In last two decades, huge amount of research work has been contributed in the field of nanochemistry particularly for synthesis, characterization and applications of carbon nanotubes (CNTs). For synthesis of CNTs through chemical vapor deposition (CVD), supported metal catalyst is used preferentially. In view of that, SBA-16 supported nanoprticles of Iron, Fe/SBA-16, were prepared. To have Fe/SBA-16, adsorption of Fe nanoparticles on SBA-16 have been accomplished by reduction of ferrous ion on the surface of SBA-16. Afterwards, CNTs were synthesized by CVD using benzene as precursor over Fe/SBA-16 nanocatalyst. Synthesis of CNTs was carried out at 750°C with ambient pressure. Synthesized CNTs were functionalized by treating the them with a mixture of H2SO4/HNO3. As a result of this acidic treatment, carboxylic functional group was introduced on the surface of CNTs due to oxidation. As such prepared and functionalized CNTs were, further, used as filler in the synthesis of polymer nanocomposites of polypyrrol(PPY), matrix. These nanocomposites were prepared by in situ polymerization. Thus, electrical conductivity is measured for both types of polymer composites. On their comparison, important information regarding dispersion of CNT in the matrix are extracted.

Surface modified L@SiO 2 particles bearing covalently attached functional groups (L) have been tested as co-catalysts for H2 production from Formic Acid (FA) by the homogenous FeII/P(CH2CH2PPh 2)3 catalyst. The L@SiO 2 particles induce remarkable increase of catalytic H2 production i.e. by 710 %, when L=a basic functionality such as Imidazoles, or NH2-groups. This effect is attributed to a thermodynamic promotion of FA deprotonation facilitating coordination of HCOO- anion on the FeII atom of active catalyst during catalysis.

The molecular relaxations behavior of chitosan (CS) films in the wide frequency range of 0.1-3x109 Hz (by using three different impedance analyzers) have been investigated in the temperature range of -100C to 120°C using Dielectric Spectroscopy (DS). Additionally to the low frequency molecular relaxations such as α and β relaxations, for the first time, high frequency (1-3 GHz) relaxation process has been observed in the chitosan films. This relaxation exhibits Arrhenius-type dependence in the temperature range of -100 C to 54°C with negative activation energy -2.7 kJ/mol. At temperatures above 54°C, the activation energy changes from -2.7 kJ/mol to +4.4 kJ/mol. Upon cooling, the activation energy becomes negative again with a value of -1.2 kJ/mol. The bound water between chitosan molecules strongly modifies molecular motion and the relaxation spectrum, giving rise to a new relaxation at the frequency at ca. 1 GHz. In situ FTIR analysis has shown that this relaxation related to the changes in vibration of the –OH, NH and –CO functional groups.

Light-induced electron spin resonance (LESR) study of polymer solar cells has been performed to investigate accumulated hole carriers in these devices under device operation. We analyzed clear correlation between the number of accumulated holes in regioregular poly(3-hexylthiophene) (P3HT) evaluated by LESR and the deterioration of device performance (V oc, J sc) observed using the same device under simulated solar irradiation. The effects of hole accumulation with deep trapping levels formed in P3HT at the organic interfaces on the performance are examined by considering interfacial electric dipole layers and charge-carrier scattering by accumulated holes.

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.