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9 pages, 258 KiB

Open AccessEditorial

Synthesis, Physicochemical Characterization and Applications of Advanced Nanomaterials

by Thomas Dippong

Materials 2023, 16(4), 1674; https://doi.org/10.3390/ma16041674 - 17 Feb 2023

Cited by 1 | Viewed by 2035

Abstract

This Special Issue highlights the last decade’s progress regarding new nanostructured materials. In this regard, the development of nanoscale syntheses and innovative characterization tools that resulted in the tailored design of nanostructured materials with versatile abilities in many applications were investigated. Various types [...] Read more.

This Special Issue highlights the last decade’s progress regarding new nanostructured materials. In this regard, the development of nanoscale syntheses and innovative characterization tools that resulted in the tailored design of nanostructured materials with versatile abilities in many applications were investigated. Various types of engineered nanostructures, usually metal nanoparticles or nanoporous metal oxides, have been synthesized for various applications. This Special Issue covers the state-of-the-art of advanced nanoparticles in many disciplines (chemistry, pharmacy, nanomedicine, agriculture, catalysis, and environmental science). The crystallite sizes depended on the annealing temperature and type of doping ion. A combination of rigid and soft particles could simultaneously enhance both the tensile properties and the fracture toughness, which could not be achieved by the single-phase particles independently. The surface charge and in vitro corrosion resistance are key parameters characterizing biomaterials in the interaction of the implant with the biological environment. Solar energy in the presence of a photocatalyst can be effectively converted into electricity/fuel, break down chemical and microbial pollutants, and help water purification. The saturation magnetization, remanent magnetizations, coercivity, and anisotropy were found to depend on the doping ion, annealing temperature, and particle size. The efficiency of the photocatalysis reaction depends on several factors, including light absorption capacity/light intensity, the type of photocatalyst used, the concentration of a photocatalyst and contaminant particles, the pH of the reaction medium, etc. The variety of color pigments and coloring properties of the targeted application in the ceramic industry was also of interest. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

Research

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15 pages, 7293 KiB

Open AccessArticle

In Vitro Bioelectrochemical Properties of Second-Generation Oxide Nanotubes on Ti–13Zr–13Nb Biomedical Alloy

by Agnieszka Stróż, Thomas Luxbacher, Karolina Dudek, Bartosz Chmiela, Patrycja Osak and Bożena Łosiewicz

Materials 2023, 16(4), 1408; https://doi.org/10.3390/ma16041408 - 8 Feb 2023

Cited by 3 | Viewed by 1709

Abstract

Surface charge and in vitro corrosion resistance are some of the key parameters characterizing biomaterials in the interaction of the implant with the biological environment. Hence, this work investigates the in vitro bioelectrochemical behavior of newly developed oxide nanotubes (ONTs) layers of second-generation [...] Read more.

Surface charge and in vitro corrosion resistance are some of the key parameters characterizing biomaterials in the interaction of the implant with the biological environment. Hence, this work investigates the in vitro bioelectrochemical behavior of newly developed oxide nanotubes (ONTs) layers of second-generation (2G) on a Ti–13Zr–13Nb alloy. The 2G ONTs were produced by anodization in 1 M (NH₄)₂SO₄ solution with 2 wt.% of NH₄F. The physical and chemical properties of the obtained bamboo-inspired 2G ONTs were characterized using scanning electron microscopy with field emission and energy dispersive spectroscopy. Zeta potential measurements for the examined materials were carried out using an electrokinetic analyzer in aqueous electrolytes of potassium chloride, phosphate-buffered saline and artificial blood. It was found that the electrolyte type and the ionic strength affect the bioelectrochemical properties of 2G ONTs layers. Open circuit potential and anodic polarization curve results proved the influence of anodizing on the improvement of in vitro corrosion resistance of the Ti–13Zr–13Nb alloy in PBS solution. The anodizing conditions used can be proposed for the production of long-term implants, which are not susceptible to pitting corrosion up to 9.4 V. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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18 pages, 3752 KiB

Open AccessArticle

Extending the Protection Ability and Life Cycle of Medical Masks through the Washing Process

by Julija Volmajer Valh, Tanja Pušić, Mirjana Čurlin and Ana Knežević

Materials 2023, 16(3), 1247; https://doi.org/10.3390/ma16031247 - 1 Feb 2023

Cited by 1 | Viewed by 1803

Abstract

The reuse of decontaminated disposable medical face masks can contribute to reducing the environmental burden of discarded masks. This research is focused on the effect of household and laboratory washing at 50 °C on the quality and functionality of the nonwoven structure of [...] Read more.

The reuse of decontaminated disposable medical face masks can contribute to reducing the environmental burden of discarded masks. This research is focused on the effect of household and laboratory washing at 50 °C on the quality and functionality of the nonwoven structure of polypropylene medical masks by varying the washing procedure, bath composition, disinfectant agent, and number of washing cycles as a basis for reusability. The barrier properties of the medical mask were analyzed before and after the first and fifth washing cycle indirectly by measuring the contact angle of the liquid droplets with the front and back surface of the mask, further by measuring air permeability and determining antimicrobial resistance. Additional analysis included FTIR, pH of the material surface and aqueous extract, as well as the determination of residual substances—surfactants—in the aqueous extract of washed versus unwashed medical masks, while their aesthetic aspect was examined by measuring their spectral characteristics. The results showed that household washing had a stronger impact on the change of some functional properties, primarily air permeability, than laboratory washing. The addition of the disinfectant agent, didecyldimethylammonium chloride, contributes to the protective ability and supports the idea that washing of medical masks under controlled conditions can preserve barrier properties and enable reusability. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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17 pages, 7360 KiB

Open AccessArticle

Influence of Anodizing Conditions on Biotribological and Micromechanical Properties of Ti–13Zr–13Nb Alloy

by Agnieszka Stróż, Joanna Maszybrocka, Tomasz Goryczka, Karolina Dudek, Patrycja Osak and Bożena Łosiewicz

Materials 2023, 16(3), 1237; https://doi.org/10.3390/ma16031237 - 31 Jan 2023

Cited by 4 | Viewed by 1748

Abstract

The biomedical Ti–13Zr–13Nb bi-phase (α + β) alloy for long-term applications in implantology has recently been developed. The porous oxide nanotubes’ (ONTs) layers of various geometries and lengths on the Ti–13Zr–13Nb alloy surface can be produced by anodizing to improve osseointegration. This work [...] Read more.

The biomedical Ti–13Zr–13Nb bi-phase (α + β) alloy for long-term applications in implantology has recently been developed. The porous oxide nanotubes’ (ONTs) layers of various geometries and lengths on the Ti–13Zr–13Nb alloy surface can be produced by anodizing to improve osseointegration. This work was aimed at how anodizing conditions determinatine the micromechanical and biotribological properties of the Ti–13Zr–13Nb alloy. First-generation (1G), second-generation (2G), and third-generation (3G) ONT layers were produced on the Ti–13Zr–13Nb alloy surface by anodizing. The microstructure was characterized using SEM. Micromechanical properties were investigated by the Vickers microhardness test under variable loads. Biotribological properties were examined in Ringer’s solution in a reciprocating motion in the ball-on-flat system. The 2D roughness profiles method was used to assess the wear tracks of the tested materials. Wear scars’ analysis of the ZrO₂ ball was performed using optical microscopy. It was found that the composition of the electrolyte with the presence of fluoride ions was an essential factor influencing the micromechanical and biotribological properties of the obtained ONT layers. The three-body abrasion wear mechanism was proposed to explain the biotribological wear in Ringer’s solution for the Ti–13Zr–13Nb alloy before and after anodizing. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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16 pages, 2963 KiB

Open AccessFeature PaperArticle

Modification of Some Structural and Functional Parameters of Living Culture of Arthrospira platensis as the Result of Selenium Nanoparticle Biosynthesis

by Liliana Cepoi, Inga Zinicovscaia, Tatiana Chiriac, Ludmila Rudi, Nikita Yushin, Dmitrii Grozdov, Ion Tasca, Elena Kravchenko and Kirill Tarasov

Materials 2023, 16(2), 852; https://doi.org/10.3390/ma16020852 - 15 Jan 2023

Cited by 4 | Viewed by 1686

Abstract

Selenium nanoparticles are attracting the attention of researchers due to their multiple applications, including medicine. The biosynthesis of selenium nanoparticles has become particularly important due to the environmentally friendly character of the process and special properties of the obtained particles. The possibility of [...] Read more.

Selenium nanoparticles are attracting the attention of researchers due to their multiple applications, including medicine. The biosynthesis of selenium nanoparticles has become particularly important due to the environmentally friendly character of the process and special properties of the obtained particles. The possibility of performing the biosynthesis of selenium nanoparticles via the living culture of Arthrospira platensis starting from sodium selenite was studied. The bioaccumulation capacity of the culture, along with changes in the main biochemical parameters of the biomass, the ultrastructural changes in the cells during biosynthesis and the change in the expression of some genes involved in stress response reactions were determined. Protein, lipid and polysaccharide fractions were obtained from the biomass grown in the presence of sodium selenite. The formation of selenium nanoparticles in the protein fraction was demonstrated. Thus, Arthrospira platensis culture can be considered a suitable matrix for the biosynthesis of selenium nanoparticles. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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12 pages, 3006 KiB

Open AccessEditor’s ChoiceArticle

One-Step Synthesis of Sulfur-Doped Nanoporous Carbons from Lignin with Ultra-High Surface Area, Sulfur Content and CO₂ Adsorption Capacity

by Dipendu Saha, Gerassimos Orkoulas and Dean Bates

Materials 2023, 16(1), 455; https://doi.org/10.3390/ma16010455 - 3 Jan 2023

Cited by 6 | Viewed by 2379

Abstract

Lignin is the second-most available biopolymer in nature. In this work, lignin was employed as the carbon precursor for the one-step synthesis of sulfur-doped nanoporous carbons. Sulfur-doped nanoporous carbons have several applications in scientific and technological sectors. In order to synthesize sulfur-doped nanoporous [...] Read more.

Lignin is the second-most available biopolymer in nature. In this work, lignin was employed as the carbon precursor for the one-step synthesis of sulfur-doped nanoporous carbons. Sulfur-doped nanoporous carbons have several applications in scientific and technological sectors. In order to synthesize sulfur-doped nanoporous carbons from lignin, sodium thiosulfate was employed as a sulfurizing agent and potassium hydroxide as the activating agent to create porosity. The resultant carbons were characterized by pore textural properties, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The nanoporous carbons possess BET surface areas of 741–3626 m²/g and a total pore volume of 0.5–1.74 cm³/g. The BET surface area of the carbon was one of the highest that was reported for any carbon-based materials. The sulfur contents of the carbons are 1–12.6 at.%, and the key functionalities include S=C, S-C=O, and SO_x. The adsorption isotherms of three gases, CO₂, CH₄, and N₂, were measured at 298 K, with pressure up to 1 bar. In all the carbons, the adsorbed amount was highest for CO₂, followed by CH₄ and N₂. The equilibrium uptake capacity for CO₂ was as high as ~11 mmol/g at 298 K and 760 torr, which is likely the highest among all the porous carbon-based materials reported so far. Ideally adsorbed solution theory (IAST) was employed to calculate the selectivity for CO₂/N₂, CO₂/CH₄, and CH₄/N₂, and some of the carbons reported a very high selectivity value. The overall results suggest that these carbons can potentially be used for gas separation purposes. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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13 pages, 3041 KiB

Open AccessFeature PaperArticle

The New Reliable pH Sensor Based on Hydrous Iridium Dioxide and Its Composites

by Nikola Lenar, Robert Piech and Beata Paczosa-Bator

Materials 2023, 16(1), 192; https://doi.org/10.3390/ma16010192 - 25 Dec 2022

Cited by 5 | Viewed by 1801

Abstract

The new reliable sensor for pH determination was designed with the use of hydrous iridium dioxide and its composites. Three different hIrO₂-based materials were prepared and applied as solid-contact layers in pH-selective electrodes with polymeric membrane. The material choice included standalone [...] Read more.

The new reliable sensor for pH determination was designed with the use of hydrous iridium dioxide and its composites. Three different hIrO₂-based materials were prepared and applied as solid-contact layers in pH-selective electrodes with polymeric membrane. The material choice included standalone hydrous iridium oxide; composite material of hydrous iridium oxide, carbon nanotubes, and triple composite material composed of hydrous iridium oxide; carbon nanotubes; and poly(3-octylthiophene-2,5-diyl). The paper depicts that the addition of functional material to standalone metal oxide is beneficial for the performance of solid-state ion-selective electrodes and presents the universal approach to designing this type of sensors. Each component contributed differently to the sensors’ performance—the addition of carbon nanotubes increased the electrical capacitance of sensor (up to 400 µF) while the addition of conducting polymer allowed it to increase the contact angle of material changing its wetting properties and enhancing the stability of potentiometric response. Hydrous iridium oxide contacted electrodes exhibit linear response in wide linear range of pH (2–11) and stable potentiometric response (the lowest potential drift of 0.036 mV/h is attributed to the electrode with triple composite material). Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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13 pages, 7436 KiB

Open AccessArticle

Modification of Electrospun CeO₂ Nanofibers with CuCrO₂ Particles Applied to Hydrogen Harvest from Steam Reforming of Methanol

by Kai-Chun Hsu, Chung-Lun Yu, Heng-Jyun Lei, Subramanian Sakthinathan, Po-Chou Chen, Chia-Cheng Lin, Te-Wei Chiu, Karuppiah Nagaraj, Liangdong Fan and Yi-Hsuan Lee

Materials 2022, 15(24), 8770; https://doi.org/10.3390/ma15248770 - 8 Dec 2022

Cited by 4 | Viewed by 1958

Abstract

Hydrogen is the alternative renewable energy source for addressing the energy crisis, global warming, and climate change. Hydrogen is mostly obtained in the industrial process by steam reforming of natural gas. In the present work, CuCrO₂ particles were attached to the surfaces [...] Read more.

Hydrogen is the alternative renewable energy source for addressing the energy crisis, global warming, and climate change. Hydrogen is mostly obtained in the industrial process by steam reforming of natural gas. In the present work, CuCrO₂ particles were attached to the surfaces of electrospun CeO₂ nanofibers to form CeO₂-CuCrO₂ nanofibers. However, the CuCrO₂ particles did not readily adhere to the surfaces of the CeO₂ nanofibers, so a trace amount of SiO₂ was added to the surfaces to make them hydrophilic. After the SiO₂ modification, the CeO₂ nanofibers were immersed in Cu-Cr-O precursor and annealed in a vacuum atmosphere to form CeO₂-CuCrO₂ nanofibers. The CuCrO₂, CeO₂, and CeO₂-CuCrO₂ nanofibers were examined by X-ray diffraction analysis, transmission electron microscopy, field emission scanning electron microscopy, scanning transmission electron microscope, thermogravimetric analysis, and Brunauer–Emmett–Teller studies (BET). The BET surface area of the CeO₂-CuCrO₂ nanofibers was 15.06 m²/g. The CeO₂-CuCrO₂ nanofibers exhibited hydrogen generation rates of up to 1335.16 mL min⁻¹ g-cat⁻¹ at 773 K. Furthermore, the CeO₂-CuCrO₂ nanofibers produced more hydrogen at lower temperatures. The hydrogen generation performance of these CeO₂-CuCrO₂ nanofibers could be of great importance in industry and have an economic impact. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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15 pages, 5171 KiB

Open AccessArticle

The Effect of Ni²⁺ Ions Substitution on Structural, Morphological, and Optical Properties in CoCr₂O₄ Matrix as Pigments in Ceramic Glazes

by Firuta Goga, Rares Adrian Bortnic, Alexandra Avram, Mioara Zagrai, Lucian Barbu Tudoran and Raluca Anca Mereu

Materials 2022, 15(24), 8713; https://doi.org/10.3390/ma15248713 - 7 Dec 2022

Cited by 6 | Viewed by 1859

Abstract

The structural, morphological, and optical properties of Ni²⁺ ions substitution in CoCr₂O₄ matrix as ceramic pigments were investigated. The thermal decomposition of the dried gel was performed aiming to understand the mass changes during annealing. The X-ray diffraction (XRD) [...] Read more.

The structural, morphological, and optical properties of Ni²⁺ ions substitution in CoCr₂O₄ matrix as ceramic pigments were investigated. The thermal decomposition of the dried gel was performed aiming to understand the mass changes during annealing. The X-ray diffraction (XRD) studies reveal a spinel-type Face–Centered Cubic structure and a secondary Cr₂O₃ phase when x ≤ 0.75 and a Body–Centered Tetragonal structure when x = 1. Fourier Transform Infrared Spectroscopy (FT–IR) indicated two strong absorption bands corresponding to the metal–oxygen stretching from tetrahedral and octahedral sites, characteristic of spinel structure. Ultraviolet–Visible (UV–Vis) spectra exhibited the electronic transitions of the Cr²⁺ Cr³⁺ and Ni²⁺ ions. From the UV–Vis data, the CIE color coordinates, (x, y) of the pigments were evaluated. The morphology was examined by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) showing the agglomeration behavior of the particles. The stability, coloring properties and potential ceramic applications of studied pigments were tested by their incorporation in matte and glossy tile glazes followed by the application of obtained glazes on ceramic tiles. This study highlights the change in pigment color (from turquoise to a yellowish green) with Ni²⁺ ions substitution in the CoCr₂O₄ spinel matrix. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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14 pages, 9211 KiB

Open AccessArticle

WO₃ Nanopores Array Modified by Au Trisoctahedral NPs: Formation, Characterization and SERS Application

by Jan Krajczewski, Robert Ambroziak, Sylwia Turczyniak-Surdacka and Małgorzata Dziubałtowska

Materials 2022, 15(23), 8706; https://doi.org/10.3390/ma15238706 - 6 Dec 2022

Cited by 3 | Viewed by 1832

Abstract

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 [...] Read more.

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 WO_x 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. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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9 pages, 3341 KiB

Open AccessArticle

Magnetocaloric and Giant Magnetoresistance Effects in La-Ba-Mn-Ti-O Epitaxial Thin Films: Influence of Phase Transition and Magnetic Anisotropy

by Marwène Oumezzine, Cristina Florentina Chirila, Iuliana Pasuk, Aurelian Catalin Galca, Aurel Leca, Bogdana Borca and Victor Kuncser

Materials 2022, 15(22), 8003; https://doi.org/10.3390/ma15228003 - 12 Nov 2022

Cited by 3 | Viewed by 1565

Abstract

Magnetic perovskite films have promising properties for use in energy-efficient spintronic devices and magnetic refrigeration. Here, an epitaxial ferromagnetic La_0.67Ba_0.33Mn_0.95Ti_0.05O₃ (LBMTO-5) thin film was grown on SrTiO₃(001) single crystal substrate by pulsed [...] Read more.

Magnetic perovskite films have promising properties for use in energy-efficient spintronic devices and magnetic refrigeration. Here, an epitaxial ferromagnetic La_0.67Ba_0.33Mn_0.95Ti_0.05O₃ (LBMTO-5) thin film was grown on SrTiO₃(001) single crystal substrate by pulsed laser deposition. High-resolution X-ray diffraction proved the high crystallinity of the film with tetragonal symmetry. The magnetic, magnetocaloric and magnetoresistance properties at different directions of the applied magnetic field with respect to the ab plane of the film were investigated. An in-plane uni-axial magnetic anisotropy was evidenced. The LBMTO-5 epilayer exhibits a second-order ferromagnetic-paramagnetic phase transition around 234 K together with a metal–semiconductor transition close to this Curie temperature (T_C). The magnetic entropy variation under 5 T induction of a magnetic field applied parallel to the film surface reaches a maximum of 17.27 mJ/cm³ K. The relative cooling power is 1400 mJ/cm³ K (53% of the reference value reported for bulk Gd) for the same applied magnetic field. Giant magnetoresistance of about 82% under 5 T is obtained at a temperature close to T_C. Defined as the difference between specific resistivity obtained under 5 T with the current flowing along the magnetic easy axis and the magnetic field oriented transversally to the current, parallel and perpendicular to the sample plane, respectively, the in-plane magneto-resistance anisotropy in 5 T is about 9% near the T_C. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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11 pages, 1856 KiB

Open AccessArticle

A Novel Dual-Emission Fluorescence Probe Based on CDs and Eu³⁺ Functionalized UiO-66-(COOH)₂ Hybrid for Visual Monitoring of Cu²⁺

by Jie Che, Xin Jiang, Yangchun Fan, Mingfeng Li, Xuejuan Zhang, Daojiang Gao, Zhanglei Ning and Hongda Li

Materials 2022, 15(22), 7933; https://doi.org/10.3390/ma15227933 - 10 Nov 2022

Cited by 4 | Viewed by 1967

Abstract

In this work, CDs@Eu-UiO-66(COOH)₂ (denoted as CDs-F2), a fluorescent material made up of carbon dots (CDs) and a Eu³⁺ functionalized metal–organic framework, has been designed and prepared via a post-synthetic modification method. The synthesized CDs-F2 presents dual emissions at 410 nm [...] Read more.

In this work, CDs@Eu-UiO-66(COOH)₂ (denoted as CDs-F2), a fluorescent material made up of carbon dots (CDs) and a Eu³⁺ functionalized metal–organic framework, has been designed and prepared via a post-synthetic modification method. The synthesized CDs-F2 presents dual emissions at 410 nm and 615 nm, which can effectively avoid environmental interference. CDs-F2 exhibits outstanding selectivity, great sensitivity, and good anti-interference for ratiometric sensing Cu²⁺ in water. The linear range is 0–200 µM and the limit of detection is 0.409 µM. Interestingly, the CDs-F2’s silicon plate achieves rapid and selective detection of Cu²⁺. The change in fluorescence color can be observed by the naked eye. These results reveal that the CDs-F2 hybrid can be employed as a simple, rapid, and sensitive fluorescent probe to detect Cu²⁺. Moreover, the possible sensing mechanism of this dual-emission fluorescent probe is discussed in detail. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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15 pages, 2642 KiB

Open AccessArticle

Mechanical Properties of Orthodontic Cements and Their Behavior in Acidic Environments

by Cristina Iosif, Stanca Cuc, Doina Prodan, Marioara Moldovan, Ioan Petean, Anca Labunet, Lucian Barbu Tudoran, Iulia Clara Badea, Sorin Claudiu Man, Mîndra Eugenia Badea and Radu Chifor

Materials 2022, 15(22), 7904; https://doi.org/10.3390/ma15227904 - 9 Nov 2022

Cited by 4 | Viewed by 1664

Abstract

The present research is focused on three different classes of orthodontic cements: resin composites (e.g., BracePaste); resin-modified glass ionomer RMGIC (e.g., Fuji Ortho) and resin cement (e.g., Transbond). Their mechanical properties such as compressive strength, diametral tensile strength and flexural strength were correlated [...] Read more.

The present research is focused on three different classes of orthodontic cements: resin composites (e.g., BracePaste); resin-modified glass ionomer RMGIC (e.g., Fuji Ortho) and resin cement (e.g., Transbond). Their mechanical properties such as compressive strength, diametral tensile strength and flexural strength were correlated with the samples’ microstructures, liquid absorption, and solubility in liquid. The results show that the best compressive (100 MPa) and flexural strength (75 Mpa) was obtained by BracePaste and the best diametral tensile strength was obtained by Transbond (230 MPa). The lowestvalues were obtained by Fuji Ortho RMGIC. The elastic modulus is relatively high around 14 GPa for BracePaste, and Fuji Ortho and Transbond have only 7 GPa. The samples were also subjected to artificial saliva and tested in different acidic environments such as Coca-Cola and Red Bull. Their absorption and solubility were investigated at different times ranging from 1 day to 21 days. Fuji Ortho presents the highest liquid absorption followed by Transbond, the artificial saliva has the best absorption and Red Bull has the lowest absorption. The best resistance to the liquids was obtained by BracePaste in all environments. Coca-Cola presents values four times greater than the ones observed for artificial saliva. Solubility tests show that BracePaste is more soluble in artificial saliva, and Fuji Ortho and Transbond are more soluble in Red Bull and Coca-Cola. Scanning electron microscopy (SEM) images evidenced a compact structure for BracePaste in all environments sustaining the lower liquid absorption values. Fuji Ortho and Transbond present a fissure network allowing the liquid to carry out in-depth penetration of materials. SEM observations are in good agreement with the atomic force microscopy (AFM) results. The surface roughness decreases with the acidity increasing for BracePaste meanwhile it increases with the acidity for Fuji Ortho and Transbond. In conclusion: BracePaste is recommended for long-term orthodontic treatment for patients who regularly consume acidic beverages, Fuji Ortho is recommended for short-term orthodontic treatment for patients who regularly consume acidic beverages and Transbond is recommended for orthodontic treatment over an average time period for patients who do not regularly consume acidic beverages. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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16 pages, 4273 KiB

Open AccessArticle

Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Manganites La_(0.7−x)Eu_xBa_0.3MnO₃

by Roman Atanasov, Rares Bortnic, Razvan Hirian, Eniko Covaci, Tiberiu Frentiu, Florin Popa and Iosif Grigore Deac

Materials 2022, 15(21), 7645; https://doi.org/10.3390/ma15217645 - 31 Oct 2022

Cited by 11 | Viewed by 1728

Abstract

Here, we report synthesis and investigations of bulk and nano-sized La_(0.7−x)Eu_xBa_0.3MnO₃ (x ≤ 0.4) compounds. The study presents a comparison between the structural and magnetic properties of the nano- and polycrystalline manganites La_(0.7−x)Eu_x [...] Read more.

Here, we report synthesis and investigations of bulk and nano-sized La_(0.7−x)Eu_xBa_0.3MnO₃ (x ≤ 0.4) compounds. The study presents a comparison between the structural and magnetic properties of the nano- and polycrystalline manganites La_(0.7−x)Eu_xBa_0.3MnO₃, which are potential magnetocaloric materials to be used in domestic magnetic refrigeration close to room temperature. The parent compound, La_0.7Ba_0.3MnO₃, has Curie temperature T_C = 340 K. The magnetocaloric effect is at its maximum around T_C. To reduce this temperature below 300 K, we partially replaced the La ions with Eu ions. A solid-state reaction was used to prepare bulk polycrystalline materials, and a sol-gel method was used for the nanoparticles. X-ray diffraction was used for the structural characterization of the compounds. Transmission electron spectroscopy (TEM) evidenced nanoparticle sizes in the range of 40–80 nm. Iodometry and inductively coupled plasma optical emission spectrometry (ICP-OES) was used to investigate the oxygen content of the studied compounds. Critical exponents were calculated for all samples, with bulk samples being governed by tricritical mean field model and nanocrystalline samples governed by the 3D Heisenberg model. The bulk sample with x = 0.05 shows room temperature phase transition T_C = 297 K, which decreases with increasing x for the other samples. All nano-sized compounds show lower T_C values compared to the same bulk samples. The magnetocaloric effect in bulk samples revealed a greater magnetic entropy change in a relatively narrow temperature range, while nanoparticles show lower values, but in a temperature range several times larger. The relative cooling power for bulk and nano-sized samples exhibit approximately equal values for the same substitution level, and this fact can substantially contribute to applications in magnetic refrigeration near room temperature. By combining the magnetic properties of the nano- and polycrystalline manganites, better magnetocaloric materials can be obtained. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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15 pages, 4704 KiB

Open AccessArticle

Silver Depreciation in 3-Polker Coins Issued during 1619–1627 by Sigismund III Vasa King of Poland

by Ioan Petean, Gertrud Alexandra Paltinean, Emanoil Pripon, Gheorghe Borodi and Lucian Barbu Tudoran

Materials 2022, 15(21), 7514; https://doi.org/10.3390/ma15217514 - 26 Oct 2022

Cited by 5 | Viewed by 1973

Abstract

The present research is focused on the 3-Polker coins issued during 1619–1627 by Sigismund III Vasa, King of Poland. A major financial crisis took place at that time due to the 30-year War, which started in 1619. There are two theories among historians [...] Read more.

The present research is focused on the 3-Polker coins issued during 1619–1627 by Sigismund III Vasa, King of Poland. A major financial crisis took place at that time due to the 30-year War, which started in 1619. There are two theories among historians concerning the silver depreciation of these coins. The most common theory (generally accepted without proof) is that the later years of issue are depreciated below 60% Ag. The second theory is based on the medieval sources that indicate inflation during the years from 1621–1625, but the medieval source only refers to the inflation of the type of coins and does not mention the issuer. Therefore, in this study, we use modern investigation techniques and materials science methods to help historians elucidate the aforementioned aspects regarding the medieval period. The XRD investigation results are in good agreement with the SEM-EDX elemental analysis. The coins from 1619 and 1620 have high silver content, namely, 86.97% and 92.49%, which corresponds to good silver. The amount of Ag found in the coins from 1621–1625 issituated in the range of 63.2–74.6%. The silver titleis suddenly restored in 1626 at about 84.3% and is kept in a good range until the end of this decree under Sigismund III in 1627. In conclusion, the second theory was partly validated by our experimental results, certifying the currency depreciation during 1621–1625, but the silver title was not lower than 54.2%. Notably, even this depreciated silver title assures a good quality of the 3-Polker coins compared to similar coins issued in other countries that were copper–silver-plated. Therefore, the 3-Polker coins were preferably hoarded at that time.Small alterations in the mint mark’s design were observed in all the depreciated coins compared to the good ones. This might be a sign for an expert to identify the depreciated coins, a fact which requires supplementary investigations. The silver title’s restoration in 1626 also came with a complete change of the mintmark. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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15 pages, 3178 KiB

Open AccessArticle

Effect of Core–Shell Rubber Nanoparticles on the Mechanical Properties of Epoxy and Epoxy-Based CFRP

by Tatjana Glaskova-Kuzmina, Leons Stankevics, Sergejs Tarasovs, Jevgenijs Sevcenko, Vladimir Špaček, Anatolijs Sarakovskis, Aleksejs Zolotarjovs, Krishjanis Shmits and Andrey Aniskevich

Materials 2022, 15(21), 7502; https://doi.org/10.3390/ma15217502 - 26 Oct 2022

Cited by 10 | Viewed by 1916

Abstract

The aim of the research was to estimate the effect of core–shell rubber (CSR) nanoparticles on the tensile properties, fracture toughness, and glass transition temperature of the epoxy and epoxy-based carbon fiber reinforced polymer (CFRP). Three additives containing CSR nanoparticles were used for [...] Read more.

The aim of the research was to estimate the effect of core–shell rubber (CSR) nanoparticles on the tensile properties, fracture toughness, and glass transition temperature of the epoxy and epoxy-based carbon fiber reinforced polymer (CFRP). Three additives containing CSR nanoparticles were used for the research resulting in a filler fraction of 2–6 wt.% in the epoxy resin. It was experimentally confirmed that the effect of the CSR nanoparticles on the tensile properties of the epoxy resin was notable, leading to a reduction of 10–20% in the tensile strength and elastic modulus and an increase of 60–108% in the fracture toughness for the highest filler fraction. The interlaminar fracture toughness of CFRP was maximally improved by 53% for ACE MX 960 at CSR content 4 wt.%. The glass transition temperature of the epoxy was gradually improved by 10–20 °C with the increase of CSR nanoparticles for all of the additives. A combination of rigid and soft particles could simultaneously enhance both the tensile properties and the fracture toughness, which cannot be achieved by the single-phase particles independently. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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16 pages, 4026 KiB

Open AccessArticle

Structural Aspects and Intermolecular Energy for Some Short Testosterone Esters

by Alexandru Turza, Violeta Popescu, Liviu Mare and Gheorghe Borodi

Materials 2022, 15(20), 7245; https://doi.org/10.3390/ma15207245 - 17 Oct 2022

Cited by 7 | Viewed by 2267

Abstract

Testosterone (17β-hydroxyandrost-4-en-3-one) is the primary naturally occurring anabolic–androgenic steroid. The crystal structures of three short esterified forms of testosterone, including propionate, phenylpropionate, and isocaproate ester, were determined via single-crystal X-ray diffraction. Furthermore, all the samples were investigated using powder X-ray diffraction, and their [...] Read more.

Testosterone (17β-hydroxyandrost-4-en-3-one) is the primary naturally occurring anabolic–androgenic steroid. The crystal structures of three short esterified forms of testosterone, including propionate, phenylpropionate, and isocaproate ester, were determined via single-crystal X-ray diffraction. Furthermore, all the samples were investigated using powder X-ray diffraction, and their structural features were described and evaluated in terms of crystal energies and Hirshfeld surfaces. They were also compared with the base form of testosterone (without ester) and the acetate ester. Moreover, from a pharmaceutical perspective, their solubility was evaluated and correlated with the length of the ester. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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14 pages, 6381 KiB

Open AccessArticle

Effect of Transition Metal Doping on the Structural, Morphological, and Magnetic Properties of NiFe₂O₄

by Thomas Dippong, Oana Cadar and Erika Andrea Levei

Materials 2022, 15(9), 2996; https://doi.org/10.3390/ma15092996 - 20 Apr 2022

Cited by 22 | Viewed by 2720

Abstract

Sol-gel route followed by thermal treatment was used to produce NiFe₂O₄ doped with transition metal ions (Zn²⁺, Mn²⁺, Co²⁺). The structural, morphological, and magnetic properties of the doped NiFe₂O₄ were compared [...] Read more.

Sol-gel route followed by thermal treatment was used to produce NiFe₂O₄ doped with transition metal ions (Zn²⁺, Mn²⁺, Co²⁺). The structural, morphological, and magnetic properties of the doped NiFe₂O₄ were compared with those of virgin NiFe₂O₄. The metal-glyoxylates’ formation and decomposition as well as the thermal stability of the doped and virgin ferrites were assessed by thermal analysis. The functional groups identified by Fourier-transform infrared spectroscopy confirmed the decomposition of metal nitrates, the formation and decomposition of precursors, and the formation of the SiO₂ matrix. The X-ray diffraction indicated that the sol-gel synthesis produced single-phase crystalline ferrites in case of virgin, Zn²⁺ and Co²⁺-doped Ni-ferrites. By doping with Mn²⁺, several secondary phases derived from the SiO₂ matrix accompanied the crystalline spinel ferrite. The crystallite sizes depended on the annealing temperature and type of doping ion. The gradual increase of lattice parameters suggested the uniform distribution of doping metal ions in the NiFe₂O₄ lattice. The saturation magnetization, remanent magnetizations, coercivity, and anisotropy were found to depend on the doping ion, annealing temperature, and particle size. The high saturation magnetization values of the obtained nanocomposites make them suitable for a wide range of applications in the field of sensors development and construction. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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Review

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22 pages, 1423 KiB

Open AccessReview

Nanomaterials as Photocatalysts—Synthesis and Their Potential Applications

by Agnieszka Feliczak-Guzik

Materials 2023, 16(1), 193; https://doi.org/10.3390/ma16010193 - 25 Dec 2022

Cited by 20 | Viewed by 4029

Abstract

Increasing demand for energy and environmental degradation are the most serious problems facing the man. An interesting issue that can contribute to solving these problems is the use of photocatalysis. According to literature, solar energy in the presence of a photocatalyst can effectively [...] Read more.

Increasing demand for energy and environmental degradation are the most serious problems facing the man. An interesting issue that can contribute to solving these problems is the use of photocatalysis. According to literature, solar energy in the presence of a photocatalyst can effectively (i) be converted into electricity/fuel, (ii) break down chemical and microbial pollutants, and (iii) help water purification. Therefore, the search for new, efficient, and stable photocatalysts with high application potential is a point of great interest. The photocatalysts must be characterized by the ability to absorb radiation from a wide spectral range of light, the appropriate position of the semiconductor energy bands in relation to the redox reaction potentials, and the long diffusion path of charge carriers, besides the thermodynamic, electrochemical, and photoelectrochemical stabilities. Meeting these requirements by semiconductors is very difficult. Therefore, efforts are being made to increase the efficiency of photo processes by changing the electron structure, surface morphology, and crystal structure of semiconductors. This paper reviews the recent literature covering the synthesis and application of nanomaterials in photocatalysis. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Sustainable Advanced Nanomaterials)

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