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1.
Quant Imaging Med Surg ; 14(8): 5434-5442, 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-39144007

RESUMO

Background: Extravaginal testicular torsion has profound clinical implications in neonates, but its ultrasound characteristics may vary at different disease stages. The purpose of this study was to identify the ultrasound characteristics of neonatal extravaginal testicular torsion and their diagnostic value at different disease stages. Methods: A retrospective analysis of the clinical and ultrasound examination data of 20 infants aged 1-75 days with surgically and pathologically confirmed unilateral extravaginal testicular torsion (10 right, 10 left) was conducted. The infants were divided into three stages based on the ultrasound characteristics: double-ring effusion, calcification of the tunica vaginalis, and testicular atrophy. Results: In the double-ring effusion stage, the affected testicles were enlarged with axial abnormalities, with the parenchymal testicular blood flow signal significantly reduced or absent. Twisted paratesticular masses and a "double-ring effusion sign" were visible. In the tunica vaginalis calcification stage, the affected testicles were slightly smaller, with axial abnormalities, absent blood flow signals in the testicular parenchyma, and strong echogenicity of the tunica vaginalis. In the testicular atrophy stage, the affected testicles were markedly smaller, with enhanced echogenicity in the tunica vaginalis and parenchyma, and absent blood flow signal in the testicular parenchyma. The volumes of the affected testicles gradually decreased from the stage of double-ring effusion to that of tunica vaginalis calcification, and then to testicular atrophy (P<0.05). Conclusions: Neonatal extravaginal testicular torsion at different disease stages has distinct ultrasound features, and color doppler ultrasound plays an important role in the diagnosis and treatment of extravaginal testicular torsion.

2.
Small ; : e2405874, 2024 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-39206598

RESUMO

Heterogeneous interfacial engineering has garnered widespread attention for optimizing polarization loss and enhancing the performance of electromagnetic wave absorption. A novel Kirkendall effect-assisted electrostatic self-assembly method is employed to construct a metal-organic framework (MOF, MIL-88A) decorated with Ni-Fe layered double hydroxide (LDH), forming a multilayer nano-cage coated with Ti3C2Tx. By modulating the surface adsorption of Ti3C2Tx on LDH, the heterointerfaces in MOF-LDH-MXene ternary composites exhibit excellent interfacial polarization loss. Additionally, the Ni-Fe LDH@Ti3C2Tx nano-cage exhibits a large specific surface area, abundant defects, and a large number of heterojunction structures, resulting in excellent electromagnetic wave absorption performance. The MIL-88A@Ni-Fe LDH@Ti3C2Tx-1.0 nano-cage achieves a reflection loss value of -46.7 dB at a thickness of 1.4 mm and an effective absorption bandwidth of 5.12 GHz at a thickness of 1.8 mm. The heterojunction interface composed of Ni-Fe LDH and Ti3C2Tx helps to enhance polarization loss. Additionally, Ti3C2Tx forms a conductive network on the surface, while the cavity between the MIL-88A core and the Ni-Fe LDH shell facilitates multiple attenuations by increasing the transmission path of internal incident waves. This work may reveal a new structural design of multi-component composites by heterointerfaces engineering for electromagnetic wave absorption.

3.
J Colloid Interface Sci ; 678(Pt A): 648-655, 2024 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-39216392

RESUMO

Electromagnetic wave absorption materials (EWAMs) have become an effective means to address electromagnetic (EM) radiation and enhance stealth technology, among which aerogels are valued for their lightweight nature and excellent designability. This study utilized environmentally friendly preparation and in-situ reduction techniques to fabricate bacterial cellulose (BC) / reduced graphene oxide (RGO) aerogels, achieving tailored EM wave loss capabilities by controlling the reduction time of ascorbic acid. Benefitting from the effects of freeze-casting, BC winding, hydrogen bond, and RGO layers coupling, the aerogel maintains their original structure after reduction and exhibits satisfactory EM wave absorption. The minimum reflection loss (RLmin) is -38.52 dB, with an effective absorption bandwidth (EAB) of 6.68 GHz and a maximum radar cross section (RCS) reduction of 44.69 dBsm. Additionally, the aerogel's lightweight (a low density of 9.03 mg/cm3) and outstanding thermal insulation properties enable it to adapt to complex conditions. Thus, the study provides a novel approach for the construction of industrialized and sustainable RGO-based EWAMs.

4.
Small ; : e2403689, 2024 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-39128133

RESUMO

The excellent performance of electromagnetic wave absorbers primarily depends on the coordination among components and the rational design of the structure. In this study, a series of porous fibers with carbon nanotubes uniformly distributed in the shape of pine leaves are prepared through electrospinning technique, one-pot hydrothermal synthesis, and high-temperature catalysis method. The impedance matching of the nanofibers with a porous structure is optimized by incorporating melamine into the spinning solution, as it undergoes gas decomposition during high-temperature calcination. Moreover, the electronic structure can be modulated by controlling the NH4F content in the hydrothermal synthesis process. Ultimately, the Ni/Co/CrN/CNTs-CF specimen (P3C NiCrN12) exhibited superior performance, while achieving a minimum reflection loss (RLmin) of -56.18 dB at a thickness of 2.2 mm and a maximum absorption bandwidth (EABmax) of 5.76 GHz at a thickness of 2.1 mm. This study presents an innovative approach to fabricating lightweight, thin materials with exceptional absorption properties and wide bandwidth by optimizing the three key factors influencing electromagnetic wave absorption performance.

5.
J Colloid Interface Sci ; 676: 217-226, 2024 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-39024822

RESUMO

Developing multifunctional materials which could simultaneously possess anti-bacterial ability and electromagnetic (EM) absorption ability during medical care is quite essential since the EM waves radiation and antibiotic-resistant bacteria are threatening people's health. In this work, the multifunctional carbon fiber/Ti3C2Tx MXene (CM) were synthesized through repeated dip-coating and following in-situ growth method. The as-fabricated CF/MXene displayed outstanding EM wave absorption and highly efficient photothermal converting ability. The minimum reflection loss (RL) of -57.07 dB and ultra-broad absorption of 7.74 GHz could be achieved for CM composites. By growth of CoNi-layered double hydroxides (LDHs) sheets onto MXene, the absorption bandwidth for carbon fiber/Ti3C2Tx MXene layered double hydroxides (CML) could be reach 5.44 GHz, which could cover the whole Ku band. The excellent photothermal effect endow the CM composites with excellent antibacterial performance. The antibacterials tests indicated that nearly 100 % bactericidal efficiency against E. acoil and S. aureus was obtained for the CM composite after exposure to near-infrared region (NIR) irradiation. This work provides a promising candidate to combat medical device-related infections and EM pollution.


Assuntos
Antibacterianos , Fibra de Carbono , Escherichia coli , Raios Infravermelhos , Staphylococcus aureus , Antibacterianos/farmacologia , Antibacterianos/química , Antibacterianos/síntese química , Staphylococcus aureus/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Fibra de Carbono/química , Radiação Eletromagnética , Testes de Sensibilidade Microbiana , Titânio/química , Titânio/farmacologia , Lasers , Tamanho da Partícula , Propriedades de Superfície
6.
Heliyon ; 10(12): e33145, 2024 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-39022044

RESUMO

CD19 is a surface antigen on B cells that regulates B cell activation and proliferation, participating in B cell signaling. It is expressed in all B cell lineage tumor diseases, making CD19 a significant marker for detecting B cell tumor diseases and an important target for related immunotherapies. In recent years, with the deepening research on canine and feline diseases and the establishment of animal models, the demand for cat CD19 monoclonal antibodies (mAbs) has been steadily increasing. We successfully prepared cat CD19-specific monoclonal antibodies using a KLH-conjugated cat CD19 peptide as an antigen and optimized the antibody production method. The obtained monoclonal antibodies' molecular and cellular affinities were identified using CD19 peptides, eukaryotic overexpressed proteins, and peripheral blood mononuclear cells (PBMCs). The results indicate that the CD19-3H9 and CD19-8A7 monoclonal antibodies prepared in this study specifically bind to the CD19 molecule, demonstrating their suitability for use in ELISA, Western blot, and cell assays. This study successfully produced cat CD19 monoclonal antibodies with specificity and optimized the antibody preparation method, laying the foundation for the diagnosis and targeted drug combination therapy of B cell tumor diseases in both humans and pets.

7.
Small ; : e2404449, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-39011980

RESUMO

Currently, facing electromagnetic protection requirement under complex aqueous environments, the bacterial reproduction and organic dye corrosion may affect the composition and micro-structures of absorbers to weaken their electromagnetic properties. To address such problems, herein, a series of CoFe2O4@BCNPs (cobalt ferrite @ bio-carbon nanoparticles) composites are synthesized via co-hydrothermal and calcining process. The coupling of magnetic cobalt ferrite and dielectric bio-carbon derived from Apium can endow the composite multiple absorption mechanisms and matched impedance for effective microwave absorption, attaining a bandwidth of 8.12 GHz at 2.36 mm and an intensity of -49.85 dB at 3.0 mm. Due to the ROS (reactive oxygen species) stimulation ability and heavy metal ions of cobalt ferrite, the composite realizes an excellent antibacterial efficiency of 99% against Gram negative bacteria of Escherichia coli. Moreover, the loose porous layer of surface stacked bio-carbon can promote the adsorption of methylene blue for subsequent eliminating, a high removal rate of 90.37% for organic dye can be also achieved. This paper offers a new insight for rational design of composite's component and micro-structure to construct multi-functional microwave absorber for satisfying the electromagnetic protection demand in complicated environments.

8.
Int J Biol Macromol ; 273(Pt 1): 133052, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38857732

RESUMO

Scalable and highly efficient bamboo whitening remains a great challenge. Herein, an effective bamboo whitening strategy is proposed based on photocatalyzed oxidation, which involves H2O2 infiltration and UV illumination. The as-prepared white bamboo well maintains the nature structure of natural bamboo and demonstrates high whiteness and superior mechanical properties. The absorbance value is significantly decreased to 3.5 and the transmittance is increased to 0.04 % in UV-visible wavelength range due to the removal of light-absorbing chromospheres of lignin, resulting in a high whiteness when the UV illumination time is 8 h. In addition, the white bamboo displays a high tensile strength of 30 MPa and a high flexural strength of 36 MPa due to the well-preserved lignin units (lignin preservation is about 89 %). XRD patterns and analysis show that photocatalyzed oxidation has no effect on the crystal parameters of cellulose. Compared with the traditional bamboo whitening technology, our photocatalyzed oxidation strategy demonstrates significant advantage including chemical and time conservation, high efficiency, environment friendliness, and mechanical robustness. This highly efficient and environmentally friendly photocatalyzed oxidation strategy for the fabrication of white bamboo may pave the way of bamboo-based energy-efficient structural materials for engineering application.


Assuntos
Lignina , Oxirredução , Lignina/química , Catálise , Sasa/química , Peróxido de Hidrogênio/química , Resistência à Tração , Raios Ultravioleta , Processos Fotoquímicos , Cor , Poaceae/química
9.
Sensors (Basel) ; 24(10)2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38793958

RESUMO

Ion mobility spectrometry (IMS) has been widely studied and applied as an effective analytical technology for the on-site detection of volatile organic compounds (VOCs). Despite its superior selectivity compared with most gas sensors, its limited dynamic range is regarded as a major drawback, limiting its further application in quantitative measurements. In this work, we proposed a novel sample introduction method based on pulsed membrane adsorption, which effectively enhanced IMS's ability to measure analytes at higher concentrations. Taking N-methyl-2-pyrrolidone (NMP) as an example, this new sampling method expanded the dynamic range from 1 ppm to 200 ppm. The working principle and measurement strategy of this sampling method were also discussed, providing new insights for the design and application of IMS-based instruments.

10.
Small ; 20(8): e2305849, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37817350

RESUMO

Layered double hydroxides (LDHs) with unique layered structure and atomic composition are limited in the field of electromagnetic wave absorption (EMA) due to their poor electrical conductivity and lack of dielectric properties. In this study, the EMA performance and anticorrosion of hollow derived LDH composites are improved by temperature control and composition design using ZIF-8 as a sacrifice template. Diverse regulation modes result in different mechanisms for EMA. In the temperature control process, chemical reactions tune the composition of the products and construct a refined structure to optimize the LDHs conductivity loss. Additionally, the different phase interfaces generated by the control components optimize the impedance matching and enhance the interfacial polarization. The results show that the prepared NCZ (Ni3ZnC0.7/Co3ZnC@C) has a minimum reflection loss (RLmin ) of -58.92 dB with a thickness of 2.4 mm and a maximum effective absorption bandwidth (EABmax ) of 7.36 GHz with a thickness of 2.4 mm. Finally, due to its special structure and composition, the sample exhibits excellent anticorrosion properties. This work offers essential knowledge for designing engineering materials derived from metal organic framework (MOF) with cutting-edge components and nanostructures.

11.
Carbohydr Polym ; 321: 121304, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37739534

RESUMO

Fucosylated chondroitin sulfate (FCS) extracted from Phyllophorella kohkutiensis (PkFCS) is composed of d-GalNAc, d-GlcA, l-Fuc and -SO42-. According to the defined structures revealed by NMR spectra of the branches released by mild acid hydrolysis and oligosaccharides generated by ß-eliminative depolymerization, the backbone of PkFCS is CS-E, and the branch types attached to C-3 of d-GlcA include l-Fuc2S4S, l-Fuc3S4S, l-Fuc4S, and the disaccharide α-d-GalNAc-1,2-α-l-Fuc3S4S with the ratio of 43:13:22:22. Notably, novel heptasaccharide and hendecasaccharide were identified that are branched with continuous distribution of the disaccharide. The structural sequences of the oligosaccharides indicate that three unique structural motifs are present in the entire PkFCS polymer, including a motif branched with randomly distributed different sulfated l-Fuc units, a motif containing regular l-Fuc2S4S branches and a motif enriched in α-d-GalNAc-1,2-α-l-Fuc3S4S. This is the first report about the distribution pattern of diverse branches in natural FCS. Natural PkFCS exhibited potent anticoagulant activity on APTT prolonging and anti-iXase activity. Regarding the structurally defined oligosaccharides with sulfated fucosyl side chains, octasaccharide (Pk4b) is the minimum fragment responsible for its anticoagulant activity correlated with anti-iXase. However, further glycosyl modification with a non-sulfated d-GalNAc at the C-2 position of l-Fuc3S4S could significantly decrease the anticoagulant and anti-iXase activity.


Assuntos
Pepinos-do-Mar , Animais , Anticoagulantes/farmacologia , Sulfatos de Condroitina/farmacologia , Dissacarídeos , Sulfatos , Óxidos de Enxofre
12.
Small ; 19(52): e2304932, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37635102

RESUMO

Reasonable composition design and controllable structure are effective strategies for harmonic electromagnetic wave (EMW) adsorption of multi-component composites. On this basis, the hybrid MoS2 /CoS2 /VN multilayer structure with the triple heterogeneous interface is prepared by simple stirring hydrothermal, which can satisfy the synergistic interaction between different components and obtain excellent EMW absorption performance. Due to the presence of multiple heterogeneous interfaces, MoS2 /CoS2 /VN composites will produce strong interfacial polarization, while the defects in the sample will become the center of polarization, resulting in dipole polarization. Due to the excellent structural design of MoS2 /CoS2 /VN composite material, MoS2 /CoS2 /VN composite material not only has good conductive loss and polarization loss, but also can maintain excellent stability in simulated seawater, and enhance corrosion resistance. The MoS2 /CoS2 /VN composite with dual functions of corrosion resistant and microwave absorption achieves a minimum reflection loss (RL) of -50.48 dB and an effective absorption bandwidth of up to 5.76 GHz, covering both the X-band and Ku-band. Finally, this study provides a strong reference for the development of EMW absorption materials based on transition metal nitrides.

13.
J Colloid Interface Sci ; 651: 494-503, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37556906

RESUMO

In the field of electromagnetic (EM) wave absorption, intrinsic conductive polymers with conjugated long-chain structures, such as polyaniline (PANI) and polypyrrole (PPy), have gained widespread use due to their remarkable electrical conductivity and loss ability. However, current research in this area is limited to macroscopic descriptions of the absorption properties of these materials and the contribution of various components to the absorption effect. There has been insufficient exploration of the impact mechanisms of polymer aggregation states on the material's absorption performance and mechanism. To address this, a series of flexible PANI sponge absorbers with different molecular weights and aggregation states were prepared. By carefully controlling the crystallinity and other aggregation characteristics of PANI through the adjustment of its preparation conditions, we were able to influence its electrical conductivity and electromagnetic parameters, thereby achieving control over the material's absorption properties. The resulting PANI sponge absorbers exhibited an effective absorption bandwidth (EAB) that covered the entire X-band at a thickness of 3.2 mm. This study comprehensively explores the absorption mechanisms of conductive polymer absorbers, starting from the microstructure of PANI, and providing a more complete theoretical support for the research and promotion of polymer absorbers.

14.
J Colloid Interface Sci ; 633: 92-101, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36436351

RESUMO

Polyaniline, a modified conductive polymer, has been widely studied in the field of electromagnetic (EM) wave absorption due to its excellent dielectric and conductive properties. However, it has limited applications due to its hard molding and processing, and poor mechanical stability. In this study, ice crystals with rapid directional growth were used as templates for polymerization to obtain polymer precursors with directional channels, and then ternary polymer sponges with oriented pore channels were designed and synthesized using a secondary template method. The Poisson's ratio of the study material reaches -1.52 and it absorbs 5.1 mJ/cm3 energy in a single compression cycle at 25% longitudinal strain. Also, the material has more than 90% absorption efficiency for X-band EM waves at a thickness of 4 mm. The flexibility of polymer molecular chains and the arrangement of oriented pores are the reasons for the negative Poisson's ratio property of the material, while the key to the loss of EM energy in the absorption process is the conversion of quinone bipolaron to monopolaron structure. Due to its large-scale green preparation with ice crystal as the template, this lightweight and robust material system are ideal for absorbing EM waves under extreme conditions.

15.
Carbohydr Polym ; 295: 119855, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-35989002

RESUMO

Peroxidative depolymerization is often used to elucidate the structure and structure-activity relationship of fucosylated glycosaminoglycan (FG), while the selectivity of bond cleavage and structural characteristics of the resulting fragments remain to be confirmed. Here, the FG from Stichopus variegatus (SvFG) was depolymerized by H2O2, and a series of yielded mono- and oligo-saccharides were purified. Almost all the non-reducing ends of oligosaccharides were d-GalNAc4S6S, suggesting that GlcA-ß1,3-GalNAc4S6S linkage was preferentially cleaved. The model reactions showed the glycosidic bond of uronate was more susceptible than those of N-acetyl hexosamine and fucose, which should be due to bond energy of the anomeric CH. The reducing ends of oligosaccharides include C4-C6 saccharic acid and GalNAc or GalNAcA, which should be derived from the oxidation of the reducing end. A hexasaccharide with tartaric acid exhibited increased anti-iXase activity, suggesting the oxidation of reducing end did not impair the anti-iXase activity of FG-derived oligosaccharides.


Assuntos
Glicosaminoglicanos , Peróxido de Hidrogênio , Anticoagulantes/química , Fucose/química , Glicosaminoglicanos/química , Oligossacarídeos/química
16.
Diabetes Metab Syndr Obes ; 15: 2207-2216, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35923250

RESUMO

Background: Better survival for overweight and obese patients after ST-segment elevation myocardial infarction (STEMI) has been demonstrated. The association between body mass index (BMI), microvascular obstruction (MVO), and area at risk (AAR) after STEMI was evaluated. Methods: A prospective observational study was performed to enrolled patients undergoing primary percutaneous coronary intervention (pPCI) for STEMI and cardiac magnetic resonance was performed within 5-7 days. Patients were classified as normal weight (18.5 ≤BMI <24.0 kg/m2), overweight (24.0 ≤BMI <28.0 kg/m2), or obese (BMI ≥28 kg/m2). Results: Among 225 patients undergoing pPCI, 67 (30.00%) were normal weight, 113 (50.22%) were overweight, and 45 (20.00%) were obese. BMI ≥28 kg/m2 was significantly associated with less risk of MVO when compared with a normal BMI after multivariable adjustment (overweight: HR 0.29, 95% CI 0.13-0.68, p = 0.004). Compared with normal weight patients, obese and overweight patients tend to have larger hearts (greater left ventricular end-diastolic volume [LVEDV] and left ventricular [LV] mass). In adjusted analysis, increased BMI was significantly associated with a smaller AAR. In addition, obese patients had a smaller AAR (ß = -0.252, 95% CI -20.298- -3.244, p = 0.007) and AAR, % LV mass (ß = -0.331, 95% CI -0.211- -0.062, p < 0.001) than normal weight patients. Conclusion: Obesity (BMI ≥28 kg/m2) is independently associated with lower risks of MVO and a smaller AAR, % LV mass than normal weight patients among subjects undergoing pPCI for STEMI.

17.
Plant Physiol Biochem ; 182: 227-239, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35526420

RESUMO

Soil salinity is a serious problem encountered by agriculture worldwide, which will lead to many harmful effects on plant growth, development, and even crop yield. F-box protein is the core subunit of the Skp1-Cullin-F-box (SCF) complex E3 ligase and plays crucial roles in regulating the growth, development, biotic & abiotic stresses, as well as hormone signaling pathway in plants. In this study, an FBA type F-box gene TaFBA-2A was isolated from wheat (Triticum aestivum L.). This study showed that TaFBA-2A could interact with TaSKP1, and TaOPR2, the crucial enzyme involving in jasmonic acid (JA) biosynthesis. TaFBA-2A negatively regulates JA biosynthesis, probably by mediating the degradation of TaOPR2 via the ubiquitin-26S proteasome pathway. Ectopic expression of TaFBA-2A improved the salt tolerance and increased the JA responsiveness of the transgenic rice lines. In addition, some agronomic traits closely related to crop yield were significantly enhanced in the rice lines ectopic expressing TaFBA-2A. The data obtained in this study shed light on the function and mechanisms of TaFBA-2A in JA biosynthesis and the responses to salt stress and JA treatment; this study also suggested that TaFBA-2A has the potential in improving the salt tolerance and crop yield of transgenic rice plants.


Assuntos
Proteínas F-Box , Oryza , Ciclopentanos/metabolismo , Proteínas F-Box/genética , Regulação da Expressão Gênica de Plantas , Oryza/genética , Oryza/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Tolerância ao Sal/genética , Estresse Fisiológico/genética , Triticum/metabolismo
18.
J Colloid Interface Sci ; 620: 263-272, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35429705

RESUMO

It has become greatly significant to achieve structurally tunable electromagnetic wave absorption materials (EMAs) derived from metal-organic frameworks (MOFs) via controllably continuous phase inversion. Herein, a series of core-shell Ag@C EMAs were successfully fabricated from Ag-MOFs via adjustable phase inversion. Replacing terephthalic acid (H2BDC) with 2-methylimidazole (Hmim) continuously led to the gradual transformation of Ag-MOF-5 structure into ZIF-L, which determined the crystal and morphological structure of Ag@C EMAs. In addition, due to the optimization of relaxation loss, the minimum reflection loss (RLmin) of S2 reached -50.14 dB with a thickness of 3.0 mm. The EMA derived from the original Ag-MOF had the widest absorption bandwidth (fE) of 5.44 GHz and RLmin of -47.36 dB at only 2.2 mm, respectively. This work can shed new light on the core-shell EMAs derived from phase inversion MOFs, and provide guidance to design novel high-performance EMAs.

19.
J Colloid Interface Sci ; 600: 288-298, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34022725

RESUMO

Various types of polycrystals have been regarded as excellent electromagnetic (EM) microwave absorbents, while differentiated heterointerfaces among grains usually manipulate conductive loss and polarization relaxation, especially interfacial polarization. Herein, polar facets that dominated the optimization of EM attenuation were clarified by carefully designing polycrystalline Schottky junctions with metal-semiconductor contacts for the first time. An ingenious ligand exchange technique was utilized to construct Zn-MOF (ZIF-L) precursors for Fe-ZnO polycrystals, in which Fe-containing Fe(CN)63- etching ligand acted as metallic source in Schottky junctions. By adjusting the Schottky contacts in polycrystals, the enhanced grain boundaries mainly induced stronger interfacial polarization and affected the microcurrent lightly. This is because Schottky barriers can cause local charge accumulation on heterointerfaces for polarization relaxation. Additionally, the coexistence of Zn and O vacancies brought a lot of lattice defects and distortions for dipole polarization. Thus, optimal EM wave absorbability was obtained by polycrystals with 8 h ligand exchange and an effective absorption band reaching 4.88 GHz. This work can provide guidance for designing advanced polycrystalline EM absorption materials and also highlight the mechanism and requirement of Schottky junctions dominating polarization.

20.
Molecules ; 25(15)2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32751631

RESUMO

Nitrated-pyrazole-based energetic compounds have attracted wide publicity in the field of energetic materials (EMs) due to their high heat of formation, high density, tailored thermal stability, and detonation performance. Many nitrated-pyrazole-based energetic compounds have been developed to meet the increasing demands of high power, low sensitivity, and eco-friendly environment, and they have good applications in explosives, propellants, and pyrotechnics. Continuous and growing efforts have been committed to promote the rapid development of nitrated-pyrazole-based EMs in the last decade, especially through large amounts of Chinese research. Some of the ultimate aims of nitrated-pyrazole-based materials are to develop potential candidates of castable explosives, explore novel insensitive high energy materials, search for low cost synthesis strategies, high efficiency, and green environmental protection, and further widen the applications of EMs. This review article aims to present the recent processes in the synthesis and physical and explosive performances of the nitrated-pyrazole-based Ems, including monopyrazoles with nitro, bispyrazoles with nitro, nitropyrazolo[4,3-c]pyrazoles, and their derivatives, and to comb the development trend of these compounds. This review intends to prompt fresh concepts for designing prominent high-performance nitropyrazole-based EMs.


Assuntos
Nitratos/química , Nitrocompostos/química , Pirazóis/química , Substâncias Explosivas/síntese química , Substâncias Explosivas/química , Nitratos/síntese química , Nitrocompostos/síntese química , Pirazóis/síntese química , Termodinâmica
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