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Solid–liquid lubrication systems have been widely used to enhance tribological behaviors. Alongside offering exceptional lubrication and wear-resistance performance, the active control of the tribological behavior of lubrication systems in accordance with service conditions is equally critical. To achieve this goal, accurately monitoring the condition of the lubrication system is fundamental. This review article aims to provide a fundamental understanding of different sensors for monitoring the condition of lubricants, as well as the friction and wear properties. Specifically, the sensors suitable for engineering applications are detailed introduced. Through this review, we wish to provide researchers in mechanical engineering with a clear technical overview, which can guide the design of intelligent lubrication systems with suitable sensors.

Background Hepatocellular carcinoma (HCC) is a common liver malignancy with limited treatment options. Previous studies expressed the potential synergy of sorafenib and NK cell immunotherapy as a promising approach against HCC. MRI is commonly used to assess response of HCC to therapy. However, traditional MRI-based metrics for treatment efficacy are inadequate for capturing complex changes in the tumor microenvironment, especially with immunotherapy. In this study, we investigated potent MRI radiomics analysis to non-invasively assess early responses to combined sorafenib and NK cell therapy in a HCC rat model, aiming to predict multiple treatment outcomes and optimize HCC treatment evaluations. Methods Sprague Dawley (SD) rats underwent tumor implantation with the N1-S1 cell line. Tumor progression and treatment efficacy were assessed using MRI following NK cell immunotherapy and sorafenib administration. Radiomics features were extracted, processed, and selected from both T1w and T2w MRI images. The quantitative models were developed to predict treatment outcomes and their performances were evaluated with area under the receiver operating characteristic (AUROC) curve. Additionally, multivariable linear regression models were constructed to determine the correlation between MRI radiomics and histology, aiming for a noninvasive evaluation of tumor biomarkers. These models were evaluated using root-mean-squared-error (RMSE) and the Spearman correlation coefficient. Results A total of 743 radiomics features were extracted from T1w and T2w MRI data separately. Subsequently, a feature selection process was conducted to identify a subset of five features for modeling. For therapeutic prediction, four classification models were developed. Support vector machine (SVM) model, utilizing combined T1w + T2w MRI data, achieved 96% accuracy and an AUROC of 1.00 in differentiating the control and treatment groups. For multi-class treatment outcome prediction, Linear regression model attained 85% accuracy and an AUC of 0.93. Histological analysis showed that combination therapy of NK cell and sorafenib had the lowest tumor cell viability and the highest NK cell activity. Correlation analyses between MRI features and histological biomarkers indicated robust relationships (r = 0.94). Conclusions Our study underscored the significant potential of texture-based MRI imaging features in the early assessment of multiple HCC treatment outcomes.

We previously demonstrated that for long-term spastic limb paralysis, transferring the seventh cervical nerve (C7) from the nonparalyzed side to the paralyzed side results in increase of 17.7 in Fugl-Meyer score. One strategy for further improvement in voluntary arm movement is selective activation of five target muscles innervated by C7 during recovery process. In this study, we develop an implantable multisite optogenetic stimulation device (MOSD) based on shape-memory polymer. Two-site stimulation of sciatic nerve bundles by MOSD induces precise extension or flexion movements of the ankle joint, while eight-site stimulation of C7 nerve bundles induce selective limb movement. Long-term implant of MOSD to mice with severed and anastomosed C7 nerve is proven to be both safe and effective. Our work opens up the possibility for multisite nerve bundle stimulation to induce highly-selective activations of limb muscles, which could inspire further applications in neurosurgery and neuroscience research. Optogenetic stimulation of damaged peripheral nerves has advantages over electrical stimulation but it’s limited to single-site stimulation. Here the authors develop a spiral-shaped LED implant for precise optogenetic stimulation of peripheral nerve bundles at multiple sites and use it to induce distinct limb movements in mice.

Background Heterogeneity of hepatocellular carcinoma (HCC) presents significant challenges for therapeutic strategies and necessitates combinatorial treatment approaches to counteract suppressive behavior of tumor microenvironment and achieve improved outcomes. Here, we employed cytokines to induce memory-like behavior in natural killer (NK) cells, thereby enhancing their cytotoxicity against HCC. Additionally, we evaluated the potential benefits of combining sorafenib with this newly developed memory-like NK cell ( p NK) immunochemotherapy in a preclinical model. Methods HCC tumors were grown in SD rats using subcapsular implantation. Interleukin 12/18 cytokines were supplemented to NK cells to enhance cytotoxicity through memory activation. Tumors were diagnosed using MRI, and animals were randomly assigned to control, p NK immunotherapy, sorafenib chemotherapy, or combination therapy groups. NK cells were delivered locally via the gastrointestinal tract, while sorafenib was administered systemically. Therapeutic responses were monitored with weekly multi-parametric MRI scans over three weeks. Afterward, tumor tissues were harvested for histopathological analysis. Structural and functional changes in tumors were evaluated by analyzing MRI and histopathology data using ANOVA and pairwise T-test analyses. Results The tumors were allowed to grow for six days post-cell implantation before treatment commenced. At baseline, tumor diameter averaged 5.27 mm without significant difference between groups ( p  = 0.16). Both sorafenib and combination therapy imposed greater burden on tumor dimensions compared to immunotherapy alone in the first week. By the second week of treatment, combination therapy had markedly expanded its therapeutic efficacy, resulting in the most significant tumor regression observed (6.05 ± 1.99 vs. 13.99 ± 8.01 mm). Histological analysis demonstrated significantly improved cell destruction in the tumor microenvironment associated with combination treatment (63.79%). Interestingly, we observed fewer viable tumor regions in the sorafenib group (38.9%) compared to the immunotherapy group (45.6%). Notably, there was a significantly higher presence of NK cells in the tumor microenvironment with combination therapy (34.79%) compared to other groups (ranging from 2.21 to 26.50%). Although the tumor sizes in the monotherapy groups were similar, histological analysis revealed a stronger response in p NK cell immunotherapy group compared to the sorafenib group. Conclusions Experimental results indicated that combination therapy significantly enhanced treatment response, resulting in substantial tumor growth reduction in alignment with histological analysis.

Single-cell RNA sequencing (scRNA-seq) technologies are used to characterize the heterogeneity of cells in cell types, developmental stages and spatial positions. The rapid accumulation of scRNA-seq data has enabled single-cell-type labelling to transform single-cell transcriptome analysis. Here we propose an interpretable deep-learning architecture using capsule networks (called scCapsNet). A capsule structure (a neuron vector representing a set of properties of a specific object) captures hierarchical relations. By utilizing competitive single-cell-type recognition, the scCapsNet model is able to perform feature selection to identify groups of genes encoding different subcellular types. The RNA expression signatures, which enable subcellular-type recognition, are effectively integrated into the parameter matrices of scCapsNet. This characteristic enables the discovery of gene regulatory modules in which genes interact with each other and are closely related in function, but present distinct expression patterns. The wealth of data gathered from single-cell RNA sequencing can be processed with deep learning techniques, but often those methods are too opaque to reveal why a single cell is labelled to be a certain cell type. Lifei Wang and colleagues present an RNA-sequencing analysis method that uses capsule networks and is interpretable enough to allow for identification of cell-type-specific genes.

To evaluate the slip resistance of high-strength bolted friction-type connections subjected to different corrosion-protection treatments, calibration tests were performed on six representative faying-surface conditions: sand-blasted (uncoated), epoxy zinc-rich primer, waterborne inorganic zinc-rich coating, alcohol-soluble inorganic anti-corrosion anti-slip primer, a complete multi-layer protective coating system, and cold galvanizing. Fifteen test groups comprising 45 tensile specimens were examined to determine slip factors, which were then compared with values recommended in domestic and international design standards. The results show that sand-blasted surfaces (W type) exhibit stable slip factors of μ = 0.43–0.45; alcohol-soluble inorganic primer surfaces (S type) provide the highest slip resistance with μ = 0.49–0.51, representing an increase of approximately 13%–18% compared with sand-blasted surfaces; and cold-galvanized surfaces (D type) achieve favourable performance with μ ≈ 0.44. Waterborne inorganic zinc-rich surfaces (A type) yield μ ≈ 0.33, corresponding to a reduction of about 25%, and are suitable for non-slip-critical connections. In contrast, epoxy zinc-rich primers (C type) and complete multi-layer coating systems (X type) present lower slip factors of μ = 0.26–0.28 and μ ≈ 0.23, corresponding to reductions of approximately 35%–45% and about 50%, respectively, indicating that the X-type treatment is unsuitable for slip-critical applications. The influence of bolt diameter is limited, with slip-factor variations within 5%–8% under the same surface condition, and no statistically significant effect confirmed by two-way ANOVA. These findings provide a quantitative experimental basis for the design, classification, and future standardization of friction-type bolted connections with coated faying surfaces.

Background Acute and early HIV (AEH) infection is characterized by a high viral load and infectivity. Approximately 50% of cases of HIV-1 transmission occur during AEH. Understanding sexual behaviour trajectories would be useful for predicting changes in the risk of HIV acquisition. However, few studies have investigated sexual behaviour trajectories and their association with AEH acquisition. This study identified behaviour trajectories among men who have sex with men (MSM), determined the risk of AEH infection, and compared risk factors between different behaviour trajectories. Methods The study was based on an ongoing prospective open cohort of voluntary HIV counselling and testing (VHCT) among MSM in Tianjin, China. From 2011 to 2019, 1974 MSM were recruited. Group-based trajectory modelling (GBTM) was used to identify behaviour trajectories by constructing a sexual risk behaviour score. Logistic regression and generalized estimating equation (GEE) were used to compare the risk of AEH infection and risk factors for different behaviour trajectories. All data analyses were performed using SAS 9.4. Results The incidence of AEH infection was 1.76/100 person-years, with 64 AEH infections documented in 3633 person-years of follow-up. Three sexual behaviour trajectories were identified: CL (consistently low risk, 35.46%), CH (consistently high risk, 42.71%) and HTL (high to low risk, 21.83%). MSM in the HTL and CH groups had higher AEH infection rates than MSM in the CL group (6.73%, 3.08% and 1.28%, respectively), with ORs of 5.54 (2.60, 11.82) and 2.44 (1.14, 5.25), respectively. MSM aged 30–50 years old and MSM who underwent HIV testing in the last year were more likely to be in the CH group and HTL group. In addition, the HTL group was characterized by a lower likelihood of local registration and a higher likelihood of working as a MSW. Conclusion MSM in the CH group and the HTL group had a higher risk of AEH infection. In the future, VHCT should be performed more often among younger MSM, and HIV counselling should be given the same priority as HIV testing. In addition, VHCT combined with PrEP may have a better preventive impact on MSM with a high risk of AEH infection.

Wireless networks of implantable electronic sensors and actuators at the microscale (sub-mm) level are being explored for monitoring and modulation of physiological activity for medical diagnostics and therapeutic purposes. Beyond the requirement of integrating multiple electronic or chemical functions within small device volumes, a key challenge is the development of high-throughput methods for the implantation of large numbers of microdevices into soft tissues with minimal damage. To that end, we have developed a method for high-throughput implantation of ~100–200 µm size devices, which are here simulated by proxy microparticle ensembles. While generally applicable to subdermal tissue, our main focus and experimental testbed is the implantation of microparticles into the brain. The method deploys a scalable delivery tool composed of a 2-dimensional array of polyethylene glycol-tipped microneedles that confine the microparticle payloads. Upon dissolution of the bioresorbable polyethylene glycol, the supporting array structure is retrieved, and the microparticles remain embedded in the tissue, distributed spatially and geometrically according to the design of the microfabricated delivery tool. We first evaluated the method in an agarose testbed in terms of spatial precision and throughput for up to 1000 passive spherical and planar microparticles acting as proxy devices. We then performed the same evaluations by implanting particles into the rat cortex under acute conditions and assessed the tissue injury produced by our method of implantation under chronic conditions.Neural interfaces: A high-throughput method for implanting microdevicesA low-injury, high-throughput technique to embed neural interfaces into brain tissue brings the idea of a ‘smart body’ closer to home. While some research groups focus on miniaturizing sensors and bio-actuators to implantable sizes, Brown University’s Stefan Sigurdsson and a team of US researchers have developed a technique to embed these devices into cortical tissue. In their method, microparticles (used in lieu of functional implants) are suspended in super-thin needles of polyethylene glycol, which are driven into the brain at high speed to minimize tissue damage. The polyethylene glycol is absorbed into the brain and the injection apparatus is removed, leaving the implants behind. The method can be scaled for rapid implantation of high numbers of devices and could see use in the development of human-computer integrations.

Carbon fiber composite performance relies on the fiber‐matrix interface for effective load transfer. To enhance interfacial properties between the fiber and matrix, often carbon fiber surfaces are oxidatively and covalently modified to incorporate chemical functional groups. By contrast, here, noncovalent electrodeposition of functional polyelectrolyte is applied onto conducting carbon fibers from aqueous solutions. A natural polymer, chitosan (CS), is electro‐deposited onto the fiber surface, which undergoes multi‐scale physical interactions. The bound CS layer with abundant amine functionalities reacts with epoxy moieties within the matrix to improve the interfacial properties. The scalable and energy‐efficient electrodeposition eliminates traditional functionalization and sizing requirements of carbon fiber while delivering significantly higher mechanical performance with enhanced consistency. For continuous fiber reinforced composites, compared to conventional fibers, apparent interlaminar shear strength increases by 27%, reaching ≈86 MPa. The short fiber composites with only 2–11 wt.% fibers exhibit ≈20% increase in tensile strength with a peak performance of 120 MPa. Unlike traditionally treated and sized carbon fiber, this approach delivers coated fibers with long shelf‐life and allows recovery of both CS in electrolyte form and carbon fiber by continuous electrochemical processing of the modified fibers with inverse polarity; thus, it promotes overall fiber recyclability. Chitosan is electrodeposited onto the surface of carbon fibers in an energy‐efficient and simplified procedure, enhancing interfacial bonding potential with various epoxy matrices. The coated fibers effectively function as reinforcing fillers in both continuous and discontinuous states. Furthermore, the chitosan coating has a long shelf‐life, and it can be reversibly removed by continuous operation, enabling the recycling of carbon fibers.

BackgroundThe HIV epidemic in key populations such as men who have sex with men (MSM) is a public health issue of worldwide concern. China has seen an increase in newly diagnosed HIV infections through male–male sexual contact in the past decade. In a long-term cohort, how the complex behaviour pattern of MSM changed and the association with the HIV risk are unclear at present.MethodsThis study was conducted from October 2011 to December 2019 in Tianjin. MSM were recruited by snowball sampling through online and offline ways. Demographic and sexual behavioural data were collected for analysis. Three indicators (condom use in last anal sex, frequency of condom use during anal sex and the number of sexual partners) were used to define the behaviour change. Participants with zero, one, and two or three risk indicators were categorised into behaviour types of ‘protective’, ‘moderate’, and ‘fragile’, respectively. Change in behaviour type between baseline and each visit was considered. Time-varying Cox models were performed to evaluate HIV infection risk.ResultsOf 2029 MSM included in the study, 127 were new HIV diagnoses. The overall incidence rate was 3.36 per 100 person-years. The percentage of ‘protective’ and ‘moderate’ behaviour types had a conspicuous growth trend as the follow-up. Furthermore, the HIV incidence rate in each visit among different behaviour transition types showed a general downward trend as the number of total follow-up times increased. Individuals who remained in ‘fragile’ (adjusted HR (aHR): 25.86, 95% CI: 6.92 to 96.57) or changed from ‘protective’ to ‘moderate’ (aHR: 4.79, 95% CI: 1.18 to 19.47), ‘protective’ to ‘fragile’ (aHR: 23.03, 95% CI: 6.02 to 88.13), and ‘moderate’ to ‘fragile’ (aHR: 25.48, 95% CI: 6.79 to 95.40) between baseline and the last follow-up had a higher HIV risk. Gained risk indicators were associated with the increase of HIV risk (gained one indicator, aHR: 2.67, 95% CI: 1.68 to 4.24; gained two or three indicators, aHR: 4.99, 95% CI: 3.00 to 8.31) while losing just one risk indicator could halve the risk (aHR: 0.43, 95% CI: 0.21 to 0.90).ConclusionsAmong MSM in Tianjin, it is necessary to get timely behaviour change for those with high-incidence behaviour patterns while sustaining for those with low-incidence patterns.Trial registration numberChinese Clinical Trials Registry (ChiCTR2000039500).