Digital Light Processing 3D printing of Thermosets via Reversible Addition-Fragmentation Chain Transfer Polymerization

Digital light processing (DLP) 3D printing is an efficient additive manufacturing technique for the fabrication of 3D objects with intricate structures. However, current photocurable resins for DLP printing are mainly based on uncontrolled radical polymerizations associated with limited control over formed networks and a high degree of heterogeneity in macromolecular structures. This uncontrolled process could only afford narrow manipulation over bulk material properties, restricting the wide applications of DLP 3D-printed materials. To access versatile control over bulk material properties, reversible-deactivation radical polymerization (RDRP) has been widely applied to tune the macromolecular structures of polymer networks. In particular, photo-mediated reversible addition-fragmentation chain transfer (photoRAFT) polymerization has been employed to design photocurable resins for DLP printing of materials with homogeneous networks and enhanced properties. To deepen the understanding of using photoRAFT polymerization in designing photocurable resins for DLP 3D printing processes, this body of work first investigated the role of RAFT agent architectures (i.e., different number of arms) in a visible-light-mediated photoinduced electron/energy transfer (PET)-RAFT system. The monofunctional RAFT agent resulted in optimal mechanical properties among the studied candidates. Subsequently, the optimized monofunctional RAFT agent was employed in silica nanoparticle-loaded composite photocurable resins based on type I-initiated RAFT polymerization, which produced composite materials with more homogeneous networks and improved tensile properties. As an extension of small molecule RAFT agents, macro-chain transfer agents (macroCTAs) were subsequently utilized to design photocurable resins for printing nanostructured materials via polymerization-induced microphase separation (PIMS). Similarly, macroCTA with 1, 2, and 4-arm were used to study the architecture effect in the PIMS process. The results demonstrated that the nanostructural domain sizes were precisely defined by the arm length of macroCTAs, while the 2 and 4-arm macroCTAs led to phase-inverted morphologies which were not observed in the case of using 1-arm macroCTAs. Afterward, diblock macroCTAs with varied compositions and sequences were employed in the PIMS printing system. Tuning ratio of network-incompatible A and B blocks in macroCTA enables a transition from bicontinuous to less connected morphologies. More importantly, the macroCTA block sequence was also found to significantly affect the PIMS process, nanostructure, and bulk properties of 3D printed materials

An Efficient Resilient MPC Scheme via Constraint Tightening against Cyberattacks: Application to Vehicle Cruise Control

We propose a novel framework for designing a resilient Model Predictive Control (MPC) targeting uncertain linear systems under cyber attack. Assuming a periodic attack scenario, we model the system under Denial of Service (DoS) attack, also with measurement noise, as an uncertain linear system with parametric and additive uncertainty. To detect anomalies, we employ a Kalman filter-based approach. Then, through our observations of the intensity of the launched attack, we determine a range of possible values for the system matrices, as well as establish bounds of the additive uncertainty for the equivalent uncertain system. Leveraging a recent constraint tightening robust MPC method, we present an optimization-based resilient algorithm. Accordingly, we compute the uncertainty bounds and corresponding constraints offline for various attack magnitudes. Then, this data can be used efficiently in the MPC computations online. We demonstrate the effectiveness of the developed framework on the Adaptive Cruise Control (ACC) problem.Comment: To Appear in ICINCO 202

MiLMo:Minority Multilingual Pre-trained Language Model

Pre-trained language models are trained on large-scale unsupervised data, and they can fine-turn the model only on small-scale labeled datasets, and achieve good results. Multilingual pre-trained language models can be trained on multiple languages, and the model can understand multiple languages at the same time. At present, the search on pre-trained models mainly focuses on rich resources, while there is relatively little research on low-resource languages such as minority languages, and the public multilingual pre-trained language model can not work well for minority languages. Therefore, this paper constructs a multilingual pre-trained model named MiLMo that performs better on minority language tasks, including Mongolian, Tibetan, Uyghur, Kazakh and Korean. To solve the problem of scarcity of datasets on minority languages and verify the effectiveness of the MiLMo model, this paper constructs a minority multilingual text classification dataset named MiTC, and trains a word2vec model for each language. By comparing the word2vec model and the pre-trained model in the text classification task, this paper provides an optimal scheme for the downstream task research of minority languages. The final experimental results show that the performance of the pre-trained model is better than that of the word2vec model, and it has achieved the best results in minority multilingual text classification. The multilingual pre-trained model MiLMo, multilingual word2vec model and multilingual text classification dataset MiTC are published on http://milmo.cmli-nlp.com/

catena-Poly[[aqua­(3-methyl­benzoato-κ2 O,O′)lead(II)]-μ-3-methyl­benzoato-κ4 O:O,O′:O′]

The reaction of lead(II) acetate and 3-methyl­benzoic acid (MBA) in aqueous solution yielded the title polymer, [Pb(C8H7O2)2(H2O)]n. The asymmetric unit contains two PbII atoms, four MBA ligands and two water mol­ecules. Each PbII cation is hepta­coordinated and chelated by four carboxyl­ate O atoms from two MBA ligands. The Pb atoms are bridged through the carboxyl­ate O atoms from another two MBA ligands, leading to a central Pb2O2 core. The Pb—O bond lengths are in the range 2.325 (3)–2.757 (4) Å. The intra- and inter­dimer Pb⋯Pb distances are 4.2942 (3) and 4.2283 (3) Å, respectively, indicating little direct metal–metal inter­action. The coordinating water mol­ecules and carboxyl­ate O atoms are involved in extensive O—H⋯O hydrogen-bonding inter­actions. The complex has an extended ladder-like chain structure and the chains are assembled by hydrogen bonds and π–π inter­actions [centroid–centroid distance = 3.6246 (3) Å] into a three-dimensional supra­molecular structure

Nanofibrous Spongy Microspheres for the Delivery of Hypoxia-primed Human Dental Pulp Stem Cells to Regenerate Vascularized Dental Pulp

Dental pulp infection and necrosis are widespread diseases. Conventional endodontic treatments result in a devitalized and weakened tooth. In this work, we synthesized novel star-shaped polymer to self-assemble into unique nanofibrous spongy microspheres (NF-SMS), which were used to carry human dental pulp stem cells (hDPSCs) into the pulp cavity to regenerate living dental pulp tissues. It was found that NF-SMS significantly enhanced hDPSCs attachment, proliferation, odontogenic differentiation and angiogenesis, as compared to control cell carriers. Additionally, NF-SMS promoted vascular endothelial growth factor (VEGF) expression of hDPSCs in a 3D hypoxic culture. Hypoxia-primed hDPSCs/NF-SMS complexes were injected into the cleaned pulp cavities of rabbit molars for subcutaneous implantation in mice. After 4 weeks, the hypoxia group significantly enhanced angiogenesis inside the pulp chamber and promoted the formation of ondontoblast-like cells lining along the dentin-pulp interface, as compared to the control groups (hDPSCs alone group, NF-SMS alone group, and hDPSCs/NF-SMS group pre-cultured under normoxic conditions). Furthermore, in an in situ dental pulp repair model in rats, hypoxia-primed hDPSCs/NF-SMS were injected to fully fill the pulp cavity and regenerate pulp-like tissues with a rich vasculature and a histological structure similar to the native pulp

Field investigation on the impact of vehicle traffic on the vibration of ancient seawalls in Qiantang River

To investigate the vibrational impact of vehicular traffic on the ancient Qiantang River seawall, on-site measurements of the seawall’s pulsation and forced vibrations under different vehicle speeds and axle loads were conducted. The acquired data were analyzed in the time domain, frequency domain, and 1/3 octave bands, revealing the time-frequency vibrational characteristics of the ancient seawall structure. The results indicate that the characteristic frequencies of the ancient seawall are 3 Hz and 10 Hz, with the primary frequency band of the structural vibrations induced by vehicular traffic ranging from 0 to 30 Hz. Vehicle traffic primarily caused vertical vibrations in the seawall structure, with along-dike horizontal vibrations being significantly higher than cross-dike vibrations. Based on the measurement results, an empirical relationship between the peak vibration velocity of the ancient seawall and variations in vehicle speed and axle load was established. It was found that, compared to axle load, increased vehicle speed had a more pronounced amplification effect on the structural vibrations of the ancient seawall. To ensure the vibrational safety of the ancient seawall relics, maximum vehicle speeds for different loading conditions of tri-axle trucks were provided based on vibration limits: for an axle load of 10 t, speeds should be below 34 km/h; for 11.52 t, below 24 km/h; for 13.04 t, below 20 km/h; and for 14.56 t, below 15 km/h

Experimental performance analysis of a dual source heat pump integrated with thermal energy storage

To mitigate disturbances to the electric grid resulting from the growing penetration of intermittent and decentralized renewable generation, a dual-source (air source and ground source) heat pump (DSHP) integrated with thermal energy storage (TES) was developed. The DSHP can use either ambient air or the shallow subsurface of the ground to provide space heating or space cooling to the building as the conventional heat pump and produce hot/cold water for charging TES. Using dual sources (air and ground) can reduce the required size of the expensive ground heat exchangers while retaining high energy efficiency. During the off-peak period, the DSHP cools/heats the TES with low-cost electricity or overproduced renewable power. The stored cooling/heating energy in the TES is released during peak hours of the electric grid to meet the thermal demands of the building without consuming electricity to run the DSHP. A 2-ton (7 kW) prototype DSHP was developed and integrated with a 50-gallon (189 L) TES tank filled with a phase change material. Field tests were conducted to characterize the performance of the integrated system operating in various operation modes

Methylation by Set9 Modulates FoxO3 Stability and Transcriptional Activity

The FoxO family of transcription factors plays an important role in longevity and tumor suppression by regulating the expression of a wide range of target genes. FoxO3 has recently been found to be associated with extreme longevity in humans and to regulate the homeostasis of adult stem cell pools in mammals, which may contribute to longevity. The activity of FoxO3 is controlled by a variety of post-translational modifications that have been proposed to form a ‘code’ affecting FoxO3 subcellular localization, DNA binding ability, protein-protein interactions and protein stability. Lysine methylation is a crucial post-translational modification on histones that regulates chromatin accessibility and is a key part of the ‘histone code’. However, whether lysine methylation plays a role in modulating FoxO3 activity has never been examined. Here we show that the methyltransferase Set9 directly methylates FoxO3 in vitro and in cells. Using a combination of tandem mass spectrometry and methyl-specific antibodies, we find that Set9 methylates FoxO3 at a single residue, lysine 271, a site previously known to be deacetylated by Sirt1. Methylation of FoxO3 by Set9 decreases FoxO3 protein stability, while moderately increasing FoxO3 transcriptional activity. The modulation of FoxO3 stability and activity by methylation may be critical for fine-tuning cellular responses to stress stimuli, which may in turn affect FoxO3's ability to promote tumor suppression and longevity