Interface Effects on He Ion Irradiation in Nanostructured Materials

In advanced fission and fusion reactors, structural materials suffer from high dose irradiation by energetic particles and are subject to severe microstructure damage. He atoms, as a byproduct of the (n) transmutation reaction, could accumulate to form deleterious cavities, which accelerate radiation-induced embrittlement, swelling and surface deterioration, ultimately degrade the service lifetime of reactor materials. Extensive studies have been performed to explore the strategies that can mitigate He ion irradiation damage. Recently, nanostructured materials have received broad attention because they contain abundant interfaces that are efficient sinks for radiation-induced defects. In this review, we summarize and analyze the current understandings on interface effects on He ion irradiation in nanostructured materials. Some key challenges and research directions are highlighted for studying the interface effects on radiation damage in nanostructured materials

Efficient Test-Time Model Adaptation without Forgetting

Test-time adaptation (TTA) seeks to tackle potential distribution shifts between training and testing data by adapting a given model w.r.t. any testing sample. This task is particularly important for deep models when the test environment changes frequently. Although some recent attempts have been made to handle this task, we still face two practical challenges: 1) existing methods have to perform backward computation for each test sample, resulting in unbearable prediction cost to many applications; 2) while existing TTA solutions can significantly improve the test performance on out-of-distribution data, they often suffer from severe performance degradation on in-distribution data after TTA (known as catastrophic forgetting). In this paper, we point out that not all the test samples contribute equally to model adaptation, and high-entropy ones may lead to noisy gradients that could disrupt the model. Motivated by this, we propose an active sample selection criterion to identify reliable and non-redundant samples, on which the model is updated to minimize the entropy loss for test-time adaptation. Furthermore, to alleviate the forgetting issue, we introduce a Fisher regularizer to constrain important model parameters from drastic changes, where the Fisher importance is estimated from test samples with generated pseudo labels. Extensive experiments on CIFAR-10-C, ImageNet-C, and ImageNet-R verify the effectiveness of our proposed method.Comment: 15 pages, conferenc

Intelligent Multi-Modal Sensing-Communication Integration: Synesthesia of Machines

In the era of sixth-generation (6G) wireless communications, integrated sensing and communications (ISAC) is recognized as a promising solution to upgrade the physical system by endowing wireless communications with sensing capability. Existing ISAC is mainly oriented to static scenarios with radio-frequency (RF) sensors being the primary participants, thus lacking a comprehensive environment feature characterization and facing a severe performance bottleneck in dynamic environments. To date, extensive surveys on ISAC have been conducted but are limited to summarizing RF-based radar sensing. Currently, some research efforts have been devoted to exploring multi-modal sensing-communication integration but still lack a comprehensive review. Therefore, we generalize the concept of ISAC inspired by human synesthesia to establish a unified framework of intelligent multi-modal sensing-communication integration and provide a comprehensive review under such a framework in this paper. The so-termed Synesthesia of Machines (SoM) gives the clearest cognition of such intelligent integration and details its paradigm for the first time. We commence by justifying the necessity of the new paradigm. Subsequently, we offer a definition of SoM and zoom into the detailed paradigm, which is summarized as three operation modes. To facilitate SoM research, we overview the prerequisite of SoM research, i.e., mixed multi-modal (MMM) datasets. Then, we introduce the mapping relationships between multi-modal sensing and communications. Afterward, we cover the technological review on SoM-enhance-based and SoM-concert-based applications. To corroborate the superiority of SoM, we also present simulation results related to dual-function waveform and predictive beamforming design. Finally, we propose some potential directions to inspire future research efforts.Comment: This paper has been accepted by IEEE Communications Surveys & Tutorial

High-strong-ductile magnesium alloys by interactions of nanoscale quasi-long period stacking order unit with twin.

Magnesium alloys with high strength in combination of good ductility are especially desirable for applications in transportation, aerospace and bio-implants owing to their high stiffness, abundant raw materials, and environmental friendliness. However, the majority of traditional strengthening approaches including grain refining and precipitate strengthening can usually prohibit dislocation movement at the expense of ductility invariably. Herein, we report an effective strategy for simultaneously enhancing yield strength (205 MPa, 2.41 times) and elongation (23%, 1.54 times) in a Mg-0.2Zn-0.6Y (at.%) alloy at room temperature, based on the formation of a nanosized quasi-long period stacking order unit (QLPSO)-twin structure by ultrahigh-pressure treatment followed by annealing. The formation reason and strong-ductile mechanism of the unique QLPSO-twin structure have been clarified by transmission electron microscopy observations and molecule dynamics simulations. The improved strength is mainly associated with the presence of nanosized QLPSO and the modified <86.3o QLPSO-twin boundary (TB) interface, effectively pinning dislocation movement. Comparatively, the enhanced ductility is related to the <3.7o QLPSO-TB interface and micro-kinks of nanoscale QLPSO, providing some paths for plastic deformation. This strategy on the QLPSO-twin structure might provide an alternative perspective for designing innovative hexagonal close-packed structural materials with superior mechanical properties

Performance enhancement of the soft robotic segment for a trunk-like arm

Introduction: Trunk-like continuum robots have wide applications in manipulation and locomotion. In particular, trunk-like soft arms exhibit high dexterity and adaptability very similar to the creatures of the natural world. However, owing to the continuum and soft bodies, their performance in payload and spatial movements is limited.Methods: In this paper, we investigate the influence of key design parameters on robotic performance. It is verified that a larger workspace, lateral stiffness, payload, and bending moment could be achieved with adjustments to soft materials’ hardness, the height of module segments, and arrayed radius of actuators.Results: Especially, a 55% increase in arrayed radius would enhance the lateral stiffness by 25% and a bending moment by 55%. An 80% increase in segment height would enlarge 112% of the elongation range and 70 % of the bending range. Around 200% and 150% increments in the segment’s lateral stiffness and payload forces, respectively, could be obtained by tuning the hardness of soft materials. These relations enable the design customization of trunk-like soft arms, in which this tapering structure ensures stability via the stocky base for an impact reduction of 50% compared to that of the tip and ensures dexterity of the long tip for a relatively larger bending range of over 400% compared to that of the base.Discussion: The complete methodology of the design concept, analytical models, simulation, and experiments is developed to offer comprehensive guidelines for trunk-like soft robotic design and enable high performance in robotic manipulation

Additives synergy for stable interface formation on rechargeable lithium metal anodes

Abstract(#br)The attention towards lithium (Li) metal anodes has been rekindled in recent years as it would boost the energy-density of Li batteries. However, notorious safety issues and cycling instability severely hinder their commercialization, especially when cycled in traditional carbonic ester electrolytes that exhibit a wide voltage window and are compatible with most of the cathode materials. Herein, lithium difluorophosphate (LiDFP) and vinylene carbonate (VC) are combined, and demonstrated to be synergistic in constructing in situ a mechanically stable and highly Li-ion conducting surface film on the Li metal anode. This results in uniform and compact Li deposition largely suppressing the formation of Li dendrites, dead lithium and irreversible Li-species as revealed by operando neutron depth profiling (NDP). This enables long-term cycling stability and enhancement of the Coulombic efficiency for rechargeable Li metal anodes. By combining solid state nuclear magnetic resonance (SSNMR) and spectroscopic studies, it is demonstrated that VC slows down the LiDFP reduction, yet promoting the breaking of the P–F bonds, which leads to a protective film. This film is rich in LiF–Li 3 PO 4 inorganic compounds, distributed homogeneously, that is embedded in a matrix of P–O–C species and macromolecular organic compounds like lithium ethylene dicarbonate. This composition is responsible for the improved ionic conductivity and mechanical stability of the protective film during extended cycles. The detailed insight in the additives interaction provides new opportunities for the design of rational surface films necessary for realizing high-performance lithium metal batteries

Radiomic analysis reveals DCE-MRI features for prediction of molecular subtypes of breast cancer

This work was supported in part by financial support from the National Natural Science Foundation of China (61271063 and 61401131), the National Basic Research Program of China (973 Program) (2013CB329502), and the Natural Science Foundation of Zhejiang Province of China (LZ15F010001 and LQ14F010011).The purpose of this study was to investigate the role of features derived from breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and to incorporated clinical information to predict the molecular subtypes of breast cancer. In particular, 60 breast cancers with the following four molecular subtypes were analyzed: luminal A, luminal B, human epidermal growth factor receptor-2 (HER2)-over-expressing and basal-like. The breast region was segmented and the suspicious tumor was depicted on sequentially scanned MR images from each case. In total, 90 features were obtained, including 88 imaging features related to morphology and texture as well as dynamic features from tumor and background parenchymal enhancement (BPE) and 2 clinical information-based parameters, namely, age and menopausal status. An evolutionary algorithm was used to select an optimal subset of features for classification. Using these features, we trained a multi-class logistic regression classifier that calculated the area under the receiver operating characteristic curve (AUC). The results of a prediction model using 24 selected features showed high overall classification performance, with an AUC value of 0.869. The predictive model discriminated among the luminal A, luminal B, HER2 and basal-like subtypes, with AUC values of 0.867, 0.786, 0.888 and 0.923, respectively. An additional independent dataset with 36 patients was utilized to validate the results. A similar classification analysis of the validation dataset showed an AUC of 0.872 using 15 image features, 10 of which were identical to those from the first cohort. We identified clinical information and 3D imaging features from DCE-MRI as candidate biomarkers for discriminating among four molecular subtypes of breast cancer.Yeshttp://www.plosone.org/static/editorial#pee

Enhancing ductility of ultrahigh strength metal-ceramic nanolayered composites

In recent years, two-phase nanolayered composites (also referred to as nanolaminated or nanoscale multilayers) with individual layer thicknesses varying from 200––300 nm down to 1–2 nm have been the subject of intensive study because of their unusual physical, chemical, and mechanical properties. For instance, with decreasing layer thicknesses (down to nanometer length scales), the mechanical response of these nanocomposites becomes increasingly interface dominated, and they exhibit ultrahigh strengths approaching the theoretical limit for ideal crystals. Moreover, if the constituent phases present large differences in strength, elastic modulus, and ductility, these multilayers give rise to new possibilities for the deformation mechanisms and properties of the composite as a whole. In this study we explore the possibility of synthesizing multilayered composites where one constituent phase has a low ductility, with a final goal of enhancing both the strength and ductility of the system. Using physical vapor deposition (PVD) techniques we synthesized two multilayered systems: a metal–ceramic Cu–TiN nanocomposite (where the ceramic is the brittle phase) and a hitherto unstudied hexagonal close-packed (HCP) – body-centered cubic (BCC) Mg–Nb system (where twinning in Mg leads to its lack of ductility), over a range of layer thicknesses ranging from 5 nm to 200 nm. Testing of such miniaturized systems poses significant challenges. We demonstrate the utility of both nanoindentation and compression testing of micropillars containing these multilayered nanocomposites to evaluate their deformation mechanisms. We utilize a novel lithographic polymer photomasking technique during the PVD synthesis of these multilayers to enable faster fabrication of the micropillars using focused ion beam technique. Micropillars were fabricated for three different orientations, with the interfaces oriented normal, parallel, and oblique (45°) to the compression axis, to explore the anisotropy in the mechanical response of the multilayer system. In the metal–ceramic system compression tests normal and parallel to the interface allow a complete understanding of the co-deformation response of the ceramic with its metallic counterpart, which is critical to the ductility of the system. The tests with the interfaces loaded obliquely provide a unique measure of interfacial shear strength. For the HCP–BCC system, these three orientations allow a detailed exploration of the propensity for twin formations in Mg as a function of their interface orientation. These results are compared for varying layer thicknesses and the results analyzed using the concepts of dislocation motion and interactions within the confined nanoscale layers