The effect of CO2 laser treatment on the surface composition and properties of a woven fabric (polyester (PET) fiber (59 wt%)/cotton (CO) fiber (31 wt%)/stainless-steel (SS) metal fibers (10 wt%)) was investigated across a range of laser intensities (19.1 × 106 to 615.0 × 106 W/m2). Elemental analysis using wavelength-dispersive X-ray fluorescence (WD-XRF) revealed that for an intensity up to 225.4 × 106 W/m2, the carbon content on the fabric surface increased while the oxygen content decreased, indicating thermally induced surface modification. Fourier transform infrared (FT-IR) spectroscopy confirmed that no new chemical bonds were formed, suggesting that the changes observed were predominantly physical in nature. High-resolution scanning electron microscopy (HR-SEM) showed progressive fiber fusion and surface smoothing with increasing laser intensity, consistent with polyester melting. Tensile testing demonstrated a significant decline in peak load and elongation at peak load with rising laser fluence, indicating mechanical embrittlement. Overall, CO2 laser treatment alters the morphology and elemental composition of the fabric surface without inducing major chemical decomposition, markedly reducing its mechanical strength.

During roof renovations, large quantities of waste BBRM (bitumen-based roofing materials) are generated, and the possibilities for recycling these materials have so far been very limited. In general, they can be crushed and mixed with asphalt to pave roads or can be burned for energy. While waste plastic materials are often recycled, the remelting process significantly degrades their durability and mechanical properties. Unlike conventional methods, our recycling process results in a material with properties that are in many ways superior to the original materials. It is durable, weather resistant, and has exceptionally high mechanical strength. This material can be used to produce various construction components, including replacing quickly degradable wooden parts in structures. The composite material demonstrates increased flexibility, enhanced tensile strength, and improved resistance to ultraviolet (UV) radiation and environmental degradation compared to standard bitumen. The process is simple and can be carried out directly at the renovation site using a portable device.

The Värska 6 well extracts mineral water from the sandstones of the Gdov aquifer at a depth of 575–595 m, with a total dissolved solids contents varying between 17 and 27 g/L. The aim of the work was to study 1) the market for nasal/throat sprays in Estonia; 2) the opinions of pharmacy employees and customers; 3) the composition and sterility of the mineral water; and 4) the possibility of developing a nasal/throat spray based on local mineral water. A total of 17 nasal sprays were marketed in Estonia in 2022, of which 12 were for nasal use only and 5 were nasal/throat sprays. Most (70%) were solutions with isotonic salt concentrations made from dissolved or undiluted sterilised seawater or ocean water. The indications for their use are diverse, ranging from daily nasal hygiene to the relief of colds. Värska 6 water has a high salinity (20 g/L), a Na–Cl chemical type, and – compared to ocean water and nasal sprays made from ocean water – is enriched in lithophile elements (Fe, Mn, Li, Sr, and Ba) characteristic of deep groundwater. The hypertonic Värska 6 mineral water is bacteriologically clean, and the temporal stability test confirmed that the mineral water does not promote bacterial growth but inhibits it. A new product was developed – the mineral water-based hypertonic nasal/throat spray Tsilk.

Anion exchange membrane fuel cells (AEMFCs) are sustainable and clean electrochemical energy conversion devices due to their high feasibility of employing platinum-free catalysts for oxygen reduction reaction (ORR). Herein, we selected vinylferrocene and vinylimidazole polymer composite with their conductive and coordination networks anticipated for their diverse electrochemical applications. The prepared catalyst materials possess highly abundant ORR-active centers and favourable physico-chemical properties like high specific surface area, pore size distribution, defects and surface chemical states, which are confirmed by X-ray diffraction, Raman spectroscopy, N-2 physisorption, X-ray photoelectron spectroscopy and scanning transmission electron microscopy. The catalyst materials are assessed through optimization of different ratios of vinylferrocene and vinylimidazole along with zinc nitrate treatment to attain the prominent textural properties for efficient electrocatalytic ORR activity in 0.1 M KOH electrolyte and the half-wave potential is 0.80-0.85 V vs. RHE, which is comparable to that of the Pt/C benchmark. Amongst, FerNC-T2 shows higher ORR activity than other prepared catalysts. This is accredited to the highly active Fe-Nx sites and hierarchical porous structure of the electrocatalyst. This work made a significant impact in developing efficient electrocatalysts for AEMFC cathodes owing to the excellent electrochemical stability in RDE study and high-power density in an AEMFC (344 mW cm(-2)).

Plant resource sharing mediated by mycorrhizal fungi has been a subject of recent debate, largely owing to the limitations of previously used isotopic tracking methods. Although CdSe/ZnS quantum dots (QDs) have been successfully used for in situ tracking of essential nutrients in plant-fungal systems, the Cd-containing QDs, due to the intrinsic toxic nature of Cd, are not a viable system for larger-scale in situ studies. We synthesized amino acid-based carbon quantum dots (CQDs; average hydrodynamic size 6 ± 3 nm, zeta potential −19 ± 12 mV) and compared their toxicity and uptake with commercial CdSe/ZnS QDs that we conjugated with the amino acid cysteine (Cys) (average hydrodynamic size 308 ± 150 nm, zeta potential −65 ± 4 mV) using yeast Saccharomyces cerevisiae as a proxy for mycorrhizal fungi. We showed that the CQDs readily entered yeast cells and were non-toxic up to 100 mg/L. While the Cys-conjugated CdSe/ZnS QDs were also not toxic to yeast cells up to 100 mg/L, they were not taken up into the cells but remained on the cell surfaces. These findings suggest that CQDs may be a suitable tool for molecular tracking in fungi (incl. mychorrhizal fungi) due to their ability to enter fungal cells.

Pyrolysis is a promising way to reuse of waste tires. However, the carbon black generated in the process is often contaminated with various pyrolysis products. This study aims to recycle low-quality recycled carbon black (rCB) from waste tire pyrolysis, addressing the challenges posed by organic residues (up to 5 wt% bituminous substances, 112.2 mg/kg PAH). This causes the agglomeration of particles and decreases the active specific surface area. Cavitational vortex milling (both wet and dry) emerges as a promising method to valorize contaminated rCB, allowing for a significant reduction in the concentration of contaminants. This novel method allows for the generation of hydrophilic and hydrophobic black pigments. In parallel experiments, low-quality rCB is incorporated into solid biofuel to enhance its calorific value. The addition of 10 wt% rCB) to peat residues significantly elevates the calorific value from 14.5 MJ/kg to 21.0 MJ/kg. However, this improvement is accompanied by notable increases in CO2 and SO2 emissions. This dual effect underscores the necessity of considering environmental consequences when utilizing recycled carbon black as a supplement to solid biofuels. The findings provide valuable insights into the potential of cavitational vortex milling for carbon black valorization and highlight the trade-offs associated with enhancing biofuel properties through the addition of rCB.

HydroThermal Liquefaction (HTL) is a process that involves the reaction of polymer compounds such as cellulose, lignin, synthetic plastics, etc. with near-critical or supercritical water to form low molecular weight liquid compounds, similar to natural oil which is believed to have formed over millions of years. Compared to other biomass recovery methods such as pyrolysis or anaerobic digestion, HTL is highly efficient with an energy efficiency of up to 90%, while the others have an efficiency of only around 30%. However, traditional HTL requires extremely high temperatures (250–450 °C) and pressures (100–350 bar), which are challenging to achieve using large-scale industrial equipment. This study proposes the use of ultrasonic cavitation to induce a supercritical state in water locally, rather than throughout the entire reactor, making it possible to perform HTL reactions using inexpensive and simple devices. The study demonstrates the successful conversion of pure cellulose to low molecular weight liquid compounds using potassium hydroxide as a catalyst.

Functionalization of nanocarbon materials with heteroatoms is of paramount interest as doping of carbon with electron withdrawing groups results in change of electrochemical properties of the potential catalyst. Adding fluorine, as the most electronegative element into the doping process next to boron is expected to have significant effect on the design of novel nanocarbon-based electrocatalysts. In this paper boron and fluorine co-doped reduced graphene oxide/few-walled carbon nanotube (BF-rGO/FWCNT) catalysts are synthesized via simple and low-cost direct pyrolysis method using boron trifluoride diethyl etherate (BTDE). Composition analysis confirmed that boron and fluorine have been grafted onto the carbon support. Rotating disk electrode (RDE) measurements revealed that BF-rGO/FWCNT has remarkable electrocatalytic activity toward the oxygen reduction reaction (ORR) both in alkaline and acid media. The onset potential of the best BF-rGO/FWCNT catalyst was 50 mV more positive in alkaline and 600 mV more positive in acidic media compared with un-doped rGO/FWCNT. The half-wave potential was 100 mV more positive in alkaline media and 700 mV more positive in acidic media in comparison with un-doped rGO/FWCNT. Boron and fluorine co-doped carbon catalyst was synthesized via simple and low-cost direct pyrolysis method. Various physical characterization methods revealed the incorporation of boron and fluorine into the carbon matrix. Rotating disc electrode method showed the enhanced electrocatalytic activity of the co-doped catalyst compared with the undoped material. image

Abstract Silicone is often used in environments where water repellency is an advantage. Contact with water promotes the adhesion of microorganisms and biofilm formation. Depending on the application, this may increase the possibility of food poisoning and infections, the material's degrading appearance, and the likelihood of manufacturing defects. The prevention of microbial adhesion and biofilm formation is also essential for silicone-based elastomeric foams, which are used in direct contact with human bodies but are often difficult to clean. In this study, the microbial attachment in and the retention from the pores of silicone foams of different compositions is described and compared to those of commonly used polyurethane foams. The growth of the gram-negative Escherichia coli in the pores and their leaching during wash cycles is characterised by bacterial growth/inhibition, adhesion assay, and SEM imaging. The structural and surface properties of the materials are compared. Despite using common antibacterial additives, we have found that non-soluble particles stay isolated in the silicone elastomer layer and, therefore, do not possess antibacterial activity. Water-soluble tannic acid dissolves into the medium and seems to aid in inhibiting planktonic bacterial growth, indicating that tannic acid is available on the surface of the SIFs to some extent.

Water, alcohols, diols, and glycerol are low-cost blowing agents that can be used to create the desired silicone foam structures. Although their combined use can be beneficial, it remains unclear how it affects the physical properties of the resulting materials. We conducted a comparative study of these hydroxyl-bearing blowing agents in fumed silica- and mica-filled polymer composite systems for simultaneous blowing and crosslinking to obtain a low-density, uniform porosity and superior mechanical properties. The foams were optimized for a uniform open-pore structure with densities ranging from 75 to 150 kg‧m−3. Varying the diol chain length (Cn) from one to seven carbons can alter the foam density and structure, thereby enhancing the foam tensile strength while maintaining a low density. Replacing 10 mol% of water with 1,4-butanediol decreased the density by 26%, while increasing the specific strength by 5%. By combining glycerol and water blowing, the resulting foams exhibited a 30% lower apparent density than their water-blown analogs. The results further showed that Cn > 4 alkane chain diols had an odd–even effect on the apparent density and cell wall thickness. All foamable compositions had viscosities of approximately 7000 cSt and curing times below 2 min, allowing for quick dispensing and sufficient time for the foam to cure in semi-industrial volumes.

Atomic Layer Deposition (ALD) has been investigated for the possible protection of various materials against atomic oxygen (ATOX) at ESTEC Materials and Electrical Components Laboratory facility. ALD is a conformal coating process, that can be used to apply ultra-thin films of metal oxides on various materials, that may have a sophisticated three-dimensional shape, such as the internal and external components of satellites. The challenge with metal oxides on soft and/or flexible surfaces arises from the brittle nature of these ceramic films if their thickness exceeds 30 nm. Different substrates, including silicon, Printed Circuitry Board (PCB), polyimide, and Carbon Fibre Reinforced Polymers (CFRP) were coated by ALD with 20 nm thick metal oxide films at 125 °C, then exposed to ATOX and characterized by photographing, reflectance measurement and scanning electron microscopy (SEM). The studies showed good performance of protective films prepared by ALD on polymer substrates, which suggests that the nanometer-scale coatings can improve the lifetime of these materials at low Earth orbit, where they are inevitably exposed to ATOX. In contrast, the uncoated substrates suffered near-surface damage after exposure to ATOX, which resulted in microscopic features on their surface that were visible in SEM. Damage caused by ATOX to the uncoated substrates was also visible in photographs and observable in reflectance studies. In the latter case, the changes in the reflectance spectrum were caused by the change of surface morphology and/or chemical and elemental composition due to corrosion by ATOX.

Silicone is often used in environments where water repellency is an advantage. Contact with water promotes the adhesion of microorganisms and biofilm formation. Depending on the application, this may increase the possibility of food poisoning and infections, the material's degrading appearance, and the likelihood of manufacturing defects. The prevention of microbial adhesion and biofilm formation is also essential for silicone-based elastomeric foams, which are used in direct contact with human bodies but are often difficult to clean. In this study, the microbial attachment in and the retention from the pores of silicone foams of different compositions is described and compared to those of commonly used polyurethane foams. The growth of the gram-negative Escherichia coli in the pores and their leaching during wash cycles is characterised by bacterial growth/inhibition, adhesion assay, and SEM imaging. The structural and surface properties of the materials are compared. Despite using common antibacterial additives, we have found that non-soluble particles stay isolated in the silicone elastomer layer, thus affecting surface microroughness. Water-soluble tannic acid dissolves into the medium and seems to aid in inhibiting planktonic bacterial growth, with a clear indication of the availability of tannic acid on the surfaces of SIFs.

The present study considers TiC-derived carbon (CDC) and its partially oxidized derivative (ox-red-CDC) as potential electrode materials for pH-neutral aqueous electrolytes. The CDC was converted to ox-red-CDC by a modified Hummers’ method involving back-reduction with hydrogen at 800 °C. Oxidation degraded the graphitic CDC structures, as shown by X-ray diffraction analysis, while scanning electron microscopy confirmed the exfoliation of graphene layers on the oxidized carbon surface. The changes in the surface chemistry of the carbon materials were studied by infrared, X-ray photoelectron, and energy-dispersive X-ray spectroscopy. The gas adsorption analysis showed a slight decrease in the volume of the subnanometer-sized pores during oxidation/reduction of CDC. To elucidate the relationships between the structure and electrochemical properties of carbon materials, cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy measurements were performed in 1 M Na2SO4 using 2- and 3-electrode test cells. The highest capacitance of 163 F g−1 was demonstrated by pristine TiC-derived CDC in a symmetric 2-electrode cell. The asymmetric cell, which contained ox-red-CDC as an anode and pristine CDC as a cathode, had a slightly lower capacitance but an excellent cycling lifetime (specific capacitance increased by 7% after 5000 cycles). Temporary repolarization of 2-electrode cells during cycling improved both capacitance and power characteristics.

Transition metal-containing nitrogen-doped carbon catalysts for the electrochemical oxygen reduction reaction (ORR) were prepared from inexpensive biomass - rapeseed press cake; cobalt and/or iron salts and dicyandiamide were employed as metal and nitrogen sources. After acid treatment, the catalysts showed excellent electrocatalytic ORR activity in rotating disk electrode experiments in 0.1 M KOH solution, comparable to that of Pt/C (20 wt%) catalyst; good tolerance to methanol and high stability in short-time tests. The bimetallic catalyst displayed moderate performance as cathode material in anion exchange membrane fuel cell (AEMFC) test, by reaching the peak power density of 131 mW cm-2.

The kinetics of the platinum-catalyzed dehydrocondensation reaction for five different mono-alcohols and water is studied in order to identify the ones with the highest effectiveness in releasing gaseous H-2 from the Si-H groups of poly(methylhydrosiloxane) (PMHS). Our results show that the most common logic rules of alcohol reactivity do not apply in such reactions and that a set of aspects need to be considered together to understand or predict the outcome and the possible applications. In dehydrocondensation of PMHS, the use of Lamoreaux' catalyst may be considered to be a cost-effective alternative, a novel approach in characterizing catalyzed reaction kinetics under mild conditions. To the best of our knowledge, it is the first article describing the use of Lamoreaux' in this approach.

Shungite is used in water filters that remove Escherichia coli from water.The mechanism and spectrum of the antibacterial activity of shungite are not precisely known.In this study, shungite and its dried water extract were characterized by means of X-ray diffraction, X-ray fluorescence and iodometry.The dried residue of the water extract of shungite was relatively poor in carbon (28.1% in the rock vs 0.5% in the residue), silica (23.9% in the rock vs 0.3% in the residue) and potassium (1.14% vs 0.05%), but rich in sulfur (1.6% vs 21.6%) and some metals, including iron (1.4% vs 10%), aluminum (2.1% vs 5%) and nickel (0.02% vs 1.14%).The survival of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, Streptococcus uberis and Saccharomyces cerevisiae in shungite water was measured.Escherichia coli, Pseudomonas aeruginosa and Streptococcus uberis did not survive for 24 hours in 3:7 shungite water extract, while Staphylococcus aureus, Candida albicans and Saccharomyces cerevisiae survived as well as in distilled water.Neutralization of pH did not abolish the bactericidal effect.However, in the presence of nutrients, shungite water did not show bacteriostatic or bactericidal effects.

Even though enehydrazide moiety is present in many pharmaceuticals, there is currently no straightforward method available for preparing cyclic enehydrazides, which could be valuable building blocks in anticancer research. Herein, we report how electronic effects and ring size influence the direction and yield of Ru catalytic carbon–carbon double bond isomerization in heterocyclic enehydrazines. Having the knowledge of how variation of these properties affects the equilibrium between double bond isomers enables us to control the outcome when preparing different cyclic enehydrazides. Six enehydrazide heterocycles and five enehydrazine heterocycles were synthesized and characterized with the current method. In addition, cytotoxicity evaluation of the synthesized compounds showed that several heterocycles produced in this study could be used in developing anticancer drugs.

We investigated the distribution of the Nd3+ impurity centers over five Ca2+ positions in the beta-Ca-3(PO4)(2) lattice (space group R3c) using low-temperature site-selective laser spectroscopy and fluorescence kinetics measured by double spectral selection in combination with the results of periodic density functional theory (DFT) calculations. Site-selective fluorescence excitation spectra of the Nd3+ ion were measured by fine tuning the laser wavelength in the spectral band of the I-4(9/2)(1) -> (4)G(5/2)(1,2) transitions and by fluorescence detection in the spectral band of the F-4(3/2)(1) -> I-4(9/2)(1,2) transitions. The kinetics of nonradiatiative energy transfer from the F-4(3/2)(1) crystal field (CF) level was used to probe the local structure of Nd3+ sites. Theoretical modelling of the replacement of Ca2+ ions by Nd3+ ions with different charge compensation schemes was carried out. In the context of heterovalent substitution, hydrothermal synthesis conditions, and charge-balance mechanisms, two structural models of substitution have been proposed and thoroughly studied: substitution by a single Nd3+ ion accompanied by a trapped hydroxyl group, and substitution with a pair of Nd3+ ions. Numerical modeling of possible substitution scenarios calculated for a large number of combinations of cation-exchange sites in the lattice was carried out. The results obtained were classified according to the parameters of the accommodation of impurities and the energies of defect formation. The most favorable configurations of the distribution of impurity Nd3+ cations in the beta-Ca-3(PO4)(2) lattice were predicted. By combining the "energy transfer probe" analysis and the results of the structural modeling, a relationship was found between the local geometry and the spectral and kinetic properties of luminescence of the Nd3+ optical centers. This allowed us to accurately determine the local structural geometries of eight experimentally detected the Nd3+ optical centers among the various possibilities in the distribution of the dopant ions over five cationic positions in beta-Ca-3(PO4)(2). Six optical centers represent different types of Nd3+ - Nd3+ pairs, the formation of which is energetically favorable for charge compensation according to the 3Ca(2+) -> 2Nd(3+) + square scheme, when one calcium position remains vacant. Two optical centers are single centers of the Nd3+ ion in which the charge is compensated by negatively charged hydroxyl ions intercalated during hydrothermal synthesis according to the scheme Ca2+ -> Nd3+ + OH-. It was assumed that these pairs are located in several structural cavities free of PO4 tetrahedra. (C) 2021 Elsevier B.V. All rights reserved.

Fluorescent nanoparticles (FNPs) have been widely used in chemistry and medicine for decades, but their employment in biology is relatively recent. Past reviews on FNPs have focused on chemical, physical or medical uses, making the extrapolation to biological applications difficult. In biology, FNPs have largely been used for biosensing and molecular tracking. However, concerns over toxicity in early types of FNPs, such as cadmium-containing quantum dots (QDs), may have prevented wide adoption. Recent developments, especially in non-Cd-containing FNPs, have alleviated toxicity problems, facilitating the use of FNPs for addressing ecological, physiological and molecule-level processes in biological research. Standardised protocols from synthesis to application and interdisciplinary approaches are critical for establishing FNPs in the biologists' tool kit. Here, we present an introduction to FNPs, summarise their use in biological applications, and discuss technical issues such as data reliability and biocompatibility. We assess whether biological research can benefit from FNPs and suggest ways in which FNPs can be applied to answer questions in biology. We conclude that FNPs have a great potential for studying various biological processes, especially tracking, sensing and imaging in physiology and ecology.

In this study, two compounds (melamine phosphate and hexachlorocyclotriphosphazene) were used as nitrogen and phosphorus precursors to dope silicon carbide-derived carbon (SiCDC) with nitrogen and phosphorus moieties. The successful heteroatom doping was confirmed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy/energy-dispersive X-ray (SEM-EDX) analysis. The resulting N,P-doped SiCDC exhibited high oxygen reduction reaction (ORR) performance in alkaline conditions in terms of onset and half-wave potential, slightly surpassing the ORR activity of solely N-doped SiCDC. Since N2 physisorption showed that the porosity parameters and specific surface area of N,P-doped SiCDC (in which melamine phosphate was used as a N and P precursor) were rather similar to that of N-doped SiCDC, the improvement in the ORR activity of N,P-doped SiCDC could be attributed to the new ORR-active sites produced by the introduction of nitrogen and phosphorus moieties into the SiCDC.