Search Results (12)

Background: Gadolinium-based contrast agents (GBCA) are widely used in magnetic resonance imaging (MRI) to enhance image contrast by interacting with water molecules, thus improving diagnostic capabilities. However, understanding the residual accumulation of GBCA in tissues after administration remains an area of active research. This highlights the need for advanced analytical techniques capable of investigating interactions between GBCAs and biopolymers, such as type I collagen, which are abundant in the body. Objective: This study explores the interactions of neutral and charged GBCAs with type I collagen under physiological pH conditions (pH 7.4) using Taylor dispersion analysis (TDA) and frontal analysis continuous capillary electrophoresis (FACCE). Methods: Collagen from bovine achilles tendon was ground using a vibratory ball mill to achieve a more uniform particle size and increased surface area. Laser granulometry was employed to characterize the size distributions of both raw and ground collagen suspensions in water. TDA was used to assess the hydrodynamic radius (R_h) of the soluble collagen fraction present in the supernatant. Results: From the TDA and FACCE results, it was shown that there were no significant interactions between the tested GBCAs and either the ground collagen or its soluble fraction at pH 7.4. Interestingly, we also observed that collagen interacts with filtration membranes, indicating that careful selection of membrane material, or the absence of filtration in the experimental protocol, is essential in interaction studies involving collagen. Conclusion: These findings bring valuable insights into the behavior of GBCAs in biological systems with potential implications for clinical applications. Full article

The symptoms of multiple sclerosis (MS) are determined by the location of demyelinating lesions in the white matter of the brain and spinal cord. Currently, magnetic resonance imaging (MRI) is the most common tool used for diagnosing MS, understanding the course of the disease, and analyzing the effects of treatments. However, undesirable components may appear during the generation of MRI scans, such as noise or intensity variations. Mathematical morphology (MM) is a powerful image analysis technique that helps to filter the image and extract relevant structures. Granulometry is an image measurement tool for measuring MM that determines the size distribution of objects in an image without explicitly segmenting each object. While several methods have been proposed for the automatic segmentation of MS lesions in MRI scans, in some cases, only simple data preprocessing, such as image resizing to standardize the input dimensions, has been performed before the algorithm training. Therefore, this paper proposes an MRI preprocessing algorithm capable of performing elementary morphological transformations in brain images of MS patients and healthy individuals in order to delete undesirable components and extract the relevant structures such as MS lesions. Also, the algorithm computes the granulometry in MRI scans to describe the size qualities of lesions. Using this algorithm, we trained two artificial neural networks (ANNs) to predict MS diagnoses. By computing the differences in granulometry measurements between an image with MS lesions and a reference image (without lesions), we determined the size characterization of the lesions. Then, the ANNs were evaluated with the validation set, and the performance results (test accuracy = 0.9753; cross-entropy loss = 0.0247) show that the proposed algorithm can support specialists in making decisions to diagnose MS and estimating the disease progress based on granulometry values. Full article

Every year, metallurgical enterprises generate a massive amount of toxic exhausted high-concentration etching solutions. Application of the ferritization process to recycle exhausted etching solutions can help to prevent environmental pollution. It enables a cost-efficient use of water at an industrial plant and allows the plant to obtain products from toxic industrial waste and utilize it. The aim of the study was to analyze the qualitative and quantitative composition of the formed sediment and its grain size composition. Variable study parameters were the initial pH values of the solutions, the initial concentrations of total iron, and the duration of the aeration process of the reaction mixture. Thermal activation and alternating magnetic fields were used to activate the ferritization. The XRD showed that the formed sediments contained phases of γ-FeOOH, δ-FeOOH, Fe₃O₄, and γ-Fe₂O₃. Granulometry analysis showed that these sediments were highly dispersed and heterogeneous. Chemically stable phases of magnetite were obtained in the composition of sediments, with an initial concentration of iron in the reaction mixture of 16.6 g/dm³, a pH of 11.5, and a process duration of 15 min. The study results demonstrated the feasibility of further study and possible use of such sediments with a high magnetite content for the production of materials with ferromagnetic and sorption properties. Full article

Artificial glasses containing nanoscale inclusions of iron oxides, including magnetite and hematite, were obtained via the method of the high-temperature melting of rocks. The main factors influencing the magnetic properties of glasses are the composition of the initial charge and the conditions of cooling of the melt. The data of magnetic granulometry and frequency-field dependencies of magnetic susceptibility showed the presence of a sufficiently large superparamagnetic fraction in the samples. Coordinated theoretical modeling using two independent models that take into consideration possible the chemical inhomogeneity of particles and magnetostatic interaction between them made it possible to calculate hysteresis characteristics corresponding to the experiment and to estimate ferrimagnetic concentrations in the samples, including the superparamagnetic fraction. Full article

The exponential growth in the consumption of electronics, in combination with the reduction in their useful life, has led to a significant increase in the volume of electronic materials which are discarded. Printed Circuit Boards (PCBs) are modules composed of ceramic, polymer, and metallic materials of high economic value and with a great potential for damage to biotic and anthropic environments when inadequately discarded. The aims of this work were to study the main environmental impacts and the efficiency of mechanical operations in the electronic waste recycling process in optimizing the concentration of metallic copper. For this, the samples obtained were characterized according to their morphology and chemical composition, and subjected to physical and mechanical treatments: dismantling, grinding, separation by granulometry, density, and magnetic property. The environment impacts were estimated by the Life Cycle Assessment of the pre-treatment processes, associated with copper extraction operations in Waste Printed Circuit Boards (WPCBs). According to the results obtained, it is possible to infer that the NM + 1 mm Concentrated product presents in its metallic composition around 78% copper, which contributes to the efficiency of the hydrometallurgical extraction processes. It is noteworthy that the Concentrated class represents about 14% of copper (wt) taking into account the amount of 3.789 kg of PCB waste input material. The potential for reinsertion of the dust in the material recovery process is highlighted, given that the chemical composition of this particulate has a significant presence of metals. In general, it was found that due to the higher concentration (wt%) of the sample being allocated in the range of −0.15 mm + 0.05 mm, the elements Fe (18.30%), Si (10.73%), Ca (9.21%), and Cu (8.89%) stand out regarding the participation of the elemental composition of this fraction and also regarding the general composition of the sample. Furthermore, the generation of dust during the fragmentation process can be associated with occupational respiratory diseases when not managed. About the Life Cycle Assessment, in seven of the nine categories evaluated, crushing and screening activities accounted for more than 90% of the recorded impact values. In general, it is estimated that in the pre-treatment phase it generated 15.4 kg CO₂ eq. Full article

In order to understand further the emplacement (i.e., volcanic growth) of 22 Icelandite and 3 Rhyodacite cooling units in one of the long volcanic sequences known as Mauna Kuwale of the Wai’anae volcano (ca. 3.3 Ma), Oahu Hawaii we have conducted appropriate rock magnetic experiments described below as well as anisotropy of magnetic susceptibility (AMS) studies of such 25 units. We have undertaken rock magnetic investigations such as continuous and partial thermo-magnetic cycles of low field magnetic susceptibility versus temperature dependence, (k-T) curves experiments. We classified the k-T heating-cooling dependence of susceptibility in three groups A, B and C. Type A: yielded two components of titano-magnetite with a predominat Ti rich phase and occasionally a relevant magnetite component phase. Type B: samples are characterized by Ti poor magnetites. Magnetite dominates as the main magnetic carrier. Type C: k-T curves show one single phase of titanomagnetite, and Ti poor magnetite. The coercivity or remanence, determined by back field magnetization is always <60 mT, which suggest the predominance of magnetic components of low coercivity, like magnetite. Usually, two coercivity components are identified in the specimens. In addition we also conducted magnetic granulometry analyses on 27 specimens to determine the domain state of the flows. The ratio of hysteresis parameters (Mr/Mrs versus Hcr/Hc) show that overall samples fall in the Pseudo-Single Domain (PSD) region with high values of Mr/Mrs and very low values of Hcr/Hc. Only two samples from cooling units 17 and specially 22 show a Single Domain (SD) magnetic behavior and a sample from one unit approaches the SD-MD mixture region. We measured the magnetic susceptibility of all cooling units and we found out that in all analyzed units the magnetic susceptibility is low 13.7 ± 8.8 (10⁻³ SI). Magnetic anisotropy/magnetic fabric is used as a tool in rock fabric analyses to investigate the preferred orientation of magnetic minerals in rocks. Magnetic anisotropy is low on all (measured) flows from the Icelandite cooling units from 1 to 17 (mean P’ = 1.010), but becomes noticeably distinct and high in rhyodacite cooling units 23, 24 and 25 (mean P’ = 1.074). Four units show a magnetic fabric with k₃ axes vertical to sub-vertical which may be denoted as normal for the horizontal to sub horizontal units. Two Icelandite cooling units display oblate shapes and two other cooling units triaxial shapes. K₁ axes are horizontal but point in different directions, i.e., NE and NW. Remaining cooling units show different magnetic fabric. Units 17, 23, 24 and 25, despite important variations in anisotropy (low for units 25 and high for units 23 and 24) and shape of ellipsoid (oblate in cooling unit 23, prolate in 24 and triaxial in 25) the k₃ axes show the same orientation, SW to SSW dipping around 45° and a very steady magnetic lineation azimuth NW nearly horizontal to sub horizontal. The magnetic mineralogy and magnetic fabric indicate that both the Icelandite and Rhyodacite cooling units the magmatic evolution during the shield stage of the entire Wai’anae volcano and that such growth was not affected by tectonic deformation. Full article

This paper aims to reconstruct the alluvial activity for the Lilas river, the second-largest catchment of Euboea Island (Central Western Aegean Sea), for approximately the last three and a half millennia. The middle reaches (Gides basin) exhibit several historical alluvial terraces that were first recognised in the 1980s but have remained poorly studied, resulting in uncertain chronological control of palaeofluvial activity. In order to reconstruct the past fluvial dynamics of the Lilas river, a ca. 2.5 m thick stratigraphic profile has been investigated for granulometry and magnetic parameters. Absolute dating of the sediments was possible by applying Optically Stimulated Luminescence (OSL). The results reveal: (i) two coarse-grained aggradational episodes dated from the Mycenaean/Early Iron Age and the Roman periods, respectively, (ii) a phase of rapid fine-grained vertical accretion corresponding to the Late Byzantine to early Venetian periods, (iii) potential evidence for final alluvial deposition from the Little Ice Age/Ottoman period, and (iv) two major incision episodes inferred from Ancient Greek times and most of the Byzantine period. Based on the published core material, the paper also evaluates the direct impacts of the Late Holocene alluviation recorded mid-stream on the fluvial system situated downstream in the deltaic area. Sediment sourcing is attempted based on the magnetic properties of the catchment lithology and of alluvium collected upstream along the main stream bed. Finally, the present paper discusses the possible links between Late Holocene hydroclimatic oscillations and the aggradational/incision phases revealed in the Gides basin. Correlations are attempted with regional palaeoclimate records obtained for the Aegean. In addition to climatic variability, anthropogenic factors are considered: specific land use for agricultural purposes, in particular during the Mycenaean period, the Roman and the Late Byzantine/Early Venetian periods, might have enhanced sediment deposition. Archaeological information and pollen records were also evaluated to reconstruct regional land-use patterns and possible impacts on soil accumulation over the last 3.5 millennia. Full article

The size-dependent properties of magnetic nanoparticles (MNP) are the major characteristics, determining MNP application in modern technologies and bio-medical techniques. Direct measurements of the nanosized particles, involved in intensive Brownian motion, are very complicated; so the correct mathematical methods for the experimental data processing enable to successfully predict the properties of MNP suspensions. In the present paper, we describe the fast numerical algorithm allowing to get the distribution over the relaxation time of MNP magnetic moments in ferrofluids. The algorithm is based on numerical fitting of the experimentally measured frequency spectra of the initial dynamic magnetic susceptibility. The efficiency of the algorithm in the solution of the inverse problem of magnetic granulometry is substantiated by the computer experiments for mono- and bi-fractional ferrofluids. Full article

The physico-chemical characteristics of particulate matter (PM) in African cities remain poorly known due to scarcity of observation networks. Magnetic parameters of PM are robust proxies for the emissions of Fe-bearing particles. This study reports the first magnetic investigation of PM2.5 (PM with aerodynamic size below 2.5 μm) in Africa performed on weekly PM2.5 filters collected in Abidjan (Ivory Coast) and Cotonou (Benin) between 2015 and 2017. The magnetic mineralogy is dominated by magnetite-like low coercivity minerals. Mass normalized SIRM are 1.65 × 10⁻² A m² kg⁻¹ and 2.28 × 10⁻² A m² kg⁻¹ for Abidjan and Cotonou respectively. Hard coercivity material (S-ratio = 0.96 and MDF = 33 mT) is observed during the dry dusty season. Wood burning emits less iron oxides by PM2.5 mass when compared to traffic sources. PM2.5 magnetic granulometry has a narrow range regardless of the site or season. The excellent correlation between the site-averaged element carbon concentrations and SIRM suggests that PM2.5 magnetic parameters are linked to primary particulate emission from combustion sources. Full article

Toxic organic solvent residues and the active substances of thermal degradation (such as anthocyanin and polyphenols) are always a concern with the liposomes produced by traditional techniques. The present study focuses on a new approach for the microencapsulation of Clitoria ternatea petal (CTP) extracts, which contain anthocyanins, by high-pressure processing (HPP) at room temperature. Thus, a series of CTP liposomes were prepared and their physicochemical properties were analyzed by laser granulometry and by scanning electron microscopy (SEM). The results revealed that the average particle size of the liposomes after HPP treatment increased gradually from 300 MPa to 600 MPa, possibly due to the aggregation of liposomes and damage to the phospholipid bilayers. For the preparation of liposomes by the HPP method at 300 MPa, the mean particle size, polydispersity index (PDI), and encapsulation efficiency were 240.7 nm, 0.37, and 77.8%, respectively. The HPP method provided a number of advantages over conventional methods (magnet stirring and ultrasonication) as it could allow liposome preparation with higher encapsulation efficiency, smaller size, and narrower, more reproducible particle size distribution. Conclusively, microencapsulation in the liposomes was successfully achieved with the fast-adiabatic expansion of HPP. Full article

The main objective of the presented preliminary study was the identification of iron-containing phases. Iron-containing phases had accumulated in organic topsoil horizons collected from an area that has long been affected by the steel industry and emissions from power plants. X-ray diffraction and Mössbauer spectroscopy methods were used for the determination of the iron-containing mineral phases in topsoil subsamples which, after two-staged separation, varied in terms of magnetic susceptibility and granulometry. The Mössbauer spectra were recorded using paramagnetic and magnetic components, although the latter occurred only in the strongly magnetic fraction. The central part of spectra was fitted by two doublets (D1 and D2), which were identified as aluminosilicates. Simultaneously, the experimental spectra were described using several Zeeman sextets (Z1, Z2, and Z3) corresponding to the occurrence of hematite and magnetite-like phases with iron in tetrahedral and octahedral sites. Identification of magnetic phases in the tested material, including hematite, led to the conclusion that soil contamination in the studied area was presumably caused by emissions from a nearby power plant. Magnetite-like phases with a different iron content detected in topsoil samples could be related to metallurgical and coking processes, reflecting the specificity of the industrial area from which the samples were taken. The specific composition of the iron-containing aluminosilicates also illustrated the intense and long-lasting impact of the steel and coking industries on the studied area. Full article

In this study, magnetic maghemite nanoparticles, which belong to the group of metal oxides, were functionalized with chitosan, a non-toxic, hydrophilic, biocompatible, biodegradable biopolymer with anti-bacterial effects. This was done using different synthesis methods, and a comparison of the properties of the synthesized chitosan functionalized maghemite nanoparticles was conducted. Characterization was performed using scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). Characterizations of size distribution were performed using dynamic light scattering (DLS) measurements and laser granulometry. A chitosan functionalization layer was confirmed using potentiometric titration on variously synthesized chitosan functionalized maghemite nanoparticles, which is important for further immobilization of bioactive compounds. Furthermore, after activation of chitosan functionalized maghemite nanoparticles with glutaraldehyde (GA) or pentaethylenehexamine (PEHA), immobilization studies of enzyme cholesterol oxidase (ChOx) and horseradish peroxidase (HRP) were conducted. Factors influencing the immobilization of enzymes, such as type and concentration of activating reagent, mass ratio between carrier and enzyme, immobilization time and enzyme concentration, were investigated. Briefly, microparticles made using the chitosan suspension cross-linking process (MC2) proved to be the most suitable for obtaining the highest activity of immobilized enzyme, and nanoparticles functionalized with chitosan using the covalent binding method (MC3) could compete with MC2 for their applications. Full article