Scalable Dual In Situ Synthesis of Polyester Nanocomposites for High-Energy Storage.

Incorporating ultralow loading of nanoparticles into polymers has realized increases in dielectric constant and breakdown strength for excellent energy storage. However, there are still a series of tough issues to be dealt with, such as organic solvent uses, which face enormous challenges in scalable preparation. Here, a new strategy of dual in situ synthesis is proposed, namely polymerization of polyethylene terephthalate (PET) synchronizes with growth of calcium borate nanoparticles, making polyester nanocomposites from monomers directly. Importantly, this route is free of organic solvents and surface modification of nanoparticles, which is readily accessible to scalable synthesis of polyester nanocomposites. Meanwhile, uniform dispersion of as ultralow as 0.1 wt% nanoparticles and intense bonding at interfaces have been observed. Furthermore, the PET-based nanocomposite displays obvious increases in both dielectric constant and breakdown strength as compared to the neat PET. Its maximum discharged energy density reaches 15 J cm-3 at 690 MV m-1 and power density attains 218 MW cm-3 under 150 Ω resistance at 300 MV m-1, which is far superior to the current dielectric polymers that can be produced at large scales. This work presents a scalable, safe, low-cost, and environment-friendly route toward polymer nanocomposites with superior capacitive performance.

Optimizing the dielectric constant of the shell layer in core-shell structures for enhanced energy density of polymer nanocomposites.

Improved dielectric constant and breakdown strength facilitates excellent energy storage density of polymer dielectrics, which is positive to miniaturize dielectric capacitors in electronic and electrical systems. Although coating polar substances on nanoparticles enhances the dielectric constants of polymer nanocomposites, it usually causes local electric field concentration, leading to poor breakdown strength. Here, fluoropolymers with tailorable fluorine content (PF0, PF30 and PF60) are coated on BaTiO3 (BT) nanoparticles to construct typical core-shell structures that are further blended with poly(vinylidenefluoride-co-hexafluoropropylene) (P(VDF-HFP)) to obtain BT@PF/P(VDF-HFP) nanocomposites. Uniform dispersion of nanoparticles and excellent compatibility of interfaces are observed for the samples. In addition, the dielectric constant gradually increases from 8.03 to 8.26 to 9.12 for the nanocomposites filled with 3 wt% BT@PF0, BT@PF30 and BT@PF60, respectively. However, 3 wt% BT@PF30/P(VDF-HFP) has the highest breakdown strength (455 kV mm-1) among the nanocomposites, which is as good as neat P(VDF-HFP). More importantly, BT@PF30 rather than BT@PF60 possesses the maximum discharged energy density (11.56 J cm-3 at 485 kV mm-1), which is about 1.65 times that of neat P(VDF-HFP). This work proposes a facile experimental route to optimize the dielectric constants of the shell layer to couple the dielectric constants between the nanoparticles, shell layer and polymer matrix, which contributes to alleviating the local electric field concentration for excellent breakdown strength and electrical energy storage of polymer nanocomposites.

A novel bee-friendly peptidomimetic insecticide: Synthesis, aphicidal activity and 3D-QSAR study of insect kinin analogs at Phe2 modification.

BACKGROUND: As one of the most abundant and destructive pests in agriculture, aphids cause significant damage to crops due to their sap-taking and as virus vectors. Chemical insecticides are the most effective method to control aphids, but they bring insecticide resistance problems and harm nontarget organisms, especially bees, therefore the search for novel eco-friendly aphid control agents with low bee toxicity is urgent. Insect kinins are a class of small neuropeptides that control important functions in insects. In our previous study, we found insect kinin analog IV-3 has good aphicidal activity and the location of the aromatic ring on the side chain of Phe2 is the key to the formation of the ß-turn resulting in the biological activity of insect kinin analogs. However, there are few studies on insect kinin Phe2 substitution and modification, and its structure-activity relationship is still unclear. RESULTS: In this project, 44 insect kinin analogs with the Phe2 modification, replacing it with different natural or unnatural amino acids, were designed and synthesized based on the lead IV-3 to explore the role of the Phe2 residues. Bioassays with soybean aphids of Aphis glycines indicated that nine analogs have better aphicidal activity than the lead IV-3. In particular, compound L25 exhibits excellent aphicidal activity (LC50  = 0.0047 mmol L-1 ) and has low toxicity to bees. Furthermore, a reliable three-dimensional quantitative structure-activity relationship (3D-QSAR) was established to produce a helpful clue that introducing hydrophobic groups away from the backbone chain is beneficial to improve aphicidal activity. CONCLUSION: The residue Phe2 of insect kinin analogs is the key position and has a significant impact on the activity. L25 has a high toxicity for aphids, while a low toxicity to bees, and therefore can be considered as a lead compound to develop new biosafe aphid control agents. Finally, we provide a useful 3D-QSAR model as theoretical guidance for further structural optimization. © 2022 Society of Chemical Industry.

High loading BaTiO3 nanoparticles chemically bonded with fluorinated silicone rubber for largely enhanced dielectric properties of polymer nanocomposites.

Integrating high-loading dielectric nanoparticles into polar polymer matrices potentially can profit the intrinsic polarization of each phase and allow for greatly enhanced dielectric properties in polymer nanocomposites. It is however challenging to achieve desirable highly filled polar polymer composites because of the lack of efficient approaches to disperse nanoparticles and maintain interfacial compatibility. Here, we report a versatile route to fabricate highly filled barium titanate/fluorinated silicone rubber (BT/FSR) nanocomposites by "thiol-ene click" and isostatic pressing techniques. The loaded BT nanoparticles (from 82 wt% to 90 wt%) are chemically bonded with FSR in the nanocomposites. The existence of the polar group (-CH2CF3) of the polymer matrix does not affect the uniform dispersion of the nanoparticles or the good interfacial compatibility. The 90 wt% BT/FSR nanocomposite shows the highest dielectric constant of 57.8 at 103 Hz, while the loss tangent can be kept below 0.03. Besides, BT/FSR nanocomposites display higher breakdown strength than BT/SR nanocomposites. This work offers a facile strategy towards superior dielectric properties of polymer nanocomposites.

[Association between matrix metalloproteinase-8 -799C/T polymorphism and instability of carotid plaque].

OBJECTIVE: To investigate the association between a -799C/T polymorphism in the promotor region of matrix metalloproteinase-8 (MMP-8) gene and instability of carotid plaque in Chinese Han population. METHODS: A total of 451 acute infarction patients from the Department of Neurology of Taizhou Hospital were divided into carotid vulnerable plaque group and carotid stable plaque group according to the results of carotid B-mode ultrasonography. Serum MMP -8 level was measured by the means of enzyme-linked immunosorbent assay (ELISA). At the same time, the MMP-8 -799C/T polymorphism was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. RESULTS: Serum level of MMP-8 in the carotid vulnerable plaque group was higher than that in the carotid stable plaque group (t= 2.894, P= 0.004). The genotype distribution of -799C/T polymorphism between the two groups was significantly different (Chi-square = 13.65, P= 0.000). Serum level of MMP-8 in patients with TT genotype was higher than that in patients with CC genotype (t= 3.141, P= 0.001). CONCLUSION: The present study suggested that serum level of MMP-8 and the -799C/T polymorphism of MMP-8 gene are associated with carotid vulnerable plaque in Chinese Han population, and the T allele may be a predictor for the susceptibility of carotid vulnerable plaque.

[Relationship of polymorphism of SG13S114A/T in ALOX5AP gene with atherosclerotic cerebral infarction].

OBJECTIVE: To investigate the relationship of the polymorphism of SG13S114A/T in ALOX5AP gene with atherosclerotic cerebral infarction (ACI). METHODS: By polymerase chain reaction and restriction fragment length polymorphism, polymorphism of SG13S114A/T in ALOX5AP gene in 412 cases with ACI and 368 non-ACI controls were analyzed. RESULT: There were no statistically significant differences in the ALOX5AP gene SG13S114 AA genotype and A allele frequencies between ACI group and control group (P>0.05). CONCLUSION: The results do not support genotype SG13S114 A allele as the risk gene for ACI.control group.

[Study on expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 in brain tissue adjacent to hemorrhage after brain hemorrhage in human].

OBJECTIVE: To investigate the expression and significance of matrix metalloproteinase-2 (MMP-2) and MMP-9 in peri-hematoma brain tissues after acute brain hemorrhage in human. METHODS: Forty-two patients with acute brain hemorrhage received surgery, the brain tissues adjacent to hemorrhagic site were obtained during surgery, and positive expressions of MMP-2 and MMP-9 were determined with immunohistochemical staining. Brain tissues from 30 patients with cerebral trauma were obtained to serve as controls. RESULTS: The positive expressions of MMP-2 and MMP-9 in focal brain tissues were significantly elevated in early acute brain hemorrhage. Compared with 28 and 27 cases with MMP-2 and MMP-9 positive expression respectively in control group, there were 39 and 37 cases with MMP-2 and MMP-9 positive expression respectively in acute brain hemorrhage group. There were no significant differences between two groups (both P>0.05). CONCLUSION: MMP-2 and MMP-9 might contribute to brain edema formation in the acute intra-cerebral hemorrhage of human.