Search Results (140)

The detection of trace chemicals at low and ultra-low concentrations is critical for applications in environmental monitoring, medical diagnostics, food safety and other fields. Conventional detection techniques often lack the required sensitivity, specificity, or cost-effectiveness, making real-time, in situ analysis challenging. Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical tool, offering improved sensitivity through the enhancement of Raman scattering by plasmonic nanostructures. While noble metals such as Ag and Au are currently the reference choices for SERS substrates, fabrication methods should balance enhancement efficiency, reproducibility and scalability. In this study, we propose a novel approach for SERS substrate fabrication using reactive Aerosol Jet Printing (r-AJP) as an innovative additive manufacturing technique. The r-AJP process enables in-flight Ag seed reduction and nucleation of Ag nanoparticles (NPs) by mixing silver nitrate and ascorbic acid aerosols before deposition, as suggested by computational fluid dynamics (CFD) simulations. The resulting coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses, revealing the formation of nanoporous crystalline Ag agglomerates partially covered by residual matter. The as-prepared SERS substrates exhibited remarkable SERS activity, demonstrating a high enhancement factor (10⁶) for rhodamine (R6G) detection. Our findings highlight the potential of r-AJP as a scalable and cost-effective fabrication strategy for next-generation SERS sensors, paving the way for the development of a new additive manufacturing tool for noble metal material deposition. Full article

Difficult, extreme operating conditions of parabolic antennas under precipitation and sub-zero temperatures require the creation of effective heating systems. The purpose of the research is to develop a multilayer coating containing two metal-ceramic layers, epoxy composite layers, carbon fabric, and an outer layer of basalt fabric, which allows for effective heating of the antenna, and to study the properties of this coating. The multilayer coating was formed on an aluminum base that was subjected to abrasive jet processing. The first and second metal-ceramic layers, Al₂O₃ + 5% Al, which were applied by high-speed multi-chamber cumulative detonation spraying (CDS), respectively, provide maximum adhesion strength to the aluminum base and high adhesion strength to the third layer of the epoxy composite containing Al₂O₃. On this not-yet-polymerized layer of epoxy composite containing Al₂O₃, a layer of carbon fabric (impregnated with epoxy resin) was formed, which serves as a resistive heating element. On top of this carbon fabric, a layer of epoxy composite containing Cr₂O₃ and SiO₂ was applied. Next, basalt fabric was applied to this still-not-yet-polymerized layer. Then, the resulting layered coating was compacted and dried. To study this multilayer coating, X-ray analysis, light and raster scanning microscopy, and transmission electron microscopy were used. The thickness of the coating layers and microhardness were measured on transverse microsections. The adhesion strength of the metal-ceramic coating layers to the aluminum base was determined by both bending testing and peeling using the adhesive method. It was established that CDS provides the formation of metal-ceramic layers with a maximum fraction of lamellae and a microhardness of 7900–10,520 MPa. In these metal-ceramic layers, a dispersed subgrain structure, a uniform distribution of nanoparticles, and a gradient-free level of dislocation density are observed. Such a structure prevents the formation of local concentrators of internal stresses, thereby increasing the level of dispersion and substructural strengthening of the metal-ceramic layers’ material. The formation of materials with a nanostructure increases their strength and crack resistance. The effectiveness of using aluminum, chromium, and silicon oxides as nanofillers in epoxy composite layers was demonstrated. The presence of structures near the surface of these nanofillers, which differ from the properties of the epoxy matrix in the coating, was established. Such zones, specifically the outer surface layers (OSL), significantly affect the properties of the epoxy composite. The results of industrial tests showed the high performance of the multilayer coating during antenna heating. Full article

One of the key challenges in commercializing proton exchange membrane (PEM) electrolyzer technology is reducing the production costs while maintaining high efficiency and operational stability. Significant contributors to the overall cost of the device are the electrode catalysts with IrO₂ and Pt/C. Due to the high cost and limited availability of noble metals, there is growing interest in developing alternative, low-cost catalytic materials. In recent years, two-dimensional transition metal dichalcogenides (2D TMDCs), such as molybdenum disulfide (MoS₂) and rhenium disulfide (ReS₂), have attracted considerable attention due to their promising electrochemical properties for hydrogen evolution reactions (HERs). These materials exhibit unique properties, such as a high surface area or catalytic activity localized at the edges of the layered structure, which can be further enhanced through defect engineering or phase modulation. To increase the catalytically active surface area, the investigated materials were deposited on a carbon-based support—Vulcan XC-72R—selected for its high electrical conductivity and large specific surface area. This study investigated the physicochemical and electrochemical properties of six catalyst samples with varying MoS₂ and ReS₂ to carbon support ratios. Among the composites analyzed, the best sample on MoS₂ (containing the most carbon soot) and the best sample on ReS₂ (containing the least carbon soot) were selected. These were then used as cathode catalysts in an experimental PEM electrolyzer setup. The results confirmed satisfactory catalytic activity of the tested materials, indicating their potential as alternatives to conventional noble metal-based catalysts and providing a foundation for further research in this area. Full article

Inorganic nanoparticles (NPs) have been synthesised via mixing and coalescence of droplets containing precursors and entrained by gaseous streams. The droplets have been generated by ultrasonic aerosolisation of two different liquid phases, each containing the respective reagent. The as-produced NPs are trapped by mixing with a liquid phase in a Venturi nozzle, acting simultaneously as a collector and concentrator of the solid nanosized phase produced. Commercial electrically powered ultrasonic aerosolising devices have been adapted to atomise salt solutions characterised by high electrical conductivity. This process allowed the synthesis of calcium carbonate NPs with an average diameter in the range of (34–52) nm, according to the concentration of precursors in the aerosolised phases. This closed-loop method of synthesis, where neither capping agents were used nor demanding operating conditions were adopted, can represent a safe and viable eco-friendly technique for NP production free of undesirable compounds, as required for pharmaceutical preparations and theranostic uses. Full article

This study presents a novel silver nanoparticle ink formulation designed for inkjet printing applications using terpineol as an eco-friendly solvent and butylamine as a stabilizer to ensure stability, high conductivity, and compatibility with inkjet technology. Silver nanoparticles were synthesized using a modified one-pot method in the presence of highly effective stabilizers and surface modifiers such as oleic acid and oleylamine, resulting in uniform particles of less than 10 nm in size, which were then dispersed in a mixture of terpineol and butylamine. The resulting ink demonstrated exceptional stability over 85 days, maintaining optimal rheological properties for inkjet printing. The ink exhibited a perfect jetting performance. We were able to obtain silver conductive patterns reaching 81% of bulk silver conductivity. These results highlight the ink’s promise for scalable, sustainable manufacturing, combining environmental advantages with high-performance functionality. Full article

Gold nanoparticles (AuNPs) were synthesised using ultrasonic spray pyrolysis (USP) with the addition of polyvinylpyrrolidone (PVP) as a stabilising agent and subsequently dried via lyophilisation. The resulting dried AuNPs were redispersed in ethanol and homogenised to ensure uniform dispersion. This AuNP dispersion was then deposited onto a ceramic substrate—aluminum oxide (Al₂O₃)—using plasma jet printing. Comprehensive characterisation of the dispersion, AuNPs, and the resulting printed lines was performed using the following methods: inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), measurements of dispersion viscosity and printed line roughness. ICP-OES confirmed consistent gold content in the AuNP dispersion, while the SEM and EDS analyses revealed predominantly spherical AuNPs with minimal aggregation and similar size distributions. TEM, SAED, and STEM/EDS confirmed that the crystalline structure and elemental composition of the AuNPs had diverse morphologies and strong gold signals. The UV-Vis, DLS, and zeta potential measurements indicated moderate colloidal stability, and thermogravimetric analysis (TGA) verified the AuNPs dispersion’s composition. The AuNP dispersion exhibited thixotropic behaviour favourable for printing applications, while confocal microscopy confirmed smooth, uniform printed traces, with an average surface line roughness of 1.65 µm. The successful use of plasma printing with the AuNP dispersion highlights its potential for functional material applications in electronics. Full article

Zirconia ceramics (ZrO₂) have received significant attention due to their excellent mechanical properties and broad application prospects. Additive manufacturing, especially nanoparticle jetting (NPJ), offers a new approach for fabricating zirconia ceramics with complex geometries. However, the sintering process plays a crucial role in determining the final properties of these ceramics, and the effect of sintering temperature on NPJ printed zirconia ceramics remains to be fully understood. This study investigates the impact of sintering temperature on the properties of zirconia ceramics fabricated via NPJ. NPJ-printed ZrO₂ green bodies were sintered at varying temperatures, and their phase composition, microstructure, and flexural strength were analyzed. Results show that as the sintering temperature rises from 800 °C to 1450 °C, the relative density of ZrO₂ increases from 55.0% to 98.3%, and the flexural strength rises from 9.3 MPa to 356.1 MPa. The green body consists of monoclinic (m-ZrO₂) and tetragonal (t-ZrO₂) phases, with m-ZrO₂ completely transforming into t-ZrO₂ at 1000 °C. Grain size also increases with temperature. The improvement in zirconia’s flexural strength is primarily attributed to a combination of grain size and porosity. This research provides guidance for optimizing the sintering process of NPJ-printed ZrO₂ ceramics. Full article

Vaccines usually contain an adjuvant that activates innate immunity to promote the acquisition of adaptive immunity. Aluminum and lipid nanoparticles have been used for this purpose, but their accumulation or widespread circulation in the body can lead to adverse effects. In contrast, physical adjuvants, which use physical energy to transiently stress tissues, do not persist in exposed tissues or cause lasting adverse effects. Herein, we investigate the effects of intradermal injection of endotoxin-free ovalbumin (OVA) protein alone without additional adjuvants using a needle-free pyro-drive jet injector (PJI) on tumor vaccination efficacy. Intradermal injection of OVA protein alone using PJI significantly increased OVA-specific CD8⁺ T cell expansion in the lymph node, although lymph node swelling was much less than when aluminum hydroxide was used. The injection also induced OVA-specific killing activity and antibody production and showed strong CD8⁺ T cell-dependent prophylactic antitumor effects against transplanted E.G7-OVA tumors. In particular, intradermal injection of the fluorescent OVA protein significantly enhanced its uptake by XCR1⁺ dendritic cells, which have a strong ability to cross-present extracellular proteins in the skin and draining lymph nodes. In addition, the injection increased the expression of HMGB1, one of the potent danger signals whose expression has been reported to increase in response to shear stress. Thus, intradermal injection of OVA protein alone without any additional adjuvants using PJI induces potent CD8⁺ T cell-mediated antitumor immunity by enhancing its uptake into XCR1⁺ dendritic cells, which have a high cross-presentation capacity accompanied by an increased expression of shear stress-induced HMGB1. Full article

Magnetoelectric composites enable strain-mediated coupling between magnetic and electric fields, supporting applications in sensors, actuators, and tunable devices. This study presents a finite element modeling framework for simulating the direct magnetoelectric effect in core–shell and layered nanocomposites fabricated by material jetting (inkjet printing). The model incorporates nonlinear magnetostrictive behavior of cobalt ferrite nanoparticles and size-dependent piezoelectric properties of barium titanate, allowing efficient simulation of complex interfacial strain transfer. Results show a strong dependence of coupling on field orientation, particle arrangement, and interfacial geometry. Simulations of printed droplet geometries, including coffee ring droplet morphologies, reveal enhanced performance through increased surface area and directional alignment. These findings highlight the potential of material jetting for customizable, high-performance magnetoelectric devices and provide a foundation for simulation-guided design. Full article

Our research outlines a method for creating chemosensors utilizing hybrid nanostructures derived from TiO₂ ceramic nanotubes alongside conducting polymers, with embedded gold nanoparticles. The method used to create hybrid nanostructures from ceramic nanotubes and conducting polymers was drop-casting. AFM analysis highlighted an increased roughness, particularly for PANI-EB, exhibiting a significantly larger grain size exceeding 3.5 μm, with an increased inclusion of gold and uniform arrangement on the surface. The Rku parameter values being around three suggested that the layers primarily exhibited peaks rather than depressions, showing a Gaussian distribution. A chemiresistor was created by using an ink-jet printer and a multilayer metallization was achieved with commercial silver ink for printed electronics. Based on the experimental calibration curve, which exhibits adequate linearity over a wider range of H₂S concentrations in air up to 1 ppm, the detection limit was established at 0.1 ppm, a threshold appropriate for recognizing oral diseases. The sensor is a simple, affordable, and durable device designed for individual use, offering significant benefits for patients by enabling improved tracking of the syndrome’s advancement or treatment success. Full article

In hard milling, there has been a significant surge in demand for sustainable machining techniques. Research indicates that the Minimum Quantity Lubrication (MQL) method is a promising approach to achieving sustainability in milling processes due to its eco-friendly characteristics, as well as its cost-effectiveness and improved cooling efficiency compared to conventional flood cooling. This study investigates the end milling of AISI H11 die steel, utilizing a cooling system that involves a mixture of graphene nanoparticles (Gnps) and sesame oil for MQL. The experimental framework is based on a Taguchi L36 orthogonal array, with key parameters including feed rate, cutting speed, cooling condition, and air pressure. The resulting outcomes for cutting zone temperature and surface roughness were analyzed using the Taguchi Signal-to-Noise ratio and Analysis of Variance (ANOVA). Additionally, an Adaptive Neuro-Fuzzy Inference System (ANFIS) prediction model was developed to assess the impact of process parameters on cutting temperature and surface quality. The optimal cutting parameters were found to be a cutting speed of 40 m/min, a feed rate of 0.01 mm/rev, a jet pressure of 4 bar, and a nano-based MQL cooling environment. The adoption of these optimal parameters resulted in a substantial 62.5% reduction in cutting temperature and a 68.6% decrease in surface roughness. Furthermore, the ANFIS models demonstrated high accuracy, with 97.4% accuracy in predicting cutting temperature and 92.6% accuracy in predicting surface roughness, highlighting their effectiveness in providing precise forecasts for the machining process. Full article

Electrification has become increasingly common in aerospace due to climate change concerns. After successful applications in general aviation aircraft, electrification is now addressing subregional (up to 19 passengers) and regional aircraft (around 80 passengers). Megawatt-class electric motors are needed both to drive propellers and to act as high-power generators in hybrid–electric propulsion systems. Power levels for this class of aircraft require a proper design of heat management systems capable of dissipating a much higher quantity of heat than that dissipated by traditional cooling systems. The technical solution here explored is based on the addition into a diathermic base liquid of nanoparticles, which can increase (by up to 30%) the thermal conductivity of the refrigerant, also providing large surface area enhancing the heat transfer capacity of base liquids. The Italian Aerospace Research Centre (CIRA), as part of the European research initiative Optimised Electric Network Architectures and Systems for More-Electric Aircraft (ORCHESTRA), developed a thermal management system (TMS) based on impinging jets technology for a 1 MW electric motor. In this work, a numerical verification of the possibility for nanofluids to improve the heat exchange efficiency of a submerged oil impinging jets TMS designed to directly cool the inner components of a 1 MW motor is conducted. Investigations aimed to analyse two nanoparticle types (alumina and graphite) added to diathermic oil with concentrations between 1% and 5% by volume. The application of nanofluids significantly increases final thermal conductivity with respect to conventional coolants, a 60% improvement in heat transfer at a fixed mass flow rate is achieved. Electric motor maximum temperatures are approximately 10% lower than those achieved with solely diathermic oil. This result is significant as a safety margin is needed in all cases where a sudden increase in power occurs. Full article

Background: Although mRNA vaccines encapsulated in lipid nanoparticles (LNPs) have demonstrated a safety profile with minimal serious adverse events in clinical trials, there is opportunity to further reduce mRNA reactogenicity. The development of naked mRNA vaccines could improve vaccine tolerability. Naked nucleic acid delivery using the jet injection method may be a solution. Methods: In the first part of the study, the optimal conditions providing low traumatization and high expression of the model mRNA-GFP molecule in the tissues of laboratory animals were determined. Then, we used the selected protocol to immunize BALB/c mice with mRNA-RBD encoding the SARS-CoV-2 receptor-binding domain (RBD). It was demonstrated that mice vaccinated with naked mRNA-RBD developed a high level of specific antibodies with virus-neutralizing activity. The vaccine also induced a strong RBD-specific T-cell response and reduced the viral load in the lungs of the animals after infection with the SARS-CoV-2 virus. The level of immune response in mice immunized with mRNA-RBD using a spring-loaded jet injector was comparable to that in animals immunized with mRNA-RBD encapsulated in LNPs. Results: In this study, the efficacy of an inexpensive, simple, and safe method of mRNA delivery using a spring-loaded jet injector was evaluated and validated. Conclusions: Our findings suggest that the jet injection method may be a possible alternative to LNPs for delivering mRNA vaccines against SARS-CoV-2 infection. Full article

The continuous synthesis of nanoparticles (NPs) has been actively studied due to its great potential to produce NPs with reproducible and controllable physicochemical properties. Here, we achieved the high throughput production of nanostructured lipid carriers (NLCs) using a coaxial turbulent jet mixer with an added heating system. This device, designed for the crossflow of precursor solution and non-solvent, combined with the heating system, efficiently dissolves solid lipids and surfactants. We reported the flow regime according to the Reynolds number (Re). Also, we confirmed the size controllability of NLCs as dependent on both Re and lipid concentration. The optimized synthesis yields NLCs around 80 nm, ideal for targeted drug delivery by enhanced permeability and retention (EPR) effect. The coaxial turbulent jet mixer enables effective mixing, producing uniform size distribution of NLCs. The NLCs prepared using the coaxial turbulent jet mixer were smaller, more uniform, and had higher drug loading compared to the NLCs synthesized by a bulk nanoprecipitation method, showcasing its potential for advancing nanomedicine. Full article

Diesel engines employed in non-road machinery are significant contributors to nanoparticulate matters. This paper presents a novel device based on the principle of split-stream rushing to mitigate particulate matter emissions from these engines. By organizing and intensifying the airflow movement of the jet in the rushing region, the probability of collisions between nanoparticles is enhanced. This accelerates the growth and coagulation of nanoparticles, reducing the number density of fine particulate matter. This, in turn, facilitates the capture or sedimentation of particulate matter in the diesel engine exhaust aftertreatment system. The coagulation kernel function tailored for diesel engine exhaust nanoparticles is developed. Then, the particle balance equation is solved to investigate the evolution and coagulation characteristics. Afterwards, three-dimensional numerical simulations are performed to study the flow field characteristics of the split-stream rushing device and the particle evolution within it. The results show that the device achieves a maximum coagulation efficiency of 59.73%, increasing the average particle diameter from 96 nm to 121 nm. The particle number density uniformity index exceeded 0.93 in most flow regions, highlighting the effectiveness of the device in ensuring consistent particle distribution. Full article