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Precipitation hardening has been recently validated as a new mechanism for domain wall pinning and mechanical loss reduction in piezoelectrics. While anisometric precipitates have high pinning strengths, there is limited knowledge about the electrical anisotropy of the precipitation-hardened piezoceramics. In the present work, we successfully orient the precipitates in Li 0.18 Na 0.82 NbO 3 piezoceramics by applying a uniaxial stress during the aging and studied its electrical anisotropy. Predicted by mechanical simulation and verified by transmission electron microscopy, it is demonstrated that the precipitate variant with its long axis perpendicular to the applied stress is energetically favored. The electrical anisotropy of the stress-assisted aged Li 0.18 Na 0.82 NbO 3 is studied by applying electrical fields parallel or perpendicular to the stress axis. The domain wall contribution to permittivity is found to vary by more than a factor of two depending on orientation. In addition, the domain walls are more difficult to be activated by increasing the temperature when the electric field is perpendicular to the stress axis. Our work highlights the precipitate variant selection induced by stress-assisted aging and the related electrical anisotropy in piezoceramics. This technique enables the precipitate orientation in piezoceramics and the utilization of its anisotropy, providing fundamental insight into precipitate-domain-wall interactions and setting the ground for leveraging precipitation hardening effect in piezoceramics., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Objective: This study aims to investigate the feasibility and effectiveness of enhanced recovery after surgery (ERAS) in HIV-positive patients diagnosed with osteonecrosis of the femoral head (ONFH) undergoing total hip replacement (THR)., Methods: We retrospectively included 80 HIV-positive patients diagnosed with ONFH who underwent THR between 2011 and 2022. Forty patients treated before August 2019 constituted the control group, receiving standard antiviral regimens and traditional perioperative management pathways. The remaining 40 patients, treated after August 2019, formed the study group, which followed the ERAS protocol. This protocol emphasized the use of more effective antiviral medications, rapid viral load reduction, immune enhancement, improved nutritional status, control of co-infections, prophylactic antibiotics, and anti-osteoporosis measures. We recorded patients' general status and imaging examinations before surgery, as well as detailed perioperative management strategies, antiviral regimens, durations, and immunological indicators for both groups. Targeted and standardized treatment measures were applied to the ERAS group, allowing for a comparison of the efficacy of perioperative management between the two patient groups., Results: Preoperative nutritional and immune indicators were lower in the control group than in the study group, while inflammatory markers were higher. Postoperatively, immune, nutritional, and inflammatory indicators were significantly better in the ERAS group compared to the control group. Following antiviral treatment, the viral load was predominantly undetectable in the ERAS group (target not detected, TND). Comprehensive measures minimized complications in the ERAS group (P = 0.028, P < 0.05). The hospitalization duration for the ERAS group was significantly shorter than that of the control group, with both groups showing marked improvement compared to preoperative conditions and no incidents of loosening or dislocation., Conclusion: Strengthening antiviral treatment, anti-infective strategies, incision care, and nutritional support effectively prevents and reduces complications such as delayed wound healing in HIV-positive patients. The implementation of ERAS measures requires careful attention to the patient's immune status, close monitoring of clinical changes, and timely adjustments to treatment and care plans., Level of Evidence: Treatment studies., Competing Interests: Declarations. Ethics approval and consent to participate: This study did not require ethics and dissertation committee's permission and approval because it was a retrospective study and the patient information involved were patients who had been previously seen in our department, whose information was collected from our department’s electronic system, which did not involve ethics and morals or patient privacy and did not require obtaining patients' informed consent for this study. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

This study investigated factors influencing death in patients with Acute Kidney Injury (AKI) and developed models to predict their mortality risk. We analyzed data from 1079 AKI patients admitted to Changsha First Hospital using a retrospective design. Patient information including demographics, medical history, lab results, and treatments were collected. Logistic regression models were built to identify risk factors and predict 90-day and 1-year mortality. The 90-day mortality rate among 1079 AKI patients was 13.8% (149/1079) and the one-year mortality rate was 14.8% (160/1079). For both 90-day and 1-year mortality in patients with AKI, age over 60, anemia, hypotension, organ failure, and an admission Scr level above 682.3 μmol/L were identified as independent risk factors through multivariate logistic regression analysis. Additionally, mechanical ventilation was associated with an increased risk of death at one year. To ensure the generalizability of the models, we employed a robust 5-fold cross-validation technique. Both the 90-day and 1-year mortality models achieved good performance, with area under the curve (AUC) values exceeding 0.8 in the training set. Importantly, the AUC values in the validation set (0.828 for 90-day and 0.796 for 1-year) confirmed that the models' accuracy holds true for unseen data. Additionally, calibration plots and decision curves supported the models' usefulness in predicting patient outcomes. The logistic regression models built using these factors effectively predicted 90-day and 1-year mortality risk. These findings can provide valuable insights for clinical risk management in AKI patients., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The use of artificial intelligence (AI) in high-resolution computed tomography (HRCT) for diagnosing systemic sclerosis-associated interstitial lung disease (SSc-ILD) is relatively limited. This study aimed to analyse lung HRCT images of patients with systemic sclerosis with interstitial lung disease (SSc-ILD) using artificial intelligence (AI), conduct correlation analysis with clinical manifestations and prognosis, and explore the features and prognosis of SSc-ILD. Overall, 72 lung HRCT images and clinical data of 58 patients with SSC-ILD were collected. ILD lesion type, location, and volume on HRCT images were identified and evaluated using AI. The imaging characteristics of diffuse SSC (dSSc)-ILD and limited SSc-ILD (lSSc-ILD) were statistically analysed. Furthermore, the correlations between lesion type, clinical indicators, and prognosis were investigated. dSSc and lSSc were more prevalent in patients with a disease duration of < 1 and ≥ 5 years, respectively. SSc-ILD mainly comprises non-specific interstitial pneumonia (NSIP), usual interstitial pneumonia (UIP), and unclassifiable idiopathic interstitial pneumonia. HRCT reveals various lesion types in the early stages of the disease, with an increase in the number of lesion types as the disease progresses. Lesions appearing as grid, ground-glass, and nodular shadows were dispersed throughout both lungs, while those appearing as consolidation shadows and honeycomb were distributed across the lungs. Ground-glass opacity lesion type was absent on HRCT images of patients with SSc-ILD and pulmonary hypertension. This study showed that AI can efficiently analyse imaging characteristics of SSc-ILD, demonstrating its potential to learn from complex images with high generalisation ability., (© 2024. The Author(s).)

Water scarcity poses a significant challenge for people living in arid areas. Despite the effectiveness of many bioinspired surfaces in promoting vapor condensation, their water-harvesting efficiency is insufficient. This is often exacerbated by overheating, which decreases the performance in terms of the micro-droplet concentration and movement on surfaces. In this study, we used a spotted amphiphilic surface to enhance the surfaces' water-harvesting efficiency while maintaining their heat emissivity. Through hydrophilic particle screening and hydrophobic groove modifying, the coalescence and sliding characteristics of droplets on the amphiphilic surfaces were improved. The incorporation of boron nitride (BN) nanoparticles further enhanced the surfaces' ability to harvest energy from condensation. To evaluate the water-harvesting performance of these amphiphilic surfaces, we utilized a real-time recording water-harvesting platform to identify microscopic weight changes on the surfaces. Our findings indicated that the inclusion of glass particles in hydrophobic grooves, combined with 1.0 wt.% BN nanoparticles, enhanced the water-harvesting efficiency of the amphiphilic surfaces by more than 20%.

This article solves the cooperative adaptive tracking control problem for nonlinear pure-feedback multi-agent systems (MASs). Compared with the previous achievements of adaptive control of pure-feedback MASs, the partial derivative of the nonaffine function may not exist by using decoupling technology. In the controller design framework based on the backstepping technique, the additional state variables are processed using the special properties of the radial basis function neural networks (RBF NNs). A special-shaped Laplacian matrix is proposed to unify the leader gain form in the tracking error design process (the coefficient in the second term of tracking error). Furthermore, an event trigger mechanism (ETM) is introduced to save resources. The constructed controller under the ETM can not only stabilize the system states but also make the tracking error reach a small accuracy. Finally, the simulation results demonstrated the feasibility of the proposed method.

Flexible all-solid-state lithium-carbon dioxide batteries (FASSLCBs) are recognized as a next-generation energy storage technology by solving safety and shuttle effect problems. However, the present FASSLCBs rely heavily on high-temperature operation due to sluggish solid-solid-gas multiphase mass transfer and unclear capacity degradation mechanism. Herein, we designed bicontinuous hierarchical porous structures (BCHPSs) for both solid polymer electrolyte and cathode for FASSLCBs to facilitate the mass transfer in all connected directions. The formed large Lewis acidic surface effectively promotes the lithium salt dissociation and the CO 2 conversion. Furthermore, it is unraveled that the battery capacity degradation originates from the "dead Li 2 CO 3 " formation, which is inhibited by the fast decomposition of Li 2 CO 3 . Accordingly, the assembled FASSLCBs exhibit an excellent cycling stability of 133 cycles at 60 °C, which is 2.7 times longer than that without BCHPSs, and the FASSLCBs can be operated repeatedly even at room temperature. This BCHPS method and fundamental deactivation mechanism provide a perspective for designing FASSLCBs with long cycling life.

Polythioureas (PTUs) show great potentials for applications in the new generation of film capacitors due to their excellent dielectric properties. Herein, the cis-trans copolymer chain of PTU is successfully tailored by employing cis and trans cyclohexyl spacers. The relationship between the copolymer chain conformation, microstructure, and dielectric properties is carefully explored by a series of analysis. Compared with cis conformation, the trans with less steric hindrance can promote the formation of H-bonds. The enhanced H-bonding interactions not only reduce the molecular inter-chain spacing, but also drive the self-assembly of molecular chains to form cylindrical and droplet nano-morphologies. The phase separation between cis and trans PTUs is confirmed by combining the experimental results of TEM and DSC, and the CT64-PTU with the most two-phase interface thus obtains the highest permittivity of 5.5 (@10 Hz). The reduced molecular inter-chain spacing is accompanied by a decreased hopping distance of charges, which improves breakdown strength by 17% from 498 MV/m to 580 MV/m. Therefore, the cis-trans copolymer chain conformation in PTU provides a simultaneous high permittivity and breakdown strength. This research offers a strategy to further design high-performance dielectrics via regulation of copolymer chain conformation., (© 2023 Wiley-VCH GmbH.)

Electrical breakdown is an important physical phenomenon in power equipment and electronic devices. Recently, the mechanism of AC and DC breakdown has been preliminarily revealed as electrode-dielectric interface breakdown and bulk breakdown, respectively, based on space charge dynamics through numerical calculations. However, the AC breakdown mechanism still lacks enough direct experimental support, which restricts further understanding and the design and development of electrical structures. Here, in this study, LDPE films with various thicknesses ranging from 33 μm to 230 μm were surface modified with ozone for different durations to experimentally investigate DC and AC breakdown mechanism. The results indicate that carbonyl groups (C=O) were introduced onto the film surface, forming shallow surface traps and leading to a decreased average trap depth and an increased trap density. Such a surface oxidation modulated trap distribution led to enhanced space charge injection and bulk electrical field distortion, which decreased DC breakdown strength as the oxidation duration went longer, in all film thicknesses. However, such decreases in breakdown strength occurred only in films below 55 μm under AC stresses, as the enhanced electrical field distortion at the electrode-dielectric interface was more obvious and dominating in thin films. These experimental results further confirm the proposed electrode-dielectric interface breakdown of dielectric films and provide new understandings of space charge modulated electrical breakdown, which fulfills dielectric breakdown theory and benefits the miniaturization of power equipment and electronic devices.

Objective: To investigate the efficacy of treating patients with HIV-positive osteonecrosis of the femoral head using drilled decompression autologous bone marrow and allogeneic bone grafting., Methods: 40 patients (44 hips) with early osteonecrosis of the femoral head treated by drilling decompression autologous bone marrow and allogeneic bone grafting since October 2015 were retrospectively analyzed, among which 20 patients (24 hips) were HIV-positive patients with early osteonecrosis of the femoral head, 16 males and 4 females, age 22-43 years, average 39.6 ± 10.18 years, and 20 patients (20 hips) in the same period HIV-negative early osteonecrosis of the femoral head patients, 13 males and 7 females, aged 48-78 years, mean 63.50 ± 7.94 years were negative controls. General information including ARCO stage, Harris score, VAS score, hematological indexes including CD4 + T lymphocyte count, and HIV viral load was recorded for all patients before surgery. All patients were operated on by drilling and decompression of the necrotic area, harvesting autologous iliac bone marrow with allogeneic bone, and bone grafting through the decompression channel. The patients were followed up regularly at 6, 12, and 24 months after surgery and annually thereafter, and the repair of the necrotic femoral head was observed by reviewing the frontal and lateral X-ray, CT or MRI of the hip joint, and the complications and functional recovery of the hip joint was counted and compared between the two groups., Results: All patients were followed up, and the ARCO stages in the HIV-positive group were stage I 2 hips, stage IIA 6 hips, stage IIB 8 hips, stage IIC 6 hips, and stage III 2 hips, with a follow-up time of 12 to 60 months and a mean of 24.6 months. In the negative control group, there were 3 hips in ARCO stage I, 7 hips in stage IIA, 5 hips in stage IIB, 3 hips in stage IIC, and 2 hips in stage III, and the follow-up time ranged from 13 to 62 months, with an average of 24.8 months. The Harris score and VAS score of the hip in both groups improved significantly at 6 months postoperatively compared with those before surgery (P < 0.001). The difference between the Harris score of the hip in the positive group at 24 months postoperatively compared with that at 6 months postoperatively was statistically significant, but the VAS score at 24 months postoperatively compared with that at 6 months postoperatively was not statistically significant. In the negative group, there was no statistically significant difference in the Harris score and VAS score of the hip at 24 months postoperatively compared with those at 6 months postoperatively. In the positive group, there was a trend of continuous increase in hip BMD from the beginning of the postoperative period (P < 0.001). There was no statistically significant difference between the negative group and the positive group at the 24 months postoperatively follow-up except for the Harris score, which was statistically significant (P < 0.001), and the VAS score, which was statistically insignificant. At the 24 months postoperatively follow-up, patients in both groups had good recovery of hip function, and no complications such as vascular and nerve injury and fracture occurred during the perioperative period and follow-up period, and no complications related to incisional infection and pulmonary infection occurred during hospitalization., Conclusion: The treatment of early HIV-positive osteonecrosis of the femoral head patients with autologous bone marrow and allogeneic bone grafting by drilling and decompression to remove the tissue in the necrotic area of the femoral head can effectively stop the process of osteonecrosis of the femoral head and promoting femoral head repair in HIV-positive patients is a safe and effective method for treating HIV-positive patients with early osteonecrosis of the femoral head, and can effectively delay or postpone total hip replacement in patients., (© 2023. The Author(s).)

Dielectric materials with high surface electric insulation strength are in great demand in a high-power space solar cell array (SSCA). A moderately conductive surface is favorable to inhibit charge accumulation and mitigate electric field distortion, thus improving the surface flashover voltage. Although numerous modification methods have been proposed to achieve this goal, the facile, efficient, scalable, and environmentally friendly modification strategy remains a critical challenge to date. Considering the excellent charge modulation ability of ZnO and its mild preparation conditions, a facile and economical hydrothermal strategy was proposed to fabricate in situ a durable poly(ether imide)/zinc oxide (PEI/ZnO) coating with a high charge decay rate. The blooming flower-like ZnO in the coating is proved to play a key role in enhancing lateral charge dissipation on the surface of PEI, thereby suppressing surface charge accumulation. It was also shown that the shielding effect of ZnO on high-energy photons during flashover and the catalytic effect of Zn 2+ on PEI molecular chains during hydrothermal treatment had a facilitating and suppressing effect on outgassing, respectively, and consequently affected the flashover. Excitingly, the synergistic effects of both accelerated charge dissipation and suppressed outgassing helped to improve the flashover voltage of PEI by up to 36.7%. The strategy selected here is efficient, scalable, and facile, and the coating is durable, which makes sense for commercial promotion.

A series of chalcogen-doped nanographenes (NGs) and their oxides are described. Their molecular design is conceptually based on the insertion of different chalcogens into the hexa- peri -hexabenzocoronene (HBC) backbone. All the NGs adopt nonplanar conformations, which would show better solubility compared to planar HBC. Except for the oxygen-doped, saddle-shaped NG, the insertion of large chalcogens like sulfur and selenium leads to a seco -HBC-based, helical geometry. All the three-dimensional structures are unambiguously confirmed by single-crystal X-ray diffractometry. Their photophysical properties including UV-vis absorption, fluorescence, chiroptical, charge distribution, and orbital gaps are investigated experimentally or theoretically. The properties of each structure are significantly affected by the doped chalcogen and its related oxidative state. Notably, upon heating or adding an acid, the selenium-doped NG or its oxide undergoes a selenium extrusion reaction to afford seco -HBC or HBC quantitatively, which can be treated as precursors of hydrocarbon HBCs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Purpose: It is well known that the CD4/CD8 ratio is a special immune-inflammation marker. We aimed to explore the relationship between the CD4/CD8 ratio and the risk of surgical site infections (SSI) among human immunodeficiency virus (HIV)-positive adults undergoing orthopedic surgery., Methods: We collected and analyzed data from 216 HIV-positive patients diagnosed with fractures at the department of orthopedics, Beijing Ditan Hospital between 2011 and 2019. The demographic, surgical, and hematological data for all patients were collected in this retrospective cohort study. We explored the risk factors for SSI using univariate and multivariate logistic regression analysis. Then, the clinical correlation between the CD4 count, CD4/CD8 ratio, and SSI was studied using multivariate logistic regression models after adjusting for potential confounders. Furthermore, the association between the CD4/CD8 ratio and SSI was evaluated on a continuous scale with restricted cubic spline (RCS) curves based on logistic regression models., Results: A total of 23 (10.65%) patients developed SSI during the perioperative period. Patients with hepatopathy (OR=6.10, 95%CI=1.46-28.9), HIV viral load (OR=8.68, 95%CI=1.42-70.2; OR=19.4, 95%CI=3.09-179), operation time (OR=7.84, 95%CI=1.35-77.9), and CD4 count (OR=0.05, 95%CI=0.01-0.23) were risk factors for SSI (P-value < 0.05). Our study demonstrated that a linear relationship between CD4 count and surgical site infection risk. In other words, patients with lower CD4 counts had a higher risk of developing SSI. Furthermore, the relationship between CD4/CD8 ratio and SSI risk was non-linear, inverse 'S' shaped. The risk of SSI increased substantially when the ratio was below 0.913; above 0.913, the risk of SSI was almost unchanged. And there is a 'threshold-saturation' effect between them., Conclusion: Our research shows the CD4/CD8 ratio could be a useful predictor and immune-inflammation marker of the risk of SSI in HIV-positive fracture patients. These results, from a Chinese hospital, support the beneficial role of immune reconstitution in HIV-positive patients prior to orthopedic surgery., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Liu, Li, Li, Zhao and Zhang.)

The past decade witnessed remarkable success in synthetic molecular nanographenes. Encouraged by the widespread application of chiral nanomaterials, the design, and construction of chiral nanographenes is a hot topic recently. As a classic nanographene unit, hexa- peri -hexabenzocoronene generally serves as the building block for nanographene synthesis. This review summarizes the representative examples of hexa- peri -hexabenzocoronene-based chiral nanographenes., (Copyright © 2023, Li et al.)

The rheological behaviors of low-density polyethylene doped with additives (PEDA) determine the dynamic extrusion molding and structure of high-voltage cable insulation. However, the coupling effect of additives and molecular chain structure of LDPE on the rheological behaviors of PEDA is still unclear. Here, for the first time, the rheological behaviors of PEDA under uncross-linked conditions are revealed by experiment and simulation analysis, as well as rheology models. The rheology experiment and molecular simulation results indicate that additives can reduce the shear viscosity of PEDA, but the effect degree of different additives on rheological behaviors is determined by both chemical composition and topological structure. Combined with experiment analysis and the Doi-Edwards model, it demonstrates that the zero-shear viscosity is only determined by LDPE molecular chain structure. Nevertheless, different molecular chain structures of LDPE have different coupling effects with additives on the shear viscosity and non-Newtonian feature. Given this, the rheological behaviors of PEDA are predominant by the molecular chain structure of LDPE and are also affected by additives. This work can provide an important theoretical basis for the optimization and regulation of rheological behaviors of PEDA materials used for high-voltage cable insulation.

Distributed fiber optic sensors (DFOS) can detect structural cracks and structural deformation with high accuracy and wide measurement range. This study monitors the segmental prestressed bent cap, assembled with a large key dry joint, based on optical fiber technology, and it allows the comparison of its damaging process with that of a monolithic cast in place counterpart. The obtained results, comprising cross-section strain distributions, longitudinal strain profiles, neutral axis location, crack pattern, and the damage process, show that the DFOS technology can be successfully used to analyze the complex working stress state of the segmental beam with shear key joints, both in the elastic range and at the ultimate load, and to successfully identify the changing characteristics of the stress state of the segmental capping beam model when elastic beam theory no longer applies. The DFOS data confirm that the shear key joint, as the weak point of the segmental cap beam, results in the high stress concentration area, and the damage rate is higher than that of the cast-in-place beam. The accurate monitoring by the DFOS allows for the realization that the damage occurs at the premature formation of a concentrated compression zone on the upper part of the shear key.

For capacitive energy storage at elevated temperatures 1-4 , dielectric polymers are required to integrate low electrical conduction with high thermal conductivity. The coexistence of these seemingly contradictory properties remains a persistent challenge for existing polymers. We describe here a class of ladderphane copolymers exhibiting more than one order of magnitude lower electrical conductivity than the existing polymers at high electric fields and elevated temperatures. Consequently, the ladderphane copolymer possesses a discharged energy density of 5.34 J cm -3 with a charge-discharge efficiency of 90% at 200 °C, outperforming the existing dielectric polymers and composites. The ladderphane copolymers self-assemble into highly ordered arrays by π-π stacking interactions 5,6 , thus giving rise to an intrinsic through-plane thermal conductivity of 1.96 ± 0.06 W m -1  K -1 . The high thermal conductivity of the copolymer film permits efficient Joule heat dissipation and, accordingly, excellent cyclic stability at elevated temperatures and high electric fields. The demonstration of the breakdown self-healing ability of the copolymer further suggests the promise of the ladderphane structures for high-energy-density polymer capacitors operating under extreme conditions., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Interest in making chiral polycyclic aromatic hydrocarbons (PAHs) or nanographenes (NGs) has greatly increased recently. To date, a majority of chiral nanocarbons have been designed based on helical chirality. Here, we describe a novel atropisomeric chiral oxa-NG 1 by the selective dimerization of naphthalene-containing, hexa- peri -hexabenzocoronene (HBC)-based PAH 6. The photophysical properties of the oxa-NG 1 and monomer 6 were investigated, including UV-vis absorption ( λ max = 358 nm for 1 and 6), fluorescence emission ( λ em = 475 nm for 1 and 6), fluorescence decay (15 vs. 16 ns), and fluorescence quantum yield, and it was found that the photophysical properties of the monomer are nearly maintained in the NG dimer due to its perpendicular conformation. Single-crystal X-ray diffraction analysis shows that both enantiomers cocrystallize in a single crystal, and the racemic mixture can be resolved by chiral high-performance liquid chromatography (HPLC). The circular dichroism (CD) spectra and circularly polarized luminescence (CPL) of the enantiomers of 1- S and 1- R were studied and the CD and CPL spectra exhibited opposite Cotton effects and fluorescence signals. Density functional theory (DFT) calculations and HPLC-based thermal isomerization results showed that the racemic barrier is as high as 35 kcal mol -1 , suggesting a rigid chiral nanographene structure. Meanwhile, in vitro studies indicated that oxa-NG 1 is an efficient photosensitizer for white-light-induced singlet oxygen generation., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

The development of cholestatic liver injury (CLI) involves inflammation, but the dominant pathway mediating the chemotaxis is not yet established. This work explored key signaling pathway mediating chemotaxis in CLI and the role of Kupffer cells in the inflammatory liver injury. Probe inhibitors T-5224 (100 mg/kg) for AP-1 and C188-9 (100 mg/kg) for STAT3 were used to validate key inflammatory pathways in alpha-naphthylisothiocyanate (ANIT, 100 mg/kg)-induced CLI. Two doses of GdCl 3 (10 mg/kg and 40 mg/kg) were used to delete Kupffer cells and explore their role in CLI. Serum and liver samples were collected for biochemical and mechanism analysis. The liver injury in ANIT-treated mice were significantly increased supported by biochemical and histopathological changes, and neutrophils gathering around the necrotic loci. Inhibitor treatments down-regulated liver injury biomarkers except the level of total bile acid. The chemokine Ccl2 increased by 170-fold and to a less degree Cxcl2 by 45-fold after the ANIT treatment. p-c-Jun and p-STAT3 were activated in the group A but inhibited by the inhibitors in western blot analysis. The immunofluorescence results showed AP-1 not STAT3 responded to inhibitors in ANIT-induced CLI. With or without GdCl 3 , there was no significant difference in liver injury among the CLI groups. In necrotic loci in CLI, CXCL2 colocalized with hepatocyte biomarker Albumin, not with the F4/80 in Kupffer cells. Conclusively, AP-1 played a more critical role in the inflammation cascade than STAT3 in ANIT-induced CLI. Hepatocytes, not the Kupffer cells released chemotactic factors mediating the chemotaxis in CLI., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The wetting property of a solid surface has been a hotspot for centuries, and many studies suggest that the hydrophobicity is highly related to the polar components. However, the underlying mechanism of polar moieties on the hydrophobicity remains unclear. Here, we tailor the surface polar moieties of epoxy resin (EP) by ozone modification and assess their wetting properties. Our results show that, for the modified EP with more (60.54%) polar moieties, the polar effect on hydrophobicity cannot be empirically observed. To reveal the underlying mechanism, the absorption parameters, including equilibrium distance, adsorption radius, and effective adsorption sites for water on EP before and after ozone treatment, are calculated on the basis of molecular simulations. After ozone modification, the equilibrium distance (from 1.95 to 1.70 Å), adsorption radius (from 3.80 to 4.50 Å), and effective adsorption sites (from 1 to 2) change slightly and the EP surface remains hydrophobic, although the polar groups significantly increase. Therefore, it is concluded that the wetting properties of solid surfaces are dominated by the equilibrium distance, adsorption radius, and effective adsorption sites for water on solids, and the nonlinear relationship between polar groups and hydrophilicity is clarified.

Objective: To evaluate the level of cardiometabolic index (CMI) to predict the risk of acute exacerbation in patients with stable chronic obstructive pulmonary disease (COPD), and to provide a basis for early identification and intervention of high-risk patients in clinical nursing work., Methods: Patients with stable chronic obstructive pulmonary disease who were admitted to the outpatient department of respiratory medicine in a tertiary hospital or followed up after discharge from January to December 2021 were retrospectively selected. CMI was measured and statistical analysis was performed to determine the optimal threshold for predicting acute exacerbation of chronic obstructive pulmonary disease., Results: A total of 63 patients with chronic obstructive pulmonary disease were enrolled. The median number of episodes in the previous year was 1.00; 44 patients had ≥1 acute exacerbation. The CMI was positively correlated with the frequency of acute exacerbations and the British Medical Research Council (mMRC) score in the previous year, and negatively correlated with the percentage of forced expiratory volume in 1 second to the predicted value (FEV1% PRED). The cut-off point of CMI for predicting acute exacerbations in stable chronic obstructive pulmonary disease patients was 2.05, with a sensitivity of 0.864% and specificity of 0.842%. It is a risk factor for acute exacerbation in COPD patients., Conclusion: CMI can be used as a biological index to predict acute exacerbation in stable COPD patients. Clinical nursing needs to evaluate patients' CMI and provide personalized nursing intervention for patients with CMI≥2.05., Competing Interests: The authors declare that there are no conflicts of interest., (Copyright © 2022 Ruqiao Luo et al.)

Gradually increasing power transmission voltage requires an improved high-voltage capability of polymeric insulating materials. Surface modification emerges as an easily accessible approach in enhancing breakdown and flashover performances due to the widely acknowledged modification of space-charge behaviors. However, as oxidation and fluorination essentially react within a limited depth of 2 μm underneath polymer surfaces, the nature of such bulk space-charge modulation remains a controversial issue, and further investigation is needed to realize enhancement of insulating performance. In this work, the surface oxidation-dependent space-charge accumulation in LDPE film was found to be dominated by an electrode/polymer interfacial barrier, but not by the generation of bulk charge traps. Through quantitative investigation of space-charge distributions along with induced electric field distortion, the functions of surface oxidation on the interfacial barrier of a typical dielectric polymer, LDPE, is discussed and linked to space-charge behaviors. As the mechanism of surface modification on space-charge behaviors is herein proposed, space-charge accumulation can be effectively modified by selecting an appropriate surface modification method, which consequentially benefits breakdown and flashover performances of polymeric insulating films for high-voltage applications.

Aryl azide and diaryl tetrazole are both photoactive molecules, which can form nitrene and nitrile imine intermediates respectively by photolysis. Depending on the new finding that the azide can suppress the photolysis of tetrazole in the azide-tetrazole conjugated system, we developed aryl azide-tetrazole probes for the photoactivatable fluorogenic azide alkyne click (PFAAC) reaction, in which the aryl azide-tetrazole probes were not phoroactivatable fluorogenic itself, but the triazole products after click reaction were prefluorophore that can be activated by light. Therefore, in PFAAC chemistry, the fluorescent probes can be activated by two orthogonal events: azide-alkyne click reaction and light, which leads to spatiotemporal resolution and high signal-to-noise ratio. This PFAAC process was proved in vitro by copper-catalyzed or strain-promoted azide-alkyne reactions and in live cells by spatiotemporally controlled organelle imaging. By incorporation a linker to the azide-tetrazole conjugate, this PFAAC chemistry could covalently label extra probes to the biomolecules and spatiotemporally detecting this process by photoinduced fluorescence., (© 2022 Wiley-VCH GmbH.)

Relaxor ferroelectric polymers display great potential in capacitor dielectric applications because of their excellent flexibility, light weight, and high dielectric constant. However, their electrical energy storage capacity is limited by their high conduction losses and low dielectric strength, which primarily originates from the impact-ionization-induced electronmultiplication, low mechanical modulus, and low thermal conductivity of the dielectric polymers. Here a matrix free strategy is developed to effectively suppress electron multiplication effects and to enhance mechanical modulus and thermal conductivity of a dielectric polymer, which involves the chemical adsorption of an electron barrier layer on boron nitride nanosheet surfaces by chemically adsorbing an amino-containing polymer. A dramatic decrease of leakage current (from 2.4 × 10 -6 to 1.1 × 10 -7 A cm -2 at 100 MV m -1 ) and a substantial increase of breakdown strength (from 340 to 742 MV m -1 ) were achieved in the nanocompostes, which result in a remarkable increase of discharge energy density (from 5.2 to 31.8 J cm -3 ). Moreover, the dielectric strength of the nanocomposites suffering an electrical breakdown could be restored to 88% of the original value. This study demonstrates a rational design for fabricating dielectric polymer nanocomposites with greatly enhanced electric energy storage capacity., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest., (Copyright © 2021 Science China Press. Published by Elsevier B.V. All rights reserved.)

In this paper, a fixed-time controller under the mechanism of event-trigger is designed for a class of nonlinear pure-feedback systems with non-differentiable non-affine functions. By properly modeling non-affine terms, the limitation of the partial derivatives of non-affine functions is eliminated. In our design process, we first develop a fixed-time adaptive controller using decoupling method. Then, a relative threshold event-trigger mechanism (ETM) is introduced in Section 3.1. The proposed controller can not only stabilize the system within a fixed-time, but also save communication resources more effectively. Lastly, the feasibility of the proposed control scheme is verified by two simulation examples., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 ISA. Published by Elsevier Ltd. All rights reserved.)

Despite the extensive research on nanocomposites, a fundamental theory on the interface region is still difficult to achieve. In the present paper, we chose epoxy resin and nano-SiO 2 , nano-SiC, nano-ZnO to prepare three kinds of nanocomposites. The dispersion characteristics at the terahertz range and dielectric permittivity at 1 Hz of epoxy resin-based nanocomposites were investigated. The reduction of the permittivity of nanocomposites at a slight filler concentration was absent at the terahertz range. The measurement results at 1 Hz show that the interaction between nano-SiO 2 , nano-SiC particles and epoxy resin was strong with the modification of the silane coupling agent. However, the modification of nano-ZnO particles was invalid. The Lorentz harmonic oscillator model was employed to fit the dispersion characteristics. The relevance between the damping constant and the dielectric permittivity at low frequency was established, indicating that the increase in the damping coefficient results from the restriction of the molecular chain motion by the interfacial region. The present results in this paper reveal a bright prospect of terahertz time-domain spectroscopy in establishing the theory of nanocomposite dielectric.

Surface charge density has been demonstrated to be significantly impacted by the dielectric properties of tribomaterials. However, the ambiguous physical mechanism of dielectric manipulated charge behavior still restricts the construction of high-performance tribomaterials. Here, using the atomic force microscopy and Kelvin probe force microscopy, an in situ method was conducted to investigate the contact electrification and charge dynamics on a typical tribomaterial (i.e., BaTiO 3 /PVDF-TrFE nanocomposite) at nanoscale. Combined with the characterization of triboelectric device at macroscale, it is found that the number of transferred electrons increases with contact force/area and tends to reach saturation under increased friction cycles. The incorporated high permittivity BaTiO 3 nanoparticles enhance the capacitance and electron trapping capability of the nanocomposites, efficiently inhibiting the lateral diffusion of electrons and improving the output performance of the triboelectric devices. Exponential decay of the surface potential is observed over monitoring time for all dielectric samples. At high BaTiO 3 loadings, more electrons can drift into the bulk and combine with the induced charges on the back electrode, forming a large leakage current and accordingly accelerating the electron dissipation. Hence, the charge trapping/storing and dissipating, as well as the charge attracting properties, should be comprehensively considered in the design of high-performance tribomaterials., Competing Interests: The authors declare that there is no conflict of interest regarding the publication of this article., (Copyright © 2022 Kunming Shi et al.)

Polymer dielectrics are highly desirable in capacitor applications due to their low cost, high stability, and reliability. However, there still remains a lack of feasible methods to prepare polymer dielectrics with high energy density and low dielectric loss, which severely hampers the development of compact and efficient power electronics. Here, an amphiphilic block copolymer, polythiourea-b-polydimethylsiloxane (PTU-b-PDMS), with an extraordinarily high energy density of 29.8 J cm -3 and a low loss is synthesized via polyaddition polymerization. This is highly relevant to the block molecule conformation in the interfacial region of the self-assembled PTU-b-PDMS. The block molecule in the interface adopts an extended conformation when the PTU forms nanodots, whereas the block molecule adopts a coiled conformation when the PTU forms nanostrands. The observation and characterization have proved that the coiled block molecule in the interfacial region can simultaneously induce extra strong charge trapping sites and dipolar polarization. It substantially improves the breakdown strength from 652 to 1166 MV m -1 , while maintaining a high dielectric constant of 5 and a low loss of <0.01. This work offers unprecedented structural insights into the conformation-induced interfacial effect and enables rational design of self-assembled copolymers to boost their dielectric properties and energy density., (© 2021 Wiley-VCH GmbH.)

Power equipment operates under high voltages, inducing space charge accumulation on the surface of key insulating structures, which increases the risk of discharge/breakdown and the possibility of maintenance workers experiencing electric shock accidents. Hence, a visualized non-equipment space charge detection method is of great demand in the power industry. Typical electrochromic phenomenon is based on redox of the material, triggered by a voltage smaller than 5 V with a continuous current in μA~mA level, which is not applicable to high electric fields above 10 6 V/m with pA~nA operation current in power equipment. Until now, no naked-eye observation technique has been realized for space charge detection to ensure the operation of power systems as well as the safety of maintenance workers. In this work, a viologen/poly(vinylidene fluoride-co-hexafluoropropylene)(P(VDF-HFP)) composite is investigated from gel to insulating bulk configurations to achieve high-voltage electrical-insulating electrochromism. The results show that viologen/P(VDF-HFP) composite bulk can withstand high electric fields at the 10 7 V/m level, and its electrochromism is triggered by space charges. This electrochromism phenomenon can be visually extended by increasing viologen content towards 5 wt.% and shows a positive response to voltage amplitude and application duration. As viologen/P(VDF-HFP) composite bulk exhibits a typical electrical insulating performance, it could be attached to the surface of insulating structures or clamped between metal and insulating materials as a space charge accumulation indicator in high-voltage power equipment.

Advanced ferroelectrics with a combination of large dielectric response and good temperature stability are crucial for many technologically important electronic devices and electrical storage/power equipment. However, the two key factors usually do not go hand in hand, and achieving high permittivity is normally at the expense of sacrificing temperature stability. This trade-off relation is eased but not fundamentally remedied using relaxor-type materials which are known to have a diffuse permittivity peak at their relaxor transition temperatures. Here, we report an anomalous trirelaxor phenomenon in a barium titanate system and show that it can lead to a giant dielectric permittivity (ε r ≈ 18 000) over a wide temperature range ( T span ≈ 34K), which successfully overcomes a long-standing permittivity-stability trade-off. Moreover, the enhancement in the dielectric properties also yields a desired temperature-insensitive electrocaloric performance for the trirelaxor ferroelectrics. Microstructure characterization and phase-field simulations reveal a mixture of tetragonal, orthorhombic, and rhombohedral polar nanoregions over a broad temperature window in trirelaxor ferroelectrics, which is responsible for this combination of giant dielectric permittivity and good temperature stability. This finding provides an effective approach in designing advanced ferroelectrics with high performance and thermal stability.

To date, breakdown voltage is an underlying risk to the epoxy-based electrical high voltage (HV) equipment. To improve the breakdown strength of epoxy resin and to explore the formation of charge traps, in this study, two types of polyhedral oligomeric silsesquioxane (POSS) fillers are doped into epoxy resin. The breakdown voltage test is performed to investigate the breakdown strength of neat epoxy and epoxy/POSS composites. Electron traps that play an important role in breakdown strength are characterized by thermally stimulated depolarized current (TSDC) measurement. A quantum chemical calculation tool identifies the source of traps. It is found that adding octa-glycidyl POSS (OG-POSS) to epoxy enhances the breakdown strength than that of neat epoxy and epoxycyclohexyl POSS (ECH-POSS) incorporated epoxy. Moreover, side groups of OG-POSS possess higher electron affinity ( E A ) and large electronegativity that introduces deep-level traps into epoxy resin and restrain the electron transport. In this work, the origin of traps has been investigated by the simulation method. It is revealed that the functional properties of POSS side group can tailor an extensive network of deep traps in the interfacial region with epoxy and enhance the breakdown strength of the epoxy/POSS nanocomposite.

Cholestatic liver fibrosis occurs in liver injuries accompanied by inflammation, which develops into cirrhosis if not effectively treated in early stage. The aim of the study is to explore the effect of fenofibrate on liver fibrosis in chronic cholestatic mice. In this study, wild-type (WT) and Pparα-null (KO) mice were dosed alpha-naphthylisothiocyanate (ANIT) diet to induce chronic cholestasis. Induced liver fibrosis was determined by pathological biomarkers. Then fenofibrate 25 mg/kg was orally administrated to mice twice/day for 14 days. Serum and liver samples were collected for analysis of biochemistry and fibrosis. In WT mice, cholestatic biomarkers were increased by 5-8-fold and the expression of tissue inhibitors of metalloproteinases 1 (TIMP-1), Monocyte chemoattractant protein 1 (MCP-1), Collagen protein I (Collagen I) was increased by more than 10-fold. Fenofibrate significantly downgraded the biochemical and fibrotic biomarkers. In Western blot analysis, levels of collagenI and alpha-smooth muscle actin (α-SMA) were strongly inhibited by fenofibrate. In KO mice, liver fibrosis was induced successfully, but no improvement after fenofibrate treatment was observed. These data showed low-dose fenofibrate reverses cholestatic liver fibrosis in WT mice but not in KO mice, suggesting the dependence of therapeutic action on peroxisome proliferator-activated receptor alpha (PPARα). The study offers an additional therapeutic strategy for cholestatic liver fibrosis in practice.

N-glycosylation is a fundamental post-translational protein modification in the endoplasmic reticulum of eukaryotic cells. The biosynthetic and catabolic flux of N-glycans in eukaryotic cells has long been analyzed by metabolic labeling using radiolabeled sugars. Here, we introduce a non-radiolabeling protocol for the isolation, structural determination, and quantification of N-glycan precursors, dolichol-linked oligosaccharides, and the related metabolites, including phosphorylated oligosaccharides and nucleotide sugars. Our protocol allows for capturing of the biosynthesis and degradation of N-glycan precursors at steady state. For complete details on the use and execution of this protocol, please refer to Harada et al. (2013), Harada et al. (2020), and Nakajima et al. (2013)., Competing Interests: The authors declare no competing interests., (© 2021 The Author(s).)

Insulation fails quickly under high-frequency AC high voltage, especially bipolar square-wave voltage with a high d V /d t . It is of great significance to study the failure mechanism of epoxy casting insulation under such kind of voltage. In this paper, pin-plane epoxy casting insulation samples with air gaps were prepared, and the relation between the electrical trees under the high frequency bipolar square-wave voltage and the air gap conditions and voltage frequencies (1~20 kHz) were studied. Results indicated that, with the presence of air gaps, the electrical trees were bush-type and had a relatively slow growth rate, which was different from the fast-growing branch-type trees in the samples without air gap. The electrical tree characteristics related with the size of air gap and voltage frequency were also studied. The electrical tree grew faster under higher voltage frequency or with a smaller air gap. Results proved that discharge introduced a lot of defects for the surface layer of the epoxy resin samples and hence induced the possibility of multi-directional expansion of electrical trees. In addition, the resulting heat accumulation and unique charge transport synergistically affected the electrical tree characteristics under the high frequency bipolar square-wave voltage.

The decrease in electrical properties caused by the toughening of polypropylene (PP) is a difficult problem for the modification of PP used for cable insulation. In this research, an isotactic PP, a cross-linked polyethylene (XLPE) and two impact PP copolymers (IPCs) with an ethylene-propylene rubber phase content of 15 and 30% were prepared to assess the possibility of IPCs to be used as cable insulating material. The tensile properties and breakdown strength were evaluated, meanwhile, the rubber phase content dependence of the crystalline structure, morphology and trap distribution were also investigated. Results show that IPCs with a 15% rubber phase content (IPC15) can achieve the simultaneous improvement of elongation at break and breakdown strength compared with isotactic PP, which can be attributed to the special crystalline structure. According to the results of differential scanning calorimetry (DSC) and FTIR, it is proposed that the lamella thickness of IPC15 is maximal and some ethylene segments exist in PP crystals of IPC15 as crystalline structure defects, which is responsible for this enhanced breakdown strength. The morphology results reveal that rubber microspheres are found to coexist with spherulites, which can promote the relative sliding among lamellas under external force and further results in the increase in the elongation at break.

Organic dielectric materials have been widely developed and investigated for energy storage capacitors. However, challenges remain in terms of the relatively low dielectric constant and energy density. Enhancing the dipolar polarization to increase the dielectric constant is considered to be an effective way to improve the energy density of polymer dielectrics. Herein, enlightened by the chain-packing structure that affects the dipolar relaxation behavior, a simple and low-cost approach is proposed to tailor the interdomain spacing in an alicyclic polythiourea (PTU) by changing quenching temperatures and further facilitate the dipolar polarization. It is found that the large interdomain spacing is beneficial to promote the localized motion of segmental chains in amorphous regions, but at the same time inevitably reduces the dipole density. Therefore, in order to achieve the highest dielectric constant in the PTU, there is an optimal value for the interdomain spacing. It is worth noting that the dielectric constant of PTU increases from 5.7 to 10, and thus the energy density increases by 53% to 16.3 J cm -3 . It proposes a simple and feasible strategy to further improve the energy density through optimizing the interdomain spacing toward high-energy-storable dielectric material., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In order to satisfy demands of cable insulation for nuclear power, a low-smoke, halogen-free flame retardant and better cryogenic property insulation was prepared. The effect of thermal-oxidative aging on the dielectric properties was researched in this paper. The changes of chemical structure and thermal-oxidative stability caused by aging were characterized by Fourier transform infrared spectroscopy and a differential scanning calorimeter. The results showed that, the oxidative-induced stability reduced as complex products accumulated during aging. The dielectric properties including polarity, conductivity and breakdown at different aging stages were measured. For comparison, tensile testing was performed. The parameters related to conductivity changed notably, and were comparable with the changes in mechanical properties.

Thermal ageing of cross-linked polyethylene (XLPE) cable insulation is an important issue threatening the safe operation of power cables. In this paper, thermal ageing of XLPE was carried out at 160 °C in air for 240 h. The influence of oxygen diffusion on thermal ageing of XLPE was investigated by Ultraviolet-visible spectrophotometer (UV-Vis), tensile testing, and Fourier transformed infrared spectroscopy (FTIR). It was observed that the degradation degree not only depended on ageing time but also on sample positions. The thermally aged samples were more oxidized in the surface region, presented a darker color, more carbon atoms appeared in the conjugate cluster, had smaller elongation at break and tensile strength, and a larger carbonyl index. As ageing time increased, the non-uniform oxidation of the XLPE samples became more prominent. The degree of non-uniform oxidation caused by oxygen diffusion was quantitatively studied by first order oxidation kinetic. The calculated results demonstrated that carbonyl index measured by FTIR was more sensitive to non-uniform oxidation with a shape parameter in the range of 1-2. The result shown in this paper is helpful for interpreting and predicting the non-uniform ageing behavior of high voltage XLPE cables.

The dielectric strength of cellulose-liquid composites is always about several times higher than that of the cellulose paper and insulating liquids. However, this experimental phenomenon has not yet been demonstrated theoretically. Herein, the spectra characterization, molecular simulation, and wave function analysis method provide a new insight that the role of nanoscale interfacial adsorption of cellulose-liquid is exclusive for composites affecting the charge separation and producing the deep-level traps to seriously hinder electromigration under an electric field, which is responsible for the difference in dielectric strength. Meanwhile, the π conjugation and σ-π hyperconjugation effects enhance the electrical stability of aromatic hydrocarbon insulating liquids. In conclusion, interfacial trap theory can be used to explain the correlation of dielectric strength between cellulose-liquid composites and cellulose paper or dielectric liquids. It can be expected that materials with high dielectric strength can be manufactured according to the fundamental study of interfacial trap theory.

Carcinoma-associated fibroblasts (CAFs), one of the most important components of a tumor microenvironment (TME), play a significant role in the complex tumorigenesis process. Herein, the evolution of CAFs in TME is elaborately investigated by surface-enhanced Raman spectroscopy (SERS), a molecular fingerprint technique. Two-dimensional (2D) nanocomposites consisting of gold nanoparticles and a supramolecular "PCsheet" self-assembled between 2D nanosheets and oxidized phosphatidylcholine (PC) are fabricated as SERS-active probes to specifically recognize the CD36 receptor on the cytomembrane of the fibroblasts, a reliable landmark of CAF development. The 2D SERS substrates can also illuminate the fingerprint information around the CD36 protein with high detection sensitivity, which helps elucidate the biochemical component transition in the protein mini-domain during carcinoma progression. Visualized data are then supplied by label-free SERS imaging to exploit the distribution of biomolecules on the plasma membrane. In addition, the repressed expression of CD36 in TME is detected in lung metastasis tumor-bearing mice. This study based on the 2D SERS technique opens up an alternative avenue for unveiling carcinoma-associated molecular events.

Epoxy resin-based nanocomposites have been widely researched for being potential insulating materials in high voltage power equipment. In this paper, nano-TiO 2 particles were chosen and surface-modified by a silane coupling agent containing an epoxy group. The effect of functionalized nano-TiO 2 doping on the physical properties of epoxy resin was studied. The results of differential scanning calorimetry show that T g increased significantly and can be increased by up to 35 °C. Therefore, it is believed that the suppression of molecular motion by the addition of nanofillers works effectively in the case of this functionalized nano-TiO 2 and a strong interaction between the epoxy resin and the nano-TiO 2 was formed after surface modification. Consequently, dynamic mechanical properties, thermal conductivity, electrical conductivity, and trap characteristics of epoxy resin are all adjusted after introducing functionalized nano-TiO 2 . All of these physical properties were analyzed from the perspective of suppression of molecular motion, and it is of significance to establish the theory of a nanocomposite dielectric. Besides, the results show that the epoxy/TiO 2 nanocomposite is expected to be applied in the insulation system of electrical equipment.

Dielectric breakdown is a significant property for the insulation system in high voltage power equipment. This paper is dedicated to the improvement of dielectric breakdown by surface-functionalized nanoparticles in low-density polyethylene (LDPE). Prior to the preparation of LDPE/TiO 2 nanocomposites, the nanoparticles were surface modified by the silane coupling followed by the chemical reaction process. Results of Fourier transform infrared spectroscopy (FTIR) indicated that some polar groups and chemical bonding were introduced on the surface of TiO 2 nanoparticles. A reduction of dielectric permittivity was observed at low nanoparticle loading (<2 wt%) samples, which responded to the restriction of the molecular chain in the interface region. High nanoparticle loadings (2 wt%, 5 wt%, 10 wt%) introduced an obvious relaxation polarization. The trap parameters detected by the thermally stimulated current (TSC) method indicated that the deep traps were introduced by small amounts of nanoparticles (≤2 wt%), while more shallow traps occurred in high loading (5 wt%, 10 wt%) samples. Meanwhile, the increase of breakdown strength at low loading samples were closely related to the deep traps, which was ascribed to the interface region by surface chemical modification.

Nano-dielectrics are sensitive to humidity and easily degraded in damp environment because of the high surface energy of nanoparticles. In order to study the effect of humidity on the dielectric properties of nano-dielectric, polypropylene (PP) was modified by polyolefin elastomer (POE) and nano-SiO 2 , and the samples with obvious filling concentration were pre-selected by breakdown strength for damp aging. The aging experiments were carried out in different relative humidity. The dielectric properties of new, hygroscopic saturation and samples after drying were measured and analyzed. It is found that the breakdown strength of hygroscopic saturation nano-dielectrics decreased obviously compared with new samples, and it was difficult to recover after drying. The damp degradation resulted in different changing trends of permittivity of PP and nano-dielectric, but there were relaxation loss peaks of water in both of them. The influence of damp degradation on the trap distribution was studied by thermally stimulated depolarization currents (TSDC), and it was found that the traps level introduced by water molecules was different in PP and nano-dielectrics. All experiment results showed that the performance of nano-dielectrics degraded obviously in humid environment, and it was difficult to recover even after complete drying because of the existence of bounded water molecules in nano-dielectrics.

Flashover is a crucial issue in both high-voltage engineering and surface physics. It not only challenges the existing theories about its dynamic evolution, but also inhibits the clean energy revolution by limiting the accessible voltage rating of power equipment. It is of significance to elucidate the microscopic process along the interface to improve the flashover performance. In the present study, the synergic effect of adsorbed gas and surface charging is investigated, which reveals a long ignored factor for determining the flashover voltage. Depending on the relative amount of adsorbed gas, the flashover voltage varies, which exhibit different behavior from the bulk breakdown of the same gas. The amount of N 2 gas adsorbed on epoxy resin (EP) surface is much larger than that on Al 2 O 3 ceramic surface, corresponding to the observed higher flashover voltage on EP. It is proposed that the adsorbed gas molecules not only modify the local surface charging state via their interaction with the trapped charges, but also capture free electrons due to the distortion of their electronic distribution. Both effects suppress the free path length of electrons in the gas-solid interface. This work explores another possibility to improve the surface flashover performance.

Temperature is one of the key factors affecting space charge accumulation in high voltage direct current (HVDC) cable insulation material. The influence of temperature on charge accumulation in low density polyethylene (LDPE) has been investigated with a combined thermally stimulated depolarization current (TSDC) method and pulsed electro-acoustic (PEA) method. The experimental results indicate that there exists a transition temperature region of charge accumulation around 50 °C. The total accumulated charges all firstly increase and then decrease with the increasing polarization temperature under three typical polarization electric fields, and they have more accumulated charges in LDPE around 50 °C. The phenomenon has a close link with the dynamic processes of charge trapping and de-trapping, which were verified by TSDC results. At room temperature, the trapped charges are difficult to release from the traps, and these homocharges near the cathode can depress the further injection of the charges. More charges can be injected from the electrodes with the increase of temperature, while the charge migration is relatively lower before 50 °C, leading to more accumulated charges. When the temperature exceeds around 50 °C, the molecular movement is accelerated which can enhance the hopping probability of charges between the adjacent traps, resulting in few accumulated charges.

Polar groups and the charge-transport capability play significant roles in the dielectric properties of organic polymers, and thus influence the electric energy density upon application as a capacitor material. Here, the dielectric properties and electric conductivity of a series of polymers containing 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radicals are investigated. The neat radical polymer poly(TEMPO methacrylate) (PTMA) has a high dielectric constant but poor breakdown strength. Poly(methyl methacrylate) (PMMA) is introduced as an insulating polymer with high resistivity on breakdown, along with molecular design of PTMA. Copolymers of TEMPO methacrylate and methyl methacrylate, P(TMA-r-MMA), exhibit high breakdown strengths but low dielectric constants. PMMA blended with TEMPO exhibits the highest electric energy density of 7.4 J cm -3 (that of PTMA is 0.48 J cm -3 as a control), with both a high dielectric constant (≈6.8) and a high breakdown strength (≈500 MV m -1 ). It benefits from long-range but not bulk charge transport in the blends, which is different from the bulk charge transport in PTMA and the short-range charge transport in P(TMA-r-MMA). These results indicate that the TEMPO moiety located in the high breakdown matrix leads to a high energy-storage density in the capacitor., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Dielectric energy storage capacitors have advantages such as ultra-high power density, extremely fast charge and discharge speed, long service lifespan and are significant for pulsed power system, smart power grid, and power electronics. Polypropylene (PP) is one of the most widely used dielectric materials for dielectric energy storage capacitors. It is of interest to investigate how to improve its electrical breakdown strength by nanodoping and the influencing mechanism of nanodoping on the electrical breakdown properties of polymer nanocomposites. PP/Al₂O₃ nanocomposite dielectric materials with various weight fraction of nanoparticles are fabricated by melt-blending and hot-pressing methods. Thermally stimulated current, surface potential decay, and dc electrical breakdown experiments show that deep trap properties and associated molecular chain motion are changed by incorporating nanofillers into polymer matrix, resulting in the variations in conductivity and dc electrical breakdown field of nanocomposite dielectrics. Then, a charge transport and molecular displacement modulated electrical breakdown model is utilized to simulate the dc electrical breakdown behavior. It is found that isolated interfacial regions formed in nanocomposite dielectrics at relatively low loadings reduce the effective carrier mobility and strengthen the interaction between molecular chains, hindering the transport of charges and the displacement of molecular chains with occupied deep traps. Accordingly, the electrical breakdown strength is enhanced at relatively low loadings. Interfacial regions may overlap in nanocomposite dielectrics at relatively high loadings so that the effective carrier mobility decreases and the interaction between molecular chains may be weakened. Consequently, the molecular motion is accelerated by electric force, leading to the decrease in electrical breakdown strength. The experiments and simulations reveals that the influence of nanodoping on dc electrical breakdown properties may origin from the changes in the charge transport and molecular displacement characteristics caused by interfacial regions in nanocomposite dielectrics.

Polyimide has excellent electrical, thermal, and mechanical properties and is widely used as a dielectric material in electrical equipment and electronic devices. However, the influencing mechanism of sample thickness on electrical breakdown of polyimide has not been very clear until now. The direct current (DC) electrical breakdown properties of polyimide as a function of thickness were investigated by experiments and simulations of space charge modulated electrical breakdown (SCEB) model and charge transport and molecular displacement modulated (CTMD) model. The experimental results show that the electrical breakdown field decreases with an increase in the sample thickness in the form of an inverse power function, and the inverse power index is 0.324. Trap properties and carrier mobility were also measured for the simulations. Both the simulation results obtained by the SCEB model and the CTMD model have the inverse power forms of breakdown field as a function of thickness with the power indexes of 0.030 and 0.339. The outputs of the CTMD model were closer to the experiments. This indicates that the displacement of a molecular chain with occupied deep traps enlarging the free volume might be a main factor causing the DC electrical breakdown field of polyimide varying with sample thickness.

Polypropylene (PP) contains promising application prospects in thermoplastic cables for high voltage direct current (HVDC) power transmission because of its outstanding thermal and dielectric properties. However, the problem of poor toughness and space charge has restricted the application of pure PP in HVDC cables. In this paper, polyolefin elastomer (POE) and nano-silica were blended thoroughly and added into a PP mixture by a melting method. Scanning electron microscopy (SEM) was employed to observe the dispersion of POE and nanoparticles. Thermal properties were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Mechanical properties were evaluated by tensile tests. The elastomeric properties of composites were improved as the dispersed POE could transfer and homogenize external mechanical forces. DC breakdown results showed that the fail strength of composite with 10 phr POE and 1 phr nano-silica was obviously enhanced. The pulsed electro-acoustic (PEA) results showed that the injection and accumulation of space charge was increased by the introduction of POE, while it was restrained by the collective effect caused by nano-silica filling. X-ray diffraction (XRD) spectrograms showed that secondary ordered structures existed in the composites of PP, POE, and nano-silica, and that the ordered structure around the nanoparticles contributed to the enhancement of breakdown strength. The mechanical and dielectric properties were modified synergistically, which made the modified PP a propitious insulation material for HVDC cables., Competing Interests: The authors declare no conflict of interest.

Previous studies have shown that nanoparticles can induce autophagy, and the main approach for investigating autophagy induced by nanoparticles is via traditional methods such as TEM and biochemical assay. These methods measurements suffer from the disadvantages of complicated experimental processes, cell destruction, as well as lack of characterization of individual stages of the autophagy pathway. Surface-enhanced Raman scattering (SERS) has been extensively used in biological applications. With the combination of SERS and chemometric methods, such as principal component analysis-linear discriminant analysis (PCA-LDA), identification and distribution mapping of endosomes and lysosomes in the endocytosis of Au nanoparticles has been achieved by segregating the spectra from complex SERS data sets in the previous study. In this study, silver@gold core-shell nanoparticles (Ag@Au NPs) were synthesized by reduction of gold ions on the surface of the silver nanoparticles, and the autophagy induced by Ag@Au NPs was studied with Ag@Au NPs serving both as an autophagy inducer and as a high-performance SERS substrate. Pro-survival autophagy induced by Ag@Au NPs was proved by the western blot assay, flow cytometry and fluorescent staining. Furthermore, the autophagy pathway in Ag@Au NPs-treated cells was first elucidated by SERS combined with a modified reference-based PCA-LDA methodology. This study provides a feasible way of using SERS to elucidate the autophagy pathway induced by nanoparticles.