Fields Of Different Strengths Research Articles

Effects of electromagnetic field on the nitrogen, protein and chlorophyll<br>content and peroxidase enzyme activity in oil palm (Elaeis guineensis Jacq.)<br>leaves

The effects of electromagnetic fields (EMF) from 275 kV high voltage transmission line on physiological, biochemical and antioxidant system changes in oil palm leaves were investigated under field conditions. Oil palm leaves were exposed to EMF from power lines at distances of 0, 8.8, 17.6, 26.4, 35.2, 44, 52.8 and 61.6 m away from the transmission lines for six months and seven years. The results showed that EMF exposure increased the content of chlorophyll a, b and the total chlorophyll in oil palm leaves planted nearer to the power lines (at 8.8 m) and decreased it with increasing distance from the lines. The protein banding profile of the oil palm exposed to electromagnetic field of different strength for seven years were insignificantly different. Oil palm exposed to the EMF for six months had three different protein banding patterns, which were different in the banding intensities of certain protein bands. The peroxidase enzyme activity (POX) of oil palm directly below the 275 kV power line was significantly (p?0.05) higher. However, decreasing EMF strength signifying that exposure on oil palm for duration of both seven years and six months resulted in a stress related response. The POX activity bands from the oil palm exposed to EMF for both seven years and six months respectively showed that more banding intensity and number of bands were found in those planted nearer to the power lines with higher electromagnetic strength exposure.

Calculation of magnetization curves and probability distribution for monoclinic and uniaxial systems

We present the application of a simple classical statistical mechanics-based model to selected monoclinic and hexagonal model systems. In this model, we treat the magnetization as a classical vector whose angular orientation is dictated by the laws of equilibrium classical statistical mechanics. We calculate for these anisotropic systems, the magnetization curves, energy landscapes and probability distribution for different sets of relevant parameters and magnetic fields of different strengths and directions. Our results demonstrate a correlation between the most probable orientation of the magnetization vector, the system's parameters, and the external magnetic field.

Nanospray FAIMS Fractionation Provides Significant Increases in Proteome Coverage of Unfractionated Complex Protein Digests

High-field asymmetric waveform ion mobility spectrometry (FAIMS) is an atmospheric pressure ion mobility technique that can be used to reduce sample complexity and increase dynamic range in tandem mass spectrometry experiments. FAIMS fractionates ions in the gas-phase according to characteristic differences in mobilities in electric fields of different strengths. Undesired ion species such as solvated clusters and singly charged chemical background ions can be prevented from reaching the mass analyzer, thus decreasing chemical noise. To date, there has been limited success using the commercially available Thermo Fisher FAIMS device with both standard ESI and nanoLC-MS. We have modified a Thermo Fisher electrospray source to accommodate a fused silica pulled tip capillary column for nanospray ionization, which will enable standard laboratories access to FAIMS technology. Our modified source allows easily obtainable stable spray at flow rates of 300 nL/min when coupled with FAIMS. The modified electrospray source allows the use of sheath gas, which provides a fivefold increase in signal obtained when nanoLC is coupled to FAIMS. In this work, nanoLC-FAIMS-MS and nanoLC-MS were compared by analyzing a tryptic digest of a 1:1 mixture of SILAC-labeled haploid and diploid yeast to demonstrate the performance of nanoLC-FAIMS-MS, at different compensation voltages, for post-column fractionation of complex protein digests. The effective dynamic range more than doubled when FAIMS was used. In total, 10,377 unique stripped peptides and 1649 unique proteins with SILAC ratios were identified from the combined nanoLC-FAIMS-MS experiments, compared with 6908 unique stripped peptides and 1003 unique proteins with SILAC ratios identified from the combined nanoLC-MS experiments. This work demonstrates how a commercially available FAIMS device can be combined with nanoLC to improve proteome coverage in shotgun and targeted type proteomics experiments.

Conductivity enhancement induced by casting of polymer electrolytes under a magnetic field

We recently presented a procedure for orienting the polyethylene-oxide (PEO) helices in a direction perpendicular to the film plane by casting the polymer electrolytes (PE) under a magnetic field (MF). Here we study the influence of magnetic fields of different strengths and configurations on the structural properties and ionic conductivity of concentrated LiCF 3SO 3 (LiTf) and LiAsF 6:P(EO) pristine and composite polymer electrolytes containing γ-Fe 2O 3 nanoparticles. Some data of LiI:P(EO) system are shown for comparison. We suggest that the effect of type of salt (LiI, LiTf and LiAsF 6) on the structure–conductivity relationship of the polymer electrolytes cast under magnetic field is closely connected to the crystallinity of the PEO–LiX system. It was found that the higher the content of the crystalline phase and the size of spherulites in the typically cast salt-polymer system, the stronger the influence of the magnetic field on the conductivity enhancement when the electrolyte is cast and dried under MF. Casting of the PE from a high-dielectric-constant solvent results in disentanglement of the PEO chains, which facilitates even more the perpendicular orientation of helices under applied MF. The enhancement of ionic conductivity was appreciably higher in the PEs cast under strong NdFeB magnets than under SmCo. Both bulk (intrachain) and grain-boundary conductivities increase when a MF is applied, but the improvement in the grain-boundary conductivity – associated with ion-hopping between polymer chains – is more pronounced. For LiAsF 6:(PEO) 3 at 65 °C, the interchain conductivity increased by a factor of 75, while the intrachain conductivity increased by a factor of 11–14. At room temperature, the SEI resistance of these PEs, cast under NdFeB HMF, decreased by a factor of up to 7, as compared to the typically cast polymer electrolytes. The effect of MF on orientation is observed directly down to the molecular level by 7Li nuclear magnetic resonance measurements.

Vortical structures and turbulent bursts behind magnetic obstacles in transitional flow regimes

The present paper reports on numerical investigations of vortical structures in transient flow regimes generated by the local action of the Lorentz force on an electrically conductive fluid. The locally imposed non-uniform magnetic field generates similar effects as observed for flows over submerged solid obstacles. It is demonstrated that complex flow patterns can be generated by imposing magnetic fields of different strengths. The initial validation of the electromagnetically extended Navier–Stokes solver on unstructured numerical grids is performed in the low-Reynolds number range 100 ⩽ Re ⩽ 400 for different values of the magnetic interaction parameter. A generally good agreement is obtained in comparison with similar numerical studies of Votyakov et al. (2007, 2008) for the low-Reynolds number cases. Then, a series of simulations are performed in transitional flow regimes ( Re = 900) for different values of the interaction parameter ( N = 3, … , 25). Simulations demonstrated the appearance of vortex-shedding phenomena similar to the flows behind solid obstacles. In contrast to the solid obstacles, the magnetic obstacles also generated the vortical flow patterns inside the magnetically affected regions. This feature can be used for the flow control of electrically conductive fluids, for efficient enhancements of the wall-heat transfer or for better mixing of passive scalars. Despite the laminar inflow conditions, turbulent bursts are observed in the magnetic wake region for the Re = 900 case. The velocity spectra and spatial distributions of the long-time averaged second-moments of the velocity field demonstrated that turbulence was locally sustained in the proximity of the magnetic wake edge.

Electrorheology of suspensions of mesostructured and mesoporous silica in poly(dimethylsiloxane)

The effect of electric fields on the viscosity and shear stress of dispersions of mesostructured silicon dioxide powders and the products of their thermal treatment, that is, mesoporous silicas, in silicone oil is investigated. Mesostructured silicon dioxide powders are prepared using different structuring reagents, namely, octylamine, dodecylamine, and polyethylenimine. It is shown that the shear stresses developing in systems containing mesostructured powders as dispersed phases under the action of electric fields are several times higher than those in dispersions of mesoporous materials. The shear stresses developing in the systems containing powders of mesostructured materials as dispersed phases under the effect of electric fields depend on the nature of organic substrates present in pores and the conductivity of the systems. Electrorheological effect in dispersions of mesoporous silicas slightly depends on the structure of the materials. The observed synergism may be related to the interactions between the components of a mesostructured material, which manifest themselves as a rise in interfacial polarization. The stress-strain curves were measured upon tensile and compression in electric fields of different strengths.

Computed effects of electric fields upon the CNO2 and NNO2 bonds of nitromethane and dimethylnitramine

AbstractWe report the results of a computational (B3PW91/6‐31G**) investigation of the effects of electric fields of different strengths and directions upon some properties related to the CNO2 and NNO2 bonds in nitromethane, H3CNO2, and dimethylnitramine, (H3C)2NNO2. We look at the interaction energies of the fields with the molecules, the dipole moments of the latter, the lengths of the CNO2 and NNO2 bonds, and we particularly focus upon their stretching vibration frequencies. The field‐induced frequency shifts are determined by means of a formula linking them to the dipole moment derivatives and the field strengths. This formula was derived originally for hydrogen‐bonded systems, but we show that it is applicable as well to these CNO2 and NNO2 bonds; their predicted relative frequency shifts correlate extremely well with directly computed Δω(ϵ) (R2 = 0.9992). It was found that the fields that reinforce the intrinsic H3CNO2 and (H3C)2NNO2 polarities also interact favorably energetically with the molecules and, particularly important, increase the CNO2 and NNO2 stretching frequencies. This presumably indicates the strengthening of these bonds. Fields in the opposite direction do the reverse. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009

Field-Dependent DNA Mobility in 20 nm High Nanoslits

The transport behavior of lambda-DNA (48 kbp) in fused silica nanoslits is investigated upon application of electrical fields of different strengths. The slit dimensions are 20 nm in height, 3 microm in width, and 500 microm in length. With fields of 30 kV/m or below, the molecules move fluently through the slits, while at higher electrical fields, the DNA molecules move intermittently, resulting in a strongly reduced mobility. We propose that the behavior can be explained by mechanical and/or field-induced dielectrophoretic DNA trapping due to the surface roughness in the nanoslits. The observation of preferential pathways and trapping sites of the lambda-DNA molecules through the nanoslits supports this hypothesis and indicates that the classical viscous friction models to explain the DNA movement in nanoslits needs to be modified to include these effects. Preliminary experiments with the smaller XbaI-digested litmus-DNA (2.8 kbp) show that the behavior is size-dependent, suggesting that the high field electrophoresis in nanoslits can be used for DNA separation.

The spin-1 and spin-3/2 model on a bilayer Bethe lattice with crystal field

A bilayer Ising model consisting of two Bethe lattices, each of which is coupledwith crystal fields of different strengths and each with a branching ratio ofq Ising spins with one of the layers having only spin-1 and the other having onlyspin-3/2, is laid over the top of the other and the two layers are tied together via an interactionbetween the vertically aligned spins. After obtaining the ground-state (GS) phase diagramson different possible planes depending on the given system parameters, the changes inthe order-parameters and the free energy are investigated by use of the exactrecursion relations in a pairwise approach to calculate the phase diagrams of themodel. The ferromagnetic ordering in each of the layers and ferromagnetic orantiferromagnetic ordering of the adjacent nearest-neighbor (NN) spins of thelayers are considered. The system presents both second- and first-order phasetransitions. The lines of the first-order phase transitions end on either the stableor unstable tricritical points or at the isolated critical points. The model alsodisplays one or two compensation temperatures when the bilinear interactionof the upper layer with spin-1 can compete with that of the lower layers withspin-3/2.

Influence of a Weak DC Electric Field on Root Meristem Architecture

Electric fields are an important environmental factor that can influence the development of plants organs. Such a field can either inhibit or stimulate root growth, and may also affect the direction of growth. Many developmental processes directly or indirectly depend upon the activity of the root apical meristem (RAM). The aim of this work was to examine the effects of a weak electric field on the organization of the RAM. Roots of Zea mays seedlings, grown in liquid medium, were exposed to DC electric fields of different strengths from 0.5 to 1.5 V cm(-1), with a frequency of 50 Hz, for 3 h. The roots were sampled for anatomical observation immediately after the treatment, and after 24 and 48 h of further undisturbed growth. DC fields of 1 and 1.5 V cm(-1) resulted in noticeable changes in the cellular pattern of the RAM. The electric field activated the quiescent centre (QC): the cells of the QC penetrated the root cap junction, disturbing the organization of the closed meristem and changing it temporarily into the open type. Even a weak electric field disturbs the pattern of cell divisions in plant root meristem. This in turn changes the global organization of the RAM. A field of slightly higher strength also damages root cap initials, terminating their division.

Influence of static magnetic fields on nerve regeneration in vitro

Our research involves determining how non-invasive electric and magnetic fields influence neuronal growth in vitro. In previous studies we have shown that pulsed electromagnetic fields (PEMF) as well as direct current (DC) alone stimulate neurite outgrowth from dorsal root ganglion explants [Sisken et al. 1984; Sisken et al. (Restor Neurol Neurosci 1:303–309, 1990); Greenebaum et al. (Bioelectromagnetics 17:293–302, 1996)]. A maximum response was obtained when nerve growth factor (NGF) was also present in the medium. The results of our experiments using static magnetic fields of different strengths are presented below and indicate that fields of high magnetic strength (450–900 gauss) with added NGF stimulate neurite outgrowth comparable to the response obtained with PEMF plus NGF.

Motor Adaptation as a Greedy Optimization of Error and Effort

Motor adaptation to a novel dynamic environment is primarily thought of as a process in which the nervous system learns to anticipate the environmental forces to eliminate kinematic error. Here we show that motor adaptation can more generally be modeled as a process in which the motor system greedily minimizes a cost function that is the weighted sum of kinematic error and effort. The learning dynamics predicted by this minimization process are a linear, auto-regressive equation with only one state, which has been identified previously as providing a good fit to data from force-field-type experiments. Thus we provide a new theoretical result that shows how these previously identified learning dynamics can be viewed as arising from an optimization of error and effort. We also show that the coefficients of the learning dynamics must fall within a specific range for the optimization model to be valid and verify with experimental data from walking in a force field that they indeed fall in this range. Finally, we attempted to falsify the model by performing experiments in two conditions (repeated exposure to a force field, exposure to force fields of different strengths) for which the single-state, auto-regressive equation might be expected to not fit the data well. We found however that the equation adequately captured the pattern of errors and thus conclude that motor adaptation to a force field can be approximated as an optimization of effort and error for a range of experimental conditions.

Accelerated Diffusion Test on the Intact Rock Mass

Abstract Contaminant transport through intact rock mass is predominantly diffusive and its modeling using the conventional laboratory tests is extremely time consuming. In addition, maintaining constant ambient conditions over a long duration is difficult and practically impossible. This necessitates modification of the conventional laboratory diffusion experiments so that the diffusion of ions through the intact rock mass is accelerated. To achieve this, researchers have employed an electric field across the samples of concrete and clays. However, the influence of the applied electric field on diffusion characteristics of the intact rock mass has not been studied in detail. With this in view, diffusion tests were conducted on the samples of chalk and sandstone by applying electric fields of different strength. Details of the testing methodology are presented in this paper. Efforts were also made to study the influence of the applied electric field on diffusion characteristics of these rocks.

Supercurrent density above 106A∕cm2 at 77K in a single-crystal film conductor of the cuprate high-Tc superconductor YBa2Cu3O7−δ—dream or reality?

Supercurrent transport phenomena in c-oriented epitaxial thin films of the the high-Tc superconducting (HTS) cuprate YBa2Cu3O7−δ (YBCO) with a high critical current density Jc(77K)⩾2×106A∕cm2 are investigated by four-probe transport measurements, low-frequency magnetic susceptibility studies, and SQUID magnetometry. The film samples are deposited on a single-crystal sapphire (r-cut) substrates with a CeO2 or LaAlO3(100) buffer layer by off-axis dc magnetron sputtering or pulsed laser ablation. A model of the mechanisms of Abrikosov vortex pinning and supercurrent limitation is developed and discussed by comparing its predictions with the results of measurements of the critical current and its dependence on applied magnetic fields of different strength and orientation and also with nanostructure data obtained by high-resolution transmission electron microscopy and electron diffraction in a backscattering geometry. It is shown that the low-angle subboundaries (LABs) formed between domains with a slight azimuthal misorientation during the epitaxial growth of the film play a key role in the phenomena observed in the transport of supercurrent. The tilt LABs form equidistant ordered rows of edge dislocations with nonsuperconducting cores about 3–4nm in diameter. The dislocation lines in the LABs are parallel to each other and perpendicular to the film plane. The average density of dislocations over the area of the film depends on the real statistics of the random system of LABs and can reach 1011cm−2. Since the diameter of the “normal” core of a dislocation is close to the diameter of the core of an Abrikosov vortex, the elementary pinning force of the vortex to the core of the dislocation is close to the maximum possible. The pinning on dislocation subboundaries has the following characteristics: 1) the achievement of high values Jc(77K)⩾2×106A∕cm2 and Jc(20K)>107A∕cm2 in epitaxial films and conductors; 2) the existence of a “plateau” on the Jc(H) curve, i.e., Jc(H)=const for H<Hm; 3) a logarithmic decline of Jc(H) for H>Hm, i.e., at the transition from the single-particle pinning regime to the collective pinning of the vortex lattice on the statistical ensemble of randomly distributed dislocation subboundaries; 4) the existence of a threshold field Hp that determines the limit up to which the vortices in a thin film (d⩽λ) remain rectilinear and perpendicular to the film even in a field inclined at a large angle; 5) the evolution of the angle dependence of Jc(θ) with a change of field strength is in complete agreement with the model of dominant pinning on “threading” edge dislocations. A new “peak effect”—an increase of Jc(H‖ab) with increasing longitudinal field—is observed for the first time for H>Hm, i.e, after the end of the “plateau” Jc(H‖ab)=const.

Inactivation of Microorganisms Using Electrostatic Fields

This research investigated whether electrostatic fields can be used to inactivate surface-borne and airborne microorganisms. Vegetative cells of Pseudomonas fluorescens and Bacillus subtilis var. niger were deposited on filters and subjected to electrostatic fields of different strengths and polarities for controlled time periods. In addition, P. fluorescens bacteria, which represent sensitive species, were aerosolized and exposed to electrostatic fields of up to +/- 10 kV/cm. The results have shown that more than 90% of the P. fluorescens cells deposited on the surface of nonconductive filters are inactivated when fields of 15 kV/cm are applied for 30 min or longer. Similar effects were observed when P. fluorescens were exposed to fields of 5 and 10 kV/cm for 2 h. In contrast, the culturability of B. subtilisvar. niger cells exposed under the same conditions did not substantially decrease. Exposure of airborne P. fluorescens to +/- 10 kV/cm for 30 s also did not result in a significant reduction of culturability. This research has shown that specific combinations of electrostatic field strength and exposure time can be used to effectively inactivate certain bacterial cells deposited on nonconductive surfaces. For the investigated conditions, the treatment was not effective for bacteria in the airborne state.

Hysteresis of dielectric properties of Li-Ti-Ferrite ceramics

Field dependences of Li-Ti ferrite ceramics polarization are obtained. When related to temperature, these dependences exhibit either non-linear behavior or non-linearity and hysteresis. Electric Barkhausen’s pulses are revealed. Temperature dependences of the electric pulse heights are obtained after re-polarization of the specimens in the electric fields of different strengths. The results provide evidence on the presence of ferroelectric properties in Li-Ti ferrite ceramics.

Electrically induced dynamic processes in nematic liquid crystals: H1 nuclear magnetic resonance investigations

The director reorientation of some nematic liquid crystals in the presence of both magnetic and electric field is described by a modified from of the Leslie equation. Proton nuclear magnetic resonance experiments observing static director orientations in different angles between the director and the magnetic field are described together with reorientation experiments driven by various electric fields. A new technique to measure Δχ/Δε is presented which gives direct access to the anisotropies without any influence of elastic properties. Using electric fields of different strength and in different angles with respect to the magnetic field the dynamic processes in liquid crystals can be investigated in a very flexible way. A number of experiments investigating the homogeneous director reorientation in the electric field is presented. As one result the rotational viscosity was determined. As a surprising result we found a homogeneous reorientation in the electric field and an inhomogeneous reorientation back in the magnetic field even though the initial angles between the director and the external field were the same.

Haptic Device Working with an Electrorheological Fluid

A haptic device based on an electrorheological fluid has been designed and tested. The device is similar to ajoystick which controls the motion of a cursor on a computer screen. In electric fields of different strength the shear stress of the electrorheological fluid is increased accordingly, which is perceived by the user by different resistance forces against the motion of the joystick. Controlled by the software the user can feel if the cursor enters a selected field on the screen. Such haptic devices can be useful in various possible applications like supporting tools for the operation of machines, assisting interfaces for blind persons working with a computer, virtual reality or computer games. The design of the haptic device, its components and the electrorheological fluid used are described.

Penetration of electrostatic fields and potentials through meshes, grids, or gauzes

A theoretical, computational, and experimental study has been carried out of the penetration of electrostatic fields and potentials through meshes. When a conducting partially transparent mesh is used to separate two regions of uniform static field of different strengths the potential distribution in the holes of the mesh is altered, causing the effective average potential of the mesh to become different from the potential applied to the mesh itself, which in turn gives rise to long-range changes to the fields and potentials on both sides of the mesh. The magnitudes of the effective changes in potential are investigated computationally for meshes that consist of either round wires or flat strips, in each case in either a parallel or crossed configuration. Semiempirical formulas are presented for the change in potential as a function of the fields on the two sides of the mesh and the size and spacing of the wires or strips. An experimental test using the shift in apparent energy of an electron-atom scattering resonance has been carried out.

Electric field effects on bioluminescent cells of Lampito mauritii: Electrofusion and enhancement of bioluminescence intensity

The bioluminescence of coelomic cells of Lampito mauritii has been monitored in oxygenated phosphate buffer saline (pH 7.4) after subjecting the coelomic cells to d.c. electric fields of different strengths; these cells have also been examined by electrochemical and optical techniques. The results suggest that the electric field produces poration of the bioluminescent cells, resulting in higher consumption of dissolved oxygen in the medium. Enhancement of bioluminescence intensity has also been observed. At field strengths of greater than 125 V cm −1, optical microscopic examination reveals that agglomeration and fusion of the cells has occurred.