Energy loss function of samarium.

We present a combined experimental and theoretical work to obtain the energy loss function (ELF) or the excitation spectrum of samarium in the energy loss range between 3 and 200 eV. At low loss energies, the plasmon excitation is clearly identified and the surface and bulk contributions are distinguished. For the precise analysis the frequency-dependent energy loss function and the related optical constants (n and k) of samarium were extracted from the measured reflection electron energy loss spectroscopy (REELS) spectra by the reverse Monte Carlo method.

Long-Term Aging of Concentrated Aqueous Graphene Oxide Suspensions Seen by Rheology and Raman Spectroscopy.

Today, graphene oxide (GO) has gained well-deserved recognition, with its applications continuing to increase. Much of the processing of GO-based devices occurs in a dispersed form, which explains the commercialization of GO suspensions. Aging of these suspensions can, however, affect the shelf life and thus their application potential.

Preparation of TiO/WO/C/N Composite Nanofibers by Electrospinning Using Precursors Soluble in Water and Their Photocatalytic Activity in Visible Light.

Extending the absorption range of TiO nanofibers to visible light is a great improvement of the photocatalytic property of TiO. In this study, TiO/WO/C/N nanofibers were prepared by electrospinning using precursors soluble in water then annealing in argon. Titanium(IV) bis(ammonium lactato)dihydroxide (TiBALDH) and ammonium metatungstate (AMT) were used as the precursor for TiO and WO respectively.

Hydrothermal Synthesis and Gas Sensing of Monoclinic MoO Nanosheets.

Effects of different reaction parameters in the hydrothermal synthesis of molybdenum oxides (MoO) were investigated and monoclinic (β-) MoO was prepared hydrothermally for the first time. Various temperatures (90/210 °C, and as a novelty 240 °C) and durations (3/6 h) were used. At 240 °C, cetyltrimethylammonium bromide (CTAB) and CrCl additives were also tested.

Effect of pH in the Hydrothermal Preparation of BiWO Nanostructures.

In this study, BiWO was prepared by the hydrothermal method. The effects of reaction temperature (150/170/200 °C) and reaction time (6/12/24 h) were investigated. The role of strongly acidic pH (1 >) and the full range between 0.

Robustness of Griffiths effects in homeostatic connectome models.

I provide numerical evidence for the robustness of the Griffiths phase (GP) reported previously in dynamical threshold model simulations on a large human brain network with N=836733 connected nodes. The model, with equalized network sensitivity, is extended in two ways: introduction of refractory states or by randomized time-dependent thresholds. The nonuniversal power-law dynamics in an extended control parameter region survives these modifications for a short refractory state and weak disorder.

Effect of Different Anions Upon the WO₃ Morphology and Structure.

In this study the effects of various anions (SO₄, ClO₄ and PO₄) were investigated on the hydrothermal treatment of WO₃ from Na₂WO₄ and HCl at 180 and 200 °C. The products were analyzed by XRD and SEM. With the usage of SO₄ the obtained product was hexagonal (h-) WO₃ in the form of nanorods at both temperatures.

Nanobody-Displaying Flagellar Nanotubes.

In this work we addressed the problem how to fabricate self-assembling tubular nanostructures displaying target recognition functionalities. Bacterial flagellar filaments, composed of thousands of flagellin subunits, were used as scaffolds to display single-domain antibodies (nanobodies) on their surface. As a representative example, an anti-GFP nanobody was successfully inserted into the middle part of flagellin replacing the hypervariable surface-exposed D3 domain.

Griffiths effects of the susceptible-infected-susceptible epidemic model on random power-law networks.

We provide numerical evidence for slow dynamics of the susceptible-infected-susceptible model evolving on finite-size random networks with power-law degree distributions. Extensive simulations were done by averaging the activity density over many realizations of networks. We investigated the effects of outliers in both highly fluctuating (natural cutoff) and nonfluctuating (hard cutoff) most connected vertices.

Griffiths phases and localization in hierarchical modular networks.

We study variants of hierarchical modular network models suggested by Kaiser and Hilgetag [ Front. in Neuroinform., 4 (2010) 8] to model functional brain connectivity, using extensive simulations and quenched mean-field theory (QMF), focusing on structures with a connection probability that decays exponentially with the level index.

Structure-color-species correlation in photonic nanoarchitectures occurring in blue lycaenid butterfly scales.

The blue colored males of nine Polyommatine butterfly species were investigated under the aspect of color-structure-species correlation. A large number of individuals from museum collections (in total more than 100) were used to obtain average reflectance spectra to reduce the effect of individual variations as much as possible. Structural characteristics were investigated by scanning electron microscopy and transmission electron microscopy.

Distribution patterns of different carbon nanostructures in silicon nitride composites.

The dispersion properties of single- and multi-walled carbon nanotubes as well as mechanically exfoliated few layer graphene flakes within the silicon nitride ceramic matrix have been investigated. Small angle neutron scattering experiments have been employed to gain information on the dispersion of the nano-scale carbon fillers throughout the entire volume of the samples. The neutron scattering data combined with scanning electron microscopy revealed strikingly different distribution patterns for different types of carbon nanostructures.

Simulation of the backscattered electron intensity of multi layer structure for the explanation of secondary electron contrast.

The intensities of the secondary electrons (SE) and of the backscattered electrons (BSE) at energy 100 eV have been measured on a Ni/C/Ni/C/Ni/C/(Si substrate) multilayer structure by exciting it with primary electrons of 5, 2.5 and 1.25 keV energies.

Various nanostructures on macroscopically large areas prepared by tunable ion-swelling.

Various nanostructures were fabricated by ion irradiation on large area (100) Si surfaces covered by colloidal Langmuir-Blodgett films as nanolithographic masks. The ordered structure of the Langmuir-Blodgett monolayer composed from spherical Stöber silica particles of 200 nm and 450 nm diameter offer the possibility to form local surface swelling patterns during the ion bombardment step. Utilizing the dependence of the surface morphology on the irradiation parameters the tunability of nanostructuring was studied for 40 keV Ar+ and 500 keV Xe2+ ions.

Formation of nanoparticles by ion beam irradiation of thin films.

The possibility of fabricating nanoparticles by ion bombardment was investigated by the ion bombardment of indium films on oxide covered Si and Cr surfaces. The different masses of implanting specimen ensured the different energy transfer while the same Si substrate ensured the same thermal conductivity for the In and Cr layers. Chromium served as a reference for the effect of ion bombardment and as a substrate as well.

Conditional strategies and the evolution of cooperation in spatial public goods games.

The fact that individuals will most likely behave differently in different situations begets the introduction of conditional strategies. Inspired by this, we study the evolution of cooperation in the spatial public goods game, where, besides unconditional cooperators and defectors, also different types of conditional cooperators compete for space. Conditional cooperators will contribute to the public good only if other players within the group are likely to cooperate as well but will withhold their contribution otherwise.

Electron diffraction based analysis of phase fractions and texture in nanocrystalline thin films, part III: application examples.

In this series of articles, a method is presented that performs (semi)quantitative phase analysis for nanocrystalline transmission electron microscope samples from selected area electron diffraction (SAED) patterns. Volume fractions and degree of fiber texture are determined for the nanocrystalline components. The effect of the amorphous component is minimized by empirical background interpolation.

Group-size effects on the evolution of cooperation in the spatial public goods game.

We study the evolution of cooperation in public goods games on the square lattice, focusing on the effects that are brought about by different sizes of groups where individuals collect their payoffs and search for potential strategy donors. We find that increasing the group size does not necessarily lead to mean-field behavior, as is traditionally observed for games governed by pairwise interactions, but rather that public cooperation may be additionally promoted by means of enhanced spatial reciprocity that sets in for very large groups. Our results highlight that the promotion of cooperation due to spatial interactions is not rooted solely in having restricted connections among players, but also in individuals having the opportunity to collect payoffs separately from their direct opponents.

Competition of individual and institutional punishments in spatial public goods games.

We have studied the evolution of strategies in spatial public goods games where both individual (peer) and institutional (pool) punishments are present in addition to unconditional defector and cooperator strategies. The evolution of strategy distribution is governed by imitation based on the random sequential comparison of neighbors' payoff for a fixed level of noise. Using numerical simulations, we evaluate the strategy frequencies and phase diagrams when varying the synergy factor, punishment cost, and fine.

Graphene: nanoscale processing and recent applications.

One of the most interesting features of graphene is the rich physics set up by the various nanostructures it may adopt. The planar structure of graphene makes this material ideal for patterning at the nanoscale. The breathtakingly fast evolution of research on graphene growth and preparation methods has made possible the preparation of samples with arbitrary sizes.

Plan-view preparation of TEM specimens from thin films using adhesive tape.

A simple plan-view sample preparation technique for transmission electron microscopy (TEM) specimens is proposed for thin films by tearing-off the film with adhesive tape. The demand for very thin samples is highest for nanostructured materials where the structure of 2-5 nm sized features (grains) needs to be resolved; therefore, overlapping of nanometer-sized features should be avoided. The method provides thin areas at the fracture edges of plan-view specimens with thickness in the range of the grain size in the film allowing for artifact free high-resolution TEM imaging.

Microscopic study of electrical properties of CrSi2 nanocrystals in silicon.

Semiconducting CrSi2 nanocrystallites (NCs) were grown by reactive deposition epitaxy of Cr onto n-type silicon and covered with a 50-nm epitaxial silicon cap. Two types of samples were investigated: in one of them, the NCs were localized near the deposition depth, and in the other they migrated near the surface. The electrical characteristics were investigated in Schottky junctions by current-voltage and capacitance-voltage measurements.

Phase diagrams for the spatial public goods game with pool punishment.

The efficiency of institutionalized punishment is studied by evaluating the stationary states in the spatial public goods game comprising unconditional defectors, cooperators, and cooperating pool punishers as the three competing strategies. Fines and costs of pool punishment are considered as the two main parameters determining the stationary distributions of strategies on the square lattice. Each player collects a payoff from five five-person public goods games, and the evolution of strategies is subsequently governed by imitation based on pairwise comparisons at a low level of noise.

Selfishness, fraternity, and other-regarding preference in spatial evolutionary games.

Spatial evolutionary games are studied with myopic players whose payoff interest, as a personal character, is tuned from selfishness to other-regarding preference via fraternity. The players are located on a square lattice and collect income from symmetric two-person two-strategy (called cooperation and defection) games with their nearest neighbors. During the elementary steps of evolution a randomly chosen player modifies her strategy in order to maximize stochastically her utility function composed from her own and the co-players' income with weight factors 1-Q and Q.