Search Results (60)

This review highlights recent insights into the pathophysiology and therapeutic strategies for improving biocompatibility in hemodialysis. Hemodialysis activates the innate immune system, particularly the complement cascade and neutrophils, leading to acute microinflammation. Interleukin-8 (IL-8), which increases during dialysis, promotes neutrophil chemotaxis and neutrophil extracellular trap (NET) formation, triggering myeloperoxidase (MPO) release and oxidative stress. Neutrophil accumulation in atherosclerotic plaques exacerbates vascular inflammation through IL-6 upregulation. Elevated levels of IL-8, MPO, and NET-related biomarkers are associated with increased all-cause and cardiovascular mortality in dialysis patients. Strategies to mitigate these effects include the use of advanced membrane materials (e.g., AN69, vitamin E-coated, polymethyl methacrylate), novel dialysis modalities (e.g., high-volume online hemodiafiltration, cool dialysate, hydrogen-enriched dialysate), and citrate-based anticoagulation. These approaches aim to suppress complement activation, reduce oxidative stress, and limit neutrophil-induced damage. Enhancing biocompatibility is crucial for reducing cardiovascular complications and improving outcomes in dialysis patients. Suppressing the innate immune response during dialysis may become a future cornerstone in extracorporeal blood purification therapy. Full article

The removal of partially hydrogenated fats, as well as the substitution of saturated fats with healthier alternatives, has become increasingly common due to their well-established association with adverse health effects. As a result, the demand for alternative formulations in the food industry has driven the development of a promising emerging technology: oleogels. Oleogels are a semi-solid material made by trapping liquid oil within a three-dimensional network formed by structuring agents. Within this context, this study aimed to develop and characterize margarines prepared with oleogels formulated from extra virgin olive oil, coconut oil, starch, and beeswax at varying concentrations. The proposed oleogel-based formulations exhibited a high melting temperature range and lower enthalpy. Although lipid oxidation levels differed between the commercial and oleogel-based margarines, they remained within acceptable limits. A significant difference in color was observed, with the oleogel formulations imparting a slight greenish hue compared to the commercial margarine. In terms of microstructure, the commercial margarine presented smaller and more uniformly distributed water droplets. Oleogel-based margarines demonstrated technological feasibility. Considering consumers’ growing interest in food innovation and health-conscious products, olive oil-based oleogel margarines represent a promising alternative, particularly due to the nutritional benefits associated with olive oil. Full article

We used density functional theory with a hybrid functional to investigate the structure and properties of [4H]_Si (hydrogarnet) defects in α-quartz as well as the reactions of these defects with electron holes and extra hydrogen atoms and ions. The results demonstrate the depassivation mechanisms of hydrogen-passivated silicon vacancies in α-quartz, providing a detailed understanding of their stability, electronic properties, and behaviour in different charge states. While fully hydrogen passivated silicon vacancies are electrically inert, the partial removal of hydrogen atoms activates these defects as hole traps, altering the defect states and influencing the electronic properties of the material. Our calculations of the hydrogen migration mechanisms predict the low energy barriers for H⁺, H⁰, and H⁻, with the lowest barrier of 0.28 eV for neutral hydrogen migration between parallel c-channels and a similar barrier for H⁺ migration along the c-channels. The reactions of electron holes and hydrogen species with [4H]_Si defects lead to the breaking of O–H bonds and the formation of non-bridging oxygen hole centres (NBOHCs) within the Si vacancies. The calculated optical absorption energies of these centres are close to those attributed to individual NBOHCs in glass samples. These findings can be useful for understanding the role of [4H]_Si defects in bulk and nanocrystalline quartz as well as in SiO₂-based electronic devices. Full article

With the rapid development of hydrogen pipelines, their safety issues have become increasingly prominent. In order to evaluate the properties of pipeline materials under a high-pressure hydrogen environment, this study investigates the hydrogen embrittlement sensitivity of X70 welded pipe in a 10 MPa high-pressure hydrogen environment, using slow strain rate testing (SSRT) and low-cycle fatigue (LCF) analysis. The microstructure, slow tensile and fatigue fracture morphology of base metal (BM) and weld metal (WM) were characterized and analyzed by means of ultra-depth microscope, scanning electron microscope (SEM), electron backscattering diffraction (EBSD), and transmission electron microscope (TEM). Results indicate that while the high-pressure hydrogen environment has minimal impact on ultimate tensile strength (UTS) for both BM and WM, it significantly decreases reduction of area (RA) and elongation (EL), with RA reduction in WM exceeding that in BM. Under the nitrogen environment, the slow tensile fracture of X70 pipeline steel BM and WM is a typical ductile fracture, while under the high-pressure hydrogen environment, the unevenness of the slow tensile fracture increased, and a large number of microcracks appeared on the fracture surface and edges, with the fracture mode changing to ductile fracture + quasi-cleavage fracture. In addition, the high-pressure hydrogen environment reduces the fatigue life of the BM and WM of X70 pipeline steel, and the fatigue life of the WM decreases more than that of the BM as well. Compared to the nitrogen environment, the fatigue fracture specimens of BM and WM in the hydrogen environment showed quasi-cleavage fracture patterns, and the fracture area in the instantaneous fracture zone (IFZ) was significantly reduced. Compared with the BM of X70 pipeline steel, although the effective grain size of the WM is smaller, WM’s microstructure, with larger Martensite/austenite (M/A) constituents and MnS and Al-rich oxides, contributes to a heightened embrittlement sensitivity. In contrast, the second-phase precipitation of nanosized Nb, V, and Ti composite carbon-nitride in the BM acts as an effective irreversible hydrogen trap, which can significantly reduce the hydrogen embrittlement sensitivity. Full article

The encapsulation of fish oil by monoaxial electrospraying using kafirin or zein proteins as hydrophobic wall materials was investigated. Kafirin resulted in spherical fish oil-loaded nanocapsules (>50% of capsules below 1 µm), whereas zein led to fish oil-loaded nanocapsules with non-spherical morphology (>80% of capsules below 1 µm). Both hydrophobic encapsulating materials interacted with fish oil, successfully entrapping the oil within the protein matrix as indicated by Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy results. FTIR also suggested hydrogen bonding between fish oil and the proteins. Trapped radicals in the encapsulation matrix that were detected by electron paramagnetic resonance (EPR), indicated oxidation during electrospraying and storage. Results from isothermal (140 °C) differential scanning calorimetry (DSC) denoted that the encapsulation of fish oil by electrospraying using both kafirin or zein as wall materials protected fish oil from oxidation. In particular, the zein-based nanocapsules were 3.3 times more oxidatively stable than the kafirin-based nanocapsules, which correlates with the higher oil encapsulation efficiency found for zein-based capsules. Thus, this study shows that kafirin might be considered a hydrophobic wall material for the encapsulation of fish oil by electrospraying, although it prevented lipid oxidation to a lower extent when compared to zein. Full article

In this study, premature damage in cylindrical roller bearings made of 100Cr6 (SAE 52100) was investigated. For this purpose, full bearing tests were carried out using two different lubricant formulations with similar viscosities. Published research has pointed out the occurrence of tribo-chemical reactions that cause lubricant degradation and the release of hydrogen in tribo-contact. Hydrogen content measurements were conducted on tested samples, and these measurements showed dependence on the lubricant formulations. Hydrogen diffusion and trapping were identified as significant factors influencing premature damage. The measurement of trapping energies was conducted by thermal desorption spectroscopy, whereas residual stresses, which influence hydrogen diffusion and accumulation, were measured using X-ray diffraction. The measured trapping energies indicated that rolling contact caused the creation and release of hydrogen traps. Over-rolling resulted in changes in residual stress profiles in the materials, demonstrated by changes in stress gradients. These can be directly linked to subsurface hydrogen accumulation. Hence, it was possible to determine that the location of the microstructural damage (WEC) was correlated with the residual stress profiles and the subsurface von Mises stress peaks. Full article

This work deals with the effects of two individual isothermal aging experiments (450 °C/5000 h and 700 °C/2500 h) and the subsequent room-temperature electrolytic hydrogen charging of TP316H stainless steel on its Charpy V-notch (CVN) impact toughness and fracture behavior at room temperature. Microstructural analyses revealed that aging at 700 °C resulted in the abundant precipitation of intermediary phases, namely, the Cr₂₃C_6-based carbide phase and Fe₂Mo-based Laves phase, whereas aging at 450 °C resulted in much less pronounced precipitation of mostly intergranular Cr₂₃C₆-based carbides. The matrix phase of 700 °C-aged material was completely formed of austenitic solid solution with a face-centered cubic (FCC) crystal structure, whereas an additional formation of ferritic phase with a base-centered cubic (BCC) structure was detected in 450 °C-aged material. The performed microstructure observations correlated well with the obtained values of CVN impact toughness, i.e., a sharp drop in the impact toughness was observed in the material aged at 700 °C, whereas negligible property changes were observed in the material aged at 450 °C. The initial, solution-annealed (precipitation-free) TP316H material exhibited a notable hydrogen toughening effect after hydrogen charging, which has been attributed to the hydrogen-enhanced twinning-induced plasticity (TWIP) deformation mechanism of the austenitic solid solution. In contrast, both aging expositions resulted in significantly lowered hydrogen embrittlement resistance, which was likely caused by hydrogen trapping effects at the precipitate/matrix interfaces in thermally aged materials, leading to a reduced TWIP effect in the austenitic phase. Full article

This publication presents the results of combined theoretical and experimental research for the potential use of natural clinoptilolite zeolite (CLI) as an odor-adsorbing material. In this study of adsorption capacity, CLI of various granulation was used and its modifications were made by ion exchange using Sn and Fe metals to check whether the presence of metals as potential active centers does not lead to catalytic processes and may lead to enhanced absorption of odorous substances through their adsorption on the created metallic forms. Additionally, in order to increase the specific surface area, modifications were made in the form of hierarchization in an acidic environment using hydrochloric acid to also create the hydrogen form of zeolite and thus also check how the material behaves as an adsorbent. To compare the effect of CLI as a sorption material, synthetic zeolite MFI was also used—as a sodium form and after the introduction of metals (Sn, Fe). The above materials were subjected to adsorption measurements using odorous substances (including acetaldehyde, dimethylamine, pentanoic acid and octanoic acid). Based on the measurements performed, the most advantageous material that traps odorants is a natural material—clinoptilolite. Depending on the faction, its ability varies for different compounds. In the case of acetaldehyde, an effective material is clinoptilolite with a grain size of up to 2 mm. In the case of carboxylic acids, it is material after hierarchization with a fraction of 3–4 mm. In the case of theoretical calculations, information was obtained to show that metallic centers are more stable above oxygen, which is associated with the skeletal aluminum in clinoptilolite. Full article

This study compares the hydrogen embrittlement susceptibility of a Fe-30Mn-8Al-1.2C austenitic low-density steel aged at 600 °C for 0 (RX), 1 min (A1) and 60 min (A60), each exhibiting varying sizes and distributions of nano-sized κ-carbides. Slow strain rate tests were conducted to assess hydrogen embrittlement susceptibility, while thermal desorption analysis was applied to investigate hydrogen trapping behaviors. Fracture surface analysis was employed to discuss the associated failure mechanisms. The results suggest that nano-sized κ-carbides with sizes ranging from 2–4 nm play a crucial role in mitigating hydrogen embrittlement, contrasting with the exacerbating effect of coarse grain boundary κ-carbides. This highlights the significance of controlling the sizes and morphology of precipitates in designing hydrogen-resistant materials. Full article

Hydrogen production technology has triggered a research boom in order to alleviate the problems of environmental pollution and the pressure on non-renewable energy sources. The key factor of this technology is the use of an efficient photocatalyst. g-C₃N₄ is a typical semiconductor photocatalytic material that is non-toxic and environmentally friendly and does not cause any serious harm to human beings. Therefore, it can be applied to drug degradation and the photocatalytic production of H₂. Combined with ZnIn₂S₄, this semiconductor photocatalytic material, with a typical lamellar structure, has become one of the most promising catalysts for research due to its suitable bandgap structure and excellent photoelectric properties. In this study, 10% g-C₃N₄/ZnIn₂S₄ nano-heterojunction composite photocatalytic materials were successfully prepared by compounding ZnIn₂S₄ and g-C₃N₄ semiconductor materials with good visible-light-trapping ability. Under visible light irradiation, the photocatalytic activity of the composites was significantly better than that of pure g-C₃N₄ and ZnIn₂S₄. This is attributed to the formation of a heterojunction structure, which effectively inhibited the recombination of photogenerated carriers through the interfacial contact between the two semiconducting materials, and then improved the separation efficiency of the photogenerated electron–hole pairs, thus enhancing the catalytic activity. In this study, pure g-C₃N₄ and ZnIn₂S₄ were prepared using calcination and hydrothermal methods, and then, the composites were synthesized using ultrasonic and hydrothermal means. The differences in the structure, morphology, and hydrogen production performance of the materials before and after recombination were analyzed in detail using XRD, SEM, and FTIR characterization, which further verified that the 10% g-C₃N₄/ZnIn₂S₄ nano-heterojunction composites possessed excellent photocatalytic activity and stability, providing new possibilities for the optimization and application of photocatalytic hydrogen production technology. Full article

The WMoTaNbV alloy has shown promise for applications as a solid state hydrogen storage material. It absorbs significant quantities of H directly from the atmosphere, trapping it with high energy. In this work, the dynamics of the absorption of hydrogen isotopes are studied by determining the activation energy for the solubility and the solution enthalpy of H in the WMoTaNbV alloy. The activation energy was studied by heating samples in a H atmosphere at temperatures ranging from 20 °C to 400 °C and comparing the amounts of absorbed H. The solution activation energy $E_{\mathrm{A}}$ of H was determined to be $E_{\mathrm{A}}=0.22\pm 0.02$ eV (21.2 ± 1.9 kJ/mol). The performed density functional theory calculations revealed that the neighbouring host atoms strongly influenced the solution enthalpy, leading to a range of theoretical values from −0.40 eV to 0.29 eV (−38.6 kJ/mol to 28.0 kJ/mol). Full article

Photocatalytic water splitting by semiconductors is considered a promising and cost-effective method for achieving sustainable hydrogen production. In this study, a CF/SrTiO₃/In₂O₃ photocatalytic material with a double-layer core–shell structure was developed. The experimental results indicated that the produced CF/SrTiO₃/In₂O₃ composite fiber displayed superior photocatalytic hydrogen production performance, achieving a hydrogen evolution rate of approximately 320.71 μmol/g·h, which is roughly seven times higher than that of the CF/SrTiO₃ fiber alone. The enhanced photocatalytic activity of the CF/SrTiO₃/In₂O₃ fiber can be attributed to the heterojunction structure enriched with oxygen vacancies. It was found that these oxygen vacancies created defective states that served as traps for photogenerated electrons, facilitating their migration to the surface defect states and enabling the reduction of H⁺ in water to produce hydrogen. Furthermore, the synergy between the heterojunction structure and the conductivity of the carbon fiber promoted the generation and migration of photogenerated electrons, reduced the recombination of photogenerated electron–hole pairs, and ultimately improved photocatalytic hydrogen production. This study presents a new approach for designing efficient photocatalysts with surface oxygen vacancies on carbon fibers, providing new insights into the sustainable application of photocatalysts. Full article

Hydrogen embrittlement (HE) is a broadly recognized phenomenon in metallic materials. If not well understood and managed, HE may lead to catastrophic environmental failures in vessels containing hydrogen, such as pipelines and storage tanks. HE can affect the mechanical properties of materials such as ductility, toughness, and strength, mainly through the interaction between metal defects and hydrogen. Various phenomena such as hydrogen adsorption, hydrogen diffusion, and hydrogen interactions with intrinsic trapping sites like dislocations, voids, grain boundaries, and oxide/matrix interfaces are involved in this process. It is important to understand HE mechanisms to develop effective hydrogen resistant strategies. Tensile, double cantilever beam, bent beam, and fatigue tests are among the most common techniques employed to study HE. This article reviews hydrogen diffusion behavior, mechanisms, and characterization techniques. Full article

Ni-based superalloys are materials utilized in high-performance services that demand excellent corrosion resistance and mechanical properties. Its usages can include fuel storage, gas turbines, petrochemistry, and nuclear reactor components, among others. On the other hand, hydrogen (H), in contact with metallic materials, can cause a phenomenon known as hydrogen embrittlement (HE), and its study related to the superalloys is fundamental. This is related to the analysis of the solubility, diffusivity, and permeability of H and its interaction with the bulk, second-phase particles, grain boundaries, precipitates, and dislocation networks. The aim of this work was mainly to study the effect of chromium (Cr) content on H diffusivity in Ni-based superalloys; additionally, the development of predictive models using artificial intelligence. For this purpose, the permeability test was employed based on the double cell experiment proposed by Devanathan–Stachurski, obtaining the effective diffusion coefficient (D_eff), steady-state flux (J_ss), and the trap density (N_T) for the commercial and experimentally designed and manufactured Ni-based superalloys. The material was characterized with energy-dispersed X-ray spectroscopy (EDS), atomic absorption, CHNS/O chemical analysis, X-ray diffraction (XRD), brightfield optical microscopy (OM), and scanning electron microscopy (SEM). On the other hand, predictive models were developed employing artificial neural networks (ANNs) using experimental results as a database. Furthermore, the relative importance of the main parameters related to the H diffusion was calculated. The D_eff, J_ss, and N_T achieved showed relatively higher values considering those reported for Ni alloys and were found in the following orders of magnitude: [1 × 10⁻⁸, 1 × 10⁻¹¹ m²/s], [1 × 10⁻⁵, 9 × 10⁻⁷ mol/cm²s], and [7 × 10²⁵ traps/m³], respectively. Regarding the predictive models, linear correlation coefficients of 0.96 and 0.80 were reached, corresponding to the D_eff and J_ss. Due to the results obtained, it was suitable to dismiss the effect of Cr in solid solution on the H diffusion. Finally, the predictive models developed can be considered for the estimation of D_eff and J_ss as functions of the characterized features. Full article

To avoid hydrogen flaking in rail production, it is of crucial importance to understand the differences in hydrogen diffusion and trapping between different production steps. Therefore, as-cast unfinished material was compared with two finished rails, hot-rolled and head-hardened, using electron backscattered diffraction (EBSD), electrochemical permeation, and thermal desorption spectroscopy (TDS). A significant increase in dislocation density was in the head-hardened rail compared with the other material states. This leads to an effective hydrogen diffusion coefficient of 5.8 × 10⁻⁷ cm²/s which is lower by a factor of four than the diffusion coefficients examined in the other states. Thermal desorption spectroscopy analyses show a clear difference between unfinished and finished rail materials. While a peak in activation energy between 32 and 38 kJ/mol is present at all states, only as-cast unfinished material shows a second peak with an activation energy of 47 kJ/mol, which is related to microvoids. The results show that in the investigated material, the effect of increasing dislocation density has a stronger influence on the effective diffusion coefficient than the presence of a second active trapping site. Full article