Search Results (18)

Fully bio-based composites were obtained from continuous bamboo strips and flame-retardant polyamide 11 (PA11-FR) matrix. A mercerization treatment was performed on the bamboo strips surface to optimize fiber-matrix interactions. Composites were obtained by thermocompression molding with two pressure plateaus. The influence of the concentration of NaOH solution treatment was analyzed. The thermogravimetric analysis highlighted that the mercerization treatment removes part of hemicellulose, low molecular weight lignin and amorphous cellulose, while crystalline cellulose is preserved. Dynamic mechanical analysis performed in the shear configuration revealed the level of interactions between bamboo strips and PA11-FR matrix. The glassy modulus was improved for the composites compared to the matrix and their rubbery modulus was increased by a factor 4.6. Composites with bamboo strips treated at 1% NaOH showed the highest shear modulus across the entire temperature range with an increase by a factor of 1.39 on the glassy plateau and 1.3 on the rubbery plateau, with the untreated bamboo strips/polyamide 11-FR composite as reference. Water uptake was analogous for composites and bamboo strips, so the shear modulus at room temperature was not impacted by moisture. Full article

Herein, a method to upcycle polyacrylonitrile (PAN) into high-sulfur-content materials (HSMs) by reacting 10 wt. % PAN with 90 wt. % elemental sulfur at 220 °C is reported. The resulting composites (PANS₉₀) form glassy solids that display compressive, flexural, and tensile strengths comparable to or exceeding some common construction materials, including C62 brick. Comparison to other plastic-derived HSMs indicates that PANS₉₀ exhibits mechanical properties including compressional strength (11.4 MPa), flexural strength (3.6 MPa) and tensile strength (2.5 MPa) within a similar or slightly improved range. Mechanistic investigations using small-molecule analogs (e.g., adiponitrile) suggest that thiophene ring formation and radical-driven sulfur–carbon bond formation are key reaction pathways, contributing to the composite’s crosslinked microstructure. Preliminary life cycle assessments estimate a global warming potential for PANS₉₀ (0.33 kg CO₂e/kg) that is about three times lower than that of Ordinary Portland Cement, underscoring its reduced environmental footprint. Overall, this sulfur-based upcycling strategy addresses two pressing waste-management concerns—surplus sulfur from petroleum refining and unrecycled PAN—while furnishing robust composites suitable for applications ranging from lightweight construction materials to specialty polymer systems. Full article

This work demonstrates the successful application of the picein wax carbon composite electrode (PWCCE) for profiling both commercial and homemade plant milks. Picein wax was utilized as an unconventional binder. The resulting electrode paste exhibited a solidified and hard texture, enabling its use in a manner analogous to that of the glassy carbon electrode. Differential pulse voltammetry (DPV) with an automated measurement and recording procedure was employed to obtain plant-based milk profiles. The utilization of operator-independent measurement procedures yielded high-quality electrochemical fingerprints suitable for subsequent calculations. To interpret the data, unsupervised machine learning methods were implemented, such as principal component analysis (PCA) and cluster analysis. These chemometric techniques confirmed the electrode effectiveness of the construction for this type of research. Moreover, they proved valuable in distinguishing between plant-based milk and cow’s milk, including two different variants: whole milk and lactose-free milk. Full article

Two analytical methods previously developed by our groups were employed to estimate the antioxidant capacity of commercial fruit juices. The electrochemical method, which measures the scavenging activity of antioxidants towards OH radicals generated by both hydrogen peroxide photolysis and Fenton’s reaction, is based on the recovery of the cyclic voltametric response of the redox probe Ru(NH₃)₆³⁺ at a Glassy Carbon electrode modified with a thin film of an insulating polyphenol, in the presence of compounds with antioxidant properties. The values of the antioxidant capacity of the fruit juices are expressed as vitamin C equivalents/L. The chromatographic method is based on the generation of OH radicals via Fenton’s reaction in order to test the inhibition of their formation in the presence of antioxidant compounds by monitoring salicylate aromatic hydroxylation derivatives as markers of •OH production, by means of HPLC coupled to coulometric detection. The results are expressed as the percentage of inhibition of •OH production in the presence of the tested juice compared to the control sample. When OH radicals are produced by Fenton’s reaction, the antioxidant capacity of the juices, estimated by both methods, displays an analogous trend, confirming that they can be considered an alternative for measuring the ability of antioxidants to block OH radical formation. Full article

The global consumption of vegan foods is experiencing an expressive upward trend, underscoring the critical need for quality control measures based on nutritional and functional considerations. This study aimed to evaluate the functional quality of caviar and salmon analog food inks based on pulses combined with nano ingredients and produced in our laboratory (LNANO). The primary objective of this work was to determine the total antioxidant compounds contained in these samples using a voltammetric technique with a glassy carbon electrode. The samples underwent ethanolic extraction (70%) with 1 h of stirring. The voltammograms were acquired in a phosphate buffer electrolyte, pH 3.0 with Ag/AgCl (KCl 3 mol L⁻¹) as the reference electrode and platinum wire as the auxiliary electrode. The voltammograms revealed prominent anodic current peaks at 0.76–0.78 V, which are attributed to isoflavones. Isoflavones, known secondary metabolites with substantial antioxidant potential commonly found in pulses, were identified. The total isoflavone concentrations obtained ranged from 31.5 to 64.3 mg Eq genistein 100 g⁻¹. The results not only validated the efficacy of the electrochemical sensor for quantifying total antioxidant compounds in the samples but also demonstrated that the concentration of total isoflavones in caviar and salmon analogs fell within the expected limits. Full article

Catalytically active nanomaterials, in particular, nanozymes, are promising candidates for applications in biosensors due to their excellent catalytic activity, stability and cost-effective preparation. Nanozymes with peroxidase-like activities are prospective candidates for applications in biosensors. The purpose of the current work is to develop cholesterol oxidase-based amperometric bionanosensors using novel nanocomposites as peroxidase (HRP) mimetics. To select the most electroactive chemosensor on hydrogen peroxide, a wide range of nanomaterials were synthesized and characterized using cyclic voltammetry (CV) and chronoamperometry. Pt NPs were deposited on the surface of a glassy carbon electrode (GCE) in order to improve the conductivity and sensitivity of the nanocomposites. The most HRP-like active bi-metallic CuFe nanoparticles (nCuFe) were placed on a previously nano-platinized electrode, followed by conjugation of cholesterol oxidase (ChOx) in a cross-linking film formed by cysteamine and glutaraldehyde. The constructed nanostructured bioelectrode ChOx/nCuFe/nPt/GCE was characterized by CV and chronoamperometry in the presence of cholesterol. The bionanosensor (ChOx/nCuFe/nPt/GCE) shows a high sensitivity (3960 A·M⁻¹·m⁻²) for cholesterol, a wide linear range (2–50 µM) and good storage stability at a low working potential (−0.25 V vs. Ag/AgCl/3 M KCl). The constructed bionanosensor was tested on a real serum sample. A detailed comparative analysis of the bioanalytical characteristics of the developed cholesterol bionanosensor and the known analogs is presented. Full article

Recently, an interest in NASICON-type materials revived, as they are considered potential cathode materials in sodium–ion batteries used in large-scale energy storage. We applied a facile technique of thermal nanocrystallization of glassy analogs of these compounds to enhance their electrical parameters. Six nanomaterials of the Na₃M₂(PO₄)₂F₃ (M = V, Ti, Fe) system were studied. Samples with nominal compositions of Na₃V₂(PO₄)₂F₃, Na₃Ti₂(PO₄)₂F₃, Na₃Fe₂(PO₄)₂F₃, Na₃TiV(PO₄)₂F₃, Na₃FeV(PO₄)₂F₃ and Na₃FeTi(PO₄)₂F₃ have been synthesized as glasses using the melt-quenching method. X-ray diffraction measurements were conducted for as-synthesized samples and after heating at elevated temperatures to investigate the structure. Extensive impedance measurements allowed us to optimize the nanocrystallization process to enhance the electrical conductivity of cathode nanomaterials. Such a procedure resulted in samples with the conductivity at room temperature ranging from $1\times {10}^{-9}$ up to $8\times {10}^{-5}$ S/cm. We carried out in situ impedance spectroscopy measurements (in an ultra-high-frequency range up to 10 GHz) and compared them with thermal events observed in differential thermal analysis studies. Full article

Alluaudite-type materials are systematically attracting more attention as prospective cathode materials for sodium-ion batteries. It has been demonstrated that optimized thermal nanocrystallization of glassy analogs of various cathode materials may lead to a significant increase in their electrical conductivity. In this paper, three alluaudite-like glasses (Na${}_2$Fe${}_3$(PO${}_4$)${}_3$—FFF, Na${}_2$VFe${}_2$(PO${}_4$)${}_3$—VFF, and Na${}_2$VFeMn(PO${}_4$)${}_3$—VFM) were synthesized and subjected to an optimized thermal nanocrystallization. This procedure resulted in nanostructured samples with increased electrical conductivity at room temperature: $5\times {10}^{-7}$ S/cm (FFF), $7\times {10}^{-5}$ S/cm (VFM), and $6\times {10}^{-4}$ S/cm (VFF). The nanocrystalline microstructure was also evidenced by ultra-high-frequency impedance spectroscopy (up to 10 GHz) and proposed electrical equivalent circuits. Prototype electrochemical cells were assembled and characterized with voltage cutoffs of 1.5 and 4.5 V. The electrochemical performance was, however, modest. The gravimetric capacity varied between the studied materials, but did not exceed 35 mAh/g. Capacity retention after ca. 100 cycles was satisfactory. Further optimization of the residual-glass-to-nanocrystallite volume ratio would be desirable. Full article

In our recent papers, it was shown that the thermal nanocrystallization of glassy analogs of selected cathode materials led to a substantial increase in electrical conductivity. The advantage of this technique is the lack of carbon additive during synthesis. In this paper, the electrochemical performance of nanocrystalline LiFePO₄ (LFP) and LiFe_0.88V_0.08PO₄ (LFVP) cathode materials was studied and compared with commercially purchased high-performance LiFePO₄ (C-LFP). The structure of the nanocrystalline materials was confirmed using X-ray diffractometry. The laboratory cells were tested at a wide variety of loads ranging from 0.1 to 3 C-rate. Their performance is discussed with reference to their microstructure and electrical conductivity. LFP exhibited a modest electrochemical performance, while the gravimetric capacity of LFVP reached ca. 100 mAh/g. This value is lower than the theoretical capacity, probably due to the residual glassy matrix in which the nanocrystallites are embedded, and thus does not play a significant role in the electrochemistry of the material. The relative capacity fade at high loads was, however, comparable to that of the commercially purchased high-performance LFP. Further optimization of the crystallites-to-matrix ratio could possibly result in further improvement of the electrochemical performance of nanocrystallized LFVP glasses. Full article

This study showed that thermal nanocrystallization of glassy analogs of LiFe${}_{1-x}$Mn${}_x$PO${}_4$ (with the addition of vanadium for improvement of glass forming properties) resulted in highly conducting materials that may be used as cathodes for Li-ion batteries. The glasses and nanomaterials were studied with differential thermal analysis, X-ray diffractometry, and impedance spectroscopy. The electrical conductivity of the nanocrystalline samples varied, depending on the composition. For $x=0.5$, it exceeded ${10}^{-3}$ S/cm at room temperature with an activation energy as low as 0.15 eV. The giant and irreversible increase in the conductivity was explained on the basis of Mott’s theory of electron hopping and a core-shell concept. Electrochemical performance of the active material with $x=0.5$ was also reported. Full article

Co-processing of radioactive effluents with coal fly ash-derived materials is recognized as a resource-saving approach for efficient stabilization/solidification of radioactive components of wastewater. In this context, the paper is focused on the hydrothermal synthesis of Sr²⁺-bearing aluminosilicate/silicate phases as analogs of a mineral-like ⁹⁰Sr waste form using hollow glass-crystalline aluminosilicate microspheres from coal fly ash (cenospheres) as a glassy source of Si and Al (SiO₂-Al₂O₃)_glass) and Sr(NO₃)₂ solutions as ⁹⁰Sr simulant wastewater. The direct conversion of cenosphere glass in the Sr(NO₃)₂-NaOH-H₂O-(SiO₂-Al₂O₃)_glass system as well as Sr²⁺ sorption on cenosphere-derived analcime (ANA) in the Sr(NO₃)₂-H₂O-ANA system were studied at 150–200 °C and autogenous pressure. The solid and liquid reaction products were characterized by SEM-EDS, PXRD, AAS and STA. In the Sr(NO₃)₂-NaOH-H₂O-(SiO₂-Al₂O₃)_glass system, the hydrothermal processing at 150–200 °C removes 99.99% of the added Sr²⁺ from the solution by forming Sr-tobermorite and Sr-plagioclase phases. In the Sr(NO₃)₂-H₂O-ANA system, Sr²⁺ sorption on analcime results in the formation of solid solutions (Na_1−nSr_n/2)AlSi₂O₆·H₂O of the Na-analcime–Sr-wairakite series. The results can be considered as a basis for the development of environmentally sustainable technology for ⁹⁰Sr removal from wastewater and immobilization in a mineral-like form by co-processing waste from coal-fired and nuclear power plants. Full article

The interaction between tissues and biomaterials (BM) has the purpose of improving and replacing anatomical parts of the human body, avoiding the occurrence of adverse reactions in the host organism. Unfortunately, the early failure of implants cannot be currently avoided, since neither a good mixture of mechanical and chemical characteristics of materials nor their biocompatibility has been yet achieved. Bioactive glasses are recognized to be a fine class of bioactive substances for good repair and replacement. BM interact with living bones through the formation of a hydroxyapatite surface layer that is analogous to bones. Bioglasses’ composition noticeably affects their biological properties, as does the synthesis method, with the best one being the versatile sol-gel technique, which includes the change of scheme from a ‘sol’ fluid into a ‘gel’. This process is widely used to prepare many materials for biomedical implants (e.g., hip and knee prostheses, heart valves, and ceramic, glassy and hybrid materials to serve as carriers for drug release). Nanoparticles prepared by the sol-gel method are interesting systems for biomedical implementations, and particularly useful for cancer therapy. This review provides many examples concerning the synthesis and characterization of the above-mentioned materials either taken from literature and from recently prepared zirconia/polyethylene glycol (PEG) hybrids, and the corresponding results are extensively discussed. Full article

Slags from the remote Mota Farun locality above Casaccia (Val Bregaglia, Swiss Alps) have been analyzed with scanning electron microscopy, X-ray powder diffraction and microfocus synchrotron X-ray diffraction to determine mineralogical composition and microstructures. Non-magnetic slag samples are largely composed of euhedral and dendritic iron-rich olivine in a glassy matrix. Locally there are zones with globular inclusions rich in bornite ((Cu₅Fe)S₄) and locally metallic copper. Some regions display dendritic pentlandite ((Fe,Ni)₉S₈). Magnetic samples are mainly composed of fayalite (Fe₂SiO₄) and wüstite (FeO), with minor magnetite (Fe₃O₄). The mineralogical composition indicates that slags were the product of copper smelting. The slag compositions and morphologies are analogous to slags described from the Oberhalbstein (Graubünden, Switzerland) and the Trentino Alps (Italy) which are attributed to metallurgical exploitations of the Late Bronze Age. While the origin of the ore could not be determined, it may be related to ore deposits of chalcopyrite in greenschists and serpentinites in the vicinity, such as Alp Tgavretga (Septimer Pass) and Val Perossa (Val Bregaglia). Full article

A new amperometric sandwich-format genosensor has been implemented on single-walled carbon nanotubes screen printed electrodes (SWCNT-SPEs) and compared in terms of performance with analogous genoassays developed using the same methodology on non-nanostructured glassy carbon platforms (GC-SPE). The working principle of the genosensors is based on the covalent immobilization of Peptide Nucleic Acid (PNA) capture probes (CP) on the electrode surface, carried out through the carboxylic functions present on SWCNT-SPEs (carboxylated SWCNT) or electrochemically induced on GC-SPEs. The sequence of the CP was complementary to a 20-mer portion of the target DNA; a second biotin-tagged PNA signalling probe (SP), with sequence complementary to a different contiguous portion of the target DNA, was used to obtain a sandwich hybrid with an Alkaline Phosphatase-streptavidin conjugate (ALP-Strp). Comparison of the responses obtained from the SWCNT-SPEs with those produced from the non-nanostructured substrates evidenced the remarkable enhancement effect given by the nanostructured electrode platforms, achieved both in terms of loading capability of PNA probes and amplification of the electron transfer phenomena exploited for the signal transduction, giving rise to more than four-fold higher sensitivity when using SWCNT-SPEs. The nanostructured substrate allowed to reach limit of detection (LOD) of 71 pM and limit of quantitation (LOQ) of 256 pM, while the corresponding values obtained with GC-SPEs were 430 pM and 1.43 nM, respectively. Full article

The well-dispersive and superparamagnetic Fe₃O₄-nanocrystals (Fe₃O₄-NCs) which could significantly enhance the anodic electrochemiluminescence (ECL) behavior of luminol, were synthesized in this study. Compared to ZnS, ZnSe, CdS and CdTe nanoparticles, the strongest anodic ECL signals were obtained at +1.6 V on the Fe₃O₄-NCs coated glassy carbon electrode. The ECL spectra revealed that the strong ECL resonance energy transfer occurred between luminol and Fe₃O₄-NCs. Furthermore, under the optimized ECL experimental conditions, such as the amount of Fe₃O₄-NCs, the concentration of luminol and the pH of supporting electrolyte, BPA exhibited a stronger distinct ECL quenching effect than its structural analogs and a highly selective and sensitive ECL sensor for the determination of bisphenol A (BPA) was developed based on the Fe₃O₄-NCs. A good linear relationship was found between the ECL intensity and the increased BPA concentration within 0.01–5.0 mg/L, with a correlation coefficient of 0.9972. The detection limit was 0.66 × 10⁻³ mg/L. Good recoveries between 96.0% and 105.0% with a relative standard deviation of less than 4.8% were obtained in real water samples. The proposed ECL sensor can be successfully employed to BPA detection in environmental aqueous samples. Full article