A great challenge in the field of neurocomputing is to mimic the brain behavior by implementing artificial synapses and neurons directly in hardware. This work shows that a Leaky Integrate and Fire (LIF) artificial neuron can be realized with a two-terminal device made of Mott insulator thin films. Polycrystalline thin films of the well-known Mott insulator oxide (V0.95Cr0.05)2O3 were deposited by magnetron sputtering and patterned with micron-scale TiN electrodes. These devices exhibit a volatile resistive switching and a remarkable LIF behavior under a train of pulses suggesting that LIF artificial neurons may be realized from (V0.95Cr0.05)2O3 thin films.

This work presents a study of the region of nanoparticle growth in an atmospheric pressure carbon arc. The nanoparticles are detected using the planar laser-induced incandescence technique. The measurements revealed large clouds of nanoparticles in the arc periphery bordering the region with a high density of diatomic carbon molecules. Two-dimensional computational fluid dynamic simulations of the arc combined with thermodynamic modeling show that this is due to the interplay of the condensation of carbon molecular species and the convection flow pattern. These results show that the nanoparticles are formed in the colder, peripheral regions of the arc and describe the parameters necessary for coagulation.

Kinetic Monte Carlo (KMC) models of complex materials and biomolecules are increasingly being constructed using molecular dynamics (MD). A KMC model contains a catalog of states and kinetic pathways, which enables study of the dynamics. The completeness of the catalog is crucial to the model accuracy and is linked to the quality of the MD data used for model construction. Therefore, quantifying the uncertainty due to missing states and pathways is important. A review on computational procedures available for on-the-fly KMC model construction using MD, uncertainty measurement, and algorithms for guiding further MD sampling in an accelerated manner is presented.

ZnO-based oxides are promising for thermoelectric energy generation at elevated temperatures. We study electrical transport properties of Ni-doped ZnO applying the density functional theory, indicating increase of the electrical conductivity (σ) and decrease of the Seebeck coefficient (S) due to Ni-doping, in full accordance with experimental results. We calculate the temperature-dependent σ and S applying the Boltzmann transport theory, approximating the electron relaxation time, τe. Good agreement with experimental data is obtained considering both temperature and energy dependence of τe. This yields explicit expressions for τe and provides us with powerful predictive tool assessing electronic transport in ZnO.

Robust evidences are presented showing that the Raman mode around 250 cm−1 in the Sb2Se3 thin films does not belong to this binary compound. The laser power density dependence of the Raman spectrum revealed the formation of Sb2O3 for high values of laser intensity power density excitation under normal atmospheric conditions. To complement this study, the Sb2Se3 films were characterized by x-ray diffraction during in situ annealing. Both these measurements showed that the Sb2Se3 compound can be replaced by Sb2O3. A heat-assisted chemical process explains these findings. Furthermore, Raman conditions required to perform precise measurements are described.

We investigate the impact of increasing number density of self-catalyzed GaAs nanowires (NWs) on their crystal structure, grown by molecular beam epitaxy. To this end, we employ an iterative, lithography-free approach for varying the number density of self-catalyzed GaAs NWs grown on Si(111) covered with native oxide. We use scanning electron microscopy and x-ray diffraction in combination with simulations based on the extended Markov model for the morphologic characterization of the so obtained NWs. Our findings show how both the shape of the Ga-droplet and the NW crystal structure are affected even by relatively small changes of the wire number density, allowing for a quantification of its influence on the local NW growth conditions at nominally identical growth parameters.

Perovskites solar cells have reached impressive efficiencies (22%) in recent years. Because certain environmental concerns are raised by the use of lead halides, there is an interest to seek out lead-free alternatives, featuring bismuth or antimony. Alongside, one of the major drawbacks displayed by MAPbI3 is their low stability at ambient conditions. In this work, (RP4)xBiyIz were synthesized, using different types of tetra-alkylphosphoniums (R4PI) were R = ethyl, butyl, hexyl, and octyl, to assess their stability. Afterwards, they were characterized to study their morphology and crystal structure, as well as their optical properties.

In this study, based on the collection process, three-dimensional aligned fiber scaffolds from gelatin and zein protein were manufactured using Forcespinning®. The homogeneous blending of gelatin:zein (1:4) showed improved tensile and good hydrophobic properties (water contact angle of 115 °C). Cell viability, adhesion, proliferation, and drug release were measured. The cell viability was studied with human fibroblasts and a low cytotoxic effect was observed. Berberine drug release was measured and sustained release rate was observed over 15 days. The morphologic features, prolonged drug release, and cytotoxicity results suggest that these fibers could be appropriate for drug delivery and tissue engineering applications.

We present for the first time the feasibility to recover the stiffness (here shear modulus) distribution of a three-dimensional heterogeneous sample using measured surface displacements and inverse algorithms without making any assumptions about local homogeneities and the stiffness distribution. We simulate experiments to create measured displacements and augment them with noise, significantly higher than anticipated measurement noise. We also test two-dimensional problems in plane strain with multiple stiff inclusions. Our inverse strategy recovers the shear modulus values in the inclusions and background well, and reveals the shape of the inclusion clearly.

In this study, a novel shape memory polymer (SMP), eggshell membrane (ESM), with macroscopic mesh structures and microscopic crosslinked protein fibers, has shown water-stimulated shape recovery characteristics. Our results show that the collagen triple-helical molecular chains and disulfide-rich motifs in the ESM function as net-points retaining essential structures during deformation, while hydrogen bonds play a key role as switch units for shape recovery through water stimulation. We also demonstrate that programmable shape recovery characteristics of ESM can be obtained by modulating the number of net-points. This study may inspire the design of new programmable SMPs.

Biosilica from living diatom microalgae has recently attracted the interest of the scientific community and found several applications in bio-nanotechnology. Among silica-maker organisms, diatom microalgae represent the most attractive marine microorganisms, featuring highly hierarchical, nanotextured and porous silica walls. These biologic structures, known as “frustules” are also chemically addressable via simple chemical synthesis. In this work, we propose new diatom-based hybrid materials consisting of biosilica extracted from living Thalassiosira weissflogii coated with polydopamine (PDA) films. The adhesion properties of the PDA were exploited to decorate the silica surface with silver nanoparticles. These multifunctional heterostructures can be useful for applications ranging from bioelectronics to biomedicine.

Photovoltaic organic semiconductors are emerging in many therapeutic applications, including drug delivery and optical control of cell function. However, for their safe use the possible concomitant elicitation of undesired responses in target cells need to be carefully evaluated. Here we describe molecular responses activated by semiconducting polymer nanoparticles based on poly(3-hexyl)thiophene (P3HT) in the model Hydra vulgaris, previously shown to respond to P3HT-NP photostimulation and showed a decrease in the total antioxidant capacity and an increase in the DNA and protein oxidation levels, paving the way to a novel use of photovoltaic devices to control intracellular redox equilibrium.

We present a first-principles investigation on the optical absorption of tungsten trioxide, an electrochromic material. Using state-of-the-art techniques, the absorption spectra are calculated for the cubic, monoclinic, and amorphous phases. For both crystalline and disordered structures, doping induces strong absorption in the infrared. Absorption in the visible range increases with the degree of structural distortion; the absorption coefficient in the blue exceeds 103 cm−1 at doping levels above 1020 cm−3 in the monoclinic phase. Increased disorder in disordered structures significantly enhances the visible-range absorption. We identify the microscopic mechanism as optical absorption originating at conduction-band-derived states that are filled by doping.

Herein, we show that scanning probe microscopy (SPM) is an effective tool permitting to disclose the nature of the colossal dielectric permittivity characteristic of CaCu3Ti4O12 (CCTO) compound. SPM data confirm the existence of micro- and nanoscale barrier layer capacitance mechanisms which simultaneously contribute to the electrical conductivity of the material. The former mechanism is associated with the potential grain-to-grain barriers. The latter mechanism involves the barriers created by intragrain structural defects. The results of the SPM study shed new light on the origin of the colossal dielectric constant in CCTO.

Biofilms can damage implants and are difficult to treat. Here, we assessed the performance of a tripeptide that self-assembles into an antifouling coating over a broad range of shear conditions that are relevant to biomedical applications. Adhesion assays were performed using a parallel plate flow chamber. The results show that the coating can reduce Escherichia coli adhesion up to 70% when compared with glass. At a shear rate of 15/s, typical for urinary catheters, the coating reduced the adhesion by more than 50%. These findings suggest critical features that should be considered when developing surfaces for biomedical purposes.

There is an increasing interest in the generation of well-defined nanoparticles (NPs) not only because of their size-related particular properties, but also because they are promising building blocks for more complex materials in nanotechnology.

Here, we will shortly introduce the gas-phase synthesis technology that has evolved rapidly in the last years and allows the fabrication of complex NPs with controllable and tuneable chemical composition and structure while keeping very good control over the size distribution. We will also address some limitations of the technology (stability over time, production yield, etc.) and discuss possible solutions.

In in vitro separate compartment model of neuronal cells and extracellular iron oxide nanoparticles (IONs)–amyloid complexes, a traversing proton-induced Coulomb nanoradiator effect (CNR) was found to break up the ION–amyloid fibrils and to induce redox changes in the IONs. We found that the CNR effect caused the conversion of redox-active iron (II) into redox-inactive iron (III) as well as the disruption of the ION–amyloid fibrils without significantly damaging normal neuronal cells. Our observations suggest a non-invasive redox inactivation and β-amyloidolyis-based therapy of neurotoxic Aβ plaque involving a traversing proton Coulomb nanochelator that would not substantially impact normal neuronal cells.

Using time-resolved laser-scanning confocal microscopy and ultrafast optical pump/THz probe spectroscopy, we measure photoluminescence (PL) and THz-conductivity in perovskite micro-crystals and films. PL quenching and lifetime variations occur from local heterogeneity. Ultrafast THz-spectra measure sharp quantum transitions from excitonic Rydberg states, providing weakly bound excitons with a binding energy of ~13.5 meV at low temperatures. Ab-initio electronic structure calculations give a direct band gap of 1.64 eV, a dielectric constant of ~18, heavy electrons, and light holes, resulting in weakly bound excitons, consistent with the binding energies from the experiment. The complementary spectroscopy and simulations reveal fundamental insights into perovskite light-matter interactions.

Here, we report thiol-free thermal-injection synthesis of chalcopyrite (CuFeS2) nanocrystals (NCs) using iron (II) bromide (FeBr2), copper (II) acetaylacetonate (Cu(acac)2), and elemental sulfur (S). Controlled reaction temperature and growth time yield stable and phase-pure ternary CuFeS2 NCs exhibiting tetragonal crystal structure. With increasing growth time from 1 to 30 min, absorption peak slightly red shifts from 465 to 490 nm. Based on spectroscopic ellipsometry analysis, three electronic transitions at 0.652, 1.54, and 2.29 eV were found for CuFeS2 NC film. Also, CuFeS2 NC thin films are incorporated as hole transport layers in cadmium telluride solar cells reaching an efficiency of ~12%.

The development of advanced fuel fabrication technologies is important for developing accident-tolerant fuels and engineering fuels for safer and more effective nuclear energy systems. In this work, commercial-size uranium dioxide (UO2) fuel pellets with a theoretical density of 95% were consolidated by spark plasma sintering (SPS) at 1600°C for 5 min. Systematic investigations suggest uniform densification and stoichiometric UO2 with an ideal fluorite structure across the commercial-size fuel pellet, but with a distributed grain structure because of non-uniform distribution of temperature during sintering. This work demonstrates a great potential of using SPS for fabricating nuclear fuels at a cost-effective manner.