Sediment magnetic record of anthropogenic environmental changes in the catchment of a typical submerged macrophyte-dominated lake over the last approximately 168 years.

Impact of historical land use changes on lacustrine sedimentation recorded in varved sediments of Lake Jaczno, northeastern Poland

Sklodowskiej-Curie 34, 41-819 Zabrze 2) EU RTD project No. EVK2-CT-1999-00019 Abstract: Scientists need a fast and inexpensive method of estimating soil pollution in areas exposed to contamination by atmospheric pollutants of industrial and urban origin. One possible alternative to traditional chemical analyses is soil magnetometry. This method is based on the detection of magnetic particles that are introduced into the soil environment through wet or dry dustfall events. Magnetic particles are produced as a result of many technolog ical processes, but fossil fuel combustion is the most common source . Many trace elements are associated with magnetic particles and, under some condition may be liberated to the soil or ground water in forms and quantities that are potentially toxic. Magnetic proxies are a useful tool for mapping areas contaminated by industrial emission. The regional large scale of magnetic mapping over the Central Europe (Schwarzwald - Bavarian Alps - Northern Austria - Bohemia - Lower and Upper Silesia) was initiated in the frame of EU MAGPROX Project. The map exhibit of the many existing local and regional " hot spots" that are the result of geological background (mostly in Alps) and anthropogenic influx (industrial and urban dust fall). The large anthropogenic anomalies were identified in Upper and Lower Silesia (South Poland), eastern Saxony and Brandenburgy, Northern Bohemia and Northern Moravia (Ostrava region). The detailed mapping of anomaly areas show the variability of susceptibility with many local maxima, which are in close correlation with heavy metals and many other pollutants concentration and precisely points out the places of potential environmental hazards.

Diagenetic analysis of shallow and deep-seated gas hydrate systems from the Bay of Bengal

Magnetic withdrawal of particles for multiple purposes in nuclear power plants

Numerical study on targeted delivery of magnetic drug particles in realistic human lung

Understanding the sources of sediments deposited in tidal flats is critical for reconstructing the evolution of coastal regions impacted by large rivers. Environmental magnetism can be an effective tool to track sediment sources and analyze the sediment properties. We evaluate several magnetic parameters from the tidal flat sediments along the Jiangsu coast. The results show that the sediments of Liandao Island have the lowest values of magnetic susceptibility (χ), anhysteretic remanent magnetization (ARM) and saturation isothermal remanence magnetization (SIRM). In addition to these, the values of χ, ARM and SIRM display a generally increasing trend from the north to the south along the Jiangsu coast. The strong relations between χ, ARM and SIRM show that the changes of magnetization of the tidal flat sediments mainly reflect the changes of concentration rather than those in grain sizes of magnetic particles. The main magnetic phase is magnetite, with a small amount of hematite. The strong relationship between χ and the 2-16 μm grain-size fraction suggests that magnetite is enriched in the finer silt fraction. The sediment sources is the main factor that influences the magnetic properties of the tidal flat sediments from the Jiangsu coast. Combined with the previous studies, the results indicate that the tidal flat sediments of Liandao Island were mainly derived from the nearshore rock weathering. The Yellow River is the dominant supplier for the north of Dafeng, while the Yangtze River is the dominant supplier for the south of Rudong. The coast between Dafeng and Rudong is a transition zone influenced by both rivers. This study provides a basis against which possible future variations in sediment composition resulting from catchment changes can be assessed.

Separation and trapping of magnetic particles by insertion of ferromagnetic wires inside a microchip: Proposing a novel geometry in magnetophoresis

Soil is composed of different types of particles which are either natural or of anthropogenic origin. Anthropogenic particles are often related to the presence of heavy metals and thus provide information on soil quality. Magnetic parameters can detect the presence of such particles and may be used as a proxy for environmental pollution. This study explores the relationships between magnetic particles and the nematofauna of agricultural soils. Magnetic, pedological, microscopy and nematological analyses were conducted in soils collected from major regions of potato production in Portugal. The magnetic characterisation of soils identified regions with magnetic particles with possible anthropogenic origin. Microscopy analysis revealed the presence of spherical particles dominantly composed of Fe, O and C. A positive and significant relationship was found between saturation isothermal remanent magnetisation (SIRM) and mass-specific susceptibility (χ), confirming the importance the ferrimagnetic fraction to magnetic properties. The nematode communities were composed of nematodes belonging to four trophic groups (bacterial feeding, plant feeders, fungal feeders and omnivores/predators). The relationships between magnetic parameters and the nematodes showed that (1) S-25 has a linear correlation with number of nematodes per kilogram of soil and with plant feeders' trophic group and (2) SIRM correlates with the bacterial feeders trophic group. This study reveals that magnetic proxies may provide means for detecting regions with higher levels of pollution, possibly related to heavy metals. Due to the large background variability found in magnetic parameters, the sampling spacial mesh should to be further refined and the input of magnetic minerals needs to be locally calibrated.

Magnetic particles (MPs) are known to respond to a magnetic field and can be moved by magnetic force, which make them good carriers in bioengineering and pharmaceutical engineering. In this paper, a pose control method for the straight chain composed of MPs is proposed, and the chain with one pose can be moved to another position with another pose using alternately employed uniform and gradient magnetic fields. Based on computer simulations, it is revealed that in the uniform magnetic field, the MPs form a straight chain with the same separation space along the field lines, and once the uniform magnetic field rotates, the chain also rotates with the field. In the gradient magnetic field, the MPs move toward the higher field so that the translation of the chain can be realized. The simulation results indicate that while the uniform magnetic field is rotating, there exists certain hysteresis between the chain and the field, and the chain is not straight anymore. So the uniform magnetic field should rest at the target angle for a period to make the chain fully relax to be straight. For nanoMP, its magnetic moment directly determines the gradient magnetic force which is much smaller than the dipole–dipole force among MPs. Therefore, the translation of the chain is much more time-consuming than rotation. To enlarge the translational velocity, it is suggested to increase the size of MPs or the magnetic field gradient.

Magnetic Abrasive Finishing (MAF) is one of the non-conventional finishing processes, which produces a high level of surface quality and is primarily controlled by magnetic field. In MAF, workpiece is kept between the two poles (N and S) of a magnet. The working gap between the workpiece and the magnet is filled with magnetic abrasive particles. A magnetic abrasive flexible brush (MAFB) is formed, acting as a multipoint cutting tool, due to the effect of magnetic field in the working gap. This paper deals with theoretical investigations of the plane MAF process to know the effect of the process parameters on the surface quality produced. The magnetic field is simulated using finite element model of the process. The magnetic field is also measured experimentally to validate the theoretical results. A series of numerical experiments are performed using the finite element and surface roughness models of the process to study the effect of flux density, height of working gap, size of magnetic abrasive particles and slots (size and location) in the magnetic pole on the surface quality. Based on the results, it is concluded that surface roughness value (R max ) of the workpiece decreases with increase in flux density and size of magnetic abrasive particles. Surface roughness value (R max ) decreases with decrease in working gap. R max value also decreases when the magnet has a slot as compared to the magnet having no slot. Present study would help in understanding the effect of the various parameters on surface roughness value without doing a number of real-life experiments.

A chemical characterization of the surficial sediment (0–20 cm) of type ‘dy’ (org-Cpart/TNpart> 10) of the anthropogenically polluted shallow Lake Petersdorf is presented. Eighty samples were analyzed for a set of parameters, i.e. dry weight, loss on ignition (LOI), total inorganic carbon (TIC), N, S, P, Ca, Si, As, Fe, Al, Mn, Zn, Cd, and Pb. LOI, TIC, N, S, Ca, P, and Zn tend to accumulate at a water depth >2 m (70.6% of the lake surface) in contrast to Mn and Fe which are more widely distributed, and Cd and Pb which are accumulated in the lake part close to a road. The enrichment factors of certain elements, e.g. Al (23.9%), Si (31.5%), P (12.2%), and Ca (68.7%) from 20 cm sediment depth up to the surface, are attributed to incisive changes in the immediate catchment. Erosion, fertilization, amelioration, and separation of the peatland north of the lake by a dam within the last 60 yrs resulted in the change of Lake Petersdorf from a dystrophic to a eutrophic stage. This enhanced the mineralization of its meso-humic (LOI/TNpart=20.6) sediment.

Chain formation mechanism of magnetic particles in magnetorheological elastomers during pre-structure

Single-cell analysis is an emerging discipline that has shown a transformative impact in cell biology in the last decade. Progress in this field requires systems capable of accurately moving the cells and particles in a controlled manner. Here, we present a microfluidic platform equipped with C-shaped magnetic thin films to precisely transport magnetic particles in a tri-axial rotating magnetic field. This innovative system, compared to the other rivals, offers numerous advantages. The magnetic particles repel each other to prevent undesired cluster formation. Many particles move synced with the external rotating magnetic field, which results in highly parallel controlled particle transport. We show that the particle transport in this system is analogous to electron transport and Ohm’s law in electrical circuits. The proposed magnetic transport pattern is carefully studied using both simulations and experiments for various parameters, including the magnetic field characteristics, particle size, and gap size in the design. We demonstrate the appropriate transport of both magnetic beads and magnetized living cells. We also show a pilot mRNA-capturing experiment with barcode-carrying magnetic beads. The introduced chip offers fundamental potential applications in the fields of single-cell biology and bioengineering.

Simulation of water purification using magnetically ultra-responsive micro- and nanoscavengers

Magnetic particles are widely used in biological research and bioanalytical applications. As the corresponding tools are progressively being miniaturized and integrated, the understanding of particle dynamics and the control of particles down to the level of single particles become important. Here, we describe a numerical model to simulate the dynamic behavior of ensembles of magnetic particles, taking account of magnetic interparticle interactions, interactions with the liquid medium and solid surfaces, as well as thermal diffusive motion of the particles. The model is verified using experimental data of magnetic field-induced disaggregation of magnetic particle clusters near a physical surface, wherein the magnetic field properties, particle size, cluster size, and cluster geometry were varied. Furthermore, the model clarifies how the cluster configuration, cluster alignment, magnitude of the field gradient, and the field repetition rate play a role in the particle disaggregation process. The simulation model will be very useful for further in silico studies on magnetic particle dynamics in biotechnological tools.