Search Results (361)

Greenly synthesised Ni-doped Ag nanoparticles utilising Caralluma umbellata root extracts, and an investigation into their optical properties, biological properties, and characterisation, is the focus of the study. Characterisation was performed using FTIR analysis, UV-Vis, X-ray diffraction, and field emission scanning electron microscopy. The synthesis of Ni-doped Ag nanoparticles was confirmed through UV-Vis spectroscopy, revealing a peak at 396 nm and a band gap energy of 3.24 eV. XRD analysis revealed a face-centred cubic structure with a crystallite size of 55.22 nm (as-prepared) and 18.56 nm (annealed at 200 °C). Reduction and capping were demonstrated by FTIR, as evidenced by the presence of phytochemicals. The Ag NPs demonstrated potent antibacterial activity against both Gram-positive and Gram-negative bacteria, with a minimal inhibitory concentration of 1.25 μg/mL observed against Streptococcus mutans. Their vigorous anti-oxidant activity, as well as in vitro anti-diabetic potential through alpha-amylase and alpha-glucosidase inhibition, also proves suitable for biomedical applications. Full article

Fly ash–based geopolymers have emerged as a promising alternative to ordinary Portland cement, offering high mechanical strength and reduced environmental footprint. However, they are often limited by significant shrinkage and strength degradation when subjected to elevated temperatures. To enhance their thermomechanical performance and thermal stability, this study investigates the effects of mix proportioning parameters, alkali activator type, and thermal shock on performance deterioration. Compressive strength was evaluated for sodium- and potassium-activated fly ash geopolymer composites as a function of alkaline activator (AA) ratios, both under ambient curing and after exposure to the ISO 834 standard fire curve for 1 and 2 h. Volume change, mass loss, and density variation were analysed to interpret mechanical behaviour and relate it to structural transformations, while XRF, XRD, SEM, and particle size distribution were employed for material characterisation. Results indicate that rapid temperature changes, whether from thermal shock or high fire-heating rates, induced notable additional thermal degradation. Sodium activation achieved the highest compressive strength retention of 145% at one hour of firing, while potassium activation showed superior thermal stability with delayed densification, reaching 154% strength retention at two hours. Furthermore, SiO₂/M₂O ratio exerted the strongest influence on both mechanical and thermomechanical performance. Overall, the findings highlight that the activator type, SiO₂/M₂O ratio, and rapid temperature changes collectively exert strong control over the thermomechanical and thermophysical response of fly ash geopolymers at elevated temperatures. Full article

Background/Objectives: Chromium (III) oxide nanoparticles possess unique chemical properties, making them increasingly valuable in pharmaceutical applications, which had been neglected until the last few years. However, their use requires stable dispersion and surface functionalization to ensure their biocompatibility. This study aimed to synthesise, characterise, and determine the biocompatibility and antioxidant properties of chromium oxide nanoparticles coated with a natural, plant-derived stabilising agent: chia seed mucilage extract. Methods: The synthesised nanoparticles were characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared (FTIR) spectroscopy, and laser diffraction scattering particle size analysis (LD-PSA). Biological and biochemical assessments were conducted by the DPPH and FRAP assays to quantify antioxidant scavenging abilities and the Artemia salina lethality test for preliminary biocompatibility evaluation. Results: XRD, FTIR, and EDS confirmed the successful synthesis of pure chromium oxide NPs (CrNPs) and their effective coating by the chia mucilage (CM) extract. SEM analysis determined that a 4:1 mass ratio (CrNPs to CM) produced the most consistent morphology and narrowest size distribution, yielding spherical particles approximately 50 nm in diameter. LD-PSA confirmed the coating and identified a hydrodynamic diameter of approximately 0.110 µm. Biological and biochemical assays showed high antioxidant activity, with over 80% free radical scavenging at concentrations of 250 μg/mL and 50 μg/mL. Furthermore, the biocompatibility assessment showed survival rates above 90% across all tested concentrations. Conclusions: The findings confirm that chia seed mucilage extract can serve as an effective, biocompatible coating agent for chromium (III) oxide nanoparticles. The resulting functionalized particles exhibit exquisite biocompatibility and significant antioxidant potential, supporting their further development for pharmaceutical use. Full article

In the context of global energy demands, the efficient demulsification of highly stable heavy crude oil emulsions remains a critical challenge. This study systematically investigated the demulsification mechanisms of two demulsifiers (P1# and P2#) through multi-dimensional characterisation and performance evaluation. The results indicated that asphaltenes and resins can strengthen the oil–water interfacial film and stabilise the emulsion due to their unique structural properties. FTIR and ¹HNMR analyses showed that both demulsifiers contained polar groups and alkyl chains; however, P1# exhibited higher viscosity and lower surface tension, which favored its rapid adsorption at the interface. Demulsification tests at 60 °C demonstrated that P1# achieved superior efficiency (92.44% demulsification efficiency (DE) in 120 min versus 82.31% for P2#), attributable to its enhanced ability to displace asphaltene/resin at the oil-water interface. Turbiscan stability analysis and microscopic observations confirmed that P1#-treated emulsions underwent faster droplet coalescence and significant interfacial film disruption. Mechanistic studies indicated that the demulsifiers competitively adsorb at the interface, thereby weakening film cohesion through steric hindrance and charge redistribution. XRD and FTIR analyses suggested that interactions between the demulsifier and the asphaltene/resin increased interlayer spacing and reduced crystallinity. Zeta potential and interfacial tension measurements further highlighted P1#’s ability to neutralize negative charges (from −14.52 mV to +8.3 mV) and reduce the IFT (from 28.5 mN/m to 12.1 mN/m), thereby promoting droplet aggregation. This study helps elucidate the mechanism of emulsion phase transition induced by demulsifiers and provides theoretical support for improving the demulsification efficiency of crude oil emulsions. 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

In order to address the urgent demand for high-performance materials in the field of automotive lightweighting, there is a need for solutions to the interface instability and performance degradation of traditional reinforcing phases (e.g., SiC, CNT) at elevated temperatures. The present study prepared BNNTs/Al composites via the stirred casting method for automotive connecting rods. The microstructure, interface characteristics, phase evolution, and high-temperature wettability were systematically characterised using a range of analytical techniques, including SEM, TEM, XRD, and DSC. A study was conducted to assess the mechanical properties of the composites in comparison to those of conventional 40Cr steel. This investigation enabled an evaluation of the material’s comprehensive performance for use in automotive connecting rods. The study successfully achieved uniform dispersion of BNNTs within the aluminium matrix, forming tightly bonded, semi-coherent interfaces such as Al/AlN and Al/AlB₂. It was found that complete wetting was achieved at 675 °C, with interface reactions generating AlN and AlB₂ phases that significantly enhanced performance. The prepared connecting rod demonstrates a specific strength that significantly exceeds that of 40Cr steel. The experimental investigation conducted in a controlled setting yielded notable outcomes. The empirical evidence demonstrated a 6.5% enhancement in braking performance and a 5.8% reduction in fuel consumption. Through the optimisation of interface design and process control, the BNNTs/Al composite achieves a balanced compromise between high strength, low density, and excellent thermal stability. The material’s potential for use in lightweight automotive connecting rods is significant, offering a novel approach to the eco-friendly manufacturing of related components. Full article

Background: Polyols are widely used as tablet diluents due to their high solubility, favourable taste, and ability to form robust tablets. Thus, commercially available polyols, such as mannitol and isomalt, can be considered for the preparation of low-drug-dose formulations with a high polyol load. Methods/Results: This study investigated spray-dried mannitol (Mannogem^® XL Opal SD and Pearlitol^® 200 SD) and fluid-bed granulated isomalt (galenIQ™ 720 and galenIQ™ 721) at magnesium stearate levels of 0.5 and 3.0 wt.% and consolidation pressures of 100 and 300 MPa. During the tableting of 100 consecutive tablets, materials displayed different ejection force profiles: galenIQ™ 720 and galenIQ™ 721 demonstrated low and stable ejection pressures; Mannogem^® displayed a lubricant- and compaction pressure-dependent profile, whereas Pearlitol^® produced the highest ejection forces, particularly at 0.5 wt.% magnesium stearate. To elucidate these differences, the used materials were characterised in terms of SEM imaging, moisture content, surface area and porosity analysis, particle size distribution, pXRD, and densification kinetics. Using a compaction simulator, key parameters including pressure–displacement profiles, mean yield pressure, and strain rate sensitivity of the unlubricated materials were experimentally determined, while pressure transmission, residual die-wall pressure, and friction coefficient were computed. Conclusions: The study concluded that variations in tableting properties were primarily governed by moisture content and, for mannitol grades, by manufacturing method-dependent differences in particle microstructure. These insights provide guidance for the rational selection of polyol excipients and appropriate lubrication levels in direct compression tablet formulations. Full article

The structural modification of tyre-derived activated carbon (TDAC) after chemical activation is not sufficiently recognised yet, especially regarding its crystallinity and porosity. This study examined the development of the crystal structure of TDAC by X-ray diffraction (XRD) analysis, concentrating on critical parameters like interplanar distance (d(002)), crystallite size (Lc), and crystalline percentage. Mixed tyres were pyrolysed at 550 °C to produce char and then chemically activated with KOH at different ratios and temperatures, thereafter undergoing structural characterisation. The results indicate that TDAC is mostly non-graphitizing, maintaining a disordered turbostratic structure even after activation. The widening of the (002) XRD peak and the lack of distinct (hkl) diffraction peaks validate its amorphous characteristics. Higher activation levels lead to an expanded surface area with decreasing crystallite size, signifying a shift towards higher disorder. This research examined the relationship among activation factors, porosity, and structural alterations, emphasising the compromise between crystallinity and surface area. Full article

Iminophosphine ligands find extensive applications in homogeneous catalysis; however, their potential antitumor activity is currently being explored. Including biologically active moieties, such as aminoalcohols, could enhance this activity further. Therefore, we have synthesised a novel series of Pd(II) and Pt(II) iminophosphine complexes incorporating aminoalcohols as biologically active moieties to explore the potential of enhancing this activity. The series of Pd(II) complexes includes complexes 2a, 2f, and 2h, which were previously reported by our research group as catalysts in Suzuki–Miyaura cross-coupling reaction in aqueous media. Besides their complete characterisation, some structures have been unequivocally corroborated by single-crystal X-ray diffraction (SC-XRD). To evaluate the cytotoxic potential of the complexes, a preliminary in vitro study was conducted on different cancerous cell lines, including using COS-7 cells as a healthy cell line. Notably, complexes 2e, 2f, and 3b exhibited selectivity towards human chronic myelogenous leukaemia (K562), demonstrating IC₅₀ values of 7.73 ± 1.4 µM, 8.53 ± 1.9 µM, and 8.83 ± 1.5 µM, respectively. Remarkably, the selectivity of these complexes surpassed that of cisplatin. Furthermore, in silico analysis indicated a higher binding energy of these complexes to DNA when compared to cisplatin. Full article

Evaluation of characteristics and flocculation mechanisms of microbial flocculants facilitates the identification of potential applications and informs the fine-tuning of operational conditions for maximum activity. Therefore, this study aimed to characterise and optimise the operational conditions of bioflocculants produced from Klebsiella pneumoniae and Meyerozyma guilliermondii for potent wastewater treatment. Scanning electron microscopy, X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR) were employed to assess the surface morphology, crystalline structure, thermal stability, and functional group composition of the bioflocculants. Their cytotoxicity was assessed using the tetrazolium bromide-based assay against human colorectal adenocarcinoma (CaCO-2) cell lines. Flocculation efficiencies and mechanisms were determined using Jar and zeta potential assays, respectively. The bioflocculant from K. pneumoniae (Kp1) revealed a fibrous morphology, whereas that from M. guilliermondii (Mg1) displayed a granular structure. FTIR spectra revealed hydroxyl, amine, and alkene groups as key functional groups, while TGA analysis indicated that Kp1 was thermally unstable, contrary to Mg1, which exhibited good thermal stability. Bioflocculants Kp1 and Mg1 exhibited COD removal of 90.86% and 93.12% and turbidity reductions of 92.65% and 92.74%, respectively. Zeta potential analysis revealed that bioflocculant Kp1 primarily flocculated through charge neutralisation, while Mg1 employed a bridging mechanism. These bioflocculants illustrated strong potential to treat wastewater. However, the observed cytotoxic effect at increased concentrations warrants cautious handling and application in lower doses. Full article

This study systematically investigates the effect of hydrogen flow rate (100, 200, 300, and 400 sccm) on the properties of DC53 steel during a 4 h plasma nitriding process conducted at 400 °C in an asymmetric bipolar pulsed reactor. A comprehensive characterisation approach was employed. X-ray diffraction (XRD) was used to identify the phase composition, revealing the formation of a compound layer consisting of ε-Fe_2–3N (identified by its (100), (101), and (102) planes) and γ’-Fe₄N (identified by its (220) plane). Mechanical properties were assessed using Vickers microhardness for surface measurements and nanoindentation for depth profiling. Glow discharge optical emission spectroscopy (GD-OES) provided elemental depth analysis, while a ball-on-disk tribometer evaluated the tribological performance. The optimal treatment was achieved at a hydrogen flow rate of 200 sccm. This condition yielded a peak surface hardness of 1121.5 ± 69.2 HV_0.2. GD-OES analysis directly correlated this mechanical enhancement to a high surface nitrogen content of approximately 8.5% and an effective diffusion depth of about 50 µm. Full article

The present experimental study was set up to examine the use of waste seashells (ground to powder form) to replace cement partially and as a filler material in concrete. Two distinct particle size ranges of seashell powder were adopted based on their intended function: 63–125 micron particles are used as a filler to enhance packing density, and 0–63 micron particles are used as a cement replacement to improve reactivity. Four concrete mixes, including a control mix, were designed, with ground seashell powder used to replace cement, both as a filler replacing 15% of the cement and additionally as finer seashell powder replacing 0, 15, and 30% of cement (labelled S0F15, S15F15, and S30F15, respectively). The seashells’ chemical, physical, and mineralogical properties were characterised using particle size analysis through sieving, X-ray diffraction (XRD), Scanning Electron microscopy (SEM), and pH test methods. Furthermore, the fresh properties of concrete, such as initial and final setting time, were studied. The hardened seashell-based concrete was subjected to direct compressive strength, bulk density, and modulus of elasticity analysis. The results showed that the 28-day compressive strength of concrete with seashells was moderately reduced by nearly 25% compared to the control mix. In the case of modulus of elasticity, the reductions were about 5%, 7% and 13% for mixes S0F15, S15F15 and S30F15, respectively, compared to the control mix CM. Finally, the carbon emission from concrete with 15% and 30% seashell powder content as cement replacement (plus 15% cement replaced with the powder acting as a filler in both cases) resulted in a notably lower carbon emission of 250 and 212 kg CO₂ e/m³, respectively, compared to the control mix, with a reduction of approximately 24%. This is a sizable reduction in Global Warming Potential (GWP) value. Therefore, the study concluded that the investigated seashell powder in concrete could benefit an eco-friendly environment and conservation of natural resources. Full article

Nanostructured TiO₂/Cu coatings were deposited on Ti6Al4V alloy by a two-step glow-discharge sputtering process and evaluated for their structural, electrochemical, and biological properties. Dual-acid etching produced microroughened substrates before TiO₂ layer deposition, followed by surface Cu sputtering with varied deposition times. Characterisation by AFM, OM, SEM/EDS, and XRD confirmed the formation of TiO₂ with Cu/Cu₂O-containing hybrid coatings with good adhesion to the substrate. Increasing Cu deposition enhanced surface hydrophobicity and copper ion release. EIS measurements proved that the coatings retained stable protective behaviour in simulated body fluid (SBF). Antibacterial tests against Escherichia coli showed up to 98% improved efficacy compared to bare Ti6Al4V, confirming the strong antimicrobial role of copper. However, MG63 osteoblast-like cells exhibited reduced viability even after pre-immersion in PBS, suggesting that cytotoxicity was associated not only with excess Cu ion release but also with direct interaction between cells and surface Cu nanostructures. Overall, the results indicate that TiO₂/Cu coatings provide excellent antimicrobial activity, good protection and strong adhesion, but their limited biocompatibility highlights the need for fine-tuned copper incorporation in future biomedical implant applications. Full article

This study presents the synthesis and characterisation of cellulose long chain fatty acid ester films using a novel distillable ionic liquid (IL), 5-methyl-1,5,7-triaza-bicyclo-[4.3.0] non-6-enium acetate [mTBNH][OAc] in combination with DMSO as a cosolvent. The cellulose esters cellulose diacetate (CDA), cellulose laurate (CL), and cellulose palmitate (CP) were fabricated through an evaporation-induced phase separation method (EIPS) and dried under two conditions: conventional oven drying (RO) and vacuum oven drying (VO). The influence of drying conditions on the structural, thermal, and surface properties of the films was evaluated using XRD, TGA, SEM, AFM, and contact angle measurement techniques. XRD confirmed an amorphous structure in all films, with no significant effect on the drying conditions. TGA revealed consistent thermal degradation profiles across all samples, with ester group decomposition accruing between 140 and 250 °C and main cellulose backbone degradation near 350 °C. The SEM cross-section showed a uniform film, devoid of cavities and layered structures. AFM analysis demonstrated that VO-dried films had smoother surfaces compared to RO-dried films, correlating with increased contact angles and enhanced hydrophobicity. A strong inverse relationship between surface roughness and hydrophobicity was observed, particularly in VO-dried samples, although this was not statistically significant due to data variability. Overall, the drying method had minimal impact on the internal structure and thermal stability; it significantly influenced surface morphology and wettability. Full article

Gold (Au) and silver (Ag) nanoparticles (NPs) are used for drug transport and plant protection due to their insoluble nature and unique properties. To produce health-friendly NPs, toxic solvents should be replaced with plant-based synthesis. Plants, such as alfalfa (Medicago sativa L.), release biomolecules that reduce metal ions and form nanoclusters without free radicals, showing anti-inflammatory and antioxidant properties. In this study, callus cultures of two M. sativa genotypes, ‘Kometa’ and ‘La Bella Campagnola’, were exposed to two precursors (AgNO₃ and HAuCl₄) for 24 and 48 h to assess the feasibility of biological NP synthesis. Spectrophotometry showed significant (p ≤ 0.05) changes in light absorbance compared with the control. Dynamic light scattering and zeta potential measurements indicated a change in the composition of the liquid compared with the control. To improve image quality and obtain more accurate data, transmission electron microscopy (TEM) analysis was repeated, confirming the presence of quasi-spherical nanoparticles with diameters in the range of 5–25 nm for both AuNPs and AgNPs in the callus culture extracts of both genotypes. Nanoparticle Tracking Analysis demonstrated that the AgNPs and AuNPs from both genotypes displayed polydisperse size distributions, with a mean particle size ranging from 220 to 243 nm. Elemental analysis provided clear evidence that Ag and Au were present only in treated samples, confirming effective NP biosynthesis and excluding contamination. X-ray diffraction (XRD) analysis was performed to characterise the crystalline structure; however, due to the very small particle size (5–25 nm), no clear diffraction patterns could be obtained, as nanocrystals below ~20–30 nm typically produce signals below the detection limit of standard XRD instrumentation. The novelty of this research is the cost-effective, rapid biosynthesis of quasi-spherical AuNPs and AgNPs with diverse sizes and enhanced properties, making them more eco-friendly, less toxic, and suitable for antibacterial and anticancer studies. Full article