Abstract: Electronic states are responsible for most material properties, including chemical bonds, electrical and thermal conductivity, as well as optical and magnetic properties. Experimentally, however, they remain mostly elusive. Here, we report the real-space mapping of selected transitions between p and d states on the Ångström scale in bulk rutile (TiO2) using electron energy-loss spectrometry (EELS), revealing information on individual bonds between atoms. On the one hand, this enables the experimental verification of theoretical predictions about electronic states. On the other hand, it paves the way for directly investigating electronic states under conditions that are at the limit of the current capabilities of numerical simulations such as, e.g., the electronic states at defects, interfaces, and quantum dots.

Abstract: A joint action of ssDNA aptamers and electrochemistry is a key element in developing successful biosensing platforms, since aptamers are capable of binding various targets with high specificity, and electrochemistry is one of the most sensitive techniques for on-site detections. A continuous search for improved immobilization and sensing strategies of aptamers on transducer surfaces resulted in the strategy presented in this article. The strategy is based on the covalent attachment of gold nanoparticles on the surface of glassy carbon electrodes through sulfhydryl-terminated monolayer, acting as a glue to connect AuNPs on the electrode. The covalently attached gold nanoparticles modified glassy carbon electrodes have been applied for the efficient immobilization of thiolated ssDNA probes, with a surface coverage of about 8.54 × 1013 molecules cm−2 which was 7-fold higher than that on the electrochemically deposited gold nanoparticles. Consequently, improved sensitivity, good reproducibility and stability are achieved for electrochemical aptasensor. Combined with the high affinity and specificity of an aptamer, a simple, novel, rapid, sensitive and label-free electrochemical aptasensor was successfully fabricated for ofloxacin (OFL) detection. The linear dynamic range of the sensor varies between 5 × 10−8 to 2 × 10−5 M OFL with a detection limit of 1 × 10−9 M OFL. A potential application in environmental monitoring was demonstrated by using this sensing strategy for the determination of OFL in (experimentally spiked) real samples such as tap water and effluent of sewage treatment plant. The proposed nanoaptasensor combines the advantages of the covalent attachment of neatly arranged AuNPs (enlarged active surface area and strengthened electrochemical signal) and the elimination of labels for the amplified detection of OFL, with the covalent attachment of highly specific aptamers to the surface of the modified electrode.

Abstract: Dielectric Barrier Discharges operating in CO and CO2 form solid products at atmospheric pressure. The main differences between both plasmas and their deposits were analyzed, at similar energy input. GC measurements revealed a mixture of CO2, CO, and O2 in the CO2 DBD exhaust, while no O2 was found in the CO plasma. A coating of nanoparticles composed of Fe, O, and C was produced by the CO2 discharge, whereas, a microscopic dendrite-like carbon structure was formed in the CO plasma. Fe3O4 and Fe crystalline phases were found in the CO2 sample. The CO
deposition was characterized as an amorphous structure, close to polymeric CO (p-CO). Interestingly, p-CO is not formed in the CO2 plasma, in spite of the significant amounts of CO produced (up to 30% in the reactor exhaust).

Abstract: Plasma–liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on nonequilibrium plasmas.

Abstract: Ceria nanoparticles (NPs) are fundamental in heterogeneous catalysis because of their ability to store or release oxygen depending on the ambient conditions. Their oxygen storage capacity is strictly related to the exposed planes, crystallinity, density and distribution of defects. In this work a study of ceria NPs produced with a ligand-free, physical synthesis method is presented. The NP films were grown by a magnetron sputtering based gas aggregation source and studied by high resolution- and scanning-transmission electron microscopy and x-ray photoelectron spectroscopy. In particular, the influence of the oxidation procedure on the NP reducibility has been investigated. The different reducibility has been correlated to the exposed planes, crystallinity and density and distribution of structural defects. The results obtained in this work represent a basis to obtain cerium oxide NP with desired oxygen transport properties.

Abstract: The use of phase plates in the back focal plane of a microscope is a well-established technique in optical microscopy to increase the contrast of weakly interacting samples and is gaining interest in electron microscopy as well. In this paper we study the spiral phase plate (SPP), also called helical, vortex, or two-dimensional Hilbert phase plate, which adds an angularly dependent phase of the form exp(iℓϕk) to the exit wave in Fourier space. In the limit of large collection angles, we analytically calculate that the average of a pair of l=+-1
SPP filtered images is directly proportional to the gradient squared of the exit wave, explaining the edge contrast previously seen in optical SPP work. We discuss the difference between a clockwise-anticlockwise pair of SPP filtered images and derive conditions under which the modulus of the wave's gradient can be seen directly from one SPP filtered image. This work provides the theoretical background to interpret images obtained with a SPP, thereby opening new perspectives for new experiments to study, for example, magnetic materials in an electron microscope.

Abstract: The fabrication of n-type diamond is essential for the realization of electronic components for extreme environments. We report on the growth of a 66 mu m thick homoepitaxial phosphorus-doped diamond on a (110)-oriented diamond substrate, grown at a very high deposition rate of 33 mu m h(-1). A pristine diamond lattice is observed by high resolution transmission electron microscopy, which indicates the growth of high quality diamond. About 2.9 x 10(16) cm(-3) phosphorus atoms are electrically active as substitutional donors, which is 60% of all incorporated dopant atoms. These results indicate that P-doped (110)-oriented diamond films deposited at high growth rates are promising candidates for future use in high-power electronic applications. Published by AIP Publishing.

Abstract: The true function of neuroglobin (Ngb) and, particularly, human Ngb (NGB) has been under debate since its discovery 15 years ago. It has been expected to play a role in oxygen binding/supply, but a variety of other functions have been put forward, including NO dioxygenase activity. However, in vitro studies that could unravel these potential roles have been hampered by the lack of an Ngb-specific reductase. In this work, we used electrochemical measurements to investigate the role of an intermittent internal disulfide bridge in determining NO oxidation kinetics at physiological NO concentrations. The use of a polarized electrode to efficiently interconvert the ferric (Fe3+) and ferrous (Fe2+) forms of an immobilized NGB showed that the disulfide bridge both defines the kinetics of NO dioxygenase activity and regulates appearance of the free ferrous deoxy-NGB, which is the redox active form of the protein in contrast to oxy-NGB. Our studies further identified a role for the distal histidine, interacting with the hexacoordinated iron atom of the heme, in oxidation kinetics. These findings may be relevant in vivo, for example in blocking apoptosis by reduction of ferric cytochrome c, and gentle tuning of NO concentration in the tissues.

Abstract: Ginzburg-Landau theory is one of the most powerful phenomenological theories in physics, with particular predictive value in superconductivity. The formalism solves coupled nonlinear differential equations for both the electronic and magnetic responsiveness of a given superconductor to external electromagnetic excitations. With order parameter varying on the short scale of the coherence length, and the magnetic field being long-range, the numerical handling of 3D simulations becomes extremely challenging and time-consuming for realistic samples. Here we show precisely how one can employ graphics-processing units (GPUs) for this type of calculations, and obtain physics answers of interest in a reasonable time-frame – with speedup of over 100x compared to best available CPU implementations of the theory on a 2563grid. (C) 2016 Elsevier Inc. All rights reserved.

Abstract: Pulsed laser deposited thin YBa2Cu3O7−x (YBCO) films with pinning additions of 5at.% Ba2YTaO6 (BYTO) were compared to films with 2.5at.% Ba2YTaO6 + 2.5at.% Ba2YNbO6 (BYNTO) additions. Excellent magnetic flux-pinning at 77 K was obtained with remarkably high irreversibility fields greater than 10T (YBCO-BYTO) and 11T (YBCO-BYNTO), representing the highest ever achieved values in YBCO films.

Abstract: Transmission electron microscopy was performed to investigate the microstructures of a secondary phase and its surrounding matrix in a Co38Ni33Al29 ferromagnetic shape memory alloy. The secondary phase shows a γ′ L12 structure exhibiting a dendritic morphology with enclosed B2 austenite regions while the matrix shows the L10 martensitic structure. A secondary phase-austenite-martensite sandwich structure with residual austenite ranging from several hundred nanometers to several micrometers wide is observed at the secondary phase-martensite interface due to the depletion of Co and enrichment of Al in the chemical gradient zone and the effect of the strong martensitic start temperature dependency of the element concentrations. The crystallographic orientation relationship of the secondary phase and the B2 austenite fits the Kurdjumov-Sachs relationship.

Abstract: Studying protein interactions is of vital importance both to fundamental biology research and to medical applications. Here, we report on the experimental proof of a universally applicable label-free homogeneous platform for rapid protein analysis. It is based on optically detecting changes in the rotational dynamics of magnetically agitated core-shell nanorods upon their specific interaction with proteins. By adjusting the excitation frequency, we are able to optimize the measurement signal for each analyte protein size. In addition, due to the locking of the optical signal to the magnetic excitation frequency, background signals are suppressed, thus allowing exclusive studies of processes at the nanoprobe surface only. We study target proteins (soluble domain of the human epidermal growth factor receptor 2 – sHER2) specifically binding to antibodies (trastuzumab) immobilized on the surface of our nanoprobes and demonstrate direct deduction of their respective sizes. Additionally, we examine the dependence of our measurement signal on the concentration of the analyte protein, and deduce a minimally detectable sHER2 concentration of 440 pM. For our homogeneous measurement platform, good dispersion stability of the applied nanoprobes under physiological conditions is of vital importance. To that end, we support our measurement data by theoretical modeling of the total particle-particle interaction energies. The successful implementation of our platform offers scope for applications in biomarker-based diagnostics as well as for answering basic biology questions.

Abstract: We present two-dimensional Mg(OH)(2) sheets and their vertical heterojunctions with CVD-MoS2 for the first time as flexible 2D insulators with anomalous lattice vibration and chemical and physical properties. New hydrothermal crystal growth technique enabled isolation of environmentally stable monolayer Mg(OH)(2) sheets. Raman spectroscopy and vibrational calculations reveal that the lattice vibrations of Mg(OH)(2) have fundamentally different signature peaks and dimensionality effects compared to other 2D material systems known to date. Sub-wavelength electron energy-loss spectroscopy measurements and theoretical calculations show that Mg(OH)(2) is a 6 eV direct-gap insulator in 2D, and its optical band gap displays strong band renormalization effects from monolayer to bulk, marking the first experimental confirmation of confinement effects in 2D insulators. Interestingly, 2D-Mg(OH)(2) sheets possess rather strong surface polarization (charge) effects which is in contrast to electrically neutral h-BN materials. Using 2D-Mg(OH)(2) sheets together with CVD-MoS2 in the vertical stacking shows that a strong change transfer occurs from n-doped CVD-MoS2 sheets to Mg(OH)(2), naturally depleting the semiconductor, pushing towards intrinsic doping limit and enhancing overall optical performance of 2D semiconductors. Results not only establish unusual confinement effects in 2D-Mg(OH)(2), but also offer novel 2D-insulating material with unique physical, vibrational, and chemical properties for potential applications in flexible optoelectronics.

Abstract: Utilization of flue gas for algae cultivation seems to be a promising route because flue gas from fossil-fuel combustion processes contains the high amounts of carbon (CO2) and nitrogen (NO) that are required for algae growth. NO is a poor nitrogen source for algae cultivation because of its low reactivity and solubility in water and its toxicity for algae at high concentrations. Here, we present a novel strategy to valorize NO from flue gas as feedstock for algae production by combining a photocatalytic gas pretreatment unit with a microalgal photobioreactor. The photocatalytic air pretreatment transforms NO gas into NO2 gas and thereby enhances the absorption of NO in the cultivation broth. The absorbed NOx will form NO2- and NO3- that can be used as a nitrogen source by algae. The effect of photocatalytic air pretreatment on the growth and biomass productivity of the algae Thalassiosira weissflogii in a semicontinuous system aerated with a model flue gas (1% CO2 and 50 ppm of NO) is investigated during a long-term experiment. The integrated system makes it possible to produce algae with NO from flue gas as the sole nitrogen source and reduces the NOx content in the exhaust gas by 84%.

Abstract: This work examines the properties of a dielectric barrier discharge (DBD) reactor, built for CO2 decomposition, by means of electrical characterization, optical emission spectroscopy and gas chromatography. The discharge, formed in an electronegative gas (such as CO2, but also O2), exhibits clearly different electrical characteristics, depending on the surface conductivity of the reactor walls. An asymmetric current waveform is observed in the metaldielectric (MD) configuration, with sparse high-current pulses in the positive half-cycle (HC) and a more uniform regime in the negative HC. This indicates that the discharge is operating in two alternating regimes with rather different properties. At high CO2 conversion regimes, a conductive coating is deposited on the dielectric. This so-called coated MD configuration yields a symmetric current waveform, with current peaks in both the positive and negative HCs. In a double-dielectric (DD) configuration, the current waveform is also symmetric, but without current peaks in both the positive and negative HC. Finally, the DD configuration with conductive coating on the inner surface of the outer dielectric, i.e. so-called coated DD, yields again an asymmetric current waveform, with current peaks in the negative HC. These different electrical characteristics are related to the presence of the conductive coating on the dielectric wall of the reactor and can be explained by an increase of the local barrier capacitance available for charge transfer. The different discharge regimes affect the CO2 conversion, more specifically, the CO2 conversion is lowest in the clean DD configuration. It is somewhat higher in the coated DD configuration, and still higher in the MD configuration. The clean and coated MD configuration, however, gave similar CO2 conversion. These results indicate that the conductivity of the dielectric reactor walls can highly promote the development of the high-amplitude discharge current pulses and subsequently the CO2 conversion.