In situ synthesis of Ag nanoparticles in polyvinylidene fluoride (PVDF) was investigated using different stabilizers such as 3-aminopropyltrimethoxysilane (APS) and 1-dodecanethiol (thiol). Although PVDF is a matrix, it also functions as a stabilizer. Results of UV-vis spectroscopy showed that when APS or PVDF was used, Ag nanoparticles were formed. Yet no formation occurred when thiol was used due to the complexation of Ag+ ions by thiol. Polar groups on stabilizers has an important effect on complexation process. APS, a nitrogen-based ligand, has hard base character inhibiting the complexation between Ag+ and APS. Consequently, Ag+ ions are reduced to Ag nanoparticles in N,N dimethyl formamide (DMF), which acts as a solvent and reducing agent. Transition Electron Microscopy (TEM) image showed a uniform distribution of spherical Ag nanoparticles in PVDF matrix in the presence of APS. The electrical properties of flexible nano-metal polymer were tested and the highest improvements in breakdown strength and energy density of 33 and 58 %, respectively were measured with 0.05 wt.% Ag content and APS as a stabilizer.

We demonstrate that the extrusion speed of thermoplastic urethane elastomer can modify its optical transmission by a factor of more than 100. Varying extrusion speed at constant temperature may tune optical properties along the axis of a filament, for example creating absorbent regions that are sensitive to length and diameter changes, surrounded by more transmissive segments that carry the sensor signal over long distances. Such waveguiding in a stretchable optical fiber requires a stretchable cladding with lower refractive index than the core. In experiments toward a rugged, stretchable fiber cladding, we investigated whether solvents could modify the outer structure of the filaments. Soaking the filaments in NMP (n-methyl-2-pyrrolidone), then stretching the filaments while the solvent dried, turned out to modify the filaments in a way that solvents alone did not, creating porosity and reducing the appearance of optical clarity.

We present a study of optical and electronic properties of solutions and films based on the fungi-derived pigment xylindein, extracted from decaying wood and processed without and with a simple purification step (“ethanol wash”). The “post-wash” xylindein solutions exhibited considerably lower absorption in the ultraviolet spectral range and dramatically reduced photoluminescence below 600 nm, due to removal of contaminants most likely to be fungal secondary metabolites. The “post-wash” xylindein-based films were characterized by two orders of magnitude higher charge carrier mobilities as compared to “pre-wash” samples. This underlines the importance of minimizing contaminants that disrupt the conductive xylindein network in xylindein-based electronic devices.

This paper reports the results of preparing alloy nanoparticles by mechanical grinding followed by filtration to sort the particles according to size. Although the long-term goal of this work is to prepare icosahedral quasicrystalline nanoparticles, the alloy used in this study is of Al65Cu25Fe15 composition and multi phases, under the assumption that the established procedure is applicable to future quasicrystalline nanoparticle fabrication. The obtained particle size and elemental information were investigated using scanning electron microscopy and energy dispersive x-ray spectroscopy. Problems with filter fragment fall-out and salt contamination were encountered and procedures to address the problems have been suggested and tested. The study is successful in obtaining alloy particles with reduced sizes.

In this study, a novel brick-like NiCo2O4 material was synthesized via a facile hydrothermal method. The as-prepared NiCo2O4 material possessed high porosity with the BET specific surface area of 58.33 m2/g, and its pore size distribution was in a range of 5-15 nm with a dominant pore diameter of 10.7 nm. The electrochemical performance of the NiCo2O4 was further investigated as anode material for lithium-ion battery. The NiCo2O4 anode possessed a high lithium storage capacity up to 2353.0 mAh/g at the current density of 100 mA/g. Even at the high rate of 1 A/g, a reversible capacity of ∼600 mAh/g was still retained, and an average discharge capacity of ∼1145 mAh/g could be recovered when the current density was reduced back to 150 mA/g. Due to the simple and cost-effective process, the NiCo2O4 bricks anode material shows great potential for further large-scale applications on the area of lithium-ion battery.

A computational study based on molecular dynamics simulation technique has been used to predict the mechanical and thermal behavior of carbon nanotube (CNT) reinforced natural rubber (NR) composites. A single-walled 5,5 armchair type CNT has been used for this purpose. In this study, a comparison has been made between pristine and functionalized CNTs. The functionalization groups used in this study were carboxylic (COOH), ester (COOCH3) and hydroxyl (OH). The studies show the improvement in elastic properties of developed composites in the presence of functionalization group. In addition, the effect of volume fraction and 1-25% addition of functionalization group has been studied. The obtained simulation results show the better load-transfer capacity in developed polymer system and improved elastic modulus. Thermal properties of developed composite systems were studied by non-equilibrium molecular dynamics method (NEMD). The addition of functionalized CNTs shows enhanced mechanical and thermal properties.

We have developed new flexible dye-sensitized solar cells (DSSCs) comprising organic dye (JH-1), cobalt redox electrolyte and hierarchically structured TiO2 (HS-TiO2) photoelectrode prepared using an electrostatic spray method. The performance of JH-1 sensitized flexible DSSC with a cobalt redox electrolyte was compared with those of N719-based DSSC and DSSC with I-/ I3- redox electrolyte. As a result, JH-1 sensitized flexible DSSC with [Co(Ⅲ/Ⅱ)(bpy-pz)3](PF6)3/2 redox system exhibited a high photocurrent density of 9.17 mA cm-2, an open circuit voltage of 0.953 V, a fill factor of 0.70, and a power conversion efficiency of 6.12% under 1 sun illumination (100 mW cm-2). The incident photon-to-current conversion efficiency was measured to explain the photocurrent generation difference by different dyes and electrolytes. The electron recombination lifetime of cells was measured by intensity-modulated photovoltage spectroscopy. Mass transport in DSSCs employing cobalt redox electrolytes was also investigated by the photocurrent transient measurements and electrochemical impedance spectroscopy (EIS) analysis.

Conducting polymers namely polyaniline (PANI), polypyrrole (PPy) and their copolymer poly(Aniline-co-Pyrrole)(PAPY) were prepared via in-situ polymerization process. The X-ray diffraction (XRD), infra-red (IR)and field emission-scanning electron microscopy (FESEM) studies confirm the formation of polyaniline, polypyrrole and their copolymer with aniline and pyrrole. The XRD pattern of copolymer displayed an amorphous structure as compared to polycrystalline homopolymers. FE-SEM results of Poly (Ani-co-Py) shows the existence of agglomerated spherical structured particles in the copolymer matrix, while the polyaniline and polypyrrole exhibit the porous tubular and spherical structures, respectively. Thermo gravimetric analysis (TGA) shows that the copolymer is more stable as compared to their homopolymers at higher temperature. Four probe resistivity (FPR) studies indicate that copolymer has the lower conductivity and act as a diode. Vector network analyzer (VNA) measurements observe a significant shielding effectiveness (SE) for all the conducting polymers.

The constant search for the improvement of the performance of materials of industrial application, evaluated under aspects of weight reduction, greater resistance, greater resistance to wear and better thermal stability, among others, associated with the search for the development of ecologically viable products, that convert the context of environmental degradation in preservation and sustainability, reflects the need to conduct research that results in new materials. The objective of this work is to obtain composites of the AA6061 aluminum alloy reinforced with different contents of coke coal blast-furnace slag by powder metallurgy. The processing of these materials was done by sieving, mixing and compacting powders of reinforced aluminum alloy with 5, 10 and 15% of blast-furnace slag. The cold uniaxial compaction was realized at a pressure of 500MPa. The obtained materials were sintered at 580°C for 3h under inert atmosphere. Unreinforced aluminum alloy samples were also produced. The characterization of the materials was realized by density and hardness measurements and three-point bending tests. The analysis of its microstructure was realized by scanning electron microscopy. As results, the composites presented a homogeneous distribution of the reinforcing particles and also a progressive improvement of the hardness and the bending strength with the increase of the slag content, producing an increase of 79% in hardness and 128% in flexural strength, when compared to the material without reinforcement obtained by the same process. Such results give the coke coal blast-furnace slag a new possibility of exploitation in the metal-mechanical sector, besides contributing with the environmental issue.

The emergence of 2D materials has led to increased attention on correlating the structural, optical, and optoelectronic properties of atomically thin transition metal chalcogenides like MoS2. We demonstrate the tunability of the photoluminescence (PL) properties of bulk MoS2 via implantation of Nb ions. Raman spectroscopy is used to confirm the p-type doping. The PL intensity of MoS2 is drastically enhanced by the adsorption of p-type dopants. X-ray photoelectron spectroscopy (XPS) is used to study the change of MoS2 structure post-implantation. Our results provide a new route for modulating the optical properties of two-dimensional semiconductors. The strong and stable PL from defect sites of MoS2 created by Nb ion implantation may have promising applications in optoelectronic devices.

We report on structural, magnetic, optical, and dielectric properties of rare earth (Er and Yb)-doped ZnO nanoparticles with Na-co-doping for charge compensation by sol-gel process. The effect of doping concentration on the structural and dielectric properties of ZnO has been studied under magnetic field and UV excitation. The magnetodielectric and photodielectric effects at room temperature of doped ZnO are discussed in the light of magnetic and optical properties of Er3+ and Yb3+ ions.

High-energy lithium-sulfur (Li-S) batteries still suffer from poor rate capability and short cycle life caused by the polysulfides shuttle and insulating nature of S (and the discharge product, Li2S). Selenium disulfide (SeS2), with a theoretical specific capacity of 1342 mAh g−1, is a promising cathode material as it has better conductivity compared to sulfur. The electrochemical reaction kinetics of CNFs-S/SeS2 composites (denoted as CNFs/S1-xSex, where x ≤ 0.1) are expected to be remarkably improved because of the better conductivity of SeS2 compared to sulfur. Here, a high-performance composite cathode material of CNFs/S1-xSex for novel Li-S batteries is reported. The CNFs/S1-xSex composites combine the higher conductivity and higher density of SeS2 with high specific capacity of sulfur. The CNFs/S1-xSex electrode shows good initial discharge capacity of ∼1050 mAh g−1 at 0.05 C rate with high mass loading of materials (∼6-7 mg cm−2 of composites) and > 97% initial coulombic efficiency. The CNFs/S1-xSex electrode shows more than 600 mAh g-1 specific capacity after 50 charge-discharge cycles at 0.5C rate, much higher compared to the CNFs/S cathodes.

In this study, Zoledronic acid (ZOL), a type of nitrogen containing bisphosphonate, was loaded on graphene oxide (GO) particles to increase the particle size of the drug-nano-carrier complex which reduces drug filtration by the kidney and consequently, increases drug circulation time and its tumor uptake. The conjugation between ZOL and GO occurs via π− π stacking and hydrogen bonding interactions, and therefore, the drug may be gradually released from GO in physiological conditions which eliminates the need to apply high doses of the drug. Loading and release profile of ZOL on GO particles were investigated by using UV-Vis spectroscopy. Samples with different concentrations of 0.025-1.25 mg/ml of ZOL were loaded on 0.2 mg/ml GO. UV analysis showed that the maximum loading happens at ZOL to GO ratio of 1:0.2. This loading was obtained when 1 mg/ml of ZOL was initially loaded on 0.2 mg/ml of GO nanoparticles. The drug and drug carrier complexes were characterized by UV-vis spectroscopy.

The present work has been carried out in order to investigate the sliding wear performance of a Ni-Cr based alloy, containing boron, carbon, silicon and iron, deposited onto a SAE 1045 steel substrate. The coatings were thermally sprayed by means of a High Velocity Oxy-Fuel system and post heat-treated for one hour at 760°C in an argon atmosphere. The relative sliding performance was evaluated under unlubricated dry conditions at different applied normal loads and sliding velocities, in order to analyze the influence of these parameters on the wear response. Test results are discussed and interpreted on the basis of both microstructural evaluations and mechanical properties measurements. The surface morphology and topography of the wear scars have been studied through of a Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) techniques. The results have shown an improved wear resistance of the coated steel samples as compared to the uncoated ones.

Unlike the conventional layer by layer growth ,three dimensional growth experiments of SiC single crystal by the Chemical Particle Deposition (CPD)method were carried out both on the polar and nonpolar plane of the SiC seed crystal. The comparison of the morphology of the grown crystals on both samples indicated that the electric field formed by the seed crystal strongly effected the diffusion of the supplied Si and C atoms and their compounds to grow the epitaxial crystal. In spite of the low ionicity of Si-C bonds, this remarkable effect of the electric field on the three dimensional crystal growth mechanism in the CPD method strongly suggested its contribution to the ordering of the stacked layers with its long working range, beyond the deformed boundary layers between the seed surface and the grown crystal.

The effects of La-substitution into SrTiO3 (STO) perovskite oxides on their phase structure, formation enthalpy and electrical conductivity have been investigated. La substitution in STO has been reported to show a significant enhancement in electronic conductivity in a wide-band-gap layered perovskite compound STO. Mixture of Lanthanum and Titanium oxide may lead to various phases including La2/3TiO3, La2Ti2O7 and La2TiO5. In this work, more than 50 structural models have been constructed by considering ionic state substituents, distance between substituents and their concentrations. We investigated the formation enthalpy, elastic properties and band gap by density functional theory (DFT) calculations. We have also investigated the effect of reducing environment on La2/3TiO3. The computed bulk modulus (∼2.4 % deviation) and band gap (∼12% deviation) of STO are in good agreement with the literature. Our results indicate that La substitution into STO could significantly reduce the band gap. Reduction in band gap is maximum when the substituents is present at low concentrations. Internal position of La substituents in STO affects the band gap marginally while energy remains almost same. Formation enthalpy of La2/3TiO3 from LaTiO3 is around 2 eV. La2/3TiO3 acts as band insulator (band gap = 2.8 eV). In reducing environment, the band gap of La2/3TiO3 significantly reduces. Sr substitution in La2/3TiO3 lower the band gap and formation enthalpy. La2Ti2O7 and La2TiO5 have higher band gap and lower bulk modulus than STO. Sr substitution is not feasible in La2Ti2O7 and La2TiO5.

Organic light-emitting diodes (OLEDs) have attracted huge concern because of their intrinsic characteristics and ability to reach the pinnacle in the field of high-quality flat-panel displays and energy-efficient solid-state lighting. High-efficiency is always a key crux for OLED devices being energy-saving and longer life-span. OLEDs have encountered enormous difficulties in meeting the requirements for large-sized devices due to a major limitation in vacuum thermal evaporation technology. In multilayered OLED devices, the characteristics of the charge injection/transport layer is a crucial factor for the operating-voltage, power-efficiency and stability of the device. Transition metal oxides have shown great potential owing to their wide range of possible energy level alignments, balanced charge injection, and improvement of carrier mobilities. In this study, we report a solution-processed blend V2O5-PEDOT:PSS hole-injection/hole-transport layer (HIL/HTL) for efficient orange phosphorescent OLEDs. The electroluminescent characteristics of blend V2O5-PEDOT:PSS based devices were studied with the structure ITO/V2O5-PEDOT:PSS/CBP:Ir(2-phq)3/TPBi/LiF/Al. The V2O5-PEDOT:PSS based OLEDs displayed relatively higher device performance and low roll-off than that of the counter PEDOT:PSS device in terms of a maximum luminance of 17,670 cd m-2, power efficiency of 19.4 lm W-1, external quantum efficiency of 8.7%, and more importantly, low turn-on voltage. These results demonstrate an alternative approach based on metal oxide/organic blend HIL/HTL as a substitute of PEDOT:PSS for high-efficiency solution process OLEDs.

Honeycomb structures, owing to their microstructural periodicity, exhibit unique and complex acoustic properties. Tuning their acoustic properties typically involves either changing their topology or porosity. The former route can lead to topologies that may not be readily amenable for large-scale production, while the latter could negatively affect the honeycombs’ weight. An ideal approach for tailoring the acoustic behavior of honeycombs should neither affect their porosity nor should they require customized and expensive fabrication methods. In this work, a novel honeycomb design that alters the microstructural topological features in a relatively simple way, while preserving the porosity of the honeycombs, to tune the acoustic properties of the honeycombs is proposed. The proposed honeycomb can be fabricated using the traditional approach employed to mass produce honeycomb structures; that is by bonding identical corrugated sheets with two periodic thicknesses. The acoustic behavior of the proposed honeycomb in terms of dispersion and phase velocities is analyzed using the finite element method. Simulation results demonstrate the potential of the designed honeycomb to exhibit tailored acoustic behavior at a constant porosity or mass. For example, it is demonstrated that the phase velocities of asymmetric and symmetric waves traversing the proposed honeycomb of aluminum with 90% porosity can be tuned by 30% and 17%, respectively.

Carbon nanotubes (CNTs) possess impressive properties along with low density. Integration of CNTs in the form of fabrics or other preformed assemblies simplifies their handling and allows for the higher CNT content needed to better leverage their properties in multifunctional structures. Here we describe production of non-woven CNT-polyurethane fabrics made from industrial-grade CNTs via a one-step filtration method. Individual sheets were scaled to 30 cm x 30 cm size and subsequently used to fabricate thicker composites, including via lamination with itself to produce simple panels and with other materials to further tailor the nanocomposite properties and address several example applications including electrical heating, fire resistance, electromagnetic shielding, and a skin for stretchable morphing structures.