Oxide Microparticles Research Articles

Analysis of the Structure of the Adsorbed Polymer Layers on the Surfaces of Metal Oxide Microparticles Using Digital Image Processing

The shapes and the sizes of metal oxide particles in polymer-stabilized disperse systems subjected to mechanical activation are considered. The digital processing of images of metal oxide particles is used to determine the parameters of the particles and the adsorbed polymer layers and to find the density change dynamics in an adsorbed layer.

A global metabolomic insight into the oxidative stress and membrane damage of copper oxide nanoparticles and microparticles on microalga Chlorella vulgaris

To compare aquatic organisms’ responses to the toxicity of copper oxide (CuO) nanoparticles (NPs) with those of CuO microparticles (MPs) and copper (Cu) ions, a global metabolomics approach was employed to investigate the changes of both polar and nonpolar metabolites in microalga Chlorella vulgaris after 5-day exposure to CuO NPs and MPs (1 and 10 mg/L), as well as the corresponding dissolved Cu ions (0.08 and 0.8 mg/L). Unchanged growth, slight reactive oxygen species production, and significant membrane damage (at 10 mg/L CuO particles) in C. vulgaris were demonstrated. A total of 75 differentiated metabolites were identified. Most metabolic pathways perturbed after CuO NPs exposure were shared by those after CuO MPs and Cu ions exposure, including accumulation of chlorophyll intermediates (max. 2.4–5.2 fold), membrane lipids remodeling for membrane protection (decrease of phosphatidylethanolamines (min. 0.6 fold) and phosphatidylcholines (min. 0.2–0.7 fold), as well as increase of phosphatidic acids (max. 1.5–2.9 fold), phosphatidylglycerols (max. 2.2–2.3 fold), monogalactosyldiacylglycerols (max. 1.2–1.4 fold), digalactosylmonoacylglycerols (max. 1.9–3.8 fold), diacylglycerols (max. 1.4 fold), lysophospholipids (max. 1.8–3.0 fold), and fatty acids (max. 3.0–6.2 fold)), perturbation of glutathione metabolism induced by oxidative stress, and accumulation of osmoregulants (max. 1.3–2.6 fold) to counteract osmotic stress. The only difference between metabolic responses to particles and those to ions was the accumulation of fatty acids oxidation products: particles caused higher fold changes (particles/ions ratio 1.9–3.0) at 1 mg/L and lower fold changes (particles/ions ratio 0.4–0.7) at 10 mg/L compared with ions. Compared with microparticles, there was no nanoparticle-specific pathway perturbed. These results confirm the predominant role of dissolved Cu ions on the toxicity of CuO NPs and MPs, and also reveal particle-specific toxicity from a metabolomics perspective.

Development of Anti-Aging and Anticorrosive Nanoceria Dispersed Alkyd Coating for Decorative and Industrial Purposes

This study focuses on nano cerium oxide particles as alternative additives in solvent-based alkyd coatings in order to improve anticorrosive and anti-aging properties. The paint samples were formulated with cerium oxide micro and nanoparticles, and the coating quality characteristics were compared with coating formulated with commercial anticorrosive and UV-aging agents. Formulations were prepared with 3 wt % commercial anticorrosive agent as reference material (RP), 3 wt % cerium oxide microparticles (CER1), 3 wt % and 1% cerium oxide nanoparticles (CER2 and CER3), respectively. The basket milling technique with zirconium balls was used for the preparations of coatings and characterizations were performed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and contact angle measurements. Improvement in the anticorrosive properties was proven with electrochemical impedance spectroscopy (EIS) and accelerated salt spray tests based on ISO 4628 Evaluation of Degradation of Coatings. Furthermore, physical and mechanical tests were run according to standard test methods for coatings and reported. Results showed that cerium oxide particles provide anticorrosive, UV defender, and self-cleaning effects, besides excellent physical resistance to alkyd coatings. The impact of cerium oxide nanoparticles was found to be stronger than those of the microparticles.

Partitioning and stability of ionic, nano- and microsized zinc in natural soil suspensions

Batch experiments aimed at solid-liquid distribution of 40 nm engineered zinc oxide nanoparticles (ZnO-NP), microparticles (bulk ZnO), and ionic Zn in ZnSO4 solution were conducted on eight field soil samples of different characteristics to identify how the form of Zn affects its distribution in soil. The concentration of Zn in different size fractions present in supernatant solutions obtained from centrifuged soil suspensions was also measured. The distribution between a liquid and a solid was different for the ionic Zn (ZnSO4) and particulate Zn (ZnO-NP and bulk ZnO). In acidic soil solutions, the partitioning coefficient (KdA) of the ionic Zn was in range of 14.7–15.9 compared to 133.4–194.1 for ZnO-NP and bulk ZnO. The situation was reversed under alkaline conditions resulting in a decreased retention of particulate forms of Zn by the solids, with ZnO-NP showing KdA of 8.5–23.4 compared to 160.0–760.1 of ionic Zn. Soil pH thus appears to be the predominant factor influencing the solid-liquid distribution of Zn in different forms. Even the distribution of Zn in different size fractions is heavily affected by the soil pH, causing dissolution of ZnO-NP and bulk ZnO in acidic soils. In alkaline soils, applied ionic Zn (ZnSO4) remained dissolved. This study shows that ZnO-NP are the most mobile of the three tested forms of Zn in alkaline soils. This may affect the spatial distribution of Zn in soil and potentially increase the effectivity of the application of Zn fertilizer when in nanoparticle form.

Electrochemical properties of Fe2O3/AB based composite electrodes in alkaline solution

To find a suitable material for Fe-air battery anode, Fe2O3 nanoparticles (nm) and microparticles (µm) were used as active materials and Acetylene Black carbon (AB) as additive to prepare Fe2O3/AB composites. The effect of grain size of iron oxide particles and additives on the electrochemical behavior of Fe2O3/AB composite electrodes in alkaline solution have been investigated using cyclic voltammetry (CV), galvanostatic cycling and electrochemical impedance spectroscopy (EIS) measurements. Iron oxide nanoparticles provided better cyclability than iron oxide microparticles. Impedance of electrode increased during cycling but the nm-Fe2O3/AB electrode gave smaller resistance than µm-Fe2O3/AB one. The additives showed strongly effects on the electrochemical behaviors of iron oxide electrodes. The AB additive enhanced the electric conductivity of Fe2O3/AB electrode and thus increased the redox reaction rate of iron oxide while K2S interacted and broke down the passive layer leading to improved cyclability and giving higher capacity for Fe2O3/AB electrodes.

Toxicity assessment of magnesium oxide nano and microparticles on cancer and non-cancer cell lines

Testing of magnesium oxide nanoparticles (MgO NPs) on established cell lines at cellular levels using toxicological endpoints provide valuable information about their adverse effects upon exposure. In vitro toxicity assessment of MgO NPs and their microparticles was carried out at 50, 100, 200 and 400 µg/mL concentrations by using cytotoxicity, genotoxicity, oxidative stress, cellular apoptosis and cellular uptake studies in cancer (HepG2) and non-cancer (NRK 49F) cell lines after 24 h of treatment. IC50 concentration for MgO NPs was found to be > 400 µg/mL in both cell lines after 24 h treatment. A concentration dependent toxicity was noted in genotoxic studies and oxidative stress parameters. A significant increase in the comet tail DNA was recorded at 200 and 400 µg/mL concentrations of MgO NPs when compared with controls in HepG2 and NRK 49F cells. Exposure to MgO NPs led to an increase in the generation of reactive oxygen species (ROS) in both the cell types. Genotoxicity results were further supported by apoptotic analysis. MgO particles were found adhered to the cell membrane when assayed by ICP-OES. The results of this study showed that the MgO NPs were toxic at high concentrations only. Furthermore, MgO NPs are more toxic to cancerous cells compared to non-cancerous cells. ROS mediated genotoxicity was observed when treated with MgO NPs. The current study adds to the information on MgO particles. The results of this investigation may help in advancement of understanding of toxicological nature of MgO NPs and aid in their use.

Synthesis of manganese–tin oxide microparticles by the solvothermal method and study of application as a catalyst and additive

ABSTRACT Manganese–tin bimetallic oxide (MnSnO3) is synthesized by the solvothermal approach using manganese acetate and stannic chloride as precursors and urea as a precipitating agent in an aqueous medium. The crystallinity, purity and lattice parameters of the product are analysed by the X-ray diffraction analysis. The morphology of the product is analysed with the help of a scanning electron microscopy. The synthesized product is used as a fuel additive and catalyst. Synthesized MnSnO3 is used as a catalyst for the degradation of an organic dye Congo red in the aqueous medium. Catalytic degradation is monitored at different concentrations of the catalyst and hydrogen peroxide. Moreover, the role of MnSnO3, as an additive in diesel fuel, is studied. The efficiency of the modified fuel is analysed by studying the different parameters such as flash point, fire point, cloud point, pour point, calorific values and specific gravity. The values of these parameters change significantly by changing the dosage of the additive.

Effects of Acute Moderate Exercise on Nitric Oxide and Endothelial Microparticles in Patients with Hypertension

Effects of Acute Moderate Exercise on Nitric Oxide and Endothelial Microparticles in Patients with Hypertension

Assembling a magnetometer for measuring the magnetic propertiesof iron oxide microparticles in the classroom laboratory

A compact magnetometer, simple enough to be assembled and used by physics instructional laboratory students, is presented. The assembled magnetometer can measure the magnetic response of materials due to an applied field generated by permanent magnets. Along with the permanent magnets, the magnetometer consists of two Hall effect-based sensors, a wall-adapter dc power supply to bias the sensors, a handheld digital voltmeter, and a plastic ruler. Here, a project-based exercise is described, where the objectives are as follows: (i) assemble the magnetometer, (ii) measure the magnetic response of the iron oxide microparticle sample, and (iii) obtain the magnetization of the sample from the measurements.

The improvement of cell infiltration in an electrospun scaffold with multiple synthetic biodegradable polymers using sacrificial PEO microparticles.

Electrospinning is a fabrication technique to generate three dimensional scaffolds with a fiber structure that imitates extracellular matrix for tissue engineering constructs. The versatile characteristics of the electrospinning process yields designer scaffolds made of biodegradable polymers or natural proteins with controllable fiber diameters, biodegradation, and mechanical properties. A limitation of conventional electrospun scaffolds is the dense fiber packing with low porosity that leads to poor cell infiltration. Electrospraying sacrificial polyethylene oxide (PEO) microparticles in combination with electrospun scaffolds are a method to increase porosity. We report the effectiveness of electrospraying PEO microparticles to increase porosity of the most commonly used biodegradable polymers: polyglycolic acid (PGA), poly (lactic-co-glycolic) acid (PLGA), and polycaprolactone (PCL). The biodegradable polymer electrospun scaffolds with the sacrificial PEO microparticles were found to have improved cell proliferation and infiltration with human fibroblasts compared to conventional electrospun scaffolds. The mechanical properties of the more robust PGA and PLGA had minor changes, but the more elastic PCL was observed to be weaker and less stiff after the removal of the PEO microparticles. Therefore, this study found PEO microparticles can increase porosity and cell infiltration with stable mechanical properties for a wide variety of biodegradable polymers in electrospun scaffolds.

Lead Oxide Microparticles Coated by Ethylenediamine-Cross-Linked Graphene Oxide for Lithium Ion Battery Anodes

Lead-based anodes in Li-ion batteries have potential in stationary storage applications, due to their high theoretical volumetric energy density. In this study, the cycle performance of PbO was improved by coating it with a network of graphene oxide sheets, cross-linked by ethylenediamine. The carbon coating reduced electrode capacity degradation from 0.42% to 0.22% per cycle over 200 cycles, increased Coulombic efficiency from 96% to 99%, and increased the accessible capacity of the electrodes through improved electrical connectivity. This low-temperature carbon coating technique is potentially advantageous to other metastable and low-melting electroactive materials.

High Sensitive Immunoelectrochemical Measurement of Lung Cancer Tumor Marker ProGRP Based on TiO₂-Au Nanocomposite.

Progastrin-releasing peptide (ProGRP), which is known to be highly specific and sensitive to small cell lung cancer (SCLC), has been proven to be a valuable substitute for neuron-specific enolase in SCLC diagnostics and monitoring, especially in its early stages. The detection of ProGRP levels also facilitates a selection of therapeutic treatments. For the fabrication of our proposed biosensor, titanium (IV) oxide microparticles were first used, followed by dispersing gold nanoparticles into chitosan and immobilizing them onto a carbon paste electrode (CPE) surface. The developed immunosensor exhibits a much higher biosensing performance in comparison with current methods, when it comes to the detection of ProGRP. Therefore, the proposed CPE/TiO2/(CS+AuNPs)/anti-ProGRP/BSA/ProGRP is excellent for the development of a compact diagnostics apparatus.

Size-controlled Preparation of Alkylamine-stabilized Copper Fine Particles from Cupric Oxide (CuO) Micro-particles

ABSTRACTSize control of copper fine particles is highly important for their application for conductive materials. In this study, easy size tuning of the copper fine particles coated by n-hexylamine was achieved via controlling the ratio of n-hexylamine and the precursor CuO. The obtained particles were stable and had a hydrophobic surface. TG-DTA measurement revealed the formation of thin layer of n-hexylamine on the particles.

In vitro induction of odontogenic activity of human dental pulp stem cells by white Portland cement enriched with zirconium oxide and zinc oxide components.

Background. The aim of this in vitro study was to investigate the effect of zinc oxide (ZnO) and zirconium oxide (ZrO2) microparticles (MPs) and nanoparticles (NPs) in combination with white Portland cement (WPC) on odontogenic capacity of human dental pulp stem cells over a period of 21 days. Methods. Synthesized ZnO and ZrO2 particles were characterized using scanning electron microscopy and transmission electron microscopy. The viability of human dental pulp stem cells was measured by a 3-(4,5-dimethylthiazolyl-2-yl)-2,5- diphenyltetrazolium bromide assay at 7-, 14- and 21-day intervals after seeding on WPC disks enriched with ZnO and ZrO2 MPs and NPs. Odontogenic potential of ZnO and ZrO2 particles in combination with WPC was investigated by alkaline phosphatase (ALP) activity and ionized calcium level of supernatant culture media at different time intervals. Data were analyzed using one-way ANOVA and post hoc Tukey tests. Results. All the materials exhibited cell viability over a 21-day period, except for WPC with ZnO NPs on day 7, although it was not statistically significant (P>0.05). The ALP activity and ionized calcium level increased in all the groups compared to the control group (P<0.05). ZnO NPs had superior effect on odontogenic activity and calcium ion release compared to ZnO MPs (P=0.046). There was no significant difference between ZrO2 MPs and NPs in odontogenic activity (P>0.05). Conclusion. WPC enriched with ZnO and ZrO2 increased ALP activity and calcium ion release of human dental pulp stem cells over a period of 21 days in vitro.

Comparison on Properties and Efficiency of Bacterial and Electrospun Cellulose Nanofibers

Cellulose nanofibers were prepared from bacterial synthesis (bottom up approach) and electrospinning technique (top down method). Significant differences are noticed between bacterial (BC) and electrospun cellulose nanofibers (EC) in their properties such as diameter of fibers, decomposition temperature, surface area and mechanical strength. Filtration of cadmium oxide micro-particles and Staphylococcus aureus bio-aerosol using BC and EC was prominently influenced by their properties. Furthermore, in-vitro release of sparingly water soluble drug, ibuprofen was carried out using BC and EC as carrier materials.

Bioinspired and bristled microparticles for ultrasensitive pressure and strain sensors

Biological sensory organelles are often structurally optimized for high sensitivity. Tactile hairs or bristles are ubiquitous mechanosensory organelles in insects. The bristle features a tapering spine that not only serves as a lever arm to promote signal transduction, but also a clever design to protect it from mechanical breaking. A hierarchical distribution over the body further improves the signal detection from all directions. We mimic these features by using synthetic zinc oxide microparticles, each having spherically-distributed, high-aspect-ratio, and high-density nanostructured spines resembling biological bristles. Sensors based on thin films assembled from these microparticles achieve static-pressure detection down to 0.015 Pa, sensitivity up to 121 kPa−1, and a strain gauge factor >104, showing supreme overall performance. Other properties including a robust cyclability >2000, fast response time ~7 ms, and low-temperature synthesis compatible to various integrations further indicate the potential of this sensor technology in applying to wearable technologies and human interfaces.

Clean Block Copolymer Microparticles from Supercritical CO2: Universal Templates for the Facile and Scalable Fabrication of Hierarchical Mesostructured Metal Oxides.

Metal oxide microparticles with well-defined internal mesostructures are promising materials for a variety of different applications, but practical routes to such materials that allow the constituent structural length scales to be precisely tuned have thus far been difficult to realize. Herein, we describe a novel platform methodology that utilizes self-assembled block copolymer (BCP) microparticles synthesized by dispersion polymerization in supercritical CO2 (scCO2) as universal structure directing agents for both hydrolytic and nonhydrolytic sol-gel routes to metal oxides. Spherically structured poly(methyl methacrylate- block-4-vinylpyridine) (PMMA- b-P4VP) BCP microparticles are translated into a series of the corresponding organic/inorganic composites and pure inorganic derivatives with a high degree of fidelity for the metal oxides TiO2 and LiFePO4. The final products are comprised of particles close to 1 μm in size with a highly ordered internal morphology of interconnected spheres between 20-40 nm in size. Furthermore, our approach is readily scalable, enabling grams of pure or carbon-coated TiO2 and LiFePO4, respectively, to be fabricated in a facile two step route involving ambient temperature mixing and drying stages. Given that both length scales within these BCP microparticles can be controlled independently by minor variations in the reagent quantities used, the present general strategy could represent a milestone in the design and synthesis of hierarchical metal oxides with completely tunable dimensions.

Electrospinning of PAN and composite PAN-GO nanofibres

Purpose: The aim of this study was to present the influence of used reinforcement phase – graphene oxide (GO) and the electrospinning process parameters (the distance between the nozzle and collector) on the morphology and the structure of the obtained composite PAN-GO nanofibres. Design/methodology/approach: To produce pure polymer nanofibers, a 10% (wt.) electrospinning solution the polyacrylonitrile (PAN) was dissolved in N, N-dimethylformamide (DMF). The spinning solution used for electrospinning PAN-GO composite fibres was made by dissolving the PAN in a mixture of GO and DMF. By changing the configuration of the distance between the nozzle and collector (10 and 20 cm) and maintaining the remaining parameters (solution flow rate and potential difference between the electrodes), four samples in the form of nanofibrous mats were made. In order to identify the structure and morphology of the reinforcing phase, X-ray microanalysis (EDX) and scanning electron microscopy (SEM) were performed. In addition, the structure of graphene oxide microparticles was investigated by a Raman spectrometer. In order to determine the influence of the distance between the nozzle and the collector used in the electrospinning process and the addition of the reinforcing phase to the morphology and structure of the obtained PAN polymer nanofibres and PAN-GO composite nanofibres, they were examined using SEM. The analysis of the chemical composition of PAN and PAN-GO fibres was carried out using X-ray microanalysis. Findings: The morphology and structure analysis indicated that polymer nanofibres PAN for both the distances between the nozzle and the collector show no structural defects and presented same diameter over the entire length of the fibre. Nanofibres with the addition of GO obtained at both distances between the electrodes, showed defects in the form of beads. In addition, it was observed that with increasing distance between the nozzle and collector the diameter of obtained nanofibres is smaller for both pure PAN and composite PAN-GO samples. Research limitations/implications: The paper is the basis for further research in the field of the use of PAN-GO composite nanofibres as water purification materials. Originality/value: The electrospinning method can be an alternative to conventional methods for the production of filtering membranes due to the ease of carrying out the process and the fact that a material with a high specific surface area is obtained.

Peanut shaped titanium oxide micro-particles achieved by cathode plasma electrolysis and their electrorheological characteristics

Peanut shaped TiO2 micro-particles were prepared by using the huge energy of the plasma and controlling the Ti(SO4)2 concentrations in aqueous solutions via a one-step method, cathode plasma electrolysis. The morphology and structure of the micro-particles were characterized, and the tiny nanostructures about 3–10 nm were obtained on their surface, which obviously increased their surface roughness and specific surface area. These peanut shaped TiO2 particles with nanostructures on their surface were considered to be formed by the collision of two molten TiO2 particles and then the sharply cooling in Ti(SO4)2 solution. Most of all, the electrorheological (ER) behaviors of the peanut shaped TiO2 micro-particles were characterized using a rotational rheometer. Compared with the traditional TiO2 powders, the better ER effect of the peanut shaped micro-particles was attributed to their unique shape and special surface nanostructures.

Uranium oxide microparticle suspensions for the production of reference materials for micro-analytical methods

To support the nuclear safeguards particle analysis, a method was developed to produce micrometer-sized uranium oxide microspheres with a known uranium content and isotope ratio, which are intended to be characterized as certified reference material. To simplify handling of the produced particles, the collected particles have been transferred into ethanol suspensions. In addition to a demonstration of the suitability and new capabilities of such particle suspensions, such as the preparation of particle mixtures, the stability of the particles has been investigated and demonstrated with regard to dissolution and isotopic exchange.