Effects of minimally invasive endodontic access cavity in molar teeth on polymerization, porosity and fracture resistance.

Minimally invasive access cavities have been proposed in the last decade to reduce tooth tissue loss during endodontic treatment and mitigate compromised fracture resistance of endodontically treated teeth. Fracture resistance of molars with different types of access cavity design may be affected by restorative materials and aging. Insufficient literature data exist on the effect of cavity design and type of restorative materials on restorative aspects such as material adaptation or photo-polymerization in restricted access cavities. This study analyses quality of polymerization, material adaptation and fracture resistance of molars with different types of access cavities restored with glass-ionomer, high-viscosity fiber-reinforced bulk-fill and nanofilled resin composite. Plastic molar teeth with truss (TREC) and traditional endodontic access cavity (TEC) were restored with nanofilled composite (Filtek Supreme), glass-ionomer Fuji IX and Filtek or fiber-reinforced everX Posterior and Filtek. Porosity was determined using microcomputer tomography and the degree of conversion of resin-based materals using micro-Raman spectroscopy. Human molars prepared and restored in the same way were used for fracture resistance testing at baseline and after thermocycling. The results demonstrate that high-viscosity fiber-reinforced composite was difficult to adapt in TREC cavity leading to greater porosity than Filtek or Fuji. TREC design did not affect composite polymerization and led to higher fracture resistance of restored molars compared to TEC but also more unrestorable fractures.

Molecularly Imprinted Microspheres in Active Compound Separation from Natural Product.

Molecularly Imprinted Microspheres (MIMs) or Microsphere Molecularly Imprinted Polymers represent an innovative design for the selective extraction of active compounds from natural products, showcasing effectiveness and cost-efficiency. MIMs, crosslinked polymers with specific binding sites for template molecules, overcome irregularities observed in traditional Molecularly Imprinted Polymers (MIPs). Their adaptability to the shape and size of target molecules allows for the capture of compounds from complex mixtures. This review article delves into exploring the potential practical applications of MIMs, particularly in the extraction of active compounds from natural products. Additionally, it provides insights into the broader development of MIM technology for the purification of active compounds. The synthesis of MIMs encompasses various methods, including precipitation polymerization, suspension polymerization, Pickering emulsion polymerization, and Controlled/Living Radical Precipitation Polymerization. These methods enable the formation of MIPs with controlled particle sizes suitable for diverse analytical applications. Control over the template-to-monomer ratio, solvent type, reaction temperature, and polymerization time is crucial to ensure the successful synthesis of MIPs effective in isolating active compounds from natural products. MIMs have been utilized to isolate various active compounds from natural products, such as aristolochic acids from Aristolochia manshuriensis and flavonoids from Rhododendron species, among others. Based on the review, suspension polymerization deposition, which is one of the techniques used in creating MIPs, can be classified under the MIM method. This is due to its ability to produce polymers that are more homogeneous and exhibit better selectivity compared to traditional MIP techniques. Additionally, this method can achieve recovery rates ranging from 94.91% to 113.53% and purities between 86.3% and 122%. The suspension polymerization process is relatively straightforward, allowing for the effective control of viscosity and temperature. Moreover, it is cost-effective as it utilizes water as the solvent.

Impact of a poly(ethylene glycol) corona block on drug encapsulation during polymerization induced self-assembly.

Polymerization induced self-assembly (PISA) provides a facile platform for encapsulating therapeutics within block copolymer nanoparticles. Performing PISA in the presence of a hydrophobic drug alters both the nanoparticle shape and encapsulation efficiency. While previous studies primarily examined the interactions between the drug and hydrophobic core block, this work explores the impact of the hydrophilic corona block on encapsulation. Poly(ethylene glycol) (PEG) and poly(2-hydroxypropyl methacrylate) (PHPMA) are used as the model corona and core blocks, respectively, and phenylacetic acid (PA) is employed as the model drug. Attachment of a dithiobenzoate end group to the PEG homopolymer - transforming it into a macroscopic reversible addition-fragmentation chain transfer agent - causes the polymer to form a small number of nanoscopic aggregates in solution. Adding PA to the PEG solution encourages further aggregation and macroscopic phase separation. During the PISA of PEG-PHPMA block copolymers, inclusion of PA in the reaction mixture promotes faster nucleation of spherical micelles. Although increasing the targeted PA loading from 0 to 20 mg mL-1 does not affect the micelle size or shape, it alters the drug spatial distribution within the PISA microenvironment. PA partitions into either PEG-PHPMA micelles, deuterium oxide, or other polymeric species - including PEG aggregates and unimer chains. Increasing the targeted PA loading changes the fraction of drug within each encapsulation site. This work indicates that the corona block plays a critical role in dictating drug encapsulation during PISA.

In Situ Polymerization for Manufacture of Multifunctional Delivery Systems for Transcellular Delivery of Nucleic Acids.

Electrostatic self-assembly between negatively charged nucleic acids and cationic materials is the basis for the formulation of the delivery systems. Nevertheless, structural disintegration occurs because their colloidal stabilities are frequently insufficient in a hostile biological environment. To overcome the sequential biological barriers encountered during transcellular gene delivery, we attempted to use in situ polymerization onto plasmid DNA (pDNA) with a variety of functional monomers, including N-(3-aminopropyl)methacrylate, (aminopropyl)methacrylamide hydrochloride, 1-vinylimidazole, and 2-methacryloyloxyethylphosphorylcholine and N,N'-bis(acryloyl) cystamine. The covalently linked monomers could polymerize into a network structure on top of pDNA, providing excellent structural stability. Additionally, the significant proton buffering capacity of 1-vinylimidazole is expected to aid in the release of pDNA payloads from acidic and digestive endolysosomes. In addition, the redox-mediated cleavage of the disulfide bond in N,N'-bis(acryloyl)cystamine allows for the selective cleavage of the covalently linked network in the cytosolic microenvironment. This is due to the high intracellular level of glutathione, which promotes the liberation of pDNA payloads in the cell interiors. The proposed polymerization strategies resulted in well-defined nanoscale pDNA delivery systems. Excellent colloidal stabilities were observed, even when incubated in the presence of high concentrations of heparin (10 mg/mL). In contrast, the release of pDNA was confirmed upon incubation in the presence of glutathione, mimicking the intracellular microenvironment. Cell transfection experiments verified their efficient cellular uptake and gene expression activities in the hard-transfected MCF-7 cells. Hence, the polymerization strategy used in the fabrication of covalently linked nonviral gene delivery systems shows promise in creating high-performance gene delivery systems with diverse functions. This could open new avenues in cellular microenvironment engineering.

Fabrication and properties of temperature-responsive imprinted sensors based on fluorescently labeled yeast cells via MVL ATRP.

Temperature-responsive yeast cell-imprinted sensors (CIPs/AuNPs/Ti3C2Tx/AuNPs/Au) were prepared based on fluorescein isothiocyanate labeled yeast cells (FITC-yeast) via metal-free visible-light-induced atom transfer radical polymerization (MVL ATRP). Here, N-isopropyl acrylamide (NIPAM) was used as a temperature-responsive functional monomer, α-methacrylic acid (MAA) was chosen as an auxiliary functional monomer, N,N'-methylene bisacrylamide (MBA) was used as a cross-linker, and FITC-yeast was selected as both a template and photocatalyst. Under the optimal conditions, the detection range of the yeast cell-imprinted sensor toward yeast cells was 1.0 × 102 to 1.0 × 109 cells per mL, and the detection limit was 11 cells per mL (S/N = 3), with a linear equation of ΔI (µA) = 8.44 log[C (cells per mL)] + 7.62 (R2 = 0.993). The sensor showed good selective recognition in the presence of interfering substances such as autolyzed yeast cells (AY), dead yeast cells (DY), human mammary epithelial cells (MCF-10A), human breast cancer cells (MCF-7) and Escherichia coli (EC). The sensor also had good consistency and reproducibility. Finally, spiked recovery experiments were performed to investigate the recognition of yeast cells in the actual sample using the yeast cell-imprinted sensor. The spiked recoveries were all in the range of 98.5-108.0%, and the RSD values were all less than 4%, indicating that the sensor had good application prospects.

Physicochemical properties of flowable composites using isobornyl methacrylate as diluent monomer.

OBJECTIVE: this study sought to evaluate the effect of isobornyl methacrylate (IBOMA) as a diluent monomer on the physicochemical properties of experimental flowable resin composites. METHODOLOGY: the organic resin matrix of a modal flowable resin composite was formulated with 50 wt.% of bisphenol-A-glycidyl methacrylate (Bis-GMA) and 50 wt.% of a diluent monomer, in which IBOMA was used as a combining or substituent diluent monomer to triethylene glycol dimethacrylate (TEGDMA). The resin matrices were filled with 55 wt.% particles, of which 10 wt.% was 0.05-µm fumed silica, and 45 wt.% was 0.7-µm BaBSiO2 glass. Polymerization shrinkage stress (PSS; n=10), degree of conversion (DC; n=3), maximum rate of polymerization (Rpmax; n=3), film thickness (FT; n=10), sorption (Wsp; n=10), solubility (Wsl; n=10), flexural strength (FS; n=10), flexural modulus (FM; n=10), Knoop microhardness (KH; n=10), and microhardness reduction after chemical softening (HR; n=10) were evaluated. Data were analyzed using one-way ANOVA, followed by Tukey's test (α=0.05; ß=0.2). RESULTS: the results showed that the substitution or addition of IBOMA reduced FT (p=0.001), PSS (p=0.013), Rpmax (p=0.001), DC (p=0.001), FM (p=0.006) Wsp (p=0.032), and Wsl (p=0.021). However, when used as a complete substituent, IBOMA demonstrated significantly lower FS (p=0.017) and KH (p=0.008), while TEGDMA demonstrated significantly lower HR (p=0.022). CONCLUSION: the flowable composite containing IBOMA combined with TEGDMA showed no effect in KH and FS and effectively reduced the PSS, RP, FT, Wsp, and Wsl. However, it showed a reduction in DC, FS, and an increase in HR.

Modular Structure and Polymerization Status of GABAA Receptors Illustrated with EM Analysis and AlphaFold2 Prediction.

Type-A γ-aminobutyric acid (GABAA) receptors are channel proteins crucial to mediating neuronal balance in the central nervous system (CNS). The structure of GABAA receptors allows for multiple binding sites and is key to drug development. Yet the formation mechanism of the receptor's distinctive pentameric structure is still unknown. This study aims to investigate the role of three predominant subunits of the human GABAA receptor in the formation of protein pentamers. Through purifying and refolding the protein fragments of the GABAA receptor α1, ß2, and γ2 subunits, the particle structures were visualised with negative staining electron microscopy (EM). To aid the analysis, AlphaFold2 was used to compare the structures. Results show that α1 and ß2 subunit fragments successfully formed homo-oligomers, particularly homopentameric structures, while the predominant heteropentameric GABAA receptor was also replicated through the combination of the three subunits. However, homopentameric structures were not observed with the γ2 subunit proteins. A comparison of the AlphaFold2 predictions and the previously obtained cryo-EM structures presents new insights into the subunits' modular structure and polymerization status. By performing experimental and computational studies, a deeper understanding of the complex structure of GABAA receptors is provided. Hopefully, this study can pave the way to developing novel therapeutics for neuropsychiatric diseases.

Selective mycobacterial capture with ultraviolet-polymerized poly-dimethyldiallyl chloride functionalized surfaces.

Tuberculosis (TB) is the top cause of death from a single infectious pathogen after COVID-19. Despite molecular diagnostic advances, two-thirds of the 10 million annual TB cases are still diagnosed using direct smear microscopy which has ~50% sensitivity. To increase the analytical performance of smear microscopy, we developed and characterized a novel polymer (Polydiallyldimethylammonium chloride [PDADMAC]) engraftment on inexpensive polystyrene (PS) specifically functionalized for mycobacterial capture. Engraftment is achieved via UV photopolymerization of DADMAC monomer on plasma-activated PS. The platform was tested on sputum from presumptive TB cases in Kampala, Uganda (n = 50), with an increased overall sensitivity of 81.8% (27/33) vs. fluorescent smear microscopy 57% (19/33) compared to a molecular (Cepheid GeneXpert MTB/RIF) gold standard. Frugal smear diagnostic innovation that is rapid and does not require dedicated instrumentation may offer an important solution to bridge the TB diagnostic gap.

Changes in the surface texture of pre-polymerized acrylic resin pediatric crowns following acidulated phosphate fluoride application.

This study aimed to investigate the effect of acidulated phosphate fluoride (APF) application on filler-free polymethyl methacrylate (PMMA)-based resin blocks for computer-aided design/computer-aided manufacturing (CAD-CAM), focusing on their use in pediatric crowns. Three types of PMMA-based blocks for CAD-CAM were evaluated, and a composite resin block for CAD-CAM was used as a control. Statistical analysis (p<0.05) of the data revealed that all PMMA-based blocks showed significantly higher gloss levels than the composite resin blocks. Two PMMA-based blocks also demonstrated significantly lower Ra and Sa values. SEM images showed no irregular changes in the surface properties of the PMMA-based blocks compared to those of the composite resin block. These results are significant in meeting the increasing demand for esthetic restorative treatments in pediatrics, where APF is commonly used for caries prevention. PMMA-based resin blocks for CAD-CAM are an effective alternative to prevent esthetic degradation from gloss reduction and plaque accumulation.

Integrative experimental and computational analysis of the impact of KGM's polymerization degree on wheat starch's pasting and retrogradation characteristics.

This study investigated the influence of Konjac Glucomannan (KGM) with varying degrees of polymerization (DKGMx) on the gelatinization and retrogradation characteristics of wheat starch, providing new insights into starch-polysaccharide interactions. This research uniquely focuses on the effects of DKGMx, utilizing multidisciplinary approaches including Rapid Visco Analysis (RVA), Differential Scanning Calorimetry (DSC), rheological testing, Low-Field Nuclear Magnetic Resonance (LF-NMR), and molecular simulations to assess the effects of DKGMx on gelatinization temperature, viscosity, structural changes post-retrogradation, and molecular interactions. Our findings revealed that higher degrees of polymerization (DP) of DKGMx significantly enhanced starch's pasting viscosity and stability, whereas lower DP reduced viscosity and interfered with retrogradation. High DP DKGMx promoted retrogradation by modifying moisture distribution. Molecular simulations revealed the interplay between low DP DKGMx and starch molecules. These interactions, characterized by increased hydrogen bonds and tighter binding to more starch chains, inhibited starch molecular rearrangement. Specifically, low DP DKGMx established a dense hydrogen bond network with starch, significantly restricting molecular mobility and rearrangement. This study provides new insights into the role of the DP of DKGMx in modulating wheat starch's properties, offering valuable implications for the functional improvement of starch-based foods and advancing starch science.

Klebsiella LPS O1-antigen prevents complement-mediated killing by inhibiting C9 polymerization.

The Gram-negative bacterium Klebsiella pneumoniae is an important human pathogen. Its treatment has been complicated by the emergence of multi-drug resistant strains. The human complement system is an important part of our innate immune response that can directly kill Gram-negative bacteria by assembling membrane attack complex (MAC) pores into the bacterial outer membrane. To resist this attack, Gram-negative bacteria can modify their lipopolysaccharide (LPS). Especially the decoration of the LPS outer core with the O-antigen polysaccharide has been linked to increased bacterial survival in serum, but not studied in detail. In this study, we characterized various clinical Klebsiella pneumoniae isolates and show that expression of the LPS O1-antigen correlates with resistance to complement-mediated killing. Mechanistic data reveal that the O1-antigen does not inhibit C3b deposition and C5 conversion. In contrast, we see more efficient formation of C5a, and deposition of C6 and C9 when an O-antigen is present. Further downstream analyses revealed that the O1-antigen prevents correct insertion and polymerization of the final MAC component C9 into the bacterial membrane. Altogether, we show that the LPS O1-antigen is a key determining factor for complement resistance by K. pneumoniae and provide insights into the molecular basis of O1-mediated MAC evasion.

Unveiling the Potential of Surface Polymerized Drug Nanocrystals in Targeted Delivery.

Nanocrystals (NCs) have entirely changed the panorama of hydrophobic drug delivery, showing improved biopharmaceutical performance through multiple administration routes. NCs are potential highly loaded nanovectors due to their pure drug composition, standing out from conventional polymers and lipid nanoparticles that have limited drug-loading capacity. However, research in this area is limited. This study introduces the concept of surface modification of drug NCs through single-layer poly(ethylene glycol) (PEG) polymerization as an innovative strategy to boost targeting efficiency. The postpolymerization analysis revealed size and composition alterations, indicating successful surface engineering of NCs of the model drug curcumin of approximately 200 nm. Interestingly, mucosal tissue penetration analysis showed enhanced entry for fully coated and low cross-linked (LCS) PEG NCs, with an increase of 15 µg/cm2 compared to the control NCs. In addition, we found that polymer chemistry variations on the NCs' surface notably impacted mucin binding, with those armored with LCS PEG showing the most significant reduction in interaction with this glycoprotein. We validated this strategy in an in vitro nose-to-brain model, with all of the NCs exhibiting a promising ability to cross a tight monolayer. Furthermore, the metabolic and pro-inflammatory activity revealed clear indications that, despite surface modifications, the efficacy of curcumin remains unaffected. These findings highlight the potential of surface PEGylated NCs in targeted drug delivery. Altogether, this work sets the baseline for further exploration and optimization of surface polymerized NCs for enhanced drug delivery applications, promising more efficient treatments for specific disorders and conditions requiring active targeting.

Comparison of degree of conversion performance of bulk-fill resin composites: A systematic review and network meta-analysis of in vitro studies.

OBJECTIVES: To systematically compile data on the degree of conversion (DC) for bulk-fill composites using a network meta-analysis. METHODS: A systematic search for in vitro studies of DC of bulk-fill composites was performed in PubMed, Web of Science, Scopus, and Open Grey. Risk of bias within studies and due to missing evidence was assessed using the Joanna Briggs Institute scoring system and ROB-MEN tool, respectively. The primary outcome was the DC of bulk-fill composites. Surface Under the Cumulative Ranking curve (SUCRA) was used to rank relative performance. Inconsistencies in the model were investigated to ensure its validity and the level of confidence in the network meta-analysis (CINeMA) was assessed. RESULTS: A total of 28 studies were included in the quantitative analysis. The average DC values (%) for 0-h/top, 0-h/bottom, 24-h/top, and 24-h/bottom were 59.09, 57.14, 66.73, and 63.87, respectively. According to their SUCRA ranking, the best-performing composites were: SonicFill, Venus Bulk Fill, and SDR (0-h/top), Reveal HD, i-Flow Bulk Fill, and Venus Bulk- Fill (0-h/bottom), Venus Bulk Fill, SDR, and QuiXfil (24-h/top), and Venus Bulk Fill, Aura Bulk Fill, and i-Flow Bulk Fill (24-h/bottom). Incoherence between direct and indirect evidence was identified as the most significant factor affecting confidence. CONCLUSIONS: DC values of bulk-fill composites were within the range commonly reported for previous generations of "conventional" composites, with flowable composites tending to perform better than sculptable composites. High variability in DC data was observed, which may be attributed to incompletely understood methodological differences. CLINICAL SIGNIFICANCE: DC is a fundamental parameter that influences multiple mechanical and biological properties of resin composites and is particularly relevant for the group of bulk-fill composites that are designed for use in thick layers.

Preliminary Study on Polymerization between Hemoglobin and Enzymes during the Preparation of PolyHb-SOD-CAT-CA.

The objective of this study was to explore the influence of different factors on the aggregation effect on hemoglobin (Hb) and enzymes during the preparation of Polyhemoglobin-Superoxide dismutase-Catalase-Carbonic anhydrase (PolyHb-SOD-CAT-CA). Several factors including temperatures, pH values, Glutaraldehyde (GDA) amounts and enzymes amounts were investigated systematically to study their effects on the enzymes recoveries and polymerization rates including the Superoxide dismutase (SOD), Catalase (CAT) and Carbonic anhydrase (CA), as well as their effects on the molecular weight distribution of PolyHb-SOD-CAT-CA. Then the oxygen affinity and methemoglobin (MetHb) contents of obtained PolyHb-SOD-CAT-CA were measured to evaluate the effects of enzyme crosslinking on the properties of Polyhemoglobin (PolyHb) moieties in the molecular structure of obtained PolyHb-SOD-CAT-CA conjugate. The results showed that the enzyme recoveries and polymerization rates could be decreased with the temperatures increasing and could be generally kept stable in the physiological pH conditions, but presented only slight changes among the investigated enzyme amounts ranges. Although the GDA concentration increasing could promote the enzyme polymerization rates, the enzyme recoveries decreased in whole. The polymerization rate and molecular size of PolyHb-SOD-CAT-CA conjugate increased with the elevation of temperature and the concentration of GDA. Lastly, the P50 values, Hill coefficients, and MetHb contents of PolyHb-SOD-CAT-CA conjugate with different enzyme crosslinking degrees exhibited no obvious differences with each other. In conclusion, the polymerization reactions between enzymes and Hb molecules could be remarkably affected by temperatures, pH values, and GDA amounts, and the enzyme crosslinking presented no obvious effects on the Hb properties, especially about the oxygen affinity and oxidation degrees.

High-purity butoxydibutylborane catalysts enable the low-exothermic polymerization of PMMA bone cement with enhanced biocompatibility and osseointegration.

Polymethyl methacrylate (PMMA) based biomaterials have been widely utilized in clinics. However, currently, PMMA catalyzed by benzoyl peroxide (BPO) exhibits disquieting disadvantages including an exothermic polymerization reaction and a lack of bioactivity. Here, we first designed three industrial-scale synthesis methods for high-purity butoxydibutylborane (BODBB), achieving purity levels greater than 95% (maximum: 97.6%) and ensuring excellent fire safety. By utilizing BODBB as a catalyst, the highest polymerization temperature of PMMA bone cement (PMMA-BODBB) reached only 36.05 °C, ensuring that no thermal damage occurred after implantation. Compared to PMMA catalyzed by BPO and partially oxidized tributylborane (TBBO, catalyst of Super Bond C&B), PMMA-BODBB exhibited superior cell adhesion, proliferation, and osteogenesis, attributed to the reduced release of free radicals and toxic monomer, and moderate bioactive boron release. After injection into a 5 mm defect in the rat cranial bone, PMMA-BODBB demonstrated the highest level of osteointegration. This work not only presents an industrial-scale synthesis of high-purity BODBB, but also offers an innovative PMMA biomaterial system with intrinsic biocompatibility and osseointegration, paving the way for the next generation of PMMA-based biomaterials with broader applications.

Marginal integrity and physicomechanical properties of a thermoviscous and regular bulk-fill resin composites.

OBJECTIVES: To evaluate the marginal integrity (MI%) and to characterize specific properties of a thermoviscous bulk-fill resin composite, two regular bulk-fill resin composites, and a non-bulk-fill resin composite. MATERIALS AND METHODS: VisCalor bulk (VBF), Filtek One Bulk Fill (OBF), and Aura Bulk Fill (ABF) were evaluated. Filtek Z250 XT (ZXT) was used as non-bulk-fill control. MI% was evaluated in standardized cylindrical cavities restored with the composites by using a 3D laser confocal microscope. The following properties were characterized: volumetric polymerization shrinkage (VS%), polymerization shrinkage stress (Pss), degree of conversion (DC%), microhardness (KHN), flexural strength (FS), and elastic modulus (EM). Data were analyzed by one-way and two-way ANOVA, and Tukey HSD post-hoc test (α = 0.05). RESULTS: VBF presented the highest MI% and the lowest VS% and Pss (p < 0.05). DC% ranged from 59.4% (OBF) to 71.0% (ZXT). ZXT and VBF presented similar and highest KHN than OBF and ABF (p < 0.05). ABF presented the lowest FS (p < 0.05). EM ranged from 5.5 GPa to 7.7 GPa, with the values of ZXT and VBF being similar and statistically higher than those of OBF and ABF (p < 0.05). CONCLUSIONS: Thermoviscous technology employed by VisCalor bulk was able to improve its mechanical behavior comparatively to regular bulk-fill resin composites and to contribute to a better marginal integrity in restorations built up in cylindrical cavities with similar geometry to a class I cavity as well. Although presenting overall better physicomechanical properties, Z250 XT presented the worst MI%. CLINICAL RELEVANCE: The marginal integrity, which is pivotal for the success of resin composite restorations, could be improved using VisCalor bulk-fill. The worst MI% presented by Z250 XT reinforces that non-bulk-fill resin composites shall not be bulk-inserted in the cavity to be restored.

Construction of a durable, halogen-free, and phosphorus-free flame retardant cotton fabric system with hydrophobic properties by phase separation and interface polymerization.

Inspired by the synthesis of polyurethane, a multifunctional fabric with hydrophobic and long-lasting flame retardancy was prepared through the phase separation and interfacial reaction process between PEI (polyethyleneimine)/BX (borax) aqueous solution and isocyanate terminated polydimethylsiloxane (PDMS-NCO) in tetrahydrofuran solution. The limit oxygen index of the treated fabric increased from 18.0 % to 33.7 %, and the total heat release decreased by 34.2 %. The enhancement of flame retardant performance and thermal stability is attributed to the enhanced char-forming capacity. After 50 cycles of water washing, the cotton fabric can still pass the vertical flammability test because of the curing effect of PDMS-NCO on functional additives. Furthermore, SEM analysis revealed that the formation of nano-rough structures on the fibers was promoted by phase separation, thus leading an increased water contact angle of sample to 139°. The materials utilized in this modified process do not contain elements such as F, Cl, Br, and P, indicating its potential as an environmentally friendly methodology for fabric functionalization.

Characterization of a longan pericarp browning related peroxidase with a focus on its role in proanthocyanidin and lignin polymerization.

The longan pericarp turns brown dramatically after harvesting, but the mechanism is not well understood. In this work, two peroxidases were purified from longan pericarp and found to be identical to the class III peroxidases PRX53-2 and PRX53-3. In vitro, PRX53-2/3 catalyzed the browning of several pericarp abundant proanthocyanidin and lignin monomers, such as (-)-epicatechin (EC), (+)-catechin (CT) and coniferyl alcohol (ConA). PRX53-2 was upregulated and highly-expressed, while PRX53-3 was expressed at low levels after harvesting; thus, PRX53-2 was considered a browning-related gene. The reaction with both proanthocyanidin and lignin presented a greater degree of brown coloration compared to the single substrate reactions. Several procyanidins isomers, EC-ConA and CT-ConA were detected in the double-substrate reaction. These results not only demonstrate that the effects of PRX53-2 on proanthocyanidin and lignin polymerization may be crucial for longan pericarp browning, but also help in developing new strategies or preservatives to delay pericarp browning.

Self-healing cellulose nanocrystals/fluorinated polyacrylate with double dynamic interactions of coumarin groups and multiple hydrogen bonds.

In this work, self-healing cellulose nanocrystals/fluorinated polyacrylate with dual dynamic networks of photoreversible crosslinking network and high-density hydrogen bonds was prepared by Pickering emulsion polymerization. The main work was to study the effects of 7-(2-methacryloyloxy)-4-methylcoumarin (CMA) and 2-ureido-4[1H]-pyrimidinone methyl methacrylate (UPyMA) monomer dosage on emulsion polymerization and latex film properties. The monomer conversion increased first and then decreased as the CMA and UPyMA monomer dosage increased, while a reverse trend was noted for the particle size and particle size distribution. Incorporating UPyMA allowed the rapid formation of hydrogen bonds at the crosslinking sites, which increased the interaction force between the healing surfaces. Besides, reversible photocrosslinking reaction of coumarin groups provided another support for self-healing performance. Moreover, the influence of self-healing temperature, self-healing time and UV irradiation on the self-healing ability was also systematically investigated The tensile strength of the prepared cellulose nanocrystals/fluorinated polyacrylate latex film exhibited a self-healing efficiency of 91.4 % under 365 nm UV irradiation and 80 °C for 12 h. The latex film had excellent thermal stability as was shown by TG and DTG analyses. The outstanding self-healing capability of latex film was attributed to the reversible photodimerization of coumarin groups and multiple hydrogen bonds. In addition, the water-oil repellent and mechanical properties of the latex films were improved as the CMA and UPyMA monomer dosage increased.

On the generation of force required for actin-based motility.

The fundamental question of how forces are generated in a motile cell, a lamellipodium, and a comet tail is the subject of this note. It is now well established that cellular motility results from the polymerization of actin, the most abundant protein in eukaryotic cells, into an interconnected set of filaments. We portray this process in a continuum mechanics framework, claiming that polymerization promotes a mechanical swelling in a narrow zone around the nucleation loci, which ultimately results in cellular or bacterial motility. To this aim, a new paradigm in continuum multi-physics has been designed, departing from the well-known theory of Larché-Cahn chemo-transport-mechanics. In this note, we set up the theory of network growth and compare the outcomes of numerical simulations with experimental evidence.