What do fiber optics, superconductors, memory wire, polymers, solid state devices, ferrofluid, rare earth magnets, carbon-based electroacoustic devices, and photonic crystals have in common? They are all products of materials science research. Many of these advances play an important role in improving daily life; all are capable of enhancing the teaching of physics. This paper will address how topics from materials science can be used to ignite student interest by providing the basis for exciting hands-on activities.

Silicon has been used as one of the primary substrates for micro-machined intra-cortical neural implants (INI). The presence of various ions in the extracellular environment combined with cellular biological activity establishes a harsh, corrosive environment in the brain for INI, and as such, a long-term implant’s construction materials must be able to resist these environments. We have examined if environmental components could contribute to changes in the material, which in turn may be a contributing factor to the decreased long-term reliability in INI optimal neural recordings, which have prevented clinical use these devices for the last 4 decades. We tested silicon in artificial cerebrospinal fluid (ACSF), Dulbecco's modified eagle medium (DMEM), and H4 cells cultured within DMEM for 96 hours at 37°C as three various physiological environments to investigate the material degradation. We have observed that Si samples immersed in only DMEM and ACSF showed very minor surface alterations. However, Si samples cultured with H4 cells exhibited a large change in surface roughness from 0.24±0.04 nm to 4.85 nm. The scanning electron microscope (SEM) micrographs showed the presence of pyramid shaped pits. Further characterization with atomic force microscope (AFM) verified this result and quantified the severe changes in the surface roughness of these samples. At this initial stage of the investigation, we are endeavoring to identify the cause of these changes to the Si surface, but based on our observations, we believe that the increased corrosion could be result of chemical products released into the surrounding environment by the cells.

We developed a rapidly-gelling chitosan sponge crosslinked with Guanosine 5'-Diphosphate (GDP). GDP has not been previously explored as an anionic crosslinker, and it was used in this application since the nucleoside guanosine has been shown to improve remyelination in situ, and thus its presence in the sponge composition was hypothesized to induce Oligodendrocyte Progenitor Cells' (OPC) differentiation. In addition to the chemical composition tailored to target OPCs, the developed chitosan sponge possesses a wide range of desirable physicochemical properties such as: rapid gelation, high porosity with interconnected pores, moduli of elasticity resembling that of soft tissue and cytocompatibility with many cell types. Moreover, protein encapsulation into the sponges was possible with high encapsulation efficiencies (e.g. BMP-7 and NT-3). In this study, BDNF was encapsulated in the chitosan sponges with an encapsulation efficiency greater than 80% and a sustained release over a 16-day period was achieved. We demonstrate here for the first time, the attachment of human fetal OPCs to the sponges and their differentiation after 12 days of culture. Overall, this newly-introduced injectable sponge is a promising therapeutic modality that can be used to enhance remyelination post-spinal cord injuries.

The kinetic performance of metallocene type catalysts as well as their instantaneous activity is determined on line by two independent methods in the semi-batch polymerization of ethylene via metallocenes. On the basis of first-principles, both methods are described and guidelines for their implementation at a laboratory scale reactor are offered. Polymerization tests were conducted with two heterogenized metallocene catalysts showing that the direct method (based on ethylene flow measurement) and also the calorimetric method (based on energy balances) reported equivalent high quality information. The calorimetric method here developed can be readily used by the chemical practitioner as the notions and tools required for its implantation are easily grasped. It is noted that the calorimetric method has the advantage of requiring a low cost instrumentation (only thermocouples) whereas the direct method needs a relatively more sophisticated equipment (mass flow meter).

In this work we present new results on the morphological and microstructural properties of GaAs-AlxGa1-xAs (x≈0.24) core-shell nanowires (NWs) epitaxially grown on (111)B-GaAs substrates by Au-catalyst assisted metalorganic vapor phase epitaxy (MOVPE). Optimized growth conditions allowed us to fabricate highly-dense arrays of vertically-aligned (i.e., along the <111> crystallographic orientation) NWs. The NW arrays were investigated by Helium Ion microscopy (HeIM) and X-ray double- and triple-axis measurements and reciprocal space mapping (RSM). We demonstrate that these techniques can be employed in order to correlate some intrinsically local morphological information with statistically relevant (i.e. averaged over millions-to-billions of NWs) data on the NW structural properties.

We report fluorescence correlation spectroscopy (FCS) measurements of the translational diffusion of two fluorescent nanoprobes, rhodamine (R6G) and carboxytetramethylrhodamine (TAMRA), embedded in poly(vinyl alcohol) (PVA) solutions and gels. The diffusion coefficient was measured as a function of the PVA concentration and pH. Furthermore, we designed and built an optical chamber to determine the diffusion coefficient of the nanoprobes within the PVA solutions and gels subjected to controlled dehydration. We find that 1) lowering pH causes an apparent slowing down of the diffusion of the nanoprobes, 2) increase of PVA concentration and crosslink density also induce slowing down of both nanoprobes, and 3) dehydration induces systematic decrease of the diffusion of TAMRA in both solutions and gels. Taken together, these results demonstrate that transient physical interactions between the nanoprobes and the PVA linear polymers have a significant effect upon nanoprobe diffusion.

Around the radioactive waste repository, the pH of the groundwater greatly changes from 8 to 13 and the groundwater contains a relatively large quantity of calcium (Ca) and sodium (Na) ions due to cementitious materials used for the construction of the geological disposal system. Under such conditions, the deposition behavior of silicic acid is one of the key factors for the migration assessment of radionuclides. The deposition and precipitation of silicic acid with the change of pH and coexisting ions may contribute to the clogging in flow paths, which is expected as the retardation effect of radionuclides. Thus, this study focused on the deposition behavior of silicic acid under the condition of relatively high Ca or Na concentration.

In the experiments, Na2SiO3 solution (250 ml, 14 mM, pH>10, 298 K) was prepared in a polyethylene vessel containing amorphous silica powder (0.5 g) as the solid phase. Then, a buffer solution (to adjust to 8 in pH), HNO3, and Ca(NO3)2 as Ca ions or NaCl as Na ions were sequentially added. Such a silicic acid solution becomes supersaturated, gradually forming colloidal silicic-acid and/or the deposit on the solid surface. In this study, the both concentrations of soluble and colloidal silicic-acid were monitored over a 40-day period. As a result, the deposition rate of silicic acid decreased with up to 5 mM in Ca ions. Besides, Na ions with up to 0.1 M slightly increased the deposition rate. Under the conditions of [Na+]>0.1 M or [Ca2+]>5 mM, the supersaturated silicic acid immediately deposited. These suggest that Na or Ca ions strongly affect the deposition behavior of supersaturated silicic-acid, depending on the surface alteration of solid phase, the change of zeta potential and the decrease of water-activity due to the addition of electrolytes (coexisting ions).

La Blanca and Chilonche are two of the many Mayan settlements located on the lower reaches of the Mopan river (Department of Petén, Guatemala). The archaeological work conducted by La Blanca Project (University of Valencia, Spain) over the last ten years has revealed the rich polychrome of the monumental architecture of these sites, where the remains of ancient mural paintings are of the highest quality.

In order to ascertain the materials and techniques used by painters at each site throughout the Classic period, our research team has recently conducted an analytical study with a multi-technique approach based on the combination of several non destructive and micro-destructive instrumental techniques, namely, light microscopy (LM), scanning electron microscopy-X-ray microanalysis (SEM/EDX), transmission electron microscopy (TEM), voltammetry of microparticles (VMP), X-ray microdiffraction (mXRD), X-ray diffraction (XRD), UVeVis spectrophotometry, FTIR spectroscopy and gas chromatographyemass spectrometry (GCeMS). These instrumental techniques provide reliable and complementary data, such as elemental and mineralogical composition, the identification of functional groups as well as specialization studies of electroactive species.

This paper presents the results obtained at the Laboratories for the Analysis of Works of Art at the University of Valencia (Spain) and the Polytechnic University of Valencia (Spain) after chemically comparing the pigments and mural painting techniques of both Maya archaeological sites.

Cell aging and state-of-health (SOH) estimation is widely acknowledged as a challenge in state-of-the-art battery management systems deployed today. Towards addressing this issue, gas evolution monitoring from side reactions using embedded sensors was investigated as a parameter of interest for SOH. Li-ion battery cells with a Mn-rich chemistry were subjected to overcharge experiments. Two cells were repeatedly overcharged and the evolution of gaseous CO2 was measured using fiber optic colorimetric sensors, which were incorporated and sealed into the side pouch of the battery pouch cells. A ratiometric read-out principle has been employed for the optical measurements. Initial results indicate a non-reversible gas evolution inside the battery cells during overcharge, wherein the onset of gas evolution is delayed in time relative to the overcharge condition. An increase in the sensing signal can be observed over a time span of 40 – 50 minutes during each overcharge cycle. This investigation provides real-time information on the dynamics of gas evolution in Li-ion pouch cells during overcharge experiments and allows for an early detection of potentially hazardous cell states.

Hydroxyapatite (HAP) is a biocompatible bio-ceramic whose structure and composition is similar to bone. However, its lack of strength and toughness have seriously hampered its applications as a bone graft substitute material. Attempts have been made to overcome these mechanical properties deficiencies by combining HAP bioceramic material with absorbable polymers in order to improve its mechanical properties. However, poor interfacial bonding between the HAP and the polymers has limited the benefits of such biocomposite structures. At the other end of the biomaterials spectrum is collagen, which constitutes the most abundant proteins in the body and exhibits properties such as biodegradability, bioadsorbability with low antigenicity, high affinity to water, and the ability to interact with cells through integrin recognition. These favorable properties renders collagen as a natural candidate for the modification and compatibilization of the polymer-HAP biocomposite. In this study, we developed a novel approach to the synthesis of a potential bone graft material, where the HAP moiety acts not only as a bioceramic filler, but also constitutes the initiator surface that promotes the in-situ polymerization of the adsorbable polymer of choice. The synthesis of poly(D,L-lactide-co-glycolide) (PLGA) polymer was catalyzed by nano-hydroxyapatite (nHAP) particles and upon reaction completion, the biocomposite material was tethered with collagen. The synthesis was monitored by 1H NMR and FTIR spectroscopies and the products after each step were characterized by thermal analysis to probe both thermal stability, morphological integrity and mechanical properties.

Praseodymium doped CaFe2As2 (122 structure) and CaFeAs2 (112 structure) are characterized by modulated Low Magnetic Field Microwave Absorption (LFMA) spectroscopy. In both (Pr,Ca)122 and (Pr,Ca)112 structures, a strong hysteretic LFMA is found, with a T c H of ∼30 K and ∼26 K, respectively. However, in (Pr,Ca)122, measurements also show an unusual Narrow Peak (NP) LFMA signal appearing at higher temperatures, above the lower T c H superconducting state until a T c NP of 49 K. We associate this NP LFMA with interfacial superconductivity, which has been found previously by highly anisotropic magnetization measurements. Furthermore, the absence of NP in (Pr,Ca)112 correlates with the absence of an interfacial phase. These results give useful information about the microwave signature of interfacial superconductivity present in the (Pr,Ca)122 system, and may form a roadmap towards a stabilized high temperature superconducting phase in pnictides.

A ferroelectric crystal with charge-free surface conditions contains polarized domains which can form a flux closure with zero net polarization. In the presence of an external electric field, the flux closure in a two-dimensional continuum reorients its spontaneous polarization to align with the field. Based on this concept of ferroelectric switching coupled with mechanical straining, we demonstrate the working principle of a ferroelectric nano-actuator. The behavior of the actuator is explored under the action of electro-mechanical loading and its mechanism is simulated with a 2D phase-field model. The design of nano-actuator is modified to achieve greater actuation displacements by bending a thin device.

Twenty-five years ago the desktop computer started becoming ubiquitous in the scientific lab. Researchers were delighted with its ability to both control instrumentation and acquire data on a single system, but they were not completely satisfied. There were often gaps in knowledge that they thought might be gained if they just had more data and they could get the data faster. Computer technology has evolved in keeping with Moore’s Law meeting those desires; however those improvements have of late become both a boon and bane for researchers. Computers are now capable of producing high speed data streams containing terabytes of information; capabilities that evolved faster than envisioned last century. Software to handle large scientific data sets has not kept up. How much information might be lost through accidental mismanagement or how many discoveries are missed through data overload are now vital questions. An important new task in most scientific disciplines involves developing methods to address those issues and to create the software that can handle large data sets with an eye towards scalability. This software must create archived, indexed, and searchable data from heterogeneous instrumentation for the implementation of a strong data-driven materials development strategy. At the National Center for Photovoltaics in the National Renewable Energy Laboratory, we began development a few years ago on a Laboratory Information Management System (LIMS) designed to handle lab-wide scientific data acquisition, management, processing and mining needs for physics and materials science data, and with a specific focus towards future scalability for new equipment or research focuses. We will present the decisions, processes, and problems we went through while building our LIMS system for materials research, its current operational state and our steps for future development.

γ-U alloys with Mo or Zr are more resistant to hydrogen than U metal. High pressures of H are needed to produce hydrides. Amorphous structure of UH3Mox can be represented as the cubic structure of β-UH3 type with grain size around 1 nm. UH3Zrx are formed in the cubic α-UH3 type of structure. All the hydrides are ferromagnets, with magnetic parameters (magnetic moments, Curie temperature) exceeding those of β-UH3 (0.9 μB/U, 165-170 K). It is deduced that α-UH3 has magnetic properties very similar to β-UH3, despite rather different U-U spacing.

Duplex stainless steels (DSS) have good mechanical and corrosion resistance properties which allow their application in very aggressive environments. However, their aging at 600–1000 °C causes the precipitation of dangerous intermetallic phases, resulting in serious detrimental effects on their interesting properties. These secondary phases are structural discontinuities which act as preferential cracks initiation sites and their negative effect is especially highlighted on toughness. For these reasons, many standards related to the manufacturing of DSS require the microstructure of these steels "free from intermetallics". In this paper, the effect of isothermal heat treatments on the impact toughness in two Duplex steels (SAF 2205 and Zeron®100) has been investigated, in order to study the influence of different amount of secondary phases on the toughness response.

We examined the potential application of CuIn1-xGaxSe1-ySy (CIGS) film for visible light image sensors. CIGS chalcopyrite semiconductors, which are representative of high efficiency thin film solar cells, have both a high absorption coefficient and high quantum efficiency. However, their dark current is too high for image sensors. In this study, we applied gallium oxide (Ga2O3) as a hole-blocking layer for CIGS thin film to reduce the dark current. The dark current of this hetero-junction was 10-9 A/cm2 at less than 7 V. Moreover, an avalanche multiplication phenomenon was observed at an applied voltage of over 8 V. However, this structure had sensitivity only in the ultraviolet light region due to the much lower carrier density of the Ga2O3 layer. We therefore used a tin-doped Ga2O3 (Ga2O3:Sn) layer deposited by pulsed laser deposition (PLD) for the n-type layer to increase the carrier density. The sensitivity of the visible region was observed in the Ga2O3:Sn/CIGS hetero-junction. We also investigated the influence of the laser frequency of the PLD on the transmittance of Ga2O3:Sn and the quantum efficiency of this hetero-junction. Ga2O3:Sn film deposited at a 0.1-Hz laser repetition rate had higher transmittance than at a 10-Hz repetition rate. The Ga2O3:Sn/CIGS hetero-junction also had a higher quantum efficiency with the lower rate (50%) than with the higher rate (30%).

The kinetic/thermodynamic stabilization recent results of grain growth in nanomaterials (NMs)-based metals, alloys, and compounds are generalized. Due to their large share of interfaces which can act as the sinks for radiation defects, NMs show improved irradiation resistance such as the resistance to amorphization, hardening and swelling. Radiation defects will tend also to the nanostructure annihilation and transformation into amorphous state. Some unsolved problems are emphasized.

Periodically ordered nanohetero inorganic structures offer great promise due to their unique electric, ionic, magnetic, and photonic properties. Many studies have focused on the formation of periodically ordered nano-hetero inorganic structures through layer-by-layer adsorption, sputtering, and self-assembly methods. However, the construction of three-dimensional periodically ordered nanohetero inorganic structures with desired sizes and morphologies remains a great challenge. We present a simple method for producing three-dimensional periodically ordered inorganic nanoheterostructures with controlled shape and size by replicating self-assembled block copolymers (BCPs) containing precursors of metals and metal oxides. Precursors were dissolved with BCPs in a solvent. Upon evaporation of the solvent, each precursor was selectively introduced into a separate polymer block. Application of an external magnetic field (10 T) to the BCP-precursor composites resulted in a phase transition of from spheres to hexagonal cylinders. Subsequent pyrolytic removal of the BCPs produced periodically ordered nanoheterostructures that were structural replicates of the precursor–BCP composites. Self-assembled nano-hetero inorganic structures of nanoparticles, nanorods and layers in a matrix were produced. The morphology and domain size can be tailored by controlling the molecular weight and relative block length of block copolymers. The controlled size and morphology of the inorganic nanoheterostructures demonstrate the method’s utility for producing highly functional materials.

Surface plasmon polaritons (SPPs), which are coupled excitations of electrons bound to a metal-dielectric interface, show great potential for application in future nanoscale photonic systems due to the strong field confinement at the nanoscale, intensive local field enhancement, and interplay between strongly localized and propagating SPPs. The fabrication of sufficiently smooth metal surface with nanoscale feature size is crucial for SPPs to have practical applications. A template stripping (ST) method combined with PMMA as a template was successfully developed to create extraordinarily smooth metal nanostructures with a desirable feature size and morphology for plasmonics and metamaterials. The advantages of this method, including the high resolution, precipitous top-to bottom profile with a high aspect ratio, and three-dimensional characteristics, make it very suitable for the fabrication of plasmonic structures. By using this ST method, boxing ring-shaped nanocavities have been fabricated and the confined modes of surface plasmon polaritons in these nanocavities have been investigated and imaged by using cathodoluminescence (CL) spectroscopy, which has been turned out to be a powerful means to characterize the resonant SPPs modes confined in metal nanocavities [1∼5] . The mode of the out-of-plane field components of surface plasmon polaritons dominates the experimental mode patterns, indicating that the electron beam locally excites the out-of-plane field component of surface plasmon polaritons. Quality factors can be directly acquired from the spectra induced by the ultrasmooth surface of the cavity and the high reflectivity of the silver (Ag) reflectors. Because of its three-dimensional confined characteristics and the omnidirectional reflectors, the nanocavity exhibits a small modal volume, small total volume, rich resonant modes, and flexibility in mode control. Numerous applications, such as plasmonic filter, nanolaser, and efficient light-emitting devices, can be expected to arise from these developments.