Concentration Of Microparticles Research Articles

Open cultivation of microorganisms in water‐in‐oil Pickering emulsions stabilized by stearate microparticles

AbstractWe report a long‐term open cultivation of model microorganisms in water‐in‐oil (W/O) Pickering emulsions stabilized by food‐grade calcium stearate microparticles without contamination. W/O Pickering emulsions were successfully prepared using calcium stearate microparticles in tetradecane. Effect of microparticle concentration on the emulsion's Sauter mean diameter was investigated at various hold‐ups. As a result, the smaller the hold‐up, the smaller was the change in Sauter mean diameter due to the microparticle concentration. It was found that Sauter mean diameter of the emulsions was almost constant for 2 months. Model microorganisms Escherichia coli and Bacillus subtilis solubilized in the emulsion were stationary cultivated in the air‐exposed state. The viable cell ratio temporarily decreased at the beginning of cultivation but then increased continuously with cultivation time after 28 days. Furthermore, there were no contamination for 28 days in the air‐exposed state of the emulsion solution containing a culture medium without microorganisms. It was also shown that the growth rate of the microorganisms in the emulsion system is significantly lower than those in conventional cultivation systems. Thus, the calcium stearate Pickering W/O emulsion system is suitable for a long‐term “open” cultivation of microorganisms without the use of any special equipment such as a jar‐fermenter.

Floods enhance the abundance and diversity of anthropogenic microparticles (including microplastics and treated cellulose) transported through karst systems

Microplastics (plastics <5 mm) are emerging contaminants that have been detected in virtually all environments. While microplastic research in terrestrial surface waters has been proliferating, microplastic contamination in subsurface environments remains understudied. Karst terrains may be particularly susceptible to microplastic pollution because the presence of large dissolution openings allows fast transport of water through these systems, facilitating the introduction of surface contaminants into subsurface habitats. Furthermore, few studies address the prevalence and movement of microparticles composed of semisynthetic and modified natural materials, despite their known ecotoxicity. Our study therefore aims to identify anthropogenic (i.e., synthetic, semisynthetic, and treated natural) microparticle extent, sourcing, and transport in subsurface karst environments. To do so, we examined a cave spring under variable flow conditions, finding that anthropogenic microparticles were present in all samples and were most frequently fibrous and clear. The mean anthropogenic microparticle concentration during baseflow was 9.2 counts/L but increased up to 81.3 counts/L during floods, indicating their enhanced mobilization when relatively dilute, acidic, and sediment-rich event water entered the cave. These results suggest that anthropogenic microparticles may originate from surface recharge or sediment resuspension within the cave. When we analyzed a subset of microparticles with Fourier transform infrared spectroscopy (FTIR), we found that cellulose of known (i.e., dyed) and suspected (i.e., clear) anthropogenic origin was the most abundant material type. We nevertheless confirmed the presence of microplastics in the cave stream under all flow conditions, with the most common polymer being polyethylene. Both the concentrations and relative fractions of microplastics were higher during floods compared to baseflow, indicating their increased transport during high flow events. We also observed that microplastic polymer types diversified as discharge increased. Our study gives new insight into how anthropogenic microparticle contamination is transported through karst landscapes that can help inform debris mitigation strategies to protect ecosystems and water resources.

ქ. რუსთავის და მიმდებარე ტერიტორიის ატმოსფეროში PM2.5-ის გავრცელების გამოკვლევა

The distribution of PM2.5 in the atmosphere of the city of Rustavi and its environs was studied under eastern background light air, gentle and fresh breeze. It has been established that the maximum concentrations of PM2.5 in the atmosphere of Rustavi are almost always higher than the corresponding maximum allowable concentrations. The trend of hourly changes in concentrations showed that during the day the concentration of microparticles reaches its maximum in the various period of the day. Numerical modeling of the local distribution of microparticles carried out in the city of Rustavi during background easterly light air, gentle and fresh breeze showed us that the change in the daily regime of relief and temperature with eastern light air in Rustavi for 12 hours leads to a complex and significant change in the wind speed directed to land. It forms on the territory of Kvemo Kartli the opposite current of the background wind, which corresponds to the horizontal circular wind circulation. The value of circulation gradually decreases with increasing height and in the boundary layer of the atmosphere (600 m above the earth's surface) has the form of a wave disturbance. the picture obtained with an average background east wind is qualitatively similar to the field obtained with a background light air, and with a fresh breeze, in contrast to the case of a light air and gentle breeze, the pollution zone covers most of the simulation zone.

The effect of liquid bound by microparticles (ions) on the membrane selectivity

Notion “critical concentration” was introduced for membrane processes, and a formula was proposed to calculate it. A mathematical problem of steady-state convective-diffusive mass transfer within the layer of concentration polarization was formulated and exactly solved, taking into account the hydration of microparticles (ions). For numerous examples, analyses were performed to estimate the effect of hydration and mass transfer parameters on the concentration of suspended microparticles at the membrane surface and its selectivity for uniform impurity.

Magnetizable Membranes Based on Cotton Microfibers, Honey, Carbonyl Iron, and Silver Nanoparticles: Effects of Static Magnetic Fields and Medium-Frequency Electric Fields on Electrical Properties

In this work, we present the manufacturing process of magnetizable membranes based on cotton microfibers, honey, carbonyl iron, and three different concentrations of silver microparticles. Each membrane is used as a dielectric material for the fabrication of electrical devices. By using the plane capacitor method, the electrical capacitance and dielectric loss tangent are measured in a medium-frequency alternating field superimposed on a static magnetic field. From the obtained data, the time constants of the devices, the components of complex dielectric permittivity, and the electrical conductivity of the membranes as a function of the electric field frequency and magnetic flux density can be extracted. The results show that the obtained membranes can be useful for the fabrication of low-cost and environmentally friendly magneto-active membranes that are required for various technical and biomedical applications.

MPs-ACT, an Assay to Evaluate the Procoagulant Activity of Microparticles.

The procoagulant effect of microparticles (MPs) contributes to hypercoagulability-induced thrombosis. We provide preliminary findings of the MPs-Activated Clotting Time (MPs-ACT) assay to determine the procoagulant activity of MPs. MPs-rich plasma was obtained and recalcified. Changes in plasma viscoelasticity were evaluated and the time to the peak viscoelastic changes was defined as the MPs-ACT. MPs concentration was measured by flow cytometry. Coagulation products produced during plasma clotting were identified by fibrin and fibrinopeptide A. MPs were prepared in vitro and added to standard plasma to simulate pathological samples. In addition, reproducibility and sensitivity were evaluated. We confirmed the linear relationship between MPs-ACT and MP concentrations. Dynamic changes in fibrin production were depicted. We simulated the correlation between MPs-ACT and standard plasma containing MPs prepared in vitro. The reproducibility of high-value and low-value samples was 6.0% and 10.8%, respectively. MPs-ACT sensitively detected hypercoagulable samples from patients with pre-eclampsia, hip fractures, and lung tumors. MPs-ACT largely reflects the procoagulant effect of MPs. MPs-ACT sensitively and rapidly detects hypercoagulability with MPs-rich plasma. It may be promising for the diagnosis of hypercoagulable states induced by MPs.

Correlations between the Circulating Level of Cell-Derived Microparticles and Surgical Variables in Heart Valve Surgery with Cardiopulmonary Bypass.

Cell-derived microparticles (MPs) as membrane vesicles are procoagulant. They play a role in surgical hemostasis. In this study, the correlations between the circulating level of cell-derived MPs and surgical variables in heart valve surgery were investigated. The present prospective case-series study was conducted in Rajaie Cardiovascular Medical and Research Center from January through March 2021. Forty patients undergoing heart valve surgery with cardiopulmonary bypass (CPB) were enrolled. Before the induction of anesthesia and 30 minutes after the administration of protamine sulfate, venous blood samples were collected. After MP isolation, the concentration of MPs was determined via the Bradford method. Flow cytometry analysis was performed to determine the MP count and phenotype. Intraoperative variables and postoperative routine coagulation tests were defined as surgical variables. Postoperative coagulopathy was defined as an activated partial thromboplastin time (aPTT) ≥48 seconds or an international normalized ratio (INR) >1.5. The total concentration of MPs and the MP count increased significantly after surgery compared with before surgery. The postoperative concentration of MPs was positively correlated with the CPB time (P=0.030, ρ=0.40). The preoperative concentration of MPs was significantly lower in patients with higher postoperative aPTT and INR (P=0.003, P= -0.50 and P=0.020, P= -0.40, respectively). In multivariate logistic regression analysis, the preoperative MP concentration (OR, 1.00; 95% CI, 1.00 to 1.01; P=0.017) was considered a risk factor for postoperative coagulopathy. The levels of MPs, especially platelet-derived MPs, rose after surgery, in correlation with the CPB time. Given the role of MPs in the induction of coagulation and inflammation, they can be considered therapeutic goals for preventing postoperative complications. In addition, the preoperative levels of MPs are a risk factor for predicting the occurrence of postoperative coagulopathy in heart valve surgery.

The Characteristics of PM2.5 and PM10 and Elemental Carbon Air Pollution in Sevastopol, Crimean Peninsula

In most cities of the world, air pollution reaches critical levels. The air masses circulating over the Crimean Peninsula bring a significant amount of mineral dust, which contains soil particles, emissions from industrial enterprises, gases, etc. The purpose of this research is to study the processes and the factors influencing atmospheric pollution in Sevastopol (Crimea). Air pollutant concentration data, including elemental carbon, nutrients (inorganic fixed nitrogen, inorganic fixed phosphorus and silicon), PM10, and PM2.5, were collected during this research. Samples were collected at the station that is located at a distance from sources of pollution (background station). Our study has shown that even at the background site the daily-averaged concentrations of PM10 and PM2.5 particles in the atmosphere of Sevastopol reach and even exceed the maximum permissible concentrations in the case of dust transported from deserts. Values of the daily-averaged concentrations of microparticles have exceeded the European maximum permissible concentration (MPC) values in 17 cases for PM2.5 particles and in 6 cases for PM10. The impact of both local sources and long-distance atmospheric transport depends on weather conditions. Concentrations of elemental carbon in air samples have never exceeded the maximum allowed by regulations concentration limits during our research. However, the elemental carbon concentration in air samples collected near highways with a traffic intensity of approximately 500–1000 cars per hour has exceeded the background values by 30–50 times.

Size-Controllable Synthesis of Monodisperse Magnetite Microparticles Leading to Magnetically Tunable Colloidal Crystals

Colloidal crystals (CCs) are periodic arrays of monodisperse microparticles. Such CCs are very attractive as they can be potentially applicable as versatile photonic devices such as reflective displays, sensors, lasers, and so forth. In this article, we describe a promising methodology for synthesizing monodisperse magnetite microparticles whose diameters are controllable in the range of 100–200 nm only by adjusting the base concentration of the reaction solution. Moreover, monodisperse magnetite microparticles in aqueous suspensions spontaneously form the CC structures under an external magnetic field, leading to the appearance of Bragg reflection colors. The reflection peak can be blue-shifted from 730 nm to 570 nm by the increase in the external magnetic field from 28 mT to 220 mT. Moreover, the reflection properties of CCs in suspension depend on the microparticle concentration in suspension and the diameter of the magnetite microparticles. Both fine-control of microparticle diameter and investigation of magneto-optical properties of CCs would contribute to the technological developments in full-color reflective displays and sensors by utilizing these monodisperse magnetite microparticles.

Effect of concentration of silica encapsulated ds-DNA colloidal microparticles on their transport through saturated porous media

We investigated the transport and retention kinetics of silica encapsulated – silica core double stranded DNA particles (SiDNASi) through 15 cm saturated quartz sand columns as a function of a wide range of colloid injection concentrations (C0 = 8.7 ×102 - 6.6 ×108 particles ml−1). The breakthrough curves (BTCs) exhibited an overall 2-log increase of maximum relative effluent concentration with increasing C0. Inverse curve fitting, using HYDRUS1D, demonstrated that a 1-site first order kinetic attachment (katt) and detachment (kdet) model sufficed to explain the C0-dependent SiDNASi retention behaviour. With increasing C0, katt log-linearly decreased, which could be expressed as an overall decrease in the single-collector removal efficiency (ƞ). The decrease in ƞ was likely due to increased electrostatic repulsion between aqueous phase- solid phase colloids, formation of shadow zones downstream of deposited colloids and removal of weakly attached colloids from the solid phase (quartz sand) attributing to increased aqueous phase-solid phase intercolloidal collisions as a function of increasing SiDNASi concentration. Our results implied, firstly, that the aqueous phase colloid concentration should be carefully considered in determining colloidal retention behaviour in saturated porous media. Secondly, colloidal transport and retention dynamics in column studies should not be compared without considering colloid influent concentration. Thirdly, our results implied that the applicability of SiDNASi as a conservative subsurface tracer was restricted, since transport distance and retention was colloid concentration dependent. However, the uniqueness of the DNA sequences in SiDNASi imparts the advantage of concurrent use of multiple SiDNASi for flow tracking or porous media characterization.

Correlation of laboratory markers of hemostatic system activation with concentration and size of plasma extracellular microparticles in patients with COVID-19

Introduction. In recent years, much attention has been paid to the study of extracellular microparticles (microvesicles and exosomes) and their role in the pathogenesis of human diseases.The objective of this study was to determine the number and size of plasma extracellular microparticles (PEMP) in patients with severe and extremely severe COVID-19 and correlate these data with the markers of hemostasis activation, inflammation, and tissue damage.Methods and Materials. The study included 29 patients with severe and extremely severe COVID-19. Concentration and size of PEMP were determined by nanoparticle trajectory analysis (NTA). All patients underwent the complete blood count and the thromboelastometry (TEM). Hemostatic, biochemical, and immunological parameters were assessed including fibrinogen, prothrombin time, activated partial thromboplastin time, D-dimer, C-reactive protein, lactate dehydrogenase, procalcitonin, von Willebrand factor antigen, interleukin 6, and interleukin 18.Results. There were 14 patients (48.3 %) discharged from the ICU with improvement (group 1— survived patients), and 15 patients (51.7 %) with lethal outcomes (group 2 — lethal outcome); the PEMP concentration did not differ between these groups. In group 2, there were heterogeneity of PEMP population, and a tendency to the larger PEMP size (p=0.074). In all patients, the PEMP concentration correlated negatively with both prothrombin time and the number of large platelets; the size of PEMP correlated negatively with the level of von Willebrand factor antigen, and positively with the fibrinogen. In group 1, the PEMP concentration had a direct correlation with both the level of interleukin 18 and maximum clot lysis in TEM; the PEMP size had a direct correlation with the maximum clot lysis in TEM and an inverse correlation with both the level of procalcitonin and maximum clot density in TEM.Conclusion. Our study confirms the importance of the process of extracellular microparticles formation in the COVID-19 pathogenesis. Our findings are consistent with the hypothesis that the parameters of PEMP population can be predictive biomarkers of the COVID-19 severity.

Plasma extracellular vesicle miRNAs as potential biomarkers of the transition from compensated cardiac hypertrophy to heart failure in rats

Hypertension and cardiac hypertrophy initiate molecular pathways that can result in heart failure (HF). Despite the importance of cardiac hypertrophy as a risk factor for the development of HF, not all hypertrophied hearts will develop HF. Possibly, HF‐prone hearts are molecularly defined in the early stages of the disease, before the transition to HF. HF diagnosis is most often made at an advanced stage of the disease. This determines the need of markers at the earliest possible stage of the disease. Circulating microRNAs have been considered novel candidate biomarkers for HF. The aim of the present study was to identify if plasma extracellular vesicles (EVs) microRNAs could be used as biomarkers during the transition of compensated cardiac hypertrophy to HF in rats submitted to abdominal aorta constriction. Previous published data from our group showed that at 60‐days post‐surgery (dps) there was 2 groups: controls and operated animals with compensated cardiac hypertrophy and preserved systolic function. At 90 dps, the operated group was subdivided into 2 groups: animals with hypertrophic hearts (resistance to heart failure, R‐HF), around 70% of the animals, and animals with hypertrophic + dilated hearts (HF), around 30%. Since at 60 dps there was no difference among operated animals by echocardiography and there is no signal which animal will develop HF, a retrospective study was performed: plasma microRNAs from animals at 90 dps (HF‐90dps and R‐HF‐90dps) were compared to the plasma from the same animals earlier at 60 dps (HF‐60dps and R‐HF‐60dps) to identify possible microRNAs that could be used as early biomarker of HF. Plasma was collected before surgery and at 60 and 90 dps. Ejection fraction (EF) was evaluated by echocardiography. Plasma circulating microparticles concentration and size were characterized by Nanoparticle tracking analysis. Relative levels of 312 rat miRNAs were evaluated by RT‐qPCR at 60 dps. Data were considered significant when p&lt;0.05. There is no difference in the EF among sham (61.85±6.62%), R‐HF‐60dps (59.50±8.05%) and 60dps (62.07±8.91%) and R‐HF‐90dps (56.33±7.76%). There is no difference in the particle concentration among sham (3.24x1011/ml), R‐HF‐60dps (5.48x1011/ml) and HF‐60dps (3.54x1011/ml). The same was seen in relation to particles size: sham (104.98 nm), R‐HF‐60dps (104.88 nm) and HF‐60dps (107.25 nm). The microRNA profiling detected a total of 191 miRNAs present in sham, R‐HF‐60dps and HF‐60dps. Of these, a total of 42 miRNA were upregulated in the group HF‐60dps when compared to R‐HF‐60dps (let‐7b‐5p; let‐7d‐3p; 125a‐5p; 127‐3p; 130a‐3p; 149‐5p; 30d‐5p; 30e‐5p; 31b; 34a‐3p; 423‐5p; 499‐5p; 145‐5p; 146a‐3p; 15a‐3p; 181d‐5p; 182, 185‐5p; 193b‐5p; 211‐5p; 322‐3p; 375‐5p; 351‐5p; 500‐3p; 92b‐3p; 212‐3p; 22‐3p; 21‐5p; 221‐3p; 27b‐3p; 21‐5p; 221‐3p; 27b‐3p; 301a‐3p; 28‐3p; 301b‐3p; 30a‐5p; 486; 423‐3p; 497‐5p; 671 and 99a‐5p). Further studies at 90 dps should be performed. These 41 upregulated miRNAs need to be compared to the miRNA profiling at 90 dps. If any of these miRNAs are still upregulated at 90 dps, the predicted pathways regulated by these miRNAs can be analyzed and these miRNAs could be used as a biomarker of HF in these animals.

Effect of Incorporation of Bioactive Glass-Ceramic into Self-etch Adhesives.

This study evaluated the effect of incorporating different concentrations of biosilicate in an experimental self-etch adhesive (SE). Biosilicate microparticles (0, 2, 5, and 10 wt%) were incorporated into the primer, and degree of conversion (DC) and wettability were tested (one-way ANOVA, Tukey's test, p < 0.05). The two best concentrations were selected (2% and 5%) for µTBS evaluation. Sound human molars (n=20) were sectioned into quarters and randomly assigned to 4 experimental groups: 1. experimental SE + 0% biosilicate (Exp0%; negative control); 2. experimental SE + 2% biosilicate (Exp2%); 3. experimental SE + 5% biosilicate (Exp5%); 4. AdheSE (Ivoclar Vivadent, positive control). After adhesive application, Filtek Z350 (3M Oral Care) composite was built up incrementally to 5 mm. Each quarter tooth was sectioned into sticks (0.9 mm2) and stored in distilled water (37°C) for 24 h, 6 months, or 1 year. After storage, sticks were submitted to µTBS (0.75 mm/min). The Ca:P ratio was analyzed using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). Data were analyzed using two-way ANOVA with Bonferroni's correction, with statistical siginificance set at p < 0.05. Fracture patterns were observed under a digital microscope and adhesive interfaces with transmission electron microscopy (TEM). Exp2% presented the highest DC (p < 0.05), Exp5% exhibited the lowest µTBS (p < 0.05), and adhesive failures were predominant in all groups. TEM suggested remineralized areas in Exp2% and to a lesser degree in Exp5%. Exp2% and Exp5% showed a higher Ca:P ratio after aging (p < 0.05). The incorporation of biosilicate microparticles can improve the properties of self-etch adhesives. It increased the DC of the experimental adhesive as well as mineral deposition. However, the adhesive properties are concentration dependent, as a higher concentration of microparticles can adversely affect the mechanical properties of an adhesive.

Removal of microparticles and bacterial inactivation in freshwater RAS by use of foam fractionation, H 2 O 2 and NaCl

Foam fractionation (FF) is an effective water treatment technology used to remove fine particles in seawater recirculating aquaculture systems (RAS). However, there is only limited available information on the operation and efficiency of FF in freshwater. This study investigated the treatment efficiency of FF by measuring changes in bacterial activity and microparticle densities in freshwater from RAS. Thirty-six separate batch tests were performed with FF separately and in combination with addition of hydrogen peroxide (H2O2) and salt (NaCl). Both chemicals are commonly used for water treatment in freshwater aquaculture. The experiment was a 2 × 2 × 3 factorial design with 3 factors: FF (present or absent), H2O2 (0 or 10 mg L⎻1) and NaCl (0, 3, or 10 ppt). FF reduced the concentration of microparticles and turbidity in freshwater by 58.7 ± 5.4% and 27.5 ± 3.8% respectively. H2O2 had a significant antimicrobial effect, and the combination of H2O2 and FF resulted in an 80% reduction in bacterial activity in freshwater. Addition of NaCl improved the efficiency of FF by further reducing particle concentration and turbidity two-fold at 10 ppt compared to 0 ppt. This study provides new knowledge on the potential use of FF to improve the water quality in freshwater RAS, and this was further enhanced by the addition of H2O2 or NaCl.

Concentration of Microparticles Using Flexural Acoustic Wave in Sessile Droplets.

Acoustic manipulation of microparticles and cells has attracted growing interest in biomedical applications. In particular, the use of acoustic waves to concentrate particles plays an important role in enhancing the detection process by biosensors. Here, we demonstrated microparticle concentration within sessile droplets placed on the hydrophobic surface using the flexural wave. The design benefits from streaming flow induced by the Lamb wave propagated in the glass waveguide to manipulate particles in the droplets. Microparticles will be concentrated at the central area of the droplet adhesion plane based on the balance among the streaming drag force, gravity, and buoyancy at the operating frequency. We experimentally demonstrated the concentration of particles of various sizes and tumor cells. Using numerical simulation, we predicted the acoustic pressure and streaming flow pattern within the droplet and characterized the underlying physical mechanisms for particle motion. The design is more suitable for micron-sized particle preparation, and it can be valuable for various biological, chemical, and medical applications.

Laser fragmentation of silicon microparticles in liquids for solution of biophotonics problems

The possibility of manufacturing silicon nanoparticles by picosecond laser fragmentation of silicon microparticles in water is analysed. It is shown that for fragmentation duration of 40 min, the dependence of the average sizes of particles on the initial mass concentration of the micropowder varied in the range of 0.5 – 12 mg mL−1 is nonmonotonic, with the maximum average size of 165 nm being achieved at a concentration of 5 mg mL−1. To explain the obtained result, the simulation of propagation of a focused laser beam in a scattering suspension of silicon microparticles is performed for their different mass concentrations. It is demonstrated that at concentrations not exceeding 5 mg mL−1, fragmentation occurs in the paraxial region of the beam when it propagates deep into the cuvette with a suspension, while at higher concentrations it occurs primarily in the superficial layer owing to strong extinction. Calculations results allow the experimental features of the formation of silicon nanoparticles to be explained. Spectrophotometry measurements on suspensions of nanoparticles obtained at the initial concentration of microparticles of 12 mg mL−1 are compared with the theoretical estimates of the absorption and scattering coefficients obtained in the framework of the Mie theory. Measured optical properties indicate the potential of using fragmented nanoparticles as scattering and/or absorbing contrast agents in optical imaging of biological objects.

Магнитный импеданс пленочных наноструктур для оценки полей рассеяния микрочастиц магнитных композитов

Longitudinal giant magnetoimpedance effect of [Fe21Ni79/Cu]5/Cu/[Fe21Ni79/Cu]5 film element was investigated depends on stray magnetic field of epoxy magnetic composite with 30 % weight concentration of iron oxide magnetic microparticles. Configuration of an experiment was a model of thrombus detection in a blood vessel. Stray magnetic field was varied by movement of a magnetic composite above the element perpendicular to the long side. Composite was either magnetized or not to the state of remanence. As the magnetic composite approaches the GMI element, MI ratio curves are smoothed and shifted along the field axis and maximum value of the MI ratio decreases. Magnetic properties of magnetic composite and film element were investigated as well.

Effects of TaC microparticles on structure and properties of micro-arc oxidation coating on Ti-6Al-4V alloy

In order to improve the corrosion resistance and wear properties of the micro arc oxidatin (MAO) coatings on Ti-6Al-4V alloy in the marine environment, TaC-doped MAO coatings are prepared by adding different concentrations of TaC microparticles with a particle size of about 1 μm into the silicate-based electrolyte. The morphology, elemental distribution and composition of the coatings are characterized and analyzed by SEM, EDS and XPS. The thickness, roughness, hardness, wear resistance and corrosion resistance for each of the three MAO coatings are evaluated and their corresponding values of these coatings are compared with each other. The results show that by adding TaC microparticles into the base electrolyte, TaC and Ta&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; are present in the MAO coatings on titanium alloy. Compared with the MAO coating without TaC, the surface morphology of the coating with TaC is dense and the hardness is increased by about 83.2%. The friction coefficient of the coating in the simulated seawater decreases from 0.2 to 0.148, changing from serious abrasive wear to slight adhesive wear. The corrosion current density of this coating decreases by two orders of magnitude. Furthermore, by constructing the wear and corrosion failure model of the MAO coatings in the simulated seawater, the internal mechanism of doping TaC microparticles into the MAO coating to improve its corrosion resistance and wear resistance is revealed.

Magnetic impedance of film nanostructures for stray magnetic field evaluation of microparticles in magnetic composites

Longitudinal giant magnetoimpedance effect of [Fe21Ni79/Cu]5/Cu/[Fe21Ni79/Cu]5 film element was investigated depends on stray magnetic field of epoxy magnetic composite with 30% weight concentration of iron oxide magnetic microparticles. Configuration of an experiment was a model of thrombus detection in a blood vessel. Stray magnetic field was varied by movement of a magnetic composite above the element perpendicular to the long side. Composite was either magnetized or not to the state of remanence. As the magnetic composite approaches the GMI element, MI ratio curves are smoothed and shifted along the field axis and maximum value of the MI ratio decreases. Magnetic properties of magnetic composite and film element were investigated as well. Keywords: Magnetoimpedance effect, multilayered film nanostructures, composite materials, biodetection.

Static puncture resistance characteristics with various indenter nose shape geometry perforation of shear thickening fluid impregnated polypropylene fabric for soft armour application

At present, puncture resistance and rheological performance of shear thickening fluid (STF) is an essential design requirement for a soft armour material (target sample). The target sample is prepared with a dip and dry process of STF impregnated woven polypropylene (PP) fabric. These samples were tested and compared with neat PP fabric. The penetration depth of target samples is highly sensitive to the coefficient of friction between the indenter’s nose shape geometry and the target sample. The STF is prepared by mechanical dispersion of synthesized microsphere silica microparticles at a volume fraction of 57% in polyethylene glycol (400 g/mol). The rheological response indicates that the prepared concentration of silica microparticles in the STF suspension is observed to have a better shear thickening effect. The viscosity of suspension is highly sensitive to silica aspect ratio, volume fraction and particle size distribution in this work. Tensile tests along with puncture resistance with different indenter nose shapes geometry (hemispherical, elliptical, flat and conical) have been performed in the present study. Results indicate that the energy absorption is more with the hemispherical indenter and less with that of the conical indenter, which is attributed to the minimum surface area of contact as compared to all other indenters. A total of 16 number of fabricated target samples with various coating thicknesses of STF impregnated fabrics achieved the desired tensile strength, modulus and puncture resistance.