Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.373
Filtrar
1.
Waste Manag ; 155: 269-280, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36403411

RESUMO

Leachate leakage poses a serious environmental risk to the safety of surrounding soils and groundwater. A much faster approach to reflect landfill leakage is the premise to mitigate the ecological risk of landfills. In this study, two landfills (BJ and WZ) were selected to investigate the leaching characteristics of various pollutants along the vadose soil depths. The physiochemical properties of underlying soils including NO3--N, NO2--N, NH4+-N, OM, TN, EC and Cl- exhibited a typical leaching dynamic along the depths. Among them, TN, NH4+-N, OM, NO3--N, and EC might be used as characteristic pollutants to evaluate the leachate leakage issues in landfilled sites. The genera Thiopseudomonas, Acinetobacter, Pseudomonas, and Hydrogenispora dominated in underlying soils. Compared to BJ samples, a more diverse and active microbiome capable of carbon and nitrogen cycles was observed in WZ samples, which was mainly ascribed to nutrients and elements contained in different types of soils. Among the environmental factors, nitrogenous compounds, SO42-, pH and EC had significant effects on the microbial community structures in the underlying soils. The relative abundances of Hydrogenispora and Caldicoprobacter might be used as characteristic microorganisms to evaluate the leachate leakage issues in landfilled sites. These results provided a deep insight into effects of leachate leakage in underlying soils, especially the pollutants vertical distribution and the corresponding microbial community structures.


Assuntos
Poluentes Ambientais , Microbiota , Solo , Carbono , Instalações de Eliminação de Resíduos
2.
Chemosphere ; 311(Pt 1): 137010, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36326517

RESUMO

This paper explored the effects of the rest phase of tidal flow constructed wetlands (TFCW) on pollutant removal and microbial communities, and further analyzed the mechanism of TFCW removal of pollutants from grey water. The results showed that the removal rate of organic matter was 69.91 ± 2.44% in the control group (NR-TFCW) without the rest phase, 94.95 ± 1.17% in the experimental group (TFCW), and 96.95 ± 2.43% in the control group (P-TFCW) with the ventilation pipe enhanced rest phase. Limiting and enhancing the oxygen supply in the emptying stage of TFCW will enhance the overlap rate of microorganisms in the upper, middle and lower layers of the reactor. Enhancing the rest phase of TFCW leaded to better aerobic removal of organic matter in the microbial community, while limiting the rest phase of TFCW results in the opposite. In addition, the species overlap rate of the top, middle and bottom layers of NR-TFCW (69.98%) and P-TFCW (54.29%) was higher than that of TFCW (11.34%). The removal of organic matter by TFCW mainly relied on the adsorption of biochar in the flood phase, and the microorganisms aerobic degraded the organic matter adsorbed on the biochar in the rest phase. And thus form a continuous cycle of adsorption and biological regeneration. The microbial community in TFCW did not have the ability to nitrify, but had the ability to remove phosphorus. Ammonia nitrogen in the influent was adsorbed by biochar or converted into cytoplasm. While the phosphorus in the influent was adsorbed by the biochar, it was also being biologically removed.


Assuntos
Poluentes Ambientais , Purificação da Água , Áreas Alagadas , Desnitrificação , Nitrogênio , Fósforo , Eliminação de Resíduos Líquidos/métodos
3.
Artigo em Inglês | MEDLINE | ID: mdl-36460617

RESUMO

A long-standing quest in materials science has been the development of tough epoxy resin nanocomposites used in numerous applications. Inspired by nacre, herein, we report tough and conductive MXene/epoxy layered bulk nanocomposites. The orientation of MXene lamellar scaffolds is enhanced by annealing treatment. The improved interfacial interactions between MXene lamellar scaffold and epoxy through surface chemical modification resulted in a synergistic effect. Tailoring the interlayer spacing of MXene nanosheets to a critical distance resulted in the fracture toughness about eight times higher than pure epoxy, surpassing other epoxy nanocomposites. Our nacre-inspired MXene/epoxy layered bulk nanocomposites also show high electrical conductivity that provides self-monitoring capability to the structure integrity and exhibits an excellent electromagnetic interference shielding efficiency. Our proposed strategy provides an avenue for fabricating high-performance epoxy nanocomposites.

5.
Ann Intensive Care ; 12(1): 110, 2022 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-36469159

RESUMO

BACKGROUND: The ratio of SpO2/FiO2 to respiratory rate (ROX) index is commonly used to predict the failure of high-flow nasal cannula. However, its predictive power for noninvasive ventilation (NIV) failure is unclear. METHODS: This was a secondary analysis of a multicenter prospective observational study, intended to update risk scoring. Patients with de novo acute respiratory failure were enrolled, but hypercapnic patients were excluded. The ROX index was calculated before treatment and after 1-2, 12, and 24 h NIV. Differences in predictive power for NIV failure using the ROX index, PaO2/FiO2, and PaO2/FiO2/respiratory rate were tested. RESULTS: A total of 1286 patients with de novo acute respiratory failure were enrolled. Of these, 568 (44%) experienced NIV failure. Patients with NIV failure had a lower ROX index than those with NIV success. The rates of NIV failure were 92.3%, 70.5%, 55.3%, 41.1%, 35.1%, and 29.5% in patients with ROX index values calculated before NIV of ≤ 2, 2-4, 4-6, 6-8, 8-10, and > 10, respectively. Similar results were found when the ROX index was assessed after 1-2, 12, and 24 h NIV. The area under the receiver operating characteristics curve was 0.64 (95% CI 0.61-0.67) when the ROX index was used to predict NIV failure before NIV. It increased to 0.71 (95% CI 0.68-0.74), 0.74 (0.71-0.77), and 0.77 (0.74-0.80) after 1-2, 12, and 24 h NIV, respectively. The predictive power for NIV failure was similar for the ROX index and for the PaO2/FiO2. Likewise, no difference was found between the ROX index and the PaO2/FiO2/respiratory rate, except at the time point of 1-2 h NIV. CONCLUSIONS: The ROX index has moderate predictive power for NIV failure in patients with de novo acute respiratory failure.

6.
Artigo em Inglês | MEDLINE | ID: mdl-36472738

RESUMO

Hydrothermal treatment (HT) is envisaged as a promising technology to treat the lignocellulosic biomass. HT temperature is an important parameter influencing the hydrolysate compositions such as organic compounds and potential inhibitors, and therefore affect the subsequential anaerobic digestion (AD) process. Herein, HT-AD was employed to treat the wheat straw-derived digestate. The HT temperature of 190 °C was proved to be the best performance with a higehst reducing sugar yield (45.05 mg g-1) in the hydrolysate and a highest methane yield (120.8 mL gTS-1) from the AD of the hydrolysate, which was 42.5% higher than the methane yield in the control without the hydrolysate addition (84.8 mL gTS-1). 3-Furaldehyde was the dominant organic in the hydrolysates. The HT temperature of 210 °C led to the presence of AD inhibitory moieties (e.g., phenols and furans) in the hydrolysate, resulting in a low methane yield. Although the treatments with the addition of 100% hydrolysate outperformed those of 50% hydrolysate in the methane yields in the late stage, the latter had higher methane yields in the first stage, suggesting that the additional ratios of hydrolysates should be carefully considered in AD, especially the detrimental effects of inhibitors and adaptability issues of AD consortia. The MiSeq sequencing showed that the hydrolysis/acidogenesis was dominant in the first stage, while methanogenesis became dominant in the late stage with the acetoclastic/hydrogenotrophic methanogens (Methanosarcina and Methanobacterium) enriched in the hydrolysate-feeding reactors. These findings demonstrated that a integration of HT-AD was a promising approach for the digestate valorization and to reduce the potential carbon emission from waste treatments.

7.
Adv Mater ; : e2208640, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36457170

RESUMO

Charge-governed ion transport is the vital property of nanofluidic channels for salinity-gradient energy harvesting and other electrochemical energy conversion technologies. Two-dimensional nanofluidic channels constructed by nanosheets exhibit great superiority in ion selectivity, but a high ion transport rate remains challenging due to the insufficiency of intrinsic surface charge density in nanoconfinement. Herein, we demonstrate extrinsic surface charge into nanofluidic channels composed of surfactant-assisted sulfonated covalent organic nanosheets (SCONs), which enable tunable ion transport behaviors. The polar moiety of surfactant is embedded in SCONs to adjust in-plane surface charges, and the aggregation of non-polar moiety results in the sol-to-gel transformation of SCON solution for membrane fabrication. The combination endows SCON/surfactant membranes with considerable water-resistance, and the designable extrinsic charges promise fast ion transport and high ion selectivity. Additionally, the SCON/surfactant membrane, serving as a power generator, exhibits huge potential in harvesting salinity-gradient energy where corresponding output power density can reach up to 9.08 W m-2 under a 50-fold salinity gradient (0.5 M NaCl|0.01 M NaCl). The approach to extrinsic surface charge provides new and promising insight into regulating ion transport behaviors. This article is protected by copyright. All rights reserved.

8.
Angew Chem Int Ed Engl ; : e202212120, 2022 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-36329000

RESUMO

Biological ion channels existing in organisms are critical for many biological processes. Inspired by biological ion channels, the heterogeneous electrospinning nanofiber membranes (HENM) with functional ion channels are constructed by electrospinning technology. The HENM successfully realizes ion-gating effects, which can be used for tunable energy conversions. Introduction of pyridine and carboxylic acid groups into the HENM plays an important role in generating unique and stable ion transport behaviors, in which gates become alternative states of open and close, responding to symmetric/asymmetric pH stimulations. Then we used the HENM to convert osmotic energy into electric energy which reach a maximum value up to 12.34 W m-2 and the output power density of HENM-based system could be regulated by ion-gating effects. The properties of the HENM provide widespread potentials in application of smart nanofluidic devices, energy conversion, and water treatment.

9.
Proc Natl Acad Sci U S A ; 119(49): e2211458119, 2022 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-36442101

RESUMO

Natural structural materials typically feature complex hierarchical anisotropic architectures, resulting in excellent damage tolerance. Such highly anisotropic structures, however, also provide an easy path for crack propagation, often leading to catastrophic fracture as evidenced, for example, by wood splitting. Here, we describe the weakly anisotropic structure of Ginkgo biloba (ginkgo) seed shell, which has excellent crack resistance in different directions. Ginkgo seed shell is composed of tightly packed polygonal sclereids with cell walls in which the cellulose microfibrils are oriented in a helicoidal pattern. We found that the sclereids contain distinct pits, special fine tubes like a "screw fastener," that interlock the helicoidal cell walls together. As a result, ginkgo seed shell demonstrates crack resistance in all directions, exhibiting specific fracture toughness that can rival other highly anisotropic natural materials, such as wood, bone, insect cuticle, and nacre. In situ characterization reveals ginkgo's unique toughening mechanism: pit-guided crack propagation. This mechanism forces the crack to depart from the weak compound middle lamella and enter into the sclereid, where the helicoidal cell wall significantly inhibits crack growth by the cleavage and breakage of the fibril-based cell walls. Ginkgo's toughening mechanism could provide guidelines for a new bioinspired strategy for the design of high-performance bulk materials.


Assuntos
Fraturas Ósseas , Ginkgo biloba , Sementes , Parede Celular , Madeira
10.
Artigo em Inglês | MEDLINE | ID: mdl-36448826

RESUMO

Strong adhesion of hydrogels on solids plays an important role in stable working for various practical applications. However, current hydrogel adhesion suffers from poor interfacial bonding with solid surfaces. Here, we propose a general superwetting-assisted interfacial polymerization (SAIP) strategy to robustly anchor hydrogels onto solids by forming high-density interfacial covalent bonds. The key of our strategy is to make the initiator fully contact solid surfaces via a superwetting way for enhancing the interfacial grafting efficiency. The designed anchored hydrogels show strong bulk failure with a high breaking strength of ~ 1.37 MPa, different from weak interfacial failure that occurs in traditional strategies. The strong interfacial adhesion greatly enhances the stability of hydrogels against swelling destruction. This work opens up new inspirations for designing strongly anchored hydrogels from an interfacial chemistry perspective.

11.
Biomater Sci ; 10(24): 7032-7041, 2022 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-36318065

RESUMO

Due to their homing effects, cell and cell membrane-derived nanocarriers have been widely used to enhance drug target delivery. Inspired by the protein-anchored cell membrane architecture, we here report a tumor-targeted liposome, dtDLP, which was constructed through the electrostatic interaction between dendritic lipopeptide liposomes and a dual-targeted recombinant protein, achieving superior tumor homing, cellular endocytotic and penetration abilities. The dual-targeted recombinant protein consists of an anti-epidermal growth factor receptor single domain antibody and a peptide ligand for the integrin αvß3. dtDLPs substantially reduced macrophage phagocytosis and increased drug internalization in both 4T1 cells and HeLa cells by providing more endocytic pathways. In addition, the dtDLPs showed great penetration ability in both multicellular spheroids and tumor tissues. Due to the improved cancer cellular uptake and tumor penetration, the dtDLPs exhibited a superior anticancer effect in both HeLa and 4T1 tumor-bearing mice. This work will be helpful for the design of cell-specific liposomes with admirable tumor targeting, endocytotic and penetration abilities.

12.
J Air Waste Manag Assoc ; 72(12): 1463-1476, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36319091

RESUMO

An unmanned aerial vehicle equipped with an isokinetic sampling device and a portable aerosol particle size spectrometer was used to detect atmospheric particles at different altitudes in the suburbs of Tianjin. In January 2017, four flight tests under different air conditions were conducted, and the Severe polluted and Excellent levels were classified according to the air quality index of the State-controlled site. Changes in mass concentration with altitude, and the vertical distribution of mass concentration and number concentration spectrum were analyzed. Results showed that under the Severe polluted condition, the concentration of particulate matter (PM) decreased significantly within 200 m, and became stable above 400 m. Two peaks at 260 m and 400 m were observed - they were attributed to local emissions and transportation of nearby areas. When the mass concentration significantly increased, the greatest contributor was particles with a size of 15-30 µm. As altitude increased, PM with the size of less than 1 µm accounted for the largest proportion. Regarding number concentration, the main particle size was less than 0.35 µm. Under the Excellent condition, particles less than 0.35 µm in size were the most important components in mass and number concentrations. Correlation analysis of meteorological factors and backward trajectory indicated that pollution was caused by particle concentration transport in several provinces and the particle accumulation due to temperature inversion.Implications: Study on the vertical structure of air pollutants was very important for understanding the occurrence and development of regional heavy pollution. Unmanned aerial vehicles (UAVs) was an efficient method for its easy operation, good stability, high flexibility and safety, and was introduced to observe the vertical distribution characteristics of particle concentration under different weather conditions. This study provided the number concentration spectra and the mass concentration spectra at different height, and would give some support for the precise control of air pollution.

13.
Nat Commun ; 13(1): 7340, 2022 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-36446803

RESUMO

Titanium carbide MXene combines high mechanical and electrical properties and low infrared emissivity, making it of interest for flexible electromagnetic interference (EMI) shielding and thermal camouflage film materials. Conventional wisdom holds that large MXene is the preferable building block to assemble high-performance films. However, the voids in the films comprising large MXene degrade their properties. Although traditional crosslinking strategies can diminish the voids, the electron transport between MXene flakes is usually disrupted by the insulating polymer bonding agents, reducing the electrical conductivity. Here we demonstrate a sequential densification strategy to synergistically remove the voids between MXene flakes while strengthening the interlayer electron transport. Small MXene flakes were first intercalated to fill the voids between multilayer large flakes, followed by interfacial bridging of calcium ions and borate ions to eliminate the remaining voids, including those between monolayer flakes. The obtained MXene films are compact and exhibit high tensile strength (739 MPa), Young's modulus (72.4 GPa), electrical conductivity (10,336 S cm-1), and EMI shielding capacity (71,801 dB cm2 g-1), as well as excellent oxidation resistance and thermal camouflage performance. The presented strategy provides an avenue for the high-performance assembly of other two-dimensional flakes.

14.
Environ Toxicol Pharmacol ; 97: 104016, 2022 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-36435387

RESUMO

Terbuthylazine is an effective and widely used s-triazine herbicide. However, limited data exists on its toxicity and bioaccumulation in earthworms (Eisenia fetida). In this study, we investigated the bioaccumulation, antioxidant enzyme activity, detoxification enzyme activity, and DNA damage in earthworms when exposed to terbuthylazine. The results indicated that terbuthylazine in soil had low bioaccumulation in earthworms and the biota-soil accumulation factors of terbuthylazine declined with an increasing soil terbuthylazine concentration. In the enzyme activity assays, the superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST) activities showed upward trends when compared with the control. The carboxylesterase (CarE) activity increased on day 21. The 8-hydroxy-2-deoxyguanosine (8-OHdG) content, a DNA damage bioindicator, was higher than that of the control on day 21. Combined with the integrated biological response index version 2 analysis, these results can provide a comprehensive evaluation of the toxicological effects that terbuthylazine has on earthworms and soil ecosystems.

15.
Nucl Med Commun ; 43(12): 1233-1238, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36345768

RESUMO

OBJECTIVE: Endometrial cancer (EC) is the most common invasive gynecological malignancy. This study aimed to retrospectively analyze the relationship between 18F-fluorodeoxyglucose (18F-FDG) PET/computed tomography (CT) parameters and clinicopathological factors in EC patients, and assess whether 18F-FDG PET/CT can be applied for predicting the expressed status of histologic molecular markers. METHODS: Pretreatment clinicopathological characteristics and 18F-FDG PET/CT parameters of maximum standard uptake value (SUVmax), metabolic tumor volume and total lesion glycolysis of primary lesion (MTV-P and TLG-P), and combination of primary lesion and metastases (MTV-C and TLG-C) were retrospectively reviewed in 101 patients with EC. RESULTS: The median age of these 101 patients was 55 years (range, 35-85 years), and 95 patients (94.1%) presented with abnormal vaginal bleeding, 26 patients (25.7%) with elevated serum cancer antigen 125 (CA-125) and 46 patients (45.5%) with increased human epididymis protein 4 (HE4). Sixty-nine cases were at International Federation of Gynecology and Obstetrics (FIGO) stage I, eight at stage II, 20 at stage III, and four at stage IV. FDG uptake was avid in all cases, and the median SUVmax, MTV-P, TLG-P, MTV-C, and TLG-C were 12.9 (range, 2.8-34.2), 8.1 (range, 0.9-547.8), 52.2 (range, 2.5-4420.6), 8.2 (range, 0.9-790.3), and 58.4 (range, 2.5-6972.2), respectively. Estrogen receptor (ER) and progesterone receptor (PR) positive expressions were in 93.1% (94/101) and 90.1% (91/101) patients, respectively. The median Ki-67 index of 101 cases was 40% (range, 0-95%). P53 pattern was tested in 89 patients and 24 cases were mutant type (27.0%). Mesenchymal-epithelial transition factor (c-Met) expression was investigated in 86 patients, and the positivity was in 36 patients (41.9%). Higher PET/CT metabolic parameters were observed in patients with elevated CA-125 and HE4, advanced FIGO stage and higher Ki-67 index (P < 0.05), but had no association with ER/PR expression, P53 pattern, and c-Met expression (P > 0.05). CONCLUSION: FDG uptake in EC was associated with serum CA-125 and HE4, FIGO stage, and Ki-67 index, but no correlations were found between glucose metabolism and ER/PR, P53, and c-Met.


Assuntos
Neoplasias do Endométrio , Fluordesoxiglucose F18 , Feminino , Humanos , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Fluordesoxiglucose F18/metabolismo , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Estudos Retrospectivos , Antígeno Ki-67/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Tomografia Computadorizada por Raios X , Carga Tumoral , Neoplasias do Endométrio/patologia , Glicólise , Prognóstico , Compostos Radiofarmacêuticos
16.
Exp Ther Med ; 24(6): 728, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36382093

RESUMO

Blood-brain barrier (BBB) damage is closely related to morbidity and mortality in patients with traumatic brain injury (TBI). Inhibition of VEGF effectively protects BBB integrity in clinical ischemic stroke. Protecting BBB integrity, reducing brain edema and alleviating post-TBI secondary brain injury are key to a favorable patient prognosis. MMP-9 affects BBB integrity by destroying the tight junction of vascular endothelial cells and inhibiting the transport and enzymatic systems. The present study aimed to examine the possible interplay between VEGF and MMP-9 in TBI. A TBI model was established in 87 male Sprague-Dawley rats. Reverse transcription-quantitative PCR, western blotting, wet-dry brain edema assessment, TUNEL and Fluoro-Jade C staining were performed to analyze the brain tissue samples of the rats. The results showed that compared with in the Sham group rats, the mRNA and protein expression levels of VEGF and MMP-9 were increased at 24 h post-TBI. After bevacizumab treatment, BBB permeability and nerve cell apoptosis were markedly reduced. In conclusion, the present study revealed a potential role for TBI-associated VEGF and MMP-9 upregulation in BBB disruption and nerve damage post-TBI.

17.
Chem Sci ; 13(42): 12309-12325, 2022 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-36382296

RESUMO

Continuous efforts to produce functional nanomaterials and flexible/stretchable devices have promoted cumbersome, laboratorial, detection processes toward wearable and portable intelligent sensing approaches. Responding to the challenges of the multiple analytes, mixtures, and complex components of practical samples, sensing array and multivariate analysis techniques have a significant advantage in terms of superior analytical capabilities, i.e., they are convenient, rapid, sensitive and have high-throughput for multi-analyte identification in food safety, clinical diagnoses, and environmental monitoring. Besides traditional molecular design and recognition mechanisms, materials with micro/nano structures also contribute to strong signals, sensitive responses, and novel properties. In this review, through a new perspective of signal amplification for responsive discrimination, we summarize progress in developing sensing arrays based on diverse micro/nanomaterials and their integrated devices for multi-analyte discrimination. An overview of strategies for constructing sensing arrays through various micro or nano building blocks, including 0D nanoparticle assembly and modification, 1D nanowires and fibers, 2D graphene and textiles, is schematized. Then, portable and wearable devices integrating colorimetric sensors or flexible electrochemical electrodes with the newest microelectronic units and circuit boards are presented. Meanwhile, the latest artificial intelligence (AI) algorithms are introduced for massive data analysis in complex biological and environmental systems. With future developments in facile and accurate discrimination for multi-analyte research, extended applications will gear up in various fields.

18.
Adv Mater ; : e2208413, 2022 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-36428268

RESUMO

Underoil adhesives are intensively needed in case of oil spill caused by pipeline rupture, but remain a challenge owing to the obstruction of oil layer or their swelling in oil. Herein, we demonstrate a general solvent diffusion principle by introducing dual-soluble "mediator" solvents to develop a new type of interfacial instability-induced (3I) adhesives, achieving effective underoil adhesion on various substrates and blocking the oil leakage within seconds. Microscopic characterization reveals a fast and dynamic solvent exchange process that destroys the oil layer by liquid-liquid interfacial diffusion between "mediator" solvents and oil, enabling 3I adhesives to contact solid surfaces directly. The principle of interfacial instability-induced liquid replacement is quite different from typical immiscible liquid replacement and is not restricted by the surface tension of solvents, surface energy and roughness of solid surfaces, successfully directing the construction of a series of effective 3I adhesives with commercially available feedstocks. This study provides a unique clue for the design of next-generation adhesives in complex environments. This article is protected by copyright. All rights reserved.

19.
Nat Mater ; 21(12): 1357-1365, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36357689

RESUMO

The hygroscopic deformation of pine cones, featured by opening and closing their scales depending on the environmental humidity, is a well-known stimuli-responsive model system for artificial actuators. However, it has not been noted that the deformation of pine cones is an ultra-slow process. Here, we reveal that vascular bundles with unique parallelly arranged spring/square microtubular heterostructures dominate the hygroscopic movement, characterized as ultra-slow motion with the outer sclereids. The spring microtubes give a much larger hygroscopic deformation than that of the square microtubes along the longitudinal axis direction, which bends the vascular bundles and consequently drives the scales to move. The outer sclereids with good water retention enable the vascular-bundle-triggered deformation to proceed ultra-slowly. Drawing inspiration, we developed soft actuators enabling controllable yet unperceivable motion. The motion velocity is almost two orders of magnitude lower than that of the same-class actuators reported, which made the as-developed soft actuators applicable in camouflage and reconnaissance.


Assuntos
Movimento , Cone de Plantas , Molhabilidade , Modelos Biológicos
20.
Macromol Rapid Commun ; : e2200806, 2022 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-36444920

RESUMO

Thermoset polymers cross-linked by dynamic covalent bonds are recyclable and reconfigurable based on solid-state plasticity, resulting in less waste and environmental pollution. However, most thermoset polymers previously reported showed thermal-responsive solid-state plasticity, depending much on external conditions and not allowing for local shape modulation. Here, the isocyanate modified carbon nanotubes (CNTs-NCO) was introduced into the polythiourethane (PCTU) network with multiple dynamic covalent bonds by in situ polymerization to prepare the composite with thermal/light dual-responsive solid-state plasticity, reconfigurability, and recyclability. The introduction of CNTs-NCO simultaneously strengthened and toughened the PCTU composite. Moreover, based on the photothermal properties and light-responsive solid-state plasticity, the PCTU/CNTs composite or bilayer sample could achieve complex permanent shape by locally precise shape regulation without affecting other parts. This work provides a simple and reliable method for preparing high-performance polymer composite with light-responsive solid-state plasticity, which may be applied in the fields of sensing and flexible electronics. This article is protected by copyright. All rights reserved.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...