Graphene oxides are promising materials for novel electronic devices or anchoring of the active sites for catalytic applications. Here we focus on understanding the atomic oxygen (AO) binding and ...mobility on different regions of graphene (Gr) on Ru(0001). Differences in the Gr/Ru lattices result in the superstructure, which offers an array of distinct adsorption sites. We employ scanning tunneling microscopy and density functional theory to map out the chemical identity and stability of prepared AO functionalities in different Gr regions. The AO diffusion is utilized to establish that in the regions that are close to the metal substrate the terminally bonded enolate groups are strongly preferred over bridge-bonded epoxy groups. No oxygen species are observed on the graphene regions that are far from the underlying Ru, indicating their low relative stability. This study provides a clear fundamental basis for understanding the local structural, electronic factors and C–Ru bond strengthening/weakening processes that affect the stability of enolate and epoxy species.
The reference surveillance method in patients with Barrett's esophagus is careful endoscopic observation, with targeted as well as random four-quadrant biopsies. Autofluorescence endoscopy (AFE) may ...make it easier to locate neoplasia. The aim of this study was to elucidate the diagnostic accuracy of surveillance with AFE-guided plus four-quadrant biopsies in comparison with the conventional approach.
A total of 187 of 200 consecutive Barrett's esophagus patients who were initially enrolled (73 % male, mean age 67 years, mean Barrett's segment length 4.6 cm), who underwent endoscopy for Barrett's esophagus in four study centers, were randomly assigned to undergo either AFE-targeted biopsy followed by four-quadrant biopsies or conventional endoscopic surveillance, also including four-quadrant biopsies (study phase 1). After exclusion of patients with early cancer or high-grade dysplasia, who underwent endoscopic or surgical treatment, as well as those who declined to participate in phase 2 of the study, 130 patients remained. These patients were examined again with the alternative method after a mean of 10 weeks, using the same methods described. The main study parameter was the detection of early cancer/adenocarcinoma or high-grade dysplasia (HGD), comparing both approaches in study phase 1; the secondary study aim in phase 2 was to assess the additional value of the AFE-guided approach after conventional surveillance, and vice versa. Test accuracy measures were derived from study phase 1.
In study phase 1, the AFE and conventional approaches yielded adenocarcinoma/HGD rates of 12 % and 5.3 %, respectively, on a per-patient basis. With AFE, four previously unrecognized adenocarcinoma/HGD lesions were identified (4.3 % of the patients); with the conventional approach, one new lesion (1.1 %) was identified. Of the 19 adenocarcinoma/HGD lesions detected during AFE endoscopy in study phase 1, eight were visualized, while 11 were only detected using untargeted four-quadrant biopsies (sensitivity 42 %). Of the 766 biopsies classified at histology as being nonneoplastic, 58 appeared suspicious (specificity 92 %, positive predictive value 12 %, negative predictive value 98.5 %). In study phase 2, AFE detected two further lesions in addition to the initial alternative approach in 3.2 % of cases, in comparison with one lesion with conventional endoscopy (1.7 %).
In this referral Barrett's esophagus population with a higher prevalence of neoplastic lesions, the AFE-guided approach improved the diagnostic yield for neoplasia in comparison with the conventional approach using four-quadrant biopsies. However, AFE alone was not suitable for replacing the standard four-quadrant biopsy protocol.
Summary
Background Constipation is a significant side effect of opioid therapy. We have previously demonstrated that naloxone‐3‐glucuronide (NX3G) antagonizes the motility‐lowering‐effect of ...morphine in the rat colon.
Aim To find out whether oral NX3G is able to reduce the morphine‐induced delay in colonic transit time (CTT) without being absorbed and influencing the analgesic effect.
Methods Fifteen male volunteers were included. Pharmacokinetics: after oral administration of 0.16 mg/kg NX3G, blood samples were collected over a 6‐h period. Pharmacodynamics: NX3G or placebo was then given at the start time and every 4 h thereafter. Morphine (0.05 mg/kg) or placebo was injected s.c. 2 h after starting and thereafter every 6 h for 24 h. CTT was measured over a 48‐h period by scintigraphy. Pressure pain threshold tests were performed.
Results Neither NX3G nor naloxone was detected in the venous blood. The slowest transit time was observed during the morphine phase, which was significantly different from morphine with NX3G and placebo. The pain perception was not significantly influenced by NX3G.
Conclusions Orally administered NX3G is able to reverse the morphine‐induced delay of CTT in humans without being detected in peripheral blood samples. Therefore, NX3G may improve symptoms of constipation in‐patients using opioid medication without affecting opioid‐analgesic effects.
The surface morphology and the lattice constants of NiO overlayers in the thickness range of 1–20 monolayers (NiO nanolayers) on Pd(1
0
0) have been investigated by high-resolution spot profile ...low-energy electron diffraction (SPA-LEED) and scanning tunneling microscopy (STM). NiO islands grow epitaxially on Pd(1
0
0) on top of a
c(4
×
2) Ni
3O
4 monolayer with a compressed strained lattice, which relaxes gradually attaining the bulk lattice constant at 10–12 monolayers. The strain relaxation is accompanied by the formation of small angle mosaic defect regions at the surface, which have been characterised quantitatively by following the behaviour of the satellites to the main Bragg diffraction rods. The analysis of the diffuse scattering intensity around the (0
0) diffraction spot reveals anisotropic NiO island shapes, whose orientation depends on the growth conditions. An incommensurate superlattice in LEED and STM at intermediate NiO coverages (∼2–6 monolayers) is observed and its origin is discussed.
A stoichiometric two-dimensional (2-D) WO3 layer has been fabricated by vapor-phase deposition of (WO3)3 clusters onto a Pd(100) surface and characterized by a combined experimental/theoretical ...multitechnique approach. The oxide forms a WO2 + O bilayer with a well-ordered c(2 × 2) structure, displaying at the full monolayer coverage a regular nanoscale pattern of antiphase domain boundaries, as revealed by low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) and rationalized by DFT analysis as a consequence of elastic strain relief. The stability of the WO2 + O bilayer is provided by polarity compensation via charge rearrangement at the WO3/Pd interface and allows for surface redox chemistry via reversible release and restoration of oxygen atoms of the tungstyl or WO groups.
The structure and properties of ternary oxide materials at the nanoscale are poorly explored both on experimental and theoretical levels. With this work we demonstrate the successful on-surface ...synthesis of two-dimensional (2D) ternary oxide, MnWOx and FeWOx, nanolayers on a Pd(1 0 0) surface and the understanding of their new structure and phase behaviour with the help of state-of-art surface structure and spectroscopy techniques. We find that the 2D MnWOx and FeWOx phases, prepared under identical thermodynamic conditions, exhibit similar structural properties, reflecting the similarity of the bulk MnWO4 and FeWO4 phases with the wolframite structure. Structure models of prototypical 2D ternary oxide phases are proposed and discussed in the light of new structure architecture concepts which have no analogues in the bulk.
The electronic structure of a bare Rh(553) surface and of a Ni-decorated Rh(553) surface has been investigated by angle-resolved UV photoelectron spectroscopy and density functional theory ...calculations. The self-assembly of Ni adatoms leads to the decoration of the steps of the Rh(553) surface with monoatomic Ni rows under suitable kinetic conditions, thus forming a regular array of pseudomorphic bimetallic Ni–Rh nanowires. The electronic structure of the clean Rh(553) surface has been compared to the one of the flat Rh(111) surface, and additional surface states localized at the step edges due to the lower coordination of the step atoms have been detected. The Ni wires are weakly hybridized with the Rh substrate states and are characterized by only weakly dispersing states. This leads to a strong narrowing of the
d-band, which is argued to be the origin of the observed high chemical reactivity of the Ni–Rh nanowires.
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