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Hollow-core 3D printing (HC3DP) proposes a new method for the production of lightweight, material-efficient thermoplastic 3D printed elements. This new fabrication approach promises material savings of 50-80%, while increasing the extrusion rate significantly (factor 10). This development pushes HC3DP to a similar fabrication speed as high-resolution concrete 3D printing. However, fundamental research on printing features enabled by this novel 3D printing approach is missing. Therefore, this article investigates printing with user-controlled bead dimensions (same nozzle, different size). It is showcased that the size of the extruded cross-section is determined by the positive air pressure used to inflate the beads. Multiple samples are printed, changing the layer height and width significantly without making changes to the hardware setup. Sections of 3DP samples are analyzed and the parameters of 3DP beads are determined. Furthermore, a set of bespoke 3D printed nozzles is introduced to subdivide the HC3DP beads into distinct areas. So far only regular beads, such as hollow tubes, have been used for 3D printing. Samples of those bespoke sections are analyzed to investigate their behavior when used for 3D printing. Finally, large-scale 3D printing experiments are conducted to investigate how printing features like bridging, cantilevering, or nonplanar 3D printing can be manufactured with hollow extrusion beads. In summary, this article provides insights into the fundamental 3D printing behaviors of HC3DP, showcases new design possibilities with bespoke and variable cross-sections, and finally proposes new research trajectories based on the findings presented., (Copyright 2024, Mary Ann Liebert, Inc., publishers.)

The architecture, engineering, and construction industry is undergoing a significant shift, steering buildings away from resource-intensive processes toward becoming instruments for climate mitigation. In this transformative landscape, integrating circular bio-based alternatives and reducing emissions through biotechnological and enzymatic processes have significant potential. Specifically, mycelium-bound composites have emerged as renewable alternatives for new materials and added-value wood products. Despite their numerous advantages, integrating these materials into current engineering practices presents challenges deriving from the complex nature of the material´s production process and the transfer from the laboratory to the industrial scale. In this regard, the design and engineering of novel controlled environments are fundamental in maintaining optimal growth conditions during material production. This, in turn, influences the overall material performance and potential use in construction., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). Global Challenges published by Wiley‐VCH GmbH.)

Foam 3D printing in construction is a promising manufacturing approach that aims to reduce the amount of material, hazardous labor, and costs in producing lightweight and insulating building parts that can reduce the operational energy in buildings. Research using cement-free mineral foams derived from industrial waste showed great potential in previous studies that reduced the amount of concrete needed in composite structures. This article collates the latest developments in this line of work. It presents the material system with its principal components and the advanced robotic 3D printing setup with a climate-controlled fabrication chamber. Print path schemes and hybrid fabrication methods combining 3D printing and casting are evaluated. Furthermore, the article discusses the effect of different print path schemes on the thermal insulation and compressive strength performance of printed parts. A full-scale final prototype synthesizes these findings and demonstrates the fabrication of modular, lightweight, and insulating construction elements that can be assembled into monolithic wall structures. The advantages and challenges of this novel approach are elaborated on in the conclusions. Finally, the article presents future advancements required to leverage this research as a scalable construction method that can help address the biggest challenges in building low-carbon and energy-efficient structures., Competing Interests: M.Z. is cofounder and CTO of FenX AG, a company specializing in mineral foams used in this research. All other authors declare that they have no conflict of interest., (© Patrick Bedarf et al. 2024; Published by Mary Ann Liebert, Inc.)

The introduction of robotic arms in additive manufacturing enables the scaling up of three-dimensional (3D) printing processes and the realization of nonplanar path geometries. As a result, novel design potential is unlocked by having control over the layered configuration of paths in the object, and 3D printing becomes viable for architectural applications. However, the various challenges associated with creating feasible nonplanar layered paths for the realization of large-scale objects are hindering their integration in the design process and broad use. This work presents methods that contribute to the flexible and intuitive design of nonplanar layered paths for robotic printing. We focus on the challenges related to the realization of single-shell bifurcating structures, with emphasis on the paths' behavior on the bifurcating moments of the shapes. Our methods are based on the use of design techniques that originate from implicit shape representation and on the detection of critical points on the surface through the lens of distance functions. We present fabricated prototypes printed with nonplanar paths that showcase the possibilities of our methods., Competing Interests: No competing financial interests exist., (© Ioanna Mitropoulou et al. 2022; Published by Mary Ann Liebert, Inc.)

In an increasing effort to address the environmental challenges caused by the currently linear economic paradigm of "produce, use, and discard", the construction industry has been shifting towards a more circular model. A circular economy requires closing of the loops, where the end-of-life of a building is considered more carefully, and waste is used as a resource. In comparison to traditional building materials such as timber, steel and concrete, mycelium-based materials are renewable alternatives that use organic agricultural and industrial waste as a key ingredient for production, and do not rely on mass extraction or exploitation of valuable finite or non-finite resources. Mycelium-based materials have shown their potential as a more circular and economically competitive alternative to conventional synthetic materials in numerous industries ranging from packaging, electronic prototyping, furniture, fashion to architecture. However, application of mycelium-based materials in the construction industry has been limited to small-scale prototypes and architectural installations due to low mechanical properties, lack of standardisation in production methods and material characterisation. This paper aims to review the current state of the art in research and applications of mycelium-based materials across disciplines, with a particular focus on digital methods of fabrication, production, and design. The information gathered from this review will be synthesised to identify key challenges in scaling up applications of mycelium-based materials as load-bearing structural elements in architecture and suggest opportunities and directions for future research.

Concrete is the most used human-made material in the world, and it is responsible for around 8% of the total greenhouse gas emissions worldwide. Hence, efficient concrete construction methods are one of the main foci of research in architecture, civil engineering, and material science. One recent development that promises to achieve this goal is the use of digital fabrication for building components. Most investigations focus on direct extrusion 3D printing with concrete, which has already been covered in several review articles. Conversely, this article reviews a different approach, which focuses on the indirect digital fabrication of concrete through 3D printed formworks. This approach is under investigation for structural and nonstructural, as well as for on- and off-site applications, with a number of projects having already been built, but a comprehensive review of 3D printed formworks has not yet been compiled to synthesize the findings. This article provides a comprehensive map of the state-of-the-art of five different 3D printing technologies used for the fabrication of formworks so far. The aim is to serve as a fundamental reference for future research, provide a basis for consistent language in this field, and support the development of construction standards. The article further discusses the new geometric possibilities with 3D printed formworks and their potential for making concrete construction more sustainable. In addition, the opportunities and challenges of 3D printed formworks are evaluated in the context of other traditional and digital fabrication tools. A synthetic classification in five functional typologies is proposed and illustrated with 30 representative case studies. Finally, the article concludes with a brief reflection on the role of 3D printing in the broader context of formwork innovation and a possible outlook for this technology., Competing Interests: No competing or personal financial interests exist., (© Andrei Jipa et al. 2022; Published by Mary Ann Liebert, Inc.)

This research investigates robotically fabricated polychromatic float glass for architectural applications. Polychromatic glass elements usually require labor-intensive processes or are limited to film applications of secondary materials onto the glass. Previous research employs computer numerical control (CNC) based multi-channel granule deposition to manufacture polychromatic relief glass; however, it is limited in motion, channel control, and design space. To expand the design and fabrication space for the manufacture of mono-material polychromatic glass elements, this paper presents further advancements using a UR robotic arm with an advanced multi-channel dispenser, linear and curved-paths granule deposition, customized color pattern design approaches, and a computational tool for the prediction and rendering of outcomes. A large-scale demonstrator serves as a case study for upscaling. Robotic multi-channel deposition and tailored computational design tools are employed to facilitate a full-scale installation consisting of eighteen large glass panels. Novel optical properties include locally varying color, opacity, and texture filter light and view. The resulting product constructs sublime architectural experiences through light refraction, reflection, color, opacity - beyond mere transparency., Competing Interests: Conflict of interestOn behalf of all authors, the corresponding author states that there is no conflict of interest., (© The Author(s) 2022.)

In order to understand the influence of two dopaminergic signalling pathways, TaqIA rs1800497 (influencing striatal D2 receptor density) and Ser9Gly rs6280 (influencing the striatal D3 dopamine-binding affinity), on saccade generation and psychiatric comorbidities in Parkinson's disease, this study aimed to investigate the association of saccadic performance in hypomanic or impulsive behaviour in parkinsonian patients; besides we questioned whether variants of D2 (A1+/A1-) and D3 (B1+/B1-) receptor polymorphism influence saccadic parameters differently, and if clinical parameters or brain connectivity changes modulate this association in the nigro-caudatal and nigro-collicular tract. Initially, patients and controls were compared regarding saccadic performance and differed in the parameter duration in memory-guided saccades (MGS) and visually guided saccades (VGS) trials ( p  < 0.0001) and in the MGS trial ( p  < 0.03). We were able to find associations between hypomanic behaviour (HPS) and saccade parameters (duration, latency, gain and amplitude) for both conditions [MGS ( p  = 0.036); VGS ( p  = 0.033)], but not for impulsive behaviour. For the A1 variant duration was significantly associated with HPS [VGS ( p  = 0.024); MGS ( p  = 0.033)]. In patients with the B1 variant, HPS scores were more consistently associated with duration [VGS ( p  = 0.005); MGS ( p  = 0.015), latency [VGS ( p  = 0.022)]] and amplitude [MGS ( p  = 0.006); VGS ( p  = 0.005)]. The mediation analysis only revealed a significant indirect effect for amplitude in the MGS modality for the variable UPDRS-ON ( p  < 0.05). All other clinical scales and brain connectivity parameters were not associated with behavioural traits. Collectively, our findings stress the role of striatal D2 and D3 signalling mechanisms in saccade generation and suggest that saccadic performance is associated with the clinical psychiatric state in Parkinson's disease., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2020.)

Human participants made saccadic eye movements to various features in a modified vertical Poggendorff figure, to measure errors in the location of key geometrical features. In one task, subjects ( n  = 8) made saccades to the vertex of the oblique T-intersection between a diagonal pointer and a vertical line. Results showed both a small tendency to shift the saccade toward the interior of the angle, and a larger bias in the direction of a shorter saccade path to the landing line. In a different kind of task (visual extrapolation), the same subjects fixated the tip of a 45° pointer and made a saccade to the implicit point of intersection between pointer and a distant vertical line. Results showed large errors in the saccade landing positions and the saccade polar angle, in the direction predicted from the perceptual Poggendorff bias. Further experiments manipulated the position of the fixation point relative to the implicit target, such that the Poggendorff bias would be in the opposite direction from a bias toward taking the shortest path to the landing line. The bias was still significant. We conclude that the Poggendorff bias in eye movements is in part due to the mislocation of visible target features but also to biases in planning a saccade to a virtual target across a gap. The latter kind of error comprises both a tendency to take the shortest path to the landing line, and a perceptual error that overestimates the vector component orthogonal to the gap.

The magnitude of the Poggendorff bias in perceived collinearity was measured with a 2AFC task and roving pedestal, and was found to be in the region of 6-8deg, within the range of previous estimates. Further measurements dissected the bias into several components: (1) The small (∼1deg) repulsion of the orientation of the pointer from the parallel, probably localized in the part of the line near the intersection (2) A small (<1deg) location bias affecting the intersection of pointers and inducing lines; and (3) A larger (>1deg) bias in the orientation of virtual lines crossing the gap between two parallels, towards the orientation of the parallels, or equivalently (4) An orthogonal bias in actively constructing a virtual line across the gap. We conclude that orientation repulsion by itself is an inadequate explanation of the Poggendorff effect, and that a full explanation must take account of the way in which observers construct virtual lines in visual space in order to carry out elementary geometrical tasks such as extrapolation., (Copyright © 2016. Published by Elsevier Ltd.)

Psychometric sensory discrimination functions are usually modeled by cumulative Gaussian functions with just two parameters, their central tendency (μ) and their slope (1/σ). These correspond to Fechner's "constant" and "variable" errors, respectively. Fechner pointed out that even the constant error could vary over space and time and could masquerade as variable error. We wondered whether observers could deliberately introduce a constant error into their performance without loss of precision. In three-dot vernier and bisection tasks with the method of single stimuli, observers were instructed to favour one of the two responses when unsure of their answer. The slope of the resulting psychometric function was not significantly changed, despite a significant change in central tendency. Similar results were obtained when altered feedback was used to induce bias. We inferred that observers can adopt artificial response criteria without any significant increase in criterion fluctuation. These findings have implications for some studies that have measured perceptual "illusions" by shifts in the psychometric functions of sophisticated observers.

Real lines and illusory contours (ICs) have been reported to either interfere with or facilitate the perception of the other, depending on real line orientation and contrast. Here we investigate contextual effects of real lines on illusory contour perception. Curvature discrimination thresholds of Kanizsa-contours were measured for superimposed real lines of different sub- and suprathreshold contrasts. We find that parallel lines interfere with curvature discrimination at suprathreshold, whereas orthogonal lines interfere at subthreshold contrasts. We did not find stable facilitating effects of lines in any orientation or contrast. These results are discussed in relation to existing physiological and imaging data.