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1.
Small ; : e2405950, 2024 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-39224048

RESUMEN

Ultralight graphene aerogels with high electrical conductivity and superelasticity are demanded yet difficult to produce. A versatile emulsion-based approach is demonstrate to optimize multiscale structure of lightweight, elastic, and conductive graphene aerogels. By constructing Pickering emulsion using graphene oxide (GO), poly (amic acid) (PAA), and octadeyl amine (ODA), micron-level close-pore structure is realized while thermal shrinkage mismatch between GO and PAA creates numerous nanowrinkles during thermal annealing. GO nanosheets are bridged by PAA-derived carbon, enhancing the structural integrity at molecular level. These multiscale structural features facilitate rapid electron transport and efficient load transfer, conferring graphene aerogels with intriguing mechanical and electromagnetic interference (EMI) shielding properties. The emulsion-based graphene aerogel with an ultralow density of ≈3.0 mg cm-3 integrates outstanding electrical conductivity, air-caliber thermal insulation, high EMI shielding effectiveness of 75.0 dB, and 90% strain compressibility with superb fatigue resistance. Intriguingly, thanks to the gel-like rheological behavior of the emulsion, ultralight graphene scaffolds with programmable geometries are obtained by 3D printing. This work provides a general approach for the preparation of ultralight and superelastic graphene aerogels with excellent EMI shielding properties, showing broad application prospects in various fields.

2.
Small ; 20(6): e2306104, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-37775948

RESUMEN

Microwave absorbers with high efficiency and mechanical robustness are urgently desired to cope with more complex and harsh application scenarios. However, manipulating the trade-off between microwave absorption performance and mechanical properties is seldom realized in microwave absorbers. Here, a chemistry-tailored charge dynamic engineering strategy is proposed for sparking hetero-interfacial polarization and thus coordinating microwave attenuation ability with the interfacial bonding, endowing polymer-based composites with microwave absorption efficiency and mechanical toughness. The absorber designed by this new conceptual approach exhibits remarkable Ku-band microwave absorption efficiency (-55.3 dB at a thickness of 1.5 mm) and satisfactory effective absorption bandwidth (5.0 GHz) as well as desirable interfacial shear strength (97.5 MPa). The calculated differential charge density depicts the uneven distribution of space charge and the intense hetero-interfacial polarization, clarifying the structure-performance relationship from a theoretical perspective. This work breaks through traditional single performance-oriented design methods and ushers a new direction for next-generation microwave absorbers.

3.
Nano Lett ; 23(1): 155-162, 2023 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-36562701

RESUMEN

The direct 3D printing of ultralight architectures with ultralow-concentration 2D nanomaterial inks is necessary yet challenging. Here, we describe an emulsion-based ink for direct printing using 2D nanomaterials, i.e., MXene and graphene oxide (GO). The electrostatic interactions between the ligands in the oil phase and the 2D nanomaterials in the aqueous phase help form sheet-like surfactants at the interface. The interactions between the anchored ligands among different droplets dictate the rheological characteristics of inks, enabling a gel-like behavior ideally suitable for 3D printing at ultralow concentrations of 2D nanomaterials. The 3D printed foams possess lightweight structures with densities of 2.8 mg cm-3 (GO-based) and 4.1 mg cm-3 (MXene-based), and the latter integrates outstanding electrical conductivity, electromagnetic shielding performance, and thermal insulation comparable to air. This work describes a general approach for direct-printing ultralight porous structures that take advantage of the inherent properties of 2D building blocks.

4.
Small ; 19(46): e2304278, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37431209

RESUMEN

Processing transition metal carbides/nitrides (MXenes) inks into large-area functional coatings expects promising potential for electromagnetic interference (EMI) shielding and infrared stealth. However, the coating performances, especially for scalable fabrication techniques, are greatly constrained by the flake size and stacking manner of MXene. Herein, the large-area production of highly densified and oriented MXene coatings is demonstrated by engineering interfacial interactions of small MXene flakes with catecholamine molecules. The catecholamine molecules can micro-crosslink MXene nanosheets, significantly improving the ink's rheological properties. It favors the shear-induced sheet arrangement and inhibition of structural defects in the blade coating process, making it possible to achieve high orientation and densification of MXene assembly by either large-area coating or patterned printing. Interestingly, the MXene/catecholamine coating exhibits high conductivity of up to 12 247 S cm-1 and ultrahigh specific EMI shielding effectiveness of 2.0 ×10 5  dB cm2 g-1 , obviously superior to most of the reported MXene materials. Furthermore, the regularly assembled structure also endows the MXene coatings with low infrared emissivities for infrared stealth applications. Therefore, MXene/catecholamine coatings with ultraefficient EMI shielding and low infrared emissivity prove the feasibility of applications in aerospace, military, and wearable devices.

5.
Langmuir ; 39(9): 3391-3399, 2023 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-36821086

RESUMEN

Ultrafine explosives show high safety and reliable initiation and have been widely used in aerospace, military, and industrial systems. The outstanding performance of ultrafine explosives is largely given by the unique void defects according to the simulation results. However, the structures and effects of internal nano-voids in ultrafine explosive particles have been rarely investigated experimentally. In this work, contrast-variation small angle X-ray scattering was verified to reliably measure the structures of internal nano-voids in ultrafine explosive 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) and 2,2',4,4',6,6'-hexanitro diphenylethylene (HNS). The size of nano-voids is around 10 nm, and the estimated number of nano-voids in a single particle is considerable. Moreover, the thermal stability of ultrafine LLM-105 was improved via changing the structures of nano-voids. This work provides a methodology for the study of nano-void defects in ultrafine organic particles and may pave the path to enhance the performance of ultrafine explosives via defect engineering.

6.
Int J Mol Sci ; 23(11)2022 May 25.
Artículo en Inglés | MEDLINE | ID: mdl-35682597

RESUMEN

Drought has gradually become one of the most severe abiotic stresses on plants. Plants that experience stress training can exhibit enhanced stress tolerance. According to MicroRNA (miRNA) sequencing data, this study identified 195 candidate drought memory-related miRNAs in wheat, and targets of 64 (32.8%) candidate miRNAs were validated by degradome sequencing. Several drought memory-related miRNAs such as tae-miR9676-5p, tae-MIR9676-p3_1ss21GA, tae-miR171a, tae-miR531_L-2, tae-miR408_L-1, PC-3p-5049_3565, tae-miR396c-5p, tae-miR9778, tae-miR164a-5p, and tae-miR9662a-3p were validated as having a strong response to drought memory by regulating the expression of their target genes. In addition, overexpression of drought memory-related miRNA, tae-miR531_L-2, can remarkably improve the drought tolerance of transgenic Arabidopsisthaliana. Drought memory can regulate plant cellular signal transduction, plant biosynthetic processes, and other biological processes to cope with drought via transcriptional memory. In addition, drought memory-related miRNAs can promote starch and sucrose catabolism and soluble sugar accumulation and regulate proline homeostasis to improve plant drought resistance. Our results could contribute to an understanding of drought memory in wheat seedlings and may provide a new strategy for drought-resistant breeding.


Asunto(s)
MicroARNs , Triticum , Sequías , Regulación de la Expresión Génica de las Plantas , MicroARNs/genética , MicroARNs/metabolismo , Fitomejoramiento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estrés Fisiológico/genética , Triticum/metabolismo
7.
Int J Mol Sci ; 23(2)2022 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-35055085

RESUMEN

Autophagy is an indispensable biological process and plays crucial roles in plant growth and plant responses to both biotic and abiotic stresses. This study systematically identified autophagy-related proteins (ATGs) in wheat and its diploid and tetraploid progenitors and investigated their genomic organization, structure characteristics, expression patterns, genetic variation, and regulation network. We identified a total of 77, 51, 29, and 30 ATGs in wheat, wild emmer, T. urartu and A. tauschii, respectively, and grouped them into 19 subfamilies. We found that these autophagy-related genes (ATGs) suffered various degrees of selection during the wheat's domestication and breeding processes. The genetic variations in the promoter region of Ta2A_ATG8a were associated with differences in seed size, which might be artificially selected for during the domestication process of tetraploid wheat. Overexpression of TaVAMP727 improved the cold, drought, and salt stresses resistance of the transgenic Arabidopsis and wheat. It also promoted wheat heading by regulating the expression of most ATGs. Our findings demonstrate how ATGs regulate wheat plant development and improve abiotic stress resistance. The results presented here provide the basis for wheat breeding programs for selecting varieties of higher yield which are capable of growing in colder, drier, and saltier areas.


Asunto(s)
Proteínas Relacionadas con la Autofagia/genética , Autofagia/genética , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Triticum/fisiología , Proteínas Relacionadas con la Autofagia/metabolismo , Biomarcadores , Biología Computacional/métodos , Diploidia , Perfilación de la Expresión Génica , Fenotipo , Filogenia , Polimorfismo de Nucleótido Simple , Mapeo de Interacción de Proteínas , Estrés Fisiológico , Tetraploidía
8.
Molecules ; 27(12)2022 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-35744992

RESUMEN

Nano-scale crystal defects extremely affect the security and reliability of explosive charges of weapons. In this work, the nano-scale crystal defects of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) single crystals were characterized by two-dimension SAXS. Deducing from the changes of SAXS pattern with sample stage rotating, we firstly found the parallel lamellar nano-scale defects in both RDX and HMX single crystals. Further analysis shows that the average diameter and thickness of nano-scale lamellar defects for RDX single crystal are 66.4 nm and 19.3 nm, respectively. The results of X-ray diffraction (XRD) indicate that the lamellar nano-scale defects distribute along the (001) in RDX and the (011) in HMX, which are verified to be the crystal planes with the lowest binding energy by the theoretical calculation.

9.
Phys Chem Chem Phys ; 23(21): 12340-12349, 2021 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-34019605

RESUMEN

Plate-like ß-HMX crystals are grown in the hydroxylated interlayer space using a crystallization technique combining the cooling crystallization and solvent-antisolvent methods. The obtained crystals have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The experimental results indicate that the most morphologically important face of the plate-like ß-HMX crystals is the (011) face adopting a layer-by-layer growth mode. Meanwhile, molecular dynamics (MD) simulations were performed to study the crystal morphology in HMX crystal growth in the hydroxylated interlayer space based on a modified attachment energy (MAE) model. The calculated results show that the major face is the (011) face and the interaction energies between the crystal face and the hydroxylated interlayer are in the order of (011) > (110) > (020), which agree well with the experimental results above.

10.
Molecules ; 25(3)2020 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-31973082

RESUMEN

Small-angle X-ray scattering (SAXS) is an effective method to obtain microstructural information of materials. However, due to the influence of crystal surface effects, SAXS has a deviation in the characterization of the crystal microstructure. In order to solve the influence of crystal surface effect on the internal defect signal, the microstructure of Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) crystal was characterized by soaking the sample in the matching solution. We found that the absolute scattering intensity, specific surface and volume fraction of the sample in the matching solution are significantly lower than the initial sample, which solves the influence of the crystal surface effect on the test results. Comparing the scattering results of the samples in different electron density matching solutions, it was found that the best result was obtained when using GPL-107 perfluoropolyether (PFPE) matching solution and the same law was obtained by controlling the experiment with 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20) crystal. The fitting density was calculated according to the theoretical density and void volume fraction of the sample, and the calculated results are close to the test results of Particle Density Distribution Analyzer (PDDA). Based on this paper, we provide a method to obtain the correct information of crystal microstructure.


Asunto(s)
Azocinas/química , Dispersión del Ángulo Pequeño , Difracción de Rayos X , Cristalización , Tamaño de la Partícula , Soluciones , Electricidad Estática
11.
Angew Chem Int Ed Engl ; 58(50): 18171-18176, 2019 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-31591756

RESUMEN

2D transition metal carbides and nitrides (MXenes), a class of emerging nanomaterials with intriguing properties, have attracted significant attention in recent years. However, owing to the highly hydrophilic nature of MXene nanosheets, assembly strategies of MXene at liquid-liquid interfaces have been very limited and challenging. Herein, through the cooperative assembly of MXene and amine-functionalized polyhedral oligomeric silsesquioxane at the oil-water interface, we report the formation, assembly, and jamming of a new type MXene-based Janus-like nanoparticle surfactants, termed MXene-surfactants (MXSs), which can significantly enhance the interfacial activity of MXene nanosheets. More importantly, this simple assembly strategy opens a new platform for the fabrication of functional MXene assemblies from mesoscale (e.g., structured liquids) to macroscale (e.g., aerogels), that can be used for a range of applications, including nanocomposites, electronic devices, and all-liquid microfluidic devices.

12.
Small ; 14(45): e1802479, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30295015

RESUMEN

2D transition metal carbides and nitrides (MXenes) have gained extensive attention recently due to their versatile surface chemistry, layered structure, and intriguing properties. The assembly of MXene sheets into macroscopic architectures is an important approach to harness their extraordinary properties. However, it is difficult to construct a freestanding, mechanically flexible, and 3D framework of MXene sheets owing to their weak intersheet interactions. Herein, an interfacial enhancement strategy to construct multifunctional, superelastic, and lightweight 3D MXene architectures by bridging individual MXene sheets with polyimide macromolecules is developed. The resulting lightweight aerogel exhibits superelasticity with large reversible compressibility, excellent fatigue resistance (1000 cycles at 50% strain), 20% reversible stretchability, and high electrical conductivity of ≈4.0 S m-1 . The outstanding mechanical flexibility and electrical conductivity make the aerogel promising for damping, microwave absorption coating, and flexible strain sensor. More interestingly, an exceptional microwave absorption performance with a maximum reflection loss of -45.4 dB at 9.59 GHz and a wide effective absorption bandwidth of 5.1 GHz are achieved.

13.
J Orthop Surg (Hong Kong) ; 32(2): 10225536241277604, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39155598

RESUMEN

OBJECTIVES: Platelet-rich plasma treatment delays the need for total knee replacement in patients with knee osteoarthritis. However, its use and preparation remain controversial. The aim of this study was to investigate the relationship between anticoagulant use in the preparation of platelet-rich plasma and post-treatment pain in patients with knee osteoarthritis. Additionally, we explored the efficacy of platelet-rich plasma over medium- and long-term follow-up periods and identified other factors that may affect treatment outcomes. METHODS: In this retrospective study, 225 patients with knee osteoarthritis, who underwent knee platelet-rich plasma treatment from June 2021 to January 2022, were examined at three study centres. Patients were categorised, based on the type and amount of anticoagulant used during platelet-rich plasma preparation, into 4% sodium citrate (SC) 0.6 mL, 4% SC 1 mL, 4% SC 2 mL, heparin 0.1 mL, and heparin 0.2 mL groups. We analysed the patients' basic information, pain after treatment, and inflammatory markers (i.e., interleukin 6, tumour necrosis factor-α, and hypersensitive C-reactive protein) in the joint fluid via enzyme-linked immunosorbent assay and joint fluid crystallisation. Additionally, we assessed the patients' Western Ontario and McMaster University scores and minimal clinically significant differences after treatment. RESULTS: Patients in the 4% SC 0.6 mL and heparin 0.1 mL groups experienced less pain after platelet-rich plasma treatment than did patients in the high-dose anticoagulant group. The joint fluid of patients with pain in these groups had lower levels of inflammatory markers. Patients treated with SC had slightly better medium- and long-term therapeutic outcomes than did patients treated with heparin. Patients with poorly controlled hyperuricemia also experienced pain after platelet-rich plasma treatment. CONCLUSIONS: The results suggest that platelet-rich plasma prepared using high-dose anticoagulants or administered to patients with poorly controlled hyperuricaemia may lead to moderate-to-severe knee pain and joint effusion after joint puncture therapy. Platelet-rich plasma had a therapeutic effect on knee osteoarthritis; however, its efficacy gradually decreased over time. SC anticoagulant is more suitable for platelet-rich plasma preparation than is heparin. Further studies are needed to understand the safety and the various factors influencing platelet-rich plasma therapy.


Asunto(s)
Anticoagulantes , Hiperuricemia , Osteoartritis de la Rodilla , Plasma Rico en Plaquetas , Humanos , Estudios Retrospectivos , Masculino , Femenino , Osteoartritis de la Rodilla/terapia , Anticoagulantes/administración & dosificación , Anciano , Hiperuricemia/terapia , Hiperuricemia/complicaciones , Persona de Mediana Edad , Artralgia/etiología , Artralgia/terapia , Artralgia/diagnóstico , Heparina/administración & dosificación , Citrato de Sodio/administración & dosificación , Inyecciones Intraarticulares , Dimensión del Dolor
14.
Zhen Ci Yan Jiu ; 49(3): 247-255, 2024 Mar 25.
Artículo en Inglés, Zh | MEDLINE | ID: mdl-38500321

RESUMEN

OBJECTIVES: To observe the effect of Guasha on inflammation factors, apoptosis and autophagy in the cartilage tissue of knee joint in rats with knee osteoarthritis (KOA), so as to explore its mechanisms underlying improvement of KOA. METHODS: A total of 51 male SD rats were randomized into three groups:blank control, KOA model and Guasha (n= 17 in each group) . The rats in the blank control group received intra-articular injection of 0.9% NaCl solution in the right knee joint. The KOA model was established by intraarticular injection of glutamate sodium iodoacetic acid in the right knee joint. For rats of the Guasha group, Guasha (at a frequency of 1 time/s, and an applied pressure of 0.3-0.5 kgf) was applied to "Yanglingquan" (GB34) and "Xuehai"(SP10) areas of the right leg, once every other day, for 7 consecutive sessions. The circumference of the right knee was measured, The histopathological changes of right knee cartilage were observed after H.E. staining. The contents of inflammatory factors interleukin (IL)-1ß and tumor necrosis factor (TNF)-α in the right knee articular cartilage tissue were assayed using ELISA. The expression levels of autophagy-related key molecule Beclin-1 (homologous series of yeast Atg6), light chain protease complication 3 type II/I (LC3II/LC3 I), ubiquitin binding factor 62 (P62) and cysteine aspartate protease-3 (Caspase-3) mRNAs and proteins of the right knee articular cartilage tissue were measured using real-time fluorescent quantitative PCR and Western blot, separately. The apoptosis of chondrocytes was assayed using TUNEL staining, and the immunoactivity of LC3 determined using immunofluorescence staining. RESULTS: After modeling, the right knee circumfe-rence of the model and Guasha groups was significantly increased compared with the blank control group (P<0.01), and after the intervention, the knee circumference of the Guasha group was markedly decreased in comparison with that of the model group (P<0.05). Results of H.E. staining showed obvious degeneration and defects in the cartilage tissue, necrosis of a large number of chondrocytes, fibrous hyperplasia, accompanied by inflammatory cell infiltration, osteoclast increase, fibroplasia and bone trabecular destruction in the model group, which was relatively milder in the Guasha group. Compared with the blank control group, the expression of Beclin-1 and LC3 mRNAs and proteins, and LC immunofluorescence intensity in the right knee articular cartilage tissue were significantly down-regulated (P<0.01, P<0.001), whereas the expression of P62 and Caspase-3 mRNAs and proteins, the apoptosis rate, contents of IL-1ß and TNF-α in the right knee articular cartilage tissue considerably increased (P<0.01, P<0.001) in the model group. In contrast to the model group, the Guasha group had an apparent increase in the expression levels of Beclin-1 and LC3 mRNAs and proteins and LC immunofluorescence intensity in the right knee articular cartilage tissue (P<0.05), and a pronounced decrease in the expression of P62 and Caspase-3 mRNAs and proteins, the apoptosis rate, and contents of IL-1ß and TNF-α in the right knee articular cartilage tissue (P<0.05, P<0.01). CONCLUSIONS: Guasha stimulation of GB34 and SP10 can improve joint cartilage damage in KOA rats, which may be associated with its functions in inhibiting the excessive release of inflammatory factors and apoptosis, possibly by down-regulating the expression of P62 and Caspase-3 mRNAs and proteins and up-regulating the expression of Beclin-1 and LC3 mRNAs and proteins, and by promoting autophagy of chondrocytes.


Asunto(s)
Osteoartritis de la Rodilla , Ratas , Masculino , Animales , Osteoartritis de la Rodilla/genética , Osteoartritis de la Rodilla/terapia , Caspasa 3/metabolismo , Condrocitos/metabolismo , Ratas Sprague-Dawley , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismo , Beclina-1/metabolismo , Apoptosis/genética , Autofagia/genética
15.
Adv Mater ; 36(14): e2310849, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38185468

RESUMEN

Flexible and adaptable polymer composites with high-performance reliability over wide temperature range are imperative for various applications. However, the distinct filler-matrix thermomechanical behaviors often cause severe structure damage and performance degradation upon large thermal shock. To address this issue, a general strategy is proposed to construct leakage-free, self-adaptive, stable percolation networks in polymer composites over wide temperature (77-473 K) with biphasic Ga35In65 alloy. The in situ micro-CT technology, for the first time, reveals the conformable phase transitions of Ga35In65 alloys in the polymer matrix that help repair the disruptive conductive networks over large temperature variations. The cryo-expanded Ga compensates the disruptive carbon networks at low temperatures, and flowable Ga and melted In at high temperatures conformably fill and repair the deboned interfaces and yielded crevices. As a proof-of-concept, this temperature-resistant composite demonstrates superb electrical conductivity and electromagnetic interference shielding properties and stability even after a large temperature shock (ΔT = 396 K). Furthermore, the superiority of the construction of temperature self-adaptive networks within the composite enables them for additive manufacturing of application-oriented components. This work offers helpful inspiration for developing high-performance polymer composites for extreme-temperature applications.

16.
ACS Appl Mater Interfaces ; 16(10): 13082-13090, 2024 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-38416690

RESUMEN

Smart electromagnetic interference (EMI) shielding materials are of great significance in coping with the dynamic performance demands of cutting-edge electronic devices. However, smart EMI shielding materials are still in their infancy and face a variety of challenges (e.g., large thickness, limited tunable range, poor reversibility, and unclear mechanisms). Here, we report a method for controllable shielding electromagnetic (EM) waves through subwavelength structure changes regulated by the customized structure via a direct printing route. The highly conductive MXene ink is regulated with metal ions (Al3+ ions), giving superb metallic conductivity (∼5000 S cm-1) for the printed lines without an annealing treatment. The reversible tunability of EMI shielding effectiveness (SE) ranging from 8.2 dB ("off" state) to 34 dB ("on" state) is realized through the controllable modulation of subwavelength structure driven by stress. This work provides a feasible strategy to develop intelligent shielding materials and EM devices.

17.
ACS Appl Mater Interfaces ; 15(3): 4591-4600, 2023 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-36634284

RESUMEN

Solution processing of two-dimensional nanomaterial inks guarantees efficient, straightforward fabrication of functional films, coatings, flexible devices, etc. Despite the excellent solution processibility and viscoelasticity of MXene aqueous inks, formulation of nonaqueous MXene inks with great affinity to both hydrophilic and hydrophobic substrates has proven quite challenging, limiting the practical applications of MXenes in printing/coatings on various substrates. Here, MXene surface chemistry is manipulated by asymmetrically grafting polystyrene and further concentrating the flakes into additive-free Janus MXene organic inks. The modified MXene nanosheets exhibit hydrophilicity on one side and hydrophobicity on the other. As a result, Janus MXene nanosheets ensure broad dispersibility in polar and nonpolar solvents, which in turn greatly extends the ink shelf life by slowing down the oxidation kinetics. Janus MXene sheets dispersed in toluene at room temperature remain at 90% of the initial solids after 1 month of storage. Janus surface engineering on MXene flakes guarantees the straightforward formation of uniform yet firm, large-area coatings on hydrophilic or hydrophobic substrates. These coatings demonstrate improved photothermal properties and chemical stability as well as good electromagnetic interference shielding performance. This strategy provides a simple and cost-effective way to promote the performance of MXene electronics in a variety of applications.

18.
Zhen Ci Yan Jiu ; 48(4): 359-65, 2023 Apr 25.
Artículo en Zh | MEDLINE | ID: mdl-37186200

RESUMEN

OBJECTIVE: To compare the effects of moxibustion and scraping of "Yanglingquan" (GB34) and "Xuehai" (SP10) area on changes of bioactive substances in the region of acupoints in rats with knee osteoarthritis (KOA). METHODS: SD rats were randomly divided into blank, model, moxibustion, scraping, and moxibustion + scraping (combination) groups, with 8 rats in each group. The KOA model was established by injecting 50 µL 0.9% sodium chloride solution into the right knee cavity. Fourteen days after modeling, GB34 and SP10 on the right limb were stimulated by moxibustion (10 min) or scraping (till regional flush) once every other day for 7 times. The mechanical paw withdrawal threshold (PWT) and thermal withdrawal latency (TWL) were tested by Von Frey and hot stabbing instrument, separately. The pathological changes of the right knee joint were observed by HE staining. The serotonin (5-HT) contents of skin tissues in the region of acupoint GB34 and SP10 were detected by ELISA. The expression levels of substance P (SP) and calcitonin gene-related peptide (CGRP) in GB34 and SP10 region skin tissues were detected by Western blot. RESULTS: Compared with the blank group, the PWT and TWL of the rats in the model group were significantly decreased (P<0.001), while the contents of 5-HT and the expression levels of SP and CGRP in GB34 and SP10 region skin tissues were significantly increased (P<0.001, P<0.01). Following intervention and in comparison the with the model group, the TWL and PWT of rats in the three treatment groups were significantly increased (P<0.01), the content of 5-HT and the expression levels of SP and CGRP in GB34 and SP10 region skin tissues were significantly decreased (P<0.01, P<0.001, P<0.05). Except for the expression levels of CGRP, the above indexes of the combination group were significantly superior to those of the moxibustion and scraping groups (P<0.05, P<0.01). Findings of HE staining showed severe damaged cartilage, few chondrocytes on the surface, with subchondral neovascularization in the model group, which was relatively milder in the moxibustion, scraping, and combination groups. CONCLUSION: Moxibustion and scraping can relieve knee joint pain in KOA rats, which may be associated with its function in down-regulating the expression levels of SP and CGRP, and the content of 5-HT. The therapeutic effect of moxibustion plus scraping is better than that of moxibustion and scraping alone.


Asunto(s)
Moxibustión , Osteoartritis de la Rodilla , Ratas , Animales , Osteoartritis de la Rodilla/genética , Osteoartritis de la Rodilla/terapia , Puntos de Acupuntura , Ratas Sprague-Dawley , Péptido Relacionado con Gen de Calcitonina/genética , Serotonina , Sustancia P/genética
19.
Materials (Basel) ; 15(12)2022 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-35744317

RESUMEN

Nano-scale crystal defects extremely affect the security and reliability of the explosive charges of weapons. In order to understand the evolution of nano-scale defects of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane (CL-20) explosive crystals under thermal treatments, the specific surface, volume fraction and size distribution of the nano-scale defects were studied by using Wide Angle X-ray Scattering (WAXS) and Small Angle X-ray Scattering (SAXS) during the temperature range from 30 °C to 200 °C. The results showed that the number and size of the pores in CL-20 powder did not change significantly during the heating process before phase transformation (30-160 °C). At 170 °C, CL-20 began to convert from ε- to γ- phase, and the specific surface and volume fraction of the nano-scale defects increased significantly. Further investigation of the pore size distribution showed that the number of pores with a small size (radius 9-21 nm) changed particularly significantly, resulting from the cracking of the CL-20 crystal powder during phase transition. At 200 °C, the phase transition was completed and γ-CL-20 was created, and the small-sized pores gradually grew into medium-sized (radius 21-52 nm) pores over time when the temperature was fixed at 200 °C.

20.
ACS Nano ; 16(6): 8869-8880, 2022 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-35604787

RESUMEN

Mechanical-electrical properties of macroscopic graphene films derived from graphene oxide (GO) sheets are substantially restricted by their surface wrinkles and structural misalignment. Herein, we propose a chemical-structure-engineering strategy to realize the spontaneously regular stacking of modified GO (GO-m) with trace carboxyl. The highly aligned GO-m film delivers a fracture strength and modulus of nearly 3- and 5-fold higher than a wrinkled film with conventional Hummer's method derived GO (GO-c). The favorable assembly pattern of GO-m sheets is attributed to their decreased interfacial friction on the atomic scale, which weakens their local gelation capability for freer configuration adjustment during the assembly process. The chemical structure of GO-m can be further engineered by an epoxide-to-hydroxyl reaction, achieving a record high tensile strength of up to 631 MPa for the pristine GO film. By exploring the relationship between the surface terminations of GO and its stacking mode, this work proves the feasibility to realize high-performance macroscopic materials with optimized microstructure through the chemical modulation of nanosheet assembly.

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