Emissions from a modern log wood masonry heater and wood pellet boiler : Composition and biological impact on air-liquid interface exposed human lung cancer cells

The consumption of wood fuel is markedly increasing in developing and industrialized countries. Known side effects of wood smoke inhalation manifest in proinflammatory signaling, oxidative stress, DNA damage and hence increased cancer risk. In this study, the composition and acute biological impact of emissions of state-of-the-art wood combustion compliances: masonry heater (MH) and pellet boiler (PB) were investigated. Therefore A549 cells were exposed to emission aerosols in an automated air-liquid interface exposure station followed by cytotoxicity, transcriptome and proteome analyses. In parallel, aerosols were subjected to a chemical and physical haracterization. Compared to PB, the MH combustion at the same dilution ratio resulted in a 3-fold higher particle mass concentration (PM2.5) and deposited dose (PB: 27 $\pm$ 2 ng/cm2, MH; 73 $\pm$ 12 ng/cm2). Additionally, the MH aerosol displayed a substantially larger concentration of aldehydes, polycyclic aromatic hydrocarbons (PAH) or oxidized PAH. Gene ontology analysis of transcriptome of A549 cells exposed to MH emissions revealed the activation of proinflammatory response and key signaling cascades MAP kinase and JAK-STAT. Furthermore, CYP1A1, an essential enzyme in PAH metabolism, was induced. PB combustion aerosol activated the proinflammatory marker IL6 and different transport processes. The proteomics data uncovered induction of DNA damage-associated proteins in response to PB and DNA doublestrand break processing proteins in response to MH emissions. Taking together, the MH produces emissions with a higher particle dose and more toxic compounds while causing only mild biological responses. This finding points to a significant mitigating effect of antioxidative compounds in MH wood smoke

Software Sustainability: Research and Practice from a Software Architecture Viewpoint

Context: Modern societies are highly dependent on complex, large-scale, software-intensive systems that increasingly operate within an environment of continuous availability, which is challenging to maintain and evolve in response to the inevitable changes in stakeholder goals and requirements of the system. Software architectures are the foundation of any software system and provide a mechanism for reasoning about core software quality requirements. Their sustainability – the capacity to endure in changing environments – is a critical concern for software architecture research and practice. Problem: Accidental software complexity accrues both naturally and gradually over time as part of the overall software design and development process. From a software architecture perspective, this allows several issues to overlap including, but not limited to: the accumulation of technical debt design decisions of individual components and systems leading to coupling and cohesion issues; the application of tacit architectural knowledge resulting in unsystematic and undocumented design decisions; architectural knowledge vaporisation of design choices and the continued ability of the organization to understand the architecture of its systems; sustainability debt and the broader cumulative effects of flawed architectural design choices over time resulting in code smells, architectural brittleness, erosion, and drift, which ultimately lead to decay and software death. Sustainable software architectures are required to evolve over the entire lifecycle of the system from initial design inception to end-of-life to achieve efficient and effective maintenance and evolutionary change. Method: This article outlines general principles and perspectives on sustainability with regards to software systems to provide a context and terminology for framing the discourse on software architectures and sustainability. Focusing on the capacity of software architectures and architectural design choices to endure over time, it highlights some of the recent research trends and approaches with regards to explicitly addressing sustainability in the context of software architectures. Contribution: The principal aim of this article is to provide a foundation and roadmap of emerging research themes in the area of sustainable software architectures highlighting recent trends, and open issues and research challenges

Toxicological characterization of particulate emissions from straw, <i>Miscanthus</i>, and poplar pellet combustion in residential boilers

<p>Wood pellets have been used in domestic heating appliances for three decades. However, because the share of renewable energy for heating will likely rise over the next several years, alternative biomass fuels, such as short-rotation coppice or energy crops, will be utilized. We tested particulate emissions from the combustion of standard softwood pellets and three alternative pellets (poplar, <i>Miscanthus</i> sp., and wheat straw) for their ability to induce inflammatory, cytotoxic, and genotoxic responses in a mouse macrophage cell line. Our results showed clear differences in the chemical composition of the emissions, which was reflected in the toxicological effects. Standard softwood and straw pellet combustion resulted in the lowest PM₁ mass emissions. <i>Miscanthus</i> sp. and poplar combustion emissions were approximately three times higher. Emissions from the herbaceous biomass pellets contained higher amounts of chloride and organic carbon than the emissions from standard softwood pellet combustion. Additionally, the emissions of the poplar pellet combustion contained the highest concentration of metals. The emissions from the biomass alternatives caused significantly higher genotoxicity than the emissions from the standard softwood pellets. Moreover, straw pellet emissions caused higher inflammation than the other samples. Regarding cytotoxicity, the differences between the samples were smaller. Relative toxicity was generally highest for the poplar and <i>Miscanthus</i> sp. samples, as their emission factors were much higher. Thus, in addition to possible technical problems, alternative pellet materials may cause higher emissions and toxicity. The long-term use of alternative fuels in residential-scale appliances will require technological developments in both burners and filtration.</p> <p>Copyright © 2016 American Association for Aerosol Research</p

Genotoxicity.

<p>DNA fragmentation in THP-1 cells after a 24 h exposure to four doses (25, 75, 150 and 200 μg/ml) of PM₁ samples from the combustion of three different wood logs and wood pellets expressed as percentage of DNA in the tail. Each bar represents the average of four independent experiments with 100 analyzed cells/assay + SEM of the experimental averages. Asterisks indicate statistical significance from blank control, <b>a</b> indicates significance from the birch log PM₁ sample, <b>b</b> indicates significance from the beech log PM₁ sample, <b>c</b> indicates significance from the spruce log PM₁ sample, <b>d</b> indicates significance from the pellet combustion PM₁ sample.</p

Oxidative stress.

<p>Oxidative stress assessed with the DCF-assay after a 24 h exposure of three different cell culture setups (A549 and THP-1 monocultures and A549/THP-1 co-culture) to four doses (25, 75, 150 and 200 μg/ml) of particulate samples from the combustion of three different wood logs and wood pellets. Each bar represents the average of eight experiments. Whiskers indicate the standard error of the mean (SEM), asterisks indicate significance from blank control. <b>a</b> indicates significance from the birch log PM₁ sample, <b>b</b> indicates significance from the beech log PM₁ sample, <b>c</b> indicates significance from the spruce log PM₁ sample, <b>d</b> indicates significance from the pellet combustion PM₁ sample. <b>§</b> indicates significance from the A549 monoculture, <b>#</b> indicates significance from the THP-1 monoculture, <b>$</b> indicates significance from the A549/THP-1 co-culture.</p