A superparamagnetic Janus nanocomposite (SJNC) of polystyrene/Fe3O4@SiO2 was designed and developed with dual surface bearing functional groups for medical diagnosis and treatment. Folic acid (FA) and doxorubicin (DOX) were conjugated stepwise to the surfaces. SJNCs were found to enable simultaneous cell-targeted drug delivery via pH-responsive release mechanism.

We focused on the presence of water absorbed in the grain boundary of a polycrystalline transition metal oxide (TMO) film in an EL/poly-TMO/EL structure. The effect of supplying water to resistive random access memories (ReRAMs) of Pt/NiO/Pt structure on switching voltages and data retention characteristics was investigated. As a result, switching voltages were decreased by supplying water and reset switching was confirmed to be strongly induced by supplying water even at room temperature without applying voltage. These results suggest that water enhances resistive switching effect by providing reducing species and oxidizing species respectively such as H+ and OH-.

We describe recent results in quantum materials through the use of a new tool: the x-ray free electron laser. We briefly describe the instrument and x-ray source capabilities and then discuss how this tool can bring new insights into materials with strong-electron correlations by ultrafast x-ray scattering from electronic structure.

Spin-polarized first-principles calculations have been conducted to study the electronic structures and magnetic properties of O and S functionalized zigzag aluminium nitride (AlN) nanoribbons. Chemical functionalization with O atoms at the edges strengthens the half-metallic properties of the AlN by adding new electronic states at the Fermi level for one spin-channel and widening the gap of the other. On the contrary, edge-termination with S atoms renders the AlN ribbon a semiconductor. Peierls instabilities towards the dimerization and trimerization of the doping atoms were observed.

Polyaniline–Zinc oxide nano-composite material was prepared by chemical polymerization of aniline with ZnO nano-particles doping. Surface Pressure-Area (π-A) isotherms of Polyaniline (PANi) and Polyaniline–Zinc oxide nano-composite shows phase transformations of monolayer during compression process. Multiple isotherms indicate that the monolayer of the composite material can retain its configuration during compression-expansion cycles. The structural, topographical and electrical properties of these deposited Langmuir Blodgett films were studied and characterized by UV-Visible spectroscopy (UV), Atomic force microscopy (AFM), Conductive Atomic force microscopy (C-AFM) respectively. For detailed investigations of the LB film properties, Conductive AFM is used to measure the I-V relationship of a surface of Langmuir Blodgett (LB) films of Polyaniline and Polyaniline–Zinc oxide nano-composite. The contact size of the AFM cantilever tip can be as small as a few nanometers, so, the local variation of the electrical property, which is unseen in the macroscopic level, can be observed by the I-V curve. A current ranging up to 3 nA and 20 nA have been observed in the case of PANi and PANi-ZnO nano-composite LB film, respectively. Conductive data images of the ITO substrate, PANi and PANi-ZnO nano-composite LB film on the ITO substrate obtained with an applied bias voltage of 4V showed that the distribution of current on the whole surface is almost uniform and very less inhomogeneities have been observed in the surface conductance of the PANi and PANi-ZnO nano-composite LB film.

A multi-block associative polyelectrolyte based on poly(methacrylic acid-ra-styrene) [MAA-S] and poly(octadecyl methacrylate) [ODMA] was synthesized through stepwise nitroxide-mediated solution polymerizations. The obtained polymer has a heptablock copolymer structure, alternating MAA-S as hydrophilic blocks (theoretical degree of polymerization [DPT] of 250), and ODMA as hydrophobic blocks (DPT = 15). Rheological properties, in the linear-response regime, of aqueous solutions (polymer content = 1.5 wt.%) were studied as a function of the amount of blocks on the polymer using steady-shear and creep-compliance experiments. Rheological experiments demonstrate that the viscoelastic behavior of the polymer bearing an ODMA block in terminal position greatly differs from that of the polymer with MAA-S block terminations. The former behaves as a newtonian fluid on a wider range of shear rates than the latter, which exhibit a shear-thinning behavior, even at low shear rates, independently of the molecular weight and number of blocks.

In studying large scale graphene structures it is necessary to consider the grain boundaries between the many single-crystal domains. The disruption of the crystallographic structure has consequences for both the electronic and transport properties. Although there has been much interest in this area in recent years, the size of system makes it difficult for ab initio methods to be applied to large structures and tight-binding models have provided some interesting results [1]. The semi-empirical Extended Hückel Theory (EHT) has advantage of being able to take account of charge reordering and to study very large systems. We have already applied this approach to study electrical transport across organic molecules and carbon nanoribbons. In this paper, we report on the results of EHT self-consistent calculations carried out to investigate the effect of grain boundaries on both the electronic structure and the electrical transport.

Calcium sulfoaluminate (CSA) cements are being developed using a novel processing method having as its objective lowering specific CO2 emissions by ∼50% relative to a Portland cement benchmark. We need to be able to measure the properties of the products. Porosity and permeability measurements help define the engineering properties but their quantification is influenced by the choice of experimental protocols. In the present study we used ordinary Portland cement (PC) paste as a benchmark and hydrated ye’elimite, which is a main component of CSA cements, to understand its pore structure. We report on the use of synchrotron-sourced radiation for µCT (Computerized Tomography) and 3D image re-construction of the internal micro-pore structure of PC and ye’elimite-gypsum pastes. As a comparison, porosity and permeability measurements were traditionally obtained using Mercury Intrusion Porosimetry (MIP). The Mori-Tanaka method and the polynomial statistical model were used to analyze the effects of different 3-D micro-pore structures on mechanical properties. The results show that e micro-pore structures differ considerably between PC and ye’elimite pastes and their bulk modulus is significantly affected by the shapes of their micro-pore structures.

A flow-through experimental reactor has been designed in order to perform studies at both high pressure and high temperature conditions. A chromatographic pump is used to impulse the leachant throughout the reactor in order to work at very low flows but high pressures. Therefore, high surface solid to volume leachant ratios, similar to the ones predicted in the final repository, can be obtained. The reactor allows working at different atmospheres at pressures up to 50 bars. The temperature inside the reactor can be set using a jacket.

Using this new reactor the evolution of uranium concentrations released from an UO2 sample was studied at different conditions.

The results show that at hydrogen pressures between 5 and 7 bars, hydrogen peroxide does not seem to significantly oxidize the uranium (IV) oxide. Uranium concentrations in those experiments remain between 10-8 mol·l-1 and 10-9 mol·l-1.

In this paper we report on a systematic study of Cu thin film dewetting by the monitoring of the intensity of the infra-red emission from the film surface during Rapid Thermal Chemical Vapor Deposition of graphene. The time evolution of Cu coverage highlights three typical stages of dewetting which strongly depend not only on the temperature and film thickness, but also on the pressure and composition of the gas in chamber. Consequently, we demonstrate that the Cu surface can be effectively activated in films at temperatures lower than in foils and the process can be fully controlled by adjusting those parameters, in order to reach the optimal conditions for graphene growth.

This study aims at investigating the formation of nanofibers containing poly (vinylidene fluoride) (PVDF) and Fe3O4 nanoparticles using magnetic field assisted electrospinning. For this purpose, two Helmholtz coils were mounted on the electrospinning apparatus in order to create a uniform magnetic field. Different separations, angles and magnetic fields are being analyzed. Polymeric solutions containing PVDF, DMF and acetone with a concentration of 18 wt% were adopted (DMF to Acetone ratio of 3 to 1). Iron Oxide Nanopowder (Fe3O4, particle diameter of 20 nm to 30 nm) to PVDF ratios are 1:5, 1:10 and 1:15. The application of the electromagnetic field during fiber deposition results in better orientation of the polymer flow towards the grounded electrode and leads to smoother fibers with diameters in the range of hundreds of nanometers. Blisters, probably related to Fe3O4 agglomerates, were distributed on the surface of all samples of this study. A magnetic field response of the nanofibers with higher magnetic fields was clear observed. By adding more Fe3O4 to the polymeric solution the ferromagnetic response on thin films and nanofibers was improved. The analysis of circular capacitors revealed a full dielectric response.

Course viability requires dealing with issues of adequate class size, diversity of academic background and goals, English fluency, heavy content and more. To this end, for thirteen years a consortium of five Virginia universities, including an HBCU, has shared a first-year graduate course on materials characterization. The journey began with just classroom co-presence. The present state includes common-server availability of materials (presentation slides, background articles, e-books), of content-delivery lectures (“full flip”) and of recorded class sessions (all). The most significant current issue is making effective use of the extensive in-class discussion time now made available by flipping.

In this work, the synthesis of two amphiphilic π-conjugated compounds such as ferrocenylthioamide and ferrocenylselenoamide, with the general formula FcC=MNH(CH2)15CH3 with M = S or Se, are reported. The ferrocenyl group is a donor moiety forming a π-conjugated system with the amides of sulfur and selenium; both elements have also bioactivity with pharmacological interest. These two compounds formed Langmuir (L) monolayers at the air-water interface, which were characterized by isotherms of surface pressure versus molecular area (π-A) and compression/expansion cycles (hysteresis curves); Brewster angle microscopic images were also obtained. By using the Langmuir-Blodgett method molecular monolayers were transferred onto glass substrates. These nanostructures, in form of Langmuir-Blodgett (LB) films, were characterized through atomic force microscopy (AFM).

Systems with a single or several coupled electron spins are commonly described with the quantum approach while ferromagnetic domains with millions of coupled spins are classical systems. Large spin clusters and superparamagnetic nanoparticles contain hundreds of coupled electron spins, and are on the boundary between classical and quantum behavior. Electron magnetic resonance observed in ultra-fine iron oxide nanoparticles (∼ 5 nm size) reveals several features which are typical for paramagnetic spins and absent in macroscopic systems, including multiple quantum transitions observed at H0/n, where n = 2, 3, 4 and H0 is the field of the main resonance. In order to better understand the transition from quantum to classical behavior and magnetization dynamics at the nanoscale, we study the evolution of the EMR signal with increase of the particle size in suspensions of magnetite nanoparticles. The experimental data are compared with numerical simulations.

Interactions between biological cells and surrounding extracellular matrix (ECM) materials modulate many cell behaviors including adhesion and migration. One key example of this cellmatrix reciprocity is in the context of angiogenesis, the sprouting of new blood vessels from preexisting vasculature. Vascular endothelial cells (VECs) create and remodel the ECM during this process. In vivo, the surrounding fluid environment includes high concentrations of macromolecules, and is considered “crowded” in comparison to in vitro environments. Here, we quantified the amount and organization of collagen IV, a prominent ECM component of VECs, that was produced by these cells over four weeks in vitro in the presence or absence of macromolecular crowder (MMC) nanoparticles that approximated in vivo crowding. In the presence of MMCs, the amount and degree of alignment of collagen IV was greater. This ECM difference emerged within one week and was sustained for over four weeks. We explored the effect of initial cell density (cells/µm2) on this matrix production, to consider potential differences at a wound site versus an intact vessel. Moreover, we found the biophysical effect of MMCs to be unmodulated by secretions from an adjacent cell type in microvessels (pericytes). These results suggest that macromolecular crowding plays a direct role in remodeling the basement membrane, and that such crowding can be induced in vitro to more closely approximate the cell microenvironment.

Electric transport in disordered media is usually explained in terms of different transport regimes, such as SCLC (Space Charge Limited Current) or TCLC (Trap Charge Limited Current) regimes. These models lead to exponential dependencies of the current on voltage, e.g., quadratic for SCLC or higher order for TCLC, with transition regions between them where fitting is poor. Alternatively, a statistical distribution in space and energy of the disordered traps, e.g., Gaussian or exponential, allows explaining transport in disordered materials. In this work, we propose a modeling based on the density of states (DOS) function, fitted from normalized differential conductivity curves obtained from experimental current-voltage curves. In general a Gaussian function is used for low energies whereas one or more exponential functions are used for higher energies. The proposed model is used to reproduce experimental current-voltage curves of organic nanocomposites, with gold and silver nanoparticles within chitosan matrixes. A unique expression is obtained for a very accurate fitting the experimental current-voltage characteristics in the whole voltage range without transition regions.

Chemical and biological deterioration of surfaces of historic constructions is one of the main causes of destruction of cultural heritage buildings. Effective techniques are searched in order to control the biofilm development of cultural heritage without damaging the environment. Nanotechnology is an emerging option with several applications, including those for improving stability and corrosion resistance in surfaces. Production of nanomaterials from organic nature or green synthesis offers ecological advantages such as low environmental impact. This paper proposes the use of silver nanoparticles of biological synthesis as an alternative for control of microorganisms that cause biodeterioration. The present study highlights the effect of these nanoparticles in the inhibition of bacterial growth. These particles were produced by biological synthesis with Tecoma stans L. extracts. Their characterization included analysis UV / Vis spectroscopy, scanning electron microscopy (SEM) and particle size distribution.

Stretchable wires were printed on fabrics using an acrylic-based paste loaded with Ag flakes, and their fatigue properties examined. The electrical conductivity of the wires significantly decreased during a cyclic tensile test, because of a decrease in their elastic moduli (Mullins softening) as well as fatigue cracking. Because the electrical resistance and elastic moduli of the damaged samples were partially recovered by annealing at 100 °C, fatigue damage introduced to the wires was divided into reversible and irreversible components, where cracking is the irreversible damage. Although crack bridging by fibrils could occur during the fatigue test, no crack healing was observed during annealing. In contrast, fatigue damage from Mullins softening of the wires could be recovered during annealing. The recovery of electrical conductivity occurs mostly in the initial stage of rearrangement of polymer structure during annealing.

The altarpiece dedicated to San Antonio de Padua was made of wood assembled and self-supporting structure attached to the wall. It is a straight plant altarpiece designed to withstand sculptures. This master piece belongs to the a set of Baroque altarpieces preserved in the state of Campeche and is located in San Roque Church in the City of San Francisco de Campeche, Mexico. This altarpiece was decorated following the traditional technique of the seventeenth century in Mexico, a technique derived from Spain. According to literature sources we know that the strata are the wood, the imprimatura, the pictorial strata and metal sheets that make the golden color and corladuras. The characterization of the constituent materials was of great importance for the interpretation of the constructions system and manufacture of the decoration. The present study shows the results of analysis techniques such as optical microscopy, Particle Induce X Ray Emission (PIXE), and X Ray Florescence Spectroscopy (XRF) and interpretation of the different layers constituting the altarpiece of San Antonio.

The connection between the bi-polar hafnia-based resistive-RAM (RRAM) operational characteristics and dielectric structural properties is considered. Specifically, the atomic-level description of RRAM, which operations involve the repeatable rupture/recreation of a localized conductive path, reveals that its performance is determined by the outcome of the initial forming process defining the structural characteristics of the conductive filament and distribution of the oxygen ions released from the filament region. The post-forming ions spatial distribution in the cell is found to be linked to a degree of dielectric oxygen deficiency, which may either assist or suppress the resistive switching processes.