Fluorine-Containing Covalent Organic Frameworks: Synthesis and Application.

Covalent organic frameworks (COFs) are a type of crystalline porous polymers that possess ordered structures and eternal pores. Because of their unique structural characteristics and diverse functional groups, COFs have been used in various application fields, such as adsorption, catalysis, separation, ion conduction, and energy storage. Among COFs, the fluorine-containing COFs (fCOFs) have been developed for special applications by virtue of special physical and chemical properties resulting from fluorine element, which is a nonmetallic halogen element and possesses strong electronegativity. In the organic chemistry field, introducing fluorine into chemicals enables those chemicals to exhibit many interesting properties, and fluorine chemistry increasingly plays an important role in the history of chemical development. The introduction of fluorine in COFs can enhance the crystallinity, porosity, and stability of COFs, making COFs having superior performances and some new applications. In this review, the synthesis and application of fCOFs are systematically summarized. The application involves photocatalytic production of hydrogen peroxide, photocatalytic water splitting, electrocatalytic CO2 reduction, adsorption for different substances (H2 , pesticides, per-/polyfluoroalkyl substances, polybrominated diphenyl ethers, bisphenols, and positively charged organic dye molecules), oil-water separation, energy storage (e.g., zinc-ion batteries, lithium-sulfur batteries), and proton conduction. Perspectives of remaining challenges and possible directions for fCOFs are also discussed.

Transition in plant-plant facilitation in response to soil water and phosphorus availability in a legume-cereal intercropping system.

BACKGROUND: The tradeoff between negative and positive interactions of facilitated species and facilitators may depend on the degree of resource availability in agroecosystems. However, the rhizospheric mechanisms driving trade-offs that occur along phosphorus (P) and water availability gradients have not yet been systematically clarified. We established three types of root isolation conditions (no barrier, nylon barrier and solid barrier) at different P and water addition levels to address the above issue in a maize-grass pea intercropping system. RESULTS: The total yield and biomass net effect (NE) and the relative interaction index (RII) were significantly higher than 0 under all environmental conditions, demonstrating that plant-plant interactions generated positive effects in the intercropping system. The maize yield and biomass RII were 0.029-0.095 and 0.018-0.066, respectively, which indicated that maize growth was constantly facilitated. However, the RII for grass pea yield and biomass exhibited a different trend in comparison with maize. It was higher than 0 (as the facilitated species) under low soil P and moisture conditions and transitioned to values lower than 0 (facilitator species) under high P and moisture conditions, which showed that the type and intensity of plant-plant interactions steadily shifted with the applied stressors. Direct interactions decreased the maize rhizospheric soil pH by 1.5% and 1.9% under Low-P conditions. Notably, the rhizospheric soil acid and alkaline phosphatase secretions of maize and grass pea increased by 17.4-27.4% and 15.3-27.7%, respectively, in P-deficient soils. These results show that plant-plant interactions can effectively relieve P stress by mineralizing organophosphorus in P-deficient soils. Furthermore, the above tendency became more pronounced under drought-stressed conditions. The nylon barrier partially restricted the exchange and utilization of available nutrients and decreased the total yield and biomass by 1.8-7.8% and 1.1-7.8%, respectively. The presence of a solid barrier completely restricted interspecific rhizospheric interactions and decreased the total yield and biomass by 2.1-13.8% and 1.6-15.7%, respectively. Phytate and KH2PO4 addition intensified asymmetric interspecific competition, and grass pea was consistently subjected to competitive pressures. CONCLUSION: Briefly, the tradeoff between facilitation and competition was driven by rhizospheric interactions, and the transition in the intensity and type of interaction was highly dependent on resource availability in a biologically diverse system.

The plant cuticle is required for osmotic stress regulation of abscisic acid biosynthesis and osmotic stress tolerance in Arabidopsis.

Osmotic stress activates the biosynthesis of abscisic acid (ABA). One major step in ABA biosynthesis is the carotenoid cleavage catalyzed by a 9-cis epoxycarotenoid dioxygenase (NCED). To understand the mechanism for osmotic stress activation of ABA biosynthesis, we screened for Arabidopsis thaliana mutants that failed to induce the NCED3 gene expression in response to osmotic stress treatments. The ced1 (for 9-cis epoxycarotenoid dioxygenase defective 1) mutant isolated in this study showed markedly reduced expression of NCED3 in response to osmotic stress (polyethylene glycol) treatments compared with the wild type. Other ABA biosynthesis genes are also greatly reduced in ced1 under osmotic stress. ced1 mutant plants are very sensitive to even mild osmotic stress. Map-based cloning revealed unexpectedly that CED1 encodes a putative α/ß hydrolase domain-containing protein and is allelic to the BODYGUARD gene that was recently shown to be essential for cuticle biogenesis. Further studies discovered that other cutin biosynthesis mutants are also impaired in osmotic stress induction of ABA biosynthesis genes and are sensitive to osmotic stress. Our work demonstrates that the cuticle functions not merely as a physical barrier to minimize water loss but also mediates osmotic stress signaling and tolerance by regulating ABA biosynthesis and signaling.

The efficacy of 3 root canal sealers combined with warm gutta-percha vertical compression technique in the treatment of dental pulp disease.

To investigate the efficacy of 3 root canal sealants such as AH Plus, GuttaFlow and iRoot SP combined with warm gutta-percha vertical compression technique in the treatment of dental pulp disease. This was a single-center retrospective study. 180 patients with dental pulp disease were divided into AH Plus group (n = 60), GuttaFlow group (n = 60) and iRoot SP group (n = 60) according to the different treatment methods. Patients in different groups were treated with corresponding root canal sealant combined with warm gutta-percha vertical compression technique. The quality of root canal filling, filling time, filling area ratio, the incidence of pain after operation, serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) and efficacy at 6 months after operation were compared among the 3 groups, respectively. The filling time in the GuttaFlow group and the iRoot SP group was significantly shorter than that in the AH Plus group (P < .001). There were significant differences in pain grade (P = .015) and pain rate (P = .016) among the 3 groups, and the pain rate in the GuttaFlow group and the iRoot SP group was significantly lower than that in the AH Plus group (P = .016). The time-point effect, intergroup effect and time-groups effect of serum TNF-α and IL-6 were significantly different (P < .001), and the levels of the 3 groups after treatment were significantly lower than those before treatment (P < .05), and the levels were significantly lower in the GuttaFlow group and the iRoot SP group (P < .05). There were significant differences in efficacy grading and effective rate among the 3 groups (P = .028), and the effective rate of iRoot SP group was significantly higher than that of AH Plus group (P < .05). The iRoot SP or GuttaFlow as root canal sealant combined with warm gutta-percha vertical compression technique in the treatment of dental pulp disease is better than AH Plus, and the former one can shorten the filling time, relieve the postoperative pain and improve the inflammatory response, but the long-term apical sealing effect of iRoot SP is better than GuttaFlow.

Spatial Trueness Evaluation of 3D-Printed Dental Model Made of Photopolymer Resin: Use of Special Structurized Dental Model.

(1) Background: Various 3D printers are available for dental practice; however, a comprehensive accuracy evaluation method to effectively guide practitioners is lacking. This in vitro study aimed to propose an optimized method to evaluate the spatial trueness of a 3D-printed dental model made of photopolymer resin based on a special structurized dental model, and provide the preliminary evaluation results of six 3D printers. (2) Methods: A structurized dental model comprising several geometrical configurations was designed based on dental crown and arch measurement data reported in previous studies. Ninety-six feature sizes can be directly measured on this original model with minimized manual measurement errors. Six types of photo-curing 3D printers, including Objet30 Pro using the Polyjet technique, Projet 3510 HD Plus using the Multijet technique, Perfactory DDP and DLP 800d using the DLP technique, Form2 and Form3 using the SLA technique, and each printer's respective 3D-printable dental model materials, were used to fabricate one set of physical models each. Regarding the feature sizes of the simulated dental crowns and dental arches, linear measurements were recorded. The scanned digital models were compared with the design data, and 3D form errors (including overall 3D deviation; flatness, parallelism, and perpendicularity errors) were measured. (3) Results: The lowest overall 3D deviation, flatness, parallelism, and perpendicularity errors were noted for the models printed using the Objet30 Pro (overall value: 45 µm), Form3 (0.061 ± 0.019 mm), Objet30 Pro (0.138 ± 0.068°), and Projet 3510 HD Plus (0.095 ± 0.070°), respectively. In color difference maps, different deformation patterns were observed in the printed models. The feature size proved most accurate for the Objet30 Pro fabricated models (occlusal plane error: 0.02 ± 0.36%, occlusogingival direction error: -0.06 ± 0.09%). (4) Conclusions: The authors investigated a novel evaluation approach for the spatial trueness of a 3D-printed dental model made of photopolymer resin based on a structurized dental model. This method can objectively and comprehensively evaluate the spatial trueness of 3D-printed dental models and has a good repeatability and generalizability.

Adhesive and biodegradable polymer mixture composed of high -biosafety pharmaceutical excipients as non-setting periodontal dressing.

Periodontal dressing is a surgical dressing applied to oral wounds after periodontal surgery. Currently, all commercially available setting periodontal dressings are stiff, uncomfortable, with poor aesthetics, and need to be removed at the patient's follow-up visit, which may cause secondary damage. A periodontal dressing with soft texture, biodegradable properties, and that could balance both comfort and aesthetics is urgently desired. Hence, non-setting and degradable dressings were developed using sodium carboxymethyl cellulose, Eudragit S 100 and povidone K30, which were compared with the commercial degradable dressing Reso-pac®. The mucosal adhesion of the dressings was evaluated by lap shear tests, which indicated adequate adhesion. The in vitro swelling rates of the dressings were approximately half that of Reso-pac®, which led to less saliva adsorption and better dimensional stability. The dressings also exhibited satisfactory biocompatibility according to the results of CCK-8, Live/Dead staining, hemolysis, and subcutaneous implantation assays. Moreover, the dressing promoted the healing of full-thickness mucosal wounds in the palatal gingivae of SD rats and contributed to better therapeutic effect than Reso-pac®. Considering the multiple advantages and the pure pharmaceutical excipient formula, we anticipate that this dressing could be a promising product and may enter clinical practice in the near future.

Farmers' participation into the recovery of waste agricultural plastic film: An application of the Theory of Planned Behavior.

This study aims to address the lack of relevant researches in the field of waste recycling using the Theory of Planned Behavior (TPB). A village-scale social survey was conducted to investigate the degree of farmers' participation in a waste plastic film program, i.e. Old for New in northwest China. The program required farmers to recycle plastic film residues in exchange for new films. Survey results showed that 67.5% of farmers accepted the program, yet only 14.5% of them actually participated. Logistic regression analysis was used to analyze questionnaire data and identify the factors that significantly affected farmers' recycling behavior. Principal component and weight analysis further showed that farmers' participation was mainly influenced by their attitudes (p < 0.01), with a relative weight (RW) of 46.3%. Yet, subjective norms (p < 0.1) and perceived behavior control (p < 0.1) had less effect on the degree of participation, and their RWs were 4.2% and 4.1% only, respectively. Moreover, the RW of plastic film usage characteristics and household characteristics reached up to 13.2% and 6.4%, respectively. Interestingly, environmental awareness (ß = 0.083) and compulsory environmental education (ß = 0.130) as surface factors strongly affected the farmers' adoption and response, with the RW of 25.7%. As such, the extended TPB model was established to analyze the participation behavior of farmers for stronger explanatory power. This study highlighted a promising strategy based on TPB for waste plastic film recycling and similar environmental management practices.

Poly-l-lactic acid (PLLA)/anthocyanin nanofiber color indicator film for headspace detection of low-level bacterial concentration.

Since bacterial contamination is a significant threat to humans, early detection is essential to safeguard dietary safety and physical health. Here, a nanofiber color indicator film based on poly-l-lactic acid (PLLA) as the support and anthocyanin as the indicator material was prepared by electrostatic spinning. It was found that the PLLA/0.8CY nanofiber color indicator film was hydrophobic (the water contact angle of 102.4°) and contained uniform nanofibers with an average diameter of 750 nm. In addition, the film's humidity insensitivity, reusability, color stability, and ammonia sensitivity (the limits of detection 35.39 ppm) made the film environmentally friendly and more accurate and faster for bacterial detection. The film was able to sense 102 CFU/mL of gram-positive and negative bacteria after the model strain E. coli and L. monocytogene. Thus, the PLLA/0.8CY nanofiber color indicator film was able to perform headspace nondestructive detection of low-level bacterial contamination.

Multi-responsive poly N-isopropylacrylamide/poly N-tert-butylacrylamide nanocomposite hydrogel with the ability to be adsorbed on the chitosan film as an active antibacterial material.

Nanocomposite hydrogel composed of Poly N-isopropylacrylamide (PNIPAM), poly N-tert-Butylacrylamide (PBAM) and poly acrylic acid (PAA) was synthesized by free radical polymerization, and then thymol was embedded in it, to design an active antibacterial material that could control release. The characterization of products used SEM, AFM, FTIR, Zeta sizer to analyze the sensitivity of nanoparticles to pH, temperature and salt ions, and the agar diffusion method was used to determine the antibacterial effect of the polymers. The results showed that nanoparticles had pH, temperature and salt ion responsiveness, PNIPAM/PBAM (65:35) nanoparticles loaded thymol had longer release time (more than 24 h) at lower temperature than that (around 6 h) at high temperature. In addition, the nanoparticles could also be adsorbed on the chitosan film, which makes it have a wider range of applications. All thymol-loaded nanoparticles showed antibacterial activity against both B. subtilis and E. coli, while the chitosan film adsorbed nanoparticles showed weak effect, which was related to the controlled and slow release of bacteriostatic agents. Thus, these copolymers have potential value in the development and application of bacteriostatic packaging films for food.

Enhanced oxidative depolymerization of lignin in cooperative imidazolium-based ionic liquid binary mixtures.

The aerobic oxidation of lignin model 2-phenoxyacetophenone (2-PAP) in cooperative ionic liquid mixtures (CoILs) with 1-ethyl-3-methylimidazolium acetate ([C2C1im]OAc) and 1-benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BZC1im]NTf2) was investigated. Complete degradation of 2-PAP was achieved with [C2C1im]OAc/[BZC1im]NTf2 molar ratio (RIL) of 1/1 and 1/2 at 100 °C for 2 h. The conversion and product yields from CoILs were higher than those in pure ILs, indicating the cooperative effects of [C2C1im]OAc/[BZC1im]NTf2 on cleaving aryl-ether bonds. [C2C1im]OAc promoted the catalytic cleavage of aryl-ether bonds and solvation, and [BZC1im]NTf2 induced the formation of alkyl radicals and enhanced the product selectivity. Accordingly, the highest conversion of alkali lignin (79.8%) was obtained with RIL of 5/1 at 100 °C for 2 h, and phenol monomers (306 mg/g) were selectively produced. The CoILs exhibited good catalytic capacities for oxidative depolymerization of lignin, which strongly depends on the changes in intermolecular interactions and structural organization with varying RIL.

1-Ethyl-3-methylimidazolium acetate ionic liquid as simple and efficient catalytic system for the oxidative depolymerization of alkali lignin.

The oxidative depolymerization of alkali lignin (AL) in 1-ethyl-3-methylimidazolium acetate ([C2C1im]OAc) system without additional catalyst was investigated under mild conditions (initial O2 pressure of 1.5 MPa, 80 °C-100 °C). Compared with other ionic liquids (ILs), the cooperation of imidazolium cation and acetate anion successfully enhanced AL conversion. Among the investigated imidazolium acetate ILs with ethyl- to octyl-side chains, [C2C1im]OAc presented the best catalytic capacity for AL oxidative depolymerization. Adding an appropriate amount of water to [C2C1im]OAc can further improve the reaction efficiency. In the [C2C1im]OAc system with the addition of 0.10-0.25 mL of water, approximately 77 wt% AL was depolymerized into small molecule soluble products at 100 °C for 2 h. The extracted oil was composed mainly of phenolic derived compounds. With the use of the [C2C1im]OAc-based system, the specific inter-unit linkages of lignin were broken down, and residual lignin with low molecular weight and narrow polydispersity index (1.88-1.96) was obtained. Compared with that in AL conversion with fresh [C2C1im]OAc, only a minimal decrease (~3.2%) was observed with the recovered IL until the fifth cycle. These findings revealed that [C2C1im]OAc-based system is a simple and efficient catalytic system for lignin oxidative depolymerization.

Electrically Activated Soft Robots: Speed Up by Rolling.

Soft robots show excellent body compliance, adaptability, and mobility when coping with unstructured environments and human-robot interactions. However, the moving speed for soft locomotion robots is far from that of their rigid partners. Rolling locomotion can provide a promising solution for developing high-speed robots. Based on different rolling mechanisms, three rolling soft robot (RSR) prototypes with advantages of simplicity, lightweight, fast rolling speed, good compliance, and shock resistance are fabricated by using dielectric elastomer actuators. The experimental results demonstrate that the impulse-based and gravity-based RSRs can move both stably and continuously on the ground with a maximum speed higher than 1 blps (body length per second). The ballistic RSR exhibits a high rolling speed of ∼4.59 blps. And during its accelerating rolling process, the instantaneous rolling speed of the robot prototype reaches about 0.65 m/s (13.21 blps), which is much faster than most of the previously reported locomotion robots driven by soft responsive materials. The structure design and implementation methods based on different rolling mechanisms presented can provide guidance and inspiration for creating new, fast-moving, and hybrid mobility soft robots.

Rare Occurrence of Acute Hematogenous Periprosthetic Joint Infection Due to Fusobacterium Nucleatum in the Background of a Dental Procedure: A Case Report.

OBJECTIVE: Fusobacterium nucleatum is an anaerobic gram-negative bacilli that is one of the oral and other mucosal surface microbiota. It involves a wide range of human diseases and was first found in periodontal diseases, but reports of bone-related infections caused by F. nucleatum are rare, especially periprosthetic joint infections (PJI). METHODS: Here, we present the first case of acute hematogenous PJI of the hip joint caused by F. nucleatum, and debridement, antibiotics, and implant retention (DAIR) was performed. RESULTS: The patient was successfully treated with DAIR, identification of isolates by metagenomics next-generation sequencing was confirmed by polymerase chain reaction. CONCLUSIONS: For stable acute hematogenous PJI after hip replacement, quick and accurate diagnosis, the identification of pathogenic microorganisms, and the use of DAIR combined with sufficient sensitive antibiotics have a certain clinical effect and can achieve the purpose of both preserving the prosthesis and infection control.

[ANTIBIOTIC-IMPREGNATED ARTICULAR CEMENT SPACER FOR TREATMENT OF PERIPROSTHETIC JOINT INFECTION].

OBJECTIVE: To investigate the current problems and corresponding solutions regarding the use of antibiotic-impregnated cement spacer for the treatment of periprosthetic joint infection (PJI). METHODS: A retrospective analysis was made on the clinical data of 27 patients with PJI who underwent two-stage revision with antibiotic-impregnated cement spacer between January 2001 and January 2013. There were 12 males and 15 females, with an average age of 62.7 years (range, 25-81 years). All arthroplasties were unilateral, including 19 hip PJI and 8 knee PJI. The mean duration from primary arthroplasty to PJI was 25 months (range, 3-252 months). After infection was controlled with the antibiotic-impregnated cement spacer combined with systematic antibiotics treatment, two-stage revision was performed. The effectiveness was evaluated. Results One patient died of myocardial infarction at 2 days after surgery. Infection was controlled, and two-stage revision was successfully performed in 19 patients; deep venous thrombosis occurred in 1 of 3 patients who experienced hip spacer fractures, which was cured after conservative management. The spacers were removed and bacteria-sensitive antibiotics was used because of recurrent infections after the first-stage surgery in 7 patients; 3 patients gave up treatment because infection was not controlled, 4 patients received revision after infection was controlled. Twenty-three patients were followed up 1-5 years (mean, 2.3 years). The average Harris hip score and KSS score at 1 years after revision were significantly improved when compared with preoperative ones (P<0.05). In the 8 patients with gram-negative or fungus infection, 7 were found to have recurrent infection after the first-stage surgery; in the 12 patients with gram-positive infection, no recurrent infection was found. Failed treatment was observed in 1 patient with gram-positive and gram-negative infections and 2 with fungus infection, respectively. CONCLUSION: Antibiotic- impregnated cement spacer has a satisfactory effectiveness for PJI. However, complication of spacer fracture should be noted, especially hip spacers. If the pathogen is gram-negative bacteria or fungus, the implanted spacer may increase the possibility of recurrent infection.

Paper-Based Active Tactile Sensor Array.

A paper-based active tactile sensor -array (PATSA) with a dynamic sensitivity of 0.35 V N(-1) is demonstrated. The pixel position of the PATSA can be routed by analyzing the real-time recording voltages in the pressing process. The PATSA performance, which remains functional when removing partial areas, reveals that the device has a potential application to customized electronic skins.