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Ambient dose equivalent monitoring in the vicinity of a nuclear facility with dosemeters based on Geiger-Müller tubes
No full textArea dosemeters, which are used to estimate the effective dose by ambient dose equivalent measurements in the environment, are employed in both official and non-governmental networks. Area environment monitoring dosemeters cover a wide range of portable and/or installed detectors based on various detection mechanisms. Among others, Geiger-Müller tube detectors are most used for this purpose, more frequently so in non-governmental networks. Since these devices can often produce unreliable data, their dosimetry properties need to be thoroughly assessed. Evaluation of dosemeter performance in terms of response to influence quantity variation in laboratory conditions and on-site via a comparison and a long-term measurement campaign in the vicinity of a nuclear facility was done. A wide range of photon energies from 33 keV up to 1.25 MeV, angles of incidence up to ±90°, and dose rates in the range from near-background level fluctuations to high dose rates were examined under laboratory conditions. In addition to the on-site comparison with a reference instrument a measurement uncertainty budget was estimated for operational measurements in the environmental monitoring applications
Design of the Multi-Bioactive Graphene-Oxide/Gelatin/Alginate Scaffolds as Dual ECM-Mimetic and Specific Wound Healing Phase-Target Therapeutic Concept for Advanced Wound Healing
No full textTo develop and evaluate graphene oxide/gelatin/alginate scaffolds for advanced wound therapy capable of mimicking the native extracellular matrix (ECM) and bio-stimulating all specific phases of the wound healing process, from inflammation and proliferation to the remodeling of damaged skin tissue in three dimensions. Methods: The scaffolds were engineered as interpenetrating polymeric networks by the crosslinking reaction of gelatin in the presence of alginate and characterized by structural, morphological, mechanical, swelling properties, porosity, adhesion to the skin tissue, wettability, and in vitro simultaneous release of the active agents. Biocompatibility of the scaffolds were evaluated in vitro by MTT test on fibroblasts (MRC5 cells) and in vivo using Caenorhabditis elegans assay. Results: The scaffolds exhibited a highly porous interconnected morphology with adjustable porosity (93–96%) and mechanical strength (1.10–2.90 MPa), hydrophilic nature with high capacity to absorb physiological fluids, and stable adhesion to the skin tissue. The obtained results of MRC5 cell viability indicate that the scaffolds are safe for biomedical applications. No mortality was detected among the Caenorhabditis elegans throughout the incubation period, indicating that the scaffolds are not toxic. The results of in vitro release study of allantoin, quercetin, and caffeic acid confirm the scaffolds’ significant potential for simultaneous release. Conclusion: The graphene oxide/gelatin/alginate scaffolds are promising candidates for non-invasive, dual ECM-mimetic, and multi-target wound therapy, offering an innovative strategy to address the complexities of wound healing process
Laccase-Catalyzed Oligomerization of Esculin: Effect of Key Reaction Parameters and Evaluation of Oligoesculin Antioxidant and Skin Prebiotic Capacity
No full textEnzymatic oligomerization of flavonoids enables the synthesis of biomolecules with different structures and improved physicochemical and biological properties and can therefore broaden their application in industry. In this study, the influence of the key reaction parameters temperature, solvent, substrate, and enzyme concentrations on the synthesis of esculin oligomers was investigated. The reaction was optimized using response surface methodology (RSM) in order to obtain the highest products’ concentration and specific products’ yield (per mass of enzyme). Mass spectrometry revealed that oligomers with a degree of polymerization of up to 4 were synthesized in which dimers were the most abundant, while the NMR analysis of the esculin dimer product showed that C8-C8 link between two esculin units was formed. Maximum products’ concentration was obtained at 60 °C, in 14% (v/v) methanol, 7 mg/mL of esculin, and 54.6 U/L of laccase after 7 h, while the optimal conditions for specific products’ yield differed in the aspect of optimal laccase concentration which was 19 U/L for this output. Synthesized esculin oligomers exhibited higher iron chelating and cupric reducing antioxidant capacities and similar or even superior free radical scavenging activity compared to monomeric esculin. Moreover, the mixture of synthesized esculin oligomers has shown a promising potential to be used as a skin prebiotics, suggesting novel applications in skincare industries
Dissolving limitations: The power of DMSO activation for cellulose SEC analysis
No full textThe molar mass distribution is a crucial parameter for cellulose samples used in both research and industry, typically determined by size-exclusion chromatography (SEC) coupled with multi-angle laser light scattering and refractive index detection (MALLS-RI). While DMSO activation has been proven effective for dissolving challenging samples, such as regenerated fibers, in 9 % (w/v) DMAc/LiCl, the structural changes occurring during this activation are not yet fully understood. To address this, we analysed the effects of the DMSO activation on man-made fibers (Lyocell, Viscose, Modal) and microcrystalline cellulose over varying durations (30 min, 1 d, and 7 d), compared to conventional activation with DMAc for 7 d. The DMSO activation did not only influence the crystallinity index and hemicellulose content but also altered the dissolution behavior of regenerated cellulose fibers. Moreover, the DMSO activation step facilitated the dissolution of low-molar-mass fractions in 0.9 % (w/v) DMAc/LiCl. Importantly, the DMSO activation protocol was optimized to prevent the potential loss of low-molar-mass fractions for hemicellulose-rich samples. The altered (dn/dc)μ value was determined and applied to ensure accurate data analysis
Insight into the Morphology, Hydrophobicity and Swelling Behavior of TiO2-Reinforced Polyurethane
No full textIn this research, the structure, morphology, hydrophobicity and swelling behaviorof a polyurethane (PU) network and its composites (PUCs) were examined. PUCs weresynthesized by the incorporation of different percentages (0.5, 1 and 2 wt.%) of unmodifiedor surface-modified TiO2 nanoparticles into a PU network based on polycaprolactone,aliphatic hyperbranched polyester and isophorone diisocyanate. In order to improveinterfacial interactions, the surface of the TiO2 nanoparticles was chemically modified withlauryl gallate. The impact of the presence and content of unmodified or surface-modifiedTiO2 nanoparticles on the cross-sectional and surface morphology, swelling behavior andhydrophobicity of the PU network was assessed by different experiments. The obtainedfindings revealed that the incorporation of TiO2 nanoparticles brought a more pronouncedirregular cross-sectional and rougher surface morphology, better microphase separation,higher values of the equilibrium swelling degree in tetrahydrofuran and toluene, andaltered water contact angles compared to the neat PU. Based on the collected results, thepractical applicability of the prepared PUCs may be in the area of protective coatings
Krema obogaćena inkapsuliranim bioaktivnim komponentama ekstrahovanim iz ploda trešnje bez koštice - Cherry fusion krema
No full textS obzirom na sve širu upotrebu štetnih sastojaka u kozmetičkim formulacijama, postoji sve veća potreba za razvojem inovativnih materijala i tehnologija koje omogućavaju proizvodnju potpuno prirodnih kozmetičkih proizvoda. Ovaj rad istražuje potencijal ekstrakta ploda trešnje, bogatog polifenolima, u razvoju nove generacije kozmetičkih proizvoda, posebno kreme obogaćene inkapsuliranim bioaktivnim komponentama. Inovativna tehnologija inkapsulacije omogućava efikasnu zaštitu i kontrolisano otpuštanje polifenola, čime se značajno poboljšava stabilnost i biološka raspoloživost aktivnih sastojaka na mestu primene. Kroz tehnički pristup, pokazano je da je moguće proizvesti kozmetičku formulu koja sadrži inkapsulirane bioaktivne komponente iz ekstrakta ploda trešnje. Inkapsulati su analizirani u pogledu fizičko-hemijskih karakteristika, morfologije, stabilnosti u vodenim sistemima, veličine čestica i antioksidativnog potencijala inkapsuliranih jedinjenja. Takođe, sprovedena je HPLC analiza ekstrakta, kao i senzorni, mikrobiološki i testovi stabilnosti finalnog kozmetičkog proizvoda. Ovaj pristup ne samo da unapređuje kvalitet kozmetičkog proizvoda, već doprinosi održivosti i ekološki prihvatljivim praksama u kozmetičkoj industriji, pružajući sigurne i efikasne proizvode krajnjim korisnicima.Tehničko rešenje kategorije M8
Cavitation Erosion of Protective Coating Based on Cordierite Filler and Epoxy Matrix
No full textThe goal of this study is to investigate the surface morphology changes induced by the cavitation erosion of a coating based on cordierite with an epoxy matrix for an aluminum substrate. The literature review shows a certain lack of knowledge regarding the coating’s resistance to wearing induced by water flow, which is a highly important property of the material immersed in or in contact with water streams. The main idea behind the investigation is that such a protective coating will also improve the cavitation erosion resistance of metal substrates. The protective coatings were based on cordierite filler (88 wt.%) and epoxy resin (7 wt.%). The filler, made of a mixture of kaolin, alumina, and talc, is obtained by a sintering procedure that took place at 1350 °C. X-ray diffraction analysis and scanning electron microscopy were employed in the characterization of the produced filler. The adherence of the obtained epoxy-based protective coating and resistance to water flow were tested by the ultrasonic vibration method (i.e., cavitation erosion testing). Scanning electron microscopy was used for analysis of the coating’s morphology upon cavitation erosion. Based on the value of the cavitation erosion rate and the analyzed final surface damage, it was assessed that the investigated protective coating is resistant to cavitation erosion
Biopolymer aerogels: Structural and functional tailoring of starch/sodium alginate networks
No full textThis study explores the synthesis, structural, and functional properties of starch/sodium alginate aerogels prepared via two-step and multi-step solvent exchange methods, with and without calcium chloride (CaCl2) crosslinking. Fourier-transform infrared (FTIR) spectroscopy confirmed that both polymers were incorporated in an aerogel matrix, while Brunauer–Emmett–Teller (BET) analysis revealed that the preparation method and composition of initial polymer solution had a significant influence on surface area and porosity. Specifically, the surface area ranged from 4 to 132 m2/g, with multi-step solvent exchange producing aerogels with higher surface area and porosity. Scanning electron microscopy (SEM) showed that multi-step solvent exchange produced more homogeneous aerogel structures, while the two-step method was more effective for sodium alginate-rich aerogels. Mechanical testing revealed that crosslinked aerogels achieved a maximum stress force of up to 12 MPa, significantly higher than non-crosslinked aerogels, which showed a maximum stress of 9 MPa. Swelling studies in PBS buffer (pH 7.4) indicated that the equilibrium swelling degree (SDeq) increased with sodium alginate content, with values ranging from 330 to 656 % for sodium alginate-rich samples, due to carboxyl group dissociation, whereas non-crosslinked samples, particularly those with higher sodium alginate content, dissolve in PBS buffer. Neat starch aerogels exhibited lower swelling behavior, with SDeq values around 300 %, and were largely unaffected by the addition of the crosslinker. These findings highlight the tunable structural, mechanical, and swelling properties of starch/sodium alginate aerogels, making them promising candidates for numerous applications such as drug delivery and environmental remediation applications
Composite hydrogel with silver nanoparticles and mushroom β-glucan extract as potential wound dressing
No full textPuffballs are a group of macrofungi that produce enclosed, globose fruiting bodies. When young,
they have a solid white interior (gleba), which turns into a powdery, brown spore-bearing mass
as they mature. These fungi have been used in folk medicine worldwide, primarily as wound
dressings. Since fungal β-glucans are known to aid in wound healing, this study utilized the βglucan-enriched fraction from the pestle puffball (Lycoperdonexcipuliforme) to synthesize silver
nanoparticles (AgNPs), which were incorporated into alginate-based hydrogels for potential
wound treatment. Silver nanoparticles were synthesized via a hydrothermal method using silver
nitrate, sodium citrate, and varying concentrations of β-glucan extract as stabilizing agents: 0.4
mg/mL (S1), 0.8 mg/mL (S2), 1.6 mg/mL (S3), and 2.4 mg/mL (S4). Particle size was
approximately 30 nm for all samples, with zeta potential ranging from -22.3 to -13, increasing
with the extract concentration. A one-year stability study at room temperature showed minimal
changes in UV-VIS spectra and particle size distribution, despite relatively low zeta potential,
suggesting steric stabilization by β-glucan extract. To assess stability in physiological conditions,
samples were diluted in 0.85% NaCl solution, and size distribution and UV-VIS absorption were
monitored for seven days. Sample S4 exhibited the highest stability and was selected for further
experiments. Its antibacterial activity was tested against common wound-infecting bacteria,
Staphylococcus aureus and Pseudomonas aeruginosa, using the broth microdilution method. The
minimum inhibitory concentration (MIC) was 35 µg/mL for both strains, with minimum
bactericidal concentrations (MBC) of 120 µg/mL and 240 µg/mL, respectively. S4 was then used
to prepare an alginate-based hydrogel, and a release study was conducted to assess the product’s
potential efficacy. The hydrogel was made by mixing equal volumes of AgNP suspension and 4%
sodium alginate solution, with the addition of 4% CaCl₂ solution in a circular mold. The release
study, conducted in TRIS buffer (50 mM) with 0.85% NaCl at varying pH levels over 72 hours,
showed pH-dependent release. At pH 8.5 (similar to that of infected wounds), an effective AgNP
concentration (~35 µg/mL) was reached after ~3 hours, increasing to ~100 µg/mL after 72 hours.
These results suggest that fungal β-glucans are excellent stabilizing agents for AgNPs and that
the combination of β-glucans’ immunostimulatory and AgNPs’ antibacterial properties may have
a synergistic effect in the treatment of infected wounds. Hydrogel containing AgNPs both
prolonged, and pH-dependent release of the particles
Microbial nanocellulose as an effective lactonase immobilization matrix for enhanced wound healing
No full textChronic wounds pose a significant challenge due to bacterial biofilm infections and antibiotic resistance. Quorum-quenching enzymes like lactonases offer a promising therapeutic alternative. In this study, bacterial nanocellulose (BNC) is investigated as a biocompatible matrix for immobilization of YtnP lactonase, aiming to increase its efficacy against Pseudomonas aeruginosa. Two methods were employed: covalent cross-linking with glutaraldehyde (BNCL) and coordination with zinc ions (BNCML). Fourier transform infrared spectroscopy confirmed enzyme-matrix interactions, while differential scanning calorimetry and rheological analyses confirmed the stability of the immobilized enzyme. Both BNCL and BNCML preparations retained their activity when reused ten times and showed no significant loss of function after three months at +4 °C, while the free enzyme lost over 40 % of its initial activity. In a mouse wound model infected with P. aeruginosa, treatment with BNCL reduced the number of neutrophils, NK cells, and pro-inflammatory M1 macrophages, while increasing the number of anti-inflammatory M2 macrophages, which accelerated wound closure compared to untreated controls. In contrast, BNCML had a negative effect on healing. These results highlight BNC as a stable and biocompatible matrix for the immobilization of lactonase, making BNCL a promising infection-inhibiting alternative to conventional antimicrobial therapies for the treatment of chronic wounds