Mean Diameter Of Nanoparticles Research Articles

Control of Intermolecular Interactions toward the Production of Free-Standing Interfacial Polydopamine Films.

Aggregation of the polydopamine (PDA) molecular building blocks at the air/water interface leads to obtaining large surface nanometric-thin films. This mechanism follows two possible pathways, namely, covalent or non-covalent self-assembly, which result in a different degree of structure order and, consequently, different structural properties. Control of this mechanism could be vital for applications that require true self-support PDA free-standing films, for example, electrochemical sensing or membrane technology. Here, we are considering the impact of boric acid (BA) and Cu2+ ions on the mentioned mechanism exclusively for the free-standing films from the air/water interface. We have employed and refined our own spectroscopic reflectometry method to achieve an exceptionally high real-time control over the thickness growth. It turned out that BA and Cu2+ ions significantly impact the film growth process. Reduction of the nanoparticles size and their number was examined via UV-vis spectroscopy and transmission electron microscopy, showing a colossal reduction in the mean diameter of nanoparticles in the case of BA and a moderate reduction in the case of Cu2+. This modification is leading to significant enhancement of the process efficiency through moderation of the topological properties of the films, as revealed by atomic force microscopy. Next, applying infrared, Raman, and X-ray photoelectron spectroscopy, we presented small amounts of metal (B or Cu) in the final structure of PDA and simultaneously their vital role in the oxidation mechanism and cross-linking through covalent or non-covalent bonds. Therefore, we revealed the possibility of synthesizing films via the expected self-assembly mechanism which has hitherto been out of control. Moreover, modification of mechanical properties toward exceptionally elastic films through the BA-assisted synthesis pathway was shown by achieving Young's modulus value up to 24.1 ± 5.6 and 18.3 ± 6.4 GPa, using nanoindentation and Brillouin light scattering, respectively.

Investigation of Various Cooling Nanofluids in a Partially Heated Horizontal Circular Tube

Enhancement of cooling performance of heat transfer fluids can contribute to downsizing of thermal systems. Analysis of thermal behavior of four cooling water based nanofluids (CuO, Al2O3, ZnO and SiO2) in a circular duct is carried. Modeling of heat transfer and fluid flow is based on 3D non-linear differential elliptical equations and finite volume method approach. The Brownian motion is considered in modeling of the nanofluid behavior. A code is developed based on SIMPLER and TDMA algorithms. Hydrodynamic and thermal fields are examined for nanoparticles volume fractions range 0% ≤ Φ ≤ 4% and spherical nanoparticles mean diameter in the range 27 nm ≤ dnp ≤ 78 nm. Results show that the local and circumferentially average Nusselt number increases with increasing the nanoparticles volume fraction and decreases with the nanoparticles size. The maximum local Nu is observed at the bottom of the duct. SiO2–water nanofluid shows the best thermal performance as well as the strongest secondary flow. Increasing the nanoparticles volume fraction increases the secondary flow strength. Using 4 vol.% nanoparticles of 27 nm mean diameter improves Nu by 12%, 7%, 5%, and 3.7% for SiO2, Al2O3, ZnO, CuO, respectively, when compared to the cooling performance of water alone.

OPTIMIZATION AND GREEN SYNTHESIS OF SILVER AND GOLD NANO-PARTICLES DERIVED FROM COLOCASIA ESCULENTA ROOT EXTRACT AND THEIR POTENTIAL PHARMACOLOGICAL APPLICATIONS

The broad array of potential applications of silver and gold nano-particles in diverse fields is well-known. The utilization of lethal reagents is included in the contemporary procedures of synthesizing nanoparticles. In present times, there is necessity to augment novel mechanisms that lead to the synthesis of gold and silver nano-particles with the help of environmentally safe reagents. The reliable green synthesis of silver and gold nano-particles with the help of Colocasia esculenta root extract popularly called as Arvi, has been investigated here. The experimental procedure employed here to scrutinize and observe the synthesis of silver and gold nano-particles based on quantity is UV-Vis absorption spectroscopy. Surface Plasmon Resonance (SPR) was exhibited by UV/Vis spectrum for silver and gold nano-particles at 420 and 540 nanometers, respectively. The mean diameter of gold and silver nanoparticles synthesized in the solution was found to be 85 nm and 105 nm, respectively. The particles that were synthesized had a spherical shape.

Copper Oxide Nanoparticles over Hierarchical Silica Monoliths for Continuous-Flow Selective Alcoholysis of Styrene Oxide

A simple and reproducible approach for the synthesis of Cu-based heterogeneous catalysts, named flow chemisorption hydrolysis (flow-CH), is reported. The approach, derived from the CH method, allows size-controlled CuO nanoparticles (mean diameter 2.9 nm) to be obtained, that are highly and homogeneously dispersed into hierarchically meso-/macroporous silica monoliths. The Cu-based monolithic catalysts (CuO@SiO2-MN, 8.4 wt.% Cu) were studied in the styrene oxide ring opening reaction at 60 °C in the presence of isopropanol, under continuous flow-through conditions. A remarkable activity with a steady-state conversion of 97% for 13 h and 100% selectivity towards the corresponding β-alkoxyalcohol was observed. The performances of CuO@SiO2-MN were higher than those obtained in batch conditions with the previously reported CuO/SiO2 catalysts and with the ground CuO@SiO2-MN monolith in terms of productivity and selectivity. Moreover, a negligible Cu leaching (<0.6 wt.%) in reaction medium was observed. After 13 h CuO@SiO2-MN catalysts could be regenerated by a mild calcination (220 °C) permitting reuse.

Synthesis and Characterization of Ligand-Stabilized Silver Nanoparticles and Comparative Antibacterial Activity against E. coli.

Silver is a well-established antimicrobial agent. Conjugation of organic ligands with silver nanoparticles has been shown to create antimicrobial nanoparticles with improved pharmacodynamic properties and reduced toxicity. Twelve novel organic ligand functionalized silver nanoparticles (AgNPs) were prepared via a light-controlled reaction with derivatives of benzothiazole, benzoxazine, quinazolinone, 2-butyne-1,4-diol, 3-butyne-1-ol, and heptane-1,7-dioic. UV-vis, Fourier-transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray (EDAX) analysis were used to confirm the successful formation of ligand-functionalized nanoparticles. Dynamic light scattering (DLS) revealed mean nanoparticle diameters between 25 and 278 nm. Spherical and nanotube-like morphologies were observed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Seven of the twelve nanoparticles exhibited strong antimicrobial activity and five of the twelve demonstrated significant antibacterial capabilities against E. coli in a zone-of-inhibition assay. The synthesis of functionalized silver nanoparticles such as the twelve presented is critical for the further development of silver-nanoconjugated antibacterial agents.

Accurate nanoparticle size determination using electrical mobility measurements in the step and scan modes

A critical and extensive comparison was made between differential mobility analysis (DMA) measurements of the mean diameter of monodisperse gold nanoparticles (AuNPs), based on step-voltage mode and the more commonly used scan-voltage mode (commercially known as scanning mobility particle sizer, SMPS). Under specific conditions including a long scan time, the difference between mean diameters measured by the two modes of operation was less than the expanded combined uncertainty (95% confidence interval) for the step-voltage mode. In addition, a comparison was made between two different calibration methods for DMA: the use of a certified nanoparticle size standard (artifact) versus a direct measurement of the sheath flow rate. Important variables and limitations for accurate measurements by the scan-voltage method were identified and evaluated. The mean size shifts to smaller electrical mobility diameters as the scan time is reduced and the scan mode is unable to measure sufficient points across the peak of very narrow size distributions, leading to systematic errors. The use of a calibration particle corrects for the flow and DMA column geometric effects and was found to minimize the effect of a reduced scan time. A methodology is presented for the use of these AuNPs and other monodisperse calibration particles for accurately calibrating SMPS instruments for the measurement of the electrical mobility diameter distribution.Copyright © 2022 American Association for Aerosol Research

Bevacizumab encapsulation into PLGA nanoparticles functionalized with immunouteroglobin-1 as an innovative delivery system for atherosclerosis

Atherosclerosis represents one of the main causes of death in the Western world. It is a multifactorial pathology characterized by lesions that reduce the lumen of the vessels causing serious clinical events. The extra-domain B of fibronectin is overexpressed during angiogenesis and in tissues undergoing growth and extensive remodeling, i.e., atherosclerotic plaque. Bevacizumab is a recombinant humanized monoclonal antibody that can play a central role against angiogenesis reducing the risk associated with this process in atherosclerosis. In this work, an innovative nanosystem for the targeted delivery of bevacizumab to the atherosclerotic lesion is proposed.A production protocol for poly(lactic-co-glycolic acid)-polyethylene glycol nanoparticles loaded with bevacizumab and functionalized with immunouteroglobin-1 was designed. Once functionalized nanoparticles with immunouteroglobin-1 were produced, they were characterized in terms of morphology, mean diameter, ζ-potential, association and conjugation efficiencies, bevacizumab release profile, both in phosphate buffered saline and in serum, bevacizumab stability after release, cytocompatibility, and hemocompatibility. Nanoparticle mean diameter was in the range of 217–265 nm, their surface charge was between −22 and −8 mV, and the association and conjugation efficiencies of about 76 and 59 %, respectively. Fourier transform infrared spectroscopy analysis confirmed the functionalization of their surface with immunouteroglobin-1. In vitro assays showed that the studied nanoparticles were cytocompatible, once in contact with human endothelial and murine macrophage cell lines up to 72 h, and hemocompatible, once in contact with red blood cells, at different concentrations of encapsulated bevacizumab (0.1, 1, 10, and 100 μg/mL).

The Effect of Nano-ZrO2 Dispersed Phase into Cobalt Plating Electrolyte on Layer Thickness and Current Efficiency

The aim of this work is to obtain nanocomposite layers having a cobalt matrix with zirconium oxide nanoparticles (mean diameter 30 nm) through the electrodeposition process. The plating electrolyte suspension is prepared by adding ZrO2 nanoparticles in a sulfate-chloride cobalt electrolyte at a concentration of 0 and 10 g·L−1. The electrodeposition is performed at room temperature, using three current densities of 23, 48 and 72 mA·cm−2 and three deposition times of 30, 60 and 90 min. The influence of current density, time and nanoparticles concentrations on the characteristics of the obtained nanostructured layers are also discussed. ZrO2 ceramic nanoparticles as a dispersed phase in the cobalt deposition electrolyte modify the mechanism of its electro-crystallization, so they participate in this process by increasing the rate of cobalt deposition, confirmed by the thickness of the nanocomposite layers obtained. The paper presents some of the comparative results obtained regarding the thickness of the layers, the current efficiency and the inclusion of the nanoparticles into nanocomposite layers depending on the current density and time of the electrodeposition process. The analysis of Co/nano-ZrO2 nanocomposite layers with the help of optical light microscopy and electronic microscopy in cross-section highlights the good degree of adhesion of the layers to the metallic substrate made of 304L stainless steel. The results of the study show that as the current density and time increase, the thickness of the composite layers increases. The efficiency of the process is improved compared to the electrodeposition of pure cobalt layers. The degree of inclusion of ZrO2 nanoparticles increases with time and decreases with increasing of imposed current density on the electrodeposition process. The distribution of the dispersed phase in the cobalt metallic matrix is uniform. The layers obtained in this study can be applied in aircraft technology, in the automotive industry, as well as in biomedical applications in order to improve the properties and to increase the corrosion or tribocorrosion resistance in a specific environment.

Sterically Stabilized Diblock Copolymer Nanoparticles Enable Convenient Preparation of Suspension Concentrates Comprising Various Agrochemical Actives.

It is well known that sterically stabilized diblock copolymer nanoparticles can be readily prepared using polymerization-induced self-assembly. Recently, we reported that such nanoparticles can be employed as a dispersant to prepare micron-sized particles of a widely used fungicide (azoxystrobin) via ball milling. In the present study, we examine the effect of varying the nature of the steric stabilizer block, the mean nanoparticle diameter, and the glass transition temperature (Tg) of the core-forming block on the particle size and colloidal stability of such azoxystrobin microparticles. In addition, the effect of crosslinking the nanoparticle cores is also investigated. Laser diffraction studies indicated the formation of azoxystrobin microparticles of approximately 2 μm diameter after milling for between 15 and 30 min at 6000 rpm. Diblock copolymer nanoparticles comprising a non-ionic steric stabilizer, rather than a cationic or anionic steric stabilizer, were determined to be more effective dispersants. Furthermore, nanoparticles of up to 51 nm diameter enabled efficient milling and ensured overall suspension concentrate stability. Moreover, crosslinking the nanoparticle cores and adjusting the Tg of the core-forming block had little effect on the milling of azoxystrobin. Finally, we show that this versatile approach is also applicable to five other organic crystalline agrochemicals, namely pinoxaden, cyproconazole, difenoconazole, isopyrazam and tebuconazole. TEM studies confirmed the adsorption of sterically stabilized nanoparticles at the surface of such agrochemical microparticles. The nanoparticles are characterized using TEM, DLS, aqueous electrophoresis and 1H NMR spectroscopy, while the final aqueous’ suspension concentrates comprising microparticles of the above six agrochemical actives are characterized using optical microscopy, laser diffraction and electron microscopy.

Smart Lipid-Polysaccharide Nanoparticles for Targeted Delivery of Doxorubicin to Breast Cancer Cells.

In this study, actively-targeted (CD44-receptors) and dual stimuli (pH/redox)-responsive lipid–polymer nanoparticles were proposed as a delivery vehicle of doxorubicin hydrochloride in triple negative breast cancer cell lines. A phosphatidylcholine lipid film was hydrated with a solution of oxidized hyaluronic acid and doxorubicin, chosen as model drug, followed by a crosslinking reaction with cystamine hydrochloride. The obtained spherical nanoparticles (mean diameter of 30 nm) were found to be efficiently internalized in cancer cells by a receptor-mediated endocytosis process, and to modulate the drug release depending on the pH and redox potential of the surrounding medium. In vitro cytotoxicity assays demonstrated the safety and efficacy of the nanoparticles in enhancing the cytotoxic effect of the free anticancer drug, with the IC50 values being reduced by two and three times in MDA-MB-468 and MDA-MB-231, respectively. The combination of self-assembled phospholipid molecules with a polysaccharide counterpart acting as receptor ligand, and stimuli-responsive chemical moieties, was carried out on smart multifunctional nanoparticles able to actively target breast cancer cells and improve the in vitro anticancer activity of doxorubicin.

Effect of liquid medium and laser processing parameters on the fabrication of carbon nanoparticles via pulsed laser ablation in liquid towards paper electronics

Paper-based electronics with carbon nanomaterials incorporated have several advantages including recyclability, biodegradability, non-toxicity, low cost and ease of fabrication and disposal. Herein, carbon nanoparticles (CNPs) were fabricated by Pulsed Laser Ablation in Liquid (PLAL) using three different liquid mediums, i.e. deionised (DI) water, ethanol and a magnesium-based solution. The as-fabricated nanocolloids were used as conductive inks and deposited on paper substrates. The resulting nanoparticle (NP) coatings were subjected to electrical resistivity tests via 4-point probe. Ultraviolet–Visible spectroscopy (UV–Vis) studies were conducted to determine the presence of nanomaterials. All nanocolloids produced within DI water had three distinct UV–Vis absorbance peaks at 200, 216 and 225 nm while nanocolloids produced in ethanol exhibited more peaks and significantly higher absorbance values in the range from 210 nm to 300 nm. Dynamic Light Scattering and field emission scanning electron microscopy (FESEM) were used to analyse samples for particle size and morphology respectively. The liquid medium in which PLAL was conducted was found to significantly affect the NP mean size, conductivity and surface chemistry of the resulting NPs. DI water produced smaller nanoparticles (NPs) (10–82 nm) than ethanol (60–143 nm) and magnesium-based solution (263–1389 nm) within the process parameters studied herein. The laser scan speed and fluence have a combined effect on the NP mean diameter. The surface chemistry of the NPs produced in the magnesium-based solution was analysed via X-ray photoelectron spectroscopy and it was found that the Mg, Li and Si atoms are adsorbed by the carbon NPs leading to higher conductivity of the coated paper substrates.

Magnesium Nanoparticle Synthesis from Powders via Pulsed Laser Ablation in Liquid for Nanocolloid Production

Magnesium nanoparticles of various mean diameters (53–239 nm) were synthesised in this study via pulsed laser ablation in liquid (PLAL) from millimetre sized magnesium powders within isopropyl alcohol. It was observed via a 3 × 3 full factorial design of experiments that the processing parameters can control the nanoparticle distribution to produce three size-distribution types (bimodal, skewed and normal). Ablation times of 2, 5, and 25 min where investigated. An ablation time of 2 min produced a bimodal distribution with the other types seen at higher periods of processing. Mg nanoparticle Ultraviolet–Visible spectroscopy (UV–Vis) absorbance at 204 nm increased linearly with increasing ablation time, indicating an increase in nanoparticle count. The colloidal density (mg/mL) generally increased with increasing nanoparticle mean diameter as noted via increasing UV–Vis absorbance. High laser scan speeds (within the studied range of 3000–3500 mm/s) tend to increase the nanoparticle count/yield. For the first time, the effect of scan speed on colloidal density, UV–Vis absorbance and nanoparticle diameter from metallic powder ablation was investigated and is reported herein. The nanoparticles formed dendritic structures after being drop cast on aluminium foil as observed via field emission scanning electron microscope analysis. Dynamic light scattering was used to measure the size of the nanoparticles. Magnesium nanoparticle inks show promise for use in the fabrication conductive tracks or thermal insulation in electronics.

Biotin-functionalized silica nanoparticles loaded with Erythrosine B asselective photodynamic treatment for Glioblastoma Multiforme

In this contribution, we report the development of a biotin-functionalized silica nanoparticle loaded with Erythrosine B (ERY) to act as a selective cancer nanoplatform via Photodynamic Therapy. Amino silica nanoparticles were synthesized by the co-condensation method and further functionalized via amide linkage with biotin. The silica nanoparticles (mean diameter ∼120 nm) were loaded with ERY yieldings of 34.9 mg g−1 and 16.7 mg g−1, respectively, for the non-biotinylated (ERY/SiNP) and biotinylated (ERY/SiNP-B). The adsorption followed two consecutive first-order reactions, and the isotherms fitted to the Langmuir (SiNP) and Freundlich (SiNP-B) models. The ERY is strongly attached to the silica nanoparticle, which prevents their premature leakage to the biological fluids. The well-established effect of the uric acid as a singlet oxygen scavenger was used to show the 1O2 formation by the nanoplatforms. Trypan blue and MTT cytotoxic assays have shown that ERY/SiNP and ERY/SiNP-B samples are potential systems for PDT applications against Gliobastoma Multiforme (GBM) cancer cells vanishing around 50 % of T98G cells.

High-Yield Growth and Tunable Morphology of Bi2Se3 Nanoribbons Synthesized on Thermally Dewetted Au.

The yield and morphology (length, width, thickness) of stoichiometric Bi2Se3 nanoribbons grown by physical vapor deposition is studied as a function of the diameters and areal number density of the Au catalyst nanoparticles of mean diameters 8–150 nm formed by dewetting Au layers of thicknesses 1.5–16 nm. The highest yield of the Bi2Se3 nanoribbons is reached when synthesized on dewetted 3 nm thick Au layer (mean diameter of Au nanoparticles ~10 nm) and exceeds the nanoribbon yield obtained in catalyst-free synthesis by almost 50 times. The mean lengths and thicknesses of the Bi2Se3 nanoribbons are directly proportional to the mean diameters of Au catalyst nanoparticles. In contrast, the mean widths of the Bi2Se3 nanoribbons do not show a direct correlation with the Au nanoparticle size as they depend on the contribution ratio of two main growth mechanisms—catalyst-free and vapor–liquid–solid deposition. The Bi2Se3 nanoribbon growth mechanisms in relation to the Au catalyst nanoparticle size and areal number density are discussed. Determined charge transport characteristics confirm the high quality of the synthesized Bi2Se3 nanoribbons, which, together with the high yield and tunable morphology, makes these suitable for application in a variety of nanoscale devices.

Clustering of Diamond Nanoparticles, Fluorination and Efficiency of Slow Neutron Reflectors.

Neutrons can be an instrument or an object in many fields of research. Major efforts all over the world are devoted to improving the intensity of neutron sources and the efficiency of neutron delivery for experimental installations. In this context, neutron reflectors play a key role because they allow significant improvement of both economy and efficiency. For slow neutrons, Detonation NanoDiamond (DND) powders provide exceptionally good reflecting performance due to the combination of enhanced coherent scattering and low neutron absorption. The enhancement is at maximum when the nanoparticle diameter is close to the neutron wavelength. Therefore, the mean nanoparticle diameter and the diameter distribution are important. In addition, DNDs show clustering, which increases their effective diameters. Here, we report on how breaking agglomerates affects clustering of DNDs and the overall reflector performance. We characterize DNDs using small-angle neutron scattering, X-ray diffraction, scanning and transmission electron microscopy, neutron activation analysis, dynamical light scattering, infra-red light spectroscopy, and others. Based on the results of these tests, we discuss the calculated size distribution of DNDs, the absolute cross-section of neutron scattering, the neutron albedo, and the neutron intensity gain for neutron traps with DND walls.

Structure, assembly and application of novel peanut oil body protein extracts nanoparticles

Oil bodies (OBs), which are found mainly in the seeds or nuts of oleaginous plants, are spherical droplets with a triacylglycerol core covered by phospholipid-protein layer. Oil body protein extracts (OBPEs), mainly oleosins, contribute to the unique physicochemical stability of OBs. The application of OBPEs in aqueous environment has been greatly limited by their highly hydrophobic structures. In this study, OBPEs were successfully extracted from peanut seeds and their profiles were characterized by LC-MS/MS. OBPEs nanoparticles were successfully assembled in aqueous environment for the first time using the antisolvent precipitation method. The mean diameter of OBPEs nanoparticles was 215.6 ± 1.8 nm with a polydispersity index of 0.238 ± 0.005. The morphology of these colloidal particles was found to be roughly spherical shape as confirmed by transmission electron microscopy (TEM). Oil-in-water (O/W) Pickering emulsions with good stability against coalescence could be formed at protein concentration as low as 0.1 mg/mL. Cryo-scanning electron microscopy (cryo-SEM) confirmed that spherical nanoparticles were packed at the oil–water interface. This research will greatly expand the applications of OBPEs in structuring the interfaces and developing novel formulations in the food and pharmaceutical fields.

Silibinin-Albumin Nanoparticles: Characterization and Biological Evaluation Against Oxidative Stress-Stimulated Neurotoxicity Associated with Alzheimer's Disease.

Alzheimer's disease (AD) is strongly associated with oxidative stress which can damage neural cells. Silibinin has shown potential antioxidative effects. However, due to its low solubility in water, silibinin provides low biological activity and bioavailability. Therefore, to increase its pharmacological effects, silibilin was encapsulated into human serum albumin (HSA) nanoparticles and well-characterized by DLS and TEM techniques. The antioxidant activity of silibinin-HSA nanoparticles was evaluated on LPS-induced oxidative stress in neuron-like cells (SH-SY5Y) through MTT, antioxidant activity and apoptotic assay. It was shown that the mean diameter of HSA and silibinin-HSA nanoparticles were 88 and 105 nm, respectively with a drug loading of 24.08%, drug encapsulation rate of 94.72%, and the yield of silibinin-HSA nanoparticles of around 83.41% and the HSA nano-formulation released silibinin for 15 h. The results displayed that cell viability was reduced by LPS (10 μg/mL), who's also determined to stimulate oxidative stress and apoptosis. However, co-incubation of cells with silibinin (50 μg/mL) or silibinin-HSA nanoparticles led to the recovery of cell viability, activation of SOD and CAT, increase of GSH content, and reduction of ROS level, Caspase-3 activity and fragmentation of DNA. It was also indicated that the neuroprotective and antioxidant activities of silibinin-HAS nanoparticles was greater than free silibinin, indicating that using albumin can be a potential formulation approach for improving the antioxidant efficacy of silibinin.

Contactless magnetic nanoparticle detection platform based on non-linear GMI effect

A detection platform based on non-linear Giant Magnetoimpedance Effect was analyzed for the design of a contactless and low-cost detector of magnetic nanoparticles. The sensor consists of two soft magnetic amorphous wires (Co66Fe2Si13B15Cr4, 1.5 cm in length) placed in parallel and connected electrically in series. Initially, a simple voltage divider was employed to characterize the variations of the first, V1fand second harmonic, V2f, voltages. Their response was analyzed under the effect of the remnant magnetic field generated by different amounts of Fe3O4 nanoparticles (mean diameter 140 nm) as a function of an external magnetic field, H. Due to the larger relative variations showed by V2f, the second harmonic was chosen for the final prototype development. An electronic interface was designed for both current excitation and V2f detection. The designed detection platform, characterized by high detection sensitivity, low-cost, portable, and reusable features, can be employed to efficiently detect magnetic nanoparticles.

Specific heat capacity of molten salt-based nanofluids in solar thermal applications: A paradigm of two modern ensemble machine learning methods

The quantitative determination of specific heat capacity (SHC) of molten (nitrate) salt-based nanofluids helps to control the start-up heat and prevent overheating when deployed as a working heat transfer fluid in a wide range of solar thermal applications. Thus, accurate measurement of the SHC and capturing the melting point is of paramount importance in the molten salt-based nanofluids’ characterization analyses applied in solar collectors. In this research, two modern ensemble machine learning models, Extra Tree Regression (ETR) and AdaBoost Regression (ABR), were developed based on 2,384 datasets, including solid mass fraction (w), temperature (T), SHC of base fluid (CPBase), mean diameter (Dp), and density (ρp) of nanoparticle as all independent input variables and the SHC of molten salt-based nanofluids (CPMS-nf) as the target. Herein, the stepwise forward method and mutual information were addressed to determine the best input combination and sensitivity analysis. The provided models were validated using Random Forest (RF) and Boosted Regression Tree (BRT) as two powerful other ensemble models. The results demonstrated that ETR model in terms of (R = 0.9964, RMSE = 0.1566, and U95%=3.6062) outperformed the ABR (R = 0.9949, RMSE = 0.1855, and U95%=3.6009), RF (R = 0.9922, RMSE = 0.2326, and U95%=3.5904), and BRT (R = 0.9907, RMSE = 0.2508, and U95%=3.5857). The SHC of molten salt base fluid was identified as the most significant factor in estimating the SHC of molten salt-based nanofluids.

Feasibility, processing properties and thermal behavior of Ni nanopastes produced by ultrasound-enhanced dispersing

Nickel nanoparticles are materials that can be used for a novel type of joining, so called nanojoining, as an alternative to conventional brazing. The physical characteristics of these nano-sized particles lead to a lower melting temperature compared to nickel bulk material and even lower than typical brazes, without the need for melting point depressants. Such elements like boron or silicon cause issues due to formation of brittle intermetallic phases. In order to be able to use Ni nanoparticles in practical applications, they have to be in forms such as suspensions, e.g pastes. In the present work, therefore, a series of Ni nanopastes is prepared and investigated with emphasis on the solvent systems. These suspensions consist of Ni nanoparticles (mean diameter 20 / 90 / 180 / 300 nm) and organic compounds. The examinations show the feasibility of producing such nanopastes using ultrasound-enhanced dispersing, as well as margins for adjusting their processing properties. In addition, first results of the thermal behavior of the Ni nanopastes, measured by simultaneous DSC/TG, are shown.