Synthesis and properties of nickel-cobalt-boron nanoparticles

morphous cobalt nickel boride nanoparticles were synthesised by chemical reduction synthesis in aqueous solution. Careful control of synthesis conditions and post reaction oxidation enabled the nanoparticles to be converted into a core-shell structure comprising of an amorphous Co–Ni–B core and an outer metal oxide sheet. These particles had interesting magnetic properties including saturation magnetisations and coercivities of the order of 80 emu/g and 170 Oe respectively, making them suitable for a potential use as an exchange-pinned magnetic material

Halide doping effects on transparent conducting oxides formed by aerosol assisted chemical vapour deposition

We report on the effect of halide doping on the Aerosol-assisted Chemical Vapour Deposition of tin oxide. Specifically, the importance of precursor interactions is highlighted. A halide exchange reaction involving part substitution of the tin precursor is believed to occur in the solvent; the complex acting as a marker for improved films with improved transparent-conducting properties. Precursor mixtures of butyltin trichloride and potassium halide (X = F, Cl, Br, I) in propan-2-ol were deposited at a substrate temperature of 450 °C using air carrier gas. Hall Effect results indicate that fluorine gave the best performing n-type transparent conducting thin films that exhibited high optical transparency (> 80% at 550 nm) and resistivity values of 4.9 × 10− 4 Ω.cm, with charge carrier density and carrier mobility values of 8.85 × 1020 cm− 3 and 15 cm3/V.s respectively. Such parameters yield high figures of merit

White Light-Activated Antimicrobial Paint using Crystal Violet

Crystal violet (CV) was incorporated into acrylic latex to produce white-light-activated antimicrobial paint (WLAAP). Measurement of the water contact angle of the WLAAP showed that the water contact angle increased with increasing CV concentration. In a leaching test over 120 h, the amount of CV that leached from the WLAAPs was close to the detection limit (1.8 log) at the highest CV concentration (1000 ppm). These WLAAPs are promising candidates for use in healthcare facilities to reduce HAIs

Hydrocarbon detection with metal oxide semiconducting gas sensors modified by overlayer or admixture of zeolites Na-A, H-Y and H-ZSM-5

A control thick-film SnO2 gas sensor was modified with zeolites holding LTA, FAU and MFI frameworks using two different approaches to integrate them into the gas-sensing interface. The objective was to prompt selectivity and sensitivity enhancements that were otherwise unattained with the unmodified material when detecting a range of hydrocarbon vapours with similar molecular structures and kinetic diameters. Molecules with different functional groups were also explored. Overlayers were designed by screen-printing 1 or 3 zeolite depositions on top of the control sensor. Admixtures were prepared by screen-printing composites of the control material with 10% (w/w) and 30% (w/w) of zeolite. Tests were performed against ethane, propane, butane, ethanol, isopropanol, acetone, toluene and carbon monoxide at concentrations in the 2.5–125 ppm range and sensors were heated to temperatures in the 250–500 °C range. Sensors were also exposed to humid air and to a mixture of ethane and humid air to assess the selective capabilities of the sensing materials in mixed-gas environments. Both fabrication methods provided sensor responses that, combined, favoured vapour discrimination in a way unachievable with the control sensor and the presence of zeolite was seen to assist in sensitivity and selectivity enhancements towards vapours, whilst providing stable and repeatable responses over time

White-Light-Activated Antibacterial Surfaces Generated by Synergy between Zinc Oxide Nanoparticles and Crystal Violet

The prevalence of hospital-acquired infections (HAIs) caused by multidrug-resistant bacteria is a growing public health concern worldwide. Herein, a facile, easily scalable technique is reported to fabricate white-light-activated bactericidal surfaces by incorporating zinc oxide (ZnO) nanoparticles and crystal violet (CV) dye into poly(dimethylsiloxane). The effect of ZnO concentration on photobactericidal activity of CV is investigated, and we show that there is synergy between ZnO and CV. These materials showed highly significant antibacterial activity when tested against Staphylococcus aureus and Escherichia coli under white light conditions. These surfaces have potential to be used in healthcare environments to decrease the impact of HAIs

Synthesis and material characterization of amorphous and crystalline (alpha-) Al2O3 via aerosol assisted chemical vapour deposition

The facile synthesis of Al2O3 in the amorphous and corundum phase on both glass and quartz substrates is reported. The synthesis was carried out via aerosol assisted chemical vapour deposition using Al(acac)3 and methanol. The films were analyzed using XRD, SEM, UV-vis spectroscopy and XPS. The coatings were highly crystalline (when annealed) with low carbon contamination levels and a relatively featureless morphology that gave rise to ultra high transparency in the UV, visible and near IR portions of the electromagnetic spectrum

Gaseous Photocatalytic Oxidation of Formic Acid over TiO2: A Comparison between the Charge Carrier Transfer and Light-Assisted Mars-van Krevelen Pathways

Under light illumination, it is usually considered that photocatalytic oxidations of organics such as volatile organic compounds over semiconductors are driven by the transfer of photogenerated carriers. Some studies also proposed that the photocatalytic oxidations might take place according to the light-assisted Mars–van Krevelen (MvK) pathway that involved the participation of lattice oxygens under aerobic conditions. Based on the concept of the MvK mechanism, the current work first gives an elaboration on the light-assisted MvK pathway and its intrinsic difference from the charge carrier transfer pathway. We then examined which one of these two mechanisms is responsible for the the photocatalytic oxidation of formic acid over TiO2. Comprehensive experiments, including apparent kinetics, online electric conductances, vacuum electric conductances, online optical transmittances, and first principle calculations, were carried out to discuss this problem. The results showed that the photocatalytic oxidations of formic acid over TiO2 dominantly follow the charge carrier transfer pathway at both low and elevated temperatures, the light-assisted MvK mechanism could not play a major role, and there was also no transition from the charge carrier transfer to the light-assisted MvK mechanism with an increase of reaction temperature

Copper as an antimicrobial agent: recent advances

From its uses in ancient civilisations, copper has an established history as an antimicrobial agent. Extensive research has determined the efficacy and mechanism of copper's antimicrobial activity against microorganisms. The process is multifaceted with the main mechanism of bactericidal activity being the generation of reactive oxygen species (ROS), which irreversibly damages membranes. Copper ions released from surfaces lead to RNA degradation and membrane disruption of enveloped viruses. For fungi, the mechanism involves the physical deterioration of the membrane and copper ion influx. Due to variations in the experimental parameters, it is difficult to compare studies directly. In this review article, we outline the importance of the experimental conditions currently employed and how they bear little resemblance to real-world conditions. We endorse previous recommendations calling for an update to industrial standard tests

Slippery Liquid Infused Porous TiO₂/SnO₂ Nanocomposite Thin Films via Aerosol Assisted Chemical Vapor Deposition with Anti-Icing and Fog Retardant Properties

Exceptional anti-icing and antifogging devices have been synthesized through combination of micro- and/or nanoscale hierarchical thin films followed by a modification with a surface lubricant. Aerosol assisted chemical vapor deposition (AACVD) of single source titanium and tin precursors generated titanium dioxide (TiO2)/tin dioxide (SnO2) composite thin films. Variation in solvent type and/or combination notably impacted on the resulting intricate surface morphologies, which, upon Krytox lubricant modification, generated slippery liquid infused porous surfaces (SLIPS). The surface topography had a profound effect on the degree of surface ice and fog accumulation. The highest functioning films comprised of hybrid spherical/flowery surface structures generated using a mixed ethyl acetate/dichloromethane solvent system. These films retarded ice formation for >30 min at -10 °C and maintained a high level of sample transparency upon suspension above a heated water bath

Cocaine by-product detection with metal oxide semiconductor sensor arrays

A range of n-type and p-type metal oxide semiconductor gas sensors based on SnO2 and Cr2O3 materials have been modified with zeolites H-ZSM-5, Na-A and H–Y to create a gas sensor array able to successfully detect a cocaine by-product, methyl benzoate, which is commonly targeted by detection dogs. Exposure to vapours was carried out with eleven sensors. Upon data analysis, four of these that offered promising qualities for detection were subsequently selected to understand whether machine learning methods would enable successful and accurate classification of gases. The capability of discrimination of the four sensor array was assessed against nine different vapours of interest; methyl benzoate, ethane, ethanol, nitrogen dioxide, ammonia, acetone, propane, butane, and toluene. When using the polykernel function (C = 200) in the Weka software – and just five seconds into the gas injection – the model was 94.1% accurate in successfully classifying the data. Although further work is necessary to bring the sensors to a standard of detection that is competitive with that of dogs, these results are very encouraging because they show the potential of metal oxide semiconductor sensors to rapidly detect a cocaine by-product in an inexpensive way