The Recent Advances of Polymer-POSS Nanocomposites With Low Dielectric Constant.

This study provides a comprehensive overview of the preparation methods for polyhedral oligomeric silsesquioxane (POSS) monomers and polymer/POSS nanocomposites. It focuses on the latest advancements in using POSS to design polymer nanocomposites with reduced dielectric constants. The study emphasizes exploring the potential of POSS, either alone or in combination with other materials, to decrease the dielectric constant and dielectric loss of various polymers, including polyimides, bismaleimide resins, poly(aryl ether)s, polybenzoxazines, benzocyclobutene resins, polyolefins, cyanate ester resins, and epoxy resins. In addition, the research investigates the impact of incorporating POSS on improving the thermal properties, mechanical properties, surface properties, and other aspects of these polymers. The entire study is divided into two parts, discussing systematically the role of POSS in reducing dielectric constants during the preparation of POSS composites using both physical blending and chemical synthesis methods. The goal of this research is to provide valuable strategies for designing a new generation of low dielectric constant materials suitable for large-scale integrated circuits in the semiconductor materials domain.

Self-Healing Heterometallic Supramolecular Polymers Constructed by Hierarchical Assembly of Triply Orthogonal Interactions with Tunable Photophysical Properties.

Here, we present a method for the building of new bicyclic heterometallic cross-linked supramolecular polymers by hierarchical unification of three types of orthogonal noncovalent interactions, including platinum(II)-pyridine coordination-driven self-assembly, zinc-terpyridine complex, and host-guest interactions. The platinum-pyridine coordination provides the primary driving force to form discrete rhomboidal metallacycles. The assembly does not interfere with the zinc-terpyridine complexes, which link the discrete metallacycles into linear supramolecular polymers, and the conjugation length is extended upon the formation of the zinc-terpyridine complexes, which red-shifts the absorption and emission spectra. Finally, host-guest interactions via bis-ammonium salt binding to the benzo-21-crown-7 (B21C7) groups on the platinum acceptors afford the cross-linked supramolecular polymers. By continuous increase of the concentration of the supramolecular polymer to a relatively high level, supramolecular polymer gel is obtained, which exhibits self-healing properties and reversible gel-sol transitions stimulated by various external stimuli, including temperature, K+, and cyclen. Moreover, the photophysical properties of the supramolecular polymers could be effectively tuned by varying the substituents of the precursor ligands.

Metallacycle-Cored Supramolecular Polymers: Fluorescence Tuning by Variation of Substituents.

Herein, we present a method for the preparation of supramolecular polymers with tunable fluorescence via the combination of metal-ligand coordination and phenanthrene-21-crown-7 (P21C7)-based host-guest interactions. A suite of rhomboidal metallacycles with different substituents were prepared via the coordination-driven self-assembly of a P21C7-based 60° diplatinum(II) acceptor and 120° dipyridyl donors. Upon variation of the substituents on the dipyridyl donors, the metallacycles exhibit emission wavelengths spanning the visible region (λmax = 427-593 nm). Metallacycle-cored supramolecular polymers were obtained via host-guest interactions between bis-ammonium salts and P21C7. The supramolecular polymers exhibit emission wavelengths similar to those of the individual metallacycles and higher fluorescent efficiency in solution and thin films. Utilizing a yellow-emitting supramolecular polymer thin film with high quantum yield (0.22), a white-light-emitting LED was fabricated by painting the thin film onto an ultraviolet LED. This study presents an efficient approach for tuning the properties of fluorescent supramolecular polymers and the potential of the metallacycle-cored supramolecular polymers as a platform for the fabrication of light-emitting materials with good processability and tunability.

Metal Coordination Stoichiometry Controlled Formation of Linear and Hyperbranched Supramolecular Polymers.

Controlling the topologies of polymers is a hot topic in polymer chemistry because the physical and/or chemical properties of polymers are determined (at least partially) by their topologies. This study exploits the host-guest interactions between dibenzo-24-crown-8 and secondary ammonium salts and metal coordination interactions between 2,6-bis(benzimidazolyl)-pyridine units with metal ions (Zn(II) and/or Eu(III) ) as orthogonal non-covalent interactions to prepare supramolecular polymers. By changing the ratios of the metal ion additives (Zn(NO3 )2 and Eu(NO3 )3 ) linkers to join the host-guest dimeric complex, the linear supramolecular polymers (100 mol% Zn(NO3 )2 per ligand) and hyperbranched supramolecular polymers (97 mol% Zn(NO3 )2 and 3 mol% Eu(NO3 )3 per ligand) are separately and successfully constructed. This approach not only expands topological control over polymeric systems, but also paves the way for the functionalization of smart and adaptive materials.

Functionalized lignin nanoparticles for producing mechanically strong and tough flame-retardant polyurethane elastomers.

There is a strong interest in developing environmentally friendly synthesis approaches for making polyurethane elastomers (PUE) with desirable mechanical performance and flame retardancy suitable for a variety of applications. Hence, in this study, a novel nano functionalized lignin nanoparticle (Nano-FL) containing nitrogen (N) and phosphorus (P) moieties was developed via mild grafting reactions combined with the ultrasound method. The Nano-FL incorporated in the PUE acted as both crosslinking agents and flame retardants. The novel Nano-FL showed good compatibility and dispersibility in the PUE matrix, thereby overcoming the weakening effect of adding traditional lignin flame retardants on the mechanical properties of the PUE materials. PUE/Nano-FL exhibited strong tensile properties. Compared with control neat PUE, with 10 wt% of Nano-FL addition, the PUE attained a limiting oxygen index as high as 29.8% and it also passed the UL-94 V-0 rating. Furthermore, Cone Calorimetry Test (CCT) showed that the addition of Nano-FL not only reduced the heat release rate and the total heat release but also decreased the total smoke production rate during combustion. The char residues of PUEs with Nano-FL showed a high oxidation resistance with dense and continuous structural morphologies. The combined barrier and quenching effects of the char layer provided excellent flame retardancy performance. The novel Nano-FL developed in this study showed excellent promises as green functional additives for enhancing mechanical, thermal and flame retardancy performance of a wide range of polymers.

All-trans Retinoic Acid-incorporated Glycol Chitosan Nanoparticles Regulate Macrophage Polarization in Pg-LPS-Induced Inflammation.

OBJECTIVE: The occurrence and development of inflammation are closely correlated to the polarization of macrophages. All-trans retinoic acid (ATRA) has been proven to promote the polarization of macrophages from M1 to M2, but this lacks an effective carrier to participate in the biological response. The present study aims to determine whether retinoic acid-incorporated glycol chitosan (RA-GC) nanoparticles can regulate macrophage polarization in Porphyromonas gingivalis-lipopolysaccharide (Pg-LPS)-induced inflammation. METHODS: Mouse 264.7 cell lines were treated with 1 µg/mL Pg-LPS to induce inflammation. After the effects of ATRA and RA-GC on the activity of macrophages were detected by CCK-8 assay, cells induced with Pg-LPS were assigned to the blank control group (GC) nanoparticles without ATRA, and experimental groups (GC nanoparticles loaded with different concentrations of ATRA: 1, 10 and 100 µg/mL). The effects of RA-GC on inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-10 and IL-12 in macrophages were detected by enzyme-linked immunosorbent assay (ELISA). Subsequently, the effects of GC nanoparticles loaded with/without ATRA on macrophage polarization in an inflammatory environment were detected by RT-PCR and Western blotting. RESULTS: The results revealed that RA-GC had no significant effect on macrophage activity. However, RA-GC could effectively inhibit the Pg-LPS-induced inflammatory factor expression in macrophages. Meanwhile, the experimental results confirmed that RA-GC could downregulate the expression of inducible nitric oxide synthase (iNOS) (a marker of M1 macrophages) and upregulate the expression of mannose receptor and Arginase-1 (a marker of M2 macrophages) in a dose-dependent manner. CONCLUSION: The present study confirms that RA-GC can promote the M2 polarization of macrophages in an inflammatory environment, and proposes this as a promising target for the clinical treatment of Pg-LPS-related diseases.

Chiral Assembly and Recognition of Seven Copper (II) Coordination Polymers from Tartaric Acid Derivative Ligands.

A pair of enantiomeric ligands, (2R,3R)-dibenzyl-2,3-bis(isonicotinoyloxy)succinate ((R,R)-L) and (2S,3S)-dibenzyl-2,3-bis(isonicotinoyloxy)succinate ((S,S)-L), are designed and synthesized. Seven copper (II) coordination polymers {[Cu((R,R)-L)Br2 (THF)] ⋅ CH3 CN} n (1 a) and {[Cu((S,S)-L)Br2 (THF)] ⋅ CH3 CN}n (1 b), {[Cu((R,R)-L)Cl2 (THF)] ⋅ CH3 CN}n (2 a) and {[Cu((S,S)-L)Cl2 (THF)] ⋅ CH3 CN}n (2 b), {[Cu((R,R)-L)(NO3 )2 (CH3 CN)]}n (3 a) and {[Cu((S,S)-L)(NO3 )2 (CH3 CN)]}n (3 b), {[Cu((R,R)-L)2 (CH3 CN)2 ](ClO4 )2 ⋅ 3CH3 CN}n (4) were obtained through the assemblies with CuBr2 , CuCl2 ⋅ 2H2 O, Cu(NO3 )2 ⋅ 3H2 O, Cu(ClO4 )2 ⋅ 6H2 O, respectively. Single-crystal X-ray diffraction and circular dichroism analysis demonstrate that 1 a-3 a, 1 b-3 b have a mono chiral one-dimensional (1D) chain-like spiral structure, while 4 have 1D chain-like structure whose metal centers have chiral propeller coordination environment. Ligand structure, anions and solvent systems have a regulatory effect on the formation of chiral helical structure. Further investigation has proved that 1 a can be used as circular dichroism spectrum probe for monitoring L-/D-cysteine and L-/D-penicillamine configuration and concentration in aqueous media based on ligand interchange mechanism.

Self-Healing Metallacycle-Cored Supramolecular Polymers Based on a Metal-Salen Complex Constructed by Orthogonal Metal Coordination and Host-Guest Interaction with Amino Acid Sensing.

A platinum(II) metallacycle-cored supramolecular network based on a metal-salen complex was successfully constructed by two orthogonal noncovalent interactions (host-guest interactions and metal coordination interactions). The obtained metallo-supramolecular polymer could further form gels when the concentration of metallacycle 1 was 160.0 mM. This gel exhibited multiple stimuli-responsive gel-sol phase transitions under different stimuli, such as temperature, competitive guests, etc. Moreover, it exhibited good self-healing properties and could be used as a turn-off sensor for thiol-containing amino acids.

The use of sel-ligating appliance can reduce inflammatory response to orthodontic force and keep periodontal health in orthodontic treatment.

OBJECTIVE: Orthodontics, as a common way of orthodontic treatment, is usually to maintain oral health and protect periodontal tissue. The self-ligating appliance technique, since its advent in the 1930s, have been rather popular ammong the majority of orthodontists. This study was to determine that self-ligating appliance can reduce inflammation in gingival crevicular fluid (GCF) of patients receiving orthodontic treatment and keep periodontal health. METHODS: The clinical data of 97 orthodontic patients admitted to the Department of Stomatology of Fujian Provincial Hospital, Fujian Provincial Clinical College of Fujian Medical University from March 2019 to March 2020 were analyzed retrospectively. Among them, 42 patients receiving orthodontic treatment with traditional MBT straight-wire appliance (SWA) were included in the control group (CG) and 55 patients treated with self-ligating appliance were collected as the observation group (OG). The two cohorts were compared with respect to the following aspects: curative effect, pain degree on the 1st, 2nd, 3rd, 5th and 7th day after wearing the appliance, oral related quality of life (QoL) before and after orthodontic treatment, satisfaction with the orthodontic treatment, periodontal condition, and GCF and inflammatory factor contents before, 3 months and 6 months after orthodontic treatment. RESULTS: OG had significantly higher therapeutic efficacy of orthodontic treatment than CG (P<0.05). At the initial stage of treatment, the pain degree in OG was obviously lower than that in CG (P<0.05). Compared with CG, the plaque index (PLI), sulcus bleeding index (SBI), gingival recession (GR), periodontal probing depth (PPD) and clinical attachment loss (CAL) were better in OG after orthodontic treatment, and the differences were statistically significant (P<0.05). The contents of GCF, prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) in OG were lower than those in CG after orthodontic treatment, with significant differences between the two groups (P<0.05). Oral related QoL and orthodontic satisfaction were higher in OG, and the differences were statistically significant (P<0.05). CONCLUSIONS: Compared with traditional SWA, the self-ligating appliance in orthodontic treatment contributes to higher efficacy and satisfaction, less local inflammatory reaction, and significantly improved periodontal condition and oral health of patients.

Improved performance of α-amylase immobilized on poly(glycidyl methacrylate-co-ethylenedimethacrylate) beads.

α-Amylase was successfully immobilized onto poly(glycidyl methacrylate-co-ethylenedimethacrylate) (PGMA/EDMA) beads with high immobilization efficiency of 87.8%. PGMA/EDMA beads with a relatively uniform diameter of 2-3 µm were prepared by single-step swelling polymerization. After amination with ethanediamine and activation with glutaraldehyde, PGMA/EDMA beads showed commendable α-amylase immobilization capacity of 35.1 mg g(-1) carrier. Compared with free form, immobilized α-amylase had increasement of 12.94 mg mL(-1) for Km and 0.124 mmol mL(-1) min(-1) for Vmax, improved acid resistance (the optimal pH from 7 to 5), presented better thermal stability by retaining 61% activity than 40% at 90 °C, and displayed high operational reusability by retaining 58% of its initial activity after nine uses. Moreover, less than 10% of the free enzyme and more than 80% of the immobilized enzyme retained activity after 180 min pre-incubation at 50 °C. The easy modification, high immobilization efficiency and good properties of immobilized α-amylase in the present study indicate that PGMA/EDMA beads are suitable for α-amylase immobilization. The enhancement of acid resistance and thermo stability is doubtless of benefit for the industrial use of α-amylase.

[Epidemiological and etiological characteristics of hand-foot-mouth disease in Ningbo, Zhejiang province, 2008-2011].

OBJECTIVE: To analyze the epidemiological characteristics of hand foot and mouth disease (HFMD) in Ningbo. METHODS: A descriptive analysis was conducted through the surveillance data of HFMD in Ningbo, Zhejiang province, from 2008 to 2011. Genes on EV71 and Cox A16 were amplified with RT-PCT from the stool samples of HFMD patients. Sequences were analyzed by bioinformatics software. RESULTS: 37 524 cases of HFMD were reported from 2008 to 2011, including 196 severe cases and 12 deaths. The reported incidence was 145.26 per 100 000 and the case fatality was 0.03%. Cases in children aged 5 or younger accounted for 95.89%, and the scattered cases accounted for 64.10%. Xiangshan and Ninghai counties had the highest incidence rates in Ningbo. The peak of incidence was from April to July. The number of male patients was obviously higher than females. 2394 cases of HFMD were laboratory confirmed and EV71 with the predominant epidemic strain. Data from phylogenetic analysis revealed that EV71 isolated from HFMD patients in Ningbo belonged to C4a evolution branch of C4 sub-genotype, with several transmission chains. Cox A16 belonged to B1 evolution branch. 53.48% of the healthy children in Ningbo showed EV71 antibody positive. The geometric mean of the antibody titer (GMT) was 11.23 (8.33 - 14.98) in healthy children. Cox A16 antibody was detected at 63.18% of the healthy children in Ningbo. GMT in healthy children was 12.61 (6.70 - 16.52). CONCLUSION: HFMD was highly endemic in Ningbo, with children under 5 years old were at high-risk. The major etiologic agent was EV71 which belonged to C4a in the C4 sub-genotypes. Cox A16 belonged to the B1 evolution branch, which were in line with the predominant virus circulating in the mainland of China.