Trees, and their derivative products, have been used by societies around the world for thousands of years. Contemporary construction of tall buildings from timber, in whole or in part, suggests a ...growing interest in the potential for building with wood at a scale not previously attainable. As wood is the only significant building material that is grown, we have a natural inclination that building in wood is good for the environment. But under what conditions is this really the case? The environmental benefits of using timber are not straightforward; although it is a natural product, a large amount of energy is used to dry and process it. Much of this can come from the biomass of the tree itself, but that requires investment in plant, which is not always possible in an industry that is widely distributed among many small producers. And what should we build with wood? Are skyscrapers in timber a good use of this natural resource, or are there other aspects of civil and structural engineering, or large-scale infrastructure, that would be a better use of wood? Here, we consider a holistic picture ranging in scale from the science of the cell wall to the engineering and global policies that could maximise forestry and timber construction as a boon to both people and the planet.
This study evaluates the effect of complete nationwide lockdown in 2020 on residential electricity demand across 13 Indian cities and the role of digitalisation using a public smart meter dataset. We ...undertake a data-driven approach to explore the energy impacts of work-from-home norms across five dwelling typologies. Our methodology includes climate correction, dimensionality reduction and machine learning-based clustering using Gaussian Mixture Models of daily load curves. Results show that during the lockdown, maximum daily peak demand increased by 150–200% as compared to 2018 and 2019 levels for one room-units (RM1), one bedroom-units (BR1) and two bedroom-units (BR2) which are typical for low- and middle-income families. While the upper-middle- and higher-income dwelling units (i.e., three (3BR) and more-than-three bedroom-units (M3BR)) saw night-time demand rise by almost 44% in 2020, as compared to 2018 and 2019 levels. Our results also showed that new peak demand emerged for the lockdown period for RM1, BR1 and BR2 dwelling typologies. We found that the lack of supporting socioeconomic and climatic data can restrict a comprehensive analysis of demand shocks using similar public datasets, which informed policy implications for India's digitalisation. We further emphasised improving the data quality and reliability for effective data-centric policymaking.
-Lockdown caused shifts in daily peak demand across residential units in 13 cities in India-Daily peak demand increase by 150–200% due to lockdown in households with one or two rooms-Work-from-home effects identified through emerging peak demand across typologies-Demonstrated the need for robust public data quality as digitalisation policy for India
The strength of plants Shah, Darshil U.; Reynolds, Thomas P.S.; Ramage, Michael H.
Journal of experimental botany,
07/2017, Letnik:
68, Številka:
16
Journal Article
Recenzirano
Odprti dostop
From the stems of agricultural crops to the structural trunks of trees, studying the mechanical behaviour of plant stems is critical for both commerce and science. Plant scientists are also ...increasingly relying on mechanical test data for plant phenotyping. Yet there are neither standardized methods nor systematic reviews of current methods for the testing of herbaceous stems. We discuss the architecture of plant stems and highlight important micro- and macrostructural parameters that need to be controlled and accounted for when designing test methodologies, or that need to be understood in order to explain observed mechanical behaviour. Then, we critically evaluate various methods to test structural properties of stems, including flexural bending (two-, three-, and four-point bending) and axial loading (tensile, compressive, and buckling) tests. Recommendations are made on best practices. This review is relevant to fundamental studies exploring plant biomechanics, mechanical phenotyping of plants, and the determinants of mechanical properties in cell walls, as well as to application-focused studies, such as in agro-breeding and forest management projects, aiming to understand deformation processes of stem structures. The methods explored here can also be extended to other elongated, rod-shaped organs (e.g. petioles, midribs, and even roots).
•Mechanical characterisation of bleached and semi-caramelised laminated bamboo.•Thermal treatment processing methods have an effect on the mechanical properties.•Engineered bamboo has mechanical ...properties comparable to timber.
Engineered bamboo is increasingly explored as a material with significant potential for structural applications. The material is comprised of raw bamboo processed into a laminated composite. Commercial methods vary due to the current primary use as an architectural surface material, with processing used to achieve different colours in the material. The present work investigates the effect of two types of processing methods, bleaching and caramelisation, to determine the effect on the mechanical properties. A comparison to other engineered bamboo and timber products is also presented. The results of the study indicate that processing does affect the mechanical properties of engineered bamboo products. Areas in need of further research are also identified for thermally treated bamboo to be used in structural applications.
Inspired by biological systems, we report a supramolecular polymer–colloidal hydrogel (SPCH) composed of 98 wt % water that can be readily drawn into uniform (∼6-μm thick) “supramolecular fibers” at ...room temperature. Functionalized polymer-grafted silica nanoparticles, a semicrystalline hydroxyethyl cellulose derivative, and cucurbit8uril undergo aqueous self-assembly at multiple length scales to form the SPCH facilitated by host–guest interactions at the molecular level and nanofibril formation at colloidal-length scale. The fibers exhibit a unique combination of stiffness and high damping capacity (60–70%), the latter exceeding that of even biological silks and cellulose-based viscose rayon. The remarkable damping performance of the hierarchically structured fibers is proposed to arise from the complex combination and interactions of “hard” and “soft” phases within the SPCH and its constituents. SPCH represents a class of hybrid supramolecular composites, opening a window into fiber technology through low-energy manufacturing.
The building and construction sector accounts for around 39% of global carbon dioxide emissions and remains a hard-to-abate sector. We use a data-driven analysis of global high-level climate action ...on emissions reduction in the building sector using 256,717 English-language tweets across a 13-year time frame (2009-2021). Using natural language processing and network analysis, we show that public sentiments and emotions on social media are reactive to these climate policy actions. Between 2009-2012, discussions around green building-led emission reduction efforts were highly influential in shaping the online public perceptions of climate action. From 2013 to 2016, communication around low-carbon construction and energy efficiency significantly influenced the online narrative. More significant interactions on net-zero transition, climate tech, circular economy, mass timber housing and climate justice in 2017-2021 shaped the online climate action discourse. We find positive sentiments are more prominent and recurrent and comprise a larger share of the social media conversation. However, we also see a rise in negative sentiment by 30-40% following popular policy events like the IPCC report launches, the Paris Agreement and the EU Green Deal. With greater online engagement and information diffusion, social and environmental justice topics emerge in the online discourse. Continuing such shifts in online climate discourse is pivotal to a more just and people-centric transition in such hard-to-decarbonise sectors.
•Angle-ply laminates can extend current range of laminated bamboo products.•Mechanical properties of laminated bamboo are sensitive to loading direction.•Composite laminate theory accurately predicts ...behaviour of engineered bamboo.•Optimum ply configuration can be selected for a structure with a known stress field.
Currently, only two forms of laminated bamboo are commercially available as structural materials: unidirectional beams and boards, and cross-laminated boards. As a natural quasi-unidirectional composite, the lamination of bamboo into plies with specific orientations would allow the design and manufacture of a family of multi-axial composite laminates with unique properties. In this study, we test the tensile mechanical properties of single- and two-ply laminated bamboo at various off-axis loading angles and laminate configurations. The data is then compared to micro-mechanical models for predicting modulus and strength of composite laminates. On the basis of our analyses, we believe there is significant scope to extend the current range of laminated bamboo products to include angle-ply laminates. Moreover, we demonstrate that composite laminate theory is applicable to this natural composite and may be used for design of products and structures.
Spider silk is a fascinating material, combining high strength and elasticity that outperforms most synthetic fibers. Another intriguing feature of spider silk is its ability to “supercontract,” ...shrinking up to 50% when exposed to water. This is likely on account of the entropy‐driven recoiling of secondary structured proteins when water penetrates the spider silk. In contrast, humidity‐driven contraction in synthetic fibers is difficult to achieve. Here, inspired by the spider silk model, a supercontractile fiber (SCF), which contracts up to 50% of its original length at high humidity, comparable to spider silk, is reported. The fiber exhibits up to 300% uptake of water by volume, confirmed via environmental scanning electron microscopy. Interestingly, the SCF exhibits tunable mechanical properties by varying humidity, which is reflected by the prolonged failure strain and the reversible damping capacity. This smart supramolecular fiber material provides a new opportunity of fabricating biomimetic muscle for diverse applications.
A spider‐silk‐inspired supramolecular fiber, spun from a hydrogel (98 wt% water) at room‐temperature, is reported, which exhibits water‐induced supercontraction of up to 50%, tunability in mechanical properties with humidity, and high damping capacity of 75%.
Scanning thermal microscopy is a powerful tool for investigating biological materials and structures like bamboo and its cell walls. Alongside nanoscale topographical information, the technique ...reveals local variations in thermal conductivity of this elegant natural material. We observe that at the tissue scale, fibre cells in the scattered vascular tissue would offer preferential pathways for heat transport due to their higher conductivities in both anatomical directions, in comparison to parenchymatic cells in ground tissue. In addition, the transverse orientation offers more resistance to heat flow. Furthermore, we observe each fibre cell to compose of up to ten layers, with alternating thick and thin lamellae in the secondary wall. Notably, we find the thin lamellae to have relatively lower conductivity than the thick lamellae in the fibre direction. This is due to the distinct orientation of cellulose microfibrils within the cell wall layers, and that cellulose microfibrils are highly anisotropic and have higher conductivity along their lengths. Microfibrils in the thick lamellae are oriented almost parallel to the fibre cell axis, while microfibrils in the thin lamellae are oriented almost perpendicular to the cell axis. Bamboo grasses have evolved to rapidly deposit this combination of thick and thin layers, like a polymer composite laminate or cross-laminated timber, for combination of axial and transverse stiffness and strength. However, this architecture is found to have interesting implications on thermal transport in bamboo, which is relevant for the application of engineered bamboo in buildings. We further conclude that scanning thermal microscopy may be a useful technique in plant science research, including for phenotyping studies.
Engineered bamboo is being increasingly explored for structural use in the construction sector. To ensure durability, products such as laminated bamboo undergo essential preservation treatment steps ...during their manufacture. However, the effects of hygro-thermal caramelisation and chemical bleaching, two commonly used treatment procedures in industry, on the surface and interfacial properties of laminated bamboo are not yet known. The latter governs the structural quality of the final product. Our dynamic wettability studies through contact angle measurements revealed lower water contact angles, higher total surface energy and a slightly greater polarity ratio for bleached bamboo in comparison to caramelised and untreated bamboo. In addition, lap-joint shear tests and Weibull reliability analysis established the significantly better adhesive bonding performance of bleached bamboo with all five surveyed adhesives. Our observations are explained through the changes in chemical composition and structure of the raw bamboo material upon treatment, where changes in caramelised and bleached bamboo are dominated by hemicellulose degradation and lignin degradation, respectively. The bleaching process is conclusively identified as having favourable effects on bond strength of the glue line.
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