mins. Sixty minutes after UK administration was terminated, they were given a bolus of 5000 IU calcium heparin, followed by 1000 IU per hour for 2 days. Coronary angiography (Judkins technique) was performed before the start of UK treatment and 15, 30, 45, 60 and 75 minutes into it. RESULTS: Basal coronarography showed only "multiple organic stenosis" in 5 out of the 19 patients, a more complex situation suggestive of thrombi in the coronary arteries in 14. Subsequent angiographies (mean 30 mins later) revealed coronarographic improvement in 11 out of the 19 (58%), or 11 out of 14 (78.5%) if we exclude those with simple stenosis. Angina attacks were significantly lower in the 8 days after UK treatment than in the week before it in terms of number (4 v. 1; p less than 0.01), global severity (7 v. 1.5; p less than 0.01) and global duration (45 v. 4.25 min; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

[Mortality of psychiatric patients. A retrospective cohort study of in-patients at the Psychiatric Hospital of Reggio Emilia]. / La mortalità del paziente psichiatrico. Studio di coorte retrospettivo in pazienti lungodegenti nell'Ospedale Psichiatrico di Reggio Emilia.

The authors report the results of historical cohort study in long-term patients of psychiatric hospitals in Reggio Emilia. The cohort was formed by 790 patients hospitalized before 1978, and has been followed-up until 31/12/'89. The results of the study are: 269 subjects deceased (34%); 117 discharges (14.8%) and 411 (52.1%) still in hospital on 1/1/'90. An excess mortality was observed in the cohort. Mortality appears to be particularly high among young patient and females.