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1.
Artigo em Inglês | MEDLINE | ID: mdl-38949986

RESUMO

Background: Lung adenocarcinoma (LUAD) remains heterogeneous in the prognosis of patients; oxidative stress (OS) has been widely linked to cancer progression. Therefore, it is necessary to explore the prognostic value of the OS-associated genes in LUAD. Methods: An OS-associated prognostic signature was developed using the Cox regression and random forest model in The Cancer Genome Atlas-LUAD dataset. Kaplan-Meier (K-M) survival curve and time-dependent receiver operating characteristic (tROC) curves were applied to evaluate and validate the predictive accuracy of this signature among the training and testing cohorts. A nomogram was constructed and also verified by the concordance index (C-index), calibration curves, and tROC curves, respectively. ESTIMATE algorithm and CIBERSORT algorithms were conducted to explore the signature's immune characteristics. Core target genes of the prognostic signature were identified in the protein-protein interaction network. Results: A six OS-associated prognostic gene signature (CDC25C, ERO1A, GRIA1, TERT, CAV1, BDNF) was developed. The tROC and K-M survival curves in the training and testing cohorts revealed that the signature had good and robust predictive capability to predict the overall survival of LUAD patients. Meanwhile, the risk score was an independent prognostic factor influencing patients' overall survival. The results of the C-index (0.714), calibration curves, and the 1-, 2-, and 3-year tROC curves (area under the curve = 0.703, 0.737, and 0.723, respectively) suggested that the nomogram had good predictive efficacy and prognostic value for LUAD. Then, the authors found that the high-risk group may be depletion or loss of antitumor function of immune cells. Finally, 10 core genes of the signature were predicted. Conclusion: Their study may provide a novel understanding for the identification of prognostic stratification in LUAD patients, as well as the regulation of OS-associated genes in LUAD progression.

2.
Heliyon ; 10(12): e32876, 2024 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-38975175

RESUMO

Introduction: The high incidence of wasp stings have been causing a variety of injuries in China, but systemic complications are rarely reported. Case presentation: A 59-year-old man was severely attacked by wasps. He developed an acute onset of right hemiplegia and chest distress and was admitted to our emergency department 13 hours after being attacked. Various abnormal signals were found by biochemical tests. Magnetic resonance venography of head demonstrated that the superior sagittal sinus was not visible, indicating cerebral venous sinus thrombosis. Magnetic resonance imaging showed abnormal signals in the left frontal lobe, parietal lobe, and thalamus, indicating venous cerebral infarction and hemorrhage, coupled with subarachnoid hemorrhage. The patient was diagnosed with a rare combination of cerebral venous sinus thrombosis, cerebral venous infarction, and multi-organ dysfunction following hornet stings. After undergoing systematic treatment including blood perfusion, blood dialysis, anti-inflammatory hormone therapy, antiallergic medication, antibiotic use, and anticoagulation treatment, the patient showed significant improvement in limb muscle strength and dizziness symptoms. However, the patient developed irreversible kidney damage and is currently dependent on renal replacement therapy. Conclusions: This case highlights the serious systemic consequences that can occur following multiple wasp stings, including rare complications such as venous sinus thrombosis leading to cerebral infarction and renal failure. Early intervention with blood perfusion, hemodialysis, and plasmapheresis, in addition to general treatment, may help prevent permanent organ damage in patients with a large number of wasp stings.

3.
J Colloid Interface Sci ; 669: 23-31, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38703579

RESUMO

Although ordered porous carbon materials (PCMs) have shown promising potential in the field of electromagnetic wave absorption (EWA), creating multifunctional PCMs with outstanding microwave absorption performance remains a significant challenge. Herein, ordered porous carbon aerogels loaded with pea-pod-like nitrogen-doped carbon nanotubes (CNTs) were fabricated via orientation freeze-drying followed by high-temperature pyrolysis. The optimized aerogel exhibits extraordinary EWA performance with a broad effective absorption bandwidth of 7.68 GHz and exceptionally strong absorption of -91.58 dB at a low filling ratio of only 3 wt%, which is the largest absorption strength among all known aerogels to date. The exceptional EWA performance is attributed to the synergistic effect of abundant loss mechanisms resulting from a unique pod-like structure in ordered porous carbon aerogel, where nitrogen-doped CNTs encapsulate magnetic alloy nanoparticles. Optimized aerogel exhibits superior compressive elasticity, thermal insulation, and light weight, laying the groundwork for designing practical next-generation EWA materials.

4.
Angew Chem Int Ed Engl ; 63(28): e202404123, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38702953

RESUMO

One challenge confronting the Cu2O catalysts in the electrocatalysis of carbon dioxide reduction reaction (CO2RR) is the reduction of active Cu(I) species, resulting in low selectivity and quick deactivation. In this study, we for the first time introduce a bottom-up growth of convex sphere with adjustable Cu(0)/Cu(I) interfaces (Cux@Cu2O convex spheres). Interestingly, the interfaces are dynamically modulated by varying hydrothermal time, thus regulating the conversion of C1 and C2 products. In particular, the 4 h hydrothermal treatment applied to Cu0.25@Cu2O convex sphere with the favorable Cu(0)/Cu(I) interface results in the highest selectivity for C2 products (90.5 %). In situ Fourier-transform infrared spectroscopy measurements and density functional theory calculations reveal that the Cu(0)/Cu(I) interface lowers the energy barrier for the production of ethylene and ethanol while increasing the coverage of localized *CO adsorbate for increased dimerization. This work establishes a novel approach for transforming the state of valence-sensitive electrocatalysts into high-value energy-related engineering products.

5.
Open Med (Wars) ; 19(1): 20230887, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38221930

RESUMO

Infection following inguinal hernia repair (IHR) is uncommon. Rational use of antibiotics can significantly improve the prognosis of patients. However, accurately identifying the pathogen involved is usually challenging. This case report describes a patient who developed intermittent fever after undergoing open preperitoneal tension-free repair of a bilateral inguinal hernia. The scrotal fluid specimen was cultured and subjected to metagenomic next-generation sequencing (mNGS). Culture revealed the presence of Enterococcus faecalis (a facultative anaerobe). However, mNGS detected E. faecalis along with multiple anaerobic bacteria including Bacteroides thetaiotaomicron, Parabacteroides distasonis, and Levyella massiliensis. The patient was finally diagnosed with a mixed infection of E. faecalis and multiple anaerobes, and his condition was effectively controlled after timely adjustment of the antibiotic regimen. Treating postoperative infections with multiple concurrent conditions can be challenging. mNGS is valuable for the accurate diagnosis and treatment of infections, as it not only can further verify the culture results, but also assist clinicians in ruling out pulmonary infection caused by hematogenous dissemination after IHR in patients.

6.
Mol Plant Pathol ; 25(1): e13414, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38279852

RESUMO

Fusarium sacchari is one of the primary pathogens causing pokkah boeng disease, which impairs the yield and quality of sugarcane around the world. Understanding the molecular mechanisms of the F. sacchari effectors that regulate plant immunity is of great importance for the development of novel strategies for the persistent control of pokkah boeng disease. In a previous study, Fs00367 was identified to inhibit BAX-induced cell death. In this study, Fs00367nsp (without signal peptide) was found to suppress BAX-induced cell death, reactive oxygen species bursts and callose accumulation. The amino acid region 113-142 of Fs00367nsp is the functional region. Gene mutagenesis indicated that Fs00367 is important for the full virulence of F. sacchari. A yeast two-hybrid assay revealed an interaction between Fs00367nsp and sugarcane ScPi21 in yeast that was further confirmed using bimolecular fluorescence complementation, pull-down assay and co-immunoprecipitation. ScPi21 can induce plant immunity, but this effect could be blunted by Fs00367nsp. These results suggest that Fs00367 is a core pathogenicity factor that suppresses plant immunity through inhibiting ScPi21-induced cell death. The findings of this study provide new insights into the molecular mechanisms of effectors in regulating plant immunity.


Assuntos
Fusarium , Saccharum , Proteína X Associada a bcl-2/metabolismo , Proteína X Associada a bcl-2/farmacologia , Imunidade Vegetal/genética , Saccharum/genética , Saccharum/metabolismo , Morte Celular , Doenças das Plantas
7.
Pediatr Res ; 95(3): 809-818, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37845526

RESUMO

BACKGROUND: Inequalities in job opportunities and income prompts many Chinese parents to leave rural regions to work in urban regions. Their children are left behind in rural regions, subjected to worse quality of childcare that jeopardizes their development. This study aimed to examine the association between quality of childcare and delayed child development in under-three years children left behind in China. METHODS: Cross-sectional national survey was conducted in children left behind in rural China in 2017. Exploratory and confirmatory factor analysis was used to develop a quality of childcare index. Mutlilevel analyses determined factors associated with quality of childcare and child development on a province and individual level. RESULT: The largest population of at-risk children left behind were found in higher-GDP provinces. Children left behind had the lowest mean quality of childcare score. Multilevel analysis found that province level accounted for a great proportion of variance observed. CONCLUSIONS: While migration to urban regions for work may improve household income, a trade-off in worse quality of childcare and developmental delays exists. With improving household income often being the greatest contributing factor for parental migration, policies to reduce inequalities in job opportunities and wealth between rural and urban regions are required. IMPACT: Previous studies identified higher prevalence of developmental delays in children left behind in China. However, quality of childcare has not been examined. Based on WHO's Nurturing Care Framework, we developed a quality of childcare index to assess its association with child development in children left behind. Greatest proportion of children left behind at-risk of developmental delays resided in higher-GDP states, indicating a trade-off in worse quality of childcare and developmental delays. Since improving household income is the main factor for parental migration, policies to close inequalities in job opportunities and wealth between rural and urban regions are required.


Assuntos
Cuidado da Criança , Desenvolvimento Infantil , Criança , Humanos , Estudos Transversais , Renda , China/epidemiologia , População Rural
8.
Microbiol Spectr ; 11(6): e0145223, 2023 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-37962343

RESUMO

IMPORTANCE: Common fungal extracellular membrane (CFEM) domain-containing protein has long been considered an essential effector, playing a crucial role in the interaction of pathogens and plant. Strategies aimed at understanding the pathogenicity mechanism of F. sacchari are eagerly anticipated to ultimately end the spread of pokkah boeng disease. Twenty FsCFEM proteins in the genome of F. sacchari have been identified, and four FsCFEM effector proteins have been found to suppress BCL2-associated X protein-triggered programmed cell death in N. benthamiana. These four effector proteins have the ability to enter plant cells and inhibit plant immunity. Furthermore, the expression of these four FsCFEM effector proteins significantly increases during the infection stage, with the three of them playing an essential role in achieving full virulence. These study findings provide a direction toward further exploration of the immune response in sugarcane. By applying these discoveries, we can potentially control the spread of disease through techniques such as host-induced gene silencing.


Assuntos
Proteínas Fúngicas , Proteínas de Membrana , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Virulência , Imunidade Vegetal , Doenças das Plantas/microbiologia
9.
Dalton Trans ; 52(41): 15057-15070, 2023 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-37812395

RESUMO

Although microstructure optimization is an effective strategy to improve and regulate electromagnetic wave (EMW) absorption properties, preparing microwave absorbents with enhanced EMW absorbing performance and tuned absorption band by a simple method remains challenging. Herein, ZnIn2S4/reduced graphene oxide (rGO) composites with flower-like and cloud-like morphologies were fabricated by a convenient hydrothermal method. The ZnIn2S4/rGO composites with different morphologies realize efficient EMW absorption and tunable absorption bands, covering a wide frequency range. The flower-like structure has an optimal reflection loss (RL) of up to -49.2 dB with a maximum effective absorption bandwidth (EAB) of 5.7 GHz, and its main absorption peaks are concentrated in the C and Ku bands. The minimal RL of the cloud-like structure can reach -36.3 dB, and the absorption peak shifts to the junction of X and Ku bands. The distinguished EMW absorption capacity originates from the uniquely optimized microstructure, complementary effect of ZnIn2S4 and rGO in dielectric constant, and synergy of various loss mechanisms, such as interfacial polarization, dipole polarization, conductive loss, and multiple reflections. This study proposes a guide for the structural optimization of an ideal EMW absorber to achieve efficient and tunable EMW absorption performance.

10.
Materials (Basel) ; 16(17)2023 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-37687694

RESUMO

This study aimed to address the issue of high-temperature challenges in asphalt pavement by developing two types of phase change materials (PCMs) for temperature control. Encapsulated paraffin wax particles (EPWP) and encapsulated myristic acid particles (EMAP) were synthesized using acid-etched ceramsite (AECS) as the carrier, paraffin wax (PW) or myristic acid (MA) as the core material, and a combination of epoxy resin and cement as the encapsulation material. The investigation encompassed leakage tests on PCMs; rutting plate rolling forming tests; SEM, FTIR, XRD, and TG-DSC microscopic tests; as well as heat storage and release tests and temperature control assessments using a light heating device. The study revealed the following key findings. Both types of PCMs exhibited no PCM leakage even under high temperatures and demonstrated low crushing ratios during rut-forming tests. Microscopic evaluations confirmed the chemical stability and phase compatibility of the constituents within the two types of PCMs. Notably, the phase change enthalpies of EPWP and EMAP were relatively high, measuring 133.31 J/g and 138.52 J/g, respectively. The utilization of AECS as the carrier for PCMs led to a substantial 4.61-fold increase in the adsorption rate. Moreover, the PCMs showcased minimal mass loss at 180 °C, rendering them suitable for asphalt pavement applications. The heat storage and release experiments further underscored the PCMs' capacity to regulate ambient temperatures through heat absorption and release. When subjected to light heating, the maximum temperatures of the two types of phase change Marshall specimens were notably lower by 6.6 °C and 4.8 °C, respectively, compared to standard Marshall specimens. Based on comprehensive testing, EPWP displayed enhanced adaptability and demonstrated substantial potential for practical implementation in asphalt pavements.

11.
Cell Mol Biol (Noisy-le-grand) ; 69(5): 105-111, 2023 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-37571893

RESUMO

Sepsis has been characterized as a frequent medical problem with high mortality and severe complication medical problem in the intensive care unit (ICU). Here, qRT-PCR was used to examine circRNA PARG expression levels in patients with sepsis and in human pulmonary microvascular endothelial cells (HPMEC). Lipopolysaccharide (LPS)-simulated HPMEC were hybridized using RNA-Fluorescence in situ hybridization to confirm the location of circRNA PARG and miR-140-3p. The biological role of downregulated circRNA PARGin cellular proliferation, apoptosis, and inflammatory and apoptosis responses was evaluated. performed A dual-luciferase reporter assay was performed to determine the relationship between the circRNA PARG with miR-140-3p. In this study,circRNA PARG aberrant expression was found, and the effects of circRNA PARG on lipopolysaccharide (LPS)-stimulated apoptosis of HPMEC cells were further investigated. Down-regulated circRNA PARG led to significant alleviation of LPS-simulated cell apoptosis via inhibition of inflammatory and apoptosis-related genes, while upregulated circRNA PARG exhibited the opposite effects. Further findings indicated that circRNA PARG positively modulated the relative level of miR-140-3p, which has been confirmed using the luciferase reporter assay. Upregulated circRNA PARG led to a reversal of LPS-simulated cells after transfection of miR-140-3p mimic. In general, a novel insight into understanding the important effects of circRNA PARG in sepsis is provided.


Assuntos
MicroRNAs , Sepse , Humanos , RNA Circular/genética , Células Endoteliais , Hibridização in Situ Fluorescente , Lipopolissacarídeos/farmacologia , Sepse/genética , Apoptose/genética , MicroRNAs/genética
12.
Molecules ; 28(13)2023 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-37446601

RESUMO

Melatonin has profound antioxidant activity and numerous functions in humans as well as in livestock and poultry. Additionally, melatonin plays an important role in regulating the biological rhythms of animals. Combining melatonin with scientific breeding management has considerable potential for optimizing animal physiological functions, but this idea still faces significant challenges. In this review, we summarized the beneficial effects of melatonin supplementation on physiology and reproductive processes in cattle, including granulosa cells, oocytes, circadian rhythm, stress, inflammation, testicular function, spermatogenesis, and semen cryopreservation. There is much emerging evidence that melatonin can profoundly affect cattle. In the future, we hope that melatonin can not only be applied to cattle, but can also be used to safely and effectively improve the efficiency of animal husbandry.


Assuntos
Criação de Animais Domésticos , Cruzamento , Bovinos , Melatonina , Animais , Bovinos/genética , Bovinos/crescimento & desenvolvimento , Bovinos/fisiologia , Criação de Animais Domésticos/métodos , Cruzamento/métodos , Suplementos Nutricionais , Células da Granulosa/efeitos dos fármacos , Células da Granulosa/fisiologia , Melatonina/farmacologia , Melatonina/fisiologia , Oócitos/efeitos dos fármacos , Oócitos/fisiologia , Reprodução/efeitos dos fármacos , Reprodução/fisiologia
13.
J Colloid Interface Sci ; 648: 117-128, 2023 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-37295363

RESUMO

All-weather personal thermal regulation has far been challenged by variable environments especially the regulatory failure caused by highly-dense solar radiation, low environmental radiation and the fluctuated epidermal moisture in different seasons. Herein, from the design of interface selectivity, dual-asymmetrically optical and wetting selective polylactic acid-based (PLA) Janus-type nanofabric is proposed to achieve on-demand radiative cooling and heating as well as sweat transportation. Hollow TiO2 particles are introduced in PLA nanofabric causing high interface scattering (∼99%) and infrared emission (∼91.2%) as well as surface hydrophobicity (CA > 140°). The strictly optical and wetting selectivity help achieve ∼12.8℃ of net cooling effect under > 1500 W/m2 of solar power and ∼5℃ of cooling advantage higher than cotton fabric and sweat resistance simultaneously. Contrarily, the semi-embedded Ag nanowires (AgNWs) with high conductivity (0.245 Ω/sq) endows the nanofabric with visible water permeability and excellent interface reflection for thermal radiation from body (>65%) thus causing ∼7℃ of thermal shielding. Through simple interface flipping, synergistical cooling-sweat reducing and warming-sweat resisting can be achieved to satisfy the thermal regulation in all weather. Compared with conventional fabrics, multi-functional Janus-type passive personal thermal management nanofabrics would be of great significance to achieve the personal health maintenance and energy sustainability.

14.
J Colloid Interface Sci ; 642: 283-291, 2023 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-37004262

RESUMO

Covalent organic frameworks (COFs) are excellent candidates for rationally designed metal-coordinated catalysts due to their porous structures and adjustable organic building blocks. In this work, a two-dimensional (2D) COF with novel fxt topology was synthesized. The newly devised COF had been fully characterized by a range of spectroscopic and microscopic techniques. The COF was further metallized by the gold species to form a heterogeneous catalyst that enabled the one-pot synthesis of flavone and its derivatives. The Au@COF catalyst showed high catalytic activity and good recyclability. This work demonstrates the great potential of metallized COFs with unique well-defined pores in organic catalysis.

15.
Angew Chem Int Ed Engl ; 62(21): e202302997, 2023 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-36943400

RESUMO

Biological ion channels regulate the ion flow across cell membrane via opening or closing of the pores in response to various external stimuli. Replicating the function of high ion gating effects with artificial porous materials has been challenging. Herein, we report that the self-assembled two-dimensional metal-organic framework (MOF) membrane can serve as an excellent nanofluidic platform for smart regulation of ion transport. The MOF membrane with good photothermal performance exhibits extremely high ion gating ratio (up to 104 ), which is among the highest values in MOF membrane nanochannels for light-controlled ion gating reported so far. By repeatedly turning on and off the light, the nanofluidic device shows outstanding stability and reversibility that can be applied in the remote light-switching system. This work may spark promising applications of MOF membrane with variety of stimuli responsive properties in ion sieving, biosensing, and energy conversion.

16.
ACS Appl Mater Interfaces ; 15(13): 16631-16639, 2023 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-36943938

RESUMO

In order to selectively oxidize benzyl alcohol, a novel noble metal catalyst based on polymer ionic liquids with a core-shell structure was created. First, polymer ionic liquid microspheres (PILMs) were prepared by free radical polymerization. Second, the in situ adsorption of Au nanoparticles on the surface of PILMs was accomplished, thanks to the strong electrostatic interaction between N atoms and metal ions on the diazole ring of PILMs. Additionally, the introduction of Al(OH)3 prevented the aggregation of Au nanoparticles and promoted the catalytic reaction. Finally, the PILM/Au/Al(OH)3 catalyst with a core-shell structure was formed. The effectiveness of the PILM/Au/Al(OH)3 catalyst was assessed by varying the catalyst's type, quantity, amount of Au, amount of H2O2, temperature, and reaction time. After five cycles of experiments, the catalyst was effective and reusable. In addition, the potential catalytic mechanism of the catalyst in the oxidation of benzyl alcohol was proposed.

17.
Am J Transl Res ; 15(2): 1017-1025, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36915749

RESUMO

OBJECTIVE: This study aimed to investigate the mechanism of γ-secretase inhibitor (GSI) in myocardial repair in septic rats. METHODS: Thirty-six healthy male Wistar rats were randomly and equally divided into control groups, model group and intervention group. The model group and the intervention group were treated with ligation of cecum and perforation to build sepsis model, and the intervention group received intraperitoneal injection of GSI II (DAPT). Serum levels of Troponin T (cTnT), creatine kinase isoenzyme (CK-MB) and interleukin-17 were measured by ELISA. The Th17 cell percentage in peripheral blood mononuclear cells in CD4+ cells was determined by flow cytometry, and myocardial tissue cells in each group were measured by TUNEL. The mRNA of RORγt was measured by real-time quantitative PCR, and the protein expressions of Notch1, Hes1 and HIF-α in myocardial tissue were measured by Western blot. RESULTS: The cTnT, CK-MB, Th17 and Th17/CD4+ levels in the model group and the intervention group were remarkably higher than those in the control group (P<0.05), while those in the intervention group were remarkably lower than those in the model group (P<0.05). Myocardial apoptosis rate, myocardial RORγt mRNA and protein expressions of Notch1, Hes1 and HIF-α in the model group and the intervention group were obviously higher than those in control group (P<0.05), and those in the intervention group were obvious lower than those in the model group (P<0.05). CONCLUSION: γ secretase inhibitors have clearly protective effects on cardiomyocytes, and the mechanism may be associated with Notch blocking and RORγt expression, which inhibit immune damage induced by abnormal activation of Th17.

18.
Nanoscale ; 15(11): 5230-5240, 2023 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-36825559

RESUMO

Carrier spatial separation efficiency and active electron density are the key factors affecting photocatalytic hydrogen evolution activity. Heterojunction catalysts with fast charge separation and directed electron transport systems were successfully prepared by a synergistic modification strategy of transition metal (Co) doping and crystal plane modulation. The optimized electronic structure and enhanced reaction kinetics enabled unidirectional electron transfer. Photocatalytic results show that CdS(002)/Co-C3N4 exhibits remarkable hydrogen evolution activity (991.2 µmol h-1 g-1) in the absence of a co-catalyst, which is 37.0 and 3.4 times higher than that of C3N4 (26.8 µmol h-1 g-1) and Co-C3N4 (294.6 µmol h-1 g-1), respectively. Density functional theory (DFT) calculations indicate that the enhanced catalytic activity of CdS(002)/Co-C3N4 is attributed to the reduced electron-hole recombination rate and the increased electron density at the active site. This work provides a new idea for the design of photocatalysts with directed charge transport channels from the perspective of re-optimizing heterojunctions.

19.
Dalton Trans ; 52(10): 3085-3096, 2023 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-36786669

RESUMO

In the practical application of microwave absorbing materials, traditional powder materials need to be mixed with the matrix to fabricate composite coatings. However, the complex preparation process of composite coatings and the uneven dispersion of powders in the matrix limit their application. To solve these problems, two-dimensional (2D) F-WS2/CP composite films were prepared by using carbon paper (CP) as a dispersion matrix and loading flower-like WS2 on its surface through a simple hydrothermal method. The morphology and microwave absorption (MA) performance of the composite films are easily regulated by adjusting the amount of reaction precursors. The combination of WS2 and CP facilitates impedance matching and improves the electromagnetic wave attenuation performance based on the synergistic effect of different loss mechanisms including multiple reflections and scattering, interfacial polarization, dipolar polarization, and conduction loss. At a low filler content (5 wt%), the maximum reflection loss (RL) of the composite film is up to -50 dB (99.999% energy absorption) at 12.5 GHz with 2.8 mm thickness. Moreover, at a relatively thin 1.8 mm thickness, its maximum RL remains -35 dB (>99.9% energy absorption). The as-prepared composite film shows excellent MA properties at a thinner thickness and lower filling content, providing inspiration for the preparation of light weight and efficient 2D thin-film microwave absorbers in the future.

20.
Langmuir ; 38(48): 14733-14744, 2022 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-36412147

RESUMO

Although intensive efforts have been devoted to fabricating Ti3C2Tx MXene composites for microwave absorption, it remains a great challenge to achieve excellent MA performance at low loading and thin thickness. Herein, a three-dimensional (3D) lightweight hierarchically structured MnO2/Ti3C2Tx/RGO composite aerogel with abundant heterointerfaces was fabricated via a hydrothermal and chemical reduction self-assembly method. The RGO aerogel embedded with laminated MnO2/Ti3C2Tx provides a lot of heterogeneous interfaces, 3D porous interconnected conductive networks, and reasonable combination of various loss materials for rich interfacial polarization, conductivity loss, multiple reflections and scattering, and good impedance matching. Benefiting from the synergy of different loss mechanisms, the maximum reflection loss (RL) is up to -66.5 dB (>99.9999% energy absorption) at only 10 wt % loading and 2.0 mm thickness, and even at only 1.5 mm thickness, the maximum RL value remains at -36 dB (>99.9% energy absorption). The work provides a promising route to construct 3D hierarchically heterogeneous composite aerogels for efficient MA at thin thickness and low loading.

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