Recycling of carbon fibre via pyrolysis technologies

Carbon fibre reinforced plastic (CFRP) composites have been widely used in many industrial fields, such as the automotive and aviation industries, due to their impressive properties including being lightweight, corrosion-resistant and having a high strength to weight ratio. This inevitably generates large amounts of composites waste during the manufacturing process and when these composite products reach the end of their service life. Considering the environmental and economic impact, composites recycling has become one of the top priorities for composite industries. Currently the main recycling techniques that have been developed include mechanical recycling, chemical solvolysis and pyrolysis. Among all these, pyrolysis has been proven to be the most promising recycling technique. This study focuses on pyrolysis techniques, further optimizes and develops pyrolysis methods including conventional pyrolysis, hybrid pyrolysis method and microwave pyrolysis from the aspect of char elimination, so that a higher quality carbon fibre can be recovered with a potential for energy saving. At the beginning of the study, an optimization of conventional pyrolysis was conducted to reduce the char formation via the thermal analysis of two types carbon fibre thermoset composite. The effect of pyrolytic conditions, in terms of heating rate, pyrolysis temperature and inert gas flow rate on char retention and intrinsic reactivity were investigated. It was found the pyrolytic char formation reduced as the heating rate, pyrolysis temperature, and gas flow rate increased, whilst the char intrinsic reactivity increased with fast heating rate and low temperature. The improvement in intrinsic reactivities were attributed to the rise in oxygen-to-carbon ratio, char pore size, and BET surface area. A more porous structure was observed from the char generated from a fast heating rate and high temperature. This consolidated the effect of pyrolytic conditions on the char intrinsic reactivity. This research confirmed that the appropriate selection of pyrolytic reaction conditions not only reduces the char yield, but also improves the char oxidation activity. Secondly, a new hybrid recycling approach was developed to reduce char formation significantly using a combination of a chemical pre-treatment followed by a conventional pyrolysis process. Zinc chloride/ethanol solution was selected as the pre-treatment agent. After immersing carbon fibre epoxy prepreg in the 40 wt.% ZnCI2/C2H5OH solution at 80 °C for 2 hours, some tiny cracks appeared on the surface of the prepreg and the required pyrolysis temperature reduced. The surface morphology and chemistry, mechanical performance of recycled carbon fibre have been investigated. The recycled carbon fibres retained a competitive mechanical performance closed to virgin carbon fibre and appeared to have a relatively clean surface with small residues. As compared with the standard pyrolysis recycling process, this hybrid method results in carbon fibre with higher mechanical performance. Finally, the utilisation of microwave pyrolysis was attempted in a multi-mode microwave reactor to potentially improve the pyrolysis efficiency. The pyrolytic products distributions and properties of carbon fibre epoxy prepreg pyrolyzed at different microwave temperatures of 450 °C, 550 °C and 650 °C were investigated. It was found that higher temperatures resulted in less char formation and a higher yield of gas and liquid products. The carbon fibre recovered at 450 °C showed the highest tensile strength, while there was no significant change in tensile modulus for carbon fibre extracted at different microwave temperatures. The recycled carbon fibre showed a relatively clean surface, with increasing number of oxygen-containing groups. The gas released from the process has a composition of H2, CO and CO2, and the major liquid product components are phenols and aromatics. The microwave pyrolysis has demonstrated a potential as a low energy consuming method of carbon fibre pyrolysis recycling. In summary, carbon fibre was successfully recycled from a carbon fibre composite using various pyrolysis technologies in this research. The optimization and development of these pyrolysis technologies have the potential not only to reduce or eliminate the char formation, but also to recover high-quality fibre and save thermal energy

Bkd-FedGNN: A Benchmark for Classification Backdoor Attacks on Federated Graph Neural Network

Federated Graph Neural Network (FedGNN) has recently emerged as a rapidly growing research topic, as it integrates the strengths of graph neural networks and federated learning to enable advanced machine learning applications without direct access to sensitive data. Despite its advantages, the distributed nature of FedGNN introduces additional vulnerabilities, particularly backdoor attacks stemming from malicious participants. Although graph backdoor attacks have been explored, the compounded complexity introduced by the combination of GNNs and federated learning has hindered a comprehensive understanding of these attacks, as existing research lacks extensive benchmark coverage and in-depth analysis of critical factors. To address these limitations, we propose Bkd-FedGNN, a benchmark for backdoor attacks on FedGNN. Specifically, Bkd-FedGNN decomposes the graph backdoor attack into trigger generation and injection steps, and extending the attack to the node-level federated setting, resulting in a unified framework that covers both node-level and graph-level classification tasks. Moreover, we thoroughly investigate the impact of multiple critical factors in backdoor attacks on FedGNN. These factors are categorized into global-level and local-level factors, including data distribution, the number of malicious attackers, attack time, overlapping rate, trigger size, trigger type, trigger position, and poisoning rate. Finally, we conduct comprehensive evaluations on 13 benchmark datasets and 13 critical factors, comprising 1,725 experimental configurations for node-level and graph-level tasks from six domains. These experiments encompass over 8,000 individual tests, allowing us to provide a thorough evaluation and insightful observations that advance our understanding of backdoor attacks on FedGNN.The Bkd-FedGNN benchmark is publicly available at https://github.com/usail-hkust/BkdFedGCN

Transfer Reinforcement Learning Based Negotiating Agent Framework

While achieving tremendous success, there is still a major issue standing out in the domain of automated negotiation: it is inefficient for a negotiating agent to learn a strategy from scratch when being faced with an unknown opponent. Transfer learning can alleviate this problem by utilizing the knowledge of previously learned policies to accelerate the current task learning. This work presents a novel Transfer Learning based Negotiating Agent (TLNAgent) framework that allows a negotiating agent to transfer previous knowledge from source strategies optimized by deep reinforcement learning, to boost its performance in new tasks. TLNAgent comprises three key components: the negotiation module, the adaptation module and the transfer module. To be specific, the negotiation module is responsible for interacting with the other agent during negotiation. The adaptation module measures the helpfulness of each source policy based on a fusion of two selection mechanisms. The transfer module is based on lateral connections between source and target networks and accelerates the agent’s training by transferring knowledge from the selected source strategy. Our comprehensive experiments clearly demonstrate that TL is effective in the context of automated negotiation, and TLNAgent outperforms state-of-the-art Automated Negotiating Agents Competition (ANAC) negotiating agents in various domains

MFAP3L activation promotes colorectal cancer cell invasion and metastasis

AbstractAn abundance of microfibril-associated glycoprotein 3-like (MFAP3L) significantly correlates with distant metastasis in colorectal cancer (CRC), although the mechanism has yet to be explained. In this study, we observed that MFAP3L knock-down resulted in reduced CRC cell invasion and hepatic metastasis. We evaluated the cellular location and biochemical functions of MFAP3L and found that this protein was primarily localized in the nucleus of CRC cells and acted as a protein kinase. When EGFR translocated into the nucleus upon stimulation with EGF, MFAP3L was phosphorylated at Tyr287 within its SH2 motif, and the activated form of MFAP3L phosphorylated ERK2 at Thr185 and Tyr187. Moreover, the metastatic behavior of CRC cells in vitro and in vivo could be partially explained by activation of the nuclear ERK pathway through MFAP3L phosphorylation. Hence, we experimentally demonstrated for the first time that MFAP3L likely participates in the nuclear signaling of EGFR and ERK2 and acts as a novel nuclear kinase that impacts CRC metastasis

The Uyghur population and genetic susceptibility to type 2 diabetes: potential role for variants in CAPN10, APM1 and FUT6 genes

Genome-wide association studies have successfully identified over 70 loci associated with the risk of type 2 diabetes mellitus (T2DM) in multiple populations of European ancestry. However, the risk attributable to an individual variant is modest and does not yet provide convincing evidence for clinical utility. Association between these established genetic variants and T2DM in general populations is hitherto understudied in the isolated populations, such as the Uyghurs, resident in Hetian, far southern Xinjiang Uyghur Autonomous Region, China. In this case–control study, we genotyped 13 single-nucleotide polymorphisms (SNPs) at 10 genes associated with diabetes in 130 cases with T2DM and 135 healthy controls of Uyghur, a Chinese minority ethnic group. Three of the 13 SNPs demonstrated significant association with T2DM in the Uyghur population. There were significant differences between the T2DM patients and controls in the risk allele distributions of rs3792267 (CAPN10) (P = 0.002), rs1501299 (APM1) (P = 0.017), and rs3760776 (FUT6) (P = 0.031). Allelic carriers of rs3792267-A, rs1501299-T, and rs3760776-T had a 2.24-fold [OR (95% CI): 1.35–3.71], 0.59-fold [OR (95% CI): 0.39–0.91], 0.57-fold [OR (95% CI): 0.34–0.95] increased risk for T2DM respectively. We further confirmed that the cumulative risk allelic scores calculated from the 13 susceptibility loci for T2DM differed significantly between the T2DM patients and controls (P = 0.001), and the effect of obesity/overweight on T2DM was only observed in the subjects with a combined risk allelic score under a value of 17. This study observed that the SNPs rs3792267 in CAPN10, rs1501299 in APM1, and rs3760776 in FUT6 might serve as potential susceptible biomarkers for T2DM in Uyghurs. The cumulative risk allelic scores of multiple loci with modest individual effects are also significant risk factors in Uyghurs for T2DM, particularly among non-obese individuals. This is the first investigation having observed/found genetic variations on genetic loci functionally linked with glycosylation associated with the risk of T2DM in a Uyghur population. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine

Using electroencephalography to analyse drivers’ different cognitive workload characteristics based on on-road experiment

Driver’s cognitive workload has an important impact on driving safety. This paper carries out an on-road experiment to analyse the impact from three innovative aspects: significance analysis of electroencephalogram (EEG) under different cognitive workloads, distribution of EEG maps with different frequency signals and influence of different cognitive workloads on driving safety based on EEG. First, the EEG signals are processed and four frequencies of delta, theta, alpha and beta are obtained. Then, the time–frequency transform and power spectral density calculation are carried out by short-time Fourier to study the correlation of each frequency signal of different workload states, as well as the distribution pattern of the EEG topographic map. Finally, the time and space energy and phase changes in each cognitive task event are studied through event-related spectral perturbation and inter-trial coherence. Results show the difference between left and right brains, as well as the resource occupancy trends of the monitor, perception, visual and auditory channels in different driving conditions. Results also demonstrate that the increase in cognitive workloads will directly affect driving safety. Changes in cognitive workload have different effects on brain signals, and this paper can provide a theoretical basis for improving driving safety under different cognitive workloads. Mastering the EEG characteristics of signals can provide more targeted supervision and safety warnings for the driver

Recovery of carbon fibre from waste prepreg via microwave pyrolysis

Management of waste from carbon fibre composites has become a significant societal issue as the application of composite grows across many industries. In this study, carbon fibres (CF) were successfully recovered from cured carbon fibre/epoxy (CF/EP) prepreg under microwave pyrolysis at 450, 550 and 650◦ C followed by oxidation of any residual char. The recovered fibres were investigated for their tensile properties, surface morphologies and the elements/functional groups presented on the surface. The chemical compositions of gaseous and oil pyrolysis products were also analysed. The microwave pyrolysis effectively pyrolyzed the epoxy (EP) resin. Char residue remained on the fibre surface and the amount of char reduced as the pyrolysis temperature increased. Compared to virgin fibres, the recovered fibre suffered from a strength reduction by less than 20%, and this reduction could be mitigated by reducing the pyrolysis temperature. The surface of recovered fibre remained clean and smooth, while the profile of elements and functional groups at the surface were similar to those of virgin fibres. The main gaseous products were CO, H2, CO2 and CH4, whilst the liquid product stream included phenolic and aromatic compounds