Search Results (368)

Despite metals currently being widely used in orthopedic surgery, their mechanical properties significantly differ from the surrounding tissues and organs, causing low biocompatibility. Biodegradable, non-toxic, and non-immunogenic materials seem to be more convenient for clinical implementation. Our research was aimed at the construction of a polylactide screw covered with collagen, nanohydroxyapatite, and polylactide, with a variant including silver nanowires for antibacterial properties, as well as the analysis of their physico-chemical and biological properties. Adherent human osteosarcoma cells (2T line) were shown to grow on the porous surface layers. A cytotoxicity assay using WST1 revealed the non-toxic nature of the coatings and showed an increase in cell adhesion and proliferation. Safety and efficacy were also evaluated in vivo with the coated screws implanted into the metatarsal bones of minipigs. Histological analysis at 29 and 58 days post-screw-implantation revealed that the coated samples accelerated bone tissue regeneration compared to uncoated controls. This was evidenced by a higher bone-to-granulation tissue ratio, reduced inflammatory cell counts, and increased osteoblast/osteoclast activity at the early stage during the initial days after implantation. The results confirm that the developed bioactive coatings enhance biocompatibility and osteointegration. Full article

This study developed a natural rubber (NR) composite reinforced with surface-modified pineapple leaf fibres (PALFs) and hemp fibres (HFs) using a layer-by-layer (sandwich-like) fabrication method. The objectives were to increase the utilisation of the natural fibres as reinforcing agents and to investigate the impact of silane fibre surface modification on the properties of the sandwich composites. Fibre surface characterisation was performed using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) to confirm the presence of functional groups from silane and cellulose. The wettability and adhesion properties of the modified fibres were also evaluated. The mechanical properties were investigated via single-fibre tensile tests. Composites with 50 phr silane-treated PALF showed the best compromise in terms of interface adhesion (48.3 mJ/m²) and tensile strength (6 MPa). This result was also supported by scanning electron microscopy (SEM), which revealed the absence of voids between the fibres and the NR matrix. Furthermore, dynamic mechanical analysis showed that the PALF composite treated with silane at 50 phr exhibited the best viscoelastic behaviour. NR composites with 50 phr silane-treated PALF have mechanical properties suitable for potential applications in engineering products. Full article

This study presents a robust methodology for analyzing 3D roughness parameters to characterize sandblasted surfaces, identifying the most relevant descriptors for process optimization. Sandblasting with irregularly shaped corundum particles is performed using five grit sizes (25, 50, 90, 125, and 250 µm) and three pressure levels (2, 3, and 4 bar). The resulting surfaces are characterized through eight 3D roughness parameters: Sa, Spc, Sal, Sfd, Sdq, Sdr, Spd, and Str. A linear model of the form Q = a + b.D + d.D.P, where Q represents the roughness parameter, D is the average grit size, and P is the sandblasting pressure, is employed. For Spd, a nonlinear model, Spd = (a + b.D + d.D.P)², yields a significantly improved determination coefficient, demonstrating the model’s enhanced ability to capture the complexity of the Spd parameter. The double-bootstrap analysis validates the statistical significance of all models, providing confidence intervals for each parameter. This approach emphasizes the importance of advanced 3D roughness descriptors for accurately analyzing surface textures in sandblasting processes, offering a reliable framework for surface characterization and industrial optimization. Full article

Textile dye effluents, particularly cationic dyes, pose a major environmental challenge, demanding efficient and sustainable adsorbent materials to remove harmful synthetic dyes. In this study, a reference thiourea–formaldehyde (TU/FA) composite and a series of thiourea–poly(acrylic acid)–formaldehyde (TU/PAA/FA) composites were synthesized and systematically characterized. The composites were prepared by varying the volume of poly(acrylic acid) PAA (from 1 to 7.5 mL) to assess how PAA incorporation influences morphology, crystallinity, surface chemistry, charge, and thermal stability. Analytical techniques including SEM, XRD, FT-IR, particle size distribution, zeta potential, and TGA/DTG revealed that increasing PAA content induced more porous and amorphous microstructures, intensified carbonyl absorption, reduced particle size (optimal at 2.5–5 mL PAA), and shifted the zeta potential from near-neutral to highly negative values (−37 to −41 mV). From TU/PAA/FA composite analysis, it was depicted that the TU/PAA-5/FA material has the better characteristics as a potential cationic dye absorbent. Thus, the adsorption performance of this composite toward crystal violet dye was subsequently investigated and compared to the reference material thiourea–formaldehyde (TU/FA). The TU/PAA-5/FA material exhibited the highest capacity (145 mg/g), nearly twice that of TU/FA (74 mg/g), due to the higher density of carboxylic groups facilitating electrostatic attraction. Adsorption was pH-dependent, maximized at pH 6, and decreased with temperature, confirming an exothermic process. Kinetic data followed a pseudo-second-order model (R² = 0.99), implying chemisorption as the rate-limiting step, while Langmuir isotherms (R² > 0.97) indicated monolayer adsorption. Thermodynamic analysis (ΔH° < 0, ΔS° < 0, ΔG° > 0) further supported an exothermic, non-spontaneous mechanism. Overall, the TU/PAA-5/FA composite combines enhanced structural stability with high adsorption efficiency, highlighting its potential as a promising, low-cost material for the removal of cationic dyes from textile effluents. Full article

Easy and rapid preparations of magnetic Co- and Pd-containing mesoporous carbons (IM1, IM2 and DM) from green phenolic resins, amphiphilic templates and metallic salts via two synthetic routes are reported. Catalysts IM1 and IM2 are prepared via an indirect method involving two steps, i.e., the preparation of Co-containing mesoporous carbons with different Co contents (2.5 and 12.5%) and the further introduction of Pd (2.3%) via impregnation using a solution of a Pd salt and a process of thermal reduction. The mesoporous carbon obtained contains two distinct crystalline metallic phases, i.e., Co particles of 5.0 nm (IM1) and Pd nanoparticles of ~1.3 nm (IM1), while the increase in Co content triggers higher Co particle sizes of 23 nm and Pd particle sizes of 1.3 and 6.8 nm (IM2). Differently, the catalyst DM is prepared via direct synthesis, in one step, including all precursors and both metal salts. This results in Pd₅₀-Co₅₀ nanoalloys of 6.5 nm uniformly dispersed in the carbon matrix. The reactivity and reusability of catalysts IM1, IM2 and DM were then ascertained in organic synthesis for hydrogenations of nitroarenes and enones. It turned out that no reactions were observed in the presence of the catalyst DM due to the presence of Co in Pd₅₀-Co₅₀, which deactivates the catalytic activity of Pd. Gratifyingly, catalysts IM1 and IM2 were very efficient for mild hydrogenations of both nitroarenes and enones using only 5 mequiv. of supported Pd in EtOH at room temperature. The smaller Pd particle sizes (1.3 nm) and the high surface-to-volume area are probably responsible for the high reactivity observed. Catalysts IM1 and IM2 can be recovered by application of an external magnetic field. However, a more efficient magnetic recovery of catalyst IM2 compared to IM1 was observed due to its higher Co content. Catalyst IM2 can be successfully reused at least seven times without a loss of efficiency. Finally, almost-Pd-free products can be obtained directly after reaction without any purification step, since the Pd leaching is very low (<0.1% of the initial amount), thus decreasing waste and increasing the reaction’s efficiency. Full article

This study deals with the physical, chemical, and thermal properties of William banana peduncle fibers in order to consider the possibility of using these new fibers in textile applications. The samples were collected in Cameroon, in the Littoral region, Njombe Penja district (agri-food industry). The fibers were extracted by three methods, including Water Retting (WR), Dew Retting (DR), and Mechanical Extraction (ME). The various resulting fibers were characterized by X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Fourier-Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM), respectively. The FTIR analysis confirmed the lignocellulosic structure of the fibers and revealed that the three extraction methods had not affected the chemical nature of the fibers. The extraction methods also had no significant impact on density and moisture content. Scanning electron microscopy showed bands of fibers bundles on all samples. Thermogravimetric analysis (TGA) showed that the fibers extracted were thermally stable at 82 °C. X-ray diffraction (XRD) analysis showed crystallinity levels ranging from 58.24% for (WR), 54.83% for (DR), and 69.53% for (ME). The results obtained on the chemical composition show that the extracted fibers consist mainly of 71.8%, 73.6%, and 74.8% cellulose for WR, DR, and ME, respectively, making them suitable for textile applications. Full article

Eleven novel asymmetric pyrimidine derivatives were synthesized. The pyrimidine core was functionalized with a coumarin chromophore and a pro-mesogenic fragment bearing either chiral or linear alkyl chains of variable length and substitution patterns. The thermal properties were investigated using polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering, revealing that only selected derivatives exhibited liquid crystalline phases with ordered columnar or smectic organizations. Linear and nonlinear optical properties were characterized by UV–Vis absorption, fluorescence spectroscopy, two-photon absorption, and second-harmonic generation. Optical responses were found to be highly sensitive to the substitution pattern: derivatives functionalized at the 4 and 3,4,5 positions exhibited enhanced 2PA cross-sections and pronounced SHG signals, whereas variations in alkyl chain length exerted only a minor influence. Notably, compounds forming highly ordered non-centrosymmetric mesophases produced robust SHG-active thin films. Importantly, strong SHG responses were obtained without the need for a chiral center, as the inherent asymmetry of the linear alkyl chain derivatives was sufficient to drive self-organization into non-centrosymmetric materials. These results demonstrate that asymmetric pyrimidine-based architectures combining π-conjugation and controlled supramolecular organization are promising candidates for nonlinear optical applications such as photonic devices, multiphoton imaging, and optical data storage. Full article

High-pressure intrusion of water and LiCl aqueous solutions at different concentrations in hydrophobic STT-type zeosil was studied for possible applications in absorption and storage of mechanical energy. The water is intruded at a pressure of 35 MPa and remains trapped in the pores after pressure release, which corresponds to bumper behavior with total energy absorption. The use of LiCl solution leads to a change in system behavior, regardless of the concentration investigated (10, 15, or 20 M). Its intrusion is mainly reversible, but a small part of the intruded liquid remains in the pores after the first intrusion–extrusion cycle, which corresponds to a mixed behavior of bumper and shock absorber. The intrusion pressure rises strongly with an increase in salt concentration and reaches 227 MPa for a LiCl 20 M solution; the stored energy of 27 J/g can be achieved. The characterization of STT-type zeosil before and after intrusion–extrusion tests by structural and physicochemical methods shows that silanol defects are formed both under the intrusion of water and LiCl solutions. The relationship between zeosil structure and intrusion–extrusion characteristics is discussed by comparing the results obtained with those of other structural types of zeosils. Full article

The photoinitiation properties of two porphyrins were evaluated for the free-radical photopolymerization (FRP) of a bio-based acrylated monomer, i.e., soybean oil acrylate (SOA). Their combination with various co-initiators, such as a tertiary amine as electron donor (MDEA), an iodonium salt as electron acceptor (Iod), as well as two biosourced co-initiators used as H-donors (cysteamine and N-acetylcysteine), makes them highly efficient photoinitiating systems for FRP under visible light irradiation. Electron paramagnetic resonance spin trapping (EPR ST) demonstrated the formation of highly reactive radical species, and fluorescence and laser flash photolysis highlighted the chemical pathways followed by the porphyrin-based systems under light irradiation. High acrylate conversions up to 96% were obtained with these different systems at different irradiation wavelengths (LEDs@385 nm, 405 nm, 455 nm, and 530 nm), in laminate or under air. The final crosslinked and bio-based porphyrin-based materials were used for the full photo-oxidation in water of an azo-dye (acid red 14) and under UV irradiation. These materials have been involved in three successive depollution cycles without any reduction in their efficiency. Full article

Collaborative filtering (CF) continues to be a fundamental approach in recommendation systems for providing users with personalized suggestions. However, such kind of recommender systems are prone to performance issues when faced with noisy, inconsistent, or deliberately manipulated user ratings. Although Generative Adversarial Networks (GANs) offer promising solutions to capture complex user-item interactions in these CF situations, many existing GAN-based methods assume uniform reliability across all ratings, reducing their effectiveness under uncertain conditions. To overcome this challenge, this paper presents DST-AttentiveGAN to introduce a confidence-aware adversarial framework specifically designed to denoise inconsistent ratings in collaborative filtering scenarios. The proposed approach employs Dempster-Shafer Theory (DST) to compute confidence scores by aggregating diverse behavioral indicators, such as item popularity, user activity, and rating variance. These scores guide both components of the GAN architecture in which the generator incorporates a cross-attention mechanism to highlight trustworthy features, while the discriminator uses DST-based confidence to evaluate the credibility of input ratings. Training is carried out using a stabilized Wasserstein GAN objective that promotes both robustness and convergence efficiency. Experimental results in three benchmark data sets show that DST-AttentiveGAN consistently surpasses conventional GAN-based models, delivering more accurate and reliable recommendations under conditions of uncertainty. Full article

This review provides an overview of existing accident prevention methods by monitoring the persons’ physiological state, observing movements, and physiological parameters. Firstly, different physiological parameters monitoring systems are introduced. Secondly, various systems dealing with position recognition on pressure sensing mats are presented. We conduct an in-depth literature search and quantitative analysis of papers published in this area and focus independently of the application (drivers, office and wheelchair users, etc.). Quantitative information about the number of subjects, investigated scenarios, sensor types, machine learning usage, and laboratory vs. real-world works is extracted. In posture recognition, most works recognize at least forward, backward, left and right movements on a seat. The remaining works use the pressure sensing mat for bedridden people. In physiological parameters measurement, most works detect the heart rate and often also add respiration rate recognition. Machine learning algorithms are used in most cases and are taking on an ever-greater importance for classification and regression problems. Although all solutions use different techniques, returning satisfactory results, none of them try to detect small movements, which can pose challenges in determining the optimal sensor topology and sampling frequency required to detect fine movements. For physiological measurements, there are lots of challenges to overcome in noisy environments, notably the detection of heart rate, blood pressure, and respiratory rate at very low signal-to-noise levels. Full article

A series of functionalized calix[4]arenes were prepared that contain mono- and bis-(alkoxy)imidazolium groups that are linked to the lower rim of a t-butylcalix[4]arene framework. These molecules have potential as anion-complexation reagents and as precursors to N-heterocyclic carbene complexes that are attached to a calixarene framework. They were prepared by the preliminary reaction α,ω-dibromoalkanes with the parent t-butylcalix[4]arene to give bis-ω-bromoalkoxy groups that are connected to the calix[4]arene framework in the 25- and 27-positions. The reaction of the bis-substituted calixarenes with TiCl₄ led to the removal of one bromoalkoxy group to give mono-substituted derivatives. Both the mono- and bis-functionalized calixarenes were reacted with N-substituted imidazoles to give a series of mono- or bis-imidazolium salts with the imidazolium group tethered to the calix[4]arene via O–(CH₂)_n– linkages (n = 2, 4, or 6). Unexpected bis-calix[4]arene products, in which the calixarenes are linked together via bridging organic groups, were obtained in some of these reactions. One bridge consists of two calixarenes linked together via two –C₂H₄– groups while the other had a –O–C₄H₈–imidazolium-C₄H₈–O– linker tethering the two calix[4]arenes together. Both these species were characterized by single crystal X-ray diffraction studies. The structures both had significant disorder but, nevertheless, the data do establish their structures. That the imidazolium-substituted calix[4]arene cations are precursors to N-heterocyclic carbene complexes of nickel was demonstrated by the reaction of a mono-imidazolium-substituted calix[4]arene with nickelocene to give the fully characterized N-heterocyclic carbene nickel complex linked to the calix[4]arene group. Full article

Treating brain cancer remains challenging due to the blood–brain barrier (BBB) and the systemic toxicity of chemotherapy. This study focuses on developing human serum albumin (HSA) nanoparticles modified with low-molecular-weight protamine (LMWP) to improve crossing the BBB and enable targeted delivery of curcumin and temozolomide (TMZ). Nanoparticle stability was enhanced by crosslinking with aldehyde groups from oxidized gellan (OG). The successful attachment of LMWP to HSA at the thiol group of Cys34 was confirmed through FT-IR and ¹H-NMR analyses. Most self-assembled nanoparticles were smaller than 200 nm in diameter. Curcumin showed higher encapsulation efficiency than TMZ. In vitro drug release was pH-dependent: curcumin released more at pH 7.4, while TMZ release was better at pH 4. Higher crosslinking degrees reduced drug release. Cytotoxicity assays on V79-4 (normal) and C6 (glioma) cell lines showed increased apoptosis and significantly lower IC₅₀ values for co-encapsulated formulations, indicating a synergistic effect. Curcumin’s antioxidant activity was maintained and protected from UV degradation by the polymer matrix. The parallel artificial membrane permeability assay (PAMPA) confirmed that the functionalized formulations with co-encapsulated drugs could cross the BBB. Hemocompatibility studies indicated a favorable profile for intravenous use. Full article

Background: Body composition assessment is important in professional football as a measure of overall adaptation of the athlete to the training demand and calorie intake. However, it is operator-dependent, relying on subject positioning and the focus angle of the X-rays. In addition, the usual appendicular lean mass index (ALMI) does not include the pelvitrochanteric muscles, which are often implicated in athlete injuries. Methods: Three independent operators compared the reproducibility of dual-energy X-ray absorptiometry (DEXA) including pelvi-trochanteric muscle mass in twenty professional football players, using the standard and a new method. Results: Mean age, weight, and height of the footballers were 25.9 ± 4.9 years, 79.4 ± 9.4 kg, and 1.83 ± 0.09 m. Using the standard method, the ALMI was 9.28 ± 0.62, 9.20 ± 0.65, and 9.13 ± 0.64 kg/m² for the first, second and third operator, respectively. When including the pelvi-trochanteric muscles, the ALMI values were 11.90 ± 0.66, 11.84 ± 0.63, and 11.83 ± 0.65 kg/m² for the three operators. The difference between the two methods was significant (p < 0.001). The mean inter-operator difference was similar regardless of the method used (0.099 ± 0.06 kg/m²). The intraclass correlation coefficients (ICC) (A,1) were 0.949 [0.881; 0.979] for the standard method and 0.977 [0.951; 0.990] for the new method. The ICC (C,1) was 0.960 [0.918; 0.983] for the standard method and 0.979 [0.957; 0.991] for the new method. Conclusions: Thus, both new and conventional methods showed excellent reproducibility. However, reproducibility and inter-operator variability were better with the adjustment of the new scan lines. Moreover, the inclusion of a larger gluteal and adductors muscle mass was easy to achieve, providing additional information that could potentially be useful for early diagnosis and/or prevention of future muscular injuries in elite athletes. Full article