Chemical-free Reactive Melt Processing of Biosourced Poly(butylene-succinate-adipate) for Improved Mechanical Properties and Recyclability.

Biosourced and biodegradable polyesters like poly(butylene succinate-co-butylene adipate) (PBSA) are gaining traction as promising alternatives to oil-based thermoplastics for single-use applications. However, the mechanical and rheological properties of PBSA are affected by its thermomechanical sensitivity during its melt processing, also hindering PBSA mechanical recycling. Traditional reactive melt processing (RP) methods use chemical additives to counteract these drawbacks, compromising sustainability. This study proposes a green reactive method during melt compounding for PBSA based on a comprehensive understanding of its thermomechanical degradative behavior. Under the hypothesis that controlled degradative paths during melt processing can promote branching/recombination reactions without the addition of chemical additives, we aim to enhance PBSA rheological and mechanical performance. An in-depth investigation of the in-line rheological behavior of PBSA was conducted using an internal batch mixer, exploring parameters such as temperature, screw rotation speed, and residence time. Their influence on PBSA chain scissions, branching/recombination, and cross-linking reactions were evaluated to identify optimal conditions for effective RP. Results demonstrate that specific processing conditions, for example, twelve minutes processing time, 200 °C temperature, and 60 rpm screw rotation speed, promote the formation of the long chain branched structure in PBSA. These structural changes resulted in a notable enhancement of the reacted PBSA rheological and mechanical properties, exhibiting a 23% increase in elastic modulus, a 50% increase in yield strength, and an 80% increase in tensile strength. The RP strategy also improved PBSA mechanical recycling, thus making it a potential replacement for low-density polyethylene (LDPE). Ultimately, this study showcases how finely controlling the thermomechanical degradation during reactive melt processing can improve the material's properties, enabling reliable mechanical recycling, which can serve as a green approach for other biodegradable polymers.

Fusion-fission-mitophagy cycling and metabolic reprogramming coordinate nerve growth factor (NGF)-dependent neuronal differentiation.

Neuronal differentiation is regulated by nerve growth factor (NGF) and other neurotrophins. We explored the impact of NGF on mitochondrial dynamics and metabolism through time-lapse imaging, metabolomics profiling, and computer modeling studies. We show that NGF may direct differentiation by stimulating fission, thereby causing selective mitochondrial network fragmentation and mitophagy, ultimately leading to increased mitochondrial quality and respiration. Then, we reconstructed the dynamic fusion-fission-mitophagy cycling of mitochondria in a computer model, integrating these processes into a single network mechanism. Both the computational model and the simulations are able to reproduce the proposed mechanism in terms of mitochondrial dynamics, levels of reactive oxygen species (ROS), mitophagy, and mitochondrial quality, thus providing a computational tool for the interpretation of the experimental data and for future studies aiming to detail further the action of NGF on mitochondrial processes. We also show that changes in these mitochondrial processes are intertwined with a metabolic function of NGF in differentiation: NGF directs a profound metabolic rearrangement involving glycolysis, TCA cycle, and the pentose phosphate pathway, altering the redox balance. This metabolic rewiring may ensure: (a) supply of both energy and building blocks for the anabolic processes needed for morphological reorganization, as well as (b) redox homeostasis.

Kraft Lignin: A Valuable, Sustainable Resource, Opportunities and Challenges.

Kraft lignin, a by-product from the production of pulp, is currently incinerated in the recovery boiler during the chemical recovery cycle, generating valuable bioenergy and recycling inorganic chemicals to the pulping process operation. Removing lignin from the black liquor or its gasification lowers the recovery boiler load enabling increased pulp production. During the past ten years, lignin separation technologies have emerged and the interest of the research community to valorize this underutilized resource has been invigorated. The aim of this Review is to give (1) a dedicated overview of the kraft process with a focus on the lignin, (2) an overview of applications that are being developed, and (3) a techno-economic and life cycle asseeements of value chains from black liquor to different products. Overall, it is anticipated that this effort will inspire further work for developing and using kraft lignin as a commodity raw material for new applications undeniably promoting pivotal global sustainability concerns.

Approaches in Sustainable, Biobased Multilayer Packaging Solutions.

The depletion of fossil resources and the growing demand for plastic waste reduction has put industries and academic researchers under pressure to develop increasingly sustainable packaging solutions that are both functional and circularly designed. In this review, we provide an overview of the fundamentals and recent advances in biobased packaging materials, including new materials and techniques for their modification as well as their end-of-life scenarios. We also discuss the composition and modification of biobased films and multilayer structures, with particular attention to readily available drop-in solutions, as well as coating techniques. Moreover, we discuss end-of-life factors, including sorting systems, detection methods, composting options, and recycling and upcycling possibilities. Finally, regulatory aspects are pointed out for each application scenario and end-of-life option. Moreover, we discuss the human factor in terms of consumer perception and acceptance of upcycling.

Three Dimensional Printed Surgical Guides: Effect of Time on Dimensional Stability.

PURPOSE: To analyze, in vitro, the dimensional stability over time of 3D-printed surgical guides. MATERIALS AND METHODS: Ten surgical guides, manufactured by digital light processing 3D-printing technology, were scanned immediately after post-processing and then after 5, 10, 15, and 20 days. The corresponding standard tessellation language (STL) files were used for comparison with the reference CAD project. Mean absolute deviation (MAD) of the intaglio surface, axial, and linear deviations of the sleeves' housings were measured. Generalized estimated equations models (α = 0.05) were used to investigate the effect of time. RESULTS: MAD of the teeth intaglio surface showed less variation (minimum: 0.002, maximum: 0.014 mm) than that of the mucosa (minimum: 0.026, maximum: 0.074 mm). Axial variations of the sleeves' housings on the sagittal (minimum: -0.008°, maximum: -0.577°) and frontal plane (minimum: -0.193°, maximum: 0.525°) changed with similar patterns, but opposite trends (decreasing for the former). Linear deviations of center points of the sleeves' housings had a shifting (minimum: -0.074, maximum: 0.02 mm) pattern with a decreasing tendency. Time after processing had a significant effect, either alone or nested with guides volume, on all outcomes of interest, except for MAD of the mucosa intaglio surface (p < 0.001), which was significantly affected only by the time-volume nested effect (p = 0.012). CONCLUSIONS: Within the limitations of the experimental design, postmanufacturing dimensional variations of surgical guides were statistically significant. Although limited, they are an additional source of variability affecting the overall accuracy of computer-guided surgery. As such, they should be addressed by further research.

Valorization of Ferulic Acid from Agro-Industrial by-Products for Application in Agriculture.

The use of bioplastic mulch in agriculture has increased dramatically in the last years throughout the world. Nowadays, biodegradable materials for mulching films strive to constitute a reliable and more sustainable alternative to classical materials such as polyethylene (PE). The main challenge is to improve their durability in the soil to meet the required service length for crop farming by using benign and sustainable antioxidant systems. Here, we report the design and fabrication of biodegradable materials based on polybutylene (succinate adipate) (PBSA) for mulching applications, incorporating a fully biobased polymeric antioxidant deriving from ferulic acid, which can be extracted from an industrial by-product. Poly-dihydro (ethylene ferulate) (PHEF) from ferulic acid was synthesized by a two-step polymerization process. It is characterized by improved thermal stability in comparison with ferulic acid monomer and therefore suitable for common industrial processing conditions. Different blends of PBSA and PHEF obtained by melt mixing or by reactive extrusion were prepared and analyzed to understand the effect of the presence of PHEF. The results demonstrate that PHEF, when processed by reactive extrusion, presents a remarkable antioxidant effect, even in comparison with commercial additives, preserving a high level of the mechanical properties of the PBSA matrix without affecting the biodegradable character of the blend.

Current Advances in the Sustainable Conversion of 5-Hydroxymethylfurfural into 2,5-Furandicarboxylic Acid.

2,5-Furandicarboxylic acid (FDCA) is currently considered one of the most relevant bio-sourced building blocks, representing a fully sustainable competitor for terephthalic acid as well as the main component in green polymers such as poly(ethylene 2,5-furandicarboxylate) (PEF). The oxidation of biobased 5-hydroxymethylfurfural (HMF) represents the most straightforward approach to obtain FDCA, thus attracting the attention of both academia and industries, as testified by Avantium with the creation of a new plant expected to produce 5000 tons per year. Several approaches allow the oxidation of HMF to FDCA. Metal-mediated homogeneous and heterogeneous catalysis, metal-free catalysis, electrochemical approaches, light-mediated procedures, as well as biocatalytic processes share the target to achieve FDCA in high yield and mild conditions. This Review aims to give an up-to-date overview of the current developments in the main synthetic pathways to obtain FDCA from HMF, with a specific focus on process sustainability.

Aerosol transmission for SARS-CoV-2 in the dental practice. A review by SIdP Covid-19 task-force.

Current evidence suggests that SARS-CoV-2, the virus that causes COVID-19, is predominantly spread from person to person. Aim of this narrative review is to explore transmission modality of SARS-CoV-2 to provide appropriate advice to stakeholders, in order to support the implementation of effective public health measures and protect healthcare workers that primary face the disease. "In vivo" and "in vitro" studies from laboratories and hospitals confirmed the presence of surface contamination and provided insight of SARS-CoV-2 detection in the air, particularly in indoor settings with poor ventilation where aerosol-generating procedures were performed. Measures for aerosol reduction, in conjunction with other effective infection control strategies, are needed to prevent the spread of SARS-CoV-2 in dental setting.

Surface disinfection and protective masks for SARS-CoV-2 and other respiratory viruses: A review by SIdP COVID-19 task force.

OBJECTIVES: Primary focused question for this systematic review (SR) was "Which is the evidence about surfaces decontamination and protection masks for SARS-Cov-2 in dental practice?" Secondary question was "Which is the evidence about surfaces decontamination and protection masks against airborne pathogens and directly transmitted viral pathogens causing respiratory infections?" MATERIALS AND METHODS: PRISMA guidelines were used. Studies on surface decontamination and protective masks for SARS-CoV-2 in dental practice were considered. Studies on other respiratory viruses were considered for the secondary question. RESULTS: No studies are available for SARS-CoV-2. Four studies on surface disinfection against respiratory viruses were included. Ethanol 70% and sodium hypochlorite 0,5% seem to be effective in reducing infectivity by > 3log TCID. Four RCTs compared different types of masks on HCW. The single studies reported no difference for laboratory-diagnosed influenza, laboratory-diagnosed respiratory infection, and influenza-like illness. A meta-analysis was not considered appropriate. CONCLUSIONS: There is lack of evidence on the efficacy of surface disinfection and protective masks to reduce the spread of SARS-CoV-2 or other respiratory viruses in dentistry. However, the consistent use of respirator and routine surface disinfection is strongly suggested. There is urgent need of data on the efficacy of specific protection protocols for dental HCW against viral infections.

End of Life of Biodegradable Plastics: Composting versus Re/Upcycling.

Nowadays the issues related to the end of life of traditional plastics are very urgent due to the important pollution problems that plastics have caused. Biodegradable plastics can help to try to mitigate these problems, but even bioplastics need much attention to carefully evaluate the different options for plastic waste disposal. In this Minireview, three different end-of-life scenarios (composting, recycling, and upcycling) were evaluated in terms of literature review. As a result, the ability of bioplastics to be biodegraded by composting has been related to physical variables and materials characteristics. Hence, it is possible to deduce that the process is mature enough to be a good way to minimize bioplastic waste and valorize it for the production of a fertilizer. Recycling and upcycling options, which could open up many interesting new scenarios for the production of high-value materials, are less studied. Research in this area can be strongly encouraged.

Water Vapor Sorption and Diffusivity in Bio-Based Poly(Ethylene Vanillate)-PEV.

The dynamic and equilibrium water vapor sorption properties of amorphous and highly crystalline poly(ethylene vanillate) (PEV) films were determined via gravimetric analysis, at 20 °C, over a wide range of relative humidity (0-95% RH). At low RH%, the dynamic of the sorption process obeys Fick's law while at higher relative humidity it is characterized by a drift ascribable to non-Fickian relaxations. The non-Fickian relaxations, which are responsible for the incorporation of additional water, are correlated with the upturn of the sorption isotherms and simultaneously the hysteresis recorded between sorption and desorption cycles. The sorption isotherms of amorphous and highly crystalline PEV are arranged in the same concentration range of that of PET proving the similarity of the two polyesters. Water diffusion coefficients, whose determination from individual kinetic sorption/desorption curves required treatment with the Barens-Hopfenberg model, were demonstrated to be ≈ 10× higher for amorphous PEV compared to amorphous PET. Such a difference originates from the enhanced segmental flexibility of PEV chains.

Lignin-Based Epoxy Resins: Unravelling the Relationship between Structure and Material Properties.

Here we investigate the relationship between thermomechanical properties and chemical structure of well-characterized lignin-based epoxy resins. For this purpose, technical lignins from eucalyptus and spruce, obtained from the Kraft process, were used. The choice of lignins was based on the expected differences in molecular structure. The lignins were then refined by solvent fractionation, and three fractions with comparable molecular weights were selected to reduce effects of molar mass on the properties of the final thermoset resins. Consequently, any differences in thermomechanical properties are expected to correlate with molecular structure differences between the lignins. Oxirane moieties were selectively introduced to the refined fractions, and the resulting lignin epoxides were subsequently cross-linked with two commercially available polyether diamines (Mn = 2000 and 400) to obtain lignin-based epoxy resins. Molecular-scale characterization of the refined lignins and their derivatives were performed by 31P NMR, 2D-NMR, and DSC methods to obtain the detailed chemical structure of original and derivatized lignins. The thermosets were studied by DSC, DMA, and tensile tests and demonstrated diverse thermomechanical properties attributed to structural components in lignin and selected amine cross-linker. An epoxy resin with a lignin content of 66% showed a Tg of 79 °C from DMA, Young's modulus of 1.7 GPa, tensile strength of 66 MPa, and strain to failure of 8%. The effect of molecular lignin structure on thermomechanical properties was analyzed, finding significant differences between the rigid guaiacyl units in spruce lignin compared with sinapyl units in eucalyptus lignin. The methodology points toward rational design of molecularly tailored lignin-based thermosets.

Integrating intraoral, perioral, and facial scans into the design of digital dentures.

Digital technologies offer the opportunity to integrate facial scans into the design of digital dentures and provide a beneficial 3D preview and simulation of the tooth arrangement for both treatment planning and communication. The presented technique describes a procedure of merging and aligning the intraoral scans of edentulous arches, the scans of the perioral area, and the scan of the nose made by using an intraoral scanner, as well as facial scans made by using a mobile phone. Thus, a digital patient can be obtained and used to optimize individual tooth arrangement during the design of the digital denture.

Tunable Thermosetting Epoxies Based on Fractionated and Well-Characterized Lignins.

Here we report the synthesis of thermosetting resins from low molar mass Kraft lignin fractions of high functionality, refined by solvent extraction. Such fractions were fully characterized by 31P NMR, 2D-HSQC NMR, SEC, and DSC in order to obtain a detailed description of the structures. Reactive oxirane moieties were introduced on the lignin backbone under mild reaction conditions and quantified by simple 1H NMR analysis. The modified fractions were chemically cross-linked with a flexible polyether diamine ( Mn ≈ 2000), in order to obtain epoxy thermosets. Epoxies from different lignin fractions, studied by DSC, DMA, tensile tests, and SEM, demonstrated substantial differences in terms of thermo-mechanical properties. For the first time, strong relationships between lignin structures and epoxy properties could be demonstrated. The suggested approach provides unprecedented possibilities to tune network structure and properties of thermosets based on real lignin fractions, rather than model compounds.

A Sustainable Route to a Terephthalic Acid Precursor.

A new synthetic pathway for the production of p-toluic acid has been developed starting from reagents derived from renewable resources. A Diels-Alder reaction between sorbic and acrylic acids is followed by a combined dehydrogenation/ decarboxylation process, providing p-toluic acid in high yields. This route permits to use milder conditions compared to other Diels-Alder approaches reported in the literature, and therefore can contribute to a more sustainable terephthalic acid production.

Efficacy of aerobic physical retraining in a case of combined pulmonary fibrosis and emphysema syndrome: a case report.

INTRODUCTION: Combined pulmonary fibrosis and emphysema has recently been recognized as a syndrome but remains under-diagnosed. Neither clinical management nor therapeutic approaches have been clearly defined. Pulmonary rehabilitation has not been considered within the therapeutic options for combined pulmonary fibrosis and emphysema. In this case we explored the potential benefits of a specific aerobic physical retraining program in the management of combined pulmonary fibrosis and emphysema. CASE PRESENTATION: We describe the case of a 65-year-old Caucasian man with combined pulmonary fibrosis and emphysema and respiratory failure who was receiving long-term oxygen therapy. Our patient underwent physical retraining with moderate intensity aerobic and breathing exercises for four weeks. Clinical and motor tests, as well as questionnaires assessing quality of life and depression levels, were performed prior to and following the retraining. At the end of the retraining program a relevant reduction of long-term oxygen therapy requirement was registered; improvements in terms of physical performance, quality of life, and mood were observed in our patient but no change in respiratory parameters. CONCLUSIONS: A program of aerobic physical retraining appears to be beneficial to patients with combined pulmonary fibrosis and emphysema and may be considered as an additional therapeutic option.

Chitosan aerogel: a recyclable, heterogeneous organocatalyst for the asymmetric direct aldol reaction in water.

Aerogel microspheres of chitosan, an abundant biopolymer obtained from marine crustaceans, have been successfully applied to catalyze the asymmetric aldol reaction in water, providing the products in high yields and with good stereoselectivity (up to 93% ee) and recyclability (up to 4 runs). Yields were favourably affected by additives such as DNP and stearic acid.

Organocatalytic asymmetric formal [3 + 2] cycloaddition with in situ-generated N-carbamoyl nitrones.

A novel organocatalytic formal [3 + 2] cycloaddition reaction with in situ generation of N-carbamoyl nitrones is presented. For the first time, N-Boc- and N-Cbz-protected isoxazolidines have been directly obtained as single diastereoisomers in generally high yields and enantiomeric excesses using mild reaction conditions and inexpensive, readily available Cinchona alkaloid quaternary ammonium salts as catalysts. Synthetic manipulations of the products provided highly valuable building blocks such as free isoxazolidines, a N-Boc-1,3-aminoalcohol, and a free delta-lactam. This report represents a pioneering work in the use of N-carbamoyl nitrones as electron-poor 1,3-dipoles and glutaconates as new dipolarophiles in asymmetric catalysis.