The spontaneous assembly of uniform-sized globular entities into ordered arrays is a universal phenomenon observed for objects with diameters spanning a broad range of length scales. These extend from the atomic scale (10 cm), through molecular and macromolecular scales with proteins, synthetic low polymers, and colloidal crystals (∼10 cm), to the wavelength of visible light (∼10 cm). The associated concepts of sphere packing have had an influence in diverse fields ranging from pure geometrical analysis to architectural models or ideals. Self-assembly of atoms, supramolecules, or nanocrystals into ordered functional superstructures is a universal process and prevalent topic in science. About five billion years ago in the early solar system, highly uniform magnetite particles of a few hundred nanometers in size were assembled in 3D arrays.1 Thirty million years ago, silicate particles with submicrometer size were self-organized in the form of opal.2 Opal is colorless when composed of disordered silicate microparticles whereas it shows specific reflectivity when particles order in arrays. Nowadays, nanocrystals, characterized by a narrow size distribution and coated with alkyl chains to maintain their integrity, self-assemble to form crystallographic orders called supracrystals. Nanocrystals and supracrystals are arrangements of highly ordered atoms and nanocrystals, respectively. The morphologies of nanocrystals, supracrystals, and minerals are similar at various scales from nanometer to millimeter scale.3,4 Such suprastructures, which enable the design of novel materials, are expected to become one of the main driving forces in material research for the 21st century.5,6 Nanocrystals vibrate coherently in a supracrystal as atoms in a nanocrystal. Longitudinal acoustic phonons are detected in supracrystals as with atomic crystals, where longitudinal acoustic phonons propagate through coherent movements of atoms of the lattice out of their equilibrium positions. These vibrational properties show a full analogy with atomic crystals: In supracrystals, atoms are replaced by (uncompressible) nanocrystals and atomic bonds by coating agents (carbon chains), which act like mechanical springs holding together the nanocrystals. Electronic properties of very thick (more than a few micrometers) supracrystals reveal homogeneous conductance with the fingerprint of the isolated nanocrystal. Triangular single crystals formed by heat-induced (50 °C) coalescence of thin supracrystals deposited on a substrate as epitaxial growth of metal particles on a substrate with specific orientation produced by ultrahigh vacuum (UHV). Here we demonstrate that marked changes can occur in the chemical and physical properties of nanocrystals differing by their nanocrystallinity, that is, their crystalline structure. Furthermore, the properties (mechanical, growth processes) of supracrystals also change with the nanocrystallinity of the nanoparticles used as building blocks.
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http://dx.doi.org/10.1021/acs.accounts.7b00093 | DOI Listing |
Sci Rep
December 2024
Jihua Laboratory, Foshan, 528000, China.
Surface-enhanced Raman scattering (SERS) technology has attracted more and more attention due to its high sensitivity, low water interference, and quick measurement. Constructing high-performance SERS substrates with high sensitivity, uniformity and reproducibility is of great importance to put the SERS technology into practical application. In this paper, we report a simple fabrication process to construct dense silver-coated PMMA nanoparticles-on-a-mirror SRES substrates.
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December 2024
Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran.
In this study, we present the synthesis of a silver nanocomposite by utilizing a β-cyclodextrin (βCD) polymer anchored onto the surface of magnetic g-CN (referred to as g-CN-FeO/βCD-Ag). The structure and composition of the g-CN-FeO/βCD-Ag nanocomposite were thoroughly characterized using various techniques, including FT-IR, FE-SEM-EDS, TEM, TGA, XRD, ICP, and VSM. This catalytic system exhibited excellent selectivity in reducing nitro groups, even in the presence of other reactive functional groups, resulting in high yields ranging from 85 to 98%.
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December 2024
Laboratorio de Pesquisa em Cirurgia Toracica, Departamento de Cardiopneumologia, Instituto do Coracao (InCor), Hospital das Clinicas HCFMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.
Currently, the barrier to successful lung transplantation is ischemia and reperfusion injury, which can lead to the development of bronchiolitis obliterans. Paclitaxel and methotrexate are drugs known to inhibit cell proliferation and have anti-inflammatory effects, and the association of these drugs with cholesterol-rich nanoparticles has been shown to be beneficial in the treatment of other transplanted organs. Thirty-three male Sprague Dawley rats were divided into 3 groups: Basal group, no intervention; Control group, received only nanoparticles; Drug group, paclitaxel and methotrexate treatment.
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December 2024
Sustainability Solutions Research Lab, Faculty of Engineering, University of Pannonia, Egyetem Str. 10, Veszprém, 8200, Hungary.
Ensuring everyone enjoys healthy lifestyles and well-being at all ages, Progress has been made in increasing access to clean water and sanitation facilities and reducing the spread of epidemics and diseases. The synthesis of nano-particles (NPs) by using microalgae is a new nanobiotechnology due to the use of the biomolecular (corona) of microalgae as a capping and reducing agent for NP creation. This investigation explores the capacity of a distinct indigenous microalgal strain to synthesize silver nano-particles (AgNPs), as well as its effectiveness against multi-drug resistant (MDR) bacteria and its ability to degrade Azo dye (Methyl Red) in wastewater.
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December 2024
Department of Petroleum Engineering, Shahid Bahonar University of Kerman, Kerman, Iran.
Because a significant portion of oil remains in carbonate reservoirs, efficient techniques are essential to increase oil recovery from carbonate reservoirs. Wettability alteration is crucial for enhanced oil recovery (EOR) from oil-wet reservoirs. This study investigates the impact of different substances on the wettability of dolomite and calcite rocks.
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