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Articles de revues sur le sujet « NPs anisotropiche »

Auteur : Grafiati
Publié le 9 mars 2023
Mis à jour le 10 mars 2023

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1

Kerr, Melissa A., et Fei Yan. « Bromide-Assisted Anisotropic Growth of Gold Nanoparticles as Substrates for Surface-Enhanced Raman Scattering ». Journal of Spectroscopy 2016 (2016) : 1–8. http://dx.doi.org/10.1155/2016/3164247.

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We report herein a one-step synthesis of gold nanoparticles (Au NPs) of various shapes such as triangles, hexagons, and semispheres, using 5-hydroxyindoleacetic acid (5-HIAA) as the reducing agent in the presence of potassium bromide (KBr). Anisotropic Au NPs have received ever-increasing attention in various areas of research due to their unique physical and chemical properties. Numerous synthetic methods involving either top-down or bottom-up approaches have been developed to synthesize Au NPs with deliberately varied shapes, sizes, and configurations; however, the production of templateless, seedless, and surfactant-free singular-shaped anisotropic Au NPs remains a significant challenge. The concentrations of hydrogen tetrachloroaurate (HAuCl4), 5-HIAA, and KBr, as well as the reaction temperature, were found to influence the resulting product morphology. A detailed characterization of the resulting Au NPs was performed using ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy. The as-prepared Au NPs exhibited excellent surface-enhanced Raman scattering (SERS) properties, which make them very attractive for the development of SERS-based chemical and biological sensors.
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Fan, Jun-Bing, Yongyang Song, Hongfu Li, Jin-Peng Jia, Xinglin Guo et Lei Jiang. « Controllable drug release and effective intracellular accumulation highlighted by anisotropic biodegradable PLGE nanoparticles ». J. Mater. Chem. B 2, no 25 (2014) : 3911–14. http://dx.doi.org/10.1039/c3tb21726d.

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Zheng, Zijian, Jianxiang Shen, Jun Liu, Youping Wu, Liqun Zhang et Wenchuan Wang. « Tuning the visco-elasticity of elastomeric polymer materials via flexible nanoparticles : insights from molecular dynamics simulation ». RSC Advances 6, no 34 (2016) : 28666–78. http://dx.doi.org/10.1039/c6ra01827k.

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Galtier, S. « Wave turbulence in magnetized plasmas ». Nonlinear Processes in Geophysics 16, no 1 (16 février 2009) : 83–98. http://dx.doi.org/10.5194/npg-16-83-2009.

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Abstract. The paper reviews the recent progress on wave turbulence for magnetized plasmas (MHD, Hall MHD and electron MHD) in the incompressible and compressible cases. The emphasis is made on homogeneous and anisotropic turbulence which usually provides the best theoretical framework to investigate space and laboratory plasmas. The solar wind and the coronal heating problems are presented as two examples of application of anisotropic wave turbulence. The most important results of wave turbulence are reported and discussed in the context of natural and simulated magnetized plasmas. Important issues and possible spurious interpretations are also discussed.
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Treumann, R. A., et W. Baumjohann. « Brief Communication : Weibel, Firehose and Mirror mode relations ». Nonlinear Processes in Geophysics 21, no 1 (22 janvier 2014) : 143–48. http://dx.doi.org/10.5194/npg-21-143-2014.

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Abstract. Excitation of Weibel magnetic fields in an initially non-magnetized though anisotropic plasma may trigger other low-frequency instabilities fed by pressure anisotropy. It is shown that under Weibel-like stable conditions the Weibel-like thermal fluctuation magnetic field allows for restricted Firehose-mode growth. In addition, low-frequency Whistlers can also propagate in the plasma under certain anisotropic conditions. When the Weibel-like mode becomes unstable, Firehose instability ceases but Mirror modes take over. This will cause bubble structures in the Weibel-like field in addition to filamentation.
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Park, Byung Hyun, Ji Hyun Lee, Jae Hwan Jung, Seung Jun Oh, Doh C. Lee et Tae Seok Seo. « A centrifuge-based stepwise chemical loading disc for the production of multiplex anisotropic metallic nanoparticles ». RSC Advances 5, no 3 (2015) : 1846–51. http://dx.doi.org/10.1039/c4ra13778g.

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Osipov, Aleksander Aleksandrovich, et Denis Anatolievich Skobeev. « Liquid metal technology of synthesis of ALOOH anisotropic nanostructured aerogel ». Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika 2016, no 4 (décembre 2016) : 91–101. http://dx.doi.org/10.26583/npe.2016.4.09.

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Wang, Xujie, Zhenlong Dou, Chi Zhang, FangFang Deng, XiaoLin Lu, ShuangShuang Wang, Li Zhou et Tao Ding. « Polarization-controlled anisotropy in hybrid plasmonic nanoparticles ». Nanophotonics 11, no 5 (27 janvier 2022) : 1003–9. http://dx.doi.org/10.1515/nanoph-2021-0691.

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Abstract Anisotropy has played a critical role in many material systems, but its controllable creation and modulation have been a long-lasting challenge for the scientific communities. Polarization-addressed anisotropy appears more attractive among all approaches due to its excellent controllability, simplicity, and accuracy, but only a limited number of material systems are applicable for such a concept, which are largely focused on oriented growth. Here, we establish a polarization-dependent anisotropic etching system made of Au@oligomer core–shell nanoparticles (NPs). As the oligomer coatings can be photochemically degraded via two-photon photolithography, the plasmonic near-field enhancement supported by the Au NP cores renders much faster degradation of the oligomer shells along the polarization, resulting in anisotropic Au@oligomer hybrid NPs. Such shape anisotropy leads to polarization-dependent photoluminescence with embedded dyes of methylene blue, which can be used as single-particle-based polarization detector. The oligomer lobes capped at the sides of the Au NP can also function as a protection agent for anisotropic photochemical growth of Au NPs, which evolve into Au nanorods and mushrooms with controlled irradiation time. Such polarization-directed etching of oligomer shells has unique advantages of high local-selectivity, controllability, and versatility for on-chip nanofabrication, which opens many new opportunities for integrated nanophotonic devices.
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Pandey, Puran, Mao Sui, Ming-Yu Li, Quanzhen Zhang, Eun-Soo Kim et Jihoon Lee. « Shape transformation of self-assembled Au nanoparticles by the systematic control of deposition amount on sapphire (0001) ». RSC Advances 5, no 81 (2015) : 66212–20. http://dx.doi.org/10.1039/c5ra07631e.

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The shape and size dependent optical, physical and chemical properties of isotropic and anisotropic gold nanoparticles (Au NPs) have attracted significant research interest for their application in various optoelectronic devices.
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Antonova, I. V., D. V. Marin, Vladimir A. Volodin, V. A. Skuratov, J. Jedrzejewski et I. Balberg. « Anisotropic Strain – Anisotropic Heating Engineering for Silicon Nanocrystals in SiO2 ». Solid State Phenomena 156-158 (octobre 2009) : 523–28. http://dx.doi.org/10.4028/www.scientific.net/ssp.156-158.523.

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In the present paper we discuss effects due to high-energy ion bombardment of SiO2 layers with embedded Si nanocrystals (NCs), such as the formation of new Si NCs in such layers, amorphization of previously existing NCs, modification of NC size distribution, and modification of optical and electrical properties of NCs. These effects are identified as resulting from anisotropic strain - anisotropic heating in NCs-SiO2 layers under ion irradiation.
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Krajczewski, Jan, Robert Ambroziak, Sylwia Turczyniak-Surdacka et Małgorzata Dziubałtowska. « WO3 Nanopores Array Modified by Au Trisoctahedral NPs : Formation, Characterization and SERS Application ». Materials 15, no 23 (6 décembre 2022) : 8706. http://dx.doi.org/10.3390/ma15238706.

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The WO3 nanopores array was obtained by an anodization method in aqueous solution with addition of F- ions. Several factors affecting the final morphology of the samples were tested such as potential, time, and F- concentrations. The morphology of the formed nanopores arrays was examined by SEM microscopy. It was found that the optimal time of anodization process is in the range of 0.5–1 h. The nanopores size increased with the increasing potential. The XPS measurements do not show any contamination by F- on the surface, which is common for WOx samples formed by an anodization method. Such a layer was successfully modified by anisotropic gold trisoctahedral NPs of various sizes. The Au NPs were obtained by seed-mediated growth method. The shape and size of Au NPs was analysed by TEM microscopy and optical properties by UV-VIS spectroscopy. It was found that the WO3-Au platform has excellent SERS activity. The R6G molecules could be detected even in the range of 10−9 M.
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González-Rubio, Guillermo, Jesús Mosquera, Vished Kumar, Adrián Pedrazo-Tardajos, Pablo Llombart, Diego M. Solís, Ivan Lobato et al. « Micelle-directed chiral seeded growth on anisotropic gold nanocrystals ». Science 368, no 6498 (25 juin 2020) : 1472–77. http://dx.doi.org/10.1126/science.aba0980.

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Surfactant-assisted seeded growth of metal nanoparticles (NPs) can be engineered to produce anisotropic gold nanocrystals with high chiroptical activity through the templating effect of chiral micelles formed in the presence of dissymmetric cosurfactants. Mixed micelles adsorb on gold nanorods, forming quasihelical patterns that direct seeded growth into NPs with pronounced morphological and optical handedness. Sharp chiral wrinkles lead to chiral plasmon modes with high dissymmetry factors (~0.20). Through variation of the dimensions of chiral wrinkles, the chiroptical properties can be tuned within the visible and near-infrared electromagnetic spectrum. The micelle-directed mechanism allows extension to other systems, such as the seeded growth of chiral platinum shells on gold nanorods. This approach provides a reproducible, simple, and scalable method toward the fabrication of NPs with high chiral optical activity.
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13

Tsubokura, Y., M. Miyamoto, K. Ikeda, T. Nakamura et T. Takahashi. « Anisotropic superconductivity in κ-(BEDT-TTF)2Cu(NCS)2 ». Synthetic Metals 70, no 1-3 (mars 1995) : 913–14. http://dx.doi.org/10.1016/0379-6779(94)02697-w.

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Horkaew, Paramate, et Tanawat Kwanpak. « Structural adaptive anisotropic NAS-RIF for biomedical image restoration ». Journal of Applied Engineering Science 17, no 3 (2019) : 284–94. http://dx.doi.org/10.5937/jaes17-21031.

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DePaoli, Damon, Alicja Gasecka, Mohamed Bahdine, Jean M. Deschenes, Laurent Goetz, Jimena Perez-Sanchez, Robert P. Bonin, Yves De Koninck, Martin Parent et Daniel C. Côté. « Anisotropic light scattering from myelinated axons in the spinal cord ». Neurophotonics 7, no 01 (10 mars 2020) : 1. http://dx.doi.org/10.1117/1.nph.7.1.015011.

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Usón, Isabel, Ehmke Pohl, Thomas R. Schneider, Zbigniew Dauter, Arno Schmidt, Hans-Joachim Fritz et George M. Sheldrick. « 1.7 Å structure of the stabilized REIv mutant T39K. Application of local NCS restraints ». Acta Crystallographica Section D Biological Crystallography 55, no 6 (1 juin 1999) : 1158–67. http://dx.doi.org/10.1107/s0907444999003972.

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The X-ray structure of the T39K mutant of the variable domain of a human immunoglobulin κ light chain has been determined at room temperature to 1.7 Å resolution with a conventional R factor of 0.182. T39K crystallizes in the triclinic space group P1 [a = 35.4 (1), b = 40.1 (1), c = 43.1 (1) Å, α = 66.9 (1), β = 85.4 (1), γ = 73.8 (1)°]. The unit-cell contains two monomers, related by a non-crystallographic twofold axis. The use of a novel type of local non-crystallographic symmetry restraints on related isotropic displacement parameters and 1–4 distances as incorporated in the refinement program SHELXL improves the model and quality of the maps, but local differences between both monomers in areas subject to different packing contacts can still be observed. 12 overall anisotropic scaling parameters were refined. These may have compensated for the difficulties in accurately scaling single rotation axis image-plate data from a triclinic crystal, because of the scarcity of common equivalent reflections. The final model has been used to perform a number of tests on anisotropic scaling, non-crystallographic symmetry, anisotropic refinement, determination of standard uncertainties and bulk solvent correction. It is remarkable that removal of the NCS restraints from the final model caused R free to increase. These tests clarify the strategies for optimum use of SHELXL for refinement at medium as opposed to atomic resolution.
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Tran, Van Tan, Dong Kyu Lee, Jeonghyo Kim, Jaewook Lee, Lemma Teshome Tufa, De Pham-Cong, Chang-Seok Kim et Jaebeom Lee. « Porosity-controllable magnetoplasmonic nanoparticles and their assembled arrays ». Nanoscale 12, no 15 (2020) : 8453–65. http://dx.doi.org/10.1039/d0nr01178a.

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The porosity of the Fe3O4 shells coating on Ag NPs is well controlled using an anisotropic etching method, providing an effective approach to modulate the chemical and optical properties of the colloids as well as their 1D and 2D assembled arrays.
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JEONG, Byeong-Hyeon, et Ji-Sang PARK*. « Calculation of the Stacking Fault Energy by Using the Anisotropic Next-Nearest Neighbor Ising Model ». New Physics : Sae Mulli 70, no 8 (31 août 2020) : 630–36. http://dx.doi.org/10.3938/npsm.70.630.

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Kaur, Rajpreet, Poonam Khullar et Anita Gupta. « Protein-Protein Interactions Followed by in-Situ Synthesis of Gold Nanoparticles ». ECS Transactions 107, no 1 (24 avril 2022) : 16375–90. http://dx.doi.org/10.1149/10701.16375ecst.

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Protein-protein interaction (PPI) plays an important role in various biochemical processes. Various binary mixtures of industrially important zein have been blended with rice and wheat proteins to expand their biological applicability. Zein-rice, zein-hard wheat, and zein-soft wheat mixtures show different behavior toward in vitro synthesis of Au NPs. This can also be explained by the TEM, FESEM, and DLS studies of PPI-Au NPs mixtures. Zein-rice-Au NPs mixture showed their mutual favorable interaction with high colloidal stability and high reduction ability towards nucleating Au NPs. This may be due to both hydrophobic and hydrophilic interaction of zein-rice PPI, which resulted in regular and shape-controlled Au NPs. In the case of zein-wheat PPI interaction, lesser hydrophobic interaction resulted in the incomplete unfolding of wheat protein and demixing of wheat protein with zein protein to anisotropic and irregular Au NPs. The study of these interactions will lead to the development of therapeutic centers toward different diseases and their environmental applications.
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Kuo, Shuo-Hsiu, Po-Ting Wu, Jing-Yin Huang, Chin-Pao Chiu, Jiashing Yu et Mei-Yi Liao. « Fabrication of Anisotropic Cu Ferrite-Polymer Core-Shell Nanoparticles for Photodynamic Ablation of Cervical Cancer Cells ». Nanomaterials 10, no 12 (4 décembre 2020) : 2429. http://dx.doi.org/10.3390/nano10122429.

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In this work we developed methylene blue-immobilized copper-iron nanoparticles (MB-CuFe NPs) through a facile one-step hydrothermal reaction to achieve a better phototherapeutic effect. The Fe/Cu ratio of the CuFe NPs was controllable by merely changing the loading amount of iron precursor concentration. The CuFe NPs could serve as a Fenton catalyst to convert hydrogen peroxide (H2O2) into reactive oxygen species (ROS), while the superparamagnetic properties also suggest magnetic resonance imaging (MRI) potential. Furthermore, the Food and Drug Administration (FDA)-approved MB photosensitizer could strongly adsorb onto the surface of CuFe NPs to facilitate the drug delivery into cells and improve the photodynamic therapy at 660 nm via significant generation of singlet oxygen species, leading to enhanced cancer cell-damaging efficacy. An MTT (thiazolyl blue tetrazolium bromide) assay proved the low cytotoxicity of the CuFe NPs to cervical cancer cells (HeLa cells), namely above 80% at 25 ppm of the sample dose. A slight dissolution of Cu and Fe ions from the CuFe NPs in an acidic environment was obtained, providing direct evidence for CuFe NPs being degradable without the risk of long-term retention in the body. Moreover, the tremendous photo-to-thermal conversion of CuFe NPs was examined, which might be combined with photodynamic therapy (PDT) for promising development in the depletion of cancer cells after a single pulse of deep-red light irradiation at high laser power.
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Lovejoy, S., et D. Schertzer. « Scaling and multifractal fields in the solid earth and topography ». Nonlinear Processes in Geophysics 14, no 4 (2 août 2007) : 465–502. http://dx.doi.org/10.5194/npg-14-465-2007.

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Abstract. Starting about thirty years ago, new ideas in nonlinear dynamics, particularly fractals and scaling, provoked an explosive growth of research both in modeling and in experimentally characterizing geosystems over wide ranges of scale. In this review we focus on scaling advances in solid earth geophysics including the topography. To reduce the review to manageable proportions, we restrict our attention to scaling fields, i.e. to the discussion of intensive quantities such as ore concentrations, rock densities, susceptibilities, and magnetic and gravitational fields. We discuss the growing body of evidence showing that geofields are scaling (have power law dependencies on spatial scale, resolution), over wide ranges of both horizontal and vertical scale. Focusing on the cases where both horizontal and vertical statistics have both been estimated from proximate data, we argue that the exponents are systematically different, reflecting lithospheric stratification which – while very strong at small scales – becomes less and less pronounced at larger and larger scales, but in a scaling manner. We then discuss the necessity for treating the fields as multifractals rather than monofractals, the latter being too restrictive a framework. We discuss the consequences of multifractality for geostatistics, we then discuss cascade processes in which the same dynamical mechanism repeats scale after scale over a range. Using the binomial model first proposed by de Wijs (1951) as an example, we discuss the issues of microcanonical versus canonical conservation, algebraic ("Pareto") versus long tailed (e.g. lognormal) distributions, multifractal universality, conservative and nonconservative multifractal processes, codimension versus dimension formalisms. We compare and contrast different scaling models (fractional Brownian motion, fractional Levy motion, continuous (in scale) cascades), showing that they are all based on fractional integrations of noises built up from singularity basis functions. We show how anisotropic (including stratified) models can be produced simply by replacing the usual distance function by an anisotropic scale function, hence by replacing isotropic singularities by anisotropic ones.
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JEONG, Byeong-Hyeon, et Ji-Sang PARK*. « Erratum : Calculation of the Stacking Fault Energy by Using the Anisotropic Next-Nearest Neighbor Ising Model ». New Physics : Sae Mulli 70, no 11 (30 novembre 2020) : 1021. http://dx.doi.org/10.3938/npsm.70.1021.

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CHAICHENETS, LEONID, et NIKOLAOS PATTAKOS. « THE GLOBAL CAUCHY PROBLEM FOR THE NLS WITH HIGHER ORDER ANISOTROPIC DISPERSION ». Glasgow Mathematical Journal 63, no 1 (12 décembre 2019) : 45–53. http://dx.doi.org/10.1017/s0017089519000491.

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AbstractWe use a method developed by Strauss to obtain global well-posedness results in the mild sense and existence of asymptotic states for the small data Cauchy problem in modulation spaces ${M}^s_{p,q}(\mathbb{R}^d)$, where q = 1 and $s\geq0$ or $q\in(1,\infty]$ and $s>\frac{d}{q'}$ for a nonlinear Schrödinger equation with higher order anisotropic dispersion and algebraic nonlinearities.
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Gagnon, J. S., S. Lovejoy et D. Schertzer. « Multifractal earth topography ». Nonlinear Processes in Geophysics 13, no 5 (16 octobre 2006) : 541–70. http://dx.doi.org/10.5194/npg-13-541-2006.

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Abstract. This paper shows how modern ideas of scaling can be used to model topography with various morphologies and also to accurately characterize topography over wide ranges of scales. Our argument is divided in two parts. We first survey the main topographic models and show that they are based on convolutions of basic structures (singularities) with noises. Focusing on models with large numbers of degrees of freedom (fractional Brownian motion (fBm), fractional Levy motion (fLm), multifractal fractionally integrated flux (FIF) model), we show that they are distinguished by the type of underlying noise. In addition, realistic models require anisotropic singularities; we show how to generalize the basic isotropic (self-similar) models to anisotropic ones. Using numerical simulations, we display the subtle interplay between statistics, singularity structure and resulting topographic morphology. We show how the existence of anisotropic singularities with highly variable statistics can lead to unwarranted conclusions about scale breaking. We then analyze topographic transects from four Digital Elevation Models (DEMs) which collectively span scales from planetary down to 50 cm (4 orders of magnitude larger than in previous studies) and contain more than 2×108 pixels (a hundred times more data than in previous studies). We use power spectra and multiscaling analysis tools to study the global properties of topography. We show that the isotropic scaling for moments of order ≤2 holds to within ±45% down to scales ≈40 m. We also show that the multifractal FIF is easily compatible with the data, while the monofractal fBm and fLm are not. We estimate the universal parameters (α, C1) characterizing the underlying FIF noise to be (1.79, 0.12), where α is the degree of multifractality (0≤α≤2, 0 means monofractal) and C1 is the degree of sparseness of the surface (0≤C1, 0 means space filling). In the same way, we investigate the variation of multifractal parameters between continents, oceans and continental margins. Our analyses show that no significant variation is found for (α, C1) and that the third parameter H, which is a degree of smoothing (higher H means smoother), is variable: our estimates are H=0.46, 0.66, 0.77 for bathymetry, continents and continental margins. An application we developped here is to use (α, C1) values to correct standard spectra of DEMs for multifractal resolution effects.
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Ouillon, G., D. Sornette et C. Castaing. « Organisation of joints and faults from 1-cm to 100-km scales revealed by optimized anisotropic wavelet coefficient method and multifractal analysis ». Nonlinear Processes in Geophysics 2, no 3/4 (31 décembre 1995) : 158–77. http://dx.doi.org/10.5194/npg-2-158-1995.

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Abstract. The classical method of statistical physics deduces the macroscopic behaviour of a system from the organization and interactions of its microscopical constituents. This kind of problem can often be solved using procedures deduced from the Renormalization Group Theory, but in some cases, the basic microscopic rail are unknown and one has to deal only with the intrinsic geometry. The wavelet analysis concept appears to be particularly adapted to this kind of situation as it highlights details of a set at a given analyzed scale. As fractures and faults generally define highly anisotropic fields, we defined a new renormalization procedure based on the use of anisotropic wavelets. This approach consists of finding an optimum filter will maximizes wavelet coefficients at each point of the fie] Its intrinsic definition allows us to compute a rose diagram of the main structural directions present in t field at every scale. Scaling properties are determine using a multifractal box-counting analysis improved take account of samples with irregular geometry and finite size. In addition, we present histograms of fault length distribution. Our main observation is that different geometries and scaling laws hold for different rang of scales, separated by boundaries that correlate well with thicknesses of lithological units that constitute the continental crust. At scales involving the deformation of the crystalline crust, we find that faulting displays some singularities similar to those commonly observed in Diffusion- Limited Aggregation processes.
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Geiseler, Bianca, Marko Miljevic, Philipp Müller et Ljiljana Fruk. « Phototriggered Production of Reactive Oxygen Species by TIO2Nanospheres and Rods ». Journal of Nanomaterials 2012 (2012) : 1–9. http://dx.doi.org/10.1155/2012/708519.

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We present the study of reactive oxygen species production under the light irradiation of two different types of TiO2nanocrystals. Both TiO2spheric NPs and anisotropic nanorods were investigated using activation of the horseradish peroxidase enzyme and subsequent substrate oxidation into a fluorescent product. The influence of the surface ligand dopamine was also explored to shed more light on the effect of catechol binders on the photoactivity of TiO2species.
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Yordanova, E., J. Bergman, G. Consolini, M. Kretzschmar, M. Materassi, B. Popielawska, M. Roca-Sogorb, K. Stasiewicz et A. W. Wernik. « Anisotropic scaling features and complexity in magnetospheric-cusp : a case study ». Nonlinear Processes in Geophysics 12, no 6 (14 septembre 2005) : 817–25. http://dx.doi.org/10.5194/npg-12-817-2005.

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Abstract. Magnetospheric cusps are high-latitude regions characterized by a highly turbulent plasma, playing a special role in the solar wind-magnetosphere interaction. Here, using POLAR satellite magnetic field vector measurements we investigate the anisotropic scaling features of the magnetic field fluctuations in the northern cusp region. Our results seem to support the hypothesis of a 2D-MHD turbulent scenario which is consequence of a strong background magnetic field. The observed turbulent fluctuations reveal a high degree of complexity, which might be due to the interplay of many competing scales. A discussion of our findings in connection with the complex scenario proposed by Chang et al. (2004) is provided.
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Hau, L. N., et B. J. Wang. « On MHD waves, fire-hose and mirror instabilities in anisotropic plasmas ». Nonlinear Processes in Geophysics 14, no 5 (3 septembre 2007) : 557–68. http://dx.doi.org/10.5194/npg-14-557-2007.

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Abstract. Temperature or pressure anisotropies are characteristic of space plasmas, standard magnetohydrodynamic (MHD) model for describing large-scale plasma phenomena however usually assumes isotropic pressure. In this paper we examine the characteristics of MHD waves, fire-hose and mirror instabilities in anisotropic homogeneous magnetized plasmas. The model equations are a set of gyrotropic MHD equations closed by the generalized Chew-Goldberger-Low (CGL) laws with two polytropic exponents representing various thermodynamic conditions. Both ions and electrons are allowed to have separate plasma beta, pressure anisotropy and energy equations. The properties of linear MHD waves and instability criteria are examined and numerical examples for the nonlinear evolutions of slow waves, fire-hose and mirror instabilities are shown. One significant result is that slow waves may develop not only mirror instability but also a new type of compressible fire-hose instability. Their corresponding nonlinear structures thus may exhibit anticorrelated density and magnetic field perturbations, a property used for identifying slow and mirror mode structures in the space plasma environment. The conditions for nonlinear saturation of both fire-hose and mirror instabilities are examined.
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Finnegan, S. M., M. E. Koepke et D. J. Knudsen. « A two-fluid model describing the finite-collisionality, stationary Alfvén wave in anisotropic plasma ». Nonlinear Processes in Geophysics 15, no 6 (9 décembre 2008) : 957–64. http://dx.doi.org/10.5194/npg-15-957-2008.

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Abstract. The stationary inertial Alfvén (StIA) wave (Knudsen, 1996) was predicted for cold, collisionless plasma. The model was generalized (Finnegan et al., 2008) to include nonzero values of electron and ion collisional resistivity and thermal pressure. Here, the two-fluid model is further generalized to include anisotropic thermal pressure. A bounded range of values of parallel electron drift velocity is found that excludes periodic stationary Alfvén wave solutions. This exclusion region depends on the value of the local Alfvén speed VA, plasma beta perpendicular to the magnetic field β⊥ and electron temperature anisotropy.
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NAM, Soon-Kwon, et Joon-Ho CHOI*. « Dose Analyses for the Anisotropic Analytical and the Pencil-Beam Convolution Algorithms in Large-Field Intensity-Modulated Radiation Therapy ». New Physics : Sae Mulli 67, no 10 (31 octobre 2017) : 1231–35. http://dx.doi.org/10.3938/npsm.67.1231.

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Schilling, Martin, Paul Ziemann, Zaoli Zhang, Johannes Biskupek, Ute Kaiser et Ulf Wiedwald. « Orientation of FePt nanoparticles on top of a-SiO2/Si(001), MgO(001) and sapphire(0001) : effect of thermal treatments and influence of substrate and particle size ». Beilstein Journal of Nanotechnology 7 (21 avril 2016) : 591–604. http://dx.doi.org/10.3762/bjnano.7.52.

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Texture formation and epitaxy of thin metal films and oriented growth of nanoparticles (NPs) on single crystal supports are of general interest for improved physical and chemical properties especially of anisotropic materials. In the case of FePt, the main focus lies on its highly anisotropic magnetic behavior and its catalytic activity, both due to the chemically ordered face-centered tetragonal (fct) L10 phase. If the c-axis of the tetragonal system can be aligned normal to the substrate plane, perpendicular magnetic recording could be achieved. Here, we study the orientation of FePt NPs and films on a-SiO2/Si(001), i.e., Si(001) with an amorphous (a-) native oxide layer on top, on MgO(001), and on sapphire(0001) substrates. For the NPs of an approximately equiatomic composition, two different sizes were chosen: “small” NPs with diameters in the range of 2–3 nm and “large” ones in the range of 5–8 nm. The 3 nm thick FePt films, deposited by pulsed laser deposition (PLD), served as reference samples. The structural properties were probed in situ, particularly texture formation and epitaxy of the specimens by reflection high-energy electron diffraction (RHEED) and, in case of 3 nm nanoparticles, additionally by high-resolution transmission electron microscopy (HRTEM) after different annealing steps between 200 and 650 °C. The L10 phase is obtained at annealing temperatures above 550 °C for films and 600 °C for nanoparticles in accordance with previous reports. On the amorphous surface of a-SiO2/Si substrates we find no preferential orientation neither for FePt films nor nanoparticles even after annealing at 630 °C. On sapphire(0001) supports, however, FePt nanoparticles exhibit a clearly preferred (111) orientation even in the as-prepared state, which can be slightly improved by annealing at 600–650 °C. This improvement depends on the size of NPs: Only the smaller NPs approach a fully developed (111) orientation. On top of MgO(001) the effect of annealing on particle orientation was found to be strongest. From a random orientation in the as-prepared state observed for both, small and large FePt NPs, annealing at 650 °C for 30 min reorients the small particles towards a cube-on-cube epitaxial orientation with a minor fraction of (111)-oriented particles. In contrast, large FePt NPs keep their as-prepared random orientation even after doubling the annealing period at 650 °C to 60 min.
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Canals, M., et M. Ayt Ougoudal. « Percolation on anisotropic media, the Bethe lattice revisited. Application to fracture networks ». Nonlinear Processes in Geophysics 4, no 1 (31 mars 1997) : 11–18. http://dx.doi.org/10.5194/npg-4-11-1997.

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Abstract. A bond-percolation model based on the Bethe Lattice is presented. This model handles anisotropic and multiscale situations where, typically, the bond probability is non unique and depends on the sites it connects. The model is governed by a set of non-linear equations which are solved numerically. As a result, the structure of the network is obtained: strengths of the backbone, dead-end roads and finite clusters. Percolation thresholds and cluster sizes are also obtained. Application to fissured media is presented and random simulations of 3D distributions of fractures show the good accuracy of the model.
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Marsch, E. « On resonant interactions of ions with plasma waves in a reduced quasi-linear theory ». Nonlinear Processes in Geophysics 9, no 2 (30 avril 2002) : 69–74. http://dx.doi.org/10.5194/npg-9-69-2002.

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Abstract. Based on quasi-linear theory (involving pitch angle scattering), the resonant interactions between ions and waves in an anisotropic multi-component plasma are discussed. In particular, electromagnetic Alfvén and ion-cyclotron waves propagating along or obliquely to the magnetic field are considered. A set of reduced (with respect to the perpendicular velocity component) quasi-linear diffusion equations is derived, involving reduced 1-D velocity distribution functions (VDFs), as they occur in wave dispersion relations. A 2-D model VDF can be constructed when using the Gaussian approximation. Wave-particle heating and acceleration rates are calculated.
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Borgogno, D., T. Passot et P. L. Sulem. « Magnetic holes in plasmas close to the mirror instability ». Nonlinear Processes in Geophysics 14, no 4 (9 juillet 2007) : 373–83. http://dx.doi.org/10.5194/npg-14-373-2007.

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Abstract. Non-propagating magnetic hole solutions in anisotropic plasmas near the mirror instability threshold are investigated in numerical simulations of a fluid model that incorporates linear Landau damping and finite Larmor radius corrections calculated in the gyrokinetic approximation. This FLR-Landau fluid model reproduces the subcritical mirror bifurcation recently identified on the Vlasov-Maxwell system, both by theory and numerics. Stable magnetic hole solutions that display a polarization different from that of Hall-MHD solitons are indeed obtained slighlty below threshold, while magnetic patterns and spatio-temporal chaos emerge when the system is maintained in a mirror unstable regime.
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35

Galperin, B., S. Sukoriansky, N. Dikovskaya, P. L. Read, Y. H. Yamazaki et R. Wordsworth. « Anisotropic turbulence and zonal jets in rotating flows with a β-effect ». Nonlinear Processes in Geophysics 13, no 1 (4 avril 2006) : 83–98. http://dx.doi.org/10.5194/npg-13-83-2006.

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Abstract. Numerical studies of small-scale forced, two-dimensional turbulent flows on the surface of a rotating sphere have revealed strong large-scale anisotropization that culminates in the emergence of quasi-steady sets of alternating zonal jets, or zonation. The kinetic energy spectrum of such flows also becomes strongly anisotropic. For the zonal modes, a steep spectral distribution, E(n)=CZ (Ω/R)2 n-5, is established, where CZ=O(1) is a non-dimensional coefficient, Ω is the angular velocity, and R is the radius of the sphere, respectively. For other, non-zonal modes, the classical, Kolmogorov-Batchelor-Kraichnan, spectral law is preserved. This flow regime, referred to as a zonostrophic regime, appears to have wide applicability to large-scale planetary and terrestrial circulations as long as those are characterized by strong rotation, vertically stable stratification and small Burger numbers. The well-known manifestations of this regime are the banded disks of the outer planets of our Solar System. Relatively less known examples are systems of narrow, subsurface, alternating zonal jets throughout all major oceans discovered in state-of-the-art, eddy-permitting simulations of the general oceanic circulation. Furthermore, laboratory experiments recently conducted using the Coriolis turntable have basically confirmed that the lateral gradient of ''planetary vorticity'' (emulated via the topographic β-effect) is the primary cause of the zonation and that the latter is entwined with the development of the strongly anisotropic kinetic energy spectrum that tends to attain the same zonal and non-zonal distributions, −5 and , respectively, in both the slope and the magnitude, as the corresponding spectra in other environmental conditions. The non-dimensional coefficient CZ in the −5 spectral law appears to be invariant, , in a variety of simulated and natural flows. This paper provides a brief review of the zonostrophic regime. The review includes the discussion of the physical nature, basic mechanisms, scaling laws and universality of this regime. A parameter range conducive to its establishment is identified, and collation of laboratory and naturally occurring flows is presented through which the zonostrophic regime manifests itself in the real world.
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Beaulieu, A., H. Gaonac'h et S. Lovejoy. « Anisotropic scaling of remotely sensed drainage basins : the differential anisotropy scaling technique ». Nonlinear Processes in Geophysics 14, no 4 (6 juillet 2007) : 337–50. http://dx.doi.org/10.5194/npg-14-337-2007.

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Abstract. We investigate the statistical properties of dendritic drainage areas from diverse geological environments (Deception Canyon, Utah and the Loess Plateau, China) using narrow band visible ASTER satellite images. We show that from 240 m to 7680 m, the isotropic (angle integrated) energy spectra E(k) of all the fields closely follow a power law form: E(k)∝k−β where k is a wave number and β a scale invariant exponent. In spite of this good isotropic scaling, images with very similar β's and similar isotropic multifractal exponents have distinct textures; we suggest that the differences are primarily due to anisotropy, which is nevertheless scaling. We develop the new "Differential Anisotropy Scaling" technique to characterize this scale-by-scale (differential) anisotropy and we test it on simulated anisotropic scaling fields. The method gives useful characterizations of the scale by scale anisotropy irrespective of whether or not the analyzed field is scaling. When the anisotropy is not too strong, the parameters can be interpreted as scale invariant anisotropy exponents. Viewed as a method of estimating these exponents, it has the advantage of relying on two linear regressions rather than on complex higher dimensional nonlinear ones. When applied to dendritic drainage basins we find that they have distinct anisotropies characterized by differential anisotropy stretching and rotation parameters as well as by a distinct absolute anisotropy at the reference scale of 960 m. Our new method allows us to statistically distinguish, not only between two geologically different drainage basins (the China Loess Plateau and Utah Deception Canyon), but also between different regions of the same China drainage system.
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Ma, Qiannan, et Weihua Zhu. « Computational studies of energetics, electronic structure, and vibrational spectra of PETN nanoparticles ». Canadian Journal of Chemistry 99, no 1 (janvier 2021) : 63–71. http://dx.doi.org/10.1139/cjc-2020-0210.

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The density functional tight binding method was used to explore the energetics, electronic structure, and vibrational spectra of pentaerythritol tetranitrate (PETN) nanoparticles (NPs). The surface energy of the PETN NP is anisotropic and its extra energy decreases with the increase of size. The energy bands of the NPs are significantly expanded and the band gaps are narrowed, thus reducing the stability due to nanometer size effect. The surface of the NP is mainly covered by the NO2 group. The high-energy surface may play a role in triggering chemical decomposition. The vibration frequencies of the PETN NPs present a wider distribution than those of the gas and solid phase PETN, which will increase the probability of energy transfer to the molecules in the system and promote the decomposition of PETN. Our results provide a basic understanding from a molecular perspective to the energy properties of nano explosives.
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Moschou, Panagiotis N., Eugene I. Savenkov, Elena A. Minina, Kazutake Fukada, Salim Hossain Reza, Emilio Gutierrez-Beltran, Victoria Sanchez-Vera et al. « EXTRA SPINDLE POLES (Separase) controls anisotropic cell expansion in Norway spruce (Picea abies ) embryos independently of its role in anaphase progression ». New Phytologist 212, no 1 (27 mai 2016) : 232–43. http://dx.doi.org/10.1111/nph.14012.

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Mjølhus, E., E. Helmersen et D. F. DuBois. « Geometric aspects of HF driven Langmuir turbulence in the ionosphere ». Nonlinear Processes in Geophysics 10, no 1/2 (30 avril 2003) : 151–77. http://dx.doi.org/10.5194/npg-10-151-2003.

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Abstract. The geometric aspects of HF-generated Langmuir turbulence in the ionosphere and its detection by radars are theoretically discussed in a broad approach, including local modelling (damped and driven Zakharov system), basic parametric instabilities, polarization and strength of the driving electric field, and radar configurations. Selected examples of numerical results from the local model are presented and discussed in relation to recent experiments, with emphasis on recent experiments at the EISCAT facilities. Anisotropic aspects of the cavitation process in the magnetized plasma are exhibited. Basic processes of cascades and cavitation are by now well identified in these experiments, but a few problems of the detailed agreement between theory and experiments are pointed out.
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40

Schaeffer, N., et P. Cardin. « Rossby-wave turbulence in a rapidly rotating sphere ». Nonlinear Processes in Geophysics 12, no 6 (4 novembre 2005) : 947–53. http://dx.doi.org/10.5194/npg-12-947-2005.

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Abstract. We use a quasi-geostrophic numerical model to study the turbulence of rotating flows in a sphere, with realistic Ekman friction and bulk viscous dissipation. The forcing is caused by the destabilization of an axisymmetric Stewartson shear layer, generated by differential rotation, resulting in a forcing at rather large scales. The equilibrium regime is strongly anisotropic and inhomogeneous but exhibits a steep m-5 spectrum in the azimuthal (periodic) direction, at scales smaller than the injection scale. This spectrum has been proposed by Rhines for a Rossby wave turbulence. For some parameter range, we observe a turbulent flow dominated by a large scale vortex located in the shear layer, reminding us of the Great Red Spot of Jupiter.
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41

Pattanayak, Satarupa, Abhishek Swarnkar, Amiya Priyam et Gopal M. Bhalerao. « Citrate–hydrazine hydrogen-bonding driven single-step synthesis of tunable near-IR plasmonic, anisotropic silver nanocrystals : implications for SERS spectroscopy of inorganic oxoanions ». Dalton Trans. 43, no 31 (2014) : 11826–33. http://dx.doi.org/10.1039/c4dt01091d.

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Anisotropic silver nanocrystals (NCs) having Vis-to-NIR plasmon tunability have been synthesized by tailoring the hydrogen-bonding interactions between a mild stabilizer (citrate) and a mild reductant (hydrazine hydrate).
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42

Dallari, Caterina, Riccardo Innocenti, Elena Lenci, Andrea Trabocchi, Francesco Saverio Pavone et Caterina Credi. « Design and Synthesis of Novel Raman Reporters for Bioorthogonal SERS Nanoprobes Engineering ». International Journal of Molecular Sciences 23, no 10 (16 mai 2022) : 5573. http://dx.doi.org/10.3390/ijms23105573.

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Surface-enhanced Raman spectroscopy (SERS) exploiting Raman reporter-labeled nanoparticles (RR@NPs) represents a powerful tool for the improvement of optical bio-assays due to RRs’ narrow peaks, SERS high sensitivity, and potential for multiplexing. In the present work, starting from low-cost and highly available raw materials such as cysteamine and substituted benzoic acids, novel bioorthogonal RRs, characterized by strong signal (103 counts with FWHM < 15 cm−1) in the biological Raman-silent region (>2000 cm−1), RRs are synthesized by implementing a versatile, modular, and straightforward method with high yields and requiring three steps lasting 18 h, thus overcoming the limitations of current reported procedures. The resulting RRs’ chemical structure has SH-pendant groups exploited for covalent conjugation to high anisotropic gold-NPs. RR@NPs constructs work as SERS nanoprobes demonstrating high colloidal stability while retaining NPs’ physical and vibrational properties, with a limit of detection down to 60 pM. RR@NPs constructs expose carboxylic moieties for further self-assembling of biomolecules (such as antibodies), conferring tagging capabilities to the SERS nanoprobes even in heterogeneous samples, as demonstrated with in vitro experiments by transmembrane proteins tagging in cell cultures. Finally, thanks to their non-overlapping spectra, we envision and preliminary prove the possibility of exploiting RR@NPs constructs simultaneously, aiming at improving current SERS-based multiplexing bioassays.
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Hu, Zhongying, Kohei Inoue et Kiichi Urahama. « Anisotropic Minimum Spanning Tree for Generating Dendritic Line Drawings and Terrain-like NPR ». Journal of The Institute of Image Information and Television Engineers 68, no 5 (2014) : J221—J223. http://dx.doi.org/10.3169/itej.68.j221.

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Idrees, Sumra, Zahoor Ahmad, Tashfeen Akhtar, Muhammad Aziz Choudhary, Muhammad Aftab Rafiq et Arshad Mehmood. « Facile chemical strategy to synthesize Ag@polypyrrole microarrays and investigating its anisotropic effect on polymer conductivity ». Materials Science-Poland 37, no 4 (1 décembre 2019) : 563–69. http://dx.doi.org/10.2478/msp-2019-0068.

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AbstractA facile chemical approach was developed to fabricate microarrays (MAs) of Ag@polypyrrole nanocables (NCs). The strategy involved crosslinking the NCs by tetraethoxy silane (TEOS) under continuous pulse sonication without using a substrate. The material was characterized by scanning electron microscope (SEM) coupled with EDX, which revealed the longitudinal interconnections within the nanocables and creating unidirectional alignment in the form of MAs. FT-IR and Raman spectroscopy was employed to characterize the encapsulating polymer as polypyrrole (ppy) around Ag nanowires (NWs). The microarrays produced red shift in surface plasmon resonance (SPR) of Ag NWs, and drastically improved the thermal stability and conductivity of encasing ppy. It has imparted anisotropic conductivity effect on ppy which resulted in sharp decrease in resistivity from 8.35 × 1010 Ω to 2.449 Ω, when NCs were isolated and crosslinked into MAs form, respectively. The drastic decrease in resistivity of ppy was due to the anisotropic effect produced by the MAs format of NWs.
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Guo, Yating, Feng Gao, Pan Huang, Rong Wu, Wanying Gu, Jing Wei, Fangze Liu et Hongbo Li. « Light-Emitting Diodes Based on Two-Dimensional Nanoplatelets ». Energy Material Advances 2022 (7 février 2022) : 1–24. http://dx.doi.org/10.34133/2022/9857943.

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Colloidal semiconductor nanocrystals (NCs) attract significant interest in recent years due to their narrow and tunable emission wavelength in the visible range, as well as high photoluminescence quantum yield (PLQY), which are highly desired in display technologies. The high-quality NCs have been recognized as vital luminescent materials in realizing next-generation display devices. With further development, NCs with near-unity PLQY have been successfully synthesized through engineering of the core/shell heterostructure. However, as the external quantum efficiency (EQE) of the nanocrystal light-emitting diodes (LEDs) approaches the theoretical limit of about 20%, the low out-coupling factor proposes a challenge of enhancing the performance of a device when using the spherical QDs. Hence, the anisotropic NCs like nanoplatelets (NPLs) are proposed as promising solutions to improve the performance of nanocrystal LEDs. In this review, we will summarize the synthetic strategies of two-dimensional (2D) NPLs at first. Then, we will introduce fundamental concepts of LEDs, the main approaches to realize LEDs based on nanoplatelets, and the recent progress. Finally, the challenges and opportunities of LEDs based on anisotropic NCs are also presented.
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Kaur, Manpreet, et Anu Kalia. « Role of salt precursors for the synthesis of zinc oxide nanoparticles and in imparting variable antimicrobial activity ». Journal of Applied and Natural Science 8, no 2 (1 juin 2016) : 1039–48. http://dx.doi.org/10.31018/jans.v8i2.918.

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Synthesis of nanoparticles (NPs) having unique potentials and properties is of great importance in nanotechnology. The NP synthesis techniques may include the wet chemistry to microbial incubation reduction methods. This work reports generation of ZnO NPs by identical preparation including incubation of different zinc salts i.e. zinc acetate, zinc chloride and zinc sulphate as precursors with cell free extracts of Bacillus circulans MTCC 7906 (Bc7906) and Pleurotus florida (Pf). The synthesized NPs exhibited variation in their absorption peaks in UV-Vis spectra which appeared at 275 nm, 325 nm and 375 nm with P. florida for the three salt precursors respectively while the Bc7906 generated ZnO NPs showed peaks between 300-350 nm. A variation in ZnO NP morphology ranged from 50 to 120 nm in size and spherical, oval, cylindrical to trigonal anisotropic in shape by transmission EM. Further, the rough and corrugated surface topography of ZnO NPs was observed in Scanning EM. The % weight for Zn element surface composition as recorded by SEM-EDS was observed to be highest for zinc acetate (2.34%) and zinc sulphate (7.54 %) on microbial synthesis from Bc7906 and Pf respectively. The antimicrobial potential of the synthesized ZnO NPs on human pathogenic and plant beneficial bacteria was tested and it was observed to be highest for microbially synthesized ZnO NPs using zinc acetate (15 mm) and zinc sulphate (14 mm) as salt precursors @ 10 ppm. This is the first report on differential antimicrobial behavior of ZnO NPs on human pathogenic and plant beneficial microbes.
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Chang, T. « An example of resonances, coherent structures and topological phase transitions - the origin of the low frequency broadband spectrum in the auroral zone ». Nonlinear Processes in Geophysics 8, no 3 (30 juin 2001) : 175–80. http://dx.doi.org/10.5194/npg-8-175-2001.

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Abstract. We consider the phenomena of intermittent turbulence in magnetized space plasmas from the point of view of topological phase transitions involving the merging and interactions of anisotropic coherent structures. The stochastic behaviour of these coherent plasma structures can undergo complex changes as the dynamic system evolves, similar to those commonly observed in (first and second order) equilibrium phase transitions. When conditions are favourable, such topological entities can evolve into a state of forced and/or self-organized criticality (FSOC). As an example, we apply these ideas to the understanding of the origin of the commonly observed broadband power-law low frequency electric field spectral densities and the characteristic filamentary current structures in the auroral zone. The broadband turbulence can provide efficient resonant energization of the ionospheric oxygen ions.
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48

Hennes, M., A. Lotnyk et S. G. Mayr. « Plasma-assisted synthesis and high-resolution characterization of anisotropic elemental and bimetallic core–shell magnetic nanoparticles ». Beilstein Journal of Nanotechnology 5 (14 avril 2014) : 466–75. http://dx.doi.org/10.3762/bjnano.5.54.

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Magnetically anisotropic as well as magnetic core–shell nanoparticles (CS-NPs) with controllable properties are highly desirable in a broad range of applications. With this background, a setup for the synthesis of heterostructured magnetic core–shell nanoparticles, which relies on (optionally pulsed) DC plasma gas condensation has been developed. We demonstrate the synthesis of elemental nickel nanoparticles with highly tunable sizes and shapes and Ni@Cu CS-NPs with an average shell thickness of 10 nm as determined with scanning electron microscopy, high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy measurements. An analytical model that relies on classical kinetic gas theory is used to describe the deposition of Cu shell atoms on top of existing Ni cores. Its predictive power and possible implications for the growth of heterostructured NP in gas condensation processes are discussed.
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Pralong, A. « Oscillations in critical shearing, application to fractures in glaciers ». Nonlinear Processes in Geophysics 13, no 6 (12 décembre 2006) : 681–93. http://dx.doi.org/10.5194/npg-13-681-2006.

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Abstract. Many evidences of oscillations accompanying the acceleration of critical systems have been reported. These oscillations are usually related to discrete scale invariance properties of the systems and exhibit a logarithmic periodicity. In this paper we propose another explanation for these oscillations in the case of shearing fracture. Using a continuum damage model, we show that oscillations emerge from the anisotropic properties of the cracks in the shearing fracture zone. These oscillations no longer exhibit a logarithmic but rather a power-law periodicity. The power-periodic oscillation is a more general formulation. Its reduces to a log-periodic oscillation when the exponent of the power-law equals one. We apply this model to fit the measured displacements of unstable ice masses of hanging glaciers for which data are available. Results show that power-periodic oscillations adequately fit the observations.
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Elbert, Katherine C., William Zygmunt, Thi Vo, Corbin M. Vara, Daniel J. Rosen, Nadia M. Krook, Sharon C. Glotzer et Christopher B. Murray. « Anisotropic nanocrystal shape and ligand design for co-assembly ». Science Advances 7, no 23 (juin 2021) : eabf9402. http://dx.doi.org/10.1126/sciadv.abf9402.

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The use of nanocrystal (NC) building blocks to create metamaterials is a powerful approach to access emergent materials. Given the immense library of materials choices, progress in this area for anisotropic NCs is limited by the lack of co-assembly design principles. Here, we use a rational design approach to guide the co-assembly of two such anisotropic systems. We modulate the removal of geometrical incompatibilities between NCs by tuning the ligand shell, taking advantage of the lock-and-key motifs between emergent shapes of the ligand coating to subvert phase separation. Using a combination of theory, simulation, and experiments, we use our strategy to achieve co-assembly of a binary system of cubes and triangular plates and a secondary system involving two two-dimensional (2D) nanoplates. This theory-guided approach to NC assembly has the potential to direct materials choices for targeted binary co-assembly.
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