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Appl. Nano, Volume 2, Issue 1 (March 2021) – 7 articles

Cover Story (view full-size image): Effects of expandable graphite (EGr) at relatively high loadings, up to 55 wt%, in amorphous polystyrene and semicrystalline polyethylene matrices are investigated. EGr forms conductive paths for electrons at >8 wt%, whereas not for heat transport (phonons). The electrical and thermal conductivities increase with the filler loading for both matrices, respectively. Heat transport is hindered in amorphous nanocomposites due to scattering effects at the polymer–filler interface, whereas it is enhanced in the semicrystalline matrix due to percolation of crystallites and the corresponding interfacial amorphous–crystalline polymer zones (ordered structures). The latter phenomena are enhanced by the presence of EGr, which is an indirect filler effect, and indicate the potential of tailor-made materials for wanted applications. View this paper
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Editorial
Formation of Advanced Nanomaterials by Gas-Phase Aggregation
Appl. Nano 2021, 2(1), 82-84; https://0-doi-org.brum.beds.ac.uk/10.3390/applnano2010007 - 19 Mar 2021
Viewed by 563
Abstract
Gas aggregation is a well-known phenomenon, often seen in nature under temperature lowering, as, for example, cloud, fog or haze formation [...] Full article
(This article belongs to the Special Issue Formation of Advanced Nanomaterials by Gas-Phase Aggregation)
Article
Removal of Cyanotoxins–Microcystins from Water by Filtration through Granulated Composites of Bentonite with Micelles of the Cation Octadecyltrimethyl Ammonium (ODTMA)
Appl. Nano 2021, 2(1), 67-81; https://0-doi-org.brum.beds.ac.uk/10.3390/applnano2010006 - 10 Mar 2021
Cited by 2 | Viewed by 1040
Abstract
Cyanobacteria and their toxins present potential hazards to consumers of water from lakes, reservoirs and rivers; thus, their removal via water treatment is essential. Previously, we demonstrated that nanocomposites of octadecyltrimethyl ammonium (ODTMA) complexed with clay could efficiently remove cyanobacteria and their toxins [...] Read more.
Cyanobacteria and their toxins present potential hazards to consumers of water from lakes, reservoirs and rivers; thus, their removal via water treatment is essential. Previously, we demonstrated that nanocomposites of octadecyltrimethyl ammonium (ODTMA) complexed with clay could efficiently remove cyanobacteria and their toxins from laboratory cultures and lake water. In this study, we determined the capacity of ODTMA nanocomposites to remove cyanotoxins, namely microcystins (MCs), from water to below 1 µg/L via filtration. This capacity was 1500 mg MC-LR per Kg of nanocomposite. Similar capacities were estimated for the removal of other MC congeners (MC-WR, MC-3aspWR and MC-YR), whereas substantially lower capacities were recorded for more positively charged MC congeners, such as MC-RR and MC-3aspRR. Filtration results were simulated with a filtration model, which considers convection and adsorption/desorption of one to several toxins. Model calculations for the removal of MC-LR, under a variety of situations, fitted well with all the experimentally measured values and also estimated the co-removal of several MC congeners. In agreement with model predictions, results demonstrated that in the presence of MC-WR, the emerging concentrations of MC-RR congeners eventually exceed their solution values. In conclusion, granulated nanocomposites of ODTMA–bentonite can be applied for the removal of microcystins from drinking water. Full article
(This article belongs to the Collection Feature Papers for Applied Nano)
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Article
RF Sputter-Deposited Nanostructured CuO Films for Micro-Supercapacitors
Appl. Nano 2021, 2(1), 46-66; https://0-doi-org.brum.beds.ac.uk/10.3390/applnano2010005 - 25 Feb 2021
Cited by 1 | Viewed by 674
Abstract
Copper oxide is considered as an alternative electrode material for supercapacitors due to its low cost, chemical stability and high theoretical specific capacitance. In the present work, nanostructured copper oxide (CuO) films are prepared by radio-frequency (RF) magnetron sputtering, and the influence of [...] Read more.
Copper oxide is considered as an alternative electrode material for supercapacitors due to its low cost, chemical stability and high theoretical specific capacitance. In the present work, nanostructured copper oxide (CuO) films are prepared by radio-frequency (RF) magnetron sputtering, and the influence of the substrate temperature on the microstructure and supercapacitive properties was studied. The copper oxide films prepared at 350 °C exhibit a predominant (1¯11) orientation corresponding to the monoclinic Cu(II)O phase with a crystallite size of 24 nm. The surface of the film consists of uniformly distributed oval-like grains providing a high surface roughness of 45 nm. The films exhibit an optical bandgap of 1.68 ± 0.01 eV and an electrical conductivity of 0.4 S cm−1 at room temperature. The as-prepared CuO films deliver a discharge specific capacitance of 387 mF cm−2 (375 F g−1) at a current density of 1 mA cm−2 with excellent cyclic capacitance retention of 95% (367 mF cm−2) even after 1000 cycles. Hence, these films are potential electrodes for micro-supercapacitors. Full article
(This article belongs to the Collection Feature Papers for Applied Nano)
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Article
Effects of Expandable Graphite at Moderate and Heavy Loadings on the Thermal and Electrical Conductivity of Amorphous Polystyrene and Semicrystalline High-Density Polyethylene
Appl. Nano 2021, 2(1), 31-45; https://0-doi-org.brum.beds.ac.uk/10.3390/applnano2010004 - 25 Feb 2021
Viewed by 594
Abstract
In this work, we prepared and investigated two series of polymer composites, wherein the matrix was either an amorphous polystyrene (PS) or a semicrystalline high-density polyethylene (HDPE) filled with expandable graphite (EGr) at relatively high loadings within the range 5–55 wt %. For [...] Read more.
In this work, we prepared and investigated two series of polymer composites, wherein the matrix was either an amorphous polystyrene (PS) or a semicrystalline high-density polyethylene (HDPE) filled with expandable graphite (EGr) at relatively high loadings within the range 5–55 wt %. For the investigation we employed a thermogravimetric analysis and differential scanning calorimetry to assess the thermal transitions and evaluate the various polymer fractions (crystalline (CF), mobile (MAF) and rigid amorphous (RAF)) in addition to broadband dielectric spectroscopy and a laser flash analysis to evaluate the EGr effects on electrical conductivity, σ, and thermal conductivity, λ, respectively. In PS, EGr was found to impose an increase of the glass transition temperature and a systematic decrease of the corresponding heat capacity change. The latter was rationalized in terms of the formation of an interfacial RAF. No glass transition was recorded for HDPE whereas the fillers increased the CF moderately. As expected, σ increased with the filler loading for both matrices, up to 10−3–10−2 S/cm, resulting in a conductive percolation threshold for electrons at > 8 wt % EGr. Simultaneously, the λ of PS and HDPE were strongly increased, from 0.13 and 0.38 W·K–1·m–1 up to 0.55 and ~2 W·K–1·m–1, respectively. λ demonstrated an almost linear EGr loading dependence whereas the semicrystalline composites exhibited a systematically higher λ. Full article
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Article
Influence of the Parameters of Cluster Ions on the Formation of Nanostructures on the KTP Surface
Appl. Nano 2021, 2(1), 25-30; https://0-doi-org.brum.beds.ac.uk/10.3390/applnano2010003 - 23 Jan 2021
Cited by 1 | Viewed by 572
Abstract
In this work, the formation of periodic nanostructures on the surface of potassium titanyl phosphate (KTP) has been demonstrated. The surface of KTP single crystals after the processing of argon cluster ions with different energy per cluster atom E/Nmean = [...] Read more.
In this work, the formation of periodic nanostructures on the surface of potassium titanyl phosphate (KTP) has been demonstrated. The surface of KTP single crystals after the processing of argon cluster ions with different energy per cluster atom E/Nmean = 12.5 and 110 eV/atom has been studied using atomic force microscopy (AFM). To characterize the nanostructures, the power spectral density (PSD) functions have been used. The features of the formation of periodic nanostructures are revealed depending on the incident angle of clusters and different energy per atom in clusters. Full article
(This article belongs to the Special Issue Formation of Advanced Nanomaterials by Gas-Phase Aggregation)
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Article
Extending the Shelf Life of Strawberries by the Sonochemical Coating of their Surface with Nanoparticles of an Edible Anti-Bacterial Compound
Appl. Nano 2021, 2(1), 14-24; https://0-doi-org.brum.beds.ac.uk/10.3390/applnano2010002 - 04 Jan 2021
Viewed by 758
Abstract
The current paper presents the coating of harvested strawberries with edible nanoparticles of Chitosan. The NPs were formed by the application of ultrasonic waves on an acidic solution of chitosan. In a one-step process the nanoparticles were created and subsequent to their formation [...] Read more.
The current paper presents the coating of harvested strawberries with edible nanoparticles of Chitosan. The NPs were formed by the application of ultrasonic waves on an acidic solution of chitosan. In a one-step process the nanoparticles were created and subsequent to their formation they were deposited on the strawberries surface. The shelf life of the NPs coated was compared with the deposition of the same amount of non-sonicated chitosan, i.e., coating of individual chitosan molecules on the fruit. The characterization of the coated fruits was carried out by monitoring the weight loss. TSS (total soluble solids), pH, TA (titratable acidity), and Vitamin C. Finally, the freshness of the strawberries was determined by eye observation. In addition, the characterization of the chitosan NPs was also conducted in this study by (DLS) dynamic light scattering and (SEM) scanning electron microscopy. Full article
(This article belongs to the Collection Feature Papers for Applied Nano)
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Article
Palladium-Nanoparticles Biohybrids in Applied Chemistry
Appl. Nano 2021, 2(1), 1-13; https://0-doi-org.brum.beds.ac.uk/10.3390/applnano2010001 - 29 Dec 2020
Cited by 6 | Viewed by 801
Abstract
Applied nanotechnology has experienced tremendous advance over the last decade. In this study, the efficient synthesis of highly stable palladium-nanoparticles (PdNPs) biohybrids based on the application of an enzyme, which induces in situ the generation of spherical nanoparticles on the protein network, has [...] Read more.
Applied nanotechnology has experienced tremendous advance over the last decade. In this study, the efficient synthesis of highly stable palladium-nanoparticles (PdNPs) biohybrids based on the application of an enzyme, which induces in situ the generation of spherical nanoparticles on the protein network, has been described. A heterogeneous material was synthesized formed with PdNPs with average sizes between 1.5 to 5 nm. These Pd nanocatalysts were successfully applied in different chemical processes: C-C bonding reactions (Suzuki and Heck reactions) and cascade processes combining enzymatic and metallic activities (hydrolysis-reduction, esterification-racemization). Full article
(This article belongs to the Collection Feature Papers for Applied Nano)
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