Biomagnetism

Computational studies of the head utilizing finite element models (FEMs) have been used to investigate a wide variety of brain-electromagnetic (EM) field interaction phenomena including magnetic stimulation of the head using transcranial magnetic stimulation (TMS), direct electric stimulation of the brain for electroconvulsive therapy, and electroencephalography source localization. However, no human head model of sufficient complexity for studying the biophysics under these circumstances has been developed which utilizes structures at both the regional and cellular levels and provides well-defined smooth boundaries between tissues of different conductivities and orientations. The main barrier for building such accurate head models is the complex modeling procedures that include 3D object reconstruction and optimized meshing. In this study, a structurally detailed finite element model of the human head was generated that includes details to the level of cerebral gyri and sulci by combining computed tomography and magnetic resonance images. Furthermore, cortical columns that contain conductive processes of pyramidal neurons traversing the neocortical layers were included in the head model thus providing structure at or near the cellular level. These refinements provide a much more realistic model to investigate the effects of TMS on brain electrophysiology in the neocortex.

A novel transcranial magnetic stimulation (TMS) device with controllable pulse width (PW) and near-rectangular pulse shape (cTMS) is described. The cTMS device uses an insulated gate bipolar transistor (IGBT) with appropriate snubbers to switch coil currents up to 6 kA, enabling PW control from 5 s to over 100 s. The near-rectangular induced electric field pulses use 2%-34% less energy and generate 67%-72% less coil heating compared to matched conventional cosine pulses. CTMS is used to stimulate rhesus monkey motor cortex in vivo with PWs of 20 to 100 s, demonstrating the expected decrease of threshold pulse amplitude with increasing PW. The technological solutions used in the cTMS prototype can expand functionality, and reduce power consumption and coil heating in TMS, enhancing its research and therapeutic applications.

The energy absorption mechanism in the close near Eeld of dipole antennas is studied by numerical simulations. All computations are performed and validated applying the threedimensional multiple multipole (3DMMP) software package. The numerical model of the plane phantom is additionally checked by accurate as possible experimental measurements. For the plane phantom, the interaction mechanism can be well described by H-Eeld induced surface currents. The spatial peak specific absorption rate (SAR) can be approximated within 3 dB by a formula given here based on the incident H-field or antenna current and on the conductivity and permittivity of the tissue. It is further shown that these findings can be generalized to heterogeneous tissues and larger biological bodies of arbitrary shape for frequencies above 300 MHz. The SAR is found to be mainly proportional to the square of the incident If-Eeld, which implies that in the close near field, the spatial peak SAR is related to the antenna current and not to the input power. Another consequence of this study is that the exclusion clause of the ANSI C95.1-1982 standard for low-power communication equipment must be revised because it is in direct contradiction with the basic peak SAR limits.

Both human and non-human living organisms have traditionally been viewed and studied as material organisms. Within this context, life has been defined by the biochemical processes that sustain the living organisms, while mind and consciousness have been relegated to functions within the brain. Yet the body is just a complex pattern of energetic material particle exchanges to physicists when compared to the biochemical processes studied by chemists and biologists. As the scientific view of life has expanded beyond these early limits, new research has centered more upon the electric, magnetic and electromagnetic characteristics of living material bodies as well as the brain, but the overall concept of life has not kept pace or changed at all. Once these new research efforts have been taken into account, it is easy to demonstrate that life, or rather the “living force” as it was once called, can be equated to the overall matter/energy pattern of the organism, while mind and consciousness can be equated to the electric and magnetic counterparts of the matter/energy pattern of living organisms. Doing so does nothing to disrupt or disturb the current thinking that the ‘process of life’ is purely biochemical. In fact, all living organisms, from the simplest one-celled organism to the most complex living organism known, a human,  are extremely complex material/energy patterns (comprising the structural and biochemical body) superposed by the extremely complex electric (electromagnetic scalar potential) field patterns and magnetic (electromagnetic vector potential) field patterns that constitute minds and consciousness. As humans, we may have the most complex and advanced mind and consciousness, but all other living organisms display mind and consciousness at various lower levels than our human mind and consciousness. The brain alone should no longer be considered the sole source and home of mind and consciousness. Mind and consciousness have mistakenly become associated with the brain and no other part of the body because of the dense concentration of neurons in the brain, a fact which can only be understood by studying the electric and especially the magnetic characteristics of the neuron. A strict study of the magnetic (electromagnetic vector potential) field patterns associated with neurons and neural nets demonstrates how thoughts and streams of thought originate in the brain and are stored magnetically at and within the points in space-time occupied by the brain and body. Microtubules, which act as magnetic induction coils, are the primary structural bio-unit used for building, storing and retrieving memories in the mind. In a very strict sense of the concepts, mind and consciousness could be considered a mixed four-dimensional electric-magnetic potential field holographic body that maintains a semi-independent existence with the material/energy field or structural/biochemical body of every living organism. The consequences of this physical model of mind and consciousness are revolutionary and imply a physical basis for (Darwinian) evolution as well as simple explanations of many paranormal phenomena, including the survival of mind and consciousness after death of the material body.

If the Biofield is a true physical field, it must be fundamental to the very structure of physical reality, but the Biofield (LIFE or that which goes beyond the normal biologically explained living system) does not have a specific force associated with it as do other physical fields. Life evolved from chemical reactions that depended upon the four natural forces which were already in place before life evolved, so there must be more to LIFE than these simple known physical forces. LIFE (the Biofield) has the structural qualities of a field, but it is passive, not dynamically active like gravity, electricity and magnetism, so LIFE is either a structural entity or a fundamental construction within the very fabric of physical reality. Under these circumstances, LIFE (the Biofield) can be equated to the matter/energy field in a type of quantized space-time continuum, MIND to the corresponding electric field and CONSCIOUSNESS to the resulting magnetic field. The Biofield must be a product or an extension of if not a specific structural configuration within a five-dimensional single unified field that combines gravity and electromagnetism. As such, the Biofield can be easily described by a modified Einstein-Kaluza five-dimensional model that describes our experiential quantized space-time continuum.

This paper describes a complementary Kalman filter design to estimate orientation of human body segments by fusing gyroscope, accelerometer, and magnetometer signals from miniature sensors. Ferromagnetic materials or other magnetic fields near the sensor module disturb the local earth magnetic field and, therefore, the orientation estimation, which impedes many (ambulatory) applications. In the filter, the gyroscope bias error, orientation error, and magnetic disturbance error are estimated. The filter was tested under quasi-static and dynamic conditions with ferromagnetic materials close to the sensor module. The quasi-static experiments implied static positions and rotations around the three axes. In the dynamic experiments, three-dimensional rotations were performed near a metal tool case. The orientation estimated by the filter was compared with the orientation obtained with an optical reference system Vicon. Results show accurate and drift-free orientation estimates. The compensation results in a significant difference (p 0 01) between the orientation estimates with compensation of magnetic disturbances in comparison to no compensation or only gyroscopes. The average static error was 1.4 (standard deviation 0.4) in the magnetically disturbed experiments. The dynamic error was 2.6 root means square.

Epidemiological evidence demonstrates an increase in acute lung injury associated with electronic cigarettes use (vaping) in North America (excluding Alaska) over the past several months. The cause (etiological agent) and mechanism of vaping-associated acute lung injury remains to be determined. Electronic cigarettes are predominately made using iron alloy-vaping coils (with varying iron content), which aerosolize electronic cigarette liquid via heating. Recent evidence demonstrated significantly elevated levels of iron in electronic cigarette/vape tanks and aerosols, suggesting lung exposure to iron in individuals that use electronic cigarettes/vapes. Pathological analysis of lung tissues from patients with acute lung disease following use of electronic cigarettes/vapes, demonstrated that the lung damage resembles "chemical burns", which was associated with the presence of brown and black pigmented particles in foamy-lung macrophages. In this publication, it is proposed that the brown pigmented particles in foamy-lung macrophages is ferric iron in ferritin (hemosiderin), which results in a brownish pigmentation in tissues. It is also proposed that the black particles in the foamy-lung macrophages are iron oxides, such as magnetite-a black rock mineral. A novel hypothesis is proposed in which iron in electronic cigarettes/vapes aerosols are deposited in the lungs via inhalation, and converted to iron oxides via highly exothermic oxidation, resulting in chemical burns. This publication proposes that oxidation of iron to iron oxides in the lungs of North Americans is mediated via very low frequency (radio)-electromagnetic waves emanating from the lithosphere in North America. Consistent with this hypothesis, the magnetic field of the lithosphere is predominantly induced by iron oxides (such as magnetite) in the Earth's crust, and recent evidence demonstrates that the lithosphere magnetic field of North America (excluding Alaska) is currently exhibiting increasing excitation compared to Western Europe, which has similarly high levels of electronic cigarette/vape users. Consequently, the current dynamics of the lithosphere magnetic field reconciles the spatiotemporal epidemiology of vaping-associated acute lung injury. Per the current dynamics of the lithosphere magnetic field, this publication predicts that the current wave of vaping-associated lung injury will continue to rapidly decay, and re-emerge in the coming years with similar oscillatory temporal dynamics and geographic restriction to North America (excluding Alaska). This publication predicts that Perls' Prussian blue dye staining of lung sections from patients with vaping-associated acute lung injury will detect the presence of iron (ferric ions) in the lung. Furthermore, scanning transmission electron microscopy examination of the injured lung tissues will detect various iron oxides species.

Exposure of rat (n=7) brain to permanent magnetic field (PMF) was imposed by two bitemporally placed magnets. The direction of the magnetic induction vector was altered by replacing the poles of magnets at both sides of the head. Four different configurations of pole pairs were tested: S-N, N-S, S-S and N-N (where S-south and N-north pole of magnet). The preliminary studies demonstrated that the magnetic field prolonged the latency of the peaks of somato-sensory evoked potentials, reflecting a delay in the impulse propagation in the central nervous system. This effect was pronounced when the north pole was on the right side and at the south pole at the left side. In contrast, the poles was both changed there was a tendency of impulse propagation acceleration, however this effect did not reach the statistically significant level. Prolongation of the latencies was also seen when north poles was placed at both sides of the head. Our results indicate that, at the same magnetic field induction the direction of the magnetic induction vector has significant effect on nervous system activity.

ENRICHMENT of the ferrimagnetic minerals magnetite and maghemite is frequently observed in the top layer of soil horizons1–5. Although both inorganic6,7 and organic8,9processes are known to produce magnetite, magnetite in soils has been ascribed to an inorganic origin6. We report here the discovery of living magnetic bacteria, similar to those found in salt- and fresh-water sediments8,10–2, in the A horizon of a well developed soil profile in a typical meadow environment in southern Bavaria. The bacteria were detected in fresh samples using an optical microscope equipped with a rotating magnetic field13 and a volumetrically calibrated depression slide, permitting accurate counts of the volume density of the organisms. We suggest that magnetic bacteria and their magnetofossils14 can contribute to the magnetic properties of soils.



References 1. Le Borgne, E. Ann. Geophys. 11, 399−419 (1955).
2. Mullins, C. E. J. Soil Sci. 28, 223−246 (1977). | ISI | ChemPort |
3. Schwertmann, U. & Heinemann, B. Neues Jb. Miner. Mh. 8, 174−181 (1959).
4. Stanjek, H. Z. Pflanzenernähr. Bodenkunde 150, 314−318 (1987). | ChemPort |
5. Fine, P., Singer, M. J., La Ven, R., Verosub, K. & Southard, R. J. Geoderma 44, 287−306 (1989). | Article | ChemPort |
6. Maher, B. A. & Taylor, R. M. Nature 336, 368−370 (1988). | Article | ChemPort |
7. Taylor, R. M., Maher, B. A. & Self, P. G. Clay Miner. 22, 411−422 (1987). | ChemPort |
8. Blakemore, R. P. A. Rev. Microbiol. 36, 217−238 (1982). | Article | ISI | ChemPort |
9. Lovley, D. R., Stolz, J. F., Nord, G. L. & Philips, E. J. P. Nature 330, 252−254, 1987. | Article | ISI | ChemPort |
10. Vali, H., Förster, O., Amarantidis, G. & Petersen, N. Earth planet. Sci. Lett. 86, 389−400 (1987). | Article |
11. Frankel, R. B., Blakemore, R. P., Torres de Aranjo, F. F. Esquival, D. M. S. & Danon, J. Science 212, 1269−1270 (1981).
12. Kirschvink, J. L. J. exp. Biol. 86, 345−347 (1980).
13. Petersen, N., Weiss, D. G. & Vali, H. Geomagnetism and Palaeomagnetism (eds Lowes, F. J. et al.) 231−241 (Kluver, Dordrecht, 1988).
14. Kirschvink, J. L. & Chang, S.-B. R. Geology 12, 559−562 (1984). | Article | ISI |
15. Maher, B. A. Phys. Earth planet. Inter. 42, 76−92 (1986). | Article | ISI |
16. Lowrie, G. W. & Fuller, M. J. geophys. Res. 76, 6339−6349 (1971). | ISI |
17. King, J., Banerjee, S. K., Marvin, J. & Özdemir, Ö. Earth planet. Sci. Lett. 59, 404−419 (1982). | Article | ISI |
18. Thompson, R. & Oldfield, F. Environmental Magnetism (Allen & Unwin, London, 1986).
19. Butler, R. F. & Banerjee, S. K. J. geophys. Res. 80, 4049−4058 (1975). | ISI | ChemPort |
20. von Dobeneck, T. Petersen, N. & Vali, H. Geowissenschaften in unserer Zeit 5, 27−35 (1987).
21. Petersen, N., von Dobeneck, T. & Vali, H. Nature 320, 611−615 (1986). | Article | ISI | ChemPort |
22. Schmidt, E. R. & Vermaas, F. H. S. Am. Mineral. 40, 422−431 (1955). | ChemPort |
23. Lovley, D. R., Stolz, J. F., Maher, B. A. & Taylor, R. M. Nature 340, 106 (1989). | Article | PubMed |
24. Vali, H. & Kirschvink, J. L. Nature 339, 203−206 (1989). | Article |
25. Gorby, Y. L., Beverridge, T. S. & Blakemore, R. P. J. Bact. 170, 834−841 (1988). | PubMed | ChemPort |
26. Mann, S., Frankel, R. B. & Blakemore, R. P. Nature 310, 405−407 (1984). | Article | ISI |
27. Vali, H. & Kirschvink, J. L. in Iron Biomineralization (eds Blackemore, R. P. & Frenkel, R. B.) (in the press).
28. Lethbridge, G. & Lynch, J. M. in Essays in Agricultural and Food Microbiology (Wiley, New York, 1987).

Magnetotactic bacteria (MTB), discovered in early 1970s contain single-domain crystals of magnetite (Fe 3 O 4 ) or greigite (Fe 3 S 4 ) called magnetosomes ranging from 35 to 120 nm in size. These crystals tend to form a chain like structure from the proximal to the distal pole along the long axis of the cell and align through an acidic protein mamJ to the bacterial cytoskeleton filament made out of actin-like protein mamK. The ability of these bacteria to sense the magnetic field, also called magnetotaxis, arises from the magnetic dipole moment of the entire chain of magnetosomes acting as a large magnet. Such organisms being facultatively anaerobic are able to sense the geomagnetic field and traverse the oxic-anoxic interface in aquatic habitats for optimal oxygen concentrations. Two aspects that are of particular interest are their phenomenal control of direction using magnetic field as well as the efficient displacement of selective nanoparticles. We aim to understand the efficacies of Magnetospirillum magneticum (AMB-1) in miniaturized semiconductor fabrication utilizing single and multi-walled carbon nanotubes.

This study investigates the apparent additive viscosity due to magnetic e!ects on the human blood. Experimental results show that blood #ow rate under gravity decreases by 30% when subjected to a high magnetic "eld of 10 T. The decrease in the #ow rate is due to an increase in the apparent viscosity of the blood due to the magnetic "eld. A correlation describing the viscosity of blood under these conditions is introduced which depends on the Langevin function and parameters.

During a routine anatomical dissection we discovered an aberrant muscle slip associated with the pectoralis
minor muscle that occurred bilaterally. The muscle slips originated from ribs five or six and inserted into the
tendon of the coracobrachialis in close proximity the coracoid process of the scapula. Fibers of the muscle slip
also blended with the pectoralis minor muscle on its lateral border. The muscle slips were innervated by the
medial pectoral nerve. Reports and documentation of anatomical variants such as this provide an important
resource for both researchers and clinicians.

Measurements of DC near biomagnetic fields are disturbed by low frequency noise, that are not reduced sufficiently by most of the magnetically shielded rooms or gradiometers. An effective SQUID based active shielding system has been developed and installed at the magnetically shielded rooms in the Biomagnetic Center of the University Jena to reduce external low frequency disturbances. A reduction of the magnetic noise of about 23 dB could be achieved at 50 mHz.

This paper proposes a simple statistical method for extracting target source activities from spatio-temporal source activities reconstructed from MEG measurements. The method requires measurements in a control condition, which contains only non-target source activities. The method derives, at each pixel location, an empirical probability distribution of the non-target source activity using the time course reconstruction obtained from the control period. The statistical threshold that can extract the target source activities is derived from the empirical distributions obtained from all pixel locations. Here, the multiple comparison problem is addressed with a two-step procedure involving standardizing these empirical distributions and deriving an empirical distribution of the maximum pseudo T value at each pixel location. The results of applying the proposed method to auditoryevoked measurements are presented to demonstrate the method's effectiveness. D

Electric fields and current densities induced in an anatomically realistic, high-resolution model of the human body are computed. The results are given for various organs in terms of average and maximum values for 60-Hz uniform magnetic fields in three orthogonal orientations. The effects of variations in the tissue conductivity are evaluated. The data presented can be linearly scaled to frequencies up to 100 kHz without an appreciable error, provided that the changes in tissue conductivity with frequency are taken into account. The scalar potential finite difference (SPFD) method with an appropriate matrix preconditioner and a conjugate gradient solver were used to model the problem. This approach resulted in a high computational efficiency that facilitated high-resolution (3.6 mm voxels) modeling involving 1 736 872 unknowns. All computations were performed on a Hewlett-Packard 9000/735 Unix workstation using under 200 MB of physical memory. Typical computation times were of the order of 25 h. The results show that conductivity variations, source orientation, and model realism can significantly affect the dosimetry values, particularly in comparison with more simplistic models. They also show that the maximum current density in several tissues can exceed 10 mA m 02 in a 60-Hz, 0.5-mT uniform magnetic field.

Nanoparticles are attracting considerable interest as contrast agents for many different imaging modalities. Moreover, imaging the events at the cellular and molecular level is possible by using nanoparticles that have the desired targeting moiety. Unfortunately, ultrasound imaging cannot visualize the nano-structures directly due to its limited spatial resolution and contrast. We present a new technique, pulsed magneto-acoustic imaging, capable of imaging magnetic nanoparticles indirectly. In this method, a high-strength pulsed magnetic field is used to induce motion within the magnetically labeled tissue and ultrasound is used to detect internal tissue motion. Experiments on tissue-mimicking phantoms and ex-vivo animal tissues demonstrated a clear contrast between normal and iron-laden samples labeled with 5 nm magnetic nanoparticles. In addition, the sensitivity of this new imaging technique was investigated for different concentrations of magnetic agents. The results of the study suggest that magnetic nanoparticles can be used as contrast agents in pulsed magnetoacoustic imaging. Furthermore, PMA imaging could become an imaging tool capable of visualizing the cellular and molecular composition of deep-lying structures.

This paper reviews some popular techniques to harvest energy for implantable biosensors. For each technique, the advantages and drawbacks are discussed. Emphasis is placed on the inductive links that are able to deliver power wirelessly through the biological tissues and enable bidirectional data communication with the implanted sensors. Finally, high-frequency inductive links are described, focusing also on the power absorbed by the tissues.

Epidemiological evidence demonstrates an increase in acute lung injury associated with electronic cigarettes use (vaping) in North America (excluding Alaska) over the past several months. The cause (etiological agent) and mechanism of vaping-associated acute lung injury remains to be determined. Electronic cigarettes are predominately made using iron alloy-vaping coils (with varying iron content), which aerosolize electronic cigarette liquid via heating. Recent evidence demonstrated significantly elevated levels of iron in electronic cigarette/vape tanks and aerosols, suggesting lung exposure to iron in individuals that use electronic cigarettes/vapes. Pathological analysis of lung tissues from patients with acute lung disease following use of electronic cigarettes/vapes, demonstrated that the lung damage resembles "chemical burns", which was associated with the presence of brown and black pigmented particles in foamy-lung macrophages. In this publication, it is proposed that the brown pigmented particles in foamy-lung macrophages is ferric iron in ferritin (hemosiderin), which results in a brownish pigmentation in tissues. It is also proposed that the black particles in the foamy-lung macrophages are iron oxides, such as magnetite-a black rock mineral. A novel hypothesis is proposed in which iron in electronic cigarettes/vapes aerosols are deposited in the lungs via inhalation, and converted to iron oxides via highly exothermic oxidation, resulting in chemical burns. This publication proposes that oxidation of iron to iron oxides in the lungs of North Americans is mediated via very low frequency (radio)-electromagnetic waves emanating from the lithosphere in North America. Consistent with this hypothesis, the magnetic field of the lithosphere is predominantly induced by iron oxides (such as magnetite) in the Earth's crust, and recent evidence demonstrates that the lithosphere magnetic field of North America (excluding Alaska) is currently exhibiting increasing excitation compared to Western Europe, which has similarly high levels of electronic cigarette/vape users. Consequently, the current dynamics of the lithosphere magnetic field reconciles the spatiotemporal epidemiology of vaping-associated acute lung injury. Per the current dynamics of the lithosphere magnetic field, this publication predicts that the current wave of vaping-associated lung injury will continue to rapidly decay, and re-emerge in the coming years with similar oscillatory temporal dynamics and geographic restriction to North America (excluding Alaska). This publication predicts that Perls' Prussian blue dye staining of lung sections from patients with vaping-associated acute lung injury will detect the presence of iron (ferric ions) in the lung. Furthermore, scanning transmission electron microscopy examination of the injured lung tissues will detect various iron oxides species.

We present a micromagnetic simulation for detection of magnetic labels modulated by an ac magnetic field. As the sensing element, spin valves with synthetic ferrimagnetic (SF) free and pinned layers are optimized. At lower fields, the sensors with SF free layers show linear transfer curves, demonstrating a coherent switching due to the strong antiferromagnetic coupling inside the SF free layers. The sensor offset field can be reduced by tuning the effective thickness of SF free and pinned layers. Magnetic simulation for the detection of 250-nm magnetic labels with this sensor shows a linear giant magnetoresistive signal dependence on the number of particles.

This work describes the construction and characterization of a new transducer dedicated to the susceptometrics and ultrasonic measurements of samples labeled with magnetic particles. This transducer, called magneto-acoustic, consists of a hybrid system formed by the junction of an Alternating Current Biosusceptometer (ACB) and an ultrasonic transducer. Its basic operation principle is the simultaneous measurement of the magnetization and the internal structure micro-vibrations of a medium labeled with magnetic particles when excited by an external alternating magnetic field generated by the ACB excitation coils. In vitro measurements were performed to support the prototype development and characterization presented in this work. The measurement technique employing this hybrid transducer was called vibromagnetoacoustography. The samples consisted of fluid medium labeled with magnetic tracers (ferrite micro particles of diameter ranging from 30 m and 70 m). It was evaluated the system response dependence with different physical parameters such as: base material viscosity in which ferromagnetic particles was mixed; the particles concentration in the base material; the oscillation frequency of the magnetic field excitation; the voltage applied on magnetizing coils and the distance between sample and transducers. The magneto-acoustic transducer response showed a better signal to noise ratio for magnetization frequency around 200 Hz and a 4% ferrite concentration. Above this concentration the base material viscosity changed disrupting the measurements. The responses of susceptometer and Doppler ultrasound have a linear dependence with the applied voltage level in the magnetizing coils and an quasi linear dependence with low ferromagnetic particles concentrations (4%). A repeatability test was also performed to the prototype which indicated a deviation of 0.94% and 0.25% in the Doppler and susceptometric measurements, respectively. The vibration measurement of ferromagnetic micro-particles performed in vitro, using a Doppler transducer, showed high sensitivity to low ferromagnetic material concentrations (~1%) immersed in a fluid medium.

ABSTRACT The detection of multiple cancer biomarkers in human serum plays an important role for early cancer detection and represents a challenge to the development of biosensing devices. Mucines are glycoproteins, expressed in physiological conditions on the surface of epithelial tissues with role in lubrication. Several studies showed the implication of mucins (e.g. MUC1, MUC4) in the pathogenesis of ovarian cancer. This paper reviews the preliminary results of a few approaches performed in our laboratory for the design of immunosensors for mucines tumor markers detection using various immobilization platforms. Different strategies have been employed using magnetic nanobeads and conducting polymer/multiwall carbon nanotube composite films for the immobilization of the capturing antigen.

The purpose of this study is to investigate the potential of magnetic nanoparticles for enhancing drug delivery using a low oscillating magnetic field (OMF) strength. We investigated the ability of magnetic nanoparticles to cause disruption of a viscous biopolymer barrier to drug delivery and the potential to induce triggered release of drug conjugated to the surfaces of these particles. Various magnetic nanoparticles were screened for thermal response under a 295-kHz OMF with an amplitude of 3.1 kA/m. Based on thermal activity of particles screened, we selected the nanoparticles that displayed desired characteristics for evaluation in a simplified model of an extracellular barrier to drug delivery, using lambda DNA/HindIII. Results indicate that nanoparticles could be used to induce DNA breakage to enhance local diffusion of drugs, despite low temperatures of heating. Additional studies showed increased diffusion of quantum dots in this model by singleparticle tracking methods. Bimane was conjugated to the surface of magnetic nanoparticles. Fluorescence and transmission electron microscope images of the conjugated nanoparticles indicated little change in the overall appearance of the nanoparticles. A release study showed greater drug release using OMF, while maintaining low bulk heating of the samples (T = 30 • C). This study indicates that lower magnetic field strengths may be successfully utilized for drug delivery applications as a method for drug delivery transport enhancement and drug release switches.

This paper presents a novel technique for bacteria detection. The proposed system uses MC-1 magnetotactic bacteria and measures impedance to detect the presence of pathogenic bacteria. An electrode array is connected to respective cells that are fully integrated for impedance detection. The simulated performance shows that the circuit that was designed is robust. It can detect impedances ranging from about 3KΩ to at least 100MΩ. The only limits that we have for detecting large impedances are the operation frequencies and leakage currents. The circuit is thus very robust and can adapt to a wide range of uncertainty.

The energy absorption mechanism in the close near Eeld of dipole antennas is studied by numerical simulations. All computations are performed and validated applying the threedimensional multiple multipole (3DMMP) software package. The numerical model of the plane phantom is additionally checked by accurate as possible experimental measurements. For the plane phantom, the interaction mechanism can be well described by H-Eeld induced surface currents. The spatial peak specific absorption rate (SAR) can be approximated within 3 dB by a formula given here based on the incident H-field or antenna current and on the conductivity and permittivity of the tissue. It is further shown that these findings can be generalized to heterogeneous tissues and larger biological bodies of arbitrary shape for frequencies above 300 MHz. The SAR is found to be mainly proportional to the square of the incident If-Eeld, which implies that in the close near field, the spatial peak SAR is related to the antenna current and not to the input power. Another consequence of this study is that the exclusion clause of the ANSI C95.1-1982 standard for low-power communication equipment must be revised because it is in direct contradiction with the basic peak SAR limits.

Magnetotactic bacteria (MTB) can be controlled by an externally applied magnetic field. Their fast migration speed and quick response time, along with their capability to achieve 4 pN thrust force, make them well suited for micro-bio-actuators and bio-carriers. Here, we use conventional methods of microlithographyto construct a microfluidic device to evaluate the activity of MTB in microchannels. Experiments also prove

We report a novel method for identifying the small intestine electrical activity slow wave frequencies from noninvasive biomagnetic measurements. Superconducting QUantum Interference Device (SQUID) magnetometer measurements are pre-processed to remove baseline drift and high frequency noise. Subsequently, the underlying source signals are separated using the well-known SOBI algorithm. A simple classification scheme identifies and assigns some of the SOBI components to a section of small bowel. Slow wave frequencies were clearly identified in 10 out of 12 test subjects to within 0.09-0.25 cycles per minute. The method is sensitive at the 40.3-55.9% level, while false positive rates were 0-8.6%. This technique could potentially be used to help diagnose gastrointestinal ailments and obviate some exploratory surgeries.

Biomagnetic monitoring of atmospheric pollution is a growing application in the field of environmental magnetism. Particulate matter (PM) in atmospheric pollution contains readily measurable concentrations of magnetic minerals. Biological surfaces, exposed to atmospheric pollution, accumulate magnetic particles over time, providing a record of location-specific, time-integrated air quality information. This review summarizes current knowledge of biological material (“sensors”) used for biomagnetic monitoring purposes. Our work addresses the following: the range of magnetic properties reported for lichens, mosses, leaves, bark, trunk wood, insects, crustaceans, mammal and human tissues; their associations with atmospheric pollutant species (PM, NOx, trace elements, PAHs); the pros and cons of biomagnetic monitoring of atmospheric pollution; current challenges for large-scale implementation of biomagnetic monitoring; and future perspectives. A summary table is presented, with the aim ...

This paper deals with the benefits of using a nonlinear model-based approach for controlling magnetically guided therapeutic microrobots in the cardiovascular system. Such robots used for minimally invasive interventions consist of a polymer binded aggregate of nanosized ferromagnetic particles functionalized by drug-conjugated micelles. The proposed modeling addresses wall effects (blood velocity in minor and major vessels' bifurcations, pulsatile blood flow and vessel walls, and effect of robot-to-vessel diameter ratio), wall interactions (contact, van der Waals, electrostatic and steric forces), non-Newtonian behaviour of blood and different driving designs as well. Despite nonlinear and thorough, the resulting model can both be exploited to improve the targeting ability and be controlled in closed-loop using nonlinear control theory tools. In particular, we infer from the model an optimization of both the designs and the reference trajectory to minimize the control efforts. Efficiency and robustness to noise and model parameter's uncertainties are then illustrated through simulations results for a bead pulled robot of radius 250µm in a small artery.

Submicrometer Hall sensors, with Hall cross width of 250 nm, were fabricated from InAs/AlSb quantum well semiconductor heterostructures. The room-temperature device characteristics were examined by experimental Hall effect and electronic noise measurements combined with analytical calculations. The noise-equivalent magnetic moment resolution of the order of 10 4

Several animals and microbes have been shown to be sensitive to magnetic fields, though the exact mechanisms of this ability remain unclear in many animals. Chitons are marine molluscs which have high levels of biomineralised magnetite coating their radulae. This discovery led to persistent anecdotal suggestions that they too may be able to navigationally respond to magnetic fields. Several researchers have attempted to test this, but to date there have been no largescale controlled empirical trials. In the current study, four chiton species (Katharina tunicata, Mopalia kennerleyi, Mopalia muscosa and Leptochiton rugatus, n = 24 in each) were subjected to natural and artificially rotated magnetic fields while their movement through an arena was recorded over four hours. Field orientation did not influence the position of the chitons at the end of trials, possibly as a result of the primacy of other sensory cues (i.e. thigmotaxis). Under non-rotated magnetic field conditions, the orientation of subjects when they first reached the edge of an arena was clustered around 309-345°(northnorth-west) in all four species. However, orientations were random under the rotated magnetic field, which may indicate a disruptive effect of field rotation. This pattern suggests that chitons can detect and respond to magnetism.

A mathematical model was used to simulate magnetic stimulation on a mammalian myelinated axon. The capacitance and resistance of the stimulator and the coil geometry were utilized as parameters for optimizing the efficiency of magnetic stimulation. Results showed that the optimal coil design required the minimum inner radius and height, and therefore a pancake-like coil was more efficient for magnetic stimulation. Such an argument was valid for both the infinite and the semi-infinite axons. A stimulator with smaller resistance as well as capacitance was able to provide more efficient magnetic stimulation

We investigate the effect of tissue heterogeneity and anisotropy on the electric field and current density distribution induced in the brain during magnetic stimulation. Validation of the finite-element (FE) calculations in a homogeneous isotropic sphere showed that the magnitude of the total electric field can be calculated to within an error of approximately 5% in the region of interest, even in the presence of a significant surface charge contribution. We used a high conductivity inclusion within a sphere of lower conductivity to simulate a lesion due to an infarct. Its effect is to increase the electric field induced in the surrounding low conductivity region. This boost is greatest in the vicinity of interfaces that lie perpendicular to the current flow. For physiological values of the conductivity distribution, it can reach a factor of 1.6 and extend many millimeters from the interface. We also show that anisotropy can significantly alter the electric field and current density distributions. Either heterogeneity or anisotropy can introduce a radial electric field component, not present in a homogeneous isotropic conductor. Heterogeneity and anisotropy are predicted to significantly affect the distribution of the electric field induced in the brain. It is, therefore, expected that anatomically faithful FE models of individual brains which incorporate conductivity tensor data derived from diffusion tensor measurements, will provide a better understanding of the location of possible stimulation sites in the brain.

ABSTRACT This work presents an experimental procedure involving susceptometric measurement of a fluid labeled with nanoparticles magnetic and, simultaneously, the detection of vibration of these nanoparticles by an ultrasound. This vibration was generated by the action of alternating magnetizing field from susceptometric system. Measurements was performed in a paraffin gel phantom with a spherical inclusion of olive oil. The inclusion contains 5% of magnetic nanoparticles (20-30 nm diameter). The magnetoacoustic transducer, used in measurements, was a hybrid system composed of an AC biosusceptometer (ACB) with an ultrasonic transducer fixed in its core. Using ultrasound power Doppler image mode was possible to obtain quantitative data on the location and distribution of the particles. On the other hand, using susceptometric image it is possible to estimate the concentration of nanoparticles. Thus, it was shown the complementarity of the data obtained by ultrasound and magnetic images, as well as the feasibility of using magnetic nanoparticles with a future contrast . Palavras-chave: Ultrassom, Doppler, Susceptometria, nanopartículas, vibromagnetoacustografia.

Spatial distributions of the derivative of the electric field induced in a planar semi-infinite tissue model by various current-carrying coils and their utility in neural stimulation are evaluated. Analytical expressions are obtained for the electric field and its spatial derivatives produced by an infinitely short current element. Fields and their derivatives for an arbitrarily shaped coil are then obtained by numerical summation of contributions from all the elements forming the coil. The simplicity of the solution and a very short computation time make this method particularly attractive for gaining a physical insight into the spatial behavior of the stimulating parameter and for the optimization of coils. Such analysis is useful as the first step before undertaking a more complex numerical analysis of a model more closely representing the tissue geometry and heterogeneity.