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Appl. Nano, Volume 5, Issue 2 (June 2024) – 5 articles

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24 pages, 5830 KiB  
Article
Experimental Characterization of Hydronic Air Coil Performance with Aluminum Oxide Nanofluids of Three Concentrations
by Roy Strandberg, Dustin Ray and Debendra K. Das
Appl. Nano 2024, 5(2), 84-107; https://doi.org/10.3390/applnano5020008 - 11 Jun 2024
Viewed by 236
Abstract
This paper presents the continuation of experimental investigations conducted by the present authors to measure and compare the thermal and fluid dynamic performance of a residential hydronic air coil using nanofluids. The prior experiments were limited to testing only one volumetric concentration (1%) [...] Read more.
This paper presents the continuation of experimental investigations conducted by the present authors to measure and compare the thermal and fluid dynamic performance of a residential hydronic air coil using nanofluids. The prior experiments were limited to testing only one volumetric concentration (1%) of aluminum oxide (Al2O3) nanofluid. They compared it with the base fluid, a 60% ethylene glycol/40% water mixture by mass (60% EG). The original tests revealed some deficiencies in the experimental setup, which was subsequently revised and improved. This paper summarizes the results of experiments from the improved test bed using three concentrations of Al2O3 nanofluids: 1, 2, and 3% volumetric concentrations prepared with an average particle size of 45 nm in a 60% EG dispersion. The test bed in these experiments simulates a small air handling system typical of heating, ventilation, and air conditioning (HVAC) applications in cold regions. Entering conditions for the air and liquid were selected to emulate typical commercial air handling systems operating in cold climates. Contrary to previous findings, our test results revealed that nanofluids did not perform as well as expected. Prior predictions from many analytical and numerical studies had promised significant performance gain. The performance of the 1% nanofluid was generally equal to that of the base fluid under identical inlet conditions. However, the performance of the 2% and 3% nanofluids was considerably lower than that of the base fluid. The higher concentration nanofluids exhibited heat rates up to 14.6% lower than the 60% EG and up to 44.3% lower heat transfer coefficient. The 1% Al2O3/60% EG exhibited a 100% higher pressure drop across the coil than the base fluid, considering equal heat output. This performance degradation was attributed to the inability to maintain nanofluid dispersion stability, agglomeration, and subsequent decline in the thermophysical properties. Full article
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12 pages, 7441 KiB  
Article
Black TiO2 and Oxygen Vacancies: Unraveling the Role in the Thermal Anatase-to-Rutile Transformation
by Mattia Allieta, Mauro Coduri and Alberto Naldoni
Appl. Nano 2024, 5(2), 72-83; https://doi.org/10.3390/applnano5020007 - 3 May 2024
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Abstract
Understanding the role of oxygen vacancies in the phase transformation of metal oxide nanomaterials is fundamental to design more efficient opto-electronic devices for a variety of applications, including sensing, spintronics, photocatalysis, and photo-electrochemistry. However, the structural mechanisms behind the phase transformation in reducible [...] Read more.
Understanding the role of oxygen vacancies in the phase transformation of metal oxide nanomaterials is fundamental to design more efficient opto-electronic devices for a variety of applications, including sensing, spintronics, photocatalysis, and photo-electrochemistry. However, the structural mechanisms behind the phase transformation in reducible oxides remain poorly described. Here, we compare P25 and black TiO2 during the thermal anatase-to-rutile transformation using in situ synchrotron powder diffraction. The precise measurement of the phase fractions, unit cell parameters, and Ti-O bond sheds light on the phase transformation dynamics. Notably, we observe distinct temperature-dependent shifts in the relative phase fractions of anatase and rutile in both materials highlighting the role of the oxygen vacancy in promoting the phase transformation. We employ bond valence concepts for structural modeling, revealing unique trends in temperature evolution of Ti-O distances of black rutile, confirming that this TiO2 phase is preferentially reduced over anatase. These findings not only enhance our understanding of phase transitions in TiO2 but also open new ways for the design of advanced photocatalytic materials through targeted phase control. Full article
(This article belongs to the Collection Feature Papers for Applied Nano)
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14 pages, 6874 KiB  
Article
Influence of Baccharis salicifolia Extract on Iron Oxide Nanoparticles in MCM-41@IONP and Its Application in Room-Temperature-Fabricated Metal–Insulator–Semiconductor Diodes
by Gerardo Miguel Bravo de Luciano, Blanca Susana Soto-Cruz, Anabel Romero-López, Yesmin Panecatl-Bernal, José Alberto Luna-López and Miguel Ángel Domínguez-Jiménez
Appl. Nano 2024, 5(2), 58-71; https://doi.org/10.3390/applnano5020006 - 26 Apr 2024
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Abstract
This work presents the green synthesis of iron oxide nanoparticles (IONPs) using Baccharis salicifolia extract and their incorporation in mesoporous silica MCM-41, obtaining an MCM-41@IONP composite. The MCM-41@IONP composite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nitrogen adsorption and desorption, [...] Read more.
This work presents the green synthesis of iron oxide nanoparticles (IONPs) using Baccharis salicifolia extract and their incorporation in mesoporous silica MCM-41, obtaining an MCM-41@IONP composite. The MCM-41@IONP composite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nitrogen adsorption and desorption, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The use of the natural reducing agent Baccharis salicifolia resulted in nanoparticles with an average size of 31 nm. Furthermore, we showcase the application of the MCM-41@IONP nanocomposite in a metal–insulator–semiconductor (MIS) diode, which was fabricated at room temperature. The current–voltage and capacitance–voltage curves of the MIS diode were carefully measured and subjected to detailed analysis. The results demonstrate the potential utility of MCM-41@IONP nanocomposite-based MIS diodes, suggesting their applicability in the design of biosensors or as discrete components in electronic devices. Full article
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10 pages, 1584 KiB  
Communication
Quantum Mechanical Comparison between Lithiated and Sodiated Silicon Nanowires
by Donald C. Boone
Appl. Nano 2024, 5(2), 48-57; https://doi.org/10.3390/applnano5020005 - 1 Apr 2024
Viewed by 564
Abstract
This computational research study will compare the specific charge capacity (SCC) between lithium ions inserted into crystallized silicon (c-Si) nanowires with that of sodium ions inserted into amorphous silicon (a-Si) nanowires. It will be demonstrated that the potential energy V(r) within a lithium–silicon [...] Read more.
This computational research study will compare the specific charge capacity (SCC) between lithium ions inserted into crystallized silicon (c-Si) nanowires with that of sodium ions inserted into amorphous silicon (a-Si) nanowires. It will be demonstrated that the potential energy V(r) within a lithium–silicon nanowire supports a coherent energy state model with discrete electron particles, while the potential energy of a sodium–silicon nanowire will be discovered to be essentially zero, and, thus, the electron current that travels through a sodiated silicon nanowire will be modeled as a free electron with wave-like characteristics. This is due to the vast differences in the electric fields of lithiated and sodiated silicon nanowires, where the electric fields are of the order of 1010 V/m and 1015 V/m, respectively. The main reason for the great disparity in electric fields is the presence of optical amplification within lithium ions and the absence of this process within sodium ions. It will be shown that optical amplification develops coherent optical interactions, which is the primary reason for the surge of specific charge capacity in the lithiated silicon nanowire. Conversely, the lack of optical amplification is the reason for the incoherent optical interactions within sodium ions, which is the reason for the low presence of SCC in sodiated silicon nanowires. Full article
(This article belongs to the Collection Feature Papers for Applied Nano)
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15 pages, 2590 KiB  
Article
Synthesis and Characterization of B4C-Based Multifunctional Nanoparticles for Boron Neutron Capture Therapy Applications
by Maria Paola Demichelis, Agustina Mariana Portu, Mario Alberto Gadan, Agostina Vitali, Valentina Forlingieri, Silva Bortolussi, Ian Postuma, Andrea Falqui, Elena Vezzoli, Chiara Milanese, Patrizia Sommi and Umberto Anselmi-Tamburini
Appl. Nano 2024, 5(2), 33-47; https://doi.org/10.3390/applnano5020004 - 25 Mar 2024
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Abstract
Nanoparticles composed of inorganic boron-containing compounds represent a promising candidate as 10B carriers for BNCT. This study focuses on the synthesis, characterization, and assessment of the biological activity of composite nanomaterials based on boron carbide (B4C). Boron carbide is a [...] Read more.
Nanoparticles composed of inorganic boron-containing compounds represent a promising candidate as 10B carriers for BNCT. This study focuses on the synthesis, characterization, and assessment of the biological activity of composite nanomaterials based on boron carbide (B4C). Boron carbide is a compelling alternative to borated molecules due to its high volumetric B content, prolonged retention in biological systems, and low toxicity. These attributes lead to a substantial accumulation of B in tissues, eliminating the need for isotopically enriched compounds. In our approach, B4C nanoparticles were included in composite nanostructures with ultrasmall superparamagnetic nanoparticles (SPIONs), coated with poly (acrylic acid), and further functionalized with the fluorophore DiI. The successful internalization of these nanoparticles in HeLa cells was confirmed, and a significant uptake of 10B was observed. Micro-distribution studies were conducted using intracellular neutron autoradiography, providing valuable insights into the spatial distribution of the nanoparticles within cells. These findings strongly indicate that the developed nanomaterials hold significant promise as effective carriers for 10B in BNCT, showcasing their potential for advancing cancer treatment methodologies. Full article
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