Controllable 3D Flower-Like Ag-CF Electrodes as Flexible Marine Electric Field Sensors with High Stability.

Construction of three-dimensional (3D) flower-like nanostructures with controlled morphologies has emerged as an attractive tool by scientists in the marine electric field sensor research field due to their peculiar structural features. Herein, novel 3D flower-like Ag-CF capacitive composite electrodes have been created by an eco-friendly water-bath strategy via AgNO3 as a sliver source and subsequently compounded with carbon fibers (CFs) pretreated by thermal oxidation. A series of electrode samples with various morphologies obtained by modulating different reaction times and temperatures bring about the dominant formation mechanism of these nanostructures and the influence behavior on the CF electrode in detail. Especially, the 3D flower-like Ag-CF electrode shows a large surface area acquired under the conditions of 80 °C and 15 min, which can provide more electroactive sites in electrochemical analysis and exhibit a maximum areal specific capacitance of 619.75 mF·cm-2 at a scanning speed of 10 mV·s-1. This is mainly due to the synergistic behavior of the unique 3D flower-like morphology and the large specific surface area of CFs. Furthermore, a cylinder-shaped Ag-CF sensor is designed, which delivers a superior potential difference of 33.08 µV, a potential difference drift of 18.62 µV/24 h for 30 days, and a self-noise of 0.92 nV/rt (Hz)@1 Hz. In this work, the intriguing synthesis strategy can be a promising facile approach to manufacture the controllable 3D flower-like Ag-CF electrode for electric field sensor applications.

Integrated Ultrafine Co0.85 Se in Carbon Nanofibers: An Efficient and Robust Bifunctional Catalyst for Oxygen Electrocatalysis.

Transition-metal selenides are emerging as alternative bifunctional catalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR); however, their activity and stability are still less than desirable. Herein, ultrafine Co0.85 Se nanoparticles encapsulated into carbon nanofibers (CNFs), Co0.85 Se@CNFs, is reported as an integrated bifunctional catalyst for OER and ORR. This catalyst exhibits a low OER potential of 1.58 V vs. reversible hydrogen electrode (RHE) (EJ=10, OER ) to achieve a current density (J) of 10 mA cm-2 and a high ORR potential of 0.84 V vs. RHE (EJ=-1, ORR ) to reach -1 mA cm-2 . Thus, the potential between EJ=10, OER and EJ=-1, ORR is only 0.74 V, indicating considerable bifunctional activity. The excellent bifunctionality can be attributed to high electronic conduction, abundant electrochemically active sites, and the synergistic effect of Co0.85 Se and CNFs. Furthermore, this Co0.85 Se@CNFs catalyst displays good cycling stability for both OER and ORR. This study paves a new way for the rational design of hybrid catalysts composed of transition-metal selenides and carbon materials for efficiently catalyzing OER and ORR.

Nickel-Based Bicarbonates as Bifunctional Catalysts for Oxygen Evolution and Reduction Reaction in Alkaline Media.

Oxygen electrocatalysis, including the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), is one of the most important electrochemical processes for sustainable energy conversion and storage technologies. Herein, nickel-based bicarbonates are, for the first time, developed as catalysts for oxygen electrocatalysis, and demonstrate superior electrocatalytic performance in alkaline media. Iron doping can significantly tune the real valence of nickel ions, and consequently tailor the electrocatalytic ability of bicarbonates. Among the nickel-based bicarbonates, Ni0.9 Fe0.1 (HCO3 )2 exhibits the highest bifunctional catalytic activity, with a potential difference of 0.86 V between the OER potential at a current density of 10 mA cm-2 and the ORR potential at a current density of -1 mA cm-2 , which outperforms most of the reported precious-metal-free catalysts. The present work provides new insights into exploring efficient catalysts for oxygen electrocatalysis, and it suggests that, in addition to the extensively studied transition metal hydroxides and oxides, bicarbonates and carbonates also show great potential as precious metal-free catalysts.

Endothelial tubes form from intracellular vacuoles in implanted biomaterial in vivo of rat.

When the porous biomaterials are used to implant in vivo of animal for repairing wound, the angiogenesis in microenvironment of porous biomaterial is a key process in order to achieve the goal of treatment. While clarifying the process of vascularization and its mechanism is of great significance for design and development of medical biomaterials. In this area, it is noted that the endothelial tubes of new capillaries are formed by intracellular vacuoles, which has been proved in vitro model of angiogenesis. However, there is still no conclusive evidence in vivo model for mammals. By experimental tracking and observation of angiogenesis in the biomaterials implanted in rats, the angiogenesis process and the characteristics were explored. This study focused on the behavior of endothelial cell (EC)s and the capillary lumen formatting from EC cord in sprouting. Through marking and observing the ECs, the experimental evidences of angiogenesis after implanted materials into rats were obtained, which including various stages, such as rapidly proliferating of ECs, assembling of ECs to build up cell cord and vacuoles formation in ECs. An important mechanism of lumen formation for mammal in vivo was proved, which complemented the experimental results of the assembly of endothelial tubes in vivo through the formation and fusion of vacuoles for transgenic zebrafish. Our results provide support for the model of lumen formation of new capillary in mammal.

The association of the hepatitis B virus infection and diffuse large B-cell lymphoma.

OBJECTIVES: To investigate the basic characteristics of patients with diffuse large B-cell lymphoma (DLBCL) and whether hepatitis B surface antigen positive (HBsAg [+]) affects the survival of patients with DLBCL. METHODS: The study was carried out at Affiliated Hospital of Hebei University, Baoding, China, including 602 DLBCL cases from January 2011 to December 2021. We analyzed patients' general clinical data and applied multivariate and univariate Cox analyses to assess the factors influencing their survival times. RESULTS: The HBsAg(+) and HBsAg(-) groups comprised 154 (25.6%) and 448 (74.4%) of the 602 cases, respectively. HBsAg(+) cases tended to be later-stage (III-IV) with higher international prognostic index (IPI) points (3-5) and a greater tendency toward B symptoms, impaired liver function, and recurrence than HBsAg(-) cases (all p<0.05). After follow-up, 194 (32.2%) patients died. The median overall survival (OS) and 5-year OS rates in the HBsAg(+) and HBsAg(-) groups were 16.5 months (42%) and 35 months (63%), respectively. Cox analyses indicated that HBsAg(+) affected the prognosis of DLBCL cases (HR=1.46, 95%CI=1.07-1.99, p=0.017). CONCLUSION: The HBsAg(+) seems to be an independent hazard factor for the worse prognosis of DLBCL patients; hence, a focus on these patients in clinic is required.

Modulators for palmitoylation of proteins and small molecules.

As an essential form of lipid modification for maintaining vital cellular functions, palmitoylation plays an important role in in the regulation of various physiological processes, serving as a promising therapeutic target for diseases like cancer and neurological disorders. Ongoing research has revealed that palmitoylation can be categorized into three distinct types: N-palmitoylation, O-palmitoylation and S-palmitoylation. Herein this paper provides an overview of the regulatory enzymes involved in palmitoylation, including palmitoyltransferases and depalmitoylases, and discusses the currently available broad-spectrum and selective inhibitors for these enzymes.

Transcranial Direct Current Stimulation for Knee Osteoarthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

OBJECTIVE: The effects of transcranial direct current stimulation (tDCS) in the treatment of knee osteoarthritis (KOA) is still unclear. The objective is to evaluate the efficacy and safety of tDCS in improving symptoms in patients with KOA. METHODS: The following electronic databases were searched for eligible randomized controlled trials (RCTs): PubMed, Embase, Web of Science, and the Cochrane Library. The search was performed from the inception dates to April 30, 2023. Data extraction and quality assessment were performed by two independent reviewers. Standard mean differences (SMDs) with 95% confidence intervals (95% CIs) for pooled data were calculated. A random-effects model was used for the data analyses. The primary outcomes were pain and physical function. Secondary outcomes included stiffness, mobility performance, quality of life, pressure pain tolerance, and plasma levels of brain-derived neurotrophic factor (BDNF). RESULTS: This meta-analysis included 13 RCTs. tDCS was significantly associated with pain decrease compared with sham tDCS (SMD = -0.62, 95% CI -0.87 to -0.37, P < 0.00001). When comparing tDCS plus other non-tDCS with sham tDCS plus other non-tDCS, there was no longer a significant association with pain decrease (SMD = -0.45, 95% CI -1.08 to 0.17, P = 0.16). The changes in physical function were not significantly different between the tDCS and sham tDCS groups (SMD = -0.09, 95% CI -0.56 to 0.38, P = 0.71). When comparing tDCS plus other non-tDCS with sham tDCS plus other non-tDCS, there was still no significant association with improvement in physical function (SMD = -0.66, 95% CI -1.63 to 0.30, P = 0.18). There was no significant difference with improvement in stiffness (SMD = -0.21, 95% CI -0.77 to 0.34, P = 0.45), mobility performance (SMD = 4.58, 95% CI -9.21 to 18.37, P = 0.51), quality of life (SMD = -7.01, 95% CI -22.61 to 8.59, P = 0.38), and pressure pain tolerance (SMD = 0.30, 95% CI -0.09 to 0.69, P = 0.13). There was a statistically significant reduction in plasma levels of BDNF (SMD = -13.57, 95% CI -24.23 to -2.92, P = 0.01). CONCLUSION: In conclusion, tDCS could significantly alleviate pain, but it might have no efficacy in physical function, stiffness, mobility performance, quality of life, and pressure pain tolerance among patients with KOA.

Role of vascular endothelial progenitor cells in construction of new vascular loop.

Since bone marrow-derived endothelial progenitor cells (EPCs) have been detected in adult peripheral blood, the mode of vasculogenesis in the adult tissue has caught attention in field of vascularization research. To confirm the role of EPCs in construction of new vascular loop, we took the biomaterial scaffold implanted into adult rat as an experimental model to observe and examine the actions of the EPCs in neovascularization of the material by immunohistochemistry and transmission electron microscopy. Additionally, by establishing a chemotactic migration model for vascular endothelial cells (ECs) and EPCs, the migrations of ECs and EPCs were explored in simulations. The results of 20,000 simulations showed that the number of the vascular loops assisted by the EPCs was 2-5 times that of the vascular sprouts being naturally joined. Based on the results of experiments and simulations, we conclude that the EPCs are able to assist the angiogenic sprouts in joining under the condition of plenty of the EPCs being mobilized, which aggregate at sites close to sprout tips, forming a cell cord and differentiating to ECs in situ, and become vessel segments between neighboring sprouts. This suggests that there is a difference between the adult and embryo in the manner of vasculogenesis and that a small number of EPCs can play an important role to make the new blood vessels achieve rapid functionalization.

Characterization of Small Molecule-Protein Interactions Using SPR Method.

Surface plasmon resonance (SPR) is an optical phenomenon being used to monitor molecular binding events. With the advantages of being label-free, real-time, and sensitive, SPR assays have become one of the most commonly used techniques to measure binding kinetics, affinity, specificity, and concentration of molecular interactions. In an SPR experiment to measure small molecule-protein interactions, the protein is immobilized on the biosensor surface, while the small molecule flows through the surface of the sensor chip. The interactions between the small molecules and proteins are monitored by subsequent changes in the refractive index and quantified with resonance units. In this chapter, we have utilized an SPR assay to study the interaction of flavonoids and the glucose-regulated protein 78. Assay steps are detailed for immobilization optimization, SPR instrument setup, operation, sample injection, and affinity data analysis.

Preparation and performance study of multichannel PLA artificial nerve conduits.

Compared with single-channel nerve conduits, multichannel artificial nerve conduits are more beneficial for repairing damaged peripheral nerves of long-distance nerve defects. Multichannel nerve conduits can be fabricated by the mold method and the electrospinning method but with disadvantages such as low strength and large differences in batches, while the braiding method can solve this problem. In this study, polylactic acid yarns were used as the braiding yarn, and the number of spindles during braiding was varied to achieve 4, 5, 6, 7 and 8 multichannel artificial nerve conduits. A mathematical model of the number of braiding yarn spindles required to meet certain size specification parameters of the multichannel conduit was established. The cross-sectional morphology and mechanical properties of the conduits were characterized by scanning electron microscopy observation and mechanical testing; the results showed that the multichannel structure was well constructed; the tensile strength of the multichannel conduit was more than 30 times that of the rabbit tibial nerve. The biocompatibility of the conduit was tested; thein vitrocell culture results proved that the braided multichannel nerve conduits were nontoxic to Schwann cells, and the cell adhesion and proliferation were optimal in the 4-channel conduit among the multichannel conduits, which was close to the single-channel conduit.

Effect of degumming degree on the structure and tensile properties of RSF/RSS composite films prepared by one-step extraction.

Regenerated silk fibroin (RSF) and regenerated sericin (RSS) have attracted much attention for tissue engineering due to excellent biocompatibility and controllable degradation. However, pure RSF films prepared by existing methods are brittle, which limits applications in the field of high-strength and/or flexible tissues (e.g. cornea, periosteum and dura). A series of RSF/RSS composite films were developed from solutions prepared by dissolving silks with different degumming rates. The molecular conformation, crystalline structure and tensile properties of the films and the effect of sericin content on the structure and properties were investigated. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction results revealed more ß-sheets in films prepared by boiling water degumming than in Na2CO3-degummed RSFC film. Analysis of mechanical properties showed that the breaking strength (3.56 MPa) and elongation (50.51%) of boiling water-degummed RSF/RSS film were significantly increased compared with RSFC film (2.60 MPa and 32.31%), and the flexibility of films could be further improved by appropriately reducing the degumming rate.

Copper-doped perylene diimide supramolecules combined with TiO2 for efficient photoactivity.

Designing organic-inorganic hybrid semiconductors is an effective strategy for improving the performance of the photocatalyst under visible light irradiation. In this experiment, we firstly introduced Cu into perylenediimide supramolecules (PDIsm) to prepare the novel Cu-dopped PDIsm (CuPDIsm) with one-dimensional structure and then incorporated CuPDIsm with TiO2 to improve the photocatalytic performance. The introduction of Cu in PDIsm increases both the visible light adsorption and specific surface areas. Cu2+ coordination link between adjacent perylenediimide (PDI) moleculars and H-type π-π stacking of the aromatic core greatly accelerate the electron transfer in CuPDIsm system. Moreover, the photo-induced electrons generated by CuPDIsm migrate to TiO2 nanoparticles through hydrogen bond and electronic coupling at the TiO2/CuPDIsm heterojunction, which further accelerates the electron transfer and the separation efficiency of the charge carriers. So, the TiO2/CuPDIsm composites exhibit excellent photodegradation activity under visible light irradiation, reaching the maximum values of 89.87 and 97.26% toward tetracycline and methylene blue, respectively. This study provides new prospects for the development of metal-dopping organic systems and the construction of inorganic-organic heterojunctions, which can effectively enhance the electron transfer and improve the photocatalytic performance.

Self-Powered Infrared Photodetectors with Ultra-High Speed and Detectivity Based on Amorphous Cu-Based MOF Films.

Amorphous metal-organic frameworks (aMOFs) start to challenge their crystalline equivalents due to their unique advantages, like lack of grain boundaries, isotropy, flexibility, numerous defects-induced active sites, etc. However, aMOFs are typically synthesized under rigorous conditions, and their properties and applications need to be further explored. In this work, highly transparent p-type amorphous Cu-HHTP films consisting of Cu2+ and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) were synthesized using a simple electrostatic spinning method and identified as p-a-Cu-HHTP. Besides, a p-a-Cu-HHTP/n-Si infrared photodetector (PD) operating on a self-powered basis with ultra-high speed (response time of 40 µs) and detectivity (1.2 × 1012 Jones) has been developed, with a response time and detectivity that are record values for a MOF-based photodetector. In particular, the p-a-Cu-HHTP/n-Si PD can withstand high temperatures up to 180 °C without property change. Moreover, a flexible metal-semiconductor-metal photodetector based on p-a-Cu-HHTP is constructed, which shows excellent mechanical stability and photoresponse that remain unchanged after bending 120 times, implying its suitability for wearable optoelectronics. The new method to fabricate aMOFs, the unique p-a-Cu-HHTP, and its PDs initiated in this work opens up a new avenue in organic-inorganic hybrid optoelectronics.

Corrigendum: Construction of a three-level enteral nutrition nursing system under the "Internet + medical" mode and an evaluation of its effect in clinical application.

[This corrects the article DOI: 10.3389/fpubh.2022.976276.].

Construction of a three-level enteral nutrition nursing system under the "Internet + medical" mode and an evaluation of its effect in clinical application.

Objective: This study aimed to explore the construction of a three-level enteral nutrition nursing system under the "Internet + medical" mode and the clinical application effect. Methods: A total of 40 nurses from four primary and secondary hospitals in Jiangxi Province and 100 patients treated with enteral nutrition between January 2020 and December 2021 were enrolled in this study. Patients in the control group received routine enteral nutrition nursing. In the study group, a three-level enteral nutrition nursing system was applied under the "Internet + medical" mode to train and guide the implementation of clinical enteral nutrition. The changes in nurses' cognition and behavior in enteral nutrition safety nursing, comprehensive core competence before and after training, and the effect of enteral nutrition nursing were compared between the two groups. Results: After 3 months of training, nurses' cognition and behavior scores in enteral nutrition safety nursing were higher than those before training (t = 11.780, P < 0.05), and nurses' core competence scores were higher than before training (P < 0.05). After 1 week of nursing, the nutritional risk screening 2002 (NRS2002) score decreased, and the levels of albumin and hemoglobin increased in both groups (P < 0.05). However, after 1 week of nursing, the NRS2002 score of the study group (2.89 ± 0.75) was lower than that of the control group (3.25 ± 0.82), and the levels of albumin (39.89 ± 3.21) and hemoglobin (119.57 ± 8.78) were higher in the study group than in the control group (albumin 36.25 ± 3.45, hemoglobin 113.66 ± 9.55) (P < 0.05). Conclusion: Three-level enteral nutrition nursing linkage assisted by the "Internet + medical" mode can improve the cognition and behavior of medical staff in enteral nutrition safety nursing, as well as the comprehensive core competence of nurses, achieving good clinical effects.

Acupuncture for low back and/or pelvic pain during pregnancy: a systematic review and meta-analysis of randomised controlled trials.

OBJECTIVE: Acupuncture is emerging as a potential therapy for relieving pain, but the effectiveness of acupuncture for relieving low back and/or pelvic pain (LBPP) during the pregnancy remains controversial. This meta-analysis aims to investigate the effects of acupuncture on pain, functional status and quality of life for women with LBPP pain during the pregnancy. DESIGN: Systematic review and meta-analysis. DATA SOURCES: The PubMed, EMBASE databases, Web of Science and Cochrane Library were searched for relevant randomised controlled trials (RCTs) from inception to 15 January 2022. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: RCTs evaluating the effects of acupuncture on LBPP during the pregnancy were included. DATA EXTRACTION AND SYNTHESIS: The data extraction and study quality assessment were independently performed by three reviewers. The mean differences (MDs) with 95% CIs for pooled data were calculated. We assessed the confidence in the evidence using the Grading of Recommendations Assessment, Development and Evaluation framework. MAIN OUTCOMES AND MEASURES: The primary outcomes were pain, functional status and quality of life. The secondary outcomes were overall effects (a questionnaire at a post-treatment visit within a week after the last treatment to determine the number of people who received good or excellent help), analgesic consumption, Apgar scores >7 at 5 min, adverse events, gestational age at birth, induction of labour and mode of birth. RESULTS: This meta-analysis included 10 studies, reporting on a total of 1040 women. Overall, acupuncture significantly relieved pain during pregnancy (MD=1.70, 95% CI: (0.95 to 2.45), p<0.00001, I2=90%) and improved functional status (MD=12.44, 95% CI: (3.32 to 21.55), p=0.007, I2=94%) and quality of life (MD=-8.89, 95% CI: (-11.90 to -5.88), p<0.00001, I2 = 57%). There was a significant difference for overall effects (OR=0.13, 95% CI: (0.07 to 0.23), p<0.00001, I2 = 7%). However, there was no significant difference for analgesic consumption during the study period (OR=2.49, 95% CI: (0.08 to 80.25), p=0.61, I2=61%) and Apgar scores of newborns (OR=1.02, 95% CI: (0.37 to 2.83), p=0.97, I2 = 0%). Preterm birth from acupuncture during he study period was reported in two studies. Although preterm contractions were reported in two studies, all infants were in good health at birth. In terms of gestational age at birth, induction of labour and mode of birth, only one study reported the gestational age at birth (mean gestation 40 weeks). Thus, prospective randomised clinical studies or clinical follow-up studies were hence desirable to further evaluate these outcomes. CONCLUSIONS: Acupuncture significantly improved pain, functional status and quality of life in women with LBPP during the pregnancy. Additionally, acupuncture had no observable severe adverse influences on the newborns. More large-scale and well-designed RCTs are still needed to further confirm these results. PROSPERO REGISTRATION NUMBER: CRD42021241771.

Solution-processed transparent p-type orthorhombic K doped SnO films and their application in a phototransistor.

The exploitation of p-type oxide semiconductors with excellent optoelectrical properties as well as a simple preparation process is still challenging owing to the difficulty in producing hole carriers which results from strong hole localization in p-type oxide semiconductors. In this work, we succeeded in using ethylene glycol as a reductant to prepare orthorhombic structure SnO films using a sol-gel method and through K doping the optical and electrical properties of the films were improved. When the orthorhombic K doped SnO (K-SnO) films were applied in a phototransistor, it presented ultra-broadband photosensing from the ultraviolet to infrared region (300-1000 nm), demonstrating a photoresponsivity of 349 A W-1 and a detectivity of 5.45 × 1012 Jones at 900 nm under a light intensity of 0.00471 mW cm-2. In particular, infrared photosensing was for the first time reported in the SnO based phototransistors. This work not only provides a simple method to fabricate high-performance and low-cost p-type K-SnO films and phototransistors, but may also suggest a new way to improve the p-type characteristics of other oxide semiconductors and devices.

Optimizing nanostructures to achieve enhanced breakdown strength and improved energy storage performances in dipolar polymers.

Polymer dielectrics have attracted ever-increasing attention for electrical energy storage applications in recent years. Typically, polymer-based nanocomposite films are adopted to obtain polymer dielectrics with high energy density but sometime suffer from the inhomogeneous distribution of fillers. In this work, enhanced breakdown strength, suppressed dielectric loss and improved energy storage performances of PVDF film are concurrently achieved via the regulation of the sub-nano free volume, without introduction of any kinds of fillers and also minimizing the uneven distribution of the local electric field. The most improved breakdown strength is up to 488 MV m-1, with an enhancement of 60% compared with that of pristine PVDF, which enables the irradiated PVDF film to exhibit an improved polarization strength and charged energy density, giving rise to a maximum polarization strength of 3.55 µC cm-2 and a charged energy density of 9.75 J cm-3. More importantly, the irradiated PVDF film exhibits a superior discharged energy density of 7.91 J cm-3 which is 261% that of the pristine PVDF film, while maintaining the charge-discharge efficiency above 80%. In addition, the alteration of experimental breakdown strength with the increase of irradiation dose is found to be inversely correlated with the size variation of free volume holes, and the theoretical simulation of local electric field distribution further proves that the breakdown strength enhancement originates from the size shrinkage of free volume holes. The adjustment of free volume provides a potentially effective way to regulate the dielectric properties and energy storage performances of dipolar polymers.

Matrix Regeneration Ability In Situ Induced by a Silk Fibroin Small-Caliber Artificial Blood Vessel In Vivo.

The success of a small-caliber artificial vascular graft in the host in order to obtain functional tissue regeneration and remodeling remains a great challenge in clinical application. In our previous work, a silk-based, small-caliber tubular scaffold (SFTS) showed excellent mechanical properties, long-term patency and rapid endothelialization capabilities. On this basis, the aim of the present study was to evaluate the vascular reconstruction process after implantation to replace the common carotid artery in rabbits. The new tissue on both sides of the SFTSs at 1 month was clearly observed. Inside the SFTSs, the extracellular matrix (ECM) was deposited on the pore wall at 1 month and continued to increase during the follow-up period. The self-assembled collagen fibers and elastic fibers were clearly visible in a circumferential arrangement at 6 months and were similar to autologous blood vessels. The positive expression rate of Lysyl oxidase-1 (LOXL-1) was positively correlated with the formation and maturity of collagen fibers and elastic fibers. In summary, the findings of the tissue regeneration processes indicated that the bionic SFTSs induced in situ angiogenesis in defects.

Free volume dependence of the dielectric constant of poly(vinylidene fluoride) nanocomposite films.

The free volume effects on the dielectric properties of the polymer are ambiguous, and the quantitative effect of free volume on the dielectric properties has rarely been systematically studied, especially in the high-elastic state dipolar (HESD) polymer. In this work, the free volume of dipolar poly(vinylidene fluoride) (PVDF) is regulated by the addition of Al2O3, which greatly increase the size of free volume holes. Then the effect of free volume on the dielectric properties of PVDF/Al2O3 composites is discussed. The greatly enlarged size of free volume holes is believed to potentially generate disparate effects on dielectric constant under different frequencies in such kinds of HESD polymer-based composites, bringing about more remarkable frequency dependence of the dielectric constant. The influence of atomic-scale microstructure based on free volume further clarifies the free volume effects on the dielectric properties and provides valuable insights for the research of dielectric behaviour of polymer composites, which is constructive to design novel dielectric materials and further optimize the dielectric properties of dipolar dielectric polymer composites.