Oxide Microparticles Research Articles

Simultaneous incorporation of gallium oxide and tantalum microparticles into micro-arc oxidation coating of titanium possessing antibacterial effect and stimulating cellular response.

Orthopedic implants with both osteogenesis and antibacterial functions are particularly promising for bone repair and substitutes. In this study, a micro-arc oxidation (MAO) coating containing titanium dioxide (TiO2), gallium oxide (Ga2O3) and tantalum oxide (Ta2O5) on the titanium surface (MGT) was fabricated by dispersing Ga2O3 and Ta microparticles in the electrolyte. The results showed that the simultaneous incorporation of Ga2O3 and Ta microparticles into the MAO coating resulted in optimized surface performance (e.g., micro-topography, roughness, wettability, surface energy, and protein absorption) of MGT compared with pure titanium (pTi). In addition, MGT exhibited outstanding corrosion resistance owing to the presence of both Ga2O3 and Ta microparticles, which exhibit excellent corrosion resistance and their microparticles were incorporated into the micropores of the coating. Moreover, MGT with good cytocompatibility and optimized surface resulted in improved cellular responses (e.g., proliferation and osteogenic differentiation) of rat bone mesenchymal stem cells, which was attributed to Ta microparticles with outstanding osteogenic bioactivity. Furthermore, the excellent antibacterial effect of MGT was attributed to the slow release of Ga3+ from the coating. Thus, the simultaneous incorporation of Ga2O3 and Ta microparticles into the MAO coating of MGT exhibited excellent cytocompatibility, osteogenic bioactivity, antibacterial functions, and corrosion resistance, suggesting that MGT possesses great potential for bone repair applications.

Certification of the First Uranium Oxide micro-particle reference materials for Nuclear Safety and Security, IRMM-2329P and IRMM-2331P

Certification of the First Uranium Oxide micro-particle reference materials for Nuclear Safety and Security, IRMM-2329P and IRMM-2331P

Functionalized zinc oxide microparticles for improving the antimicrobial effects of skin-care products and wound-care medicines.

ZnO is an important component in skin-protection products and wound-care medicines. However, ZnO's antibacterial activity is moderate. We developed two types of ZnO microparticles loading with phthalocyanine-type photosensitizers (ZnO/PSs) introducing the photodynamic effects. These photosensitive ZnO microparticles exhibited long-term while moderate antimicrobial effects by continuously releasing Zn2+ ions. The antimicrobial efficacies were remarkably enhanced by triggering the photodynamic antimicrobial effects. Compared to the sole ZnO which showed non-measurable antimicrobial activity at a concentration of 10mg/L, both ZnO/PSs demonstrated antimicrobial rates ranged 99%-99.99% against Escherichia coli, normal and drug-resistant Staphylococcus aureus. In a dorsal wound infection mouse model, treatment with ZnO/PSs significantly accelerated the wound recovery rates. ZnO/PSs promoted wound healing by a dual effect: 1) the release of Zn2+ ions from ZnO facilitating tissue remodeling; 2) the photodynamic effect efficiently eliminates pathogens avoiding infection. Notably, ZnO/PSs inherited the high biosafety of ZnO without causing noticeable toxicity against erythrocyte and endothelial cells. This study not only provides a highly safe and efficient antimicrobial ZnO material for skin cares and wound modulations, but also proposes a strategy to functionalize ZnO materials.

Exploration of reduced graphene oxide microparticles as electrocatalytic materials in vanadium redox flow batteries

Augmenting reaction rates on porous carbon electrodes is critical for reducing the cost of all-vanadium redox flow batteries (VRFBs). To this end, reduced graphene oxide (rGO) based carbons hold promise, demonstrating high specific surface area, chemomechanical stability, and electrochemical activity. While initial efforts have shown that rGOs can enhance VRFB performance, the range of unique processing conditions leads to a collection of materials with disparate elemental composition and porous structure, thus obscuring performance-determining characteristics behind redox reactions and frustrating general design principles. Here, we generate rGO electrocatalysts of nearly identical chemical composition but different textures (i.e., surface area and pore structure) by varying the drying step in the graphene synthesis (i.e., vacuum-drying vs. carbon dioxide critical point drying). We apply spectroscopic and electrochemical techniques on the synthesized rGOs, observing a three-fold increase in BET surface area using critical point drying. We subsequently decorate carbon felt electrodes – both pristine and thermally activated – with rGO microparticles via a flow deposition procedure, and evaluate their performance and durability in a VRFB cell. The synthesis approach and findings described in this work inform and complement efforts to advance the material science and engineering of rGO electrocatalysts.

Nephrotoxicity of nickel nano and microparticles in rat- a comparative, time dependent study with special reference to antioxidant defence system

A comparative and time dependent study on the effects of nickel oxide nano and nickel oxide microparticles (5 mg/kg body weight) each, has been performed in the kidney of male Wistar rats at two intervals of 15 and 30 days. Morphological, functional changes and effects on antioxidant enzymes in the kidney were studied. Exposure to both, NiONPs and NiOMPs significantly enhanced the generation of reactive oxygen species viz. malondialdehyde, hydrogen peroxide and nitric oxide in rat kidney. However, increase was higher in NiONPs treated rats than NiOMPs treated rats. Diminished values for reduced glutathione and enzymes, that is, superoxide dismutase, glutathione peroxidise and catalase confirmed the role of oxidative stress in NiONPs induced nephrotoxicity. Increased oxidative DNA damage and histopathological changes further supported this hypothesis. Present results suggest that nanoparticles of nickel are more toxic to kidney than nickel metal ions. Reactive oxygen species are a critical factor in NiONPs induced renal toxicity in rat.

Structural incorporation of lanthanides (La, Eu, and Lu) into U3O8 as a function of the ionic radius

The International Atomic Energy Agency implements safeguard measures to verify the compliance of Member States to their international legal obligations using nuclear material and technology only for peaceful purposes. These safeguard measures, i.a., include analytical measurements of individual micrometer- and submicrometer particles taken by the IAEA on swipe samples during safeguard inspections at nuclear facilities. To ensure the quality control of the analytical results from particle analysis and to further develop mass spectrometric analysis methods, microparticles with well-defined properties as microparticulate reference materials are required. Therefore, mixed lanthanide/uranium oxide microparticles were produced as a first step towards composite reference materials with small amounts of fission products, Pu or Th. A deep understanding of the incorporation mechanisms of dopants into U3O8 structure is essential in this regard. Therefore, bulk-scale comparison materials were produced and doped with lanthanides by co-precipitation methods and systematically investigated by TG, XRD, and Raman. These results will be integrated into the particle production process to design well-defined microparticulate mixed-oxide reference materials.Graphical abstract

Occurrence of SiC and Diamond Polytypes, Chromite and Uranophane in Breccia from Nickel Laterites (New Caledonia): Combined Analyses

Different techniques have been combined to identify the structure and the chemical composition of siliceous breccia from a drill core of nickel laterites in New Caledonia (Tiebaghi mine). XRD analyses show quartz as a major phase. Micro-Raman spectroscopy confirmed the presence of reddish microcrystalline quartz as a major phase with inclusion of microparticles of iron oxides and oxyhydroxide. Lithoclasts present in breccia are composed of lizardite, chrysotile, forsterite, hedenbergite and saponite. The veins cutting through the breccia are filled with Ni-bearing talc. Furthermore, for the first time, we discovered the presence of diamond microcrystals accompanied by moissanite polytypes (SiC), chromite (FeCr2O4) and uranophane crystals (Ca(UO2)2(SiO3OH)2.5(H2O)) and lonsdaleite (2H-[C-C]) in the porosities of the breccia. The origin of SiC and diamond polytypes are attributed to ultrahigh-pressure crystallization in the lower mantle. The SiC and diamond polytypes are inherited from serpentinized peridotites having experienced interaction with a boninitic melt. Serpentinization, then weathering of the peridotites into saprolite, did not affect the resistant SiC polytypes, diamond and lonsdaleite. During karstification and brecciation, silica rich aqueous solutions partly digested the saprolite. Again, the SiC polymorph represent stable relicts from this dissolution process being deposited in breccia pores. Uranophane is a neoformed phase having crystallized from the silica rich aqueous solutions. Our study highlights the need of combining chemical and mineralogical analytical technologies to acquire the most comprehensive information on samples, as well as the value of Raman spectroscopy in characterizing structural properties of porous materials.

Rapid Synthesis of High-Entropy Oxide Microparticles.

High-entropy nanoparticles have received notable attention due to their tunable properties and broad material space. However, these nanoparticles are not suitable for certain applications (e.g., battery electrodes), where their microparticle (submicron to micron) counterparts are more preferred. Conventional methods used for synthesizing high-entropy nanoparticles often involve various ultrafast shock processes. To increase the size thereby achieving high-entropy microparticles, longer reaction time (e.g., heating duration) is usually used, which may also lead to undesired particle overgrowth or even densified microstructures. In this work, an approach based on Joule heating for synthesizing high-entropy oxide (HEO) microparticles with uniform elemental distribution is reported. In particular, two key synthesis conditions are identified to achieve high-quality HEO microparticles: 1) the precursors need to be loosely packed to avoid densification; 2)the heating time needs to be accurately controlled to tens of seconds instead of using milliseconds (thermal shock) that leads to nanoparticles or longer heating duration that forms bulk structures. The utility of the synthesized HEO microparticles for a range of applications, including high-performance Li-ion battery anode and water oxidation catalyst. This study opens up a new door toward synthesizing high-entropy microparticles with high quality and broad material space.

Rheological Study of Core−Shell Structured Carbonyl Iron/ 2-D Graphene Oxide Microparticles Suspension with Improved Sedimentation Stability

Rheological Study of Core−Shell Structured Carbonyl Iron/ 2-D Graphene Oxide Microparticles Suspension with Improved Sedimentation Stability

Rheological Study of Core−Shell Structured Carbonyl Iron/ 2-D Graphene Oxide Microparticles Suspension with Improved Sedimentation Stability

Rheological Study of Core−Shell Structured Carbonyl Iron/ 2-D Graphene Oxide Microparticles Suspension with Improved Sedimentation Stability

Epoxy-based composites with enhanced thermal properties through collective effect of different particle size fillers

Taking advantages of excellent adhesion and insulating properties, polymer-based thermal interface materials have been widely used in electrical and electronic industry. However, applications was limited due to the existence of high interfacial resistance and poor mechanical properties resulted from poor dispersion and weak interfacial adhesion of thermal conductive fillers in the polymer matrix. Herein, different sizes of aluminum oxide microparticle was used as thermal conductive fillers to fabricate a series of high thermal conductive epoxy composites, and the effect of fillers loading ratio on the properties of thermal conductive, mechanical, thermal stability was further analyzed. The optimum composite exhibits a high thermal conductivity (1.91 ± 0.02 W·m−1·K−1) at a loading ratio of 1: 2 (20-μm: 70-μm, mass ratio), which is equivalent to a thermal conductivity enhancement of 950% in comparison with pure epoxy resin. The outstanding properties of the as-prepared composite is mainly attributed to the effective conductive network formed by different size fillers that the smaller particles act as a bridge to connect the larger one. This work has proved by Agari model that combining different sizes Al2O3 as fillers is a workable way to obtain composite with high thermal conductivity and it is expected to provide a reliable route for the preparation of thermally conductive composites with different particle sizes.

Organic Template‐Free Synthesis of Mesoporous ZnO Microparticles by Sol‐Gel Method and Low‐Temperature Hydrothermal Treatment

Mesoporous zinc oxide microparticles were synthesized by the sol‐gel method, followed by hydrothermal treatment at three different temperatures (100°C, 120°C, and 140°C), confirming that the method is fast, simple, reproducible, and ecological. To carry out the synthesis of the samples, zinc acetate was used as a precursor and sodium hydroxide as a precipitating agent. From the results obtained, the sample that shows the highest mesoporosity was the one synthesized at a hydrothermal treatment temperature of 140°C, obtaining an average particle size of 5 μm and a pore diameter of 1.7 nm. The importance of the results obtained was that mesoporous xerogel microparticles were obtained without using any type of organic template.

Imaging and Manipulating the Conversion from Single Cuprous Oxide Microparticles to Single Metal Hydroxide Microstructures.

The template-assisted route is an effective avenue for the preparation of core-shell and hollow micromaterials. However, the conversion process is usually characterized by ex situ transmission electron microscopy, limiting the comprehensive understanding of the structure evolution. Here, we use dark-field microscopy (DFM) to visually image the chemical conversion process of Cu2O concave microcubes into metal hydroxide (MHs, M = Co, Ni, and Mn) microstructures at the single-particle level. The details of the conversion process such as early steps in the conversion reaction, intermediate states, and final states are successfully tracked in real time. The in situ DFM experiments clarify that the etching of Cu2O predates the generation of MHs, and the conversion reaction shows significant particle-to-particle variation. Meanwhile, the results also show that experimental parameters dominate the conversion of Cu2O concave microcubes, allowing for the precise manipulation of the reaction degree to obtain Cu2O@Co(OH)2 core-shell microstructures with different shell thicknesses and hollow Co(OH)2 microstructures. The present work offers a direct observation and manipulation of the conversion process of Cu2O microparticles, paving the way for rational design and preparation of various core-shell and hollow micromaterials.

Fabrication of a Selective Sensor Amplification Probe Modified with Multi-Component Zn2SnO4/SnO2 Heterostructured Microparticles as a Robust Electrocatalyst for Electrochemical Detection of Antibacterial Drug Secnidazole.

In this study, we synthesized heterostructured zinc stannate/tin oxide microparticles (ZTO/TO MPs) by a simple coprecipitation method and used them as an effective electrode material for the electrochemical detection of the antibacterial drug secnidazole (SCZ). The as-prepared ZTO/TO MPs were characterized by XRD, Raman, FE-SEM, HR-TEM, EDX, and XPS analyses. The physiochemical studies clearly proved that the fabricated ZTO/TO MPs were formed in a heterostructure phase without other impurities. A glassy carbon electrode modified with the synthesized ZTO/TO MPs showed an excellent and improved electrocatalytic activity in the electrochemical reduction of SCZ. Using differential pulse voltammetry (DPV), an impressive linear calibration range, extending from 0.01 to 193 μM, was observed, coupled with a detection limit of 0.0054 μM and a sensitivity of 0.055 μA/μM. In addition, the ZTO/TO MPs/GCE showed very good selectivity for the detection of SCZ in the presence of a number of biological, inorganic, and structurally related compounds. Finally, the ZTO/TO MPs/GCE was investigated for the analysis of SCZ in human blood serum samples. A very good recovery was obtained when spiking the blood serum with SCZ, highlighting the good applicability of the ZTO/TO MPs/GCE for the electrochemical analysis of SCZ in complex biological samples.

Mechanical and thermal characterization of laminar carbon/epoxy composites modified with magnesium oxide microparticles

AbstractThis paper investigates the effects of magnesium oxide (MgO) microparticles on the mechanical and thermal properties of laminated carbon fiber reinforced polymer composites. The polymer epoxy matrix was modified with 0% (pure), 2 wt%, and 4 wt% MgO fillers. Then the laminar composites were manufactured with the vacuum bag method. The energy absorption capacity and impact strength were determined from the Charpy impact tests, whereas the flexural characteristics were evaluated by conducting three‐point bending experiments. Scanned electron microscopy was used to examine both the dispersion of microparticles and the fracture surface of experimentally tested specimens. Thermal performance of the polymer composites with and without MgO additives was analyzed comparatively by performing the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The decomposition temperatures and glass transition temperatures of the composites were obtained. Approximately 30% increment in impact strength was achieved thanks to the MgO fillers. However, although the flexural strength decreased since the MgO particles caused stress concentration, the flexural modulus was not affected due to the decrease of elongation at break. The TGA and DSC instrumentations showed that the decomposition temperatures increased, and curing behaviors were improved depending upon the MgO content.

Stimulation of Healing of Non-Infected Stagnated Diabetic Wounds by Copper Oxide-Impregnated Wound Dressings.

Background and Objective: Copper, a wide spectrum biocide, also plays a key role in angiogenesis and wound healing. Antibacterial wound dressings impregnated with copper oxide microparticles (COD) have been recently cleared by the U.S. FDA and other regulatory bodies for the treatment of acute and chronic wounds, including diabetic wounds. Our objective was to evaluate the capacity of COD in stimulating the healing of non-infected stagnated wounds in diabetic patients initially treated with standard of care (SOC) dressings. Materials and Methods: The trial was divided into the three following phases: 1–2 weeks of screening, during which the patients were treated with SOC dressings; 4 weeks of treatment, during which the COD was applied twice weekly; and 2 weeks of follow-up, during which the patients were again treated with SOC dressings. The wound conditions and sizes were assessed by clinical evaluation and a wound imaging artificial intelligence system. Results: Following 1 month of COD treatment, there was a clear reduction in the mean wound area (53.2%; p = 0.003), an increase in granulation tissue (43.37; p < 0.001), and a reduction in fibrins (47.8%; p = 0.002). In patients with non-weight-bearing wounds, the reduction in wound size was even more dramatic (66.9%; p < 0.001). Conclusions: The results of this study, showing a statistically significant influence of COD on wound healing of hard-to-heal wounds in diabetic patients, strongly supports the notion that copper oxide-impregnated dressings enhance wound healing directly. Further larger controlled studies should be conducted to substantiate our findings.

In Situ Functionalization of Iron Oxide Particles with Alginate: A Promising Biosorbent for Retention of Metal Ions.

In this study, alginate extracted from marine algae biomass was used for the functionalization of iron oxide particles obtained in situ. This procedure ensured a complete recovery of the alginate from the aqueous solution obtained after extraction and allowed the preparation of a new biosorbent. The obtained iron oxide microparticles functionalized with alginate (Alg-Fe3O4-MPs) were analyzed (FTIR spectrometry, energy dispersive X-ray spectroscopy and scanning electron microscopy), and their biosorptive performance was tested for the removal of Cu(II), Co(II) and Zn(II) ions. The optimal conditions were established as pH = 5.4, adsorbent dosage of 2 g/L, contact time of minimum 60 min and room temperature (23 ± 1 °C). The retention of metal ions was quantitative (99% for Cu(II), 89% for Co(II) and 95% for Zn(II)) when the concentration of metal ions was less than 0.80 mmol M(II)/L. The Langmuir model was found to be the best fitted model for the equilibrium data, while biosorption kinetics followed the pseudo-second order model. Biosorption processes were spontaneous (ΔG0 < 0), endothermic (ΔH0 > 0), and accompanied by an increase in entropy (ΔS0 > 0). The high maximum biosorption capacity of Alg-Fe3O4-MPs and its good regeneration highlight the potential of this biosorbent for applications in decontamination processes.

Controlling Pore Size of Electrospun Vascular Grafts by Electrospraying of Poly(Ethylene Oxide) Microparticles.

Electrospinning has become a popular polymer processing technique for application in vascular tissue engineering due to its unique capability to fabricate porous vascular grafts with fibrous morphology closely mimicking the natural extracellular matrix (ECMs). However, the inherently small pore sizes of electrospun vascular grafts often inhibit cell infiltration and impede vascular regeneration. Here we describe an effective and controllable method to increase the pore size of electrospun poly(ε-caprolactone) (PCL) vascular graft. With this method, composite grafts are prepared by turning on or off electrospraying of poly(ethylene oxide) (PEO) microparticles during the process of electrospinning PCL fibers. The PEO microparticles are used as a porogen agent and can be subsequently selectively removed to create a porogenic layer within the electrospun PCL grafts. Three types of porogenic PCL grafts were constructed using this method. The porogenic layer was either the inner layer, the middle one, or the outer one.

Nano/microparticles in conjunction with microalgae extract as novel insecticides against Mealworm beetles, Tenebrio molitor

The intensive use of insecticides in global agricultural production has attracted much attention due to its many adverse effects on human health and the environment. In recent years, the utilization of nanotechnology has emerged as a tool to overcome these adverse effects. The aim of this work was to test different microparticles (zinc oxide (ZnO MPs) and silicon dioxide microparticles (SiO2 MPs)), and silver nanoparticles (Ag NPs) and to study their toxicity on a model organism, Tenebrio molitor. A comprehensive comparative study, which included more than a thousand mealworms divided into nine separate groups, was conducted. In addition to pure nano/microparticle solutions, the effect of particles mixed with the microalgae extract Chlamydomonas reinhardtii was also observed. Pure Ag NPs and SiO2 MPs resulted in larval mortality of more than 70% compared to that of pure ZnO MPs, in which the mortality rate was approximately 33%. A mixture of the algal extract with zinc oxide microparticles resulted in mortality that was double compared to that observed with pure ZnO MPs. In parallel, atomic absorption spectrometry (AAS) was used to determine the difference in the concentration of trace elements in the bodies of dead and live larvae.

Attributes of oxidative stress in the reproductive toxicity of nickel oxide nanoparticles in male rats.

The nanoparticles of nickel are now being widely used in industrial, commercial, and biomedical applications. In recent years, health safety issues posed by them have aroused concerns among health scientists. The aim of the present study was to investigate the role of oxidative stress in male reproductive toxicity induced by nickel oxide nanoparticles in rats. Male Wistar rats (140-170 g) were administered with nickel oxide nanoparticles (NiONPs) (particles size <30 nm) (5 mg/kg body weight) by gavage for 30 days. Its effects on different parameters, viz., sperm count, motility, and morphology, were investigated. DNA damage in sperms was monitored through comet assay. All these observations indicated a spermicidal effect of NiONPs. Results on lipid peroxidation (MDA, H2O2, and NO) and oxidative stress (GSH, GPx, and catalase) thus studied in testes exhibited adverse effects of NiONPs. Histopathological results on male reproductive organs, viz., testis, epididymis, vas deferens, seminal vesicles, and prostate also demonstrated moderate to severe toxicity. A comparison of these results with those obtained on nickel oxide microparticle (NiOMP)-treated rats showed that NiONPs are more toxic than NiOMPs. Furthermore, NiONPs could create an imbalance between oxidants and antioxidants in the testes. It is concluded that redox imbalance in testes constitutes a major mechanism of NiONP-induced reproductive toxicity.