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"An, Yang"
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Evolution of tribo-induced interfacial nanostructures governing superlubricity in a-C:H and a-C:H:Si films
Hydrogenated amorphous carbon (a-C:H) is capable of providing a near-frictionless lubrication state when rubbed in dry sliding contacts. Nevertheless, the mechanisms governing superlubricity in a-C:H are still not well comprehended, mainly due to the lack of spatially resolved structural information of the buried contact surface. Here, we present structural analysis of the carbonaceous sliding interfaces at the atomic scale in two superlubricious solid lubricants, a-C:H and Si-doped a-C:H (a-C:H:Si), by probing the contact area using state-of-the-art scanning electron transmission microscopy and electron energy-loss spectroscopy. The results emphasize the diversity of superlubricity mechanisms in a-C:Hs. They suggest that the occurrence of a superlubricious state is generally dependent on the formation of interfacial nanostructures, mainly a tribolayer, by different carbon rehybridization pathways. The evolution of such anti-friction nanostructures highly depends on the contact mechanics and the counterpart material. These findings enable a more effective manipulation of superlubricity and developments of new carbon lubricants with robust lubrication properties.
Hydrogenated amorphous carbon is a promising solid lubricant, but the underlying mechanisms surrounding its superlubricity remain unclear. Here the authors reveal that the attainment of a superlubricious state is dependent on the
in-situ
in-situ formation of a nanostructured tribolayer through different carbon rehybridization pathways.
Journal Article
Sulfur Homeostasis in Plants
Sulfur (S) is an essential macronutrient for plant growth and development. S is majorly absorbed as sulfate from soil, and is then translocated to plastids in leaves, where it is assimilated into organic products. Cysteine (Cys) is the first organic product generated from S, and it is used as a precursor to synthesize many S-containing metabolites with important biological functions, such as glutathione (GSH) and methionine (Met). The reduction of sulfate takes place in a two-step reaction involving a variety of enzymes. Sulfate transporters (SULTRs) are responsible for the absorption of SO42− from the soil and the transport of SO42− in plants. There are 12–16 members in the S transporter family, which is divided into five categories based on coding sequence homology and biochemical functions. When exposed to S deficiency, plants will alter a series of morphological and physiological processes. Adaptive strategies, including cis-acting elements, transcription factors, non-coding microRNAs, and phytohormones, have evolved in plants to respond to S deficiency. In addition, there is crosstalk between S and other nutrients in plants. In this review, we summarize the recent progress in understanding the mechanisms underlying S homeostasis in plants.
Journal Article
Three-Stage Wiener-Process-Based Model for Remaining Useful Life Prediction of a Cutting Tool in High-Speed Milling
Tool condition monitoring can be employed to ensure safe and full utilization of the cutting tool. Hence, remaining useful life (RUL) prediction of a cutting tool is an important issue for an effective high-speed milling process-monitoring system. However, it is difficult to establish a mechanism model for the life decreasing process owing to the different wear rates in various stages of cutting tool. This study proposes a three-stage Wiener-process-based degradation model for the cutting tool wear estimation and remaining useful life prediction. Tool wear stages classification and RUL prediction are jointly addressed in this work in order to take full advantage of Wiener process, as this three-stage Wiener process definitely constitutes to describe the degradation processes at different wear stages, based on which the overall useful life can be accurately obtained. The numerical results obtained using extensive experiment indicate that the proposed model can effectively predict the cutting tool’s remaining useful life. Empirical comparisons show that the proposed model performs better than existing models in predicting the cutting tool RUL.
Journal Article
Auto-Denoising for EEG Signals Using Generative Adversarial Network
The brain–computer interface (BCI) has many applications in various fields. In EEG-based research, an essential step is signal denoising. In this paper, a generative adversarial network (GAN)-based denoising method is proposed to denoise the multichannel EEG signal automatically. A new loss function is defined to ensure that the filtered signal can retain as much effective original information and energy as possible. This model can imitate and integrate artificial denoising methods, which reduces processing time; hence it can be used for a large amount of data processing. Compared to other neural network denoising models, the proposed model has one more discriminator, which always judges whether the noise is filtered out. The generator is constantly changing the denoising way. To ensure the GAN model generates EEG signals stably, a new normalization method called sample entropy threshold and energy threshold-based (SETET) normalization is proposed to check the abnormal signals and limit the range of EEG signals. After the denoising system is established, although the denoising model uses the different subjects’ data for training, it can still apply to the new subjects’ data denoising. The experiments discussed in this paper employ the HaLT public dataset. Correlation and root mean square error (RMSE) are used as evaluation criteria. Results reveal that the proposed automatic GAN denoising network achieves the same performance as the manual hybrid artificial denoising method. Moreover, the GAN network makes the denoising process automatic, representing a significant reduction in time.
Journal Article
Association between Dysphagia and Frailty in Older Adults: A Systematic Review and Meta-Analysis
Background: Increasing bodies of epidemiological evidence indicate potential associations between dysphagia and the risk of frailty in older adults. We hypothesized that older adults with symptoms of dysphagia might have a higher prevalence of frailty or prefrailty than those without dysphagia. Methods: We systematically searched the PubMed, Embase, and Cochrane Library databases for relevant studies published through 20 April 2022. Cross-sectional and longitudinal studies that examined the associations between dysphagia and the existence of frailty or prefrailty in community-dwelling, facility-dwelling, or hospitalized adults aged 50 years or older were synthesized. The Newcastle–Ottawa Scale was used to evaluate study quality. Results: The meta-analysis comprised 12 cohorts, including 5,503,543 non-frailty participants and 735,303 cases of frailty or prefrailty. Random-effect meta-analysis demonstrated a significant association between dysphagia and the risk of frailty and prefrailty (OR, 3.24; 95% CI, 2.51–4.20). In addition, we observed consistent results across the subgroups and heterogeneity assessments. Conclusions: We propose including dysphagia assessment as a critical factor in the cumulative deficit model for identifying frailty in older adults. Understanding dysphagia and the potential role of nutritional supplements in older adults may lead to improved strategies for preventing, delaying, or mitigating frailty.
Journal Article
Diversity of immune checkpoints in cancer immunotherapy
Finding effective treatments for cancer remains a challenge. Recent studies have found that the mechanisms of tumor evasion are becoming increasingly diverse, including abnormal expression of immune checkpoint molecules on different immune cells, in particular T cells, natural killer cells, macrophages and others. In this review, we discuss the checkpoint molecules with enhanced expression on these lymphocytes and their consequences on immune effector functions. Dissecting the diverse roles of immune checkpoints in different immune cells is crucial for a full understanding of immunotherapy using checkpoint inhibitors.
Journal Article
Exosomes from adipose‐derived stem cells and application to skin wound healing
Skin wound healing is an intractable problem that represents an urgent clinical need. To solve this problem, a large number of studies have focused on the use of exosomes (EXOs) derived from adipose‐derived stem cells (ADSCs). This review describes the mechanisms whereby ADSCs‐EXOs regulate wound healing and their clinical application. In the wound, ADSCs‐EXOs modulate immune responses and inflammation. They also promote angiogenesis, accelerate proliferation and re‐epithelization of skin cells, and regulate collagen remodelling which inhibits scar hyperplasia. Compared with ADSCs therapeutics, ADSCs‐EXOs have highly stability and are easily stored. Additionally, they are not rejected by the immune system and have a homing effect and their dosage can be easily controlled. ADSCs‐EXOs can improve fat grafting and promote wound healing in patients with diabetes mellitus. They can also act as a carrier and combined scaffold for treatment, leading to scarless cutaneous repair. Overall, ADSCs‐EXOs have the potential to be used in the clinic to promote wound healing. This review describes the mechanisms whereby exosomes (EXOs) derived from adipose‐derived stem cells (ADSCs) regulate wound healing and their clinical application. In the wound, ADSCs‐EXOs modulate immune responses and inflammation, promote angiogenesis, accelerate proliferation and re‐epithelization of skin cells and regulate collagen remodelling, which inhibits scar hyperplasia. ADSCs‐EXOs have the potential to be used in the clinic, as they can improve fat grafting, promote wound healing of diabetic patients and act as a carrier and combined scaffold for treatment, leading to scarless cutaneous repair.
Journal Article
Roles of HLA-G/KIR2DL4 in Breast Cancer Immune Microenvironment
Human leukocyte antigen (HLA)-G is a nonclassical MHC Class I molecule, which was initially reported as a mediator of immune tolerance when expressed in extravillous trophoblast cells at the maternal-fetal interface. HLA-G is the only known ligand of killer cell immunoglobulin-like receptor 2DL4 (KIR2DL4), an atypical family molecule that is widely expressed on the surface of NK cells. Unlike other KIR receptors, KIR2DL4 contains both an arginine–tyrosine activation motif in its transmembrane region and an immunoreceptor tyrosine-based inhibitory motif (ITIM) in its cytoplasmic tail, suggesting that KIR2DL4 may function as an activating or inhibitory receptor. The immunosuppressive microenvironment exemplified by a rewired cytokine network and upregulated immune checkpoint proteins is a hallmark of advanced and therapy-refractory tumors. Accumulating evidence has shown that HLA-G is an immune checkpoint molecule with specific relevance in cancer immune escape, although the role of HLA-G/KIR2DL4 in antitumor immunity is still uncharacterized. Our previous study had shown that HLA-G was a pivotal mediator of breast cancer resistance to trastuzumab, and blockade of the HLA-G/KIR2DL4 interaction can resensitize breast cancer to trastuzumab treatment. In this review, we aim to summarize and discuss the role of HLA-G/KIR2DL4 in the immune microenvironment of breast cancer. A better understanding of HLA-G is beneficial to identifying novel biomarker(s) for breast cancer, which is important for precision diagnosis and prognostic assessment. In addition, it is also necessary to unravel the mechanisms underlying HLA-G/KIR2DL4 regulation of the immune microenvironment in breast cancer, hopefully providing a rationale for combined HLA-G and immune checkpoints targeting for the effective treatment of breast cancer.
Journal Article
Supramolecular catalyst with FeCl4 unit boosting photoelectrochemical seawater splitting via water nucleophilic attack pathway
Propelled by the structure of water oxidation co-catalysts in natural photosynthesis, molecular co-catalysts have long been believed to possess the developable potential in artificial photosynthesis. However, the interfacial complexity between light absorber and molecular co-catalyst limits its structural stability and charge transfer efficiency. To overcome the challenge, a supramolecular scaffold with the [FeCl
4
] catalytic units is reported, which undergo a water-nucleophilic attack of the water oxidation reaction, while the supramolecular matrix can be in-situ grown on the surface of photoelectrode through a simple chemical polymerization to be a strongly coupled interface. A well-defined BiVO
4
photoanode hybridized with [FeCl
4
] units in polythiophene reaches 4.72 mA cm
−2
at 1.23 V
RHE
, which also exhibits great stability for photoelectrochemical seawater splitting due to the restraint on chlorine evolution reaction by [FeCl
4
] units and polythiophene. This work provides a novel solution to the challenge of the interface charge transfer of molecular co-catalyst hybridized photoelectrode.
The strongly coupled interface between molecular catalysts and light absorbers is the key to solving efficient photoelectrochemical water oxidation. An in situ polymerized supramolecular-like catalyst was used to couple with BiVO4 for efficient and stable photoelectrochemical seawater splitting
Journal Article