Joule heating as a smart approach in enhancing early strength development of mineral-impregnated carbon-fibre composites (MCF) made with geopolymer

The article at hand presents a novel approach to accelerating the early strength development of mineralimpregnated carbon-fibre composites (MCF) by electrical Joule heating. MCF were produced with a metakaolin-based geopolymer suspension and subsequently cured using Ohmic heating under systemically varied voltages and durations. The MCF produced were characterised in respect of their mechanical and morphological properties. Threepoint-bending and uniaxial tension tests yielded significant enhancement of MCF mechanical properties due to curing within only a few hours. Thermogravimetric analysis (TGA), mercury intrusion porosimetry (MIP), environmental scanning electron microscope (ESEM) as well as micro-computed tomography (μCT) confirmed advanced geopolymerisation by the electrical heating process and a strong sensitivity to parameter selection. After only two hours of resistance heating MCF could demonstrate tensile strength of up to 2800 MPa, showing the great potential for applying the Joule effect as a possibility to enhance the strength development of geopolymer-based MCF. Moreover, the applied method offers a huge potential to manufacture automated fast out-of-oven cured MCF with a variety of shapes and dimensions

Development and testing of fast curing, mineral-impregnated carbon fiber (MCF) reinforcements based on metakaolin-made geopolymers

Mineralisch getränkte Carbonfasern (MCF) stellen eine vielversprechende Alternative zu herkömmlichen Stahlbewehrung in Beton dar. Für eine effiziente industrielle Herstellung von MCF muss eine ausreichende Verarbeitungszeit für die Imprägniersuspension gewährleistet sein. In der vorliegenden Untersuchung wurde zu diesem Zweck ein aus Metakaolin hergestelltes Geopolymer (GP) entwickelt und getestet. Die Tränkung von Carbonfasergarnen wurde kontinuierlich und automatisiert durchgeführt. Anschließend wurden die MCF bei 75 °C wärmebehandelt, um die Reaktionsprozesse zu beschleunigen. Die mechanische Leistung von MCF nahm im Verlauf des Aushärtungsprozesses von 2 auf 8 Stunden allmählich zu, was auf das größere Ausmaß der Geopolymerisation zurückzuführen ist. Bei einer solchen verlängerten Aushärtung zeigten thermogravimetrische und mikroskopische Analysen zwar eine stärkere 'reagierte' Mikrostruktur, aber auch einen höheren Gehalt an Hohlräumen. Nach 8-stündigen Erhitzen erreichten die Zugfestigkeit und der Young-Modul von MCF 2960 MPa bzw. 259 GPa, bezogen auf die Garnquerschnittsfläche.:Abstract Schlagwörter 1. Einleitung 2. Experimentelles Programm 2.1. Materialien 2.2. Herstellung von MCF 2.3. Testen der Geopolymermatrix 2.4. Mechanische Prüfung von MCF 2.5. Morphologische Charakterisierung 3. Ergebnisse und Diskussion 3.1. Charakterisierung der Geopolymermatrix 3.2. Hergestellte MCF mit Geopolymer und Wärmebehandlung bei 75 °C. 3.3. Chemische und morphologische Analyse 4. Schlussfolgerung Erklärung des konkurrierenden Interesses LiteraturenMineral-impregnated, carbon fiber composites (MCF) are a promising alternative to conventional concrete reinforcements. For the efficient industrial production of MCF, sufficient processing time for the impregnation suspension must be ensured. In the present investigation, a metakaolin-made geopolymer (GP) has been developed and tested for this purpose. The impregnation of carbon-fiber yarns was performed continuously and automated. Subsequently, the MCF were heat-treated at 75 °C to accelerate the reaction processes. The mechanical performance of MCF gradually increased in the advancement of the curing process from 2 to 8 h, which is attributed to the greater extent of geopolymerization. In such extended curing, thermogravimetric and microscopic analysis showed indeed a more “reacted” microstructure but also a higher content of voids. After heating for 8 h, the tensile strength and Young's modulus of MCF reached 2960 MPa and 259 GPa, respectively, when related to the yarn cross-sectional area.:Abstract Schlagwörter 1. Einleitung 2. Experimentelles Programm 2.1. Materialien 2.2. Herstellung von MCF 2.3. Testen der Geopolymermatrix 2.4. Mechanische Prüfung von MCF 2.5. Morphologische Charakterisierung 3. Ergebnisse und Diskussion 3.1. Charakterisierung der Geopolymermatrix 3.2. Hergestellte MCF mit Geopolymer und Wärmebehandlung bei 75 °C. 3.3. Chemische und morphologische Analyse 4. Schlussfolgerung Erklärung des konkurrierenden Interesses Literature

Electrical Joule Heating and Early Strength of Mineral-impregnated Carbon Fibre Reinforcement (MCF)

Mineral-impregnated carbon fibre reinforcement (MCF) has attracted increasing attention due to its low-cost, easy manufacturing, high temperature and chloride resistance, when it replaces traditional steel reinforcement for concrete construction. Considering its excellent electrical conductivity, this paper investigates the effect of electrical Joule heating on the temperature increase, mechanical and microstructural characteristics of MCF. Different duration of electrical heating ranging from 0.5h, 1h, 2h, 4h to 8h had been explored. In addition, the effect of water spray treatment on the electrically heated MCF will be conducted. For the MCF reference without electrical heating, it is not hardened and the early flexural strength can’t be obtained. The temperature of MCF under the voltage of 15 V gradually increases to 100.5 °C and then keeps stable. The highest early flexural strength of MCF immediately tested after heating reached 290.8 MPa when the electrical heating time is 8h, and with the water spray treatment. Interestingly, the water spray treatment seems to benefit the strength development, with the less generated micro pores around the interfaces of carbon fibres to cement matrix. The results indicate that the rapid hardening MCF subjected to electrical heating can work as self-heating elements or rapid production and transportation of MCF for concrete structures

Data-Driven Decisions and Actions in Today’s Software Development

Today’s software development is all about data: data about the software product itself, about the process and its different stages, about the customers and markets, about the development, the testing, the integration, the deployment, or the runtime aspects in the cloud. We use static and dynamic data of various kinds and quantities to analyze market feedback, feature impact, code quality, architectural design alternatives, or effects of performance optimizations. Development environments are no longer limited to IDEs in a desktop application or the like but span the Internet using live programming environments such as Cloud9 or large-volume repositories such as BitBucket, GitHub, GitLab, or StackOverflow. Software development has become “live” in the cloud, be it the coding, the testing, or the experimentation with different product options on the Internet. The inherent complexity puts a further burden on developers, since they need to stay alert when constantly switching between tasks in different phases. Research has been analyzing the development process, its data and stakeholders, for decades and is working on various tools that can help developers in their daily tasks to improve the quality of their work and their productivity. In this chapter, we critically reflect on the challenges faced by developers in a typical release cycle, identify inherent problems of the individual phases, and present the current state of the research that can help overcome these issues

Durable Textile-reinforced Concrete Made of Fast-setting, Mineralimpregnated Carbon-fibers (MCF) Reinforcements and Alkaline-activated Matrix

Textile Reinforced Concrete (TRC) is a class of material with massive potential to strengthen existing or build entirely new thin-walled structures. However, state-of-the-art polymer-based textile reinforcements commonly suffer under weak compatibility with concrete and insufficient reinforcing efficiency at elevated temperatures. Mineral-impregnated carbon-fiber (MCF) composites represent instead a promising alternative reinforcement with a wide-ranging innovation potential regarding digital and automated processability, freedom design, chemical compatibility and ecological and environmental footprints. Among the existing variants of mineral impregnation, geopolymer (GP) impregnation for carbon fiber (CF) enables stable early-age rheological properties and fast-setting by moderate-temperature activation. The paper at hand presents a methodology to automatically manufacture textile reinforcements made of MCF composites via a continuous pultrusion and robotic–assisted structuring process to meet future market demands. After an advanced geopolymerisation process by thermal curing, the resulting gridlike reinforcements were implemented in a fine-grained, alkali-activated material (AAM) based concrete matrix and characterized with respect to their uniaxial tensile performance. By further applying AAM as cement-free binder, sustainable and fireproof reinforced concrete can be designed with an evident reduction in CO2 emission as compared to conventional cementitious systems. The improved chemical affinity facilitated by GP impregnation governs the cracking phase, resulting in a finer and more diffuse pattern, whereas the higher unidirectional strength of epoxy (EP)-impregnated yarns is responsible for the higher ultimate strength of the composite

Context-dependent neocentromere activity in synthetic yeast chromosome VIII

Pioneering advances in genome engineering, and specifically in genome writing, have revolutionized the field of synthetic biology, propelling us toward the creation of synthetic genomes. The Sc2.0 project aims to build the first fully synthetic eukaryotic organism by assembling the genome of Saccharomyces cerevisiae. With the completion of synthetic chromosome VIII (synVIII) described here, this goal is within reach. In addition to writing the yeast genome, we sought to manipulate an essential functional element: the point centromere. By relocating the native centromere sequence to various positions along chromosome VIII, we discovered that the minimal 118-bp CEN8 sequence is insufficient for conferring chromosomal stability at ectopic locations. Expanding the transplanted sequence to include a small segment (~500 bp) of the CDEIII-proximal pericentromere improved chromosome stability, demonstrating that minimal centromeres display context-dependent functionality </p

Synthetic chromosome fusion: Effects on mitotic and meiotic genome structure and function

We designed and synthesized synI, which is ~21.6% shorter than native chrI, the smallest chromosome in Saccharomyces cerevisiae. SynI was designed for attachment to another synthetic chromosome due to concerns surrounding potential instability and karyotype imbalance and is now attached to synIII, yielding the first synthetic yeast fusion chromosome. Additional fusion chromosomes were constructed to study nuclear function. ChrIII-I and chrIX-III-I fusion chromosomes have twisted structures, which depend on silencing protein Sir3. As a smaller chromosome, chrI also faces special challenges in assuring meiotic crossovers required for efficient homolog disjunction. Centromere deletions into fusion chromosomes revealed opposing effects of core centromeres and pericentromeres in modulating deposition of the crossover-promoting protein Red1. These effects extend over 100 kb and promote disproportionate Red1 enrichment, and thus crossover potential, on small chromosomes like chrI. These findings reveal the power of synthetic genomics to uncover new biology and deconvolute complex biological systems  </p

Debugging and consolidating multiple synthetic chromosomes reveals combinatorial genetic interactions

The Sc2.0 project is building a eukaryotic synthetic genome from scratch. A major milestone has been achieved with all individual Sc2.0 chromosomes assembled. Here, we describe the consolidation of multiple synthetic chromosomes using advanced endoreduplication intercrossing with tRNA expression cassettes to generate a strain with 6.5 synthetic chromosomes. The 3D chromosome organization and transcript isoform profiles were evaluated using Hi-C and long-read direct RNA sequencing. We developed CRISPR Directed Biallelic URA3-assisted Genome Scan, or ‘‘CRISPR D-BUGS,’’ to map phenotypic variants caused by specific designer modifications, known as ‘‘bugs.’’ We first fine-mapped a bug in synthetic chromosome II (synII) and then discovered a combinatorial interaction associated with synIII and synX, revealing an unexpected genetic interaction that links transcriptional regulation, inositol metabolism, and tRNASer CGA abundance. Finally, to expedite consolidation, we employed chromosome substitution to incorporate the largest chromosome (synIV), thereby consolidating &gt;50% of the Sc2.0 genome in one strain </p

Manipulating the 3D organization of the largest synthetic yeast chromosome

Whether synthetic genomes can power life has attracted broad interest in the synthetic biology field. Here, we report de novo synthesis of the largest eukaryotic chromosome thus far, synIV, a 1,454,621-bp yeast chromosome resulting from extensive genome streamlining and modification. We developed megachunk assembly combined with a hierarchical integration strategy, which significantly increased the accuracy and flexibility of synthetic chromosome construction. Besides the drastic sequence changes, we further manipulated the 3D structure of synIV to explore spatial gene regulation. Surprisingly, we found few gene expression changes, suggesting that positioning inside the yeast nucleoplasm plays a minor role in gene regulation. Lastly, we tethered synIV to the inner nuclear membrane via its hundreds of loxPsym sites and observed transcriptional repression of the entire chromosome, demonstrating chromosome-wide transcription manipulation without changing the DNA sequences. Our manipulation of the spatial structure of synIV sheds light on higher-order architectural design of the synthetic genomes. </p

Synthetic yeast chromosome XI design provides a testbed for the study of extrachromosomal circular DNA dynamics

We describe construction of the synthetic yeast chromosome XI (synXI) and reveal the effects of redesign at non-coding DNA elements. The 660-kb synthetic yeast genome project (Sc2.0) chromosome was assembled from synthesized DNA fragments before CRISPR-based methods were used in a process of bug discovery, redesign, and chromosome repair, including precise compaction of 200 kb of repeat sequence. Repaired defects were related to poor centromere function and mitochondrial health and were associated with modifications to non-coding regions. As part of the Sc2.0 design, loxPsym sequences for Cre-mediated recombination are inserted between most genes. Using the GAP1 locus from chromosome XI, we show that these sites can facilitate induced extrachromosomal circular DNA (eccDNA) formation, allowing direct study of the effects and propagation of these important molecules. Construction and characterization of synXI contributes to our understanding of non-coding DNA elements, provides a useful tool for eccDNA study, and will inform future synthetic genome design