Vascular reactivity stimulated by TMA and TMAO: Are perivascular adipose tissue and endothelium involved?

Trimethylamine (TMA), formed by intestinal microbiota, and its Flavin-Monooxygenase 3 (FMO3) product Trimethylamine-N-Oxide (TMAO), are potential modulators of host cardiometabolic phenotypes. High circulating levels of TMAO are associated with increased risk for cardiovascular diseases. We hypothesized that TMA/TMAO could directly change the vascular tone. Perivascular adipose tissue (PVAT) helps to regulate vascular homeostasis and may also possess FMO3. Thoracic aorta with(+) or without(-) PVAT, also + or - the endothelium (E), of male Sprague Dawley rats were isolated for measurement of isometric tone in response to TMA/TMAO (1nM-0.5 M). Immunohistochemistry (IHC) studies were done to identify the presence of FMO3. TMA and TMAO elicited concentration-dependent arterial contraction. However, at a maximally achievable concentration (0.2 M), contraction stimulated by TMA was of a greater magnitude (141.5 ± 16% of maximum phenylephrine contraction) than that elicited by TMAO (19.1 ± 4.03%) with PVAT and endothelium intact. When PVAT was preserved, TMAO-induced contraction was extensively reduced the presence (19.1 ± 4.03%) versus absence of E (147.2 ± 20.5%), indicating that the endothelium plays a protective role against TMAO-induced contraction. FMO3 enzyme was present in aortic PVAT, but the FMO3 inhibitor methimazole did not affect contraction stimulated by TMA in aorta + PVAT. However, the l-type calcium channel blocker nifedipine reduced TMA-induced contraction by ∼50% compared to the vehicle. Though a high concentration of these compounds was needed to achieve contraction, the findings that TMA-induced contraction was independent of PVAT and E and mediated by nifedipine-sensitive calcium channels suggest metabolite-induced contraction may be physiologically important.

Renal perivascular adipose tissue: Form and function.

Renal sympathetic activity affects blood pressure in part by increasing renovascular resistance via release of norepinephrine (NE) from sympathetic nerves onto renal arteries. Here we test the idea that adipose tissue adjacent to renal blood vessels, i.e. renal perivascular adipose tissue (RPVAT), contains a pool of NE which can be released to alter renal vascular function. RPVAT was obtained from around the main renal artery/vein of the male Sprague Dawley rats. Thoracic aortic PVAT and mesenteric PVAT also were studied as brown-like and white fat comparators respectively. RPVAT was identified as a mix of white and brown adipocytes, because of expression of both brown-like (e.g. uncoupling protein 1) and white adipogenic genes. All PVATs contained NE (ng/g tissue, RPVAT:524 ±â€¯68, TAPVAT:740 ±â€¯16, MPVAT:96 ±â€¯24). NE was visualized specifically in RPVAT adipocytes by immunohistochemistry. The presence of RPVAT (+RPVAT) did not alter the response of isolated renal arteries to NE compared to responses of arteries without RPVAT (-RPVAT). By contrast, the maximum contraction to the sympathomimetic tyramine was ~2× greater in the renal artery +PVAT versus -PVAT. Tyramine-induced contraction in +RPVAT renal arteries was reduced by the α1-adrenoceptor antagonist prazosin and the NE transporter inhibitor nisoxetine. These results suggest that tyramine caused release of NE from RPVAT. Renal denervation significantly (>50%) reduced NE content of RPVAT but did not modify tyramine-induced contraction of +RPVAT renal arteries. Collectively, these data support the existence of a releasable pool of NE in RPVAT that is independent of renal sympathetic innervation and has the potential to change renal arterial function.

Hydrocarbon decomposition kinetics on the Ir(111) surface.

The kinetics of the thermal decomposition of hydrocarbons on the Ir(111) surface is determined using kinetic Monte Carlo (kMC) and rate equations simulations, both based on the density functional theory (DFT) calculated energy barriers of the involved reaction processes. This decomposition process is important for understanding the early stages of epitaxial graphene growth where the deposited hydrocarbon acts as a carbon feedstock for graphene formation. The methodology of the kMC simulations and the rate equation approaches is discussed and a comparison between the results obtained from both approaches is made in the case of the temperature programmed decomposition of ethylene for different initial coverages. The theoretical results are verified against experimental data from in situ X-ray photoelectron spectroscopy (XPS) experiments. Both theoretical approaches give reasonable results; however we find that, as expected, rate equations are less reliable at high coverages. We find that the agreement between experiment and theory can be improved in all cases if slight adjustments are made to the energy barriers in order to account for the intrinsic errors in DFT. Finally we extend our approach to the case where hydrocarbon species are dosed onto the substrate continuously, as in the chemical vapour deposition (CVD) graphene growth method. For ethylene and methane the thermal decomposition mechanism is determined, and it is found that in both cases the formation of C monomers is to be expected, which is limited by the presence of hydrogen atoms.

Carlos Chagas Discoveries as a Drop Back to Scientific Construction of Chronic Chagas Heart Disease / Descobertas de Carlos Chagas como Pano de Fundo para a Construção Científica da Cardiopatia Chagásica Crônica

Abstract The scientific construction of chronic Chagas heart disease (CCHD) started in 1910 when Carlos Chagas highlighted the presence of cardiac arrhythmia during physical examination of patients with chronic Chagas disease, and described a case of heart failure associated with myocardial inflammation and nests of parasites at autopsy. He described sudden cardiac death associated with arrhythmias in 1911, and its association with complete AV block detected by Jacquet's polygraph as Chagas reported in 1912. Chagas showed the presence of myocardial fibrosis underlying the clinical picture of CCHD in 1916, he presented a full characterization of the clinical aspects of CCHD in 1922. In 1928, Chagas detected fibrosis of the conductive system, and pointed out the presence of marked cardiomegaly at the chest X-Ray associated with minimal symptomatology. The use of serological reaction to diagnose CCHD was put into clinical practice in 1936, after Chagas' death, which along with the 12-lead ECG, revealed the epidemiological importance of CCHD in 1945. In 1953, the long period between initial infection and appearance of CCHD was established, whereas the annual incidence of CCHD from patients with the indeterminate form of the disease was established in 1956. The use of heart catheterization in 1965, exercise stress testing in 1973, Holter monitoring in 1975, Electrophysiologic testing in 1973, echocardiography in 1975, endomyocardial biopsy in 1981, and Magnetic Resonance Imaging in 1995, added to the fundamental clinical aspects of CCHD as described by Carlos Chagas.

Resumo A construção científica da doença de Chagas crônica (DCC) começou em 1910, quando Carlos Chagas salientou a presença de arritmia cardíaca em exames físicos de pacientes com doença de Chagas crônica, e descreveu um caso de insuficiência cardíaca associada à inflamação do miocárdio e à presença de ninhos de parasitas durante a autópsia. Ele descreveu morte súbita cardíaca associada a arritmias em 1911, e sua associação ao bloqueio AV total detectado com o polígrafo de Jacquet, conforme reportou em 1912. Chagas mostrou a presença de fibrose do miocárdio como subjacente ao quadro clínico da DCC em 1916, e apresentou uma caracterização completa dos aspectos clínicos da DCC em 1922. Em 1928, Chagas detectou fibrose do sistema condutor, e apontou a presença de cardiomegalia acentuada no raio X do tórax, associada a sintomatologia mínima. O uso da reação sorológica no diagnóstico de DCC foi posta em prática clínica em 1936, após a morte de Chagas, e juntamente com o ECG de 12 derivações, revelou a importância epidemiológica da DCC em 1945. Em 1953, ficou comprovado o longo período de tempo entre a infecção inicial e o aparecimento de DCC, enquanto que a incidência anual de DCC na forma indeterminada da doença foi estabelecida em 1956. Os aspectos clínicos fundamentais de DCC descritos por Carlos Chagas foram complementados pelo uso de cateterismo cardíaco em 1965, teste ergométrico em 1973, Holter em 1973, teste eletrofisiológico em 1975, ecocardiografia em 1975, biópsia endomiocárdica em 1981 e ressonância magnética em 1995.

Carlos Chagas Discoveries as a Drop Back to Scientific Construction of Chronic Chagas Heart Disease.

The scientific construction of chronic Chagas heart disease (CCHD) started in 1910 when Carlos Chagas highlighted the presence of cardiac arrhythmia during physical examination of patients with chronic Chagas disease, and described a case of heart failure associated with myocardial inflammation and nests of parasites at autopsy. He described sudden cardiac death associated with arrhythmias in 1911, and its association with complete AV block detected by Jacquet's polygraph as Chagas reported in 1912. Chagas showed the presence of myocardial fibrosis underlying the clinical picture of CCHD in 1916, he presented a full characterization of the clinical aspects of CCHD in 1922. In 1928, Chagas detected fibrosis of the conductive system, and pointed out the presence of marked cardiomegaly at the chest X-Ray associated with minimal symptomatology. The use of serological reaction to diagnose CCHD was put into clinical practice in 1936, after Chagas' death, which along with the 12-lead ECG, revealed the epidemiological importance of CCHD in 1945. In 1953, the long period between initial infection and appearance of CCHD was established, whereas the annual incidence of CCHD from patients with the indeterminate form of the disease was established in 1956. The use of heart catheterization in 1965, exercise stress testing in 1973, Holter monitoring in 1975, Electrophysiologic testing in 1973, echocardiography in 1975, endomyocardial biopsy in 1981, and Magnetic Resonance Imaging in 1995, added to the fundamental clinical aspects of CCHD as described by Carlos Chagas.

Theoretical and experimental investigation of optical absorption anisotropy in ß-Ga2O3.

The question of optical bandgap anisotropy in the monoclinic semiconductor ß-Ga2O3 was revisited by combining accurate optical absorption measurements with theoretical analysis, performed using different advanced computation methods. As expected, the bandgap edge of bulk ß-Ga2O3 was found to be a function of light polarization and crystal orientation, with the lowest onset occurring at polarization in the ac crystal plane around 4.5-4.6 eV; polarization along b unambiguously shifts the onset up by 0.2 eV. The theoretical analysis clearly indicates that the shift in the b onset is due to a suppression of the transition matrix elements of the three top valence bands at Γ point.

Interplay between electronic and structural properties in the Pb/Ag(1 0 0) interface.

We report an investigation of the structural and electronic properties of a Pb monolayer (ML) grown on Ag(1 0 0), by combining x-ray photoelectron diffraction (XPD) and angle resolved photoelectron spectroscopy (ARPES). The Pb atoms are found to arrange in a pseudo-hexagonal adlayer commensurate to the underlying square Ag substrate, resulting in a coincidence cell with c([Formula: see text]) periodicity. The electronic structure of the Pb ML in proximity of the Fermi level consists in three p-derived bands, which show different degrees of hybridization with the substrate for their different orbital characters. In particular, we report that the p xy states disperse without forming energy gap, in contrast to previous ARPES studies of the Pb ML on different metallic substrates. We attribute the absence of energy gap to the commensurability between substrate and adlayer, resulting in a higher two-dimensionality of the Pb ML.

Human nail plate modifications induced by onychomycosis: implications for topical therapy.

PURPOSE: Through the characterisation of the human onchomycotic nail plate this study aimed to inform the design of new topical ungual formulations. METHODS: The mechanical properties of the human nail were characterised using a Lloyd tensile strength tester. The nail's density was determined via pycnometry and the nail's ultrastructure by electron microscopy. Raman spectroscopy analysed the keratin disulphide bonds within the nail and its permeability properties were assessed by quantifying water and rhodamine uptake. RESULTS: Chronic in vivo nail plate infection increased human nailplate thickness (healthy 0.49 ± 0.15 mm; diseased 1.20 ± 0.67 mm), but reduced its tensile strength (healthy 63.7 ± 13.4 MPa; diseased 41.7 ± 5.0 MPa) and density (healthy 1.34 ± 0.01 g/cm(3); diseased 1.29 ± 0.00 g/cm(3)). Onchomycosis caused cell-cell separation, without disrupting the nail disulfide bonds or desmosomes. The diseased and healthy nails showed equivalent water uptake profiles, but the rhodamine penetration was 4-fold higher in the diseased nails using a PBS vehicle and 3 -fold higher in an ethanol/PBS vehicle. CONCLUSIONS: Onchomycotic nails presented a thicker but more porous barrier, and its eroded intracellular matrix rendered the tissue more permeable to topically applied chemicals when an aqueous vehicle was used.

Development of Anatomophysiologic Knowledge Regarding the Cardiovascular System: From Egyptians to Harvey / Evolução do Conhecimento Anatomofisiológico do Sistema Cardiovascular: dos Egípcios a Harvey

Our knowledge regarding the anatomophysiology of the cardiovascular system (CVS) has progressed since the fourth millennium BC. In Egypt (3500 BC), it was believed that a set of channels are interconnected to the heart, transporting air, urine, air, blood, and the soul. One thousand years later, the heart was established as the center of the CVS by the Hippocratic Corpus in the medical school of Kos, and some of the CVS anatomical characteristics were defined. The CVS was known to transport blood via the right ventricle through veins and the pneuma via the left ventricle through arteries. Two hundred years later, in Alexandria, following the development of human anatomical dissection, Herophilus discovered that arteries were 6 times thicker than veins, and Erasistratus described the semilunar valves, emphasizing that arteries were filled with blood when ventricles were empty. Further, 200 years later, Galen demonstrated that arteries contained blood and not air. With the decline of the Roman Empire, Greco-Roman medical knowledge about the CVS was preserved in Persia, and later in Islam where, Ibn Nafis inaccurately described pulmonary circulation. The resurgence of dissection of the human body in Europe in the 14th century was associated with the revival of the knowledge pertaining to the CVS. The main findings were the description of pulmonary circulation by Servetus, the anatomical discoveries of Vesalius, the demonstration of pulmonary circulation by Colombo, and the discovery of valves in veins by Fabricius. Following these developments, Harvey described blood circulation.

O conhecimento da anatomofisiologia do Sistema Cardiovascular (SCV) progride desde o quarto milênio AC. No Egito (3500 AC), acreditava-se que um conjunto de canais conectava-se ao coração, transportando ar, urina, ar, sangue e a alma. Mil anos após, o Corpo Hipocrático, na escola médica de Kós, estabeleceu o coração como o centro do SCV, definindo algumas características deste órgão. O SCV transportava sangue via ventrículo direito pelas veias, e o pneuma via ventrículo esquerdo pelas artérias. Duzentos anos depois, em Alexandria, com o aparecimento da dissecção anatômica do corpo humano, Herophilus descobriu que as artérias eram seis vezes mais espessas que as veias, enquanto que Erasistratus descreveu as válvulas semilunares, enfatizando que as artérias eram preenchidas por sangue quando o ventrículo esquerdo se esvaziava. Duzentos anos depois, Galeno demonstrou que as artérias continham sangue, não ar. Com o declínio do Império Romano, todo o conhecimento médico Greco-romano do SCV foi preservado na Pérsia, e posteriormente no Islã, onde Ibn-Nafis descreveu incompletamente a circulação pulmonar. Aqui, deve-se enfatizar a incompleta descrição da circulação pulmonar por Ibn-Nafis. A ressurgência da dissecção do corpo humano na Europa no século XIV é associada ao renascimento do conhecimento do SCV. Os principais marcos foram a descrição da circulação pulmonar por Servetus, as descobertas anatômicas de Vesalius, a demonstração da circulação pulmonar por Colombo, e a descoberta das válvulas das veias por Fabricius. Tal contexto abriu o caminho para Harvey descobrir a circulação do sangue.

Precordial chest pain in patients with chronic Chagas disease.

Precordial chest pain affects about 15% to 33% of patients with chronic Chagas disease. In the absence of megaesophagus, it should be ascribed to chronic Chagas heart disease. Precordial chest pain is atypical because it can usually neither be associated to physical exercise nor be alleviated by nitroglycerin. However, in certain circumstances, precordial chest pain can masquerade as acute coronary syndrome. Although obstructive coronary artery disease can occasionally be found, microvascular angina seems to be the mechanism behind such phenomenon. Precordial chest pain not always has a benign clinical course; sometimes, it can herald a dismal prognosis. On the basis of cases previously reported, it seems that nitrates, betablockers and/or calcium channel blockers can be of value in the treatment of this condition.

Contextual considerations in implementing problem-based learning approaches in a Brazilian medical curriculum: the UNAERP experience.

BACKGROUND: Despite being a well-established pedagogical approach in medical education, the implementation of problem-based learning (PBL) approaches hinges not only on educational aspects of the medical curriculum but also on the characteristics and necessities of the health system and the medical labor market within which it is situated. AIM: To report our experiences implementing a PBL-based approach in a region of Brazil where: 1) all pre-university education and the vast majority of medical courses are based on traditional, lecture-based instructions; and 2) students' career interests in primary care, arguably the prototypical PBL trainee, are heavily disfavored because of economics. RESULTS: Brazilian guidelines require that clinical training take place during the last 2 years of the medical program and include intensive, supervised, inpatient and outpatient rotations in pediatrics, family medicine, obstetrics and gynecology, internal medicine, and surgery. Throughout the pre-clinical curriculum, then, students learn to deal with progressively more difficult and complex cases--typically through the use of PBL tutors in a primary care context. However, because of curricular time constraints in the clerkships, and students' general preoccupation with specialty practice, the continuation of PBL-based approaches in the pre-clinical years--and the expansion of PBL into the clerkships--has become exceedingly difficult. DISCUSSION AND CONCLUSION: Our experience illustrates the importance of context (both cultural and structural) in implementing certain pedagogies within one Brazilian training program. We plan to address these barriers by: 1) integrating units, whenever possible, within a spiral curriculum; 2) introducing real patients earlier in students' pre-clinical coursework (primarily in a primary care setting); and 3) using subject experts as PBL tutors to better motivate students.

Development of anatomophysiologic knowledge regarding the cardiovascular system: from Egyptians to Harvey.

Our knowledge regarding the anatomophysiology of the cardiovascular system (CVS) has progressed since the fourth millennium BC. In Egypt (3500 BC), it was believed that a set of channels are interconnected to the heart, transporting air, urine, air, blood, and the soul. One thousand years later, the heart was established as the center of the CVS by the Hippocratic Corpus in the medical school of Kos, and some of the CVS anatomical characteristics were defined. The CVS was known to transport blood via the right ventricle through veins and the pneuma via the left ventricle through arteries. Two hundred years later, in Alexandria, following the development of human anatomical dissection, Herophilus discovered that arteries were 6 times thicker than veins, and Erasistratus described the semilunar valves, emphasizing that arteries were filled with blood when ventricles were empty. Further, 200 years later, Galen demonstrated that arteries contained blood and not air. With the decline of the Roman Empire, Greco-Roman medical knowledge about the CVS was preserved in Persia, and later in Islam where, Ibn Nafis inaccurately described pulmonary circulation. The resurgence of dissection of the human body in Europe in the 14th century was associated with the revival of the knowledge pertaining to the CVS. The main findings were the description of pulmonary circulation by Servetus, the anatomical discoveries of Vesalius, the demonstration of pulmonary circulation by Colombo, and the discovery of valves in veins by Fabricius. Following these developments, Harvey described blood circulation.

Fine tuning of graphene-metal adhesion by surface alloying.

We show that bimetallic surface alloying provides a viable route for governing the interaction between graphene and metal through the selective choice of the elemental composition of the surface alloy. This concept is illustrated by an experimental and theoretical characterization of the properties of graphene on a model PtRu surface alloy on Ru(0001), with a concentration of Pt atoms in the first layer between 0 and 50%. The progressive increase of the Pt content determines the gradual detachment of graphene from the substrate, which results from the modification of the carbon orbital hybridization promoted by Pt. Alloying is also found to affect the morphology of graphene, which is strongly corrugated on bare Ru, but becomes flat at a Pt coverage of 50%. The method here proposed can be readily extended to several supports, thus opening the way to the conformal growth of graphene on metals and to a full tunability of the graphene-substrate interaction.

Surface structure of Pd(111) with less than half a monolayer of Zn.

We have characterized the structural properties of submonolayer amounts of Zn on Pd(111) using scanning tunneling microscopy (STM) and spot-profile analysis low energy electron diffraction (SPA-LEED). Following room temperature deposition of ≈0.06 monolayers (ML) Zn onto Pd(111), we observe the substitution of Zn for Pd in the surface layer. At ≈0.20 ML of deposited Zn, STM reveals a locally ordered phase with a (2/√3 × 2/√3)R30° unit cell located near Zn substitutions; SPA-LEED patterns reveal the same periodicity. We attribute this phase to the metastable bonding of atoms or clusters predominantly in hollow sites surrounding Zn substitutions in the surface layer. At ≈0.4 ML, STM images reveal local (√3 × âˆš3)R30° and (2 × 1) ordering on surfaces annealed to 350 K. At coverages near 0.5 ML, both STM and SPA-LEED show the onset of the formation of the (2 × 1) ordering associated with the Zn : Pd 1 : 1 alloy phase. At all coverages, the surface is dominated by island growth; the islands' size and density is shown to depend critically on annealing at temperatures as low as 350 K. These results provide insight into the structural features of a Zn/Pd(111) coverage regime that has been much debated in recent years.

Hyperfine structure of Ho3+ levels and electron-phonon coupling in YPO4 single crystals.

High resolution spectroscopy (the finest being 0.01 cm(-1)) was applied in the 75-25,000 cm(-1) and 9-300 K ranges to a 1 mol% holmium doped Y PO(4) single crystal with two purposes: (1) to study the hyperfine splitting of Ho(3+) energy levels of interest for possible quantum manipulation media and (2) to analyze the electron-phonon interaction. The hyperfine structure was clearly revealed for a high number of lines in a wide wavenumber range (up to ~21,500 cm(-1)) and for a large number of multiplets. Several hyperfine patterns were monitored, differing in the number of components (a maximum of 16 could be easily distinguished in a single beautiful pattern), in their separation, and in their relative statistical weight. These features were all understood in terms of a crystal-field model, whose results are in good agreement with experiments and account for the involved level symmetry, the type of transitions (electric and magnetic dipole allowed), and the contribution of a second-order (pseudoquadrupolar) hyperfine coupling between close levels. The electron-phonon interaction, investigated through the thermally induced line shift, was critically discussed in the framework of single phonon coupling and of two phonon Raman scattering models.

Thermal stability of corrugated epitaxial graphene grown on Re(0001).

We report on a novel approach to determine the relationship between the corrugation and the thermal stability of epitaxial graphene grown on a strongly interacting substrate. According to our density functional theory calculations, the C single layer grown on Re(0001) is strongly corrugated, with a buckling of 1.6 Å, yielding a simulated C 1s core level spectrum which is in excellent agreement with the experimental one. We found that corrugation is closely knit with the thermal stability of the C network: C-C bond breaking is favored in the strongly buckled regions of the moiré cell, though it requires the presence of diffusing graphene layer vacancies.

Hematologic improvement and response in elderly AML/RAEB patients treated with valproic acid and low-dose Ara-C.

The histone deacetylase inhibitor (HDACi) valproic acid (VPA) has been shown to be active on acute myeloid leukemia (AML) and refractory anemia with excess of blasts (RAEB). Thirty-one elderly AML/RAEB patients (AML n=25; RAEB n=6) with a high rate of comorbidity were entered in a phase II study with low-dose cytarabine (Ara-C) and VPA. Fitness was evaluated by means of the Comprehensive Geriatric Assessment (CGA), including the Cumulative Illness Rating Scale (CIRS) score, the self-sufficiency scores of Activity of Daily Living (ADL) and Instrumental Activity of Daily Living (IADL). Eight patients obtained a lasting complete remission and 3 other patients obtained hematologic improvement for a total response rate of 35%. Five of 11 responding patients were relapsed or resistant after a previous treatment with Ara-C. Seven of 11 responding patients were assessed as frail at enrollment and/or had IADL impairment. Grades 3 and 4 toxicities were mainly hematological. Low-dose Ara-C and VPA is a relatively non-toxic combination with good therapeutic activity in elderly patients with AML/RAEB. This therapeutic approach represents an alternative treatment for patients who cannot undergo standard induction therapy.

O- and H-induced surface core level shifts on Ru(0001): prevalence of the additivity rule.

In previous work on adsorbate-induced surface core level shifts (SCLSs), the effects caused by O atom adsorption on Rh(111) and Ru(0001) were found to be additive: the measured shifts for first-layer Ru atoms depended linearly on the number of directly coordinated O atoms. Density-functional theory calculations quantitatively reproduced this effect, allowed separation of initial- and final-state contributions, and provided an explanation in terms of a roughly constant charge transfer per O atom. We have now conducted similar measurements and calculations for three well-defined adsorbate and coadsorbate layers containing O and H atoms: (1 × 1)-H, (2 × 2)-(O+H) and (2 × 2)-(O+3H) on Ru(0001). As H is stabilized in fcc sites in the prior two structures and in hcp sites in the latter, this enables us to not only study coverage and coadsorption effects on the adsorbate-induced SCLSs, but also the sensitivity to similar adsorption sites. Remarkably good agreement is obtained between experiment and calculations for the energies and geometries of the layers, as well as for all aspects of the SCLS values. The additivity of the next-neighbor adsorbate-induced SCLSs is found to prevail even for the coadsorbate structures. While this confirms the suggested use of SCLSs as fingerprints of the adsorbate configuration, their sensitivity is further demonstrated by the slightly different shifts unambiguously determined for H adsorption in either fcc or hcp hollow sites.

Carbon monoxide dissociation on Rh nanopyramids.

CO dissociation on rhomboidal faceted nanopyramids, produced on Rh(110) by fine-tuning of ion irradiation conditions, has been studied by high resolution core-level spectroscopy. We find that this morphology presents a large efficiency towards CO dissociation, a process which is inhibited on flat (110) terraces. We also measured the reactivity of nanostructures bound by different artificial step distributions identifying the sites responsible for the molecular bond disruption in the undercoordinated (n=6) edges running along the [11[over ]2] equivalent directions, with CO sitting in on-top configuration.