The effect of oxygen vacancy (VO) on the electronic and magnetic properties of ZnCoO was studied with first principle methods based on density functional theory (DFT). Calculations were performed, on a periodic 3×3×3 wurtzite supercell of ZnO which consists of 108 atoms with two Co ions substituted for two Zn atoms, using the generalized gradient approximation with Hubbard U correction method (GGA+U). We have studied the interatomic exchange interaction with and without VO for different configurations with different magnetic atom lattice arrangements. The total energies, electronic structures and magnetic moments were calculated for each configuration.

The objective of this study was to assess usability of silver nanoparticles loaded on amorphous carbon (Ag-C) hollow nanospheres for the removal of Methylene Blue (MB) molecules from aqueous solutions. Using microwave technique, silver nanoparticles of different weight ratio was deposited onto amorphous carbon templates. The carbon hollow spheres were derived from glucose using hydrothermal technique. Interestingly crystallite size of Ag decreased with the silver loading on carbon nanospheres. Using UV-vis spectroscopy, the kinetics of MB removal from the solution was assessed. The degradation of MB followed pseudo-first-order kinetics. The obtained results showed that Ag-C particles are efficient MB degradation agent with the rate constant as high as 0.19 m-1 under visible light and 0.041 m -1 under UV light. Thus Ag-C particles are good alternative as low-cost scavenger of dye molecules in wastewater treatments.

In this study, we demonstrate the fabrication of hybrid membranes that exhibit discrete and reversible changes in permeability in response to changes in calcium ion (Ca2+) concentration and temperature. Fusion proteins comprising calmodulin (CAM) and elastin-like polypeptides (ELPs) were used as stimuli-responsive elements due to their ability to undergo a reversible lower critical solution temperature (LCST) phase transition, which is sensitive to Ca2+ binding. The calmodulin elastin-like polypeptides fusions (CAM-ELPs) were incorporated into polymerizing silica networks using a simple sol-gel process and spin coating. Permeation experiments with solutions of crystal violet showed that the membranes are both Ca2+-responsive and thermally responsive. Under suitable pressure drop across the membranes, in the absence of Ca2+ or below the LCST of the ELPs, the hybrid membranes are impermeable to water. After addition of Ca2+ or above the LCSTs, they become permeable to water. The permeability can be toggled back and forth by sequential addition of calcium and ethylenediamine tetraacetic acid (EDTA). These results demonstrate that CAMELP/silica hybrid membranes can serve as tunable molecular filters whose permeability can be switched on and off in response to Ca2+ and temperature.

Cystic fibrosis (CF) is an inherited childhood-onset life-shortening disease. It is characterized by increased respiratory production, leading to airway obstruction, chronic lung infection and inflammatory reactions. The most common bacteria causing persisting infections in people with CF is Pseudomonas aeruginosa. Superparamagnetic Fe3O4 iron oxide nanoparticles (NPs) conjugated to the antibiotic (tobramycin), guided by a gradient of the magnetic field or subjected to an oscillating magnetic field, show promise in improving the drug delivery across the mucus and P. aeruginosa biofilm to the bacteria. The question remains whether tobramycin needs to be released from the NPs after the penetration of the mucus barrier in order to act upon the pathogenic bacteria. We used a zero-length 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) crosslinking agent to couple tobramycin, via its amine groups, to the carboxyl groups on Fe3O4 NPs capped with citric acid. The therapeutic efficiency of Fe3O4 NPs attached to the drug versus that of the free drug was investigated in P. aeruginosa culture.

Nanobiosensors have drawn significant research interest in recent years owing to the advantages of label-free, electrical detection. However, nanobiosensors fabricated by bottom-up process are limited in terms of yield and device uniformity due to the challenges in assembly. Nanobiosensors fabricated by top-down process, on the other hand, exhibit better uniformity but require time and costly processes and materials to achieve the critical dimensions required for high sensitivity. In this report, we introduce a top-down nanobiosensor based on polysilicon nanoribbon. The polysilicon nanoribbon devices can be fabricated by conventional photolithography with only materials and equipments used in the standard CMOS process, thus resulting in great time and cost efficiency, as well as scalability. The devices show great response to pH changes with a wide dynamic range and high sensitivity. Biomarker detection is also demonstrated with clinically relevant sensitivity. Such results suggest that polysilicon nanoribbon devices exhibit great potential toward a highly efficient, reliable and sensitive biosensing platform.

The long-term behavior of nuclear glass subjected to alpha radiation by minor actinides must be investigated with a view to geological disposal. This study focuses on the effect of alpha radiation on the chemical reactivity of R7T7 glass with pure water, mainly on the residual alteration rate regime. A glass specimen doped with 0.85 wt% 239PuO2 (α emitter) is leached under static conditions in argon atmosphere at 90°C and at a high surface-area-to-volume ratio (S/V = 20 cm−1). The alteration rate is monitored by the release of glass alteration tracer elements (B, Na and Li). Radiation effects on the leached glass and its gel network are characterized by SEM and TEM analyses. Plutonium release is also measured by radiometry and its chemical oxidation state is assessed by measuring the pH and redox potential of the leachates. The results do not highlight any significant effect of alpha radiation on the residual alteration of this doped glass. This observation is consistent with SEM and TEM characterizations, which show that a protective layer can be formed under alpha radiation. Very low concentrations of soluble plutonium are measured in the leachate. These Pu releases are three orders of magnitude lower than the boron release, indicating strong plutonium retention.

The purpose of this work is the development and control of a high temperature reactor for the production of engineered nanoparticles, taking advantage from our previous studies on combustion-generated fine carbonaceous particles. The reactor consists of a laminar premixed flame, homogenously doped with monodisperse droplets of metal precursors dissolved or dispersed in volatile solvents. The droplets are generated by a vibrating orifice aerosol generator, and injected directly into the burner. Fuel-lean and stoichiometric flames allow producing pure metal oxide particles of nanometric sizes.

Particles are collected by thermophoresis inserting a cold substrate in the flame by means of a pneumatic actuator. Morphological and dimensional analysis are performed on the collected particles by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). SEM and AFM allow inferring both qualitative and quantitative information on many physical properties including size, morphology, surface texture and roughness.

Experimental results have been obtained from a premixed stoichiometric flame of ethylene and air, doped with 75 microns droplets of magnesium nitrate hexahydrate dissolved in ethanol. Roughly monodisperse magnesium oxide particles, having a desired size ranging from 50 nm down to 7 nm, have been produced by altering the precursor concentration in the solution and the residence time of the synthesis process.

While the self-learning kinetic Monte Carlo (SLKMC) method enables the calculation of transition rates from a realistic potential, implementations of it were usually limited to one specific surface orientation. An example is the fcc (111) surface in Latz et al. 2012, J. Phys.: Condens. Matter 24, 485005. This work provides an extension by means of detecting the local orientation, and thus allows for the accurate simulation of arbitrarily shaped surfaces. We applied the model to the diffusion of Ag monolayer islands and voids on a Ag(111) and Ag(001) surface, as well as the relaxation of a three-dimensional spherical particle.

This paper addresses the application of engineered nanocrystalline ultrahydrophilic titanium oxide films to artificial orthopaedic implants. Titanium (Ti) is the material of choice for orthopaedic applications and has been used for over fifty years because of its known bio-compatibility. Recently it was shown that biocompatibility of Ti metal is due to the presence of a thin native sub-stoichiometric titanium oxide layer [1] which enhances the adsorption of mediating proteins on the surface thus enhancing cell adhesion and growth [2,3,4]. Improving the quality of surface oxide, i.e. fabricating stoichiometric oxides as well as nanoengineering the surface topology that matches the dimensions of adhesive proteins, is crucial for the increase of protein adsorption [2] and, as a result, the biocompatibility of Ti implant materials. We have fabricated ultrahydrophilic nano-crystalline transparent films of anatase phase of titania (TiO2) by ion beam assisted deposition (IBAD) processes in an ultrahigh vacuum system. Source material was 99.9% pure rutile TiO2. Various ion beam conditions were used to produce these coatings with different grain sizes (4 to 70 nm) that affect the wettability, roughness, and the mechanical and optical properties of the coating [5]. Our biological experiments have shown that biocompatibility of these ultrahydrophilic nanoengineered TiO2 coatings are superior to commonly used orthopaedic titanium and even hydroxyapatite.

The electrocaloric effect holds promise for possible application in refrigeration technologies. There is much interest in this subject and experimental studies have shown the possibility for creating materials with a modest sized electrocaloric response. However, theoretical studies lag behind the experimental effort due to the lack of computational methods to accurately study the finite temperature response. Here the freely distributed feram, an effective Hamiltonian molecular dynamics method, is demonstrated for predicting the electrocaloric response of BaTiO3.

Bacterial infections are commonly found on paper towels and other paper products leading to the potential spread of bacteria and consequent health concerns. The objective of this in vitro study was to introduce antibacterial properties to paper towel surfaces by coating them with selenium nanoparticles. Scanning electron microscopy was used to measure the size and distribution of the selenium coatings on the paper towels. Atomic force microscopy was used to measure the surface roughness of paper towels before and after coated with selenium nanoparticles. The amount of selenium precipitated on the paper towels was measured by atomic absorption spectroscopy. In vitro bacterial studies with Staphylococcus aureus were conducted to assess the effectiveness of the selenium coating at inhibiting bacterial growth. Results showed that the selenium nanoparticles coated on the paper towel surface were well distributed and semispherical about 50nm in diameter. Most importantly, the selenium nanoparticle coated paper towels inhibited S. aureus growth by 90% after 24 hours and 72 hours compared with the uncoated paper towels. Thus, the study showed that nano-selenium coated paper towels may lead to an increased eradication of bacteria to more effectively clean a wide-range of clinical environments, thus, improving health.

An alternating copolymer containing dithienylcyclopentadienone, thiophene and benzothiadiazole was synthesized by palladium (0) catalyzed Stille coupling reaction. Structural characterization of the synthesized alternating copolymer was carried out by NMR and FTIR spectroscopy. This solution processable copolymer shows an excellent thermal stability and has a broad absorption range from 300-800 nm. High LUMO energy level and low band gap of the synthesized copolymers suggest that, this copolymer will be a better donor material for application in organic photovoltaics. Particle size analysis and molecular weight determination of the synthesized copolymer through dynamic light scattering experiment indicates that, high molecular weight copolymer was obtained by this polymerization route. Photovoltaic devices were fabricated from the blend of copolymer and phenyl-C61- butyric acid methyl ester as the active material. Fabricated photovoltaic device results show that this alternating copolymer is a promising candidate for use in organic photovoltaics.

The SrZnO2 thin films were fabricated by using laser ablation method. The films were annealed after deposition in order to improve the crystallinity. Water splitting experiments were carried out and hydrogen production over the SrZnO2 thin films were confirmed with no applied bias. The band gap of SrZnO2 was 3.41 eV which is 0.15 eV larger than that of ZnO. It suggests that the band gap was increased by doping Sr to ZnO, and the reducibility was improved. As a result, the rate of photocatalytic hydrogen production over the SrZnO2 was increased compared to ZnO.

The purpose of this paper is the design of simple combinational optoelectronic circuit based on SiC technology, able to act simultaneously as a 4-bit binary encoder or a binary decoder in a 4-to-16 line configurations. The 4-bit binary encoder takes all the data inputs, one by one, and converts them to a single encoded output. The binary decoder decodes a binary input pattern to a decimal output code.

The optoelectronic circuit is realized using a a-SiC:H double pin/pin photodetector with two front and back optical gates activated trough steady state violet background. Four red, green, blue and violet input channels impinge on the device at different bit sequences allowing 16 possible inputs. The device selects, through the violet background, one of the sixteen possible input logic signals and sends it to the output.

Results show that the device acts as a reconfigurable active filter and allows optical switching and optoelectronic logic functions development. A relationship between the optical inputs and the corresponding digital output levels is established. A binary color weighted code that takes into account the specific weights assigned to each bit position establish the optoelectronic functions. A truth table of an encoder that performs 16-to-1 multiplexer (MUX) function is presented.

Shape memory nanocomposites were produced following a simple one-step synthesis route initiated by a series of molar mixtures of POSS thiol nanocages and pentaerythritol tetrakis (3mercaptopropionate), and a diacrylate polycaprolactone (PCL) with Mn=3,000 g/mol. Simultaneous wide- and small- angle X ray scattering (WAXS/SAXS), differential scanning calorimetry (DSC) and atomic force microscopy (AFM) experiments were carried out and results were correlated on microstructure. Molecular identification was performed by Fourier transformed infrared (FTIR-ATR). Thermomechanical shape memory cycles revealed that the nanocomposites achieved excellent shape recovery (99%) and shape fixity (100%) parameters. Dynamic mechanical analysis showed that elastomeric modulus decrease in function of the POSS thiol molar concentration and this result is correlated with the decrease in average crosslink density (ν). WAXS studies revealed orthorhombic crystallites for PCL combined with an amorphous POSS phase when the molar concentration of POSS was low (2.5%, 5%, 10%). However, increasing the molar concentration of POSS thiol until 20%, a broad and weak reflection centered around 2θ =7.9° which corresponded to imperfect POSS crystals. At the nanoscale, SAXS analysis showed lamellar nanostructure formation for all POSS/polycaprolactone crosslinked networks. Strikingly, induced anisotropic orientation of polycaprolactone lamellar nanostructure was observed when the concentration of POSS increased to 10 and 20 mol%.

It is well known that the cadmium chloride annealing treatment is an essential step in the manufacture of efficient thin film cadmium telluride solar cells. It has been recognized that the combination of annealing at ∼4000C together with the addition of cadmium chloride at the surface induces re-crystallisation of the cadmium telluride layer and also affects the n-type cadmium sulfide. We have applied advanced micro-structural characterization techniques to distinguish the effect of the annealing and the cadmium chloride treatments on the properties of the cadmium telluride deposited via close space sublimation (CSS) and relate these observations to device performance. Transmission electron microscopy (TEM) has shown a variation in stacking fault density with annealing temperature and annealing time. Stacking faults observed within the cadmium telluride grains in TEM were partially removed post annealing; these findings show that temperature alone has a role in the reduction of stacking faults. However, since we have previously observed almost complete removal of stacking faults with annealing in combination with cadmium chloride, the cadmium chloride is essential to defect removal and high efficiency cells.

The present investigation work shows the results of Cd1-XZnXS thin films (where X= 0.04, 0.08, 0.12, 0.16 and 0.2), obtained by total ammonia-free chemical bath processes. The reaction solutions were prepared with precursors of metallic salts as CdCl2 and ZnCl2 and replacing the ammonia with trisodic citrate (C6H5O7Na3) as complexing agent. The reaction solutions were stabilized with KOH to get alkaline solutions. As result of adding Zn, the as deposited films showed changes in their morphological, structural and optical properties. Moreover, additional changes were obtained when thermal treatments to 400°C under N2 environment were applied to the as deposited films. The agglomerates at the surface of the annealed films showed larger grain sizes compared to that of the as deposited films. Due to preferential orientation of the hexagonal wurtzite-type structure in the films, changes in the intensity in the (002), (100) and (101) peaks from x-ray diffraction analysis were observed. Finally, a reduction on the maximum energy band gap from 2.65 to 2.59 eV was obtained as effect of the annealing treatment to the films.

Methods of “green” synthesis of nanoparticles of elemental iron (zero-valent iron, NZVI), its oxides and hydroxides using natural products are reviewed. In particular, the use of biological agents such as extracts of various plants, tea, soya, table sugar and glucose, as reductants and as capping agents is shown. The techniques involved are simple, environmentally friendly and generally one-pot processes. Water disinfection using iron nanomaterials against viruses and bacteria is also examined.

Amongst the list of the measurands specific to nanoparticles, size and shape definitely matter but surface chemistry is also often cited. While it is now largely recognized that surface composition, structure and reactivity are perhaps the dominant parameters controlling properties of nanoparticles, surface chemistry is one of the key characteristics of nanoparticles which is seldom or inappropriately evaluated, as it has been identified by international organizations (such as ISO, BIPM or CEN). The usual techniques for surface analysis of materials often require ultra-high vacuum (UHV) conditions and are hardly applicable to nanoparticles. Moreover, because the surface chemical composition and reactivity are dependent on the environmental conditions, the results obtained under UHV cannot be extrapolated to nanoparticles in ambient atmosphere or dispersed in liquids.

After an analysis of the stakes and challenges in the surface characterization of nanoparticles and a very brief overview of the usual techniques for surface studies, this paper presents the performance of Fourier transform infrared (FTIR) spectroscopy to investigate surface chemical composition, surface reactivity and surface functionalization of nanoparticles. As illustrating examples, the results of the FTIR surface analysis of different kinds of ceramic nanoparticles are discussed with regard to several fields of applications.