Silica thin-films from perhydropolysilazane for the protection of ancient glass

Silica coatings from polysilazane precursors were prepared to protect ancient glass from weathering. Polysilazane can be converted to silica by simple exposition to air or basic vapours and the properties of the synthesized film make this precursor a valuable choice to obtain solid, crack-free, highly adhesive and protective coatings. The coating is prepared starting from a Perhydropolysilazane precursor (20% PHPS in n-butyl ether) that allows to achieve high-quality thin-films of silica at room temperature. The obtained films are uncoloured, even in absence of strong heat-treatment. Perhydropolysilazane (PHPS) is a polymer of [-SiH2-NH-SiH2-]n units. When deposited on a soda-lime microscope slide, it reacts with atmospheric moisture (Si-H and Si-NH bonds are hydrolysed to Si-O) and a silica film is produced. The conversion to silica is completed in about 2.5 hours, using vapours of a 10 mol L-1 ammonia solution. The reaction is promoted with the application of a weak heat-treatment (45-50 \ub0C), achievable using as heater a common tungsten filament lamp. The reaction of PHPS with atmospheric moisture produces a migration phenomenon of the mobile ions from the soda-lime glass to the film (in particular sodium, calcium and magnesium). The characteristics of the migration process vary according to the concentration of the precursor solution and the thickness of the film. Laboratory samples have been investigated by optical microscopy and surface techniques: XPS and SIMS. Preliminary evidences, obtained through the laser scanning confocal microscope (LEXT), on the application of such coatings at the surface of ancient stained glass are also discussed

WO3-decorated ZnO nanostructures for light-activated applications

In the present work, a two-step vapor-phase route was implemented for the tailored design of ZnO\u2013WO3 nanoheterostructures supported on fluorine-doped tin oxide (FTO) substrates. Under optimized conditions, the sequential use of chemical vapor deposition (CVD) and radio frequency (RF)-sputtering for the deposition of zinc and tungsten oxides respectively, resulted in the growth of calyx-like ZnO nanostructures uniformly decorated by a conformal dispersion of low-sized WO3 nanoparticles. The target materials were characterized by means of a multi-technique approach, with particular regard to their structural, compositional, morphological and optical properties. Finally, their photocatalytic performances were preliminarily tested in the abatement of NOX gases (NO and NO2). Due to the unique porous morphology of the ZnO nanodeposit and the high density of ZnO\u2013WO3 heterojunctions, WO3-decorated ZnO revealed appealing De-NOX characteristics in terms of both degradation efficiency and selectivity. Such features, along with the photoinduced superhydrophilicity and self-cleaning properties of the present nanomaterials, candidate them as promising functional platforms for applications in smart windows and building materials for environmental remediation

Lithium niobate micromachining for the fabrication of microfluidic droplet generators

In this paper, we present the first microfluidic junctions for droplet generation directly engraved on lithium niobate crystals by micromachining techniques, preparatory to a fully integrated opto-microfluidics lab-on-chip system. In particular, laser ablation technique and the mechanical micromachining technique are exploited to realise microfluidic channels in T-and cross junction configurations. The quality of both lateral and bottom surfaces of the channels are therefore compared together with a detailed study of their roughness measured by means of atomic force microscopy in order to evaluate the final performance achievable in an optofluidic device. Finally, the microfluidics performances of these water-in-oil droplets generators are investigated depending on these micromachining techniques, with particular focus on a wide range of droplet generation rates

a distributed data acquisition system for nuclear detectors

Nowadays, many examples of data acquisition (DAQ) software for experimental nuclear physics are monolithic processes that run on a computer attached to the DAQ hardware. In this article we present a distributed DAQ system developed for the C-BORD project. With our system, we propose a novel approach, in which each task related to the different DAQ parts (acquisition, pre-process, analysis, etc.) runs in a separate process. In particular, the system is composed of a set of servers that exchange information through dedicated communication sockets. Therefore, with this architecture, an important advantage is the possibility to run the processes on different computers to distribute the computational load. The initial tests of the system have been giving excellent results, both in terms of performance (i.e., maximum acquisition rates) and stability. The project entitled "Effective container inspection at BORDer control points" (C-BORD) is funded by the European H2020 programme. Its aim is to develop a comprehensive set of technologies for the generalized non-intrusive inspection (NII) of containers and large-volume freight at the European Union border

Dual Improvement of β‐MnO2 Oxygen Evolution Electrocatalysts via Combined Substrate Control and Surface Engineering

The development of catalysts with high intrinsic activity towards the oxygen evolution reaction (OER) plays a critical role in sustainable energy conversion and storage. Herein, we report on the development of efficient (photo)electrocatalysts based on functionalized MnO2 systems. Specifically, β-MnO2 nanostructures grown by plasma enhanced-chemical vapor deposition on fluorine-doped tin oxide (FTO) or Ni foams were decorated with Co3O4 or Fe2O3 nanoparticles by radio frequency sputtering. Upon functionalization, FTO-supported materials yielded a performance increase with respect to bare MnO2, with current densities at 1.65 V vs. the reversible hydrogen electrode (RHE) up to 3.0 and 3.5 mA/cm2 in the dark and under simulated sunlight, respectively. On the other hand, the use of highly porous and conductive Ni foam substrates enabled to maximize cooperative interfacial effects between catalyst components. The best performing Fe2O3/MnO2 system provided a current density of 17.9 mA/cm2 at 1.65 V vs. RHE, an overpotential as low as 390 mV, and a Tafel slope of 69 mV/decade under dark conditions, comparing favorably with IrO2 and RuO2 benchmarks. Overall, the control of β-MnO2/substrate interactions and the simultaneous surface property engineering pave the way to an efficient energy generation from abundant natural resources

The experience of regular exercise participation for women moving into their middle years : its nature, meaning and its benefits

This study added to the limited research on positive aspects of the human condition. It highlighted the perspective that women in western society recognise that there are wider health benefits to be taken from exercise than science suggests. Whilst this study acknowledged the customary fragmentary view, it took a holistic approach to exploring the nature and meaning of regular participation in exercise from the perspective of 41 women aged 30 to 50 years. This qualitative study included the views of regular participants in facility based and non-facility based exercise, along with the views of exercise instructors and the researcher. The study was contextualised within the traditional theories of related disciplines, namely health, women's studies, and exercise science. Also it was founded on the fitness industry's perspective on its service provision and its instructor training. Theory was compared with the experiences of a sector of the female population who, despite all the accepted calls on their time and energy, consistently maintained regular involvement in exercise. The study provided a holistic perspective on the nature, meaning and benefits of regular participation in exercise. Semi-structured interviews and focus groups were utilised in the data gathering process. In each case, the process consisted of a series of questions designed to explore a subjective perception of experience in accordance with the Neuro-Logical Levels process, a model from within the field of Neuro-Linguistic Programming (Dilts, 1990; Dilts, Hallbom and Smith, 1990; O'Connor and Seymour, 1995). This model acknowledges that behaviours and actions, witnessed on a surface level, are driven by internal systems, including personal beliefs and identity structures. It was utilised as an exploratory technique to identify unconscious triggers for behaviour. The use of this process in the interviews facilitated individual exploration of the research topic at increasingly deep levels of awareness. Focus groups demonstrated a consensus on, as well as further individual differences in, the beliefs, attitudes, experiences and feelings of the participants as they arose from the interactive context. The heuristic methodology utilised in the analysis and presentation of the data offered a holistic, person-centred and reflective perspective on the nature, meaning and benefits of exercise (Moustakas, 1990). Individual and exemplary portraits depicted the experience and personal meaning of exercise as it emerged from the data. Composite depictions conveyed the nature of exercise participation from the perspectives of participants and instructors. The researcher's involvement in the complete study facilitated the emergence of a creative synthesis of the essence of exercise. Exercise provided emotional and spiritual gains that extended beyond the traditional lifestyle benefits. Individuals indicated a range of 'special' qualities in exercise, along with benefits to the mind. They noted unique personal benefits and enhanced interpersonal relationships in all spheres of life. Regular participation in exercise greatly enhanced the lives of those involved and contributed to an individual and collective evolutionary process. Effective exercise delivery consisted of interactional and motivational elements beyond the scientific and mechanistic topics traditionally recognised in instructor training programmes and was founded on empathy, facilitation, passion, love and positive energy.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Surface Functionalization of Grown-on-Tip ZnO Nanopyramids: From Fabrication to Light-Triggered Applications

We report on a combined chemical vapor deposition (CVD)/radio frequency (RF) sputtering synthetic strategy for the controlled surface modification of ZnO nanostructures by Ti-containing species. Specifically, the proposed approach consists in the CVD of grown-on-tip ZnO nanopyramids, followed by titanium RF sputtering under mild conditions. The results obtained by a thorough characterization demonstrate the successful ZnO surface functionalization with dispersed Ti-containing species in low amounts. This phenomenon, in turn, yields a remarkable enhancement of photoactivated superhydrophilic behavior, self-cleaning ability, and photocatalytic performances in comparison to bare ZnO. The reasons accounting for such an improvement are unravelled by a multitechnique analysis, elucidating the interplay between material chemico-physical properties and the corresponding functional behavior. Overall, the proposed strategy stands as an amenable tool for the mastering of semiconductor-based functional nanoarchitectures through <i>ad hoc</i> engineering of the system surface