Photo-initiated chemical vapor deposition of thin films using syngas for the functionalization of surfaces at room temperature and near-atmospheric pressure

Hydrophilic and hydrophobic thin films have been deposited onto flat metallic substrates through photo-initiated chemical vapor deposition (PICVD), using syngas as a precursor, and affordable UVC germicidal lamps as a source of light. This study is the first experimental investigation of what has been previously concluded to be the potential solution to the current widespread nanoparticle functionalization problem. This study addresses the current limiting factor, namely the cost issue, by using simple gas precursors, using an affordable initiation source and operating under normal conditions. This approach differs from the current approaches which use expensive solvents as precursors, energy consuming-sources of initiation (e.g. high temperature, plasma and VUV) and operate under high vacuum and/or high temperatures. While the current paradigm is to target the peak absorption of a molecule, the present study indicates that long chain polymerized products can be formed from off-peak wavelengths. It has been found that photo-initiated deposition occurs and that a wide range of water contact angles, from 5° to 118°, can be obtained by manipulating the experimental conditions. A multilinear empirical model has been derived, and it predicts fairly well the contact angles obtained as a function of the different experimental parameters

Charge effect of superparamagnetic iron oxide nanoparticles on their surface functionalization by photo-initiated chemical vapour deposition

Diverse applications of superparamagnetic iron oxide nanoparticles (SPIONs) in the chemical and biomedical industry depend on their surface properties. In this paper, we investigate the effect of initial surface charge (bare, positively and negatively charged SPIONs) on the resulting physicochemical properties of the particles following treatment through photo-initiated chemical vapour deposition (PICVD). Transmission electron microscopy shows a nanometric polymer coating on the SPIONs and contact angle measurements with water demonstrate that their surface became non-polar following functionalization using PICVD. FTIR and XPS data confirm the change in the chemical composition of the treated SPIONs. Indeed, XPS data reveal an initial charge-dependent increase in the surface oxygen content in the case of treated SPIONs. The O/C percentage ratios of the bare SPIONs increase from 1.7 to 1.9 after PICVD treatment, and decrease from 1.7 to 0.7 in the case of negatively charged SPIONs. The ratio remains unchanged for positively charged SPIONs (1.7). This indicates that bare and negatively charged SPIONs showed opposite preference for the oxygen or carbon attachment to their surface during their surface treatment. These results reveal that both the surface charge and stereochemical effects have determinant roles in the polymeric coating of SPIONs with PICVD. Our findings suggest that this technique is appropriate for the treatment of nanoparticles

One-step processing of highly viscous multiple Pickering emulsions

ABSTRACT: Hypothesis Solid-stabilized Pickering emulsions have attracted a lot of attention recently due to their surfactant-free character, and exceptional stability. At the moment, how the viscosities of the liquid phases impact the processing of Pickering emulsions remain to be clearly understood – it is however an important parameter to consider when developing chemical engineering processes employing these multiphase liquids. Our first assumption was that the amount of emulsified dispersed phase would drastically decrease as viscosity increases. Experiments and findings In this work, we demonstrate that double water-in-oil-in-water (W/O/W) Pickering emulsions are obtained in a single processing step when using very high viscosity silicone oils (≥10,000 cSt) and a single type of sub-μm silica particles modified with two grafted silanes and sodium alginate. The formation of water sub-inclusions proceeds via a phase-inversion mechanism. These sub-inclusions are subsequently stabilized and retained in the oil phase due to its viscosity, limiting sub-inclusions mobility, and the presence of adsorbed particles forming dense layers at oil-water interfaces, acting as barriers. The process we present is simple, requires a minimum number of components, and allows the preparation of multiple emulsions which could then be used to efficiently protect and/or transport a variety of sensitive encapsulated compounds

Combined extraction and functionalization of low-cost nanoparticles from municipal solid waste fly ash through PICVD

While nanoparticles have been the focus of intensive research for several years as a result of their remarkable surface-driven properties, they remain, for the most part, stuck in the lab. This unfortunate fact can be explained by three main reasons: (1) most studies have not dealt with the scalability and cost issues related to the use of nanomaterials on an industrial scale; (2) a great deal of focus has been applied to “outlier” results that promise far more than can be delivered; and (3) very little attention has been given to surface engineering. We propose to curtail the significant cost issue by extracting low-cost, low-grade nanoparticles that are appropriate for several applications from a ubiquitous and abundant feed stock: fly ash from municipal solid waste (MSW) incineration. The novel technique we apply is capable of both extraction and functionalization of the nanoparticles present in this undervalued waste stream using photo-initiated chemical vapor deposition (PICVD). By setting functionalization conditions to favor hydrophilic surface properties, the treated ash can readily be dispersed in a polar solvent such as water: larger particulates then settle out of suspension, while the lighter nanoparticles remain in the supernatant and are ready for use. While it is true that this method yields low-grade nanoparticles (polydisperse and multi-composite), these can be used in a variety of applications where composition is less crucial, such as increasing the thermal conductivity of composites and nanofluids

Improving atmospheric water harvesting in carbon-based sorbents through CO₂ activation

ABSTRACT: Atmospheric water harvesting (AWH) can serve as an alternative fresh water source in regions with scarce access to drinking water. While many techniques are geographically or seasonally limited, sorbent-based AWH shows the potential for wider application. Low-cost, carbon-based sorbents named nanoporous sponges (NPS) are recently developed, exhibiting fast and repeatable water uptake of 0.14 g g⁻¹ at 90% relative pressure. While useful from a cost and daily water yield point of view, there is room for improvement. This article presents an improved production process combining pyrolysis and activation under CO₂ in a single step, yielding improved NPS capable of reproducibly reaching a water uptake of 0.47 g g⁻¹ at 95% relative pressure while maintaining fast sorption rates. The NPS show significant endurance and are able to maintain stable performance over numerous humidity cycles. An unexpected time-dependant sorption behavior is also identified for NPS produced with a modified synthesis formulation, due to an increase in sodium carbonate residual content

Catching Element Formation In The Act

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions.Comment: 14 pages including 3 figure

Neoplasia maligna da mama em mulheres no Brasil: aspectos epidemiológicos, diagnóstico e tratamento

This article aims to evaluate the epidemiological aspects, diagnosis and treatment of patients with malignant breast neoplasia. This is an integrative review using the BVS, SciELO, LILACS and PubMed as databases over the last 5 years. 272 articles on the topic were evaluated with an emphasis on a synthesis of the most recent knowledge and greater scientific consistency. Breast cancer must be approached by a multidisciplinary team aiming at comprehensive treatment of the patient. It is concluded that this neoplasm stands out as one of the most serious public health problems in Brazil. Early diagnosis of breast cancer, aiming to evaluate the best treatment possibilities for these young patients, can have fewer impacts on their personal and social lives.Este artigo tem por objetivo avaliar os aspectos epidemiológicos, diagnóstico e tratamento das pacientes com neoplasia maligna da mama. Trata-se de uma revisão integrativa utilizando como base de dados a BVS, a SciELO, o LILACS e o PubMed, nos últimos 5 anos. Foram avaliados 272 artigos sobre o tema com ênfase em uma síntese dos conhecimentos mais recentes e de maior consistência científica. O câncer de mama deve ser abordado por uma equipe multidisciplinar visando ao tratamento integral da paciente. Conclui-se que essa neoplasia destaca-se como um dos mais graves problemas de saúde pública do Brasil. O diagnóstico precoce do câncer de mama, visando avaliar as melhores possibilidades de tratamento para essas pacientes jovens, pode proporcionar menores impactos na sua vida pessoal e social

Surface engineering of wood substrates to impart barrier properties: a photochemical approach

In this study, sugar maple and white pine, two species of wood commonly used in indoor and outdoor applications, were treated by photo-initiated chemical vapor deposition to impart barrier properties. After treatment, wood wettability decreased significantly, as evidenced by water contact angle measurements (from 50° to 113° for sugar maple and 87° to 172° for white pine). Further, beyond being able to repel water, the coating shows the ability to breathe, evidenced by standardized vapor sorption tests. However, accelerated weathering via ASTM G155 testing determined that the treatment could not protect the wood from photo-degradation, or retain its properties post-weathering. This treatment could therefore be best suited for wood pre-treatment in combination with other coatings