High Magnetite Research Articles

Influence of Technological Factors on the Formation and Transformation of Iron-Containing Phases in the Process of Ferritization of Exhausted Etching Solutions

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.

Effects of Cr2O3 on Metallurgical Properties of High Chromium Vanadium-Titanium Magnetite Flux Pellets

Effects of Cr2O3 on Metallurgical Properties of High Chromium Vanadium-Titanium Magnetite Flux Pellets

Rapid ultrasound driven self-assembled nanoarchitectonics iron oxide-reduced graphene oxide as an anode for Li-ion battery and its electrochemical performance studies

With the scope of identifying an effective nanomaterial as an anode for Li-ion battery under economic synthesis factors, here, high crystalline mesoporous magnetite nanoparticles (m-Fe3O4 NPs) with an average diameter of 45 ± 10 nm were successfully synthesized through facile, one-pot sonoelectrochemical method in 15 min, and it was structurally anchored into sonochemically exfoliated reduced graphene oxide nanosheets (m-Fe3O4@rGO). The morphological studies through FESEM and HRTEM analysis confirm that the m-Fe3O4 were well anchored into rGO nanosheets, and it has maximum magnetic saturation value of 39 emu g−1 and high surface area of 254 m2 g−1. The performance analysis results of m-Fe3O4@rGO nanocomposite as an anode material in half-cell configuration with Li-metal had demonstrated that around 11 % enhancement in first discharge capacity (1440.79 mAh g−1 at 0.2 A g−1 current density), ~50 % increased rate capability (356 mAh g−1 at 5.0 A g−1 current density) than bare m-Fe3O4 electrode and had maintained nearly 441 mAh g−1 after 500 cycles at 2.0 A g−1 current density. These results suggest that the sonochemical method could be a better alternate method when compared to other time-consuming processes like solvothermal method where high temperature is required to fabricate effective nanocomposite for high-rate performance in real time applications of Li-ion battery.

Complex refractive index and single scattering albedo of Icelandic dust in the shortwave part of the spectrum

Abstract. Icelandic dust can impact the radiative budget in high-latitude regions directly by affecting light absorption and scattering and indirectly by changing the surface albedo after dust deposition. This tends to produce a positive radiative forcing. However, the limited knowledge of the spectral optical properties of Icelandic dust prevents an accurate assessment of these radiative effects. Here, the spectral single scattering albedo (SSA) and the complex refractive index (m=n-ik) of Icelandic dust from five major emission hotspots were retrieved between 370–950 nm using online measurements of size distribution and spectral absorption (βabs) and scattering (βsca) coefficients of particles suspended in a large-scale atmospheric simulation chamber. The SSA(λ) estimated from the measured βabs and βsca increased from 0.90–0.94 at 370 nm to 0.94–0.96 at 950 nm in Icelandic dust from the different hotspots, which falls within the range of mineral dust from northern Africa and eastern Asia. The spectral complex refractive index was retrieved by minimizing the differences between the measured βabs and βsca and those computed using the Mie theory for spherical and internally homogeneous particles, using the size distribution data as input. The real part of the complex refractive index (n(λ)) was found to be 1.60–1.61 in the different samples and be independent of wavelength. The imaginary part (k(λ)) was almost constant with wavelength and was found to be around 0.004 at 370 nm and 0.002–0.003 at 950 nm. The estimated complex refractive index was close to the initial estimates based on the mineralogical composition, also suggesting that the high magnetite content observed in Icelandic dust may contribute to its high absorption capacity in the shortwave part of the spectrum. The k(λ) values retrieved for Icelandic dust are at the upper end of the reported range for low-latitude dust (e.g., from the Sahel). Furthermore, Icelandic dust tends to be more absorbing towards the near-infrared. In Icelandic dust, k(λ) between 660–950 nm was 2–8 times higher than most of the dust samples sourced in northern Africa and eastern Asia. This suggests that Icelandic dust may have a stronger positive direct radiative forcing on climate that has not been accounted for in climate predictions.

BIF-hosted high-grade magnetite iron ore targeting by hyperspectral wavelength mapping of chlorite: case study of Qidashan Iron Mine, northeast China

There are two kinds of chlorites occurred in Anshan area, among which the hydrothermal Fe-chlorite with longer Fe-OH wavelength is spatially related to the high-grade magnetite ore, meaning that wavelength mapping of chlorites can be used to target the BIF-hosted high grade iron ore. In this article, quadratic polynomial, cubic spline, and quartic polynomial method were used to interpolate the absorption wavelength near 2250 nm of China ZY1-02D satellite hyperspectral image. The result of quadratic polynomial is continuous without data overlapping or intervals, thus most suitable for discrimination of the chlorites. The field truth shows that the spatial distribution of Fe-chlorite, validated by XRD analysis, is not only in accordance with that of high grade magnetite ore bodies, but also consistent with the recently discovered concealed iron bonanza. The study shows that hyperspectral remote sensing techniques can play significant role in the exploration of magnetite iron ore in east Liaoning Province.

New synthesis route for high quality iron oxide-based nanorings: Structural and magnetothermal evaluations

The present study reports on the successful fabrication of high quality monocrystallite magnetite (Fe3O4) nanorings, based on the transformation of monocrystallite hematite (α-Fe3O4) nanorings, using a wet and mild-temperature-mediated chemical route, as an alternative to the traditional solid–solid annealing methods. Additionally, attempts to fabricate ferrite-based nanorings with different stoichiometry through metal-ion (Mn2+, Zn2+, Co2+, and Fe2+) doping and using solid–solid reaction by annealing the hematite nanorings is herein reported. The nanoring morphology is confirmed by electron microscopy micrographs whereas typical magnetic vortex signature is revealed in magnetic hysteresis cycle measurements recorded at room temperature, via collapsing of open loop at low magnetic fields. Rietveld refinement analysis revealed fabrication of single-phase (except one sample revealing two phases) and high-quality crystalline nanomaterials, identified with standard ICDD cards. The as-fabricated samples were tested in regard to their performance for magnetic hyperthermia application, using AC magnetic field amplitude of 100, 150, 200, and 240 Oe while setting frequency at 330 kHz. The recorded temperature versus time curves were successfully explained by the Box-Lucas method.

Extraction of high purity magnetite from bauxite residue

Bauxite residue is a byproduct of the alumina industry and is characterized by high alkalinity and very fine particle size. Currently, there is a low volume utilization of bauxite residue as an additive in the construction industries, and only 3–4 % of the total volume produced annually (160 million tons) is utilized effectively. Bauxite residue is mainly composed of iron oxide along with oxides of aluminum, calcium, sodium, silicon, and titanium. A high fraction of iron in bauxite residue makes it a potential alternative source. However, recovery of high purity iron products with high recovery is technically challenging. The present work is focused on the recovery of iron from bauxite residue in the form of high purity magnetite through a hydrometallurgical approach. Bauxite residue is first neutralized after leaching with mild hydrochloric acid, followed by the leaching of iron with oxalic acid and photochemical reduction of leach liquor to obtain ferrous oxalate precipitate, which is further converted to high purity magnetite. Three different bauxite residue samples with different mineralogical compositions were used, and a comparative study is presented to illustrate the flexibility of the process toward different grades of bauxite residue.

Size and Composition Control of Magnetic Nanoparticles

Magnetite nanoparticles are a type of magnetic nanoparticle (MNP) that are inexpensive to make and can be formed in different shapes and sizes. MNPs can be used in DNA/RNA purification, drug delivery, and other biomedical applications. The commonly employed solvothermal route to make these MNPs gives the most uniform products with the smallest size distribution, but there is a need to identify easily controlled changes to reaction parameters that can reliably tune the size and composition of the MNPs made by this method. In this work we report simple and reliable methods whereby adjusting the total water content and basic salt concentration affords size and composition control, respectively. We employ synchrotron X-ray absorption measurements to prove our method offers monotonic control over MNP composition from maghemite-rich (γ-Fe2O3) to the more magnetic magnetite (Fe3O4). This demonstrates a simple, general method to produce particles with high magnetite concentration and the desired size.

Water Treatment Method for Removal of Select Heavy Metals and Nutrient Ions Through Adsorption by Magnetite

This study explored the removal of contaminants from surrogate solutions using magnetite particles. Commercially available magnetite was used for the removal of copper, lead, nitrate, and phosphate from surrogate solutions. Single-stage experiments with copper, lead, and phosphate surrogate solutions achieved over 98% removal, while nitrate removal experiments only achieved 7.47%, in 24 h at high (20 g/L) magnetite doses and initial concentrations of 100 mg contaminant/L. Two-stage experiments with copper showed over 99.9% cumulative removal after the second stage. Adsorption kinetics experiments for copper, lead, and phosphate demonstrate rapid uptake of contaminants with high doses of magnetite, removing over 90% of contaminants in 4 min or less and follow a pseudo-second-order model. Ultimately, this study aims to establish the minimum magnetite dose and/or minimum number of stages required to remove contaminants below water quality standards for human and/or aquatic life. Water pollution is a serious global issue, and this study poses a potential solution that can be modified for a variety of applications, including environmental contamination and industrial wastewater treatment.

Comprehensive utilization of bauxite residue for simultaneous recovery of base metals and critical elements

The growing stockpiles of bauxite residue and associated environmental hazards require a sophisticated recycling system for complete utilization and value recovery. The current application is limited as a raw material for building and construction applications. Considering the association of multiple elements (Fe, Al, Si, Ca, Ti, V, Sc) within bauxite residue, metal extraction is of prime interest with respect to the economic value of the final product. The following study presents a hydrometallurgy-based process flowsheet for the sustainable recovery of base metals and critical elements within bauxite residue. Major elements present in bauxite residue are recovered as materials for industrial application, including high purity magnetite, alumina, titania, silica, and calcium carbonate. Trace elements are recovered in the liquid stream generated after the recovery of base metals.

The hydrothermal footprint of the Crixás deposit: New vectors for orogenic gold exploration in central Brazil

The main gold deposits of the Archaean-Paleoproterozoic Terrain of Goiás, in central Brazil, occur in the Crixás Greenstone Belt, one of the five volcanosedimentary sequences of this terrain. The Crixás orogenic gold deposit consists of several orebodies structurally controlled by low to moderate angle thrust faults, hosted in different stratigraphic units that exhibit contrasting mineralization styles and hydrothermal alteration assemblages.This study characterizes the hydrothermal footprints of the Palmeiras Structure and Structure IV, which control the orebodies hosted in the hydrothermally-altered mafic metavolcanic rocks and carbonaceous schists, respectively. We assessed the magnitude of fluid-rock interactions by integrating mineralogical, geochemical, and petrophysical data with the reflectance spectroscopy results for drill core samples for both structures.The Palmeiras Structure hydrothermal footprint is characterized by a distal halo composed of Fe-Mg chlorite + biotite ± carbonates (calcite and Fe dolomite), followed by the intermediate halo defined by epidote + carbonates (dolomite, Fe dolomite, and ankerite) ± Fe-Mg chlorite, and proximal halo composed of muscovite + Fe-enriched chlorite ± paragonite, magnetite, tourmaline, Fe dolomite, and ankerite. Additionally, the chemical pattern of the hydrothermal alteration along the Palmeiras Structure has significantly increased concentrations of alkali (K2O, Na2O, Rb, Cs, Li, and Ba), as well as Fe2O3, Al2O3, TiO2, LOI, U, W, Th, and Ta towards the gold mineralization. Also, the high magnetite concentration resulted in high magnetic susceptibility and density, with values above 1432.00×10–3 SI. In Structure IV, the proximal alteration assemblage comprises muscovite + Fe dolomite, Fe-Mg chlorite + arsenopyrite. The lithogeochemical signature is characterized by enrichment in SiO2, CaO, Na2O, K2O, P, Ba, and pathfinder elements As, W, Sb, Te, that increase towards the gold mineralization. A new potential target hosted in the hydrothermalized metabasalt was identified, whose signature is defined by the occurrence of muscovite, chlorite and enrichment in K2O, Ba, Rb, Li Cs and pathfinder elements such as As, W, Sb, Te.This study demonstrates that the integrated application of reflectance spectroscopy, petrophysics and chemical analyses provide a powerful tool for characterizing the hydrothermal footprint and determining the vectors toward gold mineralization in regional-scale mineral exploration.

Magnetic petrology of the Neoarchean granitoids in the Vila Jussara Suite, Carajás Province, Amazonian Craton

The Vila Jussara Suite (VJS) is formed by Neoarchean (~ 2.75 Ga) granites that are located in the Sapucaia Domain of the Carajás Province (CP), Amazonian Craton. Four petrographic varieties were identified in the VJS: biotite-hornblende monzogranite (BHMzG); biotite-hornblende tonalite (BHTnl); biotite monzogranite (BMzG); and hornblende-biotite granodiorite (HBGd). In terms of magnetic signature, BHMzG has two subgroups: the first subgroup has low magnetic susceptibility (MS) values (0.16 × 10-3 to 0.81 × 10-3) and more commonly contains ilmenite with titanite rims; the second subgroup shows moderate to high MS (1.91 × 10-3 to 6.02 × 10-3) and magnetite dominant over ilmenite. BHTnl has moderate MS (0.85 × 10-3 to 1.36 × 10-3) and dominance of pyrite followed by magnetite. BMzG and HBGd have comparatively high MS (3.35 × 10-3 to 19.3 × 10-3 and 2.14 × 10-3 to 25.0 × 10-3, respectively), with magnetite dominant over pyrite. The granite varieties of the VJS were formed under different oxygen fugacity (fO2) conditions, varying from reducing (< fayalite-magnetite-quartz (FMQ)) to oxidizing conditions (nickel-nickel oxide (NNO) to NNO+1). In addition, biotite-hornblende syenogranite occurs subordinately and shows high MS values and extremely high FeOt/(FeOt + MgO) ratios, both in whole-rock and amphibole and biotite. The granites of the VJS are similar to other Neoarchean granites of the Carajás province. The reduced VJS granites are akin to the ferroan granites of Planalto suite, Estrela Complex and Vila União area and the magnesian granites of VJS approach the magnesian granites of Vila União area.

Design optimization and manufacturing of an innovative precise low-intensity magnetic separator based on a multiphysics model

A wet low-intensity magnetic separator (LIMS) is the workhorse for winning magnetite from a slurry. However, the issue with optimizing LIMS is the balance between attracting too much material and obtaining mixed grains of extremely low-grade material (less than 20 vol% magnetite) in the concentrates and attracting too little material and losing the fine liberated magnetite to the tailings. In this study, an innovative precise low-intensity magnetic separator (PLIMS) was designed and optimized based on a multiphysics numerical model. The design parameters of the magnetic assembly and operational parameters were designed and optimized by predicting the separation performance and particle dynamic trajectory of the PLIMS. In particular, the remnant flux density of the magnet assembly was designed to gradually increase from low to high along the flow direction of the slurry, so that the magnetic particles were subjected to precise magnetic force during the separation process. When the magnetic force is greater than the competitive forces, the magnetic particles are captured on the surface of the drum. Then, the captured particles with different liberation degrees and particle sizes are taken out of the separation zone via rotating drum one by one and become concentrated products of multiple grades. The aim of the process is to capture the high liberation magnetite into the main concentrates to obtain high-grade concentrate products, while also capture the low-grade intergrowth particles into the minor concentrates as much as possible to obtain higher recovery. Furthermore, this principle of magnetic separation of PLIMS was explained by simulating the dynamic capture process of the magnetic particles.To verify whether the design concept of gradient magnet assembly (GMA) has advantages, another uniform magnet assembly (UMA) with the same remnant flux density of all permanent magnets was designed. Comparative studies of the magnetic field distribution and magnetic separation performance of GMA and UMA show that PLIMS of the GMA has more significant separation performance. Finally, a laboratory-level PLIMS with a drum diameter of 300 mm (ϕ300-PLIMS) was manufactured based on all the optimization studies above. By comparing the experimental results with simulated results, the accuracy of the PLIMS recovery and grade prediction results were verified.

Methanogens and Their Syntrophic Partners Dominate Zones of Enhanced Magnetic Susceptibility at a Petroleum Contaminated Site

Geophysical investigations documenting enhanced magnetic susceptibility (MS) within the water table fluctuation zone at hydrocarbon contaminated sites suggest that MS can be used as a proxy for investigating microbial mediated iron reduction during intrinsic bioremediation. Here, we investigated the microbial community composition over a 5-year period at a hydrocarbon-contaminated site that exhibited transient elevated MS responses. Our objective was to determine the key microbial populations in zones of elevated MS. We retrieved sediment cores from the petroleum-contaminated site near Bemidji, MN, United States, and performed MS measurements on these cores. We also characterized the microbial community composition by high-throughput 16S rRNA gene amplicon sequencing from samples collected along the complete core length. Our spatial and temporal analysis revealed that the microbial community composition was generally stable throughout the period of investigation. In addition, we observed distinct vertical redox zonations extending from the upper vadose zone into the saturated zone. These distinct redox zonations were concomitant with the dominant microbial metabolic processes as follows: (1) the upper vadose zone was dominated by aerobic microbial populations; (2) the lower vadose zone was dominated by methanotrophic populations, iron reducers and iron oxidizers; (3) the smear zone was dominated by iron reducers; and (4) the free product zone was dominated by syntrophic and methanogenic populations. Although the common notion is that high MS values are caused by high magnetite concentrations that can be biotically formed through the activities of iron-reducing bacteria, here we show that the highest magnetic susceptibilities were measured in the free-phase petroleum zone, where a methanogenic community was predominant. This field study may contribute to the emerging knowledge that methanogens can switch their metabolism from methanogenesis to iron reduction with associated magnetite precipitation in hydrocarbon contaminated sediments. Thus, geophysical methods such as MS may help to identify zones where iron cycling/reduction by methanogens is occurring.

Mineral thermobarometry and its implications for petrological constraints on Mesoarchean granitoids from the Carajás Province, Amazonian Craton (Brazil)

This paper describes the first investigation of the crystallization parameters of the Mesoarchean granitoids from Ourilândia do Norte, which is located in the midwestern part of the Carajás Province. These rocks are divided into three major groups: (i) sanukitoids composed of amphibole-bearing granitoids and associated intermediate to mafic rocks; (ii) potassic granites composed of biotite monzogranites and associated high-Ti granodiorite; and (iii) subordinated TTG-affinity granitoids (amphibole-bearing trondhjemites and biotite-bearing tonalitic xenoliths). These rocks were formed from different sources at different depths, including enriched mantle (sanukitoids), continental crust (monzogranite), mantle-crust mixture (high-Ti granodiorite) and oceanic crust (TTG-affinity granitoids). Potassic granites and porphyritic sanukitoid facies have high magnetite contents, and consequently high magnetic susceptibility (MS), compared to the equigranular sanukitoid facies and trondhjemite. Thermometers based on apatite saturation in whole-rock indicate liquidus temperatures above 800 °C for all granitoids, reaching 959 °C in the high-Ti granodiorite. Amphibole-based and Si-sensitive geothermometers indicate solidus temperatures from 785 to 738 °C for sanukitoids and 892 to 772 °C for trondhjemite, with estimated emplacement pressures varying from 297 to 80 MPa and 580 to 263 MPa, respectively. Because the potassic granites display an amphibole-free assemblage, no geothermobarometric estimate based on amphibole composition was possible. However, potassic granites are associated with coeval sanukitoids (2.88 Ga), which indicates similar pressure conditions and emplacement depths for these rocks. Crystallization constraints from the Ourilândia sanukitoids are comparable to those of the geochemically similar Rio Maria sanukitoids of the Carajás Province, although the pressure estimates and water content show differences. The Fe/(Fe + Mg) ratios of both biotite and amphibole indicate high to intermediate redox conditions for the sanukitoids and potassic granites, which are mostly above that of nickel-nickel oxide (+1.0 < NNO < + 1.9), although less oxidized conditions are estimated for the trondhjemite (– 0.5 < NNO < + 1.0). High water content was estimated for the sanukitoid-related granitoids (> 5%) relative to the TTG-affinity granitoids (< 4%) using amphibole-based water calibrations. Compared with sanukitoids from other Archean cratons, the Ourilândia sanukitoids crystallization constraints show similarities with the more oxidized members from the Baltic Shield, the Closepet-type granites and the Matok-type sanukitoids but differ from the reduced redox conditions of the Elan-type granitoids from the East Sarmatian orogen.

Genesis, geochemical evolution and metallogenic implications of magnetite: Perspective from the giant Cretaceous Atlas porphyry Cu–Au deposit (Cebu, Philippines)

The Atlas porphyry Cu–Au deposit (PCD) in central Cebu Island (Philippines) has a proven ore reserve of 1420 Mt @ 0.45% Cu, 0.24 g/t Au, 0.018 g/t Mo, and 1.8 g/t Ag. The PCD is characterized by four generations (Mag1 to Mag4) of magnetite, a mineral that can record the chemical evolution of the magmatic-hydrothermal system. The magmatic Mag1 is characterized by being euhedral with ilmenite lamellae formed by the oxy-exsolution process. The well-developed microporosity and 120° triple junction suggest that Mag2 has been modified by recrystallization or dissolution-reprecipitation process. The Mag3 (from the early-ore Stage I) is well-porous with almost no oxy-exsolution ilmenite lamellae. The Mag4 is from the late-ore Stage II in which the Mag4a has distinctive zoning formed by massive cavities, whereas the Mag4b has only a few pores. LA-ICP-MS trace element (esp. Ti and V) compositions indicate that the formation temperatures decrease from Mag1a to Mag3, then increase from Mag3 to Mag4a, and eventually decrease from Mag4a to Mag4b. On the contrary, oxygen fugacity (fO2) decreases from Mag1a to Mag3 but increases from Mag3 to Mag4, suggesting two magmatic-hydrothermal pulses driven by the Lutopan porphyry intrusion at Atlas. This is consistent with the development of two mineralization styles at Atlas, i.e., high fO2 magnetite mineralization and the subsequent giant Atlas porphyry Cu–Au mineralization.

High Purity Magnetite Microparticles Directly Derived from Mill Scale via Hydrogen-Reduction Method

This study develops a fast and simple way to produce high purity magnetite (Fe3O4) microparticles from mill scale by using hydrogen reduction with the addition of vapour as a retarding agent. By optimising the reduction temperature and gas flow rate, the characterisations by X-ray diffractometry technique shown that the Fe3O4 fraction of over 93 wt.-% is shown at the reduction temperature of 550 – 650 oC with the flow rate of the 4.5-5.5 mol%H2 + Ar gas + H2O gas mixture from 100 – 200 ml/min. The highest Fe3O4 fraction of over 99 wt.-% can be achieved from the reduction with the mixed gas at 650 oC and the flow rate of 200 ml/min for 4 hour.

Indoor particulate air pollution from open fires and the cognitive function of older people

Exposure to indoor air pollution is known to affect respiratory and cardiovascular health, but little is known about its effects on cognitive function. We measured the concentrations and magnetite content of airborne particulate matter (PM) in the indoor environment arising from burning peat, wood or coal in residential open fires. Highest indoor PM2.5 concentrations (60 μg/m3 i.e. 2.4 times the WHO-recommended 24-h mean) occurred when peat was burned, followed by burning of coal (30 μg/m3) and wood (17 μg/m3). Conversely, highest concentrations of coarser PM (PM10-2.5) were associated with coal burning (20 μg/m3), with lower concentrations emitted during burning of wood (10 μg/m3) and peat (8 μg/m3). The magnetic content of the emitted PM, greatest (for both PM size fractions) when coal was burned, is similar to that of roadside airborne PM. Exposure to PM, and to strongly magnetic airborne PM, can be greater for individuals spending ~5 h/day indoors with a coal-burning open fire for 6 months/year compared to those commuting via heavily-trafficked roads for 1 h/day for 12 months/year. Given these high indoor PM and magnetite concentrations, and the reported associations between (outdoor) PM and impaired neurological health, we used individual-level data from The Irish Longitudinal Study on Ageing (TILDA) to examine the association between the usage of open fires and the cognitive function of older people. Using a sample of nearly seven thousand older people, we estimated multi-variate models of the association between cognitive function and open fire usage, in order to account for relevant confounders such as socio-economic status. We found a negative association between open fire usage and cognitive function as measured by widely-used cognitive tests such as word recall and verbal fluency tests. The negative association was largest and statistically strongest among women, a finding explained by the greater exposure of women to open fires in the home because they spent more time at home than men. Our findings were also robust to stratifying the sample between old and young, rich and poor, and urban and rural.

Source apportionment of magnetite particles in roadside airborne particulate matter

Exposure to airborne particulate matter (PM) is associated with pulmonary, cardiovascular and neurological problems. Magnetite, a mixed Fe2+/Fe3+ oxide, is ubiquitous and abundant in PM in urban environments, and might play a specific role in both neurodegeneration and cardiovascular disease. We collected samples of vehicle exhaust emissions, and of heavily-trafficked roadside and urban background dusts from Lancaster and Birmingham, U.K. Then, we measured their saturation magnetic remanence and used magnetic component analysis to separate the magnetite signal from other contributing magnetic components. Lastly, we estimated the contributions made by specific traffic-related sources of magnetite to the total airborne magnetite in the roadside environment. The concentration of magnetite in exhaust emissions is much lower (3–14 x lower) than that in heavily- trafficked roadside PM. The magnetite concentration in petrol-engine exhaust emissions is between ~0.06 and 0.12 wt%; in diesel-engine exhaust emissions ~0.08–0.18 wt%; in background dust ~0.05–0.20 wt% and in roadside dust ~0.18–0.95 wt%. Here, we show that vehicle brake wear is responsible for between ~68 and 85% of the total airborne magnetite at the two U.K. roadside sites. In comparison, diesel-engine exhaust emissions account for ~7% - 12%, petrol-engine exhaust emissions for ~2% - 4%, and background dust for 6% - 10%. Thus, vehicle brake wear is by far the most dominant source of airborne magnetite in the roadside environment at the two sites examined. Given the potential risk posed, post-inhalation, by ultrafine magnetite and co-associated transition metal-rich particles to human cardiovascular and neurological health, the high magnetite content of vehicle brake wear might need to be reduced in order to mitigate such risk, especially for vulnerable population groups.

Fabrication of Fe3O4/O‐Carboxylmethyl Chitosan Magnetic Particle Assembles in Inverse Miniemulsions for Loading and Release of Bovine Serum Albumin

AbstractFe3O4/O‐carboxylmethyl chitosan (OCMC) magnetic particle assembles (MPAs) with high magnetite loading and superparamagnetism were controllably prepared through Schiff base crosslinking reaction of OCMC‐stabilized Fe3O4 magnetic nanoparticles (OCMC‐Fe3O4 MNPs) in the dispersed phase of inverse miniemulsions. The Fe3O4/OCMC MPAs were composed of many tiny Fe3O4 MNPs, and they did not only inherit the good superparamagnetism of OCMC‐Fe3O4 MNPs, but also displayed high collective magnetic response to an external magnetic field. The crosslinked network of OCMC offered a good structural integrity of the Fe3O4/OCMC MPAs either in inverse emulsions or in aqueous dispersions within a wide pH range. The Fe3O4/OCMC MPAs displayed a reversible pH‐dependent loading and release behavior of a model protein, bovine serum albumin, exhibiting a great potential in functioning as nanocarriers for loading and release of biomacromolecules.