Hydrogen Gas Response of Zn1 – xAgxOy and Cu1 – xZnxOy Nanostructured Films

Detection of hydrogen gas in industry, biomedical systems and combustion systems is important for safety reasons. Silver doping in zinc oxide and zinc doping in copper oxide were investigated to obtain improved hydrogen sensing performances for sensors. Samples were grown by chemical method and studied by X-ray diffraction, SEM and sensorial techniques. For selectivity study samples were exposed to hydrogen, methane and ethanol gases. Were found growth and annealing regimes which allow us fabrication of faster and more selective gas sensors based on Zn1-xAgxOy nanostructured films and nanocrystallite Cu1-xZnxOy films with respect to 100 ppm H2

PRODUCTION OF MURINE POLYCLONAL ANTI FtsZ P.aeruginosa ANTIBODIES

Summary In order to overcome the crisis of antibiotic resistance, there is an urgent need for alternative antibacterial agents that have novel mechanisms of action. FtsZ is an attractive target for antibacterial drug discovery because of its widespread conservation in the bacterial kingdom, its absence in the mitochondria of higher eukaryotes and its known biochemical activity and molecular structure. FtsZ plays an essential role in prokaryotic cell division machinery in which undergoes GTP-dependent polymerization midcell and assembles into the dynamic Z-ring at the site of division. The Z-ring acts to initiate Z-ring contraction to form bacterial daughter cells. Although FtsZ shares structural and functional similarity with eukaryotic tubulin, most of the tubulin/microtubule targeting agents do not affect the dynamic assembly of FtsZ, indicating that FtsZ can be a selective antibacterial target. In this study, we evaluated the immunogenicity in mice of FtsZ protein from Pseudomonas aeruginosa bacterium, which is a well-known opporthunistic human pathogen. We were interested in the degree of affinity and titer dynamics of polyclonal antibodies synthesized against Pseudomonas aeruginosa FtsZ by mice reimmunization and also, in antiFtsZ antibodies reactivity with their specific protein, FtsZ Pseudomonas aeruginosa

Ethanol Sensing Performances of Zinc-doped Copper Oxide Nano-crystallite Layers

The synthesis via chemical solutions (aqueous) (SCS) wet route is a low-temperature and cost-effective growth technique of high crystalline quality oxide semiconductors films. Here we report on morphology, chemical composition, structure and ethanol sensing performances of a device prototype based on zincdoped copper oxide nanocrystallite layer. By thermal annealing in electrical furnace for 30 min at temperatures higher than 550 ˚C, as-deposited zinc doped Cu2O samples are converted to tenorite, ZnxCu1-xOy, (x=1.3wt%) that demonstrate higher ethanol response than sensor structures based on samples treated at 450 ˚C. In case of the specimens after post-growth treatment at 650 ˚C was found an ethanol gas response of about 79 % and 91 % to concentrations of 100 ppm and 500 ppm, respectively, at operating temperature of 400 ˚C in air

Hydrogen Gas Response of Zn1 – xAgxOy and Cu1 – xZnxOy Nanostructured Films

Detection of hydrogen gas in industry, biomedical systems and combustion systems is important for safety reasons. Silver doping in zinc oxide and zinc doping in copper oxide were investigated to obtain improved hydrogen sensing performances for sensors. Samples were grown by chemical method and studied by X-ray diffraction, SEM and sensorial techniques. For selectivity study samples were exposed to hydrogen, methane and ethanol gases. Were found growth and annealing regimes which allow us fabrication of faster and more selective gas sensors based on Zn1-xAgxOy nanostructured films and nanocrystallite Cu1-xZnxOy films with respect to 100 ppm H2

Optical properties of ZnO nanowire arrays electrodeposited on n-and p-type Si(1 1 1): Effects of thermal annealing

a b s t r a c t Electrodeposition is a low temperature and low cost growth method of high quality nanostructured active materials for optoelectronic devices. We report the electrochemical preparation of ZnO nanorod/nanowire arrays on n-Si(1 1 1) and p-Si(1 1 1). The effects of thermal annealing and type of substrates on the optical properties of ZnO nanowires electroplated on silicon (1 1 1) substrate are reported. We fabricated ZnO nanowires/p-Si structure that exhibits a strong UV photoluminescence emission and a negligible visible emission. This UV photoluminescence emission proves to be strongly influenced by the thermal annealing at 150-800 • C. Photo-detectors have been fabricated based on the ZnO nanowires/p-Si heterojunction

Tuning ZnO Sensors Reactivity toward Volatile Organic Compounds via Ag Doping and Nanoparticle Functionalization

Nanomaterials for highly selective and sensitive sensors toward specific gas molecules of volatile organic compounds (VOCs) are most important in developing new-generation of detector devices, for example, for biomarkers of diseases as well as for continuous air quality monitoring. Here, we present an innovative preparation approach for engineering sensors, which allow for full control of the dopant concentrations and the nanoparticles functionalization of columnar material surfaces. The main outcome of this powerful design concept lies in fine-tuning the reactivity of the sensor surfaces toward the VOCs of interest. First, nanocolumnar and well-distributed Ag-doped zinc oxide (ZnO:Ag) thin films are synthesized from chemical solution, and, at a second stage, noble nanoparticles of the required size are deposited using a gas aggregation source, ensuring that no percolating paths are formed between them. Typical samples that were investigated are Ag-doped and Ag nanoparticle-functionalized ZnO:Ag nanocolumnar films. The highest responses to VOCs, in particular to (CH3)2CHOH, were obtained at a low operating temperature (250 °C) for the samples synergistically enhanced with dopants and nanoparticles simultaneously. In addition, the response times, particularly the recovery times, are greatly reduced for the fully modified nanocolumnar thin films for a wide range of operating temperatures. The adsorption of propanol, acetone, methane, and hydrogen at various surface sites of the Ag-doped Ag8/ZnO(0001) surface has been examined with the density functional theory (DFT) calculations to understand the preference for organic compounds and to confirm experimental results. The response of the synergistically enhanced sensors to gas molecules containing certain functional groups is in excellent agreement with density functional theory calculations performed in this work too. This new fabrication strategy can underpin the next generation of advanced materials for gas sensing applications and prevent VOC levels that are hazardous to human health and can cause environmental damages

Study of deposition parameters for the fabrication of ZnO thin films using femtosecond laser

Femtosecond (fs) pulsed laser deposition (fs-PLD) of ZnO thin film on borosilicate glass substrates is reported in this work. The effect of important fs-PLD parameters such as target–substrate distance, laser pulse energy and substrate temperature on structure, morphology, optical transparency and luminescence of as-deposited films is discussed. XRD analysis reveals that all the films grown using the laser energy range 120–230 μJ are polycrystalline when they are deposited at room temperature in a ~10−5 Torr vacuum. Introducing 0.7 mTorr oxygen pressure, the films show preferred c-axis growth and transform into a single-crystal-like film when the substrate temperature is increased to 100 °C. The scanning electron micrographs show the presence of small nano-size grains at 25 °C, which grow in size to the regular hexagonal shape particles at 100 °C. Optical transmission of the ZnO film is found to increase with an increase in crystal quality. Maximum transmittance of 95 % in the wavelength range 400–1400 nm is achieved for films deposited at 100 °C employing a laser pulse energy of 180 μJ. The luminescence spectra show a strong UV emission band peaked at 377 nm close to the ZnO band gap. The shallow donor defects increase at higher pulse energies and higher substrate temperatures, which give rise to violet-blue luminescence. The results indicate that nano-crystalline ZnO thin films with high crystalline quality and optical transparency can be fabricated by using pulses from fs lasers

Effect of [OH-] linkages on luminescent properties of ZnO nanoparticles

Optical properties of ZnO nanoparticles prepared from a simple chemical method using sodium zincate bath show strong white light emission. X-ray absorption fine structure studies reveal a completely different local environment around Zn in these ZnO nanoparticles. The observed luminescence properties and local structural changes have been explained on the basis of a linkage between Zn and OH- ions in the surface layers of ZnO nanoparticles.Comment: J. Phys. Chem. C. (2011) (in print