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Targeted elimination of mesenchymal-like cancer cells through cyclic stretch activation of Piezo1 channels: the physical aspects
No full textThe application of cyclic stretch could represent a novel therapeutic method for fighting cancer. Research indicates that this mechanical stimulus selectively induces cell death in cancer mesenchymal-like cells while enhancing the migration and proliferation of healthy epithelial cells. Although the mechanisms have been examined through the lenses of cell signalling, gene expression, and biochemical processes, a significant gap persists in our understanding of the physical factors that drive cellular responses. This study aims to clarify the importance of physical factors, particularly the viscoelastic characteristics of the cell membrane, including actin cytoskeleton and lipid bilayer, and how their coupling affects bilayer bending and activation of the mechanosensitive Piezo1 channels in response to cyclic stretch in both epithelial and cancer cells. The bending of the bilayer surrounding Piezo1 molecules affects their conformations, which in turn influences calcium influx. This bending is contingent upon the coupling between the cell membrane and extracellular matrix. The primary factors contributing to the mechanically induced apoptosis of cancer cells are the perturbation of intracellular calcium homeostasis and disruption of focal adhesions
Nitrogen-doped carbon dots as biocompatible fluorescent agents for labelling human red blood cells
No full textEvaluating the biocompatibility of nanoparticles with blood is essential to demonstrate their biosafety, reduce potential adverse effects, and enable their application in nanomedicine. Although many studies have explored interactions between blood and nanomaterials, only limited number have specifically addressed the compatibility of nitrogen-doped carbon dots (N-CD) with red blood cells (RBC), the most abundant cells in blood, that are essential for healthy functioning of all vertebrates through their role in oxygen transport. This study investigated the biological properties of several concentrations (25, 50, 100, 200 μg/mL) of negatively charged, green fluorescent N-CD, synthesized using environmentally friendly precursors through a hydrothermal method, on healthy human RBC in vitro. Scanning electron microscopy and atomic force microscopy revealed that the treatment with N-CD, even at the highest concentration, did not significantly affect RBC morphology. Interfacial interaction between N-CD and RBC was demonstrated by photoluminescence spectroscopy, fluorescence microscopy, and synchronous fluorescence spectroscopy analysis. The treatment with N-CD at the highest concentration had no effects on the RBC osmotic fragility, slightly increased the RBC deformability, and demonstrated a noticeable protective effect on the RBC hemolysis after 24 h. Flow cytometry analysis confirmed that N-CD did not alter the RBC morphology and did not result in an increase in the production of reactive oxygen species or reactive nitrogen species, indicating that their interaction did not lead to oxidative stress induction in human RBC. These findings suggest that fluorescent N-CD are biocompatible, fluorescent RBC imaging agents and hold promise as candidates for developing novel RBC-based drug delivery systems
Thermodynamic modeling of the alkali fusionleaching process for non-standard anode slime
No full textAnode slime (AS) is an inevitable byproduct of electrolytic copper refining, one of the final
stages of Cu production. Extensive research has been conducted on AS treatment, employing
hydrometallurgical, pyrometallurgical, or hybrid methods to valorize the metals contained
within it. However, the AS generated from the electrolytic refining of non-standard copper
anodes contains notably high levels of lead (sulfates and oxides) and tin (hydrated oxide - stable
metastannic acid), along with base metals (Cu, Fe, Zn), precious metals (Au, Ag), and
technological metals (In, Ga, Ge). This variation in chemical composition presents a unique
challenge that diminishes the effectiveness of conventional treatment methods for metal
valorization. In this paper, the theoretical modeling of the alkali fusion-leaching process was
conducted to determine the optimal conditions for selective metal separation from non-standard
AS. Thermodynamic parameters of possible reactions within the defined fusion system were
analyzed using HSC Chemistry v. 9 software. The analysis encompassed Gibbs energy change
calculations and equilibrium composition as a function of temperature and additive addition
(NaOH, NaNO3). Pourbaix diagrams were generated using Hydra/Medusa software to evaluate
the phase distributions of elements during the leaching process. Thermodynamic modeling
results indicated that process temperature and oxidizing agent influence are critical for
transforming input compounds into their soluble forms, thereby affecting leaching selectivity
and metal recovery. The established reaction system and limiting reaction parameters provide
a foundation for subsequent experimental research focused on the selective recovery of tin and
precious metals
Strawberry Pomace Extract as a Sustainable Source of Bioactive Compounds for the Development of Healthcare Cotton Fabrics
No full textIn this study, bioactive compounds from strawberry pomace, a by-product of the local
fruit juice industry, were extracted using ultrasound-assisted extraction under varying
experimental conditions: extraction time (5, 25, or 45 min), ethanol concentration (20, 50,
or 80 %), and liquid-to-pomace ratio (5, 25, or 45 mL/g). The extraction process was
optimized based on the total phenolic content (TPC) using the Box-Behnken experimental
design and response surface methodology. The optimal conditions, extraction time of 37
min, ethanol concentration of 48.4%, and a liquid-to-solid ratio of 40.4:1, resulted in a
strawberry pomace extract (SPE) with a TPC of 0.80 mg GAE/mL extract and a total
flavonoid content (TFC) of 0.24 mg QE/mL extract. The obtained SPE, chitosan (CH) and
pectin (P), were utilized to functionalize 100% cotton fabric using layer-by-layer assembly.
The cotton fabric was coated with four, eight, or twelve bilayers of positively charged (CHSE) and negatively charged (P-SE) solutions. The coated fabrics were evaluated for their
antioxidant activity, the release of bioactive compounds, and the ultraviolet protection
factor (UPF). The results demonstrated that untreated cotton exhibited an antioxidant
activity of 44.9%, whereas all coated fabrics showed antioxidant activity exceeding 98.4%.
Among the three coated fabrics, the fabric coated with twelve bilayers of (CH-SE)/(P-SE)
possessed the highest bioactive compound release and a UPF factor >50, making it the
most suitable candidate for healthcare textile applications
Two-dimensional Monte Carlo simulation of source-specific risks from PM2.5-bound polycyclic aromatic hydrocarbons in indoor and outdoor school environments
No full textProbabilistic health risks in school environments from fine particulate matter (PM2.5) bound polycyclic aromatic hydrocarbons (PAHs) emitted from specific sources were evaluated. The sixteen priority PAHs were examined in PM2.5 samples collected indoors and outdoors in the heating and non-heating seasons. The average concentrations of total PAHs (ΣPAHs) bound to PM2.5 were lower indoors than outdoors, with ΣPAH concentrations being notably higher in the heating season (11.1 ± 2.3 ng/m3 indoors and 12.5 ± 4.2 ng/m3 outdoors) than in the non-heating season (8.2 ± 1.6 ng/m3 indoors and 9.9 ± 3.0 ng/m3 outdoors). Acenaphthene, benzo[b]fluoranthene, and benzo[k]fluoranthene were the most abundant PAHs. Diagnostic PAH ratios and positive matrix factorization indicated that vehicular emissions and natural gas, biomass, and coal combustion were the major sources of PAHs during the heating season, whereas traffic was the primary PAH source in the non-heating season. The average total carcinogenicity, estimated using benzo[a]pyrene (BaP) equivalents, was 0.99 ng/m3 indoors and 1.1 ng/m3 outdoors for ΣPAHs, whereas BaP and dibenz[a,h]anthracene were the highest risk contributors. Two-dimensional Monte Carlo simulation revealed the average lifetime lung cancer risk (LLCR) due to exposure to PAHs in school environments of 8.65 × 10−5 indoors and 9.63 × 10−5 outdoors. In addition, the 95th percentile of the LLCR was found to be 8.86 × 10−5 for indoors and 9.91 × 10−5 for outdoors. These results suggest that the inhalation exposure of students to PAHs bound to PM2.5 poses potential health risks but remains below the serious risk level
D1-Silver Corrosion Testing and Mitigation
No full textProblems of sulphur corrosion in recent years were frequently correlated to the corrosion of silver-plated OLTC. Unfortunately, many cases ended with failure induced by the presence of elemental sulphur (S8), ashover due to aking of deposited silver sulphide from sliding contacts. Since S8 can’t be natural constituent of re ned transformer oils, routes of oil contamination with S8 are important to be recognized. Apart of contamination by oil during regeneration with reactivating adsorbent, other possible ways of oil contamination were recognized, such as: gasket materials, cements, rubbers, reservoirs with used oils and other naphtha residues and fractions, degassing machines, used/contaminated adsorbents. The problem became ampli ed since the failure investigation records showed that minute concentrations of elemental sulphur in the oil may be enough to trigger failure. This is owing to high ratio of oil mass to the surface of silver-plated contacts that can be affected, especially in designs with in tank OLTC selector. Based on the concentration of elemental sulphur in the oil and data about amount of oil and OLTC in transformer these theoretical values can be calculated. This paper attempts to put more light on this problem, as it became spread even in modern synthetic insulating liquids. High reactivity of elemental sulphur (S8) at low temperatures was observed in laboratory tests and supported by service experiences. It was observed that deposition of silver sulphide can start from low temperatures (room and slightly higher, 40°C if S8 is present in high concentration as of 10-20 ppm). In another case, disulphides, namely dibenzyl disulphide (DBDS) was observed to frequently show suppressed corrosiveness (non-corrosive result) to silver in standardized silver corrosion tests. This is the always the case when DIN 51353 test is performed. Main problem with poor response of DIN 51353 to disulphides is low temperature (100°C) of the test and its short test duration (18h). Another silver corrosion test, ASTM D 1275-15 is performed at higher temperature (150°C) over longer duration (48h) and it has much better response to all reactive sulphur compounds. However, in signi cant number of tested oils from service, ASTM D 1275-15 was not responsive to the presence of DBDS. It was con rmed in all cases that oils did not contain metal passivator, thus excluding possible interference in the corrosion test by its presence. Another point for consideration in silver corrosion power transformer risk assessment is metal passivator incapability to protect silver surfaces against sulphur corrosion, as shown in previous publications and by service experience. This paper attempts to address these issues, response of DBDS to silver corrosion and metal passivator protective function against silver corrosion. In order to investigate conditions which will promote reaction of DBDS, modi cation of ASTM D1275-15 test was performed in conditions with oxygen content that showed the increase of DBDS reactivity to silver and is found to be in better correlation to power transformer breathing conditions. Third part of this paper deals with mitigation solutions of oils and transformers contaminated with elemental sulphur. Successful removal of S8 from mineral and synthetic ester oil was performed with success, using innovative technology. Mineral oil contaminated with high concentration of elemental sulphur was successfully treated on lab scale, including large scale oil treatment on distribution power transformer. Further on, trials of the technology on alternative liquids included treatment of synthetic ester oil contaminated with elemental sulphur on lab scale. Promising results were obtained to continue further development
Primena infracrvene termografije za testiranje dijamantskih krunica bušećih garnitura
No full textNa osnovu detaljnih laboratorijskih istraživanja reciklaže dijamantskih krunica bušećih garnitura može se zaključiti da su troškovi reciklaže: 3,2 €/kg tvrdog metala (0,9 €/kg W i 2,3 €/kg Co) odnosno četiri puta manje u odnosu na troškove proizvodnje volframa i kobalta iz ruda. Dijamanti su praktično nusproizvod (najvredniji) s obzirom na to da oni praktično ostaju nerastvorni nakon rastvaranja volframa i kobalta.
Laboratorijska istraživanja su pokazala da je optimalna tehnologija za reciklažu dijamanata iz krunica bušećih garnitura luženje u azotnoj kiselini (1:1) pri čemu Cu, Co, Ni i Fe prelaze u rastvor a volfram u obliku volfram karbida (uz koji su vezani dijamnati) ostaje nerastvoran. Volfram se rastvara luženjem sa natrijum hidroksidom i prelazi u natrijum volframat koji može da se koristi kao komercijalni proizvod ili kao polazna sirovina za dobijanje komercijalnih proizvoda od volframa kao i volframovog praha. Dijamanti se izdvajaju filtriranjem i ponovo koriste za sinterovanje dijamantskih krunica.Tehničko rešenje kategorije M85 - Novo tehničko rešenje (nije komercijalizovano
Experimental Investigation of the Stability of AunCln+m− (n = 1–5; m = 1, 3, 5, 7) Clusters by Laser Desorption/Ionization Mass Spectrometry
No full textThe stability of gold chloride clusters is an important topic in catalysis and nanomaterials, but experimental data are missing. Here, fourteen different clusters were obtained simultaneously using laser desorption/ionization mass spectrometry and were identified as AunCln+m− (n = 1–5; m = 1, 3, 5, 7) or AuCln+1−, Au2Cl2n+1−, Au3Cl2n+2−, Au4Cl2n+1− and Au5Cl2n+2−. Consequently, the effects of laser intensity on their stability were evaluated, considering differences in the AuCl unit or the number of Cl atoms. For the AunCln+1− and AunCln+3− groups, the relative intensity of the clusters decreased with each additional AuCl unit as the laser intensity increased. AunCln+5− clusters showed a different trend in relative intensities: Au3Cl8− > Au2Cl7− > Au4Cl9− > Au5Cl10−. The mononuclear AuCl4− showed the highest stability, which is consistent with their “superhalogen” character. In the Au2Cl2n+1− clusters, Au2Cl5− with Au (III)–Au(I) interaction was more stable at lower laser intensities, while Au2Cl3 with Au(I)–Au(I) bonds became more dominant at higher intensities. Among the Au3Cl2n+2−, Au4Cl2n+1− clusters, those with purely “aurophilic” interactions became increasingly stable with increasing laser intensity. These results emphasize the importance of bond type and cluster size for the stability of gold chloride clusters at different laser intensities
Decarburization and Its Effects on the Properties of Plasma-Nitrided AISI 4140 Steel: A Review
No full textDespite the surge in plasma nitriding research, few reviews thoroughly examine how surface decarburization—occurring both before and during the treatment—affects AISI 4140 and similar steel grades. This review addresses that shortfall by providing an investigation into the decarburization process and its consequences. It compiles essential findings from prior studies, demonstrating instances of decarburization in both plasma-free and plasma-containing environments. Furthermore, this analysis explores strategies to prevent decarburization and assesses its significant impact on the steel’s microstructure, hardness, corrosion resistance, and wear properties in surface and near-surface regions. Moreover, this study proposes directions for future research, emphasizing the necessity for a more detailed understanding of the decarburization mechanisms and their influence on the properties of plasma-nitrided steels
Effect of Cavitation Erosion on Material Mechanical Properties and Machine Elements Performance
No full textCavitation, a frequent phenomenon caused by the implosion of vapour or vapour-gas bubbles in fluid, commonly occurs in mechanical systems. Cavitation erosion leads to surface damage, which can reduce machine performance or even completely disrupt its operation. In addition to fluid characteristics and the geometry of machine elements, the selected material plays a significant role in cavitation erosion resistance. Previous research has concluded that cavitation erosion has a substantial impact on changes in the mechanical properties of materials. With the emergence and rapid development of additive manufacturing technologies, challenges related to the fabrication of complex geometry components have been effectively overcome. However, the impact of cavitation erosion on 3d-printed materials, particularly metals, remains largely unexplored. In addition to reviewing existing research on the influence of cavitation erosion on material properties, especially the load-bearing capacity and functionality of machine components, this study presents fundamental characteristics of cavitation erosion tested according to the ASTM G32 standard on specimens made from MS1 metal powder