119092 research outputs found
Sort by
Engineering of a Plant Isoprenyl Diphosphate Synthase for Development of Irregular Coupling Activity
No full textWe performed mutagenesis on a regular isoprenyl diphosphate synthase (IDS), neryl diphosphate synthase from Solanum lycopersicum (Sl NPPS), that has a structurally related analogue performing non‐head‐to‐tail coupling of two dimethylallyl diphosphate (DMAPP) units, lavandulyl diphosphate synthase from Lavandula x intermedia (Li LPPS). Wild‐type Sl NPPS catalyses regular coupling of isopentenyl diphosphate (IPP) and DMAPP in cis ‐orientation resulting in the formation of neryl diphosphate. However, if the enzyme is fed with DMAPP only, it is able to catalyse the coupling of two DMAPP units and synthesizes two irregular monoterpene diphosphates; their structures were elucidated by the NMR analysis of their dephosphorylation products. One of the alcohols is lavandulol. The second compound is the trans ‐isomer of planococcol, the first example of an irregular cyclobutane monoterpene with this stereochemical configuration. The irregular activity of Sl NPPS constitutes 0.4 % of its regular activity and is revealed only if the enzyme is supplied with DMAPP in the absence of IPP. The exchange of asparagine 88 for histidine considerably enhanced the non‐head‐to‐tail coupling. While still only observed in the absence of IPP, irregular activity of the mutant reaches 13.1 % of its regular activity. The obtained results prove that regular IDS are promising starting points for protein engineering aiming at the development of irregular activities and leading to novel monoterpene structures
A semi‐analytical approach for the efficient predicition of thermally induced interface crack initiation at bi‐material free edges
No full textIn the present study, thermally induced interlaminar crack initiation emanating from the free edge of a bi‐material junction is investigated by the example of a uniformly cooled epoxy‐glass bi‐material specimen taken from literature. For this purpose, the coupled stress and energy criterion within the framework of finite fracture mechanics is applied. Interlaminar stresses and energy dissipation due to crack onset are determined efficiently using the semi‐analytical scaled boundary finite element method (SBFEM). Moreover, the effect of the layer thicknesses on crack initiation is studied. For this purpose, dimensional analyses yield simple scaling laws for interlaminar stresses and energy dissipation with respect to the layer thickness such that only few model evaluations are required. The obtained results are compared to a finite element reference solution. For validation purposes, a cohesive zone model is applied additionally. Finally, the obtained predictions are compared to experimental findings from literature
3D‐Printing with steel of a bolted connection
No full textAdditive Manufacturing seems promising for the steel construction industry, especially for small components with complex shapes. With Wire‐and‐Arc‐Additive‐Manufacturing (WAAM) a process was found which is fast and cheap compared to other Additive Manufacturing processes for metals. Furthermore, arc‐welding is well known in steel construction industry.
Bolted head plates are a common connection. Although they are relatively easy to produce, they are uneconomical in load transfer due to straining of the plates which are subject to bending. This type of connection is predestined for Additive Manufacturing. Rethinking the structure by taking into account the potentials of Additive Manufacturing brings a clear advantage compared to the conventional production. Thus, with a material saving of 60 % the same load capacity of the original flat head plate can be achieved.
The paper shows how the new production process WAAM can significantly change the shape of structures on the example of a bolted head plate. Therefore, all steps from the original design to the manufactured structure are demonstrated, including the structure finding by using topology optimization, the manufacturing with different parameters and a first testing of the manufactured structures
Ferrofluid--Based Bioink for 3D Printed Skeletal Muscle Tissues with Enhanced Force and Magnetic Response
No full text3D printing has emerged as a transformative technology in several manufacturing processes, being of particular interest in biomedical research for allowing the creation of 3D structures that mimic native tissues. The process of tissue 3D printing entails the construction of functional, 3D tissue structures. In this article, the integration of ferrofluid consisting of iron oxide nanoparticles into muscle cell-laden bioink is presented to obtain a 3D printed magnetically responsive muscle tissue, i.e., the ferromuscle. Using extrusion-based methods, the seamless integration of biocompatible ferrofluids are achieved to cell-laden hydrogels. The resulting ferromuscle tissue exhibits improved tissue differentiation demonstrated by the increased force output upon electrical stimulation compared to muscle tissue prepared without ferrofluid. Moreover, the magnetic component originating from the iron oxide nanoparticles allows magnetic guidance, as well as good cytocompatibility and biodegradability in cell culture. These findings offer a new versatile fabrication approach to integrate magnetic components into living constructs, with potential applications as bioactuators and for future integration in smart, functional muscle implants
A compact and low‐cost do‐it‐yourself water level meter
No full textGoundwater level measurements underpin most, if not all, hydrogeological studies. While the advent of automatic pressure transducers may give the impression that manual measurements have become less important, this is not the case. They provide much-needed reference data (Rau et al., 2019) and pressure transducers are not generally affordable for everyone. Hence, many measurements are still conducted manually. Most of them are carried out with electric water level tapes (also known as dip meters; Rau et al., 2019). The principle of these tapes is that an electrical circuit is completed at the probe tip upon water contact, triggering a visible and/or audible signal at the tape reel (at ground surface). Despite the simplicity of this concept, these devices often cost several hundred Euros and are not readily available in some parts of the world. A number of textbooks and blogs provide circuit diagrams and build guides (Brassington, 2007; McGill, 2016), but home-made constructions are somewhat hampered by the fact that measuring tapes with integrated wires are difficult to reproduce
High-capacity intercalation-based anodes for solid-state fluoride-ion batteries enabled by the substitution of conductive carbon by metallic copper
No full textFluoride-ion batteries are a promising battery technology to achieve high energy densities exceeding those of traditional lithium-ion batteries. Reports on intercalation-based electrode materials for fluoride-ion batteries have mostly focused on cathode materials, while only a few intercalation-based anode materials have been reported. Their performance was heavily affected by carbon-based reductive side reactions, limiting reversibility and introducing high overpotentials. In this study, we present the successful substitution of carbon by metallic copper in solid-state FIBs, enabling the use of La2NiO3F2, Pr2NiO3F2, Sr2TiO3F2, and Sr3Ti2O5F4 as intercalation-based anode materials by avoiding parasitic side reactions associated with the conductive carbon additive
Ride&Decide: A Participatory Approach to a Serious Game for City Development
No full textPublic participation in urban planning is essential for legitimacy and acceptance but often fails to engage diverse demographics, especially younger citizens. Traditional methods offer limited accessibility and lack engaging ways to visualize infrastructure changes. This paper presents a geo-based serious game approach, developed through participatory workshops, that immerses players in a 3D digital twin of a real city. Players navigate urban environments, interact with virtual characters, and experience planning scenarios from various mobility perspectives. Integrated feedback mechanics allow for the collection of meaningful feedback. The results highlight the potential of game-based approaches to enhance citizen engagement in urban development
Which effort pays off? Analyzing ideators’ behavioral patterns on corporate ideation platforms
No full textThe challenge of developing high‐quality ideas as the basis of new goods and services is an important topic that coincides with companies’ rapid development of these products. In response, firms increasingly rely on online ideation platforms for ideation contests to optimize their employees’ creative power. This optimization requires a profound understanding of online ideation contests’ underlying mechanisms, specifically the participants’ innovative behavior that contributes to generating, elaborating, and championing ideas based on each ideator's effort distribution, namely their behavioral patterns. Our analysis of the ideators’ behavioral patterns and their relationship to idea success consists of two steps. First, we combine contest theory with innovative behavior literature to derive eight types of innovative behavior in online contests—clustered into the three categories idea generation, elaboration, and championing—that represent the ideators’ required efforts to compete in an ideation contest successfully. Second, we use a unique empirical sample, which combines platform and evaluation data of a corporate R&D ideation contest with participants’ survey data, received a few days before the contest's closure, to analyze the relationship between the effort invested in these dimensions and idea success. The results show that more effort does not necessarily lead to better results. The effort invested in idea generation, such as more extensive submission (“spamming”) and creative inspiration (“copying”), could be wasted and even has adverse effects on idea success. However, especially effort invested into idea championing provides strong possibilities to increase idea success
Local water management in cotton linter papers with silica-based coatings
No full textPaper with its mechanical strength as well as due to its microfluidic properties has emerged as an interesting sustainable material for future high-tech applications. Examples include paper-based sensors and actuators, paper-based construction materials and paper-based membranes. These examples have in common that a precise control of the water distribution inside the paper sheet during fluid water imbibition, water vapor adsorption, or drying affects the fluidic properties of the paper, which are crucial for its performance. Here silica-based coatings are applied to control the water distribution in the paper sheet during imbibition, adsorption and drying. By using dense silica coatings, the fibers are shielded from water penetration which limits the water distribution into the fiber–fiber voids. Whereas with a mesoporous silica coating, mesopores can be inserted into the paper, providing an additional space for water imbibition and adsorption. Water location upon imbibition, adsorption and drying were investigated using small angle x-ray scattering and gravimetric water vapor adsorption. Thereby, water distribution upon imbibition and adsorption depends on the type of silica coating. In addition, the drying mechanism and water distribution during drying is as well determined by the silica-based coating. The obtained results allow to deduce design criteria for local water management in paper sheets
DiffProb: Data Pruning for Face Recognition
No full textFace recognition models have made substantial progress due to advances in deep learning and the availability of large-scale datasets. However, reliance on massive annotated datasets introduces challenges related to training computational cost and data storage, as well as potential privacy concerns regarding managing large face datasets. This paper presents DiffProb, the first data pruning approach for the application of face recognition. DiffProb assesses the prediction probabilities of training samples within each identity and prunes the ones with identical or close prediction probability values, as they are likely reinforcing the same decision boundaries, and thus contribute minimally with new information. We further enhance this process with an auxiliary cleaning mechanism to eliminate mislabeled and label-flipped samples, boosting data quality with minimal loss. Extensive experiments on CASIA-WebFace with different pruning ratios and multiple benchmarks, including LFW, CFP-FP, and IJB-C, demonstrate that DiffProb can prune up to 50% of the dataset while maintaining or even, in some settings, improving the verification accuracies. Additionally, we demonstrate DiffProb’s robustness across different architectures and loss functions. Our method significantly reduces training cost and data volume, enabling efficient face recognition training and reducing the reliance on massive datasets and their demanding management. The code, pretrained models, and pruned datasets are publicly released: https://github.com/EduardaCaldeira/DiffProb