Hydrogels for Oral Tissue Engineering: Challenges and Opportunities.

Oral health is crucial to daily life, yet many people worldwide suffer from oral diseases. With the development of oral tissue engineering, there is a growing demand for dental biomaterials. Addressing oral diseases often requires a two-fold approach: fighting bacterial infections and promoting tissue growth. Hydrogels are promising tissue engineering biomaterials that show great potential for oral tissue regeneration and drug delivery. In this review, we present a classification of hydrogels commonly used in dental research, including natural and synthetic hydrogels. Furthermore, recent applications of these hydrogels in endodontic restorations, periodontal tissues, mandibular and oral soft tissue restorations, and related clinical studies are also discussed, including various antimicrobial and tissue growth promotion strategies used in the dental applications of hydrogels. While hydrogels have been increasingly studied in oral tissue engineering, there are still some challenges that need to be addressed for satisfactory clinical outcomes. This paper summarizes the current issues in the abovementioned application areas and discusses possible future developments.

Research Progress in the Synthesis of Carbon Dots and Their Application in Food Analysis.

Food safety is connected to public health, making it crucial to protecting people's health. Food analysis and detection can assure food quality and effectively reduce the entry of harmful foods into the market. Carbon dots (CDs) are an excellent choice for food analysis and detection attributable to their advantages of good optical properties, water solubility, high chemical stability, easy functionalization, excellent bleaching resistance, low toxicity, and good biocompatibility. This paper focuses on the optical properties, synthesis methods, and applications of CDs in food analysis and detection, including the recent advances in food nutritional composition analysis and food quality detection, such as food additives, heavy metal ions, foodborne pathogens, harmful organic pollutants, and pH value. Moreover, this review also discusses the potentially toxic effects, current challenges, and prospects of CDs in basic research and applications. We hope that this review can provide valuable information to lay a foundation for subsequent research on CDs and promote the exploration of CDs-based sensing for future food detection.

In situ-prepared poly(ether-ester)-based gel polymer electrolytes for high-performance lithium metal batteries.

Batteries based on an in situ-polymerized amorphous cross-linked poly(ether-ester) GPE exhibit high performance, which is attributed to the synergistic effect of the ether and ester segments of the GPE and the in situ-generated polymer electrolytes.

Visible-Light-Driven Zr-MOF/BiOBr Heterojunction for the Efficient Synchronous Removal of Hexavalent Chromium and Rhodamine B from Wastewater.

With the rapid industrial development, the coexistence of multiple pollutants in wastewater has become a common phenomenon. Thus, developing highly efficient decontamination methods is imperative. In this work, a string of UiO-66-NH2/BiOBr heterojunctions with varying ratios of BiOBr were prepared and applied to remove hexavalent chromium Cr(VI) and rhodamine B (RhB). The possible growth process of BiOBr nanosheets on UiO-66-NH2, removal activity of contaminants, and photocatalysis mechanism were investigated. When the mass ratio of UiO-66-NH2 to BiOBr reaches 1:0.75, the heterojunction (NB-75) shows optimal photocatalytic activity. After 30 min of adsorption, the total removal rates of Cr(VI) (50 mg/L) and RhB (10 mg/L) over NB-75 (0.25 g/L) reaches 96.7% within 120 min of illumination and 98.9% within 80 min of illumination, respectively. For the removal process, there are two factors. The first is the high adsorption capacity for RhB and Cr(VI) owing to the high porosity of UiO-66-NH2 and interlayer surface positive charge of BiOBr. The second is the improved visible-light photocatalytic performance of the UiO-66-NH2/BiOBr heterojunction via rapid separation of photoinduced carriers. In addition, the active species capture study reveals that the electrons (e-) and the superoxide radicals (•O2 -) play key roles in Cr(VI) reduction, while the holes (h+) are major reactive groups participating in the degradation of RhB. This work demonstrated a kind of promising MOF-based photocatalysis material for eliminating Cr(VI) and RhB simultaneously.

Directional Migration and Distribution of Magnetic Microparticles in Polypropylene-Matrix Magnetic Composites Molded by an Injection Molding Assisted by External Magnetic Field.

Surface-functionalized polymer composites with spherical particles as fillers offer great qualities and have been widely employed in applications of sensors, pharmaceutical industries, anti-icing, and flexible electromagnetic interference shielding. The directional migration and dispersion theory of magnetic microparticles in polypropylene (PP)-matrix magnetic composites must be studied to better acquire the functional surface with remarkable features. In this work, a novel simulation model based on multi-physical field coupling was suggested to analyze the directed migration and distribution of magnetic ferroferric oxide (Fe3O4) particles in injection molding assisted by an external magnetic field using COMSOL Multiphysics® software. To accurately introduce rheological phenomena of polymer melt into the simulation model, the Carreau model was used. Particle size, magnetic field intensity, melt viscosity, and other parameters impacting particle directional motion were discussed in depth. The directional distribution of particles in the simulation model was properly assessed and confirmed by experiment results. This model provides theoretical support for the control, optimization, and investigation of the injection-molding process control of surface-functionalized polymer composites.

Tough, Anti-Swelling Supramolecular Hydrogels Mediated by Surfactant-Polymer Interactions for Underwater Sensors.

It is a great challenge for traditional hydrogel-based sensors to be effective underwater due to unsatisfactory water resistance and insufficient wet adhesion. Herein, a tough supramolecular hydrogel aiming at underwater sensing is prepared by the modification of hydrophilic poly(acrylic acid) (PAA) with a small amount of hydrophobic lauryl methacrylate (LMA) in the presence of high concentrations of the cationic surfactant cetyltrimethylammonium bromide (CTAB). Owing to the synergistic effects of the electrostatic interactions and hydrophobic associations of CTAB with the P(AA-co-LMA) copolymer, the hydrogel with a water content of approximately 58.5 wt % demonstrates outstanding anti-swelling feature, superior tensile strength (≈1.6 MPa), large stretchability (>900%), rapid room-temperature self-recovery (≈3 min at 100% strain), and robust wet adhesion to diverse substrates. Moreover, the strain sensor based on the hydrogel displays keen sensitivity in a sensing range of 0-900% (gauge factor is 0.42, 3.44, 5.44, and 7.39 in the strain range of 0-100, 100-300, 300-500, and 500-900%, respectively) and pronounced stability both in air and underwater. Additionally, the hydrogel can be easily recycled by dissolving in anhydrous ethanol. This work provides a facile strategy to fabricate eco-friendly, tough supramolecular hydrogels for underwater sensing.

Fabrication of Biodegradable and Biocompatible Functional Polymers for Anti-Infection and Augmenting Wound Repair.

The problem of bacteria-induced infections threatens the lives of many patients. Meanwhile, the misuse of antibiotics has led to a significant increase in bacterial resistance. There are two main ways to alleviate the issue: one is to introduce antimicrobial agents to medical devices to get local drug releasing and alleviating systemic toxicity and resistance, and the other is to develop new antimicrobial methods to kill bacteria. New antimicrobial methods include cationic polymers, metal ions, hydrophobic structures to prevent bacterial adhesion, photothermal sterilization, new biocides, etc. Biodegradable biocompatible synthetic polymers have been widely used in the medical field. They are often used in tissue engineering scaffolds as well as wound dressings, where bacterial infections in these medical devices can be serious or even fatal. However, such materials usually do not have inherent antimicrobial properties. They can be used as carriers for drug delivery or compounded with other antimicrobial materials to achieve antimicrobial effects. This review focuses on the antimicrobial behavior, preparation methods, and biocompatibility testing of biodegradable biocompatible synthetic polymers. Degradable biocompatible natural polymers with antimicrobial properties are also briefly described. Finally, the medical applications of these polymeric materials are presented.

Combined Approach of Compression Molding and Magnetic Attraction to Micropatterning of Magnetic Polydimethylsiloxane Composite Surfaces with Excellent Anti-Icing/Deicing Performance.

The accumulation of ice and contaminants on the surface of composite insulators will cause high energy consumption or even major hazards to power systems. In this work, the polydimethylsiloxane (PDMS) silicone rubber was modified by surface micropatterning and material compositing. Highly crosslinked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) (PZS) was used to directly coat ferroferric oxide (Fe3O4) nanoparticles. The obtained core-shell Fe3O4@PZS microspheres were loaded with carbon nanotubes (CNTs) to get CNTs/Fe3O4@PZS as the photothermal magnetic filler. The PDMS/CNTs/Fe3O4@PZS surfaces with micronscale truncated cones were prepared via a combined method of compression molding and magnetic attraction. The 1H,1H,2H,2H-perfluorodecyltrichlorosilane-coated template and magnetic field can increase the height of the microstructure to ∼76 µm and maintain the contact angle of microstructured PDMS/CNTs/Fe3O4@PZS surfaces at a high level (∼152°). Compared with the flat PDMS surface, the micronscale truncated cones extend the freezing time from 4.5 to 11.5 min and also undermine the ice adhesion strength from ∼25 to ∼17 kPa for the microstructured PDMS/CNTs/Fe3O4@PZS surface. The temperature of the PDMS/CNTs/Fe3O4@PZS surface molded with magnetic attraction increases linearly with time and the internal magnetic fillers and achieves 280 °C in 10 s. The efficiency of temperature rise is increased by ∼46%, and hence the entire frozen water droplet can melt within 20 s. The strategy combining active deicing with passive anti-icing undoubtedly promotes the development of high efficiency anti-icing materials and can be applied on insulators to prevent icing flashover.

Psychological impact of COVID-19 pandemic on healthcare workers in China Xi'an central hospital.

OBJECTIVE: COVID-19 significantly altered our routine, lifestyle, and stress level across the globe. This study investigated the psychological impact of COVID-19 on healthcare workers in China Xi'an Center hospital. METHODS: A modified online questionnaire of Psychological Status and the General Health Questionnaire (GHQ-12) was provided to 1,967 healthcare workers during the COVID-19 pandemic. Participation was voluntary, and the responses were anonymous. The survey lasted for 2 weeks, and the GHQ-12 was completed every other day. The data were collected automatically and electronically and then statistically analyzed. RESULTS: The 431 (21.9%) responders included 214 nurses (49.7%), 146 clinicians (33.9%), 29 pharmacists (6.7%), 15 medical technicians (3.5%), 17 administrative staff (3.9%), and 10 other departments (2.3%). Of these, 46.2% had 10 years of work experiences or more and 78.2% were married. Work experience increased emotional stress as 23% of participants with 10 years or more of experience exhibited higher stress compared to those with fewer than 3 years of work experience (7.5%). Moreover, 33.3% of participants who worked in or were exposed to the affected areas of the pandemic experienced psychological stress. Overall, this study identified four factors that were significantly associated with psychological stress: (a) work experience (OR 2.99; 95% CI: 1.06 to 8.41); (b) change in job position (OR 1.99; 95% CI: 1.10 to 3.59); (c) change in lifestyle (OR 4.06; 95% CI: 1.81 to 9.10); and (d) need for psychological counseling (OR 3.07; 95% CI: 1.62 to 5.82). CONCLUSIONS: The COVID-19 pandemic has increased psychological stress among healthcare workers with 10 years or more work experiences and who recently experienced a career position change.

Effects of Coated Separator Surface Morphology on Electrolyte Interfacial Wettability and Corresponding Li-Ion Battery Performance.

In order to study the effect of interfacial wettability of separator on electrochemical properties for lithium-ion batteries, two different kinds of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) solution are prepared and used to coat onto a polypropylene (PP) microporous membrane. It is found that the cell performance of a coated separator using aqueous slurry (WPS) is better than that of the coated separator using acetone (APS) as the solvent. The separator with flat and pyknotic surface (PP and APS) has a strong polar action with the electrolyte, where the polar part is more than 80%. To the contrary, the WPS has a roughness surface and when the PVDF-HFP particles accumulate loose, it makes the apolar part plays a dominate role in surface free energy; the dispersive energy reaches to 40.17 mJ m-2. The WPS has the lowest immersion free energy, 31.9 mJ m-2 with the electrolyte, and this will accelerate electrolyte infiltration to the separator. The loose particle accumulation also increases the electrolyte weight uptake and interfacial wettability velocity, which plays a crucial role in improving the cell performance such as the ionic conductivity, discharge capacity and the C-rate capability.

Studying the Ring-Opening Polymerization of 1,5-Dioxepan-2-one with Organocatalysts.

Three different organocatalysts, namely, 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris (dimethylamino) phosphoranylidenamino]-2Λ5,4Λ5-catenadi(phosphazene) (t-BuP4), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), have been used as 1,5-dioxepan-2-one (DXO) ring-opening polymerization (ROP) catalysts at varied reaction conditions. 1H NMR spectra, size exclusion chromatography (SEC) characterizations, and kinetic studies prove that the (co)polymerizations are proceeded in a controlled manner with the three organocatalysts. It is deduced that t-BuP4 and DBU catalysts are in an initiator/chain end activated ROP mechanism and TBD is in a nucleophilic ROP mechanism.

Preparation and hemostatic property of low molecular weight silk fibroin.

Effective hemorrhage control becomes increasingly significant in today's military and civilian trauma, while the topical hemostats currently available in market still have various disadvantages. In this study, three low molecular weight silk fibroins (LMSF) were prepared through hydrolysis of silk fibroin in a ternary solvent system of CaCl2/H2O/EtOH solution at different hydrolysis temperatures. Fourier transform infrared spectroscopy analysis showed that the content of ß sheet structure in the LMSF decreased with the increase in hydrolysis temperature. The results of thromboelastographic and activated partial thromboplastin time methods showed that the LMSF hydrolyzed at 50 °C can significantly strengthen the coagulation in blood and activate the intrinsic pathway of coagulation cascade. In the murine hepatic injury model, the LMSF hydrolyzed at 50 °C can promote the blood clotting and decrease the blood loss and bleeding time. Based on these results, it can be suggested that the developed LMSF has the excellent hemostatic effect and may be a promising material in clinical hemostatic application.