Overexpression of the PtrNF-YA6 gene inhibits secondary cell wall thickening in poplar.

The NF-Y gene family in plants plays a crucial role in numerous biological processes, encompassing hormone response, stress response, as well as growth and development. In this study, we first used bioinformatics techniques to identify members of the NF-YA family that may function in wood formation. We then used molecular biology techniques to investigate the role and molecular mechanism of PtrNF-YA6 in secondary cell wall (SCW) formation in Populus trichocarpa. We found that PtrNF-YA6 protein was localized in the nucleus and had no transcriptional activating activity. Overexpression of PtrNF-YA6 had an inhibitory effect on plant growth and development and significantly suppressed hemicellulose synthesis and SCW thickening in transgenic plants. Yeast one-hybrid and ChIP-PCR assays revealed that PtrNF-YA6 directly regulated the expression of hemicellulose synthesis genes (PtrGT47A-1, PtrGT8C, PtrGT8F, PtrGT43B, PtrGT47C, PtrGT8A and PtrGT8B). In conclusion, PtrNF-YA6 can inhibit plant hemicellulose synthesis and SCW thickening by regulating the expression of downstream SCW formation-related target genes.

Tensile and Compressive Properties of Woven Fabric Carbon Fiber-Reinforced Polymer Laminates Containing Three-Dimensional Microvascular Channels.

Microvascular self-healing composite materials have significant potential for application and their mechanical properties need in-depth investigation. In this paper, the tensile and compressive properties of woven fabric carbon fiber-reinforced polymer (CFRP) laminates containing three-dimensional microvascular channels were investigated experimentally. Several detailed finite element (FE) models were established to simulate the mechanical behavior of the laminate and the effectiveness of different models was examined. The damage propagation process of the microvascular laminates and the influence of microvascular parameters were studied by the validated models. The results show that microvascular channels arranged along the thickness direction (z-direction) of the laminates are critical locations under the loads. The channels have minimal effect on the stiffness of the laminates but cause a certain reduction in strength, which varies approximately linearly with the z-direction channel diameter within its common design range of 0.1~1 mm. It is necessary to consider the resin-rich region formed around microvascular channels in the warp and weft fiber yarns of the woven fabric composite when establishing the FE model. The layers in the model should be assigned with equivalent unidirectional ply material in order to calculate the mechanical properties of laminates correctly.

Effects of Halloysite Nanotubes and Multi-walled Carbon Nanotubes on Kruppel-like Factor 15-Mediated Downstream Events in Mouse Hearts After Intravenous Injection.

Halloysite nanotubes (HNTs) are nanomaterials (NMs) derived from natural clays and have been considered as biocompatible NMs for biomedical uses. However, the cardiovascular toxicity of HNTs has not been thoroughly investigated. In this study, we compared the cardiotoxicity of HNTs and multi-walled carbon nanotubes (MWCNTs), focusing on the changes in Kruppel-like factor (KLF)-mediated signaling pathways. Mice were intravenously injected with 50 µg NMs, once a day, for 5 days, and then mouse hearts were removed for experiments. While HNTs or MWCNTs did not induce obvious pathological changes, RNA-sequencing data suggested the alterations of KLF gene expression. We further confirmed an increase of Klf15 positive cells, accompanied by changes in Klf15-related gene ontology (GO) terms. We noticed that most of the changed GO terms are related with the regulation of gene expression, and we confirmed that the NMs increased myoneurin (Mynn) but decreased snail family transcriptional repressor 1 (Snai1), two transcription factors (TFs) related with Klf15. Besides, the changed GO terms also include metal ion binding and positive regulation of glucose import, and we verified an increase of phosphoenolpyruvate carboxykinase 1 (Pck1) and insulin receptor (Insr). However, HNTs and MWCNTs only showed minimal impact on cell death signaling pathways, and no increase in apoptotic sites was observed after NM treatment. We concluded that intravenous administration of HNTs and MWCNTs activated a protective TF, namely Klf15 in mouse aortas, to alter gene expression and signaling pathways related with metal ion binding and glucose import.

Multilevel-Regulated Metal-Organic Framework Platform Integrating Pore Space Partition and Open-Metal Sites for Enhanced CO2 Photoreduction to CO with Nearly 100% Selectivity.

Rational design and regulation of atomically precise photocatalysts are essential for constructing efficient photocatalytic systems tunable at both the atomic and molecular levels. Herein, we propose a platform-based strategy capable of integrating both pore space partition (PSP) and open-metal sites (OMSs) as foundational features for constructing high-performance photocatalysts. We demonstrate the first structural prototype obtained from this strategy: pore-partitioned NiTCPE-pstp (TCPE = 1,1,2,2-tetra(4-carboxylphenyl)ethylene, pstp = partitioned stp topology). Nonpartitioned NiTCPE-stp is constructed from six-connected [Ni3(µ3-OH)(COO)6] trimer and TCPE linker to form 1D hexagonal channels with six coplanar OMSs directed at channel centers. After introducing triangular pore-partitioning ligands, half of the OMSs were retained, while the other half were used for PSP, leading to unprecedented microenvironment regulation of the pore structure. The resulting material integrates multiple advanced properties, including robustness, wider absorption range, enhanced electronic conductivity, and high CO2 adsorption, all of which are highly desirable for photocatalytic applications. Remarkably, NiTCPE-pstp exhibits excellent CO2 photoreduction activity with a high CO generation rate of 3353.6 µmol g-1 h-1 and nearly 100% selectivity. Theoretical and experimental studies show that the introduction of partitioning ligands not only optimizes the electronic structure to promote the separation and transfer of photogenerated carriers but also reduces the energy barrier for the formation of *COOH intermediates while promoting CO2 activation and CO desorption. This work is believed to be the first example to integrate PSP strategies and OMSs within metal-organic framework (MOF) photocatalysts, which provides new insight as well as new structural prototype for the design and performance optimization of MOF-based photocatalysts.

The impact of tax reduction on enterprises' financialization-A quasi-natural experiment based on the reduction of VAT rate.

This study examines the influence of the reduction in value-added tax (VAT) rates in China during 2018 and 2019 on corporate financialization. By employing a difference-in-differences model and utilizing data from Chinese A-share listed companies between 2017 and 2020, we assess the effects of tax reduction policies. Moreover, it achieves this outcome through three main pathways: alleviating financing constraints, boosting fixed asset investment, and weakening corporate financial arbitrage motives. Further analysis demonstrates that the inhibitory effect of VAT rate reduction on corporate financialization is more pronounced for non-manufacturing companies, businesses reliant on the basic tax rate as their primary revenue source, companies with low intermediate input rates, and those with a strong ability to shift the tax burden. Additionally, debt financing costs play a crucial role in moderating the relationship between tax reduction policies and corporate financialization. The conclusions drawn from this study provide valuable empirical evidence that can contribute to the refinement of VAT reduction policies and the prevention and resolution of financialization at the micro-level.

Application and Research Status of Long-Wavelength Fluorescent Carbon Dots.

This article discusses the application and research status of long-wavelength fluorescent carbon dots. Currently, there are two main methods for synthesising carbon dots (CDs), either from top to bottom, according to the bulk material, or from bottom to top, according to the small molecules. In previous research, mainly graphite and carbon fibres were used as raw materials with which to prepare CDs, using methods such as arc discharge, laser corrosion, and electrochemistry. These preparation methods have low quantum efficiencies and afford CDs that are limited to blue short-wavelength light emissions. With advancing research, the raw materials used for CD preparation have expanded from graphite to biomaterials, such as strawberry, lime juice, and silkworm chrysalis, and carbon-based molecules, such as citric acid, urea, and ethylenediamine (EDA). The preparation of CDs using carbon-based materials is more rapid and convenient because it involves the use of microwaves, ultrasonication, and hydrothermal techniques. Research on developing methods through which to prepare CDs has made great progress. The current research in this regard is focused on the synthesis of CDs, including long-wavelength fluorescent CDs, with a broader range of applications.

Superhydrophobic Pseudosupertetrahedral Sulfido Metalate Clusters for Constructing Liquid Marbles.

One pseudopentasupertetrahedral chalcogenidometalate cluster, [(BuSn)3SnCd4S13(OH)]·6(H+DMP) (PPS-1; H+DMP = protonated 3,5-dimethylpiperidine), has been isolated by use of an organotin precursor. They are arranged to generate two types of tetrahedrally patterned cages, which further interconnect to form a diamond network. Owing to the covalent attachment of abundant alkyl groups, PPS-1 exhibits excellent hydrophobicity and could be used as an assembly substance for building liquid marbles.

Structure and in vitro digestion characteristics of skim goat milk protein during processing: effects of fat separation.

BACKGROUND: Although nonfat milk has been used worldwide in the industrial dairy process, little is known about the effects of fat separation during the manufacturing process on skim milk's structural and digestive properties. This study investigated the effects of the manufacturing process on the structure and in vitro digestion properties of skim goat milk, particularly emphasizing fat separation. RESULTS: Changes in the surface charge and hydrophobicity of milk proteins caused by fat separation resulted in oxidation and aggregation in the subsequent homogenization, heat and spray-drying processing, which affected its digestibility. Compared with separation by dish separator (DS), skim milk after tubular centrifugal separation (CS) showed a higher initial and final digestibility. The CS samples also had a lower surface hydrophobicity level and higher free sulfhydryl content, ζ-potential, and average particle size (P < 0.05). Goat milk protein after CS was more readily oxidized and aggregated during the subsequent homogenization and heat treatment, as evidenced by the higher carbonyl content and particle size. Centrifugal separation also converted more ß-sheets to α-helices, thus promoting the aggregation of oxidized skim milk protein. CONCLUSION: The skim milk after CS and DS demonstrated different structural and digestive properties. Skim goat milk products after CS were more susceptible to oxidant-induced protein structural changes, resulting in higher protein digestibility. These findings provide insights into the mechanism involved in the control of gastric digestion of skim milk during manufacturing process. © 2023 Society of Chemical Industry.

Recent Advances in Pickering Double Emulsions and Potential Applications in Functional Foods: A Perspective Paper.

Double emulsions are complex emulsion systems with a wide range of applications across different fields, such as pharmaceutics, food and beverage, materials sciences, personal care, and dietary supplements. Conventionally, surfactants are required for the stabilization of double emulsions. However, due to the emerging need for more robust emulsion systems and the growing trends for biocompatible and biodegradable materials, Pickering double emulsions have attracted increasing interest. In comparison to double emulsions stabilized solely by surfactants, Pickering double emulsions possess enhanced stability due to the irreversible adsorption of colloidal particles at the oil/water interface, while adopting desired environmental-friendly properties. Such advantages have made Pickering double emulsions rigid templates for the preparation of various hierarchical structures and as potential encapsulation systems for the delivery of bioactive compounds. This article aims to provide an evaluation of the recent advances in Pickering double emulsions, with a special focus on the colloidal particles employed and the corresponding stabilization strategies. Emphasis is then devoted to the applications of Pickering double emulsions, from encapsulation and co-encapsulation of a wide range of active compounds to templates for the fabrication of hierarchical structures. The tailorable properties and the proposed applications of such hierarchical structures are also discussed. It is hoped that this perspective paper will serve as a useful reference on Pickering double emulsions and will provide insights toward future studies in the fabrication and applications of Pickering double emulsions.

Analyzing evidence-based falls prevention data with significant missing information using variable selection after multiple imputation.

Falls are the leading cause of fatal and non-fatal injuries among older adults. Evidence-based fall prevention programs are delivered nationwide, largely supported by funding from the Administration for Community Living (ACL), to mitigate fall-related risk. This study utilizes data from 39 ACL grantees in 22 states from 2014 to 2017. The large amount of missing values for falls efficacy in this national database may lead to potentially biased statistical results and make it challenging to implement reliable variable selection. Multiple imputation is used to deal with missing values. To obtain a consistent result of variable selection in multiply-imputed datasets, multiple imputation-stepwise regression (MI-stepwise) and multiple imputation-least absolute shrinkage and selection operator (MI-LASSO) methods are used. To compare the performances of MI-stepwise and MI-LASSO, simulation studies were conducted. In particular, we extended prior work by considering several circumstances not covered in previous studies, including an extensive investigation of data with different signal-to-noise ratios and various missing data patterns across predictors, as well as a data structure that allowed the missingness mechanism to be missing not at random (MNAR). In addition, we evaluated the performance of MI-LASSO method with varying tuning parameters to address the overselection issue in cross-validation (CV)-based LASSO.

Ultrasound improves the thermal stability and binding capacity of ovomucin by promoting the dissociation of insoluble ovomucin aggregates.

Ovomucin (OVM) is a natural glycoprotein with various biological activities but poor solubility. This study aimed to enhance the solubility of OVM by using an ultrasonic-assisted method. The effect of ultrasound (US) on the structure, thermal stability and biological functions of OVM aggregates was evaluated. It was found that insoluble OVM aggregates were dissociated and the solubility increased significantly to 90.0 % after US under 400 W for 45 min. US also improved the onset temperature (To) and denaturation temperature (Td) of OVM. More importantly, the cholesterol binding capacity of both OVM and its digestion products were significantly improved after US (p < 0.05). The gastrointestinal digestion products of US-OVM also showed higher α-amylase and α-glucosidase inhibition than native OVM aggregates. US-induced dissociation of OVM aggregates and the conversion of ß-sheet and ß-turn to random coil, resulting in the exposure of hydrophobic binding sites may be an important reason for the enhanced stability and adsorption capacity. These findings suggested that US was an effective method for preparing soluble OVM and improved its adsorption capacity, which can further facilitate the application of OVM in the food industry.

Detection of Cobalamin and In Vitro Cell Imaging Based on Nitrogen-Doped Yellow Fluorescent Carbon Dots with Nano Architectonics.

As novel fluorescent nanomaterials, carbon dots have attracted increasing research attention because of their simple synthesis, robust fluorescence, low toxicity, and easy functionalisation. Previous research was focused on preparing carbon dots from biomass and chemical materials; however, most of these carbon dots exhibited blue fluorescence. Moreover, the fluorescence quantum yield was generally low, significantly limiting their application in biological imaging. To broaden the application scope of carbon dots, this study prepared long-wavelength emitting nano-carbon dots that exhibited increased quantum yield. Novel N-doped yellow fluorescent nano-carbon dots (Y-CDs) were synthesised via a hydrothermal method using L-tartaric acid and urea as the precursors. The Y-CDs had a high quantum yield (15.9%) and demonstrated photostability at various pHs, temperatures, and ionic strengths. The Y-CDs could detect cobalamin effectively and selectively, showing a linear relationship between fluorescence intensity and cobalamin concentration. The related coefficient was 0.997, and the detection limit was 2.101 µmol/L. In addition, the Y-CDs were successfully used as an imaging probe for MDA-MB-231 cells. Therefore, the Y-CDs developed in this study can be used for cobalamin detection and cell imaging.

Research Progress of Polymers/Inorganic Nanocomposite Electrical Insulating Materials.

With the rapid development of power, energy, electronic information, rail transit, and aerospace industries, nanocomposite electrical insulating materials have been begun to be widely used as new materials. Polymer/inorganic nanocomposite dielectric materials possess excellent physical and mechanical properties. In addition, numerous unique properties, such as electricity, thermal, sound, light, and magnetic properties are exhibited by these materials. First, the macroscopic quantum tunneling effect, small-size effect, surface effect, and quantum-size effect of nanoparticles are introduced. There are a few anomalous changes in the physical and chemical properties of the matrix, which are caused by these effects. Second, the interaction mechanism between the nanoparticles and polymer matrix is introduced. These include infiltration adsorption theory, chemical bonding, diffusion theory, electrostatic theory, mechanical connection theory, deformation layer theory, and physical adsorption theory. The mechanism of action of the interface on the dielectric properties of the composites is summarized. These are the interface trap effect, interface barrier effect, and homogenization field strength effect. In addition, different interfacial structure models were used to analyze the specific properties of nanocomposite dielectric materials. Finally, the research status of the dielectric properties of nanocomposite dielectric materials in the electrical insulation field is introduced.

Study of the Electrical Conductivity Characteristics of Micro and Nano-ZnO/LDPE Composites.

Polyethylene, a thermoplastic resin made by ethylene polymerization, is widely used in electrical insulation. In this study, low-density polyethylene (LDPE) is used as a matrix with micro- and nano-ZnO particles as a filler to produce different proportions of micro- and nano-ZnO composites by melt blending. These samples are characterized by Polarized Light Microscopy (PLM) and FTIR tests, with their conductance measured under different field strengths. The current density vs. electric field strength (J-E) curve of micro- and nano-ZnO composites under different field strengths are measured and analyzed. The J-E curves of different composites at different temperatures are measured to explore conductance with temperature. The results of these tests showed that nano-ZnO composites successfully suppressed conductivity at elevated temperatures and electric field strengths, while micro-ZnO composites increased the conductivity relative to pure LDPE.

Effect of Cooling Medium on LDPE Dielectric Properties.

Polyethylene, with its excellent mechanical and dielectric properties is used as an insulator for high-voltage direct current (HVDC) transmission. In ultra-high-voltage direct current (UHVDC) transmission, the ageing of insulation materials caused by space charge under high DC voltage becomes serious. Therefore, restraining the space charge and improving the dielectric properties of HVDC cables is important. In this study, low-density polyethylene (LDPE) was used as the raw material and combined with cooling media in a vulcanizing press. A polarizing microscope was used to observe the samples' crystal morphologies. The space charge accumulation and dispersion were detected using pulsed electro-acoustic. Additionally, dielectric properties such as electrical conductivity and dielectric frequency spectrum were tested. The grain size in the air-cooled LDPE samples was found to be large and unevenly dispersed. However, the grain sizes in the water and oil cooling LDPE samples were small. The mean charge density of the oil cooling samples was the lowest. Under a short circuit measurement, more space charges were found in the natural and rapid air cooling samples. The mean charge densities of these two samples were high, with a fast decay rate. With an 8 and 50 kV/mm electric field strength, the oil cooling samples' conductivity was the highest and lowest, respectively.

Diagnosis of Metacarpophalangeal Synovitis with Musculoskeletal Ultrasound Images.

Rheumatoid arthritis (RA) is a chronic autoimmune disease that can result in considerable disability and pain. The metacarpophalangeal (MCP) joint is the most common diseased joint in RA. In clinical practice, MCP synovitis is commonly diagnosed on the basis of musculoskeletal ultrasound (MSUS) images. However, because of the vague criteria, the consistency in grading MCP synovitis based on MSUS images fluctuates between ultrasound imaging practitioners. Therefore, a new method for diagnosis of MCP synovitis is needed. Deep learning has developed rapidly in the medical area, which often requires a large-scale data set. However, the total number of MCP-MSUS images fell far short of the demand, and the distribution of different medical grades of images was unbalanced. With use of the traditional image augmentation methods, the diversity of the data remains insufficient. In this study, a high-resolution generative adversarial network (HRGAN) method that generates enough images for network training and enriches the diversity of the training data set is described. In comparison experiments, our proposed diagnostic system based on MSUS images provided more consistent results than those provided by clinical physicians. As the proposed method is image relevant, this study might provide a reference for other medical image classification research with insufficient data sets.

Incidence and Risk Factors for Antiplatelet Therapy-Related Bleeding Complications Among Elderly Patients After Coronary Stenting: A Multicenter Retrospective Observation.

Purpose: To determine the incidence and risk factors of bleeding events as well as assess the performance of the PRECISE-DAPT score in elderly patients (≥75 years) who underwent percutaneous coronary intervention (PCI) and one-year dual antiplatelet therapy (DAPT). Methods: A total of 940 patients (≥75 years) who received PCI and one-year DAPT were retrospectively enrolled into the study. The multivariable logistic regression analysis was conducted to identify risk factors of antiplatelet-related bleeding complications. The receiver operating characteristic (ROC) curve analysis and the Delong test were performed to obtain the optimized PRECISE-DAPT score. Results: It was observed that 89 (9.47%) patients suffered bleeding complications, while 37 (3.94%) of them had the Bleeding Academic Research Consortium (BARC, type ≥2) bleeding events. We stratified the PRECISE-DAPT score in tertiles (T1: ≤23; T2:24 to 32; T3: ≥33) and found that BARC ≥ 2 type bleeding occurred more frequently in T3 than in T1 and T2 (8.25 vs. 1.46% vs. 2.40%, p <0.05). The ROC curve analysis revealed that the PRECISE-DAPT score cutoff for BARC ≥2 type bleeding prediction was 33. In comparison with the current recommended cutoff score of 25 (AUC: 0.608, based on ROC analysis), the Delong test indicated significantly improved ability for predicting BARC ≥ 2 type bleeding events using the proposed cutoff value of 33, AUC of 0.676 (p = 0.03), and Brier Score of 0.04. The multivariable logistic regression analysis demonstrated that the PRECISE-DAPT score ≥ 33 [OR: 3.772; 95% CI (1.229, 11.578); p = 0.02] was associated with BARC ≥ 2 type bleeding event, along with a history of hemorrhagic stroke [OR: 6.806; 95% CI (1.465, 31.613); p = 0.014], peptic ulcer [OR: 3.871; 95% CI (1.378, 10.871); p = 0.01], and/or myocardial infarction [MI, OR: 3.081; 95% CI (1.140, 8.326); p = 0.027]. Conclusion: A higher PRECISE-DAPT score of 33 might be a more reasonable cutoff value for predicting BARC ≥2 type bleeding risk in CAD patients (≥75 years). In addition, the history of hemorrhagic stroke, peptic ulcer, and myocardial infarction were identified as the risk factors of BARC ≥2 type bleeding events.

Monomeric CRP Aggravates Myocardial Injury After Myocardial Infarction by Polarizing the Macrophage to Pro-Inflammatory Phenotype Through JNK Signaling Pathway.

OBJECTIVE: A polarized macrophage response plays a critical role in the pathophysiological process of myocardial infarction (MI). Several studies have shown a pro-inflammatory role for monomeric C-reactive protein (mCRP) in cardiovascular disease. However, the mechanism of how mCRP regulates macrophage phenotype switching remains unknown. In the present study, the effect of mCRP on macrophage polarization and its pathological function in myocardial repair after myocardial infarction was investigated. METHODS: MI was induced by permanent ligation of the left anterior descending coronary artery in ICR mice. Adult mice were injected with mCRP (2.5 mg/kg) with or without SP600125 (15 mg/kg, JNK inhibitor) 45 min before MI. The cardiac function, scar size as well as cardiac fibrosis, infiltration of inflammatory cells, and the level of proteins in the JNK signaling pathway in infarcted myocardium were assessed. In addition, the phenotypic characterization of macrophages was further measured by ELISA, flow cytometry and quantitative RT-PCR in cultured THP-1 cells or peritoneal macrophages. RESULTS: Cardiac function deterioration, ventricular dilatation and fibrosis were exacerbated in mice pretreatment with mCRP following MI. Meanwhile, an increased accumulation of infiltrated inflammatory cells in infarcted myocardium was observed in the mCRP group. Moreover, activation of the JNK signaling pathway was markedly elevated in mCRP treated animals post-MI. In contrast, pharmacological inhibition of JNK phosphorylation activity by SP600125 muted the detrimental effects of mCRP in MI mice. Furthermore, in vitro and in vivo co-culture experiments showed that mCRP shifted macrophage polarization towards pro-inflammatory phenotypes, and this polarization could be abolished by sp600125. CONCLUSION: Taken together, our results imply that mCRP impairs myocardial repair after myocardial infarction by polarizing the macrophages into the pro-inflammatory M1 phenotype via the JNK-dependent pathway.

The Research of Conductivity and Dielectric Properties of ZnO/LDPE Composites with Different Particles Size.

Nanocomposites exhibit a high dielectric strength, whereas microcomposites exhibit a high thermal conductivity. In this study, good insulating materials were developed on the basis of the synergetic effect of micro- and nanoparticles, which were used as inorganic fillers. With a double-melting blend, nano-ZnO/low density polyethylene (LDPE), micro-ZnO/LDPE, and micro-nano-ZnO/LDPE composites were prepared, according to the scanning electron microscope test, polarization microscope test, conductivity test, breakdown test, and dielectric spectrum test, the dielectric property of micro-nano-ZnO/LDPE was explored. The SEM test results showed that by adding a suitable proportion of ZnO particles, the inorganic particles could disperse uniformly without reuniting. The PLM test results showed that the micro- and nano-ZnO particles adding decreased the crystal size. The arrangement was regular and tight. The macroscopic results showed that the mass fraction of nanoparticles and microparticles were 3% and 2%, the samples conductivity was the lowest. The breakdown field strength of the nanocomposites increased. The breakdown field strength of nanocomposites with 1%, 3%, and 5% nanoparticle contents were 5%, 15%, and 10% higher than that of pure LDPE. The addition of inorganic particles resulted in new polarization modes: Ionic displacement polarization and interfacial polarization. The ZnO/LDPE composites exhibited a higher dielectric constant and dielectric loss factor than pure LDPE. However, with the increasing frequency, it took considerable time to attain interfacial polarization in the nanocomposite and micro-nanocomposite, thus decreasing the dielectric constant.

The Research of Crystalline Morphology and Breakdown Characteristics of Polymer/Micro-Nano-Composites.

In this article, low-density polyethylene (LDPE) was used as a matrix polymer, the Micro-ZnO and Nano-ZnO particles were used as the inorganic filler. With the melt blending method, the Nano-ZnO/LDPE(Nano-ZnO particles doping into LDPE), Micro-ZnO/LDPE(Micro-ZnO particles doping into LDPE) and Micro-Nano-ZnO/LDPE (Nano-ZnO and Micro-ZnO particles doping into LDPE in the same time) composites were prepared. Then, the inorganic filler and the composites were dealt with structural characterizations and analysis by Fourier transform infrared (FTIR), Polarization microscope (PLM), and Differential scanning calorimeter (DSC). Besides, these samples were dealt with (alternating current) AC breakdown performance test. The micro-experimental results showed that the Micro-ZnO and Nano-ZnO particles doping reduced the crystal size and increased the crystallization rate. With the change of cell structure, the crystallinity of composites increased. The crystallinity order of different samples was as follows: LDPE < Micro-ZnO/LDPE < Nano-ZnO/LDPE < Micro-Nano-ZnO/LDPE. From the breakdown of the experimental result, with the same mass fraction of the different inorganic doping of particles, the breakdown strength of these composites was different. The Nano-ZnO particle doping could improve the breakdown strength of composites effectively. Among them, the breakdown strength of Nano-ZnO/LDPE and Micro-Nano-ZnO/LDPE were 11% higher and 1.3% lower than that of pure LDPE, respectively. Meanwhile, the breakdown strength of Micro-composite was the lowest but its Weibull shape coefficient was the highest. Therefore, the Micro-ZnO doping was helpful for the Nano-ZnO dispersing in the matrix, which produced the Micro-Nano-synergy effects better.