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Facile synthesis of metal-polyphenol-formaldehyde coordination polymer colloidal nanoparticles with sub-50 nm for T_(1)-weighted magnetic resonance imaging

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Chinese Chemical Letters 2021年第2期32卷 842-848页

作者： Jing Qin Guohai Liang Bingxi Feng Gen Wang Na Wu Yonghui Deng Ahmed AElzatahry Abdulaziz Alghamdi Yongxi Zhao Jing Wei The Key Laboratory of Biomedical Information Engineering of Ministry of Education School of Life Science and TechnologyXi'an Jiaotong UniversityXi'an 710049China College of Biophotonics South China Normal UniversityGuangzhou 510631China Department of Chemistry Fudan UniversityShanghai 200433China Materials Science and Technology Program College of Arts and SciencesQatar UniversityPO Box 2713DohaQatar Department of Chemistry College of ScienceKing Saud UniversityP.O.Box 2455Riyadh 11451Saudi Arabia

Plant polyphenol-based coordination polymers(CPs) with ultra-small particle size and tailorable compositions are highly desired in biomedical applicatio ns,but their synthesis is still challenging due to the sophisticated coordination assembly process and unavoidable self-oxidation polymerization of polyphenol. He rein,a general ligand covalent-modification mediated coordination assembly strategy is proposed for the synthesis of water-dispersible CPs with tunable metal species(e.g., Gd,Cu,Ni,Zn,Fe)and ultra-small diameter(8.6-37.8 nm) using nontoxic plant polyphenol(e.g..tannic acid,gallic acid) as a polymerizable *** molecules react with formaldehyde firstly,which can effectively retard the oxidation induced self-polymerization of polyphenol and lead to the formation of metal ions containing CPs colloidal *** ultrafine nanoparticles with stably chelated metal io ns are highly water dispersible and thus advantageous for *** an example,ultra-small Gd contained CPs exhibit higher longitudinal relaxivity(r_(1)=25.5 L mmol^(-1) s^(-1)) value with low r2/r1(1.19) than clinically used Magnevist(Gd-DTPA,r1=3.7 L mmol^(-1) s^(-1)) .Due to the enhanced permeability and retention effect,they can be further used as a positive contrast agent for T1-weighted MR imaging of tumour.

关键词： Coordination polymer Nanoparticle Self-assembly Plant polyphenol Contrast agent

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Creating Continuously Graded Microstructures with Electric Fields via Locally Altering Grain Boundary Complexions

arXiv

引用

arXiv 2023年

作者： Yan, Qizhang Hu, Chongze Luo, Jian Department of Nano and Chemical Engineering University of California San Diego La Jolla CA92093 United States Program in Materials Science and Engineering University of California San Diego La Jolla CA92093 United States Department of Aerospace Engineering and Mechanics University of Alabama TuscaloosaAL35487 United States

Tailoring microstructures represents a daunting goal in materials science. Here, an innovative proposition is to utilize grain boundary (GB) complexions (a.k.a. interfacial phases) to manipulate microstructural evolution, which is challenging to control via only temperature and doping. Herein, we use ZnO as a model system to tailor microstructures using applied electric fields as a new knob to control GB structures locally via field-driven stoichiometry (defects) polarization. Specifically, continuously graded microstructures are created under applied electric fields. By employing aberration-corrected scanning transmission electron microscopy (AC STEM) in conjunction with density functional theory (DFT) and ab initio molecular dynamics (AIMD), we discover cation-deficient, oxygen-rich GBs near the anode with enhanced GB diffusivities. In addition, the field-driven redistribution of cation vacancies is deduced from a defect chemistry model, and subsequently verified by spatially resolved photoluminescence spectroscopy. This bulk stoichiometry polarization leads to preferential formation of cation-deficient (oxidized) GBs near the anode to gradually promote grain growth towards the anode. This mechanism can be utilized to create continuously graded microstructures without abnormal grain growth typically observed in prior studies. This study exemplifies a case of tailoring microstructural evolution via altering GB complexions locally with applied electric fields, and it enriches fundamental GB science. © 2023, CC BY.

关键词： Density functional theory

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Supplementary information for "Low-loss silicon nitride Kerr-microresonators fabricated with metallic etch masks via metal lift-off"

arXiv

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arXiv 2025年

作者： Colación, Gabriel M. Rukh, Lala Buck, Franco Drake, Tara E. Optical Science & Engineering Program University of New Mexico AlbuquerqueNM87106 United States Center for High Technology Materials University of New Mexico AlbuquerqueNM87106 United States Department of Physics & Astronomy University of New Mexico AlbuquerqueNM87106 United States

Stoichiometric silicon nitride has emerged as a widely used integratedphotonic material owing to its high index of refraction, nonlinear opticalproperties, and broad transparency window spanning visible to mid-IRfrequencies. However, silicon nitride is generally more resistant to reactiveion etching than are typical etch masks made of polymer-based resist. Thisnecessitates resist layers that are significantly thicker than the siliconnitride and results in mask patterns which are tall and narrow. Thesehigh-aspect-ratio patterns inhibit the plasma transport of reactive ionetching, which leads to difficulties in accurately reproducing dimensions andcreating well-defined, vertical waveguide sidewalls. In this work, we overcomethese challenges by developing a metallic etch mask that provides a 30:1nitride-to-metal etch rate ratio, representing a near 20-fold reduction in therequired mask thickness. We demonstrate the quality of this technique byetching microring resonators with near-vertical waveguide sidewalls andintrinsic quality factors of over 1 million. Leveraging the low optical loss ofour resonators, we generate optical frequency combs with more than an octave ofbandwidth and dual dispersive waves. These results establish metal lift-off asa viable and easy-to-implement technique capable of producing low optical losswaveguides. © 2025, CC BY.

关键词： Aspect ratio

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Effects of MXenes (Ti3C2Tx) deposition by drop casting on the fretting wear of structural concrete

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Wear 2025年 570卷

作者： Silva, Cristiane Arpino Gonçalves, Margarete R.F. Rosenkranz, Andreas Hammes, Gisele Costa, Henara Lillian Universidade Federal de Pelotas Materials Science and Engineering Graduate Program Rua Gomes Carneiro 1 Porto RS Pelotas Brazil University of Chile Department of Chemical Engineering Biotechnology and Materials Avenida Beauchef 851 Santiago Chile Universidade Federal de Santa Catarina LabMat Rua Delfino Conti s/n. Bloco B Trindade SC Florianópolis Brazil Universidade Federal do Rio Grande School of Engineering Av. Itália km 8 Bairro Carreiros RS Rio Grande Brazil

In civil engineering, concrete is the most widely used material due to the availability of its components. Research on tribology of semi-rigid structural systems is important in civil engineering, as the initially rigid contact between concrete and metallic elements can generate micromovement, resulting in wear due to fretting and possible cracks. Recently, a new family of 2D metal carbide and nitride nanosheets called MXenes has stood out in tribological applications due to their layered structure, which provides self-lubricating and reinforcing properties, but they are costly and difficult to produce in large scale, making their use in civil engineering challenging, despite encouraging results from the literature. To overcome this, the present work proposed surface deposition of MXenes by drop-casting (involving very small amounts of Mxenes) to control fretting wear between concrete and steel. One and five applications were deposited from a dispersion at a concentration of approximately 0.4 mg/mL of MXenes in isopropanol. Fretting tests were carried out on concrete (with and without MXenes deposition) against steel counterbodies for a total stroke of 200 μm under different speeds (0.2 and 2 mm/s) and times (5 and 30 min). The results showed that the friction coefficients obtained in the fretting tests did not present a statistically significant difference when using Mxenes either as a reinforcement in the concrete or deposited by drop casting. The wear rates obtained from the fretting tests demonstrated that, for the lower speed, no significant difference could be confirmed for the modified concretes in either the 5 min or the 30 min tests. On the other hand, in the condition of speed = 2 mm/s and time = 5 min, the wear rate for one application of MXenes by dropcasting was lower than the reference. With a higher speed and 30-min test, a greater effect on the wear rate occurred, which may be the result of tribochemical effects in the contact. It is clear that, in t

关键词： Tribology

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Effect of Processing Conditions on Short-Range Order and Mechanical Properties of the NbMoTaW Multi-Principal Element Alloy

SSRN

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SSRN 2023年

作者： Zheng, Hui Nibbelink, Luke Li, Xiang-Guo Zuo, Yunxing Chen, Chi Ong, Shyue Ping Department of NanoEngineering University of California San Diego 9500 Gilman Dr Mail Code 0448 La Jolla CA92093-0448 United States Materials Science and Engineering University of California San Diego 9500 Gilman Dr Mail Code 0448 La Jolla CA92093-0448 United States

Refractory multi-principal element alloys (RMPEAs) are promising candidates for high-temperature applications due to their exceptional mechanical properties. In this work, we investigate the effect of processing conditions on the observed short-range order (SRO) in the NbMoTaW RMPEA, and the consequent effect on mechanical properties, using Monte Carlo/molecular dynamics (MC/MD) simulations with a highly accurate machine learning interatomic potential. We demonstrate that SRO is maximized at an intermediate temperature range of 800K-1000K. A higher SRO results in higher stacking fault energies (SFEs), anti-phase boundary energies (APBEs) and critical resolved shear stresses (CRSS). We also show that Nb segregation in polycrystalline NbTaMoW is also present at intermediate annealing temperatures, and this Nb segregation can have the effect of retarding grain growth even at high temperatures. © 2023, The Authors. All rights reserved.

关键词： Molecular dynamics

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Piezo-Flexocatalysis of Single-Atom Pt-Loaded Graphitic Carbon Nitride

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Small Methods 2024年第7期8卷 e2301287页

作者： Wang, Yu Teng Lin, Hsun-Yen Chen, Yu-Ching Lin, Yan-Gu Wu, Jyh Ming Department of Materials Science and Engineering National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan Program in Prospective Functional Materials Industry National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan National Synchrotron Radiation Research Center 101 Hsin-Ann Road Hsinchu Science Park Hsinchu300092 Taiwan High Entropy Materials Center National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan

This study develops a single-atom Pt-loaded graphitic carbon nitride (SA-Pt/CN) and evaluates its piezo-flexocatalytic properties by conducting a hydrogen evolution reaction (HER) and Rhodamine B (RB) dye degradation test under ultrasonic vibration in the dark. SA-Pt/CN has a hydrogen gas yield of 1283.8 µmol g−1 h−1, which is 23.3 times higher than that of pristine g-C3N4. Moreover, SA-Pt/CN enhances the dye degradation reaction rate by ≈2.3 times compared with the pristine sample. SA-Pt/CN exhibits lattice distortion and strain gradient enlargement caused by the single atom Pt at the N sites of g-C3N4, which disrupts the symmetric structure and contributes to the enhancement of piezoelectric and flexoelectric polarization. As far as it is known, this is the first study to investigate the piezo-flexocatalytic reaction of SA-Pt/CN without light irradiation and provides new insights into single-atom piezocatalysts. © 2023 Wiley-VCH GmbH.

关键词： Degradation

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Formation of Oxygen Vacancies in Cr³⁺-Doped Hydroxyapatite Nanofibers and Their Role in Generating Paramagnetism

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Biomedical materials and Devices 2025年第1期3卷 529-544页

作者： Carrera, Karime Huerta, Verónica Orozco, Victor Matutes, José Urbieta, Ana Fernández, Paloma Martínez, Fabián Graeve, Olivia A. Herrera, Manuel Centro de Nanociencias y Nanotecnología Universidad Nacional Autónoma de México BC Ensenada C.P. 22800 Mexico Centro de Investigación en Materiales Avanzados Chih. Chihuahua C.P. 31136 Mexico Departamento de Física de Materiales Universidad Complutense de Madrid Madrid C.P. 28040 Spain Program in Materials Science and Engineering University of California San Diego La Jolla 92093-0411 CA United States Department of Mechanical and Aerospace Engineering University of California San Diego La Jolla 92093-0411 CA United States

We demonstrate that doping hydroxyapatite (HAp) with Cr3+ ions induces oxygen vacancies, contributing to paramagnetism. Cathodoluminescence and photoluminescence analyses reveal increased oxygen vacancy formation in O... 详细信息

We demonstrate that doping hydroxyapatite (HAp) with Cr³⁺ ions induces oxygen vacancies, contributing to paramagnetism. Cathodoluminescence and photoluminescence analyses reveal increased oxygen vacancy formation in OH- and PO43- groups with rising Cr³⁺ concentrations, highlighted by stronger cathodoluminescence emissions at 2.57 and 2.95 eV and the photoluminescence emission at 3.32 eV. Raman spectroscopy shows new modes at 900 and 970 cm⁻¹, indicating distortion of the v₁ vibrational mode due to Cr³⁺ substitution at Ca(II) sites of the HAp lattice. X-ray photoelectron spectroscopy confirms Cr³⁺ in the HAp:Cr. Magnetometry reveals a shift from diamagnetism in pure HAp to increasing paramagnetism in HAp:Cr with higher Cr³⁺ content, achieving 0.0460 emu/g at 10 kOe with concentrations higher than 2.9 at.%. This paramagnetism is attributed to Cr³⁺ ions and singly ionized oxygen vacancies VO′ aligning along an external magnetic field, with VO′ formation linked to PO43- replacement by PO32- in HAp. © The Author(s) 2024.

关键词： Cathodoluminescence Cr3+ Hydroxyapatite Oxygen vacancies Paramagnetism

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Corrigendum to “Fermi energy engineering of enhanced plasticity in high-entropy carbides” [Acta Materialia, 276 (2024) 120117]

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Acta Materialia 2025年 282卷

作者： Kenneth Vecchio Stefano Curtarolo Kevin Kaufmann Tyler J. Harrington Corey Oses Cormac Toher Department of NanoEngineering University of California San Diego La Jolla CA 92093 USA Department of Mechanical Engineering and Materials Science Center for Extreme Materials Duke University Durham NC 27708 USA

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Frequency-dependent Phonon-mediated Unidirectional Magnetoresistance in a Metal on an Insulator with Highly Nonequilibrium Magnons

arXiv

引用

arXiv 2022年

作者： Sullivan, Sean E. Lee, Hwijong Weathers, Annie Shi, Li Materials Science and Engineering Program The University of Texas at Austin AustinTX78712 United States Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States

Heavy metal (HM)/magnet bilayers host many magnetoresistances (MR) and spin caloritronic effects. Here we show that the spin Peltier effect and electron-phonon scattering produce much larger unidirectional MR of an HM on a magnetic insulator than existing theories that neglect the interplay between MR and spin caloritronic effects. By accounting for local nonequilibrium in both the magnon chemical potential and temperature, our analytical model attributes the observed frequency dependence of the spin Peltier MR and the spin Seebeck effect to the reduction of the thermal penetration depth, which approaches the 1-μm scale magnon spin diffusion length at high frequencies. © 2022, CC BY.

关键词： Heavy metals

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Claw coloration in the fiddler crab Leptuca uruguayensis has no correlation with male quality

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Current Zoology 2025年第1期71卷 109-123页

作者： Zackary A.Graham Jonatas de Jesus Florentino Samuel P.Smithers Joao C.T.Menezes Jose Eduardo de Carvalho Alexandre V.Palaoro Department of Organismal Biology Ecologyand Zoo ScienceWest Liberty University208 University DriveWest LibertyWV 26074USA Programa de Pós-Graduacao em Ecologia Universidade de São PauloRua do Mataon 321Trav.14ButantãDistrictSao PauloSP 05508-090Brazil Department of Psychology Northeastern University360 Huntington AvenueBostonMA 02115USA Organismic and Evolutionary Biology Graduate Program University of Massachusetts Amherst230 Stockbridge RoadAmherstMA 01003USA Departamento de Ecologia e Biologia Evolutiva Universidade Federal de Sao PauloRua Sao Nicolaun 210Centro DistrictDiademaSP 09972-270Brazil Department of Materials Science and Engineering Clemson University515 Calhoun DrClemsonSC 29634USA Departamento de Zoologia Universidade Federal do ParanáAvenida Coronel Francisco H.dos Santosn 100Jardim das Américas DistrictCuritibaPR 82590-300Brazil

Sexual selection is thought to play a major role in the evolution of color due to the correlation between a signaler’s physiological state and the displayed *** such,researchers often investigate how color correlates to the quality of the ***,research on the relationship between color and individual quality is often taxonomically limited and researchers typically investigate how color phenotypes relate to one index of quality,such as a linear measure of body ***,we investigated the relationship among body size,claw size,claw muscle mass,lipid content,and the color of the claw in male fiddler crabs(Leptuca uruguayensis)which wield an exaggerated claw that varies in color from brown to *** hypothesized that if the color was correlated to one or more indices of male quality,the color displayed on the claws of male *** could be under sexual *** found *** claw color varies substantially among the individuals we ***,we did not find a correlation between claw color and indices of quality;neither brightness nor hue correlated to the indices of quality we *** findings suggest that claw color in *** is unlikely to have evolved to signal quality,but may instead function as a species identity or as a non-indicator sexual signal.

关键词： animal coloration animal communication animal signals Decapoda non-indicator sexual signal sexual selection

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