Scale Synthesis of Poly(butylene carbonate-<i>co</i>-terephthalate) and Its Depolymerization–Repolymerization Recycling Process

Development of biodegradable aliphatic–aromatic copolyesters has been widely accepted by society as a promising strategy to solve plastic pollution. Here, a kilogram-scale aliphatic–aromatic copolyester, poly­(butylene carbonate-co-terephthalate) (PBCT), has been successfully synthesized using a 5 L steel reactor. The physical–chemical properties, including composition, microstructure, thermal properties, crystal structure, rheology behavior, mechanical properties, and water barrier property, were systematically investigated. The results illustrated that PBCT could be used as an ideal barrier packaging film material. In addition, the closed-loop recycling property of PBCT was preliminarily explored. The aromatic units of PBCT copolyesters were able to be recycled using the esterification byproduct, which consisted of methanol and dimethyl carbonate. The evolution of molar weights during the alcoholysis process indicated that PBCT could be completely converted to dimethyl terephthalate (DMT). The repolymerized PBCT prepared with the recycled DMT showed no significant property loss compared with the initial PBCT. This work provides a novel insight and direction for treating waste biodegradable polyesters, which could overcome the post-consumer plastic waste accumulation in the environment

MOESM1 of Pluronic-based nano-self-assemblies of bacitracin A with a new mechanism of action for an efficient in vivo therapeutic effect against bacterial peritonitis

Additional file 1. Synthesis and Characterization of BA-PEO-PPO-PEO-B

Brain-targeted delivery of PEGylated nano-bacitracin A against Penicillin-sensitive and -resistant Pneumococcal meningitis: formulated with RVG₂₉ and Pluronic^® P85 unimers

Pneumococcal meningitis (PM), caused by Streptococcus pneumonia, remains a high-burden disease in developing countries. Antibiotic therapy has been limited due to the inefficiency of drug transport across the blood-brain barrier (BBB) and the emergence of drug-resistant strains. In our preliminary study, PEGylated nano-self-assemblies of bacitracin A (PEGylated Nano-BA12K) demonstrated a strong antibacterial potency against S. pneumonia. In this study, the potential application of this micelle for the treatment of both Penicillin-sensitive and -resistant PM was studied. To address BBB-targeting and -crossing issues, PEGylated Nano-BA12K was formulated with a specific brain-targeting peptide (rabies virus glycopeptide-29, RVG29) and a P-glycoprotein inhibitor (Pluronic® P85 unimers) to construct a mixed micellar system (RVG29-Nano-BAP85). RVG29-Nano-BAP85 demonstrated a strong antibacterial potency against 13 clinical isolates of S. pneumonia, even higher than that of Penicillin G, a conventional anti-PM agent. RVG29-Nano-BAP85 had more cellular uptake in brain capillary endothelial cells (BCECs) and higher BBB-crossing efficiency than single formulated Nano-BAs as shown in an in vitro BBB model. The enhanced BBB-permeability was attributed to the synergetic effect of RVG29 and P85 unimers through receptor-mediated transcytosis, exhaustion of ATP, and reduction in membrane microviscosity. In vivo results further demonstrated that RVG29-Nano-BAP85 was able to accumulate in brain parenchyma as confirmed by in vivo optical imaging. In addition, RVG29-Nano-BAP85 exhibited high therapeutic efficiencies in both Penicillin-sensitive and -resistant PM mouse models with negligible systemic toxicity. Collectively, RVG29-Nano-BAP85 could effectively overcome BBB barriers and suppressed the growth of both drug-sensitive and -resistant S. pneumonia in the brain tissues, which demonstrated its potential for the treatment of PM.</p

Transferring deep knowledge for object recognition in Low-quality underwater videos

In recent years, underwater video technologies allow us to explore the ocean in scientific and noninvasive ways, such as environmental monitoring, marine ecology studies, and fisheries management. However the low-light and high-noise scenarios pose great challenges for the underwater image and video analysis. We here propose a CNN knowledge transfer framework for underwater object recognition and tackle the problem of extracting discriminative features from relatively low contrast images. Even with the insufficient training set, the transfer framework can well learn a recognition model for the special underwater object recognition task together with the help of data augmentation. For better identifying objects from an underwater video, a weighted probabilities decision mechanism is introduced to identify the object from a series of frames. The proposed framework can be implemented for real-time underwater object recognition on autonomous underwater vehicles and video monitoring systems. To verify the effectiveness of our method, experiments on a public dataset are carried out. The results show that the proposed method achieves promising results for underwater object recognition on both test image datasets and underwater videos

Transferring deep knowledge for object recognition in Low-quality underwater videos

In recent years, underwater video technologies allow us to explore the ocean in scientific and noninvasive ways, such as environmental monitoring, marine ecology studies, and fisheries management. However the low-light and high-noise scenarios pose great challenges for the underwater image and video analysis. We here propose a CNN knowledge transfer framework for underwater object recognition and tackle the problem of extracting discriminative features from relatively low contrast images. Even with the insufficient training set, the transfer framework can well learn a recognition model for the special underwater object recognition task together with the help of data augmentation. For better identifying objects from an underwater video, a weighted probabilities decision mechanism is introduced to identify the object from a series of frames. The proposed framework can be implemented for real-time underwater object recognition on autonomous underwater vehicles and video monitoring systems. To verify the effectiveness of our method, experiments on a public dataset are carried out. The results show that the proposed method achieves promising results for underwater object recognition on both test image datasets and underwater videos

Polyurea–Cellulose Composite Aerogel Fibers with Superior Strength, Hydrophobicity, and Thermal Insulation via a Secondary Molding Strategy

Aerogel materials, considered as the “miracle material that can change the world in the 21st century”, owe their transformative potential to their high specific surface area, porosity, and low density. In comparison to commercially available aerogel felt, aerogel particles, and aerogel powder, aerogel fibers not only possess the inherent advantages of aerogel materials but also exhibit exceptional flexibility and design versatility. Therefore, aerogel fibers are expected to be processed into high-performance textiles and smart wearable fabrics to further expand the application field of aerogel materials. However, the aerogel fibers suffer from poor mechanical properties and intricate, time-consuming preparation processes. Herein, a simple and efficient method for crafting polyurea–cellulose composite aerogel fibers (CAFs) with superior mechanical properties is presented. The dried bacterial cellulose (BC) matrix was immersed in a polyurea sol, and the aerogel fibers were prepared via secondary molding, followed by CO2 supercritical drying. In a representative case, the CAFs obtained via secondary molding demonstrate outstanding hydrophobicity with a contact angle of 126°, along with remarkable flexibility. Significantly, the CAFs exhibit excellent mechanical properties, including a tensile strength of 6.4 MPa. Moreover, the CAFs demonstrate superior thermal insulation capabilities, withstanding temperatures ranging from 180 to −40 °C. In conclusion, with the successful fabrication of polyurea–cellulose CAFs, this study introduces a magic approach for producing aerogel fibers endowed with exceptional mechanical properties and thermal insulation. This advancement contributes to the development and application of aerogel materials in various fields

Polyurea–Cellulose Composite Aerogel Fibers with Superior Strength, Hydrophobicity, and Thermal Insulation via a Secondary Molding Strategy

Aerogel materials, considered as the “miracle material that can change the world in the 21st century”, owe their transformative potential to their high specific surface area, porosity, and low density. In comparison to commercially available aerogel felt, aerogel particles, and aerogel powder, aerogel fibers not only possess the inherent advantages of aerogel materials but also exhibit exceptional flexibility and design versatility. Therefore, aerogel fibers are expected to be processed into high-performance textiles and smart wearable fabrics to further expand the application field of aerogel materials. However, the aerogel fibers suffer from poor mechanical properties and intricate, time-consuming preparation processes. Herein, a simple and efficient method for crafting polyurea–cellulose composite aerogel fibers (CAFs) with superior mechanical properties is presented. The dried bacterial cellulose (BC) matrix was immersed in a polyurea sol, and the aerogel fibers were prepared via secondary molding, followed by CO2 supercritical drying. In a representative case, the CAFs obtained via secondary molding demonstrate outstanding hydrophobicity with a contact angle of 126°, along with remarkable flexibility. Significantly, the CAFs exhibit excellent mechanical properties, including a tensile strength of 6.4 MPa. Moreover, the CAFs demonstrate superior thermal insulation capabilities, withstanding temperatures ranging from 180 to −40 °C. In conclusion, with the successful fabrication of polyurea–cellulose CAFs, this study introduces a magic approach for producing aerogel fibers endowed with exceptional mechanical properties and thermal insulation. This advancement contributes to the development and application of aerogel materials in various fields

Polyurea–Cellulose Composite Aerogel Fibers with Superior Strength, Hydrophobicity, and Thermal Insulation via a Secondary Molding Strategy

Aerogel materials, considered as the “miracle material that can change the world in the 21st century”, owe their transformative potential to their high specific surface area, porosity, and low density. In comparison to commercially available aerogel felt, aerogel particles, and aerogel powder, aerogel fibers not only possess the inherent advantages of aerogel materials but also exhibit exceptional flexibility and design versatility. Therefore, aerogel fibers are expected to be processed into high-performance textiles and smart wearable fabrics to further expand the application field of aerogel materials. However, the aerogel fibers suffer from poor mechanical properties and intricate, time-consuming preparation processes. Herein, a simple and efficient method for crafting polyurea–cellulose composite aerogel fibers (CAFs) with superior mechanical properties is presented. The dried bacterial cellulose (BC) matrix was immersed in a polyurea sol, and the aerogel fibers were prepared via secondary molding, followed by CO2 supercritical drying. In a representative case, the CAFs obtained via secondary molding demonstrate outstanding hydrophobicity with a contact angle of 126°, along with remarkable flexibility. Significantly, the CAFs exhibit excellent mechanical properties, including a tensile strength of 6.4 MPa. Moreover, the CAFs demonstrate superior thermal insulation capabilities, withstanding temperatures ranging from 180 to −40 °C. In conclusion, with the successful fabrication of polyurea–cellulose CAFs, this study introduces a magic approach for producing aerogel fibers endowed with exceptional mechanical properties and thermal insulation. This advancement contributes to the development and application of aerogel materials in various fields

Polyurea–Cellulose Composite Aerogel Fibers with Superior Strength, Hydrophobicity, and Thermal Insulation via a Secondary Molding Strategy

Aerogel materials, considered as the “miracle material that can change the world in the 21st century”, owe their transformative potential to their high specific surface area, porosity, and low density. In comparison to commercially available aerogel felt, aerogel particles, and aerogel powder, aerogel fibers not only possess the inherent advantages of aerogel materials but also exhibit exceptional flexibility and design versatility. Therefore, aerogel fibers are expected to be processed into high-performance textiles and smart wearable fabrics to further expand the application field of aerogel materials. However, the aerogel fibers suffer from poor mechanical properties and intricate, time-consuming preparation processes. Herein, a simple and efficient method for crafting polyurea–cellulose composite aerogel fibers (CAFs) with superior mechanical properties is presented. The dried bacterial cellulose (BC) matrix was immersed in a polyurea sol, and the aerogel fibers were prepared via secondary molding, followed by CO2 supercritical drying. In a representative case, the CAFs obtained via secondary molding demonstrate outstanding hydrophobicity with a contact angle of 126°, along with remarkable flexibility. Significantly, the CAFs exhibit excellent mechanical properties, including a tensile strength of 6.4 MPa. Moreover, the CAFs demonstrate superior thermal insulation capabilities, withstanding temperatures ranging from 180 to −40 °C. In conclusion, with the successful fabrication of polyurea–cellulose CAFs, this study introduces a magic approach for producing aerogel fibers endowed with exceptional mechanical properties and thermal insulation. This advancement contributes to the development and application of aerogel materials in various fields

Isolation and Functional Characterization of Multiple NADPH-Cytochrome P450 Reductase Genes from <i>Camellia sinensis</i> in View of Catechin Biosynthesis

Catechins are critical constituents for the sensory quality and health-promoting benefits of tea. Cytochrome P450 monooxygenases are required for catechin biosynthesis and are dependent on NADPH-cytochrome P450 reductases (CPRs) to provide reducing equivalents for their activities. However, CPRs have not been identified in tea, and their relationship to catechin accumulation also remains unknown. Thus, three CsCPR genes were identified in this study, all of which had five CPR-related conserved domains and were targeted to the endoplasmic reticulum. These three recombinant CsCPR proteins could reduce cytochrome c using NADPH as an electron donor. Heterologous co-expression in yeast demonstrated that all the three CsCPRs could support the enzyme activities of CsC4H and CsF3′H. Correlation analysis indicated that the expression level of CsCPR1 (or CsCPR2 or CsCPR3) was positively correlated with 3′,4′,5′-catechin (or total catechins) content. Our results indicate that the CsCPRs are involved in the biosynthesis of catechins in tea leaves