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1.
Sci Total Environ ; 942: 173697, 2024 Jun 06.
Article in English | MEDLINE | ID: mdl-38851350

ABSTRACT

Surfactants as synergistic agents are necessary to improve the stability and utilization of pesticides, while their use is often accompanied by unexpected release into the environment. However, there are no efficient strategies available for screening low-toxicity surfactants, and traditional toxicity studies rely on extensive experimentation which are not predictive. Herein, a commonly used agricultural adjuvant Triton X (TX) series was selected to study the function of amphipathic structure to their toxicity in zebrafish. Molecular dynamics (MD) simulations, transcriptomics, metabolomics and machine learning (ML) were used to study the toxic effects and predict the toxicity of various TX. The results showed that TX with a relatively short hydrophilic chain was highly toxic to zebrafish with LC50 of 1.526 mg/L. However, TX with a longer hydrophilic chain was more likely to damage the heart, liver and gonads of zebrafish through the arachidonic acid metabolic network, suggesting that the effect of surfactants on membrane permeability is the key to determine toxic results. Moreover, biomarkers were screened through machine learning, and other hydrophilic chain lengths were predicted to affect zebrafish heart health potentially. Our study provides an advanced adjuvants screening method to improve the bioavailability of pesticides while reducing environmental impacts.

2.
Nat Commun ; 15(1): 4472, 2024 May 25.
Article in English | MEDLINE | ID: mdl-38796498

ABSTRACT

Skyrmions in existing 2D van der Waals (vdW) materials have primarily been limited to cryogenic temperatures, and the underlying physical mechanism of the Dzyaloshinskii-Moriya interaction (DMI), a crucial ingredient for stabilizing chiral skyrmions, remains inadequately explored. Here, we report the observation of Néel-type skyrmions in a vdW ferromagnet Fe3-xGaTe2 above room temperature. Contrary to previous assumptions of centrosymmetry in Fe3-xGaTe2, the atomic-resolution scanning transmission electron microscopy reveals that the off-centered FeΙΙ atoms break the spatial inversion symmetry, rendering it a polar metal. First-principles calculations further elucidate that the DMI primarily stems from the Te sublayers through the Fert-Lévy mechanism. Remarkably, the chiral skyrmion lattice in Fe3-xGaTe2 can persist up to 330 K at zero magnetic field, demonstrating superior thermal stability compared to other known skyrmion vdW magnets. This work provides valuable insights into skyrmionics and presents promising prospects for 2D material-based skyrmion devices operating beyond room temperature.

3.
Int J Biol Macromol ; 271(Pt 1): 132514, 2024 May 18.
Article in English | MEDLINE | ID: mdl-38768917

ABSTRACT

Accurate early diagnosis of rheumatoid arthritis (RA) and prompt implementation of appropriate treatment approaches are crucial. In the clinic, magnetic resonance imaging (MRI) has been recommended for implementation to aid in the precise and early diagnosis of RA. However, they are still limited by issues regarding specificity and their ability to capture comprehensive information about the pathological features. Herein, a responsive multifunctional nanoplatform with targeting capabilities (hMnO2-IR@BSA-PEG-FA) is constructed through integrating a RA microenvironment-responsive MRI contrast agent with activatable near-infrared (NIR) fluorescence imaging, aiming to simultaneously acquire comprehensive pathological features of RA from both structural and molecular imaging perspectives. Moreover, taking advantage of its targeting function to synovial microphages, hMnO2-IR@BSA-PEG-FA demonstrated a remarkable capability to accumulate effectively at the synovial tissue. Additionally, hMnO2 responded to the mild acidity and reactive oxygen species (ROS) in the RA microenvironment, leading to the controlled release of Mn2+ ions and IR780, which separately caused special MRI contrast enhancement of synovial tissues and sensitively demonstrated the presence of ROS and weakly acid microenvironment by NIR imaging. Consequently, hMnO2-IR@BSA-PEG-FA is expected to serve as a promising nanoplatform, offering valuable assistance in the precise diagnosis of early-stage RA by specially providing comprehensive information about the pathological features.

4.
Polymers (Basel) ; 16(7)2024 Apr 05.
Article in English | MEDLINE | ID: mdl-38611256

ABSTRACT

With the development of the shipbuilding industry, it is necessary to improve tribological properties of polyether ether ketone (PEEK) as a water-lubricated bearing material. In this study, the sulfonated PEEK (SPEEK) with three distinct chemical structures was synthesized through direct sulfonated polymerization, and high fault tolerance and a controllable sulfonation degree ensured the batch stability. The tribological and mechanical properties of SPEEK with varying side groups (methyl and tert-butyl) and rigid segments (biphenyl) were compared after sintering in a vacuum furnace. Compared to the as-made PEEK, as the highly electronegative sulfonic acid group enhanced the hydration lubrication, the friction coefficient and wear rate of SPEEK were significantly reduced by 30% and 50% at least without affecting the mechanical properties. And lower steric hindrance and entanglement between molecular chains were proposed to be partially responsible for the lowest friction behavior of SPEEK with methyl side groups, making it a promising and competitive option for water-lubricated bearings.

6.
Nat Commun ; 15(1): 2234, 2024 Mar 12.
Article in English | MEDLINE | ID: mdl-38472180

ABSTRACT

Coherent spin waves possess immense potential in wave-based information computation, storage, and transmission with high fidelity and ultra-low energy consumption. However, despite their seminal importance for magnonic devices, there is a paucity of both structural prototypes and theoretical frameworks that regulate the spin current transmission and magnon hybridization mediated by coherent spin waves. Here, we demonstrate reconfigurable coherent spin current transmission, as well as magnon-magnon coupling, in a hybrid ferrimagnetic heterostructure comprising epitaxial Gd3Fe5O12 and Y3Fe5O12 insulators. By adjusting the compensated moment in Gd3Fe5O12, magnon-magnon coupling was achieved and engineered with pronounced anticrossings between two Kittel modes, accompanied by divergent dissipative coupling approaching the magnetic compensation temperature of Gd3Fe5O12 (TM,GdIG), which were modeled by coherent spin pumping. Remarkably, we further identified, both experimentally and theoretically, a drastic variation in the coherent spin wave-mediated spin current across TM,GdIG, which manifested as a strong dependence on the relative alignment of magnetic moments. Our findings provide significant fundamental insight into the reconfiguration of coherent spin waves and offer a new route towards constructing artificial magnonic architectures.

7.
J Inflamm Res ; 17: 1389-1396, 2024.
Article in English | MEDLINE | ID: mdl-38476469

ABSTRACT

Background: An unmet medical need for the treatment of inflammatory bowel disease (IBD) exists. A part of antidiabetic drugs had potential effects on IBD in various observational research. Objective: To investigate the potential of antidiabetic drugs on IBD. Methods: We undertook a summary-data-based Mendelian randomization (SMR) using the expression quantitative trait loci (eQTL) expressed in the blood or colon and a two sample Mendelian randomization (TSMR) utilizing single nucleotide polymorphism (SNP) of antidiabetic drug target genes mediated by blood glucose traits. Participants encompassed patients with IBD (25,042 cases/34,915 controls), UC (12,366 cases/33,609 controls), and CD (12,194 cases/28,072 controls). Data on eQTL in the blood or the colon were from the eQTLGen consortium (31,684 individuals) or GTEx Consortium V8, respectively. SMR was performed by SMR software (20,220,322); the primary method for TSMR was inverse-variance weighted (IVW) or Wald ratio through R studio (2023.06.0+421). Sensitivity analyses were carried out. Results: A 1-SD upper expression of the KCNJ11 gene (target gene of sulfonylureas) in the blood reduced the risk of CD (OR per 1-SD = 0.728, 95% CI = 0.586-0.903, P = 0.004) according to the result of SMR. ABCC8 (target gene of sulfonylureas) expressed in the colon did not affect CD, UC, or IBD. T2D-mediated KCNJ11 has a protective effect on CD (OR = 0.475, 95% CI = 0.297-0.761, P = 0.002). Gene predicted no relationship between T2D and CD. Conclusion: Sulfonylureas (SUs) may have side effects on CD. This work provides some suggestions for the selection of antidiabetic drugs in patients with CD.

8.
ACS Nano ; 18(13): 9486-9499, 2024 Apr 02.
Article in English | MEDLINE | ID: mdl-38497998

ABSTRACT

Agrichemical losses are a severe threat to the ecological environment. Additionally, some agrichemical compounds contain abundant salt, which increases the instability of formulations, leading to a lower agrichemical utilization and soil hardening. Fortunately, the biological amphiphilic emulsifier sodium deoxycholate alleviates these problems by forming stable Janus core-shell emulsions through salinity-driven interfacial self-assembly. According to the interfacial behavior, dilational rheology, and molecular dynamics simulations, Janus-emulsion molecules are more closely arranged than traditional-emulsion molecules and generate an oil-water interfacial film that transforms into a gel film. In addition, at the same spray volume, the deposition area of the Janus emulsion increased by 37.70% compared with that of the traditional emulsion. Owing to the topology effect and deformation, the Janus emulsion adheres to rice micropapillae, achieving better flush resistance. Meanwhile, based on response of the Janus emulsion to stimulation by carbon dioxide (CO2), the emulsion lost to the soil can form a rigid shell for inhibiting the release of pesticides and metal ions from harming the soil. The pyraclostrobin release rate decreased by 50.89% at 4 h after the Janus emulsion was exposed to CO2. The Chao1 index of the Janus emulsion was increased by 12.49% as compared to coconut oil delivery in soil microbial community. The Janus emulsion ingested by harmful organisms can be effectively absorbed in the intestine to achieve better control effects. This study provides a simple and effective strategy, which turns waste into treasure, by combining metal ions in agrichemicals with natural amphiphilic molecules to prepare stable emulsions for enhancing agrichemical rainfastness and weakening environmental risk.


Subject(s)
Agrochemicals , Salinity , Emulsions/chemistry , Carbon Dioxide , Ions , Soil
9.
Inflamm Bowel Dis ; 2024 Feb 26.
Article in English | MEDLINE | ID: mdl-38408068

ABSTRACT

BACKGROUND: Periodontitis has been reported to be associated with inflammatory bowel disease (IBD), including ulcerative colitis (UC), and Crohn's disease (CD). However, the causality of these 2 diseases remains unclear. We conducted bidirectional Mendelian randomization (MR) to investigate the causal relationship between periodontitis and IBD. METHODS: We obtained the genome-wide association study (GWAS) summary data of European populations from FinnGen database (for IBD) and a published article (for periodontitis), from which independent single nucleotide polymorphisms were selected as instrumental variables. Inverse variance-weighted (IVW), MR-Egger, and weighted median (WM) methods were utilized for MR analysis. Heterogeneity or pleiotropy was detected through Cochran's Q test and MR-Egger intercept, respectively. Outlier was identified with MR-PRESSO (Mendelian Randomization Pleiotropy RESidual Sum and Outlier) and leave-one-out analysis. All statistical analyses were performed with R 4.2.1 and the packages of TwoSampleMR version 0.5.6. RESULTS: Genetic prediction showed that periodontitis was the risk factor of UC (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.01-1.26; P = .027), rather than of CD (OR, 0.92; 95% CI, 0.74-1.15; P = .456) and IBD (OR, 0.96; 95% CI, 0.81-1.13; P = .619). To the contrary, CD, not UC or IBD, resulted in exacerbating periodontitis in terms of the results of the IVW (OR, 1.09; 95% CI, 1.01-1.17; P = .021) and WM (OR, 1.10; 95% CI, 1.01-1.20; P = .030) methods. Heterogeneity or pleiotropy was acceptable. CONCLUSIONS: Our results indicated that CD was the risk factor for periodontitis; conversely, periodontitis was responsible for the exacerbation of UC, enhancing the existence of mouth-gut axis. Patients with UC should pay more attention to periodontal health, while patients with periodontitis should actively pay close heed to intestinal health.


A bidirectional Mendelian randomization study indicated that Crohn's disease was the risk factor for periodontitis; conversely, periodontitis was responsible for the exacerbation of ulcerative colitis, enhancing the existence of the mouth-gut axis and suggesting paying attention to oral health for patients of inflammatory bowel disease.

10.
Neuroradiology ; 66(3): 443-455, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38183426

ABSTRACT

BACKGROUND: Optimal lumbar puncture segment selection remains controversial. This study aims to analyze anatomical differences among L3-4, L4-5, and L5-S1 segments across age groups and provide quantitative evidence for optimized selection. METHODS: 80 cases of CT images were collected with patients aged 10-80 years old. Threedimensional models containing L3-S1 vertebrae, dural sac, and nerve roots were reconstructed. Computer simulation determined the optimal puncture angles for the L3-4, L4-5, and L5-S1 segments. The effective dural sac area (ALDS), traversing nerve root area (ATNR), and area of the lumbar inter-laminar space (ALILS) were measured. Puncture efficacy ratio (ALDS/ALILS) and nerve injury risk ratio (ATNR/ALILS) were calculated. Cases were divided into four groups: A (10-20 years), B (21-40 years), C (41-60 years), and D (61-80 years). Statistical analysis was performed using SPSS. RESULTS: 1) ALDS was similar among segments; 2) ATNR was greatest at L5-S1; 3) ALILS was greatest at L5-S1; 4) Puncture efficacy ratio was highest at L3-4 and lowest at L5-S1; 5) Nerve injury risk was highest at L5-S1. In group D, L5-S1 ALDS was larger than L3-4 and L4-5. ALDS decreased after age 40. Age variations were minimal across parameters. CONCLUSION: The comprehensive analysis demonstrated L3-4 as the optimal first-choice segment for ages 10-60 years, conferring maximal efficacy and safety. L5-S1 can serve as an alternative option for ages 61-80 years when upper interspaces narrow. This study provides quantitative imaging evidence supporting age-specific, optimized lumbar puncture segment selection.


Subject(s)
Lumbar Vertebrae , Spinal Puncture , Humans , Child , Adolescent , Young Adult , Adult , Middle Aged , Aged , Aged, 80 and over , Computer Simulation , Lumbar Vertebrae/diagnostic imaging , Lumbosacral Region , Tomography, X-Ray Computed
11.
ACS Nano ; 18(1): 761-769, 2024 Jan 09.
Article in English | MEDLINE | ID: mdl-38127497

ABSTRACT

Magnetic skyrmions are topologically protected swirling spin textures with great potential for future spintronic applications. The ability to induce skyrmion motion using mechanical strain not only stimulates the exploration of exotic physics but also affords the opportunity to develop energy-efficient spintronic devices. However, the experimental realization of strain-driven skyrmion motion remains a formidable challenge. Herein, we demonstrate that the inhomogeneous uniaxial compressive strain can induce the movement of isolated skyrmions from regions of high strain to regions of low strain at room temperature, which was directly observed using an in situ Lorentz transmission electron microscope with a specially designed nanoindentation holder. We discover that the uniaxial compressive strain can transform skyrmions into a single domain with in-plane magnetization, resulting in the coexistence of skyrmions with a single domain along the direction of the strain gradient. Through comprehensive micromagnetic simulations, we reveal that the repulsive interactions between skyrmions and the single domain serve as the driving force behind the skyrmion motion. The precise control of skyrmion motion through strain provides exciting opportunities for designing advanced spintronic devices that leverage the intricate interplay between strain and magnetism.

12.
Langmuir ; 40(1): 805-817, 2024 Jan 09.
Article in English | MEDLINE | ID: mdl-38134349

ABSTRACT

In this article, five kinds of 1,3-diketones and their chelates with different molecular structures were prepared, and their tribological properties were tested. The experimental results show that the running-in time and friction coefficient of the friction pairs lubricated by 1,3-diketones containing a benzene ring increased with the increase of the carbon chain length. In addition, only the friction pair lubricated by 1-(4-ethylphenyl)-butane-1,3-dione (0201) and 1-(4-ethylphenyl)-nonane-1,3-dione (0206) could achieve stable superlubricity. When the benzene ring was replaced with a carbon six-membered ring, it was found that although the friction pair lubricated by this lubricant could achieve superlubricity, the wear of the friction pair was severe, and obvious abrasive wear occurred. In addition, the lubricants prepared by mixing 1,3-diketones and the corresponding chelates in a ratio of 4:6 had greatly improved lubricating properties compared to 1,3-diketones. Through X-ray photoelectron spectroscopy (XPS) analysis of the surface of the friction pair after the test and Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) analyses of 1,3-diketones before and after the experiment, we found that the necessary conditions for the friction pair lubricated by 1,3-diketone to achieve superlubricity were formation of tribochemical adsorption films and the presence of chelates in solution.

13.
Nat Commun ; 14(1): 7891, 2023 Nov 30.
Article in English | MEDLINE | ID: mdl-38036500

ABSTRACT

Layered thio- and seleno-phosphate ferroelectrics, such as CuInP2S6, are promising building blocks for next-generation nonvolatile memory devices. However, because of the low Curie point, the CuInP2S6-based memory devices suffer from poor thermal stability (<42 °C). Here, exploiting the electric field-driven phase transition in the rarely studied antiferroelectric CuCrP2S6 crystals, we develop a nonvolatile memristor showing a sizable resistive-switching ratio of ~ 1000, high switching endurance up to 20,000 cycles, low cycle-to-cycle variation, and robust thermal stability up to 120 °C. The resistive switching is attributed to the ferroelectric polarization-modulated thermal emission accompanied by the Fowler-Nordheim tunneling across the interfaces. First-principles calculations reveal that the good device performances are associated with the exceptionally strong ferroelectric polarization in CuCrP2S6 crystal. Furthermore, the typical biological synaptic learning rules, such as long-term potentiation/depression and spike amplitude/spike time-dependent plasticity, are also demonstrated. The results highlight the great application potential of van der Waals antiferroelectrics in high-performance synaptic devices for neuromorphic computing.

14.
Mediators Inflamm ; 2023: 3706421, 2023.
Article in English | MEDLINE | ID: mdl-37789884

ABSTRACT

Introduction: Osteoarthritis (OA) is the most common degenerative joint disorder. Prior studies revealed that activation of NLRP3 inflammasome could promote the activation and secretion of interleukin-1ß (IL-1ß), which has an adverse effect on the progression of OA. Betulinic acid (BA) is a compound extract of birch, whether it can protect against OA and the mechanisms involved are still unknown. Materials and Methods: In vivo experiments, using gait analysis, ELISA, micro-CT, and scanning electron microscopy (SEM), histological staining, immunohistological (IHC) and immunofluorescence (IF) staining, and atomic force microscopy (AFM) to assess OA progression after intraperitoneal injection of 5 and 15 mg/kg BA in an OA mouse model. In vitro experiments, caspase-1, IL-1ß, and the N-terminal fragment of gasdermin D (GSDMD-NT) were measured in bone marrow-derived macrophages (BMDMs) by using ELISA, western blot, and immunofluorescence staining. Results: We demonstrated that OA progression can be postponed with intraperitoneal injection of 5 and 15 mg/kg BA in an OA mouse model. Specifically, BA postponed DMM-induced cartilage deterioration, alleviated subchondral bone sclerosis, and relieved synovial inflammation. In vitro studies, the activated NLRP3 inflammasome produces mature IL-1ß by facilitating the cleavage of pro-IL-1ß, and BA could inhibit the activation of NLRP3 inflammasome in BMDMs. Conclusions: Taken together, our analyses revealed that BA attenuates OA via limiting NLRP3 inflammasome activation to decrease the IL-1ß maturation and secretion.


Subject(s)
Inflammasomes , Osteoarthritis , Animals , Mice , Betulinic Acid , Disease Models, Animal , Interleukin-1beta , NLR Family, Pyrin Domain-Containing 3 Protein , Osteoarthritis/drug therapy , Osteoarthritis/pathology
15.
Phys Chem Chem Phys ; 25(42): 28941-28947, 2023 Nov 01.
Article in English | MEDLINE | ID: mdl-37855655

ABSTRACT

Lattice dynamics plays a significant role in manipulating the unique physical properties of materials. In this work, femtosecond transient optical spectroscopy is used to investigate the generation mechanism and relaxation dynamics of coherent phonons in Fe1.14Te-a parent compound of chalcogenide superconductors. The reflectivity time series consist of the exponential decay component due to hot carriers and damped oscillations caused by the A1g phonon vibration. The vibrational frequency and dephasing time of the A1g phonons are obtained as a function of temperature. With increasing temperature, the phonon frequency decreases and can be well described with the anharmonicity model. Dephasing time is independent of temperature, indicating that the phonon dephasing is dominated by phonon-defect scattering. The impulsive stimulated Raman scattering mechanism is responsible for the coherent phonon generation. Owing to the resonance Raman effect, the maximum photosusceptibility of the A1g phonons occurs at 1.590 eV, corresponding to an electronic transition in Fe1.14Te.

16.
ACS Appl Mater Interfaces ; 15(35): 42094-42103, 2023 Sep 06.
Article in English | MEDLINE | ID: mdl-37625155

ABSTRACT

Cations can achieve excellent hydration lubrication at smooth interfaces under both microscale and macroscale conditions due to the boundary layer composed of hydration shells surrounding charges, but what about anions? Commonly used friction pairs are negatively charged at the solid/solution interface. Achieving anionic adsorption through constructing positively charged surfaces is a prerequisite for studying the hydration lubrication of anions. Here we report the hydration layer composed of anions adsorbed on the positively charged polymer/sapphire interface at acidic electrolyte solutions with pH below the isoelectric point, which contributes to the hydration lubrication of anions. Strongly hydrated anions (for the case of SO42-) exhibit stable superlubricity comparable to cations, with strikingly low boundary friction coefficient of 0.003-0.007 under contact pressures above 15 MPa without a running-in period. The hydration lubrication performance of anions is determined by both the ionic hydration strength and ion adsorption density based on the surface potential and tribological experiments. The results shed light on the role of anions in superlubricity and hydration lubrication, which may be relevant for understanding the lubrication mechanism and improving lubrication performance in acidic environments, for example, in acid pumps, sealing rings of compressors for handling acidic media, and processing devices of nuclear waste.

17.
Nature ; 620(7975): 904-910, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37558880

ABSTRACT

Arrestins have pivotal roles in regulating G protein-coupled receptor (GPCR) signalling by desensitizing G protein activation and mediating receptor internalization1,2. It has been proposed that the arrestin binds to the receptor in two different conformations, 'tail' and 'core', which were suggested to govern distinct processes of receptor signalling and trafficking3,4. However, little structural information is available for the tail engagement of the arrestins. Here we report two structures of the glucagon receptor (GCGR) bound to ß-arrestin 1 (ßarr1) in glucagon-bound and ligand-free states. These structures reveal a receptor tail-engaged binding mode of ßarr1 with many unique features, to our knowledge, not previously observed. Helix VIII, instead of the receptor core, has a major role in accommodating ßarr1 by forming extensive interactions with the central crest of ßarr1. The tail-binding pose is further defined by a close proximity between the ßarr1 C-edge and the receptor helical bundle, and stabilized by a phosphoinositide derivative that bridges ßarr1 with helices I and VIII of GCGR. Lacking any contact with the arrestin, the receptor core is in an inactive state and loosely binds to glucagon. Further functional studies suggest that the tail conformation of GCGR-ßarr governs ßarr recruitment at the plasma membrane and endocytosis of GCGR, and provides a molecular basis for the receptor forming a super-complex simultaneously with G protein and ßarr to promote sustained signalling within endosomes. These findings extend our knowledge about the arrestin-mediated modulation of GPCR functionalities.


Subject(s)
Receptors, Glucagon , beta-Arrestin 1 , beta-Arrestin 1/chemistry , beta-Arrestin 1/metabolism , Cell Membrane/metabolism , Endocytosis , Endosomes/metabolism , Glucagon/metabolism , Heterotrimeric GTP-Binding Proteins/metabolism , Ligands , Phosphatidylinositols/metabolism , Receptors, Glucagon/chemistry , Receptors, Glucagon/metabolism , Protein Binding
18.
Sci Adv ; 9(28): eadf3902, 2023 Jul 14.
Article in English | MEDLINE | ID: mdl-37436992

ABSTRACT

Water-based lubricants provide lubrication of rubbing surfaces in many technical, biological, and physiological applications. The structure of hydrated ion layers adsorbed on solid surfaces that determine the lubricating properties of aqueous lubricants is thought to be invariable in hydration lubrication. However, we prove that the ion surface coverage dictates the roughness of the hydration layer and its lubricating properties, especially under subnanometer confinement. We characterize different hydration layer structures on surfaces lubricated by aqueous trivalent electrolytes. Two superlubrication regimes are observed with friction coefficients of 10-4 and 10-3, depending on the structure and thickness of the hydration layer. Each regime exhibits a distinct energy dissipation pathway and a different dependence to the hydration layer structure. Our analysis supports the idea of an intimate relationship between the dynamic structure of a boundary lubricant film and its tribological properties and offers a framework to study such relationship at the molecular level.

19.
Adv Sci (Weinh) ; 10(27): e2303443, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37505392

ABSTRACT

The van der Waals (vdW) ferromagnet Fe3-δ GeTe2 has garnered significant research interest as a platform for skyrmionic spin configurations, that is, skyrmions and skyrmionic bubbles. However, despite extensive efforts, the origin of the Dzyaloshinskii-Moriya interaction (DMI) in Fe3-δ GeTe2 remains elusive, making it challenging to acquire these skyrmionic phases in a controlled manner. In this study, it is demonstrated that the Fe content in Fe3-δ GeTe2 has a profound effect on the crystal structure, DMI, and skyrmionic phase. For the first time, a marked increase in Fe atom displacement with decreasing Fe content is observed, transforming the original centrosymmetric crystal structure into a non-centrosymmetric symmetry, leading to a considerable DMI. Additionally, by varying the Fe content and sample thickness, a controllable transition between Néel-type skyrmions and Bloch-type skyrmionic bubbles is achieved, governed by a delicate interplay between dipole-dipole interaction and the DMI. The findings offer novel insights into the variable skyrmionic phases in Fe3-δ GeTe2 and provide the impetus for developing vdW ferromagnet-based spintronic devices.

20.
ACS Appl Mater Interfaces ; 15(30): 37093-37106, 2023 Aug 02.
Article in English | MEDLINE | ID: mdl-37488063

ABSTRACT

Various strategies have been developed to improve the applicability of hydrophobic pesticides for better effectiveness in agriculture. However, existing formulations of hydrophobic pesticides still suffer from complicated processing, abused organic solvents, indispensable surfactants, or inescapable ecotoxicity, which strictly limit their applications. Herein, a dynamic covalent bond tailored pesticide (fipronil) amphiphile is constructed to address the above issues, which accomplishes the nanodispersion, full wetting, and precise delivery without organic solvents, surfactants, and materials simultaneously. By introducing a hydrophilic ligand on the hydrophobic fipronil through an imine bond, the cleavable fipronil amphiphile (FPP) exhibits superior water solubility and can even self-assemble into micelles at higher concentrations, which can be directly applied in powder form without organic solvents. Attributed to the suitable hydrophilic/hydrophobic ratio, FPP achieves full wetting and effective deposition on superhydrophobic rice leaves without surfactants. Moreover, benefiting from the unique dynamic nature of the imine bond, FPP maintains good storage stability while sensitively releasing back to fipronil under the humidity and pH trigger, consequently implementing the precise delivery for nontarget Apis cerana and target Chilo suppressalis without materials. To our knowledge, this dynamic covalent bond tailored amphiphile strategy is the first idea that simultaneously takes the dispersibility, wettability, and responsiveness of hydrophobic pesticides into account, providing a possibility to control the entire journey of field application and even promising to be incorporated into the synthesis process, thus paving the way for modern sustainable agriculture.

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