Change of the surface electronic structure of Au(111) by a monolayer MgO(001) film

Monolayer films of MgO(001) have been prepared on an Au(111) surface and explored by means of scanning tunneling microscopy (STM) and spectroscopy. The symmetry mismatch between the hexagonal substrate and the squared overlayer results in the formation of a (6 × 1) superlattice, as revealed from the distinct stripe pattern observed in the STM images. The presence of the oxide film also modifies the potential situation at the interface, which induces a substantial upshift of the Shockley-type surface band on Au(111). The resulting MgO/Au interface band is characterized by a pseudogap at around 500 mV that opens at the position of the new Brillouin zone of the enlarged (6 × 1) unit cell. In addition the oxide layer gives rise to a drastic decrease of the Au(111) work function, as deduced from the energy position of the first field-emission resonance on the bare and MgO-covered surface. The work-function drop is explained by an interfacial charge transfer from the oxide film into the electro-negative gold surface

Effect of a Klamath algae product ("AFA-B12") on blood levels of vitamin B12 and homocysteine in vegan subjects: a pilot study

none8Vitamin B12 is a critical nutrient that is often inadequate in a plant-based (vegan) diet, thus the inclusion of a reliable vitamin B12 source in a vegan diet is recommended as essential. Unfortunately, many natural sources of vitamin B12 have been proven to contain biologically inactive vitamin B12 analogues, inadequate for human supplementation. The aim of this non-randomized open trial was to determine whether supplementation with a natural Klamath algae-based product ("AFA-B12", Aphanizomenon flos-aquae algae plus a proprietary mix of enzymes) could favorably affect the vitamin B12 status of a group of 15 vegan subjects. By assessing blood concentration of vitamin B12, folate, and more importantly homocysteine (Hcy, a reliable marker in vegans of their B12 absorption), the vitamin B12 status of the participants at the end of the 3-month intervention period, while receiving the Klamath-algae supplement (T2), was compared with their vitamin B12 status at the end of the 3-month control period (T1), when they were not receiving any supplement, having stopped taking their usual vitamin B12 supplement at the beginning of the study (T0). Compared to the control period, in the intervention period participants improved their vitamin B12 status, significantly reducing Hcy blood concentration (p=0.003). In conclusion, the Klamath algae product AFA-B12 appears to be, in a preliminary study, an adequate and reliable source of vitamin B12 in humans.openL.Baroni; S.Scoglio; S.Benedetti; C.Bonetto; S.Pagliarani; Y.Benedetti; M.Rocchi; F.CanestrariL., Baroni; S., Scoglio; Benedetti, Serena; C., Bonetto; S., Pagliarani; Y., Benedetti; Rocchi, MARCO BRUNO LUIGI; Canestrari, Franc

Relative contributions of lattice distortion and orbital ordering to resonant x-ray scattering in manganites

We investigated the origin of the energy splitting observed in the resonant x-ray scattering (RXS) in manganites. Using thin film samples with controlled lattice parameters and orbital states at a fixed orbital filling, we estimated that the contribution of the interatomic Coulomb interaction relative to the Jahn-Teller mechanism is insignificant and at most 0.27. This indicates that RXS probes mainly Jahn-Teller distortion in manganites.Comment: 8 pages, 4 figure

Transcription-induced supercoiling explains formation of self-interacting chromatin domains in S. pombe.

The question of how self-interacting chromatin domains in interphase chromosomes are structured and generated dominates current discussions on eukaryotic chromosomes. Numerical simulations using standard polymer models have been helpful in testing the validity of various models of chromosome organization. Experimental contact maps can be compared with simulated contact maps and thus verify how good is the model. With increasing resolution of experimental contact maps, it became apparent though that active processes need to be introduced into models to recapitulate the experimental data. Since transcribing RNA polymerases are very strong molecular motors that induce axial rotation of transcribed DNA, we present here models that include such rotational motors. We also include into our models swivels and sites for intersegmental passages that account for action of DNA topoisomerases releasing torsional stress. Using these elements in our models, we show that transcription-induced supercoiling generated in the regions with divergent-transcription and supercoiling relaxation occurring between these regions are sufficient to explain formation of self-interacting chromatin domains in chromosomes of fission yeast (S. pombe)

Molecular basis of sweet taste in dipeptide taste ligands

Abstract In this presentation, we describe an integrated approach for the molecular basis for sweet taste among dipeptide-based ligands. By comparing the results obtained from X-ray diffraction studies with the conformations from NMR analysis and molecular modeling, we have observed recurring topochemical motifs that agree with previous models for sweet taste. In our examination of the unexplored D zone of the Tinti­Nofre model, we have uncovered a sweet potency enhancing effect of a new set of aralkyl-substitutions on dipeptide ligands, which reveals the importance of aromatic­aromatic interactions in maintaining high potency

Validation of a globally-applicable method to measure urban tolerance of birds using citizen science data

Understanding species-specific responses to urbanization is essential to mitigate and preserve biodiversity in the face of increasing urbanization, but a major challenge is how to estimate urban tolerances for a wide array of species applicable over disparate regions. A promising approach is to assess urban tolerance by integrating geo-referenced information on species detections from citizen science data with estimations of urbanization intensity based on remotely-sensed night-time lights. While such citizen science urbanness scores (CSUS) are cost-effective, intuitive, and easily-repeatable anywhere in the world, whether the scores accurately describe urban tolerance still awaits empirical verification. By analysing >900 bird species worldwide, we find that CSUS correlates well with a standard measure of urban tolerance based on changes in abundance between urbanized and non-urbanized nearby habitats. Our analyses show that there is substantial variability in the relationship between these two metrics, but nevertheless highlights the potential for the CSUS approach in the future. Future improvements to the index, including incorporating rare species, and understanding the influence of intra-specific variability in response to urbanization, will be necessary to maximize the broad utility of the approach

A new method to prepare composite powders customized for high temperature laser sintering

This is the final version of the article. Available from Elsevier via the DOI in this record.Composites have the potential to enhance the mechanical properties of components fabricated by additive manufacturing; however, the bottleneck is the limited number of polymeric composite powders available for this manufacturing process. This paper describes a generically new method to create composite powders that are suitable for High Temperature Laser Sintering (HT-LS). C-coated Inorganic Fullerene-like WS2 (IF-WS2) nanoparticles and graphene nanoplatelets (GNPs) have been chosen to demonstrate their incorporation into a high performance polymer matrix: Poly Ether Ether Ketone (PEEK). The morphological and physical property investigations have confirmed that the resulting composite powders exhibit the desired particle morphology, size, distribution and flowability for HT-LS applications. Further preliminary sintering results have demonstrated that they are comparable to the currently available commercial grade of PEEK powder HT-LS applications in terms of powder packing properties and flow ability. The new strategy reported here brings in great potential for the additive layer manufacturing of high performance polymeric composite components with improved mechanical and added functionalities by choosing the proper matrix and filler combination.Thank the EPSRC (EP/N034627/1) for financial support

Fabrication of nanocomposite powders with a core-shell structure

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.This study presents a new process for producing nanocomposite powders for use in various manufacturing processes such as laser sintering or dry powder impregnation techniques for thermoplastic composites manufacture. Polyetherimide (PEI) was used as a polymeric coating/shell to encapsulate nanoparticles on the surface of poly ether ether ketone (PEEK) particles, which were used as a core matrix. Nanoparticles with different morphologies, known to enhance thermal and electrical performance of polymers: 2D graphene nanoplatelets (GNPs) and inorganic fullerene-like tungsten disulfide (IF-WS2) in different concentrations (0.1, 1, and 5 wt%) were incorporated in the shell structures. The coated powders had approximately the same particle size distribution as the uncoated, plain powders, which is an indication that the shell was in nm size and the coating process did not affect the overall size of the particles. Furthermore, the core-shell particles exhibit a smoother surface and an improved flowability after coating. The Transmission Electron Microscopy (TEM) images of the nanocomposite particles cross-section area confirmed the formation of core-shell structure, and the presence of the nanoparticles embedded into the shell layer. The scanning electron microscopy (SEM) images showed a homogeneous distribution of nanoparticles within the coating layer at lower nanoparticle concentrations (0.1 and 1 wt%)Engineering and Physical Sciences Research Council (EPSRC

Cooperative Jahn-Teller transition and resonant x-ray scattering in thin film LaMnO3{\rm LaMnO_3}

Epitaxial thin films of stoichiometric ${\rm LaMnO_3}$ were grown on ${\rm SrTiO_3(110)}$ substrates using the pulsed laser deposition technique. From the high resolution x-ray diffraction measurements, the lattice parameters were determined as a function of temperature and the cooperative Jahn-Teller transition was found to occur at $T_{JT}$=573.0 K. Also measured was resonant x-ray scattering intensity of the orthorhombic (100) peak of ${\rm LaMnO_3}$ near the Mn K edge from low temperatures to above $T_{JT}$. We demonstrate that the integrated intensity of the (100) peak is proportional to the 3/2 power of the orthorhombic strain at all temperatures, and thus provide an experimental evidence that the resonant scattering near the Mn K edge in ${\rm LaMnO_3}$ is largely due to the Jahn-Teller effect.Comment: 13 pages, 4 figure

Compactness for Holomorphic Supercurves

We study the compactness problem for moduli spaces of holomorphic supercurves which, being motivated by supergeometry, are perturbed such as to allow for transversality. We give an explicit construction of limiting objects for sequences of holomorphic supercurves and prove that, in important cases, every such sequence has a convergent subsequence provided that a suitable extension of the classical energy is uniformly bounded. This is a version of Gromov compactness. Finally, we introduce a topology on the moduli spaces enlarged by the limiting objects which makes these spaces compact and metrisable.Comment: 38 page