To investigate the clinical and imaging characteristics of computed tomography (CT) in novel coronavirus pneumonia (NCP) caused by SARS-CoV-2.
A retrospective analysis was performed on the imaging ...findings of patients confirmed with COVID-19 pneumonia who had chest CT scanning and treatment after disease onset. The clinical and imaging data were analyzed.
Fifty patients were enrolled, including mild type in nine, common in 28, severe in 10 and critically severe in the rest three. Mild patients (29 years) were significantly (P<0.03) younger than either common (44.5 years) or severe (54.7) and critically severe (65.7 years) patients, and common patients were also significantly (P<0.03) younger than severe and critically severe patients. Mild patients had low to moderate fever (<39.1 °C), 49 (98%) patients had normal or slightly reduced leukocyte count, 14 (28%) had decreased counts of lymphocytes, and 26 (52%) patients had increased C-reactive protein. Nine mild patients were negative in CT imaging. For all the other types of NCP, the lesion was in the right upper lobe in 30 cases, right middle lobe in 22, right lower lobe in 39, left upper lobe in 33 and left lower lobe in 36. The lesion was primarily located in the peripheral area under the pleura with possible extension towards the pulmonary hilum. Symmetrical lesions were seen in 26 cases and asymmetrical in 15. The density of lesion was mostly uneven with ground glass opacity as the primary presentation accompanied by partial consolidation and fibrosis.
CT imaging presentations of NCP are mostly patchy ground glass opacities in the peripheral areas under the pleura with partial consolidation which will be absorbed with formation of fibrotic stripes if improved. CT scanning provides important bases for early diagnosis and treatment of NCP.
•Underwater superoleophobic cotton fabric was prepared by a mussel-inspired method.•The underwater superoleophobic cotton fabric is efficient in oil/water separation.•The underwater superoleophobic ...cotton fabric exhibited outstanding mechanical resistance.•The underwater superoleophobic cotton fabric showed excellent chemical resistance.
Superhydrophilic and underwater superoleophobic textiles exhibit excellent oil/water separation performance but are limited by the poor stability and environmental incompatibility. Inspired by strong adhesion of marine mussels, we designed and fabricated a stable and eco-friendly superhydrophilic and underwater superoleophobic cotton fabric (CF) from all renewable resources through in-situ surface deposition of polydopamine (PDA) particles followed by adsorption of hydrophilic chitosan via dip coating at room temperature. The as-prepared superhydrophilic and underwater superoleophobic CF exhibited outstanding oil/water separation performance with separation efficiency and water flux higher than 99 % and 15,000 L m−2 h-1, respectively. Moreover, it not only showed excellent resistance to mechanical abrasion and ultrasound treatment but also had outstanding superwetting stability against acid/alkali/salt erosion. We believed that the eco-friendly superhydrophilic and underwater superoleophobic CF would exhibit great potential in oil/water separation especially under harsh conditions.
Poly(lactic acid) (PLA) is regarded as one of the most promising biobased and biodegradable polymers due its various advantages including high mechanical strength, easy processability, high melting ...temperature, renewability, biodegradability, and biocompatibility. However, the inherent brittleness significantly restricts its wide application. Therefore, toughening PLA has attracted more and more attention and various materials have been used to blend with PLA for toughening. Considering the fact that the use of petroleum-based species to toughen PLA would partially sacrifice the sustainability, various renewable polymers have recently been employed to toughen PLA. A series of important achievements have been obtained but not reviewed. This article aims to review progress in toughening PLA with renewable polymers. The toughening theories and compatibilization strategies are also briefly introduced.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Thermosets have many advantages such as excellent mechanical properties, dimensional stability, and chemical and environmental resistance, but suffer from unsustainability because they cannot be ...reprocessed, are difficult to recycle, and are overdependent on petroleum chemicals. Biobased covalent adaptable networks (CANs) represent a new type of crosslinking polymer derived from biomass-derived feedstocks and crosslinked by dynamic covalent bonds (DCBs). Biobased CANs provide an alternative solution to the sustainable development of traditional thermosetting polymers because they are not only not dependent on petroleum chemicals, but are also reprocessable and recyclable through the exchange reaction of DCBs under suitable conditions. Moreover, biobased CANs exhibit some other attractive functionalities such as self-healing, weldability, configurability, shape memory, and intelligent response. In such contexts, much effort has been devoted to designing and synthesizing biobased CANs from various biomass-derived chemicals such as vegetable oils, lignin and its derivatives, natural rubber, and sugars by incorporating various existing or designed DCBs, and notable progress has been achieved in this field. In this review, we summarize the recent progress on the design and synthesis of biobased CANs and suggest opportunities and challenges for their future development.
Thermosets have many advantages such as excellent mechanical properties, dimensional stability and environmental resistance, but suffer from unsustainability because they are difficult to recycle and overdependent on petroleum chemicals.
Despite the importance of stem cells in plant and animal development, the common mechanisms of stem cell maintenance in both systems have remained elusive. Recently, the importance of hydrogen ...peroxide (H2O2) signaling in priming stem cell differentiation has been extensively studied in animals. Here, we show that different forms of reactive oxygen species (ROS) have antagonistic roles in plant stem cell regulation, which were established by distinct spatiotemporal patterns of ROS‐metabolizing enzymes. The superoxide anion (O2·−) is markedly enriched in stem cells to activate WUSCHEL and maintain stemness, whereas H2O2 is more abundant in the differentiating peripheral zone to promote stem cell differentiation. Moreover, H2O2 negatively regulates O2·− biosynthesis in stem cells, and increasing H2O2 levels or scavenging O2·− leads to the termination of stem cells. Our results provide a mechanistic framework for ROS‐mediated control of plant stem cell fate and demonstrate that the balance between O2·− and H2O2 is key to stem cell maintenance and differentiation.
Synopsis
Superoxide regulates plant stem cell fate, and the balance between superoxide and H2O2 serves as a key switch for stem cell maintenance versus differentiation by antagonistically regulating expression of stem cell fate transcription factor WUSCHEL.
Superoxide specifically accumulates in plant stem cells to determine the stem‐cell fate.
H2O2 is enriched in the differentiating peripheral zone to promote plant stem cell differentiation.
Repression of superoxide dismutases and activation of peroxidases establishes the high superoxide and low H2O2 distribution patterns in plant stem cells.
H2O2 negatively regulates superoxide accumulation in stem cells by inhibiting key enzymes in superoxide anabolism.
The superoxide/H2O2 balance controls plant stem cell fate by antagonistically regulating WUSCHEL expression.
Superoxide regulates plant stem cell fate, and the balance between superoxide and H2O2 serves as a key switch for stem cell maintenance versus differentiation by antagonistically regulating expression of stem cell fate transcription factor WUSCHEL.
The substitution of petroleum-based self-healing elastomers with biobased counterparts is crucial to the global sustainable development of the rubber industry, which highly depends on the ease of the ...synthesis procedure. Herein, we show that highly stretchable, recyclable, and self-healable biobased elastomers were synthesized via condensation polymerization of succinic acid, adipic acid, sebacic acid, and 1,4-butanediol in the presence of a small amount of glycerol as a curing agent and 3,3′-dithiodipropionic acid as a dynamic covalent monomer. The macroscopic properties of our elastomers, including thermal, mechanical, stress relaxation, and self-healing performance, were finely regulated via microscopic chemical and topological structure. As such, a highly stretchable (up to ∼1700%), recyclable (almost without degradation of the mechanical performance over several repeats), rapid room temperature self-healable (in 20 min) biobased vitrimeric elastomer was achieved, which is the first aliphatic disulfide metathesis assisted self-healing polymer achieved at such low temperatures. The ease of the polycondensation with which the elastomers can be readily scaled up points to exciting opportunities for sustainable polymers with minimal environmental impact.
Epoxy thermosets have outstanding physical and chemical properties, but they are unrecyclable/non-degradable due to their permanently cross-linked networks, and are also overly dependent on fossil ...resources. This leads to serious environmental problems and resource depletion, which limit the sustainability of epoxy thermosets. Biobased epoxy covalent adaptable networks (CANs) are emerging polymers cross-linked with dynamic covalent bonds (DCBs) and derived from renewable biomass resources. Based on the exchange reactions of DCBs, they are recyclable and degradable, with other attractive functionalities such as self-healing, weldability, and reconfigurability. Therefore, biobased epoxy CANs provide a new method for the sustainable development of epoxy thermosets. This review summarizes recent advances in biobased epoxy CAN research. The design, synthesis, and properties of biobased epoxy CANs are discussed, and opportunities and challenges for their future development are also suggested.
The progress in design and synthesis of biobased covalent adaptable networks has been reviewed and their opportunities and challenges for future development are proposed.
Malleable and thermally recyclable polyurethane foam Wang, Xiang-Zhao; Lu, Meng-Shi; Zeng, Jian-Bing ...
Green chemistry : an international journal and green chemistry resource : GC,
01/2021, Letnik:
23, Številka:
1
Journal Article
Recenzirano
Thermosetting polyurethane (PU) foams, which cannot be recycled economically and efficiently due to their permanently crosslinked structures, have caused significant environmental concerns after ...service. To improve the sustainable development of the PU foam industry, herein, we report malleable PU foams that contain a dynamic disulfide bond. The disulfide exchange reaction under heat enables the rearrangement of the network topology of the PU foam, imparting malleability and thermal processability. The disulfide containing PU foams (PUSFs) have similar appearance and physical properties to common PU foams and were prepared using conventional foaming technology without any modification. The PUSFs can be easily recycled into PU films through thermal compression molding. The recycled PU films show excellent and tunable mechanical properties depending on the compositions of the original malleable PU foams. Furthermore, the PU film recycled from PU foam with a well-designed composition can be further reprocessed several times without obvious loss in mechanical proprieties and change in chemical structures. This investigation provides a novel methodology to recycle and reuse PU foams and is expected to promote the sustainable development of the PU foam industry.
Malleable polyurethane (PU) foams bearing disulfide bond were fabricated using conventional foaming technology and could be thermally recycled into PU films through compression molding.
The use of soybean oil or its derivatives to toughen polylactide (PLA) usually leads to limited toughening efficiency, due to the incompatibility between toughening agents and parent PLA. Herein, we ...report a dynamic vulcanization method to toughen PLA using sebacic acid cured epoxidized soybean oil (VESO), a fully sustainable and biodegradable component. A series of sebacic acid cured epoxidized soybean oil precursors (SEPs) were prepared with different carboxyl/epoxy equivalent ratio (R), which consequently dictates the chemical structure and the morphology of PLA/VESO blends after the dynamic vulcanization. We demonstrated that the chemical structure of VESO plays a critical role in the compatibility, morphology, and toughness of the PLA/VESO blends. By optimizing the R-value, supertoughened PLA blends can be obtained, as evidenced by the significant improvement in the tensile toughness (up to 150.6 MJ/m3) and the impact strength (up to 542.3 J/m). The results of the toughening mechanism from the morphology study confirm that the chemical structure of VESO is the key indicator of the toughening efficiency. For the PLA/VESO blends, at optimized R-value, the fracture energy can be dissipated efficiently through shear yielding of the PLA matrix induced by internal VESO cavitation to achieve supertoughness.
A novel biobased epoxy vitrimer (Gte-VA) with desirable mechanical properties was synthesized from glycerol triglycidyl ether (Gte) and an imine-containing hardener (VA), which was also a biobased ...compound from vanillin and 4-aminophenol. The biobased epoxy vitrimer shows Young’s modulus of 1.6 GPa and tensile strength of 62 MPa, which is close to the value of amine-cured bisphenol A diglycidyl ether. In addition, it shows excellent reprocessability, recyclability, and UV shielding performance and can be used as a matrix to prepare carbon fiber (CF)-reinforced composites. Based on the amine–imine reversible exchange reaction of the imine bonds, the CF fabric could be recycled without damage from the composite, after degrading the resin in an amine solution. Especially, after recombining the degraded resin with recycled carbon fiber fabric, a regenerated carbon fiber reinforced composite with similar mechanical properties to the original composite can be obtained, achieving full recycling of the carbon fiber reinforced composite. This work will open a door to the development of simple procedures of high-performance biobased epoxy vitrimer and its application in fully recycled carbon fiber reinforced composite.
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