Observation of Localized Vibrational Modes of Graphene Nanodomes by Inelastic Atom Scattering.

Inelastic helium atom scattering (HAS) is suitable to determine low-energy (few meV) vibrations spatially localized on structures in the nanometer range. This is illustrated for the nanodomes that appear often on graphene (Gr) epitaxially grown on single crystal metal surfaces. The nature of the inelastic losses observed in Gr/Ru(0001) and Gr/Cu/Ru(0001) has been clarified by intercalation of Cu below the Gr monolayer, which decouples the Gr layer from the Ru substrate and changes substantially the out-of-plane, flexural phonon dispersion of epitaxial Gr, while maintaining the nanodomes and their localized vibrations. He diffraction proves that the Cu-intercalated Gr layer is well ordered structurally, while scanning tunneling microscopy reveals the persistence of the (slightly modified) periodic array of Gr nanodomes. A simple model explains the order of magnitude of the energy losses associated with the Gr nanodomes and their size dependence. The dispersionless, low-energy phonon branches may radically alter the transport of heat in intercalated Gr.

Controlling the spin of co atoms on pt(111) by hydrogen adsorption.

We investigate the effect of H adsorption on the magnetic properties of individual Co atoms on Pt(111) with scanning tunneling microscopy. For pristine Co atoms, we detect no inelastic features in the tunnel spectra. Conversely, CoH and CoH2 show a number of low-energy vibrational features in their differential conductance identified by isotope substitution. Only the fcc-adsorbed species present conductance steps of magnetic origin, with a field splitting identifying their effective spin as Seff=2 for CoH and 3/2 for CoH2. The exposure to H2 and desorption through tunnel electrons allow the reversible control of the spin in half-integer steps. Because of the presence of the surface, the hydrogen-induced spin increase is opposite to the spin sequence of CoHn molecules in the gas phase.

PCR protocol for detection of Vibrio ordalii by amplification of the vohB (hemolysin) gene.

Vibrio ordalii is the causative agent of atypical vibriosis and has the potential to cause severe losses in salmonid aquaculture. To prevent and control outbreaks, a rapid, reproducible, sensitive, and effective diagnostic method is needed. We evaluated a new conventional polymerase chain reaction (PCR) and real-time PCR (qPCR) protocol using a primer set (VohB_Fw-VohB_Rv) designed to amplify a 112 bp fragment flanking the vohB gene (coding for hemolysin production), against 24 V. ordalii strains isolated from different fish species, the V. ordalii type strain, and 42 representative related and unrelated bacterial species. The primer set was species-specific, recognizing all V. ordalii strains evaluated, with no cross-reaction with the other bacterial species. A sensitivity of 103 copies of the vohB gene was obtained with a standard curve. When the VohB_Fw-VohB_Rv qPCR protocol was applied to Atlantic salmon seeded tissues (kidney, liver, spleen, and muscle), the detection limit ranged from 5.27 × 102 to 4.13 × 103 V. ordalii CFU ml-1, i.e. 62 to 145 copies of the vohB gene, using the previously calculated standard curve. The conventional PCR also detected V. ordalii, but the total reaction time was 1 h longer. When the qPCR protocol was applied to naturally infected cage-cultured Atlantic salmon samples, 5 of 8 fish tested positive for V. ordalii, but only one of them was diagnosed as positive by direct cultivation on agar. We conclude that the PCR protocol evaluated is fast, specific, and sensitive enough to detect V. ordalii in infected tissues and is an important tool for secure diagnosis of atypical vibriosis, and is therefore helpful for the control of the disease through the prompt detection within fish populations.

Magnetic moment and anisotropy of individual Co atoms on graphene.

We report on the magnetic properties of single Co atoms on graphene on Pt(111). By means of scanning tunneling microscopy spin-excitation spectroscopy, we infer a magnetic anisotropy of K=-8.1 meV with out-of-plane hard axis and a magnetic moment of 2.2µ(B). Co adsorbs on the sixfold graphene hollow site. Upon hydrogen adsorption, three differently hydrogenated species are identified. Their magnetic properties are very different from those of clean Co. Ab initio calculations support our results and reveal that the large magnetic anisotropy stems from strong ligand field effects due to the interaction between Co and graphene orbitals.

Reactivity of periodically rippled graphene grown on Ru(0001).

We report here the reactivity of epitaxial graphene islands and complete monolayers on Ru(0001) towards molecular oxygen and air. The graphene is prepared by thermal decomposition of ethylene molecules pre-adsorbed on an Ru(0001) surface in an ultra-high vacuum chamber. The graphene layer presents a periodically rippled structure that is dictated by the misfit between graphene and Ru(0001) lattice parameters. The periodic ripples produce spatial charge redistribution in the graphene and modifies its electronic structure around the Fermi level. In order to investigate the reactivity of graphene we expose graphene islands to a partial pressure of oxygen and following the evolution of the surface by STM during the exposure. For the exposure to air we removed the sample from the UHV chamber and we re-introduce it after several hours, taking STM images before and after. The surface areas not covered by the graphene islands present a dramatic change but the graphene structure, even the borders of the islands, remain intact. In the case of a complete graphene monolayer the exposure to oxygen or to air does not affect or destroy the rippled structure of the graphene monolayer.

The role of the amorphous phase in the re-crystallization process of cold-crystallized poly(ethylene terephthalate).

The process of re-crystallization in poly(ethylene terephthalate) is studied by means of X-ray diffraction (SAXS and WAXS) and dynamical mechanical thermal analysis. Samples cold-crystallized for 9h at the temperatures T(c) = 100°C and T (c) = 160°C, i.e. in the middle of the alpha relaxation region and close to its upper bound, respectively, are analyzed. During heating from room temperature, a structural rearrangement of the stacks is always found at T (r) approximately T (c) + 20°C. This process is characterized by a decrease of the linear crystallinity, irrespective of T(c); on the other hand, the WAXS crystallinity never increases with T below T(c+30)°C. The lamellar thickness in the low-T(c) sample decreases significantly after the structural transition, whereas in the high-T(c) sample the lamellar thickness remains almost unchanged. In both, high- and low-T(c), the interlamellar thickness increases above T(r). Moreover, the high-T(c) sample shows a lower rate of decrease of the mechanical performance with increasing T as the threshold T(r) is crossed. This result is interpreted in terms of the formation of rigid amorphous domains where the chains are partially oriented. The presence of these domains would determine i) the stabilization of the crystalline lamellae from the thermodynamic point of view and ii) the increase of the elastic modulus of the amorphous interlamellar regions. This idea is discussed by resorting to a phase diagram. An estimation of the chemical-potential increase of the interlamellar amorphous regions, due to the enhancement of the structural constraints hindering segmental mobility, is offered. Finally, previous calculations developed within the framework of the Gaussian chain model (F.J. Baltá Calleja et al., Phys. Rev. B 75, 224201 (2007)) are used here to estimate the degree of chain orientation induced by the structural transition of the stacks.

Graphene catalyzes the reversible formation of a C-C bond between two molecules.

Carbon deposits are well-known inhibitors of transition metal catalysts. In contrast to this undesirable behavior, here we show that epitaxial graphene grown on Ru(0001) promotes the reversible formation of a C-C bond between -CH2CN and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ). The catalytic role of graphene is multifaceted: First, it allows for an efficient charge transfer between the surface and the reactants, thus favoring changes in carbon hybridization; second, it holds the reactants in place and makes them reactive. The reaction is fully reversible by injecting electrons with an STM tip on the empty molecular orbitals of the product. The making and breaking of the C-C bond is accompanied by the switching off and on of a Kondo resonance, so that the system can be viewed as a reversible magnetic switch controlled by a chemical reaction.

Early open mitral commissurotomy: long-term results.

It has frequently been suggested that early mitral commissurotomy could improve long-term results in patients with severe mitral stenosis. However, the real advantages of this procedure have yet to be demonstrated. To evaluate this hypothesis, we retrospectively studied 397 patients who underwent operation for mitral stenosis in our unit between 1978 and 1988. Forty of these patients (group I) fulfilled the criteria for early mitral commissurotomy: being young (average age 33 years), being asymptomatic or showing few symptoms, and being in sinus rhythm. The remaining 357 patients who underwent operation during the same period of time served as control (group II). Mitral valve replacement (p < 0.05) and associated tricuspid annuloplasty (p < 0.05) occurred less frequently in patients from group I than it did in patients from group II. Survival after 11 years for patients with early mitral commissurotomy was 100%, 90% of whom were in functional class I, were in sinus rhythm, and were receiving no medication whatsoever. Ninety-six percent of these patients were free of complications after 11 years, compared with 73% of patients in group II (p < 0.05). In our opinion, these results support the use of early mitral commissurotomy for young patients in sinus rhythm, who are symptom free, who are and who have a mitral valve area is 1.3 cm2 or less.

A comparison of repair and replacement for mitral stenosis with partially calcified valve.

From January 1978 to December 1987 we operated on 135 patients with calcified mitral stenosis. In 60 patients a conservative operation was performed (group I). Nine patients required mitral annuloplasty associated with the commissurotomy. The other 75 patients underwent mitral valve replacement (group II). In 37 patients a mechanical prosthesis was used and in 38 a biologic one. The patients given mitral valve replacement had a more heavily calcified valve than those undergoing a conservative procedure. Twenty-one patients (12 from group I and 13 from group II) required associated tricuspid annuloplasty. The mean follow-up time was 69.1 months (1 months to 10 years). There were no significant differences between the two groups in terms of operative death (0% and 4%, respectively), postoperative functional class, actuarial survival rate at 10 years (84% and 96%, respectively), and probability of freedom from thromboemboli at 10 years (98% and 96%, respectively). However, the probability of freedom from reoperation at 10 years significantly favored the conservative surgery group (84% and 69%, respectively, p less than 0.01). Finally, the probability of freedom from complications at 10 years was also significantly higher in the conservative surgery group (82% and 64%, respectively, p less than 0.005). Because of these results we believe that conservative surgery is, at present, a better alternative than mitral valve replacement for patients with partially calcified mitral stenosis.

Preliminary experience with deflazacort, a new synthetic steroid with fewer undesirable side effects, in heart transplant patients.

Prednisone is widely used by most heart transplant units, despite its frequent side effects. Deflazacort, a new oral synthetic steroid with fewer side effects, has not been studied in heart transplant patients. Our initial experience with 26 heart transplant patients in whom prednisone was replaced by deflazacort at 11 +/- 11 months after transplantation is reported. After the switch to deflazacort, a significant decreased was noted in glycemia, total cholesterol, and LDL-cholesterol (p < 0.001). No difference was noted in severity or frequency of rejection and infection between patients being treated with deflazacort and another 26 patients who continued to be treated with prednisone over a comparable period of time after transplantation.

Pacing requirements after orthotopic heart transplantation: incidence and related factors.

To assess the incidence of severe bradyarrhythmia and pacing requirements after orthotopic heart transplantation, as well as the possible causal mechanisms, we have reviewed our experience on 52 consecutive transplant patients. The overall incidence of bradyarrhythmia requiring pacing for at least 24 hours after transplantation was 27% (14 patients). The conditions of three of them required pacing for less than 1 week; the conditions of the other 11 patients (21%) required pacing for more than 1 week. Normal sinus rhythm resumed in all but four patients within 3 weeks; a permanent pacemaker was implanted in these four patients (7.6% of all 52 patients and 28% of patients requiring temporary pacing). Late complete heart block associated with acute rejection developed in two patients whose conditions required implantation of a permanent pacemaker. The age and sex of the recipient and donor were similar for patients with or without bradyarrhythmia. The percentage of patients with or without bradyarrhythmias taking amiodarone before transplantation (57% and 46%, respectively), total ischemic time (133 +/- 33 and 123 +/- 37 minutes, respectively), and cardiopulmonary bypass time (117 +/- 17 and 132 +/- 65 minutes, respectively) were not significantly different for either group of patients. The initial temperature of cardioplegic solution for organ storage and the preimplantation myocardial temperature were, however, significantly lower in patients whose conditions required pacing immediately after transplantation than in those whose conditions did not require pacing (5.3 +/- 1.7 degrees C versus 6.5 +/- 1.5 degrees C, p less than 0.05, and 3.9 +/- 1.6 degrees C versus 5.7 +/- 2.6 degrees C, p less than 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Induced mutagenic effects in the nucleotide excision repair deficient Drosophila mutant mus201(D1), expressing a truncated XPG protein.

Defects in nucleotide excision repair (NER) as defined by the UV sensitivity of xeroderma pigmentosum (XP), Cockayne syndrome (CS) and trichothiodystrophy (TTD) patients has lead to the identification of most of the genes involved: XPA through XPG, CSA and CSB. Whereas XP patients often show an increased risk for skin cancer after exposure to sunlight, this is not the case for patients with CS and TTD. Several CS patients have been shown to carry a defect in the XPG gene. The XPG, a structure specific endonuclease makes the incision 3' of damage and is also involved in the subsequent 5'incision during the NER process. In addition, XPG plays a role in the removal of oxidative DNA damage. The Drosophila XPG gene was isolated and based on the molecular defect of a spontaneous (insertion) and an EMS induced mutant, it was shown that a mutated XPG is responsible for the Drosophila mutagen-sensitive mutants mus201. One of these mutants, mus201(D1) has been used extensively in studies of the effects and mechanisms of many chemical mutagens as well as X-rays. The results of these studies are discussed in the light of the finding that mus201p is the Drosophila homologue of XPG.

Modulation of the toxic and mutagenic effects induced by methyl methanesulfonate in Chinese hamster ovary cells by overexpression of the rat N-alkylpurine-DNA glycosylase.

Exposure of mammalian cells to alkylating agents causes transfer of alkyl groups to N- as well as O-atoms of DNA bases. Especially the O-alkylated G and T bases have strong mutagenic properties, since they are capable of mispairing during replication. The mutagenic potential of N-alkylbases is less clear although specific base excision repair (BER) pathways exist which remove those lesions from the DNA. We investigated the relative contribution of N-alkylations to mutation induction at the Hprt gene in cultured Chinese hamster ovary cells (CHO). To this end BER activity in CHO cells was modulated by introduction of an expression vector carrying the rat N-alkylpurine-DNA glycosylase (APDG) gene, which codes for a glycosylase that is able to remove 3-methyladenine and 7-methylguanine from DNA thereby generating apurinic sites. Upon selection of a CHO clone which 10 times overproduced APDG compared to control CHO cells, mutation induction, the mutational spectrum, and cell survival were determined in both cell lines following treatment with methyl methanesulfonate (MMS). The results show that over-expression of APDG renders CHO cells more sensitive for mutation induction as well as cytotoxicity induced by MMS. The involvement of apurinic sites in induction of base pair changes at positions where 3-methyladenine was induced is inferred from the observation that the mutational spectrum of MMS-induced mutations in APDG-CHO cells showed twice as much base pair changes at AT base pairs (33.3%) compared to the spectrum of MMS-induced mutations in CHO-control cells (15.8%).

Aberrant right subclavian artery associated with common carotid trunk. A rare cause of vascular ring.

We have reviewed four cases of incomplete vascular rings caused by the presence of a common carotid trunk from which arose both carotid arteries associated with an aberrant right subclavian artery. The patients were aged between 3 and 9 months. All patients presented with recurrent respiratory tract infections. Three patients showed signs of malnutrition and failure to thrive caused by episodes of bronchial aspiration from extrinsic compression of the oesophagus. One patient presented with dyspnoea induced by feeding and another had stridor. A common carotid trunk associated with an aberrant subclavian artery was confirmed in all cases. No other associated anomaly was observed in any patient. Ligature and section of the anomalous right subclavian artery was performed in all patients. The low incidence of this type of vascular ring, its physiopathological mechanism and surgical management are discussed.

Mitral valve surgery through right thoracotomy.

UNLABELLED: Two years ago we had, for technical reason to resuscitate right thoracotomy (RT) to approach the mitral valve. Since then we have used it in 23 patients. 18 of them had had at least one operation through a medium sternotomy. In 5 cases the right approach was electively used, as first choice to repair or replace the mitral valve. Intracardiac surgery was performed routinely with moderate hypothermia and controlled ventricular fibrillation with the aorta unclamped. Only in one case, an unexpected aortic incompetence forced us to cross-clamp the aorta and replace the valve using crystalloid cold cardioplegia. 14 patients underwent mitral valve replacement. In 5 cases a leaking mitral prosthesis was successfully reattached and in 4 cases the native valve was repaired. 2 patients died (9%) for reasons unrelated to the technique. We did not have any case of air embolism. CONCLUSION: 1) RT is very useful to approach the mitral valve, specially in patients who previously had: a) several sternotomies, b) postoperative mediastinitis, specially if treated by omentoplasty, c) coronary artery bypass; 2) the good view to the mitral valve obtained with the aorta unclamped, make us think if the mitral repair should elective done through this approach.

Pulmonary valve endocarditis during puerperal sepsis.

A case of pulmonary valve endocarditis caused by Staphylococcus aureus during puerperal sepsis in a female patient is reported. The M-mode and two dimensional echocardiographic finding are described. A review of the literature shows that this entity is rare. A large vegetation in the leaflet of the pulmonary valve was excised and the patient recovered after a full course of antibiotics.

Post-coronariography dissection of the right coronary artery.

The case of a patient undergoing an emergency aortocoronary bypass to the right coronary artery after its acute dissection at coronariography is presented. Surgery was carried out two hours after the incident. After successful recovery and postoperative study, it was concluded that the main technical problem posed by this operation which was whether or not to ligate proximally the right coronary was satisfactorily solved by the initial decision not to ligate it.

Comparative evaluation of pentoxifylline, buflomedil, and nifedipine in the treatment of intermittent claudication of the lower limbs.

In the light of the current controversy surrounding the use of hemorheologic and vasodilator drugs in the treatment of peripheral arteriosclerosis, a comparative study was designed in order to evaluate the efficacy of pentoxifylline, buflomedil, and nifedipine in 45 patients with peripheral arterial disease (Fontaine stage II). The patients in this prospective randomized study were divided into three groups: 15 patients received pentoxifylline treatment (1,200 mg/day), 15 were treated with buflomedil (600 mg/day), and 15 with nifedipine (60 mg/day). Response to treatment was assessed at the start of the study and after forty-five and ninety days, by clinical examination, Doppler test, strain test, and digital occlusion plethysmography using a strain gauge ring. Pentoxifylline was significantly more effective (P < 0.05) than buflomedil and nifedipine at ninety days in improving walking performance, resting toe pressure, resting and postexercise ankle/brachial pressure ratio, and basal/postischemic toe-pulse ratio. Significant differences within groups were also noted for initial claudication, toe peak-flow time, pulse reappearance time (PRT/2), and maximum postischemic flow time, together with significant intergroup variables. In conclusion, pentoxifylline proved more effective than the other drugs tested in: 1. improving distal pressure and resting microcirculatory blood flow; 2. increasing postexercise distal flow, ratios, and pressures and enabling faster recuperation of basal pulse rates; 3. increasing initial claudication distance in the strain test within the test group and achieving a greater absolute subjective claudication distance than that obtained using the other treatments.

[Orthotopic heart transplant. Study of early morbimortality (< or = 30 days). Experience at the Reina Sofía Hospital (Córdoba)]. / Transplante cardíaco ortotópico. Estudio de la morbimortalidad precoz (< ó = 30 días). Experiencia del Hospital Reina Sofía (Córdoba).

From may 1986 to december 1991, we have performed 90 heart transplantation in the Hospital "Reina Sofía" from Córdoba. In the present study we analyze the early morbidity and mortality in a retrospective study on complications and factors determining its incidence. Seventy patients were male (86%) and 13 female (14%). Age ranged from 12 and 65 years. The 31% of patients needed in pharmacological support before transplantation, 15 of them were operated in a emergency situation because of cardiogenic shock. The pulmonary resistances oscillated between 0.5 and 8.7 units/m2 (Wood) (mean 2.5 +/- 1.4 units/m2). The mean time of ischaemia was 136 +/- 38 minutes (range 5-255 min). Hospital mortality (< or = 30 days) was 8.8% (8/90). No predictive factors from donor and recipient were found. Three main influences on complications were analyzed: a) influence of myocardial temperature, b) role of hematic cardioplegia, and c) usefulness of Aprotinin. Eighteen patients (20%) developed severe bradyarrhythmia needing a pacemaker in the post-operative period. We found a significant relationship with myocardial temperature (4.3 +/- 2.1 vs 6.2 +/- 2.6; p < 0.05) and transport solution temperature (5.8 +/- 2.3 vs 7.3 +/- 1.9; p < 0.05). No significant influence was found on the time of ischaemia, previous heart disease, previous treatment with Amiodarona, clinical condition, etc.(ABSTRACT TRUNCATED AT 250 WORDS)

[Myocardial revascularization and complete correction of tetralogy of Fallot in an adult. A case report]. / Revascularización miocárdica y corrección completa de la tetralogía de Fallot en el adulto. Presentación de un caso.

The case is reported of a 62 year-old male having a clinical history of grade II dyspnoea from 9 year ago and recently showing grade II angina. He had presented mild cyanosis. Suspecting the existence of coronary arteriosclerosis, and with the clinical diagnosis of tetralogy of Fallot based particularly on two-dimensional and M-mode echocardiography, and angio-hemodynamic study was made which confirmed the presence of congenital heart disease and also revealed significant coronary lesions of the circumflex and right coronary arteries. The patient underwent surgery which involved complete correction of the tetralogy of Fallot and the placing of two aortocoronary grafts onto the circumflex and right coronary arteries. Favorable progress was noted both immediately after operation and 6 months later. Although cases have been described of Fallot disease associated with acute myocardial infarction, we believe that this is the first time a patient has undergone myocardial revascularization at the same time as undergoing complete correction of the congenital heart disease.