Nanomaterials

16 pages, 746 KiB

Open AccessArticle

Calibrations, Validations, and Checks of a Dual 23 nm and 10 nm Diffusion Charger-Based Portable Emissions Measurement System (PEMS)

by Anastasios Melas, Maria Trikka, Sara Valentini, Giulio Cotogno and Barouch Giechaskiel

Nanomaterials 2024, 14(15), 1258; https://doi.org/10.3390/nano14151258 (registering DOI) - 27 Jul 2024

Abstract

The upcoming Euro 7 vehicle exhaust emissions regulation includes particle number (PN) limits for all vehicles, not only those with direct fuel injection. It also sets the lower detection particle size of the PN methodology to 10 nm from 23 nm. Recently, a [...] Read more.

The upcoming Euro 7 vehicle exhaust emissions regulation includes particle number (PN) limits for all vehicles, not only those with direct fuel injection. It also sets the lower detection particle size of the PN methodology to 10 nm from 23 nm. Recently, a commercial diffusion charger-based PEMS added the possibility of switching the lower size between 23 nm and 10 nm. In this study, we assessed the dual PEMS in the calibration laboratory using diffusion flame soot or spark discharge graphite particles following the regulated procedures. Furthermore, we compared the dual PEMS with a laboratory grade system (LABS) using soot, graphite, and vehicle exhaust particles. To put the results into perspective, we added comparisons (validations) of two additional 23 nm PEMSs with LABSs over a three-year period. The results showed that the differences of the 23 nm PEMSs remained the same (around 35% underestimation) over the years and were similar to the dual PEMS. This difference is still well within the permissible tolerance from the regulation (50%). We argued that the reason is the calibration material used by the manufacturer (spark discharge graphite). We demonstrated that calibrating with combustion soot could reduce the differences. The 10 nm PEMS gave similar results but with much smaller differences, indicating that the calibration material is of less importance for the Euro 7 step. The results showed that the measurement uncertainty has not increased but rather decreased for the specific PEMS switching from 23 nm to 10 nm. Full article

11 pages, 2015 KiB

Open AccessArticle

Engineering of LiTaO₃ Nanoparticles by Flame Spray Pyrolysis: Understanding In Situ Li-Incorporation into the Ta₂O₅ Lattice

by Pavlos Psathas, Areti Zindrou, Anastasia V. Spyrou and Yiannis Deligiannakis

Nanomaterials 2024, 14(15), 1257; https://doi.org/10.3390/nano14151257 (registering DOI) - 27 Jul 2024

Abstract

Lithium tantalate (LiTaO₃) perovskite finds wide use in pyroelectric detectors, optical waveguides and piezoelectric transducers, stemming from its good mechanical and chemical stability and optical transparency. Herein, we present a method for synthesis of LiTaO₃ nanoparticles using a scalable Flame [...] Read more.

Lithium tantalate (LiTaO₃) perovskite finds wide use in pyroelectric detectors, optical waveguides and piezoelectric transducers, stemming from its good mechanical and chemical stability and optical transparency. Herein, we present a method for synthesis of LiTaO₃ nanoparticles using a scalable Flame Spray Pyrolysis (FSP) technology, that allows the formation of LiTaO₃ nanomaterials in a single step. Raman, XRD and TEM studies allow for comprehension of the formation mechanism of the LiTaO₃ nanophases, with particular emphasis on the penetration of Li atoms into the Ta-oxide lattice. We show that, control of the High-Temperature Particle Residence Time (HTPRT) in the FSP flame, is the key-parameter that allows successful penetration of the -otherwise amorphous- Li phase into the Ta₂O₅ nanophase. In this way, via control of the HTPRT in the FSP process, we synthesized a series of nanostructured LiTaO₃ particles of varying phase composition from {amorphous Li/Ta₂O₅/LiTaO₃} to {pure LiTaO₃, 15–25 nm}. Finally, the photophysical activity of the FSP-made LiTaO₃ was validated for photocatalytic H₂ production from H₂O. These data are discussed in conjunction with the role of the phase composition of the LiTaO₃ nanoparticles. More generally, the present work allows a better understanding of the mechanism of ABO₃ perovskite formation that requires the incorporation of two cations, A and B, into the nanolattice. Full article

(This article belongs to the Section Energy and Catalysis)

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11 pages, 4101 KiB

Open AccessArticle

Polarized Raman Study of First-Order Phonons in Self-Flux Grown Single-Crystalline WTe₂

by Peter M. Rafailov, Dimitre Dimitrov, Daniela Kovacheva and Vera Marinova

Nanomaterials 2024, 14(15), 1256; https://doi.org/10.3390/nano14151256 (registering DOI) - 27 Jul 2024

Abstract

Bulk single crystals of WTe₂ were grown by the self-flux method and characterized by X-ray diffraction, polarized micro-Raman spectroscopy, and optical microscopy. All methods revealed a high crystalline quality, thus demonstrating the advantages of the growth method used as a starting base [...] Read more.

Bulk single crystals of WTe₂ were grown by the self-flux method and characterized by X-ray diffraction, polarized micro-Raman spectroscopy, and optical microscopy. All methods revealed a high crystalline quality, thus demonstrating the advantages of the growth method used as a starting base for the synthesis of high-quality 2D materials. In each main scattering configuration, we recorded a series of Raman spectra in different sample orientations achieved by rotating the sample around the incident laser beam. In addition to the well-established case of excitation along the c crystal axis, we also applied laser excitation along the a and b axes. Thus, scattering configurations were also realized in the XZ and YZ polarization planes, for which no comparative literature data have yet been established. In these experiments, two new Raman-active phonons with B₂ symmetry and frequencies of 89 cm⁻¹ and 122 cm⁻¹ were identified. The obtained experimental data enabled us to derive the magnitude ratios of all three tensor elements of the A₁ modes and to find their phase differences. Full article

(This article belongs to the Section 2D and Carbon Nanomaterials)

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14 pages, 6240 KiB

Open AccessArticle

Multi-Stimuli-Responsive Fluorescent Molecule with AIE and TICT Properties Based on 1,8-Naphthalimide

by Yan Yu, Na Qiang, Zhu Liu, Ming Lu, Yuqiu Shen, Jiao Zou, Jinyu Yang and Guocong Liu

Nanomaterials 2024, 14(15), 1255; https://doi.org/10.3390/nano14151255 (registering DOI) - 27 Jul 2024

Abstract

A multi-stimuli responsive fluorophore, named NBDNI, was developed by constructing a 1,8-naphthalimide derivative in which a rotatable electron-donating N,N-dimethylaniline group attached to its 4-position. This molecular structure endowed NBDNI with aggregate-induced emission (AIE) and twisted intramolecular charge transfer (TICT) properties, enabling remarkable fluorescence [...] Read more.

A multi-stimuli responsive fluorophore, named NBDNI, was developed by constructing a 1,8-naphthalimide derivative in which a rotatable electron-donating N,N-dimethylaniline group attached to its 4-position. This molecular structure endowed NBDNI with aggregate-induced emission (AIE) and twisted intramolecular charge transfer (TICT) properties, enabling remarkable fluorescence changes in response to multiple external stimuli: (i) sensitivity to polarity in various solvent systems and polymer matrix; (ii) significant fluorescence response and excellent linearity towards temperature changes in solution; (iii) distinct switch of fluorescence color upon acid and base treatments; (iv) reversible mechanochromism behavior in the solid state. Moreover, the mechanisms underlying the aforementioned stimuli-responsive phenomena have been proposed based on comprehensive systematic measurements. Furthermore, preliminary applications such as fluorescence thermometry and acid/base test paper have been demonstrated. This research will bring about new opportunities for the development of novel stimuli-responsive luminescent materials. Full article

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18 pages, 2495 KiB

Open AccessArticle

Ultrasonication-Assisted Green Synthesis and Physicochemical and Cytotoxic Activity Characterization of Protein-Based Nanoparticles from Moringa oleifera Seeds

by Amany Abd El-Shafy Abd El-Kader Nafeh, Ibrahim Mohamed Abd El-Aleem Mohamed and Mohamed Frahat Foda

Nanomaterials 2024, 14(15), 1254; https://doi.org/10.3390/nano14151254 - 26 Jul 2024

Abstract

Moringa oleifera (M. oleifera) is globally recognized for its medicinal properties and offers high-quality, protein-rich seeds. This study aimed to explore the potential of M. oleifera seeds as a significant source of protein-based nanoparticles (PBNPs) using the ultrasonication technique after desolvation [...] Read more.

Moringa oleifera (M. oleifera) is globally recognized for its medicinal properties and offers high-quality, protein-rich seeds. This study aimed to explore the potential of M. oleifera seeds as a significant source of protein-based nanoparticles (PBNPs) using the ultrasonication technique after desolvation and to evaluate their cytotoxicity in the human leukemia cell line (THP-1) for the first time. The properties of the PBNPs were confirmed by dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). The extracted protein from moringa seed cake flour had a significant protein content of 54.20%, and the resulting PBNPs had an average size of 134.3 ± 0.47 nm with a robust zeta potential of −43.15 mV. Notably, our study revealed that PBNPs exhibited cytotoxic potential at high concentrations, especially against the THP-1 human leukemia cell line, which is widely used to study immunomodulatory properties. The inhibitory effect of PBNPs was quantitatively evidenced by a cytotoxicity assay, which showed that a concentration of 206.5 μg mL⁻¹ (log conc. 2.315) was required to inhibit 50% of biological activity. In conclusion, our findings highlight the potential of M. oleifera seeds as a valuable resource in the innovative field of eco-friendly PBNPs by combining traditional medicinal applications with contemporary advancements in protein nanotechnology. However, further studies are required to ensure their biocompatibility. Full article

(This article belongs to the Special Issue New Nanotechnology in the Agriculture and Food Industry)

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24 pages, 2857 KiB

Open AccessReview

Biological Nano-Agrochemicals for Crop Production as an Emerging Way to Address Heat and Associated Stresses

by József Prokisch, Aya Ferroudj, Safa Labidi, Hassan El-Ramady and Eric C. Brevik

Nanomaterials 2024, 14(15), 1253; https://doi.org/10.3390/nano14151253 - 26 Jul 2024

Abstract

Climate change is a global problem facing all aspects of the agricultural sector. Heat stress due to increasing atmospheric temperature is one of the most common climate change impacts on agriculture. Heat stress has direct effects on crop production, along with indirect effects [...] Read more.

Climate change is a global problem facing all aspects of the agricultural sector. Heat stress due to increasing atmospheric temperature is one of the most common climate change impacts on agriculture. Heat stress has direct effects on crop production, along with indirect effects through associated problems such as drought, salinity, and pathogenic stresses. Approaches reported to be effective to mitigate heat stress include nano-management. Nano-agrochemicals such as nanofertilizers and nanopesticides are emerging approaches that have shown promise against heat stress, particularly biogenic nano-sources. Nanomaterials are favorable for crop production due to their low toxicity and eco-friendly action. This review focuses on the different stresses associated with heat stress and their impacts on crop production. Nano-management of crops under heat stress, including the application of biogenic nanofertilizers and nanopesticides, are discussed. The potential and limitations of these biogenic nano-agrochemicals are reviewed. Potential nanotoxicity problems need more investigation at the local, national, and global levels, as well as additional studies into biogenic nano-agrochemicals and their effects on soil, plant, and microbial properties and processes. Full article

(This article belongs to the Section Environmental Nanoscience and Nanotechnology)

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15 pages, 3126 KiB

Open AccessArticle

Enhancing the Stability and Mobility of TFTs via Indium–Tungsten Oxide and Zinc Oxide Engineered Heterojunction Channels Annealed in Oxygen Ambient

by Seong-Hwan Lim, Dong-Gyun Mah and Won-Ju Cho

Nanomaterials 2024, 14(15), 1252; https://doi.org/10.3390/nano14151252 - 26 Jul 2024

Abstract

This study demonstrates a significant enhancement in the performance of thin-film transistors (TFTs) in terms of stability and mobility by combining indium–tungsten oxide (IWO) and zinc oxide (ZnO). IWO/ZnO heterojunction structures were fabricated with different channel thickness ratios and annealing environments. The IWO [...] Read more.

This study demonstrates a significant enhancement in the performance of thin-film transistors (TFTs) in terms of stability and mobility by combining indium–tungsten oxide (IWO) and zinc oxide (ZnO). IWO/ZnO heterojunction structures were fabricated with different channel thickness ratios and annealing environments. The IWO (5 nm)/ZnO (45 nm) TFT, annealed in O₂ ambient, exhibited a high mobility of 26.28 cm²/V·s and a maximum drain current of 1.54 μA at a drain voltage of 10 V, outperforming the single-channel ZnO TFT, with values of 3.8 cm²/V·s and 28.08 nA. This mobility enhancement is attributed to the formation of potential wells at the IWO/ZnO junction, resulting in charge accumulation and improved percolation conduction. The engineered heterojunction channel demonstrated superior stability under positive and negative gate bias stresses compared to the single ZnO channel. The analysis of O 1s spectra showed O_I, O_II, and O_III peaks, confirming the theoretical mechanism. A bias temperature stress test revealed superior charge-trapping time characteristics at temperatures of 25, 55, and 85 °C compared with the single ZnO channel. The proposed IWO/ZnO heterojunction channel overcomes the limitations of the single ZnO channel and presents an attractive approach for developing TFT-based devices having excellent stability and enhanced mobility. Full article

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11 pages, 1606 KiB

Open AccessArticle

Josephson Diode Effect in Parallel-Coupled Double-Quantum Dots Connected to Unalike Majorana Nanowires

by Yu-Mei Gao, Hu Xiao, Mou-Hua Jiang, Feng Chi, Zi-Chuan Yi and Li-Ming Liu

Nanomaterials 2024, 14(15), 1251; https://doi.org/10.3390/nano14151251 - 25 Jul 2024

Abstract

We study theoretically the Josephson diode effect (JDE) when realized in a system composed of parallel-coupled double-quantum dots (DQDs) sandwiched between two semiconductor nanowires deposited on an s-wave superconductor surface. Due to the combined effects of proximity-induced superconductivity, strong Rashba spin–orbit interaction, and [...] Read more.

We study theoretically the Josephson diode effect (JDE) when realized in a system composed of parallel-coupled double-quantum dots (DQDs) sandwiched between two semiconductor nanowires deposited on an s-wave superconductor surface. Due to the combined effects of proximity-induced superconductivity, strong Rashba spin–orbit interaction, and the Zeeman splitting inside the nanowires, a pair of Majorana bound states (MBSs) may possibly emerge at opposite ends of each nanowire. Different phase factors arising from the superconductor substrate can be generated in the coupling amplitudes between the DQDs and MBSs prepared at the left and right nanowires, and this will result in the Josephson current. We find that the critical Josephson currents in positive and negative directions are different from each other in amplitude within an oscillation period with respect to the magnetic flux penetrating through the system, a phenomenon known as the JDE. It arises from the quantum interference effect in this double-path device, and it can hardly occur in the system of one QD coupled to MBSs. Our results also show that the diode efficiency can reach up to

50 %

, but this depends on the overlap amplitude between the MBSs, as well as the energy levels of the DQDs adjustable by gate voltages. The present model is realizable within current nanofabrication technologies and may find practical use in the interdisciplinary field of Majorana and Josephson physics. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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24 pages, 2408 KiB

Open AccessReview

Carbon Dots in Photodynamic/Photothermal Antimicrobial Therapy

by Siqi Wang, Colin P. McCoy, Peifeng Li, Yining Li, Yinghan Zhao, Gavin P. Andrews, Matthew P. Wylie and Yi Ge

Nanomaterials 2024, 14(15), 1250; https://doi.org/10.3390/nano14151250 - 25 Jul 2024

Abstract

Antimicrobial resistance (AMR) presents an escalating global challenge as conventional antibiotic treatments become less effective. In response, photodynamic therapy (PDT) and photothermal therapy (PTT) have emerged as promising alternatives. While rooted in ancient practices, these methods have evolved with modern innovations, particularly through [...] Read more.

Antimicrobial resistance (AMR) presents an escalating global challenge as conventional antibiotic treatments become less effective. In response, photodynamic therapy (PDT) and photothermal therapy (PTT) have emerged as promising alternatives. While rooted in ancient practices, these methods have evolved with modern innovations, particularly through the integration of lasers, refining their efficacy. PDT harnesses photosensitizers to generate reactive oxygen species (ROS), which are detrimental to microbial cells, whereas PTT relies on heat to induce cellular damage. The key to their effectiveness lies in the utilization of photosensitizers, especially when integrated into nano- or micron-scale supports, which amplify ROS production and enhance antimicrobial activity. Over the last decade, carbon dots (CDs) have emerged as a highly promising nanomaterial, attracting increasing attention owing to their distinctive properties and versatile applications, including PDT and PTT. They can not only function as photosensitizers, but also synergistically combine with other photosensitizers to enhance overall efficacy. This review explores the recent advancements in CDs, underscoring their significance and potential in reshaping advanced antimicrobial therapeutics. Full article

(This article belongs to the Special Issue Carbon Nanostructures as Promising Future Materials: 2nd Edition)

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37 pages, 4585 KiB

Open AccessReview

Carbon Nanodot–Microbe–Plant Nexus in Agroecosystem and Antimicrobial Applications

by József Prokisch, Duyen H. H. Nguyen, Arjun Muthu, Aya Ferroudj, Abhishek Singh, Shreni Agrawal, Vishnu D. Rajput, Karen Ghazaryan, Hassan El-Ramady and Mahendra Rai

Nanomaterials 2024, 14(15), 1249; https://doi.org/10.3390/nano14151249 - 25 Jul 2024

Abstract

The intensive applications of nanomaterials in the agroecosystem led to the creation of several environmental problems. More efforts are needed to discover new insights in the nanomaterial–microbe–plant nexus. This relationship has several dimensions, which may include the transport of nanomaterials to different plant [...] Read more.

The intensive applications of nanomaterials in the agroecosystem led to the creation of several environmental problems. More efforts are needed to discover new insights in the nanomaterial–microbe–plant nexus. This relationship has several dimensions, which may include the transport of nanomaterials to different plant organs, the nanotoxicity to soil microbes and plants, and different possible regulations. This review focuses on the challenges and prospects of the nanomaterial–microbe–plant nexus under agroecosystem conditions. The previous nano-forms were selected in this study because of the rare, published articles on such nanomaterials. Under the study’s nexus, more insights on the carbon nanodot–microbe–plant nexus were discussed along with the role of the new frontier in nano-tellurium–microbe nexus. Transport of nanomaterials to different plant organs under possible applications, and translocation of these nanoparticles besides their expected nanotoxicity to soil microbes will be also reported in the current study. Nanotoxicity to soil microbes and plants was investigated by taking account of morpho-physiological, molecular, and biochemical concerns. This study highlights the regulations of nanotoxicity with a focus on risk and challenges at the ecological level and their risks to human health, along with the scientific and organizational levels. This study opens many windows in such studies nexus which are needed in the near future. Full article

(This article belongs to the Special Issue Environmental Fate, Transport and Effects of Nanoplastics)

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14 pages, 4422 KiB

Open AccessArticle

Controlled Morphological Growth and Photonic Lasing in Cesium Lead Bromide Microcrystals

by Mamoon Ur Rashid, Zeeshan Tahir, Muhammad Sheeraz, Farman Ullah, Yun Chang Park, Faisal Maqbool and Yong Soo Kim

Nanomaterials 2024, 14(15), 1248; https://doi.org/10.3390/nano14151248 - 25 Jul 2024

Abstract

Morphology plays a crucial role in defining the optical, electronic, and mechanical properties of halide perovskite microcrystals. Therefore, developing strategies that offer precise control over crystal morphology during the growth process is highly desirable. This work presents a simple scheme to simultaneously grow [...] Read more.

Morphology plays a crucial role in defining the optical, electronic, and mechanical properties of halide perovskite microcrystals. Therefore, developing strategies that offer precise control over crystal morphology during the growth process is highly desirable. This work presents a simple scheme to simultaneously grow distinct geometries of cesium lead bromide (CsPbBr₃) microcrystals, including microrods (MR), microplates (MP), and microspheres (MS), in a single chemical vapor deposition (CVD) experiment. By strategically adjusting precursor evaporation temperatures, flux density, and the substrate temperature, we surpass previous techniques by achieving simultaneous yet selective growth of multiple CsPbBr₃ geometries at distinct positions on the same substrate. This fine growth control is attributed to the synergistic variation in fluid flow dynamics, precursor substrate distance, and temperature across the substrate, offering regions suitable for the growth of different morphologies. Pertinently, perovskite MR are grown at the top, while MP and MS are observed at the center and bottom regions of the substrate, respectively. Structural analysis reveals high crystallinity and an orthorhombic phase of the as-grown perovskite microcrystals, while persistent photonic lasing manifests their nonlinear optical characteristics, underpinning their potential application for next-generation photonic and optoelectronic devices. Full article

(This article belongs to the Special Issue Nonlinear Optics in Low-Dimensional Nanomaterials)

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Graphical abstract

13 pages, 3701 KiB

Open AccessArticle

Rheological Behavior of an Aqueous Suspension of Oxidized Carbon Nanohorn (CNHox)

by Ayumi Moteki and Motoyoshi Kobayashi

Nanomaterials 2024, 14(15), 1247; https://doi.org/10.3390/nano14151247 - 25 Jul 2024

Abstract

Oxidized carbon nanohorn (CNHox) a carbon nanomaterial that has attracted attention due to its unique material properties. It is expected to be applied in various areas like cancer treatment, gene-expression technology, fluids with high thermal conductivity, lubricants, and so on. While the rheological [...] Read more.

Oxidized carbon nanohorn (CNHox) a carbon nanomaterial that has attracted attention due to its unique material properties. It is expected to be applied in various areas like cancer treatment, gene-expression technology, fluids with high thermal conductivity, lubricants, and so on. While the rheological measurements of suspensions provide information on the effective size and interactions of suspended particles, the rheological behaviors of aqueous suspensions of CNHox have never been systematically investigated. To clarify the rheological behaviors of aqueous suspensions of CNHox, their viscosity and dynamic viscoelasticity were measured with changing particle concentration and salt concentration. The viscosity of a CNHox suspension showed yield stress at low shear rates and showed shear-thinning behavior with increasing shear rates. The viscosity of 5 weight % CNHox suspensions was comparable to that of 60 weight % silica suspensions. This high viscosity at a low CNHox concentration is probably due to the porous structure and large effective volume of the CNHox particle. The estimated effective volume of CNHox calculated by the Krieger−Dougherty equation was 18.9 times larger than the actual volume calculated by the mass concentration and density. The dependence of rheological behavior of the CNHox suspension on salt concentration was weak compared to that of the colloidal silica suspension. This weak dependence on salt concentration may be due to the roughness of the particle surface, which would weaken the effect of electric double-layer interactions and/or van der Waals interactions between particles. These rheological behaviors of the aqueous suspension of CNHox shown in this research will be useful in efforts to improve the efficiency of its utilization for the various applications. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

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19 pages, 4820 KiB

Open AccessArticle

Fluorescent Aromatic Polyether Sulfones: Processable, Scalable, Efficient, and Stable Polymer Emitters and Their Single-Layer Polymer Light-Emitting Diodes

by Konstantinos C. Andrikopoulos, Despoina Tselekidou, Charalampos Anastasopoulos, Kyparisis Papadopoulos, Vasileios Kyriazopoulos, Stergios Logothetidis, Joannis K. Kallitsis, Maria Gioti and Aikaterini K. Andreopoulou

Nanomaterials 2024, 14(15), 1246; https://doi.org/10.3390/nano14151246 - 25 Jul 2024

Abstract

In this study, fully aromatic polyether sulfones were developed, bearing blue, yellow, and orange–red π-conjugated semiconducting units. Carbazole-, anthracene-, and benzothiadiazole-based fluorophores are copolymerized with a diphenylsulfone moiety. A diphenylpyridine comonomer was additionally utilized, acting as both a solubilizing unit and a weak [...] Read more.

In this study, fully aromatic polyether sulfones were developed, bearing blue, yellow, and orange–red π-conjugated semiconducting units. Carbazole-, anthracene-, and benzothiadiazole-based fluorophores are copolymerized with a diphenylsulfone moiety. A diphenylpyridine comonomer was additionally utilized, acting as both a solubilizing unit and a weak blue fluorescent group. Using this rationale, fluorescent polyarylethers with high molecular weights, up to 70 kDa, were developed, showing film formation ability and high thermal stability, while preserving excellent solubility in common organic, nonvolatile, and nonchlorinated solvents. Fine-tuning of the emission color was achieved through subtle changes of the comonomers’ type and ratio. Single-chromophore-bearing copolymers emitted in the blue or the yellow region of the visible spectrum, while the dual-chromophore-bearing terpolymers emitted throughout the visible spectrum, resulting in white light emission. Solutions of 20 wt% in polar aprotic solvents at ambient conditions allowed the deposition of fluorescent copolyethers and printing from non-chlorinated solvents. All polyethers were evaluated for their structural and optoelectronic properties, and selected copolymers were successfully used in the emitting layer (EML) of organic light-emitting diode (OLED) devices, using either rigid or flexible substrates. Remarkable color stability was displayed in all cases for up to 15 V of bias voltage. The Commission Internationale de L’Eclairage (CIE) of the fabricated devices is located in the blue (0.16, 0.16), yellow (0.44, 0.50), or white region of the visible spectrum (0.33, 0.38) with minimal changes according to the ratio of the comonomers. The versatile methodology toward semiconducting polyethersulfones for polymer light-emitting diodes (PLEDs) developed herein led to the scaled-up production of luminescent polymers of up to 25 g of high-molecular-weight single batches, demonstrating the effectiveness of this approach as a straightforward tool to facilitate the synthesis of flexible and printable EMLs for large-area PLED coverage. Full article

(This article belongs to the Section Nanophotonics Materials and Devices)

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17 pages, 2591 KiB

Open AccessArticle

High Magnetic Performance in MnGa Nanocomposite Magnets

by Ovidiu Crisan and Alina Daniela Crisan

Nanomaterials 2024, 14(15), 1245; https://doi.org/10.3390/nano14151245 - 24 Jul 2024

Abstract

In view of their potential applicability in technology fields where magnets are required to operate at higher temperatures, the class of nanocomposite magnets with little or no rare earth (RE) content has been widely researched in the last two decades. Among these nanocomposite [...] Read more.

In view of their potential applicability in technology fields where magnets are required to operate at higher temperatures, the class of nanocomposite magnets with little or no rare earth (RE) content has been widely researched in the last two decades. Among these nanocomposite magnets, the subclass of magnetic binary systems exhibiting the formation of L1₀ tetragonal phases is the most illustrious. Some of the most interesting systems are represented by the Mn-based alloys, with addition of Al, Bi, Ga, Ge. Such alloys are interesting as they are less costly than RE magnets and they show promising magnetic properties. The paper tackles the case of MnGa binary alloys with various compositions around the Mn₃Ga stoichiometry. Four MnGa magnetic alloys, with Mn content ranging from 70 at% to 75 at% were produced using rapid solidification to form the melt. By combining structural information arising from X-ray diffractometry and transmission electron microscopy with magnetic properties determined by vibrating sample magnetometry, we are able to document the nature and properties of the structural phases formed in the alloys in their as-cast state and upon annealing, the evolution of the phase structure after annealing and its influence on the magnetic behavior of the MnGa alloys. After annealing at 400 °C and 500 °C, MnGa alloys are showing a multiple-phase microstructure, consisting of co-existing crystallites of L1₀ and D0₂₂ tetragonal phase. As a consequence of these structurally and magnetically different phases, co-existing within the microstructure, promising magnetic features are obtained, with both coercive fields and saturation magnetization exceeding values previously reported for both alloys and layers of MnGa. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Magnets with the L10 Phase)

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18 pages, 3264 KiB

Open AccessReview

Silver Nanocomposites with Enhanced Shelf-Life for Fruit and Vegetable Preservation: Mechanisms, Advances, and Prospects

by Xin Ding, Huan Lin, Jie Zhou, Zhihao Lin, Yanyan Huang, Ge Chen, Yanguo Zhang, Jun Lv, Jing Chen, Guangyang Liu, Xiaomin Xu and Donghui Xu

Nanomaterials 2024, 14(15), 1244; https://doi.org/10.3390/nano14151244 - 24 Jul 2024

Abstract

Reducing fruit and vegetable waste and maintaining quality has become challenging for everyone. Nanotechnology is a new and intriguing technology that is currently being implemented in fruit and vegetable preservation. Silver nanomaterials provide superior antibacterial qualities, biodegradability, and biocompatibility, which expands their potential [...] Read more.

Reducing fruit and vegetable waste and maintaining quality has become challenging for everyone. Nanotechnology is a new and intriguing technology that is currently being implemented in fruit and vegetable preservation. Silver nanomaterials provide superior antibacterial qualities, biodegradability, and biocompatibility, which expands their potential applications in fruit and vegetable preservation. Silver nanomaterials include silver nanocomposites and Ag-MOF, of which silver nanocomposites are mainly composed of silver nanoparticles. Notably, not all kinds of silver nanoparticles utilized in the preservation of fruits and vegetables are thoroughly described. Therefore, the synthesis, mechanism of action, and advancements in research on silver nanocomposites for fruit and vegetable preservation were discussed in this study. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanotechnology for Food Safety)

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13 pages, 2076 KiB

Open AccessArticle

Stereolithography 3D Printing of Stimuli-Responsive Spin Crossover@Polymer Nanocomposites with Optimized Actuating Properties

by Onkar Kulkarni, Alejandro Enriquez-Cabrera, Xinyu Yang, Julie Foncy, Liviu Nicu, Gábor Molnár and Lionel Salmon

Nanomaterials 2024, 14(15), 1243; https://doi.org/10.3390/nano14151243 - 24 Jul 2024

Abstract

We used stereolithography to print polymer nanocomposite samples of stimuli-responsive spin crossover materials in the commercial photo-curable printing resins DS3000 and PEGDA-250. The thermomechanical analysis of the SLA-printed objects revealed not only the expected reinforcement of the polymer resins by the introduction of [...] Read more.

We used stereolithography to print polymer nanocomposite samples of stimuli-responsive spin crossover materials in the commercial photo-curable printing resins DS3000 and PEGDA-250. The thermomechanical analysis of the SLA-printed objects revealed not only the expected reinforcement of the polymer resins by the introduction of the stiffer SCO particles, but also a significant mechanical damping, as well as a sizeable linear strain around the spin transition temperatures. For the highest accessible loads (ca. 13–15 vol.%) we measured transformation strains in the range of 1.2–1.5%, giving rise to peaks in the coefficient of thermal expansion as high as 10⁻³ °C⁻¹, which was exploited in 3D printed bilayer actuators to produce bending movement. The results pave the way for integrating these advanced stimuli-responsive composites into mechanical actuators and 4D printing applications. Full article

(This article belongs to the Topic Advanced Polymeric Composites: Processing, Characterization and Mechanical Behavior)

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11 pages, 3295 KiB

Open AccessArticle

Chemical Orderings in CuCo Nanoparticles: Topological Modeling Using DFT Calculations

by Konstantin M. Neyman and Pere Alemany

Nanomaterials 2024, 14(15), 1242; https://doi.org/10.3390/nano14151242 - 24 Jul 2024

Abstract

The orderings of atoms in bimetallic 1.6–2.1 nm-large CuCo nanoparticles, important as catalytic and magnetic materials, were studied using a combination of DFT calculations with a topological approach. The structure and magnetism of Cu₅₀Co₁₅₁, Cu₁₀₁Co₁₀₀, [...] Read more.

The orderings of atoms in bimetallic 1.6–2.1 nm-large CuCo nanoparticles, important as catalytic and magnetic materials, were studied using a combination of DFT calculations with a topological approach. The structure and magnetism of Cu₅₀Co₁₅₁, Cu₁₀₁Co₁₀₀, Cu₁₅₁Co₅₀, and Cu₃₀₃Co₁₀₂ nanoparticles; their resistance to disintegrating into separate Cu and Co species; as well as the exposed surface sites, were quantified and analyzed, showing a clear preference for Cu atoms to occupy surface positions while the Co atoms tended to form a compact cluster in the interior of the nanoparticles. The surface segregation of Co atoms that are encapsulated by less-active Cu atoms, induced by the adsorption of CO molecules, was already enabled at a low coverage of adsorbed CO, providing the energy required to displace the entire compact Co species inside the Cu matrices due to a notable adsorption preference of CO for the Co sites over the Cu ones. The calculated adsorption energies and vibrational frequencies of adsorbed CO should be helpful indicators for experimentally monitoring the nature of the surface sites of CuCo nanoparticles, especially in the case of active Co surface sites emerging in the presence of CO. Full article

(This article belongs to the Section Energy and Catalysis)

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19 pages, 5369 KiB

Open AccessArticle

What Are the Key Factors for the Detection of Peptides Using Mass Spectrometry on Boron-Doped Diamond Surfaces?

by Juvissan Aguedo, Marian Vojs, Martin Vrška, Marek Nemcovic, Zuzana Pakanova, Katerina Aubrechtova Dragounova, Oleksandr Romanyuk, Alexander Kromka, Marian Varga, Michal Hatala, Marian Marton and Jan Tkac

Nanomaterials 2024, 14(15), 1241; https://doi.org/10.3390/nano14151241 - 24 Jul 2024

Abstract

We investigated the use of boron-doped diamond (BDD) with different surface morphologies for the enhanced detection of nine different peptides by matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS). For the first time, we compared three different nanostructured BDD film morphologies (Continuous, Nanograss, and Nanotips) [...] Read more.

We investigated the use of boron-doped diamond (BDD) with different surface morphologies for the enhanced detection of nine different peptides by matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS). For the first time, we compared three different nanostructured BDD film morphologies (Continuous, Nanograss, and Nanotips) with differently terminated surfaces (-H, -O, and -F) to commercially available Ground Steel plates. All these surfaces were evaluated for their effectiveness in detecting the nine different peptides by MALDI-MS. Our results demonstrated that certain nanostructured BDD surfaces exhibited superior performance for the detection of especially hydrophobic peptides (e.g., bradykinin 1–7, substance P, and the renin substrate), with a limit of detection of down to 2.3 pM. Further investigation showed that hydrophobic peptides (e.g., bradykinin 1–7, substance P, and the renin substrate) were effectively detected on hydrogen-terminated BDD surfaces. On the other hand, the highly acidic negatively charged peptide adrenocorticotropic hormone fragment 18–39 was effectively identified on oxygen-/fluorine-terminated BDD surfaces. Furthermore, BDD surfaces reduced sodium adduct contamination significantly. Full article

(This article belongs to the Special Issue Carbon-Based Nanomaterials for Biomedicine Applications)

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9 pages, 4965 KiB

Open AccessCommunication

Fabrication of Non-Wetting Mg(OH)₂ Composites with Photoresponsive Capabilities and Their Environmental Restoration Performance

by Dongmei Zhang, Jiaqi Zhao, Yangyang Peng, Yuchao Li, Wenbin Guo and Chengzhu Liao

Nanomaterials 2024, 14(15), 1240; https://doi.org/10.3390/nano14151240 - 24 Jul 2024

Abstract

Water pollution seriously affects the development of society and human life. There are various kinds of pollutants, including soluble pollutants and insoluble floaters on the water surface. Herein, the photocatalyst semiconductor BiOCl and superhydrophobic functional particles Mg(OH)₂ were deposited on the surfaces [...] Read more.

Water pollution seriously affects the development of society and human life. There are various kinds of pollutants, including soluble pollutants and insoluble floaters on the water surface. Herein, the photocatalyst semiconductor BiOCl and superhydrophobic functional particles Mg(OH)₂ were deposited on the surfaces of canvas and polyester felt to construct superhydrophobic canvas and polyester felt. The contact angles of the synthetic superhydrophobic canvas and polyester felt were measured as 152° and 155.3°, respectively. The selective adsorption of hexadecane was achieved using the wetting difference between the surface of water and pollutants floating on the surface. For dissolved pollutants, the surface wettability needed to be changed with the help of ethanol. The degradation efficiencies were all greater than 90%, demonstrating the versatility of the synthetic superhydrophobic canvas and polyester felt. Full article

(This article belongs to the Special Issue Hierarchical Nanostructured Materials for Multifunctional Applications)

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