Oxide Particle Size Research Articles

Lanthanoid Sesquioxide Ultrafine Nanoparticles on Graphene via General Approach of Ultrafast Redox Reaction and Their Performance as Anodes in Lithium-Ion Batteries.

Herein, we propose a general route of obtaining reduced graphene oxide and metal oxide nanocomposite, demonstrated by cerium, dysprosium, and neodymium sesquioxides, via ultrafast redox reaction (URR). This method utilizes a very fast heating of graphene oxide and a metal salt without any chemical solvents or special reactors. Off the scene tests showed that different ratios of graphene oxide to metal salt change the metal oxide particle size. Morphological, structural, physicochemical, and electrochemical properties were investigated. It was proved via X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) data that it was also possible to oxidize dysprosium acetate and neodymium nitrate at 300 °C, which normally would require much higher temperatures. As-obtained nanocomposites were tested as anodes in Li-ion batteries, but their applications should be further expanded to different fields. As Li-ion anodes, they delivered capacity as high as 1173 mAh/g at 0.05 A/g. Interestingly, ex situ measurements of the anode material showed that upon charging ceria is activated to form multiwalled carbon nanotubes. In this respect, we believe that the URR route is an ultrafast method (lasts in an eyeblink emitting colorful sparkles and smoke) to design graphene/metal oxide nanocomposites with tuned nanoparticle size at lower temperatures and without solvents which represents a facile and environmentally friendly approach for various applications.

Effects of exopolysaccharides from Rhizobium tropici on transformation and aggregate sizes of iron oxides

Iron oxide transformations in soil significantly impact nutrient availability and plant health. This study investigated the interaction between exopolysaccharides (EPS), produced by Rhizobium tropici, and iron oxide (Fe3O4), focusing on their impact on the transformation, particle size, and zeta potential of iron oxides. The characterization of the EPS-iron oxide composites was carried out using X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM)/Energy Dispersive X-ray Analysis (EDX). The EPS adsorption kinetics revealed chemisorption and diffusion as controlling processes for EPS adsorption on Fe3O4, while isotherm data with releasing proton indicated possible ion exchange and heterogeneous layered adsorption. Desorption studies suggested the high stability of EPS-iron complexes. Notably, EPS significantly increased the aggregate size of EPS-iron complexes at low EPS/iron oxide molar ratios but shrank the aggregate size at higher ratios (> EPS/iron oxide 2 × 10−4). Additionally, EPS complexation resulted in a shift in the zeta potential towards more negative surface functionality. Functional groups within EPS, specifically –COOH, –OH and –NH played a crucial role in the interaction of EPS with iron oxides. The study concluded that EPS coating prevented the transformation of Fe3O4 into other iron oxide forms like β-FeOOH, α-Fe2O3, and γ-Fe2O3, elucidating the significant role of EPS in soil mineral processes.

Effect of tin oxide particle size on epoxy resin to form new composites against gamma radiation

The aim of the present study is to assess the shielding performance of a novel lead-free epoxide material against ionizing radiation. The effect of variation in particle size and concentration of tin oxide (SnO), which was added to epoxy resin polymer (ER), on its radiation shielding properties has been investigated in this research. Ten samples of ER samples incorporated with different concentrations (0%,20%,40%,60%) of SnO microparticles, nanoparticles, and both sizes combined were prepared and assessed. The linear attenuation coefficients (LAC) were measured experimentally through the collimated gamma-ray beam at 0.0595 MeV, 0.6617 MeV, 1.1730 MeV, and 1.330 MeV emitted from Am-241, Cs-137 and Co-60, respectively (to cover all energy range of gamma rays) for all samples with various concentrations and particle sizes of SnO. The other radiological shielding parameters such as half value layer (HVL), tenth value layer (TVL), and radiation protection efficiency (RPE) were estimated and compared for all different samples. The results prove that the increasing of the concentration and reducing the particle size of SnO leads to the enhancement of the radiation protection properties of the ER polymer. Moreover, it was observed that the incorporation of SnO micro- and nanoparticles together improves the radiation shielding properties of ER samples. Conclusively, the reinforcing of ER polymer material matrix by micro/nanoparticles of SnO as composite with enhanced radiation shielding specifications was highlighted.

Exploration of the reactivities of homemade binary pyrotechnics

Understanding the properties of explosives is the basis for investigating and analyzing explosion cases. To date, due to the strict legal control of standard explosives and initiators, homemade pyrotechnics composed of oxidizers and fuels have become popular explosive sources of improvised explosive devices (IEDs) threatening greatly social stability and personal safety. The reactivity of pyrotechnics strongly depends on their intrinsic characteristics and operating conditions, which determine the efficiencies of heat and mass transfer between the reaction zone and the unreacted zone. Herein, the tests of thermodynamics, pressurization characteristics, and combustion propagation behaviors are conducted to explore the effects of oxidizer species, particle size, and loading density on the reactivity of homemade binary aluminum-based pyrotechnics. The results show that the pyrotechnics with potassium chlorate (KClO3) have the strongest reactivity with the highest pressurization rate (dp/dt) and the shortest combustion duration. Compared with their counterparts based on aluminum microparticles(mAl), pyrotechnics consisting of Al nanoparticles (nAl) possess superior reactivity as expected, which results from the relatively short heat and mass transfer distances. The nAl-based pyrotechnics have a low reaction exothermic peak temperature, great heat release, great aluminothermic reaction completeness, and high produced peak pressure with several orders of magnitude higher pressurization rate. Increasing the loading density of the pyrotechnics over a certain value can change the dominant mode of heat transfer from convective to conduction, sharply decreasing the pressurization characteristics and combustion front propagation velocities (vp). The results of theoretical calculations using the NASA-CEA codes show that loading density can alter the reaction process of the pyrotechnics, leading to a decrease in the predicted pressure per unit mass for Al/KNO3 or Al/AP, and an increase for Al/KClO3. For nAl/potassium nitrate (KNO3), the density is between 1.0 and 1.25 g cm−3, across which dp/dt decreases by one order of magnitude from 0.148 to 0.014 MPa ms−1. In addition, vp decreases by three orders of magnitude from 0.040 to 0.078 m s−1. Distinct pressurization behaviors of nAl/AP are observed at a density of 1.5 g cm−3, while the variation in nAl/KClO3 reactivity fluctuates. These results are beneficial for the damage assessment of scenes caused by an explosion and for inversely calculating charge parameters.

Effects of Zr addition on the microstructure and mechanical properties of Y-Zr-O complex oxide dispersion-strengthened Mo alloys

Y-Zr-O complex oxide dispersion-strengthened Mo alloys with different Zr contents (Mo-2Y2O3–0.6Zr, Mo-1Y2O3–0.6Zr, and Mo-1Y2O3–1.2Zr, wt%) were designed and fabricated by mechanical alloying and spark plasma sintering to investigate the effect of Zr addition on the microstructure and mechanical properties of this Mo alloy. The size and spatial distribution of oxide particles were characterized using Fresnel contrast mode in TEM, and mechanical properties were measured using small-scale three-point bending tests. Results show that Zr addition leads to the coarsening of oxide particles, especially intergranular particles. Based on Weibull theory, the strength ratio of Mo alloys in three-point bending and tensile tests is well fitted as 1.70. Furthermore, the Mo-2Y2O3–0.6Zr alloy exhibits an unprecedented tensile strength and fracture strain of 1059 MPa and 1.01 %, attributed to its ultrafine Mo grains (∼0.3 μm), semi-coherent intragranular oxide nanoprecipitates (∼18.09 nm), and intergranular oxide nanoprecipitates (∼67.11 nm). The theoretical calculation indicates that the strength is mainly affected by grain boundary strengthening and intragranular particle strengthening. The findings can provide a beneficial reference for the relationship between microstructure and mechanical properties of high-performance Mo alloy for nuclear energy applications.

INFLUENCE OF FILLER SIZE ON THE STRUCTURE AND PROPERTIES OF THE POLYMER MATRIX

Purpose. The aim of the study is to investigate the influence of aluminum oxide (Al2O3) particle size on the mechanical properties of a polymer composite with added chopped glass fiber, as well as to explore the interaction between aluminum oxide particles and chopped glass fiber. Research methods. Specimens were tested for tensile strength according to DSTU EN ISO 527-5:2018. Testing was conducted using an MTS Criterion Model 43 universal testing machine with a maximum load of 50 kN. Metallographic analysis was performed using a KEYENCE VHX microscope at magnifications of 50× and 500×. The microstructure of the polymer matrix was determined on unetched samples. Scanning electron microscopy was carried out using a JEOL JSM-5510LV microscope. Results. The influence of introducing different sizes of aluminum oxide fraction on the polymer matrix was studied. It was found that with an increase in the fraction size, the strength of the polymer composition decreases. Additionally, the interaction between chopped glass fiber and various fractions of aluminum oxide on the mechanical characteristics and morphology of the connection with the polymer composition was investigated. Scientific novelty. The interaction of chopped fiber with aluminum oxide fractions may affect the mechanical properties of the composite, such as strength, stiffness, and elasticity. Investigation of the morphology of the connection between chopped fiber and aluminum oxide fractions can help understand how they interact within the composite structure. This includes analyzing the adhesion between components, the structure of junctions, and possible defects that may arise during the manufacturing process. Studying this interaction opens up opportunities for the development of new composite materials with improved properties and diverse applications in industry, construction, aviation, automotive, and other fields. Practical value. The practical significance lies in refining manufacturing technologies and implementing new materials in industry. The ability to control the mechanical properties of composites by changing the size of aluminum oxide fractions can contribute to the creation of more efficient materials for the production of automobiles, aircraft, building constructions, and more. Additionally, understanding the interaction between chopped glass fiber and aluminum oxide fractions may open up new possibilities for developing composites with unique mechanical characteristics that meet the requirements of modern technologies and industrial production.

A Kinetic Model for Oxide–Carbonitride Inclusion Heterogeneous Nucleation and Precipitation during Superalloy Solidification

Complex oxide–carbonitrides (MgO-Ti(CN), Al2O3-Ti(CN), and MgO·Al2O3-Ti(CN)) are the most common non-metallic inclusions presented in cast and wrought superalloys. In this work, a coupled kinetics model was proposed to predict the complex oxide–carbonitride inclusion’s precipitation behavior during the solidification of superalloys. This model takes into account thermodynamics, micro-segregation, heterogeneous nucleation in the inter-dendritic liquid, and growth controlled by the diffusion of solute elements and kinetics of interfacial reaction. The results demonstrated that both the cooling rate and nitrogen content take significant effects on the final size of complex oxide–carbonitride inclusions, as the former controls the total growth time and the latter determines the initial precipitation temperature. In comparison, the particle size of primary oxides shows a negligible impact on the final size of complex inclusions. The practice of an industrial vacuum arc remelting confirmed that the inclusion size variation predicted by the present model is reasonably consistent with the experimental results.

Study on Cycle Performance and Rate Performance of Lithium Cobalt Oxide

Lithium cobalt oxide (LiCoO2 ) cathode material, with its high energy density and operating voltage, is currently a mainstream material for lithium-ion battery cathodes.   However,  the  crystal  structure  collapse  and  lattice  oxygen  evolution under high-voltage conditions lead to rapid capacity decay, severely limiting its practical applications.   This paper  analyzes the main factors affecting the cycle performance and rate performance of lithium cobalt oxide, considering the physic- ochemical properties of the particles, including elemental content and particle size, and provides a mathematical model linking these properties to electrochemical per- formance.  The study offers insights for the practical production of high-voltage lithium cobalt oxide materials. At the beginning, we embarked on investigating the correlation between the physicochemical attributes (encompassing elemental composition and particle size) of lithium cobalt oxide and its cycle performance. An Ordinary Least Squares (OLS) linear regression model was formulated, yielding a robust fit with an R-Squared value of 0.94. This model was subsequently optimized through the application of an XGBoost algorithm, achieving an R-Squared value nearing unity, signifying a remarkable enhancement in model accuracy. Visual analysis of the results pinpointed the primary determinants of cycle performance, arranged in descending order of significance: 'Cycle Index,' Mg content, particle size distribution (D10), Zn, and Al. Then, our attention shifted to examining the link between the aforementioned physicochemical characteristics and the rate performance of lithium cobalt oxide. The Jarque-Bera and Shapiro-Wilk tests confirmed the normality of the data, fulfilling the prerequisites for hypothesis testing. An OLS linear regression model was developed, demonstrating a strong goodness-of-fit with an R-Squared value exceeding 0.8. This model was further honed with an XGBoost model, which achieved an R-Squared score approaching 1, indicating a substantial refinement in model precision. The visualization of model outcomes illuminated the key factors influencing rate performance, ranked in descending order of importance: particle size distribution (D50), Al, Mn, Zn, Mg, Ni, and Fe. Lastly, we devised an optimal strategy that encompasses the incorporation of strategic doping elements, the utilization of high-temperature sol-gel methods to bolster cycle performance, and coating modifications aimed at enhancing rate performance. This holistic approach fosters the structural stability of lithium cobalt oxide crystals, fortifying their high-potential cycle capabilities, and concurrently elevating their rate performance.

Influence of pegylated graphene oxide nanoparticles on the respiratory burst and phagocytic activity of human neutrophils

Scientific and technological progress contributes to the discovery and production of innovative materials. The emergence of graphene is a clear example of this. Graphene is considered a promising material for use in nanobiomedicine and nanobiotechnology. It is therefore important to understand how it affects human immune cells. In a study, the effects of 5 and 25 μg/mL graphene oxide nanoparticles with lateral sizes of 100-200 nm and 1-5 μm, modified with linear and branched polyethylene glycol, on human neutrophils were investigated. The formation of reactive oxygen species was evaluated with a lucigenin as a chemiluminescence activator.Inaddition, we investigated theeffect of a 60-minute incubation of neutrophils with pegylated graphene oxide nanoparticles on the viability of these cells by staining with trypan blue and a 30-minute incubation on the uptake of fluorescein isocyanate-labelled E. coli. The percentage of neutrophils which engulfed E. coli and the uptake index were determined. Samples without added nanoparticles served as controls.A decrease in lucigenin-enhanced chemiluminescence of neutrophils was observed under the influence of two types of graphene oxide nanoparticles: 1-5 μm in size coated with linear polyethylene glycol, and 100-200 nm in size coated with branched polyethylene glycol, at a concentration of 25 μg/mL in the zymosan-stimulated version of the assay. No dependence of the effect on the particle size and the type of polyethylene glycol was observed. The indicators for spontaneous chemiluminescence of neutrophils did not change with the addition of PEGylated graphene oxide nanoparticles.A thirty-minute incubation of human neutrophils at 37 °C with PEGylated graphene oxide nanoparticles with lateral dimensions of 100-200 nm and 1-5 μm had no effect on the viability of these cells and on the percentage of neutrophils that engulfed E. coli. However, 1-5 μm graphene oxide modified with linear polyethylene glycol at a concentration of 25 μg/mL increased the amount of E. coli engulfed by neutrophils per cell.Thus, in the absence of cytotoxicity, PEGylated graphene oxide particles have multidirectional immunomodulatory effects on neutrophils. In this case, their concentration is decisive and not the size of the graphene oxide particles and the type of polyethylene glycol.

Creep behavior of a novel ODS ferrite steel reinforced with ultra-fine Y2(Zr0.6, Ti0.4)2O7 particles

Oxide dispersion strengthened (ODS) ferrite steel is a competitive candidate structural material for the Generation IV fission reactors. In this work, a novel ODS ferrite steel reinforced with ultra-fine Y2(Zr0.6, Ti0.4)2O7 particles was prepared by powder metallurgy method, which exhibit superior mechanical properties at elevated temperatures. Creep tests of the ODS ferrite steel at 800 °C was conducted to reveal its high-temperature creep failure mechanism. This ODS steel has an average grain size of 1.31 μm, and the mean size and number density of the ultra-fine oxide particles are 5.48 nm and 4.85 × 1023 m−3, respectively. When the applied creep stress is 100 MPa, the creep rupture time of the ODS steel is 2448.5 h, and the minimum creep rate is only 1.05 × 10−7 s−1. Under the similar creep stress at 800 °C, the creep rate of this ODS steel is at least one order of magnitude lower than that of other typical ODS steels reported in the literatures, showing excellent creep properties. By fitting the data of minimum creep rate, applied stress and effective stress normalized by shear modulus, the creep threshold stress of the ODS steel was determined as 56.2 MPa, and the true stress exponent was calculated as 4.5 ± 1.0, which indicates that the creep mechanism is dominated by dislocation. Orowan bypass mechanism and dislocation climb over the particle mechanism play a major role in this dislocation mediated creep behavior. Due to the strong hindering effect of dislocation motion caused by the ultra-fine and dispersed Y2(Zr0.6, Ti0.4)2O7 particles, the novel ODS ferrite steel thereby achieved excellent creep properties.

Effect of Bi2O3 Particle Size on the Radiation-Shielding Performance of Free-Lead Epoxide Materials against Ionizing Radiation.

In this work, we studied the effect of bismuth oxide particle size and its attenuation capacity as a filler additive in epoxy resins. Six samples were prepared according to the amount of microparticles and nanoparticles in the sample and were coded as ERB-1, ERB-2, ERB-3, ERB-4, ERB-5, and ERB-6. One of the composite epoxies contained Bi2O3 microparticles at a 50:50 ratio (ERB-6) and was chosen as the control composite, and the number of microparticles (MPs) was gradually decreased and replaced by nanoparticles (NPs) to produce epoxy-containing Bi2O3 nanoparticles at a 50:50 ratio (ERB-1). The morphological and thermal characteristics of the studied composites were tested. The attenuation capability of the prepared composites, which is determined by the Bi2O3 particle size, was determined experimentally using a semiconductor detector, an HPGe-detector, and three different gamma-ray point sources (Am-241, Co-60, and Cs-137). The linear attenuation coefficient (LAC) of ERB-3, which contained 30% nanoparticles and 20% microparticles, had the highest value compared to the other composites at all the energies discussed, while the ERB-6 composite had the lowest value at all energies. The radiation-shielding efficiency (RSE) of the prepared samples was determined at all discussed energies; at 662 keV, the radiation-shielding efficiency values were 15.97%, 13.94%, and 12.55% for ERB-3, ERB-1, and ERB-6, respectively. The statistics also proved that the attenuation capacities of the samples containing a combination of nanoparticles and microparticles were much superior to those of the samples containing only microparticles or nanoparticles. A ranking of the samples based on their attenuation capacity is as follows: ERB-3 > ERB-4 > ERB-2 > ERB-1 > ERB-5 > ERB-6.

Enhancing electrochemical capacity and interfacial stability of lithium-ion batteries through side reaction modulation with ultrathin carbon nanotube film and optimized lithium cobalt oxide particle size

Enhancing electrochemical capacity and interfacial stability of lithium-ion batteries through side reaction modulation with ultrathin carbon nanotube film and optimized lithium cobalt oxide particle size

Effect of pressure, Mg content and AP size on the microscale flame structure of Mg-based propellant

The Mg-based propellant is considered to be a promising fuel for underwater propulsion, but the mechanism of the change of the burning rate is unclear. The Mg-based propellant was divided into two parts on the basis of the BDP multi-flame model: large-size oxidizer particle and pseudo-propellant consisting of fine oxidizer and other components, and the micro steady-state combustion model of Mg-based propellant was established. Quantitatively analysis on the gas-phase multi-flame structure was performed, which focused on the effect of pressure, Mg content, and oxidizer particle size on the burning rate. This model was verified by the results of combustion experiments on ammonium perchlorate (AP) /hydroxyl‑terminated polybutadiene (HTPB) composite propellant and Mg-based propellant, and the mean absolute percentage error between the burning rate obtained from the simulation and the experimental measurements was less than 5%. Results indicated that the flame structure of Mg-based propellant exhibited typical BDP flame characteristic. As pressure increased from 1 MPa to 4 MPa, the premixed AP flame and the preliminary diffusion flame were closer to the burning surface, which enhanced the heat feedback. And accordingly, the burning rate raised from 5.93 mm/s to 9.79 mm/s. Mg content mainly affect the combustion process of the pseudo-propellant. The premixed flame above the pseudo-propellant gradually disappeared as the Mg content increased from 15% to 63%, which led the burning rate to decrease from 17.45 mm/s to 7.83 mm/s. AP particle size affected the effectiveness of the preliminary diffusion flame on the burning surface and resulted in a change in the burning rate. These findings can provide theoretical guidance for the design of Mg-based propellant formulations.

The Effects of Cl− and Selected Deoxidizers on the High-Temperature Corrosion Electrochemistry of Alloy 690 in Nuclear Steam Generator Water

The heat transfer tube in a steam generator serves as a critical heat exchange component in the primary and secondary loops of pressurized water reactor (PWR) nuclear power plants. The corrosion resistance of the heat transfer tube material directly influences the longevity of PWR nuclear power plants. This study investigated the electrochemical corrosion properties of 690 alloy (UNS N06690) in a simulated secondary water environment of PWR, focusing on different chloride ion concentrations and combinations of deoxidizers. The findings reveal a gradual decrease in the corrosion potential of 690 alloy, accompanied by an increase in self-corrosion current and a progressive reduction in the passivation range, ultimately leading to its disappearance as chloride ion concentration rises from 0 µg/L to 500 µg/L. Moreover, the impedance value of the inner film exhibits a declining trend with an increase in chloride ion concentration. Conversely, the resistance value of the outer film remains relatively stable while the size and spacing of oxide particles on the surface of the 690 alloy continuously increase. This observation suggests that chloride ions primarily influence the formation of the inner passivation film, which in turn determines the corrosion resistance of the 690 alloy. Notably, the performance of the 690 alloy is similar when the deoxidizer combination is ammonia (NH3) + erythorbic acid (ERA) or NH3 + hydrazine (N2H4), demonstrating the ability to form a relatively complete passivation film and exhibit improved corrosion resistance compared to NH3+N-isopropyl hydroxylamine, additionally, when the deoxidizer combination is NH3+N2H4, the 690 alloy exhibits lower self-corrosion current density across different chloride ion concentrations, indicating enhanced corrosion resistance.

Mn-doped Sequentially Electrodeposited Co-based Oxygen Evolution Catalyst for Efficient Anion Exchange Membrane Water Electrolysis.

Designing high-performance and durable oxygen evolution reaction (OER) catalysts is important for green hydrogen production through anion exchange membrane water electrolysis (AEMWE). Herein, a series of Mn-doped Co-based OER catalysts supported on FeOxHy (FCMx) are presented to enhance the OER activity. Mn doping effectively reduces the size of the Co oxide particles, thereby augmenting the active surface area. Moreover, Mn doping induces the creation of oxygen vacancies, leading to an efficient structural conversion during the OER, which is confirmed via in situ Raman spectroscopy. Under optimal conditions, the catalyst exhibits an overpotential of 234.4 mV at 10 mA cm-2 and a Tafel slope of 37.2 mV dec-1 under half-cell conditions. The AEMWE single-cell system demonstrates a current density of 1560 mA cm-2 at 1.8 V at 60 °C with a degradation rate of 0.4 mV h-1 for 500 h at 500 mA cm-2. Our development of a robust OER catalyst represents notable progress in the field of nonprecious-metal water electrolysis, marking a step toward cost-effective green hydrogen production.

Silicon oxide particles size evolution during CVD graphene growth on Cu substrates

Chemical vapor deposition (CVD) on metal substrates is presently the remarkably route for the synthesis of high-quality continuous graphene films at a large scale. Whereas, during the thermal processing procedure in the quartz tube, the formation of silicon oxide particles would degrade the performance of graphene. To better understand the origin of these particles , a series of CVD graphene growth experiments with were conducted on the Cu substrates. In this paper, we investigated the main component and morphology of the particles by X-Ray photoelectron spectroscopy (XPS), energy dispersive spectrometry (EDS) measurement in scanning electron microscopy (SEM) and revealed that the silicon oxide particles gradually increased in diameter across the graphene films on the Cu surface, which was found to be correlated with the working time of the quartz products. Raman spectroscopy was also applied to prove the drawback consequence of the contamination on the quality of the CVD graphene film. To mitigate this issue, we further propose a modification of the CVD system that a coaxial alumina or BN tube inside the quartz tube to screen the contaminants bringing about improved graphene growth.

Particle size dependence of nanoclustered ceria abrasives on surface activity and chemical mechanical planarization performance

The particle size of cerium oxide (ceria) abrasives plays a crucial role in the design and development of advanced self-stopping slurries for the chemical mechanical planarization (CMP) process in semiconductor device manufacturing. However, a lack of ceria nanoparticles (NPs) with a narrow size distribution and uniform shape poses challenges in investigating the fundamental principles of the relationship between abrasive size and CMP performance. In this study, we thoroughly investigated the effect of ceria NP size on the removal rate (RR) of silicon oxide using uniform-sized nanoclustered (NC) ceria NPs with three diameters: 51.4 nm (NC51), 68.6 nm (NC69), and 108.0 nm (NC108). While all three types of ceria NPs shared a crystallinity of ∼ 70.6 %, they exhibited distinct physicochemical characteristics. As the particle size decreased, the specific surface area and chemical activity (i.e., Ce3+/Ce4+) increased by 155 % and 69 %, respectively. In the CMP process, where direct contact between the abrasives and wafer occurs, the abrasive size influences CMP performance. Experimentally, NC51 achieved the highest RR among the three slurries, along with complex size-dependent contact properties and chemical activities. These experimental results offer significant insights into precise semiconductor manufacturing in a practical manner.

The Influence of Copper Oxide Particle Size on the Properties of Epoxy Resin

This study examines the relationship between the size of copper particles and the properties of epoxy resin. Epoxy resin is a type of thermosetting resin commonly used as a matrix in polymer matrix composite materials reinforced with glass or carbon fibers. As part of this study, three microscale and two nanoscale composite samples modified with copper oxide particles of varying sizes were produced. This study included mechanical property tests such as static tensile tests, static bending tests, and impact tests. The results of the strength tests were compared to modeling results. Additionally, an accelerated thermal aging process was conducted to determine the impact of external conditions on the behavior of the produced composites. This study concluded with an analysis of thermal conductivity. The test results revealed that the size of the copper particles significantly impacted the tested properties. The composites with copper oxide particles on the nanoscale demonstrated the best results. These composites have promising applications in the automotive and aviation industries due to their strength, resistance to external factors, and increased thermal conductivity, suggesting their potential for producing materials that effectively dissipate heat.

Synthesis and evaluation of novel Cu-based adsorbent-containing catalysts for CO2 hydrogenation to methanol and value-added products

In this work, sequential incipient wetness impregnation method was used to synthesize Cu/Al2O3, Cu/Na2O/Al2O3 and Cu/CaO/Al2O3 catalysts in different compositions for CO2 conversion to value-added products. Synthesized catalysts were characterized using various analytical techniques and their performances for CO2 catalytic conversion were tested in a high-pressure packed bed reactor under reaction conditions of P = 60 bars, T = 300 °C, and H2/CO2 = 3. The obtained results revealed that the type of adsorbent had a significant impact on CO2 conversion, with CaO-containing catalyst being more efficient for methanol selectivity. Increased Cu content from 10 wt% to 30 wt% with fixed CaO content of 10 wt% resulted in a small increase in CO2 conversion where the highest CO2 conversion of 16.44% and the highest methanol selectivity (17.75%) were obtained for catalyst containing 20 wt% of copper. The best performing catalyst was further promoted using 0.5 wt% Rh promoter which improved both methanol selectivity and space time yield to 23.2% and 0.08 gMeOHgcat−1h−1, respectively. The comparative high performance of the Rh-promoted catalyst was attributed to smaller metal oxide particle size with uniform dispersion, presence of effective hydrogen spill over, moderate basic sites, surface defects and presence of induced copper species.

First-in-human controlled inhalation of thin graphene oxide nanosheets to study acute cardiorespiratory responses

Graphene oxide nanomaterials are being developed for wide-ranging applications but are associated with potential safety concerns for human health. We conducted a double-blind randomized controlled study to determine how the inhalation of graphene oxide nanosheets affects acute pulmonary and cardiovascular function. Small and ultrasmall graphene oxide nanosheets at a concentration of 200 μg m−3 or filtered air were inhaled for 2 h by 14 young healthy volunteers in repeated visits. Overall, graphene oxide nanosheet exposure was well tolerated with no adverse effects. Heart rate, blood pressure, lung function and inflammatory markers were unaffected irrespective of graphene oxide particle size. Highly enriched blood proteomics analysis revealed very few differential plasma proteins and thrombus formation was mildly increased in an ex vivo model of arterial injury. Overall, acute inhalation of highly purified and thin nanometre-sized graphene oxide nanosheets was not associated with overt detrimental effects in healthy humans. These findings demonstrate the feasibility of carefully controlled human exposures at a clinical setting for risk assessment of graphene oxide, and lay the foundations for investigating the effects of other two-dimensional nanomaterials in humans. Clinicaltrials.gov ref: NCT03659864.