Colloidal sol-gel is a common method used for the preparation of stable and homogeneous nanoparticulate sols. In this work, TiO2 and Er3+ doped-TiO2 sols (1, 2 and 3 mole % Er3+) have been prepared. The peptization time, viscosity and isoelectric point increase at higher Er3+ concentration indicating that erbium (III) delays the peptization process, increases the viscosity and adsorbs onto the surface of the TiO2 nanoparticles. When the sols of TiO2 are doped with Er3+ lower values of the band gap are obtained. After drying, in all cases, anatase was obtained as major phase although traces of brookite are also detected. The microstructure was observed by TEM and shows direct evidence that the xerogels are polycrystalline.

Roll-to-roll manufacturing holds the potential to rapidly and cheaply produce electronic devices in a flexible format as well as to effectively scale up production of emerging nanotechnologies. Developing scalable techniques for the efficient and effective use of solution-processed functional material is a significant factor in realizing the potential of roll-to-roll manufacturing. We present a novel inkjet deposition process developed to rapidly deposit arrays of micron-wide lines of silver nanoparticles for use as an optically transparent and electrically conducting film. The technique involves jetting a controlled number of space-overlapped drops of a dilute nanoparticle silver ink onto a substrate to form a long stable ink rivulet with two parallel and pinned edges. Subsequently, nanoparticles deposit preferentially at the two parallel rivulet edges due to edge-enhanced evaporation of the solvent. The final result is a twin-deposit of parallel continuous nanoparticle lines, each with a characteristic width less than 5μm and height less than 300 nm. The twin lines are separated by a predominantly particle-free region with the spacing between the lines ranging from 100 μm to 600 μm, where the spacing is a function of ink, substrate, and printing conditions. The effect of substrate surface and jetting parameters on nanoparticle line morphology is presented. Arrays of such lines have been printed and evaluated as potential transparent conducting films, showing an effective sheet resistance of ∼5 Ω/□. This edge-enhanced twin-deposition technique has the potential for rapid, material-efficient, and lithography-free patterned deposition of functional material for use in roll-to-roll manufacturing.

Bottom-up design of materials via self-assembly with appropriate building blocks offers the possibility of developing innovative three-dimensional all synthetic materials with new functionalities. Helical optically active poly(3-methyl-4-vinylpyridine)/(R) and (S) mandelic acid and helical optically active poly(3-methyl-4-vinylpyridine) (P3M4VP)/ D- and L- amino acid complexes have been prepared. A diblock copolymer of helical poly[(3-methyl-4-vinylprydine)/mandelic acid complex]-block-poly(styrene) has been processed into smectic layer-like helical-bundle structures on silicon wafer. Additionally, optically active helical poly(2-methoxystyrene) (P2PMS) has been synthesized and the surfaces of the chiral helical P2MS have been shown to be effective as supports for mouse and human osteoblast cells. The cell attachment and growth data demonstrate that the chiral P2MS surfaces were better supports compared to achiral P2MS surfaces.

In this work the effect on the adsorption of Cr (VI) by thermally treated Hydrotalcite-like Material (HTM) synthesized by the sol-gel method with a Mg/Al = 2 was studied. The characterization of the HTM before and after Cr (VI) removal, as well as the kinetic studies were carried out. When the HTM are thermally treated at 350ºC the hydrotalcite crystalline structure remains and the textural properties improve. The Cr (VI) adsorption capacity of HTM was 125 mg of Cr (VI) / g of HTM. This capacity augments at 132 mg of Cr (VI) / g of HTM after heating HTM at 300°C. The crystallinity as well the porosity of the HTM diminished after adsorption of Cr (VI), due to the obstruction of both the pores and the interlayer space. The adsorption of Cr (VI) occurred before 4 minutes contact time. It can be concluded that HTM exhibits a high Cr (VI) adsorption capacity in a short time.

Supercapacitors are promising candidates for alternative energy storage applications since they can store and deliver energy at relatively high rates. In this work, we integrated large area chemical vapor deposition (CVD) grown three dimensional graphene heterostructures with high capacitance metal oxides (MnO2) to fabricate highly conductive, large surface-area composite thin films. Uniform, large area 3D graphene heterostructures layers were produced by a one-step CVD on nickel foams. MnO2 nanowires were deposited on the as-obtained 3D graphene heterostructures film by a simple chemical bath depostion process. The oxide loading of the 3D graphene/MWNTs/MnO2 nanowires (GMM) composite films can be simply controlled by deposition time and nanowire solution concentration. The surface morphology was investigated by scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM), and Energy-dispersive X-ray spectroscopy (EDS) was performed to characterize the MnO2on the surface of the film. By introducing the fast surface redox reactions into the graphene heterostructures film via integrating pseudocapacitive material like MnO2, the capacitive ability of the system enhanced dramatically. Supercapacitor was fabricated based on the 3D graphene heterostructures /MnO2 hybrid film electrodes; the measurements of cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) are conducted to determine its performance for the electrodes of supercapacitors.

Mechanical cues in cellular microenvironment are central in directing aclass of cellular behaviors such as the dynamic of cell adhesion, migration,and differentiation. Several advanced optical techniques, such asstructured-illumination nano-profilometry (SINAP), have been developed for abetter resolution of these dynamic processes. These techniques howeverrequire culturing cells on materials of refractive index close to that ofglass, while most studies regarding the effects of mechanical cues oncellular dynamics were conducted on hydrogel-based substrates. Here wereport the development of culturing substrates of tunable rigidity andrefractive index suitable for SINAP studies. Polyvinyl chloride (PVC)-basedsubstrates were mixed with a softener called Di(isononyl)Cyclohexane-1,2-Dicarboxylate (DINCH) and cured by heating. The volumeratios of PVC to DINCH were varied from 1:1 to 3:1. The Young’s modulus ofthe resulting substrates ranged from 18 kPa to 40 kPa. The yieldedrefractive indices of the composite substrates as measured by phase contrasttomography ranged from 1.47 to 1.53. Human lung adenocarcinoma cells CL1-5were cultured on the composite substrates and cell viability was examinedusing the MTT assay. The dynamics of cell adhesion and filopodia activitieswere examined using SINAP. Preliminary results suggest that PVC basedculturing substrates have a great potential in the application of SINAPbased studies.

Adequate mechanical properties are important for both structural and functional applications of materials. There are significant differences in mechanical behaviour of different B2 ordered alloys and these are related to the properties of superlattice dislocations. Several types of dislocations can be activated, in particular <111> and <001> dislocations gliding on {110} planes. Their mobility can vary markedly from material to material and this has a strong impact on the mechanical properties. With the aim to elucidate qualitatively the differences between different alloys crystallising in the same B2 structure we analyse possible dislocation dissociations. The model employed is based on the isotropic elasticity but includes an important characteristic of stacking-fault-like defects involved in the splittings, the deviation of their displacements away from the usually assumed ½<111> APB.

Semiconductor devices have been improved by using delta-doped quantum well (DDQW) of impurities due to the great amount of charge carriers it provides. The first proposals consisted of a DDQW close to the Schottky barrier potential in the gate terminal in a FET [1]. In this work we reported the energy levels spectrum for n-type double-DDQW with a Schottky barrier (SB) at their neighborhood in a Gallium Arsenide (GaAs) matrix. In addition to consider only the linear optical approximation we take into account the third order correction to the absorption coefficient and the refractive index change. We report those properties as a function of the Schottky Barrier Height (SBH), several separation distances between the DDQWs, and hydrostatic pressure effects. The results shown that the magnitude of intensity resonance peaks are controlled by the asymmetry of the DDQW+SB.

Phosphorylcholine glyceraldehyde (PCGA) was used as a phosphorylcholine (PC) group containing compound to graft onto the surface of polycarbonateurethane (PCU) film using 1,6-hexanediamine (HDA) or α,ω-diamino-poly(ethylene glycol) (APEG, Mn = 200) as a spacer, in order to introduce biomimetic structure onto the polymer surface. X-ray photoelectron spectroscopy (XPS) analysis shows that PCGA has been covalently linked to the PCU surface. Water contact angle test suggests that the surface hydrophilicity has been improved after PCGA is grafted onto the surface of PCU film. Scanning electron microscope (SEM) observation of the modified PCU films after contacting with plasma-rich plasma demonstrates that platelets rarely adhere but a large number of platelets adhere to the original PCU surface. The hemocompatibility of the PC modified PCU film has been improved obviously after grafting with PCGA with PEG spacer.

The effect of Sb on the formation of Ge nano islands in Si by means of molecular beam epitaxy is reported. We observe in the Ge/Si(100) system a non-monotonic dependence of the Stranski-Krastanov critical thickness of Ge islands formation on the adsorbed Sb amount. Dome- and hut-shaped Ge islands are replaced with the pyramids, when Ge is deposited on the Sb-covered Si(100) surface. The Sb-mediated conservation of the shape of Ge islands during embedding them in Si is shown. We assume that the decrease of the surface diffusion of Si and Ge ad-atoms causes these effects.

Nitrogen-doped ZnO (ZnO:N) films have been prepared by remote plasma atomic layer deposition (RP-ALD) and treated by rapid thermal annealing (RTA) in oxygen atmosphere. The local electronic structures of the (ZnO:N) films were investigated by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge spectroscopy (XANES) at the O K-edge. The XPS reveals the presence of the Zn-N bond in the ZnO:N films, indicating that partial amounts of oxygen sites are occupied by nitrogen species. This is correspondent with the decrease of electron concentration in ZnO:N films with the nitrogen doping concentration, as indicated by the Hall effect measurement. The RP-ALD technique was applied to fabricate the n-type ZnO:N/p-type GaN heterojunction LEDs. Dominant ultraviolet electroluminescence at 371 nm from the ZnO:N layer was observed at room temperature.

We have deposited porous ZnO films on aluminum-doped ZnO (ZnO/AZO) and fluorine-doped tin oxide (ZnO/FTO) transparent substrates, and annealed both in air at 500°C. X-ray diffraction measurements of the nanoporous ZnO films after heat treatment showed that, ZnO/AZO film exhibited a dominant (002) diffraction while the ZnO/FTO showed mixed diffraction peaks with the (100) and (101) being dominant. Dye-sensitized solar cells (DSC) based on the sensitization of the porous ZnO films on AZO and FTO substrates with an indoline dye were constructed. The photoaction spectrum, which is a measure of the degree of sunlight harvesting, was broad and higher in the ZnO/AZO DSC than that of the ZnO/FTO DSC. Conversion efficiency of 7.3 % was obtained for the ZnO/AZO DSC while 4.5 % was recorded for the ZnO/FTO. The superior photovoltaic performance of the ZnO/AZO DSC is attributed to better ZnO film orientation after thermal treatment and the higher sunlight harvesting.

Sulfate attack on concrete has been studied worldwide for more than 60 years. However, the mechanisms of attack are still not entirely understood, and deterioration of concrete from sulfates still occurs. The source of the sulfates may be either external or internal. External sources are the naturally occurring sulfates in the environment or those sulfates that are the product of industrial processes or various human activities (e.g. fertilizers often release sulfates into the soil and groundwater). Internal sources of sulfates may include the sulfates introduced in the cements from which concrete is made. The purpose of this study is to find out the amount of sulfates that concrete can withstand in the water. Standards tests have been developed to evaluate the resistance of concretes to sulfate attack. Some, but not all of these tests, take into account the mechanisms of sulfate attack so far discovered in research work. The tests range from those that monitor changes in the strength of concrete specimens after set periods of immersion in known compositions sulfate solutions, to those that use x- ray diffraction to examine concrete specimens for expansive products (e.g. ettringite and thaumasite) that have resulted from sulfate attack.

An electrochemical study was carried out in order to obtain the effects of the turbulent flow condition on the stainless steel corrosion immersed in natural seawater using an electrochemical corrosion technique like electrochemical impedance spectroscopy (EIS). A three-electrode electrochemical glass cell was used to obtain the electrochemical measures, where a cylinder of the AISI 410 stainless steel was used as working electrode, a saturated calomel electrode as reference electrode and a synthesised graphite rod as auxiliary electrode. 24 hours was the total exposure time. In order to control the hydrodynamic conditions a rotating cylinder electrode (RCE) was used and, a scanning electron microscope (SEM) was used in order to obtain the superficial analyses of the metallic surface after tests. The results of the electrochemical techniques shown that at 1000 rpm of the rotation speed, the corrosion rate (CR) increased as the exposure time also increased. In additions, in the other rotations speed (2000, 3000 and 5000 rpm), the CR was affected by the corrosion products formed on metallic surface. t is important to point out that the corrosion morphology found in the steel sample was localized corrosion.

Exact locations of conductive filaments formed in NiO-based resistive switching (RS) cells were detected by C-AFM, and their electrical as well as chemical properties were investigated. After a forming process, a part of top electrodes of Pt/NiO/Pt RS cells is deformed. NiO layers are also deformed, and conductive spots, i.e. filaments have been found preferentially along the edges of deformations. Detailed C-AFM investigation has revealed that variation of cell resistances originates from differences in size and shape of filaments, not their resistivity. Furthermore, cross-sectional TEM analysis has demonstrated that filaments determining cell resistance consist of reduced NiO with an inclusion of Pt.

Si nanowires (NWs) have been fabricated by Ag-assisted electroless etching technique using an HF/AgNO3 aqueous solution. Scanning electron microscopy (SEM) measurements have revealed that a highly dense array of Si NWs with length of ∼1.4 μm is formed over the surface of both n-type and p-type Si (100) substrates. Following the fabrication of Si NWs, electron-beam evaporated p-type AgGa0.5In0.5Se2 thin film was deposited on the n-type Si NWs to form p-n heterojunction solar cells. The fabricated solar cells yield a 5.50% power conversion efficiency under AM (1.5) illumination.

As technology advances, ever smaller wires are needed for devices, for applications in electronics, medicine, and clean energy. Many of these applications will require the precise control of not only wire shapes and diameters, but alloy compositions as well. The recently developed technique of Electroplate-and-Lift (E&L) Lithography developed by our group has demonstrated the capability of quickly and easily producing patterned micro- and nanowires of a large variety of electrodeposited materials. Here we report the first E&L- based synthesis of microwires with controlled alloy compositions, in the model system of bronze.

Wires of several different compositions, ranging from 100% copper to 100% tin, were deposited on patterned ultrananocrystalline diamond (UNCD)TM templates, by varying the relative concentrations of copper and tin salts in the plating solution. All wires were deposited at 55oC, -1.0 V vs. the saturated calomel electrode (SCE). Wire morphology and elemental composition was observed with scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS). For some alloy compositions, wires were interrupted at irregular intervals by nodules. All alloy wires were highly enriched in copper relative to the solution composition.

The pin-on-disc wear behavior of nanostructured two-phase Fe30Ni20Mn20Al30 and eutectic lamellar-structured Fe30Ni20Mn35Al15 is compared emphasizing the influence of the microstructure and mechanical properties of alloys as well as the effect of test environment. Although the wear of both alloys was greater in oxygen-containing environments, eutectic Fe30Ni20Mn35Al15 is less sensitive to oxygen than nanostructured Fe30Ni20Mn20Al30. Abrasive wear dominated during the wear in all cases, while plastic deformation also occurred during the wear of eutectic Fe30Ni20Mn35Al15. A tribolayer of zirconia, which was embedded in the surface of the wear pin, was characterized using a scanning transmission electron microscope equipped with an energy dispersive spectrometer.

Studies have revealed that different dislocation types have different influences on GaN device performance. Identification and discrimination of dislocation types in GaN films will be very helpful to understand the formation mechanism of each type of dislocation, and subsequently to work out corresponding methodologies to reduce each. In this work, two types of etched pits, inverted triangle and trapezoidal, were discovered in GaN films by AFM. Triangle ones were more quickly generated, and would transfer to the other with the increase in etching duration. Theoretical analysis from the viewpoint of strain energy of defects lets us to conclude that the former is from screw dislocation and the latter is formed by mixed dislocation. We consequently obtained the dislocation densities of each type, which agreed well with the XRD results. In summary, this work presents an easy but reliable approach to determine the type and corresponding density of dislocations in GaN.

Gold nanoparticles (AuNp) formed using alkoxysilane precursors are utilizedin the development of thin organically modified silicates (ormosil) films.The resulting films are optically transparent thereby retaining the opticalproperties of AuNp. Surface morphology shows that the in situ generated AuNp retained their nanogeometry in the ormosilfilms. An application of the AuNp encapsulated ormosils is shown inelectrocatalytic determination of hydrogen peroxide. For this purpose,potassium ferricyanide is chosen as electron transfer mediator and isencapsulated in the films. Results show that the presence of AuNp in theormosil matrix dramatically improves the electrochemical behavior ofpotassium ferricyanide. The ormosil films are utilized for electrocatalyticdetermination of hydrogen peroxide. In order to investigate thebiocompatibility of the ormosil film, horseradish peroxidase (HRP) isincorporated resulting in improvement in oxidation and reduction ofperoxide.